http://atsdr1.atsdr.cdc.gov:8080/
The Agency for Toxic Substances and Disease Registry identifies hazardous substances in the environment and their relation to adverse human health outcomes. Through education and outreach, the agency strives to prevent the causes from becoming effects. The home page contains searchable database structures for hazardous materials. Directories of Internet resources for environmental, materials, health and other government documents are provided. There's lots of interesting science and government information available here.