Air Pollution Nanoparticles, Including Metals, Are Reaching the Placental Tissue Cells
Mon, October 25, 2021

Air Pollution Nanoparticles, Including Metals, Are Reaching the Placental Tissue Cells


Air pollution is a combination of various gases and airborne particles in sizes of few nanometers to micrometers. The World Health Organization has previously mentioned that the presence of atmospheric nanoparticles (size range in the nanometer scale, such as below 100 nm) has harmful effects on the environment and human health. They may be immediately absorbed by humans as they enter the fluids and tissues of the body. The potentially harmful effects known may include lung inflammation and heart problems.

Nanoparticles found in the human placenta

A recent study, which appeared in the journal Science of The Total Environment, likewise shows that air pollution particles, including metals, are reaching the placental tissue cells. The study led by the Queen Mary University of London found that pollution particles are present in the placentas of 15 women in London. The inhaled particulate matter from air pollution can reach the placentas from the lungs to distant organs. Then, it will be carried by certain cells in the human placenta. There is also a possibility that it can reach the fetus.

Particle size: why is it an important parameter?

In previous research titled “Atmospheric Nanoparticles and Their Impacts on Public Health,” authors Klara Slezakova and colleagues have also emphasized the danger of nanosized particles. They explained that particle size is an important parameter because it controls the dynamic behavior of the particles and their physical and chemical impacts upon the environment.

It likewise is certainly a significant parameter for the health consequences of the respective human exposure as particle size determines the amount of surface area that contact tissues, the deposition of the nanoparticles within the human respiratory system, and the rate of particle clearance from the lungs.

The particles have irregular shapes, which affect their aerodynamic behavior. The coarse mode of the particles can likewise be further subdivided into coarse and super coarse particles.  The coarse particles, which usually have a diameter between 2,500 nm and 10,000 nm, are often produced by mechanical processes like wind erosion, Slezakova and team added.

Analyzing the placentas of 15 consenting women

As for the recent study led by the Queen Mary University of London, authors Norrice M. Liu from the Centre for Genomics and Child Health and team analyzed the placentas from 15 consenting healthy women. These organs were donated to the study after the birth of their kids at the Royal London Hospital. The team sought to seek evidence for air pollution-derived particulate matter (PM).

Thirteen women in the study had exposure above the annual mean limit of WHO for particulate matter. The tissue cells in the placenta were analyzed by the team using various techniques, such as magnetic analyses, x-rays, and electron and light microscopy. The team identified black particles that are morphologically compatible with inhaled PM from all 15 placentas and these show in an average of 1% of cells analyzed. Most of the particles they found in placental tissue cells were carbon-based yet the team also discovered trace amounts of metals, including phosphorus, silica, iron, chromium, iron, calcium, and zinc. They also found more rarely cerium, zinc, cobalt, and titanium.



Nanoparticles from traffic-related sources

Most of these nanoparticles originated from traffic-related sources. Most of these metals are even linked with fuel combustion arising from oil additives and fuel and vehicle break-wear. Lead author Professor Jonathan Grigg told Science Daily that their study is the first to show that inhaled PM in air pollution travels in the bloodstream of women and reach the placenta.

The team hopes that their findings will encourage policymakers to lessen road traffic emissions, especially after the pandemic lockdown. Liu also said that air pollution levels in London usually exceed the yearly limits. Their team also shares the link between maternal exposure to high levels of pollution and problems with the fetus. These problems include the risk of low birth weight. Yet, before their findings, science has limited insight into how it may happen in the body.

For a while, the team has already thought that maternal inhalation of air pollution could result in particles traveling to the placenta. Yet, the lungs have defense mechanisms that prevent foreign particles from traveling in other organs of the body. This is why they were surprised to identify the nanoparticles in the placental tissue cells from all of their participants.

England-based nonprofit Barts Charity’ Chief Executive Fiona Miller Smith opined that the study is “incredibly important” and immensely relevant for moms-to-be in their local community. The findings will also be helpful for pregnant women anywhere else in the world, especially if they are living in the urban community.

Risk of air pollution to the unborn baby

The team continued that although it can be difficult to see beyond pandemic now, they hope that their findings will lead to greater awareness of the risk of air pollution to the unborn baby. Other researchers of the study come from the University of Leeds, the University of Oxford, University of Birmingham, King’s College London, Central Manchester University Hospital NHS Foundation Trust, University of Manchester, and Barts Health NHS Trust.

According to The Organization for Economic Co-operation and Development, an intergovernmental economic organization founded to stimulate economic progress and world trade, countries with the highest exposure to fine particulate matter (PM2.5) in 2014 includes Botswana, Burkina Faso, Burundi, Central African Republic, Chad, Eswatini, Ethiopia, Gambia, Hungary, Iraq, Jordan, Lao People's Democratic Republic, Lesotho, and Malawi. A total of 100% of their population are exposed to PM 2.5 fine particles, the OECD added.

On the other hand, countries with the lowest exposure to PM 2.5 includes Brunei Darussalam (0.00%), Finland (0.00%), New Zealand (0.34%), Estonia (0.73%), Canada (2.64%), Sweden (3.17%), Norway (3.93%), Ireland (6.02%), and Iceland (6.38%).



In Ontario, Pm 2.5 is primarily formed in the residential sector (39%), other transportation (19%), other PM 25 industrial processes (15%), smelters or primary metals (11%), cement and concrete industry (5%), and road vehicles (3%).

The WHO also said that air pollution contributes to about 4.2 million deaths every year with 91% of the world population living in locations where it is greater than their guidelines.

The ability of nanoparticles to travel through a pregnant woman’s body and potentially through the baby could be a wake-up call to all of us to reduce air pollution in our little ways. Small changes in your driving habits, for instance, can make a big difference.