MICRONUCLEUS FORMATION IN V79 CELLS TREATED WITH RESPIRABLE SILICA DISPERSED IN MEDIUM AND IN SIMULATED PULMONARY SURFACTANT

Chinese hamster lung fibroblasts (V79 cells) were challenged with resp irable silica particles using an in vitro genotoxicity assay. Two part icle sizes of crystalline quartz and a non-crystalline silica were ass ayed for induction of micronuclei (MN) in V79 cells. Some of the silic a dusts used were pretreated with simulated pulmonary surfactant to mo del in vivo exposure conditions. The results showed that both crystall ine and non-crystalline silica dispersed in medium (MEM) induced MN fo rmation in a dose-dependent manner. Crystalline silica was more active in this assay than non-crystalline silica on a mass basis. The result s also show that the frequency of micronucleated cells in cultures tre ated with surfactant-coated silica was not significantly different fro m that of the non-treated control cultures. These results seem to indi cate that silica can cause chromosomal aberrations and/or aneuploidies in V79 cells; however, pretreatment of silica particles with simulate d pulmonary surfactant reduces or delays genotoxicity in this assay.