E-cigarettes alter lungs at cellular level

New research shows that e-cigs -- or more specifically, the flavourings that can be used in them – could have a dramatic impact on the human body. A report published by the American Thoracic Society, which focuses on pulmonary diseases and breathing disorders, has found they can actually alter lung function at the cellular level.

The findings were presented at the 2015 American Thoracic Society International Conference and include changes in cell viability, cell proliferation, and calcium signalling, though these effects were dependent on which flavour liquid was used in the trials. 

The study uses cultures of human airway epithelial cells, which were exposed to various doses of 13 e-cigarette flavours for either 30 minutes or 24 hours. In the former, three flavours -- Hot Cinnamon Candies, Banana Pudding (Southern Style), and Menthol Tobacco -- saw a dose-dependent calcium response. At higher doses, they were actually toxic to the cells. In the 24-hour exposure test, the same flavours decreased cells' ability to grow and replicate, depending on the dosage administered.

"The effects of the various chemical components of e-cigarette vapor on lung tissue are largely unknown," said the study's lead author, Temperance Rowell of the University of North Carolina. "In our study using human lung epithelial cells, a number of cell viability and toxicity parameters pointed to five of 13 flavours tested showing overall adverse effects to cells in a dose-dependent manner."

However, the toxic effects were not seen with either nicotine or the e-liquid vehicle, which consisted of the usual propylene glycol or vegetable glycerin. Longer term studies, including the "aerosolised product of e-liquid flavours on cultured primary human bronchial epithelial cells" are ongoing.

While it might seem a no-brainer to some that intentionally inhaling largely unregulated chemicals may have some negative health side-effects, there is comparatively little research into the long-term impact of either the "regular" nicotine delivery systems of e-cigs or the flavoured alternatives. Similarly, there is minimal oversight of the vapourisers or liquids -- Rowell's study used flavoured liquids from an American specialist retailer, though the ones UK consumers may purchase could come from a variety of different sources, all with different production standards, ingredients, and chemical compositions. However, a World Health Organisation report from 2013 concluded that "consumers should be strongly advised not to use any of these products, including electronic cigarettes", and countries including Brazil, Uruguay, and Singapore have banned them.

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