1. The review
This evidence review is the eighth in a series of independent reports on vaping originally commissioned by Public Health England and now by the Office for Health Improvement and Disparities in the Department of Health and Social Care.
This report was led by academics at King’s College London with a group of international collaborators and is the most comprehensive to date. Its main focus is a systematic review of the evidence on the health risks of nicotine vaping.
2. Health risks
The report primarily looks at data on human exposure to vaping, complemented with findings from animal and cell studies. It provides the most robust evidence on health risks of vaping to date. It also assesses the relative risks of vaping compared with smoking, as well as the absolute risks of vaping compared with not vaping or smoking.
2.1 Overall conclusions
Based on the evidence that the team reviewed, the conclusions were that:
- in the short and medium term, vaping poses a small fraction of the risks of smoking
- vaping is not risk-free, particularly for people who have never smoked
- evidence is mostly limited to short and medium term effects and studies assessing longer term vaping (for more than 12 months) are necessary
- more standardised and consistent methodologies in future studies would improve interpretation of the evidence
2.2 Biomarkers of toxicant exposure
Biomarkers of toxicant exposure are measurements of potentially harmful substance levels in the body. The evidence reviewed suggests there is:
- significantly lower exposure to harmful substances from vaping compared with smoking, as shown by biomarkers associated with the risk of cancer, respiratory and cardiovascular conditions
- similar or higher exposure to harmful substances from vaping compared with not using nicotine products
- no significant increase of toxicant biomarkers after short-term secondhand exposure to vaping among people who do not smoke or vape
2.3 Biomarkers of potential harm
Biomarkers of potential harm are measurements of biological changes in the body due to an exposure to smoking or vaping. Although this review looked at many studies of biomarkers of potential harm, the team could draw only limited conclusions. However, better-run studies assessing short and medium term risks, found no major causes of concern associated with vaping.
3. Smoking and vaping prevalence
3.1 Young people
The latest data from the ASH-Youth 2022 survey of 11 to 18 year olds in England show that:
- current smoking prevalence (including occasional and regular smoking) is 6% in 2022, compared with 4.1% in 2021 and 6.7% in 2020
- current vaping prevalence (including occasional and regular vaping) is 8.6% in 2022, compared with 4% in 2021 and 4.8% in 2020
- most young people who have never smoked are also not currently vaping (98.3%)
- use of disposable vaping products has increased substantially, with 52.8% of current vapers using them in 2022, compared with 7.8% in 2021 and 5.3% in 2020
3.2 Adults
The latest data from several national studies of adults in England shows that:
- smoking prevalence in England in 2021 was between 12.7% and 14.9% depending on the survey, which equates to between 5.6 and 6.6 million adults who smoke
- vaping prevalence in England in 2021 was between 6.9% and 7.1%, depending on the survey, which equates to between 3.1 and 3.2 million adults who vape
- vaping prevalence among adults who have never smoked remained very low, at between 0.6% and 0.7% in 2021
- the popularity of disposable vaping products has increased among adults who vape, with 15.2% using them in 2022 compared with 2.2% in 2021
- tank type products remained the most popular vaping devices (used by 64.3% of adult vapers in 2022)
- vaping products remain the most common aid used by people to help them stop smoking
- in stop smoking services in 2020 to 2021, quit attempts involving a vaping product were associated with the highest success rates (64.9% compared with 58.6% for attempts not involving a vaping product)
- the stop smoking service data are consistent with the latest evidence from the Cochrane living systematic review on electronic cigarettes for smoking cessation which also shows vaping is effective for stopping smoking
4. Flavours
Fruit flavours remained the most popular among adults and young people who vape, followed by ‘menthol/mint’.
Overall, there is a lack of evidence on whether flavourings affect health risks. Vaping products that contain the flavouring chemical cinnamaldehyde are a cause of concern, and regulatory bodies should review its use in e-liquids.
There is limited evidence that some flavourings in vaping products have the potential to alter cellular responses (from animal and cell studies), but less than exposure to tobacco smoke.
5. Nicotine
Vaping products generally provide lower nicotine levels to users than smoking does. However, people who are experienced vapers can achieve nicotine levels similar to people who smoke.
Existing evidence suggests that the risk and severity of nicotine dependency from vaping is lower than for smoking but varies by product characteristics (like device type and nicotine concentration in e-liquids). This is consistent with evidence on nicotine exposure from biomarker and pharmacokinetic studies from the current review.
6. Harm perceptions
In 2021, only 34% of adults who smoked accurately believed that vaping was less harmful than smoking. Only 11% of adults who smoked knew that none or a small amount of the risks of smoking were due to nicotine. Inaccurate perceptions need to be addressed.
The evidence reviewed also suggests that:
- people’s perceptions about vaping harms can influence their subsequent vaping and smoking behaviour
- communicating accurate information about the relative harms of vaping can help to correct misperceptions of vaping, particularly among adults
Interventions on absolute harms of vaping that aim to deter young people need to be carefully designed so they do not misinform people (particularly smokers) about the relative harms of smoking and vaping.