Mutagenicity of industrial compounds. VII. Styrene and styrene oxide: II. Point mutations, chromosome aberrations and DNA repair induction analyses.

The possible genetic effects produced by styrene have been investigated by means of different methodologies in several biological organisms: (a) the induction of point mutation has been investigated in Salmonella typhimurium (reverse mutation), in the yeast Schizosaccharomyces pombe (forward mutation), both in vitro and in vivo, in the host-mediated assay of mice, and in the Chinese hamster cell line grown in vitro (V-79) (forward mutation); (b) the induction of chromosome mutation has been investigated in vivo, in mice, through the analysis of the presence of chromosome aberrations in bone marrow cells of treated animals; (c) the production of DNA (deoxyribonucleic acid) damage and the stimulation of DNA repair synthesis have been evaluated from measurements of unscheduled DNA synthesis in a heteroploid human cell line (EUE) and gene-conversion produced in the yeast Saccharomyces cerevisiae treated in vitro and in vivo (host-mediated assay). All the in vitro studies have been developed by the testing of the styrene in the presence of a metabolic activating system obtained with a mouse liver microsomal preparation. Styrene oxide, one of the in vivo metabolites of styrene with electrophilic properties towards DNA molecules, have also been tested in similar systems. Styrene was not mutagenic in all the systems tested; styrene oxide, on the contrary, was shown to be an active mutagen, independently of the genetic system under evaluation.