Water Contaminant Atrazine Likely Carcinogenic

Dec. 28, 2000

The U.S. Environmental Protection Agency has found that atrazine, the most common weed killer on the nation’s farms and a common tap water contaminant in the Midwest, is more toxic than previously thought to be.

The EPA has stepped up its carcinogenic assessment of atrazine: Instead of being a "possible" carcinogen, it is "likely" to cause cancer. When EPA conducted its first in-depth study at the potential harm atrazine has to children, it found the chemical to cause harmful effects to the fetus, infant and child reaching puberty. Short term and even a single-day's exposure to atrazine may cause a range of reproductive effects and developmental defects, including miscarriage, and delayed vaginal opening and penis development during puberty.

Atrazine is widely used by corn and soybean farmers. Almost 20,000 metric tons of the pesticide are spread over crop fields in states along the Mississippi River every spring. After spring rain or irrigation, atrazine runs from those fields into rivers, lakes and streams that also serve as the drinking water sources.

The EPA currently enforces a standard for atrazine in drinking water of 3 parts per billion. The U.S. Geologic Survey has detected atrazine levels above the federal standard in the Mississippi, Missouri and Ohio rivers.

EPA says it may need to adopt a higher drinking water standard in regards to atrazine. Instead of taking an annual average count, the agency may base requirements on short term, even single-day, exposures. Utilities could be required to test as often as every day during the peak contamination period--more than 100 times per year. Atrazine contaminates the tap water of more than 10 million people in the Midwest and causes more health standard violations in tap water than any other EPA regulated chemical pollutant.

Although public drinking water providers employ special water treatment methods to combat atrazine contamination, the pesticide is very water soluble and does not degrade quickly, making it at times impervious to treatment efforts. Nevertheless, water utilities generally double their treatment costs in trying to get atrazine out of the water supply, which in turn raises consumer water rates. Water utilities now spend at least $30 million per year testing and treating tapwater for the chemical.

"Atrazine is dangerous to humans and difficult to clean up," said Jack Hoffbuhr, executive direction of the American Water Works Association. "EPA must continue monitoring for atrazine pollution as long as drinking water utilities--and consumers--must pay to clean it up."

(Source: American Water Works Association)