Dunford R, Salinaro A, Cai L, Serpone N, Horikoshi S, Hidaka H, Knowland J
University of Oxford, Department of Biochemistry, UK.
FEBS Lett. 1997 Nov 24;418(1-2):87-90. doi: 10.1016/s0014-5793(97)01356-2.
Titanium dioxide (TiO2) has been noted (US Federal Register, 43FR38206, 25 August 1978) to be a safe physical sunscreen because it reflects and scatters UVB and UVA in sunlight. However, TiO2 absorbs about 70% of incident UV, and in aqueous environments this leads to the generation of hydroxyl radicals which can initiate oxidations. Using chemical methods, we show that all sunscreen TiO2 samples tested catalyse the photo-oxidation of a representative organic substrate (phenol). We also show that sunlight-illuminated TiO2 catalyses DNA damage both in vitro and in human cells. These results may be relevant to the overall effects of sunscreens.
二氧化钛（TiO₂）已被认定（美国联邦公报，43FR38206，1978年8月25日）为一种安全的物理防晒剂，因为它能反射和散射阳光中的紫外线B（UVB）和紫外线A（UVA）。然而，TiO₂会吸收约70%的入射紫外线，在水环境中，这会导致羟基自由基的产生，进而引发氧化反应。通过化学方法，我们发现所有测试的防晒TiO₂样品都会催化一种代表性有机底物（苯酚）的光氧化反应。我们还发现，经阳光照射的TiO₂在体外和人体细胞中都会催化DNA损伤。这些结果可能与防晒剂的整体效果有关。
