Carbon nanotubes, described as “the wonder material of the 21st century” are found in a wide range of products. However, a recent publication in the journal Nature Nanotechnology suggests that certain forms of carbon nanotubes, if inhaled in large quantities, could be as much of a health hazard as asbestos.
Asbestos fibres have been shown to induce lesions within the lining of the lungs which eventually become mesothelioma, a lethal form of cancer. Specifically, the long, thin fibers of asbestos enter the lungs and penetrate deep within the tissue lining. This characteristic pattern makes it impossible for the body’s immune system to naturally clear the airway of this obstruction. Though the production and usage of asbestos has been severely reduced over the last 25 years, during the 1940s and 50s it was linked to one of the worst and most costly occupational health disasters in American history. Unlike asbestos, the potential hazards of carbon nanotubes are not fully understood.
A team of researchers, led by Professor Kenneth Donaldson of the University of Edinburgh, investigated whether certain lengths of carbon nanotubes could provoke a pathological response known to be a sign of mesothelioma. Four groups of mice were used for the study. Each group was injected in the abdomen with a different substance, either short nanotubes, long nanotubes, asbestos or small carbon clumps. Of the four divisions, the researchers found that only the long carbon nanotube and asbestos treatments induced lesions.
Professor Shana O. Kelley, who holds an appointment from the Faculty of Medicine, Biochemistry and Faculty of Pharmacy at the University of Toronto, currently employs nanotechnology as part of her research and was not involved in the study. Dr. Kelley points to the fact that since this study injected “relatively large quantities of carbon nanotubes—this scenario bears little resemblance to any kind of environmental exposure that the average person could experience, it’s not reasonable to extrapolate the findings of this study to predict that carbon nanotubes currently pose any type of public health risk.” In particular, Dr. Kelley explains that “the comparison to asbestos, which is an inhalation hazard at much lower levels, is somewhat questionable. For example, most of the nanoscale biomedical sensors that are being developed [which use] carbon nanotubes as a platform will not be affected. [Alternatively], large-scale industrial applications may need to be pursued with adequate protection for workers handling the materials.”
Structurally, carbon nanotubes are atom-thick sheets of graphite formed into concentric cylinders. They can be found in lengths ranging from a few nanometers to upwards of one hundred thousand nanometers. However, their most miraculous characteristic is a dainty structure that allows them to be as light as a feather, while maintaining strength comparable to steel.
In recent years, a substantial amount of research has been aimed at developing carbon nanotubes for use in new drugs, disease identification models, and advanced electronics. Currently, nanotubes can be found in such commonplace items as tennis racquets and baseball bats. Yet since their discovery, scientists have feared that the small needle-shaped nanotubes might cause diseases similar to those brought about by asbestos fibers.
Given these current findings, this study may act as a wake-up call for the ways in which large-scale production and handling of these materials have been undertaken. In terms of the research community, Dr. Kelley says that there is a hope that granting agencies as a whole “will continue to devote much of their research funding [towards] new applications of nanotechnology, while still supporting studies that evaluate the safety of new materials.”
