The in vitro induction of sister chromatid exchanges and chromosome aberrations in human lymphocytes by styrene derivatives.

Three structural analogues of styrene, vinyltoluene (40% para-, 60% meta -isomers), 4-methoxy-trans-beta-chlorostyrene and trans-beta-nitrostyrene, were tested for their potential to induce chromosome aberrations and sister chromatid exchanged (SCE) in phytohaemagglutinin-stimulated human lymphocytes cultured for 48 h (aberration analysis) or 72 h (SCE analysis). The treatments were carried out 24 h (aberrations) or 48 h (SCEs) before harvest. The toxicity of vinyltoluene to cultured lymphocytes was similar to that of styrene while 4-methoxy-beta-chlorostyrene was about 10 times and beta nitrostyrene about 100 times more toxic than styrene. A dose-dependent increase of SCEs and chromosome aberrations was observed in cells treated with vinyltoluene (0.33-4.00 mM) or with 4-methoxy-beta-chlorostyrene (0.5-1.00 mM). No effect could be seen in cultures treated with beta-nitrostyrene (0.004-0.044 mM). The results suggest that, like styrene, vinyltoluene and 4-methoxy-beta-chlorostyrene also are converted in vitro in reactive metabolites, presumably epoxides.