Occupational Exposure to Methylene Chloride

DEPARTMENT OF LABOR

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.

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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.

SUPPLEMENTARY INFORMATION:

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 methy chloroform

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

Comments

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]

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