Questions have been raised over the impact of engineered nanoparticles on human health after an experiment involving chickens has shown that nanoparticles have a 'remodelling' effect on the intestinal villi (picture here in the top half of image), which are microscopic finger-like projections that play an important role in absorbing nutrients.
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PARIS: Tests involving chickens have raised questions about the impact on health from engineered nanoparticles, the ultra-fine grains commonly used in drugs and processed foods.
Chickens exposed to high oral doses of polystyrene particles 50 nanometres across (or 50 billionths of a metre) absorbed less iron in their diet, according to a new study published in Nature Nanotechnology today.
At the same time, birds that were chronically exposed to these doses had a 'remodelling' of their intestinal villi, which are the microscopic finger-like projections that play an important role in absorbing nutrients. The changes meant that the villi increased the surface area available for taking in iron.
Intestinal uptake of calcium, copper, zinc and vitamins A, D, E and K may also be affected by high exposure to nanoparticles, according to the team led by Michael Shuler of Cornell University in New York, although further research is needed to investigate this.
Chronic, but subtle, response
The team tested the particles on chickens as a substitute for the human intestine and also used lab-dish cells from the lining of the human gut. The chickens were given roughly the same dose, weight for weight, as an adult human in a developed country.
According to the researchers, "The intestinal epithelial layer represents the initial gate that ingested nanoparticles must pass to reach the body. The polystyrene particles used in these experiments are generally considered non-toxic, but their interaction with a normal physiological process suggests a potential mechanism for a chronic, harmful, but subtle response."
A role in Chron's disease?
Engineered nanoparticles are used increasingly in the form of titanium oxide or as aluminium silicates in pills to help deliver pills and in food, where they are used as stabilisers or anti-caking agents in fluids and creams.
In developed countries, individuals may be consuming each day a thousand billion engineered particles ranging from fine to ultrafine in scale, according to figures from 2002 research. Previous research has suggested micron- and nano-sized particles could play a role in the painful inflammatory gut disorder called Crohn's disease, the researchers said. Most of these particles have a negatively-charged surface, which means they adhere to biomolecules in the gut, accumulating at lymphoid nodules called Peyer's patches.
