Endocrine disrupting chemicals in the environment  

New information is continually emerging about the natural and synthetic chemicals people and industries use every day and dispose of down their drains and toilets. Some chemicals of concern are classified as endocrine disrupting compounds, or EDCs.

Background

EDCs are natural or synthetic chemicals that interfere with or mimic the hormones responsible for growth and development of an organism.

Some EDCs are synthetic hormones (such as ethynylestradiol, found in birth control pills) and natural hormones (such as estrogen and testosterone). Some EDCs are found in commonly used products such as personal-care products like soaps and cosmetics (some contain nonylphenol compounds and parabens), industrial byproducts, plastics (phthalates) and pesticides.

When these products are used, disposed of, or excreted by people or animals, they typically end up in either stormwater or wastewater. While wastewater treatment processes can remove a significant amount of these compounds, small concentrations of some are discharged into surface waters.

Nationally and internationally, scientists are studying the potential effects of EDCs on aquatic life and wildlife. Several chemicals have been classified as EDCs, but many compounds have not yet been tested. Because this impact of EDCs is an issue of national and international scope, it is beyond the capability of a local agency or utility to solve alone. Studies will continue for many years before definitive answers are known and regulations adopted. King County understands public interest and concerns about this issue, so as we learn more, we will respond to recommendations and amend regulations as needed.

What King County is doing

Below is a summary of what we know and what we are doing now to deal with the issue of EDCs:

• Scientific analysis. King County scientists are tracking this issue carefully to keep up-to-date on new findings. King County's Environmental Laboratory is continuing to investigate new analytical methods for the complex testing of some of these chemicals. Sampling for 15 suspected EDCs in King County marine and fresh waters found the presence of some EDCs at low levels. They are natural estrogen (estradiol), synthetic estrogen (ethynylestradiol), plasticizers (phthalates), surfactants from soaps (nonylphenol), and epoxy compounds (Bisphenol A).
• Prevention and education for source control. Preventing EDCs from entering stormwater through a septic tank or sewer system is the easiest and least expensive way to protect people and the environment. To help reduce the problem, we offer resources and programs throughout King County on how to control chemicals at the source.
• Wastewater treatment. Conventional secondary wastewater treatment, designed to remove solids and biodegradable organic material from wastewater, removes from 50 to 90 percent of many compounds known to be or suspected of being EDCs. Both the West Point and South Treatment plants use this technology. King County is making efforts to use the advanced wastewater treatment technology where possible. We plan to install membrane bioreactors in the future Brightwater and Carnation treatment plants