W1 PM Overview of Manufactured Nanomaterials and the Environment
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in Ballroom 1

(HAA-1117-840104) Nanotoxicology in aquatic species: Acute toxicity and effects on biotransformation enzymes.

Haasch, M¹, McClellan-Green, P^{2, 3}, Oberdorster, E^{2, 4}, ¹ The University of Mississippi, University, MS, USA² Duke Marine Laboratory, Beaufort, NC, USA³ North Carolina State University, Morehead City, NC, USA⁴ Southern Methodist University, Dallas, TX, USA

ABSTRACT- In the new science of nanotoxicology there are considerable knowledge gaps regarding the fate, transport, partitioning, bioaccumulation, biotransformation and potential for toxicity of manufactured nanoparticles. Early investigations employed THF to increase the water solubility of fullerene. THF–solubilized C60 was found to form aggregates and was designated as nano-C60 (nC60). Subsequently it was learned that C60 could be made water-soluble by a water-stir method. Acute toxicity studies (48 hr, Daphnia magna) using various concentrations of THF– and water–stirred–nC60 determined that water–stirred–nC60 was less toxic than THF–nC60 (LC₅₀ > 5 ppm compared to ∼0.8 ppm). Further investigations with water–stirred–nC60 demonstrated that uptake was rapid (∼1.3 ppm nC60/mg tissue in 1 hr at 30 ppm), that offspring production was decreased at ≥ 2.5 ppm and that there was a significant decrease in the number of offspring produced in the first brood at 5 ppm. THF–nC60 has also been shown to induce lipid peroxidation (LPO) in the brains of juvenile largemouth bass (Micropterus salmoides; Oberdörster, 2004). In order to examine this further, adult male fathead minnows (Pimephales promelas) were exposed to water–stirred nC60 (waterborne) at 0.5 ppm nC60 (n=5) in Reconstituted Hard Water (RHW) in 1L aquaria for 48 hrs. Control fish were exposed to only RHW. Determination of LPO and CYP2 family protein expression indicated that nC60 elevated LPO in the brain and gill. A significant increase in expression of both CYP2 family isozymes and peroxisomal membrane protein (PMP70) in liver was also shown through immunoblot and quantitative real–time PCR, respectively. BSA–coated SWCNT interfered with biotransformation enzyme (7–ethoxycoumarin) activity in an in vitro liver microsome assay. These studies begin to address the knowledge gaps associated with nanotoxicology and provide support for the hypothesis that the toxicity of manufactured nanoparticles is related to changes in oxidative stress. (Supported by Duke Marine Laboratory, NC and the Environmental Toxicology Research Program, National Center for Natural Products Research, The University of Mississippi, MS USA)

Key words: nanotoxicology, fullerene, single-walled carbon nanotube, biotransformation