"Smoking excessive amounts of tobacco has also led to poisoning; a case was reported where two brothers smoked 17 and 18 pipes of tobacco in succession and were both fatally poisoned."
"The estimated lower limit of a lethal dose of nicotine has been reported as between 500 and 1000 mg.". To get directly hurt by nicotine available in consumer products, you'd have to either drink up 20 bottles of high-nicotine-concentration e-cig liquid or be an infant.
That case you quote (surrounded by the context which says that you can't get serious nicotine poisoning from smoking in any reasonable way) is equivalent to drinking up 10+ liters of water in succession, at which point you also die.
But, Death is not the only harm. Kids have gotten series nicotine poising from smoking less than a pack. It's only fatal poisonings that are rare. "The initial symptoms are mainly due to stimulatory effects and include nausea and vomiting, excessive salivation, abdominal pain, pallor, sweating, hypertension, tachycardia, ataxia, tremor, headache, dizziness, muscle fasciculations, and seizures.[4]"
Sure, being stuck near an e-sig users may only cause a massive headache, nausea, and a case of the shakes, but that's still not OK.
Let me illustrate what I mean:
> "The estimated lower limit of a lethal dose of nicotine has been reported as between 500 and 1000 mg."
The highest commercially-available concentration of nicotine in ready-to-vape e-juice is 36mg nic/ml. This is considered extremely high nic, and is rarely purchased anymore. So, if you drank 14-28ml of this juice straight from the bottle, that might be a lethal dose (typical bottles are 15-30ml). I can think of several substances you likely have in your house today that have similar levels of toxicity.
My e-cig is loaded with 1.5mg/ml or 0mg/ml juice depending. I vape ~3ml/hour at full-bore. If I absorb only 50% of the vaporized nic, I am releasing 2.25mg of nic into the air over an hour. At 2 puffs per minute that's 0.02mg per puff, distributed over the volume of the vapor cloud.
If you walk through my vapor cloud on a sidewalk, your nic exposure is truly insignificant.
I -- and all friends I have who also vape -- make it a point to not subject others to our habit, out of simple human decency. But let's be real: you're far worse off walking by an idling car than you are walking through a single vapor cloud.
However, your friends are not the only smokers. A doorman may be slightly down wind of a 'smokers area' which get's a long swath of people over the day. Sure, he might get 0.1mg per smoker but multiply that by 200 people who go out twice a day and that's 40mg which is probably not lethal but still plenty to cause issues. Not to mention withdrawal issues on his days off.
In terms of e-sigs, the second hand dose is likely lower. Assuming the unregulated doses are as described. But, if people assume a poorly ventilated break room is ok then people who work next to it may also get a fairly high dose.
This volume increases by the third power of distance--give or take a factor of 3 depending on wind strength and direction, it'll roughly be a cone of sorts.
So start with the quoted-above 2.25mg per hour of "in your face" nicotine, which we'll assume you could ingest if you keep breathing within a cubic foot (0.028 cubic metre) of a single smoker's mouth for the entire hour.
Say the doorman is standing 25m (~80ft) away. (if he lets a crowd of smokers gather much closer to his door, he's not really doing his job properly)
So that's distance times 80, meaning volume times 512,000. But it's a wispy wind-blown cone gushing in the specific direction of our poor doorman, so divide by 3, is 170,000 times the volume.
THEN, you multiply by the busy number of 200 people that are there all the time (very busy smoker's spot, this).
I get 2.6µg per hour. But only on the days when the wind has it in specifically for him. Standing within 25 metres from a crowd of 200 people constantly smoking e-cigs all day.
Case two, people thinking e-sigs are 100% safe and smoking inside.
In both cases each persion thinks there harm is meaningless but they add up.