Association of perfluorinated chemical exposure in utero with maternal and infant thyroid hormone levels in the Sapporo cohort of Hokkaido Study on the Environment and Children's Health.

Yusuke Iwasaki,Sachiko Itoh,Emiko Okada,Hiroyuki Nakazawa,Akiko Uno,Chihiro Miyashita,Motoyuki Yuasa,Seiko Sasaki,Sonomi Nakajima,Shizue Kato,Reiko Kishi,Toshiaki Baba

doi:10.1007/s12199-016-0534-2

Abstract

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have been widely used as industrial products, and are persistent organic pollutants due to their chemical stability. Previous studies suggested that PFOS and PFOA might disrupt thyroid hormone (TH) status. Although TH plays an important role in fetal growth during pregnancy, little attention has been paid to the relationships between maternal exposure to perfluorocarbons and TH statuses of mothers and fetuses. We investigated the effects of low levels of environmental PFOS and PFOA on thyroid function of mothers and infants. Of the eligible subjects in a prospective cohort, 392 mother-infant pairs were selected. Concentration of maternal serum PFOS and PFOA was measured in samples taken during the second and third trimesters or within 1week of delivery. Blood samples for measuring thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels were obtained from mothers at early gestational stage (median 11.1weeks), and from infants between 4 and 7days of age, respectively. Median concentrations of PFOS and PFOA were 5.2 [95% confidence interval (CI) 1.6-12.3] and 1.2 (95% CI limitation of detection-3.4) ng/mL, respectively. Maternal PFOS levels were inversely correlated with maternal serum TSH and positively associated with infant serum TSH, whereas maternal PFOA showed no significant relationship with TSH or FT4 among mothers and infants. These findings suggest that PFOS may independently affect the secretion and balances of maternal and infant TSH even at low levels of environmental exposure.

Highlights

Perfluorinated compounds (PFCs) are synthetic chemicals that have been manufactured since the 1950s
The analysis of mothers regarding the associations between maternal Perfluorooctane sulfonate (PFOS) and PFOA levels and maternal thyroid status during pregnancy were designed as the cross-sectional study, and the analysis of infants regarding the associations between maternal PFOS and PFOA levels and infants’ thyroid status at birth were designed as the prospective study
thyroid hormone (TH) are known to be crucial for fetal growth [22]

Summary

Introduction

Perfluorinated compounds (PFCs) are synthetic chemicals that have been manufactured since the 1950s. Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are the most common chemicals among PFCs, and are quite stable because of the extremely strong bond between carbon and fluorine atoms. This characteristic has made them useful as surfactants, water repellants, and a variety of other industrial products for more than half a century. Human exposure to PFCs mainly occurs orally, via the intake of contaminated food, water, and dust [1]. Their presence in human blood has been reported in several countries [2,3,4,5]. Potential adverse effects of Environ Health Prev Med (2016) 21:334–344

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