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Soot Found In Fetus Lungs, Brains, And Placentas During Early Pregnancy

"We all worried that if nanoparticles were getting into the fetus, then they might be directly affecting its development in the womb."


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

A facemask being held over a pregnant belly
Ok this is incorrect for like, four different reasons. Image: Nazar Skladanyi/Shutterstock

Today’s humans are exposed to black carbon particles not only from air pollution after birth, but as early as the first trimester of their gestation, new research has revealed.

“We found black carbon particles in human cord blood, which provides evidence of their transfer to the fetal circulation system,” explains the paper, published this month in The Lancet, “and we further corroborated this finding by also identifying these particles in fetal tissue samples from electively terminated, normally progressing pregnancies.” 


These particles turned up throughout the fetal bodies, being found in their liver, lung, and brain tissues, plus the placenta. While the highest concentration of black carbon was found in this last organ – which makes sense since the placenta acts as a barrier against harmful microbes and particles reaching the fetus – the fact that any were found at this crucial stage is worrying, the researchers say.

“We all worried that if nanoparticles were getting into the fetus, then they might be directly affecting its development in the womb,” explained Paul Fowler, Chair in Translational Medical Sciences at the University of Aberdeen and co-author of the paper, in a statement

“What we have shown for the first time is that black carbon air pollution nanoparticles not only get into the first and second trimester placenta, but then also find their way into the organs of the developing fetus, including the liver and lungs,” he said. 

Clearly, none of us want black carbon in our organs. Exposure to this ubiquitous pollution has been linked to cardiovascular and respiratory problems, and is known to contribute to premature death. However, its presence so early is “especially concerning,” the paper notes, as it means that these particles are interacting with human organs before they’re even finished developing.


“What is even more worrying is that these black carbon particles also get into the developing human brain,” Fowler added. “This means that it is possible for these nanoparticles to directly interact with control systems within human fetal organs and cells.”

This is hardly the first study to find evidence of air pollution crossing the placental barrier, but this is the first time black carbon particles have been confirmed to make it into fetal organs. Perhaps even more disturbingly, this crucial developmental window isn’t just contaminated by the pollutant particles – the researchers actually found evidence that maternal-fetal transfer of black carbon may peak within the first and second trimesters.

While we don’t yet fully understand why black carbon is so dangerous –  it’s thought in part to be due to the chemical coating that results from combustion – there’s no doubt that this is bad news for pregnant people and babies. 

“We know that exposure to air pollution during pregnancy and infancy has been linked with still birth, preterm birth, low weight babies and disturbed brain development, with consequences persisting throughout life,” said Tim Nawrot, professor of environmental epidemiology at Hasselt University's Centre for Environmental Sciences, and study co-author.


“We show in this study that the number of black carbon particles that get into the mother are passed on proportionally to the placenta and into the baby,” he explained. “This means that air quality regulation should recognize this transfer during gestation and act to protect the most susceptible stages of human development.” 


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  • tag
  • development,

  • pollution,

  • pregnancy,

  • health,

  • soot,

  • black carbon,

  • fetuses