Last updated January 31, 2018 at 4:58 pm
New research published in the journal Cell Press has suggested that carbon nanotubes may have the same cancer-causing effect as asbestos.
Carbon nanotubes are one of the great advances in modern materials and manufacturing. The nano-sized tubes are incredibly strong, small and lightweight, which has seen them used in a range of products including aircraft, bicycles and computer motherboards.
But the study, which was carried out in mice, found that long and thin nanotubes induced the formation of mesothelioma in around 10-25% of the animals.
Mesothelioma is a malignant and deadly lung cancer discovered to have been caused by exposure to asbestos dust, which are actually extremely fine fibres. After inhalation these fibres become embedded in lung tissue and destroy cells by a process called necrosis. This results in inflammation in the surrounding area, leading to cancer development. A similar process was thought to be involved with the carbon-induced cancers.
The investigators placed long carbon nanotubes in the pleura – the area around the lungs where mesothelioma develops in humans. They then were able to track the changes to the pleura throughout disease development, monitor the onset and stages of inflammation, and the changes in genes that are the gatekeepers of cancer development. The mesothelioma that formed as a result of the long carbon nanotubes mice was similar to tumour samples from human patients.
The research has also revealed new information about the formation of mesothelioma itself. As mesothelioma is often diagnosed when it’s quite advanced, not much is known about the early mechanisms by which it forms. It was found that the long-term inflammation caused by the nanotubes resulted in the silencing of genes known to be affected in mesothelioma, drawing a direct link between the inflammation and some of the genetic effects seen in the human tumours. It is also hoped the findings around the early stages of mesothelioma could help find biomarkers for early detection, or targets for therapies.
While this isn’t the first time a link between carbon nanotubes and mesothelioma has been found, it is the first long-term study to show the effect. “Unlike previously reported short-term studies, this is the first time the effects of long and thin carbon nanotubes, leading to mesothelioma, have been monitored in mice over many months,” said senior author Marion MacFarlane from the Medical Research Council Toxicology Unit in England.
However, researchers not involved with the study have cautioned that the finding is not something for most people to worry about.
The mesothelioma-causing effect of nanotubes was only found with long nanotubes. Shorter tubes or tangles didn’t cause cancer formation as the body was able to remove them before they caused damage.
The likelihood of long carbon nanotubes becoming airborne and breathable is also extremely low. According to Professor Ivan Kempson from the University of South Australia, “these materials are typically embedded within other materials such as resins within products. There is very little chance of the nanotubes… becoming isolated from the product and able to be inhaled by an individual.”
The research also injected the carbon nanotubes directly into the pleura of the mice, so it is not definitively known whether inhaled airborne nanotubes would even reach the pleura.
Instead, the greatest risk exists for people involved in making carbon nanotubes, who are most likely to encounter “free” nanotubes. “The greatest risk occurs for workers involved in the manufacture and handling of these materials,” said Kempson. “This research provides important awareness for guidance on creating safe workplaces.”
Carbon nanotube structure image courtesy of AJC1 on Flickr