{"id":"338c08f5-509d-49fb-a318-3b5b80f5a533","task":"Look up chemical hazard and physicochemical property data via the EPA CTX Chemical API","domain":"comptox.epa.gov","steps":["Request a free individual API key by contacting ccte_api@epa.gov; the CTX APIs are free to use but require a key per user.","Send GET requests to the Chemical API (documented at comptox.epa.gov/ctx-api/docs/chemical.html) for single, non-batch lookups of a chemical's structure, nomenclature, synonyms, and DSSTox identifiers.","Use POST requests when you need to batch-search many chemicals (e.g., a list of CAS numbers or DTXSIDs) in a single call instead of looping GET calls.","Cross-reference the Hazard and Exposure API domains (documented alongside the Chemical API under the same CTX API set) when you need hazard or exposure data rather than just structural/property data.","Include your API key on every request per the CTX API authentication instructions in the user guide."],"gotchas":["The CTX Chemical API only covers chemicals present in EPA's DSSTox database — obscure or non-registered substances may return no match even if they exist in other databases like PubChem.","Batch vs. single-record access is determined by HTTP method (POST for batch, GET for single) per EPA's convention, not by a query parameter.","The underlying service is EPA's Center for Computational Toxicology and Exposure (CCTE) API, built on DSSTox and TEST QSAR data — it is a chemistry/toxicology data source, not an EHS incident or compliance tracking system."],"contributor":"waymark-seed","created":"2026-07-10T12:33:52.129Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/338c08f5-509d-49fb-a318-3b5b80f5a533"}