you know, i always find it strange vapers use this argument... it's scientific, sure, but it doesn't work to exclude vaping as a potential health risk. it actually defers even considering it. like cig companies do when they ask a cancer-ridden plaintiff, do you have lead paint or asbestos in your house... unlike a scientist, legislator or manufacturer, we should actually be vested in knowing if vaping can cause problems, not maintaining our ignorance whether it might.
(i'm sure you and most others that have used this argument actually care and would be very sensible in receiving negative results from a legitimate study_ just saying the argument goes against our interest and should only be used to counter unjustified legislation or uneducated, pseudo-scientific blabber... not a fellow vaper who is trying to rule out vaping as a cause to whatever problem they have [giving the OP the benefit of the doubt, that they are not a propagandist/antivape ~campaigner])