Nanoparticles as sources of inorganic water pollutants

The occurrence and fate of synthetic and natural inorganic nanoparticles in surface and groundwater water are virtually unknown. Initially viewed as a means for remediation of water contamination, engineered nanoparticles are detected in the aquatic environment in an increasing number of settings, with only a handful of studies focusing on their chemical and physical transformation. Little research has been directed at nanoparticle toxicity to nontarget organisms as well as more subtle human health effects from exposure. Because metal nanoparticles have significantly different chemical properties from dissolved and microcrystalline analogs, they often have different biological effects than dissolved and mineral forms of the same element. With a growing list of sources and uses for engineered nanoparticles comes a growing level of uncertainty about environmental risks from their release into the environment. For example, exposure to cerium-oxide nanoparticles can impart measurable toxicological effects to fish and plants, while gold and silver nanoparticles have little effect on the same organisms. The ubiquitous occurrence of natural inorganic nanoparticles indicates that there is an urgent need for new methods to characterize their occurrence as inorganic pollutants so that we have a better understanding of their fate and potential human health effects.