Studies On The Acute Hazards Of Different Sized Nano-titanium Dioxide Particles To Mice

Objective : The safety of nano-materials has aroused people's attention with the extensive application of them. At present, the research and evaluation for the toxicity of nano-materials are still in the early stage,and there are not much literature. In addition, because of the characteristic of nanoparticles, it is possible that conventional non-toxic materials with the size reached to the nano class become toxic.TiO₂ is generally considered conventional non-toxic, but it has been reported that nano-TiO₂ is toxic. The wide application of nano-TiO₂ increased the opportunities that human expose to them, therefore it makes the research of its toxicity very critical. In this paper, oxidative damages on tissues and dysfunction of liver and kidney are studied to evaluate the acute toxic effects of nano-TiO₂, as well as provide the reference materials for the bio-safety evaluation of it.Methods:1 36 healthy mice (weight 17-22g) were divided into 3 groups randomly experiment design, and every group has 6 male and 6 female mice: control group,50nm TiO₂(5g/kg) group,120nm TiO₂(5g/kg)group.According to each of group, the suspension was given to mice by a syringe via gastrointestinal tract in a minute. One week later, the mice were sacrificed and the blood,liver,kindey,brain(cortex and hippocampus)were collected.2 The content of Ti in the organization of mice is measured by microware digestion and ICP-MS.3 The measurement of the levels of MDA,SOD and GSH-Px in serum,liver,kindey and brain(cortex and hippocampus)is used to evaluate the oxidative damage.4 The measurement of the levels of ALT,AST and ALT/AST Cr,TBIL,and BUN in serum is used to evaluate the effects of biochemical parameters in the serum.5 Observe the structure changes in liver,kidney and brain of mice by H.E staining method.Results:1 The effects of nano-TiO₂ on organ coefficient of mice There is no statistically significant difference in organ coefficient of each treatment group compared with the control group (P>0.05).2 The content of Ti in the organization of mice after poisoned by nano-TiO₂The content of Ti in 50nm group and 120nm group in liver,kidney,cerebral cortex and hippocampus is higher than control group(P<0.05);50nm group is higher than 120nm group in kindey(P<0.01).3 The MDA,SOD,GSH-Px levels in serum,liver,kidney and brain after poisoned by nano-TiO₂ 3.1 The MDA,SOD,GSH-Px levels in serum after poisoned by nano-TiO₂The level of the SOD in 50nm group is lower than control group(P<0.05);The levels of GSH-Px in 50nm group and 120nm group is lower than control group (P<0.05);MDA is higher than control group(P<0.05).3.2 The MDA,SOD,GSH-Px levels in liver after poisoned by nano-TiO₂The levels of the MDA in liver in 50nm group and 120nm group are lower than control group(P<0.05),the levels of SOD,GSH-Px is higher than control group; the levels of GSH-Px in 50nm group is lower than 120nm group(P<0.05). 3.3 The MDA,SOD,GSH-Px levels in kidney after poisoned by nano-TiO₂The levels of MDA in kidney in 50nm group and 120nm group is lower than control group(P<0.05); the levels SOD,GSH-Px are higher than control group; the levels of GSH-Px in 50nm group is lower than 120nm group(P<0.05).3.4 The MDA,SOD,GSH-Px levels in brain after poisoned by nano-TiO₂The levels of MDA in 50nm group is higher than control group(P<0.05);the levels of SOD,GSH-Px in cortex and hippocampus in 50nm group and 120nm group is lower than control group(P<0.05); the levels of SOD in cortex and hippocampus in 50nm group and GSH-Px in hippocampus are lower than control group(P<0.05). Conclusion:1 The mice poisoned by mouth of different size of nano-TiO₂,Ti can distribute in the serum,liver,kindey and the brain tissue of the mouse.2 The mice poisoned by mouth of different size of nano-TiO₂,the serum,liver,kindey and the brain tissue of the mouse are all caught acute oxidative damage.3 The mice poisoned by mouth of different size of nano-TiO₂, the liver and kindey function is damaged.4 The mice poisoned by mouth of different size of nano-TiO₂, the blood serum,liver,kindey and brain tissue of the mouse all appear pathological changes. The size of nano-TiO₂ is smaller, the pathological change is more obviously.5 There is an increasing trend of damage in mice with the TiO₂ particle size decreases, but further study is needed.