Asbestos remains an environmental hazard in 2009. Just how many U.S. workers are still exposed to asbestos fibers on the job is unknown, but OSHA estimated in 2008 that 1.3 million workers in construction and general industry may still face significant exposures. NIOSH now has released a revised current intelligence bulletin (the full bulletin is located at www.cdc.gov/niosh/review/public/099-C/pdfs/AsbestosRoadmapPublicDraftV4a.pdf ) for asbestos fibers in which the agency explains what it still wants to research and clarifies the 1990 NIOSH recommended exposure limit (REL) for airborne asbestos fibers.
That REL, 0.1 airborne asbestos fibers per cubic centimeter, has created confusion over which materials included in the NIOSH definition are “asbestos” and whether the definition is optimal for protecting workers’ health. The revised document, for which NIOSH seeks comments by April 16, clarifies but does not change the exposure limit. The REL now is “0.1 countable elongate mineral particles from one or more covered minerals per cubic centimeter averaged over 100 minutes where:
• A countable elongate mineral particle (EMP) is an fiber or fragment of a mineral longer than 5 um with a minimum aspect ratio of 3:1 when viewed microscopically using NIOSH Analytical Method #7400(‘A’ rules) or its equivalent; and
• A covered material is any mineral having the crystal structure and elemental composition of: one of the asbestos varieties (chrysotile, riebeckite asbestos [crocidolite], cummingtonite-grunerite asbestos [amosite], anthophyllite asbestos, tremolite asbestos, and actinolite asbestos) or one of their nonasbestiform analogs (the serpentine minerals antigorite and lizardite, and the amphibole minerals contained in the cummingtonite-grunerite mineral series, the tremolite-ferroactinolite mineral series, and the glaucophane-riebeckite mineral series.)”
The NIOSH draft indicates U.S. imports of asbestos have dropped from 35,000 metric tons in 1991 to under 3,000 metric tons in 2006 and 2007, with domestic production having ceased in 2003. However, worldwide use stood at 2 million metric tons as recently as 2006, mainly for use in building materials, according to the draft.
Approximately 3,000 individuals are diagnosed annually in the US with mesothelioma, a cancer of the lining of the lung caused by asbestos exposure. Still others continue to be diagnosed with other asbestos-related diseases such as lung cancer and asbestosis. Because of the long latency period between exposure and related disease, asbestos related deaths in the United States “are anticipated to occur for several decades,” according to the draft.