Atrazine reaches harmful levels in one quarter of US river miles

A new analysis says atrazine, a weed killer used on farms, reaches levels that can harm river life in about one quarter of river and stream miles in the lower 48 states. That is about 860,000 miles. About 22% of drinking-water plants take some water from rivers the report found polluted.

The Center for Biological Diversity checked data from the Environmental Protection Agency (EPA). It counted waterways with more than 9.7 parts per billion of atrazine, a measure of how much chemical is in water. The EPA says this level can harm river life. The EPA’s drinking-water limit is 3 parts per billion. These plants get some water from polluted rivers, but the report does not give the amount of atrazine in tap water.

Farmers use atrazine on crops such as corn, soybeans, sugarcane and sorghum. They apply about 70 million pounds in the United States each year. Rain carries it from fields into streams. “Farmers use the compound in spring, it rains, and then it flushes into the streams,” said Dana Kolpin, a water scientist with the US Geological Survey.

Exposure to atrazine is linked to hormone problems, birth defects and low birth weight. The International Agency for Research on Cancer says atrazine probably can cause cancer, but the EPA rejected its review and cites earlier assessments that found no link. More than 60 countries have banned atrazine. The EPA is checking whether it can stay in use. These findings matter because atrazine can harm river life and some polluted rivers supply drinking water.