Persistence of carcinogenic effect in intact progeny of mice treated transplacentally with 7,12-dimethylbenz[a]anthracene

A look beyond the priority: A systematic review of the genotoxic, mutagenic, and carcinogenic endpoints of non-priority PAHs

Knowledge of the toxic potential of polycyclic aromatic hydrocarbons (PAHs) has increased over time. Much of this knowledge is about the 16 United States - Environmental Protection Agency (US - EPA) priority PAHs; however, there are other US - EPA non-priority PAHs in the environment, whose toxic potential is underestimated. We conducted a systematic review of in vitro, in vivo, and in silico studies to assess the genotoxicity, mutagenicity, and carcinogenicity of 13 US - EPA non-priority parental PAHs present in the environment. Electronic databases, such as Science Direct, PubMed, Scopus, Google Scholar, and Web of Science, were used to search for research with selected terms without time restrictions. After analysis, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, 249 articles, published between 1946 and 2020, were selected and the quality assessment of these studies was performed. The results showed that 5-methylchrysene (5-MC), 7,12-dimethylbenz[a]anthracene (7,12-DMBA), cyclopenta[cd]pyrene (CPP), and dibenzo[al]pyrene (Db[al]P) were the most studied PAHs. Moreover, 5-MC, 7,12-DMBA, benz[j]aceanthrylene (B[j]A), CPP, anthanthrene (ANT), dibenzo[ae]pyrene (Db[ae]P), and Db[al]P have been reported to cause mutagenic effects and have been being associated with a risk of carcinogenicity. Retene (RET) and benzo[c]fluorene (B[c]F), the least studied compounds, showed evidence of a strong influence on the mutagenicity and carcinogenicity endpoints. Overall, this systematic review provided evidence of the genotoxic, mutagenic, and carcinogenic endpoints of US - EPA non-priority PAHs. However, further studies are needed to improve the future protocols of environmental analysis and risk assessment in severely exposed populations.

Promotion of skin tumors by 12-O-tetradecanoylphorbol-13-acetate in two generations of descendants of male mice exposed to X-ray irradiation

Progeny of outbred SHR male mice intact or exposed to a single dose of whole-body X-ray irradiation (4.2 Gy) was painted twice a week for 24 weeks from the age of 4 months with acetone or with acetone solution of 6.15 micrograms 12-O-tetradecanoylphorbol-13-acetate (TPA). The incidence and number of skin papillomas were monitored from 2 until 20 weeks after the last application of the promoter. Exposure to acetone was never followed by skin tumor development in the progeny of either irradiated or non-irradiated males. Two weeks after TPA treatment in the progeny of intact mice the incidence of skin tumors was 20.1% in males and 36.6% in females, and 20 weeks later it was 11.6% in males and 14.6% in females. The skin tumor incidence in the progeny of the irradiated male mice 2 and 20 weeks after the last painting was 75.0% and 67.5% in males, 50.0% and 42.5% in females, respectively. Some F1 offspring of the irradiated male mice were mated before the start of TPA treatment, and F2 progeny were exposed to acetone or TPA as F1. The incidence of skin papilloma 2 weeks after the last TPA painting was 57.8% in males and 40.0% in females, whereas at 20 weeks after the last exposure to promoter it was 53.3% and 35.6%, respectively. In the progeny of irradiated male mice there were more animals with multiple (> 4) skin papillomas than in the progeny of intact mice. Our data allow us to suggest that irradiation of males before mating increases the susceptibility of progeny of at least two generations to promoters of carcinogenesis due to persisting genome instability.

Increased multiplicity of lung adenomas in five generations of mice treated with benz(a)pyrene when pregnant

The effect of benz(a)pyrene (BP) given to female mice of A strain on the 18 and 19th days of pregnancy was studied in 5 consecutive generations. As expected there was a high incidence of lung tumours (TBA%) in the F1-generation of mice treated with BP (53.9 vs. 15.4% in control in females and 77.6 vs. 8.0% in control in males). The percentage of TBA was not increased (with one exception) in both males and females of F2-F5 generations which were not directly exposed to carcinogen. Tumor multiplicity increase occurred not only in the F1 generation of BP-treated mice but in both males and females of F2-F5 generations of mice which were not in direct contact with the carcinogen. This increase was statistically significant. There was a slight negative trend within F2-F5 generation of BP-treated mice which however was not significant. Thus the transgenerational carcinogenic effect manifested in a greater tumour multiplicity persisted for four unexposed generations.