The Thyroid Under Pressure: Heavy Metals, Endocrine Disruptors and Translational Insights into Carcinogenesis and Thyroid Dysfunctions

The thyroid gland is particularly vulnerable to the effects of environmental pollutants, due to its high vascularization, dependence on iodine uptake, and intrinsic oxidative environment required for hormone biosynthesis. Therefore, environmental exposure to heavy metals (HMs) and endocrine-disrupting chemicals (EDCs) has emerged as a potential contributor to thyroid dysfunction and carcinogenesis. Despite increasing interest, the clinical relevance of these exposures remains incompletely defined. Available epidemiological data suggest heterogeneous associations across EDCs and HMs classes. While evidence is more consistent for some pollutants, for other compounds it remains limited. Furthermore, while experimental studies provide strong mechanistic support for the key pathways linking environmental exposure to thyroid dysfunction and carcinogenesis, the clinical interpretation of epidemiological data is constrained by important methodological limitations. This narrative review aims to integrate current epidemiological and experimental evidence on the role of HMs and EDCs in thyroid diseases, including both non-neoplastic disorders and thyroid cancer, examining their environmental distribution, exposure pathways, and biological effects.