title: Persistent organic pollutants and transthyretin-bound thyroxin in plasma of Inuit women of childbearing age.
abstract: The Inuit population of Nunavik (Northern Quebec, Canada) is highly exposed to persistent organic pollutants (POPs) through their traditional diet. Some POPs, i.e., hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs), pentachlorophenol (PCP), and perfluorooctane sulfonate (PFOS), compete with thyroxin (T4) for binding sites on transthyretin (TTR), a T4 transport protein found in plasma and cerebrospinal fluid. We tested the hypothesis that these TTR-binding compounds decrease circulating concentrations of T4 bound to TTR (T4-TTR) in Inuit women of reproductive age. We measured the concentration of T4-TTR in plasma samples obtained from 120 Inuit women (18-39 years old) by combining native-polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. Total T4, TTR, and thyroxin-binding globulin (TBG) concentrations were also determined, while POPs levels had been previously measured. The mean T4-TTR concentration was 8.4 nmol/L (SD = 2.4) with values ranging from 2.9 to 14.4 nmol/L. Linear regression analysis revealed that TTR, TBG, and total T4 concentrations were significant predictors (p < 0.002) of T4-TTR levels (total adjusted R-squared = 0.26, p < 0.0001) but not levels of OH-PCBs, chlorophenols, or PFOS. Our results suggest that circulating levels of these TTR-binding compounds in Inuit women of childbearing age are not high enough to affect TTR-mediated thyroid hormone transport. The possibility of increased delivery of these compounds to the developing brain requires further investigation.
authors.affiliation: Axe Santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, Québec, QC, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Audet-Delage
authors.forename: N
authors.initials: N
authors.lastname: Ouellet
authors.forename: R
authors.initials: R
authors.lastname: Dallaire
authors.forename: E
authors.initials: E
authors.lastname: Dewailly
authors.forename: P
authors.initials: P
authors.lastname: Ayotte
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D006801:Humans; D004930:Inuit; D016014:Linear Models; D009930:Organic Chemicals / Q000097:blood*; D011228:Prealbumin / Q000378:metabolism*; D011792:Quebec; D012098:Reproduction; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D009930:Organic Chemicals; D011228:Prealbumin; D014284:Triiodothyronine; D013974:Thyroxine