Nested case-control study of esophageal cancer in relation to occupational exposure to silica and other dusts

Background Standardized proportionate mortality ratio (SPMR) was found to be 2.2 (95% CI = 1.3-3.5)for esophageal cancer (EC) among workers exposed to refractory brick dust in a large iron-steel complex in China. Methods A nested case-control design within a cohort of industrial workers. One hundred and twenty-five EC cases and 250 control's were identified from the death registry file. Interviews were conducted of the next of kin for past exposure information on job, domestic, and lifestyle factors. History of occupational exposure to various dusts was reconstructed from personnel files and by interviewing colleagues utilizing a job-exposure matrix. Results After adjusting for confounders, occupational exposure to silica dust was the most important risk factor among all variables investigated, with a 2.8-fold risk and a clear dose-response by length of exposure. Alcohol drinking (OR = 1.8) and coal cooking (OR = 2.0) were risk factors and high consumption of fruit diet (OR = 0.5) and meat diet (OR = 0.6) were protective factors. Conclusions The relationship between occupational exposure to silica dust and the risk of EC found in an earlier SPMR study was confirmed. Ingestion of silica particles after lung clearance may increase the risk of EC among workers exposed to silica. (C) 1999 Wiley-Liss, Inc.