Lu P J, Ho I C, Lee T C
Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
Mutat Res. 1998 May 11;414(1-3):15-20. doi: 10.1016/s1383-5718(98)00034-5.
Titanium dioxide (TiO2) has color properties of extreme whiteness and brightness, is relatively inexpensive, and is extensively used as a white pigment in a variety of materials. TiO2, an effective blocker of ultraviolet light, is frequently added to sunscreens and cosmetic creams. However, the genotoxicity of TiO2 remains to be controversial. In this report, we have demonstrated that TiO2 can be transported into Chinese hamster ovary-K1 (CHO-K1) cells. The effects of TiO2 on induction of sister chromatid exchanges (SCE) and micronuclei (MN) were then studied in these cells. The SCE frequency in CHO-K1 cells treated with TiO2 at a nonlethal dose range (0 to 5 microM) for 24 h was significantly and dose-dependently increased. By the conventional MN assay, TiO2 at the dose ranged from 0 to 20 microM slightly increased the MN frequency in CHO-K1 cells. However, in the cytokinesis-block MN assay, the number of MN per 1000 binucleated cells was significantly and dose-dependently enhanced in CHO-K1 cells treated TiO2 at the same dose range for 24 h. These results suggest that TiO2 is a potential genotoxic agent.
二氧化钛（TiO₂）具有极高的白度和亮度等颜色特性，价格相对低廉，被广泛用作各种材料中的白色颜料。TiO₂是一种有效的紫外线阻滞剂，常被添加到防晒霜和美容霜中。然而，TiO₂的遗传毒性仍存在争议。在本报告中，我们证明了TiO₂可以转运到中国仓鼠卵巢-K1（CHO-K1）细胞中。然后在这些细胞中研究了TiO₂对姐妹染色单体交换（SCE）和微核（MN）诱导的影响。在非致死剂量范围（0至5微摩尔）处理24小时的CHO-K1细胞中，TiO₂处理后的SCE频率显著且呈剂量依赖性增加。通过传统的微核试验，剂量范围为0至20微摩尔的TiO₂使CHO-K1细胞中的微核频率略有增加。然而，在胞质分裂阻滞微核试验中，在相同剂量范围处理24小时的CHO-K1细胞中，每1000个双核细胞中的微核数量显著且呈剂量依赖性增加。这些结果表明TiO₂是一种潜在的遗传毒性剂。
