Abstract

Since the beginning of 1972, we have followed a group of workers in an asbestos plant in Chongqing, China. In the plant, chrysotile has been used to manufacture asbestos textile, asbestos cement, flooring materials, friction materials, etc. Previously, we performed a matched (1:5) case-control study by selecting cases of workers who developed lung cancer sometime between 1975 and 2001 and found the elevated risk of lung cancer associated with the exposure. In 2006, we summarised further follow-up results of the cohort and found that, in addition to the 132 deaths until the end of 25th year, 101 workers were deceased during the last 10 years, and among them, 29 were from lung cancer (total: 51 lung cancers during the 35 years). Depending on the concentration of fibre of their workplace, we divided the workers into three levels of exposure. Compared to those in the administration and asbestos cement sections, workers in raw material and textile departments showed a higher HR for lung cancer (3.9, 95% CI 1.8 to 8.5) in Cox proportional hazard model analysis. Similarly, HRs for total cancer and total death were 2.0 (1.2 to 3.3) and 1.5 (1.1 to 2.0), respectively. Multivariate analysis controlling for age, smoking, and working time did not change the results greatly. The results of the present study confirm the strong association of chrysotile exposure and lung cancer. Results of the fibre type analysis of asbestos would be presented.