Summary
The EPA IRIS chemical assessment for inorganic lead (CASRN 7439-92-1) is the US Environmental Protection Agency’s reference assessment for lead toxicity. EPA does not derive a quantitative oral reference dose (RfD) for lead; the RfD section of the IRIS file contains a qualitative discussion only, last revised 2004-07-08, on the basis that available data do not support a traditional threshold-based RfD derivation for the most sensitive (developmental neurotoxicity) endpoint. The carcinogenicity assessment was last revised 1988-09-26 and classifies inorganic lead as B2 (probable human carcinogen) based on animal evidence with inadequate human evidence; the cancer slope factor and unit risk are not derived. The structural similarity to the EPA IRIS cadmium situation (operative document is dated; quantitative reference values are pending or absent) is intentional methodological policy at EPA.
Key numbers
| Parameter | Value |
|---|---|
| CASRN | 7439-92-1 |
| Oral RfD (I.A.) | Not derived; qualitative discussion only, last revised 2004-07-08 |
| Inhalation RfC (I.B.) | Not evaluated |
| Carcinogenicity Assessment | Yes; last revised 1988-09-26 |
| Cancer classification | B2 (probable human carcinogen) |
| Cancer slope factor / unit risk | Not derived |
| File first on-line | 1988-03-01 |
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 4 sections added; narrative text revised |