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[NEW DELHI] Inhaled nanoparticles can cross the lungs, entering the bloodstream, and accumulate in blood vessels and other bodily sites vulnerable to cardiovascular disease, a new study suggests. 
People around the world are constantly exposed to nanoparticles mostly emitted by vehicle exhaust, but the risks are greater in crowded Asian cities, which are seeing a dramatic rise in the number of vehicles on the roads.
In the study — the results of which were published on 26 April in ACS Nano it was shown that healthy volunteers exposed to gold nanoparticles retained them in the body for as long as three months. Experiments on mice also reveal that nanoparticles accumulate in the liver and blood vessels.
Results from human studies have been inconsistent thus far, the authors write. But evidence showing that nanoparticles enter the blood circulation by escaping the lungs “provides a direct mechanism that can explain the link between environmental nanoparticles and cardiovascular disease”. It also has implications for managing potential risks of engineered nanoparticles, they add.
The link between environmental nanoparticles and cardiovascular disease could be explained by gold particles detected in surgical specimens of diseased carotid artery from patients at risk of stroke and at sites of vascular inflammation, according to the study.

“A comprehensive toxicology screening needs to be performed with all new nanomaterials, especially with attention to the cardiovascular system.”

Mark Miller, University of Edinburgh 

While it was conducted with gold nanoparticles, the researchers believe that the results can be extended to nanoparticles in vehicle exhaust. 

“This is something we are investigating further in our current research,” says Mark Miller, senior research scientist, University of Edinburgh, UK, and the corresponding author of the study.
Nanoparticles in ambient air come from both natural and artificial sources, but vehicles are the main culprit says Prashant Kumar, professor of air quality and health at the University of Surrey.

“They contribute up to 90 per cent of the total in polluted environments such as busy roads,” he says.  
In Europe, tighter emission norms have reduced the number of nanoparticles emitted by diesel engines. However, the situation is different in developing Asia Pacific countries where older vehicles are still widely used, and the burning of solid fuels for cooking already adds to particulate matter in ambient air. Nanotechnology is expected to touch human lives in many ways, but the risks associated with new engineered nanomaterials are poorly understood.
“A comprehensive toxicology screening needs to be performed with all new nanomaterials, especially with attention to the cardiovascular system,” says Miller.
This piece was produced by SciDev.Net’s Asia & Pacific desk.