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Effects of Silver Nanoparticles on Japanese Medaka (Oryzias latipes) and Daphnia magna
Citation:
HOHEISEL, S., A. A. BRENNAN, S. A. DIAMOND, AND D. R. MOUNT. Effects of Silver Nanoparticles on Japanese Medaka (Oryzias latipes) and Daphnia magna. Presented at 30th Annual Meeting of SETAC North America, New Orleans, LA, November 19 - 23, 2009.
Impact/Purpose:
To show that medaka larvae had fairly low acute sensitivity to nano-silver, with LC50 values in the range of 10-30 mg/L total silver. To allow inferences to be drawn about the route of exposure and mechanism of toxicity for silver nanoparticles.
Description:
The introduction of nanoparticles into a variety of consumer products has raised questions about the potential effects of environmental release, and particularly whether the presence of materials at the nano-scale creates potential risks not associated with the bulk materials. Citrate-capped silver nanoparticles were prepared de novo, and characterized for particle size distribution using dynamic light scattering. Toxicity studies were conducted to determine the lethal and sublethal toxicity of these particles to Japanese medaka and the cladoceran Daphnia magna. In addition to determining effect concentrations, these studies evaluated the likelihood that the observed toxicity was attributable to nanoparticles themselves, or to silver ions associated with nano-silver synthesis and/or released from silver nanoparticles. Initial studies showed that medaka larvae had fairly low acute sensitivity to nano-silver, with LC50 values in the range of 10-30 mg/L total silver. The addition of sodium thiosulfate reduced or eliminated this toxicity, suggesting that at least some of the observed toxicity was attributable to ionic silver, as thiosulfate is known to chelate ionic silver and reduce its bioavailability. Additional tests compared the relative effects of ionic silver and silver nanoparticles on D. magna reproduction as well as larval growth and development of medaka. Comparisons of the sensitivity of fish and daphnids allow inferences to be drawn about the route of exposure and mechanism of toxicity for silver nanoparticles.