No abstract

The mutagenic/carcinogenic activities of DEHP and MEHP were studied in bacteria and mammalian cells. MEHP but not DEHP exerted a dose-dependent DNA damaging effect to B. subtilis in Rec-assay. DEHP and MEHP showed mutagenic activities to S. typhimurium TA-100, with and without S-9 mix, respectively. MEHP produced not only the mutation in E. coli WP2B/r but also sister chromatid exchanges (SCE) in Chinese hamster V79 cells. It also induced 8AG/6TG-resistant gene mutations and chromosomal aberrations in the V79 cells. Transplacental administration of DEHP or MEHP to the Syrian golden hamster embryos was carried out by administering DEHP or MEHP to gravid animals on day 11 of gestation, followed by the cultivation of embryonic cells for 15-20 days. Both DEHP and MEHP induced 8AG/6TG-resistant mutation, chromosomal aberrations and morphological transformation in the embryonic cells of the Syrian golden hamster.ImagesFIGURE 3.

The genotoxic potential of acrylamide monomer (AA), a compound familiar as a raw material of polyacrylamide electrophoresis gel, was extensively investigated in vitro. The results were clear cut: AA did not induce any gene mutations in Salmonella/microsome test systems (TA98, TA100, TA1535, TA1537), Escherichia coli/microsome assay (WP2 uvrA-) up to a dose of 50 mg AA/plate, or in HPRT-locus in Chinese hamster V79H3 cells (AA, 1-7 mM, 24 h treatment). On the other hand, AA showed a strong positive response: (a) in a Bacillus subtilis spore-rec assay (DNA damage) at 10-50 mg/disc, (b) to a chromosomal structural change test (AA, 2-5 mM, 24 h treatment), (c) to a polyploidy test (AA, 1-5 mM, 24 h treatment) in Chinese hamster V79H3 cells, (d) to a cell transformation assay in mouse BALB/c3T3 cells (AA, 1-2 mM, 72 h treatment). Sister chromatid exchange was also weakly but significantly induced by AA (AA, 1-2.5 mM, 24 h treatment) in Chinese hamster V79H3 cells. Carcinogenic potential of AA was reported in mice and rats several years ago. AA thus seems to be a typical clastogenic rodent carcinogen without any gene mutation potential. Furthermore, this experiment showed for the first time positive response of AA to a microbial test system (B. subtilis spore-rec assay).

No abstract

Application of potent skin carcinogens, such as 7,12-dimethylbenz[a]anthracene, 3-methylcholanthrene, benzo[a]pyrene and 4-nitroquinoline-1-oxide, induced numerous dihydroxyphenylalanine (dopa)-positive cells in the interfollicular epidermis of C57BL/6 mice in a dose- and time-dependent fashion. Chrysene, a weak skin carcinogen, and croton oil, a tumor promoter, also induced 3--4 times more dopa-positive cells than acetone. Liver carcinogens, such as 3'-methyl-4-dimethylaminoazobenzene and N-2-acetylaminofluorene, and non-carcinogenic aromatic hydrocarbons, such as anthracene, fluoranthene, fluorene and pyrene, did not induce increase in these cells. These results indicate that increase in the number of dopa-positive cells after application of chemicals is well correlated with the abilities of these compounds to induce skin carcinogenesis and suppress sebaceous glands.