Graduate School of the Environment, Macquarie University, North Ryde NSW 2109, Australia.
Sci Total Environ. 2012 Mar 15;420:313-8. doi: 10.1016/j.scitotenv.2011.12.046. Epub 2012 Feb 7.
In a pilot study to determine if zinc (Zn) from zinc oxide nanoparticles in sunscreen can penetrate human skin in vivo, nanoparticles (~30nm) of a stable isotope (52% (68)Zn enrichment) were incorporated into an essentially phytochemical-based formulation and applied to the backs of 3 human subjects twice daily for 5 days during the Southern Hemisphere winter. Blood and urine were collected prior to application and at regular intervals and up to 50 days. As observed in a larger outdoor trial following this pilot study but with a different formulation and with UV exposure: values of (68)Zn in blood continued to increase beyond the 5 day application phase with the highest measurement at 14 days after the first application; variable amounts of the (68)Zn tracer were observed in urine; and the amounts of extra Zn added to blood were small and indicate very low levels of absorption (minimal estimate <0.01% of the applied dose) through the skin. Reasons for differences in absorption detected in the stable isotope trials and previous investigations include: the sensitivity of the stable isotope method; the duration of the investigations; the number of applications of sunscreen formulation; in vitro methods with excised skin; lack of measurement of blood and urine; no skin flexing; and lack of UV exposure.
在一项初步研究中，研究人员试图确定防晒霜中的氧化锌纳米粒子中的锌（Zn）是否能在体内穿透人体皮肤。研究人员将（68）Zn 丰度为 52%的稳定同位素纳米颗粒 (~30nm) 掺入一种基本的植物化学配方中，并在南半球冬季的 5 天内每天两次涂抹在 3 名人类志愿者的背部。在应用前和定期以及长达 50 天的时间内收集血液和尿液。正如在这项初步研究之后进行的一项更大规模的户外试验所观察到的，但使用了不同的配方和紫外线暴露：血液中（68）Zn 的含量在应用阶段超过 5 天后继续增加，第一次应用后 14 天达到最高测量值；尿液中观察到了不同量的（68）Zn 示踪剂；添加到血液中的额外 Zn 量很小，表明通过皮肤吸收的水平非常低（最小估计值<应用剂量的 0.01%）。在稳定同位素试验和以前的研究中检测到吸收差异的原因包括：稳定同位素方法的灵敏度；研究的持续时间；防晒霜配方的应用次数；离体皮肤的体外方法；缺乏血液和尿液的测量；没有皮肤弯曲；以及缺乏紫外线暴露。
