Toxicology database guide: HSDB, CompTox, ECOTOX and ATSDR

Which toxicology database to use, and what each one is good for

Choose a toxicology database by the evidence you need: HSDB in PubChem for legacy hazard excerpts, the EPA CompTox Chemicals Dashboard for linked chemical and hazard data, ToxCast for in vitro screening, ECOTOX for environmental effects, and ATSDR Toxicological Profiles for substance-level health evaluations. RTECS is licensed, so check institutional access before you treat it as a free government search. Read any result next to the source study, the exposure and the classification rules that apply to your product.

The main toxicology databases compared

Where the old HSDB and TOXNET records went

The Hazardous Substances Data Bank didn't disappear. NLM retired TOXNET on December 16, 2019 and moved HSDB into PubChem. NLM's TOXNET page, last reviewed on August 9, 2024, still lists HSDB in PubChem.

NLM's instructions say HSDB content is spread across PubChem sections. To isolate it, open Information Sources, use FILTER BY SOURCE and select HSDB. That page was last reviewed on September 24, 2019, so the layout may have moved since. Provenance still shows in the data: the PubChem data record for hydrogen cyanide carries references labelled Hazardous Substances Data Bank (HSDB), with a link back to the HSDB record.

HSDB excerpts are preserved in PubChem but are not necessarily updated. Before you quote a summary in an assessment, check its provenance and the cited study's publication date.

CompTox Dashboard and ToxCast are different things

The CompTox Chemicals Dashboard is EPA's search interface. You can search by chemical identifier, product category or assay and gene, and run batch searches. EPA states: "The data are not reviewed by USEPA - the user must apply judgment in use of the information." EPA also asks users to consult the original sources where possible. So a value on the Dashboard is a lead to trace, not an EPA-endorsed number.

Identity is handled by DSSTox, which links chemical structures to source-substance identifiers. Use it to check identity, but compare the structure yourself, because identifier matches can be wrong.

EPA's release notes list Dashboard version 2.9.0 on October 15, 2026. A software release date does not establish when the underlying studies were updated.

ToxCast is a screening programme. The Dashboard is one way to open its data, not a second copy of the dataset. ToxCast covers public in vitro medium- and high-throughput assay data, processed into invitrodb, and EPA describes uses that include prioritisation and hazard characterisation. CTX APIs and bulk downloads are the other routes. A screening result is a bioactivity signal. It isn't proof of adverse effects in people at real exposures, and it isn't a classification or a safe-use conclusion.

ECOTOX for environmental toxicity

The ECOTOX Knowledgebase holds single-chemical toxicity data for aquatic and terrestrial species. It's the ecological effects resource in this list, not a human health database. EPA's ECOTOX page says the primary source is peer-reviewed literature, the knowledgebase is updated quarterly, and the data inform ecological risk assessments.

The ECOTOX app warns that new literature can take six months or longer to appear. For a current assessment, supplement database results with a literature search. ECOTOX documentation describes using chemical names, synonyms and CAS numbers in its literature searching. When you compare results, keep the species, test duration, endpoint, units and original reference together. Do not treat LC50 values as comparable without checking the species and exposure duration.

ATSDR Toxicological Profiles and ToxFAQs

The Agency for Toxic Substances and Disease Registry publishes Toxicological Profiles, each a peer-reviewed compilation of toxicity data on one hazardous substance. They cover selected substances, tied to substances found at National Priorities List sites, not every chemical on the market.

ATSDR also publishes Minimal Risk Levels. An MRL estimates the daily exposure likely to carry no appreciable risk of non-cancer adverse effects over a set duration. ATSDR calls it a screening tool. It's not an occupational exposure limit, a cancer threshold or a guarantee of safety.

For a quick read, use ToxFAQs. ATSDR describes them as "summaries about hazardous substances" excerpted from the Toxicological Profiles. Use a ToxFAQ for orientation and the full profile for detailed evaluation.

RTECS needs a licence

The Registry of Toxic Effects of Chemical Substances compiles data extracted from open scientific literature. Free TOXNET access to RTECS ended on November 13, 1998, and on December 18, 2001 NIOSH completed a non-exclusive licensing agreement that handed updating, licensing, marketing and distribution to a private organisation.

That NIOSH page was last reviewed in 2016. Do not rely on it to identify today's distributor. Ask your library or information team whether your organisation has access before you plan around it. Lists of "free toxicology databases" that include RTECS are out of date.

A simple search workflow

1. Fix the identity first. Use CAS number, name and structure, and check salts, hydrates and isomers separately, because they can carry different data.
2. Decide the endpoint. For human health, start with HSDB, CompTox or ATSDR, and use ToxCast only as a screen. Environmental effects point you to ECOTOX.
3. Trace every value to its original study. Note the study date, not just the database update date.
4. Interpret it against exposure. A screening hit, an LC50 and an MRL each answer a different question.
5. Check the legal position separately: the classification list that applies to your market and your supplier's safety data sheet.

Lists of hazardous and toxic chemicals

A chemical list, a list of toxic chemicals or a chemical hazard list only covers the law that created it. No single list of hazardous chemicals satisfies every US and GB duty.

In the US, EPA's Consolidated List of Lists gathers chemicals covered by reporting and release programmes such as EPCRA and CERCLA. EPA calls it "a reference tool, not a definitive source of compliance information." It isn't a list of every hazardous chemical either. The US Hazard Communication Standard separately sets hazard-evaluation and safety-data-sheet duties for manufacturers and importers. Check its scope and exceptions for your product.

In Great Britain, HSE runs the GB mandatory classification list, and those entries can differ from EU harmonised classifications. Mixtures and substances without a mandatory entry still need self-classification, as do hazard classes an existing entry doesn't cover. So a substance missing from the GB list isn't free of hazard.

Database summaries also don't replace the supplier's SDS. HSE says suppliers must provide an up-to-date safety data sheet for substances dangerous for supply, and adds that "A safety data sheet is not a risk assessment."

RegAffairs AI has a public answer on which toxicology databases to use for this question, with links to the sources behind it.