Are cars nanotube factories on wheels?
Cars appear to produce carbon nanotubes, and some of the evidence has been found in human lungs. Researchers have detected the presence of carbon nanotubes in cells extracted from the airways of children. Similar nanotubes were also found in the exhaust of cars. Given that nanotubes were present in all of the patients, population exposure to nanotubes may be widespread, but exposure was not quantified in the course of the study.
Rice University scientists working with colleagues in France have detected the presence of man-made carbon nanotubes in cells extracted from the airways of Parisian children under routine treatment for asthma. Further investigation found similar nanotubes in samples from the exhaust pipes of Paris vehicles and in dust gathered from various places around the city. The analyzed particulate matter found in the alveolar macrophage cells (also known as dust cells) help to stop foreign materials like particles and bacteria from entering the lungs. The cells were taken from asthma patients aged 2 to 17 who underwent routine bronchoscopies as part of their treatment. Therefore, the researchers conclude that carbon nanotubes are likely to be found in everybody.
Fullerene molecules are commonly produced by volcanoes, forest fires and other combustion of carbon materials. Only a little catalysis is needed to make carbon nanotubes instead of fullerenes. A car’s catalytic converter, which turns toxic carbon monoxide into safer emissions, bears a similarity to the Rice-invented high-pressure carbon monoxide process to make carbon nanotubes.
Certain carbon nanotube fibers may act like asbestos, a proven carcinogen. Long carbon nanotubes and large aggregates of short ones can induce a granulomatous (inflammation) reaction. The concentrations of nanotubes are low in these samples that it might be hard to believe they would cause asthma. Nonetheless, carbon nanotubes were the major component of the carbonaceous pollution found in the samples.
Source: Rice University News & Media (press release)
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