For people who begin tobacco use as adolescents or
young adults, smoke heavily, and continue to smoke, the likelihood of premature
death is virtually ensured.
Two-pack-a-day cigarette smokers can expect to die 7 to 8 years earlier
than their nonsmoking counterparts.
(only nonsmoking-related deaths than can afflict smokers and nonsmokers
alike keep the difference at this level rather than much higher.) not only will these people die sooner, but
they will also probably be plagued with painful, debilitating illnesses for an
extended time. Smoking is responsible
for nearly 440,000 premature deaths each year.
Cardiovascular
Disease
Cardiovascular disease is the leading cause of death
among all adults, accounting for 945,836 deaths in the United States in
2000. Tobacco use, and cigarette smoking
in particular, is clearly one of the major factors contributing to this cause
of death. Although overall progress is being made in
reducing the incidence of cardiovascular-related deaths, tobacco use impedes
these efforts. So important is tobacco
use as a contributing factor in deaths from cardiovascular disease that the
cigarette smoker more than doubles the risk of experiencing a myocardial
infarction, the leading cause of death from cardiovascular disease. Smokers also increase their risk of sudden
cardiac death by two to four times.
Fully one-third of all cardiovascular disease can be traced to cigarette
smoking.
The relationship between tobacco use and
cardiovascular disease is centered on two major components of tobacco smoke:
nicotine and carbon monoxide.
Nicotine and
Cardiovascular Disease
The influence of nicotine on the cardiovascular
system occurs when it stimulates the nervous system to release
nor-epinephrine. This powerful stimulant
increases the heart rate. In turn, an
elevated heart rate increases cardiac output, thus increasing blood
pressure. The extent to which this is dangerous
depends in part on the coronary circulation’s ability to supply blood to the
rapidly contracting heart muscle. The
development of angina pectoris and the possibility of sudden heart attack are
heightened by this sustained elevation of heart attack are heightened by
individuals with existing coronary artery disease.
Nicotine is also a powerful vasoconstrictor of the
peripheral blood vessels. As these
vessels are constricted by the influence of nicotine, the pressure against
their wall increases. Recent research
shows that irreversible atherosclerotic damage to major arteries also occurs
with smoking.
Nicotine also increases blood platelet
adhesiveness. As the platelets become
more and more likely to “clump,” a person will be more likely to develop a
blood clot. In people already prone to
cardiovascular disease, more rapidly clotting blood is an unwelcome
liability. Heart attacks occur when
clots form within the coronary arteries or are transported to the heart from
other areas of the body.
In addition to other influences on the cardiovascular
system, nicotine possesses the ability to decrease the proportion of
high-density lipoproteins (HDLs) and to increase the proportion of low-density
lipoproteins (LDLs) and very-low-density lipoproteins that constitute the
body’s serum cholesterol. Low-density
lipoproteins appear to support the development of atherosclerosis and are
clearly increased in the bloodstream of smokers.
Carbon
Monoxide and Cardiovascular Disease
A second substance contributed to tobacco influences
the type and extent of cardiovascular disease found among tobacco users. Carbon monoxide interferes with oxygen
transport within the circulatory system.
Carbon monoxide is a component of the gaseous phase
of tobacco smoke and readily joins with the hemoglobin of the red blood
cells. Carbon monoxide has an affinity
for hemoglobin 206 times that of oxygen.
Once the hemoglobin of a red cell has accepted carbon monoxide
molecules, the hemoglobin is transformed into carboxyhemoglobin. Thereafter, the carboxyhemoglobin permanently
weakens the red blood cell’s ability to transport oxygen. So long as smoking continues, these red blood
cells remain relatively useless during the remainder of their 120-day
lives. Levels of carboxyhemoglobin in
heavy smokers are associated with significant increases in the incidence of
myocardial infarction.
When a person has impaired oxygen-transporting
abilities, physical exertion becomes increasingly demanding on both the heart
and lungs. The cardiovascular system
will attempt to respond to the body’s demand for oxygen, but these responses
are themselves impaired as a result of the influence of nicotine on the
cardiovascular system. If tobacco does
create the good life, as advertisers claim, it also unfortunately lessens the
ability to participate actively in that life.
Cancer
Over the past 60 years, research from the most
reputable institutions in this country and abroad has consistently concluded
that tobacco use is significant factor in the development of virtually all
forms of cancer and the most significant factor in cancers involving the
respiratory system.
In describing cancer development, the currently used
reference is 20 pack-years, or an amount of smoking equal to smoking one pack
of cigarettes a day for 20 years. Thus
the two-pack-a-day can anticipate cancer-related tissue changes in as few as 10
years, while the half-pack-a-day smoker may have 40 years to wait. Regardless, the opportunity is there for all
smokers to confirm these data by developing cancer as predicted. It is hoped that most people will think twice
before disregarding this evidence.
Data supplied by the American Cancer Society (ACS)
indicate that during 2003 an estimated 1,334,000 Americans developed
cancer. These cases were nearly equally
divided between the sexes and resulted in approximately 556,500 deaths. In the opinion of the ACS, 30% of all cancer
cases are heavily influenced by tobacco use.
Lung cancer along accounted for about 171,900 of the new cancer cases
and 157,200 deaths in 2003. Fully 87% of
men with lung cancer were cigarette smokers.
A genetic “missing link” between smoking and lung cancer was
established, when mutations to an important tumor suppressor gene were
identified. If it was necessary to have
a final “proof” that smoking causes lung cancer, that proof appears to be in
hand.
Cancer of the entire respiratory system, including
lung cancer and cancers of the mouth and throat, accounted for about 185,200
new cases of cancer and 163,700 deaths.
Despite these high figures, not all smokers develop cancer.
Respiratory
Tract Cancer
Recall that tobacco smoke produces both a gaseous and
a particulate phase. As noted, the
particulate phase contains the tar fragment of tobacco smoke. This rich chemical environment contains more
than four thousand known chemical compounds, hundreds of which are known to be
carcinogens.
In the normally functioning respiratory system,
particulate matter suspended in the inhaled air settles on the tissues lining
the airways and is trapped in mucus produced by specialized goblet cells. This mucus, with its
trapped impurities, is continuously swept upward by the beating action of
hairlike cilia of the ciliated columnar epithelial cells lining the air
passages. On reaching the throat, this
mucus is swallowed and eventually removed through the digestive system.
When tobacco smoke is drawn into the respiratory
system, however, its rapidly dropping temperature allows the particulate matter
to accumulate. This brown, sticky tar
contains compounds known to harm the ciliated cells, goblet cells, and the
basal cells of the respiratory lining.
As the damage from smoking increases, the cilia become less effective in
sweeping mucus upward to the throat.
When cilia can no longer clean the airway, tar accumulates on the
surfaces and brings carcinogenic compounds into direct contact with the tissues
of the airway.
At the same time that the sweeping action of the
lining cells is being slowed, substances in the tar are stimulating the goblet
cells to increase the amount of mucus they normally produce. The “smoker’s cough” is the body’s attempt to
remove this excess mucus.
With prolonged exposure to the carcinogenic materials
in tar, predicable changes will begin to occur within the respiratory system’s
basal cell layer. The basal cell begin
to display changes characteristic of all cancer cells. In addition, an abnormal accumulation of
cells occurs. When a person stops
smoking, preinvasive lesions do not repair themselves as quickly as once
thought.
By the time lung cancer is usually diagnosed, its
development is so advanced that the chance for recovery is very poor. Still
today, only 15% of all lung cancer victims survive for 5 years or more after
diagnosis. Most die in a very
uncomfortable, painful way.
Cancerous activity in other areas of the respiratory
system, including the larynx, and within the oral cavity (mouth) follows a
similar course. In the case of oral
cavity cancer, carcinogens found within the smoke and within the saliva are
involved in the cancerous changes.
Tobacco users, such as pipe smokers, cigar smokers, and users of
smokeless tobacco, have a higher (4 to 10 times) rate of cancer of the mouth,
tongue, and voice box.
In addition to drawing smoke into the lungs, tobacco
users swallows saliva that contains an array of chemical compounds from
tobacco. As this saliva is swallowed,
carcinogens are absorbed into the circulatory system and transported to all
areas of the body. The filtering of the
blood by the liver, kidneys, and bladder may account for the higher-than-normal
levels of cancer in these organs among smokers.
Documents released in 1997 from within the tobacco
industry clearly show that the major tobacco companies were aware of tobacco’s
role in the development of cancer and had made a concerted effort to deprive
the American public access to such knowledge.
Chronic
Obstructive Lung Disease
Chronic obstructive lung disease (COLD), also known
as chronic obstructive pulmonary disease (COPD), is a disorder in which the
amount of air that flows in and out of the lungs becomes progressively
limited. COLD is a disease state that is
made up of two separate but related diseases: chronic bronchitis and pulmonary
emphysema.
With chronic bronchitis, excess mucus is produce in
response to the effects of smoking on airway tissue, and the walls of the
bronchi become inflamed and infected.
This produces a characteristic narrowing of the air passages. Breathing becomes difficult, and activity can
be severely restricted. With cessation
of smoking, chronic bronchitis is reversible.
Emphysema causes irreversible damage to the tiny air
sacs of the lungs, the alveoli. Chest
pressure builds when air becomes trapped by narrowed air passages (chronic
bronchitis) and the thin-walled sacs rupture.
Emphysema patients lose the ability to ventilate fully. They feel as though they are
suffocating. You may have seen people
with this condition in malls and other locations as they walk slowly by,
carrying or pulling their portable oxygen tanks.
More than 10 million Americans suffer from COLD. It is responsible for a greater limitation of
physical activity than any other disease, including heart disease. COLD patients tend to die a very unpleasant,
prolonged death, often from a general collapse of normal cardiorespiratory
function that result in congestive heart failure.
Additional
Health Concerns
In
addition to the serious health problems stemming from tobacco use already
described, other health related changes are routinely seen. These include a generally poor state of
nutrition, the gradual loss of the sense of smell, and premature wrinkling of
the skin. Tobacco users are also more
likely to experience strokes (a potentially fatal condition), lose body mass
leading to osteoporosis, experience more back pain and muscle injury, and find
that fractures heal more slowly.
Further, smokers who have surgery spend more time in the recovery
room. Although not perceived as a health
problem by people who continue smoking in order to control weight, smoking does
appear to minimize weight gain. In
studies using identical twins, twins who smoked were six to eight pounds
lighter than their nonsmoking siblings.
Current understanding about why smoking results in lower body weight is
less than complete. One factor may be an
increase in Basal Metabolic Rate (BMR) brought about by the influence of
nicotine on sympathetic nervous system function. Additionally, smokers have a fourfold greater
risk of developing serious gum (periodontal) disease. Also, smokers may need supplementation for
two important water-soluble vitamins, vitamin C and vitamin B.
