Abnormal levels of air pollution particles found deposited in brain tissue
Jonathan Nackstrand (AFP)
Researchers have discovered that particles from air pollution become deposited in brain tissue, BBC News reports.
A study conducted by scientists at England's Lancaster University studied brain tissue samples from 37 donors and found abnormal levels of magnetite particles, the same type of particles found in air pollution. The research also pointed towards a possible link between the particles and Alzheimer's disease.
The subjects in the study came from two areas—29 from notoriously polluted Mexico City and eight from Manchester.
The ages of the donors from Mexico ranged from three to 85 years, while those from Manchester were between 62 and 92 years of age. Some of the Manchester donors had suffered from neurodegenerative disease, said the BBC.
Previous researched has exposed the affects of air pollution on the lungs heart, and a study published by the World Health Organization (WHO) last year found that pollution -- especially by tiny particulate matter (PM) that can find its way deep into lungs -- is to blame for 3.2 million preventable deaths every year.
Published in the Proceedings of the National Academy of Sciences (PNAS), the new research found that while some magnetite occurs naturally in the brain, the ratio of naturally occurring particles to those deposit was on average 100 pollution deposited particles for every naturally occurring particle.
Scientists were able to differentiate between the particles that occurred naturally from those that were deposited by their shape. The naturally occurring particles had jagged edges and irregular shapes, while the ones from pollution were round and smooth—a shape obtained after the particles are exposed to high heat, such as that in a vehicle's exhaust system.
“Many of the magnetite particles we have found in the brain are very distinctive,” lead author of the research paper, Prof Barbara Maher told the Guardian newspaper.
“They are very rounded nanospheres, because they were formed as molten droplets of material from combustion sources, such as car exhausts, industrial processes and power stations, anywhere you are burning fuel.”
Magnetite an iron oxide could cause extensive damage to brain tissue in large quantities, the researchers believe. The mineral has the ability to produce free radicals—highly reactive molecules which have an oxidative, or damaging effect on cells.
“Oxidative cell damage is one of the hallmark features of Alzheimer’s disease, and this is why the presence of magnetite is so potentially significant, because it is so bioreactive,” Maher explains.
"It's dreadfully shocking. When you study the tissue you see the particles distributed between the cells and when you do a magnetic extraction there are millions of particles, millions in a single gram of brain tissue - that's a million opportunities to do damage," she adds.
Magnetite was not the only pollution sourced particle
“We also observed other metal-bearing particles in the brain, such as platinum, cobalt and nickel. Things like platinum are very unlikely to come from a source within the brain. It is a bit of an indicator of a [vehicle] catalytic converter source,” Maher told the Guardian.
The study does not provide a definitive link between the particles and the development of Alzheimer's but it does suggest a connection.
“We have not demonstrated a causal link between these particles and Alzheimer’s disease but when you consider that magnetite has been found in higher concentrations in Alzheimer’s brains and you know that magnetite is pernicious in its effect on the brain, then having a direct [air pollution] source of magnetite right up your olfactory bulb and into your frontal cortex is not a great idea,” said Maher.
A study published last September by Israel's Environmental Protection Ministry puts Tel-Aviv and Haifa at the top of the list of cities which have the most air pollution in comparison to European cities.
Jerusalem also made the list, coming in fifth place after Prague and Marseille.
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