Do restrictions on vaping flavours increase tobacco smoking? A systematic review says the evidence is not there.

Systematic Reviews rank highly
on the hierarchy of evidence

Will flavour bans cause vapers to return to smoking?

This post provides an update on research related to the potential benefits of allowing the sale of flavoured vaping products. The larger question of whether this belief is supported by evidence is discussed in a separate post.

Policy makers in Canada have faced claims that flavour bans will cause many vapers to return to smoking and fewer smokers to switch to vaping. These claims are often from companies which make vaping products, but are sometimes also from scientists who believe that governments should actively encourage smokers to switch to vaping products.

Until recently, policy makers had access to several competing studies addressing this question, but did not have any published structured reviews to assist them in assessing the overall state of evidence. To address this gap, U.S. researchers have recently published two reviews - a systematic review of research on whether smokers who use flavoured e-cigarettes are more likely to quit than are those who use tobacco- or unflavoured e-cigarettes, and a review of studies on what has happened or what might happen in communities where e-liquid flavours are restricted.

The results of these two papers are presented below. Importantly, they do not cover all of the evidence (they are restricted to English-language published studies, and exclude the extensive reports by governments, including by Health Canada. Notably, enthusiastic supporters of tobacco harm reduction and proponents of flavourings participated in the reviews. 

On the basis of these reviews, governments should not accept that  "flavours help smokers quit"  or that "flavour bans will increase smoking." The reviews instead conclude that:

• "[T]here is presently not enough evidence to determine whether flavored ENDS are superior to tobacco-flavored ENDS for smoking cessation" (Liber et al, 2023)
• "[T]he overall findings on the potential impact of a federal flavoured ENDS restriction are mixed and inconclusive." (Cadhem et al, 2023)

Flavour bans are spreading

Some health leaders have not been dissuaded by claims that flavour bans cause harm, and are instead pushing forward with measures to protect youth from experimenting with - and becoming regular users of - these harmful products. 

In recent weeks Quebec, Norway and Australia have all announced that e-liquid flavours will be banned and last week the U.S. Food and Drug Administration has ordered more flavoured products off the market. (Notably, in its product-by-product assessment, the U.S. FDA has not yet found public health benefit to any flavoured products.)

The majority of the world's children live in countries where flavoured e-cigarettes (or all e-cigarettes) are not permitted for sale.

Fact sheet: Restrictions on e-cigarette flavours

The Canadian context: a change of heart and a pivot in approach

The claims that flavour restrictions will cause harm to smokers have particular relevance to Canada federal policy. Despite prodding by some reporters and parliamentarians in the Senate and House of Commons, Health Canada continues to decline all opportunities to reaffirm its previous intention to ban flavourings in vaping liquids. 

The official reason given for the delay is that departmental officials continues to review "feedback from the more than 25,000 submissions it received through its consultations"  Given that all but 1,000 of those submissions were filed by Rights4Vapers, a group linked to the tobacco and vaping industry, this acknowledges that an industry front group succeeded in stalling regulations by the simple tactic of overwhelming the capacity of the consultation process. 

An alternative explanation for the apparent change of direction may be found in a recent pivot in Health Canada's approach to designing policies and programs related to tobacco use. The department's 2023-2024 workplan made public in February flagged a new approach to tobacco - described as a "person-centered approach to smoking cessation" based on "lived experience".  This shift was foreshadowed soon after Ministers Duclos and Bennett were appointed as ministers in November 2021. (The flavour restrictions had been announced by the previous Health Minister, Patty Hajdu, in June 2021). 

It is in this new context that vapers have been invited to meet with federal-policy makers, although the impact of those meetings on policy decisions has not been made public.

2023–24 Departmental Plan: Health Canada

Health Canada also announced a change to its approach to youth vaping. The department's "new" focus attributes mental health as the driver of youth vaping:  "The department is considering youth vaping within a broader multi-drug use landscape and its connection to mental health."

The impact of this shift in focus can be seen in the revisions to the department's work-plan, from which regulations on flavourings or other marketing have now disappeared.  Whereas two years ago the department said it would  "take further action to reduce the appeal of and access to vaping products among young Canadians - including new regulatory proposals," such plans have been dropped for the coming year.

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RECENT REVIEWS OF EVIDENCE ON THE IMPACT OF FLAVOUR RESTRICTIONS

1. The role of flavored electronic nicotine delivery systems in smoking cessation: A systematic review.
Liber AC, Knoll M, Cadham CJ, Issabakhsh M, Oh H, Cook S, Warner KE, Mistry R, Levy DT.
Drug Alcohol Depend Rep. 2023 Mar 16;7:100143. doi: 10.1016/j.dadr.2023.100143. PMID: 37012981; PMCID: PMC10066538.

This is the first systematic review of evidence on the impact of flavoured e-cigarette use on quit success. It provides policy-makers with a higher-certainty knowledge that there is insufficient evidence to suggest that flavourings in vaping liquids increase the likelihood that a smoker can use e-cigarettes to quit.

Using PRISMA guidelines, this team located 29 studies published before May 15, 2022 that looked at the impact of flavoured e-cigarettes on encouraging smokers to switch to vaping and on assisting them in stopping smoking. (These studies included some conducted on Canadian smokers by Canadian researchers).

Among the 22 publications that reported on differences in quitting success, only 9 found a statistically significant improvement in quit success among those who chose to use flavours in comparison with those who did not. Of these, at least two were conducted by tobacco industry consultants. 

Using the GRADE criteria for quality of evidence, these reviewers assessed the quality of these studies as "low" or "very low". They noted that these studies relied on self-reported outcomes, mostly did nto randomize the assignment of flavours and could not be adequately assessed for risk of bias.

As the reviewers put it: "there is presently not enough evidence to determine whether flavored ENDS are superior to tobacco-flavored ENDS for smoking cessation". Perhaps disappointed by this finding, they noted that this "could change in the future."

Click on image to enlarge
or see results here

2) The actual and anticipated effects of restrictions on flavoured electronic nicotine delivery systems: a scoping review.
Cadham CJ, Liber AC, Sánchez-Romero LM, Issabakhsh M, Warner KE, Meza R, Levy DT.
TBMC Public Health. 2022 Nov 19;22(1):2128. doi: 10.1186/s12889-022-14440-x. PMID: 36402989; PMCID: PMC9675183.

This review of studies measuring the impact of flavour restrictions ours had been restricted and also experimental studies with smokers that predicted what these outcomes would be. 

This review also used PRISMA guidelines and GRADE scores to select and assess studies published up until May 3, 2022 which helped answer the questions of whether flavour restrictions did or would be likely to decrease e-cigarette use or increase tobacco smoking. Of the 30 identified studies, 26 were conducted exclusively in the United States; 21 looked at what happened after restrictions were actually implemented  and 9 explored what might happen using psychological experiments or survey questions. Five studies used product sales to measure impact, 17 used reports on behaviour.  

This paper provides policy makers with a useful literature search, but does not give much guidance on what will happen if flavours are banned. The reviewers found that the 5 studies comparing the volume cigarette sales in U.S. cities and states which banned flavours produced inconsistent results (two found an increase, two found a decrease and one found no change). The ability of vapers to import products from neighbouring jurisdictions contributed to such evidence being assessed as low quality.

This review could not conclude that flavouring restrictions increased cigarette use. "The overall findings on the potential impact of a federal flavoured ENDS restriction are mixed and inconclusive."

Click on image to enlarge
or see results here

Six take-aways from Canada's student smoking survey

This past week Health Canada released the results of the most recent Canadian Student, Alcohol and Tobacco Survey, with data collected in selected schools across Canada (except New Brunswick) during the 2021-2022 school year. 

This is the most recent version of the school-based smoking and drug survey which has been conducted periodically since 1994. In recent years the survey covers students in grades 7 to 12. To focus on the health status of these young Canadians as they complete their public school years, many of the results discussed below are limited to those for the senior grades 10 to 12. An excel chart with the tables shown below can be downloaded here. 

CBC News coverage

Health Canada provides a useful summary of topline results - and the media has reported on the concerns raised about the continuing high rate of vaping that was produced by the survey.  

This post identifies 6 important take-away messages from these results.

1. Health Canada has not undone the damage of its 2018 policy change.

In May 2018, the federal government implemented a major policy change and allowed vaping products to be sold with few regulatory restrictions. The impact of those policies was immediate: past month e-cigarette use among senior high school students doubled between 2016-2017 and 2018-2019 (from 14.6% to 29.4%).

Beginning in 2020, the federal government began to restrict the market freedoms which it had initially extended to vaping companies. Most promotions were banned in the fall of 2020, nicotine concentration was capped at 20 mg/ml the following summer. Starting in 2019, provincial governments began to increase their own restrictions on the marketing of e-cigarettes (a summary of measures can be viewed here).

The student survey taken after these changes were in place shows a flattening of the curve, but there is no evidence that the harms caused by the 2018 policy change are being reversed. Past-month vaping by students in grade 10 to 12 has been reduced from 29.4% to 23.6%, and the frequency of daily vaping in this age group has remained at more than 1 in 10 students (11.8% in 2020-21, compared with 11.6 in 2018-19 and 2.2% in  2016-17).

The continuing high rate of vaping is particularly worrisome in the context of Health Canada's failure to implement other marketing restrictions. In June 2021, the government announced plans to restrict flavours in vaping products, but has seemingly walked away from that intention. In April 2021 it announced plans to curtail youth-friendly product designs, but abandoned these the following year. 

2. Many Canadian students think there are few risks to smoking or vaping

During last year's survey, more than 1 in 20 Canadian students (6.3%) perceive no risk of harm from smoking cigarettes on a regular basis -- twice as many as held that view in 2014-15. Roughly the same percentage hold this view about e-cigarettes (6.6%). In this case, the number who think regular vaping causes no risk has fallen in half, from 11.9% in 2014.

A large proportion (almost half) of students perceive little or no risk to using cigarettes or e-cigarettes once in a while. 

3. E-cigarettes seem to addict more quickly than cigarettes 

A much higher proportion of young people who ever try vaping become daily users before they leave school.

Among the senior high school students surveyed, the path from experimental to regular use appears faster or deeper for vaping products than for cigarettes. Over the past 8 cycles, an average of 1 in 10 senior high school students who ever tried cigarettes was using them daily at the time of the survey (from a low of 5% in 2018-19 to a high of 14% in 2008-09). This “conversion factor” can be calculated by dividing the number of daily users by the number of ever users and expressing the result as a percentage.

The rate of conversion to regular use of vaping products was much higher in the 3 cycles in which data that allows for this calculation to be made, growing from 5% in 2016-2017 to 29% in 2021-22.

4. Health Canada has now missed one of its three  tobacco control targets, but has not said how it will address this failing.

The federal government sets policy targets for its programs, and - as shown on Treasury Board's InfoBase - three such targets are set for Canada's Tobacco Strategy:

* smoking prevalence no greater than 5% by 2035 (as measured by CCHS) 

* past-month tobacco use by children in grades 7 to 12 no greater than 5% by March 2023 (as measured by CSTADS)

* past month e-cigarette use by children in grades 7 to 12 no greater than 5% by March 2023 (as measured by CSTADS). 

Because Health Canada delayed CSTADS by one year, there will be no measure of tobacco or e-cigarette use among students in March 2023. The data released for 2022 however show that the target for e-cigarettes has been exceeded by 1 in 20 children (16% instead of 10%).

Health Canada has not established a target for overall nicotine use by young people and surprisingly does not release an estimate of the number of students who use nicotine through either tobacco or vaping products. 

5. The steady decline in cigarette smoking pre-dates the availability of e-cigarettes.

Senior high school students (grades 10 to 12) were included in the survey for the first time in 2006-2007. Since then, the proportion of senior high school students who have never smoked a single cigarette has increased from one-half (52%) to more than three-quarters (78% in 2021-2022). During the same period, the number of students who were smoking each day or on an occasional basis fell by more than two-thirds (from 11.4% to 3.1%).

The label "current smoker" is applied only to those who have smoked more than 100 cigarettes (4 to 5 packs) in their lifetime. If those who have smoked in the past month but have not yet reached that amount are included, the percentage of senior students who are currently using tobacco increases to 6%. (3.1% who had moved past the experimental phase and were smoking on a daily or occasional basis and 2.9% who had smoked fewer than 100 cigarettes in their lifetime but had smoked in the past month). (CSTADS definitions are available here). 

6. Provincial flavour restrictions are not preventing youth from using flavoured e-cigarettes. 

Three Canadian provinces had flavour bans in place at the time of this survey: Prince Edward Island, Nova Scotia and New Brunswick. (New Brunswick did not participate in the survey). Three other provinces had restrictions which prohibited flavoured vaping liquids from being sold other than in specialty shops where young people are not allowed to enter.

The reported choices of students shows that these restrictions were not sufficient to prevent young people from having access to flavoured products. Among those who reported having a usual flavour, three quarters (75%) said they used a fruit flavour: this was only marginally lower in the provinces where such flavours were not permitted for sale. The second most frequently identified flavour category was mint-menthol (14% nationally). 

Nova Scotia, where only tobacco-flavoured liquids are permitted for sale, was the only province with a reportable number of students who said they usually used tobacco flavourings - fewer than 1 in 20 (4%).

The growing population of never-smoking vapers

The students who spent an hour of classroom time answering the CSTADS survey last year are the first generation of Canadians who entered high school after e-cigarettes were legalized in Canada. From this new cohort alone, there are 360,000 school children who are vaping, and 174,000 who already do so every day. By the time the next school surveys are taken, many of these children will no longer be included - although they will be captured by surveys like the Canadian Tobacco and Nicotine Survey (CTNS), which will describe them as the "young adults" that they have grown into -- allowing policy makers and tobacco-nicotine companies to suggest that such nicotine use reflects a choice made after the duty of the state and manufacturer to protect young people from these products has ended.  

The effect of the aging-out of youth vapers is already apparent in the CTNS surveys. The results to winter 2021 are shown below, with the winter 2022 results likely to be released this summer.

We should acknowledge that each successive cohort of children recruited into vaping adds to the number of Canadians injured by the policy decision to allow tobacco companies to promote and supply vaping products as consumer goods. These young people (and as the adults they will soon be) are the collateral damage in a poorly designed harm reduction approach. The damage will grow until the policy is changed. 

Bans on flavourings and youth-friendly designs are urgently required, as are meaningful barriers to youth access. Equally important is the need for Canada to re-think its approach to managing nicotine supply. The CSTADs results are another indication that Canada's tobacco harm reduction approach is not working.