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Dr Des Corrigan  writes on the current controversy in e-cigarettes and breaks down some of the terminology in ‘cannavaping’ 

Controversy has surrounded e-cigarettes since they were first appeared in 2006. Are they a valuable aid for those trying to quit smoking, or are they just another way of hooking young people on nicotine? These are just two of the questions this new technology has posed. Some believe they should be regulated as medical devices by the HPRA, while others favour the present unregulated free-for-all, on commercial grounds. 

The range of products is bewildering, as is the terminology used. A variety of names exist, including ‘e-cigarettes’, ‘e-cigs’, ‘mods’, ‘vape pens’, ‘vapes’, and even ‘electronic nicotine delivery systems’. Some look like cigarettes, cigars and pipes, while others resemble pens and USB sticks with refillable cartridges or pods. The latter are the dominant  product in the States, accounting for 70 per cent of sales. They work by using a battery-powered metal resistance coil to heat nicotine, flavourings, propylene glycol and vegetable glycerine in liquid form to produce an aerosol that users inhale into their lungs. That aerosol can contain (apart from the nicotine) volatile carbonyls, furans and reactive oxygen species, carcinogens, heavy metals (nickel, tin and lead), as well as ultra-fine particulate matter. A key flavouring is diacetyl, the inhalation of which is known to cause a form of bronchiolitis called ‘popcorn worker’s lung’. Since plant tissue is not being burned, as in a cigarette, many of the harmful pyrolysis products from either tobacco leaf or cannabis herb will not be produced. Therefore, a case can be made that e-cigarettes may be less harmful to the lung than conventional cigarettes and certainly Public Health England is of that view.

However, proponents of these devices may lose sight of the fact that nicotine is still a highly-addictive compound that can be embryotoxic, may harm adolescent brain development and is a recognised poison. Two RCTs found that nicotine-containing e-cigarettes can help smokers quit over the long term when compared to placebo non-nicotine-containing devices. It is vital, however, that those quitting use e-cigarettes alone and that they do not fall into the trap of becoming ‘dual users’, ie, smoking regular cigarettes and also using e-cigarettes. In the US, electronic cigarettes are most commonly used by high-school students, raising concerns about the impact on their developing brains and the risk of their becoming addicted to nicotine. The high level of vaping by young people has reversed progress in the decline in tobacco use by that age cohort. 

The controversy over these devices has intensified in recent months because of the emergence of what is now called EVALI in the US. The acronym stands for E Vaping Associated Lung Injury. At the time of writing, the Centres for Disease Control and Prevention (CDC) has reported 2,290 cases of ‘vape lung injury’, including 47 deaths. Cases have been reported from 49 states (Alaska is the exception) and involve mostly young white males, all with a history of vaping. Out of 867 patients for whom data is available, 86 per cent reported use of THC, 64 per cent nicotine, 52 per cent both THC and nicotine, 34 per cent only THC, and 11 per cent only nicotine. The THC-containing products were obtained particularly from street sources, friends, family members or illicit dealers. When samples were available for testing by the FDA, most were positive for THC but until recently, no one compound or ingredient had emerged as the cause of the injury to the lungs. Bronchoscopy samples from 29 patients were examined and vitamin E acetate identified in all samples. This is used in some THC-containing products to thicken the oil. Obviously, vitamin E acetate does not cause respiratory problems if taken orally or applied topically, but it is known that if it is inhaled, it may affect the lungs. Frantic efforts are underway to establish the exact cause of ‘vape lung’ and there has been a huge drop in sales and calls by politicians and health professionals, including the American Medical Association for bans on the advertising and sale of e-cigarettes. Not surprisingly, these calls have been matched by industry lobbying to prevent any attempt to curtail their profiteering.

 Much of the THC consumed in what is called ‘cannavaping’ is in the form of oily solutions in refillable cartridges, although some was used by ‘dabbing’ or ‘dripping’ of a THC-rich cannabis concentrate directly onto the heated coil of the e-cigarette. ‘Dabbing’ is a relatively new method of drug use that emerged from the development of ‘concentrates’ by the now-legal cannabis industry. These concentrates were originally supposed to be used to manufacture ‘edibles’ — cannabis products for medicinal use designed to be eaten as confectionery or drunk in beverages (beers or soft drinks) by those wishing to avoid smoking the drug. Some concentrates are made using dry processing methods, such as dry ice. 

Water-based methods provide what is known as ‘bubble hash’. Although organic solvents such as ethanol or acetone can be used, most commercial and indeed amateur concentrates are processed using a liquid gas, such as pressurised butane. Some pharmaceutical-grade extracts use supercritical fluid extraction technology with liquid carbon dioxide because no solvent resides remain after it evaporates off.

 Butane is particularly popular, giving rise to what is termed BHO (butane hash oil). Evaporation of the gas leaves a brown or yellowy-white solid with a low melting point. In slang terms, this is called ‘ear wax’, ‘crumble’, ‘honeycomb’, ‘shatter’ or ‘budder’, depending on its consistency and physical appearance. Such concentrates can have a THC content ranging from 69-to-95 per cent, depending on the potency of the starting cannabis plant material. Samples of BHO tested in the UK in 2016 gave THC contents ranging from 73-to-83 per cent with less than 1 per cent of CBD. To put that into context, herbal cannabis from the 1960s through to the late 1990s had between 1-and-3 per cent THC and hash had between 3 and 10 per cent.

Until the emergence of ‘cannavaping’, dabbing involved the application of a small amount of concentrate (a ‘dab’) to a nail made of titanium, which was then flash-vapourised with a butane flame, such as the popular crème brûlée torch. The vapour was then inhaled in a single puff through a water pipe. More THC is absorbed by ‘dabbing’ than by smoking marijuana flower buds (76 per cent vs 27 per cent). It is also absorbed much more quickly (seconds vs minutes), producing a more intense euphoric high. Swiss researchers noted that as a result, dabbing provides an easier way of quickly consuming massive doses of THC that is more likely to lead to tolerance and withdrawal symptoms. A 2017 study in Drug and Alcohol Dependence of 121 recent BHO users reported higher levels of physical dependence, impaired control, academic and occupational problems.

In the meantime, the CDC in the States has advised against any vaping of THC-containing products at present. Even for those who are vaping only nicotine, caution is advised because stronger evidence is needed before any definitive statement can be made as to whether e-cigarettes are effective in helping smokers quit.