EPA Adopts Two Non-Animal Testing Methods for Pesticide and Adjuvant Safety Reviews
07 September 2026, Washington, D.C.: The U.S. Environmental Protection Agency announced on August 27, 2026 that it has formally adopted two new scientific methods, known as New Approach Methodologies, that allow the agency to assess certain pesticide and adjuvant safety questions without conducting new animal tests. The move is aimed at speeding up registration and re-registration reviews while advancing EPA’s stated goal of phasing out mammalian animal testing across its chemical safety programs by 2035.
The first method addresses surfactants, a category of adjuvants used in pesticide formulations to help active ingredients wet, spread and penetrate plant surfaces. Instead of testing surfactant formulations on live animals to predict respiratory irritation, EPA will now accept data generated from 3D human airway tissue models combined with computational modeling. These lab-grown tissue models are built from human cells and are designed to mimic how human lung tissue responds to inhaled substances, giving regulators a human-relevant readout without an animal study.
The second method applies the Globally Harmonized System (GHS) mixtures equation, an internationally recognized formula, to estimate the acute oral toxicity of a finished, blended pesticide formulation based on the known toxicity of its individual ingredients, rather than requiring a fresh animal study on the final mixed product. EPA said this approach was validated through a joint analysis with the National Institute of Environmental Health Sciences covering close to 700 pesticide formulations, which demonstrated that the equation reliably identifies products of low toxicity without new testing.
EPA Administrator Lee Zeldin framed the announcement as part of a broader push on testing modernization, saying the agency is “leading the way on eliminating animal testing by embracing cutting-edge, gold standard science.” The announcement builds on a June 2026 EPA release that expanded the list of approved non-animal alternatives available to registrants, suggesting the agency is moving methodically through specific product categories, adjuvants and formulated mixtures being the latest, rather than issuing one blanket policy change.
Animal welfare groups welcomed the decision. Tracie Letterman, Vice President of Federal Affairs at Humane World Action Fund, said the approval shows that eliminating unnecessary animal tests while maintaining scientific integrity is a top priority for the agency. For registrants, the practical effect is narrower and more immediate: companies seeking to register new adjuvant packages or reformulated end-use pesticide products may be able to rely on existing toxicity data for individual components and validated computational models, rather than commissioning new animal studies, potentially shortening development timelines and reducing testing costs for these specific product types.
The announcement did not change requirements for new active ingredient toxicology packages, which still generally require a core battery of studies, some of which involve animal testing where no validated alternative yet exists. It is targeted specifically at adjuvant and formulated-product level assessments, a narrower but commercially significant slice of the registration process given how frequently companies update formulations, add adjuvant packages, or bring generic equivalents to market with new inert ingredient combinations.
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