Toxicity and Chemical Accidents

PAN Pesticide Database (Pesticide Action Network)

http://www.pesticideinfo.org/Index.html

The site contains the current toxicity and regulatory information for pesticides.

EXOTOXNET

http://extoxnet.orst.edu/index.html

EXTOXNET  deals with toxicology and environmental chemistry, and is a cooperative effort of University of California-Davis, Oregon State University,
Michigan State University, Cornell University, and the University of Idaho.
Primary files are maintained and archived at Oregon State University

This is a "Historical Incidents Search Page" -

http://www.incidentnews.gov/ 

Here are government reports concerning oil spill and chemical accidents. The site is maintained by National Ocean Service, National Oceanic and Atmospheric Administration. The reports are selective not comprehensive.