Asbestos occupational exposure

Occupational Exposure Eimitfor Asbestos, Report of a WHO Meeting, Oxford, UK, Apr. 10-11, 1989. 

Work with asbestos insulating board (superseded by EH 71j Ozone health hazards and precautionary measures Occupational exposure limits (annual)... 

The a-tocopherol, P-carotene (ATBC) Cancer Prevention study was a randomised-controlled trial that tested the effects of daily doses of either 50 mg (50 lU) vitamin E (all-racemic a-tocopherol acetate), or 20 mg of P-carotene, or both with that of a placebo, in a population of more than 29,000 male smokers for 5-8 years. No reduction in lung cancer or major coronary events was observed with any of the treatments. What was more startling was the unexpected increases in risk of death from lung cancer and ischemic heart disease with P-carotene supplementation (ATBC Cancer Prevention Study Group, 1994). Increases in the risk of both lung cancer and cardiovascular disease mortality were also observed in the P-carotene and Retinol Efficacy Trial (CARET), which tested the effects of combined treatment with 30 mg/d P-carotene and retinyl pahnitate (25,000 lU/d) in 18,000 men and women with a history of cigarette smoking or occupational exposure to asbestos (Hennekens et al, 1996). 

Figure 1. The age-specific incidence of lung cancer deaths in male cigarette smokers and nonsmokers (Kahn, 1966, Appendix Table A). The lifetime incidence for nonsmokers includes lung cancers attributable to passive smoking, asbestos inhalation, and other occupational exposures.

Fiber has been given a legal, if not operational definition, at least as it applies to asbestos. Unfortunately tlie definition bears little relationship to the present use of the term. It was essential to set standards to reduce occupational exposure but the detection, identification, and suppression of asbestos materials opened several areas of problems that remain unsolved. For example, six minerals are included in the definition of asbestos. Are they all equally hazardous If not, why not There are many other inorganic particles with diameters of less than 3 micrometers and a diameter-to-length ratio of 1 3. Should we be concerned that they too might be hazardous to our health ... 

Occupational Safety and Health Administration (OSHA) (1972, 1976, 1983, 1986). Occupational Exposure to Asbestos, Tremolite, AnthopylUte and Actinolite Final Rules. 29 CFR Parts 1910 and 1926. 

The initial connection between asbestos and mesothelioma was made by Wagner et al. (1960), when all but one patient in a study of mesothelioma-related deaths were found to be miners, workers, members of their families, or others living in the area of South Africa where the amphibole-asbestos crocidolite was mined. A comparable occupational exposure to crocidolite has been documented in Australia, with similar results (Armstrong et al., 1984). Mann and his associates (1966) documented three cases of mesothelioma among fifty-four patients dying of pulmonary asbestosis, and in two of the patients the mesotheliomas were peritoneal rather than pleural. 

Enterline, P. P., P. de Coufle, and V. Henderson (1975). Respiratory cancer in relation to occupational exposures among retired asbestos workers. Br. J. Indust. Med. 30 162-166. 

Walton, W. H. (1982). The nature, hazards and assessment of occupational exposure to airborne asbestos dust a review. Ann. Occup. Hyg. 25 117. 

In 1971 the National Academy of Science published a 40-page report, Asbestos The Need for and Feasibility of Air Pollution Controls, (Cooper, 1971) summarizing the illnesses associated with occupational exposure to asbestos and the risks of developing asbestosis, pleural calcifications, and cancers of the pulmonary and gastrointestinal tracts and thoracic cavity. Based on the evidence, the committee recommended control and reduction of dust containing fibrous inorganic materials in the workplace it also discussed nonoccupational exposure to asbestos. 

Specific regulations exist for the transport of asbestos materials by highway [53]. Asbestos must be loaded, handled, and unloaded using procedures that minimize occupational exposure to airborne asbestos particles released in association with transportation. Any asbestos contamination of transport vehicles also must be removed using such procedures (49 CFR 177.844). Additional motor carrier s safely regulations apply to common, contract, and private carriers of property by motor vehicle, as defined under these regulations (49 CFR Parts 390-397). 

National Institute for Occupational Safety and Health, US Department of Health, Education, and Welfare Criteria for a Recommended Standard... Occupational Exposure to Asbestos. DHEW (HSM) 72-10267. Washington, DC, US Government Printing Office, 1972... 

Cases of mesothelioma have been reported in adults who had no occupational exposure to asbestos, but who lived with a parent, spouse, or sibling who was an asbestos worker and presumably carried asbestos home on the work clothes (Anderson et al. 1976 Inase et al. 1991 Magee et al. 1986 Magnani et al. 

McDonald and McDonald 1980 Voisin et al. 1994). As with other asbestos-related respiratory health effects, asbestos-induced mesothelioma appears to have a long latent period of development. For example, Anderson et al. (1976) described two cases of women who presumably experienced household contact with asbestos as children, when their fathers worked with asbestos, and developed clinically detected pleural mesothelioma more than 30 years later. In a review of 1,105 cases of malignant mesotheliomas associated with occupational exposure to asbestos, Lanphear and Buncher (1992) reported that 99% had a latent period >15 years, and calculated a median latent period of 32 years. 

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