US EPA releases updated occupational exposure assessments for seed treatment uses for three neonicotinoids

On July 26, 2024, the U.S. Environmental Protection Agency (EPA) is releasing its updated occupational exposure assessments for handling and treating seeds with clothianidin, imidacloprid, and thiamethoxam, which belong to a class of pesticides called ″neonicotinoids.″ Neonicotinoids are systemic insecticides that work by disrupting the central nervous system of insects. If humans are exposed to very high amounts of neonicotinoids, they could also experience harmful effects such as neurotoxicity (e.g., tremors and decreased motor activity), reproductive, or developmental effects. These pesticides are used on a wide variety of crops, turf, ornamentals, pets (i.e., flea treatments), and other residential and commercial indoor and outdoor uses. There are also over 100 different seed treatment products that contain clothianidin, imidacloprid, or thiamethoxam, which are used to control chewing and sucking insects that can cause significant damage to seeds and young plants soon after planting.

Since the issuance of the 2020 proposed interim decisions (PIDs) for these three neonicotinoids, EPA has updated the occupational exposure assessments for handling and treating seeds with the pesticides by incorporating new data on the extent to which workers treating these seed are exposed to them. These data were submitted by the Agricultural Handler Exposure Task Force (AHETF), a consortium of agricultural chemical companies that jointly develop worker exposure data for pesticides. The AHETF provided additional information on dermal and inhalation exposure to workers in various seed treatment related worker tasks. Using the new data in the updated occupational assessments results in higher worker exposure and risk estimates for various seed treatment tasks than were previously estimated and presented in the 2020 PIDs.

Based on these updated occupational risk assessments, EPA has identified several activities associated with seed treatment that can pose risks from dermal or inhalation exposures to workers for these three neonicotinoids. The majority of these risks result from commercial seed treatment, particularly the cleaning of seed treatment equipment, even when the use of maximum personal protective equipment is considered.

Next Steps

EPA is accepting public comments on the updated occupational exposure assessments for 60 days, closing the comment period on September 24, 2024. The amended proposed interim decisions (PIDs) for these neonicotinoids are anticipated in 2025. And the registration review documents can be found at www.regulations.gov in the following dockets:

Clothianidin: EPA-HQ-OPP-2011-0865

Imidacloprid: EPA-HQ-OPP-2008-0844

Thiamethoxam: EPA-HQ-OPP-2011-0581

A reader’s guide entitled Clothianidin’s, Imidacloprid’s, and Thiamethoxam’s Updated Occupational Exposure Assessments for Seed Treatment Uses: Guide to Commenters will also be placed within each of the above dockets to provide commenters with guidance on the types of information the Agency is seeking.