Professor Joseph Allen, Harvard T.H. Chan School of Public Health
The e-cigarette has blazed onto the scene recently, and itís become a big hit. They work by using a heating element to boil or vapourise a nicotine-rich mixture, that's then inhaled. An added facet is that there are literally thousands of flavours, which are made by adding scent chemicals to the mixture. Why is it though, Harvard's Joe Allen is wondering, that some of these flavour chemicals are turning up in e-cigarettes but have already been linked to serious lung diseases? Chris Smith reports...
Joe - For over a decade weíve known about severe lung disease associated with inhaling flavouring chemicals because of workers in the popcorn packaging industry, many of whom develop severe and irreversible lung disease after inhaling these flavouring chemicals.
So our interest in this topic came from knowing this history of occupational disease for workers in the popcorn industry and then learning that there were over 7,000 flavours of e-cigarettes available to consumers. And we thought, and it turns out correctly, that these flavoured e-cigarettes would have a lot of the same chemicals that were of concern from the workers over ten years ago.
Chris - Tell us a bit about those workers and how that particular story came to light in the first place and what went wrong for them.
Joe - Sure. It was about in May of 2000 in the United States, 8 workers who worked at a microwave popcorn processing plant reported to have a severe and irreversible lung disease called bronchiolitis obliterans. It was investigated and determined that this was due to inhaling flavouring chemicals in their workplace.
So they would mix up butter flavour for the microwave popcorn product and then they would inhale the heated flavouring chemicals. The disease became known as popcorn lung because this is where it was first discovered in these workers, and what you have is virtually the same thing happening with flavoured e-cigarettes. You have a heating element heating the flavouring chemicals, and the consumer inhaling the chemicals.
Chris - And more critically, are they the same chemicals that you would find in a popcorn factory?
Joe - We found at least one in 92% of the flavoured e-cigarettes we looked at. IN particular, one of the chemicals that got the most attention, called diacetyl and we detected diacetyl in over 75% of the flavoured e-cigarettes we tested, and this is the chemical that in the United States the investigating agency said ďitís highly likely that diacetyl contributed to the occurrence of fixed obstructive lung disease, also known as bronchiolitis obliterans, also known as popcorn lung.Ē
Chris - Now tell us how you did this study first of all and then we can look a bit at what these chemicals are doing in these e-cigarettes, if theyíve already got this track record.
Joe - Sure. So, our study is very is a very simple design; we tested 51 flavouring chemicals Ė remember there are over 7,000 available Ė and we set up in my lab a system to mimic smoking or inhalation. So we pull out the chemical, just like a user would, and then we capture it on a sampling device and we analyse it according to standardised methods to look at three different flavouring chemicals so, diacetyl, acyteon and 2,3-pentanedione.
Chris - What do they smell like?
Joe - Well, this is whatís interesting about the flavouring chemical issue is that it first started, we first became aware of this in the popcorn workers and it was butter flavour, but these flavourings are not limited to just butter. In fact, diacetyl is used in wide range of flavourings like caramel, butterscotch, pina colada; all sorts of fruit flavours, banana, apple, grapes, strawberry. So these flavouring chemicals are widely used to flavour a lot of the food products we consume, and actually in our study we found diacetyl and other flavourings in flavoured e-cigarettes that we deem are appealing to children like cupcake and cotton candy flavour e-cigarettes.
Chris - I mean thatís a whole different ball game isnít it whether or not this acts as a gateway into smoking behaviour. But when you inhale these flavours from an e-cigarette, I think one critical question is, if you are going to link this to the same sort of damage that the popcorn workers got, is there evidence that whatís coming out of the vaporiser in an e-cigarette is going to be particles, which are the same sort of size, the same chemical characteristic, as those popcorn workers would have been breathing in in the factory?
Joe - Right. So this is one of the follow-up questions that weíre starting to look at and I know others are, but itís the characterisation of these at a bit finer scale. So we donít know much at all right now about the hazard associated with these flavoured e-cigarettes and that was one of our goals of our study, is to be sure that when we start talking about e-cigarettes and safety and risk, is that flavouring chemicals are part of that conversation.
Chris - To be clear here, youíre not saying these chemicals cause this lung disease, but what you are saying is thereís very strong evidence from other situations that there is a strong association between exposure to them and getting lung disease. Therefore, itís reasonable to be prudent and say there could be a risk here, we need to do something about this.
Chris - Thatís exactly right Chris. So this wasnít a study of a health effect, itís simply designed to show that we have the presence of these flavouring chemicals that didnít just cause minor diseases, they caused severe and irreversible lung disease in workers. We donít have the same kind of warnings or knowledge reaching consumers of flavoured e-cigarettes. Many of these consumers are children, and many of these flavoured eCigarettes that weíve shown in our study, we feel, are even marketed towards kids.
Chris - So what would you like to see change?
Joe - Well I think at a minimum we should be regulating e-cigarettes as carefully as we regulate cigarettes.