DURHAM, N.C. The same properties of nanoparticles that make them so appealing to manufacturers may also have negative effects on the environment and human health.
However, little is known which particles may be harmful. Part of the problem is determining exactly what a nanoparticle is.
A new analysis by an international team of researchers from the Center for the Environmental Implications of NanoTechnology (CEINT), based at Duke University, argues for a new look at the way nanoparticles are selected when studying the potential impacts on human health and the environment. They have found that while many small particles are considered to be "nano," these materials often do not meet full definition of having special properties that make them different from conventional materials.
Under the prevailing definition, a particle is deemed nano if its diameter is between 1 and 100 nanometers (nm) about 1/10,000 the diameter of a human hair and if it has properties that significantly differ from its naturally occurring, or bulk, counterpart.
The special properties of nanoparticles come from their high surface-area-to-volume ratio. They also have a considerably higher percentage of atoms on their surface compared to bulk particles, which can make them more reactive. These man-made materials can be found in a vast array of consumer products, including paints and sunscreens, as well as in water treatment plants and drug delivery systems.
For most of this decade, discussions of nanoparticles have tended to focus more on their size than their properties. However, after reviewing the scientific literature, the Duke-led team believes that the old definition is not specific enough. A definition that focuses on properties is critical, they say, to help scientists determine which particular nanoparticles are the most likely to represent a threat to the environment or human health.
Generally speaking, it is the very small
|Contact: Richard Merritt|