Biological in vitro and in vivo responses of chrysotile versus amphiboles.

Abstract

Although all commercial forms of asbestos have been demonstrated to be carcinogenic in animals, so far epidemiological data are controversial concerning what asbestos types are the most carcinogenic and fibrogenic in humans. In order to understand the early cellular events induced by fibrous particles, different in vitro studies (hemolysis, release of enzymes by macrophages, assays on cell culture systems) have been carried out in several laboratories; most of these studies have shown that cell and subcellular in vitro responses were different depending on fiber types: chrysotile versus amphiboles. This presentation compares the results of different laboratories with our data obtained by using a model which modifies the chemistry of the fibers by acid treatment. The acid-leached chrysotile and acid-treated amphibole fibers showed different biological responses in several in vitro systems used in comparison to unleached fibers. These differences in the in vitro reactivity were related to the chemical state of the fibers and might explain the differences in their effects in animals after intrapleural injection as assessed by the percentage of mesothelioma, the latency period, the survival time and the degree of pleural fibrosis. The carcinogenic effect of the fibers is discussed in relation of their in vitro inflammatory or cytotoxic responses.

Malignant pleural mesothelioma: history, controversy and future of a manmade epidemic

“…Based on epidemiological data, the long, thin amphiboles (crocidolite and amosite) have been regarded as the most carcinogenic, while the short and curly serpentines (chrysotile) are regarded as less dangerous, but undoubtedly carcinogenic. As noted previously, more recent data point out that chrysotile should probably not be considered less dangerous [74][75][76].…”

Medical examination for asbestos‐related disease

“…The commercial use of asbestos has resulted in the very wide distribution of asbestos in the environment. All types of asbestos ®ber are associated with the development of asbestos-related scarring [Bignon and Jaurand, 1983] and malignancies [Dement et al, 1983;Seidman et al, 1979;Wignall and Fox, 1982;Meurman et al, 1974;McDonald et al, 1997]. A debate has been evolving on the role of chrysotile in the causation of mesothelioma [Mossman et al, 1990;Nicholson, 1991;Harington, 1991;Huncharek, 1994;Churg 1993;Boffetta 1998].…”

What Every Surgeon Should Know regarding Asbestos-Related Disease

“…Fi bers o f a length o f 8-20 pm seem to be the most dangerous, but fibers up to 200 pm in length have been demonstrated in human lung tissue. The straight, more rigid amphibolc fibers are more likely to penetrate through the alveoli and persist longer than chrysotile [1], A small portion of fibers may become coated with an iron-containing protein and are re ferred to as 'asbestos bodies'. They are simply an indication o f exposure.…”