Accordingly, the US' Environmental Protection Agency is under pressure to regulate commercial products containing silver nanoparticles. But it is not yet clear how precisely this 'knee jerk reaction', as it has been described, will be enforced.
In a "guilty-'til-proven-innocent" regulation by the EPA, any company marketing a product as containing silver nanoparticles to kill bacteria must provide scientific evidence that the particles pose no environmental health risk. A tricky one indeed. How can that really be "proved"? Methods for determining "nanotoxicology" are in only very early stages of development, mainly as it is difficult to know exactly what to look for. For example, there has been a study of carbon nanotubes (like short little straws made of carbon, a bit like a piece of graphite-sheet rolled back on itself) aimed to prove that they can generate free radicals. Accepting the Free Radical Theory of Disease (an extension of the Free Radical Theory of Ageing), if they were found to have produced radicals, that might be some evidence that we should fear them. However, there was no such evidence found, and moreover, it was concluded that the presence of carbon nanotubes actually diminished the yield of reactive oxygen radicals when present in systems known to generate them. However, we are quite some way from any conclusion than nanoparticles are actually good for you... although they may ultimately be so proven. Who knows? The jury is not so much as "out" as not yet elected.
The decision is the result of legal enmeshings concerning the 'Silver Wash' washing machine, marketed by Samsung as containing silver nanoparticles in order to kill bacteria in clothes. Some US water authorities are afraid that discharged nanosilver particles might concentrate in wastewater treatment plants, killing bacteria which were meant to detoxify the wastewater. That's a good point, in the sense that a broad-spectrum antibiotic can kill both the nasties and the good bugs in the digestive tract, with well known consequences, also ending up at a water treatment plant somewhere nearby. In this particular context, nanosilver could be listed among other environmental pesticides, and would accordingly need to be tested under the Federal insecticide, fungicide and rodenticide act (Fifra). So long as the silver nanoparticles were contained within the washing machine, it could be classified as a 'device', and this exempted it from Fifra. However, in taking the view that some of the particles could actually "escape", EPA have now reconsidered this decision. As EPA spokesperson Jennifer Wood put it: 'The release of silver ions in the washing machines is a pesticide, because it is a substance released into the laundry for the purpose of killing pests.' So there!
Although this particular washing machine uses silver ions, which may not constitute nanoparticles, silver nanoparticles are used to kill germs in such products as air-fresheners, shoe liners, socks and food-storage containers. In all probability, these products will all now have to be tested under the regulations. Silver nanoparticles are also added to bandages to speed healing; but these and other medical applications are regulated by the US' Food and Drug Administration, not the EPA. A legal loophole remains for companies who drop anti-microbial claims from their nanosilver products, since it is only products marketed as 'anti-microbial' that will have to be regulated.
Undoubtedly, the new regulation will justify more research into the toxic effects of nanoparticles, but who will pay for it? Will it be government funded e.g. through the Research Councils, or will the manufacturers and suppliers of these new technologies bear the burden? I think it most likely that industry will put some money into university labs., say by supporting a few Ph.D projects, which is a far cheaper option than doing in all in-house themselves at full-costs, and the universities are mostly (in the U.K. at least) sufficiently desperate for cash they will take whatever crumbs might thereby drop their way.