Tobacco use has predominantly negative effects on human health and concern about health effects of tobacco has a long history. Research has focused primarily on cigarette tobacco smoking. Tobacco smoke contains more than 70 chemicals that cause cancer.
When tobacco is smoked, nicotine causes physical and psychological dependency. Cigarettes sold in underdeveloped countries tend to have higher tar content, and are less likely to be filtered, potentially increasing vulnerability to tobacco smoking related disease in these regions.
Tobacco use is the single greatest cause of preventable death globally. Tobacco use leads most commonly to diseases affecting the heart, liver and lungs.
Smoking Causes Cancer, Heart Disease, Emphysema
Smoking is a major risk factor for heart attacks , strokes , chronic obstructive pulmonary disease COPD including emphysema and chronic bronchitis , and several cancers particularly lung cancer , cancers of the larynx and mouth , bladder cancer , and pancreatic cancer.
It also causes peripheral arterial disease and high blood pressure. The effects depend on the number of years that a person smokes and on how much the person smokes. Starting smoking earlier in life and smoking cigarettes higher in tar increases the risk of these diseases. Also, environmental tobacco smoke, or secondhand smoke , has been shown to cause adverse health effects in people of all ages.
Several countries have taken measures to control the consumption of tobacco with usage and sales restrictions as well as warning messages printed on packaging. Additionally, smoke-free laws that ban smoking in public places such as workplaces, theaters, and bars and restaurants reduce exposure to secondhand smoke and help some people who smoke to quit, without negative economic effects on restaurants or bars.
The idea that tobacco use caused some diseases, including mouth cancers, was initially, in the late s and the s, widely accepted by the medical community. Case-control studies were published in Germany in and , and one in the Netherlands in , but widespread attention was first drawn by five case-control studies published in by researchers from the US and UK. These studies were widely criticized as showing correlation, not causality.
Follow up prospective cohort studies in the early s clearly found that that smokers died faster, and were more likely to die of lung cancer and cardiovascular disease. Smoking most commonly leads to diseases affecting the heart and lungs and will most commonly affect areas such as hands or feet with first signs of smoking related health issues showing up as numbness, with smoking being a major risk factor for heart attacks , chronic obstructive pulmonary disease COPD , emphysema , and cancer , particularly lung cancer , cancers of the larynx and mouth , and pancreatic cancer.
Among male smokers, the lifetime risk of developing lung cancer is This risk is significantly lower in nonsmokers: 1. With the postwar rise in popularity of cigarette smoking came a virtual epidemic of lung cancer.
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. Risks vary according to the amount of tobacco smoked, with those who smoke more at greater risk. Smoking so-called "light" cigarettes does not reduce the risk.
Smoking is the cause of about 5 million deaths per year. In the United States, cigarette smoking and exposure to tobacco smoke accounts for roughly one in five,  or at least , premature deaths annually.
It is estimated that there are between 1 and 1. In fact, cigarette factories are the most deadly factories in the history of the world. The primary risks of tobacco usage include many forms of cancer, particularly lung cancer ,  kidney cancer ,  cancer of the larynx and head and neck ,   bladder cancer ,  cancer of the esophagus ,  cancer of the pancreas  and stomach cancer. SCLC may originate from neuroendocrine cells located in the bronchus called Feyrter cells.
The risk of dying from lung cancer before age 85 is The corresponding estimates for lifelong nonsmokers are a 1. In smoking, long term exposure to compounds found in the smoke e. Chronic obstructive pulmonary disease COPD caused by smoking, is a permanent, incurable often terminal reduction of pulmonary capacity characterised by shortness of breath, wheezing, persistent cough with sputum , and damage to the lungs, including emphysema and chronic bronchitis.
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 negative effects by reducing the blood's ability to carry oxygen.
Health Effects Infographics
Smoking also increases the chance of heart disease , stroke , atherosclerosis , and peripheral vascular disease. According to a study by an international team of researchers , people under 40 are five times more likely to have a heart attack if they smoke. Exposure to tobacco smoke is known to increase oxidative stress in the body by various mechanisms, including depletion of plasma antioxidants such as vitamin C.
Recent research by American biologists has shown that cigarette smoke also influences the process of cell division in the cardiac muscle and changes the heart's shape. The usage of tobacco has also been linked to Buerger's disease thromboangiitis obliterans the acute inflammation and thrombosis clotting of arteries and veins of the hands and feet. Although cigarette smoking causes a greater increase in the risk of cancer than cigar smoking, cigar smokers still have an increased risk for many health problems, including cancer, when compared to non-smokers.
Smoking tends to increase blood cholesterol levels.
Tobacco and Health
Furthermore, the ratio of high-density lipoprotein HDL, also known as the "good" cholesterol to low-density lipoprotein LDL, also known as 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 thicker and more likely to clot.
Carbon monoxide binds to hemoglobin the oxygen-carrying component in red blood cells , resulting in a much stabler complex than hemoglobin 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 red blood cells. 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 hardening of the arteries.
Health effects of tobacco pdf
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 stroke or heart attack. 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.
Smoking also increases blood pressure and weakens blood vessels.
In addition to increasing the risk of kidney cancer, smoking can also contribute to additional renal damage. Smokers are at a significantly increased risk for chronic kidney disease than non-smokers.
A study of an outbreak of an H1N1 influenza in an Israeli military unit of healthy young men to determine the relation of cigarette smoking to the incidence of clinically apparent influenza, revealed that, of smokers, Influenza was also more severe in the smokers; The effect of cigarette smoking upon epidemic influenza was studied prospectively among 1, male college students.
Influenza incidence among smokers of 1 to 20 cigarettes daily was intermediate between non-smokers and heavy cigarette smokers. Surveillance of a influenza outbreak at a military base for women in Israel revealed that influenza symptoms developed in Smoking seems to cause a higher relative influenza-risk in older populations than in younger populations.
Smoking may substantially contribute to the growth of influenza epidemics affecting the entire population. Perhaps the most serious oral condition that can arise is that of oral cancer. However, smoking also increases the risk for various other oral diseases, some almost completely exclusive to tobacco users.
Health effects of tobacco
The National Institutes of Health , through the National Cancer Institute , determined in that "cigar smoking causes a variety of cancers including cancers of the oral cavity lip, tongue, mouth, throat , esophagus , larynx , and lung. Smokeless tobacco causes gingival recession and white mucosal lesions. Smokers have significantly greater loss of bone height than nonsmokers, and the trend can be extended to pipe smokers to have more bone loss than nonsmokers. Smoking has been proven to be an important factor in the staining of teeth.
Smoking is also linked to susceptibility to infectious diseases, particularly in the lungs pneumonia.
Smoking more than 20 cigarettes a day increases the risk of tuberculosis by two to four times,   and being a current smoker has been linked to a fourfold increase in the risk of invasive disease caused by the pathogenic bacteria Streptococcus pneumoniae. Smoking increases the risk of Kaposi's sarcoma in people without HIV infection. The incidence of impotence difficulty achieving and maintaining penile erection is approximately 85 percent higher in male smokers compared to non-smokers.
Smoking is harmful to the ovaries , potentially causing female infertility , and the degree of damage is dependent upon the amount and length of time a woman smokes. Nicotine and other harmful chemicals in cigarettes interfere with the body's ability to create estrogen , a hormone that regulates folliculogenesis and ovulation.
Also, cigarette smoking interferes with folliculogenesis, embryo transport, endometrial receptivity, endometrial angiogenesis , uterine blood flow and the uterine myometrium. American Psychologist stated, "Smokers often report that cigarettes help relieve feelings of stress. However, the stress levels of adult smokers are slightly higher than those of nonsmokers, adolescent smokers report increasing levels of stress as they develop regular patterns of smoking, and smoking cessation leads to reduced stress.
Far from acting as an aid for mood control, nicotine dependency seems to exacerbate stress. This is confirmed in the daily mood patterns described by smokers, with normal moods during smoking and worsening moods between cigarettes. Thus, the apparent relaxant effect of smoking only reflects the reversal of the tension and irritability that develop during nicotine depletion.
Dependent smokers need nicotine to remain feeling normal. Users report feelings of relaxation , sharpness, calmness , and alertness. Generally, the unpleasant symptoms will eventually vanish over time, with repeated use, as the body builds a tolerance to the chemicals in the cigarettes, such as nicotine. Smokers report higher levels of everyday stress. The deleterious mood effects of abstinence explain why smokers suffer more daily stress than non-smokers and become less stressed when they quit smoking.
Deprivation reversal also explains much of the arousal data, with deprived smokers being less vigilant and less alert than non-deprived smokers or non-smokers. Recent studies have shown a positive relationship between psychological distress and salivary cotinine levels in smoking and non-smoking adults, indicating that both firsthand and secondhand smoke exposure may lead to higher levels of mental stress.
Medical researchers have found that smoking is a predictor of divorce. The usage of tobacco can also create cognitive dysfunction. There seems to be an increased risk of Alzheimer's disease , although "case—control and cohort studies produce conflicting results as to the direction of the association between smoking and AD".
Most notably, some studies have found that patients with Alzheimer's disease are more likely not to have smoked than the general population, which has been interpreted to suggest that smoking offers some protection against Alzheimer's. However, the research in this area is limited and the results are conflicting; some studies show that smoking increases the risk of Alzheimer's disease. Some older analyses have claimed that non-smokers are up to twice as likely as smokers to develop Alzheimer's disease.
Researchers without tobacco lobby influence have concluded the complete opposite: Smokers are almost twice as likely as nonsmokers to develop Alzheimer's disease.