Research ArticleAssessment of Natural Radioactivity Levels andRadiation Hazards in Agricultural and Virgin Soil in theState of Kedah North of Malaysia
Ghazwa Alzubaidi1 Fauziah B S Hamid23 and I Abdul Rahman4
1Physics Department Faculty of Science University of Malaya Kuala Lumpur Malaysia2Institute of Biological Science Faculty of Science University of Malaya Kuala Lumpur Malaysia3Centre for Research in Waste Management Faculty of Science University of Malaya 50603 Kuala Lumpur Malaysia4School of Applied Physics Faculty of Science amp Technology Universiti Kebangsaan Selangor Malaysia
Correspondence should be addressed to Ghazwa Alzubaidi physics8outlookcom
Received 8 May 2016 Accepted 21 September 2016
Academic Editor Giuseppe Patane
Copyright copy 2016 Ghazwa Alzubaidi et al This 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 is properlycited
The activity concentrations of naturally occurring radionuclides 226Ra 232Th and 40Kwere determined in 30 agricultural and virginsoil samples randomly collected from Kedah north of Malaysia at a fertile soil depth of 0ndash30 cm Gamma-ray spectrometry wasapplied using high-purity germanium (HPGe) gamma-ray detector and a PC-based MCAThe mean radioactivity concentrationsof 226Ra 232Th and 40K were found to be 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1 respectively in agriculturalsoils and 6524 plusmn 200 8339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 respectively in virgin soils The radioactivity concentrations inagricultural soils are higher than those in virgin soils and compared with those reported in other countries The mean values ofradium equivalent activity (Raeq) absorbed dose rates 119863 (nGy hminus1) annual effective dose equivalent and external hazard index(119867ex) are 458785 Bq kgminus1 14162 nGy hminus1 and 0169mSv yminus1 respectively in agricultural soils and 214293 Bq kgminus1 8747 nGy hminus1and 0106mSv yminus1 respectively in virgin soils with average119867ex of 0525 Results were discussed and compared with those reportedin similar studies and with internationally recommended values
1 Introduction
Humans are exposed to natural radioactivity at differentlevels depending on natural radioactive elements presentin each area as such researchers investigated the naturalenvironmental radiation and radioactivity in soils to conductbackground checks and detect environmental radioactivity[1] The levels of radioactivity can be used to assess publicdose rates and radioactive contamination andpredict changesin environmental radioactivity caused by nuclear accidentsindustrial activities and other human activities [2]
Potassium-40 uranium-238 and thorium-232 and theirdecay products are important natural elements that con-tribute to a large part of the radiation dose receivedby humans thus far approximately 60 abundantly dis-tributed radionuclides have been identified Radionuclidesare encountered in terrestrial strata (soil or rocks) or lakes
and water bodies (ocean sea or lakes) and can be easilyaccumulated into the food chain [3]
Specific levels of terrestrial environmental radiation arerelated to the geological composition of each lithologicallyseparated area and to the contents of thorium (Th) uranium(U) and potassium (K) in rocks from which soils originateSoils are categorized into several types depending on theirphysical and chemical properties Many studies conductedworldwide showed that 238U including its decay products insoils and rocks and 232Th in monazite sands are the mainsources of high natural background radiation [4]
Natural environmental radiation and radioactivity in soilshave gained considerable research interest because humansare exposed to natural radioactivity at different levels depend-ing on natural radioactive minerals present in each regionworldwide [1]
Hindawi Publishing Corporatione Scientific World JournalVolume 2016 Article ID 6178103 9 pageshttpdxdoiorg10115520166178103
2 The Scientific World Journal
Kedah
Kedah
PerakKelantanTerengganu
Pahang
SelangorKuala Lumpur
Johor
0 100 200 300(km)
NegeriSembilanMelaka
PerlisSouth China Sea
Penang
Langkawi Island
Kedah
N
Alor Setar
Figure 1 Map of the area studied
Radionuclides in phosphate rocks can enter the envi-ronment through different mechanisms such as use ofphosphogypsum for building materials and for agricultureor fertilization of agricultural lands Direct fallout fromthe atmosphere on the vegetation is the primary source ofradiation contamination Fission product 137C is stronglyabsorbed and maintained by soil particles similar to naturalradionuclides which are widely distributed at different soildepths Therefore knowledge on radionuclide distributionin soils is essential to control health risks to the affectedpopulation
In this study the concentration of radioactivity and theradiation dose from agricultural soils of rice farms and virginsoils in Kedah Malaysia were analyzed Results can beused to determine public dose rates assess the performanceof epidemiological studies and maintain reference data toascertain changes in environmental radioactivity caused bynuclear industrial and other human activities
2 Experimental Procedures
21 Location of Study Area Surface soil samples were ran-domly collected from different locations of fertile soil inKedah in the northwestern part of Peninsular Malaysia6∘710158406240010158401015840N and 100∘2210158406456010158401015840E (Figure 1) and used tomeasure natural radioactivity in soil Kedah covers an area of9425 sq km and its agriculture industry is largely dedicatedto industrial crops About 518 ha of land in the state is utilizedfor agriculture 108 ha is covered by rubber trees 84 ha isplanted with oil palms and 112 ha is used for cultivating riceThemainland has a relatively flat terrain and is widely used togrow rice The average annual rainfall in Kedah ranges from2032mm to 2540mm
Vast agricultural areas in the state of Kedah and intensiveuse of phosphate fertilizers for reclaiming farmland haveimpelled researchers to investigate the concentration levelsof radionuclides in these areas and compare them with those
of virgin soil The levels of radioactivity concentration ofradionuclides in agriculture and virgin soil samples provideuseful information for monitoring of environmental radia-tion contamination
22 Samples Collection and Preparation Thirty samples werecollected at a depth of 0ndash30 cm from rice farms and virginsoil to measure natural radioactivity The samples were driedat 100∘C for 24 h in an oven and constant dry weights wereobtained to determine moisture content [23]
The dried samples were crushed into fine powder by usinga soil blender The powdered samples were sieved through100-micron mesh to keep uniform grain size and obtainaffine-grained homogenous soil samples for measurements[24] About 500 g of the homogenous soil sample was packedand sealed in an air-tight Marinelli beaker and stored for4 weeks before gamma-ray analysis this incubation periodallows 226Ra and its short-lived progenies to achieve secularequilibrium [25 26]
Gamma spectrometry analysis was performed using agamma-ray spectrometer with a p-type coaxial HPGe 120574-rayspectrometer and a p-type coaxial ORTEC GEM-25 HPGegamma-ray detector with 575mm diameter and 515mmthick crystals
The detector was set under the following conditionsoperating voltage +2800V relative efficiency 282 energyresolution 167 keV and full width at half maximum133MeV The detector was coupled with 60C emission and16 k Multichannel Analyzers for data acquisition Genie 2000software from Canberra was used to analyze the spectraThe detector was covered by a cylindrical lead shield with afixed bottom and a movable cover to reduce the interferenceof background radiation from terrestrial and extraterrestrialsources in the measured spectrum
An empty Marinelli beaker was counted in the same wayto remove the background radiation from the samples Afterthe measurement the background radiation was subtracted
The Scientific World Journal 3
Table 1 Gamma-ray energy and emission rate for 238 U 232Th and 40K radionuclides
Element Nuclide Half-life Gamma-ray energy 119864119892 (keV) Emission rate Sourcesorigin
to determine naturally occurring background distribution inthe environment around the detector [6]
Energy calibration and relative efficiency calibration ofthe spectrometer were performed using Marinelli calibrationsources containing the following 210Pb (4654 keV)241Am (59541 keV) 109Cd (88040 keV) 57C (122061 and136474 keV) 123mTe (15900 keV) 203Hg (279195 keV)113Sn (391698 keV) 85Sr (514007 keV) 137Cs (661657 keV)88Y (898042 and 1836063 keV) and 60Co (117322 and1332492 keV) The calibration source with an initial activityof 5109120583Ciwas obtained from Isotope Products Laboratories(Valencia CA 91355 USA)
Each sample and background data were counted for86400 s Gamma spectroscopy was used to determine theactivities of 238U 232Th and 40K
The specific activity of 226Ra was assessed from gamma-ray lines of 214Pb at 351 keV and 214Bi at 6093 and 17645 keVwhile the specific activity of 232Th had been evaluated fromgamma-ray lines of 228Ac at 3384 9111 and 9689 keV 212Pbat 23863 keV and 208Tl at 58319 keV The specific activityof 40K was directly determined from its gamma-ray line at14608 keV (Table 1)
3 Results and Discussion
31 The Activity Concentration Radioactivity concentrationwasmeasured using a gamma-ray spectrometerThe radioac-tivity of natural radionuclides namely uranium and thoriumseries as well as 40Kwas investigated in soil samples collectedfrom Kedah The primordial radionuclides of 226Ra 232Thand 40K were the three most important detected in the zone[27 28]
The radioactivity concentrations of these radionuclideswere calculated using the following formula [29]
119860 = 119873119875120574 times 120576 times119882
(Bq kgminus1) (1)
where 119860 = (Bq kgminus1) 119873 is net counts per second (CPS) =(sample CPS ndash background CPS) 119875120574 is intensity of theradionuclide 119864 is efficiency in and119882 is weight of samplein gram
The activity concentrations in 30 soil samples that weredetermined using HPGe detector are reported in (Table 2)
The measured activity concentration of 226Ra in agriculturalsoil samples ranged from 5893 plusmn 180 Bq kgminus1 to 16655 plusmn666 Bq kgminus1 with a mean value of 10208 plusmn 396 Bq kgminus1The concentration of 232Th ranged from 8798 plusmn 135 Bq kgminus1to 18045 plusmn 315 Bq kgminus1 with an average value of 13396 plusmn292 Bq kgminus1 The activity of 40K in agricultural soil samplesranged from 2022 plusmn 1172 Bq kgminus1 to 52917 plusmn 1019 Bq kgminus1with an average value of 32587 plusmn 983 Bq kgminus1
The activity concentration of 226Ra in virgin soil samplesvaried from 4511 plusmn 244 Bq kgminus1 to 1114 plusmn 13 Bq kgminus1with a mean value of 6524 plusmn 200 Bq kgminus1 The activityconcentration of 232Th ranged from 5183 plusmn 118 Bq kgminus1 to12735 plusmn 603 Bq kgminus1 with an average value of 8339 plusmn227 Bq kgminus1 The concentration of 40K radionuclides insoil samples ranged from 992 plusmn 121 Bq kgminus1 to 17285 plusmn771 Bq kgminus1 with an average value of 13698 plusmn 976 Bq kgminus1
The recommended reference levels of 226Ra 232Th and40K are 35 30 and 400 Bq kgminus1 respectively as listed inthe world average concentrations published by UNSCEAR(2000) The average concentrations of 226Ra and 232Thobtained in the present study are higher than the recom-mended reference levels The mean concentrations of thenatural radioactivity of virgin and agricultural soils werealso compared with the range and average of the naturalradioactivity concentration levels reported in other studies(Table 3) The mean concentrations of 226Ra 232Th and 40Kin virgin and agricultural soils in the present study are higherthan those reported by Ahmad et al [7] and Saleh et al [6]studies which was carried out by the first researcher to assessthe concentration radioactivity levels in agricultural areas ofpalm oil and bananas of Kedah
The results were also compared with those reported instudies conducted in other countries (Table 6) The meanactivity concentrations of natural radioactivity of 226Ra232Thand 40K in agricultural soil samples in the present studyare higher than those reported in agricultural soils of IndiaPakistan Algeria Egypt Thailand and Greece Phosphatefertilizers are extensively applied in the farmlands of ricetherefore the activity concentration of 226Ra was enhancedin these farmlands The enhancement in the radioactivityconcentration of 226Ra could be attributed to fertilizationwith phosphate rocks which contain substantial amounts
4 The Scientific World Journal
Table 2 The activity concentrations of 226Ra 232Th and 40K (Bq kgminus1) in agricultural and virgin soil samples collected from Kedah soil ofnorth Malaysia
Sample number Activity concentrations (Bq kgminus1) 119863(nGy hminus1)
of 238U 226Ra 232Th and 226Ra decay products this phe-nomenon results in the high activity of 40K in soil [30]
High radioactivity concentrations in the soil of thepresent studied area were also reported in previous studiesby Ahmad et al [7 31] but were lower than those of 226Ra232Th and 40K reported by Almayahi et al [5] and Ahmadet al [7 31] as well as by Saleh et al [6] in virgin soil samples
Themean radioactivity concentrations of 232Thand 226Rain virgin soil in the present study are higher than thosereported by UNSCEAR [2] (Table 7) whereas themean valueof 40K is slightly lower than that reported worldwide exceptfor Japan and Egypt
Variations in the radioactivity concentrations in soils ofvarious locations worldwide depend on the geographical andgeological conditions of the zone and the extent of fertilizerutilized in farmland [32 33]
32 Radiological Hazard Assessment
321 Assessment of Radium Equivalent (119877119886119890119902) Gamma-rayradiation hazards caused by specific radionuclides of 226Ra
232Th and 40K were evaluated using different indices Raeqwhich is the radium equivalent activity is the most widelyused radiation hazard index [34 35] Raeq is the weightedsum of activities of the three radionuclides based on thesupposition that 370 Bq kgminus1 226Ra 259 Bq kgminus1 232Th and481 Bq kgminus1 40K produce the same gamma-ray dose rate [36]Raeq is given by [37]
where 119862Ra 119862Th and 119862K are the activity concentrations of226Ra 232Th and 40K (in Bq kgminus1) respectively
To keep the annual radiation dose below 15mGy yminus1 themaximum value must be less than 370 Bq kgminus1 [8]
As shown in Table 5 Raeq of agricultural soil sampleswas within the range of 27475ndash81986 Bq kgminus1 with a meanvalue of 458785 Bq kgminus1 which exceeds the permissiblelimit (370 Bq kgminus1) recommended by the Organization forEconomic Cooperation and Development [38] The mean ofRaeq in the virgin soil was found to be 214293 Bq kg
minus1 whichis within the permissible limit
The Scientific World Journal 5
Table 3 The mean activity concentrations of natural radioactivity of agriculture and virgin soils in the present study were compared withthose from similar investigations performed in other countries
RegioncountryConcentration in soil (Bq kgminus1)
Reference226Ra 232Th 40KMean Range Mean Range Mean Range
Virgin soilMalaysia (Penang) 396 165 835 Almayahi et al [5]Malaysia (Pontian) 37 53 293 Saleh et al [6]Malaysia (Kedah) 5106 7844 12566 Ahmad et al [7]Malaysia 6524 4511ndash1114 8339 5183ndash12735 13698 992ndash1728 The present study
Agriculture soilMalaysia (Kedah) 8063 11687 20066 Ahmad et al [7]India 64 93 124 Singh et al [8]Pakistan 30 56 602 Tufail et al [9]Algeria 532 5003 311 Boukhenfouf and Boucenna [10]Egypt 43 57ndash140 54 9ndash139 183 22ndash319 Issa [11]Thailand 43 11ndash78 51 7ndash120 230 7ndash712 UNSCEAR [2]Malaysia 66 49ndash86 82 63ndash110 310 170ndash430 UNSCEAR [2]Greece 16 plusmn 6 12ndash26 55 plusmn 14 39ndash72 305 plusmn 59 222ndash376 Ioannides et al [12]Malaysia 10208 plusmn 396 5893ndash16655 13396 8798ndash18045 32587 2022ndash52917 The present study
The permissible limit of Raeq in building materials mustbe lt370 Bq kgminus1 which is equal to an annual dose of15mSv yminus1 [39 40]
322 Absorbed Dose Rate in Air (D) According to theguidelines provided by UNSCEAR [2] the absorbed gammadose rate 119863119877 (nGy hminus1) in air was determined at 1m abovethe ground surface to ensure uniformdistribution of radionu-clides This parameter can be used to assess any radiologicalhazard and radiation exposure from radionuclides in the soilthe absorbed dose rate was calculated using the followingformula [41]
where 119863119877 is the dose rate in nGy hminus1 and 119862Ra 119862Th and 119862Kare the activity concentrations (Bq kgminus1) of radium (226Ra)thorium (232Th) and potassium (40K) respectively
The absorbed dose rate indicates the received dose out-doors from radiation emitted by radionuclides in environ-mental materials Determination of this rate is the main stepfor evaluating health risk and this parameter is expressed ingray
Table 5 shows the absorbed dose rate calculated fromthe radioactivity concentrations of 226Ra 232Th and 40K inagricultural and virgin soil samples
The absorbed dose rate in agricultural soil ranged from9134 nGy hminus1 to 20734 nGy hminus1 with a mean value of14162 nGy hminus1 which is higher than the global mean valueof 60 nGy hminus1 established by UNSCEAR [2]
The average value of the absorbed dose rate 119863 (nGy hminus1)of agricultural soils in the present study is higher than thosereported in other countries (Table 6) The absorbed gamma
dose rate in virgin soil samples ranged from 6071 nGy hminus1 to12904 nGy hminus1 with an average value of 8747 nGy hminus1 whichis higher than the mean values reported in United StatesJapan Egypt Poland and Switzerland (Table 7) and the valuerecommended by UNSCEAR [2]
323 The Annual Effective Dose Rate Annual effective doseshould be calculated to assess the health effects of theabsorbed dose by using a conversion coefficient (07 SvGyminus1)to transform absorbed dose in air to the effective dosereceived by humans with an outdoor occupancy factor (02)which is equivalent to an outdoor occupancy of 20 and 80for the indoors [38 42]This factor is suitable for determiningthe pattern of life in the studied area Annual effective doserate (AEDR in mSv yminus1) received by the population can becalculated using [43 44]
Annual effective dose rate (mSv yminus1)
= Absorbed dose (nGy hminus1) times 8760 h sdot yrminus1 times 07
times (103mSv10minus9) times 02 (nGyminus1)
= 119863 times 12264 times 10minus3 (mSv yminus1)
(4)
where 119863 (nGh) is the total air absorbed dose rate in theoutdoors 8760 h is the number of hours in one year 02 isthe outdoor occupancy factor 07 SvGyminus1 is the conversioncoefficient fromabsorbed dose in air to effective dose receivedby adults 10minus6 is the conversion factor between nano- andmillimeasurements
The estimated annual effective dose in the agriculturalsoil samples ranged from 0112mSv yminus1 to 0254mSv yminus1 with
6 The Scientific World Journal
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Radionuclides in phosphate rocks can enter the envi-ronment through different mechanisms such as use ofphosphogypsum for building materials and for agricultureor fertilization of agricultural lands Direct fallout fromthe atmosphere on the vegetation is the primary source ofradiation contamination Fission product 137C is stronglyabsorbed and maintained by soil particles similar to naturalradionuclides which are widely distributed at different soildepths Therefore knowledge on radionuclide distributionin soils is essential to control health risks to the affectedpopulation
In this study the concentration of radioactivity and theradiation dose from agricultural soils of rice farms and virginsoils in Kedah Malaysia were analyzed Results can beused to determine public dose rates assess the performanceof epidemiological studies and maintain reference data toascertain changes in environmental radioactivity caused bynuclear industrial and other human activities
2 Experimental Procedures
21 Location of Study Area Surface soil samples were ran-domly collected from different locations of fertile soil inKedah in the northwestern part of Peninsular Malaysia6∘710158406240010158401015840N and 100∘2210158406456010158401015840E (Figure 1) and used tomeasure natural radioactivity in soil Kedah covers an area of9425 sq km and its agriculture industry is largely dedicatedto industrial crops About 518 ha of land in the state is utilizedfor agriculture 108 ha is covered by rubber trees 84 ha isplanted with oil palms and 112 ha is used for cultivating riceThemainland has a relatively flat terrain and is widely used togrow rice The average annual rainfall in Kedah ranges from2032mm to 2540mm
Vast agricultural areas in the state of Kedah and intensiveuse of phosphate fertilizers for reclaiming farmland haveimpelled researchers to investigate the concentration levelsof radionuclides in these areas and compare them with those
of virgin soil The levels of radioactivity concentration ofradionuclides in agriculture and virgin soil samples provideuseful information for monitoring of environmental radia-tion contamination
22 Samples Collection and Preparation Thirty samples werecollected at a depth of 0ndash30 cm from rice farms and virginsoil to measure natural radioactivity The samples were driedat 100∘C for 24 h in an oven and constant dry weights wereobtained to determine moisture content [23]
The dried samples were crushed into fine powder by usinga soil blender The powdered samples were sieved through100-micron mesh to keep uniform grain size and obtainaffine-grained homogenous soil samples for measurements[24] About 500 g of the homogenous soil sample was packedand sealed in an air-tight Marinelli beaker and stored for4 weeks before gamma-ray analysis this incubation periodallows 226Ra and its short-lived progenies to achieve secularequilibrium [25 26]
Gamma spectrometry analysis was performed using agamma-ray spectrometer with a p-type coaxial HPGe 120574-rayspectrometer and a p-type coaxial ORTEC GEM-25 HPGegamma-ray detector with 575mm diameter and 515mmthick crystals
The detector was set under the following conditionsoperating voltage +2800V relative efficiency 282 energyresolution 167 keV and full width at half maximum133MeV The detector was coupled with 60C emission and16 k Multichannel Analyzers for data acquisition Genie 2000software from Canberra was used to analyze the spectraThe detector was covered by a cylindrical lead shield with afixed bottom and a movable cover to reduce the interferenceof background radiation from terrestrial and extraterrestrialsources in the measured spectrum
An empty Marinelli beaker was counted in the same wayto remove the background radiation from the samples Afterthe measurement the background radiation was subtracted
The Scientific World Journal 3
Table 1 Gamma-ray energy and emission rate for 238 U 232Th and 40K radionuclides
Element Nuclide Half-life Gamma-ray energy 119864119892 (keV) Emission rate Sourcesorigin
to determine naturally occurring background distribution inthe environment around the detector [6]
Energy calibration and relative efficiency calibration ofthe spectrometer were performed using Marinelli calibrationsources containing the following 210Pb (4654 keV)241Am (59541 keV) 109Cd (88040 keV) 57C (122061 and136474 keV) 123mTe (15900 keV) 203Hg (279195 keV)113Sn (391698 keV) 85Sr (514007 keV) 137Cs (661657 keV)88Y (898042 and 1836063 keV) and 60Co (117322 and1332492 keV) The calibration source with an initial activityof 5109120583Ciwas obtained from Isotope Products Laboratories(Valencia CA 91355 USA)
Each sample and background data were counted for86400 s Gamma spectroscopy was used to determine theactivities of 238U 232Th and 40K
The specific activity of 226Ra was assessed from gamma-ray lines of 214Pb at 351 keV and 214Bi at 6093 and 17645 keVwhile the specific activity of 232Th had been evaluated fromgamma-ray lines of 228Ac at 3384 9111 and 9689 keV 212Pbat 23863 keV and 208Tl at 58319 keV The specific activityof 40K was directly determined from its gamma-ray line at14608 keV (Table 1)
3 Results and Discussion
31 The Activity Concentration Radioactivity concentrationwasmeasured using a gamma-ray spectrometerThe radioac-tivity of natural radionuclides namely uranium and thoriumseries as well as 40Kwas investigated in soil samples collectedfrom Kedah The primordial radionuclides of 226Ra 232Thand 40K were the three most important detected in the zone[27 28]
The radioactivity concentrations of these radionuclideswere calculated using the following formula [29]
119860 = 119873119875120574 times 120576 times119882
(Bq kgminus1) (1)
where 119860 = (Bq kgminus1) 119873 is net counts per second (CPS) =(sample CPS ndash background CPS) 119875120574 is intensity of theradionuclide 119864 is efficiency in and119882 is weight of samplein gram
The activity concentrations in 30 soil samples that weredetermined using HPGe detector are reported in (Table 2)
The measured activity concentration of 226Ra in agriculturalsoil samples ranged from 5893 plusmn 180 Bq kgminus1 to 16655 plusmn666 Bq kgminus1 with a mean value of 10208 plusmn 396 Bq kgminus1The concentration of 232Th ranged from 8798 plusmn 135 Bq kgminus1to 18045 plusmn 315 Bq kgminus1 with an average value of 13396 plusmn292 Bq kgminus1 The activity of 40K in agricultural soil samplesranged from 2022 plusmn 1172 Bq kgminus1 to 52917 plusmn 1019 Bq kgminus1with an average value of 32587 plusmn 983 Bq kgminus1
The activity concentration of 226Ra in virgin soil samplesvaried from 4511 plusmn 244 Bq kgminus1 to 1114 plusmn 13 Bq kgminus1with a mean value of 6524 plusmn 200 Bq kgminus1 The activityconcentration of 232Th ranged from 5183 plusmn 118 Bq kgminus1 to12735 plusmn 603 Bq kgminus1 with an average value of 8339 plusmn227 Bq kgminus1 The concentration of 40K radionuclides insoil samples ranged from 992 plusmn 121 Bq kgminus1 to 17285 plusmn771 Bq kgminus1 with an average value of 13698 plusmn 976 Bq kgminus1
The recommended reference levels of 226Ra 232Th and40K are 35 30 and 400 Bq kgminus1 respectively as listed inthe world average concentrations published by UNSCEAR(2000) The average concentrations of 226Ra and 232Thobtained in the present study are higher than the recom-mended reference levels The mean concentrations of thenatural radioactivity of virgin and agricultural soils werealso compared with the range and average of the naturalradioactivity concentration levels reported in other studies(Table 3) The mean concentrations of 226Ra 232Th and 40Kin virgin and agricultural soils in the present study are higherthan those reported by Ahmad et al [7] and Saleh et al [6]studies which was carried out by the first researcher to assessthe concentration radioactivity levels in agricultural areas ofpalm oil and bananas of Kedah
The results were also compared with those reported instudies conducted in other countries (Table 6) The meanactivity concentrations of natural radioactivity of 226Ra232Thand 40K in agricultural soil samples in the present studyare higher than those reported in agricultural soils of IndiaPakistan Algeria Egypt Thailand and Greece Phosphatefertilizers are extensively applied in the farmlands of ricetherefore the activity concentration of 226Ra was enhancedin these farmlands The enhancement in the radioactivityconcentration of 226Ra could be attributed to fertilizationwith phosphate rocks which contain substantial amounts
4 The Scientific World Journal
Table 2 The activity concentrations of 226Ra 232Th and 40K (Bq kgminus1) in agricultural and virgin soil samples collected from Kedah soil ofnorth Malaysia
Sample number Activity concentrations (Bq kgminus1) 119863(nGy hminus1)
of 238U 226Ra 232Th and 226Ra decay products this phe-nomenon results in the high activity of 40K in soil [30]
High radioactivity concentrations in the soil of thepresent studied area were also reported in previous studiesby Ahmad et al [7 31] but were lower than those of 226Ra232Th and 40K reported by Almayahi et al [5] and Ahmadet al [7 31] as well as by Saleh et al [6] in virgin soil samples
Themean radioactivity concentrations of 232Thand 226Rain virgin soil in the present study are higher than thosereported by UNSCEAR [2] (Table 7) whereas themean valueof 40K is slightly lower than that reported worldwide exceptfor Japan and Egypt
Variations in the radioactivity concentrations in soils ofvarious locations worldwide depend on the geographical andgeological conditions of the zone and the extent of fertilizerutilized in farmland [32 33]
32 Radiological Hazard Assessment
321 Assessment of Radium Equivalent (119877119886119890119902) Gamma-rayradiation hazards caused by specific radionuclides of 226Ra
232Th and 40K were evaluated using different indices Raeqwhich is the radium equivalent activity is the most widelyused radiation hazard index [34 35] Raeq is the weightedsum of activities of the three radionuclides based on thesupposition that 370 Bq kgminus1 226Ra 259 Bq kgminus1 232Th and481 Bq kgminus1 40K produce the same gamma-ray dose rate [36]Raeq is given by [37]
where 119862Ra 119862Th and 119862K are the activity concentrations of226Ra 232Th and 40K (in Bq kgminus1) respectively
To keep the annual radiation dose below 15mGy yminus1 themaximum value must be less than 370 Bq kgminus1 [8]
As shown in Table 5 Raeq of agricultural soil sampleswas within the range of 27475ndash81986 Bq kgminus1 with a meanvalue of 458785 Bq kgminus1 which exceeds the permissiblelimit (370 Bq kgminus1) recommended by the Organization forEconomic Cooperation and Development [38] The mean ofRaeq in the virgin soil was found to be 214293 Bq kg
minus1 whichis within the permissible limit
The Scientific World Journal 5
Table 3 The mean activity concentrations of natural radioactivity of agriculture and virgin soils in the present study were compared withthose from similar investigations performed in other countries
RegioncountryConcentration in soil (Bq kgminus1)
Reference226Ra 232Th 40KMean Range Mean Range Mean Range
Virgin soilMalaysia (Penang) 396 165 835 Almayahi et al [5]Malaysia (Pontian) 37 53 293 Saleh et al [6]Malaysia (Kedah) 5106 7844 12566 Ahmad et al [7]Malaysia 6524 4511ndash1114 8339 5183ndash12735 13698 992ndash1728 The present study
Agriculture soilMalaysia (Kedah) 8063 11687 20066 Ahmad et al [7]India 64 93 124 Singh et al [8]Pakistan 30 56 602 Tufail et al [9]Algeria 532 5003 311 Boukhenfouf and Boucenna [10]Egypt 43 57ndash140 54 9ndash139 183 22ndash319 Issa [11]Thailand 43 11ndash78 51 7ndash120 230 7ndash712 UNSCEAR [2]Malaysia 66 49ndash86 82 63ndash110 310 170ndash430 UNSCEAR [2]Greece 16 plusmn 6 12ndash26 55 plusmn 14 39ndash72 305 plusmn 59 222ndash376 Ioannides et al [12]Malaysia 10208 plusmn 396 5893ndash16655 13396 8798ndash18045 32587 2022ndash52917 The present study
The permissible limit of Raeq in building materials mustbe lt370 Bq kgminus1 which is equal to an annual dose of15mSv yminus1 [39 40]
322 Absorbed Dose Rate in Air (D) According to theguidelines provided by UNSCEAR [2] the absorbed gammadose rate 119863119877 (nGy hminus1) in air was determined at 1m abovethe ground surface to ensure uniformdistribution of radionu-clides This parameter can be used to assess any radiologicalhazard and radiation exposure from radionuclides in the soilthe absorbed dose rate was calculated using the followingformula [41]
where 119863119877 is the dose rate in nGy hminus1 and 119862Ra 119862Th and 119862Kare the activity concentrations (Bq kgminus1) of radium (226Ra)thorium (232Th) and potassium (40K) respectively
The absorbed dose rate indicates the received dose out-doors from radiation emitted by radionuclides in environ-mental materials Determination of this rate is the main stepfor evaluating health risk and this parameter is expressed ingray
Table 5 shows the absorbed dose rate calculated fromthe radioactivity concentrations of 226Ra 232Th and 40K inagricultural and virgin soil samples
The absorbed dose rate in agricultural soil ranged from9134 nGy hminus1 to 20734 nGy hminus1 with a mean value of14162 nGy hminus1 which is higher than the global mean valueof 60 nGy hminus1 established by UNSCEAR [2]
The average value of the absorbed dose rate 119863 (nGy hminus1)of agricultural soils in the present study is higher than thosereported in other countries (Table 6) The absorbed gamma
dose rate in virgin soil samples ranged from 6071 nGy hminus1 to12904 nGy hminus1 with an average value of 8747 nGy hminus1 whichis higher than the mean values reported in United StatesJapan Egypt Poland and Switzerland (Table 7) and the valuerecommended by UNSCEAR [2]
323 The Annual Effective Dose Rate Annual effective doseshould be calculated to assess the health effects of theabsorbed dose by using a conversion coefficient (07 SvGyminus1)to transform absorbed dose in air to the effective dosereceived by humans with an outdoor occupancy factor (02)which is equivalent to an outdoor occupancy of 20 and 80for the indoors [38 42]This factor is suitable for determiningthe pattern of life in the studied area Annual effective doserate (AEDR in mSv yminus1) received by the population can becalculated using [43 44]
Annual effective dose rate (mSv yminus1)
= Absorbed dose (nGy hminus1) times 8760 h sdot yrminus1 times 07
times (103mSv10minus9) times 02 (nGyminus1)
= 119863 times 12264 times 10minus3 (mSv yminus1)
(4)
where 119863 (nGh) is the total air absorbed dose rate in theoutdoors 8760 h is the number of hours in one year 02 isthe outdoor occupancy factor 07 SvGyminus1 is the conversioncoefficient fromabsorbed dose in air to effective dose receivedby adults 10minus6 is the conversion factor between nano- andmillimeasurements
The estimated annual effective dose in the agriculturalsoil samples ranged from 0112mSv yminus1 to 0254mSv yminus1 with
6 The Scientific World Journal
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
to determine naturally occurring background distribution inthe environment around the detector [6]
Energy calibration and relative efficiency calibration ofthe spectrometer were performed using Marinelli calibrationsources containing the following 210Pb (4654 keV)241Am (59541 keV) 109Cd (88040 keV) 57C (122061 and136474 keV) 123mTe (15900 keV) 203Hg (279195 keV)113Sn (391698 keV) 85Sr (514007 keV) 137Cs (661657 keV)88Y (898042 and 1836063 keV) and 60Co (117322 and1332492 keV) The calibration source with an initial activityof 5109120583Ciwas obtained from Isotope Products Laboratories(Valencia CA 91355 USA)
Each sample and background data were counted for86400 s Gamma spectroscopy was used to determine theactivities of 238U 232Th and 40K
The specific activity of 226Ra was assessed from gamma-ray lines of 214Pb at 351 keV and 214Bi at 6093 and 17645 keVwhile the specific activity of 232Th had been evaluated fromgamma-ray lines of 228Ac at 3384 9111 and 9689 keV 212Pbat 23863 keV and 208Tl at 58319 keV The specific activityof 40K was directly determined from its gamma-ray line at14608 keV (Table 1)
3 Results and Discussion
31 The Activity Concentration Radioactivity concentrationwasmeasured using a gamma-ray spectrometerThe radioac-tivity of natural radionuclides namely uranium and thoriumseries as well as 40Kwas investigated in soil samples collectedfrom Kedah The primordial radionuclides of 226Ra 232Thand 40K were the three most important detected in the zone[27 28]
The radioactivity concentrations of these radionuclideswere calculated using the following formula [29]
119860 = 119873119875120574 times 120576 times119882
(Bq kgminus1) (1)
where 119860 = (Bq kgminus1) 119873 is net counts per second (CPS) =(sample CPS ndash background CPS) 119875120574 is intensity of theradionuclide 119864 is efficiency in and119882 is weight of samplein gram
The activity concentrations in 30 soil samples that weredetermined using HPGe detector are reported in (Table 2)
The measured activity concentration of 226Ra in agriculturalsoil samples ranged from 5893 plusmn 180 Bq kgminus1 to 16655 plusmn666 Bq kgminus1 with a mean value of 10208 plusmn 396 Bq kgminus1The concentration of 232Th ranged from 8798 plusmn 135 Bq kgminus1to 18045 plusmn 315 Bq kgminus1 with an average value of 13396 plusmn292 Bq kgminus1 The activity of 40K in agricultural soil samplesranged from 2022 plusmn 1172 Bq kgminus1 to 52917 plusmn 1019 Bq kgminus1with an average value of 32587 plusmn 983 Bq kgminus1
The activity concentration of 226Ra in virgin soil samplesvaried from 4511 plusmn 244 Bq kgminus1 to 1114 plusmn 13 Bq kgminus1with a mean value of 6524 plusmn 200 Bq kgminus1 The activityconcentration of 232Th ranged from 5183 plusmn 118 Bq kgminus1 to12735 plusmn 603 Bq kgminus1 with an average value of 8339 plusmn227 Bq kgminus1 The concentration of 40K radionuclides insoil samples ranged from 992 plusmn 121 Bq kgminus1 to 17285 plusmn771 Bq kgminus1 with an average value of 13698 plusmn 976 Bq kgminus1
The recommended reference levels of 226Ra 232Th and40K are 35 30 and 400 Bq kgminus1 respectively as listed inthe world average concentrations published by UNSCEAR(2000) The average concentrations of 226Ra and 232Thobtained in the present study are higher than the recom-mended reference levels The mean concentrations of thenatural radioactivity of virgin and agricultural soils werealso compared with the range and average of the naturalradioactivity concentration levels reported in other studies(Table 3) The mean concentrations of 226Ra 232Th and 40Kin virgin and agricultural soils in the present study are higherthan those reported by Ahmad et al [7] and Saleh et al [6]studies which was carried out by the first researcher to assessthe concentration radioactivity levels in agricultural areas ofpalm oil and bananas of Kedah
The results were also compared with those reported instudies conducted in other countries (Table 6) The meanactivity concentrations of natural radioactivity of 226Ra232Thand 40K in agricultural soil samples in the present studyare higher than those reported in agricultural soils of IndiaPakistan Algeria Egypt Thailand and Greece Phosphatefertilizers are extensively applied in the farmlands of ricetherefore the activity concentration of 226Ra was enhancedin these farmlands The enhancement in the radioactivityconcentration of 226Ra could be attributed to fertilizationwith phosphate rocks which contain substantial amounts
4 The Scientific World Journal
Table 2 The activity concentrations of 226Ra 232Th and 40K (Bq kgminus1) in agricultural and virgin soil samples collected from Kedah soil ofnorth Malaysia
Sample number Activity concentrations (Bq kgminus1) 119863(nGy hminus1)
of 238U 226Ra 232Th and 226Ra decay products this phe-nomenon results in the high activity of 40K in soil [30]
High radioactivity concentrations in the soil of thepresent studied area were also reported in previous studiesby Ahmad et al [7 31] but were lower than those of 226Ra232Th and 40K reported by Almayahi et al [5] and Ahmadet al [7 31] as well as by Saleh et al [6] in virgin soil samples
Themean radioactivity concentrations of 232Thand 226Rain virgin soil in the present study are higher than thosereported by UNSCEAR [2] (Table 7) whereas themean valueof 40K is slightly lower than that reported worldwide exceptfor Japan and Egypt
Variations in the radioactivity concentrations in soils ofvarious locations worldwide depend on the geographical andgeological conditions of the zone and the extent of fertilizerutilized in farmland [32 33]
32 Radiological Hazard Assessment
321 Assessment of Radium Equivalent (119877119886119890119902) Gamma-rayradiation hazards caused by specific radionuclides of 226Ra
232Th and 40K were evaluated using different indices Raeqwhich is the radium equivalent activity is the most widelyused radiation hazard index [34 35] Raeq is the weightedsum of activities of the three radionuclides based on thesupposition that 370 Bq kgminus1 226Ra 259 Bq kgminus1 232Th and481 Bq kgminus1 40K produce the same gamma-ray dose rate [36]Raeq is given by [37]
where 119862Ra 119862Th and 119862K are the activity concentrations of226Ra 232Th and 40K (in Bq kgminus1) respectively
To keep the annual radiation dose below 15mGy yminus1 themaximum value must be less than 370 Bq kgminus1 [8]
As shown in Table 5 Raeq of agricultural soil sampleswas within the range of 27475ndash81986 Bq kgminus1 with a meanvalue of 458785 Bq kgminus1 which exceeds the permissiblelimit (370 Bq kgminus1) recommended by the Organization forEconomic Cooperation and Development [38] The mean ofRaeq in the virgin soil was found to be 214293 Bq kg
minus1 whichis within the permissible limit
The Scientific World Journal 5
Table 3 The mean activity concentrations of natural radioactivity of agriculture and virgin soils in the present study were compared withthose from similar investigations performed in other countries
RegioncountryConcentration in soil (Bq kgminus1)
Reference226Ra 232Th 40KMean Range Mean Range Mean Range
Virgin soilMalaysia (Penang) 396 165 835 Almayahi et al [5]Malaysia (Pontian) 37 53 293 Saleh et al [6]Malaysia (Kedah) 5106 7844 12566 Ahmad et al [7]Malaysia 6524 4511ndash1114 8339 5183ndash12735 13698 992ndash1728 The present study
Agriculture soilMalaysia (Kedah) 8063 11687 20066 Ahmad et al [7]India 64 93 124 Singh et al [8]Pakistan 30 56 602 Tufail et al [9]Algeria 532 5003 311 Boukhenfouf and Boucenna [10]Egypt 43 57ndash140 54 9ndash139 183 22ndash319 Issa [11]Thailand 43 11ndash78 51 7ndash120 230 7ndash712 UNSCEAR [2]Malaysia 66 49ndash86 82 63ndash110 310 170ndash430 UNSCEAR [2]Greece 16 plusmn 6 12ndash26 55 plusmn 14 39ndash72 305 plusmn 59 222ndash376 Ioannides et al [12]Malaysia 10208 plusmn 396 5893ndash16655 13396 8798ndash18045 32587 2022ndash52917 The present study
The permissible limit of Raeq in building materials mustbe lt370 Bq kgminus1 which is equal to an annual dose of15mSv yminus1 [39 40]
322 Absorbed Dose Rate in Air (D) According to theguidelines provided by UNSCEAR [2] the absorbed gammadose rate 119863119877 (nGy hminus1) in air was determined at 1m abovethe ground surface to ensure uniformdistribution of radionu-clides This parameter can be used to assess any radiologicalhazard and radiation exposure from radionuclides in the soilthe absorbed dose rate was calculated using the followingformula [41]
where 119863119877 is the dose rate in nGy hminus1 and 119862Ra 119862Th and 119862Kare the activity concentrations (Bq kgminus1) of radium (226Ra)thorium (232Th) and potassium (40K) respectively
The absorbed dose rate indicates the received dose out-doors from radiation emitted by radionuclides in environ-mental materials Determination of this rate is the main stepfor evaluating health risk and this parameter is expressed ingray
Table 5 shows the absorbed dose rate calculated fromthe radioactivity concentrations of 226Ra 232Th and 40K inagricultural and virgin soil samples
The absorbed dose rate in agricultural soil ranged from9134 nGy hminus1 to 20734 nGy hminus1 with a mean value of14162 nGy hminus1 which is higher than the global mean valueof 60 nGy hminus1 established by UNSCEAR [2]
The average value of the absorbed dose rate 119863 (nGy hminus1)of agricultural soils in the present study is higher than thosereported in other countries (Table 6) The absorbed gamma
dose rate in virgin soil samples ranged from 6071 nGy hminus1 to12904 nGy hminus1 with an average value of 8747 nGy hminus1 whichis higher than the mean values reported in United StatesJapan Egypt Poland and Switzerland (Table 7) and the valuerecommended by UNSCEAR [2]
323 The Annual Effective Dose Rate Annual effective doseshould be calculated to assess the health effects of theabsorbed dose by using a conversion coefficient (07 SvGyminus1)to transform absorbed dose in air to the effective dosereceived by humans with an outdoor occupancy factor (02)which is equivalent to an outdoor occupancy of 20 and 80for the indoors [38 42]This factor is suitable for determiningthe pattern of life in the studied area Annual effective doserate (AEDR in mSv yminus1) received by the population can becalculated using [43 44]
Annual effective dose rate (mSv yminus1)
= Absorbed dose (nGy hminus1) times 8760 h sdot yrminus1 times 07
times (103mSv10minus9) times 02 (nGyminus1)
= 119863 times 12264 times 10minus3 (mSv yminus1)
(4)
where 119863 (nGh) is the total air absorbed dose rate in theoutdoors 8760 h is the number of hours in one year 02 isthe outdoor occupancy factor 07 SvGyminus1 is the conversioncoefficient fromabsorbed dose in air to effective dose receivedby adults 10minus6 is the conversion factor between nano- andmillimeasurements
The estimated annual effective dose in the agriculturalsoil samples ranged from 0112mSv yminus1 to 0254mSv yminus1 with
6 The Scientific World Journal
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Table 2 The activity concentrations of 226Ra 232Th and 40K (Bq kgminus1) in agricultural and virgin soil samples collected from Kedah soil ofnorth Malaysia
Sample number Activity concentrations (Bq kgminus1) 119863(nGy hminus1)
of 238U 226Ra 232Th and 226Ra decay products this phe-nomenon results in the high activity of 40K in soil [30]
High radioactivity concentrations in the soil of thepresent studied area were also reported in previous studiesby Ahmad et al [7 31] but were lower than those of 226Ra232Th and 40K reported by Almayahi et al [5] and Ahmadet al [7 31] as well as by Saleh et al [6] in virgin soil samples
Themean radioactivity concentrations of 232Thand 226Rain virgin soil in the present study are higher than thosereported by UNSCEAR [2] (Table 7) whereas themean valueof 40K is slightly lower than that reported worldwide exceptfor Japan and Egypt
Variations in the radioactivity concentrations in soils ofvarious locations worldwide depend on the geographical andgeological conditions of the zone and the extent of fertilizerutilized in farmland [32 33]
32 Radiological Hazard Assessment
321 Assessment of Radium Equivalent (119877119886119890119902) Gamma-rayradiation hazards caused by specific radionuclides of 226Ra
232Th and 40K were evaluated using different indices Raeqwhich is the radium equivalent activity is the most widelyused radiation hazard index [34 35] Raeq is the weightedsum of activities of the three radionuclides based on thesupposition that 370 Bq kgminus1 226Ra 259 Bq kgminus1 232Th and481 Bq kgminus1 40K produce the same gamma-ray dose rate [36]Raeq is given by [37]
where 119862Ra 119862Th and 119862K are the activity concentrations of226Ra 232Th and 40K (in Bq kgminus1) respectively
To keep the annual radiation dose below 15mGy yminus1 themaximum value must be less than 370 Bq kgminus1 [8]
As shown in Table 5 Raeq of agricultural soil sampleswas within the range of 27475ndash81986 Bq kgminus1 with a meanvalue of 458785 Bq kgminus1 which exceeds the permissiblelimit (370 Bq kgminus1) recommended by the Organization forEconomic Cooperation and Development [38] The mean ofRaeq in the virgin soil was found to be 214293 Bq kg
minus1 whichis within the permissible limit
The Scientific World Journal 5
Table 3 The mean activity concentrations of natural radioactivity of agriculture and virgin soils in the present study were compared withthose from similar investigations performed in other countries
RegioncountryConcentration in soil (Bq kgminus1)
Reference226Ra 232Th 40KMean Range Mean Range Mean Range
Virgin soilMalaysia (Penang) 396 165 835 Almayahi et al [5]Malaysia (Pontian) 37 53 293 Saleh et al [6]Malaysia (Kedah) 5106 7844 12566 Ahmad et al [7]Malaysia 6524 4511ndash1114 8339 5183ndash12735 13698 992ndash1728 The present study
Agriculture soilMalaysia (Kedah) 8063 11687 20066 Ahmad et al [7]India 64 93 124 Singh et al [8]Pakistan 30 56 602 Tufail et al [9]Algeria 532 5003 311 Boukhenfouf and Boucenna [10]Egypt 43 57ndash140 54 9ndash139 183 22ndash319 Issa [11]Thailand 43 11ndash78 51 7ndash120 230 7ndash712 UNSCEAR [2]Malaysia 66 49ndash86 82 63ndash110 310 170ndash430 UNSCEAR [2]Greece 16 plusmn 6 12ndash26 55 plusmn 14 39ndash72 305 plusmn 59 222ndash376 Ioannides et al [12]Malaysia 10208 plusmn 396 5893ndash16655 13396 8798ndash18045 32587 2022ndash52917 The present study
The permissible limit of Raeq in building materials mustbe lt370 Bq kgminus1 which is equal to an annual dose of15mSv yminus1 [39 40]
322 Absorbed Dose Rate in Air (D) According to theguidelines provided by UNSCEAR [2] the absorbed gammadose rate 119863119877 (nGy hminus1) in air was determined at 1m abovethe ground surface to ensure uniformdistribution of radionu-clides This parameter can be used to assess any radiologicalhazard and radiation exposure from radionuclides in the soilthe absorbed dose rate was calculated using the followingformula [41]
where 119863119877 is the dose rate in nGy hminus1 and 119862Ra 119862Th and 119862Kare the activity concentrations (Bq kgminus1) of radium (226Ra)thorium (232Th) and potassium (40K) respectively
The absorbed dose rate indicates the received dose out-doors from radiation emitted by radionuclides in environ-mental materials Determination of this rate is the main stepfor evaluating health risk and this parameter is expressed ingray
Table 5 shows the absorbed dose rate calculated fromthe radioactivity concentrations of 226Ra 232Th and 40K inagricultural and virgin soil samples
The absorbed dose rate in agricultural soil ranged from9134 nGy hminus1 to 20734 nGy hminus1 with a mean value of14162 nGy hminus1 which is higher than the global mean valueof 60 nGy hminus1 established by UNSCEAR [2]
The average value of the absorbed dose rate 119863 (nGy hminus1)of agricultural soils in the present study is higher than thosereported in other countries (Table 6) The absorbed gamma
dose rate in virgin soil samples ranged from 6071 nGy hminus1 to12904 nGy hminus1 with an average value of 8747 nGy hminus1 whichis higher than the mean values reported in United StatesJapan Egypt Poland and Switzerland (Table 7) and the valuerecommended by UNSCEAR [2]
323 The Annual Effective Dose Rate Annual effective doseshould be calculated to assess the health effects of theabsorbed dose by using a conversion coefficient (07 SvGyminus1)to transform absorbed dose in air to the effective dosereceived by humans with an outdoor occupancy factor (02)which is equivalent to an outdoor occupancy of 20 and 80for the indoors [38 42]This factor is suitable for determiningthe pattern of life in the studied area Annual effective doserate (AEDR in mSv yminus1) received by the population can becalculated using [43 44]
Annual effective dose rate (mSv yminus1)
= Absorbed dose (nGy hminus1) times 8760 h sdot yrminus1 times 07
times (103mSv10minus9) times 02 (nGyminus1)
= 119863 times 12264 times 10minus3 (mSv yminus1)
(4)
where 119863 (nGh) is the total air absorbed dose rate in theoutdoors 8760 h is the number of hours in one year 02 isthe outdoor occupancy factor 07 SvGyminus1 is the conversioncoefficient fromabsorbed dose in air to effective dose receivedby adults 10minus6 is the conversion factor between nano- andmillimeasurements
The estimated annual effective dose in the agriculturalsoil samples ranged from 0112mSv yminus1 to 0254mSv yminus1 with
6 The Scientific World Journal
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Table 3 The mean activity concentrations of natural radioactivity of agriculture and virgin soils in the present study were compared withthose from similar investigations performed in other countries
RegioncountryConcentration in soil (Bq kgminus1)
Reference226Ra 232Th 40KMean Range Mean Range Mean Range
Virgin soilMalaysia (Penang) 396 165 835 Almayahi et al [5]Malaysia (Pontian) 37 53 293 Saleh et al [6]Malaysia (Kedah) 5106 7844 12566 Ahmad et al [7]Malaysia 6524 4511ndash1114 8339 5183ndash12735 13698 992ndash1728 The present study
Agriculture soilMalaysia (Kedah) 8063 11687 20066 Ahmad et al [7]India 64 93 124 Singh et al [8]Pakistan 30 56 602 Tufail et al [9]Algeria 532 5003 311 Boukhenfouf and Boucenna [10]Egypt 43 57ndash140 54 9ndash139 183 22ndash319 Issa [11]Thailand 43 11ndash78 51 7ndash120 230 7ndash712 UNSCEAR [2]Malaysia 66 49ndash86 82 63ndash110 310 170ndash430 UNSCEAR [2]Greece 16 plusmn 6 12ndash26 55 plusmn 14 39ndash72 305 plusmn 59 222ndash376 Ioannides et al [12]Malaysia 10208 plusmn 396 5893ndash16655 13396 8798ndash18045 32587 2022ndash52917 The present study
The permissible limit of Raeq in building materials mustbe lt370 Bq kgminus1 which is equal to an annual dose of15mSv yminus1 [39 40]
322 Absorbed Dose Rate in Air (D) According to theguidelines provided by UNSCEAR [2] the absorbed gammadose rate 119863119877 (nGy hminus1) in air was determined at 1m abovethe ground surface to ensure uniformdistribution of radionu-clides This parameter can be used to assess any radiologicalhazard and radiation exposure from radionuclides in the soilthe absorbed dose rate was calculated using the followingformula [41]
where 119863119877 is the dose rate in nGy hminus1 and 119862Ra 119862Th and 119862Kare the activity concentrations (Bq kgminus1) of radium (226Ra)thorium (232Th) and potassium (40K) respectively
The absorbed dose rate indicates the received dose out-doors from radiation emitted by radionuclides in environ-mental materials Determination of this rate is the main stepfor evaluating health risk and this parameter is expressed ingray
Table 5 shows the absorbed dose rate calculated fromthe radioactivity concentrations of 226Ra 232Th and 40K inagricultural and virgin soil samples
The absorbed dose rate in agricultural soil ranged from9134 nGy hminus1 to 20734 nGy hminus1 with a mean value of14162 nGy hminus1 which is higher than the global mean valueof 60 nGy hminus1 established by UNSCEAR [2]
The average value of the absorbed dose rate 119863 (nGy hminus1)of agricultural soils in the present study is higher than thosereported in other countries (Table 6) The absorbed gamma
dose rate in virgin soil samples ranged from 6071 nGy hminus1 to12904 nGy hminus1 with an average value of 8747 nGy hminus1 whichis higher than the mean values reported in United StatesJapan Egypt Poland and Switzerland (Table 7) and the valuerecommended by UNSCEAR [2]
323 The Annual Effective Dose Rate Annual effective doseshould be calculated to assess the health effects of theabsorbed dose by using a conversion coefficient (07 SvGyminus1)to transform absorbed dose in air to the effective dosereceived by humans with an outdoor occupancy factor (02)which is equivalent to an outdoor occupancy of 20 and 80for the indoors [38 42]This factor is suitable for determiningthe pattern of life in the studied area Annual effective doserate (AEDR in mSv yminus1) received by the population can becalculated using [43 44]
Annual effective dose rate (mSv yminus1)
= Absorbed dose (nGy hminus1) times 8760 h sdot yrminus1 times 07
times (103mSv10minus9) times 02 (nGyminus1)
= 119863 times 12264 times 10minus3 (mSv yminus1)
(4)
where 119863 (nGh) is the total air absorbed dose rate in theoutdoors 8760 h is the number of hours in one year 02 isthe outdoor occupancy factor 07 SvGyminus1 is the conversioncoefficient fromabsorbed dose in air to effective dose receivedby adults 10minus6 is the conversion factor between nano- andmillimeasurements
The estimated annual effective dose in the agriculturalsoil samples ranged from 0112mSv yminus1 to 0254mSv yminus1 with
6 The Scientific World Journal
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Table 4 Gamma-index (119868120574) values proposed by the European Commission (1999) taking in to account typical way and amounts in whichthe material is used in a building [13]
Dose criterion 03mSv yminus1 1mSv yminus1
Materials used in bulk amounts 119868120574 le 05 119868120574 le 1For example bricks superficial and other materialswith restricted use tiles boards and so forth 119868120574 le 2 119868120574 le 6
an average value of 0169mSv yminus1 whereas that for virginsoil samples ranged from0073mSv yminus1 to 0158mSv yminus1 withan average value of 0106mSv yminus1 As shown in (Table 5)the worldwide average annual effective dose is approximately05mSv yminus1 [2] Thus the present average annual effectivedose rates are within the average values reported worldwide
Indoor dose rates were not evaluated because data onaverage buildup of radon gas in the indoor atmosphere werenot available
324 External Hazard Index (119867119890119909) The external hazardindex for samples under investigation was calculated usingthe equation defined by [33]
where 119862Ra 119862Th and 119862K are the activity concentrationsof 226Ra 232Th and 40K in (Bq kgminus1) respectively Themaximum value of 119867ex equal to unity corresponds to theupper limit of Raeq (370 Bq kg
minus1)The calculated values of119867ex for agricultural soil samples
ranged from 0552 to 1252 with a mean value 0859 whereasthose for virgin soil samples ranged from 0362 to 0789 withan average value 0525 (Table 5) The value of 119867ex must belower than unity to keep the radiation hazard insignificantThese values are less than the limit (119867ex less than or equal toone) established by the European Commission on RadiationProtection (1999) [13] hence terrestrial soils from the studyarea present low radiation exposure for people and can beused as a constructionmaterial without posing any significantradiological threat to the general population
325 Gamma Index (119868120574) Gamma index (119868120574) proposed by theEuropean Commission has been calculated from the activityconcentrations of 226Ra 232Th and 40K in soil samples usingthe following formula [13]
where 119860Ra 119860Th and 119860K are the activity concentrations(Bq kgminus1) of radium (226Ra) thorium (232Th) and potassium(40K) respectively
Values of index 119868120574 le 2 correspond to an absorbedgamma dose rate of 03mSvyear whereas 2 lt 120574 le 6corresponds to an absorbed gamma dose rate of 1mSvyear[13 45] andmaterials with 119868120574 gt 6 correspond to
dose rates higher than 1mSvyear which is the high-est dose rate value recommended for the population[13]
Therefore the annual effective dose that can be deliv-ered by the soil as building materials in this study islower than the annual effective dose constraint of 1mSvyear
The calculated values of agricultural and virgin soilsamples are presented in Tables 2 and 5 gamma indices ofagricultural soil are varying from 07 to 16 with amean valueof one that is found to be higher than the limit of 05 whilethose found in the virgin soils are varying from 04 to 1 witha mean value of 059 It is observed that the mean values ofagricultural and virgin soils did not exceed the recommendedupper limit (Table 4) Therefore the annual effective dosethat can be delivered by the soil as building materials in thisstudy is lower than the annual effective dose constraint of1mSvyear
Moreover the gamma-index values of our study arecomparable with results of various studies around the world(Table 6)
4 Conclusion
Gamma spectrometry was used to measure the radioactivityconcentration of 30 agricultural and virgin soil samples col-lected fromKedah Region north ofMalaysia Results showedthat the mean activity concentrations of 226Ra 232Th and 40Kare 10208 plusmn 396 13396 plusmn 292 and 32587 plusmn 983 Bq kgminus1respectively in agricultural soil samples and 6524 plusmn 2008339 plusmn 227 and 13698 plusmn 976 Bq kgminus1 in virgin soil samplesThe measured values are higher than those reported inother soils worldwide The average activity concentrationsof 226Ra and 232Th (Bq kgminus1) in virgin and agricultural soilsare higher than the world recommended values UNSCEAR[2] However the average activity concentration of 40K isbelow the recommended values in both soil types No 137Csactivity concentration was found in any of the samples fromthis district indicating the absence of artificial radionuclidefallout from any nuclear accidents
The mean value of gamma absorbed dose in air outdoorsare within the range of 9134ndash20734 nGy hminus1 with a meanvalue of 14162 nGy hminus1 for agricultural soils and within6071ndash12904 nGy hminus1 with an average of 8747 nGy hminus1in virgin soil these values are higher than the globalaverage value of 60 nGy hminus1 UNSCEAR [2] in both soiltypes
The Scientific World Journal 7
Table 5 Range and mean value of activity concentrations of 226Ra 232Th and 40K (in Bq kgminus1) Ra equivalent Raeq (Bq kgminus1) absorbed dose
rates119863 (nGy hminus1) external hazard index (119867ex) annual effective dose rates AEDE (mSv yminus1) in soil samples of Kedah
Sample Mean Maximum MinimumRadionuclides226Ra Agricultural soil 10208 plusmn 396 16655 plusmn 666 5893 plusmn 180
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Gamma index 119868120574Agricultural soil 107 162 07
Virgin soil 059 1 04
Table 6 Average hazard indices of the primordial radionuclides in the worldwide agricultural soils
Location 119863 (nGyh) 119863eff (mSvy) 119867ex 119868120574 ReferenceVietnam 7172 054 043 mdash Huy et al [14]India 9747 012 mdash Mehra and Singh [15]Saudi Arabia 233 014 013 mdash Alaamer [16]Malaysia 20204 023 119 mdash Musa et al [17]Jordan 5150 006 028 mdash Al-Hamarneh and Awadallah [18]Pakistan 6883 034 039 014 Rafique et al [19]India 901 011 053 071 Zubair et al [20]Egypt (Rashid) 11836 14516 040 052 EL-Kameesy et al [21]India (Karnataka State) 3323 407 019 029 Chandrashekara et al [22]Malaysia 14162 0169 0859 mdash Present studyWorldwide 60 0070 1 mdash UNSCEAR [2]
The average annual effective dosages from agriculturaland virgin soil samples are also lower than the global averagevalues
The value of Raeq activity concentrations for agricul-tural and virgin soil samples is less than 370 Bq kgminus1 withthe mean value exceeding the permissible limit recom-mended by the Organization for Economic Cooperation andDevelopment (NEA-OECD report) [38] in agriculture soilsamples
The mean value of the external hazard index 119867ex ofthe study area is found to be within the recommended safelevels (119867ex less than or equal to one) The obtained results ofgamma index (119868120574) are within the recommended safety limitsof European Commission (1999)
This study established a map of baseline information forfuture studies on radiation levels and radionuclide distribu-tion in the environment of Kedah The results of the studyserve as a reference for future assessment
Competing Interests
The authors declare that they have no competing interests
Acknowledgments
This work is supported by University of Malaya by HighImpact Research Grant H-21001-F0033 and PostgraduateResearch Fund PG065-2013A
8 The Scientific World Journal
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Table 7 Comparison of natural radioactivity levelsmeasured in soil in the present studywith the values reported in other countriesworldwideand established by UNSCEAR [2]
RegioncountryConcentration in soil (Bq kgminus1) Absorbed dose rates
in air (nGy hminus1)226Ra 232Th 40KMean Range Mean Range Mean Range Mean Range
[1] A P Radhakrishna H M Somashekarappa Y Narayana andK Siddappa ldquoA new natural background radiation area on thesouthwest coast of indiardquoHealth Physics vol 65 no 4 pp 390ndash395 1993
[2] United Nations Scientific Committee on the Effects of AtomicRadiation ldquoSources and Effects of Ionizing RadiationrdquoUNSCEAR 2000 Report Vol1 to the General Assembly withscientific annexes United Nations Sales Publication UnitedNations New York 2000
[3] B Skwarzec and L Falkowski ldquoAccumulation of 210Po in Balticinvertebratesrdquo Journal of Environmental Radioactivity vol 8 no2 pp 99ndash109 1988
[4] J Al-Jundi B A Al-Bataina Y Abu-Rukah and H M She-hadeh ldquoNatural radioactivity concentrations in soil samplesalong the AmmanAqabaHighway JordanrdquoRadiationMeasure-ments vol 36 no 1ndash6 pp 555ndash560 2003
[5] B A Almayahi A A Tajuddin and M S Jaafar ldquoRadiationhazard indices of soil and water samples in NorthernMalaysianPeninsulardquo Applied Radiation and Isotopes vol 70 no 11 pp2652ndash2660 2012
[6] M A Saleh A T Ramli Y Alajerami and A S AliyuldquoAssessment of natural radiation levels and associated dose ratesfrom surface soils in Pontian district Johor Malaysiardquo Journalof Ovonic Research vol 9 no 1 pp 17ndash27 2013
[7] N Ahmad M Jaafar and M Alsaffar ldquoNatural radioactivity invirgin and agricultural soil and its environmental implicationsin Sungai Petani Kedah Malaysiardquo Pollution vol 1 no 3 pp305ndash313 2015
[8] S Singh A Rani and R K Mahajan ldquo226Ra 232Th and40K analysis in soil samples from some areas of Punjab and
Himachal Pradesh India using gamma ray spectrometryrdquoRadiation Measurements vol 39 no 4 pp 431ndash439 2005
[9] MTufail NAkhtar andMWaqas ldquoMeasurement of terrestrialradiation for assessment of gamma dose from cultivated andbarren saline soils of Faisalabad in Pakistanrdquo Radiation Mea-surements vol 41 no 4 pp 443ndash451 2006
[10] W Boukhenfouf and A Boucenna ldquoThe radioactivity mea-surements in soils and fertilizers using gamma spectrometrytechniquerdquo Journal of Environmental Radioactivity vol 102 no4 pp 336ndash339 2011
[11] S A M Issa ldquoRadiometric assessment of natural radioactivitylevels of agricultural soil samples collected in Dakahlia EgyptrdquoRadiation Protection Dosimetry vol 156 no 1 pp 59ndash67 2013
[12] K G Ioannides T J Mertzimekis C A Papachristodoulouand C E Tzialla ldquoMeasurements of natural radioactivity inphosphate fertilizersrdquo Science of the Total Environment vol 196no 1 pp 63ndash67 1997
[13] European Commission Radiation Protection ldquoRadiologicalprotection principles concerning the natural radioactivity ofbuilding materialsrdquo Brussels Report 112 European Commis-sion 1999
[14] N Q Huy P D Hien T V Luyen et al ldquoNatural radioactivityand external dose assessment of surface soils in VietnamrdquoRadiation ProtectionDosimetry vol 151 no 3 pp 522ndash531 2012
[15] RMehra andM Singh ldquoMeasurement of radioactivity of 238U226 Ra 232Th and 40K in soil of different geological origins inNorthern Indiardquo Journal of Environmental Protection vol 2 no7 p 960 2011
[16] A S Alaamer ldquoAssessment of human exposures to naturalsources of radiation in soil of Riyadh Saudi Arabiardquo Turkish
The Scientific World Journal 9
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
Journal of Engineering and Environmental Sciences vol 32 no4 pp 229ndash234 2008
[17] M Musa Z Hamzah and A Saat ldquoMeasurement of naturalradionuclides in the soil of Highlands agricultural farmlandrdquo inProceedings of the 3rd International Symposium and Exhibitionin Sustainable Energy andEnvironment (ISESEE rsquo11) pp 172ndash176IEEE Melaka Malaysia June 2011
[18] I F Al-Hamarneh andM I Awadallah ldquoSoil radioactivity levelsand radiation hazard assessment in the highlands of northernJordanrdquo Radiation Measurements vol 44 no 1 pp 102ndash1102009
[19] M Rafique H Rehman M Matiullah et al ldquoAssessment ofradiological hazards due to soil and building materials used inMirpur Azad Kashmir Pakistanrdquo Iranian Journal of RadiationResearch vol 9 no 2 pp 77ndash87 2011
[20] M Zubair D Verma A Azam and S Roy ldquoNatural radioactiv-ity and radiological hazard assessment of soil using gamma-rayspectrometryrdquo Radiation Protection Dosimetry vol 155 no 4pp 467ndash473 2013
[21] S U EL-Kameesy S A EL-Fiki M S Talaat et al ldquoRadioac-tivity levels and hazards of soil and sediment samples collectedfrom Damietta and Rashid branches of the River Nile EgyptrdquoGlobal Journal of Physics vol 4 no 1 2016
[22] M S Chandrashekara K M Nagaraju K S Pruthvi Raniand L Paramesh ldquoNatural radionuclide in soil samples andradiation dose to the population of Chamarajanagar districtKarnataka State Indiardquo International Journal of Advanced Sci-entific and Technical Research vol 4 no 4 pp 466ndash474 2014
[23] A El-Taher and S Makhluf ldquoNatural radioactivity levels inphosphate fertilizer and its environmental implications inAssuit governorate upper Egyptrdquo Indian Journal of Pure andApplied Physics vol 48 no 10 pp 697ndash702 2010
[24] A Guidebook Measurement of Radionuclides in Food and theEnvironment International Atomic Energy Agency IAEAViennaAustria 1989httpwww-pubiaeaorgMTCDPublicationsPDFtrs295 webpdf
[25] NM IbrahiemAHAbdElGhani SM Shawky EMAshrafand M A Farouk ldquoMeasurement of radioactivity levels in soilin the nile delta and middle egyptrdquo Health Physics vol 64 no6 pp 620ndash627 1993
[26] A S Mollah M M Rahman and M A Koddus ldquoMeasure-ment of high natural background radiation levels by TLD atCoxrsquos Bazar coastal areas in Bangladeshrdquo Radiation ProtectionDosimetry vol 18 no 1 pp 39ndash41 1987
[27] NAkhtarMTufailMAshraf andMM Iqbal ldquoMeasurementof environmental radioactivity for estimation of radiationexposure from saline soil of Lahore Pakistanrdquo Radiation Mea-surements vol 39 no 1 pp 11ndash14 2005
[28] C E Pereira V K Vaidyan A Sunil S Ben Byju R M Joseand P J Jojo ldquoRadiological assessment of cement and clay basedbuilding materials from southern coastal region of KeralardquoIndian Journal of Pure amp Applied Physics vol 49 no 6 pp 372ndash376 2011
[29] N Ibrahim ldquoNatural activities of 238U 232Thand 40K in buildingmaterialsrdquo Journal of Environmental Radioactivity vol 43 no 3pp 255ndash258 1999
[30] J I Skorovarov V V Shatalov V I Nikonov andV Y SmironovldquoPreservation of environment as basic principle in uranium oreprocessing technologyrdquo
[31] N Ahmad M S Jaafar M Bakhash and M RahimldquoAn overview on measurements of natural radioactivity in
Malaysiardquo Journal of Radiation Research and Applied Sciencesvol 8 no 1 pp 136ndash141 2015
[32] National Council on Radiation Protection and MeasurementsldquoNatural Background Radiation in the United statesrdquo NCRPReport 45 National Council on Radiation Protection andMeasurements Bethesda Md USA 1975
[33] A El-Taher ldquoINAA and DNAA for uranium determination ingeological samples from EgyptrdquoApplied Radiation and Isotopesvol 68 no 6 pp 1189ndash1192 2010
[34] J Beretka and P J Mathew ldquoNatural radioactivity of australianbuilding materials industrial wastes and by-productsrdquo HealthPhysics vol 48 no 1 pp 87ndash95 1985
[35] R Krieger ldquoRadioactivity of constructionmaterialsrdquo Betonwerkund Fertigteil-Technik vol 47 no 8 pp 468ndash446 1981
[36] P Kessaratikoon and S Awaekechi ldquoNatural radioactivity mea-surement in soil samples collected from municipal area of HatYai district in Songkhla provinceThailandrdquoKMITL Science andTechnology Journal A vol 8 no 2 pp 52ndash58 2008
[37] E R L I N G Stranden ldquoSome aspects on radioactivity ofbuilding materialsrdquo Physica Norvegica vol 8 no 3 pp 163ndash1671976
[38] OECD ldquoExposure to radiation from the natural radioactivity inbuilding materialsrdquo Report by a Group of Experts of the OECDNuclear Energy Agency Paris France 1979
[39] UNSCEAR Ionizing Radiation Sources and Biological EffectsUnited Nations Scientific Committee on the Effects of AtomicRadiation Report to General Assembly with Annexes UnitedNations New York NY USA 1982
[40] Organization for Economic Cooperation and DevelopmentExposure to radiation from the natural radioactivity in buildingmaterials (OECD Paris) Report by a Group of Experts of theOECD Nuclear Energy Agency 1979
[41] R Veiga N Sanches R M Anjos et al ldquoMeasurement ofnatural radioactivity in Brazilian beach sandsrdquo Radiation Mea-surements vol 41 no 2 pp 189ndash196 2006
[42] United Nations Scientific Committee on the Effects of AtomicRadiation (UNSCEAR) Ionizing Radiation Sources and Effectsof IonizingRadiation UnitedNationsNewYorkNYUSA 1993
[43] UNSCEAR Source and Effects of Ionizing Radiation Report tothe General Assembly United Nations New York NY USA1988
[44] U Cevik N Damla B Koz and S Kaya ldquoRadiological charac-terization around the Afsin-Elbistan coal-fired power plant inTurkeyrdquo Energy amp Fuels vol 22 no 1 pp 428ndash432 2008
[45] EC (European Commission) Radiological Protection PrinciplesConcerning the Natural Radioactivity of Building MaterialsRadiation Protection 112 [PhD thesis] General EnvironmentNuclear Safety and Civil Protection Luxembourg Belgium2000
![Risks from naturally occurring radionuclides in the Nordic ...¸d.pdf · radiation Other radionuclides in air [KATEGORINA VN] [KATEGORINA VN] Anthropogenic radionuclides in diet Average](https://static.documents.pub/doc/80x56/5f8a90afcd79846e8d420ef0/risks-from-naturally-occurring-radionuclides-in-the-nordic-dpdf-radiation.jpg)
