An electronic cigarette or “e-cigarette” is a device that heats a liquid and causes a vapor that the user inhales. Unlike a traditional paper cigarette, there is no combustion with an electronic cigarette.
An electronic cigarette is composed of three elements:

• a battery 
• a reservoir containing a liquid known as “e-liquid” 
• an electrical resistor that heats the liquid and turns it into a vapor.

Since the launch of the electronic cigarette in 2003, there have been different generations of electronic cigarettes:

• 1st generation, also known as “cigalikes”, a simple and cheaper model; some models are disposable, others rechargeable 
• 2nd generation, with a rechargeable battery that is larger and more powerful than the 1st generation “cigalikes” 
• 3rd generation, also known as “personalized vaporizers”, with a battery that is more powerful than 2nd generation electronic cigarettes and more options (change battery voltage to generate more vapor, customize compartments, etc.).

The electronic cigarette vaporizes a liquid whose base is generally composed of solvents:

• propylene glycol
• and/or glycerol.

Propylene glycol and glycerol are used in pharmaceutical, cosmetic and food preparations. Propylene glycol is also used to generate artificial fog in theaters. Inhaling it may cause respiratory irritation.
 Other ingredients can be added to this basic “e-liquid”:

• flavors 
• nicotine.

DID YOU KNOW? Substances introduced voluntarily into e-liquids (solvents, flavorings and other additives) must be distinguished from substances generated during the vaporization process (aldehydes, metals, etc.)

To date, we do not have enough background or scientific studies to assess the long-term risks or lack of risk of electronic cigarettes. It can be assumed that the electronic cigarette is a less dangerous alternative than smoking, but vaping will always be less healthy than not vaping anything at all.
Electronic cigarettes pose several health and social risks:

• risk in children of severe and fatal poisoning with nicotine-containing “e-liquids” 
• risk of inhaling vapor containing chemical impurities (aldehydes), harmful substances (nitrosamines) or substances whose effects are not yet known (inhaled flavors) 
• risk of normalizing the act of vaping, initiating non-smokers, creating and maintaining nicotine addiction
• explosion risk depending on the quality of electronic cigarette models.

DID YOU KNOW? The health risks of the electronic cigarette depend greatly on how it is used: the number of inhalations per day, the duration of inhalation, the heating temperature, etc. Depending on the use of the electronic cigarette, inhalation of substances found in vapors can irritate the respiratory tract and cause palpitations.

The flavors added to the “e-liquid” are the same as those used as food additives. However, the health effects of such flavorings are not known when they are heated and inhaled instead of ingested.

DID YOU KNOW? Some flavors may be more harmful to health than others. Flavors of caramel, butter or biscuits sometimes contain diacetyl and acetylpropionyl, substances known to be harmful.

Aldehydes are harmful substances resulting from the thermal decomposition of the solvents (propylene glycol and glycerol) that form the basis of the e-liquid. Among aldehydes, formaldehyde is a substance known to be carcinogenic. 
The formation of aldehydes occurs mainly when the resistor of the electronic cigarette heats up when there is not enough or no more “e-liquid”. This inhaled vapor, also called dry puff, has a very specific unpleasant taste. However, the quantities of aldehydes found in electronic cigarette vapor are much lower than those found in cigarettes.

If nicotine is not the most dangerous part of a traditional paper cigarette, its consumption through electronic cigarettes raises questions. 
What are the dangers of “pure” nicotine consumed outside paper cigarettes? What are the long-term risks of nicotine addiction? What are the dangers for those around you who inhale vapor containing nicotine (passive vaping)? All of these issues are yet to be scientifically researched.
Attention! At high doses, nicotine is a poison that can be toxic and lethal.

Nitrosamines are carcinogenic substances that are 400 times more present in cigarette smoke than in electronic cigarette vapor. However, its low concentration in electronic cigarettes may increase the risk of respiratory tumors.

Electronic cigarettes should only be used as a means for smokers to stop smoking and not as an end in themselves or as a new habit to be adopted in the long term.