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 body 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.
About 6,590 furniture refinishing establishments use products that contain MC. In many
facilities, just improving work practices and housekeeping procedures can greatly reduce
exposure to MC. The following suggested practices may help you reduce your workplace
exposures.
Keep MC Vapors Contained
- Keep the door to mixing/storage areas closed at all times.
- Store and transport MC only in approved safety containers.
- Properly label all MC containers to indicate their contents, hazards, and proper use,
storage and disposal. Read these labels and follow the directions.
- Keep solution containers closed tightly when not in use.
- Avoid unnecessary transfer or movement of stripping solutions.
- Keep dip tanks and reservoir tanks covered when not in use.
- Keep the stripping solution at the appropriate temperature (often around 70F). At this
temperature, wax in the solution will form a vapor barrier that prevents the solution from
evaporating too quickly. If the temperature is too high or too low, the wax will not form
a vapor barrier.
- Do not let sludge dry on the stripping table. Place the wet sludge in sealed containers
for later recovery or disposal, or dry it using proper engineering controls (e.g., local
exhaust ventilation) to capture the MC vapors.
Avoid Breathing MC Vapors
- Turn on the dip tank or stripping table ventilation system at least an hour before work
begins or leave it on overnight.
- Avoid breathing air directly above the stripping solution and dip tank. Do not lean over
the tank when working.
- Avoid breathing the air directly above the furniture during manual stripping. Do not
lean over an area covered with stripper.
- Do not work or stand between solution-covered furniture and the exhaust system.
- Turn the solution-recycling system off when it is not being used.
- Do not rely on the odor of MC to warn you of over-exposure. People cannot smell MC until
vapor concentrations are above 300 ppm, which is 12 times higher than the 8-hour
time-weighted average permissible exposure limit of 25 ppm. Also, your sense of smell can
quickly get used to the odor of MC so that you stop noticing it.
- If you become dizzy, light-headed, or have other symptoms of MC exposure, go immediately
to an area with fresh air.
Avoid Direct Skin Contact with MC
- Wear two pairs of gloves when using stripping solution. The inner glove should be made
of polyethylene (PE)/ethylene vinyl alcohol (EVOH), PE, or laminate to prevent MC
penetration. The outer glove should be made of nitrile or neoprene to protect against
puncture or rips. [Note: Because MC can readily penetrate nitrile and neoprene, wearing
just the outer glove will not protect your skin from MC exposure.]
- Wear shoulder length gloves, or the longest gloves possible.
- Before use, inspect gloves for pin-holes, cracks, thin spots, softening, swelling, and
stiff or sticky surfaces.
- Change gloves frequently, before breakthrough occurs.
- Rotate several pairs of gloves throughout the day.
- Let gloves dry in a warm, well-ventilated area at least overnight before reuse.
- Wear rubber aprons and boots or shoe covers to prevent MC from getting on your clothes
which results in prolonged skin contact with MC.
- Wear a face shield or goggles to protect your face and eyes.
- Use the washing facilities in your work area to wash off any MC from your hands and
face.
- Use lots of soap or mild detergent and water to clean grease, oil, dirt, or anything
else off your skin. Do not use MC or other organic solvents to clean your skin.
Minimize the Chance of Spills and Leaks
- Develop and follow your facility's procedures for detecting MC leaks from process
equipment, holding tanks, and spill control devices.
- Frequently inspect process equipment, holding tanks, and spill control devices for
cracks, loose parts, and other possible sources of leaks.
- Where spills occur, follow procedures for containing them.
- Clean up all spills and leaks as quickly as possible.
- Place rags, waste, paper towels, or absorbent used to clean spills in a closed container
(preferably a non-aluminum, all-metal safety container) immediately after use.
- Make sure that leaks are repaired and spills cleaned up by employees who are trained in
proper cleanup methods. These employees should wear appropriate personal protective
equipment (PPE).
Take Extra Precautions in Low and Confined Spaces
MC vapors are heavier than air, so they tend to move to low, unventilated spaces such
as tanks and maintenance pits.
- Do not enter or lean into a storage tank, dip tank, or low-lying confined area until it
has been completely aired out and tested. Wear proper PPE and follow the appropriate
confined space entry procedures outlined in OSHA's Permit Required Confined Spaces standard
(29 CFR 1910.146).
- Use a long-handled tool to pick up items that you drop into a confined space or
low-lying area.
Take Personal Precautions
- After working with MC, always wash your face and hands before eating.
- Never eat in the work area or your food and drink could become contaminated with MC.
- Avoid drinking alcohol before or after being exposed to MC. Alcohol can lower the amount
of MC needed to cause health problems.
- Be alert when working with MC. Avoid situations that might result in overexposure.
- If your clothes become soaked with MC, remove them and take a shower. Do not put your
clothes back on until they are thoroughly clean and dry.
Respirators
If engineering controls and work practices do not reduce MC exposures to an acceptable
level, workers must wear supplied-air respirators. Respirators are the least preferred
method of controlling employee exposures. Supplied-air respirators must have a clean air
supply through the use of compressed air tanks containing air meeting at least the
requirements for Grade D breathing air, or a breathing air type compressor with the air
intake located in an area with a clean air supply.
CAUTION: Filter cartridge respirators cannot be used because MC can
pass through available cartridges leaving respirator wearers unprotected.
Compliance Schedule
Employers with 1 to 20 employees have until:
- February 4, 1998 to implement paragraph (d) (Initial Monitoring).
- April 10, 2000 to implement paragraph (f) (Engineering Controls).
- April 10, 2000 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- April 10, 1998 to implement all other provisions.
Employers with 20 to 49 employees have until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- April 10, 2000 to implement paragraph (f) (Engineering Controls).
- April 10, 2000 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- December 21, 1997 to implement all other provisions.
Employers with 50 or more employees have until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- April 10, 1999 to implement paragraph (f) (Engineering Controls).
- April 10, 1999 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- December 21, 1997 to implement all other provisions.
Additional Resources
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.
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