Magnetites are microscopic magnetic iron oxides and are by-products of air pollution. These oxides have been discovered lodged in the brain and researchers now believe it is a possible cause of Alzheimer's disease.

Researcher Barbara Maher, from Lancaster Environment Centre, and colleagues from Oxford, Glasgow, Manchester, and Mexico City, found abundant magnetite nanoparticles in the brain tissue from 37 individuals aged three to 92-years-old who lived in Mexico City and Manchester.

This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer's disease. The team used spectroscopic analysis to identify the particles as magnetite.

In 2008, a team led by professor Jon Dobson of Keele University in Staffordshire, UK, first found raised levels of magnetic iron oxides in the areas of the brain commonly affected by Alzheimer’s disease.

Shocking findings of the effects of pollution in the brain

Although magnetite is believed to be formed naturally in our brains in an angular form, most of the observed particles were spherical, with some sporting fused surfaces. These can only be formed in a high-temperature environment, and examples of which are from vehicle (particularly diesel) engines or open fires, which are known causes of pollutants.

Other particles that were found include nano-sized metals, such as platinum, nickel, and cobalt. These foreign particles sport diameters up to 150 nm.

Of note is that particles smaller than 200 nm are able to enter the brain directly through inhalation of air pollution. These particles were also more prominent in females than in males, suggesting a gender-based difference in the way the body handles iron.

A link to Alzheimer’s

"Our results indicate that magnetite nanoparticles in the atmosphere can enter the human brain, where they might pose a risk to human health, including conditions such as Alzheimer's disease," said Professor Maher on the health effects of air pollution.

Leading Alzheimer's researcher Professor David Allsop, of Lancaster University's faculty of health and medicine was excited of this new finding as "(it) opens up a whole new avenue for research into a possible environmental risk factor for a range of different brain diseases."

In those diagnosed with Alzheimer’s, another study has found consistently higher level of concentrations of magnetite, with female Alzheimer’s patients showing a higher concentration as compared to all groups. This means that the presence of magnetite could be used as a biomarker to diagnose Alzheimer’s.

Common sources of air pollution

Maher elaborated that "the particles we found are strikingly similar to the magnetite nanospheres (sic) that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes." Other sources include open fires and poorly sealed stoves within homes.

The World Health Organisation also notes that air pollution can increase the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma. The cleaner the air, the better the cardiovascular and respiratory health of the population will be, in both the long- and short-term. MIMS

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