Study On Genotoxicity In Mice Of Joint Exposure To Formaldehyde And Benzene

Objective:Excessive indoor decorating or inferior building and furnishing materials greatly increased the indoor air pollution. Formaldehyde and benzene are volatile organic compounds, coexisted in various pollution sources, which have become the main pollutants of indoor air. Both have high levels of pollution, biological toxicity and mutagenicity, so people pay more attention to the health hazards caused by them. Now there are few studies on the joint toxicity of formaldehyde and benzene, especially the reports of joint genotoxicity. This study is to explore the genotoxicity and their mechanism in mice of single and joint inhaling formaldehyde and benzene, to provide the theoretical reference for health effects caused by indoor air polution.Methods:The 60 healthy and clean Kunming inbred strain male mice were as the research object were randomly divided into 10 groups. The mice in formaldehyde treatment groups were exposed at doses of 1 mg/m3,3 mg/m3,5 mg/m3; the mice in benzene treatment groups were exposed at doses of 500mg/m3,1500mg/m3,2500 mg/m3; the mice in formaldehyde and benzene treatment groups were exposed at doses of 0.5+250mg/m3,1.5+750mg/m3,2.5+1250mg/m3; the negative control groups were exposed at clean air. The treatments were conducted by static inhaling for two consecutive weeks, two hours a day. During the experiment, there are no food and water for the mice, other times freely eating and drinking. On 15th day, the mice were killed by infusing ice normal saline to the heart, to ensure that there was no blood in the body of mouse, then took out of the liver and marrow quickly. At the end, the coefficient of DNA-protein crosslink (DPC), the activity of superoxide dismutase (SOD), the contents of maleic dialdehyde (MDA) in livers of the mice were determined; the damage of marrow cells were observed.Results:â‘ The coefficient of DPC of liver of mice in moderate and high dose of formaldehyde or benzene exposure groups and each dose group of joint exposure groups were much higher than in the negative control groups(P<0.05),it aggravate as the dose increasing; The coefficient of DPC in moderate and high dose groups of joint exposure were much higher compared with the single groups (P<0.05).â‘¡The activity of SOD of liver of mice in each dose group of formaldehyde or benzene exposure groups and joint exposure groups were much lower compared with the negative control group (P<0.05), and the contents of MDA were much higher (P<0.05); they aggravate with the dose increasing. Compared with the single groups, the activity of SOD in each dose group of the joint exposure groups were much lower (P<0.05)and the contents of MDA were much higher (P<0.05).â‘¢Micronucleus rate of bone-marrow cells of mice in each dose group of formaldehyde or benzene exposure groups and joint exposure groups were much higher compared with the negative control group (P<0.05); Compared with single exposure groups, the micronucleus rate of each dose group of the joint exposure groups were much higher(P<0.05).â‘£Compared with the negative control group, tail DNA% and tail moment of bone-marrow cells of mice in each dose group of formaldehyde or benzene exposure groups and joint exposure groups were much higher(P<0.05); Compared with single exposure groups, the tail DNA% and tail moment in the low dose group and the moderate dose group of the joint exposure groups were much higher(P<0.05); The tail DNA% and tail moment in the high dose group of the joint exposure groups were much higher compared with single high dose group of formaldehyde (P<0.05),but not single high dose group of benzene.Conclusion:Formaldehyde and benzene had genotoxicity in mice of single or joint exposure. They could induce the DPC of liver cells, cause lipid peroxidation damage of liver tissue, result in DNA damage of bone-marrow cells. The joint genotoxicity of formaldehyde and benzene on the mice is more serious compared with a single exposure. Maybe the joint genotoxicity effect is synergistic. The DPC, lipid peroxidation damage and DNA breakage might be the important mechanisms of genetic damage in mice induced by formaldehyde and benzene.