Earth and Sky科普英語：Estrogen Mimics 雌性激素

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It may not surprise you that pollution from chemical plants and farms can harm fish. But there's growing evidence that we're all hurting fish and frogs by what we flush down the drain. Discover estrogen mimics -- today on Earth and Sky.

DB: This is Earth and Sky. In recent years, scientists have found dozens of human made chemicals in streams and rivers that may disrupt the reproductive systems of animals.

JB: Some of these chemicals act like the natural hormone estrogen. So-called "estrogen mimics" are found in many compounds that have become common in modern life -- pharmaceuticals, pesticides and industrial or residential waste.

Some enter the water in effluent from wastewater treatment plants. In some animals such as fish, frogs and birds -- and at certain levels -- these chemicals can cause males to become more like females, sperm counts to shrink, or eggs to become thinner. Some scientists also worry about possible effects on humans.

DB: A research team is studying the effects of estrogen mimics on fish in New York's Jamaica Bay . Effluent from a nearby sewage treatment plant contains these chemicals. Ann McElroy, Martin Schreibman and others are growing winter flounder in water with chemicals in varying amounts. They'll measure how the chemicals affect the fishes' hormone levels, size of certain organs and ability to reproduce. They'll compare fish in the lab to fish in Jamaica Bay and in natural sites that are relatively free from estrogen mimics.

JB: For more -- come to today's show at earthsky.org. Special thanks to New York Sea Grant -- bringing science to New York's marine and Great Lakes shores for over 30 years. We're Block and Byrd for Earth and Sky.