Smoking is widely known to cause cancers of the lungs, digestive system, liver, and other organs, but tobacco smoke poses many other threats. Tobacco smoke contains more than 7,000 chemicals and compounds; 70 of these cause cancer, and hundreds are dangerous in other ways to smokers and to those around them.
Risks to smokers
Smokers have a greater risk of heart disease than do nonsmokers. This is because tobacco smoke causes blood vessels to thicken and narrow, resulting in high blood pressure and damage to the walls of veins and arteries. Smoking also causes the platelets in the blood to congeal and form clots, which line the walls of blood vessels and block the steady flow of blood. Coronary heart disease occurs when these clots form a plaque along the walls of the heart’s arteries, cutting off the blood supply and triggering a heart attack. Peripheral heart disease is caused by clotting in the legs or arms. If left untreated, peripheral heart disease can cause cramping, pain, and fatigue in the limb and eventually gangrene, which may require amputation.
The combination of high blood pressure and blood clotting from tobacco smoke can also induce a stroke, where loss of blood or ruptured blood vessels in the brain result in cell death.
Smoking also has been linked to type 2 diabetes, and the likelihood of developing the disease increases with the number of cigarettes smoked per day. Smoking can also worsen conditions such as nerve damage and kidney disease in people who already have diabetes. In addition, smoking can trigger autoimmune disorders such as Crohn disease and rheumatoid arthritis, where the immune system mistakenly attacks the body’s own tissues.
The chemicals in smoke can also affect vision. Smoking doubles the risk of developing age-related macular degeneration, a weakening of the central retina in the eye that leads to loss of vision. Smoking also increases the chances of cataracts and optic nerve damage.
Risks to nonsmokers
In addition to its extensive list of harmful effects to the smoker, tobacco smoke also endangers others. Pregnant women who smoke place their babies at risk for complications such as tissue damage, premature delivery, and death. Nicotine and carbon monoxide from tobacco smoke inhaled by pregnant women are especially harmful to fetuses, constricting the flow of blood and choking off their oxygen supply. Babies born to mothers who smoke have lower birth weights as a result of their underdeveloped bodies, increasing the risk of heart defects, lung damage, and impaired brain development. Finally, smoking while pregnant increases the chances of miscarriage and stillbirth. Yet despite the severe consequences, studies by the U.S. Centers for Disease Control and Prevention (CDC) indicate that less than half of smokers who become pregnant quit during pregnancy.
Parents who smoke also put their children at risk from secondhand smoke. Babies are especially vulnerable because the chemicals in tobacco smoke constrain their blood vessels and interfere with their brains’ ability to regulate breathing. As a result, babies who live with a smoker are two to four times more likely to die from sudden infant death syndrome. In addition, growing up with a smoker increases a child’s chances of developing bronchitis, pneumonia, and asthma. Even if a child with asthma does not live with a smoker, exposure to secondhand smoke can trigger asthma attacks, and frequent exposure increases the number and severity of these attacks.
Among adults, exposure to secondhand smoke can pose health risks similar to those of smoking. Frequent exposure increases the chances of cardiovascular disease by 25%–30% and the risk of stroke by 20%–30%. Individuals with heart disease risk having a heart attack when even briefly exposed to secondhand smoke because the smoke immediately constricts their blood vessels.
Risk of death
CDC statistics indicate that the average loss of lifespan for smokers is 13.2 years for men and 14.5 years for women. Smoking is the leading cause of preventable death in the United States, causing an estimated 480,000 deaths annually. Of those deaths, 41,000 are linked directly to secondhand smoke. If you smoke, committing yourself to breaking the habit could be one of the most important decisions you ever make, for yourself and for others.
For more information, ask your doctor, call askMDAnderson at 877-632-6789, visit the CDC Web site at www.cdc.gov/tobacco, or visit MD Anderson’s Tobacco Treatment Program at www.mdanderson.org/quitnow.
– C. Graber
OncoLog, November-December 2015, Volume 60, Issue 11-12