Yet according to a recent policy analysis paper submitted to the peer-reviewed Environmental Science and Technology journal by Swiss-based EMPA and Murray Height, Chief Technology Officer of HeiQ, nanosilver in the form of colloidal silver (suspended in liquid), has been widely used for more than 100 years and has been registered as a biocidal material in the USA since 1954, when the term ‘nano’ did not even exist. “Fifty-three percent of the EPA-registered biocidal silver products likely contain nanosilver,” according to the authors of the report.
The policy paper also points out that HeiQ is based on elemental silver, which is less soluble than some other silver treatments (ie silver chloride), and it also releases less silver ions in to the environment.
In addition, CEO Carlo Centonze told Ecotextile News that HeiQ AGS-20 was by definition not strictly a nanosilver product.
“HeiQ AGS-20 is a microcomposite with an average particle size distribution ranging between 1 and 3 micrometers but ranging up to 50 micrometers. The composite structure contains metallic silver with a particle size distribution from 0.001 to 1 micrometer and its main distribution by weight is clearly above the nanodefinition of 1 to 100 nanometers. So strictly scientifically speaking it is not a nanoparticle, (but) policy wise it has recently been categorised as containing a nanomaterial.
“When the first nanosilver was registered by EPA in 1954 the definition of nano did not exist, it was still called millimicron. Times change, definitions change, people change, policies change but materials sometimes just stay the same,” he concluded.
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