R1 AM Nanotechnology Environmental and Health Impacts
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in Ballroom 1

(TEM-1117-550779) Lifecycle Effects of Bulk and Purified Carbon Nanotubes on an Estuarine Meiobenthic Copepod.

Templeton, R¹, Ferguson, P¹, Chandler, G¹, ¹ University of South Carolina

ABSTRACT- Two full life-cycle bioassays were performed using Amphiascus tenuiremis (ASTM method E-2317-04) to test the toxicity of Single Walled Carbon Nanotubes (SWCNTs). A cohort of <24hr old nauplii were tested by culturing single nauplii in individual 96-well microplate wells (n=35 nauplii/plate/treatment, 3 replicates/treatment) amended with SWCNTs in seawater. 10ppm, 1.62ppm, 972ppb, 583ppb, and 0ppb of non-purified and electrophoretically purified carbon nanotubes in 30ppt seawater were assayed. On day 20 of each bioassay, surviving adult male and female copepods were mated, pairwise. Purified/dialyzed SCWNTs showed very little toxicity in all treatments, with no significant differences in survival rates, mating success, or the number of viable offspring per mating pair across treatments (=0.05). Development was not significantly affected from the naupliar to copepodite stages nor from naupliar to adult male or female; however a significant 10% enhancement in development rate from copepodite to the adult female stage was seen in the 583ppb treatment when compared to controls (p=0.04). In contrast, bulk/dialyzed SWCNTs (containing smaller carbon nanomaterial impurities) exhibited sharply increased toxic effects with increased concentration. Relative to controls, survival rates were significantly decreased by 64% and 20% to the copepodite stage, and 80% and 20% to the adult stage for the 10ppm and 1.62ppm treatments, respectively (p<0.05). Naupliar development to the copepodite stage at 10ppm was delayed significantly by 56% compared to the control (p<0.0001). Copepodite to adult stage development was not delayed for female or male copepods at 10ppm; however significant delays of 24% for females (p=0.03) and 22% for males (p=0.03) were seen for naupliar growth to adult stages at 10ppm. These results suggest size-dependent toxicity for SWCNT based nanomaterials, with the shortest, least commercially-utilized, waste fractions resulting in increased mortality and delayed larval development. Purified SWCNTs appear non-toxic up to the environmentally unlikely 10ppm concentration.

Key words: Single Walled Carbon Nanotubes, meiobenthic copepod, toxicity, 96-well bioassay