Chemical Exposures as Risk Factors for the Development of Thyroid Cancer

BACKGROUND: The incidence of thyroid cancer (TC) has risen in recent decades, prompting investigation of environmental contributors beyond traditional risk factors. SUMMARY: This narrative review examines the association between TC and chemical exposures including per- and polyfluoroalkyl substance (PFAS), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), phthalates, phenols, nitrates, and polycyclic aromatic hydrocarbons (PAHs). Several studies have shown a link between PFAS and PCB exposure and TC, particularly papillary thyroid cancer. Nitrates, even at currently accepted safe exposure levels have also been shown to have an association with TC. Findings for phthalates, PBDEs, phenols, and PAHs are inconsistent and less studied. CONCLUSION: Current evidence supports that an association exists between select chemical exposures and TC development, but study limitations prevent any direct link to causation. Further research is needed to guide clinical practice and public health policy.