Emerging compounds: A concern for water and · PDF filerisk to humans has been demonstrated from exposure to EDCs in drink-ing water. EDCs have, ... Emerging compounds: A concern for

ater utilities have come under increasing scrutiny as the agen-cies responsible for controlling human exposure to pharma-ceuticals, endocrine-disrupting chemicals, and other com-pounds of emerging concern (CECs) in drinking water. For example, a recent investigation by the Associated Press (Donn

et al, 2008) reported on the presence of pharmaceuticals in the drinking water of 24 major US metropolitan areas. This report prompted public concern and put additional pressure on water utilities to respond to what was presented as a threat to public health.

Most CECs are likely benign to humans at the concentrations detected in the environment and in drinking water. They continue to be of concern, however, because some of the compounds that have been detected are endocrine disrupting chemicals (EDCs). EDCs can have effects on the human endocrine system at extremely low concentrations, although no risk to humans has been demonstrated from exposure to EDCs in drink-ing water. EDCs have, however, been implicated in adverse effects in aquatic organisms that are exposed to wastewater in the environment. There is also evidence that some CECs that are not EDCs demonstrate toxicity with more traditional endpoints toward aquatic organisms (such as growth inhibition or change in behavior), even at enviornmentally relevant concentrations. There is also evidence that some CECs that are not EDCs demonstrate toxicity with more traditional endpoints toward aquatic organisms, even at environmentally relevant concentrations.

Wwastewater utilities

Emerging compounds: A concern for water and

One way compounds

of emerging concern

can enter the environment

is through wastewater

treatment plant effluent.

A LT H O U G H M O R E R E S E A R C H N E E D S

T O B E C O N D U C T E D R E G A R D I N G

T H E E F F E C T S O F C O M P O U N D S

O F E M E R G I N G C O N C E R N ,

I T I S L I K E LY T H A T T H E S E

C O M P O U N D S R E P R E S E N T T H E N E X T

R E A L M O F R E G U L A T O R Y C O N C E R N .

50 NOVEMBER 2008 | JOURNAL AWWA • 100 :11 | FONO & MCDONALD

emerging issues

B Y L O R I E N J . F O N O A N D H . S T E P H E N M C D O N A L D

2008 © American Water Works Association

FONO & MCDONALD | 100 :11 • JOURNAL AWWA | NOVEMBER 2008 51

Although more research needs to be conducted regarding the effects of CECs on human and aquatic health, it is likely that these compounds rep-resent the next realm of regulatory concern and that their removal will drive the research agenda and the selection of water and wastewater treatment processes in the future.

CECs ARE UBIQUITOUS DOWNSTREAM OF WASTEWATER DISCHARGES

Although many CECs have been present in the environment for decades, concern about their possible effects on humans and wildlife is being driven by improved analytical techniques that are able to detect them at increasingly lower concen-trations. In general, these com-pounds are present at trace concen-trations (i.e., parts per trillion or less) in complex mixtures.

CECs encompass a large number of compounds (Table 1). Com-pounds can be grouped either by their intended use—such as phar-maceutical products or surfac-tants—or by their potential envi-ronmental or human health effects. For example EDCs, which interfere with human or animal hormonal function, sometimes even at very low levels, comprise trace constitu-

ent classes such as pharmaceuticals, personal care products, detergent metabolites, plasticizers, bromi-nated flame retardants, and pesti-cides. Additionally, individual com-pounds within a class can have significantly different toxicities and removal rates within wastewater treatment plants (WWTPs) and in the environment.

CECs have been detected in sur-face waters and groundwater down-stream or downgradient of wastewa-ter discharges. Much of the early occurrence survey work was con-ducted in Europe—particularly Ger-many and Switzerland—where high population densities and low per capita water use result in relatively high concentrations of CECs in wastewater and receiving waters. Even illegal drugs such as cocaine are detectable in some surface waters that are affected by wastewater (Zuccato et al, 2005).

There has been, and continues to be, a significant amount of investiga-tion into the presence of CECs in the environment in North America. For example, Kolpin and colleagues (2002) at the US Geological Survey (USGS) performed a survey of trace organic contaminants in US surface waters and detected 82 of 95 indi-vidual CECs on their analyte list,

with low levels detected in almost all samples. As a testament to the atten-tion this topic has been attracting, the resulting article was the most downloaded article ever published in Environmental Science and Technol-ogy (Kolpin et al, 2002).

David Sedlak, a professor at the University of California at Berkeley and the principle investigator of an Awwa Research Foundation–spon-sored occurrence survey of phar-maceuticals in wastewater effluent, has been researching the fate and transport of CECs over the past decade. “At this point, it’s not whether we can find them. We see them everywhere. The question now is whether they’re having adverse effects on wildlife popula-tions, and what can we do about it,” Sedlak said.

CECs IN WASTEWATER ADVERSELY AFFECT AQUATIC ORGANISMS

There has been growing attention during the past several years from the public and the scientific and wastewater communities on the potential ecological effects of trace constituents. For example, during the past two years, significant media coverage was given to reports that up to 100% of the male smallmouth bass in some sections of the Chesa-

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TABLE 1 Trace constituents in wastewater

Class of Compound

Typical Concentration

in EffluentPotential Ecological

or Human Health Effects Examples

Pharmaceuticals Up to 1 µg/L Endocrine disrupting Antibiotics, painkillers, caffeine, birth-control pill, antiepileptics

Personal care products Up to 1 µg/L Bioaccumulative, endocrine disrupting Soaps, fragrances, triclosan

Detergent metabolites Up to 180 µg/L Bioaccumulative, endocrine disrupting Ocylphenol, nonylphenol

Plasticizers Up to 10 µg/L Weakly endocrine disrupting Phthalate esters, bisphenol A

Perfluorooctane surfactants Up to 1 µg/L None at environmentally relevant concentrations

Stain-resistant coating for clothing and furniture

Brominated flame retardants Up to 30 mg/L Bioaccumulative, suspected endocrine disruptors

Polybrominated diphenyl ethers

Disinfection by-products Up to 1 µg/L Carcinogenic N-nitrosodimethylamine



peake Bay watershed are intersex (Associated Press, 2006).

Wildlife are exposed to CECs and EDCs in effluent-dominated streams or by eating plants or animals in which these substances have bioaccumulated. Aquatic organisms have a greater risk than humans because they have greater exposure. Although many of these compounds undergo natural attenua-tion in the environment because they are being constantly discharged, organisms that are exposed to them experience a “pseudopersistence.”

Recent research has examined the effects of CECs and EDCs on wildlife both in the lab and in the field. In many species this research has shown a causal relationship between expo-sure to human and synthetic hor-mones, plasticizers, and detergent metabolites and the induction of an egg protein in male fish, for example. Intersex fish found downstream of WWTPs have been linked to estroge-nicity in wastewater discharges (Har-ries et al, 1996).

Most significant, in a seven-year study in the Experimental Lakes Area in northern Ontario the popu-lation of fathead minnow exposed to a low but constant concentration of the hormone found in birth control pills ultimately collapsed (Kidd et al, 2007). Although these specific results cannot be immediately extrapolated to other species and watersheds, there is cause for concern.

THE SPOTLIGHT ON WATER UTILITIES IS DRIVEN BY HUMAN HEALTH CONCERNS

Potential human health effects resulting from exposure to CECs are harder to detect than effects on wild-life. Humans are exposed to pharma-ceuticals and endocrine-disrupting chemicals through various routes. For example, fat-soluble compounds such as flame retardants or PCBs can be consumed by eating aquatic animals in which they have bioaccumulated, and water-soluble compounds such as most pharmaceuticals for humans can be consumed in drinking water. This latter route is of concern to the drinking water industry.

Research is just beginning to ad -dress questions about effects of chronic low-level exposure, including possible synergism and other toxico-logical factors associated with these compounds. It is difficult to predict the effects of chronic exposure to extremely low concentrations of a contaminant; generally, tests are done with higher concentrations than occur in drinking water, using other mammalian species, and the effects are extrapolated to lower concentra-tions using a dose–response curve. A safety factor is then applied to account for the differences between humans and the test species. Some toxicity studies are conducted by exposing hu man tissue cultures in vitro to the compounds being exam-

ined. Neither of these types of exper-iments provides conclusive evidence about the human health effects of exposure to parts-per-trillion levels of pharmaceuticals in drinking water.

The constituents of greatest potential concern to humans are the EDCs mentioned previously, because of possible effects at very low concentrations. They also pose a disproportionate threat to fetal development and young children because they interfere with normal developmental chemical signals in the body. Therefore, it is not just the level of exposure of EDCs that cause concern, it is also the timing of the exposure during the develop-ment of humans and animals.

The potential human health ef -fects of EDCs are being studied by many groups, including the US Envi-ronmental Protection Agency (USEPA). The endpoints of exposure to pharmaceuticals and EDCs in water that are being considered by researchers include endocrine system effects, neurological problems, re -productive and developmental ab -normalities, and cancers.

Many researchers point out that the quantity of estrogens that may be consumed in reclaimed water is tiny compared with phytoestrogens and estrogenic hormones naturally present in the human diet. In fact, risk assessments that have been per-formed on drinking water to date

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have not shown an unacceptable risk to humans (Snyder, 2007). However, most re searchers currently agree that there are many unknowns regarding possible synergistic effects and long-term chronic exposure to low levels of complex mixtures of these compounds.

REGULATORY REQUIREMENTSFOR CECs ARE ON THE HORIZON

Regulations can control the input of CECs into the environment and drinking water in two ways:

• by restricting which chemicals can be marketed and therefore make their way into the waste stream and

• by setting wastewater effluent and drinking water concentration lim-its for individual compounds or bulk parameters such as estrogenicity.

So far, regulators have been more inclined to pursue the first option because toxic effects can more read-ily be shown in the parent product, rather than diluted in wastewater or drinking water.

European countries are further along than the United States in phas-ing out endocrine disruptors. Nor-way, for example, has banned the production, import, distribution, and most uses of nonylphenol and octylphenol ethoxylates. These are surfactants that have been shown to contribute significant estrogenicity to rivers downstream of industrial wastewater discharges. Additionally, the European Union requires the submission of Environmental Risk Assessments (ERAs) to gain market approval for new pharmaceuticals. These ERAs focus on the removal

rate of the compounds as well as their behavior and effects in the environment once introduced. In Canada, a similar requirement is under consideration.

The United States has already banned the use of some known endo-crine disruptors, such as PCBs, DDT,

and chlordane. However, these com-pounds were banned because of their carcinogenic effects rather than their estrogenic effects. In 1996, Congress passed new legislation requiring the USEPA to determine whether certain substances may have an effect in humans that is similar to effects pro-duced by a naturally occurring estro-gen or other such endocrine effects. In response, USEPA developed the Endo-

crine Disrupter Screening and Testing Advisory Committee (EDSTAC), whose members include representa-tives of academia, industry, public health interests, water providers, and various state and federal agencies.

In its 1998 final report, EDSTAC recommended a priority-based tiered screening system to evaluate chemi-cals for endocrine-disrupting effects. However, this program has received little funding, and the past 10 years have seen little progress on the screening of suspected EDCs.

So far, neither the USEPA nor regulators in other countries have released any guidance about the effects of relevant levels of most trace constituents in drinking water. US regulatory action at the federal level has been delayed until more research has been done because most existing data on listed man-made chemicals focus on cancer risks, and CECs are generally present at con-centrations too low to trigger con-cerns about carcinogenicity.

In response to the Associated Press article on pharmaceuticals in drink-ing water, a hearing on “Pharmaceu-ticals in the Nation’s Water: Assessing Potential Risks and Actions to Address the Issue” was held in April

Although many of these compounds undergo natural attenuation in the environment, because they are being constantly discharged organisms that are exposed to them experience a “pseudopersistence.”

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FIGURE 1 CEC removal during membrane filtration improves as pore size is reduced

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2008 by the Senate subcommi t t e e on Transportation Safety, Infrastructure Security, and Water Quality. Although not resulting in immediate regula-tory action, this hear-ing demonstrates that the issue has caught the attention of US sena-tors, which may provide impetus for further regulatory developments.

US state regulators are beginning to move ahead with adopting crite-ria, absent a federal mandate to do so. Several states, such as Massachu-setts and California, have adopted water quality criteria for perchlo-rate, a CEC that is found in rocket fuel and other explosives that has been shown to interfere with fetal development at extremely low con-centrations. Massachusetts intends to use the process it developed to regulate perchlorate to move ahead with examining possible limits for a list of 100 pharmaceuticals and per-sonal care products.

Other agencies, although not yet ready to set drinking water limits for CECs, are beginning to require that they be monitored in anticipa-tion of possible future require-ments. For example, the California Department of Public Health (CDPH) updated its Groundwater Recharge Reuse Draft Regulations Criteria in August 2008 to include project-specific monitoring require-

ments for endocrine disruptors and pharmaceuticals as well as CEC indicator compounds or surrogates in recycled water and groundwater recharge projects.

The link between CECs in waste-water and adverse ecological effects is stronger than is the link between CECs in drinking water and human health effects and therefore has attracted more attention for possible regulation at the federal level. The USEPA (2008) recently released a draft white paper concerning the development of criteria for CECs. In this document, USEPA acknowledges the difficulty of adopting criteria for constituents with nontraditional endpoints related to endocrine dis-ruption and begins to detail a frame-work to address this challenge.

Future regulatory action is likely as research progresses, and, once officially identified, industrial chem-icals and personal care products that are strong endocrine disruptors will probably be phased out of use. In the meantime, wastewater treatment facilities could be regulated for

release of suspected endocrine dis-ruptors to the environment to pro-tect aquatic habitats. In the future, it is likely that drinking water criteria will be developed for some CECs. Therefore, master planning studies for both water and wastewater facil-ities would be advisable to address the possibility of new regulations when making long-term (10- to 20-year) plans.

SCIENTIFIC RESEARCHAND PILOT TESTING ARE LEADING TO CEC REMOVAL SOLUTIONS

Both water and wastewater treat-ment can provide a barrier that pre-vents the introduction of CECs into drinking water. However, for the protection of aquatic life, the pre-ferred barrier is removal during wastewater treatment. Although most wastewater treatment plants are not specifically designed to re -move trace constituents, the major-ity of these compounds are removed at least partially during conventional wastewater treatment.

One of the most effective ways of increasing the removal of trace con-stituents during biological wastewa-ter treatment is to increase the sludge-retention time to at least 15 days or more. Under these conditions Clara and co-authors (2005) found that most pharmaceuticals, surfactants, and plasticizers are removed to below the limit of detection. Concentrations of human estrogens are reduced by 90–100% with high sludge-retention times. In fact, removal rates depend more on the sludge-retention time than on the treatment technology, because trace constituents are re -moved equally in an activated sludge process such as a membrane bioreac-tor. For treatment plants with excess capacity, sludge-retention times can be in creased by changing operating procedures without additional capi-tal investment.

Several advanced treatment tech-nologies have been shown to be effec-tive for removing trace constituents from wastewater. Filtration through granulated activated carbon (GAC),

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Of the advanced treatment

technologies, ozonation

removes the greatest

percentage of compounds

of emerging concern,

for the lowest unit cost.



advanced oxidation, and membrane treatment have all been studied to determine how well they remove trace constituents. Table 2 provides a summary of the removal efficiencies for CECs by different technologies.

An advanced oxidation technique that is being studied for removing trace constituents is the irradiation of filtered wastewater with ultravio-let (UV) light after hydrogen perox-ide has been added. This process generates free hydroxyl radicals that react quickly and nonspecifically with organic constituents in waste-water. In a study by Rosenfeldt et al (2004), two common hormones in wastewater were more than 95% removed from lab water with a con-centration of 15 mg/L hydrogen per-

oxide and either a low- or medium-pressure UV lamp.

Ozonation is often put forth as a good technique for oxidizing trace contaminants in wastewater. A l-though ozone reacts preferentially with some compounds depending on their structure, it can also react with natural organic matter to form hy droxyl radicals and indirectly oxi-dize a greater number of constituents. Hormones are among the compounds that react well with ozone, as do most pharmaceuticals that have been tested. Ozone is effective at oxidizing some of the most frequently detected trace constituents, such as carbam-azepine (an antiepileptic drug), caf-feine, cotinine (a nicotine metabolite), and atrazine (a pesticide).

With respect to advanced oxida-tion, both UV/peroxide and ozona-tion are good treatment technologies for trace constituents. Both, also pro-vide disinfection for wastewater, and improve its aesthetic qualities. How-ever, several analyses have shown that ozone can provide removal at a lower cost (Ternes et al, 2007).

In general, trace constituent removal is poor during sand filtra-tion. However, with chemical addi-tion prior to sand filtration, Salveson et al (2007) showed that the increased particle size can im prove removal to 70% for some of the more hydro-phobic compounds such as hor-mones. This can be an economical treatment strategy for WWTPs that already practice sand filtration.

TABLE 2 Summary of CEC removal by a suite of treatment technologies

Classification AS AC BAC 03/AOPs UV Coagulation/Flocculation

Softening/Metal Oxides NF RO

Pesticides

Industrial chemicals

Steroids

Metals

Inorganics

Organometallics

Antibiotics

Antidepressants

Anti-inflammatory

Lipid regulators

X-ray contrast media

Psychiatric control

Synthetic musks

Sunscreens

Antimicrobials

Surfactants/detergents

Adapted from Snyder et al, 2003

AS—activated sludge. AC—activated carbon, BAC—biological activated carbon, CEC—compounds of emerging concern, NF—nanofiltration, O3/AOP—Ozone/advanced oxidation processes, RO—reverse osmosis, UV—ultraviolet irradiation

= > 90% Removed

= 40–70% Removed

= < 40% Removed


56 NOVEMBER 2008 | JOURNAL AWWA • 100 :11 | FONO & MCDONALD 555655556566666566666666665566556666666 NO NONONONNOOONONO NNNN VEMVVVVEMVEMBER 20008

In membrane filtration, water and wastewater are pushed through tiny pores at high pressure to reject par-ticles that are not desired in the per-meate. Microfiltration (MF) and nanofiltration (NF) have progres-sively decreasing pore sizes and require increasing pressure for opera-tion, with reverse osmosis (RO) hav-ing the smallest pore size and the highest pressure.

MF rejects relatively fewer com-pounds than NF or RO because

most trace constituents are smaller than the MF membrane's pore size, although some hydrophobic com-pounds are excluded through ad -sorption. NF performs better than MF with most compounds because NF membrane pores are small enough to reject many compounds based on size, but NF is expensive. RO removes most compounds with a very high efficiency except for NDMA, which is small, polar, and behaves like a water molecule. However, although RO removes most constituents to below the limit of detection, its capital and operat-ing costs are ex tremely high.

SOURCE CONTROLIS AN ATTRACTIVE OPTIONFOR REDUCING EDCsIN THE WATER CYCLE

Cash-strapped utilities may not have the means to implement ad vanced treatment to remove unreg-ulated constituents from their waste-water or drinking water. Addition-ally, with recent focus on climate change and carbon footprints, the

cost of advanced treatment can be counted in carbon dioxide emissions as well as dollars (Jones et al, 2007). Therefore, source control is being looked at as an alternative for reduc-ing the concentrations of CECs in the environment and in drinking water.

Although the potential for CEC re duction in wastewater is much smaller for some compounds through source control than through ad vanced treatment, it is an immedi-ate step that can be taken by local

governments and utilities that does not require facility upgrades or changes in operational procedures. Source control can include the fol-lowing measures:

• Pharmaceutical take-back pro-grams to prevent the practice of flushing unneeded or expired pills. It is estimated that a maximum of 8% of pharmaceuticals are flushed down the toilet and that removing this source would lead to an approxi-mately 9% reduction in surface water loading (Tischler et al, 2007).

• Ecolabeling of household and personal care products to encourage consumers to choose products with nonpersistent, nontoxic ingredients. Regulatory oversight would be needed to allow products to claim ecofriendliness on their labels.

• Reduction of over- and unnec-essary medication. This has already been recommended to prevent the development of antibiotic-resistant bacteria and could also help reduce concentrations of CECs

• Requiring ERAs for new phar-maceutical products and phasing out

persistent or toxic pharmaceuticals when there is another compound that could have the same benefit without a toxic effect.

Thus far, source control efforts have focused on pharmaceutical take-back programs. Several states have initiated such programs with great success—as measured by the quantity of unused drugs that have been recovered. Although most drugs enter the water cycle via human excretion, these programs can re -move a portion of the loading to WWTPs and have additional benefits such as reducing accidental prescrip-tion drug poisoning and misuse.

Source control efforts require edu-cational campaigns to inform and engage the public. Because the South-ern Nevada Water Authority (SNWA) has led or been involved with much of the scientific work related to the low-level detection, treatment, and health effects associated with phar-maceuticals and EDCs in drinking water supplies, the agency has been at the forefront of communication about this topic. “By educating the public about the proper disposal of all types of chemicals—from house-hold solvents and pesticides to unused pharmaceuticals—utilities are en -couraging their customers to become stewards of both their water resources and the environment,” said J.C. Davis, the senior public information coordinator at SNWA.

Source separation is another alternative that could be considered to reduce CECs in wastewater. The most feasible means of achieving this goal is to provide onsite advanced treatment to hospital wastewater, which is a significant point source of pharmaceutical discharges to waste-water treatment plants.

LOOKING AHEADAND MOVING FORWARD

Members of the public will con-tinue to demand that the issue of CECs in the environment and in drinking water be addressed by their utilities, even in the absence of regu-latory guidance. A coherent ap -

Most researchers currently agree that there are many unknowns regarding possible synergistic effectsand long-term chronic exposure to low levels of complex mixtures of these compounds.



proach for treatment and control of CECs, as well as a communication strategy, is necessary to assure the public that the issue of pharmaceuti-cals in drinking water is being consid-ered and addressed by their water purveyors and that aquatic life is being protected by wastewater dischargers.

Clearly, there is the need for more research and continued research fund-ing until the risks from CECs are understood and addressed. Shane Snyder, a scientist at the SNWA, who has contributed significantly to knowledge about the treatment and effects of CECs, emphasizes the need for continued research. “As a scien-tist, I recommend we focus on research related to health effects from trace pharmaceuticals with a lesser emphasis on occurrence, in order to determine whether there is in fact a problem to solve. The critical ques-tion we must address is not ‘Do they exist?’ but rather, ‘At what concentra-tion are these compounds harmful to

human health?’ Only then can we make intelligent, rational decisions that protect the health of this coun-try’s municipal water customers.”

CECs are an issue for both water and wastewater utilities. AWWA mem bers and member utilities should en courage cooperation among water and wastewater organizations, such as AWWA and WEF, to provide lead-ership and dialog for the develop-ment of standards and mutual poli-cies to prevent and treat CECs in the water cycle.

ABOUT THE AUTHORSLorien J. Fono (to whom corre-spondence should be addressed) is an engineer with Car-ollo Engineers, 2700 Ygnacio Val-ley Rd., Ste. 300,

Walnut Creek, CA 94598;[email protected]. Fono received

her master’s and doctorate degrees in environmental engineering from the University of California at Berkley. She was awarded the Graduate Student Research Paper Award from the American Chemi-cal Society’s Environmental Chem-istry Division and has had articles published in Environmental Chem-istry and Technology and Water Environment Research. At Carollo she has worked in an advisory capacity on projects to treat emerg-ing contaminants in drinking water and wastewater. She also has pro-vided support for other firms that need an emerging contaminant component to their environmental impact reports. She is a member of the Water Environment Federation and has participated in drafting its literature reviews and Technical Practice Updates on emergingcontaminants. H. StephenMcDonald is a partner withCarollo Engineers.

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Donn, J.; Mendoza, M.; Pritchard, J., 2008. AP Prove Finds Drugs in Drinking Water. Associated Press, New York.

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