Body Distribution of Inhaled Fluorescent Magnetic Nanoparticles in the Mice: Jung‐Taek Kwon, et al. Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Korea—Reducing the particle size of materials is an efficient and reliable tool for improving the bioavailability of a gene or drug delivery system. In fact, nanotechnology helps in overcoming the limitations of size and can change the outlook of the world regarding science. However, a potential harmful effect of nanomaterial on workers manufacturing nanoparticles is expected in the workplace and the lack of information regarding body distribution of inhaled nanoparticles may pose serious problem. In this study, we addressed this question by studying the body distribution of inhaled nanoparticles in mice using approximately 50‐nm fluorescent magnetic nanoparticles (FMNPs) as a model of nanoparticles through nose‐only exposure chamber system developed by our group. Scanning mobility particle sizer (SMPS) analysis revealed that the mice were exposed to FMNPs with a total particle number of 4.89 × 10⁵± 2.37 × 10⁴/cm³(low concentration) and 9.34 × 10⁵± 5.11 × 10⁴/cm³(high concentration) for 4 wk (4 h/d, 5 d/wk). The body distribution of FMNPs was examined by magnetic resonance imaging (MRI) and Confocal Laser Scanning Microscope (CLSM) analysis. FMNPs were distributed in various organs, including the liver, testis, spleen, lung and brain. T2‐weighted spin‐echo MR images showed that FMNPs could penetrate the blood‐brain‐barrier (BBB). Application of nanotechnologies should not produce adverse effects on human health and the environment. To predict and prevent the potential toxicity of nanomaterials, therefore, extensive studies should be performed under different routes of exposure with different sizes and shapes of nanomaterials.

Understanding reproductive development effects and transferable properties to next generation of zinc oxide nanoparticles is necessary for prevention of its potential risks. To accomplish this, rats were exposed to zinc oxide nanomaterials (500 mg/kg bw) of less than 100 nm beginning 2 weeks before mating to postnatal day 4. In addition, body distribution of zinc concentration was evaluated in dams and offspring. Rat treated with nano-zinc oxide showed reduced number of born/live pups, decreased body weights of pups and increased fetal resorption. Zinc oxide nanomaterials were also distributed to organs such as mammary tissue of dams and liver and kidney of pups. These results indicate that zinc oxide nanoparticles-exposure before and during pregnancy and lactation could pose health risks to pregnant women and their fetus.