Short Crocidolite Fibers and Cell Injury from Asbestos
There is evidence that suggests that a high dose of exclusively short asbestos fibres produces minimal lung injury and fibrosis
. One interesting study is called, "Cytogenetic studies on chrysotile asbestos" by K. S. Lavappa1, M. M. Fu and S. S. Epstein - Environmental Research - Volume 10, Issue 2, October 1975, Pages 165-173. Here is an excerpt: "Abstract - The cytogenetic effects of chrysotile asbestos (chrysotile A) in vivo in Rhesus monkeys and Swiss albino mice, and in vitro in embryonic hamster cells were investigated. Single oral dosages of chrysotile, 100 or 500 mg/kg, failed to induce chromosome aberrations in bone marrow cells of Rhesus monkeys. Similarly, oral or intraperitoneal administration of chrysotile over a dose range from 0.4 to 400 mg/kg, failed to induce micronuclei formation in bone marrow cells of mice. However, chrysotile induced a significant and dose-related increase in chromosome aberrations and a dose-related inhibition of the mitotic index of cultured Syrian hamster embryo cells."Another interesting study is called, "Response of mouse lung to crocidolite asbestos. Minimal fibrotic reaction to short fibres" by Dr Ian Y. R. Adamson, Drummond H. Bowden - The Journal of Pathology - Volume 152, issue 2, pages 99-107 June 1987. Here is an excerpt: "Abstract - To determine the relationship between the development of pulmonary fibrosis and the size of deposited asbestos, we prepared a pure sample of short crocidolite fibres and instilled 0.5 mg of 0.1 mg to the lungs of mice. Animals were killed up to 20 weeks later with 3H thymidine injected 1 h before death. By bronchoalveolar lavage, there was a rapid transient increase in polymorph neutrophils (PMN) and in glucosaminidase levels; alveolar macrophage (AM) numbers were elevated in the 0.5 mg group for eight weeks. Most fibres were phagocytized by AM, many of which were heavily laden and cleared from the lung over the 20 week period. Some fibres were seen in type 1 epithelial cells, frequently associated with cell injury. From cell kinetic studies, a very brief proliferative response was seen in bronchiolar epithelial and Type 2 alveolar epithelial cells. A greater response was seen in interstitial fibroblasts which showed increased labelling up to two weeks after 0.5 mg asbestos. However no granulomas were seen and very little fibrosis was found by morphology or by biochemistry at any time after 0.5 mg; no fibrosis was seen after instilling 0.1 mg. The results show that a high dose of exclusively short asbestos fibres produces minimal lung injury and fibrosis in spite of long standing macrophage-fibre interaction in the alveoli."
Another interesting study is called, "Analysis of the cores of asbestos bodies from members of the general population: patients with probable low-degree exposure to asbestos" by Churg, A. ; Warnock, M.L. - Am. Rev. Respir. Dis.; (United States); Journal Volume: 120:4. Here is an excerpt: "Asbestos bodies were isolated from the lungs of 21 patients who had 300 to 9000 of such bodies/g of lung tissue, a concentration frequently found in manual laborers in the general population who are not primary asbestos workers. All of the 123 bodies examined by electron diffraction produced diffraction patterns consistent with amphibole varieties of asbestos. Electron microprobe analysis (energy dispersive x-ray spectroscopy) of 46 bodies revealed that 38 of the cores were composed of the commercial amphiboles, amosite and crocidolite, whereas only 8 were composed of the noncommercial amphiboles, anthophyllite and tremolite. Review of the occupations of these patients revealed that all but one had blue-collar jobs. We concluded that commercial amosite/crocidolite asbestos forms the cores of most asbestos bodies in manual laborers in the general population and that the source is usually occupational."
We all owe a debt of gratitude to these researchers. If you found any of these excerpts interesting, please read the studies in their entirety.
Short Crocidolite Fibers and Cell Injury from Asbestos
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