I suggest being aware of the type of plastic the lids are made of. Many recyclable bottles are made of PETE and I suspect the caps are also.
https://en.wikipedia.org/wiki/Resin_identification_code
I learned the hard way that something seemed to degrade PETE. All of my base liquid stored in it ended up with a really bad plastic sort of aftertaste, which got worse the longer it sat.
I suspected the propylene glycol because of the wiki article. https://en.wikipedia.org/wiki/Polyethylene_terephthalate
Curiously, the original bottles that my nic and PG came in are PETE bottles, so it could have been the VG, which came in a HDPE bottle, which is what I use for my other storage methods. I have some other smaller bottles that are PETE that I havent had that problem out of but it may be that the plastic bottles used for drinks are processed differently. There was definitely some leeching going on with only a PG/VG base.
It probably wouldn't be a big deal for a one time use in a pinch, but personally, I would try to avoid it. I'm sure the heating doesnt help also, as previously stated.
Thank you for this. Not going to do it now.
No problem. I'm happy to give back to the community, even in minor ways like this. I had to find out the hard way, but hopefully this will save someone else the trouble and potential minor damages.
I had some swollen/backed up lymph nodes and ear infections for a few days, which I suspect had something to do with what is described in the safety section of that wiki article and was probably the process of cleanup after the fact. https://en.wikipedia.org/wiki/Polyethylene_terephthalate#Safety
I'm still not sure of exactly whats going on but I now know not to do it.
DO NOT DO THIS!!!!