Draft IRIS CrVI Toxicology Review

In the October 19, 2022 Federal Register the Environmental Protection Agency (EPA) announced the availability of a draft “Integrated Risk Information System (IRIS) Toxicological Review of Hexavalent Chromium.” The draft toxicology review is out for a 60-day public period for public comment and review (public comments are due by December 19, 2022). After the public review and comment period, EPA will present the draft toxicology review to the Science Advisory Board for their review. The draft IRIS document reviews information on inhalation and ingestion routes of exposure for both cancer and non-cancer health effects.

The draft toxicology review is a fairly large document, and several supplement documents posted by EPA are also large. The link below should take you directly to the EPA’s downloads section for the draft IRIS CrVI toxicology review:

Text copied from the draft IRIS Executive Summary:
“For cancer via the oral route of exposure, Cr(VI) is likely to be carcinogenic to the human GI tract. Because a mutagenic mode-of-action (MOA) for Cr(VI) carcinogenicity is “sufficiently supported in (laboratory) animals” and “relevant to humans,” EPA used a linear low dose extrapolation…….The total lifetime [cancer] oral slope factor (OSF) for Cr(VI) is 0.5 (per mg/kg-d).”