Exposure to perfluoroalkyl substances (PFAS) and associations with thyroid parameters in First Nation children and youth from Quebec

Background: Perfluoroalkyl substances (PFASs) are found in several consumer goods. Exposure to PFASs in children has been associated with alteration in thyroid hormones, which have critical roles in brain function. Objective: In 2015, 198 children and youth (3-19y) were recruited as part of the pilot project Jeunes, Environnement et Sante/Youth, Environment and Health (JES!-YEH!), realized in collaboration with four First Nation communities in Quebec. We aimed to evaluate serum concentrations of PFASs in relation to concentrations of thyroid-stimulating hormone (TSH), free thyroxine (T4) and thyroglobulin while adjusting for relevant confounders. Methods: PFASs (PFOS, PFOA, PFHxS, PFNA), 2,2',4,4'-Tetrabromodiphenyl ether (PBDE-47) thyroid parameters (TSH, free T4, and thyroglobulin) were measured in serum samples of 186 participants. Iodine, creatinine, and cotinine were measured in urine samples. Serum levels of PFASs were compared to those measured in the general Canadian population and elsewhere. Multivariate regression analyses were performed to determine associations between PFASs and TSH, free T4 and thyroglobulin. Results: PFOS, PFOA and PFHxS serum concentrations were low. However, PFNA concentrations among participants aged 12 to 19 years old from Anishinabe communities were three times higher than those measured in the Canadian Health Measures Survey (2009-2011) for the same age group (Geometric Means: 3.01 mu g/L and 0.71 mu g/L, respectively) and were particularly higher in the Anishinabe participants aged 6 to 11 years old (GM: 9.44 mu g/L). Few participants had levels of TSH, free T4, and thyroglobulin outside age-specific paediatric ranges. When adjusted for relevant covariates and other contaminants, PFNA serum concentrations were positively associated with free T4 levels (Adjusted beta = 0.36; p = 0.0014), but not with TSH and thyroglobulin levels. No association was observed between the other PFAS and thyroid hormones parameters. Conclusion: This pilot project reveals among the highest exposure to PFNA in children reported until today, and suggests effects of PFNA as an endocrine disruptor, highlighting the importance of investigating the sources and effects of disproportionate exposure to emerging contaminants in some indigenous communities and ban all PFAS at the international scale.