ABSTRACT:The incomplete mass-balance of organic fluorine in human serum indicates the existence of unknown per-and polyfluoroalkyl substances (PFASs) with persistent and bioaccumulative properties. Here we characterized human exposure and elimination kinetics of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in metal plating workers (n = 19), high fish consumers (n = 45), and background controls (n = 8). Cl-PFESAs were detected in >98% of the sampled individuals with serum concentrations ranging <0.019−5040 ng/mL. Statistically higher median serum levels were observed in high fish consumers (93.7 ng/mL) and metal plating workers (51.5 ng/mL) compared to the background control group (4.78 ng/mL) (Kruskal−Wallis rank sum test, p < 0.01). Cl-PFESAs could account for 0.269 to 93.3% of ∑PFASs in human serum indicating that this compound class may explain a substantial fraction of previously unidentified organic fluorine in the Chinese population. Estimated half-lives for renal clearance (median 280 years; range 7.1−4230 years) and total elimination (median 15.3 years; range 10.1−56.4 years) for the eight carbon Cl-PFESA suggest that this is the most biopersistent PFAS in humans reported to date. The apparent ubiquitous distribution and slow elimination kinetics in humans underscore the need for more research and regulatory actions on Cl-PFESAs and PFAS alternatives with similar chemical structures.

Following the global actions to phase out perfluoroctanesulfonic acid (PFOS) a large number of alternative per- and polyfluoroalkyl substances, with poorly defined hazard properties, are being used in increasing quantities. Here, we report on the first detection of the chlorinated polyfluoroalkyl ether sulfonic acid F-53B in biological samples and determine the tissue distribution and whole body bioaccumulation factors (BAFwhole body) in crucian carp (Carassius carassius). Analysis of fish samples from Xiaoqing River (XR) and Tangxun Lake (TL) demonstrated a similar level of F-53B contamination with median concentrations in blood of 41.9 and 20.9 ng/g, respectively. Tissue/blood ratios showed that distribution of F-53B primarily occurs to the kidney (TL: 0.48, XR: 0.54), gonad (TL: 0.36, XR: 0.54), liver (TL: 0.38, XR: 0.53), and heart (TL: 0.47, XR: 0.47). Median Log BAFwhole body values for F-53B (XR: 4.124, TL: 4.322) exceeded regulatory bioaccumulation criterion and were significantly higher than those of PFOS in the same data sets (XR: 3.430, TL: 3.279). On the basis of its apparent omnipresence and strong bioaccumulation propensity, it is hypothesized that F-53B could explain a significant fraction of previously unidentified organofluorine in biological samples from China, and regulatory actions for this compound are encouraged.

Short-chain perfluoroalkyl acids (PFAAs), which have less than seven fluorinated carbons, have been introduced as substitutes for eight-carbon homologue products. In this study, water, sediment, and biological samples (fish and plant) were collected from Tangxun Lake, which is located near a production base of the fluorochemical industry in Wuhan, China. Perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) were the predominant PFAAs in surface water, with average concentrations of 3660 ng/L and 4770 ng/L, respectively. However, perfluorooctane sulfonate (PFOS) was the most abundant PFAA in sediments, with an average concentration of 74.4 ng/g dw. The organic carbon normalized distribution coefficients (K OC ) indicated that shortchain PFAAs (CF 2 < 7) tended to have lower adsorption potentials than PFOS, perfluorooctanoic acid (PFOA), and longer perfluoroalkyl chain compounds. PFBS and PFBA could transport to a farther distance in the horizontal direction along the water flow and infiltrate into deeper depths in the vertical direction. However, levels of PFOS and PFOA in water dropped exponentially along the current, and their proportions were decreased gradually with the increasing depth in sediment cores. Furthermore, values of log bioconcentration factor (BCF) of the short-chain PFAAs were all relatively low (<1), indicating no bioaccumulation potentials for short-chain PFAAs in aquatic species.