Dr. Andrew Maynard, director of the Risk Science Center at the University of Michigan, United States, in the journal Nature, argues that regulatory definitions of nanomaterials will do more harm than good. He was, previously, a proponent of a regulatory definition of engineered nanomaterials, but has since changed his mind – due to the danger of science being pushed aside as policy makers look for clear definitions on which to build “nano-regulatons”. Maynard writes, “A ‘one size fits all’ definition of nanomaterials will fail to capture what is important for addressing risk.” Other parameters, he says, beyond just size, like particle shape, porosity, surface area and chemistry, also modulate risk. “The transition from ‘conventional’ to ‘unconventional’ behaviour,” says Maynard, “when it does occur, depends critically on the particular material and the context.” A sensible definition is hard, if not impossible, to arrive at. What should be done instead, argues Maynard, is for regulators to work with a list of nine or ten attributes for which certain values trigger action, ensuring that other attributes beyond size and surface area are included. While such regulatory sophistication would require a lot of work, enough is known for an expert panel to begin determining such key attributes and the preliminary trigger points for many materials. The trigger points should also be flexible, so they can be modified as evidence grows. Maynard concludes: “assuming that nanomaterials are a unique class of material continues to present a stumbling block to effective regulation.”
http://www.nature.com/nature/journal/v475/n7354/full/475031a.html