Silica exposure and silicosis among tin miners in China: exposure response analyses and risk assessment.
Zhuang-Z; Attfield-M; Chen-B; Gao-P; Wallace-W; Chen-W; Chen-J
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :39
A cohort study of 3010 miners employed at least 1 year during 1960 to 1965 in four Chinese tin mines was conducted to investigate the risk of silicosis and cumulative exposure to silica-containing dust. Historical Chinese total dust data, which were collected differently from American total dust sampling method, were used to create a facility/job title/calendar year exposure matrix. Each worker's work history was abstracted from the complete employment records in mine files. Silicosis diagnoses were based on 1963 Chinese pneumoconiosis Roentgen diagnostic criteria, which classified silicosis as suspected or stages I-III. Suspected cases were not counted as silicosis cases in this study. There were 1015 (33.7%) miners who developed silicosis at an average age of 48.3 years, with an average duration of 21.3 years after first exposure. The risk of silicosis was found to be strongly related to cumulative total dust (CTD) exposure, and it can be well fitted by the Weibull distribution, with the risk of silicosis less than 1% when CTD exposure was under 10 mg/m3-years, and the risk increasing to 68.7% when CTD exposure was 150 mg/m3-years. This study predicts approximately a 30% cumulative risk of silicosis of a 40-year lifetime exposure to these tin mine dusts at the Chinese total dust exposure standard of 2 mg/m3. Total dust exposure data also were converted to respirable free silica exposure estimates (which introduces additional uncertainty into the exposure estimates) for comparison with findings from other epidemiologic studies of silicosis. This showed that the results were similar to most, but not all, findings from other large-scale exposure-response studies.
Mining-industry; Miners; Tin-compounds; Silica-dusts; Silicosis; Respiratory-system-disorders; Pulmonary-system-disorders; Lung-disease; Epidemiology; Employee-exposure; Exposure-assessment; Exposure-levels; Risk-analysis; Risk-factors; Standards; Dose-response; Dust-exposure; Dust-sampling; Sampling-methods
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia