EPA Seeks Public Comment on Measures to Address Human Health and Ecological Risks Posed by Diuron
Released on April 28, 2022
The U.S. Environmental Protection Agency (EPA) is releasing the proposed interim decision (PID) for the pesticide diuron. The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) requires EPA to review pesticides every 15 years to ensure that risk assessments reflect the best available science, and to ensure that registered products in the marketplace do not present unreasonable adverse effects to human health and the environment. The PID is part of a multi-step process to identify risks of concern as well as actions that can mitigate these risks.
Diuron is used as an herbicide to control annual and perennial broadleaf and grassy weeds in a variety of agricultural sites and non-agricultural sites (e.g., rights-of-way, utilities, and roadways) as well as a harvest aid (defoliant) in cotton and an algaecide in commercial fish production. The pesticide also has antimicrobial uses as a mildewcide and materials preservative in paints, stains, coatings, adhesives, and sealants.
The 2021 revised draft human health risk assessments identified dietary and aggregate (i.e., combined dietary and residential painting exposures) cancer risks of concern when used on crops, non-agricultural sites, and residential exterior paint uses. These risk assessments also identified occupational non-cancer and cancer risks of concern from use on crops and occupational cancer risks of concern from paint uses. Additionally, the 2021 revised ecological risk assessments identified risks of concern to birds and mammals (from consumption of food items on treated fields and off-field risk from spray drift); to terrestrial plants (from runoff and spray drift from treated fields); and to fish, aquatic invertebrates, and aquatic plants (from runoff and sediment from treated fields and from exterior paint uses).
- Based on the revised draft risk assessments and feedback submitted during the public comment period, EPA is proposing the following new measures to mitigate the ecological, dietary, and aggregate cancer risks of concern:
- Terminate all herbicide uses on food and feed crops to address dietary and aggregate risks of concern to the general public and ecological risks of concern;
- Terminate all herbicide uses on non-food agricultural sites (e.g., ornamentals) and on all non-agricultural sites (e.g., rights-of-way, utilities, roadways) to address dietary and aggregate risks of concern to the general public and ecological risks of concern; Terminate the use as an algaecide for commercial fish production to address dietary risks of concern; and
- Revoke all food and feed tolerances to address dietary risks of concern to the general public (except for a single tolerance to support the remaining cotton harvest aid use).
There are many alternative herbicides available for important use sites such as cotton, asparagus, blueberry, citrus, and non-agricultural sites. More limited alternatives are available for use on pineapple and in commercial fish production.
EPA also identified risks of concern for occupational painters, and the Agency is proposing new mitigation measures that:
- Reduce application rates;
- Require personal protective equipment (PPE) language to be included on the paint can labels to protect occupational painters using airless spraying equipment; and
- Require registrant-sponsored applicator stewardship plans aimed at educating occupational painters on the proper use of PPE while using such equipment.
EPA is not proposing changes at this time to diuron’s registrations as a cotton harvest aid (defoliant) and use in aquariums/containerized ponds in residential settings because these uses don’t present dietary or aggregate risks of concern. The Agency will also allow for the continued use of diuron for the antimicrobial uses because the proposed mitigation addresses risks of concern for painters and reduces ecological risks.
Upon publication of the Federal Register notice, public comments will be accepted for 60 days in the diuron registration review docket ID number EPA-HQ-OPP-2015-0077 at www.regulations.gov. EPA will carefully consider public input when evaluating the proposed PPE and stewardship plans as these mitigation measures will likely be used to mitigate risks for other biocides used in paints and coatings.
After considering comments on the PID, the next step in the registration review process will be to proceed with the interim decision, which finalizes any required risk mitigation measures to address human health and ecological risks of concern.