I guess using your reasoning you could say 'nothing is safe' eating too much salt can kill you, drinking too much water can kill you, dairy products, eggs, and leafy greens might be contaminated with salmonella and kill you, a caffeine overdose can kill you..
I know what I am introducing into my system when I vape, and none of it in reasonable amounts is known to have ANY long term effect:
nicotine - in small amounts not toxic and may have some positive effects, improves short term memory, reduces incidence of ulcerative colitis, decreases symptoms of adhd
PG non-toxic, used in toothpaste, cake mix, nebulizers and asthma inhalers
VG non-toxic used in many foods, cosmetic products nebulizers and asthma inhalers
Food Grade Flavoring safe with some precautions- avoid food flavorings with diacetyl, acetaldehyde and capsaicin.
Now, please tell me what is it about vaping that you think might cause "long term effects"