Since there are limitless facts and truths, you have to start by knocking down the common misconceptions and complete misunderstandings. What a sales-man says, and what is published as advertisement, are two complete separate things.
These are harmless. (Lie. Nothing is harmless.)
These are less harmful than cigarettes. (Possible, but there is missing information.)
These are healthy. (Lie. There is no study that indicates that the health was improved by every individual.)
These are more healthy than cigarettes. (Possibly, but there is missing information.)
The full disclosure of the reports, along with the direct facts in the statement, are "The truth/facts", as far as the law and we are concerned, until proven otherwise.
Once the manufactures release the actual sold contents, then the item can safely be debated. Until then, we have to assume the contents are being hidden, because they contain chemicals which may or have been proven to harm us in some way.
Ryuan uses synthetic nicotine, not natural nicotine. Some places use natural nicotine, which rightly also contains many or some of the chemicals from the tobacco it was extracted from. Some manufactures are just selling tobacco water.
Additives on some sites are being disclosed. However, they sell "Flavors" which they do not disclose the ingredients for. Quantity in the ingredients is also important, as that helps determine the consumption level.
Most are using standard food flavoring, which are acceptable for normal consumption. However, inhalation has not thoroughly been studied. But in all fairness, it sort-of has, as the factory workers who manufacture the stuff have been manufacturing for years, and breathing in the vapors for 8-hour days, 365-days a year. (Weekends and holidays permitted)
The nicotine vapor has been studied over and over and over again. Nicotine ingestion is only done one way... liquid consumption. (Inhaled when you smoke or vaporize it, and swallowed or absorbed when not inhaled.)
It is safe to assume that if one known element which is the "Leading cause of cancer in cigarettes", is not present in another form, that the item is safer. That is safe logical deduction. Tar and carbon monoxide from combustion, are the two largest carcinogens in an ignited tobacco product.
If those are not present, those can not contribute. The two largest elements within liquid-nicotine, are known to be safer than the two largest elements within an ignited tobacco product. So logical deduction would safely allow us to assume that it is not as unhealthy as an ignited tobacco product.
Those are the same "Assumptions", that medical studies make, when 10000 rats live, and only 10 rats die. Testing is still assumptions, and playing the odds. It is not "Fact" or "Truth", just better potential odds. (Potential, because ten years from now, they may determine rats results don't correlate with human results.)
What if aspirin long term effects caused your head to explode! But it took 100 years to happen. We would have to wait 100 years for that study, and for what... the 2% of people who live past 99, and of that, the 2% who took the aspirin long enough to have their heads explode... could be safe...
You can study it for 100 years, and that information will be useless on the next genetic generation of users.
What you do, is report it, when it happens, to be looked at and studied. If it is actually a problem, and not an isolated incident, then you take action. Yes it is too late. It will always be too late. Knowing about it does not stop it from happening to you. It could be 1 in a billion, and you could be the one it happens to.
It will become more clear soon, because of these actions. This is just a transition that would not have happened on its own. Sadly, and rightfully, it needed intervention. All we can do is hope that it does not end-up leaving a sour taste in our mouths.