2026-22176·ENVIRONMENTAL PROTECTION AGENCY

Dimethyl Sulfoxide in Pesticide Formulations; Exemptions From the Requirement of a Tolerance

Final RuleEffective

Published: Oct 30, 2026
Effective: Oct 30, 2026
Citation: 91 FR 68480
Docket: EPA-HQ-OPP-2026-0529, FRL-13642-01-OCSPP

Final rule.

Summary

The rule eliminates the need to set a maximum residue limit (“tolerance”) for dimethyl sulfoxide (DMSO) when it is used as an inert ingredient—such as a solvent or co‑solvent—in pesticide products applied to growing crops, to harvested commodities, to animals, and in antimicrobial products that clean food‑contact surfaces in restaurants, dairy‑processing plants, and other food‑processing equipment. EPA concluded that, under the specified conditions, residues of DMSO do not present an unreasonable risk to human health or the environment, so a formal tolerance is unnecessary. The regulation was issued by the U.S. Environmental Protection Agency. It primarily affects manufacturers of pesticide and antimicrobial formulations, farmers and animal producers who use those products, and companies that produce or operate food‑contact equipment that may be treated with DMSO‑based cleaners. The final rule was published in the Federal Register on October 30, 2026 (91 FR 68480) and became effective the same day. The rule implements a petition submitted by Gaylord Chemical Company, LLC, and no further public comment period is open; EPA will now enforce the exemptions and may continue to review any new data that could affect the safety assessment.

AI-generated summary — verify against the Federal Register text.

Official abstract

This regulation establishes exemptions from the requirement of a tolerance for residues of dimethyl sulfoxide (CAS Reg. No. 67-68-5) when used as an inert ingredient (solvent/cosolvent) in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest, in pesticide formulations applied to animals, and in antimicrobial formulations applied to food-contact surfaces in public eating places, dairy-processing equipment, and food- processing equipment and utensils. Spring Regulatory Sciences on behalf of Gaylord Chemical Company, LLC submitted a petition to EPA under the Federal Food, Drug, and Cosmetic Act (FFDCA), requesting establishment of exemptions from the requirement of a tolerance. This regulation eliminates the need to establish maximum permissible levels for residues of dimethyl sulfoxide when used in accordance with the terms of those exemptions.