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* To whom all correspondence should be addressed. +27 16 430 8463;

e-mail: [email protected] Received 25 July 2011; accepted in revised form 9 July 2012.

Implementing a protocol for selection and prioritisation

of organic contaminants in the drinking water value chain:

Case study of Rand Water, South Africa

EJ Ncube1,2*, K Voyi2 and H du Preez1,31Rand Water, Scientic Services Division, PO Box 1170, Johannesburg, 2000, South Africa

2School of Health Systems and Public Health, Faculty of Health Sciences, University of Pretoria, Pretoria, 0002, South Africa3Department of Zoology, University of Johannesburg, PO Box 17011, Johannesburg 2028, South Africa

Abstract

Approaches that prioritise chemicals according to their importance as environmental contaminants have been developedby government agencies and private indust ries. However, it has been noticed that few approaches, such as one publishedby the United States Environmental Protect ion Agency (USEPA), address the needs of the dr inking water indust ry. Thereis also no generic approach to the selection, prioritisation and monitoring of organic contaminants in the drinking watervalue chain. To safeguard drinking water industry customers, it was necessary to develop a generic protocol to assist withthe identication of a list of organic contaminants for monitoring in the drinking water value chain. Once the protocol wasdeveloped, it was validated in a prototype drinking water value chain. This paper describes the implementation of such a

generic protocol. The exercise comprised of testing each step of the protocol, from selection of the pool of organic contami-nants (Step I) to recommending the nal priority list of organic contaminants (Step VII). Successful implementation of theprotocol took place in the Rand Water (South Africa) drinking water value chain (from catchment to tap). Expert judgmentwas emphasized during the implementation as each step was validated and the opinion of key stakeholders used to shape theprocess. The tailor-made prioritisat ion criter ia, reect ing the drinking water indust ry perspective, proved to be successfulin selecting and prioritising organic contaminants for monitoring in the dr inking water value chain. The organic contami-nants were successfully prioritised in 3 classes: short-term priority for analysis, medium-term priority for analysis andlong-term priority for analysis. This is a very important guide to assist water utilities in optimising their resources while notcompromising the role of public health protection. Finally, a priority list of organic contaminants was identied for use byRand Water and other water utilities.

Keywords: generic protocol, organic contaminants, validation, selection and prioritisation, drinking watervalue chain, expert judgment

Introduction

Todays vast chemical industry and particularly its giantoffspring, the production of synthetic organic chemicals(Middleton and Rosen, 1956), have introduced new challengesto the scientists and public ofcers engaged in providing andprotecting public health through the provision of safe drink-ing water. This challenge was noticed more than half a centuryago (Middleton and Rosen, 1956). Industrial contaminationof water, while important, is not the only factor to considerin the complex organic pollution situation. Domestic sewage,natural run-off and materials derived from the life cycle ofaquatic plants and animals contribute substantial quantities of

organic materials to streams. (Meintjes et al., 2000; Kolpin etal., 2004; Cheevaporn et al., 2005; Voutsa et al., 2006; Ellis,2006) This observation has resulted in recent research effortsbeing focused on organic contaminants (Zimmerman, 2005;Karthikeyan and Meyer, 2006; Rissato et al., 2006; Weber etal., 2006; Rowe et al., 2007; Kim et al., 2007; Kumar et al.,2008). The major outcome from this has been the detection ofa number of more classic organic contaminants as well as the

so-called emerging organic contaminants (Kaj et al., 2005;Colvin, 2006; Richardson et al., 2002; Loganathan et al., 2007;Haukas et al., 2007; Mige et al., 2008; Oberdrster et al.,2006). Another challenge is the indication that most organicwastewater contaminants are not completely removed dur ingconventional wastewater and drinking water production pro-cesses (Rodriguez-Mozaz et al., 2006; Majam and Thompson,2007; Kim et al., 2007; Stackelberg et al., 2007; Mige et al.,2008; Balest et al., 2008; Okuda et al., 2008). Such contami-nants might be present in drinking water distributed to theconsumers and the number of organic contaminants of concernto the drinking water industry has increased.

Exposure of consumers to organic contaminants introduced

during drinking water distribution, either from materials ofconstruction or by process, needs to be assessed since con-sumers might have direct exposure. Such studies have beenconducted (Kolpin et al., 2004; Ellis, 2006; Bolto and Gregory,2007; Majam and Thompson, 2006; Majam and Thompson,2007; Kim et al., 2007; Stackelberg et al., 2007; Mige et al.,2008). It is therefore necessary to identify organic contami-nants with the potential of entering into surface and ground-water sources, being introduced into the treatment process,surviving the treatment process or being formed as impuritiesand/or by-products during the treatment process. This includessubstances released into treated water due to leaching fromdistribution material, such as reservoir linings, pipelines, and/or released from household plumbing systems into the nal
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drinking water. Consumers might also be exposed to organiccontaminants at the point of use through activities such as bath-ing and washing (Cheevaporn et al., 2005).

The concerns of the drinking water industry includepotential adverse health effects these organic contaminantsare capable of causing, potential damage to inf rastructure, andimpairment of the acceptability of drinking water to consum-ers. Among those known are the production of offensive tastesand odours in water (Carmichael et al., 2001; Du Preez and

Van Baalen, 2006), interference with t reatment of water forindustrial and domestic use (Majam and Thompson, 2006), andcausing of adverse health effects to non-target aquatic organ-isms and human health (Calderon, 2000; Cooper et al., 2000;WHO, 2004; Wiegand and Pugmacher, 2005; Rier and Foster,2002; Zhu et al., 2006; Voulvoulis, 2004; Sharpe, 2003; Webbet al., 2003; Jones et al., 2005; Gopal et al., 2007). Well-knownadverse health effects of concern include various cancers,mutagenicity, teratogenicity, reproductive effects, toxicity andendocrine disruption (Burger, 2005). Consequently, monitor-ing for organic contaminants in the dr inking water value chain(from source to tap) is becoming mandatory. It is thereforecrucial that appropriate tools that will allow drinking waterservice providers to manage organic contaminants in the drink-ing water value chain be developed. The tool should allow theservice provider to select and prioritise those priority organiccontaminants of concern to dr inking water and public health.

Approaches that prioritise chemicals according to theirimportance as environmental contaminants have been devel-oped by government agencies and private industries such asthe United Kingdoms Institute for Environmental Health(IEH) (IEH, 2004), the European Communitys Oslo andParis (OSPAR) Convention exercise for the protection of theNortheast Atlantic marine environment (EC, 2000; EAWAG,2002), the European Union (EU)s combined monitoring-basedand modelling-based pr iority-setting scheme (EU-COMMPs)(Klein et al., 1999) and the United States Environmental

Protect ion Agency (USEPA) (USEPA, 2000; EAWAG, 2002;USEPA, 2008). These approaches have illustrated how thecomplex and often contentious task of identifying, rankingand culling multitudes of substances to result in much smallernumbers that will receive regulatory and research considerationhas been approached in various countries. They also serve toillustrate how stakeholder consultation and exper t judgment isvital and integral to the design, implementation and validationof these types of prioritisation schemes. However, shortcom-ings are apparent. Few approaches address the needs of thedrinking water industry and there is no generic approach to theselection, prioritisation and monitoring of organic contami-nants in the drinking water value chain. This has led to poorregulation of organic contaminants in drinking water, espe-

cially in developing countries.To address these shortcomings, Ncube et al., (2011) devel-

oped a generic protocol for the selection and prioritisation oforganic contaminants for monitoring in the drinking watervalue chain (from source to tap) (Fig. 1). This protocol wasimplemented in a prototype drinking water value chain. Theframework within which the protocol was developed consistedof 3 major steps: the selection of the pool of contaminants,screening, and prioritisation. For each step criteria reectiveof the needs of the drinking water industry, being mainly toprotect human health and integrity of the water supplied toconsumers, was used. The protocol aimed to identify prior-ity organic contaminants for monitoring in the drinking watervalue chain (from source to tap). In addition, this protocol

served to identify the importance of expert judgment in thistype of exercise, proposing tailor-made criteria for prioritisingorganic contaminants and challenges faced by the industry inmonitoring for organic contaminants in environmental sam-ples. Hence, the main criteria used were based on the potentialof organic contaminants to occur in the drinking water valuechain, potential to cause human health effects, availability ofstandards and guidelines to allow for the regulation of organiccontaminants in dr inking water, capacity for removal, ease

of monitoring in the drinking water value chain, potential ofcontaminant to cause aesthetic water quality problems such astaste, discolouration and odour, and the potential to increasethe customer perception of risk. The objective of this paper isto present the approach used to prioritise the organic contami-nants, the outcome of implementing each step f rom selectionto prioritisation, and the priority organic contaminants recom-mended for use by a case-study drinking water service pro-vider, Rand Water (South Africa) and other water utilities.

Description of study area

Rand Water is a bulk water supplier which provides treatedwater to more than 12 million people. Rand Waters area ofsupply includes a distribution network of over 3 056 km oflarge diameter pipeline, feeding 58 strategically-located ser-vice reservoirs (Fig. 1). Its customers include metropolitanmunicipalities, local municipalities, mines and industries andit supplies, on average, 3 653 million litres of water to thesecustomers daily. The water utility abstracts its source waterfrom the Vaal Dam catchment. This catchment is mainlyagricultural although other land-use activities such as coalmining, gold mining, fuel production, power-generation, urbanand industrial development also occur. This could result in therelease of organic contaminants into the catchment. A surveyconducted by Bruwer et al. (1985, cited in Braune and Rogers,1987) showed micro-organic contamination along the entire

length of the Vaal River downstream of the Vaal Barrage. Thesurvey also indicated evidence of bio-accumulation of poly-chlorinated biphenyls (PCBs) and chlorinated pesticides insh. Van Steenderen et al. (1987, cited in Braune and Rogers,1987) reported a high degree of organic contamination in theVaal River below the Barrage to Parys. High levels of phenoliccompounds were found. These compounds can cause serioustaste and odour problems, especially after chlorination. VanSteenderen et al. (1987) investigated organic contaminationbetween the Vaal Dam-Vaal River Barrage system. The inves-tigation of organic contaminants between the Grootdraai Damand Parys resulted in 25 organic compounds being identied.These included chlorinated benzenes, phenols, phthalates, satu-rated hydrocarbons, pesticides such as atrazine, -BHC, choles-

terol and polynuclear aromatic hydrocarbons such as pyrene.In the early 1980s, Rand Water did an extensive survey of

all international organic criteria, compiled appropriate docu-ments on the use of organic contaminants in its catchmentsand funded a workshop with a panel of experts in order toestablish the usage of various compounds in South Africa andthe possibility of any detrimental health effects on Rand Waterconsumers (Bailey et al., 1988). It was evident that limitingfactors have been the lack of accurate information about theextent of pollution, lack of capacity and expertise for analysisand the absence of local guidelines and standards for regula-tion of organic contaminants in drinking water. Some of theresearch needs identied for the Vaal River Catchment werethe establishment of an organic pollutant monitoring system,

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factors affecting water quality in the Vaal Dam and the effectsof future management options on water quality and the accu-mulation of pesticides in the aquatic food chain (Braune andRogers, 1987).

These identied research needs and the global actions onpersistent organic pollutants (POPs) and suspected or potentialendocrine-disrupting chemicals (EDCs) have since served as acatalyst for Rand Water management to re-kindle the efforts toaddress concerns of possible drinking water contamination by

organic contaminants. These concerns were held by other roleplayers in the water sector and relevant stakeholders such asthe Department of Water Affairs (DWA), the Water ResearchCommission (WRC), other Water Boards, the Department ofAgriculture, and universities who had started dialogue andresearch in the area. A study by Polder et al. (2008) indicatedthat higher concentrations of polybrominated diphenyl ethers(PBDEs) were measured in bird eggs from the Vaal River,which is situated downstream of the most industrialised area inSouth Africa (Polder et al., 2008). It is because of this contextthat Rand Water was chosen for validation of the protocol forthe selection and prioritisation of organic contaminants formonitoring in the drinking water value chain.

Application of the protocol

This entailed the assessment of all of the steps illustrated inFig. 2. A list-based approach was used in compiling the poolof contaminants. Information, on naturally-occurring organiccontaminants, known classical and emerging organic con-taminants, organic contaminants deliberately added into thedrinking water during its treatment including known watertreatment residues (WTR), restricted, banned and locally-usedpesticides, was collated (Table 1). Four manuals on used pesti-cides and management of pests from the national Departmentof Agriculture were used to identify frequently-used pesticides(DoA, 2000; DoA 2002; DoA, 2003; DoA, 2004). The PAN-UKdatabase for South Africas registered list of pesticides was

used for comparison and conrmation. The lists of regulatedorganic contaminants, such as endocrine-disrupting chemicals(EDCs), the EU list of priority substances for drinking waterused for human consumption and the dir ty dozen identiedby the Stockholm Convention on Persistent Organic Pollutants(UNEP, 2001) were also considered. Organic contaminantsappearing in drinking water quality guidelines or standards,such as the South African National Standard for drinking waterSANS 241 (SABS, 2006), WHO guidelines for drinking water

quality ( WHO, 2004), Health Canada drinking water qualityguidelines (Health Canada, 2008), the USEPA list of regu-lated organic contaminants in drinking water (USEPA, 2008),organic contaminants in the Australian drinking water qualityguidelines (NHMRC, 2004) and the New Zealand drinkingwater quality standards (MoH, 2008), were identied using theWHO guidelines as a benchmark. Interviews were conductedwith various organisations to identify organic contaminantsbeing analysed for. The information gathered from the inter-views was checked against the pool of organic contaminantsor added accordingly. The resultant pool of contaminantscontained 600 organic compounds.

Once the pool of contaminants was compiled, a work-shop was conducted to determine the organic contaminants

of possible concern. This was a qualitative exercisewhere theguiding principle was the relevance of the organic contami-nants and their public health signicance to the drinking waterindustry. During this step, similarities were noted and someorganic contaminants were eliminated from the list basedon the non-relevance to drinking water and the diversity ofviews and experience of the various exper ts. Some organiccontaminants were adopted as being of concern, resulting in aPreliminary list of organic contaminants of possible concern(PLOCPC) (Fig. 2). This resulted in 328 organic contaminantsof possible concern remaining on the list. The screening of thepreliminary list of organic contaminants of possible concernto drinking water was performed at 4 different levels (Fig. 2).This rstly involved conducting a literature survey, as it was

Figure 1

Rand Waters

area of supply in

Gauteng Province

and surrounds (from

Rand Water, 2006)

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Figure 2

A generic protocol for the selection and pr ioritisation for organic contaminants for monitor ing in the drink ing water value chain

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evident that there might be more contaminants of concernto the drinking water industry. The list produced from theliterature review was compared with the Preliminary list oforganic contaminants of possible concern (PLOCPC). Someorganic contaminants were eliminated at this stage based onthe weight of evidence from the literature review. The com-pounds were arranged into a table according to their funct ionalgroups: organic contaminants of health concern via the drink-ing water ingestion route, dermal contact or inhalation, or thoseof aesthetic concern. Any evidence from the literature reviewwas noted accordingly, as this would assist in decision-makingin future steps. The main aim of the literature review was toidentify organic contaminants with the potential for occurringin source water resources, at the plant during water treatment,

along the distribution network and at the point of use.The literature review revealed that organic contaminants

that threaten source water quality include both naturally-occur-ring organic compounds and synthetic organic compounds.Natural organic contaminants include natural organic matter,humic substances, (Coelho-Souza et al., 2006; Frimmel, 1998;Klavin et al., 2001) organometallics, (Pacheco et al., 2005;Leeuwen, 2000; Mahalingam, 2004), algal toxins and theirmicrobial metabolites. Major groups of organic contaminantsfound in the literature were pesticides and their metabolites andpharmaceuticals and personal care products (PPCPs) (Kolpinet al., 2004; Karthikeyan and Meyer, 2006; Ellis, 2006; Kim etal., 2007; Stackelberg et al., 2007). Like the PPCPs, pesticideshave been widely researched (Cheevaporn et al., 2005; Rissato

et al., 2006; Zhang et al., 2004; Zhang et al., 2002; Wenzel etal., 2003). The various groupings of organic contaminants thatoccur in source water resources across the globe, as obtainedfrom the literature review, are presented in Fig. 3.

Organic contaminants from water treatment

processes

While the addition of chemicals to source water during drink-ing water production is benecial, the general concern is theformation of water treatment residues (WTRs). WTRs are by-products f rom drinking water production (Titshall and Hughes,2005). WTRs from conventional water treatment processesconsist mainly of the precipitated hydroxides of the treatment

chemicals that are added to coagulate and occulate dissolvedand suspended material in the source water and also during theresidue dewatering process (Titshall and Hughes, 2005). SomeWTRs of concern include those introduced by the use of syn-thetic organic polymers as coagulant or occulant aids (Boltoand Gregory, 2007; Niquette et al., 2004; Lee et al., 2004).These structures may be polyelectrolytes, such as water-solubleocculants or water insoluble ion exchange resins, or insolubleuncharged materials such as those used for plastic pipes andplastic tr ickling lter media. Polydiallyldimethyl ammoniumchloride (PDADMAC) and epichlorohydrin-dimethylamine(epi-DMA) are established coagulants in the treatment ofdrinking water (Majam and Thompson, 2006). However,polyelectrolyte products used in the water supply industry may

Table 1Information sources for compiling the pool of contaminants

Organisation Information requested Remarks

Other water utilities Organic contaminants currently analysed for indrinking water

BTEX, THMs, DOC, phenols

Department of Agriculture Banned, restricted and frequently-used pesticides inSouth Africa

A set of 4 manuals on pesticidesused in South Africa for variouspurposes was obtained.

Department of Environmental Affairsand Tourism Africa Stockpiles Project implementation in SouthAfrica The dirty dozen

The Department of Water Affairs,National Toxicity MonitoringProgramme

Toxicants monitored in national water resources The dirty dozen

The WHO guidelines for drinkingwater quality, 3rd edition, 2004

Organic contaminants of concern to public health All listed organic contaminants

The PAN-UK list of registered pesti-cides for South Africa

List of currently used, banned, restricted pesticides About 500 pesticides had been reg-istered at the time of the study

SANS 241:2006 List of organic parameters for analysis in drinkingwater

DOC, phenols and THMs

Health Canada List of organic parameters for analysis in drinkingwater

Listed organic contaminants ofconcern

New Zealand List of organic parameters for analysis in d rinkingwater Listed organic contaminants ofconcernIARC List of organic contaminants recognised as human

carcinogensListed organic contaminants ofconcern

USEPA, IRIS database A list of organic compounds for which chronichealth hazard assessments for non-carcinogeniceffects have been done


EU Drinking Water Directive List of organic contaminants for analysis in waterused for human consumption


EDCs for monitoring in drinkingwater (South Africa)

List of EDCs WRC Project KV 143/05

Organic contaminants in the drinking water value chain (from source to tap)

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contain, in addition to polyelectrolyte, measurable amounts ofcertain contaminants. These contaminants are essentially unre-acted raw material from the polyelectrolyte manufacturing pro-cess, for example monomer units, initiators and quenchers. Theliterature review focused on these types of organic contaminants.

Synthetic organic polymer use has resulted in concernsother than those of introducing impurities in parent compoundsresulting in the release of residual monomers and other organic

contaminants of concern into water sys-tems (Bolto and Gregory, 2007; Kurenkovet al., 2003; Majam and Thompson, 2006;Lee et al., 2004; Chang, 2004). Theseinclude degradation of polyelectrolytesinto other organic compounds of concernto human health, serving as precursorsfor the formation of disinfection by-products which have potentially larger

toxic effects on consumers than theirparent compounds (Bolto and Gregory,2007; Kurenkov et al., 2003; Majamand Thompson, 2006; Lee et al., 2004;Chang, 2004). Disinfection by-productsof concern include nitrosodimethylamine(NDMA) (Bolto and Gregory, 2007) anda range of VOCs (Majam and Thompson,2006).

Other organic contaminants formedduring treatment processes include disin-fection by-products (DBPs) of concern tothe health of consumers. There is no doubtthat chlorination has been successfullyused for the control of waterborne infec-tious diseases for more than a century(Gopal et al., 2007). It has been conrmedthat the chemical disinfection of waterresults in the formation of a wide varietyand large number of DBPs (Simmons etal., 2004; Gopal et al., 2007; Richardsonet al., 2002; Woo et al., 2002; Moudgalet al., 2000; Von Gunten, 2003). DBPproles can vary with t reatment methods(Schenck et al., 2004; Gopal et al., 2007).The number, chemical type and concen-tration of DBPs formed depends on source

water characteristics such as: type andconcentration of disinfectant, applicationpoint in the treatment process, type andconcentration of organic matter in thewater, pH, temperature, and contact t imewith the disinfectant (Richardson, 2003).Halogenated trihalomethanes (THMs)and haloacetic acids (HAAs) are twomajor classes of DBPs commonly found inwaters disinfected with chlorine. THMs(the combination of chloroform, bro-modichloromethane, chlorodibromometh-ane and bromoform) and HAA5 (the 5haloacetic acids: monochloro, dichloro-,

trichloro-, monobromo-and dibromoaceticacids) are by-products of chlorination.

Bromate is a by-product of bothdisinfection with ozone and chlorine(Richardson, 2003). The challenge fac-ing water-supply industry professionals

is how to simultaneously minimise the r isk from microbialpathogens and disinfection by-products (Woo et al., 2002).New DBPs are also emerging as organic contaminants ofconcern (Richardson, 2003). Such DBPs include brominatedand iodinated compounds such as bromonitromethanes,iodotrihalomethanes, iodo-acids and brominated forms ofMX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone)(Richardson, 2003) as well as nitrosodimethyl-amine (NDMA).

Potentialsourcewater

organiccontaminan

ts

Pest

icides

Orga

noc

hlorine

pestic

ides

Org

anop

ho-

sp

horus

pes

tic

ides

Am

ides

Pyre

thro

ids

Herbicides

Urac

ils,etc

Hydrocarbons

Po

lycyc

lic

aroma

tic

hy

drocarbons

Alkanes

Alkenes

Longchain

alkylbenzenes

C10-C13

chloroalkanes

(shortchain

paraffins

Perandpoly-

fluoroorganics

Perfluoroacids

(PFAs)

Perfluoroalkyl

carboxylates

(PFACs)

Perfluoro-

octane

sulfonates

(PFOSs

)

Perfluorooctane

sulfonamides

(PFOSAs)

Perf

luoro

hexan

esu

lfona

tes

(PFHx

S)

Perf

luoroa

lky

l-

su

lfona

tes

(PFASs

)

Polyhalogenated

aromatic

hydrocarbons

75congeners

ofFurans

(PCDFs

)

135congenersof

Dioxins(PCDDs

)

Po

lyc

hlorina

ted

bipheny

ls

(PCBS)(209

congeners

)

Polybrominate

dbiphenyls-

PBBs

Polybrominated

biphenylethers

(PBDEs)

Pharmaceuticals

andpersonalcare

products

Na

tura

lan

d

syn

the

tic

stero

ids

&

hormones

Ve

terinary

&

human

an

tibiotics

Prescrip

tionan

dnon-

prescrip

tion

drugs

Lipid

regu

lators

Persona

lcare

pro

duc

tslike

fragrances,

-

Bloc

kers,

PCPs,

like

sunscreenagen

ts&

insec

trepellents

Be

nzotriazoles

Benzo

triazo

le

(BT)

Toy

ltriazo

le

(TT)

Surfactants

Alky

lpheno

ls

Alkylphenol

ethoxylates

&poly-

ethoxylates

Linear

alkylbenzene

sulphonates

(LASs)

Alpha-o

lefin

su

lfona

tes

(AOS)

Alky

l

su

lfona

tes

(AS)

Sulfophenyl

carboxylates

(SCs)

Cyanotoxins

Microcys

tins

Cy

lin

dro-

spermops

in

Sax

itox

ins

No

du

larins

Ana

tox

ins

P

lasticisers

Phtha

lates

Adipates

Phosp

ha

te

es

ters

Additivessuc

h

as

Bisp

heno

lA

Engineered

carbon-based

nano-

particles

Fu

llerenes-

(C60)

Figure 3

Potential source-water organic contaminants found in the literature

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Organic contaminants in distribution systems

The distribution system is also a potential source of organiccontamination of drinking water. Organic contaminants canenter supplies in several ways, that is, through leaching fromplastic materials, application of renovation processes andpermeation of certain plastic pipes, and microbial act ivity inbiolms (Hecq et al., 2006). Some introduction of organicchemicals from distribution systems is inevitable at some level,

part icularly in the early stages, such as with newly-laid pipe orafter a recent renovation (Hecq et al., 2006). Excessive leach-ing of organic substances from pipe mater ials, linings, joiningand sealing materials, coatings and cement mortar pipe haveoccasionally been noted in the literature (Hecq et al., 2006).High density polyethylene pipes (HDPE), cross-bonded poly-ethylene pipes (PEX) and polyvinylchloride (PVC) pipes fordrinking water have been tested for leaching of contaminants(Skjevrak et al., 2003). A range of esters, aldehydes, ketones,aromatic hydrocarbons and terpenoids were identied asmigration products from HDPE pipes (Skjevrak et al., 2003).Phthalamides have also been found to leach from blue MDPE,and this proved to be due to its presence as an impurity relatedto the blue pigment, copper phthalocyanine (Skjevrak et al.,2003). Organotins can leach into drinking water from certaintypes of polyvinyl chloride (PVC) pipes and PAHs, particularlyuoranthene, can leach from the older types of pipes whichwere lined with coal tar pitch (Skjevrak et al., 2003).

Permeation of polyethylene (PE) pipes by organic chemi-cals has been observed (Skjevrak et al., 2003). Leaching oforganic compounds into water from reservoir/tank linings(Skjevrak et al., 2003) and the release of VOCs and SVOCsfrom natural biolms in distribution networks has also beenidentied (Skjevrak et al., 2005). It has also been establishedthat disinfection continues along the distribution networkand new organic contaminants can be formed (Sadiq andRodriguez, 2004). The residence time of water is one important

parameter in explaining the fate of chlorinated disinfectionby-products (CDBPs) (Sadiq and Rodriguez, 2004). Table 2summarises the list of organic contaminants identied in thedrinking water value chain. This list formed part of the pre-liminary l ist of organic contaminants of concern (PLOCC)

after applying the Persistence, Bioaccumulation and

Toxicity (PBT) criteria (Step III, Fig. 2, Table 3).

Once the organic contaminants of possible concern wereidentied, further screening was done using information fromavailable databases. From these sources, values for the physicalproperties and cut-off values characterising the Persistence,Bioaccumulation and Toxicity attributes were obtained.Based on the cut-off values, it was decided whether to excludethe organic contaminant or to add it to the preliminary list of

organic contaminants of concern (PLOCC) (Fig. 2). Values foreach of the contaminants obtained from the above step wereobtained from the literature, and using a yes or no decision-making process a contaminant was characterised as persistentor not persistent, accumulative or not accumulative andtoxic or not toxic. The same was done for other parameters.

Since not all of the organic contaminants had readily avail-able data on the human exposure effects, fate and behaviourin the human body, measurement in environmental samples,removal methods from source water, drinking water qualityguidelines or standards to enable regulation, it was necessary todevelop water quality monographs at this stage (Ncube, 2009;Ncube et al., 2011). Water quality monographs were developedas an additional tool for screening the organic contaminants on

the PLOCPC and those identied through the literature review.Completed water quality monographs were characterised byunique numbers. It was observed that the PLOCPC containedsome organic contaminants which lacked a lot of information,especially on the PBT criteria, removal from water dur ingtreatment, fate and behaviour in the environment and drink-ing water regulation criteria among others. The organic con-taminants which were identied for water quality monographdevelopment were automatically placed on the list of organic

contaminants of concern (Table 2). The organic contaminantslisted in Table 2 were tested for occurrence in the drinking

water value chain in Step IV of the protocol (Fig. 2).

Testing for organic contaminants in a prototype

drinking water value chain occurrence criterion

The occurrence criterion which was qualitatively appliedin Step III by conducting a literature review was quantiedduring this step by testing for the occurrence of organic con-taminants in the dr inking water value chain. The 226 organiccontaminants on the preliminary list of organic contaminantsof concern (Table 2) obtained from Step III were assessed foroccurrence in the Rand Water drinking water value chain.This was achieved by comprehensive laboratory analyses oforganic contaminants in biota (sh tissue), sediments and watersamples. The assessment was conducted twice a year dur ingthe low-ow (dry season) and high-ow (wet season) periods.The aim of this was to determine which organic contaminantsor groups of organic contaminants occur in the drinking watervalue chain (Fig. 2) and in which environmental matrix. Thiswas followed by a decision on whether the organic contaminantshould be listed on the nal list of organic contaminants ofconcern (FLOCC), which was the outcome of this step.

Study sites

Data for assessing the occurrence of organic contaminants inthe Rand Water drinking water value chain (from source to tap)were collected from the following sites: SITE 1: Vaal Dam 1 Vaal Dam, main Rand Water

source water abstraction SITE 2: M-Canal-Raw water canalsource water enter-

ing Zuikerbosch Drinking Water Production Plant SITE 3: D-DB8 Potable water from Zuikerbosch

Drinking Water Production Plant,point located 5 km afterchlorination

SITE 4: D-MAP_S1 Mapleton Booster Station afterchloramination

SITE 5: S1-Tap_Vosloo Tap water at VosloorusTownship along the S1 line from Mapleton.

Field sampling

Sample collection was conducted during the wet season (high-ow period) in November/December 2007 and during the dryseason (low-ow period) in April/May 2007. Sediment, waterand biota (sh) were sampled from the source water environ-ment (Vaal Dam: Site 1, C-VD1)

Fish samples

One sh species was collected from the Vaal Dam;Labeoumbratus (moggel). This is a detritivorous bottom feeder, onsoft mud and detrital sh. Fish were collected by means of gillnets (40 mm to 150 mm stretch mesh size). Only females were

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Table 2

The preliminary list of organic contaminants of concern (PLOCC) based on the occurrence criterion

(evidence from the literature)

Naturally-occurring

organic contaminants

(18)

Industr ial chemicals (63) PPCPs (46) Pesticides (42) Synthetic organic

polymers and residues

(16)

VOCs and SVOCs (66)

Humic acids

uvic acids

organometallics such as

methyltin

dimethyl tinMeHg

cyanotoxins such as anatoxin-a,

homoanatoxin-a, anatoxin-a(S)

saxitoxins

cylindrospermopsin

nodularin

microcystins and

lipo-polysaccharides

geosmin (trans-1,10-dimethyl-

trans-9-decalol)

2-isobutylmethoxy-pyrazine

(2-IBMP)

2-isopropymethoxy-pyrazine

(2-IPMP)

-cyclocitral

2-methylisorboneol (2-MIB)

16 PAHs

PCBs

PCDDs/PCDFs

brominated diphenyl ethers

deca-BDE, octa-BDE and penta-BDEpolybrominated biphenyls

bis-(2-ethylhexyl) adipate (DEHA)

di-(2-ethylhexyl) phthalate (DEHP)

2-chloroethanol phosphate

tri-n-butylphosphate (TBP)

dimethylphthalate (DMP)

diethylphthalate (DEP)

butylbenzylpthalate (BBP)

di-n-butylphthalate (DBP)

bis(2-ethylhexyl)phthalate (DEHP)

di-n-octylphthalate (DOP)

bisphenol A

tributyltin (TBT)

MBT

DBT

DMT

2-chlorophenol

3-chlorophenol

4-chlorophenol

2,3-dichlorophenol

2,4-dichlorophenol

2,5-dichlorophenol

2,6-dichlorophenol

3,4-dichlorophenol

3,5-dichlorophenol

2,3,4-trichlorophenol






2,3,4,5-tetrachlorophenol

2,3,4,6-tetrachlorophenol2,3,5,6-tetrachlorophenol

PCP

linear alkylbenzene sulphonates (LAS)

alpha-olefn sulphonates (AOS)

alkyl sulphates (AS)

alkylphenol polyethoxylates

butylphenol (BP) nonylphenol (NP)

octylphenol (OP)

nonylphenol ethoxylates (NPEOS)

octylphenol ethoxylates (OPEOS)

octamethylcyclotetrasiloxane-D4

decamethylpentasiloxane-D5

peruorohexane sulphonate (PFHXS)

peruorooctane sulphonate (PFOS)

peruorooctane sulphonamide (PFOSA)

peruorooctanoic acid (PFOA)

peruorononanoic acid (PFNA)

peruorodecanoic acid (PFDA)

peruoroundecanoic acid (PFUNDA)

peruorododecanoic acid (PFDODA)

benzotriazole (BT)

tolyltriazole (TT)

fullerenes (C60

)

Heptachlor epoxide

endosulphan II

endrin aldehyde

endosulphan sulphate

endrin ketoneDDT and metabolites

hexachlorocyclohexane (HCH)

atrazine and metabolites

simazine and metabolites

propazine and metabolites

dichlorvos

malathion

glyphosate

omethoate

thionazin

atraton

terbutylazine (TBA)

metribuzin

dieldrin

endrin

methoxychlor

mirex

o,o,o-triethylphosphorothioate

methamidophos

HCB

heptachlor

aldrin

-chlordane

endosulphan

sulphotepp

phorate

dimethoate

disulfoton

parathion-methyl

parathion

isocarbophos

isofenphos-methyl

chlorpyrifosdieldrin

azinphos-methyl

trichlorphos

famphur

endrin

Heptachlor epoxide

endosulphan II

endrin aldehyde

endosulphan sulphate

endrin ketoneDDT and metabolites

hexachlorocyclohexane (HCH)

atrazine and metabolites

simazine and metabolites

propazine and metabolites

dichlorvos

malathion

glyphosate

omethoate

thionazin

atraton

terbutylazine (TBA)

metribuzin

dieldrin

endrin

methoxychlor

mirex

o,o,o-triethylphosphorothioate

methamidophos

HCB

heptachlor

aldrin

-chlordane

endosulphan

sulphotepp

phorate

dimethoate

disulfoton

parathion-methyl

parathion

isocarbophos

isofenphos-methyl

chlorpyrifosdieldrin

azinphos-methyl

trichlorphos

famphur

endrin

Polydiallyl

dimethyl ammonium chloride

(POLYDADMAC)

epichlorohydrin-dimethylamine

(epi-DMA)dimethylamine

allylchloride

diallylether

1,3-dichloro-2-propanol

2,3-dichloro-1-propanol

1,3-bis(dimethylamino)-2-propanol

2-hydroxy-3-dimethylamino

propylchloride

3-chloro-1,2-propanediol

epichlorohydrin

glycidol

5-hexanal

anionic polyacrylamide (PA)

cationic polydimethyl diallyl

ammonium chloride

non-ionic polyacrylamide

2-methylpropanal

2-butanone

chloroform

3-methylbutanal

3-butene nitriledichlorobromomethane

aliphatic amine

isobutylnitrile

1,1`-oxy-bis-(4-chloro-butane)

1,2-dibromobutane styrene

bromoform

1-octanol benzaldehyde

butyldinitrile

benzylnitrile

2-chloro-ethylbenzene

benzylacetonitrile

4-chloro-benzylchloride

1,2-dichloro-ethylbenzene

1-bromo-2,3-dimethyllindane

3-methylbutanal

hexachloroethane

pentanal

4-methyl-2-pentanone

dimethyldisulphide

1-octene

n-octane

1-nonene

4-methylpentanol

2-heptanone

heptanal

2-ethyl-hexanal

1-octene-3-one

3-octanone

6-methyl-5-hepten-2-one

dictyopterene

p-menthon

camphor

menthol2-decenal

5-chloro-1-methyl-imidazole

2-nonanone

chloromethylbenzenemethanol

ectocarpene

1-nonanol

hexachlorocyclopentadiene

2,4-decadienal dodecanal

1,8-cineol (eucalptol)

geosmin

2,6 di-tert-butyl-benzaquinone

tetradecanal

hexadecanal

heptadecene

-ionone

isobutyrate derivatives

trimethylamine

isobutylamine

isopentylamine

dictyopterene a

5-undecen-4-one

5-ethyl-6-methyl-3-hepten-2-one

2,4-di-terbutylphenol

2,4-heptadienal

used for the study due to cost and the fact that gonads (eggs) offemales are known to be suitable tissue for the accumulation oforganics due to their fatty nature.

After capture the sh were transferred to a holding tanklled continuously with water from Site 1. Before dissecting the

sh, the sh were rinsed in water from the body surface. Thesh were then killed by a hard blow on the head. Dissectionwas done on polythene dissection boards using high qualitystainless steel dissection tools. Muscle tissue (skinless), gonads,liver and fat tissue were separated and packaged separately

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according to composite sample requirements. Three compositesamples of each sh tissue were prepared to allow for replicateanalysis. Composite samples were packaged individually inextra heavy aluminium foil, placed in a waterproof plastic bagand, depending on the t ransportation time, kept on wet ice orfrozen on dry ice as per the recommendations of Du Preez etal. (2003). On arrival at the laboratory, the samples were keptfrozen in a freezer until analysis commenced.

Water samples

Samples were collected in triplicate from the 5 locationsdescribed above. The sample bottles were selected dependingon the type of analysis. For example, for pesticide residue anal-ysis, 2.5 amber bottles were used. Water samples for volatileorganic compounds (VOCs), semi-volatile organic compounds(SVOCs) and bisphenol A were collected in 1 glass bottleswith Teon-lined caps. The samples were delivered to therespective laboratories and kept cool at 4C until analysed.

Sediment samples

Surface sediment from the Vaal Dam was collected using theEdman grab methodology. The sediment was collected in 125m wide mouth glass jars with a Teon-lined seal. The sampleswere collected in triplicate and delivered to the respective labo-ratories. Samples were kept cool at 4C until analysed.

Laboratory procedures

The following procedures were used for the assessment oforganic contaminants in sh, sediment and water from theabove sample points. Two approaches were used, namely targetanalysis and multi-residue analysis. For maximum benet,the organic contaminants on the PLOCC were arranged intofunctional groups. This made it possible for most of them tobe screened using the multi-residue analysis approach. In themulti-residue approach, a single extraction method was usedto determine the most commonly encountered pesticides, suchas organochlorine pesticides (OCPs), organophosphorus pesti-cides (OPs), polychlorinated biphenyls (PCBs) and pyrethroid

groups of pesticides, using gas chromatography with an elec-tron capture detector (GC-ECD) or ame photometry detector(GC-FPD), depending on the properties of the compounds. Ifpesticides were detected, the presence of the particular com-pound was conrmed using GC-MS. It is important to notethat not all pesticides would be detected using the multi-residueapproach due to the nature and physical properties of certaincompounds. These could only be detected and quantied usingthe target analysis approach.

In the target analysis approach, a method unique to a spe-cic compound or group of compounds was used. For example,semi-volatile organics in both water and sediment were deter-mined using GC-MS Method AM 186 based on US EPA 8270(USEPA, 2007). Benzene, toluene, ethylbenzene and xyleneisomers, commonly called the BTEX group, were determinedin water samples using the purge-and-trap GC-MS Method GC050, based on US EPA 8260 (USEPA, 1996a). The method isSANAS-accredited for target compound analysis. This analysiswas performed by the CSIR Organic Analysis Laboratory.

Assessment of organic contaminants in sh tissue

On analysis, the samples were passed through a meat mincer.Single determinations on representative portions of the well-mixed samples were carried out using SABS in-house MethodNo. 021/2001 Multi-residue method for the determinat ion of

organochlorine and synthetic pyrethroid pesticide residuesin animal tissue (SABS, 2001). This method was used todetermine the concentration levels of organic contaminants.Recovery determinations were carried out by adding knownamounts of the relevant pesticides to portions of a laboratorycontrol sample and analysing these concurrently with the actualsamples. Organochlorine pesticides, organophosphorus pes-ticides, synthetic pyrethroids and PCB congeners were deter-mined using this method for each sh tissue. Triplicate analysiswas done for each composite sample.

Assessment of organic contaminants in sediment

and water samples

Organochlorine pesticides, organophosphorus pesticides,

Table 3An example of the characterisation of the preliminary list of organic contaminants of concern (PLOCC)

as per screening criteria; Step III of the protocol

Monog

raphnumber

Parameter Human health concern Remarks

Persistent

Accum

ulative

Toxic

Carcinogen

Mutagen

Endocrinedisruptor

Terato

genic

Found

inthedrinking

Watervaluechain

Develo

pwaterquality

monog

raph?

A. INDUSTRIAL CHEMICALS

A1 Benzene Y Y Y Y Y - Y Y Y Also causes taste and odour problems- Chlorobenzene N N Y Y N N N Y N Liver or kidney problems- 1,2-dichlorobenzene N N Y Y Y N Y Y N Liver, kidney or circulatory system problems- 1,2,4-trichlorobenzene N N Y - - - - Y N Changes in adrenal glands- 1,4-dichlorobenzene N N Y - - - - Y N Yellow atrophy and cirrhosis of the liver - Pentachlorobenzene N N Y - - - - Y N Liver and kidney toxicity- Trichlorobenzenes (total) N N Y - - - - Y N See individual CBs- Polynuclear aromatic

hydrocarbonsY Y Y Y - Y - Y N Exert toxic effects through the aryl hydrogen

receptor mediated mechanism

A2 Benzo [a] pyrene Y Y Y Y Y Y Y Y Y Most toxic polynuclear aromatic hydrocarbon

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synthetic pyrethroids, PCB congeners, triazines, chloraceta-mides were analysed using the method as described in theOfcial Methods of Analysis of AOAC International: 16 thEdition, Volume 1 (AOAC International, 1995). Phenoxyaceticacids, 2,4-D and MCPA were analysed using SABS in-houseMethod No. 018/2000 Determination of 2,4-D residues invarious citrus and relevant matrices (SABS, 2000). To analysefor dichlorprop, Method CFP1 1991 for determining residuesof dichlorprop in citrus fruits was used. The EPA Method 625

Base/Neutrals and Acids (USEPA, 1984) were used for extrac-tion in both cases. Carbamate pesticides (aldicarb, aldicarbsulphone, aldicarb sulphoxide, carbaryl, carbofuran, carbosu-fan and propoxur) were analysed using Method No. AM127 andOfcial Methods of Analysis of AOAC International were usedfor extraction.

For the determination of selected volatile compounds onthe PLOCC in sediment samples, such as benzene, toluene,ethylbenzene, m,p-xylene and o-xylene (BTEX group) an in-house Headspace GC-MS Method AM191, based on USEPAmethods 5021 (USEPA, 1996b) and 8260 (USEPA, 1996a) wasused. This is a target compound analysis. Bisphenol A wasdetermined using a CSIR in-house GC-MS method. Semi-volatile organic compounds were determined using an in-houseGC-MS method, AM 186 (based on USEPA method 8270)(USEPA, 2007).

Statistical procedures and data processing

The objective of data analysis was to nd out whether or notthere was a signicant difference among the 5 sites, amongthe 3 matrices per site for the rst 2 sample sites, among the11 groups per matrix, and to assess the effect of samples forsignicance. This is a typical generalised linear modellingprocedure in stat istics. The statistical model used was the uni-variate repeated measures analysis of variance (ANOVA). Themodel was univariate as there was only one outcome variableof interest (the level of concentration of each organic compound

obtained from each sample). Data entry and analysis was doneusing the statistical package STATA Version 10. Generalisedlinear models were used for extensive data analysis. Standarddiagnostic procedures for generalised linear models were usedto assess the adequacy of the tted model.

The validation of the FLOCC by drinking water

industry experts

The main aim of this step was to conrm the need to prioritisethe organic contaminant(s) or group of organic contaminantsfor monitoring in the drinking water value chain and to conrmthe nal list of organic contaminants of concern (FLOCC). Thepreliminary list of organic contaminants of concern (PLOCC;

Table 2) obtained from Step III was also presented to thegroup of experts from the drinking water industry and relevantstakeholders for validation. The workshop was informed ofthe results of the assessment of PLOCC organic contaminantsin the drinking water value chain. At this workshop it wasagreed that most of the organic contaminants on the PLOCCwere already in the WHO drinking water quality guidelinedocument (WHO, 2004), which receives extensive internationalrolling revision. Factors such as relevance to the South Africandrinking water industry, potential for being detected in any ofthe critical control points along the drinking water value chain,evidence of adverse human health effects, previous regulation,such as the Stockholm Convention dirty dozen and beingregistered for use in drinking water treatment, were considered

during the exercise. Those organic contaminants that weredetected in any matr ix of interest during the assessment foroccurrence in the drinking water value chain were moveddirectly onto the FLOCC (Table 4).

The following aspects were also considered in identifyingcompounds for the FLOCC. It was agreed that: Benzo[a] pyrene is the most toxic of all the 16 recognised

PAHs, hence it will not be necessary to analyse for all 16but to use BaP as an indicator for assessing contamination

by PAHs. Benzene is a known human carcinogen. It is already being

analysed for in the BTEX group for protection againstorganoleptic properties such as taste and odour and tosafeguard against consumer complaints. If benzene isappropriately controlled in the drinking water value chain,chlorinated benzenes will be minimised, especially thoseforming after chlorination.

Glycol ethers have been associated with taste and odours insurface waters. It was decided to adopt the group as beingof concern.

Plasticisers such as bisphenol A, di-n-butylphthalate, anddi-(2-ethylhexyl)phthalate, and detergent metabolitesoctylphenol and nonylphenol, are known for their oestro-gen-mimicking effects as evidenced from previous localresearch.

The dirty dozen list on the PLOCC was adopted as the listof organic contaminants of concern. Hence it was automati-cally transferred on the FLOCC.

It was decided to move all organochlorine pesticides withenough information on occurrence and potential adversehealth effects, as shown by the literature and the assess-ment exercise, onto the FLOCC.

Some parent organic contaminants such as hexachlorocy-clohexane (HCH) have no signicance to drinking waterbut have isomers, such as -HCH, -HCH, -HCH, whichhave been found to cause endocrine disruption effects and

liver tumours and are persistent in the environment. Thesame applies to triazine herbicides such as atrazine andsimazine which degrade into more stable metabolites ofgreater human health concern.

Benzene and its chlorinated products were moved onto theFLOCC due to taste and odour concerns.

Synthetic polymer residues, especially those that are knownbe in use in some water treatment plants, were also movedonto the FLOCC.

Disinfection by-products which have been positivelyidentied during the assessment in the drinking watervalue chain and those that are currently regulated were alsomoved onto the FLOCC.

Polychlorinated biphenyls are currently being regulated in

South Africa under the Africa Stockpiles Project. It wasagreed that the group consists of a number of congeners.Only those contaminants that have been detected andwhose standards are available were added onto the FLOCC.Another proposal was the analysis of PCB-153 as an indi-cator of the group since standards for this congener areavailable.

Pharmaceuticals and personal care products which weredetected in aquatic environments were moved onto theFLOCC due to their perceived risks.

From the preceding step, it was evident that some of theorganic contaminants on the PLOCC were excluded from theprocess. One hundred and twenty (120) organic contaminants,

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including some metabolites where relevant, were identied forthe FLOCC (Table 4).

Establishment of technical capability for the removal

of organic contaminants through conventional

water treatment, and recommendations for the

implementation of the FLOCC

The assumptions inuencing this step were that rural com-

munity-based water utilities, and some urban ones, especiallyin developing countries, still have poor infrastructure thatdoes not meet the current challenges for organic contaminantremoval, and some organic contaminants can escape the treat-ment process and be a potential risk to the consumer. Based onthese assumptions it was recommended that rural community-based utilities and those that do not have the capacity to removeselected groups of organic contaminants should test for organiccontaminants in their drinking water value chains. In this case,those laboratories that are accredited for organic analysis orwith the capability for analysis, such as in universities and sim-ilar research organisations, can be used by the water utility toanalyse its water samples. The organic contaminants positivelyidentied in such programmes will be added to the preliminarypriority list of organic contaminants (PPLOC). In South Africa,such evidence could be gathered from national published docu-ments such as Water Research Commission (WRC) projectreports and art icles published in Water SA.

Prioritisation of the organic contaminants on the nal

list of organic contaminants (FLOCC)

The 120 organic contaminants on the FLOCC list were priori-tised using the criter ia presented in Step VI of the protocol. It

was agreed that the highest-priority chemicals are those that havebeen shown to cause human health effects as a consequence ofexposure through drinking water. It was decided that the high-priority chemical list can be modied if those chemicals arefound not to be present, but a chemical not found in an initialinvestigation should not be forgotten. As a result, the prioritisa-tion criteria were applied to the FLOCC but observations madein other steps were used to take a nal decision on whether toeliminate an organic contaminant from the preliminary priority

list of organic contaminants, or to add it to the list.

Occurrence criterion

Evidence for occurrence of the organic contaminant was col-lected in 4 tiers in preceding steps, i.e., from the literature,in the water quality monograph development process, usingexpert knowledge and judgement, and testing for the occur-rence of organic contaminants in the dr inking water valuechain. This was followed by a decision on whether the organiccontaminant was positively identied or not in the drinkingwater value chain. The responses are indicated as shown inTable 5 under the column Found in the dr inking water valuechain?. The response is indicated qualitatively in the form ofY for yes or N for no.

Adverse human health criterion

The information gathered from the literature review and waterquality monographs was used at this stage as it would alreadybe available in Table 5. This information and the informationobtained from the preceding section is combined to assist inpriorit ising the organic contaminants in 4 groups. At this stage,the prioritisation approach identies:

Table 4The nal list of organic contaminants of concern (FLOCC)

Industrial chemicals (31) Pesticides (32) Disinfection by-products (DBPs)(18)

Polymer residues (13) Cyanotoxins (10) PPCPs (26)

Benzene

Chlorobenzene

1,2-Dichlorobenzene

1,2,4-Trichlorobenzene

1,4-Dichlorobenzene

Pentachlorobenzene

2-Chlorophenol

2,4-Dichlorophenol

2,4,6-Dichlorophenol

Pentachlorophenol

Di-2-(ethylhexyl)phthalate

Di-n-butylphthalate

Di-2-ethylhexyladipate (DEHA)

2,3,7,8-Tetrachlorodiphenyldioxin

Nitrilotriacetic acid (NTA)

Benzo[a]pyrene

Bisphenol A

Ethylbenzene

Ethylene glycol monethylether

Ethylene glycol methyl ether acetate

Ethylene glycol monobutyl ether

Acetate

p-Octylphenol

p-Nonylphenol

Polychlorinated biphenyls (Aroclor 1016,

Aroclor 1254, A roclor 1260)

Toluene

Xylene isomers

Dibutyltin

Dimethyltin

Tributyltin

2,4-Dichlorophenoxyacetic

acid [2,4-D]

Fenoprop

MCPA

Aldrin*

Atrazine and metabolites*

Dieldrin*

Chlorpyrifos

Cyhexatin

DDT*

DDD

DDE*

Diquat

Endosulphan

Endosulphan sulphate

-Endosulphan

Endrin

Heptachlor*

Heptachlor epoxide

Lindane

Methoxychlor

Paraquat

Simazine*

Terbutylazine*

Acetochlor

Metolachlor*

Aldicarb*

Deltamethrin*

Vinclozolin

Cyanazine

Hexachlorobenzene (HCB)

HCH isomers

Cypermethrin

Chloroform*

Bromodichloromethane*

Dibromochloromethane*

Formaldehyde

Trichloroacetaldehyde

Monochloroacetic acid

Trichloroacetic acid

Dichloroacetic acid

Bromoacetic acid

Dibromoacetic acid

Bromochloroacetic acid

Dichloroacetonitrile

Trichloroacetonitrile

Bromoacetonitrile

Chloroacetonitrile

Bromoacetonitrile

Dibromoacetonitrile

Nitrosodimethylamine

THMs*

Acrylami de

Epichlorohydrin

Diallyldimethylammonium chloride

Dimethylamine

Allyl chlor ide

Diallyl chloride

5-Hexanal glycidol

1,3-Dichloro-2-propanol


3-Chloro-1,2-propanediol

2-Hydroxy-3-dimethylaminopropyl chloride

1,3-Bis (dimethylamino)-2-propanol

Geosmin*;

2-MIB*

Anatoxin-a

Homoanatoxin-a

Anatoxin-a(S)

Microcystins

Saxtoxins

Cylindrospermopsin

Nodularin

-Methylaminoalanine

Triclosan

Trimethropin

Erythromycine

Lincomycin

Sulphamethaxole

Amoxycillin

Ibuprofen

Diclofenac

Fenoprofen

Naproxen

Acetaminophe n

Acetylsali cylic acid

Fluoxetine

Paracetamol

Clofbric acid

Bezafbrate

Fenofbric acid

Carbamazepine

Cotinine

-Coprostanol

Primidone

Gemifbrozil

17-Estradiol

Estriol

Estrone

17-Ethinylestradiol

*Detected in the Rand Water drinking water value chain

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Contaminants that are demonstrated to have relatively hightoxicity with high potential to occur in the drinking watervalue chain (Table 5)

Contaminants that are demonstrated to have relatively hightoxicity with minimal actual or potential occurrence in thedrinking water value chain (Table 5)

Contaminants that are demonstrated to have high potentialto occur in the drinking water value chain with relativelymoderate toxicity (Table 5)

Contaminants that are demonstrated to have minimalpotential to occur in the drinking water value chain withrelatively moderate toxicity (Table 5)

The approach considers and uses as many of the available typesof health effects and occurrence data identied in the datasource evaluation as practical (Table 5).

Other criteria

The above list was further prioritised using the drinking waterindustry perspective and requirements. It was advisable thatlocal conditions should dene this process. The criteria coveredaspects such as: The availability of standards/guidelines for regulation Potential to cause water quality problems Potential to stimulate customer perception of risk

Removal efciency and availability of expertise and capac-ity for analysis

Based on these criteria, a semi-quantitative approach wasused and 3 priority lists of organic contaminants were identi-ed (Table 5). The organic contaminants were prioritised intoshort-term (S), medium-term (M) and long-term (L) priority foranalysis in the drinking water value chain. Those organic con-taminants placed on the short-term priority list were adoptedfor immediate routine monitoring in the drinking water valuechain.

Short-term(S) Organics falling within this category arelisted in Table 5 and are selected based on the followingcharacteristics: the wide range of potential human healthconcerns via the dr inking water ingestion route; the sub-stance is known to cause water quality problems in thedrinking water value chain such as the cause of offensivetastes and odours; evidence that the occurrence of a sub-stance or group increases customers perception of risk;enough resources in place to support ease of monitoring;poor removal efciency using conventional water treat-ment methods; availability of drinking water standards/guidelines to enable regulation and proof of occurrence inthe drinking water value chain, especially those contami-nants formed during drinking water treatment, distribution,

Table 5The Preliminary Priority List of Organic Contaminants (PPLOC) for monitoring

in the drinking water value chain (example details in Ncube, 2009)

Monogra

phNumber

Parameter Units Standard/Guideline Human health concern Remarks

Currentlyanalyzedfor?

Persistent

Accumulative

Toxic

Carcinog

en

Mutagen

Endocrin

edisruptor

Teratoge

nic

Foundin

thedrinking

Waterva

luechain

Priorityforanalysis

A. INDUSTRIAL CHEMICALS

A1 Benzene g/ 10(WHO), 5(USEPA),10(NZ), 1(AU)

Y Y Y Y Y Y - Y Y S Taste and odour problems

A2Benz [a] pyrene g/ 0.2(US), 0.7(WHO), 0.7 (NZ),

0.01(EU), 0.01(AU)Y Y Y Y Y Y Y Y Y S Most toxic polynuclear aro-

matic hydrocarbonB1 2,4 Dichlorophenoxy-

acetic acidg/ 70(USEPA), 30(WHO),

40(NZ)Y N N Y Y N Y N Y S Currently regulated herbicide

B2 Aldrin g/ 0.03(WHO), 0.04(NZ),0.03(USEPA), 0.03(EU),

0.3(AU),0.7(Can)

Y Y N Y Y Y Su N Y S Immediately convertedto dieldrin in the aqueous

environment- Pendimethalin g/ 20(WHO), 20 (NZ), 300(AU) N Y Y Y - N - N N L Liver toxicity

- Linuron(herbicide) g/ - N N - Y Y N Y N - L Testicular hyperplasia

E5 Allyl chloride g/ - N N N Y Y Y - - N/A M No criteria for regulation

E6 Diallyl ether g/ - N N N Y Y - - - N/A M VOC, no drinking watercriteria

- Pentachlorobenzene g/ - ? N N Y - - - - N/A S Liver and kidney toxicity

- Trichlorobenzenes(Total)

g/ 30(AU) Y N N Y - - - - N/A S See individual CBs

- Polynuclear aromatichydrocarbons

g/ 0.10(EU) Y Y Y Y Y - Y - N/A S Toxic effects, aryl hydrogenreceptor mechanism

Notes: Y-Yes, N-No, Su-Suspected, S-Analysis in the short term (1-2 years), M-Analysis in the medium term (3-5years), L-Analysis in the long

term (5-10 years), N/A-Not assessed

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storage and use. At least four or more aspects must be satis-

ed of which the potential to cause adverse health effectsand water quality problems must be part of them. Medium-term(M) substances falling within this category

are listed in Table 5. Organic constituents in this categoryare selected based on the following characteristics: Thewide range of potential human health concerns via thedrinking water ingestion route; ability to cause waterquality problems in the drinking water value chain such asthe cause of offensive tastes and odours; evidence that theoccurrence of a substance or group increases customersperception of risk; no resources in place to support easeof monitoring; moderate removal efciency using conven-tional water treatment methods; non-availability of dr ink-ing water standards/guidelines to enable regulation; proof

of occurrence in the drinking water value chain especiallythose contaminants formed during drinking water treat-ment, distribution, storage and use.

Long-term(L) substances falling within this category arelisted in Table 6. Organic constituents in this category areselected based on the following characteristics: insufcientinformation on human health concerns via the drink-ing water ingestion route; insufcient information on theimpact of the organic contaminant on drinking water qual-ity; no evidence that the occurrence of a substance or groupincreases customers perception of risk; no resources inplace to support ease of monitoring; removed from drink-ing water using conventional water t reatment methods;non-availability of drinking water standards/guidelines

to enable regulation; proof of occurrence in the drinking

water value chain especially those contaminants formedduring drinking water treatment, distribution, storage anduse. On completion of the preceding steps, 3 categories oforganic constituents of importance to the water utility andits customers were established (Table 5). The outcome ofthis step was a preliminary priority list of organic contami-nants (PPLOC) for monitoring in the drinking water valuechain (Table 5). This list was nalised after consulting withthe relevant experts at a workshop.

Validation of the priority list of organic contaminants

by drinking water industry experts and relevant

stakeholders

The preliminary pr iority list of organic contaminants obtainedfrom Step VI (Table 5) was presented to a group of expertsfrom the drinking water industry and relevant stakeholdersfor validation. At this workshop, industry-specic criteria andanalytical challenges were identied as other aspects affectingorganic analysis by water utilities. The preliminary priority listof organic contaminants (PPLOC; Table 5) was assessed andthe priority list of organic contaminants nalised. All con-taminants with priority S for analysis were moved onto thepriority list of organic contaminants (Table 6). Benchmarkingwith other national and international bodies such as the WHO,USEPA, OECD and EU was done at this stage. However,local conditions and relevancy were given more emphasis.The outcome of this step was a list of 100 priority organic

Table 6The priority list of organic contaminants for monitoring in the drinking water value chain

Industrial chemicals (29) Pesticides (37) Disinfection by-products (DBPs)(13)

Polymer res idues (7) Cyanotoxins(9)

PPCPs (5)

Benzene

Chlorobenzene

1,2-Dichlorobenzene

1,2,4-Trichlorobenzene

1,4-Dichlorobenzene

Pentachlorobenzene2-Chlorophenol

2,4-Dichlorophenol

2,4,6-Dichlorophenol

Pentachlorophenol

Di-2-(ethylhexyl)phthalate

Di-n-butylphthalate

Di-2-(ethylhexyladipate (DEHA)

2,3,7,8-Tetrachlorodiphenyldioxin

Nitrilotriacetic acid (NTA)

Benzo[a]pyrene

Bisphenol A

Ethylbenzene

p-Octylphenol

p-Nonylphenol

Polychlorinated biphenyls

(Aroclor 1016; Aroclor 1248;

Aroclor 125 4; Aroclor 126 0)

TolueneXylene isomers

Dibutyltin

Dimethyltin

Tributyltin

2,4-Dichlorophenoxyacetic acid [2,4-D]

2,4,5-TP

Fenoprop

MCPA

Aldrin*

Dieldrin*Atrazine and metabolites*

Chlorpyrifos

Cyhexatin

DDT*

DDD

DDE*

Diquat

Endosulphan

Endosulphan sulphate

-Endosulphan

Endrin

Heptachlor*

Heptachlor epoxide

Lindane

Metolachlor*

Methoxychlor

Paraquat

Simazine*Terbutylazine*

Acetoch lor ethanesulphonic acid

Acetocl or

Acetoch lor oxanilic acid

Metolachlor ethanesulphonic acid

Metolachlor oxanilic acid

Aldica rb*

Deltamethrin*

Vinclozolin

Chlordane cis,trans-isomers

Hexachlorobenzene (HCB)

HCH isomers

Cypermethrin

Chloroform*

Bromodichloromethane*

Dibromochloromethane*

Formaldehyde

Trichloroacetaldehyde

Monochloroacetic acidTrichloroacetic acid

Dichloroacetic acid

Bromoacetic acid

Dibromoacetic acid

Bromochloroacetic acid

Nitrosodimethylamine

THMs*

Acrylam ide

Epichlorohydrin

Diallyldimethylammonium chloride

Dimethylamine


2,3-Dichloro-1-propanol3-Chloro-1,2-propanediol

Geosmin*

2-MIB*

Anatoxin -a

Homoanatoxin-a

Anatoxin -a(S)

Microcystin-LRSaxtoxin

Cylindrospermopsin

Nodularin

17-Estradiol

Estriol

Estrone

17-Ethinylestradiol

Diethylstilbestrol (DES)

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contaminants for monitoring in the drinking water value chain.This includes key metabolites and isomers for organochlorinepesticides such as DDT, chlordane, hexachlorocyclohexane(HCH), acetamide herbicides such as metolachlor and acetoclorand metabolites of S-tr iazine herbicides.

Results and discussion

The implementation of the protocol began with the identica-

tion of potential drinking water organic contaminants pr ior toany attempts to screen or sort them. These covered a range oforganic contaminants that the consumers can be exposed tovia the drinking water ingestion route, dermal contact dur-ing recreational activities including other relevant water usesand the inhalation route. During the validation of the poolof organic contaminants, workshop attendees felt that mostorganic contaminants were already represented in the WHOguidelines for drinking water quality document, (3rd edition)published in 2004. It was therefore agreed that the list willform part of the working document to be used in Step II of theprotocol. The reasons given were the fact that the document isproduced by experts across the world and undergoes a roll-ing revision to update the information. This emphasized therole of expert judgment in decision-making. In this study, theoccurrence criteria, evidence of occurrence in environmen-tal samples collected along the drinking water value chain,and expert judgment were considered adequate for an organiccontaminant to be placed on a priority list of organic contami-nants for monitoring in the drinking water value chain. In theevent that the occurrence criteria, the PBT criteria and infor-mation gathered during the water quality monograph develop-ment were not enough to assist the decision-making process onwhether to place the organic contaminants on the list of organiccontaminants of concern (Table 3), other criteria relevant to thedrinking water industry were used.

The major challenge was the limited information on some

organic contaminants to allow for decision making basedon the occurrence and human health effects criteria. Thiswas true for compounds such as synthetic organic polymerresidues; allyl chloride, diallyl ether, 5-hexanal and glycidol,identied benzotriazoles, some plasticisers such as 2-chloro-ethanol phosphate and tri-n-butylphosphate, some pesticidessuch as 3,4-dichloroaniline, 3,3,4,4-tetrachloroazobenzene,disulfuton, isocarbophos and hexachlorocyclohexane, whichhas been proved to not be as important as its isomers (Zhou etal., 2001; Zhang et al., 2003; Voutsa et al., 2006). Pesticidessuch as MCPB, 2,4-DB, mecoprop, dichlorprop, fenoprop,2,4,5-T were not frequently detected in the drinking watervalue chain. There was also limited information concern-ing the occurrence of atrazine and its metabolites, although

evidence suggests that they are suspected endocrine disrup-tors and some of the metabolites have been found to occurin surface waters which might be used as sources for drink-ing water product ion. It was, however, decided to keep themetabolites on the list. Pharmaceuticals and personal careproducts (PPCPs) have limited information to sat isfy the PBTcriteria. However, most have been found to occur in sourcewater resources. These include compounds such as diclofenac,ibuprofen, amoxicillin, chloramphenicol, sulphamethaxole,lincomycin, trimethoprin and triclosan. These compoundswere kept on the PLOCC due to other concerns such as thefact that they are continuously added to the environmentand as emerging organic contaminants a lot of research iscurrently being conducted to establish their public health

signicance in the aquatic environment. Details are given inNcube (2009).

Metolachlor was detected in all water samples, from theVaal Dam to the tap, while atrazine, simazine and terbutyla-zine were below the detection limits dur ing the wet season.Other contaminants positively identied along the Rand Waterdrinking water value chain include the disinfection by-productschloroform, bromodichloromethane and dibromochlorometh-ane, and cyanotoxin products 2-methylisoborneol and geosmin.

All contaminants which were positively identied occurred atconcentrations lower than the recommended drinking waterquality guideline or standard when compared with the WHOdrinking water guidelines (WHO, 2004), and which there-foredo not constitute a health hazard. The rest of the organiccontaminants were either below the detection limit or gavea not detected (nd) result. Aldicarb and its metabolites weredetected at a level of 0.02g/kg in sediment samples from theVaal Dam. Heptachlor was detected in sh fat tissue, dieldrinin fat tissue and gonads and p,p-DDE in fat and gonads duringthe low-ow season (dry period). During the high-ow season,p,p-DDE was detected in all 4 sh tissues while deltamethrin,a pyrethroid, was detected in muscle tissue. The results weresubjected to statistical analysis as described in preceding sec-tions. The details are given in Ncube (2009).

The assessment of organic contaminants for the occur rencecriterion was performed using both multi-residue analysis andtarget compound analysis. However, most results were eitherbelow the limit of detection (LOD), below the method report-ing limit (MRL) or non-detected (nd). This became a majorchallenge in data interpretation and application of the occur-rence criterion. Measurements below the detection limit raisethe degree of uncertainty as this happens as a result of a num-ber of factors. For example, it cannot be reliably asserted thatthey are statistically different from zero. These is a cause forconcern since most organic contaminants on the preliminarypriority list occurred at levels lower than the detection limit

or were reported as not detected. This constitutes a limita-tion in implementing the occurrence criterion (Step III of theProtocol). However, due to their properties, it will be advis-able to continue monitoring for these organic contaminants,especially in source water. This is due to the fact that organiccontaminants are found in the water column at very low con-centrations. It has also been observed that investigations orassessments of organic contaminants related to chronic lowlevel exposures or related situations often face the difcult taskof dealing with levels of contamination that are hard to detectand/or quantify.

Another limitation for the implementation of the occur-rence criterion is the assurance that the non-detection of aparent compound means its absence in the mat rix of interest,

as it is possible that the compound might have been degradedinto metabolites that are either more or less persistent or toxic.In reality, if the parent compound breaks down quickly intoits metabolites, it will denitely be detected at lower levels inthe matrix of interest or not detected at all. An example is thecase of the S-triazine herbicides which are degradable once inthe soil or aqueous environment. Transformation products oforganic contaminants have the potential to be similarly or evenmore mobile, persistent or toxic than their parent compounds.These should therefore be included in the assessment of waterquality, sediment and biota in order to safeguard human health.

It will therefore be prudent to consider analysing for thedegradation products in water, including the parent compounds.Atrazine has been found to have a half-life of 3090 days in the

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environment. The detection of apparent residues of these her-bicides in the d rinking water value chain is an indication thatthey do persist in the aquatic environment, especially sourcewater, and need to be analysed for. Atrazine was detected inmost samples, except sediment and sh, in both seasons. Thedetection of p,p-DDE in most sh tissue is an indicator thatthe most persistent and bio-accumulative DDT metabolite isp,p-DDE. Dieldrin was also detected in sh gonads. Dieldrinoccurs as a metabolite of the unstable aldrin which is immedi-

ately converted to dieldrin once in the environment.

Conclusions

During the validation exercise, the following was noted: Thegeneric protocol for the selection and prioritisation of organiccontaminants for monitoring in the drinking water value chainhas been successfully implemented in a prototype drinkingwater value chain. The area in which the protocol was tested isone of the biggest water utilities in Africa and the assessmentcovered the whole drinking water value chain from catchmentto tap. A priority list of organic contaminants has been identi-ed for use by Rand Water and other water utilities. Organiccontaminant monitoring is currently in place. Sampling is donetwice a year during the high- and low-ow periods.The occurrence, potential exposure and human health effectscriteria play a major role in selecting and pr ioritising organiccontaminants for monitoring in the drinking water value chain.Industry-specic criteria such as existence of drinking waterquality guidelines or standards, availability of capacity foranalysis, extent of use of certain organic contaminants in localcatchments, relevance of a particular contaminant or group ofcontaminants to the drinking water industry under local condi-tions, ease of monitoring, and removal of contaminant duringwater treatment, also play a signicant role during the prioriti-sation of organic contaminants for monitoring in the drinkingwater value chain.

Tailor-made prioritisation criteria reective of the drinkingwater industry perspective are important, and have proven tobe successful in selecting and pr ioritising organic contaminantsfor monitoring in the drinking water value chain. The organiccontaminants in the current study were successfully prioritisedin 3 classes, short-term priority for analysis, medium-termpriority for analysis and long-term pr iority for analysis. This isa very important guide for water utilities to assist in optimis-ing their resources while not compromising the role of publichealth protection.

Acknowledgement

The authors would like to thank the Rand Water Board for

sampling logistics arrangements and nancial assistance duringthis study.

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