I agree that vaping isn't 100% safe, nothing is, but I'm not sure I'd compare it to rock climbing with great equipment.Agreed.
I also think we (collectively) have to start thinking about e-Cigarette use more as a Wide Category.
Just like being Top Roped on a Hand over Hand jumble is Different from Leading a 5-10+ Open Vert, e-Cigarette use comes in Every Flavor of the Rainbow.
Can't state any Studies or provide any Links. But there has to be a Different Degree of Potential Harm in vaping 1.5ml/Day of Unflavored @ 300F than there is at vaping 20ml/Day of Heavily Flavored/Sweetened e-liquid @ 480F+.
For me, it's analogous to drinking municipal tap water. It's relatively safe. It's always good to know about the sources to make sure there are no major issues with contaminants, and it may be a good idea to put a filter on your water main. Now, TC might be like taking the extra precaution of also running your drinking water through filter pitcher or something like that.
Now, if you take that water and add sugary drink mixes to it, it's not as good for you, but it's still water. Of course you could always slip and drown in your bathtub, or break a glass and cut your hand(exploding battery), but that's not an inherent issue with the water.
Actually, depending on where you live, vaping might be safer than the tap water.