By Friday, President Donald Trump's Environmental Protection Agency will have to make a momentous decision: whether to protect kids from a widely used pesticide that's known to harm their brains—or protect the interests of the chemical's maker, Dow AgroSciences.
The pesticide in question, chlorpyrifos, is a nasty piece of work. It's an organophosphate, a class of bug killers that work by "interrupting the electrochemical processes that nerves use to communicate with muscles and other nerves," as the Pesticide Encyclopedia puts it. Chlorpyrifos is also an endocrine disrupter, meaning it can cause "adverse developmental, reproductive, neurological, and immune effects," according to the National Institutes of Health.
Major studies from the Mount Sinai School of Medicine, the University of California-Davis, and Columbia University have found strong evidence that low doses of chlorpyrifos inhibits kids' brain development, including when exposure occurs in the womb, with effects ranging from lower IQ to higher rates of autism. Several studies—examples here, here, and here—have found it in the urine of kids who live near treated fields. In 2000, the EPA banned most home uses of the chemical, citing risks to children.
Stephanie Engel, an epidemiologist at the University of North Carolina and a co-author of the Mount Sinai paper, says the evidence that chlorpyrifos exposure causes harm is "compelling"—and is "much stronger" even than the case against BPA (bisphenol A), the controversial plastic additive. She says babies and fetuses are particularly susceptible to damage from chlorpyrifos because they metabolize toxic chemicals more slowly than adults do. And "many adults" are susceptible, too, because they lack a gene that allows for metabolizing the chemical efficiently, Engel adds.