Occupational Safety and Health Administration (1998)
On January 10, 1997, the Occupational Safety and Health Administration (OSHA) issued a standard that lowered the limit on worker exposures to methylene chloride (MC). This new standard greatly reduces the chance of developing health problems from working in facilities that use MC.
Worker exposures to MC occur mainly through breathing its vapors. MC can also pass through workers' skin if it gets on their bodies or clothes. Occasionally, workers can swallow small amounts of MC if they don't wash their face and hands before eating, or if they eat in contaminated work areas. Short-term exposure to high levels of MC can cause dizziness, headaches, a lack of coordination, and irritation of the skin, eyes, mucous membranes, and respiratory system. Long-term exposure causes cancer in laboratory animals. Studies in workers suggest an association between MC exposures and certain types of cancer. OSHA considers MC to be a potential occupational carcinogen. Exposure to MC may also make the symptoms of heart disease (e.g., chest pains, angina) worse.
Monitoring employee exposures to MC enables employers to identify the sources of MC and select appropriate exposure controls. OSHA's MC standard requires that all facilities using MC monitor employee exposures. This fact sheet provides only general information on monitoring requirements and should not be considered to be a complete summary of the MC-related monitoring requirements. For specific exposure monitoring requirements, please refer to the OSHA MC standard (Title 29 of the Code of Federal Regulations, Part 1910.1052(d)). The MC standard can be accessed at OSHA's web site.
If MC is used in the workplace, the employer must monitor employee exposure to MC to determine if any employee is being exposed to MC in excess of the permissible exposure limits (PELs): 25 ppm, as an 8-hour time-weighted average (TWA) PEL; and 125 ppm, as a 15 minute short-term exposure limit (STEL). Employers are required to conduct initial monitoring of airborne MC concentrations and to conduct periodic MC exposure monitoring for all tasks where employee exposures are above the action level (12.5 ppm, 8-hour TWA) or STEL. Validated monitoring methods include OSHA Method 80 (available through OSHA's web site), badge monitoring, and other methods that meet the accuracy and precision requirements of the MC standard.
Initial monitoring is not necessary if:
If initial monitoring shows employee exposures at or above the action level or STEL, employers must perform periodic 8-hour TWA or STEL monitoring as follows:
8-hour TWA monitoring:
If two consecutive measurements, taken at least 7 days apart, show that exposure levels have decreased, employers may modify the monitoring requirements accordingly*.
*Those specified industries taking advantage of the new extended compliance dates published in the revised final rule on September 22, 1998 (FR 63; 50712-50732) must monitor STEL exposures every three months until either the date by which they must achieve the 8-hour TWA PEL, or the date by which they in fact achieve the 8-hour TWA PEL, whichever comes first. These specific industries include polyurethane foam manufacturing; foam fabrication; furniture refinishing; general aviation aircraft stripping; product formulation; use of MC-based adhesives for boat building and repair, recreational vehicle manufacture, van conversion, or upholstery; and use of MC in construction work for restoration and preservation of buildings, painting and paint removal, cabinet making, or floor refinishing and resurfacing.
Employers must perform additional monitoring if there is an indication that employee exposures have increased. Examples include changes in the production process, control equipment, or work practices that could increase exposure levels; and leaks, ruptures, or other equipment breakdowns.
In determining each employee's workplace exposure to MC, employers may take either:
Personal breathing zone air samples may be considered representative of an employee's 8-hour TWA and 15-minute short-term exposures if:
Employers are required to notify employees of all monitoring results, in writing, within 15 working days of receiving the results. If exposures are above the PEL or STEL, the employer must inform the employee of the corrective actions being taken.
OSHA's standard requires employers to allow affected employees or their designated representatives to observe any monitoring activities. Where such observations involve entry into areas where personal protective equipment (PPE) is necessary, the employer must provide and ensure the use of the appropriate PPE. In addition, the employer must ensure that observers follow all other applicable safety and health procedures.
Employers must establish and keep accurate records of all exposure monitoring data as well as the objective data used to support exemptions from initial monitoring requirements.
Exposure Monitoring Data:
Employers with 20 or more employees must keep exposure monitoring records for 30 years. The records must include information on:
Employers with fewer than 20 employees must also keep records for 30 years, but only need to include information on:
Objective data records must be kept as long as the employer relies on this data and include information on:
For more information concerning consultation assistance, contact the nearest OSHA office (look under state listings for the Department of Labor), refer to the listings on OSHA's web site, or contact OSHA's Office of Information at (202) 219-8151.Back to Top
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