What is in a cigarette?

Cigarettes appear to be very simple products - paper tubes filled with tobacco. But, in fact, cigarettes are highly sophisticated packages, engineered to deliver doses of the addictive drug nicotine.

A huge number of additives and flavourings are added to cigarettes to make nicotine more attractive and palatable. The European Union has a list of over 600 additives that manufacturers may use in the creation of their cigarettes.1 And, when smoked, cigarettes release over 4,000 chemicals, a number of which are carcinogenic (cancer causing).2

Cigarette companies have spent decades perfecting their product, which is why people find it so hard to give them up. Many of the additives, such as chocolate, sound innocent. But their purpose is to keep smokers smoking by making the experience as pleasurable as possible. Ingredients are also added to mask the smell and even visibility of 'side-stream' smoke from the burning tip of the cigarette, to minimise discomfort to non-smokers.3,4,5 Unfortunately, these ingredients make it harder for non-smokers to see, and therefore avoid, other people's smoke.

Below is a list of just some of the more interesting ingredients you can find in a normal cigarette.

Nicotine
Carbon monoxide
Tar
Hydrogen cyanide
Ammonia
Sugar
Organic acid salts
Cocca
Pyridine
Chocolate and honey
Menthol
Liquorice
Fillers
Paper
Filters

Nicotine

Nicotine from tobacco leaves is the main addictive ingredient in cigarettes. It is delivered into smokers' lungs in a potent mixture of smoke particles and gases. The nicotine is rapidly absorbed into the blood and reaches the brain within about 10 seconds. At this point the smokers experiences a nicotine "hit" or "kick" - this is when the receptors in the brain produce chemicals called dopamines. The brain soon comes to expect regular doses (or "hits") of nicotine and suffers withdrawal symptoms when the supply is interrupted.

Nicotine stimulates the central nervous system, increasing the heart beat rate and blood pressure. This results in the heart needing more oxygen.

Carbon monoxide

All cigarette smoke contains carbon monoxide - the same poisonous gas given off by car exhausts and faulty gas fires. Carbon monoxide prevents the blood from carrying oxygen round the body by binding itself to the blood's haemoglobin. In heavy smokers, their blood's capacity to carry oxygen is reduced by as much as 15 percent.6

Tar

"Tar" is the collective term for the thousands of chemicals that are released in cigarette smoke. Tar is the sticky yellow-brown substance which stains smokers' teeth and fingers. It is deposited in the lungs every time a smoker draws on a cigarette. Smoking 20 to 60 low to high tar cigarettes a day will coat your lungs in 1 to 1.5 pounds of tar every year.7 Tar is responsible for most of the damage to the health of your lungs.

Hydrogen cyanide

Visible smoke accounts for only 5-8 percent of the output of a burning cigarette. The rest is made of invisible gases - including hydrogen cyanide.7 This poisonous gas reduces the body's ability to transport oxygen. Other invisible gases, such as nitrosamines, damage the body's cells and can trigger cancer tumours. Cigarette smoke also contains chemicals that can produce gene mutations that have been linked to lung cancer.

Ammonia

Adding ammonia to a cigarette means that the smoker "freebases" the nicotine - in much the same way as a crack user takes cocaine. Ammonia speeds up the delivery of so-called "free" nicotine by raising the pH (alkalinity) of tobacco smoke. Raising the pH of smoke changes the chemical form of nicotine so that it is more rapidly absorbed by the body. The result is a much stronger nicotine hit.8

Sugar

The most common tobacco additives are sugars of various kinds.9 Sugar makes up about 3 percent of the total weight of a cigarette.10 When a cigarette is lit, the sugars begin to burn and produce a chemical called acetaldehyde.11 Acetaldehyde enhances the addictive effect of nicotine.12

Organic acid salts

Nicotine on its own produces smoke that is harsh and irritating. Adding organic acid salts masks the harshness of the smoke and produces a smoother taste. In addition, organic acid salts (such as levulinic acid) also make the brain more receptive to nicotine.13

Cocoa

Cocoa contains a chemical called theobromine, which encourages the airways to expand.14 This "bronchodilator effect" makes it easier for the smoker to breathe deeply. So they take in greater amounts of smoke and nicotine. Cocoa butter may also be added: it is believed to reduce the harshness of smoke and create a smoother smoking experience.15

Pyridine

Pyridine acts as a depressant on the central nervous system. It works with nicotine to boost the effect of smoking.16

Chocolate and honey

Flavourings such as chocolate17 and honey help disguise the bitterness of nicotine. The sweet taste makes cigarettes more palatable.

Menthol

Without additives tobacco smoke not only tastes bad, it is also extremely irritating to the throat. Menthol numbs the throat so the smoker cannot feel the abrasive effect of the smoke. In this way the body's natural reaction to an irritant can be overcome.

Liquorice

Liquorice is one of the most effective flavourings in cigarettes.18 According to the British Association of Tobacco Manufacturers (BAT) it produces a"mellow sweet woody note".18 This "greatly enhances the quality of the final product." "Quality" flavourings play a vital role in masking the bad taste of low quality tobacco. Glycyrrhizin - an ingredient of liquorice - also expands the airways, helping the smoker to breathe in more smoke.19

Fillers

Cigarettes contain chopped up tobacco leaf. But extra bulk is created by adding 'fillers' made from the tobacco stems and other bits of waste product.20 Fillers are mixed with water, flavourings and other additives. Some brands have more fillers than others. A high filler content makes a cigarette less dense. The amount of nicotine delivered may be slightly reduced.

Paper

The type of paper used in the tube wrapping of a cigarette can effect its strength. More porous paper lets more air into the cigarette, diluting the smoke. This may reduce the amount of tar and nicotine that is inhaled.20

Filters

Filters, made of cellulose acetate, trap some of the tar and smoke before they can reach the smoker's lungs. They also cool smoke and make it easier to inhale. Filtered "low tar" cigarettes (with ventilation holes in the sides of the filters) were developed by the tobacco industry in response to health concerns. But evidence suggests that "low tar" cigarettes do not result in smokers inhaling lower doses of nicotine.21,22,23 It appears that smokers compensate for the diluted effect of these cigarettes by inhaling more deeply or frequently. Smokers can also block the ventilation holes in the filters with their fingers to increase the nicotine being inhaled. This is something they may do subconciously.

References:

1.   Department of Health. London. March 2000R.
2.   BAT December 12th, 1986, Mutagenic Activity of Flavour Compounds. FN AQ2222, BN 400916808-400916815
3.   BAT, Casings and Flavourings,BN401375070, FN EQ 2295
4.   BAT 1987, June 15th. Studies into alternative burn additives that reduce visible sidestream. FN AW 1428,
      BN 402385586-402385589.
5.   BAT September 9th, 1983, The addition of sugar solutions of Ca(oh)2 in sugar to cigarette paper.
      BN 100480228-0229 FN J562
6.   Royal College of Physicians. Smoking or Health. London, Pitman, 1977
7.   Henningfield, Jack E. Verbal Testimony. Jan 30 1997
8.   Santa Fe natural tobacco Co, 1994
9.   Tobacco additives. Cigarette engineering and nicotine addiction. C Bates, M Jarvis, G Connolly. 14 July 1999.
10. DeNoble V.J. Verbal Testimony 1/3/97 p77
11. Philip Morris 1982, Evaluation of the DeNoble nicotine acetaldehyde Data, Tobacco Resolution, BN 2056144727-4728
12. RJR 1989, Lippiello PM, Fernandes KG. "Enhancement of nicotine binding to nicotinic receptors by nicotine
      levulinate and levulinic acid." September 25 1989.BN508295794
13. Philip Morris, Bates number 2060535086
14. BAT October 1967, Cocoa Butter As A Tobacco Additive. BN 105534584, FN B4263
15. BAT, The absorption and mechanism of action of pyridine and its interaction with nicotine, FN AW2730,
      BN 402419398-9486
16. Tobacco Reporter, September 1979
17. BAT, Tobacco Flavouring For Smoking Products, BN104805407, FN F1500
18. Farone WA, Verbal testimony, Public hearing on proposed regulation: Reports on added constituents and nicotine ratings, 19. Massachusetts tobacco control program, June 12th 1997
20. Action on Smoking and Health. FACT SHEET NO. 12. August 2001. Benowitz NL, Hall SM, Herning, RI et al.
      Smokers of low-yield cigarettes do not consume less nicotine. New England Journal of Medicine, 1983; 309: 139-42.
21. Bates C., Jarvis M., Letter Tobacco Control 1999;8:106-112
22. Bates C., Jarvis M. Low Tar: why low tar cigarettes don't work and how the tobacco industry fooled the smoking public.
     1999 Edition. March 1999.