A retrospective mortality cohort study of chrysotile asbestos products workers in Tianjin 1972-1987

The mortality rate of a cohort of asbestos workers was investigated in Tianjin, China, between January 1, 1972, and December 31, 1987. The cohort consisted of 662 males and 510 females, employed in asbestos textiles, friction material, and asbestos cement manufacturing. A statistically significant excess mortality was observed for lung cancer in both males and females (SMR 278 and 427, respectively). An increasing trend in SMR was observed with increasing intervals of exposure as well as with increasing exposure level. A synergistic effect was seen between asbestos exposure and cigarette smoking regarding lung cancer. The ratio of smoking and nonsmoking lung cancer death rates was virtually the same in asbestos and in nonasbestos workers. This ratio was approximately 1.6, a value much less than that reported in other countries. This low ratio appears to reflect the fact that many nonsmokers were in fact passive cigarette smokers. Second, it reflects the fact that most smokers smoked hand-rolled tobacco, since manufactured cigarettes did not become popular in China until 1965. These data confirm the hazards of asbestos exposure in developing countries.