Smoking DIseases

Fig. 1 - An ectopic pregnancy in the fallopian tubes

Premature Ageing and Gum Disease

One of the dermatological effects of tobacco smoke is premature ageing, in which collagen production is impaired, and certain enzymes are synthesised that degrade collagen. Collagen is an important protein for skin health, and its degradation accelerates the ageing of the skin.

Additionally, smokers are four times more likely to develop gum disease and periodontal issues. These issues occur because the toxins in tobacco smoke damage the connective tissue in your teeth, making them prone to structural loss and deterioration.

Second-hand Smoking

Not only does smoking inflict consequences upon the smoker, but also those around them that inhale the tobacco smoke. Research has shown that the risk of developing adverse effects of smoking increases to 30% for those who inadvertently inhale smoke. The WHO states that of the 8 million lives that die each year due to tobacco smoking, over 1.2 million individuals have been exposed to second-hand smoke.

Other Diseases

Cardiovascular disease, pulmonary complications and cancers are the leading causes of smoking-related deaths worldwide, with lung cancer being the leading disease caused by smoking. We will explore each disease type in the following section.

Diseases and Long-term Effects of Smoking

Many still take up the habit despite efforts to discourage individuals from smoking. This, unfortunately, predisposes these individuals to develop long-term complications and life-threatening diseases that are largely preventable if they quit smoking.

Smoking can increase the risk for cardiovascular diseases, which affect the heart and its associated blood vessels, including atherosclerosis. Meanwhile, respiratory diseases affect the respiratory system, including conditions such as emphysema and chronic obstructive pulmonary disease (COPD). The number one cause of death by smoking is cancer, and it has been estimated that one-third of all cancer deaths are attributed to tobacco use. The most common types of cancers include lung, liver and kidney cancer.

Cardiovascular Diseases

Smoking increases the burden of cardiovascular diseases, such as atherosclerosis. This disease refers to the build-up and hardening of plaque made of substances such as cholesterol and calcium in the vascular system. Tobacco use induces and augments the effects of atherosclerosis through two main mechanisms:

• Endothelium damage
• Increased cholesterol levels

Fig. 2 - An artery affected with atherosclerosis

Endothelial dysfunction is known as the key initiator for atherosclerosis pathogenesis. Evidence has shown that the toxins in tobacco smoke can induce endothelial cell apoptosis and necrosis. In addition to this, proteins known as inflammatory cytokines are secreted upon smoke exposure, which augments endothelial damage and dysfunction.

Respiratory Diseases

Respiratory diseases, or pulmonary diseases, detrimentally affect lung function. This includes COPD, which refers to conditions that make it difficult to break as respiratory structures have been damaged or are dysfunctional. One such COPD is emphysema. This condition occurs when your alveoli, the air sacs of the lungs, become destroyed and permanently enlarged. As a result, the gaseous exchange of oxygen and carbon dioxide in the alveoli is dramatically reduced. In addition to this, cigarette smoke triggers the hypersecretion of mucus, which exacerbates lung obstruction.

Fig. 3 - An ectopic pregnancy in the fallopian tubes

The clinical manifestations of emphysema include:

• Chronic cough
• Excessive mucus secretion
• Shortness of breath

Cancer

Carcinogens, which are agents capable of promoting cancer development, are abundantly present in tobacco smoke, and they include aldehydes, aromatic amines and benzene. Tobacco smoke can contain over 7000 chemicals, of which there are 73 known carcinogens, meaning each puff delivers a cocktail of harmful substances. This can lead to cancers in different organs, most commonly the lungs in chronic smokers.

One of the known mechanisms concerning how tobacco smoke promotes cancer development is through the production of molecules called epoxides, an extremely toxic substance. These epoxides can interact covalently with DNA, bind to DNA and cause DNA replication errors due to complementary base pairing complications. Changes to the nucleotide sequence of DNA are called mutations, and if these mutations occur in oncogenes, cell growth and proliferation can become uncontrolled and lead to tumour development.