Chlorpyrifos Petition Denial

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Why it Matters

Chlorpyrifos is an organophosphate pesticide used since 1965 on food and oil crops, and cotton – and on golf courses. It is the most widely used conventional pesticide in the United States. Over time, the Environmental Protection Agency (EPA) has narrowed the acceptable uses for this pesticide, as research revealed serious health risks. For instance, in 2000, the EPA banned the use of chlorpyrifos for household use (except for child resistant ant and roach traps) and on tomatoes.

Current Status

On April 5, 2017 EPA formally denied a petition by environmental groups to ban all food applications of the pesticide, and stated it will delay reassessment until the statutory deadline of October 1, 2022. On April 5, 2017 environmental groups filed a motion with the Ninth Circuit asking the court to enforce EPA’s deadline to respond to their petition to ban the chemical, arguing EPA presented no new evidence that the chemical was safe. On June 5, 2017 NRDC and other environmental groups as well as seven states filed an administrative appeal with EPA “challenging the agency’s failure to finalize the ban on chlorpyrifos.” The Ninth Circuit appeal was rejected on July 18, 2017. 


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

In 1996, Congress strengthened both laws in the Food Quality Protection Act, which passed the House and Senate unanimously. The Food Quality Protection Act directed EPA to build in a large safety buffer in its periodic risk assessments to capture the risks of pesticide exposure to children, and consider cumulative risk. EPA had to assess risk for nearly 10,000 pesticides using these new factors; the agency has revoked or modified 4,000 assessments.

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

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

On July 22, 2010 NRDC and PANNA filed a lawsuit in federal court, challenging EPA’s failure to respond. NRDC v. EPA, No. (S.D. NY)

The case was stayed when EPA agreed to issue a human health risk assessment and respond to the petition by November 2011.

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

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

Meanwhile, in April 2016 the FIFRA Scientific Advisory Panel (SAP) had met and discussed research on chlorpyrifos. The SAP concluded that the point of departure (the dosage of the pesticide at which there aren’t observable effects) in EPA’s risk assessment was not protective enough.

On November 17, 2016 EPA issued a brief Notice of Data Availability and suggested it would change the point of departure based on SAP input.

Trump Era

On April 5, 2017 EPA formally denied the NRDC/PANNA petition and indicated it will not follow the negotiated schedule for rulemaking but would delay action on chlorpyrifos until the statutory deadline for reassessment (October 1, 2022).

That same day, April 5, 2017, NRDC and PANNA filed 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.

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

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

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

On December 29, 2017 NOAA issued a biological opinion on chlorpyrifos and two other pesticides, stating that they can be harmful to endangered salmon. The opinion was made public by EarthJustice on January 9, 2018. 

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