Abstract
Electronic cigarettes have a signature of harm in the lung that challenges the concept that switching from cigarettes to e-cigarettes is a healthier alternative http://bit.ly/2Z3Ahdu
From the author:
We thank R. Emma and colleagues for their interest in our preclinical study to investigate the effects of e-cigarettes on the lung. Our study was initiated from clinical observations that children exposed to second-hand e-cigarette vapour at home and undergoing surgery have a longer recovery and healing time than children from a non-smoking environment. For this reason, our animals underwent whole body (or so called second-hand smoke) exposure to e-cigarette vapour.
We must clarify that the whole body exposure is very different from direct inhalation and the number of puffs delivered into the 32-m3 exposure chamber in experimental conditions were comparable to the use of electronic cigarettes and tobacco cigarettes by people.
The amount of nicotine used for injections was based on previous studies to produce stable plasma nicotine levels of approximately 25 ng·mL−1, which is comparable with plasma levels (in the 10–50 ng·mL−1 range) of habitual smokers [1, 2]. In our study nicotine was injected as nicotine di-tartrate salt. Thus, the actual dose used was below high toxicity levels [2] and we believe that our data are highly informative of the nicotine effects in humans under normal conditions of consumption.
We closely monitored animal health during the 35-day exposure period and, as anticipated, animals exposed to cigarette smoke lost close to 15% of the body weight when compared to room air exposed controls. The same body weight loss was observed in animals exposed to e-cigarette vapour or subjected to nicotine injections. We documented the adverse effects of e-cigarette exposure by lung pathology [3] and by skin necrosis in a skin flap survival model in vivo [4]. In a skin flap survival model, we showed that exposure to e-cigarette vapour produced damaging effect on skin microcirculation and interfered with the healing process. Our findings suggest that e-cigarette exposure is harmful not only to the lung, but also to the skin microcirculation.
We believe that our study on the adverse effects of e-cigarettes merely touches on the tip of the iceberg. New emerging studies in animal models and cell cultures show that flavourings alone used in e-juices can trigger an inflammatory response in monocytes, mediated by ROS production, endothelial dysfunction, DNA damage and induction of apoptosis in endothelial and epithelial cells. These studies provide insights into potential pulmonary toxicity and tissue damage in e-cigarette users [5–10].
It is premature to draw longitudinal conclusions from a prospective 3.5-year study of non-smoking daily e-cigarette users [11]. More studies are urgently needed regarding the public health consequences of e-cigarettes; so far, the scientific body of evidence on the health effects of e-cigarettes is very limited [12, 13]. Alarmingly, e-cigarette use from 2017 to 2018 increased 78% among high school students (11.7% to 20.8%) and 48% among middle school students (3.3% to 4.9%) from 2017 to 2018 [14], and poisoning events leading to emergency room visits related to liquid nicotine in electronic nicotine delivery systems in young children have been on the rise [15].
We strongly believe that considering recent discoveries the regulatory policy recommendations for humans based on preclinical studies are highly valuable. Due to the much longer life span, humans experience toxic effects after decades of smoking, while preclinical animal models, due to a much shorter time scale, usually demonstrate the first warning signs of possible adverse effects of e-cigarette vapour to human health.
Our data show that e-cigarettes have a signature of harm in the lung that challenges the concept that switching from cigarettes to e-cigarettes is a healthier alternative.
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Supplementary Material
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Footnotes
Conflict of interest: L. Taraseviciene-Stewart has nothing to disclose.
- Received July 18, 2019.
- Accepted July 18, 2019.
- Copyright ©ERS 2019