Two sides to the argument, but the anti side is still using 4 year old data. ......

Tests have shown that electronic cigarettes have plenty of impurities, she said. In 2009, the FDA tested two popular brands of e-cigarettes and flavor cartridges. The study found low levels of carcinogens in both brands, and some of the cartridges labeled nicotine-free actually contained small amounts of nicotine. And a small amount of diethylene glycol was detected in one product. The compound, used in antifreeze, is toxic to humans.

Smokers turn to 'vaping' to give up the habit - Houston Chronicle