A prospective study of lung cancer in a cohort of asbestos cement workers was performed 20 and 25 years after their initial exposure to asbestos (1332214). Radiography was carried out on 151 workers who were employed for 9 years or more at a factory that made asbestos cement pipe and board using chrysotile (12001295) and crocidolite (12001284) asbestos in Ontario, Canada. Workers were exposed for at least 12 months to a range of exposures to asbestos from less than 50 fiber year/milliliter (f-y/ml) to greater than 200f-y/ml. At 20 years after initial exposure to asbestos, radiograms for 143 workers were examined; 20 of them had asbestosis. The lung cancer standardized mortality ratio (SMR) for those without asbestosis at 20 years latency was 5.53. At 25 years after initial exposure, radiograms for 128 subjects were examined; 14 of them had asbestosis. The lung cancer SMR for those without asbestosis at 25 years latency was 5.81. This study was consistent with other epidemiological studies of asbestos exposed populations in a variety of exposure situations. The authors conclude that the risk of cancer is increased in those who have radiographically identifiable asbestosis, but it may also be increased in its absence.

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