

TL;DR: Small study of only 3 out of 100 brands on the market, so limited inference can be drawn but cheap construction leaches toxic substances into the liquid in ways that older non-disposable vapes don’t. In terms of health risk non-disposable vapes are best followed by a tie between traditional cigarettes and disposable vapes.
The fundamental flaw with the phone system is it’s all or nothing. It’s difficult to get in, but once you’re in there’s zero controls (DNS used to and somewhat still does also suffer from this).