Revised Proposed Reference Exposure Levels for 1,3-butadiene

California’s Office of Environmental Health Hazard Assessment (OEHHA) is presenting a revised 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 2 April 2013. Revisions were made based on comments provided by the Scientific Review Panel at their meeting on 16 October 2012. OEHHA is required to develop guidelines for conducting health risk assessments under the Air Toxics Hot Spots Program [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][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 finalised 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 18 May 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, underwent review by the State’s Scientific Review Panel on Toxic Air Contaminants (Health and Safety Code section 39670 et seq.) on 16 October 2012. A copy of the revised draft is available at:

OEHHA, 1 March 2013 ; ;