Studies on the relationship between treatment condition and micronucleus induction in V79 cells exposed to silica and glass fibers

Abstract

Studies have been carried out to determine the relationship between treatment condition and frequencies of micronucleated cells (MNC) and multinucleated cells (MTC) in Chinese hamster lung fibroblasts (V79 cells) exposed to dusts and fibers. Cells were treated with Min-U-Sil 5 silica or Owens Corning AAA-10 glass fibers under three different conditions: 24-h exposure (24E), 24-h exposure followed by 24-h post-incubation in fresh medium (24E–24P), and 48-h exposure (48E). Results showed that the frequency of MNC increased in a concentration-related manner in silica-treated V79 cells only under the condition of 24E–24P. The increase in MNC frequency after 24-h exposure was not concentration-related. No significant increase in MNC was detected in cells sampled after 48-h treatment. The frequencies of MTC in the treatment groups were higher than that in the control group. However, the increase was not statistically significant. Compared with silica, glass fibers were more active for MTC and MNC induction on a mass basis. The highest response was also observed under the condition of 24E–24P. These results indicate that 24-h exposure followed by 24-h post-incubation is a suitable treatment condition for the micronucleus assay on mineral dusts and fibers.