A Californian woman who had been vaping cannabis oil has been diagnosed with a rare type of lung scarring that is usually only seen in industrial metalworkers.
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The case, recently reported in the European Respiratory Journal, has prompted more warnings about the dangers of vaping, particularly vaping liquids that contain THC (tetrahydrocannabinol).
The 49-year-old woman was diagnosed with a condition called hard-metal pneumoconiosis, despite having no known history of exposure to hard metals such as cobalt or tungsten.
Hard-metal pneumoconiosis causes a distinctive pattern of lung tissue scarring, and this is the first case study to suggest that that the condition can be caused by vaping.
This patient did not have any known exposure to hard metal, so we identified the use of an e-cigarette as a possible cause."
Study author Kirk Jones, Clinical Professor of Pathology, University of California, San Francisco
Toxic metals were found in the vapor released from the e-cig
When Jones and colleagues tested the e-cigarette, which was used with cannabis oil, they found cobalt and other toxic metals in the vapor is released. The researchers concluded that the metals were released from the heating coils inside the device. The other metals identified were nickel, aluminum, lead, magnesium, and chromium.
Jones says: "Hard-metal pneumoconiosis is diagnosed by looking at a sample of patient's lung tissue under the microscope. It has a distinctive and unusual appearance that is not observed in other diseases."
He says that when diagnosing it, he usually looks for occupational exposure to metal dust or vapor, usually cobalt, as a cause.
Co-author Rupal Shah says exposure to cobalt dust is extremely rare outside of a few specific industries: "This is the first known case of a metal-induced toxicity in the lung that has followed from vaping and it has resulted in long-term, probably permanent, scarring of the patient's lungs."
Shah adds that the team thinks that only a rare set of people exposed to cobalt will have this reaction. However, the inflammation caused by exposure to hard metals would not become apparent to e-cigarette users until the scarring has become irreversible, as it has done with this patient, he explains.
Another reason to avoid vaping cannabis oil
Medical director at the British Lung Foundation, Nick Hopkinson, warns that this latest case linked to vaping cannabis oil was another reason to avoid it: "The higher temperature involved in vaping cannabis oil compared to normal products may increase the risk that metal from the heating element is inhaled."
He recommends that people in the UK who vape only use products regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). He also advises that while vaping is much safer than traditional smoking, people who vape should try to quit that too, although not at the expense of going back to smoking.
Other scientists agree that, while cannabis oils should be avoided, vaping is still a better alternative to smoking cigarettes.
Professor John Britton, director of the UK Centre for Tobacco & Alcohol Studies, says: "There is nothing in this new paper that should change advice to smokers. If you smoke, switch. If you don't smoke, don't vape. And just as you wouldn't buy unlicensed alcoholic drinks, don't vape cannabis or other bootleg products."
European Respiratory Society says it cannot back vaping
The publication of the case study comes just as the European Respiratory Society stated that it cannot back vaping as a safe aid to quitting smoking and that there is no evidence that alternative nicotine products are safe.
In an editorial, the society's Tobacco Control Committee stated that current health policies are based on well-meaning but incorrect or undocumented claims or assumptions: "Evidence on the safety and the effectiveness of alternative nicotine delivery products as a smoking cessation tool is still lacking, while use of nicotine-containing products is spreading to non-smokers, which is most alarming."
E-cigarettes are harmful, they cause nicotine addiction and can never substitute for evidence-based smoking cessation tools. The medical profession, as well as the public, should be concerned about a new wave of lung diseases caused by a product which is heavily promoted by the tobacco industry."
Jorgen Vestbo, Professor of Respiratory Medicine, University of Manchester
Professor Jones also warns that vaping might not be as safe as people think it is: "As lung physicians, it is our job to be concerned about the substances that are inhaled into the lung, particularly those substances that can bypass our usual defence mechanisms such as these ultra-fine mists."
"One of our major reasons for publishing this case history is to inform our colleagues about the possible risks involved with vaping," he concludes.