Research found raised Atrazine levels in 94 of 136 water systems tested at the source in Indiana, Ohio, Iowa, Kentucky, Minnesota and Nebraska. Data was collected by the EPA through two monitoring programs implemented from 2003 to 2006, primarily in Midwest states.

Atrazine is a white, crystalline solid organic compound widely used as a herbicide for control of broadleaf and grassy weeds. Atrazine was estimated to be the most heavily used herbicide in the United States from 1987 to 1989, with its most extensive use for corn and soybeans in Illinois, Indiana, Iowa, Kansas, Missouri, Nebraska, Ohio, Texas and Wisconsin. The EPA greatly restricted its use in 1993.

Ecological monitoring in 10 states shows that nearly all of 40 monitored watersheds had Atrazine concentrations at levels known to harm aquatic habitat and cause reproductive abnormalities in fish and amphibians.

Human exposure to Atrazine has been associated with multiple forms of cancer, including lung, bladder, non-Hodgkin lymphoma, leukemia, multiple myeloma, ovarian and colon cancer.

The EPA’s regulation for Atrazine became effective in 1992. Between 1993 and 1995, EPA required water suppliers to collect water samples every three months for one year and analyze them to find out if Atrazine was present above one part per billion. If it was present above this level the system must continue to monitor this contaminant.

If contaminant levels are found to be consistently above the allowed level, water suppliers must take steps to reduce the amount of Atrazine so that it is consistently below that level by removing it with granular activated charcoal.