Engineered nanomaterials differing in size, shape, surface area and composition are used in research, industrial, and consumer applications. Because of their unique structure and size the need exists for toxicological profiles of nanoparticles as a basis for accurate environmental risk assessments. We have begun assessing the toxicology of commercially available fluorescent semiconductor nanocrystals (Q-dots®, Quantum Dot Corp, Hayward CA), that contain toxic metals. Our results include: 1) Fluorescence of the aquatic invertebrate Cerodaphnia dubia increased significantly after a 4 hr exposure to 200 ppt nanocrystals. Changes in fluorescence were exposure and dose dependent. 2) 48-h acute toxicology endpoint assessment of these nanocrystals (using 48-h US EPA standard test protocol) found no measurable toxicity at concentrations as high as 100 ppb (measured [Cd] in 100 ppb nanocrystals was 7000 ppb). Measured Cd LC50 in 48-h laboratory exposures was 28.55 g/L. 3) Inductively coupled plasma mass spectrometry (ICP-MS) can be used to detect and measure Cd and Se in organisms exposed to these nanocrystals. These results suggest that coatings present on nanocrystals provide a protective measure from toxic metals during acute exposures. Further testing is needed to characterize their fate within aqueous ecosystems and effects of chronic exposure to these particles.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2007 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 20, 2007
Pages: 612 - 615
Industry sectors: Medical & Biotech | Personal & Home Care, Food & Agriculture
Topics: Environmental Health & Safety of Nanomaterials