Exploring Prenatal Exposure to Halogenated Compounds and Its Relationship with Birth Outcomes Using Nontarget Analysis

Halogenated organic compounds (HOCs) are a class of contaminants showing high toxicity, low biodegradability, and high bioaccumulation potential, especially chlorinated and brominated HOCs (Cl/Br-HOCs). Knowledge gaps exist on whether novel Cl/Br-HOCs could penetrate the placental barrier and cause adverse birth outcomes. Herein, 326 cord blood samples were collected in a hospital in Jinan, Shandong Province from February 2017 to January 2022, and 44 Cl/Br-HOCs were identified with communicating confidence level above 4 based on a nontarget approach, covering veterinary drugs, pesticides, and their transformation products, pharmaceutical and personal care products, disinfection byproducts, and so on. To our knowledge, the presence of closantel, bromoxynil, 4-hydroxy-2,5,6-trichloroisophthalonitrile, 2,6-dibromo-4-nitrophenol, and related components in cord blood samples was reported for the first time. Both multiple linear regression (MLR) and Bayesian kernel machine regression (BKMR) models were applied to evaluate the relationships of newborn birth outcomes (birth weight, length, and ponderal index) with individual Cl/Br-HOC and Cl/Br-HOCs mixture exposure, respectively. A significantly negative association was observed between pentachlorophenol exposure and newborn birth length, but the significance vanished after the false discovery rate correction. The BKMR analysis showed that Cl/Br-HOCs mixture exposure was significantly associated with reduced newborn birth length, indicating higher risks of fetal growth restriction. Our findings offer an overview of Cl/Br-HOCs exposome during the early life stage and enhance the understanding of its exposure risks.

Nontarget Identification of Novel Per- and Polyfluoroalkyl Substances in Cord Blood Samples

Per- and polyfluoroalkyl substances (PFASs) can penetrate the placental barrier and reach embryos through cord blood, probably causing adverse birth outcomes. Therefore, novel PFASs identification in cord blood and their relationships with birth outcomes are essential to evaluate prenatal exposure risk of PFASs. Herein, 16 legacy and 12 novel PFASs were identified in 326 cord blood samples collected from pregnant women in Jinan, Shandong, China. The presence of perfluoropolyether carboxylic acids, hydrogen-substituted polyfluoroetherpropane sulfate, and 3:3 chlorinated polyfluoroalkyl ether alcohol in cord blood was reported for the first time. Two extensive OECD (Organization for Economic Co-operation and Development)-defined PFASs named fipronil sulfone and 2-chloro-6-(trifluoromethyl)pyridine-3-ol were also identified. Quantification results showed that the emerging and OECD-defined PFASs separately accounted for 9.4 and 9.7% of the total quantified PFASs, while the legacy PFOA, PFOS, and PFHxS were still the most abundant PFASs with median concentrations of 2.12, 0.58, and 0.37 ng/mL, respectively. Several PFASs (C₉-C₁₂ PFCAs, C₆-C₈ PFSAs, and 6:2 Cl-PFESA) showed significantly higher levels for older maternities than younger ones. PFHxS levels were positively associated with birth weight and ponderal index (p < 0.05). The results provide comprehensive information on the presence and exposure risks of several novel PFASs during the early life stage.