On January 10, 2011, Environmental Science & Technology posted a peer-reviewed pre-publication article entitled “120 Years of Nanosilver History:  Implications for Policy Makers,” which shows that nanosilver in the form of colloidal silver has been used for more than 100 years and, according to the authors, has been registered as a biocidal material in the U.S. since 1954.  The article states that 53 percent of the U.S. Environmental Protection Agency (EPA)-registered biocidal silver products likely contain nanosilver and most of the applications are silver-impregnated water filters, algicides, and antimicrobial additives that do not claim to contain nanoparticles.  The authors state: “The implications of this analysis for policy of nanosilver is that it would be a mistake for regulators to ignore the accumulated knowledge of our scientific and regulatory heritage in a bid to declare nanosilver materials as new chemicals, with unknown properties and automatically harmful simply on the basis of a change in nomenclature to the term ‘nano.’”