Closing the knowledge gap on the composition of the asbestos bodies

摘要

Asbestos bodies(AB)form in the lungs as a result of a biomineralization process initiated by the alveolar macrophages in the attempt to remove asbestos.During this process,organic and inorganic material deposit on the foreign fibers forming a Fe-rich coating.The AB start to form in months,thus quickly becoming the actual interface between asbes-tos and the lung tissue.Therefore,revealing their composition,and,in particular,the chemical form of Fe,which is the major component of the AB,is essential to assess their possible role in the patho-genesis of asbestos-related diseases.In this work we report the result of the first x-ray diffraction measure-ments performed on single AB embedded in the lungtissue samples of former asbestos plant workers.The combination with x-ray absorption spectroscopy data allowed to unambiguously reveal that Fe is present in the AB in the form of two Fe-oxy(hydroxides):ferri-hydrite and goethite.The presence of goethite,which can be explained in terms of the transformation of fer-rihydrite(a metastable phase)due to the acidic con-ditions induced by the alveolar macrophages in their attempt to phagocytose the fibers,has toxicological implications that are discussed in the paper.