June 9, 2003—The National Institute for Occupational Safety and Health (NIOSH) issued a fact sheet May 21 with recommendations for limiting occupational exposures to asbestos associated with vermiculite from Libby, Montana. NIOSH cautions that, in general, any vermiculite that originated from a mine near Libby should be regarded as potentially contaminated with asbestos.
People may be occupationally exposed to vermiculite in work-related activities involving insulation and other construction or home materials, agricultural and horticultural materials such as potting mixes and soil conditioners, brake shoes and pads, and other products. Available data, including information collected and reported by NIOSH to miners and others in Libby in the 1980s, show that vermiculite ore mined near Libby until 1990 was contaminated with asbestos and asbestos-like fibers.
Much of the vermiculite from the mine near Libby was used in the manufacture of Zonolite Attic Insulation, but not all Zonolite product was made with vermiculite from that same mine. NIOSH’s findings and recommendations in the fact sheet, pending additional research and technical assistance that NIOSH is conducting to answer current questions about occupational exposures to vermiculite, include these:
- As with any asbestos-containing or asbestos-contaminated material, the only way to know the amount of asbestos present is to have the material tested. Negative results from testing can be falsely reassuring when less than 1% of the sample is asbestos. Disturbing contaminated vermiculite with less than 1% asbestos can still result in hazardous concentrations of airborne asbestos fibers.
- If vermiculite is known or presumed to be contaminated with asbestos, general precautions should be followed to limit potential asbestos exposure: Avoid handling or disturbing loose vermiculite. Isolate work areas with temporary barriers or enclosures. Use wet control methods if feasible. Avoid use of compressed air for cleaning. Avoid dry sweeping or other dry clean-up methods. Use disposable protective clothing or clothing that is left in the workplace. Use proper respiratory protection. Dispose of waste and debris in accordance with OSHA and Environmental Protection Agency (EPA) standards.
The full fact sheet, “NIOSH Recommendations for Limiting Potential Exposures of Workers to Asbestos Associated with Vermiculite from Libby, Montana,” DHHS (NIOSH) Publication No. 2003-141, is available by calling the NIOSH information number, 800/35-NIOSH (800/356-4674), or visiting NIOSH.
