Proposed Revised Reference Exposure Levels for Benzene

The Office of Environmental Health Hazard Assessment (OEHHA) is presenting a draft document:  “Proposed Reference Exposure Levels (RELs) for benzene” for a second discussion by the Scientific Review Panel on Toxic Air Contaminants at its meeting on February 13, 2014 (see http://www.arb.ca.gov/srp/srpmeetings.htm for details and agenda).

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)]. OEHHA has developed Technical Support Documents (TSDs) in response to this statutory requirement, including the Technical Support Document for the Derivation of Noncancer Reference Exposure Levels, which was adopted in December 2008 and the Technical Support Document for Cancer Potency Factors, which was adopted in June 2009.

Proposed values for the acute, 8 hour, and chronic RELs are 27 µg/m3 (8 ppb), 3 µg/m3 (1 ppb) and 3 µg/m3 (1 ppb) respectively.  These were developed using the latest version of the non-cancer REL guidelines, including application of the revised methodology to protect infants, children and other sensitive subpopulations. When finalized and adopted, these RELs will be added to the compound-specific toxicity reviews and summary tables which appear as appendices to the Technical Support Document for the Derivation of Noncancer Reference Exposure Levels.

An earlier draft of the document describing the benzene RELs was presented on June 21, 2013 for public comment.  OEHHA reviewed the comments received, prepared responses, and revised the REL document where appropriate. The benzene REL document, along with the public comments and OEHHA’s response to these comments, were then peer reviewed by the State’s Scientific Review Panel (SRP) on Toxic Air Contaminants (Health and Safety Code section 39670 et seq.) on November 1, 2013.  The present document, being considered on February 13, 2014, is a revised version of the document discussed at the meeting held on November 1, 2013, reflecting changes based on comments of the SRP.

Please direct any inquiries concerning technical matters, availability of documents or comparison between these and previous versions to Dr. Daryn Dodge at (916) 445-9375 or daryn.dodge@oehha.ca.gov.