Black carbon particles have been found on the fetal side of the placenta of women exposed to air pollution during pregnancy, finds an observational study involving 28 women published this week in Nature Communications. Further research is needed to determine whether the particles are able to reach the fetus.
Black carbon particles are released every day into the ambient air, in large part from the combustion of fossil fuels. Such particles are understood to have detrimental effects on pregnancy outcome; for example, they are correlated with pre-term births or low birth weights. Understanding how these particles affect pregnancy - through direct effects on the fetus or indirect effects through the mother - is required to improve pregnancy care in polluted areas.
Tim Nawrot and colleagues provide evidence that black carbon particles can reach the fetal side of the placenta during pregnancy. Using high-resolution imaging, they were able to detect black carbon particles in placentae collected from five pre-term and 23 full-term births. The authors found that ten mothers who had been exposed to high levels of residential black carbon particles (2.42 micrograms per m3) during pregnancy had higher levels of particles in the placenta than ten mothers who had been exposed to low levels of residential black carbon (0.63 micrograms per m3).
Additional research is required to understand whether the accumulation of black carbon particles in placental tissue may be responsible for the adverse effects associated with air pollution exposure during pregnancy.
In an accompanying review article published in the journal Clinical Epigenetics, Tim Nawrot and colleagues provide an overview of molecular alterations in the placenta, including epigenetic changes, caused by air pollution.
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