In this one-day course, participants will learn techniques for the meaningful interpretation of ecotoxicity data for regulatory purposes. The principal emphasis will be the ecotoxicity, fate, and transport of organic chemicals in the aquatic environment. Course topics include: basic environmental chemistry; hazard classification criteria; and procedures for estimating the physico-chemical, ecotoxicity, and fate properties of organic contaminants. Course format is lecture, group discussion, and individual exercises.