Are Nanoparticles Unsafe?

Nanoparticles don't need to come into actual contact with human DNA in order to affect them, according to new research carried out by British scientists. Does this mean our miniature future is more dangerous than first thought?

The Guardian reports that scientists from the University of Bristol placed cobalt-chromium nanoparticles on one side of a cellular barrier specifically grown for the experiment, with human fibroblast cells on the other side of the barrier. Despite the nanoparticles not actually coming into contact with the fibroblasts, the fibroblast DNA was, on average, "10 times more damaged" than under control conditions as a result of the experiment; according to Patrick Case, who led the tests:

When we measured the damage on the other side of the barrier, to our great surprise, not only did we see damage on the other side of the barrier but we saw as much damage as if we'd not had the barrier at all and had put the materials in contact with the cells underneath.

The results raise questions not only about how damaging nanotechnology may be in practice, but also about the validity of the experiment. In addition to being unsure how the test results would transfer to a human body, Case admitted that the tests also used an amount of nanoparticles thousands of times higher than anyone is likely to come into contact with in reality:

We used high doses of them because we wanted to make sure that the dose we used would cause damage to cells if the cells were exposed.

So what we're left with is the possibility that nanoparticles may be damaging to human DNA, and that they also don't need to come into physical contact with the DNA in order to damage them... But we don't know for sure. Am I the only one not comforted by this?

Nanoparticles could damage DNA at a distance, study suggests [Guardian.co.uk]