24
May
Federal Researchers Eye Long-Term Nanosilver Toxicology Studies
(Beyond Pesticides, May 24, 2007) According to InsideEPA, the National Toxicology Program (NTP), part of the National Institute of Environmental Health Sciences (NIEHS), is likely to design and initiate a set of long-term studies on the toxicological properties of so-called nanosilver, a booming part of the nanomaterials commercial market about which little health data is available.
The nomination list includes a request from the Food & Drug Administration (FDA) to conduct a variety of studies on nanosilver and nanogold particles, including nanoscale materials characterization; metabolism and pharmacokinetic studies; acute, subacute and subchronic toxicity studies; and mechanistic studies to assess the role of size and surface coating on biological disposition and toxicity.
The term nanotechnology refers to research and technology that manipulates matter at the atomic, molecular, or macromolecular levels using a length scale of approximately one to one hundred nanometers in any dimension. A nanometer is one billionth of a meter, or around one ten-thousandth the diameter of a human hair. Nanotechnology allows certain materials to have different molecular organizations and properties because at their tiny size, they have far more surface area relative to their mass than their larger counterparts. Silver, for instance, has been known for years for its biocidal properties in its bulk form, as well as for its hazardous health effects. It is more efficient as nanoparticles.
Nanosilver is the first form of nanotechnology regulated by EPA. The U.S. Food and Drug Administration (FDA) also regulates nanoproducts, including pharmaceuticals, medical devices and biologicals. Products like food, cosmetics, food additives and food packaging also come under the purview of FDA. However, unlike pharmaceuticals and medical devices, FDA monitors the behavior of these products and takes regulatory action only if adverse events occur that “threaten public or individual health.” Nanomaterials are extremely common in cosmetics, and may pose a growing threat to public health, as their tiny size may allow them to be incorporated into the bloodstream and pass through cell membranes.
InsideEPA reports that NIEHS is currently leading a multi-agency research initiative looking at nanomaterials’ biological fate and transport, or how they move and break down in the body. NIEHS issued its request for proposals for the initiative last September. However, that project is assessing a list of nanomaterials that does not include nanosilver or nanogold particles because the list was developed before those substances became more commercially popular, sources say. The new NTP effort on nanosilver and nanogold, when results are available, will supplement the data generated by the interagency project, the sources add.
Nanogold is less common than nanosilver but is still in some commercial products, including certain kinds of toothpaste that claim the gold kills bacteria and in some dietary supplements that are likely to be of interest to FDA. Nanogold is also being tested as a cleaning agent for drinking water, but has not yet been formally approved.
The study process is expected to take several years.
Source: InsideEPA
