[samatman]

Yes, this is an important comparison when there is adequate data.

Which, we're not really starting from the null hypothesis at this point, but let's pretend that we are.

Starting from no data, saying that there's no evidence that vaping is less harmful than cigarettes is no different from saying there's no evidence that vaping is less harmful than guavas.

There's no evidence. That's where the sentence needs to stop. Then you get evidence, and we can have an informed conversation.

[ineedasername]

I think where we disagree is on "no evidence". There is not definitive, comprehensive evidence, but there is some evidence. Nicotine, for example, is fairly well understood and so the knowledge base for that is shared between traditional cigarettes and vaping. We also know from chemical analysis that something like Juul has fewer & lower levels of known carcinogens. We don't know long term effects of inhaling novel chemicals found in vaping but not cigarettes, and that is a major gap.

However, in the face of having to form public health policy decisions in the time between right now and a decade+ down the road where real, long-term studies can be completed, we can only use and compare that available data. Though we should hew very close to specific facts and avoid words open to very wide interpretation like "safer". (it may be safer along a single vector, carcinogens, but much worse in others, so it's a misleading term) We would be more wise to stick to specific known evidence like:

--Nicotine levels are similar, so there is little or no difference in health issues related to nicotine ingestion, except in so far as evidence shows nicotine salts used in vaping may hit your system faster.

--There are fewer known carcinogens or lower levels of them in vaping, but the effects of novel chemicals are not known. Short term health benefits in switching to vaping have been observed but longer terms outcomes are completely unknown, and could be worse.

--Use Risk, as apposed to a more ambiguous "safety", and say that vaping is not a risk-free activity from a health perspective.

The above could probably still be better stated, but I think the point is clear enough. This is no different than any other scientific issue or area of research. You use available data to convey the current state of knowledge, possible implications, further areas of study, etc. And as more data arrives, you expand and revise. But we're not starting from zero data.

A primary issue in this topic is that it is front & center in the media. Media in general is not good at conveying technical nuances, and the well-funded marketing arms of tobacco (and now vaping) companies have every reason to help the media make incorrect leaps of logic and over generalizations, e.g, fewer carcinogens == safer.

Another consideration is individual context: I'm trying to get my 67 year old father to switch from smoking to vaping because available evidence shows he will very likely be able to breath more easily, reduce his risk for heart disease, and so on. But he's 67: Long term risk from unknown vaping effects are probably a non issue for him, while he's about 4 years away from COPD. And there's zero chance of getting him to quit while I'd peg my chances around 1 in 10 of getting him to vape instead. If it were a friend my own age, I would have a different message, such as "You may very well be trading some short-term health for long-term issues that are as bad, or worse. Or maybe not, but we don't know, so quitting is the proper response, not switching to vaping"

[samatman]

> I think where we disagree is on "no evidence". There is not definitive, comprehensive evidence, but there is some evidence.

We don't disagree on this, as I indicated, we're not starting from a null hypothesis here. It's a useful abstraction for the sake of argument.

All available evidence suggests that vaping is dramatically less harmful than cigarettes. There is a large enough population, who have been vaping long enough, that we should have some evidence to the contrary by now, if any was to be forthcoming.

Cigarette smoke, in addition to dozens of known carcinogens, contains small particle and carbon monoxide. Both of which are known to be terrible for your health, both of which are completely absent in vaping.

If I were trying to convince a young person not to vape, I'd stress that nicotine addition is a pointless and expensive mental slavery that is best avoided. Unless I knew they had ADHD or schizophrenia, in which case I'd leave them alone, since other people's medication is none of my business.

Stressing unknown harms that haven't been observed and probably won't be is a bad argument. They would be right to ignore it.

[ineedasername]

>>Stressing unknown harms

We have to measure and make decisions about unknown harms every day. We're not always good at it, but it's unavoidable. With respect to vaping, we know of very little in the way of foreign chemicals that can be safely inhaled. I think it's fair to say that available medical knowledge about inhaling chemicals points to a non-negligible chance that it might be bad for you. You seem to be saying we should mostly avoid reasoning about such uncertain risks. I'm saying it's not unreasonable to tell people, "we know inhaling many type of chemicals is harmful to your health, so there is potential for harm here as well. We'll know more in about a decade, and be fairly certain in 30 or 40 years."

Scientific rigor does not preclude reasoning about these risks before those 10 to 40 years are up.

[samatman]

If we don't inhale chemicals we die in a matter of minutes.