Biological effects in vitro of raw and thermally treated asbestos-containing materials.

Introduction. Asbestos cement, the main asbestos-containing material (ACM) manufactured in Italy in the past, is a health hazard whose elimination is a priority concern. Asbestos fibers can be transformed into potentially non-hazardous silicates by high-temperature treatment via complete solid-state transformation. Methods. In this study A549 human non-small cell lung cancer (NSCLC) cells were directly exposed to raw cement asbestos (RCA), chrysotile and cement asbestos subjected to an industrial process at 1200 °C (HT-CA) and raw comme rcial grey cement (GC) for 24 and 48h, or treated with conditioned culture medium up to 96 h. In our previous studies we demonstrated that the final product of heat treatment of cement asbestos was considerably more inert and had lower cytotoxic potential than the original asbestos material. However, to better evaluate the risks of interactions with the materials, further in vitro investigations were performed concerning fiber-cell superficial interactions by SEM-EDS investigations, immunohistochemical expression of cytokines p53, p53 homologue p73, TNF-related apoptosis-inducing ligand (TRAIL), and conditioned medium effects on cell viability. Results. Data showed more severe cytotoxic damage by raw cement-asbestos compared to the heat treated materials and different expressions of cytokines that exert critical role in regulating the cell response to asbestos-induced DNA damage. Conclusion. HT-CA asbestos underwent a full transformation exhibiting newly formed crystals in place of the original fibres present RCA. HT-CA can be considered a transformed phase exerting direct low cytotoxic potential compared to RCA. Different intracellular localization of cytokines may reflect an alteration of the functional p53-p73 network during DNA damage. These data should be taken in consideration for a safe recycling of the secondary raw material.