Cord blood levels of thyroid hormones and IGF-1 weakly correlate with breast milk levels of PBDEs in Taiwan

In vivo studies indicate that prenatal or neonatal exposure of rodents to polybrominated diphenyl ethers (PBDEs) disrupts thyroid hormone balance, but few studies have reported an association of PBDEs and insulin-like growth factor 1 (IGF-1). The goal was to examine whether PBDEs exposure affects the levels of thyroid hormones and IGF-1 in cord blood. Study participants were healthy pregnant women recruited from the general population in central Taiwan between 2000 and 2001 and in southern Taiwan from 2007 to 2009. One-hundred-forty-nine breast milk samples (n = 149), which were collected within one month after delivery, were analyzed using a high resolution gas chromatograph equipped with a high resolution mass spectrometer. The average and median levels of breast milk Σ14PBDEs were 5.34 and 3.38 ng/g lipid in 2000–2001 and 5.22 and 3.13 ng/g lipid in 2007–2009, respectively. In general, levels of PBDE congeners were very low in this study population and not significantly different between the years 2000–2001 and 2007–2009. Breast milk Σ14PBDEs were not significantly correlated with thyroid hormones and IGF-1 in cord blood. After examining multiple stepwise linear regression models with adjustment for maternal age, pre-pregnancy body mass index (BMI), parity, gestational age, and region (namely, central and southern Taiwan), we found that log of T4 in cord blood was significantly but slightly correlated with higher BDE-154 (B = 0.113, p = 0.017) in breast milk. The log of FT4 concentration was significantly related to a decrease in the log of BDE-99 level (B = −0.137, p = 0.043) and an increase in the log of BDE-154 level (B = 0.158, p = 0.008). Meanwhile, the log of IGF-1 level was also significantly linked to an increase in the log of BDE-196 level (B = 0.532, p = 0.028) and decrease in the log of BDE-85 level (B = −0.235, p = 0.018). Few epidemiological studies report an association between PBDEs exposure and IGF-1. Based on our findings, further in vivo and epidemiological studies are encouraged and needed to explore associations between PBDEs exposure and levels of thyroid hormones and IGF-1.