Per- and polyfluoroalkyl substances (PFAS) are a complex group of man-made chemicals with high stability and mobility leading to ubiquitous environmental contamination and accumulation especially of some long-chain perfluoroalkyl acids (PFAA) in humans. While dietary intake is the main route of exposure, transdermal uptake from cosmetic products usually is considered negligible. However, PFAS are present in a part of these products, and recent epidemiological studies have provided evidence for relevant uptake via this route. The crucial question is whether PFAA in cosmetic products can cross the human skin barrier. A defined amount (110 µg) of ¹³C₄-perfluorooctanoic acid (¹³C₄-PFOA) was mixed into a sunscreen (30 g) which was applied on the whole skin of a volunteer. The plasma concentrations of ¹³C₄-PFOA were determined in serial blood samples taken over 115 days using UHPLC-MS/MS and ¹³C₂-PFOA as internal standard. After application, ¹³C₄-PFOA plasma levels increased continuously, reaching levels of 3, 56 and 118 ng/L after 6 h, 3 days and 10 days, respectively. A maximum level of 132 ng/L was measured 22 days after application, representing 9.4 % of the PFOA level resulting from the volunteer’s background exposure (1400 ng/L, equivalent to 1.4 ng/mL). In the following weeks, the levels slightly decreased with an estimated half-life of 1.8 years. The best estimate for the fraction absorbed may be 1.6 % of the dose, using a volume of distribution of 0.17 L/kg body weight. For PFOA mixed into a sunscreen, this experimental approach demonstrates a significant uptake of a PFAA via transdermal absorption in humans. In the past, some cosmetic products contained relevant PFAA levels as contaminants/impurities of PFAS added as active ingredients. Depending on these levels and the use (frequency, skin area involved), it is plausible that this route of exposure has contributed to the internal exposure to PFAA, as already suggested by epidemiological observations.

全氟和多氟烷基物质 (PFAS) 是一组复杂的人造化学品，具有高稳定性和流动性，导致普遍存在的环境污染和积累，尤其是一些长链全氟烷基酸 (PFAA) 在人体中的积累。虽然饮食摄入是主要的暴露途径，但从化妆品中经皮吸收通常被认为是微不足道的。然而，PFAS 存在于这些产品的一部分中，最近的流行病学研究为通过这种途径进行相关摄取提供了证据。关键问题是化妆品中的 PFAA 是否可以穿过人体皮肤屏障。规定量 (110 µg) 的¹³ C ₄ -全氟辛酸 ( ¹³ C ₄-PFOA) 混入防晒霜 (30 g) 中，涂抹在志愿者的整个皮肤上。^{使用 UHPLC-MS/MS 和13} C ₂ -PFOA 作为内标，在 115 天内采集的连续血样中测定¹³ C ₄ -PFOA的血浆浓度。应用后，¹³ C ₄-PFOA 血浆水平持续升高，分别在 6 小时、3 天和 10 天后达到 3、56 和 118 ng/L 的水平。施用后 22 天测得的最高水平为 132 ng/L，占志愿者背景暴露导致的 PFOA 水平的 9.4%（1400 ng/L，相当于 1.4 ng/mL）。在接下来的几周内，水平略有下降，估计半衰期为 1.8 年。使用 0.17 L/kg 体重的分布容积，对吸收分数的最佳估计可能是剂量的 1.6%。对于混合到防晒霜中的 PFOA，这种实验方法证明了 PFAA 通过人体透皮吸收显着吸收。过去，一些化妆品含有相关的 PFAA 水平，作为作为活性成分添加的 PFAS 的污染物/杂质。