New York Times
March 29, 2004
Health Concerns in Nanotechnology
By BARNABY J. FEDER
uckyballs, a spherical form of carbon discovered in 1985 and an important material in the new field of nanotechnology, can cause extensive brain damage in fish, according to research presented yesterday at a national meeting of the American Chemical Society in Anaheim, Calif.
Eva Oberdörster, an environmental toxicologist at Southern Methodist University in Dallas, said the buckyballs also altered the behavior of genes in liver cells of the juvenile largemouth bass she studied.
Buckyballs are part of a group of materials called fullerenes for their structural resemblance to the geodesic domes designed by Buckminster Fuller. Synthetically produced buckyballs, along with more recently created fullerenes like carbon nanotubes, have played a major role in igniting interest in nanotechnology, the field in which researchers manipulate materials with dimensions measured in nanometers. A nanometer is a billionth of a meter - tens of thousands of times thinner than a human hair.
The new carbon molecules have been studied for numerous potential uses in advanced computer processors, lubricants, fuel cells and drug delivery systems.
But yesterday's report is the latest of several that raise questions about the potential health and environmental effects of synthetic nanoscale materials. Other researchers, including Dr. Oberdörster's father, Günter Oberdörster, a professor of environmental medicine at the University of Rochester, have shown that such particles can enter the brain. The fish studies, however, were the first to indicate destruction of lipid cells, the most common form of brain tissue.
Dr. Oberdörster of S.M.U. said that the results underscored the need to learn more about how buckyballs and other nanoscale materials are absorbed, how they might damage organisms and what levels of exposure represent hazards. But she rejected arguments made by some nanotechnology critics that the limited toxicological research to date justified a moratorium on the development and sale of the new materials.
"This is a yellow light, not a red one," Dr. Oberdörster said in a telephone interview last week.
Vicki L. Colvin, whose laboratory at Rice University's Center for Biological and Environmental Nanotechnology supplied the buckyballs used by Dr. Oberdörster, was even more cautious about the results, which have not yet been reviewed by other scientists.
Dr. Colvin said that the surface characteristics of the lab's buckyballs, which are not a form that is commercially available, needed further study. She said that they had not been coated, a process that is commonly used to limit the toxicity of such materials in applications like drug delivery.
David B. Warheit, a DuPont researcher who led a session on nanoparticles last week at the Society of Toxicology's national meeting in Baltimore and also presented a paper in Anaheim yesterday, said that numerous fundamental questions about their toxicity are beginning to be addressed. Dr. Warheit said that how nanoparticles are coated and how quickly they clump together may be more important factors in toxicity than their size.
Some companies making nanoparticles have conducted toxicology studies that might offer additional illumination. The extent of those studies is not known, and some results have not been disclosed, either for competitive reasons or because of the costs of preparing the data for publication in scientific journals.
For example, C Sixty Inc., a start-up company in Houston working on drugs and drug delivery systems based on buckyballs, said that unreported data on its coated buckyballs in zebra fish embryos and adult rodents showed toxicity levels comparable to or lower than many existing medicines.
The rodent tests indicated that C Sixty's buckyballs collect in the kidneys and liver and are excreted like other wastes after completing their function of delivering medicines, said Russell M. Lebovitz, the company's vice president for research and business development.
The zebra fish studies were conducted by a contractor; the rodent studies were done by Dr. Laura L. Dugan, an associate professor of neurology and medicine at Washington University in St. Louis, Mr. Lebovitz said. Dr. Dugan is preparing her work for submission to a scientific journal.
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