Cancer-causing chemicals in tobacco smoke Tar - a mixture of dangerous chemicals Tar Arsenic - used in wood preservatives Arsenic Benzene - an industrial solvent, refined from crude oil Benzene Cadmium - used in batteries Cadmium Formaldehyde - used in mortuaries and paint manufacturing Formaldehyde Polonium a highly radioactive element Polonium-210 Chromium - used to manufacture dye, paints and alloys Chromium 1,3-Butadiene - used in rubber manufacturing 1,3-Butadiene Polycyclic aromatic hydrocarbons - a group of dangerous DNA- damaging chemicals Polycyclic aromatic hydrocarbons Nitrosamines - another group of DNA-damaging chemicals Nitrosamines Acrolein - formerly used as a chemical weapon Acrolein
Other poisons in cigarette smoke Hydrogen cyanide - used as an industrial pesticide Hydrogen cyanide Carbon monoxide - found in car exhausts and used in chemicals manufacturing Carbon monoxide Nitrogen oxides - a major component of smog Nitrogen oxides Ammonia - used to make fertilisers and explosives Ammonia
Tar Tar is a term that describes a collection of solid particles that smokers inhale when they light a cigarette. It is a mixture of lots of chemicals, many of which can cause cancer. When it settles, tar forms a sticky, brown residue that can stain smokers teeth, fingers and lungs. Because tar is listed on packs, it is easy to believe that it is the only harmful part of cigarettes. But some of the most dangerous chemicals in tobacco smoke are present as gases, and do not count as part of tar. This means that cigarettes with less tar still contain all the other toxic chemicals.cigarettes with less tar
Arsenic Arsenic is one of the most dangerous chemicals in cigarettes. It can cause cancer as well as damaging the heart and its blood vessels. Small amounts of arsenic can accumulate in smokers bodies and build up to higher concentrations over months and years. As well as any direct effects, it can worsen the effect of other chemicals by interfering with our ability to repair our DNA.repair our DNA Fish and seafood can be major sources of arsenic, but in a form that is less toxic and more readily removed from the body. In contrast, tobacco smoke contains arsenic in a more dangerous form.
Benzene Benzene is a solvent used to manufacture other chemicals, including petrol. It is well-established that benzene can cause cancer, particularly leukaemia. It could account for between a tenth and a half of the deaths from leukaemia caused by smoking. Tobacco smoke contains large amounts of benzene and accounts for a big proportion of our exposure to this poison. The average smoker inhales about ten times more benzene than the average non-smoker. And some studies have estimated that the amount of benzene that a person inhales through second-hand smoke over their lifetime could increase their risk of cancer.
Cadmium Cadmium is a metal used mostly to make batteries. The majority of cadmium in our bodies comes from exposure to tobacco smoke. Smokers can have twice as much cadmium in their blood as non-smokers. Studies have found that the amounts of cadmium present in tobacco smoke are capable of affecting our health. It is a known cause of cancer, and can also damage the kidneys and the linings of the arteries. Our bodies have proteins that mop up harmful chemicals like cadmium, but the amounts in smoke can overload these proteins. Cadmium can also prevent our cells from repairing damaged DNA. Because of this, it can make the effects of other chemicals even worse.damaged DNA
Formaldehyde Formaldehyde is a smelly chemical used to kill bacteria, preserve dead bodies and manufacture other chemicals. It is one of the substances in tobacco smoke most likely to cause diseases in our lungs and airways. Formaldehyde is also a known cause of cancer. It is believed that even the small amounts in second-hand smoke could increase our lifetime risk of cancer.second-hand smoke Tobacco smoke is one of our major sources of formaldehyde exposure. Places where people smoke can have three times the normal levels of this poison.
Polonium Polonium is a rare, radioactive element and polonium-210 is its most common form. Polonium strongly emits a very damaging type of radiation called alpha-radiation that can usually be blocked by thin layers of skin. But tobacco smoke contains traces of polonium, which become deposited inside their airways and deliver radiation directly to surrounding cells. The lungs of smokers can be exposed to four times more polonium than those of non-smokers and specific parts may get a hundred times more radiation. One study estimated that someone smoking one and half packs a day receives the equivalent amount of radiation as someone having 300 chest X-rays a year.
Chromium Chromium is a metal used to make metallic alloys, dyes and paints and comes in different types. Chromium III or trivalent chromium is most commonly used. It is available as dietary supplements and is harmless. On the other hand, chromium VI or hexavalent chromium is very toxic, is found in tobacco smoke, and is known to cause lung cancer. It allows other cancer-causing chemicals (such as polycyclic aromatic hydrocarbons) to stick more strongly to DNA and damage it.damage it.
1,3 butadiene 1,3-butadiene or BDE is an industrial chemical used in rubber manufacture. Some scientists believe that of all the chemicals in tobacco smoke, BDE may present the greatest overall cancer risk. It may not be as good at causing cancer as some of the other chemicals listed here, but it is found in large amounts in tobacco smoke.
Polycyclic Aromatic Polycyclic aromatic hydrocarbons or PAHs are a group of powerful cancer-causing chemicals that can damage DNA and set cells down the road to becoming tumours.damage DNA One of these chemicals - benzo(a)pyrene or BAP - is one of the most widely studied of all tobacco poisons. BAP directly damages p53, a gene that normally protects our bodies against cancer.
Nitrosamines Nitrosamines are a group of chemicals that can directly damage DNA, like polycyclic aromatic hydrocarbons (PAHs).damage DNA They are found in small amounts in food. But tobacco products, including those that are chewed rather than smoked, are by far our largest source of exposure to these chemicals. Even though they are found in relatively small amounts in cigarettes, they are very strong cancer-causing chemicals.
Acrolein Acrolein is a gas with an intensely irritating smell and is one of the most abundant chemicals in cigarette smoke. It belongs to the same group of chemicals as formaldehyde and acetaldehyde, both of which can cause cancer. Until now, it wasnt clear if acrolein causes cancer as well, but recent experiments suggest that it can. We now know that acrolein can cause DNA damage that is similar to the damage seen in lung cancer patients. Since smoke contains up to 1,000 times more acrolein than other DNA-damaging chemicals, it could be a major cause of lung cancer. Acrolein also stops our cells from repairing DNA damage, like arsenic and cadmium. And like hydrogen cyanide, it kills the hairs that normally clean our lungs of other toxins.
Other chemicals Some of the other cancer-causing ingredients of tobacco smoke include: metals, such as nickel, lead, cobalt and beryllium. While you may be exposed to some of these metals through domestic items or food, inhaling them in tobacco smoke is worse, because they are easily absorbed by the lungs. acetaldehyde, which is also formed in your tissues when you drink alcohol - it is responsible for many nasty hangover symptomsalcohol hydrazine, a very toxic chemical used mainly in rocket fuel
Hydrogen Cyanide Hydrogen cyanide is a poisonous gas. Of all the chemicals in tobacco smoke, it does the most damage to the heart and blood vessels. Hydrogen cyanide does not cause cancer, but it increases the risk of other chemicals causing cancer by damaging cilia. These are tiny hairs lining the airways that help to clear toxins away. By killing cilia, hydrogen cyanide causes other dangerous chemicals to be stuck in the lungs and airways.
Carbon monoxide Carbon monoxide is a colourless gas with no smell. It is formed when we burn carbon-based fuels, such as gas in cookers or petrol in car engines. It can make up as much as 3-5% of tobacco smoke. Carbon monoxide sticks to our red blood cells in place of oxygen. This lowers our bloods ability to transport oxygen and deprives our tissues and organs of this vital gas. Like hydrogen cyanide, it kills cilia and reduces our lungs ability to clear away toxins. This means that while carbon monoxide does not cause cancer directly, it makes it easier for other chemicals to do so.
Nitrogen Oxide Nitrogen oxide is a gas found in car exhaust and tobacco smoke. Our bodies use it in very small amounts to carry signals between cells. But in large amounts, it is a major air pollutant. It directly damages lung tissue and causes inflammation in the lungs. Normally, our bodies produce small amounts of nitrogen oxide, which causes our airways to expand. The large amount of nitrogen oxide in tobacco smoke changes things in two ways: When smokers are smoking, it expands their airways even further, making it easier for their lungs to absorb nicotine and other chemicals. When they are not smoking, it shuts off their internal nitrogen oxide production line, causing their airways to constrict. This is one reason why regular smokers often have difficulty breathing.
Ammonia Ammonia is a gas with a strong, irritating smell, and is used in some toilet cleaners. Some studies have found that ammonia enhances the addictive power of nicotine. It changes nicotine into a gas that is more readily absorbed into the lungs, airways and bloodstream. Like carbon monoxide and hydrogen cyanide, ammonia also kills cilia.
More poisons Tobacco smoke also contains many other poisons that produce harmful effects. These can be carried throughout the body via our blood vessels. As well as hydrogen cyanide and ammonia, gases like sulphur dioxide also kill cilia (protective hairs) in our lungs. This stops them from being able to clear away other harmful chemicals. Chemicals like hydrogen sulphide and pyridine irritate our airways. Toluene can damage brain cells and interfere with their development.
Chemicals in cigarette smoke affect the entire body. This is why smoking causes so many diseases, including a dozen types of cancer, heart disease and various lung diseases. The diagram on the right shows just some of the types of cancer that are caused by smoking. As soon as you take a puff on a cigarette or breathe in someone elses smoke, poisonous gases like formaldehyde will start to irritate your eyes, nose and throat.formaldehyde
Your lungs and airways When you inhale the smoke, it damages the tissues of your airways and lungs. Chemicals like nitrogen oxide can constrict your airways, forcing your lungs to do more work and making breathing more difficult.nitrogen oxide Hydrogen cyanide, carbon monoxide and ammonia weaken the natural cleaning mechanisms that clear your lungs and airways of toxins. This means that other dangerous chemicals, bacteria and viruses that you inhale stay inside your lungs. Hydrogen cyanidecarbon monoxideammonia Radioactive polonium-210 becomes deposited at the points where your airways split to connect to your lungs. This can subject local cells to much more radiation than they would otherwise experience.polonium-210 From the lungs, cancer-causing chemicals and other poisons in tobacco smoke are absorbed into your bloodstream. These poisons are then carried to other parts of your body.
Your heart and blood vessels Many tobacco poisons such as arsenic and hydrogen cyanide can directly damage the cells that line your heart and its blood vessels.arsenichydrogen cyanide Nicotine and carbon monoxide cause blood vessels to constrict. Smoke also increases your level of blood cholesterol and as a result, raises your chances of developing a blood clot. Nicotinecarbon monoxide Gases such as carbon monoxide and nitrogen oxide reduce your bloods ability to transport oxygen. This lowers the amount of oxygen reaching your brain and other organs and reduces your energy levels.carbon monoxidenitrogen oxide
Smoking and cancer: Why do people smoke? People smoke for many different reasons. Smoking is very addictive because tobacco contains a powerful drug called nicotine. Smokers have also been influenced by the clever marketing tactics of tobacco companies for many years.
Nicotine as a drug Cigarettes are deliberately designed to give you a fast nicotine hit. It takes just 10 seconds for the drug to reach your brain from inhaled cigarette smoke. Nicotine causes addiction in much the same way as heroin or cocaine. It is just as addictive as these harder drugs. Nicotine is a stimulant that increases your heart rate and affects many different parts of your brain and body. Smokers get a high because nicotine triggers the release of dopamine in the brain - a chemical linked to feelings of pleasure. This also means that smokers start to make a mental link between the act of smoking and feeling good. Because of this, smokers can also become addicted to abstract things like the taste of cigarettes or the feeling of smoking, as well as the nicotine itself.
Withdrawal symptoms Addiction explains why giving up smoking can cause nicotine withdrawal symptoms. These symptoms include cravings, irritability, anxiety, difficulty concentrating, restlessness and disturbed sleep. As your body adjusts to the lack of nicotine, these symptoms will start to disappear and most will go away within a month. Withdrawal symptoms can be difficult to cope but the benefits to your health are well worth it.benefits to your health
Nicotine as a poison Nicotine is a neurotoxin (a poison that kills nerve cells) found in tobacco plants. It acts as a defence mechanism to stop them from being eaten by animals. However, in cigarettes, the level of nicotine is too low to cause poisoning. And the nicotine in nicotine replacement therapy (NRT) is a safe way to come off the nicotine in cigarettes. Using NRT can double your chances of successfully quitting. nicotine replacement therapy (NRT)
Tobacco advertising and promotion Half of smokers die from smoking-related diseases. The tobacco industry needs new customers to replace the 114,000 people who are killed by smoking in the UK each year. Cigarette manufacturers make sure that: they know exactly why people smoke they cleverly market products to attract new customers. In the past cigarette manufacturers have deliberately targeted children and young people. The industry spends a great deal of money on making cigarettes seem glamorous, appealing, fashionable and attractive. Most smokers started when they were young and image conscious. Young smokers often find it difficult to give up in later life. Cigarette advertising is now banned in the UK. So the industry is developing new and subtle tactics to avoid prosecution.
Stress and relaxation Many people claim that smoking helps them to cope with stress. But in fact, nicotine is a stimulant and wont help you to relax. Smokers probably think a cigarette makes them feel better because when they arent smoking they suffer from nicotine withdrawal.
Other personal reasons for smoking People have many other personal reasons for smoking. Smokers may: use smoking as a support for when things go wrong enjoy smoking with others as a shared activity use smoking to start conversations and meet new people smoke to make themselves look more confident and in control think that cigarettes help them to keep their weight down have a cigarette when theyre feeling bored or lonely smoke when they need a break or a moment to themselves.
Smoking and cancer: Children and smoking By the age of 15, around one in eight children have become regular smokers. Our own research has shown that trying just one cigarette can make children more likely to start smoking several years later.trying just one cigarette Children who smoke often become regular adult smokers. They also suffer immediate health consequences from smoking. Child smokers are more susceptible to coughs, increased phlegm, wheeziness and shortness of breath, and take more time off school. It is illegal to sell tobacco products to anyone under 18.
Why do children smoke? There are a number of reasons why children may try smoking.
Tobacco advertising Research has shown that advertising may encourage children to start smoking. Even adverts aimed at over 18s are attractive to children who aspire to adult behaviour. Direct cigarette advertising is now banned in the UK. Find out more about the Tobacco Advertising and Promotion Act in the public policy tobacco control section.public policy tobacco control
A sibling or parent who smokes Siblings and parents are role models for children. If a childs parents smoke they are three times more likely to smoke themselves.
Experimentation All teenagers experiment - often with activities that they believe make them appear more 'grown up'. Trying new things and making mistakes is part of the normal learning process. But the danger with trying smoking is that nicotine is very addictive.
Smoking and cancer: Second-hand smoke Breathing in other people's smoke can cause cancer. Second-hand smoke can increase a non-smoker's risk of getting lung cancer by a quarter, and may also increase the risk of cancers of the larynx (voice box) and pharynx (upper throat). Second-hand smoke can cause other health problems too, including heart disease, stroke and breathing problems. Even 30 minutes of exposure to second- hand smoke can reduce blood flow in a non-smokers heart. Every year, second-hand smoke kills about 11,000 people in the UK from lung cancer, heart disease and strokes.
Second-hand smoke and children Second-hand smoke is particularly dangerous for children because their bodies are still developing. Smoking when you are with your children can increase their risk of cot death, glue ear, respiratory illnesses such as asthma and chest infections, and possibly cancer later on in life. A study by the Royal College of Physicians showed that about 17,000 children in the UK are admitted to hospital every year because of illnesses caused by second-hand smoke. Over forty percent of children in the UK live in a household where at least one person smokes. If you are a smoker, try not to expose your child to your smoke.
The chemicals in second-hand smoke There are two types of tobacco smoke: mainstream smoke, which is directly inhaled through the mouth end of the cigarette, and sidestream smoke, which comes from the burning tip of the cigarette. Second-hand smoke consists mainly of sidestream smoke, which is about four times more toxic than mainstream smoke, although people inhale it in a more diluted form. This is because sidestream smoke contains much higher levels of many of the poisons and cancer-causing chemicals in cigarettes, including: up to three times as much carbon monoxidecarbon monoxide five times more cadmiumcadmium 3-10 times more polycyclic aromatic hydrocarbonspolycyclic aromatic hydrocarbons times more nitrosaminesnitrosamines about 15 times more benzenebenzene times more ammoniaammonia
Smoking in public places In February 2006, MPs voted by a massive majority to make public spaces, including pubs and private members' clubs, smokefree. This move will help to protect workers from the harmful effects of second-hand smoke and has been hailed as a large advance in public health. Since the ban was brought into place, England has seen the largest ever fall in smoking rates. In the first year of the ban, about 400,000 people quit smoking and scientists have estimated that the new laws will prevent about 40,000 deaths from smoking-related diseases over the next decade.prevent about 40,000 deaths Our Policy section has more information on the vote for smokefree public places, Cancer Research UK's view on smokefree legislation, and the dangers of second-hand smoke.vote for smokefree public places
Smoking and cancer: Reasons to quit here are lots of good reasons to quit. Everyone's motivations to stop will be different. Here are a few ideas to get you started.
Improve your health, whatever your age Giving up smoking at any age will increase your life expectancy, provided you stop before you develop cancer or another serious disease. The sooner you give up smoking the better. After: 20 minutes - your blood pressure and pulse return to normal 8 hours - nicotine, carbon monoxide and oxygen levels in your blood begin to return to normal 2 days - your lungs start to clear and your sense of taste and smell begin to return 3 days - breathing is easier and your energy levels increase 2-12 weeks - circulation improves and exercise gets easier 3-9 months - breathing problems, coughing, shortness of breath and wheezing improve 5 years - risk of having a heart attack falls to about half that of a smoker 10 years - risk of lung cancer falls to about half that of a smoker. You have the same risk of a heart attack as someone who has never smoked.
Save yourself thousands of pounds Smoking is very expensive. At today's rates, smoking around twenty cigarettes a day for the next twenty years would cost you over £40,000. Write down how much you spend on cigarettes every day for a week. Then work out how much your smoking costs you every year. Think what else you could do with the money.
Look after those around you If you smoke, you may be exposing your friends, partner or children to your smoke and endangering their health. Smoking may reduce your fertility and your chances of having a baby. And of course, smoking around your children (or during pregnancy) can harm their health. If children are exposed to tobacco smoke, they have a higher risk of breathing difficulties and cot death - the sudden and unexpected death of young babies.cot death
Stop the stress and the guilt More and more buildings are now non-smoking so finding a place to smoke can be quite stressful. How many times have you felt anxious because you didnt know when you were going to get your next cigarette? Think how nice it would be not to get stressed about where you can go to smoke. Smokers often feel guilty. You may be trying to hide your smoking from your partner or children. Have you seen people looking at you disapprovingly when you smoke in public? Sometimes feeling guilty about smoking means that you don't enjoy cigarettes as much as you did. Giving up could make you feel more in control and better about yourself.
Look younger and more attractive Smoking ages your skin. It also makes you smell of smoke and stains your fingers and teeth. And in the long term, smoking could damage your circulation leading to gangrene and even amputation. So give up now before its too late.