Silver Institute Executive Director Mike DiRienzo is quoted in a Mineweb article this week extolling the virtues of silver nano technology and explaining how the new applications for silver nano technologies will create a surge of demand for the metal. The basis of his enthusiasm is silver’s long acknowledged ability to disrupt the functioning of single cell bacteria now made dramatically more potent by its application on a nano scale. Nano technologies have many almost unique qualities such as invisible dispersion, targeted application and comparatively speaking, low cost. The USA is leading the world in developing new applications for nanosilver every day and clothes are already available that supposedly can be worn day after day without needing to be washed or kitchen appliances like refrigerators that are naturally sanitized. But some of the most exciting applications combine silver’s anti microbial qualities with its ability to act as a conductor, meaning it can be used in electric circuits embedded in the body. One application developed by Engineers at the University of California employs nanosilver wires embedded in a new contact lens that can measure changes in pressure across the cornea and via wireless can indicate the early stages of glaucoma, the world’s second leading cause of blindness.
What the article doesn’t do is explore the environmental concerns around the use of silver and how those concerns are proving a brake on more widespread adoption. The concerns can be highly technical in nature and for anyone keen on a more detailed analysis there is a Friends of the Earth report available running to eight pages. Broadly speaking though the problem seems to be that silver can be toxic to both good and bad bacteria; to quote the report, the potential for nanosilver to adversely affect beneficial bacteria in the environment, especially in soil and water, is of particular concern. Conversely, there is also a risk that use of nanosilver will lead to the development of antibiotic resistance among harmful bacteria. The industry, of course, vehemently refutes such suggestions and says the metals’ ability to reduce the risk of MRSA infections in hospitals (as just one example) vastly outweighs any potential risks. It’s probably the growth of silver use in disbursed situations that most bothers some scientists. One big growth area is in clothes where minute silver coated particles are fused with the garment fibers to kill bacteria causing personal hygiene problems. A well documented application is Samsung’s washing machine that releases 400 billion silver ion particles in every wash and thereby supposedly sanitizes the wash reducing the temperature and duration required. The worry is when these nanosilver particles are released into the environment will they kill beneficial bacteria required for soil nitrification and water purification? Will they accumulate like heavy metals to levels that become toxic to mammalian liver cells, stem cells and even brain cells?
Although it is entirely appropriate that such concerns are thoroughly researched, it is possible that such fears are over done. The photographic industry was using silver in vast quantities until this decade and the vast majority was simply flushed into the waste water system without any recorded ill effects. No doubt factory outflows were strictly controlled but millions of private developers operated unsupervised for a hundred years or more, using much higher concentrations.
The EPA has been evaluating nanosilver’s use as a microbial agent for some two years now and the industry is waiting a decision. Now if I could just find somewhere to buy silver impregnated socks ¦ ¦