A 1997 federal regulation limiting worker exposure to the toxic solvent methylene chloride has saved lives and prevented serious illness, OHSA says, and it will remain in place as currently written, a review by the agency has determined.
Methylene chloride (also known as MC, dichloromethane, or DCM) is a common industrial solvent used in paint stripping, metal cleaning, manufacturing of plastics and adhesives, and other applications. Without proper ventilation or respiratory protection, short-term exposure to large amounts of MC can cause respiratory or central nervous system failure.
In 1985, the U.S. EPA determined that MC was a probable human carcinogen and posed a long-term danger to human health. In 1997, the Occupational Safety and Health Administration reduced the permissible exposure limit of MC from an eight-hour-time-weighted-average (TWA) of 500 parts per million to 25 parts per million.
As required, OSHA has been conducting an extensive review of the standard, to determine how well it was fulfilling its purpose of safeguarding workers.
“The review clearly showed that the standard has been effective in saving lives,” OSHA recently reported. “The study estimates that each year the standard protects as many as 30,000 to 54,000 workers from damage to their respiratory and nervous systems and prevents approximately 34 deaths from cancer and other illnesses caused by methylene chloride exposure. This standard’s success reflects the overall importance of OSHA standards in protecting workers' safety and health.”
The notice was published May 5 in the Federal Register (Federal Register Number 75:24509-24510, Standard Number 1910.1052).
“OSHA concludes that the MC Standard has protected workers from adverse health effects resulting from exposure to MC in the workplace,” OSHA said. “In terms of economic impacts, the MC Standard does not impose an unnecessary or disproportionate burden on small businesses or on industry in general. Although the Standard does impose costs, these costs are essential to protecting worker health. This lookback review did not identify any industries in which the MC Standard diminished the industries' viability.”
Although the standard will not change, OSHA has found that lack of information and training are the most common barriers to compliance. The agency thus “recommends reviewing its compliance-assistance materials to determine the need for updates. OSHA also recommends reviewing the adequacy of how these materials are disseminated and additional means for reaching affected populations.”
Substitutes for MC have been developed and their use is growing, but OSHA notes that even these “may pose their own health hazards.”
“Therefore, based on public comments, OSHA will consider putting out guidance recommending that, before a substitute for MC is used, the toxicity of that substitute should be checked on the EPA and NIOSH Web sites (http://www.epa.gov and http://www.niosh.gov, respectively).”