Polychlorinated naphthalenes in the serum of individuals with thyroid dysfunction and their potential mechanisms of impact on disease progression

Polychlorinated naphthalenes (PCNs) comprise 75 congeners, with varying concentrations and major congeners across different populations. Recent studies have found a relationship between PCNs and thyroid hormone levels, suggesting they may interfere with thyroid function. Investigating the concentrations of PCNs in individuals with thyroid dysfunction helps identify the predominant congeners and enables targeted analysis of their interference with thyroid function. In this study, serum concentrations of PCNs from 55 adults with thyroid dysfunction were measured. PCN-13, -15, −17/25/26, −20, −23, and −24/14 detected at over 70 %, and PCN-23 and -24/14 being the major congeners. No significant difference in PCN concentrations was found between males and females, but the concentrations of PCN-23 and -24/14 increased with age. Logistic regression and QGC models revealed a significant association between PCN-23 and thyroid dysfunction, while mediation analysis indicated PCN-23 affects physiological processes involving the BRAF 600E gene, which influences normal thyroid function. Molecular docking results showed that all six PCNs impacted thyroid hormone metabolism and receptor binding, with PCN-23 binding more effectively to TBG and disrupting thyroid hormone transport compared to PCN-24/14. Future studies should focus on the concentrations of trichlorinated PCNs, particularly PCN-23, in the human body and their relationship with thyroid function.