A possible mechanism of chrysotile asbestos toxicity

In vitro evaluations of heat treated and/or irradiated chrysotile asbestos indicate the importance of electron transfer in determining the biological outcome of asbestos exposure. Regardless of the assay system used, all show the same trends. Namely, heat treatment reduces cytotoxicity while heat treatment in combination with irradiation increases activity over heat treatment alone. Furthermore, studies of BSA and DNA binding consistently indicate a lower molecular adsorption for heated asbestos. BSA and DNA adsorption are similar for untreated, irradiated and heated or irradiated samples. Physical and chemical analyses indicate that the size and elemental composition are unaffected by the treatment processes. X-ray diffraction indicates no change in the crystal structure of chrysotile asbestos. IR spectroscopy suggests that heat treatment affects the external hydroxyl group population while heat treatment and irradiation may repopulate this functional group. A proposed mechanism consistent with the biological and physical characterization is based upon electron transfer from the chrysotile asbestos matrix to biological receptors.