What is toxicity?
- The level of toxicity relates to how much damage a substance can do to an organism.
What is cytotoxicity?
- Cytotoxicity refers to how damaging cigarette smoke and ecigarette vapour (in this case) can be to heart (myocardial) cells.
Is there something special about heart cells?
- Yes, they are very special. Individual hearts cells pulse and, as part of the heart organ, contract in together to provide a pump to get the blood around the body.
So, if they are damaged they don’t get replaced?
- Initially it was thought that the heart cells do not get replaced throughout your lifetime but recent evidence suggests that some do although by death less than half of the heart’s cells will have been replaced.
That doesn’t sound good?
- If you damage a single cell it will cease to function. If a group of cells are damaged the heart stops pumping efficiently and can lead to a myocardial infarction – a heart attack.
So, did they blow smoke and vapour directly onto a beating heart?
- No, it would be difficult to find a patient willing to be opened up.
How is the experiment carried out then?
- Heart cells are grown in a laboratory for the purpose of being experimented upon.
Is there a fancy term for this?
- The phrase used is in vitro (in a test tube).
What was known before they started?
- There is a lot of information about the cytotoxic effects of tobacco smoke.
- Smoke has in the region of 10,000,000,000,000,000 free radicals in each puff.
What is a free radical?
- A free radical is an atom or group of atoms with an unbalanced number of electrons.
What do they do?
- Free radicals are associated with the ageing process and the toxic effect on heart cells.
How was the experiment designed?
- It used 20 different eliquids and a “control” which consisted of a 50/50 PGVG mix without any nicotine or flavouring.
- Four of the liquids were made using a tobacco leaf steeping process, these were provided by House of Liquid.
- The liquids were bought from shops.
- They ranged from 6mg to 24mg in strength.
- The flavours chosen were selected using an online poll of the most popular.
- To avoid the possibility of dry-burns one member of the team (a vaper) tested each device prior to use to ensure the wick was primed.
- The experiment used a standard procedure for testing for toxicity
- After exposure the cells were measured after a 24-hour incubation period.
- Marlboro cigarettes were used for the smoke experiments.
So, what were the results?
- “Cinnamon Cookies” flavour was slightly cytotoxic in its highest concentration.
- “Cigarillos” and “Puros” were cytotoxic at 50% and 100% concentrations.
- The base consisting of just VG/PG was not cytotoxic at all.
And the conclusions?
- The team concluded that just four from the twenty were cytotoxic.
- Of those, three were from the samples involving the tobacco leaf steeping process.
- There is the possibility that tobacco leaf particulates could have contaminated the test.
- “Guevara” demonstrated no cytotoxic effects.
- “Cinnamon” just hit the cytotoxic levels. The main flavouring, cinnamaldehyde, breaks down at high temperatures and forms benzaldehyde that may be causing the results.
- Using higher voltages also impacted upon the survival rate of cells, a point of importance to sub-ohmers.
That doesn’t sound great; didn’t Dr Farsalinos say something positive?
- Yes, the team finished by stating that e-liquid vapour is orders of magnitude safer than tobacco smoke.