After the Spanish discovery of America, tobacco smoking soon reached Europe. People were certainly smoking in Great Britain by the second half of the 16th century. This was not without resistance. In 1604, very soon after he came to the throne, King James I famously wrote A Counterblaste to Tobacco, in which he presciently described it as [a] “custome lothsome to the eye, hatefull to the Nose, harmefull to the braine, dangerous to the Lungs, and in the blacke stinking fume thereof, neerest resembling the horrible Stigian smoke of the pit that is bottomlesse”.
The product was promptly taxed, but smoking continued to be a popular social pursuit for over three centuries. Smoking is very addictive because of the nicotine in the tobacco. Although smoking tobacco destroys most of the nicotine that it contains, enough survives to be inhaled and transported via the lungs and blood to reach your brain within seconds. There it releases neurotransmitter molecules like dopamine, which causes pleasure sensations. The small time gap between smoking and the dopamine–fuelled sensation makes your brain associate pleasure with smoking, you are on the pathway to addiction.
From 1948 onwards, Richard Doll led the studies that showed the serious health effects of smoking. It kills around 6 million people a year worldwide, around 100 000 of those in the UK.
There are over 4 000 different compounds in cigarette smoke many being carcinogens like benzo[a]pyrene and nitrosamines such as N’-nitrosonornicotine (NNN), which is derived from nicotine. The ‘tar’ which finds its way to the mouth and lungs, is rich in these toxic substances. Cigarette smoke damages the DNA in organs, including some not directly exposed to it, and this can lead to cancers - in the lungs of course, but also the mouth, larynx, liver, cervix, oesophagus, pancreas, bladder and kidney. Nicotine does not cause cancer, but addiction to nicotine can lead to cancer.
E-cigarettes are marketed as a way to enjoy smoking with a much lower level of health risk than traditional smoking. They still often contain nicotine, but there’s more to it than just addiction. E-cigarettes do not burn tobacco, which eliminates the carcinogens found in tar. They contain a heating element, which vapourises substances found in the ‘e-liquid’, the vapour then being inhaled by the ‘vaper’. In addition to nicotine, this liquid contains a solvent, either glycerol or propylene glycol (or a mixture of the two), nicotine, and often food-grade flavourings. A number of the flavouring molecules belong to the aldehyde family, while they are safe to be consumed in foods (examples being vanillin (vanilla) and cinnamaldehyde (cinnamon)) their hot vapours irritate the mucosal respiratory tract when you inhale them. Recent research has shown that aldehydes can react with alcohols, including those used as solvents, to form a class of compound known as acetals, which are more irritating than the parent aldehydes. Menthol is another common flavouring, which is known to increase absorption of nicotine.
A number of e-cigarette flavourings have been tested upon endiothelial cells , which line blood vessels and the inside of the heart; they cause damage affording higher levels of the inflammatory marker interleukin-6 and lower levels of nitric oxide, which has several roles in the body, including inhibiting inflammation and clotting, and dilating blood vessels. These two changes are considered to be an early predictor of heart disease.
There are problems with the solvents. At normal temperatures, they are quite safe, but when heated to 300 °C they decompose forming a number of products including acrolein, methanal and ethanal. All are toxic. Methanal is a carcinogen, whilst acrolein causes irritation to eyes and nasal passages.
Nevertheless, risks associated with vaping have been perceived to be low, compared to smoking, until a wave of reports from the USA from July 2019 onwards. Well over 1500 healthy people have developed serious lung injuries, serious enough to mean they have to be hospitalised, and numbers (35 at October 22nd) have died. The vaping scene in the USA is different to that in the UK, with many more people using vaping as a way of delivering THC (the active ingredient in cannabis). There also seems to be a much bigger illicit market for unapproved vaping materials.
No one knows what is causing these problems. One possibility is vitamin E acetate, which is sometimes added to the vaping liquid to thicken it and make it appear that the product is more potent than it actually is.
Others think that some of the flavouring agents added to the e-liquid are to blame, with sweet or fruity flavours being designed to appeal to the teen market and to get them hooked.
The American CDC (Centers for Disease Control and Prevention) recommend that people do not use e-cigarette, or vaping, products that contain THC, or buy any sort of vaping products ‘off the street’. Moreover, they say, youths, young adults, or pregnant women should not use e-cigarette or vaping products.
In the UK, Dame Sally Davies, the Government’s Chief Medical Officer for nearly a decade, has said that she too would favour a ban on flavoured e-liquids.
Latest reports from the USA indicate most fatalities occurred among people using THC-containing products, as a possible reason for the differences between the situation in the USA and the UK. There appears to be a different issue here to attempts to get young people addicted to nictotine through flavoured e-cigarettes.