One study is called, “Asbestos-induced pleural fibrosis and impaired lung function” by Schwartz D. A. ; Fuortes L. J. ; Galvin J. R. ; Burmeister L. F. ; Schmidt L. E. ; Leistikow B. N. ; Lamarte F. P. ; Merchant J. A. – The American review of respiratory disease 1990, vol. 141 (1), no2, pp. 321-326 – Here is an excerpt: “Abstract – To assess the clinical significance of asbestos-induced pleural fibrosis, we evaluated the relationship between radiographic evidence of pleural fibrosis and spirometric values in 1,211 sheet metal workers. Of those with pleural fibrosis (n=334), 78% had circumscribed plaques and 22% had diffuse pleural thickening involving the costophrenic angle. Factors that were found to be associated with the presence and type of pleural fibrosis included increased age (p<0.001), more years in the trade (p<0.0001), more years since first exposure to asbestos (p<0.0001), more pack-years of cigarette smoking (p<0.01), and the presence and degree of interstitial fibrosis (p<0.0001). After controlling for these potential confounders (age, years in the trade, latency, pack-years of smoking, and ILO profusion category), linear multivariate regression models demonstrated that both circumscribed plaques (p=0.007) and diffuse pleural thickening (p=0.008) were independently associated with decrements in FVC but not with decrements in the FEV1/FVC ratio. Furthermore, our data indicate that the effect of diffuse pleural thickening on decrements in FVC is approximately twice as great as that seen with circumscribed pleural plaques. We conclude that the presence and type of pleural fibrosis among asbestos-exposed workers is independently associated with a pattern of spirometry that is suggestive of an underlying restrictive defect in lung function.”
Another study is called, “Radiographic abnormalities among Finnish construction, shipyard and asbestos industry workers” by Koskinen K. (1) ; Zitting A. (1) ; Tossavainen A. (1) ; Rinne J.-P. (1) ; Roto P. (1) ; Kivekäs J. (1 2) ; Reijula K. (1) ; Huuskonen M. S. (1) – Scandinavian Journal of Work, Environment & Health 1998, vol. 24, no2, pp. 109-117 (30 ref.). Here is an excerpt: “Abstract – Objectives – The prevalence of asbestos-related radiographic abnormalities was surveyed among Finnish construction, shipyard, and asbestos industry workers. Methods The radiographic screening focused on active and retired workers who were under the age of 70 years and had been employed for at least 10 years in construction or for at least 1 year in shipyards or in the asbestos industry. In 1990-1992, 18 943 people participated in an X-ray examination of the lungs and an interview on work history and exposure. The criteria for a positive radiological finding were (i) small irregular lung opacities clearly consistent with interstitial pulmonary fibrosis (ILO 1/1 or higher), (ii) lung opacities indicating mild pulmonary fibrosis (ILO 1/0) with unilateral or bilateral pleural plaques, (iii) marked adhesions with or without thickening of the visceral pleura, or (iv) findings consistent with bilateral pleural plaques. Results Fulfilling the criteria were 4133 workers (22%) (22% from construction, 16% from shipyards, and 24% from the asbestos industry). The radiological findings included signs of pulmonary fibrosis (3%), changes in the visceral pleura (7%), bilateral plaques (17%), and unilateral plaques (10%). Occupational disease was diagnosed according to the Finnish insurance regulations for three-fourths of those referred for further examinations, 96% being abnormalities in the pleura and 4% being asbestosis. Conclusions Exposure to asbestos dust has been common in ordinary construction work and, consequently, radiographic abnormalities (mostly pleural) occur frequently among active and retired construction workers.”
Another study is called, “Effects of cigarette smoke and asbestos on airway, vascular and mesothelial cell proliferation” – British Connective Tissue Society Meeting, London , ROYAUME-UNI – 1995, vol. 76, no 6, pp. A3-A57 (1 p.), pp. 411-418. by SEKHON H. ; WRIGHT J. ; CHURG A. Here is an excerpt: “Abstract – In order to determine whether exposure to both cigarette smoke and asbestos leads to enhanced cell proliferation, and whether pleura cell proliferation reflects the presence of fibres at or near the pleura, rats were exposed to air (control), daily cigarette smoke, a single intratracheal instillation of amosite asbestos, or a combination of smoke and asbestos. Dividing cells were labelled with bromodeoxyuridine (BrdU) and animals were sacrificed at 1, 2, 7 or 14 days. Both cigarette smoke and asbestos produced increases in the labelling index of small airway wall, epithelial cells and pulmonary artery cells. In the small airways there was a brief marked positive synergistic interaction between these two agents, but synergism was not seen in the vessels. Cigarette smoke did not increase the labelling of mesothelial or submesothelial cells, whereas asbestos caused a persisting increase in mesothelial cell labelling. There was no correlation between the number of BrdU labelled mesothelial or submesothelial cells and the number of fibres touching the pleura, or located within 180 ?m of the pleura. We conclude that the combination of cigarette smoke and asbestos exposure produces a complex set of interactions and has the potential to markedly increase cell proliferation in the parenchyma, an effect that may be important in both fibrogenesis and carcinogenesis. In contrast to the diminishing effects over time of a single dose of asbestos on cell proliferation in the small airways and vessels, the same dose of asbestos leads to sustained mesothelial cell proliferation. However, the latter process does not correlate with local accumulation of asbestos fibres.”
If you found any of these excerpts interesting, please read the studies in their entirety. We all owe a debt of gratitude to these fine researchers.
Tags: american review of respiratory disease, asbestos industry, cigarette smoking, clinical significance, fev1 fvc, finnish construction, interstitial fibrosis, multivariate regression models, pleural fibrosis, pleural plaques