Descriptive Epidemiology of Cancer of the Larynx in the Province of Torino, Italy

An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy

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.

Screening of autopsy populations for previous occupational exposure to asbestos

A screening procedure to select, in autopsy populations, subjects having a major likelihood of previous occupational exposure to asbestos is described. To test our necropsy population we searched for pleural plaques (PPs); the optical count of both lung asbestos bodies (ABs) and uncoated mineral fibers (UMFs) at least 10 microns in length was recorded. In the adult autopsy population studied in the Turin area, the predictive value given by a positive test for large-size PPs (mostly bilateral) was about 55%. This level of probability did not rise in relation to the AB counts, whereas an increase to over 75% was observed if more than 10,000 UMFs/g dry lung were present. In subjects without PPs or with small-size plaque lesions (mostly unilateral), predictive values of positive tests were 20 to 30% when ABs and UMFs were found to be below 100 and 10,000/g, respectively, and increased to approximately 40% if the AB count exceeded 500/g and to almost 70% for an UMF count above 100,000/g. In subjects without PPs or with small-size plaque lesions, the probability of being nonexposed was greater than 90% if neither ABs nor UMFs were found. This autopsy screening may be a reliable tool in selecting cases most probably related to occupational exposure.

Pleural plaques and risk of cancer in Turin, northwestern Italy. An autopsy study

The relationship between the occurrence of neoplastic diseases and the presence of pleural plaques was studied in a series of 1097 autopsies performed in Turin from the adult general population. In men, pleural plaques showed an association with the presence of laryngeal, pulmonary, esophageal, and colorectal cancer. Only cancer of the larynx was strongly related to the occurrence of such pleural changes. This autopsy investigation confirms previous observations by others based on x-ray findings, and suggests that pleural plaques may be regarded as risk indicators of possibly asbestos-related tumors in the general population.

Descriptive Epidemiology of Hodgkin's Disease in the Province of Torino, 1965-1971

Age-standardized incidence rates of Hodgkin's disease in the province of Torino in 1965-1971 were 2.81/100,000/year in males and 1.64 in females, i.e., somewhat lower than in urban areas of other industrialized countries. In the whole province, age-distribution for males was similar to previous findings elsewhere, with a young-adult peak at ages 25-34. However, in the city of Torino, males showed a first peak in the age-class 35-44, while in the rest of the province an infantile peak (0-14 years) was found. By dividing the latter area in suburbs and nonmetropolitan area, the infantile peak was confirmed only in the nonmetropolitan area. Females showed a different behavior: in the city of Torino there was a unimodal curve (peak in age-class 55-64), and in the rest of the province there was a bimodal curve with a first peak in age-class 15-24. These patterns have been analyzed in relation to the suggestion of a distribution by age of Hodgkin's disease following 3 types (nonindustrialized countries, urban areas of industrialized countries and rural areas of industrialized countries). No significant differences in the distribution of cases were found among the smallest geographical units considered (ULSs), in contrast with previous findings on cancer of the larynx and bladder, which showed marked geographical differences within the province of Torino.