Nanoparticles have been a key part of numerous recent technological advances. Biofuels, solar cells, medical imaging systems and even sunscreen - there's virtually no field of science or technology that they couldn't potentially transform. There are concerns however, about the risks posed by the countless tiny particles of materials such as silver, gold and titanium dioxide that are now entering our environment and our bodies, but a recent University of Oregon study suggests that if not completely harmless, nanoparticles are at least nothing new. In fact, it states, humans have been exposed to them for millennia.

Using transmission electron microscopes, University of Oregon chemists captured what they claim are never-before-seen images of naturally-occurring metal nanoparticles, formed when silver items such as wire, jewelry and cutlery come into contact with other surfaces. When deposited and observed on electron microscope slides, these particles were seen to change in size, shape and population within just a few hours. These changes were particularly pronounced when the nanoparticles were exposed to humid air, water and light.

The scientists have concluded two things based on their observations.

First of all, they believe that the potential dangers posed by different types of nanoparticles should not be determined based on how small they are. While larger particles initially may not be as invasive as smaller ones, the study indicates that those larger particles can and will break down and multiply.

Secondly, the study suggests that humans have been in the presence of nanoparticles at least since our species first started processing iron ore - they have been transferred to our skin from bracelets, and dropped into our mouths from forks and spoons. "The generation of nanoparticles from objects that humans have contacted for millennia suggests that humans have been exposed to these nanoparticles throughout time," stated chemist James E. Hutchison, who co-authored a paper on the research. "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."

What isn't clear, however, is how many more nanoparticles are currently entering our environment, now that we're mass-producing them. It could perhaps be countered that comparing the amount of particles shed by things like cutlery to the amount now present in modern technology, is equivalent to comparing the earth's natural background radiation to the levels now present at Fukushima.

We look forward to hearing your thoughts on the topic.

The University of Oregon paper was recently published in the journal ACS Nano.