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
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 OSHAs 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, didnt even attend Dr. Franklin Mirer of the United Auto
Workers testified that:
OVERDUE, SOUND, FEASIBLE
"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 OSHAs new and tighter
exposure limit." The current standard of 500 parts per million was first
adopted by OSHA in 1971, and by OSHAs own estimates will result in 12 cancer deaths
for every 100 workers one out of every eight workers exposed
regularly at this level. Whats 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, its still a nasty solvent.
Pure methylene chloride is a clear, colorless, volatile liquid with a
characteristic, ether-like odor. Most humans cant smell its vapors until the
concentration level reaches 250 parts per million, far above OSHAs new limit.
OTHER HEALTH EFFECTS
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 bodys 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.
WHAT TO DO
If you are routinely exposed, your locals 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
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 lets save the
standard, even if in the end we have to enforce it ourselves in the shop.