Agency for Toxic Substances and Disease RegistryThe Agency for Toxic Substances and Disease Registry (ATSDR) is a federal, non-regulatory, environmental public health agency overseen by the U.S. Department of Health and Human Services. ATSDR is the lead federal public health agency for determining, preventing, and mitigating the human health effects of exposure to hazardous substances. ATSDR is the only federal health agency that works directly with concerned citizens to address environmental hazards and respond to requests for assistance from communities across the nation.