Report
of the
Secretary's (Commission
on
Pesticides
and
Their Relationshij
Environmental Health
Parts I and II
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
December 1969
-------
of the
Secretary's Commission
on
Pesticides
and
Their Relationship
to
Environmental Health
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
For sale by the Superintendent of Documents, U.S. Government Printing Ofllcc
Washington, D.C. 20402 - Price $3.00
December 1969
-------
TABLE OF CONTENTS
Page
Letter of Transmittal v
Acknowledgments
Membership of the Commission vi
Membership of the Commission Subcommittees viii
Membership of the Advisory Panels ix
Acknowledgements to Other Contributors xiii
Part I. Commission Recommendations on Pesticides 1
Letter of Transmittal 3
Introduction 5
Commission Recommendations 7
Summaries of Subcommittee Reports 21
Part II. Subcommittee and Panel Reports 39
Chapter 1. Uses and Benefits 41
Chapter 2. Contamination 99
Chapter 3. Effects of Pesticides on Nontarget Organisms
Other Than Man 177
Chapter 4. Effects of Pesticides on Man 229
Chapter 5. Carcinogenicity of Pesticides 459
Chapter 6. Interactions 507
Chapter 7. Mutagenicity of Pesticides 565
Chapter 8. Teratogenicity of Pesticides 655
Hi
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DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
December 5, 1969
Dear Mr. Secretary:
The complete report of your Commission on Pesticides and Their
Relationship to Environmental Health (Part I & Part II) is
included herein<.
Part I, which I submitted to you on November 11, 1969, contains
the Commission's unanimous recommendations along with summaries
of the reports of four Subcommittees to the Commission.
Part II contains the complete reports and conclusions of four
Subcommittees and the four Advisory Panels to the Commission,
upon which findings the Commission based its recommendations.
Over 5000 references to published or ongoing scientific research
were reviewed and evaluated. Since each report was prepared by
the membership of the Subcommittee or Advisory Panel involved
with the particular subject under review, these reports by
themselves do not necessarily reflect the unanimous opinion
of the Commission1s entire membership, although each Commission
member has reviewed all drafts of all reports. However, the
recommendations of the Commission were adopted unanimously.
On behalf of the Commission, its entire staff, and speaking for
myself, I would like to thank you for the superb support you and
your Department have given to the Commission. We hope that our
recommendations will be considered for early implementation by
all Departments concerned with the use of pesticides.
Honorable Robert H. Finch
Secretary
Department of Health, Education,
and Welfare
Washington, D. C.
Enclosures
Sincerely yours
Emil M, Mrak
Chairman
Secretary's Commission on Pesticides
and Their Relationship to Environmental
Health
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MEMBERSHIP OF THE
COMMISSION
Db. Emil M. Mkak—Chairman
Chancellor Emeritus, University of California at Davis
Db. William J. Darby—Vice Chairman
Chairman, Department of Biochemistry, Vanderbilt University
Dr. Edwin F. Alder
Vice President, Agricultural Research
and Development
Eli Lilly and Company
Dr. Lamont C. Cole
Professor and Chairman, Department
of Zoology
Division of Biological Sciences,
Cornell University
Dr. Julius E. Johnson
Director of Research
Dow Chemical Company
Mr*. Virginia Knaucr
Special Assistant to the President for
Consumer Affairs, The White House
alternate; Francis McLaughlin,
Director, Producer Marketing
Relationships, President's Com-
mittee on Consumer Interests
Dr. Eugene Cronin
Director and Research Professor,
Natural Resources Institute and
Chesapeake Biological Laboratory
University of Maryland
Dr. Leon Qolberg
Scientific Director, Research Profes-
sor of Pathology Institute of Experi-
mental Pathology and Toxicology
Albany Medical College
Dr. Gordon Guyer
Chairman, Department of Entomology
Michigan State University
Prof, Morton S. Hilbert
Department of Environmental Health,
University of Michigan
1 Resigned—insufficient time available.
Dr. Thomas H. Milby
Chief, Bureau of Occupational Health
and Environmental Epidemiology
California Department of Public
Health
Dr. Daniel A. Okun
Head, Department of Environmental
Sciences and Engineering
University of North Carolina
Dr. David Pimentel
Head, Department of Entomology and
Limnology
State University of New York College
of Agriculture, Cornell
Dr. Leonell C. Strong1
Director, Leonell C. Strong Research
Foundation
W
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Commission Staff Members
Dr. Ai-heht (.5. Kolbyk, Jr., Executive (Secretary and Staff Director
Special Assistant (for Standards and Compliance) to the Deputy Administrator,
Consumer Protection and Environmental Health Service
Dr. Dale R. Linosay, Special Assistant to the Commission
Associate Commissioner for Science, Food and Drug Administration
Dr. John R. J>avies, Special Assistant to the Commission
Community Studies on Pesticides, Dade County Department of I'uWic Health, Flu.
» • •
Mr. W. WaijeTalbot, Executive Officer
Chief, I,al>orator,v Services Brunch, Bureau of Science
Fowl and Drug Administration
Mr. IlKitscmu, F. Ci-khnbli
Inventions Adviser, Health Services and Mental Health Administration
Mr. Ikving Gerkixu
Executive Secretary, Special Study Sections
Division of Research Grants, National Institutes of Health
Dr. Ti IOMAS W. IIaiNKS
Office of Grants Management, l'ultlic Health Service
U.S. Department, of Health, Education, and Welfare, Region IV
Mr. Robert li. Hahwick, Previous Executive Officer,
Secretary's Commission on Pesticides
Executive Otficer, Environmental Control Administration
Dr. Rob S. McCutcheon
Executive Secretary, Toxicology Study Section
Division of Research Grants, National Institutes of Health
Dr. G. BUKROUGHs Mideu
Acting Deputy Director, National Library of Medicine
Mr, LesselL. Ramsey
Assistant Director for Regulatory Programs
Bureau of Science, Food and Drug Administration
Mr, ,T. Stijakt Rich
Printing Officer, Social Security Administration
Mr. Jamks G. Tkuiiill, Jr.
SfH-'ciul Assistant to the Administrator
Consumer Protection and Environmental Health Service
Dr. William M. Upholt
Executive Secretary, Federal Committee 011 Pest Control
Food and Drug Administration
Dr. Harold W. Wolf
Director, Division of Criteria and Standards, Bureau of Water Hygiene
Environmental Control Administration
vii
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MEMBERSHIP
OF THE COMMISSION
SUBCOMMITTEES
Subcommittee on Uses and Benefits of Pesticides
Dr. Gordon E. Guyer, Chairman Dr. Lamont C. Cole
Dr. Edwin F. Alder Dr. Thomas W. Haines, Staff
Subcommittee on Contamination
Dr. Daniel A. Okiin, Chairman Dr. Harold W. Wolf, Staff
Professor Morton S. Hilbert
Subcommittee on the Effects of Pesticides on
Nontarget Organisms Other Than Man
Dr. L. Eugene Cronin, Chairman Dr. David Pimentel
Dr. Julius E. Johnson Dr. William M. llpholt, Staff
Subcommittee on Effects of Pesticides on Man
Dr. Leon Golberg, Chairman Dr. John E. Davies
Dr. Thomas H. Milby Mr. James G. Terrill, Jr., Staff
Subcommittee on Criteria and Recommendations
Dr. William J. Darby, Chairman Dr. Leoaell C. Strong
MrB. Virginia Knauer Mr. Lessel L. Ramsey, Staff
Mr. Francis McLaughlin—Alternate
viii
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MEMBERSHIP OF THE
ADVISORY PANELS
Advisory Panel on Carcinogenicity of Pesticides
Dr. William J. Darby, Chairman
Chairman, Department of
Biochemistry
Vanderbilt University School of
Medicine
Dr. Ian A. Mitchell, Panel Executive
Secretary
Assistant Director, National Cancer
Institute
Dr. Harry P. Burehfleld
Director, Division of Biological
Sciences
Gulf South Research Institute
Dr. David Gaylor
Mathematical Statistician, Biometry
Branch
National Institute of Environmental
Health Sciences
Dr. Paul Kotin
Director, National Institute of
Environmental Health Sciences
Dr. James A. Miller
Professor, Department of Oncology,
University of Wisconsin
Dr. Norton Nelson
Director, Institute of Environmental
Medicine
New York University Medical
Center
Dr. Marvin A. Schneiderman
Associate Chief, Biometry Branch,
National Cancer Institute
Mr. Carroll Weil
Senior Fellow, Carnegie-Mellon Uni-
versity
List of Nonmember Participants in the
Meetings of the Advisory
Panel on Carcinogenesis1
Richard R. Bates, M.D.
National Cancer Institute
Mr. Joseph Cummings
Food and Drug Administration
Kent J. Davis, D. V. M.
Food and Drug Administration
Samuel S. Epstein, M.D.
Children's Cancer Research
Foundation
Hans Ij. Falk, Ph. D.
National Institute of Environmental
Health Sciences
1 The panel is grateful to the above-named participants for their suggestions and valuable
contributions to this document. However, It should be noted that the judgments recorded
In the panel report are those of the panel members.
ix
-------
O. Garth Fitzhugh, Ph. D.
Food and Drug Administration
John Gart, Ph. D.
National Cancer Institute
Mv. Irving Gerring
National Institutes of Health
Leon Golberg, M. B.
Albany Medical College
Mr. Stuart L. Graham
Food and Drug Administration
Adrian Gross, Ph. D.
Food and Drug Administration
Mary Ellen Kitler, Ph. D.
Johns Hopkins University
Albert C. Kolbye, Jr., M. D.
Consumer Protection and
Environmental Health Service
Douglas Lee, M. D.
National Institute of Environmental
Health Sciences
Marvin S. Legator, Ph. D.
Food and Drug Administration
Dale R. Lindsay, Ph. D.
Food and Drug Administration
Rob S. McCutcheon, Ph. D.
National Institutes of Health
Joseph McLaughlin, Ph. D.
Food and Drug Administration
G. Burroughs Mider, M. D.
National Library of Medicine
Emil Mrak, Ph. D.
University of California at Davis
James Peters, D. V. M.
National Cancer Institute
Mr. L. L. Ramsey
Food and Drug Administration
Umberto Safflotti, M. D.
National Cancer Institute
Mr. James G. Terrlli, Jr.
Consumer Protection and Environ-
mental Health Service
Advisory Panel on Interactions
Dr. Kenneth DuBois, Chairman
Professor, Department of Pharmacol-
ogy, University of Chicago
Dr. Rob S. McCutcheon, Panel Execu-
tive Secretary
Executive Secretary, Toxicology Study
Section
Dr. John Casidu
Professor of Entomology, University
of California
Dr. Cipriano Cueto, Jr.
Chief, Pharmacology Section, Perrine
Primate Research Branch
Food and Drug Administration
Dr. John Doull
Professor of Pharmacology, University
of Kansas Medical Center
Dr, Richard D. O'Brien, Vice Chair-
man
Professor and Chairman, Section of
Neurobiology and Behavior
Cornell University
Dr. John P. Frawley
Chief Toxicologiat, Hercules Incor-
porated
Dr. Christopher Wilkinson
Assistant Professor, Department of
Entomology
Cornell University
Dr. Samuel E. Epstein, Liaison
Chief, Laboratories of Environmental
Toxicology and Carcinogenesis
Children's Cancer Research Founda-
tion, Inc.
X
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Advisory Panel on Mutagenicity of Pesticides
IJr. Samuel 8. Epstein, Chairman
Chief, Laboratories of Environmental
Toxicology and Carcinogenesis
Children's Cancer Research Founda-
tion, Inc.
Dr. Marvin Legator, Panel Executive
Secretary
Chief, Cell Biology Branch, Bureau of
Science
Food and Drug Administration
Dr. James Crow
Professor, Department of Genetics and
Medical Genetics
University of Wisconsin
Dr. Ernest Freese
Chief, Molecular Biology, Laboratory
of Molecular Biology
National Institute of Neurological Dis-
eases and Stroke
Dr. Albert C. Kolbye, Jr.
SiH'cial Assistant (for Standards and
Compliance) to the Deputy Admin-
istrator
Consumer Protection and Environ-
mental Health Service
I>r. Heinrich Mailing
Biology Division, Oak Ridge National
Laboratory
Dr. John Neumeyer
Professor, Medicinal Chemistry,
Northeastern University
Dr. Warren Nichols
Head, Department of Cytogenetics,
Institute of Medical Research
Mr. Irving Gerring, Staff
Executive Secretary, Special Study
Sections
Division of Research Grants, National
Institutes of Health
Dr. Rob S. McCutcheon, Staff
Executive Secretary, Toxicology
Study Section
Division of Research Grants, National
Institutes of Health
Dr. Christopher Wilkinson, Liaison
Assistant Professor, Department of
Entomology
Cornell University
Nonmember Contributors
Mr. Seymour Abrahamson
University of Wisconsin
Dr. P. J. Bottino
Brookhaven National Laboratory
Dr. L. A. Schairer
Brookhaven National Laboratory
Dr. A. H. Sparrow
Brookhaven National Laboratory
Dr. J. S. Wassom
Oak Ridge National Laboratory
Advisory Panel on Teratogenicity of Pesticides
Dr. Joseph McLaughlin, Jr., Cock air-
man
Food Toxicology Branch, Bureau of
Science
Food and Drug Administration
Dr. David Gaylor
Mathematical Statistician, Biometry
Branch
National Institute of Environmental
Health Sciences
Dr. Samuel S. Epstein, Cochairman
Chief, Laboratories of Environmental
Toxicology and Carcinogenesis
Children's Center Research Founda-
tion, Inc.
Mr. Irving Gerring, Staff
Executive Secretary, Special Study
Sections
Division of Research Grants, National
Institutes of Health
xi
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Dr. Michael D. Hogan, Statistician,
National Institute of Environmental
Health Sciences
Dr. Harold Kalter
Associate Professor of Research Pedi-
atrics, Department of Pediatrics
Children's Hospital, Cincinnati, Ohio
Dr. Cecil T. G. King
Chief, Pharmacology Section, Labora-
tory of Biochemistry
National Institute of Dental Research
I>r. Albert C. Kolbye, Jr.
Special Assistant (for Standards and
Compliance) to the Deputy Admin-
istrator, Consumer Protection and
Environmental Health Service
I)r. Rob S. McCutcheon, Staff
Executive Secretary, Toxicology Study
Section
Division of Research Grants, National
Institutes of Health
Dr. Robert W. Miller
Chief, Epidemiology Branch, National
Cancer Institute
Dr. James A. O'Leary
Director, Division of Experimental
Gynecologic Surgery
Department of Obstetrics and Gynecol-
ogy, University of Miami
Dr. Herbert J. Schumacher
Associate Professor, Environmental
Health
College of Medicine, University of Cin-
cinnati
Mr. James G. Terrill, Jr., Staff
Special Assistant to the Administrator
Consumer Protection and Environmen-
tal Health Service
xii
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ACKNOWLEDGEMENTS TO
OTHER CONTRIBUTORS
Gratitude is expressed by the Commission to the Consumer Pro-
tection and Environmental Health Service which provided continuing
administrative services and staffing support throughout the Com-
mission's deliberations and contributed substantially towards the fund-
ing of the Commission's objective. Appreciation also is extended to
the National Institutes of Health and the National Library of Medicine
for providing additional support and resources.
Special thanks go to members of the staff of the Office of the
Secretary of Health, Education, and Welfare: Mr. B. Michael Kahl,
Assistant to the Secretary for Public Affairs; Mr. W. Phillips Rocke-
feller; and Mr. Robert V. Pauley.
The Commission is indebted to the Public Printer and the staff of
the U.S. Government Printing Office for the superb and efficient man-
ner in which this report was produced.
The following is a partial list of persons who have contributed
valuable information or services to the Commission. The Commission
would like to express its deep appreciation to them and to the many
other individuals who inadvertently may not be listed herein.
Mr. Harold G. Alford
U.S. Department of Agriculture
Col. Robert M. Altaian
Walter Reed Army Medical Center
Dr. Robert Anderson
U.S. Department of Agriculture
Dr. Harold Baer
National Institutes of Health
Dr. John R Bagby
National Communicable Disease
Center
Mr. S. C. Billings
U.S. Department of Agriculture
Dr. Alexej Borkovec
U.S. Department of Agriculture
Dr. Blair Bower
Resources for the Future,
Washington, D.O.
Dr. A. M. Boyce
Consultant to Rockefeller Foundation
Dr. Parke C. Brinkley
National Agricultural Chemical
Association
Dr. A. W. A. Brown
World Health Organization,
Switzerland
xiii
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Dr. Philip A. Butler
U.S. Department of the Interior
Mr. E. Buyckx
Fowl & Agriculture Organization of
the United Nations
Mr. Thomas A. Calabresa
Wisconsin Department of Natural
Resources
Douglas D. Caton
Agency for International
Development
Department of State
Mr. G. V. Chambers
ES'SO Research and Engineering
Co.
Baytown, Tex.
Dr. John E. Christian
Purdue University
Mr. G. S. Christopher
Tennessee Valley Authority
Dr. Ronald A. Chung
Tuskegee Institute
Mr. Roland C. Clement
National Audubon Society
Dr. Patricia A. Condon
National Agricultural Library
Mr. J. William Cook
Food and Drug Administration
Dr. J. M. Coon
Jefferson Medical College
Dr. Oliver B. Cope
U.S. Department of the Interior
Dr. Lawrence R. Cory
St. Mary's College of California
Dr. Robert D. Courter
Food and Drug Administration
Dr. Reynold G. Dahms
U.S. Department of Agriculture
Mr. Velmar W. Davis
U.S. Department of Agriculture
Dr. William B. Deichmann
University of Miami
xiv
Mr. Elmer C. Denis
Doane Agricultural Services, Inc.
St. Louis, Mo.
Dr. Hugh Dierker
Executive Secretary and Director
of Health, State of Kansas
Dr. Alan W. Donaldson
Health Services and Mental
Health Administration
Dr. William F. Durham
Food and Drug Administration
Dr. Eugene Dustman
U.S. Department of the Interior
Mr. Walter W. Dykstra
U.S. Department of the Interior
Dr. Chris M. Elmore, Jr.
Gulf Coast Mosquito Control
Commission, Gulfport, Miss.
Mr. George H. Engle
Ohio Department of Health
Dr. William Ennis
United States Department of
Agriculture
Dr. Mostafa Fahim
University of Missouri School of
Medicine
Dr. Henry Fischbach
Food and Drug Administration
Mr. Charles Fisher
Coast Laboratories, Fresno, Calif.
Dr. Joe Fisher
Resources for Future
Washington, D.C.
Mr. Austin S. Fox
U.S. Department of Agriculture
Dr. John P. Frawley
Hercules, Inc.
Dr. Virgil H. Freed
Oregon State University
Dr. E. D. Goldberg
University of California
San Diego, La Jolla, Calif.
Dr. Vernon A. Green
The Children's Mercy Hospital
Kansas City, Missouri
-------
Dr. H. B. Gunner
University of Massachusetts
Dr. Wayland J. Hayes, Jr.
Vanderbilt University Medical School
Dr. Harry W. Hays
U.S. Department of Agriculture
Dr. Joseph C. Headley
University of Missouri
Dr. Ralph Heel
National Pest Control Association,
Elizabeth, N.J.
Dr. Don R. Heinicke
U.S. Department of Agriculture
Dr. Alexander Hollaender
Oak Ridge National Laboratories
Dr. C. G. Hoskin
Illinois Institute of Technology
Chicago, 111.
Dr. George B. Hutchison
Michael Reese Hospital, Chicago, 111.
Dr. George Irving
U. S. Department of Agriculture
Dr. Ray Johnson
U.S. Department of the Interior
Dr. Georg Jorgeson
Boyee-Thompson, Yonkers, N.Y.
Dr. Thomas H. Jukes
University of California,
Berkeley, Oalif.
Dr. Robert L. Kaiser
National Communicable Disease
Center
Dr. Donald Kaufman
U.S. Department of Agriculture
Dr. Philip Kearney
U.S. Department of Agriculture
Dr. Jubee Kim
California State College, Long Beach
Calif.
Mr. Ivan Kinney
Bitelle, Inc., Columbus, Ohio
Mr. C. W. Klaasen
Illinois Department of Public Health
Dr. E. F. Knipling
U.S. Department of Agriculture
Dr. Herbert C. Knutson
Kansas State University
Mr. Kenneth K. Krausche
National Agricultural Chemical
Association
Dr. Herman F. Kraybill
Food and Drug Administration
Dr. L. W. Larson
U.S. Department of Agriculture
Dr. Edwards R. Laws, Jr.
Johns Hopkins Hospital
Mr. Allen Lemon
California Department of Agriculture
Dr. E. P. Liechtenstein
University of Wisconsin
Mr. L. A. Liljedahl
U.S. Department of Agriculture
Dr. G Lofroth
University of Stockholm
Mr. Bernard Lorant
Velsicol Chemical Corp.
Dr. Kenneth J. Macek
U.S. Department of the Interior
Dr. Howard I. Maibach
University of California, San Fran-
cisco, Calif.
Mr. Marion C. Manderson
Arthur D. Little, Inc.
Mr. Vernon G. McKenzie (Retired)
Public Health Service
Dr. David R. Metcalf
University of Colorado Medical Center
Dr. Robert L. Metcalf
University of Illinois
Dr. Dudley P. Miller
Grafton, Vt.
Mr, Arthur D, Moore
Pacific Southwest Forest and Range
Experimental Station,
Berkeley, Calif.
XV
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Mr. Alfred A. Mullikesn
Chemical Specialty Manufacturers As-
sociation
New York, N.Y.
Mr. Kenneth B. Nash
U.S. Department of Agriculture
Dr. Ralph Nash
U.S. Department of Agriculture
Dr. Gordon R, Neilson
University of Vermont
Dr. William A. Niering
Connecticut College
Dr. Robert Olson
Stanford Research Institute
Mr. John Osguthorpe
U.S. Department of State
Dr. George W. Pearce
National Communicable Disease
Center
Dr. Tony J. Peterie
Ohio State University
Mr, George Peterson
Agency for International Development
Mr. B. A. Poole
Indiana State Board of Health
Dr. Hans Popper
Mount Sinai School of Medicine
Mr. Arthur Poulos
Chemical and Engineering News,
Washington, D.C.
Dr. Ken Quarterman
National Communicable Disease
Center
Dr. Griffith E. Quinby
Wenatchee, Wash.
Dr. William Reals
St. Joseph's Hospital and Rehabilita-
tion Center, Wichita, Kans.
Dr, L. B. Reed
U.S. Department of Agriculture
Dr. J. Robinson
Shell Research Limited,
London, England
Dr. Recce 1. Sailer
U.S. Department of Agriculture
Dr. Arthur J. Samuels
California Hematological Institute,
Los Angeles, Calif.
Dr. Herbert F, Schoof
National Communicable Disease
Center
Dr. David Sencer
National Communicable Disease
Center
Mr. W. B. Shafer
Stauffer Chemical Co.
Dr. Donald R. Shepherd
U.S. Department of Agriculture
Mr. M. J. Sloan
Shell Chemical Co.
Dr. Philip J. Spear
National Pest Control Association,
Inc., Elizabeth, N.J.
Dr. S. W. Simmons
Food and Drug Administration
Dr. James V. Smith
National Communicable Disease
Center
Dr. Ira I. Somers
National Qanners Associations,
Washington, D.C.
Donald A. Spencer
National Agricultural Chemical
Association
Dr. Lucille M. Stickel
U.S. Department of the Interior
Mr. William Stickel
U.S. Department of the Interior
Dr. J. O. Street
Utah State University
Dr. John E. Swift
University of California, Berkeley,
Calif.
Dr. Irene Till
Social Security Administration
xvi
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Dr. Fred Tschirley
U.S. Department of Agriculture
Dr. B. G. Tweedy
University of Missouri
Dr. B, Dwain Vance
North Texas State University
Dr. Charles H. Van Mlddelem
University of Florida
Mr, John E, Vogt
Michigan Department of Public
Health
Mr. Charles Walker
U.S. Department of the Interior.
Mr. Justus Ward
U.S. Department of State
Dr. George W. Ware
University of Arizona
Mr. Richard O. White
U.S. Department of Agriculture
Dr. James L. Whittenberger
Harvard University
Dr. Frank G. Wilkes
University of North Carolina
Dr. Christopher F. Wilkinson
Cornell University
Dr. J. Henry Wills
Albany Medical College
Dr. George Woodwell
Brookhaven National Laboratory
Mr. Ross Wurn
Ross Wurn and Associates, Modesto,
Calif.
Dr. Charles F. Wurster, Jr.
State University of New York
Dr. Anne R. Yobs
Food and Drug Administration
Dr. Gunter Zweig
Syracuse University
The following U.S. Department of Health, Education, and Welfare administra-
tive staff contributed to the preparation of this report Thanks is also extended to
Mr. Lacy L. Vaughn, Chief Reproduction Services and members of his Branch
for the expedient support given to the Commission. Special appreciation is ex-
tended to Mrs. Dorothy I. Richards and Mrs. Sara J. Timmons:
Mrs. Elizabeth R. Barber Miss Carolyn L. Osborne
Miss Marian DeCamp Miss Marjorie V. Stover
Miss Jeanette C. Harris Miss Rosemary Tobin
xvif
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Part I
Commission Recommendations
on Pesticides
-------
DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
November 11, 1969
Dear Mr, Secretary:
Attached are the unanimous recommendations of your Commission on
Pesticides and Their Relationship to Environmental Health. As
you know, the reports of the Commission, eight*in all, are in the
process of publication as you have directed.
These recommendations are arranged in an action priority order as
seen by the Commission; however, this order has no significance as
to their relative importance. In my own view the recommendations
support the following principles:
1. Chemicals, Including pesticides used to increase food
production, are of such importance in modern life that
we must learn to live with them;
2. In looking at their relative merits and hazards we must
make Individual judgments upon the value of each chemical,
including the alternatives presented by the non-use of
these chemicals. Ue must continue to accumulate scientific
data about the effects of these chemicals on the total
ecology; and
3. The final decision regarding the uBage of these chemicals
must be made by those governmental agencies with the
statutory responsibilities for the public health, and for
pesticide registration.
On behalf of the Commission and all of the staff assigned to help
the Commission, I want to express our thanks for the support you
have given us in carrying out this task. We hope that our efforts
will be helpful to you in carrying out your awesome responsiblliteB.
Honorable Robert H. Finch
Secretary
Department of Health, Education,
and Welfare
Washington, D.C.
Enclosures
Sincerely yours,
Chairman
Secretary's Commission on Pesticides and
Their Relationship to Environmental Health
3
-------
INTRODUCTION
Our society 'has gained, tremendous benefits from the usage of pesti-
cides to prevent disease and to increase the production of foods and
fibers. Our need to use pesticides and other pest control chemicals will
continue to increase for the foreseeable future. However, recent evi-
dense indicates our need to be concerned about the unintentional effects
of pesticides on various life forms within the environment and on hu-
man health. It is becoming increasingly apparent that the benefits of
using pesticides must be considered in the context of the present and
potential risks of pesticide usage. Sound judgments must be made.
The Secretary's Commission on Pesticides and Their Relationship
to Environmental Health was appointed in April 1969 and charged
with the responsibility of gathering all available evidence on both the
benefits nad risks of using pesticides, evaluating it thoroughly, and
reporting their findings and recommendations to Secretary Finch.
After carefully reviewing all available information, the Commission
has concluded that there is adequate evidence concerning potential
hazards to our environment and to man's health to require corrective
action. Our Nation cannot afford to wait until the last piece of evidence
has been submitted on the many issues related to pesticide usage. We
must consider our present course of action in terms of future genera-
tions of Americans and the environment that they will live in.
The Commission's unanimously approved recommendations, devel-
oped after careful evaluation of all available evidence, are presented
in this document. Part II of this report currently is in preparation for
printing and will be made available in the near future. This represents
the review of over 5,000 references to scientific research, and will con-
tain a full presentation of each Sub-Committee's Report to the Com-
mission, including special Advisory Panel Reports on carcinogenesis,
interaction, mutagenesis, and teratogenesis. We must consider the total
problem of pesticide usage not only in the context of what is presently
known but also in the context of the many unknowns still to be deter-
mined, Some of these unknowns may never be precisely determined.
Corrective action is recommended now to prevent further environ-
mental contamination from pesticide residues and to protect the health
of man.
5
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COMMISSION
RECOMMENDATIONS
Recommendation 1:
Initiate closer cooperation among the Departments of Health, Edu-
cation, and Welfare, Agriculture, and Interior on pesticide problems
through establishment of a new interagency agreement.
The registration of pesticides is now vested only in the Secretary
of Agriculture under the Federal Insecticide, Fungieide, and Rodenti-
cide Act (FIFRA). The regulations implementing FIFRA state that
the purpose of the act is "to protect the public health before injury
occurs rather than to subject the public to dangers of experimentation
and take action after injury." 1 However, the present interagency
agreement requires the Secretaries of DHEW and USDI to produce
scientific evidence clearly demonstrating a present hazard to health
or to the environment in order to remove from registered use or pre-
vent the registration of any specific pesticide. In regard to health pro-
tection, the burden of proof should rest upon the manufacturer to
demonstrate to the Secretary of HEW that appropriate tests do not
produce untoward effects upon two or more species of mammals which
might indicate a hazard to health. Such a procedure is entirely in
keeping with the purpose of the act as stated above.
A new interagency agreement is needed to strengthen cooperative
action among the Departments of HEW, USDA, and USDI to protect
public health and the quality of the environment from pesticide haz-
ards. Approval by the Secretaries of DHEW and Interior as well as
Agriculture should be required for all pesticide registrations. Pesti-
cide uses deemed by any of the three Secretaries to be hazardous should
be restricted or eliminated.
The agreement should further require a continuous review of new
scientific information on pesticides now in use, with a formal review
made 2 years after initial registration and subsequent formal reviews
by the three agencies at 5-year intervals.
1CJ.H., Title 7, Cr. 11, Sec. 302.106(d) (1).
7
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Such an agreement and the closer interagency cooperation it would
produce would have other distinct advantages:
• It would call attention to evidence suggesting concern and expe-
dite appropriate action;
• It would encourage cooperative approaches to public education,
applicator training, research 011 the biological effects of a pesti-
cide, and promote the development and use of improved methods
of pest control; and
• It would provide a mechanism for focusing the concerns and
skills of each agency and to coordinate action on pesticide
problems.
If the objective of providing to the Secretary of DHEW the au-
thority to meet his responsibility for control of health hazards of pesti-
cides cannot be attained by a new interagency agreement, it will be
necessary to amend the Federal Insecticide, Fungicide, and Rodenti-
cide Act (FIFRA).
Recommendation 2:
Improve cooperation among the tuition* elements of the Department
of Health, Education, and W elf are which are concerned with the effects
of pest control and pesticides.
The diversified and significant responsibilities associated with the
Department of Health, Education, and Welfare pesticide and pest-
control activities lack sufficient coordination and direction. Several
segments of DHEW have direct and implied responsibilities for pro-
teciton of public health in relation to the use of pesticides. The prob-
lem of achieving cooperation appears to be intensified by recent reor-
ganizations. Mechanisms should be developed to assure exchange of
information between all pertinent segments of DHEW. There is a
need for reappraisal of the vector control activities, educational pro-
grams, research responsibilities, monitoring, State aid programs, and
other activities involving pesticides.
Recommendation 3:
Eliminate within two yearn all men of DDT and DDD in the, United
States excepting those uses essential to the preservation of human
health, or welfare and approved unanimously by the Secretaries of the
Departments of Health, Education, and Welfare, Agriculture, and
Interior.
The uses of DDT and DDD as pesticides should be limited to the
prevention or control of human disease and other essential uses for
which no alternative is available. Such uses should be clearly identi-
fied and individually evaluated in relation to human hazard from ex-
posure, movement in the natural environment concentration in the food
8
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chains of the world, and other environmental considerations. Unani-
mous approval by the Secretaries of DHEW, USD A, and USDI
(who in turn are expected to call on Federal, State and private ex-
perts for advice) would provide for Identification of essential uses
and assure that such approval will be based on sound judgment.
Abundant evidence proves the widespread distribution of DDT
and its metabolites (principally DDE) in man, birds, fish, other aqua-
tic organisms, wildlife, soil, water, sewage, rivers, lakes, oceans, and
air. Evidence also demonstrates that these materials are highly in-
jurious to some nontarget species and threaten other species and bio-
logical systems. Elimination of all nonessential uses should be achieved
and the period of 2 years is recommended to assure achievement with-
out excessive economic disruption.
Unavoidable residues of these persistent pesticides will continue
to occur in the soil, water, air, and food supplies for a period of years
despite restriction of usage in the United States. Reasonable methods
must be established for the use of as much of the food supply as
possible without hazard to human health.
Despite diminution of DDT usage, the Commission urges that
research be intensified to gain further understanding of the ecological
dynamics and public health implications of this example of a persist-
ent chemical widely distributed in the environment.
It should be recognized that DDT is used in developing nations
in the prevention and control of malaria, typhus, and other insect-
borne diseases, and in the production of food and fiber. The control
of such uses is the responsibility of those nations. They should, how-
ever, receive from the United States the full benefit of all available
information and assistance on hazards, safe and effective uses of
pesticides, and alternative methods of pest control.
Recommendation 4:
Restrict the usage of certain persistent pesticides in the United
States to specific essential uses which create no known hazard to human
health or to the quality of the environment and which are unanimously
approved by the Secretaries of the Departments of Health, Education,
and Welfare, Agriculture, and Interior.
Several pesticides other than DDT are persistent and cause or can
cause contamination of the environment and damage to various life
forms within it. These include aldrin, dieldrin, endrin, heptachlor,
chlordane, benzene hexachloride, lindane, and compounds containing
arsenic, lead, or mercury. We may anticipate that decreased use of
DDT and the above chemicals will result in an increased use of other
chemicals such astoxaphene. While there is no evidence that toxaphene
undergoes biological magnification, its chemical properties suggest
9
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that it should receive close surveillance. Furthermore, the use of or-
ganometallic compounds and salts of heavy metals other than arsenic,
lead, or mercury should be periodically reviewed.
The uses of persistent compounds should be fully reviewed in light
of recent advances in understanding the undesired effects of some
pesticides. The acceptable uses should be selected and approved
unanimously by the appropriate departments. Such usage should be
retricted to essential purposes, limited to the lowest effective dosage
required for the production and protection of essential foods and
fibers, and replaced by safer alternatives wherever possible.
It is, however, impractical to attempt to eliminate the residues
of such pesticides from foods by the application of zero tolerance
limits. Modern techniques have greatly increased the sensitivity of
the analytical methods available when the zero tolerance concept
was advanced. This fact must be recognized in judging the possibilities
of hazards and establishing tolerance limits with a sufficient margin
of safety to protect human health and welfare.
Recommendation 5:
Minimise human exposure to those pesticides considered to present
a potential health hazard to man.
Decisions on restriction of human exposure to pesticides should be
made by the Secretary of the Department of Health, Education, and
Welfare. In reaching such decisions, consideration must be given to
both the adequacy of the evidence of hazard to human health and pos-
sible consequences to human welfare that flow from the imposition of
restrictions on human exposure to pesticides.
Accordingly, it is of utmost importance that the results of screening
tests be scientifically and rationally considered. The correct interpreta-
tion of hazards to human health is sometimes extraordinarily difficult.
It must involve the transfer of the results of animal experiments to pre-
diction of human effects. In addition, the screening process frequently
involves preliminary examination of the effects of massive dosages, pos-
sible contamination of test samples, and other factors which affect
proper interpretation.
The health and welfare of the public must be effectively protected.
However, it is not in the best interest of the public to permit unduly
precipitate or excessively restrictive action based only on anxiety.
In recent screening studies in animals employing high dosage levels,
several compounds have been judged to be positive for tumor induc-
tion. In similar screening studies other pesticides have been judged
to be teratogenic. The evidence does not prove that these are injurious
to man, but does indicate: (1) A need to reexamine the registered uses
of the materials and other relevant data in order to institute prudent
10
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steps to minimize human exposure to these chemicals; and (2) to un-
dertake additional appropriate evaluatory research on representative
samples of these substances in order to guide future decisions. It is
further important to have detailed knowledge of sample composition
and purity. These materials are: aldrin; amitrol; aramite; avadex;
bis (2-chloroethyl) ether; chlorobenzilate; p,p'-DDT; dieldrin; hep-
tachlor (epoxide); mirex; n-(2-hydroxyethyl)-hydrazine; strobane;
captan; carbaryl; the butyl, isopropyl, and isooctyl esters of 2,4-D;
folpet; mercurials; PCNB; and2,4,5-T.
The imposition of restrictions on exposure, particularly from pesti-
cide residues in food and water, should be accompanied by periodic
review and adjustment of pesticide residue tolerances. Indiscrimi-
nate imposition of zero tolerances may well have disastrous conse-
quences upon the supply of essential food and threaten the welfare of
the entire Nation. Stepwise lowering of pesticide tolerance may in some
cases be an effective and flexible instrument with which to execute
policy.
Currently our national resources of funds, manpower, and facilities
will not permit the concurrent testing of all pesticidal compounds.
Priorities for testing must be established. Effective national implemen-
tation of this policy will require continuing development and evalua-
ton of scientific information concerning the hazards of pesticides to
human health. Additional chemicals are being or should be investi-
gated and evaluated for potential hazards to human health, as re-
sources permit.
Recommendation 6:
Create a pesticide advisory committee in the Department of Health,
Education, and Welfare to evaluate information on the hazards of
pesticides to human health and environmental quality and to advise
the Secretary on related matters.
The Secretary of the Department of Health, Education, and Wei*
fare is obligated to protect and enhance human health and welfare.
In relation to pesticides, this requires that he draw upon a wide
range of expert opinion and guidance. Excellent competence in some
areas exists within the staff of the Department, but the advisory serv-
ices of a group drawn from the professional, industrial and academic
specialists in related fields can provide unique and essential services.
A Pesticide Advisory Committee should be created and should in-
clude experts on human health and welfare, on environmental and
agricultural sciences, and from appropriate economic and industrial
areas of knowledge and experience.
In assisting the Secretary, the Pesticide Advisory Committee would:
• Intrepret new information from scientific sources and from in-
creased national experience with pesticides.
11
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• Assess the potential hazards of specific pesticides, based on
consideration of persistence of residues, possible distribution
and magnification in biological systems, and potential hazards
to human health and welfare.
• Recommend improvements in administrative procedures relat-
ing to pesticides; areas requiring intensified research atten-
tion ; adequate programs for monitoring and interpreting pesti-
cide distribution; and, in conjunction with the U.S. Depart-
ment of Agriculture and the U.S. Department of the Interior,
recommend educational and training programs designed to im-
prove usage of pesticides and reduce deleterious effects.
• Evaluate the complex risks and benefit considerations necessary
for making responsible judgments on the uses of pesticides, and
suggest means for maximizing benefits and minimizing risks.
• Provide advice on suitable standards and tolerances for pesticide
content in food, water, and air to protect the public health and
the quality of the environment.
• Identify gaps in knowledge and advise on needed research.
• Review and recommend test procedures and protocols to be
employed by manufacturers in establishing the safety of
pesticides.
The committee should receive the full benefit of the information and
professional competence present in the Department of Health, Educa-
tion, and Welfare, maintain strong liaison with any comparable
advisory groups in other Federal agencies, and have free access to
specialists and experts throughout the nation.
Recommendation 7:
Develop suitable standards for pesticide content in food, water, and
air and other aspects of environmental quality, that; (1) protect the
public from undue hazards, and (0) recognize the need for optimal
human nutrition and food supply.
In setting tolerances for pesticide residues in or on foods, the De-
partment of Health, Education, and Welfare should be cognizant
of the need for optimal human nutrition and food supply. Because
widespread environmental contamination by DDT and other persist-
ent pesticides can cause unavoidable residues in many raw foods,
the new Pesticide Advisory Committee should examine the problem
of tolerances carefully. Total human exposure, actual daily intake,
and total body burden of pesticide residues should be minimized when-
ever feasible, but unavoidable residues should be realistically con-
sidered. (See next recommendation).
There is need to abate widespread contamination of the environment
in order to reduce unavoidable residues of pesticides in food, water,
T2
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and air. Of equal importance is the need to take anticipatory regulatory
action to prevent future problems caused by other pesticides.
The fact that DDT residues are widespread throughout the environ-
ment has lead to unusual difficulties for certain food industries. For
example, the fact that DDT is concentrated from contaminated waters
into the fat of coho salmon and other fish is not the fault of the fishing
industry. DDT contamination of lakes, rivers, and oceans is not sus-
ceptible to immediate correction and reduction will require concerted
action to prevent DDT entry from various sources. Tolerances for
DDT residues in fish should be subjected to immediate review and
reflect the relative importance of the food in the diet. Concurrent
efforts should be made to apply processing methods capable of re-
ducing the DDT content of fish.
The Pesticide Advisory Committee may wish to consider a graded
series of regulatory actions developed in proportion to the extent of
environmental contamination or risk thereof, in relation to total human
exposure, actual daily intake, and total body burden of pesticide
residues. Such a series might be as follows:
Grade I: No significant environmental contamination or risk
thereof is judged to exist. Only periodic surveillance
and confirmatory evaluation is required.
Grade II: Some environmental contamination or risk thereof is
judged to exist. Active surveillance is required, in-
cluding the assessment of total human body burden
of pesticide residues; investigation of their relation-
ships to various sources; evaluation of reductions by
variations in food harvesting, processing, and dis-
tribution techniques; and routine regulatory controls.
Grade III: Substantial environmental contamination or risk
thereof is judged to exist. Restrict total usage with
active program of replacing present usage with alter-
native pesticides, and approve use by permit only.
Grade IV: Widespread or severe environmental contamination
or general risk thereof exists. Ban all nonessential
uses and remove from the general market. Approve
use by permit only.
If indicated by the best available evidence, the above-graded series
of regulatory actions would permit immediate classification of a pesti-
cide into grade III or IV, thus requiring approved use by permit only.
Anticipatory action can prevent harmful environmental contamina-
tion by pesticides and their movement into food, water, and air.
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Recommendation 8:
Seek modification of the Delaney clause to permit the Secretary of
the Department, of Health, Education, and Welfare to determine when
evidence of carcinogenesis justifies restrictive action concerning food
containing analytically detectable traces of chemicals.
The effect of the Delaney clause 2 is to require the removal from
interstate commerce of any food which contains analytically detectable
amounts of a food additive shown to be capable of inducing cancer in
experimental animals. This requirement would be excessively con-
servative if applied to foods containing unavoidable trace amounts
of pesticides shown to be capable of inducing cancer in experimental
animals when given in very high doses. If this clause were to be en-
forced for pesticide residues, it would outlaw most food of animal
origin including all meat, all dairy products (milk, butter, ice cream,
cheese, etc.), eggs, fowl, and fish. These foods presently contain and
will continue to contain for years, traces of DDT despite any restric-
tions imposed on pesticides. Removal of these foods would present a
far worse hazard to health than uncertain carcinogenic risk of these
trace amounts.
Commonly consumed foodstuffs contain detectable amounts of un-
avoidable naturally occurring constituents which under certain experi-
mental conditions are capable of inducing cancer in experimental ani-
mals. Yet, at the usual low level of intake of these constituents they are
regarded as presenting an acceptable risk to human health.
Exquisitely sensitive modern analytical techniques which became
available since enactment of the Delaney clause permit detection of
extremely small traces of chemicals at levels which may be biologically
insignificant. Positive response in carcinogenic testing has often been
shown to be dose-related, in that the carcinogenic response increases
with increasing dose levels of the carcinogen; when the dosage of a
carcinogen is minimized, the risk for cancer is also minimized or
eliminated.
The existence of such dose responses of carcinogens must be taken
into account by evaluating the balance of benefits and risks as is com-
monly done in assessing any toxic ehemica]. Ignorance concerning the
possible role of environmental chemicals in causation of human cancer
reinforces the case for caution in making such judgments. In addition
to the complexities of determining a "no effect" level of a weak car-
cinogen in a given experimental species, the extrapolation of the sub-
stance's effects to other species including man is of such intuitive na-
ture that a wide margin of safety must be allowed. Nevertheless,
compelling considerations of the increasing need for food may lead
3 Federal Food, Drug, anil Cosmetic Act, as amended, sec, 400 (c) (3) (A).
14
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to acceptance of ari undetectable small risk in order to obtain the
benefit of adequate food.
The recommendation for revision of the Delaney clause is made in.
order to permit determinations essential to the protection of human
health, not to justify irresponsible increases in the exposure of the
population to carcinogenic hazards.
Recommendation 9:
Establish a Department of Health, Education, and Welfare clearing-
house for -pesticide information and develop pcxticide protection team#.
The sources of information on pesticides are exertmely diverse and
scattered, including Federal and State agencies, universities, private
research centers, and industrial laboratories. The urgent problems of
pesticide management require rapid access to scientific information.
At the same time, a most serious information gap exists in the absence
of reliable sources of data on local activities, progress, and problems
throughout the Nation. Therefore, the establishment of a clearinghouse
for pesticides is recommended and the organization of pesticide pro-
tection teams is strongly urged.
The clearinghouse should:
• Collect and organize information on pesticides and their rela-
tionships to human health and the quality of the environment in
a modern system for storage, retrieval, and dissemination, and
secure evaluations of such data.
• Provide bibliographies, reprints, and summaries upon request
from the Secretary of the Department of Health, Education, and
Welfare, appropriate Federal and State agencies, research cen-
ters and others with a valid need for knowledge.
• Receive continuously information from the pesticide protection
teams and provide for its proper summary and distribution,
with special attention to dangers or improvements related to
methods of pest control.
• Maintain liaison with national and international bodies active
in the field of pesticide safety.
• Receive, summarize, and distribute data from pesticide monitor-
ing programs related to human health and welfare.
Pesticide protection teams should be developed from existing local
personnel and coordinated with Federal and State personnel and
facilities from agriculture, wildlife and public health. They would:
• Augment existing agricultural extension and fish and wildlife
efforts relating to pesticides and thereby guide local usage and
safeguards.
15
371-074 O—'69
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• Improve local surveillance of pesticide contamination, facili-
tate monitoring of human tissue residues of pesticides, and
investigate usage patterns and episodes of human toxicity.
• Provide a rapid flow of local information based on the above
activities, to and from the clearinghouse, especially concerning
any emergency related to pesticides.
• Inform the public, users of pesticides, local government and
enforcement agencies, and others in the proper and safe uses
of pesticides, techniques for disposal, and other matters.
• Stimulate local awareness and constructive concern essential
for optimal use of pesticides.
Recommendation 10:
Increase Federal support of research on all methods of pest control,
the effects of pesticides on human health and on the ecosystems, and
on improved techniques for prediction of human effects.
The scientific talent of the Nation should be mobilized more effec-
tively to resolve the problems associated with the control of pests.
This will require increased Federal support of intra- and extra-
mural research and development by all Departments concerned with
pesticides.
In order better to assess the toxic effects of pest control agents on
nontarget organisms and on human health, research should be ex-
panded relative to the metabolism and degradation of pesticides
and their effects 011 the integrated systems by which organisms de-
rive energy, build protoplasm, and reproduce. Additional studies
on teratogenesis, mutagenesis, and carcinogenesis must be supported.
Epidemiologic and pathologic relationships as may exist between
pesticides and hematologic, metabolic, neurologic, cardiovascular, and
pulmonary diseases, pregnancy losses, and cancer must be studied in
appropriate communities and population groups.
The nature and extent of any interactions that may exist between
pesticides and other factors in the environment require further elucida-
tion. Improved scientific methods and protocols should be developed
to assess dose-response and metabolic phenomena related to the bio-
logical effects of pest control chemicals in various species in order
to increase the accuracy of extrapolative predictions concerning human
effects.
The economic costs of pesticides should be evaluated. This should
include the hidden costs to man resulting from the uses of pesticides.
Accurate quantitative data on environmental contamination and
damage to nontarget species by pesticides should be obtained in order
to assess the impact of the total global burden of pesticide residues.
The Department of Agriculture undertakes to determine the economic
16
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impact of changes in pesticide usage, and such information should be
incorporated in this evaluation.
Cooperative Federal and State programs of research, training, and
demonstration aimed at the solution of practical pest control problems
should be expanded. The U.S. Department of Agriculture and the
Department of the Interior should make greater use of cooperative
agreements and grant support for these purposes. Such support would
lead to:
a. Better evaluation of the benefits of pesticides used for various
purposes in the context of alternative methods of pest control,
including combinations of pest control methods ;
b. Development of less hazardous pest control chemicals with
high target specificity and minimal environmental persistence;
c. Comprehension of the nontarget effects of pesticides; and
d. Reduced damage to the environment.
Recommendation 11:
Provide incentives to industry to encourage the development of
more specif/: pent control chem icals.
Incentives should be provided to industry to encourage the develop-
ment of safer chemicals with high target specificity, minimal environ-
mental persistence, and few, if any, side effects on nontarget species.
Developmental costs will be disproportionately high in relation to
profits from the lower volume of sales of more specific chemicals
which will be used selectively. The high cost of development will
discourage investments unless incentives are provided.
In order to encourage joint developmental efforts by Government
and industry, consideration should be given to the applicability of the
present patent laws and practices. The working life of a patent is in
effect shortened by the extended period required to secure approval
and registration. Moreover, the assignment of patents to public owner-
ship rather than to licensees reduces the incentive for private enter-
prise to undertake the financial burden of approval and registration.
Recommendation 12:
Review and consider the adequacy of legislation and regulation
designed to:
1. Improve the effectiveness of labeling and instructions to users.
a. Advertising inconsistent with the label should be
prohibited.
b. An entirely new scheme of denoting relative toxicity
should be devised. The average consumer does not under-
stand the progression from caution, to warning, to poi-
son. A need exists for a nonlanguage (graphic or numeri-
17
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cal) representation of oral inhalation and dermal toxicity
to enable consumers to select less hazardous materials.
c. Effective labeling practices and instructions to users re-
quire use of common (generic) names for all pesticides,
and the conveying of clear directions for and information
about proper use, dangers, and first aid. Printing should
be readable and multilingual when that is appropriate.
d. When the chemical is known to be especially hazardous
to some type of organism, as toxaphene is for fish, this
should be stated.
e. Instructions should also offer clear directions for safe
disposal of the empty container and of any unused
material.
2. Extend the present concept of experimental permits as a mech-
anism to register pesticides initially on a restricted basis to
enable close observation, documentation, and reassessment of
direct and indirect effects under conditions of practical usage.
3. Improve packaging and transportation practices in order to
minimize dangers of spillage and the contamination of ve-
hicles and of other merchandise.
4. Provide for monitoring and control of effluents from plants
manufacturing, formulating, and using pesticides.
5. Provide uniform indemnification to parties injured by mis-
takes in pesticide regulatory actions by Federal and State
authorities.
Recommendation 13:
Develop, in consultation with the Council of State Governments,
model regulations for the collection and disposal of unused pesticides,
used containers, and other pesticide contaminated materials.
The current model pesticide law recommended by the Association
of American Pesticide Control officials does not cover the important
problems of disposal of surplus pesticides and of used pesticide con-
tainers. Kegulations to control these important sources of contamina-
tion and of accidental poisonings properly belong in State or local
codes.
An additional feature that should be included in a model law is
registration, possibly by social security number, of all workers em-
ployed in manufacturing or applying especially hazardous pesticides.
This would facilitate implementation of measures to protect them
from hazardous exposures as well as to expedite epidemiological in-
vestigation of adverse effects of pesticides on human health.
18
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Recommendation 14:
Increase participation in international cooperative efforts to promote
wfe and effective mage of pesticides.
DDT is widely distributed throughout the global environment.
If present usage patterns continue, or if other persistent pesticides are
used in large quantities, the contamination of the environment may
increase with time. An international problem exists and it will require
international cooperation to solve it.
Government and industry should increase their participation in
international cooperative efforts to assist developing nations to promote
safe and effective usage of pesticides for disease prevention and the
production of essential foods and fibers. The risk-benefit considera-
tions differ somewhat from country to country depending on the
particular problems encountered. Both benefits and hazards of using
a pesticide must be evaluated carefully in order to determine the appro-
priateness of use in a given area.
The U.S. Government should assume leadership in studying the
inherent health hazards of pesticide usage and cooperate in the training
of technical personnel from other countries.
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SUMMARIES OF SUBCOMMITTEE
REPORTS
USES AND BENEFITS OF PESTICIDES
Summary and Conclusions
The production and use of pesticides in the United States is expected
to continue to grow at an annual rate of approximately 15 percent.
Predictions are that insecticides will more than double in use by
1975 and herbicides will increase at an even more accelerated pace.
The foreign use of pesticides will likewise continue to increase with
the organochlorine and organophosphorous insecticides continuing to
represent a significant part of the foreign market.
The use of DDT in domestic pest control programs is rapidly de-
clining with the major need reported to be associated with cotton
production in the Southeastern United States. Although the total
production is declining, an increasing quantity is being purchased by
AID and UNICEF for foreign malaria programs.
Most other persistent pesticides have continued to decline in use
since 1957, a trend that will continue with the remaining uses being
primarily nonagricultural. The shift to nonpersistent pesticides will
continue at an accelerated rate, however, there will be a continued
need for use of persistent materials for the control of selected pest
problems.
Although imaginative and exciting research is in progress, non-
insecticidal control techniques are not likely to have a significant
impact on the use of insecticides in the foreseeable future. There is
evidence of an increased appreciation for the use of integrated con-
trol in the management of pest populations with less persistent and
more selective insecticides playing an important part.
There is a serious lack of information available on pesticide use
patterns, particularly as they relate to nonagricultural uses. Likewise,
available data are usually not obtainable for a proper evaluation of
the economic implications of pesticide use. The United States activity
in international pest control programs is complicated by the magnitude
21
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of involvement and the complexity of diplomatic and agency respon-
sibilities. There are many factors that are influencing the changing
use patterns of pesticides. In addition to new pest infestations, resist-
ance to selected pesticides, alterations in the economics of crop pro-
duction, and changing agricultural and social patterns, the impact of
public opinion is having a growing influence on the use of pesticides.
The increased concern for new legislation and regulation of the
manufacture, sale, and use of pesticides must not be so structured
as to destroy the incentive for development of new pesticides more
compatible with other desirable environmental qualities.
CONTAMINATION
Summary and Conclusions
The subgroup on contamination has examined the present status of
knowledge on the dissemination of pesticides into the environment, the
mechanisms and rates at which they accumulate in various elements
of the environment, and methods by which pesticides might be con-
trolled so that their presence in the environment would pose a minimal
hazard to society consistent with the benefits to be obtained from
their use.
The subgroup has examined: a) The air route by which pesticides
are applied and distributed in the biosphere; b) the water route;
c) the food route; d) soil contamination; e) household uses of pes-
ticides; f) occupational exposures resulting from the manufacture
and application of pesticides, and accidents that may occur in their
use; g) alternatives to the use of persistent pesticides; h) the monitor-
ing of pesticides in the environment; i) systems analysis of pesticides
in the environment.
Much contamination and damage results from the indiscriminate,
uncontrolled, unmonitored and excessive use of pesticides, often in
situations where properly supervised application of pesticides would
confine them to target areas and organisms and at the concentrations
necessary for their beneficial use without damage to the environment.
Research investigations, demonstrations, and monitored operations
reveal that the careful application of many of the pesticides and the
use of techniques presently available and being developed can be
expected to reduce contamination of the environment to a small frac-
tion of the current level without reducing effective control of the target
organisms.
The present piecemeal involvement of various Federal agencies in
pesticide control requires more than the existing type of coordination.
22
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As human health and welfare are the values of prime concern, the
DHEW should provide a lead in the establishment of a mechanism
for administering pesticide control programs.
Ad hoe studies of pesticides in the environment are not adequate to
assess the inputs of pesticides to the biosphere, their degradation,
translocation, movement and rates of accumulation. Monitoring is con-
ducted by a large number of agencies, but in each instance the monitor-
ing is related to a specific mission of the agency. Therefore, a single
agency should take the initiative to insure the effective monitoring
of the total environment, and the filling of gaps in data such as for
oceans and ground water, as they are identified. A continuous systems
analysis of pesticides in the environment needs to be conducted.
Aerial spraying should bo confined to specific conditions of lapse
and wind that will preclude drift. Regulations to limit aerial applica-
tion to specific weather conditions would be helpful in providing
guidance for regulatory programs. Increased engineering development
effort is needed for the design of equipment for, and the adaptation
of helicopters to the aerial spraying of pesticides.
The use of low volume concentrated sprays should be encouraged.
Since this technique, if it is not properly controlled, can be more haz-
ardous to workers, effective regulations must precede its increased use.
Increased information is needed on the degree of exposure of the
general population to pesticides used for household, lawn, and garden-
ing purposes. More effective means for regulation and control of pesti-
cide use by the general public should be instituted, possibly by licensing
of distribution outlets.
The use of lindane and similarly toxic materials which act by evapo-
ration must be discontinued where humans or foods are subject to
exposure, such as in homes, restaurants, and schools.
There is a vastly increased need for the education of the general
public in the management of pesticides and in the training of profes-
sional applicators. Public communications media, schools and univer-
sities all have important roles to play.
Labeling regulations must also be improved. Print should be en-
larged and language should be made intelligible for the lay public.
A need exists for nonlanguage, internationally intelligible insignia or
markings that will advise the user of the degree of toxicity and per-
sistancc of the product, its method of application, and the target
organisms.
More vigorous effort is needed to replace the persistent, toxic, and
broad-spectrum pesticides with chemicals that are less persistent and
more specific. Certain of the less-persistent pesticides, however, may
be more toxic to humans and therefore effective regulation of their
application is required to insure against injury to personnel.
23
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Integrated control techniques for the control of select pests promises
to effect n reduced usage of pesticides. Such alternative techniques
should be more widely applied.
Licensing of commercial pesticide applicators, as well as other large-
scale applicators of hazardous materials should be required.
Analytical methods, although extremely good, require further de-
velopment. Need exists for standardizing or referencing additional
techniques, even on an international basis. There is need for both
less sophisticated techniques for field use as well as for automated
techniques for wide-scale monitoring.
Standards for selected pesticides should be included in the Public
Health Service "Drinking Water Standards". Although guidelines
and criteria for some pesticides have been delineated, they have never
been officially established.
Prior to application of pesticides to waters for the control of -weeds,
snails, mosquitoes, and in other aquatic uses, a careful analysis should
be made of the proposed pesticide characteristics with respect to the
uses of the target area. Special concern is indicated where domestic
water supply is involved, or where food-chain concentration may
occur.
Steps should be taken to prevent the simultaneous shipment of
pesticides and foodstuffs within the same vehicle. Comprehensive
regulations for pesticide transportation are required.
Safe methods of disposal of pesticides, their wastes, and containers
are needed to prevent the contaimination of the environment and to
protect individuals from contamination and accidents.
Intensified research and development is needed in the following
areas, among others:
~. Prediction of the micrometeorological conditions suitable
for aerial spraying.
~. Application of systems analysis to the pesticide-enviromcnt
problem.
c. Pesticide chemodynamics, with emphasis on reservoirs of
storage.
d. More intensive development of less-persistent pesticides
with narrow spectra of toxicity.
e. Continuing development of spray devices with narrow
spectra of droplet sizes.
/. Continuing development of alternatives to chemical control
of pests.
g. Creation of more suitable materials for pesticide packaging
and containers to facilitate safe transfer, handling use, and
disposal.
24
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h. Treatment processes for the elimination of pesticides from
domestic water supplies as well as from wastewaters.
i. Immediate studios of the effects of pesticide residues on
ftlgal photosynthctic activity.
EFFECTS ON NONTARGET ORGANISMS OTHER
THAN MAN
Summary and conclusions
Man is an integral part of the living system, which includes about
200,000 species in the United States- Most of these are considered to
he essential to the well-being of man. Pesticides are now affecting indi-
viduals, populations, and communities of natural organisms. Some,
especially the persistent insecticidal chemicals such as DDT, have re-
duced the reproduction and survival of nontarget species.
Pesticides are dispersed via air, water, and the movements of organ-
isms. The most significant concentrations are found in and near the
areas of intensive use, but traces have been found in the Antarctic and
other ureas far from application. Pesticides have reduced the popula-
tions of several wild species. Both extensive field data and the results
of excellent controlled experiments demonstrate that certain birds,
fishes, and insects are especially vulnerable. There are suggestions that
pesticides in the environment may adversely affect processes as funda-
mental to the biosphere as photosynthesis in the oceans.
However, the scarcity of information concerning the influences of
pesticides on natural populations prevents adequate assessment of
their total effects. Less than 1 percent of the species in the United
States have been studied in this connection, and very few of these
have been subjected to adequate observation. Present methods and pro-
grams for determining the influences of pesticides on nontarget organ-
isms are inadequate. Little data exists on the distribution, location, and
impact of various pest control chemicals in the natural living systems
of the world.
The general nature of the effects of pesticides on nontarget species
populations and communities can now be suggested. Although there
is usually greater similarity of reaction between closely related species,
each species reacts differently to specific pesticides. DDT, for example,
causes egg shell thinning in ducks and falcons, but not in pheasants
and quail. Pesticides from the air, water, and soil may be concentrated
in the bodies of organisms. The concentrating effect is frequently en-
hanced as one species feeds on another and passes the pesticide from
one link to another in the food chain. Hence, predators like some birds
25
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.and fish may be exposed to levels several thousand times the concen-
tration in the physical environment. Some nontarget organisms can,
under highly selective pressure from pesticides, evolve resistance to
them. The surviving resistant individuals may pass extremely high
concentrations to their predators. In communities exposed to pesticides,
the total number of species is usually reduced and the stability of popu-
lations within the community is upset. Often, beneficial species are
unintentionally eliminated. Such a reduction in the number of species
is frequently followed by outbreaks or population explosions in some
of the surviving species, usually those in the lower parts of the food
chain. When a vital link low in the food chain is eliminated, many
predators and parasites higher in the food chain are often also
destroyed.
The Committee has reached the following conclusions:
1. Adequate methods should be developed and utilized for evalu-
ation of the hidden costs of the uses of pesticides.
Such evaluation is essential as part of the development of use-
ful estimates of all of the benefits and costs to society. Some
partial estimates of the direct benefits are available and useful.
Adequate data are not available on such indirect costs as losses
of useful fish and wildlife, damage to other species, and any
esthetic effects. These are required to guide rational decisions
on the proper uses and control of pesticides so that the net gains
will be as great as possible while the net losses are minimal.
2. Persistent chlorinated hydrocarbons which have a broad spec-
trum of biological effects, including DDT, DDD, aldrin, chlordane,
dieldrin, endrin, heptachlor, and toxaphene, should be progressively
removed from general use over the next 2 years.
These pesticides are causing serious damage to certain birds,
fish, and other nontarget species among world populations.
Some of these species are useful to man for food or recreation,
some are essential to the biological systems of which he is a part,
and some merit special protection because they are already
endangered.
These pesticides have value in specific circumstances, and
we suggest that they be used only under license and with spe-
cial permits. The system for assuring this careful use should
be established as the unrestricted use of these materials is
phased out over the 2-year period.
I). The release of biocidal materials into the environment should
be drastically reduced.
26
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In addition to restriction of tlie use of hazardous pesticides,
many techniques can be applied which will minimize the re-
lease of pest, control chemicals. In industry, improved chem-
ical and engineering processes could reduce the quantity of
contaminated wash water; more effective methods can be
developed for disposal of unused stocks and residues of pesti-
cides; and improved surveillance of effluents would be de-
sirable. For home use, improved materials and methods of
application can be created and employed with greater discre-
tion on the part of the individuals involved. For large-scale
applications, conversion to integrated methods of pest control,
care in the selection and application of specific chemicals, and
preference for short-lived pesticides would reduce release to
the environment.
These efforts, combined with increased research and educa-
tion, would slowly but effectively reduce the damage to non-
target species.
4. The U. S. Department of Health, Education, and Welfare
or another Federal agency should negotiate a contract with a suitable
national professional organization to develop a system, complete
with standards of training, testing, and enforcement, for the effective
restriction of use of selected pesticides known to be especially haz-
ardous to man or to elements of the environment.
To achieve an adequate and prompt further reduction in
the use of certain pesticides and still permit their use where
no adequate substitute is acceptable, there must be a system
of regulation based upon State or local authority but using
uniform national standards. This system should provide for
use of the selected pesticides only by or under the immediate
supervision of a licensed operator meeting certain standards
of training, competence, and ethics.
5. Educational efforts relating to the proper and improper usages
of pesticides should be improved and expanded.
The most important element in the wise use of pesticides
is the individual person who selects the chemical to be used and
decides upon the methods of application. Suggestions have
been provided elsewhere for the proper training of all large-
scale applicators. It is equally important that homeowners,
gardeners, students, legislators, civic officials, and others receive
adequate and correct information and develop proper atti-
tudes. Such education could contribute greatly to wise use of
pesticides, and also to rational response to governmental efforts
27
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to protect public health and welfare while graining as much
advantage as possible from pest control methods.
6. All pertinent Federal and State agencies should review and
improve policies suid practices of pesticide use.
The beneficial uses of pesticides have been accompanied by
a wide variety of policies and practices which have sometimes
been wasteful, unnecessarily destructive, or ineffective. We
offer the following suggestions to be included among the guide-
lines for wise use of pesticides:
a. Pesticides should be applied only when there is evidence
that pest densities will reach a significant damage threshold.
b. Effective pest control does not usually require eradication
of the j^est species, and should be directed toward optimal
management of pest densities.
c. Support for research and demonstrations should be pro-
vided to projects based on the systems approach to pest manage-
ment and control.
d. Diversity of species is biologically desirable since it con-
tributes to the stability and efficiency of life systems.
e. No species should be eradicated except as a carefully se-
lected i>est and when compensating human gains are ecologicalty
sound and clearly established.
f. Special care must be taken to prevent any damage to the
species and mechanisms which are of fundamental importance
to biological systems. For example, oceanic phytoplankton pro-
duces most of the oxygen necessary for the earth's biological
system.
g. Requirements for food quality should not be so high as to
require excessive use of pesticides. Customer preference, and
regulatory requirements, for unblemished fruit and vegetables
and the complete absence of insect parts have encouraged heavy
use of pesticides.
h. New pesticides should be given interim approval which
permits contained use in limited but typical circumstances
prior to general approval. The pattern of careful progressive
risks would encourage new developments without endangering
the public interest.
i. Effective incentives should be established to encourage the
development of improved pest control techniques. The cost of
entering a new product or test ing a different control technique is
high. Since effects on the national welfare are involved, proper
governmental encouragement of private industrial efforts may
be appropriate.
28
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7. Registration requirements should be strengthened and rede-
signed to permit initial provisional approval, then general use ap-
proval, and to require periodic review and re-registration of materials.
Registration of pesticides offers the most important oppor-
tunity for estimating potential benefits and costs in advance
of wide usage. In addition to present registration application
information, useful estimates should be provided of the per-
sistence of the pesticide, on the breadth of its biological impact,
and on its fate. These will disclose the nature and possible mag-
nitude of the nontarget effects. If approval is appropriate, we
suggest that it be for a short-term period and for use under
defined circumstances where risks are confined, and that general
use be considered after such field experience. Since some of the
significant effects in nontarget species are subtle, sublethal, and
difficult to detect, we recommend that all pesticides be subject
to periodic review and approval.
8. All commercial applications and other large-scale applications
of pesticides should be performed under the supervision of competent
trained persons.
The complex responsibilities of pesticide application involve
both achievement of the greatest possible benefit and maximum
prevention of damage. These require considerable knowledge of
the management of crops, the biology of desirable and unde-
sirable species, the effects of weather, and the effects of biocidc
in the ecosystems. They also require application of professional
judgment and use of professional standards of conduct and
responsibility. We suggest that all such applicators should be
properly trained, required to demonstrate their competence, and
awarded evidence of their ability. Incentives in the forms of
salary and recognition will be needed to encourage such pro-
fessional training.
Training programs for pest management specialists of all
types, including applicators, should include the concepts of sys-
tems approaches to pest control and emphasize the relationships
between pest management activities and the total biological
community affected.
Since new information is emerging rapidly in pest manage-
ment, refresher courses for county agricultural agents, appli-
cators and others involved in the uses of pesticides and other
control techniques would be of special value,
9. The production of additional information and comprehension
should be encouraged and supported on many aspects of pesticide use
and effects.
29
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Experience with pesticides has revealed many serious gaps in
available knowledge. Research is urgently needed on many gen-
eral and specific problems. The following problems are all re-
lated to nontarget effects of pesticides, and many of them are
also pertinent to other areas of pesticide use, to successful man-
agement of animals and plants, and to fundamental science.
a. What are the acute effects of the common pesticides when
used on the many species of wildlife and other organisms which
may be exposed to them (
b. What are the effects of indirect and chronic exposure ?
c. What is the nature and magnitude of the effects of insecti-
cides on beneficial insects and other species ?
d. What are the normal patterns and variations in natural
biotic communities, as baselines for understanding future pesti-
cide pollution effects!
e. What mechanisms exert natural control on various pest
populations ?
f. How can we best estimate pest populations and predict,
their trends?
g. What are the full potentials and realistic limitations of the
pest control methods which are suggested as alternatives to
chemical pesticides, including predators, parasites, pathogens,
cultural control, sterilization, attractants, repellants, genetic
manipulation, and integrated approaches ?
h. What improvements are possible for pesticide packaging
and disposal (including degradable containers) to minimize
threats to nontarget species?
10. A vigorous specific program should be created to bring the 100
most serious insect pest species of the United States under optimal
control.
These require about_80 percent of the insecticides now in use.
Dramatic focusing of attention on the "100 worst*' could lead to
rapid improvement in the species-specific insecticides, bio-
logical control methods, or integrated control programs.
11. The responsibilities of the several Federal agencies involved
in pesticide regulation and control must be more clearly defined and
certain specific activities should be improved or initiated by appro-
priate agencies.
Procedures and patterns for the regulation and control of
pesticide use have emerged during the last 30 years in response
to changes in law, evolving practices in agriculture, production
of new chemical materials, changing public concern with health
30
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effects and nontarget damage, emerging scientific comprehen-
sion of benefits and costs, and other unstructured events. Both
benefits and costs are now so large as to merit the national allo-
cation of responsibilities. We suggest careful review and
reassignment, by law if necessary, of the proper role of—
a. The Department of Interior, charged with protection and
enhancement of nonagricultural resources and with water
quality control.
b. The Department of Agriculture, charged with assisting in
the maximum production of food, fibers, and other culturable
crops in ways which are not detrimental to other interests.
c. The Department of Health, Education, and Welfare,
charged with protection and improvement of human health and
welfare.
d. The National Science Foundation, responsible for im-
proved comprehension of fundamental processes and assisting
in their application for human benefit.
e. The Environmental Quality Council, Federal Committee
on Pest Control, and other coordinating agencies.
Other agencies are, of course, involved as users of pesticides
and in other functions. Those listed above, however, appear
to comprise the areas of primary attention. In addition to pres-
ent programs and activities related to pesticides, we suggest
the following services for new or additional emphasis:
a. A taxonomic and identification service should be estab-
lished to provide increased knowledge and reference standards
for biological investigations related to all fields of pest control.
b. Broader monitoring should be undertaken of the types
and quantities of pesticide transmitted by various means and
reaching nontarget species. Bioaccumulators like oysters and
other molluscs can be unusually useful as indicators, and the
levels of concentrations in predatory species are of special
importance.
c. Early indications of undesirable effects must be detected
effectively and followed by appropriate action. When the early
warning system suggests a potential pollution hazard in the
environment, the acquisition of additional pertinent informa-
tion by the scientific community should be supported.
d. Multidisciplinary investigations of alternative control
techniques should be carried out whenever present control meth-
ods are shown to contain potential hazards.
e. A single agency should assume the responsibility for
assimilating information on the effects of pesticides on nontar-
3!
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get species and transmitting it to appropriate regulatory and
educational centers.
f. Measurable predictors of potential hazards from pesti-
cide use should be agreed upon and might be made the basis
of a handicap tax to be applied to each pesticide in proportion
to its pollution hazard.
EFFECTS OF PESTICIDES ON MAN
Summary and Conclusions
The scope of this report is intended to encompass the present state
of knowledge concerning the nature, extent and consequences of hu-
man exposure to pesticides. Data relating to exposure of experimental
animals have been reviewed only insofar as they contribute to our
understanding of phenomena encountered in man or provide knowl-
edge in areas where human data are meager or totally lacking.
No human activity is entirely without risk and this maxim holds
for pesticide usage in the human environment just as it does for all
other exposure to chemicals. There are formidable inherent difficulties
in fully evaluating the risks to human health consequent upon the use
of pesticides. In part, these difficulties stem from the complex nature
of the problems involved, the fact that many facets of these problems
have been recognized only recently, and the general backwardness in
this area of research in man, as distinct from work in laboratory ani-
mals. Above all, one must not lose sight of the large number of human
variables—such as age, sex, race, socio-economic status, diet, state of
health—all of which can conceivably, or actually do, profoundly af-
fect human response to pesticides. As yet, little is known about the
effects of these variables in practice. Finally, one must realize that the
components of the total environment of man interact in various subtle
ways, so that the long-term effects of low-level exposure to one pesti-
cide are greatly influenced by universal concomitant exposure to other
pesticides as well as to chemicals such as those in air, water, food and
drugs. While all scientists engaged in this field desire simple clear-
cut answers to the questions posed by human exposure to pesticides,
the complexity of the human environmental situation seldom allows
such answers to be obtained. Attempts to extrapolate from the results
of animal experiments to man are also beset with pitfalls. Hence, the
greatest care needs to be exercised in drawing conclusions regarding
cause-and-effect relationships in human pesticide exposure.
The available evidence concerning such human exposure to pesti-
cides derives from three main sources: planned and controlledadmin-
32
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istration of pesticides to human subjects; case reports of episodes of
accidental or other acute poisoning; and epidemiological studies,
which in turn comprise surveys of occupationally-exposed groups (in
accordance with a variety of retrospective and prospective ap-
proaches) , and studies of the general population.
Indices of exposure of human beings to pesticides constitute a vital
link in the chain of evidence that must be forged in order to reveal,
interpret, and maintain effective surveillance of, pesticide exposures.
Hitherto, the view that, exposure of the general population was pre-
dominantly associated with the presence of pesticide residues in food
has been reflected in the efficient monitoring of total diet samples and
individual foods, but only sporadic attention to other sources of ex-
posure. It is now evident that much can be learned by monitoring the
end-product of human exposure in the form of pesticide levels in body
fluids and tissues of people. The information thus obtained is quite
distinct from, and at least as valuable as, the data on residues in food;
the two types of data complement each other admirably. Provision
of information on human levels, in adequately detailed coverage of
various groups within the general population is seen as the single
most immediate step towards a better understanding and surveillance
of total exposure from all sources of pesticides.
Sophistication achieved through the use of modern techniques has
made possible the study of absorption, disposition, metabolism and
excretion of some pesticides in man. Experience derived from animal
studies has provided guidance in directing the appropriate procedures
to the investigation of the behavior of pesticides in the human body.
To date, the most significant information of this sort relates mainly to
two organoehlorine pesticide groups, namely DDT and allied com-
pounds as well as the aldrin-dieldrin group. Knowledge of the dy-
namic aspects of the behavior of these two pesticide groups in the
human body is far from complete, but already some important facts
have been established. In general, for any given level of pesticide in-
take, an equilibrium level of pesticide is attained in blood and body
fat, despite continuing exposure. The precise concentration at which
the plateau is established is directly related to the level of exposure
but also to other determining factors. In the case of aldrin-dieldrin,
the blood level appears to l>e a reliable measure of exposure. It appears
further, that DDT in blood is directly related to recent exposure, while
in contrast DDE in blood is a reflection of long term exposure.
A detailed survey of case reports of incidents involving accidental
poisoning by organochlorine pesticides reveals that their general ac-
tion is to increase the excitability of the nervous system. Some of these
compounds also damage the liver. Their capacity to penetrate intact
human skin varies from one compound to aftother; in the case of en-
33
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drin, for example, percutaneous penetration plays an important part
in clinical intoxication. Within the organochlorine group of com-
pounds there is a wide range of potential for acute toxicity: DDT is
relatively safe in terms of acute intoxication, while di el drin and endrin
have produced many cases of serious poisoning. Lindane presents a
special problem, inasmuch as it lias been implicated, largely on the
basis of circumstantial evidence, in the causation of hematological
disorders. A characteristic of organochlorine poisoning is the dif-
ficulty of establishing the correct diagnosis. This is especially true in
cases of mild poisoning that result in nonspecific symptoms and signs,
since except in the case of dieldrin there are no established criteria for
diagnosis on the basis of blood levels. Specific therapeutic measures
do not exist.
Inhibition of cholinesterase enzymes by the organophosphate pesti-
cides appears to be the only important manifestation of acute or
chronic toxicity produced by this class of compounds. Great variation
in acute toxicity from one compound to another characterizes this
group, which includes some of the most toxic materials used by man.
Cholinesterase inhibition results in a well-defined clinical pattern of
intoxication which can be readily diagnosed. Specific therapeutic
measures are available and, provided they are pressed with sufficient
speed and vigor, are highly effective. Skin penetration by organophos-
phates may be substantial. In view of the toxic potential of these com-
pounds, protection of workers exposed to them assumes utmost impor-
tance. Protective measures should include education, training, proper
equipment design, suitable personal protection devices, careful medical
surveillance and well-organized facilities ready to treat cases of poison-
ing with a minimum of delay.
Carbamate pesticides are also cholinesterase inhibitors but, because
of rapid in vitro reactivation of the enzyme, measurement of cholines-
terase activity is not a reliable guide to exposure. As with organo-
phosphates, the toxic potential of some members of the carbamate
group is very great.
Controlled exposure of human volunteers to pesticides under close
medical supervision constitutes the most reliable approach to the
unequivocal evaluation of long-term effects of low levels of pesticide
exposure. The difficulties involved in maintaining such studies have
inevitably resulted in very small groups of subjects being exposed for
any appreciable length of time. The longest studies on record have
lasted less than four years and the results can only reflect the period
of study. Consequently, the findings, especially when they are negative,
are open to question when taken by themselves. It appears, however,
that present levels of exposure to DDT among the general population
have not produced any observable adverse effect in controlled studies
34
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on volunteers. The same is true of aldrin-dieldrin. These findings ac-
quire greater force when combined with observations on other groups,
such as occupa ti on ally -exposed persons.
With organophosphate pesticides, the problem, of human residues
does not arise "because these compounds are not stored in body fat.
Here the risk is one of acute poisoning. Much accidental poisoning is
attributable to public ignorance of the toxicity of these chemieals and
neglect of appropriate precautions in their use and storage. In de-
veloping countries serious accidents result from storage of pesticides
in unlabeled bottles and of food in used pesticide containers. Epi-
demics of acute poisoning follow spillage of concentrated organophos-
phates into bulk food or water sources. The hazard to human life is
shared by fish and wildlife. Regional pesticide protection teams are
suggested as a means of investigating, recording and ultimately pre-
venting accidents of this sort.
Industry has made much progress towards safe handling of pesti-
cides. Nonetheless, a very real occupational hazard exists, and exten-
sion of preventive measures should include regular blood testing for
evidence of organophosphate exposure. A limit for DDT and other
organochlorine pesticides in blood should be established to prevent
overexposure.
Pesticide exposure experienced by the population at large is in part
the legacy of earlier excessi ve or in j udicious use of persistent pesticides.
Residues of these compounds have been, and are still being acquired
from all articles of diet and a variety of other environmental sources.
This is the major source of public concern. Although a number of per-
sistent pesticides can be identified, attention is centered on DDT,
and closely-related compounds, the most ubiquitous and predominant
of all pesticide residues in man. The consequences of these prolonged
exposures on human health cannot be fully elucidated at present. Evi-
dence from workers who are subject to vastly greater exposure than the
public is reassuring but far from complete. Animal experiments clarify
certain issues but the results cannot be extrapolated directly to man.
On the basis of present knowledge, the only unequivocal consequece of
long-term exposure to persistent pesticides, at the levels encountered
by the general population, is the acquisition of residues in tissues and
body fluids. No reliable study has revealed a causal association between
the presence of these residues and human disease.
Despite such reassurance, realization of the paucity of our knowl-
edge in this area flows from increasingly sophisticated studies on hu-
man residues of DDT and related compounds. There appears to be
marked geographical stratification of DDT residues in our population,
the average levels in the cooler isotherms being one-half of those in
35
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the warmer climates. None of these observations apply to residues of
die-ldrin. Such finding cast serious doubt on accepted beliefs that
food is the predominant source of DDT residues and that the entire
general population has reached equilibrium as regards acquisition of
such I'esidues.
Reopening these questions emphasizes the inadequacy of present
monitoring of exposure by relying mainly on analysis of food. This as-
pect was stressed above. It also renders more urgent the need to con-
tain and eventually greatly reduce the extent of human and animal
contamination by pesticide residues. Existing knowledge confirms the
feasibility of inducing active withdrawal of pesticide residues from the
human body but further research to achieve a practical means of at-
taining this goal is needed.
A survey of the reported effects of pesticides on laboratory animals
has furnished information on factors and experimental conditions
that could not easily be reproduced in human studies. For example,
the influence of diet on pesticide toxicity, and particularly lack of
dietary protein, has revealed substantial increases in acute toxicity
of some pesticides. In this, as in some other sections of our report ref-
erence is made to the capacity of organochlorine pesticides to bring
about a great increase in the activity of liver enzymes responsible for
the metabolism of foreign compounds. This phenomenon of enzyme in-
duction has been extensively studied in animals and is discussed in de-
tail in the report of the Panel on Interactions. Comparable enzyme in-
duction in the human liver is brought about by many drugs and also by
DDT, It is a sad comment on the dearth of knowledge of human physi -
ology to point out that the threshold dose of DDT for induction of
metabolizing enzymes in human liver is unknown.
Special sections of the report deal with the possible effects of pesti-
cides in bringing about heritable alterations in the genetic material
(mutagenesis), effects on reproduction, including malformations in the
fetus or newborn infant (teratogenesis) and increasing the incidence
of various forms of cancer (carcinogenesis). The data available relate
only to experimental animals or to lower forms of life. At the present
time we do not know whether or not such results are applicable to
man. While there is no evidence to indicate that pesticides presently
in use actually cause carcinogenic or teratogenic effects in man, never-
theless, the fact that some pesticides cause these effects in experimental
mammals indicates cause for concern and careful evaluation. It is pru-
dent to minimize human exposure to substances producing these ad-
verse effects in mammals while additional investigations are under-
taken to assess the potential of such suspect pesticides for causing ad-
verse effects in man. There is a need to develop standard protocols
36
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for safety evaluation that are sufficiently flexible to permit an individ-
ual approach to the particular and often unique problems presented
by each pesticide. Assurance of safety to man demands special tech-
niques, not only for extrapolation of animal data to man, but also for
evaluation of controlled human expsure. Much effort will be required
to attain these objectives. Research in these areas should be expanded
and imbued with a greater sense of urgency than that manifested
before.
The Panel on Interactions has provided a valuable analysis of the
manner in which pesticides can interact with one another, and with
drugs and other environmental agents, in exercising effects on man
and animals. Once again one is struck by the complexity and impor-
tance of these interrelationships and by the extent of our ignorance of
effects on man.
To sum up, the field of pesticide toxicology exemplifies the absurdity
of a situation in which 200 million Americans are undergoing life-
long exposure, yet our knowledge of what is happening to them is at
best fragmentary and for the most part indirect and inferential.
While there is little ground for forebodings of disaster, there is even
less for complacency. The proper study of mankind is man. It is
to this study that we should address ourselves without delay.
37
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Part II
Subcommittee and Panel Reports
to the Commission on Pesticides
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CHAPTER 1
Uses and Benefits of Pesticides
Contents
Page
Summary and conclusions 43
General history of pesticides 44
Pesticides production and use 46
Factors influencing changing use patterns 58
Pesticide groups and general uses 61
Belated materials and their uses 73
Legislation and regulation relating to pesticide production and
use 75
Problems of introduction of new pesticides 78
Advantages and disadvantages of substitute methods of pest
control 80
Appendix—international aspects of pest control by chlorinated
hydrocarbons 83
Selected bibliography - 92
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USES AND BENEFITS OF PESTICIDES
Summary and Conclusions
The production and use of pesticides in the United States is expected
to continue to grow at an annual rate of approximately 15 percent.
Predictions are that insecticides will more than double in use by
1975 and herbicides will increase at an even more accelerated pace.
The foreign use of pesticides will likewise continue to increase with
the organochlorine and organophosphorous insecticides continuing to
represent a significant part of the foreign market.
The use of DDT in domestic pest control programs is rapidly de-
clining with the major need reported to be associated with cotton
production in the Southeastern United States. Although the total
production is declining, an increasing quantity is being purchased by
AID and UNICEF for foreign malaria programs.
Most other persistent pesticides have continued to decline in use
since 1957, a trend that will continue with the remaining uses being
primarily nonagricultural. The shift to nonpersistent pesticides will
continue at an accelerated rate, however, there will be a continued
need for use of persistent materials for the control of selected pest
problems.
Although imaginative and exciting research is in progress, non-
insecticidal control techniques are not likely to have a significant
impact on the use of insecticides in the foreseeable future. There is
evidence of an increased appreciation for the use of integrated con-
trol in the management of pest populations with less persistent and
more selective insecticides playing an important part.
There is a serious lack of information available on pesticide use
patterns, particularly as they relate to nonagricultural uses. Likewise,
available data are usually not obtainable for a proper evaluation of
the economic implications of pesticide use. The United States activity
in international pest control programs is complicated by the magnitude
of involvement and the complexity of diplomatic and agency respon-
sibilities. There are many factors that are influencing the changing
use patterns of pesticides. In addition to new pest infestations, resist-
ance to selected pesticides, alterations in the economics of crop pro-
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duction, and changing agricultural and social patterns, the impact of
public opinion is having a growing influence on the use of pesticides.
The increased concern for new legislation and regulation of the
manufacture, sale, and use of pesticides must not be so structured
as to destroy the incentive for development of new pesticides more
compatible with other desirable environmental qualities.
General History of Pesticides
A pesticide is a, chemical used to cause the death of nonhuman orga-
nisms considered by man to be "pest"; i.e., inimical to human interests.
Rather arbitrarily the following are excluded: pathogenic microor-
ganisms, viruses, bacteria, protozoa generally, endoparasites of man
and other animals, and a host of organisms causing special problems
such as the marine fouling organisms. Technically materials such as
chemotherapeutic agents can be classed as pesticides. However these
are regarded as outside tlie scope of consideration of the commission.
Space does not permit us to trace the history of pesticide usage back
to the dawn of recorded history. For example, it h&s been claimed that
Marco Polo brought pvretlirum to Europe from the far east as a pon-
derous compound of secret origin. Rather, our emphasis will be on the
changes in uses and attitudes toward pesticides which occurred quite
suddenly in the mid-1940's, The insectieidal properties of DDT were
discovered in 1939; it was used in the field, mostly by the military, in
the early 1940's, and became commercially available to the public in this
and other countries about 1945. Similarly1 plant hormones and close an-
alogs were objects of research in the late 1930's, and from these studies
came the herbicide 2,4-D which was released commercially almost
simultaneously with DDT. From that start a liost of new materials
has been produced, a major new industry has come into being, and
agricultural and public health practices have been revised. Education
and research efforts in these areas have not kept pace with develop-
ments in industry, agriculture, and public health. As a result, there
has developed a public fear and public concern over the usage of these
new pesticides. Thus we shall concentrate our attention on this sudden
shift in pesticide practices that developed about 1945.
Pesticides before 1946
Perhaps the earliest pesticides to be used were organic materials of
natural origin. It is not known when pyrethrum was first used to kill
insects nor red squill to kill rats. Preparations of the plant sabadilla
have been used as louse powders by South American natives for cen-
turies. As early as 1763 ground tobacco was recommended in France
to kill a;phids and the active ingredient, nicotine, was discovered in
1809. Plant materials containing rotenone were used as insecticides as
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early as 1848. Petroleum, kerosene, creosote, and turpentine were also
introduced as insecticides in the 18th century. They proved highly
toxic to plants as well as insects but the petroleum oils came into wide
use as larvicides for mosquitoes. Late in the 19th century highly
refined oils with low toxicity to plants were introduced in emulsion
form and gained wide usage. A number of other natural organic
materials were developed as pesticides and are still in use today al-
though their relative importance has diminished.
Inorganic compounds also came into early use as pesticides. The
arsenical, Paris Green, was used against the potato beetle in the Rocky
Mountain region as early as 1865. To combat scale insects in California
lime sulfur washes and fumigation with hydrogen cynanide (not
strictly an inorganic compound) were introduced in 1886. The use of
hydrogen cyanide led to what is one of the earliest recorded instances
of an insect developing resistance to an insecticidal chemical; by 1916 it
was observed that the red scale insect was no longer killed by HCN,
and as this resistance spread geographically the use of this control
gradually declined. Lead arsenate was introduced as an insecticide
against the gypsy moth in Massachusetts in 1892. Sodium arsenite
found use both as an insecticide and a weed killer.
Gradually a number of metal salts, including those of copper, zinc,
chromium, and thallium, came into pesticide use, as well as some
extremely toxic compounds of fluorine and sulfur. Some of the metallic
salts such as cryolite (sodium fluoaluminate) and various salts of
arsenic, lead, mercury, and selenium are extremely persistent in soils
and are removed only by weathering, erosion, or in the bodies of plants
that absorb them from the soil (in the case of mercury some escapes
into the air by volatilization).
The use of synthetic organic pesticides also began before World
War IX. Dinitrophenols found very limited use in Germany as early
as 1892, and such extremely simple compounds as HCN, carbon disul-
fide, and methyl bromide were used very early. Unsuccessful attempts
to synthesize pyrethrum were begun in the 1920's. Naphthalene and
paradichlorobenzene came into use early in the 20th century, and a
few thioeyanates and cyclohexylamines were recognized as potential
insecticides in the 1930's. The insecticidal properties of DDT were
recognized in Switzerland in 1939, and those of benzene hexachloride
(BHC) about 1940 in France and England.
With the advent of World War II our-supplies of pyrethrum for
louse control and red squill for rat control were largely cut oS and
it was imperative to find substitutes for military purposes. DDT then
came into military use and a crash program of screening by the U.S.
Fish and Wildlife Service developed the very poisonous compound
1080 (sodium monofluoroacetate) as a rodenticide. The success of DDT
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in halting a typhus epidemic in Italy in 1943 and 1944 was an un-
precedented achievement which heralded the postwar era of unpar-
alleled benefits in the use of pesticides for human health.
Pesticides after 191$
As DDT came into wide use and its extraordinary insecticidal effects
were recognized there were predictions that all major insect pests
would be eradicated. The dangerous malarial mosquito Anopheles
gambiae had been eradicated in Brazil in the 1930s using pyrethrum
as the principal chemical weapon, and the availability of a low cost
synthetic substitute raised hopes for many more such triumphs. How-
ever, very soon, limitations to DDT use began to be recognized.
The promises of chemical control were viewed with such optimism
that research and agricultural practices often shifted away from tech-
niques such as cultural methods that had formerly been used. Major
efforts were devoted to finding new pesticidal chemicals without the
limitations that had appeared for DDT. It was found that insects
that were resistant to DDT were also often resistant to other related
organochlorine compounds thus the search began for insecticidal com-
pounds with distinctly different chemical structure. Then the organo-
phosphates came into use but resistance often rapidly developed. At
present we are witnessing an expansion in the use of carbamate
insecticides.
Following the appearance of resistance to DDT a tremendous num-
ber of new pesticides has appeared. There are now in the United
States some 900 active pesticidal chemicals formulated into over
60,000 preparations. These include insecticides, fungicides, herbicides
and plant growth regulators. Modern food production programs and
modern public health programs are dependent upon the use of these
pest control agents.
Pesticide Production and Use
The production and use of pesticides in the United States continues
to grow in response to the demands of the U.S. users and the increased
demand for export. Surveys and reports of government and industrial
economists indicate that synthetic organic pesticide production is
increasing at approximately an annual rate of 15 percent with an indi-
cation of more than $3 billion sales by 1975. This is in contrast to in-
creases of approximately 37 percent for the 5-year period, 1963 to 1967.
The total dollar value of all pesticides produced in this country was
$440 million in 1964; this has increased to $12 billion in 1969. Herbi-
cide sales, as indicated by U.S. Department of Agriculture surveys,
have risen 271 percent since 1963 which represents more than double
the rate of increase for all pesticides. Predictions are that insecticides
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will more than double in use by 1975 to more than $600 million, while
herbicide uses will increase to more than double that of insecticides
($11^ billion) during that same period. The value for all herbicides
produced increased from $200 million to $800 million in a 5-year
period from 1964 to 1969 and is expected to reach $1,350 million by
1974.
Foreign uses for pesticides lias continued to expand as indicated by
U.S. exports, as well as by surveys of European agricultural chemicals.
U.S. exports in 1967 were approximately $196 million. Insecticides
were responsible for approximately 60 percent of the international
movement. Approximately 45 percent of these exports were repre-
sented by the organophosphorous and organochlorine insecticides
which were about equally divided. In 1967, there was a reduction in
DDT exports and an increase in other organochlorine and organophos-
phorous materials. Sizeable quantities of pesticides continued to be
shipped from the United States to eastern European countries in 1967,
with the largest share going to the Soviet Union.
The United States produces from 50 to 75 percent of all pesticides
manufactured in the world. However, it is predicted that the percent-
age of the U.S. contribution is likely to be reduced as other countries
develop capacities or increase existing capacities to make these chemi-
cals. It is likewise predicted that insecticides and fungicides will
continue to dominate the international market for some considerable
period of time.
Insecticides
Although the rate of growth for insecticides is not as spectacular
as that for herbicides, manufacturers' sales of synthetic organic insec-
ticides in 1967 reached 301 million, which was 10 percent above the
previous year and represented 38 percent of the total share of the
pesticide sales. In 1967 the United States exported $150 million worth
of insecticides which was an increase of about 14 percent over the
previous year. These increases resulted largely from exports of tech-
nical organochlorine and organophosphate technical materials.
A 1964 survey by the U.S. Department of Agriculture indicated
that U.S. farmers used approximately 2 million pounds each of 12
different insecticides, which accounted for 85 percent of the total vol-
ume. Toxaphene was used in largest volume, followed closely by DDT;
these two made up 46 percent of total pesticides used in 1964, The same
survey indicates that farmers applied two-thirds of the total quantity
of all insecticides used 011 farms on three crops: Cotton, corn, and
apples. The cotton market accounted for more than half of the total
including about 80 percent of the methyl parathion, 86 percent of the
endrin, 70 percent of the DDT, and 69 percent of the toxaphene. The
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371-074 O—' 5
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corn market accounted for 10 percent of the total, including 96 percent
of the aldrin and 84 percent of the heptacblor, Latest data made
available by the USDA Economic Research Service from their 1966
pesticide-use survey indicates that farm use of pestieides in 1066 (in
terms of active ingredients) was up about 10 percent over 1964. Over-
all, insecticide and fungicides use (exclusive of sulfur) remained about
the same as in 1964 even though the use of insecticides on cotton was
down because of the large reduction in acreage. However, herbicide
use was up more than 33 percent. Leading products among the insecti-
cides continue to be toxaphene, DDT, and aldrin, accounting for over
half of ail insecticides used by farmers in 1066. Shifts in ingredient
usage among insecticides from 1964 to 1966 showed a slight decrease
in the use of chlorinated hydrocarbons and an increase in the use of
organophosphorous compounds. The latest production figures (1967)
indicate that the organochlorines continue to make up approximately
one-half of the U.S. production and of these approximately 50 percent
is DDT.
Persistent insecticide use patterns
DDT.—U.S. DDT production during 1967 was 103 million pounds,
down approximately 27 percent from 1966. Exports during 1967 were
82 million pounds, down approximately 10 percent. Over half of all
DDT exports were in the form of 75 percent wettable powder used
primarily for mosquito control. In 1967 five countries: India, Thai-
land, Brazil, Nepal, and Mexico, received over two-thirds of the export
tonnage of this formulation. Economic Research Service surveys indi-
cate that the U.S. output of DDT is approximately 40 percent less
than the peaks reached in 1960 to 1963, Exports are claiming an
increased share, approximately 70 percent of this production. Domes-
tic uses were reduced nearly 50 percent between 1958 and 1966, DDT
has been replaced by less persistent pesticides in many States. Of
special significance has been the reduction in its use for large-scale
forest insect control programs, mosquito larvicide and in some
instances, mosquito adulticide programs, as well as many agricultural
uses. The use of DDT on agricultural crops ranges from the more than
200 entries in the Federal recommendations to emergency uses only
in certain States.
Large amounts of DDT are used in this country for the production
of food and fiber, for control of mosquitoes and bats and for other
limited purposes. Substitute products are usually more expensive
and sometimes less effective. Many of the substitutes have acute tox-
icities representing greater degrees of hazards to the user than DDT.
Other substitutes have a lower mammalian toxicity, but present a
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much greater hazard to pollinating insects. Still others are more toxic
to fish and wildlife.
It is not possible to summarize the advantages and disadvantages
of substitute chemicals that are presently available since there are
no general substitutes. Several available partial substitutes have a
variety of disadvantages including increased mammalian toxicity,
lack of tolerances on food commodities, decrease in insecticidal value,
high cost, increased toxicity to bees and pollinating insects, and
increased toxicity to fish and wildlife. The biological impact of large-
scale use of many substitute chemicals is as yet unknown.
The usefulness of noninsecticidal control techniques has been demon-
strated on a laboratory scale for several of the major economic insects.
The utilization of the sterile male technique and attractants plus
pesticides have been used for the control of the screw worm in cattle
and of certain fruit flies, both in the United States and on certain
Pacific Islands.
Although the total production of I)I)T is declining, an increasing
quantity of this compound is being purchased by AID and TJNICEF
for foreign malaria programs. It is estimated that more than half
of the total U.S. production of DDT is exported by AID and UN IC E F
for malaria eradication. It is evident from the production data that
the use of DDT in domestic pest control programs is declining and
this appears likely to continue.
It is reported by well informed scientists that as far as insect vectors
of disease are concerned there are none known which are normally
susceptible to DDT that cannot be controlled with a substitute. How-
ever, stopping the production of DDT in this country would be a very
serious blow to foreign malaria eradication programs, now being
supported largely by AID. These are normally under the actual super-
vision of WHO teams. AID records over the past several years indi-
cate shipments of DDT have varied but the trends are slightly
downward. The consensus of AID personnel is that an abrupt with-
drawal of other organochlorine compounds would create immediate
and critical problems for growers throughout much of the developing
world, and could have a deleterious effect on world food production
and protection of public health. A gradual withdrawal, alow enough
to permit substitution and demonstration of organophosphate, carba-
mate, and other chemicals, would minimize the impact of such action.
Such a change would require a vast educational program. Reports
from authorities interviewed indicated that it was likely that malaria
programs would gradually be discontinued if they were forced to use
substitutes for DDT.
The persistence of DDT is the essential characteristic that makes it
effective as a malarial eradication frool. A malarial victim may re-
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main infective for many months to mosquitoes that feed upon him. To
interrupt malaria transmission, constant protection against bites from
infected vectors must be provided for several years. The maintenance
of an insecticidal residue on interior surfaces of homes provides this
type of protection. The magnitude of the areas to be covered and the
inaccessibility of remote rural areas in underdeveloping countries
makes frequent spraying of houses impractical and expensive. "With
DDT one or two treatments annually are usually sufficient. The appli-
cation of DDT to the interior surface of houses results in a minimum
contamination of the outdoor environment. A recent WHO release
summarizes the status as follows: "In considering the pesticide prob-
lem, we must not forget the enormous benefits insecticides have brought
to humanity. DDT has been instrumental in controlling some of the
most important vector-borne diseases of man. The concept of malaria
eradication rests completely on its continued use. The record of safety
of DDT to man has been outstanding during the past 20 years and its
low cost makes it irreplaceable in public health at the present time.
Limitations on its use would give rise to greater problems in the ma-
jority of the developing countries."
It has also been suggested that banning the use of DDT in this coun-
try and at the same time sending it overseas for malaria programs
would be looked on with disfavor by recipient countries.
Recent reports by the World Health Organization indicate that the
control of many of the most important vectors of human diseases is
still entirely dependent on insecticides and no effective or economically
feasible alternatives are available. There luis been some reduction in
the use of DDT in vector control programs partly as the result of
progress in malaria eradication and partly due to the development of
insect resistance. It is very difficult, if not impossible, to obtain an
accurate figure on the amount of Federal money spent on the chemical
control of vectors domestically or in foreign countries. In the past
10 years it is well over a half-billion dollars. AID and its predecessors
have spent at least this much on foreign malaria programs since they
were initiated in the early 1950's. If the crisis with respect to the use
of pesticide chemicals for vector control is to be overcome, a large
increase in funds for research is mandatory. A substantial investment
will be necessary to provide a solution to the problems involved in
controlling insect vectors without the use of presently available chemi-
cals. Although DDT is still involved in some of the international food
production programs sponsored by U.S. agencies, there is a feeling
that a withdrawal or systematic reduction of DDT would have a
minimum effect.
There is a principle of international diplomacy which recognizes
that a free and independent nation has a right to make its own choice
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without dictation by any other power. For example, pesticides shipped
to a foreign purchaser on his own specifications are exempt from the
requirements of the Federal Insecticide, Fungicide, and Rodenticide
Act of 1947, as amended. Accordingly, information on pesticide usage
must be volunteered by the foreign user or his government rather than
demanded by AID as a basis for authorizing loans under which pesti-
cides are to be purchased. All pesticide purchase requests handled
under AID or comparable funds should be funneled through an
appropriate scientific staff, A followup of the use patterns and effec-
tiveness of the material shipped should be an important prerequisite
to any fund release or shipment. Such reports should include a sum-
mary of efficacy, reports of accidents to humans or other animals, as
well as any adverse effects on wildlife. Such input will require a new
philosophy as well as substantial reorganization and increased support
for proper handling of future pesticide shipments to foreign countries.
Methoaychlor.—In comparison with DDT, methoxychlor produc-
tion and usage are at much lower levels. Use levels have been quite
stable over the past 15 to 20 years, although its pattern of use has
varied and changed somewhat over this period.
Currently, about 75 percent of the methoxychlor sold is used for
fly control on cattle and in farm buildings, with the remainder divided
between crops, control of elmbark beetles (Dutch Elm disease), grain
bin treatment, home garden and household insecticides. The largest
recent shift has been in crop use; from primarily fruits and vegetables
in earlier years, to forage crops particularly alfalfa weevil control.
Restriction in use of the "persistent" insecticides should have only
minor effects on use of methoxychlor: (1) Methoxychlor is not very
effective against a number of the pests controlled by these com-
pounds—for example, soil insects such as corn rootworm, wireworms,
etc., (2) Other compounds (such as various organophosphates or
carbamate insecticides) are available and registered for many uses,
and would probably be used more extensively, if the persistent insecti-
cides were banned.
A moderate increase (5-10 percent) in methoxychlor usage is pro-
jected in the uses for which methoxychlor already is accepted (cattle,
farm buildings, etc.) plus possible increases for area control of mos-
quitoes, blackflies, etc.
Aldrin.—This compound has been an effective and extensively used
soil insecticide. Roughly one-half of the U.S. corn acreage treated
with soil insecticide last year was treated with aldrin. Particular
insects of economic importance that were controlled are ants, cut-
worms, wireworms, flea beetles, Japanese beetle grubs, seed corn
beetles, seed corn maggots, European chafer grubs, white grubs, corn
bill bugs, sugarcane beetles, webworms, white fringe beetle grubs,
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crickets, and corn rootworm larvae. In areas of rootworm resistance
to organochlorines narrow spectrum materials are used at rates suffi-
cient to control rootworm. The highest sales for aldrin were in 1966.
In 1968 sales of aldrin had dropped 30 percent and by 1972 the
estimates indicate a reduction of 60 percent from the highest sales
year.
Dieldrin.—This compound is used widely to control a variety of
pests, especially when a long lasting residual effect is desired. These
residual uses for dieldrin include its application for termite control,
insect control on lawns, turfs, ornamentals and flowers, and at the
present time household residual sprays and permanent moth proofing
of fabrics. The bulk of the material is used for termite control. In
1968, 81 percent of the aldrin and dieldrin agricultural use was for
corn soil insects. Other agricultural uses made up 11 percent and non-
agricultural specialty uses including termite control. Government
programs and so forth, an additional 8 percent.
The highest sales year for dieldrin was in 1956. Usage has steadily
decreased because of resistance in the cotton boll weevil and certain
other agricultural pests. This is a 70-percent drop in a 12-year period.
Estimates indicate that usage will drop another 10 percent by 1972,
practically all remaining uses being for nonagricultural purposes.
Endrin.—The major domestic use for endrin is as a cotton insecti-
cide. The projected use of endrin for this purpose indicates a decrease
between 1969 and 1973 as a result of increased insect resistance.
Projected use in international areas for endrin indicated a relatively
stable use pattern or possibly a slight decrease. All uses of endrin
in the United States are on a no-residue basis. Substitute insecticides
for endrin are being evaluated in many developing countries. How-
ever, economic factors have limited the introduction of substitute
materials; for example in India, studies indicate that substitute insec-
ticides for control of rice and cotton insects would increase the cost
of treatment 80 to 95 percent.
Heptachlor.—This compound is primarily a soil insecticide. It is
anticipated that the heptachlor used in the United States will be
primarily for control of the soil insect complex in corn, which will
represent between 55 and 75 percent of the domestic use. The second
most significant use of heptachlor is in the commercial pest control
field. At present this usage for primarily structural termite control
represents about 15 percent of the use pattern and is expected to in-
crease to some 34 percent by 1973. In 1960 there was a 50-percent de-
crease in the use of heptachlor over 1959. This was in response to the
Food and Drug Administration's concern for the residues of its
metabolite heptachlor epoxide. An important use for heptachlor in
early years was the control of alfalfa weevil. A significant reduction
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in the use of heptachlor occurred between 1963 and 1964 as a result of
the residues reported in milk and subsequent removal of heptachlor
for this use.
Chlordane.—The agricultural usage of chlordane is primarily as a
soil insecticide. It has been especially important in the home, lawn, and
garden pest control market. These markets represent its major use,
which is estimated at about 70 percent of the total use between the
years 1969 through 1973. Approximately 50 percent is estimated to
be used in the pest control market for primarily structural termite
protection and about 10 percent in the home, lawn and garden use,
primarily for turf treatment. About SO percent is estimated for agri-
cultural usage.
Structural pest control is expected to continue its current rate
of expansion of about 10 percent per year. The same expansion can be
expected in the industry pesticide purchases, which are now about
$40 million per year at the wholesale level. Further use of persistent
pesticides in the pest control industry is likely to be influenced by
development of resistance in important pests. In the mid-1950's,
diazinon replaced chlordane as the dominant insecticide in general pest
control, because of resistance. Diazinon resistance has not been a major
problem. A carbamate insecticide, such as Baygon, might rise in im-
portance if substantial resistance to diazinon should materialize.
Resistance in termites appears to be unlikely as a factor affecting
choice of insecticides in the foreseeable future.
The commercial structural pest control industry indicates that it
has approximately 18,000 men rendering periodic service. Each tech-
nician may treat 10 to 20 premises a day and use a persistent insecticide
in almost every one. The principal pests controlled are cockroaches,
ants, fleas, ticks and pests of fabric, stored food, and wood products.
Practical control requires an insecticidal residue to be available at
such time as the pests emerge from concealment, from pupation, or
from the egg. Aldrin, chlordane, dieldrin, and heptachlor are the
materials primarily used for subterranean termite control. An example
of the magnitude of this problem is provided by figures available from
the State of Georgia where 46 thousand termite jobs are performed
each year. Massachusetts reports nearly a thousand inquiries per year
by the public regarding termite control. It has been calculated that
three out of five houses in the Midwest can be expected to become
infested with termites. This applies to the Detroit, Louisville, Kansas
City and Milwaukee areas and assumes a house to have a life expectancy
of 35 years. The USDA calculations indicate that the annual cost
to U.S. homeowners is approximately half a billion dollars from
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termite damage. The persistent pesticides indicated above provide
18 to 20 years protection in most instances.
Noninsecticidal control techniques are not likely to have any sig-
nificant impact on future use of pesticides in household and structural
pest control.
The commercial pest control operator is using a small and decreasing
amount of DDT. These uses are often involved with the control of
bats in structures, house mice where control is not possible with
other acceptable materials, and limited uses for ants, cockroaches,
garbage pests, scavengers, and ectoparasites.
A large portion of the pesticides used by the Department of Defense
is shipped overseas. More goes to Vietnam than to any other country.
Relatively little persistent insecticide is used for area control of insects.
The Department of Defense does little mosquito-larvae control and
malathion or naled are the insecticides most frequently used for adult
mosquito control. Mirex is used for fire-ant control on some of the
installations in the southern U.S. and 10 percent dieldrin is used on
small areas when recommended by the U.S. Department of Agriculture
Plant Pest Control Division. Persistent insecticides are used for ter-
mite control, some for residual spraying in warehouses and other
quarters and for selected inseets. The Department of Defense has
pest control operations on military properties in the United States
and overseas. The Armed Forces Pest Control Board provides co-
ordination and each service conducts programs tailored to resolving
a specific problem. None of the Department of Defense budget is
commonly allocated for pesticide regulation, and no employees are
occupied full time on this matter. The importance of such regulation
is recognized and many measures are taken to insure that pesticides
are utilized properly. In 1969 $li/£ million was allocated for pesticide
research by the Department of Defense. The majority of the money
was used to support research conducted under contract or grant with
only six Department of Defense professional personnel devoting more
than 50 percent of their time to pesticide research.
The Department of Defense conducts pest-control programs as re-
quired on the 30 million acres of property that it controls in the United
States. These programs are regarded as essential for the protection of
the buildings and perishable stored products that are required for the
Armed Forces. The protection of forest and recreation areas is also of
major importance. Pest control to protect the health and welfare of
citizens residing on and adjacent to military installations is also im-
portant. While price data are not readily available, current costs of
the Department of Defense Pest Control Program in the United States
is approximately $7.7 million per year.
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The organochlorines are used extensively on several of the quaran-
tine programs. These materials are considered to be the most practical
and in some cases the only means of treating products as well as
processing of cargo areas to prevent the spread of several important
insect pests. The organochlorines are the backbone of the present
regulatory program for whitef ringed beetle, Japanese beetle, Euro-
pean chafer, fire ant, and sweet potato weevil. These scientists responsi-
ble for regulatory decisions have indicated that there is no satisfactory
substitute for these chemicals to meet the requirements for regulation
under provisions of the quarantine laws. There is also the joint agree-
ment with the committee concerning the enforcement of similar quar-
antine regulations on four domestically quarantined pests—namely,
European chafer, Japanese beetle, cereal leaf beetle, and gypsy moth.
The Republic of Mexico is also concerned about certain of the U.S.
domestic quarantine pests, but it accepts our regulatory programs and
certification thereunder for movement in Mexico as it relates to these
pests. Some organochlorines are also employed as a basis for allowing
movement into the United States of certain products of foreign origin.
The principal commodities involved in these regulatory programs are
nursery stock, sod, bulbs, corms, and plant crowns, stone and quarry
products, industrial supplies, timber products, sweet potatoes, Irish
potatoes and transplants. Additional regulatory responsibilities are
included with the treatment of areas around processing plants, truck
and rail transportation centers, trailer camps, campgrounds, and
airports.
Summary of foreign insecticides uses
In general, there is limited information available on the economic
impact of pest infestations on foreign agriculture and related pesti-
cide use patterns. However, the summary provided the Commission
by Shell Chemical Co. scientists gives an updated appraisal of the
international uses of persistent pesticides and is included as appendix
A of this report.
Specific data are not available from most foreign countries on past
use; however, the Indian report published in 1967 by the Special
Committee on Harmful Effects of Pesticides has provided, interesting
and relevant statistics regarding the use and projected use of insecti-
cides. In India the use of pesticides has increased from the treatment
of 10,120 hectares in 1946-47 to about 6.15 million hectares in 1961-62
and has risen to 17.4 million hectares in 1965-66. This latter figure
represents about 11.2 percent of the total crop area. The amount of
DDT used in plant protection is expected to quadruple from 600 metric
tons in 1964-65 to 2,400 metric tons in 1968-69. The amount of aldrin,
dieldrin, lieptachlor, and chlordane is expected to increase from about
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90 metric tons in 1964-65 to 1,050 metric- tons in 1968-69, a factor of
12. The report indicates that these increases in the use of organo-
chlorine insecticides are not likely to result in any increased hazard
to human, beings and domestic animals, but that they may have a sig-
nificant effect on wildlife. The increase in the use of DDT in plant
protection will be accompanied by a planned decrease in its use in
public health from 8,426 tons of technical material in 1964-65 to 3,456
metric tons in 1968-69. In 1967, approximately 20,326 metric tons of
pesticides, technical grade, were being used, of which 16,262 metric
tons were manufactured in India and the remaining imported. Pre-
dictions were for the requirement of 77,509 metric tons of technical
material for use in 1968-69. Within the period of 1965-66 to 1968-69,
it is predicted that the area to be treated with pesticide will increase
more than 5% times and will cover 85 million hectares (54 percent of
the total crop area).
Pesticide economics
Prior to 1945 it was common to find statements in the literature
estimating the loss to pests of crops and stored commodities in the
United States at "10 percent," or "at least 10 percent." One standard
textbook of economic entomology (Metcalf and Flint, 1939) attempted
to be more thorough and to estimate for individual crops and com-
modities the loss from insect pests as of 1936 both in percentage of
the crops destroyed and in dollar values. The latest revised edition
of that textbook gives a revised estimate based on 1957 data showing
percentage losses to insects of various crops and stored products which
are virtually identical to the 1936 figures. The dollar values of the
losses, however, have approximately doubled in most cases, in part
reflecting increased prices. In the appendix we have added a final
column giving the percentage of the potential crop production lost
to insects outside North America.
The economics of pest control is made up of the interrelationships
of the benefits, costs, and side effects. That is, the incremental benefits
of another unit of control must be equal to or greater than the asso-
ciated incremental costs. This is not an easy task because in pest con-
trol there are many different kinds of pests. Each may be associated
with many different damages and there are numerous ways to control
each pest. At present, research in this important area has been pri-
marily involved with an attempt to measure in aggregate the effects
on farm sales associated with varying levels of pesticide use. The
only source of data for this work has been the secondary data from
the agricultural census and other data variables from the USDA,
such as the pesticide use surveys of 1964 and 1966.
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The funds allocated to the Economic Research Service by the Agri-
cultural Appropriations Act of 1965 ($500,000) provided for research
on the cost and benefits of alternative methods of controlling' plant
and animal pests, and the collection of basic data on current uses of
pesticides and costs and methods of controlling pests. This research
was divided into three phases: (a) Biennial surveys of a nationwide
sample of farms to obtain data on practices farmers employ to control
pests by the use of chemicals, and the costs of these practices; (5)
analysis of selected alternative methods of pest control with emphasis
on comparative costs and returns in selected areas; and (c) analysis of
the economic implications of alternative methods of pest control both
on the farm and for agriculture as a whole.
The economic analysis of the benefits of pesticides is largely an
undeveloped area. A full cost-benefit appraisal of pesticides in the
American economy or in agriculture has not been made. Gaps in pres-
ent knowledge of the technical relationship of pesticides in the fields of
agriculture, health, and natural resources make such an evaluation
difficult.
Available data are not adequate to properly evaluate the economic
implications of pesticide use. Estimates of the total volume of pro-
duction of these chemicals are reasonably accurate, but only aggregate
estimates are available to indicate the extent that chemicals are used
in agricultural production. Little information is available to indicate
the use of the many chemicals in the production of specific crop and
livestock commodities. Costs of side effects have not been evaluated
for inclusion in the analyses.
Headley, who has pioneered in this area, is quick to point out that
there is not a large body of time series data available and, therefore,
cross-section studies have been used. These estimates are inadequate in
several respects. They are not generated experimentally and they may
be measures only of association and not measures of the contribution
of pest control with other things constant. In addition, the cross-sec-
tional analysis measures change in farm sales at the prices determined
for the year of the cross-section measurement, based on supply and
demand in that year, Headley's early results show an incremental con-
tribution of about $4 to $5 per $1 of pesticide expended by a farmer.
A later study shows contributions per ounce of technical material by
production region. The impact of chemical pesticides is strongest over-
all in the area south of the Ohio River and west of the Mississippi. The
Pacific region, South Plains, and Northeast also devote more produc-
tion resources to chemical pesticides than does the Corn Belt, North
Plains and the mountain regions. Headley points out that part of these
differences is due to resource values such as land and labor, but it
seems reasonable that they also reflect pest problems, such as biological
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conditions for pests and the product orientation of agriculture region-
ally such as cotton, vegetables, tobacco, and fruit, as compared with
cereals. Sufficient experimental data are not available nor do they seem
to be in the process of development. The general needs appear to be:
1. Functions that relate pest infestation to crops or livestock yields
both quantitative and qualitative, and that are representative for prod-
ucts produced, pest infestations, and regions.
2. Functional relationships that relate pest control by the various
methods, compounds, cultural pratices, biological control methods, to
pest infestation, not only for average seasons but over time, to indicate
population trends, target pest species, and also associated pest species.
3. Information that relates a level of use of a pest control method
to the known side effects in order to ascertain changes in side effects
resulting from different levels of pest control methods. From this
kind of information estimates of the damage prevented as a result
of the changes in control could be developed for products by regional
products by pest. In addition, estimates of pest population changes
due to the control change could be generated and, finally, changes in
side effects as a function of changes in control could be estimated and
related to yield damages prevented.
Factors Influencing Changing Use Patterns
New pest problems that can have an effect on pesticide usage come
about through several means. Many pest problems develop from new
introductions either coming into the United States or from one area
to another within the country. The introduction of such insect pests as
the gypsy moth, and more recently the cereal leaf bettle, have had a sig-
nificant effect on the use patterns of insecticides. When new pest
problems are recognized, efforts are often initiated to restrict their
migration usually through quarantines, and attempts are then made to
eradicate the pest. Widespread control measures may become neces-
sary when the new species become widely distributed.
Pests can develop a change in the preferred host plant and thus
alter their economic significance. New problems which affect pesticide
usage are created when previously undeveloped areas are utilized for
public recreation. Such pest problems as disease-bearing mosquitoes
and ticks and noxious weeds such as poison ivy and ragweed are typical
of such situations.
When a new agricultural crop is produced more intensively new
pest problems will often occur. Other occasions arise where an insect
becomes a pest because factors such as temperature, moisture, food
supplies, etc., are optimum to bring about a high population density.
Examples of this are the various species of grasshoppers which in
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certain years build up to tremendous numbers and in other years may
not be a problem.
Pest resistance.—The term "resistance" is applied to formerly sus-
ceptible species whose populations can no longer be controlled by a
given pesticide at the rates normally recommended. The earliest in-
stance of resistance in the United States was noted in 1908 when the
San Jose scale resisted lime sulfur sprays in a few orchards in Wash-
ington. Early resistance to DDT was seen in the housefly by 1946 in
Sweden. Fortunately, acquired resistance to DDT apparently does
not involve a cross-resistance to cyclodiene derivatives, nor to organic
phosphate compounds, and vice versa.
Resistance is a character developed by selection within a population
of a species normally susceptible to n particular pesticide. It is an
inheritable characteristic, developing only in populations that already
have the factors for resistance, and not inducible by habitation during
the lifetime of the pest organism.
Some 224 species of insects and acarines in various parts of the
world have developed resistance to one or more groups of insecticides;
of these, 127 are agricultural pests and 97 are pests of medical and
veterinary importance. Resistance can be discussed in three major
categories; DDT, cyclodiene, and organophosphate resistance. Of these
three, DDT resistance occurs in 89 species, cyclodiene resistance in
116 species, and organophosphate resistance in 39 species. There are
many populations in which two or three of the resistance factors are
present simultaneously.
Since resistance is the result of Darwinian selection, it should be
expected to develop wherever insects are exposed for long periods to
selecting levels of the insecticide that causes some degree of mortality
short of 100 percent. The change toward resistance will be more abrupt
when the selecting level, in terms of percent mortality, is higher, and
there will be less delay in its development when the area treated is
wider and the surrounding untreated population is smaller. Residual
insecticides are ideal selecting agents because they persist such a long
period at selecting levels of contamination. The practical outcome of
resistance to chlorinated hydrocarbon compounds has been the intro-
duction of a variety of new organophosphate and carbamate
compounds.
A'ew pesticides.—To meet the residue problems associated with many
uses of persistent pesticides, a wide range of organophosphate and
carbamate insecticides has been developed. For example, malathion,
carbaryl, and related materials are now used for the control of many
insects where it is essential that crops or livestock are not treated with
persistent materials. Ciodrin and dichlorvos are now available for the
control of flies in dairy barns and milking areas, and for direct use
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on livestock. For gypsy moth control, DDT is being replaced in many
iireas by Sevin (carbaryl). Abate, a compound with selectivity for
mosquito larvae, is replacing DDT in many areas.
New soil insecticides have replaced aldrin and dieldrin for certain
agricultural insect control programs. Many newer organic phosphate
compounds, such as phorate and disulfoton are applied as plant sys-
temic insecticides in the form of granules.
New methods of application.—New application methods are being
used to decrease the pesticide contamination hazards and to increase
pesticide efficacy. Improved forecasting of outbreaks of pest infesta-
tions has often resulted in a reduction in the number of pesticide appli-
cations necessary for adequate control.
Direct incorporation of pesticides into soil has resulted in a reduc-
tion of such hazards as spray drift and residue on standing foliage. By
direct furrow soil application, a smaller amount of pesticide can be
used and still provide effective control.
The current interests in the use of chemical abtractants and chemo
sterilants involve using baits which, in some instances, can control
the insect pest without contaminating the environment. The chem-
osterilants and the poisons used with the attract ante are moderately
toxic to mammals but there are newer ones on the way that are expected
to be much safer.
Alternate control techniques.—Mechanical and cultural control
measures are associated with normal agricultural procedures and gen-
erally involve certain changes in normal farming techniques rather
than the addition of special procedures. Although widely used in the
past, many cultural control techniques have been replaced by labor-
saving chemicals.
Rotation of crops is often an efficient way to reduce weeds and
insects. Another cultural practice that has been very effective is the
development of insect and/or disease-resistant plant varieties. In gen-
eral, breeding for pest resistant varieties is extremely slow and tedious
and must be directed at a single type of pest. To be effective, resistance
to a given disease or insect must be combined with desirable agronomic
or horticultural characteristics.
The successful use of biological control techniques has been respon-
sible for the control of a limited number of pest species. Most success-
ful cases to date have involved the use of parasitic or predaceous
insects. There are at least 18 such successful examples in the United
States where noxious insects have been controlled by other insects.
Microbial control of certain insect pests has received increased
attention in recent years. Nematodes, protozoans, bacteria, fungi, and
viruses have been tested experimentally.
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Availability of materials to work with is the limiting factor in
using pathogens in control programs. There are also problems of
registration of labels and quality control assays which need to be
worked out for each organism.
The potential use of chemosterilants on a wide scale to control insect
populations is an intriguing one. The development of suitable com-
pounds, acceptable application methods, and a better understanding
of insect habits nre areas of research which must be fully explored
before any serious effort can be made to use chemosterilants on a wide-
spread commercial basis. It is likely that through continued research by
universities, government agencies, and the chemical industry, relatively
safe and specific chemosterilants will be developed for field use.
The potential uses of pheromones and other insect attractants fall
into two categories: (1) population density surveys and (2) direct
behavioral control. Although early work has been promising under
controlled conditions, there are many questions yet to be answered
before pheromones will have a major role in insect control.
Availability of Labor.—The availability of labor in agriculture
today is forcing a tremendous push toward completely mechanized
farming. It is a well-known fact that the trend is toward bigger and
fewer farms, and it is becoming more and more uneconomical to employ
hand labor to care for and harvest crops. As a result, there is a greater
reliance on pesticides.
Economic Pressures.—Economic pressures are put on the grower
from a number of sources.
The public demands top quality produce and the grower must meet
these demands to obtain the premium market price. This requires pro-
tection of the produce from planting through harvest and until it
reaches the consumer.
Certain regulatory pressures concerning contamination of processed
foods with pest fragments have a strong influence on pesticide usage
in order to reduce or eliminate the pests.
Pesticide Groups and General Uses
INSECTICIDES AND MITTCIDES
Insecticides may be classified in several different ways. One system
that has been widely used is based on the mode of entry of the insecti-
cidal agent into the insect—stomach, contact, and fumigant poisons.
Stomach poisons are materials which are ingested by the insect and kill
primarily by action on or absorption from the digestive system. Their
effectiveness is generally limited to the control of chewing insects. Con-
tact poisons are absorbed through the body wall and must come into
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direct contact with the insect to kill. They are usually required against
sucking insects. Fumigants enter the tracheal or respiratory system in
the form of a gas and are effective against insects found within an
enclosure.
Because of the large degree of overlap found when using this system
of classification, insecticides are more frequently discussed in terms
of their chemical nature. The major divisions are inorganic and
organic. Organic insecticides are further broken down into oils, botani-
cals, and synthetic compounds. The synthetic compounds are by far
the most widely used and are further subdivided on the basis of their
chemistry.
1. Inorganic Insecticides.—Although inorganic insecticides have
largely been replaced by more efficient organic compounds, some still
find a place in agricultural pest control. Lead arsenate is used primarily
on trees and shrubs to control chewing insects. It may also be used in
baits for the control of ants and cockroaches. Other inorganic insecti-
cides occasionally used are: calcium arsenate, various sulfur deriva-
tives, and Paris green. Their general use is restricted because of toxicity
to man, persistence, and the advent of newer and better insecticides.
Oils.—These are used in an emulsion and are employed as insecti-
cides in a number of ways. They may be used as solvents or carriers for
insecticides, such as diesel fuel in aerial applications. Oils also serve to
carry insecticides over water for mosquito control or even oil alone may
be used for this purpose. Highly refined oils, which are relatively non-
phytotoxic, are applied to tree foliage. These are known as summer
oils and are effective in controlling aphids, mites, and scale insects on
fruit trees. The dormant oils, which are less refined, are restricted in
use to application when no foliage is present. They are effective in
eliminating over-wintering eggs of mites and aphids, and in control-
ling scale insects.
3. Botanicals.—A number of plant extracts are in active demand as
insecticides despite the variety of synthetic organic compounds now
available. These extracts, or botanicals, break down into harmless
compounds soon after application and with a few exceptions may be
handled with relative safety. They are quite specific in their effective-
ness, being limited largely to soft-bodied insects such as aphids, thrips,
and certain caterpillars, particularly the younger stages. The more
important toxicants include pyrethrins, rotenone, and a few related
compounds. All are of complex structure, and there has been little
success in their development by synthesis, with the notable exception
of allethrin, which is a synthetic "pyrethrin."
Pyrethrin and allethrin are formulated as dusts, sprays, and aero-
sols, usually with a synergist to increase insect toxicity. They are noted
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for rapid knockdown of insects through action as a nerve poison. Their
low mammalian toxicity makes them very suitable for use around live-
stock and as household sprays. Rotenone is a selective insecticide that
kills by inhibiting oxygen utilization by the insect. It may be used
with relative safety around most animals, although swine are highly
susceptible to its toxic action. Its greatest use as an insecticide has
been for control of cattle grubs and external pests of livestock. Other
botanicals of lesser importance include sabadilla, ryania, barthrin,
dimethrin, and nicotine.
4- Synthetic Organic Insecticides and Miticides.—The synthetic
organics dominate the insecticide field today. Rapid developments
makes an up-to-date classification difficult, but they can be broadly
grouped into general chemical classes.
a. The organochlorines or chlorinated hydrocarbons have been
widely used since 1945. The outstanding feature of this group is the
prolonged residual effect by both contact and stomach action. They
are essentially insoluable in water, and have little or no tendency to
be absorbed systemically into the plant. They have shown effective
persistence for over 10 years in tests where massive soil treatments
were used as in termite control. Contrary to popular belief, the or-
ganochlorines are rather specific in their action, being highly poison-
ous to insects in certain groups, and comparatively ineffective in
killing others.
Resistance to these insecticides has developed in a growing number
of pests during their period of use. The development of resistance
to one organochlorine is usually followed by resistance to others.
Hazards to applicators are minimal when these insecticides are used
according to directions with the exception of endrin which must be
handled with extreme care.
The problem of illegal residues persisting after harvest usually
comes from this group of insecticides.
The most widely used organochlorine, as well as the most publicized,
is DDT, which belongs to a class of Compounds known as diphenyl
aliphatic chlorinated hydrocarbons. Other compounds related to DDT
are: Rothane (TDE), Marlate (methoxychlor), Kelthane (dicofol),
Acaraben (chlorobenzilate), Acaralate (chloropropylate), as well as
a few more of lesser importance, including Dimite, Karathane (dino-
cap), Bandane, and Dizane. These compounds are used at rates of
1 to 2 lb/A as insecticides and 2 to 4 l'b/A as miticides.
A second class consists of chlorinated aryl hydrocarbons. This group
contains a number of widely used compounds again mostly in agri-
culture. Examples are benzene hexachloride, chlordane, heptachlor,
aldrin, dieldrin, endrin, endosulfan, toxaphene, and several more
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of lesser importance. Of these compounds, chlordane, aldrin, and
dieldrin are widely used in structural pest control; e.g., termites.
b. Organophosphorous insecticides.—Organic phosphates have a
wide range of insecticidal effectiveness. They are mainly contact insec-
ticides, although many have fumigant action.
The organic phosphates act as inhibitors of the enzyme, cholinester-
ase. Often the effect is not immediately obvious and a worker may be
exposed to the poison on successive days without apparent ill effects.
However, grave symptoms appear when the critical level of enzyme
inhibition is reached. The hazards of using the phosphates vary
widely, depending on the compound, but they are generally considered
to be more toxic than many of the organochlorines.
The phosphates as a whole do not have a long residual action. This
makes some undesirable where a long period of protection is needed,
but many of the phosphates are most important where residue toler-
ances limit the choice of available insecticides, and in control of insects
resistant to chlorinated hydrocarbons.
Agriculture provides the major market area for the organic phos-
phates although a few are of importance in the area of public health
(dichlorvos, Abate, and fenthion). A few also find limited use in
home and garden products. Heterocyclic derivatives of phosphorous
compounds are applied in the range of 1 to 5 lb/A. Examples are:
Co-Ral (coumaphos), Dursban, diazinon, Guthion (azinphosmethyl),
and several others of lesser importance.
A second group of organic phosphates is the phenyl derivatives. Ex-
amples of this group are: Nitrox (methyl parathion), Thiophos (para-
thion), Ronnel, Baytex (fenthion), Abate, Ciodrin, plus a large num-
ber of lesser importance. Application rates of these compounds are
typically in the range of 0.5 to 2 lb./A.
The third class of organophosphorous compounds is the aliphatic
derivatives. This group includes such compounds as Dylox (trichlor-
fon), Dibrom (naled), Vapona (dichlorvos), Phosdrin (mevinphos),
Bidrin (dicrotophos), Systox (demeton), Thimet (phorate), Meta-
Systox-R (oxydemetomethyl), malathion, Cygon (dimethoate), plus
a number of others. These compounds are recommended to be used in
the general range is 1 to 5 lb./A.
c. Carbamate insecticides.—The carbamate insecticides are of com-
paratively recent development and represent a unique class of insecti-
cidal compounds of considerable diversity. These apparently owe
their activity to action against the enzyme, cholinesterase, as do the or-
ganophosphates. However, unlike the phosphates, they are competitive
rather than irreversible inhibitors of this enzyme. They are rapidly
detoxified and eliminated from animal tissues and, thus are not ac-
cumulated in fats or excreted in milk. One of the surprising features is
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the synergistic action of carbamates which results from their combi-
nation with piperonyl butoxide, sesamex, sulfoxide, MGK 264, and
other materials used as pyrethrin synergists.
The carbamates act by contact or stomach poisoning and are not
fumigants or vapor toxicants. Their major area of use is on agricul-
tural crops where recommended application rates range from 1 to 10
lb./A. The chief exception is Baygon, which is restricted to use by pest
control operations for spot treatment in the control of cockroaches and
other pests of public health importance. Other examples of carbamate
insecticides are: Bux-10, Furadan (carbofuran), Lannate (methomyl),
Sevin (carbaryl), Zectram, and several others of lesser importance.
d. Miscellaneous insecticide compounds.—There are several insecti-
cides available that do not fit in the above-mentioned groups. They
typically have a more limited activity spectrum and tend not to be as
widely used. This group includes such materials as creosote and penta-
chlorophenol, which are used primarily to prevent termite damage to
fence posts and foundations. Compounds of the nitrophenol group,
such as dinitrocresol and dinitrobutylphenol have limited use in
agriculture at 1 to 3 lb./A.
Several fumigants are available and are used both in agriculture and
for public health. These include methyl bromide, hydrogen cyanide,
and para-dichlorobenzene, which are applied at about 1 lb,/1000 cubic
feet of area. Fly sprays for use around the home and also in livestock
structures may contain organic thiocyanates, Lethane, or Thanite.
Fungicides and bactericides.—These chemicals are toxic to fungi
and bacteria. With plant diseases, these chemicals act to prevent the
plant from suffering detrimental effects of the particular disease.
To be effective, the fungicide or bactericide must be capable of prevent-
ing a disease from becoming established, or arresting the disease if
it is already present. To accomplish this, an effective material to be
used on crops or desired plants must have four attributes, in addition to
relative safety to the crop and low hazard to the consumer of the
product and applicator of the compound: (1) The material must be
able to penetrate the microbial membrane or change these membranes
to establish itself at the active locus; (2) it must enter into reaction
with normal cell metabolism to disrupt the biochemical processes of
the cell essential to its growth and functioning; (3) the toxicant must
be selective so it will not enter into extraneous reactions in the plant
cell and become detoxified or become attached to relatively inert cell
structures such as spore wall; (4) the molecule must be sufficiently
stable to permit its effective use as a spray deposit, chemotherapeutant,
or as occurs in a few examples, to generate fungitoxic decomposition
products as required.
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The discussion of fungicides and bactericides in use today can best
be accomplished through a classification based on chemistry. As with
other pesticides, antimicrobial action can be related to molecular
composition.
1. The inorganic fungicides are the oldest known fungicides and,
despite the onset of new synthetic organic compounds, are still relied
on by many growers. Their use is almost completely restricted to agri-
culture, with some application in the golf course and turfgrass indus-
try, but with only minor penetration in the home and garden market.
Recommended rates range from 1 to 20 Ib./A. Examples of inorganic
fungicides on the market are: Bordeaux mixture, copper sulfate, cop-
per oxide, copper zinc chromate, sulfur, lime sulfur, mercuric chloride,
Clorox, cadmium chloride, plus a few other related compound
mixtures.
2. Considerable effort has been expended on the development of
antibiotics as fungicides and bactericides to control diseases of plants.
A number of effective materials have been discovered but have not been
reduced to commercial use. One of the major problems has been photo-
toxicity. Agrimycin (streptomycin) is a bactericide that has proven
itself to be an effective control agent when used anywhere from 0.5 to
200 Ib./A depending upon the target bacterial disease. Actidone (cyclo-
heximide) exhibits similar activity as a fungicide when used in a
range of 5 to 100 grams per 100 gallon spray solution.
3. Organic mercury compounds are used as fungicides for seed treat-
ments and for bulb and corm treatments. A few organic mercury com-
pounds are used as foliar sprays. Areas of use are chiefly agriculture
with a small market in the specialty area; i.e., golf courses and sod
industry. Examples of products using organic mercury formulations
are: Phenyl mercuric acetate, Semesan, Ceresan M, Panogen, Chip-
cote 25, Emmi, and Memmi. Recommended treatment rates of these
compounds range from 0.25 to 5 ounces per bushel of seed or 0.5 to
5 lb,/A.
Several metal organic fungicides are available and used chiefly for
treatment of handling, harvesting, and storage equipment. They also
are used to prevent rot and mildew in wood and fabrics. These products
are recommended to be applied to a 1- to 5-percent solution. Examples
are: Copper naphthenate, copper oxinate, quinolinolate, and Du-Ter.
5. The dithioaarbannate fwngickles have their greatest use for foliar
disease control of agricultural crops. Many are also effective when
used as a soil drench. Recommended rates of application range from
1 to 15 l'b./A. They are, for the most part, the metallic salts of dithio-
carbamic acid derivatives. The metallic salt form provides them with
the necessary stability to remain effective long enough to control the
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target disease organism. Examples of dithiocarbamates being used
today are: Yapam (SMDS), Zerlate (ziram), Parzate (nabam), Man-
zate (maneb), Dithane Z-78 (zineb), Arasan (thiram), Fermate
(ferbam), and Poly ram (metiram).
6. Chlorine-containing fungicides are effective against a large num-
ber of agricultural crop diseases. They may be used as foliar sprays,
soil drenches, seed treatments, or dormant sprays. They are effective
against turf diseases, powdery mildew, scab fungi, and several other
pathogens. Depending on the compound, they are used at rates ranging
from 0.25 to 5 or 10 lb./A. Examples of this class of fungicides are:
Penta (PCP), Terrachlor (PCNB), Hexachlorobenzene, Captan,
Difoltan, Phaltan (folpet), Phygon (dichlone), Lanstan, Spergon
(chloranil), Dyrene, Daconil 2787, Terrazole, Demosan, and Botran
(dichloran).
7. There are a number of fungicides of variable chemical nature
that fall into a miscellaneous grouping. They are used both in agricul-
ture and in the sod and turf industry. Recommended rate ranges are
from 0.2 to 3 lb./A. Examples are: Karathane (dinocap), Morocide
(binapacryl), Dexon, Cyprex (dodine), Diphenyl, Dowcide A, Glyo-
din, Morestan, and Creosote.
Herbicides, defoliants, and desiccants
There are almost 100 different chemicals and combinations of chemi-
cals that are used effectively as herbicides. There are three basic types
of herbicides depending upon their effects on plants: Contact, systemic,
and soil sterilants.
Contact herbicides kill plant parts through direct contact with the
foliage. Generally the effects are acute and the plant dies quickly.
Contact herbicides may be selective in their action or they may be
nonselective and kill all plants.
Systemic herbicides can be absorbed by either the foliage or the
roots and may be translocated through the entire plant system. They
are usually selective in their toxicity and they usually have a chronic
effect on susceptible plants.
Soil sterilants are chemicals which prevent plant growth when
present in the soil. The length of time for effectiveness may range
from less than 48 hours to more than 2 years.
The greatest area of use of herbicides is in agriculture, although,
considerable amounts are used in maintenance of rights-of-way, water-
ways, maintenance of industrial areas, in the home lawn and garden,
and by various Governmental agencies.
1. Inorganic herbicides are derivatives of inorganic acids where
hydrogen has been replaced by a metal. In sufficient concentration these
provide a contact burning effect. The rates of application are usually
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high, ranging from 100 to 1,200 lb./A. Examples are: Sodium arsenite,
calcium arsenate, sodium chlorate, and sodium borate.
2. Metal-organic compoundh include those having a metal ion com-
plex combined with an organic portion of the molecule. These com-
pounds are usually used to control large areas of weeds such as on
railroad and highway rights-of-way. A few are selective and are used
to control crabgrass in desirable turf lawns. Examples are: Disodium
methane arsonate, cacodylic acid, phenyl mercuric acetate, and several
other similar products.
3. Carboxylic aromatic herbicides.—This large group of synthetic
herbicides has chemistry with two characteristic moieties, a carboxyl
group and an aromatic group. Their activity includes contact, systemic,
and soil sterilant action, depending upon the compound and the rate
and method of application. They can be divided into five types:
Phenoxy acids, phenylacetic acids, benzoic acids, phthalic acids, and
phthalamic acid herbicides.
a. Phenoxy herbicides are a selective group of compounds used
for broadleaf weed and woody plant control. They are systemic in
nature and in warm moist soil persist 30-60 days. They are only
slightly toxic to man and other animals. Examples are: 2,4-D, 2,4,5-T,
silvex, sesone, MCPA, erbon, dichloroprop, and others. The recom-
mended rate range for use is from 0.25 to 2 lb./A.
b. Phenylacetic acid.—The single phenylacetic acid of note is
fenac. It is used at 4 to 20 lb./A for a variety of purposes including1
agriculture, aquatic weed control, and right-of-way weed removal. It
is more persistent in the soil than the phenoxy herbicides but would not
be expected to accumulate from 1 year to the next. It also has a low
toxicity to mammals,
c. Benzoic acid compounds.—The benzoic mid herbicides have a
longer soil persistence than the phenoxy compounds and have a low
toxicity to mammals. Their major use is in agriculture where they are
effective against annual and perennial broadleaves and grasses. Several
show some crop selectivity. Examples are: Amiben, Banvel D (di-
camba), Benzac (PBA), and Trysben (2,3,6-TBA). Application
rates range from 1 to 4 lb./A.
d. Phthalic add compounds.—The phthalic acid herbicides are
preemergence herbicides that prevent weed germination. They are per-
sistent for only about 30 days in the soil and they are relatively non-
toxic to mammals. They are used in agriculture at 6 to 12 lb./A. Ex-
amples are: Dacthal (DCPA) and endothall.
e. Phthalamic acid compounds.—The phthalamic acid herbicides
are preemergence compounds with selective activity. They are applied
at 2 to 8 lb./A and are used almost exclusively for agriculture. They
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are relatively safe to humans and other warm-blooded animals. ITo re-
sidual toxicity is expected to remain in the soil from one year to the
next. The best example is Alanap (naptalam or NPA) which is avail-
able in several forms.
4. Aliphatic Acid Herbicides.—The chemicals in this group are ali-
phatic compounds containing a carboxyl group. They are grass killers
with limited toxicity to broadleaf species. At low rates of 3-6 Ib./A
they are agricultural herbicides, but at 10-50 lb./A they are tem-
porary soil sterilants. They are only slightly toxic to humans and
warm-blooded animals and present no health hazard under normal
use. Examples are: Dowpon (dalapon) and trichloracetic acid (TCA).
5. Substituted Phenol Herbicides.—Substituted phenols are used for
contact killing of all weeds hit by the spray. They are applied to rail-
road and highway rights-of-way and industrial areas as well as on
agricultural crops. They are also used as preemergence herbicides.
Their persistence in the soil is only about 3 to 5 weeks, and they are
not translocated in the plant. Examples are: dinoseb (or DNBP)
and pentachlorophenol. Their toxicity to mammals is considered mod-
erate to very toxic.
6. Heterocyclic Nitrogen Derivative Herbicides.—-The heterocyclic
nitrogen derivatives are agricultural herbicides with loTf mammalian
toxicity. When applied at 1 to 4 lb./A, they demonstrate good selec-
tivity, some possessing preemergence and some postemergence activity.
At higher rates of 10 to 40 lb./A, a few are effective soil sterilants.
At rates of less than 4 lb./A and under a warm, moist environment
they seldom persist in the soil for more than 1 year. Examples are
Aatrex (atrazine), Princep (simazine), Milogard . (propazine),
prometone, and amitrol.
7. Aliphatic Organic Nitrogen Herbicides.—Aliphatic organic
nitrogen compounds can be subdivided into three general types: the
substituted ureas, carbamates, and other amides.
a. Substituted Ureas.—Urea is a common agricultural nitrogen
fertilizer. Replacement of some of the hydrogen atoms in the urea
molecule with other substituents has provided a number of effective
herbicides. They are absorbed easiest through the roots and will nor-
mally persist in the soil 3 to 6 months at preemergence rates (1 to 4
lb./A) and up to 24 months at soil sterilant rates (20 to 50 lb./A).
They are relatively safe to warm-blooded animals and fish when used
at agricultural rates. Examples are: Telvar (monuron), Karmex
(diuron), Dybar (fenuron), Lorox (linuron), Cotoran (fluometuron),
Tenoran (chloroxuron),Herban (norea),andTupersan (eiduron).
7>. Carbamates.—A number of carbamates have been proven to
be quite effective as agricultural herbicides when used at rates ranging
from 1 to 6 lb./A. They are most effective in preemergence applica-
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tions, and are relatively nonpersistent in moist, warm soils. Although
a few carbamate herbicides will cause dermal irritations, they are
considered to be moderately safe to humans and warm-blooded ani-
mals. Examples are: Vegedex (CDEC), Chloro IPC (CIPC), Eptam
(EPTC), Tillam (pebulate), Sutan (butylate), Vernam (vernolate),
Carbyne (barban), Ordram (molinate), Avadex (dillate).
c. Other Amides.—There are several amide derivatives used as
herbicides in agricultural and home and garden products. They are
basically preemergent herbicides with a soil persistence of 1 to 3
months at the recommended rates of 1 to 10 lb./A. For the most part
they are only slightly toxic, but one, CDAA, is dermally toxic. Other
examples are: Dymid (diphenamid), Betasan (bensulide), Lasso,
dicryl, Clobber (cypromid, and Stam (propanil).
8. The dinitroanilme herbicides are preemergence compounds effec-
tive against annual grasses and some broadleaf weeds. They are ex-
tensively used in field and horticultural crop weed control and turf.
At the recommended rates of 0.5 to 3 lb./A, in warm, moist soil they
have a persistence of 2 to 6 months. Their toxicity to humans and
warm-blooded animals is only slight, making them safe to handle.
Examples are: Treflan (trifluralin), Balan (benefin) and Planavin
(nitralin).
0. The nitrile herbicides are used for preemergence broadleaf weed
control in small grains and also in orchards and nurseries. Moderately
toxic to mammals, they range in soil persistence from 1 month to over
2 years. The recommended application rates vary from 0.5 to 15 lb./A,
depending upon the compound and desired use. Examples are: Buctril
(bromoxynil), Certrol (ioxynil), and Casoron (dichlobenil).
10. Herbicides falling into a miscellaneous category include uracil
derivatives, chlorinated compounds, aldehydes, and others. The group
includes at least two compounds, paraquat and diquat possessing higher
mammalian toxicity. Others of this group are considered moderately
toxic. They are used in agriculture as well as in industry. Other exam-
ples include: Tordon (picloram), propachlor, Aqualin (acrolein).
Pyramin (pyrazon), Sinbar (terbacil), and bromacil.
Nenwticides
Nematode control requires the use of clean soil, clean planting stock,
and sanitation. Chemicals used to kill nematodes must not only be
efficient for killing the organism, but also must, leave no residues harm-
ful to plants. Preferably they should be easy to apply. The most effec-
tive nematicides have been those with fumigant action. The fumigant
action may come from a gas confined at the soil surface or from volatile
liquid or granular compounds actually placed in the soil. All are poison-
ous to man and animals.
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1. Halogenated Hydrocarbon Nematicides.—These nematicides may
be injected into the soil or they may be gaseous fumigants applied to
the soil surface under gasproof covers. They have a residual activi-
ity of about 1-6 weeks during which time they can be harmful to plants.
They should be regarded as moderately to very toxic to the applicator.
Many are mixtures of two or more active compounds. Examples are:
Dowfume MC-33 (methyl dibromide+chloropicrin, D-D (dichloro-
propane+dichloropropene), Telone (mixture of chlorinated CB hydro-
carbons), Nemagon (dibromochloropane), and ethylene dibromide.
Rates of application recommended for these compounds are 1 to 2 lb./
100 ft.2 of fumigant or 12 to 20 gal./A of soil injected liquid.
2. Organic Phosphate Nematicides.—A special formulation contain-
ing 4 lb./gal. diazinon controls soil insects and ecto-parasitic nematodes
of southern turf grasses. This product, Sarolex, has a recommended ap-
plication rate of 10 to 20 lb./A.
3. Cyanate Nematicides.—Vorlex is a preplant soil fumigant that
controls weeds, fungi, insects, and nematodes. It is a mixture of methyl
isothiocyanate and chlorinated C3 hydrocarbons. This mixture is ap-
plied at about 20 gal./A. At least 2 weeks must be allowed before plant-
ing a crop. No cover or water seal is required.
4- Tkiophene Nematicides.—An example of a thiophene nematicide
is Penphene (tetrachlorothiophene, or TCTP). It is recommended for
controlling a number of nematode pests on tobacco. It kills by fumi-
gant action when injected into the soil at 6 to 8 lb./A. After 2 weeks
the soil must be aerated before the crop is planted.
Rodenticides and mammalian biocides
The interrelationships of man and animals have become increasingly
complex as human populations have increased. As wildlife habitats
have become altered, certain species have established new balances.
Thus some species have substantially increased in population density,
often creating problems that adversely affect man's interests and wel-
fare. There are numerous situations when control of predators and
rodents is essential to protect agricultural and pastoral interests as
well as human health and safety.
Of the various kinds of nuisance, destructive, disease-carrying, or
predatory mammalian pests, rodents are the main targets of control. A
number of chemical control measures have been developed for rodents,
many of which can be used on other mammalian pests such as coyotes,
skunks, raccoons, etc. Compounds which are toxic to rodents are usu-
ally also toxic to humans and should be handled with utmost caution.
J. Inorganic rodenticides.—There are a number of inorganic com-
pounds that are effective against such pests as rats, mice, moles, and
gophers where they are problems. Although most often used as 1 to 2
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percent baits, a few are active as fumigants. Examples of some inor-
ganic rodenticides are: arsenic trioxide, arsenic sulfide, barium car-
bonate, calcium cyanide, zinc phosphide, thallium sulfate, and sodium
fluorosilicate + zinc cyanide.
2. Botanical rodenticides.—Certain plant extracts have toxic ac-
tivity toward rodents when used in baits at 0.5 to 1 percent. One of
these, red squill, is specific for rats and nontoxic to other warm-blooded
animals when used at specified rate ranges. Strychnine in both the
alkaloid and sulfate form is used chiefly in poison baits set for
squirrels, gophers, rabbits, and some lesser pests.
3. Anticoagulant rodenticidea.—The anticoagulant rodenticides are
highly effective in controlling rats and house mice. They are essentially
odorless and tasteless and are effective in low doses. Action is not rapid
and usually 3 to 5 feedings from a 0.5 percent bait is required. Death
is due to internal hemorrhaging. These baits are recommended for
use only in protected situations where access by higher animals is pre-
vented. Examples of this class are: Fumarin (coumafuryl), Diphacin
(diphacinone), Warfarin (coumafene), Pival (2-pivalyl-l,3-inan-
dione),and Yalone (2-isovaloyl-l,3-indandione).
J+. Fluoride Rodenticides.—The fluoride rodenticides are extremely
toxic to warm-blooded animals and their application is restricted to
use by licensed pest control operators. They are odorless, tasteless,
and fast acting, chiefly affecting the heart, with secondary effects on
the central nervous system. Two such compounds are in use: Com-
pound 1080 (sodium fluoroacetate) and Fluoroakil 100
(fluoroacetamide).
¦5. Miscellaneous Rodenticides.—There are a few other rodenticides
available with a greater degree of selectivity toward rats. One of
these, ANTU (2-napthylthiourea) is specific for the Norway rat when
used as a 1 to 2 percent bait. Another is a specific single dose rat
poison for Norway and roof rats. This compound, Raticate (nor-
formide), is said to be nontoxic to a large number of other warm-
blooded animals.
MoMuscicides
There are several invertebrate poisons used to control molluscs
where their presence is undesirable. They are relatively specific and
are essentially nontoxic to fish and warm-blooded animals.
Polystream is a mixture of chlorinated benzene fractions that is
effective in oyster beds to control oyster drill, a predatory snail.
Bayluscide (chlonitralid) is used to control snails and lamprey in
flowing streams.
Matacil (aminocarb) is a carbamate insecticide that is also very
effective in controlling garden snails and slugs.
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Metaldehyde is a component of slug and snail baits that acts both as
an attractant and toxicant. It may be formulated with or without
calcium arsenate.
Piscieides
The use of piscicides is restricted to game and fish management for
improvements to public waters. The main objective is to remove rough
or trash fish prior to restocking lakes and rivers with more desirable
game fish.
Most widely used for this purpose is rotenone, a highly toxic fish
poison. Used in low dosages, it stuns the fish. As the fish surface,
desirable species are seined out and placed in fresh water tanks where
most revive. A second Jake application kills undesirable fish.
The antibiotic antimycin is finding increasing use as a fish toxicant.
Lampricide L-30-F (3-trifluoromethyl-4-nitrophenol) has been
used extensively in stream management to control populations of
lamprey.
Toxaphene has also been used oil occasions as a means of killing
undesirable fish in water management programs though it is not reg-
istered for the use and the manufacturer discourages it.
Amcides
Some of the most difficult control problems concern birds in cities,
at airports, around homes, and those which gather in great flocks and
cause damage to grain crops, animal feedlots, truck and fruit crops.
Some of the more troublesome species are pigeons, gulls, starlings,
and blackbirds.
Avitrol (4-aminopyridine) controls nuisance and destructive birds
as a treated grain bait. It causes individual members of the flock to
utter distress cries which, in turn, causes other members of the flock
to leave and avoid the "undesirable place." It is used to control pigeons
around city buildings, gulls at airports, and starlings in feedlots.
Another compound, Queletox (a formulation of Baytex insecticide),
is also used to repel birds by affecting a few individuals which frighten
others away.
Also used for bird control because of their repellent action are
imthraquinone and thiram. Thallium sulfate may be used in a bait to
control starlings but is restricted to use by Government agencies
because of dangerous cumulative poisonous properties.
Related Materials and Their Uses
REGULATORS OP PLANT GROWTH AND REPRODUCTION
The control of plant growth and differentiation through the use of
chemical substances is a new development. A number of chemicals are
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now known that have ii relatively broad spectrum of effects while
others merely mediate or block specific metabolic pathways. As a gen-
oral class of compounds, the plant growth regulators are considered
to be relatively nontoxic to humans and other warm-blooded animals.
Their persistence in soils is short, only 4 to G weeks.
Auxins.—Synthetic auxins were the first chemical regulators to
find widespread agricultural use. Kate levels of 10 to 50 ppm are use-
ful for promoting rooting of cuttings, setting of fruit, fruit thinning,
delaying prelmrvest drop of fruit, and for control of flowering of
pineapple. p]xamples of synthetic auxins in use today are: /?-indole-
butyric acid, m-napthaleneacetic acid, /3-napthoxyacet-ic acid, />-chloro-
phenoxyacetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-T,
and silvex.
Gibberellimji,—A large number of varied respotises in plants are as-
sociated with the gibberellins. There is marked stem elongation; over-
coming of physiological and genetic dwarfism; acceleration of flower-
ing in cold-requiring biennials and long-day plants; promotion of
fruit setting; fruit enlargement; elimination of seed, bud, and vegeta-
tive dormancy; promotion of lateral bud growth; seed germination;
and growth at suboptimal temperatures. Rates of application vary
with the effect desired and may be from 1 to 3,500 ppm. The chief
example is gibberellic acid (gibberellin A3).
Oytokinins,—These compounds are of relatively recent origin with
their use potential being limited to favorable effects of prolonging
storage life of green, leafy vegetables and possibly in the enhance-
ment of fruit setting. They are applied at rates of 5 to 10 ppm and
are often combined with one of the other kinds of growth regulators.
Examples of the cytokinin group are: Nc-benzyladenine, Ne-benzyl-
9-tetrahydropyranadenine, and zeatin.
Growth RetardantH. The growth retardants, or inhibitors, may be-
come useful in the growing and handling of crops and in reducing
woody plant growth. They inhibit sprouting of onions and potatoes
in storage; they increase wheat yields by increasing tillering and
stimulating shorter and thicker stems to reduce lodging. A few are
used extensively to control growth of flowers and ornamentals. They
may increase cold resistance. Examples of growth retardants are:
maleic hydrazide, Cycocel, Alar, and Phosphon.
Chemical Repellents
Repellents have two principal advantages: since they need not kill
the pest species, the best repellents have low general toxicity and may
be used safely on man, beneficial animals, and food plants; and they
can provide protection for an individual man, animal, or plant with-
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out the necessity of destroying a huge segment of the pest populations,
with all the expense, difficulty and even hazard that this may involve.
Repellents also have some disadvantages. Because the pest population
is not destroyed, but only held at bay, the host must be completely
and continuously covered with the repellents to obtain protection.
Usually the repellents that protect man and animals are lost rapidly
by abrasion, evaporation, and absorption through the skin, necessitat-
ing re-treatment at. intervals of a few hours or days at most.
The uses of repellents include protection for domestic animals from
biting flies. These may be combined with a low level of pyrethrins.
Man uses repellents to help ward off biting and disease-carrying in-
sects such as mosquitoes, flies, and ticks. Repellents are also used to
prevent pests from infesting certain areas such as food and drink
containers, as well as termite-susceptible structures.
Some insect repellents available are: Ethyl hexanediol (6-12),
N, N-diethyl-m-toluamide, butoxy propylene glycol, dibutyl succinate,
and octyl propyl sulfoxide.
Attractants
Chemical attractants and associated agents serve useful purposes
as lures in traps. As insect attractants they are used to detect pest
infestations, estimate population densities and aid in control of the
pest either through traps or incorporated into poison baits.
Some chemical attractants are biologically active in extremely small
quantities. This is particularly true for those associated with sexual
behavior. Others are apparently feeding attractants. Although not
always true, insect attractants are usually quite specific for a given
species and often for a single sex of the species.
There are at least seven synthetic attractants available for use in
control of fruit flies and melon flies. They are methyleugenol, anisyl-
acetone, cuelure, siglure, medlure, and trimedlure. These have been
very effective in aiding with Mediterranean fruit fly control. Other
attractants are gyplure, bombykol, butylsorbate, and methyllinolate.
Legislation and Regulation Relating to Pesticide Production
and Use
Experimental labels, as currently administered, offer an opportunity
for a manufacturer to place a relatively small amount of a product
on the market in order to better determine the acceptance of the prod-
uct in the market and the need that it may or may not fulfill in the
marketplace. The advantages of this approach are that:
1. The manufacturer can get an early assessment of the future of
the product which may help him determine the amount of investment
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he must make in new manufacturing plants and further product
developments; and
2. It permits the regulatory agency to have a close look at any
problems that may be encountered by the product. Efficacy or safety
deficiencies will likely be brought out by the experimental label pro-
cedure without an overwhelming liability to the manufacturer or
threat to the environment or populace.
In recent years experimental labels have been more widely used.
Under present procedures it is necessary to account for all material
placed under the experimental label and to provide biological results
on the material used. This procedure is helpful, but a further stop
appears in order; namely, the limited sale in regular commercial
channels without the requirement of biological results on the material
should be permitted or even made mandatory for 1 year prior to a
full registration. This would go even further toward enabling the
manufacturer to assess the product in the marketplace but with a
limited exposure on his part, and would similarly provide the regula-
tory agency with a greater opportunity to assess possible threats to
man or his environment. The experimental label is not now a man-
datory procedure, though it is becoming much more widely used. If
the limited label concept is instituted, it is proposed that the limited
label be mandatory but that the experimental label remain discre-
tionary on the part of the applicant.
Improved Label Clarity
Efforts should be made to achieve label clarity. The purpose of the
label on pesticide containers should be to identify the product, explain
the use, and provide adequate directions for use and sufficient pro-
tection for the applicator. Specific improvements recommended for
greater clarity are:
1. The use of the product should be prominently displayed on the
front panel in language familiar to the consumer; such as, "Weed
Killer," "Insect Killer," "Growth Regulator," etc.
2. The ingredient statement should be simplified. It should use com-
mon names only (and every active ingredient should have a common
name) with no reference to chemical names as a footnote outside the
ingredient statement, no reference to licensing agreements, no patent
declaration, and no conversion to equivalents within the ingredient
statement. Otherwise, the style for the declaration of ingredients
could remain identical to current requirements of USDA. The entire
ingredient statement should be printed in such a way as to stand out
from the rest of the label copy; i.e., printed with a contrasting
background.
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3. The label should specify what the product will and will not do.
Organisms to which the product is hazardous should be indicated.
For example, if a compound is known to be very toxic to specific
types of animals such as fishes or birds this information should be
highlighted on the label.
4. The label should be dated in some manner—date of manufacture;
ail expiration date based on product shelf life or stability; or, at the
least, the date of label registration expiration.
5. It is recommended that an entirely new scheme of denoting
relative toxicity be devised. The average consumer does not understand
the progression from caution, warning, to poison. A graphic or numer-
ical representation of the degrees of oral and dermal toxicity should
be developed to enable consumers to select less hazardous materials.
Professional graphic communicators should be consulted on this
project. Cautionary statements should clearly indicate the hazards
without undue cautionary statements.
6. The manufacturer should be responsible for providing, on the
label, information on how to handle spillage and other accidents.
Complete instructions on the disposal of excess material and empty
containers should be provided.
Consideration of Experimental Stock m Commercial Channels
During the past quarter century of intensive organic chemical
pesticide development, many products and product forms have been
placed on the market. Today, with greater knowledge and better ana-
lytical tools, regulatory agencies would probably not allow some prod-
ucts on the market at all. Other products would require much more
restrictive labels. The problem is especially acute in the area of home-
owner products, where some highly toxic materials have been made
available to the homeowner in small packages and where other prod-
ucts have borne unrealistically restrictive labels such as "Wear rubber
gloves, mask and goggles," or "Wear protective clothing." Problems
of shelf life, chemical stability, and physical stability have undoubt-
edly arisen in many of these products. Packaging materials of several
years ago may be less satisfactory than would be permitted today.
At the present time, all pesticide products are registered with the
USD A for a 5-year period. This expiration date does not now appear
on the label. If it did, all obsolete stock not bearing a valid expiration
date should be collected and disposed of. Collection, of course, causes
the problems of financial responsibility to be brought forth. In many
cases the product might be returnable to the manufacturer. In cases
where companies have gone out of existence, some other means of
indemnification at public expense should be considered. It is impera-
tive that a realistic and workable collection and disposal system for
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both pesticide and containers he established, and it is suggested that
our present county agent system for rural areas and public health
officer system for urban areas might be the appropriate collection
center. The removal of all obsolete stock from commercial channels
would permit much better regulation of new products and would re-
move many potential hazards from the marketplace.
Problems of Introduction of New Pesticides—Costs
The development cost for any new pesticide is influenced by a num-
ber of factors. Some of these are related to the nature of the chemistry
of the pesticide; but the most important influences on cost are those
caused by the nature of our economy; i.e., labor costs, equipment cost,
facilities overhead, etc., and the intended use of the new pesticide; i.e.,
focxl crop or nonfood-crop use.
Some insight into the cost of developing a new pesticide can be
gained from a review in a recent publication on R & D costs which
appeared in the April 26, I960, issue of Chemical Week, page 38, The
following table outlines costs for various stages in pesticide develop-
ment and indicates the odds of reaching each stage.
Step
Average
cost per
compound
Chance of
reaching
next step
Cumulative
Total
R. & D.
cost
Synthesis and initial screening.
$400
1:100
1:100
$40, 000
Toxicity testing . _ _
100, 000
1:10
1:1, 000
1, 000, 000
Field evaluation.
400, 000
1:4
1:4, 000
1, 600, 000
Product development -
200, 000
1:2
1:8, 000
400, 000
Process development and
pilot plant, _ _
200, 000
1:1. ")
1:12, 000
300, 000
Test marketing -
200, 000
1:1. 5
1:18, 000
300, 000
Commercialization . -
1 1, 000, 000
1:2
1:36, 000
2, 000, 000
Totals___ ,
2, 100, 400 -
r>, 640, 000
Sales over $5 million/year 1:10 1:360, 000
1 This assumes no marketing organization has been established. Otherwise, the commerclalliation step
would be reduced to $200,000. Source: Arthur 1>. Little, Figures arc for 1964, latest year for which they arc
available.
The value given for "toxicity testing" appears to be low, particularly
if a compound is to be used 011 a food crop. The overall figure of $2.1
million per compound appears to be a reasonable one. For pesticides
to be used on nonfood crops, this figure can be somewhat reduced. The
annual outlay for agricultural research by industry was reported at
$478 million in 1965, which represented 56 percent of all funds spent
by government and industry for this purpose (from the National Pro-
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gram of Research for Agriculture, USDA, 1966). Thus, the search far
new, more effective pesticides is an expensive one.
Reduced iiwentivea
An important part of every decision to develop a new pesticide is
the competitive situation in the marketplace. Quite obviously a new
compound which has better activity, is safer or more convenient to use,
or is less costly than competitive pesticides, has economic advantages
which may make the market attractive. However, in many cases these
factors are unknown or difficult to determine accurately in the early
stages of product development. Thus, a development decision is often
made on the basis of limited knowledge of the true potential of the
compound. Mistakes can be made which add to the development cost
prorated against successful products.
When faced with decisions regarding the commitment of several
hundred thousand dollars to compound development, research manage-
ment often looks to the profitability of the market for the compound.
When faced with such products as 2,4-D (selling wholesale at less than
40 cents per pound) and DDT (at less than 18 cents per pound), man-
agement has difficulty in justifying a large research expenditure for
a compound that has similar biological activity. In addition, if ade-
quate technical support is to be given a new product, there must be
sufficient return to finance such support over at least the initial years
of consumer use when he is learning to use the compound correctly. At
the outset when the ability of the new product to compete with existing
and perhaps lower cost materials is unknown, only those compounds
possessing distinct advantages over existing products have a chance
for success.
Increased regulatory requirements
Regulatory requirements can be expected to be increasingly more
stringent as the years go by. As our technology advances, there will be
many more questions to answer and requirements to be met. Each new
pesticide not only must satisfy existing requirements but in itself
creates new questions which must be answered.
In the quest to learn more about the impact of chemical pesticides
on the environment, there will be new information developed which
may alter present pesticide regulatory requirements. There will be
more interest in persistence, metabolites in plants and soils, water and
air pollution, etc. It can be expected that governmental regulatory
agencies will constantly modify requirements with changing patterns
of agricultural technology and cultural practices. Just as the science
of agriculture changes, the regulations governing pesticide develop-
ment and use will change as needed. We must insure that Buch changes
are well founded and beneficial to agriculture and mankind. Every
79
3711-074 O—6© 7
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technological advance is associated with certain risks. In the final
analysis the benefits to mankind must be weighed against the risks to
mankind.
Multiple regulations
As Federal Government regulatory requirements increase, it is
safe to predict that there will be greater interest on the part of State
and local governments. California has been a leader in the develop-
ment of a state regulatory program; other States have a good begin-
ning, and still others will follow suit. In all probability most State
regulations will follow Federal guidelines and will likely be less
demanding.
Limited markets
Two types of limited markets can be envisioned, one governed by
crop acreage, the other by competition. In the first situation, the crop
acreage potential for the pesticide is so limited as to make the market
too small for an economic return on research cost; e.g., a herbicide for
garlic or turnip greens. In the other situation, a large number of
efficacious, low-cost products on the market so limit the potential for a
new material of equal or slightly better activity that a return on
research investment cannot be realized.
Public reaction
While somewhat unpredictable, we can expect greater awareness by
the public of pesticides and their use. Everyone in government and
industry has a serious moral obligation to deal in facts to the public if
pesticide and agricultural technology are to advance. Reporting and
exaggerating the danger of pesticide usage without equal treatment
of the beneficial aspects of pesticides threatens to retard the advancing
technology required to meet food and public health demands around
the world.
Advantages and Disadvantages of Substitute Methods of Pest
Control
There is growing concern about the distribution of pesticide residues
in the environment the effects of these residues on ecological systems,
and possible effects on human health. Therefore, there is growing
interest in alternative means of controlling pests. Some of the proposed
alternatives themselves present hazards that should be carefully con-
sidered before they are put into widespread use. Our purpose here is
briefly to consider some of the consequences of replacing present
methods of control.
DDT is a very low cost material (17.5 cents per pound, 1968) and
it is unlikely that any effective insecticide will be produced that does
80
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not cost more on a unit weight basis. However, any control method
that does not have to be repeated frequently will cost less in the long
run, and any that do not have the damaging side effects on the environ-
ment that DDT exhibits will have rather intangible values that can at
least partially compensate for greater dollar costs.
It is felt that a reconsideration of cultural controls such as schemes
of crop rotation and trends away from monoculture of single crops
over huge areas is needed. It is widely taken for granted that such
methods would add greatly to labor costs, but we are unaware of any
cost-benefit analyses that have taken account of all relevant factors
including the savings in pesticide costs and the intangible benefits.
More emphasis should be placed on the development of resistant
varieties of crops. This is the only method of control that has proved
feasible against the stem rusts of cereals, and the approach should be
extended to other types of pests. Although, as with the rust fungi, pests
are likely to evolve the ability to exploit resistant strains of crops, the
availability of strains with different patterns of resistance to pests can
greatly alleviate the need for other means of control.
Research should be encouraged on the possibilities of displacing pest
species through competition with innocuous species. For example,
most species of blackflies will not bite man. It is conceivable that some
simple environmental modification could lead to displacement of
noxious forms.
These approaches, together with quarantine regulations and the
synthesis of insect pheromones which would be absolutely specific for
a particular pest species, are not regarded as involving any risks of
undesirable side effects. Some other proposed alternative controls
require further discussion.
Alternative chemicals
As the chemical insecticides currently in use are removed because
they have lost their effectiveness or have been recognized as hazardous,
consideration will be given to replacing them with other chemicals that
may be even more hazardous. For example, parathion is an extremely
poisonous chemical that can be absorbed through the skin. It has caused
a significant number of human deaths when used without proper
precautions.
While most of the organophosphate pesticides usually break down
quite rapidly in the environment they can affect various enzyme sys-
tems in man and domestic animals at very low concentrations. The
effect of prolonged exposure to minimal residues of other pesticidal
chemicals are unknown.
Very little is known about possible synergistic or antagonistic in-
teractions of various chemicals. It is known that when dieldrin and
81
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DDT tire present simultaneously, each affects the storage of the other
in fatty tissue. It has been reported that the presence of detergents in
bodies of water prolongs the residual time of organophosphates. Pesti-
cide residues are believed to have the potential for altering body re-
sponses to drags. These interactions are essentially unpredictable and
difficult to investigate experimentally, but are indicative of the in-
evitable risks involved in introducing new chemicals into the
environment.
Biological control
The principal hazard of introducing predators into ft new region
is the possibility that the introduced species will itself become a pest.
The mongoose was introduced into the West Indies for the purpose to
control rats but it became a scrouge of poultry raisers and of the
native ground nesting birds.
An outstanding success of biological control in Australia was con-
trol of the prickly pear cactus by a moth imported from Uruguay. In
this case, prior to the introduction, Australian scientists carefully
screened various potential control agents and rejected several because
it was found that they would feed on garden crops if they ran out of
cactus.
Care should also be taken with the introduction of bacterial and
fungal diseases to be certain that they are not going to attack bene-
ficial species. For example, the milky disease which is used against the
Japanese beetle attacks beetles of only one family which includes no
species known to be beneficial.
The great merit of biological control is that a one-time application
may permanently solve a pest problem if sufficient care is taken in ad-
vance to be certain of the characteristics of the forms to be introduced.
Another possibility which has not received nearly the attention it
merits is the encouragement of native species which have the potential
for aiding in pest control if ways can be found to encourage increases
in their numbers.
The widespread use of broad spectrum chemical pesticides has
sometimes had adverse effects on biological control. Scale insects which
had been adequately controlled biologically have broken out as a re-
suit of predacious insects being killed.
The sterile male technique
The spectacular success of the program to eradicate the screw-worm
fly in the Southeastern United States by releasing male flies that had
been sterilized by radiation has focused a great deal of attention on
this approach.
82
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In the program against the screw worm fly the males were sterilized
in the pupal stage in the laboratory by exposing them to gamma radia-.
tion. Now proposals are being made for sterilizing insects in the
field with chemosterilants. Some of the chemicals proposed for use
are powerful mutagens and carcinogens that may pose a threat to man
and beneficial organism. Even if chemosterilization were performed
in the laboratory, there seems to be no information about possible
effects on predators eating the sterilized insects.
Miscellaneous controls
Many additional methods of pest control have been proposed but
not yet developed to the point where they can be evaluated either with
respect to benefits or hazards. Ultrasound has been proposed for use
against insects and birds, but possible side effects are unknown.
In the more advanced orders of insects development of the adult
reproductive stage requires the disappearance of a "juvenile hormone."
Thus there is a potential for inhibiting insect reproduction by supply-
ing this hormone artificially. The most obvious side effect is damage to
beneficial insects such as bees, but there may be other effects.
Probably most plants and many animals have developed, in the
course of evolution, specific chemicals that serve as pesticides or re-
pellants. Some such as nicotine, pyrethrum, and rotenone are in use
as pesticides and others such as the oil of poison ivy and the cantharidin
of blister beetles are recognized as hazardous compounds. It seems at
present impossible to predict Avhat new and useful, or potentially
destructive, discoveries may be forthcoming in this field.
Finally, there are possibilities for controlling pests by such devices
as "trap crops" which are so attractive that the pests congregate where
they can easily be controlled. For example, certain pests of cotton
are preferentially attracted to alfalfa. An analogous case involving
animals is the old practice of releasing guinea pigs in buildings infested
with fleas for the purpose of collecting these parasitic insects. One
can imagine that under some conditions trap crops might attract new
pests as, for example, by bringing in undesirable weeds, but such
possibilities seem not to have been investigated.
Appendix
INTERNATIONAL ASPECTS OF PEST
CONTROL BY CHLORINATED HYDROCARBONS
The following breakdown on tonnage basis indicates the relative
importance of insecticides in various crop groups in the world and
83
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the dependence 011 chlorinated hydrocarbons (aldrin, BHC/lindane,
clilordane, DDT, dieldrin, endrin, heptachlor and toxaphene) is evi-
dent from second column (below). The source of this information is
Shell International Chemical Co.'s worldwide usage survey for 1966.
Percent
Total chlorinated
insecticide' hydrocarbon
usage, insecticides
Crop thousand tons in total
Cotton 60.4 38.
Rice 12. 0 57
All other cereals 7. 6 85
Vegetables. 6.8 46
Potatoes 2. 8 61
Sugar beet 2. 4 55
Sugarcane 2. 1 74
Tobacco 2. 0 67
Oilseeds - 1.9 77
Coffee .8 81
Tea... .5 19
Sweet potatoes . 2 92
Fruit including citrus, represent a relatively unimportant use of
chlorinated hydrocarbons (CHI) on tonnage basis due to large
volume of spray oils, however, chlorinated hydrocarbons on olives
rate 55 percent and on vines 16 percent of total. DDT is used on fruit
in Japan, South Africa, Mexico, Italy, United Kingdom, and Argen-
tina, and BHC is used in Japan, India, and Algeria.
Each crop is discussed below in turn
Cotton,—Although only 38 percent of total, the chlorinated hydro-
carbons are essential to this outlet in view of unrivaled cost/perform-
ance effectiveness and also the need to alternate with organo phosphorus
products. Areas of major significance for use of CHI are: Mexico,
Nicaragua, Egypt, Sudan, Brazil, Guatemala, Colombia, Australia,
Turkey, Uganda, Ivory Coast and El Salvador for control of follow-
ing pests: boll weevils, leafworm, lace bugs, stink bugs, cutworms,
thrips, jassids, cotton stainers, tortrix larvae, lygus, mites, army-
worms, white flies, aphids, pink bollworm, spiny bollworm and
loopers, all of which are ubiquitous. Cyclodienes also play part in
control of soil pests such as wireworms (Agriotes), white grubs,
various coleopterious larvae, cutworms, and hylemya, either as seed
dressings or preplanting soil treatments. Cotton losses due to insects
compared with actual production (from Pflanzenschutz Nachrichten
Bayer, 1967) are as follows:
84
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Actual
Estimated
production
actual losses
despite pests
due to Insects
Percent total
Area
(thousand tons)
(thousand tons)
lost to Insects
(A)
-------
testation not severe) myriads, lepidopterious larvae, and tipulidae in
India, U.K., Mexico, Hautevolta/Niger, and Turkey. However, for soil
pest control, e.g. wireworms, white grubs, crickets, cutworms, coleop-
terous root worms, dipterous root worms, of which first four are
ubiquitous, there is really no substitute performance-wise for cyclo-
dienes aldrin, lieptachlor and dieldrin. Thus, these products are essen-
tial for these crops in France, Colombia, Chile, Mexico, Turkey, Spain,
India, Argentina, East Africa, Japan, and Greece. Aldrin or dieldrin
seed dressings give protection at extremely low cost and without risk
of phytotoxicity to large areas of cereal crop and are valuable produc-
tion tools especially in Argentina, Turkey, East Africa, Greece, India
with particular reference to wheat.
Losses due to insects for wheats oats, "barley, rye:
Actual Estimated
production actual losses
despite pests due to Insects Percent total
Area (thousand tons) (thousand tons) lost to Insects
(A) (B)
Central Amerioa 2,403 164 6.0
South America 15,977 867 5.1
Europe 129,049 4,940 3.7
Africa 9,645 1,437 13.0
Asia 42,753 2,978 6.5
Oceania 1,374 837 37.8
Total 201,201 11,213
Losses due to insects for millet and sorghum:
Area
Actual
production
despite pests
(thousand tons)
(A)
Estimated
actual losses
due to Insects
(thousand tons)
(B)
Percent total
lost to Insects
Central America
South Amerioa 1,180 120 9. 2
Europe.. 250 23 8.4
Africa 18,200 3,316 15.4
Asia . 19, 920 3,162 13.7
Oceania 219 22 9. 1
Total 39,809 6,643
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Losses due to insects for maize:
Actual Estimated
production actual losses
despite pests due to insects Percent total
Area (thousand tons) (thousand tons) lost to Insects
(A) (B)
Central America... 8,450
South America 19, 057 6, 353 25. 0
Europe 28, 324 1, 647 5. 5
Africa 14, 920 9, 503 38. 9
Asia 16, 510 2, 620 13. 7
Oceania 200 12 6. 0
Total 87,461 20,135
Vegetables (excluding potatoes).—BHC is important in India,
Japan, Mexico, Spain, but again where soil pests; e.g. agriotes, agrotis,
hylemyia sp. gryllotolpa, and melolontha, need to be controlled cyclo-
dienes are not replaceable on grounds of performance and lack of
taint. Thus in crops, e.g. onions, tomatoes, cliilies, and cabbage, where
residue levels are acceptable, cyclodienes are important in Japan, Italy,
Spain, 'France, and Portugal. DDT for control of cutworms, boll-
worms, white flies, jassids, fruit borers, webworms, cabbage moth, flea
beetles, weevils, and army worms is important in Mexico, Spain, Japan,
India, Chile, ILK., Thailand and South Africa.
Vegetable losses due to insects:
Actual Estimated
production actual losses
despite pests due to insects Percent total
Area (thousand tons) (thousand tons) lost to Insects
(A) (B)
Central America 5,000 639 11.3
Europe 26, 645 866 3. 1
Africa 52,994 7,413 12.3
Asia 61,258 9,209 13.1
South America 35, 326 2, 634 6. 9
Oceania 836 104 11. 1
Total 182,059 20,865
Potatoes including sweet potatoes,—Potatoes are heavily depend-
ent on cyclodienes for control of wireworms and other soil pests and
there are no suitable replacements. BHC is little used due to taint.
Areas of importance for soil pest control include France, Spain, Bra-
zil, Colombia, Peru, United Kingdom, Japan, Greece and Taiwan.
87
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Foliage use of DDT is prevalent in Brazil, C-olombia, Mexico, and
Australia against thrips, tuber moth, armyworm, blister beetle, flea
beetle and Colorado beetle.
Lohs due to insects:
Area
Actual
production
despite peats
(thousand tons)
U)
Estimated
actual losses
due to insects
{thousand tonB)
Percent total
lost to insects
Central America 537 108 16. 7
South America 7,942 1,022 19.5
Europe 141,543 9,904 6.5
Africa 1,760 782 30.8
Asia 11,600 2,035 14.9
Oceania- 720 74 9.3
Total 164,102 14,825
Sugar beet.—In view of nature of the crop cyclodienes (aldrin and
heptachlor) again are very important for control of soil and ground
surface pests such as agriotes, agrotis, gryllotolpa, melolontha, blani-
ulus guttulatus (millipedes), lixus, cleonus and pegomyia, particularly
in Belgium, Italy, France, Spain, Greece, Chile and Turkey. Use of
CHI seed dressings are essential when considering germination re-
quirements of modern monogerm seeds, e.g. in U.K.; seed dressing in
other areas, e,g, Turkey, are also important aspect where estimated
75 percent are treated this way. BHC use is important for cleonus,
armyworm and beetles in Italy and Turkey and DDT is important in
Turkey and Spain for similar pests.
Sugar beet losses due to insects:
Actual Estimated
production actual losses
despite pests due to insects Percent total
Area (thousand tons) (thousand tons) lost to Insects
(A) (B)
Central America
South America 1,034 229 18.1
Europe 100,080 6,057 5.7
Africa -
Asia-. 7,440 3,449 31.7
Oceania
Total 108,654 9,735
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Sugarcane.—BHC/lindane are dominant here and important in con-
trol of leaf hoppers, white flies, termites, soldier fly (Australia),1
borers and cane beetles, in Mexico, Australia, India and Brazil. Endrin
is important in certain areas; e.g. Ivory Coast, Taiwan and India, for
borer control. Also, dieldrin is particularly relevant in South Africa
where heteronychus licus is not controlled with any other product.
Aldrin and heptachlor are important for soil pest control in India,
Brazil, Mexico, Pakistan and Taiwan.
Sugarcane losses due to insects:
Actual Estimated
production actual losses
despite pests due to insects Percent total
Area (thousand tons) (thousand tons) lost to insects
(A) (B)
Central America.. — 101,942 15,446 13.2
South America 117,070 31,358 21.1
Europe 410 27 6.2
Africa 30,000 15,450 33.3
Asia 188,120 134,372 47.7
Oceania _ 17,670 2,677 13.2
Total 456, 112 199,330
Tobacco.—Foliage pests such as leaf worms, bollworma, thrips, horn-
worms, flea beetles, leaf miners, stink bugs, cutworms necessitate use
of DDT in Mexico, Australia, South and East Africa. Likewise small
quantity of BHC is used mainly in Mexico. Soil pests as previously
listed are important in Japan, Italy, South Africa, Mexico, Colombia,
Greece, and Spain, where cyclodienes are used instead of above two
products, especially where wireworms are present.
Tobacco losses due to insects:
Area
Actual
production
despite pests
(thousand tons)
(A)
Estimated
actual Josses
due to Insects
(thousand tons)
(B>
Percent total
lost to Insects
Central America 247 41 14.2
South America.- _ 244 77 24.0
Europe 704 46 6. 1
Africa . 260 57 18.0
Asia 1,460 218 13.0
Oceania. 18 4 18.2
Total % 033 443
1 Due to resistance can now be controlled only by dieldrin.
89
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Oil Seeds.—These crops including sesame, soybeans, groundnuts,
sunflower, etc. are again heavily dependent on CHI. BHC is important
in India and Japan while DDT is used in Argentina, Brazil, India,
Japan, Colombia, and Nicaragua, Toxaphene also is important in
Colombia, France, Brazil, and Venezuela against lepidopterous larvae,
earworms, army worms, and loopers.
Losses due to insects:
Actual Estimated
production actual losses
despite pests due to insects Percent total
Area (thousand tons) (thousand tons) lost to insects
(A) (B)
Central America 2, 854 255 8. 2
South America 5,614 381 6.4
Europe 5,095 1,378 21.3
Africa 8,785 2,269 20.5
Asia 19,765 4,971 20.1
Oceania 366 91 19.9
Total 42,479 9,345
In addition to crop aspects there are certain other specific pest
problems to be taken into account:
Locusts.—Total world annual value loss is estimated at $1 billion
(Bayer 1967). In Asia and Africa more than 60 countries are liable to
invasion by locust swarms. Medium-sized swarm may contain 3 billion
locusts and consume 3,000 tons of food/day ("Pests and People,"
Shell). Several figures for value of crops destroyed in India, Kenya,
Morocco, Libya, Sudan, Senegal, Ethiopia, India between 1928 to 1962
are available if required (Anti-Locust Research Centre London, Hand-
book). Recession of swarms was experienced from 1962 to 1968 but
then a further outbreak started in 1969. However, this was checked
and 1969 now is unlikely to become a plague year due to spray cam-
paigns using BHC and dieldrin. The latter is still very important
for control of hopper bands. Other insecticides including organo-
phosphorus materials either are not so effective or more expensive.
Termites.—Total world annual value (excluding damage to wood-
work, buildings, etc.) is $165 million (Bayer 1967). Annual expendi-
ture in Australia for repairing damage done by termites is 3 million
A. pounds (Pans February 1965, vol. 2). Termites in agriculture are
covered where important in earlier sections. Nonagricultural use of
aldrin/dieldrin is particularly relevant in building construction where
many architects now specify dieldrin alone.
90
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Yellow fever and malaria.—The main insecticide used against Aedes
aegypti is DDT. One fifth of world's malaria has been eliminated
by use of pesticides (Pans A, Yol. 9, No. 4,1968). In India the number
of malaria cases dropped from 100 million in 1933-35 to 150,000 in
1966, and loss to economy in same period reduced from 1.3 billion
dollars to 2 million (World Health, April 1968). Dieldrin has played
a part in this spectacular progress but DDT is still important in at
least 24 countries for mosquito control and an estimated 16,000 tons
are used annually. This is of particular importance in India, Mexico,
Brazil, Venezuela, Columbia, Vietnam, Honduras, and Japan.
Chagas disease.—Kesidual house spraying with gamma BHC and
dieldrin is successful in Central and South America. At moment, CHI
are particularly important in Venezuela and Brazil.
Sleeping sickness.—This disease is transmitted by the Tsetse. Ac-
cording to "World Rev. Pest Control" (vol. 5, No. 1, 1966) between
1930 and 1946 half a million cases were reported and treated in
Nigeria alone.
Four and one half million square miles of Africa is denied to cattle
and horses with consequent inpoverishment of farming practice. DDT
is used in Nigeria and Zambia but more effective control is obtained
with dieldrin, which is widely used in Nigeria, Tanzania, Kenya,
Uganda, and Zambia. Some endosolfan also used in this outlet. Use
of organophosphorus insecticides is unsatisfactory.
River blindness (Onchocerciasis).—This is spread by simulium fly.
It is of particular importance in West Africa where DDT is used
in Nigeria* Ivory Coast, and Upper Volta.
Wood preservation.—In addition to public health, CHI are valu-
able in certain industrial uses, e.g. protection of wood products against
borers etc., in wood-producing countries.
Twcura (Grasshopper).—This is a particular problem in Argentina,
affecting 15 million hectares of which 7 million are natural grass and
support average of 3 sheep or 0.8 cows/Ha. Eight grasshoppers per
square metre eat equivalent to one animal/Ha. Thus, infested land
in dry years is unable to support stock by mid summer and these have
to be moved at great expense to tucara-free area or sold cheaply for
slaughter. Prior to the use of dieldrin, annual losses of cattle products
estimated at 90 million dollars despite extensive use of BHC. Dieldrin
and heptachlor were banned February 1968 due to residue problem on
USA imports, and subsequently four other products were approved:
Sevin (expensive, difficult to apply), malathion (more expensive than
dieldrin and average in performance) Diazinon (requires removal of
animals from treated area), and Dibrom (requires special equipment).
Sumithion trials were successful, but in practice control was poor,
91
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0U Seeds.—Those crops including sesame, soybeans, groundnuts,
sunflower, etc. are again heavily dej>endent on ("III. BHC is important
in India and Japan while DDT is used in Argentina, Brazil, India,
Japan, Colombia, and Nicaragua. Toxaphene also is important in
Colombia, France, Brazil, and Venezuela against lepidopterous larvae,
eanvonns, army worms, and loopers.
Losses due to insects:
Actual Estimated
production uctual losses
despite pests due to insects Percent total
Area (thousand tons) {thousand tons) lost to insects
{A) (B>
Central America 2, 854 255 8. 2
South America ">,614 381 fi. 4
Europe 5,095 1,378 21.3
Africa 8,7K5 2,269 20. 5
Asia 19,765 4,971 20. 1
Oceania 366 91 19. 9
Total 42,479 9, 345
In addition to crop aspects there are certain other specific pest
problems to be taken into account:
Locwitn.—Total world annual value loss is estimated at $1 billion
(Bayer 1967). In Asia and Africa more than CM) countries are liable to
invasion by locust swarms. Medium-sized swarm may contain 5 billion
locusts and consume ;1,000 tons of food/day ("Pests and People/*
~Shell). Several figures for value of crops destroyed in India, Kenya,
Morocco, Libya, Sudan, Senegal, Ethiopia, India l>etween 1928 to 1962
are available if required (Anti-Locust- Research Centre London, Hand-
book). Recession of swarms was experienced from 19P>2 to 196H but
then a further outbreak started in 1969. However, this was checked
and 1969 now is unlikely to become a plague year due to spray cam-
paigns using BHC and dieldrin. The latter is still very important
for control of hopper bands. Other insecticides including organo-
phosphorus materials either are not so effective or more ex|»ensive.
Termiteft.—Total world annual value (excluding damage to wood-
work, buildings, etc.) is $16.r) million (Bayer 1967). Annual expendi-
ture in Australia for repairing damage done by termites is 3 million
A. pounds (Pans February 1965, vol. 2). Termites in agriculture are
covered where important in earlier sections. Nbnagricultural use of
aldrin/dieldrin is particularly relevant, in building construction where
many architects now specify dieldrin alone.
90
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Yellow few and malaria.—The main insecticide used against Aedex
argifpti is DDT. One fifth of world's malaria has been eliminated
by use of pesticides (Pans A, Vol. S), No. 4,1968). In India the number
of malaria eases dropped from 100 million in 1933-35 to 150,000 in
196(5, and loss to economy in same period reduced from 1.3 billion
dollars to 2 million (World Health, April 1908). Dieldrin has played
a part in this spectacular progress but DDT is still important in at
least 24 countries for mosquito control and an estimated 10,000 tons
are used annually. This is of particular importance in India, Mexico,
Brazil, Venezuela, Columbia, Vietnam, Honduras, and Japan.
Chagax dUc/ixc.- Residual house spraying with gamma BIIC and
dieldrin is successful in Central and South America. At moment, CHI
are particularly important in Venezuela and Brazil.
Sleeping virkns/ift.—This disease is transmitted by the Tsetse. Ac-
cording to "World Rev. Pest Control'- (vol. .1, No. 1, lBfiO) between
11)30 and 1946 half a million eases were reported and treated in
Nigeria alone.
Four and one half million square miles of Africa is denied to cattle
and horses with consequent inpoverishment of farming practice. DDT
is used in Nigeria and Zambia but more effective control is obtained
with dieldrin, which is widely used in Nigeria, Tanzania, Kenya,
Uganda, and Zambia. Some endosolfan also used in this outlet. Use
of organophosphorous insecticides is unsatisfactory.
River blind-Mux (Onchocerciasis).—This is spread by simulium fty.
It is of particular importance in West Africa where, DDT is used
i n Nigeria, Ivory Coast, and Upper Volta.
Wood ¦preservation.—In addition to public health, CHI are vahi-
alile in certain industrial uses, e.g. protection of wood products against
borers etc., in wood-producing countries.
Turum (Grasshopper).—This is a particular problem in Argentina,
affecting 15 million hectares of which 7 million are natural grass and
support average of 3 sheep or 0.K cows/Ha. Eight grasshoppers per
square metre eat equivalent to one animal/IIn. Thus, infested land
in dry yeaiw is nimble to support stock by mid summer and these have
to be moved at great expense to tucara-free area or sold cheaply for
slaughter. Prior to the use of dieldrin, annual losses of cattle products
estimated at 90 million dollars despite extensive use of BHC. Dieldrin
and heptachlor were banned February l£>fi8 due to residue problem on
USA imports, and subsequently four other products were approved:
Sevin (expensive, difficult to apply), mahithion (more expensive than
dieldrin and average in performance) Diazinon (requires removal of
animals from treated area), and Dibrom ( requires special equipment).
Sumithion trials were successful, but in practice control was poor,
91
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likewise control by malathion. Carbaryl, Diazinon, Azodrin, Gardona
and Dimethoate gave poor or complete lack of control. At present
there hats been complete withdrawal of all approvals with resultant
confusion. Next season Tucura infestation is expected to be severe due
to lack of control this season, and if conditions are dry national dis-
aster may result. Al>o\e case study clearly underlines the drastic effect
that removal of the one essential agricultural weapon may have 011 an
agricultural economy.
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CHAPTER 2
Contamination
Contents
Page
Summary and conclusions 101
Pesticides and persistence 103
The air route 105
The water route 116
The food route 131
Soil contamination 143
Household use 145
Pesticide manufacture, occupational exposure, and accidents. _ 152
Alternative pest control measures 161
Monitoring of pesticides in the environment 168
Systems analysis of pesticides in the environment 174
99
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CONTAMINATION
SUMMARY AND CONCLUSIONS
The subgroup on contamination has examined the present status of
knowledge on the dissemination of pesticides into the environment, the
mechanisms and rates at which they accumulate in various elements
of the environment, and methods by which pesticides might be con-
trolled so that their presence in the environment would pose a minimal
hazard to society consistent with the benefits to be obtained from
their use.
The subgroup has examined: a) The air route by which pesticides
are applied and distributed in the biosphere; b) the water route;
c) the food route; d) soil contamination; e) household uses of pes-
ticides; f) occupational exposures resulting from the manufacture
and application of pesticides, and accidents that may occur in their
use; g) alternatives to the use of persistent pesticides; h) the monitor-
ing of pesticides in the environment; i) systems analysis of pesticides
in the environment.
Much contamination and damage results from the indiscriminate,
uncontrolled, unmonitored and excessive use of pesticides, often in
situations where properly supervised application of pesticides would
confine them to target areas and organisms and at the concentrations
necessary for their beneficial use without damage to the environment.
Research investigations, demonstrations, and monitored operations
reveal that the careful application of many of the pesticides and the
use of techniques presently available and being developed can be
expected to reduce contamination of the environment to a small frac-
tion of the current level without reducing effective control of the target
organisms.
The present piecemeal involvement of various Federal agencies in
pesticide control requires more than the existing type of coordination.
As human health and welfare are the values of prime concern, the
DHEW should provide a lead in the establishment of a mechanism
for administering pesticide control programs.
Ad hoc studies of pesticides in the environment are not adequate to
assess the inputs of pesticides to the biosphere, their degradation,
translocation, movement and rates of accumulation. Monitoring is con-
ducted by a large number of agencies, but in each instance the monitor-
101
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ing is related to a specific mission of the agency. Therefore, a single
agency should take the initiative to insure the effective monitoring
of the total environment, and the filling of giips in data such as for
oceans and ground water, as they are identified. A continuous systems
analysis of pesticides in the environment needs to be conducted.
Aerial spraying should l>e confined to specific conditions of lapse
and wind that will preclude drift. Regulations to limit aerial applica-
tion to specific weather conditions would be helpful in providing
guidance for regulatory programs. Increased engineering development
effort is needed for the design of equipment for, and the adaptation
of helicopters to the aerial spraying of pesticides.
The use of low volume concentrated sprays should be encouraged.
Since this technique, if it is not properly controlled, can be more haz-
ardous to workers, effective regulations must precede its increased use.
Increased information is needed on the degree of exposure of the
general population to pesticides used for household, lawn, and garden-
ing purposes. More effective means for regulation and control of pesti-
cide use by the general public should be instituted, possibly by licensing
of distribution outlets.
The use of inclane and similarly toxic materials which act by evapo-
ration must be discontinued where humans or foods are subject to
exposure, such as in homes, restaurants, and schools.
There is a vastly increased need for the education of the general
public, in the management of pesticides and in the training of profes-
sional applicators. Public communications media, schools and univer-
sities all have important roles to play.
Labeling regulations must also be improved. Print should be en-
larged and language should be made intelligible for the lay public.
A need exists for nonlanguage, internationally intelligible insignia or
markings that will advise the user of the degree of toxicity and per-
sistance of the product, its method of application, and the target
organisms.
More vigorous effort is needed to replace the persistent, toxic, and
broad-spectrum pesticides with chemicals that are less persistent and
more specific. Certain of the less-persistent pesticides, however, may
be more toxic to humans and therefore effective regulation of their
application is required to insure against injury to personnel.
Integrated control techniques for the control of select pests promises
to effect a reduced usage of pesticides. Such alternative techniques
should be more widely applied.
Licensing of commercial pesticide applicators, as well as other large-
scale applicators of hazardous materials should be required.
Analytical methods, although extremely good, require further de-
velopment. Need exists for standardizing or referencing additional
102
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techniques, even on an international basis. There is need for both
less sophisticated techniques for field use as well as for automated
techniques for wide-so ale monitoring.
Standards for selected pesticides should be included in the Public
Health Service "Drinking Water Standards". Although guidelines
and criteria for some pesticides have been delineated, they have never
been officially established.
Prior to application of pesticides to waters for the control of weeds,
snails, mosquitoes, and in other aquatic uses, a careful analysis should
be made of the proposed pesticide characteristics with respect to the
uses of the target area. Special concern is indicated where domestic
water supply is involved, or where food-chain concentration may
occur.
Steps should be taken to prevent the simultaneous shipment of
pesticides and foodstuffs within the same vehicle. Comprehensive
regulations for pesticide transportation are required.
Safe methods of disposal of pesticides, their wastes, and containers
are needed to prevent the contaimination of the environment and to
protect individuals from contamination and accidents.
Intensified research and development is needed in the following
areas, among others:
a. Prediction of the micrometeorological conditions suitable
for aerial spraying.
b. Application of systems analysis to the pesticide-enviroment
problem.
c. Pesticide chemodynamics, with emphasis on reservoirs of
storage.
d. More intensive development of less-persistent pesticides
with narrow spectra of toxicity.
e. Continuing development of spray devices with narrow
spectra of droplet sizes.
j. Continuing development of alternatives to chemical control
of pests.
g. Creation of more suitable materials for pesticide packaging
and containers to facilitate safe transfer, handling use, and
disposal.
h. Treatment processes for the elimination of pesticides from
domestic water supplies as well as from wastewaters.
i. Immediate studies of the effects of pesticide residues on
algal photosynthetic activity.
Pesticides ajtd Persistence
Any examination of environmental contamination by pesticides must
include a consideration of persistence. Persistence in pesticides may
103
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be benefiicial or harmful. Lasting residuals provide control of target
organisms over longer periods of time and reduce needs for reapplica-
tion. However, lasting residuals may also affect nontarget flora and
fauna for long periods of time.
Major classes of pesticides may be grouped as nonpersistent, mod-
erately persistent, persistent, or permanent. Persistence times are
those periods required for a 5- to 100-percent loss of the pesticides'
activity under normal environmental conditions and rates of applica-
tion (1). Accordingly, nonpersistent pesticides may be characterized
as having persistence times of 1 to 12 weeks; moderately persistent
pesticides, 1 to 18 months; and persistent pesticides, 2 to 5 years. Perm-
anent pesticides are virtually permanent as they are not degraded. The
overlaps and gaps simply illustrate the generality of the above defi-
nition of persistence time. Varying the environmental situation varies
the persistence.
Important nonpersistent pesticides are organophosphorous com-
pounds. They include malathion, methyl parathion, and parathion.
which are widely used for the control of cotton and other pests. Mala-
thion lias also f>een developed for use as an undiluted ultra-low-volume
spray. Another class of nonpersistent pesticides is the carbamates,
which contain neither chlorine nor phosphorus, but are classified with
most of the organophosphates in their low persistence. Oarbaryl is the
most used carbamate and was the third most used insecticide in the
United States in 1964. Cotton, apples, and soybeans accounted for 62
percent of its total agricultural use. Its persistence is approximately
that of malathion and parathion.
Most pesticides fall into the moderately persistent grouping. Nearly
half of the total quantity of pesticide used in 1964 was used on corn,
wheat, and cotton. 2,4—D and Atrazine, together, made up 54 percent
of the total agricultural usage of herbicides in 1964. In 1967, herbicide
sales in the United States exceeded insecticide sales for the first time.
The persistent group of pesticides include most of the chlorinated
hydrocarbons. Of this group, DDT is still the insecticide most widely
used worldwide although the overall demand for DDT. both in the
United States and abroad, has declined. Most DDT exported is used in
malaria-control operations. Within the United States, use will
undoubtedly decline further, especially in view of mounting
restrictions. The cyclodiene organochlorines include aldrin, dieldrin,
endrin chlordane, heptachlor and toxaphene. Aldrin is currently used
as a soil insecticide to control the corn root worm. Dieldrin is used for
the control of pests when a long-lasting residual effect is required.
Toxaphene accounted for about 25 percent of all crop insecticides used
in 1964,69 percent having been applied to cotton.
104
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The permanent group of pesticides are based on such toxic elements
as mercury, arsenic, and lead. Once applied, these materials remain
unless physically removed as by leaching with water. Since their water
solubility is low, they tend to remain where applied.
CITED REFERENCES
(1) Kearney, P. C., R. G. Nash and A. R. Isensee. "Peristenee of Pesticide Resi-
dues in Soils", pp. 54-67, In: M. W. Miller and G. G. Berg, Eds., "Chemical
Fallout", Thomas. Springfield. 111. (1960).
The Air Route
The introduction of pesticides into the environment for the control of
insects or unwanted plant growths is most generally accomplished by
aerial or surface applications. In all such cases, air is the medium
through which pesticides move to their intended targets. The character-
istics of the air medium affects the efficiency of the application on the
target and the dispersion, of the pesticide outside the target area. A
clear understanding of the ways in which air characteristics influence
pesticide applications and of the presence and persistence of pesticides
in air is necessary both for the efficacious application of pesticides and
for the proper control of the possible harmful effects which these toxic
chemicals may exert on nontarget organisms and the human
populations.
In 1963 the State of California used about 20 percent of the total
U.S. pesticide production (1). Approximately 80 percent of pesticides
applied by commercial applicators were applied by aerial treatment
and 20 percent by surface application. Problems associated with the
application of pesticides by aircraft are therefore of primary im-
portance. These considerations include the effect of the aircraft and its
operation on the dispersal of the pesticide and the influence of meteor-
ological conditions on aerial pesticide treatments. In addition, param-
eters such as wind drift, pesticide formulation and particle size, which
are common to all pesticide applications, must be evaluated.
The application of pesticides by aircraft has increased over the last
30 years. Fixed-wing airplanes have been the dominant means of ap-
plication but the use of helicopters has increased and is expected to
increase further. Aircraft have been used to apply dusts, aerosols,
granular materials and sprays.
Regardless of the pesticide formulation, the pattern of release from
fixed-winged aircraft is from the craft into the air wake created by the
wings. The wake carries the material outward to the wingtips, then
drops it in a swath of about wingspan width. Two distinct vortices
develop at the wingtips. The strong central propeller wash skews the
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wake to one side of the aircraft. The velocity of the particles is greater
in the propeller wash than in the vortices. The wake which an aircraft
produces is a function of the weight of the airplane and its load and the
configuration of the wing and external applicating equipment. There-
fore, the lighter and more aerodynamically clean the aircraft, the less
turbulent is the wake and the more efficient and controllable the
application.
The configuration of the particle movement behind a helicopter is
similar to that of winged aircraft. Outer vortices develop but they are
different in intensity due to the change in pitch of the rotor blades.
The velocity of the particles is greater at the center of the rotor than
in the wash created by the outer blades. Contrary to earlier opinion,
the down wash of the helicopter rotor does not, at normal operating
speeds, aid in the application of pesticides. In fact, above speeds of
15-25 mph forward speed, the helicopter does not exert any greater
downwash than a winged aircraft. Only when the helicopter ap-
proaches hovering velocities does any significantly greater downwash
occur. The spray pattern from helicopters is, however, better than that
of an airplane due to the lack of a propeller wake.
The helicopter has other advantages over fixed-wing aircraft. It is
highly maneuverable and is capable of flight at low levels and in moun-
tainous terrain. The helicopter also has the ability to takeoff and
land in small openings and it is not as dependent on airport facilities
as fixed-wing craft. This reduces the turnaround time for reloading
and may overcome the helicopter's two main disadvantages, its high
cost and lower carrying capacity. On flat terrain or over forests where
aircraft must fly faster than 45 mph and at heights of 50 feet or more
above the treetops, slow, low flying fixed-wing aircraft are as efficient
in application as helicopters and are less expensive to operate.
The spraying equipment used on fixed-wing aircraft and helicop-
ters are similar in design. Dusts and granular materials are usually
spread by means of a centrally located venturi device which mixes the
material with air and discharges it into the trailing wake. Sprays are
atomized by hydraulic atomizing nozzles and are distributed through
a wing length boom. Nio benefit has been found by using Ionger-than-
wing-length booms because the aircraft wake limits and controls the
distribution of the particles. Booms are used on both fixed-wing air-
craft and helicopters. Jet type nozzles aimed with the airstream have
been used but produce a relatively coarse spray not suitable for all types
of insecticide spraying. In most forest spraying, standard boom and
nozzle spray systems have been used. They usually deliver 1 gal/acre
at an atomization of 150 to 200 p. mass median diameter with the maxi-
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mum drop size often exceeding 500 p. Aircraft used for low-volume ap-
plications have been equipped with smaller nozzles or mini-spins cali-
brated to release 8 to 16 fl. oz./acre at a slighty finer atomization,
usually 125 to 150 p mass median diameter with a maximum drop size
between 300 and 500 ft.
The atomization during low-volume spraying of mini-spin rotary
units operating at three speeds and of three, small orifice, flat spray
nozzles was investigated by Isler (2). An increase in the rpm of the
mini-spin unit from 4000 to 8000 resulted in a decrease in the average
mass median diameter (m.m.d.) of maltvthion drops from 184 to 120 ju.
The best performing flat spray nozzle exhibited a range of m.m.d. of
112-158 with an average m.m.d. of 128, a value only slightly higher
than that of the mini-spin at 8,000 rpm. The mini-spin, however, pro-
duced a narrower distribution of drop sizes than did the nozzle. At
the low end of the spectrum, 25 percent of the spray volume of the
mini-spin was in drops smaller than 90 p., compared to 42 percent with
the nozzle. The performance of the mini-spin, therefore, was more
desirable than that of the nozzle because it resulted in fewer small
drops which would be subject to drift, and fewer large drops which
would result in overdosing and inefficient spray application. This study
demonstrates that the selection of the appropriate spray equipment is
an important consideration in effectively applying agricultural chemi-
cals.
MwrocUmatology effect.—The dispersal of particles during an aerial
application ia dependent on wind and thermal conditions at the site
of application- At the time of application, calm wind conditions should
prevail to minimize drift and allow for greater control of the pesticide
application. Thermal conditions are also important since temperature
gradients present in the area of application affect the movement and
dispersion of the particles.
Akesson and Yates (3) state that the following measurements should
be made for proper control of spraying: 1) The temperature gradient
between 8 and 32 feet; 2) wind direction and velocity at 8 feet; and
3) the relative humidity at 8 feet. The temperature gradient between 8
and 32 feet will yield information as to the thermal condition present.
There are two main types of thermal conditions. When the temperature
decreases with elevation a lapse condition is said to exist When the
reverse is true and the temperature increases with height from the
ground, the thermal condition termed inversion exists. Under various
combinations of lapse conditions, the main particle movement, is verti-
cal whereas under conditions of inversion the main particle movement
is in a lateral direction. The measurement of the temperature gradient
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between 8 and 32 feet indicates the degree of lapse or inversion con-
ditions which exist. According to Akesson and Yates (
-------
Surface Treatment
Aerial Treatment
BHC 2.6-12.5 mg/m1 air 4.1-53.7 mg/m1 air.
DDT 4.6-25.5 mg/m" air 18.9-170.9 mg/m4 air.
Thus, it is quite evident that the increased use of aerial applications is
accompanied by an increased hazard from drift as well as a possible
loss in the efficiency of the application.
Akesson et al. (6) measured the drift downwind after a DDT
application of 1 lb./acre to 40 acres under both windy and calm weather
conditions. They found the following:
Concentration
(p.p.m.) 100 feet
downwind
Distance (ft.) 0.01
p.p.m. found
downwind
Calm conditions
Windy conditions
1.5
8.0
8, 000
20, 000
The amount of drift, therefore, is highly dependent on wind
conditions.
The amount of drift is also related to the size of the treated area
and to the rate of application of the pesticide. The larger the area
treated, the greater the number of swaths that must be made by the air-
craft and the greater the potential for drift, but the lower the loss per
unit area treated. Also, the greater the application rate, the greater
the residue at given distance downwind.
Gerhardt and Witt (6) compared the drift of spray and dust for-
mulations of DDT and found that under the same climatic conditions
and at an application rate of 1 lb./acre, the spray resulted in a con-
centration of 0.1 p.p.m. DDT 2,640 feet downwind and the dust
1.4 p.p.m. at the same distance. This effect was due to the difference
in particle size between the two formulations, the dust particles being
smaller than the spray droplets.
Yeo (7) studied the effect of liquid particle size on drift and found
that particles of less than 5 p diameter exhibited little deposition and
drifted in air currents for many miles. Particles of 10-50 n diameter
were deposited several miles from the source. Unless the wind was
high, particles of 100 ju exhibited little drift hazard and when the par-
ticles were greater than 200 n diameter, 80 percent were deposited
within short distances downwind. Akesson and Yates (3) studied the
effect of dust particle size on drift and found that when released 10
feet above the ground into a wind 3 m.p.h., 2 p diameter particles
traveled 21 miles, 10 n particles 1 mile and 50 n particles 200 feet.
Akesson and Yates (3) sprayed a field with toxaphene dust and
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spray and measured the drift of each as well as that of fine (95 to
150/u, diameter) and medium size (150 to 300/* diameter) particles. They
found that in all cases the ground fallout due to drift away from the
target area was 4 to 10 times as high for dust than for sprays. Also,
the ground residue from applications of fine drops was twice as much
as medium drops at distances up to 1,000 feet. They also observed that
in some cases, the amount of pesticide in the air downwind was 30 to
40 times that on the ground.
These studies indicate that as far as drift is concerned, the greatest
potential nontarget contamination hazard occurs with smaller diam-
eter particles. Since dusts contain a greater percentage of these smaller
particles than do conventional liquid sprays, dusts constitute a greater
drift hazard than sprays. Sprays, however, are not uniform in drop
size and, with atomizers currently used, there is no way to eliminate
the production of a wide distribution in drop sizes. Both large and
small drop sizes will bo produced. Moreover, the control of drop size
in favor of the larger drops to reduce the drift potential results in a
decrease in the efficiency of spraying since the efficiency is an inverse
function of drop size. More large drops fall to the ground but the
extent of coverage is less. Therefore a compromise in drop size must be
reached between those sizes which minimize drift and a size which
yields a high efficiency of application. Since a wide distribution in
drop size is inevitable with commonly used spray equipment, and fine
drops will inevitably be created, dependence upon large droplet size
to control drift is not appropriate. The measurement of micrometeoro-
logical conditions, therefore, is of paramount importance in determin-
ing the safety of a proposed application.
This point is illustrated by a study conducted by Quinby and Door-
nink (8) in which the absence of wind and the presence of a thermal
inversion caused problems even though calm weather prevailed at the
time of the application. During an aerial application of TEPP (tetra-
ethyl pyrophosphate), a thermal inversion and static air conditions,
as well as topography which impeded the movement of the dust laden
air and the presence of tall crops with dense foliage which constricted
air movement, all combined to prevent the pesticide from dispersing
with the result that persons and livestock near the dusting area were
affected by the pesticide. The conditions of application were those that
had been used successfully for 16 years prior to the date of the acci-
dental poisoning. Therefore, for each individual application, appro-
priate measurements of microclimatology must be made and evaluated
in order to insure that a safe and effective treatment is carried out,
because as this work shows, while it is normally considered desirable
to have little or no wind when spraying pesticides, such weather con-
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ditions may create a problem as serious as that caused by windy
conditions.
Given good micrometeorological renditions, the size of pesticide
particles or drops determines the efficiency of the application, i.e., the
rtctual amount of pesticides which impinges on the target organisms.
If the application efficiency is high, contamination by pesticides caused
by particles which fall on liont argot organisms and/or foliage and
soil, is minimized. If, in addition to more efficient application, pesti-
cides less toxic to nontarget organisms and more selective to target
organisms are used, then a reduction in environmental contamination
will result.
In a study on the spray application for the spruce budworm, Mimel
and Moore (.9) attempted to resolve these problems. They felt that
the spray operation should meet three conditions: (1) An insecticide
which would be more toxic to the spruce bud worm than to other orga-
nisms should be used; (2) the insecticide should be amendable to
breakdown in the forest ecosystem and thus not be accumulated in plant
and animal systems; and (->) the pesticide should be directed to the
target insect with a higher degree of efficiency than to other organisms.
Zcctran, a carbamate insecticide, was selected for use because it
demonstrated a high degree of selectivity for the budworm. It is more
toxic to the budworm than DDT and has a relatively high acute oral
toxicity, which are the main potential hazards in field use. Also, Zec-
tran and its metabolites are readily broken down by sunlight and in
plant and animal systems. The problem of directing the spray to the
spruce budworm with greater efficiency than to any other organism was
then studied.
It has been demonstrated that most forest spraying has been con-
ducted with particles of 150/x mass median diameter, i.e,, 50 percent
of the particles are of drop sizes greater than 150m diameter. This was
true even though earlier work indicated that drop sizes of more than
lOOju, penetrated vegetation only slightly or not at all. Moore made a
study of the drop sizes which would most efficiently penetrate the forest
canopy. Fine fluorescent particles were suspended in the spray. These
particles distributed themselves according to the spray volume in
any given drop. By counting the number of flourescent particles
remaining after a given drop had evaporated, it was possible to
determine the approximate original size of that drop.
When the size and number of spray drops impinging on each spruce
budworm larvae was studied, it was found that no significant number
of drops larger than lOOp diameter and only a small number of drop-
lets between 50 and 100^ diameter reached the target insects. Only
drops below 50ju diameter reached the budworm larvae with any
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371-074 O—169 U
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degree of efficiency. This is significant when it is considered that 95
percent of the spray volume of spray systems normally used in forest
insect control are larger than 50/x diameter. Thus, a great proportion
of this spray fails to reach the target insect and becomes a major
source of environmental contamination. This study resulted in the
development of a spray system which eliminated all drops above 120p
diameter.
Potential exposure hazards.—Pesticides vary in their toxicity to
humans. The potential exposure of a person to a given pesticide often
is determined by the formulation and particle size of the material.
Thus, a compound which may not be considered toxic to humans but
that has been formulated in a way which promotes easy entry into the
body, may be potentially more harmful than a more toxic pesticide
with a more difficult entry path. Particle size is an important factor.
The three main modes of entry of pesticides into the body are by:
(I) inhalation; (2) skin absorption; and (3) ingestion. Hayes (10)
has rated the three major pesticide formulations (gases, dust, and
sprays) according to their potential for entry by the above routes. For
respiratory intake, the most hazardous formulation is a gas. Next are
dusts and the least dangerous are sprays. Thus, the danger from this
route of entry decreases with increasing particle size. The maximum
danger due to skin absorbtion is from sprays and liquids, with dust
posing the lowest threat. Hayes noted that some gasses can pass
through the skin.
The effect of particle size on exposure was studied by Wolfe et al.
(II). The dermal and respiratory exposures to parathion of workers
using both conventional dilute spray machines and low-volume con-
centrate sprays were compared. The particle size of the concentrate
spray is smaller (20 p to 100 /i diameter) than that of the conventional
spray machine (over 150 n diameter). The potential dermal and
respiratory exposures associated with the two spraying methods were
found to be as follows:
Concentrate spraying Conventional dilute
technique spraying method
Dermal exposure 27.9 mg./hr 19.4 mg./hr.
Respiratory exposure 0.055 mg./hr— 0.02 mg./hr.
Most of the difference in the dermal exposure was attributed to a
greater hand exposure with the concentrate machine. The difference in
respiratory exposure was considered to be caused by the smaller drop
size produced by the concentrate spraying method.
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The potential danger of pesticides to handlers and operators is well
known. The literature is replete with accidents which have occurred
with adverse, sometimes lethal, consequences. There is less information
available, however, concerning the pesticide exposure to the general
population. Such information is vital if the proper assessment of the
risk to the general population is to be determined.
Risebrough et al. (12) measured the concentration of pesticides over
Barbados, ail area remote from the agricultural use of pesticides, and
found that the total amount of pesticides in the air ranged from less
than 13X10-° nanograms per cubic meter of air to 880X 1(H ng/m?.
By contrast, the air at La .Folia, Calif., an area adjacent to agricultural
areas where pesticides are used, contained an average of 7.0 X10 2
ng/mz. Thus, the authors concluded that pesticides are universally
present in air and that their distribution from application sites is
dependent on the prevailing patterns of wind circulation and the rates
of fallout.
In 1965, the occurrence of a dust storm of unusual intensity allowed
a study of the transport of pesticides over long distances and the subse-
quent precipitation to earth by rainfall to be conducted {13). The dust
storms were spawned on January 25 in the southern high plain's of
Texas. The dust-bearing air mass gradually moved eastward, spreading
out in a north-south direction and narrowing in an east-west direction
due to airflow patterns within the air mass, and by January 26, parts of
the dust had reached Cincinnati, Ohio. Dust was collected in Cincin-
nati and analyzed for its pesticide content. The major pesticide com-
ponents of the dust were DDT and chlordane with concentrations of
0,6 and 0.5 p.p.m. respectively based on the air-dried weight of the
dust. DDE and Ronnel followed closely in concentration. These four
pesticides, together with three other pesticides, heptachlor epoxide,
2,4,5-T and dieldrin, which occurred in lesser amounts, made up the
major portion of the pesticide content of the dust.
This study gives evidence that pesticides may be transported over
long distances when attached to dust particles in the air. These parti-
cles may be washed out of the air by rainfall and deposited on the
ground. Evidence is also provided that the pesticides can survive
degradation by photochemical reactions in the atmosphere and can be
deposited over land surfaces remote from their point of application.
A study was carried out by Stanley (74) with the express purpose
of determining the atmospheric contamination by pesticides in the
United States. Sampling sites were established at nine locations: Bal-
timore, Md., Buffalo, N.Y,, Dothan, Ala., Fresno, Calif., Iowa City,
Iowa, Orlando, Fla,, Riverside, Calif., Salt Lake City, Utah, and
Stoneville, Miss. Both urban and rural sampling sites were chosen.
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Chlorinated, hydrocarbons such as DDT, BHC, DDE, lindane, diel-
drin, and aldrin, and organophosphorus pesticides such as parathion
and malathion were sought. Only DDT was found at all localities.
The DDT concentrations were highest in the agricultural areas of the
South, Pesticides were found from the lowest level of detection (0.1
ng/m3 air) to as high as 1560 ng/m3 p-p' DDT, 2520 ng/m? toxaphene
and 465 ng/m? parathion.
The highest pesticide levels were found when spraying was re-
ported to have occurred just prior to the sampling. There was no cor-
relation between pesticide levels and rainfall. In most cases, when the
pesticide levels decreased after a rainfall had been reported, it was
also noted that spraying activities had also ceased because of the rain.
The decrease in pesticide levels oould therefore have been due to the
cessation in spraying operations.
The kinds and levels of pesticides found varied with the agricul-
tural activity in a given area. The pesticide levels varied from season
to season according to the chemicals used and crops grown during
each season. Most pesticides were present in the atmosphere as par-
ticulates. There was little correlation between the pesticide level and
the time of day. These concentrations, even the highest levels meas-
ured, are below those encountered by the general population from
other sources. For example, Durham et al. {15) analyzed 12 restaurant
and 17 household meals and found that, based on the food in the meals
analyzed, the mean daily intake of DDT was 1.99 X 10 l ing. If a per-
son inhales 7000 l./day of air containing 1560 ng/m? DDT, he will
inhale 1,092 X10'2 mg/day.
It is obvious from this study that broader sampling programs must
be undertaken in order to establish the pesticide levels to which the
general population is exposed. In the study just mentioned, both urban
and rural sampling sites were chosen, but in different localities. It
might be more meaningful to take both urban and rural samples at
the same locality rather than to try to compare pesticide levels of
rural Mississippi with urban California or New York. In order
to study the pesticide levels in the United States, perhaps one section
of the country should be concentrated on at a time. An area in which
a large amount of pesticides is being used, for example the South-
east, could be selected for study. Within this area, urban and rural
samples would be collected in order to establish the amounts of pes-
ticides transported from the rural spraying areas to the urban center.
In this way, urban exposure could be related to the spraying activities
in the surrounding rural area.
Persistence of pesticides in air.—The presence of pesticides in air
is a function of their chemical nature, physical state, method of ap-
plication, and atmospheric conditions. The persistence of pesticides in
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the air—i.e., the length of time the particles remain in the air—is also
a function of these factors. Pesticides may be lost from the air by sev-
eral means. Gravitational fallout and washout by rain are perhaps the
two major factors which cause pesticide removal from the air. Ex-
posure of pesticides in air to sunlight and reactive compounds results
in degradation or modification of the compounds by photolysis and
catalysis, but the amount of pesticides removed from the air by these
processes is unknown.
The persistence of pesticides in the air is also a function of their
volatility, particularly with spray operations. Spray particles decrease
in size as they fall, due to evaporation and codistillation. If they evapo-
rate completely before they fall to the ground, dust particles remain
and are more liable to drift.
CITED REFERENCES
(/) Middleton, J. T.: The presence, persistence, and removal of pesticides in
air. In Chichester, C. O. (Ed.) : Research in Pesticides. New York, Aca-
demic, 1965, pp. 101-197.
U) Isleb, D. A.: Atomization of low-volume malathion aerial spray. J. Econ.
Entomol. 59:6S8-691, 1966.
(J) Akesson, X. B., and Yates, W. E.: Problems relating to application of ag-
ricultural chemicals and resulting drift residues. Annual Rev. Entomol.
9:285-318, 1964.
(Jf ) Wassebmax, M. Ii.iescu, S., Mandric, G., and Horvath, P.: Toxic hazards
during DDT-and BHC-spraying of forests against Lymantria Monacha.
A. M. A. A rc. In
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(1$) Stanley, C. W.: Study to determine the atmospheric contamination by
pesticides. Final Report Midwest Research Institute, 1968, 99 pp.
(15) Durham, W. F., Armstrong, J. F., and Quinby, G. E.: DOT and DDE
content of complete prepared meals. Arch. Envir. Health 11:641-647, 1965.
The Water Route
The introduction of pesticides into the water environment can occur
even before the raindrop comes into contact with a pesticide-treated
surface. Rainwater was collected continuously over a 12-month period
in the British Isles at seven widely distributed sites. At all sites and
throughout the year, rainwater contained alpha-BHC, gamma-BHC,
dieldrin, pp'DDT, pp'DDE, and pp'TDE. The concentrations were
extremely minute, being of the order of parts/1011 or parts/10" (1).
The major pathway of pesticides into the water environment occurs
through direct application to surface waters and surface run off. The
major recipients of surface run off are streams, lakes, and coastal
waters.
Grownd waters.—Some pesticides ultimately find their way into
ground waters, but the contribution of pesticides to a surface water
such as a perennial stream from a ground water source is—like rain-
fall—minute. Many variables are responsible for the small concen-
trations of pesticides usually found in ground waters. These include
the type of pesticide, its solubility, formulation, and mode of appli-
cation, the soil types, climate, season, amount of soil organic matter,
microbiological populations, and yet other factors. Organochlorines,
for example, have been demonstrated to move only short distances in
soils via the leaching process (2). Another study concluded that it was
most unlikely that parathion could contaminate underground water
supplies by leaching, under normal rainfall conditions (3). Russian
workers found that lindane and heptachlor do not contaminate ground
waters when used in quantities encountered in agricultural practice,
but concluded that to avoid the possibility of contamination, these
organochlorines should not be used oftener than once every 2 or 3
years (4). Working with dieldrin, Eye (5) concluded that it cannot be
transported through soils into subsurface waters in significant amounts
by infiltrating water because of the extremely long time—several
hundred years—necessary to transport the dieldrin in solution through
the top 12 inches of soil. However, ground waters must be vigilantly
protected since, once polluted, the contamination can persist for long
periods of time. That they can become polluted is documented in the
Montebello, Calif., and Colorado arsenal incidents, both of which
involved 2,4-D (6).
The Environmental Control Administration's Bureau of Water
Hygiene recently (summer 1969) queried several States about inci-
116
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dents of well water contamination by pesticides. The reply from Illi-
nois, succinctly characterizes the response from all the States: "* * *
To our knowledge we have never had a. public well water supply con-
taminated with pesticides. Through the years we have had several
instances of private wells being contaminated by and large through
accidental spills and back siphonage directly into the well. A typical
example is a well in Adams County where a farmer was making up
a tank of pesticide. He left a power pump in operation while he went
into his farm home for lunch. While he was there the motor stopped
and the total content of the tank was hack siphoned into the well.
We have rarely had an example of a well being contaminated by
underground infiltration. The few instances where we have had such
condition have been the result of the application of termite control
materials in a trench immediately adjacent to a water supply well."
From Wisconsin it is reported that it took several months to remove
the residual taste from the water of wells accidently contaminated
by 2,4-1) during which time cattle would not drink the water. An
analysis of a private well water in Ohio showed 0.0033 mg. of chlor-
dane per liter but no information was available on the. route of entry.
Another well contained 2A—D in a concentration of 0.0155 mg./l,
which gained entry through run-off from an area sprayed by the
State Highway Department.
The Indiana response stated: "We have learned to expect requests
for help in three or four cases of chlordane in wells every spring or
early summer when exterminators treat for termites. The pesticide
normally associated with termite control is chlordane although one
of the labels sent to us this spring included one percent of an extract
of Lindane." One of the property owners whose well was contaminated
during termite extermination reported that his water still tasted of
chlordane a year later.
In connection with the State's Ground Water Quality Control Act
in Michigan, consideration was given "to the possibility of pollution
of the soil or ground water from the mixing and preparation of spray
materials, fertilizers, or chemicals,*' and that a 150-foot isolation
distance is specified between a well and the preparation or storage
area for such chemicals.
Preliminary results from a Hureau of Water Hygiene survey of
private well water supplies in one State indicate that pesticide pollu-
tion of ground waters is more wide-spread than commonly realized,
although the concentrations are very low. At the time of writing
only nine samples had been analyzed, but all nine showed DDT. In
addition, three contained endrin, two contained chlordane, and on©
each contained dieldrin and heptachlor. Although all concentrations
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were less than one microgram per liter, the possibility of concentrations
increasing with time must be considered.
Surface 'runoff.—The 1967 production of pesticides of 1050 x 10° lbs.
if applied continually to the annual U.S. runoff (1.16X10° million
gallons per day) would result in a concentration of 0.3 mg./l(7).
Although this exercise is purely academic (most of the production
is exported and most of that which is used is degraded or tightly
bound to soils) it does point out the extensive use of pesticides by
our society.
Because of the tight binding characteristics of pesticide residues to
soil particles, it is suggested that the general pollution of water by
pesticides occurs through the transport of soil particles to which the
residues are attached (8). Problems of sampling and analysis preclude
the use of systems designed to give continuous read-out of pesticide
concentrations in water. It is a common finding in water analysis that
fish may contain pesticides in excess of Federal tolerances, yet water
samples from the same environment may fail to reveal the presence of
residues at levels of 1 X 10~3 mg./l. (9). It is not surprising, therefore,
that shellfish—known for their accumulating characteristics—have
been proposed as monitors of water quality for pesticides. Laboratory
experiments showed that oysters and other bivalves remove chlori-
nated hydrocarbon pesticides from experimentally contaminated water
and store them in tissues. In clean water, the residues are flushed out at
uniform rates. Using oysters, Butler (10) conducted a 3-year, 170-sta-
tion study of estuaries that demonstrated that pesticide pollution is
primarily the result of agricultural practices in the associated river
basins, and that in specific locations, industrial or municipal wastes
and noxious insect control programs are major sources of pollution.
The Public Health Service Laboratory at Dauphin Island, Ala.,
clearly demonstrated the seasonal variation in pesticides content of
oysters in Mobile Bay. Peak total DDT levels occurred in late winter
and early spring months, coinciding generally with the maximum
fresh water inflows and minimum salinities of the Bay waters (11).
Nicholson (12) notes the close affinity of pesticides to soil particles
and suggests that the soil-loss equation used in guiding conservation
farm planning be applied to the prediction and control of pesticide
pollution associated with rural run off. The affinity may also be a basis
for water pollution control recommendations based on geographic
zones.
Lakes.—Geologically speaking, lakes are usually transitory bodies.
They are born, they live and age, and they die. Their aging process is
termed eutrophication. That man's influence grossly accelerates the
process is well documented; witness Lake Erie. Lakes and oceans are
veritable sinks for man's wastes- But lakes are infinitely more sus-
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ceptible to man's negligence because of their much smaller size. Even
larger lakes, however, are not immune as witness the Lake Michigan
Coho salmon and Lake Erie eutrophication problems. To illustrate the
concentrations of pesticides present in Lake Michigan water, the re-
sults of grab samples taken from the two intakes to the Chicago filtra-
tion plant during April 1969, showed the following:
Concentration—ppm
Pesticide Plant 1 Plant 2
Lindane 0. 020X10 "» 0. 010X10-®
Heptachlor epoxide 0. 049X10 0. 019X10 ~s
Aldrin 0. 019X10-"
DDT 0.058X10-' 0.034X10-'
pp' DDT 0. 122X10"' 0.029X10-=
A limited number of surface samples collected by the Bureau of
Commercial Fisheries, Ann Arbor Biological Laboratory, from Lake
Michigan in 1968 showed the following:
DDT 2.0-2.8 ppmxlO"6
DDD 0.3-0.5 ppmX10-e
DDE 0.8-1.4 ppm x 10"®
Lakes with waters of lesser amounts of dissolved minerals are more
biologically sparse than more eutrophic lakes. An interesting experi-
ment was performed in Oregon wherein two mountain lakes were
treated with the organochlorine toxaphene. One lake was deep and
biologically sparse, the other was shallow and rich in aquatic life.
The deeper lake could not be restocked with trout for 6 years because
of toxic quantities of toxaphene remaining in the water. Trout were
restocked in the shallow lake within one year. Explanations offered
for the slow recovery of the deeper lake include thermal stratification
due to depth, a slow rate of dilution from small tributaries, and
markedly less plant and animal life (13).
An important aspect—perhaps the most important aspect—of
chemodynamics of a lake and which is fundamental to the life of the
lake as well as to the effects of pesticides therein involves the sediment-
water-chemical interchange. These relationships are well suited to
modern systems analysis and mathematical modeling and deserve
increased study.
The possible buildup of pesticides in the bottom sediments of lakes,
with the result that they become, in effect, reservoirs of pesticide resi-
dues, has received little study. If this phenomenon occurs in lakes
which undergo thermal stratification, the pesticides could theoreti-
cally be resuspended with the sediments during the fall overturn and
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present aquatic organisms with additional exposure to higher con-
centrations than would be expected. Such periodic exposure could
lead to an increased biological accumulation in the food chain.
Most of the studies that have described the fate of pesticides intro-
duced into aquatic systems have found that the decrease in water pesti-
cide concentration which occurs with elapsed time after the applica-
tion is accompanied by an increase in the concentrations of pesticide
found in the bottom sediment and/or the organisms. For example,
Bridges et al. (14) applied 0.02 p.p.m. DDT to a farm pond and ob-
served that the surface water concentration decreased from 0.08 p.p.m.
one-half hour after treatment to zero in 4 weeks. The concentration of
DDT in the bottom mud prior to treatment was found to be 0.08 p.p.m.
One-half hour after treatment, DDT concentration in the mud was 0.21
p.p.m., and after 8 weeks the mud contained 0.19 p.p.m. At this
time vegetation samples contained 5.1 p.p.m. DDT. Twelve months
after treatment, the vegetation had returned to pretreatment levels.
Fish accumulated 3 to 4 p.p.m. DDT and its metabolites within 1
month after the treatment. The levels declined to 2 to 3 p.p.m. 15
months later. Cope (15) reports on a study in which 20 p.p.m. DDT
were added to a microcosm system containing water, mud, vegetation,
sunfish and snails. The water concentration decreased to 0.42 p.p.b. in
14 days but the mud concentration had increased to 6 p.p.b. and the
vegetation to 15.6 p.p.m. The fish contained 1.0 p.p.m. DDT after 2
weeks and the snails 160 p.p.b.
Undoubtedly not all pesticides exhibit the same phenomenon. For
example, the water in a pond contaminated by endrin as a result of
aerial spraying of an adjacent field at the rate of 6 oz. of active ingredi-
ent per acre was found to contain 0.04 p.p.m. endrin 4 days after treat-
ment (16). The water concentration declined for 21 days after which
no more endrin was detected in the water. Endrin concentrations in
the mud after 45 days were found to be 0.35 p.p.m. after which time
the endrin disappeared.
Although some pesticides may not exhibit long-term accumulations
in aquatic systems, the possibility exists that reservoirs of pesticides
became available for recycling back into biotic systems. Therefore,
studies on the rates of pesticide interchange across mud-water inter-
faces and between vegetation and water and the magnitudes of the
pesticide levels involved should be conducted.
Estwarine tvaters
Pesticides are a matter of serious concern to the shellfishing and
finfishing industry as well as to sports fishing enthusiasts. Water qual-
ity standards for pesticides as a means of protecting fish resources ap-
pears to be of value for shellfish but the evidence is not so clear for
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game fish. The studies of Mobile Bay oysters by the Public Health
Service (//) demonstrates the ability of shellfish to cleanse them-
selves of pesticides. Butler (17) reported an ability of shellfish to
cleanse themselves of 0.03 to 1.5 p.p.m. of various organochlorines in a
10-20 day period when placed in clean water. A similar ability for
finfish has not yet been demonstrated.
Although estuarine areas wherein oysters are found would appear
highly vulnerable to pesticide contamination, continuing surveillance
demonstrates that the need for standards is not urgent (18). However,
a surveillance program is highly recommended (19).
The importance of estuarine areas as the nursery areas of the world's
marine food production is discussed by Butler (20). He states that
industrial and domestic pollution of many estuaries has already so
degraded the environment that only the most tolerant of organisms
can persist, and that the remaining uncontaminated estuaries are of
major importance. As pristine qualities cannot be restored to degraded
estuarine environments, consideration must be directed toward the
provision of estuarine hatcheries similar to those used for fresh waters.
The inhibition of marine algal photosynthesis by DDT was investi-
gated by Wurster (21). Four algal species, including a diatom from
Long Island Sound, a coccolithophore and a green alga from the
Sargasso Sea and a neritic dinoflagellate, were tested, as well as a
marine phytoplankton community, by exposing them to DDT and
measuring their photosynthesis as indicated by the fixation of C14.
In all cases an increase in the concentration of DDT from 1 p.p.b. to
100 p.p.b. produced a decrease in photosynthesis from the photosyn-
thetic level of unexposed control algae to approximately 10-40 percent
of the control photosynthesis. At a constant 10 p.p.b. DDT, the inhibi-
tion of photosynthesis decreased with increasing cell concentration
due, according to the author, to a decrease in the amount of DDT in
solution per cell. Wurster states that his laboratory experiment demon-
strated that reduced phytoplankton populations in nature might be
caused by DDT. DDT might also encourage blooms of some algal
species after the selective stress of the chemical has produced a decrease
in other, less tolerant, community phytoplankters. Continued increases
of concentration of persistent pesticides in the marine environment
might then have long-term impact on total photosynthetic activity,
perhaps inducing a change in oxygen and carbon dioxide partial pres-
sures in the atmosphere.
Potable water supply
The Public Health Service Advisory Committee on Use of the PHS
Drinking Water Standards recommended limits for select pesticides
(22). These limits were derived for the Advisory Committee by an
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expert group of toxicologists as being safe if ingested over extensive
periods. The limits for four of the pesticides (aldrin, heptachlor,
chlordane, and parathion) were set at even lower values because of
their organoleptic properties. The pesticides and their limiting con-
centrations are:
Pesticide Concentration, mg./l.
Aldrin 0. 017
Chlordane 0.003
DDT 0.042
Dieldrin 0. 017
Endrin 0. 001
Heptachlor 0. 018
Heptachlor epoxide 0. 018
Lindane 0. 056
Methoxychlor 0. 035
Organic phosphates plus carbamates 0.11
Toxaphene 0.005
2,4=D+2,4,5=^+2,4,5= TP 0.1
1 As parathion in chollnesterase inhibition. It may be necessary to resort to
even lower concentrations for some compounds or mixtures.
It should be noted that these criteria have never been officially
adopted by the Public Health Service in their Drinking Water Stand-
ards although the operating program, the Bureau of Water Hygiene,
utilizes the criteria as guidelines.
Water quality criteria related to recreation as used by the Public
Health Service contain no limits for specific pesticides. The need for
their control is emphasized in terms of satisfactory conditions being
preserved through watershed management; viz., evaluation of poten-
tial health hazards through consideration of the toxicity, persistence,
and exposure hazards of any pesticides to be used (23).
Water is a vehicle for transporting wastes and most waste-treatment
plants use biological processes. The effects of pesticides on these bio-
logical stabilization processes are so far not of great importance at
the concentrations usually encountered (24). However, effects can be
disastrous at the high concentrations that might result from spills or
accidents.
The removal of pesticides by standard water treatment processes
has been found to vary with the individual pesticide and the concen-
trations encountered. In general, it is much more difficult to remove the
low levels of pesticides that occur through continuous contamination
from runoff, etc., than to reduce the high levels which result from
direct application and accidents.
Cohen et al. (25) studied the effectiveness of standard water treat-
ment processes for removing rotenone and toxaphene and concluded
that the single most effective treatment was the use of activated carfion.
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Rotenone and toxaphene at concentrations of 100 p.p.b. were reduced
to 3 p.p.b. and 7 p.p.b., respectively, with 5-6.6 p.p.b. carbon. Alum
coagulation failed to remove either pesticide. Chlorine and chlorine
dioxide were ineffective in reducing the concentration of toxaphene but
did oxidize rotenone. The concentrations required, however, were so
high that the residual oxidants had to be removed by dechlorination.
Aly and Faust {20) {27) found that activated carbon was the most
effective method for removing the herbicide 2,4-D from water. At an
initial concentration of 1 p.p.m., 13.6-16.2 p.p.m. carbon was required
to reduce the 2,4-D concentration to 0.1 p.p.m. The authors found that
precipitation with limestone products did not remove 2,4-D from the
water because of the high solubility of calcium and magnesium salts.
Neither oxidation by chlorination or potassium permanganate nor
coagulation with ferrous sulfate and alum at concentrations of 100
p.p.m. removed 2,4-D from water.
The removal of low concentrations of toxaphene and BHC by carbon
adsorption at a municipal water treatment plant was studied by
Nicholson et al. {28). During a 4-year period, the concentrations of
toxaphene in untreated water was measured at 7 to 270X10 ® p.p.m.
while the concentration of toxaphene in treated water during the same
period ranged from 5 to 410 X10-8 p.p.m. The concentrations of BHC
ranged from 7 to 1,004 X10-6 p.p.m. in untreated water and from 9 to
640 X 10_c p.p.m. in treated water. It was concluded that the treatment
process used was ineffective in removing the low concentrations of
toxaphene and BHC.
The use of other techniques for the removal of low levels of pesticides
from water has not received extensive study and requires further
evaluation. Such methods involve the use of other adsorptive media,
ion exchange resins, selective membranes and pH adjustment and
require that the chemical characteristics of the specific pesticide that
is to be removed be taken into account.
The available data suggest that periodic occurrences of high pesti-
cide levels in water may be reduced to acceptable concentrations by
water treatment practices and that adsorption by activated carbon
is the most effective such treatment. Low level, long-term contamina-
tion, however, is much more difficult to remove and evidence indicates
that current water treatment methods do not eliminate this possible
source of human exposure.
The Report of the National Technical Advisory Committee to the
Secretary of the Interior {22) on water quality criteria for most
industrial uses does not indicate pesticide contamination to be a major
concern. However, water required for food and kindred products and
for the leather industries is specified to be of drinking water quality.
Pesticides can have detrimental effects on irrigation water quality,
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directly or indirectly. The phenoxy acid herbicides (2,4-D has been
mentioned in the Montebello, Calif., and Colorado arsenal incidents)
are suspected contaminants of irrigation water. Brans (29) found that
when 2,4-D at 6 lbs. per acre in irrigation water was applied to red
Mexican beans in the seedling stage, the root systems were severely
damaged and the yield was reduced by 40 percent. When applications
at the same level were made at the bloom stage, the loss rate dropped
to 29 percent.
Tentative guidelines have been suggested for certain herbicides and
for specific crops (22). An example is provided by:
Concentration
Herbicide Type of application Heference crop mg./l.1
Acrolein Furrow
Sprinkler
beans 60
corn 60
cotton 80
soy beans 20
sugar beets 60
corn 60
soy beans 15
sugar beets 15
' Crop injury threshold in irrigation waters.
For most pesticides, however, too little is known about their ultimate
fate and their influence on irrigated agriculture. However, tihus far
evidence does not indicate that under normal use insecticide contami-
nation of irrigation water is detrimental to plant growth or accumu-
lates in or on irrigated plants to toxic concentrations.
Pesticide-laden irrigation waters may be a source of contamination
to nearby streams as a result of flooding and/or runoff. Miller et al.
(30) observed the movement of parathion from cranberry bogs treated
at the rate of 1 lb. per acre into a nearby irrigation ditch and drainage
canal. A parathion concentration of 30 p.p.b. was found in the drainage
canal, immediately after spraying as a result of water seeping through
the floodgate. After 24 hours, the concentrations had decreased to
3 x 10"3 p.p.m. At this time 2,4-D was also detected 50 and 150 yards
down the drainage canal indicating movement of the pesticide from the
point of application. The use of a water tight floodgate would mini-
mize seepage but the overflow of the bog and irrigation ditch as a result
of a heavy rain would remain as a potential source of contamination
of waters and soils in nontargefc areas.
In* a study of the fate of aldrin in rice paddies, it was found that
2 days after seeding with treated seeds at an application rate of 6 oz.
per acre,,the water in the paddy contained 1.6 p.p.b. aldrin plus deil-
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drin (31). After the third and last drainage of the paddy, 14 weeks
after seeding, the water contained 0.07 p.p.b. aldrin plus dieldrin. Up
to 0.027 p.p.b. aldrin plus dieldrin was found in the ditches into which
the paddies were drained after 14 weeks and the small stream which
received this water contained up to 0.44 p.p.b. The river into which
the stream flowed contained as much as 0.023 p.p.b. aldrin plus diel-
drin. Concentrations in the river decreased to below 0.006 p.p.b. after
several more weeks.
In the same study, 7 days after the treatment of a cotton field with
0.4 lb. per acre of endrin, a concentration of 0.66 p.p.b. endrin was
found in the runoff following a 1.15-inch rain. Used irrigation water
contained 0.11 p.p.b. endrin 3 days after spraying. Prior to irrigation,
the water had contained 0.08 p.p.b. endrin. These data indicate that
irrigation water applied to fields following the application of pesti-
cides may be contaminated after use. The degree of contamination
depends on the time interval between the pesticide application and
the irrigation water use, as the water concentrations decrease with
elapsed time. The concentrations of pesticide in runoff after heavy
rains, following pesticide application may be significant, Godsil and
Johnson (S£) studied the pesticides in water used to irrigate the areas
surrounding the Tule Lake and Lower Klamath Lake Wildlife
Refuges located in northern California. Approximately 156,000 acres
of land lie upstream from these lakes and extensive use of pesticides is
made in the area. Water is used and reused throughout the irrigation
system and samples were taken at a point where the water had been
recycled an estimated 5.2 times. Endrin, because of its abundant usage
in the area as well as its high degree of persistence, was found in the
irrigation water in greater amounts than any other chemical. The con-
centrations of endrin in the irrigation water increased during the
growing seasons and decreased to the limits of sensitivity between
seasons. The endrin concentrations of submerged plants, clams and fish
followed a similar pattern. A maximum of 0.10 p.p.b. endrin in the
water and 198 p.p.b. in tui ehubs was found during one growing season.
Thus, the pesticide concentration of irrigation water and aquatic biota
were directly associated with the agricultural activities in the area.
Between growing seasons, both the water and the organisms returned
to low levels of contamination. No mortalities were observed as a result
cf -this contamination. Although these results indicate that short-term
pesticide contamination does not result in a permanent residual con-
centration of pesticides in aquatic organisms, the possible long-term
hazards may onty be postulated.
Direct xpraying.—Pesticides are applied directly to waters for the
control of mosquitoes, obnoxious or undesirable weeds, and snails. In
order to minimize the potential harm of such applications, both to non-
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target biota and to human consumers of water, an analysis of the pro-
posed pesticide's characteristics with respect to uses of the target area
must be conducted prior to its application. An example of a successful
large-scale direct application of a pesticide to waiter which serves both
as a recreational facility and as a water supply is provided by Smith
and Isom (33) who describe the application of 2,4-D for the control
of Eurasian watermilfoil growth in TVA reservoirs. Very stringent
controls were required in order to preserve the aquatic components
of the system as well as to minimize the contamination of drinking
water taken from the impoundments.
Eight hundred and eighty-eight tons of a 20 percent 2,4-D butoxy
ethanol ester granular herbicide were applied to 8,000 acres in seven
reservoirs at rates varying from 40 to 100 pounds of 2,4-D acid equiva-
lent per acre. Prior to the application, laboratory experiments deter-
mined that concentrations of 2,4-D much in excess of the concentra-
tions that would be encountered in the field, were not completely toxic
to mosquito larvae. This indicated that the aquatic fauna would not be
adversely affected by the concentrations resulting from the application.
Following the application of 2,4-D, raw water samples were ana-
lyzed by activated carbon absorption at nine water treatment plants.
At eight of the plants, concentrations in the raw water of less than
1 p.p.b. 2,4-D were found, and at the ninth, 1 to 2 p.p.b. were detected.
Treated water from the ninth treatment plant contained less than 1
p.p.b. 2,4-D. Significant mud concentrations were observed following
treatment, however, and these residues remained high for a consider-
able period of time. In the Watts Bar Reservoir, for example, 58.8
p.p.m. 2,4-D butoxy ethanol ester was found 10 months after treatment.
In the reservoirs examined, no significant change was observed be-
tween pre- and post-treatment numbers of burrowing mayflies, indicat-
ing that the benthic invertebrate populations had not been harmed.
The elimination of the watermilfoil did, however, result in a significant
loss of aquatic insects which utilized submerged vegetation as a habitat.
Although little uptake of 2,4-D by fish was observed, instances of the
accumulation of the herbicide by freshwater mussels were observed.
The large-scale application of a herbicide for the control of nuisance
aquatic plant growth with a minimum of harm to the aquatic eco-
system is demonstrated by this study. The results could not have been
obtained had not the herbicide used been carefully selected.
In another investigation, preliminary studies failed to reveal all
the hazards involved with the proposed direct application of a pesti-
cide to a lake for the control of a nuisance organism. The insecticide
DDD was applied directly to Clear Lake in California for gnat control
in 1949,1954, and 1957 by pouring a liquid concentrate of DDD from
barges (34). The resulting water concentrations were estimated to be
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14 p.p.b. in 1949, and 20 p.p.b. in 1954 and 1957. It was determined
before the applications that DDI) at these concentrations was not
toxic to fish and other aquatic organisms. Dead western grebes, how-
ever, were found in 1954,1955, and 1957 in areas surrounding the lake.
An analysis of the fatty tissue of the birds which died in 1957 indi-
cated that DDD was present at a concentration of 1600 p.p.m. Sub-
sequent DDD analyses were made on members of the fish populations
and it was found that all fish contained DDD, and that carnivorous
fish contained more than plankton-feeding fish. It was concluded
from this study that the grebe losses, occurring after the DDD appli-
cations, were caused by chronic DDD poisoning resulting from eating
DDD-contaminated fish. Therefore, studies prior to the application,
which indicated that the DDD concentrations used were not toxic on
a short-term basis, did not take into account the biological concen-
tration of the pesticide through the food chain.
Mosquito control.—Current mosquito control practices utilize both
larvacide and adulticide techniques. The Southern operations—includ-
ing the States of Alabama, Florida, Georgia, Louisiana, Mississippi,
South Carolina, and Texas—rely on light oils applied with spreading
agents in their larvaciding operations. Aircraft application is used
for large areas at the rate of 5 gallons per acre. Paris green pellets are
also applied by some districts, and, again, sometimes the aerial route
is used. Resistance is the primary reason that organochlorines and
organophosphates are not used.
The Southern operations also rely extensively upon engineering and
drainage techniques. These are not too amenable to Western activities,
however, where irrigation is a prime cause of mosquito burdens.
These areas have also met with extensive resistance problems and
have gone through chemicals such as DDT and Abate. Last year,
Dursban was utilized in large-scale tests because it appeared that this
chemical would be a more economical choice than oils or Paris green
pellets.
Adulticiding operations utilize ground equipment such as the new
Leco ULV (ultra-low-volume) and chemicals such as malathion and
Naled. Aircraft—fixed-wing and helicopters—have been used to apply
Baytex, and organophosphate. ULV and fogging operations are often
conducted in populated areas.
Mwnicipal and industrial waste discharges,—As with many other
industrial processes, the wastes of the pesticide manufacturing and
formulating industries usually may not safely be introduced directly
into receiving bodies of water. The treatment required to reduce tho
toxicity of the wastes to levels which will not endanger aquatic sys-
tems varies with the components of the wastes themselves. Some com-
pounds are amenable to treatment by chemical and biological processes
127
371-074 O—
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while others are more resistant to conventional treatment. Settling
basins are often used to allow time for waste decomposition and for
impoundment during periods of low flow. Solid and heavy liquid
wastes may be incinerated effectively, often in combination with the
scrubbing of effluent stack gasses for removal of harmful vapors.
Adequate incinerator operation is essential. The deep well disposal of
wastes may be practical in some instances but, because of the risks in-
herent in this disposal technique, a thorough evaluation of the geologi-
cal characteristics of the area and the nature of the waste involved is
required in each specific instance before this method is employed.
Water concentrations.—As part of the National Water Monitoring
Network, samples of a water-suspended sediment mixture from 11
streams in the Western part of the United States were analyzed
monthly for 12 different pesticides beginning in October 1965 (35).
The compounds for which analyses were made included aldrin, DDD,
DDE, DDT, dieldrin, endrin, heptaclilor, heptachlor epoxide lindane,
2,4-D, 2,4,5-T and silvex. All insecticides were found at one time or
another but not at all stations. The amounts observed were small,
ranging from less than p.p.t. (parts per trillion) lindane, to 110 p.p.t.
DDT. Insecticide concentrations of 5 p.p.t. or more were found in
slightly more than 50 percent of all positive samples. No herbicide was
found at any time at any station.
Although no definite seasonal pattern could be noted in pesticide oc-
currence, positive results were more frequently found in February,
March, April, and May, Lindane was the most frequently found in-
secticide and occurred in 46 of the total 165 positive results. The most
infrequently occurring pesticide was aldrin which was observed only
four times at all stations. The most frequent occurrence of pesticides
was at the Rio Grande River station below Anzalduas Dam, Tex.,
where 20 percent of the total positive results were observed. The least
number of positive results was observed at the Snake and Columbia
River stations each of which recorded only seven pesticide occurrences.
Since the amounts of pesticide applied in the various areas could not be
ascertained, no relationship could be made between residues in the
water and the agricultural use of pesticides.
Studies of the chlorinated hydrocarbon pesticide content of sedi-
ments in water from the lower Mississippi River and its tributaries
were conducted in 1964, 1966, and 1967 to determine the extent of
possible sources of agricultural pesticides in the streams of the Delta
(36). There were two areas of significant pesticide contamination, one
in Memphis, Tenn., and the other in Mississippi. Both were in associa-
tion with chlorinated hydrocarbon pesticide manufacturing plants.
Pesticide residues were detected from both agricultural and nonagri-
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cultural areas. There was, however, 110 evidence of a general build up
of chlorinated hydrocarbons in the sediments of these streams from the
agricultural use of pesticides. DDT analogs and associated metabo-
lites were found in some of the tributary streams where no known for-
mulators were located. These data indicate that the large amount of
chlorinated hydrocarbon pesticides applied to crops in the Mississippi
River Delta have not created widespread contamination of the water
and sediments in the area.
As a part of a nationwide program to determine the levels of cholori-
nated hydrocarbon pesticides in estuaries, nine California estuaries
were sampled during 1966 and 1967 (-57). Shellfish were used as sam-
pling organisms because of their ability to concentrate low pesticide
levels in the marine environment. Among the pesticides found were
lindane, heptachlor, aldrin, heptachlor epoxide, DDT, dieldrin, and
endrin. Based on the wet weight of homogenized oyster, mussel, and
clam tissue, DDT, DDD, DDE, dieldrin, and endrin were found in
estuaries in concentrations from 10 to 3,600 p.p.b. High levels of DDT,
DDD, DDE were observed from offshore exposure, as the king crab
contained 2,739 p.p.b., and the ova from a cape salmon 668 p.p.b. The
pesticide levels of shellfish in estuaries receiving runoff from agricul-
tural and urban areas were found to be as high as 11,000 p.p.b. The
pesticide residues in estuaries geographically isolated from agricultural
areas seldom exceeded 100 p.p.b.
From 1958 to 1965, samples taken at more than 100 stations in the
major river basins of the United States were analyzed by carbon
adsorption for their chlorinated hydrocarbon content (38). Dieldrin,
endrin, and DDT concentrations as high as 0.100 p.p.b., 0.116 p,p.b., and
0.148 p.p.b., respectively, were found at various sampling stations.
The results of this study indicate that the most widely found chlori-
nated hydrocarbon pesticide was dieldrin which occurred most fre-
quently in all river basins. Endrin was found occassionally in the early
years of the survey with increases in incidence occurring in 1962 and
1963. The maximum frequency of occurrence of endrin was found in
1964, particularly in the lower Mississippi River, after which endrin
levels decreased. DDT and its associated compounds were found regu-
larly from the beginning of the study with a slightly increasing trend
in evidence.
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The persistence of toxaphene in lake water and its uptake by aquatic
plants and animals. J. Agr. Food Chem. 14 : 66-69,1966.
(14) Bridges, W. R., Kallman, B. J., and Andrews, A. K.: Persistence of DDT
and its metabolites in a farm pond. Tram. Am. Fish Soc. 92: 421-427,
1963.
(15) Cope, O.B.: Agricultural chemicals and fresh-water ecological systems.
In Chichester, C. O. (Ed.) : Research in Pesticides New York, Academic,
1965, pp. 115-127.
(16) Bridges, W. R.: Disappearance of endrin from fish and other materials of
a pond environment. Trans. Am. Fish Soc. 90: 332-334,1961.
(17) Butler, P. A.: Pesticides in the environment and their effects on wildlife.
J. Applied Ecology 3 (Suppl.) : 253-259,1966.
(18) Hammerston, R. J., Russell, R. T., Tyo, R. M., Robertson, E. A., Jr.,
Gaines, J. L. and Bugg, J C„ Jr. : Study of Pesticides in Shellfish and
Estuarine Areas of Louisana. U.S. Dept. Health, Education, and Welfare,
Public Health Service, Cincinnati, Ohio, 1967, 26 pp.
(19) Mason, J, W. and Rowe, D. R.: Dieldrin and Endrin .Concentrations in
Oysters. Dept. Civil Engineering, Tulane Univ. (undated).
(20) Butler, P. A.: The problem of jjestlcides in estuaries. Amer. Fish Soc. Sp.
Pub. No. 3.1966, pp. 110-115.
(21) Wurster, S. F., Jr.: "DDT reduces photosynthesis by marine phytoplank-
ton." Science 159:1474-1475 (1968).
(22) U.S. Department of the Interior : Water Quality Criteria. Reports of the
National Technical Advisory Committee to the Secretary off the Interior.
Federal Water Pollution Control Administration, Washington, D.C.,
1968, 234 pp.
130
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(S3) U.S. Department of Health, Education, and Welfare : Health Guidelines
for Water Resource and Related Land Use Management, Bureau of
Water Hygiene, Environmental Control Administration, Rockville, Md.,
II-8, 1968.
(24) Gxjyeb, G. E., Barclach, J. A., and Kenaga, E. E.: Report of the Governors
Pesticide Advisory Panel, 1968. Michigan, 1968,13 pp.
(2o) Cohen, J. M., Pickering, Q. H., Woodward, R. L., and Van Heuvelen, W.:
Effect of fish poisons on water supplies. Part 3. Field study at Dickinson.
J. Am. Water Works Assoc. 53; 233-246,1961.
(26) Aly, O. M. and Faust, S. D.: Studies on the removal of 2,4-D and 2,4-DCP
from surface waters. Proc. 18th Ind, Waste Cont. 115: 6-8,1964.
(37) Faust, S. D. and Aly, O. M.: Water pollution by organic pesticides. J.
Am. Water Works Assoc. 56 : 267-275), 1964.
(28) Nicholbon, H. P., Grzenda, A. R., Lauer, G. J., Cox, W. S., and Teasley,
J. I.: Water pollution by insecticides in an agricultural river basin. I.
Occurrence of Insecticides in river and treated municipal water. Lint-
nol. and Oceanog. 9: 310-317,1964.
(29) Beuns, V. F.: The response of certain crops to 2,4-dichlorophenoxyacetlc
acid In irrigation water. Weeds 1: 359-376,1951.
(30) Miller, C. W., Tomlinbon, W. E., and Nobgen, R. L.: Persistence and
movement of parathion in Irrigation waters. Pest. Mon. J. 1: 47-48, 1967.
(31) Spabr, B. I., Appleby, W. G., DeVries, D. M., Osmon, J, V., McBride, J. M.,
and Foster, G. L.: Insecticide residues in waterways from agricultural
use. In Gould, R. F. (ed.) : Organic Pesticides in, the Environment. Wash-
ington, D.C., Advances In Chemistry Series, American "Chemical Society,
1966, pp. 146-102.
(82) Godsil, P. J. and Johnson, W. C.: Pesticide monitoring of the aquatic
biota at the Tule Lake National Wildlife Refuge. Pest. Man. J. 1; 21-26,
1968.
(33) Smith, G. E. and Isom, G. G.: Investigation of effects of large-scale ap-
plications of 2,4-D on aquatic fauna and water quality. Pest. Mon. J.
1: 16-21, 1967.
(34) Hunt, E. G. and Bischoff, A. I.: Inimical effects on wildlife of periodic
DDD applications to Clear Lake, Cal. Fish and Game 46 : 91-106, 1960.
(35) Brown, E. and Nishioka, Y. A.: Pesticides in selected western streams.
A contribution to the national program. Pest. Mon. J. 1:38-46, 1967.
(36) Babthel, W. F., Hawthorne, J. C.t Ford, J. H., Bolton, G. C,, McDowell,
L. L., Gbissingxr, E. H., and Parsons, D. A.: Pesticide residues In sedi-
ments of the lower Mississippi River and its tributaries. Pest. Mon. J.
3 : 8-66, 1909.
(37) Modin, J, C.: Chlorinated hydrocarbon pesticides In California bays and
estuaries. Pest. Mon. J. 3:1-7,1960.
(38) Bbeidenbach, A. W.. Gunnehson, C. G., Kawaha&a, F. K., Lichtknberg,
J. J., and Gbeen, R. S.: Chlorinated hydrocarbon pesticides in major
river basins, 1957-65, Pub. Health Repts. 82:139-156,1967.
The Food Route
CROP APPLICATION
There is a tendency toward the overuse of pesticides both in agri-
cultural as well as in domestic activities. In large-scale operations the
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dusting or spraying operation is frequently conducted with the avowed
purpose of serving as a prevention of blight or insect infestation in
order to assure against potential loss. In some cases an assessment of
the actual existing infestation or evidence to indicate the exact dosage
required would lead to considerably smaller amounts of pesticides
l>eing used.
Excessive household use of pesticides occurs because of the complete
lack of a scientific approach to their employment. In cases where large
scale applications are made by plane, commercial spraying or fogging
equipment, attention must be given to problems of drift associated
with wind and air currents. Depending upon the degree of infestation
and the nature of the meteorological conditions, occasions have arisen
where the felt need for pesticide application did not allow the post-
ponement of the spraying operation until more favorable meteorolog-
ical conditions existed. In such cases, drift has been experienced to a
distance as great as 100 miles.
Systemic versus surface-type pesticides.—Some research has been
conducted on plant systemic pesticides which allow the pesticide to be
picked up by the roots of the plant and carried through the plant
system. To date, while some applications of this type have been suc-
cessful, the overall prospects for wide-scale adoption do not appear
to be very promising. In addition to the potential of reducing the
waste of the more conventional types of application such an approach
would increase contamination of the soil. Questions have also been
raised in regard to the use of plant systemic pesticides in relation to
the possibility of the contamination of the fruit and plant which
are subsequently used for human or animal feed.
Pesticides from soil to plants.—Crops may absorb pesticides from
soil previously treated. In areas where short-term crops are raised,
such as in truck farming where the crops have relatively short grow-
ing periods and where repeated applications of pesticides may be used
for each crop, there is evidence that a considerable amount of pesti-
cide residue remains in the soil and is picked up by the plant and
deposited in varying amounts in the food product.
For example, Lichtenstein et aI, (1) found that cucumbers grown
on soil treated once a year for 5 years with aldrin, dieldrin, and hep-
tachlor at the rate of 5 pounds per inch-acre contained up to 0.011,
0.102, and 0.23 p.p.m., respectively. Similar residues were found in
both the upper and lower halves of the cucumbers. The pesticide
residues had penetrated the root system and were translocated to the
fruit. In the same study, it was found that alfalfa grown on soil con-
taining 0.5 p.p.m. per inch-acre of aldrin or heptachlor would contain
approximately 0.005 p.p.m. of aldrin and dieldrin or 0.015 p.p.m. of
132
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heptachlor and heptachlor epoxide. Similarly, Wood et aJ. (&) found
that alfalfa grown on fields treated 4 and 5 years earlier with dieldrin
at 5 pounds/acre contained as much as 0.03-0.04 p.p.m. dieldrin. The
residues of corn grown on the same fields did not differ greatly from
those of the alfalfa,
Bruce et al. (3) studied the relationship between the pesticide resi-
dues in several crop seeds, the soil concentration and fat content of
the seeds. Their results are as follows:
Seed
Soil residue
p.p.m.
Seed residue
p.p.m.
Heptachlor and heptachlor epoxide.
Corn -
0. 5-4.
0
0. 002-0. 01
Barley
0. 5-4.
0
0. 002-0. 02
Oats
0. 5-4.
0
0. 008-0. 08
Aldrin and dieldrin
Corn
0. 35-3.
5
0. 002-0. 008
Barley __
0. 35-3.
5
0. 006-0. 015
Oats
0. 35-3.
5
0. 007-0. 08
Seeds with high fat content such as soybeans and peanuts contained
greater pesticide residues than did seeds of lower fat content.
Nash (4) grew wheat in soils treated with DDT and dieldrin at
0.5,2 and 10 p.p.m. Dieldrin residues in the wheat seedlings increased
in direct proportion to the soil application rate. DDT residues also
occurred in the seedlings but to a lesser extent. After 3 weeks, dieldrin
seedling residues were approximately 18 percent of the soil concen-
tration and DDT residues approximately 3 to 10 percent. The transfer
of pesticides contained in a soil to crops via the root system can there-
fore be a significant source of food contamination.
Metabolism of pesticides by the plant.—Studies of the ability of
plants to metabolize pesticides which have been applied either to the
surface of the plants or which may be found in the soil have indicated
that in some cases this process can serve as a means of reducing the per-
sistence of the pesticides. For example, the destructive hydrolysis of
organophosphate insecticides on plant surfaces and within plant
cells (especially for systemic insecticides) allow such strong pesti-
cides as TEPP, Phosdrin and Mevinphos to be used safely on edible
fruits and vegetables within a day or two of harvest. Persistent chlo-
rinated hydrocarbon insecticides, on the other hand, do not undergo
degradative reactions in such short time periods.
In other cases, however, more harmful and/or persistent compounds
may be reduced by metabolic processes. It is well known that within
plant cells aldrin may be converted to epoxide dieldrin and hepta-
chlor to heptachlor epoxide. The vapor pressure of the epoxide com-
pounds are lower than that of the parent chemicals with the result
133
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that the half-life values of the pesticides increase from about 1 day to
7-8 days.
The effect of plant characteristics on residue.—A number of plant
characteristics require additional application of pesticides at various
stages of production. These include growth rate of the plant, foliage
density, shape of the plant, surface characteristics of the leaves, stems
and brandies, problems of the enzyme systems of the plant, and the
metabolic rates of the plant. The amount of residue which actually
conies in contact with the plant and remains effective depends to a
great extent on all of these factors.
Time factor.—The pesticide residue carried to human food may
depend on the period of time between the application of the pesticide
to the crop and the harvest and processing of the crop. The intensity
of the application, growth, dilution, and degradability are coupled
with the time and method of processing. All of these factors must be
considered in the assessment of the amount of pesticide which reaches
the ultimate consumer.
Mann and Chopra (5), for example, found that carbaryl residues on
cabbage and eggplants decreased exponentially from the day of appli-
cation. Their results, after spraying the plants at three different rates
every 3 three weeks for 9 weeks, are as follows:
Initial residues—p.p.m.
0.55 pound/acro
1.1 pound/acro 2.2 pound/acre
Cabbage (0 day)
Cabbage, washed (0 day) _ _ _
Eggplant (1 day)
14. 80
0. 97
8. 33
23. 83 33. 86
1. 34 1. 25
12. 22 16. 86
7-day residues—p.p.in.
0.65 pound/acro
1.1 pound/acro 2.2 pound/acre
Cabbage,
Cabbage, washed
Eggplant _ -
2. 50
1. 44
3. 05
3. 94 5. 13
2. 17 2. 94
4. 31 40
The rate constant was 0.17-0,28 per day for both vegetables and the
half-life values for cabbage and eggplant were 3 and 3.2 days respec-
tively. These results indicate that ample time must be allowed for
pesticide die off before processing, even though carbaryl and other
pesticides do exhibit a rapid residue loss rate. It is therefore important
that the rate of residue loss is known by the farmer and food processor,
in order that pesticide application and crop harvesting and processing
may be coordinated. These results also indicate the process of pesti-
cide dissipation may be speeded up by such procedures as washing.
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The use of the crop.—The route of pesticides to man may depend
upon the use of the crop in question. For fiber products, the residue
on the crop may cause less concern, except in cases of those persistent
pesticides which may cause dermatitis or which are toxic by skin
absorption.
Some food products which are subjected to a series of pesticide
applications are consumed by the public without extensive processing.
In other cases, the processing of the food may remove a portion of the
pesticide residue while in other cases the food processing method may
serve to concentrate and accentuate the pesticide problem in the
food product.
Surveys of food in the markets of the nation indicate varying
amounts of pesticide residues in many commercial foods. The total
dietary exposure varies from one part of the country to the other
and depends upon the dietary habits of the individual or family.
Few, if any, foods are completely free from some degree of pesticide
residue.
The dietary intake for pesticide chemicals in the United States from
June 1966 to April 1968, is reported by Duggan and Lipscomb (
-------
their greater persistence and wide use. The daily intake of chlorinated
hydrocarbons has been relatively consistent since 1964. DDT and its
analogs comprised approximately two-thirds of the chlorinated hydro-
carbon residues found during the 1967 and 1968 periods. DDT alone
accounted for approximately one-fourth of the total intake of chlori-
nated hydrocarbons. The major sources of the chlorinated hydrocar-
bons were those food classes representing products of animal origin,
namely, "dairy products and meat, fish and poultry." These foods were
the source of approximately one-half of the total intake of chlori-
nated hydrocarbon residues. In view of the fact that these products
received little direct application of pesticide chemicals, their presence
must be due to indirect and environmental sources. Grain, fruits,
and garden fruits combined to account for about 40 percent of this class
of pesticides. The dietary intake from the remaining seven food classes
studied: Potatoes; leafy vegetables; legume vegetables; root vege-
tables; oils, fats, and shortening; sugars and adjuncts; and beverages,
accounted for about 10 percent of the chlorinated hydrocarbon
residues.
Dieldrin, lindane and heptachlor followed DDT and its analogs in
magnitude of dietary intake. The incidence and amounts of other
chlorinated hydrocarbons detected in the study were too low to be of
any dietary significance.
Organophosphate insecticides.—Approximately one-third of the
organophosphate insecticides were found in grains and cereals. Mala-
thion accounted for 80 percent of the calculated daily intake of organ-
ophosphates. The average daily intake for this 2-year period was 0.009
mg./day. The incidence and intake of the remaining seven organophos-
phorous insecticides detected were too low to be considered as regular
components of the diet.
Herbicides.—About 50 percent of the herbicide residues detected
during the 1967 and 1968 periods were in foods of animal origin, that
is, dairy products and meat, fish and poultry. This is again idicative
of environmental contamination since herbicides are not used directly
on these products. The two most frequently found herbicides were
2,4-D and PCP.
Carbamate insecticides.—The incidence and amounts of carbamates
were very low in both study periods. The insecticide carbaryl was found
in four composite samples in 1967 but was not found at all in 1968.
For 1967 its calculated daily intake was 0.006 mg./day. This group of
chemicals did not occur at sufficiently high levels of frequencies to be
considered as contributors to the daily intake of pesticide chemicals.
Dithiocarbamate residues were found in a few samples in both study
periods. Evidently this class of insecticide decomposes sufficiently dur-
136
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ing harvesting and processing so that it is not regularly found in
ready-to-eat food.
Inorganic residues.—Inorganic bromides were found in approxi-
mately 80 percent of all samples examined during the 1967 and 1968
periods. Bromide residues were found in all food classes, but the highest
residues were found in the grain and cereal class. The average daily in-
take for the 2-year study period was approximately 24 mg.
Arsenic residues were detected in 10 percent of the composite samples
examined in 1967 and in 18 percent of the samples analyzed in 1968.
The daily intake of arsenic, calculated as A8203f was 0.33 mg. for 1967
and 0.137 mg. for 1968.
When the dietary intake of pesticide chemicals is compared with the
acceptable daily intake proposed by the Food and Agricultural Or-
ganization of the United Nations and the World Health Organization
Expert Committee on Pesticide Residues, it is found that no acceptable
daily intake value was exceeded by food residues during the 1965-1968
period. The daily dietary intake for practically all pesticides was at
least one order of magnitude (1/10) or more below that considered
safe by the FAO-WHO reports. The average combined level of aldrin
and dieldrin, however, was approximately equal to the acceptable
daily intake values. This is significant because, except for DDT and its
analogs, dieldrin is the pesticide most frequently found in food. The
following table compares the FAO-WHO acceptable daily intake
values with the dietary intake of several pesticides during the 1965-
1968 period.
FAO-WHO Expended dietary intake1
acceptable
i
laily intake'
1966
I960
1967
1968
Aldrin and dieldrin
0. 0001
0. 00009
0. 00013
0. 00006
0. 00006
Carbaryl
. 02
. 0021
. 0005
. 0001 .
DDT, DDE, TDE
. 01
. 0009
. 0010
. 0008
. 0007
Lindane
. 0125
. 00007
.00006
. 00007
. 00004
Heptachlor and
heptachlor epoxide
.0005
. 000033
. 00005
. 000021
. 000031
Malathion.- _ _ .
.02
. 0001
. 0002
. 00004
Parathion
.005 .
. 00001
. 00001
. 000001
All chlorinated hydro-
carbons
. 0012
. 0016
. 0012
. 0011
All organophosphates
. 00014
. 00025
. 00007
All herbicides
.00012
. 00022
. 00005
. 00006
' (mg/kg. body wt./day).
In summary, the kinds, frequency and levels of chlorinated hydro-
carbon pesticides found in the total diet samples during 1967 and
1968 do not differ significantly from those found from 1964 and 1966.
137
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Chlorinated hydrocarbon residues were commonly found in all diet
samples and in all food classes except beverages. The incidence of
organophosphorus pesticides increased during the 4-year study period.
Malathion was the major contributor of this group to dietary intake.
The incidence and levels of herbicides have remained low throughout
the 4-year study. No herbicide residues were found in legume and
root vegetables and garden fruits. The incidence of carbaryl and
carbamate chemicals were too low for these pesticides to be consid-
ered as regular constituents of the diet.
Foods of animal origin were the main source of chlorinated hydro-
carbon residues in the diet. These foods comprised about one-fourth
of the diet used in the study. These foods were the source of about
one-half of the intake of total chlorinated hydrocarbon residues and
DDT compounds and were the source of even a greater proportion of
heptachlor epoxide, BHC and dieldrin. Since the residue levels of
aldrin and dieldrin are about the same as the acceptable levels of these
compounds, it is possible that the acceptable daily intake may be ex-
ceeded under certain dietary patterns. Reductions in residue levels
in foods of animal intake would be the most effective means of re-
ducing the dietary intake of pesticides, particularly the more toxic
pesticides.
The exposure of the general population, therefore the impact of
pesticides on the health of man, is much greater through the food
route than either air or water. Although "market basket" studies indi-
cate that the exposure of the population to pesticides through food
over the last few years has generally not increased, present levels of
intake, particularly for aldrin and dieldrin, may be some cause for
concern. At any rate, so far as the health of the general population
is concerned, the greatest emphasis in pesticide control should be on
reducing the concentration in foods. Methods for such reduction are
available and are being applied on an increasing scale.
Animal feed.—Market basket surveys indicate that foods of animal
origin contain relatively high levels of pesticide residues. As meat and
dairy products are not directly treated with pesticides, the consumption
of contaminated feed is probably responsible for the subsequent build-
up of pesticides in animal tissues. The wide variety of components such
as fish, soybeans, and cottonseed contained in animal feed increases the
potential contamination of the feed by pesticides.
The length of time that the residues remain at high levels in animal
tissue varies with the pesticide and the concentrations consumed. Often
the tissue residues decrease after the cattle stop eating contaminated
feed. If the cattle were killed and prepared for human consumption
while still eating contaminated feed or immediately after they had
13*
-------
stopped eating such feed, however, significant residue levels in the meat
might be found if they were originally high. The build-up of pesticide
residues in cattle tissue was studied by Rusoff et al (7) who measured
the residues of heptachlor epoxide in the fatty tissue of cattle which
grazed on pasture treated with 0.25 lbs./acre heptachlor. The cattle
were allowed to begin grazing on the field at intervals of 1, 8, 15, 29,
and 43 days following the application of the pesticide. The cattle
which began grazing 1 day after treatment contained 2.5 p.p.m. hep-
tachlor epoxide in the fat. No pesticide was found in the cow which
began grazing 43 days after treatment indicating that the pesticide
level in the forage had declined. The fatty tissue residues decreased
with increased elapsed time before grazing began. Several cows were
allowed to begin grazing on a field during an application of 0.25 lbs./
acre heptachlor. The average fat content in these cows was found to
contain 3.45 p.p.m. heptachlor epoxide after 29-30 days. The concen-
tration decreased with increasing time from the application. Less than
1 p.p.b. heptachlor epoxide residue was found in the raw and cooked
meat of cattle which had grazed for 125 days. This study indicates
that although pesticide residues do build up in tissues as a result of
eating contaminated feed, the residues are reduced after such feeding
is terminated.
Claborn et al(8) found that after feeding toxaphene to cattle
over an 8-week period at rates of 60,100, and 140 p.p.m., fat residues
were 8.4,14.3, and 24.3 p.p.b. respectively. Claborn et al, (5) also found
that no residues of Sevin were found in the tissues of cattle, sheep,
goats, and hogs after they had been sprayed four times in 2 weeks
with a 1 percent suspension. One goat contained Sevin in the fat
of the brain. The tissues of Hereford steers fed 50 and 20 p.p.m. Sevin
for 27 days also contained no residue.
The excretion of pesticides in milk after cattle have consumed for-
age previously treated with pesticides can also be a problem. Cows
fed DDT in their diet at rate of 0.5,1.0, 2.0, 3.0, and 5.0 p.p.m. DDT
in alfalfa exhibited DDT in their milk at all feeding levels except
0.5 p.p,m. (10). At 1 p.p.m., residues of 0.01 to 0.03 p.p.m. were
consistently present in the milk after 19 days. As the DDT feed levels
increased, the DDT contamination in milk increased. At a feeding
rate of 5 p.p.m. DDT, significant DDT levels appeared in the milk
from a Guernsey cow. The milk concentration during the feeding
period ranged from 0.16 to 0.32 p.p.m. Cows were also fed toxaphene
at rates of 2.5, 5,10,15, and 20 p.p.m. for 77 days (11). The milk con-
centrations increased with the amounts in the food. The residue levels
in the milk plateaued after the 28th day except for the 2.5 p.p.m.
level at which a plateau was reached after the 9th day. Plateau levels
199
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in the milk at the 2.5, 5, 10, 15, and 20 p.p.m. toxaphene feeding level
were 0.043, 0.076, 0.100, 0.17ft, and 0.179 p.p.m. respectively. A rapid
decline in pesticide milk residues was observed after the feeding of
toxaplieue was terminated and, 14 days after the termination, almost
all the cows produced milk with non detectable amounts of toxaphene.
Thus it appears that milk residues as well as tissue residues* decrease
after termination of the feeding on contaminated forage. Not all pesti-
cides produce residues in milk. Loeflier et ah. {12) found that Guthion
did not produce detectable residues in milk at feeding levels of 4.2 to
33.3 p.p.m. Guthion metabolites were detected, however, but disap-
peared within 3 days after treatment was discontinued.
The spraying of cattle with insecticides for insect control may pro*
due© milk and tissue residues. Claborn et a?., (5) sprayed cows with
toxaphene and strobane in a 0.5-percent emulsion, a 0.5-percent sus-
pension, and a 2-percent oil spray. These concentrations are entomo-
logically effective. The emulsion and suspension were used twice at 3-
week intervals and the oil spray twice daily for 21 days. The maxi-
mum residues in milk (0.61-0.71 p.p.m.) occurred 1 or 2 days after
the first spraying with the emulsion and suspension and then decreased
to low values at 21 days {0.05-0.12 p.p.m.). There was no significant
difference in residue levels between the two formulations or two insec-
ticides. The residues of both toxaphene and strobane reached the
maximum (0.28-0.41 p.p.m.) about the third day of oil spraying then
remained at approximately the same level for 18 days. Since no resi-
dues are permitted in milk, these insecticides are not recommended
for use in the control of cattle insects. Thus, animals which are fed
on feeds containing pesticide residues or which are sprayed with
pesticide for insect control may serve as an additional source of
pesticides to the consuming public,
Moubry et al., (IS) studied the decline of chlorinated hydrocarbon
pesticides in the milk of cows. After pesticide residues were detected
in the milk of several herds, all efforts were made to remove the cows
from exposure to pesticides by removing the cows from contaminated
food and/or dermal spraying for insect control. After removal from
the pesticide sources the residues eventually declined to a point below
actionable levels. Dieldrin had the longest retention time in milk, ap-
proximately 100 days. DDT and its analogs, BHC, lindane, endrin, and
methoxychlor follow in that order. The amount of DDT, DDD, DDE
residues in milk varied in relation to each other depending upon
whether the animal exposure was by ingestion or dermal application.
This knowledge is useful when determining the source of pesticide
exposure.
140
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Direct exposure.—Various foods receive a direct exposure to pesti-
cides during the growing season and, depending upon the methods of
processing, may contribute considerable pesticide to the diet of the
food customer. The problem to the consumer in this situation depends
upon the degradability of the pesticide, the time factor between the
application and the final processing, the time factor in shipping and
the amount of pesticide applied. The degree of penetration of the pesti-
cide into the food material is also of concern with certain types of
food.
Koivistoinen et aH. (14) studied the fate of malathion residues from
post-harvest treatments during food processing of gooseberries, plums,
tomatoes, apples, and stringbeans. The approximate residue reduction
produced by the various processing techniques were: Canning, 50 per-
cent or more; processes with a cooking period of 15 to 20 minutes, 30
to 50 percent; juice making by pressing or steaming, 70 to 90 percent;
drying at 75° C. for 1 to 2 days, 90 to 100 percent; and freezing, 40 to
50 percent. Losses of from 0 to 79 percent were obtained by washing
the fruits in running water for 1 minute. Virtually no malathion was
lost when the processed materials were stored at 4° C. for up to 8
months.
The removal of DDT, malathion, and carbaryl from tomatoes by
commercial and home preparative methods was studied by Farrow
et aL., (15). Commercial canning and juicing operations removed prac-
tically all DDT, malathion, and carbaryl residues. All but trace
amounts of DDT and malathion were removed by the home canning
of whole tomatoes and tomato juice. Approximately 92 percent of the
carbaryl residue was removed by canning whole tomatoes and 77 per-
cent removed by the home canning of tomato juice. Home preparation
removed approximately 85 percent of the DDT residue, 96 percent of
the malathion and 69 percent of the carbaryl residue. Raw, unwashed
fruit stored at 55° F. exhibited no significant decrease in DDT or
carbaryl. Malathion residues, however, decreased by approximately
30 percent during a 7-day storage period.
The effect of commercial and home preparation on DDT residues in
potatoes grown on soil treated by from 19.1 to 23.2 lbs./acre DDT was
investigated by Lamb et al., (16). Commercial washing operations re-
moved approximately 20 percent of the total DDT residue from po-
tatoes whereas lye peeling plus washing removed about 94 percent.
Following washing, commercial processing further reduced the resi-
due to insignificant levels. Peeling removed more than 91 percent of
the residue during home preparative procedures. No significant loss
of DDT residue was exhibited by potatoes stored at 45° F. for a period
of 6 weeks.
141
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Gunther et al(17) found that the half-life values for Guthion
under dry field conditions was 30 to 38 days for lemons and 340 to 400
days for oranges. Rainfall or washing markedly decreased the Guthion
residues. Guthion is largely nonpenetrating, therefore, and relatively
persistent on these f raits, but may be removed easily.
CITED REFERENCES
(J) Lichtenstein, E. P., Schtjlz, K. R., Screutny, R. F., and Stitt, P. A.:
Insecticidal residues in cucumbers and alfalfa grown on aldrin- or hep-
tachlor-treated soils. J. Econ. Eutomol. 58: 742-746,1965.
(2) Wood, T. K., Gyrisco, G. G., Gutenmann, W. H., and Edwards, C. H.: The
presence and persistence of dieldrin on forage crops from soil treatments
for alfalfa snout beetle (Brachyrhinua liqustici) control. J. Econ. Entomol
59 : 472-473,1966.
(3) Bruce, W. N., Decker, G. C., and Wilson, J. G.: The relationship of the
levels of insecticide contamination of crop seeds to their fat content and
soil concentration of aldrin, heptachlor, and heptachlor epoxide. J. Econ.
Entomol. 59:179-181, 1966.
(4) Nash, R. G.: Plant absorption of dieldrin, DDT, and endrin from soils.
Agron, J. 60: 217-219,1968.
(5) Mann, G. S., and Chopra, S. L.: Residues of carbaryl on crops. Pat.
Mon. J. 2:163-166,1969.
(6) Duggan, R. E., and Lipscomb, G. Q.: Dietary intake of pesticide chemicals
in the United States (II), June 1966-April 1968, Pest. Mon. J. 2:153-
162,1969.
(7) Rusoff, L. L.t Temple, R. S., Myers, R. G., Newsom, L. D., Burns, E. C.,
Barthel, W. F., Corley, C., and Allsman, A.: Residues in fatty tissues
and meat of cattle grazing on pastures treated with granular heptachlor.
J. Agr. Food Chcm. 11: 289-291,1963.
(S) Claijorn, II. V., Mann, H. D., Ivey, M. C., Radeleff, R. D., and Woodard,
G. T.: Excretion of toxaphene and Strobane in the milk of dairy cows.
J. Agr. Food Chcm., 11: 286-289,1963.
(9) Claborn, H. V., Roberts, R. H., Mann, H. D., Bowman, M. C., Ivey, M. C.,
Weidenbacii, C. P., and Radeleff, R. D.: Residues in body tissues of
livestock sprayed with Sevin or given Kevin in the diet. J. ]Agr. Food
Chcm. 11: 74-76,1963.
(10) Zweio, G., Smith, L. M., Peoples, S. A., and Cox, R.: DDT residues in
milk from dairy cows fed low levels of DDT in their daily rations. J. Agr.
Chcm. 9: 481-484,1961.
(11) Zwexg, G,, Pye, E. L., Sitlani, R., and Peoples, S. A.: Residues in milk
from dairy cows fed low levels of toxaphene in their daily ration. J. Agr.
Food Chcm. 11: 70-72,1963.
(12) Loeffler, W. W., Jr., Trimberqer, G. W., Fox, F. H., Ridgeway, R. L.,
Lisk, D. J., and Gyrisco, G. G.: Extent of residues in milk resulting
from use of Guthion-treated forage. J. Agr. Food Chcm. 14 : 46-47, 1966.
(13) Moubby, R. J,, Myrdal, G. R., and Sturges, A.: Rate of decline of
chlorinated hydrocarbon pesticides in dairy milk, Pent. Mon. J. 2: 72-79,
1968.
(14) Koivistoinen, p., Kononen, M., Karinfa, a., and Roine, p.: Stability of
raalathion residues in food processing and storage. J. Agr. Food Chem.
12: 557-560,1964.
142
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(15) Farrow, R. P., Lamb, F. C., Cook, R. W., Kimbali., J. R., and Elkins, E. R.:
Removal of DDT, malathion, and carbaryl from tomatoes by commer-
cial and home preparative methods. J. Agr. Food Chcm. 16: 65-71, 1968.
(IS) Lamb, F. C., Farrow, R. I\, Elkins, E. R., Cook, R W., and Kimball, J. R.:
Behavior of DDT in potatoes during commercial and home preparation.
J. Agr. Food Chcm. 16: 272-275,1968.
(17) Guntiier, F. A., Carman, G. E., Blinn, R C., and Babkley, J. H.: Per-
sistence of residues of Guthion on and in mature lemons and oranges and
in laboratory processed citrus "pulp" cattle feed. J. Agr. Food Chcm.
11: 424-427,1963.
Soil Contamination
The fall-out of pesticides following sprayed applications in the di-
rect treatment of soil has led to a build-up in the soil of various
amounts of pesticides. Soil residues may, therefore, be a cause for con-
cern since they may reach man by a number of routes: uptake from
soil by consumable crops; leaching into water supplies; volatilization
into the air: and by direct contact with the soil. The magnitude of the
problem is directly related to the amount supplied to the soil and the
rates of pesticide degradation in the soil. The problem can be minimized
by reducing the amounts of pesticides reaching the soil by more effec-
tive application procedures, by using pesticides that have a low per-
sistence so that once they reach the soil they remain only for Short
periods or by the use of pesticides of relatively low toxicity.
In order to reduce the hazards of soil contamination, it is necessary
to understand and utilize the mechanisms which affect pesticides per-
sistence in soil so that for any given application the correct parameters
may be measured and evaluated. The factors which must be considered
include: (1) Pesticide type and formulation; (2) pesticide adsorption;
(3) soil type; (4) soil moisture and temperature; (5) uptake by
plants; (6) leaching of pesticides from soil by water; and (7) wind
erosion.
Pesticide type mid formulation,—The persistence of a pesticide is
related to all of the factors enumerated above as there are many bio-
logical, chemical and physical mechanisms of pesticide removal from
soil, each acting differently depending on the chemical structure of
the pesticide. For example, chlorinated hydrocarbon compounds are
less amenable to bacterial breakdown than are the organophosphates.
The formulation and application method used may influence a pesti-
cide's longevity in soil. Lichtenstein (7), for example, found that
aldrin residues on the soil surface decreased more rapidly than resi-
dues beneath the surface, no doubt because of a greater exposure of the
chemical and physical effects of weathering. It was also found that
granular applications of Guthion were more persistent than emulsions.
Pesticide adsorption and soil type.—The phenomenon of pesticide
adsorption is intimately related to the particular pesticide in question
143
37J.-O70: O—60, 11
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and the type of soil in which it is found. The nature of the colloidal
soil particles, whether they are high in organic content or are of clay
or sandy composition, affects adsorption. The solubility of the pesti-
cide and the pH of the soil also affect soil adsorption. Some pesticides
are absorbed more rapidly under moist conditions and some under dry.
Most pesticides are adsorbed to a greater extent at cool temperatures
than under high temperature conditions but not all. In short, there
are few general statements about adsorption that can be made con-
cerning all pesticides. Each compound reacts to the influencing fac-
tors in an individual manner.
Soil moisture and temperature.—In addition to affecting adsorption
raites of pesticides on soil particles, the moisture and temperature of
the soil may also affect microbial activity. High moisture content en-
hances the degradative process of hydrolysis by microorganisms. Tem-
perature also affects the biological breakdown of pesticides, the solu-
bility of the pesticides, and the amount of volatilization which occurs.
Uptake by plants,—Some pesticides are translocated from the soil
into plants or crops. Lichenstein (2) found that potatoes, radishes,
and carrots grown on a loam soil treated with aldrin at 1 lb. per acre
contained 0, 0.03, and 0.05 p.p.m. respectively. Heptachlor-treated
soils yielded greater crop residues than did those treated with aldrin.
Thus, this mechanism constitutes a potential exposure hazard for man
since edible crops will take up pesticides from the soil.
Leaching of pesticides from soil by water.—Pesticides held in the
soil may be carried by water with possible subsequent contamination
of water courses, water supplies, and groundwater. Run-off after
either rainfall or irrigation may physically transport particles to
which pesticides adhere or the water may leach the pesticide from the
soil particles. Water was percolated through soils treated with 1 p.p.m.
(=2 lbs. per 6-inch acre) aldrin or parathion (
-------
Tarzwell and Henderson (5) found that the dieldrin concentration
of runoff water from a grassy area treated with 2.66 lbs. per acre de-
creased with time. The dieldrin concentration of water following a
rainfall which occurred one day after treatment was found to be 0.13
p.p.m. The concentration of dieldrin in runoff following a third rain
which occurred 9 days after the treatment was 0.025 p.p.m. No dieldrin
was detected in the runoff following a rainfall later in the 9th day after
treatment.
Nowhere is the argument against using the permanent types of pesti-
cides (e.g. mercury, arsenic and lead) better illustrated than in orchard
areas of the United States where arsenic-containing pesticides have
been in use for decades. In many such areas the arsenic has accumu-
lated in the soil to the point where the soil is toxic, shortening the life
of trees and making difficult the profitable use of orchard lands for
the forage crops that normally follow orchards in rotation (6).
Wind erosion.—Another possible hazard to the general public from
soils contaminated with pesticides is that of wind erosion. With appro-
priate conditions of soil, moisture, humidity, and wind, pesticide resi-
dues from the soil may find their way into the air and be transmitted
for great distances from the original source of application. (See section
C, The Air Route.)
Cited, References
(J) Lichtenstein, E. P.: Soil and plant interactions with pesticides. Progress
Rept, Univ. "Wisconsin, Madison, 1966,28 pp.
(2) Lighten btein, E. P.: Persistence and behavior of peetlcidal residues in soils.
1Arch. Envir. Health 10:825-826,1965.
(3) Lichtenstein, E. P., Schulz, K. R,, Skrentny, R. F., and Tsdkano, Y.:
Toxicity and fate of insecticide residues in water. Arch. Envir. Health
12:199-212,1906.
(4) Nicholson, H. P., Webb, H. J., Laves, G. J., O'Brien, R. E., Gbzenda, A. R.,
and Shanklin, D. W.: Insecticide contamination in a farm pond. Tran».
Am. Fish 8oc. 91:213-222,1962.
(5) Tarzwell, C. M. and Henderson, C.: Toxicity of dieldrin to fish. Trans.
Am. Fish Soc. 86: 245-257,1956.
Jones, J. S. and Hatch, M. B.: Spray residues and crop assimilation of
arsenic and lead. Soil Science, 60: 277-288,1945.
Household Use
The use of pesticides for domestic purposes has become widespread.
Accompanying this increased application is an increased danger of
misuse, accidental poisoning and increased contamination of the home
environment. Homeowners are seldow acquainted with the scientific
rationale of safe application and frequently fail to read and under-
stand the instructions contained in the label. Thus, problems of over-
145
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use and misapplication have reached the point where contamination
by household pesticides may constitute a significant proportion of
the total population exposure.
Of special concern is the development of a large number of pesti-
cide dispensing devices intended to simplify the reduction of pests
in the household. Shelf paper impregnated with pesticides and evapo-
rators intended to produce an insecticide aerosol for insect control
are examples of potentially hazardous installations in closed environ-
ments. Pesticides have been incorporated in paints, furnace filters,
swimming pool chemicals for algae control, and in various types of
automatic dispensers, all of which may provide problems of exces-
sive pesticides in the living environment of the household. Garden
hose atomizers have been developed for home use with a variety of
pesticides. These devices have the potential of causing back-siphonage
in which situations highly toxic pesticide materials can be intro-
duced into the home drinking water system.
Little information is available concerning the total amounts of
household pesticides used in the United States. A study of Salt Lake
County, Utah, from July, 1967, to July 1968, is illustrative of the
amounts of household chemicals in use and indicates the proportion
of the total amount of pesticides applied that may be attributed to
domestic use (J).
In Salt Lake County, with an area of 764 sq< miles and a population
of about 440,000, a total of 200,811 lbs of pesticide were applied during
the 1-year study period. The amounts used in the various types of
application are as follows:
Use Pound»
Domestic 102,490
Agricultural
Farm 36,511
Commercial Applicators 18,722
Fruit 14,540
Government Agencies 12, 871
Mosquito Abatement 12,871
Live Stock 2,860
Total 200,865
In this county, therefore, domestic pesticide use accounted for ap-
proximately one-half the pesticides. These amounts would vary de-
pending on the degree of agricultural activity in a given area but
illustrate the large amounts of pesticides that are being used domes-
tically in some areas.
Of the 102,490 lbs applied domestically, the amounts of the impor-
tant pesticides used were as follows:
146
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Pesticides Pounds
Arsenic 81, 783
Chlordane 5, 876
2,4,5-T and 2,4-D 5, 790
DDVP 2,890
Malathion 1, 380
DDT 1,108
Other 3, 663
The inorganic pesticide arsenic, therefore, accounted for approxi-
mately 80 percent of the domestic pesticides used.
A different usage pattern was found in Arizona by the Arizona
Community Pesticide Studies Project which contrasted the domestic
usage of pesticides with agricultural usage for the year 1968 (2). The
findings were based on 475,362 households in the state and a crop
acreage of 1,204,000 acres and are presented below.
Pesticide group House and garden Agricultural use—
use—1968 1968
lbs. tteh. Ibi. tech,
material material
Chlorinated hydrocarbons
28,
600
4,
202,
000
Herbicides ..
12,
690
870,
000
Organophosphates . -
11,
590
2,
839,
200
Miscellaneous insecticides
5,
600
263,
600
Fungicides.. - -
2,
600
126,
000
Carbamates
1,
900
153,
400
Defoliants and desaicants.
1,
084,
100
Total
62,
980
9,
538,
300
Thus, in contrast to the findings in Salt Lake County where a high
arsenic domestic usage was found, the group of chlorinated hydro-
carbon pesticides accounted for approximately 45.5 percent of the
pesticides used domestically. Also, whereas the domestic usage of pesti-
cides in Salt Lake County accounted for approximately 50 percent
of the total, domestic usage in the state of Arizona accounted for only
about 0.6 percent of the total.
All people, of course, do not use pesticdes in their homes and
gardens in equal amounts. Finklea et al. (3), for example, surveyed
Charleston, South Carolina, and found that whereas 83 percent of
the white families sampled used pesticides in their home, 97 percent
of the nonwhite families employed household chemicals for pest con-
trol. It was observed that the homes of nonwhite families were more
frequently infested with roaches, mosquitoes and flies. Nonwhites
therefore applied pesticides inside their homes more intensely than
did whites. Yard and garden applications, however, were found prin-
147
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cipally among whites. Thus, the differences in application were prob-
ably attributable to differences in economic status and housing quality.
Both white and nonwhite families commonly ignored safety precau-
tions in the use of household chemicals. Locked storage was not em-
ployed by 88 percent of all families; 66 percent stored the pesticides
within easy reach of small children; 54 percent stored the chemicals
near food or medicine; and 66 percent never wore protective gloves dur-
ing use or washed their hands after the application.
This stxidy indicates that lower socioeconomic groups may use
pesticides in greater amounts than higher socioeconomic levels but that
both groups tend to disregard safe practices in the application and the
storage of these poisons.
Da vies and Carter (4) observed differences in DDE blood levels in
children living in different ureas of Dade County, Florida. Some of
the children in the poorer sections exhibited DDE blood levels as high
as those found in adults. The authors hypothesized that the pesticide
blood levels could be correlated with the dust levels in the homes, as
the poorer homes tended to have higher dust levels than other homes.
Poorer homes had many roaches and therefore a greater dependence on
insecticides prevailed in these homes. Also, since DDT is one of the
cheaper pesticides, the poorer families favored its use. The younger
children, therefore, would be most likely to be exposed to the dust as
they crawled upon the floor. To test this hypothesis, kittens were placed
in a clean home in good repair and in one of the poorer homes. The kit-
ten in the clean home exhibited no increase of DDT and DDE blood
levels during the study period of four months. The kitten in the
poorer home, however, exhibited a rise of DDT from 12 p.p.b. to 120
p.p.b. and in DDE from 10 to 20 p.p.b. during this same period. The
average blood DDE in the four children in this house was 39 p.p.b.
Both, homes were given the same cat food. Therefore, even though
the number of kittens in the experiment was not large, a demonstrable
difference in blood DDT and DDE levels was observed, indicating that
general household conditions may have an effect on the possible expo-
sure to children when all other factors are equal.
Several studies have attempted to correlate environmental pesti-
cide levels attributable to domestic usage with pesticide blood levels
or respiratory performance. Weiner and Worth (J) studied two
groups with similar income, educational level, occupations, residences,
and ethnic background to determine the relationship between insec-
ticide use and respiratory impairment. The heavy-use group applied
pesticides once a week or more often and the light-use group used
pesticides less than once a week. Tests of forced expiratory volume
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and forced vital capacity revealed that people in the consistently
light pesticide use group performed significantly better than those
in households vising insecticides heavily. There was no definite corre-
lation between respiratory impairment and a particular pesticide
nor could any other environmental variable be attributed to the dif-
ferences in respiratory function. More asthma and chronic sinusitis
were observed in the heavy-use group and perennial nasal allergy
was twice as common in this group.
A comparison of the exposure to lindane from home vaporizers
with that of occupational exposure levels is provided by a study in
California (6). Several groups of people, ea/ch having various expo-
sures to lindane were studied. Lindane blood levels and air concentra-
tions to which they were exposed were sampled. The results are
summarized below:
Lindane in whole
blood—p.p.b. Lindane air
concentration—
Sample population Mean Range mgXHH/m1
Control—No exposure 0. 46 0. 3-0. 9
Nonproduction workers in lindane plants.
0.
S3
0.
3-2.
5
9. 0-49
Production workers in plant 1 with little or no
skin contact - _ . __ _ _
4.
6
1.
9-8.
3
31-1800
Production workers in plant 2 with little or no
skin contact—
4.
1
1.
0-8.
9
11-1170
Production workers in plant 2 with ample
skin contact
30.
6
6.
0-93. 0
11-1170
Lindane exposure from home vaporizers only—
2.
2
0.
9-5.
2
1. 0-110
The exposure to lindane home vaporizers produced greater blood
concentrations than nonproduction workers experienced in lindane
plants and in some cases, as evidenced by the overlapping ranges,
produced blood levels higher than in production workers in lindane
plants. Lindane air concentrations attributable to lindane home vapor-
izers were at times as high as those concentrations in the lindane
manufacturing plants.
In summary, the data presented indicate that the use of household
pesticides, while high for all groups, is greater in lower socio-eco-
nomic levels than in high. This fact, together with the generally less
clean conditions found in poorer homes, indicates that people of
lower economic levels may receive a higher exposure to household
pesticides than other segments of the population. All groups tend to
disregard the labeled instructions for safe application and storage.
Respiratory impairment and high blood pesticide levels have been
correlated with heavy pesticide use.
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An additional potential household exposure is provided by contact
with wearing apparel that has been treated with pesticides for moth-
proofing. A survey of dry cleaning establishments in three counties of
Mississippi was conducted by the Mississippi Community Studies
Pesticide Project in an attempt to detetrmine the number of firms
which employed such practices and the pesticides involved (7). Forty-
one dry cleaning firms were questioned about their mothproofing pro-
cedures during the year 1968. Of the dry cleaners studied, 16 used no
mothproofing agents while 25 did use such products. When mothproof-
ing agents were employed, it was generally the practice to mix a quan-
tity of tihe agent with the regular dry cleaning fluid. Thus, in these
firms, every article of clothing which was dry cleaned was moth-
proofed as well, regardless of whether the customer had requested
mothproofing. Mothproofing generally began in April or May and
ended in July, August, or September. One dry cleaning firm used moth-
proofing year round.
Four main mothproofing chemicals were used: Sanex, Milo, Tri-
pruf, and Sanitone. All four products contained DDT, although Sam-
tone, which was 100 percent DDT, was the only product in which the
DDT concentration was identified. The maximum volume of moth-
proofing chemical used during 1968 by any firm was 20 gallons; the
maximum weight was 75 pounds.
In most cases, only one or two employees in a given firm had direct
contact with the mothproofing chemical. The estimated number of
families affected, however, was always in the hundreds, and in some
instances, it was in the thousands. A large number oif customers was
therefore exposed to DDT by the mothproofing practices of these dry
cleaning firms.
Commercial pest control.-—Throughout the nation there are large
numbers of commercial pest control operators who work extensively
in private dwellings and institutions in the control of household pests.
In 1963 there were 5223 firms concerned with structural pest control
and exterminating services and the number continues to grow. The an-
nual gross income from these operations is estimated to be over 450
million dollars of which about 30 to 40 million dollars is spent on the
purchase of pesticides (5).
The 10 most important pests controlled by pest control operators in
1965 were as follows:
1. German roach.
2. House mouse.
a Norway rat.
4. Subterranean termites.
5. House ants.
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6. American roach.
7. Carpenter ants,
8. Oriental roach.
9. Fleas.
10. Brown dog tick.
The German cockroach and the two commensal rodents are the
three most important pests encountered and require frequent, usually
monthly, control. Although fourth on the list of important pests, ter-
mite control accounts for about 35 percent of the industry's income.
The most important insecticides for household use are as follows:
1. Diazinon spray.
2. Chtordane spray,
3. DDVP Spray additive.
4. "Kepone" pellets.
r>- DDT dust.
6. Pyrethrins and synergist
7. "Baygon."
8. Sodium fluoride.
0. DDVP spray.
Diazinon is an organophosphate, is the most frequently used insec-
ticide for indoor work and is effective against most chlorinated hydro-
carbon resistant roaches. Chlordane is very effective against ants and
most species of cockroaches and is used for the control of many minor
pests because of its long residual action, low odor and moderate
mammalian toxicity. DDVP is used to provide a quick knockdown in
conjunction with more persistent chemicals such as Diazinon and
chlordane. The use of Kepone pellets as baits has increased even
though it is relatively slow acting. DDT dusts are used as a trailing
powder to control mice and for the control of cockroaches. Pyrethrins
are used as knockdown sprays and in food processing and storage.
Baygon, a carbamate, is used to control chlorinated hydrocarbon re-
sistant cockroaches. Sodium fluoride is often mixed with pyrethrum
for dusting walls and concealed areas.
Anticoagulants, such as Kepone pellets referred to above, are used
extensively by pest control operators for the control of rodents. Their
nse is primarily as a bait to maintain low population levels after
the rodent numbers have been reduced. Water solutions of anticoagu-
lants are sometimes used, as are tracking powders, but the most com-
mon method employed is that of solid baits. Although anticoagulants
are slow acting, their low toxicity makes them quite attractive from
the safety standpoint. These compounds are ineffective against some
rodent populations, however, because of a natural tolerance or resist-
ance and more toxic rodenticides are required in these situations.
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Proper commercial pest control dictates that the chemical and tar-
get pest organism be matched effectively. The pesticide which will
accomplish the greatest kill in the shortest possible time and in the
safest manner is the chemical which should be used. The toxicity of
the pesticide must be balanced with its persistence, however, since
many pest organisms require frequent control. Nonpersistent pesti-
cides may result in uneconomical control frequencies as, for example,
in termite control. More persistent pesticides are therefore often
required and their application must be properly administered to avoid
long-term contamination.
Most commercial pest control operations are under the licensing
jurisdiction of local units of government and in some cases under
State control. The operators, in the main, have demonstrated an
interest in the protection of the health of their employees as well as
protection of the health of the public. The National Pest Control
Association, an organization composed of and sponsored by commer-
cial pest control operators, promotes the safe use of pesticides and
helps in the production and evaluation of new chemicals and control
techniques.
CITED REFERENCES
(1) Utah Community Studies Pesticide Project: Annual Report. Division of
Community Studies, Food and Drug Administration. 1968.
(2) Arizona Community Studies Pesticide Project: Unpublished Data. Divi-
sion of Community Studies, Food and Drug Administration, 1909.
(8) Finklea, J. F„ Keel, J, E„ Sandifer, S. H., and Gadsden, R. H.: Pesticides
and pesticide hazards in urban households. J. 8. Carolina Med. Assoc. 65:
31-33, 1969.
(b) Davies, J. E. and Carter, H.: Annual Report. Florida Community Studies
Pesticide Project. Division of Community Studies, Food and Drug Admin-
istration, 1968.
(5) Weiner, B. P. and Worth, R. M.: Insecticides: Household Use and Respira-
tory Impairment Hawaii Med. J. 28: 283-283,1969.
(6) Milby, T. H. and Miller, D. P: Annual Report. California Community
Studies Pesticide Projeet. Division of Community Studies, Food and Drug
Administration, 1968.
(7) Mississippi Community Studies Pesticide Project: Quarterly Report, Di-
vision of Community Studies, Food and Drug Administration, 1969.
(8) Spear, P. J.: Insecticide needs of pest control operators. Soap and Chemical
Specialties, March, April 1967.
Pesticide Manufacture, Occupational Exposure and Accidents
In the processes of manufacturing and formulating pesticide mate-
rials, industrial employees may be exposed to pesticide gases, fumes,
and dusts, and to skin contact with these chemicals. In many of the
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large manufacturing plants, industrial hygiene and medical super-
vision are available. Among the small manufacturers throughout the
country, however, little attention is given to industrial hygiene prac-
tices and medical supervision is not available.
Hazards to manufacturing employees can be reduced through a
variety of methods, as for example, the installation of appropriate
ventilation equipment. Hartwell and Hayes (1) observed workers
in two organophosphate formulating plants, one with adequate and
the other with inadequate facilities for respiratory protection against
inhalation of airborne contaminants. In both plants, the workers who
loaded and packaged the formulation mixture, the most hazardous
job in the manufacture of pesticides, were studied. Cholinftsterase
activity depressions as a result of pesticide poisoning occurred 41 times
in 26 subjects in the plant with inadequate protection during the first
year of the study. When the plant installed a system which distributed
uncontaminated compressed air to facemasks worn by each worker,
the incidence of pesticide poisoning decreased drastically. The other
plant studied had such a compressed air system but poisonings occurred
due to a faulty design in the air system which allowed a back syphonage
of pesticide-laden air to occur. When this situation was corrected, the
incidence of pesticide poisoning decreased.
Protective clothing may also be employed to protect the workers.
The training and instruction of the workers regarding the hazards
involved in the manufacture of the pesticide, the techniques used for
self-protection, the reasons for this, protection and the procedures to
be followed in case of accidents are perhaps the most important pre-
ventive actions.
It is well known that workers in plants producing persistent pesti-
cides, such as DDT, accumulate much higher levels of the pesticide in
their adipose tissue than the general population. However, Laws et al.
(2) found that even though 35 workers with exposures of more than
11 years at a DDT manufacturing plant had accumulated 38 to 647
p.p.m. DDT as compared to 8 p.p.m. in the general population, no ill
effects were evident. The long-range effects of such high exposures
and accumulation rates are less certain.
Agricultural applications.—In California during 1966, 1,347 acci-
dents were attributed to pesticides and other agricultural chemicals
(3). Accidents in the agricultural use of these chemicals numbered 820
while all other occupations accounted for 527 accidents. The number
of accidents involving these chemicals in terms of the industry where
the accident occurred and the occupation of the injured persons is
reported below.
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By industry By occupation
Accident Agricul- Marmfac- Farm
Agricultural Chemical total tural turlng Other1 laborers Other"
Total 1,347 820 204 323 704 623
Organophosphates 253 183 46 24 152 101
Parathion 102 88 12 2 79 23
Other 151 95 34 22 73 78
Chlorinated Hydro-
carbons 94 49 18 27 42 52
DDT, chlordane,
lindane, kolthane.. 40 19 7 14 17 23
Methyl Bromide 30 17 6 7 17 13
Other 24 13 5 6 8 16
Lead and/or arsenic
compounds 10 7 1 2 7 3
Herbicides 145 90 12 43 80 65
Fertilizers 133 73 37 23 48 85
Other s 712 418 90 204 375 337
' Includes: Construction; transportation; trade; structural peat control; government; and unspecified.
'Includes: Professional; clerical and sales workers; truck drivers; gardeners; and unspecified.
3 Includes: Fungicides; carbamates; sulfur; and 438 unspecified.
Of the accidents caused by known compounds, the organophos-
phates were involved more than any other group. Of these, para-
thion accounted for approximately 40 percent. Herbicides and ferti-
lizers, with approximately the same number of accidents, were
involved in the next highest number of accidents where the pesticide
or chemical was specified. Chlorinated hydrocarbons were involved in
the fourth largest number of accidents. Within this group, DDT,
chlordane, lindane, and Kelthane accounted for approximately 43
percent of the cases and methyl bromide, 32 percent.
There were approximately four times as many accidents involving
agricultural uses as there were industrial accidents. More agricultural
accidents than industrial accidents occurred with every pesticide
group listed.
Farm laborers were involved in more accidents than all other
workers combined, accounting for approximately 5*2 percent of all
reported accidents. The accident rate for each pesticide specified
was higher for the farm laborer category than for any other working
situation.
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Exposure to pesticides from agricultural applications may be ex-
perienced by individuals who apply the pesticide or by agriculture
workers who work in the fields where the pesticide has been applied.
Wolfe et at. (4) studied the health hazards associated with the agri-
cultural application of endrin and dieldrin, two of the more toxic
chlorinated hydrocarbons. The dermal exposure of workers wearing
normal clothing while spraying a 1-percent formulation of endrin
dust on potato fields was calculated to be 18.7 mg./hr. The respira-
tory exposure was calculated to be approximately 1.8 percent of a
toxic dose per hour of exposure. While spraying endrin on orchard
cover crops and dieldrin on pear orchards, the calculated exposure
was 0.2 percent and 0.3 percent, respectively, of a toxic dose per
hour. Even though the exposure levels were far below toxic levels,
the fact that chlorinated hydrocarbons are stored in the body fat
must be taken into account when evaluating the hazards of repeated
exposures.
It has been estimated that an average orchard sprayman who wore
no hat or protective clothing on his arms would be exposed to approxi-
mately 7.7 percent of the toxic dose of parathion per hour (5). After
about 13 hours of spraying, therefore, the individual could theoret-
ically become poisoned. Experience has shown that this is not neces-
sarily true, however, and this may be attributed to the slow and/or
incomplete absorption of the pesticide which impinges on the skin.
Therefore, toxicity data must be tempered with knowledge of the
mechanisms of pesticide entrance into the body.
Wolfe et al, (6) determined values for dermal, respiratory, and total
exposure in terms of the fraction of toxic dose for 31 different work
activities associated with the pesticide application of 10 different pesti-
cides. Wind was the most important environmental condition studied,
as the amount and direction of wind directly affected exposure levels.
For each pesticide, there appeared to be a significant variation in the
hazard depending on the type of activity in which the worker was
engaged. For example, the hazard from the indoor house spraying of
DDT was about four times as great as flagging for airplane dusting
of fruit orchards, about seven times as hazardous as outdoor house
spraying, and over 30 times as hazardous as operating an air blast
spray machine in a fruit orchard. The loader received about three times
as much exposure as the pilot and about 4y2 &s much as the flagman.
The method and rate of application also affected the potential ex-
posure. For example, the potential exposure while operating an air
blast machine spraying tree orchards with parathion was about 12 times
as great as the exposure when spraying the same compound on row
crops with a boom-type sprayer. The air blast machine sprays the
pesticide up into the air where it is more subject to drift whereas the
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boom-type sprayer directs the spray downward. Increases in the appli-
cation rate would also be expected to increase the possible exposure.
In the same way, the amount of time the workman worked at his par-
ticular job would also increase the pesticide exposure.
The potential dermal exposure to each pesticide was much greater
in every work situation studied than the potential respiratory ex-
posure. The respiratory exposure for the various work situations stud-
ied ranged from 0.02 to 5.8 percent of the total exposure. The use
af low-volume concentrate spraying of parathion in fruit orchards
resulted in a respiratory exposure about three times as great as that
observed for similar parathion applications using conventional high-
volume spray. This is undoubtedly due to the fact that the low-volume
concentrate spraying results in particles of significantly smaller size
than conventional sprays.
Only three of the compounds studied, endrin, parathion, and TEPP,
were involved in operations in which the mean value for the percentage
of toxic dose potentially absorbed per hour exceeded 1 percent. The
highest potential exposure was observed for workers who loaded air-
planes with 1 percent TEPP dust. They received 44.2 percent of the
toxic dose per hour of work. Although the fraction of toxic dose re-
ceived during application of some of the less toxic chlorinated hydro-
carbon pesticides was comparatively low, these compounds are, as
noted previously, stored in the body fat following absorption. No
manifestations of such pesticide exposure have been observed, however.
In cases where poisoning did occur, it was possible to show an obvious
disregard of one or more of the safety regulations. Thus, this study
affirms that pesticides can be used safely provided recommended pre-
cautions are followed.
Quinby and Lemmon (7) studied the potential exposure of workers
engaged in picking, thinning, cultivating, and irrigating various crops
to which parathion had been applied. Eleven cases of poisoning in-
volving more than 70 persons occurred from contact with the parathion
residues. Since the air concentration of parathion over the crops
was extremely low, it appeared that most of the affected workers were
exposed primarily by the dermal rather than the respiratory route.
Also, it was observed that many of the workers removed their protective
clothing and wore contaminated clothing for long periods of time.
Thus, these poisonings were a direct result of working with and
handling contaminated crops.
In all cases where individuals work with pesticides, it is essential
that they be made aware of the problems peculiar to the particular
chemical exposure and that they become familiar with methods of
protection.
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Transportation.—In the consideration of problems associated with
contamination of the environment, the possible contamination through
the transportation of pesticides from the point of manufacture to the
point of final application must be considered. The equipment designed
for transportaion of large volumes of pesticide, which in case of acci-
dent could cause hazard to numbers of individuals, require a design
such that accidents would be prevented insofar as possible. Tank cars,
trucks, and pesticide containers need to be designed in such a manner
that mishandling, which frequently occurs in shipment, will not cause
accidents to the individuals handling the material or to the general
public. It is essential that equipment used in handling and disseminat-
ing pesticides be adequately and properly maintained, so that spills
and the escape of pesticides is avoided.
There is also a need to prevent food contamination with pesticides,
particularly in shipment. A number of cases have been reported in
which pesticide materials shipped with foodstuffs contaminated large
volumes of food, thereby causing subsequent illness and death.
To minimize such occurrences, the simultaneous shipment of pesti-
cides and foodstuffs should be avoided. In fact, vehicles used for bulk
pesticide shipment should be single-use vehicles; i.e., their use should
be confined solely to the transport of pesticide chemicals.
Contamination of water supplies by accidental spills and the con-
tamination of grain used subsequently to make flour has also been ex-
perienced. In all cases, consideration must be given to the instruction
of the individual handling the material concerning the hazardous na-
ture of the chemical involved.
Accidents.—A large number of accidents from pesticides occur each
year. For example, in 1961, 8.5 percent of all cases of accidents and
poisoning of children younger than 5 years of age in the United States
was attributed to pesticides (5). Of the 32,034 reported cases, 16,119
were caused by medicines, 1,726 by petroleum products, and 2,709 by
pesticides.
In South Carolina, between 1957 and 1966,38 deaths were attributed
to pesticide usage (9). Most poisonings occurred in areas of high pesti-
cide application and 60 percent of the fatalities occurred in children
under 5 years of age. Parathion accounted for 34.2 percent of the poi-
sonings and arsenic 31.6 percent.
In Dade County, Fla., studies of the pesticide mortality records for
the years 1956-67 revealed that children under 5 years of age ac-
counted for 23 percent of the fatal poisonings (10). These deaths were
primarily due to accidental ingestion of the pesticides in and around
the home. In addition to the children, young to middle age adult
mules who were occupationally poisoned and middle age to older adults
who suicidally ingested pesticides accounted for the majority of the
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fatal and nonfatal pesticide poisonings. Organophosphate pesticides
accounted for 53 percent of the fatal poisonings.
McLeod and Herban (11) studied the pesticide mortalities which
occurred in Louisiana between 1958 and 1967. Pesticides were the cause
of 102 deaths during this period. The 10-year cumulative death rate
from pesticides per 100,000 population are as follows:
Pesticide ingestion accounted for 75 out of the 102 cases. Mo9t of
the poisonings in infants and children were accidental whereas poison-
ings in adults were primarily suicides. Only three deaths were occupa-
tional and these were all agricultural. Arsenic accounted for 37 deaths;
unknown pesticides 21; inorganic phosphorus 12; fluoride 10; and
organophosphates 9.
McLeod (12) also studied the 107 cases of pesticide poisoning in
patients admitted to Charity Hospital in New Orleans from July
1965, through June 1967. Children less than 5 years of age accounted
for 77.6 percent of these cases. In comparison with the total admis-
sions to the hospital, a greater proportion of the pesticide poisoning
patients were Negro. Most of the adult poisonings were the result of
suicidal attempts whereas the poisoning of children occurred through
accidental ingestion. Pesticide mixtures accounted for 26.1 percent
of the poisonings; Fumarin and Warfarin 20.6 percent; organophos-
phates 15.9 percent; and chlorinated hydrocarbons 4.6 percent.
The above studies indicate that children who accidentally ingest
pesticides in the home account for a large proportion of the accidental
poisonings attributable to pesticides. Efforts aimed at the reduction
of accidental poisonings, therefore, must be directed toward the mini-
mizing of children-pesticide contact in the home environment. No
single pesticide or pesticide formulation has been incriminated as
being a major cause of accidental poisoning. The availability or ease
of access to the pesticide would seem to be more important than the
type of chemical involved.
Accidental exposures to pesticides occur through inhalation, direct
consumption of contaminated food, and through skin absorption.
Coble et al. (13) reports the accidental poisoning of several people
by flour contaminated with endrin. Although no human fatalities
resulted, the bread which caused the poisoning killed a rat within
12 hours after feeding and caused dogs to convulse. Extracts from
White:
Accidents
Suicide. _.
0. 48
1. 94
Nonwhite:
Accidents
Suicides..
2. 21
0. 62
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the flour sacks killed a dog 2 hours following ingestion. How the flour
became contaminated was not known.
The packaging of pesticide products is an important consideration
in the reduction of accidents, whether in the manufacturing plant,
during shipment, in stores or in homes, Defective packages or pack-
ages which might rupture during rough handling must be avoided.
The use of package materials which will not weaken during long
periods of storage due to degrad&tive processes such as corrosion
should be made mandatory.
Another problem is that of the disposal of used pesticide containers.
Large containers may contain appreciably amounts of pesticides
after use. For example, Wolfe et al (14) fofand that 22 empty 5-gallon
metal drums which had obtained 45.6 percent parathion emulsifiabJe
concentrate contained an average of 2.73 gm. of technical parathion
in suspension. Tests indicated that rinsing the containers twice with
water removed almost 98 percent of the removable parathion. The
disposal of the rinse water presents additional problems, the solu-
tion to which may be the shipment of unrinsed bulk containers back
to the manufacturer who, presumably, would have the facilities neces-
sary to clean the containers, dispose of the rinse water and dispose of
or reuse the containers, and at the same time insure that the con-
tainers would not be reused for packaging foods or the like.
The incorrect disposal of containers used for household pesticides
constitutes a hazard to man and hi8 environment. It is important,
for example, that glass or metal containers be disposed of soon after
their contents have been emptied in order that they may not be used
for drinking water jugs or other household purposes or remain avail-
able for possible contact with children. The present day disposal meth-
ods, namely incineration (as presently practiced, time-temperature
aspects are insufficient for pyrolysis) or burial in the ground, are
unsatisfactory in that even though they minimize the immediate
dangers of exposure, they contribute to the buildup of environmental
contamination. A solution offered for the disposal of bulk containers
may not be practical with regard to the many smaller bags, bottles,
boxes, cans, etc., sold to the public each year. Obviously, a more sat-
isfactory solution to this problem must be found. In this connection,
information as to the proper disposal of old, unsold stock or of dis-
continued pesticides should be made available to all pesticide users.
The accidental incorporation of massive levels of granular or powder
insecticides in animal feed in place of the intended mineral is a pri-
ma^ source of pesticide problems in livestock. Animals that die from
such exposures are disposed of in rendering plants and end up in
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371-074 o—eft—ie
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meat scraps and tankage fed to animals, thus contributing to
pesticide residues in foods for humans.
In order to prevent accidents of the types listed above, one of the
important aspects is that of labeling, coloring, or otherwise clearly
marking pesticides in such a manner that will bring to the atten-
tion of users the hazards which exist. It is important that the user
of pesticides be thoroughly and forcibly warned of the hazardous
nature of the material and the reasons for the precautions which are
recommended. Problems of storage need to be given adequate atten-
tion, particularly in relation to storage of household pesticides so
as to prevent their availability to children.
The possibility of sales control through appropriate registration
of the more hazardous pesticides should be given attention.
CITED REFERENCES
(1) Hartweli,, W. V. and Hayes, G. R.: Respiratory exposure to organic phos-
phorus insecticides. Arch Envir. Health 11 :r>64-568, 1965.
(2) Laws, E. R., Curley, A., and Bibos, F. J.: Men with intensive occupational
exposure to DDT. A clinical and chemical study. Arch Envir. Health
15 :766-775,1967.
(3) California, State of: Occupational Disease in Calfornia Attributed to
Pesticides and Other Agricultural Chemicals—1966. Department of Pub-
lic Health, Bureau of Occupational Health. Berkeley, Calif, (undated),
25 pp.
ib) Wolfe, H. R., Durham, W. F., and Armstrong, J. F.: Health hazards of
the pesticides endrin and dieldrin. Arch Envir. Health 6:458-464, 1963.
(5) Wolfe, H. R.: Health hazards in the agricultural use of economic poisons.
Wash. St. Weed Control Proc., 1960, pp. 3—8.
(6) Wolfe, H. R., Durham, W. F., and Armstrong, J. F.: Exposure of workers
to pesticides. Arch. Env. Health 14:622-633, 1967.
(7) Quinby, G. E. and Lemmon, A, B.: Parathion residues as a cause of poison-
ing in crop workers. J. Am. Med. Assoc. 166:740-746, 1958.
(8) Cann, H. M.: Pesticide poisoning accidents among young children. Am. J.
Pub. Health 53 :1418-1426, 1968.
(9) Pietsch, R. L., Finkxea, J. F., and Keil, J. E.: Pesticide poisoning in South
Carolina. J. S. Carolina Med. Assoc. 64:225-228, 1968.
(10) Retch, G. A., Davis, J. H., and Davies, J. E.: Pesticide poisoning in South
Florida. An analysis of mortality and morbidity and a comparison of
sources of incidence data. Arch. Envir. Health 17:708-775, 1968.
(11) MoLeod, A. R. and IIerban, N. Ij. : Mortality from pesticides in Louisiana,
1958 to 1967. J. Louisiana St. Med. Soc., (In press).
(12) McLeod, A. R.: An epidemiologic study of pesticide poisonings in patients
admitted to Charity Hospital, New Orleans. J. Louisiana St, Med. Soc,,
(In press).
(13) Coble, Y. Hildebrandt, P., Davis, J., Raascii, F., and Curley, A.: Acute
endrin poisoning. J, Am. Med. Assoc. 202: 489-493,1967.
(14) Wolfe, H. R„ Durham, W. F., Walker, K. C., and Armstrong, J. F.:
Health hazards of discarded pesticide containers. Arch. Envir. Health
3:531-537,1961.
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Alternative Pest Control Measures
Alternatives to persistent pesticides may be of two main types. First,
nonpersistent pesticides may be substituted for persistent materials.
Secondly, pest control procedures which do not utilize toxic chemicals
may be employed. Such alternative methods are usually of a biological
or physical nature but their use has been limited up to this time, al-
though much research has gone into the development of these tech-
niques. An increased emphasis is being placed on nonpesticide control
methods, with more than 50 percent of the Agricultural Research Serv-
ice entomological research budget in 1967 devoted to these alternative
techniques. Since more than 90 percent of the total amount of pesti-
cides used are employed for the control of fewer than 100 species of
pest organisms, the reduction of these specific pest populations by non-
chemical methods would significantly reduce the pesticide burden.
In some situations, the establishment of a goal for pesticide treat-
ment of less than a 100 percent kill would not only reduee the amount
of pesticide needed but also would allow the maintenance of beneficial
predators in the community enabling them to continue exerting a nat-
ural population control of the pest organisms.
Development of nonpersistent pesticides.—The development of non-
persistant pesticides has had high priority for the last several years.
The results of this intense effort are already becoming evident as the
trends in pesticide application are to the use of the less persistent
pesticides. For example, the organophosphate compounds are under-
going increased production and use whereas the persistent chlorinated
hydrocarbon compounds are, in general, declining in use. Although
many of the less persistent pesticides are more toxic than the persistent
chemicals, and therefore can exert a greater potential toxic effect on
pesticide handlers and on nontarget organisms, the fact that they
remain viable in the environment for shorter periods of time reduces
the possibility of their entrance into ecological systems with possible
harmful consequences.
Resistant crops,—One of the best methods for protecting crops
against insect injury is the development and use of resistant plant
varieties. The expense of applying sprays and dust, the hazard of
chemical residues, and the danger of developing resistance to pesticides
are all avoided. The development of resistant crops, therefore is a con-
tinuous process of discovery, breeding, and selection of resistant strains.
As the diseases are constantly changing, the resistance of crops to plant
diseases may also vary. Rainfall, temperature, fertility, planting dates,
and soil condition all influence the degree of resistance shown to a
crop disease.
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Resistant plants that have been developed frequently show an im-
provement in yield and quality as a result of more normal growth.
Various strains of wheat, oats, and barley and other grains have been
developed which are resistant to leaf blights and rusts. Various strains
of nongrain plants such as alfalfa, cotton, tobacco, beans, potatoes,
and tomatoes have been developed which are resistant to specific dis-
eases caused by various fungi, bacteria, viruses, and nematodes. The
goal is the development of strains of each type of crop which are re-
sistant to all major types of diseases.
Plants which are resistant to attack by inserts, as for example the
Hessian fly, have been developed. Corn varieties are available that re-
duce cornborer losses by 70 percent. Wheat and alfalfa strains which
are resistant to the particular insects which attack these crops are
being developed and cotton strains resistant to attack by the boll
weevil have been found. The development of resistant, varieties ap-
pears to be the most successful of all noncliemical control methods.
bisect parasites and predators.—The introduction of beneficial para-
sites and predators not native to a particular location and their artifi-
cial growth and distribution is one method by which pests may be
controlled. In addition to the potential lower pest control costs and
avoidance of chemical residues, the widespread substitution of par-
asites or predators for chemical applications would aid in preventing
the danger of developing insect resistance and would also reduce the
possible pesticide injury to the host plant.
There are now at least 95 species of imported parasites and predators
established in the continental United States. Many of these were
brought from Europe to control the gypsy moth, the brown-tail moth,
the European cornborer, and the alfalfa weevil. A large majority of the
introduced species are parasites. There are at least 32 species of par-
asites used in California against scale insects and mealy bugs. Tachinid
flies are used principally against forest and shade tree insects. The
development of techniques which allow for an economical production
of great numbers of parasites has been a large factor in the success
of these efforts. This is necessary so that effective numbers can be re-
leased in areas infested by pest insects.
In spite of some success, there have been only 106 insects anywhere in
the world including 46 in the United States, that have been partially,
substantially or completely controlled by parasites or predators in-
troduced into an area by man (/). For reasons of easier geographical
and ecological control, the greatest successes in this type of treatment
have occurred on islands. This is also true of other means of biological
control and it is a fact that large volumes of pesticides still must be
used to control the organisms to which biological control methods have
been applied despite some success.
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Insect pathogens.—Since insects are subject to infection by disease-
causing organisms, namely, bacteria, viruses, fungi, protozoa, and
nematodes, the use of these organisms offers potential control of pest
insects. The organisms which attack insects are very seldom the same
organisms which attack higher plants and animals, which make them
relatively specific by nature. Various attempts have been made to de-
velop control methods by utilizing disease-producing organisms.
Studies have been made on chinch bugs, grasshoppers, the brown-
tail moth, and the citrus white fly, using fungi as a disease-produeing
agent. The propagation and distribution of fungi, however, is largely
dependent on weather conditions and the results of field studies have
been difficult to evaluate. Another problem with the use of insect fun-
gus diseases is that atmospheric moisture and temperature greatly
affect their dissemination. Warm humid conditions are usually re-
quired for the use of fungi in the control of insects. Bacteria, viruses,
and protozoa, on the other hand, are not so dependent on high relative
humitity for growth and dissemination as are the fungi, These orga-
nisms may be ingested with food or carried by the insect's predators
and parasites, by wind and rain and irrigation water. Weather con-
ditions are important, however, in developing the population densi-
ties required for the control of pest organisms.
Bacteria have been utilized for the control of the Japanese beetle.
Large numbers of beetle grubs are first infected with the bacterium
Bacillus sp. The grubs are then refrigerated until ready for use. At
that time, the grubs are ground up, a dust base is added, and the spore
powders are distributed through areas infested with Japanese beetles.
The bacteria spores are resistant to dryness, moisture, cold and heat,
and may live in the soil for years infecting grubs feeding on grass
roots.
The control of the alfalfa caterpillar has been accomplished by in-
fection with the virus Borrelina campeoles. Infection of these cater-
pillars by this virus can reduce caterpillar populations below economi-
cally important levels in from 5 to 7 days. Supplies of the virus may
be augmented by the continued collection of infected larvae in the
field and their processing to conditions amenable to dissemination.
Micro-organisms used for insect control should not pose a threat to
higher animals or plants. The main difficulties of this type of control
involve the manufacture and dissemination of large amounts of the
microbial material. Also, most of these biological agents are specific by
nature and affect only one pest, allowing other pest insects to live and
flourish once their competition has been reduced. Pathogens also gener-
ally do not produce the quick kills which farmers prefer. Thus, despite
some promise, the pathogenic control of pest organisms must be
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improved substantially before it can become an effective control
technique.
Cultural or environmental control.—The so-called cultural or en-
vironmental techniques for pest control are essentially modifications
of the ecological systems within which the insects operate. One such
approach is the use of induced sexual sterility in which the basic be-
havioral patterns of the insect provide the mechanism of insect control.
In this technique, insects which are sexually sterilized are released
to mate with normal insects thus reducing the population's repro-
ductive potential. If the number of sterile matings is sufficiently
greater than the number of normal matings, the population will
decrease with each generation instead of increasing. When, by con-
tinued release, the number of sterile insects is maintained at a con-
stant level, while the number of normal insects declines, the ratio of
sterile matings to normal matings will increase rapidly in successive
generations.
In many eradication programs, such as the screwworm and melon
fly programs, sterility was induced by irradiation. Since this tech-
nique requires the rearing of insects in the laboratory in large numbers,
it is not applicable to species which are not suited to such laboratory
rearing. In these cases, chemical sterility of a large proportion of the
existing natural population would provide the answer. Ohemosteri-
lants are effective in the control of species in which the males and
females that are produced over a sizable area mix thoroughly before
mating takes place. If both sexes remain near the site at which they
molt to adults until after mating has taken place, chemosterilants
would not be as effective as toxic chemicals. All of the chemosterilants
which are presently in use are presumably mutagenic agents. For this
reason, contact between these chemicals and man or beneficial animals
should be avoided. Species that are attracted to baits and other
attractants are particularly susceptible to such methods. As of
1966 chemosterilants were not recommended for the control of any
species and no large scale experiments in their use had been con-
ducted. Research was under way to develop safe chemosterilants and
to devise safe and effective methods of application.
Regardless of whether the sterility is induced by chemosterilants
or by irradiation, there are certain characteristics necessary for a
species to be controlled by sexual sterilization. The first necessity,
particularly in reference to air-radiation produced sterility, is that
the species be able to be raised economically in large numbers. Species
that produce a large number of eggs per female and have a short
life cycle are most readily amenable to this type of rearing. However,
it is also essential that the sterilized insects do not in themselves con-
stitute a nuisance or a source of injury. Such insects as houseflies
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and cockroaches, or insects which serve as disease vectors, are not
species that can be acceptably controlled by sexual sterility. Species
which are widely distributed or have economic significance also would
not be practically controlled by sexual sterility. Sexual sterility will
achieve maximum success only with species in which the males and
females mix over a considerable area before mating occurs. If the
insects are restricted in their movement it may be difficult to obtain
adequate distribution and placement of sterile insects in required
numbers to compete successfully with the normal insect in the various
parts of the total area. And finally, it is necessary to be able to steri-
lize the species without too serious effects on its vigor, longevity,
behavior, or mating competitiveness.
Another method of effective sterilization of insects is to inject into
the adult insects synthetic juvenile hormones. Juvenile hormones are
produced by the insect's body during metamorphosis to retard the de-
velopment of the adult characteristics. During the final stage of meta-
morphosis the juvenile hormone is not produced, allowing adult
characteristics to develop. When large amounts of synthetic juvenile
hormone are introduced into adult insects, the insects are effectively
sterilized by the degeneration of the adult characteristics. Williams
and Bobbins (2) report on research by Roller which determined that
20 mg. of synthetic juvenile hormone was fully effective in controlling
codling moth infestations in individual apple trees. In other experi-
ments it was found that when the high dose of 1 mg. of synthetic
juvenile hormone was injected into a body of an individual male adult
of Pyrrhocoris apt eras ^ normal females received sufficient juvenile
hormone to sterilize them when mated to the treated male. The con-
taminated females were then in turn able to infect normal males
during later matings, and in many cases, these infected males passed
along sufficient hormone to sterilize yet a further group of normal
females. Thus, if this technique could become effective, the dissemina-
tion of the sterilizing chemical would be enchanced by the normal
activity of the insects themselves.
However, the juvenile hormone may be considered a broad-spectrum
insecticide with a potential for killing beneficial fauna, and hence,
care in its application must be exercised.
Physical pest control methods.—Various types of physical pest con-
trol methods have been developed and are undergoing study in order
to develop their practicality and usefulness. Nelson and Seubert ($)
reviewed new methods of pest control which utilized forms of electro-
magnetic, sonic, and ultrasonic energy.
The use of radiofrequency (RF) electromagnetic energy for the
control of insects has been investigated. Although it has been postu-
lated that RF energy of some particular frequency would be effective
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in killing insects by virtue of some resonance phenomenon, this has
never been demonstrated. It is thought the main lethal action of RF
energy on insects is produced by the heating of the RF electric fields.
The use of RF heating in the control of insects in a large area is im-
practical. The main application of the RF heating effect has been in
the insect control of grain, foodstuffs, and wood. RF heating has been
used to control insects in stored grain without damage to the grain
itself. RF heating has been used for wood disinfestation where in some
cases it might l>e more practical than conventional heating and chem-
ical methods by virtue of its deeper penetration. Little of the RF
energy spectrum has been studied but from the results obtained thus
far this type of electromagnetic energy merits further investigation.
Infrared energy has been used for insect control by radiating grain
on conveyor belts and maintaining lethal temperatures. The use of
infrared energy for the control of insects within large areas has not
proved practical. Attractants which utilize infrared light sources
have had some success.
Visible light, has been used for many years to attract insects. Most
of the common light traps employ blacklight, fluorescent lamps a9the
attractant source. These lamps emit strongly in the ultraviolet region
and attract large numbers of photo{x>sitive insects. Light traps have
been used as an entomological survey device, for detection and quar-
antine work, for the detection of population changes, and the predic-
tion of insect infestations. The use of light traps for the direct con-
trol of insects has been effective in small areas such as vegetable crops
or garden plots and there has been some evidence which suggests thai
the control of insects in larger areas by this method may be possible.
Light traps at a density of three traps per square mile over a circular
area 12 miles in diameter reduced the tobacco hornworm population by
approximately 65 percent in one season. Light traps in combination
with other techniques offer promise. With certain insects, light traps
containing caged virgin females exhibited a higher catch of male
insects than either separately. Light traps might possibly be used in
combination with chemosterilants.
Visible light may be used in other ways to control insects. For ex-
ample, during critical times in the life cycle of certain insects, if the
normal dark period is interrupted by a momentary flash of light, nor-
mal development is prevented, More research into the seasonal cycling
and development of individual insect species must be undertaken so
that techniques such as this can be used effectively.
X-rays and gamma rays, located at the high-energy end of the elec-
tromagnetic spectrum, are extremely penetrating types of radiation.
The effect of their ionizing tissue atoms can lie very damaging if suffi-
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cient energy absorption results from radiation exposure. One use of
ionizing radiation in insect control is that of the sterilization of male
insects as discussed previously. The use of irradiation for disinfecting
grain has also received much attention. Various dose levels applied
to grain are used to either sterilize or kill insects without harming the
grain. Wheat irradiation with 20,000 to 50,000 rads from gamma
sources providing energies of not greater than 2.2 Mev. has been ap-
proved by the Food and Drug Administration. Since studies of gam-
ma irradiation of citrus fruits have shown that low doses of radiation
are effective in controlling eggs and larvae of the Mexican fruit fly,
approval of gamma irradiation for such fruits is also being considered.
When the design of radiation equipment allows it to be used to disinfect
large quantities of grain and other products and the costs of such treat-
ment become more competitive, it is likely that ionizing radiation will
be used to much greater extent in lieu of chemical insecticides.
Other forms of radiant energy, such as sound and ultrasound, have
also been considered for tlheir pest control applicability. They can be
used in two main ways : (1) By causing death directly by heating,
injury to vital organs, or by applying intense energy levels, and (2)
by using lower intensities to which the pests are attracted or their be-
havior affected. Killing pests directly with high intensity sonic and
ultrasonic energy appears impractical because of the cost of produc-
ing the required energy and because the energy can only be applied in
a restricted area. Artificial sounds and recordings of an insect's own
sound have been used to attract insects.
Integrated control techniques.—The joint utilization of several suit-
able techniques to eradicate pests or manage their population levels
is termed integrated control. Integrated control utilizes chemical, bio-
logical, and physical techniques either concurrently or in sequence to
reduce pests to acceptable levels. Integrated control requires a thorough
understanding of the ecology of the pest populations and relies not
only on chemical pesticides, but also natural enemies and all other
factors in the environment which tend to limit pest populations.
Integrated control is desirable because the flexible nature of the
ecosystem allows it to react or adjust to stress in various ways. Thus,
to counteract the reactions of the ecosystem or to lessen the impact
which causes undesirable side reactions, more than one control method
is desirable. For example, rather than applying a large amount of
pesticide for the control of Hessian fly on wheat, smaller amounts of
pesticide together with delayed seeding and the planting of resistant
strains of wheat lessens the flow to the ecosystem, does not produce
such a large ecosystem reaction, and controls the Hession fly in a
more effective and economical manner than by using pesticides alone
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A similar type of integrated control would be the use of light to at-
tract insects to a bait which had been impregnated with a chemical
poison.
The effectiveness of integrated control in pest management is well
illustrated with control of the spotted alfalfa aphid. More than a dozen
insecticide treatments were initially employed for aphid control. When
use of natural enemies and insecticides were judiciously combined,
insecticide treatments were reduced to one. However, integrated con-
trol involves techniques that may appear quite subtle to the nonecol-
ogist, such as special plantings of certain tree types (bald cypress)
on reservoir shorelines (4). Hence, integrated control is likely to be em-
ployed only where knowledgeable personnel are available to initiate
and supervise such a program.
In short, integrated control is the manipulation of all the chemical,
biological, and physical components of the environment for the control
of the pest organism. The proper analysis of the techniques and mea-
sures to be employed requires that a systems design be developed for
the ecosystem in which the pests are found. Ecosystems contain dy-
namic interactions, therefore successful management of the system
must also be flexible and dynamic. To augment integrated control
techniques, fundamentals of ecology, genetics, plant pathology, agron-
omy, and entomology, as well as system analysis, economics, and
biomathematics must be employed.
CITED REFERENCE
(1) DeBach, P. (Ed.) : Biological Control of Insect Pests and Weeds. New York,
Reinhold, 1064, 844 pp.
(2) Williams, C. M and Robbins, W. E.: Conference on insect-plant interactions.
Bioscience 18 r 791-799,1968.
(3) Nelson, S. O. and Seobert, J. L.: Electromagnetic and sonic energy for pest
control. In Scientific Aspects of Pest Control. National Academy of Sci-
ences—National Research Council, Pub. 1402, 1966, 470 pp.
(¦i) Smith, E., Pickard, and Hall, J. F.: Tree plantings for mosquito control.
Mosquito News 29: 161-166, 1969.
Monitoring of Pesticides in the Environment
The initiation of specific monitoring programs for pesticides has
been the result of the very specialized interest of individual govern-
mental agencies. As described below, the Departments of Agriculture,
Interior, and Health, Education, and Welfare all have substantial
roles in pesticides monitoring. Even within these agencies, the respon-
sibilities are divided according to the specific missions of the sub-
agencies such as the Food and Drug Administration, the National Air
Pollution Control Administration and the Environmental Control
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Administration in HEW and the Federal Water Pollution Control
Administration and the U.S. Geological Survey in Interior.
Recognizing the proliferation of studies and responsibilities, a Fed-
eral Committee on Pest Control was established which is charged with
coordination of activities and exchange of information amongst the
agencies involved in pesticide management. The Committee has no
responsibility for initiating activities. Consequently, there are con-
siderable gaps in the monitoring program with the result that an
assessment of the level of pesticides in the biosphere, and how it is
changing, is almost impossible to make. For example, among the
largest reservoirs for the storage of pesticides being added to the
environment are the oceans and yet no agency of the U.S. Government
has responsibility for monitoring pesticide levels in the oceans.
Many ad hoc studies of pesticides in the environment are being made
by various research agencies, and many of these are being reported
in the literature, but there is a need for evaluation of the entire bio-
sphere, the inputs of pesticides to the biosphere, their degradation,
translocation, and storage and their rate of accumulation in the vari-
ous elements of the biosphere. This would help identify elements in
the environment that should be monitored, and help indicate priorities
for the control of pesticide use.
Amongst the more obvious needs in a monitoring program are the
following:
(1) An agency with initiative for instituting monitoring programs
where they are necessary. Such an agency would have responsibility
for overall assessment of pesticide use.
(2) Studies of pesticide levels in the oceans, groundwaters, lakes,
rain, water supplies, waste waters, and in the air.
(3) Studies of pesticides use and levels in the environment outside
the United States. The use of pesticides in agriculture in developing
countries is only in its infancy. Indiscriminate and excessive use of
pesticides, which can be expected because of the technological and
educational level in these countries, will virtually assure that consid-
erable fractions of these pesticides will find their way outside the
countries of application and into the United States amongst other
countries, just as their use in the United States and other industrial-
ized countries has resulted in pesticide accumulations elsewhere in the
world.
(4) Assessments of pesticides levels in biota, with special attention
to levels in fatty tissues of all species of life. For example, bacteria
concentrate pesticides and the accumulation of pesticides in bacteria
in all phases of the environment may involve bacteria as a significant
storage reservoir.
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In addition, there needs to be a large investment in improvement in
analytical methods for monitoring pesticides in all environmental
media, with emphasis on automated monitoring so that data can be
readily stored and amenable to analysis by computer. The continuous
analysis of data gathered in a comprehensive monitoring system would
reveal points of potential danger and permit regulatory control meas-
ures to be instituted before permanent damage is done.
Pesticides in food and feed.—The Federal program for monitoring
pesticide residues in food and feed is comprised of: (1) Surveillance
programs operated by the Food and Drug Administration, U.S.
Department of Health, Education, and Welfare, and (2) pesticide
residues studies of meat samples provided by the Livestock Slaughter
Inspection Division, Consumer and Marketing Service, U.S. Depart-
ment of Agriculture. The objective of this program is to determine pes-
ticide levels in unprocessed and commercially processed consumer food
commodities, animal feeds and composites of food items prepared
for human consumption. Studies include: (1) A continuing market
basket study to determine pesticide levels in the basic 2-week diet of
a 19-year-old male, statistically the Nation's largest eater, and (2)
the nationwide surveillance of unprocessed food and feed.
The Department of Agriculture in 1964 initiated a program spe-
cifically designed to establish pesticide residue profiles in limited
areas. Pilot studies are being conducted in five areas in the Mississippi
River Delta and in Yuma, Ariz., and Grand Forks, N. Dak. Repre-
sentative farms are selected where records of the kinds and amounts
of pesticides used have been kept for 10 to 15 years. The program is
designed to determine existing pesticide levels in soils, sediment, water,
crops, livestock, and certain species of aquatic and land animals
inhabiting the study areas. In addition, soil samples have been ana-
lyzed from 17 locations having high pesticide use histories; 13 loca-
tions where pesticides were used occasionally such as forests and
range lands; and 13 locations on Forest Service lands and national
wildlife areas where no pesticides were reported to have been used.
In the surveillance of domestic and imported meat more than
5,000 samples were obtained in 1965 and 1966 from animals slaugh-
tered in federally inspected establishments.
The Food and Drug Administration surveillance program was ex-
panded substantially in 1963. For several years thereafter, FDA col-
lected and examined about 25,000 samples annually, subjecting them
to multiresidue methods of analysis using gas-liquid chromatography.
Presently, about 9,000 samples are examined annually. Most of these
samples are "objective"; that is, not related to any specific suspicion of
excessive residue and therefore expected to be representative of the
food supply as a whole.
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Pesticides in fish and wildlife.—Efforts to determine pesticide levels
in fish and wildlife are being carried out by the Bureau of Sport Fish-
eries and Wildlife, U.S. Department of the Interior. The monitor-
ing of pesticide levels in clams, oysters, and estuarine sediments is a
ment of the Interior and the Food and Drug Administration of the
Consumer Protection and Environmental Health Service, Department
of Health, Education, and Welfare.
The objective of these programs is to determine on a national scale
the levels and trends of pesticides in the bodies of selected forms of
animals and in estuarine sediments. Fish and wildlife at or near the
top of the food chain are being sampled at each sampling location.
The species selected are not extremely sensitive to chemicals, are geo-
graphically well distributed, reasonably numerous, and easy to collect.
Residues in these organisms reflect residues in organisms at lower
levels of the food chain. The species chosen for monitoring of pesti-
cides in wildlife include the mallard or black duck, starling, and the
bald and golden eagles. The monitoring of pesticide levels in estu-
aries is done by the determination of pesticide levels in oysters and
clams. The upper estuarine sediment is also being sampled.
Pesticides in surface waters.—The program for the monitoring of
pesticides in surface waters is being carried out by the FWPCA and
Geological Survey of the U.S. Department of the Interior. The purpose
of this program is to provide information on the extent of pesticide
contamination of the Nation's water resources. Monitoring is cur-
rently confined to the surface waters in the major drainage rivers
of the United States. Sampling sites have been chosen according to
the following criteria: (1) Locations have been selected at or near
the mouths of major river drainages throughout the country; (2)
other sampling sites on river systems have been chosen when it is
believed that a reasonable measure of pesticide contamination cannot
be obtained by sampling at the mouth; (3) sites have been selected
at or near stream-gaging sites; (4) sites have been located where the
quality of river water is now being affected by the use of pesticides;
(5) if possible, the locations have been chosen where other kinds of
water quality data have been or are being collected; and (6) stations
have been located, if possible, at points from which historical data in
the form of carbon filter extracts are available. Fifty-three sampling
locations have been selected. In general, lakes and ground waters,
as well as ocean waters, which constitute the largest reservoir of
pesticides, are not being monitored.
Pesticides in soil.—Most of the soil monitoring program has been
carried out by the U.S. Department of Agriculture. Other aspects are
being conducted by the U.S. Department of Agriculture in cooperation
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with State and other Federal agencies. The objective of this program is
to determine levels of pesticide residues in soils of selected areas in the
United States and to detect any significant changes in these levels.
Soil monitoring sites were chosen where possible to coincide with
sampling sites of other agencies in the Federal pesticide monitoring
network so that soil data may be correlated with pesticide levels in
other environmental media. Soils in areas of high pesticide usage as
well as areas of low usage are being monitored.
Pesticides in air.-—An air monitoring network, eventually to include
pesticides, is being established by the National Air Pollution Control
Administration. Because of the considerable variability of pesticides
in air, their fallout and washout and the uncertan patterns of air
in air, their fallout and washout and the uncertain patterns of air
movement over the earth, the results of such monitoring will require
sophisticated interpretation.
Pesticides in people.—The monitoring of pesticides in people is
being carried out by the Division of Community Studies of the Food
and Drug Administration, CPEHS, HEW, at the Communicable Di-
sease Center in Atlanta. The purpose of this program is to determine
on a national scale the levels and trends of some of the commonly
used pesticides, both in the general population and in population seg-
ments where increased exposure levels are known or suspected. The
present monitoring program hopes to provide statistically and epi-
demiological^ sound information for use in the evaluation of the sig-
nificance of man's total exposure to pesticides. Such items as geo-
graphic area, conditions of exposure, type of pesticide, sex, and body
tissue samples are taken into account and evaluated. Two types of mon-
itoring studies are being conducted—a limited national survey of the
general population and an indepth study of selected communities in
high-use areas. Three population groups are being sampled: (1) Oc-
cupationally exposed workers (agricultural applicators, workers in
pesticide formulating plants, pest control operators, greenhouse work-
ers and aerial spray pilots); (2) individuals not occupationally ex-
posed but known to be repeatedly exposed (people living in agricul-
tural areas); and (3) the general urban population (people whose
exposures are largely limited to pesticide traces in food, water and air).
With long-term epidemiological data, it may be possible to distinguish
the effects of continuous low levels of exposure to pesticides on human
populations.
Analytical methods.—The accurate measurement of environmental
pesticide levels requires the continuing development of analytical meth-
ods sensitive enough to measure the low concentrations present. The
instrumentation, its correct operation and analysis of the results ob-
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tained by these techniques require highly trained and experienced per-
sonnel. Therefore, the proper monitoring of the pesticide levels in
such major environmntal components as food, air, and water is a
highly sophisticated operation.
Less complicated techniques are available but suffer from a lower
sensitivity. If insensitive procedures are adopted to save costs for
some monitoring operations, the use of a highly toxic compound could
be approved because of the poor method of analysis used, while the
use of another, less toxic compound is denied because a sensitive
method of analysis is available that indicates the presence of an in-
finitesmal amount. Clearly, in order to measure environmental pesti-
cide levels and evaluate their effects meaningfully, the most modern
and sensitive techniques available must be employed regardless of the
cost and complexity involved.
The measurement of pesticide residues in food is perhaps the most
advanced of all such techniques. The time required per analysis is rela-
tively low, the differentiation of the many different pesticide chemicals
may be reliably carried out, and the sensitivity is high, allowing the
accurate measurement of concentrations well below established toler-
ance limits. These techniques are also capable of determining ac-
curately a number of significant metabolic or alteration products.
Equipment of relatively high initial cost is required, however, and
highly qualified personnel must perform the analyses and interpret
the results.
The technique of measuring pesticide levels in air is not as highly
developed as those for food and water. The measurements are most
generally accomplished by passing a known volume of air through an
organic solvent contained in a gas scrubbing device. Ethylene glycol
is used most generally as the solvent. Care must be taken to obtain a
reagent blank free of compounds which would interfere with either
the electron capture or flame ionization gas liquid chromatography
systems. The presence in the atmosphere of so many compounds in
small concentrations requires that the analyst be certain that all the
peaks produced originated from the scrubbed air.
These compounds also present problems in identification and differ-
entiation amongst pesticides and other organic compounds, both syn-
thetic and naturally produced, that are found in the environment.
Competent analytical chemists capable of interpreting environmental
polution data must be employed.
Continuously operating monitoring systems are desirable because of
the large amount of air which may be sampled, but such systems re-
quire an inline calibration in order to obtain accurate measurements.
These are expensive to acquire and operate.
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The sensitivity of commonly used procedures is as low as 0.1 p.p.b,
and is limited by the volume of air sampled and the cleanup efficiency.
In general, the sensitivity of the methods now in use is not adequate
for the proper evaluation of pesticide levels in urban areas.
The two most commonly used procedures for extracting pesticide
residues from water are the batch method and the continuous extrac-
tion method. In the batch procedure, a definite volume of water,
usually 1 liter, is extracted with an organic solvent such as chloro-
form, hexane, etc. The continuous extraction method involves the
passage of a large volume of water through an extraction apparatus.
The carbon absorption method of extraction whereby pesticides are
absorbed onto activated carbon and then extracted has not proven to
be of sufficient sensitivity so is not used to any great extent at the
present time.
Using the parameters described in the Food and Drug Administra-
tion Pesticide Analytical Manual, as little as 1 p.p.b. heptachlor
epoxide, for example, can be measured by the batch technique. The
sensitivity of this method may be improved at the expense of system
stability. The sensitivity of the continuous extraction procedure is
limited by the volume of water extracted. Once again, trained analy-
tical chemists are required to interpret the data.
Analytical Needs.—In addition to refining existing methods and de-
veloping new methods where no suitable procedures are now available,
research leading to the development of automated instrumentation is
urgently needed. This report identifies the many sectors of the en-
vironment that are not now being adequately monitored, and pro-
poses extensive new investigations to identify epidemiological and
other hazards in the environment. The implementation of the recom-
mendations will require a considerably greater investment in pesti-
cide analysis. In the long run, the most economical approach to these
massive operations will have to be through automation.
Systems Analysis of Pesticides in the Environment
Guides to policy decisions for institutional management of pesti-
cides in the environment require the continuous assessment of (1) the
rates of input of the various pesticides into the environment; (2) their
various rates of degradation and formation of toxic degradation prod-
ucts and in turn the rates of degradation of these products; (3) the
mechanisms and rates of translocation of pesticides among the sev-
eral media of the environment; (4) and the storage and rates of accu-
mulation of pesticides in the various elements of the biosphere. The
concurrent examination of these changing rates and amounts consti-
tutes a "systems analysis".
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Such systems analysis research would have several objectives: It
would identify the data that need to be obtained to permit the analysis
to be made; it would permit an evaluation of the trend of accumula-
tion of pesticides in the environment and it would enable a cost-benefit
analysis to be made that could serve as a guide to pesticide utilization.
The first step would be to establish a conceptual systems analytic
framework for the evaluation of interregional and intraregional
movements of persistent pesticides as they are dispersed into the envi-
ronment, while the second step would be to develop an operational
regional model within the United States for the movement of persist-
ent pesticides, including the import and export of residues into and
out of the region. While the construction of a global model would be a
desirable goal, operationally the task is not a feasible one under rea-
sonable limitations of time, effort, money, and data availability. Em-
pirically derived inferences can be drawn from a regional model that
perhaps could limit the added value of a global model.
An essential part of the research, and possibly one of its most valu-
able contributions, would be an assessment of the adequacy of current
research and data collection activities upon which such models will be
built and upon which policy decisions must be made. The value of such
data and research can be measured only in terms of uses to which they
can be put.
The attached schematic diagram depicts a regional system for pesti-
cides movement among the air, biological, water and soil storage and
transport media. Also represented are additions of pesticides through
imports from other regions and direct application within the system
while losses are represented by export and decay. By constructing a
mathematical model of the regional system using established relation-
ships among its components and calibrating the model with the best
available estimates for model parameters, it is possible to assess the
impact on system response of alternative policies relating to rates and
methods of application. System response, measured by the amounts of
pesticides in any component at any time, can be translated into eco-
nomic, health, and ecological consequences, some of which have previ-
ously been established.
Because pesticides include a wide variety of chemicals which are
applied and dispersed by a number of processes and because persistent
pesticides are of primary concern in protecting environmental quality,
the research might initially be directed toward the behavior of the
persistent pesticides, the chlorinated hydrocarbons, with the other
pesticides being introduced after the model has been designed and
verified.
175
371-074 0—89 13
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IMPORT
DIRECT APPLICATION
EXPORT
Air borne
Sources
Biota
fl
ux
Water borne
Sources
assimi lotion
BIOTA
death
excretion
assimilation
I
WATER
adsorption
leeching
Air borne
Exports
Harvest and
biota flux
Water borne
Exports
DECAY
Flow diagram for regional system for pesticide movement in the environment.
176
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CHAPTER 3
Effect of Pesticides on Nontarget
Organisms Other Than Man
Contents
Page
Summary and conclusions 179
Introduction 186
Routes of exposure 192
The effects of pesticides 202
Alternative pest control practices and their potential danger
to nontarget organisms 215
Costs and value to society 220
Training and testing of pesticide users 221
Bibliography 222
177
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EFFECTS ON NONTARGET ORGANISMS OTHER
THAN MAN
Summary and conclusions
Man is an integral part of the living system, which includes about
200,000 species in the United States. Most of these are considered to
be essential to the well-being of man. Pesticides are now affecting indi-
viduals, populations, and communities of natural organisms. Some,
especially the persistent insecticidal chemicals such as DDT, have re-
duced the reproduction and survival of nontarget species.
Pesticides are dispersed via air, water, and the movements of organ-
isms. The most significant concentrations are found in and near the
areas of intensive use, but traces have been found in the Antarctic and
other areas far from application. Pesticides have reduced the popula-
tions of several wild species. Both extensive field data and the results
of excellent controlled experiments demonstrate that certain birds,
fishes, and insects are especially vulnerable. There are suggestions that
pesticides in the environment may adversely affect processes as funda-
mental to the biosphere as photosynthesis in the oceans.
However, the scarcity of information concerning the influences of
pesticides on natural populations prevents adequate assessment of
their total effects. Less than 1 percent of the species in the United
States have been studied in this connection, and very few of these
have been subjected to adequate observation. Present methods and pro-
grams for determining the influences of pesticides on nontarget organ-
isms are inadequate. Little data exists on the distribution, location, and
impact of various pest control chemicals in the natural living systems
of the world.
The general nature of the effects of pesticides on nontarget species
populations and communities can now be suggested. Although there
is usually greater similarity of reaction between closely related species,
each species reacts differently to specific pesticides. DDT, for example,
causes egg shell thinning in ducks and falcons, but not in pheasants
and quail. Pesticides from the air, water, and soil may be concentrated
in the bodies of organisms. The concentrating effect is frequently en-
hanced as one species feeds on another and passes the pesticide from
one link to another in the food chain. Hence, predators like some birds
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and fish may be exposed to levels several thousand times the concen-
tration in the physical environment. Some nontarget organisms can,
under highly selective pressure from pesticides, evolve resistance to
them. The surviving resistant individuals may pass extremely high
concentrations to their predators. In communities exposed to pesticides,
the total number of species is usually reduced and the stability of popu-
lations within the community is upset. Often, beneficial species are
unintentionally eliminated. Such a reduction in the number of species
is frequently followed by outbreaks or population explosions in some
of the surviving species, usually those in the lower parts of the food
chain. When a vital link low in the food chain is eliminated, many
predators and parasites higher in the food chain are often also
destroyed.
The Committee has reached the following conclusions:
1. Adequate methods should be developed and utilized for evalu-
ation of the hidden costs of the uses of pesticides.
Such evaluation is essential as part of the development of use-
ful estimates of all of the benefits and costs to society. Some
partial estimates of the direct benefits are available and useful.
Adequate data are not available on such indirect costs as losses
of useful fish and wildlife, damage to other species, and any
esthetic effects. These are required to guide rational decisions
on the proper uses and control of pesticides so that the net gains
will be as great as possible while the net losses are minimal.
2. Persistent chlorinated hydrocarbons which have a broad spec-
trum of biological effects, including DDT, DDD, aldrin, chlordane,
dieldrin, endrin, heptachlor, and toxaphene, should be progressively
removed from general use over the next 2 years.
These pesticides are causing serious damage to certain birds,
fish, and other nontarget species among world populations.
Some of these species are useful to man for food or recreation,
some are essential to the biological systems of which he is a part,
and some merit special protection because they are already
endangered.
These pesticides have value in specific circumstances, and
we suggest that they be used only under license and with spe-
cial permits. The system for assuring this careful use should
be established as the unrestricted use of these materials is
phased out over the 2-year period.
3. The release of biocidal materials into the environment should
be drastically reduced.
In addition to restriction of the use of hazardous pesticides,
many techniques can be applied which will minimize the re-
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lease of pest control chemicals. In industry, improved chem-
ical and engineering processes could reduce the quantity of
contaminated wash water; more effective methods can be
developed for disposal of unused stocks and residues of pesti-
cides; and improved surveillance of effluents would be de-
sirable. For home use, improved materials and methods of
application can be created and employed with greater discre-
tion on the part of the individuals involved. For large-scale
applications, conversion to integrated methods of pest control,
care in the selection and application of specific chemicals, and
preference for short-lived pesticides would reduce release to
the environment.
These efforts, combined with increased research and educa-
tion, would slowly but effectively reduce the damage to non-
target species.
4. The U. S. Department of Health, Education, and Welfare
or another Federal agency should negotiate a contract with a suitable
national professional organization to develop a system, complete
with standards of training, testing, and enforcement, for the effective
restriction of use of selected pesticides known to be especially haz-
ardous to man or to elements of the environment.
To achieve an adequate and prompt further reduction in
the use of certain pesticides and still permit their use where
no adequate substitute is acceptable, there must be a system
of regulation based upon State or local authority but using
uniform national standards. This system should provide for
use of the selected pesticides only by or under the immediate
supervision of a licensed operator meeting certain standards
of training, competence, and ethics.
5. Educational efforts relating to the proper and improper usages
of pesticides should be improved and expanded.
The most important element in the wise use of pesticides
is the individual person who selects the chemical to be used and
decides upon the methods of application. Suggestions have
been provided elsewhere for the proper training of all large-
scale applicators. It is equally important that homeowners,
gardeners, students, legislators, civic officials, and others receive
adequate and correct information and develop proper atti-
tudes. Such education could contribute greatly to wise use of
pesticides, and also to rational response to governmental efforts
to protect public health and welfare while gaining as much
advantage as possible from pest control methods.
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6. All pertinent Federal and State agencies should review and
improve policies and practices of pesticide use.
The beneficial uses of pesticides have been accompanied by
a wide variety of policies and practices which have sometimes
been wasteful, unnecessarily destructive, or ineffective. We
offer the following suggestions to be included among the guide-
lines for wise use of pesticides:
a. Pesticides should be applied only when there is evidence
that pest densities will reach a significant damage threshold.
b. Effective pest control does not usually require eradication
of the pest species, and should be directed toward optimal
management of pest densities.
c. Support for research and demonstrations should be pro-
vided to projects based on the systems approach to pest manage-
ment and control.
d. Diversity of species is biologically desirable since it con-
tributes to the stability and efficiency of life systems.
e. No species should be eradicated except as a carefully se-
lected pest and when compensating human gains are ecologically
sound and clearly established.
f. Special care must be taken to prevent any damage to the
species and mechanisms which are of fundamental importance
to biological systems. For example, oceanic photoplankton pro-
duces most of the oxygen necessary for the earth's biological
system.
g. Requirements for food quality should not be so high as to
require excessive use of pesticides. Customer preference, and
regulatory requirements, for unblemished fruit and vegetables
and the complete absence of insect parts have encouraged heavy
use of pesticides.
h. New pesticides should be given interim approval which
permits contained use in limited but typical circumstances
prior to general approval. The pattern of careful progressive
risks would encourage new developments without endangering
the public interest.
i. Effective incentives should be established to encourage the
development of improved pest control techniques. The cost of
entering a new product or testing a different control technique is
high. Since effects on the national welfare are involved, proper
governmental encouragement of private industrial efforts may
be appropriate.
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7. Registration requirements should be strengthened and rede-
signed to permit initial provisional approval, then general use ap-
proval, and to require periodic review and re-registration of materials.
Registration of pesticides offers the most important oppor-
tunity for estimating potential benefits and costs in advance
of wide usage. In addition to present registration application
information, useful estimates should be provided of the per-
sistence of the pesticide, on the breadth of its biological impact,
and on its fate. These will disclose the nature and possible mag-
nitude of the nontarget effects. If approval is appropriate, we
suggest that it be for a short-term period and for use under
defined circumstances where risks are confined, and that general
use be considered after such field experience. Since some of the
significant effects in nontarget species are subtle, sublethal, and
difficult to detect, we recommend that all pesticides be subject
to periodic review and approval.
8. All commercial applications and other large-scale applications
of pesticides should be performed under the supervision of competent
trained persons.
The complex responsibilities of pesticide application involve
both achievement of the greatest possible benefit and maximum
prevention of damage. These require considerable knowledge of
the management of crops, the biology of desirable and unde-
sirable species, the effects of weather, and the effects of biocide
in the ecosystems. They also require application of professional
judgment and use of professional standards of conduct and
responsibility. We suggest that all such applicators should be
properly trained, required to demonstrate their competence, and
awarded evidence of their ability. Incentives in the forms of
salary and recognition will be needed to encourage such pro-
fessional training.
Training programs for pest management specialists of all
types, including applicators, should include the concepts of sys-
tems approaches to pest control and emphasize the relationships
between pest management activities and the total biological
community affected.
Since new information is emerging rapidly in pest manage-
ment, refresher courses for county agricultural agents, appli-
cators and others involved in the uses of pesticides and other
eontrol techniques would be of special value.
9. The production of additional information and comprehension
should be encouraged and supported on many aspects of pesticide use
and effects.
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Experience with pesticides has revealed many serious gaps in
available knowledge. Research is urgently needed on many gen-
eral and specific problems. The following problems are all re-
lated to nontarget effects of pesticides, and many of them are
also pertinent to other areas of pesticide use, to successful man-
agement of animals and plants, and to fundamental science.
a. What are the acute effects of the common pesticides when
used on the many species of wildlife and other organisms which
may be exposed to them ?
b. What are the effects of indirect and chronic exposure?
c. What is the nature and magnitude of the effects of insecti-
cides on beneficial insects and other species?
d. What are the normal patterns and variations in natural
biotic communities, as baselines for understanding future pesti-
cide pollution effects?
e. What mechanisms exert natural control on various pest
populations?
f. How can we best estimate pest populations and predict
their trends?
g. What are the full potentials and realistic limitations of the
pest control methods which are suggested as alternatives to
chemical pesticides, including predators, parasites, pathogens,
cultural control, sterilization, attractants, repellants, genetic
manipulation, and integrated approaches?
h. What improvements are possible for pesticide packaging
and disposal (including degradable containers) to minimize
threats to nontarget species?
10. A vigorous specific program should be created to bring the 100
most serious insect pest species of the United States under optimal
control.
These require about 80 percent of the insecticides now in use.
Dramatic focusing of attention on the "100 worst" could lead to
rapid improvement in the species-specific insecticides, bio-
logical control methods, or integrated control programs.
11. The responsibilities of the several Federal agencies involved
in pesticide regulation and control must be more clearly defined and
certain specific activities should be improved or initiated by appro-
priate agencies.
Procedures and patterns for the regulation and control of
pesticide use have emerged during the last 30 years in response
to changes in law, evolving practices in agriculture, production
of new chemical materials, changing public concern with health
effects and nontarget damage, emerging scientific comprehen-
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sion of benefits and costs, and other unstructured events. Both
benefits and costs are now so large as to merit the national allo-
cation of responsibilities. We suggest careful review and
reassignment, by law if necessary, of the proper role of—
a. The Department of Interior, charged with protection and
enhancement of nonagricultural resources and with water
quality control.
b. The Department of Agriculture, charged with assisting in
the maximum production of food, fibers, and other culturable
crops in ways which are not detrimental to other interests.
c. The Department of Health, Education, and Welfare,
charged with protection and improvement of human health and
welfare.
d. The National Science Foundation, responsible for im-
proved comprehension of fundamental processes and assisting
in their application for human benefit.
e. The Environmental Quality Council, Federal Committee
on Pest Control, and other coordinating agencies.
Other agencies are, of course, involved as users of pesticides
and in other functions. Those listed above, however, appear
to comprise the areas of primary attention. In addition to pres-
ent programs and activities related to pesticides, we suggest
the following services for new or additional emphasis:
a. A taxonomic and identification service should be estab-
lished to provide increased knowledge and reference standards
for biological investigations related to all fields of pest control.
b. Broader monitoring should be undertaken of the types
and quantities of pesticide transmitted by various means and
reaching nontarget species. Bioaccumulators like oysters and
other molluscs can be unusually useful as indicators, and the
levels of concentrations in predatory species are of special
importance.
c. Early indications of undesirable effects must be detected
effectively and followed by appropriate action. When the early
warning system suggests a potential pollution hazard in the
environment, the acquisition of additional pertinent informa-
tion by the scientific community should be supported.
d. Multidisciplinary investigations of alternative control
techniques should be carried out whenever present control meth-
ods are shown to contain potential hazards.
e. A single agency should assume the responsibility for
assimilating information on the effects of pesticides on nontar-
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get species and transmitting it to appropriate regulatory and
educational centers.
f. Measurable predictors of potential hazards from pesti-
cide use should be agreed upon and might be made the basis
of a handicap tax to be applied to each pesticide in proportion
to its pollution hazard.
Introduction
The earth supports a complex system of living organisms of which
man is an integral part. The system also involves the chemical and
physical environments of the earth's crust, the oceans, the atmos-
phere, and the interfaces between them. In these environments, mil-
lions of kinds of organisms have evolved, each species with a specific
set of requirements.
Certain basic ecological principles are well established. Only the
plants can synthesize organic compounds, through photosynthesis.
Some animals feed on plants, some on other animals, and some on
both. Bacteria and a few other organisms participate in the break-
down processes which return the chemical elements to simple forms
which can be reused and recycled. This master cycling is accompa-
nied by lesser cycling of specific elements and compounds in ways
which are only partially understood. Events on land, in the sea, and
in the air can affect the processes and rates over a very wide area
of the earth, since this is a single global life system.
Only in recent centuries has the human species had more than
trivial impact on biological events in the world. In the century since
the industrial revolution, man has brought large areas under con-
trol, changed populations and, eventually, collected and used such
large quantities of some materials as to modify parts of the bio-
sphere. Improved agricultural yields and grave pollution problems
are both aspects of these accomplishments.
THE FOOD NETWORK
For the present discussion, the significant questions are whether
or not man's uses of chemicals to kill or control pest species at spe-
cific sites has caused serious damage to nontarget species, popula-
tions, and processes in the world life system.
Solar energy captured by photosynthesis is available for biological
use by herbivores, then (in quantities which rapidly decline) to omni-
vores, carnivores, supercarnivores, and organisms of decay. This
sequence is easily stated, but rarely occurs in nature. There, the energy
transfer process is more accurately described as a network, since
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different stages of each species play differing roles and since an
enormous number of species are involved.
When a persisting chemical compound is made available to this
biological network, its movements and biological effects may involve
many species, locations, and degrees of effect. So it is with some of
the persistent pesticides. Among the benefits the world has received
from the use of DDT, high value should be placed on the increased
knowledge and appreciation which has been gained of the global
unity of the biological network and, therefore, of the global effects
of local chemical usages.
Such chemicals are directed toward a pest species. Release places
the chemical on or in the target and, invariably, on or in other species
and parts of the environment. The chemical begins its movement
through the ecosystem. We cannot quantitatively describe the trans-
port of DDT or other chemicals, except for a short period in a river
or pond, 'but evidence is sufficient to prove the constant movement of
part of the material into and through living organisms. There, the
chain effect of feeding patterns may create increasing concentrations
in subsequent food levels. In general terms, only about 10 percent of
the energy in one trophic level will be transferred to the next level,
and the rest will be used for respiration or released as wastes. Chemi-
cals whidh are preferentially absorbed into living organisms and
stored for extended period, as are DDT and its derivatives, may, there-
fore, be concentrated greatly up the food chain. At any point, the
chemical may reach a species which is susceptible to it and damage
will result. The nature of the food web and the distribution of a pesti-
cide are partially illustrated in figure X, from the article in The Scien-
tific Americam, 'by A. M. Woodwell.
If release of sudh a chemical is terminated, the quantity in the eco-
system will gradually decline in accordance with the rate of natural
conversion of the substances to compounds or elements which do not
have the same effects. This decline in biological organisms will occur
over a long period, related to the length of life of various involved
species and many other factors. Eventually, the amount of chemical
compound will be insignificant in the ecosystem.
SPECIES ANT) SPECIFICITY
Since the appearance of the first organism on earth some 4,000 mil-
lion years ago, about 99 percent of all species have become extinct.
Gradually, species after species has been replaced by those better
adapted to the new environmental conditions which also have been
continually changing. The evolutionary process and the development
of new species take thousands of years; a slow process and especially
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BILlFtSH IJJ7
MUO SNAIL\M
FLUKE 1JI
PLANKTON .04
CLAM «
GULLS
I, m
MINNOW .M
CHPFERA JO
KINGFISHER
REDWING BLACKBJRO
The food web is a complex network through which energy passes from plants to
herbivores and on to carnivores within a biological community. This web show-
ing some of the plants and animals in a Long Island, estuary and along the
nearby shore was developed by Dermis Puleston of the Brookhaven National
Laboratory. Numbers indicate residues of DDT and its derivatives (in parts
per million, wet weight, whole-body basis) found in the course of a study made
by the author with Charles F. Wurster, Jr., and Peter A. Issaeson.
Permission to use granted by The Scientific American. From Woodwell, O. M.:
Toxic Substances and Ecological Cycles. The Scientific American. 216: Vol. 216,
March 1967.
slow relative to man's life span. Today an estimated 2 million plant
and animal species exist on earth. Most of these species are found in
the favoralble tropical regions with fewer species existing in the tem-
perate regions and only a few able to endure the harsh polar climates.
No one knows how many of these estimated 2 million species are
necessary in man's environment for his survival and welfare. Cer-
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tainly he cannot survive with only his crop plants and domesticated
animals. Most natural species interact in maintaining1 a functional
life system. Understanding the biology of the life system is most diffi-
cult because of vast numbers of species and the complexity of their
interactions. Current knowledge suggests great caution in evaluating
the worth of a particular species.
There is a pattern of basic characteristics common to all organisms,
including a genetic code, a reproductive system and a structure pri-
marily dependent upon carbon, oxygen, hydrogen, and nitrogen. These
characteristics plus the basic requirements of life (energy, matter, and
a suitable environment) form a set of similarities which are applicable
to all forms of life.
The study of plant and animal classification has revealed both simi-
larities and specificity in organisms. Each species is a unique biochem-
ical entity; therefore, species react to each pesticide in a different
manner.
The ancestral system of life and the various lineages provide a
recognized organization and pattern for life in general and species
groups in particular. The more similar the species group, the more
likely its members will respond to environmental factors in a like
manner.
PESTICIDES AND TOXICITY
Approximately 900 chemicals are registered with the USDA-PED
as pesticides for |