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Why Methylene Chloride
Is Worth Worrying About

UE News, May 1997

Methylene chloride has been used for decades in paint strippers and rubber cements, as a solvent in vapor degreasing tanks, as a propellant for sprays (such as hair sprays), and as a blowing agent in the manufacture of flexible foams. In 1985, the U.S. Environmental Protection Agency (EPA) determined, based primarily on animal studies, that methylene chloride is a "probable human cancer agent."

In 1997, after 12 years of hemming and hawing, the Occupational Safety and Health Administration (OSHA) finally decided to enact a new methylene chloride standard. The standard, which went into effect April 10, 1997 for most industries, will reduce the legal limit exposure from 500 to 25 parts per million in air over an 8-hour workday. This would reduce exposure-related deaths by at least 97 percent for more than one quarter of a million U.S. workers, and prevent an average of 34 worker deaths per year.

But this is too much for some Congressional Republicans, especially those from the State of Mississippi. In March, Rep. Roger Wicker (R., Miss.) introduced a bill in the U.S. House of Representatives (HJ Res 67) to overturn OSHA’s new methylene chloride standard. On April 10, Sen. Thad Cochran (R., Miss.) introduced a companion U.S. Senate resolution (HJ Res 25). Both are using a little-noticed provision in the Small Business Regulatory Enforcement Fairness Act, passed last year and signed into law by President Clinton, which allows Congress to overturn any OSHA standard if it is judged to harm small businesses. Such an override must be passed by both the House and Senate and be signed by the President to take effect.

At a hearing on the House resolution on April 16 — a hearing Rep. Wicker, the sponsor, didn’t even attend — Dr. Franklin Mirer of the United Auto Workers testified that:


  • "The biggest concern with the methylene chloride standard should be the long delay in providing protection for workers." (The UAW petitioned for a standard in 1985.)

  • "Sound science supports OSHA’s new and tighter exposure limit." The current standard of 500 parts per million was first adopted by OSHA in 1971, and by OSHA’s own estimates will result in 12 cancer deaths for every 100 workers — one out of every eight workers — exposed regularly at this level. What’s more, hundreds of animal and human health studies since that time have revealed a variety of health effects from this commonly-used solvent.

  • "The Standard is technically and economically feasible." Good ventilation can dramatically reduce solvent vapor levels during paint stripping and plastic foam manufacture. During spray-on operations, ordinary paint spray booths can provide adequate worker protection. And in many uses, other safer solvents can be used in place of methylene chloride.

Is methylene chloride used in your shop. Check the label or MSDS (material safety data sheet) about this. Because methylene chloride is suspected to be a human cancer agent, many manufacturers try to disguise its use by using other chemical names for it. Other names for methylene chloride include dichloromethane, DCM and methylene dichloride. By any name, it’s still a nasty solvent.

Pure methylene chloride is a clear, colorless, volatile liquid with a characteristic, ether-like odor. Most humans can’t smell its vapors until the concentration level reaches 250 parts per million, far above OSHA’s new limit.


Like any solvent vapors, methylene chloride can affect the human nervous system, causing headache, dizziness and nausea, and at very high levels numbness in the fingers and toes, unconsciousness and even death.

Also, when methylene vapors enter the blood stream, they break down to form carbon monoxide. This reduces the levels of oxygen uptake by the blood, making your heart work harder to provide enough oxygen to your body’s cells. The effect, even of long-term, low-levels of exposure, can be a higher rate of heart attacks, and greater heart damage after an attack.


  • If you are routinely exposed, your local’s health and safety committee should press for good local exhaust ventilation, regularly inspected and maintained.

  • Make sure all solvent operations are enclosed as much as possible. Make sure all carrying containers are sealed during transit, and that lids are regularly kept on all solvent tanks and trays when not in use.

  • Wear long-sleeved shirts when the weather permits, and use chemical protective clothing and safety goggles as protection from splashes.

And write your members of Congress and urge them to reject HJ 67 and SJ 25. We need a Methylene Chloride Standard. But let’s save the standard, even if in the end we have to enforce it ourselves in the shop.

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