Purpose: To evaluate human exposure to PFASs, this study quantified six perfluorocarboxylic acids (PFCAs) and two perfluorosulfonic acids (PFSAs) in fourteen majorly consumed foods (total 140 samples) in Taiwan using UPLC-MS/MS with isotope-dilution techniques.
Methods: One-gram homogenized wet samples were digested with 10 ml of 0.5 N potassium hydroxide (KOH) in methanol, and 5-ml supernatant of the samples after centrifugation were diluted with 500-ml Milli-Q water, adjusted to pH 3.5, and were extracted with Atlantic HLB disk by automated solid-phase extraction. Analytes were eluted with 20-ml methanol containing 0.1% ammonium hydroxide (v/v); the eluent were concentrated to 1 ml by a SpeedVac and were analyzed by ultra-high performance liquid chromatography/tandem mass spectrometry at negative electrospray ionization.
Results: The long-chained PFCAs with 10 - 12 carbons were detected in all of the samples with the geometric means ranged from 0.04 to 12.3 ng/g, which were higher than previous reports. Perfluorooctane sulfonate (PFOS) was not detected as frequently as demonstrated in other studies and the measured concentrations ranged from 0.11 ng/g (clam) to 9.91 ng/g (pork liver) in average. Rice and pork liver were rarely studied but some considerable concentrations, such as up to 283 ng/g of perfluorooctanoic acid (PFOA) in liver, were observed in this study.
Significance: Although the daily intake of PFOA (85.1 ng/kg b.w./day) and PFOS (0.46 ng/kg b.w./day) did not exceed the tolerable daily intake suggested by the European Union, Germany, and the U.K., people in Taiwan exposed to more perfluorohexanoic acid, PFOA, perfluorodecanoic acid, and perfluoroundecanoic acid (11.2, 85.1, 44.2, and 4.45 ng/kg b.w./day, respectively) than in western countries, demonstrating that the distribution of PFASs and the dietary habits are crucial to the exposure.