Am. J. Respir. Crit. Care Med., Vol 153, No. 2, 02 1996, 711-718.
Mineral fiber content of lungs in patients with mesothelioma seeking compensation in Quebec
A Dufresne, R Begin, A Churg and S Masse
Department of Occupational Health, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
Asbestos fibers (AF) and ferruginous bodies (FB) in lung parenchyma from 50
workers seeking compensation from the Workers' Compensation Board of Quebec
for pleural or peritoneal mesothelioma were analyzed using transmission
electron microscopy (TEM) equipped with energy- dispersive spectrometer
(EDS) and phase-contrast microscopy (PCM). These workers had been
occupationally exposed in mining and milling activities (12 were from
Asbestos Township and 11 from Thetford Mines) and 27 were from other types
of industry (asbestos factory, shipyard, etc.). For comparison, analyses of
lung tissue at autopsy were done in a group of 49 subjects from a reference
population. A 95% confidence interval upper limit of 540 AF < 5
microns/mg and a 95% confidence interval upper limit of 161 AF > or = 5
microns/mg dried lung tissue were found for the reference population.
Similarly, a concentration of FB of 142 FB/g constituted the upper limit of
detectable FB in the lungs of the reference population. Forty-eight of the
50 workers with mesothelioma had either a ferruginous body or total
asbestos fiber count greater than the 95% confidence interval for the
reference population; the remaining two had amosite and/or crocidolite
concentrations greater than the 95% confidence interval for the reference
population. The fiber types were different in the three groups, with the
lungs of workers from Thetford Mines containing only chrysotile and
tremolite, those from Asbestos Township containing chrysotile, tremolite,
amosite, and crocidolite, and those in other industries containing largely
amosite and crocidolite. We conclude that in this population of workers
seeking compensation for mesothelioma, fiber analysis confirmed
occupational asbestos exposure in every case. The fiber types responsible
for the tumors are probably different in the three different groups.
