A new concern about Nanotechnologies safety has been raised in a paper to be published by US and French Scientists. The concern is that the word ‘nanoparticle’ applies typically to anything that is smaller than 100nm. It is argued that this definition is not rigorous enough and that for health reasons the nanoparticles should have clearer definitions.
The review paper to be published in Nature Nanotechnology argues that due to the diverse uses of nanoparticles it would be best to propose a more categorized system of defining different nanoparticles to do with their attributes rather then their size.
Researcher Mark Weisner of Duke University states that there are distinct differences in the physiochemical characteristics of different nanoparticles. For this reason it would be incorrect to ‘tar all nanoparticles with the same brush’. As, for example, certain nanoparticles have size-dependent changes in crystal structure, which can influence their reactivity. this is important for ascertaining how they interact with the environment and what risk if any they may pose.
The study highlights a distinct group of nanoparticles that Weisner believes would cause the most trouble and those are the ones below 30nm in size. So Weisner proposes a 30nm limit to nanoparticle size. This has caused responses from two key figures. A response from Ken Donaldson of the Safety of Nanomaterials research Centre in Edinburgh. He states that there is no proven consequences of a size related change in properties. He also states that there seems to be no rational behind restricting the definition of nanoparticles to those below 30nm. He also believes that any such restriction would be premature and have no toxicological proof.
Weisner argues that his 30nm limit would only be a guide. He believes that the categorization due to novel properties may be a better approach with greater relevance.
What is certain about this paper is that it has started a debate about how nanoparticles should be categorized. Debate is always a great way to advance proceedings and has got the ball rolling on this key issue. – CT