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Methylene Chloride Fact Sheet
Methylene chloride is used as a solvent, especially where high volatility is required. It is a good solvent for oils, fats, waxes, resins, bitumen, rubber and cellulose acetate and is a useful paint stripper and degreaser. It is used in paint removers, in propellant mixtures for aerosol containers, as a solvent for plastics, as a degreasing agent, as an extracting agent in the pharmaceutical industry, and as a blowing agent in polyurethane foams. Its solvent property is sometimes increased by mixing with methanol, petroleum naphtha, or tetrachloroethylene. The Occupational Safety and Health Administration (OSHA) estimates that approximately 35,000 workers are exposed to methylene chloride.
Studies indicate that there is suggestive, but not absolute evidence that methylene chloride is a human carcinogen. Long-term respiratory exposure in excess of 25 parts per million (ppm) is reported to be associated with an increased risk of cancer of the bile duct and brain.
Short term (acute) airborne exposures to high concentrations more than 125 ppm may cause mental confusion, light-headedness, nausea, vomiting, and headache. Continued exposure may also cause eye and respiratory tract irritation. Exposure to methylene chloride may make symptoms of angina (chest pain) worse. Skin exposure to liquid methylene chloride may cause irritation. Liquid methylene chloride placed on the skin may cause chemical burns.
Activities where exposure to methylene chloride is possible is in using paint strippers, working in laboratories, and parts degreasing. These areas should be initially and periodically assessed for exposures.
- 29 CFR 1910.1052 - Methylene chloride (OSHA - General Industry)
- 29 CFR 1926.1152 - Methylene chloride (OSHA - Construction)
- 29 CFR 1910.132- Personal Protective Equipment (OSHA - General Industry)
- 29 CFR 1910.133- Eye and Face Protection (OSHA - General Industry)
Summary of Requirements
Must be performed initially for employees exposed to methylene chloride unless objective data demonstrates that methylene chloride cannot be released into the workplace in airborne concentrations at or above the action level or above the STEL. The objective data shall represent the highest methylene chloride exposures likely to occur under reasonably foreseeable conditions of processing, use, or handling. All objective data shall be documented.
All employees who may be exposed at or above the action level of 12.5 ppm in an 8- hour shift on a Time-Weighted Average Permissible Exposure Limit (TWA-PEL); or, the Short Term Exposure Limit (STEL) of 125 ppm averaged over any 15-minute period during the work shift.
Exposures below the AL, but above the STEL, must be monitored for STEL exposures every three months. For exposures at or above the AL, but below or at the TWA-PEL of 25 ppm and below the STEL, monitoring shall be repeated for 8-hour TWA-PEL exposures every six months. For exposures above the TWA-PEL and at or below the STEL, monitoring shall be repeated every three months. For exposures above the TWA-PEL and above the STEL, monitoring for the 8-hour TWA-PEL and STEL shall be performed every three months
Reduction in monitoring
If the results from two consecutive 8-hour TWA-PEL samples taken at least 7 days apart indicate employee exposure below the action level and the STEL, monitoring may be discontinued, unless there is a change in the product or the process.
Employees shall be notified in writing within 15 days after the receipt of any monitoring the results of the air samples taken in their breathing zones. Whenever samples indicate that employees results are above the 8-hour TWA-PEL or the STEL, the employer shall describe in the written notification the corrective action being taken to reduce exposure to or below the 8-hour TWA-PEL or STEL and the schedule for completion of this action.
Regulated areas shall be established whenever an employee's exposure to airborne concentrations of methylene chloride concentrations exceed the TWA-PEL or the STEL. They shall be demarcated from the rest of the workplace in any manner (such as yellow barrier tape or signs) that adequately establishes and alerts employees to the boundaries of the area and minimizes the number of authorized employees exposed within the regulated area.
Engineering controls and work practices shall be instituted to maintain exposures below the TWA-PEL or STEL. Where necessary, controls may be supplemented with respiratory protection.
Where respirators are required, they will be provided at no cost to the employee, and will reduce methylene chloride exposures to levels at or below the TWA-PEL and STEL. Since organic vapor cartridge respirators do not protect against methylene chloride, only appropriate atmosphere-supplying (air fed) respirators can be used. Whenever a respirator is required, a respiratory protection program conforming with OSHA regulations will be instituted.
Protective Equipment and Clothing
Protective clothing and equipment shall be provided to each employee in order to prevent methylene chloride-induced skin and eye irritation. All eye and face protection shall meet OSHA requirements. All personal protective equipment shall be made of material that is impervious to methylene chloride.
Conveniently located washing facilities capable of removing methylene chloride shall be provided for all employees whose skin may come into contact with solutions containing 0.1 percent or greater methylene chloride. Appropriate emergency eye washes shall be made available to all employees who may have eye contact (for example, splashes, spills or improper work practices) to methylene chloride solutions containing 0.1 percent or greater methylene chloride.
Preventative maintenance of equipment, including visual inspections for leaks and spills, will be performed regularly. In areas where there spillage may occur, provisions will be made to contain spills, decontaminate the work area, and dispose of the waste. Employees repairing equipment leaks and cleaning up spills will be properly trained and will wear suitable protective equipment. Methylene chloride contaminated waste will be disposed of by following UMD waste disposal guidelines.
Institute medical surveillance programs for all employees exposed to methylene chloride at concentrations at or exceeding the action level on 30 or more days per year or above the TWA-PEL or STEL on more than 10 days per year. Medical disease questionnaires and medical examinations shall be administered. All medical procedures will be performed by or directly supervised by the University Health Center Occupational Health Unit.
All employees with any potential exposure to methylene chloride must receive training to provide an understanding of hazards and protection methods. Employees assigned to work sites where exposure to methylene chloride is at or above the action level shall be informed of the requirements of the OSHA Standard 29 CFR 1910.1052 or 29 CFR 1926.1152. Training shall be provided at the time of initial assignment and whenever a new exposure to methylene chloride is introduced into the work area.
Records shall be maintained for all of the following:
- All measurements taken to monitor employee exposure to methylene chloride
- All training
- Medical surveillance
- Respirator fit testing
- All exposure records and determinations shall be kept for at least 30 years
- All medical records shall be kept for the duration of employment plus 30 years
- All respiratory fit test records shall be kept until replaced by a more recent record
Department of Environmental Safety, Sustainability and Risk (301) 405-3960
ESSR Fax Number: 307-314-9294
ESSR online: https://essr.umd.edu