So, physiological pH is around 7.4
I doubt that any amount that you could take into your lungs would be sufficient to alter the homeostatic mechanisms that keep the body at 7.4. Most likely, there wouldn't be enough vapor to even affect the pH of the lungs. There was a short conversation in the
THR facebook group in which Konstaninos Farsalinos said that the pH of the liquids he tested was around 8.5, and he and Carl Phillips seemed to agree that decreasing the pH would increase nic absorbtion, but that the vapor would be diluted and end up at about 7.4.
So, I can't imagine small changes in pH having effects on your whole body pH. BUT, If people go for more extreme acidity or alkalinity to try and make it so, there is the potential for cell damage. I have no idea what the range is that the lungs couldn't buffer to ~physiological. But there has to be a point where the lungs couldn't. Think of inhaling bleach fumes - the reason bleach works is because it's alkalinity (~12.6), but it's not exactly healthy for cells.
Atty, this is a flyby and i didn't read the links yet- so i dunno if this is what you were asking about, or whether i got the context of the discussion right. If people really are changing the pH to any extremes, i'd suggest it be moved to the not advisable subforum.