Chemicals Listed Effective June 11, 2004 as Known to the State of California to Cause Cancer: Five Chemicals

Jun 11, 2004

Chemicals Listed Effective June 11, 2004 as Known to the State of California to Cause Cancer: 3,3'-dimethoxybenzidine-based dyes metabolized to 3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine-based dyes metabolized to 3,3'-dimethylbenzidine, ethylbenzene, propylene glycol mono-t-butyl ether, and thiouracil

The Office of Environmental Health Hazard Assessment (OEHHA) of the California Environmental Protection Agency is adding 3,3'-dimethoxybenzidine-based dyes metabolized to 3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine-based dyes metabolized to 3,3'-dimethylbenzidine, ethylbenzene, propylene glycol mono-t-butyl ether, and thiouracil to the list of chemicals known to the state to cause cancer for purposes of the Safe Drinking Water and Toxic Enforcement Act of 1986 (Health and Safety Code section 25249.5 et seq., Proposition 65). The listing of these chemicals is effective June 11, 2004.

3,3'-dimethoxybenzidine-based dyes metabolized to 3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine-based dyes metabolized to 3,3'-dimethylbenzidine, ethylbenzene (CAS No. 100-41-4), propylene glycol mono-t-butyl ether (CAS No. 57018-52-7), and thiouracil (CAS No. 141-90-2) are listed as chemicals known to the State of California to cause cancer. The listing of these chemicals is based on a formal identification by authoritative bodies (i.e., the National Toxicology Program [“NTP”] and the International Agency for Research on Cancer [“IARC”] that these chemicals cause cancer. Regulations governing the listing of chemicals under the “authoritative bodies” mechanism are published in Title 22, Cal. Code of Regs. section 12306.

The reader is directed to the Notice of Intent to List 3,3'-dimethoxybenzidine-based dyes metabolized to 3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine-based dyes metabolized to 3,3'-dimethylbenzidine, ethylbenzene, propylene glycol mono-t-butyl ether, and thiouracil published in the April 9, 2004, issue of the California Regulatory Notice Register (Register No. 2004, No. 15-Z) for the documentation supporting OEHHA’s determination that the criteria for administrative listing have been satisfied for these chemicals. The documentation was developed to explain the basis for listing these chemicals via the authoritative bodies provision of Proposition 65. OEHHA analyses of dose-response data to establish the no significant risk levels (NSRLs) for these chemicals 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 /proposition-65.

A complete, updated Proposition 65 list is published elsewhere in this issue of the California Regulatory Notice Register. The following table outlines the addition of these chemicals to the Proposition 65 chemical list as known to the State to cause cancer:

Chemicals listed June 11, 2004 as known to cause cancer:

Chemical	CAS No.	Toxicological Endpoint	Listing Mechanism ¹
3,3'-Dimethoxybenzidine-based dyes metabolized to 3,3'-dimethoxybenzidine	---	Cancer	AB
3,3'-Dimethylbenzidine-based dyes metabolized to 3,3'-dimethylbenzidine	---1	Cancer	AB
Ethylbenzene	100-41-4	Cancer	AB
Propylene glycol mono- t -butyl ether	57018-52-7	Cancer	AB
Thiouracil	141-90-2	Cancer	AB