Total oxidizable precursor assay in the determination of perfluoroalkyl acids in textiles collected from the United States
By Hongkai Zhu & Kurunthachalam Kannan
June 10, 2020
Per- and polyfluoroalkyl substances (PFASs) are used in specialty/functional textiles to impart oil, water, and stain repellency. Little is known, however, with regard to the occurrence of PFASs in textiles including infant clothing. In this study, 13 perfluoroalkyl acids (PFAAs), comprising four perfluoroalkyl sulfonic acids (PFSAs; C4–C10) and nine perfluoroalkyl carboxylic acids (PFCAs; C4–C12) were determined in 160 textile samples collected from the United States. Two extraction methods, one involving a simple solvent extraction (i.e., before oxidation) and the other with an oxidative treatment (i.e., after oxidation) of textile extracts, were used. The sum concentrations of 13 PFAAs (i.e., ∑PFAA) in textile extracts before oxidation ranged from 2 (2 (14.2 ng/g). ∑PFAA concentrations were the highest in flame retarded textiles (n = 23; mean: 13.3 μg/m2; 59.4 ng/g), followed by water repellent textiles (n = 56; 2.88 μg/m2; 12.9 ng/g) and infant clothes (n = 81; 0.521 μg/m2; 2.33 ng/g). C4–C10 PFCAs accounted for at least three-quarters of the ∑PFAA content in our textile samples. Textile extracts analyzed after oxidative treatment exhibited ∑PFAA concentrations 10-fold higher than those in extracts analyzed prior to oxidation, which suggested that PFAA precursors are used in textiles. Precursors that generated C4–C5 PFCAs, upon oxidation, were more prevalent than those that yielded PFOA. The calculated dermal exposure doses in infants of PFAAs present in clothes were at least 1–2 orders of magnitude below the reference doses proposed by the United States Environmental Protection Agency. This is the first time that the oxidative treatment was applied in the analysis of PFASs in textiles, and our results suggest the existence of PFCA precursors in textiles.