Industry and job-specific mortality after occupational exposure to silica dust

Occupational exposure to silica dust occurs in many workplaces and is well known to cause silicosis. However, the link between silica exposure, silicosis and other diseases is still disputed.

To evaluate cause-specific mortality in a cohort of Italian silicotics.

The cohort included 2034 male compensated for silicosis between 1943 and 1986, alive on 1 January 1987 and resident in the Latium region (Italy). Mortality follow-up was from 1987 to 2006. Vital status and death causes were ascertained from the regional mortality archive. Standardized mortality ratios (SMRs) were computed assuming a Poisson distribution of observed deaths.

Significant excess mortality was observed from all causes (SMR: 1.17, 95% CI: 1.11-1.24), cancer of trachea, bronchus and lung (SMR: 1.39, 95% CI: 1.17-1.64), cancer of larynx (SMR: 2.18, 95% CI: 1.32-3.60) and tuberculosis (SMR: 5.85, 95% CI: 3.03-11.30). Higher risks were observed for masons (lung cancer, SMR: 2.46, 95% CI: 1.65-3.66) and miners (larynx cancer, SMR: 5.31, 95% CI: 1.88-15.03). In a Poisson regression analysis, the relative risk of death from lung cancer and silicosis increased with silicosis severity and decreased in more recent compensation periods.

The excess mortality from respiratory tract cancers and other diseases detected among Italian workers compensated for silicosis confirms previous epidemiological findings.