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Nanoparticles Scrutinized for Health Effects

Windows cleaned by raindrops, white sofas immune to red wine spills, tiles protected from limescale buildup - new products created from minute substances called nanoparticles are making such domestic dreams come true.

Based on tiny particles 10,000 times thinner than a strand of hair, the products are some of the early widespread applications of nanotechnology, the science of manipulating atoms and molecules. Nanoparticles are showing up in everything from fabric coatings to socks to plush teddy bears.

In the best-case scenario, these nanoparticles are harmless and can help spare the environment from the overuse of polluting cleaning agents.

[Related story: It's difficult to spot retail nanotechnology]

But some scientists are concerned that these seemingly magical materials are hitting the market before their effects on human health and the environment have been sufficiently studied.

If a chemical substance has been commercialized before, on a larger than nano-scale, and is included in the Toxic Substances Control Act Chemical Substance Inventory, it is considered as "existing" by the U.S. Environmental Protection Agency - and the nano-scale version of the material requires no further testing.

Scientists such as Jennifer Sass of the Natural Resources Defense Council say they think that's a mistake, and that nanoparticles should be treated as new and different materials.

That's because the few scientific reports available suggest that nanoparticles can pose a threat to human health and to the environment. For example, fish swimming in water containing modest amounts of fullerenes, soccer-ball-shaped nanoparticles made out of 60 carbon atoms, showed a large increase in brain damage. These are the same types of fullerenes being used in various skin products.

Another study showed that rats exposed to manganese oxide nanoparticles accumulated them in the brain.

Warning on nanoparticles

Scientists also have shown that very small nanoparticles, called quantum dots, penetrate pigskin. Other studies suggest that from the skin, they can travel through the lymphatic duct system to lymph nodes and eventually end up in organs such as the liver, kidney and spleen.

And when inhaled, nanoparticles will go deeper into the lungs than larger particles and reach more sensitive parts. Because of that, scientists are particularly concerned about nanoparticles being used in spray products.

"We have research showing that as a material shrinks in size, it becomes more harmful to the lungs. Nanoparticles tend to be more inflammatory to the lung, and it seems as if the lung has to work harder to get rid of them," said Andrew Maynard, chief science adviser at the Project on Emerging Nanotechnologies in Washington. The project was established in 2005 by the Woodrow Wilson International Center for Scholars and the Pew Charitable Trusts to ensure that the potential benefits of nanotechnology are realized, at the same time possible risks are minimized.

Full Story: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/05/11/BU4P10BB88.DTL