Further evidence for a link between silica dust and esophageal cancer

Abstract

Our objective was to examine the relationship between silicosis and esophageal cancer in Hong Kong. The mortality of esophageal cancer was investigated among caisson and non-caisson workers in a cohort of 2,789 male silicotic workers in Hong Kong during the period 1981-99. The standardized mortality ratio (SMR) was calculated using the Hong Kong general population rates as reference. The indirect method proposed by Axelson was used to adjust for the confounding effects of cigarette smoking and alcohol drinking. The SMR of esophageal cancer in the entire cohort was 2.22 (95% CI 1.36 -3.43, based on 20 deaths) and was 4.21 (95% CI 1.81-8.30, based on 8 deaths) in the subgroup of caisson workers who had a higher exposure to silica dust. The relative risk of esophageal cancer for caisson silicotics was reduced to 2.34 after adjusting for the effects of smoking and alcohol drinking. No more excess risk of esophageal cancer was observed among non-caisson silicotic workers after the adjustments. This historical cohort study revealed that there was an increased mortality risk of esophageal cancer among silicotics who had worked in underground caissons in Hong Kong after adjusting for cigarette smoking and alcohol drinking. We believe that the excess risk of esophageal cancer mortality among caisson workers with silicosis could best be explained by the very heavy exposure to free silica dust in their working environment.

Occupational exposures and risk of oesophageal cancer by histological type: a case–control study in eastern Spain

“…Other studies have also found an association with silica dust, which may give some support to our results 24 – 26. Whether the increase in risk of OC for this occupational group is real or not (ie, is due to incomplete control of the confounders tobacco smoking and alcohol drinking) is a question that should be clarified by further studies.…”

Environmental Causes of Esophageal Cancer

“…However, several studies have suggested that occupational exposure to asbestos could increase EC risk between 2-fold and 16-fold [241–245]. Other studies have found increased EC risk in relation to occupational exposure to silica [246–249]. However, other studies have shown no or only very slight increased risk with these occupational exposures.…”

Time trends of esophageal cancer in Hong Kong: Age, period and birth cohort analyses

“…Other risk factors, such as Barrett's esophagus and occupational exposure to silica dust, 8,33 are likely in the etiology of esophageal cancer. However, to date, evidence on these aspects is very sparse and in demand.…”