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Posted: Apr 15, 2011

Why we don't need a regulatory definition for nanomaterials

(Nanowerk Spotlight) Engineered nanomaterials present regulators with a conundrum there is a gut feeling that these materials present a new regulatory challenge, yet the nature and resolution of this challenge remains elusive. But as the debate over the regulation of nanomaterials continues, there are worrying signs that discussions are being driven less by the science of how these materials might cause harm, and more by the politics of confusion and uncertainty.
The genesis of the current dilemma is entirely understandable. Engineered nanomaterials are typically the product of nanotechnology a technology that has been lauded as leading to designed materials with unique physical and chemical properties. Intuitively it makes sense that these unique properties could lead to unique risks. And indeed a rapidly growing body of research is indicating that many nanoscale materials behave differently to their non-nanoscale counterparts in biological environments. Logically, it seems to follow that engineered nanomaterials potentially present risks that depend on their scale, and should be regulated appropriately.
Yet the more we learn about how materials interact with biology, the less clear it becomes where the boundaries of this class of materials called "nanomaterials" lie, or even whether this is a legitimate class of material at all from a regulatory perspective.
In an evidence-driven society, now would be the time to take stock to ask what the science tells us about risks associated with exposure to materials more generally, and to reformulate the problems we are trying to address when it comes to nanomaterials. But increasingly, evidence is taking a backstage role in the process of developing definitions for regulatory purposes. This was highlighted recently by Henrik Laursen, coordinator of the nano team in the European Commission's environment department, who was reported on as stating that ultimately, the decision on a regulatory definition of nanomaterials would be a policy decision.
This should ring alarm bells throughout the scientific community. The statement implies that the basis for determining whether a material or product is regulated as a nanomaterial will be a term of art, not of science. In other words, a producer of a nanomaterial will not be able to assume that the product will be regulated on the basis of evidence pertaining to the harm it might potentially cause. Or a consumer of nanomaterials will have no assurance that the safety of a material is based on science, rather than political expedience.
This situation has been exacerbated by the underlying assumption that nanomaterials present a unique risk. And all too often the science has been co-opted to support this position rather than to evaluate it. For instance, in December 2010, the European Commission Directorate General for Health and Consumers Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) published an extensive evaluation of the scientific basis for the definition of the term "nanomaterial". The immutable basis for the evaluation was that "there is an urgent need to identify what can be considered as a nanomaterial by clear unequivocal descriptions."
Reading the resulting document, there is a palpable sense of the authors contorting themselves to serve an assumption that doesn't align well with the facts. It's no surprise therefore that the conclusions they reach are peppered with caveats that seem to call into question the assumption on which their task was based. Yet at the end of the day, they acquiesce to the task in hand and make a series of recommendations to support a working definition of nanomaterials that are only tenuously based on evidence.
And this is perhaps the crux of the challenge now being faced: No-one it seems is prepared to challenge the base-assumption that a regulatory definition of nanomaterials is needed.
Five years ago, the state of the science was such that it still seemed feasible that a regulatory definition of nanomaterials could be crafted. Today, that hope is looking increasingly tenuous. We know that size matters when it comes to understanding the risks presented by materials generally and particles more specifically and that characteristics such as physical form and chemistry are also important. But these are relevant from diameters of tens of micrometers where particles begin to be able to penetrate organisms down to the nanometer size range. At different length scales, different material-biology interactions lead to different mechanisms of action that have the potential to cause harm in different ways. But there are no rules that are generalizeable to the nanoscale specifically that much the science is clear on. And this alone calls into question the scientific-basis of enforcing nanoscale-specific regulations.
Rather, the science suggests that we have a bigger task in hand how do we develop a better understanding of how any particle capable of entering or otherwise interacting with an organism might cause harm, and how do we codify this in evidence-based guidelines that will inform regulation?
As an increasing array of sophisticated materials are developed and used many depending on complex arrangements of components to determine their functionality; some exhibiting properties that can be switched on or off, or even modified, depending on their environment clear science-based guidelines are needed on how to ensure these materials are adequately regulated. This requires moving away from concrete definitions on classes of materials that have no direct relevance to risk, and toward rules that determine whether a new material constitutes a new regulatory challenge, and how that challenge may be most appropriately addressed.
Martin Philbert, David Warheit and I recently proposed three principles for identifying new materials in a review paper on nanotoxicology "The New Toxicology of Sophisticated Materials: Nanotoxicology and Beyond", that potentially present new risk-based challenges: emergent risk, plausibility and impact. These are designed to identify new materials that require further research before their potential risks are understood and can be adequately addressed. But they could equally form the basis of developing new approaches to material regulation.
Ironically, many sophisticated materials that will emerge over the next few years will incorporate nanoscale structures. And yet, a non evidence-based regulatory definition of nanomaterials could end up causing more harm than good, as science-insensitive criteria create confusion amongst producers and users alike. Difficult as it may be given the momentum of current efforts to define nanomaterials for regulatory purposes, now is the time to shift toward evidence-based regulation of sophisticated materials.
This is not a call to ease restrictions on the use of new materials or to subvert attempts to inform consumers of nanomaterial-containing products. Rather, it is a necessary step toward ensuring the safety of new products by supporting regulations that are grounded in science. As the SCENIHR committee concluded in its 2010 report,
"'nanomaterial' neither implies a specific risk, nor does it necessarily mean that this material actually has new hazard properties compared to its constituent parts or larger sized counterparts."
Instead of trying to make the science fit the assumptions, we need to ensure the assumptions adapt to the science then we might be in a better position to use the best available scientific evidence to make informed decisions that protect health, while incentivize the production of safe and effective materials.
Five years ago, I was a strong proponent of developing a regulatory definition of nanomaterials. Today, with the knowledge we now have, I think we need to start thinking more innovatively about how we identify new materials that slip through the regulatory net whatever we decide to call them. Only then will we have a hope of developing science-grounded regulation that protects people while supporting sustainable development.
By Andrew Maynard. Andrew is Director, University of Michigan Risk Science Center and Professor, Environmental Health Sciences.

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