Human data are scarce . For example , a positive correlation was observed between umbilical cord blood PBDEs levels and placental expression of insulin - like growth factorbinding protein 3 ( IGFBP-3 ) , the major IGF-1 transport protein in the blood [ 175 ] . In addition , a significant positive correlation was observed between BDE-154 , BDE-209 , and IGF-1 mRNA levels in the placenta . A cord blood log of IGF-1 levels was also positively correlated with the log of BDE-196 level in breast milk and negatively with the log of BDE-85 in breast milk [ 176 ] .