Physics News

A nanoparticle growing in popularity as a bactericidal agent has been shown to be toxic to fish, according to a Purdue Univ. study. Tested on fathead minnows--an organism often used to test the effects of toxicity on aquatic life--nanosilver suspended in solution proved toxic and even lethal to the minnows.

"Silver nitrate is a lot more toxic than nanosilver, but when nanosilver was sonicated, or suspended, its toxicity increased tenfold," said Maria Sepulveda, an assistant professor of forestry and natural resources whose findings were published in the journal Ecotoxicology. "There is reason to be concerned."
"These nanosilver particles are so small they are able to cross the egg membranes and move into the fish embryos in less than a day," Sepulveda said. "They had a potentially high dose of silver in them."
"Silver has been used in the past as an antimicrobial agent. It's a known toxicant to microorganisms," he said. "Nanosilver is being considered by the EPA for environmental exposure profiling, much like a pesticide."
"The use of nanosilver could provide a number of sanitary benefits if used properly," Turco said. "However, the indiscriminate inclusion of nanosilver into products to simply allow them to say they are antimicrobial is creating a cautionary issue."