On November 2, 2023, the Eighth Circuit Court of Appeals issued its decision in Red River Valley Sugarbeet Growers Ass’n v. Regan, No. 22-1422 (8th Cir. 2023), reinstating the use of the pesticide chlorpyrifos on food crops. In 2021, the Environmental Protection Agency (“EPA”) revoked the food tolerances for chlorpyrifos after a decision from the Ninth Circuit Court of Appeals instructed the agency to either revoke or modify the tolerances. Without a specified food tolerance, a pesticide may not be used on crops intended for food production. After EPA revoked the tolerances for chlorpyrifos, several farm groups filed a lawsuit against EPA challenging that decision and asking that the tolerances be reinstated. The Eighth Circuit’s recent decision has granted that request.


Chlorpyrifos was originally registered for use by EPA in 1965. It is an organophosphate that has been used on a wide range of crops, including corn, soybeans, cotton, various vegetables, and fruit and nut trees. Chlorpyrifos is an insecticide that has primarily been used to control foliage and soil-borne pests, as well as termites, mosquitoes, and roundworms. In 2021, EPA revoked the food tolerances for chlorpyrifos, effectively making it unavailable for agricultural use.

Before a pesticide may be legally used or sold in the United States, it must be registered under the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”). To register a pesticide, EPA must determine that using the pesticide in its intended manner will not cause “unreasonable adverse effects on the environment.” 7 U.S.C. § 136a(c)(5)(C). Under FIFRA, “unreasonable adverse effects on the environment” is defined as “(1) any unreasonable risk to man or the environment […] or (2) a human dietary risk from residues that result from a use of a pesticide in or on any food inconsistent with the standard under section 346a” of the Federal Food, Drug, and Cosmetic Act (“FFDCA”). 7 U.S.C. § 136(bb). In other words, in order to register a pesticide product for use on food crops, EPA must ensure that the pesticide will not violate standards established under the FFDCA.

The primary purpose of the FFDCA is to oversee and regulate the production of food, drugs, and cosmetics within the United States. While the Food and Drug Administration is responsible for implementing the majority of the FFDCA, section 408 of the statute allows EPA to set tolerances for pesticide residues on food. A “tolerance” refers to the maximum level of pesticide residue that is legally allowed to remain in or on raw agricultural commodities and processed foods. If a pesticide does not have an established tolerance, food crops treated with that pesticide are considered unsafe and may not be introduced into interstate commerce. 21 U.S.C. § 346a(a)(1); 21 U.S.C. § 331(a).

According to the FFDCA, EPA may only establish a pesticide tolerance if it determines that the tolerance is “safe.” If EPA uncovers evidence showing that the tolerance is not safe, it must either revoke or modify that tolerance. 21 U.S.C. § 346a(b)(2)(A)(i). In the context of pesticide tolerances, the FFDCA defines “safe” as “a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical reside, including all anticipated dietary exposures and all other exposures for which there is reliable information.” 21 U.S.C. § 346a(b)(2)(A)(ii). If EPA finds that it is no longer reasonably certain that a pesticide tolerance will not cause harm, it must either modify or revoke that tolerance.

In 2021, the Ninth Circuit issued its decision in a case titled League of United Latin Am. Citizens v. Regan, No. 19-71979 (9th Cir. 2021). That case stemmed from a petition that the plaintiffs had submitted to EPA in 2007 asking the agency to review the tolerances for chlorpyrifos after the publication of studies suggesting that exposure to chlorpyrifos at the current tolerance levels caused neurodevelopmental effects in children. In League of United Latin Am. Citizens v. Regan, the plaintiffs challenged EPA’s denial of their petition, arguing that the denial had violated FIFRA and the FFDCA. The Ninth Circuit agreed, finding that the FFDCA requires EPA to review a pesticide tolerance any time the agency became aware of “genuine questions” as to the tolerance’s safety. The court directed EPA to review the current chlorpyrifos tolerance and either modify or revoke the tolerances by the end of sixty days. For an in-depth look at that decision, click here.

EPA issued a final rule to revoke the tolerances for chlorpyrifos in August 2021, and over the course of the next year proceeded to formally cancel uses of chlorpyrifos on food crops. In February 2022, a coalition of farm groups filed a lawsuit in the Eighth Circuit Court of Appeals challenging EPA’s decision to revoke the chlorpyrifos tolerances and cancel its uses on food crops. The groups argued that EPA took too broad an approach to the Ninth Circuit’s order. Instead of completely revoking the tolerances, the farm groups argued that EPA should have reviewed and modified the tolerances to allow some uses that EPA had previously identified as safe. The Eighth Circuit agreed and directed EPA to reinstate the chlorpyrifos tolerances.

The Court’s Decision

In Red River Valley Sugarbeet Growers Ass’n v. Regan, the Eighth Circuit concluded that EPA’s decision to revoke the tolerances for chlorpyrifos was unlawful because the agency had failed to exercise “the full scope of its discretion.” To reach this conclusion, the court relied on findings that EPA had made in document the agency published in 2020 as part of the chlorpyrifos registration review.

Once a pesticide has been registered under FIFRA, the statute directs EPA to review the registration every fifteen years to ensure that the pesticide continues to meet FIFRA’s “unreasonable adverse effects” standard. Registration review for chlorpyrifos was initiated in 2006. As part of that review, EPA issued a Proposed Interim Registration Review Decision (“PID”) in 2020 which, among other things, examined the safety of chlorpyrifos tolerances. In the 2020 PID, EPA identified eleven “high-benefit agricultural uses” for chlorpyrifos that the agency determined could retain their safety tolerances. However, before EPA could finalize the PID into a final interim registration decision, the Ninth Circuit issued its order in League of United Latin Am. Citizens v. Regan and placed a sixty-day deadline on EPA to either modify or revoke all chlorpyrifos tolerances. Faced with this deadline, EPA chose to revoke the tolerances instead of exploring whether any could be modified for continued use.

According to the Eighth Circuit, by failing to explore the possibility that some chlorpyrifos tolerances could be retained, EPA took “too-narrow” a view of its own authority. The court noted that EPA itself had identified eleven uses in the 2020 PID that were likely to meet the safety requirements of the FFDCA. While the court acknowledges that the deadline imposed by the Ninth Circuit placed an additional burden on EPA, it was still no excuse for “zeroing in on a single solution to the exclusion of others.” Because EPA failed to explore whether modifying some chlorpyrifos tolerances to maintain some uses of the pesticide, the Eighth Circuit determined that EPA’s actions were unlawful, and reinstated all tolerances for chlorpyrifos.

Going Forward

While the Eighth Circuit’s order would overturn EPA’s 2021 revocation of chlorpyrifos tolerances, it is still unclear when farmers will be able to use the insecticide. EPA may choose to appeal the court’s decision, or take other steps that could delay when chlorpyrifos becomes available for use. The agency may also explore modifying the tolerances for chlorpyrifos, which could ultimately see some uses of the pesticide reinstated while others could remain unavailable.


To read the court’s decision in Red River Valley Sugarbeet Growers Ass’n v. Regan, click here.

To read the text of FIFRA, click here.

To read the text of the FFDCA, click here.

For more National Agricultural Law Center resources on pesticides, click here.