What are Emerging Contaminants?
New analytical capabilities have allowed scientists to identify chemicals in the environment in extremely small concentrations. Emerging contaminants (ECs) are those chemicals that recently have been shown to occur widely in water resources and identified as being a potential environmental or public health risk, and yet adequate data do not exist to determine their risk (Drewes and Shore 2001, Younos, 2005). ECs are used every day in our homes, on our farms, or by businesses and industry and include detergents, fragrances, prescription and nonprescription drugs, disinfectants, and pesticides. Some ECs have been shown to be common in water resources around the world, across the Nation, and in Colorado (Ternes, 1998; Kolpin et al., 2002; Sprague and Battaglin, 2005). The occurrence of some emerging contaminants correlates with ecological effects and sexual abnormalities in fish, although a cause-and-effect relation has not been established.
Results from recent research indicate that some of these compounds can act as endocrine disrupting compounds and are present in municipal wastewater effluent at concentrations capable of inducing feminization in fish (Jobling and others, 1998; Kavanagh and others, 2004). The feminization has been linked to exposure to compounds that mimic estrogen activity. However, it has also been determined that thousands of compounds have the potential to interact with components of the endocrine system, altering the natural action of the hormone (Drewes and others, 2006).
Some ECs have been shown to be common in water resources around the world, across the Nation, and in Colorado (Ternes, 1998; Drewes and Shore, 2001; Kolpin and others, 2002; Yang and Carlson, 2003; Lee and others, 2004; Sprague and Battaglin, 2005; Barber and others, 2006a; Loraine and Pettigrove, 2006; Barnes et al, 2008; Focazio et al, 2008). ECs have also been shown to occur in soilirrigated with reclaimed water (Kinney and others, 2006), accumulate in fish from wastewater treatment wetlands (Barber and others, 2006b), and to disrupt cellular development and hormonal function in sheep reared on sewage-sludge treated pasture (Catriona et al, 2005). Complex mixtures of ECs at environmentally relevant concentrations were reported to inhibit the growth of human embryonic cells (Pomati et al, 2006) and to produce significant effects at the molecular level even at levels below no-observed-effect-concentrations (Silva et al, 2002). The occurrence of some emerging contaminants correlates with ecological effects and sexual abnormalities in fish (Jobling and others, 1998; Barber and others, 2006b; Vajda et al., 2008). There is also evidence that some ECs are persistent in the environment and survive through conventional water treatment processes representing a potential concern to public drinking water supplies utilizing water resources that contain ECs (Drewes and others, 2003; Westerhoff and others, 2005). At an August 2005 workshop sponsored by the U.S. Environmental Protection Agency (EPA) on pharmaceutical residues and personal care products in the environment, EPA officials announced the agency may include a significant number of pharmaceuticals and personal care products on the third candidate contaminant list (CCL3) published pursuant to the Safe Drinking Water Act. The draft CCL3 list is expected to be published this year and finalized in 2008 (Mannina, 2006). The proactive and interdisciplinary approach CREEC has proposed to address these issues may serve as a prime example for other communities nationwide since there is simply not a single solution to the problem and the EC issue requires approaches tailored to account for regional specifics. The current extent of knowledge for most ECs is that there is not enough information available to make an estimate of the ecotoxicological risk of ECs to the environment (Global Water Research Coalition, 2004).
Why Study Emerging Contaminants in the Rocky Mountain Region?
The increasing need to conserve and reuse water can lead to increases in the number and concentration of many ECs and underscores the need for more scientific assessment to better understand the sources of ECs, the effectiveness of removal by wastewater- and drinking-water-treatment processes, the transport and environmental fate of these compounds, and their potential for physiological effects on humans and wildlife. The Rocky Mountain region is an ideal laboratory for studies of the source, fate, and effects of ECs. All of the components for a risk assessment are here—an identified problem (aquatic biological abnormalities), potential causes for the problem, a gradient of exposure, and an established network of scientists, decision makers, and key stakeholders willing to address the problem.
Many streams originate high in the Rocky Mountains and, in a relatively short distance, flow through pristine forests, high-use recreational areas, rapidly growing urban areas, and intensively farmed agricultural lands. As these streams leave the mountains, the water is used by agriculture and growing urban populations, and streamflow becomes dependent on treated wastewater, non-point discharges, and return flows from agricultural land. Due to the semiarid climate of the region, most streamflows are relatively limited so that dilution of ECs is minimal. Pressure on this relatively limited resource results in frequent reuse of water for urban, agricultural, and drinking water. Each reuse of water can result in additions of manmade compounds, including ECs, to the resource. As a result, Rocky Mountain region streams provide a unique gradient of water-quality, land-use, and demographic conditions where the source, fate, transport, and effects of ECs can be easily observed.