Jinsong Chen, Chris Bullen, and Kim Dirks
Int. J. Environ. Res. Public Health 2017, 14(4), 382
Source DOI: 10.3390/ijerph14040382
Background: Although some studies have identified hazardous substances in electronic cigarette (EC) liquids and emissions, there is limited information about the health risks of using ECs.
Methods: In this study, the U.S. Environmental Protection Agency (EPA) health risk assessment model and findings of a literature review were used to determine and profile hazards. Focus was put on the toxicants reported in the literature on conventional cigarette (CC) smoke that most strongly associated with adverse health effects. To evaluate their health risks, dose-response relationships and standard-use conditions were used to estimate average hazard exposures and to calculate the overall health risks of ECs and CCs, benchmarked against international guideline levels for each hazard.
Results: Four hazards (acrolein, diethylene glycol, propylene glycol and cadmium) reported in EC emissions and seven hazards (acetaldehyde, acrolein, formaldehyde, cadmium, CO, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosonornicotine (NNN)) reported in CC emissions had maximum exposure levels higher than the guideline levels. Two hazards (acrolein, propylene glycol) in EC emissions and five hazards (acetaldehyde, acrolein, formaldehyde, cadmium, NNN) in CC emissions had average exposure levels higher than the guideline levels.
Conclusions: Based on the conditions of use, ECs should be a safer nicotine-delivery product than CCs.
Our findings provide evidence that supports the Public Health England statement but was arrived at by applying a different methodology. Although we are aware that some smokers had been smoking for decades, the main purpose of this study is to explore whether they will be exposed to a lower risk of harm by changing to vaping. Hence, no matter how long a smoker had smoked, the probable benefits of changing his/her source of nicotine consumption from CCs to ECs for a year should be very similar. This study leads to two conclusions: that the use of ECs presents a lower risk to health than the use of CCs, and that ECs are likely to be of low health risk to the user.
These results must be interpreted with caution: firstly, CCs have been used for more than a century and there are many more CC users than EC users worldwide. Therefore, far more information is available about the harms of CCs in regard to all criteria listed in the MCDA model. In contrast, ECs are very new products with far fewer users and have limited data available on long-term health consequences. This makes it difficult to assign scores to ECs in relation to criteria, such as product-specific mortality/morbidity and product-related mortality/morbidity. Therefore, the scores for ECs are likely to be less accurate and more biased towards lower risk levels than for CCs. Secondly, there were a number assumptions in our analyses: The daily consumption of CCs and ECs was assumed to be 11 cigarettes or a corresponding 11 vaping sessions over one year; the EC and CC usage patterns in the reviewed studies were assumed to reflect real world use patterns; all ECs and CCs were assumed to be similar in their ability to expose users to various hazards and to those tested in the reviewed studies; fourthly, we restricted our assessment to only 12 hazards and three groups of adverse health effects associated with exposure.
The findings of this study have different implications for different groups of people. For smokers, quitting smoking altogether is very likely to lead to great health benefits. However, ECs could be a safer substitute for CCs for those in the process of tobacco cessation.
For current EC users, it is important to be aware that using some low quality EC products may expose them to a higher risk of harm. EC brands and products with more rigorous quality authentication should be selected. Currently, regulations on EC manufacturing standards and quality are few and far between. Standards for ECs quality and contents should be introduced to prevent low-quality ECs from being sold.
Some health professionals are unclear whether they should recommend ECs to their patients who are smokers. For those patients unable to fully quit smoking or those who refuse to use approved nicotine replacement therapy, ECs could be recommended as an option to reduce exposure to the hazards in CC smoke.
Standardised methods for assessing EC exposures are needed. By setting standard EC usage patterns (e.g., puff volume, puff frequency, puff duration, puff number per session and so on) and standard EC hazard exposure assessments (e.g., hazard detection limits), EC hazard exposure levels could be compared between different studies. In addition, by setting detection limits in smoking/vaping simulation tests, the hazard exposure levels in EC or CC emissions could be determined more accurately.
The health effects of using ECs are still not well understood, but current evidence points to ECs being less harmful than CCs. Using ECs to replace CCs as nicotine delivery products could lead to millions of lives saved and significant reductions in the burden of many smoking-related diseases.