TSHR and thyroid tumor: The purpose of the present research was to investigate some OCPs (e.g., α-HCH, β-HCH, γ-HCH, 2,4 DDE, 4,4 DDE, 2,4DDT and 4,4DDT) impacts on the promoter methylation of TSHR, ATM, and P16 tumor suppressor genes and histone lysine acetylation (H3K18, H3K9, and H4K16) and lysine methylation (H4K20) in thyroid tumor patients.