Nanosilver: Weighing the Risks and Benefits

Abstract

It takes a special sort of case to spur attorneys into a debate over the drooling habits of toddlers. Yet that’s where lawyers from the Natural Resources Defense Council (NRDC), the U.S. Environmental Protection Agency (EPA), and Swiss chemicals company HeiQ found themselves in January 2013 as they debated in a federal appeals court the extent to which 1-year-olds and 3-year-olds chew, salivate, and swallow.1 At issue in the NRDC’s suit against the EPA, which is still awaiting ruling, was whether the agency was right in granting a conditional registration in December 2011 to a nanosilver-based antimicrobial fabric treatment manufactured by HeiQ.2 The EPA’s risk assessment was based in part on assumptions about exposure of 3-year-olds by sucking or chewing on nanosilver-laced textiles such as clothing, blankets, and pillowcases. Silver nanoparticles are added to a variety of textiles and home goods as an antimicrobial. Although silver has been used safely for centuries, some question whether the rapid expansion of new exposure sources to nanosilver could have adverse consequences. ... NRDC lawyer Catherine Rahm, however, begged to differ with the agency’s methods. In the January hearing, she argued that the agency record shows infants are more likely than any other subset of children to chew on fabrics that could contain the pesticide, and that if the agency were to recalculate its risk assessment based on the body weight of a 1-year-old, nanosilver concentrations in HeiQ’s product could result in potentially harmful exposures. It’s an obscure but critical distinction as far as risk assessment goes. And given the implications for HeiQ and other companies looking to follow in its footsteps, the case has landed at the center of a prolonged conflict over the regulation of nanosilver and the growing deployment of this antimicrobial ingredient in a variety of commercial and consumer products. Yet regardless of which side prevails in the case, the truth about nanosilver is not black and white. Even the loudest voices joining the NRDC’s call for strict regulation of nanosilver concede that context is key. “I’m not somebody who is for or against nano,” says Ian Illuminato, who directs Friends of the Earth’s U.S. nanotechnology campaign, which has produced a series of reports on the potential dangers of nanosilver and other nanomaterials. “I’m just saying we need to do this in a mature and adult way. That’s not to say this isn’t a helpful technology and it doesn’t have a place in our future, but in the way it’s evolving right now, it’s very risky.” Greg Lowry, a researcher at Carnegie Mellon University who studies the fate of nanoparticles in the environment, agrees that the use of nanosilver is a matter of balancing risk and reward. “There’s a tremendous potential benefit to the use in some of these products,” he says. “What one has to do is to ask yourself whether the benefits outweigh the risk.”