The Health Consequences of
Using Smokeless Tobacco

A Report of the

Advisory Committee to the Surgeon General

1986

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Bethesda, Maryland 20992

NIH Publication No. 96-2874
April 1996


CONTENTS

Foreword ......................................... ..v


Preface ........................................... .

Acknowledgments ................................. ..ix

Introduction, Overview, and Conclusions ................ xvii

Chapter 1. Prevalence and lbnds of Smokeless
     lbbaccoUsei.ntheUnitedStates . . . . .l

Chapter 2. Carcinogenesis Associated With
     Smokeless Tobacco Use . . . . .29

Chapter 3. Noncancerous and Precancerous
     Oral Health Effects Associated With
     Smokeless Tobacco Use . . . . . . . .95

Chapter 4. Nicotine Exposure: Pharmacokinetics,
    Addiction, and Other Physiologic Effects . . ,137

Index..................... . . . . . . . . . . . . . ...187

. . .
111


FOREWORD

This report on The Health Consequences of Using Smokeless lbbamo
completes the Public Health Service's initial examination of smokeless
tobacco's role in the causation of cancer, noncancerous and precancer-
ous oral diseases or conditions, addiction, and other adverse health
effects. Almost 30 years after the Public Health Service's first state
ment on the health effects of cigarette smoking, it is now possible to
issue the first comprehensive, indepth review of the relationship
between smokeless tobacco use and health.

Ironically, while cigarette smoking has declined during the past 20
years, the production and apparent consumption of smokeless tobacco
products have risen significantly. These increases are in marked con-
trast to the decline in smokeless tobacco use in the United States during
the first half of this century. Indeed, smokeless tobacco products, par-
ticularly chewing tobacco and snuff, have recently emerged as popular
products for the first time since the turn of the century. National esti-
mates indicate that at least 12 million Americans used some form of
smokeless tobacco during 1985 with use increasing especially among
male adolescents and young male adults.
The increased use and appeal of this product assume major public
health significance because the evidence reveals that smokeless tobacco
can cause oral cancer, can lead to the development of oral leukoplakias
and other oral conditions, and can cause addiction to nicotine. The
strength of the association between these conditions and smokeless
tobacco use combined with the upward trend in this behavior incites the
same alarm as was true with the knowledge that spitting spread tuber-
culosis. That concern led to the original public rejection of tobacco
chewing and dipping as unsanitary and antisocial. It is critical that our
society prevent the use of this health hazard and avoid the tragic
mistake of replacing the ashtray with the spittoon.
This report is the work of numerous experts within the Department
of Health and Human Services and in the non-Federal scientific com-
munity. I express my gratitude for their contributions.

C. Everett Koop, M.D.
U.S. Surgeon General


PREFACE

This report discusses the health consequences of smokeless tobacco
use. It constitutes a comprehensive review by an Advisory Committee
to the Surgeon General of the available scientific literature to determine
whether using smokeless tobacco increases the risk of cancer and non-
cancerous oral diseases and effects, leads to addiction and dependence,
and contributes to other health consequences.
AFTER A CAREFUL EXAMINATION OF THE RELEVANT
EPIDEMIOLOGIC, EXPERIMENTAL, AND CLINICAL DATA,
THE COMMITTEE CONCLUDES THAT THE ORAL USE OF
SMOKELESS TOBACCO REPRESENTS A SIGNIFICANT
HEALTH RISK. IT IS NOT A SAFE SUBSTITUTE FOR SMOK-
ING CIGARETTES. IT CAN CAUSE CANCER AND A NUMBER
OF NONCANCEROUS ORAL CONDITIONS AND CAN LEAD TO
NICOTINE ADDICTION AND DEPENDENCE.
The major overall conclusions of this report are the following:

1. It is estimated that smokeless tobacco was used by at least 12
million people in the United States in 1985 and that half of these
were regular users. The use of smokeless tobacco, particularly
moist snuff, is increasing, especially among male adolescents and
young male adults.

2. The scientific evidence is strong that the use of snuff can cause
cancer in humans. The evidence for causality is strongest for
cancer of the oral cavity, wherein cancer may occur several times
more frequently in snuff dippers compared to nontobacco users.
The excess risk of cancer of the cheek and gum may reach nearly
fiftyfold among long-term snuff users.

3. Some investigations suggest that the use of chewing tobacco may
also increase the risk of oral cancer, but the evidence is not so
strong and the risks have yet to be quantified.

4. Experimental investigations reveal potent carcinogens in smoke
less tobacco. These include nitrosamines, polycyclic aromatic
hydrocarbons, and radiation-emitting polonium. The tobacco-
specific nitrosamines often have been detected at levels 100 or
more times higher than Government-regulated levels of other
nitrosamines permitted in foods eaten by Americans.

vii


5. Smokeless tobacco use can lead to the development of oral leuko-
plakias (white patches or plaques of the oral mucosa), particularly
at the site of tobacco placement. Based on evidence from several
studies, a portion of leukoplakias can undergo transformation to
dysplasia and further to cancer.

6. Gingival recession is a commonly reported outcome of smokeless
tobacco use.

7. A number of studies have shown that nicotine exposure from
smoking cigarettes can cause addiction in humans. In this regard,
nicotine is similar to other addictive drugs such as morphine and
cocaine. Since nicotine levels in the body resulting from smokeless
tobacco use are similar in magnitude to nicotine levels from
cigarette smoking, it is concluded that smokeless tobacco use also
can be addictive. Besides, recent studies have shown that nicotine
administered orally has the potential to produce a physiologic
dependence.

8. Some evidence suggests that nicotine may play a contributory or
supportive role in the pathogenesis of coronary artery and periph-
eral vascular disease, hypertension, peptic ulcers, and fetal mortal-
ity and morbidity.

. . .
Vlll


ACKNOWLEDGMENTS

This report was prepared by the Department of Health and Human
Services under the direction and general editorship of Joseph W. Cullen,
Ph.D., Chairman of the Advisory Committee on the Health Conse
quences of Using Smokeless lbbacco. The following individuals were
members of the Advisory Committee:

Catherine S. Bell, M.S., Acting Chief, Prevention Research Branch,
Division of Clinical Research, National Institute on Drug Abuse,
Rockville, Maryland

William Blot, Ph.D., Chief, Biostatistics Branch, Division of Cancer
Etiology, National Cancer Institute, Bethesda, Maryland
James P. Carlos, D.D.S., M.P.H., Associate Director, Epidemiology
and Oral Disease Prevention Program, National Institute of Dental
Research, Bethesda, Maryland

Joseph W. Cullen, Ph.D., Chairman of the Advisory Committee, Dep-
uty Director, Division of Cancer Prevention and Control, National
Cancer Institute, Bethesda, Maryland
J. David Erickson, D.D.S., M.P.H., Ph.D., Chief, Birth Defects and
Genetic Diseases Branch, Centers for Disease Control, Atlanta,
Georgia

Manning Feinleib, M.D., Dr.P.H., Director, National Center for Health
Statistics, Hya ttsville, Maryland

Jerome Jaffe, M.D., Director, Addiction Research Center, National
Institute on Drug Abuse, Baltimore, Maryland
Michael McGinnis, M.D., M. A., M.P.P., Deputy Assistant Secretary for
Health, Director, Office of Disease Prevention and Health Promo
tion, United States Public Health Service, Washington, D.C.
Robert Mecklenburg, D.D.S., M.P.H., Assistant Surgeon General,
Chief Dental Officer, United States Public Health Service, Rockville,
Maryland

Susan Sieber, Ph.D., Deputy Director, Division of Cancer Etiology,
National Cancer Institute, Bethesda, Maryland
Sumner J. Yaffe, M.D., Director, Center for Research for Mothers and
Children, National Institute of Child Health and Human Develop-
ment, Bethesda, Maryland

The Advisory Committee was supported by the following technical
experts in the areas listed below:

ix


Carcinogenesis

William Blot, Ph.D. (Coordinator), Chief, Biostatistics Branch, Division
of Cancer Etiology, National Cancer Institute, Bethesda, Maryland
Gayle Boyd, Ph.D., Research Psychologist, Division of Cancer Preven-
tion and Control, National Cancer Institute, Silver Spring, Maryland
Virginia L. Em&r, Ph.D., Associate Professor of Epidemiology, Uni-
versity of California, San Francisco, California
Curtis Harris, M.D., Chief, Laboratory of Human Carcinogenesis, Divi-
sion of Cancer Etiology, National Cancer Institute, Bethesda,
Maryland

Dietrich Hoffmann, Ph.D., Associate Director, Chemistry and Bio-
chemistry, Naylor Dana Institute for Disease Prevention, American
Health Foundation, Valhalla, New York
Kenneth Rothman, Dr.P.H., Professor of Family and Community
Medicine, University of Massachusetts Medical School, Worcester,
Massachusetts

David Schottenfeld, M.D., Chief, Division of Epidemiology, Memorial
Sloan-Kettering Cancer Center, New York, New York
Steven R. Tmnenbaum, Ph.D., Professor of Toxicology and Food
Chemistry, Department of Applied Biological Sciences, Massachu-
setts Institute of Technology, Cambridge, Massachusetts
David B. Thomas, M.D., Dr. PH., Head Program in Epidemiology,
Fred Hutchinson Cancer Research Center, Seattle, Washington

Non-Cancer Od Effects

Arden G. Christen, D.D.S., M.S.D., M.A., Chairman, Department of
Preventive Dentistry, Indiana University Dental School, Indianapo
lis, Indiana

Stephen B. Corbin, D.D.S., M.P.H., Chief, Dental Disease Prevention
Activity, Center for Preventive Services, Centers for Disease Control,
Rockville, Maryland
Robert 0. Greer, Jr., D.D.S., Sc.D., Professor, Division of Oral Pathol-
ogy and Oncology, University of Colorado Health Sciences Center,
Denver, Colorado

Lireka P. Joseph, Dr.P.H., Medical Radiation Specialist, Food and Drug
Administration, Rockvihe, Maryland
Stephen S. Kegeles, Ph.D., Professor, Department of Behavioral Sci-
ences and Community Health, University of Connecticut Health
Center, Farmington, Connecticut
Matthew Kinnard, Ph.D., Health Science Administrator, Periodontal
and Soft Tissue Diseases Research Branch, National Institute of
Dental Research, Bethesda, Maryland
Dushanka Kleinman, D.D.S., M.Sc.D., Special Assistant to the Asso
ciate Director for Program Coordination, Epidemiology and Oral
Disease Prevention Program, National Institute of Dental Research,
Bethesda, Maryland

X


Robert Mecklenburg, D.D.S., M.P.H. (Coordinator), Assistant Surgeon
General, Chief Dental Officer, United States Public Health Service,
Rmkdle, Maryland
Kathleen L. Schroeder, D.D.S., M.S., Assistant Professor, Department of
Oral Biology, Ohio State University College of Dentistry, Columbus,
Ohio

Addiction and Dependence

Catherine S. Bell, M.S. (Coordinator), Acting Chief, Prevention Re
search Branch Division of Clinical Research, National Institute on
Drug Abuse, RockviRe, Maryland
Neal Benowitz, M.D., Associate Professor of Medicine, Chief of Clinical
Pharmacology and Experimental Therapeutics, University of Cali-
fornia, San Francisco, california
Anthony Biglan, Ph.D., Research Scientist, Oregon Research Institute,
Eugene, Oregon
John Grabowski, Ph.D., Associate Professor, Department of Psychiatry,
School of Medicine, Louisiana State University, Shreveport, Louisiana
Steven Gust, Ph.D., Reseaxh Associate, Department of Psychiatry,
University of Minnesota, Minneapolis, Minnesota
Jack Hennmgfield, PhD., Chief, Biology of Dependence and Abuse
Potential Assessment Laboratory, Addiction Research Center,
National Institute on Drug Abuse, Baltimore, Maryland
Lynn Kozlowski, PhD., Senior Scientist, The Smoking Research Pro
gram, Addiction Reseamh Foundation, Toronto, Ontario, Canada
Norman A. Krasnegor, PhD., Chief, Human Learning and Behavioral
Branch, Center for Research for Mothers and Children, National
Institute for Child Health and Human Development, Bethesda,
Maryland
Ovide Pomerleau, PhD., Chief of Psychology Service, Veterans Admin-
istration Medical Center, Newington, Connecticut

The following individuals prepared draft chapters or portions of the
report as indicated:

Chapter I. Prevalence and Fends of Smokeless lbbacco Use
      in the United States

Gayle Boyd, PhD., Research Psychologist, Division of Cancer Preven-
tion and Control, National Cancer Institute, Silver Spring, Maryland
Rebecca Cline, PhD., Senior Associate, Prospect Associates, Rockille,
Maryland
Charles Darby, M.A., `Ikhnical`Support Staff Coordinator for Addic-
tion and Dependence Experts, Senior Associate, Prospect Associates,
RmkvilIe, Maryland
Margaret Mattson, Ph.D., Special Assistant for Science, Office of the
Director, Division of Cancer Prevention and Control, National Cancer
Institute, Bethesda, Maryland


Chapter II. Carcirwgenesis Associated With Smokeless Tbbacco Use
William Blot, Ph.D., Chief, Biostatistics Branch, Division of Cancer
Etiology, National Cancer Institute, Bethesda, Maryland
Virginia L. Ems&, Ph.D., Associate Professor of Epidemiology,
University of California, San Francisco, California
Curtis Harris, M.D., Chief, Laboratory of Human Carcinogenesis,
Division of Cancer Etiology, National Cancer Institute, Bethesda,
Maryland
Stephen S. Hecht, Ph.D., Division of Chemical Carcinogenesis, Naylor
Dana Institute for Disease Prevention, American Health Foundation,
Valhalla, New York
Dietrich Hoffmann, Ph.D., Associate Director, Chemistry and Bio
chemistry, Naylor Dana Institute for Disease Prevention, American
Health Foundation, Valhalla, New York
Kenneth Rothman, Dr.P.H., Professor of Family and Community Medi-
cine, University of Massachusetts Medical School, Worcester,
Massachusetts

David Schottenfeld, M.D., Chief, Division of Epidemiology, Memorial
Sloan-Kettering Cancer Center, New York, New York
Steven R. Xannenbaum, PhD., Professor of Tbxicology and Food
Chemistry, Department of Applied Biological Sciences, Massachu-
setts Institute of %chnology, Cambridge, Massachusetts
David B. Thomas, M.D., Dr.P.H., Head, Program in Epidemiology,
Fred Hutchinson Cancer Research Center, Seattle, Washington
Deborah M. Winn, Ph.D., Epidemiologist, Survey Planning and Devel-
opment Branch National Center for Health Statistics, Hyattsville,
Maryland

Chapter III. Noncancerous and Precancerous Oral Health Effects
       Associated With Smokeless llbbacco Use
Stephen B. Corbin, D.D.S., M.P.H., Chief, Dental Disease Prevention
Activity, Center for Preventive Services, Centers for Disease Control,
RmkvilIe, Maryland
Lireka I? Joseph, Dr.P.H., Medical Radiation Specialist, Food and Drug
Administration, Rockvihe, Maryland
Dushanka Kleimnan, D.D.S., M.Sc.D., Special Assistant to the Asso
ciate Director for Program Coordination, Epidemiology and Oral
Disease Prevention Program, National Institute of Dental Research,
Bethesda, Maryland

Chapter IV. Nicotine Exposure: Pharmacokinetics, Addiction, and
     Other Physiologic Effects

Neal Benowitz, M.D., Associate Professor of Medicine, Chief of Clinical
Pharmacology and Experimental Therapeutics, University of Cali-
fornia, San Francisco, California
Anthony Biglan, PhD., Research Scientist, Oregon Research Institute,
Eugene, Oregon

xii


Jack Henningfield, Ph.D., Chief, Biology of Dependence and Abuse
Potential Assessment Laboratory, Addiction Research Center,
National Institute on Drug Abuse, Baltimore, Maryland
Margaret Mattson, PhD., Special Assistant for Science, Office of the
Director, Division of Cancer Prevention and Control, National Cancer
Institute, Bethesda, Maryland

The Advisory Committee and authors acknowledge with gratitude
the following distinguished scientists, physicians, and others who lent
their support in the development of this report by contributing critical
reviews of the manuscript or assisting in other ways:

John Bailar, M.D., Ph.D., Lecturer, Department of Biostatistics, Har-
vard School of Public Health, Boston, Massachusetts
Enriqueta C. Bond, PhD., Director, Division of Health Promotion and
Disease Prevention, Institute of Medicine, Washington, D.C.
Lester Breslow, M.D., M.P.H., Professor Emeritus, School of Public
Health, University of California, Los Angeles, California
David M. Burns, M.D., Associate Professor of Medicine, Division of
Pulmonary and Critical Care Medicine, University of California, San
Diego Medical Center, San Diego, California
Greg Connolly, D.M.D., M.P.H., Director, Division of Dental Health,
Massachusetts Department of Public Health Boston Massachusetts
D. Layten Davis, PhD., Director, University of Kentucky, Ylbbacco and
Health Research Institute, Lexington, Kentucky
Miriam Davis, PhD., Program Analyst, Office of Health Planning and
Evaluation, Office of the Assistant Secretary for Health, Washing-
ton, D.C.
Vincent T. DeVita, Jr., M.D., Director, National Cancer Institute,
Bethesda, Maryland
Joseph F. Fraumeni, Jr., M.D., Associate Director for Epidemiology
and Biostatistics, Division of Cancer Etiology, National Cancer Insti-
tute, Bethesda, Maryland

Thomas J. Glynn, PhD., Program Director for Smoking Research,
Division of Cancer Prevention and Control, National Cancer Insti-
tute, Bethesda, Maryland
Peter Greenwald, M.D., Dr.P.H., Director, Division of Cancer Preven-
tion and Control, National Cancer Institute, Bethesda, Maryland
Ellen R. Grits, PhD., Director, Division of Cancer Control, UCLA
Jonsson Comprehensive Cancer Center, Los Angeles, Cahfornia
Dianne G. Lindewall, Ph.D., Program Analyst, Office of Health Plan-
ning and Evaluation, Office of the Assistant Secretary for Health,
Washington, D.C.
Marilyn M. Massey, M.P.H., `Ikchnical Support Staff Coordinator for
the Advisory Committee, Senior Associate, Prospect Associates,
lbdwille, Maryland

. . .
XlJl


Gardner C. McMillan, M.D., Associate Director for Etiology, Arterio
sclerosis, and Hypertension, National Heart, Lung, and Blood Insti-
tute, Bethesda, Maryland
Jens J. Pindborg, D.D.S., Dr. Odont., Professor of Oral Pathology,
Royal Dental College, Copenhagen Panum Institute, Copenhagen
Denmark
John M. Pinney, Executive Director, Institute for the Study of Smoking
Behavior and Policy, John F. Kennedy School of Government, Har-
vard University, Cambridge, Massachusetts
Earl S. Polk&, Sc.D., President, Pollack Associates Ltd., Bethesda,
Maryland
Richard J. Riseberg, Chief Counsel United States Public Health Ser-
vice, Rochille, Maryland
Thomas L. Robertson, M.D., Chief, Cardiac Diseases Branch, National
Heart, Lung, and Blood Institute, Bethesda, Maryland
Beatrice A. Rouse, PhD., Epidemiologist, Division of Epidemiology
and Statistical Analysis, National Institute on Drug Abuse, Rock-
vilIe, Maryland
Donald R. Shopland, Acting Director, Office on Smoking and Health,
United States Public Health Service, Rockvile, Maryland
Sol Silverman Jr., M.A., D.D.S., Professor and Chairman of Oral Medi-
cine, University of California, San Francisco, California
Chester Slaughter, M.A., Deputy Regional Inspector General for Analy-
sis and Inspections, Office of the Inspector General DaIlas, Texas
K. W. Stephen, D.D.Sc., H.D.D.R.C.P.S., Head of Oral Medicine and
Pathology, University of Glasgow, Glasgow, Scotland
Ronald W. Wilson, M.A., Director, Division of Epidemiology and
Health Promotion, National Center for Health Statistics, Hyattsville,
Maryland
Ernst L. Wynder, M.D., President, American Health Foundation, New
York, New York
Mar& Zitans, M.&z., Program Analyst, Office of the Inspector General
Washington, D.C.
The Advisory Committee and authors also acknowledge several
organizations for their contributions in identifying relevant literature
and/or in offering critical reviews of the manuscript.
Institute of Medicine, National Academy of Sciences, for providing
through its Board on Health Promotion and Disease Prevention a cri-
tique of the Advisory Committee's review methods and drafts of the
report.
International Agency for Research on Cancer (IARC), Lyon, France, for
providing IARC Monograph No. 37 on the Evaluation of the Carcino
genie Risk of Chemicals to Humans: Tobacco Habits Other Than
Smoking Betel-Quid and Areca-Nut Chewing and Some Related
Nitrosammes, September 1985.


National Center for Health Statistics and National Institute on Drug
Abuse, for providing data on the prevalence and trends of smokeless
tobacco use in the United States.

Office on Smoking and Health, for bibliographic citations and other
documents pertinent to the literature review.
Smokeless Tobacco Council, Inc. (Michael J. Kerrigan, President), for
providing approximately 15,000 citations considered relevant by a
number of the smokeless tobacco companies, including the collection
of testimonies representing the smokeless tobacco industry's position
concerning the health consequences of smokeless tobacco.

The Advisory Committee and authors also acknowledge the contribu-
tions of the following staff members and others who assisted in the
preparation of the report:

Kathy Bauman, Editorial Assistant to the Deputy Director, Division of
Cancer Prevention and Control, National Cancer Institute, Bethesda,
Maryland

Julie Begtm, Research Assistant, Prospect Associates, Rockville,
Maryland

Barbara Clark, M.S., M.P.H., Technical Support Staff Coordinator for
Non-Cancer Oral Effects Experts, Prospect Associates, Rockvihe,
Maryland

Shelley Clark, Conference Coordinator, Prospect Associates, Rockvihe,
Maryland

Nancy Cowan Conference Coordinator, Prospect Associates, Rockvihe,
Maryland

Kathleen Edmunds, Library Besearch Assistant, Prospect Associates,
RockviUe, Maryland

Robyn Ertwine, Librarian-Information Specialist, Prospect Associates,
RockviNe, Maryland

Catherine Fisher, Secretary, Prospect Associates, Rockvihe, Maryland
Barbara Hayden, Secretary, Prospect Associates, Rockvihe, Maryland
Douglas Hunter, Library Assistant, Prospect Associates, Kockvihe,
Maryland
Karen Jacob, Editor, Prospect Associates, Rockvihe, Maryland
Margaret Johnson, `Typist, Prospect Associates, Rockville, Maryland
Mary Johnson, Typist, Prospect Associates, Rockvihe, Maryland
Virginia Knill, Typist, Prospect Associates, RockviIle, Maryland
Solomon Levy, M.P.H., Associate Director, Office of the Surgeon
General, Rockvihe, Maryland

Paula Margus, Library Research Assistant, Prospect Associates, Rock-
ville, Maryland

Nancy McCormick-Picket& M.A., %&nicsl Support Staff Coordinator
for Carcinogenesis Experts, Prospect Associates, Rockvihe, Maryland
Lee McPherson, Typist, Prospect Associates, Rockvihe, Maryland

xv


Robbie Morsel&, Library Assistant, Prospect Associates, Rockville,
Maryland
Elizabeth Mugge, Secretary to the Deputy Director of the Division of
Cancer Prevention and Control, National Cancer Institute, Bethesda,
Maryland
Arthur Nelson, Library Research Assistant, Prospect Associates,
Fhkville, Maryland

Ro NemethCoslett, Ph.D., Visiting Scientist, Biology of Dependence
and Abuse Potential Assessment Laboratory, Addiction Research
Center, National Institute on Drug Abuse, Baltimore, Maryland
Simon Plog, l)pist, Prospect Associates, Rockvihe, Maryland
Nancy Rudner, M.S.N., M.P.H., 7hchnicaI Support Staff Assistant,
Prospect Associates, Rockvihe, Maryland
Estelle Schwalb, `Ilxhnical Writer-Editor, Prospect Associates, Rock-
ville, Maryland
Barbara Shapiro, Editor, Prospect Associates, Rockville, Maryland
John Shea, Ph.D., Technical Writer-Editor, Prospect Associates, Rock-
ville, Maryland
Dorritt Silber, Secretary, Prospect Associates, Rockvihe, Maryland
Dori Steele, Proofreader, Prospect Associates, Rockville, Maryland
Deborah S. Swansburg, Program Officer, Institute of Medicine,
National Academy of Sciences, Washington, D.C.

Xvi


INTFlODlJC'TlON, OVERVIEW,
  AND CONCLUSIONS

DEVELOPMENT AND ORGANIZATION OF THE REPORT

This report from the Surgeon General's Advisory Committee on the
Health Consequences of Using Smokeless Tobacco represents the first
comprehensive assessment of the biomedical and behavioral literature
describing experimental and human evidence on the health conse
quences of using smokeless tobacco. The content of this report is the
work of numerous experts within the Department of Health and
Human Services as well as distinguished scientists outside the
organization.

Each chapter of the report was prepared based on manuscripts writ-
ten by scientists who are recognized for their understanding of the spe
cific content areas. Manuscripts were subjected to extensive peer
review by a large number of experts in the specific areas of interest.
The report includes a "Preface" that presents the essence of the entire
report and an "Introduction, Overview, and Conclusions." The body of
the report consists of the following four chapters:

o Chapter l-Prevalence and Trends of Smokeless Tobacco Use
       in the United States

o Chapter 2-Carcinogenesis Associated With
        Smokeless ?bbacco Use

o Chapter 3-Noncancerous and Precancerous Oral Health Effects
        Associated With Smokeless Tobacco Use

o Chapter 4-Nicotine Exposure: Pharmacokinetics, Addiction,
      and Other Physiologic Effects

HJSTORICAL PERSPECTIVE

The use of smokeless tobacco is a worldwide practice with numerous
variations in the nature of the product used as well as in the customs
associated with its use. In the United States, smokeless tobacco con-
sists of chewing tobacco and snuff. The predo minant mode of use of
these nonsmoked tobaccos is oral, although they may be placed in or
inhaled into the nasal cavity. Tobacco sniffing, however, has been and
remains a rare practice in the United States.

Xvii


Smokeless tobacco was used in the United States in the early 1600's
when snuff made its way to the Jamestown Colony in Virginia through
the efforts of John RoIfe in 1611(l). Evidence of tobacco chewing, how-
ever, was not found until a century later in 1704 (2).
The use of tobacco, including smokeless tobacco, has been controver-
sial since its introduction. In the past, tobacco use was considered by
some as beneficial As early as 3500 B.C., there are indications that
tobacco was an article of established value to the inhabitants of Mexico
and Peru. It appears that people who frequently Iacked sufficient food
alleviated their hunger pains by chewing tobacco (3). Smokeless tobacco
was also thought to have several medicinal uses. Among Native Ameri-
cans, for example, chewing tobacco was used to alleviate toothaches,
disinfect cuts, and relieve the effects of snake, spider, and insect bites (4).
Moreover, during the 19th and early 20th centuries in America, dental
snuff was advertised to relieve toothache pain; to cure neuralgia, bleed-
ing gums, and scurvy; and to preserve and whiten teeth and prevent
decay (1).
On the other hand, tobacco use historically has had numerous adver-
saries, inchiding the following (1):

o In 1590 in Japan tobacco was prohibited. Users lost their property
and were jaiIed

o King James VI of Scotland in the early 1600's was a strong anti-
smoking advocate who increased taxes on tobacco 4,000 percent in
an attempt to reduce the quantity imported to England.

o In 1633, the Sultan Murad IV of Turkey made any use of tobacco a
capital offense, punishable by death from hanging, beheading, or
starvation. He maintained that tobacco caused infertility and
reduced the fighting capabilities of his soldiers.

o The Russian Czar Michael Fedorovich, the first Romanov
(1613-1645). prohibited the sale of tobacco, stating that users
would be subjected to physical punishment and that persistent
users would be killed.

o A Chinese law in 1683 threatened that anyone possessing tobacco
would be beheaded.

o During the mid-1600's, Pope Urban VIII banned the use of snuff in
churches, and Pope Innocent X attacked its use by priests in the
Catholic Church.

o Other religious groups also banned snuff use: John Wesley, the
founder of Methodism, attacked its use in Ireland; the Mormons,
Seventh-Day Adventists, Parsees and Sikhs of India, Buddhist
monks of Korea, members of the Isai Li sect of China, and some
Ethiopian Christian sects forbade the use of tobacco.

  . . .
XVIU


o Frederick the Great, King of Prussia, prevented his mother, the
Dowager Queen of Prussia, from using snuff at his coronation in
1790.

o Louis XV, ruler of France from 1723 to 1774, banned snuff use
from the Court of France.

Scientific observations concerning the health effects of smokeless
tobacco use were first noted in 1761 by John Hill, a London physician
and botanist who reported five cases of polypuses, a "swelling in the
nostril that was hard, black and adherent with the symptoms of an open
cancer" (5). He concluded that nasal cancer could develop as a conse
quence of tobacco snuff use (sniffing).

Evidence that suggested a possible association between smokeless
tobacco use and oral conditions in North America and Europe was not
reported until 1915 when Abbe identified several tobacco chewers
among a series of oral cancer patients and commented that smokeless
tobacco use may be a risk factor for this cancer (6). In the late 1930's.
Ahblom observed in Sweden that more patients with buccal, gingival,
and `mandibular" cancers than with other cancers reported the use of
snuff or chewing tobacco (?L In the United States, case reports of oral
cancer among users of snuff or chewing tobacco appeared in the early
1940's (8). The first epidemiologic study of smokeless tobacco was not
conducted until the early 1950's (9). Since that time, several scientists
have described a pattern of increased risk of oral cancer among smoke
less tobacco users.

Investigations of other possible health effects of smokeless tobacco
use (e.g., noncancerous oral effects, addiction, and other physiologic
consequences) are more recent subjects of scientific inquiry that have
been undertaken primarily in the past two decades.

A brief review of the health consequences of smokeless tobacco was pre
sented in the 1979 Surgeon General's report on smoking and health (10).
Since that review, the results of additional studies addressing the role of
smokeless tobacco in health have become available and thus provide the
basis of this current comprehensive review.

REVIEW METHODS

For the purpose of evaluating the scientific evidence to be included in
this report, the Advisory Committee called upon the same criteria to
determine causality as have been used for a number of Surgeon
General's reports on smoking for the past two decades. The following
criteria were used as the primary guidelines for assessing whether any
associations between smokeless tobacco use and each of the disease
areas or health conditions under e xamination were likely to be causal in
Mtwe:

xix


o Consistency of the association-similar observations by multiple
investigators in different locations and situations, at different
times, and using different methods of study.

o Strength of the association-high ratio of disease rate for thepopu-
lation exposed to the suspected risk factor compared to the popula-
tion unexposed to the risk factor.

o Specificity of the association-associations with the exposure exist
for a specific or limited set of diseases, and associations with the
disease exist for a specific or limited set of exposures.

o Temporal relationship of the association-exposure to the
suspected etiologic factor precedes the disease.

o Coherence of the association-epidemiologic observations are con-
sonant with all else that is known about the disease.

In addition to these criteria, the general principles employed by the
International Agency for Resear& on Cancer (IARC)* in evaluating
the carcinogenic risk of chemicals or complex mixtures (table 1) were
used as needed to supplement the primary causation criteria (11).

The use of smokeless tobacco products in the United States was wide
spread until the end of the 19th century. With the advent of antispitting
laws, loss of social acceptability, and increased popularity of cigarette
smoking, its use declined rapidly in this century. However, recent na-
tional data indicate a resurgence in smokeless tobacco habits with more
than 12 million persons estimated as users of some form of smokeless
tobacco in 1985. An upward trend in use is emerging, particularly
among young males.

Given the evidence that smokeless tobacco is regaining popularity,
serious questions have been raised about its adverse health effects.
Most notably, this behavior has been linked to cancer, specifically, oral
cancer. Analytic epidemiologic studies now indicate that the use of oral
snuff increases the risk of oral cancer several fold and that among long-
term snuff dippers the excess risk of cancers of the cheek and gum may
reach nearly fiftyfold. This conclusion is consistent with the judgment
of a recent working group of the IARC, which assessed the carcinogenic
risk associated with tobacco habits other than smoking (11).

The conclusion that smokeless tobacco causes cancer results from
several lines of evidence: the presence of high levels of carcinogens in
smokeless tobacco; the metabolic conversion of products of smokeless

* The IARC was established in 1965 b
within the framework of the World Hea i the World Health Assembly as an inde
                  th Organization. It conducts a program o P K
                                     ndentl financed organization
                                         researc concentrating particu-
larly on the epidemiology of cancer and the study of potential carcinogens in the human environment.

xx


TABLE L-General F'rinciples in Evaluting
     Carcinogenic Risk of Chemicals or Complex Mixture8
      (Intemational Agency for R.4wal& on Cancer)

o  Evidence for carcinogenicity in experimental animals:
- Qualitative aspects:

(a) Experimental parameters under which chemical was tested.
(b)Consistency with which chemical shown to be ?????*???*???
(12) Spectrum of neoplastic response.
(d) Stage of tumor formation in which chemical involved.
(e) Role of modifying factors.
- Hormonal carcinogenesis.
- Complex mixtures.

- Quantitative aspects; increasing incidence of neoplasms with increasing
exposure.

o  Evidence for activity in short-term tests:
- Use of valid test system.
- Sufficiently wide dose range and duration of exposure to the agent and
  appropriate metabolic system employed in test.
- Use of appropriate controls.
- Specification of the purity of the compound, and in the case of complex
  mixtures, source and representativeness of sample tested.

o  Evidence of carcinogenicity in humans:
- For studies showing positive association:
  (a) Existence of no identifiable bias.
  (b) Possibility of positive confounding considered.
  (c) Association unlikely to be due to chance alone.
  (d) Association is strong.

(e) Existence of dose-response relationship.
- For studies showing no association:
(a) Existence of no identifiable negative bias.
(b) Possibility of negative wnfounding considered.
(c) Possible effects of misclassification of exposure or outcome have been
  ????????

tobacco into genotoxic agents; the consistency of the oral cancer-
smokeless tobacco association across epidemiologic investigations con-
ducted in diverse locations; the trend in increasiq oral cancer risk with
duration of exposure; the strength of the association with oral cancer
and the occurrence of the highest risks for cancers at the anatomic sites
where the tobacco expoams are the greatest.
In addition, a number of clinical observations and studies show an

association between smokeless tobacco use and some noncancerous and
precancerous oral health conditions. The development of a portion of
oral leukoplakias in both teenage and adult users can be attributed to
the use of smokeless tobacco. The risk of developing these leukoplakic
lesions increases with increased exposure, and a number of studies now
suggest that some snuff-induced leukoplakias can undergo transforma-


tion to dysplasia and further to carcinoma. The evidence concerning the
adverse health effects of smokeless tobacco use on other oral soft and
hard tissues is only suggestive at this time.
The magnitude of blood nicotine levels resulting from smokeless
tobacco use has been shown to be similar to that from cigarette smok-
ing. Therefore, the nicotinerelated health consequences of smoking
would also be expected to result from smokeless tobacco use. Given the
nicotine content of smokeless tobacco, the user's ability to sustain
elevated blood levels of nicotine, and the wellestablished data implicat-
ing nicotine as an addictive substance, it is reasonable to expect that
smokeless tobacco is capable of producing nicotine addiction in users.
There is also some suggestive evidence that nicotine may play a con-
tributory or supportive role in the development of coronary artery and
peripheral vascular disease, hypertension, peptic ulcer disease, and fetal
mortality and morbidity.
The conclusions in this report on the relationship between smokeless
tobacco use and cancer, noncancerous and precancerous oral conditions,
and addiction and dependence are substantially in agreement with
those published at a recent National Institutes of Health (NIH) Consen-
sus Development Conference on the Health Implications of Smokeless
TRhacco use (12).

CONCLUSIONS

Prevalence and Trends of Smokeless Tobacco Use
in the United States

1. Recent national data indicate that over 12 million persons used
some form of smokeless tobacco (chewing tobacco and snuff) in
1985 and that approximately 6 million used smokeless tobacco
weekly or more often. Use is increasing, particularly among
young males.

2. The highest rates of use are seen among teenage and young adult
males. A recent national survey indicates that 16 percent of
males between 12 and 25 years of age have used some form of
smokeless tobacco within the past year and that from onethird to
onehalf of these used smokeless tobacco at least once a week. Use
by females of all ages is consistently less than that of males;
about 2 percent have used smokeless tobacco in the last year.

3. State and local studies corroborate the national survey findings.
The prevalence of smokeless tobacco use by youth and young
adults varies widely by region, but use is not limited to a single re
gion. In several parts of the country, as many as 25 to 35 percent of
adolescent males have indicated cnrrent use of smokelees tobacco.

xxii


Carcinogenesis Associated With
Smokeless Tobacco Use

1. The scientific evidence is strong that the use of smokeless tobacco
can cause cancer in humans. The association between smokeless
tobacco use and cancer is strongest for cancers of the oral cavity.
2. Oral cancer has been shown to occur several times more fre-
quently among snuff dippers than among nontobacco users, and
the excess risk of cancers of the cheek and gum may reach nearly
fiftyfold among long-term snuff users.

3. Some investigations suggest that the use of chewing tobacco also
may increase the risk of oral cancer.

4. Evidence for an association between smokeless tobacco use and
cancers outside of the oral cavity in humans is sparse. Some
investigations suggest that smokeless tobacco users may face in-
creased risks of tumors of the upper aerodigestive tract, but
results are currently inconclusive.

5. Experimental investigations have revealed potent carcinogens in
snuff and chewing tobacco. These include nitrosamines, poly-
cyclic aromatic hydrocarbons, and radiation-emitting polonium
The tobacco-specific nitrosamines N-nitrosonornicotine and
4-(methylnitrosamino)-l-(3-pyridyl)-1-butanone have been
detected in smokeless tobacco at levels 100 times higher than the
regulated levels of other nitrosamines found in bacon, beer, and
other foods. Animals exposed to these tobacco-specific nitro
samines, at levels approximating those thought to be accumu-
lated during a human lifetime by daily smokeless tobacco users,
have developed an excess of a variety of tumors. The nitro
samines can be metabolized by target tissues to compounds that
can modify cellular genetic material.

6. Bioassays exposing animals to smokeless tobacco, however, have
generally shown little or no increased tumor production, although
some bioassays suggest that snuff may cause oral tumors when
testsd in animals that are infected with herpes simplex virus.

Noncancerous and Precancerous Oral Health Effects
Associated With Smokeless Tobacco Use

1. Smokeless tobacco use is responsible for the development of a por-
tion of oral leukoplakias in both teenage and adult users. The
degree to which the use of smokeless tobacco affects the oral hard
and soft tissues is variable depending on the site of action, type of
smokeless tobacco product used, frequency and duration of use,
predisposing factors, cofactors (such as smoking or concomitant
gingival disease), and other factors not yet determined.

  . . .
xxm


2. Dose response effects have been noted by a number of investiga-
tors. Longer use of smokeless tobacco results in a higher preva-
lence of leukoplakic lesions. Oral leukoplakias are commonly
found at the site of tobacco placement.

3. Some snuff-induced oral leukoplakic lesions have been noted
upon continued smokeless tobacco use to undergo transforma-
tion to a dysplastic state. A portion of these dysplastic lesions
can further develop into carcinomas of either a verrucous or
squamous cell variety.

4. Recent studies of the effects of smokeless tobacco use on gingival
and periodontal tissues have resulted in equivocal findings. While
gingival recession is a common outcome from use, gingivitis may
or may not occur. Because longitudinal data are not available, the
role of smokeless tobacco in the development and progression of
gingivitis or periodontitis has not been confirmed.

5. The evidence concerning the effects of smokeless tobacco use on
the salivary glands is inconclusive.

6. Negative health effects on the teeth from smokeless tobacco use
are suspected but unconfirmed. Present evidence, albeit sparse,
suggests that the combination of smokeless tobacco use in individ-
uals with existing gingivitis may increase the prevalence of dental
caries compared with nonusers without concomitant gingivitis.
Reports of tooth abrasion or staining have not been substantiated
through controlled studies; only case reports are available.

Nicotine Exposure: Pharmacokinetics, Addiction,
and Other Physiologic Effects
  1. The use of smokeless tobacco products can lead to nicotine depen-
   dence or addiction.

2. An examination of the pharmacokinetics of nicotine (i.e., nicotine
absorption, distribution, and elimination) resulting from smoking
and smokeless tobacco use indicates that the magnitude of nico-
tine exposure is similar for both.

3. Despite the complexities of tobacco smoke self-administration,
systematic analysis has confirmed that the resulting addiction is
similar to that produced and maintained by other addictive drugs
in both humans and animals. Animals can learn to discriminate
nicotine from other substances because of its effects on the cen-
tral nervous system. These effects are related to the dose and rate
of administration, as is also the case with other drugs of abuse.

4. It has been shown that nicotine functions as a reinforcer under a
variety of conditions. It has been confirmed that nicotine can

xxiv


function in all of the capacities that characterize a drug with a
liability to widespread abuse. Additionally, as is the case with
most other drugs of abuse, nicotine produces effects in the user
that are considered desirable to the user. These effects are caused
by the nicotine and not simply by the vehicle of delivery (tobacco
or tobacco smoke).

5. Nicotine is similar in all critical measures to prototypic drugs of
abuse such as morphine and cocaine. The methods and criteria
used to establish these similarities are identical to those used for
other drugs suspected of having the potential to produce abuse and
physiologic dependence. Specifically, nicotine is psychoactive,
producing transient dose-related changes in mood and feeling. It
is a euphoriant that produces doserelated increases in scores on
standard measures of euphoria. It is a reinforcer (or reward) in
both human and animal intravenous self-administration para-
digms, functioning as do other drugs of abuse. Additionally, nice
tine through smoking produces the same effects, and it causes
neuroadaptation leading to tolerance and physiologic depen-
dence. Taken together, these results confirm the hypothesis that
the role of nicotine in the compulsive use of tobacco is the same as
the role of morphine in the compulsive use of opium derivatives or
of cocaine in the compulsive use of coca derivatives.

6. The evidence that smokeless tobacco is addicting includes the
pharmacologic role of nicotine dose in regulating tobacco intake;
the commonalities between nicotine and other prototypic
dependenceproducing substances; the abuse liability and depen-
dence potential of nicotine; and the direct, albeit limited at present,
evidence that orally delivered nicotine retains the characteristics of
an addictive drug.

7. Several other characteristics of tobacco products in general, in-
cluding smokeless tobacco, may function to enhance further the
number of persons who are afflicted by nicotine dependence:
nicotinedelivering products are widely available and relatively
inexpensive; and the self-administration of such products is legal,
relatively well tolerated by society, and produces minimal d&-up-
tion to cognitive and behavioral performance. Nicotine produces
a variety of individual-specific therapeutic actions such as mood
and performance enhancement; and the brief effects of nicotine
ensure that conditioning occurs, because the behavior is associ-
ated with numerous concomitant environmental stimuli.
8. All commonly marketed and consumed smokeless tobacco prod-
ucts contain substantial quantities of nicotine. The nicotine is
delivered to the central nervous system in addicting quantities
when used in the fashion that each form is commonly used (or as
recommended in smokeless tobacco marketing campaigns).

XXV


9. Since the exposure to nicotine from smokeless tobacco is similar
in magnitude to nicotine exposure from cigarette smoking, the
health coIlSequences of smoking that are caused by nicotine also
would be expected to be hazards of smokeless tobacco use. Areas
of particular concern in which nicotine may play a contributory or
supportive role in the pathogenesis of disease include coronary
artery and peripheral vascular disease, hypertension, peptic ulcer
disease, and fetal mortality and morbidity.

REFERENCES

(1) Christen, A.G., Swanson, B.Z., Glover, E.D., and Henderson, A.H.
Smokeless tobacco: The folkIore and social history of snuffing, sneez-
ing, dipping, and chewing. J. Am. Dent. Assoc. 105: 821829, 1982.
(2) Gottsegen, J.J. Tobacco. A Study of Its Consumption in the United
States. New York, Pitman, 1940, p. 3.
(3) Voges, E. The pleasures of tobacco-How it ah began and the whole
story. Tobacco J. Int. 1: 80-82, 1984.
(4) Axton, W.F. Tobacco and Kentucky. Lexington, University Press of
Kentucky, 1975, pp. 8, 25, 58-59.

(5) Redmond, D.E. Tobacco and cancer: The first clinical report, 1761. N.
Engl. J. Med. 282: 18-23, 1970.

(6) Abbe, R. Cancer of the mouth. New York Med. J. 102: l-2,1915.
(7) Ahblom, H.E. Predisposing factors for epitheliomas of the oral cavity,
larynx, pharynx, and esophagus. Acta Radial. 18: 163-185, 1937 (in
Swedish).

(8) FriedeII, H.L.. and Rosenthal, L.M. The etiologic role of chewing
  tobacco in cancer of the mouth. JAMA 116: 2130-2135, 1941.
(9) Moore, G.E., Bissinger, L.L., and ProehI, E.C. Tobacco and intraoral
  cancer. Surg. Forum 3: 685-688, 1952.
(10) U.S. Public Health Service. Smoking and Health. A Report of the
  Surgeon General. Department of Health, Education, and Welfare,
  Public Health Service, Office of the Assistant Secretary for Health, Of-
  fice on Smoking and Health (DHEW Publication No. PHS 79-50066).
  Washington, D.C.. U.S. Government Printing Office, 1979, pp. 13-38 to
  13-41.

(11) International Agency for Research on Cancer. Tobacco habits other
  than smoking: Betel-quid and areca-nut chewing and some related
  nitrosamines. IARC Monogr. 37: 291,1985.
(12) National Institutes of Health. Consensus Development Conference
  Statement on the Health Implications of Smokeless Tobacco Use,
  January 13-15, 1986.

xxvi


Chapter 1.

PREVALENCE AND TRENDS OF
SMOKELESS TOBACCO USE
  IN THE UNED STATES


CONTENTS

Introduction ..................................... ...5


Product Characteristics. .............................. .5

l'kendsinProductionandSaIes  ......................... .5
Categories of Products ............................ .7
Tbmporallkends ............................... ...7

PendsinSeIf-ReportedUse: SurveyData. ............... .7
National Survey Data ............................. .7
StateandLocaISurveyData  ...................... .15

Conclusions........... . ..24

ResearchNeeds.....................................25

References.........................................26

3


INTRODUCTION

This chapter defines the various forms of smokeless tobacco that are
used in the United States and e xamines the data that pertain to trends
in prevalence and patterns of use. ?kends in smokeless tobacco produc-
tion and sales and self-reported use are considered. Methodological con-
siderations are discussed and research needs are identified.
Tobacco was used by pre-Columbian American Indians in smokeless
forms as well as smoked (1). Cultivated by American colonists, tobacco
became a major commodity in trade with Europe. Until the end of the
19th century, the use of smokeless tobacco products was widespread in
the United States. Its use declined rapidly in this century with the
advent of antispitting laws, loss of social acceptability, and increased
popularity of cigarette smoking (1,2). Use was primarily confined to
rutd and agricultural areas and to occupational settings where smok-
ing was not aIlowed, such as mining and some industries (3,4). In the
Southeastern United States, especially in rural areas, oral use of dry
snuff remained pop&r among women (5,6).

PRODUCT CHARACTERISTICS

T&lay, smokeless tobacco is produced in two general forms: chewing
tobacco and snuff (7-10). Chewing tobacco is chewed or held in the cheek
or lower lip. Three primary types of chewing tobacco are marketed:
looseleaf, plug, and twist. Snuff has a much finer consistency than
chewing tobacco and is held in place in the mouth without chewing. It is
marketed in both dry and moist forms. Although smokeless tobacco is
not subject to combustion and is usually used orally in the United
States, products differ with regard to several factors, including type of
tobacco plant used, parts of the tobacco plant used, method of curing,
moisture content, and additives. For example, looseleaf chewing
tobacco is made from aircured, cigar-type leaves from tobacco that is
grown in Pennsylvania and Wisconsin In contrast, dry snuff is made
primarily from firecured dark tobacco that is grown in Kentucky and
`Ibnnessee. Plug tobacco and snuff come in dry and moist forms. Many
smokeless tobacco products are sweetened with sugar or molasses.
Many are flavored; licorice is a common additive for chewing tobacco,
while mint and wintergreen often are used to flavor snuff. able 1
describes the types of smokeless tobacco and how they are used and
packaged (7-101.

TRENDS IN PRODUCTION AND SALES

United States Department of Agriculture (USDA) records on the
annual production and sales of smokeless tobacco serve as indicators of
the population's consumption Changes in consumption can be inferred
from changes in production and sales. Because sales figures closely
resemble those for production, only production will be reported.

5


0.J   TABLE l.-Characteristics of Smokeless Tobacco Products

Product       Description

How used

Packaging*

Plug

`I\vist

CHEWING TOBACCO

Made from airwred. cigar leal tobaccos of I'ennsylvan~a
and Wisconsin. Consists 111 stripped and procrssed Lobacco
leaves. The leaves are sttvnmtul. rut. or granulated and are
loosely packed to form small strips of shredded tobacco.
Most brands are sweetened and flavortxl with licorice.

Made from enriched tobacco leaves (I~urlry and bright
tobacco and cigar tobacco) or fragments wrapped in fine
tobacco and pressed into bricks. May be firm (less than 15
percent moisture) or m&l (15 percent or greater
moisture). Most plug tohacro is swwlened and flavored
with licorice.

Handmade of dark, air-cured leaf tobacco treated with a
tarlike tobawo leaf extract and twisted into strands that
are dried. Majority is sold without flavoring and
sW~La"ars.

A piece of tobacco. 314 Lo 1 inch in
diameter, is tucked between the gum and
jaw, usually Lo the back of the mouth.

Pouch. typically 3 ounces. A few brands
market a 1.5-ounce pouch.

Chewed or held in the cheek or lower lip.
May be held in the mouth for several
hours.

A compressed brick or flat block wrapped
inside natural tobacco leaves. Packaged
in clear plastic. Packages range from 7 Lo
13 ounces. Also sold by the piece.

Similar to plug.

A pliable but dry rope. Sold by the piece,
packaged in plastic bags. No standard
weight. Sold in small (approximately l-2
ounces) and larger sizes based on the
number of leaves in the twist.

SNUFF

Moist




Dry

Made from air-cured and fire-cured tobacco. Consists of
tobacco sLems and leaves that are processcld into fine par-
ticks or strips. Some products are flavored. Has a
moisture content of up to 50 percent.
Most dry snuff is made from fire-curtd tobaccos of Ken-
tucky and Tennessee. After initial curing. the tobacco is
fermented further and processed into a dry powdered
form. Products vary in strength and flavoring. tienerally
has a moisture content of less than 10 percent.

A small amount ("pinch") is placed
between the lip or cheek and gum and is
typically held for 30 minutes or longer
per pinch.
Same as moist snuff. May also be sniffed.

Cans and plastic containers. typically 1.2
ounces.



Metal cans or glass containers, vary from
1.15 to 7 ounces per container.

* Product weight Iincludes moisture).


Categories of Products

The USDA reports production and sales by product category (i.e.,
chewing tobacco and snuff). The definitions of categories changed in
198 1. Prior to 198 1, total figures for chewing tobacco were derived by
summing data for the subcategories of plug, twist, looseleaf, and fine
cut; snuff was a separate category. However, finecut tobacco is used in
moist snuff. `Ih reflect this fact, after 1981 USDA shifted fine-cut from
the category of chewing tobacco to moist snuff. Tb observe and clarify
temporal trends for the purposes of this review, the data presented in
figure 1 reflect a uniform category system across years. In these
records, finecut tobacco is counted consistently as snuff (11-17).

Temporal Trends

Figure 1 depicts temporal trends in the quantities of smokeless tobacco
that were manufactured in the United States from 1961 to 1985. Be
tween 1944 and 1968, total smokeless tobacco production declined 38.4
percent from 150.2 to 92.5 miI.Iion pounds. Subsequent increases in pro
duction reached 135.6 rniIIion pounds in 1985.
Between 1970 and 1985, total snuff production increased 56 percent
from 31.3 to 48.7 million pounds. This increase was due to changes in
the production of moist snuff; the manufacture of dry snuff dechned (3).
The difference in trends in the production of moist and dry snuff is
shown in figure 1 for the years 1981 through 1985. Separate production
data are not available for the two types of snuff prior to 1981. Between
1970 and 1981, however, the production of finecut tobacco, used in the
manufacture of some moist snuff, increased threefold from 4.8 to 15.2
miIIion pounds.

Between 1970 and 1985, the production of chewing tobacco increased
36 percent from 63.9 to 86.9 miIIion pounds. This increase was due to
the production of looseleaf tobacco, which increased 87.3 percent from
39.5 to 74.0 mihion pounds. The production of plug and twist tobacco
declined during this period.

National Survey Data

National data from 1964 to 1985 are available from eight different na-
tional probability surveys and a national survey of college students.
The majority of the data pertain to persons over the age of 17. The prin-
cipal characteristics of these surveys are shown in table 2.

Office on Smoking and He&h Surveys
Early data on the use of chewing tobacco and snuff are available from
the 1964.1966.1970, and 1975 Adult Use of Tobacco Surveys that were


FIGURE l.-Manufacturing lhdsz Quantities of
      Smokeless `Ibbacco Mamdactured in the United States
     From 1961 to 1985 Expressed in Million Pounds

   o ?
??
??
? ? ?


TABLE 2.-National Prevalence of Smokeless Tobacco Use: Data Sources

Number of

survey            *          Date   Respondents

Respondents/
Households

Products

Questions

Office on Smoking
and Health

Office on Smoking
and Health

Office on Smoking
and Health

Oifice on Smoking
and Health

National Health Interview
Survey Supplement
(National Center for
Health Statistics)

Simmons Study of
Media Markets,
Simmons Market
Research Bureau, Inc.

Simmons National
College Study,
Simmons Market
Research Bureau, Inc

Personal
Interview

Personal
Interview
Telephone

`IbIephone


Personal
Interview
Including
Proxy
Questionnaire

Questionnaire

Current Population Survey   Personal
Supplement-Census Bureau Interview
for Office on Smoking    I"chJdi"g
and Health          Proxy

NIDA Household        P~sO"Ed
Survey              Interview

1964   Adults L 21     5,794

1966

Adults L 21


Adults 2 21


Adults > 21


Persons 2 17

5,770

1970

5,200

1975

1970

12.000


77,ooo/
37.ooo

1980
1981
1982
1983
1984
1985

1983

1985

Adults 2 18

15,ooo-
19,ooo

Cdegs
Students
2 18

2,011-
2,373

1985   Persons 1 16

12o.o00/      Snuff and Chewing
58,000      Tobacco Separately

1985   Persons > 12    8,ooO

Snuff and Chewing
Tbbacco Separately
Snuff and Chewing
Tobacco Separately
Snuff and Chewing
Tbbacco Separately
Snuff and Chewing
-Ibbacco separately
Snuff and Chewing
lbbacco Separately

Snuff only

Snuff only

Snuff and        "On the average. in the past 12 months,
Chewing        how often have you used chewing tobacco
`Ibbacco Combined     or snuff or other smokeless tobacco?"

"Have you ever used-at aII regularly?"
"Do you use-now?"
"Have you ever used-at aII regularly?"
"Do you use-now?"
"Have you ever used-at all regularly?"
"Do you use-now?"
"Have you ever used-at alI regularly?"
"Do you use-now?"

Dol?S      presently use any other
form of smokeless tobacco, such as snuff or
chewing tobacco?

1980 to 1983 "Do you use it yourself-
snuff (smokeless tobacco)?"
1984 to 1985 "Do you yourself use any of the
following tobacco products?" Snuff (ST)
listed as an option.

"Please mark which of the items listed below
you yourself use."

Snuff (smokeless tobacco) listed as a" option.

Does     presently use any other form
of tobacco. such as snuff or chewing tobacco?
What other forms of tobacco does
presently use?


TABLE 3.-Use of Smokeless Tobacco in the United States by
     Individuals Over 21 Years of Age*

Percentage of Users

                         Males            Females

Use Catesrw            1964  l!x6  1970  1975  1964  1966  1970  1915

Now Use Snuff             2.0   3.1   2.9   2.5   2.0   2.1   1.4   1.3
Used to Use Snuff           3.6   3.9   4.2   4.0   0.9   1.0   1.1   1.1
Have Ever Used Snuff t       5.7   7.2   7.1   6.4   2.9   3.1   2.6   2.4
Now Use Chewing Tobacco      5.1   7.1   5.6   4.9   0.5   0.4   0.6   0.6
Used to Use Chewing mbacco   12.0  13.2  19.1  16.1   1.0   1.1   1.8   1.2
Have Ever Used
Chewing Tobaccot         17.2  20.5  24.7  21.0   1.5   1.5   2.4   1.8

* "Use" not further defined with respect to frequency.
t Includes those who used to use. but did not state if they used it currently.
Source: National Clearinghouse on Smoking and Health

conducted by the National Clearinghouse for Smoking and Health, cur-
rently the Office on Smoking and Health (OSH) (18-20). National prob
ability samples of 5,700 to 12.000 individuals over the age of 21 from
randomly selected households were interviewed by telephone regarding
the use of tobacco products. Between 1964 and 1975, the prevalence of
smokeless tobacco use remained fairly stable. Results are summ&zed
in table 3. Three patterns in these data may be noted:

o Less than 5 percent of the population reported using smokeless
tobacco.

o Nationally, use was higher among males than females.

o Among males, the prevalence of use of chewing tobacco was higher
than that for snuff.

National Health Interview Survey

In 1970, the National Center for Health Statistics included a question
on current use of snuff and chewing tobacco in its National Health
Interview Survey (NHIS) (21). One respondent per household provided
information on alI household members age 17 and older. Data were col-
lected on approximately 77,000 persons in 37,000 households. Esti-
mates indicate that 1.4 percent of males used snuff and 3.8 percent used
chewing tobacco (table 4).

Simmons Market Research Bureau, Inc.
National probability data that were coIIected annuaIIy from 1980

through 1985 for the Simmons Study of Media and Markets provide
estimates of the prevalence of snuff use among adults who were 18
years of age or older. Sample size ranged from 15,000 to 19,000. Data
are     ed in table 5 for the years 1980 to 1985. The prevalence

10


TABLE 4.-Prevalence of the Use of Snuff and Chewing `lbbncco
     Among Malee by Age, 1970 NHIS and 1985 CPS Surveys*

1970 HIS              1985 CPS

Product

Snuff







Chewing
Tobacco

Age

17-19
20-29
30-39
40-49
50+

Total

17-19
20-29
30-39
40-49
50+

lbtal

Percentage
of usf!m


  0.3
  0.6
  0.7
  1.2
  2.7

  1.4

  1.2
  1.9
  2.8
  3.0
  6.5

  3.8

Age

16-19
20-29
30-39
40-49
50+

?btal

16-19
20-29
30-39
40-49
50+

mal

Percentage
of uaem

  2.9
  2.7
  1.8
  1.5
  1.4

  1.9

  3.0
  4.2
  3.7
  3.3
  4.2

  3.9

o "Use" *?? further defined with respect to frequency.
Sources: National Center for Health Statistics. National Health Interview Survey, 1970 (unpublished). Office on
SmoLing and Health, Current Population Survey. 1985 (unpubtiahedl.

TABLE B.-National Prevalence of Current Use of Snuff by
     Gender, Age, and Race for 19&o Through 1985*

                   Percentage of Ufsera

Sample

1980     1961     1982     1963     1984     1985

Total        1.6      2.2      2.6      2.3      1.9      1.9

Gender
Males
Females

2.4      3.7      4.2      3.8      3.0      3.2
0.8      0.8      1.1      0.9      1.0      0.7

Ali!=
18-24
25-34
35-44
45-54
55-64
2 65

1.4      2.6      4.3      3.5      3.2      2.8
2.5      2.8      3.1      3.0      2.0      2.1
1.07     1.3      1.6      1.8      1.5      1.0
1.37     1.3     1.47    1.07    1.17     1.5
1.2t     1.7      1.7      2.3     1.1t     1.3
1.67     2.8      2.6      1.4      2.5      2.4

Race
Black
White
Other

2.3t    1.6t     3.0      2.9      2.9      2.4
1.5      2.2      2.6      2.3      1.9      1.9
1.97    1.47    1.17     NA     0.4t     1.2

o Adults defined as individuals over 18 years of age. Use not further defined with respect to frequency.
t Number of cases too small for reliable estimates.
Source: Simmons Market Reaemch Bureau. Inc.. Study of ????? and Markets. 1980.1985.

11


TABLE 6.-Prevalence of Snuff Use Among College Students
     18 Years of Age or Older by Gender and Year*

Percentage of Users

Sample

1983             1986

Total

Gender
Males
Females

Race
Black
White
Other

2.7               3.5


5.4               6.7
0.17            0.2f


1.5t            1.4-f
5.1               3.6
4.97            4.37

o Current use; frequency of "se not specified.
t Projection relatively unstable because of small sample.
Source: Simmons Market Research Bureau, Inc.. Simmons National College Study, 1983 and 1985

rate for "current use" of snuff was 2.4 percent for males in 1980 and 0.8
percent for females. Rates for males peaked at 4.2 percent in 1982 and
were 3.2 percent in 1985. Since 1982, the highest rates of use have con-
sistently been observed in the age group 18 to 24 years old. Compara-
tively higher rates of use were also observed in the age groups 25 to 34
years old and over age 65 (22.

The Simmons National College Study reports data from a probability
sample of full-time students 18 years or older who were attending
baccalaureategranting colleges and universities in the coterminous
United States. In 1983, 2,011 students were sampled, and 2,373
students were sampled in 1985. Five to 7 percent of males indicated use
of snuff compared to 0.2 percent of females (table 6). The prevalence rate
among male students exceeded that of the general adult male popula-
tion (tables 5 and 6). In 1985, prevalence among college males was twice
that of other adult males, while the rate for college women was less than
onethird that among the general adult female population. The com-
bined prevalence for male and female college students (3.5 percent) was
very similar to that for 18- to 24yearolds in the general population (2.8
percent) (tables 5 and 6) (23).

Current Population Survey

In the fall of 1985, the Census Bureau collected health information on
approximately 120,000 persons in 58,000 households in its Current
Population Survey (CPS) (24). OSH sponsored a supplement to this
survey, which included a question on current use of snuff and chewing
tobacco. One respondent per household provided information on all
members age 16 and older. Provisional estimates of smokeless tobacco
use indicate that 1.9 percent of males used snuff and 3.9 percent used
chewing tobacco (table 4).

12


TABLEI 7.-National Prevalence of Smokeless `Ibbaccu Use by
     Adult Status aud Sex, NIDA Sample, 198!5*

Percentage. of Users

                   Males                Females

Use Category      12OYears     2 21 Years     I 20 Years    r21Years

Used in Past Year      16          11          2           2
Used Formerly         4          7          2           2

Never Used          79         82          96         96

o Preliminary estimates not adJusted for oversampling of blacks and Hispamcs.
Source: National Institute on Drug Abuse, 1985 Natmnal Household Survey on Drug Abuse Preliminary results
presented at the NIH Consensus Development Conference on the Health Implications of Smokeless lbbacco Use.
January 1986.

TABLE 8.-Recency of Smokeless Tobacco Use by
     Sex and Age Group*

Percentage of Users by Age Groups

           12-17        l&25        26-3s        40-t

Use Categom Males Females Males Females Males Females Males Females

Usedin
Past Year    16      1     16      1     10      1     8     3
Used
Formerly     4      2      7      1      5      1      8      2
Never Used   80     97     77     98     85     98     84     95

*   
P&mmary estimates not adjusted for oversampling of blacks and Hispanics
Source: National Institute on Dtug Abuse, 1985 National Household Survey on Drug Abuse. Preliminary results
t; resented at the NIH Consensus Development Conference on the Health Implications of Smokeless Tobacco Use.
anuary 1986.

National Institute on Drug Abuse Housebold Survey
The recently completed 1985 National Household Survey on Drug
Use provides the national probability data on current use and correlates
of use of smokeless tobacco by youth It is the eighth in a series of na-
tional probability surveys conducted among household residents in the
coterminous United States by the National Institute on Drug Abuse
(NIDA). Data are collected on the use and adverse consequences that
are associated with 11 drugs or drug classes. The 1985 survey over-
sampled for blacks and Hispanics and younger age groups. The total
sample consists of approximately 8,000 facet-o-face interviews. The
data presented here are based on a prehminary analysis of 4,564 inter-
views. provisional estimates are presented in tables 7 through 9.

Sixteen percent of males under the age of 21 reported using chewing
tobacco or snuff within the last year, in contrast to 11 percent of older
males (table 7). The decline in older age groups is seen more clearly when
narrower age categories are used (table 8). An estimate of the preva-
lence of weekly use may be obtained by combining the use frequency

13


TABLE 9.--Frequency of Smokeless Tobacco Use in Past Year*

Percentage of Users

Past Year Use of
Smokeless Tobacco

Age Groups for Males
12-17 18% 2&39 40+

Males and Females
Age 12 and Above

Most Days/Week             3     7     5     4        2
1 or 2 Days/Week            2     1      1     1        1
1 or More Days/Week         5     8     6     5        3
3-51 Days/Year               5     5     3     3        2

1-2 Days/Year               6     3     2     1        2

Not in Past Year              4     7     5     8        3
Have `Itied              20 23 15 16       10
Never                 80 77 85 84       90

o Prelmnary estunates not adJusted for oversampling of blacks and Hispanics.
Source National Institute on Drug Abuse. 1985 National Household Survey on Drug Abuse. Preliminary results
presented ar. the N IH Consensus Development Conference on the Health Implications of Smokeless Tobacco Use.
January 1986.

categories of "most days a week" and "1 or 2 days a week" (table 9). Use
at least once a week peaks in the 1% to 25year-old age groups at 8 per-
cent. As in previous surveys, the use among females was consistently
much lower than among males. Responses suggest slightly higher rates
of use among women 40 years of age and older than among younger
women (table 8) (25).

Discussion of National Survey Data

Despite varying methodologies among the national surveys (table 2),
sufficient commonalities permit mean@ful comparisons. The 1970 and
1975 OSH surveys and the 1980 to 1985 Simmons Study of Media and
Markets indicate that the use of snuff by adult males remained con-
stant within a range of 3 to 4 percent. Use by adult females also re-
mained constant at about 1 percent. During this same l&year period,
the population over the age of 18 increased 32 percent from 133.5
million to 175.8 million (26). The production of all forms of smokeless
tobacco increased 42 percent from 95.2 to 135.6 million pounds, and the
production of finecut/moist snuff tripled. This may indicate the
emergence of a new population of users.

The 1970 NHIS and the 1985 CPS both relied on the use of proxy re
spondents. Estimates of smokeless tobacco use are likely to be lower
than the actual population prevalence because respondents may not
always be aware of smokeless tobacco use by other members of the
household. In fact, in 1970, the NHIS estimated that 1.4 percent of
males used snuff and 3.8 percent used chewing tobacco. In the same
year, the OSH Adult Survey, which did not use proxy respondents, pro
vided corresponding estimates of 3 and 6 percent. Similarly, the CPS
estimates that 1.9 percent of males used snuff in 1985, while the Sim-
mons Study of Media and Markets estimates 3.2 percent.

14


However, comparisons between the 1970 NHIS and the 1985 CPS for
the purpose of e xamining trends are appropriate. They suggest little
change in the overall rate of adult male use of smokeless tobacco but
indicate a marked change in the age distribution of users (table 4). In
1970, the use of smokeless tobacco was most common among older
men; in 1985, the prevalence in the younger age groups had greatly
increased.

Both the Simmons Study of Media and Markets and the NIDA
survey show the highest rates of use among young adults ages 18 to 24.
The Simmons National College Study indicates that male college
students are as likely to use snuff as are other 18- to 24-year-olds. The
Simmons data also show a slight elevation in prevalence among persons
over the age of 65, which reflects the age distribution of traditional
users of smokeless tobacco.

If the NIDA prevalence estimates are applied to current population
figures (261, there are at present over 12 million persons in the United
States ages 12 and older who have used some form of smokeless tobacco
in the past year. Three million are under the age of 21, and 1.7 milhon of
these are males 12 to 17 years old. An estimated 6 million persons use
smokeless tobacco at least weekly. Of these, 0.5 million are males ages
12 to 17; 1.3 million are males ages 18 to 25; and approximately 780,000
are females.

The 1980 to 1985 Simmons Study of Media and Markets estimated
that 2 to 4 million persons over the age of 18 were users of snuff. Of
these, 0.6 to 1.2 million were between the ages of 18 and 24.
able 10 summar%es data on the prevalence of smokeless tobacco use
by region from three national surveys conducted in 1985. Among these
adult samples, use was highest in the South and lowest in the North-
east, with the West and North Central/Midwest falling in between.

These surveys provide self-report data only; no direct validation at-
tempts were made. Because no strong social sanctions regarding
smokeless tobacco use exist for adults, systematic misrepresentation
by them is unlikely. However, under the conditions of a personal inter-
view, as used in the NIDA study, adolescents would be more likely to
underreport than over-report their use of smokeless tobacco. In addi-
tion, the prehminary estimates from the NIDA survey have not been
adjusted for oversampling of blacks and Hispanics. In this sample,
blacks and Hispanics reported less smokeless tobacco use than whites,
and their over-representation would result in underestimates of national
prevalence.

State and Local Survey Data
State and local surveys provide much of the information after 1980 on
the use of smokeless tobacco. Since most of these surveys were con-
ducted in schools, often motivated by apparent increases in students'

15


TABLE lo.-Prevalence of Smokeless Tobacco Use by
      census Region, 1985

Prevalence Category

      Percentage Reporting Use
Northeast North Central South

West

CPS
Chewing Tobacco
Snuff

Simmons
Snuff

NIDA*
(Snuff and/or chewing
tobacco)
Weekly Use or
  More Often
Any Use in Past Year

1.6        3.7        7.0        3.9
1.2        2.3        3.1        1.6



1.5        1.3        2.9        1.3








1.0        2.0        5.0        4.0
4.0        6.0        8.0        9.0

* Preliminary estimates not adjusted for age and race
Sources: Office on Smoking and Hex&b. Current Population Survey. 1985 iunpublished). Simmons Market
Research Bureau. Inc., Study of Media and Markets. 1980-1985. National Institute on Drag Abuse, 1965 House-
hold Survey on Drug Abuse. Preliminary results presented at the NIH Consensus Develqxnent Conference on the
Health Implications of Smokeless lbbscco Use, January 1986.

use of smokeless tobacco products, there may be a selection bias.
However, the large and growing number of reports and the wide
geographic coverage support the conclusion that smokeless tobacco use
is not a localized phenomenon, Indeed, the consistency of such data sug-
gests that smokeless tobacco has become a product that is used by
large numbers of teenage and young adult males.

Adult Use

Several reports provide a tentative profile of local usage patterns of
smokeless tobacco among adults. In 1979, tobacco use information was
collated from 4,282 men between the ages of 21 and 84 in 10 geographic
areas as part of the National Bladder Cancer Study, a population-based
case control study (27). The overall prevalence for having "ever used
snuff for 6 months or more" among the control subjects (randomly
selected from the general population) was 5 percent; for chewing to
bacco, the corresponding figure was 12 percent. A breakdown by age
indicated much more use of smokeless products by older men than
younger men (table 11).

Glover and his colleagues conducted a random sample telephone
survey of 280 persons in Pitt County, North Carolina (28). A user was
defined as a person who answered "yes" to the question, "Do you dip or
chew tobacco?" Forty percent of males and 9 percent of females
answered positively. High rates of use are probably not a new phenome
non since. there is a tradition of smokeless tobacco use among both
sexes in this area, and tobacco is a major agricultural product,.

16


TABLE Il.--prevalence of Snuff and Chewing Tobacco Use by
     Adult Males in 10 Geographic Areaa

Percentage Reporting Ever Used

Sample                n        Snuff       Chewing lbbacco

All Men             4.282         5               12

Age
21-44
45-64
65-84

240          0               2
1,653          3                6
2,389          7               16

Area of Residence
Atlanta
Connecticut
Detroit
Iowa
New Jersey
New Mexico
New Orleans
San Francisco
Seattle
Utah

186          8               23
654          4               12
355          8               20
552         12               14
1.288          2               10
129          7               20
115          1               6
542          2                8
255         10               6
206          5                7

Race
White
Nonwhite

3,892          5               11
390          5              18

Source: National Bladder Cancer Study. Hartge. P.. Hoover. FL. and Kantor. A. Bladder cancer risk and pipes.
cigars. and smokeless tobacco. Cancer. 55: 901-906. 1985. Research supported by the National Cancer Institute,
the Food and Drug Administration. and the Environmental Protection Agency.

Gritz, Ksir, and McCarthy surveyed a sample of 214 students at the
University of Wyoming (29). In their sample, 27.1 percent of males and
4.1 percent of females reported "current use," with the criterion for
"current use" unspecified. The vast majority of users (84 percent) used
moist snuff.

Glover and his colleagues reported a survey of 5,894 students in
physical education classes at 72 colleges and universities from 8 States
(Oregon, Arizona, Colorado, Oklahoma, Minnesota, Ohio, South Carc~
lina, and Connecticut) (30). `l%enty-two percent of the males who were
surveyed reported using smokeless tobacco compared to 2 percent of
the females. Combined rates of use for both sexes ranged from 15 per-
cent in Oklahoma to 8 percent in Connecticut. The majority of the users
reported using less than one can or pouch per week.

Adolescent Use

Studies of school-age youth conducted since 1980 are summarized in
table 12 13145). Five different criteria for classifying use have been
selected for data display: daily use, weekly use, monthly use, current
use (no frequency specified), and ever used.
Recent regional data on the use of smokeless tobacco have been col-
lected by a number of National Cancer Institute grantees in the course

17


TABLE EL-Prevalence of Use of Smokelese lbbacco Among Youth by
      Gender and Grade: Regional and StateLevel Surveys
      Reported since 1!Bo*

LOC.StiOll
keference~

Grade&$    Malea    Females Total       I

Daily Use
Arkansas (31)
Arkansas (32)
Nebraska (33)
Ohio (34)
Chewing Tobacco
Snuff
Oregon (35)

Oregon (36)

wisconsin (37)

lo-12
lo-12

7-12

4-12

7
9
10

7
a
9
10

7
8
9
10
11
12
lbtal

26.0
-

2.5

11.4
19.7

a.8
18.5
23.1
4.6
5.8
9.7
10.6
3.0
6.0
3.0
8.0
11.0
15.0

-

-

-

0.0

0.2
0.4

0.7
0.0
2.4

-

-

-

-

0.0
0.0
0.0
0.0
0.0
0.0

-

-       179
15.0       901
-      2,612

-      1.004
-      1,004
-       443
-       249
-        130
-       710
-       139
-        432
-       255

-        -
-        -
-
-
-        -
-        -

weekly use
(Or more often)
Nebraska (33)
wisconsin (37)

7-12

7
8
9
10
11
12
lbtal

4.8      0.0        -      2.616
12.0       -        -
18.0       -        -        -
15.0       -        -        -
24.0       -        -        -
25.0       -        -
37.0       -        -        -
-       1.0        -     25,000

Monthly Use
(Or more often)
Arizona (38)
Midwestern
states (39)
Nebraska (33)

8-12      18.4       -        -      1,080

lo-12      33.0      0.0        -       323
7-12      7.1       0.0        -      2.616

Current Use
(Frequency not specified)
Arkansas (31)     lo-12
Arkansas (32)       10
               11
               12
             T&al

31.8      2.2        -       179
-        -       13.8       326
-        -       20.6       330
-        -      23.7       245
36.7       2.2        -       901

18


TABLEIl2.-Continued

LOtXtiOll
(reference)       Grade(s)    M&Ii    Females    Total       n

Current Use (Cont.)
Colorado (40)      lo-12      21.6      0.6        -      1,119
Colorado (4 1)      10-12      26.0       0.0        -        445
Louisiana (42)f
1976-1977
Chewing Tobacco    8-9       11.0       -        -        -
              lo-11      17.0       -        -        -
              12-13      25.0       -        -        -
               14-15      24.0       -        -        -
              16-17      15.0       -        -        -
Snuff           8-9       4.0       -        -        -
              10-l 1       7.0       -        -        -
              12-13      5.0       -        -        -
              14-15      11.0       -        -        -
              16-17       5.0       -        -        -
              Total       -        -        -      2.880
1981-1982
Chewing Tobacco   8-9       24.0       -        -        -
              IO-11      32.0       -        -        -
              12-13      39.0       -        -        -
              14-15      43.0       -        -        -
              16-17      15.0       -        -        -
             Total       -        -        -      1.981
Snuff          8-9       21.0       -        -        -
              lo-11      26.0       -        -        -
              12-13      32.0       -        -        -
              14-15      30.0       -        -        -
              16-17      14.0       -        -        -
             lbtal       -        -        -      1,981
Pennsylvania (43)    7-12      30.0      0.0        -       538
Texas (44)         7-12      19.0      0.0        -      5,392
Wyoming (29)      7-9       24.5       1.2        -      2,408

Ever Used
Arkansas (45)      K
Ohio (34)
Chewing Tobacco   4-12
             lbtal
Snuff           4-12
             Total

Oregon (35)         7
              9

              10
Wisconsin(37)       7
              8
              9
              10
              11
               12
            Total

58.0
-
64.0
-

63.4
72.7
76.7
32.0
45.0
47.0
50.0
47.0
48.0
-

12.0
-
24.0
-

19.9
16.4
23.8

-

-

21.4       112

-        -
-      1,007
-        -
-      1,007
-        445
-        249
-        133
-        -
-        -

-        -
11.0     25,000

o Unless otherwise indicated, figures represent the usa
been made for studies that provide for more than one c E...
                         of chewing tobacco andlor snuff. Multiple entries have
                                    
                             sslfrcatmn cntenon.

t Age listed rather than grade.

19


of their ongoing research on tobacco use by youth (4s). Through col-
laboration, these investigators have achieved more standardization in
data collection than in previous studies, which makes comparisons
among the different locales more meaningful. Although there were
some differences in methodology, all of the studies addressed one or
both of the following research questions:

1. What percentages of males and females have ever used smokeless
t&lCCO?

2. What percentages of males and females have used smokeless
  tobacco in the last 7 days?
Adolescent males may be subject to pressures that simultaneously
discourage and encourage smokeless tobacco use. Underreporting of
use may result from the presence of teachers and the setting in which
the survey is administered. Overreporting may result from peer
pressure to be seen as a smokeless tobacco user. Accurate reporting
may be facilitated by collecting breath or saliva samples when surveys
are completed. Respondents who believe that their se&reports can be
objectively verified via biochemical testing tend to provide more accu-
rate responses (47-49). Biochemical validation was used in 14 of the 17
subsamples reported in table 13.
Most studies do not distinguish between snuff and chewing tobacco.
In reports where the two have been separated, both substances were
found to be in use (344243).
Rates of smokeless tobacco use were consistently higher among
males than females. This difference is especially marked when more
precise classifications for regular use are employed. While substantial
numbers of adolescent females report having tried smokeless tobacco at
least once, very few use it on a regular basis (3335,37,39,&J.
The use of smokeless tobacco by youth was generally higher in rural
than urban areas, in small communities, and in areas where there is a
tradition of smokeless tobacco use (Z&$37,46). However, high rates of use
have also been reported in large metropolitan areas as well (37,40,46).
able 14 smmm&es data on smokeless tobacco use by ethnic groups
collected by investigators using standardized questions (46). lb date, lit-
tle information has been available on smokeless tobacco use by non-
whites, and some early research suggested that minority youth were
not taking up the practice (42). In these studies, however, Hispanic
youth showed rates of smokeless tobacco use comparable to whites, and
Native American rates were consistently higher. In most locales, use was
less common among Asians and blacks. Nationally, black college stu-
dents are less likely to use snuff than are white college students Itable 6).
Prevalence estimates for smokeless tobacco use by black adults,
however, have equaled or exceeded those of whites (tables 5 and 11).
The likelihood of using smokeless tobacco appears to increase with
age as well as over time (32-35,37,42,46). Only one study has collected

20


TABLE 13.-Prevalence of Use of Smokeless lbbacca Among Youth by
     Gender and Grade: Local Surveys Using
      stana Questions

Sample

           Males            Females

Grade   Percentage     n    Percentage     Il

Used in Last 7 Days
California
Suburban/Rural

Minnesota
Suburban/Urban
Montana
Urban

New York
Urban

New York
New York City
New York
Suburban

Oregon
Suburban/Rural

Oregon
Suburban/Urban

Southeastern
unitf!d states
10 SMSA's

Vermont
Rural

Vermont
Urban

Washington
Rural

Washington
RLUal

4.7      (469)      0.7      (407)
14.8      (574)      1.4      (557)
9.2      (487)      1.6      (499)

9       18.1     (2.015)      2.4     (2.146)

9.4      (477)      2.0      (4031
11.9      (429)      1.5      (392)
13.9      (446)      3.2      (402)

3.9      (306)
2.9      1272)
10.7      (252)

0.3
it:

ww
(275)
(243)

6        1.1     (1,488)      0.9     U.494)

7        3.0     (2,016)      0.0     (1,811)

6
ii
9
10
11

E
13:6
17.3
22.2
22.7

(602)
(627)
(6631
(572)
(514)
(440)

0.9
0.8
it:
2:3
0.5

(542)
(618)
608)
(567)
(471)
(431)

6
7
;

1.9      (571)      0.4      625)
4.6      (570)      1.4      (575)
6.8      (514)      0.8      (533)
14.8      (588)      1.2      (575)

6       9.8      (305)      1.3      ww
7       12.1      (346)      0.6      (325)
8       10.4      v79)      1.6      (313)

9.3      mw      0.3      (317)
14.9      (328)      1.0      (289)

4       2.8      (216)      0.0      w9)
5        4.8      (207)      1.0      cw
6       5.4     (204)      0.0      (193)

4   2:
6       8.8
7       13.1
8       14.8

(45)      0.0       (47)
(141)      1.3      056)
W8)      2.1      (964)
(521)      4.1      (514)
(316)      5.2      (325)

10       23.7      (215)      0.4      (233)

21


TABLE 13.-Continued

                         Males            Females
Sample          Grade   Percentage     P    Percentage     n

Ever Used
California
Suburban/Rural

California
pG/;pples
California

Los Angeles
SMART

California
Los Angeles
TVSP
Minnesota
Suburban/Urban
Montana
Urban

New York
Urban

New York
New York City
New York
Suburban

Oregon
Suburban/Rural

Oregon
Suburban/Urban

Southeastern
united states
10 SMSA's

Vermont
Rural

Vermont
Urban

Wzu$inl@n
Waterloo. Canada
Suburban/Rural

32.6
56.2
56.7

24.9

7.8
19.6
20.0

6.7

I:;:;
(504)

(310)

25.3      (479)
31.9      1429)

ii::

32.0     (1,240)      6.9

(480)
(418)

(1,474)

62.1     (2,001)     22.9     (2,133)

41.0
56.9
68.2

17.5
19.3
24.6

23.1      (307)      3.4
33.5      (272)      5.1
47.8      (255)      7.0

i275;
(24.3)

6.7     (1,488)      3.0     u,494

25.3     (2.016)      4.1     11,811)

48.3      (607)     16.2
57.9      639)     19.8
64.5      (677)     23.8
70.4      (577)     26.7
74.7      (5221     31.1
77.5      (445)     34.2

(551)
I:?;;
(576)
(4851
(436)

32.4      (568)
44.9      (568)
54.1      (51.2)
61.3      1589)

E
17:2
24.7

(528)
f%J
(575)

47.6
49.0
51.4

11.4      ew
13.5      (325)
15.6      (314)

38.8      1289)      8.2      (317)
54.8      (332)      7.2      (290)

17.4      (213)
26.2      (207)
39.8      (206)

%!I
3.1

l%1
(193)

15.6
27.0
49.0
52.0
58.9

145)
(141)
1E1
(316)

0.0       (47)
7.7      (156)
13.0      (964)
16.0      (514)
20.1      (325)

73.5      (215)

26.0      (281)

30.9


5.5

WW

(444)

22


TABLE 14.-Mean Frequency of Smokeless Tihacco Use
     During Last 7 Days by Ethnicity of Male Respondents

Sample

California
Suburban/Rural
Grades 6-8

Ethnkity

Asian
Black
Hispanic
White

   Prevalence

n         %


192        3.7
118         6.1
188        11.2
1,046        11.4

Minnesota          Asian                   36        13.9
Suburban/Urban     Black                  201         4.0
Murray         Hispanic                  24        45.8
               Native American            38        18.4
               White                1,602        19.6

New York           Asian                  119         2.5
New York City      Black                 205        0.5
Grade 6        Hispanic                510         1.0
               White                   501         1.2

New York          Asian                  23        4.3
Suburban         Black                    47         2.1
Grade 7         Hispanic                 39         2.6
               Native American            26         3.8
               White               1,796         3.3

Oregon            Asian                   38         5.3
Suburban/Rural     Black                   33        15.2
Grades 6-11      Hispanic                61        16.4
               Native American           120        23.3
               White               3.162        14.2

Oregon            Asian                   71         2.8
Suburban         Black                  231         3.9
Grades 6-9       Hispanic                 26        0.0
               Native American            48        12.5
               White               1,847         7.6

Southeastern
uIlited states
10 SMSA's

Black                 258        3.9
White                 652        14.0

Washington
Rural
Grades 4-8

Asian
Black
Hispanic
Native American
White

148         6.1
119         1.7
111         9.0
179        30.7
1,434         9.4

23


both cross-sectional and longitudinal data. Hunter and her colleagues
assessed tobacco use by children in Bogalusa, Louisiana, in 1976-77 and
again in 1981-82 (az). The use of both snuff and chewing tobacco in-
creased over time within age categories, within age cohorts, and across
age categories (table 12). A decrease in use was observed in the oldest
age category, 16-17 years old, but has not been seen in other locales
(tables 12 and 13). The decrease may reflect agerelated changes in nor-
mative behavior particular to that ares or a cohort effect.
Peer and family members are found consistently to be important in-
fluences on smokeless tobacco use by children and adolescents. Young
users of smokeless tobacco have more friends who also use smokeless
tobacco (343fQ9,&~ and may themselves identify friends' encourage
ment as a reason for use (35,,44). Users of smokeless tobacco are also
more likely to have family members who themselves use smokeless
tobacco (34,3&$5) and encounter less parental disapproval of the prac-
tice (31,359.
In a special National Program Inspection study prepared by the Of-
fice of the Inspector General of the Department of Health and Human
Services, young current and former users of smokeless tobacco were
interviewed in depth (So). `AVO hundred and ninety students in junior
and senior high schools from 16 States volunteered to participate. AU
had used smokeless tobacco on a weekly or daily basis. While this study
was not designed to provide prevalence estimates, it provides useful in-
formation about the attitudes and practices of some adolescent smoke
less tobacco users.

Over 90 percent of these respondents used snuff exclusively, and over
55 percent indicated that they would have strong cravings if they tried
to quit. On the average, this group reported first trying snuff at age 10
and beginning regular use by age 12. Fifty percent cited pressure from
friends as their primary reason for initiating use, but continued use was
most often attributed to enjoyment of taste (64 percent) and habit
strength ("being hooked," 37 percent). Over 85 percent thought that
dipping and chewing can be harmful to health, but less than 55 percent
considered regular use to present a moderate or severe risk.

CONCLUSIONS

1. Recent national data indicate that over 12 million persons used
some form of smokeless tobacco (chewing tobacco and snuff) in
1985 and that approximately 6 million used smokeless tobacco
weekly or more often. Use is increasing, particularly among
young males.

2. The highest rates of use are seen among teenage and young adult
males. A recent national survey indicates that 16 percent of
males between 12 and 25 years of age have used some form of

24


smokeless tobacco within the past year and that from onethird to
onehalf of these used smokeless tobacco at least once a week. Use
by females of all ages is consistently less than that of males;
about 2 percent have used smokeless tobacco in the last year.
3. State and local studies corroborate the national survey findings.
The prevalence of smokeless tobacco use by youth and young
adults varies widely by region, but use is not limited to a single
region. In several parts of the country, as many as 25 to 35 per-
cent of adolescent males have indicated current use of smokeless
tobacco.

RESEARCH NEEDS

More systematic and detailed national and local surveys on smoke
less tobacco should be conducted.* National probability sample
surveys need to be supplemented with surveys of suspected "hot
spots" to detect the extent of high-risk areas in the country and the
prevalence of use in these areas.

Standard&d methods are essential to facilitate appropriate compari-
sons among data. The current state of assessment is similar to the early
days of research on cigarette smoking before standardized formats for
assessment of prevalence and quantification of dosage became available.
Accurate and reproducible dosage measurement for smokeless tobacco
products is needed. Standardization may prove more difficult than for
cigarette smoking because of the multiplicity of product forms.
Specific items that require standardization include the following

o Collection of data separately for snuff and chewing tobacco.
o Definition of user classified according to the frequency of use. `Lb
date, little attention has been given to finer distinctions of use, in-
cluding quantity used, the appropriate unit of measurement, and
time that the product is allowed to remain in the mouth

o Description of use. Data need to be gathered on patterns of use as
well as the relationship of use to cigarette smoking.

o Reporting of age of initiation and duration of use.

o Definition of quit attempts and a quitter.
o Natural history of smokeless tobacco use and its relationship to
other substance use, including other forms of tobacco, particularly
cigarettes.

o Surveys of adequate sizes to permit stratification of the samples
by relevant variabies such as gender, age, ethnicity, socioeconomic
status, cigarette smoking status, and various behavioral factors
such as attitudes and knowledge, peer pressure, and academic
status.

* The 1986 OSH Adult Use of Tobacco Survey will address many of the items listed below.

25


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Smokeless tobacco: The folkIore and social history of snuffing, sneez-
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(2) Schuman, L.M. Patterns of smoking behavior. In: M.E. Jarvick, J.W.
Cullen, E.R. Critz, T.M. Vogt, and L.J. West teds.). Research on smok-
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(3) Shelton, A. Smokeless sales continue to climb. Tobacco Reports, p. 42.
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(4) Maxwell, J.C., Jr. Chewing, snuff is growth segment. Tobacco Reports,
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(5) Winn, D.M. Tobacco chewing and snuff dipping: An association with
human cancer. In: I.K. O'Neil, R.C. Borstel, C.T. Miller, J. Long, and H.
Bartsch (eds.). N-Nitroso Compounds Occurrence, Biological Effects
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(6) Rosenfeld, L., and Cahaway, J. Snuff dipper's cancer. Am. J. Surg. 106:
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(7) Agricultural Market Service. Tobacco in the United States. U.S.
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(9) Bantle, L.F. Smokeless tobacco-A trend to watch. Ihbak J. Int. 4:
344-346, 1980.

(10) Rizio, D. Smokeless tobacco. Thbak J. Int. 2: 183-184, 1984.
(ll/ U.S. Department of Agriculture, Economic Research Service. Tobacco:
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(12) U.S. Department of Agriculture, Agricultural Marketing Service.
  Annual report on tobacco statistics, 1973. (Statistical Bulletin No. 528).
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(13) U.S. Department of Agriculture, Agricultural Marketing Service.
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(14) U.S. Department of Agriculture, Agricultural Marketing Service.
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(15) U.S. Department of Agriculture, Agricultural Marketing Service.
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(16) U.S. Department of Agriculture, Agricultural Marketing Service.
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(17) U.S. Department of Agriculture, Agricultural Marketing Service.
Tobacco stocks, as of January 1, 1986. Washington, D.C., 1986.

26


(18) National Clearinghouse for Smoking and Health. Use of tobacco: Prac-
tices, attitudes, knowledge, and beliefs. U.S. Fail 1964 and Spring 1966,
  July 1967.

(19) U.S. Department of Health, Education, and Welfare. Smoking and
health-A report to the Surgeon General. Office on Smoking and
  Health (DHEW Publication No. PHS 79-50066). 1979.
(20) National Clearinghouse to3 Smoking and Health. Adult use of tobacco,
1975. U.S. Department of Health, Education, and Welfare, Public
  Health Service, 1976.

(21) National Center for Health Statistics. National Health Interview
  Survey, 1970 (unpublished).

(22) Simmons Market Research Bureau, Inc. Study of Media and Markets,
  1980-1985.

(23) Simmons Market Research Bureau, Inc. Simmons National College
  Study, 1983 and 1985.

(24) Office on Smoking and Health. Current Population Survey, 1985
  (unpublished).

(25) Rouse, B.A. National prevalence of smokeless tobacco use. Presented
at the NIH Consensus Development Conference on the Health ImpIica-
  tions of Smokeless Tobacco Use, Bethesda, Maryland, January 13-15,
  1986.

(26) U.S. Department of Commerce, Bureau of the Census. (CP Series P25,
  No. 922), 1982.

(27) Hartge, P., Hoover, R., and Kantor, A. Bladder cancer risk and pipes,
  cigars, and smokeless tobacco. Cancer 55: 901-906, 1985.
(2%) Glover. E.D., O'Brien, K., and Holbert, D. Prevalence of smokeless
  tobacco use in Pitt County, North Carolina. Int. J. Addict. (in press).
(29) Gritz, E.R., Ksir, C.. and McCarthy, W.J. Smokeless tobacco use in the
  United States: Past and future trends. Ann. Behav. Med. 7: 24-27,1985.
(30) Glover, E.D., Johnson, R., Laflin, M., and Christen, A. Smokeless
  tobacco trends in the United States. World Smoking and Health (in
  press).

(31) Marty, P.J., McDermott, R.J., Young, M., and Guyton, R. Prevalence
and psychosocial correlates of dipping and chewing in a group of mraI
  high school students. Health Educ. (in press).
(32) Marty, P.J., McDermott, R.J., and Wihiams, T. Patterns of smokeless
tobacco use in a population of high school students. Am. J. Public
  Health 76: 190-192,1986.
CW Newman, I.M.. and Duryea. E.J. Adolescent cigarette smoking and
  tobacco chewing in Nebraska. Nebr. Med. J. 66: 243-244, 1981.
(34) Bonaguro, J.A., Pugy, M., and Bonaguro, E.W. Multivariate analysis
of smokeless tobacco use by adolescents in grades four through twelve.
  Health Educ. (in press).

(35) Lichtenstein, E., Severson, H.H., Friedman, L.S., and Ary, D.V. Chew-
ing tobacco use by adolescents: Prevalence and relation to cigarette
  smoking. Addict. Behav. (in press).

27


(36) Severson, H., Lichtenstein, E., and Gallison. C. A pinch or a pouch in-
  stead of a puff? Implications of chewing tobacco for addictive pro-
  cesses. Bulletin of Psychologists in Addictive Behaviors 4: 85-92,1985.
137) Jones, R.B. Smokeless tobacco: A challenge for the 80's. Journal of the
  Wisconsin Dental Association 10: 71'7-721, 1985.
(38) Chassin. L., Presson, C.C., and Sherman, S.J. Stepping backward in
  order to step forward: An acquisition oriented approach to primary
prevention. J. Consult. Clin. PsychoL (in press).
(39) Chassin, L., Presson. C.C., Sherman, S.J., McLaughlin, L., and Gioia,
  D. Psychological correlates of adolescent smokeless tobacco use.
  Addict. Behav. (in press).

(40) Greer, R.O., and Poulson, T.C. Oral tissue alterations associated with
the use of smokeless tobacco by teenagers, I. Clinical findings. Oral
  Surg. 56: 275-284, 1983.

(41) Paulson, T.C., Lindenmuth, J.E., and Greer, R.O. A comparison of the
use of smokeless tobacco in rural and urban teenagers. CA 34: 248-261,
  1984.

(42) Hunter, S.M., Croft, J.B., Burke, G.L., Parker, F.C., Webber, L.S., and
Berenson, G.S. Longitudinal patterns of cigarette smoking and smoke
  less tobacco use in youth. Am. J. Public Health 76: 193-195,1986.
(43) Guggenheirner, J., Zullo, T.G., Krupee, D.C., and Verbin, R.S. Chang-
ing trends of tobacco use in a teenage population in western Pennsyl-
  vania. Am J. Public Health 76: 196-197, 1986.
(44) Schaefer, S.D., Henderson, A.H., Glover, E.D., and Christen, A.G. Pat-
  terns of use and incidence of smokeless tobacco consumption in school-
age children. Arch. Otolaryngol. (in press).
(4.5) Young, M., and Williamson, D. Correlates of use and expected use of
smokeless tobacco among kindergarten children. Psychol. Rep. 56:
  63-66,1985.

(46) Boyd, G.M.. et al. Use of smokeless tobacco among children and
  adolescents in the United States. Prev. Med. (in press).
(47) Evans, R.I., Hansen, W.G., and Mittehnark. M.B. Increasing the valid-
ity of self-reports of smoking behavior in children. J. Appl. Psychol. 62:
  521-523. 1977.

(48J Murray, D.M.. O'Connell, C.M., Schmiel. L.A., and Perry, C.P. The
  validity of smoking self-reports by adolescents: A reexamination of the
  logic and pipeline procedure. Addict. Behav. (in press).
(49) Bauman, K.E., and Dent, C.W. Influence of an objective measure on
self-reports of behavior. J. Appl. Psychol. 67: 623-638, 1982.
(50) Office of the Inspector General. Youth use of smokeless tobacco: More
than a pinch of trouble. U.S. Department of Health and Human Ser-
  vices, January 1986.

28


Chapter 2.

CARCINOGENESIS ASSOCIATED WTTH
  SMOKELESS TOBACCO USE


CONTENTS

Introduction.. ................................... ..3 3

Epidemiologic Studies and Case Reports of Oral
CancerinReIationtoSmokelessTbbaccoUse ............. .33
DataFromNorthAmericaandEurope  .............. .33
  DataFromAsia  ................................ .42
summary......................................4 4
  References ................................... ..4 4

Epidemiologic Studies of Other Cancers
inRelationtoSmokeless'I%accoUse ................... .47
  NasalCancer.................................... 8
EsophagealCancer............................... 8
LaryngealCancer................................ 0
  StomachCancer ............................... ..5 1
Urinary'It-actCancer  ............................ .52
  Other Cancers .................................. .54
  summary.. .................................. ..5 5
  References ................................... ..5 6

Chemical Constituents, Including Carcinogens,
of Smokeless Tobacco  ............................... .58
Chemical Composition of Smokeless Tobacco .......... .58
Carcinogens in Smokeless `Ibbacco .................. .58
Summary......................................6 5
  References ................................... ..6 7

Metabolism of Constituents of Smokeless Tobacco .... .70
  Metabolism of NNK ........................ .71
  Metabolism of NNN ........................ .73
  Metabolism of NMOR  ...................... .74
  summary ................................ .75
  References  ............................... .75

Experimental Studies Involving Exposing Laboratory
Animals to Smokeless `Ibbacco or Its Constituents ......... .79
Bioassays With Chewing Tobacco  .................. .79
Bioassays With Snuff. ........................... .83
Bioassays With Constituents of Smokeless Tobacco  .... .86
Mutagenicity Assays and Other Shoti'Ihrrn lb&s ...... .88
Summary.. .................................. ..8 9
  References ................................... ..8 9

cOnclusions........................................92

ResearchNeeds.....................................93

31


This chapter presents the results of a systematic review of the world's
medical literature describing experimental and human evidence perti-
nent to the evaluation of smokeless tobacco as a potential cause of
cancer. Five categories of research relevant to assessing the role of
smokeless tobacco in cancer causation were defined:

1. Epidemiologic studies and case reports of oral cancer in relation
to smokeless tobacco use.

2. Epidemiologic studies of other cancers in relation to smokeless
toba~0 use.

3. Chemical constituents of smokeless tobacco.

4. Metabolism of constituents of smokeless tobacco.

5. Experimental studies involving exposing laboratory animals to
smokeless tobacco or its constituents.

consensus summari es of the literature in each of these categories
were prepared and form the basis of this report. In addition, recommen-
dations for future i-search to clarify suggestive findings or fi.lI gaps in
knowledge are made.

EPIDEMIOLOGIC STUDIES AND CASE REPORTS
OF ORAL CANCER IN RELATION TO
SMOKELESS TOBACCO USE

Because smokeless tobacco products used in different regions of the
world vary considerably in composition and usage patterns, this section
will consider North American and European data separately from
Asian data. Citations to the literature from India and other Asian coun-
tries where quids containing tobacco and other ingredients are com-
monly used orally focus on articles that attempt to distinguish tobacco
from other ingredients in the quids as possible determinants of cancer
risk.

Data From North America and Europe

Although about a dozen informative epidemiologic studies of smoke
less tobacco use and oral cancer in North America or Europe have been
reported, only a few were specifically designed to examine this relation.
There are two major reasons for the relative paucity of studies. Apart
from the recent increased prevalence in use of smokeless tobacco, the
habit has not been widely practiced in America during this century, ex-
cept in localized areas such as parts of the rural South (1,2). Further-
more, cancer of the mouth is uncommon in the Western Hemisphere,

33


exacerbating the difficulty of conducting epidemiologic investigations,
particularly cohort studies, into the relation between smokeless tobacco
and oral cancer. The ageadjusted incidence rate for cancers of the buc-
cal cavity and pharynx in the United States is approximately 11 cases
per 100,000 population per year, with these tumors accounting for
about 3 percent of all cancer deaths (3). Nevertheless, sufficient informa-
tion is available to evaluate whether the use of smokeless tobacco
increases the risk of oral cancer.

case studies

In their review of 566 oral cancer patients treated in two hospitals in
Nashville, Rosenfeld and Callaway (4,5) noted that the proportion of
women (61 percent) with buccal and gingival carcinoma was higher than
the proportion of men (36 percent). Approximately 90 percent of women
with buccal and gingival carcinoma used snuff for 30 to 60 years; in con-
trast, 22 percent of women with cancers in other oral cavity subsites
used snuff. Many of these women began practicing "snuff dipping,"
namely, the placement of tobacco snuff in the gingivobuccal sulcus, be
tween the ages of 10 to 20 years. These reports are typical of numerous
and sometimes large series of cases from the South, which reported that
high percentages of patients with gingivobuccal cancers were snuff dip-
pers or tobacco chewers (613). The articles describing these case series
generally did not use comparison (control) groups, but the authors con-
sistently commented on an apparently high prevalence of the use of
snuff by the cancer patients. Clinicians also noted that the usual male
predominance for epidermoid carcinomas of the oral cavity diminished
or disappeared for the subgroup of gingivobuccal carcinomas occurr@
in geographic areas where there was relatively common use of snuff and
chewing tobacco.

Ahblom reported in the 1930's on a possible association between
smokeless tobacco and cancer in Sweden (14). Among male patients
with cancers of various sites seen at the Ftadiumhemmet (Stockholm),
the use of snuff or chewing tobacco was reported in 70 percent with buc-
cal, gingival, and "mandibuIar" cancers as compared to 26 to 37 percent
with cancers in other oral subsites, the larynx, pharynx, and esophagus.
Ax611 et al. reviewed medical records of male patients with squamous
cell carcinoma in the oral cavity diagnosed between 1962 and 1971 and
recorded in the Register of the Swedish Board of Health and Welfare (Is).
The authors were only able to determine a history for the pattern of use
of snuff in 25 percent of eligible patients but commented that two
thirds of patients who were verified snuff users had oral cancers in
regions where the snuff was generally placed. Reports of a single or a
few cases, usually among male tobacco chewers, in the Northern United
States and Canada also described buccal carcinomas that were often
located precisely in the area where the tobacco was retained in the
mouth (1619)

34


In the early 1940's, Friedell and Rosenthal associated the use of snuff
or chewing tobacco with an exophytic, verrucous type of squamous car-
cinoma of the oral cavity (16). Ackerman described in detail the morpho
logic and clinical features of verrucous carcinoma of the oral cavity (20).
Where the lesions originated in the buccal mucosa, a history of chronic
use of chewing tobacco was elicited in 60 percent of the patients. The
morphologic description was that of a well-differentiated, locally inva-
sive, papillary squamous carcinoma, often in association with leuko
plakia. In more than half of these patients, there was poor oral hygiene
and carious and missing teeth.

In summary, clinical and pathological reports published during the
past four decades in the United States and elsewhere have commented on
the use of smokeless tobacco by oral cancer patients and have described
the entity known as snuffdipper's carcinoma (4,7,11), providing the basis
for the hypothesis that the prolonged use of snuff or chewing tobacco is
associated with an increased risk of low-grade, verrucal or squamous cell
carcinoma of the buccal mucosa and gingivobuccal s&us.

case control studies

Most of the epidemiologic evidence comes from several case-control
studies of oral cancer. The low prevalence of smokeless tobacco use in
most North American populations contributes to a low statistical effi-
ciency in most of these studies. Good information has been obtained,
however, from studies that were either very large, conducted in an area
of high prevalence of smokeless tobacco use, or analyzed according to
site within the oral cavity (since the tissue affected by snuff use appears
to be highly localized). One study, by Winn et al., with these characteris-
tics consequently provides the most informative body of data on the
carcinogenicity of smokeless tobacco in North America (21).

The major concern for validity in the epidemiologic studies of smoke
less tobacco and oral cancer is uncontrolled confounding. A smalI num-
ber of subjects in crucial categories prevented efficient adjustment for
confounding by stratification in many of these studies. Many of the
studies were conducted before the advent of sophisticated epidemic
logic analyses and make no attempt to control confounding. The two
primary confounding factors of concern are alcohol consumption and
smoking (22). Alcohol consumption is a strong risk factor for oral can-
cer. It is not clear on a priori grounds, however, to what extent alcohol
consumption would be correlated with smokeless tobacco use. The rela-
tion between smoking, also a strong risk factor for oral cancer (2), and
smokeless tobacco use may be complex. Users of smokeless tobacco
may be more likely to have been smokers at some time. On the other
hand, heavy users of smokeless tobacco typically cannot be heavy users
of cigarettes, so that smoking is p resumably negatively correlated with
smokeless tobacco use. Failure to control confounding by smoking would
therefore lead to underestimates of the effect of smokeless tobacco.

35


TABLE l.-Smokeless Tobacco and Mouth Cancer,
      Case-Control Data From Moore et al. (23,24)

Smokeless Tobacco      Mouth Cancer Cases

controls

Users                     26                12

Nonusers                    14                26
Totals                      40                38
Crude RR = 4.0      95%.Confidence Interval:       1.6-10

Chronologically, the first casecontrol study of smokeless tobacco
was conducted by Moore et al. in Minnesota (23,24). Patients at the
University of Minnesota `lhrnor Clinic with a diagnosis of cancer of the
mouth were interviewed about tobacco use as part of a general inter-
view procedure for clinic patients. Surgical outpatients who received
the same interviews served as controls. Prom the data that were
reported by these authors, one can calculate a crude relative risk
estimate for mouth cancer among smokeless tobacco users of 4.0 with a
95percent confidence interval of 1.6-10 (table 1). An oddity was an ap-
parent lack of effect for other forms of tobacco use. A partial explana-
tion might be negative confounding between smokeless and smoked
tobacco; indeed, 26 of the 40 cases of mouth cancer chewed tobacco.
Still, the extent of disparity in crude effect estimates for smokeless
tobacco (relative risk estimate 4.0) and smoked tobacco (all relative risk
estimates < 1.0) is surprising.

Wynder et al. reported on a case-control study of squamous cell
cancers of the upper alimentary and respiratory tract that was con-
ducted at Sweden's Radiumhemmet in 1952-55, including 33 tongue
cancer patients, 14 lip cancer patients, 19 gingival cancer patients, and
8 patients with cancer of the buccal mucosa, among others (25). Con-
trols were patients with cancers of the skin, head, and neck other than
squamous cell carcinoma, stomach cancer, lymphoma, salivary-gland
tumors, leukemia, sarcoma, cancers of the colon and rectum, and
cancers of the female genital tract. A variety of risk factors was exam-
ined, including the use of chewing tobacco. The authors state that the
data suggested that an increased risk is associated with the duration of
chewing tobacco for cancers of the gingiva and oral cavity but not for
cancers of the tongue, lip, hypopharynx, esophagus, or larynx, but the
data as presented do not permit an estimation of risk. In addition, data
were not adjusted for other potential confounders, including cigarette
smoking. Wynder and colleagues also reported in 1957 data from a
similar hospital-based casecontrol study of mouth cancer conducted in
New York (26). ?bbacco chewing was found to be more common among
men with oral cavity cancers than among controls; but it was noted that
almost all of these patients also drank alcoholic beverages and smoked
and no further analyses were attempted.

36


TABLE 2.-Smokeless Tobacco and Mouth Cancer,
     CaseControl Data From Peacock et al. (27)

Age

Smokeless
Tobacco


User

Nonuser

Total

  40-49         59-59          60-69


case controls     case controls     Case Controls


0 16       7 13      18 20

5 14       6 16       9 37

5 60      13 29      27 57

RR=0        RR = 1.4       RR = 3.7

RRMH = 2.0     95%.Confidence Interval: 1.0-4.2

Peacock et al. studied 56 cases of mouth cancer, including malignan-
cies of the buccal mucosa, alveolar ridge, and floor of the mouth, and
compared their tobacco histories with those of two control groups: 146
hospitalized controls with diagnoses other than cancer and 217 outpa-
tients (27). Agespecific results using the hospitalized controls are sum-
marized in table 2. The overall relative risk was estimated to be 2.0
(95percent confidence interval 1.0-4.2); the relative risk seemed to in-
crease with age with an estimate of 3.7 for the 60 to 69 age group. The
data were not reported in sufficient detail to control for confounding by
smoking, which presumably led to underestimates of the relative risk.
There was also insufficient detail reported to evaluate the relation be
tween the risk of mouth cancer and the amount or duration of smokeless
tobacco use.

In Atlanta, patients with oral, pharynx, and larynx cancer were com-
pared to three control groups having other mouth diseases, other can-
cers, or no cancer (28. Among urban women, 40 percent of the cases
used snuff compared to 3 percent or less of the controls (table 3). Among
rural women, 75 percent dipped snuff compared to 20 percent or less
among controls. Cigarette smoking was common in urban women and
not specifically controlled for. Few rural female cases smoked cigarettes
(7 percent) so confounding by smoking was minimal. The association
between snuff dipping and oral, pharynx, and larynx cancer in women
was generally evident in most age groups. Among the cases, the propor-
tion of snuff dippers was highest among oral cancer patients: 53/72 were
dippers compared to 2/18 pharynx and larynx cancer patients. Among
men, insufficient information was provided to obtain precise epidemic
logic estimates of the effect of chewing tobacco, although date from one
of the bar charts presented indicate that urban cases were more likely to
be users of smokeless tobacco than controls, that rural men with oral,
pharynx, and larynx cancer or mouth disease were more likely to chew
than controls, and that oral cancer patientu were more likely to chew

37


TABLE 3.-Estimated Relative Risks Associated With Snuff Use for
    Cancers of the Oral Cavity, Pharynx, and Larynx,
    Case.C!ontrol Data From Vogler et aL (2B), Females Only

oral/       Other
PlLSryIlXl      Mouth
Larynx      Disease

Other        No
ClUlCer      Cancer

Urban

User

Nonuser

Crude Relative
  Risk Estimate

RlUal

User

Nonuser
Crude Relative
  Risk Estimate

15           1           5           4

23          56         165         373


60.8         1.7         2.8         1.0*

41           4          26          17

14          33         103         133


22.9         0.9         2.0         1.0*

TABLE 4.-Smokeless Tobacco and Head and Neck Cancer by
     Anatomic Site, CaseControl Data From
     Vincent and Marchetta (29), Males Only

Smokeless
Tobacco Use


User

Nonuser

Total

Relative Risk
Estimate

95%~Confidence
Interval

Control Larynx


  5        2

  95       21

100       23


         1.8


       0.3-9.8

        oral    All Head
Phw   Cavity   and Neck


  3        9        14

30       24       75

33       33       89


1.9       7.1       3.5


0.4-8.3    2.4-21    1.3-9.8

than the pharynx and larynx cancer cases. Among men, confounding by
smoking could not be ruled out.

Vincent and Marchetta reported the results of a case-control study of
head and neck cancer according to anatomic site. Table 4 summarizes
the findings for males (29). The oral cavity seems to be the anatomic site
where the bulk of the effect is noted; only mild increases in risk were
estimated for the larynx and pharynx, whereas users of smokeless
tobacco were estimated to have a sevenfold greater risk for cancer of the
oral cavity. These estimates are imprecise because of the small number
of subjects and are uncontrolled for age and smoking.

38


TABLE 5.-Estimated Relative Risk for Cancer of the Head and Neck
     From Smokeless `lbbacco Use by Anatomic Site,
     Third National Cancer Survey (311, Males Only

Relative Risk Estimate

Anatomic Site         Low Exposure

High Exposure

Gum-Mouth                 5.6               3.9
Pharynx                   0.6                 -

Lip-Tongue                 0.3               1.1
LarYm                    2.0               1.7

Martinez reported on a case-control study in Puerto Rico of risk fac-
tors for cancers of the mouth, pharynx, and esophagus (XI). This
population-based study included 400 cases of epidermoid carcinomas of
those sites and 1,200 controls matched on age ( + 5 years) and sex to the
cases. One control per case was drawn from the same hospital or clinic
and two from the same community. There were 153 cases of mouth
cancer (115 male and 38 female) and 68 cases of pharyngeal cancer (55
male and 13 female). The authors concluded that "Patients with cancer
of the mouth did not often use chewing tobacco disproportionately. "
However, calculation of the relative risks of mouth cancer that are asso
ciated with chewing tobacco based on comparing the use of chewing
tobacco only with no tobacco use suggests a strong effect for oral and
pharyngeal cancer in males (data from table 13 in the paper). The esti-
mated relative risks were 11.9 (95percent confidence interval 2.5-56.4)
for oral cancer and 8.7 (95percent confidence interval 1.4-54.5) for
pharyngeal cancer among chewers. These numbers do not include the
experience of the many study subjects whose use of tobacco was
mixed" (that is, those who used any combination of cigarette, cigar,
and pipe smoking and chewing tobacco), and these calculations were
based on unmatched data.

Further evidence for the site specificity arose from a case-control
analysis of multiple cancers using data from the Third National Cancer
Survey (31). There were few female users of smokeless tobacco and
scanty data by site within the head and neck region even for males; the
findings do seem to indicate that the effect is greater for the site that is
labeled gum-mouth as opposed to other head and neck sites (table 5).

Browne et al. conducted interviews with 75 oral cancer patients, or
(usually) their next of kin, and 150 living sex-, neighborhood-, and
occupation-matched controls in the West Midlands area of the United
Kingdom where oral cancer mortality rates were high and tobacco
chewing was common among miners (32). Controls on average were
born about 10 years earlier than the cases. The proportion of tobacco
chewers was approximately the same among the 16 cases and 43 con-

39


trols who were miners, although data on this variable were missing for
onefourth of the cases, and the authors apparently assumed that all
cases with missing information were nonchewers. If the proportion of
tobacco chewers among the cases with missing information was similar
to those miners with known information, then the data would have
shown a positive association between chewing tobacco and oral cancer.
All of the miners with oral cancer who chewed tobacco also smoked
pipes, further complicating interpretation of this study.

Additional evidence that a carcinogenic effect of smokeless tobacco
may be greatest at the anatomic site of exposure came from Westbrook
et al. who compared the medical records of 55 female patients with
cancers of the alveolar ridge or buccal mucosa who were treated at the
University of Arkansas with those of 55 randomly selected female
hospital controls (33). Fifty of the cases, but only one control, were snuff
dippers, with the tumors among the cases typically appearing at the site
where the snuff was usually placed. No reliable estimates of risk can be
derived from this study because of the strong possibility that them was
not comparable elicitation of exposum information for cases and controls.
`Iwo large case-control studies were not reported in a way that enables

a meaningful quantitative assessment of the effect of smokeless to.
bacco in chewers and dippers compared to tobacco abstainers (34,35).
The first study found that 10 percent, and the second 9 percent, of male
oral cancer cases had ever chewed tobacco, while the corresponding fig-
ure for controls was 9 percent. These studies, like many of the others
cited here, were not undertaken specifically to evaluate the carcino
genicity of smokeless tobacco. Although the data seem to indicate a
weak relation, if any, between smokeless tobacco and cancer of the oral
cavity, the findings are uncontrolled for age, race, geography, and
smoking.
The recent casecontrol study of Winn et al. is by far the most infor-
mative study on the carcinogenicity of smokeless tobacco (21). The case
series comprised 255 women with oral and pharyngeal cancer who were
living in 67 counties in a high-risk (for oral cancer) region of North
Carolina. ?tyo female controls were obtained for all but a few cases and
were individually matched for age, race, source of ascertainment
(hospital or death certificate), and county of residence. There was a four-
fold increased risk of oral-pharyngeal cancer among nonsmoking white
women who dipped snuff. The association could not be explained by
smoking or alcoholic beverage consumption (21), denture wearing or
poor dentition (36), diet (37), or mouthwash use (38). The data provided
evidence for a strong relation between the duration of snuff use and risk
for cancer, as well as a striking localization of the carcinogen&y to the
gum and buccal mucosa (table 6). For long-term chronic users of snuff,
there was nearly a fiftyfold increase in risk for cancers of the gum and
buccal mucosa. Indeed, almost all of the patients with cheek and gum
cancers had dipped snuff.

40


TABLE 6.--Estimated Relative R&k of tipharyngeal Cancer
     According to Duration of Snuff Use and
     Anatomic Site, Winn et al. (21)

Anatomic          Duration of
Site           Snuff use (yrb

Relative Risk
Estimate

95%.
Confidence
IUtelVal

Gum and Buccal
Mucosa




Other Mouth
and Pharynx

  0
1 - 24
25 - 49
  1 50


  0
1 - 24
25 - 49
  2 50

1.0             -
13.8         1.9 -  98
12.6          2.7 -  53
48.0          9.1 - 250


1.0             -
1.7          0.4 - 7.2
3.8          1.5 - 9.6
1.3          0.5 - 3.2

Although some of the exposure information came from interviews
with next of kin, when the analysis was restricted to interviews with
study subjects, the association between snuff and oral cancer was even
stronger @9). Matched conditional logistic analysis yielded similar
results (35). Based on calculations of attributable risk, the authors
estimated that 87 percent of these cancers were due to the patients'
snuff-dipping habits. The authors also provided data that
demonstrated the negative confounding by tobacco smoking in the
population, raising the possibility of a serious validity problem with the
other studies that did not control for smoking. If the negative correla-
tion between the use of smokeless and smoked tobacco holds in other
populations, estimates of the carcinogenic effect of smokeless tobacco
in studies without the control of smoking may be underestimates. The
quantitative information that was provided by the Winn et al. study led
its authors to conclude that the long-standing use of smokeless tobacco
by Southern women was the principal cause of the elevated mortality
from oral cancer among women in the Southern United States.

Cohort Studies

Few cohort studies of smokeless tobacco have been undertaken
because of the rarity of both the exposure (smokeless tobacco use) and
the outcome (oral cancer) of most interest. Bjelke and Schuman (40)
reported on cancer mortality in cohorts of 12,945 Norwegian men and
16,930 American men and found increases in the risk of death for can-
cers of the buccal cavity, pharynx, and esophagus (relative risk
estimates ranged from 2.6 to 3.1(41); no further detail was given). They
noted a negative association between smoking and chewing tobacco,
confirming the pattern that was observed from the case-control
research. In a 16.year followup of U.S. veterans, Winn et al. reported no
deaths from oral or pharyngeal cancer among 951 smokeless tobacco

41


users who did not use other forms of tobacco (about 0.5 deaths were ex-
pected) but a significant increase in both oral and pharyngeal cancers
among smokeless tobacco users who were light smokers (42) These
data, as well as those from Bjelke and Schuman (40). were reported only
as abstracts in scientific journals or proceedings, with little or no detail
as to the methods used, hindering interpretation of the results.

Smith and colleagues followed a group of about 1,500 patients with
changes in the oral mucosa to evaluate the effects of smokeless tobacco
use (43,44). No oral cavity cancers were found in about 16,000 person-
years of followup. Based on the results of other studies, two or three
should have been detected over the study period. Smith gave little docu-
mentation of the methods that were employed for followup; however, 12
percent of the original group (201 subjects) were lost without any data
on outcome, and there was apparently no effort to trace them. It seems
likely that persons who died and persons who developed cancer, includ-
ing some with tumors of the oral cavity, may have been lost to followup.
In fact, no deaths among cohort members were reported, whereas
perhaps as many as 100 or more would have been expected among such
a cohort of middleaged adults, making Smith's data uninterpretable.

Data From Asia

The highest rate-e of oral cancer among the more than 100 that are
listed from population-based registries around the world that report stan-
dadized cancer incidence statistics are found in India (45). In many areas
of Asia, hospital statistics suggest that oral cancer is extremely common
and often accounts for 25 or more percent of all cancers (4649), propor-
tions that are far greater than in most areas of the United States where
oral cancers typically comprise only 3 percent of all malignancies (3). It
has long been thought that the chewing of quids that contain tobacco
and other substances is the cause of the increased risk of oral cancer in
these areas (50).

The smokeless tobacco products that are commonly used include to
bacco with betel leaf, areca nut, and lime mixtures (often referred to as
"pan"); Khaini (powdered tobacco and slaked lime paste); mishri (pow-
dered partially burnt black tobacco); nass (tobacco, ash, and cotton or
sesame oil; lime is used in Iran and certain Soviet Republics); and various
preparations that vary locally throughout the Southeast Asia region.

The inclusion of lime, areca nut, and other ingredients in many of the
smokeless tobacco-containing quids hinders the evaluation of the con-
tribution of tobacco per se to the increased risk of oral tumors. From
five investigations, however, relative risks of oral cancer among
chewers of betel quids with versus without tobacco can be calculated.
Data from these case-control studies, which were conducted in Cal-
cutta, Madras, Karachi, Bombay, and several parts of India and Sri
Lanka (4',51+%), reveal considerably higher risks of oral cancer for the

42


TABLE 7.-Relative Risk of Oral Canax From
     Betel Quid With and Without `Ibbacco
     (With 95Percent Confidence Limit)

Study
Location
(References)

Betel    Betel
Quid .      No
With  W%zut Chewing
Tobacco   Tobacco   Habit Remarks

Calcutta,
India (5054)

Madras,
India (5154)

Karachi.
Pakistan
(5&w

Bombay,
India (53)

India and
SI-iLanka
(47)

Cases         138       46
Controls        61      70
Relative risk     4.3      1.2
estimates   (3.0-6.1)  10.8-1.9)

Cases         219       33
Controls        35      144
Relative risk     25     0.91
estimates   115-41)   10.4-1.6)

135
256

25
99

Smokers not included
in these data. Only
buccal mucosa can-
cers considered.

Smokers not included
in these data. Only
buccaI mucosa and
tongue cancer cases
included. Numbers
reconstructed from
percentages and
totals.

Cases
Controls
ReIative risk
estimates

Cases
Controls
Relative risk
wtimates

cases
Controls
Relative risk
estimates

339
474
(11~~7,

238
513

120
  63
(7.Ot532,

  40
216
3.6
(2.4-5.2)

  44
152
3.0
(2.1-4.3)

  3
  8
2.9
(0.6-14)

88  Smokers not included
1.690  in these data.

129
1.340

6
47

Separate analyses
indicate that ele
vated risks of oral
cancer associated
with tobacco chew-
ing are found among
nonsmokers as well
as smokers.

Smokers not included
in these data. Only
buccaI mucosa
cancer considered.

use of tobacco-containing compared to nontobacco-containing quids
(table 7). The findings thus suggest that the addition of tobacco con-
tributes substantially to the elevated cancer risk among chewers,
although other differences between those who use versus those who do
not use tobacco-containing quids could influence the differences. Smok-
ing, however, is not such a difference, since most of the investigations
referred to in table 7 demonstrated high relative risks of oral cancer
(with excesses among tobacco chewers often exceeding tenfold com-
pared to nonquid users) among chewers who did not smoke, ruling out
confounding by cigarette smoking. The studies also generally found
that the large majority of oral cancer patients had been tobacco chewers
and suggest that the habit of quid chewing accounts for most of the oral
cancers in the diverse populations studied (5.5%).

43


Summary

Numerous case reports, especially in the South, have described oral
cancers among smokeless tobacco users. The tumors often arose at ana-
tomic locations where the tobacco was routinely placed. The number of
epidemiologic investigations evaluating the relation between smokeless
tobacco and oral cancer is not large, and several studies have method-
ologic limitations. The pattern of increased oral cancer risk among
smokeless tobacco users, however, is generally consistent across
studies, with evidence of an increasing risk with increasing duration of
exposure, and with excess risks tending to be greatest for those ana-
tomic sites where tobacco exposures are greatest. The best designed
study was drawn from a female population in the Southern United
States where exposure rates are high and potentially confounding vari-
ables could be taken into account. This study showed that chronic snuff
users were at substantially increased risk of oral cancers and that
nearly all tumors of the cheek and gum were due to snuff use. Evidence
from parts of Asia, where the prevalence of smokeless tobacco use is
high and oral cancer is the most common tumor, indicates a strong asso
ciation between the chewing of quids and oral cancer. Users of quids
that contain tobacco have much higher oral cancer rates than users of
quids that do not, and the association is not confounded by cigarette
smoking, raising the possib&ty that tobacco per se contributes to the
elevated oral cancer risk in this part of the world. In summary, users of
smokeless tobacco face a strongly increased risk of oral cancer, particu-
larly for the tissues that come in contact with the tobacco.

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1431 Smith, J.F., Mincer, H.A., Hopkins, K.P., and Bell, J. Snuff-dippers
lesion: A cytologicaI and pathological study in a large population. Arch
GtohuyngoI 92: 450-456, 1970.

1441 Smith, J.F. Snuff dippers lesion, a ten-year follow-up. Arch. OtoIaryn-
  gol.l01:2767-277, 1975.

46


(45) Waterhouse, J., Muir, C., Shanmugamnam, K., and Powell, J. Cancer
incidence in five continents, Vol. IV. Lyon, France, International
Agency for Research on Cancer, 1982.
(46) Pindborg, J.J. Epidemiologic studies of oral cancer. Int. Dent. J. 27:
  172-178, 1977.

(47) Wahi, P.N. The epidemiology of oral and oropharyngeal cancer. Bull.
  WHO 38: 495-521.1968.

(48) Hirayama, T. An epidemiologic study of oral and pharyngeal cancer in
  Central and Southeast Asia. BulL WHO 34: 41-69, 1966.
(49) Paymaster, J.C. Cancer and its distribution in India. Cancer 17: 1026,
  1964.

(So) Orr, I.M. Oral cancer in betel nut chewers in Travancore. Lancet 2:
  575-580, 1933.

(51) Chandra, A. Different habits and this relation with cheek cancer. Bull.
Cancer Hosp. Natl. Cancer Res. Center 1: 33, 1962.
(52) Shanta, V., and Krishnamurthi, S. A study of aetiological factors in oral
squamous cell carcinoma. Br. J. Cancer 13: 381, 1959.
(537 Jafary, N.A., and Zaidi, S.H. Carcinoma of the oral cavity in Karachi,
Pakistan: An appraisal. Trap. Doct. 6: 63, 1976.
(54) Jus~awdh, D.J.. and Deshpande, V.A. Evaluation of cancer risk in
tobacco chewers and smokers: An epidemiologic assessment. Cancer
  28: 244-252, 1971.

(55) Gupta, P.C., Pindborg, J.J., and Mehta, F.S. Comparison of carcine
genicity of betel quid with and without tobacco. An epidemiological
  review. EcoL Dis. 1: 213-219, 1982.
(56) Jayant. K.. Balakrishnan, V.. S anghvi, L.D., and Jussawalla, D.J.
Quantification of the role of smoking and chewing tobacco in oral,
pharyngeal, and esophageal cancers. Br. J. Cancer 35: 232-235, 1977.

EPIDEMIOLOGIC STUDIES OF OTHER CANCERS
IN RELATION TO SMOKELESS TOBACCO USE

The epidemiologic studies reported in the preceding section that
show an association between the use of smokeless tobacco and oral
cancers, particularly malignancies of the cheek and gum, indicate that
the topical exposure of tissues to tobacco can cause cancers at the site of
the exposure. In the United States, the tissues in direct prolonged con-
tact with the tobacco are generally those of the oral cavity. Smokeless
tobacco may occasionally come in contact with other tissues. One case
has been reported of squamous cell carcinoma that developed in the ear
of an individual in Minnesota who habitually placed snuff in his ear for
42 years at the site where the neoplasm developed (II. Although but a
single report, this highly unusual observation raises the possibility of a
carcinogenic potential of smokeless tobacco at other anatomic sites
when exposure is direct and prolonged.

47


Nasal Cancer

In some areas of the world snuff is inhaled, so that tissues of the nasal
cavity come in contact with the tobacco powder. The earliest report that
links any form of tobacco to cancer was published over two centuries
ago when what were probably nasal cancers were described in several
patients in England who were heavy inhalers of snuff (2). There have
been no systematic evaluations of snuff inhalation and nasal cancer in
the United States, United Kingdom, or other European countries, most
likely because both the sniffing habit and nasal cancer are uncommon,
Sniffing snuff has been reported, however, to be a frequent habit among
Bantu men, whose rates of nasal cancer have been reported to be high (31.
In case-control studies of nasal sinus cancer reported in 1955,80 per-
cent of patients with tumors of the maxillary antrum were prolonged
and heavy snuff users, in contrast to about onethird of Bantu men with
other cancers (4,s). The snuff used by the Bantu is thought to contain
aloe plant ash, trace elements such as nickel and chromium, and other
ingredients in addition to tobacco (6). Snuff use (presumably by inhala-
tion) was reported not to account for the high rates of nasal adenocarci-
noma among furniture makers in studies in England and Denmark, but
evaluations of snuff itself as a risk factor were not undertaken (7,s).

One casecontrol study of cancers of the nasal cavity and paranasal
sinuses in the United States addressed the issue of smokeless tobacco (91.
A total of 193 cases were identified in four hospitals in Virginia and
North Carolina over a lo-year period. No association between sinonasal
cancers and chewing tobacco was found (relative risk 0.7,95-percent con-
fidence interval 0.4-1.5). However, a relative risk of 1.5 was observed for
users of snuff (g&percent confidence interval 082.8). Risk was increased
in snuff users for both adenocarcinomas (relative risk 3.1) and squamous
cell carcinomas (relative risk 1.9) but not for other histologic types
(relative risk 0.6) and was found for both sexes. The implications of the
findings are not clear since the snuff used by the cases and controls was
oral snuff not coming in contact with nasal tissues. Animal experiments,
however, suggest that tumors distant to the site of exposme may l-ealllt
from exposure to constituents of snuff (see the section on animal studies).

An apparent excess of posterior nasal space tumors was reported
among certain tribes in Kenya, and 6 or 12 cases interviewed were
found to be chronic "liquid snuff" users (10). Multiple subsites of the
respiratory tract were considered however, increasing the likelihood of a
chance association No increased risk of nasopharyngeal cancer associ-
ated with snuff use was noted in a casecontrol study in Singapore (11).

Esophageal Cancer

Other tissues that come in contact with constituents of smokeless
tobacco in more dilute concentrations include the linings of the esopha-
gus, larynx (supraglotic portion), and stomach. The results of studies of

48


7I!ABLE l.-Relative Risks of Ektphageal Cancer in
     Pemom Expoeed to Chewing `lbbacco and Snuff:
     Summa@ of Four CaseControl Studies

                                  controle

Fht  zz f3e.x          %          IReldw
AUthtK                   No. Erpud No. Exjmd Risk*

Wynder  Chewing  Any      M    150   20     150   10     2.3
(4         < 1oyrs.             14          4     3.9
        2 iop.              6          6     1.2

Williams  chewing  Level1     M    38    5.2  1,788   5.4    0.9
W    or Snuff  Level2               0          0      -
WYgr  cl=+%  Any       M    183   10.9  2,560   9.0    1.2

      snuff   Any       M          4.4         2.7    1.7

Martinez  t%ewingt Any       M    120    2.5    360   3.6    1.2
(14)                   F     59  `11.9    177   7.3    2.7

*caldatedfrompubliabedrepultifuutpruvidedby~uthur.
tRgtectedtonouamdtea.

cancers of these three sites in relation to smokeless tobacco are inam-
elusive. The studies are gtmemlly of limited power to detect small in-
cxeases in risk, and many did not control for relevant, potentially con-
founding variables. However, some studies of these three cancera do
show au increaseinriskinrelationtotheuseofsmokeless~~.As
shown in table 1, elevated relative risks of esophageal cancer up to
twofold or higher were found in two hospital-based casecontrol studies
in the United States involving 150 and 183 cancer patients (1213) and
one in Puerto Rico (described in the previous section) with 179 casea (I#.
One of the studies by Wynder and colleagues, however, found no
evidence of an incmase in risk with duration of exposure, and all
chewers were also smokers (12). The effect of smoking was not adjusted
for in the other study (13). Another casecontrol study involving 120
black male cases of esophageal cancer was conducted in Washington,
D.C. (15). Few of the cases or controls had used either chewing tobacco
or snuff, suggesting that it did not contribute to the high rates of
esophagealcancerobservedin~eareaFinally,datafromaprospective
(cohort) study of U.S. veterans were analyzed to determine whether
mortalityratesof~cdiseaseswereincreasedinusersofsmokeless
tobacco (16,l. In the absence of smoking, the standardize mortality
ratio for esophageal cancer was found to be 228, but this value was
based on only one death In a cohort study of 12,945 Norwegian and
16,930 American men followed over 10 years, the risk of esophageal
cancer was reported to be significantly increased among men who used

49


chewing tobacco or snuff, after controlling for age, residence, and smok-
ing habits (17,18). Unfortunately, the results of both cohort studies have
been published only as abstracts, so additional details are not available.
Some evidence that the chewing of quids may increase the risk of
esophageal cancer arises from studies in Southeast Asia. In a series of
237 cases of esophageal cancers in Sri Lanka, interview information
from 111 revealed that 90 (81 percent) habitually used betel containing
tobacco leaf (19). This percentage was considerably higher than the fre
quency of betel chewing in the general population (30 percent). Betel
chewing was more common among women. Esophageal cancer also was
more common among women, an unusual observation since this cancer
occurs more frequently among men in almost all areas of the world that
report standardized cancer statistics @Q). Since few women were
reported to smoke or use alcohol, the possibility of an etiologic role of
chewing is increased. However, the potential effects of tobacco as op
posed to other ingredients in the quids cannot be distinguished. In a
case-control investigation in Bombay involving interviews with 305
esophageal cancer patients and nearly 2,000 population controls of age,
sex, and religions similar to all head and neck cancer cases, a 2.5-fold in-
creased risk of esophageal malignancy was observed (p < .Ol) among
nonsmokers who chewed pan, a mixture usually consisting of tobacco,
betel, lime, and other ingredients (21). The excess was higher, however,
among those chewing quids without tobacco (relative risk 3.5) than with
tobacco (relative risk 2.1). A more recent analysis (22) in Bombay based
on 649 patients with esophageal cancer and 649 controls yielded similar
qualitative findings, but the excess among users of pan without tobacco
(relative risk 12.1) was accentuated compared to users of tobacco
containing chews (relative risk 2.81. On the other hand, in an earlier case
control investigation in southern India of several upper digestive tract
tumors, including 93 esophageal cancers, increases in esophageal cancer
risk were much greater among men who used betel with tobacco (c&u-
lated relative risk 11) than without tobacco (calculated relative risk 2) (23,).
The chewing of nass was not associated with esophageal cancer risk
in a case-control study conducted in an area of Iran with among the
world's highest rates for this cancer (24). Of 638 identified cases of
esophageal cancer, interviews were completed with 344 and with 2
neighborhood controls matched to each case. The relative risk associ-
ated with ever using nass was 0.9, with an upper limit of the 95-percent
confidence interval of 1.5, suggesting that any major effect of nass on
the origins of this cancer could be excluded.

Laryngeal Cancer

In a case-control analysis of the interview data from the Third Na-
tional Cancer Survey (TNCS), Williams and Horm compared the prior
use of smokeless tobacco products (in the aggregate) in persons with a

50


variety of individual types of cancer (including laryngeal cancer) with
the history of such use in persons with the remaining cancers thought
not to be related to tobacco use (ZEi,,. Prior experience with smokeless
tobacco was divided into two levels of exposure. The estimates of the
relative risks were controlled for age, race, and smoking. Relative risks
of laryngeal cancer in men of 2.0 and 1.7 were found among individuals
with low and high levels, respectively, of exposure to chewing tobacco
or snuff. These estimates were not significantly different from 1.0. They
are based on 106 cases, 11 with relatively low exposure and 5 with
higher exposure, and 2,102 controls of which 98 had low exposure and
7 1 had high exposure. Only 13 female laryngeal cases were available for
analysis in this study, which was insufficient to provide any meaningful
results.

A case-control study by Wynder and Stelhnan included 387 male
cases of laryngeal cancer and 2,560 hospital controls (13). The percent-
ages that had previously used chewing tobacco and snuff were 11.9 and
3.9, respectively, for the cases, and 9.0 and 2.7, respectively, for the con-
trols. Based on these findings, crude relative risks of 1.4 for chewing
tobacco and 1.5 for snuff were obtained. Neither estimate differs signifi-
cantly from 1.0. No control for smoking or alcohol was done, although
the authors state that cigarette smoking in users and nonusers of chew-
ing tobacco was simiIar.

Interviews with 560 laryngeal cancer patients and 2,000 controls
from the general population of Bombay revealed significantly increased
risks, compared to nonchewers, among chewers of betel without tobacco
(relative risk 2.5) than with tobacco (relative risk 2.6) (21). I.ayngd
cancer was noted to comprise an unusually high proportion of all cancer
diagnoses in a hospital series in eastern India where pan chewing is com-
mon, but no assessment of the role of tobacco was made (26)

Stomach Cancer

Zacho et al. noted that, in Denmark, both gastric cancer and use of
chewing tobacco and snuff are directly related to age, more common in
men than women, more prevalent in rural than urban areas, and in-
versely related to socioeconomic status (27). On the basis of these obser-
vations, they hypothesized that use of smokeless tobacco increases the
risk of stomach cancer. Obviously, other differences among individuals
within Denmark could also explain these findings.

Weinberg et al. conducted a casecontrol study of stomach cancer in a
coal mining region of Pennsylvania (28). Cases who had died of stomach
cancer from 1978 through 1980 were compared with three control
groups: persons who died of other cancers of the digestive system, per-
sons who died of arterial sclerotic heart disease, and persons who lived
in the same neighborhood as the case. All controls were matched to indi-
vidual cases on age, sex, race, and location of residence. Data on the use

51


of various forms of tobacco were obtained by interviewing next&kin or
(for neighborhood controls) the subjects themselves. About 16 percent
of all men in the study had used chewing tobacco. This percentage did
not differ significantly among the cases and the three control groups.
No women in this study had chewed tobacco. This study provides some
evidence to suggest that chewing tobacco does not increase the risk of
gastric cancer, although a small increase in risk could have been missed
due to lack of statistical power.

The case-control analysis of the interview data from the TNCS found
a relative risk of stomach cancer of 1.7 in men in the highest level of use
of chewing tobacco and snuff, no increase in men in the lower use
category, and no increase in women (W). These results are based on 120
male cases, 12 of which were users, and 82 female cases, 2 of which were
users. The power of this analysis to detect a true increase in risk is ob
viously low. The relative risk of 1.7 was not significantly greater than
1.0. In an abstract describing a cohort mortality study of U.S. veterans,
the standardized mortality ratio for stomach cancer among non-
smoking users of smokeless tobacco was 151, but no study details were
provided (16).

Urinary Tract Cancer

Constituents of smokeless tobacco can enter the blood stream, and
some are excreted in the urine. The kidney and bladder are thus poten-
tially exposed to these agents but presuma bly in lower concentrations
than are tissues of the upper aerodigestive tract. In a hospital-based
case-control study in Seattle, Washington, patients who chewed to
bacco were reported to be at nearly a fivefold increased risk of renal
cancer compared to nontobacco users (29). Only 6 percent of the 88 male
cases were chewers. No association between the use of smokeless to
bacco products and either renal cell or renal pelvis cancer was reported
in a case-control study of these tumors in England (39). Among 106
renal cell cancer case-control pairs in this study, 10 cases versus 11 con-
trols had at some time used smokeless tobacco. Among 33 renal pelvis
cancer-control pairs, 2 cases and 3 controls reported ever using smoke
less tobacco products. In a large population-based study in Minnesota
involving 495 cases and 697 controls, a nonsignificantly increased rela-
tive risk of renal cell cancer of 1.7 (95~percent confidence interval 0.5-6.0)
was found among snuff users after adjusting for smoking (31). There
was a deficit in risk, however, associated with ever using chewing to
bacco (relative risk 0.4, 95percent confidence interval 0.1-2.6).

A review of eight epidemiologic investigations revealed no consistent
evidence that the risk of bladder cancer is altered in users of smokeless to
bacco products (table 2) (13,25,32&?). The National Bladder Cancer Study
is the largest of the investigations of bladder cancer considered in this
review (37). Cases for this study were selected through 10 population-

52


TABLE I.-Estimates of Relative Risks of Bladder Cancer in
    Persons Who Have Ever Used Chewing Tobacco and Snuff

                                Relative Risks
              Years
Fist Author       Case         Chewing
(ref.)        Diagnosed Sex     Tobacco     Both     Snuff

Wynder (32)       195783     Male      1.4*               0.7*

Dunham et al. (33)   1958-64     Male     5.3*t     0.9*t -
                    Female     1.1*t -      0.3*t
Cole et al. (34)      196688     Both      1.1*              1.0*

Williams and       1969-71   Malelevel 1            1.61
Horm (25)                 level 2             1.15

                  Female-level 1           0
                       level 2            1.78

Wynder and       1974-75    Males      0.9                0.7
stellman (13)
Howe et al. (36)     1974-76    Males      0.9
Hartge et al. 137)    1977-78    Males      1.02            0.77t

o Estimated from published report.
t Based on analysis of nonsmokers only.

based cancer registries in the United States. Controls were a random
sample of the same population from which the cases came. Information
was obtained from interviews of 2,982 cases and 5,782 controls. Analy-
ses of smokeless tobacco use were restricted to the 340 cases and 1,227
controls who claimed never to have smoked cigarettes. Of these, 11 per-
cent of the cases and 10 percent of the controls had ever used chewing
tobacco, and 3 percent of the cases and 4 percent of the controls had
ever used snuff. The relative risks of bladder cancer in users of chewing
tobacco and snuff were estimated to be 1.0 (0.7-1.5) and 0.8 (0.4-1.6).
respectively.

Wynder et al. conducted a hospital-based study of 300 male bladder
cancer cases (j72). Eleven percent of the 300 cases and 8 percent of the
300 hospital controls had ever used chewing tobacco; 2 percent of the
cases and 3 percent of the controls had used snuff. The percentage of
users was not significantly different in cases and controls, and no
attempt was made to analyze the data further.

Dunham et al. interviewed 493 bladder cancer patients and 527 hospi-
talized controls in New Orleans (33). Among nonsmokers, there was an
increased relative risk associated with chewing tobacco use among
males but a deficit in risk associated with snuff use among females, but
the numbers of cases involved were small (four males and three
females).

Cole et al. interviewed 470 cases from the Boston area and 500
population-based controls (34). Forty-six of the cases had used chewing

53


tobacco and three had used snuff. Based on the prior experience with
smokeless tobacco in the controls (controlling for age and sex), 42.3 and
7.9 cases would have been expected to have used chewing tobacco and
snuff, respectively. Some increase in the risk of bladder cancer was
found in the TNCS survey, but none of the risks from this study are sig-
nificantly different from 1.0 (table 1) (2.5). In addition, no evidence of a
dose response is seen.

In a second hospital-based casecontrol study (13) of similar design to
the first (32), Wynder and St&man found that 8 percent and 1.9 percent
of 586 cases had used chewing tobacco and snuff, respectively, com-
pared to 9 percent and 2.7 percent of 2,560 controls who had used these
two products. When analyses were restricted to nonsmokers in a con-
tinuation of this study, a significant excess risk of bladder cancer was
associated with snuff use among women, but only 3 of 76 cases were
users (35).

A population-based casecontrol study was conducted in three Cana-
dian provinces by Howe et al, (3@. Controls were matched to individual
cases on neighborhood, age, and sex. The ratio of male pairs discordant
for the use of chewing tobacco was 29134, giving a relative risk of 0.9
(95~percent confidence interval, 0.5-1.6). This estimate was not altered
by controlling for smoking. No female cases or controls gave a prior
history of use of smokeless tobacco.

In Denmark, 165 male and 47 female patients with cancer of the uri-
nary bladder from a hospital serving a specific geographic area were
interviewed, as were geographically-matched controls (3&Z?). The esti-
mated relative risk associated with tobacco chewing was 2.0 (1.2-3.4)
based on 39 exposed cases. In a logistic model containing variables for
tobacco chewing, smoking, and other major correlates of bladder can-
cer, the relative risk associated with chewing was 1.7 and statistically
significantly higher than 1.0. The authors estimated that tobacco chew-
ing might account for 9 percent of the bladder cancer diagnoses in the
area.

Although two studies did report elevated relative risks associated
with smokeless tobacco use, on balance these studies provide little evi-
dence to suggest that smokeless tobacco alters the risk of bladder
cancer. It is possible that a small increase in risk has not been detected
by the studies not reporting increases due to lack of statistical power.

Other Cancers

All other organs of the body are likely exposed to even lower concen-
trations of products of smokeless tobacco via the blood.
In a large prospective study in Norway, 16,7 13 individuals were inter-
viewed to obtain information on the use of tobacco and alcohol and were
followed up for development of pancreatic cancer (40). Sixty-three per-
sons in the cohort developed this neoplasm during a lo-year followup.

54


After controlling for cigarette smoking and alcohol consumption, a rela-
tive risk of 2.9 was observed in regular users of chewing tobacco or snuff
(compared to nonusers). The 95percent confidence limits of this value
include 1.0. Risk was greater in regular users than former or occasional
current users, and a trend of increasing risk with amount used was of
borderline statistical significance (P=.O6). The case-control analysis of
the interview data from the TNCS (24) with respect to pancreas cancer
is based on only 91 male cases (3 exposed to smokeless tobacco) and 85
female cases (none exposed); and although no increase in relative risk of
pancreatic cancer in relation to smokeless tobacco was observed, the
power of this study to detect such an increase is low.

Other cancer sites were found to be related to the use of smokeless
tobacco in the casecontrol analysis of the interview data from the
TNCS (24). Relative risks for colon cancer at low and high levels of expo-
sure were found to be 0.9 and 1.5 for men and 0.4 and 2.0 for women,
respectively. Relative risks of cervical cancer in users of these two levels
of exposure were 3.1 and 2.3. No studies have been conducted to con-
firm or refute these findings. In view of the large numbers of possible
associations investigated, these results should be considered of value
only in generating hypotheses for further investigation.

Summary

The epidemiologic studies showing an association between the use of
snuff and oral cancers indicate that topical exposure of tissues to
smokeless tobacco can cause cancers at the site of the exposure. Case
reports of neoplasms developing in the ear and nose of individuals who
used snuff at these sites raise the possibility that direct exposure may
increase the risk in locations besides the oral cavity. Other tissues that
come in contact with constituents of smokeless tobacco in more dilute
concentrations include the linings of the esophagus, larynx (supraglotic
portion), and stomach. Results of studies of cancers of these three sites
in relation to smokeless tobacco are inconclusive; many are of limited
power to detect small increases in risk and did not control for relevant,
potentially confounding variables. However, some studies of these
three cancers do show an increase in risk in relation to the use of smoke
less tobacco. Constituents of smokeless tobacco can enter the blood-
stream, and some are excreted in the urine. The kidney and bladder are
thus potentially exposed to these products and their metabolites but
presumably in lower concentrations than are tissues of the upper aero
digestive tract. Evidence suggests that the risk of bladder cancer is not
altered to any large extent in users of smokeless tobacco products, but
results from studies of kidney cancer are inconsistent. Information
regarding the risks of other cancers in relation to smokeless tobacco use
is sparse.

55


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  of Iran: Results of a casecontrol study. Br. J. Cancer 39 293-309,1979.
(25) WiIliams. R.R., and Horm, J.W. Association of cancer sites with to
  bacco and alcohol consumption and socioeconomic status of patients.
  Interview study from the Third National Cancer Survey. J. Natl.
  Cancer Inst. 58: 525-547, 1977.
(26) Sarma, S.N. A study into the incidence and etiology of cancer of the Iarynx
  and adjacent parts in Assam. Indian J. Med. Res. 46 525-533, 1958.
(27) Zacho, A., Nielsen, J., and Larsen, V. On the consumption of unburned
  tobacco in patients with cancer of the stomach. Acta Chir. Stand. 134:
  272-274, 1968.

(28) Weinberg, G.B., KuIIer, L.H., and St&r, P.A. A case control study of
  stomach cancer in a coal mining region of Pennsylvania. Cancer 56:
  703-713, 1985.

f29) Bennington, J.L., CampbeII, P.B., and Ferguson, B.R. Epidemiologic
  studies of carcinoma of the kidney, II. Association of renal adenocar-
  cinema with smoking. Cancer 22 821-823.1968.
(30) Armstrong, B., Garrod A., and Doll R. A retrospective study of renal
cancer with special reference to coffee and animal protein consumption.
  Br. J. Cancer 33: 127-136, 1976.

(31) McLaughlin J.K., Mandel J.S., Blot, W.J., Schuman, L.M., MehI, E.S.,
  and Fraumeni, J.F., Population-based casecontrol study of renal ceII car-
  cinoma. JNCI 72: 275-284, 1984.

(32,) Wynder, E.L., Onderdonk, J., and Man@ N. An epidemiological inves-
  tigation of cancer of the bladder. Cancer 11: 1388-1406, 1963.
&J Dunham, L.J., Rabson, A.S.. Stewart, H.L., Frank, A.S., and Young, J.L.
  Rates, interview and pathology study of cancer of the urinary bladder in
  New Orleans Louisiana. J. Natl. Cancer Inst. 41: 683-709, 1968.

57


(34) Cole, P., Monson, R.R., Haning, H., and Friedell, G.H. Smoking and
  cancer of lower urinary tract. N. Engl. J. Med. 284: 129-134, 1971.
(35) Kabat, G.C.. Dieck, G.S., and Wynder, E.L. Bladder cancer in non-
  smokers. Cancer 57: 362-367, 1986.

(36) Howe, G.R., Butch, J.D., Miller, A.B., Cook, G.M., E&eve, J., Morri-
  son, B., Gordon, P., Chambers, L.W., Fodor, G., and Winsor, G.M.
  Tobacco use, occupation, coffee, various nutrients, and bladder cancer.
  JNCI 64: 701-713. 1980.

(37) Hartge, P., Hoover, R., and Kantor, A. Bladder cancer risk and pipes,
  cigars, and smokeless tobacco. Cancer 55: 901-906, 1985.
(38) Mommsen, S., Aagaard, J., and Sell, A. An epidemiologic study of blad-
  der cancer in a predominantly rural district. Stand. J. Urol. Nepbrol. 17:
  307-312, 1983.

(39) Mommsen, S., and Aagaard, J. Tobacco as a risk factor for bladder
  cancer. Carcinogenesis 4: 335-338, 1983.
(40) Heuch, I., Kvale, G., Jacobsen, B.K., and Bjelke, E. Use of alcohol,
  tobacco and coffee, and risk of pancreatic cancer. Br. J. Cancer 48:
  6374x3,1983.

CHEMICAL CONSTITUENTS, INCLUDING
CARCINOGENS, OF SMOKELESS TOBACCO

Chemical Composition of Smokeless Tobacco

`RI date, at least 2,500 known compounds have been identified in pro
cessed tobacco (1). Besides polysaccharides and protein tobacco con-
tams Nicotzizna alkaloids (0.5-5.0 percent), alkanes (0.1-0.4 percent),
&penes (0.1-3.0 percent), polyphenols (0.5-4.5 percent), phytosterols
(0.1-2.5 percent), carboxylic acids (0.1-0.7 percent), aromatic hydra
carbons, aldehydes, ketones, amines, amides, nitriles, N- and 0-hetero
cyclic compounds, chlorinated organic compounds, alkali nitrates
(0.2-5.0 percent), and at least 30 metal compounds (83).
The most important habituating agent in tobacco is nicotine, the ma-
jor representative of the alkaloids that constitute 0.5-5 percent of the
leaf depending on the strain, variety, and agricultural practices that are
employed during the tobacco cultivation. In total, the alkaloids are
composed of 85 to 95 percent nicotine (4) and of other major alkaloids
such as the secondary amines nornicotine, anatabine, and anabasme
with lesser amounts of cotinine, myosmine, nicotyrine, 2,3'-dipyridyl,
and N `-oxynicotine (5).

Carcinogens in Smokeless Tobacco
At present, three classes of carcinogzIls are known to occur in smoke
less tobacco products: N-nitrosamines, polynuclear aromatic hydrocar-
bons (PAH), and polonium-210 ( 210Po). Although chemical-analytical

58


FIGURE l.-N-Nitroeamhes in Smokeless `Ibbacco

1. Volatile Nitrosamines

' ' N-NO
R-----

R = -a-l,  NDMA
R = -C,H,  NDEA

2. Nonvolatile Nitrosamines

HO-CH,-Cl-l,,
HO-CH+H, , N-NO

NDEIA

n
  N
A0

NPYR

0
  N
JJO

NPIP

A0

NMOR

H&-N-R           R= -COOH   NPRO    R= -COOH    NPIC
  LO        R= -CH&OOH NPYRAC R= -CH&OOH NPIPAC

R = -CH,-CH,-COOH    NMPA
R = -CH,CH,-CH,-CCOH NMBA
3. Tobacco-Specific Nitrosamhee

         NNN          NAT          NAB
QLEc:3 @L":c.3
                   NNK               NNAL
data are lacking, some smokeless tobacco mixtures contain or are sus-
pected to contain traces of cadmium and nickel compounds (6). formal-
dehyde, and coumarin, all of which are known animal carcinogens (78).

N-Nitroeamhea

Tobacco leaves contain an abundance of amines in the form of pre
teins and alkaloids. `lbba~ also contains up to 5 percent nitrates and
traces of nitrite. Thus there is the potential for the formation of
N-nitrosamines from the nitrate, nitrite, and amines during the process-
ing of smokeless tobacco products. In tobacco, we distinguish between
volatile nitrosamines, nonvolatile nitrosamines, and tobacuxqAfic
nitrosamines (figure 1). With the exception of some N-nitrosamino

59


FIGURE 2.-Formation of `Ibbacco-Specific Nitrosamhes

NICOTINE       NORNICOTINE ANARASINE   ANATABINE

NITROSATION

NNAL                  NNK         NNN       NAB        NAT

acids, the nitrosamin es in tobacco are animal carcinogens that are
formed after harvesting of the tobacco during curing, fermentation,
and/or aging. The N-nitrosamin o acid, N-nitrosoproline, occurs in pro-
cessedfoodandcanalsobeformedinhumans by endogenous nitrosation
of proline. This nitrosamino acid is not carcinogenic on the basis of pres-
ently available data (912). Table 1 s ummarizes the available data for the
volatile nitrosamin es in smokeless tobacco. Only one of the volatile
nitrosamines, NDMA, has been found in U.S. looseleaf tobacco, but
four nitrosamines have been found in American snuff. N-Nitrosomor-
pholine is formed during tobacco processing or aging from morpholine,
a cyclic amine that is not known to occur in uncontaminated tobacco
(13,14) but originates from packing materials and/or flavor additives.
Table 2 lists the presently known nonvolatile nitrosamines in smokeless
tobacco. N-Nitrosod.iethanolamine (NDELA) in U.S. tobacco originates
primarily from residues on tobacco leaves of the sucker-growth inhibi-
tor maleic hydrazidediethanolamine (MH-30). Use of this formulation of
the agricultural spray was banned in the United States in 1981, and the
concentration of NDELA in smokeless tobaccos has markedly de
creased since then (14,15).

Figure 2 presents the formation of the tobaccospecific N-nitrosamines
(TSNA) from the alkaloids. There is progressive nitrosation of the alka-
loids during curing and processing and even during the shelf life of the
commercial products (16). Table 3 summar&es the presently available
quantitative data for four out of five TSNA's that are present in smoke
less tobacco. The nitrosamines are detectable in snuff and tobacco prod-
ucts from various parts of the world. Analyses of Swedish snuff brands
manufactured between 1980 and 1985 have revealed a significant
decrease of the levels of TSNA; such a trend has not been observed for
U.S. snuff brands (14,16,17). It has been suggested that the lowering of
TSNA levels in Swedish snuff brands is due to better control of the bac-
terial content of the tobacco products. Reduced bacterial activity will
probably reduce nitrite levels and, consequently, inhibit nitrosamine

60


TABLE l.-Volatile Nitroaminea in Smokeless `Ibbam (ppb)*

Pruduct

NDMA

NPYR

NPIP

NMOR

Fleference

U.S.
Looseleaf t
Snuff

ND - 380 (4)
ND - 215 (26)

ND - 1.2 (4)
ND - 291 (16)

ND    (4)       ND - 2.5 (4)
ND - 107 (16)      ND-696 (26)

1q14,1794
13y4,17,20,
29,%37

Sweden
Chewing Tobacco
Snuff

ND - 0.6 (4)
ND-60 (53)

0.9 - 3.7 (4)
ND - 210 (27)

ND    (2)       ND - 0.8 (2)         1736
ND - 0.5 (37)      ND - 1.2 (53)        14,17,36

Canada
Snuff

23 - 72.8 (2)

321 - 337 (2)

14

Denmark
Chewing Tobacco

Norway
Chewing Tobacco

India
Chewing Tobacco

U.S.S.R.
Nass$

ND - 8.6 (6)

7.0 - 25.5 (6)

ND    (4)       ND - 32.8 (6)

17.36

84.0 - 280 (2)

2.8 - 15 (2)       28-37 (2)

37 -220 (2)

17

ND - 0.56 (4)

ND     (4)           14

ND    (4)

14

1.55 - 4.48 (4)

ND    (4)

1.74 - 8.82 (4)

    * Number m parentheses. number of samples analyzed
   t One sample also contained 8.6 ppb NDEA.
e    $ Also contained ND 69.6 NDEA /Ml.


i?   TABLE 2.-Nonvolatile Nitr osamines in Smokeless Tobacco (ppb)*

Tobacco
product

NDELA      NMPA

NMBA

NPRO

NPYRAC

NPIC

NPIPAC

Reference

U.S.
Looseleaf     224 - 680 (3)


Snuff       160 - 6,800   1,250 - 7.420
            (13)        (51

Sweden
Snuff        230 - 390    510 _ 4,400
            (8)        (12)

Canada
Plug Tobacco    110 (1)
Snuff     1,180 - 2,720 (3)
Germany
Plug Tobacco    50 (2)
Belgium
Chewing              1,600 (1)
Tobacco

U.S.S.R.
Nass

India
Chewing
Tobacco

40 (4)


30 - 110 (4)

        450 - 463 (2)


120 - 2.240    500 _ 50.900    ND - 2,000
(5)        (13)        (5)


ND _ 260    890 - 29,500   100-300
(12)        (12)        (5)


         100 (1)
      8,800 - 16,600 (2)

500 - 700 (2)

100 (1)     3,300 (1)     200 (1)



      ND - 180 (4)

190 - 410 (4)

ND - 6.100
(5)

ND - 5,560
(12)

100 (1)

       13J4p.M


ND - 1,500   1315,34,
        3Jm

100 - 200    14,15,*40
(5)



            14
            14



            14



200 (1)        40




            14



            14

o Number in parentheses. number of samples analyzed


TABLE 3.-`Ibbacco-Specific N-Nitrosamhes in Smokeless Tobacco (ppb)'

Product

NNN

NNK

NAT

NAB

Reference

U.S.
Looseleaf
Plug lbbacco
Snuff

Sweden
Snuff
Plug Tobacco
Canada
Snuff

Norway
Snuff

Denmark
Snuff
Chewing Tobacco
Germany
Plug lbbacco
Snuff

U.S.S.R.
Nass

Indii
Chewing Tobacco
Belgium
Chewing Tobacco

620-8.200 (9)
3,400-4,300 D)
1,600-135,000 (21)

3.050-154.000 (34)
350-2,090  (3)

50,420-79,100 (2)

13,000-29,000 (2)

4.460-8,000 (3)
210-1.400 (4)

1,420-2,130 (2)
6,080-6,700 (2)

120-520   (4)

470-2,400 (5)

7,380 (1)

ND-380   (4)      130-2,300 (5)

loo-13,600 (21)     1,560-338,000 (21)

510-2,950 (34)
ND-240   (3)


3,200-5,800 (2)

1,600-21,400 (34)
6%1,580 (3)

152.000-170,000 (2)

2,700-3,900 (2)

9,100-16,000 12)

1,350-7,030 (3)
ND-210   (4)


30-40   (2)
1,500-1,540 (2)

20-130   (4)


130-230   (4)


   970 (1)

2,680-6.170
300-2.80-O 1:;


330-500   (2)
3,920-4.370   (2)


32-300    (4)


300-450   (4)


     130 (1)

ND-140 (5)

M-6,700 (12)

110-150 (19)
ND-100 (3)

4,000-4,800 (2)

l,OOO-2.400 (2)

ND-60   (4)


30-50   (2)

8-30   (4)

30-70   (4)

14,17,41,42
    43
614,16;17,384243

14.1~1738
l/17

14

17

16
17

14
16

14

14,41

38

E   * Number in parentheses. number of samples analyzed.


TABLE I.-JMimated Exposure of U.S. Residents to Nitmsamines*

source of
Exposure

Nitrosamines

Primary Exposlue   Daily Intake
   Route       ug/Person

Beer

Cosmetics

Cured Meat;
Cooked Bacon
Scotch Whiskey
Cigarette Smoking

NDMA

NDELA


NPYR

NDMA
VNAt
NDELA
  NNN
  NNK
NAT+NAB

  Ingestion
Dermd Absorption

Ingestion
Ingestion
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation

0.34

0.41

0.17

0.03

0.3
ii::
2.9 >  16.2
1.2

Snuff DippingS

  VNA       Ingestion       3.1
NDELA      Ingestion        6.6
  NNN       Ingestion       75.0
  NNK       Ingestion       16.1
NAT+NAB     Ingestion       73.4 > 164.5

o From the National Research Council /lgl. amended by data for snuff dipping 1131. In addition. it has been est.&
lished that u
NDMA and r n inhalation of the air in cars with new leather upholstery daily exposure amounts to 0.50 yg of
      .20 ug of NDEA 1181.
t VNA. NDMA + NEMA + NDEA + NPYR 1371.
1 Bnmnemann et al. 113/; average values from the leading five U.S. finecut tobaccos used for snuff dipping in 1981;
assumed daily consumption 10 g/day of snuff: VNA = NDMA + NPYR + NMOR.

formation (17). NNK and NNN are powerful carcinogens in mice, rats,
and hamsters, NAB is moderately carcinogenic, and NAT is inactive in
rats in doses up to 9 mmolkg (table 3, page 82) 13).
The daily exposure of an "average" snuff dipper to carcinogenic
N-nitrosamin es exceeds by at least two orders of magnitude the esti-
mated exposure of U.S. residents to nitrosamines in products other
than tobacco products (table 4) (18,19). Furthermore, the concentrations
of carcinogenic nitrosamines in snuff exceed very signifi~tly the per-
missible limits for individual nitrosamines in consumer products
(table 5).
During snuff dipping or chewing of tobacco, the TSNA's are ex-
tracted by the saliva. Consequently, the saliva of snuff dippers is
reported to contain 5.0-420 ppb of NNN, up to 96 ppb of NNK, and
6.6-555 ppb of NAT (16). The saliva analyses of Indian tobacco chewers
showed the presence of 1.2-220 ppb of NNN, 3.2-51.7 ppb of NAT, and
up to 2.3 ppb of NNK (20,21). Recently, three additional TSNA's have
been isolated from U.S. commercial snuff: 4-(methylnitrosamino)-l-
(3-pyridyhbutanol-1 (NNAL), 4-(methylnitrosam.ino)-1-(3-pyridyl)
butenel (NNO), and 4-(methytitrosamino)-4-(3-pyridyl)butanol-1 (Red
NNA) (figure 3) (22). Additional amounts of TSNA's are most likely also
formed by nitrosation processes that occur in the oral cavity during
chewing (1422,23).

64


TABLE 5.-Permissible Limits for Individual
       N-Nitrosamines in Consumer Products

Product

Permissible Limit
wb Whz)

Agency

Bacon (Meat)

Beer
Rubber Nipples of
Baby Bottles

5              USDA*

5             FDA?


10             FDA$

Range of Individual Nitrosamines Present in Snuff Tobaccos
              ppb bdcd

NNN                  5,800 - 64.000

NNK                   100 - 3,100

NAT                   3,300 - 215,000

NAB                    200 - 6,700

NDELA                  160 - 6,800

Range in the leading
5 US. brands (1984-85)


Range in 13 U.S. brands
   (1980-1985)

o No "confirmable levels of mtrosammes' (441.
t Regulation set for N-nitroscdimethylsminine 14.9
$ Regulation set for any mdividual volatde N-nitrosamine (461

Polynuclear Aromatic Hydrocarbons
A number of naphthalenes have been identified in processed tobacco
and especially in Latakia, which is flavor enriched by treatment with
wood smoke (24,,25). While smoking tobaccos were found to contain
300-5,000 ppb of phenanthrene, 1 N-4.200 ppb of anthracene, 76-1,800
ppb of pyrene, 15-14,000 ppb of fluoranthene, and 8.5 ppb of
benzo(a)pyrene (BaP) (26,27), analyses of British snuff in 1957 showed
levels of 260 ppb of pyrene, 335 ppb of fluoranthene, and 72 ppb of BaP
(28). In the five most popular snuff brands in the United States that
were analyzed in 1985, BaP ranged from C 0.1 to 63 ppb (29).

Polonium-210

This alphaemitting element has long been incriminated as a human
carcinogen (30). The levels of 21oPo in dozens of U.S. and foreign cigar-
ette tobaccos were between 0.1 and 1.0 pCi/g (31). In recent samples of
the five leading U.S. snuff brands, 21oPo ranged from 0.16 to 1.22 pCi/g
(29). It appears that 21oPo in tobacco leaves stems partially from certain
types of fertilizers and airborne particles that are taken up by the tri-
chomes (glandular hair) of the tobacco leaf (3133).

Summary

In processed tobacco, more than 2,550 chemical compounds have
been identified. Among these are traces of known carcinogens such as

65


FIGURE 3.-`Ibbaax Specific N-Nitrwamines in Snuff
      U.S. Brands, 1985

Nitmmamines

  Relative
Carchogenicity
  in Rats*

Concentration ia Snuff
    We)
  (Dry Weight)

A         B

NNN CP
  Q Co

NAB

cl"
Q io

NAT

OH

CH3
h-NO

+++          3.3        64

+

-t          44         215

ybi 3
NO         +++

+

?

?

1.1

6.7

1.8

0.3

trace$

1.3

3.1

0.14

trace*

1.8

o + + + `Xmors with 1 mm&kg: + tumors with 9 mmollkg; (for type of tumors induced se table 4. page 381;
+ insignificant number of tumors with 9 mmollkg: ? not tested.
t IsoM.ed amount.3 only.
$ < 0.01 upig.

PAH, 21OP0, and N-nitrosamines. The most prevalent organic carcine
gas are the t.obawespecific N-nitrosamines that are formed from the
Nicotiunu alkaloids during the processing of tobacco leaves. Their con-
centrations in snuff exceed the levels of nitrosamines in other consumer
products by over one hundredfold. During snuff dipping or chewing of
tobacco, the nitrosation process continues within the mouth stimulated
by oral bacteria.

66


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(31) Harley, N.H., Cohen, B.S., and `Iso, T.C. Polonium-210: A questionable
risk factor in smoking-related carcinogenesis. Banbury Report 3:
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(32) Martell, E.A. Radioactivity of tobacco trichromes and insoluble cigar-
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(33) `l%o, T.C., Harley, N.H., and Alexander, L.T. Source of lead-t&in and
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(34) Brunnemann. K.D., Scott, J.C., and Hoffmann, D. N-Nitrosoproline, an
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(35) Palladino, G., Adams, J.D., B runnemann, K.D., Haley, N.J., and
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(36) &terdahl, B.G., and Slorach, S.A. Volatile N-nitrosamines in snuff
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  759-762, 1983.

(37) Brunnermum, K.D., Yu, L., and Hoffmann, D. Assessment of carcino
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(39) Ohshima, H. Identification and occurrence of new N-nitrosamino acids
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  cinostatic Agents Containing Nitrogen-Nitrogen Bonds, Harper's
  Ferry, West Virginia, May 17-21, 1985.
(40) Oh&ma, H., Nair, J., Bourgade, M.C., Friesen, M., Ganeen, L, and
  Bar&h, H. Identification and oczaurence of two new N-nitrosammo acids
  in tobacco products: 3jN-nitrosoN-methyiaminoylamino)propionic acid and
  4-(NnitxosoNmethylaminolbutyric acid Cancer L&t. s 153-162,1985.
(41) Hoffmann, D., Hecht, S.S., Omaf, R.M., Wynder, E.L., and `lbo, T.C.
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(42) Munson, J.W., and Abdine, H. Determination of N-nitrosonomiwtine in
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(43) Adams, J.D., Bnmnemann, K.D., and Hoffmann, D. Rapid method for
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  1983.

(44) U.S. Department of Agriculture, Food Safety and Quality Service.
  Nitrates, nitrites and ascorbates (or isoascorbah) in bawn. Fed. Reg. &
  20992-20995, May 16,1978.

1&J U.S. Food and Drug Administration. Dimethyl nitrosamine in malt
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                     a `on. Action levels of total volatile
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69


Abbreviations

BaP
NAB

NAT

ND
NDEA
NDELA
NDMA
NMBA
NMOR
NMPA
NNAL
NNK
NNN
NNO
NPIC
NPIP
NPIPAC
NPRO

NPYR
NPYRAC

PAH
2lOPo

Red NNA
TSNA

Benzo(a)pyrene
N `-Nitrosoanabasine
N `-Nitrosoanatabine
Not detected
Nitrosodiethylamine
Nitrosodiethanolamine
Nitrosodimethylamine
Nitrosomethylbutyric acid
Nitrosomorpholine
Nitrosomethylpropionic acid
4-(Methyhr.itrosamino)-1-(&pyridyl)-1-butanol
4-(Methyhritrosamino)-l-(3-pyridyh-1-butanone
N `Nitrosonomicotine
4-(Methylnitrosamino)-l-(3-pyridyl)butenel
Nitrosopipecolic acid
Nitrosopiperidine
Nitrosopiperidine-acetic acid
Nitrosoproline
Nitrosopyrrolidine
Nitrosopyrrolidineacetic acid
Polynuclear aromatic hydrocarbons
Polonium-2 10
4-(Methyhritrosamino)-4-(3-pyridyh-1-butanol
Tobaccospecific nitrosamines

METABOLISM OF CONSTITUENTS
OF SMOKELESS TOBACCO

The tobaccospecific nitrosamines 4-(methylnitrosamino)-l-(3-pyridyl)-
1 -butanone (NNK) and N `-nitrosonornicotine (NNN) are quantitatively
the major known carcinogens that are present in snuff and other types
of smokeless tobacco. Molecular changes that are induced in the genetic
material of tobacco chewers are most likely to arise from the metabo
lism of these two nitrosamin es. Although present in similar quantities,
N'nitrosoanabasine (NAB) and N'-nitrosoanatabine (NAT) are less car-
cinogenic than NNK and NNN and are less likely to play an important
role in the induction of oral cancer in man. Some snuff products contain
considerable amounts of N-nitrosomorpholine (NMOR) and N-nitro

70


FIGURE l.-Metabolic Pathways of NNK

sodiethanolamine (NDELA); the former is a potent carcinogen. The
levels of benzo(ab>yrene (BaP) and 2loPo in snuff tobacco are low com-
pared to those of the nitro samines (see previous section). This section
will focus on the routes of metabolic activation of the compounds that
are most likely to be involved in the induction of tumors that are related
to snuff use-NNK, NNN, and NMOR.

Metabolism of NNK

The overall metabolic scheme for NNK, as determined by in uivo and
in vitro studies in F-344 rats, Syrian golden hamsters, and A/J mice, is
illustrated in figure 1 (l-4). A key feature of this metabolic scheme is the
conversion of NNK to the alpha-hydroxy intermediate 4, which is un-
stable and undergoes spontaneous conversion to the keto aldehyde 8
and, most likely, methyl diazohydroxide 9. The latter is a methylating
agent that is well known for its ability to methylate DNA forming
7-methylguanine, 06-methylguanine, 4-methylthymidine, and a spec-
trum of other products (5). Among these, O&methylguanine, which is
generated from precursors such as N-methyhritrosourea (NMU) or
N-nitrosodimethylamine, has been unequivocally shown to be able to in-
duce miscoding during DNA replication, and the resulting point muta-
tion is sufficient to activate proto-oncogenes (6,7). Many studies have
demonstrated a correlation between 06-methylguanine persistence in rep
licating tissues and the initiation of the carcinogenic process, although it
is clear in other cases that additional factors are also involved (89).

71


FIGURE 2.-Scheme Linking Nicotine to Formation of the
     Promutagenic DNA Adduct, 06-Methylguanine

       TOBACCO PROCESSING             METABOLIC
           OR            PCTIVbTIOI(- [CHSN=NOtl] - 7-YETWLGUANINE

         CIGARETTE                       YETHYLOIAZO-  06-YETHYLGUANINE

          SYOKING                        HYDROXlDE        IN DNA
NICOTINE                  NNK
                      -

Recent studies have demonstrated that NNK can methylate target
tissue DNA of rats; 7-methylguanine and 05methylguanine have been
detected in the DNA of rat lung, nasal mucosa, and liver but not in the
nontarget tissues, kidney, and esophagus (1014). These studies have
also shown that, in the case of NNK, 06-methylguanine formation alone
is not sufficient for tumor induction since persistent levels of 06-methyl-
guanine in the lung were less than those observed upon treatment with
equivalent quantities of N-nitrosodimethylamine, but the latter did not
induce lung tumors (13). It is clear from these, and related studies with
NNN, that DNA adducts are also formed via pyridyloxobutylation or
related processes. Regardless of the mechanism, it is significant that
NNK causes DNA methylation; this creates a mechanistic link between
nicotine, the habituating factor in tobacco, and 08methylguanine for-
mation in DNA, as illustrated in figure 2. Immunoassay methods are
currently being developed to detect 06-methylguanine in the exfoliated
oral cells of snuff dippers. Its presence can be inferred from the animal
studies that are discussed above and by the demonstration that human
tissues, including buccal mucosa, can metabolize NNK by alpha-
hydroxylation (15). In this respect, it is significant that injection of
Syrian golden hamsters with the methylating agent MNU, combined
with irritation of the buccal mucosa, resulted in the induction of oral
cavity tumors (16).

The pathway of NNK metabolism leading to the alpha-hydroxy inter-
mediate 3 is also considered to be important in NNK carcinogenesis.
This pathway gives rise to the electrophilic diazohydroxide 7. The prop
erties of this intermediate have been investigated by using a model
compound, 4-(carbethoxynitrosamino)-l-(3-pyridyl)-l-butanone
(CNPB). Generation of 7 from CNPB is strictly analogous to the well-
known ability of NMU to generate methyl diazohydroxide. Mutagen-
icity assays in S. typhimurium of CNPB have shown that it is more
mutagenic than NMU (17). Chemical model studies have demonstrated
that it modifies the NZ-position of deoxyguanosine (18). This adduct and
other adducts that may be formed from the diazohydroxide 7 and
related intermediates are likely to play an important role in tumor in-
duction by NNK. Autoradiographic studies have demonstrated that
radioactivity from [carbonyl-14C]NNK is firmly bound to target tissues
of rats and hamsters (4,19) and to tissues of the marmoset monkey (20).

72


FIGURE 3.-Metabolic Pathways of NNN

A third key feature of NNK metabolism is its rapid conversion in vivo
and in cultured tissues from experimental animals and humans to its
reduced form, NNAl, which has similar tumorigenic activity to that of
NNK (1,34,15,21). NNAl is slowly metabolized as indicated in figure 1
and also by reconversion to NNK. Like NNK, it methyl&es DNA in
vitro and in rho. While the full details of the NNK-NNAl equilibrium
have not yet been elucidated, it is clear that NNAl can act as a cir-
culating source of NNK metabolites. It may play an important role in
tissuespecific carcinogenesis by NNK.

Metabolism of NNN

Metabolic pathways of NNN are illustrated in figure 3. These path-
ways have been elucidated by in uiuo and in vitro studies in rats,
hamsters, and mice @,3,22-29). The stable met&o& NNN-l-N-oxide (1)
has tumorigenic activity somewhat less than that of NNN but is still an
effective carcinogen in F-344 rats (30). Metabolism of NNN to the 2'-
and 5 `-hydroxy intermediates 2 and 5 constitutes a major pathway in
uiuo and in vitro in experimental animals, human liver microsomes (31),
and cultured human tissues, including buccal mucosa (15). Of particular
interest is the ability of two NNN target tissues, lingual mucosa and
esophageal mucosa, to carry out preferential 2 `-hydroxylation of NNN
@7,32). The intermediate that is formed by 2'-hydroxylation of NNN is
diazohydroxide 8, which is identical to that formed by methyl hydroxy-
lation of NNN (7, figure 1). As described above, this intermediate is

73


FIGURE I.-Metabolic Pathways of NMOR

IO        II

highly mutagenic, and this or related intermediates appear to play an
important role in carcinogenesis by both NNN and NNK. The inter-me
diate 9 is significantly less mutagenic than 8 in S. typhimutium (33). and
various lines of evidence indicate that it is less important in NNN
tumorigenesis than is 8 (33,3#. Autoradiographic studies have demon-
strated that radioactivity from [2'-14C]NNN is bound to tissues of mice,
rats, and marmoset monkeys (ZYJ35-37). Immunoassays are currently
being developed for the putative DNA adducts that are produced by
2 `hydroxylation of NNN and methyl hydroxylation of NNK; it will be
important to assess the levels of these adducts in the exfoliated oral
cells of snuff dippers. Their levels may relate to the susceptibility of in-
dividuals to the effects of smokeless tobacco. The metabolic pathways
that lead to these intermediates can be affected by alcohol consumption
and dietary components &?2,38#3).

Metabolism of NMOR

The metabolic pathways of NMOR are illustrated in figure 4. These
have been elucidated by in vitro and in uiuo studies in rats (44-47). Struc-
ture activity studies bad shown that 3-hydroxylation of NMOR, leading

74


to intermediate 4, was likely to he important in NMOR carcinogenesis
(48). This pathway could result in the formation of glyoxaldeoxyguano
sine adducts (49); 2-hydroxylation of NMOR also occurs, giving the
mutagenic product 2. The latter also forms glyoxaldeoxyguanosine
adducts (50). These adducts, which are likely to have miscocling proper-
ties, also should he present in the DNA of snuff dippers since human
tissues are capable of metabolizing NMOR 151).

Summary

Persuasive evidence exists that the carcinogenic nitrosamines that
are present in high quantities in snuff and other forms of smokeless to
bacco are metabolized by target tissues of experimental animals and by
human tissues to intermediates that can modify the genetic material of
the cell.

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deoxyguanosine adduct upon reaction of N-nitroso-2-hydroxymorphe
line with deoxyguanosine. Carcinogenesis 6: 1671-1673,1985.
(51) Bartsch, H., Camus, A., and Malaveille, C. Comparative mutagenicity
  of N-nitrosamines in a semi-solid and in a liquid incubation system in
  the presence of rat liver tissue fractions. Mutat. Res. 37: 149-162, 1976.

EXPERIMENTAL STUDIES INVOLVING EXPOSING
LABORATORY ANIMALS TO SMOKELESS TOBACCO
OR ITS CONSTITUENTS

This section reviews bioassays evaluating the carcinogenicity in ani-
mals of smokeless tobacco and its constituents, particularly the
tobaccospecific nitrosamines (TSNA) described in the section on the
chemical constituents of smokeless tobacco. The bioassays involved
multiple routes of administration of chewing tobacco, snuff, or extracts
of these products and of several TSNA.

Studies of chewing tobacco, snuff, and TSNA are summarized in
tables 1 to 3 respectively, with comments on the individual investiga-
tions provided below.

Bioassays With Chewing Tobacco

Oral Administration

An alcohol extract of Indian chewing tobacco diluted 150 (group 1) or
1:25 (group 2) was gavagefed to male Swiss mice over 15 to 20 months.
In another group of mice, a mixture of the tobacco extract with stan-
dard laboratory diet was administered over 21 to 25 months (group 3).
This treatment produced tumors in 8 of 15 mice at risk in group 1, in-
cluding 5 mice with lung tumors and 2 with liver tumors; 4 of 10 mice at
risk in group 2 developed lung and liver tumors. The feeding experiment
(group 3) resulted in 8 of 10 mice with tumors, specifically 4 with tumors
of the lung and 4 with liver tumors. Despite the high toxicity of the
tobacco extracts and certain short-comings of the methodology, these
assays indicate that the extract of chewing tobacco is carcinogenic in
mice (1).

Application to the Oral Mucosa and Cheek Pouch

Three different extracts of an Indian chewing tobacco were applied
daily for up to 18 months to the buccal mucosa of strain A and Swiss
mice. No excess of tumors was observed (2). The oral mucosa of a group
of weanling Wistar rats was painted twice weekly with a 2-percent
alkaloid-free extract of an Indian chewing tobacco. No tumors were
observed at the application site even though applications were con-
tinued throughout the lifespan of the rats 13).

79


E  TABLE l.-Bioassays for Carcinogenic Activity of Chewing `lbbaceo or Chewing `lbbacco Extracts*



                                           Duration of       Fraction of Animals With `lbmors

    Route of     Species,                    Exposure
   Application    sex       `l&t Material and Dose     (Months)    EXpOSed               Controls     Reference

Oral-
intubation
Oral-feeding
Skin-
topical
Oral-
swabbing
Oral-
swabbing
Oral-pouch
implantation
Oral-pouch

Oral-pouch
swabbing
Oral-pouch
swabbing
Subcutaneous
injection

mice, M

mice, M
mice, M+F

mice, M+F

rats (NS)$

hamsters
UW
hamsters
(NS)
hamsters,
M
hamsters.
F
mice (NS)

extract diluted I:25         4/l/2
    diluted 1:50         15-20
0.2% extract in diet        21-25
DMSO extract (dose ?)       21-22

extracts applied daily,
dose not given
2% alkaloid-free extract,
dose not given- + time
2cm3 plug

up to 18

Lifespan

up to 30

DMSOextract three times
weekly
DMSOextract three times
weekly, dose not given
2% tobacco extract in water,
twice daily application
2% tobacco extract partially

18-24

5

6

IO-23

4110t lung adenocarcinoma
8115f and liver carcinoma
8llOt lung adenocarcinoma
0110
011
no excess tumors compared
to controls

o/10
0112

o/50

o/20


l/20

0110
0114

o/12

0112

3117

1117 squamouscell carcinoma

or completely free of alkaloids,
25 solution once a month

(site not specified)

o/7


0111


0110

o Abbmviskm: DMSO. dimethyl sulfoxide
t Animals at risk.
$ INS) = not stated.


TABLE 2.iBioassays for Carcinogenic Activity of Snuff or Snuff Extracts*

Route of
AoDlication

Species,
Sex

`ht Material
and Dose

              Duration of          Fraction of Animals With `hmors

           EXpOEUre                                       R&r-
Amdications        lMontbsl      EXDO!%Xl              Controls          ence

Oral-feedinz

Hamsters. M  S. 20% of diet       Once dailv         24         0/1OOt                Oil00            17

Lies-oaintinn

Mice. M

SE. dose not liven

3 times dailv

2          o/20                 0120             18

Oral-swabbing   Rats, M     SE+H         0.5 ml daily        2
               SE (approx. 30%)    0.5 ml daily       up to 30
               SE (approx. 30%)    0.5 ml daily       up to 30
                 + (NNN+NNK)
                  NNN+NNK      0.5 ml daily       up to 30

Lip canal-     Rats, F      S           200 mg twice daily    9-22
instillation              S           200 mg twice daily    18
                     H            200 mg           18
                    S+H          twice daily         18
Lip canal-      Rats. M     S            50 mg daily       up to 30
instillation

s+se
ES

50 mg daily
50 mn daily

up to 30
UP to 30

0120
o/30

5/30 (3 papilloma in oral
  cavity. 2 lung adenoma)
13/30 (8 papilloma in oral
  cavity, 5 lung adenoma)
1142t (oral carcinoma)
l/l0 (oral carcinoma)
017

217 (2 oral carcinoma)

0120             18
l/21 (lung adenoma)   20
l/21 (lung adenoma)   20

1121 (lung adenoma)

20

o/20
Oil0
0110
0110

21

22
22
22

3132 (papilloma and 1       Oil0             20
  carcinoma in test canal,
  1 oral papilloma)
1132 (oral papilloma)        Oil0             20
2121 (oral papilloma)        Oil0             20

Cheek pouch-    Hamsters                   10 ml paste once     up to 30      0150                 0150
instillation     lNS)S                    ?               6          0125              2:
                    H              ?               6          0125                                27
                    SfH            ?               6          11125 (papilloma and carcinoma                27

                                                   of the oral cavity)
Subcutaneous    Rats, M+F   SE              50 mg. 84 weekly     26          0182                 0182             28
injection                       applications
           Rats (NS)    TE              45 mg. 70 weekly     21 + 4       18175                 1175             29
                                  aoolications

   * Abbreviations: ES, extracted snuff; H. infected with herpes simplex virus; NNK. 4.(methylnitrosamino)-I-(-3.pyrldyl).I-butanone: NNN. N'-nitrosonornicotine. S. snuff. SE, snuff extract
   t NO tumors of the oral cavity, esophagus. nasopharynx and larynx; all other tumors nearly identical to those in control animals.
a3    $ INS) = not stated.


TABLE 3.-Csrcinogenicity of Tobacco-Specific Nitrosammes*

Nitrw  Species and
samine Strains

Route of   Principal
Application lhrget Organs Doee

NNN

NNK

NAT

NAB

NNA

A/J mouse
F344 rat

SpragueDawley rat
Syrian golden hamster

AIJ mouse         ip.
F344 rat              S.C.

Syrian golden hamster

S.C.

F344 rat

F344 rat
Syrian golden hamster

A!J mouse

i.p.
S.C.

p.0.

p-0.
S.C.

S.C.

p.0.
S.C.

i.p.

lung
nasal cavity
esophagus
esophagus
nasal cavity
nasal cavity
trachea
nasal cavity

lung
nasal cavity
lung, liver
trachea, lung,
nasal cavity

esophagus
none

none

0.12 mmollmouse
0.2-3.4 mmokat

1.0-3.6 mmokat

8.8 mmoUrat
0.9-2.1 mmol/harnster

0.12 mmol/mouse
0.1-2.8 mrnokat

0.9 mmolhamatm
0.005 mmol/hamst.er

0.2-2.8 mmoUrat

3-12 mmolkat
2 mmol/hamster

0.12 mmollmouse

' Hoffmann and Hecht (11)

A group of 12 male Syrian golden hamsters received topical applica-
tions on the buccaI mucosa of a dimethyl suboxide (DMSO) extract of
an Indian chewing tobacco three times weekly for 21 weeks. None of the
treated hamsters developed tumors in the oral mucosa; however, 8 of 12
treated animaIs had 1eukopIakia. These changes were not seen in the
oral mucosa of the animals treated with DMSO alone (4). In another
bioassay, 12 male hamsters received applications to the cheek pouch of
a DMSC extract of Indian chewing tobacco three times weekly over
their entire lifespan. Tumors were not observed in the treated group or
the control group (5). When 1 mg of a paste made of a chewing tobacco
extract was applied topicaky to the mucosa of the cheek pouches twice
daily over a 6-month period, and animals were maintained without fur-
ther treatment for another 6 months, the incidence of hyperplasia in the
buccaI pouches was 17.6 percent, that of dysplasia was 29.4 percent,
and that of squamous ceil papilloma or carcinoma was 17.6 percent in
17 hamsters. There were no tumors in the 20 control animaIs (6).
Fifty hamsters received implantations of a 2 cm3 plug of chewing
tobacco in their cheek pouches. The opening of the cheek pouch was
ligated and the animals were observed for 18 months. After 13 months,
21 of 50 animals had survived. No tumors were recorded upon termina-
tion of the assays (7).
Although the studies cited above had some inherent weaknesses due
to short application time or low dose, it appears, nevertheless, that both
the oral mucosa of rats and the cheek pouches of Syrian golden

82


hamsters are relatively resistant to the carcinogenic activity of the
extracts of chewing tobacco.

Subcutaneous Application

Seventeen C57 black mice were subcutaneously injected with 1 ml of
a 2-percent solution of either partly or completely alkaloid-free extracts
of an Indian chewing tobacco once a month for 1 to 24 months. One
squamous carcinoma at an unspecified site developed in one mouse
receiving the partly alkaloid-free extract (8).

Skin Application

A large number of studies have been published regarding the tumori-
genicity on mouse skin of various extracts of chewing tobacco. Most of
these bioassays failed to produce skin tumors. The negative results ap
pear to be due primarily to the low dose applied or the short duration of
the applications (9,101. The negative results indicate also that the con-
centrations of TSNA and PAH in these extracts do not suffice to induce
tumors upon topical application (11). However, the application of meth-
anol or DMSC extracts of cigarette tobacco induced a low but signifi-
cant number of benign tumors in the skin of CAFl and Swiss mice when
these extracts were applied three times weekly for up to 24 months to
the shaved backs of the mice (12,13). A number of studies have reported
tumor-promoting activity of the extracts of chewing tobacco when
these were applied to mouse epidermis previously treated with a tumor
initiator @&?,1416). The bioassay data with chewing tobacco are sum-
marized in table 1.

Bioassays With Snuff

Oral Administration

For 2 years, 50 male BIO 15.16 and 50 male BIO 87.20 hamsters were
each maintained on a standard diet containing 20 percent moist, fresh
snuff. Controls consisted of 50 male BIO 15.16 hamsters and 50 male
BIO 87.20 hamsters on a diet containing 20 percent cellulose (of caloric
value similar to the snuff-containing diet). The spectrum of tumors ob
served was nearly identical in both groups. Hamsters of both strains
gavaged 60 times with 5 mg of the carcinogen 3-methylcholanthrene
(MC) had a significantly increased incidence of both benign and malig-
nant tumors of the forestomach and large intestine. Hamsters of the
BIO 87.20 strain also had an increased incidence of stomach cancers
while the BIO 15.16 strain developed tumors of the skin. lo assay the
cocarcinogenic activity of snuff, 50 hamsters of each strain received the
diet containing 20 percent snuff plus 50 times 0.5 mg of MC. Compared
to the control group (diet containing 20 percent cellulose), the tumor
yield was not increased in the two experimental groups indicating a lack

83


of carcinogenic activity as well as of cocarcinogenic activity of the snuff
in this setting (17).

Application to the Lip, Oral Mucosa, or Cheek Pouch

The upper lips of 20 male BALB mice were painted 3 times a day for 5
days weekly over a 2-month period with a concentrated water extract of
snuff (group 1). In another group of 20 male mice, the upper lips were in-
oculated with herpes simplex virus type 1 (HSV-1) and were subse
quently painted with a concentrated snuff extract for 2 months (group 2).
A control group of 20 male mice received inoculation of the upper lips
with HSV-1 and painting with water (group 3). Wo months' exposure
to snuff extract (group 1) or HSV-1 inoculation (group 3) alone did not
induce dysplasia in the epithelium of the labial mucosa, while HSV-1 in-
oculation combined with painting of snuff extract produced epithelial
dysplasia and other histomorphologic changes (18).

In respect to this and other studies in which animals are infected with
herpes virus in addition to treatment with snuff extracts, it should be
noted that 20 to 40 percent of the U.S. population have periodic occur-
rences of labial herpes (19).

Male F344 rats were treated for up to 30 months by swabbing the oral
cavity with either a concentrated water extract of snuff (group 1; 13.2
vg NNN and 2.8 ug NNK per milliliter snuff extract solution), snuff ex-
tract enriched with the tobaccc~specific nitrosamines NNN and NNK
(group 2; 148 ug NNN and 30 ug NNK per milliliter snuff extract solu-
tion), NNN and NNK alone in concentrations corresponding to those
applied in group 2 (group 3; 135 pg NNN and 27.6 ug NNK per milliliter
test solution), or with water alone (group 4). Groups 1,2, and 3 consisted
of 30 male rats each and group 4 (control) of 21 rats. The incidence of
tumors in groups 1 and 2 was not significantly increased over that in
the control group. In the group of 30 rats treated with NNN and NNK
alone, 8 animals had oral tumors (6 papillomas in the cheek, 4
papillomas in the hard palate, and 1 papihoma of the tongue), and 4
animals had lung carcinoma. This study indicates that snuff contains
czucinogenic N-nitrosamines; however, when they are being tested in an
admixture with other components in the water extract of snuff, their
carcinogenic activity may be suppressed (20).

A group of 21 male and 21 female SpragueDawley rats were treated
with snuff placed in a surgically created canal in the lower lip. Approxi-
mately 0.2 g of a standard Swedish snuff (pH 8.3) was given twice daily
5 days per week for 9 to 22 months. The mean retention time of the snuff
in the canal was 6 hours, and the estimated daily dose was 1 g of snuff/kg
b.w. Using the same methodology, another group of 5 male and 5 female
rats was treated with alkaline snuff in the surgically created canal (pH
9.3). One of the 42 rats treated with regular snuff developed a squamous
carcinoma in the oral cavity after 8.5 months. The exposure to the regu-
lar snuff resulted in mild to moderate hyperplasia of the epithelium,

84


hyperorthokeratosis, and acanthosis. Among rats exposed to snuff for
18 to 22 months, 16 of 42 showed vacuolated cells penetrating deeper
into the epithelium with hyperplastic and atropic lesions. Rats exposed to
alkaline snuff differed little from those in the group treated with regular
snuff. Outside the area of treatment, squamous cell hyperplasia of the
forestomach was found in rats exposed to snuff for 18 to 22 months (21).
In another bioassay using the same methodology as described by
Hirsch and Johansson (21), the surgically created canal in the lower lip
of F344 rats was filled five times each week over 28 months with either
U.S. snuff (average 0.2 g per application; n=30), snuff enriched with its
own water extract (n=30), or the extracted residue of snuff (n=21). Ten
rats with the surgically created lip canal, and otherwise untreated served
as controls. The incidence of nonspontaneous tumors in each group was
the following rats treated with snuff had one squamous carcinoma of
the oral cavity, one squamous cell papilloma of the hard palate, and one
meningioma; treatment with enriched snuff led to one squamous cell
papilloma of the floor of the mouth and one nasal olfactory tumor; treat-
ment with extracted snuff induced one squamous cell papilloma of the
hard palate. There were no tumors in the control group (20).
Four groups of female SpragueDawley rats with surgically created
canals in the lower lip, received the following treatments beginning at 3
months of age: group 1 was infected with herpes simplex virus type 1
(HSV-1) by scarification and topical application followed 10 days later by
administration of snuff into the canal morning and night on 5 days per
week; group 2 was infected with virus and received no other treatment;
group 3 was sham-infected with sterile saline followed by snuff treat-
ment; and group 4, not given virus or snuff, served as controls, The
HSV-1 infection was repeated once after a l-month interval, and snuff
treatment was continued for 18 months after which time all animals were
killed. Three animals in each of groups 1 and 2 died from encephalitis
shortly after the second infection with HSV-1. Squamouscell carcinomas
of the oral cavity developed in two of seven rats, and a retroperitoneal
sarcoma was seen in one of seven rats exposed to HSV-1 plus snuff. In
the group exposed to snuff alone, 1 of 10 animals developed a squamous
carcinoma of the anus and 1 of 10 a retroperitoneal sarcoma (22).

In several studies, various forms of snuff were installed in the cheek
pouches of Syrian golden hamsters for up to 20 months. The application
of snuff did not lead to the induction of tumors in the cheek pouches nor
at any other site of the oral cavity in any of these studies even though
malignant tumors were induced in the oral cavity with high doses of 7,
12dimethylbenz(a) anthracene and 3-methylcholanthrene (z23-26).
In an assay for the joint action of HSV and snuff, the buccal pouches
of 125 Syrian hamsters were inoculated with HSV-1, HSV-2, or culture
medium. The control and HSV inoculations were done once a month for
6 consecutive months. Then 25 hamsters with HSV-inoculated pouches
received installations of commercial snuff twice daily into both the right

85


and left pouches. One month after the last HSV inoculation and 6
months after continuous snuff application, the assay was terminated.
The buccal pouches were removed for histopathologic examination.
Neither the application of snuff to the cheek pouches nor HSV infection
alone induced neoplastic changes in hamster buccal pouches. However,
HSV infection in combination with snuff resulted in epitheliaI dysplasia
and in squamous carcinoma of the buccal pouches in 11 out of 25 ham-
sters (27). This investigation provides the strongest evidence to date that
snuff may increase cancer risk in animals; however, full evaluation is pre
eluded since the findings have been published only in abstract form.

Subcutaueous Administration

A Swedish snuff was extracted with 6Opercent alcohol and resulted
in 18percent dry extract, which was injected subcutaneously into rats
with 7Opercent ethanol and tri-n-caprylin (1:ll as vehicle. The rats
received a total dose of 4.2 g of extract with 84 weekly doses of 50 mg of
extract. No tumors were observed at the area of injection (28). This
result is quite different from an earlier one by the same investigators in
which an alcohol extract from cigarette tobacco (20percent yield) was
injected into 75 rats with 70percent alcohol and glycerol as solvent
(1:3). Per week, 45 mg extracts were injected until the total dose
amounted to 3.2 g/rat. After 25 months, 18 of 75 rats had developed
malignant tumors, primarily sarcomas at the injection site (29). The
bioassay data with snuff are summarized in table 2.

Bioassays With Constituents of Smokeless Tobacco

At least three types of carcinogens occur in smokeless tobacco: poly-
nuclear aromatic hydrocarbons (PAH), polonium-210 (21oPo), and
N-nitrosamines. One of the PAH identified in smokeless tobacco,
benzo(a)pyrene (up to 72 ppb), has long been recognized as an animal
carcinogen (18,24,30). Levels of ZloPo in processed tobacco amount to
0.1-1.0 pCi per gram and to 0.18-1.22 pCi/g in commercial U.S. snuff
products. Ionizing radiation can cause multiple types of cancer in ani-
mals and humans raising the possibility that the alpha-radiation of
2loPo may contribute to the carcinogenic potential of smokeless
tobacco and especially snuff f31,31).
Three groups of N-nitrosamines have been identified in smokeless
tobacco. All of the 4 volatile nitrosamines thus far identified are carcino-
genic in animals (3). These are nitrosodimethylamine (0 to 215 ppb),
nitrosopyrrolidine (0 to 291 ppb), nitrosopiperidine (0 to 107 ppb), and ni-
trosomorpholine (0 to 690 ppb). Seven nonvolatile nitrosamines have also
been identified in smokeless tobacco. Of these, only nitrosodiethano
lamine (30 to 6,800 ppb) is a known carcinogen in mice, rats, and
hamsters (33) Swabbing of the oral cavity of 20 male and 20 female
hamsters with solutions of these agents three times weekly for 45 weeks

86


(20 mg per application) induced tumors of the nasal cavity in 17
animals, tumors of the trachea in 6, and a tumor of the larynx in 1 of the
hamsters (34).

The most abundant carcinogens in smokeless tobacco yet identified
are the tobaccospecific nitrosamines (TSNA). These are formed during
the processing of tobacco from its alkaloids. So far, seven TSNA have
been identified in smokeless tobacco. Of these, N `-nitrosonornicotine
(NNN; 470-135,000 ppb) and 4-(methylnitrosamino)-1-(3-pyridyl)-l-
butanone (NNK; 30-13,600 ppb) are powerful carcinogens in mice, rats,
and hamsters (table 1; 1,9). Table 3 summarizes results from bioassays
administering TSNA to test animals. A variety of tumors were produced,
particularly in the esophagus, nasal cavity, and lung. In a recently com-
pleted investigation, daily swabbing for up to 30 months of the oral
cavity of F344 rats with a saline solution containing 135 ppm NNN and
28 ppm NNK led to the development of benign oral tumors in 8 and
lung carcinoma in 4 of 30 rats. Neither oral tumors nor tumors of the
lung were observed in the negative control group (20). This study sug-
gests that NNN and NNK may be tumor&&c at the site of exposure
as well as systemically. Full evaluations of these results are precluded,
however, since the original manuscript is now under journal review and
not published.

It is noteworthy that some of the bioassays indicated that relatively
low doses of the TSNA could induce tumors. In hamsters, a total dose
of only 0.2 mmol/kg of NNK induced a significant incidence of tumors
(3s), whereas in F344 rats, 60 subcutaneous injections of a total dose of
20 mg (0.33 mmokkg) of NNK induced tumors of the liver in 10, tumors
of the lung in 13, and tumors of the nasal cavity in 6 of 30 rats. Subcu-
taneous applications to 27 rats of the same molar dose (0.33 mmokkg) of
nitrosodimethylamine resulted in 6 animals with tumors of the liver and
1 rat with a tumor of the nasal cavity (36). For NNN, high tumor inci-
dences were produced in F344 rats by a total dose of 1.0 mmovkg (37).
Based on daily use for 30 years of 10 g of snuff containing 3.1 ppm of
NNK, the estimated NNK exposure of a snuff dipper would be approxi-
mately 0.02 mmollkg. Exposure to NNN from the same brand would be
0.4 mmol/kg (figure 3, chapter 2). Hence, the bioassays indicate that
exposures in the dose range actually experienced by long-term snuff
dippers induce tumors in animals. This is a distinctive and potentially
important finding, since for most chemical carcinogens their carcino
genicity was detected following exposure at doses much higher than
usually received by humans.

Of the other five TSNA, besides NNN and NNK, N `nitrosoanabasine
(NAB; lo-6,700 ppb) and 4(methylnitrosamino)-1-(&pyridyl)-1-butanol
(NNAL; 140-300 ppb) were moderately active carcinogens, and N-nitro
soanatabine (NAT; 300-338,000 ppb) was inactive when tested at the
low dose level of 9 n-mol./kg (9,38).

87


Recently, two additional TSNA have been identified in snuff: 4
(methyhritrosamino)-4-(3.pyridyl)-1-butanone (1,300-1,800 ppb) and
4-(methyhritrosamino)-(3-pyridyl)butenel (10 ppb; 6). These two nitro
w-nines have not yet been tested for carcinogenicity.

Mutagenicity Assays and Other Short-Term Tests

Chewing Tobacco

Nicotinu rusticu is a tobacco variety that is widely cultivated and
used throughout India. Its ethanol extracts induced mutations in
Sahwn~lla typhimurium TA98 and in V79 cells of Chinese hamsters.
The addition of S9 liver homogenate from Aroclor-pretreated rats
enhanced the mutagenic effect. No mutations were induced in TAlOO,
TA1535, or TAX38 in the presence of the S9 homogenate. This ethanol
extract of tobacco also induced micronuclei in bone marrow cells of
Swiss mice (1,39,40).
An ethyl acetate extract of Indian chewing tobacco induced sister
chromatid exchange (SCE) in human lymphocytes and in a human
lymphoblastoid cell line. In the latter system, S9 rat liver homogenate
enhanced the effect. When the tobacco extract was tested in the absence
of the S9 homogenate it did not induce ouabain-resistance in Chinese
hamster V79 cells. The same extract, another ethyl acetate extract, and
an ethanol extract of tobacco induced cell transformation in Syrian
hamster embryo cells (41&f).
The incidence of micronucleated oral mucosa cells in 27 Indians using
khani chewing tobacco was 2.2 percent (0.8-4.9 percent). The incidence
of micronuclei in exfoliated cells of nonchewers of similar ethnic back-
grounds and dietary habits was 0.47 percent (0.0-0.9 percent) (43).

Snuff

The residue of organic solvent extracts from a U.S. commercial snuff
was dissolved in DMSO and tested for the induction of SCE's in human
peripheral lymphocytes. The organic snuff extract induced significant
SCE's with a 0.05 percent concentration in lymphocytes of one of three
donors, with a 0.15 percent concentration in lymphocytes in two of
three donors, and with a 0.5 percent concentration in lymphocytes of all
three donors (44).

Tobacco-Specific N-Nitrosammes (`I'SNA)

Of the seven TSNA so far identified in smokeless tobacco, only NNN
and NNK were also tested for genotoxicity in short-term tests. In the
presence of a liver microsomal preparation from Aroclor-induced rats,
NNN and NNK caused dose-dependent mutations in SuZmoneUu
typhimurium TAlOO and TA1535. Increased mutation frequencies were
observed in the case of NNN at 2.5 umol and at 5.65 timoUplate and in
the case of NNK at 1.4 wokplate (45-47).

88


NNN and NNK at 10-3 and 10-2 molar concentration each induced
unscheduled DNA synthesis in freshly isolated hepatocytes from adult
rats (48).

Summary

Chewing tobacco and extracts from various chewing tobaccos have
been tested by oral administration in mice, topical application to the
oral mucosa of mice, rats, and hamsters, and by subcutaneous adrnin-
istration and shin application to mice. The investigations failed to
demonstrate significantly increased tumor production. Short applica-
tion times and low-dose exposures, however, limit the evaluation of the
carcinogenicity of chewing tobacco or its extracts. Bioassays of snuff
have likewise generally shown no excess cancer, although some experi-
ments suggest that it may cause oral tumors in rats and hamsters that
are infected with herpes simplex virus. Among the chemical com-
ponents of snuff, the tobaccospecific nitrosamines NNN and NNK are
powerful carcinogens. The doses of NNN and NNK that produce
tumors in experimental animals are close to the doses estimated from
lifetime exposure among human snuff dippers.

References

(1) Shah, A.S., Sarode, A.V., and Bhide, S.V. Experimental studies on
mutagenic and carcinogenic effects of tobacco chewing. J. Cancer Res.
Clin. OncoL 109: 203-207,1985.

(2) Mody, J.K., and Ranadive, J.K. Biological study of tobacco in relation
to oral cancer. Ind. J. Med. Sci. 13: 1023-1037, 1959.
(3) Gothoskar, S.V., Sant, S.M., and Ranadive, K.J. Effect of tobacco and
Iime on oral mucosa of rats fed on vitamin B deficient diet. Int. J.
cancer 12 424-429,1975.

(4) Suri, K., Goldman, H.M., and Wells, H. Carcinogenic effect of a
dimethylsulphoxide extract of betel nut on the mucosa of the hamster
buccaI pouch. Nature 2%? 383-384, 1971.
(5) Ranadive, K.J., and Gothoskar, S.V. Betel quid chewing and oral cancer:
Experimental studies. In: H.E. Nieburgs ted.). Prevention and Detection
of Cancer, Part I, VoL 2. New York, Marcel Dekker, 1976, pp. 1745-1766.
(6) Rao, A.R. Modifying influences of betel quid ingredients on B(a)P-
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(71 Peacock, E.E., Jr., and Brawley, B.W. An evaluation of snuff and
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89


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(22) Hirsch, J.M.. Johansson, S.L., and Vahlne, A. Effect of snuff and
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(23) Dunham, L.J., and Herrold, K.M. Failure to produce tumors in the
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(24) Dunham L.J., Muir, C.S., and Hamner, J.E., III. Epithehal atypia in
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  J. Cancer 20: 588-593, 1966.

90


(2.5) Dunham, L. J ., Snell, K.C., and Stewart, H.L. Argyrophihc carcinoids in
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  507-513, 1975.

(2s Homburger, F. Mechanical irritation, polycyclic hydrocarbons, and
  snuff. Effects on facial skin, cheek pouch, and oral mucosa in Syrian
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(27) Park, N.H., Herbosa, E.G., and Sapp, J.P. Oral cancer induced in
hamsters with herpes simplex infection combined with simulated snuff-
dipping (Abstract 10). International Herpes Virus Workshop, Ann Ar-
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(28) Schm%hl. D. Priifung von Kautabakextract auf cancerogene Wirkung
  bei Batten. Anneimittel-Forsch. 15: 704-705, 1965.
(29) Dmckrey, H., S&m&I, D., Beuthner, H., and Muth, F. Vergleichende
  Priifung von Tabakrauch-Kondensatn, Benzopyren und Tabakextract
  auf carcinogene Wirkung bei Batten. Naturwissenschaften 47: 605-606,
  1960.

(30) Campbell, J.M., and Lindsey, A.J. PolycycIic aromatic hydrocarbons
  in snuff. Chem. Ind. London 951, July 6,1957.
(31) Harley, N.H., Cohen, B.S., and no, T.C. Polonium-210. A questionable
risk factor in smoking-related carcinogenesis. Banbury Report 3:
  93-104, 1980.

(32) Hoffmann, D., Harley, N.H., Fisenne, I., Adams, J.D., and
  Brunnemann, K.D. Carcinogenic agents in snuff. J. Natl. Cancer Inst.
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(33) International Agency for Cancer Research. Monograph on the evahra-
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  N-nitroso compounds. Lyon, France, International Agency for Cancer
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(34) Hoffmarm, D., Rivenson, A., Adams, J.D.. Juchatz, A., Vinchkoski. N..
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  cinogenicity of ZV-nitrosodiethanolamine in the Syrian golden hamster.
  Cancer Res. 4.X: 2521-2524, 1983.

(35) Hecht, S.S., Adams, J.D., Numoto, S., and Hoffmann, D. Induction of
  respiratory tract tumors in Syrian golden hamsters by a single dose of
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  smoke inhalation. Carcinogenesis 4: 1287-1290,1983.
(36) Hecht, S.S.. `B-u&in, N., Castonguay, A., and Rivenson. A. Compara-
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  Cancer R.-es. 46: 498-502.1986.

(37) Hoffmann, D., Rivenson, A., Amins, S., and Hecht, S.S. Dose-response
  study of the carcinogenicity of tobacco-specific N-nitrosamines in F344
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(38) Hoffmann, D., and Hecht, S.S. Perspectives in cancer research.
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  status and future directions. Cancer Res. 4.5: 935-944,1985.

91


fW Bhide, S.V., Shah, A.S., Nair, J., and Nagarajrow, D. Epidemiological
and experimental studies on tobacco related oral cancer in India. IARC
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f4OJ Sbimame, L.P., Monon, M.M., and Bhide, S.V. Mutagenicity of betel
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(41) Umezawa, K., Fujie, S., Sawamur, M., Matsushima, T., Koath, Y,
Tanaka M., and Takayama, S. Morphological transformation, sister
cbromatid exchange and mutagenicity assay of betel constituents. `Ibx-
  icol. Lett. 8: 17-22, 1981.

(421 Umezawa, K., `Ibkayama, S., Fujie, S., Matsushima, T., and Sugimura,
  T. In vitro transformation of hamster embryo cells by betel tobacco ex-
  tracts. !IbxicoL Lett. 2: 243-246,1978.

(4.3) Stich, H.F., Curtis, J.R., and Parida, B.B. Application of the micro-
nucleus test to exfoliated cells of high cancer risk groups: Tobacco
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(44) Tucker, J.D., and Ong, T. Induction of sister chromatic exchanges by
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145) Andrews, A.W., Thibault, L.H., and Lijinsky, W. The relationship be-
tween mutagenicity and carcinogenicity of some nitrosamines. Mutat.
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(46) Bartsch, H., MaIaveiIIe, C., Camus, A.M., Mart.&PIanche, G., Brun, G.,
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C., and Montesano, R. Validation and comparative studies on 180
chemicals with S. typhimurium and V79 Chinese hamster cells in the
presence of metabolizing systems. Mutat. Res. 76: l-50, 1980.
(47) Hecht, S.S., Lin, D., and Castonguay, A. Effects of alphadeuterium
substitution on the mutagenicity of 4-(metbylnitmsamino)-l-(3-pyridyl)-
  1-butanone. Carcinogenesis 4: 305-310, 1983.
(48) Williams, G.M., and Laspia, M.F. The detection of various nitre
samines in the hepatocyte primary culture/DNA repair test. Cancer
  L&t. 6: 199206, 1979.

CONCLUSIONS

1. The scientific evidence is strong that the use of smokeless toham
can cause cancer in humans. The association between smokeless
tobacco use and cancer is strongest for cancers of the oral cavity.
2. Oral cancer has heen shown to occur several times more fre
quently among snuff dippers than among nontobacco users, and
the excess risk of cancers of the cheek and gum may reach nearly
fiftyfold among long-term snuff users.

3. Some investigations suggest that the use of chewing tobacco also
may increase the risk of oral cancer.

92


4. Evidence for an association between smokeless tobacco use and
cancers outside of the oral cavity in humans is sparse. Some
investigations suggest that smokeless tobacco users may face in-
creased risks of tumors of the upper aerodigestive tract, but
results are currently inconclusive.
5. Experimental investigations have revealed potent carcinogens in
snuff and chewing tobacco. These include nitrosamines, poly-
cyclic aromatic hydrocarbons, and radiation-emitting polonium.
The tobacco-specific nitrosamines N-nitrosonornicotine and
4-(methylnitro samino)-1-(3-pyridyl)-1-butanone have been de
t.ect.ed in smokeless tobacco at levels 100 times higher than the
regulated levels of other nitrosamines found in bacon, beer, and
other foods. Animals exposed to these tobaccospecific nitro
samines, at levels approximating those thought to be accumu-
lated during a human lifetime by daily smokeless tobacco users,
have developed an excess of a variety of tumors. The nitro-
samines can be metabolized by target tissues to compounds that
can modify cellular genetic material.
6. Bioassays exposing animals to smokeless tobacco, however, have
generally shown little or no increased tumor production, although
some bioassays suggest that snuff may cause oral tumors when
tested in animals that are infected with herpes simplex virus.

RESEARCHNEEDS

It has been established beyond reasonable doubt that smokeless
tobacco use can in- the risk of cancer. The experimental and epi-
demiologic evidence is strongest for the association between oral cancer
and the chronic use of snuff. Additional studies are needed to determine
whether the patterns of risk differ according to the form of smokeless
tobacco, including reseamh evaluating cancer risks that are associati
with chewing tobacco and dry versus moist snuff, and to quantify fur-
ther the levels of risk in relation to differing levels of smokeless tobacco
expose.
The influence of smoking, alcohol, and other factors (including viral
expmues) on the smokeless tobaccoassociated risk of oral cancer also
should be explored further with an emphasis on detecting possible inter-
actions between these factors and smokeless tobacco.
Inhaled snuff may increase the risk of nasal carcinoma. The feasibil-
ity of initiating studies in areas where snuff sniffing is common should
be ascertained, and studies should be launched to confirm and quanti-
tate this possible relationship.
There have been few studies of smokeless tobacco and esophageal,
laryngeal, and gastric cancers. These investigations have provided
equivocal results, but in the aggregate, their findings raise the possibil-

93


ity of some increase in risk among smokeless tobacco users. Additional
case-control studies of these neoplasms should be encouraged. These
studies should be large enough to assess the risks that are associated
with smokeless tobacco use while controlling for the potential con-
founding effects of smoking, alcohol, and other risk factors.

Isolated reports have associated smokeless tobacco with cancers of
the cervix, pancreas, and other anatomic sites. Investigators with exist-
ing data from case-control studies of these neoplasms should be encour-
aged to perform analyses to determine whether associations with
smokeless tobacco exist. Similarly, existing data from cohort studies
with information on smokeless tobacco use should be analyzed. Reports
from two relatively large cohort studies have been published only as ab-
stracts. These should be expanded with detailed descriptions of both
the methods used and the findings for various cancers and should be up
dated to include followup into the 1980's. Recommendations for addi-
tional studies of the role, if any, of smokeless tobacco in the etiology of
cancers outside of the upper aerodigestive tract should await the results
of these analyses.
On the basis of current knowledge, it can be assumed that chewing
tobacco and snuff contain several unknown nitroso compounds that
may be contributors to the carcinogenic potential of these products. In-
depth analytical studies are needed for the identification of these
unknown compounds. Furthermore, mechanisms of their in vitro and
endogenous formation should be studied together with those of the ni-
troso compounds that are already known to occur in smokeless tobac-
cos. For the validation of the uptake of the major carcinogens by to
bacco chewers and snuff dippers, markers should be measured in the
target tissues and in physiological fluids. Major emphasis should be
placed on the identification and assays of DNA-adducts with tobacco
specific compounds in tissues of the oral cavity.
Finally, trends over time in agespecific oral cancer incidence and
mortality rates should be monitored to determine whether the increas-
ing use of smokeless tobacco by Americans is influencing national or
regional cancer patterns. Changes in the prevalence of use and in the
characteristics of smokeless tobacco products should also be docu-
mented. Such monitoring will provide a base upon which future investi-
gations of associations between smokeless tobacco and cancer can be
built.

94


Chapter 3.

  NONCANCEROUSAND
PRECANCEROUS ORAL HEALTH
EFFECTS ASSOCIATED WiTH
SMOKELESS TOBACCO USE


CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...99

The Effects of Smokeless Tobacco Use on
Oral LeukopIakia/MucosaI Pathology and the
%ansformation of Oral Soft Tissues ,107
Oral LeukopIakia/Mucosal Pathology . ,107
  %ansformationofOraISoftTissues.. . . ,113

The Effects of Smokeless Ibbacco Use on the
Gingiva, Periodontal Tissue, and salivary Glands  ........ ,123
Background and Definitions ...................... ,123
Gingival and Periodontal Tissue ................... .123
SalivaryGlands.. ............................ ..12 6

The Effects of Smokeless `Ibbacco Use on lb&h  .......... ,128
Background and Definitions ...................... ,128
  DentaICaries ................................ ..12 9
  OtherHardTissueEffects  ....................... ,130

C0ncIusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...130

ResearchNeeds....................................131

References.............. . . . . . . . . . . . . . . . . . . . . . . . . ..132

97


This chapter addresses the health effects of smokeless tobacco use on
the oral tissues through a systematic review of the relevant scientific
literature of animal and human studies. The major areas addressed are
the effects of smokeless tobacco use on the oral soft tissues, the
periodontium, and the teeth. This chapter also reviews information
regarding the potential of oral tissue altered by smokeless tobacco use
to transform to dysplasia and malignancy.
Within each area, except for the section on the transformation of oral
soft tissues, those tissues or conditions that are suspected to be most af-
fected by smokeless tobacco use, or that hold the greatest potential for
health effects, are considered initially. Where contradictory evidence
exists, these date are also presented. Studies that were judged to meet
stringent selection criteria* are presented first, followed by data from
less rigorous study designs and case reports.
Within the section on the transformation of oral soft tissues, the pre
sent&ion of the evidence is grouped according to clinical reports, cohort
studies, and case-control studies. This was done so as to be consistent
with the format used in the chapter on Csrcinogenesis Associated With
Smokeless `Ibbacco Use (chapter 2). In some cases, studies referenced in
this chapter are the same as those used in chapter 2. The reader should
review both chapters to obtain all pertinent information contained in
these studies.

Only studies from the United States and Scandinavia are included for
the sections on oral leukoplakia/mucosal pathology, gingival and perio
dontal tissues, and salivary glands. This assures that studies dealing
with similar types of smokeless tobacco are used for comparison pur-
poses. However, the section on the transformation of oral soft tissues
includes a fuller range of studies that have reviewed the histopathologic
changes associated with smokeless tobacc&nduced lesions. Studies in-
vestigating the histopathologic transformation of nonsmokeless
tobaccuinduced lesions have not been included.

A summary of selected studies that addresses study sample,
methods, and observations is provided in table 1 as a ready alphabetical
reference to the text. In addition, a summary of selected case reports is
provided in table 2. Emphasis has been placed on the issues of preva-
lence of oral tissue changes, types of changes, sitespecificity of
changes, and the effects of doseresponse.

o See Introduction. Overview. and Conclusions for discussion of criteria for causality

99


TABLE I.-Selected Study Summaries for the Noncancerous
      Oral Health Effects From the Use of Smokeless Tobacco

Study     Sample

Methods

Observations

cmnmenta

AxklL 1976

o 20,333 Swedes:   o ????????????*?o
51% females,    design.
49% males.     o Data collected
o Ages 15 years    on tobacco
and older.      habits,
            medications
           taken. oral
          hygiene status,
         and prosthetic
             status.

o ?o?*???o
examinations
utilized
diagnosis based
on specific
clinical criteria.

. Photographic
documentation
of all lesions
diagnosed as
leukoplakia or
lichen planus.

o Tissue speck-
n-lens taken of
selected ca3es.

o Statistical
analysis con-
ducted: t-tests,
chi square teats.
and. if appropri-
ate, Fisher's
exact test.

o Of 1,444 snuff
users, 116 (8%)
had "snuff dip
per's lesion"
(oral leuko
plakia).
o The prevalence
of oral
leukoplakia was
3.6% among the
total population
examimd

o It is not clear
how many of the
snuff users were
also tobacco
smokers.

o snuff dipper's
lesion implies
mumsal tissue
changeaatthe
site of snuff
placement.

Greer and
Paulson. 1983

o 1.119 teenagers
in grades 9-12.
o 117 110.5%)
smokeless
tobacco users:
113 males. 4
females.

o Denver.
Colorado.

o Cross-sectional
design.
o Questionnaire
administered to
determine years
of use, frequency
of use. brand of
tobacco used.
site of applica-
tion, use of other
confounding
agents, and
dental care
history.

LA?ukopl&i%
Mucosal
Pathology

o A suggested
association
between level
and duration of
smokeless
tobacco use and
mucosal lesions
(42.7% of smoke
less tobacco
users had oral
mucosal lesions).

o An analysis of
the influence of
cofactors was
not conducted.

o No statistical
analyses
reported.
. Examiners blind
to responses on
questionnaire.
o No comparisons
reported
between users of
smokeless
tobacco and
nonusers.

100


TABLE I.-Continued

Study

Sample

Methods

Observations

Comments

Grew and
Paulson. 1983
kont.)

o ?o?*???o
examination
conducted of
soft and hard
oral tissues.

o 26% of smoke
less tobacco
users had site
specific gingival
recession.

o Lesions graded   o Users with
according to a    lesions had
scale developed   longer use and
by Ax&ll et al.    higher daily
(1976) and mcdi-   exposure than
fied by Greer     users without
and Pouleon.     lesions.

Teeth

. `.  found no
evidence of
tobacco
associated
dental ties."

o No evidence of
occlusal or
in&al abrasion.

o OnecaseOf
cenical erosion.

o Smokeless
tobacco
associated
periodontal
degeneration
defined.

o Did not assess
the interrelation-
ship of smoke
less tobacco,
cigarettes, and
alcohol.

Greer et al..
1986

                    Salivary Glands
o 45 smokeless    o Cross-sectional   o Of 18 tissue
mbscco users    design               . Authors suggest
                    samples with
(43 males and 2                    that the degree

females); 15 sub-  o Lesions graded   salivary glands,   of salivary gland

jects in each    by classification   4 demonstrated   fibrosis. degan-
          developed by     sialadeuitis and
goup known as                     erative change,
             Grem and      degenerative     and sialadenitis
juvenih, young   Paulson. 1983.    Changes.      may be aas&
adulta. and                           ated with
geriat.liC.     o ?????*?? ?*o?   o A routine
                    pattern of      tobacco brand
. Ages 13.74      lesions classified
          according to     cllronic        instead of a

Y-.                    sialadenitis was   generaJizd
           scheme.               response awed
o ??*????                   not shown for

Colorado.     o Histomorpho    any of the three   by all tobacco.
          logical methods    age groups.
           used on tissue
          Specimens.    o Four patients
                   (age3 21. 25. 50
           * No statistical    and 66) showed
         analysis       either mild,
            conducted.      moderate, or
                    severs salivary
                   gland fibrosis.

101


TABLE l.-Continued

Study     Sample

Methods

Observations

Comments

Hirsch et al..
1982                          LWk0phkid
                                  MUcosal
                            Pathology
         o 50 male habitual  o Cross-sectional
        snuff dippers.             o Interpretation of o Dose considera-
                   design.       histomorphologi-   tions were made
        o 41.3.year mean  o Subjects       Cal and histo
                                chemical results   and confounding
         age hmge 15-84   classified on a                 variables con-

          Years).        four-degree scale   demonstrated     sidered.
                  of lesion severity   that the oral
         o ?????*?                               o Differences in
                 (developed by    mucosaf reaction
                   AxdI et al.,      to snuff-induced   brand of tobacco
                                              used were taken
                 1976); biopsies   hyperplasia in
                      were taken.      the basal cell     into account.

o Histomorpho    layers.
logical and his.  . Lethal damage
tochemical      was found in
methods con-    surface layers.
ducted on sub   o Duration of use
jects' tissue    and daily expo
snecimens.      sure to smoke

o Tobacco and
alcohol use
histories
ascertained from

a questionnaire.

less tobacco were
shown to affect
the severity of
the leukoplakia.
o Dysplasia could
not be predicted
by using sug
gested CIinical
degree of lesion
classification.

o Tissue speci.    o Statistical
mans from 74%   analysis con-
of patients     ducted: oneway
included salivary  analysis of vari-
glands.        ante and multi-
          ple comparisons
          using the
             Scheffe method.

Salivary Glands
o The salivary
glands and ex-
cretory ducts
showed degener-
ative changes of
a more severe
nature than
found in the sur-
face epithelium.
o 42% of salivary
glands demon-
strated siafaden-
itis and degsner-
ative changes.
o Weak oxidative
enzyme activi-

ties noted in
acinic cells in

salivary glands
with sialadenitis
and degenera-
tive changes.
o Some signs of
metabolic atypia
noted.
o Markedl degen-
erative c k nges
seen in salivary
glands associ-
ated with the
more severely,
clinicdy classi-
fied lesions.

o Degenerative
changes not spe-
cificdy defined
by authors.
o Authors state
that variations
in degenerative
changes of
salivary glands
may lx bemuse
of differences in
brands of snuff
and snuff-
dipping habits,

102


TABLE l.-Continued

Study

Sample

Methods

Observations

comments

Jungell and
Mahnstr6m.
1985

o 441 military
recruits.

o Ages 17-19
yf%X%
o Finland.

o 48 (11%) were
snuff users.
o l&9-year mean
age (range 17-2 1
years).

o Cross-sectional
design
o ???????**????
administered to
ascertain to
bacco product
use and drinking
habits and fre
quency of dental
care.

o ?o?*???o ?????*??
tion conducted.

o Biopsies taken of
21 snuff users
with lesions.

. Besting and
stimulated @ar-
affin served as
the stimulator)
salivary excre
tions measured.

o Statistical a&y-
sis conducted
t-test.

o 10 nonusers of
snuff also mea
sured for sali-
vary excretions.

salivary Glands

o Resting salivary
flow of snuff
users was signif-
icantly higher
than that of
nonusers.

o ?????o????
??o????? ?o??
was higher, but
not significantly,
among snuff
users than
among controls.
o There was no
difference in
buffering
capacity be
tween the two
groups.

o Authors inter-
pret difference in
resting salivary
flowtobea
reaction to the
presence of the
local irritant
snuff.

Modk et al..                       GighI and
1980                                 Period0ntal

o 232 school
ClIiIM 119
males, 113
females.

o 13.5 years mean
age.
o 11% of males
were regdsr
snuff users.

o Sweden.

o ????????????*?o
design.
o ?*?????????
about tobacco
product use his-
tory and oral
hygiene prac-
tices.
o ???*????????
dental indices
used t.0 measure
changes in oral
hygiene and
periodontal
conditions.
o Dental caries
assessed clini-
cally and radio
graphically.
o Statistical
analyses con-
ducted cross
tabulations, mul-
tiple regression,
and student's
t-test.

o TheUseOfSmlff
demonstrated a
significant
relation to gingi-
vitis after con-
trolling for
plaque.
o Effects of snuff
on the gingival
tissue included
both location of
the snuff and as
a predictor of
gingivitis in
general.

o Authors state
snuff use may
influence gingi
val tissue
directly result-
ing in gingivitis.

o Examiners blind
to reqmse3
from iuterview.

103


TABLE l.-Continued

Study      Sample

Methods

Observations

Comments

Offenbacher
and Weathers,
1985

o 565 m&s from
5 schools.
o 13.8.year mean
age (range lo-17
years).
o 75 (13.3%)
smokeless
tobacco users.
o ????????

L4?UkOjlhkid
MUcosal
Pathology

o Cross-sectional
design.      o Frequency of
            occurrence of

o Questio rmaire
used to obtain
history of tobac-
co product "se,
dental visits, and
social history.
o Intraoral exami-

soft
.g
ele\
!Pri
Eke vi

; tissue
hology was
aificantly
rated in users
gqJfgkF
  11 lesions).

nation conducted
using some stan-  o No attributable
dardized indices.   risk for mucosal

o Statistical anafy  pathology in
             smokeless
ses included: chi   tobacco users
square, odds     who were free of
~ZilkJJt&~, gingivitis.
        S
o Control group
Used.
          Giagival and
            PeriodOIltal
         o No relationship
             between smoke
            less tobacco use
          and the preva-
             lence of
          gingivitis.
           o Prevalence of
          gingival reces-
          sion signifi-
          cantly elevated
             in smokeless
            tobacco users.
            o A si fYnificant
             attrr "table risk
         exists for gingi-
            val recession m
            smokeless
            tobacco users.
             Teeth
           o Smokeless to
            bacco users with
          gingivitis had
           si,gnificantly

greater caries
arevalence corn

pared with non-
users without
gingivitis.
o Prevalence of
caries was signif-
icantly greater in
users wth gingi-
vitis who used
both snuff and
chewing tobacco
cornoared with
nonusers with
gingivitis or
those who were
gingivitis free.

o Soft tissue
pzs not
o Method of
selecting schools
for subject
ascertainment
not described.
o ??*???*??*?
variables
considered.

o Smokeless to
baCCOUSeis
viewed as a co
factor with the
presence of gin
givitis in pro-
moting gingivaf
recesskon.
o No dinhI defi.
nitions provided
for the assess-
ment of gingiti-
tis or gingival
recession.

104


TABLE I.--continued

Study     Sample

Methods

Observations

Comment43

Peacock et al.,
1960

o 1,338 employees
of local textile
miu.

o North Carolina.

o Cross-sectional
design
o ?*?????????
about tobacco
product use and
given an oral
examination.

Leukopw
MUcosal
Pathology

o Highly signifi-
cant relation-
ships between
chronic snuff
and tobacco use
and oral
leukoplakia
development
found for all age
groups and for
both sexes.

. Examiners blind
to interview
rmponma.
o 90% of
employees had
either poorly
fitting complete
dentures or only
few and rxrious
teeth

o Many employees
have had the
habit since they
were 3 years old.

Pot&on et al,
1984

o 445 subjects:
52% females,
47% males

. 56 (12.6%)
smokeless to
hacco "Sal3 (all
-W.

o 16.7-year mean
age Irange 14-19
Y-L
. Rurd Colorado.

o Cross-sectional
d@P.
o ???????**????
????*???????
(same as one
usedinGrmx
and Paulson.
1983).

o ?o?*???o ??????
nation conducted
oforalhardand
soft tissues.

o ?????*? ????
by classification
developed by
GWSIld
Poufson. 1963.

o Of 56 smokeless
t,htwco users, 35
(63%) had lesions
of the hard or
soft timues.

o 33 (58.9%)
smokeless tobac-
co users had mu-
cosal alterations.

o Mucod lesions
were found in
area of quid
placement.

o Duration of use
and length of
daily exposure
were factors in
the development
of lesions.

o Multiple lesions
in&same
subject reported

Giivd and
Paiodontal

o Of 56 smokeless
tobacco users. 15
(27%) had site
specific gingival
recession: 2 users
had periodontal
lesions only;
13 had both
mucosal lesions
and periodontal
destruction.

. Examiners blind
to responsea on
q"estionnaire.
o Definitions of
CIiuical states
provided.
o ????????*???
*??o???? *??
????????
o Ahistoryofcon-
folmdmg vari-
ables obtained.
Effects of
variables not
addressed
statisticauy

o Periodontal
degeneration
defined.

. Effects of con
founding vari-
ables not
addressed
statistically.

105


TABLE Z.-Summary of Selected Case Report&i

Study

      NUlUk         Product   Duration
country of users Age     Ueed     of use   Ffndings

Archard
E&r
1972

Chl-kte",
Amlstro"g,
and
McDaniel.
1979

Christen,
McDaniel.
and Doran,
1979

Frithiof
et al.. 1983

Hoge and
Kirkham.
1983

Pindborg
and
Poutson.
1962

Pindborg
and
Re".Wlp,
1963

Zitterbart.
Marlin, and
Christen,
1983

USA

USA

USA

USA

De-k

De-k

USA

3









1









14









21









1






7







12









1

31
42
60

S"Uff
Snuff
S"Uff

11 years
20 years
50 years

36     Snuff    13 years

18-22

Snuff,    6 months
chewing     to
tobacco    9 years

31-79

Snuff

1060 years 21121 with snuff-
       induced lesions local-
       idtoareawhere
      snuff was held; 2/21
       with observable
     gingival retraction.

20

S"Uff

lY-   Gingival recession and
    hyperkeratosis found
     where t.obam was
    habitually placed.

Not
reported

S"Uff

20-30 years 4/7 bad whitish
       mucous membrane
     with a delicately folded
      appearance at site of
     snuff placement.

3483

Snuff

20-50 years  12112 with mucous
       membrane that was
      "whitish, sometimes
      yellowish-brown, dry
      appearance with a very
      delicately folded or
      finely grooved
       surface."

36

Chewing
tobacco

24 years  Gingival recession,
      "smokeless tobacco
      users lesion," and
      abraded occlusal sur-
     faces of posterior teeth
      found where tobacco
     was habitually placed.

A homogeneous eosin-
opbilic submucoszd
deposit above the
"linor salivary glands
did not initiate a" in-
flammatoryrespo"=
nor support the possi-
bility that the deposits
were amyloid.

Gingival rcsession,
clinical leukoplakia,
period0"td bone loss,
and tooth abrasion
found where tobacco
was habitually placed.

8114 with clinically
detectable gin&al
recession; 9114 with
clinical leukoplakia;
11114 with erythema-
tou.9 soft tissue
changes where te
bacco or snuff was
habitually held.

106


THE EFFECTS OF SMOKELESS TOBACCO USE ON
ORAL LEUKOPLAKWMUCOSAL PATHOLOGY AND
THE TRANSFORMATION OF ORAL SOFT TISSUES

Oral LeukoplakiaMucosal Pathology

Background and Deftitions

Various oral soft tissue effects of smokeless tobacco use have been
relxxted in the literature. These effects include oral leukoplakia/mucosal
pathology. The actual terms used and the definitions employed to
describe these conditions vary widely from study to study (table 3). The
World Health Organization (WHO) defines oral leukoplakia as a white
patch or plaque that cannot be characterized clinically or pathologically
as any other disease (1). The mucosal pathology that is found in smoke
less tobacco users also has been referred to as hyperkeratosis, an oral
mucosal lesion that exhibits an abnormal whitish (keratinized) appear-
ance clinically. The authors' terms are employed when a specific study's
findings are described. However, in the discussion portion of the report,
the general terms of oral leukoplakialmucosal pathology are used.
The association between smokeless tobacco use and oral leukoplakia/
mucosal pathology has been moderately studied. The WHO has stated
that tobaux is an etiologic agent for the formation of oral leukoplakia (1).
This association was n&firmed at an International Seminar on Oral Leu-
koplalda and Associated Lesions Related to Tobacco Habits (21. In a re
view of the effects of tobacco habits other than smoking, the use of smoke
less tobacco/snuff was associated with the presence of leukoplakia (3).

Studies in the United States

Six studies have addressed the prevalence of oral leukoplakia/muco
sal pathology in smokeless tobacco/snuff users (49). In two of these
studies, blindness of the examiners toward the tobacco habits of the
subjects was maintained, and oral tissue findings in smokeless tobacco
users and nonusers were compared (7,9). Three of these studies investi-
gated adults (4@ and three investigated adolescents (7,9). In addition,
several case reports have described oral leukoplakialmucosal pathology
findings in smokeless tobacco users (1@13). Highlights of these studies
and reports are summarized below.

Offenbacher and Weathers investigated the oral tissue effects of
smokeless tobacco use in adolescent males from the greater metropoli-
tan area of Atlanta, Georgia (9). They used oral examinations and self-
administered questio maims on tobacco use. Of the 565 males who were
examined, 75 (13.3 percent) used smokeless tobacco. The difference in
the prevalence of mucosal pathology in smokeless tobacco users (22.7
percent) was statistically significant compared with that of nonusers
(4.7 percent); however, the authors did not provide specific diagnostic

107


TABLE 3.-Variations in Terms Used and Definitions Provided for
     LeukoplakiaMwoeal Pathology Associated With
     Smokeless Tobacco Use by Studies Cited

Study     Term(s) Used Definition(s) Provided

Comment.9

Ax6U 1976

Christ.S?n.
Armstrong,
and
McDaniel,
1979

christen,
McDaniel,
and Doran,
1979

Frithiof
et al., 1983

Greer and
Paulson.
1983

Hirsch,
Heyden, and
Thilander,
1982

Snuff-
dipper's
lesion.

Clinical
leukoplakia.

Leukoplakia.

Snuff-
induced
lesion.

Oral
mucosal
lesions
(alterations)
associated
with the use
of smokeless
tobacco.

Snuff-
induced
lesions.

A fourcategory classifi-
cation scheme based on
tissue color, wrinkhng.
and thickening was used.

"Implies only the clinical
feature of a white patch
or plaque on the oral
mucosa which will not
rub off and which cannot
be characterized clinically
or histologically as any
other specific disease."

"Implies only the clinical
feature of a white plaque
on themucosa.. .I'

"Tissue changes in the
oral mucosa" that are due
to snuff use.

These lesions were
defined by a modification
of a clinical grading
method developed by
Axdl et al. 1976.

These lesions were
defined by the grading
method developed by
Ax&l et al., 1976.

The authors believe that
this is a well-defined
irritation that excludes it
from the diagnosis of
leukoplakia.

The authors cite the
WHO 1978 and Waldron
and Shafer 1975
references (l&I

The authors cite the
Waldron and Shafer 1960
reference (48).

The authors cite the
WHO 1978 reference for
the definition of let&o
plakia and state that
"since the snuff-induced
lesion, with its typical
clinical pattern and its
specific etiology, obvi-
ously constitutes a
definite diagnostic entity,
the term `leukoplakia' is
avoided. I'

In addition, lesions were
classified by their
texture, contour, and
color.

-

108


TABLE 3.--contiuued

Study

lkrm(s) Used Definition(s) Provided

Comments

Hoge and
Kirkham,
1983

Moore,
Bissinger,
and ProehL
1952

Oral
leukoplakia.

Offenbacher  Mucosal
and      pathology,
Weathers,   soft tissue
1985     pathology.

Peacock,
Greenberg,
and Brawley,
1960

Pindborg
and Poulson,
1962

Pindborg
and
Renstrup,
1963

Poulson,
Lindenrnuth,
and Greer,
1984

Zitterbart,   Generalized
Marlin, and  smokeless
Christen,    tobacco
1983      users lesion.

Hyper-
keratotic-
appearing
tissue.

Leukoplakia.

Leukoplakia.

Snuff-
induced
leukoplakia.

Oral mucosal
lesions
(alterations)
associated
with the use
of smokeless
tdacco.

No definition is provided,
although the authors dis-
cuss the "formation of a
hyperkeratotic zone in
the region of the `snuff
pouch' where the tobacco
is habitually held."

No definition provided.

No definitions provided.

"A pearly white plaque on
the mucous membrane
which could not be scraped
off with a tongue blade."

No definition provided.

No definition provided.

The clinical appearance of
these lesions was defined
by a grading method
developed by Greer and
Poulson, 1983.

No definition provided.

The authors cite the
Shafer, Hine, and Levy
1969 reference 149).

The pathological findings
identified by the investi-
gators included morsica-
tio, ulcer, keratosisileuko
plakia, vesiculobullous,
petechiae, abscess,
erythema. mucocele, and
pericoronitis.

The investigators
described the mucous
membrane as having a
slightly whitish, deli-
cately folded appearance.

The investigators de
scribed the leukoplakias as
"slightly whitish, some
times yellowish-brown.
dry appearance with a
very delicately folded or
finely grooved surface."

Alterations in texture,
color, and contour of the
mucosal lesions also were
identified.

The lesion was described
clinically as "peculiarly
wrinkled and thickened."

109


criteria in this assessment. The range of mucosal pathologic findings in-
cluded such conditions as morsicatio (cheek biter's lesion), ulcer, kera-
tosisileukoplakia, vesiculobullous, petechiae, abscess, erythema,
mucocele, and pericoronitis. Although 50 percent of the smokeless
tobacco users with mucosal pathology had keratosisfleukoplakia com-
pared with 3.8 percent of the nonusers with mucosal pathology, the
authors did not identify the locations of the mucosal pathologies.

Peacock, Greenberg, and Brawley reported a significant relationship
between chronic tobacco use and the presence of oral leukoplakia* in a
study of 1,388 textile mill workers in North Carolina (5). The 362
employees who reported using smokeless tobacco had a significantly
higher prevalence of leukoplakia (34 percent) than did the 457 nonusers
(7.4 percent). In addition, the authors noted a direct leukoplakia and age
effect.

In a study conducted in Denver, Colorado, Greer and Poulson exam-
ined 1,119 teenagers in grades 9 to 12 to assess the relationship between
oral tissue alterations and the use of smokeless tobacco (7). Smokeless
tobacco was used by 117 (10.5 percent) of these teenagers. Of these, 42.7
percent had oral mucosal lesions? in the area of tobacco placement.
Forty-six percent of the teenagers with mucosal lesions also had con-
comitant periodontal tissue degeneration.$

Poulson, Lindenmuth, and Greer examined a sample of 445 teenagers
in five rural Colorado towns to assess the relationship betwen oral
tissue alterations and smokeless tobacco use (8). Smokeless tobacco was
used by 56 (12.6 percent) of the teenagers. Of these, 58.9 percent had
oral mucosal lesions in the area of habitual tobacco placement. Concom-
itant periodontal degeneration was noted in 39.4 percent of those with
oral mucosal lesions.

Contrasting the results of rural versus urban adolescent smokeless
tobacco users, Poulson, Lindenmuth, and Greer suggested that the
duration of use may be critical in the development of "oral lesions" (8j.s
Those adolescents with oral lesions used smokeless tobacco longer (an
average of 3.3 years in the rural and urban groups) than those without
lesions in both the rural and urban groups (2.3 years and 2.2 years,
respectively). In addition, the authors noted similar effects of different
levels of smokeless tobacco use in daily exposure. Users with oral le
sions were exposed 205 minutes per day in the rural group and 177
minutes per day in the urban group compared with users with no oral le
sions (110 minutes and 53 minutes, respectively). Also, more than twice

* Leukoplakia was defined as a "pearly white plaque on the mwous membrane nhlch could not be scraped off wth
a tongue blade.
t The authors used a mod~ficatmn of the classificatmn method that u'as developed by .&&I et al. that Identifies the
oral mucosal lesion> according to color. wrinkling. and thickening 1141.
$ The authors define this degeneratmn as "site-specific gm@val recession wth apical migration of the gingwa to
or beyond the cementwnamel ~unctmn. with OF wthout clmical evidence of inflammation."
$ The term "oral lesmn~' used here includes penodonral tissue degeneratmn and oral mucosal lesions.

110


as many marked oral mucosal lesions were identified in the rural
population as in the urban population.

Smith et al. examin ed a population of 15,500 snuff users by cytologi-
cal, histological, and visual means fs). Of these users, 1,751 (11.3 per-
cent) demonstrated oral mucous membrane changes. Although no defi-
nitions were provided, these changes were described as "cloudy or gray
glistening" areas having "wrinkled appearance(s)" and presenting
"white or red granular appearance(s)." The authors reported that when
snuff was withdrawn, the tissue returned to normal appearance.

Moore, Bissinger, and Proehl investigated the relationship between
tobacco use and oral cancer in male patients age 50 years and older who
attended the General lnmor Clinic in Minneapolis, Minnesota (4). The
authors noted that a significant number of the patients who manifested
oral leukoplakia (18 of 23-78.3 percent) used smokeless tobacco. A to
bacco user in this study was defined as a person who used the tobacco
product for 20 or more years. Apparently, some of these 23 patients
were also pipe, cigar, or cigarette smokers, although the exact number
was not specified. The authors indicated that the most severe patches of
leukoplakia were seen in patients who chewed "strong" tobacco and
over a longer duration (no quantification reported). In most instances in
which patients had stopped using smokeless tobacco, leukoplakia
disappeared.

Several case reports (table 2) have described oral leukoplakiaimucosal
pathology at the site of smokeless tobacco/snuff placement (1013).
These cases represent males of various ages with differing years of
smokeless tobacco/snuff use. Hoge and Kirkham reported that in one
patient, withdrawal of snuff resulted in a reversal of the hyperkeratotic
lesions (12).

Studies in Scandinavia

Studies of smokeless tobacco from Scandinavia have investigated the
prevalence of oral 1eukopWmucosal pathology in users (X-19).

Axell found 1,444 smokeless tobacco users (predominantly men) in
the 20,333 Swedes who were examin ed for soft tissue lesions (la. Of
these users, 116 (8 percent) had "snuff-dipper's lesion" (see table 3 for
definitions). The prevalence of oral leukoplakia among the total study
population was 3.6 percent.

Hirsch, Heyden, and Thilander f18) graded oral mucosal lesions on an
established four-point scale (14) and correlated these findings with the
snuff habits in 50 Swedes ages 15 to 84 years who used snuff routinely.
Younger patients were found to have lower degrees of pathologic
changes, while a significant predominance of older patients was noted
with higher degrees. The authors reported that patients with oral
mucosal lesions of the highest degree had used snuff an average of 34.7
years compared with the 9.2- to 13.6-year average for patients with
lower degrees of pathologic changes. They also noted that patients with
high degrees of pathologic changes dipped twice as long per day (an

111


average of 10.1 and 10.6 hours per day) as patients withlower degrees of
pathologic changes (5.2 and 6.5 hours per day, respectively). Although
these patients reported multiple tobacco habits, the authors stated that
no differences in clinical grading were found between patients who used
snuff only and those who used snuff and other tobacco products.

In addition, several case reports have described oral leukoplakial
mucosal pathology (table 2). In Sweden, Frithiof et al. examined 21
male snuff users ages 31 to 79 years (19). All had snuff-induced lesions
that were localized to the area in the oral cavity where the tobacco was
held. Similarly, leukoplakia lesions were found at the site of snuff place
ment in all 12 male users of snuff ages 39 to 83 years in a study in Den-
mark (15). In this latter study, 3 weeks after one of the patients discon-
tinued snuff use, the clinical appearance of the mucous membrane had
returned to normal. In another report, four of seven Danish male users
of snuff exhibited leukoplakia at the site of snuff placement (16).

Discussion

The studies from the United States and Scandinavia demonstrate
that oral leukoplakialmucosal pathology is associated with smokeless
tobacco/snuff use. In two studies, a higher prevalence of oral leuko
plakia/mucosal pathology was found in users compared with nonusers
of smokeless tobacco-22.7 percent compared with 4.7 percent (9) and
34.0 percent compared with 7.4 percent (5). In all of these studies, be
tween 8 and 59 percent of smokeless tobacco/snuff users were found to
have oral leukoplakialmucosal pathology.

It appears that the oral leukoplakialmucosal pathology noted in
smokeless tobacco/snuff users is found commonly at the habitual site of
tobacco/snuff placement. Using a similar grading classification for
snuff-induced lesions (7,14), all of the mucosal pathology that was noted
in four studies was at the site of habitual tobacco placement (7,8,17,18).
Similarly, the majority of the oral leukoplakia/mucosal pathology that
was described in the case reports was found where the tobacco/snuff
was usually placed.

The duration of use (in years) and daily exposure (in hours or minutes)
to smokeless tobacco appear to be critical in the development and sever-
ity of oral leukoplakiafmucosal pathology. Three studies using similar
approaches to the definition of oral 1eukoplakAmuco.A pathology and
to the measurement of exposure noted this effect (7,418).
Only two studies were designed to study the concomitant findings of
oral leukoplakia/mucosal pathology and other tissue changes. The
authors reported that 39.4 (8) and 46.0 (7) percent, respectively, of
smokeless tobacco users with oral leukoplakia/mucosal pathology also
had periodontal tissue degeneration (gingival recession). These oral soft
tissue changes also were found at the site of habitual tobacco placement.
In several studies where individuals had stopped smokeless tobacco
use, the oral leukoplakia/mucosal pathology disappeared (4,6,12,15).

112


Background and Defiitions

The previous section that discussed smokeless tobaccoinduced leu-
koplakia noted that clinically observable changes in soft tissue mor-
phology do occur as a result of smokeless tobacco use. Smokeless
tobaccoassociated lesions that have been traditionally classified as leu-
koplakias (white lesions) offer varying clinical degrees of differentiation
and may persist or progress with continued smokeless tobacco use.
Additionally, some leukoplakias have been observed to resolve clinically
upon the cessation of smokeless tobacco use. This section of the report
addresses the transformation of oral soft tissues. It discusses the poten-
tial for smokeless tobaccoinduced lesions to regress, persist, or continue
to progress to lesions with higher mahgnant potential or to malignancy.
There are varying clinical and histologic definitions in the scientific
literature related to tobaccoinduced changes (transformation) of oral
soft tissues. The following definitions represent those most frequently
encountered. It will be noted when significant variation of these defini-
tions occurs in studies cited:

o Oral leukoplakia-a white patch or plaque that cannot be charac-
terized clinically or pathologically as any other disease (1).

o Snuff dipper's leukoplakia-a leukoplakia associated with the use
of smokeless tobacco. These are further characterized as to differ-
ing morphologic forms.

o Erythroplakia-a lesion present as a bright red patch or plaque
that cannot be characterized clinically or pathologically as any
other condition, such as carcinoma or infection.
o FVecancerous condition-a generalized state that is associated
with an increased risk of cancer based on epidemiologic or histo
logic evidence.

o Precancerous lesion-a morphologically altered tissue in which
cancer is more likely to occur than in its apparently n0rma.l
counterpart.

o Acanthosis-an increased thickness of the spinous cell layer of the
epithelium.

o Hyperkeratosis-an increased thickness of the keratinized layer of
the epithelium.

o Hyperparakeratosis-an increased thickness of a normally para-
keratotic layer of the epithelium, i.e., surface cells with retained
nuclei.

o Hyperorthokeratosis-an incrased thickness of a normally kera-
totic layer of the epithelium, i.e., surface cells without retained
nuclei.

113


o Chevron keratinization-a keratinization pattern typified by verti-
cal streaks of parakeratinization that extend to the epitheliaI sur-
face and create surface irregularities by extensions of the outer sur-
face layer.

o Dysplasia-abnormal tissue development characterized by vary-
ing numbers and degrees of morphologic cell changes that reflect
grades of severity.

o Dysplastic changes include the following
- Pleomorphism in the size and shape of cells and their nuclei.
- Abnormal numbers of cells undergoing mitotic activity (discrep
  ancy in maturation).
- Atypical mitotic cells.
- Cytoplasmic atypicalities (altered nuclear to cytoplasmic ratio).
- Hyperchromasia.
- Irregular nuclear borders.
- Basal cell hyperplasia.
- Loss of polarity.

o Carcinoma in situ-a significant number of dysplastic epithelial
cdl changes that extend from the basal layer to the surface layer
without violation of the basement membrane.

o Verrucous carcinoma-a clinically verruciform cancer of epithelial
tissue that tends to be slowly and locally invasive with a metasta-
sis and mortality potential that is lower than classic squamous cell
carcinomas. The cells are well differentiated.

o Squamous cell carcinoma-a cancer of the stratified squamous epi-
thelium that has varying clinical appearances, is invasive, extends
beyond the basement membrane, and has a great potential for
metastasis.

Evidence of the relationship between smokeless tobacco use and the
transformation of oral soft tissues is represented by the following
  1. Clinical reports describing tobacco habits of persons with graded
   oral lesions.

2. Followup (cohort) studies of tissue changes, including trans-
formation to malignancy, among patients with leukoplakia.
3. Casecontrol studies or case series of oral cancer describing con-
comitant leukoplakia.

A review of the evidence in each of these study areas follows:

Clinical Reports of Oral Lesions in Association
With Smokeless Tobacco Use

Hirsch, Heyden, and Thilander (18) graded oral snuff-induced
mucosal lesions in 50 patients on a four-point scale according to criteria
developed by Ax&l (14):

114


o Degree 1: A superficial lesion with a color similar to the surround-
      ing mucosa, slight wrinkhng, and no obvious thickening.

o Degree 2: A superficial whitish or yellowish lesion with wrinkhng
      and no obvious thickening.

o Degree 3: A whitish-yellowish to brown lesion with wrinkhng,
      intervening furrows of normal mucosal color, and obvi-
       ous thickening.
o Degree 4: A marked whiteyellowish to brown lesion with heavy
       wrinkhng, intervening deep and reddened furrows, and
       heavy thickening.
Snuff habits and drinking habits of the patients were obtained from
questionnaires. Patients in the degree 4 category had been snuff dippers
significantly longer than the rest of the patients. Also, patients in de
grees 3 and 4 dipped approximately twice as long per day as did pa-
tients in degrees 1 and 2. The daily exposure to snuff was significantly
longer in degree 4 (10.6 hours) than in degrees 1 (5.2 hours) and 2 (6.5
hours). When total exposure was compared between the four clinical
groups taking into account hours of use per day as well as years of use,
significant differences were found.
In this study, no significant differences could be found with regard to
clinical grading and histologicai appearances between patients with
multiple habits (snuff, smoking, and drinking) and those who only used
snuff. The four clinical degrees of lesions exhibited an agedependent ef-
fect with younger patients usually found in clinical degrees 1,2, and 3
and a significant predo minance of older patients noted in degree 4.
Degree 4 lesions included an increased number of mitotic figures,
edema, and slight to moderate mflammation compared with the other
three degrees. Eighteen percent of the patients exhibited slight epithe
lial dysplasia, and lesions with slight epithelial dysplasia were found in
all categories. Patients in the dysplastic group had been snuff dippers
longer on average (23.9 years) as compared with those without dyspla-
sia (19.5 years). No case of moderate or severe dysplasia was noted. (The
authors referenced the WHO Collaborating Center for Oral Precancer-
ous Lesions as the definition for dysplasia (l).)
AxelI, M&n&ad, and Sundstrom obtained biopsies of the oral
mucosal lesions of 114 male dippers ages 20 to 88 years from a sample of
1,200 Swedish snuff dippers (14). Clinically, lesions were graded
(degrees 1 through 4) based on color and morphology. Lesions of higher
clinical degrees were associated with greater daily exposure to snuff in
terms of hours and grams of exposure. All but one of the biopsies
showed increased epithelial thickness. The outer layers appeared vacua
lated with occasional remnants of cell nuclei. Lesions in degrees 3 and 4
had more pronounced surface layers. Acanthosis was evident in all of
the clinical groups. None of the biopsies showed changes that were
interpreted as cellular atypia or epithelial dysplasia. The cessation of

115


snuff dipping for a few days was reported to result in clinical regression
of the lesions with loss of the vacuolated layer.
Greer et al. reviewed clinically and histologically examined smokeless
tobacc&nduced leukoplakias from 45 patients ages 13 to 74 years @O),
following criteria that were previously established by Greer and
Poulson (7/ as adapted from Ax&lL The vast majority of the mucosal
lesions were corrugated, white, and raised. No evaluations for an inter-
relationship between smokeless tobacco use, smoking, and alcohol use
and clinical or histologic tissue changea were attempted. Histologic
examinations for specific changes were reported. Dark celI keratino
cytes characterized by a strong affinity for basic dyes and by electron
density of their cytoplasm and nucleus and suggested as dedifferenti-
ated precursors of a neoplastic keratinocyte were found in 17 of 45 cases.
However, their presence was unrelated to the clinical degree of the lesion.
While they have also been observed in leukoplakias that are associated
with smoking (or other causes), the control group of nontobaccoinduced
hyperkeratoses demonstrated dark cell keratinocytes in only 3 of 45
rxses. Chevron keratinization of the epithelial layer representing altered
cellular maturation was present in 42 of 45 smoke+ tobaccoinduced
leukoplakias but in only 4 of 45 control leukoplakia cases. Koilocytotic
changea appearing as vacuolated epithelial cells that may obscure the
cytoplasm or appear with pyknotic nuclei, which are often associated
with inclusion of viral particles in epithelial cells, were present in 27 of 45
smokeless tobaccoinduced leukoplakias. In the entire sample of 45 cases,
only 1 case of dysplasia (described as occuing in a long-term smokeless
tobacco user) was identified Three of the following characteristics had to
be present for a lesion to be characterized as dysplastic:

o Loss of celIular polarity.
o Basal cell hyperplasia.
o Altered nuclearlcytoplasmic ratios.
o Anaplasia.
o Dyskeratosis.
o Atypical mitoses.

Because the dysplasia case also involved the use of alcohol and smok-
ing, it is not possible to attribute its appearance solely to smokeless
tobacco use.
In a study of 21 Finnish military recruits ages 17 to 21 years, mucosal
lesions corresponded to the site of snuff placement and included the
alveolar and labial mucosa to varying degrees (21). The duration and in-
tensity of snuff use for this specific group could not be determined from
the study. Epithelial hyperplasia and acanthosis were universally found
under the light microscope. Hyperorthokeratinization was noted in 12
cases, hyperparakeratinization in 9 cases, and Chevron-type keratiniza-

116


tion in 1 case. One case of mild epithelial dysplasia was noted that in-
cluded atypical and increased mitoses and loss of basal cell polarity. The
authors concluded that this suggests a positive relation between snuff
dipping and malignant changes.

Van Wyk biopsied 25 snuff-induced lesions from Bantu smokeless
tobacco users whose lesions had existed from a few weeks to 40 years
(22). Comparison biopsies were also taken from healthy parts of the
mucosa in the users, from healthy mucosa in nonusers, and from other
white lesions and squamous carcinomas. From the biopsies obtained
from snuff users, 18 cases of acanthosis, 23 cases of parakeratosis, 5
cases of keratosis, and 4 cases with numerous mitotic figures, plea
morphism, hyperchromatism, and an irregular basal cell layer were
noted. Additionally, 11 showed a disrupted appearance of the basement
membrane. Those not associated with inflammation were considered
possibly to be premalignant. Epithelium featuring these characteristics
has been referred to by some as "disquiet epithelium." Contrarily, the
author stated that "the impression is gained that no relationship exists
between oral malignancy and the use of snuff." This was based on the
widespread use of snuff but the occurrence of only one case of alveolar
or sulcular cancer (not in a snuff user) in the hospital during this study.

Several investigators have described connective tissue changes in
snuff-induced lesions. A hyalinized, eosinophilic material that occurs
well below the epithelium and around the minor salivary glands or in a
plane that is generally parallel to the epithelial surface has been
reported by Pindborg et al. (16), Archard et al. (23), Axell et al. (14), and
Greer et al. (20). The exact nature of and underlying explanation for the
finding are not clear. Additionally, the role of such a histologic finding
in the development or progression of premalignant or malignant lesions
has not been identified.

Cohort Studies

Several investigations have followed persons with oral lesions for
subsequent health outcomes. Smith reported the lo-year followup
results on a group of patients with smokeless tobacco-induced leuko
plakias (24). In the original study, oral cytologies were performed on
1,751 patients presenting with leukoplakias out of 15,500 snuff users
(6). Results of the oral cytology e xamination consistently indicated only
benign hyperkeratoses. * Biopsies were made of 157 leukoplakic lesions.
However, no objective criteria for lesions selected for biopsy were of-
fered. None of the biopsies showed changes consistent with dyskera-
tosis or malignancy. These patients were followed with repeat cytology
smears for 5.5 years. No additional significant mucosal changes were

* The use of oral c
of a high rate of fa E tology for detecring dysplastic changes in leukoplakic lesmns is less than satisfactory because
         e negative findmgs. The hy  rkeratinized nature of leuko lakic lesions renders them resistant
to the oral cytology scraping technique. CeUu r
missed m/.                  r changes in deeper layers o P the epithehum would thus likely be

117


reported. In a subsequent 4.5-year followup (10 years total followup),
periodic biopsies were done on 128 of the 157 patients who had originally
received biopsies (24). The authors reported no dyskeratosis or carci-
nomas in the followup study. The method of followup was not specified.
Significant numbers of patients were lost, and the clinicel and histologic
diagnostic criteria were not fully described.

A prospective study of oral cancer among persons with oral leuko
plakia or other possible precancerous lesions was conducted in the
Emakulum district, Kerala State, India, as part of a lo-year followup to
a much larger study of 50,915 adults in 5 rural districts of India (26).
Among those individuals who had been diagnosed as having a leuko
plakia during the original survey, there was a malignant transforma-
tion rate of 9.711,OOO per year for those who only chewed tobacco. For
those who both smoked and chewed, the rate was 5/1,000 per year, while
no malignancies were reported for individuals with or without tobacco
habits who had not had a previous oral lesion The transformation rates
among those with lesions were much higher than rates reported in the
United States or European studies. While these results are not directly
comparable to United States or European studies since the tobacco
chewed in India is a variable mixture of betel leaf, areca nut, slake lime,
and coarse tobacco, they suggest that the persons with leukoplakia are
at increased risk of oral cancer. Specific clinical morphotypes of
leukoplakia demonstrated varying potentials for malignant transfor-
mation: homogeneous, 2.27 percent; speckled, 21.4 percent; and ulcer-
ated, zero percent.

In a small study of English coal miners, 8 of 22 patients with leuko
plakia who chewed tobacco were followed for 5 years (27). Five of the
eight cases showed no advance in the lesions, and two showed regres-
sion. The author does not specify whether these were clinical or histo
logic determinations or whether the smokeless tobacco habit persisted
in all cases. One lesion that had been regarded as benign showed some
hyperorthokeratosis and acanthosis of the epithelium but with no more
than "minor epithelial atypia." The clinical appearance of this lesion
was reported to have regressed initially over an intermediate 2-year
period despite continuance of the habit of tobacco chewing and smok-
ing. Subsequent followup over a 2-year period indicated that the lesion
had progressed to an exophytic squamous cell carcinoma. The site of
the lesion was where the patient had held tobacco for 30 years. While
the malignant transformation rate in the group of chewing tobacco-
associated leukoplakias was 12.5 percent, the small numbers and high
dropout rate limit the significance of the finding. Of significance was
the unpredictable course of the malignant lesion, initially regressing
and then transforming into a squamous cell carcinoma.

In a Danish study, 32 patients with snuff-induced leukoplakias from
a group of 450 patients with leukoplakia were observed for a median
time of 4.1 years (28). Each patient had also used alcohol, with 17 per-

118


cent claiming daily use. Thirty-three biopsies demonstrated hyperplas-
tic epithelium with hyperparakeratosis in 87 percent of the cases; haIf
showed vacuolated cells. One initial case of epithelial dysplasia was
found, and one carcinoma was found to develop from a nondyskeratotic
leukoplakia over the followup period. This represents a rate of premalig-
nant or malignant transformation of 6.2 percent for either dysplasia or
carcinoma. In comparing the rate of development of dysplasia and car-
cinoma from snuff-induced leukoplakias to nonsnuff-induced leuko
plakias, the authors found no statistically significant differences. How-
ever, the rate of transformation in both groups was higher than would
be expected in individuals without leukoplakic mucosa.

In an earlier report on a small sample of 12 white male snuff-using
leukoplakia patients (use from 20 to 50 years), Pindborg and Renstrup
did not find any malignant transformation (15). Biopsies were taken
from sites where the snuff was held. All 12 showed unkeratinized hyper-
plasia of the epithelium with a few deep streaks of parakeratosis and
downgrowth and broadening of the rete pegs with the outer layers of
cells being vacuolated and large. The authors state that snuff-induced
leukoplakias are easily reversible. Based on the limited size of this sam-
ple, definitive conclusions could not be made.

Oral Lesions Concomitant With Oral Cancer

Thme hundred and thirty-three patients with cancers of the buccal cav-
ity and pharynx from the Robert Winship Memorial Clinic in Atlanta,
Georgia, were compared with three control groups: a group with dis-
eases of the mouth other than cancer or with no diseases; a group with
cancer of sites other than the mouth, pharynx, or larynx; and a group
without cancer and whose mouths were not examined-see chapter 2
(29). The authors, citing leukoplakia as a precancerous condition, found
leukoplakias "more commonly in women with low grade squamous car-
cinomas arising in the mouth and with multiple cancers. Snuff dipping
was frequently associated with leukoplakia and low grade cancer aris-
ing in the mouth."

In a case-control study in Minnesota of cancers of the alveolar ridge,
floor of the mouth, and buccal mucosa, it was noted that leukoplakias
and cancers of the mouth were related to the use of snuff or chewing to
bacco (4). The most severe leukoplakias were reported among those who
used "strong snuff" (no definition was provided) and held the quid at
the same site for many years. Patients who quit using smokeless to
bacco reportedly had leukoplakias disappear in most instances. A
number of patients had multiple primary carcinomas that were also
specific to the site of quid placement. Cancer lesions were described as
having developed slowly over a period of several years, although no
evidence of periodic clinical or histologic assessment was provided.

McGuirt reported on 76 oral cancer patients, most with carcinomas of
the alveolar ridge or buccal mucosa, identified from the tumor registry

119


at the North Carolina Baptist Hospital who had a documented history
of heavy smokeless tobacco use (30). Fifty-seven of these patients used
snuff and reported no cigarette, pipe smoking, or alcohol habits. The
range of use was from 10 to 75 years. Leukoplakias had previously been
excised in 13.9 percent of the cases, and 47 percent had associated
leukoplakias at the time of surgery. The author cited "panmucosal in-
sult" from smokeless tobacco use as the cause of multiple lesions and
recurrences-a type of field cancerization.

From histologic evaluations of oral tissue among 23 Swedish patients
with anterior oral vestibular cancer who were snuff users, leukoplakic
lesions were noted outside the snuff-associated tumor in 5 (31). Lake
plakia and multiple carcinomas occurred together with the snuff-
associated lesion in three cases. Eleven of nineteen cases assessed for
presence of candida were positive. The temporal relationship between
candida and carcinoma was not ascertainable, nor was the potential
etiologic role of candida.

Rosenfeld and Callaway examined data from records at Vanderbilt
University Hospital, Nashville General Hospital, and the office of
Rosenfeld for cases of squamous cell carcinoma arising in the mucous
membrane of the anterior twothirds of the tongue, the floor of the
mouth, the gingiva, and the buccal area (32). A total of 525 cases were
examined in users and nonusers of smokeless tobacco-300 occurred on
the gingiva and buccal areas. Among women with cancer of the buccal
or gingival area, 90 percent had a history of snuff use. While no periodic
quantitative or qualitative assessment of the natural history of the
cancers is provided, the authors do offer the following clinical impres-
sion of snuff-induced lesions in their study:

These carcinomas arising in the inner cheek and gingiva frequently
start as leukoplakia. Progressive thickening, cornification, and even-
tual cauliflower-like ulcerations ensue. All stages in the progressive
disease may be seen in microscopic sections from a mere slight in-
crease in the keratin layer, through carcinoma in situ to invasive
malignancy.

Twenty-five cases of histologically confirmed buccal gingival cancer
in female snuff users were identified at the University of Arkansas
Medical Center from 1950 to 1959 (33). Eleven cases occurred at buccal
sites, 10 gingival, and 4 buccal and gingival. The patients (ages 44 to
84 years-mean 67.5) had a smokeless tobacco habit between 20 and
50 years. The lesions corresponded to the site of habitual tobacco
placement. Leukoplakia was a concomitant lesion and had been pres-
ent for many years. Bepeat biopsies of lesions were made over long
periods in some of the patients. Leukoplakic lesions from other parts
of the mouth often showed atypia. An evolution from leukoplakia to
pseudoepitheliomatous hyperplasia to early squamous cell carcinoma
was found.

120


Di6cu6sion

In characterizing the role of smokeless tobacco use in the clinical and
histologic course of oral lesions, there are several problems. First, oral
leukoplakia should be considered a dynamic changing lesion of the oral
mucosa (34). Lesions retain the potential to resolve, remain static, or
progress depending on a variety of factors that may be either exoge
nous (e.g., smokeless tobacco use) or endogenous (e.g., natural tissue
defenses and repair potential). To achieve comparability of results
among investigators, a standard system for gauging epithelial
dysplasia is needed. Patients then could be followed prospectively to
quantify the incidence of dysplastic change, incidence of transforma-
tion from a dysplastic state to a cancerous state, or in some cases
transformation from an apparently benign to a cancerous state. But
ethical considerations do not ahow lesions to be monitored continuously
from benign states to moderate and severe dysplasias and carcinoma in
situ.

The next best alternative would be to provide estimates of risk for
malignant transformation based on empirical and clinical observations
or at least to quantify descriptively the association that smokeless
tobacco-induced lesions have with other lesions or other potential
etiologic factors. The body of literature on smokeless tobaccoinduced
lesions and their potential for malignant transformation allows for the
development of a conceptual model of the natural history of smokeless
tobacco-induced lesions (figure 1). This model is a composite of various
prospective, retrospective, cross-sectional, and case studies that relate
to smokeless tobacco-induced lesions, It depicts progressive changes
that may occur in some individuals who are habitual users of smokeless
tobacco and potential outcomes that could include death or disfigure-
ment for some individuals who use smokeless tobacco for several dec-
ades. The data are clear that habitual smokeless tobacco use can pro
duce mucosaI lesions (see leukoplakia discussion). It is also clear that
where groups of patients with smokeless tobaccoinduced leukoplakias
have been followed for several years, cases of cancer have been identi-
fied. Finally, when considering studies of oral cancers in habitual
smokeless tobacco users, there appears to be a consistent finding of
leukoplakias either having been previously excised in the area of habit-
ual tobacco placement or being found concurrently with and in proxim-
ity to oral cancers.

In comparing studies on the transformation potential of smokeless
tobacco-induced leukoplakias, it is found that different criteria have
been used by various investigators in defining dysplastic changes. The
number and nature of criteria that are considered and that are consid-
ered adequate to classify a case as dysplastic are not consistent. Addi-
tionally, the degree of agreement on diagnosis based on histology and
clinical history between individuals has been shown to be quite variable.
Pindborg, FLeibel, and Holmstrup tested the degree to which a group of

121


FIGURE 1.-A Conceptual Natural History of Oral Mucosal Changes
       Associated With the Use of Smokeless `Ibbacc~

Diagnostic                Oral Tissue
Level                    status

Smokeless Tobacco
Exposure Time

A                   HEALTH

CLINICAL

Leukcplaklas

Erythroplakias

Smokeless
Tobacco
Hablt

P-ooablllty Low

Probabmlit\/ High

D~sp~asx Changes

   I           t                t
CLINICAL and   De&h Powble         Deatr? Highly
HISTOLOGIC    01 Loss of Tissue         Powble or Potent'al
           and Function o         for Disfigurement *

I
Months
to
"ear

10+
Years

122


oral pathologists could agree on diagnoses where nine cases of epithelial
dysplasia, carcinoma in situ, or initial squamous cell carcinoma were
examined (35). Color photomicrographs and information on the topog-
raphy of the biopsy were presented. The authors' diagnoses were based
on the criteria that are described in the report from the WHO Interna-
tional Collaborating Center for Oral Precancerous Lesions (1). The
degree of agreement with the authors' diagnoses for the nine cases
ranged between 10 and 78 percent. This could partially explain the
range in prevalence and incidence of malignant transformation that is
reported by various investigators.

Other contributing factors in comparing studies could include differ-
ent population groups in terms of age and gender and other confound-
ing variables (e.g., smoking, alcohol use, and type of smokeless tobacco
product used). Each of these limitations is suggestive of the type of
research that is needed.

THE EFFECTS OF SMOKELESS TOBACCO USE ON THE
GINGIVA, PERIODONTAL TISSUE, AND
SALIVARY GLANDS

Background and Definitions
Reports of gingivitis, gingival recession, and degenerative salivary
gland changes associated with smokeless tobacco use are contained in
the literature. As with the previous section on oral leukoplakia, the
terms used and the definitions employed to describe gingivitis and
gingival recession vary widely from study to study. `lhble 4 displays the
variations found in the literature. As each study is described in the fol-
lowing narrative, the authors' terms are employed. However, in the
discussion portion of this report, the general terms of gingivitis and gin-
gival recession are used. General definitions for these terms and for
sialadenitis follow:

o Gingivitis-This condition refers to clinically detectable acute or
chronic mflammation, either local or general, of the gingiva.

o Gingival recession-In general, this condition describes the apical
migration of the gingiva with or without clinical evidence of
inflammation.

o Sialadenitis-Inflammation of the salivary glands.

Gingival and Periodontal Tissue

Studies that assess the relationship between smokeless tobacco use
and gingival and periodontal tissue effects are limited. The literature
consists of several cross-sectional studies in teenagers and a few case
reports.

123


TABLE 4.-Variations in `krms Used and Definitions Provided for
     Gingivitis and Gingival Recession by Studies Cited

Study

Term(s) used

Deftition(s) Provided Conunents

Christen,
Armstrong,

and -
McDaniel.
1979

Christen,
McDaniel,
and Doran.
1979

:OZYd
1983 '

Ho and
I(lr ham,
.f
1983

Mod&r.
Lavstedt,
and Ahlund,
1980

C$enbacher
Weathers,
1985

Paulson.
Lindenmuth,
and Greer,
1984

Zitterbart,
Marlin, and
Christen,
1983

Gingival recession,
periodontal gxket.
and loss of veolar
bone.

Clinically detectable
gingival recession.

Tobaccoassociated
periodontal
degeneration and
periodontal lesions.

Gingivai recession.

Gingivitisigingival
inflammation.

Gingivitis.
Gingival recession.

lbbacco-associated   "Defined as site
periodontal degener-
ation (other terms   specific gingival
include periodontal  recession with apical
          migration of the
deterioration," and
"localized periodon-  gingiva to or beyond
             the cementoenamel
tal degeneration    junction, with or
associated with the   without clinical
site of tobacco     evidence of
placement").       inflammation."

Gingivitis,
Gmgival recession.

No definition provided.
No definition provided.

No definitions
provided.

No definitions
provided.

Defined as site
specific gmgival
recession wrth apical
migration of the
gingiva to or beyond
the cementoenamel
junction, with or
without clinical
evidence of
inflammation."

No definition provided.

No definition provided.
No definition provided.

The tissue changes
were described in
zrofs by the

-

The authors defined
the recession as having
"exposed approxi-
mately 5 mm of labial
root surface" and
having destroyed the
"entire functioning
border of keratinized
gingiva."

-

-

The gingival recession
was "considered slight
to moderate, ranging in
l-4 mm apical migra-
tion when present."

-

-

The clinical findings
were described for each
tooth site involved.

124


Studies in the United States

Three cross-sectional studies have investigated the relationship of
gingival and periodontal tissue changes and smokeless tobacco use in
teenagers in the United States (7-9). Offenbacher and Weathers exam-
ined the effects of smokeless tobacco use on mucosal pathology, on the
presence of gingivitis and gingival recession, and on dental caries status
(discussed in next section) (9). Of the 75 smokeless tobacco users, the
authors noted 72 percent with gingivitis and 60 percent with gingival
recession. In those with gingival recession, 6.6 percent presented with
recession in direct juxtaposition to the location of the tobacco place
ment. The authors did not describe how many users of smokeless tobac-
co had demonstrated combinations of these oral conditions. Also, no
specific clinical definitions were given for the assessment of gingivitis
or gingival recession, although the latter findings were described as
"slight to moderate, ranging from 1 to 4 mm apical migration of gingi-
val tissue." The higher prevalence of gingival recession among smoke
less tobacco users (60 percent) as compared with that found in nonusers
(14.1 percent) was found to be statistically significant. There were no
statistically significant differences in gingivitis prevalence between
smokeless tobacco users (72 percent) and nonusers (77.1 percent).
Of 117 adolescent smokeless tobacco users in Denver, Colorado,
Greer and Poulson noted that 25.6 percent had tobaccoassociated
periodontal degeneration (7). As noted earlier, this condition was de
fined as "sitespecific gingival recession with apical migration of the
gingiva to or beyond the cementoenamel junction, with or without clini-
cal evidence of inflammation." Concomitant mucosal lesions were noted
in 76.6 percent of those who had periodontal degeneration (gingival
recession).

In a study of rural Colorado teenagers, Poulson, Lindenmuth, and
Greer (8) described 26.8 percent of 56 smokeless tobacco users with peri-
odontal degeneration (gingival recession) as defined by Greer and
Poulson (7). Eighty-seven percent of these had concomitant mucosal
lesions.

Several case reports (table 2) describe the occurrence of gingival reces-
sion and periodontal tissue destruction in individual smokeless tobacco/
snuff users (1@13). The patients in these case reports were males who
ranged in age from 18 to 36 years with varying duration of the smoke
less tobacco/snuff habit ranging from 1 to 24 years. Although not uni-
versally found, gingival recession was usually noted, and the majority
of patients presented with recession that was specific to the site where
the tobacco/snuff was habitually placed.

Periodontal bone loss at the site of snuff placement was described in
another patient who used snuff for 13 years (10). In one patient, 3 weeks
after cessation of snuff use, there was no regeneration of the lost gingi-
val tissue, although, as noted earlier, the hyperkeratotic areas had dis-
appeared (121

125


Studies in Sweden

Mod&r, Lavstedt, and Ahlund studied the oral health effects of
smoking and snuff use in 232 Swedish school children ages 13 to 14
years (119 boys and 113 girls) (36). Thirteen (11 percent) of the boys used
snuff. The children were interviewed regarding their tobacco and tooth-
brushing habits, and examin ers (blind to the interview results) clinically
assessed the degree of gingival mflammation, oral hygiene, and the
presence of calculus (discussed in the next section). Standardized in-
dices were used to assess all oral conditions. Controlling for the
presence of dental plaque, gingival inflamma tion was the only variable
that was significantly different between snuff users and nonusers.
Snuff use was directly correlated with the degree of gingival mflamma-
tion. The gingival inflammation noted was related to the site of smoke
less tobacco placement.

Discussion

The relationship of smokeless tobacco use and the health of gingival
and periodontal tissue has received minimal study. Because of the
variation in study designs and diagnostic criteria, comparisons between
available studies are inappropriate. Thus the effects of smokeless tobac-
co use on these tissues are not clearly understood.

With regard to gingivitis, one cross-sectional study noted no differ-
ence between users and nonusers (9). Another study, however, empha-
sized that there was a significant difference between users and nonusers
and that snuff use was directly correlated with the degree of gingival
inflammation (36).
Gingival recession is a common finding among users of smokeless
tobacco/snuff. In the U.S. cross-sectional studies, gingival recession
was found in 25.6 to 60 percent of teenage users (7-9). In the two Col-
orado studies, all the gingival recession was specific to the site of to
bacco placement (25.6 and 26.8 percent) (8). In the Georgia study, only
6.6 percent of the gingival recession was in the area of tobacco place
ment (9). In addition, several case reports have identified gingival reces-
sion at the site of habitual tobacco placement (1@13).
Between 76.6 and 86.6 percent of smokeless tobacco users who had
gingival recession also had concomitant mucosal pathology (7,s). These
soft tissue changes were found at the site of habitual tobacco placement.

Salivary Glands

Smokeless tobacco or its components may contribute to degenerative
changes and severe damage, such as undifferentiated carcinoma, to the
salivary glands and excretory ducts of humans and mice (1&20,2437). In
a study that assessed the formation of tobacco-specific nitrosamines
from the major tobacco alkaloid nicotine, Hecht et al., reporting from the
histologic evaluation, noted two undifferentiated carcinomas of the

126


salivary glands in two groups of mice that were given injections of
nitrosonomicotine (NNN) in saline or trioctanoin (37). Because of the
uncommonness of salivary tumors in strain A mice, Hecht et al. con-
cluded that the tumors were probably a result of systemic administra-
tion of NNN.

SiaIadenitis and degenerative changes in minor salivary glands were
found in 16 of 50 habitual snuff dippers with a greater number belong-
ing to the groups that were classified clinically as having the most
severe snuff-induced lesions (18) (table 1). The findings from this study
included a decrease in oxidative enzyme activities and indications of
metabolic aty-pia that were based on enzyme histochemical tests. The
salivary glands appeared to manifest more damage than the oral epi-
thelium from snuff use. Variations in degrees of effect may be attrib
uted to the variations in snuff dipping habits and brands of snuff.

In a recent study by Greer and his colleagues (20) (table l), 45 smoke
less tobacco users ages 13 to 74 years were clinically and histomorpho
logically assessed for the effects of smokeless tobacco on the oral
tissues. Of 45 tissue specimens, 18 included salivary gland tissue.
Damage in the form of sialadenitis and other degenerative changes in
salivary glands was shown in 4 of the 18 specimens. A consistent pat-
tern for chronic sialadenitis was not found among any of the age groups.
The authors did not specify the other degenerative changes. However,
four patients, ages 21,25,50, and 60 years, demonstrated either a mild,
moderate, or severe salivary gland fibrosis. The most severe salivary
gland fibrosis was found in the 21-year-old subject who was considered
a short-term smokeless tobacco user; a definition for short-term user
was not provided. Unlike the findings of Hirsch, Heyden, and ThiIander
(18), salivary gland fibrosis or changes were not related to the stage
(degree) of the clinical lesion. The authors concluded that there is no
doubt that salivary gland fibrosis can be shown and that it is likely to be
related to the damage from smokeless tobacco. They also commented
that "It is likely that the degree of salivary gland fibrosis and degenera-
tive change, along with sialadenitis, may be a factor that is associated
with tobacco brand rather than with a generalized reaction caused by alI
tobam. ' '

Included among the many questions concerning the effects of smoke
less tobacco use on the salivary glands is that of changes on the flow
and buffering capacity of saliva. In a sample of 48 Finnish snuff users
ages 17 to 21 years (mean 18.9), the resting and stimulated salivary flow
was measured (21) (table 1). The subjects refrained from the use of snuff
for 1 hour before collection of saliva. The saliva of 10 nonusers was
simiIarly collected. The statistically significant findings demonstrated
a higher resting salivary flow of snuff users compared with controls.
Although the stimulated salivary flow was also higher among the snuff
users than the controls, this difference was not statistically significant.
Buffering capacity was the same between the two groups. Although

127


these findings offer additional information regarding the effects of
smokeless tobacco on the salivary glands, the clinical significance of
these effects has not been systematically assessed, nor have the out-
come differences related to the different products. Replication studies
of these findings are needed before firm conclusions can be made.

In contrast to the effects just cited, Archard et al. were unable to
identify lesions or dysfunctions associated with smokeless tobacco use
(23) (table 2). These investigators carried out histochemical tests on le
sions in the oral cavity that were in close proximity to the salivary
glands. These tests revealed no evidence of an mflammatory reaction
associated with the glands.

The interpretation of data within this general area requires caution.
Limited evidence suggests a possible relationship between the use of
snuff and damage to the salivary glands. Should this be the case, the
loss of salivary gland function can result in the decreased production of
saliva and the ultimate loss of a protective buffer for the oral epithelium
and the teeth against numerous exogenous factors such as infectious
agents, including dental caries.

THE EFFECTS OF SMOKELESS TOBACCO USE ON TEETH

Background and Definitions

This section of the chapter addresses the role of various forms of
smokeless tobacco in causing or contributing to diseases or conditions
of the teeth. Specific effects that are examined include dental caries,
abrasion, erosion, plaque and calculus buildup, and staining. For pur-
poses of discussion, definitions are offered for a number of terms that
are considered to represent commonly held concepts of diseases and
conditions of the teeth as evidenced in the relevant scientific literature.
o Dental caries-Clinically detectable cavitation of the coronal or
root surfaces of the tooth that is caused by acid demineralization of
colonizing bacteria on tooth surfaces.

o Abrasion-Clinically evident wear of the coronal portion of teeth
either generally or focally that appears excessive for a patient of a
given age. This is a mechanical effect that is caused by the action of
abrasive substances or objects during normal functioning or by
oral habits.

o Erosion-Loss of tooth structure that is attributable to a chemical
agent.

o Plaque-Bacterial-laden, proteinaceous material that is continu-
ally deposited in the oral cavity through the proliferation of bac-
terial types.

128


o Calculus-A concretion that forms on the coronal and exposed root
surfaces of teeth through the calcification of bacterial plaques.

o Staining-An extrinsic stain deposit that results in discoloration
on tooth surfaces.

Dental Caries

Evidence for the effects of smokeless tobacco use on the teeth is avail-
able from several cross-sectional studies (table l), from a limited number
of case reports (table 2), and from a limited number of related investiga-
tions of the potential for constituents of smokeless tobacco to serve as
predisposing or etiologic factors in the development of dental caries.
As previously mentioned, Offenbacher and Weathers reported on the
oral soft and hard tissue effects of smokeless tobacco use in a study
population that comprised 565 males with a mean age of 13.8 years (9).
This population typifies the age group that is commonly described as
"the cavity-prone years." Although caries rates expressed as decayed,
missing, or filled teeth (DMFT) were higher for smokeless tobacco users
without gingivitis than for nonusers without gingivitis, these differ-
ences were not statistically significant. However, when DMFI' scores
for smokeless tobacco users with gingivitis were compared with scores
for nonusers without gingivitis, a significantly higher caries prevalence
was found among users. Among students who used both snuff and
chewing tobacco, the DMFT score was 6.56 + 0.71. This score is
significantly elevated compared with scores of nonuser gingivitis-free
students and the nonuser group that had gingivitis. There was a
2.4-fold increase in disease experience. In this study, the presence of
gingivitis was presented as a cofactor with smokeless tobacco use in the
increased prevalence of dental caries. This finding has not bean reported
elsewhere, and the biologic explanation is unclear.
The different that were noted in caries rates could not be accounted
for based upon differences in oral hygiene or the frequency of dental
visits-two factors that could potentially affect DMFT scores. The ex-
aminers had no knowledge from the self-reported survey forms of the
history of smokeless tobacco use among the group that was examined;
thus, a degree of study "blindness" was attained. Absolute blindness in
these types of surveys is difficult because it is likely that some evidence
of smokeless tobacco use (e.g., tobacco residues, stain, odor, and soft tis-
sue effects) is observable. No quantifiable doseresponse effect for
smokeless tobacco use and dental caries was reported in this study.
Dental caries is highly age dependent, and no age adjustment was made
in the statistical analysis.
A cross-sectional study by Greer and Poulson of 1,119 teenage
smokeless tobacco users and nonusers from urban Colorado demon-
strated neither "tobaccoassociated dental caries" nor occlusal or in-
cisal abrasion of the teeth (7). This finding is not surprising because

129


abrasive effects are cumulative and would likely require a number of
years to become evident. The abrasion that has been reported in smoke
less tobacco users has been in adults who have used smokeless tobacco
products, generally leaf and plug forms of tobacco, for years (10,13). The
Greer and Poulson study reported a single case of cervical erosion on
the mandibular central incisors.

Some case reports have implied a causative role for smokeless tobac-
co in the development of dental caries (38,39), while others have postu-
lated a potential protective effect from caries (13,40). The presumed
mode of protection would be through a greatly increased salivary flow
that may provide a buffering action. Additionally, there is evidence that
various forms of smokeless tobacco contain fluoride, from a few tenths
to several parts per million, which may offer some cariostatic protection
(41). At the same time, various types of smokeless tobacco contain up to
five different forms of caries-promoting sugars (42). Rvo studies
reported that constituents in smokeless tobacco products either cause a
proliferation of caries-producing bacteria in vitro or, at the least, do not
inhibit bacterial growth in vitro (43,44). The fluoride and sugar contents
of smokeless tobacco vary by product type (41). This may explain the in-
consistent and equivocal results obtained by different investigators.
Variations in reported caries rates, if truly reflective of the larger
population of smokeless tobacco users, may represent the clinical out-
come of a number of antagonistic or synergistic factors that operate
while smokeless tobacco is used.

Other Hard Tissue Effects

Plaque, calculus, and staining are extrinsic factors that may be asso
&ted with smokeless tobacco use. This is clinically important because
dental plaque and calculus that is coated with plaque harbor bacteria
that can produce acids and toxins and thus bring about dental caries
and diseases of the periodontal structures. The stainfng of teeth, restor-
ations, and prosthetic appliances have been described as resulting from
smokeless tobacco use (13,22,45,46). Van Wyk also reported a constant
finding of chronic mflammation of tooth pulps that were extracted from
oral snuff users (22). He attributed this as being "probably due to the
irritation of the snuff overlying the exposed dentine and cementum."
No quantifiable evidence currently documents the risk of smokeless
tobacco use compared with nonuse in the development of plaque, calcu-
lus, or staining or the relationship of staining to oral disease conditions.

CONCLUSIONS

1. Smokeless tobacco use is responsible for the development of a
portion of oral leukoplakias in both teenage and adult users. The
degree to which the use of smokeless tobacco affects the oral hard

130


and soft tissues is variable depending on the site of action, type of
smokeless tobacco product used, frequency and duration of use,
predisposing factors, cofactors (such as smoking or concomitant
gingival disease), and other factors not yet determined.
2. Dose response effects have been noted by a number of investiga-
tors. Longer use of smokeless tobacco results in a higher preva-
lence of leukoplakic lesions. Oral leukoplakias are commonly
found at the site of tobacco placement.

3. Some snuff-induced oral leukoplakic lesions have been noted
upon continued smokeless tobacco use to undergo transforma-
tion to a dysplastic state. A portion of these dysplastic lesions
can further develop into carcinomas of either a verrucous or
squamous cell variety.

4. Recent studies of the effects of smokeless tobacco use on gingival
and periodontal tissues have resulted in equivocal findings. While
gingival recession is a common outcome from use, gingivitis may
or may not occur. Because longitudinal data are not available, the
role of smokeless tobacco in the development and progression of
gingivitis or periodontitis has not been confirmed.

5. Evidence concerning the effects of smokeless tobacco use on the
salivary glands is inconclusive.

6. Negative health effects on the teeth from smokeless tobacco use
are suspected but unconfirmed. Present evidence, albeit sparse,
suggests that the combination of smokeless tobacco use in individ-
uals with existing gingivitis may increase the prevalence of dental
caries compared with nonusers without concomitant gingivitis.
F&ports of tooth abrasion or staining have not been substantiated
through controlled studies; only case reports are available.

RESEARCHNEEDS

The review of the literature for this component of the report has iden-
tified the need for research in each of the areas discussed: the oral soft
tissues, the periodontium, the salivary glands, and the teeth. Basically,
the effects of the various types and forms of smokeless tobacco in all
age groups should be investigated. Controlled studies and comparisons
between users and nonusers of smokeless tobacco are needed. Estab
lished criteria for assessing tissue changes and disease presence should
be applied to permit comparability between studies.

Studies should include the identification and control of variables that
also may affect these tissues. Such variables may include alcohol use,
diet, oral hygiene practices, microbial flora changes, and salivary flow
rate, composition, and pH. In addition to these variables, consideration
should be given to the effects of concurrent disease states. For example,

131


the effects of smokeless tobacco on dental caries in the presence or
absence of gingivitis should be investigated.

The natural history of smokeless tobacc&nduced lesions resulting
from continued, intermittent, and discontinued smokeless tobacco use
needs investigation. Histopathologic evaluations and clinical examina-
tions to determine the natural history of oral leukoplakia/mucosal
pathology and salivary gland pathology are desirable to understand
completely the extent and severity of smokeless tobacco oral effects.

In general, incidence and prevalence studies should be implemented,
Prospective study designs should be pursued to dssess the temporal
relationship between smokeless tobacco use and various health effects.
In addition, dose-response studies are needed to assess dose in terms of
both duration of use (in months and years) and daily exposure (in
minutes and hours).

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(2) A&II, T., Hohnstrup, P., Kramer, I.R.H., Pindborg, J.J., and Shear, M.
International Seminar on Oral Leukoplakia and Associated Lesions
Related to Tobacco Habits. Community Dent. Oral Epidemiol. 12:
145154, 1984.
(3) International Agency for Research on Cancer. Tobacco habits other than
smoking Bet&quid and areca-nut chewing and some related nitro
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(4) Moore, G.E., Bissinger, L.L., and ProehI, E.C. Tobacco and intraoral
cancer. Surg. Forum 3: 685688, 1952.
(5) Peacock, E.E., Jr., et al. The effect of snuff and tobacco on the produc-
tion of oral carcinoma: An experimental and epidemiological study.
Ann. Surg. 151: 542-549, 1960.

(6) Smith, J.F., Mincer, H.A., Hopkins, K.P., and Bell, J. Snuff-dipper's
lesion. A cytological and pathological study in a large population. Arch.
Otokuyngol. 92: 450-456, 1970.

(7) Greer, R.O., Jr., and PouIson, T.C. Oral tissue alterations associated with
the use of smokeless tobacco by teenagers. Oral Surg. 56: 275~284,1983.
(8) Poulson, T.C.. Lindenmuth, J.E., and Greer, R.O., Jr. A comparison of
the use of smokeless tobacco in rural and urban teenagers. CA 34:
248-261, 1984.

(9) Offenbacher. S., and Weathers, D.R. Effects of smokeless tobacco on
the periodontal, mucosal and caries status of adolescent males. J. Oral
Pathol. 14: 169-181. 1985.

(10) Christen, A.G., Armstrong, W.R., and McDaniel, R.K. Intraoral
  leukoplakia, abrasion, periodontal breakdown, and tooth loss in a snuff
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(11) Christen, A.G., McDaniel, R.K., and Doran. J.E. Snuff dipping and
  tobacco chewing in a group of Texas college athletes. Tex. Dent. J. 97:
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(12) Hog-e, H.W., and Kirkham, D.B. Clinical management and soft tissue
reconstruction of periodontal damage resulting from habitual use of
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(13) Zitterbart, P.A.. Marlin, D.C., and Christen A.G. Dental and oral
effects observed in a long-term tobacco chewer: Case report. J. Indian
  Dent. Assoc. 62: 17-18, 1983.

(14) Axell, T., Momstad. H., and Sundstrom, B. The relation of the clinical
  picture to the histopathology of snuff dipper's lesions in a Swedish
  population. J. Oral Pathol. 5: 229-236, 1976.
(15) Pindborg, J.J., and Renstrup, G. Studies in oral leukoplakias, II. Effect
  of snuff on oral epithelium. Acta Derm. Venereol. 4.X: 271-276, 1963.
(16) Pindborg, J.J., and Poulsen, H.E. Studies in oral leukoplakias, I. The
  influence of snuff upon the connective tissue of the oral mucosa.
  Preliminary report. Acta Pathol. Microbial. Immunol. Stand. 55:
  412-414, 1962.

(17) Axell, T. A prevalence study of oral mucosal lesions in an adult Swedish
  population. Odontol. Rev. (Suppl. 36) 27: l-103, 1976.
(18) Hirsch, J.M., Heyden, G., and Thilander, H. A clinical histomorphologi-
  cal and histochemical study on snuff-induced lesions of varying sever-
  ity. J. Oral Pathol. 11: 387-398, 1982.
(19) Frithiof, L., Anneroth. G., Lasson, U., and Sederholm, C. The snuff-
  induced lesion. A clinical and morphological study of a Swedish
  material. Acta Odontol. Stand. 41: 53-64, 1983.
(20) Greer, R.O., Poulson, T.C., Boone, M.E., Lindenmuth, J., and Crosby,
  L.K. Smokeless tobacco associated oral changes in the juvenile, adult,
  and geriatric patients: Clinical and histomorphologic features including
light microscopic, immunocytochemical and ultrastructural findings.
  Gerodontics 2: 3, 1986.

(21) Jungell, P., and Malmstrom, M. Snuff-induced lesions in Finnish
  recruits. Stand. J. Dent. Res. 93: 442-447. 1985.
(22) Van Wyk, C.W., The oral lesion caused by snuff. A clinics-pathological
  study. Medical Proceedings II: 531-537, 1966.
(23) Archard, H.O., and Thrpley, T.M.. Jr. Clinicopathologic and histo-
  chemical characterization of submucosal deposits in snuff dipper's
  keratosis. J. Oral Pathol. 1: 3-11, 1972.
(24) Smith, J.F. Snuff-dippers lesion. A ten-year follow-up. Arch.
  Otolaryngol. 101:276-277, 1975.

(25) Brightman, V.J. Laboratory procedures. In: Malcolm A. Lynch (ed).
  Burket's Oral Medicine-Diagnosis and `Beatment. Philadelphia, J.B.
  Lippincott Company, 1977, pp. 723-724.
(26) Mehta, F.S., Gupta, P.C., and Pindborg, J.J. Chewing and smoking
  habits in relation to precancer and oral cancer. J. Cancer Res. Clin.
  Oncol. 99 35-39, 1981.

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(27) `Qldesley, W.R. Tobacco chewing in English coahniners (2). Malignant
  transformation in a tobacco-induced leukoplakia. Br. J. Oral Surg. 14:
  93-94, 1976.

(2.9) Roed-Petersen, B, and Pindborg, J.J. A study of Danish snuff-induced
oral leukoplakia. J. Oral Pathol. 2: 301-313, 1973.
(29) Vogler, W.R., Lloyd, J.W., and Mihnore, B.K. A retrospective study of
etiological factors in cancer of the mouth, pharynx, and larynx. Cancer
  15: 246-258, 1962.

(30) McGuirt, W.F. Snuff dipper's carcinoma. Arch. Otolaryngol. 109:
  757-760, 1983.

(31) Sundstrom, B., Momstad, H.. and AxelI, T. Oral carcinomas associated
with snuff dipping. Some clinical and histological characteristics of 23
  tumours in Swedish males. J. Oral Pathol. 11: 245-251,1982.
(32) Rosenfeld, L., and Cahaway, J. Snuff dipper's cancer. Am. J. Surg. 106:
  840-844, 1963.

(33) Landy, J.J., and White, H.J. BuccogingivaI carcinoma of snuff dippers.
  Am. Surg. 27: 442-447,196l.

(34) Banndczy, J., and Sugar, L. Progressive and regressive changes in
Hungarian oral leukoplakias in the course of longitudinal studies. Com-
  munity Dent. Oral Epidemiol. 3: 194-197, 1975.
(35) Pindborg, J.J., Reibel, J., and Hohnstrup, P. Subjectivity in evaluating
oral epithehal dysplasia, carcinoma in situ and initial carcinoma. J. Oral
  Pathol. 14: 698-708. 1985.

(36) Mod&, T., Lavstedt, S., and Ahlund, C. Relation between tobacco con-
sumption and oral health in Swedish schoolchildren. Acta Odontol.
  Stand. 38: 223-227, 1980.

(37) Hecht, S.S., Chen. C.B., Hirota, N., Omaf, R.M., and `Iho, T.C. Tobacco-
specific nitrosamines: Formation from nicotine in vitro and during
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  Inst. 60: 819-824, 1978.

(38) Sitzes, L. On chewing tobacco. ADA News 8: 2, 1981.
(39) Croft, L. Smokeless tobacco: A case report. Tex. Dent. J. 99: 15-16,
  1981.

(40) Shannon, I.L., and `RodahI, J.N. Sugars and fluoride in chewing tobac-
  co and snuff. Tex. Dent. J. 96: 6-9, 1981.

(41) Going, R.E., Hsu, S.C., Pollack, R.L., and Haugh, L.D. Sugar and
  fluoride content of various forms of tobacco. J. Am. Dent. Assoc. 100:
  27-33, 1980.

(42) Hsu, SC., Pollack, R.L., Hsu, A.F., and Going, R.E. Sugars present in
  tobacco extracts. J. Am. Dent. Assoc. 101: 915-918, 1980.

(43) Lindemeyer. R.G., Baum, R.H., Hsu, S.C., and Going, R.E. In vitro ef-
fect of tobacco on the growth of oral cariogenic streptococci. J. Am.
  Dent. Assoc. 103: 719-722. 1981.

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(44) Falkler, W.A., and Zimmerman, M.L. Effect of smokeless tobacco ex-
tracts on the growth of streptococcus mutans. Presented at the Annual
Meeting of the International Association of Dental Research, Las
Vegas, Nevada, March 1985.

(45) Christen, A.G. The case against smokeless tobacco: Five facts for the
health professional to consider. J. Am. Dent. Assoc. 101: 464-469,198O.
(46J U.S. Department of Health and Human Services. Draft report to the
Surgeon General by the Inspector General on smokeless tobacco.
  December 20, 1985.

(47) Waldron, C.A., and Shafer, W.G. Leukoplakia revisited. A clinicopatho
logic study of 3,256 oral leukoplakias. Cancer 36: 1386-1392, 1975.
(48) Waldron, C.A., and Shafer, W.G. Current concepts of leukoplakia. Int.
  Dent. J. 10: 350-367, 1960.

(49) Shafer, W.A., Hine, M.K., and Levy, B.M. Oral Pathology, ed. 2.
Philadelphia, W.B. Saunders Co., 1969, pp. 80-81, 85.
/So) Liie, H.. and Silness, J. Periodontal disease in pregnancy. I. Prevalence
and severity. Acta Odontol. Stand. 21: 533-551. 1963.

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Chapter 4.

    NlCOTlNE EXPOSURF'
PHARMACOKINmCS, ADDICTION,
AND OTHER PHYSIOLOGIC EFFECTS


CONTENTS

Introduction .,,...................................141

Pharmacokinetics of Nicotine
  Levels of Nicotine in Smokeless Tobacco
Absorption of Nicotine
  Distribution of Nicotine
  Nicotine Elimination
  Nicotine and Cotinine Levels in Users of
   Smokeless Tobacco
Time Course of Nicotine `Bunover During
  Daily lbbacco Use
  References

 141

 141

 141

 142

 142

 143

 143

 143

Nicotine Addiction Associated With
Smokeless lbbacco Use
Background and Definitions
  Commonahties Between Ibbacco Use and Other
   Addictive Substances
Experimental Studies of the Abuse Liability and
  Physical Dependence Potential of Nicotine
Evidence That Orally Delivered Nicotine (Including
  Via Smokeless lbbacco) Has a Liability for Abuse
  and a Potential to Produce Physical Dependence
References.......................................

144
144

146

157

166
168

Physiologic and Pathogenic Effects of
Nicotineand Smokeless l'Uxcco
Physiologic Effects of Nicotine
Nicotine, Smokeless Tobacco, and
   Human Diseases .
  NonnicotineRelated Adverse
  Metabolic Consequences
  References











  

175
175

176

179
,179

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...182

ResearchNeeds....................................184

139


This chqter examin es the consequences of exposure to nicotine from
smokeless tobacco. It draws from the vast literature on the effects of
nicotine delivered via smoking and intravenously and includes recent
evidence of the effects of orally delivered nicotine.

The first section describes the pharmacokinetics of nicotine, includ-
ing absorption, distribution, and elimination. The data presented indi-
cate that nicotine is present in smokeless tobacco in significant
amounts and that users attain blood levels of nicotine similar to those
produced by cigarette smoking.

The second section reviews the established evidence that nicotine is
an addictive and dependenceproducing substance, having a number of
important characteristics in common with prototypic addictive and
dependenceproducing substances, as well as substantial experimental
evidence of its abuse liability and dependence potential. Given the nice
tine content of smokeless tobacco, its ability to produce high and sus-
tained blood levels of nicotine, and the well-established data implicating
nicotine as an addictive substance, one may deduce that smokeless
tobacco is capable of producing addiction in users. In addition, very re-
cent studies provide direct confirmation that nicotine delivered orally
from smokeless tobacco and nicotine chewing gum is addictive, produc-
ing abuse liability and dependence potential.

The final section of the chapter reviews the multisystem physiologic
effects of nicotine and examin es the evidence pertaining to the potential
contributory role of nicotine in the causation of several diseases.

PHARMACOKINETICS OF NICOTINE

Levels of Nicotine in Smokeless Tobacco

`Ibbacco is a plant product, and therefore differences exist in nicotine
content among and within different strains of tobacco. Nicotine content
among smokeless tobacco products also differs: moist snuff contains
4.56 to 15.1 mg nicotine per gram (1); plug tobacco has been measured to
contain 17.2 mg per gram (2). Assuming a daily consumption of 10
grams of smokeless tobacco, the habitual user can be exposed to
roughly 130 to 250 mg nicotine per day, of which varying amounts may
be absorbed. By comparison, cigarette tobacco averages 15 mg nicotine
per gram or 9 mg nicotine per cigarette (3). A person who smokes a pack
of cigarettes per day therefore can be exposed to 180 mg nicotine per day.

Absorption of Nicotine

Nicotine is a weak base (pKa 7.9). In its ionized form, as in the acidic
environment of most cigarette smoke, nicotine crosses membranes
poorly. As a consequence, there is virtually no buccal absorption of nice

141


tine from cigarette smoke. In contrast, smokeless tobacco products are
buffered to an alkaline pH that facilitates absorption.

The rate of absorption of nicotine from smokeless tobacco depends on
the product and the route of administration. With fineground nasal
snuff, blood levels of nicotine rise almost as fast as those that are
observed after cigarette smoking (4). The rate of nicotine absorption
with the use of oral snuff (and presumably chewing tobacco) is more
gradual (5).

People who use oral smokeless tobacco, particularly those who chew
tobacco, generate large amounts of saliva, some of which is expecto
rated and some of which is swallowed. Due to first pass metabolism in
the liver following absorption from the intestines, the bioavailability of
swallowed nicotine is approximately 30 percent (6). By changing how
much is chewed, how much is held inside the mouth, and how much
saliva is expectorated or swallowed, the user of smokeless tobacco has
considerable control over the dose of nicotine that is absorbed.

Distribution of Nicotine

Smoking is a unique form of drug administration in that entry into
the circulation is through the pulmonary rather than the portal or sys-
temic venous circulations. The lag time between smoking and the
appearance of nicotine in the brain is even shorter than after intrave-
nous injection. Nicotine enters the brain quickly, but then brain levels
decline rapidly as it is distributed to other body tissues. The rapid brain
uptake of nicotine from smoking allows easy puff-topuff titration of
desired nicotine effects and partly may explain the highly addictive
nature of cigarette smoking.

In contrast, the concentrations of nicotine that enter the brain from
smokeless tobacco use are likely to be lower (6), and the pharmacologic ef-
fects may differ. The rate of exposure to psychoactive drugs is an impor-
tant determinan t of their effects. Thus there could be differences in the ef-
fects of nicotine that is taken by smoking compared to using smokeless
tobacco, even with the same average body concentrations of nicotine.

Nicotine Elimination

Nicotine is rapidly and extensively metabolized primarily in the liver
but also to a small extent in the lung and kidney. Renal excretion
depends on urinary pH and urine flow and accounts for 2 to 35 percent
of total elimination (78). The half-life of nicotine averages 2 hours,
although there is considerable individual variability that ranges from 1
to 4 hours (9). The major metabolites of nicotine are cotinine and
nicotineN-oxide. Neither metabolite appears to be pharmacologically
active (8). Because of its long half-life, cotinine is commonly used as a
marker of nicotine intake in survey and cessation studies. It should be
recognized, however, that first pass metabolism of swallowed nicotine

142


may result in wtinine levels that are disproportionately higher than
nicotine levels with the use of smokeless tobacco compared to the use of
cigarettes.

Nicotine and Cotinine Levels in
Users of Smokeless Tobacco

Blood or plasma concentrations of nicotine in cigarette smokers who
were sampled in the afternoon generally ranged from 10 to 50 ng/ml (10).
The increment in blood nicotine concentration after a single cigarette is
smoked ranges from 5 to 30 ng/ml, depending on how the cigarette is
smoked (llJ2).

In users of moist oral snuff or chewing tobacco, the levels of nicotine
increase an average from 2.9 to 21.6 ngiml during 8 hours of repeated
use (1). In habitual users of nasal snuff, blood levels of nicotine increased
on average by 12.6 ng/ml after a single dose of snuff, and levels aver-
aged 36 nglml after multiple doses (4). Similarly, blood cotinine concen-
trations averaged 197 ng/ml and 411 ng/ml in groups of oral and nasal
tobacco users, respectively, compared to an average cotinine level of
300 q/ml for cigarette smokers described in many studies 11,4). These
comparisons indicate that the intake of nicotine and nicotine levels in
habitual users of smokeless tobacco are similar to those that are ob-
served in habitual cigarette smokers.

Time Course of Nicotine Turnover During
Daily Tobacco Use

Tobacco use is commonly considered to be a process of intermittent
dosing of nicotine, which in turn is rapidly eliminated from the body.
Smoking produces considerable variations from highest to lowest blood
nicotine levels from one cigarette to the next cigarette. However, con-
sistent with a half-life of 2 hours, nicotine accumulates over 6 to 8 hours
of regular smoking, and nicotine levels persist overnight, even as the
smoker sleeps (13). The same accumulation is probable with repeated
smokeless tobacco use. Thus as with the smoker, the smokeless tobacco
user may be exposed to nicotine for 24 hours each day.

References

(1) Hoffmann, D., Harley, N.H., Fisenne, I., Adams, J.D., and Brunne
mann, K.D. Carcinogenic agents in snuff. JNCI 76: 435-437,1986.
(2) Hoffmann, D., Hecht, S.S., Omaf, R.M., Wynder, E.L., and Tso, T.C.
Chemical studies on tobacco smoke. XLII. Nitrosonornicotine:
Presence in tobacco, formation and carcinogenicity. In: E.A. Walker, P.
Bogovski, and L. Griciute (eds.). Environmental N-Nitroso Com-
pounds. Analysis and Formation (IARC Scientific Publications No. 14).
Lyon, France, International Agency for Research on Cancer, 1976, pp.
  307-320.

143


(3) Benowitz, N.L., Hall, S.M., H eming, R.I., Jacob, P., III, Jones, R.T.,
and Osman, A.L. Smokers of low-yield cigarettes do not consume less
nicotine. N. Engl. J. Med. 309: 139-142, 1983.
(4) Russell, M.A.H., Jarvis, M.J., Devitt, G., and Feyerabend, C. Nicotine
intake by snuff users. Br. Med. J. 283: 814-817, 1981.
(5) Russell, M.A.H., Jan&, M.J., West, R.J., and Feyerabend, C. Buccal
absorption of nicotine from smokeless tobacco sachets. Lancet 8468:
1370, 1985.

(6) Jenner, P., Gorrod. J.W., and Beckett, A.H. The absorptionof nicotine
1 `-N-oxide and its reduction in the gastrointestinal tract in man. Xeno-
biotica 3: 341-349, 1973.
(7) Beckett, A.H., Gorrod, J.W., and Jenner, P. A possible relation be
tween pKa and lipid solubility and the amounts excreted in urine of
some tobacco alkaloids given to man. J. Pharm. Pharmacol. 24:
115-120, 1972.

(8) Benowitz, N.L., Kuyt, F., Jacob, P.. Jones, R.T., and Osman, A-L. Coti-
  nine disposition and effects. Clin. Pharmacol. Ther. .%5? 139142,1983.
(9) Benowitz, N.L., Jacob, P., III, Jones, R.T., and Rosenberg, J. Inter-
  individual variability in the metabolism and cardiovascular effects of
  nicotine in man. J. Pharmacol. Exp. Ther. 221: 368-372,1982.
(10) Russell, M.A.H., Jarvis, M., Iyer, R., and Feyerabend, C. Relationship
  of nicotine yield of cigarettes to blood nicotine level concentration in
  smokers. Br. Med. J. 280: 972-976, 1980.
(11) Armitage, A.K., Dollery, C.T., George, C.F., Houseman, T.H., Lewis,
  B.J., and timer, D.M. Absorption and metabolism of nicotine from
  cigarettes. Br. Med. J. 4: 313-316, 1975.
(12) Herning, R.I.. Jones, R.T., Benowitz, N.L.. and Mines, A.H. How a
  cigarette is smoked determines nicotine blood levels. Clin. Pharmacol.
  Ther. 33 84-91, 1983.

(13) Benowitz, N.L., Kuyt, F., and Jacob, P., III. Circadian blood nicotine
  concentration during cigarette smoking. Clin. Pharmacol. Ther. 32:
  758-764. 1982.

NICOTINE ADDICTION ASSOCIATED WITH
SMOKELESS TOBACCO USE

Background and Definitions

Clinical observations and data, historical anecdotes, and sworn testi-
mony all support the conclusion that some users of smokeless tobacco
are unable to abstain permanently from smokeless tobacco, even when
iIl health is apparent (1). Such observations suggest that smokeless
tobacco use can become a form of drug addiction or dependence.*

o The terms "addictnn and dependence" will be used almost interchangeably throughout this section While man
argue the value of one of these terms over the other, it is im  i-tam to note that in the context of this chapter ???? B
               f&                B
dress the questkon of whether ruwtine resulting from smo   or smokeless tobacco use leads an individual to lose
voluntary control over bk or her use of t&acco products (i.e.. does the drug cause either dependence or addiction).

144


This section of the report will evaluate the scientific evidence that
smokeless tobacco is an addictive substance whose use results in drug
dependence. Drug dependence as used in this review is defined in accor-
dance with the World Health Organization's Expert Committee on
Drug Dependence (2) and other recognized sources (3). Drug dependence
is substanceseeking behavior that is controlled by the activity of a con-
stituent drug in the central nervous system and displaces other
behavior such that drug seeking assumes greater priority. IUzrance
and physiologic withdrawal may or may not be present (23). and the
severity of dependence may vary considerably among individuals.
The scientific standard for classifying a drug as likely to cause addic-
tion or dependence is based on the degree to which "abuse liability" and
"physical dependence potential" are present. Both terms are accepted
terminology of the Committee on Problems of Drug Dependence and
the Addiction Research Center (ARC) of the National Institute on Drug
Abuse (4,5F and are commonly accepted to refer to drugs whose actions
are mediated by the central nervous system Abuse liability refers to
drug effects that contribute to compulsive self-administration, often in
the face of excessive financial cost, physical and social dysfunction, and
the exclusion of more socially acceptable behaviors (56). Physical
dependence potenti (also referred to as physiological dependence
potential) pert&s to the direct physiologic effects that are produced by
the repeated administration of a drug that results in neuroadaptation
(34). Neuroadaptation is characterized by demonstrated tolerance to
the effects of the drug and the occurrence of physiologic withdrawal
signs following the termination of drug administration.
Physiologic or physical dependence, as evidenced by physiologic and
behavioral rebound (withdrawal) effects, is neither necessary nor suffi-
cient to define drug dependence (35). Nevertheless, the process of drug
dependence and abuse entails physical components, including physical
interactions between drug and tissue in the central nervous system
(specific receptors in the case of some drugs such as nicotine and
opioids) that are critical~
Three lines of evidence are important to assess the abuse liability and
physical dependence potential of smokeless tobacco use. The first in-
volves inference from the systematic comparison of tobacco use (includ-
ing smokeless forms) to the use of prototypic dependenceproducing
drugs (e.g., alcohol, morphine, and cocaine) to determine whether the

t A concept that is central to many discussions of drug de
                 8" dence is that the substance reduces damage or
debilitation. This asp& of tob.scco dependence will not be a dressed here because extensive 8. ta already exist in-
dicnting the actual toxicity of tobacco and there is widespread recognition even by tobacco users that the sub
stance I.3 harmful.

145


patterns of tobacco use, as well as the behavioral and physiologic effects
of such use, are similar to those of the prototypic dependenceproducing
drugs. This issue is discussed below in the section entitled "Commonali-
ties Between Tobacco Use and Other Dependence-Producing
Substances."

The second line of evidence emerges from recent studies in which
nicotine was evaluated using the same methods and criteria that have
been used to evaluate any substance that is suspected of causing abuse
and physical dependence. This deductive approach evaluates whether
nicotine meets rigorous experimental criteria as a drug that has sub
stantive liability for abuse and physical dependence potential. This
issue is discussed in the section entitled "Experimental Studies of the
Abuse Liability and Dependence Potential of Nicotine."
The third line of evidence comes from recently completed studies that
involve direct assessments of the abuse liability and dependence poten-
tial of orally given nicotine. E xamination of these studies provides indi-
cations of whether the consumption of nicotine through oral forms of
administration delivers pharmacologically active quantities of nicotine
to the bloodstream and whether smokeless tobacco itself meets specific
criteria for abuse liability and dependence potential. This issue is dis-
cussed in the section entitled "Evidence That Orally Delivered Nicotine
(Including Smokeless Tobacco) Has a Liability for Abuse and a Poten
tial to Produce Dependence. "
Taken together, the first and second lines of evidence support the con-
clusion that smokeless tobacco contains an addictive substance. The
third line of evidence suggests that delivery of the addictive substance
(nicotine) in the form of smokeless tobacco does not alter its addictive
properties.

Commonalities Between Tobacco Use and
Other Addictive Substances

The assertion that tobacco use can occur as a form of drug addiction
rests firmly on the observed commonalities between the use and effects
of tobacco and the use and effects of addictive substances such as alto
hoi, opium, and coca. Systematic reviews of these commonalities have
been published (%ll), and the major points that tobacco and addictive
substances have in common are as follows:

o A centrally (CNS) active substance (drug) is delivered.
o Discriminative (subjective) effects are centrally mediated.

o The substance (drug) is a reinforcer for animals.
o The patterns of acquisition and maintenance of substance inges-

tion are orderly.

o The patterns of self-administration of the substance are orderly.

146


o The patterns of self-administration of the substance vary as a func-
tion of the dose that is consumed.

o Tolerance to the behavioral and physiologic effects of the sub
stance develops with repeated use (neuroadaptation).

o Therapeutic effects may be produced by the substance.
o The treatment of addiction resulting from the substance (drug)
involves similar strategies.

The evidence concerning tobacco and these factors is presented in the
following subsections.

`Ibbacco Use Delivers a Centrally Active Substance-Nicotine

The fundamental commonality between tobacco use and the use of
known addictive substances is the delivery of a chemical to the central
nervous system The primary agent in tobacco, nicotine, is delivered to
the central nervous system in all commonly used forms of tobacco (12).
The fact that cigarette smokers will substitute smokeless tobacco,
when cigarettes are not available or when the use of combustibles is
restricted, certainly suggests that different forms of tobacco use pro
duce acceptably similar effects for the user (13).

. . .
Dmnmmative Effects of Nicotine Are Centrally Mediated

Nicotine, like other drugs of abuse, produces doserelated effects in
animals, which an be attenuated by centrally acting antagonists (1416).
When the animals confuse these effects with other drugs (i.e., effects
partially generalize to other drugs of abuse), it is more likely to be a drug
like amphetamine rather than a sedativelike drug (17). These findings
are also consistent with data derived from studies with humans in
which the doserelated effects of intravenously given nicotine were
attenuated by mecamylamine pretreatment (18).

Nicotine Is a Reinforcer for Animals

Most drugs that are abused by humans are voluntarily self-
administered when they are made available to animals in laboratory
studies; in other words, the drug serves as a reinforcer or a reward
(19,20). Such findings confirm that the physiologic effects of the drug in
the central nervous system are sufficient for the substance to control
behavior by virtue of its reinforcing effects. Definitive studies ???? were
undertaken in the early 1980's support this statement. As seen in table
1, nicotine has now been shown to function as a reinforcer for five non-
human animal species and under a variety of conditions (21,227. F'urther-
more, its functional behavioral effects are similar to those engendered
when other drugs of abuse (e.g., cocaine) serve as reinforcers.

Patterns of Acquisition and Maintenance of Tobacco Use Are Orderly
The use of tobacco, like that of prototypic addictive substances, is
often initiated due to peer influences (2.5). The contribution of social

147


TABLE I.-Summary of Reports in Which Nicotine Was Available
     Under Intravenous Drug Self-Administration Procedures

Study

SpC!CieS

Reinforcement
Schedule

Main Finding

Comment

Deneau    Rhesus
and Inoki  Monkey
(19371

Yanagita,   Rhesus
Ando,    Monkey
OiIlUIIUl,
and Ishida
(1974)

Lang.     Hooded
Latiff.     Rat
McQueen.
and Singer
(1977)

Singer,    Hooded
Simpson, Rat
andLang
(1973)

Fixed-ratio 1
(FR 1). Several
doses of nicotine
were tested.

Experiment 1:
FR 1. Several
doses of nicotine
and lefetamine
and saline were
t&MI.

Nicotine did not   -
serve as a
reinforcer when
compared to saline
or lefetamine.

Experiment 2:    Stable rates of   No direct test of
FR 1. Several     nicotine S-A    reinforcing
doses of nicotine   occurred in most  efficacy was done.
were continuously  subjects but were
available for at   not clearly related
least 4 weeks.    to dose.

Experiment 3:
Progressive ratio
(PR) procedures.
`ho doses of
nicotine and saline
and three doses of
cocaine were
teSti.

At 0.2 mg/kg nice Nicotine was
tine, response   marginaNy rein-
rates slightly    forcing when
exceeded those   compared to
maintained by    cocaine.
dine or the
lowest cocaine
dose (0.03 mg/kg).

FR 1. Nicotine
and saline were
tested in food-
sated and food-
deprived rats.

Concurrent [(FR 1:
nicotine). (Fixed-
time 1 min.: food
pellet)] in food-
deprived rats.
Subsequently, the
rats were food-
sated.

Two monkeys   Currently
initiated self-    accepted criteria
administration   to assess reinforc-
(S-A); the others  ing efficacy were
required a prim-   not achieved.
ing procedure.

In food-deprived -
(but not food-
sated) rats,
nicotine was a
reinforcer when
compared to
saline.

Food satiation    Results were simi-
decreased rate of  lar to those
nicotine S-A, how- obtained when
ever, nicotine was rats were similarly
a reinforcer in    tested with
both conditions.   ethanol.

148


TABLE l.-Continued

Study    Species

Reinforcement
Schedule

Main Finding

Comment

Griffiths,   Baboon
Brady, and
Bradford
(1979)

Hanson,   Albino Rat
Iveskr,
and
Moreton
(1979)

Latiff,     Hooded
Smith, and Rat

Smith and Hooded
L=%     Rat
(1980)

Goldberg, Squirrel
Speahnan, Monkey
and
Goldberg
(1981)

FR 160 followed
by 3-hr. timeout.
Several doses of
nicotine and saline
were substituted
for cocaine.

FR 1. Several
doses of nicotine
and saline were
teSti.

Cone (FR 1: injec-
tion) (FT 1 min.:
food pellet).
Several doses of
nicotine and
saline were
teSti.

FR 1. One dose of
nicotine and saline
were tested.

Second order
schedule FI 1 or
2 min. (FR 10:
stimulus) followed
by 3-min. timeout.
One dose of nico-
tine and saline
was tested.

Number of nice-
tine injections
per day did not
exceed that of
saline.

Mecamylamine
(centrally acting
antagonist) but
not pent&km
(peripherally act-
ing antagonist)
altered S-A
behavior.

Nicotine was a
reinforcer relative
to saline. Urine
pH manipulations
had mild effects
on rate of S-A
only during initial
exposure to
nicotine.

Nicotine was
established as a
reinforcer both
with and without
a concurrent food
delivery schedule

Caffeine,
ephedrine, and a
variety of other
similarly tested
stimulants did
serve as rein-
forcers relative to
saline in this
paradigm.

Group data
suggest that
nicotine was a
reinforcer;
however, there
was no clear dose
effect curve.

Rate of S-A was
inversely related
to dose during
initial exposure to
nicotine but not
after nicotine S-A
was established.

-

in food-deprived
but not food-sated
rats.

Nicotine main-    Demonstrated the
tained high rates  importance of
of responding.   ancillary environ-
Rates decreased   mental stimuli in
markedly when (1) maintaining high
saline replaced    rates of
nicotine, (2) the  responding.
brief stimuh were
omitted, and (3)
subjects were
pretreated with
mecamylamine.

149


TABLE l.-Continued

Study    Species

Reinforcement
Schedule

Main Finding

Comment

Ator and   Baboon
Griffiths
(1981)

Dougherty, Rhesus
Miller. -  Monkey
Todd, and
Kosten-
bauder
(1981)

Goldberg
and
Spealman
(1982)

Singer,
Wallace,
and HalI
(19821

Squirrel
Monkey

Long
Evans Rat

FR 2 followed by   Nicotine was
15-sec. timeout.   marginally rein-
Several doses of   forcing compared
nicotine and saline  to saline across a
and cocaine were   narrow dose
tested.         range.

FI 16 and second
order FI 1 min.
(FR 4: stimulus).
Several doses of
nicotine and saline
were tested.

FI 5 min. Several
doses of nicotine
and cocaine and
saline were tested.

CONC [FR 1:
nicotine) (FT 1
min.: food pellet)].
One dose of
nicotine was
tf?Skd.

Nicotine main-
tained higher
rates of S-A than
saline under the
FI and second
order schedules
but was only a
margjnally effec-
tive reinforcer
when continu-
ously available.

Nicotine and

Initial dose
response curve
was inverted
U-shaped, and
final dose
response curve
was flat (from
abstract of study).

Establishment of
nicotine as a rain-
forcer required
several months
using procedures
that typically
require only a few
days to establish
cocaine or codeine
as reinforcers.

This study also

cocaine were quali- showed that
tatively similar   nicotine could
reinforcers when   serveasa
compared to    punisher similar to
saline. Cocaine   electric shock.
maintained higher
rates of respond-
ing in one of two
monkeys. Meca-
mylamine pre-
treatment reduced
rates of nicotine
S-A.

A group of rats   Extended the
with 6-OHDA   range of
lesions in the    scheduled-induced
nucleus accum-   behaviors that are
hens S-A nicotine  inhibited by such
at lower rates    lesions.
than a sham-
lesioned group.

150


TABLE l.-Continued

Study    Species

Reinforcement
Schedule

Main Finding

Comment

Spealman
and
Goldberg
(1982)

Risner and
Goldberg
(1983)

Henning-
field,
Miyasato,
and
Jasinski
(1983)

Goldberg
and
Henning
field
(1983)

Squirrel
Monkey

Beagle
Dog

Human
and
Squirrel
Monkey

Second order FI 1,
2, or 5 min. (FR 10
stimulus) and FI 5
min. schedules
were tested.
Several doses of
nicotine and
cocaine and saline
were tested.

FR 15 followed by
4 min. timeout.
Several doses of
nicotine, cocaine,
and saline were
tested. Progres-
sive ratio schedule
was used.

FR 10 followed by
1 min. timeout.
Several doses of
nicotine and saline
were tested.

FR 10 followed by
1 min. timeout.
Several doses of
nicotine and saline
were tested.

Nicotine and     Nicotine's rem-
cocaine main-    forcing efficacy
tained similar   was comparable to
patterns of      that of cocaine.
responding on the
schedules. Nice
tine, but not
cocaine S-A,
decreased to
salinelike rates
when animals were
pretreated with
mecamylamine.

Nicotine and     Cocaine main-
cocaine main-    tained substan-
tained qualita-   tially greater
tively similar    response rates
patterns of      than nicotine.
responding and
were reinforcers
relative to saline.
Mecamylamine
pretreatment
reduced nicotine
but not cocaine
S-A.

Number of nice  Nicotine produced
tine injections   subjective effects
generally ex-     similar to those
ceeded number of produced by intra-
saline injections   venous cocaine
and were inversely and had both rein-
related to nicotine forcing and
dose. Post-session punishing effects.
cigarette smoking
was suppressed
by nicotine.

Patterns of      In both the
responding were   human and mon-
qualitatively    key subjects,
similar in both   there was evidence
species. Number  that nicotine func-
of nicotine injec-   tioned with both
tions exceeded   reinforcing and
number of saline  punishing
injections in 3 of  properties.
4 human and 3 of
4 monkey subjects.

151


support to the initiation of tobacco use may be even greater than with
illicit drugs, because family members, other social models, and advertis-
ing often tolerate, approve, or promote tobacco use while disapproving
the use of some nonprescription drugs (`4). Also, as is the case with
addictive drugs, an accelerated pattern of development of tobacco use
has been observed, which is followed by relatively stable drug intake.
Initially, the level of consumption increases gradually from the first day
of use until some point, perhaps several years later, when it becomes
relatively stable over time. Although many factors can operate to pro
duce such a biphasic pattern of intake, it is generally assumed that
tolerance and learnin g factors account for the gradual acceleration and
that a level of optimum drug effect combined with toxicity and adverse
effects at higher doses takes over to produce the stabilization phenome
non. A preliminary survey, conducted at Johns Hopkins University,
indicates that nicotine, whether administered as cigarette smoke or
smokeless tobacco, does not differ from other drugs in this regard. That
is, tobacco users tend to begin smoking a few cigarettes a day or con-
sume a portion of a container of smokeless tobacco each day and gradu-
ally increase consumption levels over a period of months or even years
before they stabilize the amount they finally use (personal communica-
tion, J.E. Henningfield).

Patterns of Tobacco Self-Administration Are Orderly

Daily patterns of cigarette smoking are orderly. Addicted smokers
tend to smoke their first cigarette within 30 minutes of waking from a
night of sleep and find it difficult to abstain from tobacco use for more
than a few hours (2.5). If smoking behavior is relatively unconstrained,
regular patterns develop that closely resemble those of psychomotor
stimulant self-administration in animals (20). Similar orderly patterns
of tobacco self-administration are evident with cigarette smoking by
humans. Several studies have demonstrated that across successive
puffs on a cigarette, puff duration decreases and interpuff intervals
tend to increase (26,27,2-!$29), although these changes are multifactor-
ially determined (30). Anecdotal reports by smokeless tobacco users
suggest that while consumption patterns are necessarily different (e.g.,
some keep a plug in their mouth almost continually during their waking
hours) they are no less regular and orderly.

Tobacco Self-Administration Varies as a Function of Nicotine Dose

The effective dose of a substance may be varied by changing the
quantity of drug per unit (the unit dose), by pretreating the individual
(animal or human) with either an agonist or antagonist, or by altering
the rate of elimination of the substance. Studies that involve these three
manipulations have been done extensively with other drugs and more
recently with nicotine, The results across study, drug, and species are
remarkably similar. For general reviews of human and animal studies

152


see Griffiths, Bigelow, and Henningfield (20) and Henning-field, Lukas,
and Bigelow (31). See Gritz (32) and Henningfield (33) for recent reviews
of the nicotinespecific literature. Over a wide range of dose levels, fre
quency of self-administration is inversely related to dose but drug in-
take is directly related to dose, reflecting partial compensatory changes
(26,32). Pretreatment with other agonists (or forms of nicotine) reduces
drug taking, e.g., decreases cigarette smoking, (34) and reduces pre
ferred nicotine concentration of tobacco smoke (35). Pretreatment with
antagonists initiaIly increases drug self-administration. For example,
the centrally and peripherally acting ganglionic blocker, mecamyla-
mine, but not the peripherahy acting blocker, pentolinium, increases
subsequent smoking rates and increases preferred nicotine concentra-
tions of tobacco smoke (36,37). In addition, altering the elimination rate
of nicotine alters the amount of nicotine that is self-administered in the
form of tobacco smoke (38).

There has been debate over the degree to which smokers regulate
their nicotine intake, i.e., the "titration" hypothesis. It is now generally
agreed that smokers do not precisely titrate their nicotine intake any
more than animals titrate their intake of reinforcing drugs (except
under extremely limited conditions) or humans titrate their intake of
other reinforcing drugs (20). However, when dose manipulations are
observed and objective, sensitive dependent variables are measured in
both animals and humans (26,32,33), most of the studies demonstrate an
increase in smoking as cigarette nicotine content falls below accus-
tomed levels and a decrease in smoking when cigarette nicotine content
is unusually high (32). Kozlowski and his coworkers describe these find-
ings in terms of a "boundry" model of dose compensation (39).

Tolerance of Nicotine Develops With Repeated Use (Neuroadaptation)
The administration of mostdrugs of abuse results in neuroadaptation
as measured by tolerance to the repeated administration of the drug
and a subsequent rebound (withdrawal) when drug administration is
terminated (3). Tolerance to drug effects is determined either by the
diminished response to repeated doses of a drug or the requirement of
increasing doses to achieve the same drug effect. Tolerance to the
behavioral and physiologic effects of nicotine has been studied for
decades (33). As is the case with other drugs of abuse, a variety of
mechanisms accounts for tolerance to many of nicotine's effects, includ-
ing metabolic (40), behavioral (41#), and physiologic tolerance (44-46).
More recently, studies have shown that the effects of nicotine that are
suspected to be critical to the addiction process also show tolerance
with repeated dosing (4799.

Physiologic dependence on drugs is determined by showing that ter-
mination of drug administration produces a syndrome of effects that is
generally opposite to those produced by drug administration. This syn-
drome is reversible, at least in its early stages, by administration of the

153


drug. Prolonged drug abstinence (detoxification) results in ultimate
return to baseline (normal) values of behavioral and physiologic frmc-
tions. It is now clear that repeated tobacco administration produces
physiologic dependence that is specifically due to nicotine administra-
tion. Recent data that confirm this fact are reviewed in the section on
Dependence Potential of Nicotine.

Nicotine Produces Therapeutic Effects

Most drugs of abuse have specific therapeutic applications; nicotine
is no exception (4850). The degree to which the therapeutic effects of
nicotine depend upon the individual's history of nicotine use, as opposed
to the possibility that nicotine is efficacious for preexisting conditions,
remains to be investigated. Similar issues are true for other drugs of
abuse as well. Pomerleau and his coworkers (51) have studied a variety
of mechanisms by which the possibly weak, initial reinforcing effects of
nicotine can be greatly strengthened by subtle effects on mood, cogni-
tion, and normal physiologic and behavioral functioning. For instance,
as will be described below, nicotine may produce a small, but important,
enhancement of work performance. These effects appear to be mediated
by the effects of nicotine on hormonal release and regulation The
following is a brief summary of some of the effects of nicotine, con-
sidered therapeutic by tobacco users, that have been investigated.

Several studies have shown that nicotine enhances performance on a
variety of cognitive tasks that involve speed, reaction time, vigilance,
and concentration (5265). These effects are strongest in cigarette
smokers who are deprived of cigarettes. However, such performance
enhancement was also evident after the administration of nicotine to
nonsmokers and was produced by increasing the nicotine dose in per-
sons who were already smoking. Nicotine may also be a useful mood
regulator by virtue of its release of norepinephrine from the adrenal
medulla (56). Norepinephrine release is also stimulated by excitement,
exercise, sex, antidepressant drugs, and other drugs of abuse, sug-
gesting that cigarette smoking may function pharmacologicalIy to
alleviate boredom and stress. Finally, as an anoretic (57+X?), nicotine ap-
pears to function in three ways: by decreasing the efficiency with which
food is metabolized (61,62); by reducing the appetite for foods that con-
tain simple carbohydrates (sweets) (63); and by reducing the eating that
may occur in times of stress (64). Nicotine may also function as an am&
lytic by reducing responsiveness to stressful stimuli and enhancing
mood (56). In addition, nicotine reduces aggressive responses in experi-
mental situations (65).

A well-documented therapeutic role for nicotine as a drug is evident in
the treatment of tobacco abstinence for many individuals following
dependent patterns of tobacco use, e.g., as assessed by the Fagerstrom
Tolerance Questionnaire (25). This test provides both scientific and prac-
tical evidence of the role of nicotine in tobacco dependence. It is well

154


established that abstinence from tobacco in heavy cigarette smokers
produces signs and symptoms of rebound that can be reversed by
resumed tobacco use and at least partially reversed by other forms of
nicotine administration (66). For example, nicotine gum treatment for
cigarette smoking is efficacious, although a variety of factors limit suc-
cess rates &I).* This drug substitution strategy is analogous to those
obtained when intravenous opioid users are treated with other opioids
given via other routes. For example, methadone administration may
reverse signs and symptoms of opioid withdrawal, while leaving the pa-
tient feeling partially treated yet likely to relapse if not provided with
an adjunctive behavioral treatment (67).

Although the euphoriant properties of drugs can stand apart from
collateral therapeutic actions (as is the case with morphine, am-
phetamine, and alcohol), attention to such drug effects may enhance the
efficacy of treatment. Because nicotine, in the form of tobacco, is widely
available, is relatively inexpensive, and is in a convenient form for
precise dose regulation, it provides an ideal means of self-medication.
These effects may contribute to the abuse liability of tobacco and are of
demonstrable significance in the treatment of tobacco addiction (51).

Sii Strategies Are Involved in the lkeatment of
Tobacco Addiction and Other Forms of Drug Addiction

If tobacco use is a form of drug addiction, then strategies of treat-
ment of other forms of drug addiction should be applicable. Most avail-
able information and existing strategies for treatments of tobacco use
are based on nonpharmacologic approaches. Such approaches have
been no more useful in the treatment of tobacco dependence than in the
treatment of dependence of opioids, stimulants, sedatives, or alcohol.
On the contrary, experience in the treatment of drug addiction
disorders makes clear the importance of addressing the pharmacologic
components of the addiction (67). This conclusion is strengthened by the
observation that persons being treated for opioid addiction regard
tobacco to be as necessary as methadone (68) and that persons success-
fully treated for other kinds of drug addiction are unable to give up
tobacco (ss/. This provides the support for the fundamental premise
that tobacco addiction generally constitutes an independent health-
impairing disorder. Specific treatment implications relating to cigarette
smoking as a form of drug abuse are considered below.

`lb the extent that tobacco use is similar to other forms of drug abuse,
treatment strategies that are used for drug abusers may be applied to
the treatment of cigarette smoking. Although it is not the purpose of
this chapter to describe in detail the treatment for cigarette smoking, a

o These therapeutic effects are produced by nicotine chewing gum. an orally administered form of nicotine that is
approved by the Food and Dru
         J Administration (FDA). The
tmn only and is commonly u          .r m is obtainable in the United States by prescrip
               by physicians to help indiw uals quit smoking.

155


few commonalities, as well as differences, are worth mentioning. Four
basic pharmacologic treatments for drug abuse provide the advantage
of licit administration of an agent controlled by a certified clinician
These involve substitution therapy (e.g., methadone for opiate depen-
dence) in which a more manageable form of the drug is provided accord-
ing to a prearranged maintenance protocol; blockade therapy (e.g.,
naltrexone for opiate dependence) in which the effects of the abused
drug are blocked by pretreatment with an antagonist; and nonspecific
supportive therapy in which the patient is treated symptomatically, ex-
emplified by the temporary use of bemodiazepines during alcohol
detoxification (67). All three approaches have been used in the treat-
ment of cigarette smoking with varying degrees of success (48). A
fourth strategy of pretreating the patient with a drug that results in
adverse side effects when the subsequent abused drug is taken (e.g.,
treatment of alcoholism with disuhiram) has not been systematically
explored with tobacco.
The most recent, widely used treatment for cigarette smoking, and
the first of those recognized as efficacious by the FDA, is modeled
directly after the treatment of heroin addiction by methadone substitu-
tion. This treatment is nicotine gum substitution 170). It is a practical
application of the postulate that tobacco use is basically a form of drug
addiction on nicotine. This recognition is especially relevant here,
because smokeless tobacco is an oral form of nicotine. All of the relevant
therapeutic data support the premise that compulsive tobacco use en-
tails nicotine addiction, which in the form of tobacco exposes the user to
health hazards, and that therapeutic strategies paralleling those for
other forms of drug abuse are effective in treatment. Differences appear
to be principally related to the social tolerance of tobacco addiction,
relative to other forms of drug addiction, which contribute to greater
difficulty in treating this form of drug abuse.

Summary of Commonalities Between Tobacco and
Prototypic Addictive Drugs
The preceding review has shown that tobacco shares many points in
common with prototypic addictive drugs. These similarities provide a
strong conceptual basis for the categorization of tobacco as an addictive
drug. The behavioral process is orderly, tobacco self-administration
results in the delivery of a centrally active drug (nicotine), and the drug
appears to be the major dete rminant in the control of the compulsive
behavior of tobacco self-administration These findings are consistent
with those expected with animal and human subjects, as determined
across a broad range of studies of drugs of abuse (.).

In summary, tobacco, opium, and coca produce different effects but
share a number of important similarities. Whereas large doses of
opioids can produce a debilitating sedation, high doses of coca alkaloids
(cocaine HCI) produce levels of behavioral excitation that are not nor-

156


mally produced by tobacco; but the intake of all of these substances
leads to compulsive use. Compulsive use and the other commonalities
described in the preceding subsections provide compelling evidence
that tobacco use can be a form of drug dependence or addiction. The
next major question is what element(s) of tobacco are critical to control-
ling the behavior of the user. The conceptual leap from habitual
behavior to drug abuse and addiction can be made only on the basis of
evidence that a specific psychoactive drug is critical to the behavior.
The next section on the abuse liability and dependence potential of
nicotine will address this question.

Experimental Studies of the Abuse Liability and
Physical Dependence Potential of Nicotine

The comparison of tobacco to prototypic addictive drugs is the basis
for concluding that compulsive tobacco use is a form of drug
dependence behavior in which nicotine plays an important role. `lb test
this hypothesis further, it should be possible to show that nicotine is an
abusable substance even in the absence of the many stimuli associated
with cigarette smoking. This can be done by evaluating nicotine in ac-
cordance with methods and criteria that have been used to assess any
substance that is suspected of causing abuse and physical dependence.
Onehalf century of research at the NIDA Addiction Research Center,
and research in other laboratories, has produced valid and reliable ex-
perimental methods to evaluate a substance's potential to cause abuse
and to produce physical dependence. The methods are empirically based
on generally accepted examples of drug addiction, most notably opioid
dependence (e.g., morphine) and, to a lesser degree, psychomotor
stimulant dependence (e.g., cocaine) and sedative dependence (e.g., bar-
biturates and alcohol). These methods encompass standards for assess-
ing the two dimensions of drug addiction-abuse liability and physical
dependence potential. The evidence that is related to the abuse liability
and physical dependence potential of nicotine is presented below.

Abuse Liability of Nicotine

Abuse liability refers to drug effects that contribute to compulsive
self-administration, often in the face of excessive financial cost, physical
and social dysfunction, and the exclusion of more socially acceptable
behaviors (S,S). In other words, it entails those effects of a substance
that contribute to diminution of voluntary control over the use of the
substance by the individual.
Objective methods to assess abuse liability are available and have
been used to assess diverse agents 1'). These methods have been readily
adapted to studies of nicotine abuse liability, with consideration given
to the fact that nicotine has more rapid effects than many other drugs of
abuse.

157


The hypothesis is that nicotine is psychoactive and serves as a
euphoriant and reinforcer. Psychoactivity and euphoria are determined
by assessing the pharmacodynamic subjective effects of single doses of
the drug ("singledose" or "abuse liability" studies) and are validated
by observed behavioral and physiologic responses. Reinforcing efficacy
is determined by assessing the ability of the drug to strengthen and
maintain orderly patterns of behavior when the subject is permitted ac-
cess to the drug (i.e., the prototypic "self-administration" study).

Phxunuzcodynamic Effects of Nicotine. In human studies of nicotine
related psychoactivity, volunteers are given a range of doses of the test
compound and placebo under doubleblind conditions. Persons with
histories of drug abuse are used because they can accurately disuiminate
compounds with a potential for abuse and can compare the effects of the
compounds to those of abuse drugs (5). In one study, three doses of
nicotine were given both intravenously and in the form of tobacco smoke
under controlled conditions (71). Nicotine produced a similar profile of ef-
fects (figure 1). Self-reported (subjective), observer-reported (behavioral),
and physiologic variables were measured before, during, and after drug
administration In brief, nicotine was shown to be psychoactive, as
evidenced by the reliable disc rimination of nicotine from placebo, Self-
reported effects of nicotine peaked within 1 minute after administration
(by either route) and dissipated within a few minutes: peak and duration
of response were directly related to the dose.

The two hallmark indicators of euphoria in such studies are the Lik-
ing Scale (Single Dose Questionnaire) and the Morphine Benzedrine
Group (MBG) Scale (Addiction Research Center Inventory [ARCI]) (5).
Responses on the 5-point Liking Scale, which asked how much the drug
was liked (0 = "not at all," 4 = "an awful lot") are presented in figure 2.
Nicotine produced responses on the Liking Scale similar to those of
morphine and d-amphetamine. MBG Scale scores of the ARC1 were con-
sistent with the Liking Scale data, confirming that nicotine, given by
both routes of administration, was a euphoriant. In another comparison
between drugs, subjects more frequently identified nicotine injections
as cocaine.

Similar results for intravenous and inhaled nicotine were also obtained
on several physiologic measures, including pupil diameter, blood
pressure, and skin temperature. These data confirmed that nicotine,
given in either tobacco smoke or intravenously, was the critical pharma-
cologic compound accounting for these effects of tobacco smoke. A sub-
sequent study showed that nicotine's subjective and physiologic effects
could be partially blocked by pretreating the subjects with the antago-
nist mecamylamine (18). Results of studies with animals also indicate
that nicotine produces discriminable effects, and the data suggest that
animals identify nicotine as being more similar to cocaine than to
placebo or pentobarbital, but not identical to cocaine (17).

158


FIGURE l.-This figure is a summary of the data from a study of the
liability of nicotine delivered as tobacco smoke (filled symbols-IN or
intravenous injections (open symbols-IV). Dose is presented on the hori-
zontal axes. Even with a controlled smoking procedure, nicotine dose
administration via cigarette smoke is more variable (producing flatter
doseresponse functions) than when given intravenously. Also, important
effects of nicotine are covert though reliable and orderly (e.g., relaxed feel-
ings, symptom scores). The finding that a low dose of tobacco smoke was
more effective in reducing desire to smoke than a low dose of intravenous
nicotine is consistent with the fact that satisfaction from smoking is also
due to stimuli provided by the cigarette and the smoke.

Self-Administration ofNicotine. The second abuse liability dimension
uses the "self-administration" procedure to examine the conditions
under which a subject will voluntarily take the drug. Self-administration
studies determine whether the drug serves as a biologically effective,
positive reinforcer (or reward). Variants of these strategies are con-
ducted in both animal and human subjects, thereby providing a means
of establishing the biologic generality of the phenomena, while control-
ling the possible confounding influence of personality, social, or cultural
variables. A high degree of concordance between findings from animal


FIGURE Z.-This figure presents data from a series of abuse liability
studies conducted at the Addiction Rezxmch Center. The rmdings that
Liking Scale scores are directly related to dose and exceed placebo
values are important in identifying dependenceproducing drugs. Intra-
venous nicotine produced the same elevated dose-response function as
highly addictive narcotics (e.g., morphine) and a prototypic stimulant
(d-amphetamine). These data are also consistent with the lower abuse
liability of chlordiazepoxide and almost negligible abuse liability of
zomepirac. Administration of intravenous cocaine results in a function
similar to that shown for intravenous nicotine, except that the cocaine
dose levels must be increased by a factor of 5 to 10.

  MORPHINE
   (SC)
2
t /

::    P 7.5 IS 30

W

a
z 2  PENTOBARBITAL

a
W
= I   o

P    120   240

BUPRENORPHINE
  (SL)
/




0
1
P

P  .75 I.5 3

CHLORDIAZEPOXIDE
    (PO)

0 4



I    1 1 I
P   50 100 200

DRUG DOSE (mgl

PENTAZOCINE
(lrn)   P:T

t A-9-THC
  (PO)

t:
P 5   IO 20

ZOYEPIRAC
  (PO)

P 200 400 800

and human studies has been established over a wide range of drugs (20).
Therefore, this section focuses on the results of studies using human
volunteers.
The methods developed in animal studies can be used to assess
whether the pharmacologic activity of a drug maintains self-administra-

160


FIGURE 3.-This figure shows the patterns of nicotine self-
administration that occurred when volunteer cigarette smokers were
given the opportunity to take injections of nicotine, but not smoke
cigarettes, during 3-hour tests. The amount of nicotine available was
roughly comparable to that obtained by smoking cigarettes. The sub
jects smoked less following sessions in which they took nicotine than
following sessions in which only saline (the placebo) was available.

I.V. NICOTINE INJECTIONS

SUBJECT                               &!/kg

BE I    I        I     I I    I         I         I      27

KOI I         I            I               I      I    27

SKw I       I          I          I         I        L22

KUI I      I I I    II III        I I    I     11 I22

PEw I 11 I I     I             I II I II II I     I I   18

LA1 I I I I I I I I I I I I I    II I   II I I I II 18

KE 11 111 11 1 I I I 1     II I I I I I I II I   11 1 13

-3   HOURS-I

tion paralleling drug seeking and drug taking by individuals in the
natural environment or "real world." The strategy is particularly useful
in studies of nicotine, because it precludes confounding by other stimuli
that are associated with tobacco smoke inhalation (e.g., the tobacco
brand, smell of the smoke, and lighting-up rituals).

In one such study, tobaccodeprived volunteers were tested during
3-hour sessions in which 90 presses on a lever resulted in either a nice
tine or placebo injection (72). All six subject% voluntarily self-
administered nicotine (figure 3). Patterns of self-administration (injec-
tions) were similar to those observed when human subjects smoke
cigarettes and when rhesus monkeys take intravenous amphetamine in-
jections in comparable experimental situations (20).

One subject, who lacked a history of drug abuse, exhibited an acquisi-
tion pattern of nicotine self-administration that developed gradually
over several sessions. The pattern was a prototypic example of drug

161


abuse development. Doubleblind substitution of saline for nicotine
resulted in cessation of the self-injection behavior of subject KO (figure
3). Subjects who were given access to both nicotine and placebo concur-
rently (by pressing alternate levers) chose nicotine, confirm@ that
nicotine had come to serve as a positive reinforcer (73). These data indi-
cate that the pharmacologic activity of nicotine was critical to the
maintenance of the behavior.

Nicotine self-administration has been studied in a variety of non-
human species under a variety of experimental conditions (74). As noted
earlier, recent results confirm that nicotine can function as an effective
reinforcer although the conditions under which it serves as a reinforcer
for animals are more restricted than those for morphine or cocaine (21).
Nicotine self-administration via cigarette smoke or smokeless tobacco
may provide ideal confluences of conditions for the establishment and
maintenance of nicotine dependence in humans (33) with the presence of
immediate and abundant peripheral taste and olfactory stimuli (75).

Implications of Pharmucodynamic and Self-Administration Studies.
The results of the pharmacodynamic and self-administration studies
provide direct evidence that nicotine itself, and apart from its beii pre
sented in combination with all of the orosensory properties of tobacco
smoke, is an abusable drug. That is, nicotine meets the criteria of being
psychoactive: it serves as a euphoriant and as a reinforcer. These find-
ings strongly suggest that nicotine parallels other drugs (e.g., morphine
in opium use, cocaine in coca leaf use, and ethanol in alcoholic beverage
consumption) in its ability to maintain self-administration. The find-
ings are of sufficient strength that the relevant public health implica-
tions have already been incorporated into issues of public health policy
by the former Director of the National Institute on Drug Abuse, Dr. W.
Pollin (76), the U.S. Public Health Service (77), and the former Secretary
of the Department of Health and Human Services, Mrs. M. Heckler (78).

Physical Dependence Potential of Nicotine

Physical dependence potential (also referred to as physiological
dependence potential) pertains to the direct physiologic effects that are
produced by the repeated administration of a drug that results in neuro
adaptation (3,4). Neuroadaptation is characterized by demonstrated
tolerance to the effects of the drug and the occurrence of physiologic
withdrawal signs following the termination of drug administration.

Physical dependence potential studies are conducted according to
standardized tests, using methods such as the substitution approach in
which an active drug is removed and replaced with either a placebo or
another form of the drug (5). Although many studies on the effects of
tobacco abstinence on mood, behavior, and physiologic functions have
been conducted, until recently, the classic "direct addiction" or
"substitution" methodologies had not been used to study the physical
dependence potential of nicotine (79).

162


The absence of such studies and the fact that many critical markers of
tobacco abstinence are not overt or easily measured (e.g., change in
affect, EEG, and cognitive performance impairment) have led to ques-
tions about the severity of the tobacco withdrawal syndrome (33).
However, as shown below, abstinence from chronic tobacco or oral nice
tine use is followed by a syndrome of behavioral and physiologic
changes that are orderly, replicable, specific to nicotine, and of func-
tional consequence in relapse to tobacco following abstinence. The
apparent absence of withdrawal symptoms among some people is not
inconsistent with the finding that nicotine has the potential to produce
physical dependence. As is true for users of opiates (e.g., heroin), the
magnitude of the withdrawal syndrome is related to a variety of factors
such as dosage and individual predispositions (80).
Definition of lbbacco Withdrawal There are abundant data indicat-
ing neuroadaptation to tobacco use, showing that this adaptation is at
least partially nicotine specific and that termination of chronic tobacco
use produces a behavioral and physiologic rebound or withdrawal syn-
drome (33). This has been stated in the Diagnostic and Statistical
Manual (DSM) of the American Psychiatric Association (APA) as
follows (81):

Tobacco Withdrawal (APA, DSM, III, 1980). The essential feature
is a characteristic withdrawal syndrome due to recent cessation of or
reduction in tobacco use that has been at least moderate in duration
and amount. The syndrome includes craving for tobacco, irritability,
anxiety, difficulty concentrating, restlessness, headache, drowsiness,
and gastrointestinal disturbances. It is assumed that this syndrome
is caused by nicotine withdrawal, since nicotine is the major pharma-
cologically active ingredient in tobacco.

Withdrawal does not occur with all smokers; but in many heavy
cigarette smokers, changes in mood and performance that are prob
ably related to withdrawal can be detected within two hours after the
last cigarette. The sense of craving appears to reach a peak within the
first 24 hours after the last cigarette, thereafter gradually declining
over a few days to several weeks. In any given case it is difficult to dis-
tinguish between a withdrawal effect and the emergence of pychologi-
cal traits that were suppressed, controlled, or altered by the effects of
nicotine.

This definition by the American Psychiatric Association represents a
reasonable consensus from various reviews of the literature on cigarette
smoking and physiologic dependence on tobacco (3,13,32,82&3). It is
based on experimental data and clinical observations from cigarette
smoking treatment studies demonstrating that certain signs and symp-
toms are of unusualIy high prevalence during the first few days of absti-
nence. Decreased heart rate and blood pressure have been studied
experimentally (84), as well as changes in cortical EEG potentials (85,86,),

163


changes in urine catecholamine excretion (83, and weight gain (57).
Other possible concomitants of tobacco withdrawal reported clinically
include headaches, gastrointestinal disturbances, insomnia, and fatigue
(82,87). A variety of behavioral effects occurs when tobacco or nicotine
administration is abruptly Wmina ted in human and animal subjects,
including increased irritability, aggressiveness, and anxiety; perfor-
mance also is impaired in various psychomotor and learning tests such
as simulated driving, vigilance, and paired-associate learning (88-W).
Self-reported desire to smoke cigarettes ("craving") increases sharply for
about 1 day following abstinence, then gradually declines over the course
of about 1 week to a lesser level (91). Most of these signs and symptoms of
withdrawal subside over 1 to 2 weebs; however, some former tobacco
users report that the desire to smoke may recur for many years and may
be evoked by specific environmental stimuli that were previously
associated with smoking, such as after meals or in selected social situa-
tions. This, too, parallels the powerful conditioning phenomena that are
reported to be associated with other drugs of abuse (92).

Evidence of lbbacco Withdrawal Symptoms. There is compehing evi-
dence that acute tobacco abstinence produces a rebound (withdrawal)
syndrome. This evidence comes from studies of two laboratories in which
increases in low-i?equency EEG bands and decreases in cortical activity
were observed during the first day of tobacco abstinence (&QX$. These
effects were immediately reversed when the subjects were allowed to
smoke two cigarettes.
In a study of self-reported withdrawal symptomatology, 40 partici-
pants completed four 25&m questionnaire forms daily for 2 weeks (93).
Subjects were divided into two groups: totally abstinent and partiaky
abstinent whose smoking levels were maintained at an average of 60 per-
cent. Four symptom clusters emerged: (1) drowsiness in both groups
declined over the first week and then increased over the second week,
forming a U-shaped function; (2) physical symptoms (e.g., headaches and
gastrointestinal disturbances) in both groups declined rapidly the first
week and then remained stable across the second week; (3) psychological
symptoms (e.g., anxiety and irritability) in both groups paralleled physi-
cal symptoms; and (4) craving symptoms in the totally abstinent group
closely paralleled physical and psychological symptoms, whereas craving
levels of the partially abstinent subjects remained elevated across the 2
weeks. The finding that partial abstinence is accompanied by persistent
craving symptomatology is similar to the results of studies on the treat-
ment of illicit opioid dependence with methadone. In these studies, low-
dose methadone maintenance is associated with a persistent opioid crav-
ing (94).
An important series of studies on the dependence potential of nicotine
has recently been completed at the University of Minnesota (95,%$97).
The goals of these studies were to determine reliable and valid indicators

164


of tobacco withdrawal by examining physical, subjective, and behav-
ioral reactions to tobacco deprivation. The first three studies of this
series evaluated the dependence potential of tobacco and established a
reliable battery of measures. In a residential study, 27 smokers resided
for 7 days on a research ward ($5). Following baseline, they were assigned
to abstain from smoking or to continue smoking for 4 days. Physiologic,
subjective, and behavioral measures were obtained and analyzed. The
second study was conducted on a nonresidential basis to assess tobacco
withdrawal in the nonlaboratory environment (W. In this study, signs
and symptoms of tobacco withdrawal were measured in 100 smokers.
Following baseline measurements, subjects were randomly assigned to
either nicotine or placebo gum, to be chewed at each subject's own rate.
The subjects returned on three different occasions for assessment. The
third study assessed the reliability of the tobacco withdrawal syndrome
within subjects ($7). This study employed a modified, within-subject ex-
perimental design; baseline smoking, tobacco deprivation, return to
baseline smoking, and tobacco deprivation were assessed in each sub-
ject.

The results of all three studies demonstrated that the syndrome of
withdrawal that occurs reliably and consistently in chronic smokers
after tobacco deprivation includes decreased heart rate, increased
caloric intake/eating, an increased number of awakenings during sleep,
an increased desire to smoke cigarettes, and increased confusion. Other
changes that were found, but not consistently, included increased irri-
tability and decreased vigor. A prospective examination of data from
both residential and nonresidential studies revealed that there were no
statisticahy significant differences between men and women in either
number or severity of tobacco withdrawal symptoms (98.

A subsequent study was designed to assess the relationship between
tobacco withdrawal symptoms and pre and post-cigarette blood nice
tine levels, prec&arette cotinine levels, change in nicotine level from
pre to post-cigarette, half-life of nicotine, and total smoke exposure ($9).
Twenty subjects were required to smoke cigarettes for 3 days using a
portable recorder that allowed measurements of smoking topography
in a nonlaboratory environment. Blood samples were drawn to deter-
mine blood nicotine and cotinine levels. Subjects abstained from
cigarettes for the next 4 days. A battery of tests to measure tobacco
withdrawal symptoms was administered. In general, results showed an
inconsistent relationship between measures of nicotine intake and
tobacco withdrawal. The most consistent finding was the relationship
of the desire to smoke cigarettes to blood nicotine and cotinine levels
and change in nicotine from pre and post-cigarette; that is, the higher
the nicotine and cotinine level and "nicotine boost," the greater the
desire for cigarettes during abstinence.
The three initial studies that were conducted at the University of
Minnesota (95,,9697) systematically examined the physiologic depen-

165


dence produced by chronic tobacco use. This work represents a major
advance in furthering the understanding of tobacco dependence. The
NIDA Addiction Research Center is also nearing the completion of a
series of studies on the physical dependence potential of tobacco and
the degree to which oral nicotine treats the abstinence syndrome. F're-
liminary data analysis confirms the findings from the Minnesota
studies.

Implications of Physical Dependence Potential Studies. These recent
studies confirm and extend the findings of earlier investigations that
demonstrated that nicotine had the potential to produce. physiologic
dependence. It is now known that the syndrome is orderly and is due to
the administration and withdrawal of nicotine. The overt signs are more
subtle than those marking opioid and sedative withdrawal, but these
signs are not necessarily less important to the individual For instance,
withdrawal effects such as mood changes, performance deficits, and
weight gain may be of considerable importance to the normal function-
ing of the individual. It is anticipated that just as detoxification and
treatment of opioid and sedative dependence have benefited from im-
proved understanding of these syndromes of withdrawal, so also may
detoxification and treatment of tobacco withdrawal benefit.

Evidence That Orally Delivered Nicotine (Including
Via Smokeless Tobacco) Has a Liability for Abuse and a
Potential to Produce Physical Dependence

As previously indicated, moist snuff contains as much as 15.1 mg
nicotine per gram; plug tobacco contains 17.2 mg per gram (100,101).
Lower-nicotinecontaining brands exist. However, marketing efforts
encourage (and users demonstrate) graduation to the higher-nicotine
containing products (1). These levels of nicotine are substantial, since
the relative potency of nicotine is 5 to 10 times greater than that of co
caine in producing di suiminable subjective effects (1 to 2 mg of nicotine
given intravenously, orally, or inhaled produces reliable behavioral and
physiologic effects).
`Ityo studies have confirmed that typical patterns of smokeless tobac-
co use result in the delivery of quantities of nicotine that produce
plasma nicotine elevations comparable to those produced when ciga-
rettes are smoked (102,1031. These studies also found that smokeless
tobacco use reflected several of the indices of abuse liability and
physical dependence potential. Smokeless tobacco users self-
administered substantial quantities of nicotine; the patterns of
smokeless tobacco use were orderly and stable; and subjective and
behavioral effects may be produced from such use. More recently, a new
form of smokeless tobacco, moist brown tobacco in tea bag-like
pouches, was also shown to deliver pharmacologically active quantities
of nicotine to the central nervous system (104).

166


Reinforcing Properties of Nicotine in the Form of Chewing Gum
There is growing evidence that nicotine is reinforcing and has the
potential to produce dependence even when absorbed through the buc-
cal mucosa (and therefore more slowly) via chewing gum (nicotine pola-
crilex). One recently completed study involved the self-administration
of either a nicotine or placebo-containing chewing gum by smokers who
had quit smoking (105). When given a choice between placebo and
nicotine chewing gum, subjects preferred nicotine to placebo and self-
administered the nicotine gum throughout each day.* These data are
particularly compelling, because nicotine, in the form of the nicotine
polacrilex, is in an ion-bound complex. In this preparation, the nicotine
is released and absorbed slowly compared to the nicotine in smokeless
tobacco; and the polacrilex form of nicotine administration appears to
be of relatively low abuse liability. This study also demonstrated that
instructions by a physician can alter patterns of gum use and preference
(105). These data, which suggest that instructions can modulate the self-
administration of orally delivered nicotine, are in keeping with the well-
known fact that physicians control their patients' use of narcotics,
sedatives, and stimulants.

Physical Dependence Potential of Smokeless Tobacco

Hatsukami and coworkers, at the University of Minnesota, studied
neuroadaptation (physiologic dependence) in smokeless tobacco users
(10s). All 16 subjects in the study used moist snuff and no other
nicotine-delivering product. Measures of mood, feeling, behavior, and
physiologic function were cornpar& 1.t baseline and during abstinence.
Subjects showed significant signs and symptoms of nicotine with-
drawal as measured by decreased resting pulse, attenuated orthostatic
pulse changes, and increases in tobacco seeking ("craving"), eating,
sleep disruptions, and confusion.
A study with nicotine g-urn showed orally delivered nicotine may
cause physical dependence (107). The subjects that were tested had been
treated for tobacco dependence with nicotine gum that they used on a
daily basis for at least 1 month. Eight subjects were then tested over
the course of 4 weeks. They were given nicotine-containing gum during
the first and fourth weeks; during the second and third weeks, they
received nicotine gum for 1 week and placebo gum for the other. During
the week that placebo gum was presented, seven subjects showed signs
and symptoms of withdrawal, and two subjects relapsed to smoking or
nicotine-containing gum. This study confirms that oralIy given nicotine
has the potential to produce physical dependence. These findings were
most recently confirmed by another study that showed development of
physical dependence to nicotine gum in patients treated for tobacco
dependence (1 Ch9).

* Selfadmimstratron rook place ar an average raw of 7 4 pieces compared to an average of 1.2 paces of placebo
gum per day.

167


References

(1) ConnoIIy, G.N.. Winn, D.M., Hecht, S.S.. Henningfield, J.E., Hoffmann,
D., and Walker, B. Science public policy and the reemergence of smoke
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PHYSIOLOGIC AND PATHOGENIC EFFECTS OF
NICOTINE AND SMOKELESS TOBACCO

The user of smokeless tobacco is systematically exposed to signifi-
cant amounts of nicotine, a potent multisystem pharmacologic agent.
This chapter addresses the physiologic effects of nicotine upon the car-
diovascular, nervous, and endocrine systems and the possible roles of
nicotine in the pathogenesis of a variety of diseases.

Nicotine is described in pharmacology textbooks as a stimulant of
autonomic ganglia and skeletal neuromuscular junctions (i.e., nicotinic
muscarinic receptors). However, in vivo the actions of nicotine are far
more complex depending on the dose, target organ, prevalent auto
nomic tone, and previous exposure history (tolerance) (1,Z). For pur-
poses of this review, the focus is on the effects of nicotine in humans.
Where human data are lacking and animal studies provide important
information about physiologic effects, those studies are also discussed.

Most data on the actions of nicotine in humans derive from studies of
the effects of cigarette smoking, comparing cigarettes with and without
nicotine, and studies of the effects of intravenous nicotine. These
studies provide the basis for our understanding of the human pharma-
cology of nicotine. However, as noted previously, actions of nicotine
from smokeless tobacco and nicotine via inhalation or intravenous infu-
sion may differ.

Physiologic Effects of Nicotine

Cardiovascular System

The predominant cardiovascular actions of nicotine result from ac-
tivation of the sympathetic nervous system. Smoking a cigarette in-
creases the heart rate (10 to 20 BPM), blood pressure (5 to 10 mmHg),
cardiac stroke volume and output, and coronary blood flow (34). Smok-
ing may have different effects in smokers with coronary heart disease.
It may reduce left ventricular contractility and cardiac output (6), ef-
fects that are believed to be related to myocardial ischemia due to
smoking-mediated tachycardia and the effects of carbon monoxide.
Coronary blood flow may also decrease after smoking, which possibly is
related to a nicotinemediated increase in coronary vascular resistance
(7,8). Smoking, or nicotine intake, causes cutaneous vasoconstriction
that is associated with a decrease in skin temperature, systemic veno-
constriction, and increased muscle blood flow (411).

Smoking results in increased circulating concentrations of norepi-
nephrine, consistent with neural adrenergic stimulation, and epinephrine,
indicating adrenal medullary stimulation (3). Circulating free fatty
acids, glycerol, and lactate concentrations increase. Cardiovascular and
metabolic effects are prevented by combined alpha and beta adrenergic
blockade, which indicates that the cardiovascular effects of cigarette
smoking are mediated by activation of the sympathetic nervous

175


system. Smoking-induced reduction in skin blood flow also can be
antagonized by a vascular vasopressin antagonist, which suggests a
role for vasopressin in mediating some cardiovascular responses (2).

The cardiovascular effects of oral snuff have been examined system-
atically in only one study (13). Changes in heart rate and blood pressure
that are similar in magnitude to those of cigarette smoking were ob
served. However, the time course appears to be slower than the
response to cigarette smoking, with maximum effects observed at 5 to
10 minutes after a dose of oral tobacco. Similar findings, along with in-
creased myocardial contractility and coronary, femoral, and renal blood
flow, were also noted in anesthetized dogs after the administration of
oral tobacco (13). Thus it appears that single doses of smokeless tobac-
co can produce hemodynamic effects that are similar to those of
cigarette smoking. Whether such changes are sustained throughout the
day with repeated daily doses remains to be established.

Central Nervous System

Although smokers give different explanations for why they smoke,
most agree that smoking produces arousal, particularly with the first
few cigarettes of the day, as well as relaxation, especially in stressful
situations (14). Desynchronization, decreased alpha and theta activity,
and increased alpha frequency that is consistent with arousal are the
usual electroencephalographic responses to cigarette smoking (X,16).
These effects are blocked by mecamylamine, a centrally active nicotinic
receptor antagonist, which indicates a role for nicotinic cholinergic
receptor activation I1 7). Tobacco abstinence is associated with effects
that are opposite those of smoking, namely, increased alpha power and
reduced alpha frequency (15,18).

Endocrine System

Cigarette smoking and nicotine have been reported to increase circu-
lating levels of catecholamines, vasopressin, growth hormone, cortisol,
ACTH, and endorphins (3,19,20).

Nicotine inhibits the synthesis of prostacyclin in rabbit aorta and
human peripheral veins and the hypoxia-induced release of prostacyclin
from rabbit hearts (21). Cigarette smoking has been reported to decrease
the urinary excretion of prostacyclin met&o&s in humans, which sup
ports the prediction from animal studies 122). F'rostacyclin has anti-
aggregatory and vasodilating actions that are believed to play a homeo
static role in preventing vascular thrombosis.

Nicotine, Smokeless Tobacco, and Human Diseases

As attested to in the Surgeon General's reports since 1964, smoking
is a major risk factor for coronary and peripheral vascular disease,
cancer, chronic obstructive lung disease, peptic ulcer disease, and repro

176


ductive disturbances, including prematurity. Tobacco smoke is a com-
plex mixture of chemicals, including carbon monoxide, many of which
are believed to contribute to human disease. Smokeless tobacco
likewise exposes users to a number of chemicals, particularly nicotine.
Nicotine may play a contributory or supportive role in the pathogenesis
of many smoking-related diseases. That nicotine causes human disease
de novo has not been proven; however, its potential health conse
quences deserve serious consideration. More direct data on its causal
role are needed.

Coronary and Peripheral Vascular Disease

Nicotine may contribute to atherosclerotic disease by actions on lipid
metabolism, coagulation, and hemodynamic effects. Compared to non-
smokers, cigarette smokers have elevated levels of low density (LDL)
and very low density lipoproteins (VLDLI and reduced levels of high
density lipoproteins (HDL). This profile is associated with an increased
risk of atherosclerosis (23). It is hypothesized that nicotine, by releasing
free fatty acids, increases the synthesis of triglycerides and VLDL by
the liver, which in turn results in decreased HDL production.
In most studies, the blood of smokers is shown to coagulate more
easily (24), platelets are found to be more reactive, and platelet survival
is shortened when compared to nonsmokers (25,). Thrombosis is believed
to play a role that promotes the growth of vascular endothelial cells that
contribute to the atherosclerotic plaque. The importance of nicotine as a
determinant of platelet hyperreactivity is supported by a study that
shows an apparent relationship between nicotine concentrations after
smoking different brands of cigarettes and platelet aggregation
response (26). Nicotine may affect platelets by releasing epinephrine,
which is known to enhance platelet reactivity; by inhibiting prosta-
cyclin, an antiaggregatory hormone that is secreted by endothelial cells;
or perhaps directly. Finally, by increasing the heart rate and cardiac
output, nicotine increases blood turbulence and may promote endo
thelial injury. Although several potential mechanisms for promoting
atherogenais have been considered, nicotine has not yet been demon-
strated to accelerate atherosclerosis in experimental animals.
Nicotine may play a role in causing acute coronary events. Myocar-
dial infarction can occur with one or more of three precipitants: throm-
bosis, excessive oxygen and substrate demand, and coronary spasm.
Nicotine can promote thrombosis as discussed previously. Nicotine in-
creases the heart rate and blood pressure and, therefore, myocardial ox-
ygen consumption Coronary blood flow increases in a healthy person to
meet the increased demand. In the presence of coronary heart disease,
ischemia may develop and myocardial dysfunction may occur. Nicotine
may induce coronary spasm by sympathomirnetic actions or by the
inhibition of prostacyclin. Coronary spasm has recently been reported
to occur during cigarette smoking (27). All of the above may contribute

177


to the precipitation of acute myocardial infarction in a person with pre
existing coronary atherosclerosis.

Cigarette smoke exposure decreases the ventricular fibrillation
threshold after experimental myocardial infarction in dogs (28). How
much of this effect is due to nicotine and how much is due to carbon
monoxide have not been established. Sudden cardiac death in smokers
might result from ischemia, as discussed above, combined with the
arrhythmogenic effect of increased circulating catecholamines.

Cigarette smoking has not been associated with an increased
prevalence of hypertension. However, a recent preliminary report sug-
gested higher blood pressure in young men who used smokeless tobacco
compared to cigarette smokers or nonsmokers (25% Smokers who have
essential hypertension experience an accelerated progression of
vascular and renal disease. Nicotine may contribute to such a process
by producing vasoconstriction or enhancing coagulation There also
may be other interactions with hypertensive disease. For example, a pa-
tient with a pheochromocytoma developed paroxysmal hypertension
and angina pectoris following the use of oral snuff (Z@). In a controlled
situation, blood pressure was recorded to increase from 110/70 to
300/103 with a heart rate increase from 70 to 110 within 10 minutes
after the use of oral snuff. Rechallenge after surgery for the pheochro
mocytoma revealed only the usual blood pressure increase.

Peptic Ulcer Disease

Smoking is strongly related to the prevalence of peptic ulcer disease,
and failnre to stop smoking is the major predictor of failure to respond
to ulcer therapy (31). Smoking decreases pancreatic fluid and bicar-
bonate secretion that result in greater and more prolonged acidity of
gastric fluid of the duodenal bulb (32). Similar effects after the infusion
of nicotine have been reported in animals (33). The swallowing of tobac-
co juice that contains large concentrations of nicotine may conceivably
have local effects and therefore elicit added concern for the use of
smokeless tobacco.

Smoking is a major risk factor for low birth weight and, conse
quently, fetal morbidity and mortality (34). `Ibbacco smoke may influ-
ence the fetus either through alterations in maternal physiology that
limit the nutrient flow to the fetus or by the transplacental passage of
smoke components that have direct effects on the fetus. The factors
that are considered most likely to affect the fetus are carbon monoxide
and nicotine. Carbon monoxide inhalation has been shown to increase
carboxyhemoglobin in both maternal and fetal blood that possibly
limits oxygen supply to the fetus (35) However, while newborn infants

178


of smoking mothers have higher concentrations of carboxyhemo
globin than do neonates of nonsmokers, there are only trivial differ-
ences in hemoglobin concentrations, hematocrit, and various charac-
teristics of hemoglobin (36). Thus it is difficult to explain an adverse
effect that is based on chronic hypoxia due to carbon monoxide in
tobacco smoke. It is more likely that nicotine is important in causing
adverse effects.

The effects of nicotine on the fetus may include a reduction of uterine
blood flow or a direct effect on fetal function (3738). The presence of
nicotine and its principal metabolites has been demonstrated in the um-
bilical cord blood and urine of newborn infants of smoking mothers, as
well as in amniotic fluid, indicating transplacental passage (39).

Nonnicotine-Related Adverse
Metabolic Consequences

certain brands of chewing tobacco and snuff contain glycyrrhizinic
acid, which is also an ingredient of licorice. Glycyrrhizinic acid has po
tent mineralocorticoid hormone activity that can result in potassium
wasting. `l%ro patients who were heavy users of oral smokeless tobacco
developed severe hypokalemia with muscle weakness (and in one case,
evidence of muscle breakdown) that apparently was due to the ingestion
of large amounts of this substance (40). Smokeless tobacco also contains
large amounts of sodium (41) that, if swallowed, may aggravate hyper-
tension or cardiac failure.

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573-577, 1976.
(4) Irving, D.W., and Yamam oto, T. Cigarette smoking and cardiac out-
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(5) Bargeron, L.M., Ehmke, D., Gonlubol, F., Castellanos, A., Siegel, A.,
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(7) Klein, L.W., Ambrose, J., Pichard, A., Holt, J., Gorlin, R., and
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(8) Reddy. C.V.R.. Khan, R.G., Feit, A., Chowdry, I.H., and El Sherif, N.
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(9) Freund, J., and Ward, C. The acute effect of cigarette smoking on the
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(10) Eckstein, J.W., and Horseley, A.W. Responses of the peripheral veins
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(11) Rottenstein, H., Pence, G., Russ, E.. Felder, D., and Montgomery, H.
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(12) Waeber, G., Schaller, M., Nussberger, J., Bussien, J., Hofbauer, K.G.,
  and Brunner, H.R. Skin blood flow reduction induced by cigarette
  smoking Role of vasopressin. Am. J. Physiol. 247: H895-H901, 1984.
(13) Squires, W.G., Branton, T.A., Zinlcgraf, S., Bonds, D., Hartung, G.H.,
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  195-206, 1984.
(14) Henningfield, J.E. Behavioral pharmacology of cigarette smoking. In:
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  131-210.
(15) Heming, R.I., Jones, R.T., and Bachman, J. EEG changes during
  tobacco withdrawal. Psychophysiology 20: 507-512, 1983.
(16) Knott, V.J., and Venables, P.H. EEG alpha correlates of nonsmokers,
  smokers and smoking deprivation. Psychopharmacology 14: 150-156,
  1977.
(17) Domino, E.F. Behavioral electrophysiological, endocrine, and skeletal
  muscle actions of nicotine and tobacco smoking. In: A. Remond and C.
  Izard (eds.). Electrophysiological Effects of Nicotine. Amsterdam,
  ElsevieriNorth Holland Biomedical Press, 1979, pp. 133-146.
(18) Ulett, J., and Itil, T. Quantitative electroencephalogram in smoking
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(19) Sandberg, H., Roman, L., Zavodnick, J., and Kupers, N. The effect of
  smoking on serum somatotropin, immunoreactive insulin and blood
  glucose levels of young adult males. J. Pharmacol. Exp. Ther. 184:
  787-791, 1973.
(20) Pomerleau, O.F., Fertig, J.B., Seyler, L.E., and Jaffe, J. Neuroendo
  crine reactivity to nicotine in smokers. Psychopharmacology 81: 61-67,
   1983.
(21) Wennmalm, A. Nicotine inhibits hypoxia- and arachidonateinduced
release of prostacyclin-like activity in rabbit hearts. Br. J. Pharmacol.
  69 545-549, 1980.
(22) Nadler, J.L., Velasco, J.S., and Horton, R. Cigarette smoking inhibits
  prostacyclin formation. Lancet 1: 1248-1250, 1983.


(23) Brischetto, C.S., Connor, W.E., Connor, S.L., and Matarazzo, J.D.
  Plasma lipid and lipoprotein profiles of cigarette smokers from ran-
  domly selected families: Enhancement of hyperlipidemia and depres-
  sion of high-density lipoprotein. Am. J. Cardiol. 52: 675-680, 1983.
(24) Bilhmoria, J.D., Pozner, H., Metselaar, B., Best, F.W., and James,
D.C.O. Effect of cigarette smoking on lipids, lipoproteins, blood
coagulation, fibrinolysis and cellular components of human blood.
  Atherosclerosis 21: 61-76, 1975.

(25) Mustard, J.F., and Murphy, E.A. Effect of smoking on blood coagula-
  tion and platelet survival in man. Br. Med. J. 1: 846-849, 1963.
(26) Renaud, S., Blache, D., Dumont, E., Thevenon, C., and Wissendanger,
  T. Platelet function after cigarette smoking in relation to nicotine and
  carbon monoxide. Clin. Pharmacol. Ther. 36: 389-395, 1984.

(27) Maouad, J., Fernandez, F., Barrillon, A., Gerbaux, A., and Gay, J. Dif-
  fuse or segmental narrowing (spasm) of the coronary arteries during
smoking demonstrated on angiography. Am. J. Cardiol. 53 354-355,
  1984.

(`28) Bellet, S., DeGuzman, N.T., Kostis, J.B., Roman, L., and Fleischmann,
  D. The effect of inhalation of cigarette smoke on ventricular fibrillation
  threshold in normal dogs and dogs with acute myocardial infarction.
  Am. Heart J. 83: 67-76, 1976.

(29) Schroeder, K.L., and Chen, M.S. Smokeless tobacco and blood pres-
  sure. N. Engl. J. Med. 312: 919, 1985.

(30) McPhaul, M., Punzi, H.A., Sandy, A., Borganelli, M., Rude, R., and
  Kaplan, N.M. Snuff-induced hypertension in pheochromocytoma.
  JAMA 252: 2860-2862.1984.

(311 Korman, M.G., Shaw, R.G., Hansky, J., Schmidt, G.T., and Stem, A.I.
  Influence of smoking on healing rate of duodenal ulcer in response to
  cimetidine or high-dose antacid. Gastroenterology 80: 1451-1453,198l.
(32) Mm-thy, S.N.S., Dinoso, V.P., Clearfield, H.R., and Chey, W.Y. Simultane
  ous measurement of basal pancreatic, gastric acid secretion, plasma
  gastrin, and secretin during smoking. Gastroenterology 73: 758-761,
  1977.

(33) Konturek, S.J., Dale, J., Jacobson, E.D., and Johnson, L.R. Mecha-
nisms of nicotine-induced inhibition of pancreatic secretion of bicar-
  bonate in the dog. Gastroenterology 62: 425-429, 1972.

(34) Abel, E.L. Smoking during pregnancy: A review of effects on growth
and development of offspring. Hum. Biol. 52: 593-625, 1980.

(35) Longo, L.D. The biological effects of carbon monoxide on the pregnant
  woman, fetus and newborn infant. Am. J. Obstet. Gynecol. l.29: 69,1977.

(36) Bureau, M.A., Shapcott, D., Berthiaume, Y., Monette, J., Blovin, D.,
  Blanchard, P., and Begin, R. A study of P50,2,3diphosphoglycerate,
  total hemoglobin, hematocrit and type F hemoglobin in fetal blood.
  Pediatrics 72: 22, 1984.

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(37) Ayromlooi, J., Desiderio, D., and Tobias, M. Effect of nicotine sulfate
  on the hemodynamics and acid base balance of cbronicaIIy instru-
mented pregnant sheep. Dev. Pharmacol. Ther. 3: 205-213, 1981.
(38) Resnik, R. Brink, G.W., and Wilkes, M. Catecholaminemediatedreduc-
  tion in uterine blood flow after nicotine infusion in the pregnant ewe.
  J. Clin. Invest. 63: 1133-1136, 1979.

(39) Hibberd, A.R., O'Connor, V., and Gorrod, J.W. Detection of nicotine,
  nicotine-l `-N-oxide and cotinine in maternal and fetal body fluids. In:
J.W. Gorrod (ed.). Biological Oxidation of Nitrogen. Amsterdam,
Elsevier, 1978, pp. 353-361.

140) Valeriano, J., Tucker, P., and Kattab, J. An unusual cause of hypoka-
  lemic muscle weakness. Neurology 33: 1242-1243, 1983.
(41) Hampson, N.B. Smokeless is not saltless. N. Engl. J. Med. 31.2: 919,
  1985.

CONCLUSIONS

1. The use of smokeless tobacco products can lead to nicotine
dependence or addiction.

2. An examination of the pharmacokinetics of nicotine (i.e., nico-
tine absorption, distribution, and elimination) resulting from
smoking and smokeless tobacco use indicates that the magni-
tude of nicotine exposure is similar for both.

3. Despite the complexities of tobacco smoke self-administration,
systematic analysis has confirmed that the resulting addiction
is similar to that produced and maintained by other addictive
drugs in both humans and animals. Animals can learn to dis-
criminate nicotine from other substances because of its effects
on the central nervous system. These effects are related to the
dose and rate of administration, as is also the case with other
drugs of abuse.

4. It has been shown that nicotine functions as a reinforcer under a
variety of conditions. It has been confirmed that nicotine can
function in all of the capacities that characterize a drug with a
liability to widespread abuse. Additionally, as is the case with
most other drugs of abuse, nicotine produces effects in the user
that are considered desirable to the user. These effects are
caused by the nicotine and not simply by the vehicle of delivery
(tobacco or tobacco smoke).

5. Nicotine is similar on ah critical measures to prototypic drugs of
abuse such as morphine and cocaine. The methods and criteria
used to establish these similarities are identical to those used for
other drugs suspected of having the potential to produce abuse
and physiologic dependence. Specifically, nicotine is psycho-

182


active, producing transient doserelated changes in mood and
feeling. It is a euphoriant that produces doserelated increases in
scores on standard measures of euphoria. It is a reinforcer lor
reward) in both human and animal intravenous self-administration
paradigms, functioning as do other drugs of abuse. Additionally,
nicotine through smoking produces the same effects, and it
causes neuroadaptation leading to tolerance and physiologic
dependence. l&en together, these results confirm the hypothesis
that the role of nicotine in the compulsive use of tobacco is the
same as the role of morphine in the compulsive use of opium
derivatives or of cocaine in the compulsive use of coca deriva-
tives.

6. The evidence that smokeless tobacco is addicting includes the
pharmacologic role of nicotine dose in regulating tobacco intake;
the commonalities between nicotine and other prototypic
dependenceproducing substances; the abuse liability and depen-
dence potential of nicotine; and the direct, albeit limited at pres-
ent, evidence that orally delivered nicotine retains the character-
istics of an addictive drug.

7. Several other characteristics of tobacco products in general,
including smokeless tobacco, may function to enhance further the
number of persons who are afflicted by nicotine dependence:
nicotine-delivering products are widely available and relatively
inexpensive; and the self-administration of such products is legal,
relatively well tolerated by society, and produces minimal disrup-
tion to cognitive and behavioral performance. Nicotine produces
a variety of individual-specific therapeutic actions such as mood
and performance enhancement; and the brief effects of nicotine
ensure that conditioning occurs, because the behavior is
associated with numerous concomitant environmental stimuli.

8. All commonly marketed and consumed smokeless tobacco prod-
ucts contain substantial quantities of nicotine; the nicotine is
delivered to the central nervous system in addicting quantities
when used in the fashion that each form is commonly used (or as
recommended in smokeless tobacco marketing campaigns).

9. Since the exposure to nicotine from smokeless tobacco is similar
in magnitude to nicotine exposure from cigarette smoking, the
health consequences of smoking that are caused by nicotine also
would be expected to be hazards of smokeless tobacco use. Areas
of particular concern in which nicotine may play a contributory or
supportive role in the pathogenesis of disease include coronary
artery and peripheral vascular disease, hypertension, peptic ulcer
disease, and fetal mortality and morbidity.

183


Available data clearly support the view that nicotine produces behav-
ioral and physiologic dependence and has effects on all critical dimen-
sions exemplified by a drug with a profile of high abuse liability. Never-
theless, the resolution of several questions is essential. These questions
revolve around the relationships between the several forms of tobacco
use. They parallel and have commonalities with important issues in other
forms of drug abuse (e.g., cocaine). There are several major msearch areas
that could provide data of potential public health significance.

The first area of research is the relationship between the rate of nice
tine administration and abuse liability. Existing data suggest that the
slowest commercially available nicotinereleasing preparation, nicotine
gum, has a lower abuse liability than the fastest commercially available
nicotine-releasing ppparation, cigarettes. These facts further suggest
the possibility that there might be quantifiable differences in abuse
liability among tobacco product forms.

The second area of research importance involves the relationship be-
tween the initiation of one form of tobacco use, e.g., smokeless tobacco,
and the use of other forms of tobacco, e.g., cigarettes. The relationships
between common forms of tobacco use, the extent to which they are
interchangeable, and the possibility that the use of one form of tobacco
leads to the use of another need examination.

A third area of specific importance relates to the extent to which
tobacco use, with its implicit acceptance, encourages other drug use. A
related question is the extent to which exposure to drug effects, both
neurologic and behavioral, modifies subsequent drug responses or
establishes the conditions for other equally harmful drugs to become
reinforcers. These issues follow from the observations that cigarette use
is a major correlate (possibly a "stepping stone") of other kinds of drug
dependence and that regular tobacco use generally leads to other forms
of drug addiction.

A fourth area of research is prevention and treatment. Recent sur-
veys indicate that youth attribute negligible risk to smokeless tobacco
products, suggesting the possible need for education-based prevention
approaches. Regarding treatment, it is plausible that nicotine gum
treatment could be of even greater relative utility for smokeless tobacco
users than for cigarette smokers because of the more similar pharmaco
kinetic profiles of smokeless tobacco and gumdelivered nicotine com-
pared to cigarette smoke-delivered nicotine.

The absorption and distribution characteristics of nicotine with the
use of smokeless tobacco may differ from those of cigarette smoking.
The pharmacodynamic and pharmacologic consequences of such dif-
ferences may be important but require additional future research FLU-
ther studies to define more precisely the role of nicotine and of
smokeless tobacco in the causation of diseases other than those that

184


involve the oral cavity are clearly needed. Specifically, research is
needed to:

o Determine nicotine blood levels and time course in various popula-
tions of smokeless tobacco users, including established users.

o Determine the cardiovascular, hormonal, and metabolic effects of
smokeless tobacco when used in a regular fashion throughout the
day.

o Determine the influence of the rate of absorption of nicotine on the
effects from smoking cigarettes and the use of smokeless tobacco.

o Using experimental studies, determine the effects of smokeless
tobacco in users of different ages and high-risk status (i.e., patients
with hypertension, coronary heart disease, peripheral vascular
disease, and peptic ulcer).

o Using epidemiologic studies, determine the risk potential of the
regular use of smokeless tobacco on the development of diseases
such as coronary heart disease, peptic ulcer, and complications of
Pregnancy.

185


INDEX

ABBREVIATIONS
constituents of smokeless
  tobacco, 70
ABRASION (DENTAL)
defined, 128
relation to smokeless tobacco, 130
ABUSE LIABILITY OF
NICOTINE
defined, 145,157
evidence for abuse potential,
  166-167
experimental studies, 157-166
implications of studies, 162
phannacodynamic effects, 158
research needs, 184
self-administration, 159-l 62
ACANTHOSIS
clinical report, 115-118
defined, 113
ADENOCARCINOMA
relation to snuff use, 48
ADOLESCENT USE
attitudes, 24
data criteria, 17
ethnic groups, 20
males vs. females, 20
National Program Inspection
  study, 24
peer and family influences, 24
rural vs. urban areas, 20
ADULT USE
patterns, 16-17
ADVISORY COMMIlTEE TO
THE SURGEON GENERAL,
REPORT
carcinogens revealed, vii
conclusions, vii-viii, xxii
gingival recession, viii
historical perspective of report,
  Xvii-xix
nicotine addiction and effects, viii
noncancerous conditions, xxi
oral leukoplakia. viii
organization of report, xvii
overview, xx-xxii
precancerous oral health
  conditions, xxi
review methods, xix-xx

ALCOHOL CONSUMPTION
relation to smokeless tobacco, 35
ANIMAL MODELS
bioassays with chewing tobacco,
  79, 82-83
bioassays with constituents of
  smokeless tobacco, 86-88
bioassays with snuff, 83-86
metabolism of NMOR, 74-75
metabolism of NNK, 71-73
metabolism of NNN, 73-74
mutagenicity assays, 88-89
pharmacodynamic effects of
  nicotine, 158
physiologic effects of nicotine, 178
sdivmy glands, 126-127
short-term tests, 88-89
ASIAN DATA
case-control studies, 42-43, 119
chewing of quids, 42-43, 50
esophageal neoplasms, 50
rates of oral cancer, 42-43
smokeless tobacco products, 42-43
smoking and oral cancer risk,
  43-44

BIOASSAYS FOR CL4RCTVOGEVIC
Ati'UK'TY OF CZEWiVG
TOBACCO OR tZi%`W;wG
iYm4ccoIiYxmAcr$8o
BIOASSAYS FOR CARClhDGEVIC
ACTNITY OF Sh?UFF OR SNUFF
EXlTUCI$81
BIOASSAYS WITH
CHEWING TOBACCO
(See dso ANIMAL MODELS)
application to the cheek pouch,
  79, 82-83
application to the oral mucosa,
  79, 82-83
oral administration, 79
skin application, 83
subcutaneous application, 83
BJOASSAYS WITH
CONSTITUENTS OF
SMOKELESS TOBACCO
(See also ANIMAL MODELS)
inducement of tumors, 86-88

187


BIOASSAYS WITH SNUFF
(See also ANIMAL MODELS)
application to the lip, oral
mucosa, or cheek pouch, 84-86
oral administration, 83-84
relation to herpes simplex virus,
  86-87
subcutaneous administration, 86
Bladder Neophsms, See URINARY
TRACT NEOPLASMS
Blockade Therapy, See NICOTINE
ADDICTION TREATMENT
BUCCAL CARCINOMA
case studies, 34-36

CALCULUS (DENTAL)
defined, 129
use of smokeless tobacco, 130
CARC~OGHCflY OF TOBACCO
SPECIFIC NITROSAMINES 82
CARCINOGENS
daily exposure from snuff and
chewing tobacco usage, 64
in smokeless tobacco, 58-60. 64-65
N-nitrosamines, 58-60, 64
polonium-210 (21oPo), 58, 65
polynuclear aromatic hydra
  carbons (PAH), 58,65
saliva analysis, 64
CARCINOMA hVSlTU
defined, 114
diagnoses differ, 123
squamous cell carcinoma study,
  120
Cardiovascular System, See
PHYSIOLOGIC EFFECTS OF
NICOTINE
Central Nervous System, See
PHYSIOLOGIC EFFECTS OF
NICOTINE
ChXRACTERLSTICS OF SMOKE
I2239 TOBACCO PRODUCT$6
CHEEK NEOPLASMS
(See also ORAL CANCER)
animal models, 79, 82, 84
case study, 120
CHEMICAL COMPOSITION
processed tobacco, 58
nicotine, 58
CHEMICAL CONSTITUENTS
OF SMOKELESS TOBACCO
carcinogens, 58-59,60,6465
chemical composition, 58

CHEVRON KERATINIZATION
case report, 116-l 17
defined, 114
CHEWING TOBACCO (See also
SMOKELESS TOBACCO,
BIOASSAYS)
case-control studies, 36,40
characteristics, 5
looseleaf, 5,7
plug, 5, 7
twist, 5, 7
CommonaIities Between Tobacco
and Other Addictive Substances,
See NICOTINE ADDICTION
CONCEPTUAL MODEL
of smokeless tobacco lesions, 121
CONCEPTUAL NflVRAL HISTORY
OF ORAL MucosAL CRANGES
ASlSOCiWED WITH TdcE USE OF
SMO- TOBACCO, 122
CORONARY AND PERIPHERAL
VASCULAR DISEASE
acute coronary events, 177-178
and nicotine, 177-178
atherosclerosis, 177
effect on platelets, 177
endothelial injury, 177
research needed, 185
ventricular fibrillation, 178
Cotinine, See PHARMACQ
KINETICS OF NICOTINE

CURRENT POPULATION
SURVEY (CPS)
survey data, 12,14

DATA: ABUSE LUBIUTY .!U'tLVm
AT ADDICTION RESEARCH
CENTER 160
DENTAL CARIES
defined, 128
relation to smokeless tobacco,
  129-130

DOSE RESPONSE EFFECTS
(See also ANIMAL MODELS)
and oral leukoplakia, 13 1
nicotine, 147, 152-153, 158,
  182-183
DRUG DEPENDENCE
commonalities between tobacco

and other substances, 146-147,
152-157
defined, 145
physiologic or physical
dependence, 145-146

188


DYSPLASIA
defined, 114

diagnoses differ, 121. 123
relation to oral lesions, 115-l 16

Endocrine System, See
PHYSIOLOGIC EFFECTS
OF NICOTINE
EPIDEMIOLOGIC STUDIES
AND SMOKELESS TOBACCO
data from Asia, 42-44
data from North America and
  Europe, 33-42
oral cancer, 33-44
other cancers, 47-55
EROSION (DENTAL)
defined, 128
ERYTHROPLAKIA
defined, 113
ESOPHAGEAL NEOPLASMS
case-control study, 39, 48-50
cohort study, 49-50
ESTMTED E2XkX?RE OF US
RESIDm To NITROSmES
  64
ESTLlzATED RELATWE RISKS
ASSOCL4TED WITH SNUFF USE
FOR ClANCERS OF TljlE ORAL
CAV7TI: PHARYNX, AND
LARYNX, CASECONTROL
DATA FROM VOGLER ETAL.,
Fm ONLY 38
EST~TEDRELAT~RLSKFOR
CMCER OF THEHEADAND
NECK FROM SMOKELESS
TOBACCO USE BY ANATOMIC
SITE, Tm NATIONAL CAN-
CER SUR VEX MALES ONLY 39
EST~TEDRELAT~RLSK OF
OROPHARYNGEU CANCER
ACCORDING To DURATION OF
SNUFF USEANDANAToM7C
SITE, Wm ET AL, 41
ESTWTES OF RELATNE RISKS
OF BLADDER CANC' LN
PERSONS WHO HA VE EVER
USED C%!EW~G TOBACCO
AND SNUFF 53
ETHNIC USE OF SMOKELESS
TOBACCO
of youth, 21-22
Experimental Studies Exposing
Laboratory Animals,
See ANIMAL MODELS

FORMATION OF TOBACCO
SPECUIC NITROSmES 60
FREQUENCY OF SMOKELESS
TOBACCO USE LN PAST YEARi
14

Gastric Neoplasms,
See STOMACH NEOPLASMS
GENERAL PRINCTPLESLN
EVALUATmTG CARCXNOGENIC
RISK OF CHEMC~S OR COM-
PLEX MLX-TURES (INTERNA-
TIONAL AGENCY FOR
RESEARCH ON CANCER, xxi
GINGIVAL AND PERIODONTAL
HEALTH
bone loss, 125
effects of smokeless tobacco, 101,
  103-104, 123
inflammation, 126
studies in Sweden, 126
studies in the United States, 125
GINGIVAL CARCINOMA
case studies, 34, 36, 44, 120
GINGIVAL RECESSION
Advisory Committee report, viii
defined, 123
related to oral leukoplakiai
mucosal pathology, 112
studies in the United States, 125
GINGIVITIS
defined, 123
relation to smokeless tobacco,
  125, 129
studies in the United States, 125
GLYCYRRHIZIC ACID
metabolic consequences, 179

HEAD AND NECK NEOPLASMS
case-control study, 38-39.38-39
HEROIN ADDICTION
THERAPY
model used, 156
HERPES SIMPLEX VIRUS
relation to oral cancer, 86-87, 93
HISTORICAL PERSPECTIVE
chewing tobacco, xvii
consequences of use, xviii-xix
decline of use, 5
early uses, xviii-xix, 5
snuff, xvii-xix
HYPERKERATOSIS
ccrhort study, 117-l 18
defined, 113
relation to snuff use, 125

189


HYPERORTHOKERATOSIS
cohort study, 118
defined, 113
HYPERPARAKERATOSIS
cohort study, 118-l 19
defined, 113
HYPOKALEMIA
nonnicotine metabolic
consequences, 179

INHALED SNUFF
relation to nasal carcinoma, 93

Kidney Neoplasms, See URINARY
TRACT NEOPLASMS

LARYNGEAL NEOPLASMS
/See also THIRD NATIONAL
CANCER STUDY)
case-control study, 37,38, 50-51
Leukoplakia, Oral, See ORAL
LEUKOPLAKIA
LIP NEOPLASMS (See also
ORAL CANCER)
animal models, 84-85
case-control study, 36
labial mucosa, 116-117
Looseleaf, See CHEWING
TOBACCO

MANLT?ACTURLNG TRENDS
QUANTLTLES OF SMORELESS
TOBACCO MANUFACTURED LN
THE UiWTED STATES FROM
1961 To 1985 EXPRESSED LN
JDLLION POUNDS. 8
MEAN FREQUENCY OF SMOKE
LESS TOBACCO USE DURING
LAST 7 DAYS BY ETHNLCITY
BY MALE RESPONDENTS, 23
METABOLIC PATHWAYS OF

NMOR, 74
ME;X&Xl$IC PATHWAYS OF
,A .

METkOLIC PATmA YS OF
Nvy 73
METABOLISM OF
CONSTITUENTS OF
SMOKELESS TOBACCO
conversion of products, xx-xxi
of NMOR, 74-75
of NNK, 71-73
of NNN, 73-74
MOUTH NEOPLASMS
(See also ORAL CANCER)
case-control study, 36-37.36, 37,
  39,120

MUCOSAL PATHOLOGY
snuff-induced lesions, 114-l 16
studies in Scandanavia, 11 l-l 12
studies in the United States, 107,
  108-109110-112
MUTAGENICITY ASSAYS AND
OTHER SHORT-TERM TESTS
(See also ANIMAL MODELS)
chewing tobacco, 88
snuff, 88
tobacco-specific N-nitrosamines,
  88-89

NASAL NEOPLASMS
posterior nasal space tumors, 48
relation to snuff use, 48
Nass, See ASIAN DATA
NATIONAL BLADDER
CANCER STUDY
relation to smokeless tobacco
  use, 52-53
NATIONAL BLOOD CANCER
STUDY
survey data, 16
NATIONAL HEALTH INTER-
VIEW SURVEY (NHIS)
survey data, 10, 14-15
NATIONAL INSTITUTE ON
DRUG ABUSE (NIDA)
survey data, 13-15
NATIONAL PREVALENCE OF
CURRENT USE OF SNUFF BY
GENDER AGE, AND RACE FOR
1980 THROUGH 1985,ll
NATION& PREVALENCE OF
SMOEELESS TOBACCO USE BY
ADCZT STATUS AND SEX,
INIDA SAMPLE, 1935, 13
NATIONAL PREVXLENCE OF
SMOKES TOBACCO USE:
DATA SOURCES, 9
NATIONAL SURVEY DATA
conclusions, 24-25
Current Population Survey, 12,14
discussion of data, 14-15
National Health Interview
  survey, 10, 14-15
National Institute on Drug
Abuse Household Survey, 13-15
Office on Smoking and Health
Surveys, 7,10,12,14
Simmons Market Research
  Bureau, 10, 12, 14-15

190


NEUROADAPTATION (See also
PHYSICAL DEPENDENCE
POTENTIAL OF NICOTINE,
PHYSIOLOGIC EFFECTS OF
NICOTINE)
defined, 145.
demonstrated, 153
nicotine, 162
NICOTINE (See also PHARMA.

COKINETICS OF NICOTINE,
NICOTINE ADDICTION,
NICOTINE EXPOSURE,
ABUSE LIABILITY, PHAR-
MACODYNAMICS OF NICO-
TINE, PATHOLOGIC
EFFECTS OF NICOTINE, AND
SMOKELESS TOBACCO)
absorption, 141-142, 185
cotinine levels, 143
dependence, 154
distribution, 142
elimination, 142-143
habituating agent, 58
levels, 143
physical dependence, 162-166
self-administration, 159-161
therapeutic effects, 154-155
turnover, 143
NICOTINE ADDICTION /See also

NICOTINE EXPOSURE,
PHYSICAL DEPENDENCE
POTENTIAL OF NICOTINE)
commonalities with other
  addictive substances, 146-147,
  152-157, 184
dose manipulations, 153
encourages other drug use, 184
pattern of use, 152
relation to smokeless tobacco, 58,
  144-147, 152, 185
self-administration, 152-153
social tolerance, 156
therapeutic effects, 154-155
tolerance of use developed, 153
treatment for, 155-156
NICOTINE ADDICTION
TREATMENT
blockade therapy, 156
nicotine gum, 156
pretreatment, 156
substitution, 156
supportive therapy, 156
NICOTINE CHEWING GUM
as substitution, 156
reinforcing properties, 166-167
research needs, 184
self-administration, 167

NICOTINE EXPOSURE
/See also NICOTINE,
NICOTINE ADDICTION)
delivery to the central nervous
system, 147
other physiological effects,
    .
  vm, xxii, xxvi
pharmacokinetics, xxiv, 141-144
peer pressure, 147, 152
reinforcer for animals, 147
relation to addiction, xxiv-xxv,

   144-157
XICOT~E SELF-ADMINISTRATION
PATTERIS. 161
NMOR /See also
ABBREVIATIONS)
metabolism in rats, 74-75
N-NITROSAMINES
(See also CARCINOGENS)
exposure in nontobacco
  products, 64, 64
in snuff, 60
in tobacco leaves, 59
metabolized by tissue, 70-75
nonvolatile, 60, 62
tobacco-specific, 60, 63
volatile, 60. 61
N-NflROSAMINES lN SMOKELESS
TOBACCO, 59
NNK (See also
ABBREVIATIONS)
metabolism in rats, 71-73
NNN (See also
ABBREVIATIONS)
metabolism in rats, 73-74
relation to buccal mucosa, 73
relation to lingual mucosa, 73
NONCANCEROUS CONDITIONS
(See also PRECANCEROUS
CONDITIONS)
relation to smokeless tobacco,
  100105
NONVOLATILE NITROSAWES
IN SMOIfELESS TOBACCO
(PPB), 62

OFFICE ON SMOKING AND
HEALTH (OSH)
survey data, 7, 10, 12, 14

ORAL CANCER (See also ORAL
LEUKOPLAKIA, ORAL SOFT
TISSUES, LIP NEOPLASMS,
MOUTH NEOPLASMS,
CHEEK NEOPLASMS, AND
TONGUE NEOPLASMS)

case studies, 34-41

191


ORAL CANCER-Cont.
epidemiologic studies, 33-55
in rats, 72, 79, 84-86, 88-89
ORAL LEUKOPLAKIA
causation, vii
defined, 113
prospective study, 118
relation to smokeless tobacco, viii,
  xxiii-xxiv, 107, 110-112, 121
studies in Scandanavia, 11 l-l 12
studies in the United States, 107,
  lot?-10!9, 110-112
ORAL SOFT TISSUES
clinical reports of lesions, 114-117
cohort studies, 117-119
definitions, 113-l 14
oral lesions, 119-120
transformation, 113-123

PANCREATIC NEOPLASMS
chewing tobacco use, 54-55
PARANASAL SINUS
NEOPLASMS
relation to snuff use, 48
PATHOLOGIC EFFECTS OF
NICOTINE AND SMOKELESS
TOBACCO
coronary and peripheral vascular
  disease, 177-178
hypertension, 178
nonnicotine metabolic
  consequences, 179
peptic ulcer disease, 178
pregnancy risks, 178-179
PERIODONTAL TISSUE
DEGENERATION (See also
MUCOSAL PATHOLOGY,
GINGIVAL AND
PERIODONTAL HEALTH)
and teenagers, 110
PERMIsslLE LlMIll!3 FOR
INDIVWUAL N-NITROSAMINES
AV CONSlIlX!TR PRODUCTS, 65
PHARMACODYNAMICS OF
NICOTINE
Liking Scale, 158
Morphine Benzadrine Group
  Scale, 158
research needs, 184
self-administration
implications, 162
PHARMACOKINETICS OF
NICOTINE
absorption, 141-142
cotinine blood levels, 143

PHARMACOKINETICS OF
NICOTINE-Cant .
distribution, 142
elimination, 142-143
levels in smokeless tobacco, 141
nicotine blood levels, 143
time course of turnover, 143
PHARYNGEAL NEOPLASMS
case-control study, 37,38, 39-40
cohort study, 41-42
PHYSICAL DEPENDENCE
POTENTIAL OF NICOTINE
(See also NEUROADAPTATION)
defined, 145,162
determination, 153-154
evidence for physical dependence,
  157-166
evidence of withdrawal
  symptoms, 164-166
implications of physical
  dependence, 166
reinforcement with nicotine
  gum, 167
studies conducted, 157, 162-163
tobacco withdrawal, 163-164
PHYSIOLOGIC EFFECTS OF
NICOTINE /See also NEURO-
ADAPTATION, PHYSICAL
DEPENDENCE POTENTIAL
OF NICOTINE)
cardiovascular system, 175-l 76
central nervous system, 147,176,
  183
differentiation possible, 162
endocrine system, 176
pleasant effects produced, 162,
  176
PLAQUE
defined, 128
use of smokeless tobacco, 130
Plug, See CHEWING TOBACCO
Polonium2Ia (21OPo),
See CARCINOGENS
Polynuclear Aromatic
Hydrocarbons (PAHI,
See CARCINOGENS
POSTERIOR NASAL SPACE
TUMORS
relation to liquid snuff, 48
PRECANCEROUS CONDITIONS
(See also NONCANCEROUS
CONDITIONS)
Advisory Committee Report, xxi
defined, 113
relation to leukoplakia, 119
relation to smokeless tobacco, xxi

192


PRECANCEROUS LESION
defined, 113
oral lesions, 119
PREVXLENCE OFSMOKELESS
TOBACCO USE BY CENSUS
REGION, 1985,16
PREVALENCE OF USE OF SMOKE
LESS TylBACCO AMONG YOUTH
BYGENDERANDGRADE
LOCAL SUR KEYS USING STAN-
DARDIZED QUESTIONS, 21-22
PREVALENCE OF USE OF SMOKE
LESS TOBACCO AMONG YOUTH
BY GENDER AND GRADE..
REGIONAL AND STATE LEVEL
SURVEYS REPORTED SINCE
1980,1&19
PREVALENCE OFSNUFFAND
CHEWING TOBACCO USE BY
ADULTM4LESlN10
GEOGRAPHIC AREAS 17
PREVALENCE OF SNUFF USE
AMONG COLLEGE STUDENTS
18 YEARS OF AGE OR OLDER
BY GENDER AND YEAR, 12
PREVALENCE OF THE USE OF
SNUFFAND CHEWmG TOBACCO
AMONG MALES BY AGE, 1970
NHLsAND1985cpssURVEY$ll

Quids, See ASIAN DATA

RECENCY OF SMOKELESS
TOBACCO USE BY SEXAND
AGE GROUP, 13
RELATmRfSK OFORAL CANCER
FROMBETEL QUID W7TLjlAND
W!IT.HOUT To&1CCO (WITH95
PERCENT CONFIDENCE
-), 43
RELATNERLSKS OF
ESOPHAGEAL CANCER lN
PERSONS ExposED To CHEW-
&VG TOBACCO AND SXX'i'?~
.!XlWXR Y OF M)UR CASE
CONTROL STUDHi! 49
Renal Neoplasms, See URINARY
TRACT NEOPLASMS
RESEARCH NEEDS
carcinogenesis, 93-94
nicotine exposure, 184-185
oral health effects 131-132
prevalence/trends of use, 25
standardizing methods, 25

SALIVA ANALYSIS
of snuff dippers, 64
SALIVARY GLANDS
effects of smokeless tobacco,
  lOl-l&3, 126-128
SCHEME LLNKLNG NICOTLNE TO
FORMATION OF THE
PROMUTAGENIC DNA ADDUCT
O%METHYLGUANINE, 72
SELECTED STUDY Sm
FOR THE NONC'CEROUS
ORAL HEALTH EFFECTS FROM
THE USE OF SMOKELESS
TOBACCO, lm105
SIALADENITIS
defined, 123
relation to smokeless tobacco, 127
relation to snuff dippers, 127
SIMMONS MARKET
RESEARCH BUREAU
survey data, 10, 12, 14-15
SMOKELESS TOBACCO (See also
CHEWING TOBACCO, SNUFF)
carcinogenesis associated with,
  33-93
chemical constituents, 58-69
cohort studies, 41-42
commonalities with other
  addictive substances, 146-147,
  152-157
conclusions, 24-25, 92-93,
  130-131, 182-183
effect on oral leukoplakia/
mucosal pathology, 107-l 12
epidemiologic studies and case
reports of oral cancer, 33-44
epidemiologic studies of other
  cancers, 47-55
evidence for abuse and
dependence, 166-167
experimental studies exposing
laboratory animals, 78-79
experimental studies of abuse
and dependence, 157-166
metabolism of constituents, 70-75
nicotine addiction, 144-146
nicotine exposure, xxiv, 141-185
noncancerous and precancerous
oral health effects, xxiii-xxiv,
  99-130
pharmacokinetics of nicotine,
  141-144
physiologic and pathologic
effects, 175-l 79
prevalence and trends of use.
xxii, 4-24

193


SMOKELESS TOBACCO-Cant .
product characteristics, 5
research needs, 25, 93-94,
  131-132, 184-185
transformation of oral soft
  tissue, 113-120
trends in production and sales,
  5, 7

trends in self-reported use, 7, 10,

12-17, 20, 24
SMOKELESS mBACC0 AND h!EAD
AND NECK CANCER BY ANA-
RMfICSITE, CASECONTROL
DATA FROM VtNCX!h'TAh?D
MARCtlETZA, - ONLU, 38
SMO- lloBACC0 AND
MOUTH CANCER CASE
CONTROL DATA FROM
MOOREETAL+ 36
SMO- TylBACCO AND
MOUTH CANCER, CASE
CONTROL DATA FROM
PEACOCKETAL, 37
SNUFF (See also SMOKELESS
TOBACCO, BIOASSAY8
ANIMAL MODELS)
case-control studies, 37, 40
characteristics. 5
dry,7
historical uses, xviii-xix
levels of carcinogens, 60, 64-66
moist, 7
relation to cancer, 41, 53-55
saliva analysis, 64
SNUFF-DIPPERS CARCINOMA
defined, 113
exposure to nitrosamines, 64
oral lesions, 120
reports, 35
Scandinavian study, 111
SQUAMOUS CELL CARCINOMA
case studies, 34-36
clinical study, 117
defined, 114
oral lesions, 119-120
snuff and ear neoplasms, 47
STAINING (DENTAL)
defined, 129
STATE AND LOCAL SURVEY
DATA
adolescent use, 17, 20, 24-25
adult use, 16-17
STOMACH NEOPLASMS
relation to smokeless tobacco,
  51-52

Substitution Therapy, See
NICOTINE ADDICTION
TREATMENT
SUMMRY OF DATA: LIABILJTY
OF NICOTmTE AS mBACC0
SMOKE OR lNTRAVENOUS
lh?JECTION$159
StJUX4RYOFREFOR~IN
WZICHNICOT~ WAS AVAII
ABLE uNoERINTR.AvENom
DRUG SELF+tDMIhZXUATION
PROC%!DiXE!$14&151
S-Y OFSELJXTZD CASE
REpoRT$106
Supportive Therapy, See
NICOTINE ADDICTION
TREATMENT
Surgeon General's Advisory
Committee on the Health
Consequences of Using Smokeless
`Ibbacco, See ADVISORY
COMMITTEE TO THE SUR-
GEON GENERAL, REPORT

TEETH
dental caries, 129-130
effect of smokeless tobacco,

128-130

other hard tissue effects, 130
THERAPEUTIC EFFECTS OF
NICOTINE
as an anoretic, 154
mood regulator, 154
performance of cognitive tasks,
  154
self-medication, 155
work enhancement, 154
THIRD NATIONAL CANCER
STUDY (TNCS)
bladder cancer, 54
laryngeal neoplasms, 50-51
other cancer sites, 55
stomach neoplasms, 52
TOBACCO SNIFFING
rare practice, xvii
TOBACCMPEC~IC
N-NITR-B liV SMOKE
LhXJ TOBACCO fPPB), 63
mBA CCO-SPECXFIC
N-NITRO-Bmm'
US. BRANI& 1985,66
TOBACCO WITHDRAWAL
(See also PHYSICAL DEPEN-
DENCE OF NICOTINE)
evidence of symptoms, 164-166

194


TOBACCO WITHDRAWAL-
Cont.
study findings, 165
symptoms, 163-164
University of Minnesota
  studies, 164-166
`TONGUE NEOPLASMS (See also
ORAL CANCER, MOUTH
N-EOPLASMS)
case-control study, 36,120
TRENDS IN PRODUCTION
ANDSALES
categories of products, 7
temporal trends, 7
United States Department of
Agriculture (USDA) reports, 5
TRENDS IN SELF-REPORTED
USE: SURVEY DATA
national survey data, 7, 10, 12-15
state and local survey data,
  15-1'7, 20, 24
Twist, See CHEWING TOBACCO

URINARY TRACTNEOPLASMS
castxontrol studies, 52-54
relationship to smokeless
tobacco, 52-54

USEOFSMO-llylBAccOm
THE UNITEB SZ4TEs BY

VAlpIATIONs~ T- USEDm
DEI?!ONS PROKiDED EylR
GINGMTISAND GINGWXL RE
C%ssIONBYS~~ CITED, 124
VMU4TIONS~ TERbis USEDAND
D,W!MIONS PROKWED EylR

USED BY STuDrn CITED,
108109
VERRUCOUS CARCINOMA
defined, 114
dysplastic lesions, 13 1
voLAlzLEm-m
MfOKI.hZSS mBACc0 IPPBJ,
61

WORLD HEALTH
ORGANIZATION (WHO)
Chnmittee on Drug Dependence,
  145
defines oral leukoplakia, 107
differing diagnoses, 123

195