Assessment of nanosilver toxicity during zebrafish (Danio rerio) development

• The toxicity of silver nanoparticles was compared to dissolved silver in zebrafish embryos.
• Dissolved silver was more toxic than silver nanoparticles.
• Both silver forms induced mortality and delayed hatching.
• Both silver forms generated ROS and reduced glutathione levels.

Nanomaterials (NMs) including silver nanoparticles (AgNPs) are incorporated into an increasing number of consumer and medical products. However, the potential toxicity of AgNPs to aquatic organisms is largely unknown. This study characterizes the effects of AgNPs on zebrafish (Danio rerio) development. The effects of silver ions (Ag+) and AgNPs were examined at equivalent Ag concentrations, which ranged from 0.03 to 1.55 μg mL−1 total Ag. The Ag+ was more toxic than AgNPs but both lead to death and delayed hatching in surviving embryos. Both silver types depleted glutathione levels but generally did not affect antioxidant enzymes activities. In addition to silver some of the embryos were also exposed to cysteine, which generally reduced the toxicity of both silver types. This study demonstrates that AgNPs and Ag+ are capable of inducing toxicity in zebrafish embryos including the induction of oxidative stress.