Lung mineral fibers of former miners and millers from Thetford-Mines and Asbestos regions: A comparative study of fiber concentration and dimension

Fiber dimension and concentration may vary substantially between two necrop sy populations of former chrysotile miners and millers of Thetford-Mines an d Asbestos regions. This possibility could explain, at least in part, the h igher incidence of respiratory diseases among workers from Thetford-Mines t han among workers from the Asbestos region. The authors used a transmission electron microscope, equipped with an x-ray energy-dispersive spectrometer , to analyze lung mineral fibers of 86 subjects from the two mining regions and to classify fiber sizes into three categories. The most consistent dif ference was the higher concentration of tremolite in lung tissues of worker s from Thetford-Mines, compared with workers from the Asbestos region. Amos ite and crocidolite were also detected in lung tissues of several workers f rom the Asbestos region. No consistent and biologically important differenc e was found for fiber dimension; therefore, fiber dimension does not seem t o be a factor that accounts for the difference in incidence of respiratory diseases between the two groups. The greater incidence of respiratory disea ses among workers of Thetford-Mines can be explained by the fact that they had greater exposure to fibers than did workers at the Asbestos region. Amo ng the mineral fibers studied, retention of tremolite fibers was most appar ent.