Study On Reproduction Toxicity In Male Mice Of Joint Exposure To Formaldehyde And Benzene

Objective: Recently, as indoor decorating becomes the trend of fashion, formaldehyde and benzene released by ornament materials have become the main pollutants of indoor air. Formaldehyde and benzene usually exist together indoors in high concentrations, so they can have combined toxic effect on human body. Now there are lots of reports about reproduction system function damage induced by formaldehyde or benzene, but few about reproduction toxicity of joint exposure to the two substances. This study is to explore the reproduction toxicity in male mice of joint exposure to formaldehyde and benzene, to provide scientific basis for the synthetic evaluation of formaldehyde and benzene security and theory reference for research on indoor pollutionMethods: The 156 KM male mice were randomly divided into 13 groups. The mice in formaldehyde treatment groups were exposed at doses of 0.2 mg/kg,2 mg/kg, 20 mg/kg,with sodium chloride injection(0.01 ml/g) as negative control group; the mice in benzene treatment groups were exposed at doses of 100.0mg/kg,200.0mg/kg,400.0mg/kg,with peanut oil(0.01 ml/g) as negative control group; the mice in formaldehyde and benzene treatment groups were exposed at doses of 0.1+50.0mg/kg,1 + 100.0mg/kg,10+200.0mg/kg, with sodium chloride injection(0.005ml/g) + peanut oil(0.005ml/g) as negative control group;cyclophosphamide solution dose was 40mg/kg as positive control group. The mice were exposed to formaldehyde and benzene by peritoneal injection for five days,once per day. On the sixth day, 6 mice selected randomly in every group were killed by femoral artery bloodletting, then the blood, the testicles and the epididymises were collected in order to measure the contents of Cu,Zn in the blood,testicles and observe the pathological changes of testicle tissues,the abnormal sperms. Meanwhile the rest mice were killed by cervical vertebra dislocation, then the testicles were collected so that the activities of SOD,the contents of MDA in testicles could be determined and the DNA damage in testicle cells could be observed.Results: (1) Some pathological damages existed in testicles of mice exposed to formaldehyde or benzene; the pathological damages in testicles of mice exposed to formaldehyde and benzene were more serious. (2) Compared with those in the negative control groups, the contents of Cu,Zn in the blood and testicles of mice in every exposure group were significantly decreased(P<0.05); the contents of Zn in the blood and the contents of Cu,Zn in testicles of mice in joint exposure groups were much lower than those in formaldehyde or benzene exposure groups(P<0.05). (3) The activities of SOD in testicles of mice in every exposure group were decreased more significantly than those in the negative control groups(P<0.05), while the contents of MDA were increased more significantly (P<0.05); compared with those in formaldehyde or benzene exposure groups, the activities of SOD in testicles of mice exposed to formaldehyde and benzene were significantly decreased(P<0.05) and the contents of MDA were significantly increased(P<0.05). (4) The frequency of comet cells in testicle cells of mice in every exposure group was significantly increased compared with that in the negative control groups(P<0.05) and the one in joint exposure groups was increased much more than that in formaldehyde or benzene exposure groups(P<0.05); in formaldehyde exposure groups, the length of comet tail in testicle cells of mice in low dose group was increased much more than that in the negative control group(P<0.05), but the one in high dose group was shortened much more(P<0.05),there was no significant difference between medium dose group and the negative control group; the length of comet tail in testicle cells of mice in benzene exposure groups was increased more significantly than that in the negative control group(P<0.05); in joint exposure groups, the length of comet tail in testicle cells of mice in low dose group was increased much more than that in formaldehyde or benzene low dose group(P<0.05), the one in medium or high dose group was increased more significantly than that in formaldehyde exposure groups(P<0.05), but shortened more significantly than that in benzene exposure groups(P<0.05). (5) The frequency of abnormal sperms of mice in every exposure group was significantly increased compared with that in the negative control groups(P<0.05); the frequency of abnormal sperms of mice in joint exposure groups was much higher than that in formaldehyde or benzene exposure groups(P<0.05).Conclusion: Formaldehyde or benzene had reproduction toxicity in male mice, they could induce pathological damages in testicles of mice; increase the frequency of abnormal sperms of mice; decrease the contents of Cu,Zn in the blood and testicles of mice; result in lipid peroxide in testicles and the DNA damage in testicle cells of mice. The reproduction toxicity in male mice of joint exposure to formaldehyde and benzene might be synergistic. The decreasing of contents of trace elements,lipid peroxide and the DNA damage might be the important mechanisms of reproduction function damage in male mice induced by Formaldehyde and benzene.