Joined: 16 Mar 2004
|Posted: Tue Apr 03, 2007 10:35 am Post subject: Nanotech fears may be 'overblown'
|Nanotech fears may be 'overblown'
by Judy Skatssoon
Fears about nanotechnology may be overblown, says an Australian expert in toxicology and environmental health.
Monash University's Professor Brian Priestly, director of the Australian Centre for Human Health Risk Assessment, says we need to put fears about the potential health risks of nanoparticles into perspective.
Priestly was among a number of nanotech specialists who spoke about nanotoxicology at the Australian Health and Medical Research Congress in Melbourne this week.
"I'm not saying that we don't have knowledge gaps that we have to fill," he says. "But some of the statements that are being made I think are extreme."
The federal government is expected to release a national strategy on nanotechnology in the coming months and is considering whether an independent regulator should be established to oversee this rapidly advancing field.
Priestly says it's unlikely that members of the general public will be exposed to nanoparticles.
"What we have to ask is what are the chances that we will be exposed to these very fine manufactured nanoparticles, because risk is really a function of toxicity and exposure," he says.
"These things may have slightly higher grades of toxicity than larger particles but a lot depends upon whether we're exposed to them and how we're exposed to them.
"If they get into the air and we inhale them, yeah, they're likely to present the same sorts of risks we have with other types of air pollution of very fine particles."
He also says the majority of nanoparticles will be safe because they're fixed in surface coatings.
Dr Kelly BéruBé, a lecturer in cell biology at Cardiff University in Wales, has been studying nanosized products of combustion like soot and coal ash as a model for engineered nanoparticles.
She says human have been exposed to these particles for as long as we have been burning things, and it's known they can cause inflammatory responses and cardiac problems.
She says these are the sorts of particles we should be worried about, rather than engineered nanoparticles.
"These are the ones that everybody's exposed to every day. It's highly unlikely that the average person like you or I is going to be exposed to any of these engineered ones," she says.
Uses of nanoparticles
Nanotechnoloy involves the manipulation of atoms and molecules for uses in medicine, research, computing and the creation of new types of materials and surfaces.
Nanoparticles are already used in a wide range of commercially available products including sun screens, cosmetics, shoe polish, crayons and even tennis racquets.
The federal government says it has been assessing therapeutic products containing nanotechnology components for many years.
"Fumed silicon dioxide nanoparticle aggregates for example, have been use in food, cosmetics and pharmaceuticals for about half a century and carbon black nanoparticles have been used in rubber products for more than a century," a health department spokesperson says.
Sunblock creams using zinc oxide and titanium dioxide nanoparticles are also being manufactured in Australia.
But Dr Paul Wright, associate professor in immunotoxicology at RMIT University and director of the research network Nanosafe Australia, says rapid recent developments highlight the need for caution.
He says engineered nanoparticles have unique and properties compared to the sort of particles BéruBé has been looking at.
"These are derivitised, these are functionalised nanoparticles, they can have totally unknown effects on the biological system," he says.
Dr Sam Bruschi is a consultant in medicinal chemistry, who recently finished a review of nanotech safety issues for the Office of the Australian Safety and Compensation Council.
He says the little that we do know about the health impact of nanotechnology has raised some red flags.
He says animal studies have found pre-cancerous lesions like fibrosis and granulomas in mice that have had carbon nanotubes aspirated into their lungs.
Tumours associated with titanium nanoparticles, which are used in sunscreen, have been found in research animals, he says. And in the lab, "quantum dots kill cells quite happily".
"There are some smoking guns out there and all we have to do is find the bullets," he says.
Because of their size, nanoparticles can evade the body's normal respiratory and immune defences and once inhaled or absorbed through the skin, potentially finding their way into the nervous and circulatory systems and becoming deposited in organs including the brain.
Much of the concern has also focused on carbon nanotubes, because of fears they are the right size and shape to act like deadly asbestos fibres.
BéruBé says until we have microscopes powerful to actually track where nanoparticles are going in the environment and in our bodies, and what they actually do there, the jury must remain out about any pending health catastrophe.
"We don't have the technology there to see exactly what these particles are doing, so we can't tell you exactly what the health impacts will be," she says.
"Unregulated use [of nanoparticles] could open society up to the asbestos of the 20th century.
"But we've been living with [combustion-derived nanoparticles since caveman times and we've learned to adapt to it."
This story was first posted on 1st December 2006.