In vitro assays for detecting carcinogenic mineral fibres: a comparison of two assays and the role of fibre size.

The activities of 13 carcinogenic fibrous dust samples were compared in two in vitro test systems using V79/4 and A549 cells. Eleven of the dusts had similar ranks in both assays but two samples had disparate results. The relationship between the fibre length and diameter distributions of 12 of the samples and their activity in each assay was examined. A significant association between fibre length and biological activity occurred in both assays. This relationship showed increasing strength of association with increasing fibre length. The only significant association between fibre diameter and activity in vitro was demonstrated with fibres greater than 0.2 micron in the A549 assay.