Mean Durations of Asbestos Exposure and Chest Abnormalities

One interesting study is called, "Radiological abnormalities among sheet-metal workers in the construction industry in the United States and Canada : relationship to asbestos exposure" - INIST Diffusion - 2, Allée du Parc de Brabois F-54514 Vandoeuvre-lès-Nancy Cedex.  Here is an excerpt: "Abstract - We investigated the possible adverse health effects to sheet-metal workers who had past exposure to asbestos. A cross- sectional medical examination of 1330 workers was conducted during 1986 and 1987 in seven clities in the United States and Canada. A total of 1016 workers had been employed for at least 35 y in the industry, and the mean duration from onset of asbestos exposure was 39.5 y (SD=7.41 y). Chest x-ray abnormalities were found in more than half of the group. Pleural fibrosis, the most frequently found abnormality, was present in 47.0% of the cases and was the only abnormality found in 27.8% of cases; parenchymal interstitial fibrosis, found in 33.1% of cases, was the only abnormality found in 16.2% of cases."

Another interesting study is called, "Cancer Mortality Rate Among Workers in the Asbestos Industry of the Urals" by Kogan, F M, Guselnikova, N A, Gulevskaya, M R.  Here is an excerpt: "Based on a twenty year study of the mortality rate of workers in the mining of asbestos, it was found that the death rate was higher than among the rest of the population with reference to cancer of the lungs, stomach, intestines and cervix. A higher incidence of cancer was noted in the age group over 50; the mortality of women working with asbestos was found to be lower than the men in these areas, but considerably higher than among the female population. It is believed that a program of medical awareness should be instituted in work areas where people are employed in the mining, processing and use of asbestos, and that the achievement of low levels of dust in these areas would be a major factor in the lowering of cancer incidence of industrial workers."

Another interesting study is called, "The Evaluation Of Airborne Asbestos Fibres Using A Scanning Electron Microscope" By S. T. Beckett – Here is an excerpt: "Abstract - Asbestos fibres sampled on Nuclepore filters can be directly examined by scanning electron microscope in much greater detail than is possible using the conventional optical microscope/membrane filter technique. Results obtained by the two methods for fibres  5 in length were in good agreement. The new technique could facilitate the development of automatic counting methods for asbestos fibres."

Another interesting study is called, "Malignant vascular tumours of the pleura in "asbestos" workers and endothelial differentiation in malignant Mesothelioma" by R L Attanoosa, S K Suvarnab, E Rheadc, M Stephensc, T J Lockee, M N Sheppardd, F D Pooleyf, A R Gibbsa - Thorax 2000;55:860-863.  Here is an excerpt: "Abstract - BACKGROUND Three cases of diffuse malignant vascular tumours of the pleura are described which mimicked malignant mesothelioma clinically and pathologically (so called "pseudomesothelioma"). All had occupational histories of exposure to asbestos. The relationship of these tumours to mesothelioma and asbestos exposure is discussed.

METHODS To examine the histogenetic relationship between mesothelioma and these three tumours an immunohistochemical analysis of vascular marker (CD31, CD34, and Von Willebrand factor) expression was undertaken in 92 cases of pleural mesothelioma, in addition to these three tumours. Electron microscopic fibre analysis of lung tissue was performed on each of the three cases to assess asbestos fibre content.

RESULTS Diffuse pleural epithelioid haemangioendotheliomas may closely resemble malignant mesothelioma clinically and pathologically but, of the 92 pleural mesotheliomas tested, none showed expression of CD31, CD34, and Von Willebrand factor. Although all three cases had claimed exposure to asbestos, ferruginous bodies typical of asbestos were only seen by light microscopy in case 2, and only in this subject was the asbestos fibre content raised in comparison with the range seen in a non-exposed background population. The latent period in the pleural epithelioid haemangioendotheliomas ranged from 18 to 60 years.

CONCLUSIONS Endothelial differentiation does not appear to occur in mesothelioma and therefore should be clearly separated from it. No definite association between pleural epithelioid haemangioendothelioma and exposure to asbestos can be made from this small series but further investigation is warranted."

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