Wednesday, September 23, 2009

Carbon Nanotubes: 21st Century Asbestos?

By Wade Rawlins

Tiny carbon nanotubes — lattices of carbon far smaller than the width of a human hair —possess extraordinary physical and chemical properties and may find many new uses from delivering medicine directly to tumors to miniaturizing electronics to building lighter weight space craft and bicycles.

While seeing their potential promise, scientists also have voiced concerns about the potential toxicity of carbon nanotubes because they share similiarities with asbestos fibers.

A recent article by French researchers in the journal Particle and Fibre Toxicology examines the question: Do asbestos and carbon nanotubes pose similar health risks?

Exposure to tiny asbestos fibers is closely linked to serious human respiratory diseases including lung cancer, mesothelioma, a cancer of the lining of the lungs and abdomen, and asbestosis, a scarring of the lungs that causes difficulty breathing.

Carbon nanotubes have fiber-like characteristics in their thin and elongated shape and ratio of width to height, scientists at the University of Paris write in the article. And they’re so small that humans may inhale them unknowingly just as people do airborne asbestos fibers, causing them to penetrate deep into the lungs and stay there.

In view of the carcinogenic properties of asbestos, and the widespread toll it has taken on human health and society, the researchers say it’s important to determine the safety of carbon nanotubes to protect ecological systems and human health.

They note that in several studies involving animals and cell cultures, carbon nanotubes have already triggered adverse effects similar to those observed with asbestos fibers. Two recent studies by Japanese researchers showed the occurrence of malignant mesotheliolma in mice and rats exposed to carbon nanotubes.

“These initial results underline the urgent need for information to further our knowledge about carbon nanotubes,” the French scientists say.

They say that while carbon nanotubes are valuable industrial products with multiple applications, the legitimate concerns about their potential adverse effects need to be addressed. “Based on the available data in the literature …, it appears that carbon nanotubes may elicit responses similar to those caused by asbestos fibers,” they conclude.

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