U.S. Regulators Nix Chlorpyrifos, Neonicotinoids Are Next

In August the U.S. EPA released a final rule revoking all tolerances for chlorpyrifos in food, effectively banning the substance in agriculture. Non-agricultural uses are unaffected by the final tolerance rule, although those uses continue to be evaluated with a final rule scheduled for 2022. 

The state of California had already phased out chlorpyrifos for agricultural use in 2020, citing the state’s independent Scientific Review Panel on Toxic Air Contaminants, which found that the substance is a developmental neurotoxin in children and sensitive populations.  


The rule becomes effectiveOctober 29, 2021, but tolerance revocations for all commodities will not become effective until February 28, 2022, a date chosen so the U.S. can satisfy international trade obligations, according to EPA.  

The new policy deviates from the standard regulatory process that requires the EPA to accept public comments on a draft evaluation before issuing a final rule. The risk determination was ordered by the Ninth Circuit court as a result of a 2007 Petition from the Pesticide Action Network North America and the Natural Resources Defense Council requesting that EPA revoke all chlorpyrifos tolerances.  

Though the use of the substance had been on the decline, it is still one of the most widely used insecticides in the U.S., and it could provide the ammunition needed for regulators to further scrutinize the contentious organophosphate class of chemistries as endocrine disruptors. The organophosphate class was re-evaluated in 2008 and is subject to periodic review by the EPA as it is directed to do under The Federal Insecticide, Fungicide, and Rodenticide Act. Other organophosphates include malathion, diazinon, dichlorvos, and phosmet. Parathion is already banned for any use in the U.S., and azinphos-methyl has been banned in Europe since 2006. 

The EPA based their decision on studies that showed exposure was linked to lower birth weights and hampered brain development in children, ruling there is “uncertainty around the potential for pre- and post-natal toxicity for infants and children in the area of neurodevelopmental outcomes.” 

The ruling is part of a series of moves by the new administration to strengthen environmental regulations that were suspended or overturned by the previous administration, and the Endangered Species Act will be a key mechanism to re-evaluate substances. According to EPA: “As we move forward with these reviews, we will be paying special attention to effects on endangered species, based on the better understanding of these classes of pesticides that we and stakeholders have developed.” 

Just days after banning chlorpyrifos, EPA released draft evaluations identifying three neonicotinoids as likely harmful to the majority of endangered plants and animals, including all 38 endangered amphibians.

The draft evaluations for clothianidin, imidacloprid, and thiamethoxam will now be made available for the customary public comment period before final rules are decided, but the “likely to adversely affect” determination means that EPA reasonably expects that at least one individual animal or plant, among a variety of listed species, may be exposed to the pesticide at a sufficient level to have an adverse effect, which could lay the groundwork for limiting the use of the three AIs and have implications for the broader class of neonicotinoids, which are already under scrutiny for affecting non-target species, notably pollinators. 

“EPA has begun the process of proposing mitigation measures, such as annual application rate reductions and application timing restrictions under the Federal Insecticide, Fungicide, and Rodenticide Act, which will be finalized after the completion of the final [biological evaluations].” 

The moves represent a clear priority for the Joe Biden administration, which issued a set of executive orders during his first days in office to strengthen environmental protections that were suspended by the previous administration. The chlorpyrifos assessment was one of the first among them, and it appears it will not be the last.