Stable Isotopic Tracing-A Way Forward for Nanotechnology

Article excerpt

Numerous publications and reports have expressed health and safety concerns about the production and use of nanoparticles, especially in areas of exposure monitoring, personal use, and environmental fate and transport. We suggest that stable isotopic tracers, which have been used widely in the earth sciences and in metabolic and other health-related studies for several decades, could be used to address many of these issues. One such example we are pursuing is the use of stable isotopes to monitor dermal absorption of zinc and titanium oxides in sunscreen preparations and other personal care products. Other potential applications of this tracing approach are discussed.

Key words: isotope tracers, nanoparticles, quantum dots, sunscreen, titanium dioxide, zinc oxide. Environ Health Perspect 114:1486-1488 (2006). doi:10.1289/ehp.9277 available via http://dx.doi.org/ [Online 23 June 2006]

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Nanotechnology is currently one of the fastest growing technical fields that develops methods for the design, production, and applications for materials and devices [less than or equal to] 100 nm in size. There are numerous potential applications arising from nanotechnology which include their use in aerospace, agriculture, security, energy, information technology, medicine, transportation, consumer products, and environmental improvement (Nanoscale Science 2004). Nanotechnology is projected to be a US$ 1 trillion industry by 2015 (Nel et al. 2006).

Nanoparticles are particles that have one or more dimensions [less than or equal to] 100 nm [Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) 2005]. Because of their small size, much concern has been expressed about the potential for adverse health effects arising from the ability of nanoparticles to penetrate cell walls and the blood-brain barrier. These concerns include possible detrimental health effects during manufacture and transport as well as their fate and transport in the environment [United Kingdom Royal Society 2004; U.S. Environmental Protection Agency (U.S. EPA) 2005]. At this time there are no occupational health and safety guidelines for production and use of these nano products. This concern over lack of guidelines has resulted in a coordinated collaborative effort between several U.S. agencies--the National Institutes of Health, the National Toxicology Program headquartered at the National Institute of Environmental Health Sciences, the U.S. EPA, the Centers for Disease Control and Prevention, the National Institute for Occupational Safety and Health, and the Occupational Safety and Health Administration--and comprehensive reports by The Royal Society and the Royal Academy of Engineering of the United Kingdom (2004), a European Commission report (SCENIHR 2005), and a White paper from the U.S. EPA (2005). These efforts address several additional critical issues that include the lack of standardization of materials available for confirmatory product evaluation, monitoring in the workplace and environment, and testing procedures.

Some of the major industries using or planning to use nanotechnology manufactured goods include electronics, personal care products, and metal and ceramic manufacturers. By design, many of the nanotechnology products in development or in use contain a metal (or metalloid in the case of arsenic) (Table 1). We suggest that many of the concerns outlined above can be addressed with the approach of isotopic tracing, whereby a stable isotope of the element of interest is incorporated into the product, allowing any transfer to be easily detected using inductively coupled mass spectrometry (ICP-MS), high resolution ICP-MS, multi-collector ICP-MS, or thermal ionization MS (TIMS). This approach differs from tracing using radiolabeled metals, such as [.sup.64.Cu], which generally have a short half-life (Michalet et al. 2005)

Stable Isotope Tracing

For several decades, stable isotope tracing has been used widely in the earth sciences, such as understanding the origin of rocks and in environmental applications. …