First published in Nature Nanotechnology, 5 March 2014.  Nature Nanotechnology 9, 159–160 (2014) doi:10.1038/nnano.2014.43 [Link]

Ten years after the publication of an influential report on the uncertainties in nanoscale science and engineering, are we in danger of creating a new metaphorical grey goo?

In 2004, the Royal Society and Royal Academy of Engineering (RS-RAE) in the UK published the report Nanoscience and Nanotechnologies: Opportunities and Uncertainties [1]. At the time it was widely speculated that the report arose from concerns expressed by Prince Charles over the possibility that nanotechnology could lead to a ‘grey goo’ scenario where self-replicating ‘nanobots’ destroy life as we know it [2]. Outlandish as the alleged motivation was (and Prince Charles was quick to downplay reports of his grey goo concerns [3]), the resulting report set the pace for the next decade of global research into the potential impacts of nanotechnology — and how to avoid them.

Around the time the report was commissioned, concerns over the potential unanticipated consequences of nanotechnology were beginning to gain wider traction [4]. Essays like Bill Joy’s ‘Why the future doesn’t need us’ [5] were raising concerns in the public domain, and professional interest in possible human health and environmental impacts of nanoscale science and engineering had been growing steadily for the previous decade. As far back as 1992, for example, the journal Nature published a Correspondence raising the issue of possible asbestos-like behaviour of carbon nanotubes [6] — less than a year after Sumio Iijima published his seminal work on the structures [7]. And during the 1990s, particle toxicologists began revealing increasingly unusual biological interactions associated with certain nanoscale particles [8].

During this period, the US and other countries were beginning to invest heavily in nanoscale science and engineering as an engine of economic growth [9]. Alert to a potential public backlash against the technology that could undermine this public investment (nanotechnology at this point was riding hot on the heels of a widespread European rejection of genetically modified foods), research agencies began investing in the possible implications of nanotechnology [10]. In the US, the National Nanotechnology Initiative pulled together expertise on the possible impacts and benefits of the new technology [11], and health and environmental impacts were integrated into the country’s national research and development strategy [12]. It was, nevertheless, the RS-RAE report that emerged as the defining document for research into the potential impact of the field. The report was ostensibly focused on evaluating both the opportunities and uncertainties of nanotechnology. Under the leadership of Professor Dame Ann Dowling — head of the Department of Engineering at the University of Cambridge — a select working group of experts from multiple fields set out to define what is meant by nanoscience and nanotechnologies; to summarize the current state of knowledge; to identify specific applications; to carry out a forward-look to see how the technologies might be used in the future; to identify what health and safety, environmental, ethical and societal implications and uncertainties might arise; and to identify areas where additional regulation needed to be considered. The working group received input from over 200 experts in nanotechnology development, use, safety, ethics and governance from around the world. Based on this input, and their own expertise, the group produced arguably the most comprehensive and accessible assessment of nanoscale science and technology at the time.

Despite their broad remit, however, the working group skipped over the many potential benefits of nanotechnologies in their recommendations, and focused almost exclusively on the potential risks and uncertainties. Of the 21 recommendations arising from the report, 19 of them addressed potential implications of the emerging science and technologies. Some of the recommendations were specific to UK investment in nanotechnology at the time, but others responded directly to the global dearth of knowledge on potential risks alongside hints of potentially harmful behaviour. The message was clear: whatever you might think about the economic and societal benefits of this new suite of technologies, extensive further investment into possible applications would be foolish without direct investment in research and action on potential implications.

Figure 1 The number of peer-reviewed papers published each year on the environmental, health and safety impacts of engineered nanomaterials. Source: nanoEHS Virtual Journal [13].

Figure 1 The number of peer-reviewed papers published each year on the environmental, health and safety impacts of engineered nanomaterials. Source: nanoEHS Virtual Journal [13].

Since 2004, peer-reviewed publications addressing the health and environmental impact of engineered nanomaterials have skyrocketed. A search of the nanoEHS Virtual Journal [<a href=”#13″>13</a>] (a database of articles related to the environmental and health impacts of nanotechnology that have been published in different journals) returns 139 peer-reviewed papers related to nanomaterial risk published in 2003; the same search returns 1,326 papers published in 2013, with a rapid increase in the rate of publication occurring in 2006 — just two years after the RS-RAE report (Fig. 1). Although it would be disingenuous to suggest that this increase was solely due to the report, the document clearly stimulated global movement towards investing more heavily in research around potential health and environmental implications of engineered nanomaterials.

The result of this investment is an understanding of the impacts of nanotechnology that extends further than anyone might have imagined in 2004 [14]. An extensive body of published data on the human and environmental impacts of mainstream metal and metal oxide nanomaterials now exists, and recent research has shed important light on the potential health effects of carbon nanotubes [15, 16] — a field that was all but ignored between 1993 and 2004. Global- risk-research approaches for nanoscale materials have been addressed by a number of organizations, including the Organisation for Economic Co-operation and Development [17]. And chemical safety regulations in the US, the EU and Australia have been evaluated with respect to their applicability to engineered nanomaterials [18].

Although this has been a global effort, there is no doubt that the RS-RAE report was a catalyst for action: a voice of scientific reason and social concern at a time when speculation could have scuppered the nanotechnology enterprise or, worse, led to materials and products that showed a blatant disregard for health and environmental risks. But the report’s legacy is more complex than this. As research
into the health, environmental and societal implications of nanotechnologies has grown, the relevance of this research has become less clear. Spurred on by fears of novel and unique behaviour, millions of dollars have been invested into the risk research of materials that — although they show toxicity at high exposures — don’t always seem to hold the dramatic risk surprises that some thought they would. This isn’t always the case — carbon nanotubes again stand out as a material that needs to be used with caution. Yet substances like silver, titanium dioxide and cerium oxide nanoparticles are failing to show unambiguous indications of substantial and unusual health and environmental impacts, encouraging researchers to dig ever-deeper to discover the assumed-to-exist evidence of novel risk.

This is the darker side of the RS-RAE legacy — and one that probably could not have been anticipated. Legitimate questions were asked by the RS-RAE working group over what could possibly go wrong with these new, and esoteric, materials. But this set the global risk research and regulation community on a path that has, over time, worn a rut that is proving hard to get out of. The speculation of possible risk has developed into an assumption of as-yet-to-be-discovered risk.

This is not to say that there are not significant risks associated with nanoscale materials — as research continues to show, nanoscale materials can and do interact with biological systems in unusual ways. Yet by focusing on only a small group of materials that grabbed headlines early on, researchers run the danger of missing emerging materials and products that may present greater challenges than those initial nanoscale materials.

Ten years ago, the RS-RAE working group admirably turned speculation over grey goo into a solid foundation of an evidence-based approach to plausible nanoscale material risks and realistic risk avoidance strategies. Today, amidst the undeniably important progress that has been made following the report, it has to be wondered whether researchers have created a new, metaphorical grey goo in their quest to respond to speculative nanomaterial fears. If so, maybe it’s time to once again use speculation as a lever to shift research and action on risks and benefits towards evidence-based approaches to the next generation of advanced materials and products emerging from nanoscale design and engineering.


1. Nanoscience and Nanotechnologies: Opportunities and Uncertainties (The Royal Society and The Royal Academy of Engineering, 2004); publications/2004/nanoscience-nanotechnologies

2. Brave new world or miniature menace? Why Charles fears grey goo nightmare. Royal Society asked to look at risks of nanotechnology. The Guardian (2003); apr/29/

3. Prince warns of science ‘risks’. BBC News (2004);

4. Roco, M. C. J. Nanoparticle Res. 5, 181–189 (2003). DOI: 10.1023/A:1025548512438

5. Joy, B. Wired 238–262 (April, 2000). Link

6. Coles, G. V. Nature 359, 99 (1992).  DOI: 10.1038/359099b0

7. Iijima, S. Nature 354, 56–58 (1991). DOI: 10.1038/363603a0

8. Oberdörster, G. Phil. Trans. R. Soc. Lond. A 358, 2719–2740 (2000). DOI: 10.1098/rsta.2000.0680

9. Nanotechnology Research Directions: IWGN Workshop Report. Vision for Nanotechnology R&D in the Next Decade (National Science and Technology Council Committee on Technology Interagency Working Group on Nanoscience, Engineering and Technology, 1999); IWGN.Research.Directions

10. National Research Council Implications of Nanotechnology for Environmental Health Research (The National Academies Press, 2005). Link

11. National Nanotechnology Initiative; Research and Development Supporting the Next Industrial Revolution. Supplement to President’s FY 2004 Budget (Subcommittee on Nanoscale Science, Engineering and Technology, Committee on Technology, National Science and Technology Council, 2003);

12. US Congress 21st Century Nanotechnology Research and Development Act Public Law 108–153, Report No. S.189 (108th Congress, 1st session, Washington DC, 2003); http://olpa.

13. nanoEHS Virtual Journal;

14. National Research Council A Research Strategy for Environmental, Health, and Safety Aspects of Engineered Nanomaterials (The National Academies Press, 2012). Link

15. Poland, C. A. et al. Nature Nanotech. 3, 423–428 (2008).

16. Sargent, L. M. et al. Part. Fibre Toxicol. 11, 3 (2014). DOI: 10.3109/17435390.2010.500444

17. Kearns, P., Gonzalez, M., Oki, N., Lee, K. & Rodriguez, F. Nanomaterials: Risks and Benefits 351–358 (2009). DOI: 10.1007/978-1-4020-9491-0_27

18. Hodge, G., Bowman, D. & Maynard, A. D. (eds) International Handbook on Regulating Nanotechnologies (Edward Elgar, 2010). Link

Image: CSIRO ScienceImage 1087 Carbon nanotubes being spun to form a yarn.  Wikimedia Commons


Andrew Maynard