Tag Archives: Health Canada’s Working Definition of Nanomaterial

Dr. Andrew Maynard discusses the Health Canada nanomaterial definition

1 Reply

I have often referred to and linked to Andrew Maynard’s writing on nanotechnology issues and am pleased to note he has kindly answered some questions about the Health Canada Working Definition of Nanomaterial. Before launching into his responses, here’s a little more about him.

Dr. Andrew Maynard was originally trained as a physicist and graduated with a PhD from Cambridge, UK  in 1993. He worked for a number of years for the UK Health and Safety Executive moving to the US to work with the National Institute of Occupational Health and Safety where he helped set up a nanotechnology safety programme post 2000 when the NNI was established. By 2005, he was employed at the Project on Emerging Nanotechnologies as their Chief Science Advisor. As of April 2010, he assumed responsibility as director of the Risk Science Center at the University of Michigan School of Public Health. He consults internationally on nanotechnology safety issues. He was a member of the expert panel consulted for the nanotechnology report, Small is Different; A Science Perspective on the Regulatory Challenges of Nanotechnology, published by the Council of Canadian Academies in 2008.

Since the 2008 report for the Council of Canadian Academies, Andrew has adopted a different approach to regulating nanotechnology, a change I first noted in an April 15, 2011 posting on the University of Michigan Risk Science Center blog. Excerpted from that posting,

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.

I waffle somewhat largely due to my respect for Andrew and his work and due to my belief that one needs to entertain new approaches for the emerging technologies, even when they make your brain hurt. (Before proceeding with Andrew’s comments and for anyone who’s interested in my take here is, My thoughts on the Health Canada nanomaterial definition.)

In any event, here are Andrew’s responses to my questions,

  • I have warm feelings towards this definition, especially the elaboration where I think they avoided the problem of including naturally occuring nanoparticles (as per your comment about micelles in milk); and they specify a size range without being doctrinaire about it. How do you feel about it, given that you’re not in favour of definitions?

The problem is that, while the Health Canada is a valiant attempt to craft a definition based on the current state of science, it is still based on a premise – that size within a well defined range is a robust indicator of novel risk – that is questionable.  Granted, they try to compensate for the limitations of this premise, but the result still smacks of trying to shoehorn the science into an assumption of what is important.

  • Do you see any pitfalls?

A large part of the problem here is an attempt to oversimplify a complex problem, without having a clear understanding of what the problem is in the first place.  Much of my current thinking – including questioning current approaches to developing definitions – revolves round trying to work out what the problem is before developing the solution.  But this makes commenting on the adequacy or inadequacy of definitions tricky, to say the least.

  • Is there anything you’d like to add?

My sincere apologies, I’ve just got to 5:00 PM on Sunday [Oct. 23, 2011] after working flat out all weekend, and am not sure I have the wherewithal to tackle this before collapsing in a heap.

I am hugely thankful that Dr. Maynard extended himself to answer my questions about the Health Canada definition of nanomaterial. To Andrew: a virtual bouquet of thanks made up of the most stunning flowers and scents you can imagine.

My thoughts on the Health Canada nanomaterial definition

2 Replies

In my Oct. 11, 2011 posting, I noted that Health Canada had released both its nanomaterial definition and its response to the public consultation that took place in 2010. Unfortunately, it’ s not possible to attempt the same sort of  analysis (mentioned in my Oct. 21, 2011 posting) that Dr. Andrew Maynard applied to the US government (National Nanotechnology Initiative) public consultation on EHS (environmental, health and safety) research strategy as Health Canada did not make the submissions available for viewing.

In my first posting, I focused largely on the public consultation aspects, now I’d like to look more closely at the definition itself (especially in the wake of the European Commission’s Oct. 19, 2011 announcement of its nanomaterials definition). Note: Health Canada says nanomaterial; European Commission says nanomaterials.

Here’s the definition (from the Policy Statement on Health Canada’s Working Definition for Nanomaterial webpage),

4.1 Health Canada’s Working Definition of Nanomaterial

Health Canada considers any manufactured substance or product and any component material, ingredient, device, or structure to be nanomaterial if:

  1. It is at or within the nanoscale in at least one external dimension, or has internal or surface structure at the nanoscale, or;
  2. It is smaller or larger than the nanoscale in all dimensions and exhibits one or more nanoscale properties/phenomena.

For the purposes of this definition:

  1. The term “nanoscale” means 1 to 100 nanometres, inclusive;
  2. The term “nanoscale properties/phenomena” means properties which are attributable to size and their effects; these properties are distinguishable from the chemical or physical properties of individual atoms, individual molecules and bulk material; and,
  3. The term “manufactured” includes engineering processes and the control of matter.

4.2 Elaboration

The Working Definition is not an additional source of authority, but works within the existing regulatory frameworks that allow for obtaining information.

Information is submitted to Health Canada regulatory programs as required by legislation and their associated regulations. Within these legislative and regulatory frameworks, Health Canada may request specific information (see Section 6) for a regulated substance or product that is, or contains, a nanomaterial as described in the Working Definition.

The term “manufactured” includes engineering processes and control of matter that lead to the synthesis, generation, fabrication or isolation of nanomaterials. Health Canada may request information regarding a deliberately or incidentally manufactured nanomaterial for risk assessment purposes. This term also includes natural components that have been deliberately used or engineered to have nanoscale properties/phenomena, used in nanoscale encapsulation of bioactive compounds, or used in tissue engineering.

“Part a” of the Working Definition relates to current evidence suggesting that nanoscale properties/phenomena are more likely observable at the scale of 1-100 nanometres (more often at the lower end) and “Part b” reflects that it is possible for nanoscale properties/ phenomena to be exhibited outside this size range, such as select quantum devices.

A variety of lexicons and interpretations of “nano-terminology” currently exist, underlining the importance of understanding the context in which these terms are used. In the risk assessment context supporting hazard and exposure assessment for risk characterization and management, the term “nanoscale properties/phenomena” refers to size-related properties which have qualities or characteristics that do not readily extrapolate from those observed in individual atoms, molecules or bulk materials. For example, “bulk” gold is not very reactive, but nanoscale gold can act as a chemical catalyst. For risk assessment purposes, this term includes observable biological or environmental effects resulting from size-related properties as described above. Examples of such biological or environmental effects could be increased permeability through cell membranes or increased reactivity of iron/iron oxides for the purposes of groundwater remediation, respectively.

Internal or surface structures at the nanoscale include nanomaterials that are aggregated or agglomerated to form a larger group. While the break-up of aggregates is less likely, a larger group could be broken down into component nanomaterials in the human body or the environment. Some regulatory programs may request information above the 100 nm size range to an upper limit of 1000 nm in order maintain flexibility to assess potential nanomaterials, including suspected nanoscale properties/phenomena. The 1000 nm cut-off attempts to separate characteristics attributable to macro-scaled materials from those of nanomaterials. However, a product or substance that contains nanomaterial could measure beyond 1 micron in size (for example (e.g.) bundles of carbon nanotubes that are very long). In these cases, regardless of the size, information may be requested for risk assessment purposes.

In addition to requesting information about nanomaterials, information regarding particles above the 100 nm size range may also be requested by some regulatory programs to assess possible biological effects that could be attributable to their dimension or size. These approaches may be applied on a case-by-case basis or to a whole product class.

While not expressly stated in the Working Definition, information regarding nanomaterial size distribution, especially number size distribution, is also relevant for risk assessment purposes.

Currently, there is insufficient evidence to establish common threshold values for size distributions of relevance across all substances and product lines that Health Canada regulates.

I find the fact that this is called a ‘working’ definition immediately establishes a very different frame of reference as the term ‘working’ in this context suggests flexibility. like a ‘working’ hypothesis which can by redefined as more information becomes available. You can find a longer definition for working hypothesis in this Wikipedia essay.

The first two items in the definition are very generalized (in fact, downright vague) but this changes when the meaning of the terms are described where everything becomes more specific. It’s only when reading the elaboration that one realizes how very carefully this definition has been constructed. They have given themselves a lot of ‘wiggle room’. For example,  “”Part a” of the Working Definition relates to current evidence suggesting that nanoscale properties/phenomena are more likely observable at the scale of 1-100 nanometres (more often at the lower end) and “Part b” reflects that it is possible for nanoscale properties/ phenomena to be exhibited outside this size range, such as select quantum devices.”  [emphasis mine]

I’m still waffling as to whether or not a definition is necessary although I’m inclined to say yes to a definition when I see something like this. I think a good balance has been struck between caution and unnecessary (at this time) regulation. E.g., ” Currently, there is insufficient evidence to establish common threshold values for size distributions of relevance across all substances and product lines that Health Canada regulates.” [emphasis mine]