Researchers in London discovered pollution particles and low amounts of metals inside the placentas of 15 healthy women, a find the team is calling “surprising.”
Upon further analysis, the researchers learned that the particles originated from traffic-related sources such as vehicle brake-wear and the burning of fossil fuels, suggesting the risk to pregnancies is increasing as air pollution is expected to surge over the years.
The placenta develops in the uterus during pregnancy and provides oxygen and nutrients to fetuses through the umbilical cord. It also helps remove waste products from the baby’s blood.
Although it remains unclear if fetuses themselves are affected by the particles, the researchers say bits of pollution are taken up by cells that are important for placental function, meaning there’s a chance fetuses might be exposed to them. Further research is needed to connect the dots, the team said.
The study was published Sept. 12 in the journal Science of the Total Environment.
“Our study for the first time shows that inhaled carbon particulate matter in air pollution, travels in the bloodstream, and is taken up by important cells in the placenta,” study lead author Jonathan Grigg, a professor of paediatric respiratory and environmental medicine at Queen Mary University of London, said in a news release last week.
“We hope that this information will encourage policy makers to reduce road traffic emissions in this post lock down period,” Grigg added.
Past studies have shown that exposure to air pollution while pregnant can cause preterm birth and low birth weight, but how that happens within the body has been unclear.
The team said they were surprised when they found black particles in the donated placentas from all 15 women they studied because the lungs are particularly good at blocking foreign substances from traveling to other organs.
It’s likely because most of the women had exposure to particulate matter at levels above a limit set by the World Health Organization meant to reduce pollution-related deaths, the researchers said.
Particulate matter is a mixture of solid and liquid droplets suspended in the air that are made up of dirt, smoke, dust or soot. They can be large enough to be seen with the naked eye or tiny enough to slip into your lungs and bloodstream unnoticed. Such pollution can be emitted from construction sites, unpaved roads, fields, smokestacks or fires.
To find these tiny particles, the team used light and electron microscopy, X-rays and magnetic analyses on the placental cells. The majority were carbon-based, according to the researchers, but some trace amounts of metals such as “silica, phosphorus, calcium, iron and chromium, and more rarely, titanium, cobalt, zinc and cerium” were found as well.
A previous paper published last year also detected black carbon lodged in placentas, but the new study reveals for the first time what the black particles are made of, a spokesperson for the Queen Mary University of London told McClatchy News in an email.