Raw cement asbestos (RCA) undergoes a complete solid state transformation when heated at high temperatures (1200 °C). The secondary raw material produced after treatment (HT-CA) is composed of newly-formed crystals in place of the original asbestos fibres present in RCA. Our previous studies (1) showed that HT-CA treatment exerts cytotoxic effects of lower grade compared to RCA. In this study we found that RCA treatment of A549 epithelial cells increase inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release in the culture media in RCA cells compared to control and HT-CA cells. It is already known that the asbestos-induced inflammatory status may drive lung cells to the carcinogenesis (2), events sustained by iNOS expression and NO production that play a role in cell-mediated immune response in lung cells. Interestingly, HT-CA cell treatment reveals Fe content in cristallized instead of soluble form found in RCA that can be related to the significantly lower toxicity for inertized cement-asbestos. Our findings confirm that HT-CA can be considered a transformed phase exerting direct lower cytotoxic and inflammatory potential compared to RCA on biological systems. High-temperature RCA treatment could represent a safe approach for storing or recycling asbestos materials. Further studies are in progress to exclude any residual carcinogenicity in HT-CA matrix
