Evaluation of Electronic Cigarette Liquids and Aerosol for the Presence of Selected Inhalation Toxins

INTRODUCTION:

The purpose of this study was to evaluate sweet-flavoured electronic cigarette (EC) liquids for the presence of diacetyl (DA) and acetyl propionyl (AP), which are chemicals approved for food use but are associated with respiratory disease when inhaled.

METHODS:

In total, 159 samples were purchased from 36 manufacturers and retailers from 7 countries. Additionally, three liquids were prepared by dissolving a concentrated flavour sample of known DA and AP levels at 5%, 10% and 20% concentration in a mixture of propylene glycol and glycerol. Aerosol produced by an EC was analyzed to determine the concentration of DA and AP.

RESULTS:

DA and AP were found in 74.2% of the samples, with more samples containing DA. Similar concentrations were found in liquid and aerosol for both chemicals. The median daily exposure levels were 56μg/day (IQR: 26-278μg/day) for DA and 91μg/day (IQR: 20-432μg/day) for AP. They were slightly lower than the strict NIOSH-defined safety limits for occupational exposure and 100 and 10 times lower compared to smoking respectively; however, 47.3% of DA and 41.5% of AP-containing samples exposed consumers to levels higher than the safety limits.

CONCLUSIONS:

DA and AP were found in a large proportion of sweet-flavoured EC liquids, with many of them exposing users to higher than safety levels. Their presence in EC liquids represents an avoidable risk. Proper measures should be taken by EC liquid manufacturers and flavouring suppliers to eliminate these hazards from the products, without necessarily limiting the availability of sweet flavours.