The main thing to remember is that electronic cigarettes emit a vapor, not smoke. When you burn a roast in the oven, that's smoke. When you boil water on the stove, that's vapor. Big difference.
Obviously, what's IN the vapor is the concern here, so here's a list of ingredients: propylene glycol, vegetable glycerine, distilled water, food grade flavoring, citric acid, nicotine (optional). The ingredients vary some by manufacturer, but that's what's in the solution in my electronic cigarette.
I don't know if electronic cigarettes are 100% safe, but I do know they're a LOT safer than
tobacco cigarettes. And as former smoker, I certainly feel better inhaling vapor than I did inhaling toxic smoke. No one around me is bothered by it in the slightest either. In fact, they actually like the smell of it.
"we do not know yet the health effects of inhaling pure nicotine"
Really? The Nicotrol Inhaler, which delivers pure nicotine by inhalation, is FDA approved.
"some of the most popular e-cigarette brands contain carcinogens – they could still cause cancer."
While technically true, it's a bit misleading to say electronic cigarettes contain carcinogens. The carcinogens found in e-cigarettes are also present in pharmaceutical nicotine products (gum, lozenges, inhaler, etc) because nicotine is derived from
tobacco. The risk is insignificant at those levels.
"The FDA has also detected a toxic chemical found in antifreeze in some leading brands."
Diethylene Glycol was a trace contaminant (not an ingredient) found in one of the cartridges that the FDA tested. I think people get confused about this issue because the main ingredient in the vapor solution in electronic cigarettes is PROPYLENE glycol, which is used in some antifreezes (that are made to be less toxic than regular antifreeze). Propylene glycol, however, is not toxic. It is considered safe for human consumption by the FDA. It's used in food products, hygiene and cosmetic products, medicines and... well, just start looking at product labels. People use it and ingest it daily.