NIOSH Recommends Precautions to Curb Possible Exposures of Workers to Asbestos Linked with Vermiculite From Libby, Montana

NIOSH Update:

Contact: Fred Blosser (202) 401-3749
May 21, 2003

The National Institute for Occupational Safety and Health (NIOSH) today issued a fact sheet 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 ZonoliteTM Attic Insulation, but not all ZonoliteTM 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.
  • When a work activity involves vermiculite known or presumed to be contaminated with asbestos, the Occupational Safety and Health Administration’s asbestos standards should be consulted.
  • If vermiculite is known or presumed to be contaminated with asbestos, general precautions should be followed to limit potential asbestos exposure: Avoiding the handling or disturbance of loose vermiculite. Isolating work areas with temporary barriers or enclosures. Using wet control methods if feasible. Avoiding use of compressed air for cleaning. Avoiding dry sweeping or other dry clean-up methods. Using disposable protective clothing or clothing that is left in the workplace. Using proper respiratory protection. Disposing of waste and debris in accordance with OSHA and Environmental Protection Agency standards.
  • Workers who have had significant past exposure, or have significant on-going exposure, to asbestos, to vermiculite from Libby, or to other asbestos-contaminated materials should consider getting a medical examination from physician who knows about diseases caused by asbestos.

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 toll-free NIOSH information number 1-800-35-NIOSH (1-800-356-4674).

Page last reviewed: July 22, 2015