Carbon nanotubes
© Fathi Moussa/Paris-Saclay University
Carbon nanotubes (the long rods) and nanoparticles (the black clumps) appear in vehicle exhaust taken from the tailpipes of cars in Paris.
Some potentially disturbing news out of France this week: Researchers studying the lungs of young Parisian asthma patients have found evidence that man-made carbon nanotubes are becoming a common air pollutant.

Carbon nanotubes are deliberately manufactured in several industries — their unique physical properties make them useful in electronics and nanotechnology, especially. But they can also be created accidentally, as a byproduct of catalytic converters in automobile engines.

The study — conducted by researchers in Paris and at Rice University in Houston — found that carbon nanotubes from the asthma patients' lungs are similar to nanotube samples taken from the exhaust pipes of Paris vehicles.

It's apparently not just a local problem, either: The samples are also similar to nanotubes found in Houston, in spider webs in India and even in polar ice cores.

No direct linkage is suggested between the nanotubes and asthma, but previous studies have questioned whether carbon nanotubes might act like asbestos, a known carcinogen.

"The concentrations of nanotubes are so low in these samples that it's hard to believe they would cause asthma, but you never know," says chemist Lon Wilson in press materials provided by Rice University. "What surprised me the most was that carbon nanotubes were the major component of the carbonaceous pollution we found in the samples."

The lung cells were taken from 69 randomly selected asthma patients in Paris between the ages of 2 and 17, and detected by high-resolution electron microscopy equipment. The nanotubes so small — from 10 to 60 nanometers in diameter — that traditional optical microscopes would not have been able to spot them.

Because nanotubes were found in all of the samples, the study led the researchers to conclude that carbon nanotubes are likely to be found in everybody.

Wilson says the carbon nanotubes samples were detected in heavy concentrations in the car tailpipes, but were also found in random swabs of dust in and around the city.

"It's kind of ironic. In our laboratory, working with carbon nanotubes, we wear facemasks to prevent exactly what we're seeing in these samples, yet everyone walking around out there in the world probably has at least a small concentration of carbon nanotubes in their lungs," he said.

The study was published this week in the journal EbioMedicine.

Source: Phys Org