Abstract:Regulatory toxicology has emerged as a necessary discipline to ensure chemicals introduced into commerce are safe. The New Chemicals program is a regulatory toxicology program required under the Toxic Substances Control Act (TSCA) where the US Environmental Protection Agency (EPA) evaluates new or significant new uses of existing chemicals. Submitters are not required to include human or environmental effects data, or undertake toxicity testing and so constrain the EPA and the basic data available to make informed decisions. We therefore sought to determine the methodology used by this program to inform regulatory, consent order decisions. We found that the EPA applied analogue analyses, or in silico methods to inform two-thirds of the decisions evaluated. No new tests were carried out. This study's findings are important for other regulators in the potential adoption of alternative testing methods to inform regulatory decisions going forward.Keywords: TSCA new chemicals program; alternative test methods; tiered testing strategy.Reference to this paper should be made as follows: Borotkanics, R. and Locke, P. (2017) 'EPAs methodology to inform TSCA pre-manufacturing notification decision-making: a critical analysis based on chemicals regulated by consent order', Int.