A Critical Review on Transplacental Transfer of Per- and Polyfluoroalkyl Substances: Prenatal Exposure Levels, Characteristics, and Mechanisms

Abstract

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) has aroused public concerns as it can pose multiple health threats to pregnant women and cause adverse birth outcomes for fetuses. In previous studies, the prenatal exposure levels and transplacental transfer efficiencies (TTE) of PFASs have been reported and discussed. Specifically, the binding affinities between PFASs and some transporters were determined, demonstrating that the TTE values of PFASs are highly dependent on their binding behaviors. To summarize primary findings of previous studies and propose potential guidance for future research, this article provides a systematic overview on levels and characteristics of prenatal exposure to PFASs worldwide, summarizes relationships between TTE values and structures of PFASs, and discusses possible transplacental transfer mechanisms, especially for the combination between PFASs and transporters. Given the critical roles of transporters in the transplacental transfer of PFASs, we conducted molecular docking to further clarify the binding behaviors between PFASs and the selected transporters. We proposed that the machine learning can be a superior method to predict and reveal behaviors and mechanisms of the transplacental transfer of PFASs. In total, this is the first review providing a comprehensive overview on the prenatal exposure levels and transplacental transfer mechanisms of PFASs.

A Critical Review and Meta-Analysis of Impacts of Per- and Polyfluorinated Substances on the Brain and Behavior

“…The placenta serves as an important biological barrier with the ability to allocate nutrients, hormones, and growth factors to the fetus while also limiting fetal exposure to some toxic substances. PFAS have been detected in serum from maternal, cord, and newborn blood demonstrating that these chemicals are capable of passing through the placental barrier, with estimates of the efficiency of placental transfer ranging from 30—79% ( Gützkow et al, 2012 ; Ma et al, 2021 ). In addition, breast milk has been shown to account for 83—99% of PFAS total daily intake for infants ( Haug et al, 2009 ; Sundström et al, 2011 ; Gützkow et al, 2012 ; Winkens et al, 2017 ; Liu et al, 2020 ; Ma et al, 2021 ).…”

“…PFAS have been detected in serum from maternal, cord, and newborn blood demonstrating that these chemicals are capable of passing through the placental barrier, with estimates of the efficiency of placental transfer ranging from 30—79% ( Gützkow et al, 2012 ; Ma et al, 2021 ). In addition, breast milk has been shown to account for 83—99% of PFAS total daily intake for infants ( Haug et al, 2009 ; Sundström et al, 2011 ; Gützkow et al, 2012 ; Winkens et al, 2017 ; Liu et al, 2020 ; Ma et al, 2021 ). Beyond direct maternal transfer, infants and toddlers may experience higher exposures than adults for several additional reasons.…”

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

“…Fetuses are highly sensitive to xenobiotics, so early life exposure could have strong and persistent impacts on normal development. Numerous studies have verified that PFASs can penetrate the placental barrier and reach the embryos through umbilical cord blood, relating to adverse health effects and birth outcomes of fetuses, such as low birth weight, decrease in immune function, and endocrine disorder. − However, mass balance analysis results showed that an average of 9% of extractable organofluorine (EOF) was unidentified in cord serum, indicating the presence of unknown PFASs in exposed fetuses . Consequently, the novel PFASs identification in cord blood and their relationship with birth outcomes are essential to evaluate prenatal exposure risk of PFASs.…”

Nano-TiO2retarded fetal development by inhibiting transplacental transfer of thyroid hormones in rats

“…A developing fetus is especially vulnerable to toxicants, raising significant concerns over children's health. [1][2][3] The most common developmental abnormalities are attributed to maternal exposure to toxins. 4 Recognizing the increasing applications of nanoparticles (NPs) in commercial products, evidence accumulates that certain NPs can overcome the placental barrier and pose adverse effects on fetal development.…”