DOD needs to understand the relative threat of the increasingly long list of registered chemical substances, particularly in terms of potential acute hazard. To help DOD achieve its goal to protect its deployed personnel, this study will consider modern approaches for predicting toxicity and suggest an overall conceptual approach for using such information to evaluate acute hazards. The committee will consider the information provided by predictive-toxicology approaches that is increasingly being generated and used in the environmental health and pharmaceutical sectors to enhance or replace information from traditional, empirical testing of chemical safety in animals.