Mixtures of persistent organic pollutants are found in vital organs of late gestation human fetuses

Richelle D Björvang,Marie-Therese Vinnars,Nikos Papadogiannakis,Sebastian Gidlöf,Linn Salto Mamsen,Daniel Mucs,Hannu Kiviranta,Panu Rantakokko,Päivi Ruokojärvi,Christian H Lindh,Claus Yding Andersen,Pauliina Damdimopoulou

doi:10.1016/j.chemosphere.2021.131125

Abstract

Persistent organic pollutants (POPs) are industrial chemicals with long half-lives. Early life exposure to POPs has been associated with adverse effects. Fetal exposure is typically estimated based on concentrations in maternal serum or placenta and little is known on the actual fetal exposure. We measured the concentrations of nine organochlorine pesticides (OCPs), ten polychlorinated biphenyl (PCB) congeners, and polybrominated diphenyl ether (PBDE) congeners by gas chromatography – tandem mass spectrometry in maternal serum, placenta, and fetal tissues (adipose tissue, liver, heart, lung and brain) in 20 pregnancies that ended in stillbirth (gestational weeks 36–41). The data were combined with our earlier data on perfluoroalkyl substances (PFASs) in the same cohort (Mamsen et al. 2019). HCB, p,p’-DDE, PCB 138 and PCB 153 were quantified in all samples of maternal serum, placenta and fetal tissues. All 22 POPs were detected in all fetal adipose tissue samples, even in cases where they could not be detected in maternal serum or placenta. Tissue:serum ratios were significantly higher in later gestations, male fetuses, and pregnancies with normal placental function. OCPs showed the highest tissue:serum ratios and PFAS the lowest. The highest chemical burden was found in adipose tissue and lowest in the brain. Overall, all studied human fetuses were intrinsically exposed to mixtures of POPs. Tissue:serum ratios were significantly modified by gestational age, fetal sex and placental function. Importantly, more chemicals were detected in fetal tissues compared to maternal serum and placenta, implying that these proxy samples may provide a misleading picture of actual fetal exposures.

Highlights

Persistent organic pollutants (POPs) are industrial chemicals with long half-lives
LogKow is the log of the octanol–water partition coeffi cient, which is used as an approximation of lipophilicity or hydropho bicity that could potentially predict how well the chemical is transferred from maternal serum to the fetal tissues when considering only passive diffusion processes
Twenty women aged 25–40 years (BMI 20.5–34.8 kg/m2) whose pregnancies resulted in stillbirth in late gestation were included in this study based on availability of samples

Summary

Introduction

Persistent organic pollutants (POPs) are industrial chemicals with long half-lives. Early life exposure to POPs has been associated with adverse effects. Because analysis of chemicals in the developing fetus is not possible in birth cohort studies, it is common to use different matrices such as maternal serum during pregnancy, placenta, and umbilical cord blood to estimate in utero exposure to chemicals (Frederiksen et al, 2009; Leonetti et al, 2016b; Müller et al, 2019; Nanes et al, 2014; Naqvi et al, 2018; Shu et al, 2018; Tanner et al, 2020) It is unknown whether these surrogate markers provide a good and reliable estimate of fetal exposure because data on actual concentrations of POPs as well as other envi ronmental chemicals in human fetal tissues in relation to maternal serum and placenta samples is scarce. The data, which is fully disclosed, is of value to in silico modelling such as physiologically-based pharmacokinetics, and will aid in chemical health risk assessment during sensitive developmental windows

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