Prenatal Exposure to Polychlorinated Biphenyls and Mercury Are Associated with Insulin-Like Growth Factor 1 and Thyroid-Stimulating Hormone in Cord Plasma

Abstract

Impact on maternal endocrine system during pregnancy may also affect growth and development of a fetus. Certain toxic elements and polychlorinated biphenyls (PCBs) are known to disturbe human endocrine system. In our previous study, we showed that birth weight were affected by prenatal PCBs and methylmercury exposure. In this study, we used the data from the Tohoku Study of Child Development in Japan. The objective of the study was to evaluate the effect of prenatal exposure to methylmercury, arsenic, cadmium, lead, and PCBs on insulin-like growth factor 1 (IGF-1) and thyroid related hormones (TSH, T3, freeT3, T4 and freeT4) in cord blood. Those factros are considered to be associated with fetal growth. Elements except for mercury were analyzed by an inductivity coupled plasma mass spectrometry. Mercury levels were measured using a cold vapor atomic absorption spectrometer. IGF-1 and insulin-like growth factor binding protein 1 (IGFBP1) were detemined by an enzyme-linked immunosorbent assay (ELISA). Thyroid related hormones were assessed by an electrochemiluminescence immunoassay. The data were examined by Pearson’s correlation and multiple regression analyses. The IGF-1 in cord plasma was negatively associated with PCB concentrations in cord blood, especially with tri-, tetra-, penta-, hexa- and hepta-chlorobiphenyls. Cord plasma free T4 was negatively associated with mercury concentrations in cord blood. This study indicated PCBs and mercury could affect birth weight through altering the IGF1 and T4 mechanism. Further studies are necessary to investigate the effect of decrease in IGF-1 and thyroid hormones on birth weight.