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Single-walled carbon nanotubes: skin exposures.
Murray-AR; Kisin-E; Leonard-SS; Young-SH; Kommineni-C; Kagan-VE; Castranova-V; Shvedova-AA
Toxicologist 2009 Mar; 108(1):458
Nanotechnology is a newly developing field resulting in the development of unique materials with a variety of applications from electronics to engineered tissue. SWCNT are of the most interest because of their unique mechanical and electrical properties which result from their fibrous shape and small size. The most common technique for manufacturing SWCNT relies on the use of iron as a transition metal catalyst and can result in the presence of up to 30% metal catalyst in raw SWCNT. The low density of SWCNT may lead to inhalation as well as deposition on exposed skin, which provide routes of exposure that are important to consider when evaluating toxicity. We hypothesized that SWCNT are toxic to the skin, and this toxicity is dependent on the ability of SWCNT to interact with the skin and initiate oxidative stress, and the induction of transcription factors leading to inflammation. To test this hypothesis, the effects of SWCNT were assessed both in vitro and in vivo. Engineered skin exposed to SWCNT showed increased epidermal thickness and accumulation and activation of dermal fibroblasts, which resulted in increased collagen as well as release of pro-inflammatory cytokines. Exposure of JB6 cells to unpurified SWCNT resulted in the production hydroxyl radicals as detected by ESR and caused a significant dose-dependent activation of AP-1 and NFkB, while partially-purified SWCNT activated only NFkB. Topical exposure of SKH-1 mice (5 days, 40, 80, 160 mu g/mouse/day) to SWCNT caused oxidative stress, depletion of GSH, oxidation of protein thiols and carbonyls, elevated MPO activity, and an increase of dermal cell numbers resulting in skin thickening. Altogether, these data indicated that topical exposure to unpurified SWCNT induced free radical generation, oxidative stress, and inflammation, leading to dermal toxicity.
Biological-effects; Biological-factors; Cellular-reactions; Cell-biology; Cytology; Exposure-assessment; Exposure-levels; Exposure-methods; Irritants; Inhalation-studies; Laboratory-animals; Lung-cells; Lung-disorders; Lung-irritants; Microscopic-analysis; Microscopy; Oxidative-processes; Particle-aerodynamics; Particulate-dust; Particulates; Respiratory-irritants; Respiratory-system-disorders; Risk-factors; Skin; Skin-absorption; Skin-exposure; Skin-irritants; Toxic-effects; Nanotechnology
Issue of Publication
The Toxicologist. Society of Toxicology 48th Annual Meeting and ToxExpo, March 15-19, 2009, Baltimore, Maryland
University of Pittsburgh at Pittsburgh
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