The objectives of this study were: (1) to compare lung fibre concentration and dimensions found in two groups of former Quebec chrysotile miners (Asbestos and Thetford-Mines) and, (2) to investigate the relationship between lung-retained mineral fibre concentration and dimension (length, diameter, and aspect ratio) to severity of interstitial lung fibrosis (asbestosis) within these groups. / Lung fibre content was determined for 86 former employees of chrysotile mines and mills in two Quebec mining regions: Thetford-Mines and Asbestos (Jeffrey Mine). Six lung samples were selected for each subject from predetermined intrapulmonary sites. / In summary, the concentrations of tremolite for short (<5 mum) intermediate-length (5--10 mum) and long (>10mum) fibres were 4, 2, and 2 fold higher respectively among workers of Thetford-Mines than those from Asbestos. These differences were statistically significant between the two groups (p < 0.05 for all tremolite size categories). No consistent and biologically important difference was found among fibre dimensions in any of the size categories (p > 0.1 for all fibre types and size categories). These observations suggested that the much higher exposure in Thetford-Mines to asbestos fibres, tremolite fibres being more apparent, is the most plausible factor which may explain the higher incidence of lung diseases among the former miners and millers of Thetford-Mines. / Concentration of short (<5 mum) tremolite fibres was the best predictor of asbestosis severity in both mining groups (r = 0.44, p < 0.01 and r = 0.39 p < 0.01 for Thetford-Mines and Asbestos, respectively). Chrysotile fibre concentration showed a lower correlation with asbestosis severity among subjects from Thetford-Mines (r = 0.28, p < 0.1 and r = 0.39, p < 0.01 and for fibres <5 mum and fibres 5--10 mum respectively). Long (>10 mum) amosite fibre concentrations showed a linear relationship with asbestosis severity in the group of miners and millers from Asbestos (r = 0.5, p < 0.01). Shorter commercial amphibole concentrations did not show this relationship and these fibres were largely absent from the lungs of miners from Thetford-Mines. Concentration of asbestos bodies from lung digests was significantly associated with fibrosis for subjects from Thetford-Mines only (r = 0.3, p = 0.05). (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36666 |
| Date | January 2000 |
| Creators | Nayebzadeh, Ataollah. |
| Contributors | Dufresne, A. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Occupational Health.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001740467, proquestno: NQ64631, Theses scanned by UMI/ProQuest. |
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