| A Toxicologic Review of Quantum Dots: Toxicity Depends on Physicochemical and Environmental Factors Ron Hardman Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, USA Abstract
As a growing applied science, nanotechnology has considerable global socioeconomic value, and the benefits afforded by nanoscale materials and processes are expected to have significant impacts on almost all industries and all areas of society. A diverse array of engineered nanoscale products and processes have emerged [e.g., carbon nanotubes, fullerene derivatives, and quantum dots (QDs) ], with widespread applications in fields such as medicine, plastics, energy, electronics, and aerospace. With the nanotechnology economy estimated to be valued at $1 trillion by 2012, the prevalence of these materials in society will be increasing, as will the likelihood of exposures. Importantly, the vastness and novelty of the nanotechnology frontier leave many areas unexplored, or underexplored, such as the potential adverse human health effects resulting from exposure to novel nanomaterials. It is within this context that the need for understanding the potentially harmful side effects of these materials becomes clear. The reviewed literature suggests several key points: Not all QDs are alike ; engineered QDs cannot be considered a uniform group of substances. QD absorption, distribution, metabolism, excretion, and toxicity depend on multiple factors derived from both inherent physicochemical properties and environmental conditions ; QD size, charge, concentration, outer coating bioactivity (capping material and functional groups) , and oxidative, photolytic, and mechanical stability have each been implicated as determining factors in QD toxicity. Although they offer potentially invaluable societal benefits such as drug targeting and in vivo biomedical imaging, QDs may also pose risks to human health and the environment under certain conditions. Key words: environment, human health, nanomaterials, nanosized particles, nanotechnology, nanotoxicology, quantum dots, toxicology. Environ Health Perspect 114:165-172 (2006) . doi:10.1289/ehp.8284 available via http://dx.doi.org/ [Online 20 September 2005]
Address correspondence to R. Hardman, Duke University, Nicholas School of the Environment and Earth Sciences, LSRC A333, Durham, NC 27708 USA. Telephone: (919) 741-0621. Fax: (919) 684-8741. E-mail: ron.hardman@duke.edu The author declares he has no competing financial interests. Received 4 May 2005 ; accepted 19 September 2005.
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