Once again research is finding effects on health from nanoparticles and air pollution - this time the heart. Tiny air pollution particles less than 100 nm (nanometers) in size are typically called "ultrafine particles", but actually they are so small that they are nanoparticles. They are NOT regulated in the United States, even though many researchers feel that they are the most dangerous particles found in air pollution. This is because their small size means they are easily inhaled and then get into human lungs and organs, and even cells. Where do they come from? They get into the air from industry (e.g. metal processing, power generation plants), from the exhaust of vehicles (from vehicle combustion), and from friction when using vehicle brakes.
The researchers write that the air in polluted urban areas and next to roads have a lot of these iron-rich nanoparticles from vehicle combustion and friction. And also that these particles are "strongly magnetic". Earlier research in the urban Mexico City area found that these nanoparticles were found in the brains of all people, starting at young ages (they had died suddenly in accidents, which is why the brains could be analyzed). Keep in mind that Mexico City has high levels of air pollution, but so do many other urban areas throughout the world.
This latest study from a team of international researchers analyzed both the hearts of young people who died suddenly, as well as animals - and they compared the results from those exposed to high levels of urban air pollution (Mexico City metro area) and those from areas with low amounts of air pollution (the "controls"). The results were not good: all hearts from the Mexico City area (high air pollution) had lots of the same iron-rich magnetic nanoparticles ("in abundance") that are found in the air. Billions of nanoparticles in each heart, even in the youngest 3 year old child!
These nanoparticles are inhaled, then enter the person's circulatory system (carried by blood cells), and then into cardiac cells. As the researchers stated: the magnetic nanoparticles were "highly abundant in left ventricular samples from young subjects exposed to high concentrations of particulate air pollution above current US EPA standards. The organelles and structures containing abundant nanoparticles displayed substantial abnormality". Hearts from low pollution areas appeared normal.
This could explain why people living in polluted urban areas, including in the United States, have a greater risk for heart disease (cardiovascular disease), including heart attacks and strokes, as well as premature death. This research also highlights why we need to regulate these tiny particles in the air. As the researchers said: "This is a serious public health concern".
Excerpts from The Guardian: Billions of air pollution particles found in hearts of city dwellers
The hearts of young city dwellers contain billions of toxic air pollution particles, research has revealed. Even in the study’s youngest subject, who was three, damage could be seen in the cells of the organ’s critical pumping muscles that contained the tiny particles. The study suggests these iron-rich particles, produced by vehicles and industry, could be the underlying cause of the long-established statistical link between dirty air and heart disease.
The scientists said the abundance of the nanoparticles might represent a serious public health concern and that particle air pollution must be reduced urgently. More than 90% of the world’s population lives with toxic air, according to the World Health Organization, which has declared the issue a global “public health emergency”.
Maher and colleagues found in 2016 that the same nanoparticles were present in human brains and were associated with Alzheimers-like damage, another disease linked to air pollution.
While all ages were affected, Maher said she was particularly concerned about children. “For really young people, the evidence is now of very early-stage damage both in the heart and the brain,” she said. “We have a likely candidate [particles] able to access both organs, with the pathological evidence to show damage is happening.”
A recent comprehensive review concluded that air pollution may be damaging every organ and virtually every cell in the human body, as tiny particles are inhaled, move into the blood stream and are transported around the body. Much of the evidence of harm, from diabetes to reduced intelligence to increased miscarriages, is epidemiological, as harmful experiments on people are unethical. But one study in 2018 found air pollution particles in the placentas of women who had given birth.
The new research is the first direct evidence that iron-rich nanoparticles may cause heart disease. Tiny particles were already known from laboratory tests to be seriously damaging to human cells and to be a significant component of roadside air pollution.
The research, peer reviewed and published in the journal Environmental Research, analysed heart tissue taken from 63 young people who had died in road traffic accidents but had not suffered chest trauma. They lived in Mexico City, which has high air pollution, and had an average age of 25.
The research was conducted in two main parts: calculating the number of iron-rich nanoparticles present; and looking at their location within the tissue and the associated damage. The number of particles found was between 2bn and 22bn per gram of dried tissue; and their presence was two to 10 times higher in the Mexico City residents than in nine control subjects who had lived in less polluted places.
The medical scientists in the team reported that “exposure to [nanoparticles] appears to be directly associated with early and significant cardiac damage”. Maher said the results were relevant for all countries: “There is absolutely no reason to expect this would be different in any other city.” Based on previous work, she said, the particles were also likely to carry additional contaminants. “We can imagine these nanoparticles come loaded with a toxic mix.”