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News Release USDL: 95-515
Monday, December 11, 1995
CONTACT: Frank Kane, (202) 219-8151

The Occupational Safety and Health Administration (OSHA) announced it is extending until Dec. 29 its reopening of the record on its proposed standard for methylene chloride (MC), a probable human carcinogen widely used as an industrial solvent.

The proposed rule would reduce the permissible worker exposure limit from the current 500 parts of MC per million parts of air (500 ppm) to 25 ppm, averaged over eight hours. Ancillary measures such as employee training and medical surveillance also would be required. OSHA has estimated that the proposed rule would reduce cancer risk by 95 percent for more than 185,000 workers.

OSHA's proposed MC risk assessment for cancer was based primarily on extrapolation from mouse cancer bioassay data. Considerable data are already available regarding this issue in the rulemaking record.

On Oct. 24 OSHA reopened the rulemaking for 30 days with comments limited to the subject of recently conducted studies submitted by the Halogenated Solvents Industry Alliance (HSIA) which assert that species differences in the enzymatic metabolism of MC make the mouse a poor surrogate for estimating human cancer risk. The use of the mouse data is a critical issue in the MC rulemaking. The agency reopened the record to incorporate these studies and to give the public an opportunity to comment on their validity and on the appropriateness of the conclusions drawn by HSIA.

The Oct. 24 notice generated substantial interest and the agency is concerned that the initial 30 days was insufficient to allow full participation by interested parties. Accordingly, OSHA is reopening the comment period until Dec. 29, 1995.

Requests for copies of the HSIA studies should be addressed to Christine Whittaker, Room N-3718, Health Standards Programs, OSHA, U.S. Department of Labor, 200 Constitution Ave. NW, Washington, DC 20210. Telephone: (202) 219-7174. Fax: (202) 219-7125.

Written comments on the studies must be postmarked by Dec. 29, 1995, and submitted in quadruplicate to the OSHA Docket Office, Docket No. H-071B, U.S. Department of Labor, Room N-2625, 200 Constitution Ave., NW, Washington, DC 20210. Phone: (202) 219-7894. All materials submitted will be available for inspection and copying in the docket office. Materials previously submitted to the docket for the rulemaking do not have to be resubmitted.

Notice of the reopening appeared in the Dec. 6, 1995, Federal Register.