A recent Harvard study looked at the presence of diacetyl in vaping liquids and its potential risk. While the study, though limited, was valid, there has been some media over-reaction and misinformation about the issue. The concerns arose in 2002 when the Center for Disease Control documented some cases in bronchiolitis obliterans, colloquially known as “popcorn lung,” in workers at a popcorn factory. Diacetyl, because it tastes like butter, is commonly used in powdered form to give microwave popcorn its butter-like flavor. You might also find it in butterscotch candy. No adverse health effects have been seen when the additive is ingested (nobody has ever gotten respiratory illness from eating too many hard candies), the danger is present only when inhaled over a prolonged period of time at very high levels of exposure.
In the cases documented by the CDC, some workers contracted this dangerous disease by being exposed to diacetyl in powdered form on the factory floor for extended periods of time. Microwave popcorn manufacturers have since eliminated the chemical from their product.
What the Harvard study says – and what it doesn’t
The study looked at a sample of 51 e-cigarette products for the presence of diacetyl, as well as 2,3-pentanedione and acetoin. Diacetyl was detected in 39 of the 51 flavors tested. Of those 39, there was one outlier which registered 239 micrograms per e-cigarette, while the rest ranged from having only trace amounts below the study’s Limit of Quantification (LOQ), to 38.4 micrograms, with an average of about nine micrograms when the outlier is excluded.
The study does not conclude however, that there is a link between diacetyl in vape liquids and popcorn lung disease, it merely notes that popcorn lung has been seen as a danger when inhaled in particulate form on the factory floor. When the CDC first noted the incidence of popcorn lung, diacetyl was measured in the air on the shop floor at 18 parts per million, and the disease was contracted after prolonged exposure to that high level. According to the report, the factory’s process generated visible dust and aerosols, with the highest incidence of illness seen in mixers and packaging workers who were in direct contact with the mixing tanks.
It should be noted that any diacetyl exposure in vape shops would not compare and the CDC study notes that, “We evaluated concerns about exposure to vaping-related chemicals in a vape shop. Exposure to flavoring chemicals (diacetyl, 2,3-pentanedione, acetaldehyde), formaldehyde, nicotine, and propylene glycol were all below occupational exposure limits.”
Ultimately the study did not make a direct connection between vape juice containing diacetyl as a flavoring agent, and respiratory illness. It did conclude that further study is needed, which is a reasonable position.
Diacetyl levels compared
To bring diacetyl levels into perspective, consider a recent study that detected diacetyl in combustible cigarettes in the range of 301 to 433 micrograms per cigarette, many times greater than that contained in some vape juices.
This is in line with FDA and CDC studies which show that in general, vaping is safer than smoking combustible cigarettes. While neither agency endorses vaping, both do acknowledge, along with the American Cancer Society, that the carcinogens contained in cigarette smoke pose the greatest danger, and those same carcinogens do not get imparted in the vapors generated by e-cigarettes.
Those agencies, and many responsible clinicians, are also beginning to acknowledge that vaping is an acceptable and very effective tool that can be used for those who wish to quit smoking. Diacetyl may well be a concern, but as with the carcinogens contained in combustible cigarettes, less is always going to be better – and vape juices consistently contain less diacetyl than do combustible cigarettes.
Not all e-liquids contain diacetyl
Even though the Harvard study is inconclusive, it does pay to be aware, and there are plenty of e-liquids on the market which are diacetyl-free. Vapor Authority carries several of these, including the Halo brand, which maintains a professional laboratory and tests all products diligently, and does offer a variety of flavors while keeping the diacetyl additive out of all of their products.
The research is clear – smoking combustible cigarettes causes cancer, and switching to e-cigarettes reduces that risk. Diacetyl may pose a risk, but the amounts contained in e-cigarettes is lower than that in cigarettes, and many e-cigarette brands contain none at all.