Interview
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Spoonful of Caution with NANO HYPE Andrew Maynard speaks about addressing the environmental effects of emerging nanotechnologies.
NAOMI LUBICK
NAOMI LUBICK
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anotechnology promwhether using sunscreen with ises exciting new ideas, titanium dioxide (TiO2) nanofrom space elevators particles is dangerous, but he tethered to earth by and other researchers and polnanotubes to heat conduction icy makers have been attemptand energy storage in nanoing to hammer out just how to sized spaces. The potential revgo about assessing those risks. olution also brings likely perils, ES&T reporter Naomi Lubick and some voices are spreading recently sat down to talk with the word of caution. One of these Maynard about the risks and people is Andrew Maynard, the hazards of nanotechnology. chief scientist of the Project on Andrew Maynard has been a vocal advoEmerging Nanotechnologies at cate for risk and hazard assessments of How did you become interested in nanotechnology and nanomaterials? the Woodrow Wilson Interna- nanomaterials. tional Center for Scholars. In 1989, I did my Ph.D. at the The project’s efforts to bring more awareness University of Cambridge (U.K.), and I joined the to both scientists and the public about the state microstructural physics group, which was a group of nanotechnology and its potential risks recently that was using cutting-edge transmission electron brought Maynard to a public meeting, where he ilmicroscopy to look at very, very small particles. I lustrated the potential hazards by pulling out a botwas using high-resolution analytical electron mitle of Dr. Gunderson’s Powdered Nano Calcium and croscopy to see if you could apply these materials Magnesium dietary supplement. From the puff of science techniques to measure ambient nanoparpowder as he opened the bottle to the final mixticles—atmospheric nanoscale particles floating ture in a drinking glass, Maynard illustrated some around from various sources. of the ways in which consumers could be exposed Of course, back in the 1980s and beginning of the to nanomaterials—dangerous or not—while empha1990s, nobody was truly interested in exposure to sizing how little is known about nanomaterials with nanoparticles. So I went from here into occupational regard to risks and hazards. health and spent the next several years trying to unMaynard says that people don’t often ask him derstand exposure to much larger particles.
© 2007 American Chemical Society
APRIL 15, 2007 / Environmental Science & Technology n 2661
Ames Rese arch Center, NASA
In terms of that interest level, nobody was really manufacturing nanomaterials in large amounts at the time, were they? People have been using nanoscale particles and structures for many years. What has changed is that over the last two decades, we’ve been able to see what the structure is and to intelligently manipulate it, whereas in the past it was a little bit of a black box: you threw stuff together and it did something. Even when I was working at Cambridge, a lot of the research was looking at nanoscale catalysts: we would study surfaces with incredibly small platinum particles on them—nanoparticles—and examine how these worked in commercial applications. Nanomaterials were around then, but people didn’t use the term “nanotechnology”. . . . In terms of the data out there, some of the first papers demonstrating that nanoscale materials behave differently in the body go back to the beginning of the 1990s. . . . If you go back 17 years, you can see the beginnings of this field emerging. But, really, people hadn’t taken it that seriously until the end of the 1990s.
This "neural tree" composed of carbon nanotubes can use electronic, acoustic, and other kinds of signals to switch at its branching junctions, much like a biological system does, for complex computing functions.
Why now? Why did it take so long? What you saw were people looking in areas that piqued their interest or people who had concerns about very narrow areas, but nobody was there to see the big picture and to understand how that research affected things in the long term, which is why it rumbled on for nearly 17 years. It’s only now that people are beginning to realize that not only is this an important area of research, but nanotechnology is moving so fast that we’re in danger of being left behind in terms of the knowledge we need. We’re not already left behind? Well, it’s very hard to tell. Certainly, it’s very clear that where we are now, you’ve got nanotechnology products out there which raise some concerns, and we don’t have the information we really would like to have to deal with them. So, in that respect, we are behind the curve. 2662 n Environmental Science & Technology / APRIL 15, 2007
Is this different from other materials, other chemicals? Like asbestos, for example? We’re not in an ideal position, but we’ve done better here than we have in many cases in the past. . . . Asbestos is an obvious example, but [with] almost any sort of material or chemical which has led to health impacts or environmental impacts, the model has been: you develop it, you put it out there, people get sick, you work out what’s causing it and reduce the risk. It’s a very reactive response. What we’ve tried to do with nano, and to a certain extent we’ve begun to achieve it, is have a proactive response, so you understand what the risks are before they occur, and avoid them. So why in the case of nanotechnology is this kind of forethought happening? It’s really been a fusion of a number of things. . . . Toward the end of the 1990s, there was this swirl of concern over exposure to fine particles, first of all the PM2.5 [particulate matter less than 2.5 micro meters in diameter]. Then, just underlying that, there was concern about the potential impact of much smaller particles—the 100-nanometer [nm]-diameter particles. So you had that aspect of research. . . . And then you had this other community developing new nanoscale materials, and that was being hyped up in a very big way, [with] people talking about the next industrial revolution. It was a confluence of the two camps, I think, in many ways, looking back, and relatively serendipitous that suddenly these things came together. [This] is possibly why this whole debate about understanding and monitoring the risk came in at an early level. [Also], if you look at the people that have really been driving the nanotechnology, the Mike Rocos [of the National Science Foundation] of this world, they have always had a fairly good grasp of the big picture, the idea that you can’t really introduce a new technology without understanding some of the wider consequences. Could you compare it to nuclear research [the Manhattan Project]? They didn’t know what they were doing when they built the bomb. That’s probably not a good analogy! Hopefully we’ve learned a little bit from nuclear research. But, interestingly, there is still the sort of mentality where science and technology are pursued without too much thought to the broader consequences. One thing that has changed is [that] information flows much more freely these days. So if somebody in one place comes up with a new technology and they start applying it without thinking too carefully about the consequences, it’s very easy for somebody elsewhere to get that information and to start feeding it into the debate, I think, to a greater extent than has ever been possible before. That feeds into questions about ONAMI [Oregon Nanoscience and Microtechnologies Institute], for example, a green chemistry nonprofit coalition that is looking at the safety of nanomaterials. . . . Are these green nanomate-
It’s also more expensive, right? You could argue that at very early stage[s], if you try to develop a new way of doing things, yes, potentially it is more expensive. You’ve got to invest more in it. But in the long run, if you are developing a new framework for how to do things, I’m sure you could spark different ways of doing things that aren’t necessarily more expensive. . . . If you look at our Nature paper [2006, 444, 267–269] listing the five grand challenges, the challenge addressing modeling nanomaterial behavior does touch on this idea of engineering in safety, or “safety by design”, which is beginning to get into the paradigm of green chemistry and green nano. Do you want to talk a little bit about the five challenges? There were a number of drivers here; one was a lack of any coherent strategy to deal with the inherent or potential risks associated with nanomaterials. Another one was the difficulty in motivating the scientific community to really engage in high-quality, risk-based research. . . . There is little reward for a scientist engaged in this sort of research. It’s not as if you are breaking new boundaries [or] developing new intellectual property in many cases, . . . so that doesn’t really encourage progressive, cutting-edge science, but it doesn’t have to be like that. . . . One of our aims was to try to energize the international research community to address the academic and the intellectual challenges that we face here, to rise to those challenges and engage in a high quality of science in a very effective way. . . . Although we wanted to set a framework for a strategic approach to understanding risk, these challenges don’t represent a strategy in itself. They’re really a foundation on which others could build an effective strategy. In terms of the weighting of some of these issues, what are the things you would like to see right away? In an ideal world, you’d want all this information now, but it’s not going to happen. Research takes a long time. So we tried to build that into the timeline. . . . The things we need right away [are] ways of minimizing any potential impact of the nanotech-
nologies which are already out there at the moment, and specifically those that present the greatest risks to health. That means products and processes involving very fine powders, or liquids containing very fine particles—the sort of stuff that can get into the body and that you can be exposed to and could sometimes disperse into the environment. Rice Universit y
rials and safety measures things that people are actually going to adopt? There’s more freedom of information, but there are also more people out there who do not know that the information exists. That general paradigm of trying to understand a system and making it better, or addressing a problem and using the technology and tools you have at your disposal to make it better, is an extremely attractive paradigm. I would love to see it take root, not only with the things that ONAMI [is] doing, but the general idea of working in a way that is more benign, more helpful to the environment in which we live. Now, whether that will take off in a big way, it’s very hard to tell. It is a very clear paradigm shift in the way we do things, but as I say, very attractive.
Nanomaterials rarely go naked. The polymer coating on this single-walled carbon nanotube makes it more soluble and possibly more toxic in aqueous environments.
We [also] need effective ways of working with these materials when we really don’t have all the information we need to understand the risk. . . . In an approach called control banding, if you don’t know the exact risk associated with a material, you make a rough guess at it, according to how much of the material you are using and what the material is like. Then you select a control approach based on this assessment, whether that is relying on general ventilation, local exhaust ventilation, containment, or whatever. But beyond that, you’ve got very specific issues, such as how do you measure exposure. The first step toward understanding what the impact might be of an engineered nanomaterial and minimizing that impact is to know how much you are actually being exposed to, so you need methods and instruments for doing that, and those don’t exist at the moment. This is why our first big challenge is developing appropriate instruments for monitoring exposure.
Some very cutting-edge researchers are still struggling with the nitty-gritty of how to measure something in air—that’s the kind of thing that you’re talking about. Why is it so difficult? Measuring stuff in air is more complex than you might imagine, especially when you’ve got very, very fine particles. The next problem is developing cheap instruments . . . and the third problem is that nobody is quite sure of what they should be measuring. If you think of particles in the air, you can count the number of particles, you can measure the mass of material, you can measure particle surface area, or a number of other parameters. Say it costs you $10,000 to get an instrument that measures the number of particles, $10,000 for an instrument that measures the mass, $15,000 for one that measures the surface area—you’re not going APRIL 15, 2007 / Environmental Science & Technology n 2663
to invest in all of those instruments if only one of those parameters is important. But if you don’t know which one it is, you’re really stymied.
Joseph L auher, SUNY Stony Brook
What if it turns out that they’re all important? Well, almost definitely with the range of nanomaterials being produced, there [are] going to be some materials where particle number is important, some where surface area is important, some where mass is important. So you can’t simplify it down to saying there’s only going to be one instrument, which is exactly why in our challenge we say what’s needed to break this impasse is to have a cheap instrument which measures all three of the key parameters— numbers, surface area, mass—simultaneously. . . . So if you decide to change your mind about what’s important, or you come up with a new process and something else becomes important, you can use the same instrument.
C 60 molecules—colloquially known as buckyballs or fullerenes after Richard Buckminster Fuller—can carry other atoms inside their lattice and might eventually find applications as superconductors, but in certain settings, the nanoparticles have been shown to be deadly to cells and microbes.
There’s such a variation in the nanomaterials that are out there already. Even in one product sample, you have variation (from size to the outer coatings). How do you deal with that? This is where it comes down to dealing with complexity. Again, in an ideal world, the way we try to deal with risk is that we have a paradigm where you have all the information you need. You plug this information into the model and out comes an assessment of what the risk is and how to manage it. To do this with all nanomaterials, you would need specific information about every material that’s out there. For instance, you would need to know if you have 10-nm particles and you change them to 11 nm, does that suddenly change everything? Clearly you cannot use a conventional approach to deal with this. There are two ways forward here, and they are actually quite complementary. In the long run, . . . you develop systems or models that can predict, to a certain extent, the risk. So if you have a specific 2664 n Environmental Science & Technology / APRIL 15, 2007
type of material, specific size, specific shape, and so on, you can plug that into the model and it will give you a reasonable idea of what the risk or critical issues are likely to be. That makes it a lot easier if you have one particular base product and have 100 variations of that, in terms of size, composition, or anything, rather than [doing] all the tests on every single one of those variations. . . . [However,] two things are clear: one of them is you are never going to predict everything. And no matter how much you can predict, somebody is always going to come up with something that doesn’t fit the model easily. . . . Say it takes 20 years before we can predict nanomaterial behavior sufficiently. . . . We’ve got to deal with that 20-year gap where all these things are being produced and we can’t deal with them. The only option here is to have what I would call subjective approaches to handling risk, where you don’t have all the information and yet you have to make some kind of decision on how you move forward.
The pessimistic point of view is that people are going to have to deal with these materials in the future. Is there anything you can say will be OK or will be harmful? It all depends on context. Plenty of things are probably going to be fairly benign, but as with everything, we’ve got to understand that . . . if you do something stupid even with the safest of things, you can cause damage. In terms of the other end, things that cause harm, there are certainly materials that are coming along which are more worrisome than others. For instance, if you compare TiO2 nanoparticles to single-walled carbon nanotubes, I think the evidence at the moment indicates that there are likely to be far more dangers associated with carbon nanotubes. . . . That doesn’t mean that we can be complacent about the TiO2 ; we still have to know how to use it safely. Nanotubes are interesting because they are such a new type of material, and there is a lot more excitement about the ways they can be applied—all the way from very simple applications like creating materials that are very light and very stiff, to fantastical applications like tethering a satellite to the earth to form a space elevator. But because carbon nanotubes are so new and so unique, there are probably more questions that are harder to answer about this material than with many other materials. Very, very thin, very long—a single-walled nanotube is very flexible, so it can bundle up and form particles that are very tiny and dense or very large and airy. On top of that, it’s got unique chemical properties: the surface of it is very unusual, and then depending on how it’s produced and how you functionalize the surface—what’s attached to it—it behaves in very different ways. So there are really many unknowns. Is there something you want to mention that we haven’t touched on? Yes, public engagement, and what the people using nanotechnology think about it. A hundred years ago,
Nanotechnology relies on interactions on surfaces like this one, dotted with gold and silicon atoms. Nanometerscale surface interactions may be very different than those at larger scales.
Is it working? I’ve seen public forums but not that many public people, or scientists, for that matter. I’m not sure whether it’s working or not. We’ve got a long way to go. The last survey we did indicated that something less than 30% of the U.S. population are familiar with nanotechnology. A far smaller proportion actually know what it is, and how it’s going to be affecting their lives. . . . Also, what I don’t see is communication going the other way, to the scientists. . . . I think there’s a very real need for the scientific and technical community to understand the interface between what they do and the society their work impacts on. . . . Science is not done in a vacuum; it’s not done in isolation. I would say it’s a social function. Although scientists like to think that they are independent and doing their own thing, science does have wider social consequences. At the moment, there is very much this hierarchy: the scientific community believes that they have right on their side . . . and that the more that they tell people it’s OK—they’ve got the science right—the more likely things will be OK. But the person using the technology doesn’t necessarily just want to be told by the scientists that it’s OK. They want to be able to understand and decide for themselves. What about the car example? People don’t really care how cars work, as long as they get them places. That is true, but if you make the decision [that] we aren’t going to let people know how it works, and
you tell people that they don’t need to know how it works, people will object. It’s the right-to-know idea. People don’t necessarily want to go and look at the information if it’s there, but they don’t want to be prevented from having access to the information.
I understand that although the U.S. has been a leader in nanotechnology, that’s changing. I think there may be a possibility of this happening—particularly when it comes to understanding and managing risks. The U.S. was first to grab onto the concept of nanotechnology and run with it. . . . I think that, because of the U.S. approach to nanotechnology, research into understanding risk has been very disjointed. . . . It’s been science-based, not policybased. It’s not been based on what we need to know; it’s been based on what researchers come up with. It doesn’t matter how much money you put into research, it doesn’t matter how brilliant the research is—if you can’t use it at the end of the day, you haven’t really made that much progress. Are there any questions you are surprised that no one asks? I’m surprised how infrequently I’m asked “I have a sunscreen with TiO2 nanoparticles in it . . . is it OK?” Assessing risks versus benefits is subjective, but how do you decide without all the necessary information? Also, there are future hot spots with food—the use of nanotechnology in food packaging and in food itself. These are all in the research phase [and are] also a bigger issue [because they are] so crossdisciplinary. . . . Rice Universit y
Brookhaven National L aboratory and Argonne National L aboratory
scientists and technologists did the work, this was transformed into commercial products, and people just lived with them. They didn’t have any say in what was done. But now, with the world shrinking, it seems like the users of technology in society are far more part of the mix of what gets done and what doesn’t get done. And they are stakeholders in new technologies. . . . How [do] you enable them and empower them to make choices, provide them with the information they need to enter into the debate and actually contribute to what’s going on?
The polymers on the surface of this single-walled nanotube guide its placement onto other substrates.
Experts are moving from one field to another, and they may not know what questions to ask. A food company would know what the critical questions are, for example, but a materials specialist who might develop nanotech products for use in foods or cosmetics—do they know enough about toxicology, biological interactions, or even regulations to assess and manage the risks appropriately? The solution is in forming strong cross-disciplinary partnerships, asking questions, and not assuming that you know all the answers. Naomi Lubick is an associate editor of ES&T. APRIL 15, 2007 / Environmental Science & Technology n 2665
