Canadian Fish Are Ingesting Nanosilver

The antimicrobial additive isn't good for wildlife.

view of an Ontario lake
View of an Ontario lake.

K Martinko

Interest in nanotechnology has surged in recent years. Tiny particles with antimicrobial properties are being added to a range of consumer products, from socks, bedsheets, athletic gear, and condoms, to cooking pots, hair straighteners, and stuffed animals in order to inhibit bacterial growth and control odor. 

While the idea is interesting and scientifically sound, some researchers are concerned about what happens when these nanoparticles migrate into the natural environment, either during use or when a product is discarded at the end of its life. The antimicrobial properties may not be so helpful when disseminating throughout a natural ecosystem.

In order to better understand this, researchers from the Institute for Watershed Science at Trent University have been conducting a lengthy, ongoing study on nanosilver, one of the most commonly used nanoparticles, at the Experimental Lakes Area in Northern Ontario, Canada. 

In 2014 and 2015 nanosilver was added to a small enclosed lake that has no other human inputs. It's a "living laboratory," a rare location where research can be conducted right at the ecosystem level without having to control for external influences. The Globe and Mail reports,

"In total, 15 kilograms [33 pounds] of finely milled silver were used by the experiment, and suspended in a diluted solution that researchers repeatedly carried through the bush in 80-pound backpacks to pump into the 16-hectare lake used for the study."

The researchers found that, even though the amount of nanosilver in the lake measured in the parts-per-billion, the quantities appearing in fish taken out of the lake were 1,000 times higher. This reveals that the nanosilver does not just settle at the bottom of the lake and that it can enter the food chain and affect entire fish populations.

Yellow perch were found to have accumulated the tiny silver particles in their gills. From The Globe and Mail: "The fish were then shown to experience a chemical imbalance in their cells know as oxidative stress, which made them more lethargic and less able to feed. Their populations also shrank and shifted to deeper waters." The perch's predator, Northern pike, also revealed silver accumulations that persisted for four years after the experiment's conclusion.

Despite this, the study concludes that nanosilver is no different from silver in its natural form; thus, it "does not need to be regulated as a separate material but should instead be considered as part of the total silver load on a freshwater ecosystem." The fact that it does harm fish, however, cannot be ignored.

These latest findings build on research previously conducted by the same team in the Experimental Lakes Area that found nanosilver changed the mix of bacteria and algae on the lake bottom. It compromised the bacteria's ability to cycle nutrients such as carbon, nitrogen, and phosphorous, which is a crucial part of an aquatic ecosystem and plays an important role in recycling dead organisms.

Fisheries biologist Lauren Hayhurst, who participated in the research, does want consumers to realize that nanosilver-infused products are, most of the time, unnecessary. (Some exceptions could be medical bandages and skin gels used to treat burns.) They add a burden to the natural environment that could be avoided by buying non-nano products and by taking other, more commonsense precautions, such as washing one's athletic gear when it starts to smell (or even before). 

The study will be published this month in the Archives of Environmental Contamination and Toxicology. The following video, released by Trent University, explains more about the Experimental Lakes Area research.