The U.S. Environmental Protection Agency (EPA) is announcing new mitigation measures for the organophosphate pesticide diazinon. The Agency worked with the registrants of this pesticide to develop these measures early, several years ahead of the normal registration review process, to protect farmworkers and other people that work with this pesticide from serious health risks after EPA released an updated occupational risk assessment that found diazinon posed potential risks of concern to workers who mix, load, and apply the pesticide, and to bystanders (including farmworkers) who could be exposed to spray drift.
Adama US and Drexel Chemical Company—the technical registrants of diazinon—have agreed to voluntary mitigation measures that will make application and site maintenance safer, including the cancellation of aerial applications, backpack and mechanically-pressurized handgun applications, and wettable powder formulation. The commitment of the registrants also includes spray drift reduction measures, including buffer restrictions for residential and institutional sites to reduce exposure to bystanders. EPA has received amended labels for review and appreciates the cooperation of these registrants in discussing and adopting mitigation measures.
Diazinon is an insecticide used on a variety of fruit and vegetable crops, orchards, outdoor nurseries and cattle ear tags. This pesticide is currently undergoing registration review, a process that requires EPA to reevaluate pesticides every 15 years to ensure that as the ability to assess risk evolves and as policies and practices change, pesticides continue to meet the statutory standard of causing no unreasonable adverse effects on human health or the environment.
In March 2023, EPA announced that it would seek to take accelerated and early action to address these risks, even though registration review for this pesticide will not conclude until 2026.
EPA also released updated occupational risk assessments for three other organophosphate pesticides—ethoprop, tribufos, and phosmet—in March 2023 ahead of the normal registration review schedule. The assessments also showed that some uses of these pesticides posed health risks to workers who mix, load, and apply the pesticide, and to bystanders (including farmworkers) who could be exposed to spray drift. EPA is pursing early mitigation action for these three pesticides outside of the normal registration review process. The Agency is actively working with the registrants of these three pesticides to identify appropriate mitigation measures and hopes to reach agreements on those cases within the next several weeks.
Stakeholders will have an opportunity to comment when the case progresses through the next step of registration review with the proposed interim decision, which will include the full updated human health risk assessment. Per the registration review process, this proposed decision will be followed by an interim or final decision which will contain additional label mitigation measures for risks not covered by the early mitigation initiative. EPA expects to issue the proposed interim decision for diazinon in fiscal year 2026.
The updated diazinon risk assessment is available in the registration review docket EPA-HQ-OPP-2008-0351 at www.regulations.gov.
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