Web Release Date: June 22,
Life-Cycle Effects of Single-Walled
Carbon Nanotubes (SWNTs) on an
Estuarine Meiobenthic Copepod
and
Marine Science Program, Department of Chemistry and Biochemistry, and Department of Environmental Health Sciences, University of South Carolina, Columbia, South Carolina 29208
Received for review February 20, 2006
Revised manuscript received May 17, 2006
Accepted May 22, 2006
Abstract:
Single-walled carbon nanotubes (SWNT) are finding increasing use in consumer electronics and structural composites. These nanomaterials and their manufacturing byproducts may eventually reach estuarine systems through wastewater discharge. The acute and chronic toxicity of SWNTs were evaluated using full life-cycle bioassays with the estuarine copepod Amphiascus tenuiremis (ASTM method E-2317-04). A synchronous cohort of naupliar larvae was assayed by culturing individual larvae to adulthood in individual 96-well microplate wells amended with SWNTs in seawater. Copepods were exposed to "as prepared" (AP) SWNTs, electrophoretically purified SWNTs, or a fluorescent fraction of nanocarbon synthetic byproducts. Copepods ingesting purified SWNTs showed no significant effects on mortality, development, and reproduction across exposures (p<0.05). In contrast, exposure to the more complex AP-SWNT mixture significantly increased life-cycle mortality, reduced fertilization rates, and reduced molting success in the highest exposure (10 mg·L-1) (p<0.05). Exposure to small fluorescent nanocarbon byproducts caused significantly increased life-cycle mortality at 10 mg·L-1 (p<0.05). The fluorescent nanocarbon fraction also caused significant reduction in life-cycle molting success for all exposures (p<0.05). These results suggest size-dependent toxicity of SWNT-based nanomaterials, with the smallest synthetic byproduct fractions causing increased mortality and delayed copepod development over the concentration ranges tested.
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