• Publication Date:
  • Publication Type:
    Proposed Rule
  • Fed Register #:
  • Title:
    Occupational Exposure to Methylene Chloride


Occupational Safety and Health Administration

29 CFR Parts 1910, 1915 and 1926

[Docket No. H-071A]

Occupational Exposure to Methylene Chloride

AGENCY: Occupational Safety and Health Administration (OSHA), Department of Labor.

ACTION: Proposed rule; limited reopening of the rulemaking record.

SUMMARY: The Occupational Safety and Health Administration (OSHA) is reopening the record for the proposed revision (NPRM) of the regulation of methylene chloride (MC) (56 FR 57036, November 7, 1991) to incorporate (1) information regarding engineering controls for MC exposure in the furniture stripping industry; (2) a National Cancer Institute study of occupational exposure to chlorinated aliphatic hydrocarbons and the risk of astrocytic brain cancer; and (3) information regarding the use of MC as a solvent in adhesive formulations in flexible foam manufacturing. The NPRM and hearing notice (57 FR 24438, June 9, 1992) raised concerns and solicited information regarding the ability of furniture stripping operations to comply with the proposed PELs through the use of engineering controls; human cancer risk from exposure to MC; and any applications of MC not addressed by OSHA's Preliminary Regulatory Impact Assessment. The Agency generated a considerable amount of information regarding these and other MC-related issues at public hearings (September 16-24, 1992 and October 14-16, 1992) and in post-hearing comment periods that ended on March 15, 1993. OSHA subsequently received the materials covered by this notice.

OSHA has determined that the above-mentioned information is relevant to full consideration of issues raised by the MC rulemaking. Therefore, OSHA is reopening the record to incorporate the pertinent materials and to allow the public an opportunity to comment.

DATES: Written comments on the materials incorporated through the notice of reopening must be postmarked by April 25, 1994.

ADDRESSES: Comments are to be submitted in quadruplicate to the Docket Office, Docket No. H-071A, U.S. Department of Labor, room N-2634, 200 Constitution Avenue, NW., Washington, DC 20210. Telephone (202) 219-7894. Written comments limited to 10 pages or less in length also may be transmitted by facsimile to (202) 219-5046, provided that the original and three copies are sent to the Docket Office thereafter.

FOR FURTHER INFORMATION CONTACT: Mr. James F. Foster, Occupational Safety and Health Administration, U.S. Department of Labor, room N-3647, 200 Constitution Avenue, NW., Washington, DC 20210. Telephone (202) 219-8148.


I. Background

On November 7, 1991, OSHA issued a notice of proposed rulemaking (NPRM) (56 FR 57036) to address the significant risks of MC-induced health effects. The proposed rule required employers to reduce occupational exposure to MC and to institute ancillary measures, such as employee training and medical surveillance, for further protection of MC-exposed workers.

OSHA convened public hearings in Washington, DC on September 16-24, 1992 and in San Francisco, CA on October 14-16, 1992. The post-hearing period for the submission of additional briefs, arguments and summations ended on March 15, 1993.

The Agency has subsequently obtained information which OSHA believes should be considered in the drafting of the final rule. Accordingly, the Agency is reopening the rulemaking record so the public has an opportunity to comment on that information. The materials being added to the record are discussed below.

A. Feasibility Analysis for the Furniture Stripping Sector

OSHA conducted a Preliminary Regulatory Impact Analysis and preliminarily determined that it would be feasible for the furniture stripping sector to comply with the proposed standard of 25 ppm as an 8-hour time-weighted average (TWA) permissible exposure limit (PEL) with a 125 ppm short-term exposure limit (as measured over 15 minutes) (STEL) and ancillary provisions (e.g., exposure monitoring, medical surveillance and training). Several commenters and hearing participants questioned the feasibility determination (Exs. 29, 30, 73 and 86). In response to issues raised during the hearings and comment periods, OSHA contracted with Mr. Richard Green to reexamine the technical and economic feasibility of the proposed rule for the furniture stripping industry. In order to give interested parties an opportunity to comment on this analysis, it is being introduced into the rulemaking record at this time.

Mr. Green determined that the proposed standard would be technically and economically feasible for furniture refinishers. The cost of engineering controls and additional heating (of make-up air) needed to comply with the proposed rule were estimated to be approximately $300 per establishment per year. Total compliance costs would be higher than this figure and include costs for ancillary provisions, such as exposure monitoring, medical surveillance and training.

Mr. Green determined the amount of ventilation that would be needed based upon the rate of evaporation of methylene chloride, principles of dilution ventilation, and estimates of costs for heating make-up air. Mr. Green's analysis utilized data in the MC docket and general reference materials such as the ACGIH Industrial Ventilation Manual for ventilation recommendations, and the 1993 Statistical Abstract of the United States to obtain monthly average, high and low temperatures.

Based on theoretical and empirical models, Mr. Green determined that the average-sized firm will need to install an approximately 5,000 cubic feet per minute (cfm) fan in both the stripping and rinse areas to ensure that the proposed PEL could be met in both areas. This would ensure good air mixing in both areas and provide adequate ventilation capacity. Mr. Green also recommended that the fans should be located near each process to provide a local spot ventilation effect.

OSHA solicits comments on Mr. Green's analysis and the appropriateness of using this analysis as a basis for the Agency's final determination of feasibility in the furniture stripping sector.

B. National Cancer Institute Study on Methylene Chloride Exposure and the Risk of Developing Astrocytic Brain Cancer

After the post-hearing comment period closed, OSHA received a copy of a study on the risk of developing brain cancer after exposure to chlorinated solvents conducted by researchers at the National Cancer Institute. This study was accepted for publication as two journal articles to be published in the American Journal of Industrial Medicine as "Occupational exposure to chlorinated aliphatic hydrocarbons and risk of astrocytic brain cancer" by Ellen F. Heineman et al. and "Occupational exposure to chlorinated aliphatic hydrocarbons: job exposure matrix" by M.R. Gomez et al.

The abstract for the Heineman et al. paper reads as follows, Chlorinated aliphatic hydrocarbons (CAHs) were evaluated as potential risk factors for astrocytic brain tumors. Job-exposure matrices for six individual CAHs and for the general class of organic solvents were applied to data from a case-control study of brain cancer among white men. The matrices indicated whether the CAHs were likely to have been used in each industry and occupation by decade (1920-1980), and provided estimates of probability and intensity of exposure for "exposed" industries and occupations. Cumulative exposure indices were calculated for each subject.

Associations of astrocytic brain cancer were observed with likely exposure to carbon tetrachloride, methylene chloride, tetrachloroethylene, and trichloroethylene, but were strongest for methylene chloride. Exposure to chloroform or methychloroform showed little indication of an association with brain cancer. Risk of astrocytic brain tumors increased with probability and average intensity of exposure, and with duration of employment in jobs considered exposed to methylene chloride, but not with a cumulative exposure score. These trends could not be explained by exposures to the other solvents.

The Gomez et al. paper explains in detail the job-exposure matrix used to determine whether exposure to a particular solvent was likely for the subjects of the study. OSHA solicits comments on this study and its implications for the MC risk assessment.

C. Information Regarding the Use of Methylene Chloride as a Solvent in Adhesive Formulations in Flexible Foam Manufacturing

During the rulemaking proceedings, OSHA solicited information on the feasibility of compliance with the proposed standard. After the post-hearing comment period had closed, the Center for Emissions Control sent OSHA materials with a cover letter from Mr. Stephen P. Risotto, detailing an ongoing analysis of adhesive use in foam manufacturing facilities and a request for OSHA to "consider the inability of foam adhesive operations to meet the proposed occupational limits before issuing a final rule." The CEC submission also included a document entitled "Foam Adhesive-Ventilation Project Description," which outlined the protocol for investigating potential engineering controls and feasibility for this sector, and a preliminary report entitled "Foam Adhesive Fabrication Ventilation Study," conducted by Rust Engineering Company, which outlined recommendations to improve the ventilation systems for the spray booths, including costs of modifications.

OSHA preliminarily determined that it was technologically and economically feasible for establishments that use adhesives to comply with the proposed standard or substitute away from MC. In this Federal Register notice, OSHA is soliciting comments on the submitted protocol and report and requesting information on the technological and economic feasibility of compliance with the proposed standard for adhesive use in this situation.

II. Public Participation


Written comments regarding the materials incorporated into the methylene chloride rulemaking record through this notice must be postmarked by April 25, 1994. Four copies of these comments must be submitted to the Docket Office, Docket No. H-071A, U.S. Department of Labor, room N-2625, 200 Constitution Avenue, NW., Washington, DC 20210. (202) 219-7894. All materials submitted will be available for inspection and copying at the above address. Materials previously submitted to the Docket for this rulemaking need not be resubmitted.

III. Authority

This document was prepared under the direction of Joseph A. Dear, Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210.

It is issued under section 6(b) of the Occupational Safety and Health Act (29 U.S.C. 655), and 29 CFR part 1911.

Signed at Washington, DC, this 8th day of March 1994.

Joseph A. Dear,
Assistant Secretary of Labor.

[FR Doc. 94-5752 Filed 3-10-94; 8:45 am]