How safe are electronic cigarettes?

Why ask?: The non-nicotine e-cigarettes use water vapor to simulate smoking, but why "simulate" at all? Try sugarless gum or sugarless stick suckers if you must have the oral fixation. The e-cigarettes that provide nicotine at least do not have the tar and carbon monoxide, but the nicotine is still a potent vasoconstrictor and metabolic drug. Just say no to cigarettes and tobacco of any kind! please!

E- cigarettes: E- cigarettes may contain nicotine, volatile organic compounds, heavy metals (like lead, tin & nickel), ultrafine particles (which may be drawn deep into lungs, diacetyl and Nicotine which is addictive. REF: https://e-cigarettes.surgeongeneral.gov/ Electronic cigarettes may harm health - especially in young people.