Associations between Exposure to Persistent Organic Pollutants and Thyroid Function in a Case-Control Study of East China

Animal studies have indicated that persistent organic pollutants (POPs) affect thyroid hormone homeostasis, while epidemiological studies involving human have not shown consistent results. In this study, we investigated the associations between POP exposure and thyroid function among adult population of East China. One hundred eighty-six participants diagnosed with thyroid disease and 186 participants without thyroid disease from Shandong, China were enrolled in the case-control study during 2016 to 2017. We found that POP exposure was significantly and positively associated with the risk of thyroid disease. The association of thyroid disease with a sum of 17 POPs followed a nonmonotonic dose response, with an adjusted odds ratio of 2.09 (95% confidence intervals: 1.13-3.87, p = 0.019) for the second quartile. Among 186 participants in the control group, concentrations of POPs showed negative associations with triiodothyronine (T3), free T3 (FT3), thyroxine (T4), and free T4 (FT4) in males and positive associations with T4 and FT4 in females. Taken together, these findings suggest that POP exposure can disrupt thyroid hormone homeostasis and increase the risk of thyroid disease.