The U.S. Environmental Protection Agency (EPA) is releasing the proposed interim decision (PID) for the pesticide diuron.

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.

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.

For the complete EPA notice, click here.