A recent study by researchers at the University of Florida has found that the mouthpieces of many e-cigarettes and vape pens are heavily contaminated with potentially harmful fungi. The findings, currently published as a preprint on the bioRxiv server, raise new concerns about hygiene and respiratory health risks associated with vaping.
The research team examined the surfaces of vape mouthpieces and discovered that they were “abundantly colonised” by various fungal species. The study identified fungi including Rhodotorula, Aureobasidium, Cystobasidium, and Meyerozyma. These were not necessarily fungi that typically inhabit the human mouth, suggesting that the contamination likely originated from environmental exposure or inadequate cleaning. One of the most significant discoveries was the prevalence of Cystobasidium minutum, a yeast-like fungus. Laboratory experiments conducted on mice indicated that inhalation exposure to this organism could lead to mucus overproduction and signs of obstructive lung disease, resembling chronic bronchitis. The affected mice showed marked respiratory inflammation, highlighting a potential pathway by which contaminated mouthpieces might impact lung health.
The study is particularly notable because much of the existing research into vaping health risks has focused on the chemical content of e-liquids and aerosols, such as nicotine, flavourings, and toxic compounds released during heating. Less attention has been given to the microbiological contamination of vaping devices, despite the fact that mouthpieces come into direct and repeated contact with the user’s mouth and are often stored in environments that could promote microbial growth. The researchers stress that while their experiments provide strong evidence of fungal presence, the study is still at the preprint stage and has not yet undergone peer review. This means the findings should be interpreted with caution until they are validated by further studies. Moreover, the harmful effects were observed in animal models, so direct evidence in human vapers is not yet available.
Nonetheless, the implications are concerning. The detection of fungi capable of inducing respiratory problems in mice suggests a potential, if unconfirmed, risk to human users. For people who vape regularly, especially those with weakened immune systems or pre-existing respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD), fungal contamination could pose an additional health hazard.
The research also raises broader questions about hygiene practices among vape users. Many individuals may not clean their devices regularly, allowing saliva, environmental particles, and microbes to accumulate. Unlike conventional cigarettes, which are disposed of after use, vape devices and their mouthpieces are reused repeatedly, increasing the opportunity for contamination. Cleaning and maintenance recommendations for vaping equipment vary, and there is little formal guidance on preventing microbial build-up. The study’s findings may prompt calls for clearer advice from public health authorities and manufacturers, including the potential use of antimicrobial materials in mouthpiece design or more explicit instructions for regular sanitisation.
The vaping industry is likely to face renewed scrutiny as research into microbial contamination expands. While some manufacturers have introduced features aimed at preventing e-liquid leakage or overheating, microbial safety has not been a primary focus. This study suggests it may need to become one. As vaping continues to be promoted as a less harmful alternative to smoking, emerging evidence such as this highlights the importance of considering all aspects of device safety. Chemical risks have dominated the discussion so far, but microbial risks could represent an overlooked area of concern. Until more is known, experts recommend that users adopt good hygiene practices, including regularly cleaning mouthpieces, avoiding device sharing, and storing vapes in clean, dry environments.
