LOS ANGELES: Airborne carbon particles that can cause health problems in adults and children are getting into the placenta as it nourishes a developing foetus, a new study has found.
Tissue samples from five pre-term and 23 full-term births found that the more airborne soot the mother was exposed to during pregnancy, the higher the number of so-called black carbon particles found in the placenta, researchers report in Nature Communications.
In addition to transferring oxygen and nutrients from the mother to the foetus, the placenta is supposed to be a barrier - albeit not a perfect one - that protects the foetus from substances that might harm it.
Dr Frank Gilliland of the University of Southern California's Keck School of Medicine, who was involved in the study, characterised the findings as "pretty remarkable".
"Our results demonstrate that the human placental barrier is not impenetrable for particles," said the team, led by Tim Nawrot of Hasselt University in Belgium.
Whether those particles, created by the combustion of fossil fuels, pose a direct risk to the foetus is an unresolved question. But the researchers speculate that the pollutants may play a role in the low birth weight or premature delivery more often seen in babies whose mothers are exposed to higher levels of contaminated air.
"This builds on a growing body of evidence that these particles are actually absorbed and distributed throughout the human body, said Dr Gilliland, a professor of preventive medicine in Keck's Division of Environmental Medicine.
"We know the foetus is in a vulnerable state so these things sitting there in the placenta can't be good," he said. "They may be inert, but the chances are they are playing a role in some of the adverse effects regarding growth and development that we see in particulate pollution."
"It opens up a whole additional line of research to understand the effects these particles are having on the foetus," he said.
Such particles have been known to slow cognitive abilities, and they've been seen in the urine of healthy children and in the brain at autopsy.
The Nawrot team found the black carbon (BC) particles on both sides of the placentas, regardless of whether the baby was born early.
"Further research will have to show whether the particles can cross the placenta and reach the foetus, and if particle translocation is responsible for the observed adverse health effects during early life," the researchers said.
Nawrot did not respond to requests for comment.