Emerging Contaminants

5.3.8 Emerging Contaminants

Thanks to the advancements of the communication age and the widespread use of the Internet, the public around the globe is becoming increasingly informed about various environmental concerns almost instantaneously. Traditional media is following this trend by also publishing on the Internet. The end result is an ever-increasing transparency when it comes to discussing the effects of environmental degradation on drinking water resources. The following quotes from an article published in the Las Vegas Sun illustrate this point and the role of media (October 20, 2006. Chemicals cause changes in fish and raise concerns for humans, by Launce Rake):

There’s something wrong with the fish. It’s been confounding scientists for years: Male fish are devel- oping female sexual characteristics in Lake Mead and other freshwater sources around the country. On Thursday, the U.S. Geological Survey released a four-page summary of more than a decade of studies linking wastewater chemicals to those changes. But a scientist who has studied the issue for years complains that the report understates the danger of those toxins at Lake Mead and elsewhere. The researcher had aired his concerns seven months ago—shortly after he was fired by the USGS.

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The federal agency says the researcher was fired for failing to publish his data. The researcher says the federal agency wouldn’t allow him to publish. Both sides, however, agree on the basic issue: In Lake Mead and in other freshwater sites, scientists have found traces of pharmaceuticals, pesticides, chemicals used in plastic manufacturing, artificial fragrances and other substances linked to changes in fish and animals. Thursday’s report noted that the primary source for the chemicals in Lake Mead was the Las Vegas Wash, a man-made river made up almost entirely of treated wastewater from cities in the Las Vegas Valley.

Gross said the problem is acute in Lake Mead and in other freshwater sites. One element left out of the Thursday report is evidence of sperm failure in fish, he said. “On a national scale we see alterations in fish,” said the scientist, who continues to research hormone-disrupting chemicals in Florida and other states. “Endocrine (a hormone) disruption is widespread across the United States and is widespread in Lake Mead.” Gross said his conclusions, shared by other researchers, are not popular: “The (Southern Nevada) Water Authority doesn’t want to hear it. My agency doesn’t want to hear it. The Department of Interior does not want to deal with it. They want to make the argument that there is nothing to worry about, but common sense just suggests it is not that simple.”

Studies documenting sexual abnormalities in fish in the Potomac River—source of drinking water for millions in the Washington, D.C., area—raised similar concerns in September. Water officials there said the studies showed no evidence that drinking water was unsafe, but the studies did not answer the question on potential impacts to human health.

The preceding quotes are an example of public concern with emerging contami- nants—the constituents that are generally not regulated but whose relatively wide pres- ence in drinking water supplies has been documented. The 1996 Amendments to the Safe Drinking Water Act specify that development of new drinking water standards requires broad public and scientific input to ensure that contaminants posing the greatest risk to public health will be selected for future regulation. A contaminant’s presence in drink- ing water and public health risks associated with a contaminant must be considered in order to determine whether a public health risk is evident. In addition, the new contam- inant selection approach explicitly takes into account the needs of sensitive populations such as children and pregnant women. Under the 1996 Amendments, the CCL guides scientific evaluation of new contaminants. Contaminants on the CCL are prioritized for regulatory development, drinking water research (including studies of health effects, treatment effects, and analytical methods), and occurrence monitoring. The Unregulated Contaminant Monitoring Rule (UCMR) guides collection of data on contaminants not included in the National Primary Drinking Water Standard. The data are used to evalu- ate and prioritize contaminants that the USEPA is considering for possible new drinking water standards. Currently, there are 37 SOCs on the USEPA’s CCL (USEPA, 2005c).

It is important to note that the USEPA has not limited itself to making regulatory determinations for only those contaminants on the CCL. The agency can also decide to regulate other unregulated contaminants if information becomes available, showing that

a specific contaminant presents a public health risk. Some of these “other” contaminants have already been regulated by the various states, which often react faster to widely expressed public concerns than the federal government. Examples include MTBE (an infamous gasoline additive), which was regulated by quite a few states before it finally made it on the last CCL, and 1,4-dioxane (solvent stabilizer), which is being increasingly detected in association with 1,1,1-TCA plumes, is regulated by some states, but it is not on the current CCL.

The main difficulty with the entire process of drinking water regulation is that human- ity now lives in a chemical universe created by our diverse activities. Literally hundreds of thousands of synthetic chemicals are being widely used in manufacturing and for

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various other purposes, with more than 1000 new ones introduced each year. In compar- ison, the USEPA’s CCL list has 37 SOCs under evaluation. It is simply not feasible, and it would certainly be cost prohibitive for any society, to engage in regulation of thousands of chemicals that may be present in water supplies at some minute concentrations, but of which is little known regarding their effects on the human health and the environment at such low concentrations. Instead, it is likely that the entire field of water resources management will be forced to take a holistic approach where drinking water regulations will be an integral part of much broader environmental regulations, including those of the carbon cycle. Simple examples are the questions of water treatment and the cost of it, including the required energy; is it better to “completely” treat the drinking water or the wastewater, no matter what, and how many chemical substances constitute the “com- plete” list. And finally, how do we estimate the true cost and benefits of our decisions with respect to the society and the environment?

Probably the only parts of the environment not yet widely influenced by the vast number of anthropogenic chemical substances are deep pristine confined groundwater systems. As such, they present an enormous treasure but are under increasing threat due to their natural connectivity with the shallow systems. As illustrated in Chap. 8, artificial aquifer recharge with surface water and treated wastewater is one of the most important aspects of water supply sustainability. Wastewater is being increasingly viewed as a true water resource and will certainly play a major role in water resources management in the very near future. In fact, in some countries the term wastewater is being replaced with the term “used water” to emphasize this trend.

With the advancement of analytical methods, which can detect concentrations at parts per trillion (ng/L) or lower, a large picture of the numerous chemicals present in water supplies has emerged only recently. Certain pharmaceutically active compounds (e.g., caffeine, aspirin, and nicotine), which have been known for over 20 years to occur in the environment, are now joined by a broad group of chemicals collectively referred to as PPCPs. It seems that this term has prevailed in practice as a synonym for emerging contaminants, although water- and wastewater-treatment industry prefers to use the term microconstituents.

PPCPs are a diverse group of chemicals comprising all human and veterinary drugs (available by prescription or over the counter, including the new genre of “biologics”), diagnostic agents (e.g., X-ray contrast media), “nutraceuticals” (bioactive food supple- ments such as huperzine A), and other consumer chemicals, such as fragrances (e.g., musks) and sun-screen agents (e.g., methylbenzylidene camphor); also included are “ex- cipients,” the so-called “inert” ingredients used in PPCP manufacturing and formulation (Daughton, 2007). Nanomaterials are an emerging subgroup of microcostituents consid- ered by many as the next industrial wonder. They are already present in cosmetics, sunscreens, wrinkle-free clothing, and food products. Because of their small size, nano- materials pose a challenge in terms of detection and treatment. Also because of their size they can enter all human organs including the brain, but very little is known of their fate and transport in the environment.

Only a subset of PPCPs, such as synthetic steroids, is known to be direct-acting en- docrine disruptors. However, little is known about the individual and combined effects of long-term exposure to most PPCPs and their degradation products at very low con- centrations.

The widespread use of PPCPs in the environment is a result of their unavoid- able, collective discharge by humans as well as animals. Some pharmaceuticals are not

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completely metabolized after consumption by humans or animals and are excreted in their original form, while others are transformed into different compounds (conjugates). Almost 20 percent of prescription drugs are flushed down the toilet unused, according to some estimates (Jeyanayagam, 2008). Domestic sewage is a major source of PPCPs, and CAFOs are a major source of antibiotics and possibly steroids (Daughton, 2007).

Free excreted drugs and derivatives can escape degradation in municipal sewage- treatment facilities where their removal efficiency is a function of the drug’s structure and treatment technology employed. Some conjugates can also be hydrolyzed back to the free parent drug during the treatment process. After going through the wastewater-treatment plant, PPCPs and their degradation products are discharged to receiving surface waters and can find their way to groundwater, including by direct artificial aquifer recharge. The full extent, magnitude, and ramifications of their presence in the aquatic environ- ment are largely unknown (Daughton, 2007). Releases of PPCPs to the environment are likely to continue as the human population increases and ages; the pharmaceutical in- dustry formulates new prescription and nonprescription drugs and promotes their use, and more wastewater is generated, which enters the hydrologic cycle and may impact groundwater resources (Masters et al., 2004).