ATSDR: The Agency for Toxic Substances and Disease Registry, a part of the U.S. Department of Health and Human Services under the Public Health Service that works with states and other federal agencies to prevent exposure to hazardous substances from waste sites. The agency conducts public health assessments, health studies, surveillance activities, and health education training in communities around waste sites on the U.S. Environmental Protection Agency's National Priorities List. ATSDR also has developed toxicological profiles of hazardous chemicals found at these sites. Established: 1980. Headquarters: Atlanta, GA.