A twin transition in regulatory toxicology: moving toward Chemicals 2.0 and phasing out animal testing.

The European regulatory framework on chemicals is at a crossroads. There are calls for the framework to be more effective, by better protecting people and the environment. There is also room for it to be more efficient and cost-effective, by harmonizing assessment practices across sectors and avoiding the need for unnecessary testing. At the same time, there is a political commitment to phase out animal testing in chemical safety assessments. In this commentary, we argue that these needs are not at odds with each other. On the contrary, the European Commission's roadmap to phase out animal testing could also be the transition pathway to a more efficient, effective, and sustainable regulatory ecosystem. Central to our proposal is a framework based on biological reasoning in which biological questions can be answered by a choice of methods, with non-animal methods progressively becoming the only choice. Within this framework, a tiered approach to testing and assessment allows for greater efficiency and effectiveness, while also introducing considerations of proportionality and cost-effectiveness. Testing strategies, and their component methods, should be developed in tandem and judged in terms of their outcomes, and the protection levels they inform, rather than their ability to predict the outputs of animal tests.