The toxicity of silver nanoparticles (AgNPs) to green alga Pseudokirchneriella subcapitata was evaluated in standard nutrient medium (ISO 8692), lake water samples from an oligotrophic and an eutrophic lake, and in lake waters supplemented with the standard nutrient medium. Prior to toxicity testing the agglomeration of polyvinylpyrrolidone (PVP) and starch-coated AgNPs was studied in each test medium. Agglomeration was studied by determining the hydrodynamic diameter (HDD). The HDDs for the PVP- and starch-capped AgNP dispersions in deionized water were 40 and 175 nm respectively, indicating the presence of agglomerates. The HDDs of AgNPs remained stable throughout the exposure time in all media used for the toxicity tests. The algae growth inhibition test was performed as a microplate modification of the ISO method using fluorescence detection. The effect of concentration at a 50% inhibition value for PVPcoated AgNPs in standard medium was 115 ± 3 μg/L, and for starchcoated AgNPs 51 ± 32 μg/L. The eutrophic freshwater conditions suppressed the toxicity of the PVP- coated AgNPs, but not the starchcoated NPs. This finding emphasizes the importance of using different AgNPs and natural waters in assessing the environmental risks of silver nanoparticles.
 S.N. Luoma. Silver nanotechnologies and the environment:
old problems or new challenges. Project on Emerging
Nanotechnologies, 15 (2008).
 B. Naumann, M. Eberius, K. Appenroth. Growth rate based
dose-response relationships and EC-values of ten heavy
metals using the duckweed growth inhibition test (ISO
20079) with Lemna minor L. clone St. J. Plant. Phys., 164,
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.