The effect of fibrous dusts on lung cells. In vitro study

The mechanism of toxicity of selected asbestos substitute mineral fibres was examined and compared to that of asbestos. Alveolar macrophages and type II cells were isolated from Fischer 344 rats and after 20 h cultivation various concentration of fibres alone (amosite, wollastonite, rockwool or glass fibres) or in combination with cigarette smoke were added to cells and the cultivation continued for another 24 h. After finishing the exposure the number of alkaline phosphatase positive type II cells was counted, the comet assay was used to detect DNA damage (strand breaks) in both cell types and ultrastructural changes were evaluated by transmission electron microscopy. The decrease of the number of alkaline positive type II cells was dose dependent in all cases. The number of DNA strand breaks (SBs) in both cell types was enhanced after exposure to all types of fiber, the enhancement was dose dependent, the highest level of SBs was observed after amosite exposure. The combined exposure to mineral fibres and cigarette smoke showed synergic effect on the level of SBs. Transmission electron microscopy showed that already 1 microg x cm(-2) amosite caused destruction of AM while other fibres were phagocytized.