14 December 2005

What is in tobacco smoke?

- There are more than 4,000 chemicals in tobacco smoke - nicotine, tar, carbon monoxide and other chemicals and additives.

- Nicotine is a chemical substance found in tobacco leaves. Addiction to nicotine is what keeps you smoking. Nicotine is as addictive as heroin or cocaine. From the moment that you inhale tobacco smoke, it takes four seconds for the nicotine to reach your blood stream and about ten seconds to reach the brain. Once the nicotine has attached itself to special sites in the brain, many relaxing chemicals are released. However, this effect only lasts for a short time and then the addicted smoker needs to ‘top up’ their nicotine. One of the reasons people continue to smoke is because they enjoy the effect of these relaxing chemicals being released by the brain.

The worst problem for health caused by nicotine is that it is so addictive. Most regular smokers would prefer not to smoke, and only continue because they are addicted to nicotine. Smoking tobacco accounts for the largest proportion of preventable illness and death. Immediate effects of nicotine on the body include increased heart rate and blood pressure and constriction of blood vessels. Over time, ingestion of nicotine from smoking combines with carbon monoxide to damage the lining of blood vessels and make blood platelets stickier. In combination, these effects contribute to the development of heart disease.

- Tar is the black, sticky substance that damages your lungs. The word ‘tar’ describes the particulate matter which, generated by burning tobacco, forms a component of cigarette smoke. Each particle is composed of a large variety of chemicals consisting mainly of nitrogen, oxygen, hydrogen, carbon dioxide, carbon monoxide, and a wide range of volatile compounds.

In condensed form, tar is a sticky brown substance that is the main cause of lung and throat cancer in smokers. Tar can also cause unsightly yellow-brown stains on fingers and teeth. Some tar is exhaled, some is coughed up, and some is absorbed by the lungs, which can cause lung cells to die. Cigarette smoke damages the ‘cilia’ (fine hairs that line the upper airways to protect against infection). When cilia are damaged, tar can penetrate further into the lungs. Tar coats your lungs like soot in a chimney and causes cancer. A 20-a-day smoker breathes in up to a full cup (210 g) of tar in a year.

- Carbon monoxide is a poisonous gas that competes with oxygen in the blood. This same gas is found in car exhaust fumes. Carbon monoxide binds to red blood cells, making it harder for the body to carry oxygen to the muscles and organs. In large quantities, carbon monoxide is rapidly fatal. Smokers can have up to 10 times the amount of carbon monoxide in their bloodstream than non-smokers. Heavy smokers may have the oxygen carrying ability of their blood cut by as much as 15%. Carbon monoxide robs your muscles, brain and body tissue of oxygen, making your whole body and especially your heart work harder. Smoking in pregnancy can lead to a dramatic reduction for oxygen available to the developing baby.

Some of the other chemicals and additives found in cigarettes (and some of their other uses) are: ammonia (household cleaning agent); acetone (nail polish remover); naphthalene (mothballs); methanol (rocket fuel); formaldehyde (which preserves the dead); phenol (disinfectant); hydrogen cyanide; metals (76 metals including arsenic, cadmium, nickel); radioactive compounds (polonium-210 and potassium-40); acetic acid (vinegar); toluene (industrial solvent); pesticides.

There are no standards or controls on what may be used in the growing and production of tobacco, including additives and agricultural chemicals. Herbicides, insecticides, fungicides, fertilizers and other agricultural chemicals are routinely used in tobacco growing. Additives are added to cigarettes in the manufacturing process to:
- add flavor, including sugar, honey, liquorice, cocoa, and chocolate liqueur to lessen the harshness of the smoke;
- lessen the irritating effects of smoke. Menthol and eugenol numb the throat;
- change the chemistry of nicotine. Ammonium salts and acetaldehyde (in burnt sugar) increase nicotine’s addictive potential;
- change the chemistry of smokers’ brains to make them more receptive to nicotine.

There are a number of problems with additives:
- Additives such as sugar and honey might seem harmless because we are used to eating them, but when additives in cigarettes are burnt, they can change into different chemicals, some of which are toxic. For example, liquorice and sugar produce cancer-causing chemicals when burnt. Also, these substances are inhaled into the lungs, which are delicate and much more vulnerable to harm than the stomach and intestines.
- The health effects of additives on smokers are not made public by the tobacco companies, and many may not be known at all.
- Some additives make tobacco smoke less harsh and taste better. It may make it easier for children to learn to smoke, and make smoking more agreeable to smokers.

There is no such thing as a ‘safer’ cigarette or ‘healthier’ tobacco. Changing to low-tar cigarettes does not help because smokers usually take deeper puffs and hold the smoke in for longer, dragging the tar deeper into their lungs. All tobacco smoke is damaging to health. The best way to prevent exposure to the chemicals in tobacco smoke is to avoid exposure to tobacco smoke.

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