Tobacco is a plant that contains the drug nicotine, and products produced from the leaves of that plant for consumption by smoking or chewing. Its recreational qualities were discovered by native Americans and passed on to Europeans after the establishment of the first permanent English settlement in 1607. Tobacco is smoked for a euphoric high that relaxes the individual and provides a calming, social atmosphere. However, studies in the mid to late 20th century showed that tobacco causes lung cancer and many other types of respiratory diseases such as emphysema. Nicotine is also an addictive substance that is the subject of controversy.
The Native Americans were the first to use tobacco because the plant was native to the Americas. Tobacco when consumed in large quantities is a hallucinogen; therefore the Native Americans did not use it recreationally but instead used it as a hallucinogen during religious ceremonies. Tobacco was exported by John Rolfe, (husband of Pocahontas). It became known as a cash crop. The negative effects of tobacco such as lung cancer, bronchitis and foul odor are widely accepted today. Tobacco companies have genetically modified tobacco plants and added toxic chemicals to their products to make them more addictive, thus making the modern cigarette much more toxic than the original cultivated plant.
Nicotine is an alkaloid in tobacco that is responsible for the addictive nature of cigarette smoking and other tobacco use. Regular nicotine consumption leads to tolerance (i.e., higher doses are required to achieve the same effect), and withdrawal symptoms (e.g., irritability, restlessness, nicotine cravings) occur when use is discontinued. Intake elicits acute increases in heart rate and blood pressure, as well as respiratory rate, but also decreases the volume of blood flow by causing the constriction of blood vessels. Nicotine in cigarette smoke is very easily absorbed through the lungs and buccal tissue in the oral cavity, and reaches the brain about seven seconds after it is inhaled in cigarette smoke. After reaching the brain, it stimulates the release of a number of neurotransmitters, including dopamine, norepinephrine, serotonin, and acetylcholine. The increased availability of these chemicals in the brain leads to feelings of pleasure and mild euphoria, as well as increased alertness and concentration. The half-life of nicotine is approximately two hours.
Medications containing nicotine are also used to help smokers who are trying to quit. These are referred to as nicotine replacement therapy (NRT). The idea behind NRT is that it allows smokers to break the behavioral component of their smoking habit (e.g., becoming used to not smoking while driving) while gradually reducing the amount of nicotine in their bloodstream, thus minimizing the effects of physiological nicotine withdrawal. Several different forms of NRT are available, including a transdermal patch, chewing gum, and nasal spray. Nicotine has also been found to be a useful treatment for certain physical conditions, though the mechanisms are not well understood. Smoking has been associated with a lower risk of Kaposi's sarcoma. Nicotine also appears to have therapeutic benefit for individuals with ulcerative colitis and one form of epilepsy.
Nicotine has been shown in some medical studies to be more addictive than cocaine and even heroin. Tobacco is often used along with cocaine because the nicotine in tobacco greatly enhances the euphoria one receives from cocaine.
Cigarettes. Cigarettes are the most commonly used tobacco product. Approximately one of every five American adults is a current smoker, and about 438,000 Americans die annually due to the effects of smoking; about 38,000 of these deaths are attributed to secondhand smoke. While the prevalence of smoking has dropped dramatically in the past 50 years, the rate at which the prevalence is decreasing has slowed substantially Additionally, the rate of smoking in adolescents and young adults has been increasing since the mid-1990s. There are nearly 5,000 different chemicals in cigarette smoke, including over 60 carcinogens.
Cigars. Cigars are larger versions of cigarettes. The tobacco leaves are less finely cut and do not undergo as much post-harvest processing or curing. They are rarely (if ever) filtered, and most users do not inhale as deeply as they do cigarettes. Cigars are somewhat more socially acceptable to many people, often being reserved for special occasions. They are certainly not without health hazards - and share many in common with other tobacco products - but as a consequence of the different method of use, cigar users are relatively more prone to oral cancers than are cigarette users.
Smokeless tobacco (chewing or dipping tobacco) Smokeless tobacco (a form of snuff) is a less commonly used tobacco product, however, this market segment has not suffered as much as that for cigarettes. It is a safer (though not safe) alternative to cigarettes, and tobacco-cessation groups are divided on whether it should be promoted as such (though largely against). It is typically sold in small metal or plastic cans referred to colloquially as "tins", generally containing 1.1oz (34 grams) of chewing tobacco. It usually consists of moistened fermented tobacco with additional synthetic flavorings. The smokeless tobacco market has been involved in a several consolidations recently, with large (primarily cigarette) companies buying smaller manufacturers of smokeless tobacco. It is more like the cigarette market in that there are numerous brands with high visibility, common ones include Skoal (controlling about 30% of the U.S. domestic market), Copenhagen (both owned by the U.S. Smokeless Tobacco Company), as well as Grizzly and Kodiak (products of the Conwood Sales Company, a subsidiary of RJ Reynolds). Smokeless tobacco users are especially at risk for oral cancers.
Smoking has a significant negative health impact, and causes many dangerous and fatal conditions, including cancers, heart disease, and respiratory disease.
It has been estimated that cigarette smoking is responsible for 28% of all deaths in developed countries in the 35-69 age group, as well as 35% of all cancer deaths and 28% of all deaths due to vascular diseases. Smoking increases the risk of oral, pharyngeal, esophageal, laryngeal, lung, uterine, cervical, urinary, and kidney cancers.
Coronary heart disease is one of the biggest causes of death in the United States, and is 2-4 more likely in smokers than nonsmokers. Smokers are also 10 times more likely to develop peripheral vascular disease, which is a narrowing of the arteries. Additionally, smokers are twice as vulnerable to a stroke compared with nonsmokers. Smoking also negatively impacts the respiratory system. Approximately 90% of all deaths from chronic lung diseases are the result of smoking.
In addition, smoking has been shown to double the risk of Alzheimer's Disease.
Secondhand smoke refers to smoke that is inhaled by nonsmokers from the environment. It is a combination of smoke given off by cigarettes and other smoking implements that is not inhaled by smokers, as well as the smoke exhaled by smokers. The U.S. Environmental Protection Agency has classified secondhand smoke as a Group A carcinogen, meaning that it is known to cause cancer in humans. It has been reported that secondhand smoke causes 3,600 annual lung cancer deaths and between 22,700 and 69,600 heart disease deaths annually in the U.S.. According the the Surgeon General, even short-term exposure to secondhand smoke can have harmful effects on cardiovascular functioning. Some tobacco companies have disputed the findings regarding harm caused by secondhand smoke. For example, Imperial Tobacco's website states "...it is our view that the scientific evidence, taken as a whole, is insufficient to establish that other people's tobacco smoke is a cause of any disease". Other tobacco companies have acknowledged that secondhand smoke can be harmful, including Phillip Morris: "Public health officials have concluded that secondhand smoke from cigarettes causes disease...Phillip Morris USA believes that the public should be guided by the conclusions of public health officials...[and] that the conclusions of public health officials concerning environmental tobacco smoke are sufficient to warrant measures that regulate smoking in public places".
Tobacco use in the United States
Tobacco use varies regionally within the United States. In 2006, the most recent year for which data are available, adult tobacco use was highest in Kentucky, where 50% of adults used tobacco, followed by West Virginia (49%), Oklahoma (47%), Tennessee (47%), and Ohio (46%). States with the lowest rates of adult tobacco use in 2006 were Utah (1%), California (2%), Idaho (3%), Connecticut, (4%), and Massachusetts, (5%). 
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