Background Perfluorinated and polyfluoroalkyl substances (PFAS), a large group of emerging pollutants, are ubiquitous in the ecological environment. Their multiple organ toxic effects on human body are reported. Understanding the exposure level of PFAS in cord serum and associated influencing factors can provide scientific evidence for studying maternal and newborn health effects and risk regulation.

Objective To explore the exposure levels of PFAS in cord serum and potential impact factors.

Methods This study was based on the maternal and infant database and the cord serum sample bank of the Sheyang Mini Birth Cohort Study (SMBCS) established in 2009. A self-designed questionnaire was used to collect information on sociodemographic characteristics, living environment, and lifestyle of mothers during pregnancy. A total of 1097 cord serum samples were measured utilizing ultra-high performance liquid chromatography-Q-Exactive Orbitrap high-resolution mass spectrometry. Multiple linear regression models were used to identify influencing factors related to PFAS exposure level in cord serum.

Results A total of 38 types of PFAS were detected in the cord serum samples, including 20 perfluorocarboxylic acids (PFCA), 14 perfluorosulfonic acids (PFSA), and 4 other types of PFAS. The detection rates of 14 PFAS compounds were above 50%. The detection rates of perfluoro-1-hexanesulfonic acid (PFHxS), perfluoro-1-octanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUdA) were in the range of 99.18%-100.00%. The median concentrations of PFOA and 6∶2 chlorinated polyfluorinated ether sulfonic acid (6∶2CI-PFESA) were higher than those of the other compounds, which were 3.76 µg·L⁻¹ and 2.61 µg·L⁻¹, respectively. The correlation coefficients among cord serum PFAS were in the wide range of 0.0911-0.8429 (P < 0.05). The associations between PFHxS and perfluoro-1-heptanesulfonic acid (PFHpS) (r=0.8429, P < 0.05), PFOS and PFHpS (r=0.7012, P < 0.05), and PFUdA and perfluorododecanoic acid (PFDoA) (r=0.7875, P < 0.05) were positive. The proportions of PFCA and PFSA in the cord serum samples were 60.1% and 38.4%, respectively. PFOA and 6∶2 Cl-PFESA were the predominant compounds in the cord serum samples, whose proportions were 37.8% and 19.3%, respectively. The concentrations of specific types of cord serum PFAS had varied associations with the following demographic variables of pregnant women: age, parity, education level, gestational age, and occupation. The multiple linear regression analysis found that the concentrations of 8 PFAS (PFHxS, PFHpS, PFNA, PFOS, PFDA, PFUdA, PFDoA, and 6∶2 CI-PFESA) in umbilical cord serum were lower in pregnant women aged 25 years and older than in those under the age of 25 years; compared to pregnant women with education levels at or below junior middle school, those with education levels at or above high school had lower concentrations of perfluoroheptanoic acid (PFHpA); the concentration of PFHpA in cord serum was negatively correlated with household annual income; multiparous women had higher concentrations of PFNA, PFUdA, and PFDoA than primiparous women; compared to mothers engaged in manual labor, the concentration of perfluoro-1-butanesulfonic acid (PFBS) in umbilical cord serum was lower in mothers engaged in mental labor, while the concentrations of PFBS and PFOA were lower and the concentrations of perfluorotridecanoic acid (PFTrDA) and 8∶2 chlorinated polyfluorinated ether sulfonic acid (8∶2CI-PFESA) were higher in mothers of other occupational types; the concentrations of umbilical cord serum PFOA, PFOS, PFUdA, and PFDoA were positively correlated with the gestational age of pregnant women, while N-methylperfluoro-1-octanesulfonamido acetic acid (N-MeFOSAA) was negatively correlated with the gestational age of pregnant women; PFTrDA was negatively correlated with the birth weight of newborns; compared with those with insufficient gestational weight gain, those with adequate gestational weight gain had lower PFDoA, while those with excess gestational weight gain had higher N-MeFOSAA.

Conclusion PFAS compounds exposure is common in the mothers and infants in the study area. PFOA and 6∶2 CI-PFESA are the two main compounds in cord serum. Cord serum PFAS are associated with several demographic characteristics of the pregnant women. Future research needs to pay more attention to PFAS alternatives and other emerging contaminants.