Variations in design

While all ENDS had a battery, atomiser and cartridge, design details of each brand differed (figure 1A). Battery length, cigarette colour and size of the air holes (not visible) near the red indicator light varied among brands. Manufacturers' names were printed on each battery, but it was sometimes difficult to distinguish between types of batteries within a brand. For example, the Crown Seven battery was not identified as the ‘Hydro’ model, and one Smoking Everywhere battery was not identified as the ‘Platinum’ model.

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Figure 1

Design and labelling of six models of ENDS. (A) All models have a battery, atomiser and cartridge (reservoir plus mouthpiece). The end of the VapCigs reservoir adjacent to the atomiser is sealed by foil. The Smoking Everywhere Platinum cartridge contains a disposable atomiser (arrow). Reservoirs vary in size with approximate volumes ranging from 386 mm³ (Liberty Stix) to 1176 mm³ (NJOY). Examples of wrappers containing replacement cartridges are at the far right. Most replacement cartridges come sealed in unlabelled wrappers and have plugs or caps covering the end that attaches to the atomiser. Smoking Everywhere Platinum was capped at both ends but not in a wrapper. (B–E) Labelling of packs of replacement cartridges showing minimal labelling on VapCigs pack (B), handwritten marks indicating flavour and strength on a Liberty Stix pack (C), more complete labelling on the front of a Smoking Everywhere pack (D) and very detailed labelling and warnings on the back of an NJOY pack (E).

Atomisers had threads that screwed into the battery at one end and a U-shaped heating element that inserted into the cartridge at the opposite end. Atomisers from Liberty Stix, Crown Seven, Smoking Everywhere Gold and VapCigs were similar in design, but differed in length. Atomisers were not labelled, and some were interchangeable among brands. The Smoking Everywhere Platinum atomiser came embedded in the cartridge and was disposable.

Cartridges consisted of a reservoir that holds ENDS fluid and a mouthpiece. Reservoirs, varied in size, were open only at one end, and generally had flat surfaces that allowed aerosol to pass around the reservoir and into the mouthpiece. When assembled, the atomiser tip projected into the reservoir. Mouthpieces were generally cylindrical (NJOY was tapered), had a small air hole at one end and were wide open at the opposite end which slid into (NJOY) or over (all others) the atomiser.

To prevent fluid from escaping, cartridges had plastic plugs or caps at the large open end, except for VapCigs which had reservoirs sealed by aluminium foil. The open end of NJOY cartridges had a small rubber cap which was covered by a larger plastic cap. Prior to smoking, the plugs/caps were removed, and for VapCigs, the foil was punctured by the atomiser when the cigarette was assembled. Replacement cartridges came in plastic wrappers, except for Smoking Everywhere Platinum, which had only plastic caps on both ends.

Nicotine

All brands were sold with ambiguous amounts of nicotine/cartridge. Nicotine was usually indicted by a number followed by ‘mg’ (eg, 24 mg). It was not clear if this was mg/cartridge or mg/ml. Values for nicotine ranged from 6 mg (NJOY) to 24 mg (Liberty Stix, Smoking Everywhere Platinum). Some cartridges claimed no nicotine (0 mg). Manufacturers used terms such as zero/no, low/light, medium, high and extra high to categorise nicotine strength. However, these terms usually referred to different nicotine concentrations when comparing across brands. For example, Liberty Stix high cartridges had 24 mg of nicotine, while Crown Seven Hydro high had 16 mg (table 1).

Labelling of cartridges

None of the cartridges was clearly labelled with the manufacturer's name, nicotine concentration, expiry date and flavour (figure 1A). Cartridges with no nicotine looked identical to those with high nicotine and were indistinguishable once removed from their wrappers or packs. Liberty Stix had the word ‘Liberty’ on a few cartridges. Smoking Everywhere Platinum had 16 mg or 24 mg stamped on cartridges with no indication of its meaning. The Liberty Stix, Crown Seven, Smoking Everywhere Gold and VapCigs cartridges looked similar and often could be interchanged among brands. The Smoking Everywhere Platinum starter kit was reported on its website and the starter kit case to come with high strength (16 mg) cartridges; however, the pack inside one kit was labelled ‘24 mg’.

Labelling of wrappers

Replacement cartridge wrappers were more informative than cartridges, although none clearly included the amount of nicotine and manufacturer's name (figure 1A). NJOY wrappers included strength (high, medium, low nicotine), flavour and expiry date. Smoking Everywhere Gold wrappers had flavour and a letter indicating strength, although labels were confusing (eg, ‘MIN Z’ or ‘TOB H’ or ‘Tobacco Original NO’). Crown Seven wrappers had strength (eg, ‘High’) with no indication of flavour. Only Crown Seven's assorted pack wrappers indicated the specific flavour with strength. NJOY, Smoking Everywhere Gold and Crown Seven wrappers were labelled with small stickers that could easily fall off. Only a few Liberty Stix wrappers had the word ‘Liberty’ typed out, and none indicated strength or flavour. VapCigs starter kits included cartridges without wrappers, while replacement cartridge wrappers were unlabelled.

Labelling of packs

Replacement cartridges are sold in ‘packs’, which had labels with more information than cartridges and cartridge wrappers. However, packs in general were not uniformly labelled within or between brands (figure 1B–E).

Except for NJOY and Crown Seven, no packs indicated nicotine concentration, although all manufacturers attempted to indicate strength (eg, high, medium, no nicotine) and flavour. VapCigs packs had only strength (on all packs) and flavour (some packs) plus the letters ‘VC’ to indicate brand (figure 1B). Liberty Stix packs had flavour and strength with a handwritten dot next to a checkbox (figure 1C). Crown Seven indicated strength with a handwritten dot and flavour with either a handwritten dot or a small sticker (not shown). Terminology was inconsistent on Crown Seven's packs. For example, one pack had a handwritten dot next to ‘espresso’, while another had a ‘coffee’ sticker. It was not clear if these were the same flavours. Although there was a checkbox for the Crown Seven ‘assorted’ pack, ‘assorted’ was handwritten on packs. The pre-printed choices on the Crown Seven packs did not fully correspond to choices on their website, and none of the Crown Seven packs indicated the cartridges were for the Hydro model only. Smoking Everywhere packs were not uniform in their design, information or colour (figure 1D). Smoking Everywhere Gold packs did not state that cartridges were for the Gold kit only, while Platinum packs had ‘Platinum’ on four faces. The Gold tobacco flavoured packs had a sticker on the back side stating the flavour and strength as ‘TOB H’ or ‘Tobacco Original NO’ which were confusing. Mint flavoured packs had ‘Mint’ on the pack faces, yet used stickers on the back to indicate the flavour and strength, and again the code was cryptic (eg, ‘MIN H’ or ‘MIN L’ or ‘MIN Z’). NJOY had strength and flavour directly printed on packs.

Liberty Stix and Smoking Everywhere Platinum did not list cartridge ingredients. Smoking Everywhere Gold, Crown Seven and our original packs of NJOY listed ingredients as nicotine, water, flavouring (not specified) and propylene glycol. Recent shipments of NJOY included ethanol, glycerol, acetylpyrazine, guaiacol, mysomine, cotinine and vanillin. All packs listing ingredients included nicotine, even zero strength packs. All packs (including zero strength), except Crown Seven and VapCigs, had some form of warning regarding nicotine. Only some Smoking Everywhere Gold packs had a Surgeon General's warning. NJOY packs indicated the FDA had not approved the product, whereas Crown Seven and Liberty Stix packs had no FDA information. Some Smoking Everywhere packs mentioned the FDA, while others did not. Finally, some packs (NJOY and Smoking Everywhere Gold) indicated that the product was intended for adults and not pregnant women, but only NJOY, which had the most complete warning information, indicated possible side effects that may accompany use (figure 1E).

Leakiness of cartridges

Cartridges from most brands leaked nicotine-containing fluid from their reservoirs (figure 2A–F). When cartridges were removed from ENDS after smoking, beads of reservoir fluid were left adhering to the surface and heater tip of the atomiser and to the cartridges (figures 2A,B). Moreover, unused replacement cartridges (eg, NJOY and Liberty Stix) sometimes had beads of reservoir fluid on their surfaces and inside the sealed wrapper (figure 2C,D). It was difficult to load such cartridges onto an atomiser without getting reservoir fluid on our hands and other surfaces. When plugs were removed, reservoir fluid readily leaked out and if placed on a table, pools of reservoir fluid rapidly accumulated (figure 2E,F). NJOY instructions state ‘Condensation and/or liquid may be seen inside the cellophane bag, which is a normal occurrence.’ Smoking Everywhere Platinum, which had a disposable atomiser embedded in the reservoir, and VapCigs, which had a reservoir sealed by aluminium foil, presented the least potential for direct contact between the user's hands and reservoir fluid when assembling the cigarette. However, after use, even these better designs left reservoir fluid on the atomiser.

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Figure 2

Leakiness of Liberty Stix and NJOY cartridges. (A–B) Show droplets of cartridge fluid (arrows) on the surface of atomisers after removal of a used cartridge. (C–D) Show fluid (arrows) inside the wrapper of unused cartridges. The NJOY fluid is brown-coloured. (E) Shows fluid (arrow) that has leaked from a fresh cartridge onto a counter top before the cartridge was assembled into the ENDS. (F) Shows fluid (arrows) on the surface of a fresh replacement cartridge and its cap before the cartridge was assembled into the ENDS.

Defective parts and operation

The NJOY kit arrived with dead batteries, which were quickly replaced. The red indicator tip at the end of the battery flashes a variable number of times if the battery is low or if the smoker is inhaling too many consecutive puffs. When ENDS were evaluated on a smoking machine, none of the flashing codes operated correctly all the time. Liberty Stix and VapCigs batteries were capable of lighting the red indicator light in the palm of our hands without the presence of an atomiser or cartridge. VapCigs released aerosol while held in our hands, apparently due to volatilisation of residual fluid on the surface of a new atomiser.

Disposal of spent cartridges

Cartridges stop producing aerosol after 100–200 puffs then need to be replaced by a fresh cartridge. Used cartridges contained liquid in their reservoirs (not shown). The amount of fluid left in spent cartridges was quite variable, with NJOY cartridges retaining the most fluid. None of the brands indicated a proper way to dispose of cartridges, wrappers, cartridge plugs, reservoirs, old batteries or old atomisers, and only NJOY and Crown Seven mentioned disposal at all in their instructions.

Errors in filling orders

Most errors in filling internet orders involved sending cartridges with the wrong strength of nicotine (eg, two of nine Crown Seven cartridges and two of 19 Liberty Stix cartridges were the wrong strength). Smoking Everywhere made numerous errors (eg, repeatedly sent the wrong kits and cartridges), and even after 6 months, their orders were not completely filled correctly. NJOY filled all orders without error.

Instruction manual

Instruction manuals were usually not complete and accurate. Instructions were specific for a brand, but not specific for the type of ENDS within a brand. For example, Smoking Everywhere's Platinum instructions included information for a different model (their ‘Mini Electronic Cigarette’). We evaluated the instruction manuals using a 100-point questionnaire (25 yes/no questions each worth four points) (table 2). Based on this questionnaire, NJOY had the best manual and VapCigs had the least helpful.

Truth in advertisement

On both websites and in print material, we found numerous statements regarding ENDS that were not based on scientific findings and for which there is no rigorous supporting data. Examples of such statements include: ‘Be careful to avoid inhaling any significant quantity of liquid. Although it gives you a slight tingling sensation, it is not harmful’ (Liberty Stix); ‘Within 2 weeks, your lung capacity will increase by 30%. Your energy levels will increase. Your throat and lungs will feel markedly better! Wrinkles in your skin will become less noticeable and colour will return to your skin’ (Liberty Stix). One pack (Smoking Everywhere) was labelled ‘Vitamin’, although no indication of what this meant was given.