Ok I stand corrected. I've just finished giving your notion a good amount of research time
@BobCajun , and there's some validity to it. I was able to find an unbiased study (
https://www.jci.org/articles/view/128531) that indicated a disruption in macrohage activity with chronic exposure to VG/PG vapor. It doesn't dissolve the layer, as you said, but rather adheres to it. This slows down the lipid layer's ability to respond to infection and immune response as quickly and as potently.
It's worth noting that to get these results, mice were subjected to 24/7 vapor exposure. The earliest they began seeing a decrease in macrophage function while being exposed to the vapor 24/7 was 2 weeks. There haven't been any follow up studies on intermittent vaping, nor did I read anything in that study about how long it takes after you stop vaping to return to normal functioning.
I would agree with you that we should avoid PG/VG after learning this, but only in chronic users, like nicotine vapers. If you use a THC cart a few days a week for 5 minutes at a time, you will not experience what the mice experienced in the study, as your use time and frequency is a fraction of what it was in the study. 24/7 for 2 weeks vs. 5 minutes every 24 or 48 hours (depending on how one vapes). The concern for me is my friends who vape for nicotine uptake, not for THC uptake. These friends vape pretty consistently throughout the day. Not 24/7 obviously, but enough that it poses a risk imo. The study did note, however, that there was no inflammation, tar buildup, or cytokine response to PG/VG vapor, meaning it's less harmful in this regard than tobacco combustion. I guess people just need to make their own informed choices. Thanks for pointing out something I didn't know man.