Thalidomide is a good anti-nausea drug. Women who take thalidomide during pregnancy are at lower risk for nausea. Now, do you want to argue whether or not "light thalidomide" exposure during pregnancy is bad is an "open question"?
Because that's what you're arguing with nicotine, along with cherry picking questionable studies, moving the goal posts, and even linking to organizations associated with tobacco manufacturing.
Opioids have beneficial uses. So do you want us to think that it's an "open question" about whether "light intravenous use of heroin" as practiced is a good thing?
Did you actually READ any of the articles you linked? In almost every case you cite, mention is made of the overall risks of smoking ANY amount. In some cases, the articles aren't even talking about smoking - they are merely talking about nicotine in a variety of forms.
“Any smoking, even social smoking, is dangerous,” says David Wetter, Ph.D., chair of the Department of Health Disparities Research at M. D. Anderson. “Cigarettes and cigars are the only legal products whose advertised and intended use -- smoking -- will cause cancer and kill the consumer.”
And c'mon, really? Really? You cite a damned mouse study on carbon monoxide as that you think might be evidence that smoking might somehow, some way, be helpful...for...wait for it....heart attack and stroke? You cite a cell study that shows elevated levels of glutathione in smokers lungs and you want us to therefore magically jump to the laughable belief that smoking is therefore somehow good for your lungs? You cite a study that claims that rare thyroid cancer is reduced among smokers, when the likeliest explanation is that thyroid cancer is so rare that smokers die of other more common cancers and little things like strokes and heart attacks long before they can ever develop thyroid cancer.
Many of the other bullshit claims you cite above have been thoroughly debunked:
What's wrong with light heroin use? I doubt it's a problem. You seem like some sort of puritan.
I don't think much of anything you've said or linked has bearing on a cigarette a day in the context of a healthy diet. Are you as dogmatic about not living in cities? Because urban air pollution is a known stressor.
So now you're agreeing that known "stressors" like dirty air are in fact problematic.
Why don't you tell us more about the "open questions" of how safe dirty needles and dirty nicotine delivery systems are.
Now if you'll excuse me, you seem like someone uninterested in reason or in supporting your silly, shifting claims, and who is much more interested in rationalizing your own bad health habits.
http://onlinelibrary.wiley.com/doi/10.1046/j.1365-4362.2000....
http://www.data-yard.net/10v2/parkinson.htm
http://www.data-yard.net/30/asthma.htm
http://www.data-yard.net/10c/nicotine.htm
http://www.data-yard.net/10b/cm.htm
http://www.forces.org/evidence/files/brea.htm
http://www.data-yard.net/13/tlj.htm
http://rheumatology.oxfordjournals.org/content/32/5/366.abst...
http://www.ncbi.nlm.nih.gov/pubmed/3613836?dopt=Abstract
http://jap.physiology.org/content/63/1/152.abstract?ijkey=3e...
http://jnci.oxfordjournals.org/content/80/16/1329.abstract
http://onlinelibrary.wiley.com/doi/10.1111/j.1447-0594.2006....
http://cebp.aacrjournals.org/content/13/9/1444.full http://www.ncbi.nlm.nih.gov/pubmed?Db=pubmed&Cmd=ShowDetailV...