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Understanding Chrysotile Asbestos: A New perspective Based upon Current Data

David M. Bernstein, Consultant in Toxicology, Geneva, Switzerland, davidb@itox.ch

Recent publications have shown for synthetic mineral fibers that if a fiber dissolves rapidly and disappears from the lung, it does not cause a carcinogenic effect. With asbestos, chrysotile asbestos is often included with other asbestos materials. However, chrysotile is a serpentine mineral with markedly different mineralogical characteristics than amphibole asbestos (e.g. amosite, tremolite). These differences are mirrored in the differences in biopersistence between these two minerals. Chrysotile clears very rapidly from the lung with half-times ranging from 0.3 to 11 days and produces no inflammatory reaction. In contrast, the amphiboles clear with half-times in the range of 500 days or longer and produce a pronounced inflammatory response leading to mild interstitial fibrosis. These findings provide an important basis for substantiating both kinetically and pathologically the differences between chrysotile and amphiboles. In contrast to amphiboles, the toxicology of chrysotile can be understood in comparison to non-fibrous mineral dusts. These results fully support the differentiation of chrysotile from amphiboles reported in recent evaluations of available epidemiological studies.

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