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The Office of Environmental Health Hazard Assessment (OEHHA) of the California Environmental Protection Agency is adding 1,3-butadiene to the list of chemicals known to the State to cause reproductive toxicity for purposes of the Safe Drinking Water and Toxic Enforcement Act of 1986 (commonly known as Proposition 65, Health and Safety Code section 25249.5 et seq.). The listing of 1,3-butadiene is effective April 16, 2004.

1,3-Butadiene (CAS No. 106-99-0) is listed as a chemical known to the State of California to cause reproductive toxicity for developmental, female reproductive and male reproductive toxicity endpoints. The listing of 1,3-butadiene is based on a formal identification by authoritative bodies (i.e., the National Institute for Occupational Safety and Health [“NIOSH”] and the U.S. Environmental Protection Agency [“US EPA”]) that this chemical causes reproductive toxicity. Regulations governing the listing of chemicals under the “authoritative bodies” mechanism are published in Title 22, California Code of Regulations, section 12306.

The reader is directed to the Notice of Intent to List 1,3-butadiene published in the October 31, 2003, issue of the California Regulatory Notice Register (Register 2003, No. 44-Z) for the documentation supporting OEHHA’s determination that the criteria for administrative listing have been satisfied for this chemical. The documentation was developed to explain the basis for listing 1,3-butadiene via the authoritative bodies provision of Proposition 65. OEHHA analyses of dose response data to establish a maximum allowable dose level (MADL) for 1,3-butadiene under Proposition 65 have not been conducted. The priority status of the development of such analyses will be announced in a future OEHHA Proposition 65 Status Report for Safe Harbor Levels, available at http://www.oehha.ca.gov/prop65.html.

A complete, updated Proposition 65 chemical list is published elsewhere in this issue of the California Regulatory Notice Register. The following table outlines the addition of 1,3-butadiene to the Proposition 65 chemical list as known to the State to cause reproductive toxicity:

¹ Listing mechanism:
AB – “authoritative body” mechanism (Title 22, California Code of Regulations, section 12306)

Follow this link to download a copy of this notice as a pdf file.

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For questions regarding Proposition 65, please contact the Cynthia Oshita in the Proposition 65 Implementation Program

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