In vitro prediction of the pathogenicity of mineral dusts

Eight mineral dusts, of which 7 were fibrous, were tested in 3 in vitro systems. The dusts had previously been tested for their ability to produce mesotheliomata in rats. The in vivo and in vitro biological activities of these dusts are compared with the number and size of fibres they contain. It is concluded that all the in vitro systems would predict which dusts are pathogenic in vivo, and that both in vivo and in vitro biological activities are determined by the number of long, fine fibres.