According to a study which lasted from 1992 to 2001 most of the US 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.

The cumulative effects of continued use of these waters for drinking and food remain uncertain.

“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.