tobacco

tobacco

 [tah-bak´o]

the dried prepared leaves of Nicotiana tabacum, an annual plant widely cultivated in the United States, the source of various alkaloids, the principal one being nicotine. See also smoking and nicotine poisoning.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

to·bac·co

(tō-bak'ō),

An herb of South American origin, Nicotiana tabacum, which has large ovate to lanceolate leaves and terminal clusters of tubular white or pink flowers. Tobacco leaves contain 2-8% of nicotine and are the source of smoking and chewing tobacco or snuff. Tobacco smoke contains nicotine, carbon monoxide (4%), nitric oxide, and numerous aromatic hydrocarbons and other substances known to be carcinogens, including benzo[a]pyrene, β-naphthylamine, and nitrosamines.

Cigarette smoking is the leading preventable cause of disease and death in the U.S., being responsible for approximately 440,000 deaths (20% of all deaths) each year, and approximately $157 billion in health-related economic losses. Smoking two packages of cigarettes a day reduces life span by 8.3 years. Smoking tobacco in any form (cigarettes, cigars, pipe) is a strong independent risk factor for atherosclerosis, acute myocardial infarction, unstable angina, stroke, and sudden death. Tobacco is responsible for 81,000 deaths annually due to ischemic heart disease (including 45% of all deaths due to coronary artery disease in men under 65) and more than 50% of all strokes in both sexes before age 65. Smoking lowers HDL cholesterol and raises LDL and VLDL cholesterol, and increases the risk of intermittent claudication and aortic aneurysm. It may cause as much as a 30-fold increase in the risk of thromboembolic disease in women taking oral contraceptives. Smoking is responsible for 124,000 deaths each year due to lung cancer, and markedly increases the risk of other cancers, particularly those of the oral cavity, larynx, esophagus, kidney, bladder, uterine cervix, and pancreas. Cigarette smoking is the principal cause of chronic bronchitis and pulmonary emphysema. Involuntary or passive smoking (inhalation by nonsmokers of second-hand or sidestream smoke) causes 53,000 deaths annually, 37,000 of them due to coronary artery disease. Maternal smoking during pregnancy is associated with increased risk of miscarriage, stillbirth, and low birth weight. Children of smokers are at increased risk of sudden infant death syndrome, meningococcal meningitis, and dental caries. Use of smokeless tobacco (chewing tobacco or snuff applied to the buccal mucosa) greatly increases the risk of cancer and premalignant lesions of the oral cavity. Nicotine use is powerfully addictive, leading to habituation, tolerance, and dependency. In the U.S., 90% of smokers become habituated to tobacco before age 21 and 3,000 children begin smoking each day. The likelihood of becoming and remaining a smoker increases in inverse proportion to the number of years of education completed. Quitting smoking decreases the risk of death from all causes by 30%. Effective strategies for smoking cessation include behavior modification therapy, nicotine replacement (gum, skin patches, inhaler, nasal spray), hypnosis, and drug therapy (bupropion, clonidine, nortriptyline), but the relapse rate 3 months after smoking cessation is 60%.

Farlex Partner Medical Dictionary © Farlex 2012

tobacco

Public health Any product prepared from the dried leaves of Nicotiana tabacum, rich in the addictive alkaloid, nictoine Tobacco mortality–US ±425K/yr; cardiovascular deaths ±180K/yr; lung CA deaths ±120K/yr; 2^nd-hand smoke deaths 9K/yr. See Black tobacco, Blonde tobacco, Environmental tobacco smoke, Nicotine, Smokeless tobacco, Smoking.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

tobacco

Dried leaves of the plant Nicotina tabacum. Tobacco contains the drug NICOTINE for the effects of which it is smoked, chewed or inhaled as a powder (snuff). All these activities are dangerous. Cigarette smoking, in particular, is responsible for a greatly increased risk of cancer of the lung, mouth, bladder and pancreas and for an increased likelihood of chronic BRONCHITIS, EMPHYSEMA, coronary artery disease and disease of the leg arteries. Smoking is also harmful during pregnancy, leading to smaller and less healthy babies.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

to·bac·co

(tŏ-bak'ō)

Herb of South American origin, Nicotiana tabacum, which has large ovate to lanceolate leaves; leaves contain 2-8% nicotine and are source of smoking tobacco, chewing tobacco, and snuff. Tobacco smoke contains nicotine, carbon monoxide (4%), nitric oxide, and numerous aromatic hydrocarbons and other substances known to be carcinogens.

Medical Dictionary for the Dental Professions © Farlex 2012