Partition of Environmental Chemicals between Maternal and Fetal Blood and Tissues

TLDR

The transfer of environmental chemicals across the placenta has significant toxicological implications and influences sample selection and result interpretation. The study aimed to systematically collect maternal and cord blood, cord tissue, placenta, and milk samples from Faroe Islands births in 2000 to assess marine contaminant exposure. Fifteen sample sets were analyzed for 87 environmental chemicals, most of which were detected in both maternal and fetal tissues. Maternal serum organohalogen concentrations were on average 1.7‑fold higher than cord serum, 2.8‑fold higher than cord tissue and placenta, and 0.7‑fold higher than milk, with strong correlations (r² > 0.5) across matrices, but transfer varied by compound—greater chlorination reduced milk transfer, low‑chlorinated congeners were higher in fetal samples with poor correlation, perfluorinated compounds were lower in cord serum, and only mercury showed consistent cross‑matrix correlation—demonstrating non‑uniform partitioning.

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.