Weed Killer in the Crosshairs: Concerns prompt reexamination of atrazine's safety
By Janet Raloff   Science News

Each year, American farmers and turf managers apply some 34 million kilograms of atrazine to quash broad-leaved and grassy weeds. Most treatments go to protect corn, sorghum, sugarcane and cotton, though golf courses sometimes tap the weed killer to maintain immaculate fairways and putting greens.

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Atrazine, an organic compound belonging to the triazine family of herbicides, stops pre- and post-emergent weeds by inhibiting electron transport, ultimately blocking photosynthesis. The EPA reexamined data on the herbicide's putative toxicity four years ago as part of a systematic review of the safety of older pesticides -- those initially registered for use before 1984. Atrazine was reregistered -- meaning it could continue to be sold -- after the EPA concluded that its regulated use could continue without posing undue risks to health and the environment. The chemical is banned by the European Union and, ironically, in Switzerland, where atrazine's leading manufacturer, Syngenta, is headquartered.

In a surprising turnabout, the EPA instructed its Scientific Advisory Panel on pesticides, a group of outside experts, to reevaluate the weed killer's safety through three meetings this year, the first of which took place earlier this month. The panel will review human data and any studies, including animal or test-tube assays, that might suggest risks to people.

EPA admits this new review was prompted by a flurry of recent news stories and critical reports by advocacy groups, which continue to show that large numbers of people are being exposed to atrazine through drinking water (SN: 11/3/01, p. 285) and which offer new data suggesting health concerns.

Among these new criticisms was a report in August by the Natural Resources Defense Council: "Poisoning the Well: How the EPA is ignoring atrazine contamination in surface and drinking water in the central United States." Its analysis of data that the EPA collected -- but didn't publicly release --shows that traces of atrazine frequently pollute not only rivers but also water exiting the tap, oftentimes at concentrations exceeding EPA's 3-parts-per-billion limit for drinking water.

A welcome development in the USA is the revisiting of poor decisions made by EPA and others in an environment of political pressure under G. W. Bush.

"It is not necessary to have hope in order to persevere."