Atrazine in Drinking Water

Atrazine is the second most widely used herbicide in the United States, applied primarily on corn, sorghum, and sugarcane crops, as well as on residential lawns and golf courses. Approximately 70-80 million pounds of atrazine are applied annually in the U.S., and because it is highly soluble in water and persists in the environment for months, it frequently makes its way into rivers, streams, and groundwater. It is one of the most commonly detected pesticides in U.S. drinking water, particularly in the Midwest corn belt region.

The health effects of atrazine exposure are a subject of active scientific debate and concern. The EPA's current standard focuses on cardiovascular and reproductive effects, but independent research has found that atrazine is a potent endocrine disruptor -- meaning it interferes with hormone systems even at very low concentrations. Studies have linked atrazine exposure to disrupted menstrual cycles, increased risk of preterm delivery, and possible links to breast and ovarian cancer. Research on amphibians has shown that atrazine can cause feminization of male frogs at concentrations as low as 0.1 parts per billion -- far below the current EPA standard. The European Union banned atrazine in 2004 due to its persistent groundwater contamination.

Atrazine levels in drinking water spike seasonally, typically peaking in late spring and early summer after application to crops coincides with spring rains. If you live in an agricultural area, particularly in the corn-growing states of the Midwest (Iowa, Illinois, Indiana, Ohio, Nebraska, Kansas), your water system may see seasonal atrazine spikes that temporarily exceed the MCL, even if annual averages are below the standard. The EPA allows compliance to be measured as a running annual average, which means short-term peaks may not trigger violations.