Ambient Black Carbon Particles Travel From Mother Into the Fetal Circulation and Organs During Gestation

Background and Aim: Prenatal exposure to particulate air pollution has been linked to multiple adverse birth outcomes causing burden of disease later in life. To date, evidence is lacking whether ambient particulates can both reach and cross the human placenta to exert direct effects on fetal organ systems during gestation. Methods: We used white light generation under femtosecond pulsed illumination to detect black carbon particles in samples collected at the maternal-fetal interface. Maternal-perinatal and fetal samples were collected within the framework of two independent studies, including the mother-newborn ENVIRONAGE (ENVIRonmental influence ON AGEing in early life) Belgian birth cohort and the SAFeR (Scottish Advanced Fetal Research) Scottish cohort of electively terminated normally progressing pregnancies. Appropriate validation experiments were performed to confirm the carbonaceous nature of the identified particles. Results: Here, we provide evidence of (i) the presence of black carbon particles in cord blood, confirming their ability to cross the placenta and enter the fetal circulation, (ii) a strong correlation (r ≥0.50; p<0.0001) between the maternal-perinatal particle load (in maternal blood (n=60), term placenta (n=60), and cord blood (n=60)) and residential ambient black carbon exposure during pregnancy, and (iii) the presence of black carbon particles in first and second trimester tissues (fetal liver (n=36), lung (n=36), and brain (n=14)) of electively terminated normally progressing pregnancies from an independent study. Conclusions: This study provides, to the best of our knowledge, the first conclusive evidence that maternally inhaled carbonaceous air pollution particles can cross the placenta and then translocate into human fetal organs during gestation. Further research is now needed to assess their direct effects on fetal organ development and unravel the complexity of particulate air pollution-related health effects in early life. Keywords: ecotoxicology, developmental toxicology, epidemiology, air pollution particle exposure