Do nanoparticles pose a health risk?

2012-02-23 00:00

THE fruit in the air-tight container looks freshly picked for days and the negligee, as well as the building façade, are guaranteed to stay free of micro-organisms. Nanotechnology, now in almost every industry, makes this possible. Its critics warn of potential health hazards, however.

Unimaginably tiny, a nanometre is equal to a millionth of a millimetre. Nanoparticles are particles with at least one dimension that is 100 nanometres or less in size. What makes them particularly special is their huge surface-area-to-volume ratio.

“Nanotechnology makes it possible to achieve very large effects with a minimal amount of material,” said Dieter Sporn, head of the Smart Materials Centre at the Fraunhofer Institute for Silicate Research in Wuerzburg, Germany. “It’s in demand wherever the thinnest possible layers of material are needed or extremely costly materials are used.”

The chemical and physical properties of materials change depending on the size and geometry of their particles. Nanoparticles can accelerate industrial processes such as the hardening of enamel paint, and they can intensify a chemical’s effects. Different nanomaterials are used for different applications, either as product components or as product coatings.

Nanosilver is used in textiles, wall paint and household appliances like refrigerators for its antimicrobial properties. Structural elements in nanoparticles of silicon dioxide make outdoor fabrics dirt repellent. But the innovations have a downside: the altered properties that make nanomaterials so interesting to researchers may be harmful to humans, animals and the environment.

“Ideally, risk research would be conducted in parallel with product development,” remarked Jan Beringer, a chemist at Germany’s Hohenstein Institute for Textile Innovation.

It is not. Research into possible risks and side effects lags far behind product development and marketing. And although a large number of studies on potential health hazards have been done, “each concerns very specific products only, so the findings’ applicability to other products is limited”, Beringer said. The studies, do, however, point to possible risks.

“Nanoparticles are so small that it’s not exactly known what barriers they can penetrate,” noted Monika Buening, a product safety specialist with the Berlin-based Federation of German Consumer Organisations. “Animal testing has shown that nanoparticles enter the lungs and are transported into the bloodstream and brain, for example.”

Kathrin Schwirn of Germany’s Federal Ministry for the Environment, Nature Conservation and Nuclear Safety added there were indications that substances with toxic properties might be more toxic in the form of nanoparticles due to the greater surface area.

The use of nanosilver has come under particular scrutiny, in part because it is needed in some areas — as a hospital disinfectant and in socks for diabetics, for instance. “But people develop a resistance to silver. If they come into too much contact with nanosilver, it’ll be ineffective in places where it’s needed,” Buening warned.

Despite signs of possible risks, there has been no scientific proof that certain nanoparticles are harmful in some way. So for consumers, many questions remain. Those seeking information on nanoproducts in order to weigh their pluses and minuses have a big problem because nanoproducts require no approval and do not even have to be marked as such.

“Consumers can look to see whether a product is expressly advertised as ‘nano’,” Buening said. “This is often the case with shoe-care sprays, for example.” And, secondly, when consumers, say, buy an enamel in a hardware store, they can ask to see the product data sheets. A reason to ask includes labelling with words like “antibacterial” or “dirt repelling”.

Product directions for use should always be read and followed. “For instance, sprays and especially aerosols should be used outdoors and at a sufficient distance,” Buening said. “They’ve got to be sprayed very finely, which makes them dangerous to the lungs.” And when they also contain nanoparticles, there is all the more reason to be careful. — Sapa-dpa.

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