EPA seeks to lower risks of malathion

The US Environmental Protection Agency is moving ahead with a plan to allow the organophosphate pesticide malathion to remain on the market with new requirements intended to reduce spray drift. In a proposed decision released July 17, the agency says new mandatory language on pesticide labels will help mitigate ecological risks. Environmental groups say the measures do not go far enough to protect children from neurodevelopmental effects.

The EPA revised its human health and ecological risk assessments for malathion earlier this year, concluding that it did not find potential risks to human health, including risks to pregnant women and children. But the agency did find ecological risks. The EPA says it evaluated multiple sources of data, including human epidemiological studies, toxicity studies in laboratory animals, and in vitro assays that use human nervous system cells.

Developmental neurotoxicity associated with malathion exposure occurs at levels 6 to 4,800 times higher than those that lead to acute neurotoxicity, the EPA says in an update. The label protects people from acute neurotoxicity, which occurs when the enzyme acetylcholinesterase is inhibited, so it also protects them from neurodevelopmental effects, the agency contends.

Earthjustice, an environmental law group, argues that the EPA relied too heavily on results from in vitro assays. Such tests can predict eye or skin irritation, but they are “ill-equipped to evaluate whether organophosphates will cause learning disabilities or behavioral disorders,” the group says in a press release.

“By improperly downplaying the known risks of organophosphate exposure, EPA is squandering a critical chance to safeguard the least-protected, especially farmworker communities,” Earthjustice attorney Patti Goldman says in a statement.

The EPA is accepting comments on the proposal and its revised malathion risk assessments until Sept. 16.