The effects of tobacco on health and reasons for avoiding its use
Tobacco is most commonly smoked in cigarettes but can be smoked in cigars and pipes, inhaled as snuff, or chewed. However it is used, tobacco is harmful to health. In the UK, smoking is one of the main causes of death in people under the age of 65, leading to about 106,000 deaths each year. It is known to be a major contributing factor to coronary heart disease and primary lung cancer. Smoking also damages the health of “passive smokers”, who inhale other people’s smoke from the air around them. The only way to avoid the risks associated with tobacco smoking is to avoid smoking and those situations in which you come into contact with other people’s smoke. Avoiding tobacco smoke became easier in the UK with the ban on smoking in workplaces and enclosed public spaces.
In the UK, the number of smokers has declined from about half the population in the early 1970s to less than 1 in 4 in 2008. The proportion of people who smoke is highest in the 20–24 age group and lowest in those aged 60 or over.
Tobacco smoke contains many substances that are toxic or irritating to the body. The substances that have been studied most extensively are tar, carbon monoxide, and nicotine. Tobacco smoke also contains carcinogenic (cancer-causing) substances that have toxic effects on the lungs and other organs.
Tar in tobacco smoke irritates and inflames the tissues of the lungs. Carbon monoxide attaches itself to red blood cells, reducing their capacity to carry oxygen. Nicotine acts as a tranquillizer, starting to take effect within 10 seconds of ingestion and producing a temporary feeling of wellbeing and relaxation. The substance is also known to increase the ability to concentrate. It stimulates the release of the hormone epinephrine (adrenaline) into the bloodstream, and this causes a rise in blood pressure. Nicotine is highly addictive, which is why most tobacco users find it hard to give up the habit. There are many damaging long-term effects of tobacco use, some of which are exacerbated by other aspects of a person’s lifestyle, such as drinking excessive amounts of alcohol.
Substances in cigarette smoke irritate the mucous membranes that line the air passages to the lungs, causing them to produce more mucus (sputum). These substances also paralyse the tiny hairs, called cilia, that help to expel sputum from the air passages. To clear their lungs, many smokers develop the characteristic “smoker’s cough”. Eventually, smoking may result in chronic obstructive pulmonary disease, which leads to severe shortness of breath.
Carcinogens in cigarette smoke cause over 8 in 10 of the deaths from lung cancer. In some countries, lung cancer has overtaken breast cancer as the leading cause of cancer-related deaths in women, a fact reflecting the large number of women who took up smoking during the second half of the 20th century. Smoking also causes cancer of the nasopharynx and cancer of the larynx. The risk of developing cancer of the larynx is even higher for cigar or pipe smokers and for people who both smoke and drink alcohol.
Smoking is known to cause permanent damage to the cardiovascular system and has been linked to a significant number of deaths from cardiovascular disease. This damage is thought to be caused by the nicotine and carbon monoxide present in cigarette smoke, which may encourage the development of atherosclerosis, a condition in which the arteries become narrowed. Atherosclerosis in turn is known to increase the risk of stroke and cardiovascular disorders such as coronary heart disease. In women over the age of 35, tobacco smoking increases the risk of developing disorders associated with the use of oral contraceptives, in particular deep vein thrombosis and stroke.
Smokers are at increased risk of developing mouth cancer and cancer of the oesophagus, particularly if they also drink alcohol. Carcinogenic chemicals from tobacco smoke that enter the bloodstream may also cause cancer in other parts of the body, such as the bladder (see Bladder tumours) and the cervix (see Cancer of the cervix).
The toxic effect of tobacco smoke may aggravate conditions such as peptic ulcers. Smoking may reduce fertility in men and women. If a pregnant woman smokes, her baby’s birth weight is likely to be about 200 g (7 oz) lower than the average, and the baby is at greater risk of illness or death just after birth. The menopause may occur earlier in women who smoke. Smoking also affects the skin and accelerates skin changes, such as wrinkling, caused by aging and sunlight.
People who smoke cigars or pipes run a higher risk of developing mouth cancer and throat cancers. Snuff and chewing tobacco may also irritate the lining of the nose, mouth, and stomach.
Inhaling the smoke from other people’s cigarettes is known as passive smoking. Secondhand smoke, also called environmental tobacco smoke (ETS), is a mixture of smoke from burning cigarettes and that exhaled by smokers.
ETS irritates the eyes, nose, and throat and may cause headaches and nausea. It may also worsen respiratory disorders such as asthma. The risk of developing lung cancer and heart disease is increased for nonsmokers who are exposed to ETS for long periods.
The children of smokers are particularly at risk from passive smoking. As babies, they are at increased risk of sudden infant death syndrome. Children of smokers are also more susceptible to asthma (see Asthma in children), and, if they have asthma, their attacks may be more severe and more frequent. They are also more prone to ear, nose, and respiratory infections, such as colds, sinusitis, acute bronchitis, and chronic secretory otitis media, a common cause of hearing impairment in children. The children of smokers are also more likely to smoke themselves when they get older, and, as adults, are at increased risk of developing chronic obstructive pulmonary disease and cancer.
You can prevent disease by not smoking or by giving up smoking before you begin to develop any smoking-related illness. However, no matter how long you have been smoking, you can prevent further damage to your health by quitting (see Health of ex-smokers). As soon as you stop smoking, you begin to reduce your risk of developing lung cancer and other respiratory disorders, cardiovascular disease, and stroke. You will also be less likely to suffer from a range of conditions that are associated with smoking, such as peptic ulcer. You are never too old to benefit from this reduction in risk; even elderly people who have been smoking for most of their adult lives can improve their health and life expectancy by stopping.
Some smokers find it relatively easy to quit but most find it difficult because they are addicted to nicotine. It is the physiological affects of this addiction that cause the craving that gradually builds up between cigarettes and the withdrawal symptoms – such as agitation, irritability, depressed mood, increased appetite, dizziness, and difficulty sleeping – that occur after a longer period without smoking.
Various forms of help are available to help smokers quit. Your doctor, practice nurse, or pharmacist can give information and advice on stopping smoking. There are also NHS “Stop Smoking Clinics”; home support services; and an NHS helpline. The NHS also has a “Smokefree” website that gives information about how to quit and the various services available.
Many smokers trying to quit find nicotine replacement therapy (NRT) helpful. This is available over the counter in various forms: chewing gum, patches, tablets, lozenges, inhalators, and sprays. All of these give you a dose of nicotine, which helps reduce the tobacco craving and other withdrawal symptoms. Some people also find complementary therapies, such as hypnotherapy and acupuncture, helpful.
Drugs such as bupropion (Zyban) and varenicline (Champix), used in conjunction with self-help measures, may also be helpful in quitting. However, these drugs are available only on prescription and are not suitable for everybody. Bupropion should not be used by women who are pregnant or breast-feeding, by those with a history of seizures or who are at increased risk of seizures, or those who have an eating disorder. It may cause various side effects, including dry mouth, gastrointestinal disturbances, and sleep problems. Varenicline should not be used during pregnancy. Possible side effects include gastrointestinal disturbances, dry mouth, headache, drowsiness, dizziness, sleep problems, depression, and suicidal thoughts.
As well as giving up smoking yourself, it is also important to teach children about the health risks of smoking because if they can be prevented from starting, they are more likely never to smoke.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.