Occupational asbestos exposure, lung-fiber concentration and latency time in malignant mesothelioma.

Mineral fiber concentration in lung tissue was analyzed by scanning electron microscopy in 73 males with malignant mesothelioma and in 36 referents who died of cardio- or cerebrovascular diseases. The investigation showed apparent differences in the median lung-fiber concentration between occupational groups with different levels of asbestos exposure, as judged from their occupational history. Thus the mineral fiber content in human lung tissue provides a useful indicator of cumulative asbestos exposure. There was also a statistically significant difference between the median lung-fiber concentration among mesothelioma cases with unlikely or unknown occupational asbestos exposure and the reference group. The latency times in 42 of the cases with definite or probable occupational asbestos exposure showed a log-normal distribution with a median of 37 years and a range of 19-68 years. No statistically significant correlation was found between the logarithm of the latency time and the logarithm of the lung-fiber concentration.