RESUMO
Background: Titanium dioxide (TiO2), consisting of nanoparticles and sub-microparticles, were widely used as food additive and consumed by people every day, which has aroused a public safety concern. Some studies showed TiO2 can be absorbed by intestine and then distributed to different tissues after oral intake, which is supposed to affect the content of various elements in the body whereas led to tissue damage. However, knowledge gaps still exist in the impact of TiO2 on the disorder of elemental homeostasis. Thus, this study aimed to explore the oral toxicity of TiO2 by assessing its influence on elemental homeostasis and tissues injury. Method: ICR mice were fed with normal feed, TiO2 nanoparticles (NPs)-mixed feed or TiO2 submicron particles (MPs)-mixed feed (1% mass fraction TiO2 NPs or MPs were mixed in commercial pellet diet) for 1, 3, and 6 months. Particles used in this study were characterized. The distribution of Ti and other 23 elements, the correlation among elements, and pathological change in the liver, kidney, spleen and blood cells of the mice was determined. Result: Ti accumulation only appeared in blood cells of mice treated with TiO2 MPs-mixed feed for 6 months, but TiO2 cause 12 kinds of elements (boron, vanadium, iron, cobalt, copper, zinc, selenium, sodium, calcium, magnesium, silicon, phosphorus) content changed in organ tissue. The changed kinds of elements in blood cells (6 elements), liver (7 elements) or kidney (6 elements) were more than in the spleen (1 element). The TiO2 NPs induced more elements changed in blood cells and liver, and the TiO2 MPs induced more elements changed in kidney. Significantly positive correlation between Ti and other elements was found in different organs except the liver. Organ injuries caused by TiO2 NPs were severer than TiO2 MPs. Liver exhibited obvious pathological damage which became more serious with the increase of exposure time, while kidney and spleen had slight damages. Conclusion: These results indicated long-time dietary intake of TiO2 particles could induce element imbalance and organ injury. The liver displayed more serious change than other organs, especially under the treatment with TiO2 NPs. Further research on the oral toxicity of TiO2 NPs should pay more attention to the health effects of element imbalances using realistic exposure methods.