Toxicity and penetration of TiO(2) nanoparticles in hairless mice and porcine skin after subchronic dermal exposure.

Toxicol Lett. 2009 Jun 3; Wu J, Liu W, Xue C, Zhou S, Lan F, Bi L, Xu H, Yang X, Zeng FDThe present study investigated the penetration and potential toxicity of titanium dioxide (TiO(2)) nanoparticles nanoparticles following its dermal exposure in vitro and in vivo. In vitro, after exposure to isolated porcine skin for 24h, titanium dioxide nanoparticles of carious sizes cannot penetrate through stratum corneum. Interestingly, when studied in vivo, quite different results were obtained. After topically applied on pig ear for 30 days, TiO(2) nanomaterials (10nm, 60nm) can penetrate through horny layer, and be located in deep layer of epidermis. Furthermore, after 60 day dermal exposure in hairless mice, nano-TiO(2) particles can penetrate through the skin, enter different tissues and induce diverse pathological lesions in the major organs. Notably, P25 (21nm) TiO(2) nanomaterials shows a more wide tissue distribution, even appeared in the brain without inducing any pathological changes. Among all organs examined, the skin and liver display the most severe pathological changes that correspond to the increases in SOD and MDA levels. These results suggest that the pathological lesions are likely to be mediated through the oxidative stress induced by the deposited nanoparticles. Accordingly, the collagen content expressed as HYP content are also significantly reduced in mmouse skin samples, indicating that topical applied nano-TiO(2) in skin for a prolonged time can induce skin aging. Together, the present study indicates that nanosize TiO(2) may pose a health risk after dermal exposure over a relative long time period.