From what I understand, some vaping liquids contain diacetyl, the culprit in "popcorn lung".
[1] https://tobaccoanalysis.blogspot.com/2015/12/new-study-finds...
According to vape vendors in my country, it's not.
https://vapourium.nz/blogs/vaping-101/whats-the-story-with-d...
"Diketones such as diacetyl, acetoin and acetyl propionyl are present in a number of these flavourings as they add an authentic buttery and creamy taste to the e-liquids produced by many manufacturers."
The idea that conscious consumers reading ingredient labels will solve 100% of such a problem is also kind of silly. Look at the obesity problem as an example of how well labeling works - it's possible to read the labels and be careful about your food intake, but most do not.