WASHINGTON — No fish can escape mercury pollution. That’s the take-home message from a federal study of mercury contamination released Wednesday that tested fish from nearly 300 streams across the country. The toxic substance was found in every fish sampled, a finding that underscores how widespread mercury pollution has become.
But while all fish had traces of contamination, only about a quarter had mercury levels exceeding what the Environmental Protection Agency says is safe for people eating average amounts of fish.
The study by the U.S. Geological Survey is the most comprehensive look to date at mercury in the nation’s streams. From 1998 to 2005, scientists collected and tested more than a thousand fish, including bass, trout and catfish.
“This science sends a clear message that our country must continue to confront pollution, restore our nation’s waterways, and protect the public from potential health dangers,” Interior Secretary Ken Salazar said.
Mercury consumed by eating fish can damage the nervous system and cause learning disabilities in developing fetuses and young children. The main source of mercury to most of the streams tested, according to the researchers, is emissions from coal-fired power plants that rains down into waterways, where natural processes convert it into methylmercury — a form that allows the toxin to wind its way up the food chain into fish.
Mercury also was found in high concentrations in western streams that drain areas mined for mercury and gold.
