In just the past few years, nanotechnology has brought technological advances in almost every field imaginable - patches that regenerate heart tissue, water-powered batteries and better biofuels are just a few examples. As with just about any new technology, however, concerns have been raised regarding its safety. We've never experienced anything quite like it before, so how far should we trust it? According to a recent study conducted at the University of Plymouth, the answer to that question might be "Not very far." In tests on rainbow trout, titanium oxide nanoparticles were found to cause damage to the brain and other parts of the central nervous system.

Titanium oxide nanoparticles are used in a number of applications including paints, vitamins, personal care products such as sunscreen and cosmetics, and possibly soon in food products. After being subjected to these nanoparticles, the trout developed vacuoles (holes) in parts of their brains, and some of their brain cells died. Although past tests on cell cultures and other in vitro systems have suggested possible harmful effects of nanoparticles, this is reportedly the first time that such effects have been confirmed in a live vertebrate.

So far, it isn't clear whether or not the nanoparticles actually entered the fishes' brains, or if the holes were caused by their presence elsewhere in the trouts' systems. There is currently no word on how many fish were tested, or under what conditions.

"It is worrying that the effects on the fish brain caused by these nanoparticles have some parallels with other substances like mercury poisoning, and one concern is that the materials may bioaccumulate and present a progressive or persistent hazard to wildlife and to humans", said the University of Plymouth's Prof. Richard Handy, who led the research.