National Library of Medicine has released an updated Tox Town Website https://toxtown.nlm.nih.gov/
Toxicology e-books - Encyclopedia of Toxicology
RTECS: Registry of toxic effects of chemical substances. National Institute for Occupational Safety and Health. URL: http://www.cdc.gov/niosh/rtecs/
NIOSH Pocket Guide to Chemical Hazards: National Institute for Occupational Safety and Health (NIOSH) Education and Information Division. URL: http://www.cdc.gov/niosh/npg/
Toxic Substances Portal: ATSDR: Agency for Toxic Substances & Disease Registry URL: http://www.atsdr.cdc.gov/substances/index.asp
TOXNET: toxicology data network: U.S. National Library of Medicine. URL: http://toxnet.nlm.nih.gov/