Smoking is not as simple as many assume. Smoking actually changes the disease risk profile a lot, lowering risk for many diseases. It's probably an open question if light smoking is even bad for you. Super centenarians have disproportionately been light smokers.
In no way is it an "open question' if "light smoking" is even bad for you: "light and intermittent smoking pose substantial risks; the adverse health outcomes parallel dangers observed among daily smoking, particularly for cardiovascular disease."
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.
Study of the regions of the world known as blue zones,[11] where people commonly live active lives past 100 years of age, have speculated that longevity is related to a healthy social and family life, not smoking, eating a plant-based diet, frequent consumption of legumes and nuts, and engaging in regular physical activity. In another well-designed cohort study, the combination of a plant based diet, frequent consumption of nuts, regular physical activity, normal BMI, and not smoking accounted for differences up to 10 years in life expectancy.[12]
Many centenarians manage to avoid chronic diseases even after indulging in a lifetime of serious health risks. For example, many people in the New England Centenarian Study experienced a century free of cancer or heart disease despite smoking as many as 60 cigarettes a day for 50 years. The same applies to people from Okinawa in Japan, where around half of supercentenarians had a history of smoking and one-third were regular alcohol drinkers. It is possible that these people may have had genes that protected them from the dangers of carcinogens or the random mutations that crop up naturally when cells divide.[15]
The results are sobering: "There is no pattern," says Barzilai, 54. "The usual recommendations for a healthy life -- not smoking, not drinking, plenty of exercise, a well-balanced diet, keeping your weight down -- they apply to us average people," says the researcher, "but not to them. Centenarians are in a class of their own." He pulls spreadsheets out of a drawer, adjusts his glasses and reads out loud: "At the age of 70, a total of 37 percent of our subjects were, according to their own statements, overweight, and 8 percent were obese; 37 percent were smokers, on average for 31 years; 44 percent said that they only moderately exercised; 20 percent never exercised."
But Barzilai is quick to point out that people shouldn't start questioning the importance of a healthy lifestyle: "Today's changes in lifestyle do in fact contribute to whether someone dies at the age of 85 or already at age 75." But in order to reach the age of 100, says the researcher, you need a special genetic make-up. "These people age differently. Slower. They end up dying of the same diseases that we do -- but 30 years later and usually quicker, without languishing for long periods."
37 percent isn't disproportionate. It is about average.
