You can look up specific chemicals at these governmental agences:
ATSDR
ATSDR serves the public by 
using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and diseases related to toxic substances.
EPA Chemical Fact Sheets
EPA has developed information summaries on selected chemicals to describe how you might be exposed to these chemicals, how exposure to them might affect you and the environment, what happens to them in the environment, who regulates them, and whom to contact for additional information.
