ANAHEIM, CALIFORNIA--Nanotechnology is among the hottest fields in science. But controversy is on the rise as critics are calling for bans on research until nanomaterials can be shown to be safe. A study reported here 28 March at the American Chemical Society meeting is likely to fan those flames. Toxicologists reported that buckyballs, a spherical form of carbon, can cause brain damage in fish--the first indication that nanomaterials could pose a threat to aquatic life. Other experts caution that the new results don't definitively show that buckyballs are to blame.
Nanomaterials are prized by researchers because their small size gives them electrical and optical behaviors not found in their bulkier counterparts. But those same properties could alter the way they act on biological systems as well. Last year two research teams reported preliminary evidence that carbon nanotubes can damage lung tissue in rats.
The new work adds to that concern. Buckyballs are not normally soluble in water, so they ought to end up safely buried in sediment. But Vicki Colvin, a chemist at Rice University in Houston, Texas, found that buckyballs can cluster into tiny, soluble crystals that aquatic organisms could absorb. Colvin sent a sample to Eva Oberdörster, an environmental toxicologist at Southern Methodist University (SMU) in Dallas. She added the sample at .5 parts per million to a tank holding nine largemouth bass. After 48 hours, the animals developed significant brain damage--17 times more than that seen in nine unexposed animals, Oberdörster reported. Although it's unclear just how the damage occurs, one possibility is that the buckyball nanocrystals enter the brain via olfactory neurons, a route traveled by other small particles.
The new work is "very good," says Barbara Karn, who heads nanotechnology research for the Environmental Protection Agency. But she and Colvin note that far more work must be done to pin down the toxicology of buckyballs and other nanomaterials. Colvin points out that the SMU researchers didn't isolate nanocrystals from the brains of fish to show that they were in fact the cause of the damage. Although buckyballs are not now in the environment, a Japanese firm is building a plant to mass produce them for electronic applications.