Black Carbon Particles Were Found in Placentas of Every Pregnant Woman in This Study—Even Those Not in Highly Polluted Areas

Scientists have found black carbon particles in the placentas of pregnant women—even those who did not live in a highly polluted area.

The authors of the research, published in the journal Nature Communications, identified particles from the sooty black substance on the fetal side of the placentas they studied. This lead them to conclude black carbon can likely travel from the mother's lungs to the organ—which acts as a barrier between the mother and fetus during pregnancy.

Substances like alcohol are already known to pass through the placenta.

Black carbon is given off by fossil fuel-burning sources like vehicles that use gas and diesel, and coal-fired power stations. A component of the air pollutant fine particulate matter, black carbon is linked to heart and breathing problems, as well as diseases such as cancer.

Past studies have also linked the substance with low birth weight and babies being born preterm. The researchers fear particulates could explain these defects.

The team used high-resolution imaging to examine placenta tissue collected from women from the north-east of Belgium. 10 of the women were exposed to high levels of black carbon where they lived, and 10 low levels. A further five placentas came from women who had a spontaneous preterm births.

Mothers were categorised as living in a highly polluted area if their home was located 500 meters (1,640 feet) or less from a major road, and exposed to an average yearly concentration of 2.42 micrograms per meter cubed of fine particulate matter during the year of their pregnancy. A low exposure was defined as 0.63 micrograms per meter cubed.

Tests revealed the women who lived in the highly polluted areas had more black carbon particles in their placentas. But scientists found black carbon in all of the placentas.

More research is needed to determine if the particles are able to get to the fetus, and if this explains the birth defects linked to pollution.

"Although further research is needed, our results suggest that particle transport through placental tissue is indeed possible," the authors wrote.

Andrew Shennan, Professor of Obstetrics, King's College London who did not work on the study, commented: "Small particles, such as through smoking, can cause considerable disease related to the placenta, and these findings of particles in the placenta are a concern. Their possible effects on the baby and mother warrant further investigation.

"The placenta is the interface between mother and baby and is key to nourishing and supporting all the needs of the baby. Both the function and structure of the placenta is important, not only to the baby's growth and wellbeing, but also to that of the mother. High blood pressure and fits in pregnancy have been linked to house hold pollution."

Last month, a separate study found being exposed to air pollution could raise the risk of developing mental illnesses such as bipolar disorder and major depression. The findings were published in the journal PLOS Biology.

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Researchers have found black carbon particles on the placenta of women exposed to air pollution during pregnancy. In this stock image, a pregnant woman holds her stomach. Getty