Genotoxicity And Mechanism Of Joint Exposuring Formaldehyde And Trichloroethylene In Mice

Objective: Both of formaldehyde and trichloroethylene have severe biotoxicityand high concentration in house, which are come from indoor-decoration and mayhave combined toxic effect on human body. Currently there are many researchs aboutthe single toxicity of formaldehyde and trichloroethylene, while few of studies areabout the joint toxicity of them, much less than the joint genotoxicity. This study isdesigned to explore the genotoxicity and the probable mechanism in mice inhalingformaldehyde and trichloroethylene, and provide the theoretical information forhereditary effects induced by indoor air pollution.Methods:108healthy and clean Kunming inbred strain mice were randomlydivided into9groups which were half male and female. The control group wasexposed at clean air, the formaldehyde exposure groups were treated with the dosageof1mg/m3,5mg/m3, the trichloroethylene treatment groups were exposed at dosageof1000mg/m3,5000mg/m3and the joint treatment groups of formaldehyde andtrichloroethylene were exposed at dosage of1+1000mg/m3,1+5000mg/m3,5+1000mg/m3,5+5000mg/m3respectively. The mice were exposed to formaldehyde andtrichloroethylene for14days,2hours per day, then killed on15th day. Thegenotoxicity of formaldehyde and trichloroethylene was tested by bone marrowpolychromatic erythrocyte micronucleus test and single cell gel electrophoresis assay.The activity of total antioxidant capacity(T-AOC), glutathione(GSH)，superoxidedismutase(SOD), and malondialdehyde(MDA) in the liver and renal of the mice weredetermined．Results:1. The genotoxic of formaldehyde and trichloroethylene on bone-marrow cellsof mice：(1) Micronucleus tests showed， When the mice were exposed toformaldehyde and trichloroethylene, the micronucleus rate was increased with theincreasing of formaldehyde and trichloroethylene, the two substances could inducedmicronucleus rate significantly (P<0.05), and there was interaction between formaldehyde and trichloroethylene in micronucleus rate (P<0.05).(2) The cometassay displayed that the formaldehyde and trichloroethylene elevated the comet rateof bone-marrow cell，tail DNA%and tail moment of comet significantly (P<0.05).The two substances have interaction in the comet rate of bone-marrow cell, tailDNA%and tail moment (P<0.05).2. Oxidative damage of liver of mice inhalation exposure for formaldehyde andtrichloroethylene: The contents of GSH and the activity of T-AOC and SOD weredeclined and the contents of MDA was elevated with the rising of the dose offormaldehyde and trichloroethylene, the two substances could induced oxidativedamage significantly (P<0.05), and there was interaction between formaldehyde andtrichloroethylene in GSH of female mice (P<0.05).3. Oxidative damage of renal of mice inhalation exposure for formaldehyde andtrichloroethylene: The contents of GSH and the activity of T-AOC and SOD weredeclined and the contents of MDA was rised with the increasing of formaldehyde andtrichloroethylene, the two substances could induced oxidative damage significantly(P<0.05), and there was interaction between formaldehyde and trichloroethylene inT-AOC of female mice (P<0.05).Conclusion: Formaldehyde and trichloroethylene had genotoxicity in mice ofsingle or joint exposure. They can give rise to DNA damage of bone-marrow cells,induce lipid peroxidation damage of liver and renal tissue. It turned out that the twochemicals may have synergistic effect on genotoxicity of mice. The lipid peroxidationdamage and DNA damage might be the important mechanisms of genetic damage ofmice caused by formaldehyde and trichloroethylene, GSH may play an important rolein the genotoxic of formaldehyde and trichloroethylene within the tissue of liver andrenal.