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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