Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
Environ Sci Technol. 2011 Oct 15;45(20):8907-14. doi: 10.1021/es2023434. Epub 2011 Sep 16.
Perfluorooctane sulfonate (PFOS) is the most prominent perfluoroalkyl contaminant in humans and wildlife, but there is great uncertainty in exposure pathways, particularly with respect to the importance of PFOS-precursors (PreFOS). We explored the hypothesis that nonracemic proportions of chiral PFOS in serum are qualitative and semiquantitative biomarkers of human PreFOS exposure. A new chiral HPLC-MS/MS method was developed for alpha-perfluoromethyl branched PFOS (1m-PFOS, typically 2-3% of total PFOS) and applied to enantiomer fraction (EF) analysis in biological samples. In blood and tissues of rodents exposed subchronically to electrochemical PFOS, 1m-PFOS was racemic (EF = 0.485-0.511) and no evidence for enantioselective excretion was found in this model mammal. 1m-PFOS in serum of pregnant women, from Edmonton, was significantly nonracemic, with a mean EF (±standard deviation) of 0.432 ± 0.009, similar to pooled North American serum. In a highly exposed Edmonton family (mother, father, and 5 children) living in a house where ScotchGard had been applied repeatedly to carpet and upholstery, EFs ranged from 0.35 to 0.43, significantly more nonracemic than in pregnant women. Semiquantitative estimates of % serum 1m-PFOS coming from 1m-PreFOS biotransformation in both subpopulations were in reasonable agreement with model predictions of human exposure to PFOS from PreFOS. The data were overall suggestive that the measured nonracemic EFs were influenced by the relative extent of exposure to PreFOS. The possibility of using 1m-PFOS EFs for assessing the relative contribution of 1m-PreFOS (or PreFOS in general) in biological samples requires further application before being fully validated, but could be a powerful tool for probing general sources of PFOS in environments where the importance of PreFOS is unknown.
全氟辛烷磺酸 (PFOS) 是人体内和野生动物中最突出的全氟烷基污染物，但暴露途径存在很大的不确定性，特别是对于 PFOS 前体 (PreFOS) 的重要性。我们探讨了这样一个假设，即血清中手性 PFOS 的非对映比例是人体 PreFOS 暴露的定性和半定量生物标志物。我们开发了一种新的手性 HPLC-MS/MS 方法，用于分析 alpha-全氟甲基支链 PFOS（1m-PFOS，通常占 PFOS 总量的 2-3%），并应用于生物样品的对映体分数 (EF) 分析。在亚慢性暴露于电化学 PFOS 的啮齿动物的血液和组织中，1m-PFOS 是外消旋的（EF = 0.485-0.511），在这种模式哺乳动物中没有发现对映体选择性排泄的证据。来自埃德蒙顿的孕妇血清中的 1m-PFOS 明显是非对映的，平均 EF（±标准偏差）为 0.432±0.009，与北美 pooled 血清相似。在一个高度暴露于埃德蒙顿的家庭（母亲、父亲和 5 个孩子）中，他们居住在一间房屋里，这间房屋的地毯和家具曾反复使用 ScotchGard 进行处理，EF 值范围从 0.35 到 0.43，明显比孕妇更非对映。根据模型预测，在这两个亚群中，血清中 1m-PFOS 的百分比来自 1m-PreFOS 生物转化，这与从 PreFOS 中评估人类接触 PFOS 的半定量估计值大致相符。总的来说，这些数据表明，所测量的非对映 EF 值受到接触 PreFOS 相对程度的影响。在充分验证之前，使用 1m-PFOS EF 值来评估生物样品中 1m-PreFOS（或一般 PreFOS）的相对贡献的可能性需要进一步应用，但在未知 PreFOS 重要性的环境中，它可能成为探测 PFOS 一般来源的有力工具。
