Smoking and Your Health

HOW DO WE REALLY KNOW SMOKING IS HARMFUL?

Evidence has been accumulating for years relating cigarette smoking to disease. As cigarette consumption in the first half of this century increased, many began to suspect a connection with lung cancer. Several pioneering studies published in the 1940s and 1950s established this link. However, the evidence was not universally accepted and was challenged especially by tobacco companies during this period. In the 1950s, to help resolve the issue, the U.S. Public Health Service reviewed the published evidence from all parts of the world. Based on evidence accumulated up until l957, Surgeon General Leroy E. Burney stated ". . . excessive smoking is one of the causative factors in lung cancer." An official "Public Health Statement" reinforcing this position was published in the Journal of the American Medical Association, November 28, 1959. This official government position formed the basis for further developments in the l960s.

In l962 the British Government issued its own report, concluding: "Cigarette smoking is a cause of lung cancer and bronchitis, and probably contributes to the development of coronary heart disease . . .". About this time other studies linked cigarettes to various diseases. As a result many people, including U.S. congressmen, called for further investigation.

On June 7, 1962 Surgeon General Luther L. Terry announced the establishment of an expert committee to undertake a comprehensive review of all data on smoking and health. The result was the first Surgeon General's report on Smoking and Health, published in January 1964. This report proved pivotal for all subsequent government action toward cigarettes. No new research had been done for this report, only an objective and critical analysis of all the research done in the world up to that time. Results of this study were conclusive: based on epidemiologic, clinical, and basic research, cigarettes were found to be causally related to human diseases including lung cancer, chronic bronchitis and heart disease.

WHAT HAS BEEN LEARNED SINCE THE 1964 SURGEON GENERAL'S REPORT?

Since 1964 the government has periodically updated its reports on smoking and health to include all new evidence accumulated each year. In 1979 the Public Health Service published a totally new Surgeon General report, including all the evidence on smoking and health accumulated between 1964 and 1979. The 1979 report confirms an ever wider range of human diseases caused by cigarette smoking, and states that cigarettes are "far more dangerous than was supposed in 1964."

The 15­year interval between reports had established dangers to women smokers (most of the evidence prior to 1964 dealt with men only). We now know, for example, that lung cancer deaths among women increase as more women smoke longer. "Women who smoke like men die like men who smoke." We also know that smoking during pregnancy adversely affects the fetus and increases the risk of birth defects. Women who smoke during pregnancy are more apt to have low birth weight babies, increasing the risk to the neonate.

In addition, we have learned that smoking greatly increases the risk of workers exposed to certain occupational hazards, such as asbestos fibers. The 1979 report documents also the rather shocking increase in smoking among teenage girls. The percentage of girls age 12 to 14 who smoke increased eight­fold between 1968 and 1978.

Perhaps most importantly, the 1979 Report puts to rest any possible objection that the evidence against cigarettes is sketchy and circumstantial. This document – a review of 15 years of solid research – deals a final blow to those who doubt the dangers of cigarette smoking.

WHAT PERCENTAGE OF THE POPULATION SMOKES?

The total percentage of the adult population that smokes cigarettes has declined, from 42 percent in 1965 to 33 percent in 1980. There are estimated 30 million ex­smokers in this country.

Although the percentage of smokers fell, the population increased enough during this period to keep the number of smoking adults about the same­53.3 million in 1965 and 52.4 million in 1980. Partly as a result, the number of cigarettes sold has gone up, from 529 billion in 1965 to 615 billion (in 1978); this represents an increase in the number of cigarettes sold per active smoker.

Despite the increases in number of cigarettes smoked, the percentage decline of adult smokers indicates definite progress. Indeed, without the massive educational effort launched since the 1964 Surgeon General Report, probably almost half of the adult population would be smoking cigarettes today.

Table 1 gives the percentage of adult smokers in 1965, 1978, and 1980.

WHAT ARE THE DISEASES CAUSED BY CIGARETTES?

Based on the 1964 and 1979 Surgeon General reports, the diseases or conditions shown in Table 2 are now known to be related to cigarette smoking.

In addition, cerebrovascular disease (stroke) is thought possibly related to cigarette smoking, but the evidence is yet inconclusive.

It should be emphasized that the above conditions would still occur in the population if there were no cigarette smoking, but much less frequently. Thus, cigarettes are estimated to cause 90 percent of lung cancer, 65 percent of laryngeal cancer, 25 percent of coronary artery disease, and so forth. For the individual, not smoking considerably lessens the chances of contracting any of these illnesses.

WHAT IS THE WORST EFFECT OF CIGARETTE SMOKING?

Considering the number of people affected, the worst effect of smoking is not lung cancer, bronchitis, or emphysema. It is coronary artery heart disease (CHD), a disease involving the vessels (coronary arteries) supplying blood to the heart. Smoking is one of three major Independent risk factors for CHD; the others are high blood pressure and elevated serum cholesterol. The risk of CHD increases both with the number of cigarettes smoked and with the presence of other risk factors.

Hardening of these arteries (coronary arteriosclerosis) and resultant heart attacks (coronary thrombosis) killed over 640,000 Americans in 1978. Through careful statistical analysis of patients who smoke and patients who get heart disease, it has been concluded that about 25 percent of these deaths would have not occurred if patients had not smoked cigarettes. Over 160,000 of these deaths were directly attributable to cigarette smoking.

HOW MANY DEATHS FROM LUNG CANCER, BRONCHITIS AND EMPHYSEMA ARE ATTRIBUTABLE TO CIGARETTES?

In the United States, lung cancer accounts for over 100,000 deaths per year, over 90 percent of these directly due to cigarette smoking. Chronic obstructive pulmonary diseases (bronchitis and emphysema) – diseases almost exclusively due to cigarettes – cause another 50 to 60 thousand deaths each year. Over 300,000 smoking­related deaths (cancer, COPD, and heart disease) occur each year. This makes cigarette smoking the number one known cause of death in the United States.

This statistic makes an interesting contrast to the number of Americans who died:

• During Battle in World War II (1941­1945) — 292,131
• During Battle in VietNam (1964­1972) — 45,926
• In Motor Vehicle Accidents (1978) — 53,600

The mortality ratio for all smokers of cigarettes is about 1.7 when compared to nonsmokers. This means life expectancy is shortened by cigarette smoking – a 30­year­old, 2­pack­per­day smoker has a life expectancy 8.1 years less than his nonsmoking counterpart.

There is a dose­response relationship between smoking and mortality. The risk of dying from a cigarette­related illness (lung cancer, coronary heart disease, and so forth) increases the more one smokes.

HOW DOES CIGARETTE SMOKE RESULT IN HEART DAMAGE?

Cigarette smoke is actually made up of many compounds and gases, divided into three main groups.

Nicotine: a chemical present in all cigarettes and responsible for giving one a "flushed" feeling.

Tar: represents all of the particulate matter left over from the smoke after removal of moisture and nicotine; tar is the smokers residue, and is the main cause of pulmonary disease, particularly lung cancer.

Carbon monoxide (CO): a colorless, odorless gas present in all cigarette smoke. (In addition, CO is a component of automobile exhaust, and can be found whenever incomplete combustion takes place.)

Nicotine and carbon monoxide can have damaging effects on the heart. Nicotine can constrict or narrow the coronary arteries that supply blood to the heart. When this occurs in patients who have hardening of the coronary arteries, the result may be decreased oxygen delivery to the heart muscle. The patient may experience severe chest pain, known as angina. If oxygen delivery is severely impaired, part of the heart muscle dies and the patient experiences a heart attack.

Carbon monoxide can contribute to this process. CO binds avidly with hemoglobin in the red blood cells. Hemoglobin bound with CO can no longer carry oxygen the more carbon monoxide in the blood, the less oxygen is available. Inhaling two packages of cigarettes a day may remove up to 15 percent of the bloods oxygen. In other words, people who smoke this much may be walking around with up to 15 percent less oxygen in their blood than if they didn't smoke. An otherwise normal person has ways of compensating for this oxygen deficit; however, when combined with the damaging effects of nicotine and already hardened coronary arteries, the result can be devastating.

Heart attacks do kill nonsmokers, although other risk factors, such as high blood pressure and elevated blood cholesterol, are usually present. If you have never smoked, you may still get coronary artery disease, but the chances are less likely. Smoking doubles the risk of dying from coronary artery disease for men and increases the risk for women, but not to the same level as for male smokers.

WHAT ABOUT PIPE AND CIGAR SMOKING?

Cancers of the mouth and throat occur much more commonly in pipe and cigar smokers than in nonsmokers; also, pipe smoking is a major cause of lip cancer. However, lip and mouth cancers are relatively less common diseases than the major killers – lung cancer, heart disease, bronchitis, and emphysema.

Death rates from lung cancer are close to those for nonsmokers if the smoke is not inhaled. The more pipe or cigar smoke is inhaled, the more death rates and medical problems rise. Thus, pipes and cigars are not inherently "safe" to use, but the overall habits of pipe and cigar smokers (less is smoked, less is inhaled, compared to cigarette smokers) do tend to minimize the overall risks.

IS CIGARETTE SMOKE ADDICTING?

The original 1 964 Surgeon General Report stated that smoking was not an addiction since there were no withdrawal symptoms on quitting. Research in the intervening years has clearly shown the opposite to be true. Nicotine in cigarette smoke is addictive, and smokers can and often do get withdrawal symptoms when they quit. Symptoms include restlessness, irritability, intense craving for a cigarette, and trouble in concentration. The ability to measure nicotine levels in the blood has enabled researchers to closely study nicotine's addicting aspects.

In the preface to the 1979 Surgeon General Report nicotine is blamed for the apparent paradox of an educated smoking public wanting to quit the habit but unable to ". . . perhaps because nicotine is a powerful addictive drug." Without nicotine in tobacco, cigarette smokers would not have the intense desire to continue smoking and would be no more inclined to smoke than, say, eat a candy bar. Gratifying perhaps, but not addicting.

HOW CAN ONE OVERCOME THE NICOTINE ADDICTION AND STOP SMOKING?

It is fair to say there is no proven or widely accepted method of stopping smoking. Table 3 broadly categorizes the many methods advocated today. Within each category are dozens of variations, many advertised and promoted for profit. The philosophical differences in approach, as well as the sheer number of methods advocated, attest to the lack of any simple, acceptable method that will help a majority of smokers. Although various stop­smoking methods have been advocated as long as cigarettes have been a recognized problem, the relatively recent appreciation of nicotine's addicting property has provided a rationale for a host of methods, old and new. These are discussed later in this chapter.

IF NICOTINE IS ADDICTING, WHY ARE SOME PEOPLE ABLE TO QUIT "COLD"?

Different people respond differently to habituating substances. Nicotine's addicting properties are mild compared to the opiates such as heroin. Abrupt withdrawal does give some people unpleasant effects, such as a gnawing sensation in the stomach, a headache, and, not least, an intense craving for cigarettes (actually for nicotine). It is likely that the intensity of symptoms ranges widely in any group of smokers and that many people can either ignore or overcome them in their desire to quit. There may be an attenuation of symptoms with age so that older people, who have also smoked longer, are better able to quit than younger people smoking the same number of cigarettes a day. Whatever the explanation, the fact remains that millions have been able to kick the habit without much, if any, ill effect.

WHAT IS THE BEST METHOD TO QUIT SMOKING?

If by this question one means what is the most healthful method, quitting "cold turkey" is the obvious answer. The effects of nicotine withdrawal are not medically significant, continued smoking is.

As to which method is likely to be most successful, there is no single answer. The many different approaches and individual methods, with none the clear winner, mean each smoker has to find what works best for him or her.

The categories in Table 3 are based on methods the smoker might seek out. Also discussed are methods used by physicians when patients are not seeking help but must quit nonetheless. The single most effective method of getting a patient to quit is constant reinforcement by his or her physician, done in an intelligent, persistent manner, using the physician's own nonsmoking behavior as example.

1. Quitting Cold

Quitting cold means stopping smoking suddenly without substituting any other potentially harmful tobacco product. This is also the method chosen, consciously or not, by most people who have kicked the habit. For unknown reasons many people are able to just stop, period. The impetus may come from years of no­smoking propaganda, a personal or family illness, or some sudden insight into their problem. This is certainly the most economical of all methods.

2. Weaning

Weaning means slowly decreasing the amount smoked each day, either by decreasing the number of cigarettes, their potency, or the amount of smoke inhaled from each cigarette.

There are an enormous number of weaning variations. One popular type uses a series of four filters and advertises "one day at a time"; each filter, used for two weeks, is designed to eliminate more of the toxic smoke than the one preceding it. At the end of the eight week period about 90 percent of the tar, nicotine, and carbon monoxide is said to be removed from the smoke. Like all weaning methods it may work for some but carries no unique advantages.

There are many books that advocate specific programs based on some form of weaning. They are all essentially self­help and teach the smoker how to quit on his or her own. Techniques advocated include: smoking only at certain times of the day regardless of location or activity; listing important trigger activities and then, one at a time, gradually eliminating cigarettes associated with them; keeping cigarettes in inaccessible areas or locking them up; and restricting smoking to an uncomfortable place.

Even with highly motivated people, weaning is not always successful. Unfortunately for some, weaning may reinforce the need to smoke. If you have the will to make a choice between quitting cold and weaning off cigarettes, choose the former.

3. Nicotine Substitution

The idea behind methods based on nicotine addiction is to maintain a high blood nicotine level without inhaling harmful tar and carbon monoxide in cigarette smoke. Most of these methods are designed to provide nicotine in a form other than inhaled tobacco smoke; among these the most popular consist of using tobacco without smoking it – chewing or snuffing. Less popular are tobacco less aids, such as nicotine chewing gum and nicotine lozenges, and nicotine substitutes, drugs and similar properties.

Tobacco Without Smoking. Snuff is pulverized chewing tobacco; a pinch of snuff can be placed in the nose or in the cheek. An article in the medical journal Lancet showed that nicotine from snuff is readily absorbed into the bloodstream.

Chewing tobacco is nonpulverized and is chewed slowly in the mouth. Like snuff, it also provides nicotine without the harmful effects of cigarette smoke.

Nicotine Without Tobacco. Nicotine­containing chewing gum and nicotine patches have been developed as an aid to satisfy the nicotine craving without inhaling tobacco smoke. Experience with these aids suggests they only work with highly motivated people, and are successful perhaps a third of the time.

Drugs Similar to Nicotine. Tobacco substitutes contain lobeline, a natural substance obtained from dried leaves and herbs that has similar effects as nicotine. However, controlled studies have not found lobeline any better than a placebo (inert drug). There is also no evidence that tranquilizers such as Valium offer any benefit for people who wish to quit smoking.

4. Behavioral

Many programs attempt to alter the behavior of the smoker in a way that discourages or eliminates all smoking. Fear is the simplest technique employed, often used by physicians on their patients. By detailing possible consequences such as lung cancer and emphysema, doctors hope that patients will quit smoking out of fear of the consequences. Often, however, this backfires because some patients may smoke even more to relieve anxiety.

Adverse conditioning is a form of behavioral therapy that seeks to make the smoking experience very unpleasant. There are drugs on the market that claim to make cigarette smoke taste unpleasant; these have not found widespread acceptance smoking. The rapid smoking technique has received much attention recently and has been presented in reputable medical journals. Here the patient smokes very rapidly until he or she becomes sick with dizziness or nausea. Because their carbon monoxide level is increased, patients with heart disease may be at some risk from this procedure, though it appears safe for otherwise healthy people. This technique is still under investigation and is obviously limited to only a small number of people in a controlled setting.

Clinics and organized groups, profit and nonprofit, usually employ some form of behavior modification. They may help some people to stop smoking, at least temporarily. The problem in evaluating their effectiveness is that the programs begin with people who have already decided to quit and just need a slight push; they are not as successful with the less motivated. A number of organizations sponsor such groups, including:

Some programs, particularly in industry, reward people monetarily if they stop smoking. These programs can be very effective.

In conclusion, there is a plethora of anti­smoking drugs, devices, educational programs, and other methods advertised to help people stop smoking. As may be expected, no single program is widely accepted.

CAN HARM COME FROM INHALING SECOND­HAND SMOKE?

"Second­hand smoke" refers to smoke given into the atmosphere from a lighted cigarette. It comes from two sources. The first is side stream smoke, which enters the air directly from the burning end of a cigarette. The second source is mainstream smoke, which is the smoke inhaled by the smoker and then exhaled into the atmosphere. An average cigarette burns for 12 minutes, polluting the air continuously with side stream smoke, while mainstream smoke is exhaled by the smoker for part of this time.

Side stream smoke has higher concentrations of noxious compounds than mainstream smoke. For example, about twice as much tar and nicotine, three times as much carcinogenic 3­4 benzpyrene (a component of "tar"), and five times as much carbon monoxide are in side stream smoke as compared to mainstream smoke. Thus, exposure to other people's cigarettes (passive smoking) means exposure to the same harmful chemicals and gases that cause cancer, heart disease, and other cigarette­related illnesses.

Passive Smoking by Healthy People

Based on epidemiologic studies similar to those in smokers, several harmful effects of passive smoking have been shown in groups of healthy people, including:

Newborns: Children born of smoking mothers have lower birth weights and more medical problems, on the average, than children from nonsmoking mothers.

Children: Asthma symptoms are much more frequent, common colds more prolonged and pneumonia more common, in children of smoking parents compared with children brought up in a nonsmoking environment.

Adults: Several studies point to the potential adverse effects of inhaling other people's cigarette smoke. However, the evidence so far indicates, at most, minor respiratory impairment from passive smoking.

The evidence for serious disease from passive smoking is unclear. Although at least one study purported to show an increased risk of lung cancer in passive smokers, this has not been substantiated.

Passive Smoking by Patients with Medical Problems

Common sense tells us that diseased hearts and lungs can only get worse from a continued assault of cigarette smoke, even when passively inhaled. Several studies have scientifically confirmed this, at least in patients who suffer from angina pectoris, or heart pains that come from lack of oxygen to the heart muscle. In the early 1970s Dr, Wilbert Aronow and colleagues at Long Beach Veterans Hospital in California studied groups of patients with angina. In one study, they did tests of heart and lung function before and after patients were driven for 90 minutes in heavy freeway traffic with the car windows open. These patients were tested to see how long it took for heart pains to occur. Dr. Aronow repeated the tests with the patients breathing compressed air from a tank while driving through the traffic. The results: Exposure to freeway traffic air increased carbon monoxide levels in the blood and caused heart pain to occur sooner than when the patients breathed non-polluted air.

It is probable that second­hand smoke is very dangerous to some people, but not by itself a major cause of alarm for healthy people exposed infrequently. There is as yet no conclusive evidence that long­term exposure in otherwise healthy people will have the same devastating effects as occur in regular smokers. However, prudence dictates that one should avoid cigarette smoke as much as possible.

ARE THE LOW TAR AND NICOTINE CIGARETTES SAFER THAN THE OLDER BRANDS?

This is a complex question and the topic of the 1981 Surgeon General's report on Smoking and Health. As with prior reports, many contributing scientists and physicians reviewed all the relevant evidence. Among the conclusions of the report were:

There is no safe cigarette and no safe level of consumption. Smoking cigarettes with lower yields of "tar" and nicotine reduces the risk of lung cancer and, to some extend, improves the smoker's chance for longer life, provided there is no compensatory increase in the amount smoked. However, the benefits are minimal in comparison with giving up cigarettes entirely. The single most effective way to reduce hazards of smoking continues to be that of quitting entirely ... A final question unresolved is whether the new cigarettes being produced today introduce new risks through their design, filtering mechanisms, tobacco ingredients, or additives. The chief concern is additives. The Public Health Service has been unable to assess the relative risks of cigarette additives because information was not available from manufacturers as to what these additives are.

DOES QUITTING SMOKING IMPROVE SURVIVAL?

No matter how long one has smoked, quitters can expect to live longer than those who continue the habit. Dr. G. D. Friedman and colleagues studied 25,917 people who answered detailed health questionnaires over a ten year period at Kaiser Permanente Medical Centers in Oakland and San Francisco. Based on the results of multiple questionnaires during this period, the subjects were grouped according to their smoking habits as persistent smokers, persistent quitters, temporary quitters, and never smokers. Cause of death was determined from California death certificates for several diseases, including lung cancer and coronary artery heart disease.

Quitting and Coronary Artery Heart Disease (CHD)

A major purpose was to determine if quitting smoking improved survival from CHD. It had been suggested that people who quit live longer because they are healthier to begin with, and that during their smoking years those who will later quit smoke less, have less pre­existing heart disease, are thinner, or possess other characteristics that distinguish them as a group from those who will persist in smoking. Not so. When all other factors were accounted for, the study found persistent quitters have less than half the chance of dying from CHD as do persistent smokers! Quitting smoking is an independent factor that substantially lessens the risk of dying from CHD. In fact, the risk for quitters is about the same as for those who've never smoked.

Quitting and Lung Cancer

Dr. Friedman's study is also interesting for its results about lung cancer. Compared to never smokers, persistent smokers had a 45 times greater chance of dying from lung cancer; in contrast to CHD, they found that persistent quitters still had a 1 S­fold greater chance of dying from lung cancer.

These are group statistics. Other studies have shown that the longer one has quit smoking, the less the chances of developing (and dying from) lung cancer.

HOW LONG AFTER QUITTING DOES ONE ACHIEVE THE SAME LUNG CANCER RISK AS A NONSMOKER?

The answer to this depends on how long and how much one has smoked. Heavy smokers maintain a definite increased risk of developing lung cancer years after quitting, although after ten years this risk approaches that of nonsmokers. For years the increased risk of developing lung cancer or another serious disease (if one is not already present) is probably negligible,

Fortunately, other benefits of quitting become more immediately obvious. Within one to two days the new nonsmoker has more oxygen carrying capacity than when he or she smoked, since the blood is no longer being polluted with carbon monoxide. Consequently, his or her exercise tolerance improves. Symptoms such as coughing and sputum production also begin to improve within days to weeks after quitting. And, not to be dismissed, money spent on cigarettes becomes available for other things.

IS MARIJUANA HARMFUL TO THE LUNGS?

There is a striking parallel between attitudes toward marijuana today and toward cigarettes 50 years ago. In the 1920s cigarettes were generally regarded as harmless, even relaxing. We now know unequivocally that they are a cause of most lung cancer and disabling chronic lung disease, plus a large proportion of coronary artery disease. Each year hundreds of thousands of Americans die from the effects of cigarette smoking. Despite the enormity of the statistics, it has taken decades of increasing cigarette consumption, first among men, then women, plus countless scientific studies along the way, to appreciate fully tobacco's harmful effects.

Widespread marijuana use is a relatively new phenomenon, largely limited to people under 35. There is simply not the cumulative experience with marijuana that there is with cigarettes; for this reason less is known about its long­term effects.

One of the short­term effects of marijuana (occurring within minutes to hours after inhaling) is an opening up of the airways in asthmatic patients. This "bronchodilating" effect of marijuana smoke has been confirmed in several studies done in the early and mid-1970s. Thus, along with whatever high one obtains, an asthmatic may also notice easier breathing after a few puffs. However, because of the other active (and potentially harmful) ingredients in marijuana smoke, this must be considered the worst imaginable treatment for asthma.

More recent studies suggest that the potential harm from long­term marijuana smoking is similar to that from smoking tobacco. Both are plants whose smoke is inhaled deeply into the lungs. Many chemicals and products of combustion are inhaled when either is smoked (acrolein, formaldehyde, and NO₂, among others). One major difference is that marijuana contains no nicotine. Instead it contains THC (delta­9­tetrahydrocannabinol). THC, the major psychoactive ingredient, is responsible for the high experienced when marijuana is smoked. Along with THC hundreds of other compounds, similar to the "tar" of cigarettes, are also inhaled. For this reason marijuana smoke has the potential for causing the same lung diseases caused by cigarettes.

It is thus not surprising that scientific studies show chronically­smoked marijuana has an irritating effect. The respiratory effects have been demonstrated by Dr. Donald P. Tashkin and associates at UCLA, using volunteers solicited through newspaper advertisements. In one study, daily smoking of an average of five marijuana joints over a period of 47 to 59 days caused mild but statistically significant decreases in several measurements of lung function. This study involved 28 young men.

A more recent study from UCLA included 74 young, habitual marijuana smokers (frequency of smoking ranged from three times a week to several joints every day), with most having a smoking history of over five years. All were white, between the ages of 21 and 33. Their lung function was compared to control groups of non­marijuana­smoking subjects. Results of sophisticated lung function tests showed that marijuana smokers were found to have subtle changes in airflow, mainly in the larger airways of the lungs. In addition, these changes were more pronounced than those found in cigarette­smoking subjects who did not use marijuana! As a possible explanation, Dr. Tashkin postulates that there may be "a greater irritant effect of constituents in marijuana smoke than of those in tobacco smoke ."

Studies such as these must be considered preliminary. Most marijuana smokers are asymptomatic, and the observed lung function changes in the studied subjects may not predict future respiratory difficulties. But since marijuana smoke contains the same or similar respiratory irritants as cigarette smoke, one must logically expect long­term detrimental changes. The current state of knowledge can be summarized by a quote from Dr. Robert L. DuPont, president of the National Institute on Drug Abuse: "Smoke is bad for the lungs, whether it's industrial smoke, tobacco smoke or marijuana smoke,"

Those interested in a summary of all the health effects of marijuana should read Marijuana and Health, a comprehensive review published by the Institute of Medicine. [Return to Table of Contents]