The creativity of cannabis users leads to new methods of consumption. Although developments such as vaporisers, edible and liquid tinctures have become very popular alternatives to the traditionally smoked flower buds of cannabis, they show flaws in concentrations, contamination or efficiency over the day according to galenic forms.
Recently, consumption methods such as butane hashish oil (BHO, cannabis concentrate extracted with butane gas) called “dabbing”, have been increasingly observed, especially on Web fora. By eliminating tobacco and increasing THC levels, these optimisations appear to be interesting improvements for the therapeutic use and delivery of cannabis. However, public health concerns remain because of the ease of preparation, more rapid THC delivery (i.e., a potentially higher risk of dependence) and overdose.
Dabbing involves vaporising cannabis concentrates (BHO or cannabis dabs) at 300–400 °C on a hot surface and then inhaling the vapour through a specialised pipe7,8. BHO is a viscous, sticky to hard, wax-like concentrate that contains mainly acid cannabinoids and terpenoids. After thermal treatment, inactive tetrahydrocannabinolic acid (THC-A) is decarboxylated into psychoactive tetrahydrocannabinol (THC). BHO is highly enriched in THC, and its concentration is typically 15 to 30 times higher than that found in flower buds. However, the literature is very scarce concerning BHO preparation and composition. Commonly, a dab of the dense oil is placed on the end of a glass or titanium rod that has been heated. If the dab has been previously decarboxylated, the flame from a lighter is sufficient to vaporize the BHO, but if the dab has not been decarboxylated, a blowtorch is used to maximize the decarboxylation of THC-A into its psychoactive form, THC, and to vaporise the BHO concentrate.
Nevertheless, the enormous growth and development of electronic cigarettes (or e-cigarettes) have enabled the development of electronic devices exclusively dedicated to direct dripping (the liquid is dripped onto the bridge of the atomizer, instead of relying on the cartridge filler) and dabbing. These devices are currently available on the Internet and cannabis derivatives shops. Furthermore, a profusion of recipes is available on the Internet to prepare liquid refills enriched with cannabinoids. In this regard, BHO can be dissolved in the commercial liquids used to refill e-cigarettes, constituting an alternative to direct BHO dabbing. With the several thousand flavoured liquids commercially available, flavours added to liquid refills can mask the overwhelming typical odour of cannabis and can make its vaping more discreet.
Indeed, concentrating cannabinoids implies a concentration of terpenoids and odorant compounds, which renders dabbing an easily detectable method of cannabis consumption for people exposed passively to cannavaping. Other recipes mention mixtures of solvents and flavours elaborated according to home-made protocols, including the dissolving of BHO in various propylene glycol/glycerin mixtures, sometimes with the addition of edible or aromatic oils such as coconut or cinnamon. This new method of cannabis consumption could be called “cannavaping”.
Thus, “cannavaping” and BHO dabbing could be considered major risks of electronic device misuse mainly because of the uncontrolled cannabinoids compositions of liquid refills and dabs. Nonetheless, “cannavaping” (of liquid refills) with controlled cannabinoids compositions and concentrations offers a new opportunity to deliver therapeutic cannabis without the requirement of smoking. The regulations of European countries have recently registered positive concern with the therapeutic use of cannabinoids.
Nevertheless, the possibility of e-cigarette multiuse for cannavaping has arisen, whereas the carbonyls and volatile toxic compounds in the vapours of conventional e-cigarettes are still discussed. The multiple designs and settings at users’ disposal could lead to significant toxic compound levels even if it requires high settings, causing burnt off-flavours generally not appreciated by usual vapers, defined as vaping devices users. Indeed, to increase the decarboxylation rate of inactive cannabinoids acids (in case of misuse), cannavapers need to use high power settings (by using high voltage and/or low ohmic resistance atomizers).
Regular cannabis smokers will prefer e-cigarette aerosols with strong organoleptic qualities. Moreover, the unpleasant flavours of liquid refills heated at such high settings could be hidden by the strong flavour of cannabis terpenoids. Consequently, the investigations of e-cigarettes vapours should always consider carbonyls and volatile compounds monitoring. Although concerns about the generation of contaminants from glycerin and propylene glycol are well identified, other concerns that have received little attention until now include the potential for toxic effects from inhaled flavourings.