Some observations on the in vitro cytotoxicity of chrysotile prepared by the wet dispersion process

Samples of the chrysotile taken during and after treatment by the wet dispersion process have been tested for their cytotoxic effect in vitro and the results compared with both a UICC chrysotile A sample and a dust prepared from a standard chrysotile textile yarn. Results were obtained from three different in vitro assay systems utilizing P388D1, V79-4 and A549 cells. A sample which still contained the wetting agent used in the wet dispersion process failed to show activity in any of these assays. The other samples, however, were all active with those dusts obtained by milling the final product and by sampling the air of the factory consistently proving significantly more cytotoxic than the standard chrysotile controls. Preliminary results from a parallel in vivo study suggest that these samples are also more active in producing mesotheliomas in rats.