Tobacco abuse, most commonly by smoking cigarettes, is a legal drug habit of many throughout the world. It is a significant risk factor for many malignancies, respiratory and cardiovascular diseases and is a major cause of premature mortality throughout the world.
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Epidemiology
It has been estimated by the World Health Organization (WHO) that approximately 7 million people die per year due to personal tobacco use, with a further 1.2 million dying from exposure to second-hand smoke 1. Smoking was estimated in 2015 to be directly responsible for 11.5% of global mortality 10.
In 2015, a large systematic review found that 25% of men and 5.4% of women in the world smoked tobacco daily 10.
Smoking-related disease
Tobacco smoking markedly increases the risk of developing many diseases 2-7. It is a major risk factor for malignancy with a good correlation with an individual's pack-year history 1.
- malignancy: commonest histological type is adenocarcinoma
- lung cancer: all histological forms
- urothelial carcinoma: renal pelvis, ureter, bladder
- head and neck malignancy
- esophageal carcinoma
- hepatocellular carcinoma
- pancreatic adenocarcinoma
- respiratory disease
- asthma
- chronic obstructive pulmonary disease (COPD)
- constrictive bronchiolitis
- respiratory bronchiolitis (RB)
- respiratory bronchiolitis-interstitial lung disease (RB-ILD)
- desquamative interstitial pneumonia (DIP)
- pulmonary Langerhans cell histiocytosis (PLCH)
- idiopathic pulmonary fibrosis-usual interstitial pneumonia
- combined pulmonary fibrosis and emphysema (CPFE)
- acute eosinophilic pneumonia (AEP)
- rheumatoid-arthritis-associated interstitial lung disease (RA-ILD)
- diffuse alveolar hemorrhage (DAH) in Goodpasture syndrome
- pulmonary alveolar proteinosis
- COVID-19
- cardiovascular disease 5
- musculoskeletal
- fractures: smoking impairs bone healing 11,12
- osteoporosis
- autoimmune
- ocular
Diseases for which smoking decreases risk
Pathology
The chemical analysis of tobacco smoke has been intensively studied for more than a century, over which time more than 7,000 different substances have been found in the fumes. The International Agency for Research on Cancer (IARC), of the World Health Organization (WHO), has designated over fifty of these compounds as carcinogens. Toxic compounds found in the smoke include carbon monoxide, benzene, formaldehyde, polycyclic aromatic hydrocarbons, hydrogen cyanide, elemental lead and nitrosamines 1.
However, it is nicotine, an alkaloid compound found in tobacco, which forms almost 95% of the chemical composition of the smoke, that is the primary driver for the addictive nature of tobacco usage 1. Interestingly there is no conclusive evidence that nicotine itself is a carcinogen 14.
Methods of tobacco administration
Although the smoking of cigarettes is far and away the most prevalent form, tobacco is self-administered via a broad range of other methods including:
- smoking
- predominantly cigarettes, including bidis, krekets, water pipes
- pipes
- cigars
- non-smoking forms
- electronic cigarettes (a.k.a. e-cigarettes/vaping)
- snuff
- wet (snus)
- dry
- chewing loose leaf
