If you’re alive, it’s safe to assume that you’ve come in contact with an insecticide called chlorpyrifos. You may or may not have suffered its effects, but until relatively recently, it was commonly used to solve those pesky insect problems most of us face at some point: mosquitoes, cockroaches, and other undesirable creepy crawlies.
A federal appeals court on Thursday ruled that the Environmental Protection Agency must ban the use of chlorpyrifos, according to The Associated Press, countering the EPA’s reversal in 2017 of the Obama administration’s 2015 efforts to get rid of the dangerous poison once and for all.
Dow Chemical Co. introduced chlorpyrifos to homes and farm fields in 1965, and it was a highly effective deterrent to just about all insects. Homeowners and farmers sprayed it; so did golf courses and municipalities. It was everywhere, and not just in the United States; the use of chlorpyrifos spread around the world.
Studies starting shortly after the insecticide was introduced indicated that close proximity to it was dangerous for people. Home use of chlorpyrifos was banned in the U.S. in 2000, when Dow withdrew it from the market voluntarily, though it is still found in insect baits. Golf courses still combat pests with it, and it’s still used by farmers on nearly 50 crops—many of which we consume, like oranges—and in cattle ear tags.
Chlorpyrifos is pretty nasty: It belongs to the same class of chemicals as sarin gas, a class called organophosphates. Chlorpyrifos is essentially a nerve agent, attacking chemical pathways and causing a breakdown in the ability of nerves to communicate. You can be exposed to it by inhaling it, eating it, or getting it on your skin.
The effects of the insecticide on animals and humans has been widely studied since the 1970s. According to the studies, chlorpyrifos affects living things to various degrees: It's very toxic to birds and insects, including bees, quite toxic to fish, and moderately toxic to humans. However, more recent studies of small children have found a link between chlorpyrifos and lower IQ and developmental problems, according to the Pesticide Action Network.
As for the next step for chlorpyrifos, the federal court ruled that the EPA ban its use within 60 days.