Pesticides found in most U.S. rivers, streams

US - Most of the nation's rivers and streams - and the fish in them - are contaminated with pesticides linked to cancer, birth defects and neurological disorders, but not at levels that can harm humans.

Pesticides were found in almost all U.S. rivers and streams between 1992 and 2001, says a study released Friday by the U.S. Geological Survey, although most drinking water supplies haven't been affected.

"While the use of pesticides has resulted in a wide range of benefits to control weeds, insects and other pests, including increased food production and reduction of insect-borne disease, their use also raises questions about possible effects on the environment, including water quality," said Robert Hirsch, the USGS associate director for water.

Pesticides were seldom found at concentrations likely to affect people, and they were less common in groundwater. But they were found in most fish.

Most frequently detected in agricultural streams were three herbicides used mainly on farms: atrazine, metolachlor and cyanazine. Just last week, the Environmental Protection Agency settled a 2003 lawsuit brought by the Natural Resources Defense Council, forcing the government to assess whether atrazine threatens the survival of endangered Chesapeake Bay sea turtles, endangered Texas salamanders and 16 other aquatic species.

Three other herbicides used commonly in cities — simazine, prometon and tebuthiuron — showed up more often in urban streams.

The USGS looked for 100 pesticides, and found 40 of them had a widespread presence in streams and sediment in both urban and agricultural areas, at concentrations that could affect aquatic life or fish-eating wildlife. The pesticides showed up more than 90 percent of the time in the fish tissue found in agricultural, urban and mixed land-use areas.

Source: CTV
calendar icon 10 March 2006
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