Regulatory bodies worldwide are charged with making major decisions related to chemical toxicology, such as designation of toxic thresholds and establishment of criteria for preclinical testing and toxic hazard classification. Although every agency has access to the same research data, each agency uses different criteria for judging which data to consider in setting policy and how best to interpret and apply those data. Recent international differences in legislation regarding bisphenol A and recombinant bovine somatotropin highlight the diverse routes taken in the regulatory decision-making process ; at the same time, tensions between the exigencies of protecting public health on the one hand and safeguarding commercial interests on the other are revealed in the debate over the precautionary principle. Although expert analysis of scientific evidence will always serve as the guiding principle for sound regulatory action, political, economic, and even sociocultural interests also play a role in policy.