E-cigarette users have over 7,000 e-juice flavors to choose from when smoking. These e-juices are liquids containing nicotine that are vaporized through the device. As the popularity for these items increases, more and more flavors are being produced. However, there is not a large amount of data released on the health effects of these products.

A study published in Environmental Health Perspectives finds that Diacetyl is found in 75 percent of e-juices. Diacetyl is a chemical used in flavoring that is often linked to severe respiratory diseases. It was also found that there are two other possibly dangerous chemicals in the liquids, Acetoin and 2,3-pentanedione.

The researchers on the study from the Harvard T.H. Chan School of Public Health tested 51 e-cigarette liquid products. They placed each e-cigarette into a chamber that drew air, which was then analyzed. Diacetyl was found in 39 of the flavors, Acetoin in 46 of the flavors and 2,3-pentanedione in 23 of the flavors.

E-cigarette products are currently not regulated by the U.S. Food and Drug Administration (FDA).