Asbestos exposure: factors associated with excess cancer and respiratory disease mortality.

A cohort of 1075 men who completed their working lifetimes with an asbestos company, worked at a facility in the United States, and retired with a company pension during the period 1941--67 was updated for deaths through 1973. The average length of employment was 25 years, and all had been exposed to asbestos dust. Respiratory cancer and pneumoconiosis-pulmonary fibrosis mortalities were examined in relation to cumulative dust exposure and to other factors after taking into account cumulative dust exposure. Men who worked in the production of asbestos cement pipe exhibited a higher risk of respiratory cancer, as did men with some crocidolite asbestos exposure. Because these two groups overlap, we could not be certain that crocidolite asbestos was responsible for the increased risk. Men working in general plant maintenance displayed a striking lack of deaths due to pneumoconiosis-pulmonary fibrosis, as compared with production workers and with maintenance personnel assigned to specific departments. Five mesothelioma deaths were observed at age 65 and over. Three of these deaths occurred during the period 1970--3.