In a study carried out on rats, U.S. researchers have shown that carbon nanoparticles can move inside the brain after being inhaled, and also move from the lungs into the bloodstream. Both Nature and the Guardian publish interesting stories about this potential new danger to our health.
Let's start with Nature.
Günter Oberdörster of the University of Rochester in New York and colleagues tracked the progress of carbon particles that were only 35 nanometres in diameter and had been inhaled by rats. In the olfactory bulb -- an area of the brain that deals with smell -- nanoparticles were detected a day after inhalation, and levels continued to rise until the experiment ended after seven days.
"These are the first data to show this," says Ken Donaldson, a toxicologist at the University of Edinburgh, UK. "I would never have thought of looking for inhaled nanoparticles in the brain."
Here is a rendering of some of these nanoparticles (Credit: National Institute of Advanced Industrial Science and Technology).
Now, let's turn to the Guardian and its article, "Research on tiny particles could damage brain, scientists warn."
"It's too early to be alarmed, because we don't yet know what the particles might do in humans. We shouldn't stop working with them, we should just look for what adverse effects these particles might cause," said Oberdorster. The report is due to appear in the journal Inhalation Toxicology.
"This is the first documented evidence that an innocent particle like carbon, if it's small enough, can find its way into the brain," said Professor Ken Donaldson, a toxicologist at Edinburgh University. "The worry would be if the nanotechnology business designs nanoparticles which are fundamentally different from the ones which we are already exposed to, and seem to cope with reasonably well. If very different nanoparticles are manufactured, there's a concern that they might have a different effect in the body."
Nature is also concerned.
Little is known about what effect nanoparticles will have when they reach the brain. The toxicity of the nanoparticles that are currently being used to build prototype nanosized electronic circuits -- such as carbon nanotubes, which are produced in labs around the world -- has not been thoroughly assessed.
But Donaldson says that there is a growing feeling that other nanoparticles, such as those produced by diesel exhausts, may be damaging to some parts of our body. He estimates that people in cities take in about 25 million nanoparticles with every breath. These particles are believed to increase respiratory and cardiac problems, probably by triggering an inflammatory reaction in the lungs.
Now, more experiments are needed to determine how nanoparticles can enter our brains. In the mean time, let's hope that nanotechnology research will continue and will not be harmed by a moratorium.
Sources: Jim Giles, Nature, January 9, 2004; Ian Sample, The Guardian, January 9, 2004