Temptation, Temptation, Temptation: Why Easy Answers About Nanomaterial Risk are Probably Wrong

These are just some of the frames applied by the mainstream media to research publications released in the last year or so. Whilst many celebrate the amazing properties these novel materials can bring to technological applications, others fear we may be opening a modern Pandora's box. When the Center for Biological and Environmental Nanotechnology (CBEN) at Rice University was funded in 2001, there was almost no scientific literature on the potential environmental, health and safety risks (EHS) of engineered nanoparticles.

CBEN began some of the earliest focused research to explore these issues even as its scientists pursued the "sunny side" of nano-enabled medical therapies and water treatment. Journalists quickly realized that nano-risks might be newsworthy and started posting stories whenever a new paper linking nanoparticles and unwanted outcomes came out.

Temptation #1: Generalizing Results from One Study to All of "Nanotechnology"

It is tempting-but irresponsible-to draw general conclusions about nanoparticle risks from a single paper. Science rarely works that way, especially in young and emerging fields where research practice has not been sufficiently standardized and old methods need to be validated for use with new materials. Moreover, the diversity of objects, devices and nanoparticle types that can be included under the umbrella term "nanotechnology" defies easy answers. A better approach is to look at the whole corpus and try to tease out some general themes that can guide future research.

As late as 2005, the limited number of extant papers were scattered in diverse journals, making the results difficult to find, much less compare or collate into a cohesive message for journalists, policymakers and risk managers. The group that I direct, the International Council on Nanotechnology, set out to make it easier to find these needles in the nano-haystack.

Our first project was the creation of the Virtual Journal of NanoEHS, the world's first comprehensive database of research publications addressing this aspect of nanotechnology. The papers are indexed according to particle type, exposure route and other factors and catalogued with full bibliographic information and a link to the journal's website. We've added an analytical tool that allows one to track trends in the field and print out customized reports well as a commenting and rating function to provide a forum for community discussion of the research.

Temptation #2: Mischaracterizing the Impacts Research as Either Non-Existent or Conclusive

What can we learn from this body of work? First, there's a lot more data now than there was back in the early days. Between 2001 and 2008 (the last year for which complete data are available), the annual NanoEHS publication rate grew between 20-120% per year. With over 3600 individual papers in the VJ it's difficult to defend the claim that we don't know anything about nanoparticles' potential risks.

However, if we dig into the research base it becomes equally difficult to say that all these data are conclusive. A recent analysis found that much of the "nanotoxicology" research is done in vitro, focusing on acute toxicity and mortality induced by native nanoparticles, with limited relevance to human health or environmental impacts and little attention to consumer products.¹ We are still a long way from having the knowledge base needed to develop quantitative tools for predicting nanomaterial behavior. These knowledge gaps have been laid in numerous documents, including an ICON workshop report on predicting nanobiointeractions.

Taken as a whole, the collected research does lead to a few conclusions that have immediate relevance, albeit mostly to people working directly with nanoparticles as opposed to consumers. Simply put,

1. Nanoscale materials may act in ways different from their non-nanoscale analogs.
2. Different physical and chemical properties may result in different biological interactions.
3. Some of these interactions will be unwanted.

These facts suggest that it is prudent for people handling native nanoparticles in the workplace or research lab to take reasonable precautions to avoid exposure to nanomaterials.

Temptation #3: Basing Risk Management Decisions on Non-Nanoscale Materials

As quantitative hazard and exposure assessments are still lacking for most nanoparticles, it is tempting to base risk management decisions on non-nanoscale analogs. But Facts # 1 and 2 argue against this approach. Say it with me, "Nanotubes ‚ Synthetic Graphite." In the meantime qualitative risk management tools such as control banding are being investigated for application to nanoparticle workplaces.²

This particular approach uses task-specific information about the form of the nanomaterial and the duration of the task along with any known hazard information from the non-nanoscale analog to make common-sense recommendations for safe handling. It may make sense to adopt a control banding approach in the interim as more quantitative assessments are developed. General guidance is also available from various governmental agencies³ as well as at the GoodNanoGuide.

The state of knowledge of nanomaterials' environmental, health and safety impacts is in an awkward phase where we have just enough information to believe there may be reason for caution but not enough upon which to base robust quantitative risk management decisions. Much more information is needed to inform risk management in the workplace and decision-making in the marketplace.

This information needs to be based on sound science that utilizes validated techniques and is more accessible to people outside of government and industry. Avoid the temptations to generalize or mischaracterize the nano-EHS literature or seek lazy solutions to risk management. I believe we can work safely with nanomaterials but only if we acknowledge the unknowns, communicate honestly about them and redouble our efforts to reduce them.

All opinions expressed in this piece are my own and should not be taken as the opinions of the International Council on Nanotechnology, Center for Biological and Environmental Nanotechnology or Rice University.

References

1. Ostrowski, A.D., et al., Nanotoxicology: characterizing the scientific literature, 2000-2007. Journal of Nanoparticle Research, 2009. 11(2): p. 251-257.
2. Zalk, D.M., S.Y. Paik, and P. Swuste, Evaluating the Control Banding Nanotool: a qualitative risk assessment method for controlling nanoparticle exposures. Journal of Nanoparticle Research, 2009. 11(7): p. 1685-1704.
3. National Institute for Occupational Safety and Health, Approaches to safe nanotechnology: Managing the health and safety concerns associated with engineered nanomaterials, Department of Health and Human Services Centers for Disease Control and Prevention, Editor. 2009, National Institute for Occupational Safety and Health.