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Nanoparticle safety raises questions

By Seán Ottewell, editor at large

ChemicalProcessing.com

Keywords: nanoparticle and safety

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

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.