additives feature | Antimicrobials and biocides
explains. Safety studies were conducted by the Organi- sation for Economic Co-operation and Development’s (OECD’s) Working Party on Manufactured Nanomateri- als (WPMN), which uses Agpure as a reference material, notes Schneider. Ras Materials expects to receive EU approval under the Biocidal Products Regulation based on the OECD WPMN test results. In the US, the same regulatory rules apply to
Medical devices are just one market for Americhem’s nShield silver and organic antimicrobials
durable, broad-spectrum antimicrobial protection against bacteria, mould, mildew and algae, and is a cost-effective alternative to silver-based additives, says Dave Helmer, director of sales and marketing at Janssen PMP. Sanafor has no impact on mechanical properties, provides good thermal stability, and has low water solubility, which limits migration from the plastic.
Nanosilver developments Most silver-based products in plastics use ionic silver released from a carrier, such as a zeolite, through an ion-exchange process. Nanosilver, on the other hand, is a nano-sized undissolved silver metal particle. Agpure from Ras Materials, for example, is pure silver incorporated into the polymer where it releases silver ions by diffusion rather than ion exchange, explains Gregor Schneider, head of business development at the company. Ras Materials supplies masterbatches in a range of polymers. Schneider says the additive is expected to be used increasingly in healthcare and in food packaging and food related areas. As with other ‘nano’ materials that venture into new and uncharted territory, nanosilver has received both positive attention for its potential benefits and negative attention because some fear that its risks are unknown. Risks were unknown 10 years ago, but extensive studies since then have shown that nanosilver incorporated into plastics does not pose any risk to humans, workers, or the environment, when used according to regulations, says Schneider. “Nanosilver particles are not stable without a
protecting matrix, so airborne particles do not occur. No silver nanoparticle can be released by abrasion or dilution; only silver ions are released in water,” he
42 COMPOUNDING WORLD | July 2015
nanosilver as any other biocide. “EPA’s policy regarding nano-pesticides and inerts, albeit proposed, is clear: EPA applies an initial presumption that nanoscale versions of previously-registered active or inert ingredients in pesticide products are considered new ingredients subject to Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) registration,” explains Lynn Bergeson, managing partner at Bergeson & Campbell, a Washington, DC law firm focusing on such markets. “EPA also currently takes the position that each unregistered source of nanosilver is a new active ingredient and different than other currently registered sources of nanosilver. EPA has stated that, over time, it may develop the experience and establish a record that would allow EPA to conclude that different sources of nanosilver with the same particle size and charge are the same active ingredient.” EPA had previously issued one FIFRA registration for
nanosilver, to HeiQ for an antimicrobial fabric treatment, and this May issued a registration a nanosilver-contain- ing antimicrobial pesticide product named NSPW-L30SS to Nanosilva. According to an EPA announcement, “This silver-based product will be used as a non-food-contact preservative to protect plastics and textiles from odour- and stain-causing bacteria, fungi, mould and mildew. Items to be treated include, for example, household items, electronics, sports gear, hospital equipment, bathroom fixtures and accessories.” After evaluating the available data, EPA said, “These
data show that plastics and textiles treated with NSPW-L30SS release exceedingly small amounts of silver. Based on this evaluation, the Agency determined that NSPW-L30SS will not cause unreasonable adverse effects on people, including children, or the environ- ment and that it would be beneficial because it will introduce less silver into the environment than compet- ing products. EPA is also requiring the company to generate additional data to refine the Agency’s exposure estimates.” In the US, companies that wish to use or market
nanosilver in plastics should seek advice from EPA’s Office of Pesticide Programs (OPP) or seek legal counsel, advises Bergeson. “Marketers of such products are subject to intense scrutiny. Federal regulators are interested in compliance with FIFRA,
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