Nanotechnology, a science devoted to engineering things that are unimaginably small, may pose a health hazard and should be investigated further, warns a University of Rochester scientist and worldwide expert in the field, who received a $5.5 million grant to conduct such research. Günter Oberdörster, Ph.D., professor of Toxicology in Environmental Medicine and director of the university's EPA Particulate Matter Center, has already completed one study showing that inhaled nano-sized particles accumulate in the nasal cavities, lungs and brains of rats.

Scientists speculate this buildup could lead to harmful inflammation and the risk of brain damage or central nervous system disorders. Oberdörster's study is scheduled to appear in the May 2004 journal Inhalation Toxicology, and is receiving widespread attention in the scientific community; it was cited at an international nanotechnology/health conference earlier this year in England by the Institute of Physics. "I'm not advocating that we stop using nanotechnology, but I do believe we should continue to look for adverse health effects," says Oberdörster, who also leads the UR division of Respiratory Biology and Toxicology. "

Sixty years ago scientists showed that in primates, nano-sized particles traveled along nerves from the nose and settled into the brain. But this has mostly been forgotten. The difference today is that more nano-particles exist, and the technology is moving forward to find additional uses for them – and yet we do not have answers to important questions of the possible health impact." Backed by $600 million in recent federal funding and the support of President Bush, nanotechnology is a rising industry in the United States. Japan, Taiwan and other countries are also racing to produce nanomaterials, which can be applied to electronics, optics, medical devices and other industries.

The technology evolved when scientists found ways to manipulate carbon, zinc and gold molecules into microscopic clusters that could be useful in building almost anything ultra-small. Medical applications under development include using nanoparticles as drug-delivery systems, or as a super-advanced type of radiation therapy that could zap tumors with heat-seeking missile precision. But some scientists are concerned the industry is moving too fast. The U.S. Department of Defense awarded to grant to Oberdörster and colleagues, to develop a model that would predict the toxicity of certain nanoparticles.

Oberdörster is leading the five-year study, employing a multidisciplinary team from 10 departments at three universities (UR, University of Minnesota, University of Washington at St. Louis.) They plan to test a hypothesis that the chemical characteristics of nanoparticles determine how they will ultimately interact with human or animal cells. A negative cellular response may indicate impaired function of the central nervous system, they propose. In previous studies, Oberdörster showed that nano-sized particles depositing in the nose of rats traveled into the olfactory bulb. At this point the team is not entirely opposed to nanotechnology, Oberdörster explains.

In fact, researchers hope to work with the industry, as well as with the American and Canadian governments, to seek solutions if problems arise. Another goal is to develop an educational program so that future engineers and scientists will understand the health consequences of nanotechnology. For decades Oberdörster has studied how the body interacts with ambient ultrafine particles, including automotive and power plant emissions and dust from the World Trade Center disaster. What's different about nanotechnology is that these particles are man-made into a well-defined size, down to a billionth of a meter, and appear to seep all the way into the mitochondria, or energy source, of living cells.

"We must consider many different issues before we come to a judgment on risk," he says. "Foremost is an assessment of potential human and environmental exposure by different routes: inhalation, ingestion, dermal. Then, what is their fate in the organism? And what are the risks of cumulative effects, given that these particles are being mass produced? At this point we're trying to balance the tremendous opportunity that nanotechnology presents with any potential harm."