A Letter to the Editor published in the Journal of Food Science recently proposed a set of nine characterization parameters for studies on food and food-related nanomaterials.  The letter, from Jeffrey Card (Ashuren Health Sciences) and Bernadene Magnuson (Cantox Health Sciences International), cites the MinChar list as one of a number of sources.

From the letter:

We propose that a set of minimum parameters be determined and reported for nanomaterials that are used in experiments assessing various biological activities, including toxicity, regardless of the route of exposure that is being examined. This set includes the following 9 parameters:

• agglomeration and/or aggregation
• chemical composition
• crystal structure/crystallinity
• particle size/size distribution
• purity
• shape
• surface area
• surface charge
• surface chemistry (including composition and reactivity)

The letter can be accessed at JFS Vol 74, Number 8.

A recent editorial in the journal Nanotoxicology which addresses the dangers of indiscriminate generalizations on nanoparticle toxicity, has just been made freely available for a limited time.

In Nanoparticles – one word: A multiplicity of different hazards (Nanotoxicology Vol. 3, No. 4, Pages 263-264), 12 authors express their concern over “how the term “nanoparticles” is being somewhat indiscriminately used, especially in the titles of scientific papers and in statements to the press.”  They state:

No self-respecting researcher would dream of publishing results showing, for example, that quartz was a genotoxin under the title ‘Particles are genotoxic’. Generalizations like these are unhelpful and unscientific, and potentially dangerous in the wrong hands. Exactly the same applies for research into the toxicology and potential impacts of nanoparticles. Yet in 2009, papers are still appearing that explore the activity of a small range of nanoparticle types, yet uses the term ‘nanoparticle’ in its broadest sense in the title as though it was a generically useful term representing one class of hazard.

Responding in part to a recent paper that linked nanoparticles in the most general sense to seven very serious cases of occupational lung and pleural injury occurring in China (Song et al. 2009), the authors urge the author of papers to:

1. Ensure that all descriptions of nanoparticle hazards recognize the intrinsic heterogeneity of the nanoparticle hazard and discuss the uncertainty of alleged causality;
2. Ensure that there is a convincing and scientifically sustainable link between any nanoparticle exposure and any pathological outcomes putatively associated with that exposure; and
3. Ensure that sufficient physical and chemical characterization data are provided on the nanoparticles in question to support valid data interpretation and comparison.

The full paper van be accessed at http://dx.doi.org/10.3109/17435390903337701

The paper’s authors are (in alphabetical order):

Dr Rob Aitken, SAFENANO, Institute of Occupational Medicine, Edinburgh, UK

Professor Paul Borm, Hogeschool Zuyd, Heerlen, The Netherlands

Professor Ken Donaldson, University of Edinburgh, Edinburgh, UK

Professor Gaku Ichihara, Nagoya University, Nagoya, Japan

Professor Steffen Loft, University of Copenhagen, Copenhagen, Denmark

Professor Francelyne Marano, Université Paris Diderot-Paris 7, Paris, France

Dr Andrew Maynard, Woodrow Wilson Centre, Washington DC, USA

Professor Günter Oberdörster, University of Rochester, Rochester, NY, USA

Dr Herman Stamm, European Commission Joint Research Centre, Ispra, Italy

Professor Vicki Stone, Edinburgh Napier University, Edinburgh, UK

Dr Lang Tran, Institute of Occupational Medicine, Edinburgh, UK

Professor Hakan Wallin, National Research Centre for the Working Environment, Copenhagen, Denmark

On Tuesday November 17th, Travis Earles from the US Office of Science and Technology Policy (OSTP) emphasized strongly the Whitehouse’s support for developing and implementing good materials characterization practices in nanotoxicology studies.  Travis was speaking at the National Nanotechnology Initiative Human Health and Instrumentation Workshop.

The video of his presentation is available here, although you will need to register with the site to watch it (and currently it doesn’t seem to be viewable on a Mac).

I will try and post a transcript of the relevant sections of his presentation when it becomes available.

This week’s issue of C&E News has a great article on the MINChar initiative by Britt Erickson.

You can access the article here

(Note: the article is from Volume 86, Number 50, pp. 25-26 (Dec 15 2008).  C&E News is a publication of the American Chemical Society.  This link is provided with the permission of ACS, and does not infer any rights to the article.  For example, the article may not be linked to or otherwise distributed without express permission from ACS)

Just as a taster, two quotes from the article:

Clayton Teague, director of the National nanotechnology Coordination Office:

“There is a great need for improved characterization of the nanomaterials used in toxicity studies. Everyone recognizes that the materials used in many of the earlier studies were not adequately characterized, and some of the conclusions should not have been drawn,” says E. Clayton Teague, director of the National Nanotechnology Coordination Office, which coordinates federal nanotechnology R&D activities.

Kristen Kulinowski, director of ICON:

Kristen M. Kulinowski, director of the International Council on Nanotechnology at Rice University, agrees. “All of these allied efforts, each doing something a little bit different, will someday advance the quality of nanotechnology-risk-relevant research and help decision-making at the policy level,” she says.

Welcome to the Minimum Information for Nanomaterial Characterization Initiative.

This is a community initiative to improve the level of materials characterization in nanotoxicology studies.  It aims to complement other activities by encouraging the adoption of a minimum set of physical and chemical material characterization parameters in nanotoxicology studies.

Development of an organized approach to documenting critical characterization parameters is also seen as being of benefit to related activities such as nano-manufacturing and materials science.

The recommended parameters, developed at a workshop held in Washington DC between Oct 28-29 2008, can be found here.

These are designed to complement recommendations from other groups that include ISO and OECD.  And as they are a minimum set of parameters, it is anticipated that they will at some point be superseded.

But in the meantime, it is hoped that their widespread adoption and use within the nanotoxicology community will encourage a culture of more robust physical and chemical nanomaterial characterization, that enables better research interpretation and comparison.

As this is a community initiative, it stands or falls by the buy-in it receives from within the nanotechnology community.  You can become associated with the initiative by signing up on the Join The Community page.

Thank you.

Lead organizers:

Darrell Boverhof, The Dow Chemical Company
Shaun Clancy, Evonik Industries
Vicki Colvin, ICON
Ray David, BASF Corporation
Mark Hoover, NIOSH
Steve Klaine, Clemson University
Andrew Maynard, Woodrow Wilson International Center for Scholars
Nigel Walker, National Institute of Environmental Health Sciences (NIEHS)
David Warheit, DuPont

Workshop Summary

A workshop was held at the Woodrow Wilson Center in Washington DC between Oct 28 – 29 2008, with two aims:

• To develop minimal material characterization recommendations for nano-toxicology studies; and
• To develop a plan of action for encouraging adoption of these recommendations by researchers, research managers and research publishers.

This is a draft summary of workshop findings:

Purpose

• To develop minimal material characterization recommendations for nano-toxicology studies; and
• To develop a plan of action for encouraging adoption of these recommendations by researchers, research managers and research publishers.

Intended Outcomes

• Raise the bar for nanomaterial toxicology research, including
  • Facilitating/encouraging appropriate materials characterization in nano-toxicity studies
  • Fostering a culture of good nanomaterial characterization
• Enable effective use of research/increase relevance and impact of research
• Complement the work of other organizations, esp. ISO and OECD
• Encourage study designs that enable dose-response to be evaluated against alternative metrics
• Foster interdisciplinary collaborations

Anticipated Product

General guidance on nanomaterial characterization for the nanotoxicology research community (A tool that can be used by people funding, conducting, evaluating and using research)

Target Audiences

• Research Sponsors (Establishing guidelines for material characterization)
• Researchers (Generating data)
• Research evaluators (Providing a level of quality control on the dissemination of data through their existing professional and institutional responsibilities—and indirectly having an impact on study design)
• Research users (Decision-makers evaluating quality of data)

Recommended Minimum Physical and Chemical Characterization Parameters
What does the material look like?

• Particle size/size distribution
• Agglomeration state/Aggregation
• Shape

What is the material made of?

• Overall composition (including chemical composition and crystal structure)
• Surface Composition
• Purity (including levels of impurities)

What factors affect how a material interacts with its surroundings?

• Surface Area
• Surface Chemistry, including reactivity, hydrophobicity
• Surface Charge

Overarching considerations

• Stability—how do material properties change with time (dynamic stability), storage, handling, preparation, delivery etc?  Include solubility, and the rate of material release through dissolution.
• Context/Media—how do material properties change in different media; i.e. from the bulk material to dispersions to material in various biological matrices? (“as administered” characterization is considered to be particularly important)
• Where possible, materials should be characterized sufficiently to interpret the response to the amount of material against a range of potentially relevant dose metrics, including mass, surface-area and number concentration.

Notes

This framework is designed to stimulate appropriate characterization, while complimenting more specific guidance from organizations such as ISO and OECD.

Highlighting a key set of parameters without specifying prescriptive approaches to characterizing them is intentional, as an approach to fostering a culture of effective characterization without stifling innovation, developing a set of recommendations that are more likely to be considered by relevant communities, and allowing these recommendations to support the adoption of more authoritative guidelines from other sources. Furthermore, the intentional omission of defined methods is meant to foster discussions between researchers in the biological sciences and the materials sciences, both of whom play a role in characterizing the effects of nanomaterials on biological systems.

It was a shared view that inter-laboratory comparison studies, known to be desirable, are infrequent due to issues surrounding funding and accepted laboratory protocols.

Reference should be made to internationally recognized terms and definitions (e.g. ISO TC229), and to federally-funded institutions capable of providing characterization services.

Next Steps

• Consider establishing an independent web-based resource outlining the motivation, conclusions and recommendations of the workshop
• Develop a system to enable practitioners/stakeholders to sign up in support of the recommendations
• Publish a high profile article on the recommendations, and a path toward more appropriate nanomaterial characterization in toxicology studies