Alkaline earth silicate (AES) wools: Evaluation of potential cyto-genotoxic and inflammatory effects on human respiratory cells.

Biosoluble AES wools are increasingly used since considered not hazardous, however, few toxicity studies are available. We evaluated cytotoxic, genotoxic-oxidative and inflammatory effects of two differently soluble AES wools, AES1 (high MgO percentage) and AES2 (high CaO percentage), on alveolar (A549) and bronchial (BEAS-2B) cells. Fiber dimensions and dissolution in cell media were evaluated by SEM analysis. Cell viability, LDH release, direct/oxidative DNA damage (fpg-comet assay) and IL-6, IL-8 and TNF-α release (ELISA), were analysed after 24 h exposure to 2-200 μg/ml. On A549 cells AES1 induced LDH release, slight direct DNA damage and oxidative DNA damage with very high IL-6 release at 100 μg/ml; AES2 induced higher DNA damage than AES1 and slight oxidative DNA damage. On BEAS-2B cells we found direct DNA damage (higher for AES1) and slight oxidative DNA damage (associated to slight increased IL-6 and IL-8 release for AES1). The higher genotoxicity of more soluble AES2 on A549 cells could be explained by higher respirable fibers % and fiber number/μg found after 24 h in RPMI-medium at 100 μg/ml. The higher membrane damage, oxidative DNA damage and inflammation induced by AES1 in A549 cells could be due to the higher DLG and silica percentage. These findings suggest further investigations on AES toxicity.