Smoke and the Asthma Epidemic: A Reality Check

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I think we all have a pretty good idea what may be causing this

EPIDEMIC

Smoke and the Asthma Epidemic: A Reality Check

Date of original release: 7/17/00

http://www.forces.org/research/files/asthma.htm

We've all heard that smoking and second-hand smoke cause asthma, but

a growing body of evidence is challenging the veracity of this old

saw.

The most recent study to exonerate smoking and tobacco smoke as a

cause of asthma was published in the British Medical Journal July 8,

2000. [1]

In this 20-year, intergenerational study, researchers found that the

rate of asthma had doubled between l976 and l996, even as the

smoking rate dropped by half during that same period. Asthma and hay

fever increased for both smokers and non-smokers, but the increase

was higher for non-smokers. The steep rise in asthma was

dramatically underscored by the fact that prescriptions for steroid

inhalents for treatment of the disease rose more than six-fold

between l980 and l990 alone.

This pattern of precipitous increases in asthma coupled with

significantly diminishing smoking rates is not unique to the

population described by the ish researchers in their BMJ

article. Asthma and allergy rates are skyrocketing among adults and

children in all developed countries, though not in less-developed,

poorer countries.

Experts are baffled by the asthma epidemic. In most countries it

strikes hardest at the children of middle-class and wealthy parents,

and no one knows why.

" It is very confusing, " said Professor Ulrich Wahn, pediatric

specialist at Humboldt University in Berlin. " These are middle

class parents, who have taken on board the need for a healthy

lifestyle: low rates of smoking in pregnancy, low rates of smoking

in the home and low levels of pet ownership, together with high

rates of breast feeding....There is clearly an unidentified factor

that is so strong it can overcome all the lifestyle changes we

encourage parents to adopt. " [2]

These good, European middle-class parents have stopped smoking,

banished it from their homes, and yet their kids are getting

allergies and asthma far more often than children in more smoking-

tolerant times ever did.

In the United States, too, the incidence of adult and childhood

asthma has climbed to an unprecedented high during the past twenty

years, while smoking and exposure to environmental tobacco smoke

[ETS] have decreased significantly during the same period.

Between 1980 and l995, the number of people reporting asthma in the

U.S. more than doubled (from 6.7 million to 13.7 million) [3], a

75% increase in the rate per 100,000 population. [4] And, after a

sharp increase beginning in the early l990s, the rate is still

climbing. The Centers for Disease Control estimates the l998 rate

at 17.3 million, a 150% increase since 1980. [5]

Between l980 and l995, the adult smoking rate decreased from 33.2 to

24.7, a drop of 25%. [6] In the late l990s the overall smoking rate

has remained steady at between 24 and 25 percent of the adult

population, far less than its peak of 42.6% in l966.

Though asthma rates have risen uniformly throughout the country,

there are some regional differences. The inverse relationship

between asthma rates and smoking and between asthma rates and

exposure to ETS can be seen quite clearly by comparing extremes at

the state level.

California has had the second-lowest smoking rate in the U.S. for

many years. In l998, its adult smoking rate was 19.2. [7] It also

has the most draconian smoking bans in the country. Nevertheless,

California has the largest estimated number of persons with asthma

in the U.S., with an estimated l998 prevalence of 7.1% [8]

Utah, which has had by far the lowest smoking rate in the U.S. for

many years but which has not had the sweeping smoking bans so

characteristic of California, had a l998 adult smoking rate of

14.2. The estimated l998 asthma prevalence in the state was 6.7%.

Kentucky has the highest smoking rate in the United States and has

implemented few restrictions on public smoking. In l998 Kentucky's

adult smoking rate was 30.8%, but its estimated l998 asthma

prevalence was only 5.9%.

Asthma, Children and Minorities in the U.S.

Childhood asthma is on the increase in Europe and North America

alike. According to Dr. Talal Nsouli of the American College of

Allergy, Asthma and Immunology, the number of U.S. children with

asthma has doubled in 15 years, and the rate for children under age

five has increased 160%. [9]

One major difference between the European and American childhood

asthma epidemics is that in the U.S. the disease strikes

particularly hard among inner-city children and some of the

country's ethnic minorities. [10] Blacks and Hispanics have higher

rates than do non-hispanic whites.

Neither maternal smoking during pregnancy nor exposure to ETS

appears to account for the ethnic differences in rates of childhood

asthma.

" The prevalence of asthma among children of Hispanic (mainly Puerto

Rican) mothers with one or more children older than 9 mo. of age was

18.4%, for blacks it was 11.3%, and for non-Hispanic whites it was

7.4%....In addition, increased risk for asthma in these children was

not associated with higher reporting of environmental tobacco smoke

(ETS) exposure. " [11]

Since l989, when maternal smoking rates during pregnancy began to be

compiled nationally, Hispanic mothers have consistently had the

lowest smoking rates during pregnancy of all three groups, and white

non-hispanics have had the highest: [12]

Hispanic - l989: 8.0 1993: 5.0

Black - l989: 17.1 1993: 12.7

White - l989: 20.4 1993: 16.8

Note that the rates for all three groups dropped significantly

between l989 and l993. Overall maternal smoking during pregnancy

continued to drop in l995 to 14.0 and in l996 to 13.6, a 31%

decrease from the overall rate of 19.5 in l989.

Given these statistics, it seems clear that even active smoking by

pregnant women does not play a causitive role in the current

childhood asthma epidemic. Moreover, if active smoking by the

mother during pregnancy is not causally involved, then it's

certainly not plausible that prenatal exposure to ETS would be

causally involved either.

Occupational Asthma

Just as asthma is rising among children, it is also rising among

adults in the workplace. One expert summarized it nicely in a book

review in The New England Journal of Medicine:

" We know of more than 250 substances that can cause occupational

asthma, and the list is expanding. Occupational asthma not only

represents a substantial proportion of all cases of asthma but also

is one of the main occupational diseases. The unsolved scientific

questions concerning the increasing incidence of occupational asthma

in recent decades, the socioeconomic effects of the disease, and

prevention are the current challenges. " [13]

One thing is certainly true: In recent decades, workplace smoking

bans have been enacted far and wide throughout the United States,

particularly since the mid-l980s. By l992, workplace smoking

restrictions covered about four-fifths of all indoor workers,

according to a government survey. [14] Since then, many more

workplace smoking bans have been implemented, often as a result of

state mandates. In l995, California banned smoking in all

workplaces except restaurants and bars, and it has since banned

smoking indoors even in those venues.

Nevertheless, occupational asthma continues to rise, and the Centers

for Disease Control estimated that California had more cases of

asthma in l998 than did any other state.

Asthma and Allergies

Concurrently with the rise in asthma has come an increase in the

numbers of people with allergies. According to the National

Institutes of Health, as many as 50 million Americans--roughly 20%

of the population--now suffer from allergies. [15]

Almost any substance can cause an allergic reaction in those who are

sensitized to it, but the substances involved most frequently are

dust mites, mold, pollen, cockroach droppings and pet dander.

Some people believe they are allergic to tobacco smoke. However, it

has not been scientifically demonstrated that tobacco smoke contains

antigens which would spark an allergic reaction. [16] Furthermore,

since exposure to ETS has decreased dramatically in public places,

the workplace, and even in the home, while allergies have increased,

it isn't plausible that ETS is a factor in the increase in allergies

and allergic reactions.

Unlike severe asthma attacks, allergic reactions are not generally

life threatening, but they can be if they are severe enough to

provoke anaphylactic shock. According to a recent study published

in the British Medical Journal, hospital admissions for acute

anaphylaxis in England increased nearly two-fold between l991 and

l995. By far the most frequent causes of anaphylaxis in this study

were allergic reactions to therapeutic drugs and to food. [17]

The relationship between allergy and asthma is not clearly

understood. Most people with allergies do not have asthma, but most

asthmatics do have allergies which can trigger attacks.

The most common triggers for asthma are dust mites, pet dander, mold

and cockroach droppings. But emotional stress, viral infections,

food allergies, and pollen from grass and ragweed also initiate

attacks in many people.

Merely reducing asthmatics' exposure to suspected triggers doesn't

solve the problem, however. " Reducing allergen exposure, although

intuitively obvious as a management approach, has had a less than

stellar track record when applied to asthma control in clinical

practice. " [18] Furthermore, in many cases, acute asthma attacks

frequently occur without an obvious trigger. [19]

What Causes Asthma?

Asthma is not a new phenomenon. It has existed as a known clinical

syndrome for more than 2000 years, [20] and yet its cause remains

elusive.

In modern times, theories about its root cause have abounded. Many

experts have posited that it is primarily a psychosomatic disorder,

brought on by emotional distress. Others have blamed everything

from cockroaches to dust mites to air pollution and tobacco smoke.

But because asthma is increasing so dramatically in the l990s,

medical scientists are re-thinking the old theories. After all,

cockroaches, pets, dust, air pollution, stress and ETS were at least

as abundant before the asthma epidemic as they are now. Certainly

ETS was far more pervasive in our society prior to the sudden rise

in asthma.

Dr. ez, [21] director of respiratory sciences at

the University of Arizona, is one of a growing number of experts who

have completely changed their thinking about asthma.

" Like most people, I assumed tobacco smoke and pollution were the

problem--this was the politically correct way to think. But these

factors turned out not to play a major role. In high-pollution

areas, in low-pollution areas, among all ethnic groups, there was

asthma. Clearly, something else was involved. " [22]

Dr. ez, like many other asthma specialists, has come to

believe that the problem lies in the lack of challenge to the

developing immune systems of the young in modern affluent

societies. In other words, our children's environment is too

sterile and they are overly protected from microbial and parasitic

challenges. He says, " Just as you need to use your eyes to develop

sight and your legs to develop the muscles to walk, your immune

system develops through its experience. By legitimately protecting

our kids from dangerous infections we may have kept parts of their

immune systems from maturing. " Dr. ez believes that increased

use of antibiotics may be part of the problem, given recent

estimates that 40% of children in the U.S. are treated with

antibiotics for a month or more before their first birthday. [23]

A variety of new explanations for the rising asthma rates are also

being put forth by asthma specialists: lack of physical activity,

changing patterns of diet, genetic predisposition, the increasing

presence of man-made chemicals, and rising levels of emotional

stress, among others.

In the midst of all this uncertainty, at least one thing seems

clear: Whatever is causing more and more of our children and adults

to contract and suffer from asthma, it's not tobacco smoke.

___________________________

ENDNOTES

1 - Upton M N, McConnachie A, McSharry C, Hart C L, G D,

Gillis C R, Watt G C M, " Intergenerational 20 year trends in the

prevalence of asthma and hay fever in adults: the Midspan family

study surveys of parents and offspring, " BMJ 2000;321:88-92 (8 July

2000)

2 - Derbyshire, , " Cossetted children more prone to

allergies, " Electronic Telegraph, 5 July 2000.

3 - Centers for Disease Control and Prevention, MMWR

4/24/98, " Surveillance for Asthma--United States, l960-1995. "

4 - Centers for Disease Control and Prevention, MMWR

12/4/98, " Forecasted State-Specific Estimates of Self-Reported

Asthma Prevalence--United States, l998. "

5 - Asthma Prevention Program of the National Center for

Environmental Health, Centers for Disease Control and

Prevention, " At-A-Glance, " l999.

6 - Centers for Disease Control and Prevention, TIPS, " Percentage of

adults who were current, former or never smokers...National Health

Interview Surveys, Selected Years--United States, l965-l995. "

7 - Centers for Disease Control and Prevention, " Prevalence of

current cigarette smoking among adults, by state and sex--United

States, Behavioral Risk Factor Surveillance System, l998. " Smoking

rates for all three states are from this source.

8 - CDC, MMWR 12/4/98 47;1022-1025. " Forecasted State-Specific

Estimates.... " The estimated prevalence data for all three states

are from this source.

9 - Kim, Eun-Kyung, " First Lady Launches Asthma Program, " Associated

Press, 5/4/99.

10 - Centers for Disease Control and Prevention, MMWR,

4/24/98, " Surveillance for Asthma--United States, l960-1995. Asthma

Surveillance Summary. "

11 - Beckett W S, Belanger K, Gent J F, Holdord T R, Leaderer B

P, " Asthma among Puerto Rican Hispanics: a multi-ethnic comparison

study of risk factors, " Am J Respir Crit Care Med, l996 Oct 154:4 Pt

1 894-9. For this study, 9,276 mothers were interviewed during

l993-l994.

12 - National Center for Health Statistics, " Mothers who smoked

cigarettes during pregnancy, according to mother's detailed race,

Hispanic origin, educational attainment, and age: Selected States,

l989-93. "

13 - Xaver Baur, M.D., Book Review of Asthma in the Workplace [Ed.

by L. Bernstein, M Chan-Yeung, J Malo and D Bernstein, New York,

Marcel Dekker, l999], New England Journal of Medicine, 342:15, April

13, 2000.

14 - J. son, " Smoking Fictions, " Washington Post,

2/25/98, p.A17.

15 - Thoms Goetz, " Don't Inhale: Hotel Air Quality Becomes an Issue

With Clients, " The Wall St. Journal, 6/18/99.

16 - O'Connor G T, et al, " The role of allergy and nonspecific

airway hyperresponsiveness in the pathogenesis of chronic

obstructive pulmonary disease, " American Review of Respiratory

Disease, 140:225-252, l989. Several studies have been conducted

using sham smoke and tobacco smoke with subjects who claimed to be

allergic to or " sensitive " to tobacco smoke (e.g. Urch B, Shephard R

J, Silverman F, " Pulmonary Function Responses to Passive Smoking and

the Influence of Suggestibility, " l985, Health & Welfare, Canada),

but these studies found no significant difference in the subjects'

reactions to the sham smoke compared to moderate or heavy tobacco

smoke.

17 - Sheikh A, Alves B, " Hospital admissions for acute anaphylaxis:

time trend study, " BMJ 320:1441, 27 May 2000.

18 - Gelfand E W, " Environmental Control and Immune Modulation in

Asthma Treatment, " paper presented at the American Lung

Association/American Thoracic Society International Conference,

4/27/99.

19 - Gianfranco Del Prete, M.D., Book Review of Difficult Asthma

[Ed. by Holgate S T, Boushey H A, Fabbri L M, London: Dunitz,

l999] in The New England Journal of Medicine, 342:5, Feb 3 2000.

20 - Ibid.

21 - Dr. ez authored Chapter 7 ( " Passive Smoking and

Respiratory Disorders Other Than Cancer " ) and co-authored Chapter 8

( " Assessment of Increased Risk for Respiratory Illnesses in Children

From Environmental Tobacco Smoke " ) of the U.S. EPA report on

Respiratory Health Effects of Passive Smoking: Lung Cancer and Other

Disorders, US EPA, Dec., l992.

22 - Ellen Ruppel Shell, " Does Civilization Cause Asthma? " Atlantic

Monthly, May 2000.

23 - Ibid.