Risk Assessment of the Carbon Nanotube Group.

This study assessed the health risks via inhalation and derived the occupational exposure limit (OEL) for the carbon nanotube (CNT) group rather than individual CNT material. We devised two methods: the integration of the intratracheal instillation (IT) data with the inhalation (IH) data, and the "biaxial approach." A four-week IH test and IT test were performed in rats exposed to representative materials to obtain the no observed adverse effect level, based on which the OEL was derived.

Reproductive and developmental toxicity studies of manufactured nanomaterials.

This paper reviews studies in vivo and in vitro on the reproductive and developmental toxicity of manufactured nanomaterials including metallic and metal oxide-based particles, fullerenes (C(60)), carbon black (CB), and luminescent particles. Studies in vivo showed increased allergic susceptibility in offspring of mouse dams intranasally insufflated with respirable-size titanium dioxide (TiO(2)), adverse effects on spermatogenesis and histopathological changes in the testes and changes in gene expression in the brain of mouse offspring after maternal subcutaneous injection of TiO(2) nanoparticles, transfer to rat fetuses of radiolabeled gold nanoparticles and C(60) after maternal intravenous injection, death and morphological abnormalities in mouse embryos after maternal intraperitoneal injection of C(60), and adverse effects on spermatogenesis in mouse offspring after maternal intratracheal instillation of CB nanoparticles. Studies in vitro revealed that TiO(2) and CB nanoparticles affected the viability of mouse Leydig cells, that gold nanoparticles reduced the motility of human sperm, that silver, aluminum, and molybdenum trioxide were toxic to mouse spermatogonia stem cells, that silica nanoparticles and C(60) inhibited the differentiation of mouse embryonic stem cells and midbrain cells, respectively, and that cadmium selenium-core quantum dots inhibited pre- and postimplantation development of mouse embryos.