Fluorinated compounds, including a novel oxidizable fraction in blood of Norwegian women and their predictors - the Norwegian Women and Cancer Study

Abstract

Per and polyfluoroalkyl substances (PFASs) are persistent organic pollutants (POPs) and more than 4000 different PFASs can be found today. They are used in several industrial applications (greaseproof paper, firefighting foam, stain repellents) because of their hydrophobic and lipophobic characteristics. PFOS (a perfluoroalkyl sulfonic acid (PFSA)) and PFOA (a perfluoroalkyl carboxylic acid (PFCA)) are the two compounds most detected in the environment. The diet is the most dominant environmental exposure route and PFASs are found in various food products, like fish, meat, eggs, and vegetables. This study was conducted to assess the concentrations of conventional PFASs compounds and their predictors in plasma of 316 middle-aged women of the Norwegian women and Cancer Study (NOWAC) and in a subgroup the concentrations of novel oxidizable compounds using the total oxidizable precursor assay (TOPA). Birthyear was found to be the strongest predictor, where older women had elevated levels of most of the investigated PFASs. PFOS (median 19.9 ng/mL), PFOA (2.9 ng/mL), PFPeA (0,9 ng/mL), PFUnDA (0,4 ng/mL) and PFHxS (1 ng/mL) were detected in more than 99 % of the plasma samples. The PLS regression plots indicated a positive association with a cluster of marine foods and almost all the investigated PFASs, except for PFPeA which was pastries. The TOPA method on the subgroup indicated on average a twice as high sum of PFCAs after oxidation and indicates that we are exposed to unknown oxidizable precursor compounds. The fraction was poorly correlated to the traditional PFASs and indicates that the sources are different.