Emerging nanomaterials and nano-enabled consumer products are projected to have a significant, global impact on future economic, societal, and quality-of-life issues. The field of nanotechnology in general—and nanomanufacturing processes and nanomanufactured materials in particular—present a new regulatory paradigm for commercial sectors, academics, and government oversight and funding agencies alike. In essense, how do we responsibly maintain the critical balance between the necessity of regulatory oversight and the industry of scientific innovation?
The evolution of nanomaterials requires an unprecedented understanding of materials physical and chemical properties, as well as process design methodologies to tailor intrinsic properties for specific applications. While it is important to understand and formulate a knowledge-base for customized nanoscale materials, structures, and devices, it is also necessary to conduct such activities by incorporating scientifically accepted, consistent, and comprehensive methods. This is the driving force behind commercial, governmental, and academic initiatives to develop and federate accurate materials databases (ICON's forthcoming Good Wiki among them) and to enhance our understanding of relevant concerns to the public for these nanomaterials, related processes, and future nanotechnology-enabled products.
The issues at hand are the extent to which governments ought to regulate manufacturers and suppliers that fall within new nanomaterials categories and the appropriate balance between industrial self-regulation and stringent government oversight. Exacerbating the decision making in this area are inferences of specific toxicity properties that have been reported based on less-than-comprehensive scientific studies, subsequent public dissemination of incomplete information by the media, and the rapid rate of change in science and technology which resists persistent modes of regulation. Environmental health and safety practices have evolved to the point where much of the scaled production and manufacturing of nanomaterials may already be regulated under the current understanding of materials properties, safe handling practices, safeguards, and implementations for consumer products. Yet a range of unanticipated materials have emerged that do not fit established knowledge, understanding, or regulatory practices. As such, there are numerous efforts worldwide studying the toxicity of these materials to establish the necessary information base upon which regulatory criteria will be assessed.
Nanomaterials health and safety information must include data relevant to skin exposure, ingestion, and inhalation by humans. While specific research models are widely accepted within the scientific community, it remains extremely important to refrain from inferential assertions concerning the health and safety effects of specific nanomaterials on humans without conclusive evidence. In this manner, two key scientific studies published over the past year have generated responses from government regulators, along with legal review and analysis.
The basis for the studies was the possibility that carbon nanotubes may exhibit asbestos-like behavior due to similarities existing between the materials, including their small diameter, long length, fibrous structure, and chemical stability in physiological environments (biopersistence). The study by Tagaki, et.al., of the National Institute of Health Sciences in Japan, compares the effects of solutions containing multiwall carbon nanotubes (MWNT), micron-scale fullerenes, or crocidolite asbestos particles in the abdominal cavity of p53+/- heterozygous mice, a common genetically engineered and accepted mouse model. The authors report the observation of granulomas and fibrosis in the mesothelial along with the progression to malignant mesotheliomas for large fractions of subjects injected with MWNT (88%) and crocilodite (79%) solutions. Minimal mesothelial reactions and no mesotheliomas were observed for subjects exposed to the non-fibrous C60 fullerenes. The authors conclude that the results of this study indicate a strong carcinogenic potential for MWNT administered directly to the lining of the abdominal cavity, and that the results exhibit a dependency on the fibrous shape and dimensions of the materials. Additionally, the authors clearly state that prediction of the mesotheliomagenic potential of MWNT for humans could not be completed with these results, and refrain from forming inferences of this kind. In a scientifically responsible fashion, the authors outline the necessary protocols and studies that must be completed to render a more conclusive finding on this subject, and cite specific instances of other materials that have fibrous structural properties similar to asbestos yet exhibit no mesotheliomagenic hazard.
Poland, et.al., conduct a similar study including long and short MWNT, tangled MWNT bundles, carbon black nanoparticles, and long fibers of brown asbestos (amosite). The authors report some compelling results from this study, in particular the lack of granulomas and fibrosis formed in the mesothelial lining for subjects administered with short MWNT, tangled MWNT bundle solutions, as well as the carbon black nanoparticles. while granulomas and fibrosis was observed for subjects injected with long MWNT thereby mimicing the fibrous structure of asbestos. One could infer from this that it may be safe to work with carbon nanotubes within specific size criteria. However, subsequent reports point out a range of flaws with this study, along with numerous inferences that interpolate these results for the prediction of the potential mesotheliomagenic hazards. The study does elucidate follow-on protocols and studies that would be necessary to render these conclusions.
These studies were followed by two key actions by government regulatory agencies.
- Under the guidelines of the Toxic Substance Control Act, the Environmental Protection Agency (EPA) in the fall of 2008 published significant new use rules (SNURs) that pertain to two specific nanoparticles—silica and alumina (Rizzuto 2008)—as well as a federal register notice requiring companies to provide a premanufacturing notice to the EPA at least 90 days prior to importing, manufacturing, or processing materials not on the TSCA register (Gulliford 2008). The EPA is also running a voluntary Nanoscale Materials Stewardship Program; an Interim Report on the program was released last month.
- More recently, the California Department of Toxic Substances Control sent notices requesting health and safety information to over 20 companies that manufacture carbon nanotubes. The first time a state has requested such disclosures, California will require companies involved in the import, export, or manufacturing of carbon nanotubes to disclose information on toxicity, how their products react with the human body, and their environmental impact. While no specific regulations were indicated, the department cited the need to develop the existing body of information on carbon nanotubes, filling gaps to safeguard human health and the environment. In doing so, the department referred to the recent reports that suggest nanotubes could pose the same health risks as asbestos. (Goodman, 2009).
Nanomanufacturing has progressed to the point where we are on the brink of realizing nanotechnology-enabled products on a global scale. Key to the successful implementation of emerging nanotechnologies is the completion of critical materials information databases in order to identify the risks of nanomaterials and establish appropriate measures for safety and protection of the environment. One benefit of such databases is that critical information can easily be incorporated into the product development cycle preventing or minimizing any hazards to workers and consumers. Nanomanufacturing research plays a crucial role in that it may provide the platform for understanding the risks from an early stage, thereby incorporating the knowledge base within the production cycle.
In this article:
- Poland, C., Duffin, R., Kinloch, I., Maynard, A., Wallace, W.A.H., Seaton, A., Stone, V., Brown, S., MacNee, W., Donaldson, K. 2008. Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. Nature Nanotechnology 3(7):423-428.
- Takagi, A., Hirose, A., Nishimura, T., Fukumori, N., Ogata, A., Ohashi, N., Kitajima, S., Kanno, J. 2008. J. Toxicological Sciences 33(1):105-116.
- Monica, J.C. Jr., Monica, J.C. 2008. A Nano-Mesothelioma False Alarm. Nanotechnology Law & Business 5(3):319-333.
- Kane, A.B., Hurt, R.H. 2008. The asbestos analogy revisited. Nature Nanotechnology 3(7):378-379.
- Goodman, S. 2009. California to collect data on carbon nanotubes [Internet]. Greenwire [cited 2009 February 5] 2/2/09. Available from: http://www.eenews.net/Greenwire/2009/02/02/archive/10?terms=nanotech
- Rizzuto, P. 2008. Significant New Use Rules for 56 Chemicals, Including Two Nanoparticles, Issues by EPA [Internet]. BNA Chemical Regulation Reporter [cited 2009 February 5]; 32(44). Available from: http://ehscenter.bna.com/PIC2/ehs.nsf/id/BNAP-7L6T5B
- Gulliford, J.B. 2008. Toxic Substances Control Act Inventory Status of Carbon Nanotubes [Internet]. Federal Register [cited 2009 February 5] 10/31/08. Available from: http://edocket.access.gpo.gov/2008/E8-26026.htm