A collection of toxicology and environmental health databases managed by the U.S. National Library of Medicine (NLM), a division of the National Institutes of Health (NIH). TOXNET provides free access to a range of databases covering toxicology, hazardous chemicals, environmental health, and related fields. 

Used by health professionals, researchers, emergency responders, and the general public with focus areas on human and animal toxicity, hazardous chemical data, risk assessment, environmental, and occupational health.

TOXNET has moved and as part of the broader NLM reorganization, most of the toxicology information services have been integrated into other NLM services. TOXNET has retired but you can find the services it provided with these databases: 

• PubChem, for comprehensive toxicology information.
• Drugs and Lactation Database (LactMed), for information on drugs and other chemicals that breastfeeding mothers may be exposed to.
• DailyMed, the official source for FDA-approved drug labeling in the U.S. Use for medication indications and usages, dosage and administration information, contraindications, warnings and precautions, adverse reactions, drug interactions, and more. 
• MedlinePlus Drugs, Herbs and Supplements database, a trustworthy source of consumer-focused drug information.
• LiverTox, provides up-to-date information on the diagnosis, cause, frequency, clinical patterns and management of liver injury due to prescription and nonprescription medications, selected herbal and dietary supplements.
• CTD, Comparative Toxicogenomics Database, identifies interactions between chemicals and genes to understand how environmental chemicals impact human health.
• Consumer Product Information Database- What's in it? provides detailed information about the chemical ingredients in common consumer products. Designed to help consumer, researchers, health professionals, and regulators understand what's in everyday items and assess potential health and environmental risks. Use it to look up product in your home to see what chemicals they contain.
• HazMap, gives information on hazardous chemicals and occupational diseases.
• Dietary Supplement Label Database, includes current and historical label information from products marketed in the U.S.
• Dietary Supplement Ingredient Database, provides estimated levels of ingredients in dietary supplement products.
• Integrated Risk Information System, a program that evaluates information on health effects that may result from exposure to environmental contaminates. 
• Chemical Carcinogenesis Research Information System, shares curated, peer-reviewed data on the carcinogenicity, mutagenicity, tumor promotion, and tumor inhibition properties of chemical substances.
• Carcinogenic Potency Database, scientific resource that compiles and standardizes results from long-term animal cancer tests on various chemical substances.

For chemical releases & mapping resources, use:

• National Pollutant Release Inventory, Canada's public inventory of releases, disposals, and transfers of pollutants.
• Census.gov, as an original source of data used in TOXNET
• US EPA Clean Air Markets Program, track and report air quality, health, and environmental conditions.
• EPA Geospatial Applications, reports on air and water quality, has an interactive map to show excess food opportunities, tracks Superfund cleanups throughout the country, and has a tool that facilitates environmental review process and project planning in relation to environmental conditions.
• Facility Registry Service, a centralized database maintained by the EPA, stores and manages information about facilities, sites, or places that are subject to environmental regulations and environmental interests across EPA programs.
• US EPA Superfund Program, a federal government initiative aimed at cleaning up the nation's most contaminated land and responding to environmental emergencies, oil spills, and natural disasters.
• US EPA Toxics Release Program, tracks the management of certain toxic chemicals that may pose a threat to human health and the environment.
• US NIH NCI Surveillance, Epidemiology, and End Results Program (SEER), an authoritative source for cancer statistics in the U.S.