Arthur a piece of advice. Don't believe everything you read.
Especially NOT if it comes from Wikipedia. (which this may or may not have done)
True a cigarette can contain the amounts you quoted (note - can - usually it doesn't)
The LD 50% in human is estimated to be around 50 mg ... estimated but never proven except...
Guess what? There are nicotine patches out there which contain 24 mg of nicotine. Now what does that mean? I slap a couple of those on you while you sleep and BLAM you die? Er... no. If that was the case people like the FDA would not let them out for people to play with...
Or consider this ... a batch of ground beef had been released which was contaminated with 300 mg/kg of nicotine. Sure it made some people sick... but no one died. If the LD 50% was 50 mg you would have seen several deaths. Particularly in children.
And yeah - picking tobacco actually makes some people sick under certain conditions, probably due to nicotine (nicotine transfers very well through skin... hence the nicotine patch!)
So... sorry your numbers are waaaaaaaaaaay off. I am not a fan of tobacco and I have grown cells under nicotine stress and I'd be the first to say it's not good for you, but there is no need to be an alarmist.
(BTW : LD 50% is the lethal dose which would cause half (50%) of a population to die).
Another funny fact - (which you should be aware of Arthur as I believe that it's a common thing in your part of the world) how much nicotine do you think people who *chew* tobacco get in their system anyhow? Tobacco paste (or whatever it's called) contains more nicotine than a cigarette, it doesn't get burned and... guess what? People don't die of that either!!!
So... yeah I would say don't smoke. It's bad for you. Heck we all know that - every smoker I have met knows that... But we have to die of something right?
(no I don't smoke irl but I don't have a problem with people who do so politely)