Understanding Cellular and Enzyme Responses of Chrysotile Asbestos

Occupational exposure to asbestos causes the death of thousands of people each year.  This has led to an almost unparalleled body of research trying to better understand asbestos and its link to mesothelioma disease.  One interesting study is called, "Kinetics of the bronchoalveolar leucocyte response in rats during exposure to equal airborne mass concentrations of quartz, chrysotile asbestos, or titanium dioxide." by K Donaldson, R E Bolton, A Jones, G M Brown, M D Robertson, J Slight, H Cowie, and J M Davis - Thorax 1988;43:525-533.  Here is an excerpt: "Abstract - The kinetics of the bronchoalveolar response was assessed in rats exposed, at equal airborne mass concentration (10 mg/m3), to titanium dioxide--a non-pathogenic dust--and the two pathogenic mineral dusts quartz and chrysotile asbestos. Rats were killed at intervals over a 75 day exposure period and groups of rats exposed for 32 and 75 days after recovery for two months. Bronchoalveolar lavage was carried out and the lavage fluid characterised for cellular content, macrophage activation, and concentrations of free total protein, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase. Inhalation exposure to the two pathogenic dusts resulted in an increased number of leucocytes, macrophage activation, and increased levels of free enzymes and total protein. The pattern and magnitude of the responses to quartz and chrysotile differed. Chrysotile caused less inflammation than quartz, and the main cellular response peaked around the middle of the period of dust exposure whereas the highest levels of enzymes occurred towards the end. The difference in timing suggests that macrophages were not available for lavage towards the end of the exposure, owing to their playing a part possibly in deposition of granulation tissue. Quartz caused a greater cellular and enzyme response than chrysotile, particularly towards the end of the dust exposure phase. There was a noticeable progression of inflammation in the quartz exposed groups left to recover for two months, but not in the chrysotile recovery groups."

A second article that is interesting is called, "Chemical Characterization of Asbestos Body Cores by Electron Microprobe Analysis" by Arthur M. Langer, Ivan B. Rubin, and Irving J. Selikoff - Environmental Sciences Laboratory, Mount Sinai School of Medicine of the City University of New York, New York, New York 10029 - Journal of histochemistry and Cytochemistry May 18, 1972.  Here is an excerpt: "Inhalation of asbestos may be associated with increased risk of developing malignant neoplasms. Some of the fibers become coated in the lung, resulting in "asbestos bodies." The occurrence of structures with the appearance of asbestos bodies in the lungs of urban dwellers the world over, individuals with no known exposure to these mineral fibers, has raised the question of whether the community at large may also have increased risk of neoplasia as the result of chance environmental asbestos exposure. Since other fibrous materials may also sometimes become so coated, epidemiology evaluation of the presence of asbestos bodies has been hampered by difficulties in obtaining absolute identification of the cores of the bodies found. Five fibrous silicates, consisting of four amphiboles (amosite, anthophyllite, crocidolite and tremolite) and one serpentine (chrysotile), constitute the asbestos mineral group. Chemically, they are diverse enough for unique identification. The electron microprobe analyzer permits microchemical analysis of particles in the sublight microscopic size range. Analysis of asbestos body cores requires particle selection, extraction from tissue matrix, a suitable conducting substrate, proper coating material, selection of optimal instrumental operating conditions and comparison of unknown cores with known fiber standards. In this investigation, asbestos body cores have been analyzed from tissues obtained from occupationally exposed individuals (known fiber exposure), laboratory animals (known exposure) and individuals with no known occupational exposure. Cores of bodies have been analyzed as amosite, chrysotile, chemically degraded chrysotile and cores of undetermined nature. Amosite fibers as cores of asbestos bodies show no marked chemical degradation even after prolonged biologic residence, whereas chrysotile asbestos cores are markedly degraded. Cores of asbestos bodies from the general population, from individuals with no known exposure, may consist of degraded chrysotile, synthetic silicate fibers and, in some cases, amphibole asbestos."  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.