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Methylene Chloride Facts No. 7
Suggested Work Practices for
Flexible Polyurethane Foam Manufacturers
Occupational Safety and Health Administration (1998)
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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.
Many flexible polyurethane foam (p-foam) manufacturing facilities use MC as a blowing
agent to make soft foam. Most p-foam manufacturing facilities use engineering controls to
lower MC levels. However, at some facilities just improving work practices and
housekeeping procedures can greatly reduce exposures to MC. The following suggested
practices may help you reduce your workplace exposures.
Keep MC Vapors Contained
- Keep the doors to the pouring and cooling 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 MC containers closed tightly when not in use.
- Avoid unnecessary transfer or movement of MC.
- Keep the openings on the sides of the tunnel closed when it is not in use. This keeps MC
vapors from escaping and ensures that the makeup air system at the end of the tunnel runs
well.
Avoid Breathing MC Vapors
- Turn on local exhaust ventilation systems in the tunnel and cooling rooms at least an
hour before work begins or leave them on overnight.
- Turn on the general ventilation system in the cooling room at least an hour before work
begins or leave it on overnight.
- Avoid breathing air directly above cooling foam.
- When possible, minimize the amount of time spent near the cooling foam and tunnel
openings because these areas are likely to have the highest levels of MC vapors.
- Do not work or stand between cooling foam and the exhaust system.
- Do not rely on the odor of MC to warn you of overexposure. 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 MC. 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 the tunnel and other equipment for cracks, loose parts, and other
possible sources of MC leaks.
- 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.
- Do not enter or lean into a 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.
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 for controlling employee exposure. 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 in p-foam manufacturing with less than 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 in p-foam manufacturing with 20 - 99 employees have until:
- December 21, 1997 to implement paragraph (d) (Initial Monitoring).
- October 10, 1999 to implement paragraph (f) (Engineering Controls).
- October 10, 1999 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- January 5, 1998 to implement all other provisions.
Employers in p-foam manufacturing with 100 or more employees have
until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- October 10, 1999 to implement paragraph (f) (Engineering Controls).
- October 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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