The Decade-Long Legal Battle over Chlorpyrifos and the EPA’s Next Steps

November 6, 2019 by Alka Paturi

Chlorpyrifos has been the subject of much regulation in recent years. With the European Union on track to ban large-scale agricultural use of chlorpyrifos, where does the EPA stand on this hazardous chemical?

Chlorpyrifos is a pesticide used in over 100 countries.[1] Mainly applied to cotton, corn, almonds, and fruit trees, chlorpyrifos was originally used for both residential and agricultural purposes.[2] However, following widespread concern in the scientific and regulatory communities about potential chlorpyrifos exposures to humans through residential use, Dow AgroSciences (in agreement with the EPA) began phasing out in-home uses of chlorpyrifos in 2000.[3]


The status of chlorpyrifos has been the subject of a legal battle that has spanned over a decade. In September 2007 the Pesticide Action Network and Natural Resources Defense Council petitioned the EPA to ban chlorpyrifos citing the risks posed to humans and animals.[4] In 2018, the Court of Appeals for the Ninth Circuit ordered the EPA to revoke all tolerances for the insecticide, deny the petition, or issue a proposed or final tolerance revocation no later than October 31, 2015.[5] The EPA then proposed to revoke all chlorpyrifos tolerances.[6] This decision was immediately appealed by Dow AgroSciences. The EPA reversed its decision in March 2017.[7]


On the other side of the Atlantic, the European Union is on track to disallow chlorpyrifos use come January 2020.[8] The European Food Safety Authority provides scientific advice and information regarding food safety so that EU member states, European Parliament, and European Commission may make decisions regarding the health of their citizenry. On the advice of the EFSA, a peer-review panel is evaluating whether applications for chlorpyrifos renewal should be approved.


The World Health Organization classifies chlorpyrifos as moderately hazardous.[9] Increasingly, epidemiological studies show that prenatal exposure to organophosphate pesticides, such as chlorpyrifos, may be associated with IQ reductions in children.[10] The pesticide is also toxic to bees when they directly come into contact with pesticide residue on flowering plants.[11]


Chlorpyrifos has many adverse effects on wildlife and human beings, even when being used for solely agricultural purposes. The EPA’s move under the Trump administration to continue the use of chlorpyrifos is likely to cause widespread harm, particularly to children in agricultural communities, where the pesticide can reach them via contaminated food and unsafe drinking water.[12] The majority of farmworkers in these communities are foreign-born with low levels of English proficiency and education.[13] There is therefore little awareness among those most vulnerable to the ill effects of pesticides like these.


Many Democrat Senators on the Senate Appropriations Subcommittee overseeing the Environmental Protection Agency’s (EPA) budget have now introduced a bill, the Protect Children, Farmers and Farmworkers from Nerve Agent Pesticides Act of 2019, to ban all uses of the pesticide on food crops, citing its toxicity.[14] The bill is set to “effectively outlaw” chlorpyrifos given the clear science linking this ubiquitous chemical with neurodevelopmental problems and other health effects.


Given chlorpyrifos’ proven toxicity, the disproportionate harm it will cause to members of low-income agricultural communities, and the international community’s widespread condemnation of it, the EPA should prioritize public health concerns and ban chlorpyrifos from large-scale agricultural use.

[1] Chlorpyrifos: Target Pests, Dow AgroSciences, (last visited Nov. 4, 2019).

[2] Id.

[3] Chlorpyrifos and Responsible Use, Dow AgroSciences, (last visited Oct. 30, 2019).

[4] Chlorpyrifos: The toxic pesticide harming our children and the environment, Earthjustice, (last visited Oct. 30, 2019).

[5] In re Pesticide Action Network N. Am. v. EPA, 798 F.3d 809, 811 (9th Cir. 2015).

[6] EPA to ban dangerous pesticide chlorpyrifos, Earthjustice (Oct. 30, 2015),

[7] Britt E. Erickson, No safe exposure to chlorpyrifos, EU regulators say, Chem. & Eng’g News (Aug. 5, 2019),

[8] Id.

[9] The WHO Recommended Classification of Pesticides by Hazard, World Health Org., (last visited Oct. 30, 2019).

[10] Brett Israel, Common Insecticide May Harm Boys’ Brains More Than Girls’, Sci. Am. (Aug. 21, 2012),

[11] Chlorpyrifos General Fact Sheet, Nat’l Pesticide Info. Ctr., (last visited Oct. 30, 2019).

[12] Press Release, Tom Udall, Udall, Senators Introduce Bill to Ban Toxic Pesticide Chlorpyrifos (Mar. 28, 2019)

[13] Israel, supra note 9.

[14] Udall, supra note 11.