Perchlorate, Nitrate, Thiocyanate, Thyroid hormones sensitivity, National Health and Nutrition Examination Survey, Environmental sciences, GE1-350

Background: Perchlorate, nitrate, and thiocyanate are three well-known sodium iodine symporter inhibitors, however, associations of their individual and concurrent exposure with central thyroid hormones sensitivity remain unclear. Objectives: To investigate the associations of urinary perchlorate, nitrate, thiocyanate, and their co-occurrence with central thyroid hormones sensitivity among US general adults. Methods: A total of 7598 non-pregnant adults (weighted mean age 45.9 years and 52.9% men) from National Health and Nutritional Examination Survey 2007–2012 were included in this cross-sectional study. Central sensitivity to thyroid hormones was estimated with the Parametric Thyroid Feedback Quantile-based Index (PTFQI). Ordinary least-squares regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were performed to examine the associations of three anions and their co-occurrence with PTFQI. Results: The weighted mean values of urinary perchlorate, nitrate, thiocyanate, and perchlorate equivalent concentration (PEC) were 5.48 μg/L, 57.59 mg/L, 2.65 mg/L, and 539.8 μg/L, respectively. Compared with the lowest quartile, the least-square means difference (LSMD) of PTFQI was −0.0516 (LSMD ± SE: −0.0516 ± 0.0185, P