On 2 November 2023, the 8th Circuit Court of Appeal in Missouri overturned the Environmental Protection Agency's (EPA) decision revoking all tolerances for the organophosphate insecticide chlorpyrifos, following a decision by the 9th Circuit Court of Appeals.

Chlorpyrifos, the most widely used insecticide in the United States in 2017, is a particularly dangerous substance for human health. Once used on crops, it seeps as residues into water and food, and even into the air when it is sprayed. Because of its neurotoxic properties, it is especially dangerous for children, and can lead to a reduction in IQ, memory difficulties and attention deficit disorders, even at lower doses. Tolerances are maximum levels of pesticide residues allowed in or on food regulated by EPA under the Federal Food, Drug, and Cosmetic Act (“FFDCA”).

On 12 September 2007, a group of environmental NGOs petitioned the EPA to revoke all authorisations for the use of chlorpyrifos, without exception. These NGOs argued in particular that there was no "safe level of exposure to chlorpyrifos in early life". In the absence of a response from the EPA, the associations appealed to the 9th Circuit Court of Appeal, which in 2015 ordered the EPA to rule on the issue.

After 10 years of silence, and despite acknowledging that there are "risk concerns" about the impact of chlorpyrifos on children, particularly because the product leaches into drinking water, the EPA has rejected the request to ban chlorpyrifos for lack of "valid, complete and reliable" scientific evidence. While the EPA has not banned the use of chlorpyrifos completely, it has carried out new tests and restricted certain uses.

The environmental NGOs once again turned to the 9th Circuit Court of Appeal to challenge this decision. In a judgment LULAC et al. v EPA dated 29 April 2021, the 9th Circuit Court of Appeals upheld the associations' claims and ordered the EPA, within 60 days, either to modify the chlorpyrifos tolerance thresholds and retain only those examined as being safe, particularly for workers and children, or, if the agency was unable to make such a safety finding, to revoke all tolerances for the use of chlorpyrifos. The EPA opted to revoke all tolerances, stating that it was unable to conclude that the overall exposure risk associated with the use of chlorpyrifos met the FFDCA safety standard. In a decision dated 30 August 2021, the EPA therefore revoked all tolerances for chlorpyrifos, with an exception for residues in human and animal foodstuffs valid until 28 February 2022. For the record, non-agricultural and non-food uses (nurseries, "Christmas trees", ...). remain registered and are currently being sued - CBD vs. US Fish and Wildlife Service ( 4:22-cv-00090-JCH ) - in the Southern District Court of Florida.

On 19 October 2021, the American Farm Bureau Federation (AFBF) filed a petition with the EPA requesting that its ban decision be overturned. Then, the AFBF, along with 19 other farmers' groups, asked the 8th Circuit Court of Appeal to overturn the ban on chlorpyrifos. According to the plaintiffs, the EPA's decision is unlawful, in part because the agency had no new scientific data or analysis to support the decision. Therefore, they are seeking reinstatement of the previous safety tolerance levels for chlorpyrifos. The hearings took place in December 2022. The case remains pending in the 8th Circuit Court of Appeals.

In granting the Plaintiffs' motion, the 8th Circuit Court of Appeal held that a total ban on chlorpyrifos did not necessarily and automatically follow from the April 29, 2021 decision: despite the short 60-day deadline, the EPA also had the option of determining which of the uses of chlorpyrifos were safe for workers and children, so that safe and "high-benefit" uses could have been authorized. As only a partial ban on chlorpyrifos was an option, the EPA should not have “reflexively rejected” this decision.

The decision to authorize chlorpyrifos was therefore remitted to the EPA. The 8th Circuit Court of Appeal did not rule on the merits of the case, i.e. whether all or some of the uses of chlorpyrifos should be banned, and left it to the EPA to make this decision, provided that it "takes into account all the important aspects of the problem" and gives reasons for its decision.

The EPA will allow use on “alfalfa, apple, asparagus, cherry (tart), citrus, cotton, peach, soybean, strawberry, sugar beet, wheat (spring), and wheat (winter) with potential additional restrictions for geographic location, rate of application, farmworker and other vulnerable populations, and vulnerable species and their habitats that may be needed to address safety of the tolerances,” according to a December 19 statement by the agency.