EPA Implements Mitigation Measures for Insecticides Chlorpyrifos, Diazinon, and Malathion to Protect Endangered Species

The U.S. EPA is implementing measures to protect federally threatened or endangered (listed) species and their designated critical habitats from the effects of the insecticides chlorpyrifos, diazinon, and malathion. The measures include changes to pesticide labeling requirements and issuing of Endangered Species Protection Bulletins that set geographically specific limitations on pesticide use.

Chlorpyrifos, diazinon, and malathion are organophosphate insecticides commonly used to control foliage and soil insect pests. Pesticide products containing chlorpyrifos are registered for use on agricultural crops and on nonfood sites such as ornamental plants in nurseries, golf course turf, or as wood treatment. Diazinon is used on a variety of fruit and vegetable crops, orchards, outdoor nurseries, and in cattle ear tags to control flies. There are no residential uses of chlorpyrifos or diazinon. Malathion is used in the production of a wide variety of food and feed crops to control many types of insects such as aphids, leafhoppers, and Japanese beetles, by home gardeners for outdoor residential uses including to protect vegetable gardens, fruit trees, and a variety of ornamentals, as well as for controlling mosquitoes.

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Mosquito-borne diseases, such as those caused by the West Nile and Zika viruses, are among the world’s leading causes of illness and death and pose a significant risk to people in the United States. Climate change also increases the risk of human exposure to mosquito-borne diseases, as studies show that warmer temperatures associated with climate change can expand the range and breeding season of mosquitoes, as well as accelerate mosquito development, biting rates, and the incubation of the disease within a mosquito. Using pesticides like malathion to control mosquito populations is important to maintaining public health, particularly in densely populated areas in overburdened communities.

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Under the Endangered Species Act, EPA is responsible for ensuring that its actions – including many pesticide registration actions — do not jeopardize listed species or destroy or adversely modify their critical habitats. When EPA determines in its biological evaluation that a pesticide may affect these species or habitats, EPA must consult with the National Marine Fisheries Service (NMFS), the U.S. Fish and Wildlife Service, or both (collectively referred to as the “Services”). Once consultation is complete, the Services develop a Biological Opinion (BiOp) that, among other things, determines if the pesticide is expected to jeopardize listed species or adversely modify their critical habitats, and if so, require measures to protect these species and habitats.

For chlorpyrifos, diazinon, and malathion, EPA determined in 2022 that the currently registered uses of these insecticides have the potential to adversely affect one or more listed species. After consultation between EPA and NMFS, and the chlorpyrifos, diazinon, and malathion registrants, on June 30, 2022, NMFS issued a “no jeopardy” BiOp for all three pesticides. During that consultation, the registrants committed to amend their product labels and registrations to include measures that reduce runoff and spray drift from treated areas into species’ habitats. EPA also committed to issuing Endangered Species Protection Bulletins, available on the Bulletins Live! Two website, which set forth geographically specific pesticide use limitations that would protect listed species and their critical habitats.

Bulletins for all three pesticides include restrictions on when to apply and restrictions on tank mixing. The mitigations included in the Bulletins for diazinon only include use limitations related to runoff, whereas the mitigations for chlorpyrifos include use limitations related to both runoff and drift. The chlorpyrifos and diazinon Bulletins also include wind speed restrictions. The malathion Bulletins include a requirement to maintain a buffer between application area and specific habitats, with the size of the required buffer depending on the application rate, application method, and wind direction.

Registrants have submitted these product labeling amendments to EPA, as well as amendments describing how to report ecological incidents associated with pesticide applications, should users observe any. Amended label guidance will be included on the next printing of product labels, with a 12-month existing stock provision included in the agreement. EPA has also posted agreed-upon Bulletins. Collectively, these measures will not only protect listed species but also reduce exposure to non-listed species.

At this time, labels have been approved for chlorpyrifos products with only non-food uses. EPA requested and NMFS granted an extension to August 2024 to implement the BiOp with updates for those labels with food uses. This will allow EPA the additional time needed to cancel all food uses except for the 11 food crops specified previously in EPA’s 2020 chlorpyrifos Proposed Interim Decision.

For additional information on the NMFS BiOp for these three insecticides, visit EPA’s website. The registration review process for chlorpyrifos, diazinon, and malathion is ongoing. In early 2025, EPA plans to issue an amended Proposed Interim Decision (PID) for chlorpyrifos for public comment followed by an Interim Decision (ID) in late 2025. EPA plans to issue the malathion Proposed Final Decision in July 2024 and the Final Decision in January 2025. In late 2025/early 2026, EPA plans to issue a PID for diazinon followed by the ID in the summer of 2026.

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