IssueWastewater treatment plants ar

Issue
Wastewater treatment plants are designed to eliminate pathogens, waste particles and nutrients like nitrogen. But other types of contaminants are more difficult to treat. Chemicals present in water in low concentrations may have an effect on the environment when released into waterways such as lakes and streams. Among these chemicals are potential endocrine disrupting chemicals (EDCs).
EDCs can end up in wastewater through a variety of routes. Wastewater can contain natural human hormones, hormones from pharmaceutical products like birth control pills, and potential EDCs present in detergents, soaps, plastics, food, and personal care products such as fragrances. EPA researchers have documented that chemical mixtures in some wastewater effluents (or outflows) can result in feminization of fish populations downstream of treatment plants. Additional ecological impacts of these effluents, and of effluents from other sources such as from concentrated animal feeding operations, are still being assessed.
However, it is clear that EDCs have the potential to disrupt fish populations. One 7 year study conducted by the Department of Fisheries and Oceans Canada and their EPA partners examined a lake in the Experimental Lake Area in Ontario, Canada, that was dosed for 3 years with a potent estrogen, 17-ethynylestradiol. The findings showed that chronic exposure of fathead minnow (Pimephales promelas) to low concentrations (ethynylestradiol EE2) led to defects in the reproductive development of females and males, and, ultimately, a near extinction of this species from the lake. The concentrations of the hormone used in this lake were similar to those measured in effluent-dominated waterways, suggesting that EDCs present in the environment can impact the sustainability of wild fish populations.