Chlorpyrifos has been historically one of the most widely used pesticides in the US. The risk of the acute affects of chlorpyrifos are acceptable if the product is used according to directions. However, there is increasing evidence that chlorpyrifos use may result in unacceptable risks from chronic exposures. For these reasons, the US-EPA is proposing an end to the use of chlorpyrifos on agricultural crops by early 2017 by revoking the tolerances (allowable pesticide residues) on food crops. If the amount of chlorpyrifos residue allowed on crops at the time of harvest is zero, then growers cannot use chlorpyrifos on food crops and legally market their crops in the US. Chlorpyrifos will no longer be labeled or formulated for food crops.
Chlorpyrifos, like all other cholinesterase inhibitor insecticides, has been under increasing scrutiny. All indoor use of cholinesterase inhibitor insecticides including chlorpyrifos were banned in 2002 out of concern for exposure to pesticide residues, especially among young children with developing nervous systems. Unlike many other insecticide classes, organophosphorus insecticides such as chlorpyrifos can have irreversible effects on enzymes with affects accumulating with serial exposures.
Chlorpyrifos has been detected at unacceptable levels in drinking water in some locations. Exposure via drinking water may exceed acceptable levels for some people. The US-EPA is also investigating chlorpyrifos effects on endangered species. In the past, banning OP insecticides was not possible for lack of alternative controls for crop pests. Today, GMO crops and newer insecticides that pose fewer risks to human health are effective replacements. Look for the chlorpyrifos era to end next year.