Increases With Radiographic Asbestosis Not Statistically Significant

One interesting study is called, Airways Obstruction From Asbestos Exposure Effects of Asbestosis and Smoking by Kaye H

. Kilburn and Raphael H. Warshaw - CHEST October 1994 vol. 106 no. 4 1061-1070.Here is an excerpt: Abstract - bjective: To define the apparent steps in developing airways obstruction vs restrictive lung disease in men exposed to asbestos for more than 20 years who had never smoked vs cigarette smokers.Design: Physiologic signs of asbestosis were studied in cross-sectional age-matched groups of never, current, and ex-cigarette smoking workers.Setting and participants: The study included 8,720 asbestos-exposed construction and shipyard workers in the United States.Measurements: FVC, FEV1, FEF25-75, and FEF75-85 were measured by spirometry and total lung capacity (TLC) by planimetry of standard chest radiographs and adjusted for height, age, and duration of cigarette smoking and expressed as percentage of predicted. TLC minus FVC yielded RV. We compared means and mean residuals (measurement minus group mean) expiratory flows and lung volumes in 1,146 men with pulmonary asbestosis age matched to 1,146 without asbestosis who had similar durations of asbestos exposure and to 370 men without asbestos exposure. Next, flows and volumes were regressed against the International Labour Office (ILO) profusion scale of irregular opacities on chest radiographs (PIO) and the duration of asbestos exposure for 1,777 never smokers (NS), 4,550 current smokers, and 2,393 ex-smokers.

Results: Asbestos exposure in NS men decreased expiratory flows and increased TLCs compared with unexposed NS men. Further reductions in flows and FVC and increases RV/TLC with radiographic asbestosis were not statistically significant. As the PIO increased from 1/1 to 3/3, obstruction and air trapping increased significantly but TLC did not.Conclusions: Asbestos exposure reduced flows and produced air trapping after 20 years in workers who never smoked. Smoking increased these abnormalities.

Another interesting study is called, A new high resolution computed tomography scoring system for pulmonary fibrosis, pleural disease, and emphysema in patients with asbestos related disease. By Al Jarad, N, Wilkinson, P, Pearson, MC, Rudd, RM - Occupational and Environmental Medicine -BR. J. IND. MED.Vol. 49, no. 2, pp. 73-84. 1992. Here is an excerpt: The aim of this study was to describe a scoring system for high resolution computed tomographic (HRCT) scans analogous to the International Labour Office (ILO) scoring system for plain chest radiographs in patients with asbestos related disease. Interstitial fibrosis, pleural disease, and emphysema were scored, the reproducibility and the interobserver agreement using this scoring system were examined, and the extent of the various types of disease was correlated with measurements of lung function. It is concluded that the HRCT scoring system allows good inter and intraobserver agreement. The scores using the HRCT scoring system and the ILO scoring system for chest radiographs correlate with impairment of lung function to a similar extent.

Another interesting study is called, Asbestos Bodies and Mesothelioma by

J. Stumphius and P. B. Meyer - Ann Occup Hyg (1968) 11 (4): 283-293.Here is an excerpt: Abstract - The relation between exposure to asbestos and the occurrence of neoplasia is reviewed and it is concluded that the increasing use of asbestos will result in an increasing incidence of tumours. It is known that inhalation of asbestos fibres results in the formation of asbestos bodies in the lungs.Typical asbestos initiated tumourspleural and peritoneal mesotheliomawere found at an unusually high frequency in shipyard-workers. Only slight asbestos exposure had taken place in these cases. On the other hand the persons involved had been exposed to high concentrations of iron oxide (flame cutters and welders). Objects similar to asbestos bodies were found in their lungs. Originally it was thought that these were pseudo asbestos bodies, containing an iron oxide core, and it was suspected that pseudo asbestos bodies might play a part in the genesis of the tumours. Investigations carried out at TNO institutes showed that the kernel of the bodies contained asbestos of the amphibole type thus proving that they were not pseudo but normal asbestos bodies. The simultaneous exposure to low concentrations of asbestos and high concentrations of iron oxide raises the suspicion that iron oxide might be an important cofactor in the genesis of mesothelioma found in the shipyard-workers. Experiments with different types of asbestos and iron oxide, on animals, are considered to be highly desirable in order to verify or disprove this hypothesis.

If you found any of these excerpts interesting, please read the studies in their entirety.We all owe a debt of gratitude to these researchers for their hard work.

by:Mont Wrobleski

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