Chlorpyrifos (Dow Chemical Co.), a broad-spectrum, chlorinated organophosphates insecticide, was introduced in 1965 and goes by various trade names: Dursban, Lorsban, Bolton Insecticide, Nufos, Cobalt, Hatchet and Warhawk. 
It is used to control mosquitoes, ticks and mites. It is widely sprayed on crops and turf.

The insecticide was banned for most home use in 2001. The EPA assessment indicated that all residential post-application exposures were of concern, and the Columbia Center for Children's Environmental Health (CCCEH) study on pregnant women reported an association between fetal cord blood levels of chlorpyrifos and neurodevelopmental outcomes.

In November 2016, the EPA revised its human health risk assessment and drinking water exposure assessment for chlorpyrifos https://tinyurl.com/y9oagjc5 (41-page document). Among it's findings, the EPA assessed residential bystander exposure from field volatilization of applied chlorpyrifos. "Of the 11 acute ambient air concentrations assessed, six resulted in risk estimates that are of concern."

Attorneys general from seven states"?uNew York, California, Maine, Maryland, Massachusetts, Washington and Vermont"?uhave filed challenges to Pruitt's decision to allow the ongoing use of chlorpyrifos. The states assert the EPA wrongly approved the continued use of the pesticide on fruits and vegetables without first assessing its safety as required under the U.S. Food, Drug, and Cosmetic Act.