Placental Transfer of Perfluoroalkyl Substances and Associations with Thyroid Hormones: Beijing Prenatal Exposure Study

Abstract

Perfluoroalkyl substances (PFASs) have been detected in wildlife and human samples worldwide. Toxicology research showed that PFASs could interfere with thyroid hormone homeostasis. In this study, eight PFASs, fifteen PFAS precursors and five thyroid hormones were analyzed in 157 paired maternal and cord serum samples collected in Beijing around delivery. Seven PFASs and two precursors were detected in both maternal and cord sera with significant maternal-fetal correlations (r = 0.336 to 0.806, all P < 0.001). The median ratios of major PFASs concentrations in fetal versus maternal serum were from 0.25:1 (perfluorodecanoic acid, PFDA) to 0.65:1 (perfluorooctanoic acid, PFOA). Spearman partial correlation test showed that maternal thyroid stimulating hormone (TSH) was negatively correlated with most maternal PFASs (r = −0.261 to −0.170, all P < 0.05). Maternal triiodothyronin (T3) and free T3 (FT3) showed negative correlations with most fetal PFASs (r = −0.229 to −0.165 for T3; r = −0.293 to −0.169 for FT3, all P < 0.05). Our results suggest prenatal exposure of fetus to PFASs and potential associations between PFASs and thyroid hormone homeostasis in humans.

Perfluoroalkyl substances exposure and thyroid hormones in humans: epidemiological observations and implications

“…However, in the same population of China, many long chain PFASs measured in maternal serum showed negative associations with maternal TSH, not supporting hypothyroidism effects of PFASs exposure39). Some studies also reported similar inconsistent observations224041).…”

“…In Chinese mother and child pairs recruited in Beijing (n=157), maternal perfluorododecanoic acid also showed negative associations with free and total thyroid hormones. In addition, the levels of long chain PFASs, e.g., PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFHxS, or PFOS in cord serum, showed negative associations with maternal tT3 levels39).…”

Effects of perfluorooctanoic acid exposure during pregnancy on the reproduction and development of male offspring mice

“…Although manufacture of PFOA has been ceased in 2015, PFOA can remain in the environment such as the atmosphere, soil, rivers and silt, with a serum harm‐life of 16–22 days in mice (Lou et al., ) and 2–4 years in humans (Seals, Bartell, & Steenland, ). The detection of PFOA in human and laboratory animal umbilical cord blood (Kato et al., ; Llorca et al., ; Yang et al., ) and breastmilk (Fenton et al., ; Fromme et al., ; Kang et al., ; Llorca et al., ; So et al., ) has raised concerns over the exposure of offspring during development.…”

Per‐ and polyfluoroalkyl substances in Northern California cats: Temporal comparison and a possible link to cat hyperthyroidism

“…Epidemiologic and toxicologic studies have reported the potential of PFASs, particularly PFOAs and PFOSs, to act as endocrine-disruptors, impairing thyroid function through pathways including competing for thyroid hormone binding proteins, such as transthyretin (Weiss et al 2009;Ballesteros et al 2017). However, studies on human thyroid hormones and PFAS exposures have not been conclusive (Bloom et al 2010;Melzer et al 2010;Ji et al 2012;Webster et al 2014;Shrestha et al 2015;Yang et al 2016). Modest associations between PFOAs and thyroid hormones (negative for T4 and positive for T3) were reported in a study on 506 PFOA production workers (Olsen and Zobel 2007).…”