Researchers at Lancaster University in the UK 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.
Professor Barbara Maher, from Lancaster Environment Centre, used spectroscopic analysis to identify the particles as magnetite.
Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nanometres (nm), some with fused surfaces, pointing to high-temperature formation – such as from vehicle engines or open fires.
The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.
“The particles we found are strikingly similar to the magnetite nanospheres 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,” said Maher.