Animal welfare initiatives have focused on refinement of the use of the dog as a required species for agrochemical toxicity testing.  Previous science and regulatory advocacy efforts resulted in the removal of the one-year dog as a core requirement for agrochemical registrations. A 2021 Center for Alternatives to Animal Testing (CAAT) workshop was developed to address the ongoing question of whether the 90-day non-rodent toxicity study (OECD TG 409, OPPTS 870.3150), for which the dog is the selected species, is a critical and necessary requirement for agrochemical registrations.  As part of this workshop, presenters provided their perspectives on:  the value of the 90-day dog study in a retrospective analysis of active substance registrations in the US, the relevance of dog studies for derivation of reference doses from active substances reviewed by EFSA, current approaches for use of the dog species for pharmaceutical development, <i>in vitro </i>tools that provide species specific information on toxicity and human relevance, and the use of toxicokinetic and PBPK modeling as endpoints in a decision tree approach to determine if the 90-day dog study would be of value to assess human safety and risk. The decision tree approach using agrochemical case examples with robust toxicity datasets can serve as a valuable tool to determine the endpoints and data streams (<i>in silico, in vitro, in vivo) </i>that provide critical data to support a study waiver approach.  Case examples using existing agrochemical toxicity datasets can also illustrate specific chemistry classes where dog toxicity data were used as the basis for a safety assessment and whether these effects operate through human relevant mechanisms.  Future opportunities to waive the required 90-day dog study should consider establishing guidance for a minimum dataset to support a waiver approach that is applicable for global regulatory submissions and to develop a framework where one can decide the need for toxicity testing in the dog both of which can reduce unnecessary use of this species for agrochemical toxicity testing while still providing a robust human health risk assessment.

Challenges and opportunities to waive the 90-day dog toxicity study for agrochemical human health risk assessments: Key elements from the 2021 CAAT workshop

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ACS Fall 2022

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