Can Asbestos Help Us Understand Nanotoxicity?

Roland Piquepaille writes "Occupational Hazards is running an interesting article about how using our knowledge of asbestos could help us to assess the risks from nanoparticles, or their 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. 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."

Comments

Asbestos?

[geomon]

I'm not sure if asbestos is an appropriate analog for nano-based respiratory hazards. When Dr. Irving J. Seilkoff published his report on the link between asbestos and respiratory ailments, there was already an abundant record of impairment in the form of asbestosis. Asbestosis is a scarring and sedimentation of the lung due to particulate inhalation. It is in a general family of respiratory ailments known as pneumoconiosis. That group includes silicosis (affects quarry workers) and black lung (coal miners). The link that Seilkoff is credited with is the connection of asbestos to lung cancer, which is has only one known asbestiform species in direct connection: crocidolite. This blue amphibole was used in ship construction and in homes in and around Australia (sorry mates!). This asbestiform mineral has been directly connected to one of the most virulent forms of lung cancer, mesothelioma. This cancer of the plural lining is fatal within months of diagnosis.

Connections between other asbestiform minerals and cancer is more complex. Tremolite and serpentenite have also been linked to lung cancer, but the connection is much more tenuous. Another factor that would complicate the study of asbestos as an analog is the size: an asbestos fiber is counted for toxicological purposes only when it fits a 5:1 aspect ratio and is >5 micron in length. That is the geometry that is most likely to fit into the alveoli. This deep penetration of asbestos into the tissues of the lung is presumed to be the mechanism that leads to cancer. Plaques form around the embedded spines of asbestos as microphages attack and envelope the fibers. This process leads to a general lessening of the effective surface area for gas transfer leading to shortness of breath. The mechanics leading to cancer, however, are dubious and have plagued researchers for more than two decades.

I can't see how the study of asbestos can illuminate any area of occupational health. I can, however, see how injury claims attorneys would use the experience of asbestos litigation in any future attack on the nano-industry.

We know how to make non-toxic buckyballs

[vik]

That study is somewhat old hat. Have a look here and you'll see that the mechanism is now understood.

In short, you can make toxic, or non-toxic buckyballs. The more bits you dangle on the outside of the buckyballs, the less toxic they become. Nanomachine designers will be aware of this and act accordingly.

Vik :v)