New RCSI research has uncovered the potentially harmful substances that are produced when e-liquids in vaping devices are heated for inhalation.

The study, published in Scientific Reports, highlights the urgent need for public health policies concerning flavoured vapes. 

The research team in RCSI’s Department of Chemistry used artificial intelligence (AI) to simulate the effects of heating e-liquid flavour chemicals found in nicotine vapes. They included all 180 known e-liquid flavour chemicals, predicting the new compounds formed when these substances are heated within a vaping device immediately prior to inhalation. 

The analysis revealed the formation of many hazardous chemicals including 127 that are classified as ‘acute toxic’, 153 as ‘health hazards’ and 225 as ‘irritants’. Notably, these included a group of chemicals called volatile carbonyls (VCs), which are known to pose health risks. Sources for VCs were predicted to be the most popular fruit, candy and dessert-flavoured products. 

Lead author Professor Donal O’Shea, Professor of Chemistry and Head of Department, said the findings are very concerning: “We wanted to understand, before it’s too late, the likely impact flavoured vapes are having on the health of the growing number of vapers. Our findings indicate a significantly different profile of chemical hazards compared to what we are familiar with from traditional tobacco smoking.

“It is plausible that we are on the cusp of a new wave of chronic diseases that will emerge 15 to 20 years from now due to these exposures. We hope this research will help people make more informed choices and contribute to the conversation on the potential long-term health risks and the regulation of vaping, which this research suggests should be comprehensive.” 

The study also highlighted the complexities introduced by the huge array of flavours available in vaping products, which include 180 different chemicals blended in various amounts. This cocktail of chemicals, primarily derived from the food industry where they have a good safety record for specific uses, were never intended to be heated to high temperatures for inhalation. 

As vaping devices vary widely and are often user-customised, the temperature control and resulting chemical reactions can differ, increasing the unpredictability of potential health risks. This variability requires further research using the AI framework established in this study, which could also lead to the development of risk reports for individual flavours, providing an informative public health policy resource. 

Considering the popularity of flavoured vapes among non-smoking teenagers and young adults, understanding the long-term effects of these products on public health, morbidity and mortality is crucial. This study demonstrates that without comprehensive regulation, as we try to treat the nicotine addictions of older tobacco smokers, there is a substantial risk of transferring new health issues to younger generations. 

The research was carried out in conjunction with IBM Research – Tokyo and was supported by Science Foundation Ireland (SFI) and the Irish Research Council through the SFI-IRC Pathway Programme for Dr Dan Wu. Details are published in the paper ‘Forecasting vaping health risks through neural network model prediction of flavour pyrolysis reactions’ in Scientific Reports.