The air our children breathe seems to be full of carbon nanotubes that damage lung function; this has just been revealed by a medical study published in the journal Ebiomedicine. The problem is made all the more delicate by the fact that it is very difficult to pinpoint the source.
Ahe fine particles in our polluted cities are known to cause the premature death of 42,000 people a year in France. But these tiny components have never really been characterized... By studying the contents of the lungs of some sixty asthmatic children, scientists have been able to identify the presence of carbon nanotubes, which seems to be the main material of carbon pollution found in the pulmonary alveoli. The online medical journal Ebiomedicine has just published thehe results of the study in an article entitled "Anthropogenic carbon nanotubes found in the respiratory tracts of Parisian children".
The work was carried out by the team of Prof. Fathi Moussa (specialist in analytical chemistry) of the University of Paris-Saclay, in collaboration with Lon J. Wilson of Rice University based in Houston, USA. The chemists studied the airway fluid of 69 asthmatic children, including their macrophages, which trap and remove foreign particles. They found the systematic presence of carbon nanotubes. "These nanostructures are similar to those found in dust and vehicle exhaust collected in Paris, as well as those previously observed in ambient air in the United States in spider webs in India, and in ice cores, underline the authors. These results strongly suggest that humans today are routinely exposed to carbon nanotubes from anthropogenic sources.
Proven lung toxicity
The aggregates of nanotubes found in cells range in size from 10 to 60 nanometers in diameter and up to several hundred nanometers in length. They are too small to be detected by light microscopy. Scientists have used high-resolution electron microscopy, X-ray spectroscopy, Raman spectroscopy and near-infrared fluorescence microscopy to identify nanotubes in cells and environmental samples.
The news is worrisome: if nanotubes are ubiquitous, toxicologists may be concerned. Numerous studies have shown that nanotubes, by accumulating as biopersistent fibres, can cause inflammation and oxidative stress, precursors to cancer. (1). In addition, they are capable of transporting other pollutants very well.
Already in 2003, at the first EuroNanoForum 2003 in Trieste, Vicki Colvin, Director of the Centre for Biological and Environmental Studies of Nanotechnology (CBEN) at Rice University, spoke about the "asbestos-like" effects of carbon nanotubes and their oxidizing properties. "Early risk assessment is the only way to protect the industry, she had pointed out. Media amplification of health problems must be avoided."(2).
Where do these pollutants come from?
The American chemist Lon J. Wilson wonders about the origin of these nanotubes. He wonders whether the catalytic systems in vehicles are not of real nanotube factoriesby converting carbon monoxide into nanotubes.
Unless industrial sources are involved. Indeed, nanotubes are used today in multiple applications for their exceptional optical, electrical and thermal properties as well as their resistance and lightness. They are therefore found in engine parts, bicycle frames, mobile phone components, plastic parts for electrostatic painting, fuel tanks, high-capacity battery components, etc. "Do you want more and more electronics or smart textiles with heart rate sensors and nanotubes in them?" asks NewScientist magazine. The market for carbon nanotubes is currently in the order of 500 to 1,000 tons per year, with a leading manufacturer in Europe, the Belgian company Nanocyl. While Bayer has stopped its production of "baytubes", Arkema, which had developed a prototype at Lacq, produces most of its nanotubes in Asia, where the users and integrators are located.
(1) Outdoor air pollution and asthmaGuarnieri M, Balmes JR . Lancet, 3 May 2014
(2) Le Meilleur des nanomondes, Dorothée Benoit Browaeys, p23, Buchet-Chastel, 2009.