​​​​Atrazine is a herbicide, or weed killer, that has been used on corn and other crops for many years in Wisconsin. Today, we have restricted use of atrazine and prohibited it in some areas. 

This is because atrazine and its metabolites – substances formed as it breaks down in the environment – has been found to enter Wisconsin's groundwater from use on farm fields, spills or improper disposal. 

At low levels in drinking water, atrazine does not cause immediate sickness or health problems. However, if people drink water for many years that contains 3 parts per billion or more of atrazine or its metabolites, they may develop cardiovascular, reproductive, or other health problems. This 3 ppb level is called an "enforcement standard," which means that if we find it at that level, we may move to prohibit its use in the area where we find it. We do this by changing an administrative rule, ATCP 30, or through administrative order​. 

The U.S. Environmental Protection Agency classified atrazine as "not likely to be carcinogenic"; that is, it is unlikely to cause cancer.

Restrictions on Atrazine Use

Atrazine Prohibition Area Maps