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38 AUGUST 2014 | JOURNAL AWWA • 106:8 | 100TH ANNIVERSARY | SNYDER

A ll life depends on complex chemical interactions because organisms are composed ofand use an innumerable diversity of organic and inorganic chemicals for survival.With more than 200,000 years of experience, humans have become uniquely adeptin modifying the natural environment to improve and extend their lives. Yet withburgeoning population growth and urbanization, humankind faces new challengesin the procurement of resources and disposal of wastes. Perhaps one of the greatharbingers of this challenge has been the widespread occurrence of pharmaceuticalsin drinking water (Benotti et al, 2009). Pharmaceuticals were first reported to occurin waters of the United States in the 1970s (Hignite & Azarnoff, 1977; Garrison etal, 1975), but it was not until the late 1990s that these substances gained tremendousattention as environmental contaminants (Daughton & Ternes, 1999). The increasedattention was primarily due to reports of steroid hormones in wastewater potentially

affecting fish (Snyder et al, 2001; Desbrow et al, 1998) and, to an even greater extent,

This article provides historical and current

perspectives of the methods used and policies

instituted to monitor and address the daunting list

of chemical contaminants in water; progress is

steadily made, but there is more work to be done.

Emerging chemicalcontaminants: Lookingfor greater harmony

SHANE A. SNYDER

2014 © American Water Works Association



SNYDER | 100TH ANNIVERSARY | 106:8 • JOURNAL AWWA | AUGUST 2014 39

reports of pharmaceuticals occurring in

tap water (Benotti et al, 2009). The detec-tion of human pharmaceuticals in tapwater is indeed a stark reminder of theubiquity and density of human existence.It also is a concrete reminder of the poten-tial for contaminants to flow with wateras part of the water cycle, a cycle that isessential for sustaining life. However, isthis example necessarily evidence of abreach in water safety?

As analytical technologies continue toadvance and more chemicals enter com-

merce, we can be reasonably certain thatnew chemicals will be discovered in waterat even lower concentrations. Accordingto Chemical Abstracts Services, more than88 million organic and inorganic chemi-cals have been registered, more than 65million chemical products are availablecommercially, and approximately 15,000new chemicals are added per day (www.cas.org). Our historical and current para-digms for evaluating occurrence, fate, andtoxicity cannot possibly keep pace with

chemical development and commercializa-tion, let alone regulatory evaluation forprotecting drinking water. For instance,consider that perchlorate, for which thereexists a relative wealth of occurrence andtoxicity data (including occupationalexposure and obtained through use as ahuman pharmaceutical), remains withouta maximum contaminant limit goal(MCLG) after more than a decade ofdebate. Using current methods for devel-oping an MCLG, the task of addressing

unregulated contaminants that have arelatively high frequency of occurrence inUS drinking water alone is likely insur-mountable. This author firmly believesthat the existing paradigm for evaluatingthe potential health risks of chemicals indrinking water is far too slow and is vastlyincapable of coping with the rapid discov-ery of new chemical contaminants inwater, particularly when transformation/ disinfection by-products are considered.

As an example, far more human health–

related data are available for pharmaceuti-

cals than for any other class of environmen-

tal contaminant because all prescriptionpharmaceuticals in the United States haveundergone extensive animal testing andclinical (human) testing before approval. Ifwater and health experts cannot come toconsensus on whether trace pharmaceuti-cals in water pose a risk to human health,we can only begin to imagine the moredaunting challenge of addressing thosecontaminants that have never been tested

on humans, such as pesticides and disinfec-tion by-products.

Our current system of testing chemicalson animals at exceedingly high doses andextrapolating to estimate risk levels at thefar lower concentrations occurring indrinking water is antiquated, painfullyslow, and greatly surpassed by developmentof occurrence data. Increasing numbers ofscientific studies demonstrate that somechemicals, singly and as mixtures, can exerttoxicologically relevant effects in animalsat doses far lower than previously expected(Kortenkamp, 2007). Not only is the dose

of a chemical important, but the timing ofan exposure during an animal’s develop-ment can also determine the severity of aparticular effect. Perhaps the most dramaticand troubling example is the previous useof the drug thalidomide for morning sick-ness in pregnant mothers (Melchert & List,2007). Fetal exposure to thalidomide dur-ing the third trimester of development oftenresulted in devastating birth defects, mostnotably deformed limb development.Recent concerns have arisen regarding the

potential for inherited effects from parental

As analytical technologies continue to advance and more chemicals

enter commerce, we can be reasonably certain that new chemicals

will be discovered in water at even lower concentrations.





exposure to chemicals, known as epi-

genetics (Collotta et al, 2013). Anothercritical consideration for drinking waterexposures is the potential of additive orsynergistic effects. Indeed, environmentalexposures do not occur as single chemicals;rather, they occur as complex mixtures thatrapidly change in composition and concen-tration. Some chemical mixtures are knownto exert biological activity in an additivefashion, such as certain types of endocrinedisrupting chemicals (Kortenkamp, 2007).Thus, individual chemical testing in animals

under the current risk assessment paradigmrepresents a scenario that simply does notoccur in nature. Collectively, these examplesshow the complexity and fragility of humantoxicology and the need for more holisticrisk assessment paradigms that considerreal-world exposure scenarios.

As the list of emerging contaminantsexpands and corresponding analyticalmethods for identification and quantifi-cation become more sensitive and selec-tive (Richardson & Ternes, 2014), there

is no question that exposure assessmentwill greatly outpace health assessment.Therefore, the following paths for ad-dressing emerging contaminants in waterare recommended: (1) harmonized toxi-cological and fate characterization ofchemicals before entering commerce, (2)surrogate and indicator monitoring tocharacterize source waters and evaluatetreatment efficacy, (3) discrete chemicaland mixture toxicological screening usingrapid bioassays, and (4) comprehensive

occurrence evaluation using high-resolu-tion mass spectrometry.

THE MAGNITUDE OF THE SITUATION

The United States does not have a coor-dinated program that comprehensivelyaddresses the fate and effects of chemicalsin commerce entering the environment(Novak et al, 2011). Although the UnitedStates has several programs to evaluateand regulate chemicals, the efforts are gen-erally disparate and disjointed with an

apparent lack of harmony among federal

agencies. For instance, better coordination

of maximum residue limits in food in con-sideration of drinking water regulationscould help inform relative source contribu-tions, which often show that drinkingwater is a minor source of chemical expo-sure as compared with diet (Stanford et al,2010). Perhaps the most prudent exampleis the apparent disconnect between theSafe Drinking Water Act and Clean WaterAct, which may become increasinglyimportant as potable water reuse effortscontinue to grow and expand. There have

been numerous coordinated efforts regard-ing nanoparticles and nanotechnologiesthat may serve as an example for coordi-nation of programs for evaluation of otherchemicals, some of which have demon-strated environmental impacts (Kidd et al,2007). Harmonization of federal chemicalscreening and prioritization programscould aid in avoidance of redundancy,result in cost reductions, and lower theamount of animal testing required whileproviding more rapid and meaningful data

for evaluating risks to waters supplies.The Toxic Substances Control Act

(TSCA) provides the US EnvironmentalProtection Agency (USEPA) with theauthority to require reporting, recordkeeping, and testing requirements for newand existing chemicals in commerce.Although TSCA was enacted in 1976, thelegislation has never been amended (Locke& Myers, 2010). The overarching aim ofTSCA is to ensure that chemicals in com-merce do not pose “an unreasonable risk

of injury to health or the environment”and requires the USEPA Administrator toconsider “the environmental, economic,and social impact of any action” (Locke &Myers, 2010). Under Section 4 of TSCA,USEPA has the authority to require that achemical be tested for environmental andhuman health effects; however, USEPAmust first establish a hazard finding orexposure finding before requiring testing(Locke & Myers, 2010). Essentially,USEPA is required to prove a risk exists

before it can require the data that would

I started reading JOURNAL AWWA

in the 1960s and having added a

“few” years now, I can almost see

back to when Abel Wolman was

editor, and AWWA was leading a

knowledge revolution about safe

drinking water. It is inspiring to

read the older papers and see

how water industry leaders

confronted the issues.

The mixture of practical papers

with cutting-edge science

seemed like the right way to put

research into action. I even liked

the ads. JOURNAL AWWA and AWWA

have made great contributions to

my professional growth, and I

appreciate the good people who

made it happen along the way.

—Neil Grigg, Professor,

Department of Civil and

Environmental Engineering,

Colorado State University





help prove there actually is a risk. This

circular argument is challenging to over-come and often results in enforceable con-sent agreements or voluntary testingagreements between industry and USEPA.More than 84,000 substances are regis-tered under TSCA, with 67,317 substanceslisted in the nonconfidential inventory(USEPA, 2014a). This discrepancy occursbecause many chemical identities are pro-tected as a result of confidentiality ofbranded materials. It is interesting to notethat TSCA does not include pesticides,

pharmaceuticals, or cosmetics, so manyemerging chemical substances of concernfor water purveyors would not beaddressed by the act.

The Endocrine Disruptor ScreeningProgram (EDSP) was developed by

USEPA to screen chemicals before they are

manufactured or used in applications inwhich water and food may become con-taminated (Snyder et al, 2003). The EDSPprimarily addresses potentially adverseeffects of chemicals related to the endog-enous estrogen, androgen, and thyroidhomeostasis of animals. The EDSP uses atiered testing approach with a suite ofacute, chronic, and multigenerational bio-assays. Although comprehensive in design,the EDSP has been extremely slow toimplement. The original goal was to begin

chemical screening using the test batteryby 1999, yet the first chemicals to offi-cially enter Tier 1 screening began in 2009(Juberg et al, 2014). Beyond the timingchallenge, there also is the staggering costfactor estimated to be nearly $1 million





per chemical (USEPA, 2014b). The testing

program also may require up to 520 ani-mal lives per chemical for Tier 1 testingalone (Willett et al, 2011). Thus, it is dif-ficult to comprehend the magnitude ofcosts, in terms of money and animal lives,required for a chemical that undergoesboth Tier 1 and Tier 2 testing under theEDSP. Therefore, USEPA is includingmore high-throughput screening (HTS)for the “EDSP of the 21st Century(EDSP21),” which includes informationon the prioritization of 90 regulated

chemicals and an additional 6,000 froma “preliminary universe” (USEPA, 2011).The EDSP was designed to specificallyprotect drinking water by screeningchemicals in commerce for adverse endo-crine disruptive activity, but the processis exceedingly expensive, advancinglethargically, and still covers only a lim-ited number of potential endpoints rele-vant to the human endocrine system.

USEPA uses the Contaminant Candi-date List (CCL) as a mechanism to pri-

oritize both chemical and biological con-taminants that may require regulation indrinking water. Coupled with the Unreg-ulated Contaminant Monitoring Rule(UCMR), these programs administeredby USEPA serve to prioritize and identifyemerging contaminants in US drinkingwaters. However, because the third CCL(CCL3) universe contained approxi-mately 7,500 chemicals and the finalCCL3 contained 116, in reality only asmall subset of the true “universe” of the

chemicals potentially present in drinkingwater is ultimately prioritized for furtheroccurrence assessment and regulatoryconsideration. The UCMR requires USwater agencies to monitor for a relativelysmall number of chemicals and is specifi-cally not to exceed 30 chemicals perUCMR round.

As interesting examples, N -nitrosodi-methylamine (NDMA) and polybrominateddiphenylethers (PBDEs) represent twoextremes of chemical occurrence in the sec-

ond round of UCMR (UCMR2). NDMA

was detected in 27% of the 1,198 public

water systems tested, with maximum andaverage concentrations of 630 and 9 ng/L,respectively (USEPA, 2012). On the otherhand, PBDEs were not detected in any ofthe 3,927 public water systems tested; how-ever, the method reporting limits for PBDEsmonitored in UCMR2 ranged from approx-imately 300 to 900 ng/L (USEPA, 2012). Itis not surprising that PBDEs were notdetected in water using these methodreporting limits considering that PBDEs areextremely insoluble in water. For instance,

the aqueous solubility of PBDE-153 is only870 ng/L at 25°C (Tittlemier et al, 2002),and the UCMR2 method reporting limit(MRL) was 800 ng/L (USEPA, 2012). As amore recent example, the primary endoge-nous estrogen 17ß-estradiol (E2), whichwas included in the current UCMR(UCMR3), has not yet been detected in anyof more than 3,500 samples tested (USEPA,2014c). This situation illustrates thatalthough USEPA has developed and man-ages a rigorous program to prioritize, eval-

uate, and potentially regulate chemicals thatmay occur in drinking water, the process isrelatively slow and may not be representa-tive of the types of chemicals that are mostpervasive in US water systems.

THE SURROGATE AND INDICATOR

APPROACH

Although hundreds of chemicals havebeen detected in water, thousands morelikely occur but have not yet been detected.It is vastly infeasible to attempt monitoring

of each and every potential chemical; how-ever, a structured approach of analyzing alimited suite of representative chemicalindicators can provide valuable informa-tion on the sources contributing to a par-ticular watershed and the degree to whichthe water source may be affected (Dicken-son et al, 2011). Chemical surrogates aregenerally considered bulk parameters thatcan be relatively easily measured, often byon-line monitoring systems. Similar tomicrobial surrogates and indicators cur-

rently used for disinfection monitoring and





compliance, a representative group of

chemical surrogates and indicators can alsoprovide valuable information about treat-ment process efficacy and reliability(Drewes et al, 2013).

One pragmatic application of chemicalindicators could involve binning sourcewaters to advise the type of treatment pro-cesses that should be employed in systemsin which results show influence from pointand nonpoint source pollution. This typeof approach has already been implementedfor pathogenic microbes within USEPA’s

Surface Water Treatment Rule (SWTR),which requires utilities to conduct moni-toring of source water, producing occur-rence data that subsequently dictate theamount and/or degree of treatmentrequired (Cotton and Passantino, 2005).For chemical indicators, currently availablemass spectrometric methods provide forrapid and sensitive monitoring of a diversesuite of chemicals in only a few mL ofwater (Trenholm et al, 2009) or even less(Backe & Field, 2012). These high-speed

and robust methods rely on expensive massspectrometric instruments; however, costsare decreasing, and sensitivity is increasing.Thus, a relatively rapid assessment ofchemical indicators is possible and can beused to “bin” waters according to theirdegrees of impact. If a binning approachwere implemented for chemical constitu-ents, tremendous advancement could berealized for potable water reuse, be it defacto, indirect, or direct, by guiding watertreatment processes based on water quality

evaluations for chemicals. Such anapproach would be a prudent path for-ward in addressing emerging chemical con-taminants and protecting drinking waterregardless of source.

On-line monitoring will continue toadvance and play a critical role in under-standing source water quality changesand treatment process efficacy. Althoughthe indicator approach of measuring alimited suite of representative chemicalsprovides a highly specific view of the

types of inputs within a particular water-

shed, the analyses generally will involve

relatively sophisticated analytical equip-ment and can require days, if not weeks,for analytical results if required analyticaltechnologies are not available locally. Themonitoring of surrogate species throughon-line monitoring and/or rapid off-linetests can provide near instantaneous in-formation regarding water quality andtreatment integrity. Currently, equipmentfor on-line monitoring of parameters such

as DOC, conductivity, ultraviolet (UV)light absorbance, chlorine residual, par-

ticle count, and others are already com-mercially available and well established.

Newer technologies, such as fluores-cence, also have more recently been dem-onstrated to provide an excellent means tomonitor for changes in water quality andtreatment efficiency (Henderson et al,2009; Rosario-Ortiz et al, 2007). A majorchallenge for the implementation of desalt-ing membranes—i.e., reverse osmosis (RO)and nanofiltration (NF)—is the meager, ifany, disinfection credit awarded for these

highly efficient processes. As an example,the Texas Commission on EnvironmentalQuality (TCEQ) states that “the TCEQhas determined spiral wound membranessuch as RO, at this time, cannot be givenpathogen credit removal . . .” (TCEQ,2013). The reasons that TCEQ and otherstate regulatory authorities give little or nocredit for pathogen removal by RO andNF are primarily because of the lack ofdirect integrity tests and/or real-time mon-itoring capabilities. Technologies such as

conductivity can provide a nonselective

There is absolute certainty that more and more chemicals will

be detected in water at diminishingly minute levels as analytical

methodologies improve and commercialization of new materials evolves.





measure of membrane integrity, and fluo-

rescence recently has been demonstratedto have great promise as well (Singh et al,2012). As shown in Figure 1, the use offluorescence has also been recently appliedfor the monitoring of granular activatedcarbon and has been demonstrated to pro-vide a more selective response for predict-ing specific contaminant breakthroughs ascompared with dissolved organic carbon(DOC; Anumol et al, 2013). Technologiesfor sensors continue to advance, withrecent data demonstrating the direct mea-

surement of microbial contaminants inwater (Sherchan et al, 2014). Without

question, on-line sensing will grow expo-

nentially in the coming years and likelybe required in the permitting of directpotable reuse to ensure system integrityand reliability.

APPLICATION OF RAPID BIOASSAYS

FOR WATER QUALITY MONITORING

The canary in the coal mine was reliedon for more than 100 years by miners whoused these birds to ensure that air withinthe mine was suitable for humans tobreathe. The use of animal sentinels indeed

has a long history in protecting humanhealth. Toxicity or lethality is assessed

FIGURE 1 Fluorescence at different bed volumes for using Norit Hydro DARCO 12 × 40 GAC

BV—bed volume, GAC—granular activated carbon

300

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25291 BV


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Influent


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1245 BV

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3747 BV

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6245 BV


4996 BV


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7493 BV

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8742 BV

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9992 BV

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13738 BV

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14988 BV

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18266 BV

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22481 BV

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32551 BV


37470 BV


45744 BV





using a nonhuman animal that ideally is

more sensitive than a human to a particu-lar stressor (Boycott et al, 1908). Severalmillion animals are used annually for tox-icity testing within the United States, withnumbers sometimes exceeding 33 millionin a single year (Institute of Medicine andNational Research Council, 1988).

Currently, most regulations for contam-inants in drinking water are based on tox-icity information gained through animaltesting; however, the rapid proliferationand detection of chemicals in the aqueous

environment vastly outpace the rate atwhich chemicals can be evaluated throughtraditional animal studies. Although con-ventional dogma has held intact animaltesting—generally using rodents—as thehallmark for human toxicity evaluations,the physiology of mice and rats is dissimi-lar in many ways to that of humans. Alack of confidence in the representative-ness of animals as surrogates for humansin toxicity testing is evident in the use of asafety factor of 10 by USEPA for interspe-

cies variation in addition to a safety factorof 10 for intraspecies variability amonghumans when calculating a drinking waterequivalent level (DWEL) protective ofpublic health (Ritter et al, 2007). Unlesshuman clinical testing has been performed(i.e., pharmaceuticals) or occupationalexposure data are available (i.e., perchlo-rate), large uncertainty factors will beapplied that drive the DWEL lower by anorder of magnitude or more. As the num-ber of chemicals continues to grow and the

interest in additional endpoints of toxicityincrease and in consideration of the fore-boding issue of chemical interactions (akamixture toxicity), there is little hope thatanimal testing using conventional methodscan offer a realistic mechanism for evalu-ating emerging contaminant toxicity.

As opposed to the slow pace of tradi-tional animal testing and limitations inextrapolating from nonhuman to humanspecies, high-throughput screening (HTS)offers a wealth of information at a rela-

tively small cost. During the past few

decades, tremendous advances made in

genomics, proteomics, metabolomics, andcomputer modeling have greatly increasedour ability to assess a chemical’s potentialfor human toxicity. However, the extrapo-lation from a cellular response to anadverse effect within an intact animalremains challenging, and differentiatingbetween statistical significance and bio-logical significance of an observed effect isonerous (Tice et al, 2013). In the UnitedStates, bioassay monitoring is alreadyrequired by USEPA for wastewater dis-

charge through whole effluent toxicity test-ing requirements (Chapman, 2000). Itseems fitting that an analogous program bedeveloped for drinking water using assaysand endpoints appropriate for humanhealth. Additionally, even with the limita-tions of extrapolation from a cellularresponse to human health outcomes, HTSassays provide a more comprehensive viewof chemical constituents present in water aswell as an assessment of their cumulative(mixture) toxicity. Work conducted in the

1990s demonstrated that cellular (in vitro)bioassays could be effectively used to iden-tify substances in water that in combinationresult in observed toxicity to aquatic species(Snyder et al, 2001). A recent study hasdemonstrated that a battery of in vitroassays can be used to evaluate several path-ways of toxicity within a single water sam-ple (Escher et al, 2014).

The current risk assessment paradigm ofdiscrete chemical testing using in vivo ani-mal models cannot reasonably be expected

to address currently identified chemicals inthe aquatic environment let alone considerthe rate of development of new chemicalsynthesis and the innumerable potentialtransformation products. For instance,oxidation has been shown to significantlyreduce the concentrations of many organicconstituents, but the total organic carbonin the water is not well removed (Lee etal, 2013). This means that chemical con-stituents are not actually re moved, butrather are transformed into other struc-

tures of mostly unknown toxicity. Thus,





an important advantage of HTS assays

for water monitoring is their utility foridentifying yet unknown substances thatexert toxicity via biochemical pathways,whereas targeted analyses are limited tothose known substances for which instru-ments have been calibrated.

Equipment to perform most in vitro cel-lular bioassays is significantly less expen-sive than those required for mass spectro-metric techniques used for targetedanalyses. Although many cell bioassays areavailable commercially, USEPA continues

to develop a wide array of assays thatcould be made publically available forvery little cost to water agencies. Cell cul-ture equipment is already available inmany water laboratories, and plate-scan-ning spectrophotometers can be procuredat reasonable costs that are at least anorder of magnitude less than commonlyemployed liquid chromatography tandemmass spectrometer equipment. The prolif-eration of 384 well-plate assays along withrobotics for liquid handling also will

decrease labor and supply costs whilesimultaneously increasing reproducibility.Without question, HTS assays will con-tinue to be developed and applied forwater quality evaluations, allowing forrapid and relatively inexpensive character-ization of the mixtures of chemicals thatmay occur in water.

CHEMICAL IDENTIFICATION

AND OCCURRENCE PATTERNS USING

HIGH-RESOLUTION MASS SPECTROMETRY

Bioassays can provide a comprehensiveview of chemicals that exert bioactivity inliving systems, but they are unable to iden-tify specific chemical structures responsi-ble for observed effects. During the pastdecade, high-resolution mass spectrome-ters have become increasingly available atlower costs, allowing for full-spectrascreening of complex mixtures of chemi-cals in water (Ferrer & Thurman, 2012).Thus, these instruments allow both iden-tification and quantification of known

constituents as well as structural identifi-

cation of transformation products result-

ing from water treatment processes(Mawhinney et al, 2012). Because thesemass spectrometers gather full-spectrumdata, the resulting data can be mined forco-occurring species, identification of yetunknown chemicals, and searched ex postfacto for chemicals that may have occurredin previously analyzed samples.

Coupled with statistical spectral evalu-ation software, which has the unique capa-bility to determine occurrence patternsand disambiguate the extraordinarily large

data sets produced, high-resolution massspectrometry (HRMS) provides a power-ful tool for “fingerprinting” samples. Asan example, HRMS has been successfullyused to determine the origins of red wines(Vaclavik et al, 2011) and to measure themetabolomic response of cells to chemicalagonists (Rijk et al, 2012). Recently, thisapproach has been used to identify andtrace chemical constituents in water beforeand after various doses of ozone (Merel &Snyder, 2014). As shown in Figure 2,

through HRMS scanning and spectral pro-cessing, heat maps can be created thatshow the occurrence and fate of more than1,000 co-occurring chemical substances.Although HRMS systems are relativelycomplicated to operate and comparativelyexpensive, it is fully expected that costswill continue to decrease and operationalsoftware will become less challenging touse. Therefore, HRMS technology willbecome increasingly popular for waterquality monitoring and will allow for a

more complete screening of organic con-stituents with the important ancillary ben-efit of tracking changes in organic con-taminant profiles over time.

THE PATH FORWARD FOR EMERGING

CONTAMINANTS

Numerous federal and state programsoperate in various realms of chemicalregulation; however, it would be prudentto harmonize these efforts, focusing onchemical production and commercializa-

tion. If chemicals were thoroughly





screened with the appropriate toxicologi-

cal endpoints and at doses encompassingthose expected to occur in drinking waterunder the worst-case scenarios, and if fateand treatment studies could be performed(including evaluation of by-productsformed), water agencies could be far moreprepared if that substance was detectedwithin a source water. Perhaps mostimportant, measures could be taken torestrict or ban the use of chemicals foundto be at high risk to human health and/orhave high propensity to contaminate

drinking water sources.For chemicals already released to the

aquatic environment, a representativegroup of indicators should be used to judgethe degree and types of inputs contributingto a particular watershed. The binningapproach used for the SWTR could beexpanded to include chemical contami-nants to inform the degree of treatmentrecommended for a particular group ofchemical structures. Surrogate monitoringalso has value by providing rapid evalua-

tions, often times on-line, of water qualityconditions. Surrogates can be used to tell ifwater quality has changed and/or can beapplied within treatment systems to gaugeif the particular process or train is function-ing efficiently. A combined approach oftargeted indicator chemicals along withsurrogate measures can allow calibrationbetween a surrogate response and chemicalindicator fate. Thus, rapidly applied predic-tive tools can be developed that will allowreal-time calculation of chemical removal

or pathogen disinfection, based on bulksurrogate responses during treatment.

The quixotic paradigm of discretechemical testing at high doses and subse-quent risk assessment for the generallytrace amounts occurring in drinking wateris not feasible for addressing the millionsof chemicals in commerce, let alone themultitudinous number of transformationproducts formed during water treatment.At the forefront of science lies the criticaltask of developing rapid biological assays

and computer modeling systems that will

permit high-throughput prioritization of

the innumerable chemical structures thatcan and do occur in water supplies. Manyof the necessary tools already exist thatwill allow water quality evaluations toenter the 21st century and provide mean-ingful protection of public health byfocusing efforts on those constituents thatmay pose risk rather than those that sim-ply garner public and media attention.This author suggests that the water indus-try rapidly begin to pilot bioassay moni-toring of its water systems for those end-

FIGURE 2 HRMS heat maps of chemical constituents present inreclaimed water before and after ozonation*

0 1.5 3 4.5 5.6

Increasing Ozone Dose—mg/L

F

C

E

B

A

D

HRMS—high-resolution mass spectrometer

*A and B are chemicals attenuated/transformed by ozone; C, D, and E are chemicalsformed by ozonation; F represents chemicals recalcitrant to ozonation.





points already well established as

meaningful to human health and thosethat represent the types of chemicalsknown to occur in some water supplies(Escher et al, 2014). It is not recom-mended that bioassays be used currentlyto regulate drinking water, but rather beused to screen water to determine thetypes of chemicals and chemical mixturespresent in raw and finished waters.

HRMS will continue to grow in popular-ity and shrink in price. HRMS instrumentsare capable of broad applications, including

routine targeted analysis, identification oftransformation products, and creating com-prehensive databases from sample analysesthat can be retroactively mined to determineif the “contaminant du jour” was presentwhen a sample was collected and analyzed,even years or decades later. Thus, HRMSinstruments can obtain and store complexmass spectral data for samples that can beused to create heat maps, conduct statisticalanalyses, and serve as a data archive forfuture exploration. When coupled with bio-

assay screening, HRMS provides the meansby which causative agents can be identifiedand quantified. HRMS instruments are cur-rently expensive and complex to operate;however, the prices are rapidly descending,and the software for operation is becomingmore user friendly. It is likely that HRMSsystems will be adopted into water labora-tories in the foreseeable future.

FINAL THOUGHTS

Many water agencies and professionals

feel beleaguered by the expanding lists ofchemical contaminants detected in waterand growing concerns regarding previ-ously underexplored mechanisms of toxic-ity. These feelings can be exacerbated bythe obfuscation of the issues through dra-matized media reports and other nonsci-entific communications regarding poten-tial risks. Paradoxically, the US waterindustry and associated research founda-tions were among the first to fund, con-duct, and report the efficacy of treatment,

occurrence, and toxicological relevance of

pharmaceuticals and other emerging con-

taminants in US water supplies (Bruce etal, 2010; Benotti et al, 2009; Westerhoff etal, 2005). The water industry should bevery proud of the numerous avant-garderesearch projects on emerging contami-nants conducted in the absence of regula-tory requirements and the transparencythat allowed publication of findings inreadily available manuscripts and reports.

Many regions are facing imminentwater supply shortages as the result ofchanges in historical precipitation patterns

and from population growth and density.To expand water supplies beyond what isavailable from natural sources, waterimportation, salt water desalination, andwater reuse are essentially the onlyoptions. Potable water reuse seems to bemaking the greatest gains in terms of num-ber of projects under consideration andmay be the only viable option for someinland communities. Although emergingcontaminants are often among the greatestconcerns of the public and some regulators

when discussing potable water reuse, thecurrently engineered and demonstratedpotable water reuse systems produce waterquality far better than what most of thenation’s population consumes. Thethought of drinking another person’swaste will not be broadly appealing, butthe reality is that we frequently reuse itemssuch as hotel sheets, restaurant silverware,and surgical instruments. None of theseitems is simply discarded after a single use,but instead is cleaned, disinfected, and

prepared for use again. The same generalconcept is applicable to water. It can becleansed for reuse using existing treatmenttechnologies to remove chemicals and dis-infect microbes to provide water morepure than even nature could provide.

There is absolute certainty that moreand more chemicals will be detected inwater at diminishingly minute levels asanalytical methodologies improve andcommercialization of new materialsevolves. Source waters for potable reuse

will have a plethora of chemicals, both

Congratulations to JOURNAL

AWWA on its important

anniversary! The JOURNAL was a

critical resource during my

graduate studies, both for its

content and for its inspiration

to pursue a career in the water

resources field. Many journals

include timely and cutting-edge

research; however, few—if

any—journals provide the

same forum for community

engagement and community

conversation. For me, as a

young professional, JOURNAL

AWWA continues to inform and

shape my career. I look forward

to reading and contributing to

the JOURNAL for many years

to come!

—Craig Aubuchon, Associate,

Analysis Group Inc.





regulated and nonregulated, but achieving

safe and reliable water is possible throughextensive treatment and rigorous monitor-ing to detect and correct any drift fromexpected performance. Greater harmonyresults from a comprehensive approach.

ACKNOWLEDGMENT

The author would like to thank ErinSnyder from Total Environmental Solu-tions Inc. for her kind help in reviewingand editing the manuscript. In addition,the author acknowledges and thanks

Tarun Anumol and Sylvain Merel fromthe University of Arizona for providingthe data and graphics for Figures 1 and 2,respectively. This research was supportedby National Institute of EnvironmentalHealth Sciences grant P30 ES06694 to theSouthwest Environmental Health SciencesCenter at the University of Arizona. Sny-der has also been supported by the Singa-pore National Research Foundationunder its Environment and Water Tech-nologies Strategic Research Programme

and administered by the Environment andWater Industry Programme Office of thePublic Utility Board. The content of thismanuscript is solely the responsibility ofthe author and does not necessarily rep-resent the official views of the NationalInstitutes of Health.

ABOUT THE AUTHOR

Shane A. Snyder is professor of chemical

& environmental engineering at the

University of Arizona’s College of

Engineering and visiting professor at theNational University of Singapore,

Environmental Research Institute. Snyder

co-directs the Arizona Laboratory for

Emerging Contaminants and the Water &

Energy Sustainable Technology Center at

the University of Arizona. Snyder has

published more than 150 manuscripts and

book chapters and serves as an editor-in-chief for the international journal

Chemosphere. He is a member of USEPA’s

Science Advisory Board drinking water

committee and was recently appointed to

the World Health Organization’s Drinking

Water Advisory Panel. Snyder is also avisiting professor at the National

University of Singapore. He has more than

20 years of experience in the evaluation

and characterization of water

contaminants, including 10 years as the

research and development project manager

for the Southern Nevada Water Authority.

http://dx.doi.org/10.5942/jawwa.2014.106.0126

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43:4:863. http://dx.doi.org/10.1016/j.watres.2008.11.027.

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Institute of Medicine and National Research Council,1988. Use of Laboratory Animals in Biomedical

and Behavioral Research. The National

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Juberg, D.R.; Borghoff, S.J.; Becker, R.A.; Casey, W.;

Hartun, T.; Holsapple, M.P.; Marty, M.S.; et al,2014. Lessons Learned, Challenges, andOpportunities: The US Endocrine DisruptorScreening Program. Altex-Alternatives to

Animal Experimentation, 31:1:63.

Kidd, K.; Blanchfield, P.J.; Mills, K.H.; Palace, V.P.;Evans, R.E.; Lazorchak, J.M.; & Flick, R.W., 2007.Collapse of a Fish Population After Exposure toa Synthetic Estrogen. Proceedings of the

National Academy of Sciences, 104:21:8897.http://dx.doi.org/10.1073/pnas.0609568104.

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Health Perspectives, 115:S1:98. http://dx.doi.org/10.1289/ehp.9357.

Lee, Y.; Gerrity, D.; Lee, M.; Bogeat, A.E.; Salhi, E.;Gamage, S.; Trenholm, R.A.; Wert, E.C.; Snyder,S.A.; & von Gunten, U., 2013. Prediction ofMicropollutant Elimination During Ozonation ofMunicipal Wastewater Effluents: Use of Kineticand Water Specific Information. Environmental

Science & Technology, 47:11:5872. http://dx.doi.org/10.1021/es400781r.

Locke, P.A. & Myers, D.B., 2010. Implementing theNational Academy’s Vision and Strategy forToxicity Testing: Opportunities and Challenges

Under the U.S. Toxic Substances Control Act.Journal of Toxicology and Environmental

Health-Part B-Critical Reviews, 13:2-4:376.http://dx.doi.org/10.1080/10937404.2010.483952.

Mawhinney, D.B.; Vanderford, B.J.; & Snyder, S.A.,2012. Transformation of 1H-Benzotriazole byOzone in Aqueous Solution. Environmental

Science & Technology, 46:13:7102. http://dx.doi.org/10.1021/es300338e.

Melchert, M. & List, A., 2007. The Thalidomide Saga.International Journal of Biochemistry & Cell

Biology, 397-8:1489. http://dx.doi.org/10.1016/j.biocel.2007.01.022.

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Novak, P.J.; Arnold, W.A.; Blazer, V.S.; Halden, R.U.; Kla-per, R.D.; Kolpin, D.W.; Kriebel, D; et al, 2011. On theNeed for a National (US) Research Program to Elu-cidate the Potential Risks to Human Health and theEnvironment Posed by Contaminants of EmergingConcern. Environmental Science & Technology,

45:9:3829. http://dx.doi.org/10.1021/es200744f.

Richardson, S.D. & Ternes, T.A., 2014. WaterAnalysis: Emerging Contaminants and CurrentIssues. Analytical Chemistry, 86:6:2813.

http://dx.doi.org/10.1021/ac500508t.

Continued on page 52

The JOURNA l – American

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membership. It educates andprovides technical and policy

underpinnings for water

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and it chronicles the rapid

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members and for posterity. It

is an essential member of the

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team. You can’t call yourself awater professional and not be

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—Joseph A. Cotruvo, Joseph

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Rijk, J.C.W.; Peijnenburg, A.A.C.M.; Blokland,

M.H.; Lommen, A.; Hoogenboom, R.L.A.P.; &Bovee, T.F.H., 2012. Screening for ModulatoryEffects on Steroidogenesis Using the HumanH295R Adrenocortical Cell Line: AMetabolomics Approach. Chemical Research

in Toxicology, 25:8:1720. http://dx.doi.org/10.1021/tx3001779.

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Health-Part B-Critical Reviews, 10:7:527.http://dx.doi.org/10.1080/15287390600975178.

Rosario-Ortiz, F.L.; Snyder, S.A.; & Suffet, I.H., 2007.

Characterization of Dissolved Organic Matter inDrinking Water Sources Impacted by MultipleTributaries. Water Research, 41:18: 4115.http://dx.doi.org/10.1016/j.watres.2007.05.045.

Sherchan, S.P.; Snyder, S.A.; Gerba, C.P.; & Pepper,I.L., 2014. Online Monitoring of Escherichia coli

and Bacillus Thuringiensis Spore InactivationAfter Advanced Oxidation Treatment. Journal of

Environmental Science and Health, Part A:

Toxic/Hazardous Substances & Environmental

Engineering, 498:933. http://dx.doi.org/10.1080/10934529.2014.893793.

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Snyder, S.A.; Westerhoff, P.; Yoon, Y.; & Sedlak, D.L.,2003. Pharmaceuticals, Personal Care Products,

and Endocrine Disruptors in Water: Implicationsfor the Water Industry. Environmental

Engineering Science, 20:5:449. http://dx.doi.org/10.1089/109287503768335931

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Toxicology and Chemistry, 21:9:1804.http://dx.doi.org/10.1002/etc.5620210907.

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Acta, 685:1:45. http://dx.doi.org/10.1016/j.aca.2010.11.018.

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Technology, 39:17:6649.http://dx.doi.org/10.1021/es0484799.

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