The September 1, 2007, issue of Environmental Health Perspectives includes an article entitled “Persistent Tissue Kinetics and Redistribution of Nanoparticles, Quantum Dot 705, in Mice: ICP-MS Quantitative Assessment.”  The purpose of the study was to assess the tissue disposition and pharmacokinetics of quantum dots (QD705) in mice.  According to the article, the plasma half-life of QD705 in mice was short (18.5 hours), but analyses revealed QD705 persisted and even continued to increase in the spleen, liver, and kidney 28 days following an intravenous dose.  Considerable time-dependent redistribution from body mass to liver and kidney was apparent between 1 and 28 days post-dosing.  The recoveries at both time points were near 100%; all QD705s reside in the body.  Neither fecal nor urinary excretion of QD705 was detected appreciably in 28 days post-dosing.  Fluorescence microscopy demonstrated deposition of QD705 in the liver, spleen, and kidneys.