Nanotechnology is often described as an emerging technology—one that not only holds promise for society, but also is capable of revolutionizing our approaches to common problems. Nanotechnology is not a completely new field; however, it is only recently that discoveries in this field have advanced so far as to warrant examination of their impact upon the world around us.
The value of nanomaterials in many technology areas is very high because of their versatile properties. As a result, the investment in nanotechnology by the U.S. government has had a very steady growth; in 2004 investment from a range of different federal agencies reached nearly $1 billion, noted Kenneth Olden, National Institute of Environmental Health Sciences. Industrial investment in this area is also growing steadily. Today some nanomaterials are already being used commercially. For example, some companies are using TiO2 nanoparticles in sunscreen lotions because they provide transparency to a sunscreen, and are believed to be less toxic than the organic molecules currently used as UV absorbers in many sunscreen formulations. Nanomaterials can also be found in sporting equipment, clothing, and telecommunication infrastructure. The future of nanotechnology is boundless, according to some speakers. Some of the items that exist today were a topic of science fiction a decade ago and have the potential to transform our society very quickly, said Douglas Mulhall, author of Our Molecular Future.
Nanoparticles fall into three major groups: natural, incidental, and engineered, noted Vicki Colvin, Rice University. Naturally occurring nanomaterials such as volcanic ash, ocean spray, magnetotactic bacteria, mineral composites and others exist in our environment. Incidental nanoparticles, also refered to as waste particles, are produced as a result of some industrial processes. The third category of nanoparticles is engineered nanoparticles—these are the particles associated with nanotechnology. Engineered nanoparticles are subclassified by the type of basic material and/or use: metals, semiconductoris, metal oxides, nanoclays, nanotubules, and quantum dots. Within each category the shapes,
sizes, and surface coatings further determine structure and function of these molecules. Each such material has been specifically designed for function, such as the fullerene C60, which is used for fuel cell applications. Very little is known about engineered nanoparticles and how they interact with cells or human organisms, noted Colvin.
BENEFITS AND POTENTIAL NEGATIVE IMPACT OF NANOTECHNOLOGY
Nanotechnology has direct beneficial applications for medicine and the environment, but like all technologies it may have unintended effects that can adversely impact the environment, both within the human body and within the natural ecosystem. While taking advantage of this new technology for health, environmental, and sustainability benefits, science needs to examine the environmental and health implications.
Recently, nanotechnology has received considerable attention from the media. Most of the initial reports have been positive; however, scientists should not forget that not all nanomaterials will be benign, said Kenneth Olden, National Institute of Environmental Health Sciences. Therefore, it is very important to identify the negative aspects of the technology before we introduce it to the marketplace. During the workshop, many speakers and participants spoke of the paucity of data for engineered nanoparticles and cautioned against solely relying on the research of natural and incidential nanoparticles.
Determining toxicity can be complicated because not all engineered nanoparticles are more toxic than fine-sized particles of the same chemical composition. The surface coatings of particles, exposure to UV radiation, and dispersion properties can change the behavior of the particles, noted Eva Oberdörster of Southern Methodist University. For example, in pulmonary studies, whether particles aggregate and then disaggregate once they reach the lung fluids as well as the process for generation of nanoparticles, for example, fumed versus precipitated silica seems to be relevant. David Warheit, of the DuPont Company, suggested that developing a working hypothesis for determination of particle toxicity will depend on the capacity of the particles to cause cell and lung injury, promote inflammation, inhibit macrophage function, and persist in the lung. Finally, Warheit observed that species differences complicate research; for example, rats appear to be particularly sensitive to particle-induced pulmonary toxicity.
Some current hypotheses suggest that some engineered nanoparticles may be more toxic (inflammatory) than other fine-sized particles of identical chemical composition, noted Warheit. This concept is based primarily on a system evaluation of three particle types: titanium dioxide, carbon black, and diesel particles. However, he noted that the current hypotheses are based on a paucity of data.
John Froines of UCLA raised the question whether the research that scientists are doing on airborne particulate matter related health effects has relevance
to understanding potential issues with respect to nanotechnology. He suggested that there are areas where there are significant differences, but there are also places where there are commonalities. For example, most of the ultrafine particles from diesel emissions are in the 10 nanometer range, classifying them as nanoparticles. He suggested that a number of biochemical processes may be similar in both the air pollution particles and the engineered particles.
U.S. GOVERNMENTAL INVOLVEMENT IN ENSURING SAFETY
The potential health and environmental effects of nanoparticles and nanomaterials today raise public concern about nanotechnology. Health and environmental agencies in the United States have the responsibility to provide leadership to ensure the thorough assessment of safety and environmental effects of the new technologies.
Government policy makers need to ensure that nanotechnology is developed as a safe consumer product, said David Rejeski of Woodrow Wilson International Center for Scholars. Because many of the existing governmental regulatory frameworks are 30 to 40 years old—conceived when nanotechnology did not yet exist—they may not be adequate today. Yet, new frameworks have not been proposed.
NIH is working to develop some effective, high output, more informative, and less costly systems and has identified several areas for research in nanomedicine, said William Suk of NIEHS. One of its primary objectives is to obtain a comprehensive database and develop quantitative ways of measuring nanomaterials. The National Institutes of Health defines nanomedicine as the integration between nanotechnology and nanosience. NIH is planning to support research on biological systems and molecules such as proteins, DNA, and RNA and how these molecules interact with each other as well as with environmental agents. The other need that NIH has identified—with the help of about 100 scientists—is to develop the mathematical and analytical tools to interpret measurements. Unfortunately, there are no models and tools yet to quantify the responses in such systems and to interpret what they mean. Thus, mathematicians and chemists need to get involved in the effort to understand the significance of these variations, changes, and readouts in terms of biological processes and subsequent effects on organisms.
Barbara Karn of the Environmental Protection Agency stated that by 2008, the total global demand of nanoscale materials, tools, and devices is projected to be about $29 billion. To ensure that universities and research centers in the United States can perform the highest quality research in this rapidly growing area of technology, the EPA has plans to fund research in the areas of health and environmental effects of manufacturing nanomaterials, exploring topics such as their bioavailability and bioaccumulation. At the same time, there are very real prospects for the use of nanotechnology to extend into the realm of environmental
protection and remediation of contaminated sites or other environmental problems. Thus the EPA also plans to fund research on use of nanotechnology to develop new methods for treatment and remediation.
Likewise, NIOSH is concerned with identifying occupational health risks from nanoparticle exposure and considering how to control the risks, whether through reducing risk or reducing the impact. However, to be in a position to assess risk, additional information is needed regarding toxicity of the materials, how they interact biologically in the body, and what the health effects are resulting from toxicity. Additionally, scientists need to know about the exposures and the potential exposure routes (i.e. whether the material is inhaled, ingested, or absorbed cutaneously), noted Maynard.
Across the federal government, the agencies are coordinating work on nanotechnology through the National Nanotechnology Initiative (NNI). One of the NNI’s goals is to establish research programs to understand the social, ethical, health, and environmental implications of the technology, according to Clayton Teague of the National Nanotechnology Initiative. This goal is being addressed by working groups, center of excellence, and NNI-sponsored workshops. One such working group, the National Science Technology Council’s Subcommittee on Nanoscale Science, Engineering and Technology (NSET), was established in August 2003 to ensure effective communication among the research and regulatory agencies, and to identify specific research needs to support the regulatory decision making for nanoscale materials. Further, the NNI is encouraging inter-and multi-disciplinary research on these issues through centers of excellence and through discussions at a series of NNI-sponsored workshops on toxicology of materials, risk characterization and communication, and risk mitigation, noted Teague.
U.S. policy makers and scientists are not the only ones looking into the potential of nanotechnology. The Canadian government anticipates that nanotechnology will produce lasting social change and economic benefits to the country and also is investing in the development of these technologies. However, the use of these new technologies may pose risks to the environment and human health and are not well understood. To be able to answer the questions posed to them by the public, the Canadian government wants to know the downsides of the new technologies and also how to risk-manage these issues, observed Paul Glover, Health Canada. To risk-manage these issues they need to be put into perspective. Informing people about nanotechnology is critical and challenging, said Glover. Nanomaterials involve multiple substances and mixtures over varying periods of time with varying levels of intensity. Therefore, a substance-by-substance risk assessment approach may not be effective. Assessing the risk of nanotechnology is more complex. According to Glover, scientists will need to
update their risk assessment methodologies to create a multidisciplinary approach including industry; different levels of government; different types of researchers in chemistry, physics, and biology; and research regulatory scientists.
THE RIGHT TIME TO PLAN FOR NANOTECHNOLOGY
Today, we are at the optimal time to begin to study the impact of nanomaterials on human health, said Vicki Colvin of Rice University. We are looking at the birth of a new industry and beginning to address risk in a way that has not been done with any other developing technologies before, that is, well before large amounts of these materials are introduced into the environment or onto consumers. That provides us a unique opportunity to shape a new, emerging area with a lot of knowledge about environmental health issues that we would ultimately face and avoid the problems that have plagued chemistry in the past.
There is a need for increased levels of cooperation between the industries involved, public interest groups, and government parties to find economically viable solutions while still protecting the environment and health, asserted John Balbus, Environmental Defense. This is not a small goal, as it is important that nanotechnology development is done right the first time. Modern history has produced a number of technological advances that had such great promise for revolutionizing society; however, Balbus noted that these advances sometimes occurred at the expense of safety. For nanotechnology, the question is how does the science move forward in a way that best protects the public and gets health and safety right the first time. David Rejeski of Woodrow Wilson International Center for Scholars echoed many of these ideas and suggested that unlike genetically modified organisms where only a segregated sector is involved and risk prevention is more manageable, the impacts of nanotechnology will not be confined to one sector, but will be seen across multiple sectors and multiple products. He further suggested that policy makers need to start thinking about voluntary agreements with industry on the responsible use of nanotechnology and push the development of more models that bring together universities, NGOs, and industry to develop principles and best practices. Finally, Balbus noted that the process for conducting research and determining policy directions needs to be an open process with opportunities for public comment.