Division of Genetics and Molecular Medicine, St John's Institute of Dermatology, King's College London School of Medicine, Guy's Hospital, London, UK.
J Invest Dermatol. 2010 Oct;130(10):2457-62. doi: 10.1038/jid.2010.144. Epub 2010 Jun 10.
We lack comparative data on sunscreens with comparable sun protection factors (SPFs), but with different levels of UVA protection, especially against cumulative erythema from repeated suberythemal exposure. Thus, we compared the protection from cumulative sunburn with two sunscreens labeled SPF 6, but with different UVR-absorbing properties, one that absorbs the UVB waveband and the other that absorbs UVB+UVA wavebands. We simulated sunlight typical of temperate latitudes to expose skin daily to suberythemal doses for 13 consecutive days. The study population consisted of eight fair-skinned sun-sensitive healthy young adults. Erythema was assessed by eye and objectively, and the SPF of each sunscreen was modeled with changes in solar UVR with time of day and latitude. The broad-spectrum sunscreen gave much better protection against cumulative erythema than the UVB sunscreen. The explanation for this is that UVA makes a greater contribution toward sunburn at temperate latitudes than under the laboratory conditions in which SPF is tested and assigned. The data support the current trend toward broad-spectrum sunscreen protection. They also show that labeled SPF is much more reliable with broad-spectrum sunscreens because SPF with primarily UVB sunscreens is dependent on time of day and latitude.
我们缺乏具有可比防晒因子 (SPF) 的防晒霜的比较数据，但具有不同水平的 UVA 保护，特别是针对重复亚红斑暴露的累积红斑。因此，我们比较了两种标签为 SPF 6 的防晒霜的累积晒伤保护，它们具有不同的 UVR 吸收特性，一种吸收 UVB 波段，另一种吸收 UVB+UVA 波段。我们模拟了温带地区典型的阳光，每天让皮肤暴露在亚红斑剂量下，持续 13 天。研究人群由 8 名皮肤白皙、敏感的健康年轻人组成。通过眼睛和客观评估红斑，并且用每天和纬度的太阳紫外线辐射变化来模拟每种防晒霜的 SPF。广谱防晒霜比 UVB 防晒霜能更好地防止累积红斑。这一结果的解释是，在温带地区，UVA 对晒伤的贡献比在测试和分配 SPF 的实验室条件下更大。这些数据支持了广谱防晒霜保护的当前趋势。它们还表明，具有广谱防晒霜的标签 SPF 更可靠，因为主要用于 UVB 防晒霜的 SPF 取决于时间和纬度。
