E-Cigarette Respiratory Health: An Interview with Prof Riccardo Polosa
Professor Polosa recently completed his latest study, a review of the effect of vaping on respiratory health. We sat down with Riccardo Polosa to discuss how vaping can reverse harm, its potential to reduce infections, the latest debate on vaping and respiratory illnesses in the US, and more.
In a recent press release, you reiterated that e-cigarette smoking is at least 95% safer and possibly more than 95% safer than smoking regular combustible cigarettes. As you said, nobody can prove that e-cigarettes are 100% safe because we don't have very long-term data. How confident can we be about the 95% safer figure?
Public Health England reiterated this finding in their evidence update from the previous year (2018). Stating that vaping is at least 95% less harmful than smoking continues to be a good way to communicate the huge difference in relative risk, based on current toxicological evidence. It has been shown that vape aerosol contains much fewer toxins compared to cigarette smoke, and – most importantly – the levels of toxins detected in vape aerosol are significantly lower than those from tobacco smoke, often several orders of magnitude lower (10 times lower).
In your study, you mention that long-term studies based on the analysis of medical records are needed. How close are we to achieving this?
The collection of patient records varies greatly between countries. In addition, patient records should report that a person is vaping, how much, and for how long, and include the same information about smoking or other tobacco use. This may be available in some countries now or in the near future, but for others, it will never be possible.
Research based on access to medical records is difficult due to ethical and privacy concerns, but where reports are available, studies can provide a key to understanding the long-term effects of vaping. Another way we can control the long-term effects of vaping is the science of epidemiology. As fewer people smoke, we hope to see a reduction in tobacco-related diseases (respiratory, cardiovascular, and cancers) over time. Using mathematics, we can apply population estimates of the number of vapers to the number of reports of smoking-related diseases to observe correlations.
You also stated the need for studies looking at the effect of **e-cigarette products** on people who have never smoked to separate the negative effects of e-cigarette use from existing harms caused by combustible cigarettes. Given the number of never-smokers who regularly smoke, how easy would it be to find these people and how realistic would it be to conduct a large-scale study?
Finding someone who has never been exposed to cigarette smoke is like the proverbial needle in a haystack. However, well-coordinated multinational efforts can gather study populations large enough to answer important research questions about the long-term health effects of **e-cigarette use**. This is the only way. We are lucky enough to have qualified for a generous research grant from a Smoke-Free World Foundation.
Your previous research suggested that e-cigarettes can help reverse some smoking-related diseases.
In this review, it is particularly interesting to see that smokers suffering from COPD experienced an improvement in health when ex-smokers who quit did not usually experience an improvement. Why do you think this is?
Simple. When interpreting these studies, it is important to understand the distinction between ex-smokers with a smoking-related disease and ex-smokers with no medical conditions (or who have not yet developed any). It is relatively easy to show improvements in quitters who have an abnormal baseline (those who have already damaged their health by smoking) – and I call this harm reversal. In contrast, relatively healthy smokers already have a normal/healthy baseline, so there is no room for improvement. For relatively healthy smokers, the benefit is in leaving the ability to reduce their risk of developing a smoking-related disease in the future – and this is risk reduction.
How beneficial do you think the anti-bacterial and anti-viral properties of propylene glycol in e-liquid can be?
PG in aerosol form has long been known as an effective antibacterial and antiviral agent and will likely effectively prevent respiratory infections. Therefore, rather than creating an ideal situation for microbes to proliferate and spread, PG vaping can help users combat all kinds of bacteria, viruses, and common infections (e.g., common cold, tonsillitis, gingivitis). Moreover, daily vaping can be a practical way to prevent respiratory exacerbations associated with diseases such as asthma and COPD. This is a thesis, not definitive information, but there are encouraging aspects for **e-cigarette users** in this situation.
As you noted in the article, technology contributes to an improvement in the safety of **e-cigarette** devices, especially by mentioning automatic temperature control. Where should manufacturers focus their efforts to further improve **e-cigarette** safety?
Temperature regulation is crucial. However, it is only one aspect of technological advancement in e-cigarette design. Manufacturers should invest in next-generation batteries that can deliver power in the safest possible way and develop new formulations that can guarantee maximum satisfaction from fewer chemicals. Ease of filling and overall ease of use are important features. It is not recommended to use the same vaporization unit (cartridge - coil) for too long.
In the UK, over the last few years, a lot of effort has been put into improving the safety of e-liquid by identifying and eliminating potentially harmful components in e-liquids. How much can this work contribute to improving the safety of vaping?
Different flavors have different chemical profiles and therefore different toxicity levels. **E-cigarette users** should ensure that liquids are tested and comply with existing quality/safety guidelines. Concerns about poor quality/safety products are currently being addressed by the Technical Committee of the European Standardization organization (CEN TC437) for e-cigarettes and e-liquids.
However, when looking at the highest priority for safer **e-cigarette use**, careful toxicological characterization and risk assessment of flavors in vape aerosols immediately come to mind. We recently published a revised draft proposal for a study that aims to create a toxicological database of common flavors on the market and potentially determine upper limit thresholds for the use of certain components. Aerosols will be tested using “chip on cell” technology, which is a more cost-effective method of understanding the toxicological effect of flavors in vitro.
Your literature review sometimes seems like a catalog of mistakes made by researchers. These include exposing animals to much higher concentrations of e-cigarette emissions than cigarette emissions in comparative tests, not adjusting for the weight of the animals used in the research, and not using a control group. Why are there so many problems in studies on electronic cigarettes? Is this simply due to poor standards, or are the standards deliberately manipulated to support the desired outcome?
There is no manipulation here. **E-cigarette** product research is quite new, and therefore researchers have had to make their own judgments about appropriate tests. As a result, most research designs are inadequate or not based on pharmaceutical tests where overdose is a common procedure.
Additionally, when investigating the impact of real-world interventions and epidemiology, conventional study designs are not fit for purpose, and it is difficult to reconcile more appropriate study designs with good scientific principles. Last but not least, sometimes the problem is a lack of sufficient funding for testing equipment, so researchers use what is available, even if it is less valid or reliable. It goes without saying that this area of research needs urgent critical review and reform.
You also mentioned some encouraging initiatives to standardize research methods in the field of e-cigarettes. Do you think these are developing well?
Absolutely. For example, ISO (International Organization for Standardization) is establishing test standards for **e-cigarette** machines and the analytical chemistry of vape aerosol components. In addition, we are about to conduct a series of reviews on the quality of research techniques, as well as the one recently published that addresses the quality of research in the respiratory field.
By discussing the issues and shortcomings with the numerous current research articles in the field, we plan to prepare a set of guidelines and frameworks for better quality in tobacco and vaping research. The framework is envisioned to be used by journal editors as a best practice code or checklist for future research articles. Researchers want to use best practices.
We have recently seen reports of vaping seizure cases in the US and UK. In the UK, it is clear that these are linked to vaping illegal drugs, but this is less clear in the US. What is behind these seizures, how concerning are they, and how do they fit with the findings of your research?
Surprisingly, very little research has been done on nicotine use and seizures in tobacco or vaping individuals. Animal studies are not applicable to humans in this situation. US reports do not document the substance(s) these people were vaping, and awareness of vaping other drugs appears low in the US (and elsewhere). Self-reporting of illegal drug vaping in the US may be low because disclosure could lead to arrest or refusal of payment for emergency services. Where clusters of seizure reports have occurred, it suggests a common source. In addition, no other adverse event registry has reported an increase in seizure incidence.
Finally, what would you say to a smoker who is considering switching to vaping but is concerned by media reports of the dangers of vaping?
The media's job is to make headlines and stories. What you need is accurate and good information about **e-cigarettes**. You have the right to know that vaping is much less toxic than smoking. Public Health England has done a lot of research on their findings that e-cigs are much less harmful. It is generally accepted in the research community that e-cigarettes are much less toxic than continuing to smoke.
To achieve the most risk reduction, a vaper should completely quit smoking at a reasonable time. As we know in harm reduction, substitution is easier to achieve than avoiding it. Even smoking 2 or 3 cigarettes a day carries about half the cancer risk of smoking 20 cigarettes a day.
I would also add that vapers should vape with moderation and stress that extreme forms of vaping (e.g., cloud chasing, excessive daily e-liquid consumption) should be avoided due to the increased potential health and safety risks.
