The mortality experience of a cohort of
chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (
hepatic cirrhosis, accidents). For mortality from
cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for
oral cancer (SMR 231 based on six deaths),
cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for
cancer of the larynx. Rates were not increased for lung, stomach, or any other type of
cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for
oral cancer, but the greatest risks for laryngeal and pleural
cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from
laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to
chrysotile asbestos (or to the fibre
balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of
laryngeal cancer and pleural
mesothelioma. The absence of excess mortality from
lung cancer in this cohort is difficult to interpret.