On March 17, 2021, the U.S. Environmental Protection Agency (EPA) announced the issuance of the final guidance document entitled "Guidance for Waiving Acute Dermal Toxicity Tests for Pesticide Technical Chemicals & Supporting Retrospective Analysis" (EPA 705-G-2020-3722; Docket ID: EPA-HQ-OPP-2016-0093) that expands the potential for data waivers for acute dermal studies to single technical active ingredients (AI) used to formulate end-use products. This new guidance builds upon the final guidance for waiving acute dermal toxicity tests for pesticide formulations published by EPA on November 9, 2016, and is an example of EPA’s continued efforts to reduce animal testing and achieve its goal of eliminating all EPA requests for studies and EPA funding of studies on mammals by 2035.  EPA states that this guidance is expected to reduce the number of test animals used annually by approximately 750, as well as save EPA, industry, and laboratory resources.

The new final guidance document also allows EPA to harmonize with the Pest Management Regulatory Agency (PMRA) of Canada, which published guidance on acute dermal toxicity waivers for both end-use product formulations and technical chemicals in 2017. 

In developing the new guidance, EPA states that the Office of Pesticide Programs (OPP) and the National Toxicology Program (NTP) Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) conducted a retrospective analysis of rat acute oral and acute dermal LD50 studies for 249 AIs across numerous chemical classes and toxicity categories in the EPA pesticide categorization scheme.  The overall purpose of this analysis was to address the utility of the acute dermal toxicity study for single AIs in pesticide labeling, such as the signal word and precautionary statements. Fumigants and rodenticides were excluded from this retrospective analysis based on their physical state and/or anticipated exposures to them. EPA concluded that:

• For 67 percent of the 249 technical chemicals, the results of both oral and dermal acute toxicity studies fall within the same Toxicity Category; 

• For 32 percent of the chemicals, the oral study falls within a lower (i.e., more protective) Toxicity Category;

• Thus, for 99 percent of the chemicals in the analysis, if the dermal study had not been available and labeling had been based only on the Toxicity Category for the oral acute toxicity study, the labeling requirements would have been equally or more protective; 

• For the two remaining chemicals (less than 1 percent), factors other than the dermal acute toxicity may influence labeling requirements; and

• The acute dermal toxicity studies provide little to no added value in regulatory decision making. 

EPA states that it believes the retrospective analysis fully supports the conclusion that waivers may be granted for acute dermal toxicity studies for pesticide technical chemicals, except for fumigants and rodenticides.  Waivers may be accepted for fumigants and rodenticides on a case-by-case basis with appropriate scientific rationale. EPA maintains the ability to request acute dermal toxicity data on a case-by-case basis, but states that it anticipates granting the waiver in most cases.

Additional information on EPA’s efforts to reduce animal testing is available here.