When pollution particles get into your brain...

The Hindu , Thursday, September 08, 2016
Correspondent : DAVID SHUKMAN
Tiny particles of pollution have been discovered inside samples of brain tissue, according to new research.

Suspected of toxicity, the particles of iron oxide could conceivably contribute to diseases like Alzheimer’s - though evidence for this is lacking.

The finding - described as “dreadfully shocking” by the researchers - raises a host of new questions about the health risks of air pollution.

Many studies have focused on the impact of dirty air on the lungs and heart.

Now this new research provides the first evidence that minute particles of what is called magnetite, which can be derived from pollution, can find their way into the brain.

Tracing origins

The research was led by scientists at Lancaster University and is published in the Proceedings of the National Academy of Sciences (PNAS).

The team analysed samples of brain tissue from 37 people - 29 who had lived and died in Mexico City, a notorious pollution hotspot, and who were aged from 3 to 85.

The other 8 came from Manchester, were aged 62-92 and some had died with varying severities of neurodegenerative disease.

The lead author of the research paper, Prof Barbara Maher, has previously identified magnetite particles in samples of air gathered beside a busy road in Lancaster and outside a power station.

She suspected that similar particles may be found in the brain samples, and that is what happened.

“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.”

Further study revealed that the particles have a distinctive shape which provides a crucial clue to their origin.

Magnetite can occur naturally in the brain in tiny quantities but the particles formed that way are distinctively jagged.

By contrast, the particles found in the study were not only far more numerous but also smooth and rounded - characteristics that can only be created in the high temperatures of a vehicle engine or braking systems.

For every one natural magnetite particle identified, the researchers found about 100 of the pollution-derived ones.

Disease risk?

Dubbed “nanospheres”, the particles are less than 200 nanometres in diameter - by comparison, a human hair is at least 50,000 nanometres thick.

While large particles of pollution such as soot can be trapped inside the nose, smaller types can enter the lungs and even smaller ones can cross into the bloodstream.

But nanoscale particles of magnetite are believed to be small enough to pass from the nose into the olfactory bulb and then via the nervous system into the frontal cortex of the brain.

Prof David Allsop, a specialist in Alzheimer’s and other neurodegenerative diseases, is a co-author of the study and also at Lancaster University.

He said that pollution particles “could be an important risk factor” for these conditions.

“There is no absolutely proven link at the moment but there are lots of suggestive observations - other people have found these pollution particles in the middle of the plaques that accumulate in the brain in Alzheimer’s disease so they could well be a contributor to plaque formation.”

“These particles are made out of iron and iron is very reactive so it’s almost certainly going to do some damage to the brain. It’s involved in producing very reactive molecules called reaction oxygen species which produce oxidative damage and that’s very well defined.” “We already know oxidative damage contributes to brain damage in Alzheimer’s patients so if you’ve got iron in the brain it’s very likely to do some damage. It can’t be benign.”NYT

 
SOURCE : http://www.thehindu.com/todays-paper/tp-in-school/when-pollution-particles-get-into-your-brain/article9082233.ece
 


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