If you notice the warnings concerning pets and PG, it has limits on ml/kg. It is also for eating the PG.
How much vapor do you think a 5 pound dog would need to inhale to equal the 100ml of PG that could give a dog an issue? And that dog would have to do that in a day as PG is moved out of the system fairly quickly.
So, if cats are more sensitive, which I don't know that they are, and that 5 pound cat would need to inhale 10ml of PG
through vapor in a day to get near the danger point?
There are lots of things that are dangerous. You can even die from drinking too much water. It is the concentrations of things that make them a real danger, not the thing themselves. Look up Phosphoric Acid and what it does to a body. Now look at the ingredients of your soft drink. Same deadly stuff, but bunches of folks drink it every day.
Will your cat get some nicotine, yep, a bit. Will it hurt the kitty? Very unlikely and I am sure the cat will give warning signs long before the danger level is reached. Just like us humans get headaches, hiccups, tummy aches as warning signs of getting too much nicotine well before we get close to the OD levels.
Unless you live in a sealed bubble with your pets, they will be getting small doses of quite a few toxic chemicals everyday. Some are natural, some are manufactured, but there are toxic substances everywhere.
It would make a good subject for a test kind of trial though, but I have no idea who would fund it.