No one vapes 100mg nicotine. It doesnt quite work that way.. Lessifer already hit it, its purpose is to dilute it down with more PG and VG. Its a volume measurement, that single bottle by itself is 100mg/ml of nicotine sure, but add more volume to it, and it goes down quick. I buy 100mg nic in 120ml bottles but I make juice in 60ml batches at a time at 6mg of nic with a 50/50 PG/VG ratio. That means that Im only using 3.6ml of that 100mg nicotine per each 60ml flavor, and the rest of that 60ml is made up of straight PG, VG, and the flavorings which are also PG based. When factored in with the rest of the ingredients that make up my 60ml batch means there is only 6mg/ml of nicotine in it.
And like VHRB2014 just said, if youre sensitive to it, you better take extra precautions.. Im sloppy, Ive gotten it on me before and had absolutely nothing happen to me. Granted I used to use it to put a stop to red ant hills in my front yard before (it works awesome), but from getting "slop" on my fingers and hand during juice making, I havent even got a head rush from it yet. If you spilled a whole bottle on you, Id worry but just be careful like you should be and youll be fine.