E-cigarettes: Where do we stand?

(CNN)E-cigarettes are increasingly being used as a nicotine alternative as smokers seek ways to kick their habit. They work by heating a pure liquid called e-juice — composed of flavorings, propylene glycol, glycerin and often nicotine — until it vaporizes. The resulting vapor is much less offensive to many, both smokers and non-smokers.

But their use has been surrounded by debate, focusing on the lack of evidence regarding the harms associated with their long-term use, as well as their potential to act as a gateway into smoking among teens.
The latest salvo: A study published Monday in the journal Pediatrics found five cancer-causing toxins in the urine of 16-year-olds who inhaled e-cigarette vapor, and a second study found, yet again, that e-cigarettes encourage teens to begin smoking traditional cigarettes.
Last week, a study of nearly 70,000 people found that daily e-cigarette use can double the risk for heart attack. If the user continues to smoke regular cigarettes each day along with e-cigarettes, the combined risk goes up five times.
“E-cigarettes are widely promoted as a smoking cessation aid, but for most people, they actually make it harder to quit smoking, so most people end up as so-called ‘dual users’ who keep smoking while using e-cigarettes,” said Stanton Glantz, lead author of the latter study, in a statement.
Science and public policy have bounced back and forth for over a decade, as different studies produce different — and sometimes contradictory — results. Let’s take a look at the debate over the years:

2003 headline: Invention of e-cigarettes

The inventor of the electronic cigarette, Hon Lik, smoking his invention in Beiijng on May 25, 2009.

Three pack-a-day smoker Hon Lik, a 52-year-old Beijing pharmacist, created the first successful electronic cigarette after his father, another heavy smoker, died of lung cancer. By 2007, e-cigarettes were marketed in Europe and the United States by manufacturer Ruyan as a way to safely stop smoking tobacco.
Hon was not the first person on record to have the idea for an electronic non-tobacco option. Herbert A. Gilbert filed for a patent in 1963, in an era when tobacco smoking was widely accepted and the health risks were less apparent.