The CDC has posted a MMWR report on the 2019 spate of serious lung injuries reported as a consequence of vaping. The first culprit to hit the news was vitamin E, it turns out this is not a unique factor after all.

Schier and colleagues report: No consistent e-cigarette product, substance, or additive has been identified in all cases, nor has any one product or substance been conclusively linked to pulmonary disease in patients. authors identified lipids within alveolar macrophages from the three bronchoalveolar lavage (BAL) specimens stained with oil red O. All five patients reported using marijuana oils or concentrates in e-cigarettes, and three also reported using nicotine (3). In a report describing the clinical course and outcomes of six patients from Utah, health care providers described the potential diagnostic utility of identification of lipid-laden macrophages from BAL specimens (4). Among the 53 cases from Illinois and Wisconsin, however, the pathologic findings were heterogeneous. Whereas almost half (24/53) of these patients underwent BAL, seven reports described the use of oil red O stain that identified lipid-laden macrophages

Perrine and colleagues report: Among 514 patients with information on substances used in e-cigarettes, or vaping products, in the 3 months* preceding symptom onset, 76.9% reported using THC-containing products, and 56.8% reported using nicotine-containing products; 36.0% reported exclusive use of THC-containing products, and 16.0% reported exclusive use of nicotine-containing products. *erratum for the original which says “30 days”.

It’s frustrating that the takeaway message so far is that nobody knows if there even is a unique cause or set of causes for the recent spate of lung injuries. We certainly don’t know the cause. We probably don’t even know if the injuries *are* recently occurring or have always been a consequence of vape device use that simply wasn’t connected to the e-cigarette device use. We know how long it took to recognize that cannabis was causing a hyperemesis syndrome, after all.

My suspicion at the start was that it wasn’t anything to do with cannabinoids, specifically. This reported diversity would appear to confirm that. It always seemed more likely to me that if there was a unique cause that appeared to be associated with cannabis vape cartridges that this is a classic case of a third variable. Perhaps a new vehicle constituent or an extraction method that was being used only, or primarily, with cannabis vape preparation. Well, clearly even that is not the case since there seem to be some nicotine-only users who have experienced lung injury.

Keep your eye on PubMed for updates on this health crisis.

Schier JG, Meiman JG, Layden J, et al. Severe Pulmonary Disease Associated with Electronic-Cigarette–Product Use — Interim Guidance. MMWR Morb Mortal Wkly Rep 2019;68:787–790. DOI: icon

Perrine CG, Pickens CM, Boehmer TK, et al. Characteristics of a Multistate Outbreak of Lung Injury Associated with E-cigarette Use, or Vaping — United States, 2019. MMWR Morb Mortal Wkly Rep 2019;68:860–864. DOI:

Erratum: Vol. 68, No. 39. MMWR Morb Mortal Wkly Rep 2019;68:900. DOI:

By now most of you are familiar with the huge plume of vapor emitted by a user of an e-cigarette device on the streets. Maybe you walked through it and worried briefly about your second-hand vape exposure risk. Some of you may even have been amused to hear your fellow parents tell you with a straight face that their kids “only vape the vehicle for the flavor”. Sure. Ahem.

Nicotine is one thing, but there is also a growing trend to use e-cigarettes to vape marijuana and, allegedly, stimulants such as flakka (alpha-PVP).

As with many emerging drug trends it can be difficult to put solid, peer-reviewed epidemiology on the table to verify these behaviors.

A recent paper reports on some initial estimates on practices among middle- and high-school students.

High School Students’ Use of Electronic Cigarettes to Vaporize Cannabis. Morean ME, Kong G, Camenga DR, Cavallo DA, Krishnan-Sarin S. Pediatrics. 2015 Oct;136(4):611-6. doi: 10.1542/peds.2015-1727. Epub 2015 Sep 7.[PubMed]

The authors surveyed 5 High Schools and 2 middle schools in Connecticut in the spring of 2014. Apparently insufficient middle school data were obtained so the paper focuses on the high school respondents only.

There were three key questions for the purposes of assessing behavior rates. Students were classified as “never used” or “lifetime used” (for ever having tried at least once) for e-cigarette use, for cannabis use (any method) and for cannabis use with an e-cigarette device.

Out of the total sample of 3847 HS students who completed the entire survey (52% female), about 5.4% had used an e-cigarette to self-administer cannabis. If, however, the sample was limited to those who had ever used an e-cigarette, then 18% had used one to administer cannabis. For lifetime cannabis users, it went to 18.4% and for dual e-cigarette and cannabis users, 26.5%.

So while the majority of high school students who have ever tried cannabis have never tried using an e-cigarette to dose themselves, 20% is a sizeable minority.

As always, it will be most interesting to see where these trends go and how they extend to older user groups. It could be that it is something that kids try and abandon (perhaps due to not learning different inhalation topography necessary for the desired high as with nicotine). It may be that older users are loathe to change their established patterns or see no advantages to e-cigarettes. I anticipate that solid data on these trends will be slow to emerge but I’ll be keeping an eye out.

Relatedly, the research community has been responding to this trend, and I wanted to draw two new papers to your attention.

Marusich and colleagues report from the Wiley group at RTI that they have a new model of flakka (and methamphetamine) delivery that increases locomotor activity and induces place preference in mice.

Pharmacological Effects of Methamphetamine and Alpha-PVP Vapor and Injection, Julie A. Marusich, , Timothy W. Lefever, Bruce E. Blough, Brian F. Thomas, Jenny L. Wiley, 2016, Neurotoxicology, doi:10.1016/j.neuro.2016.05.015

Nguyen and colleagues report from the Taffe group at TSRI that they have a new model of THC delivery that induces hypothermia, hypolocomotion and anti-nociception in rats.

Inhaled delivery of Δ9-tetrahydrocannabinol (THC) to rats by e-cigarette vapor technology, Jacques D. Nguyen, Shawn M. Aarde, Sophia A. Vandewater, Yanabel Grant, David G. Stouffer, Loren H. Parsons, Maury Cole, Michael A. Taffe, 2016, Neuropharmacology,doi:10.1016/j.neuropharm.2016.05.021