[DrThunder]

Excuse me? That's irrevocably false. Where did you pull that misinformation from? The big vape industry?

https://www.verywellhealth.com/what-is-nicotine-5075412

" There are many health risks and side effects associated with using nicotine. Some of the health risks include:

    Nicotine contributes to the development of emphysema—a type of chronic obstructive pulmonary disease— in smokers.
    It’s potentially carcinogenic. Chronic nicotine use is linked to lung, gastrointestinal, pancreatic, and breast cancer.
    Nicotine use is associated with peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). 
    Nicotine use increases the risk of hypertension and cardiovascular diseases.
    Nicotine use during pregnancy increases the likelihood of complications and adverse outcomes like miscarriages and stillbirth.9
    Children exposed to nicotine in the womb are more predisposed to health problems throughout their lifetimes. These health problems affect their endocrine, reproductive, neurologic, respiratory, and cardiovascular systems.9
    Nicotine use can cause cardiac arrhythmia—a cardiovascular condition characterized by an irregular heartbeat.10"

[klik99]

We're talking about nicotine, not smoking. There is no evidence that nicotine is carcinogenic.

https://www.cancerresearchuk.org/about-cancer/causes-of-canc...

> Nicotine is the chemical that makes cigarettes addictive. But it is not responsible for the harmful effects of smoking, and nicotine does not cause cancer. People have safely used nicotine replacement therapy (NRT) to stop smoking for many years. Nicotine replacement therapy is prescribed by doctors or is available from pharmacies.

The risks for hypertension, etc is true for nicotine, because it's a stimulant, so same risks exist for coffee. There is very little conclusive evidence that nicotine (not talking about smoking or vaping) has any health effects that aren't also caused by coffee/stimulants.

The best thing you can say about vaping is that it's very understudied and long term effects are unknown, and likely has some long term effects that are bad for you.

Smokeless nicotine (swedish snus-variety) is considered very safe.

The problem is smoking and nicotine have been so intertwined for so long that when they say "Nicotine causes x" most of the time what they mean is "Smoking causes x" and maybe also "Vaping could potentially cause x"

[DrThunder]

False. I provided you the evidence. Here's more, keep lying if it makes you feel better.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553893/ "In several in vitro experiments, it has been found that nicotine in concentrations as low as 1 μM decreased the anti-proliferative and pro-apoptotic effects exerted by chemotherapeutics on several different malignant cell lines"

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4363846/ "There is decreased immune response and it also poses ill impacts on the reproductive health. It affects the cell proliferation, oxidative stress, apoptosis, DNA mutation by various mechanisms which leads to cancer."

Are you a big vaper or something and this is upsetting to you or something? I can't see any other reason for you to react with outright lies.

[klik99]

Your previous comment didn't include any evidence, but these are pretty interesting. The second one is more damning, but again the majority of studies were on smokers. I'll update my statement and say there is little evidence that nicotine by itself is carcinogenic. As the second article says "The IARC monograph has not included nicotine as a carcinogen." so it's still not conclusive. The strongest thing I see in the second article is that nicotine can help promote existing tumors, that's concerning.

But the way science works is by having lots of viewpoints and research - there are also plenty of papers on how nicotine is not carcinogenic.

"Smokers commonly misperceive that nicotine is a major carcinogen" - https://thorax.bmj.com/content/66/4/353#ref-2

"The literature to February 2019 suggests that there is no increased cardiovascular risk of nicotine exposure in consumers who have no underlying cardiovascular pathology. There is scientific consensus that nicotine is not a direct or complete carcinogen, however, it remains to be established whether it plays some role in human cancer propagation and metastasis. " - https://f1000research.com/articles/8-1586 (This is what I saw in the second article - looks like there is a chance that nicotine can promote existing cancer)

"The devastating link between tobacco products and human cancers results from a powerful alliance of two factors — nicotine and carcinogens. Without either one of these, tobacco would be just another commodity, instead of being the single greatest cause of death due to preventable cancer. Nicotine is addictive and toxic, but it is not carcinogenic. This addiction, however, causes people to use tobacco products continually, and these products contain many carcinogens." - https://www.nature.com/articles/nrc1190

I am not a vaper, I do use patches and gum. I believe that damning nicotine prevents the development of replacements for smoking which is incredibly dangerous. I don't vape because research on that is in really early stages, and there's a good chance there might be something bad in the long term, though there is no strong evidence that it is worst than other NRT, except that levels of NNAL are higher (see the first paper you posted).

Edit To clarify that you didn't provide evidence in your first post - you linked to https://www.verywellhealth.com/what-is-nicotine-5075412 which has citations, but the comments about nicotine being carcinogenic linked to studies that studied smoking, not NRT or non-smoke based nicotine.

[Veen]

These are all health risks associated with smoking, not with nicotine itself. If you click through to the pages those risks link to, you'll see they are talking about smoking, not nicotine. There are some risks from nicotine (high blood pressure and faster heart rate), but it does not cause emphysema or cancer.

[fatfingerd]

Do we really know what portion of this isn't just correlation between nicotine and the fact that it has to be administered which usually involves smoke, fiberglass irritation, etc?

I think the main problem with nicotine is its addictiveness and the fact that that will lead you to accept risks in administration via cigarettes, toxic fluid vapors, chew with fiberglass, etc.