Nanosilver

Nanosilver is omnipresent: sports socks, refrigerators, cosmetics – in TV and print media, on the Internet, and especially in product advertising the noble silver is increasingly talked about, with the claims that it protects against unpleasant odors and bacteria, and makes skin creams more durable than ever. The fact is that silver ions do indeed have an antibacterial effect. In particular, they are able to penetrate cell membranes and damage the metabolism of microorganisms.

Silver ions in medicine is nothing new in itself: silver preparations were already being used in the 19th century to fight infection. When better and cheaper methods of combating infection became available after the Second World War, the importance of silver in the medical field diminished.

The disinfecting effect of silver is greater the larger the surface of the silver particles used. Nanosilver is where particles are smaller than 100 nm (one nanometer is one millionth of a millimeter or 10-⁹ meter). And it’s all about these tiny little particles, because larger surface area nanosize materials often have properties that differ from the same materials with a smaller surface area. With modern technical processes, nanoparticles are becoming easier and cheaper to produce. However, the impact on the environment and human health is difficult to gauge.

Silver ions are poisonous to fish and other aquatic creatures, apparently to a much greater extent than previously thought. This is because the large surfaces of the smallest particles increase not only the effectiveness against unwanted germs, but also the repercussions in the environment. Silver cannot go back into a recycling sequence, as it combines chemically with its environment, and thus cannot be removed from the water again. In addition, there is some controversy as to whether the use of silver ions promotes allergies in the home.

The Berlin-based Federal Institute for Risk Assessment finds the excessive use of silver problematic for other reasons: the health risks of permanent contact with silver ions are not conclusively known, indeed some forms of bacterial resistance have already been observed. Therefore, the use of nanosilver should be restricted to applications where it is indispensable.

What about those silver socks in the supermarket? Are they absolutely necessary? Or was the silver industry looking for new uses after the requirement for silver in analogue photography disappeared?

Sources:
[1] Federal Office for the Environment. Synthetic Nanomaterials Action Plan: Federal Council second report on the state of implementation, its impact and the need for regulation. Bern: 2014. Available at www.bafu.admin.ch
[2] Federal Institute for Risk Assessment. The BfR advises against nano-silver in foods and everyday products. Report No. 024/2010 of 28 December 2009.