Now unborn babies are directly exposed to the black carbon generating from fuel burning and motor traffic as air pollution particles have been detected in the foetal side of placentas.
It is for the first time that research shows that particles breathed in by the mother can penetrate the placental barrier. In every placenta analysed, it found thousands of the tiny particles per cubic millimetre of tissue.
The relationship between exposure to dirty air and increased miscarriages, premature births and low birth weights is well established. As per the research, the particles are identified to be the cause, not solely the inflammatory response produced in mothers by the pollution.
Air pollution causing damage to foetuses has lifelong consequences. Prof Tim Nawrot at Hasselt University in Belgium, who led the study, said: “This is the most vulnerable period of life. All the organ systems are in development. For the protection of future generations, we have to reduce exposure.” He said governments were responsible for cutting air pollution; however, when possible people should avoid busy roads.
As per the conclusion of a comprehensive global review, air pollution may be harming every organ and virtually every cell in the human body. Billions of nanoparticles have been found in the hearts of young city dwellers and also found to cross the blood-brain barrier.
Around 90% of the world’s population dwells in places with air pollution above the World Health Organization (WHO) guidelines. Air pollution is reducing in some nations. However, the harm caused by even low levels has been evidenced to be increasing rapidly.
The placentas from 25 non-smoking women in the town of Hasselt examined in the research, published in the journal Nature Communications. Although the particle pollution levels found well below the EU limit but were still above the WHO limit. Researchers detect black carbon particles having a unique light fingerprint using a laser technique.
Each time nanoparticles were found on the foetal side of the placenta and the number correlated with air pollution levels mothers experienced. The mothers living near main roads were having an average of 20,000 nanoparticles per cubic millimetre in the placentas. For those living further away, the average was 10,000 per cubic millimetre.
The placentas from miscarriages were also examined, and the particles were found even in 12-week-old foetuses. In September 2018, the first report of possible pollution particles in placentas was presented at a conference, though the composition of the particles had not been confirmed.
According to Nawrot, it was very likely the foetuses were exposed because the particles were detected on the foetal side of the placental barrier. The analysis of foetal blood for particles is now under process to see if the particles cause damage to DNA.
The black carbon particles were also found in the urine of primary school children by the team. An average of 10 million particles per millilitre detected in hundreds of nine-to-12-year-olds tested, located in the study, published in 2017. “It shows there is translocation of particles from the lungs to all organ systems,” said Nawrot.
“It is really difficult to give people practical advice because everyone has to breathe,” he said. “But what people can do is avoid busy roads as much as possible. There can be very high levels next to busy roads, but just a few meters away can be lower.”
Prof Jonathan Grigg’s group presented the first report of particles in five placentas in September and welcomed the research saying the group’s work had since been expanded and would be published soon.
“We see evidence of particles in all women – it is not like it is a one-off,” said Grigg at Queen Mary University of London in the UK. “It implies that every day we have these very small particles moving around our bodies.”
“We should be protecting foetuses and this is another reminder that we need to get [air pollution] levels down,” he said. “But people shouldn’t be totally scared.” He said as the total weight of the tiny particles was small, more research was needed to find their impact. However, he advised people to use public transport and lower pollution transport options rather than cars.
Grigg said: “This new field of research certainly focuses our attention on the direct role of particles getting to the tissues, rather than particles getting into the lungs and releasing other [inflammatory] substances.”
The research on air pollution now shows that it causes damages from heart and lung disease to diabetes and reduced intelligence to damaged skin and brittle bones. The WHO calls air pollution a “public health emergency” and recent analysis shows 8.8 million early deaths each year, though scientists suspect even this may be “the tip of the iceberg”.