Abstract | BACKGROUND: Associations between perfluoroalkyl acids (PFASs) and human thyroid hormone levels remain unclear, especially during early pregnancy when small changes in maternal thyroid hormones can affect fetal brain development. OBJECTIVES: To examine associations between maternal serum PFAS levels and maternal thyroid hormone levels in the early 2nd trimester of pregnancy. METHODS: RESULTS: Median PFAS concentrations (ng/mL) in maternal sera were 1.0 (PFHxS), 0.6 (PFNA), 1.7 (PFOA) and 4.8 (PFOS). PFASs were not associated with fT4, TT4 or TSH among women with normal TPOAb. However, among the 9% of women with high TPOAb (n=14), interquartile range (IQR) increases of PFASs were associated with a 46-69% increase in maternal TSH (95% CIs ranging from 8% to 123%) (PFNA, PFOA and PFOS only), and with a 3% to 7% decrease in maternal fT4 (95% CIs ranging from -18% to 5%) (all 4 PFASs). PFNA was also associated with higher maternal TSH in the whole sample. CONCLUSIONS: PFASs were positively associated with TSH, and weakly negatively associated with fT4 in the subset of pregnant women with high TPOAb, which occurs in 6-10% of pregnancies. PFASs may exacerbate the already high TSH and low fT4 levels in these women during early pregnancy, which is a critical time of thyroid hormone-mediated fetal brain development. The clinical significance of these findings is not clear. We propose a "multiple hit hypothesis" to explain these findings; this hypothesis deserves evaluation in larger, more representative study samples.
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Authors | Glenys M Webster, Scott A Venners, Andre Mattman, Jonathan W Martin |
Journal | Environmental research
(Environ Res)
Vol. 133
Pg. 338-47
(Aug 2014)
ISSN: 1096-0953 [Electronic] Netherlands |
PMID | 25019470
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Copyright | Copyright © 2014 Elsevier Inc. All rights reserved. |
Chemical References |
- Alkanesulfonic Acids
- Caprylates
- Environmental Pollutants
- Fluorocarbons
- Sulfonic Acids
- perfluorohexanesulfonic acid
- hexadecafluoro-nonanoic acid
- Thyrotropin
- perfluorooctanoic acid
- perfluorooctane sulfonic acid
- Thyroxine
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Topics |
- Adolescent
- Adult
- Alkanesulfonic Acids
(blood)
- Caprylates
(blood)
- Cohort Studies
- Environmental Pollutants
(blood)
- Female
- Fluorocarbons
(blood)
- Humans
- Pregnancy
- Pregnancy Trimester, Second
(blood)
- Sulfonic Acids
(blood)
- Thyrotropin
(blood)
- Thyroxine
(blood)
- Young Adult
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