According to the CDC, there are reports of more than 1000 patients in the US with vaping-associated lung injuries, and 23 deaths have been confirmed. The median age of deceased patients is 49.5 years, while the median age of patients overall is 23 years. The first reported death occurred in Illinois August 23rd 2019.

Do any of the following three explanations for this outbreak have factual support?

  1. There is no outbreak. After the first death attributed to vaping, patients with lung disease were asked about their vaping history, whereas before they were not. This explains the rapid rise of reported cases in the last two months. There were similar cases all along, but hospitals changed the questions they asked.
  2. Vapers changed the vaping parameters after watching videos like this one (8 of the 10 most watched vaping videos on youtube are about vape tricks). During the hot summer months vaping outside, the viscosity of e-liquid was lower, introducing a second change that increased the substance intake through the inhaled aerosol.
  3. The onset of the outbreak was so rapid that no change in products, buying behaviour or vaping behaviour could explain it because these things happen over months and years, not weeks. The cause of the outbreak was a firmware upgrade in the vaping devices that led to a change in vaping conditions resulting in harmful substances created while vaping (for example in a vape dry hit).
  • 2
    Why just these three? What about the possibility that a new ingredient has been introduced to the vaping liquids? From what I've read, the CDC's suspicions are pointing toward flavoring agents.
    – Carey Gregory
    Oct 5, 2019 at 21:04
  • 1
    I'm sure there are plenty of ideas of what might be happening. A significant portion of affected people said they were vaping commercially available liquids, while the majority were vaping illicit THC-containing liquids. This new ingredient would have to appear in commercial as well as illicit sources at the same time to explain the outbreak. I don't know how many suppliers of glycerol and propylene glycol there are. If it were a single supplier, this could be the source of a new ingredient because at least one of these ingredients is present in almost all vaping liquids. Oct 6, 2019 at 1:05
  • 4
    I very much doubt self-reporting of illicit substances. I would expect that a substantial percentage of the users who denied illicit use were lying. But this is all speculative. I think it's a great question but I also think the investigation is too young to offer good answers.
    – Carey Gregory
    Oct 6, 2019 at 4:19
  • Another idea: cadmium in cheap vaping pens Oct 8, 2019 at 20:40
  • They have found high levels of vitamin E acetate in commercially available "thickening agents for vaping liquids" from 3 suppliers (see my answer).
    – Jan
    Oct 11, 2019 at 11:10

2 Answers 2


While it could still be a mixture of acute reasons: metals, dust, plainly unknown toxins; the underlying reason seems not to be that plant matter is vaped, nor that liquids are vaped.

It also seems not to be causal whether THC or nicotine are in most cases "associated" with the disease.

What the fast onset of this disease makes prudent: implicating either THC or nicotine is so highly unlikely as to be an irresponsible claim. It makes no sense to scare people into another moral panic when the exact same substances are tolerated for decades in anyone user when pyrolised (traditional smoking). Note though that adding anything, including THC, to stuff to be inhaled is not 'healthy' per se

What is currently is known is that vaping liquids can be much more dangerous than ordinary smoking.
But this seems to be caused by additives in uncontrolled, unregulated, often even black-market and refill products. And in these the most likely suspect substance of the now leading theory is:

  • Recent CDC laboratory testing of bronchoalveolar lavage (BAL) fluid samples (or samples of fluid collected from the lungs) from 29 patients with EVALI submitted to CDC from 10 states found vitamin E acetate in ALL of the BAL fluid samples. Vitamin E acetate is used as an additive in the production of e-cigarette, or vaping, products. This is the first time that we have detected a potential chemical of concern in biologic samples from patients with these lung injuries.

  • CDC tested for a range of other chemicals that might be found in e-cigarette, or vaping, products, including plant oils, petroleum distillates like mineral oil, MCT oil, and terpenes (which are compounds found in or added to THC products). None of these potential chemicals of concern were detected in the BAL fluid samples tested.

  • This is the first time that we have detected a potential chemical of concern in biologic samples from patients with these lung injuries. These findings provide direct evidence of vitamin E acetate at the primary site of injury within the lungs.

  • These findings complement the ongoing work of FDA and some state public health laboratories to characterize e-liquid exposures and inform the ongoing multistate outbreak.

Key Facts about Vitamin E Acetate

  • Vitamin E is a vitamin found in many foods, including vegetable oils, cereals, meat, fruits, and vegetables. It is also available as a dietary supplement and in many cosmetic products, like skin creams.

  • Vitamin E acetate usually does not cause harm when ingested as a vitamin supplement or applied to the skin. However, previous research suggests when vitamin E acetate is inhaled, it may interfere with normal lung functioning.

  • Vitamin E acetate is used as an additive in the production of e-cigarette, or vaping, products, because it resembles THC oil. Vitamin E acetate is also used as a thickening ingredient in e-liquids.

–– CDC: Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products (Updated November 8, 2019,)


There are some data about possible causes of vaping-related lung damage, the type of the damage and symptoms, but not about the changes in medical history questionnaires, vaping habits or e-cigarette firmware.

Most commonly associated substances were THC and nicotine containing oils. Most of the investigated samples contained very high amounts of vitamin E.


Tetrahydrocannabinol (THC)-containing oils (not smoking or vaping plant matter):

E-cigarette Product Use, or Vaping, Among Persons with Associated Lung Injury — Illinois and Wisconsin, April–September 2019 (CDC.gov, October 4th, 2019):

Overall, 75 (87%) of 86 interviewed patients reported using e-cigarette products containing tetrahydrocannabinol (THC), and 61 (71%) reported using nicotine-containing products.

enter image description here

Image: Brands of tetrahydrocannabinol and nicotine products reported by patients with lung damage

Mayo Clinic, October 2nd, 2019:

All of the patients (17) had vaped, and 71% had vaped with marijuana or cannabis oils.

Vitamin E acetate:

New York State Department of Health Announces Update on Investigation into Vaping-Associated Pulmonary Illnesses (September, 5th, 2019):

Laboratory test results showed very high levels of vitamin E acetate in nearly all cannabis-containing samples analyzed by the Wadsworth Center as part of this investigation.

and, according to governor.ny.gov:

...The Wadsworth Center has obtained samples of thickeners from these three companies and determined that they are nearly pure vitamin E acetate oil.

So, they have found vitamin E acetate in the actual vaping liquids used by the patients and in the thickening agents sold by 3 commercial suppliers.

Chemical injury of the lungs:

Mayo Clinic, October 2nd, 2019:

it seems to be some kind of direct chemical injury, similar to what one might see with exposures to toxic chemical fumes, poisonous gases and toxic agents.

Researchers found no evidence of tissue injury caused by accumulation of lipids — fatty substances such as mineral oils.

We were not surprised by what we found, regarding toxicity," says Dr. Larsen, senior author of the study. "We have seen a handful of cases, scattered individual cases, over the past two years where we've observed the same thing, and now we are seeing a sudden spike in cases.


CDC.gov, October, 3rd, 2019:

Patients in this investigation have reported symptoms such as: cough, shortness of breath, chest pain, nausea, vomiting, diarrhea, fatigue, fever, or abdominal pain that have developed over few days to several weeks.

A lung infection does not appear to be causing the symptoms.

In summary, the cause of vaping-related lung damage is still not known; the only unusual thing they've found so far are high amounts of vitamin E acetate in vaping liquids that probably came from thickening agents.

  • Ahm, could you clarify (quoting more about) how and which products were vaped? The plant matter could be vaped and does not contain these "high levels of tocopherol", was that added to the plant material, were oils used, liquids of completely artificial origin enriched with VitE? ("Adulterated hemp" would presumably cause damage if smoked as well?) Oct 10, 2019 at 9:46
  • Oh. These were all pre-filled cartridges of strange provenance? Then please update the language that neither smoking marijuana nor vaping plant matter was found so far to cause any of these problems? Oct 10, 2019 at 10:00
  • I added an image with THC and nicotine products used as reported by patients. They have found high levels of vitamin E acetate in "thickening agents" for vaping liquids from 3 producers AND in many samples of the actual vaping liquids the patients have used.
    – Jan
    Oct 11, 2019 at 11:04
  • Inverse mentioned myclobutanil (a fungicide). NBCNews has ordered some tests and found some myclobutanil in marijuana vapes. For now, I'm not adding this to my answer, because it has not been related to actual patients in 2019 (yet).
    – Jan
    Oct 11, 2019 at 16:45

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