On August 19, 2021, the Environmental Protection Agency (“EPA”) announced its intention to publish a final rule in the Federal Register revoking all tolerances for residues of the pesticide chlorpyrifos. This decision comes 14 years after environmental groups filed a petition requesting that EPA revoke all chlorpyrifos tolerances, and four months after a decision from the Ninth Circuit Court of Appeals ordered EPA to make a final decision. The decision is expected to impact only uses of chlorpyrifos on food crops.


The primary purpose of the Federal Food, Drug, and Cosmetic Act (“FFDCA”) is to allow oversight of the safety of food, drugs, medical devices, and cosmetics sold in the United States. Although most of the FFDCA is administered by the Food and Drug Administration (“FDA”), section 408 authorizes EPA to set tolerances for pesticide residues on foods. A “tolerance” refers to the maximum level for residues of pesticides that will legally be allowed in or on raw agricultural commodities and processed foods. Without a tolerance or specific exemption, pesticide residues in or on food are considered unsafe, and such food may not be introduced to interstate commerce. 21 U.S.C. § 346a(a)(1), 21 U.S.C. § 331(a).

According to the FFDCA, EPA may establish or leave in effect a pesticide tolerance only if it determines that the tolerance is safe. If EPA finds that an established pesticide tolerance is unsafe, it must either revoke or modify that tolerance. 21 U.S.C. § 346a(b)(2)(A)(i). In this context, the FFDCA defines “safe” to mean “a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information.” 21 U.S.C. § 346a(b)(2)(A)(ii). In other words, EPA will likely need to revoke or modify a pesticide tolerance if it is no longer certain that exposure to the pesticide at the current tolerance level will not result in harm.

In order for a pesticide to be legally used in the United States, it must first be registered under the Federal Insecticide, Fungicide, and Rodenticide Act (“FIFRA”). To register a pesticide, EPA must determine that doing so will not cause “unreasonable adverse effects on the environment.” 7 U.S.C. § 136a(c)(5). The term “unreasonable adverse effects on the environment” is defined to mean “(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 FFDCA. 7 U.S.C. § 136(bb). Essentially, the definition of “unreasonable adverse effects on the environment” incorporates the FFDCA safety standard into the FIFRA registration process. When EPA registers a pesticide for use, it must determine that doing so will not cause higher amounts of pesticide residue on food commodities than the tolerance levels approved under the FFDCA allow.

After the initial registration, FIFRA requires EPA to re-evaluate registered pesticides every 15 years in a process called “registration review.” 7 U.S.C. § 136a(g). The purpose of the registration review is to “ensure that each pesticide registration continues to satisfy the FIFRA standard for registration,” including the requirement that a registered pesticide “generally will not cause unreasonable adverse effects on the environment.” 40 CFR 155.40(a)(1). Additionally, FIFRA requires all pesticides that were registered before November 1, 1984 to undergo registration review. 7 U.S.C. § 136a-1(a).

How Did We Get Here?

Chlorpyrifos was first registered for use by EPA in 1965, and was most recently found eligible for reregistration in 2006 under section 136a-1 of FIFRA. At that time, EPA concluded that the existing chlorpyrifos tolerances were safe. Shortly afterwards, EPA initiated another registration review of chlorpyrifos in accordance with FIFRA’s 15-year review requirement.

In 2007, environmental interest groups submitted a petition to EPA seeking revocation of all chlorpyrifos tolerances under the FFDCA, and cancellation of all chlorpyrifos pesticide product registrations under FIFRA. According to the petitioners, exposure to chlorpyrifos at the current tolerance levels resulted in neurodevelopmental effects to children. The petition included newly available scientific evidence to support those claims.

EPA did not issue a final decision on the petition until 2017 when the Agency denied the petitioners’ request. In denying the petition, EPA concluded that after several years of study, the science addressing the potential neurodevelopmental effects of chlorpyrifos remained unresolved and that further evaluation of the science was needed. EPA planned to continue evaluating the science while it completed the on-going registration review. Although the petitioners raised objections to EPA’s denial decision, those objections were also denied by EPA in 2019. Following that, the petitioners and several other interest groups filed suit.

The plaintiffs in League of United Latin am. Citizens v. Regan, No. 19-71979 (9th Cir. 2021) challenged EPA’s denial of the 2007 petition, arguing that denial had been unlawful. Ultimately, the Ninth Circuit agreed with the plaintiffs, finding that the FFDCA requires EPA to review a pesticide tolerance once the Agency becomes aware that there are “genuine questions” as to its safety. The court ordered EPA to review the tolerances for chlorpyrifos and issue a final regulation revoking or modifying the tolerances by August 20, 2021. For more information on the Ninth Circuit’s decision, see here.

The Final Rule

EPA issued a prepublication version of its final rule revoking tolerances for chlorpyrifos on August 19, 2021, effectively granting the request in the 2007 petition. The final rule revokes all food tolerances for residues of chlorpyrifos, and is the result of EPA being unable to “make a safety finding to support leaving the current tolerances for residues in place, as required under the FFDCA[.]” Currently, the final rule has not been published in the Federal Register. The revocations of the tolerances will become effective six months after the date the publication.

Following revocation of the tolerances, any food commodities treated with chlorpyrifos and in the channels of trade will be considered adulterated unless the following two factors are satisfied: (1) the residue is present as the result of an application or use of a pesticide at a time and in a manner that was lawful under FIFRA; and (2) the residue does not exceed a level that was authorized under the FFDCA at the time of application. 21 U.S.C. § 346a(l)(5). In other words, once the tolerances of chlorpyrifos are revoked, food commodities containing residue of chlorpyrifos will be considered adulterated, and therefore illegal to sell, unless the residue is the result of an application of chlorpyrifos that was legally conducted under FIFRA at a time when there were tolerances for chlorpyrifos registered under the FFDCA.

Along with issuing a final rule revoking the tolerances, EPA will also issue a Notice of Intent to Cancel under FIFRA to cancel registered food uses of chlorpyrifos. At the moment, EPA has not released a prepublication copy of the Notice, so it is unclear what the specifics will be. However, it is expected that the Notice will prevent chlorpyrifos from being applied to food crops once it takes legal effect. For more information on FIFRA Notices of Intent to Cancel, click here.

Going Forward

EPA’s revocation of chlorpyrifos tolerances and subsequent Notice of Intend to Cancel are expected to apply only to food uses of chlorpyrifos. All other non-food uses of chlorpyrifos will not be affected by the actions EPA is taking regarding the tolerances. Additionally, EPA plans to continue its registration review of the pesticide, which it expects to complete in 2022.

It is currently unclear whether EPA’s decision to revoke chlorpyrifos tolerances will face legal action, or how the decision will impact on-going lawsuits against chlorpyrifos manufacturers.


To read EPA’s final rule revoking chlorpyrifos tolerances, click here.

To read the Ninth Circuit’s decision in League of United Latin am. Citizens v. Regan, click here.

To read the text of FIFRA, click here.

To read section 346a of the FFDCA concerning pesticide tolerances, click here.

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