The other major identified carcinogens in tobacco smoke are polynuclear aromatic hydrocarbons, aromatic amines, nitrosamines and catechol. It also contains many potent pulmonary irritants and ciliotoxins. Chronic smokers show abnormalities of pulmonary function tests. Smoking causes chronic bronchitis and emphysema. It has been associated with an increased incidence of respiratory infections and death from influenza and pneumonia.
Smoking is the single most important cause of cancer.
The risk of lung cancer is 10 times more in men who smoke one pack a day and 25 times more in those who smoke two packs a day as compared to nonsmokers. It also contributes to the development of oral, laryngeal, esophageal, gastric, pancreatic, kidney and bladder cancers. There is increased incidence of gastric and duodenal ulcers and chronic mouth ulcers in people who smoke. It is a risk factor for development of strokes. Smoking in wome n is associated with delayed conception and increased incidence of ectopic pregnancy.