I hadn't heard about this encouraging study. I copied and pasted the quote below from the above wikipedia page:
Boston University School of Public Health study
A study done by researchers at the Boston University School of Public Health in 2010 concluded that electronic cigarettes were safer than real cigarettes and may aid in breaking the habit of smoking. The researchers said that while further studies on electronic cigarettes are needed, "[f]ew, if any, chemicals at levels detected in electronic cigarettes raise serious health concerns." Electronic cigarettes were found to be "much safer" than traditional
tobacco ones, and had a level of toxicity similar to existing nicotine replacements.[19][20][21]
In the report, the level of carcinogens in electronic cigarettes was found to be up to 1,000 times lower than regular cigarettes. It also said early evidence shows that electronic cigarettes may help people to stop smoking by simulating a
tobacco cigarette.[19][20]