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Endocrine disrupting chemicals in the environment
Frequently Asked QuestionsConcerns about EDCs emerged more than a decade ago in Europe, where scientists found fish with altered reproductive systems in rivers that received large volumes of treated wastewater. Scientists found that very low levels of some compounds in the effluent were likely causing reproductive effects. New laboratory methods have recently enabled scientists to detect these compounds at very low levels in many of our waterways, so researchers can now begin studying this new endocrine disruption effect.
How do we know if a chemical is an endocrine disrupter?Only a few compounds are known EDCs. Because the science is young, many potential EDCs have not been tested yet. The U.S. Environmental Protection Agency is leading scientific research in the United States as directed by the 1996 update of the federal Safe Drinking Water Act and Food Protection Act. The European Union is coordinating very active efforts in many European countries. Universities and other government agencies around the world are also actively researching this issue. Are endocrine disruption effects different from other toxic effects?Yes, scientists are beginning to discover that these effects may be very complex and different from the familiar toxic effects researched in the past. The familiar, classic chemical toxicity occurs when high doses may cause immediate effects, and lesser doses cause long-term effects, but very low doses are assumed to be benign. With EDCs, very low concentrations appear to be causing effects. Also, EDCs can have very indirect effects on organs that regulate reproductive or growth processes. Some “turn on” processes while others ”turn off” processes—all at the same time. Thus, predicting the effects of individual chemicals or mixtures of chemicals acting together will take time. In addition, EDCs are not created equal. Different chemicals have different “potencies” or potential to cause effects similar to natural estrogens. Chemicals like synthetic estrogens in birth control pills have very potent effects while other chemicals like phthalates may be 1,000 times less “potent.” Phthalates may be more concentrated in the environment and pose a concern even though they are less potent. >> top of page What is being done?The first step is to identify which of the many chemicals cause endocrine disruption. The second step is to determine the exposure concentration at which these compounds may affect the endocrine system in aquatic organisms, wildlife and people. With knowledge about concentration and impacts, the next step is for federal and state agencies to regulate the chemicals identified as being of concern. While scientists have determined levels of some EDCs that may affect some organisms, methods of assessment have not been standardized. At this point, it is difficult to identify concentrations we think cause effects. How do EDCs get in the water?Chemicals such as pesticides run off lawns into stormwater systems that drain into local waterways. Residues from drugs and other consumer products we may use regularly—such as birth control pills, soaps, cosmetics and plastics—enter septic systems and sewer systems from toilets, sinks, showers and dishwashers. Domesticated animals and wildlife also contribute EDCs to the environment. Some can also enter water from the atmosphere. >> top of page Doesn’t wastewater treatment remove EDCs?Federal regulations require us to remove 85 percent of solid materials from wastewater before we discharge the treated effluent into natural water bodies. Regulations also require our wastewater discharges to meet state water-quality standards, but there are no waterquality standards for some of these compounds. While standards are available for some compounds (PCBs, some pesticides), the standards were not based on impacts to the endocrine system. King County’s treatment plants in Seattle and Renton use a two-stage process called conventional secondary treatment that typically removes 95 percent of the solids; however, this process does not remove all contaminants or EDCs. Membrane bioreactor technologies, an advanced wastewater treatment process, are proving capable of removing a larger amount of solid materials from wastewater than conventional secondary treatment. For example, the membrane bioreactor technology to be used at the Brightwater and Carnation wastewater treatment plants will produce cleaner water by removing more solids and smaller particles than current technology. Even these advanced technologies are not expected to remove all contaminants or EDCs. Higher levels of removal are possible but very expensive. Preventing EDCs from entering the wastewater stream is the easiest and least expensive way to protect people and the environment. Please refer to the list of resources and programs at the end of this fact sheet on how to control chemicals at the source. How do EDCs affect fish and people?Current research suggests that exposure of fish to some EDCs can mimic estrogen and lead to changes in sex ratios (changed percentage of male and female in the wild), “feminization” of male fish (showing some female characteristics), production of vitellogenin (the protein precursor to egg production in female fish) by male fish, and other changes that may affect reproduction or overall health. Other EDCs can mimic androgen (a male hormone) and have different or opposite effects from the estrogen mimicker. Continuing research by the National Marine Fisheries Service of the National Oceanic and Atmospheric Administration Fisheries (NOAA Fisheries) and other agencies throughout the world will help us better understand the potential effects of these chemicals on fish and other aquatic organisms. NOAA Fisheries and the Washington Department of Fish and Wildlife scientists have seen evidence of effects on the reproductive cycle of English sole in Puget Sound. They hypothesize that these effects are due to exposure to EDCs. To determine the degree of adverse effect on an organism, scientists must find a relationship between the exposure to an EDC and an adverse effect. While experiments can measure the effects on individuals, it is difficult to measure the extent of effects on populations. Regarding human health issues, the Water Environment Research Foundation has tried to summarize current information on EDCs. The report shows that no studies have linked low concentrations of EDCs in our environment to adverse health effects in people. While effects might be found in the future, they have not been seen so far in several large studies. >> top of page
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Department of Natural Resources and Parks Updated: Jan. 27, 2006
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King County | Natural Resources & Parks | Wastewater Treatment Division Links to external sites do not constitute endorsements by King County. |
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