Atrazine is an herbicide, a white crystalline powder that when sprayed over cornfields very quickly displays its remarkable ability to kill the grasses and broadleaf weeds that make a corn farmer's life miserable, while leaving the corn itself alone.
Atrazine has been showing up in the USA in supermarket corn, and in beef and milk. (Atrazine-treated corn is routinely fed to cattle.) And it has become one of the leading contaminants of drinking water. The chemical was found in 990 of 1,604 water samples drawn from streams, rivers, reservoirs and aquifers in the Midwest from 1989 to 1994. According to a 1997 estimate by the US Environmental Protection Agency, some corn farmers faced a 1 in 863 lifetime risk of developing cancer from atrazine. Non-farmers in the Midwest faced a 1 in 20,747 risk, and a 1 in 13,850 risk if they used atrazine on their lawns. The EPA generally takes regulatory action when a chemical poses a lifetime cancer risk higher than one in a million.