Tobacco Researcher: Most E-Liquid Flavor Compounds Far Below Toxic Levels

Recently, a study raised concerns about the toxicity of e-liquids by reporting the presence of 14 flavoring chemicals with toxic classifications, identifying several chemical compounds in vape juice that may irritate the respiratory tract. The researchers noted that the liquids analyzed did not comply with current EU e-cigarette regulations (the Tobacco Products Directive).

However, responding to the study, well-known tobacco researcher Dr. Konstantinos Farsalinos pointed out that although the flavoring chemicals were identified and quantified, the study did not calculate the potential toxicity of those chemicals at their observed concentrations.

To address this, Farsalinos repeated the research and examined the toxicity classifications of the different chemicals at their maximum reported concentrations, as in the initial study. The aim was to determine whether warning labels would be legally required on the products under TPD rules based on the flavoring levels.

Farsalinos and his team compared the concentration of each flavor compound with the lowest concentration at which it would be classified as toxic. In addition, the researchers analyzed the toxicity classification of a theoretical e-liquid containing all of the flavoring chemicals.

“At least one toxicological classification was assigned to all flavoring chemicals, with the most common classifications related to skin, oral, eye, and respiratory toxicity,” the researchers reported. One chemical, methylcyclopentenolone, had a maximum concentration 150.7% higher than the concentration at which it would be classified as toxic.

“The rest had reported maximum concentrations 71.6%-99.9% below toxic levels. The liquid containing the maximum concentrations of all flavor compounds was classified as a Category 1 toxic substance solely because of the presence of methylcyclopentenolone; the flavoring concentrations in a liquid without methylcyclopentenolone were 66.7%-99.9% lower than those required for classification as toxic substances.”

Flavor compound levels are far below toxic thresholds

Farsalinos and his team concluded that the vast majority of flavor compounds reported in the original study were present in e-cigarette liquid at levels far below the thresholds considered toxic. They added: “Because not all liquids are equal, regulatory monitoring of liquid ingredients is necessary.”