Biopsies showed numerous giant multinucleated cells in the alveolar spaces
A regular vaper of cannabis has been diagnosed with a lung disease usually seen only in workers exposed to dust from hard metals such as cobalt or tungsten.
A case study by pathologists from the University of California San Francisco, published in the latest European Respiratory Journal, found giant cell interstitial pneumonia, AKA hard metal pneumoconiosis or cobalt lung, in a 49-year-old, otherwise healthy, woman. She had no other exposures to inhaled metals except for her cannabis vaping device, which she had been using for six months.
Presenting with shortness of breath on exertion, dry cough and wheezing, she had lung crackles, severely reduced diffusion capacity and moderately severe restriction.
Biopsies showed numerous giant multinucleated cells in the alveolar spaces, leading to the diagnosis of giant cell interstitial pneumonia – a finding highly specific to cobalt inhalation, the authors write.
Her vaping fluid was analysed and found to contain cobalt, as well as nickel, aluminium, manganese, lead and chromium, but not tungsten.
Analysis of her lung tissue did not reveal any cobalt, but the writers say this could be because cobalt is highly soluble in bodily fluids and rapidly excreted, and/or because the particles might be smaller than they could detect with FESEM-EDX (field emission scanning electron microscopy and energy dispersive X-ray spectroscopy).
Previous studies have found heavy metals in aerosolised vaping liquids, with one finding higher concentrations of nickel in e-cigarettes than in regular cigarettes.
The authors of the case study note that higher temperatures are required to aerosolise THC than nicotine, and previous studies have associated higher voltages with increased toxic emissions.
“Our results suggest that regulation of the material composition of the reservoir and heating coil in the vaporisation device should be sought to avoid toxic exposure when the device is being used as intended to vaporise cannabis oil,” they write. “The public health implications of this are substantial given the increasing trend towards legalisation of cannabis for recreational and medical purposes.”
E-cigarettes and vaping continue to make headlines in the mainstream media and in journals, with the US epidemic of EVALI (e-cigarette/vaping-associated lung injury) having reached almost 2300 cases and claimed almost 50 lives, according to the CDC.
Last month, in the first finding of its kind, the CDC said bronchoalveolar lavage samples from 29 patients had found vitamin E acetate in every sample. This is an oily substance used as a thickening agent in vaping products containing THC. Inhaling lipids can cause lipoid pneumonia, which is sometimes fatal.
But not all EVALI cases resemble lipoid pneumonia; Mayo Clinic pathologists in October described findings more consistent with chemical pneumonitis from inhaled toxins.
In an editorial in the December American Journal of Respiratory and Critical Care Medicine, John R. Balmes, professor of environmental health sciences at UC Berkeley, calls EVALI “a public health disaster” that could have been prevented by more pro-active and robust regulation.
In addition to lipoid pneumonia and pneumonitis, he notes that fluid excipients propylene glycol and glycerine have been shown to induce airway remodelling; that nicotine vapour can induce macrophage activation; and that byproducts from flavouring additives can injure the airway epithelium.
“It is really no surprise to anyone with a background in inhalational toxicology that when chemically complex extracts are heated to the point of aerosolisation and vaporisation, toxic agents will be generated,” Professor Balmes writes.
“The FDA was made aware of the potential harm of inhaling vapours of nicotine-containing aerosols but allowed tobacco company-funded companies like JUUL to market flavoured e-cigarette pods, which has led to the nicotine addiction of thousands of children.”
EVALI seems entirely confined to the US, which is awash with unregulated products and advertising is largely unfettered. The US also has strikingly higher rates of vaping among youth than the UK, where regulation is much tighter.
In a commentary in the latest International Journal of Public Health, Dr Wasim Maziak, professor of epidemiology at Robert Stempel College of Public Health and Social Work at Florida International University, says the rise of e-cigarettes represents the rehabilitation of the tobacco industry with the support of its erstwhile foes.
“[It] is not those who caution about e-cigarettes that need to be persuaded about tobacco harm reduction and nicotine, but the e-cigarettes industry, which while enjoying the free promotion of their products by members of the tobacco-control community, does not abide by any harm-reduction principle,” he writes.
Large reinsurers, nearly all of which already treat vapers the same as smokers, are renewing their warnings to life insurers, Reuters reported, urging them to exercise particular caution with young vapers and check whether they are using THC products.
European Respiratory Journal; 5 December, 2019
