High Weedkiller Levels Found in River Checks

By Juliet Eilperin
Washington Post Staff Writer
Sunday, December 9, 2007

Atrazine, the second most widely used weedkiller in the country, is showing up in some streams and rivers at levels high enough to potentially harm amphibians, fish and aquatic ecosystems, according to the findings of an extensive Environmental Protection Agency database that has not been made public.

The analysis -- conducted by the chemical's manufacturer, Syngenta Crop Protection -- suggests that atrazine has entered streams and rivers in the Midwest at a rate that could harm those ecosystems, several scientific experts said. In two Missouri watersheds, the level of atrazine spiked to reach a "level of concern" in both 2004 and 2005, according to the EPA, and an Indiana watershed exceeded the threshold in 2005.

Much of the data on atrazine levels has remained private because Syngenta's survey of 40 U.S. watersheds was done in connection with the EPA's 2006 decision to renew its approval of the pesticide. The Washington Post obtained the documents from the Natural Resources News Service, a District-based nonprofit group focused on environmental issues.

Atrazine has been linked to sexual abnormalities in frogs and fish in several scientific studies, but the EPA ruled in September that the evidence was not sufficiently compelling to restrict use of the pesticide. EPA spokeswoman Jennifer Wood said the agency "has concluded that atrazine does not adversely affect gonadal development in frogs, based on a thorough review of 19 laboratory and field studies, including studies submitted by [Syngenta] and others in the public literature."

The pesticide is popular among corn and sorghum farmers despite the controversy because it is inexpensive and blocks photosynthesis, thus killing plants to which it is applied.

"It works and it's inexpensive, and that's what farmers love," said Tim Pastoor, head of toxicology at Syngenta. "It's magic for them. It's like the aspirin of crop protection."

EPA officials and independent experts spent last week in meetings in Arlington, debating the "ecological significance" of atrazine water contamination, according to agency documents. The results of the deliberations -- the monitoring data was plugged into computer models to estimate the effects on ecosystems -- will be published in several weeks and will help determine how EPA officials regulate the pesticide in the future.

The federal government first approved atrazine in the 1950s, but it came under increased scrutiny in the late 1990s after Tyrone B. Hayes, a professor of integrative biology at the University of California at Berkeley, did a series of studies -- first for chemical companies and then on his own -- that indicated that tiny amounts of the pesticide de-masculinized tadpoles of African clawed frogs. The European Union declared it a harmful "endocrine disrupter" and banned it as of 2005, but the EPA decided to allow its continued use after determining that the agency lacked a standard test for measuring the hormone-disrupting effects of chemicals.

Instead, EPA officials and company representatives agreed on a plan to monitor atrazine levels in "40 of the most vulnerable watersheds in the country," said Jim Jones, deputy assistant administrator for the EPA's Office of Prevention, Pesticides, and Toxic Substances.

Syngenta has collected more than 10,000 samples since 2004, Pastoor said, taking readings at least every four days at each site.

Jones said there are limits on what details of the Syngenta survey can be released to the public -- the company claims some of the data is proprietary information, and anyone who requests the information must pledge not to share it with competing pesticide companies -- but the monitoring system is protecting the public's health.

Nancy Golden, a biologist and toxicologist at the U.S. Fish and Wildlife Service who studies how chemicals affect aquatic creatures, said fish exposed to as little as 0.5 parts per billion of atrazine in the lab demonstrate behavioral problems. At higher levels, they experience stunted growth. The levels of atrazine in 2004 in the two Missouri sites were more than 100 times the 0.5 parts per billion concentration, the Syngenta data show.

CONTINUED     1        >

© 2007 The Washington Post Company