Genotoxicity studies on selected organosilicon compounds: in vitro assays

A series of 12 organosilicon compounds representing potential intermediates in the synthesis and degradation of polydimethylsiloxanes were evaluated for genotoxic potential with a battery of in vitro assays. Microbial assays included the Ames bacterial reverse mutation in Salmonella, mitotic gene conversion in Saccharomyces cerevisiae D4 and DNA repair in E. Coli pol A +/-. These assays were conducted with and without a metabolic activation system containing Aroclor 1254-induced rat-liver homogenate. Forward gene mutation, sister-chromatid exchange, DNA alkaline elution and chromosome aberration potential were evaluated in mouse lymphoma L5178Y tissue culture cells. The tissue culture assays were performed with and without metabolic activation mixture utilizing uninduced mouse-liver S-9. The use of this enzyme preparation was felt to more closely mimic the actual in vivo situation and to be more compatible with mouse cells employed in the assay. No evidence of gene mutation was observed. However, six of the 12 compounds evaluated demonstrated potential in vitro clastogenic (chromosome damaging) activity.