1 Modeling the Toxic Effects of Silver Nanoparticles under Varying Environmental Conditions

Due to the abundance of silver nanoparticles in the nanotechnology consumer market, "nanosilver" has become a major concern in the scientific community. This investigation attempts to model and quantify the toxicity of nanosilver under a range of environmental conditions and to measure the reliability of a nanosilver consumer product for consumer and environmental safety. In Phases I and II of this investigation, a novel, high-throughput bacterial toxicity assay was developed to quantify the toxicity of nanosilver, defined as the percentage of cells that died in excess of that due to the natural death of cells. Phase III investigated the assertion that silver nanoparticles are more reliable and less environmentally hazardous than commonly used antimicrobial agents, such as silver ions. The bacterial toxicity assay was applied to the filtered waters of a model nanosilver water filtration system and showed that nanosilver passed through a 0.45-micron filter so that filtered water may contain these particles. This would allow them to exert their toxic effects on the aquatic environment. This investigation demonstrated three essential concepts. First, the novel bacterial toxicity assay technique provided a reliable, reproducible estimate of the potential toxicity of silver nanoparticles. Second, silver nanoparticles induced significantly greater toxic effects than silver ions. Finally, the toxicity assay substantiated the efficacy of silver nanoparticles, but questioned the reliability of nanosilver consumer products for preventing nanosilver from entering the aquatic environment