The effects of tobacco on health are significant, depending on the way the tobacco is used (smoked, snuffed or chewed) and the amount. Major health effects of smoking, the most common use of tobacco, include an increased risk in lung cancer and cardiovascular disease. The World Health Organization estimated in 2002 that in developed countries, 26% of male deaths and 9% of female deaths were attributable to smoking. Similarly, 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."
Regular smokers are estimated to live to 2.5 to 10 years less than nonsmokers. About one-half of male smokers will die of illness due to smoking. Tobacco related illnesses kill 440,000 USA citizens per year, about 1,205 per day, making it the leading cause of preventable death in the U.S. The World Health Organization has stated that tobacco may cause up to a billion people this century.
The main health risks in tobacco pertain to diseases of the cardiovascular system, in particular smoking being a major risk factor for a myocardial infarction (heart attack), diseases of the respiratory tract such as Chronic Obstructive Pulmonary Disease (COPD) and emphysema, and cancer, particularly lung cancer and cancers of the larynx and mouth. 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 came a virtual epidemic of lung cancer.
Many forms of cancer, particularly lung cancer, cancer of the kidney, cancer of the larynx and head and neck, breast cancer, bladder, esophagus, pancreas, and stomach. There is some evidence suggesting an increased risk of myeloid leukemia, squamous cell Sino nasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancers of the gall bladder, adrenal gland and small intestine. Cardiovascular disease, Stroke, Peripheral vascular disease, Respiratory ailments, Common cold and bronchitis, Chronic obstructive pulmonary disease, emphysema and chronic bronchitis in particular, Birth defects of pregnant smokers' offspring, Impotence are the common diseases linked to smoking tobacco cigarettes.