This is the stark warning of Gunter Oberdorster, an acknowledged expert in the field who is professor of Toxicology in Environmental Medicine at the University of Rochester in the US.
Oberdorster has already completed one study showing that inhaled nano-sized particles accumulate in the nasal cavities, lungs and brains of rats, raising concerns that this build-up could lead to harmful inflammation and a risk of brain damage or other central nervous system disorders.
"I'm not advocating that we stop using nanotechnology, but I do believe we should continue to look for adverse health effects," said Oberdorster. His comments come at a time when countries in Europe have started to increase their investment in nanotechnology research and to debate its role in society. For example, last July, the UK earmarked £90 million (€131m) to help industry develop commercial uses for nanotechnology.
"60 years ago scientists showed that in primates, nano-sized particles travelled 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," he noted.
The US has earmarked a massive €.1 billion in federal funding overthe next four years to ensure that the country is a major player in the emerging nanotechnology industry, while Japan, Taiwan and other countries are also racing to produce nanomaterials.
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 that can deliver drugs to specific regions of the body, new materials for medical devices and as a way to target radiation therapy accurately to tumours.
The US Department of Defense awarded to $5.5 million grant to Oberdorster to develop a model that would predict the toxicity of certain nanoparticles.The five-year project will 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, reported in Nature in January, Oberdorster showed that nano-sized particles depositing in the nose of rats travelled into the olfactory bulb.
He has studying how the body interacts with ambient ultrafine particles for decades, focusing on areas such as automotive and power plant emissions and dust from the World Trade Centre disaster. But he feels nanotechnology represents an even greater risk because the size of the particles - down to a billionth of a meter - appear to seep all the way into the structures of human cells, including the mitochondria (the organelles that provide energy for cell functioning).
"We must consider many different issues before we come to a judgment on risk," he said. For example, more research is needed on human and environmental exposure by different routes (inhalation, ingestion, dermal), the fate of the particles in the organism and the risks of cumulative effects, given that these particles will be mass produced.
"At this point we're trying to balance the tremendous opportunity that nanotechnology presents with any potential harm," said Oberdorster.