Association of per- and polyfluoroalkyl substances with thyroid homeostasis during pregnancy in the SELMA study.

To investigate the association of exposure to per- and polyfluoroalkyl substances (PFAS) during early pregnancy with markers of the maternal thyroid system. Serum concentrations of seven PFAS as well as thyroid stimulating hormone (TSH), free and total thyroxine (FT4 and TT4), free and total triiodothyronine (FT3 and TT3) were measured in pregnant women in early pregnancy in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study. Outcomes were concentrations of TSH and thyroid hormones, FT4/FT3 or TT4/TT3 ratios, TSH/FT4 ratio as a marker of the negative feedback loop, TT4/FT4 or TT3/FT3 ratios as markers of the binding of thyroid hormones to binding proteins. The study population comprised 2,008 women with median (95% range) gestational age of 10 (6-14) weeks. There was no association between PFAS and TSH. Higher PFNA, PFDA, PFHpA and PFOA levels were associated with a higher FT4 (largest effect estimate for PFDA: β [95% CI]: 0.27 [0.10 to 0.45], P = 0.002). Higher PFUnDA levels, but no other PFAS, were associated with a lower FT3 (β [95% CI]: -0.05 [-0.09 to -0.01], P = 0.005). Higher PFUnDA levels were associated with lower TT4 (β [95% CI]: -1.58 [-3.07 to -0.09]) and there was an inverted U-shaped association of PFOS with TT4 (P = 0.03). Higher PFDA, PFUnDA, PFHpA levels were associated with a lower TT3. Overall, higher PFAS concentrations were associated with a higher FT4/FT3 ratio and a higher TT4/TT3 ratio. There was no association of PFAS with the TSH/FT4 ratio. Higher concentrations of several PFAS were associated with lower TT4/FT4 and TT3/FT3 ratios. These findings translate results from experimental studies suggesting that exposure to PFAS may interfere with the thyroid system during pregnancy. Further experimental studies should take into account human evidence to better understand the potential underlying mechanisms of thyroid disruption by PFAS exposure.

Derakhshan A ，Kortenkamp A ，Shu H ，Broeren MAC ，Lindh CH ，Peeters RP ，Bornehag CG ，Demeneix B ，Korevaar TIM ... -  《-》

Reference Ranges and Determinants of Thyroid Function During Early Pregnancy: The SELMA Study.

Derakhshan A ，Shu H ，Broeren MAC ，de Poortere RA ，Wikström S ，Peeters RP ，Demeneix B ，Bornehag CG ，Korevaar TIM ... -  《-》

Association of urinary bisphenols and triclosan with thyroid function during early pregnancy.

Bisphenols and triclosan are considered as potential thyroid disruptors. While mild alterations in maternal thyroid function can result in adverse pregnancy and child developmental outcomes, there is still uncertainty whether bisphenols or triclosan can interfere with thyroid function during pregnancy. We aimed to investigate the association of urinary bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF) and triclosan with early pregnancy thyroid function. This study was embedded in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (SELMA), a population-based prospective pregnancy cohort. In total, 1996 participants were included in the current study. Maternal urinary concentrations of three bisphenols and triclosan, collected at median (95% range) 10 (6-14) weeks of pregnancy as well as serum concentrations of thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3) were measured. Higher BPA levels were associated with lower TT4 concentrations (non-monotonic, P = 0.03), a lower FT4/FT3 ratio (β [SE] -0.02 [0.01], P = 0.03) and a lower TT4/TT3 ratio (β [SE] -0.73 [0.27], P = 0.008). Higher BPF levels were associated with a higher FT3 (β [SE] 0.01 [0.007], P = 0.04). There were no associations between other bisphenols or triclosan and absolute TSH, (F)T4 or (F)T3 concentrations. The association of BPA with thyroid function differed with gestational age. The negative association of BPA with FT4/FT3 and TT4/TT3 ratios was only apparent in early but not late gestation (P for interaction: 0.003, 0.008, respectively). These human data during pregnancy substantiate experimental findings suggesting that BPA could potentially affect thyroid function and deiodinase activities in early gestation.

Derakhshan A ，Shu H ，Peeters RP ，Kortenkamp A ，Lindh CH ，Demeneix B ，Bornehag CG ，Korevaar TIM ... -  《-》

The Association of Maternal Iodine Status in Early Pregnancy with Thyroid Function in the Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy Study.

Levie D ，Derakhshan A ，Shu H ，Broeren MAC ，de Poortere RA ，Peeters RP ，Bornehag CG ，Demeneix B ，Korevaar TIM ... -  《-》

Higher free thyroxine associated with PFAS exposure in first trimester. The Odense Child Cohort.

Perfluoroalkyl substances (PFAS) are endocrine disrupting chemicals with elimination half-lives ranging from four to eight years. Experimental studies found PFAS able to interfere with thyroid hormone-binding proteins. During the first 20 weeks of gestation (GW), the fetus is reliant on placental transfer of maternal thyroid hormones, mainly free thyroxine (FT4). However, previous studies investigating associations between exposure to PFAS and thyroid hormone status mainly focused on blood samples from late pregnancy or umbilical cord with mixed findings. To investigate associations between serum-PFAS concentrations and thyroid hormone status in early pregnancy as reflected by FT4 and thyroid-stimulating hormone (TSH). In the Odense Child Cohort, a single-center study, we measured maternal pregnancy serum concentrations of five PFAS: perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA); and FT4 and TSH in 1048 pregnant women at median GW 12 (25th, 75th percentile: 10, 15). Multivariate linear regression models were performed to estimate associations between PFAS exposure and thyroid hormone status. A doubling in PFOS, PFOA, and PFNA concentrations was associated with an increment in FT4 concentration by 1.85% (95% CI: 0.66%, 3.05%), 1.29% (95% CI: 0.21%, 2.39%), and 1.70% (95% CI: 0.48%, 2.94%), respectively, in adjusted analyses. A statistically significant dose-response relationship was observed across exposure quartiles for PFOS, PFOA, and PFNA in the association with FT4. No association was found between concentrations of PFAS and TSH in adjusted analyses. Exposure to PFOS, PFOA, and PFNA was associated with higher FT4 concentrations in women during early pregnancy. The potential clinical implications of these findings remain to be clarified.

Jensen RC ，Glintborg D ，Timmermann CAG ，Nielsen F ，Boye H ，Madsen JB ，Bilenberg N ，Grandjean P ，Jensen TK ，Andersen MS ... -  《-》