News Release USDL: 95-433
Tuesday, October 24, 1995
Contact: Deborah Page Crawford, (202) 219-8151
OSHA Announces 30-Day Limited Re-opening Of Methylene Chloride
The U.S. Department of Labor's Occupational Safety and Health Administration (OSHA)
today reopened the rulemaking record until Nov. 24 on its proposed standard for methylene
chloride (MC), a probable human carcinogen widely used as an industrial
The proposed rule would reduce the permissible worker exposure to the chemical 20-fold,
from the current 500 parts of MC per million parts of air (500 pm) to 25 pm, averaged over eight
hours. OSHA has estimated that the proposed rule would reduce cancer risk by 95 percent for
more than 186,000 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.
OSHA is limiting the reopening for comments on 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 in assessing human risk is a critical issue in the MC rulemaking.
The agency is reopening the record to incorporate these studies and to provide the public with an
opportunity to comment on their validity and on the appropriateness of the conclusions drawn by
Interested parties can obtain copies of the newly incorporated materials upon request to
facilitate full and timely public participation. Requests for copies should be addressed to
Christine Whittaker, Room N3718, Health Standards Programs, OSHA, U.S. Department of
Labor, 200 Constitution Ave., N.W., Washington, D.C. 20210; telephone: (202) 219-7174; fax:
Written comments on the above materials incorporated into the rulemaking record must
be postmarked by Nov. 24, 1995, and submitted in quadruplicate to the OSHA Docket Office,
Docket No. H-071B, Room N2625, 200 Constitution Ave., N.W., Washington, D.C. 20210;
telephone: (202) 219-7894.
Notice of the reopening of the rulemaking record for MC is scheduled to be published in
the October 24 Federal Register.