Occupational Exposure to Methylene Chloride

The Occupational Safety and Health Administration (OSHA) hereby amends its existing regulations for employee exposure to methylene chloride (MC), (also known as methylene dichloride, dichloromethane or DCM). OSHA has determined, based on animal and human data, that the current permissible exposure limits (PELs) allow employee exposure to a significant risk of material impairment of health. OSHA is reducing the existing 8-hour time-weighted average (TWA) exposure from 500 parts MC per million parts (ppm) of air to 25 ppm. Also, OSHA is deleting the existing ceiling limit concentration of 1,000 ppm and is reducing the existing short-term exposure limit from 2,000 ppm (measured over five minutes in any 2 hour period) to 125 ppm, measured as a 15-minute TWA. In addition, the Agency is setting an ``action level'' of 12.5 ppm, measured as an 8-hour TWA. The final rule also contains provisions for exposure control, personal protective equipment, employee exposure monitoring, training, medical surveillance, hazard communication, regulated areas, and recordkeeping. Together, these provisions will substantially reduce significant risk to the extent feasible. This standard applies to all employment in general industry, shipyards and construction. Small employers, for purposes of the Regulatory Flexibility Act, 5 U.S.C. 601, are defined as firms with fewer than twenty employees. The final standard will prevent an estimated 31 cancer deaths per year and an estimated three deaths per year from acute central nervous system and carboxyhemoglobinemic effects, and will also reduce cardiovascular disease and material impairment of the central nervous system. The estimated cost, on an annualized basis, is $101 million per year.