Top 9 Studies on E-Liquid You Need to Know About
It goes without saying that there is a lot of controversy about e-cigarettes and e-liquids. With new scientific evidence emerging regularly, we’re finding out more and more each month, but there is an inherent tendency for benefits to be swept aside in favor of exaggerated portrayals of potential risk in the media.
If you’re finding yourself unsure what to think about the state of the science on e-liquid, learning more about some of the most important studies conducted to date gives you an objective picture of what we know and what we still need to find out.
Here are 9 studies addressing e-liquid (or closely-related issues) that you need to know about.
9 – Peering Through the Mist – the Chemistry of E-Cigarettes
This paper, written by Igor Burstyn and funded by CASAA, provides a systematic review of the evidence on the chemistry of the aerosol (i.e. the “vapor”) produced from e-liquids. The research compared the levels of chemicals to “threshold limit values” (TLVs), which are internationally-recognized workplace exposure limits designed to minimize risks to employees. The findings showed that almost all chemicals given off by vaporized e-liquids resulted in an exposure much lower than 1 percent of the TLV, with acrolein and formaldehyde exposure being less than 5 percent of the TLV, suggesting that e-liquids are very low in risk from a chemical perspective. The author found that only exposure to the main ingredients, PG and VG, may warrant concern, primarily due to the lack of established toxicity for these chemicals (although they’re generally recognized as safe).
8 – How Addictive Are E-Liquids?
Researchers on this study aimed to determine how addictive e-cigarettes are in comparison to tobacco cigarettes and nicotine gum. The study showed that those using nicotine-containing liquids were slightly more addicted than those using no-nicotine e-liquids, and that – among former smokers – long-term vapers (defined as use for over three months) were less addicted to e-cigarettes than long-term nicotine gum users were to the gum. For short-term users, there was little difference between gum users and vapers. Dual users (who both vaped and smoked) were generally less addicted to e-cigs than smokers who didn’t vape were to cigarettes.
7 – Do E-Liquids Poison More People Than Cigarettes?
This study used data from U.S. poison control centers to determine whether e-liquid poisonings were a concern, particularly in comparison to cigarette poisonings. Over the studied time period, exposures to e-cigs and e-liquids increased from one per month in September 2010 to 215 per month in February 2014, but cigarette-related exposures were consistently higher, ranging from 301 to 512 calls per month. For cigarettes, the vast majority of potential poisonings (since not all calls represent serious poisonings) were in 0 to 5 year olds (around 95 percent of calls), but this age group only accounted for 51 percent of calls related to e-cigarettes. Overall, e-cigarette poisonings increased, but are still dwarfed by cigarette-related calls and those from other household substances.
6 – Do E-Liquid Flavors Attract Non-Smoking Teens to Vaping?
This study set out to address the widespread concern that e-liquid flavors such as bubblegum will attract teens who otherwise wouldn’t smoke to vaping. The researchers compared the level of interest in trying e-cigarettes with a specific flavor of liquid to the level of interest in trying the same flavor when attached to bottled water or ice cream, comparing non-smoking teens with smoking adults and ranking interest in trying on a 0 to 10 scale. For non-smoking teens, the average level of interest in e-cigarettes was 0.41 (very low), and this didn’t significantly vary according to flavor. Adult smokers’ interest was higher and did significantly vary by flavor. This study suggests that e-liquid flavors don’t lure otherwise non-nicotine-consuming youth into vaping, despite concerns, but may pique the interest of adult smokers.
5 – Should Vapers Be Worried About Inhalation of Flavor Chemicals?
This study involved looking at the levels of flavoring chemicals in a sample of 30 e-liquids. The results showed that the majority of tested e-liquids contained less than 1 percent flavorings by weight, with 2 e-liquids containing more than 3 percent flavorings. Of the 24 identified chemicals, 6 of them were aldehydes, known to be primary irritants of the respiratory tract (although this doesn’t necessarily indicate a health risk). The researchers also noted that the majority of the tobacco-flavored e-liquids studied used confectionary flavor chemicals rather than tobacco extracts.
The authors performed some calculations, indicating that the e-liquids with the highest amounts of benzaldehyde and vanillin in the whole study would expose users to more than the recommended workplace exposure for those chemicals, although the average levels found in the study suggest that vapers’ exposure is lower than the workplace limits.
4 – Is the Nicotine Labeling on E-Liquids Accurate?
The researchers on this study gathered a sample of e-liquids from around the world – 32 from the U.S., 29 from South Korea and 30 from Poland – and analyzed the nicotine levels contained within them. The results showed that, despite much concern about unreliable nicotine levels in e-liquids, the vast majority of samples didn’t vary significantly from the amount indicated on their label. In the whole sample, 19 percent of all e-liquids had discrepancies of over 20 percent between their labeled and actual nicotine content. In the U.S. samples, the level of nicotine detected varied between 0 and 3.66 percent, but the researchers found that three products labeled as nicotine free did contain detectable traces of nicotine. Overall, it shows that while most e-liquids are labeled accurately, mixers should take extra care to ensure accurate nicotine content.
3 – Is E-Liquid Toxic to Cells?
This toxicological study looked at 20 different e-liquid samples, and set out to determine if the vapor produced from them was toxic to heart cells, and offered a comparison with cigarette smoke. The researchers found that cigarette smoke was toxic to cells at concentrations higher than 6.25 percent, but almost all e-liquids weren’t toxic at any concentration. However, four e-liquids were toxic to cells at the highest concentrations, and this suggests that the toxicity of e-liquid varies according to flavor, rather than nicotine concentration or the base ingredients (PG or VG) used (this was confirmed using a sample not containing flavors or nicotine). Overall, the authors conclude that all e-liquids are significantly less toxic to heart cells than cigarette smoke.
2 – Do Flavors Matter for Vapers?
With all the concern about flavors attracting children to vaping (despite the study already mentioned that found this not to be true), this study aimed to determine whether removing available flavors would impact on ordinary adult consumers. Over 4,600 vapers answered an online survey, looking at their smoking status and their views on flavored e-liquids, with particular consideration to their role in helping them quit smoking (as over 90 percent of the sample had).
The results showed that successful quitters switched flavors more than those still smoking, with almost 70 percent of them doing so daily or more. The respondents classed the variety of flavors available as “very important” for quitting smoking, and most said that restrictions on available flavors would make vaping less enjoyable. In addition, almost half said reducing the flavors on offer would increase their cravings for cigarettes, and just under 40 percent said they would have been less able to quit or reduce smoking without them. In short, the study showed that reducing the availability of flavors could drastically impact the potential of e-cigarettes to help smokers quit.
1 – How Many E-Liquids Contain Diacetyl?
One of the core issues for vaping is the potential for risks related to specific flavors, and diacetyl (a buttery flavor) is the poster-chemical for this danger, being associated with a rare condition impacting on lung functioning. This study took a sample of 159 e-liquids (from 36 manufacturers) and tested them for diacetyl and acetyl propionyl (a similar chemical that likely has similar risks), choosing liquids that potentially contained the chemical due to their flavor descriptions. The results showed that a huge 74.2 percent of samples contained either diacetyl or acetyl propionyl, sometimes despite assurances to the contrary. The median daily exposure for a vaper was calculated as being slightly lower than the recommended maximum workplace exposure, but almost half of diacetyl-containing and over two-fifths of acetyl propionyl-containing samples exceeded these limits. Calculated levels of diacetyl exposure from vaping were 100 times lower than smoking, and for acetyl propionyl it was 10 times lower than from smoking. Regardless, the authors identified these chemicals as a completely avoidable risk for vapers.
Conclusion – We Know a Lot, But We Need to Know More
Potentially the most important thing we need more information on is the risk associated with different flavoring chemicals, because the more we find out, the more responsible mixers can avoid sources of unnecessary risk. With diacetyl in particular, companies that openly publish results of lab testing of their e-liquids should be favored by vapers, because assurances of “no diacetyl” aren’t always reliable.
The available research might show some areas where we need more data, but it does go a long way to addressing some myths about vaping. It’s clear that claims of e-liquid flavors attracting non-smoking youths to vaping are not backed by available evidence, nor are concerns about e-liquid poisonings, as well as claims that e-cigarettes are just as addictive as cigarettes. If you’ve learned nothing else, it should be that it’s better to base your opinions on the science than over-hyped media reporting of the findings.
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