Polychlorinated biphenyls and thyroid hormone serum concentrations among people living in a highly polluted area: A cross-sectional population-based study

Background Polychlorinated biphenyls (PCBs) may interact with several thyroid functions. Severe environmental pollution by PCBs has been observed in Brescia, Italy, due to the presence of a factory that produced these compounds until 1984. Objectives We aimed to investigate the correlation between serum levels of total PCBs and PCB 153 and thyroid hormone serum levels in adults in a cross-sectional population-based study. Methods A total of 527 subjects were enrolled; they were face-to-face interviewed about their history of thyroid disease and provided a blood sample under fasting conditions. The serum levels of free and total triiodothyronine (FT3 and TT3), thyroxine (FT4 and TT4) and thyroid-stimulating hormone (TSH), anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-TGA), and lipid-adjusted total PCBs and PCB 153 were determined. Results There was no statistically significant difference in total PCB and PCB 153 concentrations in subjects with and without thyroid disease. Inverse, weak, statistically significant correlations were found between total PCBs and FT3 (Spearmanʹs r=−0.09) and between total PCBs and PCB 153 and TSH (Spearmanʹs r=−0.16 and −0.12, respectively). However, multiple regression analysis with FT3 and TSH serum levels as dependent variables and total PCBs and PCB 153 serum levels as predictors, including age, gender and BMI, showed a positive, rather than negative, association of PCBs and PCB 153 with FT3 and no association with TSH. Conclusions This study does not support the hypothesis that relatively high PCB environmental exposure can determine substantial alterations in thyroid function among adult people