Regulatory Tracker

Chlorpyrifos Pesticide Use

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Why it Matters

Chlorpyrifos is a highly toxic organophosphate pesticide used since 1965 on crops like corn, soybeans, wheat, and a variety of fruits and vegetables, as well as cotton – and on golf courses. It is one of the most widely used pesticides in the United States. Over time, the Environmental Protection Agency (EPA) has narrowed the acceptable uses for this pesticide, as research revealed serious health and ecological risks. For instance, in 2000, EPA banned the use of chlorpyrifos for household use (except for child-resistant ant and roach traps) and on tomatoes.


EPA regulates pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA).

1996 Congress strengthens both laws in the Food Quality Protection Act, which passes both houses unanimously. The Food Quality Protection Act directs EPA to use a 10-fold safety buffer in its risk assessments (to capture the risks of pesticide exposure to children), and consider cumulative risk of pesticides. EPA reassesses risk for nearly 10,000 pesticides using these new factors. Over the course of this review, EPA revokes or modifies 4,000 assessments.

2006 EPA finalizes an assessment for chlorpyrifos, revising the tolerances (the amount of pesticide that can remain on food) for this pesticide.

Sep. 12, 2007 The Natural Resources Defense Council (NRDC) and Pesticide Action Network North America (PANNA) petition EPA to “revoke all tolerances and cancel all registrations for the pesticide chlorpyrifos.” The petition describes new research, including studies suggesting links between fetal exposure to the pesticide and developmental delays.

July 22, 2010 NRDC and PANNA file a lawsuit in federal court, challenging EPA’s failure to respond. NRDC v. EPA, No. (S.D. NY) The case is stayed when EPA agrees to issue a human health risk assessment and respond to the petition by November 2011.

July 25, 2012 and July 15, 2014 EPA provides interim responses, suggesting it might deny most but not all of the claims in the petition. EPA also indicates it will expedite a review of chlorpyrifos. However, the agency does not adhere to the schedules negotiated with plaintiffs, and in April 2012 and September 2014, PANNA files writs of mandamus with the Ninth Circuit (asking the court to force EPA to fulfill their regulatory obligations).

Aug. 10, 2015 The Ninth Circuit orders EPA to fully respond to the environmental groups’ petition by Oct. 31, 2015. A week after the deadline, EPA publishes a proposal to revoke all tolerances for chlorpyrifos (for food application). The Ninth Circuit orders EPA to finalize this rule by March 31, 2017.

April 2016 The FIFRA Scientific Advisory Panel (SAP) meets and discusses research on chlorpyrifos. The SAP concludes that the point of departure (the dosage of the pesticide at which there aren’t observable effects) in EPA’s risk assessment is not protective enough.

Nov. 17, 2016 EPA issues a brief Notice of Data Availability and suggests it will change the point of departure based on SAP input.

Trump Era

April 5, 2017  EPA formally denies the NRDC/PANNA petition and indicates it will not follow the negotiated schedule for rulemaking but will delay action on chlorpyrifos until the statutory deadline for reassessment on Oct. 1, 2022.

April 5, 2017 NRDC and PANNA file a motion with the Ninth Circuit to enforce the previous ruling requiring EPA to make a decision within 30 days on the proposed ban, arguing EPA presented no new evidence that the chemical was safe.

June 5, 2017 NRDC and other environmental groups, as well as seven states, file an administrative appeal with EPA “challenging the agency’s failure to finalize the ban on chlorpyrifos.”

July 18, 2017 The Ninth Circuit denies NRDC and PANNA’s appeal, saying “EPA had complied with the panel’s previous orders by issuing a ‘final response to the petition.’”

July 25, 2017 Senator Tom Udall (D-NM) introduces a bill to ban chlorpyrifos in the US. Senate Bill 1624, the “Protect Children, Farmers, and Farmworkers from Nerve Agent Pesticides Act of 2017,” is in the Committee on Agriculture, Nutrition, and Forestry.

Dec. 29, 2017 NMFS issues a Biological Opinion under the Endangered Species Act on chlorpyrifos and two other pesticides, stating that “EPA’s proposed registration of pesticides containing chlorpyrifos is likely to jeopardize the continued existence of 38 of the 77 listed species, and adversely modify 37 of the 50 designated critical habitats.” Affected species include endangered salmon and the orca that eat them. The opinion was made public by Earthjustice on Jan. 9, 2018, and could force EPA to reconsider the permitted uses of chlorpyrifos. NMFS recommended “Reasonable and Prudent Alternatives” that EPA must comply with and “are necessary and appropriate to minimize the impacts of incidental take on threatened and endangered species.” These include limiting where and how the pesticide is used.

Jan. 31, 2018 EPA Administrator Pruitt announces he is seeking reconsideration from NMFS on their finding for chlorpyrifos. “Pruitt’s push to revisit the opinion has thrust the government into new territory,” according to an analysis by the Washington Post. “Industry officials and environmentalists said they were unsure of the legal process going forward.” NMFS does not say whether they will revisit the opinion, and while EPA would normally act on an endangered species finding by another agency within a year, a deadline was not given in the NMFS opinion.

March 23, 2018 EPA opens a comment period on the Biological Opinion “to inform whether formal reinitiation of consultation on the BiOp is appropriate.” The comment period is open through May 22, 2018, then extended to July 23, 2018.

June 13, 2018 Hawaii becomes the first state to ban the use of pesticides containing chlorpyrifos, effective Jan. 1, 2019. The new law also establishes 100-foot buffer zones around schools and prohibits the spraying of certain pesticides, including chlorpyrifos, during normal school hours. Businesses will be able to apply for a three-year extension to adjust to the new law.

Aug. 9, 2018 The US Court of Appeals for the Ninth Circuit rules that EPA revoke all tolerances and cancel all registrations for chlorpyrifos within 60 days. The court finds “There was no justification for the EPA’s decision in its 2017 order to maintain a tolerance for chlorpyrifos in the face of scientific evidence that its residue on food causes neurodevelopmental damage to children.”

Sep. 24, 2018 EPA requests that the Ninth Circuit grant a rehearing of the August decision by the three-judge panel or en banc.

Nov. 15, 2018 California’s Department of Pesticide Regulation issues temporary guidelines for chlorpyrifos that include banning it from crop dusting and discontinuing its use on most crops.

Dec.17, 2018 Senator Brian Schatz from Hawaii introduces a bill that would ban restricted-use or organophosphate pesticides, including chlorpyrifos, from being sprayed near schools – essentially taking Hawaii’s prohibition on the use of chlorpyrifos near schools nationwide.

Feb. 6, 2019 The Ninth Circuit grants a rehearing of the decision en banc, meaning a panel of 11 judges will rehear the case.

March 26, 2019 The case is argued and submitted to a panel of eleven judges in the rehearing at the Ninth Circuit. A decision is pending.

April 11, 2019 Senator Kirsten Gillibrand introduces a bill, “Safe School Meals for Kids Act of 2019,” to keep food treated with chlorpyrifos out of school meal programs nationwide.

April 19, 2019 The Ninth Circuit en banc panel orders EPA to respond to the administrative objections submitted by environmental and farmworkers’ groups to the EPA when it decided not to ban chlorpyrifos. EPA’s response to the objections, due within 90 days, can be challenged before the same panel of judges at the Ninth Circuit.

April 30, 2019 New York legislators pass twin bills, Senate bill S5343 and Assembly bill A2477B, which ban chlorpyrifos use in the state by 2021. The bills will be sent to the governor to be signed into law.

May 8, 2019 California announces that it is seeking to cancel state registration of chlorpyrifos. The state is beginning an administrative process to cancel registrations for products containing chlorpyrifos and also working to identify safer alternatives to avoid its replacement with a similarly harmful pesticide.

July 18, 2019 EPA announces that it will not ban chlorpyrifos. It responds to the environmental and farmworkers’ groups’ objections, as required by the Ninth Circuit, and denied them by saying that the health risks they identified were “not supported by valid, complete, and reliable evidence.”

Aug. 7, 2019 Seven states and the District of Columbia file a petition for the Ninth Circuit to review EPA’s Objection Denial Order (July 2019). New York v. Wheeler, No. 19-71982 (9th Cir.).

Aug. 7, 2019 Environmental and farmworkers’ groups file a petition for the Ninth Circuit to review EPA’s Objection Denial Order (July 2019) and Petition Denial Order (April 2017). LULAC v. Wheeler, No. 19-71979 (9th Cir.).

Aug. 14, 2019 California moves to ban chlorpyrifos. The ban will take effect in 15 days unless an opposing party requests an administrative hearing.

Oct. 9, 2019 California’s Department of Pesticide Regulation and pesticide manufacturers reach an agreement to stop all sales of chlorpyrifos in February 2020 and ban all possession and uses of the pesticide in California on Dec. 31, 2020.

Oct. 16, 2019 The Ninth Circuit decides that the latest round of litigation filed by states and environmental and farmworkers’ groups challenging EPA’s Petition and Objection Denial Orders are “comeback” cases and therefore will be heard by the same panel of judges that presided over the previous case.

Dec. 6, 2019 The European Union votes to ban the sale of chlorpyrifos after Jan. 31, 2020.

Feb. 6, 2020 Pesticide manufacturer Corteva announces that it will stop making chlorpyrifos.

Feb. 19, 2020 Maryland’s Department of Agriculture announces a plan to phase out the use of chlorpyrifos.

Sep. 22, 2020 EPA releases its draft risk assessment of chlorpyrifos for public review in preparation for the 60-day comment period to begin sometime in October 2020. 

Oct. 20, 2020 California family files a civil lawsuit in Kings County Superior Court against Corteva, alleging their son’s neurological injuries were caused by exposure to chlorpyrifos and seeking to recover damages (Case No. 20C-250). Lawyers for the family expect additional plaintiffs to join the suit over the next month.

Dec. 3, 2020 EPA proposes an interim decision recommending some label changes and usage restrictions for chlorpyrifos, such as new advisory language about the risk of spray drift. EPA is accepting comments on the proposal until Feb. 5, 2021 and comments may be submitted here

Early Biden Actions

Jan. 20, 2021 President Biden signed Executive Order 13990, “Protecting Public Health and the Environment and Restoring Science To Tackle the Climate Crisis,” instructing agencies to review agency actions during the Trump administration for consistency with the new administration’s policies and consider suspending, revising, or rescinding them. The new administration also included the decision not to ban chlorpyrifos in the accompanying list of regulatory actions it would review pursuant to the EO.

Feb. 5, 2021 The Biden administration extended the public comment period on the Dec. 3, 2020 draft risk assessment and proposed interim decision for chlorpyrifos through March 7, 2021.