PGA is pure grain alcohol, normally 190 proof everclear. In practical use, PGA is used at 5%, maybe 10%, maximum (too much and the liquid gets too thin for vaping).
A full carto is 1 ml, 2ml if it is a jumbo. 10% of 1 ml is 1/300 of an ounce. Call it equivalent to 1/150 ounce of 95 proof.
Even a heavy vaper only runs through around 5 - 6 ml in a full day (I know, I am one). That's under 1/25 of an ounce of 95 proof over a full day (> 12 hours of vaping), 1/50 of an ounce at the more normal 5% use. (And that's if you are only vaping VG juice that's cut with the maximum practical amount of PGA for thinning.)
Factor in the amount that's exhaled back out in the vapor and I don't sweat getting drunk on my eliquid.
(I DIY my own eliquid, it isn't used so much with PG liquids but is often used with VG ones, since VG is too thick and tends to mute the throat hit. I certainly wouldn't recommend DIY with PGA for a person new in recovery; plain grocery store distilled water can also be used to thin VG. After almost 24 years I'm so dry I fart dust
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