Amidst its shortcomings, the present study suggests the possibility of the dose-response relationship between Ni and changes in thyroid hormones/parameters of thyroid function, indicating that, especially in male population, even Ni doses higher than 0.397 and 1.36 μg/L might pose a 10% risk in the alterations of fT3 level and SPINA-GT, respectively. The gene discussed is TG; the disease is thyroid gland disorder.