Early-life development is critical for a healthy development, and any exposure to pollutants or contaminants can be extremely dangerous. Now, a new study has found that black carbon particles can reach the fetal side of the placenta if women are exposed to pollution during pregnancy.

Black carbon is an air pollutant produced by gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuel. It’s basically pure carbon — a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter) — one of the most dangerous types of pollution.

In 2015, alone, small particulate matter was estimated to cause 4.2 million of deaths worldwide — of which 202,000 children younger than 5 years. Children are at much higher risk from pollution because their immune systems are not fully developed yet. During the in utero phase, the organism is even more vulnerable to the effects of pollution. This is why the discovery of black carbon in the placenta is so concerning.

The placenta provides oxygen and nutrients to the growing baby. It also helps with removing waste products from the baby’s blood. It’s not clear whether the carbon particles have reached the fetus — it’s quite plausible, but the exact exposure remains to be addressed in future studies.

Tim Nawrot, a researcher working at Hasselt University and Leuven University, wanted to assess whether black carbon can reach the placenta. Along with colleagues, they used high-resolution imaging on placental samples from 28 women, five of which had given birth pre-term. The presence of BC particles could be identified in all the sampled placentas. Furthermore, the mothers who had been exposed to higher levels of pollution also had more black carbon particles in their placenta.

“Our results demonstrate that the human placental barrier is not
impenetrable for particles. Our observation based on exposure
conditions in real-life is in agreement with previously reported
ex vivo and in vivo studies studying the placental transfer of
various nanoparticles,” the authors write.

“In conclusion, our study provides compelling evidence for the
presence of BC particles originating from ambient air pollution in
human placenta and suggests the direct fetal exposure to those
particles during the most susceptible period of life.”

It’s not the first time the negative effects of pollution on pregnancy have been detailed. Previous research has found that carbon pollution is associated with pre-term births or low birth weights, as well as a swarm of long-term health issues.

“Numerous studies have indisputably demonstrated that particulate inhalation results in health problems far beyond the lungs,” the researchers emphasize in the study.