Revised Proposed Reference Exposure Levels for 1,3-Butadiene

Sep 11, 2012

The Office of Environmental Health Hazard Assessment (OEHHA) is presenting a draft document: “Proposed Reference Exposure Levels (RELs) for 1,3-butadiene” for discussion by the Scientific Review Panel on Toxic Air Contaminants at its meeting on October 16, 2012 at the Cal/EPA building in Sacramento (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 0.66 mg/m³ (297 ppb), 28 µg/m³ (13 ppb) and 7 µg/m³ (3 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 butadiene RELs was presented on May 18, 2012 for public comment, and OEHHA has reviewed the comments received and prepared responses, as well as revising the REL document where appropriate. The 1,3-butadiene REL document, along with the public comments and OEHHA’s response to these comments, will now undergo review by the State’s Scientific Review Panel on Toxic Air Contaminants (Health and Safety Code section 39670 et seq.).

Please direct any inquiries concerning technical matters, availability of documents or comparison between these and previous versions to:

Dr. John Budroe
Chief, Air Toxicology and Risk Assessment Section
Air, Community, and Environmental Research Branch
Office of Environmental Health Hazard Assessment
1515 Clay Street, 16th Floor
Oakland, CA, 94612

E–mail: John.Budroe@oehha.ca.gov

Telephone: (510) 622-3145