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16.6: Smoking and Health - Biology

16.6: Smoking and Health - Biology



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Sure Death

The anti-smoking cartoon in Figure (PageIndex{1}) clearly makes the point that smoking causes death. The cartoon is not using hyperbole, because smoking actually is deadly. It causes about six million deaths each year and is the single greatest cause of preventable death worldwide. As many as half of all people who smoke tobacco die from it. As a result of smoking’s deadly effects, the life expectancy of long-term smokers is significantly less than that of non-smokers. In fact, long-term smokers can expect their lifespan to be reduced by as much as 18 years, and they are three times as likely to die before the age of 70 as non-smokers.

Why Is Smoking Deadly?

As shown in Figure (PageIndex{2}), tobacco smoking has adverse effects on just about every bodily system and organ. The detrimental health effects of smoking depend on the number of years that a person smokes and how much the person smokes. Contrary to popular belief, all forms of tobacco smoke — including smoke from cigars and tobacco pipes — have similar health risks as those of cigarette smoke. Smokeless tobacco may be less of a danger to the lungs and heart, but it too has serious health effects. It significantly increases the risk of cancers of the mouth and throat, among other health problems.

Even non-smokers may not be spared the deadly risks of tobacco smoke. If you spend time around smokers either at home or on the job, then you are at risk of the dangers of secondhand smoke. Secondhand smoke enters the air directly from burning cigarettes (and cigars and pipes) and indirectly from the lungs of smokers. This smoke may linger in indoor air for hours and increase the risk of a wide range of adverse health effects. For example, non-smokers who are exposed to secondhand smoke may have as much as a 30 percent increase in their risk of lung cancer and heart disease. The 2014 U.S. Surgeon General’s Report concluded that there is no established risk-free level of exposure to secondhand smoke.

Tobacco contains nicotine, which is a psychoactive drug. Although nicotine in tobacco smoke does not directly cause cancer or most of the other health risks of smoking, it is a highly addictive drug. In fact, nicotine is even more addictive than cocaine or heroin. The addictive nature of nicotine explains why it is so difficult for smokers to quit the habit even when they know the health risks and really want to stop smoking. The good news is that if someone does stop smoking, his or her risks of smoking-related diseases and death soon start to fall. For example, by one year after quitting, the risk of heart disease drops to only half of that of a continuing smoker.

Smoking and Cancer

One of the main health risks of smoking is cancer, particularly cancer of the lung. Because of the increased risk of lung cancer with smoking, the risk of dying from lung cancer before age 85 is more than 20 times higher for a male smoker than for a male non-smoker. As the rate of smoking increases, so does the rate of lung cancer deaths, although the effects of smoking on lung cancer deaths can take up to 20 years to manifest themselves, as shown in Figure (PageIndex{3}).

Besides lung cancer, several other forms of cancer are also significantly more likely in smokers than non-smokers, including cancers of the kidney, larynx, mouth, lip, tongue, throat, bladder, esophagus, pancreas, and stomach. Unfortunately, many of these cancers have extremely low cure rates.

When you consider the composition of tobacco smoke, it’s not surprising that it increases the risk of cancer. Tobacco smoke contains dozens of chemicals that have been proven to be carcinogens or causes of cancer. Many of these chemicals bind to DNA in a smoker’s cells and may either kill the cells or cause mutations. If the mutations inhibit programmed cell death, the cells can survive to become cancer cells. Some of the most potent carcinogens in tobacco smoke include benzopyrene, acrolein, and nitrosamines. Other carcinogens in tobacco smoke are radioactive isotopes, including lead-210 and polonium-210.

Respiratory Effects of Smoking

Long-term exposure to the compounds found in cigarette smoke, such as carbon monoxide and cyanide, is thought to be responsible for much of the lung damage caused by smoking. These chemicals reduce the elasticity of alveoli, leading to chronic obstructive pulmonary disease (COPD). COPD is a permanent, incurable, and often fatal reduction in the capacity of the lungs, reducing the ability of the lungs to fully exhale air. The chronic inflammation that is also present in COPD is exacerbated by the tobacco smoke carcinogen acrolein and its derivatives. COPD is almost completely preventable simply by not smoking and by also avoiding secondhand smoke.

Cardiovascular Effects of Smoking

Inhalation of tobacco smoke causes several immediate responses in the heart and blood vessels. Within one minute of inhalation of smoke, the heart rate begins to rise, increasing by as much as 30 percent during the first 10 minutes of smoking. Carbon monoxide in tobacco smoke binds with hemoglobin in red blood cells, thereby reducing the blood’s ability to carry oxygen. Hemoglobin bound to carbon monoxide forms such a stable complex that it may result in a permanent loss of red blood cell function. Several other chemicals in tobacco smoke lead to the narrowing and weakening of blood vessels and an increase in substances that contribute to blood clotting. These changes increase blood pressure and the chances of a blood clot forming and blocking a vessel, thereby elevating the risk of heart attack and stroke. A recent study found that smokers are five times more likely than non-smokers to have a heart attack before the age of 40.

Smoking has also been shown to have a negative impact on the levels of blood lipids. Total cholesterol levels tend to be higher in smokers than non-smokers. Ratios of “good” cholesterol to “bad” cholesterol tend to be lower in smokers than in non-smokers.

Additional Adverse Health Effects of Smoking

A wide diversity of additional adverse health effects are attributable to smoking. Here are just a few of them:

  • Smokers are at a significantly increased risk of developing chronic kidney disease (in addition to kidney cancer). For example, smoking hastens the progression of kidney damage in people with diabetes.
  • People who smoke, especially the elderly, have a greater risk of influenza and other infectious diseases than non-smokers. Smoking more than 20 cigarettes a day has been found to increase the risk of infectious diseases by as much as four times the risk in non-smokers. These effects occur because of damage to both the respiratory system and the immune system.
  • In addition to oral cancer, smoking causes other oral problems including periodontitis (gum disease). Roughly half of the cases of gum inflammation are attributable to current or former smoking. Such inflammation increases the risk of tooth loss, which is also higher in smokers than non-smokers. In addition, smoking stains the teeth and causes halitosis (bad breath).
  • Smoking is a key cause of erectile dysfunction (ED), probably because it leads to narrowing of arteries in the penis as it does elsewhere in the body. The incidence of ED is about 85 percent higher in males who smoke than it is in non-smokers.
  • Smoking also has adverse effects on the female reproductive system, potentially causing infertility, in part because it interferes with the body’s ability to produce estrogen. Female smokers are about 60 percent more likely to be infertile than non-smokers. Pregnant women who smoke or are exposed to secondhand smoke have a higher risk of miscarriages and low-birth-weight infants.
  • Certain therapeutic drugs, including some antidepressants and anticonvulsants, are less effective in smokers than in non-smokers. This occurs because smoking increases levels of liver enzymes that break down the drugs.
  • Smoking causes an estimated 10 percent of all deaths due to fires worldwide. Smokers are also at greater risk of dying in motor vehicle crashes and other accidents.
  • Smoking leads to an increased risk of bone fractures, especially of the hip. It also leads to slower wound healing after surgery and an increased rate of postoperative complications.

Feature: Human Biology in the News

The item in Figure (PageIndex{4}) looks like a regular cigarette, but it’s actually an electronic cigarette or e-cigarette. E-cigarettes are battery-powered devices that change flavored liquids and nicotine into a vapor that is inhaled by the user. E-cigarettes are often promoted as being safer than traditional tobacco products and their use is touted as a good way to quit smoking. They are often not banned in smoke-free areas where it is illegal to smoke tobacco cigarettes.

A study completed in 2015 by researchers at the Harvard School of Public Health and widely reported in the mass media found that e-cigarettes may in fact be very harmful to the user’s health. E-cigarettes contain nicotine and cancer-causing chemicals such as formaldehyde. According to the study, about three-quarters of flavored e-cigarettes also contain a chemical named diacetyl that causes an incurable and potentially fatal disorder of the lungs, commonly called “popcorn lung” (bronchiolitis obliterans). In this disorder, the bronchioles compress and narrow due to the formation of scar tissue. This greatly diminishes the breathing capacity of people with the disorder. Popcorn lung gained its common name in 2004 when it was diagnosed in workers at popcorn factories. The buttery flavoring used in the factories contained diacetyl.

Some manufacturers of e-cigarettes and flavorings advertise that their products are now free of diacetyl. However, because e-cigarettes are not currently regulated by the FDA, there is no way of knowing for sure whether the products are actually safe. Equally disturbing is the appeal of flavored e-cigarettes to teens and the attempts of producers to specifically market their products to this age group. Flavors such as “cotton candy,” “Katy Perry’s cherry,” and “alien blood” are obviously marketed to youth. Not surprisingly, the use of e-cigarettes is on the rise in middle and high school students, who are more likely to use them than regular cigarettes. Public health officials fear that e-cigarettes will be a gateway for teens to move on to smoking tobacco cigarettes. Some states have recently passed laws prohibiting minors from buying e-cigarettes. As more questions are raised about their potential negative health effects, it is likely that more laws will be passed to regulate them. Watch the news for updates on this issue.

Review

  1. What percentage of people who smoke are likely to die from it?
  2. Contrast the life expectancy of long-term smokers and non-smokers.
  3. What factors related to smoking determine how smoking affects a smoker’s health?
  4. What are the two sources of secondhand cigarette smoke? How does exposure to secondhand smoke affect non-smokers?
  5. Why is it so difficult for smokers to quit the habit? How is their health likely to be affected by quitting?
  6. List five types of cancer that are significantly more likely in smokers than non-smokers.
  7. Why does smoking cause cancer?
  8. Explain how smoking causes COPD.
  9. Identify some of the adverse effects of smoking on the cardiovascular system.
  10. Give three examples of additional adverse health effects that are more likely with smoking.
  11. Do you think e-cigarettes can be addictive? Explain your reasoning.
  12. People who smoke are more likely to get ___________ than people who do not smoke.

    A. lung cancer

    B. influenza

    C. kidney disease

    D. All of the above

  13. Name three toxic chemicals present in tobacco smoke.

  14. True or False. Nicotine is more addictive than heroin.

  15. True or False. Smoking has many negative effects on the respiratory and cardiovascular systems, but not on other systems of the body.


Health Risks of Smoking Tobacco

Tobacco use remains the leading preventable cause of death in the US, accounting for about 1 in 5 deaths each year.

On average, people who smoke die about 10 years earlier than people who have never smoked.

Most people know smoking can cause cancer. But it can also cause a number of other diseases and can damage nearly every organ in the body, including the lungs, heart, blood vessels, reproductive organs, mouth, skin, eyes, and bones.


Harms of Cigarette Smoking and Health Benefits of Quitting

Tobacco smoke contains many chemicals that are harmful to both smokers and nonsmokers. Breathing even a little tobacco smoke can be harmful (1-4).

Of the more than 7,000 chemicals in tobacco smoke, at least 250 are known to be harmful, including hydrogen cyanide, carbon monoxide, and ammonia (1, 2, 5).

Among the 250 known harmful chemicals in tobacco smoke, at least 69 can cause cancer. These cancer-causing chemicals include the following (1, 2, 5):

  • Acetaldehyde
  • Aromatic amines
  • Beryllium (a toxic metal)
  • 1,3–Butadiene (a hazardous gas) (a toxic metal)
  • Chromium (a metallic element)
  • Cumene
  • Nickel (a metallic element)
  • Polonium-210 (a radioactive chemical element) (PAHs)

What are some of the health problems caused by cigarette smoking?

Smoking is the leading cause of premature, preventable death in this country. Cigarette smoking and exposure to tobacco smoke cause about 480,000 premature deaths each year in the United States (1). Of those premature deaths, about 36% are from cancer, 39% are from heart disease and stroke, and 24% are from lung disease (1). Mortality rates among smokers are about three times higher than among people who have never smoked (6, 7).

Smoking harms nearly every bodily organ and organ system in the body and diminishes a person’s overall health. Smoking causes cancers of the lung, esophagus, larynx, mouth, throat, kidney, bladder, liver, pancreas, stomach, cervix, colon, and rectum, as well as acute myeloid leukemia (1–3).

Smoking also causes heart disease, stroke, aortic aneurysm (a balloon-like bulge in an artery in the chest), chronic obstructive pulmonary disease (COPD) (chronic bronchitis and emphysema), diabetes, osteoporosis, rheumatoid arthritis, age-related macular degeneration, and cataracts, and worsens asthma symptoms in adults. Smokers are at higher risk of developing pneumonia, tuberculosis, and other airway infections (1–3). In addition, smoking causes inflammation and impairs immune function (1).

Since the 1960s, a smoker’s risk of developing lung cancer or COPD has actually increased compared with nonsmokers, even though the number of cigarettes consumed per smoker has decreased (1). There have also been changes over time in the type of lung cancer smokers develop – a decline in squamous cell carcinomas but a dramatic increase in adenocarcinomas. Both of these shifts may be due to changes in cigarette design and composition, in how tobacco leaves are cured, and in how deeply smokers inhale cigarette smoke and the toxicants it contains (1, 8).

Smoking makes it harder for a woman to get pregnant. A pregnant smoker is at higher risk of miscarriage, having an ectopic pregnancy, having her baby born too early and with an abnormally low birth weight, and having her baby born with a cleft lip and/or cleft palate (1). A woman who smokes during or after pregnancy increases her infant’s risk of death from Sudden Infant Death Syndrome (SIDS) (2, 3). Men who smoke are at greater risk of erectile dysfunction (1, 9).

The longer a smoker’s duration of smoking, the greater their likelihood of experiencing harm from smoking, including earlier death (7). But regardless of their age, smokers can substantially reduce their risk of disease, including cancer, by quitting.

What are the risks of tobacco smoke to nonsmokers?

Secondhand smoke (also called environmental tobacco smoke, involuntary smoking, and passive smoking) is the combination of “sidestream” smoke (the smoke given off by a burning tobacco product) and “mainstream” smoke (the smoke exhaled by a smoker) (4, 5, 10, 11).

The U.S. Environmental Protection Agency, the U.S. National Toxicology Program, the U.S. Surgeon General, and the International Agency for Research on Cancer have classified secondhand smoke as a known human carcinogen (cancer-causing agent) (5, 11, 12). Inhaling secondhand smoke causes lung cancer in nonsmoking adults (1, 2, 4). Approximately 7,300 lung cancer deaths occur each year among adult nonsmokers in the United States as a result of exposure to secondhand smoke (1). The U.S. Surgeon General estimates that living with a smoker increases a nonsmoker’s chances of developing lung cancer by 20 to 30% (4).

Secondhand smoke causes disease and premature death in nonsmoking adults and children (2, 4). Exposure to secondhand smoke irritates the airways and has immediate harmful effects on a person’s heart and blood vessels. It increases the risk of heart disease by an estimated 25 to 30% (4). In the United States, exposure to secondhand smoke is estimated to cause about 34,000 deaths from heart disease each year (1). Exposure to secondhand smoke also increases the risk of stroke by 20 to 30% (1). Pregnant women exposed to secondhand smoke are at increased risk of having a baby with a small reduction in birth weight (1).

Children exposed to secondhand smoke are at an increased risk of SIDS, ear infections, colds, pneumonia, and bronchitis. Secondhand smoke exposure can also increase the frequency and severity of asthma symptoms among children who have asthma. Being exposed to secondhand smoke slows the growth of children’s lungs and can cause them to cough, wheeze, and feel breathless (2, 4).

Smoking is highly addictive. Nicotine is the drug primarily responsible for a person’s addiction to tobacco products, including cigarettes. The addiction to cigarettes and other tobacco products that nicotine causes is similar to the addiction produced by using drugs such as heroin and cocaine (13). Nicotine is present naturally in the tobacco plant. But tobacco companies intentionally design cigarettes to have enough nicotine to create and sustain addiction.

The amount of nicotine that gets into the body is determined by the way a person smokes a tobacco product and by the nicotine content and design of the product. Nicotine is absorbed into the bloodstream through the lining of the mouth and the lungs and travels to the brain in a matter of seconds. Taking more frequent and deeper puffs of tobacco smoke increases the amount of nicotine absorbed by the body.

Are other tobacco products, such as smokeless tobacco or pipe tobacco, harmful and addictive?

Yes. All forms of tobacco are harmful and addictive (4, 11). There is no safe tobacco product.

In addition to cigarettes, other forms of tobacco include smokeless tobacco, cigars, pipes, hookahs (waterpipes), bidis, and kreteks.

  • Smokeless tobacco: Smokeless tobacco is a type of tobacco that is not burned. It includes chewing tobacco, oral tobacco, spit or spitting tobacco, dip, chew, snus, dissolvable tobacco, and snuff. Smokeless tobacco causes oral (mouth, tongue, cheek and gum), esophageal, and pancreatic cancers and may also cause gum and heart disease (11, 14).
  • Cigars: These include premium cigars, little filtered cigars (LFCs), and cigarillos. LFCs resemble cigarettes, but both LFCs and cigarillos may have added flavors to increase appeal to youth and young adults (15, 16). Most cigars are composed primarily of a single type of tobacco (air-cured and fermented), and have a tobacco leaf wrapper. Studies have found that cigar smoke contains higher levels of toxic chemicals than cigarette smoke, although unlike cigarette smoke, cigar smoke is often not inhaled (11). Cigar smoking causes cancer of the oral cavity, larynx, esophagus, and lung. It may also cause cancer of the pancreas. Moreover, daily cigar smokers, particularly those who inhale, are at increased risk for developing heart disease and other types of lung disease.
  • Pipes: In pipe smoking, the tobacco is placed in a bowl that is connected to a stem with a mouthpiece at the other end. The smoke is usually not inhaled. Pipe smoking causes lung cancer and increases the risk of cancers of the mouth, throat, larynx, and esophagus (11, 17, 18).
  • Hookah or waterpipe (other names include argileh, ghelyoon, hubble bubble, shisha, boory, goza, and narghile): A hookah is a device used to smoke tobacco (often heavily flavored) by passing the smoke through a partially filled water bowl before being inhaled by the smoker. Although some people think hookah smoking is less harmful and addictive than cigarette smoking (19), research shows that hookah smoke is at least as toxic as cigarette smoke (20–22).
  • Bidis: A bidi is a flavored cigarette made by rolling tobacco in a dried leaf from the tendu tree, which is native to India. Bidi use is associated with heart attacks and cancers of the mouth, throat, larynx, esophagus, and lung (11, 23).
  • Kreteks: A kretek is a cigarette made with a mixture of tobacco and cloves. Smoking kreteks is associated with lung cancer and other lung diseases (11, 23).

Is it harmful to smoke just a few cigarettes a day?

There is no safe level of smoking. Smoking even just one cigarette per day over a lifetime can cause smoking-related cancers (lung, bladder, and pancreas) and premature death (24, 25).

What are the immediate health benefits of quitting smoking?

The immediate health benefits of quitting smoking are substantial:

    and blood pressure, which are abnormally high while smoking, begin to return to normal.
  • Within a few hours, the level of carbon monoxide in the blood begins to decline. (Carbon monoxide reduces the blood’s ability to carry oxygen.)
  • Within a few weeks, people who quit smoking have improved circulation, produce less phlegm, and don’t cough or wheeze as often.
  • Within several months of quitting, people can expect substantial improvements in lung function (26).
  • Within a few years of quitting, people will have lower risks of cancer, heart disease, and other chronic diseases than if they had continued to smoke.

What are the long-term health benefits of quitting smoking?

Quitting smoking reduces the risk of cancer and many other diseases, such as heart disease and COPD, caused by smoking.

Data from the U.S. National Health Interview Survey show that people who quit smoking, regardless of their age, are less likely to die from smoking-related illness than those who continue to smoke. Smokers who quit before age 40 reduce their chance of dying prematurely from smoking-related diseases by about 90%, and those who quit by age 45-54 reduce their chance of dying prematurely by about two-thirds (6).

Regardless of their age, people who quit smoking have substantial gains in life expectancy, compared with those who continue to smoke. Data from the U.S. National Health Interview Survey also show that those who quit between the ages of 25 and 34 years live about 10 years longer those who quit between ages 35 and 44 live about 9 years longer those who quit between ages 45 and 54 live about 6 years longer and those who quit between ages 55 and 64 live about 4 years longer (6).

Also, a study that followed a large group of people age 70 and older (7) found that even smokers who quit smoking in their 60s had a lower risk of mortality during follow-up than smokers who continued smoking.

Does quitting smoking lower the risk of getting and dying from cancer?

Yes. Quitting smoking reduces the risk of developing and dying from cancer and other diseases caused by smoking. Although it is never too late to benefit from quitting, the benefit is greatest among those who quit at a younger age (3).

The risk of premature death and the chances of developing and dying from a smoking-related cancer depend on many factors, including the number of years a person has smoked, the number of cigarettes smoked per day, and the age at which the person began smoking.

Is it important for someone diagnosed with cancer to quit smoking?

Quitting smoking improves the prognosis of cancer patients. For patients with some cancers, quitting smoking at the time of diagnosis may reduce the risk of dying by 30% to 40% (1). For those having surgery, chemotherapy, or other treatments, quitting smoking helps improve the body’s ability to heal and respond to therapy (1, 3, 27). It also lowers the risk of pneumonia and respiratory failure (1, 3, 28). In addition, quitting smoking may lower the risk that the cancer will recur, that a second cancer will develop, or that the person will die from the cancer or other causes (27, 29–32).

Where can I get help to quit smoking?

NCI and other agencies and organizations can help smokers quit:

  • Visit Smokefree.gov for access to free information and resources, including Create My Quit Plan, smartphone apps, and text message programs
  • Call the NCI Smoking Quitline at 1–877–44U–QUIT (1–877–448–7848) for individualized counseling, printed information, and referrals to other sources.
  • See the NCI fact sheet Where To Get Help When You Decide To Quit Smoking.
Selected References

U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General, 2014. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014.

U.S. Department of Health and Human Services. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2010.

U.S. Department of Health and Human Services. The Health Consequences of Smoking: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004.

U.S. Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006.

National Toxicology Program. Tobacco-Related Exposures. In: Report on Carcinogens. Fourteenth Edition. U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program, 2016.

Jha P, Ramasundarahettige C, Landsman V, et al. 21st-century hazards of smoking and benefits of cessation in the United States. New England Journal of Medicine 2013 368(4):341–350.

Nash SH, Liao LM, Harris TB, Freedman ND. Cigarette smoking and mortality in adults aged 70 years and older: Results from the NIH-AARP cohort. American Journal of Preventive Medicine 2017 52(3):276-283

Hecht SS. Tobacco carcinogens, their biomarkers and tobacco-induced cancer. Nature Reviews. Cancer. 2003 3(10):733-744.

Austoni E, Mirone V, Parazzini F, et al. Smoking as a risk factor for erectile dysfunction: Data from the Andrology Prevention Weeks 2001–2002. A study of the Italian Society of Andrology (S.I.A.). European Urology 2005 48(5):810–818.

National Cancer Institute. Cancer Trends Progress Report: Secondhand Smoke Exposure. National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD, January 2017.

International Agency for Research on Cancer. Tobacco smoking, Second-hand tobacco smoke, and Smokeless tobacco. In: Personal Habits and Indoor Combustions: A Review of Human Carcinogens. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 100E. Lyon, France: International Agency for Research on Cancer 2012. p. 43-318.

U.S. Environmental Protection Agency. Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders. Washington, DC: U.S. Environmental Protection Agency, Office of Health and Environmental Assessment, Office of Research and Development 1992.

Hatsukami DK, Stead LF, Gupta PC. Tobacco addiction. Lancet 2008 371(9629):2027–2038.

Piano MR, Benowitz NL, Fitzgerald GA, et al. Impact of smokeless tobacco products on cardiovascular disease: implications for policy, prevention, and treatment: a policy statement from the American Heart Association. Circulation 2010 122(15):1520-1544. doi: 10.1161/CIR.0b013e3181f432c3.

Villanti AC, Richardson A, Vallone DM, Rath JM. Flavored tobacco product use among U.S. young adults. American Journal of Preventive Medicine 2013 44(4):388-391.

Corey CG, Ambrose BK, Apelberg BJ, King BA. Flavored tobacco product use among middle and high school students--United States, 2014. MMWR. Morbidity and Mortality Weekly Report 2015 64(38):1066-1070.

Henley SJ, Thun MJ, Chao A, Calle EE. Association between exclusive pipe smoking and mortality from cancer and other diseases. Journal of the National Cancer Institute 2004 96(11):853–861.

Wyss A, Hashibe M, Chuang SC, et al. Cigarette, cigar, and pipe smoking and the risk of head and neck cancers: Pooled analysis in the International Head and Neck Cancer Epidemiology Consortium. American Journal of Epidemiology 2013 178(5):679-690.

Smith-Simone S, Maziak W, Ward KD, Eissenberg T. Waterpipe tobacco smoking: Knowledge, attitudes, beliefs, and behavior in two U.S. samples. Nicotine Tobacco Research 2008 10(2):393–398.

Knishkowy B, Amitai Y. Water-pipe (narghile) smoking: An emerging health risk behavior. Pediatrics 2005 116(1):e113‒119.

Cobb C, Ward KD, Maziak W, Shihadeh AL, Eissenberg T. Waterpipe tobacco smoking: An emerging health crisis in the United States. American Journal of Health Behavior 2010 34(3):275–285.

Prignot JJ, Sasco AJ, Poulet E, Gupta PC, Aditama TY. Alternative forms of tobacco use. International Journal of Tuberculosis and Lung Disease 2008 12(7):718–727.

Inoue-Choi M, Liao LM, Reyes-Guzman C, et al. Association of long-term, low-intensity smoking with all-cause and cause-specific mortality in the National Institutes of Health-AARP Diet and Health Study. JAMA Internal Medicine 2017 177(1):87-95.

Inoue-Choi M, Hartge P, Liao LM, Caporaso N, Freedman ND. Association between long-term low-intensity cigarette smoking and incidence of smoking-related cancer in the National Institutes of Health-AARP cohort. International Journal of Cancer 2018 142(2):271-280.

U.S. Department of Health and Human Services. The Health Benefits of Smoking Cessation: A Report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 1990.

McBride CM, Ostroff JS. Teachable moments for promoting smoking cessation: The context of cancer care and survivorship. Cancer Control 2003 10(4):325–333.

Peto R, Darby S, Deo H, et al. Smoking, smoking cessation, and lung cancer in the U.K. since 1950: Combination of national statistics with two case-control studies. British Medical Journal 2000 321(7257):323–329.

Travis LB, Rabkin CS, Brown LM, et al. Cancer survivorship―genetic susceptibility and second primary cancers: Research strategies and recommendations. Journal of the National Cancer Institute 2006 98(1):15–25.

Parsons A, Daley A, Begh R, Aveyard P. Influence of smoking cessation after diagnosis of early stage lung cancer on prognosis: Systematic review of observational studies with meta-analysis. British Medical Journal 2010 340:b5569.

Warren GW, Kasza KA, Reid ME, Cummings KM, Marshall JR. Smoking at diagnosis and survival in cancer patients. International Journal of Cancer 2013 132(2):401–410.

Walter V, Jansen L, Hoffmeister M, Brenner H. Smoking and survival of colorectal cancer patients: systematic review and meta-analysis. Annals of Oncology 2014 25(8):1517–1525.


Conclusions

Despite the lack of solid evidence from interventional studies, which are for the most part not feasible in humans, it is clear that smoking, alcohol use and recreational drug consumption are somehow able to impair male fertility, with possible synergistic, rather than addictive, effects. Impairments in spermatogenesis and sperm parameters as well as increased DNA methylation and oxidative stress have been observed in humans and animal models alike similarly, effects on endocrine control of reproductive and sexual function have been reported in clinical and experimental studies (Tables 2 and 3, Fig. 1). Discontinuation of all these habits should be suggested in all patients undergoing investigation for infertility in order to provide the best outcomes, although little is known in regards to the time needed for cessation of negative effects.


Centers for Disease Control and Prevention (US) National Center for Chronic Disease Prevention and Health Promotion (US) Office on Smoking and Health (US) .

In 1964, the Surgeon General released a landmark report on the dangers of smoking. During the intervening 45 years, 29 Surgeon General’s reports have documented the overwhelming and conclusive biologic, epidemiologic, behavioral, and pharmacologic evidence that tobacco use is deadly. Our newest report, How Tobacco Smoke Causes Disease, is a comprehensive, scientific discussion of how mainstream and secondhand smoke exposures damage the human body. Decades of research have enabled scientists to identify the specific mechanisms of smoking-related diseases and to characterize them in great detail. Those biologic processes of cigarette smoke and disease are the focus of this report.


Reactive oxygen species (ROS) and reproduction

The involvement of ROS in IVF outcomes from lifestyle factors

ROS are produced as by-products of the normal metabolism of oxygen and they include a range of molecules such as hydrogen peroxide (H2O2), superoxide anion (O2), hydroxyl free radical (OH · ), among others [45]. Excessive production of ROS can cause deleterious effects on cell membranes, DNA and proteins. Consequently, there must be a balance between excessive formation of ROS and antioxidant defences [45]. In turn, oxidative stress is the term used to describe the uncontrolled production of ROS and decreased/impaired antioxidant function [46]. ROS have been found to cause effects on the reproductive system as a result of endogenous synthesis. However, lifestyle choices such as smoking, chronic alcohol consumption, and poor nutritional habits (i.e. low fruits and vegetables, high lipids and sugar), potentiate the endogenous production of ROS and the exogenous exposure, promoting oxidative stress (Fig. 1) . Since excessive ROS and oxidative stress cause adverse effects on the reproductive system, it is reasonable to assume they also have an impact on IVF outcomes.

ROS, cigarette smoking and alcohol

Some of the health risks associated with inhaling cigarette smoke are due to the chronic effects of excessive oxidative stress. Cigarette smoke has been found to contain over 4000 chemicals [47], and a smoker can be directly exposed to over 10 15 ROS per puff in the gas phase of smoking in addition to poisonous cigarette tar [48]. Furthermore, those authors point out that tar, the particulate matter retained on the cigarette filter, has been found to contain polyphenols, while the gas phase smoke has been found to contain high concentrations of nitric oxide (NO). These two phases contain oxidizing chemicals, which exposes the lungs as well as the entire organism to oxidative stresses [49]. Smokers have also been found to have lower circulating concentrations of antioxidants, which may exacerbate rising ROS levels derived from cigarette smoke. Furthermore, alcohol has also been implicated as the source of ROS that contributes to the pathogenesis of alcoholic liver disease, as demonstrated by detection of lipid peroxidation markers in the liver of alcoholic patients [50]. However, given the extent of knowledge related to the consequences of excessive oxidative stress, it is surprising that little research exists examining the impact of ROS derived from alcoholic drinks and cigarettes, on the reproductive system. Consequently, more research needs to be undertaken to fully determine the influence of this source of ROS on fertility.

ROS and male fertility

Research conducted over the past 25 years has suggested that a possible cause of sperm dysfunction is oxidative stress [51, 52]. Sperm naturally produce different ROS types, including NO, O2 · , and H2O2 [53, 54]. Even though excessive levels of ROS can have a detrimental effect on sperm quality and therefore male fertility, not all ROS produced by sperm are harmful as low levels of ROS play a physiological role in the regulation of capacitation, hyperactivation and the binding of the sperm to the zona pellucida [55]. On the other hand, there are a few positive effects of ROS on sperm, but when the amount of ROS exceeds the already limited antioxidant defences of sperm, oxidative stress occurs.

Under low-grade chronic oxidative stress-inducing conditions, damage to the sperm plasma membrane and DNA ensues. Research has found that sperm derived from infertile men display damage to plasma membrane proteins leading to loss of plasma membrane function, which leads to altered functions in sperm motility, ability of sperm to bind to the zona pellucida and sperm-oocyte function [56]. Sperm with low motility, DNA fragmentation damage and non-viable sperm produce higher levels of ROS [56]. An Australian study showed that DNA fragmentation in sperm from ART patients is correlated with expression of 8-OHdG (8-oxo-2-deoxyguanosine), a marker for oxidative stress-induced DNA damage [57]. DNA fragmentation is negatively correlated with pregnancy in natural and ART conceptions such as IVF, but not following intracytoplasmic sperm injection (ICSI) [58].

Another study found that sperm DNA fragmentation was negatively correlated with number of quality embryos and pregnancy rate [58]. This suggested there is a relationship between oxidative stress in sperm and pregnancy outcome in IVF patients. As has been previously mentioned, our research found that for male smokers there was an increased risk of first-trimester pregnancy loss (Table 3). Cigarette smoking is recognized as a source of ROS and increased ROS has been found to cause sperm DNA damage, therefore this could be the potential mechanistic cause of the increased risk of pregnancy loss related to male smokers.

ROS and female fertility

ROS has a deleterious effect on the development of human oocytes, as well as developing embryos [59]. Oxidative stress is thought to be one of the major causes of female fertility problems such as tubal infertility, endometriosis [60] and polycystic ovary syndrome [61]. A study conducted in 2013, found significantly increased levels of ROS in women failing to become pregnant from a wider sample of women undergoing IVF treatment [60]. In addition, they also found that women with higher levels of ROS produced more immature and lower quality embryos. These results suggest that in women undergoing IVF, pregnancy outcome is affected by the presence of oxidative stress in both endometriosis and tubal infertility. The direct effect of ROS on IVF treatment in females has not been examined at length and this is an interesting are of research requiring more attention.


Science for Sale

Scientists were the perfect foil for the tobacco industry's public relations response to allegations that cigarette smoking was injurious to health. Scientists could be counted on to call for more research, giving the impression that there was controversy. In addition, by supporting scientific research, the industry would be seen as doing something positive to address the serious allegations that smoking was harmful (43).

The “Frank Statement to Cigarette Smokers” informed the public that the tobacco industry “will cooperate closely with those whose task it is to safeguard the public health” and to support independent research into all phases of tobacco use and health. According to a TIRC press release, the purpose of the organization was to “…encourage and support qualified research scientists in their efforts to learn more about smoking and health” (44). However, in the first year of operation, the TIRC did not fund any independent research, instead used the resources to mount an aggressive public relations campaign (45). In 1955, Dr. Clarence Little, the first Scientific Director of TIRC, appeared on the Edward R. Murrow show and was asked, “Dr. Little have any cancer-causing agents been identified in cigarettes?” Dr. Little replied, “No. None whatever, either in cigarettes or in any product of smoking, as such.” Dr. Little was also asked, “Suppose the tremendous amount of research going on were to reveal that there is a cancer causing agent in cigarettes, what then?” Dr. Little replied, “It would be made public immediately and just as broadly as we could make it, and then efforts would be taken to attempt to remove that substance or substances” (46).

However, by the late 1950s, it was becoming increasing difficult for the TIRC to appear free from the influence of tobacco manufacturers. It was for this reason in 1958 that the communications committee of the TIRC split off to form the TI. The TI charter listed the following among its duties: dissemination of scientific and medical material related to tobacco, cooperating with governmental agencies and public officials with reference to the tobacco industry, and promoting the public good will (47). Over its 40-year history (1958-1998), the TI was the collective voice of the tobacco industry. In 1958, the TI started its operation with just four people but increased to a staff of 32 by the mid-1970s (48). Budget documents reveal that the funding sources and management structure of TIRC and TI were essentially the same (49).

The Surgeon General's 1964 Report on Smoking and Health left little doubt about whether smoking was harmful to health yet, the tobacco companies continued to insist that the case against smoking was unproven. However, tobacco companies also recognized it was becoming increasing difficult for them to suggest that they were supporting independent research on smoking and health given their financial stake in the outcome. In an effort to create a perception of independence from the tobacco companies 1 month after the Surgeon General issued his first report on smoking and health, the TIRC changed its name to CTR (50). However, the management of CTR remained intact, and evidence shows that industry lawyers started to exert greater control over how CTR research funds were expended (4, 51-54).

From 1964 onward, the TI frequently made reference to the fact that qualified scientists challenged the evidence that smoking caused disease. Yet, many of these so-called independent scientists were recruited and had their research programs supported by the tobacco industry through the TIRC/CTR (55, 56). For example, in 1970, the TI sponsored the “Truth” public service campaign that informed the public that there was a scientific controversy about whether smoking caused disease (57-59). The “Truth” campaign encouraged people to contact the TI to get a copy of a “White Paper” that included quotes from scientists challenging the evidence that smoking caused the disease. Lawyer-controlled “special project accounts” were used to recruit and support scientists who were willing to make statements and/or conduct research that would be favorable to the industry's view that causes other than smoking were responsible for lung cancer and other diseases (51-54). Table 2 provides examples of public statements made by tobacco industry spokespersons between 1954 and 1997 regarding the smoking and health “controversy.”

Selected comments from industry spokespersons about smoking and health

Although TIRC and CTR did fund legitimate peer reviewed research on cancer and other tobacco-related health issues, much of the research that was supported was far removed from addressing the question of whether cigarette smoking caused cancer or other diseases. Evidence that CTR funded research projects had little to do with smoking and health was confirmed in a 1989 survey of CTR-funded scientists, which asked grantees if their research had anything to do with understanding the relationship between smoking and health. Only one of six scientists responded affirmatively to this question (60).

Internal documents from the industry acknowledge that TIRC/CTR was largely a public relations asset for them rather than a real research endeavor to address the smoking and health controversy (51-54). A 1970 letter from Helmut Wakeham, then Vice President of the Corporate Research and Development at Philip Morris, to the President of the TI summed up this view: “nobody believes we are interested in the truth on this subject and the fact that a multi-billion dollar industry has put up 30 million dollars for this over a ten-year period cannot be impressive to a public which at the same time is told we spend upwards of 300 million dollars in one year on advertising” (61).

The tobacco company conspiracy to manufacture a false controversy about smoking and health is summarized in a 1972 TI memorandum, which defined the strategy as consisting of three parts: (a) “creating doubt about the health charge without actually denying it” (b) “advocating the public's right to smoke, without actually urging them to take up the practice” and (c) “encouraging objective scientific research as the only way to resolve the question of the health hazard” (62). In her analysis of the purpose of the industry's jointly funded “research” organizations, Judge Kessler observed that the TI, TIRC, CTR, and CIAR helped the industry achieve its goals because they “sponsored and funded research that attacked scientific studies demonstrating harmful effects of smoking cigarettes but did not itself conduct research addressing the fundamental questions regarding the adverse health effects of smoking” (ref. 8, see pages 1532-33).

In summary, the internal industry documents show how tobacco companies deliberately confused the public debate about smoking and health by creating and supporting research organizations that were never really interested in discovering the truth about whether smoking was a cause of disease.


Secondhand Smoke Risks

Secondhand smoke is the smoke that comes from the burning end of a cigarette, cigar, or pipe. Secondhand smoke also refers to smoke that’s breathed out by a person who is smoking.

Secondhand smoke contains many of the same harmful chemicals that people inhale when they smoke. It can damage the heart and blood vessels of people who don’t smoke in the same way that active smoking harms people who do smoke. Secondhand smoke greatly increases adults’ risk of heart attack and death.

Secondhand smoke also raises the risk of future coronary heart disease in children and teens because it:

The risks of secondhand smoke are especially high for premature babies who have respiratory distress syndrome and children who have conditions such as asthma.


Practical Work for Learning

Class practical

Establish the effect of unlit cigarettes on the apparatus by running the filter pump for 10 minutes. (There should be no effect.) Smoke at least two different cigarettes, and compare their effect on the white-coloured mineral wool and on the indicator solution.

Lesson organisation

This procedure should be carried out in a fume cupboard as a teacher demonstration.

Apparatus and Chemicals

Apparatus as in alternative diagrams shown below:

Conical flask, 250 cm 3 , 1 or 2

Glass tubes, bent to right angles, 2 or 4 (Note 2)

Rubber bungs, two-holed, 1 or 2

Hard glass tube, shaped to hold a cigarette,
1 or 2

White-coloured mineral wool, superwool, glass wool or polymer wool for aquarist filters

Alternatives/ additions:
Connector to allow thermometer to be held in the smoke stream near the cigarette

U-tubes containing white-coloured mineral wool to replace tubes A and B

Hydrogencarbonate indicator (equilibrated with air) in place of Universal indicator.

For the class – set up by technician/teacher:

Filter pump or hand-operated vacuum pump (Note 1)

Clamp stand, boss and clamp, 2

Dishes to collect ash from cigarettes

Health and Safety and Technical notes

Carry out the procedure in a fume cupboard.
It is essential to avoid skin contact with the tars collected.

1 If your water supply does not support a filter pump, use a hand-operated vacuum pump, or a syringe to draw air through the apparatus

2 Check that the tips of the longer glass tubes are below the surface of the indicator solution, and that the shorter glass tubes are well above the surface even if the liquid bubbles.

3 Disassemble the apparatus in a fume-cupboard avoiding skin contact with the tars. Wear protective gloves (preferably nitrile). Place the tar-soaked material in a plastic bag which is sealed before disposal with normal refuse. Wipe the glass with a paper towel soaked in a suitable solvent, such as ethanol (FLAMMABLE) and dispose of the paper towel with the tarry wool. The apparatus is difficult to clean, so re-use in future years. Store in a box or sealed plastic bag to contain the smell. (See CLEAPSS Laboratory Handbook.)

Ethical issues

Cigarettes and smoking provide a rich context for ethical discussions. The first reported research indicating links between lung cancer and cigarette smoking was published in 1950, and in the UK smoking has been banned in public places. There is scope for debate about our rights to make risky lifestyle choices as well as the responsibility of government to promote public health. The commercial drive of tobacco companies and the tax revenue to government from tobacco sales are factors that could influence the reliability of information from different sources. It is hard to find information presented impartially on the subject of smoking and cancer. It is worth trying to identify who has funded or supported any piece of reported impartial or scientific research.

Procedure

SAFETY: Cigarette packets carry health warnings. Schools and colleges are usually non-smoking premises on the grounds of the stated health risks of cigarette smoke. Set up the apparatus in a fume cupboard, and avoid contact with the smoke or close contact with the contents of the tubes at the end.

Parts of the apparatus near the cigarette may be hot at the end, so take care when disassembling to weigh the tubes.

Preparation

a Find the mass of tubes A and B, and write the masses on paper associated with the apparatus.

Investigation

b This is often set up with one lit cigarette and the second unlit as a control. Consider running air through 2 unlit cigarettes (of different types) for 10 minutes to establish that this has no visible effect on the cotton wool or the indicator. Then you could use the apparatus to compare two different types of cigarette – for example normal and low tar, the same brand with and without its filter, packet cigarette vs hand-rolled.

c Start the filter pump. Light the cigarette/s and run until the cigarette is nearly smoked.

d Switch off the filter pump and see what happens to the final few millimetres of cigarette. (This will be particularly interesting if you are comparing packet cigarette with hand-rolled, as rolling tobacco contains fewer ingredients to keep it burning.)

e Note the visible changes to the cotton wool and the indicator.

f Find the mass of tubes A and B. Calculate the increases in mass.

g Disassemble the apparatus avoiding skin contact with the tar (Note 3).

Teaching notes

This demonstration makes a good starter activity for the subject of smoking. Students may be surprised at the amount of tar collecting in the mineral wool from just one cigarette. If you want to pass the wool around for students to smell (which can have a dramatic impact), remove it from the tube using a spatula and put it in a beaker to remove the risk of students touching the tar.

Effects of tobacco smoke on the body:

  • Smoke from tobacco paralyses cilia in the trachea and bronchi for approximately an hour after a cigarette has been smoked.
  • Dry dust and chemicals in the smoke irritate the lungs, causing more mucus to be secreted. Cilia normally sweep this mucus away, but smoke has paralysed them. Mucus builds up and if this becomes infected it can cause bronchitis.
  • Tar is a dark brown, sticky substance, which collects in the lungs as the smoke cools. It contains carcinogens – chemical substances known to cause cancer.
  • Carbon monoxide is a gas which combines with haemoglobin, the oxygen-carrying substance in the red blood cells, even more readily than oxygen does. So it reduces the oxygen-carrying capacity of the blood by as much as 15% in heavy smokers. Unlike the reaction with oxygen, the reaction is irreversible.
  • Nicotine is the addictive drug that makes smoking such a hard habit to give up. It is responsible for the yellow staining on a smoker's fingers and teeth. Nicotine can harm the heart and blood vessels too – it makes the heart beat faster, the blood pressure rise, and the blood clot more easily.

It is hard to find information presented without an agenda on the subject of smoking and cancer. There are links below to a range of sources of information.

As with many issues relating to health and lifestyle choices, it is difficult to isolate the effects of any individual factor. Some reports indicate connections with socio-economic profiles that may also significantly influence health.

There is scope to discuss the meaning of risk measurements, and to try to track down original research papers in order to assess their methodology.

There is a link below to a report on the detailed analysis of the contents of the smoke from a range of brands. This is an independent analysis presented on the Tobacco Manufacturers' website. It doesn’t connect the smoke contents to specific health risks, but it does mention using ISO conditions for smoking cigarettes (ISO 3308:2000). The idea of an ISO standard routine analytical cigarette-smoking machine might interest some students. The smoking machine puffs with a puff volume of 35 ± 0.2 cm 3 , and with a 2.0 ± 0.02 second puff duration once every 60.0 ± 0.5 seconds.

The ISO standard machine makes a much more detailed analysis than the apparatus suggested above. The instructions for a smoking machine that would be acceptable for an ISO accredited test list 24 factors which must be controlled or measured by the machine. These include:

  • puff duration – the length of time during which the port is connected to the suction mechanism: 2.00 ± 0.2 seconds
  • puff volume – the volume leaving the butt end of the cigarette and passing through the smoke trap
  • puff frequency – the number of puffs in a given time: one puff every 60 ± 0.5 seconds measured over 10 consecutive puffs
  • dead volume – the volume which exists between the butt end of the cigarette and the suction mechanism
  • draw resistance – negative pressure applied to the butt end under test conditions to sustain a volumetric flow of 17.5 cm 3 / s, exiting the butt end when the cigarette is encapsulated in a measurement device to a depth of 9mm

Ask students to evaluate your apparatus compared with this list of factors. What difference do you think it makes if the apparatus smokes continuously or puffs the cigarette? Why is it important that there is an internationally-recognised standard way of assessing cigarettes?

Evaluate your apparatus compared with this diagram.

Some reports of cigarette analysis refer to NFDPM – which is nicotine free dry particulate matter, otherwise known as “tar”. TPM stands for total particulate matter.

Health and safety checked, September 2008

Web links

http://www.the-tma.org.uk/benchmark/covering_letter.htm
This connects to the UK Benchmark study report of an analysis of tobacco from cigarettes on the market in the UK. (Scroll to the bottom of the page for links to reports). The Final report explains the methodology of the analysis. There is a summary on p5 of Part 1 of the report which lists all brands tested and the components of their smoke.

http://www.ash.org.uk/
Action on Smoking and Health (ASH) is a campaigning public health charity that works to eliminate the harm caused by tobacco.

http://www.forestonline.org/
Forest is a media and political lobby group. Their purpose is to protect the interests of adults who choose to smoke or consume tobacco in its many forms.

http://info.cancerresearchuk.org/cancerstats/causes/lifestyle/tobacco/
Cancer Research UK is the leading funder of cancer research in the UK and has stated goals of improving the lives of cancer patients and helping people to understand the choices they make.

http://www.beep.ac.uk/content/493.0.html
Beep is the Bioethics Education Project. This link takes you directly to the pages on tobacco and health risks and choices.

Doll, R. and A.B. Hill, Smoking and carcinoma of the lung. Preliminary report. British Medical Journal, 1950: p. ii:739-48.

http://www.ncbi.nlm.nih.gov/pubmed/15292933?dopt=Abstract
Abstract of ‘The cumulative risk of lung cancer among current, ex- and never-smokers in European men’ – referenced on Cancer Research UK website.

http://www.ncbi.nlm.nih.gov/pubmed/15741188?dopt=Abstract
Abstract of ‘Estimate of deaths attributable to passive smoking among UK adults: database analysis’ – referenced on Cancer Research UK website.

(Websites accessed October 2011)

© 2019, Royal Society of Biology, 1 Naoroji Street, London WC1X 0GB Registered Charity No. 277981, Incorporated by Royal Charter


The reasons why smoking is bad for you

Smoking damages nearly every organ in the body. People can significantly reduce their chance of smoking-related disease by giving it up.

Smoking is the leading preventable cause of early disease and death in the United States. Giving up smoking is difficult for many people, but the number of former smokers is increasing all the time.

According to the Centers for Disease Control and Prevention (CDC) , current smoking in the U.S. has declined from 20.9% in 2005 to 13.7% in 2018. The number of smokers who have quit is also rising.

In this article, we look at the health impact of smoking, including its effects on the brain, heart, lungs, and immune system. We also discuss the benefits of quitting.

Every year, more than 480,000 people die in the U.S. due to tobacco-related diseases — around 1 in 5 of all deaths — according to the American Cancer Society.

They also state that around half of people in the U.S. who keep smoking will die from smoking-related causes.

Life expectancy is at least 10 years less for smokers compared with nonsmokers. The American Cancer Society state that smoking shortens lifespan by about 12 years in males and 11 years in females.

The CDC comment that smoking causes more deaths in the U.S. each year than the following combined:

Tobacco contains poisonous substances that affect people’s health. Two of these poisons are:

  • Carbon monoxide. Car exhaust fumes also produce this substance, and it is fatal in large doses. It replaces oxygen in the blood and starves the organs of oxygen, stopping them from functioning correctly.
  • Tar. This is a sticky, brown substance that coats the lungs and affects breathing.

While the statistics are alarming, it is important to bear in mind that giving up smoking reduces the risk of disease dramatically.

Below, we discuss the impact smoking can have on different parts of the body.

Smoking can increase the likelihood of having a stroke by 2–4 times . Strokes can cause brain damage and death.

One way that stroke can cause brain injury is through a brain aneurysm, which occurs when the wall of a blood vessel weakens and creates a bulge. This bulge can burst and cause a subarachnoid hemorrhage, which can lead to a stroke.

Chemicals in tobacco smoke increase the chance of heart problems and cardiovascular diseases.

Smoking causes atherosclerosis, which is when plaque builds up in the blood and sticks to the artery walls. This makes them narrower, reducing blood flow and increasing the risk of blood clots.

Smoking also damages the blood vessels, making them thicker and narrower. This makes it harder for blood to flow, and also increases blood pressure and heart rate.

Smoking has links with the following cardiovascular conditions:

  • coronary heart disease, one of the leading causes of death in the U.S
  • aheart attack, as smoking doubles the risk of heart attack
  • blockages that reduce blood flow to the skin and legs
  • stroke due to blood clots or burst blood vessels in the brain

Even smokers who smoke 5 or fewer cigarettes a day may develop early signs of cardiovascular disease.

Carbon monoxide and nicotine make the heart work harder and faster. This means that smoking makes it more challenging to exercise. A lack of exercise further increases the risk of health problems.

According to the National Institutes of Health (NIH), smoking reduces bone density, making the bones weaker and more brittle. Smoking can also impair bone healing after a fracture.

Researchers find it difficult to say whether this is a direct effect of smoking, or due to other risk factors prevalent in people who smoke. These include lower body weight and doing less physical exercise.

This may affect females more than males. Females are more prone to osteoporosis and broken bones.

Quitting smoking, even later in life, can help limit bone loss linked with smoking.

The immune system protects the body against infection and disease.

According to one 2017 study , smoking reduces immune function and causes inflammation in the body. This can lead to autoimmune conditions, including:

Smoking also has links with type 2 diabetes.

The lungs are perhaps the most obvious organ that smoking affects.

It often takes many years before a person notices any symptoms of smoking-related lung disease. This means that people may not receive a diagnosis until the disease is quite advanced.

Smoking can impact the lungs in several ways. The primary reason is that smoking damages the airways and air sacs — known as alveoli — in the lungs.

Three of the most common smoking-related lung conditions in the U.S. are:

  • Chronic obstructive pulmonary disease (COPD). COPD is a long-term disease. It causes wheezing, shortness of breath, and chest tightness. COPD is the third leading cause of death in the U.S.
  • Chronic bronchitis. Chronic bronchitis occurs when the airways produce too much mucus. This leads to a long-lasting cough and inflamed airways. Over time, scar tissue and mucus can completely block the airways and cause infection.
  • Emphysema:Emphysema is a type of COPD that reduces the number of alveoli and breaks down the walls between them. This makes it difficult to breathe, even at rest, and over time, a person may need an oxygen mask.

Other lung diseases caused by smoking include pneumonia, asthma, and tuberculosis.

Smoking can have several effects on oral health and may cause:

Smoking irritates the gum tissues. The American Dental Association (ADA) state that smoking increases the risk of gum disease, which can add to halitosis.

Smoking can also affect the reproductive system and fertility.

Females who smoke can have more difficulty becoming pregnant. In males, smoking can cause impotence by damaging blood vessels in the penis. It can also damage sperm and affect sperm count.

According to some studies, males who smoke have a lower sperm count than those who do not.

Smoking while pregnant increases a number of risks for the baby, including:

  • premature birth
  • pregnancy loss
  • low birth weight
  • sudden infant death syndrome
  • infant illnesses

Smoking reduces the amount of oxygen that can reach the skin. This speeds up the aging process and can make skin appear dull or gray.

  • facial wrinkles, especially around the lips
  • baggy eyelids
  • uneven skin coloring, such as a yellow or gray tone
  • dry, coarse skin
  • temporary yellowing of the fingers and fingernails

Smoking reduces how quickly skin wounds heal, increases the risk of skin infections, and increases the severity of skin conditions, including psoriasis.

Smoking increases the risk of many types of cancer. According to the National Cancer Institute, tobacco smoke contains around 7,000 chemicals, of which at least 69 can cause cancer.

Figures from the American Cancer Society state that smoking causes around 30% of all cancer deaths in the U.S., and 80% of all lung cancer deaths.

Lung cancer is the leading cause of cancer death in both men and women. It is one of the most difficult to treat.

Smoking is a risk factor for the following cancers:

Cigars, pipe-smoking, menthol cigarettes, chewing tobacco, and other forms of tobacco all cause cancer and other health problems. There is no safe way to use tobacco.

While the statistics are alarming, the good news is that quitting smoking reduces the risk of disease and death significantly. The risks drop further, the longer a person refrains from smoking.

In fact, some research says that quitting before the age of 40 reduces the risk of dying from smoking-related disease by about 90%.

These statistics illustrate the health benefits of quitting smoking:

  • Cardiovascular risks: After 1 year of quitting, the risk of having a heart attack drops sharply.
  • Stroke: Within 2–5 years, the risk of a stroke reduces to half that of a non-smoker.
  • Cancers: The risks for mouth, throat, esophagus, and bladder cancer drop by half within 5 years of quitting, and 10 years for lung cancer.

Soon after quitting, people experience the following health benefits that can significantly improve their quality of life and serve as reminders of the health benefits that quitting can have:

  • breathing becomes easier
  • daily coughing and wheezing reduces then disappears
  • sense of taste and smell get better
  • exercise and activities become easier
  • circulation to the hands and feet improves

Though quitting can be stressful, people often start to notice their daily stress levels are much lower than when they were smoking within 6 months or so.

Quitting smoking is a different journey for everyone, and what works for one person will not always work for the next. Try out a few different ways to see which ones work best.

When trying to quit smoking, these tips may help:

  • Make lists of reasons why it is a good idea to quit. Read over these when the temptation to smoke strikes.
  • Use an app to track your progress. Reaching milestones, such as a day without smoking, can help motivate a person to continue. There are many free and paid apps on the market.
  • Try nicotine replacement products. Nicotine patches, gums, and lozenges can help reduce cravings, making it easier to resist at any particular moment.

Many people find that reaching out to a healthcare provider for support can help them quit for good. A doctor can prescribe medication, such as varenicline (Chantix). Experts currently recommend this as a first-line therapy for people who want to quit smoking.


Watch the video: Ένζυμα - βιολογικοί καταλύτες (August 2022).