Health risk of chrysotile revisited

Abstract

This review provides a basis for substantiating both kinetically and pathologically the differences between chrysotile and amphibole asbestos. Chrysotile, which is rapidly attacked by the acid environment of the macrophage, falls apart in the lung into short fibers and particles, while the amphibole asbestos persist creating a response to the fibrous structure of this mineral. Inhalation toxicity studies of chrysotile at non-lung overload conditions demonstrate that the long (>20 µm) fibers are rapidly cleared from the lung, are not translocated to the pleural cavity and do not initiate fibrogenic response. In contrast, long amphibole asbestos fibers persist, are quickly (within 7 d) translocated to the pleural cavity and result in interstitial fibrosis and pleural inflammation. Quantitative reviews of epidemiological studies of mineral fibers have determined the potency of chrysotile and amphibole asbestos for causing lung cancer and mesothelioma in relation to fiber type and have also differentiated between these two minerals. These studies have been reviewed in light of the frequent use of amphibole asbestos. As with other respirable particulates, there is evidence that heavy and prolonged exposure to chrysotile can produce lung cancer. The importance of the present and other similar reviews is that the studies they report show that low exposures to chrysotile do not present a detectable risk to health. Since total dose over time decides the likelihood of disease occurrence and progression, they also suggest that the risk of an adverse outcome may be low with even high exposures experienced over a short duration.

Asbestos-Related Research: First Objectivity then Conclusions

“…Statements and conclusions by Bernstein et al are supported by numerous self-references [41,55]. It has been commented, however, that Bernstein's experimental findings contradict results obtained by independent researchers and can only be explained by an aggressive pre-treatment of fibers, inducing faults and fragility in the fibers' structure, leading to their hydration and breaking [56].…”

“…Chrysotile was found to be even more carcinogenic than amphiboles in [60], where it was pointed out: "There was no evidence of either less carcinogenicity or less asbestosis in the groups exposed to chrysotile than those exposed to the amphiboles" [60]. Technical details of the study [60] were discussed in [55] but not this essential result. In [64], chrysotile asbestos produced far more lung fibrosis and pulmonary neoplasia than the amphiboles, which was explained by a relatively high fraction of fibers longer than 20 μm in the chrysotile dust used in this experiment [18].…”

“…It means that certain artificial fibers, proposed as asbestos substitutes, are more biopersistent than asbestos fiber. The study [57] was cited in [55]; but the results were not discussed.…”

Malignant Pleura Mesothelioma: Clinical Perspectives

“…Chrysotile, which is also known as white asbestos, compromise 95% of this asbestos group [8]. However, the oncogenic capability of chrysotile is questionable [8,28]. Of the amphiboles, amosite (brown asbestos) and crocidolite (blue asbestos) had the most industrial applications [8].…”

Detection of pleural plaques in workers exposed to inhalation of natural fluoro-edenite fibres

“…The relationship between asbestos exposure and respiratory disease has been studied extensively (7). Occupational exposure to asbestos is known to be associated with Detection of pleural plaques in workers exposed to inhalation of natural fluoro-edenite fibres VENERANDO pleural and lung diseases, including pleural plaques, pleurisy, fibrosis of the visceral pleura, rounded atelectasis, asbestosis, lung cancer and malignant mesothelioma (8).…”