2005 December 04 Sunday
Support Builds For Nanomaterials Safety Regulations

Fear of nanomaterials toxicity is leading to greater regulatory agency interest.

Nanomaterials are already being integrated into a wide range of products, including sports equipment, computers, food wrappings, stain-resistant fabrics and an array of cosmetics and sunscreens -- a market expected to exceed $1 trillion a year within a decade. Preliminary studies suggest that most of these products do not pose significant risks in their bulk form or embedded in the kinds of products that so far use them.

But the same cannot be said of the particles themselves, which can pose health risks to workers where they are made and may cause health or environmental problems as discarded products break down in landfills.

Lab animal studies have already shown that some carbon nanospheres and nanotubes behave differently than conventional ultrafine particles, causing fatal inflammation in the lungs of rodents, organ damage in fish and death in ecologically important aquatic organisms and soil-dwelling bacteria.

I look at this intuitively: One of the reasons scientists make nanoscale particles is that the same materials behave differently if made using much smaller sizes. The small sizes powerfully change behavior. For example, carbon tubes make miniature springs that do not wear out and that might be useful in human joints to increase ability to absorb strong shocks. But with greater changes in behavior come greater risk of unexpected and undesired side effects. Well, this intuitive expectation is being borne out by recent experiments as the previous article reports.

Some recent work at Lawrence Berkeley National Laboratory found that both nanotubes and nano-onions (really, I am not making this up) cause changes in gene regulation and cell division.

The increasing use of nanotechnology in consumer products and medical applications underlies the importance of understanding its potential toxic effects to people and the environment. Although both fullerene and carbon nanotubes have been demonstrated to accumulate to cytotoxic levels within organs of various animal models and cell types and carbon nanomaterials have been exploited for cancer therapies, the molecular and cellular mechanisms for cytotoxicity of this class of nanomaterial are not yet fully apparent. To address this question, we have performed whole genome expression array analysis and high content image analysis based phenotypic measurements on human skin fibroblast cell populations exposed to multiwall carbon nano-onions (MWCNOs) and multiwall carbon nanotubes (MWCNTs). Here we demonstrate that exposing cells to MWCNOs and MWCNTs at cytotoxic doses induces cell cycle arrest and increases apoptosis/necrosis. Expression array analysis indicates that multiple cellular pathways are perturbed after exposure to these nanomaterials at these doses, with material-specific toxigenomic profiles observed.

You've no doubt heard about the health benefits of onions. Well, nano-onions are better for you than nanotubes.

Chen and colleagues found that exposure to the nanotubes and nano-onions activated genes involved in cellular transport, metabolism, cell-cycle regulation and stress response. Multi-walled carbon nanotubes induced genes related to a strong immune and inflammatory response, while the presence of nano-onions caused most changes in genes induced in response to external stimuli. The nanotubes appeared to be ten times more toxic than the nano-onions.

These sorts of effects are potentially useful in medical research. The power of nano-materials like any capability is a double-edged sword. The ability to effect changes in the environment is useful or harmful in different contexts. Nothing new about that idea. Just different kinds of materials creating the promise and the risk.

On the bright side, research on nanomaterials toxicity has turned up ways to reduce the toxicity.

Researchers from Rice University, US, have found that the toxicity of water-soluble carbon nanotubes to human skin cells decreased as the functionalization of the tubes increased. The results are similar to the team's findings for fullerene molecules last year, although the nanotubes were generally less toxic than the fullerenes.

I expect nanotechnology to bring orders of magnitude more benefits than costs - at least as long as we do not make nano-replicators.

By Randall Parker    2005 December 04 09:49 PM   Entry Permalink | Comments (8)
2003 January 21 Tuesday
Nanotech To Enable New Types Of WMD

Nanotechnology will make it possible to develop new kinds of weapons of mass destruction.

Nanotechnology has the potential to create entirely new weapons. Fourth-generation nuclear weapons are new types of nuclear explosives that would use inertial confinement fusion (ICF) facilities.

The defining technical characteristic of fourth-generation nuclear weapons is the triggering - by some advanced technology such as a superlaser - of a relatively small thermonuclear explosion in which a deuterium-tritium mixture is burnt in a device whose weight and size are not much larger than a few kilograms. Since the yield of these warheads could go from a fraction of a ton to many tens of tons of high-explosive equivalent, their delivery by precision-guided munitions or other means will dramatically increase the fire-power of those who possess them - without crossing the threshold of using kiloton-to-megaton nuclear weapons, and therefore without breaking the taboo against the first-use of WMD. Moreover, since these new weapons will use no (or very little) fissionable materials, they are expected to produce virtually no radioactive fallout.

The problem this poses is that as nanotech manufacturing equipment becomes available for purchase many more groups and countries will be able to make weapons that are currently beyond their technical ability to build. The ability to build nuclear weapons with little or no fissionable materials will remove another obstacle. Countries that are now struggling to buy and build uranium and plutonium enrichment facilities (e.g. Iraq, Iran, North Korea, and perhaps Libya) will suddenly find that the size of that problem will shrink by orders of magnitude.

The threats posed by the spread of WMD into the hands of more governments and to terrorist organizations will grow enormously as technology advances throughout the 21st century.

By Randall Parker    2003 January 21 08:55 AM   Entry Permalink | Comments (3)
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