Differentiation of the toxicities of silver nanoparticles and silver ions to the Japanese medaka (Oryzias latipes) and the cladoceran Daphnia magna.

Silver nanoparticles (AgNPs) are increasingly used in various fields. However, little is known about the environmental effects of widespread use of products containing AgNPs. The objective of this study was to determine the ecotoxicity caused by AgNPs. The 48-h effective concentration 50 (EC(50)) values for Daphnia magna of suspensions of 60 nm and 300 nm AgNPs were 1.0 (95% confidence interval [CI] = 0.1-1.3) and 1.4 (95% CI = 0.3-2.1) μg Ag/l, respectively. The 96 h LC(50) values for Oryzias latipes of 60 nm and 300 nm AgNP suspensions were 28 (95% CI = 23-34) and 67 (95% CI = 45-108) μg Ag/l, respectively. To show that toxicity is caused only by Ag(+) and not by AgNPs, Ag(+) was adsorbed onto the synthesized sorbents packed in a column and D. magna was exposed to the column-passed-300 nm AgNP suspensions. There was no acute toxicity with the AgNP suspensions not containing Ag(+).