Mortality from specific causes among silicotic subjects: a historical prospective study

A historical mortality study was conducted among 520 silicotic subjects diagnosed at the Department of Occupational Health of the San Martino Hospital, Genoa, Italy, between 1961 and 1980. Vital status was ascertained as of 1 January 1982. Age-, sex- and calendar-year-adjusted standardized mortality ratios (SMRs) for specific causes were computed using Italian as well as Genoa County male population death rates. The study shows statistically significant increased mortality from all deaths (SMR = 2.92), all cancers (SMR = 2.38), respiratory tract cancers (SMR = 6.85), respiratory tract diseases (SMR = 13.63), and from 'other diseases' (SMR = 6.81). The excess mortality from respiratory tract diseases and from 'other diseases' are mainly attributable to silicosis and silicotuberculosis, respectively. These findings confirm the existence of a causal association between silicosis and increased mortality from both malignant and non-malignant respiratory tract diseases. The high mortality from respiratory tract cancers was still present even after adjustment for smoking.