Bronchiolitis obliterans, or popcorn long as it is colloquially known, is an incurable condition that occurs when the bronchioles in the lungs are scarred due to the chemicals inhaled. Damaged bronchioles cause an overall reduction in lung capacity. The only possible treatment for popcorn lung is a lung transplant.
The National Institute of Health listed the following chemicals known to cause lung irritation and potential bronchiolitis obliterans when inhaled: ammonia, chlorine, welding fumes, diacetyl and oxides of sulfur and nitrogen dioxide. Respiratory infections can also lead to popcorn lung.
Without conducting surgical lung biopsy, it’s not possible to perform a reliable diagnosis, hence why research on popcorn lung is limited – even a lung biopsy doesn’t always return conclusive results. E-liquid flavoring factories have carried out studies, and it’s apparent that flavoring chemicals such as diacetyl can cause lung damage to some degree, although in not every case was the damage permanent.
Not to mention, BO has similar symptoms to chronic obstructive pulmonary disease (COPD), which occurs far more regularly, often in long-term smokers. So there’s no way of truly knowing how big an issue BO is. The onset of COPD is slow, taking years, whereas BO usually develops in just months – that makes it a bit easier to distinguish between the two. COPD is a mix of two common smoking diseases, bronchitis and emphysema.
Where does ‘popcorn lung’ come from?
The inhalation of diacetyl, chemically known as 2,3-butanedione can lead to popcorn lung. A flavoring agent, diacetyl was formerly used as a microwave popcorn additive until its dangers came to light in 2002 from the Centers for Disease Control and Prevention (CDC). A Missouri popcorn factory which used diacetyl had eight cases of bronchiolitis obliterans among employees from 1992 to 2000.
The earliest unconfirmed lung disease linked to diacetyl may come from a baking factory in 1985 when a case of BO was reported, according to the National Institute for Occupational Safety and Health (NIOSH).
Diacetyl sounded the alarm for dangerous flavoring agents, and hundreds of similar incidents across the U.S. have been followed with hundreds of lawsuits, the majority of which factory owners have settled out of court. A consumer who claimed his lung damage was caused by the diacetyl in his microwave popcorn managed to win millions in a suit, but sketchy science far from confirms that consumers were ever at risk from the diacetyl in the finished product.
Inhaled diacetyl has, however, been directly linked to bronchiolitis obliterans by multiple studies. Action has been swift, with microwaveable popcorn manufacturers wising up and taking diacetyl out of their products altogether. Meanwhile, government guidelines for how diacetyl should be used in the workplace have been set to help protect employees.
What is diacetyl?
Diacetyl is a chemical part of the diketone family. Best-known for their use as flavoring agents, all but one diketone is regarded as safe for ingestion. But worryingly that diketone is genotoxic acetylacetone, not diacetyl. The Missouri employees are proof alone that the inhalation of diacetyl is not safe, especially in a factory environment where workers deal with large amounts. Furthermore, acetyl propionyl (AP) or 2,3-pentanedione, a diketone with a familiar chemical structure to diacetyl, is thought to be dangerous too
The two are commonly found in process foods to provide an artificial creamy flavor. Diacetyl and AP are used in vegetable oil margarines, to create a buttery taste in what would otherwise be a flavorless product. Both diketones can also be used as sweeteners.
Aceotin (3-hydroxybutanone) has similar flavoring agent uses to diacetyl and acetyl propionyl but is part of the ketone family, not the diketone.
What connection do these compounds have with vaping?
Diacetyl, AP or a mixture of the two are found in some e-juice products. Of course, flavoring companies didn’t set out to intentionally harm consumers – when they developed their agents, there was no reason for inhalation to be considered. And when vaping first started, e-liquid manufacturers were inexperienced and never carried out ‘background checks’ on the ingredients they used.
However, savvy vapers did spot the risks with diacetyl, understandably since smokers looking for other options obviously would want to know if they were safe. Diketone concerns have been raised by forum members since 2009. Some argue that it doesn’t matter if diacetyl poses a minor threat as vaping is still far safer than smoking. More progressive vapers, however, are keen to come up with a better e-liquid ‘recipe’ without diacetyl or AP.
Vapers stunned by study highlighting flavoring agent risks
An accidental discovery from Dr Konstantinos Farsalinos in 2014 uncovered that diacetyl and AP was used in more e-liquids than anyone previously thought. The Greek cardiologist, who is respected in the vaping world, found that more than 70 percent of the e-juices he was using in a different study contained diacetyl, acetyl propionyl or both. And in high amounts too – nearly half of the tested e-juices broke workplace safety limits. The study stunned vapers who had no idea diacetyl and AP use was so prevalent.
Dr Farsalinos concluded his study showed vaping was a reduced-risk alternative to smoking, but that that vaping could do more to lower that risk further in their industry. So, in a nutshell, vaping and e-liquid products are safe, but if they could be even safer they should be.
Vaping community undecided on safe diacetyl and AP levels
Many in the vape community are in agreement with Dr Farsalinos, and have vociferously campaigned to e-juice manufacturers to find substitutes to diketones.
Others are more relaxed about diacetyl and AP, claiming that companies had changed their e-liquid ingredients, generally offering little proof. Therefore, the diacetyl issue still bubbles away, with sceptical vapers unsure as to whether companies have really taken the necessary steps to ensure diketones don’t end up in their products.
Is it financially sensible to test for diketones?
Testing for diketones is difficult because the quantities found in e-liquid products are so small – they were missed when early lab testing was taking place because detection limits were too high. With lab testing being expensive, and diketone levels clearly being so low, it’s fair to ask if it’s worth testing each batch of e-liquid for diacetyl and AP before it hits the shelves.
The limited research on inhaling diacetyl and AP means the industry cannot set standards on safe levels anyway, rendering lab test results somewhat meaningless. By and large, vaping consumers are aware that the act is much safer than smoking, and for mot that’s enough. Small e-liqiuid manufacturers would struggle to get into the market if they had to fork out for costly testing, especially if they made the formulas and knew no diacetyl or AP was used.
However, worried vapers have no reason to be, as market forces have worked. A section of the community demanded action, and diketone-free e-juices have promptly arrived. Testing is now a priority for serious companies, and the best brands are very open about their results.
Smoking and popcorn lung
Diacetyl and AP are found in high quantities in combustible cigarettes, 100 times more than in vape products, but no confirmed link has been made between smoking and bronchiolitis obliterans, or popcorn lung. Yet no smoker has even been diagnosed with popcorn lung, which could be quite revealing.
If smokers, who consume far more diacetyl than vapers ever would haven’t ended up with popcorn lung, then the chances that a vaper could are next to nil. Unfortunately, there haven’t been enough studies on the lungs of smokers who have died from various obstructive lung diseases, so we can’t conclusively determine the impact of diacetyl. We just know that, as always, smoking is more dangerous than vaping.
It’s impossible to get an accurate popcorn lung diagnosis without an expensive and tricky lung biopsy that may end up a waste of money. With popcorn lung and COPD treatments very similar, it’s not really worth finding out exactly why somebody ended up with the disease.
Therefore, it’s very easy to misdiagnose in this area, and smokers diagnosed with emphysema or COPD may really have popcorn lung, but we just don’t know it. Everyone knows that smoking is bad, so there’s no financial merit at this point in highlighting every single smoking disease – medical professionals have bigger priorities, in terms of money and time than this. As far as most doctors are concerned, if it looks like COPD it probably is.
Some of the Missouri factory workers were smokers; however the CDC determined that it was the diacetyl from the factory that had caused BO, not the diacetyl from long-term smoking. Their final analysis decided that when studying the medical evaluations of affected smoking employees, it was unlikely that the “severe fixed airways” obstruction was caused by smoking cigarettes.
Popcorn lung: should vapers worry?
If you’re a vaper reading this and finding out about diacetyl and AP for the first time, you understandably may be concerned or at the least confused. The truth is that vaping research is still in its infancy, making it hard to be definitive on vaping science. But we can exercise common sense and make a few safe assumptions about vaping and popcorn lung.
COPD in smokers has been ever present, but there has been no uptick in bronchiolitis obliterans recorded in vapers, and vaping has been around a while now. Anti-vapers are always going to cling to bad news in the media, and tobacco control supporters will never accept vaping as they don’t believe in harm reduction. But it’s all hot air – no report has made the link, and that’s what matters.
When the Missouri factory workers were exposed to diacetyl, the cases developed in just a few months. In more than a decade of vaping, there has been nothing comparable. In the future, if a vaper is diagnosed with popcorn lung, then it would be interesting to see their smoking history. But that’s a worry for then, not now.
It all boils down to this: compared to smoking, vaping is safe
For smokers trying to quit, vaping is a happy middle ground that’s predominantly safe. Of course, for a non-smoker, not vaping is going to be healthier than vaping, but they aren’t the target audience. Medical professionals and public health agencies are cottoning onto this, now advocating e-cigarettes to smokers over patches – this happened just recently with the ‘Stoptober’ campaign in the United Kingdom.
So if you like to vape nicotine e-liquid or CBD vape juice, then don’t let this put you off. Think of it this way: vaping’s detractors are always trying to find dangers with vaping, and they always come up with nothing. The evidence we have has found no connection with vaping and popcorn lung. That said, it would be great if all e-liquid manufacturers could take diketones out of their formulas.