Short-Chain Polychlorinated Alkanes Exposure and Risk of Thyroid Cancer in a Population-Based Case-Control Study.

Exposure to short-chain polychlorinated alkanes (PCAs-C) can disturb thyroid homeostasis, warranting an in-depth analysis of their relationship with thyroid risk and related clinical parameters. This study recruited and obtained serum samples from 478 participants in Shandong, China, including 240 thyroid cancer patients and 238 healthy controls. PCAs-C presented as the predominant homologues in both case and control groups. PCAs-C exposure displayed an essential role in thyroid cancer risk, in which a nonlinear dose-risk relationship was observed for PCAs-C, with PCAs-C and PCAs-C exhibiting significantly reduced risks (odds ratios < 1) for thyroid cancer. Specific PCAs-C homologues were significantly associated with triglycerides, cholesterol, low-density lipoprotein cholesterol, and total lipid in the control group. Weighted quantile sum regression and Bayesian kernel machine regression revealed predominantly negative combined effects of PCAs-C exposure on thyroid cancer, thyroid hormone, and serum lipid parameters. Our results showed that exposure to the current environmental level of PCAs-C cannot heighten risks of thyroid cancer. Overall, this study first provides epidemiological evidence on the potential implications of PCAs-C exposure and thyroid cancer risk.