EPA Enacts Ban on Use of the Pesticide Chlorpyrifos on Food

The U.S. Environmental Protection Agency (EPA) recently released a final rule effectively initiating a ban on the use of the pesticide chlorpyrifos on food. Intended to improve protection of human health, this effort is likely to yield particular benefits for farmworkers and children. In this blog post, we take a look at chlorpyrifos and consider the recent measures undertaken to ban its use.

About Chlorpyrifos

Chlorpyrifos is a toxic organophosphate compound that has seen extensive use as a broad-spectrum pesticide. It is synthesized via the reaction of O,O-diethyl phosphorochloridothioate with 3,5,6-trichloro-2-pyridinol. With its acaricidal, insecticidal, and miticidal properties, chlorpyrifos has proven to be effective in managing many plant-based and soil-borne insect pests.


IUPAC NameO,O-Diethyl O-(3,5,6-trichloropyridin-2-yl) phosphorothioate
Chemical FormulaC9H11Cl3NO3PS
CAS Registry Number2921-88-2

Chlorpyrifos acts by adversely affecting nervous system function. By binding at the cholinesterase enzyme active site, chlorpyrifos inhibits the breakdown of acetylcholine. The resulting toxicity to the insect's neurons leads to eventual death.

Beyond its effects as a pesticide, chlorpyrifos can yield harmful effects to humans and animals as well. Exposure may occur in several ways, including via inhalation, dermal, and oral routes.

Necessary Risk Prevention Measures

In 2007, the Pesticide Action Network North America and Natural Resources Defense Council filed a petition asking that all tolerances for chlorpyrifos be revoked by the EPA. Following denial of the petition by the Agency in 2017, the denial was subsequently challenged in 2019 by the Ninth Circuit Court of Appeals. Earlier this year, it was concluded that the EPA had not met its duties relative to the present tolerances. The Court, therefore, ordered that the petition be granted and a final rule be issued by the EPA.

In a statement from Michael S. Regan, EPA Administrator, he highlighted the significance of the Agency’s actions, noting that “Ending the use of chlorpyrifos on food will help to ensure children, farmworkers, and all people are protected from the potentially dangerous consequences of this pesticide”.

While the final rule revokes all tolerances for chlorpyrifos, it should be noted that the rule does not impact non-agricultural uses of the chemical.

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