Analysis of polychlorinated biphenyls and organochlorine pesticides in archived dried blood spots and its application to track temporal trends of environmental chemicals in newborns.

Dried blood spots (DBS) collected from infants shortly after birth for the newborn screening program (NSP) in the United States are valuable resources for the assessment of exposure to environmental chemicals in newborns. The NSP was debuted as a public health program in the United States in the 1960s; and the DBS samples collected over a period of time can be used in tracking temporal trends in exposure to environmental chemicals by newborns. In this study, polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in DBS samples collected from newborns in Upstate New York from 1997 to 2011 by gas chromatography-high resolution mass spectrometry (GC-HRMS). Twelve PCBs and two OCPs were found in DBS samples at a detection rate above 50% (n=51). The mean whole blood concentration of ΣPCBs (sum of 12 congeners) over the 15-year period was 1.06 ng/mL, followed by p,p'-DDE (0.421 ng/mL) and HCB (0.065 ng/mL). The measured concentrations of PCBs and p,p'-DDE in infants'blood were comparable to those reported in cord blood, suggesting maternal/trans-placental transfer of these compounds from mothers to fetuses. The concentrations of ΣPCBs and p,p'-DDE in blood samples of infants decreased significantly between 1997 and 2001, and no significant reduction was found thereafter. This observation is consistent with the trends reported for these chemicals in other human tissues in the United States.