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Your brain is sponging up toxic nanomagnets from polluted air

Health effects are uncertain, but scientists note a possible link with Alzheimer’s.

Beth Mole
Anyone who’s lived in a smoggy city would likely welcome the idea of using widely dispersed air filters to soak up all those toxic tidbits floating around—unless, of course, those filters were functioning human brains.
Our noggins naturally catch and collect the toxic, magnetic nanoparticles that we inadvertently inhale from polluted air, according to a study published Monday in the Proceedings of the National Academy of Sciences. Those wee particles, made of the strongly magnetic iron oxide compound, magnetite, have been found in human brains before and were thought to be normal and harmless byproducts of biological processes. But according to the new study, a closer examination of minuscule metal balls in 37 human brains revealed that they’re actually from smog, formed during combustion or friction-derived heating, such as slamming on the brakes of a car.
Whether the particles are harmful is hazy, but the authors note that the nanomagnets have two troubling features: they can interact with misfolded proteins associated with Alzheimer’s disease to produce reactive oxygen species, which can severely damage cells; and large amounts of them in the brain correlated with Alzheimer’s disease in earlier studies. Given these potential risks, the authors—a team of researchers from the UK and Mexico—suggest that exposure to them “might need to be examined as a possible hazard to human health.”
Lead author Barbara Maher, physicist and co-director of the Centre for Environmental Magnetism and Paleomagnetism at Lancaster University in the UK, got the idea to examine the brain-embedded particles knowing that magnetite nanoparticles are abundant in air pollution.
Using high-resolution imaging techniques, she and her team examined the nanomagnets in the frontal cortex of 37 human brain samples, donated posthumously. Most samples were from people living in Mexico City with a few donated from Manchester, UK. Close examination showed that some of the brain nanomagnets had angular, geometric shapes—a telltale sign that they formed in biological processes. However, the vast majority of the particles were smooth spheres—the kind that tends to spew from smokestacks and exhaust pipes. Those tiny magnetic balls were also accompanied by other transition metal nanoparticles, namely platinum, nickel, and cobalt. These don’t normally show up in the brain and are often associated with magnetite nanoparticles in pollution.
“The surface textures, size, and size distribution of the spherical magnetites identified in our study, and the co-occurrence of PM-associated transition metal nanoparticles, are all inconsistent with the characteristics of biogenically formed magnetite,” the authors concluded.
Maher and her colleagues speculate that the particles get lodged in our brains after we simply inhale them. They’re so small—around 150 nanometers or less—that they could easily move into the brain directly through any cracks or openings in an olfactory bulb.
“This is an interesting paper which certainly gives evidence that pollution-born magnetite can end up in the brain,” Jennifer Pocock, a neurologist at University College London, said in a statement. “However, I think any correlation with this and Alzheimer’s disease is weak.” Pocock questioned how common or easy it would be for nanomagnets to slip into the brain from the olfactory bulb. She also noted that the study didn’t include a comparison of the nanomagnet collections in brains of people who lived in cities with those of rural folk.
Clare Walton, research manager at the UK-based Alzheimer’s Society, agreed. “This study offers convincing evidence that magnetite from air pollution can get into the brain, but it doesn’t tell us what effect this has on brain health or conditions such as Alzheimer’s disease,” she said in a statement. Like Pocock, she called for more studies into the topic and added that, “until we have more information people should not be unduly worried.”
Proceedings of the National Academy of Sciences, 2016. DOI: 10.1073/pnas.1605941113  (About DOIs).
Your brain is sponging up toxic nanomagnets from polluted air Reviewed by Chidinma C Amadi on 11:17 PM Rating: 5

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