Tobacco

The percentage of people in the US who smoke cigarettes has declined since 1964, when the Surgeon General first publicized the link between smoking and ill health. Nevertheless, 14% of adults (34.1 million) in the US still smoke.

Smoking is more prevalent among the following groups:

Smoking is less common among Hispanics and least common among Asian American women.

Nearly all smokers start before the age of 18, making tobacco use a pediatric disorder. Each day, about 1600 youth under age 18 smoke their first cigarette, and nearly 200 youth become daily cigarette smokers. Major risk factors for childhood initiation of smoking include smoking among family members and peers as well as exposure to tobacco advertising and marketing in print, online, and at the point of sale in stores, along with tobacco use scenes in movies and video games.

Cigar and pipe smoking are less common in the US. In 2019, an estimated 8.7 million people aged 18 or older (3.6%) were cigar smokers and 2.4 million (1%) were pipe, water pipe, or hookah smokers. These percentages have remained relatively stable over the past 15 years. Health harms of pipe and cigar smoking include cardiovascular disease; COPD Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease (COPD) is airflow limitation caused by an inflammatory response to inhaled toxins, often cigarette smoke. Alpha-1 antitrypsin deficiency and various occupational... read more ; cancers of the oral cavity Overview of Head and Neck Tumors Head and neck cancer develops in almost 65,000 people in the United States each year. Excluding skin and thyroid cancers, > 90% of head and neck cancers are squamous cell (epidermoid) carcinomas... read more , lung Lung Carcinoma Lung carcinoma is the leading cause of cancer-related death in men and women worldwide. About 85% of cases are related to cigarette smoking. Symptoms can include cough, chest discomfort or pain... read more , larynx Laryngeal Cancer Ninety percent of laryngeal cancer is squamous cell carcinoma. Smoking, excessive alcohol use, lower socioeconomic status, and being male and > 60 years increase risk. Early diagnosis is... read more , esophagus Esophageal Cancer The most common malignant tumor in the proximal two thirds of the esophagus is squamous cell carcinoma; adenocarcinoma is the most common in the distal one third. Symptoms are progressive dysphagia... read more , colon Colorectal Cancer Colorectal cancer is extremely common. Symptoms include blood in the stool and change in bowel habits. Screening using one of several methods is recommended for appropriate populations. Diagnosis... read more , and pancreas Pancreatic Cancer Pancreatic cancer, primarily ductal adenocarcinoma, accounts for an estimated 57,600 cases and 47,050 deaths in the US annually ( 1). Symptoms include weight loss, abdominal pain, and jaundice... read more ; and periodontal disease Periodontitis Periodontitis is a chronic inflammatory oral disease that progressively destroys the tooth-supporting apparatus. It usually manifests as a worsening of gingivitis and then, if untreated, with... read more and tooth loss.

E-cigarettes Vaping Vaping refers to the inhalation of volatilized liquid (vapor) produced by battery-powered devices. The vapor is primarily water, which is the vehicle for a variety of pharmacologically active... read more or vape pens are devices consisting of a battery and a cartridge containing an atomizer to heat a solution with propylene glycol, glycerol, and usually but not always nicotine. While there is no combustion involved in using e-cigarettes, the aerosol emitted from the device is more than water vapor. In addition to often containing nicotine, e-cigarette aerosol has ultrafine particles, which can be inhaled deeply into the lungs; flavoring such as diacetyl, a chemical linked to serious lung disease; volatile organic compounds; cancer-causing chemicals; and heavy metals (eg, nickel, tin, and lead), though all at lower levels than in combusted tobacco smoke. While the long-term effects of inhaling e-cigarette aerosol are not clearly known, it is reasonable to speculate that they are likely to be less detrimental than the well-known adverse effects of smoking combustible cigarettes. For people who use e-cigarettes and continue to smoke, a common practice of dual users, the health benefits of e-cigarette use are unproven. The effects of maternal e-cigarette use on fetal development are unknown, as are the long-term effects of e-cigarette use on the developing adolescent brain. E-cigarette use among high school students exceeds combustible tobacco use (in 2019, 27.5% use e-cigarettes vs 7.6% cigars and 5.8% combustible cigarettes), according to the Centers for Disease Control and Prevention (CDC). The long-term risks of e-cigarette smoking, a relatively new phenomenon, are unknown. (See also information about e-cigarettes from the The National Academies of Sciences, Engineering, and Medicine [Health and Medicine Division]: Public health consequences of e-cigarettes.)

E-cigarette and Vaping product-use Associated Lung Injury (EVALI) is a term used by the CDC to describe a multi-state outbreak of severe lung illness first identified in August 2019 and associated with using e-cigarette and vaping products. The clinical presentation is a diagnosis of exclusion that includes respiratory symptoms (eg, cough, chest pain, shortness of breath), gastrointestinal symptoms (eg, abdominal pain, nausea, vomiting, diarrhea), nonspecific constitutional symptoms (eg, fever, chills, weight loss), reduced blood oxygen levels, elevated white blood cell counts, and injuries resembling those caused by exposures to toxic chemical fumes, poisonous gases, and toxic agents. According to the CDC, as of February 2020, there have been over 2800 hospitalizations and 68 deaths nationally due to EVALI. The CDC’s guidelines point largely to vaping of tetrahydrocannabinol (THC) liquid as the cause, and in particular THC liquids cut with Vitamin E acetate. The CDC encourages clinicians to continue to report possible EVALI cases to their local or state health department for further investigation (see CDC: Outbreak of Lung Injury Associated with E-cigarette Use, or Vaping). If EVALI is suspected, the clinician should obtain a detailed history of substances used, sources of products, duration and frequency of use, and devices used and how those devices were used.

Smokeless tobacco (chewing tobacco and snuff) is used by about 2.4% of people ≥ 18 years of age and about 4.8% of high school students. Toxicity of smokeless tobacco varies by brand. Harms include cardiovascular disease, oral disorders (eg, cancers, gum recession, gingivitis, periodontitis and its consequences), and teratogenicity.

Inadvertent oral exposure to tobacco is uncommon but may cause serious toxicity. Young children occasionally ingest cigarettes from unguarded packs, cigarette butts from ashtrays, e-cigarette liquid, or nicotine gum. In 2019, 5356 cases of potentially toxic exposure to e-cigarettes and liquid nicotine products were reported to the American Association of Poison Control Centers (AAPCC).

Cutaneous exposure to tobacco can be toxic. Tobacco harvesters and processors who handle raw tobacco (especially if wet) without protection may absorb nicotine through the skin and develop symptoms of nicotine toxicity, a syndrome termed green tobacco sickness.

Passive exposure to tobacco smoke Secondhand smoke Tobacco use is a major individual and public health problem. Dependence develops rapidly. Major consequences include premature death and morbidity caused by cardiovascular disease, lung and... read more (second-hand smoke) occurs when people inhale smoke from a burning cigarette or the smoke exhaled by a nearby smoker. The amount inhaled (and thus its effects) varies with the proximity and duration of exposure as well as the environment (eg, closed space) and ventilation.

Smoking harms nearly every organ in the body. Smoking is the leading cause of preventable mortality in the US and globally. In the US, smoking accounts for an estimated 520,000 deaths/year, or about 20% of all deaths. About two in three long-term smokers die prematurely of a disease directly caused by smoking, losing 10 to 14 years of life (7 minute/cigarette) on average.

The major chronic effects are an increased likelihood of the following:

Coronary artery disease accounts for about 30 to 40% of all tobacco-related deaths. Risk of myocardial infarction is increased by > 200% if smoking < 1 pack/day and risk of cardiovascular mortality is increased by > 50% over a 35-year period. Mechanisms include endothelial cell damage, transient increases in blood pressure and heart rate, induction of a prothrombotic state, and adverse effects on serum lipids.

Lung cancer accounts for about 15 to 20% of tobacco-related deaths. Smoking tobacco is the most common cause of lung cancer in North America and Europe, and accounts for more than 87% of lung cancer deaths. Inhaled carcinogens are directly exposed to lung tissue.

COPD accounts for roughly 20% of tobacco-related deaths. Tobacco is the most common cause of COPD and accounts for 61% of all pulmonary disease deaths. Smoking impairs local respiratory tract defense mechanisms and, particularly in genetically susceptible people, tends to accelerate decline in pulmonary functions. Coughing and dyspnea on exertion are common.

Less common yet serious smoking-related disorders include age-related macular degeneration, noncardiac vascular diseases (eg, stroke, aortic aneurysm), other cancers (eg, bladder, cervical, colorectal, esophageal, kidney, laryngeal, liver, oropharyngeal, pancreatic, stomach, throat, acute myeloid leukemia), diabetes, pneumonia, rheumatoid arthritis, and tuberculosis.

In addition, smoking is a risk factor for other conditions that convey significant morbidity and disability, such as frequent upper respiratory infections Overview of Viral Respiratory Infections Viral infections commonly affect the upper or lower respiratory tract. Although respiratory infections can be classified by the causative virus (eg, influenza), they are generally classified... read more , asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more , cataracts Cataract A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is... read more , infertility Overview of Infertility Infertility is usually defined as the inability to conceive after 1 year of regular, unprotected sexual intercourse. Infertility is defined as a disease by the World Health Organization (WHO)... read more , erectile dysfunction Erectile Dysfunction Erectile dysfunction is the inability to attain or sustain an erection satisfactory for sexual intercourse. Most erectile dysfunction is related to vascular, neurologic, psychologic, and hormonal... read more , premature menopause Menopause Menopause is the permanent cessation of menses (amenorrhea) due to loss of ovarian follicular function. Clinical manifestations may include hot flushes, night sweats, sleep disruption, and genitourinary... read more , peptic ulcer disease Peptic Ulcer Disease A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more , osteoporosis Osteoporosis Osteoporosis is a progressive metabolic bone disease that decreases bone mineral density (bone mass per unit volume), with deterioration of bone structure. Skeletal weakness leads to fractures... read more , hip fractures Hip Fractures Hip fractures may occur in the head, neck, or area between or below the trochanters (prominences) of the femur. These fractures are most common among older patients, particularly those with... read more , and periodontitis Periodontitis Periodontitis is a chronic inflammatory oral disease that progressively destroys the tooth-supporting apparatus. It usually manifests as a worsening of gingivitis and then, if untreated, with... read more .

Secondhand smoke is tobacco smoke that is exhaled by a smoker or given off from the end of a lit cigarette. Secondhand smoke is linked to the same neoplastic, respiratory, and cardiovascular diseases that threaten active smokers. The risk of illness is related to dose. For example, between spouses, average risk is increased by about 20% for lung cancer and by about 20 to 30% for coronary artery disease.

Children exposed to cigarette smoke lose more school days because of illness than nonexposed children. Treating children for smoking-related illnesses is estimated to cost $4.6 billion/year.

Overall, secondhand smoke is estimated to cause 50,000 to 60,000 deaths each year in the US (between 2% and 3% of all deaths), with lost productivity costs due to premature deaths from secondhand smoke exposure estimated to be $5.6 billion per year. These findings have led states and municipalities across the US to ban smoking within workplaces in an effort to protect the health of workers and others from the substantive risks of environmental tobacco smoke. In 2000, no state or the District of Columbia had a comprehensive indoor smoke-free ordinance in effect, this increased to 26 by the end of 2010, and one additional state was added by the end of 2015. In some states without statewide comprehensive smoke-free laws, substantial progress has been made at the local level in adopting comprehensive smoke-free laws. However, 8 states without statewide comprehensive smoke-free laws (Connecticut, Florida, New Hampshire, North Carolina, Oklahoma, Pennsylvania, Tennessee, and Virginia) have preemption statutes that prohibit adoption of local smoke-free laws.

Smoking during pregnancy increases the risk of spontaneous abortion, ectopic pregnancy, preterm birth, and congenital defects ( see Social and Illicit Drugs During Pregnancy Social and Illicit Drugs During Pregnancy Drugs are used in over half of all pregnancies, and prevalence of use is increasing. The most commonly used drugs include antiemetics, antacids, antihistamines, analgesics, antimicrobials, diuretics... read more ). Infants born of mothers who smoke tend to have a lower birth weight and are at increased risk of

Indirect effects of smoking can be serious.

Smoking-related fires occur in about 7600 residential buildings in the US each year, according to the Federal Emergency Management Agency (FEMA). These fires cause about 365 deaths, 925 injuries, and $326 million in property loss annually. Such fires are the leading cause of deaths resulting from unintentional fires in the US.

Drug interactions with smoking are common. The effects are largely due to induction of metabolic enzymes in the liver by tar byproducts of smoking. Nicotine does not similarly induce metabolic enzymes, and thus drug-induction effects do not occur with nicotine replacement therapy or e-cigarettes. Levels and sometimes clinical effects of the following drugs are decreased by chronic smoking, primarily by induction of CYP2A6 enzymes:

Two exceptions are benzodiazepines, for which drug sedation effects are decreased likely due to the stimulating effects of nicotine, and beta-blockers, with reduced blood pressure and heart rate control possibly caused by nicotine-mediated sympathetic activation.

Nicotine slightly increases heart rate, blood pressure, and respiratory rate. Smokers may feel increased energy and arousal, increased ability to concentrate, decreased tension and anxiety, and a sense of pleasure and reward. Nausea is common on a person's first exposure to nicotine. Nicotine reduces appetite and can be a behavioral substitute for eating.

With combustible tobacco, exercise tolerance tends to decrease because of respiratory tract irritation. Low-grade carbon monoxide toxicity can also limit exercise tolerance, but this is probably only a factor in elite athletes.

Acute nicotine poisoning is usually caused by oral (eg, children eating a cigarette or nicotine gum or ingesting e-liquid) or dermal (eg, handling raw tobacco products) exposure, rather than smoking.

Mild nicotine toxicity, as is common with green tobacco sickness and minor ingestions by children (eg, < 1 cigarette or 3 butts), typically manifests with nausea, vomiting, headache, and weakness. Symptoms spontaneously resolve, usually in 1 to 2 hours after ingestion if poisoning is mild; however, symptoms can persist for 24 hours if poisoning is severe.

Severe nicotine poisoning causes a cholinergic toxidrome with nausea, vomiting, salivation, lacrimation, diarrhea, urination, fasciculations, and muscle weakness. Patients usually have crampy abdominal pain and, if poisoning is very severe, arrhythmias, hypotension, seizures, and coma. The fatal dose of nicotine is about 60 mg in adult nonsmokers, 120 mg in adult smokers, and as little as 10 mg in young children. Each cigarette contains about 8 mg of nicotine (only about 1 mg is absorbed by smoking). However, the amount ingested by children is usually difficult to ascertain by history because ingestion is rarely observed; any ingestion should be considered potentially dangerous.

Findings due to smoking itself include yellow stains of teeth and fingers, and in comparison to age-matched controls, weight is slightly lower (≤ 5 kg difference), skin is drier and more wrinkled, and hair is thinner.

Other symptoms are those of smoking-related lung and cardiovascular disease. Chronic cough and dyspnea on exertion are common. Circulatory and respiratory impairments decrease exercise tolerance, often resulting in a more sedentary lifestyle and thus further lowering of exercise tolerance.

Smoking cessation often causes intense nicotine withdrawal symptoms Nicotine Withdrawal Most smokers want to quit and have tried doing so with limited success. Effective interventions include cessation counseling and drug treatment, such as varenicline, bupropion, or a nicotine... read more , primarily a craving for cigarettes but also other symptoms (eg, anxiety, difficulty concentrating, sleep disruption, depression) and eventual weight gain.