twice a day for just a month

It's empirical, but I've been vaping steadily all day every day since I switched from my 2 pack a day newport habit around 2013ish, give or take a year. Last time I went to the doctor he said I had the healthiest lungs he'd seen in a while.

I was as surprised as you are, frankly. Mostly because of the ports in the past but I guess it's been long enough since then to heal up my surfboard lung. I mean I did notice marked improvement in my ability to breathe about a month or two into the switch, and my ability to smell things came back shortly thereafter, and then the doc visit was years after that, so maybe I shouldn't have been surprised but I digress. In any case 2x daily for a month is pussy numbers, gotta bump those up, try 200 times a day for 10yr and your doc will say your lungs look great if they're anything like mine.

Well, I'm impressed they actually did test JUST the vape liquid, even though they're still calling them e-cigs.

Quoting from the journal itself:

There were no significant differences in changes of BAL inflammatory cell counts or cytokines between baseline and follow-up, comparing the control and e-cig groups. However, in the intervention but not the control group, change in urinary PG as a marker of e-cig use and inhalation was significantly correlated with change in cell counts (cell concentrations, macrophages, and lymphocytes) and cytokines (IL8, IL13, and TNFα), although the absolute magnitude of changes was small. There were no significant changes in mRNA or miRNA gene expression. Although limited by study size and duration, this is the first experimental demonstration of an impact of e-cig use on inflammation in the human lung among never-smokers.

The way I read this, it seems like there's a small correlation with inflammation, but there's no measurable risk of developing lung cancer from it (they were doing cancer research after all). Personally for an adult, I feel like "inflammation" is kind of a nothingburger, just stop vaping for a while and you'll be fine. But for kids developing habits, I can understand the concern.

That's certainly a problem. It's one of the big reasons I think THC vapes should be both legal and regulated. In the states were it is legal, there's strict inventory tracking every step of the way.

Admittedly it's a lot harder to get people on board with regulating drug-free vapes, but I think it would be a good idea to have guarantees about what you're consuming just like food.

The black market carts in question were specifically weed vapes, not nicotine vapes, which are actually more different than you may think. Not only was that not a problem with nic vapes ever, it hasn't been a problem with homemade weed carts since that one incident (which IIRC was caused by one singular dumbass in WI or MN) either.

There still are "black market carts" for both weed and nic, but they've learned not to use vitamin a and are now mostly just regular ol' knockoffs.

That said however, that's why it's always better to use a refillable vape with a bottle of juice over a disposable, they usually don't counterfeit bottles opting instead for dispos, and even if they did it's easy to make your own juice so you know what you put inside.

Our data suggest that the flavorings used in e-juices can trigger an inflammatory response in monocytes, mediated by ROS production, providing insights into potential pulmonary toxicity and tissue damage in e-cigarette users.

Well, I guess that's a point against flavored vapes. I really wish there were more studies, because presumably not all flavorings would have the same effect. A comparison with unflavored e-juice would have been great.