OR06-06 Association Between Mixed Dioxin Exposure And Thyroid Functions In U.S. Adults: A Comparison Of Three Statistical Models

Abstract Disclosure: C. Han: None. S. Lee: None. E.N. Pearce: None. Background: Previous studies of the relationship between dioxin exposure and thyroid function have usually been based on multi-chemical linear models and results have been inconsistent. However, complex nonlinear relationships and interactions between mixed dioxin exposures and thyroid function have not been studied. We applied three different statistical models to assess the joint effect of 20 dioxins on thyroid function. Methods: A total of 6 polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), 4 dioxin-like polychlorinated biphenyls (DL-PCBs) and serum TSH were measured in the serum of U.S. adults by the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2010. We fitted multivariable logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models to estimate the association of individual and mixed dioxin exposures with high TSH. Results: Among the 2818 individuals included in our analysis, 1.99% had TSH >5.6 uIU/mL. In the multivariable logistic regression established for each single dioxin, 1,2,3,7,8-pncdd, 1,2,3,4,7,8-hxcdd, 1,2,3,6,7,8-hxcdd, 1,2,3,7,8,9-hxcdd, 1,2,3,4,7,8-Hexachlorofuran, 1,2,3,6,7,8-Hexachlorofuran, 3,3',4,4',5,5'-hexachlorobiphenyl, 3,3',4,4',5-Pentachlorobiphenyl, and 2,3,7,8-Tetrachloro-p-dioxin were positively associated with high TSH, and 3,4,4',5-Tetrachlorobiphenyl was negatively associated with high TSH. In the WQS regression model, the WQS index was significantly associated (OR (95% CI): 2.03 (1.06, 3.88)) with high TSH, and 1,2,3,7,8-pncdd (weighted at 0.24) made the largest contribution. In the BKMR analysis, a significant positive association was found between mixed dioxin exposure and high TSH when all dioxins were at their 55 to 70th percentile, compared to their 50th percentile. TSH was lower when all dioxins were at their 30th to 45th percentile, compared to their 50th percentile. Conclusion: By comparing the three statistical models, we concluded that the whole-body burden of 20 dioxins was significantly positively associated with high TSH. 1,2,3,7,8-pncdd played the most important roles in hypothyroidism. Presentation: Thursday, June 15, 2023