Little Green Molecules; March 2006; Scientific American Magazine; by Terrence J. Collins and Chip Walter; 8 Page(s)

The fish that live in the Anacostia River, which flows through the heart of Washington, D.C., are not enjoying its waters very much. The Anacostia is contaminated with the molecular remnants of dyes, plastics, asphalt and pesticides. Recent tests have shown that up to 68 percent of the river's brown bullhead catfish suffer from liver cancer. Wildlife officials recommend that anyone who catches the river's fish toss them back uneaten, and swimming has been banned.

The Anacostia is just one of dozens of severely polluted rivers in the U.S. The textile industry alone discharges 53 billion gallons of wastewater--loaded with reactive dyes and other hazardous chemicals--into America's rivers and streams every year. New classes of pollutants are turning up in the nation's drinking water: traces of drugs, pesticides, cosmetics and even birth-control hormones. The amounts are often infinitesimal, measured in parts per billion or trillion (a part per billion is roughly equivalent to one grain of salt dissolved in a swimming pool), but scientists suspect that even tiny quantities of some pollutants can disrupt the developmental biochemistry that determines human behavior, intelligence, immunity and reproduction.