The Hazards of Chrysotile Asbestos. A Critical Review.

Abstract

Chrysotile, or "white", asbestos is the dominant form of asbestos in international commerce today. It accounts for 99% of current world asbestos production of 2 million tonnes. Chrysotile is an extremely hazardous material.Clinical and epidemiologic studies have established incontrovertibly that chrysotile causes cancer of the lung, malignant mesothelioma of the pleura and peritoneum, cancer of the larynx and certain gastrointestinal cancers. Chrysotile also causes asbestosis, a progressive fibrous disease of the lungs. Risk of these diseases increases with cumulative lifetime exposure to chrysotile and rises also with increasing time interval (latency) since first exposure.Comparative analyses have established that chrysotile is 2 to 4 times less potent than crocidolite asbestos in its ability to cause malignant mesothelioma, but of equal potency of causation of lung cancer. The International Agency for Research on Cancer of the World Health Organization has declared chrysotile asbestos a proven human carcinogen. Sales of chrysotile asbestos have virtually ended in Western Europe and North America, because of widespread recognition of its health hazards. However, asbestos sales remain strong in Japan, across Asia and in developing nations worldwide. The claim has been made that chrysotile asbestos can be used "safely" under "certain conditions" in those nations. That claim is not accurate. The Collegium Ramazzini, an international learned society in environmental and occupational medicine, has called for an immediate worldwide ban on all sales and uses of all forms of asbestos, including chrysotile. The rationale for this ban is threefold:(1) that safer substitute materials are readily available, (2) that "controlled" use of asbestos is not possible, and (3) that the health risks of asbestos are not acceptable in either the industrialized or the newly industrializing nations.

Asbestos Exposure in a Shipyard Area, Northeastern Italy.

“…More precise methods include the counting of the asbestos fibres and the identification of such fibres. This last point is of particular relevance, since the old question of the danger related to the chrysotile, continues to be discussed [14][15][16][17] . The identification of the type of asbestos has been performed only in a very limited sample of the present series and the results have previously been published 18) .…”

Asbestos-Related Research: First Objectivity then Conclusions

“…In certain animal experiments, the amphiboles and chrysotile were shown to be nearly equally carcinogenic for the induction of both Mt [50,58,60,61] and lung cancer [62,63]. 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].…”

“…However, in a later publication by the same authors, the proportion 1:5:10 is discussed; and it is acknowledged that recent evidence had strengthened the case for the proposition that the per-fiber risk of mesothelioma from chrysotile in textile plants is greater than it is in mines [89]. According to [46,62,63], there is no epidemiological or toxicological evidence that chrysotile is less potent than other forms of asbestos for induction of lung cancer, which is essential because of much higher prevalence of lung cancer. It has been suggested that the difference between chrysotile and amphibole fibers for lung cancer is between 1:10 and 1:50 [88].…”

“…In the author reply [71], the arguments from [67] have not been adequately responded, being dismissed by a declaration that the studies [68,69] "appear to support the concepts put forward by Bernstein et al" followed by self-references [71]. Other reports and reviews [43][44][45][46][47][48]51,56,58,63,[72][73][74][75], not supporting the authors' concept, are also not cited in the voluminous reviews [41,55]. Another example: Bernstein et al cite a rather nondescript phrase from the review "Mesothelioma from chrysotile asbestos" [55,76] that chrysotile is an "exclusive or overwhelming fiber exposure", disregarding the main conclusion: "Chrysotile asbestos, along with all other types of asbestos, has caused mesothelioma" [76].…”

Occupational Exposure to Asbestos During Renovation of Oil-Shale Fuelled Power Plants in Estonia

“…In many developed countries, in the most affected age groups, mesothelioma may account for 1% of all deaths and 5-7% of all lung cancers can be attributed to occupational exposure to asbestos. Besides low-level exposure may lead to asbestos-related diseases, although high exposure for long periods is linked more clearly to these illnesses [1,2,3,4].…”