Quitting smoking by sheer will-power is one of the best things that smokers can do for themselves. But for those who find it difficult, there is a substitute in the form of electronic cigarette, which is gradually picking up in the world.

While the concept of e cigaret has been around for four decades, they made their commercial debut only in 2004. And research says about 55% of people quit smoking after using the electronic cigarette as a substitute for real ones.

The electronic cigarettes come in a variety of shapes. Some look like cigarettes, pipes, or cigars, while others are disguised as pens or other more socially acceptable items. Whatever their shape, they all are built around a battery-operated heating element, a replaceable cartridge that contains nicotine and other chemicals, and an atomizer that converts the chemicals into inhale vapor.

However, a study published in the American Journal of Preventive Medicine concluded that electronic cigarettes may help smokers quit the hobby. Whether they are a safe way to quit is another question and preliminary studies from the Food and Drug Administration (FDA) New Zealand and Greece raise some concerns.

And there is a word of caution. There are three reasons to worry about colored e cigarettes. 

First, the dose of nicotine delivered with each puff may vary substantially. An FDA analysis recorded nicotine doses between 26.8 and 43.2 micrograms per puff. It also detected nicotine in products labeled as nicotine free.

Second,ecig deliver an array of other chemicals, including diethylene glycol (a highly toxic substance), various nitrosamines (powerful carcinogens found in tobacco), and at least four other chemicals suspected of being harmful to humans. To be sure, the dose of these compounds is generally smaller than found in "real" cigarette smoke. But it is not zero.

Third, by simulating the cigarette experience, electronic cigarettes might reactivate the habit in ex-smokers.