The popularity of e-cigarettes continues to increase, with more Canadians than ever using them indoors and out. The scientific evidence on e-cigarette vapour toxicity and its health effects for both users and bystanders is still emerging and does not yet represent a robust body of knowledge. Unlike the homogeneity of cigarettes, e-cigarettes are available in a wide array of formats, and together with dozens of different e-juice brands and flavours, there are literally thousands of possible combinations to study. Currently, many countries including Canada do not have legislated manufacturing standards in place for vaping products, which means a lack of consistency and quality control adds to the challenges of studying and definitively establishing risk for vaping products. To further complicate matters, some studies on ecigarette vapour toxicity use machines in laboratories and others use humans vaping under real-use conditions. Laboratory studies may not reflect actual exposures during use because machine vaping may not accurately represent human vaping behaviour and duration, and because many users custom mix their own vaping solutions.
Moreover, many e-cigarette studies have been deemed to be of low quality and there are relatively few studies that have looked at secondhand vapour specifically. As a result, it is difficult to make comparisons between studies and to draw firm conclusions about what is typically present in e-cigarette vapour, let alone what the long-term health effects of exposure to bystanders might be.
