Nanoparticle safety raises questions

U.S. initiative focuses on health as well as economic impacts of nanotechnology.

By Seán Ottewell, editor at large

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The U.S. government is revising its strategy on nanotechnology. In early January Washington launched an updated National Nanotechnology Initiative (NNI) strategic plan. This replaces a plan introduced just three years ago, reflecting the speed of progress in the field as well as concerns about the environmental, health and safety (EHS) implications of tiny particles.

The plan sets out the vision, goals and priorities needed to ensure that the U.S. gains growing economic benefits and a better quality of life from nanotechnology and remains a global leader in its R&D. The new strategy is designed to emphasize and clarify the significance that nanotechnology advances will have for the U.S. “Exploiting the full value that nanotechnology offers depends on sustained R&D. Barriers to innovation and technology transfer need to be lowered. Researchers, educators and technicians with new skills are required. Furthermore, nanotechnology must be developed responsibly,” explained Clayton Teague, director of the National Nanotechnology Coordination Office, which supported the interagency effort in developing the plan.

To realize the NNI vision for a field which they say already is worth $12 billion, the participating agencies are collectively working toward four goals:

  • advancing a world-class nanotechnology R&D program;
  • fostering the transfer of new technologies into products for commercial and public benefit;
  • developing and sustaining educational resources, a skilled workforce and the infrastructure and tools to advance nanotechnology; and
  • supporting responsible development of nanotechnology.

The fourth goal is especially topical for the chemical industry because it involves a program of research, education and communication focused on EHS issues as well as the broader societal dimensions of nanotechnology development.

One of the critical research needs identified as part of this goal is developing techniques that predict toxicity before manufacturing. “The rapidly increasing numbers of nanomaterials in development and manufacture, as well as the exquisite sensitivity of a material to its biological microenvironment, makes it difficult to predict biocompatibility or toxicity in humans and the environment,” notes the strategy document.

The NNI wants to move away from the conventional, tiered system of toxicity assays and to develop predictive models for nanomaterials. This will allow physical and chemical parameters of materials to be adjusted early in product R&D — shortening time for toxicity testing from several weeks to hours, the plan says. “It will also provide a labor and cost benefit to the manufacturer, new tools for risk assessment by regulatory agencies, and protection of humans and the environment from harmful exposures.”

A number of industrial-supported initiatives already are looking at the safety of nanoparticles (www.ChemicalProcessing.com/articles/2006/073.html) as is a voluntary effort with the U.S. Environmental Protection Agency (EPA) (www.ChemicalProcessing.com/articles/2007/148.html). In addition, the National Science Foundation and the EPA are soliciting proposals to create a National Center for Environmental Implications of Nanotechnology that would conduct fundamental research and education.

The engineering perspective

 

Chemical engineers, both in academia and industry, already are active in such areas.

For instance, at Washington University, St. Louis, Mo., Pratim Biswas, chair of the Department of Energy, Environmental and Chemical Engineering, has shown that he can independently control the size of the nanoparticles — keeping their properties the same. His technique, which relies on a flame aerosol reactor, also enables the materials to be made in large quantities in scalable systems, opening up prospects for new and unique uses. “The applications are plentiful,” said Biswas. “… If I can make materials of very narrow sizes, I can study the properties as a function of size, which has not been possible in the past, with very precise controls so we can do fundamental research. And that allows me to come up with new applications.”

However, Biswas was quick to point out that with all these new applications come budding new fields of study — particularly nanotoxicology. In it, nanotechnologists join forces with biologists to determine the safety of particles. For example, a particular size particle may provide the best effects in a cosmetic but manufacturers must ensure that it doesn’t cause toxic effects in a person’s body.

“We don’t want to just release it to the environment. The general feeling is that you have to be proactive, make sure everything is OK and then go, so here you are trying to be as cautious as possible,” he said.

Meanwhile, many chemical companies, of course, also are looking at nanotechnology.

BASF, Ludwigshafen, Germany, for instance, has already invested more than 180 million Euros in research to put nanotechnology to practical benefit.

The company has developed new synthesis routes for plastic foams with nanodimensional pores that prevent gas molecules from colliding and therefore reduce the material’s ability to conduct heat by more than 60%; such foams should suit applications in refrigerators, buildings and airplanes.

The firm also has developed cube-shaped nanostructures known as metal organic frameworks (MOF). Thanks to their nanodimensional pores, MOFs can store energy-rich gases such as natural gas. Because the nanocubes also store hydrogen, they could have a future use as energy sources for electronic devices.

Then there are the next-generation sources for illumination — organic light-emitting diodes (OLED). BASF scientists reckon that they require only half as much energy as conventional energy-saving light bulbs.

Some of the company’s nanotechnology developments already have reached the marketplace. For instance, the latest Audi A4 and A5 automobiles feature its Ultradur High Speed nanotechnology-based engineering plastic in their door control devices.

The material was chosen because of its low warpage, which ensures a rigid housing, while good flowability allows simple injection molding (Figure 1).

Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.

Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.

Similarly, the firm has just launched its first three Ultramid High Speed products. Filled with glass fiber or mineral nanoparticles, they are said to exhibit marked improvements in flow properties and much better resistance to heat aging at high temperatures (Figure 2).

Figure 2. Polymer filled with glass fiber or mineral nanoparticles better resists heat aging at high temperatures. Source: BASF.

Figure 2. Polymer filled with glass fiber or mineral nanoparticles better resists heat aging at high temperatures. Source: BASF.

BASF treats risk assessment as a crucial aspect of its research. “Safety research parallel to the dynamic development of the nanosciences is essential for their sustainable use,” explained Rüdiger Iden, the company’s spokesman for nanotechnology. So, the company is involved in a number of German and wider European projects considering the safety of nanotechnologies.

Lack of guidance

 

The Project on Emerging Nanotechnologies (PEN), Washington, D.C., undoubtedly is pleased that EHS issues are so high on the NNI agenda. Launched in 2005 by the Woodrow Wilson International Center for Scholars and The Pew Charitable Trusts, PEN is dedicated to helping business, government and the public anticipate and manage possible EHS implications of nanotechnology.

Last December PEN released the results of a survey of New England-based nanotechnology companies aimed at discovering how firms in almost every sector of the economy address the possible EHS impacts of new nanoscale materials and products. The survey indicated that as nanotech industrial and consumer applications enter the market, U.S. companies need more information and guidance from suppliers, trade associations, government regulatory bodies and others to effectively manage risks.

“Many smaller firms recognize the need to address risks proactively but few have the resources to do so. At present, the majority of survey participants expect to rely on suppliers to provide nanomaterial risk management information in the form of Materials Safety Data Sheets (MSDSs). But these do not always reflect the latest health and safety information, and regulatory or consensus guidance for these new materials is lacking,” noted John Lindberg of the University of Massachusetts Lowell, Mass., the study’s principal investigator.

David Rejeski, director of PEN, expanded on this important problem: “The current MSDS for carbon nanotubes sold over the Internet treats them as graphite — the same material used in pencils — despite nanotubes bearing no more than a passing resemblance to this material. Clearly, companies are not being given the guidance they need. The findings from this study are consistent with other surveys of nanotech businesses in California, New York and around the world. Firms are flying somewhat blind into the future and need a clear set of rules, a sense of the emerging regulatory landscape and access to relevant research on risks in order to ensure both nanotechnology safety and profits.”

In an earlier (August) report, PEN also called for initiatives to tackle the low level of awareness generally among the U.S. public.

“Even though the number of nanotechnology-enabled consumer products — from dietary supplements to skin products to electronic devices — has more than doubled to over 500 products since 2006, the ‘needle’ on public awareness of nanotechology remains stuck at disappointingly low levels,” warned Rejeski.

“Efforts to inform the public have not kept pace with the growth of this new technology area. This increases the danger that the slightest bump — even a false alarm about safety or health [intoxication due to a bathroom sealant supposedly based on nanotechnology caused a scare in Germany (see www.ChemicalProcessing.com/articles/2006/073.html), Ed.] — could undermine public confidence, engender consumer mistrust and, as a result, damage the future of nanotechnology before the most exciting applications are realized. If they do not effectively engage a broad swath of the public in steering the course of nanotechnology, government and industry risk squandering a tremendous opportunity,” he cautioned.

“There is an urgency to nano-EHS research that affects the entire NNI investment,” stressed Vicki Colvin, director of the Center for Biological and Environmental Nanotechnology at Rice University, Houston, and executive director of the International Council on Nanotechnology, at a hearing of the House Committee on Science and Technology in late October. “Innovation in nanotechnology is being threatened by the uncertainty about its risks. We need this innovation more than ever right now.” Interestingly, she called for a detailed strategy for nano-EHS research no later than fall 2008.

Such concerns extend well beyond the U.S. For instance, a 2007 report from the Science and Research Policy Section of the European Union’s Community Research and Development Information Service, Brussels, Begium, warned that lack of toxicity data on nanomaterials is a challenge to the safe commercialization of nanotech products.

“The lack of toxicity data specific to nano-materials is a repeating theme in this and in other studies related to nanotech EHS concerns,” said Andrew Maynard, chief scientist for the project.

Meanwhile, a 32-page report released in December by insurance market Lloyd’s of London, London, U.K., cautioned that the assessment of whether or not nanoparticles harm people has barely begun. “Currently almost all regulation of nanotechnology is done using existing mechanisms,” it said. “Stakeholders in nanotechnology are divided on whether specific regulation is required. However, the ‘wait and see’ approach is increasingly becoming a dangerous way to determine the risks.”

The report speculated about a whole range of large-scale disasters that nanotechnology might prompt — for example, workers involved in nanoparticle manufacture developing chronic illnesses. Lloyd’s noted that, although the real risk of chronic health effects remains unclear, nanoparticles can enter the body and so insurers “would be prudent to consider adverse scenarios.”

The report pointed out the positive role the new materials could have on safety, such as the creation of cars that could better absorb the impact of a crash, but also warned that while nanoparticles are relatively cheap, can be manufactured in large quantities and are already used in consumer products, they can be highly reactive.

Food for thought

Human consumption of materials containing nanoparticles already is a particular area of concern.

One major driver was the announcement in March 2007 by researchers at University of California, San Diego (UCSD), San Diego, Calif., that iron-containing nanoparticles being tested for use in several biomedical applications can be toxic to nerve cells and interfere with the formation of their signal-transmitting extensions (Figure 3).

Figure 3. Cells exposed to no (left), low (center) or high (right) concentrations of iron oxide nanoparticles differed in formation of thread-like extensions called neurites. Source: UCSD.

Figure 3. Cells exposed to no (left), low (center) or high (right) concentrations of iron oxide nanoparticles differed in formation of thread-like extensions called neurites. Source: UCSD.

“Iron is an essential nutrient for mammals and most life forms and iron oxide nanoparticles were generally assumed to be safe,” said Sungho Jin, a professor of materials science at UCSD. “However, there are recent reports that this type of nanoparticle can be toxic in some cell types, and our discovery of their nanotoxicity in yet another type of cell suggests that these particles may not be as safe as we had once thought.”

A similar warning comes from Germany’s Federal Institute for Risk Assessment (BfR), Berlin, Germany, following an extensive consumer survey it completed. This found that consumers were especially critical of the use of nanomaterials in foods, with particular fears expressed about the unknown consequences of digesting nanoscale particles that are designed to behave in a specific way in the body.

Overall, clearer definitions, terms and standards — along with extensive research into its potential problems — are needed before nanotechnology finds greater use in food products, the BfR survey concluded.

Similar warnings also have been issued by the newly-merged Danish National Food Institute (NFI) and the Technical University of Denmark, both in Lyngby, Denmark. NFI is undertaking a specific project that starts with the hypothesis that the mere nanometer size of matter and its associated large surface area may lead to adverse effects in living organisms including human beings.

Clearly, EHS issues loom large in nanotechnology and the NNI plan and other efforts are essential for helping to ensure responsible development.

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