The Many Dangers of Tobacco Use
“Don’t smoke.”
In this day and age, we have all heard this refrain over and over from a very young age. From the high taxes on cigarettes and other tobacco products to the no-smoking public campaigns, it’s been drummed into heads (and our wallets) that smoking is bad for us. But why is it so bad? And why do so many people smoke anyway knowing that it’s bad for them?
Tobacco smoke is composed of over 7000 chemical compounds, 69 of which are known carcinogens. It includes a mixture of nicotine, hydrogen cyanide, formaldehyde, lead, arsenic, and more [1]. Many of these compounds are toxic individually, and the combined effect has led the US Environmental Protection Agency to classify environmental tobacco smoke as one of the most dangerous carcinogenic agents in 1992.
Smoking triggers negative side effects from the very first inhale. As the smoke travels through the airways and into the lungs, the high concentration of toxic substances stimulates the nerves in the lungs and triggers airway tightening, also known as bronchospasm. This is why smokers are more prone to coughing and producing phlegm to clear the irritants from the lung. Inhaled smoke continues to circulate around the body to affect every organ. For example, the sudden rush of nicotine into the system kick starts the adrenal glands to produce epinephrine (aka adrenaline). This, in turn, increases blood pressure, respiration, and heart rate. Importantly, it also activates pleasure pathways in the brain, and is the root cause of tobacco addiction. For many, that first puff of a cigarette or other tobacco products becomes the start of a long road to organ dysfunction as they continue to chase that nicotine-induced high.
Cancer
Tobacco use has become the leading preventable cause of premature death in the United States. The predominant reason is smoking-induced cancer, which accounts for at least 30% of all cancer deaths [2]. The toxic constituents of tobacco smoke change the DNA of cells to cause mutations of important genes that eventually leads to loss of normal growth and leads to cancerous tumor growth. While normal bodily systems can detect and eliminate cancerous cells, nicotine and other tobacco components can prevent the body from killing these mutated cells, and thus allows to tumor to grow unhindered. Lung cancer is, by far, the main smoking-related cancer with smoking accounting for about 80% of all lung cancer deaths. However, tobacco also heightens the risk up to 18 types of cancers such as leukemia and cancers of the head and neck, esophagus, bladder, pancreas, kidney, liver, and more.
Cardiovascular Disease
The initial effect of tobacco on blood pressure and heart rate unsurprisingly develops into cardiovascular disease with long-term smoking. The chemicals in tobacco smoke begin to inflame the endothelium, which the lining of blood vessels and contributes to fatty plaques and clots to begin building on the blood vessel wall. This is known as atherosclerosis. As time goes on, the plaque begins to grow larger and larger until the vessel is completely obstructed. At this point, blood can no longer deliver oxygen or other nutrients to the organs, and this can lead to potentially fatal events like heart attacks, stroke, or even vessel rupture.
Lung disease
As the first major organ to come into contact with tobacco smoke, the lungs unfortunately bear the brunt of the damage. As the smoke diffuses through the pulmonary tissue, the toxic particles irritate lung cells and destroy the cilia, which are tiny hair-like structures that line the lungs and clear mucus and debris to help prevent respiratory infection. This leads to the development of lung diseases such as chronic bronchitis, chronic obstructive pulmonary disease (COPD), emphysema, and pulmonary hypertension.
The Brain
Many pathophysiological symptoms of the brain are a result of the impact of tobacco on other organ systems. For example, when heart rate and blood pressure is affected, this increases the risk of cerebrovascular incidents such as strokes. However, scientists have also found a causative link between tobacco use and cognitive decline. Tobacco users are 30% more prone to developing dementia and often experience more rapid cognitive decline as they age compared to non-tobacco users. A 2017 study also found that long-term smoking results in brain tissue loss in the subcortical regions.
Tobacco is also associated with mental disorders. The constant exposure to nicotine exhausts the acetylcholine and dopamine receptors in the brain, which are proteins that activate the pleasure pathways. As a result, it requires increasing amounts of stimulus (e.g., greater amount of tobacco products consumed) to achieve that same level of positive feelings that resulted from the very first use. The nicotine-induced tolerance leads to feelings of anxiety, irritability, and depression when in withdrawal. This lends itself to a vicious negative feedback cycle, where there is an emotional dependence on tobacco consumption even while causing debilitating health problems.
The Aftermath
The systemic toxicity caused by tobacco use has made tobacco use the leading cause of preventable deaths in the world. Over 1.1 billion people worldwide still actively use tobacco products though tobacco use among young people has decreased dramatically.
Fortunately, it is never too late to quit. In fact, studies have shown that the health benefits of quitting smoking can be seen almost immediately [8]. The heart will immediately slow within 20 minutes after the last cigarette, carbon monoxide levels in the blood will return to normal within 12 hours and improve circulation and lung function can be seen within 3 months. Long term recovery is also possible, with the risks of a heart attack halved within a year and stroke risk brought down to be comparable to a nonsmoker within 5 to 15 years.
Quitting is not easy though. Withdrawal symptoms can be overwhelming and quickly make a smoker lapse and return to tobacco consumption. Fortunately, there are several options that can make the process more manageable. Nicotine replacement therapies, such as nicotine gum, patches, and lozenges, can help wean a smoker off tobacco use by providing the minimum nicotine needed to make withdrawal more tolerable but without all the other toxic components. Individual or group therapy support is also often recommended to obtain emotional support during withdrawal and lifestyle modification such as exercise, meditation, spending time with family and friends can all aid in reducing life stresses that also often contribute to smoking.
References
Centers for Disease Control and Prevention (US); National Center for Chronic Disease Prevention and Health Promotion (US); Office on Smoking and Health (US) How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General; Publications and Reports of the Surgeon General; Centers for Disease Control and Prevention (US): Atlanta (GA), 2010; ISBN 978-0-16-084078-4.
Centers for Disease Control and Prevention (US); National Center for Chronic Disease Prevention and Health Promotion (US); Office on Smoking and Health (US). How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. Atlanta (GA): Centers for Disease Control and Prevention (US); 2010. 7, Pulmonary Diseases
Disease Control Priorities, Third Edition (Volume 5): Cardiovascular, Respiratory, and Related Disorders; Prabhakaran, D., Anand, S., Gaziano, T.A., Mbanya, J.-C., Wu, Y., Nugent, R., Eds.; The World Bank, 2017; ISBN 978-1-4648-0518-9.
Durazzo, T.C.; Meyerhoff, D.J.; Yoder, K.K.; Murray, D.E. Cigarette Smoking Is Associated with Amplified Age-Related Volume Loss in Subcortical Brain Regions. Drug and Alcohol Dependence 2017, 177, 228–236, doi:10.1016/j.drugalcdep.2017.04.012.
Harms of Cigarette Smoking and Health Benefits of Quitting - NCI Available online: https://www.cancer.gov/about-cancer/causes-prevention/risk/tobacco/cessation-fact-sheet (accessed on 14 September 2022).
Reitsma, M.B.; Flor, L.S.; Mullany, E.C.; Gupta, V.; Hay, S.I.; Gakidou, E. Spatial, Temporal, and Demographic Patterns in Prevalence of Smoking Tobacco Use and Initiation among Young People in 204 Countries and Territories, 1990–2019. The Lancet Public Health 2021, 6, e472–e481, doi:10.1016/S2468-2667(21)00102-X.
What Happens When You Quit Smoking: A Timeline of Health Effects Available online: https://www.healthline.com/health/what-happens-when-you-quit-smoking (accessed on 14 September 2022).
Zhong, G.; Wang, Y.; Zhang, Y.; Guo, J.J.; Zhao, Y. Smoking Is Associated with an Increased Risk of Dementia: A Meta-Analysis of Prospective Cohort Studies with Investigation of Potential Effect Modifiers. PLoS One 2015, 10, e0118333, doi:10.1371/journal.pone.0118333.