Researchers who study the impact of nanotechnology on people, animals and the environment struggle with many issues, as outlined in this article. One new debate is: How much of a particular nanoscale material should they use to test for safety? In many laboratory studies, the test medium is hit with large amounts of the nanomaterial being tested – at times because nanoparticles are so tough to measure that testing with small amounts is difficult – at others, because using large amounts might help a researcher have an inkling about what would happen over the course of many years. The question is how much is too much, and whether such studies can be translated into the real world. Mark Wiesner, a professor at Duke University and the director of the Center for Environmental Impact of NanoTechnology, United States, says, “Sometimes, you have to do that [use large amounts], because there’s nothing else that you can do,” but, he adds, “you can go to extremes, where you’re working with very high concentrations. I’m just not sure what we necessarily learn from that.” Wiesner said an even tougher problem is finding the best way to measure nanoparticles – should it be by mass, surface area, or by the number of particles? “Each one could be relevant,” he said. Another, broader, question, adds Wiesner, is where are the silver nanoparticles in sewage sludge coming from, exactly? Are they released from your neighbor’s anti-stink socks, or from some other source? And the carbon nanotubes in the air, were they released from a manufacturer, or gasoline exhaust? Wiesner asks: “Have we been—and I think the answer is yes—submerged in nanoparticles from time immemorial? It might be irrelevant. We don’t know. It might also be very important.”
http://www.newhavenindependent.org/index.php/archives/entry/nano_testing/id_36688