In experiments reproducing the natural environment, Duke University researchers have demonstrated that silver nanoparticles, which are used in many consumer products, can have an adverse effect on plants and microorganisms.
These preliminary findings are important, the researchers said, because little is known about the environmental effects of these nanoparticles, and the only studies conducted to date involve high concentrations of the nanoparticles in a laboratory setting, which they point out, doesn’t represent “real-world” conditions.
Silver nanoparticles are used in a host of products, most commonly in textiles and clothing. These nanoparticles are used because one of their characteristics is the ability to kill bacteria, inhibiting unwanted odors. They work through different mechanisms, including generating oxygen free radicals which can cause DNA damage to microbial membranes without harming human cells. Other products with silver nanoparticles are children’s toys and pacifiers, disinfectants and toothpaste.
The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.
For their studies, the CEINT researchers created mesocosms, which are small, man-made structures containing different plants and microorganisms meant to represent the environment. They applied biosolids with low doses of silver nanoparticles in the mesocosms, then compared the effects of the nanoparticle-treated plants and microorganisms to the mesocosms receiving no nanoparticles.
“Our results show that silver nanoparticles in the biosolids added at concentrations that would be expected to a diverse terrestrial ecosystem caused ecosystem-level impacts,” the researcher said. “Specifically, the nanoparticles led to an increase in nitrous oxide fluxes, changes in microbial community composition, biomass, and extracellular enzyme activity, as well as species-specific effects on the above ground vegetation.”
The researchers plan to continue their studies with another ubiquitous nanoparticle – titanium dioxide. Also, while the latest study of silver nanoparticles lasted 50 days, the researchers plan to study the long-term effects of such exposures.
This story is reprinted from material from Duke, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.