Silver has antimicrobial properties, and a number of common items incorporate silver nanoparticles to take advantage of this attribute. For example, the plastic handle on the paper towel dispenser in my laboratory says it contains silver nanoparticles “to help prevent the spread of disease.” Another major application is in clothing. In this case, manufacturers impregnate the clothing with silver nanoparticles to help prevent odors caused by the presence of bacteria.

Savvy environmentally conscious shoppers may infer that clothing containing silver nanoparticles will have a larger environmental impact than traditional clothing because mining and refining the silver and making nanoparticles all contribute additional environmental impacts. However, the nanosilver clothing presumably needs to be laundered less often because it doesn’t smell as readily, and therefore the environmental impacts associated with washing the clothing will be smaller. But, can less frequent laundering really offset the additional environmental impacts of using the silver nanoparticles?

A recent study addressed this very question by comparing the life cycle assessments (LCAs) of both cotton and polyester shirts containing nanosilver to that of their untreated counterparts. Whether or not reducing the number of washings can make up for the additional environmental impacts of the nanosilver depends on the environmental impact category. For the categories of global warming potential, smog formation, acidification, and respiratory effects, the LCA results showed that reducing the number of washings by 30-50 percent would offset the additional impacts of incorporating silver. But, for the categories of ecotoxicity and carcinogenics, the LCAs revealed that it probably is not possible to offset the additional environmental impacts because the number of washings must be reduced by a whopping 90-100 percent.

Complicating the interpretation of these LCA results is the fact that no study has ever shown that consumers actually launder nanosilver clothing less frequently than traditional clothing. Without a change in consumer behavior, it seems clear that nanosilver impregnated clothing is not a greener choice than conventional clothing.

Source: Hicks AL et al. “Life Cycle Payback Estimates of Nanosilver Enabled Textiles under Different Silver Loading, Release, and Laundering Scenarios Informed by Literature Review.” Environmental Science and Technology. 2015.

David Tyler is the Charles J. and M. Monteith Jacobs Professor of Chemistry at the University of Oregon.

Image: Chiot’s Run via Flickr