An industry group, the Silver Nanotechnology Working Group, said that there has been a long history of safe, regulated use of ionic silver, which “suggests that the EPA is adequately managing the risks of silver nanoparticles.”
Ionic silver has been used over the last six decades for a variety of anti-microbial uses, including algaecides, water filters and disinfectants approved by the EPA. The industry group says there is no difference between it and the newer nanosilver – other than the new name – so there are “no significant new risks.”
But Todd Kuiken, a research associate at the Project on Emerging Nanotechnologies, said that unlike ionic silver, the particles used in consumer products are “intentionally engineered at the nanoscale for its properties” and that they may react differently with whatever they come in contact with. “There are a few studies out there that show that nanosilver reacts differently than conventional ionic or colloidal silver,” he said.
Dale Kemery, an EPA spokesman, said that the field of nanotechnology is “relatively new and the scientific information on the potential environmental and human health risks is limited.”
As a result, he said the EPA is consulting with a panel of scientists to figure out how to assess the potential risks. In September, the agency announced a research strategy to identify what happens to nanomaterials used in products such as sunscreens, paints, automobiles and electronics and how to avoid potential health or ecological problems.
Eric Hoek, a UCLA professor of environmental engineering and a member of the University of California Center for Environmental Implications of Nanotechnology, said the prevailing wisdom is that silver isn’t toxic to humans. But he added that there hasn’t been much human exposure to silver nanoparticles until recent years, when use of them has increased. They are now used in 259 products on the market today, according to the Project for Emerging Nanotechnologies.
“These materials have tremendous potential, but we need to proceed with cautious optimism,” Hoek said. “We need people to be skeptics, but not to be unjustly fearful and inciting fear unnecessarily.”
Mark Wiesner, director of the Center for the Environmental Implications of Nanotechnology at Duke University, is researching the effects that nanomaterials have on ecosystems rather than individual animals. His center is constructing 30 different aquatic mesocosms – experimental, miniature ecosystems – where small amounts of nanoparticles will be released.
“We’re looking at things that you wouldn’t be able to predict if you look from a molecular to organization level,” Wiesner said. “For example, if you take DDT and you predict its effects from organism to organism, you never would have guessed it would bioaccumulate. There are ecosystem-level effects that only become apparent when you look at the compete system.”
Hoek explained that silver particles are dynamic in the environment so they “are going to take different forms, react and form new particles.”
“To be able to say conclusively that they are good or bad is wrong from the beginning,” he said.
There are still many questions that need to be answered about toxicity of silver nanoparticles, said Kuiken at the Project on Emerging Nanotechnologies.
“The products are already out there, but we’re still waiting to see if they are really safe,” he said.
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.