In vivo mutagenicity assessment of styrene in MutaMouse liver and lung

Abstract

Background Styrene (CAS 100-42-5) is widely used as polystyrene and acrylonitrile–butadiene–styrene resin such as plastic, rubber, and paint. One of the primary uses of styrene is food utensils and containers, but a small amount of styrene transferred into food can be ingested by eating. Styrene is metabolized into styrene 7,8-oxide (SO). SO is mutagenic in bacteria and mouse lymphoma assays. It is clastogenic in cultured mammalian cells. However, styrene and SO are not clastogenic/aneugenic in rodents, and no rodent in vivo gene mutation studies were identified. Methods To investigate the mutagenicity of orally administered styrene, we used the transgenic rodent gene mutation assay to perform an in vivo mutagenicity test (OECD TG488). The transgenic MutaMouse was given styrene orally at doses of 0 (corn oil; negative control), 75, 150, and 300 mg/kg/day for 28 days, and mutant frequencies (MFs) were determined using the lacZ assay in the liver and lung (five male mice/group). Results There were no significant differences in the MFs of the liver and lung up to 300 mg/kg/day (close to maximum tolerable dose (MTD)), when one animal with extremely high MFs that were attributed to an incidental clonal mutation was omitted. Positive and negative controls produced the expected results. Conclusions These findings show that styrene is not mutagenic in the liver and lung of MutaMouse under this experimental condition.

Lack of in vivo mutagenicity of carbendazim in the liver and glandular stomach of MutaMice

“…Genomic DNA was isolated from the tissues of five animals in each group in ascending order of animal ID as described previously [ 76 ]. Briefly, frozen tissue was homogenized using a pestle in Dounce buffer and the homogenized tissue was transferred to an ice-cold centrifuge tube containing 0.5 mol/L sucrose.…”

“…A lacZ mutation assay was performed as previously described [ 76 ]. Briefly, a mixture of E. coli C ( lacZ − , gal E − ) cell suspension and the total packaged sample were incubated for 30 min.…”