Overview
On December 31, the US Environmental Protection Agency (EPA) issued final guidance describing how the Agency will conduct Endangered Species Act (ESA) assessments for antimicrobial pesticides. The guidance applies to new active ingredients, new uses of registered active ingredients, and registration review actions and is intended to improve the efficiency and predictability of ESA analyses for antimicrobial pesticide products.
The guidance—Final Guidance to Registrants on Activities to Improve the Efficiency of Endangered Species Act Considerations for New Active Ingredient and New Use Registrations and Registration Review for Antimicrobial Pesticides—fulfills EPA's obligations under the Pesticide Registration Improvement Act of 2022 (PRIA 5) and builds on EPA's evolving ESA framework for pesticide registrations.
Scope and Purpose of the Guidance
Although PRIA 5 focuses on "outdoor uses," EPA's final guidance extends to all antimicrobial pesticide uses with the potential for environmental exposure, including certain indoor uses that may result in releases to aquatic or terrestrial environments that are habitat for listed species—for example, the use of antimicrobial pesticides to treat water in industrial settings that is released directly into surface waters. The guidance adapts ESA approaches previously developed for conventional pesticides and biopesticides to antimicrobial pesticides, reflecting EPA's recent experience implementing ESA requirements.
Importantly, the guidance does not create new data requirements or regulatory obligations for registrants. Instead, it outlines the types of information EPA considers in a Biological Evaluation (BE)—EPA's risk assessment for listed species—and identifies opportunities for applicants to proactively engage with EPA to streamline ESA reviews and reduce delays.
Key Takeaways for Registrants
- EPA issued the guidance pursuant to PRIA 5 to improve the efficiency of ESA reviews for antimicrobial pesticide registration and registration review actions involving potential environmental exposure.
- The guidance applies to new antimicrobial active ingredients, new uses of registered actives, and registration review decisions, including certain indoor uses that may result in outdoor exposure.
- EPA describes the information it considers in a BE, including use patterns, geographic footprint (the "action area"), exposure pathways, fate and transport characteristics, and ecotoxicity across taxa.
- Applicants are encouraged to engage early with EPA to clearly define intended use patterns, reduce ambiguity in labeling, and identify potential overlap with listed species or designated critical habitat.
- For many antimicrobial pesticide uses, the action area cannot be specified; the registrant will need to provide EPA with other information about the potential for the pesticide to be released to the environment, and the Agency will need to better explain what other information it will need from registrants.
- EPA emphasizes the importance of precise labeling and limiting supported uses to those the applicant intends to market, as broader or ambiguous use patterns can significantly expand the ESA review scope.
- The guidance highlights the role of label-based mitigation measures—such as best management practices, effluent controls, and geographically tailored restrictions—to avoid or minimize exposure to listed species.
- EPA expects all active ingredients in a product to be evaluated collectively, with mitigation generally driven by the most protective measures needed across co-formulated actives.
- For registration review, EPA encourages registrant coordination and "label clean-up," including alignment on maximum rates, application methods, and mitigation for identical uses, to improve review efficiency.
- The guidance reflects EPA's broader effort to address ESA concerns earlier in the regulatory process rather than deferring key issues to consultation with the US Fish and Wildlife Service or National Marine Fisheries Service.
- While non-binding, the guidance is intended to streamline ESA analyses, improve predictability, and reduce delays by encouraging early consideration of ESA issues during registration and registration review.
- EPA continues to develop its approach for evaluating the potential effects of antimicrobial pesticides on listed species and their critical habitat, and anticipates continued improvement, greater refinement, and additional opportunities for stakeholder engagement.
PRIA 5 Context
PRIA was first enacted in 2004 and has been reauthorized multiple times, most recently in December 2022 (PRIA 5). In addition to revising registration service fees and decision review times, PRIA 5 included new requirements related to farmworker protections, bilingual labeling, and EPA guidance on ESA reviews for certain pesticide actions. EPA's issuance of this final guidance represents a key milestone in implementing those statutory mandates.
Practical Implications
Companies seeking registration or new uses for antimicrobial pesticides—or preparing for registration review—should carefully evaluate their use patterns, labeling, and mitigation strategies in light of EPA's new guidance. Early engagement with EPA and thoughtful consideration of ESA issues may help reduce review timelines and minimize the risk of delays associated with ESA consultations.
Should your company require advice and guidance with the review of EPA's final guidance, experienced professionals at Steptoe are available to help.
