E-liquid emissions


An EU e-liquid manufacturer.


The Tobacco Products Directive 2014/14/EU (TPD) requires the emissions from electronic nicotine delivery systems (ENDS) to be analytically identified and quantified. Information regarding key carbonyl compounds, notably formaldehyde, acetaldehyde, acrolein, diacetyl (2,3-butanedione) and acetyl propionyl (2,3-pentanedione), “should always be submitted” as part of a TPD notification according to MHRA guidance. These carbonyl compounds are generated during the heating of e-liquid as thermal degradation products, and/or are associated with concerning toxicological properties. The detection and quantification of other aldehydes including crotonaldehyde, propanal and butanal is often also recommended.

Project goals

These key carbonyls were detected in emissions from an e-liquid product using high performance liquid chromatography – mass spectrometry (HPLC-MS) using techniques adapted from CORESTA Recommended Method No. 74.

Bibra was provided with the analytical results of the emissions analysis and asked to conduct a preliminary assessment of the health risks posed by the detected aldehydes and α-diketones in marketed e-liquids.


Searches for key toxicity data were carried out using bibra’s in-house database, TRACE. The key data were summarised by bibra toxicologists, with a focus on available health criteria values (HCVs) derived by Expert Groups (particularly inhalation HCVs, where available). Key local and systemic (cancer and non-cancer) points of departure (PoDs) for risk assessment were identified and described. These were compared to estimated consumer exposures, as calculated by bibra. A consideration of the possible additive effect of these carbonyls was included in the risk assessment report, where appropriate as some of these compounds are expected to have similar modes-of-action (MoA).

Project outcome

Bibra supplied the client with a consumer health risk assessment of the key emission compounds.

Project Team

Charlie Johnson
Richard Young
Pete Watts
Beth O’Connell


Electronic Cigarettes

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