Cross-posted from The Risk Science Blog:

In a recent letter to the journal Nature (Nature 476; 399), Hermann Stamm of the European Commission Joint Research Centre Institute for Health and Consumer Protection (JRC-IHCP) defended the need to define engineered nanomaterials for regulatory purposes. The letter, titled “Nanomaterials should be defined”, was a direct response to my earlier commentary in Nature “Don’t define nanomaterials”.

Stamm’s letter is behind a paywall and so not easily accessible to many readers. But these are the main points he makes:

• A definition for engineered nanomaterials is required for labeling purposes, and would assist industry and regulators in identifying where specific safety assessments might be necessary.
• This should identify a general class of materials for attention, whether they are benign or hazardous.
• Nanomaterials have many properties not shared by their larger-scale counterparts, some of which have safety implications. And an increasing number of products containing novel nanomaterials are entering the market.
• Engineered nanomaterials are heterogeneous. But, they all have structures on the nanoscale which modify their other properties. Because of this, size is therefore most appropriate parameter to base a regulatory definition on.

Stamm also references a Joint Research Center Reference Report on “Considerations on a Definition of Nanomaterial for Regulatory Purposes”, co-authored by him and published in 2010.

As is probably clear from my Nature commentary (an early draft is freely available here), I have some sympathies with the challenges the JRC and regulators across the world are facing. Without a doubt, sophisticated materials arising from nanoscale science and engineering are presenting safety challenges that are not readily captured by current regulatory regimes. Yet I am increasingly concerned that, with the momentum that has built up behind the field of nanotechnology, it is becoming increasingly difficult to formulate evidence-based questions that will lead to science-justified regulation. And despite policy makers repeatedly stating that any form of nanomaterial regulation should be science-based, I have the sense that they are scrambling to use science to justify a predetermined conclusion – that engineered nanomaterials should be regulated on the basis of a hard and fast definition – rather than using science to guide their actions.

Instead, I would suggest that we need to put aside preconceptions of what is important and what is not here, and start by asking how new generations of sophisticated (or advanced) materials interact with biological systems; where these interactions have the potential to cause harm in ways not captured within current regulatory frameworks; and how these frameworks can be adapted or altered to ensure that an increasing number of unusual substances are developed and used as safely as possible – no matter what label or “brand” is applied to them.