Abstract:
Electronic cigarettes (e-cigarettes) have rapidly gained popularity recently, especially in
younger adults. Evidence to date suggests that e-cigarettes are safer than conventional
cigarettes but are not harmless. E-cigarettes use e-liquids to aerosolise the general ingredients
including propylene glycol, vegetable glycerine, nicotine and flavourings. New toxic
compounds can be formed after aerosolising the e-liquid. This project evaluated the chemical
composition, including heavy metal analysis, in NZ-made e-liquids with various formulations
and resulting aerosol condensates under different vaping conditions. Vaping conditions
included ISO 20769:2018 standard conditions, lower and higher power settings of 10W and
80W, and a longer puff duration of 5 seconds.
The chemical analysis of nicotine, flavourings, and degradation products was performed using
Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry (HS-SPME
GC-MS). Results demonstrated 142 flavourings, nicotine and two nicotine-related degradation
products called nicotyrine and myosmine. Trace elements of nicotine appeared in e-liquids that
claimed to be nicotine-free, and trace elements of flavourings were present in products labelled
as flavourless. High temperatures in e-cigarettes have been found to degrade components into
toxic chemicals. One of the flavouring-related degradations, formaldehyde in condensates was
not detected via GC-MS but was detected through preliminary High-Performance Liquid
Chromatography.
The heavy metal analysis of twenty-two elements was performed using Inductively Coupled
Plasma Mass Spectrometry. The e-liquids contained eighteen metals at dangerous levels that
exceeded the occupational health standard limitation. Metal present in highest concentration
was silicon which made up 98.9% of total metal content. After aerosolisation, increases in
several metals were found such as Fe, Zn and Cr at the highest concentrations.
Increased device power setting and puff duration led to elevated coil temperatures and oxygen
supply, resulting in more toxicants with higher concentrations in e-liquid emissions, including
nicotine, nicotyrine, myosmine, and heavy metals. Assessment of the literature to link
chemicals found with negative health implications was conducted. Many of the chemicals
detected in this study have been linked with adverse health consequences, especially to lung
function and the respiratory system as a whole.
This body of work provided the first characterisation of the chemical composition of NZ-made
e-liquids and a foundation for regulating these products.