Notice of Adoption of Reference Exposure Levels for Toluene

Download Reference Exposure Levels for Toluene

The Office of Environmental Health Hazard Assessment (OEHHA) is adopting new Reference Exposure Levels (RELs) for Toluene 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 toluene in air: infrequent 1-hour exposures, repeated 8-hour exposures, and continuous long-term exposures.

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 Toluene. The Toluene 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). Toluene has been demonstrated to have neurotoxic effects.  Children may be more sensitive to Toluene neurotoxicity than adults because of the sensitivity of their developing nervous systems to neurotoxicants.  Therefore, this chemical 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 Toluene RELs was released by OEHHA on December 1, 2017, to solicit public comment and was discussed at OEHHA-conducted public workshops in Sacramento and Diamond Bar, CA during the subsequent 75-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 June 2019, before being finalized.

The REL values are as follows:

Acute REL (for a 1–hour exposure):  5,000 micrograms per cubic meter (µg/m3)
8–Hour REL (for repeated 8–hour exposures):  830 µg/m3
Chronic REL (for long–term exposures):  420 µg/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