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.

A series of 1000 cases was selected, on the basis of a clinical and/or post-mortem diagnosis of cancer, out of 4927 autopsies performed at the Institute of Pathologic Anatomy and Histopathology of Turin University. The comparison between clinical and post-mortem diagnoses pointed to an overall concordance with regard to the correct identification of a malignancy as the underlying cause of death of 75%; if the correct identification of type and primary site of the tumor was also taken into account, the concordance was only 56%. The rate of false-positive and false-negative diagnoses, the confirmation rate and sensitivity index of clinical diagnoses, and the error of estimate of the overall frequency of the different types of tumors were computed. Pancreas, liver and biliary tract tumors appear to be the most difficult to identify correctly during life; also lung, stomach and colorectal cancers, lymphomas and leukemias show fairly high rate of clinical errors. Breast cancer, tumors of the nervous system and colorectal cancers appear to be overnotified. These results seem to underscore the necessity of being very careful in drawing conclusions on the frequency and distribution of the different types of cancer on the basis of current mortality statistics.

The lung concentration of coated and uncoated mineral fibres of more than 10 micron in length was determined by light microscopy in 57 autopsied subjects (23 out of which professionally exposed to asbestos) with pleural plaques but no other asbestos-related diseases. Comparisons were made with 57 controls matched for sex, age and smoking habits, who did not show any asbestos-associated diseases or history of previous occupational exposure. Subjects with pleural plaques had a median concentration of coated fibres consistently greater than that observed in those without. However, no substantial differences were found between the two studied groups when uncoated and total fibres were considered. The present study suggests that the factors related to the fibre coating and to the pleural plaque formation may be indirectly connected, but not necessarily restricted to the number and nature of the fibres, or to the professional or environmental conditions of exposure.