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Honolulu, HI, United States, 2006/07/25 - A new toxicological study of carbon nanotubes (CNTs) doped with nitrogen found clear differences in the toxicological aspects and biocompatibility compared to multiwalled or singlewalled CNTs..
Scientists and toxicologists have not reached any consensus yet on the level of toxicity of CNTs although there are indications that under certain circumstances they might be hazardous. However, if CNTs are to be used in novel products, then they are likely to get in contact with the human body through the skin and access the inner organs through the respiratory and digestive tracts. During manufacture, carbon nanotubes may enter the respiratory airways of the workers, and accumulate in the lungs. If nanotubes are used as fillers in food packaging products, then they could reach the stomach and intestines of the consumers. If cosmetics and bio-filters are developed using nanotubes, then they will certainly get in contact with human skin.
This is the reason why a number of researchers have taken up toxicological studies of CNTs. One of them is Professor Mauricio Terrones from the Advanced Materials Department at IPICyT in Mexico. He explained his recent study's findings to Nanowerk:
"In general we found that nanotubes (pure carbon multiwalled and N-doped multiwalled) are not harmful if they are ingested or inhaled by mice. However when the CNTs are introduced intratracheally into the mice, our N-doped nanotubes are far more tolerated and did not cause the death of any mouse. Even extremely high concentrations of N-doped nanotubes administrated directly into the mice’s trachea only induced granulomatous inflammatory responses. In contrast, pure multiwalled CNTs caused the death of the mice when treated intratracheally at high doses."
Read the full story on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk LLC.