The idea that air pollution can hurt developing fetuses in the womb is not controversial. But new preliminary research presented this week seems to provide direct evidence of how this damage can happen, via the placenta.
The UK researchers studied the placentas of five non-smoking women who had recently given birth to healthy children through cesarean section. Hoping to confirm that soot could move from a person’s lungs to their bloodstream and then to the placenta, they looked for a specific type of immune cell, known as a macrophage. In earlier research, the team developed a technique using a microscope to identify pollution particles, made out of carbon, inside macrophages found in the lung.
Macrophages carry out lots of jobs, one of which is to swallow up dangerous foreign particles from things like bacteria and pollution. They also serve as one of the lines of defence for the fetus.
When the team used the same technique on the 3,500 placental macrophages they had collected from the women, they found these black carbon particles in 60 of them. And when they looked at two placentas with a higher-powered electron microscope, they again found these particles. Each placenta, on average, had about five square micrometres of the particles.
“Our results provide the first evidence that inhaled pollution particles can move from the lungs into the circulation and then to the placenta,” said Norrice Liu, a paediatrician and clinical research fellow at Queen Mary University of London, in a statement.
The team’s findings were presented Sunday at the European Respiratory Society International Congress.
Because the research hasn’t been formally peer-reviewed and published in a journal yet, it shouldn’t be accepted uncritically. And the researchers, as even they admit, still didn’t show any direct harm caused by these pollution particles. But the chances of harm aren’t exactly in dispute.
“We do not know whether the particles we found could also move across into the fetus, but our evidence suggests that this is indeed possible,” said Liu. “We also know that the particles do not need to get into the baby’s body to have an adverse effect, because if they have an effect on the placenta, this will have a direct impact on the fetus.”
Plenty of studies elsewhere have shown that air pollution exposure in developing fetuses is linked to all sorts of health problems later on in life, including low birth weight, autism spectrum disorder, and obesity.
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