It gets absorbed very easily through the skin. The lethal dose is .5 to 1mg per KG of body weight so a 190 lb man would need to absorb 45 to 90mg of nicotine.
I'm not saying it doesn't get ingested easily, just that it has to get separated from the other eliquid ingredients and survive saliva and stomach acids to be absorbed, so that slows things down so you would need to take a lot to harm you (like 100drops of 24mg liquid to kill you). What we take in by accident from the cartridge is what... 2 or 3 drops, maybe? Pure nicotine is a different story and I'm sure a swig of that would kill you quick!
That makes sense. Saliva and stomach acid would probably break a-lot of it down. And the e-juice is certainly far far from being pure nicotine, so I certainly am not worried about a couple of drops here or there. But I'd definitely not say that it would be safe to ingest a whole 10ml bottle... Maybe someone can.. but I certainly won't