Research ArticleRisk Assessment of Trace Element Contamination in DrinkingWater and Agricultural Soil A Study in Selected Chronic KidneyDisease of Unknown Etiology (CKDu) Endemic Areas in Sri Lanka
W P R T Perera 1 M D N R Dayananda 1 D M U C Dissanayake1
R A S D Rathnasekara1 W S M Botheju1 J A Liyanage 1 S K Weragoda2
and K A M Kularathne2
1Department of Chemistry Faculty of Science University of Kelaniya Kelaniya Sri Lanka2National Water Supply and Drainage Board Katugastota 20800 Sri Lanka
Correspondence should be addressed to W P R T Perera 2017_pereraklnaclk
Received 2 December 2020 Revised 14 January 2021 Accepted 20 January 2021 Published 29 January 2021
Academic Editor Zenilda Cardeal
Copyright copy 2021 W P R T Perera et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
Unexplained or unclear etiology of chronic kidney disease (CKDu) has been reported in Sri Lankarsquos North Central Province(NCP) for more than two decades Meanwhile high exposure to heavymetalsmetalloids and their accumulation are recognized asthe origin of many acute and chronic diseases in certain vulnerable human tissues including kidneys is study evaluates thecontamination status of heavy metalsmetalloids of the drinking water and agricultural soil in two CKDu endemic areas comparedwith a reference area in Sri Lanka based on common indexes and attribute of the commonly used fertilizers evaluated to identifythe basic sources of toxic metals in the agricultural soil Mean concentrations of heavy metalsmetalloids such as Mn Co As CdPb Cu Zn and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissiblelimits) In addition all sampling locations dropped below the medium range of the heavy metal pollution index of water (HPI15ndash40) Geoaccumulation indexes (Igeo) of soil reveal that paddy soil in CKDu endemic areas is being moderately polluted withtoxic metalsmetalloids such as As Pb Cu Ni Cr Zn and Cd On the other hand the application of fertilizers which contained ahigh dose of toxic metals could be the driving force for agricultural soil pollution and limitless application of low-quality fertilizerwould lead to more soil contamination with heavy metals Hence hazardous metals can be incorporated into the food chains viacontaminated paddy soil
1 Introduction
Chronic kidney disease unknown etiology (CKDu) was firstdiscovered in Sri Lanka in themid-1990s mainly found amongfarmers in Sri Lankarsquos North Central Province (NCP) sincethen the disease has spread dramatically over a span of twodecades including other agricultural areas of the country suchas the North NorthWest Eastern Uva and Central Provinces[1ndash3] Chronic kidney disease (CKD) is a noncommunicabledisease that is related to risk factors such as diabetes or hy-pertension past snakebites and urinary tract infections eaforementioned risk factors of CKD or family history of kidney
failures are not responsible for the occurrence of chronickidney disease of unknown etiology [4] Geographic ldquohotspotsrdquoof CKDu have emerged in a number of countries including ElSalvador Guatemala Mexico Nicaragua Bulgaria CroatiaSerbia India and Sri Lanka [5] and it is prevalent amongagricultural workers with several symptoms including fatiguepanting lack of appetite nausea and anemia [6]e studies ofCKDu in Sri Lanka are significant because of the increasingnumber of Sri Lankans who are suffering from CKDu since the1990s eg more than 50000 patients diagnosed with late-stagekidney disease and the majority of these patients are reportedfrom the North Central Province (NCP) [7] Hence potentially
HindawiJournal of ChemistryVolume 2021 Article ID 6627254 10 pageshttpsdoiorg10115520216627254
causative agents for the prevalence of kidney disease must bepresent in drinking water and soils of the endemic areas insufficient quantities [4]
Although some of the heavy metals are known to beenhancing human body functions the same heavy metalsabove their critical limits and some others are toxic forhuman beings [8] ere are so many major pathways tocontamination of groundwater and soil with nephrotoxiccontaminants such as heavy metals and counterions with thechemical applications due to the intense agriculture osetoxicants exist as clusters in the environment [9] And ex-posure to those may be linked to conditions such as neu-rotoxicity in human kidneys Exposure to metals such as AsCd Hg Cr Ni Mn and Fe present in the drinking watersignificantly collaborated with the functional and structuralintegrity of kidneys [10 11] According to the toxicologicalstudies on nephrotoxicity exposure to cation species of PbAs and Cd can be associated with renal tubular necrosis andexposure to heavy metals such as Pb Hg and Cd is directlyassociated with the collapse of glomeruli [12] Kidneydysfunction was correlated with high creatinine level whichresults from exposure to a low dose of Pb As and Cd Highcreatinine levels indicate a weak glomerular filtration pro-cess which means reduced ability to excrete waste productsfrom the blood through urine [9]
Agrochemicals and fertilizers are the most sensiblesource for heavy metal distribution in the paddy soil [13]Insecticides herbicides and fungicides are the primarysources of Cu Zn Cd Pb and As in the agricultural soilPhosphate nitrate potash and lime fertilizers are the mainsources of Cr Cd Cu Ni Zn Mn and Pb [14]
Moreover identifying the current status of the toxicmetal contamination in drinking water and agricultural soilis more significant because toxic metals can directly enter thehuman body via drinking water and human food chains canbe contaminated with toxic metals via polluted agriculturalsoil In order to identify the sources of the toxic metalsassessment of the frequently use fertilizers is more essentialas selected areas are fully agricultural areas Along with itthis study is expected to update the water and agriculturalsoil contamination levels and the current status of heavymetal pollution in two CKDu endemic areas in Sri Lankawith respect to the reference area (CKDu nonendemic) andillustrate and give a better understanding on heavy metalexposure using index-based assessment of drinking waterand the agricultural soil is comparison mainly focused onrevealing a piece of evidence of the contribution of toxicmetals to the prevalence of CKDu in selected endemic areas
2 Materials and Methods
21 Study Areas and Selection of Sampling Sites Two (02)CKDu endemic areas including Ambagaswewa GND(8deg11prime3070PrimeN 81deg0prime5708PrimeE) in Polonnaruwa District andEppawala GND (8deg8prime4010PrimeN 80deg24prime3773PrimeE) in Anu-radhapura District and a reference area that is Dam-bethalawa GND (7deg17prime168PrimeN 81deg32prime5235PrimeE) in AmparaDistrict in Sri Lanka were selected for the sampling based onthe recent hospital data obtained from the Ministry of
Health Sri Lanka GPS coordinates were recorded at eachand every sampling location using a GPS device All sam-pling procedures were done in April 2019 (dry season)
22 Sampling Sampling points for the drinking watersample collection were selected from shallow drinking waterwells (dug wells) located in the home gardens of the residentswhich are the main sources of water consumption in theirdaily life irty drinking water samples were collected fromeach CKDu hot spot and the reference site for the analysis ofcations and anions All the water samples were collected intoprewashed Teflon bottles for analysis and acidified withultrapure nitric acid (2 vv) (Sinopharm Shanghai China)All the water samples were stored at 4degC during transport tothe laboratory Agricultural lands were selected for soilsampling and twenty composite topsoil samples were col-lected from the paddy cultivated fields according to therandom sampling method in each selected CKDu hotspotand the reference site Composite soil samples were preparedby a combination of five samples from each location Asfrequently used fertilizers in paddy cultivations urea pot-ash and triple superphosphate fertilizer samples were col-lected from the stores in selected CKDu endemic areasFifteen composite fertilizer samples were collected in eachtype of fertilizers
23 Analysis Concentrations of metal elements in drinkingwater including Mn Co As Cd Pb Cu Zn Na K Al CaMg Fe and Ni were determined using inductively coupledplasma mass spectrometry (ICP-MS-7800-Agilent Ger-many) Multielement ICP-MS standards (AccuStandardUSA) were used for the instrumental calibration Two cal-ibration series (01 ppbndash10 ppb and 10 ppb to 1000 ppb) wereprepared using multielement standard Acidified watersamples with conc HNO3 (69 purity Sigma-AldrichIndia) were filtered through 045 μm syringe filters before theinsertion to the ICP-MS instrument e concentrations ofanions in water samples (including fluoride chloride ni-trate phosphate and sulfate) and fluoride chloride nitrateand sulfate contents in soil samples were measured using ionchromatography Sodium bicarbonate (Sigma-Aldrich In-dia CASRN 144-55-8) and sodium carbonate (Sigma-Aldrich India CASRN-497-19-7) were used as elutionsolution and sulfuric acid (Sigma-Aldrich India CASRN-7664-93-9) was used as regeneration solution ACS reagentgrade l000mgL stock solutions of considered counterionswere used to prepare the standards and prepared for a rangeof concentrations encompassing expected sample concen-trations Standards and collected samples were filtered Asmall volume of the sample (50mL) was introduced underthe flow rate of 07mLmin into the ion chromatograph(Metrohm Eco IC Switzerland) and the anions of interestwere separated and measured using a system comprised of aguard column analytical column suppressor device andconductivity detector
0200 g of each soil sample was digested using a mi-crowave digester (ETHOS EASY Italy) with adding1000mL of concentrated nitric acid Digested solutions
2 Journal of Chemistry
were diluted up to 2500mL with ultrapure water and1000mL of each digested soil solution was filtered through045 μm nylon syringe filters e determination of cationconcentrations (Cr Mn Fe Co As Cd Pb Cu Zn Mg CaNa K and Ni) in soil samples was carried out by the ICP-MSmethod (ICP-MS-8000-Agilent Germany) e calibrationseries (1 ppmndash50 ppm) was prepared using multielementstandard and 0200 g of each fertilizer sample (Urea Potashand Triple Superphosphate) was also used for the analysis ofheavy metalmetalloids (Cr Mn Fe Cu Zn As Cd and Pb)concentrations by the ICP-MS method
In order to determine the total phosphate concentrationin the soil 002M Truog extracting solution was prepared2654 g of (NH4)6Mo7O24middot4H2O (Sigma-Aldrich India) wasdissolved in 200mL of distilled water (warmed to 60degC) and2800mL Conc H2SO4 (95ndash97 purity EMPARTAreg ACSIndia) was diluted with 750ml of distilled water After bothsolutions cooled down to room temperature ammoniummolybdate solution was added slowly to the sulfuric acidsolution with shaking to prepare the molybdate reagent(25) 25 g of SnCl2middot2H2O (Sigma-Aldrich India) wasdissolved in 100mL of concentrated HCl and diluted to100mL with distilled water by rapid stirring A few pieces ofmetallic tin (Sn) were added to the solution after filtration toprepare stannous chloride solution A 1000mgL standardphosphorus solution was prepared by dissolving 04394 g ofKH2PO4 (Sigma-Aldrich India) in 1 L of H2SO4 (001molL) and a 40mgL solution was prepared as a phosphorusworking solution
Using the phosphorus working solution a calibrationcurve was constructed for the UV-visible spectrophotometerand measured the absorbance at 660 nm using a UV-visiblespectrophotometer (Agilent Cary 3500 Germany) Soilsamples for the phosphate analysis were prepared by adding30 g of a soil sample to the 10000mL extracting solutionemixture was shaken for about 10 minutes and allowed tostand for 15 minutes followed by filtration Both reagentswere mixed with the 5000mL aliquot of each soil solutionand measured the absorbance at 660 nm
24 Indexing Approach e present study attempts to usethe weighted arithmetic average mean method for cal-culating the HPI for the purpose of monitoring drinkingwater contamination levels in CKDu affected areas withrespect to the reference combining the concentrations ofCr Mn Cu Fe Pb Cd As and Zn A set of equationswere incorporated in calculating HPI for the drinkingwater samples e critical pollution index value is 100where higher HPI values indicate the greater damage tohuman health
e HPI model [15] was calculated as
HPI 1113936
ni1 Wi lowastQi
1113936ni1 Wi
(1)
where Q is the subindex of the ith parameter Wi is the unitweight of the ith parameter and n is the number of pa-rameters considered
Wi k
Si
(2)
where Wi is the unit of weightage k is the constant ofproportionality (k 1) and Si is the recommended standardfor the ith parameter according to the Sri Lankan standardsfor the drinking water
e subindex (Qi) of the ith parameter was calculatedaccording to Reza and Singh [6]
where Mi is the monitored value of the heavy metal of ithparameter in ppb Ii is the maximum desirable value (ideal)of the ith parameter and Si refers to the standard or per-missible limit for the ith parameter
25 Geoaccumulation Index (Igeo) for Agricultural SoilGeoaccumulation value was developed for the determina-tion of the degree of metal concentrations and the pollutionwhich is caused by the metals in soil segregates Geo-accumulation index (Igeo) was determined using the fol-lowing equation [16] (Muller 1979)
Igeo Cn
15 times Bn
(4)
where Cn is the measured concentration of the element insoil dust Bn is the geochemical background value and theconstant 15 allows us to analyze natural fluctuations in thecontent of a given substance in the environment and todetect a very small anthropogenic influence
26 Natural Background Concentration (NBC) NBC can becalculated by the method described by Ander et al 2013[17]
NBC x +(196lowast SD)
n
radic (5)
where x is the sample mean SD is the standard deviationand n is the number of samples Igeo was distinguished intoseven classes by Muller Table 1 represents the seven classesof geoaccumulation index by Muller
27 Geographical Data Treatment Geographic InformationSystem (GIS) is widely used for collecting diverse spatial dataand for overlay analysis in the spatial register domain torepresent spatially variable phenomena [18ndash20] GIS whichsynthesizes different and important quality data into aneasily understood format provides a way to summarizeoverall water or soil quality conditions in a manner that canbe clearly communicated to policymakers [21] and finallycan be incorporated with the decision-making process emaps which show the spatial distribution of heavy metalpollution in selected sampling areas were interpolated by theInverse Distance Weighted (IDW) tool and the Spatial
Journal of Chemistry 3
Autocorrelation tool (Moranrsquos index) using ArcGIS 102software
3 Results and Discussion
31 Assessment of Drinking Water In the drinking waterscenario the priority should be given to the fluoride toxicitybecause there have been many cases reported which wererelated to human kidney function failure due to fluoridetoxicity In accordance with the literature an investigation of210 children in China found that drinking water with morethan 200mgL fluoride had increased levels of N-acetylglucosamine (NAG) and y-glutamyl transpeptidase (yGT) intheir urine both of which are markers of renal tubulardamage [22]e present study has found that mean fluoridecontents in the CKDu endemic areas have exceeded thepermissible limits for drinking water fluoride (100mgL)(SLS 614 2013) (Figure 1)
e mean concentrations of other counterions whichwere analyzed in drinking water samples such as Clminus BrminusNOminus
3 PO3minus4 and SO3minus
4 (Table 2) have not exceeded per-missible limits defined in the Sri Lankan drinking waterquality standards (SLS 614 2013) in both endemic andnonendemic areas However Chandrajith et al 2010mentioned that even though no single geochemical pa-rameter could be clearly and directly correlated with theetiology of CKDu the unique hydrogeochemistry of thedrinking water is closely associated with the incidence ofthe disease In affected areas water quality needs to beassessed particularly combinations of various constituentssuch as metal elements and the hardness in combination[4]
According to the primary data gathered from bothCKDu affected areas (Table 3) Cd As Pb Cr Cu and Znconcentrations of drinking water were below the Sri Lankandrinking water quality guidelines [23] in the average me-dian maximum and minimum According to the literaturereview of the study another drinking water quality analysishas been conducted by a research group from Iran and theirstudies also revealed that the concentrations of As Cd CrPb Mn Zn Cu and Fe in drinking water were also lowerthan the maximum allowed concentrations advised by theUSEPA and WHO [22]
Additionally average cadmium and lead concentrationsin drinking water of both CKDu endemic areas were sig-nificantly higher (plt 005) than those of the reference areaAlthough the metal contents were found in low levels indrinking water in CKDu endemic areas long-term exposure
via drinking water may have harmful effects of etiologicalsignificance for CKDu due to bioaccumulation anddehydration
In recent years much attention has been given towardthe evaluation of heavy metal pollution in ground andsurface water with the development of a heavy metal pol-lution index (HPI) [24] In order to evaluate the suitability ofthe water for drinking the HPI of the drinking water in bothCKDu endemic areas can be considered e calculated HPIvalues were high in water from Eppawala GND which wasranging between 214 and 307e higher values of HPImaybe attributed due to the natural Apatite ore which is locatedin Eppawala Sri Lanka HPI for Ambagaswewa GND rangedfrom 252 to 278 and according to Moranrsquos index valuesresulted from the Spatial Autocorrelation tool showed thatthe heavy metal pollution in sampled drinking water sourcestends to be clustered throughout Ambagaswewa GND withthe higher concentrations Lower HPI values were recordedin Dambethalawa GND in Ampara district (reference site)where no CKDu patients were recorded (Figure 2)
However considering the classes of HPI all the samplinglocations fall under the medium range (HPI 15ndash40) isindicates that water is not critically polluted with respect tonephrotoxic heavy metals because the critical value of theHPI is 100 [15]
32 Evaluation of Agricultural Soil In the soil metals arefound in different forms such as inorganic compoundsmetal complexes and organometallic compounds Whenthese metal compounds dissolve in water they dissociateinto ions and tend to behave like cations they become part ofthe exchange complex and are available for absorption inplants by displacing the essential cations [25 26] In paddycultivated agricultural soils in Eppawala GND the totalaverage concentrations of toxic metals or metalloids carrieda sequence of CrgtZngtCugtPbgtAsgtCd e total averageconcentrations of toxic metals or metalloids in the agri-cultural soils in Ambagaswewa GND carried a sequence ofZngtCugtCrgt PbgtAsgtCd (Table 4) However the resultsindicate the total amount of toxic metalsmetalloids in thepaddy soil samples and some fraction may be absorbed bythe crop plants from the soil solution depending on theconditions of the soil environment
According to the paired t-test outcomes between CKDuprevalence areas and the reference the concentrations of CrAs and Cd of paddy soil in both CKDu hotspots weresignificantly higher than those of Dambethalawa GND (thereference) (at 95 confidence interval) All those threecontaminants are considered nephrotoxic contaminantsand synthetic agrochemicals are known to be the mainsources of heavy metal pollution in agricultural areas [27]
Mineral fertilizers used as a source of nutrients for plantsmay sometimes have a negative impact on the environmentmainly on soil and water Soil pollution with heavy metals isparticularly dangerous [28] Small contents of these metalsin nitrogen and potassium fertilizers do not pose any hazardof soil or plant contamination however phosphorus andmulticomponent fertilizers used for soil deacidification are
Table 1 Classes of geoaccumulation index (Muller 1979)
Igeo Igeo class Soilsediment quality0-0 0 Unpolluted0-1 1 Unpolluted to moderately polluted1-2 2 Moderately polluted2-3 3 Moderately polluted to highly polluted3-4 4 Highly polluted4-5 5 Highly polluted to very highly polluted5-6 gt5 Very highly polluted
4 Journal of Chemistry
usually a significant factor in heavy metal balance in theenvironment [10 29]
erefore Pearsonrsquos correlation was done on theavailable metals present in the sampled agricultural soils andphosphorus content in those soil samples to check whetherthere is a possible relationship between soil phosphoruscontent and the available metal contents e correlationmatrix of soil phosphate and heavy metals in selected paddygrown agricultural areas is shown in Table 5 According tothe results of the correlation matrix there was a significantpositive correlation between available soil phosphate contentand cadmium and chromium concentrations in agriculturalsoils (significant at p 005 and p 001 respectively) iscorrelation may be a result of the sulfuric acid used atmanufacturing fertilizers containing phosphorus in a water-soluble form During chemical processing of these minerals
mostly cadmium and chromium pass into the soluble phaseand then as a result of the technological process to thefertilizers erefore the rates of usage of phosphorus andmulticomponent fertilizers are usually determined on thebasis of their phosphorus contents and there is a directconnection between phosphorus content and an increase inheavy metal concentrations in agricultural soil Even worsethe fertilizers do not replace the trace minerals resulting inmineral-depleted soil When paddy grows in mineral-de-pleted soil it easily absorbs metals like Cd which is too toxicto the human kidneys [30]
Apart from that the prolonged exposure of crop plantsin soils with heavy metals increases their absorption capacityand depends on factors such as pH cation exchange ca-pacity organic matter content clay content and redoxpotential these determine the soil capacity to retain or
Pb
Cd
Fluoride
As
SLS limitsEppawala GNDAmbagaswewa GND
1 2 3 4 5 6 7 8 9 10 110Concentration (ppb)
02 04 06 08 1 12 14 16 18 20Concentration (ppm)
Figure 1 Graphical representation of lead cadmium arsenic concentrations and fluoride content in collected drinking water samples inboth CKDu hotspots Eppawala GND and Ambagasewewa GND
Table 2 Statistical evaluation of counterions of the drinking water sources in the selected CKDu prevalence areas Eppawala (EP) andAmbagaswewa (AM) GNDs and the reference (RE)
Variable Sampling site Mean SE mean Minimum Maximum
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
causative agents for the prevalence of kidney disease must bepresent in drinking water and soils of the endemic areas insufficient quantities [4]
Although some of the heavy metals are known to beenhancing human body functions the same heavy metalsabove their critical limits and some others are toxic forhuman beings [8] ere are so many major pathways tocontamination of groundwater and soil with nephrotoxiccontaminants such as heavy metals and counterions with thechemical applications due to the intense agriculture osetoxicants exist as clusters in the environment [9] And ex-posure to those may be linked to conditions such as neu-rotoxicity in human kidneys Exposure to metals such as AsCd Hg Cr Ni Mn and Fe present in the drinking watersignificantly collaborated with the functional and structuralintegrity of kidneys [10 11] According to the toxicologicalstudies on nephrotoxicity exposure to cation species of PbAs and Cd can be associated with renal tubular necrosis andexposure to heavy metals such as Pb Hg and Cd is directlyassociated with the collapse of glomeruli [12] Kidneydysfunction was correlated with high creatinine level whichresults from exposure to a low dose of Pb As and Cd Highcreatinine levels indicate a weak glomerular filtration pro-cess which means reduced ability to excrete waste productsfrom the blood through urine [9]
Agrochemicals and fertilizers are the most sensiblesource for heavy metal distribution in the paddy soil [13]Insecticides herbicides and fungicides are the primarysources of Cu Zn Cd Pb and As in the agricultural soilPhosphate nitrate potash and lime fertilizers are the mainsources of Cr Cd Cu Ni Zn Mn and Pb [14]
Moreover identifying the current status of the toxicmetal contamination in drinking water and agricultural soilis more significant because toxic metals can directly enter thehuman body via drinking water and human food chains canbe contaminated with toxic metals via polluted agriculturalsoil In order to identify the sources of the toxic metalsassessment of the frequently use fertilizers is more essentialas selected areas are fully agricultural areas Along with itthis study is expected to update the water and agriculturalsoil contamination levels and the current status of heavymetal pollution in two CKDu endemic areas in Sri Lankawith respect to the reference area (CKDu nonendemic) andillustrate and give a better understanding on heavy metalexposure using index-based assessment of drinking waterand the agricultural soil is comparison mainly focused onrevealing a piece of evidence of the contribution of toxicmetals to the prevalence of CKDu in selected endemic areas
2 Materials and Methods
21 Study Areas and Selection of Sampling Sites Two (02)CKDu endemic areas including Ambagaswewa GND(8deg11prime3070PrimeN 81deg0prime5708PrimeE) in Polonnaruwa District andEppawala GND (8deg8prime4010PrimeN 80deg24prime3773PrimeE) in Anu-radhapura District and a reference area that is Dam-bethalawa GND (7deg17prime168PrimeN 81deg32prime5235PrimeE) in AmparaDistrict in Sri Lanka were selected for the sampling based onthe recent hospital data obtained from the Ministry of
Health Sri Lanka GPS coordinates were recorded at eachand every sampling location using a GPS device All sam-pling procedures were done in April 2019 (dry season)
22 Sampling Sampling points for the drinking watersample collection were selected from shallow drinking waterwells (dug wells) located in the home gardens of the residentswhich are the main sources of water consumption in theirdaily life irty drinking water samples were collected fromeach CKDu hot spot and the reference site for the analysis ofcations and anions All the water samples were collected intoprewashed Teflon bottles for analysis and acidified withultrapure nitric acid (2 vv) (Sinopharm Shanghai China)All the water samples were stored at 4degC during transport tothe laboratory Agricultural lands were selected for soilsampling and twenty composite topsoil samples were col-lected from the paddy cultivated fields according to therandom sampling method in each selected CKDu hotspotand the reference site Composite soil samples were preparedby a combination of five samples from each location Asfrequently used fertilizers in paddy cultivations urea pot-ash and triple superphosphate fertilizer samples were col-lected from the stores in selected CKDu endemic areasFifteen composite fertilizer samples were collected in eachtype of fertilizers
23 Analysis Concentrations of metal elements in drinkingwater including Mn Co As Cd Pb Cu Zn Na K Al CaMg Fe and Ni were determined using inductively coupledplasma mass spectrometry (ICP-MS-7800-Agilent Ger-many) Multielement ICP-MS standards (AccuStandardUSA) were used for the instrumental calibration Two cal-ibration series (01 ppbndash10 ppb and 10 ppb to 1000 ppb) wereprepared using multielement standard Acidified watersamples with conc HNO3 (69 purity Sigma-AldrichIndia) were filtered through 045 μm syringe filters before theinsertion to the ICP-MS instrument e concentrations ofanions in water samples (including fluoride chloride ni-trate phosphate and sulfate) and fluoride chloride nitrateand sulfate contents in soil samples were measured using ionchromatography Sodium bicarbonate (Sigma-Aldrich In-dia CASRN 144-55-8) and sodium carbonate (Sigma-Aldrich India CASRN-497-19-7) were used as elutionsolution and sulfuric acid (Sigma-Aldrich India CASRN-7664-93-9) was used as regeneration solution ACS reagentgrade l000mgL stock solutions of considered counterionswere used to prepare the standards and prepared for a rangeof concentrations encompassing expected sample concen-trations Standards and collected samples were filtered Asmall volume of the sample (50mL) was introduced underthe flow rate of 07mLmin into the ion chromatograph(Metrohm Eco IC Switzerland) and the anions of interestwere separated and measured using a system comprised of aguard column analytical column suppressor device andconductivity detector
0200 g of each soil sample was digested using a mi-crowave digester (ETHOS EASY Italy) with adding1000mL of concentrated nitric acid Digested solutions
2 Journal of Chemistry
were diluted up to 2500mL with ultrapure water and1000mL of each digested soil solution was filtered through045 μm nylon syringe filters e determination of cationconcentrations (Cr Mn Fe Co As Cd Pb Cu Zn Mg CaNa K and Ni) in soil samples was carried out by the ICP-MSmethod (ICP-MS-8000-Agilent Germany) e calibrationseries (1 ppmndash50 ppm) was prepared using multielementstandard and 0200 g of each fertilizer sample (Urea Potashand Triple Superphosphate) was also used for the analysis ofheavy metalmetalloids (Cr Mn Fe Cu Zn As Cd and Pb)concentrations by the ICP-MS method
In order to determine the total phosphate concentrationin the soil 002M Truog extracting solution was prepared2654 g of (NH4)6Mo7O24middot4H2O (Sigma-Aldrich India) wasdissolved in 200mL of distilled water (warmed to 60degC) and2800mL Conc H2SO4 (95ndash97 purity EMPARTAreg ACSIndia) was diluted with 750ml of distilled water After bothsolutions cooled down to room temperature ammoniummolybdate solution was added slowly to the sulfuric acidsolution with shaking to prepare the molybdate reagent(25) 25 g of SnCl2middot2H2O (Sigma-Aldrich India) wasdissolved in 100mL of concentrated HCl and diluted to100mL with distilled water by rapid stirring A few pieces ofmetallic tin (Sn) were added to the solution after filtration toprepare stannous chloride solution A 1000mgL standardphosphorus solution was prepared by dissolving 04394 g ofKH2PO4 (Sigma-Aldrich India) in 1 L of H2SO4 (001molL) and a 40mgL solution was prepared as a phosphorusworking solution
Using the phosphorus working solution a calibrationcurve was constructed for the UV-visible spectrophotometerand measured the absorbance at 660 nm using a UV-visiblespectrophotometer (Agilent Cary 3500 Germany) Soilsamples for the phosphate analysis were prepared by adding30 g of a soil sample to the 10000mL extracting solutionemixture was shaken for about 10 minutes and allowed tostand for 15 minutes followed by filtration Both reagentswere mixed with the 5000mL aliquot of each soil solutionand measured the absorbance at 660 nm
24 Indexing Approach e present study attempts to usethe weighted arithmetic average mean method for cal-culating the HPI for the purpose of monitoring drinkingwater contamination levels in CKDu affected areas withrespect to the reference combining the concentrations ofCr Mn Cu Fe Pb Cd As and Zn A set of equationswere incorporated in calculating HPI for the drinkingwater samples e critical pollution index value is 100where higher HPI values indicate the greater damage tohuman health
e HPI model [15] was calculated as
HPI 1113936
ni1 Wi lowastQi
1113936ni1 Wi
(1)
where Q is the subindex of the ith parameter Wi is the unitweight of the ith parameter and n is the number of pa-rameters considered
Wi k
Si
(2)
where Wi is the unit of weightage k is the constant ofproportionality (k 1) and Si is the recommended standardfor the ith parameter according to the Sri Lankan standardsfor the drinking water
e subindex (Qi) of the ith parameter was calculatedaccording to Reza and Singh [6]
where Mi is the monitored value of the heavy metal of ithparameter in ppb Ii is the maximum desirable value (ideal)of the ith parameter and Si refers to the standard or per-missible limit for the ith parameter
25 Geoaccumulation Index (Igeo) for Agricultural SoilGeoaccumulation value was developed for the determina-tion of the degree of metal concentrations and the pollutionwhich is caused by the metals in soil segregates Geo-accumulation index (Igeo) was determined using the fol-lowing equation [16] (Muller 1979)
Igeo Cn
15 times Bn
(4)
where Cn is the measured concentration of the element insoil dust Bn is the geochemical background value and theconstant 15 allows us to analyze natural fluctuations in thecontent of a given substance in the environment and todetect a very small anthropogenic influence
26 Natural Background Concentration (NBC) NBC can becalculated by the method described by Ander et al 2013[17]
NBC x +(196lowast SD)
n
radic (5)
where x is the sample mean SD is the standard deviationand n is the number of samples Igeo was distinguished intoseven classes by Muller Table 1 represents the seven classesof geoaccumulation index by Muller
27 Geographical Data Treatment Geographic InformationSystem (GIS) is widely used for collecting diverse spatial dataand for overlay analysis in the spatial register domain torepresent spatially variable phenomena [18ndash20] GIS whichsynthesizes different and important quality data into aneasily understood format provides a way to summarizeoverall water or soil quality conditions in a manner that canbe clearly communicated to policymakers [21] and finallycan be incorporated with the decision-making process emaps which show the spatial distribution of heavy metalpollution in selected sampling areas were interpolated by theInverse Distance Weighted (IDW) tool and the Spatial
Journal of Chemistry 3
Autocorrelation tool (Moranrsquos index) using ArcGIS 102software
3 Results and Discussion
31 Assessment of Drinking Water In the drinking waterscenario the priority should be given to the fluoride toxicitybecause there have been many cases reported which wererelated to human kidney function failure due to fluoridetoxicity In accordance with the literature an investigation of210 children in China found that drinking water with morethan 200mgL fluoride had increased levels of N-acetylglucosamine (NAG) and y-glutamyl transpeptidase (yGT) intheir urine both of which are markers of renal tubulardamage [22]e present study has found that mean fluoridecontents in the CKDu endemic areas have exceeded thepermissible limits for drinking water fluoride (100mgL)(SLS 614 2013) (Figure 1)
e mean concentrations of other counterions whichwere analyzed in drinking water samples such as Clminus BrminusNOminus
3 PO3minus4 and SO3minus
4 (Table 2) have not exceeded per-missible limits defined in the Sri Lankan drinking waterquality standards (SLS 614 2013) in both endemic andnonendemic areas However Chandrajith et al 2010mentioned that even though no single geochemical pa-rameter could be clearly and directly correlated with theetiology of CKDu the unique hydrogeochemistry of thedrinking water is closely associated with the incidence ofthe disease In affected areas water quality needs to beassessed particularly combinations of various constituentssuch as metal elements and the hardness in combination[4]
According to the primary data gathered from bothCKDu affected areas (Table 3) Cd As Pb Cr Cu and Znconcentrations of drinking water were below the Sri Lankandrinking water quality guidelines [23] in the average me-dian maximum and minimum According to the literaturereview of the study another drinking water quality analysishas been conducted by a research group from Iran and theirstudies also revealed that the concentrations of As Cd CrPb Mn Zn Cu and Fe in drinking water were also lowerthan the maximum allowed concentrations advised by theUSEPA and WHO [22]
Additionally average cadmium and lead concentrationsin drinking water of both CKDu endemic areas were sig-nificantly higher (plt 005) than those of the reference areaAlthough the metal contents were found in low levels indrinking water in CKDu endemic areas long-term exposure
via drinking water may have harmful effects of etiologicalsignificance for CKDu due to bioaccumulation anddehydration
In recent years much attention has been given towardthe evaluation of heavy metal pollution in ground andsurface water with the development of a heavy metal pol-lution index (HPI) [24] In order to evaluate the suitability ofthe water for drinking the HPI of the drinking water in bothCKDu endemic areas can be considered e calculated HPIvalues were high in water from Eppawala GND which wasranging between 214 and 307e higher values of HPImaybe attributed due to the natural Apatite ore which is locatedin Eppawala Sri Lanka HPI for Ambagaswewa GND rangedfrom 252 to 278 and according to Moranrsquos index valuesresulted from the Spatial Autocorrelation tool showed thatthe heavy metal pollution in sampled drinking water sourcestends to be clustered throughout Ambagaswewa GND withthe higher concentrations Lower HPI values were recordedin Dambethalawa GND in Ampara district (reference site)where no CKDu patients were recorded (Figure 2)
However considering the classes of HPI all the samplinglocations fall under the medium range (HPI 15ndash40) isindicates that water is not critically polluted with respect tonephrotoxic heavy metals because the critical value of theHPI is 100 [15]
32 Evaluation of Agricultural Soil In the soil metals arefound in different forms such as inorganic compoundsmetal complexes and organometallic compounds Whenthese metal compounds dissolve in water they dissociateinto ions and tend to behave like cations they become part ofthe exchange complex and are available for absorption inplants by displacing the essential cations [25 26] In paddycultivated agricultural soils in Eppawala GND the totalaverage concentrations of toxic metals or metalloids carrieda sequence of CrgtZngtCugtPbgtAsgtCd e total averageconcentrations of toxic metals or metalloids in the agri-cultural soils in Ambagaswewa GND carried a sequence ofZngtCugtCrgt PbgtAsgtCd (Table 4) However the resultsindicate the total amount of toxic metalsmetalloids in thepaddy soil samples and some fraction may be absorbed bythe crop plants from the soil solution depending on theconditions of the soil environment
According to the paired t-test outcomes between CKDuprevalence areas and the reference the concentrations of CrAs and Cd of paddy soil in both CKDu hotspots weresignificantly higher than those of Dambethalawa GND (thereference) (at 95 confidence interval) All those threecontaminants are considered nephrotoxic contaminantsand synthetic agrochemicals are known to be the mainsources of heavy metal pollution in agricultural areas [27]
Mineral fertilizers used as a source of nutrients for plantsmay sometimes have a negative impact on the environmentmainly on soil and water Soil pollution with heavy metals isparticularly dangerous [28] Small contents of these metalsin nitrogen and potassium fertilizers do not pose any hazardof soil or plant contamination however phosphorus andmulticomponent fertilizers used for soil deacidification are
Table 1 Classes of geoaccumulation index (Muller 1979)
Igeo Igeo class Soilsediment quality0-0 0 Unpolluted0-1 1 Unpolluted to moderately polluted1-2 2 Moderately polluted2-3 3 Moderately polluted to highly polluted3-4 4 Highly polluted4-5 5 Highly polluted to very highly polluted5-6 gt5 Very highly polluted
4 Journal of Chemistry
usually a significant factor in heavy metal balance in theenvironment [10 29]
erefore Pearsonrsquos correlation was done on theavailable metals present in the sampled agricultural soils andphosphorus content in those soil samples to check whetherthere is a possible relationship between soil phosphoruscontent and the available metal contents e correlationmatrix of soil phosphate and heavy metals in selected paddygrown agricultural areas is shown in Table 5 According tothe results of the correlation matrix there was a significantpositive correlation between available soil phosphate contentand cadmium and chromium concentrations in agriculturalsoils (significant at p 005 and p 001 respectively) iscorrelation may be a result of the sulfuric acid used atmanufacturing fertilizers containing phosphorus in a water-soluble form During chemical processing of these minerals
mostly cadmium and chromium pass into the soluble phaseand then as a result of the technological process to thefertilizers erefore the rates of usage of phosphorus andmulticomponent fertilizers are usually determined on thebasis of their phosphorus contents and there is a directconnection between phosphorus content and an increase inheavy metal concentrations in agricultural soil Even worsethe fertilizers do not replace the trace minerals resulting inmineral-depleted soil When paddy grows in mineral-de-pleted soil it easily absorbs metals like Cd which is too toxicto the human kidneys [30]
Apart from that the prolonged exposure of crop plantsin soils with heavy metals increases their absorption capacityand depends on factors such as pH cation exchange ca-pacity organic matter content clay content and redoxpotential these determine the soil capacity to retain or
Pb
Cd
Fluoride
As
SLS limitsEppawala GNDAmbagaswewa GND
1 2 3 4 5 6 7 8 9 10 110Concentration (ppb)
02 04 06 08 1 12 14 16 18 20Concentration (ppm)
Figure 1 Graphical representation of lead cadmium arsenic concentrations and fluoride content in collected drinking water samples inboth CKDu hotspots Eppawala GND and Ambagasewewa GND
Table 2 Statistical evaluation of counterions of the drinking water sources in the selected CKDu prevalence areas Eppawala (EP) andAmbagaswewa (AM) GNDs and the reference (RE)
Variable Sampling site Mean SE mean Minimum Maximum
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
were diluted up to 2500mL with ultrapure water and1000mL of each digested soil solution was filtered through045 μm nylon syringe filters e determination of cationconcentrations (Cr Mn Fe Co As Cd Pb Cu Zn Mg CaNa K and Ni) in soil samples was carried out by the ICP-MSmethod (ICP-MS-8000-Agilent Germany) e calibrationseries (1 ppmndash50 ppm) was prepared using multielementstandard and 0200 g of each fertilizer sample (Urea Potashand Triple Superphosphate) was also used for the analysis ofheavy metalmetalloids (Cr Mn Fe Cu Zn As Cd and Pb)concentrations by the ICP-MS method
In order to determine the total phosphate concentrationin the soil 002M Truog extracting solution was prepared2654 g of (NH4)6Mo7O24middot4H2O (Sigma-Aldrich India) wasdissolved in 200mL of distilled water (warmed to 60degC) and2800mL Conc H2SO4 (95ndash97 purity EMPARTAreg ACSIndia) was diluted with 750ml of distilled water After bothsolutions cooled down to room temperature ammoniummolybdate solution was added slowly to the sulfuric acidsolution with shaking to prepare the molybdate reagent(25) 25 g of SnCl2middot2H2O (Sigma-Aldrich India) wasdissolved in 100mL of concentrated HCl and diluted to100mL with distilled water by rapid stirring A few pieces ofmetallic tin (Sn) were added to the solution after filtration toprepare stannous chloride solution A 1000mgL standardphosphorus solution was prepared by dissolving 04394 g ofKH2PO4 (Sigma-Aldrich India) in 1 L of H2SO4 (001molL) and a 40mgL solution was prepared as a phosphorusworking solution
Using the phosphorus working solution a calibrationcurve was constructed for the UV-visible spectrophotometerand measured the absorbance at 660 nm using a UV-visiblespectrophotometer (Agilent Cary 3500 Germany) Soilsamples for the phosphate analysis were prepared by adding30 g of a soil sample to the 10000mL extracting solutionemixture was shaken for about 10 minutes and allowed tostand for 15 minutes followed by filtration Both reagentswere mixed with the 5000mL aliquot of each soil solutionand measured the absorbance at 660 nm
24 Indexing Approach e present study attempts to usethe weighted arithmetic average mean method for cal-culating the HPI for the purpose of monitoring drinkingwater contamination levels in CKDu affected areas withrespect to the reference combining the concentrations ofCr Mn Cu Fe Pb Cd As and Zn A set of equationswere incorporated in calculating HPI for the drinkingwater samples e critical pollution index value is 100where higher HPI values indicate the greater damage tohuman health
e HPI model [15] was calculated as
HPI 1113936
ni1 Wi lowastQi
1113936ni1 Wi
(1)
where Q is the subindex of the ith parameter Wi is the unitweight of the ith parameter and n is the number of pa-rameters considered
Wi k
Si
(2)
where Wi is the unit of weightage k is the constant ofproportionality (k 1) and Si is the recommended standardfor the ith parameter according to the Sri Lankan standardsfor the drinking water
e subindex (Qi) of the ith parameter was calculatedaccording to Reza and Singh [6]
where Mi is the monitored value of the heavy metal of ithparameter in ppb Ii is the maximum desirable value (ideal)of the ith parameter and Si refers to the standard or per-missible limit for the ith parameter
25 Geoaccumulation Index (Igeo) for Agricultural SoilGeoaccumulation value was developed for the determina-tion of the degree of metal concentrations and the pollutionwhich is caused by the metals in soil segregates Geo-accumulation index (Igeo) was determined using the fol-lowing equation [16] (Muller 1979)
Igeo Cn
15 times Bn
(4)
where Cn is the measured concentration of the element insoil dust Bn is the geochemical background value and theconstant 15 allows us to analyze natural fluctuations in thecontent of a given substance in the environment and todetect a very small anthropogenic influence
26 Natural Background Concentration (NBC) NBC can becalculated by the method described by Ander et al 2013[17]
NBC x +(196lowast SD)
n
radic (5)
where x is the sample mean SD is the standard deviationand n is the number of samples Igeo was distinguished intoseven classes by Muller Table 1 represents the seven classesof geoaccumulation index by Muller
27 Geographical Data Treatment Geographic InformationSystem (GIS) is widely used for collecting diverse spatial dataand for overlay analysis in the spatial register domain torepresent spatially variable phenomena [18ndash20] GIS whichsynthesizes different and important quality data into aneasily understood format provides a way to summarizeoverall water or soil quality conditions in a manner that canbe clearly communicated to policymakers [21] and finallycan be incorporated with the decision-making process emaps which show the spatial distribution of heavy metalpollution in selected sampling areas were interpolated by theInverse Distance Weighted (IDW) tool and the Spatial
Journal of Chemistry 3
Autocorrelation tool (Moranrsquos index) using ArcGIS 102software
3 Results and Discussion
31 Assessment of Drinking Water In the drinking waterscenario the priority should be given to the fluoride toxicitybecause there have been many cases reported which wererelated to human kidney function failure due to fluoridetoxicity In accordance with the literature an investigation of210 children in China found that drinking water with morethan 200mgL fluoride had increased levels of N-acetylglucosamine (NAG) and y-glutamyl transpeptidase (yGT) intheir urine both of which are markers of renal tubulardamage [22]e present study has found that mean fluoridecontents in the CKDu endemic areas have exceeded thepermissible limits for drinking water fluoride (100mgL)(SLS 614 2013) (Figure 1)
e mean concentrations of other counterions whichwere analyzed in drinking water samples such as Clminus BrminusNOminus
3 PO3minus4 and SO3minus
4 (Table 2) have not exceeded per-missible limits defined in the Sri Lankan drinking waterquality standards (SLS 614 2013) in both endemic andnonendemic areas However Chandrajith et al 2010mentioned that even though no single geochemical pa-rameter could be clearly and directly correlated with theetiology of CKDu the unique hydrogeochemistry of thedrinking water is closely associated with the incidence ofthe disease In affected areas water quality needs to beassessed particularly combinations of various constituentssuch as metal elements and the hardness in combination[4]
According to the primary data gathered from bothCKDu affected areas (Table 3) Cd As Pb Cr Cu and Znconcentrations of drinking water were below the Sri Lankandrinking water quality guidelines [23] in the average me-dian maximum and minimum According to the literaturereview of the study another drinking water quality analysishas been conducted by a research group from Iran and theirstudies also revealed that the concentrations of As Cd CrPb Mn Zn Cu and Fe in drinking water were also lowerthan the maximum allowed concentrations advised by theUSEPA and WHO [22]
Additionally average cadmium and lead concentrationsin drinking water of both CKDu endemic areas were sig-nificantly higher (plt 005) than those of the reference areaAlthough the metal contents were found in low levels indrinking water in CKDu endemic areas long-term exposure
via drinking water may have harmful effects of etiologicalsignificance for CKDu due to bioaccumulation anddehydration
In recent years much attention has been given towardthe evaluation of heavy metal pollution in ground andsurface water with the development of a heavy metal pol-lution index (HPI) [24] In order to evaluate the suitability ofthe water for drinking the HPI of the drinking water in bothCKDu endemic areas can be considered e calculated HPIvalues were high in water from Eppawala GND which wasranging between 214 and 307e higher values of HPImaybe attributed due to the natural Apatite ore which is locatedin Eppawala Sri Lanka HPI for Ambagaswewa GND rangedfrom 252 to 278 and according to Moranrsquos index valuesresulted from the Spatial Autocorrelation tool showed thatthe heavy metal pollution in sampled drinking water sourcestends to be clustered throughout Ambagaswewa GND withthe higher concentrations Lower HPI values were recordedin Dambethalawa GND in Ampara district (reference site)where no CKDu patients were recorded (Figure 2)
However considering the classes of HPI all the samplinglocations fall under the medium range (HPI 15ndash40) isindicates that water is not critically polluted with respect tonephrotoxic heavy metals because the critical value of theHPI is 100 [15]
32 Evaluation of Agricultural Soil In the soil metals arefound in different forms such as inorganic compoundsmetal complexes and organometallic compounds Whenthese metal compounds dissolve in water they dissociateinto ions and tend to behave like cations they become part ofthe exchange complex and are available for absorption inplants by displacing the essential cations [25 26] In paddycultivated agricultural soils in Eppawala GND the totalaverage concentrations of toxic metals or metalloids carrieda sequence of CrgtZngtCugtPbgtAsgtCd e total averageconcentrations of toxic metals or metalloids in the agri-cultural soils in Ambagaswewa GND carried a sequence ofZngtCugtCrgt PbgtAsgtCd (Table 4) However the resultsindicate the total amount of toxic metalsmetalloids in thepaddy soil samples and some fraction may be absorbed bythe crop plants from the soil solution depending on theconditions of the soil environment
According to the paired t-test outcomes between CKDuprevalence areas and the reference the concentrations of CrAs and Cd of paddy soil in both CKDu hotspots weresignificantly higher than those of Dambethalawa GND (thereference) (at 95 confidence interval) All those threecontaminants are considered nephrotoxic contaminantsand synthetic agrochemicals are known to be the mainsources of heavy metal pollution in agricultural areas [27]
Mineral fertilizers used as a source of nutrients for plantsmay sometimes have a negative impact on the environmentmainly on soil and water Soil pollution with heavy metals isparticularly dangerous [28] Small contents of these metalsin nitrogen and potassium fertilizers do not pose any hazardof soil or plant contamination however phosphorus andmulticomponent fertilizers used for soil deacidification are
Table 1 Classes of geoaccumulation index (Muller 1979)
Igeo Igeo class Soilsediment quality0-0 0 Unpolluted0-1 1 Unpolluted to moderately polluted1-2 2 Moderately polluted2-3 3 Moderately polluted to highly polluted3-4 4 Highly polluted4-5 5 Highly polluted to very highly polluted5-6 gt5 Very highly polluted
4 Journal of Chemistry
usually a significant factor in heavy metal balance in theenvironment [10 29]
erefore Pearsonrsquos correlation was done on theavailable metals present in the sampled agricultural soils andphosphorus content in those soil samples to check whetherthere is a possible relationship between soil phosphoruscontent and the available metal contents e correlationmatrix of soil phosphate and heavy metals in selected paddygrown agricultural areas is shown in Table 5 According tothe results of the correlation matrix there was a significantpositive correlation between available soil phosphate contentand cadmium and chromium concentrations in agriculturalsoils (significant at p 005 and p 001 respectively) iscorrelation may be a result of the sulfuric acid used atmanufacturing fertilizers containing phosphorus in a water-soluble form During chemical processing of these minerals
mostly cadmium and chromium pass into the soluble phaseand then as a result of the technological process to thefertilizers erefore the rates of usage of phosphorus andmulticomponent fertilizers are usually determined on thebasis of their phosphorus contents and there is a directconnection between phosphorus content and an increase inheavy metal concentrations in agricultural soil Even worsethe fertilizers do not replace the trace minerals resulting inmineral-depleted soil When paddy grows in mineral-de-pleted soil it easily absorbs metals like Cd which is too toxicto the human kidneys [30]
Apart from that the prolonged exposure of crop plantsin soils with heavy metals increases their absorption capacityand depends on factors such as pH cation exchange ca-pacity organic matter content clay content and redoxpotential these determine the soil capacity to retain or
Pb
Cd
Fluoride
As
SLS limitsEppawala GNDAmbagaswewa GND
1 2 3 4 5 6 7 8 9 10 110Concentration (ppb)
02 04 06 08 1 12 14 16 18 20Concentration (ppm)
Figure 1 Graphical representation of lead cadmium arsenic concentrations and fluoride content in collected drinking water samples inboth CKDu hotspots Eppawala GND and Ambagasewewa GND
Table 2 Statistical evaluation of counterions of the drinking water sources in the selected CKDu prevalence areas Eppawala (EP) andAmbagaswewa (AM) GNDs and the reference (RE)
Variable Sampling site Mean SE mean Minimum Maximum
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
Autocorrelation tool (Moranrsquos index) using ArcGIS 102software
3 Results and Discussion
31 Assessment of Drinking Water In the drinking waterscenario the priority should be given to the fluoride toxicitybecause there have been many cases reported which wererelated to human kidney function failure due to fluoridetoxicity In accordance with the literature an investigation of210 children in China found that drinking water with morethan 200mgL fluoride had increased levels of N-acetylglucosamine (NAG) and y-glutamyl transpeptidase (yGT) intheir urine both of which are markers of renal tubulardamage [22]e present study has found that mean fluoridecontents in the CKDu endemic areas have exceeded thepermissible limits for drinking water fluoride (100mgL)(SLS 614 2013) (Figure 1)
e mean concentrations of other counterions whichwere analyzed in drinking water samples such as Clminus BrminusNOminus
3 PO3minus4 and SO3minus
4 (Table 2) have not exceeded per-missible limits defined in the Sri Lankan drinking waterquality standards (SLS 614 2013) in both endemic andnonendemic areas However Chandrajith et al 2010mentioned that even though no single geochemical pa-rameter could be clearly and directly correlated with theetiology of CKDu the unique hydrogeochemistry of thedrinking water is closely associated with the incidence ofthe disease In affected areas water quality needs to beassessed particularly combinations of various constituentssuch as metal elements and the hardness in combination[4]
According to the primary data gathered from bothCKDu affected areas (Table 3) Cd As Pb Cr Cu and Znconcentrations of drinking water were below the Sri Lankandrinking water quality guidelines [23] in the average me-dian maximum and minimum According to the literaturereview of the study another drinking water quality analysishas been conducted by a research group from Iran and theirstudies also revealed that the concentrations of As Cd CrPb Mn Zn Cu and Fe in drinking water were also lowerthan the maximum allowed concentrations advised by theUSEPA and WHO [22]
Additionally average cadmium and lead concentrationsin drinking water of both CKDu endemic areas were sig-nificantly higher (plt 005) than those of the reference areaAlthough the metal contents were found in low levels indrinking water in CKDu endemic areas long-term exposure
via drinking water may have harmful effects of etiologicalsignificance for CKDu due to bioaccumulation anddehydration
In recent years much attention has been given towardthe evaluation of heavy metal pollution in ground andsurface water with the development of a heavy metal pol-lution index (HPI) [24] In order to evaluate the suitability ofthe water for drinking the HPI of the drinking water in bothCKDu endemic areas can be considered e calculated HPIvalues were high in water from Eppawala GND which wasranging between 214 and 307e higher values of HPImaybe attributed due to the natural Apatite ore which is locatedin Eppawala Sri Lanka HPI for Ambagaswewa GND rangedfrom 252 to 278 and according to Moranrsquos index valuesresulted from the Spatial Autocorrelation tool showed thatthe heavy metal pollution in sampled drinking water sourcestends to be clustered throughout Ambagaswewa GND withthe higher concentrations Lower HPI values were recordedin Dambethalawa GND in Ampara district (reference site)where no CKDu patients were recorded (Figure 2)
However considering the classes of HPI all the samplinglocations fall under the medium range (HPI 15ndash40) isindicates that water is not critically polluted with respect tonephrotoxic heavy metals because the critical value of theHPI is 100 [15]
32 Evaluation of Agricultural Soil In the soil metals arefound in different forms such as inorganic compoundsmetal complexes and organometallic compounds Whenthese metal compounds dissolve in water they dissociateinto ions and tend to behave like cations they become part ofthe exchange complex and are available for absorption inplants by displacing the essential cations [25 26] In paddycultivated agricultural soils in Eppawala GND the totalaverage concentrations of toxic metals or metalloids carrieda sequence of CrgtZngtCugtPbgtAsgtCd e total averageconcentrations of toxic metals or metalloids in the agri-cultural soils in Ambagaswewa GND carried a sequence ofZngtCugtCrgt PbgtAsgtCd (Table 4) However the resultsindicate the total amount of toxic metalsmetalloids in thepaddy soil samples and some fraction may be absorbed bythe crop plants from the soil solution depending on theconditions of the soil environment
According to the paired t-test outcomes between CKDuprevalence areas and the reference the concentrations of CrAs and Cd of paddy soil in both CKDu hotspots weresignificantly higher than those of Dambethalawa GND (thereference) (at 95 confidence interval) All those threecontaminants are considered nephrotoxic contaminantsand synthetic agrochemicals are known to be the mainsources of heavy metal pollution in agricultural areas [27]
Mineral fertilizers used as a source of nutrients for plantsmay sometimes have a negative impact on the environmentmainly on soil and water Soil pollution with heavy metals isparticularly dangerous [28] Small contents of these metalsin nitrogen and potassium fertilizers do not pose any hazardof soil or plant contamination however phosphorus andmulticomponent fertilizers used for soil deacidification are
Table 1 Classes of geoaccumulation index (Muller 1979)
Igeo Igeo class Soilsediment quality0-0 0 Unpolluted0-1 1 Unpolluted to moderately polluted1-2 2 Moderately polluted2-3 3 Moderately polluted to highly polluted3-4 4 Highly polluted4-5 5 Highly polluted to very highly polluted5-6 gt5 Very highly polluted
4 Journal of Chemistry
usually a significant factor in heavy metal balance in theenvironment [10 29]
erefore Pearsonrsquos correlation was done on theavailable metals present in the sampled agricultural soils andphosphorus content in those soil samples to check whetherthere is a possible relationship between soil phosphoruscontent and the available metal contents e correlationmatrix of soil phosphate and heavy metals in selected paddygrown agricultural areas is shown in Table 5 According tothe results of the correlation matrix there was a significantpositive correlation between available soil phosphate contentand cadmium and chromium concentrations in agriculturalsoils (significant at p 005 and p 001 respectively) iscorrelation may be a result of the sulfuric acid used atmanufacturing fertilizers containing phosphorus in a water-soluble form During chemical processing of these minerals
mostly cadmium and chromium pass into the soluble phaseand then as a result of the technological process to thefertilizers erefore the rates of usage of phosphorus andmulticomponent fertilizers are usually determined on thebasis of their phosphorus contents and there is a directconnection between phosphorus content and an increase inheavy metal concentrations in agricultural soil Even worsethe fertilizers do not replace the trace minerals resulting inmineral-depleted soil When paddy grows in mineral-de-pleted soil it easily absorbs metals like Cd which is too toxicto the human kidneys [30]
Apart from that the prolonged exposure of crop plantsin soils with heavy metals increases their absorption capacityand depends on factors such as pH cation exchange ca-pacity organic matter content clay content and redoxpotential these determine the soil capacity to retain or
Pb
Cd
Fluoride
As
SLS limitsEppawala GNDAmbagaswewa GND
1 2 3 4 5 6 7 8 9 10 110Concentration (ppb)
02 04 06 08 1 12 14 16 18 20Concentration (ppm)
Figure 1 Graphical representation of lead cadmium arsenic concentrations and fluoride content in collected drinking water samples inboth CKDu hotspots Eppawala GND and Ambagasewewa GND
Table 2 Statistical evaluation of counterions of the drinking water sources in the selected CKDu prevalence areas Eppawala (EP) andAmbagaswewa (AM) GNDs and the reference (RE)
Variable Sampling site Mean SE mean Minimum Maximum
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
usually a significant factor in heavy metal balance in theenvironment [10 29]
erefore Pearsonrsquos correlation was done on theavailable metals present in the sampled agricultural soils andphosphorus content in those soil samples to check whetherthere is a possible relationship between soil phosphoruscontent and the available metal contents e correlationmatrix of soil phosphate and heavy metals in selected paddygrown agricultural areas is shown in Table 5 According tothe results of the correlation matrix there was a significantpositive correlation between available soil phosphate contentand cadmium and chromium concentrations in agriculturalsoils (significant at p 005 and p 001 respectively) iscorrelation may be a result of the sulfuric acid used atmanufacturing fertilizers containing phosphorus in a water-soluble form During chemical processing of these minerals
mostly cadmium and chromium pass into the soluble phaseand then as a result of the technological process to thefertilizers erefore the rates of usage of phosphorus andmulticomponent fertilizers are usually determined on thebasis of their phosphorus contents and there is a directconnection between phosphorus content and an increase inheavy metal concentrations in agricultural soil Even worsethe fertilizers do not replace the trace minerals resulting inmineral-depleted soil When paddy grows in mineral-de-pleted soil it easily absorbs metals like Cd which is too toxicto the human kidneys [30]
Apart from that the prolonged exposure of crop plantsin soils with heavy metals increases their absorption capacityand depends on factors such as pH cation exchange ca-pacity organic matter content clay content and redoxpotential these determine the soil capacity to retain or
Pb
Cd
Fluoride
As
SLS limitsEppawala GNDAmbagaswewa GND
1 2 3 4 5 6 7 8 9 10 110Concentration (ppb)
02 04 06 08 1 12 14 16 18 20Concentration (ppm)
Figure 1 Graphical representation of lead cadmium arsenic concentrations and fluoride content in collected drinking water samples inboth CKDu hotspots Eppawala GND and Ambagasewewa GND
Table 2 Statistical evaluation of counterions of the drinking water sources in the selected CKDu prevalence areas Eppawala (EP) andAmbagaswewa (AM) GNDs and the reference (RE)
Variable Sampling site Mean SE mean Minimum Maximum
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
mobilize heavy metals [31] Heavy metals in trace amountscan accumulate in soils of agricultural areas due to theircharacteristics and buffering capacity [32 33]
e risks the degree of toxicity and the persistence ofthe metals depend on the impact which soils receive bydifferent anthropogenic activitiese use and application ofgeoaccumulation indexes (Igeo) will identify the source ofpollutants and the degree of bioaccumulation in soil [34](Figure 3)
For all consideredmetals in the studied samples (for CKDuendemic areas) the Igeo values presented the decreasing orderof AsgtPbgtCugtNigtCrgtZngtCd for Eppawala GND andfor Ambagaswewa GND and the Igeo values presented thedecreasing order of AsgtCugtCrgtNigtCdgtPbgtZn emean Igeo values of all the studied metals in all sampling sitesindicate that the soils are slowly contaminated with heavymetals A trend like this was also revealed in another study ofagricultural soil analysis Rostami et al depict that agriculturalsoil was contaminated by Cr Cu Ni Pb and Zn but wasmoderately contaminated by Cd and As when considering theIgeo for the soil [34]
According to the findings soil samples from both CKDuprevalence areas and the reference area have moderatelycontaminatedpolluted with the metal contaminants andbelong to class 1 However none of the selected arearsquos paddysoil has exceeded the class 2 contamination level And alsomost of the Igeo values of the paddy soil in the CKDunonendemic area (reference) were much low with respect toCKDu endemic areas and agricultural soil in CKDu
endemic areas tends to convert to the contaminated positionwith some heavy metals
ose metal contaminants are important since they arecapable of decreasing crop production due to the risk ofbioaccumulation and biomagnification in the food chainand there is also a risk of superficial and groundwatercontamination [8] erefore remediation of agriculturalsoil contaminated by heavy metals is necessary in order toreduce the associated health risks make the land resourceavailable for agricultural production and enhance foodsecurity
33 Assessment of Toxic Metals in Commonly Used Fertilizersin Sri Lanka Another problematic case is agrochemicalsincluding fertilizers and pesticides which were introduced toSri Lanka in the 1970s Sri Lankan scientists reported thatpaddy soils in Mahaweli development areas (most of theCKDu endemic areas) are polluted with potentially toxicmetals and paddy soils in Sri Lanka are highly modified byartificial fertilizer applications [35] Table 6 shows thecontribution of the commonly used fertilizers to toxic metalcontamination in the soil in Sri Lanka According to thaturea which is commonly used in paddy cultivation as well asother cultivations in Sri Lanka has contained toxic metalssuch as Cd As Cr Pb Zn and Cu in noticeable amountsApart from that potash and triple superphosphate that areapplied in the paddy cultivation also have contained sig-nificant amounts of the aforementioned toxic metals except
Table 3 Statistical evaluation of concentrations of selected toxic metalsmetalloids of the drinking water sources in the selected areasEppawala (EP) and Ambagaswewa (AM) GNDs and the reference (RE)
Metal element Sample Mean plusmnSE mean Minimum Median Maximum
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
0 015 03 06 09 12Kilometers
HPIvalue
High 306983
Low 21363
High 278294
Low 252107
High 25675
Low 132413
Eppawala pointsEppawala GND
Ambagaswewa pointsAmbagaswewa GND
Dambetalawa pointsDambetalawa GND
N
(a) (b) (c)
HPIvalue
HPIvalue
Figure 2 Interpolation of heavy metal pollution index (HPI) in sampling location via drinking water analysis (a) Eppawala GND inAnuradhapura district (b) Ambagaswewa GND in Polonnaruwa district and (c) Dambethalawa GND in Ampara district (the reference)
Table 4 Descriptive statistics on concentrations of environmental toxicants including toxic metalsmetalloids and phosphates of paddy soilsamples (CKDu hotspots Eppawala (EP) and Ambagaswewa (AM) GNDs and the reference Dambethalawa (RE) GND)
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
Table 4 Continued
Variable Sample Mean SE mean Minimum Median Maximum
Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu Zn Cr Cd Pd As Ni Cu ZnEppawala Ambagaswewa Dambethalawa
Figure 3 Geoaccumulation index (Igeo) for heavy metals in paddy cultivated soil of selected GN areas
8 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
10 Journal of Chemistry
Cd and As Furthermore the risk of accumulation of toxicmetals is augmented due to the limitless application offertilizers in paddy cultivation Owing to toxic elementcontaminated fertilizer application in the paddy areas tanksediment is also contaminated as a long-term influenceHence those toxic metals can be incorporated into humanfood chains due to the consumption of freshwater fish[36ndash38]
4 Conclusions
Incorporation of the toxic metals into the food chains mainlyoccurs via contaminated paddy soil in rice consuming re-gions in the world as major food items such as the Asianregion In this study selected CKDu endemic areas in SriLanka are also identified as an agricultural area and for thefirst time this study compared the hazardous metal con-tamination of drinking water and agricultural soil in CKDuendemic areas with a nonendemic area in Sri Lanka Even ifthe current study reveals that toxic metal contents indrinking water samples in CKDu endemic areas were farbelow the permissible limits long-term exposure of thetoxic metals via drinking water may generate a risk Apartfrom that the persistence of the toxic metalsmetalloidssuch as Cr As Cd and Pb in frequently applying fertilizerswould be the major reason for paddy soil pollution withtoxic metalsmetalloids Geoaccumulation indexes revealthat paddy soil in selected CKDu endemic areas is beingtransferred to a moderate contamination stage and fre-quently metal-contaminated fertilizer applications mayaugment the risk of entering toxic metals into the paddyplants and then rice grins from the soil solution Hence thelong-term accumulation of toxic metalsmetalloids defi-nitely affects human kidney functions ere is an urgentneed to expand the evaluation of the quality of the fer-tilizersrsquo use in Sri Lanka
Data Availability
No data were used to support this study
Conflicts of Interest
e authors declare that they have no known competingfinancial interest or personal relationships that could haveappeared to influence the work reported in this paper
Authorsrsquo Contributions
W P R T Perera conceptualized the study and performed dataanalysis and investigations D M U C Dissanayake R A S DRathnasekara and K A M Kularathne were responsible forformal analysis andmethodology M D N R Dayananada andW S M Botheju prepared the original draft and further editedthemanuscript Janitha A Liyanage was responsible for fundingacquisition resources and supervision S K Weragoda wasresponsible for resources and supervision in instrumentation
Acknowledgments
is research was funded by the research project PSDSPCKDU0635 titled ldquoEstablish a CKDu Information andResearch Center at University of Kelaniya Sri Lankardquo eauthors would like to acknowledge the National Institute ofFundamental Studies (NIFS) Kandy Sri Lanka ey wouldlike to thank Amila T Kannangara Amitha SuriyaarachchiErandi Udayasiri and Sudesh Hemal for supporting samplecollection and analysis
References
[1] E S Wijewickrama N Gunawardena S Jayasinghe andC Herath ldquoCKD of unknown etiology (CKDu) in Sri Lanka amultilevel clinical case definition for surveillance and epi-demiological studiesrdquo Kidney International Reports vol 4no 6 p 781 2019
[2] S Rajapakse M C Shivanthan and M Selvarajah ldquoChronickidney disease of unknown etiology in Sri Lankardquo Interna-tional Journal of Occupational and Environmental Healthvol 22 no 3 p 259 2016
[3] M a C S Jayasumana P a Paranagama M D Amarasingheet al ldquoPossible link of chronic arsenic toxicity with chronickidney disease of unknown etiology in Sri Lankardquo Journal ofNatural Sciences Research vol 3 no 1 2013
[4] R Chandrajith S Nanayakkara K Itai et al ldquoChronic kidneydiseases of uncertain etiology (CKDue) in Sri Lanka geo-graphic distribution and environmental implicationsrdquo Envi-ronmental Geochemistry and Health vol 33 no 3 p 2672010
[5] S H Jadhav S N Sarkar R D Patil and H C TripathildquoEffects of subchronic exposure via drinking water to amixture of eight water-contaminating metals a biochemicaland histopathological study in male ratsrdquo Archives of Envi-ronmental Contamination and Toxicology vol 53 no 4pp 667ndash677 2007
[6] R Reza and G Singh ldquoHeavy metal contamination and itsindexing approach for river waterrdquo International Journal of
Table 6 Selected heavy metalmetalloid contents in fertilizer samples collected from the selected CKDu endemic area
Fertilizer typeMean metal contents in fertilizersplusmn SD
Cr (mgkg) Mn (mgkg) Fe (mgkg) Cu (mgkg) Zn (mgkg) As (mgkg) Cd (mgkg) Pb (mgkg)
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
[7] S Nanayakkara T Komiya N Ratnatunga et al ldquoTubu-lointerstitial damage as the major pathological lesion in en-demic chronic kidney disease among farmers in north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 17 no 3 pp 213ndash221 2012
[8] R A Wuana and F E Okieimen ldquoHeavy metals in con-taminated soils a review of sources chemistry risks and bestavailable strategies for remediationrdquo International ScholarlyResearch Notices vol 2011 Article ID 402647 20 pages 2011
[9] N I Agalakova and G P Gusev ldquoMolecular mechanisms ofcytotoxicity and apoptosis induced by inorganic fluoriderdquoISRN Cell Biology vol 2012 Article ID 403835 16 pages 2012
[10] O Abollino and M Aceto ldquoHeavy metals in agricultural soilsfrom Piedmont Italy Distribution speciation and chemo-metric data treatmentrdquo Chemosphere vol 49 p 545557 2002
[11] S J Cobbina Y Chen Z Zhou et al ldquoToxicity assessment dueto sub-chronic exposure to individual and mixtures of fourtoxic heavy metalsrdquo Journal of Hazardous Materials vol 294pp 109ndash120 2015
[12] M HWhittaker GWang X-Q Chen et al ldquoExposure to PbCd and as mixtures potentiates the production of oxidativestress precursors 30-day 90-day and 180-day drinking waterstudies in ratsrdquo Toxicology and Applied Pharmacologyvol 254 no 2 p 154 2011
[13] B P Panigrahy P K Singh A K Tiwari B Kumar andA Kumar ldquoAssessment of heavy metal pollution index forgroundwater around Jharia coalfield region Indiardquo Journal ofBiodiversity and Environmental Sciences vol 6 no 3pp 33ndash39 2015
[14] E Gimeno-Garcıa V Andreu and R Boluda ldquoHeavy metalsincidence in the application of inorganic fertilizers andpesticides to rice farming soilsrdquo Environmental Pollutionvol 92 no 1 pp 19ndash25 1996
[15] S V Mohan P Nithila and S J Reddy ldquoEstimation of heavymetals in drinking water and development of heavy metalpollution indexrdquo Journal of Environmental Science andHealth Part A Environmental Science and Engineering andToxicology vol 31 no 2 pp 283ndash289 1996
[16] G Muller ldquoIndex of geoaccumulation in sediments of therhine riverrdquo Geojournal vol 2 no 3 pp 108ndash118 1969
[17] E L Ander C C Johnson M R Cave B Palumbo-RoeC P Nathanail and R M Lark ldquoMethodology for the de-termination of normal background concentrations of con-taminants in English soilrdquo Science of the Total Environmentvol 454-455 pp 604ndash618 2013
[18] C Peter Keller ldquoGeographic information systems for geo-scientists modeling with GISrdquo Computers amp Geosciencesvol 21 no 9 pp 1ndash50 1996
[19] I Babiker and M A A Mohamed ldquoAssessment ofgroundwater contamination by nitrate leaching from inten-sive vegetable cultivation using geographical informationsystemrdquo Environment International vol 29 no 8pp 1009ndash1017 2004
[20] M Gupta and P K Srivastava ldquoIntegrating GIS and remotesensing for identification of groundwater potential zones inthe hilly terrain of Pavagarh Gujarat Indiardquo Water Inter-national vol 35 no 2 pp 233ndash245 2010
[21] S Singh N C Ghosh G Krishan R Galkate T omas andR K Jaiswal ldquoDevelopment of an overall water quality index(OWQI) for surface water in Indian contextrdquo Current WorldEnvironment vol 10 no 3 pp 813ndash822 2015
[22] M Dashtizadeh H Kamani S D Ashrafi et al ldquoHumanhealth risk assessment of trace elements in drinking tap waterin Zahedan city Iranrdquo Journal of Environmental HealthScience and Engineering vol 17 no 2 pp 1163ndash1169 2019
[23] SLS-614 Sri Lankan Drinking Water (Portable Water) QualityStandards httpswwwslsilkim agesdownloadsotheraccredited_tests_1pdf 2013
[24] R W Dharmaratne ldquoFluoride in drinking water and diet thecausative factor of chronic kidney diseases in the north centralprovince of Sri Lankardquo Environmental Health and PreventiveMedicine vol 20 no 4 pp 237ndash242 2015
[25] S J Reddy ldquoEncyclopaedia of Environmental Pollution andControlrdquo Environmental Media Environmental Media vol 1p 342 Karlia India1995
[26] S Sauve W Hendershot and H E Allen ldquoSolid-solutionpartitioning of metals in contaminated soils dependence onpH total metal burden and organic matterrdquo EnvironmentalScience amp Technology vol 34 no 7 pp 1125ndash1131 2000
[27] A Facchinelli L Sacchi and E Mallen ldquoMultivariate statisticalandGIS-based approach to identify heavymetal sources in soilsrdquoEnvironmental Pollution vol 114 pp 313ndash324 2000
[28] P A Kabata andH Pendias Trace Elements in Soil and PlantsCRC Press Boca Raton FL USA 2000
[29] S Khan Q Cao Y M Zheng Y Z Huang and Y G ZhuldquoHealth risks of heavy metals in contaminated soils and foodcrops irrigated with wastewater in Beijing Chinardquo Environ-mental Pollution vol 152 no 3 pp 686ndash692 2008
[30] A J P Navarro A I Aguilar and M J R Lopez ldquoAspectosbioquımicos y geneticos de la tolerancia y acumulacion demetales pesados en plantasrdquo Ecosistemas vol 16 pp 10ndash252007
[31] S V Adams P A Newcomb M M Shafer et al ldquoSources ofcadmium exposure among healthy premenopausal womenrdquoScience of the Total Environment vol 409 no 9 pp 1632ndash1637 2011
[32] B Lokeshappa K Shivpuri V Tripathi and K A DikshitldquoAssessment of toxic metals in agricultural producerdquo FoodPublic Health vol 2 pp 24ndash29 2012
[33] S G Rueda V J A Rodrıguez and M R MadrintildeanldquoMetodologıas para establecer valores de referencia de metalespesados en suelos agrıcolas perspectivas para Colombiardquo ActaAgronomica vol 60 pp 203ndash217 2011
[34] S Rostami H Kamani S Shahsavani and M HoseinildquoEnvironmental monitoring and ecological risk assessment ofheavy metals in farmland soilsrdquo Human and Ecological RiskAssessment An International Journal pp 1ndash13 In press
[35] G S Valladares O A d Camargo J R P d Carvalho andA M C Silva ldquoAssessment of heavy metals in soils of avineyard region with the use of principal component analy-sisrdquo Scientia Agricola vol 66 no 3 pp 361ndash367 2009
[36] G J M Trujillo and M M A Torres ldquoNiveles de con-taminacion en tres sectores de villavicencio a traves del ındicede geo-acumulacion (I-geo)rdquo Orinoquia vol 19 no 1 p 1092015
[37] H Ranasinghe ldquoOrganic agriculture as a sustainable solutionto chronic kidney disease unidentified (CKDu)rdquo InternationalJournal of Multidisciplinary Studies vol 3 no 2 pp 71ndash772016
[38] R T Perera N Dayananda S Botheju et al ldquoHeavy metalcontamination in surface sediments of major tanks in Anu-radhapura district A CKDu endemic district in Sri LankardquoInternational Journal of Environmental Quality vol 41pp 40ndash48 2021
