Eat up your buckyballs (for your liver’s sake)

The discovery by Eva Oberdorster that the molecule C60, or buckminster fullerene, caused brain damage in large mouthed bass received huge publicity when it was first reported, (see here for a relatively level-headed account). This work has now become one of the main underpinning texts of the belief that there is something uniquely dangerous about nanomaterials. It’s interesting, though perhaps not surprising, that a recent article in the American Chemical Society journal Nano Letters, which reaches an exactly opposite conclusion, (abstract, subscription required for full article) has received no publicity at all.

In this work, from Fathi Moussa’s group in the Department of Pharmacy in Université Paris XI, it is shown that not only did C60 not have a toxic effect on the rats and mice it was tested on; it also protected rat’s livers from the toxic effects of carbon tetrachloride, an effect ascribed to C60’s powerful anti-oxidant properties. The paper is not reticent in its criticism of the earlier work; it ascribes the apparent toxic effects previously observed to the fact that the C60 was prepared in an organic solvent, THF, which was not completely removed when a water-suspension of C60 was prepared. In short, it was the toxic effects of THF that were affecting the unfortunate fish, not those of C60. The tone of these comments is suprisingly caustic for a peer reviewed paper, and it finishes with a note of magnificent Gallic sarcasm. Referring to reports that naturally occurring fullerenes (presumably from the soot from forest fires) have been discovered in fossil dinosaur eggs, the authors ask “we feel that it cannot be said that the C60 discovered in dinosaur eggs was the origin of the mass extinction of these animals, or was it?”

I should stress that I’m not advocating that Soft Machines readers should immediately consume a large quantity of C60 and then start abusing solvents, nor should we now assume that fullerenes are entirely safe and without potential environmental problems. But there are a couple of lessons we should draw from this. Firstly, toxicology is not necessarily easy to get right. But perhaps the most important lesson is that learning about science from press releases is very misleading. What appear to be the big breakthroughs at the time get lots of coverage, but the follow-up work, which can modify or even completely contradict the initial big story, barely gets noticed.