Tobacco smoking is the act of burning dried or cured leaves of the tobacco plant and inhaling the smoke for pleasure, for ritualistic or social purposes, self-medication, as well as to satisfy a physiological dependence on nicotine. Tobacco use by Native Americans throughout North and South America dates back to 2000BC and there are depictions of ancient Mayans smoking a crude cigar[citation needed]. The practice was brought back to Europe by the crew of Christopher Columbus. Tobacco smoking took hold in Spain and was introduced to the rest of the world, via trade.Tobacco smoke contains nicotine, an addictive stimulant and euphoriant. The effect of nicotine in first time or irregular users is an increase in alertness and memory, and mild euphoria. In chronic users, nicotine simply relieves the symptoms of nicotine withdrawal: confusion, restlessness, anxiety, insomnia, and dysphoria. Nicotine also disturbs metabolism and suppresses appetite. This is because nicotine, like many stimulants, increases blood sugar.Medical research has determined that chronic tobacco smoking can lead to many health problems, particularly lung cancer, emphysema, and cardiovascular disease.
Cigarette
Cigarette smoking is the most common form of tobacco consumption. Because of the curing process, the smoke is mild enough to inhale in overdose quantities, unlike cigar or pipe tobacco. Cigarettes also contain a number of additives, particularly to enhance taste. "Roll ups" are also very popular, particularly in European countries; these are prepared from loose tobacco, cigarette papers and filters all bought separately. Cigarettes are smoked by some with a cigarette holder. (See also Beedi).
Cigar
A cigar is generally puffed, not inhaled. Cigars come in many shapes and sizes, the most common being the "Corona", "Cigarillo", and "Robusto". The tobacco used is grown throughout the Caribbean in places such as the Dominican Republic, Nicaragua, Honduras, Jamaica, and Cuba. Cigars generally come available in 2 categories in reference to color, "Natural" and "Maduro". "Natural" shades are ones that do not undergo a further fermenting process, unlike "Maduro" which in it's construction involves a further fermenting process to darken and strengthen (in taste) the leaf.
Pipe
A pipe for smoking typically consists of a small chamber (bowl) for combustion of the substance to be smoked and a thin stem (shank) that ends in a mouthpiece (also called a bit). Pipes are made from a variety of materials (some obscure): briar, corncob, meerschaum, clay, wood, glass, gourd, bamboo, and various other materials, such as metal. Tobacco used for smoking pipes is often chemically treated to change smell and taste not available in other commercial tobacco products. Many of these are mixtures using staple ingredients of variously cured Burley and Virginia tobaccos which are mixed with tobaccos from different areas, such as Oriental or Balkan locations. Latakia (a fire-cured tobacco of Cypriot or Syrian origin), Perique (only grown in St. James Parish, Louisiana) or combinations of Virginia and Burley tobaccos of African, Indian, or South American origins. Traditionally, many U.S. tobaccos are made of American Burley with artificial sweeteners and flavorings added to create an artificial "aromatic" smell, whereas "English" blends are based on natural Virginia tobaccos enhanced with Oriental and other natural tobaccos. There is a growing tendency towards "natural" tobaccos which derive their aromas from blending with spice tobaccos alone and historically-based curing processes.
Pipes can range from the simple machine-made briar pipe to handmade and artful implements created by pipe-makers which can be expensive collector's items. The popularity of pipe smoking in Western countries has declined in recent years under the onslaught of cigarette advertising. However, it has also enjoyed a resurgence of late among younger and middle aged smokers who find its contemplative nature and age-transcendent status as "hobby not habit" to be both thoroughly enjoyable and stress-relieving[citation needed]. As many pipe-smokers say, "We don't inhale."
Hookah
A hookah (or sheesha) is a type of traditional Middle Eastern and South Asian water pipe, which operates by water-filtration and indirect heat. Hookahs are most popular in the Middle East, but form a niche market in many other places. In other contexts, hookahs are used to smoke cannabis, hashish or opium.
Typically, tobacco is smoked from a hookah by placing richly flavored tobaccos in the smoking bowl, covering it with foil, and placing a coal on top of the foil. This keeps the tobacco from burning, and allows it to bake. The resulting vapors are further cooled by the hookah water and filtered by a bubbling action in the basin of the hookah , resulting in a moist, warm smoke with very few dangerous chemicals that are found by burning the tobacco. The Al-Waha, Al Fakher, and Nakhla tobacco companies compete for market share in the Middle East by producing increasingly luxurious flavored tobaccos for use in the hookah. Some flavors include the traditional apple, grape, double apple, orange, strawberry, cherry, mango, vanilla, and melon flavors; as well as more modern flavors of cola, coconut, cappuccino, and banana milk.
Health effects
Establishing a link between smoking and health effects
As the use of tobacco became popular in Europe, some people became concerned about its negative effects. One of the first was King James I of Great Britain. In his 1604 treatise, A Counterblaste to Tobacco, King James observed that smoking was:
[a] custom loathsome to the eye, hateful to the Nose, harmful to the brain, dangerous to the Lungs, and in the blacke stinking fume thereof, neerest resembling the horrible Stigian smoke of the pit that is bottomelesse.
The late-19th century invention of automated cigarette-making machinery in the American South made possible mass production of cigarettes at low cost, and cigarettes became elegant and fashionable among society men as the Victorian era gave way to the Edwardian. In 1912, American Dr. Isaac Adler was the first to strongly suggest that lung cancer is related to smoking.[4] In 1929, Fritz Lickint of Dresden, Germany, published a formal statistical evidence of a lung cancer–tobacco link, based on a study showing that lung cancer sufferers were likely to be smokers. Lickint also argued that tobacco use was the best way to explain the fact that lung cancer struck men four or five times more often than women (since women smoked much less).
Prior to World War I, lung cancer was considered to be a rare disease, which most physicians would never see during their career. With the postwar rise in popularity of cigarette smoking, however, came a virtual epidemic of lung cancer.
In 1950, Dr. Richard Doll published research in the British Medical Journal showing a close link between smoking and lung cancer. Four years later, in 1954 the British Doctors Study, a study of some 40 thousand doctors over 20 years, confirmed the suggestion, based on which the government issued advice that smoking and lung cancer rates were related. The British Doctors Study lasted till 2001, with result published every ten years and final results published in 2004.
Health risks of smoking
The main health risks in tobacco pertain to diseases of the cardiovascular system, in particular myocardial infarction (heart attack), diseases of the respiratory tract such as Chronic Obstructive Pulmonary Disease (COPD), asthma, emphysema, and cancer, particularly lung cancer and cancers of the larynx and tongue.
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to smoke as well as the amount smoked. However, if someone stops smoking, then these chances gradually decrease as the damage to their body is repaired. A year after quitting, the risk of contracting heart disease is half that of a continuing smoker.
The health risks of smoking are not uniform across all smokers. Risks vary according to amount of tobacco smoked, with those who smoke more at greater risk. Light smoking is still a health risk. According to the Surgeon General of The United States, mortality rates for pipe smokers and cigar smokers who smoke less than five cigars per day are roughly the same as for non-smokers. The data regarding smoking to date focuses primarily on cigarette smoking, which even by conservative estimates increases mortality rates by 40%. Men who smoke 10-19 cigarettes a day have a 70% increase in mortality rates, men who smoke 20-39 cigarettes a day have an increase in mortality rate by 90%, for men smoking two packs a day or more, their mortality rates increased 120%. Some studies suggests that hookah smoking is considered to be safer than other forms of smoking. However, water is not effective for removing all relevant toxins, e.g. the carcinogenic aromatic hydrocarbons are not water-soluble. Several negative health effects are linked to hookah smoking and studies indicate that it is likely to be more harmful than cigarettes, due in part to the volume of smoke inhaled. In addition to the cancer risk, there is some risk of infectious disease resulting from pipe sharing, and other risks associated with the common addition of other psychoactive drugs to the tobacco. According to the Canadian Lung Association, tobacco kills between 40,000–45,000 Canadians per year, more than the total number of deaths from AIDS, traffic accidents, suicide, murder, fires and accidental poisoning. The United States' Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide".
Carcinogenicity
Smoke, or any partially burnt organic matter, is carcinogenic (cancer-causing). The damage a continuing smoker does to their lungs can take up to 20 years before its physical manifestation in lung cancer. Women began smoking later than men, so the rise in death rate amongst women did not appear until later. The male lung cancer death rate decreased in 1975 — roughly 20 years after the fall in cigarette consumption in men. A fall in consumption in women also began in 1975 but by 1991 had not manifested in a decrease in lung cancer related mortalities amongst women.
The carcinogenity of tobacco smoke is not explained by nicotine per se, which is not carcinogenic or mutagenic. However , it inhibits apoptosis, therefore accelerating existing cancers. Also, NNK, a nicotine derivative converted from nicotine, can be carcinogenic. Chronic obstructive pulmonary disease (COPD) caused by smoking, known as tobacco disease, is a permanent, incurable reduction of pulmonary capacity characterized by shortness of breath, wheezing, persistent cough with sputum, and damage to the lungs, including emphysema and chronic bronchitis
Effects on the heart
Smoking contributes to the risk of developing heart disease. All smoke contains very fine particulates that are able to penetrate the alveolar wall into the blood and exert their effects on the heart in a short time.
Inhalation of tobacco smoke causes several immediate responses within the heart and blood vessels. Within one minute the heart rate begins to rise, increasing by as much as 30 percent during the first 10 minutes of smoking. Carbon monoxide in tobacco smoke exerts its negative effects by reducing the blood’s ability to carry oxygen.
Smoking tends to increase blood cholesterol levels. Furthermore, the ratio of high-density lipoprotein (the “good” cholesterol) to low-density lipoprotein (the “bad” cholesterol) tends to be lower in smokers compared to non-smokers. Smoking also raises the levels of fibrinogen and increases platelet production (both involved in blood clotting) which makes the blood viscous. Carbon monoxide binds to haemoglobin (the oxygen-carrying component in red blood cells), resulting in a much stabler complex than haemoglobin bound with oxygen or carbon dioxide--the result is permanent loss of blood cell functionality. Blood cells are naturally recycled after a certain period of time, allowing for the creation of new, functional erythrocytes. However, if carbon monoxide exposure reaches a certain point before they can be recycled, hypoxia (and later death) occurs. All these factors make smokers more at risk of developing various forms of arteriosclerosis. As the arteriosclerosis progresses, blood flows less easily through rigid and narrowed blood vessels, making the blood more likely to form a thrombosis (clot). Sudden blockage of a blood vessel may lead to an infarction (e.g. stroke). However, it is also worth noting that the effects of smoking on the heart may be more subtle. These conditions may develop gradually given the smoking-healing cycle (the human body heals itself between periods of smoking), and therefore a smoker may develop less significant disorders such as worsening or maintenance of unpleasant dermatological conditions, e.g. eczema, due to reduced blood supply. Smoking also increases blood pressure and weakens blood vessels
Smoker's attitudes
Nicotine is an addictive stimulant and is one of the main factors leading to continued tobacco smoking. Although the percentage of the nicotine inhaled with tobacco smoke is quite small (most of the substance is destroyed by the heat) it is still sufficient to cause physical and/or psychological dependence.
Prior to habituation, tobacco smokers often focus on the reinforcing properties of smoking rather than the associated health risks. The diseases caused by smoking surface relatively later in life. As a result, they do not serve to deter smoking given the immediate gratification offered by smoking.
Some smokers argue that the depressant effect of smoking allows them to calm their nerves, often allowing for increased concentration. This, however, is only partly true. According to the Imperial College London, "Nicotine seems to provide both a stimulant and a depressant effect, and it is likely that the effect it has at any time is determined by the mood of the user, the environment and the circumstances of use. Studies have suggested that low doses have a depressant effect, whilst higher doses have stimulant effect." However, it is impossible to differentiate a drug effect brought on by nicotine use, and the alleviation of nicotine withdrawal.
Passive smoking
Passive or involuntary smoking occurs when the exhaled and ambient smoke (otherwise known as environmental or secondhand smoke) from one person's cigarette is inhaled by other people. Passive smoking involves inhaling carcinogens, as well as other toxic components, that are present in secondhand tobacco smoke.
Secondhand smoke is also known to harm children, infants and reproductive health through acute lower respiratory tract illness, asthma induction and exacerbation, chronic respiratory symptoms, middle ear infection, lower birth weight babies, and Sudden Infant Death Syndrome. In a study released on February 12, 2007 warning signs for cardiovascular disease are higher in people exposed to secondhand tobacco smoke, adding to the link between "passive smoke" and heart disease. "Our study provides further evidence to suggest low-level exposure to secondhand smoke has a clinically important effect on susceptibility to cardiovascular disease," said Dr. Andrea Venn of University of Nottingham in Britain, lead author of the study.
According to the U.S. Surgeon General’s Report (Chapter 5; pages 180–194), secondhand smoke is connected to SIDS. Infants who die from SIDS tend to have higher concentrations of nicotine and cotinine (a biological marker for secondhand smoke exposure) in their lungs than those who die from other causes. Infants exposed to secondhand smoke after birth are also at a greater risk of SIDS.
Somatic and psychological effects
Nicotine is a highly addictive psychoactive chemical. When tobacco is smoked, most of the nicotine is pyrolyzed; a dose sufficient to cause mild somatic dependency and mild to strong psychological dependency remains. According to studies by Henningfield and Benowitz, overall nicotine is more addictive than cannabis, caffeine, ethanol, cocaine, and heroin when considering both somatic and psychological dependence. However, due to the stronger withdrawal effects of ethanol, cocaine and heroin, nicotine may have a lower potential for somatic dependence than these substances. A study by Perrine concludes that nicotine's potential for psychological dependency exceeds all other studied drugs - even ethanol, an extremely physically addictive substance with severe withdrawal symptoms that can be fatal. About half of Canadians who currently smoke have tried to quit. McGill University health professor Jennifer O'Loughlin stated that nicotine addiction can occur as soon as five months after the start of smoking.
Recent evidence has shown that smoking tobacco increases the release of dopamine in the brain, specifically in the mesolimbic pathway, the same neuro-reward circuit activated by drugs of abuse such as heroin and cocaine. This suggests nicotine use has a pleasurable effect that triggers positive reinforcement. One study found that smokers exhibit better reaction-time and memory performance compared to non-smokers, which is consistent with increased activation of dopamine receptors. Neurologically, rodent studies have found that nicotine self-administration causes lowering of reward thresholds--a finding opposite that of most other drugs of abuse (e.g. cocaine and heroin). This increase in reward circuit sensitivity persisted months after the self-administration ended, suggesting that nicotine's alteration of brain reward function is either long lasting or permanent. Furthermore, it has been found that nicotine can activate long term potentiation in vivo and in vitro. These studies suggests nicotine’s "trace memory" may contribute to difficulties in nicotine abstinence.
Mood and anxiety disorders
Recent studies have linked smoking to anxiety disorders, suggesting the correlation (and possibly mechanism) may be related to the broad class of anxiety disorders, and not limited to just depression. Current ongoing research are attempting to explore the addiction-anxiety relationship.
Data from multiple studies suggest that anxiety disorders such as depression play a role in cigarette smoking. A history of regular smoking was observed more frequently among individuals who had experienced a major depressive disorder at some time in their lives than among individuals who had never experienced major depression or among individuals with no psychiatric diagnosis. People with major depression are also much less likely to quit due to the increased risk of experiencing mild to severe states of depression, including a major depressive episode. Depressed smokers appear to experience more withdrawal symptoms on quitting, are less likely to be successful at quitting, and are more likely to relapse.
Health benefits of smoking
Some studies have discovered health benefits correlated with smoking. These studies observed a reduction in the occurrence of some diseases, but all such studies stressed that the benefits of smoking did not outweigh the risks.
Several types of "Smoker’s Paradoxes", (cases where smoking appears to have specific beneficial effects), have been observed; often the actual mechanism remains undetermined. Risk of ulcerative colitis has been frequently shown to be reduced by smokers on a dose-dependent basis; the effect is eliminated if the individual stops smoking. Smoking appears to interfere with development of Kaposi's sarcoma, breast cancer among women carrying the very high risk BRCA gene, preeclampsia, and atopic disorders such as allergic asthma. A plausible mechanism of action in these cases may be the nicotine in tobacco smoke acting as an anti-inflammatory agent and interfering with the disease process.
Evidence suggests that non-smokers are up to twice as likely as smokers to develop Parkinson's disease or Alzheimer's disease. A plausible explanation for these cases may be the effect of nicotine, a cholinergic stimulant, decreasing the levels of acetylcholine in the smoker's brain; Parkinson's disease occurs when the effect of dopamine is less than that of acetylcholine. In addition, nicotine stimulates the mesolimbic dopamine pathway (as do other drugs of abuse), causing and effective increase in dopamine levels. Opponents counter by noting that consumption of pure nicotine may be as beneficial as smoking without the risks associated with smoking e.g. CO poisoning.
Considering the high rates of physical sickness and deaths among persons suffering from schizophrenia, one of smoking's short term benefits is its temporary effect to improve alertness and cognitive functioning in that disease. It has been postulated that the mechanism of this effect is that schizophrenics have a disturbance of nicotinic receptor functioning.
Cigarette
Cigarette smoking is the most common form of tobacco consumption. Because of the curing process, the smoke is mild enough to inhale in overdose quantities, unlike cigar or pipe tobacco. Cigarettes also contain a number of additives, particularly to enhance taste. "Roll ups" are also very popular, particularly in European countries; these are prepared from loose tobacco, cigarette papers and filters all bought separately. Cigarettes are smoked by some with a cigarette holder. (See also Beedi).
Cigar
A cigar is generally puffed, not inhaled. Cigars come in many shapes and sizes, the most common being the "Corona", "Cigarillo", and "Robusto". The tobacco used is grown throughout the Caribbean in places such as the Dominican Republic, Nicaragua, Honduras, Jamaica, and Cuba. Cigars generally come available in 2 categories in reference to color, "Natural" and "Maduro". "Natural" shades are ones that do not undergo a further fermenting process, unlike "Maduro" which in it's construction involves a further fermenting process to darken and strengthen (in taste) the leaf.
Pipe
A pipe for smoking typically consists of a small chamber (bowl) for combustion of the substance to be smoked and a thin stem (shank) that ends in a mouthpiece (also called a bit). Pipes are made from a variety of materials (some obscure): briar, corncob, meerschaum, clay, wood, glass, gourd, bamboo, and various other materials, such as metal. Tobacco used for smoking pipes is often chemically treated to change smell and taste not available in other commercial tobacco products. Many of these are mixtures using staple ingredients of variously cured Burley and Virginia tobaccos which are mixed with tobaccos from different areas, such as Oriental or Balkan locations. Latakia (a fire-cured tobacco of Cypriot or Syrian origin), Perique (only grown in St. James Parish, Louisiana) or combinations of Virginia and Burley tobaccos of African, Indian, or South American origins. Traditionally, many U.S. tobaccos are made of American Burley with artificial sweeteners and flavorings added to create an artificial "aromatic" smell, whereas "English" blends are based on natural Virginia tobaccos enhanced with Oriental and other natural tobaccos. There is a growing tendency towards "natural" tobaccos which derive their aromas from blending with spice tobaccos alone and historically-based curing processes.
Pipes can range from the simple machine-made briar pipe to handmade and artful implements created by pipe-makers which can be expensive collector's items. The popularity of pipe smoking in Western countries has declined in recent years under the onslaught of cigarette advertising. However, it has also enjoyed a resurgence of late among younger and middle aged smokers who find its contemplative nature and age-transcendent status as "hobby not habit" to be both thoroughly enjoyable and stress-relieving[citation needed]. As many pipe-smokers say, "We don't inhale."
Hookah
A hookah (or sheesha) is a type of traditional Middle Eastern and South Asian water pipe, which operates by water-filtration and indirect heat. Hookahs are most popular in the Middle East, but form a niche market in many other places. In other contexts, hookahs are used to smoke cannabis, hashish or opium.
Typically, tobacco is smoked from a hookah by placing richly flavored tobaccos in the smoking bowl, covering it with foil, and placing a coal on top of the foil. This keeps the tobacco from burning, and allows it to bake. The resulting vapors are further cooled by the hookah water and filtered by a bubbling action in the basin of the hookah , resulting in a moist, warm smoke with very few dangerous chemicals that are found by burning the tobacco. The Al-Waha, Al Fakher, and Nakhla tobacco companies compete for market share in the Middle East by producing increasingly luxurious flavored tobaccos for use in the hookah. Some flavors include the traditional apple, grape, double apple, orange, strawberry, cherry, mango, vanilla, and melon flavors; as well as more modern flavors of cola, coconut, cappuccino, and banana milk.
Health effects
Establishing a link between smoking and health effects
As the use of tobacco became popular in Europe, some people became concerned about its negative effects. One of the first was King James I of Great Britain. In his 1604 treatise, A Counterblaste to Tobacco, King James observed that smoking was:
[a] custom loathsome to the eye, hateful to the Nose, harmful to the brain, dangerous to the Lungs, and in the blacke stinking fume thereof, neerest resembling the horrible Stigian smoke of the pit that is bottomelesse.
The late-19th century invention of automated cigarette-making machinery in the American South made possible mass production of cigarettes at low cost, and cigarettes became elegant and fashionable among society men as the Victorian era gave way to the Edwardian. In 1912, American Dr. Isaac Adler was the first to strongly suggest that lung cancer is related to smoking.[4] In 1929, Fritz Lickint of Dresden, Germany, published a formal statistical evidence of a lung cancer–tobacco link, based on a study showing that lung cancer sufferers were likely to be smokers. Lickint also argued that tobacco use was the best way to explain the fact that lung cancer struck men four or five times more often than women (since women smoked much less).
Prior to World War I, lung cancer was considered to be a rare disease, which most physicians would never see during their career. With the postwar rise in popularity of cigarette smoking, however, came a virtual epidemic of lung cancer.
In 1950, Dr. Richard Doll published research in the British Medical Journal showing a close link between smoking and lung cancer. Four years later, in 1954 the British Doctors Study, a study of some 40 thousand doctors over 20 years, confirmed the suggestion, based on which the government issued advice that smoking and lung cancer rates were related. The British Doctors Study lasted till 2001, with result published every ten years and final results published in 2004.
Health risks of smoking
The main health risks in tobacco pertain to diseases of the cardiovascular system, in particular myocardial infarction (heart attack), diseases of the respiratory tract such as Chronic Obstructive Pulmonary Disease (COPD), asthma, emphysema, and cancer, particularly lung cancer and cancers of the larynx and tongue.
A person's increased risk of contracting disease is directly proportional to the length of time that a person continues to smoke as well as the amount smoked. However, if someone stops smoking, then these chances gradually decrease as the damage to their body is repaired. A year after quitting, the risk of contracting heart disease is half that of a continuing smoker.
The health risks of smoking are not uniform across all smokers. Risks vary according to amount of tobacco smoked, with those who smoke more at greater risk. Light smoking is still a health risk. According to the Surgeon General of The United States, mortality rates for pipe smokers and cigar smokers who smoke less than five cigars per day are roughly the same as for non-smokers. The data regarding smoking to date focuses primarily on cigarette smoking, which even by conservative estimates increases mortality rates by 40%. Men who smoke 10-19 cigarettes a day have a 70% increase in mortality rates, men who smoke 20-39 cigarettes a day have an increase in mortality rate by 90%, for men smoking two packs a day or more, their mortality rates increased 120%. Some studies suggests that hookah smoking is considered to be safer than other forms of smoking. However, water is not effective for removing all relevant toxins, e.g. the carcinogenic aromatic hydrocarbons are not water-soluble. Several negative health effects are linked to hookah smoking and studies indicate that it is likely to be more harmful than cigarettes, due in part to the volume of smoke inhaled. In addition to the cancer risk, there is some risk of infectious disease resulting from pipe sharing, and other risks associated with the common addition of other psychoactive drugs to the tobacco. According to the Canadian Lung Association, tobacco kills between 40,000–45,000 Canadians per year, more than the total number of deaths from AIDS, traffic accidents, suicide, murder, fires and accidental poisoning. The United States' Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide".
Carcinogenicity
Smoke, or any partially burnt organic matter, is carcinogenic (cancer-causing). The damage a continuing smoker does to their lungs can take up to 20 years before its physical manifestation in lung cancer. Women began smoking later than men, so the rise in death rate amongst women did not appear until later. The male lung cancer death rate decreased in 1975 — roughly 20 years after the fall in cigarette consumption in men. A fall in consumption in women also began in 1975 but by 1991 had not manifested in a decrease in lung cancer related mortalities amongst women.
The carcinogenity of tobacco smoke is not explained by nicotine per se, which is not carcinogenic or mutagenic. However , it inhibits apoptosis, therefore accelerating existing cancers. Also, NNK, a nicotine derivative converted from nicotine, can be carcinogenic. Chronic obstructive pulmonary disease (COPD) caused by smoking, known as tobacco disease, is a permanent, incurable reduction of pulmonary capacity characterized by shortness of breath, wheezing, persistent cough with sputum, and damage to the lungs, including emphysema and chronic bronchitis
Effects on the heart
Smoking contributes to the risk of developing heart disease. All smoke contains very fine particulates that are able to penetrate the alveolar wall into the blood and exert their effects on the heart in a short time.
Inhalation of tobacco smoke causes several immediate responses within the heart and blood vessels. Within one minute the heart rate begins to rise, increasing by as much as 30 percent during the first 10 minutes of smoking. Carbon monoxide in tobacco smoke exerts its negative effects by reducing the blood’s ability to carry oxygen.
Smoking tends to increase blood cholesterol levels. Furthermore, the ratio of high-density lipoprotein (the “good” cholesterol) to low-density lipoprotein (the “bad” cholesterol) tends to be lower in smokers compared to non-smokers. Smoking also raises the levels of fibrinogen and increases platelet production (both involved in blood clotting) which makes the blood viscous. Carbon monoxide binds to haemoglobin (the oxygen-carrying component in red blood cells), resulting in a much stabler complex than haemoglobin bound with oxygen or carbon dioxide--the result is permanent loss of blood cell functionality. Blood cells are naturally recycled after a certain period of time, allowing for the creation of new, functional erythrocytes. However, if carbon monoxide exposure reaches a certain point before they can be recycled, hypoxia (and later death) occurs. All these factors make smokers more at risk of developing various forms of arteriosclerosis. As the arteriosclerosis progresses, blood flows less easily through rigid and narrowed blood vessels, making the blood more likely to form a thrombosis (clot). Sudden blockage of a blood vessel may lead to an infarction (e.g. stroke). However, it is also worth noting that the effects of smoking on the heart may be more subtle. These conditions may develop gradually given the smoking-healing cycle (the human body heals itself between periods of smoking), and therefore a smoker may develop less significant disorders such as worsening or maintenance of unpleasant dermatological conditions, e.g. eczema, due to reduced blood supply. Smoking also increases blood pressure and weakens blood vessels
Smoker's attitudes
Nicotine is an addictive stimulant and is one of the main factors leading to continued tobacco smoking. Although the percentage of the nicotine inhaled with tobacco smoke is quite small (most of the substance is destroyed by the heat) it is still sufficient to cause physical and/or psychological dependence.
Prior to habituation, tobacco smokers often focus on the reinforcing properties of smoking rather than the associated health risks. The diseases caused by smoking surface relatively later in life. As a result, they do not serve to deter smoking given the immediate gratification offered by smoking.
Some smokers argue that the depressant effect of smoking allows them to calm their nerves, often allowing for increased concentration. This, however, is only partly true. According to the Imperial College London, "Nicotine seems to provide both a stimulant and a depressant effect, and it is likely that the effect it has at any time is determined by the mood of the user, the environment and the circumstances of use. Studies have suggested that low doses have a depressant effect, whilst higher doses have stimulant effect." However, it is impossible to differentiate a drug effect brought on by nicotine use, and the alleviation of nicotine withdrawal.
Passive smoking
Passive or involuntary smoking occurs when the exhaled and ambient smoke (otherwise known as environmental or secondhand smoke) from one person's cigarette is inhaled by other people. Passive smoking involves inhaling carcinogens, as well as other toxic components, that are present in secondhand tobacco smoke.
Secondhand smoke is also known to harm children, infants and reproductive health through acute lower respiratory tract illness, asthma induction and exacerbation, chronic respiratory symptoms, middle ear infection, lower birth weight babies, and Sudden Infant Death Syndrome. In a study released on February 12, 2007 warning signs for cardiovascular disease are higher in people exposed to secondhand tobacco smoke, adding to the link between "passive smoke" and heart disease. "Our study provides further evidence to suggest low-level exposure to secondhand smoke has a clinically important effect on susceptibility to cardiovascular disease," said Dr. Andrea Venn of University of Nottingham in Britain, lead author of the study.
According to the U.S. Surgeon General’s Report (Chapter 5; pages 180–194), secondhand smoke is connected to SIDS. Infants who die from SIDS tend to have higher concentrations of nicotine and cotinine (a biological marker for secondhand smoke exposure) in their lungs than those who die from other causes. Infants exposed to secondhand smoke after birth are also at a greater risk of SIDS.
Somatic and psychological effects
Nicotine is a highly addictive psychoactive chemical. When tobacco is smoked, most of the nicotine is pyrolyzed; a dose sufficient to cause mild somatic dependency and mild to strong psychological dependency remains. According to studies by Henningfield and Benowitz, overall nicotine is more addictive than cannabis, caffeine, ethanol, cocaine, and heroin when considering both somatic and psychological dependence. However, due to the stronger withdrawal effects of ethanol, cocaine and heroin, nicotine may have a lower potential for somatic dependence than these substances. A study by Perrine concludes that nicotine's potential for psychological dependency exceeds all other studied drugs - even ethanol, an extremely physically addictive substance with severe withdrawal symptoms that can be fatal. About half of Canadians who currently smoke have tried to quit. McGill University health professor Jennifer O'Loughlin stated that nicotine addiction can occur as soon as five months after the start of smoking.
Recent evidence has shown that smoking tobacco increases the release of dopamine in the brain, specifically in the mesolimbic pathway, the same neuro-reward circuit activated by drugs of abuse such as heroin and cocaine. This suggests nicotine use has a pleasurable effect that triggers positive reinforcement. One study found that smokers exhibit better reaction-time and memory performance compared to non-smokers, which is consistent with increased activation of dopamine receptors. Neurologically, rodent studies have found that nicotine self-administration causes lowering of reward thresholds--a finding opposite that of most other drugs of abuse (e.g. cocaine and heroin). This increase in reward circuit sensitivity persisted months after the self-administration ended, suggesting that nicotine's alteration of brain reward function is either long lasting or permanent. Furthermore, it has been found that nicotine can activate long term potentiation in vivo and in vitro. These studies suggests nicotine’s "trace memory" may contribute to difficulties in nicotine abstinence.
Mood and anxiety disorders
Recent studies have linked smoking to anxiety disorders, suggesting the correlation (and possibly mechanism) may be related to the broad class of anxiety disorders, and not limited to just depression. Current ongoing research are attempting to explore the addiction-anxiety relationship.
Data from multiple studies suggest that anxiety disorders such as depression play a role in cigarette smoking. A history of regular smoking was observed more frequently among individuals who had experienced a major depressive disorder at some time in their lives than among individuals who had never experienced major depression or among individuals with no psychiatric diagnosis. People with major depression are also much less likely to quit due to the increased risk of experiencing mild to severe states of depression, including a major depressive episode. Depressed smokers appear to experience more withdrawal symptoms on quitting, are less likely to be successful at quitting, and are more likely to relapse.
Health benefits of smoking
Some studies have discovered health benefits correlated with smoking. These studies observed a reduction in the occurrence of some diseases, but all such studies stressed that the benefits of smoking did not outweigh the risks.
Several types of "Smoker’s Paradoxes", (cases where smoking appears to have specific beneficial effects), have been observed; often the actual mechanism remains undetermined. Risk of ulcerative colitis has been frequently shown to be reduced by smokers on a dose-dependent basis; the effect is eliminated if the individual stops smoking. Smoking appears to interfere with development of Kaposi's sarcoma, breast cancer among women carrying the very high risk BRCA gene, preeclampsia, and atopic disorders such as allergic asthma. A plausible mechanism of action in these cases may be the nicotine in tobacco smoke acting as an anti-inflammatory agent and interfering with the disease process.
Evidence suggests that non-smokers are up to twice as likely as smokers to develop Parkinson's disease or Alzheimer's disease. A plausible explanation for these cases may be the effect of nicotine, a cholinergic stimulant, decreasing the levels of acetylcholine in the smoker's brain; Parkinson's disease occurs when the effect of dopamine is less than that of acetylcholine. In addition, nicotine stimulates the mesolimbic dopamine pathway (as do other drugs of abuse), causing and effective increase in dopamine levels. Opponents counter by noting that consumption of pure nicotine may be as beneficial as smoking without the risks associated with smoking e.g. CO poisoning.
Considering the high rates of physical sickness and deaths among persons suffering from schizophrenia, one of smoking's short term benefits is its temporary effect to improve alertness and cognitive functioning in that disease. It has been postulated that the mechanism of this effect is that schizophrenics have a disturbance of nicotinic receptor functioning.
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