The Toxicology Data Network (TOXNET), was a suite of U.S. National Library of Medicine databases that focus on hazardous chemcials, toxicology, and their effects on the environment. Check the archived information.
Chemical database is a dictionary of over 400,000 chemicals (names, synonyms, and structures). ChemIDplus includes links to NLM and other databases and resources, including links to federal, state and international agencies. ChemIDplus Lite is designed for simple searching on name or registry. ChemIDplus Advanced helps users draw their own structures and perform similarity and substructure searches. (From https://chem.nlm.nih.gov/chemidplus/chemidlite.jsp)
HSDB is a toxicology database that focuses on the toxicology of potentially hazardous chemicals. It provides information on human exposure, industrial hygiene, emergency handling procedures, environmental fate, regulatory requirements, nanomaterials, and related areas. The information in HSDB has been assessed by a Scientific Review Panel.
Note that HSDB has been subsumed by PubChem.
HSB may be searched by chemical name or synonym or CAS number.
Toxicology Literature Online (TOXLINE)
TOXLINE is a bibliographic database with an assortment of citations from specialized journals and other sources. It provides references covering the biochemical, pharmacological, physiological, and toxicological effects of drugs and other chemicals. Most of TOXLINE's bibliographic citations contain abstracts and/or indexing terms and Chemical Abstract Service (CAS) Registry Numbers.(From https://toxnet.nlm.nih.gov/newtoxnet/toxline.htm)
Toxline is now a part of PubMed.