US EPA

17608 

Technical Report 

Airborne asbestos health assessment update 

U.S. Environmental Protection Agency :: U.S. EPA 

1986 

U.S. Environmental Protection Agency, Environmental Criteria and Assessment 

Washington DC 

EPA/600/8-84/003F 

215 

English 

Data developed since the early 1970s, from large population studies with long follow-up, have added to our knowledge of asbestos-related diseases and strengthened the evidence for associations between asbestos and spercific types of health effects. Lung cancer and mesothelioma are the most important asbestos-related causes of death among exposed individuals. Cancer at other sites also has been associated with asbestos exposure. The accumulated data sugest that the excess risk of lung cancer from asbestos exposure is proportional to the cumulative exposure (the duration times the intensity) and the underlying risk in the absence of exposure. The risk of death from mesothelioma is approximately proportional to the cumulative expsoure to asbestos and increases sharply with time since onset of exposure. Animal studies confirm the human epideiological results and indicate that all major asbestos varieties produce lung cancer and mesothelioma, with only limited differences in carcinogenic potency. Some measurements demonstrate that asbestos exposures exceeding 100 times background occur in non-occupational environments. Currently, the most important of these non-occupational exposures is the release of fibers from asbestos-containing surfacing materials in schools, auditoriums, and other public buildings, or from sprayed asbestos fireproofing in high-rise office buildings. Extrapolations of risks of asbestos cancers from occupational circumstances can be made, although numerical estimates in a specific exposure circumstance have a large (approximately tenfold) uncertainty. Because of this uncertainty, calculations of unit risk values for asbestos at low concentrations must be viewed with caution. They are subjective, to some extent, and are also subject to the following limitations in data: 1) variability in the exposure-response relationship at high exposures; 2) uncertainty in extrapolating to exposures 1/100 as much; and 3) uncertainties in conversion of optical fiber counts to electron microscopic fiber counts or mass determinations. 

Pollution Abstracts; asbestos; carcinogenesis; diseases; occupational health; P 6000:TOXICOLOGY AND HEALTH 

PB86-42864