Legacy and Emerging Environmental Organic Pollutants in Human Placenta and Blood

A laboratory procedure was developed to quantify persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in human placenta. This method was used to analyze 43 POPs (10 PBDEs including BDE-209, 32 PCBs, and DDE) in placenta collected during 2011–2012 for the “Placenta Project” of the National Children’s Study. The median Total PBDE, Total PCB, and DDE concentrations were 199 (range 54–867), 679 (range 217–2370), and 76 (range 182–4160) pg/g wwt, respectively. Among individual PBDE congeners, the concentration decreased in the rank order BDE-209>BDE-47>BDE-153>BDE-99. Among PCBs, CB-101 has the highest median concentration. The homolog abundance decreased as penta > tetra > hexa > hepta PCB. In a parallel study, 24 sets of matched feto-maternal samples collected in Chicago, Illinois during 2010–2011, were analyzed for 10 PBDEs, 32 PCBs, 31 OCPs, and 31 halogenated flame retardants (XFRs). Most abundant congeners were BDEs-47 and-209. Cord blood had the highest lipid-adjusted PBDE concentration followed by maternal blood and placenta (43.5, 35.8, and 10.5 ng/g lipid respectively). The median PCB concentrations were 74 (range 21–208), 112 (range 15–523), and 32 (8–208) ng/g lipid for maternal blood, cord blood, and placentas, respectively. Similar congener profile was observed in all matrices with CBs 153, 101, 118, 138, and 52 having higher abundances than other congeners. Among the target OCPs, hexachlorobenzine (HCB), DDE, and DDT were detected in all samples. Lipid-adjusted median maternal, placental, and cord blood DDE concentrations were 35, 8.9, and 34 ng/g lipid, respectively. The concentration ratio between maternal blood and cord blood (C/M) was calculated. Pollutants analyzed in this study displayed C/M ratios greater than one. For both PCBs and PBDEs, the C/M ratios decreased with the number of halogen substitution. Overall, the results of this study demonstrated the passing of potentially harmful chemicals into the fetal blood circulation. Presence of POPs in cord blood corroborates the prenatal exposure of human to POPs. Significant correlations existed between matrices indicating the possibility of using placenta as a noninvasive matrix to assess maternal and prenatal exposures.