PhotoMuch of the controversy over electronic cigarettes has centered around their nicotine content, but a study by Harvard researchers has found a chemical linked to severe respiratory disease in more than 75% of flavored e-cigarettes.

Diacetyl is a flavoring chemical that can cause bronchiolitis obliterans, commonly known as "popcorn lung" because it first appeared in workers who inhaled artificial butter flavor in microwave popcorn plants.

The Harvard T.H. Chan School of Public Health researchers found diacetyl and two other potentially harmful compounds in many flavored e-cigs, including those targeted to young people with flavors such as cotton candy, “Fruit Squirts,” and cupcake.

“Recognition of the hazards associated with inhaling flavoring chemicals started with ‘popcorn lung’ over a decade ago. However, diacetyl and other related flavoring chemicals are used in many other flavors beyond butter-flavored popcorn, including fruit flavors, alcohol flavors, and, we learned in our study, candy-flavored e-cigarettes,” said lead author Joseph Allen, assistant professor of exposure assessment sciences.

Dangers are well-known

The dangers of inhaling diacetyl are well-known and the Occupational Safety and Health Administration (OSHA) warns employers about the risks posed to workers exposed to the chemical.

The study, published today in Environmental Health Perspectives, notes that there are currently more than 7,000 varieties of flavored e-cigarettes and e-juice (nicotine-containing liquid that is used in refillable devices) on the market.

E-cigarettes are not currently regulated, although the U.S. Food and Drug Administration (FDA) has issued a proposed rule to include e-cigarettes under its authority to regulate certain tobacco and nicotine-containing products.

In the study, Allen and colleagues tested 51 types of flavored e-cigarettes and liquids for the presence of diacetyl, acetoin, and 2,3-pentanedione, two related flavoring compounds that the Flavor and Extract Manufacturers Association lists as “high priority,” meaning they may pose a respiratory hazard in the workplace.

At least one of the three chemicals was detected in 47 of the 51 flavors tested. Diacetyl was detected above the laboratory limit of detection in 39 of the flavors tested. Acetoin and 2,3-pentanedione were detected in 46 and 23 and of the flavors, respectively.

“Since most of the health concerns about e-cigarettes have focused on nicotine, there is still much we do not know about e-cigarettes. In addition to containing varying levels of the addictive substance nicotine, they also contain other cancer-causing chemicals, such as formaldehyde, and as our study shows, flavoring chemicals that can cause lung damage,” said study co-author David Christiani, Elkan Blout Professor of Environmental Genetics.

Share your Comments