Nanoparticles - do they pose a health risk?

By Eva Neumann Feb 20, 2012, 3:06 GMT

Berlin - The fruit in the air-tight container looks freshly picked for days, and the negligee, as well as the building facade, are guaranteed to stay free of microorganisms. Nanotechnology, now spreading to 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 nanometers 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, for example, 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 often 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. They may also get inside cells.'

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 really needed,' Buening warned.

Despite signs of possible risks, there has been no scientific proof to date 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.

'For one thing, 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 or a coating 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.'