Researchers studying a patient with a rare lung disease called hard-metal pneumoconiosis say the disease was probably caused by vaping.
The condition creates an unusual and distinctive pattern of damage to the lungs that results in breathing difficulties. It is typically diagnosed in people who work with "hard metals", such as cobalt or tungsten, in jobs like tool sharpening, diamond polishing or making dental prosthetics.
The researchers say the case history, published in the European Respiratory Journal , is the first known case where the disease has been linked to vaping.
In an editorial in the same edition of the journal, the European Respiratory Society explain why they do not recommend e-cigarettes as an aid to quitting smoking .
The case history was reported by Kirk Jones MD, Clinical Professor of Pathology, and Rupal Shah MD, Assistant Professor of Medicine in the Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, both from the University of California, San Francisco, USA, and their colleagues.
Professor Jones said: "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. When we diagnose it, we are looking for occupational exposure to metal dust or vapour, usually cobalt, as a cause.
"This patient did not have any known exposure to hard metal, so we identified the use of an e-cigarette as a possible cause."
Hard-metal pneumoconiosis causes damaged lung cells to engulf other cells and form 'giant' cells that can be seen clearly under a microscope. It can result in permanent scarring in patients' lungs with symptoms such as breathing difficulties and chronic coughing. This scarring cannot be cured, although some patients may have mild improvement if the exposure to hard-metal dust stops and they are treated with steroids.
When researchers tested the patient's e-cigarette, a personal vaping device used with cannabis, they found cobalt in the vapour it released, as well as other toxic metals - nickel, aluminium, manganese, lead and chromium.
Previous research has also found these metals in vapour from other e-cigarettes and researchers say they believe the metals are coming from the heating coils found in vaping devices, rather than from any particular type of re-fill.
Dr Shah said: "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.
"We think that only a rare subset of people exposed to cobalt will have this reaction, but the problem is that the inflammation caused by hard metal would not be apparent to people using e-cigarettes until the scarring has become irreversible, as it did with this patient."
Professor Jones added: "People who vape are often looking for a safer alternative to smoking. But 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.
"We believe it is likely not just that this will happen again, but that it has happened already but not been recognised. One of our major reasons for publishing this case history is to inform our colleagues about the possible risks involved with vaping."
The European Respiratory Society's editorial on smoking cessation highlights some of the issues of using e-cigarettes as an alternative to smoking and concludes that: "The tobacco harm reduction strategy is based on well-meaning but incorrect or undocumented claims or assumptions."
Editorial co-author Jørgen Vestbo, Professor of Respiratory Medicine at the University of Manchester, UK, said: "Research on e-cigarettes is still less developed than it is for smoking. However, there are a number of new studies showing that vaping affects the lungs and, in addition, we are now beginning to see patients diagnosed with acute vaping-related lung disease.
"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."
European Respiratory Journal