Improving on estimates of the potential relative harm to health from using modern ENDS (vaping) compared to tobacco smoking.

Introduction:
This article provides an analysis of the potential relative harm to health from using modern Electronic Nicotine Delivery Systems (ENDS) compared to tobacco smoking. The study identifies biomarkers associated with different disease groupings and conducts a review of recent studies comparing these biomarkers between people exclusively using ENDS and those exclusively smoking tobacco. The percentage differences in these biomarkers are used as a proxy for the assumed percentage difference in disease harm between ENDS and smoking.

Key Points:
- The study identified biomarkers specific to disease groupings: Volatile Organic Compound (VOCs) for chronic obstructive pulmonary disease (COPD), tobacco-specific N´-nitrosamines (TSNas) and polycyclic aromatic hydrocarbons (Pahs) for all cancers, and carbon monoxide and the VOC, acrolein, for cardiovascular disease (CVD).
- a review of recent studies (post January 2017) comparing these biomarkers between people exclusively using ENDS and those exclusively smoking tobacco was conducted.
- The percentage differences in biomarkers were assumed to reflect the percentage difference in disease harm and were applied to previously modelled estimates of smoking-related health loss (in health-adjusted life-years; haLYs) to produce disease-group-specific and overall estimates of health loss for ENDS use versus tobacco smoking.
- The respective relative biomarker levels (ENDS vs smoking) were: 28% for respiratory diseases, 42% for cancers, and 35% for CVD.
- When integrated with the haLY impacts by disease, the overall harm to health from ENDS was estimated to be 33% that of smoking.
- The study suggests that the use of modern ENDS devices (vaping) could be a third as harmful to health as smoking in a high-income country setting.
- The estimate is based on a limited number of biomarker studies and is best be considered a likely upper level of ENDS risk given potential biases in the method.

Main Message:
The study provides an updated estimate for relative harm of ENDS use compared to smoking by conducting a review of recent biomarker data. The analysis suggests that the harm associated with modern ENDS is 33% of the harm associated with tobacco smoking. however, this estimate should be considered a likely upper level given potential biases in the method. The study highlights the need for further research to develop a much stronger evidence base to inform the regulation of ENDS and smoking.

Wilson N, Summers Ja, ait Ouakrim D, hoek J, Edwards R, Blakely T. Improving on estimates of the potential relative harm to health from using modern ENDS (vaping) compared to tobacco smoking. BMC public health. 2021;21(1):2038. doi:10.1186/s12889-021-12103-x