This paper discusses various "philosophical" issues in standard setting in occupational and environmental health, i.e., general principles, actual procedures for standard setting, inter- and intra-agency discrepancies in procedures and criteria, and choices and decisions in the preparation of criteria documents and in the evaluation of the toxicology databases. Unpublished, possibly confidential information should be made available to expert committees, workers, and the general public. There is an urgent need to improve the validity of the toxicology databases that have to underpin occupational and environmental exposure limits. Standard setting requires various ethically loaded choices and decisions by experts, employees, managers, government officials, and politicians.