Have you ever heard of cytotoxicity? Well, if you are like most people that is not a word you use every day of the week. Cytotoxicity refers to how toxic a substance is. It is the measure of a substances potential to kill or damage a cell. There are some substances that have a very high cytotoxicity, tobacco cigarette smoke is among these. This means that tobacco smoke kills cells at a very high rate. This does not come as a surprise to most people. There has been a lot of research done on the subject. But what about the cytotoxicity of electronic cigarettes?
Many people say that electronic cigarettes are healthier then tobacco cigarettes. If this is true then e-liquids would have a much lower incidence of cytotoxicity than tobacco smoke. Up until this point, there has been very little research conducted on the safety of electronic cigarette vapour, to determine its relative cytotoxicity. For this reason, Dr. Konstantinos Farsalinos and a team of researchers decided to test various electronic cigarette vapours to determine their relative cytotoxicity. In their study, twenty e-liquids were tested against the results of tobacco cigarette smoke.
Tobacco cigarette smoke is known to have a high cytotoxicity, in part because of the thousands of chemicals in it. A lot of these chemicals are produced when tobacco is burned. Since electronic cigarettes don’t contain tobacco, this chemical reaction that produces most of these chemicals, is not present in them. Because of this, it was theorized that electronic cigarette vapour would show a much lower level of cytotoxicity then tobacco cigarette smoke shows.
Let’s look at how the study was conducted. Twenty e-liquids were used in this study; all taken from varying distributors. Each e-liquid was tested on cultured heart cells, to determine the effect of the liquid on the cells. The testing was done in vitro, meaning in a lab, on cultured heart cells. For many reasons, it is not possible to do this testing in vivo, meaning in live subjects. To get the most accurate results, tobacco smoke was also used on cultured heart cells to determine its effect on the cells. These in vitro results from the tobacco smoke could be looked at in light of already collected evidence from in vivo data. This would help the researcher to understand how their findings, from a controlled lab environment, translated into real life applications.
All e-liquids were converted to a vapour before being tested on the heart cells. All electronic cigarettes were activated at 6.2 Watts, and then four random samples were also activated at 9.2 Watts. This study was the first to look how the use of high voltage effects e-liquid toxicity. To help keep the consistency in testing, all batteries were fully charged before each use and atomizers where replaced before each test. An experienced vaper also tested the e-cigs for what is called dry-puffs. This is when there is not enough liquid in a wick. The length of each puff was then corrected, if need, to account for this aspect of vaping.
Both the vapour and smoke from the tobacco cigarettes were tested on the cultured heart cells. A control group of cultured heart cells, which did not have either vapour or smoke exposure, was also studied. This allowed for rate of cell death ratios to be taken for each substance along with the control group. If more the 30 percent of the cell is killed, the substance considered to be cytotoxic.
As put forth in their theory, overall the e-liquid exhibited a much lower cytotoxicity than the tobacco smoke. The results were looked at in relation to the viability of each substance. Viability is the term that is used to describe the amount of cells that are able to live through the experiment. The lower the viability percentage the low the amount of living cells. The higher the viability percentage, the higher the amount of living cells. Not surprisingly, cigarette smoke at a concentration of over 12.5 percent always produced cytotoxicity. The pure extract produced a viability of 3.9 percent.
When testing the e-liquids, varying degrees of concentrations were tested. Extracts in pure form were also tested. Only four e-liquids reached cytotoxicity. One was the Cinnamon Cookie e-liquid which had a viability of around 65 percent. The other three were pure extracts that were produced by the House of Liquid and used actual tobacco leaves in the making of the e-liquid flavouring. The rest of the e-liquids had no cytotoxicity and a much higher viability.
There were then four samples that were tested randomly at high voltages. None of these showed cytotoxicity. Although their viability did drop slightly. This indicates that there can be a minimal health risk if using higher voltages. But none of these were effected enough to cause them to become cytotoxic. They also tested differing nicotine levels for cytotoxicity. The different levels did not cause any cytotoxicity, although there was a slight drop in viability depending on how pure the extract was. The Propylene glycol and vegetable glycerine never produced cytotoxicity or any noticeable drop in viability.
After analysing all the results, it is clear that according to this study the main thing that impacts the cytotoxicity of e-liquids in what is used to flavour the e-liquid. It is interesting to note that one of the e-liquids from the House of Liquid was even worse than the pure extract of tobacco cigarette smoke in regards to viability. While another e-liquid that was produced using the same technic was not cytotoxic at all. It is possible that impurities were able to seep through during the manufacturing process and possibly the use of different leaves also had an impact on the final products toxicity. More research is needed to understand the implications of this finding in regards to the use of actual tobacco leaves in the manufacturing of a flavour. Fortunately, this is not a common practice for most manufacturers.
Overall this research showed very positive results. Although there was a small risk associated with some e-liquids, this was related to the flavouring added or how that flavouring was manufactured. The nicotine, propylene glycol and vegetable glycerine, which are the main ingredients in e-liquids, did not cause any cytotoxicity as pointed out in the results. The worst results, from the e-liquid samples, came from an unusual manufacturing process and need more research to understand and help this procedure to be safer. The other e-liquid that showed slight cytotoxicity was the e-liquid which used cinnamon oil in the flavouring. This is understandable due to the known potential toxicity of cinnamon oil. It was noted that the other flavouring did not carry any risk of toxicity.
In conclusion, this research indicates that e-liquids, on a whole, do not produce the type of destruction and death to cells that tobacco cigarette smoke produces. There were minor risks associated with the use of cinnamon flavouring and the House of Liquids’ tobacco flavouring. This needs to be researched more to help make the process healthier. At this point, it might be safer to avoid such flavours. Overall the e-liquids did not show cytotoxicity. This research indicates that e-liquids are a much healthier option than tobacco smoke, due to the fact that they are much less likely to kill cells.