US health officials have now confirmed there are 530 confirmed and probable cases and seven deaths from severe lung-related illnesses tied to vaping, and there are no signs that the outbreak is easing.
The Centre for Disease Control (CDC) and Prevention is looking closely at the different flavoured nicotine juices and other substances users may be vaping in e-cigarettes to determine how the aerosol might be affecting users’ lungs.
The mystery and concern remain. And, many smokers who use these devices to quit are concerned that a valuable tool may be taken away from them.
There’s much more that researchers need to know. These devices have a short history. As an engineer who studies how people use tobacco products, I believe that users’ behaviour is key to understanding the positive and negative health effects resulting from e-cigarettes. After all, their intent was to help people stop smoking, the number one cause of preventable death in the US.
The way users puff, how long they puff and what they puff all play a role. We do not yet know how this behaviour affects how much of each substance vapers consume over the course of their daily lives, but we have reason to believe it is significant.
Many are sceptical that e-cigarettes will reduce death rates related to smoking. Historically, safer cigarettes have not delivered on a similar promise. After the US surgeon general declared smoking harmful in 1964, smokers who could not quit migrated to what were then considered low-yield cigarettes, marketed as safer and having less tar than regular cigarettes.
But the wide use of low-yield cigarettes did not lower death rates for smokers. Cases of squamous cell lung cancer did decrease after the surgeon general’s warning, but another type, adenocarcinoma, increased.
Engineering models suggest that changes in smoke characteristics combined with smokers’ compensating behaviours changed where the particles deposited in the lung played a role. Smokers may have consumed more smoke to maintain their addiction. Different cancer types originate in different lung locations.
The thought is that smokers changed their behaviour, and in doing so, may have traded one type of cancer for another. Traditionally, cigarettes were tested in a laboratory, using smoking machines - not a smoker - using an industry standard protocol established in 1966. Research later revealed that this “mechanised smoking” did not represent realistic behaviour and so did not represent realistic exposure to harmful constituents.
Researchers are applying lessons learned from the low-tar debacle and generating scientific evidence to understand the true health impact of e-cigarettes.
Since e-cigarettes entered the market in Europe in 2006, demand increased from those hoping to quit cigarettes to those who have never smoked, including an unusually high number of young people. This has raised concerns. Is vaping a gateway for youth to start smoking?
In June, the Food and Drug Administration released guidelines for e-cigarette manufacturers, recognising the significant role behaviour plays in determining whether or not a product poses a health threat. The guidelines call for an assessment of how individual users consume the product, including such things as the number of puffs, puff duration, puff intensity, puff duration and the frequency of use.
This behaviour data is very important for many reasons. Users may adopt a behaviour that nullifies any anticipated health effect based on lab tests.
A puff generated in the lab may contain less nicotine, but the user may simply take more puffs during the day to achieve their nicotine addiction, and so consume more toxins than expected.
Researchers and physicians also need to know what substances are being vaped and also various device designs. The FDA maintains a list called harmful and potentially harmful constituents, based on data related to traditional cigarette smoking, but less is known about the effect of product designs. Users can tamper with the various modular devices, which could change their effects. Teens may be particularly likely to toy with devices.
The FDA is updating the list to include ingredients that might be found in e-cigarettes.
Nicotine is already on the list, as well as various metals and other non-nicotine substances.
The liquids used to deliver the nicotine could be a problem. The base (e-liquids), typically made of a combination of vegetable gylcerine and propylene glycol, may alone cause an inflammatory response in the lungs, even if flavour additives are banned.
And with regard to flavours, it is important to understand that the toxicity of a substance may be different if it is inhaled versus ingested. For example, vanilla flavouring may be deemed safe for eating, but it may not be safe for vaping.
Some flavourings decompose when heated and generate molecules that are not in the base e-liquid.
Would reducing the intake of flavourings also reduce harmful effects?
And how much of these additives can be consumed before harmful effects materialise?
By re-enacting vaping behaviour in the lab, those of us who study design and behaviour can better understand the nature of the constituents being consumed. Puff flow rate alters the nature of the aerosol, so users can control the strength of each puff simply by altering the way they puff.
E-cigarette users change their puffing flow rate when they switch flavours or nicotine levels and are altering their exposure to harmful or potentially harmful constituents.
We and other researchers aim to continue studying how new e-cigarette products are being used so manufacturers can develop safer products, and the FDA can develop meaningful regulations, so the consumer, in consultation with their physician, can make informed decisions.