Policy reforms to update chemical safety testing

Toxicological evaluation of chemicals and newly emerging substances, such as engineered nanomaterials, is essential to protect human health and the environment (1). Traditional approaches for chemical safety assessment often use high-dose animal studies, human exposure estimates, linear dose extrapolations, and uncertainty factors to determine the circumstances under which human exposure is safe. But in 2016, major bipartisan reform of the antiquated Toxic Substances Control Act (TSCA) in the United States embraced a new paradigm emerging across the globe (2). This paradigm, relying largely on nonanimal, alternative testing strategies (ATS), uses mechanism-based in vitro assays and in silico predictive tools for testing chemicals at considerably less cost (3). We provide a cautious but hopeful assessment of this intersection of law and science. Although the law generally takes a sensible approach to using ATS for regulatory purposes, commitment by the U.S. Environmental Protection Agency (EPA) and its partner agencies remains the key to successful integration of ATS in TSCA.