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New Research Finds Air Pollution Particles Can Reach The Placenta

by Morgan Brinlee

Largely comprised of black carbon particles, soot has long been known as one of the more dangerous forms of air pollution as its microscopic particles can easily enter the lungs and bloodstream and cause a number of serious health issues. Yet soot, or more specifically black carbon, may be particularly troubling to those who are pregnant. A new study on air pollution and pregnancy shows black carbon particles can translocate from the lungs to the placenta.

For decades, it has been known that exposure to air pollution, or more specifically the inhalation of black carbon particles as part of combustion-derived particulate matter, can cause a number of health problems. In fact, the U.S. Environmental Protection Agency has stated that the "inhalation of black carbon is associated with health problems including respiratory and cardiovascular disease, cancer, and even birth defects." Additionally, the World Health Organization has attributed 43 percent of all lung disease and lung cancer to air pollution, noting that it causes 1.8 million deaths a year.

But while researchers have already discovered that maternal exposure to air pollution can impact the birth outcomes and blood pressure of babies, it wasn't altogether clear if particulate matter like black carbon could cross the placenta. Although initially thought to function as an impenetrable barrier that provides oxygen and nutrients to the fetus, scientists have since learned that things like drugs and alcohol can cross the placenta. And a new study recently published in Nature Communications, has found that black carbon particles can indeed reach the placenta. What's more, they can accumulate on the side of the placenta that faces the fetus.

"[Black carbon] particles accumulate on the fetal side of the placenta suggests that ambient particulates could be transported towards the fetus and represents a potential mechanism explaining the detrimental health effects of pollution from early life onwards," the study noted.

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In their study, researchers looked at the placental tissue of 10 mothers who lived in areas with low exposure to black carbon and 10 mothers in areas with high exposure. Ultimately, black carbon particles were found in all of the placentas used in the study, although accumulation was higher in women who lived in more polluted areas. Researchers also tested five placentas from spontaneous preterm births, or miscarriages, and found that black carbon particles were present in the placenta as early as 12 weeks into pregnancy.

The placenta begins to form in roughly week five of a pregnancy, according to What To Expect, and while it continues to grow as the fetus grows, the placenta is considered to have all of the structures it needs by week 12. Meaning, black carbon particles can reach the placenta in its early stages.

Although researchers have now confirmed that black carbon particles can reach the placenta during pregnancy, they have yet to study how, or if, those particles can impact the fetus. So, while past studies have shown a link between air pollution and health conditions such as asthma, it's unclear if an accumulation of particles in the placenta plays a role. Though hopefully more research on this subject is in the works since the black carbon particles in air pollution are hard to avoid as breathing is a vital part of life.