What're the constituents of tobacco smoke?
Tobacco smoke is a complex mixture of several thousand chemical compounds – some in tiny quantities – that are the product of burning the ingredients of the tobacco product. These include particulates (tar) of sticky solids, gases such as carbon monoxide, and volatiles. Most importantly, the smoke contains nicotine – the addictive drug. This mixture is constantly changing as the smoke 'ages' - chemicals in the smoke and background atmosphere react with each other and
change under the effect of ultra-violet light. Tobacco smoke is estimated to contain over four thousand compounds, many of which are pharmacologically active, toxic, mutagenic and carcinogenic. The following major components of tobacco smoke have been identified as most likely to cause disease:
Nicotine: Nicotine is among the most toxic of all poisons and acts with great speed. The average lethal dose for an adult human is estimated to be between 30 - 60 milligrams (mg). Once relatively common due to its use in insecticides in the 1920s and 1930s. Nicotine is the pharmacological agent in the tobacco smoke that causes addiction among smokers. The addictive effect of nicotine is linked to its capacity to trigger the release of dopamine - a chemical in the brain that is associated with the feelings of pleasure. Recent research has suggested that in the long term, nicotine depresses the ability of the brain to experience please1. Thus, smokers need greater amounts of the drug to achieve the same levels of satisfaction. Smoking is therefore a form of self-medication: further smoking alleviates the withdrawal symptoms which set in soon after the effects of nicotine wear off. Its immediate physiological effects include increased heart rate and blood pressure, constriction of cutaneous blood vessels, and muscular, hormonal and metabolic effects. With prolonged exposure to nicotine, it may contribute (in combination with carbon monoxide) to increased platelet stickiness and aggregation and damage to the lining of the blood vessels, suggesting a potential role in causing coronary disease. Although nicotine does not appear to possess direct carcinogenic activity itself, it enables the formation of tobacco-specific nitrosamines, which are potent carcinogens.
Tar: "Tar" describes the particulate matter inhaled when the smoker draws on a lighted cigarette. Each particle is composed of a large variety of organic and inorganic chemicals consisting primarily of nitrogen, oxygen, hydrogen, carbon dioxide, carbon monoxide, and a wide range of volatile and semivolatile organic chemicals. In its condensate form, tar is a sticky brown substance which can stain smokers' fingers and teeth yellow brown. It also stains the lung tissue. Among the carcinogens or tumour initiators present in cigarettes smoke are the two major classes of tomour initiators: polycyclic aromatic hydrocarbons and tobacco-specific nitrosamines. Benzopyrene as a carcinogen, is a prominent polycyclic aromatic hydrocarbon found in tar.
Carbon monoxide (CO): Tobacco smoke contains carbon monoxide. Carbon monoxide is a colourless, odourless, poisonous gas. Carbon monoxide interferes with uptake of oxygen in the lungs and with its release from the blood to the tissues that need it. When carbon monoxide is inhaled it combines with the haemoglobin in the blood to form carboxylhaemoglobin. As carbon monoxide has a chemical affinity for haemoglobin over 200 times greater than that of oxygen, it binds preferentially with haemoglobin, thereby reducing the amount of oxygenated blood circulated to body organs and tissues. Thus, the oxygen transportation in the body is impaired. The amount of oxygen carried by the blood may be severely deprived in heavy smokers due to the effects of carbon monoxide. Oxygen levels may be reduced by as much as 15%. Carbon monoxide is strongly linked with the development of coronary heart diseases. It might occur through interference with myocardial oxygenation, increasing platelet stickiness, or promotion or atherosclerosis. Carbon monoxide also restricts the oxygen available to the foetus, contributing to the low weight of babies born to women who smoke. The baby in the womb cannot grow normally if deprived of oxygen.
Nitrogen oxides: Cigarette smoke contains oxides of nitrogen in relatively high levels. This gas is known to cause lung damage in experimental animals similar to that noted in smokers, and may be responsible for initiating lung damage leading to emphysema.
Hydrogen cyanide and other ciliatoxic agents: Hydrogen cyanide has a direct, deleterious effect on the cilia, part of the natural lung clearance mechanism in humans. Interference with this cleaning system can result in an accumulation of toxic agents in the lungs, thereby increasing the likelihood of developing disease. Other toxic agents in cigarette smoke which directly affect the cilia include acrolein, ammonia, nitrogen dioxide and formaldehyde.
Metals: Thirty metals have been detected in tobacco smoke, including nickel, arsenic, cadmium,(12) chromium and lead.(2) Arsenic and arsenic compounds and chromium and some chromium compounds are causally associated with cancer in humans, while nickel and cadmium and their compounds are probably carcinogenic to humans. Arsenic levels in tobacco have been elevated in the past due to the use of arsenical pesticides. Cadmium levels may be related to the presence of cadmium in phosphate fertilisers.
Radioactive compounds: The radioactive compounds found in highest concentration in cigarette smoke are polonium-210 and potassium-40. Other radioactive compounds present include radium-226, radium-228 and thorium-228. Radioactive compounds are well established as carcinogens.
More information on quitting smoking
How to quit smoking? - Many smokers know they need to quid smoking to avoid health risk. Smoking cessation is of the most importance for people who is suffering from unpleasant smoking symptoms.
What health effects are associated with smoking? - The main health risks in tobacco smoking pertain to diseases of the respiratory tract and also to diseases of the cardiovascular system, in particular smoking being a major risk factor for a myocardial infarction (heart attack).
What're the constituents of tobacco smoke? - Tobacco smoke is a complex mixture of several thousand chemical compounds. These include particulates (tar) of sticky solids, gases such as carbon monoxide, and volatiles. Most importantly, the smoke contains nicotine ĘC the addictive drug.
Smoking and lung cancer - Lung cancer is directly related to smoking. Over 40 carcinogens have been identified in cigarette smoke. The risk of developing lung cancer is directly related to the number of cigarettes smoked.
Smoking and cardiovascular disease - There are a number of cardiovascular diseases that can be related to smoking. They include heart disease, stroke, and peripheral vascular disease. Smoking aggravates and accelerates of the development of atherosclerotic lesions in the arterial walls.
Smoking and chronic obstructive pulmonary disease (COPD) - Chronic obstructive pulmonary disease (COPD) is a lung disease in which the lung is damaged, making it hard to breathe. Prolonged tobacco use causes lung inflammation and variable degrees of air sack (alveoli) destruction.
Other cancers caused by or associated with smoking - Cigarette smoking is a major cause of cancers of the oral cavity, oesophagus and larynx. Smoking is a cause of bladder cancer. Cigarette smoking is at least a contributory and may be a causal factor in the development of pancreatic cancer.
Women's health and smoking - Women smokers suffer all the consequences of smoking that men do such as increased of risk various cancers (lung, mouth, larynx, pharynx, esophagus, kidney, pancreas, kidney, and bladder) and respiratory diseases.
Harm to human body by smoking - Chemicals in tobacco cause damage to the macula (the most sensitive part of the retina, the back of the eye). Smoking is a risk factor for all cancers associated with the larynx, oral cavity and oesophagus.
What is passive smoking? - "Passive smoking" or "secondhand smoke" - also known as "environmental tobacco smoke" (ETS) or "involuntary smoking" - occurs when the ambient smoke from one person's cigarette is inhaled by other people.
Health hazards of passive smoking - Some of the immediate effects of passive smoking include eye irritation, headache, cough, sore throat, dizziness and nausea. Adults with asthma can experience a significant decline in lung function when exposed, while new cases of asthma may be induced in children whose parents smoke.
How to avoid passive smoking? - Let your visitors know your home is a smoke-free zone, request them to smoke outside. Ask your visitors to put off the cigarette before entering your room. Ask to be seated in non-smoking areas as far from smokers as possible when dining out.
What is a smoking addiction? - A smoking addiction means a person has formed an uncontrollable dependence on cigarettes to the point where stopping smoking would cause severe emotional, mental, or physical reactions.
Why quit smoking? - Smoking increases the risk of respiratory diseases such as emphysema, chronic bronchitis and chronic obstructive pulmonary disease (COPD). Smokers have twice the risk of dying of heart attacks, as do non-smokers.
How to stop smoking? - Quitting smoking is a lot like losing weight; it takes a strong commitment over a long period of time. Withdrawal from nicotine has two parts - the physical and the psychological.
Cigar smoking and health - A cigar is defined, for tax purposes, as "any roll of tobacco wrapped in leaf tobacco or in any substance containing tobacco," while a cigarette is "any roll of tobacco wrapped in paper or any substance not containing tobacco.
What smoking cessation medications are available? - Nicotine for NRT is available by prescription as an inhaler or nasal spray (Nicotrol Inhaler and Nicotrol NS).
Changes in body weight and smoking cessation - Smokers weigh, on average, around 3 kg less than non-smokers, although heavy smokers are more likely to be moderately or severely overweight. For many people, the fear of gaining weight prevents them from quitting smoking.
Health benefits of quitting smoking - Smoking cessation has major and immediate health benefits for men and women of all ages. The health benefits of smoking cessation far exceed any risks from the average 2.3 kg (5 pound) weight gain or any adverse psychological effects that may follow quitting.