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Study Sheds Light on How Air Pollution can Cause Heart Disease

A new study has confirmed that harmful metallic air pollution nanoparticles are entering the critical, energy-producing structures inside the hearts of people living in polluted cities, resulting in cardiac stress.

Professor Barbara Maher. Image Credit: Lancaster University.

Researchers used advanced electron microscopy to demonstrate, for the first time, that tiny metal nanoparticles are entering the mitochondria of heart tissue—causing damage to such critical “powerhouses” that offer energy for the heart to pump.

A research group, under the guidance of Professors Barbara Maher of Lancaster University and Lilian Calderón-Garcidueñas of The University of Montana and the Universidad del Valle de Mexico, identified the metallic nanoparticles, such as iron-rich nanoparticles and other pollution-derived metals such as titanium, within the degraded heart cells of even a 3-year-old and a 26-year-old.

The hearts were those of people who had lived in highly polluted Mexico City and who had died in accidents.

The study results provide new insights into how air pollution can lead to the development of heart disease, since the iron-rich particles caused damage to the cells, and raised cardiac oxidative stress, even in very young hearts.

The continuous inhalation of such iron-rich nanoparticles, and their circulation by the bloodstream to the heart, could be related to the well-established connections between exposure to particulate air pollution and raised cardiovascular disease, such as heart attacks.

The study demonstrates that heart disease could begin at a very early age, before advancing to full-blown cardiovascular illness in the future. Hence, this kind of air pollution may be responsible for the “silent epidemic” of heart disease, globally.

By leading to pre-existing heart conditions, it may also cause increased death rates from Covid-19 observed in regions with higher levels of particulate air pollution.

It’s been known for a long time that people with high exposure to particulate air pollution experience increased levels and severity of heart disease. Our new work shows that iron-rich nanoparticles from air pollution can get right inside the millions of mitochondria inside our heart, the structures which generate the energy needed for our hearts to pump properly.

Barbara Maher, Professor, Lancaster University

Maher added, “That we found these metal particles inside the heart of even a three-year old indicates that we’re setting heart disease in train right from the earliest days, but only seeing its full, clinical effects in later life. It’s really urgent to reduce emissions of ultrafine particles from our vehicles and from industry before we give heart disease to the next generation too.”

By making use of the energy-dispersive X-ray analysis and high-resolution transmission electron microscopy, the team identified that the mitochondria with the iron-rich nanoparticles seemed to be degraded, with a few cells displaying deformities and others with broken membranes.

According to Professor Calderón-Garcidueñas, raised levels of markers of cardiac oxidative stress exist in the very young cases that have been investigated.

The iron-rich nanoparticles observed within the heart cells are similar in size, shape, and composition to those discharged from sources like the brakes, tires, and exhausts of vehicles. Also, such air pollution nanoparticles are released by open fires in homes and industrial sources.

A few of the iron-rich nanoparticles were also found to be strongly magnetic. This leads to questions about what might happen while people with millions of such nanoparticles in their hearts use appliances with linked magnetic fields, like mobile phones and hair dryers.

People working in industries and exposed to magnetic fields, like welders and power line engineers, may also be at risk. This type of exposure could possibly result in cell damage and heart electrical dysfunction.

The study results are based on the earlier findings of the team that reveal that the hearts of city dwellers comprise billions of such nanoparticles and can be up to 10 times more polluted compared to the hearts of people living in less polluted regions.

According to the team, the study highlights the need for governments worldwide to deal with ultrafine particulate pollution in their cities.

Exposure to such air pollution is a modifiable risk factor for cardiovascular disease, on a global scale, reinforcing the urgent need for individual and government actions not just to reduce PM2.5 but to monitor, regulate and reduce emissions of these specific, ultrafine components of the urban air pollution ‘cocktail’.

Lilian Calderón-Garcidueñas, Professor, University of Montana

The study has been described in the paper titled “Iron-rich air pollution nanoparticles: An unrecognized environmental risk factor for myocardial mitochondrial dysfunction and cardiac oxidative stress,” published online in the Environmental Research journal.

The authors of the paper are Barbara Maher of Lancaster University, U.K., Lilian Calderón-Garcidueñas of Montana University and Universidad del Valle de México, Angelica González-Maciel and Rafael Reynoso-Robles of the Instituto Nacional de Pediatría, México, as well as Ricardo Torres-Jardón of the Universidad Nacional Autónoma de México.

Journal Reference:

Maher, B. A., et al. (2020) Iron-rich air pollution nanoparticles: An unrecognized environmental risk factor for myocardial mitochondrial dysfunction and cardiac oxidative stress. Environmental Research.


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