Late progression of radiographic changes in Canari chrysotile mine and mill exworkers

The present radiological status of 133 exworkers (mean age: 58 +/- 0.7 yr) of the chrysotile mine of Canari (Corsica) was compared to that recorded in 1965, when the mine was closed. The mean time since first exposure is 27 +/- 0.4 yr, and the mean time since termination of asbestos exposure equals 16 +/- 0.3 yr. This study showed an evolution of radiographic changes: in 1965 only 14% of the subjects had grade 1/1 or more parenchymal fibrosis, and 6% had bilateral pleural lesions; in 1979 these percentages reached 40% and 27%, respectively. Subjects who had a given parenchymal change in 1965 (e.g., 1/1 grade lesions) were older and had a more intensive dust exposure and tobacco consumption than exminers who developed the same parenchymal changes much later. A progression of parenchymal changes was observed in 39% of the subjects with normal findings in 1965, and in 63% of the subjects with grade 1/1 or more changes in 1965. Those who progressed (46% of the cohort) were older, had a longer exposure, and a more intensive dust exposure and cigarette smoking than nonprogressors.