E-cigarettes an evidence update A report commissioned by Public Health England

E-cigarettes: an evidence update10. Safety of e-cigarettes in the light of newevidenceIntroductionPHE commissioned a review of EC in 2014, which covered EC safety [131]. The reviewfound that the hazard associated with use of EC products currently on the market “islikely to be extremely low, and certainly much lower than smoking” and “the health risksof passive exposure to electronic cigarette vapour are likely to be extremely low”.These conclusions tally with a review by an international team of experts, whichestimated the risks of vaping at less than 5% of the risks of smoking [10] and acomprehensive review of relevant literature by another international team whichconcluded that “EC aerosol can contain some of the toxicants present in tobaccosmoke, but at levels which are much lower. Long-term health effects of EC use areunknown but compared with cigarettes, EC are likely to be much less, if at all, harmful tousers or bystanders” [132].Over the past few months, however, several reports have suggested that EC may posemore risks than previously thought [133-137].We were asked to review these studies to see if in the light of this new evidence, theconclusions of the PHE 2014 review need to be adjusted. We present below the detailsof these studies together with any additional data that may assist with theirinterpretation.Aldehydes in vapour from e-cigarettesTwo recent reports raised a possibility that under certain conditions, EC may releasehigh levels of aldehydes. Aldehydes, including formaldehyde, acrolein andacetaldehyde, are released in tobacco smoke and contribute to its toxicity. Aldehydesare also released with thermal degradation of propylene glycol and glycerol in e-liquids.Previous studies detected the presence of aldehydes, especially formaldehyde, in thevapour from some EC, but at levels much lower than in cigarette smoke [138]. Acrossbrands, EC released 1/50 th of the level of formaldehyde released by cigarettes. Thehighest level detected was six times lower than the level in cigarette smoke [138].In November 2014, following a press release from Japan [136], major media around theworld reported variations of a headline: “E-cigarettes contain 10 times the carcinogensof regular tobacco”. This was based on a Japanese researcher reporting at a pressconference that during tests on a number of EC brands, one product was identified76