The flavours used in some e-cigarettes may cause allergy in airways, worsening the severity of diseases such as asthma, according to a study.
In a first, researchers including those from the University of Technology Sydney (UTS) in Australia, used the model of asthma to investigate the effect of popular e-cigarette flavours both with and without nicotine.
The study, published in the journal Scientific Reports, noted that the use of e-cigarettes has dramatically increased in the last few years with an estimated nine per cent of 18-24 year olds in the US currently using the devices. The results of the study indicate that some flavoured e-cigarettes -- even when they do not contain nicotine -- may alter the function of respiratory pathways affected by allergic disease.
"This is especially important for those with respiratory disease, who are vulnerable to the effects of smoking," said David Chapman, UTS researcher and lead author of the study. He added that the majority of e-cigarette smokers used flavoured liquids while there was evidence that the flavour additives can be toxic when inhaled.
"The exact effects on features of asthma were dependent upon the specific flavour, suggesting not all flavoured e-cigarettes will have the same consequences on lung health," Chapman said. Black Licorice, a flavour studied by the researchers, exaggerated airway inflammation whereas another one, Cinnacide, had the opposite effect of suppressing inflammation in the airways. The flavour, Banana Pudding, the study noted, exaggerated the level of tissue scarring.
The researchers also mentioned that all e-cigarette liquids containing nicotine suppressed airway inflammation, which was consistent with the known anti-inflammatory properties of nicotine. The study noted that the researchers didn't analyse the liquids directly, to confirm what they contained. However they worked based on evidence from previous research which categorised flavours as "buttery/creamy" and "cinnamon" -- which likely included Banana Pudding and Cinnacide -- are toxic.
According to the researchers, people should be cautious while promoting flavoured e-cigarettes to patients with respiratory disease such as asthma, and they added that policy makers should consider restricting the use of flavoured e-cigarettes.