8054 Temporal Trends In Thyroidal Endocrine Disruptor Exposure Among United States Reproductive-Age And Pregnant Women Over 20 Years And Differences By Socioeconomic Status

Abstract Disclosure: C. Han: None. S. Lee: None. E.N. Pearce: None. Background: Widespread exposure to endocrine disrupting chemicals (EDCs) poses a risk to public health and environmental safety. Women of reproductive age and pregnant women may be uniquely vulnerable to adverse thyroidal effects of EDCs. A better understanding of thyroidal EDCs exposure is needed to inform public health strategies. Objective: To examine temporal trends in EDC exposure and their effects on thyroid function among reproductive-age and pregnant women in the U.S. over the last two decades, with a focus on the impact of socioeconomic status. Methods: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 in 25,320 reproductive-age women and 2,525 pregnant women to assess the levels of exposure to thyroid-disrupting chemicals, including dioxins, organochlorides, polyfluoroalkyl substances (PFAS) from serum samples, and polyaromatic hydrocarbons, perchlorates, and metabolites from personal care products, phthalates, and plasticizers from urine samples. We used Kruskal-Wallis tests to analyze changes in EDC exposures over the past 20 years and multivariate linear regression models to identify factors influencing these levels. Results: We found a significant decline in exposures to 20 types of dioxins, 7 organochlorides, 6 PFAS, 5 personal care product chemicals, 6 phthalate metabolites, perchlorate, and thiocyanate, but substantial increases in exposure to 2 polyaromatic hydrocarbons among reproductive-age women. Among pregnant women, trends were similar, with declines in exposures to dioxins, organochlorides, PFAS, and phthalate metabolites; whereas exposure to 3 Polyaromatic hydrocarbons, 1 personal care product chemical, nitrates, and thiocyanates increased. Linear regression indicated a significant positive association between socioeconomic status and the levels of dioxin and PFAS in both reproductive-age and pregnant women, and a negative association between socioeconomic status and perchlorate and polyaromatic hydrocarbons in the participants. Conclusion: The past two decades have witnessed a general decline in the levels of most thyroidal EDCs in U.S. reproductive-age and pregnant women; however, some, particularly polyaromatic hydrocarbons, exposures have increased, especially among women with lower socioeconomic status. This has the potential to worsen disparities in health outcomes. These findings highlight the necessity for targeted public health interventions to reduce the impact of EDCs on thyroid health and address socioeconomic health disparities. Presentation: 6/3/2024