Chromium, Trivalent Reference Exposure Levels - Technical Support Document
Chromium, Trivalent (Inorganic Water-Soluble Compounds)
The Office of Environmental Health Hazard Assessment (OEHHA) is adopting new Reference Exposure Levels (RELs) for Chromium, Trivalent (Inorganic Water-Soluble Compounds) (Cr(III)) for use in the Air Toxics Hot Spots Program. RELs are airborne concentrations of a chemical that are not anticipated to result in adverse noncancer health effects for specified exposure durations in the general population, including sensitive subpopulations. The adopted RELs cover different types of exposure to Cr(III) in air: infrequent 1-hour exposures, repeated 8-hour exposures, and continuous long-term exposure.
OEHHA is required to develop guidelines for conducting health risk assessments under the Air Toxics Hot Spots Program (Health and Safety Code Section 44360(b)(2)). In response to this statutory requirement, OEHHA develops RELs for many air pollutants, including Cr(III). The Cr(III) RELs were developed using the most recent “Air Toxics Hot Spots Program Technical Support Document for the Derivation of Noncancer Reference Exposure Levels” (OEHHA, 2008). The Cr(III) compounds will also be added to the list of Toxic Air Contaminants that may disproportionately impact children, pursuant to Health and Safety Code Section 39669.5(b)(1).
A draft document for the Cr(III) RELs was released on January 8, 2021 to solicit public comment and was discussed at a virtual public workshop during the subsequent 45-day public review period. The document was revised to reflect public comments, and peer reviewed by the State’s Scientific Review Panel on Toxic Air Contaminants (SRP) in May 2021 before being finalized. The Cr(III) REL values are as follows:
Acute REL (for infrequent 1–hour exposures): 0.48 micrograms Cr(III) per cubic meter (0.48 µg Cr(III)/m3)
Chronic REL (for long–term exposures): 0.06 μg Cr(III)/m3
8–Hour REL (for repeated 8–hour exposures): 0.12 μg Cr(III)/m3
Please direct any inquiries concerning technical matters or availability of the documents to:
Dr. John Budroe, Chief
Air Toxicology and Risk Assessment Section
Office of Environmental Health Hazard Assessment
1515 Clay Street, 16th Floor
Oakland, CA 94612
E–mail: john.budroe@oehha.ca.gov