Relationships of Chemical Concentrations in Maternal and Cord Blood: A Review of Available Data

Abstract

The developing fetus is likely to be exposed to the same environmental chemicals as the mother during critical periods of growth and development. The degree of maternal-fetal transfer of chemical compounds will be affected by chemical and physical properties such as lipophilicity, protein binding, and active transport mechanisms that influence absorption and distribution in maternal tissues. However, these transfer processes are not fully understood for most environmental chemicals. This review summarizes reported data from more than 100 studies on the ratios of cord:maternal blood concentrations for a range of chemicals including brominated flame-retardant compounds, polychlorinated biphenyls (PCB), polychlorinated dibenzodioxins and dibenzofurans, organochlorine pesticides, perfluorinated compounds, polyaromatic hydrocarbons, metals, and tobacco smoke components. The studies for the chemical classes represented suggest that chemicals frequently detected in maternal blood will also be detectable in cord blood. For most chemical classes, cord blood concentrations were found to be similar to or lower than those in maternal blood, with reported cord:maternal ratios generally between 0.1 and 1. Exceptions were observed for selected brominated flame-retardant compounds, polyaromatic hydrocarbons, and some metals, for which reported ratios were consistently greater than 1. Careful interpretation of the data in a risk assessment context is required because measured concentrations of environmental chemicals in cord blood (and thus the fetus) do not necessarily imply adverse effects or risk. Guidelines and recommendations for future cord:maternal blood biomonitoring studies are discussed.

Tea consumption in pregnancy as a predictor of pesticide exposure and adverse birth outcomes: The MIREC Study

“…However, certain pesticides that may have been used in tea production, such as OC pesticides -including p,p′-dichlorodiphenyldichloroethylene (p,p ′-DDE) and hexachlorobenzene (HCB) -and OP pesticides, have been shown to cross the blood-placenta barrier, and thus may put the fetus at risk (Aylward et al, 2014). For example, maternal exposure to HCB has been associated with an increased risk of preterm birth (PTB).…”

Temporal trends in concentrations and total serum burdens of organochlorine compounds from birth until adolescence and the role of breastfeeding

“…One aspect to be considered in this comparison of OC concentrations at different ages is the lower lipid content in cord blood serum compared to venous serum (Aylward et al, 2014;Vizcaino et al, 2014). The average lipid content in cord blood and the 4 years serum samples of the Menorca children is 2.6 and 8.2 g/L, respectively (Carrizo et al, 2007a), and the average lipid concentrations in the 14 years serum samples is 5.2 g/L.…”

Early-life exposure to p,p′-DDT and p,p′-DDE in South African children participating in the VHEMBE study: An assessment using repeated serum measurements and pharmacokinetic modeling

“…p,p′ -DDT/E have been shown to transfer to children during pregnancy (Aylward et al, 2014) and breastfeeding (LaKind et al, 2009), resulting in exposures during critical windows of development. Multiple studies have provided evidence of the substantial impact of breastfeeding on children’s p,p′ -DDE levels.…”

“…Multiple studies have provided evidence of the substantial impact of breastfeeding on children’s p,p′ -DDE levels. Whereas neonates’ serum p,p′ -DDT/E levels are similar or slightly lower than maternal levels at birth on a lipid basis (Aylward et al, 2014), studies with longitudinal measurements have shown that children’s serum levels can increase substantially during breastfeeding (Lackmann, 2006). Studies have reported that breastfed children have higher p,p′ -DDE levels than children who had been fed formula, from as early as 6 weeks of age (Lackmann et al, 2004) to as late as 14 years (Gascon et al, 2015).…”