Rapid Precision Testing Laboratory, Cordova, TN, USA.
Photochem Photobiol. 2010 Jan-Feb;86(1):162-7. doi: 10.1111/j.1751-1097.2009.00633.x. Epub 2009 Nov 18.
The U.S. FDA recently proposed both in vivo and in vitro UVA efficacy tests for sunscreen products with the lower result used to establish the sunscreen's labeled UVA protection claim. The FDA stated their rationale for dual tests was concern that the in vivo test method overemphasizes UVA-2 (320-340 nm) photoprotection. We attribute FDA's observation to the relative lack, compared to sunlight, of UVA-1 (340-400 nm) radiation in the current JCIA UVA solar simulator specification, allowing the method to generate higher UVA protection factors than sunscreens will provide in sunlight. Our work is based upon comparisons of Air Mass 1.0 sunlight to variously filtered UVA solar simulators. Sources near the JCIA UVA-2/UVA limits (8-20%) had a goodness of fit to solar UVA of only 67-79%. We propose that instead of using ratios of UVA-2 to UVA the standard should be a goodness of fit to the UVA region of an Air Mass 1 solar reference spectrum. As the spectral distribution of solar UVA varies much less than UVB, sunlight of reasonable zenith angles of < or = 60 degrees will have similar spectral shapes and approximate risk spectrum. Goodness of fit to this spectrum will produce UVA protection values predictive to those actually achieved in sunlight of different zenith angles.
美国食品和药物管理局（FDA）最近提出了针对防晒产品的体内和体外 UVA 功效测试，使用较低的结果来确定防晒产品的标签 UVA 保护声称。FDA 表示他们进行双重测试的理由是担心体内测试方法过于强调 UVA-2（320-340nm）的光保护。我们认为 FDA 的观察结果归因于当前 JCIA UVA 太阳模拟器规格中与阳光相比相对缺乏 UVA-1（340-400nm）辐射，这使得该方法产生的 UVA 保护因子高于防晒霜在阳光下提供的保护因子。我们的工作基于对空气传播 1.0 阳光与各种过滤的 UVA 太阳模拟器的比较。接近 JCIA UVA-2/UVA 限制（8-20%）的光源与太阳 UVA 的拟合度仅为 67-79%。我们建议，标准不应使用 UVA-2 与 UVA 的比值，而应是对空气传播 1 太阳参考光谱 UVA 区域的拟合度。由于太阳 UVA 的光谱分布变化远小于 UVB，合理天顶角的阳光（<或=60 度）将具有相似的光谱形状和近似的风险光谱。对该光谱的拟合度将产生与不同天顶角阳光实际获得的 UVA 保护值相预测的 UVA 保护值。
