Chemicals Listed Effective August 1, 2008 as Known to the State of California to Cause Cancer or Reproductive Toxicity: gallium arsenide, hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide

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The Office of Environmental Health Hazard Assessment (OEHHA) of the California Environmental Protection Agency is adding gallium arsenide to the list of chemicals known to the state to cause cancer and hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide to the list of chemicals known to the state to cause reproductive toxicity for the purposes of Proposition 65. The listing of gallium arsenide, hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide is effective August 1, 2008.

Health and Safety Code section 25249.8(a) requires that certain substances identified by the International Agency for Research on Cancer (IARC) or the National Toxicology Program (NTP), as described in Labor Code section 6382(b)(1) and (d), be included on the Proposition 65 list as causing cancer. Labor Code section 6382(b)(1) references substances identified as human or animal carcinogens by IARC, and Labor Code section 6382(d) references substances identified as carcinogens or potential carcinogens by IARC or NTP.

Health and Safety Code section 25249.8(a) further requires that substances identified in Labor Code section 6382(d) as causing reproductive toxicity be included on the Proposition 65 list. Labor Code section 6382(d) captures any chemicals within the scope of the federal Hazard Communication Standard that are identified as reproductive toxicants. Chemicals fall within the scope of the Hazard Communication Standard if they are listed as hazardous in the latest edition of the American Conference of Governmental Industrial Hygienists (ACGIH) “Threshold Limit Values (TLVs).”

Pursuant to state law, IARC’s identification of gallium arsenide as carcinogenic to humans means that gallium arsenide must be included on the Proposition 65 list (Labor Code sections 6382(b)(1) and (d)). Also, ACGIH’s basing of the TLVs for hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide on reproductive toxicity means that these three chemicals must be included on the Proposition 65 list (Labor Code section 6382(d)).

The basis for the listing of gallium arsenide, hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide on the Proposition 65 list was described in OEHHA’s Request For Comments on Proposed Listing of Gallium Arsenide as Known to Cause Cancer and Hexafluoroacetone, Nitrous Oxide and Vinyl Cyclohexene Dioxide as Known to Cause Reproductive Toxicity published in the June 15, 2007, issue of the California Regulatory Notice Register (Register 2007, No. 24-Z). In 2006, IARC issued Volume 86 in its series IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. In this monograph, IARC concluded that gallium arsenide is carcinogenic to humans (Group 1). The TLVs for hexafluoroacetone (male endpoint), nitrous oxide (developmental endpoint) and vinyl cyclohexene dioxide (male and female endpoints) were assigned on the basis of ACGIH’s findings of reproductive effects.

OEHHA analyses of dose-response data to establish the no significant risk level (NSRL) for gallium arsenide or the maximum allowable dose levels (MADLs) for hexafluoroacetone, nitrous oxide and vinyl cyclohexene dioxide 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.

Cancer

Chemical Cas No. Toxicological Endpoint Listing Mechanism1
Gallium arsenide 1303-00-0 Cancer

LC

Reproductive toxicity

Chemical

CAS No. Toxicological Endpoint Listing Mechanism1
Hexafluoroacetone 684-16-2 Male reproductive toxicity LC
Nitrous oxide 10024-97-2 Developmental toxicity LC
Vinyl cyclohexene dioxide2 106-87-6 Female and male reproductive toxicity LC

Footnotes and References

1 Listing mechanism:
LC – “Labor Code” mechanism (Labor Code sections 6382(b)(1) and (d))

2 The chemical was previously listed under the synonym name of 4-vinyl-1-cyclohexene diepoxide as a chemical known to cause cancer on July 1, 1990.