Partition of Environmental Chemicals between Maternal and Fetal Blood and Tissues

Abstract

Passage of environmental chemicals across the placenta has important toxicological consequences, as well as for choosing samples for analysis and for interpreting the results. To obtain systematic data, we collected in 2000 maternal and cord blood, cord tissue, placenta, and milk in connection with births in the Faroe Islands, where exposures to marine contaminants is increased. In 15 sample sets, we measured a total of 87 environmental chemicals, almost all of which were detected both in maternal and fetal tissues. The maternal serum lipid-based concentrations of organohalogen compounds averaged 1.7 times those of cord serum, 2.8 times those of cord tissue and placenta, and 0.7 those of milk. For organohalogen compounds detectable in all matrices, a high degree of correlation between concentrations in maternal serum and the other tissues investigated was generally observed (r2 > 0.5). Greater degree of chlorination resulted in lower transfer from maternal serum into milk. Concentrations of pentachlorbenzene, γ-hexachlorocyclohexane, and several polychlorinated biphenyl congeners with low chlorination were higher in fetal samples and showed poor correlation with maternal levels. Perfluorinated compounds occurred in lower concentrations in cord serum than in maternal serum. Cadmium, lead, mercury, and selenium were all detected in fetal samples, but only mercury showed close correlations among concentrations in different matrices. Although the environmental chemicals examined pass through the placenta and are excreted into milk, partitions between maternal and fetal samples are not uniform.

Association between prenatal exposure to perfluorinated compounds and symptoms of infections at age 1–4years among 359 children in the Odense Child Cohort

“…The maternal serum concentration of PFASs before GA 16 weeks was used as proxy for prenatal exposure since PFAS has been shown to cross the placenta (Gützkow et al 2012;Needham et al 2011). Serum concentrations of PFAS are known to decrease throughout pregnancy, but PFAS measurements at different time points during pregnancy are highly correlated (Glynn et al 2012) and the compounds have long half-lives of 4-5 years (Olsen et al 2007).…”

“…The most common types are PFOS (perfluorooctane sulfonic acid), and PFOA (perfluorooctanoic acid), which are ubiquitously present in human serum, where they show an estimated elimination half-life of four years for PFOA and five years for PFOS (Calafat et al 2007;Kato et al 2011;Olsen et al 2007). They cross the placenta (Needham et al 2011) and are released through human milk (Mogensen et al 2015), thereby causing early-life exposure that may be worthy of concern. Due to changes in production, serum concentrations of some PFASs have decreased, although others have increased, including perfluorohexane sulfonic acid (PFHxS,) perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) (Glynn et al 2012).…”

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“…Further, the research reports also demonstrated that the fluoride also transferred to the infant through human breast milk 32 . That means during foetal life and early infancy, the blood brain barrier provides only partial protection against the entry of chemicals into the central nervous system 33,34 .…”

“…Fetus is not well protected against fluoride that circulates in the maternal blood. This is due to placenta does not block the passage of fluoride from maternal circulation to foetal circulation 32 and poorly developed blood brain barrier (BBB). The poorly formed BBB vasculature fails to control the entry of fluoride into the brain 6 .…”

Secondary sex ratio in relation to exposures to polychlorinated biphenyls, dichlorodiphenyl dichloroethylene and methylmercury

“…Concentrations of both ΣPCB and p,p’ -DDE were found to be higher in Cohort 3 compared to Cohorts 1 and 5 (Table 1). However, maternal lipid based serum concentrations have been shown to be 1.7 times those found in the corresponding cord serum samples [36] and the lower concentrations in Cohort 1 can, thus, be attributed to the measures being performed on cord blood rather than maternal serum. Methylmercury concentrations were found to be the highest in Cohort 1 and lowest in Cohort 5.…”