Can asbestos help us understand nanotoxicity?
Today, it's unknown if nanomaterials under development are dangerous to human beings or to our environment. Some people think that nanoparticles can move to our lungs or our brains, presenting a significant threat to our health. Other scientists think there is no danger because we have been exposed to nanoparticles for thousands of years, such as ashes from volcanic eruptions. So it's interesting to read in Occupational Hazards that using our knowledge of asbestos could help us to assess the risks from nanoparticles, or their nanotoxicity. For example, nanotubes which are now used for many industrial developments, have similar shapes as fibers like asbestos, being long and extremely thin. And like nanomaterials today, asbestos was considered as harmless when humans were exposed to it. While the comparison has some merit, more research needs to be done before drawing any conclusion.
The subject of nanotoxicity was discussed during the second international symposium on Nanotechnology and Occupational Health which was held in Minneapolis on October 3-6, 2005.
During this conference, Fionna Mowat, from Exponent, gave a presentation named "Nanotoxicity: What Can We Learn from Other Small Particles and Fibers?."
Here are some highlights, as reported by the Occupational Hazards article.
While Mowat's presentation, like many others at the symposium, raised more questions than answers, she concluded that current knowledge of materials such as asbestos, welding fumes and ultrafine particulate matter may be useful in the assessment of the toxicity of nanomaterials.
Drawing a possible parallel to asbestos, Mowat noted that asbestos once was considered a "miracle mineral" before it was discovered to be a human health risk at certain doses.
"Materials like asbestos show us we really need to use caution when developing novel materials and [we need to] use the information we have to develop a health risk assessment paradigm," Mowat said.
From what Mowat said, it's hard to conclude if nanomaterials are as dangerous as is asbestos, which continues to kill thousands of people every year.
But it's interesting to note that the smallest nanostructures might potentially be less dangerous to humans than larger ones.
Current research on asbestos also suggests that assumptions about the health hazards of nanoparticles based on their size may be a bit counterintuitive. Such research indicates "that it is actually the longer fibers that cause harm, as the smaller fibers are easily cleared or dealt with by the body," according to Mowat.
Mowat mentioned in her presentation that asbestos research may be "particularly relevant" to nanotubes. Nanotubes are extended tubes of rolled graphite sheets -- favored for their strength, flexibility and conductivity -- which typically are a few nanometers in diameter and several micrometers to centimeters long.
Even if the article offers an intriguing perspective on how to assess the potential risks of nanomaterials, it is in fact just giving a new path for future research to scientists. The nanotoxicity discipline is so new that information about it is still scarce. But here are two links on Wikipedia and at the Institute of Science in Society in London, U.K.
And as far as I know, nobody can conclude today that products developed using nanotechnology are dangerous to our health or not. But feel welcome to tell me what you think.
Sources: Josh Cable, Occupational Hazards, October 18, 2005; and various web sites
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