Air pollution gets closer to a fetus than scientists had realized, study suggests

A new study suggests that when a pregnant woman breathes in air pollution, it can travel beyond her lungs to the placenta that guards her fetus.

Pollution composed of tiny particles from sources like auto exhaust and factory smokestacks is dangerous to everyone’s health, and particularly for a developing fetus. Exposure to air pollution during pregnancy has been linked to premature births and low birth weight, but scientists don’t understand why. One theory is that the particles lodge in the mother’s lungs and trigger potentially harmful inflammation.

The study published Tuesday in Nature Communications offers another possibility, and suggests that the link might be more direct.

Using a novel scanning technique, Belgian researchers spotted a type of particle pollution — soot-like black carbon — on placentas donated by 28 new mothers.

The placenta nourishes a fetus as it grows and tries to block damaging substances in the mother’s bloodstream. The researchers found the particles accumulated on the side of the placenta closest to the fetus, near where the umbilical cord emerges.

That’s not proof the soot actually crossed the placenta to reach the fetus, or that it’s responsible for any ill effects, said Dr. Yoel Sadovsky of the University of Pittsburgh Medical Center, a leading placenta expert who wasn’t involved with the new research.

And it’s a small study.

Still, “just finding it at the placenta is important,” Sadovsky said. “The next question would be how much of these black carbon particles need to be there to cause damage.”

Scientists already had some clues from animal studies that particles could reach the placenta, but the new report is a first with human placentas. The Belgian researchers developed a way to scan placenta samples using ultra-short pulses from a laser that made the black carbon particles flash a bright white light so they could be measured.

The study included placentas from 10 mothers who lived in areas with high pollution and 10 others from low-pollution areas. The higher the exposure to pollution, the more particles the researchers counted in the placentas.

“As the fetal organs are under full development, this might have some health risks,” said environment and public health specialist Tim Nawrot, the study’s senior author at Hasselt University in Diepenbeek, Belgium. He said he is doing additional research to try to find out.