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nanotimes News in Brief

Regulations // Environmental Health Concerns Should not be Regulated Based upon size

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sing a new approach developed at UO‘s Mate- rials Science Institute and the Safer Nanoma-

terials and Nanomanufacturing Initiative (SNNI, USA), in collaboration with UO technology spinoff Dune Sciences Inc. that allows for the direct obser- vation of microscopic changes in nanoparticles over time, researchers found that silver nanoparticles deposited on the surface of their SMART Grids elec- tron microscope slides began to transform in size, shape and particle populations within a few hours, especially when exposed to humid air, water and light. Similar dynamic behavior and new nanoparticle formation was observed when the study was exten- ded to look at macro-sized silver objects such as wire or jewelry.

“Our findings show that nanoparticle ‘size‘ may not be static, especially when particles are on surfaces. For this reason, we believe that environmental health and safety concerns should not be defined – or regulated – based upon size,” said James E. Hutchison, who holds the Lokey-Harrington Chair in Chemistry. “In addition, the generation of nanopar- ticles from objects that humans have contacted for millennia suggests that humans have been exposed to these nanoparticles throughout time. Rather than raise concern, I think this suggests that we would have already linked exposure to these materials to health hazards if there were any.”

Because copper behaved similarly, the researchers theorize that their findings represent a general phe- nomenon for metals readily oxidized and reduced under certain environmental conditions.

“These findings,” they wrote, “challenge conventio- nal thinking about nanoparticle reactivity and imply that the production of new nanoparticles is an intrin- sic property of the material that is now strongly size dependent.”

While not addressed directly, Hutchison said, the naturally occurring and spontaneous activity seen in the research suggests that exposure to toxic metal ions, for example, might not be reduced simply by using larger particles in the presence of living tissue or organisms.

Richard D. Glover, John M. Miller, and James E. Hutchison: Generation of Metal Nanoparticles from Silver and Copper Objects: Nanoparticle Dynamics on Surfaces and Poten- tial Sources of Nanoparticles in the Environment, In: ACS Nano ASAP, October 10, 2011, DOI:10.1021/nn203131: http://dx.doi.org/10.1021/nn203131

http://chemistry.uoregon.edu/fac.html?hutchison http://pages.uoregon.edu/msiuo/ http://pages.uoregon.edu/chem/

11-10 :: October 2011