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BACKGROUND: Human breast milk is a primary route of exposure to perfluoroalkyl substances (PFAS) in infants. To understand the associated risks, the occurrence of PFAS in human milk and the toxicokinetics of PFAS in infants need to be addressed. OBJECTIVES: We determined levels of emerging and legacy PFAS in human milk and urine samples from Chinese breastfed infants, estimated renal clearance, and predicted infant serum PFAS levels. METHODS: In total, human milk samples were collected from 1,151 lactating mothers in 21 cities in China. In addition, 80 paired infant cord blood and urine samples were obtained from two cities. Nine emerging PFAS and 13 legacy PFAS were analyzed in the samples using ultra high-performance liquid chromatography tandem mass spectrometry. Renal clearance rates (C[L.sub.renals]) of PFAS were estimated in the paired samples. PFAS serum concentrations in infants (< 1 year of age) were predicted using a first-order pharmacokinetic model. RESULTS: All nine emerging PFAS were detected in human milk, with the detection rates of 6:2 CI-PFESA, PFMOAA, and PFO5DoDA all exceeding 70%. The level of 6:2 CI-PFESA in human milk (median concentration = 13.6 ng/L) ranked third after PFOA (336 ng/L) and PFOS (49.7 ng/L). The estimated daily intake (EDI) values of PFOA and PFOS exceeded the reference dose (RfD) of 20ng/kg BW per day recommended by the U.S. Environmental Protection Agency in 78% and 17% of breastfed infant samples, respectively. 6:2 CI-PFESA had the lowest infant C[L.sub.renal] (0.009 mL/kg BW per day), corresponding to the longest estimated half-life of 49 y. The average half-lives of PFMOAA, PFO2HxA, and PFO3OA were 0.221, 0.075, and 0.304 y, respectively. The C[L.sub.renals] of PFOA, PFNA, and PFDA were slower in infants than in adults. CONCLUSIONS: Our results demonstrate the widespread occurrence of emerging PFAS in human milk in China. The relatively high EDIs and halflives of emerging PFAS suggest potential health risks of postnatal exposure in newborns. https://doi.org/10.1289/EHP11403, Introduction Per- and polyfluoroalkyl substances (PFAS) are a broad range of synthetic chemicals widely used as water- and oil-repellents in textiles, food packaging, and leather; processing aids in the fluoropolymer [...]

A four-level rigid trunk mechanism based on 4-SPS/U, with SPS as the driving branch and U pair as the middle constrained driven branch, is innovatively proposed in this paper. Based on the innovative design of this trunk mechanism, it can improve the flexibility of the hexapod mobile robot's posture adjustment and changes in various motion modes such as walking, water propulsion, climbing and rolling. Firstly, the screw theory is adopted to calculate the degree of freedom of the trunk mechanism. Secondly, a combination of closed vector method and the characteristic structure configuration decoupling method has been applied to constructing the inverse kinematics solution, and deriving the velocity and acceleration models as well as analyzing the high posture flexibility in workspace of the trunk mechanism. Thirdly, theoretical simulation data diagram of the movement branch chain displacement, end height, speed and acceleration of the trunk mechanism are calculated through theoretical numerical examples, and the excellent motion characteristics of the 4-SPS/U-based four-level rigid trunk mechanism are analyzed. Finally, a quantitative comparison was made between the theoretical simulation data and the experimental data of the experimental prototype. The error rates of the variation curves of the displacement length, height, velocity and acceleration of the driving branch chain were 0.8%, 0.2%, 0.5% and 0.9%, which verified the correctness and reliability of the theoretical derivation. [ABSTRACT FROM AUTHOR]

Background: Epidemiological evidence remains equivocal on the associations between environmentally relevant levels of per-/polyfluoroalkyl substances (PFASs) and human semen quality. Objectives: We aimed to test whether the potential effects on semen quality could be better observed when seminal PFAS levels were used as an exposure marker compared with serum PFAS levels. Methods: Matched semen and serum samples from 664 adult men were collected from a cross-sectional population in China from 2015 to 2016. Multiple semen parameters were assessed, along with measurement of 16 target PFASs in semen and serum. Partitioning between semen and serum was evaluated by the ratio of matrix-specific PFAS concentrations. Regression model results were expressed as the difference in each semen parameter associated with the per unit increase in the ln-transformed PFAS level after adjusting for confounders. Results: Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and emerging chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) were detected at their highest concentrations in both semen and serum, with median concentrations of 0.23, 0.10, and 0.06ng/mL in semen, respectively, and a semen-to-serum ratio of 1.3:3.1. The between-matrix correlations of these PFAS concentrations were high (R = 0.70-0.83). Seminal PFOA, PFOS, and 6:2 Cl-PFESA levels were significantly associated with a lower percentage of progressive sperm and higher percentage of DNA fragmentation (false discovery rate-adjusted p-values of Conclusions: Our results suggest the potential for deleterious effects following exposure to 6:2 Cl-PFESA and other PFASs. Compared with serum PFAS levels, the much clearer association of seminal PFAS levels with semen parameters suggests its advantage in hazard assessment on semen quality, although the potential for confounding might be higher. Exposure measurements in target tissue may be critical in clarifying effects related to PFAS exposure. https://doi.org/10.1289/EHP4431, Introduction Evidence suggests that human semen quality has declined worldwide over the last several decades (Carlsen et al. 1992; Mishra et al. 2018). In addition to adverse lifestyle factors such [...]