Study on association between human plasma polybrominated diphenyl ethers (PBDEs) and thyroid homeostasis and carcinoma

Polybrominated diphenyl ethers (PBDEs), a category of persistent organic pollutants (POPs), are ubiquitous in the environment and have been reported to have endocrine-disrupting and tumor-promoting activities. However, the evidence for the correlation between plasma PBDEs levels, thyroid homeostasis and thyroid carcinoma in humans remains limited. Herein, we analyzed eight PBDE congeners in 53 patients undergoing thyroid surgery. BDE-209 was identified as the most abundant PBDE congener in plasma (median, 11.36 ng/g lipid). BDE-100 concentration was positively associated with free triiodothyronine (FT3), indicating a potential interference with thyroid function. Point-biserial correlation analysis revealed positive associations between certain plasma PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, and BDE-154) and aggressive pathological parameters. There was no significant correlation between PBDEs and BRAF or RAS mutations in PTC patients, indicating that PBDEs may not directly promote the initiation and progression of thyroid cancer through these genetic mutations. It implies the complexity of the relationship between PBDEs exposure and thyroid cancer development. Although not statistically significant, Bayesian kernel-machine regression (BKMR) analysis of single-exposure effects model found that BDE-47 and BDE-99 were positively associated with the risk of malignant neoplasms. The present study not only contributes to the growing evidence regarding the impact of PBDEs on thyroid function but also provides new insights into the association between exposure to certain PBDE congeners and the aggressive pathological parameters of thyroid cancer. Large-scale prospective studies are still needed to support our findings.