On October 10, 2011, ACS Nano accepted an article entitled “Generation of Metal Nanoparticles from Silver and Copper Objects:  Nanoparticle Dynamics on Surfaces and Potential Sources of Nanoparticles in the Environment,” in which the authors monitor nanoparticles and their transformations under a variety of environmental conditions.  According to the authors, their studies reveal “unprecedented dynamic behavior” of silver nanoparticles on surfaces.  The authors hypothesize that nanoparticle production occurs through a process involving three stages:  (1) oxidation and dissolution of silver from the surface of the particle; (2) diffusion of silver ion across the surface in an adsorbed water layer; and (3) formation of new, smaller particles by chemical and/or photoreduction.  The authors investigated non-nanoscale sources of silver, including wire, jewelry, and eating utensils placed in contact with surfaces, and found that they also formed new nanoparticles.  According to the authors, copper objects display similar reactivity, suggesting that the phenomenon may be more general.  The authors conclude that “discovery that [silver nanoparticles and copper nanoparticles] are generated spontaneously from manmade objects implies that humans have long been in direct contact with these nanomaterials and that macroscale objects represent a potential source of incidental nanoparticles in the environment.”