SEPA
United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Cincinnati OH 45268
EPA-600/1-78-013
July 1978
Research and Development
Reviews of the
Environmental
Effects of
Pollutants:
I. Mirex and Kepone
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS RE-
SEARCH series. This series describes projects and studies relating to the toler-
ances of man for unhealthful substances or conditions. This work is generally
assessed from a medical viewpoint, including physiological or psychological
studies. In addition to toxicology and other medical specialities, study areas in-
clude biomedical instrumentation and health research techniques utilizing ani-
mals — but always with intended application to human health measures.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/1-78-013
July 1978
REVIEWS OF THE ENVIRONMENTAL EFFECTS OF POLLUTANTS:
I. MIREX AND KEPONE
by
Mary Arme Bell, Robert A. Ewlng and Garson A. Lutz
Battelle
Columbus Laboratories
Columbus, Ohio 43201
Reviewer and Assessment Chapter Author
Earl 6. Alley
Mississippi State Chemical Laboratory
Mississippi State, Mississippi 37962
Contract No. 68-03-2608
Date Published: October 1979
Project Officer
Jerry F. Stara
Office of Program Operations
Health Effects Research Laboratory
Cincinnati, Ohio 45268
HEALTH EFFECTS RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Health Effects Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
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FDREW3RD
A vast amount of published material is acx^jmulating as numerous research
investigations are conducted to develop a data base on the adverse effects
of environmental pollution. As this information is amassed, it becomes
continually more critical to focus on pertinent, well-designed studies.
Research data must be summarized and interpreted in order to adequately
evaluate the potential hazards of these substances to ecosystems and ulti-
mately to public health.
The series of documents entitled "Reviews of the Enviornmental Effects
of Pollutants" (REEPs) represents an extensive compilation of relevant
research and forms an up-to-date compendium of the environmental effect data
on selected pollutants.
The Review of the Environmental Effects of Mirex and Kepone includes
information on the chemical and physical properties of both compounds;
pertinent analytical techniques; transport processes to the environment and
subsequent distribution and deposition; impact on microorganisms, plants,
and wildlife; toxicologic data in experimental animals including metabolism,
toxicity, mutagenicity, teratogenicity and carcinogenicity; and an assess-
ment of their health effects in man. The volume of factual information
presented on Mirex and Kepone in this document is summarized and interpreted
in the final chapter "Environmental Assessment", which presents an overall
evaluation of the potential hazard resulting from present concentrations of
mirex and kepone in the environment. This final chapter represents a major
contribution by Dr. Earl G. Alley from Mississippi State University.
The REEPS are intended to serve various technical and administrative
personnel within the Agency in the decision-making processes; i.e. in
the development of criteria documents and environmental standards, and
for other regulatory actions.*
* The breadth of these documents makes them a useful resource
for public health personnel, environmental specialists, and
control officers. Upon request these documents will be made
available to any interested individuals or firms, both in and
out of the Government. Depending on the supply, you can
obtain the document directly by writing to:
U.S. EPA
Environmental Criteria and Assessment Office
26 W. St. Clair Street
Cincinnati, Ohio 45268
Stara
Director
Environmental Criteria and
Assessment Office
iii
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PREFACE
Mirex and Kepone are two members of the family of organochlorine
pesticides whose environmental effects have, until recently, been
relatively ignored when compared with such compounds as DDT, chlordane,
aldrin, and dieldrin. However, mirex and Kepone are two of the most
stable and persistent members of this family. Recent events have made it
increasingly apparent that the environmental effects of these compounds
needed to be appraised.
Both mirex and Kepone are relatively recently used compounds. They
have been manufactured commercially for only about 25 years; each was
basically a one company product, and each had only limited, specialized
pesticidal use. However, their environmental impacts have not been
inconsequential. Millions of acres in the southeastern United States have
been treated with mirex for control of the imported fire ant, and the
extent of inadvertent contamination with Kepone from the Life Sciences
Products Company is well known.
Unfortunately, there have been few investigations of their health
and environmental effects, and much of the data on these substances are
proprietary in nature. The present document has attempted to consider all
of the open literature and some of the internal reports made available to
the authors. However, because of the lack of extensive research, the
anticipation and assessment of all potential environmental effects is not
possible. The use of these pesticides has been banned; therefore, the
present environmental burden should decrease as a result of their
biodegradation, even through they are relatively stable and will be
present in the environment for a long time.
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ABSTRACT
The objective of this research program was to assemble and analyze
the publicly-available information on the environmental effects of the
two organochlorine pesticides, mirex (C.QCl-p) and its ketone analog,
Kepone (C1QC112). The data base on these compounds is limited, especially
with respect to Kepone, on which almost no environmental research was
conducted prior to the Life Science's Products Company incident. Both of
these compounds are non-volatile, have very low water solubilities, are
chemically and thermally very stable, and are quite resistant to
biodegradation, thus, existing environmental residues can be expected to
persist for years.
Neither mirex nor Kepone appreciably affects microorganisms or
plants in usual environmental concentrations. Mirex does not appear to
present a serious acute toxicity problem to non-target terrestrial
invertebrates as a result of fire ant control efforts. Both mirex and
Kepone produce adverse reproductive effects in numerous species. Mirex
has been shown to induce liver tumors in mice and rats and is judged to
have potential carcinogenicity, and carcinogenic properties of Kepone
have been documented in mice and rats.
Both mirex and Kepone are lipid-soluble and accumulate in fatty
tissues, from which the rate of excretion is slow. Mirex has been
detected in adipose tissues of humans and in beef fat from cattle in
areas aerially treated for fire ant control, but there are few definitive
data on its effects on humans, and exposures appear to have been minimal.
Exposures of humans to Kepone in roach and ant traps appears also to have
been minimal. Excessive exposures did result from the inadequate control
of Kepone during its manufacture at LSPC. No practical scheme for the
removal or neutralization of the Kepone contained in James River
sediments downstream of this plant have yet been devised, and this
environmental inventory is likely to pose a problem for many years.
This report was submitted in fulfillment of Contract No. 68-03-2608
by Battelle's Columbus Laboratories under the sponsorship of the U.S.
Environmental Protection Agency. This report covers the period from April
1976 to August 31, 1978, and work was completed as of September 30, 1978.
vii
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CONTENTS
Foreword
Preface v
Abstract vii
List of Figures xiii
List of Tables . xv
Acknowledgements xix
Sections
1.0 General Summary 1
1.1 Technology of Mirex and Kepone 2
1.2 Effects on Microorganisms 3
1.3 Effects on Plants 3
1.4 Effects on Biota 3
1.5 Effects on Humans 5
1.6 Environmental Distribution and Transformation 6
2.0 Technology of Mirex and Kepone 9
2.1 Summary 9
2.2 Structure and Preparation 10
2.3 Characterization of Mirex and Kepone 13
2.3.1 Physical and Chemical Properties 13
2.3.1.1 Mirex 13
2.3.1.2 Kepone 14
2.3.2 Chemical and Thermal Stability 15
2.3.2.1 Mirex 15
2.3.2.2 Kepone 23
2.4 Analysis 25
2.4.1 Methods of Analysis 25
2.4.1.1 Gas-Liquid Chromatography 26
2.4.1.2 Thin-Layer Chromatography 30
2.4.1.3 Mass Spectrometry 30
2.4.2 Analytical Considerations 31
ix
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CONTENTS (Continued)
2.5 Manufacture and Use 31
2.5.1 Mirex 31
2.5.1.1 Manufacture 31
2.5.1.2 Use 34
2.5.2 Kepone 39
2.5.2.1 Manufacture 39
2.5.2.2 Use 41
2.6 References 43
3.0 Effects on Microorganisms 49
3.1 Summary 50
3.2 Estuarine Microorganisms 51
3.3 Soil Microorganisms 51
3.3.1 Mirex 51
3.3.2 Kepone 52
3.4 Sludge Microorganisms 52
3.4.1 Mirex 54
3.4.2 Kepone 55
3.5 References 57
4.0 Effects on Plants 57
4.1 Summary 57
4.2 Field and Pasture Crops 57
4.3 Metabolism 58
4.4 References 62
5.0 Effects on Biota 63
5.1 Summary 63
5.2 Aquatic Biota 67
5.2.1 Mirex 67
5.2.1.1 Algae and Phytoplankton 67
5.2.1.2 Aquatic Invertebrates 68
5.2.1.3 Fish 79
5.2.1.4 Food Chains 83
5.2.2 Kepone 86
5.2.2.1 Algae and Phytoplankton 86
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CONTENTS (Continued)
5.2.2.2 Aquatic Invertebrates 86
5.2.2.3 Fish 89
5.2.2.4 Food Chains 91
5.3 Terrestrial Biota 92
5.3.1 Terrestrial Invertebrates 92
5.3.1.1 Mirex 92
5.3.1.2 Kepone 94
5.3.2 Amphibians and Reptiles 95
5.3.3 Birds 95
5.3.3.1 Mirex 95
5.3.3.2 Kepone 101
5.3.4 Mammals 104
5.3.4.1 Comparative Acute Toxicity of Mirex
and Kepone 104
5.3.4.2 Mirex 104
5.3.4.3 Kepone 128
5.4 References 143
6.0 Effects on Humans 151
6.1 Summary 151
6.2 Sources of Potential Exposure to Mirex 154
6.2.1 Mirex in Human Tissues 155
6.3 Sources of Potential Exposure to Kepone 156
6.3*1 Kepone in Human Tissues and Fluids 157
6.4 Acute Exposure to Kepone 158
6.4.1 Epidemiology of Kepone Poisoning 158
6.4.2 Clinical Findings in LSPC Workers 161
6.4.2.1 Blood Levels 163
6.4.2.2 Tissue Levels 163
6.4.2.3 Metabolism of Kepone 165
6.4.2.4 Effects 165
6.4.2.5 Treatment 166
6.4.3 Risk Assessment of Carcinogenic Effects 168
6.4.4 Subacute Exposure to Kepone 170
6.5 Residues in Foods 171
6.5.1 Mirex 171
6.5.2 Kepone 178
6.6 References 184
7.0 Environmental Distribution and Transformation 188
xi
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CONTENTS (Continued)
7.1 Summary 188
7.2 Distribution of Mirex in the Physical Environment. ... 189
7.2.1 Entry Into the Environment 189
7.2.2 Soil 190
7.2.2.1 Mobility and Persistence in Soil .... 191
7.2.3 Water and Sediments 193
7.2.3.1 Mobility and Persistence in Water and
Sediments 197
7.2.4 Air 200
7.3 Distribution of Kepone in the Environment 200
7.3.1 Entry Into the Environment 200
7.3.2 Soil 201
7.3.2.1 Mobility and Persistence in Soil .... 202
7.3.3 Water and Sediments 202
7.3.3.1 Mobility and Persistence in Water and
Sediments 205
7.3.4 Air 209
7.4 Distribution of Mirex and Kepone in the Biological
Environment 209
7.4.1 Accumulation in Non-Target Organisms 209
7.5 References 214
8.0 Environmental Assessment 218
8.1 Environmental Assessment - Mirex .... 218
8.1.1 Uses 218
8.1.2 Analysis 219
8.1.3 Environmental Contamination 219
8.1.4 Bioaccumulation 220
8.1.5 Nonhuman Toxicology 221
8.1.6 Effects on Human Health 223
8.1.7 Regulations 224
8.2 Environmental Assessment - Kepone 224
8.2.1 Uses 225
8.2.2 Analysis 225
8.2.3 Environmental Contamination 225
8.2.4 Bioaccumulation 226
8.2.5 Nonhuman Toxicology 227
8.2.6 Effects on Human Health 228
8.2.7 Regulations 228
8.3 References 229
xii
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FIGURES
2.1 Synthesis of mirex and Kepone 11
2.2 Thermal destruction plot for mirex 17
2.3 Thermal destruction plot for Kepone 24
2.4 Effect of residence time at 433 C on thermal destruction
of Kepone 25
2.5 Generalized analytical procedure flow diagram for mirex
in biological samples 28
2.6 Fire ant distribution, 1976 35
5.1 Comparison of cell densities at three nutrient concentrations
of untreated cultures and those grown in 0.2 ppb mirex . . 69
5.2 Uptake of mirex by algal population after seven days
exposure 70
14
5.3 Plasma levels of mirex after administration of C-mirex
to female rhesus monkeys 111
14
5.4 Cumulative urinary excretion of C after administration of
labeled mirex to female rhesus monkeys 111
5.5 Scheme for four-compartment, open-system mammilary models. . 115
5.6 Plasma levels of mirex vs time in monkeys after iv
injection of C-mirex 116
5.7 Cumulative fecal and urinary excretion ofj.mirex vs
time in monkeys after iv injection of C-mirex. 117
5.8 Calculated amount of mirex in various compartments vs
time in monkey no. 2 after a single iv injection of
C-mirex 118
5.9 Dixon plot of effect of mirex and Kepone on LDH activity . .121
5.10 Comparison of incidence of hepatocellular carcinoma in
mice and rats following treatment with Kepone at two
levels 141
xiii
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FIGURES (Continued)
6.1 Stimulatory effect of cholestryamine on the rate of
excretion of chlordecone in the stool 168
7.1 Mirex concentrations in Lake Ontario sediments 198
7.2 James River sediment Kepone concentrations in the
vicinity of Hopewell, Virginia 206
7.3 James River sediment Kepone concentrations from
Richmond, Virginia, to the mouth of the Chickahominy
River 207
7.4 James River sediment Kepone concentrations from
Williamsburg, Virginia, to Newport News 208
xiv
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TABLES
2.1 Compounds and Concentrations Found in Recovered Soil
and Bait Samples 21
2.2 UV and r Irradiation Products of Mirex 22
2.3 Sales of CWCI^, 1959-1975 33
2.4 Aggregate Areas Treated with Mirex Under Federal-State
Cooperative Program, FY 1962-1973 37
2.5 Receipts of Technical Kepone at Baltimore, Maryland,
Formulating Plant of Allied Cheical Corporation 42
3.1 Ratio of Radioactivity in Mirex and metabolite Zones
on Thin-Layer Silica Gel Plates 53
4.1 Concentrations of Mirex Residues in Different Parts of
4-Week-Old Crop Seedlings Grown in Loamy Sand and
Experimental Field Soil 60
4.2 Uptake of Mirex by Pea and Bean Plants 61
5.1 Mirex Residues in Blue Crabs and Their Larvae 73
5.1 Percent Mortality of P_^ Blandingi and P^ Hayi Following
Initial Exposure to Various Concentrations of Mirex. ... 75
5.3 Concentration of Mirex Accumulated by Striped Mullet
Exposed to Mirex in Water for 96 Hours in a Continuous
Flow Bioassay System 82
5.4 Accumulation of Kepone by Selected Aquatic Invertebrate
Species 87
5.5 Bloconcentration Factors for Selected Species that Were
Exposed to Measured Concentrations of Kepone in Water . . 93
5.6 Representative Oral LD,-0 Values for Mirex 96
5.7 Dietary Toxicities of Mirex Tested in 5-Day Diets of Young
Bobwhites, Japanese Quail, Ring-Necked Pheasants, and
Mallards 97
xv
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TABLES (Continued)
14
5.8 C Residues^in the Tissues of Japanese Quail Fed 30 ppm
of C-Mirex in the Diet 98
5.9 Mirex Content of Herring Gull Eggs Collected in the Great
Lakes in 1974 and 1975 102
5.10 The Acute Oral and Dermal Toxicity of Kepone and Mirex
in Rats 105
5.11 Radioactive Residues in the Tissues of Rats Fed 30 ppm
Mirex in the Diet 107
14
5.12 Distribution of C-Mirex Administered Orally to Rats. ... 109
5.13 Tissue Content of Radioactivity as Mirex in Female Rhesus
Monkeys After Administration of a Single Dose of
C-Mirex 112
5.14 Percent of Administered Mirex Found in Various Tissues
of Autopsy of Female Rhesus Monkeys 113
5.15 Parameters for Mirex Model in Monkeys 115
5.16 Relative Risk for Development of Tumors Among Mice
Treated with Mirex When Compared with Controls 126
5.17 Tumors Among Mice Receiving Mirex 127
5.18 Acute Oral Toxicity of Kepone to Various Mammals 128
5.19 Summary of Kepone Mortality Studies with
the Laboratory Mouse 130
5.20 Liver Weight as a Percentage of Body Weight in Kepone-Fed
and Control Mice 131
5.21 Residues of Kepone in Mouse Organs at a Dietary Level
of 40 ppm 132
5.22 Residues of Kepone in Mouse Organs After Withdrawal of
40 ppm Diet 133
xvi
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TABLES (Continued)
5.23 Reproduction Data for 100 Days of Kepone-Fed and
Control Mice 138
6.1 Summary List of Toxic Effects of Kepone in Humans and
Animals 159
6.2 Kepone Poisoning Attack Rates by Job Category 160
6.3 Blood Kepone Levels by Groups of Exposed Persons 162
6.4 Kepone Levels in Various Tissues of Kepone Workers .... 164
6.5 Tissue Distribution of Kepone in Hospitalized Workers. . . 167
6.6 Pesticide Residues in Lake Ontario Fish Collected in
August and September, 1975 174
6.7 Mirex Data for Fish From Lake Ontario and Tributaries,
as of September 22, 1976 176
6.8 Mirex Findings by Geographic Areas Within South Atlantic
and Gulf Coast States 179
7.1 Mirex Residues in Soil Collected in Mississippi (1972)
and Louisiana (1971-72) 192
7.2 Mirex Residues in Filtered Water Collected
in Mississippi (1972) 195
7.3 Mirex Residues in Sediment Collected in Mississippi
(1972) and Louisiana (1971-72) 196
7.4 Mirex in Lake Ontario Sediments - 1968 199
7.5 Summarized Sediment and Water Analyses, January, 1976. . . 204
7.6 Results of Analysis of Three Cores from Windmill Point
Shoal Taken Before Dredging 204
7.7 Mirex Residues in Human Food Chain from Pretreatment to
1 Year After Single Mirex Application 211
7.8 Accumulation of Mirex in Biota 212
xvii
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ACKNOWLEDGEMENTS
Other Battelle-Columbus staff members contributed specialized
expertise in the preparation of this document including Ms. Verna 0.
Holoman, Ms. Mary Ann Eischen, and Mr. David A. Savitz. Mrs. Julia G.
Jefferis was particularly helpful in the conduct of the literature search.
The authors wish especially to acknowledge thhe valuable
contribution of Dr. Earl G. Alley of Mississippi State University for his
overall summary and environmental assessment of the final chapter.
We also wish to express our appreciation for the cooperation and
support received from EPA staff of the Health Effects Research Laboratory
during the preparation of this document. Unflagging support and
encouragement was provided throughout the program by the project officer,
Dr. Jerry F. Stara. He was ably assisted by Donna J. Sivulka initially
and later by Bonita M. Smith and Karen L. Blackburn. The support of Dr.
John R. Garner, Director of HERL was much appreciated.
xix
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1.0 EXECUTIVE SUMMARY
R*
Mirex and Kepone are two of the more recent additions to the large
family of organochlorine compounds used to combat insect pests. They are
chemically quite similar. Mirex is an extremely stable and persistent
compound containing only carbon and chlorine atoms, with the formula
C10C1]2" KeP°ne has an analogous ketone structure, with two of the
chlorine atoms replaced with an oxygen atom, C.-Cl^O. Mirex has been
widely used in the southeastern United States for control of the imported
fire ant, via aerial broadcasting of a mirex - containing bait. In these
areas mirex has been detected in a number of non-target organisms,
including man. Recent improvements in bait formulation appear to make
effective control possible at application rates of below 2.5 g/ha (1
g/ac) of active ingredient.
The estimated quantity of mirex applied for fire ant control between
1959 and 1977 is approximately 275,000 kg (600,000 Ib). Recently
promulgated EPA regulations permit aerial application only through
December 31 > 1977. The future use of mirex for control of the imported
fire ant in the U.S. is uncertain.
Unlike mirex, Kepone has not been used widely in the U.S. Its
principal domestic use is in ant and roach traps around homes and
buildings. Most Kepone produced in the U.S. was exported to other
countries for use against the banana root borer, and for conversion into
other insecticides. Accordingly, the environmental effects of Kepone were
little studied prior to the discovery of gross discharges of Kepone from
the Life Sciences Products Company plant at Hopewell, Virginia, where it
was manufactured. Severe contamination of the James River and its biota
resulted, for which a solution has not yet been found.
After the discovery of the gross Kepone contamination from the Life
Sciences Products Company, the plant was shut down and manufacture of
Kepone terminated in July, 1975. Kepone is no longer being manufactured
in the United States. Total production of Kepone was approximately
1,600,000 kg (3,500,000 Ib) of which 90 to 95 percent appears to have
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1.1 TECHNOLOGY OF MIREX AND KEPONE
Both mirex and Kepone are produced from hexachlorocyclopentadiene.
Both are moderately soluble in organic solvents but almost insoluble in
water. Both compounds are highly resistant to chemical, thermal and
biochemical degradation. Mirex is particularly stable in the environment,
with a half-life estimated to be in excess of 10 years. Kepone is one of
the principal biodegradation products of mirex. It's half-life is
presumed to be nearly as long as that of mirex, so that Kepone residues
in the environment will also be long-lasting.
Both mirex and Kepone residues in the environment are analyzed by
gas chromatography (GC) using electron capture detectors. Polychlorinated
biphenyls (PCB's), ubiquitous in the environment, are an interference in
GC analysis of mirex, and can be misintrepreted as mirex unless
eliminated by suitable pretreatment of the sample. Additionally, a
chemically identical compound was also sold a$ Dechlorane for use as a
flame retardant in plastics and polymers. This product was sold in
quantities three times as large as those of mirex, and some of this may
have been released into the biosphere.
Mirex was first used against the imported fire ant in 1961. Through
1975, about 400,000 kg (880,000 Ib) of mirex were sold for agricultural
use. On the basis of USDA records of mirex application, approximately
190,000 kg were used in the southeastern United States in the
Federal-state program for control of the imported fire ant. Several
thousand kilograms of mirex were also applied through independent state
programs. Total U.S. use for fire ants is estimated to have been about
250,000 kg. Much of the other 150,000 kg was evidently exported.
Considerable quantities were used in Brazil against the fire ant.
The U.S. Environmental Protection Agency, after a lengthy hearing on
mirex, placed the use of mirex for fire ant control on a phase-down
schedule, under which aerial application was to terminate December 31,
1977- Under this schedule, approximately another 25,000 kg of mirex were
aerially applied in 1976 and 1977-
Kepone had essentially no agricultural uses in the U.S. Small
quantities were used for control of the tobacco wireworm, and Kepone was
registered for use against the banana root borer in Puerto Rico. Almost
all (90 to 99 percent) of the 1,600,000 kg manufactured between 1959 and
1975 appears to have been exported.
The principal domestic use for Kepone was in ant and roach traps,
around homes and businesses. Data on the quantities so used are not
available, but Kepone concentration in the bait was only 0.125 percent,
and the tonnages are estimated to have been relatively small.
•Dechlorane is a registered trademark of Hooker Chemicals
and Plastics Corporation.
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1.2 EFFECTS ON MICROORGANISMS
Almost no data have been reported on the effects of mirex and Kepone
on microorganisms. The few data which are available indicate very few
effects at concentrations levels likely to be encountered an a result of
normal usage of either pesticide. Sewage sludge microorganisms appear to
be capable of metabolizing mirex under anaerobic conditions, but the
process is very slow. Beneficial bacteria were reported killed in sewage
treatment facilities at Hopewell, Virginia, upon the addition of large
quantities of Kepone wastes.
1.3 EFFECTS ON PLANTS
Very few data are available on the effects of mirex and Kepone on
plants. The growth of several clovers and grasses is inhibited by mirex
in soil at concentrations of 0.15 to 0.70 ppm. Mirex accumulation in crop
plant seedlings was shown to be directly related to soil concentration in
the 0.3 to 3.5 ppm range; however, no data were presented on mirex
translocation to edible plant parts. Mirex soil concentrations from
aerial application of fire ant control bait are much lower than this,
seldom exceeding a few ppb.
Plant root preparations known to metabolize other chlorinated
hydrocarbons failed to yield any metabolite when incubated with mirex.
Essentially no data are available on the effects of Kepone on
plants, and no data were found on the metabolism of Kepone by plants.
1.1 EFFECTS ON BIOTA
Mirex and Kepone have some differences in their effects on aquatic
and terrestrial biota, but have a great many similar effects which is not
surprising in view of their structural and chemical similarity.
Mirex, in realistic environmental concentrations, does not appear to
be directly toxic to marine algae or freshwater plankton. Its extremely
low solubility, 1 ppb or less, may contribute to this. However,
bioaccumulation by algae is possible, and represents a possible route of
entry into the food chain.
The effects of mirex on invertebrate species, especially marine
crustaceans, vary from irritability to loss of equilibrium to death.
Juvenile pink and brown shrimp and juvenile blue crabs are among the
species most susceptible to mirex. Mirex is accumulated by fish from
water and from food-chain organisms; it is concentrated mainly in the
fatty tissue and visceral organs.
Mirex does not appear to present a serious acute toxicity problem to
nontarget terrestrial invertebrates as a result of fire ant control
efforts.
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In comparison to mammals and fish, birds are not extremely sensitive
to mirex in either acute or chronic exposures. However, reproductive
difficulties such as decreased egg production, decreased survival of
chicks, reduced hatchability, and eggshell abnormalities have been
observed in several bird species. Wildlife sampling surveys in or near
treated areas have shown-that birds, as a group, contain relatively high
levels of mirex.
Mirex does not have a high acute oral toxicity for those mammalian
species which have been tested; many other organochlorine and
organophosphate pesticides have much lower LD,.'s. The most commonly
observed subacute toxic effects of mirex in mammals are weight loss,
increased liver weight, and reproductive difficulties.
However, mirex has the highest chronicity factor observed in any
pesticide examined to date. This factor compares the single dose LD,..
with the 90-dose LD_0, and is an indication of the cumulative effects or
substances without reference to their absolute toxicities. This fact,
coupled with the slow excretion and lack of metabolism of mirex indicates
that it is highly cumulative in effect.
Mirex (and Kepone) produce similar adverse reproductive effects in
numerous species tested, including reductions in fertility and litter
size, decreases in birthweight and survival of young, visceral anomalies,
and elevated pesticide levels in offspring.
Mirex produces liver tumors in mice and rats and is judged to have
potential carcinogenicity.
Kepone also has a low solubility, about 1 to 2 ppm in natural
waters. Algal species accumulate Kepone from water and may pass the
pesticide along the food chain to man. Kepone is acutely and chronically
toxic to estuarine invertebrate species, and like mirex, may cause loss
of equilibrium. Bioconcentration factors differ among invertebrate
species because of differences in depuration rates; these are relatively
rapid in oysters, but relatively slow in shrimp.
Kepone is bioaccumulated and persistent in fish. Symptoms of Kepone
exposure may range from diminished activity and emaciation to abnormal
development and mortality.
Data on effects of Kepone on nontarget terrestrial invertebrates are
scant, but indicate it is not acutely toxic. Like mirex, Kepone has a low
order of acute toxicity to birds, although in subacute dosages it is
considerably more toxic than mirex. Tremors, pathologic changes in the
liver, and reproductive difficulties similar to an "estrogenic effect"
are seen in both sexes at dietary levels of 200 ppm of Kepone.
Kepone, both in oral and dermal administrations, is more acutely
toxic than mirex in mammalian species. The most characteristic symptom of
acute or subacute Kepone intoxication in mammals is severe and persistent
-------
tremor. Enlargement and congestion of the liver, weight loss, increased
oxygen consumption, and urinary excretion of protein and sugar were
reported in chronic toxicity studies on rodents and dogs.
Like mirex, excretion of body burdens of Kepone is slow. Similar to
mirex, no metabolites of Kepone have been detected in Kepone-fed mice. As
with mirex, the indications are that the biological stability of Kepone
in the body is great. Excretion of the body burden of Kepone is slow, and
no metabolites have been detected.
The reproductive effects of Kepone are similar to those previously
described for mirex. In addition, oncogenic and carcinogenic properties
of Kepone have been documented in rats and mice.
1.5 EFFECTS ON HUMANS
Human exposure to mirex and/or Kepone has been documented through
analytical confirmation of residues of both pesticides in human tissues
and man's food chain and, in the case of Kepone, by epidemiologic and
medical surveillance of workers engaged in the manufacture of Kepone, and
a systematic survey of a community where Kepone was manufactured.
Potential sources of exposure of humans to mirex are believed to be
related to mirex bait application in fire ant control programs. There are
few definitive data concerning the effects of mirex on humans. Neither
acute nor chronic exposures appear to have been recorded, in either
manufacture or use, and no clinical data were identified during this
study.
Because mirex is a very stable insecticide capable of being stored
in fat, the U.S. Department of Agriculture conducted a survey of the
mirex content of beef fat from cattle which had grazed on treated
pastures, in comparison to cattle from outside the treated areas.
Residues were found in 88 percent of the beef fat samples from cows on
treated pasture, with an average mirex content of 0.026 ppm, however,
only one sample exceeded the established tolerance level of 0.1 ppm. No
residues were found in organs, nor in the fat of cattle from outside the
treated areas.
In another survey on the mirex content of milk, none of 60 samples
from treated areas had detectable concentrations of mirex, at a detection
limit of 0.3 ppb.
Mirex residues have been found in adipose tissue of humans living in
treated areas. Approximately 19 percent of 284 samples analyzed had
quantifiable levels of mirex, ranging from a trace to 1.2 ppm. Generally,
the highest percentage of positive results correlated with the areas
having a history of heaviest mirex usage.
Potential sources of exposure of humans to Kepone from its
pesticidal use against ants and roaches appear to be minimal. No
-------
pesticidal uses involved dispersion on a large scale, as did mirex; the
principal Kepone use was in baited insect traps, used domestically.
The major source of human exposure to Kepone resulted from its
manufacture at the Life Sciences Products Company at Hopewell, Virginia.
A large majority of the past and present employees at this plant
exhibited symptoms of exposure to Kepone. Between the commencement of
operations in March, 1974 and their termination in July, 1975, 76 (57
percent) of the workers contracted an illness compatible with Kepone
toxicity. The principal manifestations of the poisoning were nervousness,
tremor, weight loss, opsoclonus (erratic or jumpy eye oscillations) and
pleuritic chest pains. These symptoms closely resembled those seen in
animals suffering from Kepone intoxication.
Recent studies by physicians involved in treatment of these affected
Kepone workers suggest that oral treatment with cholestryamine resin may
be efficacious by facilitating Kepone excretion.
A systematic community survey, conducted to establish the geographic
limits of the Kepone exposure area in Hopewell, showed that 40 of 216
blood samples contained from 5 to 50 ppb Kepone. Thirty-four of these 40
were from a residential area within 400 meters of the LSPC plant; none of
the persons reported ever having worked with Kepone.
As a result of uncontrolled and unauthorized discharges of Kepone to
the James River from the LSPC plant, the river sediments have been
contaminated over a wide area to such an extent that "action levels" have
been established by EPA for shellfish, finfish, and crabs.
Kepone has been detected in mother's milk gathered in the
southeastern United States (9 of 298 samples), but at such low levels (<1
ppb to 6 ppb) that the hazards posed, if any, are uncertain.
1.6 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
The principal route of entry of mirex into the environment has been
the aerial application during the past 15 years of perhaps as much as
275,000 kg (600,000 Ib) of mi rex-dosed bait to millions of hectares in
the southeastern U.S. for fire ant control. The corncob baits used
contained variously 0.30, 0.15, or, most recently, 0.10 percent of mirex.
Typical rates of application of mirex were extremely low, 4.2 g/ha (1.7
g/ac). At this rate, the calculated concentration of mirex in the top 7.5
cm (3 in) of soil would be 5 ppb or less, a remarkably low environmental
concentration for an agricultural pesticide.
There is considerable uncertainty about the extent of dispersion to
the environment of the approximately 1,125,000 kg (2,500,000 Ib) of
chemically identical compound sold for non agricultural use under the
name Dechlorane. It's principal use was in plastics and polymers, to
impart flame retardant properties. There is essentially no information on
the ultimate fate of this far larger quantity of C1QC112. If the plastic
-------
products containing the Dechlorane were disposed of in landfills instead
of to an incinerator, the Dechlorane should be fairly well immobilized,
and a source of only localized pollution. Additional investigation is
needed to assess the environmental impacts of this use.
A second identified source of environmental dispersion of mirex
results from losses during manufacture and handling of mirex/Dechlorane.
Two "hot spots" have been discovered in Lake Ontario; one is presumed to
have resulted from losses from the plant where mirex/Dechlorane was
manufactured, and the other from a spill of Dechlorane fire retardant
which occurred about 15 years ago. Surveys of Lake Ontario suggest that
lake sediments may contain several hundred kilograms. These data suggest
also that biodegradation is proceeding very slowly. Confirmation of the
slow biodegradation of mirex is supplied by the detection of substantial
residues in soils 5 and 12 years after mirex was deposited.
The measured solubility of mirex in water is 1 ppb or below, and
mirex in natural waters in areas where mirex has been used is frequently
undetectable at a detection level of 0.01 ppb. Dissolution of mirex in
water does not appear to be a significant mode of transport. However,
mirex accumulation has been noted in nontarget aquatic organisms.
Concentrations resulting from its pesticide use have been below levels
deemed harmful to man, but contamination levels in some species of Lake
Ontario fish have resulted in a ban on their consumption.
There appear to be no data on concentrations of mirex in air, either
in the vicinity of manufacturing sites or in areas where mirex has been
applied. The low vapor pressure and the method of application of the
mirex in a bait formulation suggests that ambient atmospheric
concentrations are likely to be at the limit of detection or below.
The principal route of entry of Kepone into the enviroment was gross
uncontrolled discharges from the plant which manufactured Kepone for the
last year and one-half before its manufacture in the U.S. was terminated.
Kepone had very minor agricultural uses, and its principal domestic use,
in bait traps for ants and cockroaches, was not only a small tonnage use,
but also did not significantly disperse it to the biosphere. Thus, prior
to the Life Sciences Products Company incident, essentially no data
existed on environmental concentrations of Kepone, and almost all of the
environmental distribution data since acquired relate specifically to
this incident.
Contamination of James River sediments from Hopewell, Virginia,
nearly to Newport News has been demonstrated. Unacceptable concentrations
have been detected in both invertebrates and fish, and upper limits have
been established for oysters, clams, mussels, crabs, and finfish for
human consumption. It has been estimated that thousands of kilograms may
be trapped in James River sediments. No practical scheme for its removal
or neutralization has yet been devised. Since Kepone, like mirex, is
highly resistant to biodegradation, this inventory will pose a problem
for many years.
-------
Concentrations of suspended particulate Kepone in the atmosphere
were variable and high near the LSPC plant during the period that Kepone
was being manufactured. Except for this special case, Kepone would be
expected to be undetectable in the atmosphere. In its normal use in bait
traps for ants and roaches, the low vapor pressure of Kepone would
preclude any significant release.
8
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2.0 TECHNOLOGY OF MIREX AND KEPONE
2.1 SUMMARY
p
Mirex (C10C112^ and Kepone (C.-d.-O) are related chemically,
Kepone being the ketone analog of mirex. Accordingly, the compounds have
many similarities. Both are produced from hexachlorocyclopentadiene; both
are moderately soluble in organic solvents, and both have extremely low
solubilities in water. Solubility of mirex in water is approximately 1
ppb (0.001 ppm); that of Kepone is higher, but still is low, only 1 to 2
ppm.
Mirex, consistent with its fully chlorinated structure, is one of
the most stable organochlorine pesticides, and is highly resistant to
chemical, thermal, and biochemical degradation. Thermal decomposition
begins to occur at 550 to 600 C, and is rapid at 700 C. At these
temperatures, degradation products include hexachlorobenzene and
hexachlorocyclopentadiene. Mirex is resistant to photolysis in
hydrocarbon solvents, but less so in aliphatic amines. Current research
indicates that by using amines it may be possible to prepare mirex baits
which decompose in 4 to 6 weeks. Mirex has a long half-life in the
environment. Large fractional residues have been detected at two
locations, 5 to 12 years after the initial application. Kepone was
identified as one of the degradation products.
Kepone, with its carbonyl bond and its less fully chlorinated
structure, is slightly less resistant than mirex to chemical and thermal
degradation. Thermal decomposition begins to occur at about 350 C, and is
rapid at 450 to 500 C. In addition to the hexachlorobenzene and
hexachlorocyclopentadiene degradation products observed with mirex, a
third product, possibly octachloroindene (CQClg), has been observed. When
Kepone is exposed to 900 C for approximately 1 second, decomposition is
essentially complete.
The usual method of analysis for both compounds at the extremely low
concentration levels found in environmental samples is gas
chromatography, using electron capture detectors. Interferences from
polychlorinated biphenyls now ubiquituous in the environment have to be
guarded against in the analysis. Since there are over 200 PCB isomers,
several of which can masquerade as mirex, results reported in the
literature may be suspect for this reason. Additionally, a chemical
compound identical to mirex was sold for use as a flame retardant for
polymeric and plastic materials under the name Dechlorane, in quantities
three times as large as those of mirex. Some of the reported findings of
mirex in the environment undoubtedly derived from this Dechlorane source.
-------
Mirex has been used since 1962 in the southeastern states for control
of the imported fire ant. Because of its efficacy of use in a bait
formulation particularly attractive to fire ants, extremely gmall rates
of application are required. As little as 4.2 g/ha (1.7 g/ac) provides
effective kill in an infested area. However, permanent eradication has
not been possible with the control approaches used; the mobility and
range of the winged fire ant queens result in reinfestation from
neighboring areas.
Total mirex application through 1975 for imported fire ant control in
the U.S. is estimated to have been no more than about 250,000 kg (550,000
Ib). Although mirex has also been used on a smaller scale for control of
the western harvester ant, the Texas leaf-cutting ant and the Hawaiian
pineapple mealybug, the quantities have been small relative to those used
for fire ants. Total production in the U.S. of mirex through 1975 was
approximately 400,000 kg (800,000 Ib), but it is estimated that
approximately 150,000 kg (330,000 Ib) of this was exported for pest
control in other countries.
Kepone's main use has been as a pesticide for the banana root borer,
outside of the United States. There are no large-scale agricultural uses
in the U.S. Its principal use was around homes and buildings as an ant
and roach poison in the form of baits or traps containing only 0.125
percent active ingredient. Total production of Kepone, from its initial
manufacture in 1951 through its suspension in August, 1975, was about
1,600,000 kg (3,500,000 Ib) of which from 90 to 99 percent appear to have
been exported. (Much of this exported Kepone was apparently not used
directly as a pesticide but was converted to other pesticidal compounds,
e,g., Kelevan).
2.2 STRUCTURE AND PREPARATION
Mirex and Kepone are two representatives of the large family of
cyclodiene insecticides synthesized from hexachlorocyclopentadiene. Mirex
is a white, odorless crystalline compound composed entirely of carbon and
chlorine atoms, with the empirical formula CCl..-. In the United States,
•This small quantity has been further reduced by recent improvements
in bait formulations. The 1977 program used a 0.1 percent bait at a
rate of 2.5 kg/ha (1 Ib/ac), equivalent to 0.45/g/ac of active
ingredient. Experimental degradable baits containing even smaller
concentrations (0.05 and 0.025 percent mirex) have been developed
and are being tested.
10
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the common chemical name is dodecachlorooctahydro-1,3,^-metheno-2H-
cyclobuta (cd) pental e-n,e ;_ ± hjfi „systematic name is
dodecachloropentacyclo 5.3.0.0 '.O^'.O' decane. The Allied Chemical
Corporation used the name Dechlorane for the same compound utilized as a
flame retardant in polymeric materials (Alley, 1973). Chlordecone,
decachlorooctahydro-1,3,4-metheno-2H-cyclobuta (cd) pentalene-2-one
(trade names GC-1189 or Kepone) is the ketone analog to mirex, with the
empirical formula C10C11Q0. Commercial Kepone is a white to tan solid
which sublimes, with some decomposition, at about 300 C.
An excellent discussion of the structures and preparative procedures
for the insecticides of the diene-organochlorine group, including mirex
and Kepone, is found in "Chlorinated Insecticides, Volume I", by Brooks
(197*0. Brooks notes that mirex can be prepared directly by the reaction
of hexachlorocyclopentadiene ("hex") with itself in the presence of
aluminum chloride, or by the reaction of Kepone with phosphorus
pentachloride. The preparation and the cage structures of mirex and
Kepone are shown graphically in Figure 2.1, from Brooks.
so.
Hex'
-» sulforulion products
hydrolysis
i
Kepone
Figure 2.1 Synthesis of Mirex and Kepone
Source: Reprinted, with permission, from
Chlorinated Insecticides, Vol. I. (c) The
Chemical Rubber Co., CRC Press, Inc. (197*0.
11
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As described by Brooks (1974).
"When hex is treated with sulfur trioxide, fuming sulfuric
acid, chlorosulfonic acid or sulfuryl chloride at 35 to 80 C, it reacts
with itself by addition to give a cage structure in which the allylic
chlorine atoms of one molecule are substituted by hydrolyzable sulfur
containing groups. The intermediate (or intermediates) loses sulfur on
hydrolysis to give the corresponding cage structure (70 percent yield)
containing a carbonyl bridge, which has been marketed as an insecticide
under the trademark Kepone, also known as chlordecone (Figure 2.1). The
technical product is more than 90 percent pure, and sublimes, with some
decomposition, near 350 C."
"When heated with phosphorus pentachloride at 125 to 150 C, the keto
group is replaced by two chlorine atoms to give mirex, a C1QC112
chlorinated hydrocarbon (Figure 2.1), identical with the product formea
directly from hex by heating it with aluminum chloride either without
solvent or in methylene chloride, carbon tetrachloride,
tetrachlorethylene, or hexachlorobutadiene"-
2.2.1 Hexachlorocyclopentadiene
Hexachlorocyclopentadiene ("hex") is the precursor of both mirex and
Kepone. It is also the starting material for numerous organochlorine
insecticides, including aldrin, dieldrin, heptachlor, endrin, chlordane,
endosulfan, and Pentac , and for a number of chlorinated compounds used
to impart flame resistance to resins and plastics. Thus, production of
hex has been large. Whetstone (1964) estimated 1962 production as at
least 22.5 million kg (50 million Ib) in 1962; Lu, et al., (1975)
estimated 1975 production at about the same level.
Since hex is primarily utilized as a chemical intermediate, with no
significant end uses of its own, essentially none of this toxic substance
is intentionally dispersed into the environment. However, in view of the
large production quantities the possibilities of loss of hex and its
byproducts during manufacture and use cannot be disregarded.
Additionally, unreacted hex is a potential contaminant in a number of the
products made from hex.
During the course of the current study it became apparent that the
environmental impacts of hexachlorocyclopentadiene and related compounds,
heretofore seriously neglected, warranted further investigation. An
investigation of hex is currently in progress which will be the subject
of a separate report, to be issued soon. The present report considers
only mirex and Kepone.
12
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2.3 CHARACTERIZATION OF MIREX AND KEPONE
2.3.1 Physical and Chemical Properties
2.3-1.1 Mirex—
Mirex (C10cii2^ is a whifce» crystalline, free-flowing solid of
molecular weight 545 whose preparation was first described by McBee, et
al.f (1956). Reported melting point was 485 C. According to Brooks (1974)
mirex has a vapor pressure of 6 x 10~ mm Hg at 50 C.
Mirex is fairly soluble in organic solvents. Brooks reported the
following solubilities:
Solvent
Methyl ethyl ketone
Carbon tetrachloride
Benzene
Xylene
Dioxane
Percent
5.6
7.2
12.2
14.2
15.2
Alley (1973) summarized the solubilities of mirex as follows:
Solvent
Ethyl alcohol
Acetonitrile
2-Butanone (MEK)
Piperidine
Morpholine
Pyridine
Diethyl ether
Tetrahydrofuran
g/100 ml Solvent
0.7 Cyclohexane
0.4 Isooctane
4.2 n-Hexane
11.3 Toluene
14.5 Carbon disulfide
10.1 Methylene
9.1 Chloroform
30.3 Carbon tetrachloride
g/100 ml
3-4
2.1
2.8
14.
18.
10.
17.
.3
1
.2
.2
5.9
Mirex has a very low solubility in water, not exceeding 1 ppb (de La
Cruz and Naqvi, 1973). Hollister, et al., (1975) reported evidence that
0.2 ppb mirex was the maximum solubility possible in seawater. Alley
(1973) indicated even lower solubilities:
Solubility, ppb
Water 1
Water, 0.5* salinity 0.25
Water, 2.5* salinity 0.11
Water, 4.0* salinity 0.04
Technical mirex has a high purity in comparison to a number of other
chlorocarbon insecticides. Analysis of technical mirex for Kepone content
13
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by the Chemical and Biological Investigations Branch of EPA, Beltsville,
Maryland, showed mirex content to exceed 95 percent, with only traces of
Kepone present (U.S. Environmental Protection Agency, 1976).
Kepone Content of Technical Mirex
Mirex Content, Kepone Content,
Matrix Percent ppmw
Technical grade mirex 95.19 2.58
Technical grade mirex 1.71 2.38
in soybean oil
Technical grade mirex 0.26 0.25
in soybean oil on
corncob grits
2.3-1.2 Kepone—
As described in a Development Information Bulletin (Allied Chemical
Corporation, 1958a), Kepone is a stable, white to tan solid which
sublimes, with some decomposition, at about 300 C. It is readily soluble
in acetone, lower aliphatic alcohols, and somewhat soluble in benzene,
toluene, and hexane. It is nearly completely soluble in aqueous sodium
hydroxide. Subsequent Allied Chemical Corporation data, reported by Smith
(1976), indicated that the aqueous solubility is 1.5 to 2 ppm over the pH
range of 4 to 6. In the 9 to 10 pH range, solubility increases to 5 to 70
ppm. In 0.001 M NaOH (pH 10.9) solubility is 176 ppm.
Upon exposure to ordinary temperatures and humidities, the anhydrous
compound readily takes up water, up to three molecules of water. (Allied
Chemical Corporation, 1958a). The trihydrate, c-tQci^nQ ' 3H_0 (9-92
percent water) appears to be the stable form. Because tine anhydrous form
takes up moisture rapidly during mixing and milling steps, it was not
considered satisfactory for dust bases and water-dispersible powders. On
the other hand, the trihydrate was not considered to be entirely
satisfactory for producing emulsifiable concentrates. However,
compositions between the monohydrate (3-54 percent water) and the
dihydrate (6.84 percent water) were regarded as satisfactory for both
uses, so that total water specifications for technical Kepone were
established at 3*5 - 6.0 percent (Allied Chemical Corporation, 1958b).
The average analysis of Kepone produced during the 1966 Allied
Chemical Corporation semiworks production campaign was as follows (Smith,
1976):
-------
Percent by Weight
Water 5.2
Methanol insolubles 0.3
Hexachlorocyclopentadiene 0.1
Sulfate 0.03
Kepone 9^.4
2.3.2 Chemical and Thermal Stability
Both mi rex and Kepone possess a high degree of chemical and thermal
stability; Kepone is somewhat less stable than mirex, presumably as a
result of the replacement of two chlorine atoms with a carbonyl bond.
2.3.2.1 Mirex—
Mirex is notably stable. McBee, et al., (1956) reported it
unaffected by the following: zinc dust and hydrochloric acid, acetic
acid, or methanol; silver nitrate and ethanol for long periods; alkaline
reagents such as potassium hydroxide in methanol or lithium hydride in
ether; and oxidizing agents such as ozone, potassium permanganate,
chromic acid, sulfur trioxide, sulfuric acid, or nitric acid. However,
Billing, et al. , (196?) found that mirex reacted with lithium and
tert-butyl alcohol to give a saturated hydrocarbon and
endo-dicyclopentadiene.
There is general agreement that mirex is thermally very stable. In
the pioneering work of McBee, et al., (1956) it was found that mirex
underwent pyrolysis only at very high temperature (500 C or above),
giving largely carbonaceous material and chlorine, with only a small
amount of hexachlorocyclopentadiene. Eaton, et al., (1960) performed
pyrolysis tests at 500 C in flowing nitrogen; the condensate was found to
be unchanged starting material contaminated with small amounts of
hexachlorocyclopentadiene. On the basis of more recent work, it is
considered possible that vaporization was the predominant reaction
occurring under these experimental conditions.
Holloman, et al., (1975) investigated the major thermal degradation
products of mirex. These pyrolysis experiments were conducted by sealing
50 to 100 mg of analytical standard grade mirex in 10-ml Neutraglas
ampules and heating them in a muffle furnace for 30 minutes at the
selected temperature. After cooling the ampules were broken and the
contents dissolved for analysis in pesticide grade hexane. No degradation
was detected below 525 C, in agreement with McBee, et al., (1956) and
Eaton, et al. , (1960). At 525 C, the principal product was
hexachlorobenzene, with traces of hexachlorocyclopentadiene. A sample
heated to 550 C in an ampule lost on the average, 15 percent of its
original weight. The residue remaining was found to be 72 percent
hexachlorobenzene, verified by mass spectrometric, infra red (IR),
ultraviolet (UV), and gas-liquid chromatographic (GC) analyses. Other
15
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tests indicated that hexachlorocyclopentadiene, postulated as the most
probable mode of fragmentation, exists only a short time at pyrolysis
temperatures, and is rapidly converted to hexachlorobenzene.
In recent research on suitable methods for the disposition of
unwanted stores of Kepone and Kepone-contaminated materials,
high-temperature controlled incineration has been investigated by Duvall
and Rubey (1976), under the sponsorship of the EPA. Both mirex and Kepone
were included in the study, and new insight on their thermal stabilities
has resulted from this investigation.
The objective of the study was to obtain laboratory test data which
could be applied to large-scale thermal destruction of Kepone and similar
pesticides, using oxidative rather than pyrolytic conditions. Tests were
conducted at a series of temperatures ranging from 250 to 900 C. Pure
pesticide was vaporized at a low temperature, 200 to 300 C, and the vapor
was passed through a high-temperature quartz tube in a furnace at
constant temperature; residence time (1 second) was controlled by the
rate of air flow. The effluent from each test was trapped and
subsequently analyzed by gas chromatography. Results of the mirex tests
are shown in Figure 2.2.
In agreement with the findings of previous investigators, mirex
decomposition began to occur in the 550 to 600 C range, and was rapid at
700 C. In companion thermogravimetric analyses, vaporization commenced at
about 140 C and was complete by 230 C. Two principal degradation products
were observed. One, whose concentration peaked at about 700 C, was
determined by GC to be hexachlorobenzene (peak Me). The second, observed
only in the test at 600 C, was hexachlorocyclopentadiene. On the basis of
the analogous Kepone experiments, it appears that the decomposition
temperature for mirex probably overlaps that for hex to the extent that
the hex peak essentially disappears.
Mirex is also notably resistant to photolytic decomposition in the
environment. Gibson, et al., (1972) have conducted both field and
laboratory experiments. Radioactively-labelled C-mirex deposited on
thin layers of silica gel (Eastman Chromagram Sheet No. 6016) was exposed
to sunlight in the environment. After three months of exposure, the gel
was extracted with methanol and the extracts were analyzed by GC and TLC
(thin-layer chroma tography). The principal photoproduct comprised only 5
percent of the total persisting residue. The major mirex photoproduct was
also prepared in the laboratory by irradiating silica gel deposits with
artificial light (fluorescent sunlamps) at a lamp to subject distance of
7 cm for 48 hrs. The compound prepared by artificial light exhibited
identical behavior on TLC and GC with the product from actual
environmental exposure. Although both procedures indicated one or more
minor photoproducts, the remaining residue consisted almost exclusively
of unchanged mirex.
16
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100
30
2 ID
g
CO
UJ
cc
i 3o
UJ
4
g 03
O.I
OO3
ox>r
[MJ MIREX
ZOO 4OO 600 SCO
TEMPERATURE. • C
iOOO
Figure 2.2 Thermal destruction plot for mirex.
Adapted from Duvall and Rubey (1976).
Evidence suggested that the photoproduct was a monohydro derivative
of mirex. The symmetry of the carbon nucleus of mirex (Structure I)
permits only three isomeric monohydro derivatives:
--CI
II
17
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Compound II was prepared by lithium-aluminum hydride reduction of Kepone
and subsequent chlorination of the alcohol with phosphorus pentachloride
by Dilling, et al. , (1967), and its structure was determined
unambiguously. In addition, a second monohydro isomer was produced but it
was not possible to determine whether its structure was III or IV.
Gibson's photoproduct differed from II on the basis of TLC, GC, IR, and
proton magnetic resonance (PMR) analysis. Thus, the photoproduct was
deduced to be either III or IV, although it was not possible to
distinguish between the two.
Alley, et al., (1973) obtained similar results upon irradiating
mirex, (0.04 M) in hydrocarbon solvents (cyclohexane or isooctane) with a
mercury UV lamp. After 48 hrs irradiation 95 percent of the mirex had
disappeared, with a 40 percent yield of photoproducts. Of the two major
photoproducts, the mass spectra indicated one to be a monohydro
derivative and the other a dihydro derivative. Structure II was ruled out
for the monohydro photoproduct on the basis of GC and IR analyses. Alley
et al., (1973) and Alley, et al., (1974a) have assigned Structure III to
the monohydro photoproduct. Photolysis of the purified monohydro
photoproduct revealed that it was a precursor of the dihydro
photoproduct. Nuclear magnetic resonance (NMR) and IR analyses suggested
that the dihydro derivative has more symmetry than the monohydro
derivative. Alley, et al., (1974a) assigned structure VII for the dihydro
compound.
H
H
- -a
'10
Alley, et al., in a later paper (1974b) cited research by Zijp and
Gerding (1958) which showed that mirex has virtually no absorption at
wavelengths greater than 250 nm, and thus concluded that very little
photochemical degradation by sunlight would be expected. This is
consistent with the results of Gibson, et al., (1972) and of Carlson, et
al., (1976). However, work of Alley, et al., showed that the degradation
of mirex by sunlight was significantly enhanced by its interaction with
aliphatic amines, e.g., triethylamine.
The photodecomposition of mirex in aliphatic amines proved to be
different from that observed in hydrocarbon solvents in two important
aspects, the product obtained and the wavelength of light absorbed. The
major photoproduct (verified by its IR spectrum) was the monohydro
18
-------
derivative, II. A second monohydro photoproduct, III, was formed in
smaller quantities. In addition, a mixture of dihydro products was also
formed.
The wavelength of light required for the reaction was different in
amines from that in hydrocarbons. Sunlight or sunlamp caused rapid
decomppsition of mirex in amines, but no reaction could be detected under
similar conditions when the solvent was cyclohexane. The enhancement of
decomposition is attributed to a charge transfer complex between the
amine and mirex. Similar observations of photodecomposition of pesticides
promoted by aromatic amines have been reported by others.
It was suggested by Alley, et al., that it might be possible to
devise photodegradable formulations of mirex by the incorporation of
amines into the bait used for control of the imported fire ant. Holden
(1976) indicated that this approach was being followed up. More recent
information (Alley, 1977)'disclosed that a considerable degree of success
has been achieved. Baits which are still attractive to fire ants but
which decompose in the environment in 4 to 6 weeks have been developed
and field tested. Efficiency of the new type of bait is good, even at low
application rates. Decomposition proceeds both photolytically and
thermally; at 30 C photolytic decomposition by sunlight is 3 to 4 times
faster than thermal decomposition. Thermal decomposition is enhanced by
the addition of ferrous chloride. Indications are that the toxicity of
the successive degradation products decreases from monohydro to dihydro
to trihydro. Toxicity studies w.ill be necessary to determine the overall
safety of this new type of bait , but it appears to possess considerable
advantage over the original mirex bait.
Some of the most definitive evidence of the exceptional stability of
mirex in the environment was recently reported by Carlson, et al.,
(1976), who investigated two field locations where unusually large
amounts of mirex were deposited and left for 12 to 5 years. The first
location was near Gulfport, Mississippi, where mirex (on attapuulgite
clay) was applied in 1962 to experimental plots in a fire ant control
test at the rate of 1.12 kg mirex/ha (1 Ib/ac). Present dosage is at a
recommended rate of 1.7 or 3.4 g mirex/acre (4.2 to 8.4 g/ha). Soil cores
and samples of the loose, sandy soil were gathered from three plots in
1974 and held in sealed metal cans until extraction.
The second location was near Sebring, Florida, where an airplane
carrying granulated 4X type mirex bait crashed in 1969 at the edge of a
small shallow pond, dumping its entire load of bait into the pond. The
resulting layer of bait which contained 0.3 percent of mirex (3000 ppm)
covered an area of approximately 3 m in diameter and about 0.25 meter
deep, in a location usually under water about 0.2 to 0.5 m. The water has
been observed to recede in the spring, exposing the bait to sunlight.
Samples of bait and the underlying muck were collected in March, 1974 and
analyzed by GC, TLC, and gas chromatography-mass spectrometry (GC-MS).
•Designated as Ferriamicide
19
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Analysis by GC of crude extracts showed detectable quantities of two
monohydro products, two dihydro products, and Kepone. In the Gulfport
samples the concentration of mirex plus degradation products represented
about 50 percent of the mirex applied 12 years before. Kepone represented
3 to 6 percent of the total residues; unchanged mirex ranged from 65 to
73 percent. Similarly, in the Sebring samples, mirex ranged from 76 to 81
percent and Kepone comprised 1 to 6 percent (Table 2.1). Identity of the
decomposition products was verified by GC, by computer-reconstructed gas
chromatograms (RGC), and by limited mass chromatograms (LMS) from stored
chemical ionization spectra.
The authors note that this decomposition sequence is likely to occur
at any location where mirex bait is deposited on the soil, and that
although Kepone is the second most abundant product observed (up to 10
percent as much as the recovered mirex) it is just one of a succession of
products formed by exposure of mirex to light. Thus, this demonstrates a
pathway by which mirex can disappear from the environment.
Lane, et al., (1976) presented the results of a study designed to
assess the possible alteration of mirex during food processing via UV or
gamma radiation. When eggs from mallard ducks, Anas platyrhychos, which
had been fed diets containing mirex at levels of 1 and 100 ppm for 25
weeks were subjected to UV and gamma radiation, a number of degradation
products were observed. Seven derivatives were obtained from photolysis,
and eight from gamma irradiation; results of combined gas
chromatography—mass spectrometry are summarized in Table 2.2. Mirex
residues after UV radiation (1 ppm mirex diet) were:
Control, ppm 2.48+0.05
24 hours, ppm 2.04+0.04
48 hours, ppm 1.60+0.07
Mirex residues after various dosages of gamma radiation (100 ppm mirex
diet) were:
Control, ppm 232.00+12.84
1000 rad, ppm 206.99+ 7-63
2000 rad, ppm 163-52+ 4.80
3000 rad, ppm 130.96+ 3-14
4000 rad, ppm 85.45+ 1.41
Photolysis caused a 36 percent decrease in mirex at 48 hours whereas
gamma irradiation at 4.5 M rad caused a 64 percent decrease. A linear
relationship existed between loss of mirex and time for both UV and gamma
irradiation. Peak 7» the major photolytic and gamma irradiation product
of mirex, corresponds to the major monohydro photolysis product obtained
by Alley, et al., (1974a), and Peak 8 corresponds to the compound
obtained more recently by these same investigators by photoreduction of
mirex in triethylamine (Alley, et al., 1974b). The compounds of peaks 5
and 6 were found to be isomeric and unsymmetrical dihydro derivatives of
mirex, with Peak 7 being the precursor compound. Peak 4 proved to be a
20
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TABLE 2.1. COMPOUNDS AND CONCENTRATIONS FOUND IN RECOVERED
SOIL AND BAIT SAMPLES AFTER 5 AND 12 YEARS3
c
Gulfport Samples, ppm
Compounds
Mirex
Monohydro
Monohydro
Dihydro
Kepone
Dihydro
Total
*tb
1.00
0.76
0.67
0.52
0.48
0.42
Plot
27
0.497
0.014
0.110
0.019
0.021
0.021
0.682
Plot
42
0.310
0.015
0.092
0.010
0.026
0.018
0.471
Plot
70
0.192
0.010
0.054
0.012
0.019
0.008
0.295
d
Sebring Samples, ppm
Surface
Bait6 Muck
633
39
65
14
10
17
0.206
0.013
0.020
0.012
0.015
0.005
0.271
aSource: Carlson, et al, (1976), reprinted with permission from
Science (C) Amer. Assoc. for the Advancement of Science (1976).
b
Retention time relative to mirex (1.00) on a DC-200 column.
Taken 12 years after application.
Taken 5 years after initial dispersion.
Bait mixed with soil in unknown proportion.
21
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TABLE 2.2 UV AND Y IRRADIATION PRODUCTS OF MIREXa
Peak
Retention time relative to Mirex,
10% DC 200 at 195 C
Products
0.30
Not identified
0.32
Not identified
0.37
Not identified
0.42
0.48
0.51
-Clio
H H,
•'W
(Peaks 5 and 6)
8
0.65
0.75
1.00
•-ci,
(obtained in Y radia-
tion only)
Mirex (starting material)
aSqurce: Lane, et al (1976), Reprinted, with permission from
J. Agricultural and Food Chemistry, (c) American Chemical Society
(1976).
22
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mixture of symmetrical dihydro compounds similar to those otained by
Alley, et al., from photolysis of mirex in cyclohexane. No mass spectra
were obtained on Peaks 1, 2, or 3 because of insufficient samples.
2.3.2.2 Kepone—
The thermal and chemical stability of Kepone has been much less
thoroughly studied. Eaton, et al., (1960) performed pyrolysis tests on
Kepone similar to those on mirex (Section 2.3-2.1). As a result of the
lower decomposition temperature of Kepone, quantities of decomposition
products were observed after exposure to 500 C. The principal pyrolysis
product (80 percent yield) was octachloroindene, cC1:
Small quantities of hexachlorobenzene and carbon tetrachloride were
also detected along with trace amounts of hexachlorocyclopentadiene.
Kecher, et al., (1969) confirmed these findings, reporting that when
Kepone was held in a sealed ampule at 250 to 300 C for 1 hr,
hexachlorocyclopentadiene and a degradation product with the nominal
composition of C-Clg were detected in the pyrolysis products.
Duvall and Rubey (1976) have extensively examined the
high-temperature destruction of Kepone and related pesticides; their
findings on mirex are discussed in Section 2.3-2.1. Kepone vaporizes and
decomposes at lower temperatures than mirex. Thermogravimetric analysis
in a flowing air stream showed vaporization commencing at about 95 C and
being essentially complete at 195 C. An early weight loss was observed
between 30 and 50 C, presumably due to the loss of water of hydration.
Under the standard test conditions (*>1 second residence time), Kepone
decomposition began to occur at temperatures above about 350 C, and was
rapid at 450 to 500 C (Figure- 2.3). Hexachlorobenzene (peak K ) was
prominent at temperatures below 600 C, hexachlorocyclopentadiene (peak
Ka) was formed at temperatures below 500 C, and was not found at
temperatures above 600 C. Carnes (1977a) states that the intermediate
peak (K.) was unidentified. The planned addition of GC-MS to the
instrumentation is expected to provide identification of this degradation
product in subsequent studies (Carnes, 1977b). The significant yield of
octachloroindene reported by Eaton, et al., (1960) and confirmed by
Kecher, et al., (1969) may explain the unknown peak.
23
-------
100
10
o
a.
in
o
til
a.
o.
X-
a.
a:
o
K
O
1.0
0.3
O.I
0.03
0.01
KEPONE
1 I 1 I I I I
I I
200 40O GOO
TEMPERATURE, »
BOO
IOOO
Figure 2.3 Thermal destruction plot for Kepone
Source: Duvall and Rubey (1976)
When 40 micrograms of Kepone vapor, in an excess of flowing air, was
subjected to a 900 C environment for approximately 1 second, essentially
only hexachlorobenzene was found in the effluent, and only at nanogram
levels. Residual Kepone trapped was of the order of 100 to 200 picograms
(Duvall and Rubey, 1976). The effect of residence time on Kepone
decomposition at a lower temperature was also investigated in a series of
tests at 433 C. Destruction increased from less than 10 percent at 0.3
second to about 70 percent at 2 seconds (Figure 2.4).
24
-------
100
80
KEPONE
(WT %)
60
40
20
T2 = 433°C
O.I
0.3
1.0
3.0
10
RESIDENCE TIME, SEC
Figure 2.4.
Effect of residence time on thermal
destruction of Kepone
Source: Duvall and Rubey (1976).
2.4 ANALYSIS
2.4.1 Methods of Analysis
Analytical methods for mirex and Kepone are similar to those used
for other chlorinated pesticides. These methods for mirex and Kepone can
be grouped into macromethods suitable for analysis of large quantities of
material, and micromethods suitable for analysis of residues in the
environment at trace or near-trace concentrations. The classical
macroanalytical techniques (e.g., gravimetric, polarographic,
spectrophotometric analyses) useful for product quality control purposes,
are not suitable for residue analysis, and are omitted from the following
discussion. Only the microanalytical methods appropriate for assessing
the environmental effects of these compounds and their degradation
products are considered here.
25
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2.M.1.1 Gas-Liquid Chromatography—
GC is the preferred method for quantitative determination of
pesticides and related compounds in the Pesticides Analytical Manual,
Vol. I. (Food and Drug Administration, U.S.Department of Health,
Education, and Welfare), and is the method used for nearly all the
analytical determinations contained in this document. It is often
supplemented by thin-layer Chromatography to confirm compound identity,
or by mass spectrometry or infrared analysis to determine compound
structure.
In gas-liquid chromatographic (GC) analysis a small quantity of
sample is injected into a column which is packed with an inert carrier
coated with a suitable stationary phase. When a gas is passed through the
column the materials are partitioned between the gas phase and the
stationary phase. Brooks (197H) points out that this separation is
similar to fractional distillation and that the performance of the column
in separations can be defined in terms of theoretical plate content (n)
by the equation
n = l6(Rt/W)2
where Rt = retention time (distance between solvent peak and
sample peak, expressed as time).
W = sample peak base width, expressed as time.
The materials used to carry the stationary phases are by no means always
inert and usually must be treated in various ways to remove reactive
centers which may decompose the samples. Many methods have been reported
for the preparation of column-packing materials, and a large number of
stationary phases suitable for various situations in organochlorine
pesticide analysis have been described in the pesticide literature.
Retention time is the principal parameter used to discriminate between
compounds, and tabulations have been compiled for various stationary
phases, most commonly referenced to aldrin (R. = 1.000). (Burke, 1966;
Pesticide Analytical Manual, Vol. I). Both TCepone and mirex have long
retention times relative to aldrin, approximately 2.7 for Kepone, and
5.0 for mirex; very few pesticides have longer retention times than mirex.
Since about 1960, with the development of the microcoulometric
detector by Coulson and the electron-capture detector by Goodwin, GC has
achieved both sensitivity and selectivity for organochlorine compounds
(Brooks, 197M).
Accurate analyses with GC critically depend on careful techniques
and rigid control of operating parameters. Sample solutions must be
cleaned up (i.e., separated from coextractives) sufficiently to permit
identification and measurement of residues and to prevent contamination
or destruction of any part of the GC system. The column and/or the
detector may be impaired by the injection of insufficiently cleaned-up
26
-------
samples, especially when the method and the gas chromatograph are being
used repeatedly. (Pesticide Analytical Manual, Vol. I).
Cleanup for the AOAC (Association of Official Analytical Chemists)
methods, detailed in the Pesticide Analytical Manual, is based, in
general, upon extraction of pesticides from a sample of non-fatty
substrates by acetonitrile or water-acetonitrile (preceded by a petroleum
ether extraction for fatty or oily samples). The extracted sample is
transferred to a dry hydrocarbon solvent e.g., petroleum ether, and is
isolated from coextracted substances by chromatography on a Florisil
column. The Florisil column is eluted with mixed petroleum and ethyl
ethers or with a methylene chloride: hexane: acetonitrile system. These
procedures are effective in removing normal contaminating substances from
samples prior to GC analysis.
However, one serious prjpb^sm with mirex determination by GC is the
interferfence of Arochlor 1260 , which has a peak almost overlapping the
mirex peak. Special sample cleanup procedures are required to eliminate
this interference (Markin, et al., 1972). Arochlor 125*1 also interferes.
Polychlorinated biphenyls have been, up to now, very widely used
chemicals. Their large-scale manufacture, about 275 million kg (600
million Ib), in the U.S. between 1960 and 1970 has resulted in the
inadvertent introduction of enormous amounts of PCB's into the
environment (Su and Price, 1973)- Reynolds (1969) noted that this was
evidently first detected by Jensen in wildlife tissues in Sweden in 1966.
Since then, PCB's have been found in wildlife and humans in most of the
industrialized areas of the world (Su and Price, 1973), and the presence
of PCB is a possibility in almost any environmental sample being analyzed
for an organochlorine pesticide.
Since there are about 210 PCB isomers, with varying boiling points
and GC retention times, they can interfere in the GC determination of
virtually all organochlorine pesticides. This problem has given rise to
much controversy in pesticide analysis, and may be the principal reason
for the difficulty in recognizing PCB's as environmental contaminants (Su
and Price, 1973).
The standard Florisil cleanup procedure does not effectively remove
interfering PCB's and additional cleanup and separation procedures are
required. Most depend on the use of a silicic acid column following the
Florisil colummn (Armour and Burke, 1970: Biros, et al., 1971); Snyder
and Reinert (1971) used a silica gel column directly on hexane extracts.
Markin, et al., (1972) recommend a modification of Armour and Burke's
•Arochlor is the tradename of a series of polychlorinated biphenyls
formerly manufactured by the Monsanto Chemical Company. Their
manufacture in the U.S. has recently be terminated.
27
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EXTRACTION
(20 gram sample in 100 ml
3:1 Hexane-lsopropanol)
Recovery of Mirex, DDT and
Metabolites, PCB's, Chlordane,
Heptachlor, and Heptachlor
Epoxide
Cleanup
Recovery of Mirex plus all
Other Pesticides, including
Aldrin, Dieldrin, Endrin,
and Organophosphorus
Compounds
Sulfuric Acid Wash (Con.
H2S04)
Acetonitrile Partitioning
Equal Vols 0-13 CN—Hexane
Florisil Cleanup
(PR Grade Unactivated)
5% Eluate
100 ml Methylene
Chloride
100% Eluate
100 ml Methylene
Chloride
Concentration
2.5ml = 5g
Concentration
2.5 ml = 5 g
GLC
Analysis
GLC
Analysis
Confirmation
Silicic Acid
Column
1 1
1st 100mlPet.-Ether
(Mirex 100%)
2nd 1 50 ml Pet.-Ether
(PCB)
200 ml eluting mixture
(1% CH3CN-1 9% Hex-80%
Methylene chloride)
(Other Pesticides)
I i
GLC
Analysis
Figure 2.5 Generalized analytical procedure flow diagram for mirex in
biological samples. Adapted from Markin, et al, (1972).
28
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method developed by Gaul and Cruz-La Grange (1971), which elutes mirex in
the first silicic acid column fraction, PCB's in the second, and the
remaining chlorinated hydrocarbon pesticides in the last
(acetonitrile:hexane:methylene chloride) eluate. The generalized scheme
used by Markin, et al., (1972) for biological samples, including the
silicic acid cleanup, is illustrated in Figure 2.5. Porter and Burke
(1973) proposed the use of unactivated Florisil followed by
chromatography on an activated Florisil column (methylene chloride :hexane
eluant). Bong (1975) has suggested a similar method.
Since it is not always evident in the literature on the analysis of
environmental samples for mirex whether or not the possibility of PCB
interference was recognized and compensated for, it should be recognized
that possibilities for error exist. Markin, et al., (1972) noted that two
possible cases of mistaken identity have appeared in the literature, in
which mirex reported in seafood could have been either PCB's or
Dechlorane.
PCB's can be eliminated by additional sample cleanup with methods
such as those described above, but since Dechlorane is chemically
identical with mirex, no unequivocal differentiation between the two is
possible. Presumptive differentiation can be made on the basis of other
evidence and deductive reasoning. The reported detection of C1QC115 in
the Great Lakes and in Great Lakes biota (e.g., fish and herring gufls)
almost certainly resulted from the manufacture of mirex or Dechlorane and
not from the fire ant control program in the southeastern U.S. (see
Section 2.5.1.2). Similarly, the reported detection of mirex in the
marine environment on the Pacific Coast is suspect, since it had no
important application in that area, and was not reported to have been
used there at all prior to 1971. Markin, et al., (1972) suggest that
PCB's or Dechlorane are the cause of these reported mirex findings.
Lewis, et al., (1976) have described an alternative method for the
determination of mirex in the presence of PCB's. The procedure depends on
diethylamine—or triethylamine-assisted photodegradation of interfering
PCB's prior to measurement of the mirex by electron-capture gas
chromatography. A 275-W sunlamp with spectral output greater than 280 nm
may be used as the irradiation source. Reductive dechlorination of the
PCB apparently results through primary photoexcitation of the biphenyl,
followed by hydrogen abstraction from the alkyl and amino groups of the
amine. The method has been successfully applied to human tissue extracts
for the presence of Arochlor 1260 and other commonly occurring
pesticides, including dieldrin, heptachlorepoxide and DDT.
The same general GC procedures applicable to mirex are also
applicable to the determination of Kepone; no mention has been observed
in the literature of specific PCB interferences with Kepone analysis.
29
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2.4.1.2 Thin-Layer Chromatography—
TLC is the method of choice for qualitative confirmation of
chlorinated pesticide assays by gas chromatography and may be used as a
semi-quantitative method of analysis if GC is not available. The methods
and techniques of TLC have been proven reliable, reproducible, and rapid,
and give results which can be reported semi-quantitatively (Pesticide
Analytical Manual, Vol. I).
TLC involves partitioning of substances on thin layers of silica gel
or alumina on plates of metal or glass. Cleaned up sample extracts and
reference organochlorine pesticide standards are spotted on coated plates
and developed with appropriate organic solvents. They are then visualized
by exposing silver nitrate-sprayed plates under UV light. The Pesticide
Analytical Manual indicates that the use of silica gel has been
discontinued for routine thin-layer chromatography of chlorinated
pesticides, as aluminum oxide possesses superior sensitivity.
2.4.1.3 Mass Spectrometry—
In his thorough discussion of chlorinated insecticides Brooks (1974)
noted that GC separation with mass spectrometric examination of the
separated fractions is undoubtedly the most valuable combination
currently available to the residue analyst or toxicologist attempting to
identify minute traces of organochlorine or other pesticides. In some
cases, the mass spectrometer is able to provide analytical data from
sample peaks not many orders of magnitude greater than the limits of
comfortable detection afforded by the most sensitive GC-electron capture
combinations. Recent publications on organochlorine compounds,
particularly environmental studies, usually contain data on mass spectral
fragmentation patterns. The techniques have been especially valuable for
identifying some of the molecular rearrangement products of cyclodiene
molecules.
Mass spectrometry is appropriately used when other analytical
methods of adequate sensitivity and specificity are not available. Mass
spectrometry, particularly in combination with gas chromatography (GC-MS)
and isotope-labelled internal standards, can form the basis of a
definitive quantitative assay for validating other assays. However, the
disadvantage of GC-MS is that sample throughput is relatively slow, and
that the system is difficult to fully automate (Foltz, 1977).
Since the large amount of data generated in a typical GC-MS analysis
are difficult to manipulate the present trend is to couple GC-MS with a
computer. Computer-based GC-MS analyses can be grouped into two
categories: repetitive scanning or selected ion monitoring. In the
former, the mass analyzer repetitively scans over the mass range of
interest. Upon completion of the run, the computer reconstructs a total
ionization chromatogram (TIC) by plotting the summation of ion
intensities for each scan number. The plot is similar in appearance to a
normal gas chromatogram and is .designated a computer-reconstructed gas
30
-------
chromatogram (RGC). Its primary use is to indicate which scans contain
mass spectral data corresponding to each component of interest. Selected
ion monitoring, plotting the ion current at selected masses versus time
or spectrum number, enables the mass spectrometer to be used as an
extremely selective and sensitive detector (Foltz, 1977).
Both of these techniques are quite useful in confirming the presence
of mirex and Kepone determined by gas chromatography. Perhaps even more
valuable is their capability for determining molecular structures of the
complex degradation products resulting from environmental exposure.
2.4.2 Analytical Considerations
The importance of removing PCB's before GC analysis for mirex has
already been discussed. Inadvertent sample contamination with
chlorine-containing compounds must be avoided, thus, metal cans rather
than plastic bags are preferred for storage of soil samples. Samples not
to be analyzed immediately, especially biota samples, are generally kept
frozen until analysis. Reagents and solvents used in GC analysis must
also be free of chlorine contaminants; and distilled-in-glass solvents
are generally recommended.
Residues of mirex detected in the environment may be as low as 1 ppt
in water, 1 ppb in soil, and 0.01 to 0.1 ppm in most animals. Thus,
exceeding care must be taken throughout the handling and analysis of such
samples to avoid biasing the results from artifacts.
No mention in the literature on PCB interference with Kepone
analysis has been noted; when electron capture GC analysis is being
employed, chlorine contamination of the sample must be avoided.
2.5 MANUFACTURE AND USE
2.5.1 Mirex
2.5.1.1 Manufactu re—
Official statistics on the annual production of mirex are not
available. All of the mirex produced in the U.S. is believed to be
manufactured or distributed by the Hooker Chemicals and Plastics
Corporation, Niagara Falls, New York (Markin, et al., 1972; Shapley,
1971). For a number of years, the same compound was sold by Hooker for
nonagricultural uses under the name Dechlorane. The principal use was as
a flame retardant for polymeric materials. Hooker still manufactures a
line of products called "Dechloranes" , but these are not C10C112
(Chambers, 1976). However, many of these current Dechlorane products also
appear to be highly chlorinated diene-type compounds possessing many
similarities to C^Cl.g.
From 1959 to June, 1967, Hooker produced the chemical C.QC112, and
ground, packaged, and sold the finished product. The material was^ made
31
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and handled exclusively at the Hooker plant at Niagara Falls, New York.
Beginning in June, 1967, Hooker purchased the material from other
producers, but continued to grind, repackage, and sell the material.
Sources of purchased material were Hexagon Laboratories, New York, New
York (22,680 kg in 1966), and the Nease Chemical Company, State College,
Pennsylvania, and Salem, Ohio (113,400 kg in 1966; 324,430 kg in 1968-69;
and 250,000 kg in 1973-74). (Chambers, 1976).
Total production data are not available. Sales data for 1959-1975,
separated into mirex and C10C112 sales, have been reported by Hooker to
EPA (Table 2.3). As shown by tnis tabulation, nearly three-quarters of
the C.-C1 _ sold was used for nonagricultural purposes during this
17-year period; mirex represented only about one-quarter of the sales.
The principal nonagricultural use of C,QC1.. was to impart flame
resistance to polymeric materials. As noted by Hutzlnger, et al., (1976)
most polymers, with the exception of those containing high percentages of
chlorine or fluorine, are relatively easily flammable. With increasingly
strict regulations on the flammability of clothing and home furnishings,
annual consumption of flame retardants can be expected to increase.
Hutzinger, et al., (1973) quote one estimate of 20,000 to 40,000 tons by
1980.
Some of the reactive type flame retardants can be incorporated into
the polymer, either by copolymerization or by chemical reaction with a
reactive group of the polymer, e.g., chlorendic anhydride, and
2,5-dibromoterephthalic acid (Hutzinger, et al., 1973). Dechlorane,
however, falls into the additive type, incorporated by physical blending
with the polymer. The halogenated fire-retardant additives such as
Dechlorane have some advantages over the chlorinated paraffins and
halogenated polyphenyls because they do not cause reductions in thermal
properties; in fact, the result is often an increase in the heat
resistance of the flame-retardant composition. Dechlorane, with a
chlorine content of 78 percent, and a melting point of 485 C, was one of
the first of these additives.
Such physically blended compounds would be expected to be more prone
to leaching or escape from the finished polymer product. Even
chemically-combined flame retardants would be susceptible to release upon
incineration, a common ultimate fate for many organic polymers. Thus,
additional investigation into the environmental fate of
Dechlorane-treated polymers appears to be needed, in view of its much
greater use than that of mirex, and especially because of the reports of
mirex in the environment in sections of the U.S. where mirex itself has
been employed only at a very minor level or not at all.
Data are unavailable on the total use of mirex as a pesticide in the
United States. However, compared with other chlorinated pesticides, mirex
was a small-volume pesticide. In 1972, a year for which estimates are
available for consumption of several other chlorinated pesticides (U.S.
Environmental Protection Agency, 1975), mirex sales compared as follows:
32
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TABLE 2.3 SALES OF
1959 - 1975C
Year
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
Total
Percent
Sales
As Mirex
—
—
90
5400
11,600
12,700
24,500
31,300
32,900
28,100
46,300
26,300
13,600
61,500
51,300
36,300
18,200
400,090
26.2
of C10C112, kg
For Nonagricultural Use
50
800
4000
35,900
129,200
210,000
245,700
150,200
72,300
126,300
32,800
20,700
37,200
54,400
-.-
1,300
4,600
1,125,450
73.8
Total
50
800
4.090
41,300
140,800
222,700
270,200
181,500
105,200
154,400
79,100
47,000
50,800
115,900
51,300
37,600
22,800
1,525,540
100.0
Source: Chambers (1976).
33
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Pesticide Metric Tons
Toxaphene 31,000 - 43,000
DDT 20,400
Aldrin 5,400
Mirex 61.5
2.5.1.2 Use—
The imported fire ant is generally believed to have first been
inadvertently introduced into the U.S. at the port of Mobile, Alabama, in
1918. It did not spread rapidly at first, but spread widely throughout
the southestern United States in the 1950's. The present distribution of
this pest is shown in Figure 2.6. The boundary of -6 to -12 C (10 to 20
F) minimum annual temperatures, which appears to prevent further
northward spread, is also shown. Although the West Coast of the U.S. is
presently free of the imported fire ant, annual temperatues there would
be conducive to its spread to that area.
In areas where the fire ant is established, a concentration of about
75 to 100 mounds per hectare (30 to 40 per acre) is usual. The mounds
range in size from those that are barely visible to mounds that might be
1 m in diameter and almost 1 m tall. When the mound of an established
colony is disturbed, thousands of ants pour out, seeking their attacker.
(Alley, 1973).
The Federal government and the states began their effort to combat
the fire ant in 1957, initially by spraying dieldrln at a rate of 2.24
kg/ha (2 Ib/ac). Heptachlor at a rate of 1.12 to 1.25 kg/ha (1.00 to 1.25
Ib/ac) was substituted in 1958; this dosage was later reduced to two
applications at a rate of 0.28 kg/ha (0.25 Ib/ac), spaced 3 or 4 months
apart (Coon and Fleet, 1970).
In 1961, mirex was developed by the Allied Chemicals and Plastics
Corporation for control of several ant species. Following the development
of an effective bait, the first field test was made near Gulfport,
Mississippi, in the fall of 1961, (Markin, et al., 1972). Since that
date, mirex bait has totally supplanted the earlier insecticides for fire
ant control by area application because of its superior effectiveness and
its drastically lower rates of application to the environment.
The mirex bait used for fire ant control consists of ground corn cob
grit (85 percent), once-refined soybean oil (approximately 15 percent),
and technical grade mirex at a few tenths percent. The mirex is dissolved
in the soybean oil and then added to the corn cob grits. The corn cob
grits are similar to coffee grounds in size and consistency, and when
applied correctly, approximately 170 to 320 granules are deposited on
each square meter of land (Markin, et al., 1972).
The common bait formulations originally used were designated 4X and
2X. The 4X bait contained 0.3 percent mirex, and was generally used for
aerial application, at the rate of 1.4 kg/hectare (1.25 lb bait/ac). At
34
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to
V/l
INFESTED AREA
O INCIPIENT INFESTATION
N.x" BOUNDARY OF 10*-2Cf
WIN. TEMP. AREAS
Figure 2.6 Fire ant distribution, 1976.
Source: Council for Agricultural Science and
Technology (1976).
-------
this rate, actual mass of mlrex applied was only 4.2 g/ha (1.7 g/ac). The
2X bait contained 0.15 percent mirex and was the form generally sold to
home owners for individual use. It has also been applied aerially at 5.6
kg/ha (5 Ib/ac) which deposits 8.4 g/ha (3.4 g/ac) of active ingredient.
A new formulation, designated 10:5, has supplanted 2X bait. It also
contains 0.15 percent mirex, but is prepared by adding 2/3 of the soybean
oil, undosed, to the corn cob grits, and allowing the mixture to
equilibrate a few days before adding the other 1/3 of the soybean oil,
which contains all of the mirex. The theory is that by pre-loading the
corn cob grits with plain soybean oil, the dosed oil will tend to remain
on the surface; thus more of the mirex can be effective against the ants.
The 1977 program used a 0.1 percent bait at a rate of 2.5 kg/ha (1
Ib/ac), equivalent to 0.45 g active ingredient per acre. Experimental
degradable baits containing 0.05 and 0.025 percent mirex applied at 2.5
kg/ha (1 Ib/acre) deposit only 0.23 and 0.11 g of mirex per acre.
In another variation of mirex bait formulation, the carrier is a
material called "Furag", the partially carbonized corn cob residue
remaining after corncobs are treated with sulfuric acid in the
manufacture of furfural. Since the grits are somewhat smaller, and more
friable, they can be utilized more effectively as bait (Brown, 1977).
When an infested area is treated with mirex bait, the bait is
rapidly scavenged by the fire ant workers and placed in the mound. The
toxicant is distributed throughout the colony, including the queen and
brood, before any toxic effects become evident. Several weeks later, the
ants die. This delayed toxicity is important because it allows sufficient
time for distribution of the toxicant throughout the colony (Alley,
1973). In a few days the bait tends to become rancid, and less attractive
to the ants. Also, since it leaves no effective residue, reinfestation
into small cleared areas is quite rapid. Thus, its use by homeowners has
been slow to gain acceptance; most homeowners preferred to use persistent
pesticides, such as heptachlor, chlordane, or dieldrin (when these
products were available) because they produced a rapid kill and left a
residue to prevent reinfestation (Markin, et al., 1972).
After the successful 1961 field tests, programs against the imported
fire ant using the newly developed mirex-corncob bait were begun in 1962.
A Federal-State cooperative program was conducted by the U.S. Department
of Agriculture until 1975. For the first several years, between 1962 to
1965, mirex (active ingredient) was applied at the rate of 8.4 g/ha (3.4
g/ac); from 1966 on, the rate was 4.2 g/ha (1.7 g/ac). Areas covered in
10 states and calculated mirex consumptions are summarized in Table 2.4
for FY 1962 to 1973. These data include only the mirex applied through
the Federal-State cooperative program; they do not include areas treated
by states independently, nor do they include the small-package
over-the-counter sales made by many states to farmers, generally at cost,
for individual application and spot treatment of mounds. While data are
not available for the entire 1962 to 1975 period, data presented by
Markin, et al., (1972) for 10 years (1962 to 1971) are illustrative.
36
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TABLE 2.4. AGGREGATE AREAS TREATED WITH MIREX UNDER FEDERAL-STATE COOPERATIVE PROGRAM, FY 1962-19733
Areas Treated. Acres
1962
1963
1964
1965
Alabama
46,370
100,920
78,110
117,050
Arkansas
21,790
4,000
25,290
32,500
Florida
1,340
16,220
90,440
167,190
Georgia
2j_
477,310
727,900
970,450
742,700
Louisiana Mississippi
5 Ib bait/acre
263 ,440
567,230
441,750
1,050,150
1.25 Ib bait/acre
1966
1967
1968
1969
1970
1971
1972
1973
Total
Total
294,210
899,800
326,580
275,230
285,590
198,540
354,050
1.426,840
4,403,290
61,910
34,500
20,290
35,660
162,450
44,260
0
52.040
494,690
961,160
968,150
3,388,700
2,610,650
204,830 c
0
99,460 c
0(0
8,508,140
mlrex applied: 1962-65 30,095
1966-73 155.885
Total, 1962-73 185,980
2,039,780
1,994,590
5,530,900
5,267,040
8,557,390
6,626,080
5,615,680
7.251.940
45,801,760
kg ( 66,350
kz (343.670
(410,020
1,335,510
2,820,930 2
439,900 1
943,530
1,642,220
744,390 3
1,100,000 3
1.770.190 2
13,119,240 17
Ib)
Ib)
Ib)
b
North
•Carolina
South
Carolina
Tennessee
Texas
Total
(3.4 R mirex/acre)
79,050
340,620
232,030
658,320
7,000
29,760
144,590
56,900
37,540
26,340
324,120
581,110
0
0
0
0
40,260
45,000
40,910
266,120
974,100
1,857,990
2,347,690
3.672.040
8,851,820
(1.7 K mirex/acre)
963,800
,794,500
,650,810
859,590
515,150
,183,450
,326,160
.717.730
,321,210
232,660
224,990
77,650
75,420
60,320
80
1,580
0
910,950
36,430
36,840
1,353,900
766,020
2,951,540
799,150
565,810
362.740
7,841,540
0
32,980
0
0
0
0
0
0
Subtotal
32,980 2,
203,090
439,580
44,460
288,390
124,030
13,910 c
2,380 c
602.540 c
115,670
6,128,550
10,246,860
12,833,190
11,121,530
14,508,520
11,609,770
11,065,120
14.184.020
91,697,560
100,549,380
aSource: U. S. Department of Agriculture (1977).
Acre • 0.405 hectare.
°Extensive treatment performed under independent state program.
-------
During this period, the records indicate that a total of 122,260 kg of
mirex was applied, of which only 4,280 kg (3.5 percent) was credited to
State-farmer programs, i.e., 96.5 percent of the total was applied under
the Federal Cooperative Program. Since evidence from the infested
southeastern states indicates that this ratio is also representative of
the next several years, it seems certain that over-the-counter sales were
a very minor segment of mirex consumption.
Two states, Florida and Texas, had significant state programs,
independent of the Federal-State cooperative program. From 1970 on,
Florida's participation in the U.S.D.A. program was impeded by
application restrictions, including a requirement of minimum treatment
blocks of 2,050 hectares (5,000 acres). Since assembly of blocks of this
size posed problems in Florida, more reliance was placed on the Florida
state program, which included both aerial and ground application. From
1970 to February, 1975, approximately 2,500 kg of mirex was applied under
this program (Brown, 1977). Similarly, the state of Texas, over the past
4 to 5 years, has treated several million acres with mirex bait; this
might account for several thousand additional kilograms of mirex (Ivie,
1977). Except for these two states, use of mirex for fire ant control by
other southeastern states was quite minor.
In addition to the imported fire ant, several other species of
locally important U.S. pests are effectively controlled by the use of
mirex applied as bait formulations; these include the western harvester
ant, Pogonomyrmex occidentalis, which infests millions of hectares of
rangeland of the western states, and the Texas leaf-cutting ant, Atta
texana, a serious pest of pine seedlings, hardwood trees and cereal and
forage crops in some areas of east Texas and west central Louisiana.
Mirex is one of the best control materials for the Texas leaf cutting
ant, and is used commercially to protect timber areas, but it is a low
volume usage (Ivie, 1977). No quantitative data on mirex usage for these
other ant pests has been identified, but indications are that such use
was also minor (Ivie, 1977). Mirex baits were also registered by Allied
Chemical Company for yellow jacket control at one time, but no data on
the magnitude of this use was found.
Beginning in 1970, mirex was also used in Hawaii to control
populations of the big-headed ant (Pheidole megacephala) in pineapple
fields (Bevenue, et al., 1975). This ant has a symbiotic relationship
with the pineapple mealybug which transmits mealybug wilt, a serious
pineapple disease. Control of the ant population keeps the disease in
check (Johnson, et al., 1976). In 1972 about 3^,500 kg (76,000 Ib) of
bait was used to treat 12,150 hectares (30,000 acres). Total active mirex
was only about 100 kg. The use of mirex in Hawaii was temporarily
suspended in 1972 by EPA, but the suspension was later stayed on
condition that a one year monitoring program, approved by EPA, be
conducted. In 1973, the stay was again continued, providing that a
further mirex monitoring program would be carried out (Johnson, et al.,
38
-------
1976). These Hawaiian monitoring programs provided quantitative data on
the fate of mi rex in the environment; these data are described later
(Section 7.2.2).
The total quantity of mirex represented by the 1962-73 Federal-State
cooperative program summarized in Table 2.4 is approximately 186,000 kg
(410,000 Ib). During the same period, the sales of mirex by Hooker
Chemicals and Plastics Corporation (Table 2.5) totalled approximately
345,000 kg (760,000 Ib). As shown above, neither the State-farmer
programs nor independent State fire ant control programs account for the
difference of 159,000 kg, nor is there evidence that significant
quantities were used for the control of other U.S. pests. Thus, it is
concluded that the Federal-State cooperative program accounts for most
(probably over 90 percent) of the mirex used as a pesticide in the U.S.
It is believed that most of the difference between the amounts of mirex
sold and the amounts applied can be attributed to export sales. Markin,
et al., (1972) noted that an unknown amount is produced and shipped
abroad for the control of other ants, particularly the leaf cutter ant in
South America. In addition, it may be used in Brazil for control of the
native fire ant. For example, Hooker records show that one-fourth
(approximately 4,600 kg) of 1975 mirex sales was destined for Brazil.
Further, 40,600 kg of the total stock of 174,200 kg remaining on hand as
of May, 1976, was on consignment to Brazil (Hooker Chemicals and Plastics
Corporation, 1976).
The registration for 4X mirex bait was cancelled, effective December
1, 1976, and use of existing stocks permitted only through December 31»
1976. The registration for 10:5 bait was cancelled, effective December 1,
1977; aerial application of existing stocks was permitted through
December 31, 1977- Bait existing December 1, 1977 could be packaged and
sold in 5-lb bags for ground application until June 30, 1978. The
cancellations also specified that no more than 27,200 kg (60,000 Ib) of
technical mirex could be used for the two baits during this phase-down
period. (U.S. Environmental Protection Agency, 1976b).
Overall, it appears clear that the total quantity of mirex applied
for control of the fire ant in the U.S. through 1975 was something under
400,000 kg, probably about 250,000 kg. Usage during the phase down period
may. increase total usage to 275,000 kg.
2.5.2 Kepone
2.5.2.1 Manufacture—
Kepone was developed by the Allied Chemical Corporation in the early
1950's; original patents were granted in 1952 (Kelly, 1976a). As
indicated in Section 2.2, the commercial manufacturing process was based
on reacting hexachlorocyelopentadiene with SO-, with subsequent
hydrolysis to form Kepone.
39
-------
The procedure used for the early manufacture of Kepone at the Allied
Chemical Corporation semi works plant at Hopewell, Virginia, is described
in an Allied Research Informal Memorandum appended to an EPA report
attempting to estimate Kepone discharges from the Allied plant (Smith,
1976). In this preparation procedure, 3442 kg (7,590 Ibs) of hex was
charged to a reactor, to which waa added 11.3 kg (25 Ibs) of antimony
chloride catalyst, a small quantity of water (700 g), and 1,513 kg (3,336
Ib) of sulfur trioxide (50 percent excess). The mixture was heated to 85
to 90 C for 10 to 12 hours. The reaction mass was quenched in 6 percent
aqueous sodium hydroxide solution to hydrolyze it and put it into
solution. The solution was neutralized with sulfurlc acid to a pH of 5 to
6 to precipitate the Kepone. After digestion and cooling, the Kepone was
centrifuged and washed with warm water to remove sodium sulfate, sodium
chloride, and excess sulfuric acid, and was then dried. The average yield
of the finished product was 2,517 kg (5,500 Ib), containing 5.2 percent
water. On the basis of hex charged, yield was 81 percent. Washings were
discharged to the sewer. On the basis of a Kepone solubility of A/2 ppm
and the volumes of aqueous discharges, they were calculated to contain
from 40 to 80 g of soluble Kepone per day of operation (Smith, 1976).
No discussion of the fate of the approximately 20 percent of hex not
forming Kepone has been found in the literature. Since the solubility of
hex is, like that of Kepone, quite low (0.81 ppm according to Lu, et al.,
1975), the soluble losses of unreacted hex should have been negligible.
However, under the reaction conditions employed, attack by the SO. could
well have resulted In sufonation and sulfation of the hex to form Various
water-soluble by-products.
For a number of years after its development, Kepone production was
limited, with Allied and two subcontractors manufacturing it only
sporadically. On the basis of receipt records at the Allied Chemical's
formulating and shipping plant at Baltimore, Maryland, technical Kepone
was initially received in 1951 from Allied Chemical's development
laboratories (1,360 kg). No more was received until 1959, when the Nease
Chemical Company, State College, Pennsylvania, supplied 5,680 kg (12,530
Ib), Nease Chemical also supplied small amounts in 1962 and 1963, and the
Hooker Chemicals and Plastics Corporation, Niagara Palls, New York, was a
supplier in 1965. (Allied also accepted 6,230 kg of residual inventory of
off-specif!cation material from Hooker in 1967 (Ferguson, 1975).
Demand began to grow in the late 1960's, as banana pests started to
develop immunity to some widely used pesticides, and Allied itself took
over production at its semi works plant located at the Hopewell, Virginia,
chemical complex (Bray 1975). Allied Chemical reportedly produced from
680 to 1,130 kg/day (1,500 to 2,500 Ibs/day) intermittently at the
semiworks, during the period from 1966 to 1974 (Kelly, 1976b). Kepone was
produced only as needed, and production runs seldom lasted more than 90
days at a time (Bray, 1975). Increasing demand for the pesticide,
particularly from Europe, and a need for the semiworks facility for the
manufacture of other chemicals evidently led to the transfer of
manufacture to the Life Sciences Products Company (LSPC) of Hopewell,
1*0
-------
Virginia, beginning In early 1974 (Kelly, 1976b; Jaeger, 1976).
Production continued to increase, exceeding 385,000 kg (840,000 lb) in
1974. During the first six months of 1975 preceding the closing of the
LSPC plant over 384,000 kg (846,000 lb) were produced. Total receipts of
technical Kepone at Allied'a Baltimore formulating plant, as compiled by
Ferguson (1975), are shown in Table 2.5.
Total production, using Ferguson's compilation, was nearly 1,600,000
kg (3,500,000 lb). Very little of this was used in the United States. One
EPA estimate (U.S. Environmental Protection Agency, 1975b) was that 99.2
percent of annual production was exported to Latin America, Africa, and
Europe. Another report (Sterrett and Boss, 1977) states that over 90
percent of the nearly 770,000 kg (1,700,000 lb) manufactured by LSPC was
exported to these same areas for control of insect pests,
2.4.2.2 Use-
There are no large scale agricultural uses for Kepone in the U.S.;
most of the moderate to small annual U.S. consumption appears to have
been for domestic roach and ant control. Most of the Kepone produced was
shipped overseas to a West German firm for conversion into other
pesticide products (Kelly, 1976b),
One of Kepone1s principal uses is for control of the banana root
borer. A 5 percent dust is registered for use in Puerto Rico on banana
plants. Directions call for surface application of 3.6 kg/ha (8 Ib/ac) of
active ingredient, and allow for application at six month Intervals (U.S.
Environmental Protection Agency, 1976c), In an earlier document (U.S.
Environmental Protection Agency, 1975b), the dosage was given as 2.2
kg/ha (2 Ib/ac) or 2.8 g (0.1 oz) per plant,
*
This constitutes the only known use of Kepone on food crops. On
non-food crops, Kepone has been used for control of wire worms in tobacco
fields, and in bait and traps to control ants and roaches in indoor and
outdoor areas. (U.S. Environmental Protection Agency, 1975b). According
to the notices of Rebuttable Presumption Against Registration and
Continued Registration (U.S. Environmental Protection Agency, 1976d,e)
there were at that time 27 companies manufacturing roach or ant traps or
baits. Active ingredients were limited to 0.125 percent Kepone.
•Revocation of the tolerance, or maximum residue level, of 0.01 ppm in
or on bananas has been promulgated by EPA (U.S. Environmental
Protection Agency, 1978) at the request of the only registrant. This
will essentially eliminate its use on bananas.
-------
TABLE 2.5 RECEIPTS OF TECHNICAL KEPONE AT BALTIMORE, MARYLAND
FORMULATING PLANT OF ALLIED CHEMICAL CORPORATIONa
Year
1951
1952-58
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
Total
Quantity
kg (Ib)
1,360
None
5,710
4,990
None
1,430
18,125
5,550
None
16,270
1,035
35,435
6,260
47,990
36,535
46,990
41,460
204,800
176,970
100,435
72,260
385,370
384,020
1,592,895
(3000)
Reported
(12,530)
(11,000)
Reported
(3,150)
(39,960)
(12,245)
Reported
(35,880)
(2,285)
(78,125)
(13,800)b
(105,800)
(80,550)
(103,600)
(91,400)
(451,515)
(390,150)
(221,425)
(159,300)
(849,600)
(846,625)°
(3,511,940)
Source
Allied Development Laboratory
Nease Chemical Company
Nease Chemical Company
B&A Works
Nease Chemical Company
B&A Works
Hooker Chemical and Plastics Corp
Nease Chemical Company
Allied /Hopewell
Hooker Chemical and Plastics Corp
Allied/Hopewell
Life Science Products Company
Life Science Products Company
aSource: Ferguson (1975).
b Off-specification residual Hooker inventory.
c Through July, 1975.
-------
2.6 REFERENCES
Alley, E.G. 1973- The Use of Mirex in Control of the Imported Fire Ant.
J. of Environmental Qual. 2 (1): 52-61.
Alley, E.G., D. A. Dollar, B. R. Layton, and J. P. Minyard, Jr. 1973.
Photochemistry of Mirex. J. Ag. and Food Chem., 21 (1): 138-139.
Alley, E. G., B. R. Layton, and J. P- Minyard, Jr. 1974a. Identification
of the Photoproducts of the Insecticides Mirex and Kepone. J. of Ag.
and Food Chem., 22 (3): 442-444.
Alley, E. G., B. R. Layton, and J. P. Minyard, Jr. 1974b. Photoreduction
of Mirex in Alphatic Amines. J. of Ag. and Food Chem. 22 (4):
727-729.
Alley, E. G. 1977- Personal communication.
Allied Chemical Corporation. 1958a. Development Information Bulletin.
6-58 Kepone (Insecticide-Fungicide). General Chemical Division,
Allied Chemical Corporation.
Allied Chemical Corporation. 1958b. Letter from M. Darley, April 15, 1958
to W. F. Huber, Nease Chemical Company.
Armour, J. A. and J. A. Burke. 1970. Method for Separating Polychlorinatd
Biphenyls from DDT and Its Analogs. J. Assoc. of Official Anal.
Chem., 53 (4): 761-768.
Bevenue, A., J. N. Dgata, L.S. Tengan, and J. W. Hylin. 1975. Mirex
Residues in Wildlife and Soils, Hawaiian Pineapple-Growing Areas -
1972-74. Pesticides Monitoring J. 9(3):141-149.
Biros, F. J., A. C. Walker, and A. Medbery. 1970. Polychlorinated
Biphenyls in Human Adipose Tissue. Bull, of Environmental Contain.
and Toxicol., 8 (4): 317-323-
Bong, R. L. 1975. Determination of Hexachlorobenzene and Mirex in Fatty
Products. J. Assoc. of Official Anal. Chem., 58 (3): 557-561.
Bray, T. J. 1975. Health Hazard—Chemical Firm's Story Underscores
Problems of Cleaning Up Plants. Wall Street Journal, December 2,
1975.
-------
Brooks, G. T. 1974. Chlorinated Insecticides. Volume I. Cleveland CRC
Press, Inc., pp. 129, 143-144, 170, 174.
Brown, R. 1977. Personal communication.
Burke, J. A., and W. Holswade. 1966. A Gas Chromatographic Column for
Pesticide Residue Analysis: Retention Times and Response Data. J.
Assoc. of Official Anal. Chem., 49 (2): 374-385-
Carnes, R.A. 1977a. Thermal Degradation of Kepone. Municipal
Environmental Research Laboratory, U.S. Environmental Protection
Agency, Cincinnati, Ohio. February 15, 1977-
Carnes, R. A. 1977b. Personal communication.
Carlson, D. A., K. D. Konyha, W. B. Wheeler, G. P.Marshall, and R. G.
Zaylskie. 1976. Mirex in the Environment: Its Degradation to Kepone
and Related Compounds. Science 194 (4268): 939-941.
Chambers, A. W. 1976. Information Pertaining to Product "Mirex". Letter
of May 21, 1976, from A. W. Chambers, Hooker Chemicals and Plastics
Corporation to Mr. G. A.Shanahan, Region II, U.S. Environmental
Protection Agency, New York, New York.
Coon, D. W., and R. R. Fleet. 1970. The Ant War. Environment 12 (10):
28-38.
Council for Agricultural Science and Technology. 1976. Fire Ant Control.
CAST Report No. 62. Iowa State University, Ames, Iowa, pp 28.
de la Cruz, A. A. and S. M. Naqvi. 1973. Mirex Incorporation in the
Environment: Uptake in Aquatic Organisms and Effects on the Rate of
Photosynthesis and Respiration. Arch, of Environmental Contain, and
Toxicol. 1 (3): 255-264.
Dilling, W. L., H. P. Braendlin, and E. T. McBee. 1967. Pentacyclodecane
Chemistry-II. Some Reactions of Dodecachloropentacyclo
5.3.0.0. .0^.0 ' Decane and Related Compounds.
Tetrahedron. 23: 1211-1224.
Duvall, D. S., and W. A. Ruby. 1976. Laboratory Evaluation of High-
Temperature Destruction of Kepone and Related Pesticides.
EPA-600/2-76-299. U.S. Environmental Protection Agency. 59 pp.
Eaton, P., E. Carlson, P. Lombardo, and P. Yates. 1960. Pyrolysis of the
Cage Ketone C1QC1100. J. Org. Chem. 25, 1225.
Ferguson, W. S. 1975. Letter of September 12, 1975, to S. R. Wasserug,
Enforcement Division, U.S. Environmental Protection Agency, Region
III, Philadelphia, Pennsylvania.
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Ferraro, T., and E.Roby. 1976. The Peril of Kepone Still Lingers.
Columbus, Ohio, Dispatch, August 1, 1976.
Finklestein, H. 1969. Air Pollution Aspects of Pesticides. APTD 69-41.
Litton Systems, Inc., Bethesda, Maryland. Department of Health,
Education, and Welfare, Consumer Protection and Environmental Health
Service, National Air Pollution Control Administration. PB-188091.
NTIS. 163 pp.
Foltz, R. L. 1977- Mass Spectrometry. In: Guidelines for Analytical
Toxicology Problems: Organization - Instrumentation - Techniques,
Thoma, J. J. and I. Sunshine (eds.). CRC Press, Inc., Cleveland,
Ohio.
Gaul, J., and P. C. LaGrange. 1977. U.S. Department of Health, Education,
and Welfare, Food and Drug Administration, New Orleans, Louisiana.
Private communication.
Gawaad, A.A.A.-W., M. A. Hamad and F. H. El-Gayar. 1971. Effect of the
Canal Irrigation System Used in the Persistence of Soil
Insecticides. International Pest Control 13 (4): 8-10, 28. Health
Aspects of Pesticides Abstracts 5(4): 72-0686-90 .
Gibson, J. R., G. W. Ivie, and H. W. Dorough. 1972. Fate of Mirex and Its
Major Photodecomposition Product in Rats. J. of Ag. and Food Chem.,
20 (6): 1246-1248.
Holden, C. 1976. Mirex: Persistent Pesticide on Its Way Out. Science. 194
(4262): 301-303-
Hollister, T. A., G. E. Walsh, and J. Forester. 1975. Mirex and Marine
Unicellular Algae: Accumulation, Population Growth and Oxygen
Evolution. Bull. Environmental Contain, and Toxicol. 14, 6, 753-59-
Holloman, M. E., B. R. Layton, M. V. Kennedy, and C. R. Swanson. 1975.
Identification of the Major Thermal Degradation Products of the
Insecticide Mirex. J. of Ag. and Food Chem. 23 (5): 1011-1012.
Hutzinger, 0., and G. Sundstrom. 1976. Environmental Chemistry of Flame
Retardants. Part 1. Introduction and Principles. Chemosphere 5(1):
3-10.
Ivie, D. 1977- Personal communication.
Ivie, G. W., H. W. Dorough, and E. G. Alley. 1974. Photodecomposition of
Mirex on Silica Gel Chromatoplates Exposed to Natural and Artificial
Light. J. of Ag. and Food Chem., 22 (6): 933-935.
Jaeger, R. J. 1976. Kepone Chronology. Science 193 4248: 94-95.
45
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Johnson, J. M., A. M. Dollar, and D. C. Cox. 1976. Mirex Monitoring in
Hawaii - A Cooperative Venture. J. of Environmental Health 38 (4):
254-259-
Kecher, R. M., L.A. Evlamp'eva, M. B. Skibinskaya, and N. S. Zefirov.
1969. Polycyclic and Cage Compounds. Zh. Organ. Khim. 5 (4):
697-702.
Kelly, B. 1976a. The Invention of Kepone: It Looked Great on Paper.
Washington Star, September 21, 1976.
Kelly, B. 1976b. The Inside Story of a Kepone Plant, with Varying
Opinions. Washington Star, September 22, 1976.
Lane, R. H., R. M.Grodner, and J. L. Graves. 1976. Irradiation Studies
of Mallard Duck Eggs Material Continuing Mirex. J. of Ag. and Food
Chem. 24 (1): 192-193-
Lewis, R. G., R. C. Hanisch, K. E. MacLeod and G. W. Sorocool. 1976.
Photochemical Confirmation of Mirex in The Presence of
Polychlorinated Biphenyls. J. Agric. Food Chem. 24(5):1030-1035.
Lu, Po-Yung, R. L. Metcalf, A. S. Herive, and J. H. Williams. 1975.
Evaluation of Environmental Distribution and Fate of Hexachloro-
cyclopentadiene, Chlordene, Heptachlor, and Heptachlor Epoxide in
a Laboratory Model Ecosystem. J. Ag. Food Chem. 23, 6, pp 967-972.
Markin, G. P., J. H. Ford, J. C. Hawthorne, J. H. Spence, J. Davis, H. L.
Collins, and C. D. Loftis. 1972. The Insecticide Mirex and
Techniques for Its Monitoring. U.S. Department .of Agriculture,
Animal and Plant Health Inspection Service, Hyattsville, Maryland.
APHIS 81-3. 19 PP.
McBee, E. T., C. W. Roberts, D. J. Idol, R. H. Earle. 1956. An
Investigation of the Chlorocarbon CinCl19 and the Ketone C1QC1100
J. Amer. Chem. Soc. 78, 1511.
Mirex Advisory Committee. 1972. Report of the Mirex Advisory Committee
to William D. Ruckelshaus, Administrator, Environmental Protection
Agency, February 4, 1972. Unpublished Report. 72 pp.
Pattison, V. A. and R. R. Hindersinn. 1971- Halogenated Fire Retardants
In: Kirk-Othmer Encyclopedia of Chemical Technology. Supplement
Volume. Interscience Publishers, John Wiley and Sons, New York, N.
Y. pp 483-486.
Porter, M. L., and J. A. Burke. 1973. An Isolation and Cleanup
Procedure for Low Levels of Organochlorine Pesticide Residues in
Fats and Oils. J. of the Assoc. of Official Anal. Chem. 56 (3):
733-738.
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Reynolds, L. M. 1969. Polychlorobiphenyls (PCB's) and Their
Interference with Pesticide Residue Analysis. Bull, of
Environmental Contain, and Toxicol. 4 (3): 128-143.
Shapley, D. 1971. Mirex and the Fire Ant: Decline in Fortunes of
"Perfect" Pesticide. Science 172 (3981): 358-360.
Smith. 1976. Kepone Discharges from Allied Chemical Corporation,
Hopewell, Virginia. National Field Investigations Center, U.S.
Environmental Protection Agency, Denver, Colorado.
Snyder, D., and R. Reinert. 1971. Rapid Separation of Polychlorinated
Biphenyls from DDT and Its Analogues on Silica Gel. Bull, of
Environmental Contam. and Toxicol. 6 (5): 385-390.
Sterett, F. S. and C. A. Boss. 1977. Careless Kepone. Environment,
March, 1977- pp. 30-37.
Su, G.C.C., and H. A. Price. 1973- Element Specific Gas Chromatographic
Analysis of Organochlorine Pesticides in the Presence of PCB's by
Selective Cancellation of Interfering Peaks. J. of Ag. and Food
Chem. 21 (8): 1099-1102.
U.S. Department of Agriculture. 1977. Animal and Plant Health
Inspection Service, Personal communication from R. Cowden and R.
Williamson.
U.S. Department of Health, Education, and Welfare, Food and Drug
Administration. 1968 and Rev. Pesticide Analytical Manual. Vol. 1.
Methods Which Detect Multiple Residues. Vol. II. Methods for
Individual Pesticide Residues. U.S.Department of Health, Education
and Welfare, Food and Drug Administration. Rockville, Maryland.
Various pagination.
U.S. Department of Health, Education, and Welfare, Food and Drug
Administration. 1969. Kepone. In: Pesticide Analytical Manual.
Vol. II. Methods for Individual Pesticide Residues, Rockville,
Maryland, pp. 1, 1-2.
U.S. Departmment of Health, Education, and Welfare, Food and Drug
Administration. 1969. Mirex. In: Pesticide Analytical Manual. Vol.
II. Methods for Individual Pesticide Residues, Rockville,
Maryland, pp. 1, 1-5.
U.S. Environmental Protection Agency. 1975a. Determination of
Incinerator Operating Conditions Necessary for Safe Disposal of
Pesticides. EPA 600/2-75-041. Municipal Environmental Research
Laboratory, Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1975b. Kepone, A Summary Prepared
by the Criteria and Evaluation Division. EPA Internal Memo 7 pp.
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U.S. Environmental Protection Agency. 1976a. CBIB Analysis of Mirex
Samples. EPA Internal Memo, CBIB to Mr. T. Holloway, Office of
Pesticide Programs.
U.S. Environmental Protection Agency, 1976b. Administrator's Decision
to Accept Plan of Mississippi Authority and Order Suspending Hearing
for the Pesticide Mirex. Federal Register 41 (251): 56994-56704,
December 29.
U.S. Environmental Protection Agency. 1976c. CRPAR Checklist—Active
Ingredient. Chlordecone-Kepone. Acute Toxicity to Humans and
Domestic Animals. Does Chlordecone Meet or Exceed the Criteria for
Oncogenic Effects on Man or Other Mammals. Unidentified Source. 15
pp.
U. S. Environmental Protection Agency, Office of Pesticide Programs.
1976d. Kepone (Chlordecone). Notice of Presumption Against
Registration of Pesticide product. Federal Register 41 (59):
123334-12335.
U. S. Environmental Protection Agency, Office of Pesticide Programs.
1976de. Kepone (Chlordecone). Notice of Presumption Against
Continued Registration of Pesticide Product. Federal Register 41
(59): 12333-12334.
U. S. Environmental Protection Agency. 1978. Revocation of Tolerance
for Kepone. Federal Register 43 (19) 3708-3709. January 27.
Whetstone, R. R. 1964. Chlorinated Derivatives of Cyclopentadiene.
Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition.
Interscience Publishers, John Wiley and Sons, New York. 5:240-252.
Zijp, D.H., and H. Gerding. 1958. The Structure of the Compound
C1QC112 Reel. Trav. Chim. Pays-Bas 770: 682-691.
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3.0 EFFECTS ON MICROORGANISMS
3.1 SUMMARY
Laboratory investigations have shown that mirex in concentrations up
to 100 ppm did not inhibit hydrolysis of gelatin, starch, lipid, casein
or affect other metabolic functions of estuarine microorganisms.
Concentrations up to 1000 ppm of mirex did not significantly alter either
microbial populations or microbial activities in estuarine sediments.
Various degradation products of mirex, notably Kepone and reduced Kepone
may, however, be more toxic to microorganisms than the parent compounds,
because of their higher water solubility.
Mirex concentrations up to 20,000 ppm (1 gram mirex to 50 g soil)
had no effect on total populations of soil bacteria or fungi, but
actinomycete populations were reduced at 10,000 ppm in some soil types.
Degradation of mirex by soil microorganisms has not been observed in
either aerobic or anaerobic conditions. Sewage sludge microorganisms, on
the other hand, appear to be capable of metabolizing mirex under
anaerobic conditions, but the process is very slow.
Kepone applications of 22.0 kg/ha (19-6 Ib/acre) to three soil types
in the Nile Delta altered fungi, actinomycete and bacteria populations.
Disagreement exists concerning the reasons for population resurgence of
the microorganisms and the decline of the biological activity of Kepone.
Ammonification of peptone, decrease of nitrification of ammonium sulfate,
temporary accumulation of nitrites, and decrease of nitrates have been
observed in soils treated with Kepone. Elevated nitrite levels may be
toxic to some plant species.
Beneficial bacteria were reported kiled in sewage treatment
facilities at Hopewell, Virginia, upon the addition of Kepone wastes.
3.2 ESTUARINE MICROORGANISMS
Brown, et al., (1975) conducted a series of related experiments to
establish the chemical and microbiological fate of mirex in the estuarine
environment and to determine its effects on important estuarine
microorganisms and their activities. The most important results of this
study were: (1) At least 95 percent of mirex in aqueous solution is
removed by adsorption by organic matter (dead bacterial cells), kaolinite
clay and montmorillonite clay within 2, 7, and 30 days, respectively. (2)
No significant decrease in mirex concentration occurred in a
sediment-water system exposed to sunlight for 130 days, but some evidence
of disappearance was noted in purely aqueous solutions. (3) Results from
disc assay tests of bacterial growth inhibition were inconsistent from
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batch to batch of technical grade mirex, with some batches producing
little or no growth inhibition of the bacterial isolates while others
showed marked inhibition. Gas chromatographic studies demonstrated the
presence of varying amounts of unidentified impurities in different
batches of mirex which may account for such discrepant findings. (4) In
culture studies, mirex at concentrations up to 100 ppm did not inhibit
hydrolysis of gelatin, starch, lipid, casein and chitin, glucose
fermentation, H_S production, nitrate reduction, ammonification and
methane utilization. The same concentrations also did not inhibit methane
utilization and nitrification by estuarine sediments. Ten ppm of mirex
did not inhibit the metabolic activity of estuarine pond water organisms
but did inhibit primary productivity. (5) Concentrations of 1000 ppm
mirex did not affect the growth curves of bacterial cultures in broth.
(6) Microcosm studies confirmed the lack of inhibition by mirex.
Concentrations of 1000 ppm did not significantly alter the mixed
microbial populations or the microbial activities of estuarine sediments.
(7) Degradation products of mirex, especially Kepone and reduced Kepone,
were shown to be far more toxic than the parent compounds. (8)
Ultraviolet irradiation of moist mirex resulted in a bacteriologically
toxic material.
The only appreciable microbiological activity affected by mirex at
concentrations below 100 ppm in laboratory experiments was the inhibition
of primary productivity. In the estuarine environment mirex would not be
expected to have any significant effect on primary productivity because
the majority of phytoplankton are in the aqueous phase, whereas mirex
tends to become associated with the sediments. Of critical importance was
the finding that purified mirex was not toxic to microorganisms while
some batches of technical mirex and UV-irradiated mirex were toxic.
Several degradation products of mirex were tested against a number
of bacterial cultures using a disc assay technique. Neither the
monohydrogen derivative or the dihydrogen derivatives with substitutions
at the 2 and/or 2, 8 positions inhibited any of the 10 cultures tested,
whereas degradation products with substitution at the 5 and/or 10
positions were highly toxic. It was not known if any of these compounds
were present in the mirex employed in the investigation.
Brown, et al., concluded that other studies on the toxicity of mirex
should be re-evaluated. This is especially true because one of the
breakdown compounds studied in this investigation has the same retention
times as the mirex itself and because the concentrations of degradation
products that would cause observable toxicity would not be detected by
normal gas chromatographic procedures. All of these compounds are more
polar than mirex and should therefore have higher water solubility than
mirex. These facts may be important for toxicity studies of mirex in
water.
50
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3.3 SOIL MICROORGANISMS
3.3.1 Mirex
Very little information on the behavior of mirex in soils is
available. One study conducted by Jones and Hodges (1974) examined the
persistence of mirex in soils and the effects of mirex on soil
microorganisms. Their study showed that up to 1 gram of mirex per 50 g of
soil (20,000 ppm) had no demonstrable effects on total populations of
soil fungi or bacteria. However, concentrations of 0.5 and 1.0 g
significantly reduced populations of actinomycetes in one out of three
soils. A variety of soil fungi and a few bacteria colonized mirex bait
but failed to degrade the mirex. No degradation of mirex occurred in nine
aerobic soils or four anaerobic lake sediments after 6 months incubation
or in liquid cultures of bacteria after 1 month. C-labeled mirex in
bait placed outdoors for 6 months remained primarily in the bait
particles; only 6.6 percent was found in the top 15 mm of soil. No mirex
leached through a 100 x 110 x 45 mm soil layer with approximately 3
liters of collected rainfall.
These field studies support the conclusion drawn from laboratory tests
that mirex is not degraded by soil microorganisms. Under field conditions,
mirex probably remains in unconsumed bait on the soil surface until the
bait is completely decomposed. Decomposed bait and mirex are probably
incorporated into the soil slowly. Because of the small amount of mirex
applied to the soil (1.7 g/acre application rate) and the low solubility of
mirex it is doubtful that significant amounts leach into groundwater
following mirex application for fire ant control.
3-3.2 Kepone
Virtually the only available reports on the effects of Kepone on
plants, soil microorganisms and transport and distribution of Kepone in
soil are those by Gawaad, et al., (1971, 1973a, 1973b, and 1975).
Information used in this report comes from abstracts and secondary sources
because the original reports by Gawaad, et al., were written in Hungarian.
Unfortunately, translations were not available at the time of writing.
Gawaad, et al., (1971) investigated the quantities of Kepone and other
chlorinated hydrocarbon and organophosphate pesticides leached from several
different types of soil. Simple percolation tests were conducted using
soil-filled metal cylinders which had been perforated at the bottom to
allow collection of the leachate. After treatment with the insecticide, the
water draining from each cylinder was tested for insecticidal concentration
by bioassay, using Daphnia. Kepone applications at a rate of 22.0 kg/ha
(19.6 Ib/acre) to three soil-types in the Nile delta altered fungal,
actinomycete and bacterial population levels for as long as 45 days (when
compared with controls). The significance of this effect from an agronomic
standpoint is unknown especially in view of the unrealistic application
rates used. The magnitude and duration of the effect on population levels
differed with soil type. The microbial populations appeard to return to
51
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normal levels after 15 days despite pronounced fluctuations. Carbon dioxide
production, an indicator of the activity of microorganisms, followed nearly
the same pattern. The authors attribute the strong increase in both the
count and the activity of the soil fungi after the first 7 days to the
intense breakdown and detoxification of the pesticides by the
microorganisms (Gawaad, et al., 1973a). The U.S. Environmental Protection
Agency (1975) criticized these conclusions, and suggested a number of more
plausible explanations which could account for such findings. Suggested
alternative explanations were:
(1) The return to a normal population was a result
of proliferation of organisms tolerant to the
pesticide.
(2) The biological effects of Kepone did not persist
in the soil due to some physical or chemical reason
such as leaching, chemical hydrolysis or volatilization.
In another similar report, Gawaad, et al., (1973b) studied nitrogen
transformations in soils treated with Kepone. During the first 2 weeks
following soil treatment, ammonification of peptone and nitrification of
ammonium sulfate decreased. Although nitrites accumulated in the treated
soils, the nitrate level decreased during the first 15 days, indicating
that organisms of the genus Nitrobacter had been suppressed whereas
organisms of the genus Nitrosomonas had been suppressed to a lesser
degree or not at all.
3.4 SLUDGE MICROORGANISMS
3.4.1 Mirex
Recently, studies by Andrade, et al., (1975) have indicated that
mirex is metabolized very slowly by sewage sludge organisms under
anaerobic conditions. The single metabolite generated has been
tentatively identified as the 10-monohydro product (see Section 2.3-1»
Structure II). After 75 days incubation, autoradiograms of the thin-layer
plates showed two distinct spots for the anaerobic samples, but only one
spot for the aerobic samples and the controls. The ratio of the counts of
the mirex zone was calculated for each sample as quantitative evidence of
the presence of a small amount of a metabolic product. This data is shown
in Table 3•1 -
The data indicate that under the experimental conditions used sewage
sludge microbes degrade mirex under anaerobic conditions. Evidence
provided by the controls as well as the fact that the incubation was done
in the dark eliminated the possibility that the non-mirex spot seen could
have been caused by chemical degradation or photolysis. The data from the
mirex stock solution and controls eliminate the possibility that the
metabolite resulted from autoradiolysis.
52
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TABLE 3.1. RATIO OF RADIOACTIVITY IN MIREX AND METABOLITE ZONES ON THIN
LAYER SILICA GEL PLATESa»b
Ratio
Sample Mirex/Metabolite
Anerobic sludge 88
Anaerobic control 761
Aerobic sludge 636
Aerobic control 470
Mirex stock solution 440
a
Source: Andrade and Wheeler (1974). Reprinted, with permission from Bull.
Environmental Contamination and Toxicology, (c) Springer-Verlag New York
Inc. (1974).
°These experiments were replicated three times using different samples of
sludge. The data presented here are from one experiment and are representa-
tive of the three replications.
53
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3-4.2 Kepone
Few studies have been published concerning the topic of Kepone
metabolism in sewage and sludge. Presumably, Kepone is highly toxic to
sewage digesting microorganisms. Kepone was reported to have killed
massive amounts of beneficial bacteria in the vital digester system at
the sewage treatment facility in Hopewell, Virginia, after Kepone wastes
were dumped into the city's sewage system by Life Sciences Products
Company (Bray, 1975). The exact nature of the discharge and the amount of
Kepone discharged in connection with this incident have not been reported.
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3.5 REFERENCES
Andrade, P., Jr., and W. B. Wheeler. 1974. Biodegradation of Mirex by
Sewage Sludge Organisms. Bull, of Environmental Contain, and
Toxicol. 11(5): 415-116.
Andrade, P., Jr., W. B. Wheeler, and D.A. Carlson. 1975. Identification
of a Mirex Metabolite. Bull, of Environmental Contain, and Toxicol.
14(4): 473-479.
Bevenue, A., J. N. Dgata, L.S. Tengan, and J. W. Hylin. 1975. Mirex
Residues in Wildlife and Soils, Hawaiian Pineapple-Growing
Areas - 1972-74. Pesticides Monitoring J. 9(3): 141-149.
Bray, T. J. 1975. Health Hazard. Chemical Firm's Story Underscores
Problems of Cleaning up Plants. Wall Street Journal, December 2,
1975.
Brown, L. R., E. G. Alley, and D. W. Cook. 1975. The Effect of Mirex
and Carbofuran on Estuarine Microorganisms. EPA-660/3-75-024. U.S.
Environmental Protection Agency, Office of Research and
Development, National Environmental Research Center, Corvallis,
Oregon, 47 pp.
Gawaad, A.A.A.-W., M. A. Hammad and F. H. El-Gayar. 1971. Effect of the
Canal Irrigation System Used in the Persistence of Soil
Insecticides. International Pest Control 13(4): 8-10, 28. Health
Aspects of Pesticides Abstracts 5(4): 72-0686-90 .
Gawaad, A.A.A., M. H. Hamamad, and F. H. El-Gayar. 1972a. Soil
Insecticides. X. Effect of Soil Insecticides on Soil
Microorganisms. Zentralblatt Fuer Bakteriologie, Parasitenkunde
und Infektionskrankheiten und Hygiene, Abt. 2. 127(3): 290-295.
Chemical Abstracts 77: 83 (1972).
Gawaad, A.A.A., M. Hammad, and F. H. El-Gayar. 1972b. Soil
Insecticides. XI. Effect of Soil Insecticides on the Nitrogen
Transformation in Treated Soils. Zentralblatt Fuer Bakteriologie,
Parasitenkunde und Infektions krankheiten und Hygiene, Abt. 2. 127
(3):296-300 Chemical Abstracts 77: 83 (1972) .
Gawaad, A.A.A., F. H. El-Gayar and A. A. Khadr. 1975. Effect of Soil
Insecticides on Plants: III. Effect of Certain Soil Insecticides
on the Germination of Cotton Seeds, Growth, Dry Weight, Cotton
55
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Yield and the Quality of Yield. Acta Agronomica Academiae
Scientarum Hungaricae 24 (1/2): 204-212. Biological Abstracts
61(2): 603 (1976) .
Johnson, J. M., A. M. Dollar, and D. C.Cox. 1976. Mirex Monitoring in
Hawaii - A Cooperative Venture. J. of Environ. Health 38(4):
254-259.
Johnson, J. M., A. M. Dollar, and D. C. Cox. 1976. Mirex Monitoring in
Hawaii...Monitoring Requirements. J. of Environ. Health 38(5):
343-344.
Spenoe, J. H., and G. P. Markin. 1974. Mirex Residues in the Physical
Environment Following a Single Bait Application. 1971-72.
Pesticides Monitoring J. 8(2): 135-139.
U.S. Enviromental Protection Agency, 1975. Kepone. Unpublished Report.
Office of Pesticide Programs, Criteria and Evaluation Division,
U.S. Environmental Protection Agency. 24' pp.
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4.0 EFFECTS ON PLANTS
4.1 SUMMARY
Little work has been done on the effects of mirex and Kepone on
field and pasture crops. Johnson grass and annual rye grass showed
initial significant reduction in growth rate at 0.15 ppm mirex; tall
fescue and alfalfa at 0.3 ppm and alsike clover at 0.70 ppm. One study
indicated that uptake and accumulation of mirex was directly related to
the mirex concentration of the rooting medium. Soybean, garden bean,
sorghum and wheat seedlings showed a similar uptake preference. Plant
root preparations known to metabolize other chlorinated hydrocarbons
failed to yield any metabolite when incubated with mirex. Information on
Kepone metabolism by plants was not available.
4.2 FIELD AND PASTURE CROPS
Examination of all types of biological samples for mirex residues
has generally revealed that the smallest amounts appear to be found in
plants (Markin, et al., 1972). Earlier work by Allied Chemical
Corporation indicated that no mirex residues could be found in a large
selection of field and vegetable crops (Mirex Advisory Committee, 1972).
There is some evidence that extremely low levels of mirex may be
translocated from the soil into growing plants such as bahiagrass roots
and foliage. Mehendale, et al., (1972) also indicated the possibility of
uptake by plants of mirex dissolved in water. Certain aquatic algae were
found to contain relatively high concentrations of mirex (Markin, et al.,
1972). Data on aquatic plants are included in a subsequent section on
aquatic biota.
Little work has been done on the effects of mirex and Kepone on
plants; the areas of seed germination, seedling emergence and survival
and early growth of seedlings have been especially neglected. A study
reported by Rajanna and de La Cruz (1975) investigated the phytotoxic
effects of mirex on several commonly grown field and pasture crops:
crimson clover, Johnson grass, annual rye grass, tall fescue, alsike
clover, and alfalfa. Mirex concentrations employed in the experiment
ranged from 0.3 to 3.5 ppm. Germination experiments utilized germination
blotters presoaked in the prepared mirex solutions. Percent germination
based on number of seeds planted was calculated daily for 21 days.
Emergence and seedling growth were calculated for four replicates of 100
seeds each.
The results of the experiments indicated a significant reduction in
both germination and emergence as the concentration of mirex increased.
Visual examination of the seedlings revealed poor development, suggesting
57
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that uptake of mlrex by the young seedlings caused the damage. Dry weight
of seedlings decreased at higher mirex concentrations. Crimson clover,
Johnson grass and annual rye grass showed initial significant reduction
in growth rate at 0.15 ppm mirex; tall fescue and alfalfa at 0.30 ppm
concentration, and alsike clover at 0.70 ppm. The exact mode of toxicity
of mirex on germination and development of seedlings is not well
understood; however, these studies did not show that uptake and
accumulation of mirex was directly related to the mirex concentration of
the rooting medium. The authors suggest that the phytotoxic effects
observed could be due to a rapid diffusion of water containing mirex
during the germination process.
In a related study, de La Cruz and Rajanna (1975) found that
soybean, garden bean, sorghum and wheat seedlings take up and accumulate
varying amounts of mirex residue when grown in substrates containing from
0.3 to 3.5 ppm mirex. Varying amounts of mirex residues were taken up by
the different parts of the plants grown either in soil or sand, as shown
in Table 4.1. In general, the roots have the highest quantity of mirex
residue. Regardless of difference in species, all plants grown in loamy
sand generally accumulated higher amounts of mirex than those grown in
field soil. Although the concentrations of mirex used in the experiment
are higher than those found in nature, mirex uptake and accumulation by
crop seedlings was demonstrated. At present, there is little available
information on the biochemical fate of mirex once it enters the plant
body or the persistence of mirex in plant tissues beyond the 4-week
duration of this study.
Little information is available concerning the effects of Kepone on
plants, However, Kepone was included in a study on the effects of soil
insecticides on germination of cotton seeds, growth, dry weight and
qualtiy and quantity of cotton yield. Ironically, test results indicated
that yield quality was favorably affected due to a higher lint
percentage. Insecticide residues in the seed were less than 1 ppm under
several different rates of application (Gawaad, et al., 1975).
4.3 METABOLISM
Plant root preparations known to metabolize other chlorinated
hydrocarbons were incubated with mirex but failed to yield any metabolite
(Mehendale, et al., 1972). In the plant study, 2-week-old pea and bean
plants were grown for 48 hours in water containing 1 to 19 ppm of
C-mirex (introduced into 1 percent methylcellosolve solution). Various
parts of the plants were then analyzed for radiocarbon. Mirex was
absorbed by both bean and pea roots in proportion to the concentration of
C-mirex in water as shown in Table 4.2. Translocation to the aerial
parts of 7 to 8 percent of the mirex in the roots occurred, indicating
the possibility that plants do take up mirex in spite of its low water
solubility. The authors failed to comment on the nature of the material
in the roots or shoots. Incubations with preparation from these species
for up to 24 hours gave no evidence of metabolite formation from mirex.
-------
Information on Kepone metabolism by plants was not available.
However, the insecticide Kelevan, which degrades to Kepone, has been
investigated. Sandrock, et al., (19J4) examined the metabolites and
balance in potatoes and soils of C-Kelevan. Eleven weeks after
application of C-labeled Kelevan (ethyl Kepone-5-levulinate) to soils
the main degradation product was Kelevanic acid and by-products were
Kepone and Keponeacetic acid. In another experiment, 5.4 mg C-labeled
Kelevan was sprayed on potato leaves. After harvesting, the C compounds
were found in total potato plants, soil, and drainage water in the
following amounts:
In potato plants:
0.03 mg Kelevan
0.03 mg Kepone
0.24 mg Kelevanic acid
0.04 mg Keponeacetic acid
0.02 mg Unknown extractable compounds
0.01 mg Unknown extractable compounds
14,
Total in plant = 0.37 mg C compounds.
In soil:
Total in soil =
0.08 mg Kelevan
0.06 mg Kepone
0.96 mg Kelevanic acid
0.18 mg Keponeacetic acid
0.06 mg Unknown extractable compounds
0.08 mg Unknown extractable compounds
1.42 mg C compounds.
Total in drainage water, 0.05 mg
14,
14
C compounds.
The C balance in this study was 6.9 percent in potato plants, 26.3
percent in soil, 0.9 percent in drainage water, and 65.9 percent loss to
the air.
59
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TABLE 4.1 CONCENTRATIONS OF MIREX RESIDUES IN DIFFERENT PARTS OF
4-WEEK-OLD CROP SEEDLINGS GROWN IN LOAMY SAND AND EXPERIMENTAL
FIELD SOIL3
Plant parts
Concentration, ppm,
of mirex in the ,
experimental loamy sand
3.4 0.8 0.31
Concentration, ppm,
of mirex in the ,
experimental field soil
3.5 0.8 0.3
Garden beans
Growing tip
Leaves
Upper half stem
Lower half stem
Root
Soybean
Growing tip
Leaves
Upper half stem
Lower half stem
Root
Sorghum
Leaves
Stem
Root
Wheat
Leaves
Stem
Root
0.27
0.40
0.31
0.79
1.68
0.31
0.36
0.73
0.92
1.47
0.40
1.60
1.71
0.21
0.95
1.33
0.09
0.19
0.28
0.38
0.69
0.08
0.18
0.29
0.31
0.49
0.33
0.46
0.67
0.19
0.32
0.55
0.04
0.01
0.17
0.20
0.23
0.05
0.03
0.13
0.27
0.32
0.18
0.21
0.28
0.04
0.21
0.36
0.12
0.20
0.31
0.63
1.18
0.09
0.21
0.35
0.76
1.25
0.22
0.51
0.81
0.17
0.56
1.17
0.06
0.11
0.22
0.25
0.49
0.06
0.12
0.18
0.27
0.49
0.20
0.31
0.44
0.18
0.20
0.27
0.02
0.01
0.10
0.02
0.21
0.01
0.10
0.11
0.12
0.17
0.11
0.17
0.20
0.09
0.20
0.23
aSource: delaCru.z and Rajanna (1975). Reprinted, with permission, from Bull.
Environmental Contamination and Toxicology, (c) Springer-Verlag New York,
Inc (1975).
^Analysis by GC.
60
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TABLE 4.2 UPTAKE OF MIREX BY PEA AND BEAN PLANTS3>b
Mirex-14C
in water
ppm
1
5
10
Peas,
Roots
6.487
40.696
71.285
ppm
Shoots
0.586-
1.521
8.408
Beans ,
Roots
8.478
45.364
101.604
ppm
Shoots
0.496
3.867
6.834
aSource: Mehendale, et al. (1972). Reprinted, with
permission from Bull. Environmental Contamination and
Toxicology, (c) Springer-Verlag New York, Inc. (1972).
x-^C (5 x 106 dpm) along with desired amount of
unlabeled mirex was introduced in water as methyl-
cellosolve (1 percent) solution.
61
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4.4 REFERENCES
De La Cruz, A. A., and B. Rajanna. 1975. Mirex Incorporation in the
Environment: Uptake and Distribution in Crop Seedlings. Bull, of
Environmental Contam. and Toxicol. 14(1): 38-42.
Gawaad, A.A.A., F. H. El-Gayar and A. A. Khadr. 1975. Effect of Soil
Insecticides on Plants: III. Effect of Certain Soil Insecticides
on the Germination of Cotton Seeds, Growth, Dry Weight, Cotton
Yield and the Quality of Yield. Acta Agronomica Academiae
Scientarum Hungaricaze 24 (1/2): 204-212. Biological Abstracts
61(2): 603 (1976) .
Markin, G. P., J. H. Ford, J. C. Hawthorne, J. H. Spence, J. Davis, H.
L. Collins, and C. D. Loftis. 1972. The Insecticide Mirex and
Techniques for Its Monitoring. U.S. Department of Agriculture,
Animal and Plant Health Inspection Service, Hyattsville, Maryland.
APHIS 81-3. 19 PP.
Mehendale, H. M., L. Fishbein, M. Fields, and H. B. Matthews. 1972.
Fate of Mirex- C in the Rats and Plants. Bull, of Environmental
Contam. and Toxicol. 8(4): 200-207-
Mirex Advisory Committee. 1972. Report of the Mirex Advisory Committee
to William D. Ruckelshaus, Administrator, Environmental Protection
Agency, February 4, 1972. Unpublished Report. 72 pp.
Sandrock, K., D. Bieniek, W. Klein and F. Korte. 1974. Ecological
Chemistry LXXXVI. Isolation and Structural Elucidation of Kelevan
C Metabolites and Balance in Potatoes and Soil. Chemosphere
3(5): 199-204.
62
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5.0 EFFECTS ON BIOTA
5.1 SUMMARY
The ecological significance of mirex in the aquatic environment does
not necessarily depend upon the amount of the residue that enters the
water. Instead, the ecological and biological significance of mirex
depends upon its mode of incorporation into aquatic organisms and its
effects on organisms chronically exposed to low concentrations of this
pesticide. The solubility of mirex in fresh water does not exceed 1 ppb
(0.001 ppm), and may be 0.2 ppb or less in seawater (Section 2.3.1-1).
Rather than remaining suspended in the water column for any extended
length of time, mirex is rapidly adsorbed onto various organic particles
and removed to the sediments where it may have an appreciable lifetime.
Mirex, in environmental concentrations, does not appear to be
directly toxic to marine algae or freshwater phytoplankton in terms of
population growth, oxygen evolution, or primary productivity. Several
species of marine algae tend to accumulate (but not metabolize) mirex
from water. Therefore, these organisms may very well act as physical
agents in transporting mirex into estuarine or marine ecosystems and to
consumers in the food chain.
Bioaccumulation and biomagnification potential of mirex vary among
invertebrate species and among the life stages of certain of those
species. Bioaccumulation is generally a function of exposure period and
mirex concentration. The mirex levels accumulated by invertebrate species
suggest the potential hazard involved if these organisms transport the
pesticide to secondary and tertiary consumers in aquatic food chains or
to human consumers of these food commodities.
Mirex is accumulated by fish from water and from food chain
organisms. It accumulates mainly in the fatty tissue and visceral organs
of most fish species. However, some species such as bass, bream, catfish,
and mullet have been found to contain at least 1 ppm of mirex in their
edible portions. Mirex has, for the most part, relatively insignificant
effects on fish growth and oxygen consumption. Some pathological
developments such as granulomatous kidney lesions and edematous gill
changes were noted among mirex-fed goldfish. Mortalities among fish
species were not always found to be mi rex-related.
Laboratory and field studies show that the food chain is the mode of
transport of mirex in natural populations. Mirex is concentrated by
algae, invertebrates, and fish. The total environmental significance of
mirex residues in nontarget species, however, is mostly unknown. Levels
well over 1 ppm are found in a number of animals at the top of the food
63
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chains; some of these fish and invertebrate species are commonly used for
human consumption. Therefore, man does have direct access to a
potentially hazardous chemical through his food chain.
Effects of mirex on invertebrate species, especially estuarine
crustacens, vary from irritability and loss of equilibrium to death.
Juvenile brown and pink shrimp and juvenile blue crabs were found to be
the estuarine species most susceptible to mirex. Of particular interest
is the delayed mortality exhibited by invertebrate species (e.g.,
crayfish, juvenile pink shrimp, and juvenile blue crabs) exposed directly
or indirectly to mirex
Kepone, like mirex, has a low solubility in freshwater and seawater.
The ecological and biological significance of Kepone in aquatic systems
depend upon its bioaccumulation by aquatic organisms and its transfer
potential among organisms comprising aquatic and human food chains. Algal
species accumulate Kepone from water and may pass the pesticide along the
food chain to man. The few data available on the effects of Kepone show
that Kepone reduces algal growth. Exposures to Kepone concentrations
ranging from 0.35 to 1.0 ppm are deemed to be sufficient to disturb or
destroy the lowest level of the aquatic food chain, thereby directly
affecting productivity at other levels of the food chain.
Although much of the data on Kepone acumulation by invertebrates are
based on laboratory exposures to unreallstically high concentrations,
these experiments show that invertebrates are capable of bioaccumulating
Kepone to dangerously high levels. Kepone bioconcentration factors vary
among invertebrate species because of the difference between depuration
rates. Kepone is acutely and chronically toxic to estuarine inverterate
species. Besides mortality, effects of Kepone include loss of
equilibrium, reduction of reproductive success, and decrease in shell
growth.
Kepone is bioaccumulated and persistent in fish species such as
sheepshead minnows and spot. Even juvenile progeny of adult fish (e.g.,
sheepshead minnows) exposed to Kepone, hatched and grown in Kepone-free
water, contained Kepone. One reason is that fish have slow depuration
rates as compared with some invertebrates such as oysters. Female fish
sometimes have Kepone residues higher than those of male. One of the
largest Kepone reserves was in the edible portion of the contaminated
fish. Symptoms of Kepone poisoning in fish have been correlated with
concentration and duration of exposure. Among several fish species
exposed to Kepone under varying laboratory conditions, symptoms ranged
from diminished activity and emaciation to abnormal development and
mortality. Yet another observed effect of Kepone is ATPase inhibition
which reduces the energy available to the organism.
The accumuation, transfer, and loss of Kepone has been verified in
estuarine food chains via laboratory bioassays. Transfer and retention of
Kepone from algae by invertebrates with high depuration rates (e.g.,
oysters) are inefficient, while transfers between invertebrates and
-------
between invertebrates and fish are efficient. Because of the efficient
transfer of Kepone between fish food organisms and fish, there is a great
potential for Kepone transfer to humans via consumption of fish.
Mirex does not appear to present a serious acute toxicity problem to
nontarget terrestrial invertebrates following the proper usage of mirex
bait. Mirex residue levels are low, typically 0.1 ppm in most
phytophagous animals collected from mirex treated areas. However, general
scavengers such as crickets and cockroaches, which may consume the bait
pellets directly, have been shown to acumulate mirex residues in the 10
to 30 ppm range. Information regarding Kepone toxicity in these species
comes only from experimental situations, but orchard monitoring studies
suggest that Kepone, too, is not acutely toxic to predaceous insects at
up to five times the typical dosage used in agricultural applications.
Information on amphibian and reptile responses to both pesticides is
inadequate, however, environmental surveys have consistently found mirex
residues to be lower in these species than in birds and mammals.
In comparison with mammals and fish, birds are less sensitive to
mirex in either acute or chronic exposures. Chickens, for example,
require a daily consumption of 300 to 600 ppm mirex in food to produce
reproductive effects; subacute toxicity tests on a variety of bird
species produced mortality at feeding levels of 200 to 500 ppm after 30
to 111 days. Mirex is remarkably accumulative in tissues following
long-term dietary exposures. The highest residues are found in skin and
fat. These tissues can accumulate over 200 times the concentration of
mirex in the diet. One of the most interesting characteristics in birds
is the differential residue patterns seen between males and females.
Because mirex accumulates in egg yolks, egg laying represents an
important excretion route. Long-term metabolic studies of quail, for
example, have shown that hens establish an equilibrium between mirex
intake and elimination through the eggs, while in male residues continue
to accumulate and show little tendency to reach a plateau. Reproductive
effects such as decreased egg production, decreased survival of chicks,
reduced hatchability and eggshell abnormalities have been observed in
several bird species. The threshold dosage, required to elicit
reproductive effects (assuming generalization across avian species)
probably lies in the range of 40 to 100 ppm mirex in the diet.
Wildlife sampling surveys in or near treated areas have shown that
birds as a group contain relatively high levels of mirex. These high
levels presumably relate to the fact that birds consume a great deal more
food on a per weight basis than do insects, reptiles and mammals. The
most important determinants of mirex levels in these birds are dietary
patterns (i.e., carnivorous versus herbivorous) and whether or not the
home range extends beyond the treated areas. Highly lipid-soluble
chemicals such as mirex are bioconcentrated by fish which, in turn,
provide potent sources of mirex to predatory birds as seen in herring
gulls in the Great Lakes region (See Section 5.3-3.5).
65
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Like mirex, Kepone is not very toxic to birds as an acute poison. In
subacute dosages, Kepone is considerably more toxic than mirex. Tremors,
pathologic changes in the liver and reproductive difficulties similar to
an "estrogenic effect" are seen in both sexes at dietary levels of 200
ppm of Kepone. Furthermore, the finding of reduced survival in stress
situations (due to mobilization of Kepone-laden fat stores) suggest that
a large body burden of Kepone, while not producing symptoms of toxicity
in normal situations, may dramatically reduct the ability of the birds to
successfully cope with environmental stresses.
Mirex administered as an acute oral dose is not very toxic to those
mammalian species that have been tested. Acute LD _'s for rats lies in
the range of 365 to 7^0 mg/kg; many other organochlorine and
organophosphorus pesticides have much lower LD_'s. The most commonly
observed subacute toxic effects of mirex in mammals are weight loss,
increased liver weight and reproductive difficulties. Pathologic liver
changes have been noted in rats fed as little as 5 ppm of mirex for 5-1/2
months.
Mirex has the highest chronicity factor observed in any pesticide
examined to date. This fact, coupled with slow excretion and lack of
metabolism indicate that mirex is highly cumulative in effect. Metabolic
studies have shown a pattern of steady accumulation in the organs and a
very slow rate of dissipation following withdrawal of mirex treatment in
both mammal species tested (rats and rhesus monkeys). No significant
metabolism of mirex within the body has been documented.
Other chronic effects of mirex are induction of hepatic microsomal
enzymes, inhibition of several liver enzymes (LDH, MDH, SDHH, GOT, and
GPT) and proliferation of smooth endoplasmic reticulum.
Mirex and Kepone produce similar adverse reproductive effects in
numerous species tested. These include reductions in fertility and litter
size, visceral anomalies, elevated pesticide levels in offspring
(resulting from placental and lactogenic transfer) and decreases in birth
weight and survival of young.
Mirex has been shown to be tumorigenic, and possibly carcinogenic in
mice, producing chiefly liver tumors, however, reticular cell sarcomas
and pulmonary adenomas were also seen. In oral administration tests,
mirex possesses nearly the same carcinogenic potency as seven known
carcinogens when tested under the same protocol (relative risk for mirex
was 0.9M5).
Kepone, in both oral and dermal administrations is more acutely
toxic than mirex in mamma Han species. The most characteristic symptom of
acute or subacute Kepone intoxication in mammals is severe and persistent
tremor. Enlargement and congestion of the liver, weight depression,
increased oxygen consumption and urinary excretion of protein and sugar
were reported in chronic toxicity studies on rodents and dogs.
66
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Like mirex, Kepone accumulates in mammalian tissues, and excretion
following termination of dietary exposure is slow. No metabolites of
Kepone have been detected in various organs of Kepone-fed mice; such a
finding is suggestive of great biological stability of Kepone once it
enters the body. Reproductive effects, placental and lactogenic transfer,
and teratogenic effects are similar to those described for mirex. Kepone
is a documented carcinogen in rats and mice. Following long-term
exposures (80 weeks) significant increases in hepatocellular carcinomas
were observed in tests conducted by the National Cancer Institute. Tests
conducted by Allied Chemical Corporation also indicated that Kepone is
oncogenic, however, the findings of that study were somewhat more
equivocal.
5.2 AQUATIC BIOTA
5.2.1 Mirex
The ecological significance of mirex incorporation into the aquatic
environment does not necessarily depend upon the amount of the residue
that enters the water. What is ecologically and biologically significant
is the manner in which mirex is taken up by aquatic organisms and the
effects of this pesticide on biota chronically exposed to low
concentrations of the chemical (de La Cruz and Naqvi, 1973).
Chlorinated hydrocarbons, including mirex and Kepone, have low
solubilities in water; the solubility of mirex in fresh water does not
exceed 1 ppb, and may be 0.2 ppb or less in seawater (Section 2.3-1.1).
Rather than remaining suspended in water, mirex is rapidly adsorbed on
various organic and inorganic particles which settle to become part of
the sediments. Brown, et al., (1975) showed that at least 95 percent of
the mirex in aqueous solutions is removed by adsorption on organic
matter, kaolin!te clay and montmorillonite clay within 2, 7, and 30 days,
respectively. Therefore, in nature, mirex will not remain long in the
water column but instead will be removed to the sediments where it may
have an appreciable lifetime. At environmentally realistic concentrations
mirex does not appear to be directly toxic to marine algae and freshwater
phy to plankton in terms of population growth, oxygen evolution, or primary
productivity (Brown, et al., 1975; Hollister, et al., 1975). Several
types of algae have shown a propensity to accumulate mirex from water,
indicating that algae may act as passive transporters of mirex to
consumers in the food chain. In addition, adsorption on various organic
particles in the sediments results in high toxicant input to detritus
feeders (Leffler, 1975).
5.2.1.1 Algae and Phytoplankton—
Little information is available on mirex (its uptake, accumulation,
or effects) and algae and/or phytoplankton. Butler (1963) found that the
exposure of phytoplankton to 1 ppm mirex for 4 hours reduced productivity
by 28 to 46 percent. After being exposed to 1 ppm mirex for 168 hours,
pure cultures of the green alga Chlamydomonas sp. exhibited a 55 percent
67
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reduction in photosynthesis (de La Cruz and Naqvi, 1973). In fact, net
photosynthesis was reduced from 122 mg C/m /hr in control cultures to 55
mg C/m^/hr in mirex-treated cultures. The respiration rate was, likewise,
reduced from 362 to 259 mg C/m /hr. These data concur with reported
findings on the effects of various pesticides on photosynthesis.
Hollister et al., (1975) exposed marine green algae (Chlorococcum
sp., Dunaliella tertiolecta and Chlamydomonas sp.), diatoms
(Thalassiosira pseudonana), and red algae "TP orphirdiurn cruentum) to 0.2
ppb mirex to determine the effects of mirex on population growth and
oxygen evolution under various conditions of salinity and nutrient
concentration. (Due to its low solubility in seawater 0.2 ppb mirex has
been the highest test concentration obtainable). Mirex had no significant
effect on either population growth (Figure 5.1) or oxygen evolution. The
same organisms were exposed to 10, 25, or 50 ppt mirex to determine if
mirex can be accumulated by these algae. Eighty-eight percent of mirex
was removed from the medium by Chlorococcum whereas Dunaliella and
Thalassiosira removed about 79 percent and Chlamydomonas * uptake was 55
percent. Chlorococcum concentrated mirex 7300 X, Dunaliella 4100 X,
Chlamydomonas 3200 X, and Thalassiosira 5000 X the concentration in the
culture medium (Figure 5.2). The ability to take up and concentrate mirex
indicates that these marine algae have great potential as passive
transporters of this toxicant to consumer organism in the food chain.
Sikka, et al. , (1976) studied the effects of mirex on the
photosynthesis of green (Ulva lactuca and Enteromorpha linza) and red
(Rhodymenia pseudopalmata) marine algae at a concentration of 10.2 ppb.
This is probably an environmentally realistic mirex concentration because
it did not exceed its solubility in the growth medium (synthetic
seawater). The effect of mirex on the chemical composition of the
seaweeds and of the uptake and metabolism of mirex by those algae was
also investigated. Mirex did not adversely affect photosynthesis and the
chemical composition ofV Ulva, Enteromorpha, and Rhodymenia. The three
species readily removed C-mirex from the medium (mirex concentration in
the medium was 15 ppb) and continued to remove mirex up to 144 hours
after treatment when the experiment was terminated. Mirex was also
accumulated by all three algal species, the bioaccumulation factor
ranging from about 350 to 1100. None of the test organisms was able to
metabolize mirex. Although mirex did not affect the seaweeds used in this
study, the ability of the algae to accumulate mirex suggests that these
organisms may act as physical agents in transporting this pesticide in
estuarine ecosystems.
5.2.1.2 Aquatic Invertebrates—
5.2.1.2,1 Uptake and accumulation—Exposure of selected aquatic
invertebrates to mirex revealed species variability in uptake which was
generally a function of exposure period and concentration (Ludke, et al.,
1971; de La Cruz and Naqvi, 1973). Freshwater crustaceans Orconectes
mississipiensis, crayfish; Palaemonetes kadiakensis, shrimp; Hyallela
azteca, amphipod, leeches (Placobdella rugosa, Glossiphona sp.,
68
-------
Chlamydomortal (p.
HltxuMa ip.
.200
.100
I
K
tt .300r
trvuntvm
Chlorococcum sp.
& »«rttel»
-------
300
I
M
I
z
o
u
z
20O
100
10 25 50
CONCINTXATION IN IMDIUM (pptr)
FIGURE 5.2.
Uptake of mirex by algal Dooulations after seven days
exposure.
aSource: Hollister, et al (1975). Reprinted, with
permission, from Bull. Environmental Contamination
and Toxicology, (c) Springer-Verlag New York Inc.
(1975).
TO
-------
Eropobdella punctata), and dragonfly naiads, Macromia sp. were exposed
for 24 to 672 houqs to aqueous test solutions formulated to contain 0.001
to 2.0 ppm mirex . There was great species variability in the rate of
uptake of mirex. Tests conducted at the 2-ppm level for 48 hours showed
an uptake of 10.0 ppm in Palaemonetes kadiakensis and 11.0 ppm in
Orconectes mississippiensis which was more than twice the level of mirex
residue detected in the three species of leeches (Erpobdella punctata,
1.9 ppm; Placobdella rgosa, 4.9 ppm; and Glossiphonia sp., 5.1 ppm).
Mirex uptakes in Orconectes, Placobdella, and Macromia showed differences
in residue levels with respect to concentration and duration of exposures
(de La Cruz and Naqvi, 1973).
Collins, et al., (1975) found 0.40 ppm mirex in crayfish (Camarellus
schufeldtii) 5 days after an aerial application of mirex bait (1.4 kg/ha,
1.25 Ib/ac) to a 1.22 hectare (3-acre) fish pond and the surrounding
drainage area. After 16 months, residues as high as 0.02 ppm were still
present. In that same study, dragonfly nymphs (5 or more undetermined
species) contained 0.70 ppm mirex 5 days following the aerial
application. Sixteen months later, a concentration of 0.03 ppm mirex was
found in the nymphs.
Thirty-five freshwater crayfish (Procambarus blandingi), about 1 cm
long, were exposed to 35 granules of mirex bait (0.3 percent active
ingredient). Triplicate samples (6/sample) had body residues of 1.60,
1.41, and 1.34 ppm mirex (Ludke, et al., 1971). Substantial amounts of
mirex obviously leached from the granular bait into the water. The
animals accumulated a residue (average of 1.45 ppm) 16,860-fold greater
than that in the water (an average of 0.86 ppb of mirex had leached into
the water).
Tissue residue analyses of P_^ blandingi which had been directly fed
two granules of mirex bait revealed an increase in residue concentration
with length of exposure (Ludke, et al., 1971). Mirex residues in crayfish
bodies were from 940-fold to 27,200-fold greater than the concentration
in the surrounding water. Mirex concentration in the digestive glands
from four individuals living after eight days of exposure was
126,600-fold greater than that in the water. Body residue levels of mirex
ranged from 3.9 to 6.1 ppm and correlated with the period of highest
increase in mortality (2 and 3 days post-feeding). These data show that
crayfish concentrate mirex rather efficiently from bait granules and
emphasize the potential hazard of biological magnification of this
toxicant.
Mar kin, et al., (1972), in light of the laboratory investigations of
the sensitivity of crayfish to mirex and the amount of mirex used in
crayfish-growing areas of Louisiana, examined levels of mirex in the
edible red crayfish to determine whether continued use of mirex could
threaten this locally important industry. Secondly, they wanted to
determine whether mirex residues in crayfish in treated areas approach
the levels found to affect crayfish under laboratory conditions. Samples
were collected at the peak of the crayfish harvests in May, 1971. All
71
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collections were made from ponds, canals, and bayous which were adjacent
to pastures that had a history of mirex bait application. Seven of 28
samples showed detectable residues of mirex, but these residues could
neither be associated with the frequency of the treatment nor the type of
crayfish habitat. The few residues which were detected ranged from 0.01
to 0.07 ppm, well below the 1- to 8-ppm level reported to kill juvenile
crayfish in the laboratory.
In 1969, a cooperative USDA and USDI experiment was set up at
Charleston,, South Carolina, to study effects of mirex on crab and shrimp
populations (Markin, et al., 1974). Mirex was applied three times to a
2-square mile area of marshland and estuaries. Biweekly samples were
collected within the treated areas during the application period and for
3 years afterwards, and analyzed for mirex residues. Mirex residues over
the period ranged from 1.54 ppm 1 week after the first treatment to less
than 0.001 ppm (negligible) 3 years after the third and final application.
Laboratory experiments were conducted to determine the effects of
mirex and other pesticides on the larval development of blue crabs,
Callinectes sapidus, from the time of hatching until the first crab stage
was reached (Bookhout and Costlow, 1976). Larvae of three mother crabs
were reared in mass cultures consisting of an acetone control and 0.01,
0.1, 1.0, and 10.0 ppb mirex (added as an acetone solution) to obtain
enough wet weight of larvae (0.30 to 0.20 g) for residue analysis.
Residue analyses were made to assess relationship between length of time
in each concentration and residues of mirex and between mirex
concentration and eventual residue concentration.
No detectable mirex ( 5 ppb) was found in freshly hatched larvae in
seawater, nor in 5- and 15-day larvae, megalopa, or in first- and
second-stage crabs which had been reared in the control containing only
acetone. Larvae reared in a range of concentrations of mirex from 0.01 to
10.0 ppb showed increased residues of mirex with increased concentrations
(Table 5.1). According to these residue analyses, the biological
magnification was greatest in larvae reared in 0.01 ppb and decreased
with concentration from 0.1 to 10.0 ppb mirex. These seemingly anomalous
results are probably explained by the fact that crabs, being sensitive to
mirex, are killed at the higher concentrations. Typically, however, only
live organisms are assayed in these experiments.
Fourth and fifth stage crabs (Rhithropanopeus harrisii) contained
0.13 ppm mirex after a 48-day exposure to 0.1 ppb of the pesticide. No
residues were detected in those R. harrisii crabs, reared in a solution
of 0.01 ppb mirex. The presence of 0.015 ppm mirex in crabs (Menippe
mercenaria) reared in 0.01 ppb mirex indicates that during these
developmental stages crabs absorbed mirex during development to the
second crab stage and concentrated it 1500 X. Crabs reared in 0.1 ppb
mirex during development to the second crab stage absorbed and
concentrated it 2400 X (0.24 ppm) (Bookout, et al., 1972).
72
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TABLE 5.1. MIREX RESIDUES IN BLUE CRABS AND THEIR LARVAEa
Sample Identification and Treatment Mirex, ppb
First-day larvae - Seawater <5
5-day larvae - Acetone Control <5
15-day larvae - Acetone Control <5
Megalopa - Acetone Control <5
Crabs, 1st and 2nd - Acetone Control <5
5-day larvae - 0.01 ppb Mirex 11
15-day larvae - 0.01 ppb Mirex 30
Megalopa - 0.01 ppb Mirex 20
Crabs, 1st and 2nd - 0.01 ppb Mirex 9
5-day larvae - 0.10 ppb Mirex 33
15-day larvae - 0.10 ppb Mirex 70
Megalopa - 0.10 ppb Mirex 65
Crabs, 1st and 2nd - 0.10 ppb Mirex 77
5-day larvae - 1.0 ppb Mirex 301
8-day larvae - 1.0 ppb Mirex 406
5-day larvae - 10.0 ppb Mirex 1620
8-day larvae - 10.0 ppb Mirex 1370
Mother Crab Cs II - Seawater 10
Mother Crab Cs III - Seawater <5
Mother Crab Cs V - Seawater <5
aAdapted from Bookhout and Costlow (1976).
73
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Juvenile pink shrimp, Penaeus duorarum, were exposed to 0.1 ppb of
technical-grade mirex in flowing seawater for 3 weeks (Lowe, et al.,
1971). Residue analyses of composite liver samples and remaining tissues
were conducted after the crabs were placed in mi rex-free seawater for 2
weeks. The livers (hepatopancreases) contained 2.4 ppm of mirex; the
remaining tissues, 0.32 ppm. A composite sample of five whole shrimp
contained 0.26 ppm of mirex.
Five juvenile blue crabs (Callineotes sapidus) were fed one fish
(0.4 microgram mirex) a day for 5 days and uncontaminated fish thereafter
(Lowe, et al., 1971). Three of the crabs, moribund or dead 3 weeks after
receiving the fifth contaminated fish, contained 0.13, 0.22, and 0.25 ppm
(0.85, 0.48, and 0.78 micrograms) of mirex. The two remaining crabs alive
for 5 weeks after eating the fifth contaminated fish contained 0.10 and
0.13 ppm (0.37 and 0.57 micrograms) mirex. Another group of five juvenile
blue crabs was fed only one juvenile fish containing 1.0 ppm of mirex per
crab and uncontaminated fish thereafter. Sixty days later, four of the
crabs were still alive and contained 0.045, 0.025, 0.052 and 0.027 ppm
(0.23, 0.14, 0.19, and 0.11 micrograms) of mirex, about one-half the
total amount of mirex ingested with the single contaminated fish (Lowe,
et al., 1971). In another experiment, 25 juvenile crabs were placed in an
aquarium through which flowing seawater passed. Each crab received one
particle of mirex bait. Four weeks after the bait was fed to the crabs,
residue analyses were conducted on individual crabs; the average mirex
content was 0.99 ppm (Lowe, et al., 1971).
Schoor and Newman (1976) exposed adult polychaete worms (Arenicola
cristata) to mirex bait granules equivalent to five times the field rate
application (1.40 kg of 0.3 percent mi rex/hectare) in a modified airlift
column. Egg masses appeared in the treated tank on days 4 and 23- The
exposure was terminated on day 30 and both the treated and control tanks
were observed for another 45 days. Twelve swimming juvenile worms were
analyzed for mirex on day 63. Their whole-body residue was 60 ppb of live
weight. The experiment was terminated on day 75 and the original adult
worms were analyzed. The whole-body mirex residue of the adults was 500
ppb (dry weight). Aside from predation on adult worms, swimming juvenile
lugworms could transmit mirex to predators,which is an example of
biological feedback. (Effects are described in Section 5.2.1.2.2).
5.2.1.2.2 Effects—Two species of freshwater crayfish (Procambarus
blandingi and P. Hayi proved to be extremely sensitive to mirex through
direct and indirect exposures under laboratory conditions (Ludke, et al.,
1971). Of all the size groups tested, third instar crayfish were most
sensitive to the toxicant. Delayed mortalities resulted from both low
concentrations and short duration exposures to aqueous mirex as well as
to oral administration in all size classes of crayfish used. Mortality
among juvenile crayfish (P. blandingi) approached 100 percent in 5 days
upon exposure to 1 ppb mirex for 144 hours (Table 5.2). P. Hayi exhibited
65 and 71 percent mortality, respectively, 4 days following the end of a
48-hour exposure to 0.1 and 0.5 ppb mirex.
74
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TABLE 5.2. PERCENT MORTALITY OF £. BLANDINGI AND P_. HAYI FOLLOWING
INITIAL EXPOSURE TO VARIOUS CONCENTRATIONS OF MIREX*
Hortality, Percent
Concentration ,
ppb
Exposure
Time, hr
Number
Tested
At
End of
Exposure
At Days Following
of Exposure
4 5
End
10
PJ? Blandingib
1
5
5
5
0.1
0.5
144
6
24
58
48
48
30
30
30
40
P.
30
30
0
0
6
5
Hayic
19
12
95
2
13
76
65
71
95
26
50
98
—
aSource: Ludke, et al. (1971). Reprinted, with permission, from Bull.
Environmental Contamination and Toxicology, (c) Verlag-Springer New York,
Inc. (1971).
Average length 1.5 cm.
Average length 0.6 m.
75
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Feeding tests revealed that juvenile and adult crayfish (P.
blandingi) suffered high mortalities after consuming extremely small
amounts (1 or 2 granules) of mirex bait (0.3 percent active ingredient).
The greatest mortality occurred during the second and third day after
feeding. Some adult P. hayi were fed mirex bait-fed mosquitofish for 9
days and subsequently fed untreated mosquitofish for 50 days. Four of the
five crayfish died. The high mortality in those individuals fed
contaminated mosquitofish emphasize the potential for biological
magnification (Ludke, et al., 1971).
Although Ludke, et al., (1971) found P. blandingi and P. hayi to be
extremely sensitive to mirex under laboratory conditions, an earlier
study of adult crayfish had indicated that they were not sensitive to
mirex at the concentrations used in large-scale fire ant control projects
(Muncy and Oliver, 1963). Despite evidence of extreme sensitivity of
crayfish to mirex under laboratory conditions, field studies and
monitoring in the estuarine environment revealed no evidence of massive
die-offs or noticeable population declines. In fact, doubt has been cast
on the present use of mirex being a threat to the crayfish industry
(Markin, et al., 1972).
Exposure to mirex under laboratory conditions affects certain
estuarine crustaceans by causing irritability, loss of equilibrium,
undirected movement, paralysis, and even death. The onset of symptoms
depends on the level of exposure or amount of mirex ingested,
temperature, and, in some cases, the age or size of the animal being
tested. The most susceptible species were found to be juvenile brown and
pink shrimp and juvenile blue crabs (Lowe, et al., 1971; Bookout and
Costlow, 1976; Leffler, 1975).
For blue crabs, Leffler (1975) considers mirex to be more hazardous
than DDT. This is supported by a laboratory study in which the effects of
ingested mirex on the metabolic rate, ionic and osmotic regulation,
ability to autotomize limbs, and carapace thickness of juvenile blue
crabs (Callinectes sapidus) were determined. Food particles, treated with
acetone solutions of mirex, were placed directly against the crab's
mouthparts and were devoured within a couple of minutes.
Ingested mirex was highly toxic to the juvenile crabs. Toxic
responses (convulsions and death) were most pronouunced in media with
very high or very low salinities. Internal mirex concentrations in crabs
exhibiting toxic responses averaged 0.42 0.05 ppm after three to four
weekly feedings of 0.14 microgram mirex each. Pronounced elevations of
metabolic rates were induced by high subacute internal levels (0.19
0.03 ppm) of mirex. Mirex concentrations as low as 0.02 ppm in body
tissues also caused significant metabolic rate elevations.
Mirex had no significant effect on the ionic composition of the hemolymph
or its total osmotic concentration at subacute internal levels of 0.19
76
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ppm mirex. The same mirex concentrations decreased the carapace
thickness/width ratio of molt cycle stage Cj. crabs. Internal mirex
concentrations of 0.02 ppm and above inhibited the autotomy reflex, In
fact, only 29 percent of mirex-treated crabs with a damaged limb
autotomized that limb. The above data verify that 0.14 microgram mirex
ingested by blue crabs from a food source in the environment may result
in the adverse effects outlined above.
Bookhout and Costlow (1976) exposed blue crab larvae to mirex
concentrations of 0.01 to 10.0 ppb to examine developmental effects. The
mirex levels had no appreciable effect on day-to-day survival of two
replicate series of larval crabs for five days after hatching. After a
5-day period of delayed mortality (observed at all experimental
concentrations of mirex) concentrations of 0.01 and 0.1 ppb were shown to
be sublethal while 1 and 10 ppb were acutely toxic.
In one series of tests with blue crab larvae, 0.5 percent of 200
larvae reached the crab stage in 1.0 ppb mirex but no larvae from a
second series survived beyond 20 days. Also, in the two series of crab
larval tests, the duration from hatching to megalopa and to the first
crab stage in 0.01 and 0.1 ppb mirex showed no statistical difference. In
the acutely toxic concentration of 1.0 ppb mirex only 2 percent of one
group of larvae reached the megalopa stage, taking 11 days longer to do
so than those reared in the sublethal concentrations.
These investigators concluded that blue crab larvae are about as
sensitive to mirex as juvenile blue crabs. Again, the sensitivity to
mirex of the blue crab larval and juvenile life stages is extremely
significant because their survival success determines the fate of entire
blue crab populations.
In a study of the effects of mirex on the complete larval
development of two crabs, Rhithropanopeus harrisii and Menippe
mercenaria, Bookhout, et al., (1972) obtained results quite similar to
those of Bookhout and Costlow (1976). The same mirex concentrations were
found to be sublethal and acutely toxic. Delayed mortality was also noted
in the early stages of zoeal development. Larvae of Menippe were much
more sensitive to various concentrations of mirex than were those of
Rhithropanopeus, especially in the megalopal stage. However, survival was
reduced in relation to increased mirex concentrations in both genera. The
duration of development of Rhithropanopeus was extended with increasing
mirex concentrations. In the case of Menippe, the duration of stages
fluctuated but showed very little evidence of becoming longer as mirex
concentrations increased.
Lowe, et al., (1971) cited an earlier study conducted in their
laboratory in which juvenile blue crabs and juvenile pink shrimp (Penaeus
duorarum showed no symptoms of poisoning during a 96-hour exposure to a
suspension of 0.1 ppm technical mirex in flowing seawater. These
organisms, however, did become irritated and paralyzed, and died within
77
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18 days after being placed in mirex-free water. This serves as an
additional illustration of delayed mortality among mirex-exposed
crustaceans.
In the above study, Lowe, et al., found that exposure to one
particle of bait (ca. 4.4 micrograms mirex) per juvenile blue crab caused
significant mortality (53 to 84 percent) by the end of the 4-week
experimental period. Fiddler crabs (Uca pugilator) were also susceptible
to pof.soning by mirex. Exposures to 50 mg of mirex bait (which is
equivalent to a field application of 1.4 kg/ha) caused 73 percent
mortality or paralysis within two weeks.
Juvenile brown shrimp (Penaeus aztecus) and grass shrimp
(Palaemonetes pugio) died after exposure to mirex bait (0.3 percent
active ingredient) at levels as low as one particle of bait per shrimp in
standing seawater. Within 96 hours, the above exposure resulted in 60 and
70 percent mortality, respectively, in brown and grass shrimp (Lowe, et
al., 1971).
Juvenile pink shrimp (Penaeus duorarum) are extremely sensitive to
mirex dissolved in seawater. Twenty-five percent (9 of 36) of the shrimp
became irritated and died during a 7-day exposure to 1.0 ppb of technical
mirex in flowing seawater. The remaining 75 percent died within 4 days
after the exposure ended (Lowe, et al., 1971). A second group of shrimp
was exposed to 0.1 ppb of technical mirex in flowing seawater for 3
weeks. Only 11 percent (4 of 36) of the shrimp died during the 3-week
exposure, but several more showed symptoms of mirex poisoning with 9
dying during the 2-week posttreatment period in mirex-free water. The
juvenile pink shrimp clearly exhibited the phenomenon of delayed
mortality.
Tagatz (1976) designed an experimental estuarine ecosystem
consisting of turtle grass (Thalassia testudinum), grass shrimp
(Palaemonetes vulgaris) and pinfish (Lagodon rhomboides) to determine the
distribution and biological effects of mirex. Sublethal concentrations
were used in tests to assess the effects of mirex in terms of an
alteration of predator-prey interactions. The experiments provided data
on grass shrimp survival after one, two, and three days of predation by
pinfish. More deaths due to predation occurred in the mirex-treated
tanks. In all experiments, an alteration of predator-prey could be
interpreted as an alteration of normal behavior of either shrimp or
pinfish by mirex. The author believed that the behavior of only the grass
shrimp was altered.
Adult lugworms (Arenicola cristata) were exposed to mirex bait
granules (0.3 percent active ingredient) for 30 days and observations
were made for an additional 45 days to determine the effects of mirex on
the activity of this benthic organism (Schoor and Newman, 1976). Egg
masses were deposited during days 4 and 23 of the exposure. Free-swimming
juveniles and juveniles burrowing in the upper layers of the substrate of
78
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the aquarium were observed. Observed feeding behavior and general
activity were considerably less among the mirex-exposed organisms
compared with those of the controls. Overall, low concentrations (0.062
to 0.003 ppb) of mirex in water decreased behavioral activity as measured
by surface activity.
On day 75 (end of the experiment), reduced activity was observed
among the experimentals and controls; that of the exposed worms was much
lower. Considerable destruction of the layered substratum occurred,
especially in the upper half. Mixing due to the burrowing activity of the
worms was indicated. Sand samples taken from the top of the substratum
contained 0.54 ppb mirex (dry sand); from the middle, 0.34 ppb; and from
the bottom, 0.08 ppb. In contrast, in the absence of worms, mirex residue
in the same substratum was found only in the top 2 cm (about 1.5 ppb)
after a 17-day exposure'to similar concentrations of mirex in water
(average of 0.025 ppb). This definitely indicates that the feeding and
burrowing activity of Arenicola can affect distribution of mirex in the
substrate. (Mirex accumulation in the worms is described in Section
5.2.1.2.1).
Oxygen consumption of the pond snail, Physa gyrina, exposed for 3
days to very low mirex concentrations (0.008 to 0.07 ppm) leached from
mirex bait increased to a maximum of 62 percent. Oxygen consumption
dropped by 44 percent at the 1 ppm concentration. This initial increase
in oxygen consumption is considered a normal physiological response to
toxic stress (de La Cruz and Naqvi, 1973) It should be noted that the
mirex concentrations employed in this experiment exceeded normal
saturation (0.2-1.0 ppb) by as much as 70 times, and expected
environmental concentrations by at least a factor of 2000.
5.2.1.3 Fish—
5.2.1.3.1 Uptake and accumulation—Mirex residues can usually be
detected in most fish taken from waters near treated areas, including
edible species such as bass, bream, catfish, and mullet. Bass and bream
usually contain less than 1.0 ppm in their edible portions. Wild catfish
and mullet have been found to contain residues as high as 1 to 5 ppm
(Mirex Advisory Committee, 1972).
Hawthorne, et al., (1974) sampled and analyzed commercially raised
catfish from Mississippi and southern Arkansas areas in which mirex has
been used extensively for fire ant control. Fifty samples, including 25
from nonexposed areas, were analyzed. No mirex was found at the detection
level of 0.01 ppm; however, samples from both areas did contain extensive
residues of other chlorinated pesticides (e.g.,.dieldrin, endrin, and DDT
and its analogs). The lack of detectable residues is an indication that
there was not widespread contamination of catfish. These investigators
suggest that mirex is probably one of the least likely of the chlorinated
pesticides to reach humans through consumption of catfish.
79
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In another study, a 1.22-hectare (3-acre) fish pond and surrounding
drainage area were treated with mirex (1.7 g/ac) six days after
fingerling and adult channel catfish (Ictalurus punctatus) had been
released into the pond (Collins, et al., 1973). Wire cages were used to
confine 50 of the larger fish which were periodically fed commercial
catfish food. Uncaged fish fed on organisms (minnows, crayfish, insect
larvae) which inhabited the pond. A buildup of mirex residues occurred in
uncaged fish whereas the larger caged fish acquired no detectable mirex
and only minute levels of mirex were detected in caged fingerlings. Mirex
residues in the uncaged fish were not detectable 5 days after teatment
but began to increase reaching a maximum of 0.65 ppm 6 months after
treatment. Sixteen months after treatment uncaged fish contained 0.44 ppm
mirex.
Collins, et al., (1973) believed that if a true commercial catfish
pond had been used in their experiment, residues would not have been as
high. Routine monitoring by these researchers showed mirex residues
ranging from 0.008 to 2.59 ppm in wild catfish from areas which received
a blanket application of mirex bait, whereas commercially grown fish from
ponds contained no detectable mirex residues.
Before the study by Collins, et al., (1973), minnows (Opsopoeodus
emiliae) and mosquitofish (Gambusia affinis) were the only fish in the
1.22 hectare (3-acre) study pond. These fish contained detectable mirex
residues which decreased substantially one year after the mirex
application, but were still detectable 16 months after treatment. The
mosquitofish contained 0.08 ppm mirex 38 days after treatment, and 0.07
ppm at 16 months posttreatment. Minnows contained 0.11 ppm 38 days after
treatment; 16 months after treatment minnows contained 0.07 ppm.
Mirex bait (0.3 percent) was applied three times at a rate of 1.4
kg/ha to four ponds containing channel catfish (Hyde, et al., 1974). The
first application was made 8 days after fingerling catfish were placed in
the ponds. Catfish and specimens from a natural population of Lepomis
spp. were collected at each subsequent application and about 2-1/2 months
after the final application. Relatively small quantities of mirex were
detected in the catfish subsequent to the three applications. Mirex was
detected in the catfish muscle from treated ponds at 0.01, 0.03, and
0.015 ppm for the first to the third sampling date, respectively. In
catfish fat, the mirex levels were 0.10 ppm 109 days after the second
mirex application and 0.255 ppm 76 days after the third application.
Levels of mirex in Lepomis spp. were 0.01 ppm 107 days after the first
mirex application and 0.06 ppm 109 days after the second application. A
composite sample of Lepomis contained 0.02 ppm mirex 76 days after the
third mirex application.
Hyde, et al., (1974) attributed the relatively low residues to a
commercial diet being fed to the catfish and Lepomis. The higher mirex
level in Lepomis may reflect a tendency of these species to rely on a
natural food supply and, thereby, accumulate more mirex from food
80
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complexes. The relatively high concentration of mirex in catfish fat is
related to the affinity of mirex for lipid material.
Pimentel (197D has cited a study in which bluegills (Lepomis
macrochirus) concentrated mirex to a level of 6.82 ppm when living in
pond water containing 1 ppm mirex.
Lee, et al., (1975) exposed adult striped mullet (Mugil oephalus) to
0.5 ppm mirex for 96 hours in a continuous-flow bioassay system. Mirex
became most concentrated in the visceral organs. The levels of mirex from
the 96-hour samples were: 21.5 ppm (wet weight) from viscera; 2.0 ppm
from hearts and gills; and 1.4 ppm from skin and muscle. Exposures of
juveniles and adults to 0.01 to 10.0 ppm mirex in a continuous-flow
bioassay system resulted in higher residue levels in the adults (Table
5.3). This is presumably due to the higher proportion of body fat in
adults than in juveniles. The amount of mirex in the fish increased with
increasing mirex concentration in test water.
Twenty-five juvenile pinfish lived for 5 months on a diet that
contained approximately 20 ppm technical mirex. They exhibited no
symptoms of poisoning but concentrated high residues (30 to 40 ppm) of
mirex in body tissues. The fish contained an average of 18 ppm mirex 8
weeks after the exposure ended which indicates that mirex is not easily
metabolized by juvenile pinfish (Lowe, et al., 1971).
5.2.1.3.2 Effects—The limited data on the effects of mirex on fish
concern growth, oxygen consumption, and pathologic developments.
The effects of mirex on bluegills (Lepomis macrochirus) and goldfish
(Carassius auratus) were studied in three experiments in which the fish
were exposed either by feeding them a mirex-treated diet, or by treating
the holding ponds with a mirex formulation (Van Valin, et al., 1968).
There were no mirex-related mortalities among bluegills from single mirex
applications (0.0013 and 1.0 ppm) to holding ponds. However, the number
of fish remaining at the end of this first experiment in each pond was
well below the theoretically possible 380 fish. Pathologic examinations
did not reveal any histologic lesions associated with mirex applications.
Goldfish mortality was noted throughout the second experiment which
also involved mirex treatment (0.1 and 1.0 ppm) of holding ponds. The
remaining goldfish were suffering from a mycobacterial infection. Those
that died were emaciated, lacked the slime layers; had roughened skin
with many protruding scales, and exhibited edematous gill changes. In
addition, a granulomatous kidney lesion, first noted in a single specimen
28 days posttreatment in the 1.0 ppm mirex-treated pond, gradually
increased until it was seen in 75 to 100 percent of all specimens by day
224. The severity of infection in individual goldfish was closely related
to the treatment level. Gall bladders were also distended to two or three
times the circumference of those from fish from the control ponds (Van
Valin, et al., 1968).
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TABLE 5.3. CONCENTRATION OF MIREX ACCUMULATED BY STRIPED
MULLET EXPOSED TO MIREX IN WATER FOR 9f> HOURS
IN A CONTINUOUS-FLOW BIOASSAY SYSTEM3'
Mirex Concentration Mirex Residue,
in Water, ppm ppmc»
Age Group
Juvenile
Adult
Added
0.01
0.1
1.0
10.0
0.01
0.1
1.0
10.0
Measured
0.010
0.104
1.108
5.180
0.012
0.107
1.033
9.540
Mean
0.17
0.85
3.90
17.81
0.38
1.02
6.15
37.30
S.D.
0.02
0.31
0.16
2.47
0.07
0.17
1.91
4.83
aSource: Lee, et al. (1975). Reprinted, with permission,
from Bull, of Environmental Contamination and Toxicology.
(c) Springer-Verlag New York, Inc. (1975).
Number of fish used for analysis: 10 juveniles, and
2 adults per replicate aquarium.
Q
Concentration in mullet expressed as whole-body wet weight.
Duplicate samples per replicate were taken for analysis.
Mean values were obtained with the data from eight separate
analyses for each concentration.
82
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There was no relationship found between growth and degree of
exposure in the experiments involving holding pond treatments. Growth was
very slow among bluegills and the average weight of goldfish declined.
Exposure to mirex had no apparent effect on the spawning success of fish
in either experiment.
Mortality in the feeding experiment was not related to the level of
exposure. No morphologic or systemic changes appeared to be associated
with the exposure to mirex. For bluegills fed the highest level of mirex
(5 ppm) growth was affected. Their average weight was 18.3 grams 168 days
after treatment, as compared with 27.0 and 23.5 grams, respectively, at
the 1- and 3-Ppm treatment levels for the same time period. Parasitism
was a problem with many of the fish exposed to mirex through feeding.
However, there was no apparent relationship between the level of mirex
intake and degree of parasitism (Van Valin, 1968).
The longer channel catfish were exposed to mirex, the greater the
observed mean weight disparity (Hyde, et al., 1974). Catfish from ponds
that had received three applications of 0.3 percent mirex bait at the
rate of 1.4 kg/ha weighed an average of 10.8, 16.8, and 40.8 g less than
fish from untreated ponds.
Mosquito fish (Gambusia af finis) and bluegills (Lepomis macrochirus)
were exposed to mirex leached from fire ant baits. Both Gambusia and
Lepomis exhibited insignificant increases in oxygen consumption after 3
weeks exposure in water containing 1 ppm mirex. Oxygen consumption by
mirex-treated fish decreased slightly from the fourth week of exposure
and stabilized beginning the fifth week for Lepomis and on the seventh
week for Gambusia. As stated earlier an initial increase in oxygen
consumption is considered to be a normal physiological response to toxic
stress (de La Cruz and Naqvi, 1973)-
Young striped mullet juveniles (Mugil cephalus), 20 to 43 mm, were
more susceptible to mirex exposure than older juveniles, 70 to 150 mm, or
adults, 260 to 380 mm (Lee, et al., 1975). Exposures to mirex levels of
0.01, 0.1, 1.0, and 10.0 ppm during 96-hour continuous-flow bioassays
resulted in no mortalities among older juveniles and adults. For young
juveniles, mortality was higher in the two intermediate concentrations
(0.10 and 1.0 ppm mirex) 26.9 percent and 32.1 percent. Concentrations at
either extreme produced less mortality; 0.01 ppm resulted in 6.4 percent
mortality and 10.0 ppm resulted in only 9 percent mortality. The authors
were unsure whether these results were a result of a specific action of
mirex on striped mullet or due to experimental variation.
5.2.1.4 Food Chains-
Prom the data currently available, it is evident that mirex is
reaching some nontarget organisms as a result of previous large-scale
applications for fire ant control. It is also apparent that mirex can be
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transferred through simple two-level food chains established in the
laboratory (Lowe, et al., 1971). Grass shrimp (Palaemonetes pugio and P_._
Vulgaris) were individually fed one particle of mirex bait in standing
seawater. Those which died (more than 50 percent in 96 hours) were later
fed to juvenile blue crabs being held in compartmented, flowing seawater
aquaria. All the crabs died within 14 days after feeding on the
contaminated shrimp. The number of shrimp eaten by each crab ranged from
one to four. A pooled sample of ten grass shrimp carcasses contained 1.1
ppm (2.5 g) of mirex while a pooled sample of seven crabs contained 0.16
ppm (1.9 g) of mirex. Lowe, et al., also found that juvenile blue crabs
accumulated mirex residues after having fed on fish containing the
insecticide (Section 5.2.1.2.1).
The food chain also appears to be the mode of transport of mirex in
natural populations. Collins, et al., (1973) treated a 1.22-hectare (3
acre) fish pond and the surrounding drainage area with mirex (1.7 g
mirex/ac). They found a buildup of mirex residues in uncaged channel
catfish (Section 5.2.1.3.1) whereas only minute levels of mirex were
detected in the caged fingerling catfish. The explanation for such an
occurrence was that caged fish which were fed a diet of commercial
catfish food, did not have a ready access to the natural food chain
(minnows, crayfish, insect larvae). Had the uncaged fish obtained their
residues by directly feeding on mirex bait granules, residues would have
been quite high soon after treatment and would have decreased with time.
Instead, mirex residues were not detectable 5 days after treatment, but
then gradually increased with time, reaching a maximum concentration six
months after treatment, and were still present 16 months after treatment.
The data from this study and that of Hawthorne, et al., (1974) show that
mirex is unlikely to reach humans through the consumption of commercially
raised catfish.
Collins, et al., (1974) monitored accumulation of mirex residues
following application of mirex bait and corroborated the findings of
earlier studies which suggested that the source of mirex residues in fish
is through the food chain rather than through direct ingestion of the
bait pellets. As expected, predatory species of fish such as largemouth
bass contained higher mirex residues than did omnivorous species such as
brown bullheads and sunfish. Gopher tortoises and other strictly
herbivorous species contained significantly less mirex than did either
omnivorous or carnivorous species. Regardless of trophic levels, the
authors found that residues in most animals peaked 1 to 3 months
following bait application and decreased afterward.
Hyde, et al., (1973a) presented disturbing evidence about the
accumulation of mirex in aquatic and terrestrial food chains. An area
under investigation in Louisiana received six applications of mirex bait
at 1.4 kg/ha (1.25 Ib/ac) over a 4-year period. Aquatic plants in this
area contained negligible amounts; snails, crayfish, and fish, 0.01 to
0.75 ppm; soft-shell turtle fat, 24.8 ppm; and birds, 1.2 to 1.9 ppm;
while the fat of vertebrates (raccoons) at the end of the food chain
contained up to 73-9 ppm. The environmental significance of mirex
84
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residues in nontarget species is for the most part unknown. Mirex was
detected in animal tissues at concentrations as high as 0.70 ppm in
several species that are commonly used for human consumption. Those
species include bluegills, chain pickerel, and quail.
Metcalf, et al., (1973) reported a study in which a model ecosystem
was set up in an aquarium using a terrestrial-aquatic interface.
Radiolabeled mirex bait was applied to sorghum seedlings in the
terrestrial portion at the rate of 1.0 Ib per acre (1.1 kg per hectare).
Caterpillars fed on the seedling leaves until consumed; feces and the
caterpillars were allowed to contaminate the aquatic portion which was
stocked with algae, snails (Physa), Daphnia, mosquito larvae, and fish
(Gambusia). The ecosystem was maintained for 33 days in an environmental
chamber. The mirex was very stable, having a biodegradation index of
0.0145 and 0.006 in fish and snail at the end of the 33 day study.
Ecological magnification (EM) values were 219 for fish and 1165 for snail
(water equals 1). Bioconcentration results from the organochlorine's high
lipid solubility and low water solubility. The high water insolubility is
likely the driving force in lipid storage.
Mirex may be bioaccumulated in aquatic organisms directly from the
water. EM factors for Daphnia, mosquito larvae, and fish in water with
similar concentrations as the model ecosystem were 2200, 210, and 530,
respectively. Mirex was not metabolized by the caterpillars. Mirex
residue levels, as well as rates and direction of transfer in the natural
food chain, are difficult to interpret or predict for several reasons:
(1) Numerous organisms (e.g., omnivores, detritus feeders,
filter feeders) cannot be classified into traditional
trophic levels. Feeding habits may change from larval
stage(s) to adult and many organisms may be opportunistic
feeders as adults.
(2) Certain species may move considerable distances (e.g.,
marsh birds, raccoons, blue crabs) and carry residues
with them.
(3) Tidal flushing, storms, and hurricanes can suspend sediments
in freshwater lotic and lentic systems and in estuaries.
Spring turnover in lakes may also cause resuspension of
mirex-bearing sediments.
Mirex residues measured in the past may be partially con-
fused with the polychlorinated biphenyl, Arochlor 1260, and/
or Dechlorane, which is chemically identical to mirex (Mirex
Advisory Committee, 1972).
85
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5.2.2 Kepone
5.2.2.1 Algae and Phytoplankton—
Few data are available on the uptake and/or effects of Kepone on
algae and phytoplankton. Walsh, et al., (1976) exposed marine green algae
(Chlorococcum sp. and Dunaliella tertiolecta) and diatoms (Nitzschia sp.
and Thalassiosira pseudonana) to Kepone to determine its effects on
growth and its uptake by the phytoplankters. In the uptake studies,
twelve cultures of each algae were grown in full-nutrient media for 6
days. These algae were then exposed to 100 ppb Kepone for 24 hours.
To determine the effects on growth, algae were grown in an
artificial seawater medium of 30 parts per thousand salinity with full-
and half-nutrient strengths. Technical grade Kepone in 0.1 ml acetone was
added to the media each day for 7 days. Each Kepone exposure was
performed three times. After a 21-hour exposure to 100 ppb Kepone,
residues associated with the algae in ppm (wet weight), were:
Chlorococcum sp., 80; P. Tertiolecta, 23» Nitzschia sp., 11; T^
pseudonana, 52. The calculated EC-0 values (Kepone concentrations which
reduced growth by 50 percent after seven days' exposure) in ppm were:
Chlorococcum sp.; 0.35; D. tertiolecta, 0.58; Nitzschia sp., 0.60;
Thalassiosira pseudonana, 0.60.
Reductions of phytoplankton populations by short (4 hours) or longer
(24 hours) exposures to Kepone concentrations ranging from 0.35 to 1.0
ppm could disturb or destroy the lowest level of the aquatic food chain
which would, in turn, have a direct effect on productivity at other
levels of the food chain. Kepone may be passed along the food chain to
man as a result of being accumulated in algae. Consequently, there is the
potential for Kepone being bloconcentrated in harmful proportions in
man's food source (Section 5.2.2.4).
5.2.2.2 Aquatic Invertebrates—
5.2.2.2.1 Uptake and accumulation—Invertebrates bioconcentrate
Kepone to dangerously high levels. Bloaccumulatlon data for various
aquatic invertebrates are presented in Table 5.4. Schimmel and Wilson
(1976) found that grass shrimp (Palaemonetes pugio) and blue crabs
(Callineotes sapidus) concentrated Kepone when exposed to various levels
during 96-hour flow-through bioassays. It should be noted that none of
the exposures was representative of realistic environmental levels. The
lowest Kepone exposure of 12 ppb resulted in whole-body Kepone residues
of 5 ppm wet weight in grass shrimp. A whole-body Kepone residue of 0.85
ppm wet weight was detected in blue crabs exposed to 110 ppb (the lowest
concentration in the experiment). Some of the published data on blue
crabs appear to be misleading. For example, blue crabs have been obtained
from the James River with as much as 6 ppm Kepone in their tissues. Yet,
in the laboratory such levels have only been achieved when exposed to
unrealistically high concentrations. Presumably crabs in their natural
86
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TABLE 5.4. ACCUMULATION OF KEPONE BY SELECTED AQUATIC INVERTEBRATE SPECIES
Species Tissue
Grass shrimp Whole body
(Palaemonetes pu$io)
Opossum shrinp Whole body
(Mysidopsis bahia)
Blue crab Whole body
(Callinectes sapidus )
Oyster Whole body
(Crassostrea virginica )
Accumulated Level,
ppm (wet weight)
5.1-94.0
0.13
5.2
0.2
5.5
0.85-1.7
0.3
3.6
Bioconcentration
Exposure Conditions
Factor Concentrations
Average Range
698 (425-933)
5,127
11,425
5,962
13,473
8.1 (6.2-10,4)
9,354
9,278
ppb
12-121
0.023
0.4
0.026
0.41
110-210
0.03
0.39
Time
96 hours
28 days
28 days
21 days
21 days
96 hours
19 days
21 days
* Adapted from Bahner, et al., (1976)
'Seawater.
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habitats obtain much of the pesticide from food or from sediments where
they burrow.
Bahner, et al., (1976) reported high bioconcentration factors of
13,^70; 11,430 and 9,280, respectively, for the opossum shrimp (mysid),
grass shrimp, and oyster (see Section 5.2.2.4; Tables 5.4 and 5.5). The
difference between the shrimp species and the oyster in the
bioconcentration of Kepone has been attributed to depuration rates.
Depuration of Kepone from oysters has been found to be rapid while for
shrimp this process is relatively slow. Concentration factors for adult
mysids (Mysidopsis bahia) exceeded 14,000 X within 11 days of exposure to
0.43 ppb, but averaged 6400 X during a 21-day exposure to 0.26 ppb Kepone
(Nimmo, et al., 1976).
5.2.2.2.2 Effects—Kepone is acutely and chronically toxic to
estuarine species under controlled exposure conditions in the laboratory.
Nimmo, et al., (1976) conducted life-cycle bioassays on the mysid,
Mysidopsis bahia, to determine the acute and chronic toxicities of
Kepone. The 96-hour LC,-0 for Kepone in the mysid was 10.1 ppb at 10 to 16
parts per thousand salinity whereas the 19-day life-cycle LC,.Q was 1.4
ppb at 10 to 20 parts per thousand salinity.
The life-cycle test was long enough for the production of several
broods. The average number of young per female at 20 days was 8.9 upon
exposure to 0.39 ppb Kepone compared with 15.3 among the controls. Those
24- and 48-hour juveniles which were exposed to 0.39 ppb Kepone did not
grow as rapidly as did the controls within the first 15 days. Even those
female mysids exposed to as little as 0.072 ppb Kepone were shorter than
controls. Also body size is correlated with reproductive success. It has
been established with thirteen crustacean species (five of which are
mysids) that the number of eggs produced is directly related to body
length (Nimmo, et al., 1976).
In nature the loss of mysids due either to the direct toxic effects
of Kepone and other pollutants or to the indirect effect on their growth
or population size could affect the food supply of many fishes. Mysids
are apparently very important components in the food chain of fishes and
this might have a direct influence on fish productivity.
Schimmel and Wilson (1976) conducted flow-through bioassays to
determine the acute effects of Kepone on two representative crustacean
species found in the James River estuary. The representative 96-hour LC5Q
values were: grass shrimp, 121 ppb and blue crab, 210 ppb. The symptoms
of Kepone poisoning exhibited by those species were lethargic behavior
followed by a loss of equilibrium. The authors cited a study in which the
48-hour flow-through bioassay EC5Q value (based on mortality or loss of
equilibrium for shrimp and craBs) for Kepone toxicity was found to be 85
ppb for brown shrimp (Penaeus aztecus) exposed at a seawater temperature
of 14 C. Twenty percent of the blue crabs exposed to 1000 ppb Kepone died
in 48 hours.
-------
Kepone was found to be among the chlorinated hydrocarbons that are
least toxic to adult brown shrimp (Penaeus aztecus). A 96-hour EC™ value
based on a loss of equilibrium was 0.70 ppm at 30 C. Exposure of juvenile
blue crabs (Callineotes sapidus) to 1.0 ppm Kepone for 24 hours at 29 C
produced only irritation (U.S. Environmental Protection Agency, 1976c).
Fiddler crabs (Uca pugilator) were exposed to 320, 560, 750, 1000,
and 1600 ppb Kepone during 24-, 48- and 96-hour static bioassays
(Heitmuller, 1975). The 24-hour LC5Q value was greater than 1600 ppb and
that for 48 hours was 1345 ppb. Mortality ranged from zero percent in
nominal test concentrations (of 320 to 750 ppb) to 70 percent in 1600 ppb.
Kepone was found to be comparatively toxic to oysters, causing a 50
percent decrease in shell growth during a 96-hour exposure. The EC,-0
values were 0.057 ppm at 14 C and 19 parts per thousand salinity, ana
0.015 ppm at 31 C and 25 parts per thousand salinity (U.S. Environmental
Protection Agency, 1976c). A study by Butler (1963) showed 48-hour ECt
values (based on the inhibition of shell deposition) to be 57 and 15
for eastern oysters (Crassostrea virginica) at seawater temperatures of
14 and 31 C, respectively.
5.2.2.3 Fish—
5.2.2.3.1 Uptake and accumulation—Laboratory exposures of fish
species to Kepone at the EPA Laboratory at Gulf Breeze, Florida, showed
Kepone to be bioaccumulative and persistent. Tissue residue analyses
performed in toxioity bioassay studies by Schimmel and Wilson (1976)
indicate that sheepshead minnows and spot (a commercially important food
fish) bioconcentrate Kepone to excessively high levels. The authors
determined that these fishes depurate Kepone at a rather slow rate as
compared with that for the oyster. This accounts, at least in part, for
the high Kepone levels. After three or more weeks in Kepone-free water,
only 30 to 50 percent of the accumulated Kepone was lost.
Bioconcentration factors were similar in both fish species. A
bioconcentration factor of 1577 was reported for the sheepshead minnow
upon exposure to a Kepone concentration of 7.1 ppb. The associated
whole-body Kepone residue was 11.2 ppm wet weight. For spot, a
bioconcentration factor of 1133 was equivalent to a whole-body residue of
1.7 ppm upon exposure to a Kepone concentration of 1.5 ppb.
Bahner, et al., (1976) found that spot bioconcentrated Kepone from
seawater containing 0.029 ppb to a level of approximately 0.21 ppm.
Sheepshead minnows contained approximately 0.54 ppm Kepone after 28 days
exposure to seawater containing 0.05 ppb. The residues were higher in
female sheepshead minnows (0.35 ppm) than in males (0.25 ppm). Kepone
accumulated in edible fillets to near the whole-body concentrations in
sheepshead minnows and spot. Therefore, one of the largest reserves (22
percent) of Kepone in absolute weight is in the edible portion of the
contaminated fish.
89
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Hansen, et al., (1976) found that concentration factors for adult
sheepshead minnows averaged 2500 following exposure to Kepone
concentrations ranging from 0.16 to 24 ppb. Again, the bioconcentration
of Kepone was greater in female sheepshead. Kepone residues in dead fish
were (exposure level in parentheses) 17 ppm (7.8 ppb); 10 ppm (1.9 ppb);
and 3-4 ppm (0.8 ppb). Kepone residues in sheepshead eggs were similar to
those in the female fish. Concentration factors in juvenile fish averaged
7200. Juvenile progeny of adult sheepshead exposed to 1.9 ppb Kepone,
though hatched and grown in Kepone-free water, contained 0.13 ppm. Kepone
concentations in juveniles increased with increased concentrations of
Kepone in water.
5.2.2.3.2 Effects—Kepone was found in one study to be among the
least toxic chlorinated hydrocarbons to certain estuarine fish. For
juvenile white mullet (Mugil curema), the 24-hour LC _ was 0.5 ppm at 31
C; the 48-hour LC^Q was 0.055 ppm. The longnose klllifish (Fundulus
similis) was found to have a 24-hour LC__ of 0.3 ppm at 31 C and a
48-hour LC_. of 0.084 ppm (U.S. Environmental* Protection Agency, 1976c).
t>u
Hansen, et al., (1976) investigated the toxicity of Kepone to
embryo, fry, juvenile and adult sheepshead minnows (Cyprinodon
variegatus) using intermittent-flow bioassays. Thirty-two adult males and
thirty-two adult females were exposed to 0.16, 0.80, 1.9f 7.8 and 24 ppb
of Kepone for 28 days. Also, 10 fish were exposed to 0.05 ppb for 4
weeks. All fish exposed to 7.8 and 24 ppb died by day 15. Seventy-eight
percent survived at 0.8 ppb and 20 percent at 1.9 ppb, and these
exhibited symptoms of Kepone poisoning. Symptoms of poisoning were
related to concentration and duration of exposure. They progressed from
scoliosis, darkening of the posterior one-third of the body, hemmorhaging
near the brain and at the anterior point of darkening, edema, fin rot,
uncoordinated swimming, and cessation of feeding. Symptoms increased in
severity and frequency before death. This occurred from 5 to 8 days after
initial exposure.
Surviving adults were spawned, and embryonic development, hatching,
and survival and growth of fry and juveniles were monitored in a 36-day
exposure. The effects of exposure of progeny to 0.08 to 33 ppb Kepone
were less severe than those observed with adult fish exposed to similar
concentrations. The 36-day LC__ to juveniles was 4.9 ppb and the 28-day
LCj-Q to adults was 1.1 ppb. The average standard length of juvenile fish
wa% significantly reduced by exposure to 0.08 ppb Kepone; some fish
developed scoliosis. Embryo survival was significantly reduced; 91
percent in controls and at 0.08 and 0.18 ppb Kepone as compared with 83
percent at 0.18 ppb Kepone. A significant number of embryos from adult
fish exposed to 1.9 ppb Kepone developed abnormally and died even when
incubated in Kepone-free water. Fry from embryos exposed to 6.6 or 33 ppb
Kepone were visibly affected within 24 hours of .hatching. Symptoms of
poisoning in fry less than 1 week old included diminished activity, loss
of equilibriium, cessation of feeding and emaciation. Fry more than 1
week old had symptoms identical to those in adult fish except for a lack
of hemorrhaging and the presence of edema.
90
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Sixty percent of juvenile fish which survived 36 days of exposure to
0.08 ppb Kepone had scoliosis and blackened tails. In Kepone-free water
scoliosis persisted for more than ten days. These fish, spawned from
adult sheepshead previously exposed to 0.05 ppb, were exposed to Kepone
longer than those from embryo, fry, and juvenile exposures. These results
illustrate very well how the long-term effects of Kepone on juvenile fish
have been underestimated.
The predicted 96-hour LC values for exposures to Kepone of
bluegills (Lepomis macrochirus) ana rainbow trout (Salmo gairdneri) are
0.051 ppm and 0.036 ppm, respectively. The highest predicted
concentration at which there was no discernible effect during a 96-hour
bioassay was 0.024 ppm for bluegills and 0.014 ppm for rainbow trout
(Bentley, 1974). The same author observed an 80 percent mortality in 96
hours at 0.065 ppm and a 48-hour LC 5Q of 0.180 ppm for bluegills. In 96
hours, there was an 80 percent mortality among rainbow trout at 0.037 ppm
Kepone and total kill at 0.100 ppm during the 48-hour bioassay.
The U.S. Environmental Protection Agency (1976c) reviewed several
toxicity studies involving Kepone and fish. The length of time redear
sunfish (Lepomis microlophus) were exposed to Kepone had a much more
pronounced effect than temperature. Rainbow trout are about ten times
more susceptible to Kepone than are redear sunfish. The 24-hour LC,_0 for
rainbow trout is 0.066 ppm, while the 24-hour LC _ for the redear sunfish
is 0.62 ppm.
Kepone, applied at rates of 0.11 and 0.56 kg/ha (0.1 and 0.5 Ib/ac)
on shallow 0.025-hectare (1/16-acre) ponds, caused only 2 and 18 percent
mortality, respectively, in populations of the mosquitofish (Gambusia
affinis) after 24-hour exposures (U.S. Environmental Protection Agency,
1976c).
In vitro experiments (Desaiah and Koch, 1975) which tested the
effects of Kepone on brain ATPase activity in channel catfish (Ictalurus
punctatus) demonstrated significant inhibition of oligomycin-sensitive
(mitochondrial) Mg , oligomycin-insensitive Mg and Na^-K* ATPases with
increasing concentrations of Kepone and its reduction product
decachloropentacyclo-decan -5-ol (DCPD). Oligomycin-insensitive Mg *
ATPase activity was somewhat less sensitive to inhibition by Kepone.
Comparable concentrations of Kepone (1.25 and 2.5 micro molar) produced
25-7 and 36.7 percent inhibition. The authors concluded that inhibition
of the type noted above could probably result in physiological impairment
due to a reduction in energy supply.
5.2.2.4 Food Chains-
Accumulation, transfer, and loss of Kepone in estuarine food chains
were studied in laboratory bioassays. Kepone was bioconcentrated by
oysters (Crassostrea virginica), mysids (Mysidopsis bahia), grass shrimp
(Palaemonetes pugioTT"sheepshead minnows (Cyprinodon variegatus), and
91
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spot (Leiostomus xanthurus), from concentrations as low as 0.023 ppb in
seawater (Bahner, et al., 1976). Bioconcentration factors for Kepone in
the species are summarized in Table 5.5. All species had equilibrated
tissue concentrations of Kepone within 8 to 17 days after beginning
exposure to the pesticide.
Depuration of Kepone from oysters was rapid, with nondetectable
concentrations ( 0.02 ppm) being found within seven to twenty days after
exposure to Kepone ceased. Clearance of Kepone from grass shrimp and fish
was relatively slow, with tissue Kepone residues decreasing 30 to 50
percent in 24 to 28 days.
Oysters, fed the green alga Chlorococcum which contained an average
of 34 ppm Kepone, bioaccumulated 0.21 ppm Kepone (wet tissue) in 14 days
and in Kepone-free water depurated Kepone to below detectable
concentrations within 10 days. Residues in composite samples of feces and
pseudofeces from these oysters averaged 1.78 ppm Kepone (dry weight).
Spot accumulated Kepone when fed live mysids that had grazed on
Kepone-laden brine shrimp. Mysids which consumed brine shrimp with Kepone
residues of 0.05 or 2.33 ppm attained whole-body Kepone residues of 0.023
(estimated) or 1.23 ppm, respectively, within 72 hours. Kepone residues
in the spot approached the concentration of their food; at the lower
concentration, Kepone residues that were below detection in the living
food organisms accumulated in the predator to detectable concentrations
of 0.02 ppm within 30 days.
The maximum overall accumulation and transfer of Kepone or
food-chain potential from water to algae and finally to oysters was 2.1,
but the transfer potential (i.e., the transfer of Kepone from one trophic
level to the next) from algae to oysters was only 0.007- These data
indicate that transfer and retention of Kepone from algae by oysters were
inefficient. Conversely, the food-chain potential from water to brine
shrimp to mysids and finally to fish ranged from 3-9 to 10.5. The
transfer potential from brine shrimp to mysids was 0.53 and from mysids
to spot was 0.85 indicating that much of the Kepone was being transferred
through these trophic levels (Bahner, et al., 1976). The efficiency of
Kepone transfer to spot suggests a great potential for Kepone transfer to
humans via the consumption of spot.
5.3 TERRESTRIAL BIOTA
5.3.1 Terrestrial Invertebrates
5.3-1.1 Mirex—
The Mirex Advisory Committee (1972) reported that mirex residue
levels are extremely low (0.05 ppm) or nondetectable in phytophagous
animals selected from mirex-treated areas. Most terrestrial invertebrates
have been found to contain less than 0.1 ppm but general scavengers such
as crickets and cockroaches, which may consume mirex bait directly, have
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TABLE 5.5. BIOCONCENTRATION FACTORS FOR SELECTED SPECIES
EXPOSED TO MEASURED CONCENTRATIONS OF KEPONE
IN WATER3
Species
Chlorococcum sp. ,
alga
Grasses trea virginica,
oyster
Crassostrea virginica,
oyster
Artemia salina,
brine shrimp
Artemia salina,
brine shrimp
Mysidopsis bahia,
mysid
Mysidopsis bahia,
mysid
Palaemonetes pugio,
grass shrimp
Palaemonetes pugio,
grass shrimp
Cyprinodon variegatus ,
sheepshead minnow
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Leiostomus xanthurus,
spot
Concentration,
ppb
100
(static)
0.03
0.39
5.00
(static)
100
(static)
0.026
0.41
0.023
0.4
0.05
0.029
0.4
1.5
3.4
4.4
12.0
16.0
Length
of Exposure
24 hours
19 days
21 days
48 hours
48 hours
21 days
21 days
28 days
28 days
28 days
30 days
30 days
96 hours
96 hours
96 hours
96 hours
96 hours
Mean
Bioconcentration
Factor
340
9,354
9,278
10
23
5,962
13,473
5,127
11,425
7,115
3,217
2,340
1,120
941
1,591
900
1,050
Adapted from Bahner, et al., (1976).
93
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been reported to contain mirex residues ranging from 10 to 30 ppm.
Predaceous arthropods such as spiders have been found to contain residues
higher than those in general invertebrate populations. Spiders may
contain in excess of 1.0 ppm mirex 1 year after treatment. Although a
decline in populations has been reported for crickets, oil-loving ants
and ground beetles following mirex bait application, there is no evidence
available to indicate that these populations are permanently affected
(Mirex Advisory Committee, 1972).
Lee (1974) reported the results of an investigation in which mirex
was experimentally applied to oak and dogwood leaf litter. Two forms were
used, corncob grit bait and spray—at the normal application rate of 1.7
g mirex per acre and at ten times the normal rate to evaluate its effects
on ecological processes. Ants were essentially removed from bait and
concentrated spray areas up to 79 days after treatment; centipedes were
decreased on these same areas. The low spray treatment did not affect
ants. Spiders, millipedes, beetles, and scorpions were not affected. No
patterns of change in microarthropod populations were detected.
Decomposition of leaf litter was accelerated in all treatments when
compared to control areas. The author speculated that mirex may have
accelerated decomposition through its ability to induce mixed-function
oxidase systems in bacteria and fungi. These enzymes are responsible for
the breakdown of some xenobiotics. The synthesis of these enzymes may
have allowed faster metabolism of the plant inhibitor tannic acid,
resulting in an early boost in the decomposition process.
Atkins, et al., (1975) classify mirex as moderately toxic; it can be
used around bees if dosage, timing and method of application are correct,
but should not be applied directly to bees in the field or at the
colonies. Mirex has an LD_. of approximately 7-15 microgram/bee.
Extrapolating on the basis7 of the dose mortality curves presented, mirex
could be applied at a rate of up to 3.9 kg/ha (3-5 Ib/ac) without causing
over 20 percent mortality. Similarly, a dosage of 12 kg/ha (10.7 Ib/ac)
would result in approximately 70 percent mortality. Normal application
rates of mirex (4.2 g/ha, 1.7 g/ac) represent less than 0.2 percent of
the 3.5 Ib/acre dosage needed to cause 20 percent mortality.
5.3.1.2 Kepone—
Atkins and Anderson (1962) present evidence that Kepone does not
pose a significant threat to honeybees and predaceous insects. Their
studies indicated that bees from hives exposed regularly to DDT over a
period of 10 years developed a resistance to DDT and, moreover, this
resistance was carried over to a number of other chlorinated
insecticides, including Kepone. A later publication by Atkins, et al.,
(1973) calculated that to cause a 50 percent decrease in honeybee
population, Kepone would have to be applied at 11.65 kg/ha (10.4 Ib/ac).
This dosage amounts to about 5 times the application rate recommended by
the U.S. Environmental Protection Agency (1976) to control the banana
root borer and 10 times that recommended for control of tobaco wireworms.
At the 2.25 kg/ha (2 Ib/ac) level of application, Kepone was not harmful
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to three out of four predaceous insects and arthropods monitored in an
apple orchard.
5.3.2 Amphibians and Reptiles
Extremely little information is available on the toxicity or
metabolism of mirex in amphibians and reptiles. The only available data
come from environmental surveys which monitored mirex accumulation in
non-target organisms following mirex bait application.
Collins, et al., (1971*) sampled 61 species of vertebrates following
a single application of mirex bait. They concluded that reptiles and
amphibians generally accumulated lower residues (0.001-0.828 ppm) than
did birds and mammals. Surprisingly, carnivorous reptiles such as water
snakes, lizards and skunks did not appear to concentrate mirex as did
birds with similar feeding habits. The authors felt that this may be
related to the greater relative volume of food consumed by birds as
compared with the volume consumed by reptiles.
Similar data on Kepone accumulation in amphibians and reptiles are
not available.
5.3.3 Birds
5.3.3.1 Mirex—
5.3.3.1.1 Acute toxicity—Compared to other species, birds are not
extremely sensitive to mirex. The LDgo and LC5Q values shown in Table 5.6
are considerably higher than those for mammals and fish. Naber and Ware
(1965) found that a daily consumption of 300 to 600 ppm of mirex was
necessary to produce weight loss in hens and a significant decrease in
egg hatchability and survival of chicks.
5.3.3.1.2 Subacute toxicity—The U.S. Department of the Interior
Fish and Wildlife Service conducted tests to determine lethal dietary
toxicities of mirex to bobwhite, Japanese quail, ring-necked pheasant,
and mallards (Hill, et al., 1975). The LCgo as used in this procedure is
ppm toxicant (based on active ingredient? in an ad libitum diet producing
50 percent mortality in 8 days (5 days of toxic diet followed by 3 days
of untreated diet). Up to six different dietary concentrations of the
pesticide were used in each test and LC5Q values based upon these
concentrations were determined by means of computerized probit analysis
(Table 5.7). These values seem consistent with those of Table 5.6. In
addition, the toxicity of dieldrin relative to that of mirex (expressed
as the RTD) is one of the highest among 131 pesticide compounds tested in
this study, confirming the findings of rather low acute toxicity of mirex
to birds. Similar subacute toxicity studies by Baetcke, et al., (1972)
indicated that 8 to 81 percent mortality occurred in quail, mallards,
pheasants and oowbirds fed diets containing 200 to 500 ppm mirex for 30
to 111 days.
95
-------
TABLE 5.6. REPRESENTATIVE ORAL
VALUES FOR MIREX*
Exposure ^SO ^5(1
Species route ing/kg ppm
Mallard Oral 2,400
Coturnix Oral ]_Q 000
Pheasant Oral 1,400 to 1,600
a Source: Waters (1976) .
96
-------
TABLE 5.7. DIETARY TOXICITIES OF MIREX TESTED IN 5-DAY DIETS OF YOUNG BOBWHITES,
JAPANESE QUAIL, RING-NECKED PHEASANTS, AND MALLARDS3
Species
Bobwhite
Japanese quail
Ring-necked
pheasant
Mallard
days
14
14
14
10
Number
of
Concen-
trations0
6
1
6
3
LC50d
2511
>5000
1540
>5000
Toxicity Statistics
95% Confidence f
Interval RTD6'
2160-2908. 60.6
20% mortality
;i320-1789 29.3
No mortality
95% Confidence
Interval
49.3 -74.2
24.1 -37.7
aAdapted from Hill, et al., (1975).
Age of birds at start of test.
number of dietary concentrations used in probit analysis.
LCso? ppffl compound (based on active ingredient) in ad libitum diet calculated to produce
50 percent mortality in 8 days (5 days of toxic diet followed by 3 of untreated diet).
eRelative toxicity of dieldrin (RTD) read as: "Dieldrin is x times as toxic as the given
compound as tested".
Dieldrin toxicity statistics are mean values for all comparable dieldrin tests (sample size:
bobwhite, 7; Japanese quail, 15; ring-necked pheasant, 19; 10-day-old mallard, 11; and,
5-day-old mallard, 6).
-------
Waters (1976) examined the distribution pattern of mirex in laying
hens fed 1.06 ppm mirex in the diet. Mirex appeared to be readily
absorbed from the digestive tract and distributed throughout the body. At
27 weeks, highest levels were found in fat, 15.15 ppm; other organ levels
were kidney, 2.16 ppm; liver, 0.49 ppm; and breast, 0.11 ppm. Levels in
all tissues were elevated after 39 weeks of treatment: fat, 24.8 ppm
(»^64 percent increase); kidney, 3.4 ppm («/59 percent increase); liver,
1.9 ppm (r*294 percent increase); and breast, 0.31 ppm («>/l82 percent
increase).
5.3.3.1.3 Metabolism—£yie» et al., (1974b) studied accumulation,
distribution and excretion of C-mirex in quail exposed to up to 30 ppm
mirex in the diet. After 16 months of continuous mirex treatment,
radiocarbon residues in the fat of male quail were almost 200 times
higher than dietary concentrations and showed little tendency toward
reaching a plateau of residue accumulation. Skin consistently showed high
radiocarbon concentrations also. As shown in Table 5.8, other tissues
analyzed revealed much lower radiocarbon than did fat. Male and female
quail exhibited differences in residue patterns. Once the females began
producing eggs (at about 6 weeks of age), residues in all their tissues
were substantially lower than in males. In contrast to males, females
rapidly established an equilibrium between mirex intake and elimination
through the eggs, which resulted in a plateau in all tissues. Female
quail were also considerably more efficient at eliminating existing body
burdens of radiocarbon following cessation of the C-mirex diet. After 3
months, residual radiocarbon in most tissues was reduced bv^at least 75
percent. Male quail excreted at least 40 percent of the C-mirex in a
comparable period. Numerous other studies have documented the importance
of egg-laying as a means of eliminating body burden in female birds
(Ivie, et al., 1974b; Waters, 1976; Foster, 1974).
5.3.3.1.4 Reproductive effects—Significant effects on reproduction
were not seen in bobwhite quail fed 10 to 40 ppm mirex and mallards fed 1
to 10 ppm. Some suppression of egg production occurred in the mallards
but none occurred in the bobwhites. Rapid transmittal of mirex to eggs in
treated birds and a significant accumulation of mirex residues in brains
and carcasses occurred at these dosages (Woodham, et al., 1975). Levels
up to 200 ppm of mirex appeared to be tolerated in laying hens without
adverse effects on various reproductive parameters such as egg
hatchability and chick growth and survival (Waters, 1976). In a similar
study by Hyde, et al., (1973b), mallard ducks fed dosages of 1 and 100
ppm of mirex did not differ significantly from controls on egg
production, shell thickness, shell weight, embryonation and hatchability.
Duckling survival was significantly reduced (P 0.01) in the group fed
100 ppm, however.
Eggshell abnormalities such as thinning in some instances and
thickening in others were a result of dietary mirex exposure (Waters
,1976). The mechanisms by which organochlorines affect eggshell thickness
have not been elucidated but may include (a) stimulation of hepatic
microsomal enzymes which degrade steroids necessay for calcification, (b)
98
-------
TABLE 5.8. 14C RESIDUES IN THE TISSUES OF JAPANESE QUAIL FED 30 PPM OF MIREX-14C IN THE DIET*
vo
vo
Ppm of Mirex Equivalents
Brain
Time
4 days
7 days
14 days
1 month
6 months
12 months
16 months
7 days
14 days
1 month
3 months
6 months
10 months
Male
1.
2.
2.2
3.3
4.9
7.4
7.2
5.0
5.1
5.2
0.4
0.2
0.1
Female
6
5
2.4
3.5
1.4
1.9
2.2
2.3
3.1
1.7
0.5
0.2
0.1
Muscle
Male
4
5
5.6
8.0
50.6
72.8
87.0
45.8
38,2
45.2
14.4
3.5
5.0
Female
.9
.9
5.4
12.4
10.0
7.9
11.4
Removed
6.8
5.9
4.5
1.4
0.5
0.1
Male
Birds
16.7
30.2
55.1
114.4
138.0
Liver
Female
Kidney
Male
Female
Skin
Male
Female
Feathers
Male
Female
on treatment
34.3
47.4
23.5
30.5
55.7
25.5
30.9
from treatment
62.4
52.3
51.2
8.6
6.5
5.4
18.2
19.3
7.1
1.5
0.5
0.1
7
9
12.1
21.1
58.2
64.0
88.9
after 6
52.5
61.0
42.4
4.9
3.5
2.9
.1
.4
12.1
13.3
18.3
10.4
11.6
months
5.9
4.6
2.5
0.6
0.2
0.1
48
62
137.7
233.2
600.5
1495.4
872.8
906.1
1028.3
818.2
765.3
620.1
575.8
.8
.6
180.7
130.4
92.8
99.1
129.0
100.9
77.9
81.1
40.7
19.5
1.4
5
14
15.5
25.7
36.2
196.7
114.8
47.4
51.7
40.9
33.5
29.4
28.4
.9
.7
8.8
30.4
26.5
39.6
33.0
15.8
8.8
14.3
7.3
5.6
1.9
Source: Ivie, et al (1974). Reprinted, with permission, from J. Ag and Food Chem.
American Chemical Society (1974).
Sex of quail could not be determined at this age.
(c)
-------
inhibition of medullary bone deposition, (c) inhibition of the
parathyroid gland, (d) inhibition of the thyroid, (e) inhibition of
calcium from the gut, (f) inhibition of carbonic anhydrase activity in
the avian shell-forming gland, and (g) abnormal stimulation of the of the
nervous system which results in premature ejection of eggs (Foster, 1974).
5.3-3.1-5 Residue accumulations in wild birds—Numerous wildlife
sampling surveys have indicated that birds, as a group, contain
relatively high levels of mirex. Most insect-eating birds collected in or
near a treated area contained mirex residues greater than 1 ppm,
occasionally containing as much as 10 ppm or more. Egg samples from snowy
egrets averaged around 13 ppm. The reproductive consequences of mirex
residues of this magnitude in eggs are not known. A survey of birds
collected from the eastern United States showed mirex residues present
only in those from South Carolina, Georgia, and Florida; in a sample of
eight birds, an average level of 1.32 ppm (lipid weight) was detected. In
starlings, levels of 0.1 to 1.66 ppm mirex have been reported by Waters
(1976).
Birds were also sampled in a survey of mirex residue accumulation
following a single aerial application of mirex bait (Collins, et al.,
1974). Birds accumulated mirex residues at levels in the range of 1 to 8
ppm. The highest concentrations of mirex were detected in loggerhead
shrikes and mockingbirds 3 months after treatment. The authors believe
that these residues reflect the diet of these birds. Interestingly, green
herons did not accumulate high levels of residues as would be expected by
virtue of their position in the food chain. An extensive home range of
the herons could account for the relatively low residue levels if they
derived a large part of their diet from outside the treated area. Birds
whose diets consist primarily of seeds, fruits and vegetable matter, such
as cardinals, Eastern cowbirds and quail, had lower levels of mirex than
the more carnivorous species such as shrikes, meadowlarks and
mockingbirds.
Mirex is a very stable compound chemically and residues in certain
species are remarkably persistent. For example, adult snowy egrets
contained up to 0.64 ppm and nestlings analyzed had up to 3*5 ppm mirex 1
year after treatment with mirex. Insectivorous land birds have been
reported to contain from 0.22 to 9.1 ppm mirex 6 to 12 months after
treatment (Mirex Advisory Committee, 1972).
A very recent study by Kendall et al., (1977) reported on mirex
residues in wild birds. Mirex was aerially applied in early fall to a
state game management area in Hampton County, South Carolina, at the rate
of 1.7 g mirex per acre (in 1.25 lb corncob grit/soybean oil bait). The
area was managed for bobwhite -quail hunting and had a severe fire ant
infest ation.The authors wanted to measure mirex residues in bobwhite
available for human consumption because the birds' food habits allow
frequent contact with the pesticide. Fat and breast muscle tissues were
obtained from birds collected prior to and periodically for nine months
following treatment. Pre-treatment samples contained some residues as a
100
-------
result of a mirex treatment on adjacent land. Post-treatment samples had
up to a fivefold increase in fatty tissue two weeks after the
application; levels averaged 0.23 ppm and 5.1 ppm in breast and fat,
respectively (dry weight). Grasshoppers, which have been known to have up
to 0.7 ppm mirex in treated areas, were a major component of the
bobwhites1 diet. Levels in tissues declined during the winter but
remained above pre-treatment levels. A sharp peak occurred in the spring,
corresponding with insect emergence. Levels in fat remained elevated
during the summer following treatment.
Residues in many of the breast muscle tissues and in all the fat
tissues appear to exceed the EPA guideline of 0.1 ppm (llpid weight)
mirex in meat for human consumption. However, the authors conclude that,
in light of the low lipid weight of bobwhite and the reporting of
residues on a dry weight basis, the residues would contaminate little, if
any, of the human food chain.
Data recently obtained from Canadian researchers (Table 5.9) have
indicated the presence of mirex and other persistent toxic substances in
herring gull eggs from Lakes Superior, Huron, Erie and Ontario
(Alexander, 1976 personal communication). Unlike the previous examples in
which the source of mirex residues was prior mirex bait application, in
the case of Lake Ontario birds, the source is industrial discharges of
mirex which, through uptake by fish, provide a dietary source of mirex
for the gulls. Because they eat large quantities of fish which have
lipid-soluble chemicals such as mirex, herring gulls are very sensitive
indicators of contaminants. While significantly below the levels of Lake
Ontario gull eggs, the detectable concentrations of mirex in herring gull
eggs from the three other Great Lakes does signify widespread
distribution of mirex in this area.
5.3-3.2 Kepone—
5.3.3.2.1 Acute toxicity—Kepone does not appear to be very toxic
to birds as an acute poison. Tucker and Crabtree (1970) reported a single
dose LD of greater than 2400 mg/kg of body weight in a study of 3 to
12-month^-old mallard ducks. DeWitt et al., (1962) determined a dietary
LC value of 400 ppm for young mallards, 600 and 530 ppm for young and
adort bobwhite quail and 600 and 115 ppm for young and adult ringnecked
pheasants. All 7 to 14-day chicks fed 200 ppm Kepone exhibited severe
tremor after 10 days. Japanese quail injected daily with 0.5 mg Kepone
for 10 days exhibited damage to hepatic parenchymal cells (including
disruption of mitochrondria), cellular debris in bile and canaliculi.
Also, a significant increase in phagocytic kupffer cells lining the liver
sinusoids was observed (U.S. Environmental Protection Agency, 1975).
Eroschenko and Wilson (1975) conducted a histological comparison
study of reproductive organs, livers and adrenal glands from control
immature and adult Japanese quail of both sexes and from quail fed 200
ppm of Kepone under two photoperlod regimes. Kepone had an estrogenic
effect on the oviducts of immature females and on the testes of immature
101
-------
TABLE 5.9. MIREX CONTENT OF HERRING GULL EGGS COLLECTED
IN THE GREAT LAKES IN 1974 AND 1975*
Mi rex Concentration, ppm
Location
Lake Superior
Lake Huron
Lake Erie
Lake Ontario
Year
1974
1975
1974
1975
1974
1975
1974
1975
Number of Samples
19
20
20
20
20
22
19
20
Meant
0.80
0.16
0.82
0.27
0.49
0.29
6.18
4.18
Rangec
0.30- 2.56
0.20- 5.20
0.22- 6.82
0.06- 2. .01
0.15- 2.19
0.14- 0.73
2.15-18.6
1.95-10.0
Source: Alexander (1976) personal communication.
b
Geometric means in ppm on wet weight basis.
c
Range based on 10 egg random samples, 1 per clutch, from
2 colonies in each lake.
102
-------
and mature adults. Kepone increased cellular proliferation,
cytodifferentiation and tubular gland formation in the oviducts of
immature quail under both long and short photoperiods. This accelerated
development and maturation of the oviduct did not produce any evidence of
cellular abnormalities or degeneration. No cellular changes were noted in
oviducts of laying (mature) quail. Ovarian tissue from Kepone-treated
quail contained more primary occytes and smaller follicles when compared
with control birds. In the liver, cells from all of the experimental
birds were filled with large, lipid-like inclusions. Likewise, in all
Kepone-treated birds, hypertrophy of adrenal cortical and medullary cells
was seen. A detrimental effect was also recorded in the testes of both
immature and adult quail under a 16 hours of light-8 hours of darkness
light regimen. Distended seminiferous tubules contained watery fluid
which was apparently responsible for the significant change in testes
weight. Since these changes adversely affect spermatogensis, a high
percentage of reproductive failure would be anticipated.
5.3.3.2.3 Metabolism—No data on the metabolism of Kepone in birds
was identified.
5.3.3.2.4 Reproductive effects—Despite the rather low acute
toxicity of Kepone in birds, hazardous effects on reproduction affecting
both male and female birds have been consistently reported in a variety
of species. Degeneration and abnormality of the testes have been observed
in both young and adult males in at least four laboratory studies of
Japanese quail. Pathologic findings in the testes reported earlier by
Eroschenko and Wilson (1975) would indicate decreased spermatogensis and
sperm mobility in quail fed 200 ppm Kepone.
Generally, an "estrogen-like" effect has been observed in both
sexes. In females, this effect is manifested by accelerated sexual
development of immature female birds, while in the males the effects of
Kepone are much more devastating. Male ring-necked pheasants fed Kepone
at 50, 100 or 150 ppm developed adult female plumage accompained by
abnormal testes, malformed sperm, and a high percentage of reproductive
failure (DeWitt, et al., 1962). The exact nature of the "estrogen-like"
effect of Kepone is unknown but Mcfarland and Lacy (1969) have proposed a
two-fold mechanism. First, Kepone stimulates the hypothalamus to increase
follicle-stimulating hormone (FSH). FSH in turn stimulates estrogen
secretion and acts directly as an estrogenic agent.
Naber and Ware (1965) concluded that the addition of 75 or 100 ppm
of Kepone to the diet of hens results in a significant reduction in egg
production. (Mirex on the other hand, did not significantly reduce egg
production at either the 300 or 600 ppm feeding levels). The apparent
hatchablity of eggs was unaffected, but reduced emryonic survival was
observed in the 100 ppm Kepone group. Survival of chicks during a 14- or
20-day period following hatching was also reduced. Only 56 percent of the
chicks from hens fed 75 ppm of Kepone survived; at the 100 ppm feeding
level, none of the chicks survived. Most of the chicks exhibited a
nervous syndrome. Studies of yolk residues showed high insecticide
103
-------
residues still present in eggs 3 weeks following removal of the hens from
the treated diet.
Like DDT and other organochlorine pesticides, dietary Kepone can
cause teratogenic eggshell deposition. Major defects were noted in the
cuticle and vertical crystal layers of the shell when Japanese quail were
fed 225 ppm Kepone for 21 days (U.S.EPA, 1975). Erben (1972) reported
that Kepone caused formation of a peculiar thick layer of aragonite and
vaterite and thickening of the cuticle layer- This increase in the
thickness of the spongy layer leads to blockage of shell pores, resulting
in suffocation of the embryo.
5.3.3.2.5 Residue accumulations in wild birds—The accumulation of
Kepone in wild birds does not appear to have been investigated as yet.
5.3.4 Mammals
5.3.4.1 Comparative Acute Toxicity of Mirex and Kepone—
Gaines (1969) presented data on the acute toxicity (LD(-0fs) for 98
pesticides administered in a single dose by the oral or dermal route to
adult Sherman strain rats. These data for the pesticides Kepone and mirex
(in two formulations) are presented in Table 5.10. The compounds were
formulated so that the different dosage levels of poison could be given
by stomach tube by administering the formulation at a constant rate of
0.005 ml/g body weight. Dermal applications were at a constant rate of
0.008 ml/g body weight. The LD_Q and LD.. values and the lowest dose of
pesticide to kill a rat are given in Table 5.10. The LD1 value is
probably a more realistic measure of the toxic hazard of a compound than
is the LD,-0, and with the LD,-0 value it indicates the slope of the
dose-response line. As can be seen from the table, Kepone has a lower
LD(-0 than mirex when administered orally, yet Kepone and mirex have the
same dermal toxicity. Male and female rats were equally susceptible to
Kepone in oral and dermal administrations; however, mirex is slightly
more toxic to female rats.
5.3-4.2 Mirex—
5.3-4.2.1 Acute toxicity—Mirex administered as an acute oral dose
is not very toxic. The acute LD5Q of mirex for rats lies in the range
from 365 to 740 mg/kg. Gaines ana Kimbrough (1970) reported an acute LD_-
of 365 mg/kg in female Sherman rats. A somewhat lower LD5Q of 740 mg/Rg
in males and 600 mg/kg in females was reported earlier by the same
investigator (Gaines, 1969).
5.3.4.2.2 Subacute and chronic toxicity—The most commonly observed
subacute toxic effects of mirex in mammals are weight loss, increased
liver weight and reproductive difficulties (Gaines and Kimbrough, 1970;
Brooks, 1976; Khera, et al., 1976; Mirex Advisory Committee, 1972).
104
-------
TABLE 5.10. THE ACUTE ORAL AND DERMAL TOXICITY OF KEPONE AND MIREX IN RATSa
Oral, mg/kg Dermal , mg/fcg
Lowest dose to Lowest dose to
LD-Q LD, kill a rat IjQ5Q LD1 kil1 a rat
Compound Males Females Males Females Males Females Males Females Males Females Males Females
Kepone 125 125 92 92 100 125 >2000 >2000 >2000 >2000 >2000 >2000
Mirex 740C 600C 200C 270C 400C 500C >2000 >2000 >2000 >2000 >2000 >2000
Mirexd >3000 >3000 >3000 >3000
aSource: Gaines (1969). Reprinted, with permission, from Toxicology and Applied Pharmacology, (c)
Academic Press, Inc. (1969).
Dosage rate, 0.008 ml/g.
Five percent in corn oil solution.
Twenty percent suspension in corn oil.
-------
Subacute effects were observed in rats at the 5 ppm feeding level
(Gaines and Kimbrough, 1970). Rats fed 5 ppm mirex for 166 days exhibited
minimal, but definite pathological changes in the liver including
slightly enlarged liver cells, vacuolated cytoplasm and occasional
inclusions.
At the 25 ppm feeding level, most of the rats had enlarged
multi-nucleated liver cells with smooth or vacuolated cytoplasm.
Increases in smooth endoplasmic reticulum and free ribosomes, decreased
glycogen and osmiophilic dense bodies, and bile stasis were also reported
at this dosage. The Mirex Advisory Committee (1972) reported similar
findings of enlarged liver and vacuolation of liver cells in rats fed a
dietary dosage of 80 ppm mirex. Deaths were observed at 1280 ppm and
growth suppression occured at 320 ppm. Dogs fed daily dosages of 0, 4,20
and 100 ppm of mirex showed no effects at the 20 ppm dosage level, but
the 100 ppm dose level was lethal.
Chronic exposure to mirex has produced a wide range of effects in
laboratory animals. This insecticide is a documented teratogen (Khera, et
al., 1976) and produces a number of hepatotoxic and enzymatic changes and
reproductive effects (Gaines and Kimbrough, 1970; Byard, et al., 1975;
Kendall, 1974; Baker et al., 1972; and Abston and Yarbrough, 1974, 1976).
While it is suspected that mirex may be a carcinogen, results of two
separate studies have yielded somewhat inconclusive results (Innes, et
al., 1969; Ulland, et al., 1973; Ulland, et al., 1977) due to inadequate
experimental designs and poor survival rates of the test animals. These
effects are more fully discussed in Sections 5.3-4.2.4 through 5.3-4.2.10.
Hayes (1967) has described a technique for calculating a chronicity
factor. This means of expressing the results of repeated dosing may be
used to compare the tendency of different compounds to have cumulative
effects without reference to their absolute toxicities. The chronicity
factor is defined as the single dose LD,.- in mg/kg divided by the 90-dose
LDc0 in mg/kg/day. The 90-dose oral $>Kn of mirex was found to be 6
mg7Kg/day which yields a chronicity factor of 60.8 (Mirex Advisory
Committee, 1972). This chronicity factor is by far the highest observed
for any pesticide to date. Comparable chronicity factors for DDT and
dieldrin are less than 5.6 and 12.8, respectively. Thus, mirex is highly
cumulative in effect; and like many other chlorinated hydrocarbons, it is
probably metabolized or excreted very slowly (Gaines and Kimbrough, 1970).
5.3.4.2.3 Metabolism—Ivie, et^al., (1974b) studied accumulation,
tissue distribution, and excretion of C-mirex in rats during extended
dietary exposure. Dosages administered to the treated rats were 0.3. 3-0,
and 30.0 ppm of mirex mixed into commercial rat meal. Uptake and
retention of radiocarbon in fat occurred rapidly after ingest ion of the
treated food. As shown in Table 5.11, a steady pattern of accumulation is
seen in the organs. In rats maintained on the mirex diet for 16 months,
mirex concentrations in the fat were approxiately 120-fold higher than
corresponding dietary intake levels. No plateau of residue accumulation
was observed in any tissue during the feeding period. Remarkably, the
106
-------
TABLE 5.11.
RADIOACTIVE RESIDUES IN THE TISSUES OF RATS
FED 30 PPM OF MIREX IN THE DIETa
Ppm of mlrex equivalents
Subcutaneous
Time
7
14
1
6
12
15
7
14
1
3
6
12
days
days
month
months
months
months
days
days
month
months
months
months
Brain
5.5
6.6
8.6
18.1
23.9
36.9
15.7
14.2
12.6
11.0
10.3
9.9
Muscle
5.
50.
6.
9.
26.
49.
8.
8.
7.
6.
6.
6.
5
0
4
1
5
5
Rats
6
6
4
6
4
3
Liver
15.7
32.0
38.9
63.4
98.9
158.0
Removed
61.2
58.6
55.5
42.8
32.8
25.2
Kidney
Rats on
9.6
11.1
12.7
22.1
34.3
52.1
Skin
Tissue0
Hair
Fatd
Treatment
25.7
40.9
82.4
229.6
374.5
421.6
from Treatment
18.0
16.9
14.9
12.5
10.8
10.1
231.3
220.9
216.7
176.2
184.4
133.6
33.
138.
170.
211.
278.
321.
4
7
5
3
7
3
6.1
9.7
5.4
11.8
22.6
25.2
81
—
332
2047
2808
3730e
after 6 Months
204.
189.
198.
40.
67.
55.
6
0
2
7
2
7
6.7
7.3
6.5
5.3
5.4
4.9
1980
1907
1670
1490
1440
1340
a
Source: Ivie, et al (1974). Reprinted, with permission, from J. Ag and Food
Chemistry, (c) American Chemical Society (1974).
Ratios of the levels of residues in the tissues to those in the diet were the
same for all three feeding levels, 0.3, 3.0, and 30.0 ppm.
Q
Connective tissue between epidermis and muscle.
Females only.
Based on 16 months.
-------
ratios of the levels of residues in tissues to those in the diet were
essentially identical for all three feeding groups. For example, the 3.0
ppm group accumulated ten times the residues of the 0.3 ppm group and
one-tenth that of the 30 ppm feeding group. Radiocarbon dissipated very
slowly from the tissues following cessation of the treated diet; one-half
or less of the residues had been eliminated 10 months after treatment
stopped. A majority of the total mirex consumed was retained by the body
tissues. Radioassay of feces and urine throughout the study indicated
that approximately 25 percent of the total ingested radiocarbon was
eliminated by the fecal route; excretion via the urine was negligible. GC
and TLC of radiocarbon residues from feces and kidney samples revealed
only a single compound which corresponded in chromatographic behavior to
mirex. Analysis by mass spectrometry confirmed that the residue was
indeed the unmetabolized parent compound. Hundreds of analyses over the
16-month period of this investigation showed no evidence of mirex
metabolism. In addition, the levels of mirex residues accumulated in
tissues were considerably higher than those reported for other lipophilic
pesticides. Furthermore, following cessation of treatment, body burdens
of mirex in rats dissipated at a much slower rate than those of either
DDT or dieldrin. In spite of the relatively poor absorption of mirex from
the gut, the extraordinary long half-life in the tissues indicates the
potential for accumulation of high levels of mirex even at low doses.
Also, since mirex is not degraded by either plants or animals,
accumulated mirex can be expected to be recycled upon the death of the
organism. Ivie, et al., (1974b) concluded from these and earlier studies
that mirex is probably the most stable organic pesticide known.
A study by Mehendale, et al., (1972) was undertaken to determine the
fate of a single dose of mirex such as might be encountered by an animal
in the environment. Their report identifies the routes and rates of
excretion and the amounts and locations of storage in. the bodies of a
group of male rats fed a single dose of 6.0 mg/kg of C-mirex. Findings
were (1) the primary route of mirex excretion is the feces; (2) 55
percent of the administered dose of mirex was excreted in the first 48
hours after administration, most probably representing that portion of
the dose which passed unabsorbed through the gut. (3) total excretion
levels off rapidly after 48 hours and very little is excreted in the
urine, suggesting that once absorbed mirex is readily stored and only
slowly excreted. Excretion kinetics appear to be biphasic; the initial
"fast" phase lasts about 38 hours and the slow phase (second half-life)
is estimated to be in excess of 100 days. (4) Urinary excretion accounted
for less than 1 percent of excretion and analysis did not reveal any
radioactive compound other than mirex; (5) within the body, tissues and
organs retained approxmately 34 percent of the total dose at necropsy 7
days after administration of the dose. Out of this 34.2 percent retained,
the tissue distribution of the stored mirex was approximately as follows:
27-8 percent in fat, 3.2 percent in muscle, 1.75 percent in liver, 0.76
percent in kidney, ..and 0.23 percent in the intestines. Table 5.12 shows
the distribution of C-mirex in the rats. No radioactive compound other
than mirex was detected.
108
-------
TABLE 5.12. DISTRIBUTION OF 14C-MIREX
ADMINISTERED ORALLY TO RATS
a,b
Percent of Total
Dose Retainedc
Tissues or Organs
Fat
Liver
Small intestine
Muscle
Large intestine
Stomach
Heart
Kidney
Brain
Testes
Lung
Subtotal
per g of
Tissue0
1.54
0.15
0.10
0.04
0.10
0.05
0.05
0.25
0.04
0.06
0.07
Total
27.8
1.75
0.76
3.20
0.23
0.06
0.03
0.09
0.07
0.12
0.08
34.19
Excretion
Feces
Urine
Total recovery
58.5
0.69
93.38
Source: Mehendale, et al. (1972). Reprinted,
with permission, from Bull. Environmental Con-
tamination and Toxicology, (c) Springer-Verlag
New York Inc. (1972).
6.0 mg/kg mirex
intubation.
°Wet weight basis.
administered by oral
109
-------
A similar investigation by Gibson, et al., (1972) examined the fate
of mirex along with a major photoproduct in rats. In general, the results
of this investigation were quite similar to those of the study by
hendale, et al., (1972) mentioned above. Rats receiving single doses of
C-mirex eliminated about 18 percent of the administered radiocarbon
during a 7-day period. Eighty-five percent of this amount was eliminated
via the feces within 48 hours after administration. Only trace amounts of
radioactivity were detected in the urine. Essentially all of the excreted
radioactivity was unmetabolized mirex. Intestinal absorption of mirex was
slightly depressed by the presence of an existing body burden. Mirex
demonstrated an affinity for lipids; and once absorbed into fatty tissue,
the residue levels remained essentially unchanged for periods up to 28
days. TLC and GC analyses revealed that the radiocarbon residues in fat
consisted entirely of unaltered mirex. The photoproduct was also highly
lipophilic in nature and chromatographic analysis revealed that the
photoproduct radiocarbon stored in fat 7 days posttreatment was also
entirely unmetabolized.
Two recent articles describe mirex kinetics in the rhesus monkey and
develop a pharmacokinetic model of mirex disposition in the body (Wiener,
et al., 1976; Pittman, et al., 1976). The first study administered
C-mirex to three female rhesus monkeys in a single dose equivalent to
about 1 mg/kg either intravenously (two animals) or orally (one animal).
Blood plasma, urine^feces, and tissue samples were obtained periodically
and analyzed for C-mirex. Tissues were obtained at autopsy at 23, 106,
and 388 days after dosing for the three monkeys, respectively. Absorption
patterns varied according to the method of administration, with the
intravenous doses producing initial high levels which declined rapidly
over the next few hours. Oral dosage produced measurable C-mirex in the
plasma 2 hours after administration, reaching a maximum at 5 hours.
Thereafter, the rate of decline in plasma radioactivity was similar in
all three monkeys; and within 24 hours, plasma radioactivity was less
than 5 percent of the earliest value measured. Plasma C-mirex continued
to decline at a much slower rate and remained in measurable quantities
during the study. Urinary excretion declined rapidly over the first week
with total urinary excretion over this period amounting to less than 0.6
percent of the dose. Figures 5.3 and 5.4 show plasma and urinary levels
as a function of time since dosage. In all tissues analyzed, C-mirex
was detected. Fat had by far the highest concentration, followed by
adrenal gland, peripheral nerves, thyroid gland and skin. Tables 5.13 and
5.14 show tissue content and percent of administered mirex found in
tissues at autopsy. Excretion of C-mirex in feces was initially rapid;
about 25 percent of the dose appeared in the feces of the orally-dosed
monkey within 48 hours. Daily excretion of mirex in the feces of
intravenously-dosed monkeys closely paralleled mirex levels in plasma.
Cumulative fecal excretion of C-mirex over a period of 1 year was less
than 7 percent of the dose. No metabolites of mirex were isolated after 2
days in fecal samples; however, extracts of fecal samples after 14 days
or more showed small amounts (approximately 3 percent of the total C-
content) of an unidentified compound more polar than mirex. The authors
suggested the possibility that this unidentified substance found in the
110
-------
FIGURE 5.3.
1 .
1
X .1
!» O5
*
.005
-001
TIME AFTER ADMINISTRATION OF MIREX
(doys)
O. monkey no. I (doited iv): O. monkey no. 2 (doted
iv); •. monkey no. 3 (dosed po).
Plasma levels of mlrex after administration of
to female rhesus monkeys.
14
C-mirex
Source: Wiener, et al. (1976). Reprinted, with permission,
from Drug Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
FIGURE 5.4.
O. monkey no. I (d.)si-d iv); O. monkey no. 2 (dosed
iru3 Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
Ill
-------
TABLE 3.13. TISSUE CONTENT OF RADIOACTIVITY AS NIRBX IN FEMALE RHESUS MONKEYS
AFTER ADMINISTRATION OF A SINGLE DOSE OF 1*OMIREX a
Minx Equivalent!,
na/a of Tiaaue
Ftt
Bone narrow (yellow)
Brown
Llpoma of brow
Meaenterio
Omental
Peri-renal
Subcutaneous
Bndocrina Syataa
Adrenal
Ovariea
Corpua luteum
Interatitial gland
Pancreea
Pituitary
Thyroid
Nervoua Syatem
Cereb run- frontal lobea
Cerebellum
Medulla
Meningea
Peripheral nerve
Sciatic
Brachial plexua
Pona
Spinal cord
Thalaaua
No. 3,
23
Daya
(Oral)
1200
2570
2120
1680
341
302
137
35
93
102
83
134
18
268
102
No. 1,
106
Daya
(iv)
4960
6930
3760
5880
2630
262
112
110
865
81
79
110
874
130
143
85
No. 2,
388
Daya
(iv)
2140
1250
2070
2950
1860
2630
651
100
66
139
13
168
27
31
47
11
332
330
35
Mirex Equivalents,
na/a of Tiaau«
No. 3,
Other .
Bil.b
Plannrn
Aorta
Bladder
Diaphragm
Eyeball
Fallopian tubea
Hair
Heart ( van tr idea)
Inteatine
Small
Large
Kidney
Liver
Lung
Nuacle, akeletal
Parotid
Skin
Spleen
Stomach
Tongue
Uterua
Myoma trium
Bndometrlum (proliferative)
Vena cave
23
Daya
(Oral)
40
23
36
238
183
11
61
81
73
100
743
63
341
36
39
64
32
61
16
181
No > 1 * No . 2 1
106
Daya
(Iv)
120
19
156
61
103
349
61
363
61
34
1017
34
103
20
*Sourc«i Wiener, et al. (1976). Reprinted, with peniaalon, fro* Drug Hataboliam and Diapoeitlon. (c)
Society for Pharmacology and Exparlaental Therapeutioa (1976).
HgSml.
388
Daya
(Iv)
12
7
61
28
30
20
38
47
29
105
43
132
43
10
33
251
14
28
38
7
13
161
American
-------
TABLE 5.14.
PERCEBT OP ADMIMISTERED MIREX FOUHD IH VARIOUS
TISSUES AT AUTOPSY OF FEMALE RHESUS HOTKEYS3
Percentage of
Tissue
b
Fat
Skinc
Skeletal Muscle
Large Intestine
Liver
Brain
Small Intestine
Stomach
Heart
Lungs
Pancreas
Kidney
Adrenal
All other tissues
Total measured in
Total measured in
Ho. 3,
23
Days
55.3
2.0
1.01
0.92
0.22
0.14
0.049
0.035
0.026
0.039
0.025
0.0055
0
analyzed 0 . 016
urine 0.64
feces 26.53
87.0
Ho. 1,
106
Days
87.4
10
1.7
0.36
0.51
0.13
0.11
0.051
0.017
0.027
0.011
0.017
0.033
0.016
0.37
4.69
105.4
Dose
Ho. 2,
388
Days
85.7
3.7
0.60
0.21
0.42
0.05
0.06
0.019
0.022
0.032
0.015
0.012
0.012
0.0097
0.18
6.91
98.0
source: Wiener, et al. (1976). Reprinted, with per-
mission, from Drug Metabolism and Disposition, (c)
American Society for Pharmacology and Experimental
Therapeutics (1976).
The total fat on monkey Ho. 1 was estimated to be
15 percent of body weight. Monkeys Ho. 2 and Ho. 3 were
obese and the estimate was 25,percent of body weight.
cSkin was estimated to be 10 percent of body weight.
Skeletal muscle was estimated to be 50 percent of body
weight.
Hone of the remaining tissues analysed contained
more than 0.0089 percent of the dose.
113
-------
feces might have been a spontaneous decomposition product, resulting from
prolonged exposure to fluorescent light in the cages (photodecomposition)
rather than bacterial decomposition in the gut of the monkey, since
collection and analysis were delayed.
Ill
In a related study, Pittman, et al., (1976) measured C-mirex in
plasma, urine and feces at intervals after dosing and in tissues at
autopsy. Graphical analysis of plots of the logarithm of plasma
concentration vs time provided estimates of the values of the first-order
rate constants needed for the pharmacokinetic models. These parameter
values are shown in Table 5.15. A computer program, FITKIN, was used to
solve the differential equations for each model and to adjust these
numerical solutions to obtain a normalized, least-squares fit. A
mammillary, four-compartment, open system model was selected from among
the alternatives since this model allowed for urinary excretion of mirex
from a "central" compartment and for fecal excretion of mirex from a
"fast" tissue compartment. This model yielded theoretical data which were
in good agreement with the observed values. A schematic diagram of the
model is shown in Figure 5.5.
Figure 5.6 shows the plasma level vs time for monkeys 1 and 2 as a
function of days after administration. For the first monkey, the last few
plasma concentration data points were omitted because of an accidental
failure to feed this monkey for a few days, as indicated by the arrow in
Figure 5.6. Apparently the starvation period resulted in fairly rapid
release of depot mirex into the central compartment.
Figure 5.7 shows the cumulative fecal and urinary excretion of mirex
as a function of days after administration. At the time each monkey was
killed, the predicted dose remaining in the fourth compartment (the "very
slow" tissue compartment) was 87 percent for Monkey No. 1 and 84 percent
for Monkey No. 2. These values are in good agreement with the percentage
of the dose estimated to be present in the fat at autopsy, 86 and 87
percent, respectively. Principal findings of the study were: (1) The fit
of the data for fecal and urinary excretion with the model was
acceptable, indicating that mirex distribution is not influenced by the
route of administration, save that the differences in initial absorption
must be accounted for. (2) The maximum concentration of mirex in the
"very slow" compartment did not occur until 3 months to a year after a
single dose. (3) Even though excretion of mirex in urine and feces was
continuous, the projection estimated a decrease in the body burden of
only 1-2 percent of the amount present at the end of the first year over
the next 4 years, as shown in Figure 5.8. The values shown were
calculated using computer-optimized parameters. (4) The program MODEL was
used to simulate the disposition of mirex during hypothetical dietary
regimens of 0.25 and 1.0 mg/kg/day for 10 years. For the first 3-6 months
of the simulation, the rate at which the projected quantity of mirex in
any compartment increased varied noticeably, the rate of change
decreasing in the central compartmment and increasing in the peripheral
compartments. After 6 months, the rate of increase in all compartments
appeared to be linear; plateau levels were not reached in 10 years.
114
-------
TABLE 5.15. PARAMETERS FOR MIREX MODEL IN MONKEYS'
Parameter
k!2
k21
k!3
k31
k!4
k41
kio
k30
Vcc
Values in Monkey No.
1
0.4582
0.05607
0.7935
0.6372
0.3451
0.0008168
0.003216
0.01136
3.798
2
0.1938
0.02530
1.013
0.3157
0.1881
0.002539
0.002489
0.002342
7.458
3
0.4508
0.0608
0.9909
0.4817
0.2890
0.0008055
0.002027
0.009340
6.444
Source: Pitmann, et al, (1976). Reprinted, with
permission, from Drug Metabolism and Disposition.
(c) American Society for Pharmacology and Experi-
mental Therapeutics (1976).
Values were obtained by least-squares fitting
to a four-compartment, open system, mammil-
lary model. Rate constants are days"!.
'Vc is in liters.
Vc is
the volume of distri-
bution of the central compartment, a constant
necessary to convert the plasma concentrations
of mirex to quantities of mirex in the central
compartment.
correspond
to parameters in
Table 5.15.
FIGURE 5.5.
Scheme for four compartment open-
system mammilary models
Source: Pittman, et al. (1976). Reprinted, with permission,
from Drug Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
115
-------
J. J-.,. I ., .l._L J
2O 40 60 SO 1OO 12O
DAYS AFTER ADMINISTRATION
(a) Monkey No. 1
1.0h
0.1
0.5
.01
.005
I I I
0 60 120 ISO 24O 300
DAYS AFTER ADMINISTRATION
(b) Monkey No. 2
o, Experimental values used in computer fitting; o, experimental
values not used in computer fitting. The line is drawn from values
derived from computer fit of the four-compartment model.
FIGURE 5.6.
Plasma levels of mirex vs time in monkeys after iv
injection of ^C-mirex.
Source: Pittman, et al. (1976). Reprinted, with permission,
from Drug Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
116
-------
2O 40 60 80 100
DAYS AFTER ADMINISTRATION
1
120
(a) Monkey NO
A, Experimental urinary excretion
data; o, experimental fecal ex-
cretion data. The lines are drawn
from values derived from computer
fit of the four-compartment model
for urinary excretion (---),
and for fecal excretion ( ).
...I -I. I .!_.
240 300
60 120 180
DAYS AFTER ADMINISTRATION
(b) Monkey NO. 2
b A, Experimental urinary excretion
data; o. experimental fecal excretion
data used in computer fitting, o,
experimental fecal excretion data not
used in computer fitting. The lines
are drawn for values derived from
computer fit of the four-compartment
model for urinary excretion (---),
and for fecal excretion ( ).
FIGURE 5.7.
Cumulative fecal and urinary excretion of mirex vs time in
monkeys after iv injection of l^C-mirex.
Source: Pittman, et al. (1976). Reprinted, with permission,
from Drug Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
117
-------
3000
VERY SUW COMPttRTMinr 14)
FECESI6).
"012345
YEARS AFTER ADMINISTRATION
FIGURE 5.8.
Calculated amount of mirex in various compartments vs time
in monkey No. 2 after a single iv injection of l^C mirex.
Source: Pittman, et al. (1976). Reorinted, with oermi.ssion,
from Drug Metabolism and Disposition, (c) American Society
for Pharmacology and Experimental Therapeutics (1976).
118
-------
There is very little doubt that the "very slow" compartment
postulated in the model corresponds directly to adipose tissue and other
especially lipid-rich and poorly perfused tissues. The "slow" compartment
may correspond to moderately perfused bulk tissue such as muscle. The
identity of the "fast" compartment from which mirex is excreted into the
feces is presently unclear; however, the large^intestine is a likely
candidate in view of the high concentration of C-mirex in this tissue.
The volume of mirex in the "central compartment" probably includes the
plasma and body water and perhaps other tissues which might accumulate
mirex preferentially to the plasma.
Very recently, Smrek et al., (1977) reported a study of the
pharmacokinetics of mirex in goats. Their experiment involved oral
administration of mirex to male and female goats at various dosages and
exposure regimens. Included in the study were several female goats who
were observed during pregnancy and lacation. Plasma, milk and adipose
tissues of the animals were analyzed for mirex at intervals.
During the course of the study (61 weeks) no obvious signs of
toxicity were noted at the mirex dosage of 1 mg/kg body weight/day. The
authors found that the various biological compartments (plasma, millk,
adipose tissue) seem to be independent of one another. While plasma
levels stabilize, adipose tissue levels increase and colostrum levels
were higher than milk levels. Milk levels fluctuated, but no particular
trend was discerned. The plasma levels, having stabilized, did increase
in response to higher dosages, so that apparently the capacity of the
plasma to transport mirex is not a limiting factor in the plasma level at
dosages of 1-10 mg/kg body wt/day. One potentially important finding is
that since plasma levels do not appear to increase in proportion to the
concentration in adipose tissue, the determination of plasma levels in
cases of chronic exposure is of little value for predicting adipose
tissue levels. Furthermore, neither pregnancy nor lactation while
maintaining dosage caused any decline in adipose tissue levels. There
were some sex-specific differences seen: adipose tissue levels of mirex
were lower in females than males. Mirex concentations in adipose tissues
of males also showed greater fluctuation. Steady mirex concentrations
were not reached in the course of the study (approximately 14 months)
whereas the plasma levels became stationary after about 5 months.
5.3.4.2.4 Enzymatic and cellular effects—Induction of hepatic
microsomal enzymes is a general characteristic of chlorinated hydrocarbon
insecticides, including mirex and Kepone. Baker, et al., (1972)
demonstrated this effect in both rats and mice exposed to various
concentrations of mirex via intraperitoneal injection or through diet. In
the injection experiments, mirex was administered intraperitoneally at
dose levels of 5, 10, 25, and 100 mg/kg 72, 48, and 24 hours before the
animals were killed. In the feeding experiments, mirex was added to the
pelleted feed in concentrations from 1 to 250 ppm for 14 days.
119
-------
Mirex treatment of both mice and rats elicited a significant
increase in hepatic cytochrome P-450 levels and relative liver weight.
The mice and rats treated with 25 mg/kg exhibited cytochrome P-450 levels
of 2.67 and 1.55 times that of the control, respectively. Although the
liver-to-body weight ratio for rats was not affected at this dosage
level, mice treated at 25 mg/kg had liver-to-body weight ratios 1.26
times that of the control. A dosage of 100 mg/kg in rats produced a
significant change in relative liver weight and also an increase in
cytochrome P-450 levels to 2.5 times that of the controls. After 14 days,
dietary dosages of mirex over 1 ppm caused induction of cytochrome P-450.
At the higher dosage levels, the induction effect was much more
pronounced. The cytochrome P-450 level was approximately twice the
control levels at the mirex dosages of 1 to 25 ppm and 6 times the
control levels at dosages of 100 to 250 ppm. In the rats tested, dietary
mirex dosages of 1 to 250 ppm for 14 days resulted in increases in smooth
endoplasmic reticulum. This effect was increasingly apparent as the dose
level increased. The physiologic significance of this induction has not
been adequately evaluated, however, interactions between induction and
various drug or steroid metabolisms have been suggested.
In a study by Abston and Yarbrough (1976), adult male and female
rats fed dietary mirex concentrations of 10, 20, 30, 40, and 50 ppm for 4
weeks exhibited significant decreases in liver levels of lactic acid
dehydrogenase (LDH), malic dehydrogenase (MDH), sorbitol dehydrogenase
(SDH), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic
transaminase (GPT) as compared to controls. These enzymes are associated
with cellular metabolic activity. LDH is present in most animal tissues
and is involved in interconversion of pyruvic acid to lactic acid,
serving as a pivotal enzyme between the glycolytic pathway and the
tricarboxylic acid cycle. MDH is a tricarboxylic acid enzyme involved in
the conversion of malic acid to oxaloacetic acid. GOT and GPT are
transaminases involved in the interconversion of metabolic intermediates
relative to energy metabolism and gluconeogenesis. SDH is instrumental in
conversion of glucose to fructose; elevated serum SDH levels are
considered to be an indicator of liver cell damage. The observed losses
of LDH, GPT, GOT and MDH were from the cytoplasmic portion of the
hepatocytes rather than from the mitochrondrial portions. At equivalent
mirex dosages, decreases in enzyme levels were consistently less in
female rats as compared with males. The ratio of liver weight to body
weight generally increased during the course of the experiment although
the increases varied according to dosage level, sex, and elapsed time.
The authors suggest that the increases in liver weights following mirex
(and other organochlorine insecticide) exposure may represent an adaptive
hypertrophy and not a toxic expression of the insecticide itself.
Typically, serum enzyme levels indicate compensation reactions taking
place at the organ level, from cell damage to death. The decreases in
enzyme levels were both dose and time dependent. The authors believe that
in an environment in which organochlorine insecticide exposure occurs
continually at a low dose, these adaptive responses may become
contributory factors in a population's ability to successfully meet
environmental stress.
120
-------
Because the LD of mirex and Kepone in many species is very high,
it has been commonly Relieved that accumulation levels represented no
hazard to species which might be naturally exposed, since these
accumulated concentrations were well below typical lethal doses. However
Hendrickson and Bowden (1975a) have shown that LDH (crystalline from
rabbit muscle) is competitively inhibited by mirex and Kepone at levels
as low as 10 ppm during in vitro determinations. Both mirex and Kepone
were competitive inhibitors to pyruvate; the apparent inhibition constant
(K ) was 0.02 mM for both pesticides. Figure 5.9 shows Dixon plots of the
effect of mirex and Kepone on LDH activity.
The Dixon plot is a commonly used graphical method for determination
of the apparent inhibition constant (K.) in the presence of an inhibitor
(Dixon and Webb, 1964). Basically, Hhe method involves plotting the
velocity of the reaction as determined for a series of inhibitor
concentrations while keeping the substrate concentration constant.
Hendrickson and Bowden (1975a) assayed LDH activity by following the rate
of conversion of pyruvate to lactate in the presence of NADH by the loss
of absorbance of NADH at 340 nm in a Beckman DB spectrophotometer
1135
MIREX x l02,mM
•i I 3
KEPONE x IOz.mM
Figure 5.9 Dixon plots of effect of mirex and
Kepone on LDH activity.
Source: Hendrickson and Bowden (1975).
Reprinted, with permission from J.
Agricultural and Food Chemistry.
i < in Figure 5.9, the concentration of pesticide, in
A, MSfl£10,^ed agalnSt 1/Vi where Vi is the initial velocitV in
NADH (the reduced fom °f c°enzyme I) consumed per minute.
Cr«nCen 1?tai°ns Of Pestici
-------
A straight line was obtained by plotting pesticide concentration vs
1/V.. Lines A and B represent the effects of various concentrations of
mirex or Kepone added to cuvettes containing pyruvate at either of two
concentrations (A or B), while keeping the concentration of NADH, ethanol
and phosphate buffer constant. The intersection of Lines A and B (each
representing a series of inhibitor concentrations having a constant
substrate concentration) gives the inhibition constant.
The observed inhibition occurred at test levels well below usual
lethal doses and was comparable, in fact, to accumulation concentrations.
LDH is common to many species which participate in man's food chain.
Because LDH occupies a key position in the anaerobic glycolytic pathway
of skeletal muscle, impairment of the function of this enzyme in energy
production could result in possible harmful effect on muscle function.
Using LDH as a model system, Hendrickson and Bowden (1975b) proposed
a mechanism for the in vitro inhibition of NADH linked dehydrogenase by
halogenated hydrocarbon pesticides, including mirex. This mechanism
includes (1) the association of NADH and mirex, and (2) binding of mirex
with the adenosine-binding pocket of LDH (because of the hydrophobia
character and structural similarity of mirex in comparison with other
competitive inhibitors of dehydrogenases). The mechanism is consistent
with the inhibition patterns obtained by the investigators in their
studies of time-dependent association of NADH and pesticide and the
postulation that mirex binds at the adenosine-binding pocket of
dehydrogenases. The theory not only includes the inhibition of LDH by
polychlorinated pesticides, but also the inhibition of other NAD-linked
dehydrogenases and other enzymes which utilize adenosine-containing
coenzymes: FAD(H2>, NADP(Hp), coenzyme A, ATP, and ADP. A scheme for the
actual in vivo mechanisms by which polychlorinated hydrocarbons exert
their lethal neurophysiological effects is proposed. This mechanism
includes the disruption of nerve membrane-bound ATPases (which maintain
intracellular/extracellular ion ratios) by pesticide binding at the
adenosine-binding pocket of the ATPase.
A common responses of liver cells to toxic stress is the
accumulation of lipids, usually in the form of triglycerides. Kendall
(1974a) reported a study in which a lipophilic stain, Sudan black, was
utilized to visualize fat inclusions in the livers of rats. The single
LD__ mirex dosage of 365 mg/kg, when administered intraperitoneally,
produced several distinctive histologic alterations in the liver after 12
days. These changes included apparent depletion of stainable glycogen,
hepatocyte enlargement, periportal liposis associated with central
necrosis and infrequent foci of necrosis on the surface. When the LDc0
dosage was fed ad libitum all of the above types of injuries except
surface lesions occurred. Mirex caused lipid accumulation in an extremely
distinctive histologic pattern of periportal liposis. No sudanophilic
positive material was observed in liver tissue of unexposed controls.
Kendall (1974b) is currently investigating the cirrhogenic potential of
mirex in light of these findings.
122
-------
Mirex has been shown to increase liver weight and to produce a
proliferation of smooth endoplasmic reticulum and an incease in hepatic
mixed function oxidases in the rat Baker, et al., (1972) Abston and
Yarbrough, (1976), Gaines and Kimbrough, (1970) . An article by Byard, et
al., (1975) extended these findings to mice and suggested that a large
component of the liver growth produced by mirex in the mouse is due to a
stimulation of DNA synthesis which leads to overall cellular growth. An
early, controlled response of DNA to the growth stimulus resulted in
overall cellular growth of about 130 to 150 percent of control values.
Beyond this level, and as a result of further cellular changes produced
by mirex or aging, a more rapid increase in DNA was initiated which was
associated with the appearance of nodules. Byard, et al., (1975) offer an
interesting hypothesis to explain the action of lipophilic chemicals
(such as mirex and Kepone) in proliferating the smooth endoplasmic
reticulum. According to the hypothesis, these chemicals mimic a
lipophilic substance in the body which normally controls the synthesis of
components of the smooth endoplasmic reticulum. For example, steroid
hormones have been shown to bind to specific receptor proteins in the
nucleus, and stimulate RNA synthesis. Similar mechanisms have been
proposed for chemical inducers of smooth endoplasmic reticulum
proliferation. The fact that mirex binds to soluble cytoplasmic proteins
in the liver is consistent with this hypothesis.
5.3-4.2.5 Reproductive effects—Laboratory studies have repeatedly
demonstrated that mirex and Kepone are capable of producing similar
adverse reproductive effects in numerous species. Both pesticides have
been associated with the following effects:
(1) Reductions in fertility and litter size
(2) Increased rate of fetal visceral anomalies
(3) Elevated pesticide levels in tissue of fetuses and offspring
as a result of placenta! transfer and/or lactogenic exposure
(4) Decreases in birth weight and survival rate of young.
In addition, lactogenic exposure to mirex has been associated with the
development of cataracts in the young.
Gaines and Kimbrough (1970) fed mirex at dosages of 5 and 25 ppm to
Sherman rats for 45 and 102 days. Reproductive activity of male rats (fed
25 ppm) and females (fed 5 ppm) bred to untreated rats was comparable
with that of controls. Females fed 25 ppm mirex for 45 days and then bred
to non treated males had litters significantly smaller than those of
controls. The survival rate to weaning was significantly reduced and 33
percent of the offspring developed cataracts. Compared with controls,
females bred after 102 days' exposure to mirex had fewer litters, the
survival rate of the offspring was significantly lower (P 0.05) and 46.2
percent of the offspring developed cataracts. No cataracts were observed
in offspring of control rats nor in the-parent stock fed mirex.
Gibson, et al., (1972) also reported that for Sherman rats fed diets
containing 25 ppm of mirex for as little as 45 days fewer offspring were
123
-------
born alive, fewer offspring survived to weaning, and many pups developed
cataracts. Analyses of milk and fetuses showed excretion of mirex in the
milk and passage through the placental barrier. Another study by Ware and
Good (1967) investigated the reproductive effects of mirex on two strains
of mice. In all instances, mirex treatment resulted in a reduction of
litter size and number of offspring produced per day. The effect failed
to achieve statistical significance. In one strain of mice, mirex
produced a significant increase in parent mortality; however, in the
other strain this effect was not observed.
5.3.4.2.6 Placental and lactogenic transfer—In a study of
placental transfer of mirex in rats, Gaines and Kimbrough (1970) examined
fetuses taken from rats treated for 78 days. The fetuses contained
0.14-0.45 ppm of mirex; no mirex was detected in fetuses from controls.
Khera, et al., (1976) have also documented placental transfer of mirex.
Gaines and Kimbrough (1970) also provided evidence of excretion of mirex
in milk and the toxic effects of lactogenic exposure to suckling rats.
The survival rate to weaning of rats, transferred at birth from dams fed
non-treated diet to foster mothers also fed the non treated diet, was
95.8 percent; none developed cataracts. The survival rate of rats exposed
to mirex in utero only did not differ significantly from that of controls
and only 1.6 percent developed cataracts. When rats born to non-treated
mothers were exposed postpartum to mirex-treated foster mothers until
weaned, their survival rate was only 53-9 percent or 41.9 percent less
than that for controls; 37-5 percent developed cataracts. The low
survival rate of offspring of treated dams was caused chiefly by the high
mirex content in the mothers' milk. The mean mirex content of milk taken
from the stomachs of suckling rats was 11.3 ppm.
5.3.4.2.7 Teratogenic effects and dominant lethal study—A recent
investigation by Khera, et al., (1976) has demonstrated the teratogenic
potential of mirex in rats. Low doses of mirex (1.5 or 3.0 mg/kg given as
a single daily oral dose on days 6 to 15 of gestation) produced neither
adverse fetal effects nor symptoms of maternal toxicity. However, dosages
of 6.0 or 12.5 mg/kg administered according to the same protocol caused
maternal toxicity and increased fetal visceral anomalies. At the 12.5
mg/kg dose level, decreased fetal survival and reduced fetal weight also
occurred.
A dominant lethal study also reported by Khera, et al., (1976) did
not demonstrate significant differences in reproductive parameters
between male control rats and experimental groups of male rats fed 0,
1.5, 3.0 or 6.0 mg/kg daily for 10 days before mating. Mirex was detected
in the testes of the experimental group, however.
5.3.4.2.8 Carcinogenic and tumorigenic effects—Innes, et al.,
(1969) examined mirex as part of a large scale study designed to screen
selected pesticides and industrial compounds for tumorigenicity. Mirex
was tested by oral and subcutaneous routes of administration in two
hybrid strains of mice. Eighteen male and 18 female mice of each strain
were utilized for each test procedure. In the subcutaneous test, mirex
124
-------
was administered in a maximally tolerated single dose of 1000 mg/kg. In
the oral experiments, a dose of 10 mg/kg/day was given from the seventh
to the twenty-eighth day. The mice were then fed mirex at the level of 26
ppm in the diet for the duration of the experiments. All mice in both
experiments were sacrificed approximately 18 months after the beginning
of the experiment. The search for effects included an external
examination and a thorough examination of thoracic and abdominal
cavities, with histologic examination of major organ and all visible
lesions. Evaluation of tumorigenicity was based on magnitude of the
relative risk, comparing tumor incidence among the treated mice with that
of the controls. A separate analysis was performed for each of four tumor
groupings: hepatomas, pulmonary tumors, lymphomas and total mice with
tumors. Findings are summarized in Tables 5.16 and 5.17. Hepatic tumors
were the only type observed in the mirex-fed mice.
In the oral administration tests, all mice died prior to the
completion of the experiment at 18 months. Twenty-nine of 72 mice
developed hepatomas, compared to 14 of 338 control mice, a difference
significant at P 0.01. The authors stated that mirex induced a highly
significant (P 0.01) increase in liver hepatomas in both strains of mice
tested. Liver tumors were diagnosed as carcinomas. The classification
"hepatomas" in Tables 5.16 and 5.17 also includes metastasizing hepatic
cell tumors and should not be taken to imply that the tumors were benign.
The significance of this bioassay is strengthened by the fact that
seven known carcinogens, included in the study as positive controls, were
found clearly tumorigenic by this test protocol. Mirex by oral
administration was judged to have a relative risk of 0.945 by comparison
with an average of seven known carcinogens, meaning that in this bioassay
procedure mirex possesses approximately 95 percent of the carcinogenic
potency of the seven known carcinogens tested.
A second carcinogenesis bioassay of mirex was conducted using
Charles River Caesarian derived (CD) rats. Mirex was administered in the
feed to groups of 26 rats of each sex at levels of 50 and 100 ppm for 18
months (Ulland et al., 1973; Ulland et al., 1977). Untreated controls as
well as a group of positive controls treated with a known carcinogen
(2-AAF) were included for comparative purposes.
At the time of the initial evaluation (Ulland et al., 1973) it was
reported that mirex was not carcinogenic in rats, however subsequent
re-analysis of the data (Ulland et al., 1977) using newer guidelines on
the classification of liver tumors indicated that mirex appears to be
carcinogenic. The controversy surrounding the pathologic classification
of liver neoplasms was discussed in the December 29, 1976 issue of the
Federal Register.
The test animals showed a wide spectrum of neoplasms which, except
for liver lesions, showed little correlation with mirex dosage.
Therefore, the relationship between mirex exposure and the development of
these lesions could not be established.
125
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TABLE 5.16. RELATIVE RISK FOR DEVELOPMENT OF TUMORS AMONG MICE
TREATED WITH MIREX WHEN COMPARED WITH CONTROLS3
ON
Mice with
Mirex
t_
Strain0
X
Y
Sum
Mice with
pulmonary
hepatomas
M
4'37d
8'14d
5.74fl
F
_ _ d.e
Inf. ,'d
87.78°
107.39
Sum
7.33d1
18.12"
11.54
M
0
0
0
tumors
F
0
0
0
Sum
0
0
0
Mice with
lymphomas
M
0
0
0
F
0
0
0
Sum
0
0
00
Total mice
with tumors
M
1.67
2.37
1.95
F
9.35*
16.26"
12.20
Sum
3.53
5.85
4.46
Adapted from Innes, et al., (1969).
Strain X-(C57BL/0 x CaXI/AnDFj.: strain Y-(C57BL/6 x AKR)F],.
Increased tumor yield significant at 0.05 level.
Increased tumor yield significant at 0.01 level.
g
Inf.—relative risk calculated as infinite. This figure may result from the absence
of. tumors in the control group and is not necessarily significant.
-------
to
TABLE 5.17. TUMORS AMONG MICE RECEIVING MIREX*
Total
mice
necropsied
Strain
X
Y
M
18
15
F
16
16
Weeks at
necropsy
M
59
59
F
70
69
Mice with
hepatomas
M F
6 8
5 10
Mice with
pulmonary
tumors
M
0
0
F
0
0
Mice
with
lymphomas
M
0
0
F
0
0
Total
with
M
7
5
mice
tumors
F
8
10
lapted from Innes, et al., (1969).
-------
There was a high incidence of tumors, regardless of sex or dose, but
no statistically significant differences were noted except for tumors of
the liver (neoplastic nodules). One carcinoma was detected in the low
dose group, five in the high dose group and none in the control group.
The differences in this parameter between test animals and controls were
not significantly different from controls. Only the observation of 7
neoplastic nodules in the high dose (100 ppm) male rats was significant
at the 0.05 level. The authors did state, however, that this type of
neoplastic nodules has been shown to progress to hepatocellular carcinoma
in studies of other model carcinogens. In addition, the absence of
neoplastic nodules among animals unexposed to mirex and the fact that
this type of lesion is characteristic of early response to known
carcinogens is also suggestive of carcinogenic activity. According to the
authors, to call such nodules merely hyperplastic belies their neoplastic
nature and malignant potential.
5.3.4.3 Kepone—
5.3-4.3-1 Acute toxicity—In experimental animals (rats), the acute
oral and dermal LD_. of Kepone was 95 to 140 and 250 mg/kg, respectively.
In male rabbits, nEne acute dermal LD(-n was 345 to 475 mg/kg. DDT-like
tremors developed in these animals following a single dose, reaching a
peak intensity about the second day and persisting for about 1 week or
more (U.S. Environmental Protection Agency, 1975).
The acute oral LD__ of powdered technical Kepone (94.0 percent) when
administered as a 5 percent solution in corn oil to several species is
shown in Table 5.18. The characteristic effect of this compound was the
development of DDT-like tremors.
TABLE 5.18. ACUTE ORAL TOXICITY OF
KEPONE TO VARIOUS
MAMMALS3
Animal
Kepone dosage LD5Q
Male rats
Female rats
Male rabbits
Dogs
132.0 ± 8 mg/kg
126.0 ±12 mg/kg
71.0 ± 6 mg/kg
250.0 mg/kg
a Source: U.S. EPA (1975).
128
-------
Acute rat inhibition studies of 10 percent Kepone dust at levels of
2 and 10 times those that are likely to occur under agricultural
conditions produced no observable adverse effects. Concentrations chosen
were based upon observations made in actual use tests of the dust,
indicating a concentration of 1.6 mg Kepone active ingredient per cubic
meter of air inhaled. Two experimental groups were exposed tr> 10 percent
Kepone dust at levels of 3-7 mg/nr of air and 15.4 mg/nr . Ten daily
exposures of about 2 hours were conducted each, for a total of about 19
hours (U.S. Environmental Protection Agency, 1975).
The acute dermal LD,_0 in male rabbits of the powdered technical
Kepone administered as a 20 percent solution in corn oil was 410 + 65
mg/kg. Severe and persistent tremors developed with little or no skin
irritation. The LD5Q of the undiluted formulation was 435 + 11 mg/kg. The
formulation caused marked irritation and edema, followed by the
development of a hard scab which eventually sloughed off and revealed new
and apparently healthy skin.
5.3.4.3.2 Subacute and chronic toxicity—Huber (1965) investigated
the physiological effects of Kepone in the laboratory mouse. Subacute
mortality tests (tolerance tests) were conducted by feeding 0, 10, 30,
40, 60, 70, 80, and 100 ppm Kepone to juvenile and adult mice of both
sexes. Results showed that 80 ppm or higher was lethal to all adults
tested within 32 days, whereas 70 ppm was lethal to weaned juveniles
within 19 days. No mortality occurred in adults or juveniles fed 40 ppm
in tests extending up to 12 months. Food and water consumption of mice
fed 40 ppm or more of Kepone increased 20 to 40 percent with no increase
in body weight. Subacute lethal levels adversely affected the growth of
juveniles and caused weight loss in adults. Results are summarized in
Table 5.19. Constant tremor syndrome appeared within 4 weeks in all mice
fed 30 ppm or more; however, this terminated within 4 weeks following
withdrawal from the treated diet. Accumulation patterns are shown in
Table 5.20. The liver was the only organ which showed an increase in size
in all animals fed 30 ppm or more. At 40 ppm, the liver weight doubled in
60 to 90 days; it decreased in size when the treated diet was withdrawn.
Histologic findings at necropsy were focal necrosis, cellular
hypertrophy, hyperplasia and congestion, the degree of which depended on
length of treatment.
Kepone residues in the organs of mice showed maximum accumulation
within 5 months with no additional increase at a dietary level of 40 ppm
Kepone (Table 5-21). The liver was the major organ of accumulation while
the gonads, adrenals, uterus, spleen and heart showed little increase in
Kepone accumulation after the first 30 days of treatment. Further Kepone
accumulation took place mainly in the liver, brain, kidneys and body fat.
After withdrawal from the treated diet, Kepone residues decreased rapidly
from the various organs. As much as 56 percent of the accumulated Kepone
was lost by 24 days and up to 95 percent by 150 days (Table 5.22).
Effect of Kepone on male rats was demonstrated in a study in which
rats were given 9.6 mg/kg per rat per day for 20 days. Neurological
129
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TABLE 5.19. SUMMARY OF KEPONE MORTALITY STUDIES WITH THE
LABORATORY MOUSE3
Kepone in
Diet,
ppm
50
60
70
80
100
Age
Adults
Juveniles
Adults
Juveniles
Adults
Juveniles
Adults
Juveniles
Adults
Juveniles
Number
8
4
8
4
16
8
8
8
70
8
Initial
death,
days
70
107
75
17
5
5
5
6
2
Cumulative mortality
at indicated days of
treatment, percent
25
75
19
5
10
9
12
5
50
87
21
9
14
11
16
10
75
92
42
12
15
13
20
13
100
98
15
25
17
32
19
Source: Huber (1965). Reprinted, with permission, from Toxicology
and Applied Pharmacology, (c) Academic Press, Inc. (1965).
130
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TABLE 5.20. LIVER WEIGHT AS A PERCENTAGE OF BODY WEIGHT
IN KEPONE-FED AND CONTROL MICE3
Kepone in
Diet,
ppm
0
40
40
40
40
40
40
40
40
100
100
100
40
40
Days on
Kepone
diet
7- 14
21- 42
56- 60
90
120-150
180-210
240-270
500
7
14
21- 28
210
60
Days on
control
diet
0
0
0
0
0
0
0
0
0
0
0
120
120
Number
of mice
60
10
8
3
5
6
21
28
2
8
9
15
9
8
Percent
body
weight
6.0
7.8
9.2
12.0
11.8
12.6
13.5
13.3
15.0
10.2
12.4
13.5
8.8
7.1
a
Source :
Huber
(1965) . Reprd
jnted, with
permission,
from Toxicology and Applied Pharmacology, (c)
Academic Press, Inc. (1965).
131
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TABLE 5.21.
RESIDUES OF KEPONE IN MOUSE ORGANS AT A DIETARY
LEVEL OF 40 PPM3
Days on
40 ppm
Kepone
5
15
30
30
90
90
150
150
500
500,
100b
300D
Kepone
Liver
45
39
78
64
67
66
168
90
120
96
60
113
Brain
3
20
26
30
29
30
26
61
75
55
25
65
Kidney
7
30
27
32
27
39
74
37
88
35
25
49
Fat
13
27
25
33
29
34
81
49
84
29
41
22
» PPm
Muscle
5
20
15
15
16
23
19
26
11
10
8
Adrenals
67
25
15
37
45
86
72
20
25
Gonads
25
25
13
26
20
18
26
17
Source: Huber (1965). Reprinted, with permission, from
Toxicology and Applied Pharmacology, (c) Academic Press, Inc.
(1965).
Males, all others are females.
132
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TABLE 5.22. RESIDUES OF KEPONE IN MOUSE ORGANS AFTER WITH-
DRAWAL OF 40 PPM DIET3
Sexb
F
F
F
F
F
F
F
F
F
F
M
M
F
F
F
F
M
M
Days on
Kepone
diet
5
15
30
30
90
90
150
150
500
500
100
300
90
90
60
210
210
150
Days on
control
diet
0
0
0
0
0
0
0
0
0
0
0
0
14
24
150
150
150
240
Kepone, ug
Liver
67.5
77.0
140.0
96.0
160.0
138.7
520.0
335.0
418.0
403.2
189.0
450.0
125.0
59.4
1.4
0.8
9.4
1.2
Brain
1.2
7.2
13.5
10.7
11.5
11.0
8.3
25.5
30.0
23.5
10.5
26.0
5.4
5.4
0
0
0
0
Kidneys
1.8
8.4
6.7
7.7
6.0
8.5
22.8
13.4
29.0
9.0
11.7
24.0
1.0
6.5
0
0
0
0
Total
70.5
92.6
160.2
114.4
177.5
158.2
551.1
373.9
477.0
435.7
211.2
500.0
131.4
71.3
1.4
0.8
9.4
1.2
Source: Huber (1965). Reprinted, with permission, from
Toxicology and Applied Pharmacology, (c) Academic Press,
Inc. (1965).
M = male; F = female.
133
-------
effects (see Section 5.3.4.3.4) were also characteristics of Kepone-dosed
rats. Tremors appeared in all treated animals after the fifth dose.
Survivors of the 20-day study showed gradual subsiding of the tremors. No
lesions were found on histopathologic examination of selected organs
(U.S. Environmental Protection Agency, 1975). In a related long-term
study, six groups of rats (mixed sexes) were fed 5, 10, 25, 50, 80 ppm of
Kepone for 3 months. Food consumption, hematologic and urinary data were
collected. Organ weights and samples of organs and fat were also
collected for analyses of Kepone.
Tremors occurred in females but not in males after 3 months at the
dietary level of 25 ppm Kepone. Rats receiving 50 and 80 ppm showed
evidence of tremors as early as 2 weeks. Sugar in urine was negative and
trace quantities of protein were present. At 80 ppm, blood platelet
counts, serum calcium, prothrombin clotting time and (Factor V)
accelerator globulin were not significantly different from those of
controls. Survival was adversely affected at the 80 ppm level. Weight
depression became significant at dosages between 5 and 10 ppm in females
and between 10 and 25 ppm in males. Organ-to-body weight ratios were
significantly higher for liver in females at 5 ppm and males in the range
of 5 to 10 ppm. Kidney-to-body weight ratios were significantly elevated
in females at 10 ppm or greater and in males at 50 ppm. Similar ratios
for testes became significantly low at 50 ppm. Storage of Kepone in fat
generally increased with increased feeding levels of Kepone (U.S.
Environmental Protection Agency, 1975).
Details of the 12-month chronic rat study were the same as the
previous (3-month) study. After 7 months, female rats fed 10 ppm were
highly excitable but no muscle tremors were observed. Urine analyses for
sugar at 6, 9, and 12 months were negative at feeding levels of 5, 10,
and 25 ppm. Increased protein excretion was noted with increased dietary
levels of Kepone. Female growth was progressively reduced as dietary
Kepone increased above 5 to 10 ppm. Among males, there was no appreciable
effect on growth or survival at 5 to 10 ppm, but both sexes were affected
at 25 ppm. Oxygen consumption of both sexes at 25 ppm differed
significantly from controls, possibly resulting from an elevated
metabolic rate. Trends for organ to body weight ratios were similar to
those observed at 3 months. Lowered hematocrit and increased intake were
also noted.
Animals sacrificed at 12 months revealed liver enlargement due to
congestion, probably attributable to increased cardiac output and raised
metabolic rate which often accompany tremors. Necrosis was absent in the
nervous system nor were any unusual kidney lesions seen which could
account for the observed elevations in urinary protein.
In rats surviving between 1 and 2 years, two tissues, liver and
kidney, exhibited lesions that were subjected to special study and
interpretation. In the liver, the question concerned the possible
carcinomatous nature of lesions seen in six rats (three females on 10
ppm, one female on 25 ppm and two males on 25 ppm). Following independent
134
-------
review by four pathologists, this possibility remains an equivocal one.
The National Cancer Institute (NCI) is presently testing Kepone for
oarcinogenicity and a final report may be forthcoming in the near future.
Results of the preliminary report from NCI are discussed in Section
5.3.4.3.8.
A study in which groups of purebred beagle dogs were fed Kepone in
their diets for periods up to 127 weeks has been reported by the U.S.
Environmental Protection Agency (1975). Kepone levels in food were 0, 1,
5, and 25 ppm. During the first year, body weight gains were similar
among all groups, however, subsequent weight gains were significantly
lower in the dogs on the 25 ppm dosage. Food consumption data indicated
decreased efficiency of food utilization in the treated dogs as compared
with that of controls, possibly resulting from an increased metabolic
rate, an effect which has been demonstrated in rats. No effects on
hematocrit, hemoglobin, white cell counts, urinary sugar or protein, or
liver function were observed.
Statistically significant differences in organ-to-body weight ratios
were apparent for three organs at the 25 ppm dosage: the liver, the
kidneys and the heart. The increases in heart and kidney ratios may be
explained by the poor nutritional status of these animals (there was a
virtual absence of fat) rather than any specific physiologic response to
Kepone. The liver differences, on the other hand, were thought to reflect
a toxic effect specifically related to Kepone (rather than underweight).
Kepone fed to dairy cattle for 60 days at dietary levels of 0.25,
0.5, 1.0, and 5.0 ppm produced no apparent ill effects (Smith and Arant,
1967). Cows fed freely, gained weight, and produced a normal amont of
milk, and three cows dropped normal calves. Kepone was present in
measurable quantities in milk 1 week after the cows were placed on the
treated rations. There was a gradual increase in the amount of Kepone in
milk during the first few weeks and a leveling off in Kepone content at
the end of approximately 2 months. The highest residue reported in milk
was 0.44 ppm. Thirty-five days after removal from the treated rations,
cows formerly on the lowest ration (0.25 ppm) excreted less than 10 ppb
Kepone in their milk; similarly, those on the highest rate excreted
approximately 90 ppb. Eighty-three days following the cessation of Kepone
feeding, no measurable amount of Kepone was present in the milk of cows
fed the lowest rate and only traces were found in milk from cows fed the
highest rate.
5.3.4.3.3 Metabolism—Huber's (1965) residue studies, described in
the previous section, failed to reveal any Kepone metabolite in the
organs of mice fed mirex. This work provided the basis of the hypothesis,
since confirmed, that Kepone is very stable, a property which may enhance
rapid accumulation, especially in the liver and brain (Huber, 1965).
Recent radioactive tracer studies of Kelevan (ethyl
Kepone-5-levulinate) metabolism, showed that one metabolic product is
Kepone (U.S. Environmental Protection Agency, 1976a). Thirteen weeks
135
-------
after administration, the distribution of Kepone in rat tissues was as
follows: Liver kidney fat muscle. Information on blood
concentrations was not available. The reported data indicated that the
biological half-life of Kepone in rats is approximately 4 weeks. In
addition, the possible fat-plasma partition coefficient for Kepone is low
in comparison with other chlorinated hydrocarbon insecticides, making
more of the compound available to the liver for metabolism and to the
kidney for excretion. Since a high concentration of a component
calculated as C-labeled derived Kelevan was found in the colon
contents, intrahepatic recirculation of this compound and Kepone and/or
elimination is suggested.
5.3.4.3.4 Neurologic effects—The most characteristic neurological
effect of Kepone appears to be the induction of DDT-like tremors. The
severity of this effect (as with DDT and other chlorinated insecticides)
is dosage and time dependent. This response is common to most species
tested, including chickens, ducks, rabbits, mice and rats (and in man, as
evidenced by medical records of Life Science Products Company employees,
discussed in Section 6.4.2).
At sufficiently high dietary levels of Kepone, tremors have been
evoked in experimental animals, as shown below: (U.S. Environmental
Protection Agency, 1975).
Animal
Rats (fe-
male)
Dosage
Time to Tremor
25 ppm
3 months
Effect
Rat
Rats
9.6 ing/ kg
80 ppm
50 ppm
5 doses
2 weeks
3 weeks
Severe tremors
Tremors
Tremors
Tremors upon
stimulation
Mice and
rats
26-40 ppm
Tremors accompanied
by dermatologic
changes
In some of these tests, effects were seen to be reversible upon cessation
of feeding.
A report from the U.S. Environmental Protection Agency (1976a)
discusses the physiological mode of action of DDT and other chlorinated
hydrocarbon insecticides. Neurophysiological experiments have
demonstrated that these compounds exert their effect by prolonging the
flow of sodium (Na+) ions and interfering with the flow of potassium
136
-------
(K+) ions or by producing derangement in sodium and potassium conductance
during axonic conductance. Thus, the mechanics of muscle contracture is
affected by changes in the action potential.
5.3.4.3.5 Reproductive effects—Chronic doses of Kepone produce
effects on reproduction at levels ranging from 5 to 80 ppm. Huber (1965),
in his study described earlier, observed that the major adverse
physiologic effects resulting from ingestion of sublethal levels of
Kepone, exclusive of the liver pathology and tremor syndrome, involved
the reproductive processes. The female hormonal system was disturbed,
symptoms included: constant estrus, development of large follicles, and
absence of corpora lutea, probably resulting from prolonged stimulation
of FSH and estrogen but insufficient LH stimulation. Numbers of viable
offspring produced were reduced 23.9, 79.3, and 87.0 percent at 10, 30,
and 37-5 ppm, respectively. Matings between Kepone-fed females and
control males failed to produce any litters; however, control females did
produce litters when mated with Kepone-fed males. After resumption of the
untreated diet, reproduction resumed within 7 weeks. Initial litters were
smaller and had greater mortality than controls, indicating that
accumulated Kepone may exert a detrimental effect. Second litters were
larger with no greater mortality than control litters (Table 5.23).
A separate and independent mouse reproduction study (Good, et al.,
1965) showed that reproduction in mice was affected at all Kepone feeding
levels (10 ppm to 37.5 ppm) and that there was a decrease in size and
number of litters. Increased dose levels resulted in more severe effects
(U.S.Environmental Protection Agency, 1976a). In addition, a 3-month rat
study reported in Allied Chemical Corporation's Pesticide Tolerance
Petition revealed testicular atrophy in male rats at dosage levels of 25,
50, and 80 ppm (U.S. Environmental Protection Agency, 1976b).
Gastric intubation of 12 and 24 mg/kg/day for 4 consecutive days
after birth resulted in a reduction of litter viability in studies at the
Health Effects Research Laboratory (HERD at Research Triangle Park on
the effect of Kepone on reproduction in mice. (U.S. Environmental
Protection Agency, 1976a). In rats, 10 mg/kg/day resulted in a reduction
in litter weight. In a male fertility study, adult male rats were orally
administered Kepone at a daily dose of 10 mg/kg body weight for 10 days.
The dose-regimen was shortened to 6 days due to the symptoms of severe
neurological impairment before the fifth day. The dosed rats were then
mated with virgin females. Preliminary results indicate that this dose
pattern causes:
137
-------
TABLE 5.23. REPRODUCTION DATA FOR 100 DAYS OF KEPONE-FED AND
CONTROL MICEa
Kepone in
Diet,
ppm
0
10
30
37.5
0
40
Litters
Pair
8
8
8
8
14
14
1st
7
6
4
3
14
0
2nd
5
4
0
0
14
0
Average
young
per
litter
Group A
7.7
7.1
4.7
4.0
Group B
7.1
_*._
Survival ,
Percent
89
87
26
42
89
— —
Pair
days
per
litter
67
80
200
267
50
...
Pair
days
per
young
8.7
11.3
42.1
66.7
7.0
— —
Source: Huber (1965). Reprinted, with permission, from Toxicology
and Applied Pharmacology, (c) Academic Press, Inc. (1965).
Fed indicated diet 1 month before mating and during test period.
^
Fed indicated diet 2 months before mating and during test period.
138
-------
(1) An Immediate and significant loss of fertility expressed as
a capability to impregnate and produce live young. The loss
of fertility is temporary and returns by the third week after
dosing, up to 55 days.
(2) Neurological symptoms (tremors, hyperexcitability) after 4
days1 dosing which continues for about 14 days.
(3) Immediate weight loss with statistically significant dif-
ferences evident 75 days after dosing.
5.3.4.3.6 Placental and lactogenic transfer—Placental and
lactogenic transfer of Kepone has also been documented (Huber, 1965).
After feeding pregnant mice 40 ppm of Kepone in the diet, Huber found an
average of 5 ppm accumulated in seven embryos weighing approximately 0.3
g. This level is comparable to that in the maternal brains but is
considerably lower than the levels found in maternal livers (45 ppm) and
maternal fat (13 ppm). Four placenta averaged 12 ppm Kepone. The body of
a 6-day-old suckling mouse contained 3 ppm Kepone after its mother had
been fed 40 ppm Kepone the previous days.
5.3.4.2.7 Teratogenic effects—Chernoff and Rogers (1976) reported
fetal toxicity in rats and mice exposed to Kepone in utero. Doses of 10,
6, and 2 mg/kg/day of Kepone in rats and 12, 8, 4, and 2 mg/kg/day in
mice were administered to pregnant animals by gastric intubation during
the major period of organogenesis—Days 7 to 16 of gestation. Fetal
toxicity occurred in both rats and mice at doses which caused significant
reductions in maternal weight gains during gestation and increased
liver/body weight ratios. In rats, fetuses from dams receiving the
highest dose (which also resulted in 19 percent maternal mortality)
exhibited significantly higher incidence of low birth weight, reduced
degree of ossification, edema, undesecended testes, enlarged renal
pelvis, and enlarged cerebral ventricles. Lower dose levels, which
produced maternal weight loss and liver/body weight ratio increase but no
mortality, caused only reduced fetal weight and reduced degree of
ossification in offspring. Male rats born to dams treated with Kepone
during gestation showed no reproductive impairment. In the mouse,
fetotoxicity occurred only in the highest dose group and was manifested
by increased fetal mortality and clubfoot.
5.3.4.3.8 Carcinogenic and tumorigenic effects—The National Cancer
Institute (U.W. DHEW,1976) has issued a report confirming the
carcinogenicity of technical grade Kepone in rats and mice. Two levels of
Kepone were adminisstered in the diet of both rats and mice for 80 weeks.
At the beginning of the experiment, dosage for all animals was higher but
was reduced subsequently because the initial dosages were not well
tolerated. The average dosage over the course of the experiment was as
follows:
139
-------
Kepone in Diet, ppm
Mice Rats
High Low High Low
Male 24 8 23 20
Female 26 18 40 20
The rats were sacrificed and autopsied at 112 weeks and the mice at 90
weeks. Clinical signs of toxicity were observed in both species,
including generalized tremors and dermatologic changes. A significant
(P^O.05) increase was observed in the incidence of hepatocellular
carcinomas in rats at the high dose level and mice at both dose levels of
Kepone. The incidences in the high dose groups were 88 percent and 4?
percent for male and female mice, respectively, and 7 percent and 22
percent in male and female rate, respectively (Figure 5.10). No
hepatocellular carcinomas were observed in control rats.
The control mice had 16 percent incidence among males. No
hepatocellular carcinomas were observed in the female controls. Among the
low dose groups of mice, the incidences were 81 percent for males and 52
percent for females, as shown in Figure 5.10. Importantly, the time to
detection of the first hepatocellular carcinoma observed (at death) was
shorter for treated than control mice and, in both sexes of both species,
it appeared to be inversely related to dose. Extensive hyperplasia of the
liver was also found among Kepone-treated animals of both species. The
Kepone-treated animals did not differ significantly from controls as to
tumors in sites other than the liver. This report presents a clear
indication of Kepone's oncogenicity.
Data submitted by Allied Chemical Corporation also indicated that
Kepone is oncogenic in rats (U.S. Environmental Protection Agency,
1976b). Twelve groups of 40 male and female albino rats of an unspecified
strain were fed 0, 5, 10, 25, 50, and 80 ppm Kepone for periods of up to
2 years. Only seven male rats were examined at the 25 ppm dose level.
Four clinical pathologists examined the slides made from the liver
tissues of these treated rats. Liver lesions in one rat were diagnosed as
hepatocellular carcinomas by two pathologists and "evolving carcinomas"
by one pathologist who also found "evolving carcinomas" in a second male
rat at this feeding level. Of the 16 female rats surviving at the 10 ppm
feeding level, liver lesions in three were diagnosed as hepatocellular
carcinomas by one pathologist. Of the nine female rats surviving at the
25 ppm level, liver lesions in one were diagnosed as "evolving
carcinomas" by one pathologist. None of the 23 control rats developed
hepatocellular carcinomas.
140
-------
100-|
§ 60-
i
S 80J
3 70-
P 60*
ui
Z 60
3 40
1 30
u.
O
S 20-1
<
S 10
ui
*" 0
8/49
16%
MALE MICE
39/48
81%
6/19
32%
1
43/49
88%
FEMALE MICE
0/40
or.
26/50
52%
23/49
47%
I
ROOM MATCHED LOW
CONTROL CONTROL OOSE
HIGH
OOSE
CONTROL
LOW
OOSE
HIGH
OOSE
< 100'
§ 80-
u
1 «»-
§ 70-
1 »-
Si
I 60-
£
3 40-
| 30-
o
S 20-
s „
o 10-
t
MALE RATS
A fd •&•• 1/50
0/105 2™
CONTROL ^E
3/44
7%
s>^\
FEMALE RATS
10/45
22X
- 1
0/100 7"? \v
— 0% ji . fi \^^
HIGH rniuTDni LOW HIGH
nOSE CONTROL nnce nne-
FIGURE 5.10. Comparison of incidence of heptocellular carcinoma
in mice and rats following treatment with Kepone
at two levels.
Source: U.S. Department of Health, Education and
Welfare (1976).
lUl
-------
The method of conducting the test, however, may have minimized the
possibility of discovering hepatocellular lesions. In the Allied test,
mice were numbered and survivors of a given numerical sequence were
sacrificed and examined. Also, the smaller survival than observed in the
NCI study at corresponding doses (including controls) means that fewer
animals survived long enough to develop cancer.
-------
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Markin, G. P., H. L. Collins and J. H. Spence. 1974. Residues of the
Insecticide Mirex Following Aerial Treatment of Cat Island.
Bull. Environmental Contam. and Toxicol. 12(2): 233-240.
Mehendale, H. M., L. Fishbein, M. Fields, and H. B. Matthews. 1972.Fate
of Mirex- C in the Rats and Plants. Bull. Environmental Contam.
Toxicol. 8(4): 200-207-
Metcalf, R. L., I. P. Kapoor, P. Y. Lu, C. K. Schuth, and P. Sherman.
1973. Model Ecosystem Studies of the Environmental Fate of Six
Organochlorine Pesticides. Environ. Health Perspect. 4: 35-44.
Mirex Advisory Committee. 1972. Report of the Mirex Advisory Committee
to William D. Ruckelshaus, Administrator, U.S. Environmental
Protection Agency, February 4, 1972. Unpublished Report. 72 pp.
Muncy, R. J., and A. D. Oliver, Jr. 1963. Toxicity of Ten Insecticides
to the Red Crawfish, Procambarus clarki (Girard). Trans. Amer.
Fisheries Soc. 92(4): 428-431.
1U8
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Naber, E. C., and G. W. Ware. 1965. Effect of Kepone and Mirex on
Reproductive Performance in the Laying Hen. Poultry Sci. 44(3):
875-880.
Nimmo, D. R., L. H. Bahnner, R. A. Rigby, J. M. Sheppard, and
A. J.Wilson, Jr. 1976. Mysidopsis bahia; An Estuarine
Species Suitable for Life-Cycle Bioassays to Determine Sublethal
Effects of a Pollutant. In: Prepublications of Kepone in the
Marine Environment, D. J. Hansen, (Ed.). U.S. Environmenmtal
Protection Agency, Office of Research and Development,
Environmental Res. Lab., Gulf Breeze, Florida. (Unpublished).
16 pp.
Pimentel, D. 1971. Ecological Effects of Pesticides on Non-Target
Species. Cornell University, Department of Entomology and
Limnology, Ithaca, New York. Executive Office of the President,
Office of Science and Technology, Washington, D.C. USGPO. 220 pp.
Pittman, K. A., M. Wiener, and D. H. Treble. 1976. Mirex Kinetics in
the Rhesus Monkey. II. Pharmacokinetic Model. Drug Metabolism and
Disposition. 4(3): 288-295.
Schimmel, S. C., and A. J. Wilson, Jr. 1976. Acute Toxicity of Kepone
to Four Estuarine Animals. Chesapeake Sci 18 (2) 224-227-
Schoor, W. P., and S. M. Newman. 1976. The Effect of Mirex on the
Burrowing Activity of the Lugworm (Arenicola cristala). Trans.
Amer. Fisheries Soc. 105(6): 701-704.
Sikka, H. C., G. L. Butler, and C. P. Rice. 1976. Effects, Uptake, and
Metabolism of Methoxychlor, Mirex, and 2,4-D in Seaweeds. Syracuse
University Research Corporation, Syracuse, New York. EPA-600/3-
76-048. U.S. Environmental Protection Agency, Office of Research
and Development, Environmental Res. Lab. Gulf Breeze, Florida.
NTIS. 48 pp.
Smith, J. C., and F. S. Arant. 1967. Residues of Kepone in Milk from
Cows Receiving Treated Feed. J. Econ. Entomol. 60(4): 925-927.
Smrek, A. L., S. R. Adams, J. A. Liddle and R. D. Kimbrough. 1977.
Pharmacokinetics of Mirex in Goats, 1 Effect on Reproduction and
Location.
Stein, V. B., K. A. Pittman, and M. W. Kennedy. 1976. Characterization
of a Mirex Metabolite from Monkeys. Bull. Environmental Contain.
Toxicol. 15(2): 140-146.
Tagatz, M. E. 1976. Effect of Mirex on Predator-Prey Interaction in an
Experimental Estuarine Ecosystem. Trans. Amer. Fisheries Soc. 105
(4): 546-549.
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Tucker, R. K., and D. G. Crabtree. 1970. Handbook of Toxicity of
Pesticides to Wildlife. U.S. Dept. of the Interioor, Bureau of
Pish and Wildlife, Denver Wildlife Research Center, Denver,
Colorado. Resource Publication No. 84. USGPO. pp. 1-9, 82-83.
U.S. Department of Health, Education, and Welfare, National Institutes
of Health. 1976. Report on Carcinogenesis Bioassay of Technical
Grade Chlordecone (Kepone). National Cancer Institute, Division of
Cancer Cause and Prevention, Carcinogenesis Program. 25 pp.
U.S. Environmental Protection Agency, Office of Pesticide Programs,
Criteria and Evaluation Division. 1975. Kepone. Unpublished
Report. 24 pp.
U.S. Environmental Protection Agenccy. 1976a. Preliminary Report on
Kepone Levels Found in Human Blood from the General Population of
Hopewell, Virginia. Health Effects Res. Lab. Research Triangle
Park, North Carolina. Unpublished Report. 16 pp.
U.S. Environmental Protection Agency. 1976b. CRPAR Checklist - Active
Ingredient. Chlordecone (Kepone). Unpublished, Internal working
document. 15 pp.
Van Valin, C. C., A. K. Andrews, and L. L. Eller. 1968. Some Effects of
Mirex on Two Warmwater Fishes. Trans. Amer. Fisheries Soc. 97(2):
185-196.
Walsh, G. E., K. Ainsworth, and A. J.Wilson, Jr. 1976. Toxicity and
Uptake of Kepone in Marine Unicellular Algae. Chesapeake Sci 18
(2) 222-223.
Ware, G. W., and E. E. Good. 1967. Effects of Insecticides on
Reproduction in the Laboratory Mouse. II. Mirex, Telodrin, and
DDT. Toxicol. Appl. Pharmacol. 10: 54-61.
Waters, E. W. 1976. Mirex: I. An Overview. II. An Abstracted Literature
Collection. 1947-1976. ORNL/TIRC-76/4. Oak Ridge National
Laboratory, Oak Ridge, Tennessee. 98 pp.
Wiener, M., K. A. Pittman, and V. Stein. 1976. Mirex Kinetics in the
Rhesus Monkey. I. Disposition and Excretion. Drug Metabolism and
Disposition 4(3): 281-287-
Woodham, D. W., C. A. Bond, E. H. Ahrens, and J. G. Medley. 1975. The
Cumulation and Disappearance of Mirex Residues. III. In Eggs and
Tissues of Hens Fed Two Concentrations of the Insecticide in Their
Diet. Bull. Environmental Contain. Toxicol. 14(1): 98-104.
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6.0 EFFECTS ON HUMANS
6.1 SUMMARY
Human exposure to Kepone and/or mi rex has been documented through
somewhat limited monitoring programs, epidemiologic and medical
surveillance of workers engaged in the manufacture of Kepone, a
systematic epidemologic survey of a community where Kepone was
manufactured, and analytical confirmation of residues of both pesticides
in human tissues and man's food chain.
Potential sources of exposure of humans to mirex are believed to be
related to mirex bait application in fire ant control programs. In
general, positive identification of mirex in foods and human tissue
samples coincides with the areas of heaviest mirex usage. While it is
probable that the primary exposure mode in general populations is through
diet, there is insufficient information on the mechanisms of transfer of
mirex in the environment to rule out the possibility that exposures via
air, water, or dermal routes may be important. Where possible, detailed
investigations of the habits (diet, occupation, etc.) of individuals
submitting positive specimens would aid greatly in definitely
establishing the sources as well as the mechanisms of exposure.
The extreme resistance of mirex to degradation and metabolism
indicates the potential for environmental stability and biomagnification.
Not unexpectedly, mirex residues in humans have been found in a survey of
adipose tissue. To date, approximately 284 samples of adipose tissue of
persons from areas of the U.S. treated for fire ant control have been
analyzed and about 17 perecent of them had quantifiable levels of mirex.
Trace amounts have been found in an additional 2 percent of the samples.
The mirex concentrations ranged between trace and 1.3 ppm on a wet basis.
Generally, those areas having the highest percentages of tissues positive
for mirex corresponded to the areas having a history of the heaviest
mirex usage.
The five main potential sources of human exposure to Kepone are: (1)
household use of ant and roach baits containing Kepone, (2) occupational
exposures, i.e., workers employed in Kepone production or agricultural
workers who apply the insecticide to banana and tobacco crops, (3)
accidental ingestion of agricultural formulations, (4) contaminated soil,
water, or air, and (5) contaminated food.
Of 298 samples of human mothers' milk gathered in the southeastern
U.S. by the Environmental Protection Agency during FY 1977, 9 showed
Kepone levels ranging from less than 1 ppb to 5-8 ppb. EPA stated that it
is uncertain at this time what hazards, if any, are posed by these levels.
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The Health Effects Research Laboratory (HERD of the Environmental
Protection Agency has reported the results of two preliminary studies on
Kepone levels found in human blood and sebum from residents of the
Hopewell, Virginia, area. The Kepone source was traced to Life Sciences
Products Company (LSPC), the nation's sole manufacturer of Kepone. A high
blood Kepone level (7.5 ppm) of a worker led to a detailed investigation
of present and former LSPC employees.
Between March, 1975, and July, 1976, interviews, examinations, and
blood specimens were obtained from all 33 current employees and 100
former workers (a coverage of 90 percent of all persons who had worked at
LSPC). These data indicated that of the 133 workers studied, 76 had
contracted an illness chemically compatible with Kepone toxicity, 49 had
neurological symptoms with or without subjective symptoms, and 27 had
subjective symptoms only. Evidence of symptoms was much higher among
production personnel (64 percent) than among other employees not directly
involved in production (16 percent).
Studies by Guzelian, et al., at the Medical College of Virginia
suggest that symptoms of toxicity in LSPC employees were observable as
early as 1 week after beginning work and persisted after termination of
exposure up until the time of examination. Of the LSPC employees
examined, 17 were symptomatic and had whole blood Kepone concentrations
ranging from 1.5 to 26.0 ppm with a mean of 8.3 ppm. Blood assay of the
asymptomatic group showed a 1.8 ppm mean concentration of Kepone. Since
over 50 percent of these workers had blood levels in the lower range of
values for the symptomatic group, blood levels cannot be considered a
sensitive diagnostic test in this population. Lower blood levels
typically seen in these persons may reflect removal of Kepone from the
blood to storage areas in body fat or liver. High hepatic concentrations
of Kepone suggest that: (1) the pesticide may undergo biotrans format ion
in the liver, and (2) transport of Kepone and its metabolites into bile
could serve as important routes of excretion. The most pronounced
physiological effects of Kepone intoxication are neurological impairment,
significant hepatomegaly, and dysfunction of the endocrine and metabolic
systems, the latter two resulting in sterility, weight loss, and
irritability.
Therapy with selected ion exchange resins which are capable of
precipitating Kepone from bile may be efficacious in treatment of Kepone
poisoning, particularly if administered soon after Kepone ingestion.
A systematic survey by HERL to establish the geographic limits of
the Kepone exposure area in Hopewell showed that of the 216 blood samples
analyzed, 40 (approximately 19 percent) contained 5 to 50 ppm Kepone.
Thirty-four of these 40 samples were from people in the residential area
within 400 meters of LSPC. Two additional samples having detectable
Kepone were from people living in the apartment building to the north of
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LSPC, and the remaining four were from people residing 800 or more meters
from the plant. The remaining 176 samples contained a nondetectable
amount (less than 5 ppb) of Kepone.
Human sebum samples which were collected from hospitalized workers
from LSPC contained 0.2 to 3.0 micrograms of Kepone whereas there was no
detectable Kepone in samples from the general population. Sebum from some
of the nonhospitalized workers contained 0.05 to 0.8 micrograms of Kepone.
The established tolerances for mirex are 0.1 ppm (negligible
residue) in the fat of meat of cattle, goats, hogs, horses, poultry, and
sheep; 0.1 ppm (negligible residue) in milk fat and eggs; and 0.01 ppm
(negligible residue) in or on all other raw agricultural commodities.
In order to determine the fate of mirex in cattle grazing on treated
pastures, the U.S. Department of Agriculture analyzed 1000 samples of
subacutaneous fat from 5 different locations on the carcasses. Residues
were found in 88 percent of the samples with levels ranging from 0.0001
to 0.125 ppm, and an average value of 0.026 ppm. Only one sample, 0.125
ppm, contained in excess of the established tolerance of 0.1 ppm for
mirex in the fat of beef cattle. Milk from cattle in treated areas may
contain minute quantities of mirex; but the amounts are at least 100
times lower than the presently established levels for milk.
From the large reservoir of fish data which have been reported
concerning mirex in Lake Ontario and its tributaries, the U.S. Food and
Drug Administration (FDA) found that a significant number of species of
fish exceed the present FDA standard of 0.1 ppm. Fish with high mirex
concentrations also had high PCB levels.
FDA's surveillance of South Atlantic and Gulf Coast states indicated
that none of the assays showed detectable mirex in shellfish and
crustaceans in Alabama, Louisiana, Georgia, northeast Florida,
Mississippi, and South Carolina. In the case of finfish, however, all
surveys except the Texas survey revealed some samples with detectable
mirex levels (in Alabama, Arkansas, Louisiana, and Mississippi).
Kepone has been found in freshwater trout (0.15 to 0.17 ppm) and
suckers (0.18 ppm) taken from Spring Creek, which runs near the Nease
Chemical Plant, State College, Pennsylvania, a former producer of Kepone
(1958-59 and 1963) and mirex, as late as 1974.
The observation of high levels of Kepone (0.02 to 14.1 ppm) in fish,
shellfish, and crabs from the Hopewell, Virginia, area, together with the
findings of high levels of Kepone (1.4 ppm) in sediments from various
James River locations, prompted an EPA ban (December 17,1975) on taking
fish, shellfish, and crabs from the James River and its tributaries from
Richmond to Chesapeake Bay.
EPA has recommended to the FDA the following "action" levels: 0.3
ppm of Kepone in the edible portion of shellfish (oysters and clams), 0.1
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ppm in finfish, and 0.4 ppm in crabs. These values are intended to serve
as temporary levels of pesticide residues to be used as enforcement
guides. EPA has also recommended a 0.03 ppm action level in processed
oyster stew. Under usual action level procedures, the highest amount of a
toxic chemical found not to cause chronic toxic effects in test animals
is established, and reduced by a factor of 1/100. However, because of
public concern with Kepone, a safety factor of at least 1/1000 was used.
Control of the banana root borer comprised the only food or feed use
of Kepone. Original tolerance (now revoked) was 0.01 ppm in or on the
fruit, although evidence submitted with the registration petition
indicated that residues, if any, in the edible pulp would be less than
the lowest detection level (0.005 ppm).
The possible carryover from soils to other crops of Kepone used to
control wireworms in tobacco fields has not been investigated.
This section focuses on the epidemiology and toxicology of human
exposure to mirex and Kepone. The doses to the U.S. population in general
and to specific subgroups potentially most at risk have been estimated in
another recent study (Suta, 1977) based in part on the findings of this
investigation.
6.2 SOURCES OF POTENTIAL EXPOSURE TO MIREX
Data obtained from the U.S. Department of Agriculture (Personal
communication, 1977) show that approximately 186,000 kg (410,100 Ib) of
mirex were applied between 1962 and 1973 in Federal-State cooperative
programs to control the imported fire ant (Table 2.4). The heaviest usage
has occurred in the states of Alabama, Florida, Georgia, Louisiana and
Mississippi; mirex has also been used in lesser amounts in Arkansas,
North Carolina, South Carolina and Tennessee. Its resistance to chemical,
thermal and biochemical degradation along with evidence from animal
studies suggest that mirex may be highly bioaccumulative. Sampling
programs involving analysis of human tissue and foods have been initiated
to define the extent of human exposure. In general, positive
identification of mirex in foods and human tissue samples coincide with
the areas of heaviest mirex usage. Surveys of wildlife conducted in areas
most heavily treated with mirex have revealed highest concentrations of
mirex in predatory fish, birds and game, which if consumed by man, could
represent important sources of exposure to mirex. However, levels of
mirex in commercially raised food products, on the other hand, have
usually been well below the established tolerances.
Little information was found on air, water or dermal mirex
exposures. With the exception of persons directly involved in manufacture
or application of the product, the contribution of these sources to total
exposure is probably minimal; however, the importance of these potential
exposure routes cannot be definitely ruled out.
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Currently available data are inadequate for a thorough appraisal of
human exposure to mirex. Three very essential problems preclude such an
assessment:
(1) Presently, the fate of mirex once it enters the environment
cannot adequately be specified; information on the mechanisms
of transfer through the environment is lacking.
(2) Mirex is indistinguishable from the chemically identical pro-
duct, Dechlorane, which is used extensively as a flame
retardant. The patterns of usage and distribution of Dechlorane
in the environment are unknown. Consequently, mirex residues in
some cases may stem from flame-retardant uses rather than fire
ant control usage.
(3) The location of application of almost half of the mirex (sold
during 1962-1973) cannot be accounted for.
6.2.1 Mirex in Human Tissues
The extreme resistance of mirex to degradation and metabolism
indicates the potential for environmental stability and biomagnification.
Not unexpectedly, mirex residues in humans have been found in surveys of
adipose tissue conducted by the National Human Monitoring Program for
pesticides.
The Ecological Monitoring Branch, Technical Services Division, of
the U.S. Envionmental Protection Agency operates several of the component
programs of the Interagency National Pesticides Monitoring Program. The
basic operation and scope of the adipose survey remain unchanged from the
original program as described by Yobs (1971) except that the same human
tissue samples formerly analyzed for mirex will also be analyzed for
Kepone. In addition, blood serum samples obtained from the Health and
Nutritional Examination Survey will also be analyzed for mirex (Anon.,
1976a). Data from this program are indicative to some degree of
environmental contamination and distribution of this chemical. Since the
human monitoring survey operates on a national scale, the stratification
by census division or region does not conform to the area in which mirex
has been used. The national scope of the human monitoring survey is
incompatible with precise estimations of the chemical epidemiology of
mirex (Kutz and Strassman, 1976).
A special monitoring program has been designed to collect
representative samples of human adipose tissue from residents of areas
with a history of mirex applications to determine the incidence and
residue levels of mirex. Forty collection sites scattered through the
southeastern states were selected for the survey. Adipose tissue samples
for this project were obtained through the co-operation of medical
pathologists and examiners located in cities within the collection areas.
Tissues were taken from surgical specimens previously excised for
pathological examination and from postmortem examinations. Since tissues
155
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representative of the general population were requested, patients having
a diagnosis of known or suspected pesticide poisoning, cachetic patients,
and individuals institutionalized for long periods were excluded from the
sampling. To date, approximately 284 samples of adipose tissue have been
analyzed and about 17 percent of them had quantifiable levels of mirex as
determined by electron capture gas chromatography (Anon., 1976b). Trace
amounts have been found in an additional 2 percent of the samples. The
mirex concentrations range between trace and 1.32 ppm on a wet weight
basis. By state, the number of samples and the percentage positive for
mirex are:
State Number of Samples Positive Samples, Percent
Louisiana 4? 40
Mississippi 28 32
Georgia 51 24
Alabama 27 11
S. Carolina 17 6
Florida 53 6
Texas 52 0
N. Carolina 9 0
Generally, those states having the highest percentages of tissues
positive for mirex corresponded to the areas having a history of the
heaviest mirex usage. For example, Louisiana, Mississippi, and Georgia,
which ranked first, second, and third were also the three highest states
in terms of aggregate acres treated with mirex under federally assisted
fire ant control programs (Table 2.4). Perhaps more relevant is the fact
that these same three states had the largest number of acres treated in
1973, the most recent year for which data were available (U.S. Department
of Agriculture, 1977).
6.3 SOURCES OF POTENTIAL EXPOSURE TO KEPONE
The five main potential sources of human exposure to Kepone are: (1)
household use of ant and roach baits containing Kepone, (2) occupational
exposures, i.e., workers employed in Kepone production or agricultural
workers who apply the insecticide to banana and tobacco crops, (3)
accidental ingestion of agricultural formulations (mainly by children),
(4) contaminated soil, water or air, and (5) contaminated food.
The major use of Kepone in the continental United States is as a
roach and ant bait in houses and on lawns and gardens. Several
registrations for Kepone bait formulation enclosed or not enclosed in
traps, provide for general applications along baseboards, shelves, sills,
or wherever ants may appear. Label directions do not always limit the
amount of Kepone bait that can be applied to a single room. Although the
labels provide a warning not to apply in areas accessible to children or
domestic animals, the direction to apply where ants appear could result
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in application in areas clearly accessible (U.S. Environmental Protection
Agency, 1975a).
A search of the Pesticide Episode Review System (PERS) data file
identified 56 non occupational cases of human poisoning involving the
active ingredient Kepone (Davida, 1976). Of these, 52 involved children
under 5 years of age, two involved adults (17 to 65), and two specified
no age. Of the 52 episodes involving children under five, 43 occurred in
the home. Nine did not indicate a location. All home-related episodes
involved products designed to control household insect pests, primarily
ants and roaches. The majority of these involved children who found the
pesticide (presumably contained in bait traps) and placed it into their
mouths. No symptoms were listed in any of these instances. Several
reports stated that treatment rendered was precautionary rather than in
response to symptoms. Of the two episodes involving adults, one was an
attempted suicide and the other a job related incident in which a man who
worked in a pesticide packaging plant developed dermatitis on his hands.
No fatalities were reported involving the active ingredient Kepone. The
only health efffect noted in any of the reports was dermatitis.
Another use entailing human exposure is the use of 5 percent dust on
banana plants in Puerto Rico. As noted on the Candidate for Rebuttable
Presumption Against Registration (CRPAR) checklist (U.S. Environmental
Protection Agency, 1976b) there is only one registered product having
this use. Directions call for surface application of 8 Ib of active
ingredient per acre and allow for application at 6 month intervals. The
registered product label specifying this use prescribes a respirator for
workers. Thus, the hazard posed by this use depends upon the degree of
compliance with label directions. The direct hazard to humans would be a
chronic dermal or inhalation effect.
Data on environmental levels of Kepone are available only from
heavily contaminated areas; the hazards to general populations outside
the contaminated areas are discussed in Section 7- Low levels of Kepone
excreted into human milk are suggestive of the possibility of generalized
sources of exposure; however, these have not yet been traced (See Section
6.4.1.)
6.3-1 Kepone in Human Tissues and Fluids
Recent tests by the Environmental Protection Agency have uncovered
minute amounts of Kepone in samples of human mother's milk taken in the
southeastern United States (Anon, 1976c). Of 298 samples gathered by EPA
during FY 1976, nine showed Kepone levels ranging from less than 1 ppb to
5.8 ppb. EPA said it was uncertain at this time what hazards, if any, are
posed by these levels. The nine milk samples were taken from women
residing in Atlanta, Georgia; Whittier, North Carolina, and five Alabama
communities: Birmingham, Cullman, Decatur, Huntsville, and Mobile. Milk
sampling was also conducted in six other states—Arkansas, Florida,
Louisiana, Mississippi, South Carolina, and Texas—but no Kepone was
found in these areas.
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It is unknown whether mirex is the precursor of the Kepone in the
milk samples. EPA will conduct tests to see whether it can confirm USDA's
findings on the connection between the pesticides. The agency is also
conducting background checks on the women with positive results to
determine whether the Kepone may have come from sources other than mirex.
Results from the National Pesticides Monitoring Program on Kepone
levels in human tissues have not yet been reported; information from
areas having no history of mirex application should help clarify whether
mirex is the source of Kepone in milk and tissue samples.
6.4 ACUTE EXPOSURE TO KEPONE
The Health Effects Research Laboratory (HERL) of the U.S.
Environmental Protection Agency has reported the results of two
preliminary studies on Kepone levels found in human blood and sebum from
residents of the Hopewell, Virginia, area (U.S. Environmental Protection
Agency, 1975b and 1976a).
On August 7, 1975, EPA was first alerted to the possibility of a
pesticide exposure problem in Hopewell when a worker at the Life Sciences
Products Company (LSPC), the nation's sole manufacturer of Kepone,
experienced neurological symptoms and contacted a local internist (U.S.
Environmental Protection Agency, 1975b). Recognizing the possibility of
an occupational exposure, a blood sample of the worker was submitted for
analysis. When a high Kepone level of 7-5 ppm was found in the blood
sample the patient was immediately admitted to the Medical College of
Virginia Hospital, and the Virginia State Health Department was informed.
With the aid of the Center for Disease Control in Atlanta, Georgia, an
investigation of present and former employees of LSPC was promptly begun.
6.4.1 Epidemiology of Kepone Poisoning
Between March, 1974, and July, 1975, 76 (57 percent) of the workers
at Life Sciences Products Company (LSPC) contracted an illness clinically
compatible with Kepone toxicity. The principal manifestations of the
disease were nervousness, tremor, weight loss, opsoclonus, (erratic or
"jumpy" eye oscillations), and pleuritic chest pain. As shown in Table
6.1 workers exhibited a syndrome closely resembling that seen in animals
suffering from Kepone exposure (Center for Disease Control, 1976).
Of a total of 148 persons who had worked at LSPC since it opened, 33
were employed at the time the plant closed. Interviews, examinations, and
blood specimens were obtained from all 33 current employees and 100 of
the 115 former workers, representing a coverage of 90 percent of all
persons who had worked at LSPC. Of these 133 workers studied, 76 were
affected; 49 had a neurologic abnormality with or without subjective
symptoms and 27 had subjective symptoms only. Attack rates were much
higher among production personnel (64 percent). Rates of Kepone poisoning
are classified according to job category in Table 6.2.
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TABLE 6.1. SUMMARY OF TOXIC EFFECTS OF KEPONE
IN HUMANS AND ANIMALS3
Animals
Humans
Excitability
Tremor
Loss of weight
Dermatologic changes
Testicular atrophy
Increased liver-to-tody
weight ratio
Increase in hepatocellular
Nervousness
Tremor, ataxia
Loss of weight
Skin rash
Sterility
Abnormal liver function
Opsoclonus
Joint pain
Pleuritic pain
Adapted from Center for Disease Control, (1976).
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TABLE 6.2. KEPONE POISONING ATTACK RATES BY JOB CATEGORY0
ON
o
Current Workers
Cases
Secretarial/Office 0
Janitorial 2
Maintenance 4
Pad Men 1
Lead Operators/ 7
Foremen
Dryer and Filler 6
Operators
Total 20
Total
5
4
7
1
9
7
33
Attack
Rate,
percent
0
50
57
100
78
86
61
Former Workers
Cases
0
1
14
3
9
29
56
Total
4
6
28
6
13
43
100
Nonproduction
Attack
Rate,
percent
0
17
50
50
68
67
56
Workers
Production Workers
Total
Total Workers
Cases
0
3
18
4
16
35
76
3
73
76
Total
9
10
35
7
22
50
133
19
114
133
Attack
Rate,
percent
0
30
51
57
73
70
57
16
64
57
Adapted from Center for Disease Control (1976).
-------
Limited ambient air measurements have been made in the LSPC facility
but are insufficient to adequately define exposure levels of Kepone. The
data available indicate that levels probably were in the range of 0.016
to 3-0 mg/m . Workers involved in the drying operations and presumably
exposed to 3-0 mg/m levels had blood Kepone levels of 5 to 60 ppm. These
workers had a 65 percent attack rate. This compares with a mean level of
Kepone of 8.48 ppm measured in the blood of 7 of the 10 workers actively
employed and having signs of Kepone poisoning at the time the survey was
conducted. The remaining three asymptomatic individuals had mean blood
Kepone levels of 1.57 ppm.
Table 6.3 shows the ranges and means of blood Kepone levels for
various groups tested. Data on Hopewell area residents come from a
community survey more fully discussed in Section 6.4.4 and are included
here for comparative purposes only. Interpretation of blood Kepone levels
and symptoms for the groups of exposed individuals other than LSPC
workers is difficult. Blood Kepone levels of these persons were much
lower than those of LSPC workers, and their exposure was much less
certain. Family members were exposed either by general air pollution in
the vicinity of the plant or through dust carried home on the clothing of
workers. Sewage-treatment-plant workers were exposed through work on the
Hopewell sewer system that had been contaminated with Kepone. Cab drivers
were exposed through dust on the clothing of workers whom they drove home
from work.
The workers for Allied Chemical Corporation who had been employed in
earlier Kepone production at the Allied semiworks plants present an
interesting comparison group. They were occupationally exposed to Kepone
and would be expected to have health problems analogous to the LSPC
workers; however, several factors were different. Kepone was produced
only a few months each year at Allied rather than continuously; workers
described a much cleaner operation at Allied than at LSPC; and there
appeared to have been far less employee illness at the Allied plant than
at the LSPC plant. Five of the 39 Allied workers who were exposed at
least 16 months before blood sampling exhibited possible Kepone toxicity;
of these five, four demonstrated a neurologic abnormality consistent with
Kepone toxicity, and one of them complained of a complex of systems
consistent with Kepone toxicity. However, at the time of examination
three had nondetectable blood Kepone levels, and the other two had levels
of only 0.009 ppm and 0.02 ppm. Blood levels in these Allied workers
might be low or nondetectable because Kepone had been stored in toxic
concentrations in other parts of the body (fat,brain, and liver) or
excreted from the body after causing residual tissue damage (Center for
Disease Control, 1976).
6.4.2 Clinical Findings in LSPC Workers
Understanding the clinical manifestations of Kepone toxicity and of
instituting rational therapy has been hampered by the lack of precedent
in humans and because little information on the topics of Kepone
161
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TABLE 6.3. BLOOD KEPONE LEVELS BY GROUPS OF EXPOSED PERSONS'
H
o\
ro
Group
Affected LSPC workers
Unaffected LSPC workers
Family members of
LSPC workers
Allied Chemical
Repone workers
Neighborhood workers
Sewage treatment
plant workers
Cab drivers
Truck drivers
Hopewell residents
Number
Tested
57
49
32
39
32
10
5
2
214
Number
With
Detectable
Levels
57
48
30
30
23
6
1
1
40
Percent
With
Detectable
Levels
100
99
94
77
72
60
20
50
19
Range of
Detectable
Levels, ppm
0.009-11.8
0.003- 4.1
0.003- 0.39
0.003- 0.45
0.003- 0.031
0.004- 0.014
0.003
0.004
0.005- 0.0325
Means of
Detectable
Levels, ppm
2.53
0.60
0.10
0.06
0.011
0.008
0.003
0.004
0.011
Adapted from Center for Disease Control (1976).
-------
distribution, biotransformation and excretion is available from animal
studies.
The only infprmation on the metabolic characteristics and effects of
Kepone in humans comes from studies of exposed workers at Hopewell,
Virginia. As part of an ongoing study of the toxicity and
pharmacokinetics of Kepone at the Medical College of Virginia,Guzelian,
et al., (1975) have reported clinical findings of 32 employees of LSPC
who were examined for symptoms and signs of Kepone associated toxicity.
The period of exposure of affected workers ranged from 3 to 18 months,
with symptoms often appearing as early as 1 week after beginning work at
LSPC and persisting after termination of exposure up until the time of
the examination.
6.4.2.1 Blood Levels—
Of the LSPC employees examined, 17 were symptomatic and had whole
blood Kepone concentrations ranging from 1.5 to 26.0 ppm with a mean of
8.3 ppm. In the asymptomatic group, the mean concentration of Kepone in
the blood was 1.78 ppm. Since over 50 percent of these workers had blood
levels in the lower range of the values for the symptomatic group, blood
levels are not considered a sensitive diagnostic test in this population.
Similar examinations of 81 former employees identified 33 additional
suspected cases of Kepone toxicity. Significant amounts of Kepone have
been found in the blood of family members and even household pets of some
of the affected workers.
Results of a similar analysis of blood specimens from workers at
LSPC were also reported by the Center of Disease Control Toxicology
Branch (Center for Disease Control, 1976). The blood Kepone levels
observed in the workers exhibiting signs of toxicity ranged from 0.009 to
11.8 ppm, whereas those for asymptomatic workers ranged from
nondetectable to 4.1 ppm. The mean Kepone blood level in poisoned workers
was significantly different from that of persons in the non poisoned
category: 2.53 versus 0.60 ppm, respectively. Several persons with
neurologic symptoms had relatively low blood levels, however.
6.4.2.2 Tissue Levels—
The CDC does not feel that Kepone levels in blood accurately reflect
body burden or potential for toxicity, especially among former workers no
longer exposed to Kepone, since lower blood levels typically seen in
these persons may reflect removal of Kepone from the blood to storage
areas in body fat or liver. Also, in persons who continue to manifest
neurologic symptoms without continued exposure, the Kepone level may have
dropped below the limit of detection in the blood, but Kepone may have
caused irreversible damage or may still be present in toxic concentration
in the brain or other organs. Table 6.4 reveals the inconsistency in
blood and tissue levels in severely affected workers, illustrating the
inability of blood levels to reflect the full body burden of Kepone.
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TABLE 6.4. KEPONE LEVELS IN VARIOUS TISSUES OF KEPONE WORKERS3
Patient
1
2
3
4
Serum
0.4
5.6
6.0
9.45
Liver
5.3
81.4
173.0
81.0
b
Kepone Concentr at ion ., , ppm
Cerebrospinal
Fat Urine Fluid
0.015
0.020 0.028
50.0 — 0.021
52.0 — 0.027
Saliva
0.125
1.49
—
0.54
a Adapted from Center for Disease Control (1976).
Analyses performed by Consolidated L
Virginia State Department of Health.
Analyses performed by Consolidated Laboratory Services,
-------
6.4.2.3 Metabolism of Kepone—
Studies at the Medical College of Virginia have shown not only a
wide range of blood Kepone concentrations among the hospitalized workers,
but also considerable fluctuations of blood Kepone levels within
individuals. One possible explanation of this variability may be that the
small quantity of Kepone present in extracellular fluids equilibrates
with the bulk of the highly lipophilic compound which is sequestered in
tissue lipids and membranes. Higher concentrations of Kepone in liver and
fat than in blood, shown by this preliminary study (Guzelian, et al.,
1975), may imply that Kepone is stored preferentially in tissue
reservoirs. The high hepatic concentration of Kepone suggests that the
pesticide may undergo biotransformation in the liver and that transport
of Kepone and its metabolites into bile could serve as important routes
of excretion. Consistent with this hypothesis, Kepone has been detected
in both the feces and bile of the hospitalized patients.
The extent of biotransformation of Kepone in humans remains
unanswered. Dr. R. V. Blanke at the Medical College of Virginia (cited in
Guzelian, et al., 1975) has found unidentified halogenated hydrocarbon
compounds other than Kepone in gas chromatographic analysis of blood and
urine. These findings are equivocal concerning Kepone metabolism,
however, because these compounds could either represent products of
Kepone metabolism or could be related to the halogen-containing
antianxiety benzodiazepine drugs that many of the patients were taking at
the time of sampling. Among patients who received no halogenated drugs,
the unidentified compounds were not detectable in blood, urine, or liver.
6.4.2.4 Effects—
The most pronounced physiological effects of Kepone intoxication
relate to the neurologic systems, the liver and the endocrine system.
6.4.2.4.1 Neurological effects'—The most prominent symptom in the
great majority of the patients was neurological impairment. Tremors,
jumpy eye movement (opsoclonus), exaggerated startle response, and
various forms of cerebellar dysfunction were the most typical neurologic
manifestations (Guzelian, et al., 1975). Results of electromyography and
nerve conduction studies were normal in most cases, although there was
some evidence of neuropathy and myopathy. Electron microscopy examination
gave evidence of peripheral neuropathy, and deposits of unidentified
material were present in some gastrocnemius and sural nerve biopsies. The
nature of these ultrastructural changes is discussed in detail by
Martinez, et al., (1976).
6.4.2.4.2 Hepatotoxic effects—Although a majority of patients had
significant hepatomegaly, the extent of liver involvement in these
patients was generally mild. Signs of acute or chronic liver failure or
portal hypertension have not been observed. A two-to threefold elevation
of alkaline phosphatase was present in about one-third of the patients
while the other liver-function tests typically yielded normal results.
165
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Liver histology in 12 patients revealed increased fat, numerous dense
bodies and a proliferation of smooth endoplaamic retioulum.
6.1.2.11.3 Reproductive effeots--3terllity was the most striking
abnormality of the endocrine and metabolic system. Anderson, et al.,
(1976) hypothesized that the underlying cause of infertility may be
maturation arrest (which has been associated with administration of
organic pesticides in animals). Anderson, et al., (1976) examined 16 LSPC
workers who exhibited evidence of neurologic hepatic and testloular
dysfunction from prolonged exposure to Kepone. Sperm counts obtained in
seven patients revealed azospermia in one previously fertile patient and
counts of less than 20 million in five others. All seven had less than 20
perroent motility and increased abnormal forms. Three of these patients
also have abnormally small testes, and testloular biopsies revealed a
generalized maturation arrest. Although eight of the sixteen patients had
decreased libido, testosterone levels were normal in five patients and
elevated in two. Follicle stimulating hormone (PSH) and luteinlzing
hormone (LH) levels were found to be normal. Blood Kepone levels and
sperm counts correlated poorly, however, such a finding was not
unexpected in view of the poor correlation between blood and tissue
Kepone levels (Anderson, et al., 1976).
Prompted by the findings of infertility and dramatic weight loss In
the presence of normal or increased food Intake, Ouzelian, et al., (1975)
conducted a detailed investigation of endocrine and other metabolic
functions of the Kepone poisoned workers, discussed in the following
section. The authors have speculated that the features of restlessness,
irritability, tremulousness and weight loss in the absence of evidence of
malabsorption or decreased appetite might be accounted for by the
presence of a "hypermetabolic" state.
6.4.2.5 Treatment--
One study by Cohn, et al., (1976), suggests that therapy with resins
(i.e., cholestryamlne) which are capable of precipitating Kepone from
bile may be efficacious in treatment of Kepone poisoning. It appears that
oholestryamine facilitates excretion by inhibition of intestinal
blotransformation or prevention of reabsorption of Kepone in the
intestine following excretion into the bile.
The findings of a preliminary study of 32 hospitalized workers
poisoned after chronic exposure to large quantities of Kepone have been
reported by Cohn, et al., (1976). Significant findings include: (1)
abnormal liver histology, specifically increased fat, dense bodies and
proliferation of smooth endoplasmio retioulum; (2) high concentrations of
Kepone in liver, whole blood and auboutaneous fat as shown in Table 6.5.
(3) a partition of Kepone between fat and blood (mean • 7•1:1) 10 to 20
times lower than that reported for other lipophilic chlorinated
hydrocarbons; (H) failure to identify metabolites of Kepona In tissue,
urine, or feoea; (5) negligible excretion In urine and sweat; (6) the
principal route of excretion of Kepone la the feoes.
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TABLE 6.5. TISSUE DISTRIBUTION OP KEPONE IN HOSPITALIZED WORKERS8
Tissue
Liver
Whole blood
Number
of Samples
10
32
Kepone Concentration, ppm
Mean
75.9
5.8
Range
13.3-173.0
6.6-32.0
Suboutaneoua
fat 16 21.5 2.2-62.0
a Source: Conn, et al., (1978). Reprinted, with
permission from the New England Journal of Medicine.
(o) The Massachusetts Medical Society (1978)
Kepone was eliminated In the feoes of 15 patients at a mean dally
rate of 0.075 percent (range 0.019 to 0.279 percent) of the estimated
total stores of Kepone. However, fecal excretion accounted for only 10
percent of biliary excretion of Kepone, as estimated from samples of
duodenal drainage. These differences suggest that Kepone may be converted
In the Intestine to unmeasured chemical species and/or may undergo
enterohepatlc circulation. The latter hypothesis was evaluated In a
clinical trial of oholestryamine therapy recently reported by Conn, et
al., (1978).
Approximately 12 months after their Initial evaluation, 29 of the
original group of 32 LSPC workers participated In a randomized trial of
oral oholestryamine therapy. The men were stratified Into three groups
according to blood Kepone level at entry to the study. The "high" group
consisted of 10 men having blood Kepone levels of grater than 1000
ng/liter (10 ppm). "Medium" and "low" groups consisted of ten men having
blood Kepone levels of 5-10 ppm and nine men having blood Kepone levels
of 1-5 ppm, respectively. Within each of these groups, the men were
randomly allocated to treatment with either oholestryamine or a placebo.
Patients were treated for 5 months (placebo or oholestryamine, 36
grams per day). The participants were examined biweekly and samples were
taken of blood, subcutaneous fat and urine. The drug was well tolerated
and in 11 of the 12 patients treated with oholestryamine, an accelerated
rate of disappearance of Kepone from the blood was observed relative to
each patients rate during the pretreatment "control" period. The average
half-life of Kepone In the blood for patients given oholestryamine was
80+ l) days, a significant reduction compared to 165 + 27 days observed in
the* control period. On the other hand, the average half-life of patients
treated with a placebo was unchanged from their pretreatment values.
Choleatryamine had a dramatic effect in stimulating the rate of
Kepone excretion in the stool as shown in Figure 6.1. (Control
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collections of stool were obtained from each patient for at least 72
hours. Treatment with cholestryamine was started, and 48 hours later,
stool was collected for a second 72-hour period).
|f 6.0
O 5.0
5 4.0
X
IU
Ul 3.0
§20
5-
,-n
r
CHOLESTYR6MINE BB
(2«9/d)
CONTROL CH
JB
9 10 II IZ 13
PATIENT
14
Figure 6JL. Stimulatory effect of cholestryamine on the rate of
excretion of chlordecone in the stool.
Source: Conn: et al. Reprinted, with permission, from the New England
Journal of Medicine, (c) The Massachusetts Medical Society (1978).
The decrease in blood Kepone levels was accompanied by a decrease in
the severity of neurologic symptoms in many of the patients. At the
outset of observation, 11 of 22 patients were unable to work due to the
severity of their neurological disorders whereas after completion of the
clinical trial, only three remained severely impaired.
Sterility or extreme depression in sperm count is another toxic
response to Kepone. Interestingly, most of the patients showed
improvement in this symptom. Motile sperm counts increased in 12 of 13
patients as blood Kepone levels declined.
The study also provided some preliminary evidence that there may be
some biotransformation of Kepone, possibly occurring in the liver or
intestine. Cohn, et al., (1978) reported the finding of an unspecified
chlordecone alcohol in the human stool. This alcohol is present in the
stool in concentrations equal or greate than chlordecone (Kepone).
6.4.3 Risk Assessment of Carcinogenic Effects
The EPA Carcinogen Assessment Group headed by E. L. Anderson has
performed a risk extrapolation for the possible carcinogenic effects of
allowing existing stocks of Kepone to be used up (U.S.Environmental
Protection Agency, 1976c). Only a linear extrapolation was possible with
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the limited exposure data available. Use of nonlinear extrapolation
methods requires knowledge not only of average exposure but also of the
distribution around the average. This is a particular problem in the
present case where accidental ingestion by children may be a significant
portion of total human Kepone exposure. The risk assessment group has
derived an average daily exposure to Kepone expressed as ppm in the diet,
taking into consideration the following factors: (1) the number of people
exposed to Kepone through the use of existing stocks, (2) the number of
years necessary to use up existing stocks (estimated at 3 years), and (3)
the proportion of the Kepone stocks which will eventually result in human
exposure. Existing total stocks then on hand were estimated by EPA at
537.8 Ib (U.S. Environmental Protection Agency, 19?6c).
The risk assessment group derived the slope of the dose response
curve from NCI data for male mice fed 23 ppm of Kepone (the case which
yields the highest results). The probability of an individual developing
a tumor due to exposure at the calculated Kepone dose was derived under
the one-hit theory of carcinogenesis. This calculation assumes that the
effect of exposure to Kepone would be the same if the same dose were
taken in a single accidental ingestion or over a period of several years.
While this assumption is consistent with the one-hit theory, it may not
be true in fact. The calculation does not take into account the special
circumstance that exposure of small children to Kepone may be greater
than exposure of other age groups. This could affect the results in two
ways. First, small children may be more or less susceptible than other
groups. Second, competing risks (the probability that a cancer is
initiated, but death from another cause intervenes before it is expressed
as a tumor) would be much smaller.
Because of the lack of firm exposure data, three different assumptions
were made. First, the highest risk to a single individual from the worst
reasonably possible exposure was estimated by assuming that a child would
eat six 3-oz tubes of ant paste over 3 years. This would result in a
cancer risk of 1/400, extrapolating from the animal data. The number of
children exposed at this level, if any, is likely to be very small.
Second, using data from Pesticide Episode Reporting System as a starting
point, it was assumed that 3,750 children might each eat about half an
ant trap containing Kepone. This would result an expected 0.083 cases of
cancer or a probability of 1/12 of one case of cancer. Finally, an
attempt was made to estimate parametrically the effects of all routes of
exposure, including vaporization, spilling onto kitchen surfaces, etc.,
in addition to accidental ingestion by children. Using a linear
no-threshold extrapolation, the resulting number of cases of cancer would
be 540 multiplied by the proportion of the Kepone which reaches humans.
An estimate of probability (P) is needed to arrive at a final
projection. For example, if it is estimated that 1/10 of 1 percent of the
total stocks would ultimately reach people (P = 0.001), then about half a
case of cancer would be projected to result (U.S. Environmental
169
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Protection Agency, 1976c). Unfortunately, no similar risk extrapolations
have been based upon the probable Kepone exposure levels and dosage
received by workers at the Life Sciences Products Company.
6.4.4 Subacute Exposure to Kepone
Allegations of former employees of LSPC that substantial amounts of
Kepone had been discharged into the sewage system prompted a request from
the Virginia State Health Department for assistance in assessing
environmental contamination (U.S. Environmental Protection Agency,
1975b). A systematic community survey was begun by EPA's Health Effects
Research Laboratory (HERD in August, 1975, to ascertain whether human
exposures (as reflected by blood Kepone levels) had occurred and if so,
to attempt to define the geographic limits of the exposure area.
Concentric circles with radii equivalent to 400, 800, 1200, and 1600
meters (1/4, 1/2, 3/4, and 1 mile) were mapped around LSPC. The area
within 400 meters was primarily commercial except for a small,
predominantly black residential area south of the plant and a high-rise
apartment building to the north occupied mostly by elderly whites. Every
fifth occupied residence was chosen systematically in the innermost areas
while on the outer three circles, a randomly selected single unit
dwelling was selected from each residential block intersecting the circle.
All occupants in each selected residence were invited to
participate. A standardized questionnaire was administered including
information on age, race, sex, self-reported neurologic symptomatology,
and residential and occupational history of each occupant. In all, 93
housesholds were sampled yielding a total of 216 participants. A venous
blood sample was drawn from each participant and a sebum sample was
obtained by wiping the forehead with a 5 x 5 cm gauze pad soaked with
acetone. Each blood extract was first analyzed by electron-capture gas
liquid chromatography (GC) at a quantitative screening level of 1 ppb.
At Kepone levels below 5 ppb, a quantitative value could not be
assigned with any degree of confidence. Therefore, the lower limit of
reporting was set at 5 ppb, with samples below 5 ppb being reported as
"nondetectable". Samples containing over 5 ppb were analyzed on both of
the GC columns used, with selected samples subjected to further
quantitative confirmation by GC.
Of the 216 blood samples analyzed, 40 (approximately 19 percent)
contained 5 to 50 ppb Kepone. The remaining 176 samples contained
nondetectable levels ( 5 ppb) of Kepone. Thirty-four of these 40
samples were from the residential area within 400 meters south of LSPC.
Two additional detectable samples were from the apartment building to the
north of LSPC, and the remaining four were from participants residing 800
meters or more from the plant.
170
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Percentages of blood samples above the detectable level were:
39 percent (34/87) in the residential area south of LSPC
7.7 percent (2/26) in the apartment to the north
5.9 percent (2/24) 800 meters away
2.6 percent (1/39) 1200 meters away
3.3 percent (1/30) 1600 meters away.
None of the people reported having worked at either LSPC or at the Allied
Chemical Corp. semiworks where Kepone had been manufactured prior to 1974.
Within the most exposed area there was marked bimodality, according
to age, in the proportion of persons with detectable blood levels,
reaching a peak in pre-teen age children and in older adults. A marked
depression was observed in the intermediate age groups. None of the
analyzed blood samples collected from the general population contained
greater than 50 ppb of Kepone. These blood levels of Kepone are
substantially lower than those found in LSPC employees. Nevertheless,
they should be viewed as evidence of environmental contamination.
Human sebum samples which were collected from hospitalized workers
from the Kepone manufacturing plant contained 0.2 to 3 microgram of
Kepone whereas there was no detctable Kepone in samples from the general
population (U.S. Environmental Protection Agency, 1975b). Sebum from some
of the non hospitalized workers contained 0.05 to 0.8 microgram of Kepone.
Although these data are of diagnostic value, they merely suggest
exposure routes. Little information is provided about the extent and
duration of exposure, and nothing about the distribution and accumulation
in target organs and tissues or metabolism or elimination of this
compound can be determined on the basis of these findings. Lack of
24-hour urine samples and of fat biopsies or adipose tissue samples
collected simultaneously with the blood samples during the exposure
period precludes estimates of average daily doses or intake of Kepone.
Owing to the lack of data relating blood levels and manifestation of
adverse clinical or pathological effects, interpretation of the
significance of blood levels in the 5 to 50 ppb range must be deferred.
Similarly, human data on dose-response to Kepone must await the
completion of the studies of Life Sciences Products Co. workers.
6.5 RESIDUES IN FOODS
6.5.1 Mirex
The established tolerances for mirex are 0.1 ppm (negligible
residue) in the fat of meat of cattle, goats, hogs, horses, poultry, and
sheep; 0.1 ppm (negligible residue) in milk fat and eggs; and 0.01 ppm
(negligible residue) in or on all other raw agricultural commodities
(U.S. Environmental Protection Agency, 1976d).
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Because mirex is a very stable insecticide capable of being stored
in fat, the U.S. Department of Agriculture conducted a survey to
determine (1) whether cattle grazing on treated pastures would accumulate
mirex in their tissues, and (2) the environmental distribution of mirex
following application (Ford, et al., 1973). Samples of fat from beef
cattle were obtained from two areas of Mississippi and Georgia heavily
infested with fire ants, which were known from USDA records to have
received blanket applicationsn of mirex at least twice in the past 3
years. State meat inspectors collected 1000 g samples of subcutaneous fat
from five different locations on the carcasses. Limited samples of
internal organs were also obtained. Similar samples were also obtained
from cattle in control areas outside the region where mirex had been
used. Analysis was performed by gas-liquid chromatography using a
modification of the Armour-Burke method (Armour and Burke, 1970) to
remove interference from PCB's. Residues of mirex were found in 88
percent of the samples, with levels ranging from 0.001 to 0.125 ppm and
an average value of 0.026 ppm. Only one sample, 0.125 ppm, was in excess
of the established tolerance level of 0.1 ppm for mirex in the fat of
beef cattle. No residues were found in the other organs (Ford, et al.,
1973).
Because mirex has been used as flame retardant under the name
Dechlorane, samples from untreated areas in both the southeast and in
other areas were obtained. The absence of mirex in samples from untreated
areas, strongly indicates that residues found in samples from the treated
areas were from the insecticide application. The authors concluded that
residues can be expected in beef fat in treated areas following the use
of mirex, but that application in the prescribed manner will keep
residues below the tolerance level.
In obtaining a registration and tolerance level for mirex, Allied
Chemical Corporation monitored whole milk and milk fat for mirex in a
herd of cows grazing on a pasture treated with a single application of
bait. They reported 0.002 to 0.007 ppm in whole milk and 0.02 to 0.13 in
milk fat (Hawthorne, et al., 197*0. (Presently there is a tolerance level
of 0.01 ppm for whole milk and 0.1 ppm for milk fat).
Since the same residue levels were found in pretreatment and
untreated control animals, Hawthorne, et al., doubted the validity of
findings from the Allied Chemical study and initiated another milk
survey. Inspectors familiar with dairy farms and processing plants in
southeastern U.S. selected areas which had received two or more mirex
treatments. After verifying that all the milk had come from cows that had
grazed in the treated areas, a 1-quart sample of milk was taken from the
storage tanks of each dairy or processing plant. Ten or more samples were
taken from different locations in the following states: Florida, Georgia,
Louisiana, Mississippi, and South Carolina. Samples were analyzed by gas
chromatography with an estimated limit of detection of 0.3 ppb-
A total of 66 samples were obtained from the five states, including
6 control samples obtained from untreated areas. The remainder of the
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samples were from areas which had been treated 2 to 5 times. Of the 60
samples analyzed, none had detectable mirex residues at the 0.30 ppb
level of detection; however, at least 26 of the samples were from areas
which had received their last mirex treatment 1 year or more prior to
collection. Another 26 of the samples were from areas which had been
treated at least 6 months before sampling. Many samples contained small
but questionable peaks at the same retention time as mirex; however,
attempts to confirm these peaks by thin-layer chromatography (TLC), and
fortifying and using additional columns, were inconclusive. The authors
conclude that milk cattle must be receiving some small amounts of mirex,
but not enough to show up in milk at the detection level of about 0.3
ppb. Mirex might also be better detected if the samples were taken closer
to the time of treatment. Thus, milk from cattle in treated areas may
contain minute quantities of mirex; but the amounts are at least 100
times lower than the presently established levels for milk (Hawthorne, et
al.f 1974).
Lane (1973) investigated the possible uses of food processing to
degrade pesticidal residues in foods. Tissue samples (crawfish) and eggs
(mallard ducks) contaminated with mirex were processed by (1) a
commercial thermal processing procedure, (2) drastic heat treatment and
(3) irradiation with ultraviolet light. Mirex residues from tissue
samples processed by each of the three methods did not differ
significantly from controls. Photolysis and gamma irradiation of eggs,
however, demonstrated a highly significant difference among the mean
residue content of controls and the means at various time intervals as
irradiation proceeded. A linear relationship was seen between mirex
degradation and increasing radiation dosage. Monohydro and dihydro
degradation products of mirex were separated and identified by combined
flame ionization gas chromatography-mass spectrometry and retention time
data (see Section 2.3.2.1.).
In 1968-1969 the U.S. Department of Agriculture (USDA) conducted a
study on Cat Island off the coast of Mississippi and in 1969-1970 the
USDA and the U.S. Department of the Interior cooperated in a similar
study. Both studies showed mirex residues ranging from 0.001 to 2 ppm in
some bottom feeding fish immediately following a mirex treatment. Small
amounts of residues could be detected as much as 2 years later (Markin,
et al. , 1971). Other studies have discovered mirex residues in commercial
catches for human consumption well outside the immediate treatment area.
In August, 1975, the Food and Drug Administration (FDA) as part of
its routine pesticide surveillance activities, first learned that mirex
was a chemical contaminant of Lake Ontario. EPA's Duluth Laboratories had
reportedly found mirex residues in Lake Ontario several years earlier;
however, FDA was not informed of these findings (Wessell, 1976, personal
communication). From August to November, 1975, FDA laboratories analyzed
18 samples of fish representing 10 species taken from different parts of
Lake Ontario (U.S. Department of Health, Education, and Welfare, 1976).
As indicated in Table 6.6 all but two of the samples were found to
contain mirex residues ranging from trace (less than 0.03 ppm) to 0.53
173
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TABLE 6. 6. PESTICIDE RESIDUES IN LAKE ONTARIO FISH COLLECTED IN AUGUST AND SEPTEMBER, 1975*
Residue , pom
Lake Ontario Source
Chnumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
H Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Chaumont Bay
Salmon River Outlet
Pulaski, N.Y.
Galloo Island area
Unknown Source
Unknown Source
Specie
Bullhead
Bullhead
Bullhead
Rock Bass
Smallmouth
Black Bass
Smallmouth
Black Bass
Northern Pike
Northern Pike
Northern Pike
Northern Pike
White Perch
White Perch
Yellow Perch
Herring b
(Mooney)
Coho Salmon
White Perch
Lake Trout
Weak Fish
Mirex
T
0.03
0.04
T
0.19
T
0.08
0.06
0.06
0.04
0.05
0.12
—
—
0.35
T
0.53
T
PCB
Aroclor 1254
0.39
0.50
0.75
0.55
2.69
1.15
1.60
1.29
1.09
0.96
1.00
2.94
0.43
0.99
10.75
2.33
14.62
0.57
PCB
Aroclor 1248 DDE
0.03
0.04
0.05
0.02
0.48
0.09
0.18
0.18
0.13
0.13
0.19
0.43 0.42
0.04
0.16
1.11
0.54 0.32
0.96
—
DDT TDE
0.01
0.01
0.02
T
0.10 0.07
..
..
_.
_.
—
0.06 0.06
0.25
x
•»«• *£
0.22 0.25
T 0.13
0.25 0.34
..
Dieldrin
T
T
T
—
0.01
T
—
—
—
—
0.19
0.04
T
0.02
0.10
0.06
0.24
~
BHC
T
T
T
T
T
T
0.01
—
0.01
*•*•
T
..
T
~
0.15
T
0.29
—
Source: Food and Drug Administration, (1976).
^Herring sample collected by FDA; all others collected by New York State.
T - trace.
-------
ppm. The samples contained not only mirex but also varying combinations
of PCB's (primarily Aroclor 1254) dieldrin, BHC, and DDT-related
compounds, The accuracy of these results has been questioned because
mirex was not separated from the PCB's prior to determination by electron
capture gas chromatography. Also, PCB (especially Aroclor 1254) was
overwhelmingly the highest residue in all samples. Since PCB has a late
eluting GC peak which closesly resembles that of mirex, improper
identification could result in serious errors in mirex residue
calculations. Nevertheless, the authors conclude that the mirex residues
reported probably do not represent spurious findings due to analytical
errors because mirex residues have been confirmed in fish and fish eating
birds (herring gulls) and their eggs in Lake Ontario (Kaiser, 1974;
Canadian Ministry of the Environment, 1976; Alexander, personal
communication, 1976).
As a result of the above findings, FDA requested and received from
EPA's Office of Pesticide Programs a recommended action level of 0.1 ppm
for mirex residues in fish. This action level was put into effect May 18,
1976.
Table 6.7 presents some recent mirex findings for fish in Lake
Ontario and tributaries (New York State Department of Environmental
Conservation, 1976). From the large reservoir of fish data presented in
Table 6.7 it can be seen that a significant number of species of fish
exceed the present FDA standard of 0.1 ppm. These can be summarized as
follows:
Classes of fish consistently exceeding 0.1 ppm mirex
o Salmon!dae (trouts)*
o Osmeridae (smelts).
Classes of fish consistently below 0.1 ppm mirex
o Esocidae (pikes)
o Cyprinidae (minnows and carps)
o Catostomidae (suckers)
o Pecidae (perches).
Classes of fish with mirex concentrations varying above and below 0.1 ppm
o Percichthyidae (temperature basses)**
o Ictaluridae (freshwater catfishes)
o Centrarchidae (sunfishes)***
o Anguillidae (freshwater eels)
o Clupeidae (herrings)
* Except for rainbow trout
** Tended to exceed or approach 0.1 ppm except for wall eye
*** Tends to be below 0.1 ppm for smallmouth bass
175
-------
TABLE 6. 7. MIREX DATA FOR FISH FROM LAKE ONTARIO AMD TRIBUTARIES,
AS OF SEPTEMBER 22, 1976*
Fish
Species
White Perch
Lake Trout
Catfish
Coho Salmon
Brown Trout
Rainbow Smelt
American Eel
Alewlfe
Chinook Salmon
Smallmouth Bass
Coho Salmon
Brown Trout
White Perch
Brown Bullhead
White Perch
Yellow Perch
White Bass
Northern Pike
Northern Pike
American Eel
Walleye
Rainbow Trout
Carp
Northern Pike
Suckers
Brown Bullhead
Black Crappy
Yellow Perch
Largemouth Bass
Rock Bass
Bluegill
Chain Pickerel
Gizzard Shad
Minnows
Yellow Perch
Family"
P
S
I
S
S
0
A
H
S
C
S
S
P
I
P
PR
P
E
E
A
P
S
CY
E
CA
1
C
PR
C
C
C
E
H
CY
PR
Location0
NS
SS
NS
NS
NS
NS
NS
NS
SS
SS
SS
SS
SS
NS
CB
NS
NS
SS
CB
SS
SS
NS
NS
NS
NS
CB
NS
SS
NS
CB
NS
NS
NS
NS
CB
Number
Analyzed
3
2
3
79
10
206
4
13
1
10
1
12
4
83
8
80
12
2
11
1
2
60
4
11
50
10
3
11
3
10
10
2
3
2
8
Number
of
Analyses
3
2
3
79
10
50
4
1
1
10
1
12
4
83
2
80
12
2
4
1
2
60
4
11
50
2
3
6
3
1
10
2
3
NR
1
Mean
Mirex Total PCB
Concentrations ,ppm Concentration,
Mean
0.38
0.35
0.27
0.23
0.22
0.18
0.16
0.15
0.13
0.13
0.12
0.11
0.11
0.09
0.09
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.02
0.02
0.02
0.01
0.01
0.004
Trace
ND
ND
ND
ND
ND
Range
0.25-0.50
0.28-0.42
0. -0-0. 38
0.04-0.40
0.15-0.35
0.02-0.20
0.12-0.22
—
—
0.03-0.27
—
0.03-0.22
0.07-0.18
ND-0.80
0.05-0.12
ND-1.3
0.04-0.13
0.04-0.09
0.06-0.08
—
0.03-0.05
0.005
0.01-0.05
ND-0.10
ND-008
Trace-0.04
0.008-0.02
Trace-0.04
0.004-0.005
—
—
—
—
—
—
ppm
NR
17.4
NR
NR
NR
NR
NR
NR
9.13
5.42
9.22
6.54
7.51
NR
1.72
NR
NR
2.91
1.04
1.00
3.24
NR
NR
NR
NR
0.57
NR
1.69
NR
0.55
NR
NR
NR
NR
0.43
Footnotes on next page.
176
-------
FOOTNOTES FOR TABLE 6.7
aSource: New York State Department of Environmental Conservation, (1976).
P Percichthyidae (temperate basses)
S Salmonidae (trouts)
I Ictaluridae (freshwater catfishes)
0 Osmeridae (smelts)
A Anguillidae (freshwater eels)
H Clupeidae (herrings)
C Centrarchidae (sunfishes)
PR Percidae (perches)
E Esocidae (pikes)
CA Catostomidae (suckers)
CY Cyprinidae (minnows and carps).
CNS Canada/North Shore—Various locations
SS U.S./South Shore—Various locations
CB Chaumont Bay.
Not reported
177
-------
Interestingly, fish with high mirex concentrations have also high PCB
concentrations.
Mirex (and Kepone) are monitored in South Atlantic and Gulf Coast
states as part of FDA's Compliance Program Evaluation (U.S. Department of
Health, Education, and Welfare, 1977). Table 6.8 displays mirex levels in
the 132 samples examined. The findings are grouped by State and further
by specie group (finfish, shellfish, crustaceans) within each state. It
can be seen that none of the surveys of shellfish and crustaceans showed
detectable mirex (Alabama, Louisiana, Georgia, including Northeast
Florida, Mississippi, and South Carolina). In the case of finfish,
however, all surveys except the Texas survey contained some samples with
detectable mirex (Alabamam, Arkansas, Louisiana, and Mississippi). The
average mirex levels for finfish in the complete surveys within these
states were:
• Alabama (0.029 ppm)
• Arkansas (0.021 ppm)
• Louisiana (0.015 ppm)
• Mississippi (0.002 ppm).
Further breakdown of the surveys relative to the geographic area within
each state shows some variation in the levels in finfish from different
areas within the respective state. For example, in Arkansas the 9 samples
from the central area were all negative for mirex and the 2 positive
identifications both came from southern Arkansas. This analysis of
findings indicates a relationship between mirex-treated areas (1976) and
positive survey findings. Shell fish and crustaceans do not appear to
support this general observation since all were negative in Southern
Louisiana and Mississippi where mirex was applied in 1976.
One factor studied in this survey was the possible co-occurrence of
Kepone and mirex in fish resulting from environmental or metabolic
conversion of mirex (from mirex bait) to Kepone. This relationship was
not observed in this survey since only one sample of crabs from Georgia
was found to contain Kepone (trace level) and it contained no detectable
mirex. Mirex was found in numerous finfish samples, with no detectable
Kepone.
Data on mirex residue accumulation in selected items of the human
food chain were also monitored in an extensive study of vertebrates by
Collins, et al., (1974). These data are presented in Section 7.
6.5.2 Kepone
The problem of Kepone contamination of fish goes beyond Virginia
waters. Kepone has been discovered in fish along the Atlantic Coast from
Delaware to North Carolina. In early 1976, FDA established regulatory
action levels for unavoidable residues of Kepone in fishery products.
These levels, based on recommendations from the Environmental Protection
Agency, are as follows:
178
-------
TABLE 6.8. MIREX FINDINGS BY GEOGRAPHIC AREAS WITHIN
SOUTH ATLANTIC AND GULF COAST STATES3
State
Fin Fish
Shellfish
Crustacea.
Number of Mean ppm Survey Number of Mean ppm Number of Mean ppm
Location Samples Mirex Mean Samples Mirex Samples Mirex
Alabama
Arkansas
Florida
Georgia
Louisiana
Mississippi
South Carolina
Texas
Northern
Southern
Eastern
Southern
Central
Northern
Eastern
Northern
Southern
Central
Southern
Central
Eastern
Northern
Southern
8
4
3
9
1
11
12
6
6
.035 -i
.018
.083
N.D.
.022
.014
.002
t
N.D. |
N.D. J
.029
.021
.015
.002
N.D.
12
N.D.
12
N.D.
1 N.D. one
11 N.D. survey
12 N.D.
12 N.D.
12 N.D.
Adapted from U.S. Department of Health, Education and Welfare (1977).
ND - Non detected.
-------
Kepone in oysters, clams and 0.3 ppm
mussels (edible portion)
Kepone in finfish (edible
portion) 0.1 ppm
Kepone in crabs (edible portion) 0.4 ppm
Currently, these action levels are being enforced, although there is
a great deal of agitation by fishermen and other commercially interested
parties for an upward revision of these concentrations. Several meetings
have been held to discuss this possibility and presently EPA has
responded to this request by recommending to FDA that the permissible
amount of Kepone in finfish be raised from 0.1 ppm to 0.3 ppm (Anon.,
1977).
Kepone has been found in fresh water trout and suckers taken from
Spring Creek which runs near the Nease Chemical Plant in State College,
Pennsylvania. That plant produced Kepone in 1958-59 and 1963, and
produced mirex, which can be converted to Kepone, as late as 1974. Trout
contained Kepone in amounts ranging from 0.15 to 0.17 ppm and suckers had
Kepone levels as high as 0.18 ppm (Anon., 1976d). Federal standard for
human consumption is 0.1 ppm. Pennsylvania officials are presently
conducting an extensive survey of fish and waters in the area; however,
results are not yet available.
Currently, the FDA Market Basket Program does not monitor foods for
Kepone residues, but the FDA is conducting a survey of Kepone residue
levels in Chesapeake Bay and East Coast fish. Upon finding traces of
Kepone in fish sold in Baltimore, Norfolk, Philadelphia, and New York,
and in fish caught off New Jersey and Long Island, FDA announced that it
will broaden its monitoring program for fish sold in East Coast cities
and for fish, shellfish and crustaceans caught on the East Coast.
Unacceptable levels of Kepone were found only in fish sold in Baltimore
and Norfolk. (Anon., 1976e).
While the majority of shellfish taken from the James River contain
less than the 0.3 ppm action level of Kepone, oyster and clam samples
taken from the fall line at Richmond to Hampton Roads contained 0.21 to
0.81 ppm of Kepone. Samples of crabs from Hampton Roads and the Elizabeth
River contained 0.45 to 3.44 ppm Kepone. Fish and fish parts samples from
the Hopewell, Virginia, area contained from 0.02 to 14.4 ppm of Kepone
(Shanholtz, 1976). The observations of high Kepone levels in fish,
shellfish, and crabs from the Hopewell, Virginia, area together with the
findings of similarly high levels in Baileys Creek (1 to 4 ppb),
Appomattox River (greater than 0.1 ppb), James River (0.11 to 0.28 ppb),
and 1 to 4 ppm in sediments from the same three locations, prompted a ban
on taking fish, shellfish, and crabs from the James River and its
tributaries from Richmond to the Chesapeake Bay. The order became
effective December 17, 1975 (Shanholtz, 1976).
180
-------
FDA's findings of excessive levels of mirex and Kepone in Lake
Ontario fish caused the State of New York to ban the possession of six
species of Lake Ontario fish, including: coho and Chinook salmon, brown
bullhead, catfish, lake trout, small mouth bass, and alewife herring.
Limited consumption of white perch, white bass and smelt was also advised
(Whalen, 1976 personal communication; Anon., 19?6f). FDA's Buffalo
District Office has been working closely with the State of New York in
monitoring Lake Ontario fish for mirex and other chemical residues.
Because Kepone may be present as an impurity in mirex formulations and
mirex can under certain conditions be converted to Kepone, FDA has
instructed its district offices located in states where mirex has had
extensive use to test commercial fishery products for both mirex and
Kepone residues. In view of the proximity to Hooker Chemmical's Niagara
Falls plant which produced mirex, FDA's Buffalo District also includes
analyses for Kepone residues in Lake Ontario fish samples that are
collected under its cooperative program with the State of New York
(Wessel, 1976 personal communication).
The data presented below represent recent findings of the FDA
Compliance Program Evaluation as of the December 2, 1976, reporting
period (Corneliussen, 1976 personal communication). Cumulative Kepone
totals are reported in groups according to species and location:
(1) Official Sampling Originating from the Chesapeake Bay
Five additional samples were reported during the November
18 to December 2, 1976, period. This brings the cumulative
average level of Kepone to 0.037 ppm for 75 finfish, 0.61
for 11 samples of crabs, and no detected Kepone in 3 samples
of oysters and one sample of clams.
The cumulative number of each species examined followed by
the average ppm Kepone for that specie are as follows: 21
croaker (0.032 ppm), 21 bluefish (0.046 ppm), 13 trout
(0.043 ppm), 8 spot (0.022 ppm), 4 catfish (0.023 ppm), 1
rockfish (none detected), 2 mackerel (0.075 ppm), 3 flounder
(0.01 ppm), 2 butterfish (0.05 ppm), 11 crabs (0.061 ppm),
3 oysters (no detectable Kepone), and 1 clam (no detectable
Kepone).
(2) Bluefish Caught in the Atlantic Ocean
No additional samples were reported during the past sampling
period. Therefore, the total remains at 62 samples under
this program. Of this total, Kepone was not detected in 10
Florida samples and 2 North Carolina samples; Kepone levels
from traces to 0.03 ppm were found in 42 samples from North
Carolina, Delaware, New Jersey, New York, Rhode Island, and
Massachusetts; and 8 samples from the Virginia Atlantic Coast
contained Kepone in the 0.01 to 0.06 ppm range.
181
-------
(3) Kepone/Mirex Survey Samples from South Atlantic and Gulf
Coast Areas:
Twenty-four (24) additional samples were reported during the
past sampling period, bringing the cumulative sample total
under this program to 48 finfish, 28 shrimp, 20 crab samples,
and 21 oyster samples from Texas, Louisiana, Georgia,
Florida, South Carolina, Mississippi, Arkansas, and Alabama.
Of these, only one sample of crabs from Georgia contained a
trace of Kepone. Mirex findings from the South Atlantic and
Gulf Coast areas are reported in Section 6.5.1.
EPA has recommended to the Food and Drug Administration (FDA) the
following "action levels" (allowable temporary levels of pesticide
residues to be used as enforcement guides): 0.3 ppm of Kepone in the
edible portion of shellfish (oysters and clams), 0.1 ppm in finfish, and
0.4 ppm in crabs. EPA has also recommended a 0.03 ppm action level in
processed oyster stew.
An action level is permitted under existing regulations when a food
or feed commodity is inadvertently contaminated. Action levels are set on
the basis of two primary factors: (1) the level of actual residues found
in the affected commodity and (2) the safety of that level to humans
based upon probable exposure and extrapolation from toxicological data
showing that no greater levels could safely be tolerated in the human
diet (Blanchard, 1976).
The action levels considered dietary intake of the commodities
carrying the residues. Oysters are only 0.23 percent of man's diet on the
average and at the action level of contaminatin would contribute less
than one millionth of a gram of Kepone per week. Crabs make up even less,
0.16 percent of man's diet, which is the reason for the higher action
level. Finfish make up a larger portion, 0.72 percent, which explains the
considerably lower action level recommendation.
Under usual action level procedures, the highest amount of a toxic
chemical found not to cause chronic toxic effects in test animals is
established; this is then reduced by a factor of 1/100. However, for
Kepone, the EPA used a safety factor of at least 1/1,000 because of the
extent of public concern with Kepone contamination (Blanchard, 1976).
Control of the banana root borer constitutes the only food or feed
use of Kepone. Although the Kepone is applied to the ground and not to
the plant, there is some possibility of contamination of the fruit.
Originally, EPA regulations allowed a tolerance of 0.01 ppm of Kepone in
or on the fruit (40 CFR 180.287). This tolerance for bananas was
considered safe on the basis of essentially no residue in the edible
pulp, rather than on supportive toxicological data (U.S. Environmental
Protection Agency, 1975a). Residues up to the level of the established
tolerance were presumed to be present on the skins but residues, if any,
182
-------
In the edible pulp of the bananas were presumed, on the basis of the
evidence submitted with the registration petition, to be less than the
sensitivity of the analytical method (GC), estimated at 0.005 ppm. This
tolerance was revoked, effective January 27, 1978 (U.S. Environmental
Protection Agency, 1978).
Kepone has also been used to control wireworms in tobacco fields.
The persistence of Kepone in soils suggests the possibility of carry over
of Kepone residues to food crops grown in rotation with Kepone treated
tobacco. EPA reports that no studies addressing this topic have been
located (U.S. Environmental Protection Agency, 1975a).
183
-------
6.6 REFERENCES
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Chicago, Illinois, October 13, 1976.
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Suta, B. E. 1977- Human Population Exposure to Mirex and Kepone.
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Original tables dated 4/21/72 (2 pp) and revised tables dated
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17 pp plus attachments and tables.
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Pesticide Programs, Criteria and Evaluation Division. Unpublished
report. 24 pp.
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Kepone Levels Found in Environmental Samples from the Hopewell,
Virginia, Area. Health Effects Research Laboratory, Research
Triangle Park, North Carolina. Unpublished report. 33 pp.
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Kepone Levels Found in Human Blood from the General Population of
Hopewell, Va. Health Effects Research Laboratory, Research
Triangle Park, North Carolina. Unpublished. 16 pp.
U.S. Environmental Protection Agency. 1976b. CRPAR Checklist - Active
Ingredient Chlordecone (Kepone). Unpublished internal working
document. 15 pp.
U.S. Environmental Protection Agency. 1976c. Analysis of Kepone. The
Carcinogen Assessment Group. Unpublished. 18 pp.
U.S. Environmental Protection Agency. 1976d. Code of Federal
Regulations. 1976. Title 40, Protection of the Environment. Sec.
180.251. Tolerances for Residues (Kepone).
U.S. Environmental Protection Agency. 1978. Revocation of Tolerance for
Kepone. Federal Register 43(19) 3708-3709. January 27-
186
-------
Wessel, John R. 1976. U.S. Dept. of Health, Education and Welfare,
Public Health Service, Food and Drug Administration, Washington,
D.C. Personal communication with Oilman D. Veith, U.S.
Environmental Protection Agency, Duluth, Minnesota. August 311
1976.
Whalen, R. P. 1976. Personal communication. Memo on New York State
Banning of Specific Lake Ontario Fish. Robert P. Whalen, M.D.,
Commissioner of Health, State of New York. 4 pp.
Yobs, A. R. 1971. The National Human Monitoring Program for Pesticides.
Pesticides Monitoring J. 5(1): 44-46.
187
-------
7.0 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
7-1 SUMMARY
The principal route of entry of mirex into the environment has been
the aerial application of mirex bait, applied to millions of hectares in
the southeastern United States for fire ant control. Residues of mirex in
the U.S. environment are at low levels, frequently approaching the limit
of detection. This is consistent with the rate of application which has
been utilized for fire ant control, normally 4.2 g/ha (1.7 g/ac), and the
total cumulative application of probably less than 250,000 kg (550,000
Ib) during the 1962 - 1975 period (see Section 2.5.1.2). Theoretical
concentration in the top 7.5 cm (3 in) of soil at recommended rates of
application would, assuming no removal by fire ants, be 4 to 5 ppb;
experimental soil analyses bracket this value, most are below this.
Less generally recognized is the potential contribution to
environmental contamination of mirex (C^Cl^) marketed as a fire
retardant additive for polymeric materials under the name Dechlorane. The
contamination in Lake Ontario is partially from wastes from
mirex-Dechlorane manufacture, and partially from a Dechlorane spill, and
is not from any insecticidal application of mirex. Sediment analyses
indicate that several hundred kilograms of Dechlorane (mirex) are trapped
in lake sediments nearest the two discharge points.
The measured solubility of mirex in water is 1 ppb or below, and
mirex in natural waters is frequently undetectable at a 0.01 ppb
sensitivity. Experimentally, water concentrations of 1 to 10 ppt have
been detected in regions treated for fire ant control. Concentrations in
sediments are higher, typically by a factor of 10 to 20.
All evidence points toward a high degree of stability for mirex in
the environment, whether in soil or sediment. It has been suggested that
the half-life may be 12 years (or more); this is supported by
experimental field determinations of mirex in soil and sediment which had
been exposed for such a period. Kepone, incidentally, appears to be a
major intermediate degradation product of mirex.
Kepone has no significant agricultural uses in the U.S. The
principal route of entry of Kepone to the U.S. environment, unlike mirex,
has not been the result of its insecticidal application but the result of
waste discharges and losses during its manufacture at Hopewell, Virginia.
The amount of Kepone which has escaped from its principal U.S. use in ant
and roach traps appears to be virtually undetectable.
188
-------
Prior to the Life Science Products Company incident, essentially no
data existed on environmental concentrations of Kepone. In connection
with the investigation of that incident, hundreds of analyses have been
performed on air, water, soils, sediments, and biota from the area in and
around Hopewell, and from the James River and Chesapeake Bay.
Contamination of James River sediments by Kepone from Hopewell nearly to
Newport News has been demonstrated. It has been estimated that as much as
45,000 kg of Kepone may lie on the bottom of the James River. The
mobility of this Kepone is anticipated to depend on the mobility of the
sediments. Since Kepone, like mirex, is resistant to biodegradation, this
inventory will pose a problem for many years.
Field studies have shown that mirex tends to bioconcentrate in some
species, especially in predaceous species. Although the residue levels
found generally appear to be below those causing acute toxicity, the
long-range effects of low chronic dosages are conjectural.
7.2 DISTRIBUTION OF MIREX IN THE
PHYSICAL ENVIRONMENT
7.2.1 Entry Into the Environment
The principal route for the entry of mirex into the environment has
been the aerial application of mirex bait, used in the southeastern
states for fire ant control. Areas treated and annual quantities are
shown by Table 2.4. As noted in Section 2.5.1.2, the total quantity of
mirex applied between 1962 and 1975 may have approached 250,000 kg
(550,000 Ib). Theoretically, all of this was applied to land. However,
the precision of aerial application with the fixed wing planes employed
was not such that spill over to aquatic areas can be ruled out. It seems
quite likely that some mirex was inadvertently applied over water. In
recent years helicopters and small aircraft have been used; precision of
application appears to be good with these methods.
The role of Dechlorane in the contamination of the environment by
C10C11,) (mirex) should not be overlooked. Most of these identical
chemicaf compounds produced between 1959 and 1967 were manufactured at
the Hooker Chemical plant at Niagara Falls, New York. Aqueous wastes from
this plant were discharged either into the Niagara River or into the
Niagara Falls sanitary waste system, whose effluent was also discharged
into the Niagara River. The Niagara River empties into Lake Ontario, in
which C1QC112 (Dechlorane-mirex) contamination has been found, as
described in a later section. There appear to be no data on the
quantities of such discharges during this period.
All Dechlorane-mirex has been ground and packaged at the Hooker
Niagara Falls plant both during the period when it was manufactured there
and subsequently. Material is ground for approximately one week per year
and the grinder is washed after the week-long campaign. An analysis of
this cleanup operation in 1974 indicated that 136 liters (36 gallons) of
189
-------
aqueous waste, containing 62 ppm of C10C112, was discharged to the
Niagara Falls sanitary sewer system (Chambers, 1*976).
Results of another survey, by EPA Region II personnel in January
1975, indicated a level of 270 ppm of mirex in 125 gallons of cleanup
water resulting from the reprocessing of 1,360 kg (3,000 Ib) of mirex. A
Region II field inspector estimated in his report of the visit that, at a
minimum, Hooker discharges 9 kg (20 Ib) of mirex per year to the Niagara
Falls Sewage Treatment Plant (STP) (Legro, 1976).
Automated dust collectors, rated at 99.9 percent collection
efficiency by the manufacturer, are used for the grinding operation. No
visible discharges have been observed by Company or government personnel
(Chambers, 1976).
Subsequent to 1967, when manufacture of mirex-Dechlorane by Hooker
was terminated, the Nease Chemical Company at State College,
Pennsylvania, supplied the product, from 1968 to 1969 and again from 1973
to 7^ (see Section 2.5.1.1). No data on losses from the Nease Chemical
Company operations have been found.
Another possible source of entry of mirex-Dechlorane into the
environment is associated with the manufacture, use, and disposal of
products containing Dechlorane fire retardant additive. Unlike mirex,
essentially all of which went to the southeastern U.S., Dechlorane was
distributed to customers for a wide variety of uses (plastics,
pyrotechnics, roofing, and elastomers) at a multitude of North American
locations, including Canada. The ultimate fate of these products, which
represented three times as much C10C112 as was used for fire ant bait, is
uncertain.
7.2.2 Soil
At the standard application rate of 1.4 kg/ha (1.25 Ib/ac) of 4X
bait, approximately 4.2 g/ha (1.7 g/ac) of active ingredient was applied.
It has been calculated that this is equivalent to approximately 4 ppb
(Mirex Advisory Committee, 197^) or 5 ppb (Markin, et al., 1972) in a
standard 3-inch soil sample. Mirex concentrations in soil have been
found to be of this order of magnitude. The two laboratories most active
in monitoring efforts have been the USDA Gulfport, Mississippi,
laboratories, and the EPA laboratories at Gulf Breeze, Florida, along
with various state agencies in the southeastern U.S. Unfortunately,
results of these studies have, in general, not been published (Alley,
1973).
•At the reduced 0.45 g/ac application rate, initiated in 1977, the
corresponding average soil concentration is only 1 ppb.
190
-------
Mirex residues in soils from open pasture following normal aerial
treatments have generally ranged from 0.1 to 10 ppb. (Mirex Advisory
Committee, 1972). Markin, et al., (1972) reported that in two studies,
the residues in soils in open pastures, away from ant mounds, ranged from
0.7 to 2.5 ppb. The highest amount of mirex detected in soil was 100 ppb,
found in the soil of a recently treated ant mound and probably
represented mirex concentrated in the mound by ants.
Spence and Markin (1974) reported on the time-variant soil
concentrations for two field test plots in Louisiana and Mississippi.
Each site also contained one or more ponds so that water and sediment
concentrations were also available. Soil mirex concentrations (7.5 cm
depth) ranged from 0.2 to 2.5 ppb at the Louisiana site, and from 0.3 to
10.4 at the Mississippi site, as illustrated in Table 7.1. At the 4.2
g/ha (1.7 g/ac) rate of application, the expected residue level in the
upper 7-5 cm of soil would be about 4 ppb. In the Louisiana plot the
concentrations found immediately after treatment were much lower,
possibly indicating collection and removal by foraging fire ants. The
gradual subsequent buildup was suggested by the authors as a possible
result of excretion or decomposition of dead insects. The much greater
variability in Mississippi results was believed to be possibly due to the
winter (February) application of mirex, when insect activity was minimal;
Louisiana application had been made in May.
Johnson, et al., (1976a,b) and Bevenue, et al., (1975) described the
results of the 1972-1974 monitoring program on the treatment of pineapple
fields with mirex. 4X bait was applied at the rate of 6.2 kg/ha (2.5
Ib/ac), i.e., 8.4 g/ha (3.4 g/ac) of active ingredient, which is twice
the standard rate for fire ant control. Results of the analysis of eight
soil samples taken at varying times up to 9 months after the mirex
application are tabulated below. The first sample in each field
represented background levels 1 week prior to treatment.
Field 233 Field 234
Date Mirex, ppb Date Mirex, ppb
October 6, 1973 ND October 6, 1973 ND
November 3, 1973 3 November 2, 1973 9
January 19, 1974 4 January 19, 1974 5
April 21, 1974 ND April 21, 1974 9
July 13, 1974 ND July 13, 1974 9
ND = Not detected.
7.2.2.1 Mobility and Persistence in Soil-
Several bits of evidence point towards a long persistence of mirex
in soil. It is essentially insoluble, so that dissolution does not appear
likely to be a major mechanism for translocation. Laboratory experiments
indicated that decomposition by photolysis proceeds very slowly. As the
191
-------
TABLE 7.1 MEREX RESIDUES IN SOIL COLLECTED IN
MISSISSIPPI (1972) AND LOUISIANA
(1971-72)a
Days
Post treatment
Mississippi
Pretreatment
1-3 hours
1
2
3
7
14
21
28
35
42
49
56
63
70
77
84
91
98
105
112
Louisiana
Pretreatment
1-3 hours
3
4
7
17
25
31
38
45
54
69
77
90
117
164
185
223
268
337
374
Mi rex, ppb
—
6.3
0.71
0.31
4.2
0.87
0.41
0.22
1.2
1.3
4.0
0.78
2.7
8.2
1.5
1.2
2.0
10.4
2.4
1.1
0.31
—
0.70
0.70
0.30
0.80
0.70
2.0
2.0
2.5
2.5
2.5
1.4
1.4
1.0
1.0
0.60
0.90
0.90
0.20
0.20
""
aSource:Spence and Markin (1974).
-— « No data
192
-------
Council for Agricultural Science and Technology (1976) noted, mirex is
extremely resistant to biological degradation.
It has been estimated that mirex has a half-life of 12 years
(Holden, 1976). This may actually be an underestimation, judging by the
findings of Carlson, et al., (1976) who were able to experimentally
account for about 50 percent of originally applied mirex after a 12-year
period. However, their data do show a number of degradation products,
including Kepone (a major degradation product) and dechlorinated mono and
dihydro products demonstrative of a pathway by which mirex can ultimately
disappear from the environment.
Physical runoff is a possible transfer mechanism between the soil
and water compartments. Actual runoff experiments on mirex do not appear
to have been reported. Water and sediment analyses have been conducted,
but directf aerial deposition in the water body or stream appears to have
also bee'n a possibility, so that runoff could not be measured
quantitatively.
Pesticide runoff from a Mississippi Delta watershed has been
experimentally determined by Willis, et al., (1976), who showed mean
annual concentrations of trifluralin, DDE, DDT, and toxaphene of 0.2 to
11 ppm in field runoff. The low solubility of mirex would probably
preclude the attainment of such concentrations, but mirex could easily be
associated with a mean sediment loss such as the 27.6 metric tons/ha
(12.3 tons/ac) also observed in this study.
7.2.3 Water and Sediments
As noted in Section 2.3.1.1, the theoretical solubility of mirex is
in the ppb range or below. Water has evidently proven to be a difficult
substrate to work with, and it has been difficult to differentiate
between mirex in solution and that associated with ultra fine suspended
material present. Markin, et al., (1972) reported that earlier analyses
of 50 water samples collected routinely following mirex application
failed to detect mirex with techniques possessing 0.01 ppb sensitivity.
Borthwick, et al., (1973) reported a similar lack of success in detecting
mirex in estuarine samples. Alley (1973) also states that mirex has not
been observed in natural waters with analytical techniques sensitive to
0.01 ppb. Some of the work at his laboratory on water from a creek whose
entire watershed had been treated with mirex bait indicated that a
substance tentatively identified as mirex can be observed at the 0.1 ppt
level, an almost imperceptible level, and one which the authors suggest
may have an insignificant environmental impact. The Mirex Advisory
Committee (1972) reported that several investigators had found mirex
residues of 0.5 to 1.0 ppb in pond water samples, but these were from
ponds pretreated with 0.5 to 1.0 ppm mirex, respectively.
Spence and Markin (1974) also analyzed time-variant mirex
concentrations in pond water and sediments in two Mississippi and
Louisiana mirex-treated test plots analyzed for soil concentrations.
193
-------
Water was sampled by passing it successively through a cellulose
cartridge filter (sediment) and an activated charcoal cartridge filter
(dissolved substances). Samples were taken at the surface and at the
bottom (1.5 m depth). Sediments were sampled at 10 locations around the
pond.
Results of the water analyses (Mississippi test plot) are shown in
Table 1.2. Water samples from the bottom of the pond showed residue
values which remained higher and more constant than those from the
surface of the pond. Most of the results, at either depth, were in the
parts per trillion range. Results of the sediment analyses are shown in
Table 7.3- As in the soil samples, the results for Mississippi were
higher and more variable, but all samples (with one exception) were below
1 ppb.
In view of the insolubility of mirex in water and the rapid
adsorption onto particulate matter which ultimately settles to the
bottom, mirex is not expected to be subject to photochemical degradation
in estuarine environments. Because mirex resists decomposition and is
virtually inert under normal environmemntal conditions, it will not
remain long in the water column but may have an appreciable lifetime in
the sediments. (See Sections 2.3.2.1 and 7.2.3.1). Transportation of bait
particles by surface runoff is a more likely source of stream and lake
contamination (Jones and Hodges, 1974).
The Mirex Advisory Committee (1972) reported sediment sample
concentrations of 0.01 to 21 ppb from fresh water ponds pretreated with
mirex; Van Valin and O'Donnell (1968) found ranges of from 0.09 to 32.7
in sediments from four ponds treated with 0.1 ppm of mirex.
In the work of Borthwick, et al., (1973) on the behavior of mirex in
estuaries, analysis of sediment samples for mirex gave negative results
(0.01 ppm) except in six instances, in which concentrations ranged from
0.01 to 0.07 ppm.
A number of field studies indicate that mirex is very stable in mud
and sediments. The analyses reported by Carlson, et al., (1976) of muck
samples from a pond bottom at the site of a crash of a plane carrying
mirex bait showed a concentration of 0.27 ppm of mirex plus degradation
products. This is of course, a special case, and is not representative of
soil concentrations to be expected from the utilization of mirex for fire
ant control.
Further evidence of the stability of mirex in sediments is furnished
by recent data from Lake Ontario. Mirex was first reported in fish caught
in northern Lake Ontario by Kaiser (1971*). Following this discovery,
several hundred sediment samples recovered by a large scale geological
survey of the lake conducted by the Canadian Centre for Inland Waters in
1968 were analyzed for mirex.
-------
TABLE 7.2 MIREX RESIDUES IN FILTERED WATER COLLECTED IN
MISSISSIPPI (1972).
\J1
Mlrex Concentration, ppb
Days
Posttreatment
Pretreatment
1-3 hours
1
2
3
7
14
21
28
35
42
49
56
63
70
77
84
91
98
105
112
Cellulose
Cartridge
Neg
0.033
0.530
0.001
0.001
0.001
0.003
0.002
Neg
0.001
Neg
0.004
0.002
0.001
0.001
0.001
0.001
0.002
0.001
0.001
0.001
Filter System 1
(Deepest Point)
Activated
Carbon
Cartridge
Neg
Neg
Neg
Neg
0.006
0.007
0.010
0.012
0.010
0.012
0.003
0.004
0.003
0.009
0.010
0.005
0.010
0.003
0.015
0.003
0.002
Total
Neg
0.033
0.530
0.001
0.007
0.008
0.013
0.014
0.010
0.012
0.003
0,008
0.005
0.010
0.011
0.006
0.011
0.005
0.016
0.004
0.003
Cellulose
Cartridge
Neg
0.007
0.008
0.003
0.001
0.005
0.006
0.002
0.001
Neg
Neg
Neg
Neg
0.001
0.001
0.001
0.002
0.002
0.003
0.007
0.005
Filter System 2
(Pond Surface)
Activated
Carbon
Cartridge
Neg
0.009
0.012
0.004
0.002
0.001
0.001
0.003
0.002
0.002
0.001
0.002
Neg
0.001
0.001
0.001
Neg
0.001
Neg
0.003
0.002
Total
Neg
0.016
0.020
0.007
0.003
0.006
0.007
0.005
0.003
0.002
0.001
0.002
Neg
0.002
0.001
0.001
0.002
0.003
0.003
0.010
0.007
Source: Spence and Markin (1974).
Neg » No ndrex at level of detection.
-------
TABLE 7.3 MIREX RESIDUES IN SEDIMENT COLLECTED IN MISSISSIPPI
(1972) AND LOUISIANA (1971-72) a
Posttreatment
Pretreatment
1-3 hours
1
2
3
7
14
21
28
35
42
49
56
63
70
77
84
91
98
105
Pretreatment
1-3 hours
3
4
7
17
25
31
38
45
54
69
77
90
117
164
185
223
268
337
374
Mirex, ppb
Mississippi
0.06
0.16
0.41
0.17
0.51
0.11
0.11
0.30
0.93
1.1
0.85
0.04
0.03
0.20
0.01
0.02
0.05
0.10
0.01
0.76
Louisiana b
Neg
Neg
Neg
Neg
0.02
0.04
0.30
0.70
0.60
0.03
0.08
0.10
0.10
0.60
0.30
0.20
0.09
0.06
0.50
0.16
0.40
aSource: Spence and Markln (1974).
Louisiana rainfall not recorded.
m No mlrex at level of detection.
196
-------
Analysis of these sediment samples revealed the occurrence of mirex
in two anomalous zones which coincided with input from the Niagara River
in the western end of the lake, and from the Oswego River at the eastern
end. The occurrence of these anomalies was confirmed by a 1976 resampling
program conducted jointly by Canada and the New York State Department of
Conservation. The Hooker plant at Niagara Falls is the presumed source of
the Niagara River "hot-spot". As a result of the analysis of bottom
sediment samples taken up the Oswego River, the Armstrong Cork Company
manufacturing plant located 14 km upstream of the river mouth was
identified as an industrial source. Known use of Dechlorane fire
retardant by this plant indicated a substantial loss (estimated at 450
kg) approximately 15 years ago. Mirex concentrations of sediments in the
vicinity of this plant ranged from 100 to 1600 ppb (Thomas, et al., 1978).
Of the 229 samples analyzed, only 75 (33 percent) contained
detectable residues of mirex. Concentrations of mirex in the 75 samples
ranged from 0.8 to 40 ppb, with a mean of 6.9 ppb and a standard
deviation of 8.3 ppb (Thomas, et al., 1978). The distribution of mirex is
shown in Figure 7.1. No mirex was detected over a large portion of the
lake, particularly in the northern half. The two high concentration zones
are quite evident. Thomas, et al., made estimates of the possible mirex
inventory in the top 3 cm of sediment, based on sediment analyses. These
calculations, summarized in Table 7.4, suggest that several hundred
kilograms of mirex may be trapped in Lake Ontario sediments.
A water quality criteria value for mirex of 0.001 ppb is suggested
by the recently issued Quality Criteria for Water (U.S. Environmental
Protection Agency, 1976a). This is based on applying a 1/100 safety
factor to the lowest levels at which effects on crayfish have been
observed. This level may be difficult to apply and interpret, since it
lies at the lower detection limit for mirex.
7.2.3.1 Mobility and Persistence in Water and Sediments—
There are few data bearing on the mobility and persistence of mirex
in water and in sediments. The solubility in water is so low that mirex
concentrations appear more often than not to be below the limit of
detection, precluding the kind of mass balances needed to assess
transport. The water analyses available suggest that water is not a
significant transport mode.
Mirex in sediments appears to be subject to decomposition mechanisms
similar to those in soil, except for the absence of exposure to
photolysis. Accordingly, persistence can be expected to be high. The
investigation of Carlson, et al., (1976) on the Sebring, Florida, muck
(which had received a massive dos.e of mirex as a result of a plane crash)
showed the presence of decomposition products analogous to those found in
aged soil samples from another site. The presence of mirex in sediments
in the Oswego River (Section 7-2.3) presumably 15 years after its
original discharge is further evidence of its stability.
On the basis of the earlier work by Hill and McCarty (1967) on
chlorinated hydrocarbons and the more recent work on mirex by Andrade and
197
-------
MIREX (ppb)
{""""I Less thon I
CZ3I-5
KV'C'/j 5**"" IO
Figure 7.1. Mirex concentration in Lake Ontario sediments
Source: Thomas, et al (1978). Reprinted, with permission,
from J. Great Lakes Research, (c) Internet. Association for
Great Lakes Research (1978).
-------
TABLE 7.4. MIREX IN LAKE ONTARIO SEDIMENTS - 1968'
Mlrex in Dried
Lake No. Sediment, ppb Mlrex in
Surface of Standard 3 cm Depth, »c
Occurrence Area, km^ Samples Mean Deviation kg
Niagara Anomaly
Os we go Anomaly
Other Samples
2349
1967
1117
30
27
16
10.0
7.3
5.6
11.0
6.7
9.3
366
224
98
aSource: Thomas, et al (1978). Reprinted, with permission, from J. Great
Lakes Research, (c) Internat. Association for Great Lakes Research (1978).
bSediment density of 2.6.
f»
80 percent assumed mean water content (mean value for surficlal 3 cms from 11
cores).
199
-------
Wheeler (VjylJ), anaerobic deoompoaition ia a poaaibillty, More reaearoh
appear* to be needed in this area.
7,2,*! Air
No analyses of ooncentrat tone of ml rex In the atmoaphere have been
found in the literature, Since mi rex in use la dlaperaed through the air
only in aasoolatton with relatively ooarae corn oob grit partiolea which
would nettle out rapidly, amounta remaining airborne would be expected to
i>e Insignificant,. With Us high melting point ('183 G) and very low vapor
pi-ensure (h x iO mm Hg at 50 C), volatiHiation from bait on the ground
would also be expected to be ineignifleant.
7- < DISTRIBUTION OP KEPONE IN THE PHYSICAL ENVIRONMENT
7.1.1 Entry into the Environment
Kepone'» principal uae has been in tropical regions out aide of the
United States for control of the banana root borer, The principal uses in
the U.S. have been for control of ante and roaohea around homes and
buildings and for wlreworm control in the southeastern eta tea, but theae
have been insignificant , relatively consuming only between 1 and 10
peroent of U.S. production. Aa aummariaed in Section ?,5,2.?» this might
represent a total uaage of no more than 13,000 to 150,000 kg of Kepone
aince its nommeroialiiation in the late 1930'a, it IB clear that Kepone
waa a very minor insecticide. Aa noted in EPA'a Position Document 3»
because of its email domestic uae, which was primarily nonagrloultural,
Kepone waa given low priority on the list of peetloidea for which
information on residues was aought and on which research waa conducted
(U.S. Environmental Protection Agency, 1976b).
Some early registered uses of Kepone were allowed only if no
residuea could be detected, However, as methods of reaidue detection
became more sophisticated, the expectation of finding no reaiduea of any
pesticide used on food cropa became unrealiatio. In June, 1965, a
committee of the National Academy of Sciences, National Reaearoh Council,
evaluated the practice of registering peatiolder for uae on food crops on
0uoh a lias la and concluded that it should no longer be allowed (U,,S.
Environmental Protection Agency, 1976a).
On February 1, 1968, all uaea of Kepone on food oropa were cancelled
except for bananaa, A tolerance of 0.1 ppm in whole bananaa waa
established on November 4, 1970. Subsequently, registration waa granted
for- uae of a 9 percent Kepone duat formulation against banana-root borers
(U.S. Environmental Protection Agency, 1976a).
•Aa noted in Section 6.3.3, this tolerance waa revoked on January 87,
1978.
800
-------
Most of the Kepone used in the U.S. Is contained in trap* or
dispensed indoors or near homea, Thua, 1n normal uae, there would be very
little reaaon to determine aoil, water, and air concentratlone of Kepone,
and, not unexpectedly, auoh data are not. to be found in existing
literature.
Had It not been for the Life Soienoea Product* Company incident at
Hopewell, Virginia, data on environmental oonoentrationa of Kepone would
ntiU be eaaentially non-existent, However, aa a reault of that incident,
hundreda of Kepone analyaea have been performed during the past two years
on soil, water, and air samples from the area in and around Hopewell, and
from the Jamea River and Cheaapeake Bay. Sampling and analysts in at Hi
continuing, and it will be aome time before formal reports on thla
incident appear in the aoientiflo literature. Preliminary reports and
memoranda have been prepared by the various State and Federal agencies
involved in the investigation, and the following dlaouaalona are baaed on
theae.
Zt ahould be reoogniaed that theae environmental oonoentrationa are
in no way representative of the intended uae of the product, but are,
instead, the reault of maaalve unapproved Kepone diaohargee from a alngle
point aouroe and repreaent a unique aituatlon, having no counterpart
elaewhere in the U.S.
There ia oonaiderable uncertainty aa to how much Kepone haa eaoaped
into the environment during ita manufacture at Hopewell, Virginia. Some
aolubiliied Kepone waa loat routinely from the precipitation and washing
of the Kepone product, and EPA eatimatea of theae quantities have been
compiled (Smith1, 1976| U.S. Environmental Proteotlon Agency, 1976o).
Theae were email quantttlea, leaa than 1 kilogram from AlUed'a 1971-74
•emiworka operations, and per ha pa 29 kg from LSPC operations in 1974-75,
Compared with the 45,000 kg (100,000 Ib) whioh the Virginia Institute of
Marine Science haa estimated lies on the bottom of the Jamea River (U.S.
Environmental Protection Agency, 19?6d), theae quantities are trivial,
Although the records of operationa at LSPC were fragmentary and
incomplete, aubaequent hearings have indicated the environmental
contamination of the Jamea River resulted from unapproved discharges of
groaa quantitiea of Kepone from this plant. The actual amount will
probably never be known, but it appears certain that it waa thouaanda of
kilograms.
7.3.8 Sofl
Dust collection waa very poorly handled at LSPC, and the looal
neighborhood waa subjected to considerable fallout. Looal air
concentrations were very high (aee Section 7«i.4), diminishing with
diatanoe from the plant.
Soil samples taken adjacent to the LSPC manufacturing site on
Terminal Street contained from 1 to 9 percent Kepone (10,000 to 80,000
ppm). Surface aoil samples taken due east of the manufacturing aite alao
801
-------
contained up to 300 ppm of Kepone with the more distant surface soil
samples — up to approximately 1000 meters (3000 feet) from the
manufacturing site ~ containing 2 to 6 ppm of Kepone (U.S. Environmental
Protection Agency, 1975a). It has been estimated that as much as 1 metric
ton may have been deposited on the ground within a 1000-meter (3000-foot)
radius of the plant (Blanchard, 1976). No data on soil concentrations
beyond the Hopewell corporate limits were found.
7-3.2.1 Mobility and Persistence in Soil—
Gawaad, et al., (197D investigated the leaching of Kepone and other
organochlorine and organophosphate insecticides from several types of
Egyptian soils. Simple percolation tests were conducted, using
soil-filled metal cylinders perforated at the bottom to permit collection
of leachate. The insecticides and their degradation products were leached
more readily from light soils such as sandy loams and calcareous sandy
loams than from heavier soils like clay loam and clay. The amount of
applied pesticide which was recovered in the leachate from a 24-hour
period ranged from 1.2 percent in an El-Mansoura clay loam to 36.8
percent in a Sacka sandy clay loam. In all cases, the chlorinated
hydrocarbons were leached more readily than the organophosphates (Gawaad,
et al., 1971). According to a U.S. EPA report (1975b), Gawaad, et al.,
concluded that contamination of lake or river water could result from the
use of Kepone.
Although little is known about the persistence of Kepone in soil,
data submitted by Allied Chemical Corporation showed essentially no
decline in residual levels 154 days after treatment (U.S. Environmental
Protection Agency, 1975b). Clearly, Kepone is very stable and persistent
in soils. The EPA report expressed two major concerns regarding the
effects of Kepone on soils. First, because oxidation of nitrite to
nitrate is depressed after Kepone application, a temporary buildup of
nitrite may occur in treated soil, which in turn, may adversely affect
some plant species. Secondly, the persistence of Kepone in soils suggests
the possibility that residues may be taken up into edible portions of
rotational crops such as soybeans and small grains, although no
experimental data were available on this topic.
There are very few data available on the persistence of Kepone in
soil. By analogy, it would be expected to exhibit almost as much
stability as mirex, and to have a long half-life in soil.
7.3.3 Water and Sediments
The preliminary 1975 survey results (U.S. Environmental Protection
Agency, 1975a) indicated that in the Appomattox River upstream of the
plant, Kepone was detected at 0.1 ppb; in the James River near the mouth
of Bailey's Creek levels up to 0.3 PPb were measured. Kepone
concentrations in other samples from the James River ranged from 0.1 to 4
202
-------
ppb. Kepone was undetectable ( 50 ppt) in the York River, the next river
basin north of the James River, which also empties into Chesapeake Bay
above the James River.
An ice processing plant, which crushed and bagged ice made
elsewhere, was located across the street from the LSPC plant about 50
meters (150 feet) away. The 1975 survey indicated that ice stored at this
facility contained from 0.1 to 1 ppm of Kepone. Subsequent samples taken
in December, 1975, 4 months after closure of the LSPC plant, were found
to contain 1 to 50 ppb. The processor was closed and moved to another
location for approximately 8 months (Virginia Department of Agriculture
and Commerce, 1977).
Tap water from the Hopewell area was determined to contain no
detectable Kepone in the preliminary 1975 survey (U.S. Environmental
Protection Agency, 1975a); this was confirmed by a December, 1975, sample
(Virginia Department of Agriculture and Commerce, 1977).
River bottom sediment analyses showed nondetectable levels of Kepone
(10 ppb) in the western reaches of the Appomattox River, upstream of the
Kepone manufacturing site. In the area of Bailey's Creek, into which the
Hopewell STP discharges, bottom sediments ranged between 1 and 1* ppm.
Sludge samples from the STP holding pond and sludge disposal landfill
contained from 200 to 600 ppm Kepone (U.S. Environmental Protection
Agency, 1975a). Later sampling (January - May, 1976) by the Virginia
Water Control Board, found levels in sediments in Bailey's Creek as high
as 30 ppm. Bailey Bay sediments had Kepone concentrations of 1 to 10 ppm
in three-fourths of the samples. Down river of this, sediment
concentrations were somewhat erratic, varying between 0.02 and 1 ppm
(U.S. Environmental Protection Agency, 1976d). The high levels in the STP
and in Bailey's Creek appear to be the result of the discard of
quantities of Kepone from the manufacturing plant through the Hopewell
sewer system, and not runoff from Kepone deposited on the soil in the
vicinity of the plant.
In 1976, the U.S. Army Corps of Engineers undertook several series
of water and sediment tests to determine the extent of Kepone
contamination in the James River navigation channel and the effects of
channel dredging on redispersion of the Kepone. The first series of these
tests was performed during January, February, and March, 1976, in order
to determine whether Kepone was present at various locations on the James
River including the Hampton Roads and Elizabeth River area. The results
of these tests (Table 7.5) indicated that a Kepone contamination problem
existed from Hopewell, Virginia, nearly to Newport News, Virginia (U.S.
Army Corps of Engineers, 1976). Nine sediment samples taken in the
Hampton Roads area of Newport News showed undetectable Kepone ( 0.1
ppb), indicating that Kepone redispersion would not be anticipated to
result from dredging projects in this area, which is about 110 km (69 mi)
downstream from Hopewell.
203
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TABLE 7.5 SUMMARIZED SEDIMENT AND WATER
ANALYSES, JANUARY, 1976 a
Location
Allied Pier
Windmill Point
Dancing Point
Goose Hill Shoal
Skiffes Creek
Approximate
River Mile
69
57
42
27
20
Kepone
Sediment ,
0.46
0.41
0.81
0.87
0.48
0.40
0.30
0.09
Concentration
ppm Water, ppb
<0.05
<0.05
<0.05
<0.05
. 0.04
<0.05
a Source: U. S. Army Corps of Engineers (1976).
TABLE 7.6 RESULTS OF ANALYSIS OF THREE CORES FROM WINDMILL
POINT SHOAL TAKEN BEFORE DREDGING.a,b
Core Depth
cm
0-15.24
15.24-30.48
30.48-45.72
45.72-60.96
60.96-76.20
In
0-6
6-12
12-18
18-24
24-30
L. Windmill Point
Upstream end
0.23
0.39
0.24
0.14
-(C>
Kepone, ppm
Core Location
L. Windmill Point
Middle
0.27
0.35
0.14
0.34
~ (C>
L. Windmill Point
Lower End
0.09
0.07
0.04
0.05
0.02
aSource: U. S. Army Corps of Engineers (1976).
b Samples taken in January, 1976.
Not samples at this depth.
20U
-------
In another Corps of Engineers test, sediment cores from the Windmill
Point area just below Hopewell (River Mile 57) were analyzed to a depth
of 76 cm (30 in). These results, shown in Table 7-6, indicate that the
near-field sediments are contaminated with Kepone to a considerable depth.
Profiles of James River sediment Kepone concentrations have been
developed by the U.S. Environmental Protection Agency, as of mid-1976,
from Hopewell to Newport News, as shown by Figures 7.2, 7.3, and 7.4
(U.S. Environmental Protection Agency, 1976d). Maximum concentrations
were found at Bailey's Creek (
-------
ro
o
ON
JAMES RIVER SEDIMENT
KEPONE CONCENTRATIONS
EPA REGION
CHESAPEAKE BAY PROGRAM
AUGUST 1976
> 10.0
1.0 to 9.99
O.I to 0.99
0.02 to 0.09
NONE DETECTED
EPPES ISLAND
Figure 7.2. Janes River sediment Kepone concentrations In the vicinity of Hopewell, Virginia
Source: U.S. Environmental Protection Agency, (1976d).
-------
ro
o
JAMES RIVER SEDIMENT
KEPONE CONCENTRATIONS
EPA REGION III
CHESAPEAKE BAY PftOGRAM
AUGUST 1976
PPM
> 10.0
1.0 to 9.99
O.I to 0.99
0.02 to 0.09
NONE DETECTED
HARLffS CITY
WINDMILL
POIN
Figure 7.3. James River sediment Kepone concentrations from Richmond, Virginia, to the mouth of the
Chlckahomlny River
Source: U.S. Environmental Protection Agency, (1976d).
-------
ro
o
cx>
10.0
10 to 9.99
O.I 10 0.99
0.02 to 0.09
NONE DETECTED
JAMES RIVER SEDIMENT
KEPONE CONCENTRATIONS
PORTSMOUTH
EPA REGION III
CHESAPEAKE BAY PROGRAM
AUGUST 1976
Figure 7.4.
James River sediment Repone concentrations from Williamsburg, Virginia, to Newport News
Source: U.S. Environmental Protection Agency, (1976d).
-------
7.3.4 Air
Air monitoring stations in Hopewell were located at the Hopewell
News building, 200 m (0.13 mi) south of the plant site, and at the
Hopewell airport 5.2 km (3.24 mi) to the east. Other sites were located
in nearby communities at distances of 12.5 to 25 km (7.8 to 15.6 miles).
Hi-Vol samples collected at the station 200 meters distant during the
period from March, 1974 through April, 1975, while the plant was in
operation, were found to contain from 2 to 50 micrograms of Kepone per m
of air. Kepone concentrations varied depending on the length of sampling
time, weather conditions, and date of collection. During this same
sampling period, the percent of Kepone in relation to the total suspended
particulates (TSP) ranged from less than 1 percent to more than 40
percent.
Hi-Vol air filters taken from the Hopewell airport, the Colonial
Heights area, and the most distant site (South Richmond, which is
approximately 25 km (_16 mi) from the manufacturing plant) contained
between 0.1 and 20 ng/nr (U.S. Environmental Protection Agency, 1975a).
A later 1976 reentrainment investigation by EPA, with assistance
from the State of Virginia, showed that some Kepone becomes airborne up
to 0.8 km (0.5 mile) from the LSPC site due to local traffic and
meteorological conditions (U.S. Environmental Protection Agency, 1976d).
There are no data on the mobility and persistence of Kepone in air.
Air would not be a transport mode for Kepone in its insecticidal use, but
it obviously was, locally at least, around the LSPC plant.
7.4 DISTRIBUTION OF MIREX AND KEPONE
IN THE BIOLOGICAL ENVIRONMENT
7.4.1 Accumulation in Non-Target Organisms
Naqvi and de La Cruz (1973) investigated the quantities of mirex
stored in animal tissues and thereby its transport to all trophic levels
of the food web. They attempted to evaluate the incorporation of mirex in
the environment on the basis of residue levels of animals collected from
various habitats in Mississippi which had received varying degrees of
mirex treatment. Average residues of pooled samples constructed according
to type of organism revealed the following hierarchy of accumulation —
annelids (0.63 ppm), crustaceans (0.44 ppm), insects (0.29 ppm), fish
(0.26 ppm), and mollusks (0.15 ppm). Classification by habitat identified
the highest residues among: pond (0.37 ppm), creek (0.31 ppm), grassland
(0.28 ppm), lake (0.27 ppm). Lowest residues were found in the estuarine
habitat (0.20 ppm). The physical parameters of the habitat were found to
greatly influence the accumulation of mirex. For example, residue levels
in enclosed small ponds were slightly higher than in free-flowing creeks;
levels in creeks were higher than in larger bodies of lakes; and levels
in lakes were higher than in the more contiguous bay-estuary. One finding
of vital importance was the discovery of mirex residues in animals
209
-------
collected from areas with no history of direct mirex treatment, which
demonstrated widespread movement of mirex in the environment. Although
residue levels varied greatly, 94 percent of the samples contained less
than 1 ppm mirex, and 2.5 percent of the samples contained greater than 2
ppm. Laboratory studies by Ludke, et al., (1971) in simple food chains
have shown that food items containing 0.5-1.0 ppm of mirex caused up to
53 percent mortality in certain aquatic animals. The authors concluded
that if the findings of Ludke, et al., can be extended to natural
environments, the residue levels detected in this study are potentially
poisonous to prospective consumer species which are highly sensitive to
mirex.
Collins, et al., (1974) conducted a similar survey in Louisiana
designed to investigate and compare accumulation of mirex residues in
selected vertebrates and selected components of the human food chain for
1 year following the aerial application of mirex bait. Vertebrates in
general had quite low mirex residues (0.001 to 0.005 ppm); however,
certain birds such as shrikes and mockingbirds accumulated residues
ranging from 1 to 8 ppm. Reptiles and amphibians generally accumulated
lower residues than did birds and mammals, probably owing to the
relatively greater volume of food consumed by birds on a per weight
basis. As expected, predatory species of fish such as largemouth bass
contained higher mirex concentrations than did omnivorous species.
Mirex was also detected in 77 percent of the human food chain items
which were surveyed. These data are shown in Table 7.7. Mirex was not
detected in beef fat prior to mirex treatment or 1 year after treatment.
Low concentration levels were found in milk (0.001 to 0.002 ppm), chicken
eggs (0.001 to 0.49 ppm), and chickens (0.004 to 0.515 ppm).
Borthwick, et al., (1973) conducted extensive field studies of
coastal areas of North Carolina in order to monitor the movement and
accumulation of mirex in the estuarine system following aerial
application. The data revealed that (1) mirex was translocated from
treated lands and high marsh to estuarine biota — all animal classes
contained mirex, and (2) biological magnification of mirex occurred —
especially in predators such as raccoons and birds. Mirex residue ranges
for the respective sample categories were: water ( * 0.01 ppb), sediment
(0 to 0.07 ppm), crabs (0 to 0.60 ppm), fishes (0 to 4.4 ppm), and birds
(0 to 17.0 ppm). Mirex was not detected in any pretreatment samples of
crabs, shrimp, fish, sediment, or water taken from the six monitoring
stations. Table 7.8 shows the biological concentration of mirex in the
estuarine food web. The authors believe that variables such as proximity
to the treated area, duration of exposure to a mirex-contaminated
habitat, seasonal habits, avoidance ability and position in the food web
are the most important determinants of mirex accumulation levels.
Additional parameters of potential importance relate primarily to the
amount of mirex available in the environment including rate and method of
application, amount of rainfall, surface runoff, variations in sea level,
and degradation.
210
-------
TABLE 7.7. Him RESIDUES IN HUMAN FOOD C1IAIH FROM FRETREATMEtlT TO 1 YEAR AFTER SINGLE KIREX APPLICATION1*>b
IV)
Mlrex Concentration,
Pretreatoent
Food It en
Milk
Chicken egga
Dooeatlc chicken*
Beef fat
Fish
Bluegllla
Brown bullhead*
Largenouth be**
Game animals and bird*
Eastern cottontalla
Opossums
Bohvhlte quail
Sample
alee
I qt
12
2
1 Ib
28
5
1
0
1
1
Residue
found
0.015
1ID
MD
0.003
0.001
ND
0.120
0.113
2 veeks
Sanple
•lie
1 qt
12
2
0
15
6
1
1
2
1
Realdue
found
HDC
0.493
0.004
0.012
0.004
0.018
MD
0.044
0.012
1 month
Sample
site
1 qt
12
2
0
25
20
1
1
0
1
Realdue
found
0.022
0.005
0.036
0.019
0.113
0.032
ND
0.475
ppn
3 months
Sample
alee
1 qt
12
2
0
79
4
1
0
1
1
Realdue
found
0.001
0.007
0.515
0.041
0.086
0.624
0.009
1.502
6 months
Sanple
site
1 It
12
2
0
34
7
0
1
1
0
Realdue
found
MD
ND
0.010
0.009
0.003
ND
0.004
9 months
Sample
alee
1 qt
12
2
0
36
4
0
1
0
1
Realdue
found
ND
0.011
0.201
0.009
0.003
0.254
0.064
12 me
Sample
alee
1 qt
12
2
1 Ib
15
10
0
0
0
2
intha
Reaidue
found
ND
0.001
0.014
ND
0.018
0.010
0.036
'Source: Collins, et al. (1974).
"Average of all samples collected fro* eatire study area at Indicated sampling interval.
eND-no detectable realduea.
-------
TABLE 7.8. ACCUMULATION OF MIREX IN BIOTA3
Residue range, Posttreatment samples with
Sample ppm^ mirex residues, percent
Water
Sediment
Crabs
Fishes
Shrimps
Mammals
Birds
<0.01 ppb
0 - 0.07
0 - 0.60
0 - 0.82
0 - 1.3
0 - 4.4
0 -17.0
0
3
31
15
10
54
78
kSource: Borthwick,et al. (1973)
0=<0.01 ppm.
212
-------
The above data are illustrative of environmental concentrations
resulting from the utilization of mirex as a pesticide. Some data are
also available on mirex (and Kepone) accumulation in non-target organisms
as a result of losses during manufacture. Mirex (or Dechlorane) has been
found in fish from Lake Ontario by the Canadian Environment Ontario
pesticide laboratory. Approximately 1000 fish from various locations in
the Great Lakes were analyzed, but only fish from Lake Ontario were found
to contain mirex residues exceeding U.S. Federal guidelines of 0.1 ppm
(Anon., 1976a).
Mirex has also been found in Lake Ontario fish by the New York
Department of Environmental Conservation, which has issued an order
banning consumption of fish contaminated by mirex and Kepone (Anon.,
1976b). Affected species are coho and Chinook salmon, brown bullheads,
catfish, lake trout, smallmouth bass, and members of the alewife-herring
family.
Taken together, the surveys of Borthwick, et al., (1973), Naqvi and
de La Cruz (1973)f and Collins, et al., (1974) demonstrate quite
convincingly that low levels of mirex residues remain in the environment
and are concentrated by some species. Collins, et al., (1974) concluded
that although all residue levels reported by their survey were well below
the levels reported by others as causing acute toxicity to rats, mice,
birds and fish, the lack of information on the long-range effects of low
chronic dosages on non-target organisms precludes any definite statements
concerning the potential long-term environmental impact of these mirex
residues.
Kepone has been found in freshwater trout and suckers taken from
Spring Creek, which runs near the Nease Chemical Company plant in State
College, Pennsylvania. This plant produced Kepone in 1958-1959 and 1963,
and manufactured mirex as late as 1974 (Anon., 1976b). Trout accumulated
Kepone in amounts ranging from 0.15 to 0.17 ppm and the suckers had
levels as high as 0.18 ppm (Anon., 1976a). Kepone's continued presence in
this stream and its inhabitants is further evidence of its persistence in
the environment. The gross losses of Kepone from the ill-equipped and
poorly operated LSPC plant at Hopewell, Virginia, has caused major
contamination of aquatic organisms of the James River, extending even
into Chesapeake Bay (see Section 6.5.2).
213
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7.5 REFERENCES
Alley, E. G. 1973. The Use of Mirex Control of the Imported Fire Ant.
Environmental Quality 2(1): 52-61.
Andrade, P.S.L., Jr., and W. B. Wheeler. 1974. Biodegradation of Mirex
by Sewage Sludge Organisms. Bull. Environmental Contain. Toxicol.
11(5): 415-416.
Anonymous. 1976a. Kepone, Mirex Cited in Lake Ontario Fish Ban. Toxic
Materials News 3(20): 155-156.
Anonymous. 1976b. No Action Taken on Violative Kepone Residues in
Pennsylvania Sport Fish. Pesticide Chemical News 4(37): 24.
Bevenue, A., J. N. Dgata, L. S. Tengan, and J. W. Hylin. 1975. Mirex
Residues in Wildlife and Soils, Hawaiian Pineapple-Growing
Areas - 1972-74. Pesticides Monitoring J. 9(3): 141-149.
Blanchard, J. 1976. Kepone Fact Sheet. Internal Memo dated September
13- U.S. Environmental Protection Agency. 3 pp.
Borthwick, P. W., T. W. Duke, A. J. Wilson, Jr., J. I. Lowe,
J. M. Patrick, Jr., and J. C. Oberheu. 1973* Accumulation and
Movement of Mirex in Selected Estuaries of South Carolina,
1969-71. Pesticides Monitoring J. 7(1): 6-26.
Carlson, D. A., K. D. Konyha, W. B. Wheeler, G. P. Marshall, and R. G.
Zaylskie. 1976. Mirex in the Environment: Its Degradation to
Kepone and Related Compounds. Science 194(4268): 939-941.
Chambers, A. W. 1976. Information Pertaining to Product Mirex. Letter
of May 21, 1976, from A. W. Chambers, Hooker Chemical Corporation,
to Mr. G. A. Shanahan, Region II, U.S. Environmental Protection
Agency, New York, New York. 2 pp.
Collins, H. L., G. P- Markin, and J. Davis. 1974. Residue Accumulation
in Selected Vertebrates Following a Single Application of Mirex
Bait, Louisiana—1971-72. Pesticides Monitoring J. 8(2): 125-130.
Council for Agricultural Science and Technology. 1976. Fire Ant
Control. CAST Report No. 62. Council for Agricultural Science and
Technology, Iowa State University, Ames, Iowa. 28 pp.
214
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Gawaad, A.A.A.-W., M. A. Hamad and P. H. El-Gayar. 1971. Effect of the
Canal Irrigation System Used in the Persistence of Soil
Insecticides. International Pest Control 13(4): 8-10, 28.
Health Aspects of Pesticides Abstracts 5(4): 72-0686-90 .
Hill, D. W., and P. L. McCarty. 1967. Anerobic Degradation of Selected
Hydrocarbon Pesticides. J. Water Pollution Control Federation
39(8): 1259-1277-
Holden, C. 1976. Mirex: Persistent Pesticide on Its Way Out. Science
194(4262): 301-303.
Johnson, J. M., A. M. Dollar, and D. C. Cox. 1976a. Mirex Monitoring in
Hawaii - A Cooperative Venture. J. Environmental Health 38(4):
254-259.
Johnson, J. M., A. M. Dollar, and D. C. Cox. 1976b. Mirex Monitoring in
Hawaii...Monitoring Requirements. J. Environmental Health 38(5):
343-344.
Jones, A. S., and C. S. Hodges. 1974. Persistence of Mirex and Its
Effects on Soil Microorganisms. Agr. and Food Chem. 22(3):
435-439.
Kaiser, K.L.E. 1974. Mirex: An Unrecognized Contaminant of Fishes From
Lake Ontario. Science. 192: 523-524.
Legro, S. W. 1976. Discharges of Mirex Into Lake Ontario, Internal EPA
Memorandum from the Office of Enforcement to the Administrator.
May 6, 1976. 2 pp.
Ludke, J. L., M. T. Finley, and C. Lusk. 1971. Toxicity of Mirex to
Crayfish, Procambarus blandingi. Bull. Environmental Contam.
Toxocol. 6(1): 89-96.
Markin, G. P., J. H. Ford, J. C. Hawthorne, J. H. Spence, J. David,
H. L. Collins, and C. D. Loftis. 1972. The Insecticide Mirex and
Techniques for Its Monitoring. U.S. Department of Agriculture,
Animal and Plant Health Inspection Service, Hyattsville, Maryland.
APHIS 81-3. 19 PP.
Mirex Advisory Committee. 1972. Report of the Mirex Advisory Committee
to William D. Ruckelshaus, Administrator, Environmental Protection
Agency, February 4, 1972. Unpublished Report. 72 pp.
Naqvi, S. M., and A. A. de La Cruz. 1973. Mirex Incorporation in the
Environment: Residues in Non-Target Organisms - 1972. Pesticides
Monitoring J. 7(2): 104-111.
215
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Spence, J. H., and G. P. Markin. 1974. Mirex Residue In the Physical
Environment Following A Single Bait Application. 1971-72.
Pesticides Monitoring J. 8(2): 135-139.
Smith, W. C. 1976. Kepone Discharges from Allied Chemical Company.
Hopewell, Virginia. Internal EPA Memorandum. National Field
Investigation Center, U.S. Environmental Protection Agency,
Denver, Colorado. 33 pp.
Thomas, R. L., M. Van Hove Holdrinet, R. Frank, and L. J. Hetling.
1978. Mirex in the Sediments of Lake Ontario. J. Great Lakes
Research 4 (1):26-30.
U.S. Army Corps of Engineers. 1976. Kepone Sampling and Results for the
FY-76 and "T" Quarter Maintenance Dredging, James River, Virginia.
Norfolk District, October 6, 1976. 14 pp + Appendix.
U.S. Environmental Protection Agency. 1975a. Preliminary Report on
Kepone Levels Found in Environmental Samples from the Hopewell,
Virginia Area. Health Effects Research Laboratory, Research
Triangle Park, North Carolina. Unpublished Report. 33 pp.
U.S. Environmental Protection Agency, 1975b. Kepone. Office of
Pesticide Programs, Criteria and Evaluation Division. Unpublished
Report. 24 pp.
U.S. Environmental Protection Agency. 1976a. Quality Criteria for
Water, EPA 440/9-76-023- Washington, D.C. pp. 312-18.
U.S. Environmental Protection Agency. 1976b. Kepone: Position Document
3, Kepone Working Group, Washington, D. C. 27 pp.
U.S. Environmental Protection Agency. 1976c. Kepone Discharged from
Hopewell, Virginia, Sewage Treatment Plant. National Enforcement
Investigations Center, Denver, Colorado. 12 pp + Appendix.
U.S. Environmental Protection Agency. 1976d. Information Memorandum.
Review of the Chesapeake Bay Program Seminar on Kepone held at
Virginia Institute of Marine Sciences. October 12-13» 1976. 8 pp.
Van Valin, C. C., and J. O'Donnell. 1964. Equipment, Methods, and
Techniques. Chemistry Methods. In: Pesticide-Wildlife Studies,
1963: A Review of Fish and Wildlife Service Investigations During
the Calendar Year. U.S. Department of the Interior, Fish and
Wildlife Service, Washington, D. C. Circular 199, PP 35-36.
Virginia Department of Agriculture and Commerce. 1977. Summary of
Kepone Analysis of Foods. Undated. 3 PP«
Willis, G. H., L. L. McDowell, J. F. Parr, and C. E. Murphree. 1976.
Pesticide Concentrations and Yields in Runoff and Sediment from a
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Mississippi Delta Watershed. In: Proceedings of the Third Federal
Inter-Agency Sedimentation Conference, March 22-25, 1976, Denver,
Colorado. Water Resources Council, Sedimentation Committee.
PB-245 100. pp 3-54, 3-64.
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8.0 ENVIRONMENTAL ASSESSMENT
(Dr. Earl G. Alley)
8.1 ENVIRONMENTAL ASSESSMENT-MIREX
The bait technology used for this compound in control programs for the
imported fire ants allows its effective utilization at very low
application rates. Its use has not had a significant impact on wildlife
even in estuarine areas where its impact should be the greatest. Further,
its use is the only practical method for controlling an insect that poses
some hazard to human health and welfare.
There is, however, the potential for problems resulting from use of
this compound because it accumulates, and magnifies in food chains, is
not metabolized readily, and probably causes tumors in mice and rats.
Humans acquire residues, apparently as a result of use of mirex as an
insecticide. Millions of acres in the Southeastern United States were
formerly treated each year with low levels of this compound and it
persists in the environment for many years.
The risk vs benefit of continued use of these baits is difficult to
assess because neither is well defined. The risks are not proven risks
and the benefits are not predominantly economic ones. The primmary
environmental risk associated with continued use of mirex is to humans.
They will derive some benefit from its use and in the process be
subjected to certain levels of risk in terms of long term chronic effects.
Production in the United States of the toxicant for this pesticide was by
Hooker Chemicals and Plastics Corporation and by several smaller
companies under contract to Hooker from 1959 through 1975. Hooker did not
sell any of this compound for formulation of imported fire ant baits
after Allied Chemical stopped manufacture of the bait in 1975. After that
time the toxicant was imported from South America and the baits
manufactured by the State of Mississippi. From 1959-1975, 1,525,540 kg of
this chemical were sold by Hooker. Of this quantity 400,090 kg were used
for agricultural applications. In 1976-1977, 24,340 kg of technical mirex
was used in the manufacture of fire ant baits (Mississippi Department of
Agriculture and Commerce, 1978).
8.1.1 Uses
Use of the compound C1_C11p as an insecticide accounted for only
about 26 percent of its totaT utilization from 1959-1975. The portion of
this production used for mirex baits within the United States was perhaps
as little as 16 percent (250,000 kg). The other uses were predominantly
in flame resistant polymer formulations in electronic components,
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television components and fabrics. The primary use of this compound as an
insecticide was in a bait for the imported fire ants (Solenopsis richteri
and Solenopsis invicta). This bait was called mirex and during most of
the years it was employed it contained 0.3 percent toxicant. Over
100,000,000 acres were treated with 1.25 Ib/ac of this formulation during
a ten year period. In 1977, the formulation was changed to 0.1 percent of
toxicant and the application rate to one pound per acre. About 18,000,000
Ibs of this lower concentration bait was manufactured during 1977 and
will be distributed until June 30,1978 (Mississippi Department of
Agriculture and Commerce, 1978).
8.1.2 Analysis
Residue analysis for mirex may be done by standard methods for
chlorinated hydrocarbons using extraction with suitable solvents,
partitioning, Florisil cleanup, and electron capture gas chromatography.
Interference from PCB's (Arochlor 1260 and 125*0 may be a problem when
these compounds are present. Several methods for circumventing this
interference have been reported (Markin, et al., 1972; Lewis, et al.,
1976). Gas chromatographic retention times provide only equivocal
evidence for identity so independent confirmation is very important. Thin
layer chromatography is usually too insensitive to be a useful tool for
confirmation. Mass spectrometry provides a good confirmation tool. The
C_Clg fragment gives intense ions at m/e 27Q* 27*1 ^ . . The relative
intensities of these ions is determined by the Cl : Cl isotope ratio
which provides further evidence for the elemental composition of the
cluster.
8.1.3 Environmental Contamination
Contamination of the environment by mirex has been observed in the
lower Great Lakes from the manufacture of the toxicant and in the
Southeastern United States from its use in control programs for the
imported fire ant (Collins, et al., 1974; Kendall, 1977; Spence, et al.,
1974; Borthwick, et al., 1973). There is also evidence for pollution from
industrial utilization of this compound (Thomas, 1978). Although large
amounts of the compound have been used industrially, there are few
reports of residues that can be clearly associated with this type of use.
There appear to have been two clearly established routes of mirex
contamination of the environment. These are from the manufacture and
industrial use of the compound and from use of the compound in programs
for control of the imported fire ant. Levels in water and soil have been
near or below detection limits. When watersheds treated with 0.3 percent
baits were monitored mirex was found, at levels from 0.001 to 0.028 ppb,
entirely associated with particulate matter. The high levels appeared
only during major run-off events (Alley, unpublished results). At the
current application rates, the theoretical concentration in the top three
inches of soil is about 2 ppb. Concentrations found in sediments from
normal bait applications have been lower than this (Spence and Markin,
1974). Sediments near manufacturing facilities either making or using
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mirex contained up to 1600 ppb (Thomas et al., 1978). In Lake Ontario
only a few small areas are contaminated. Sediment samples from these
areas average about 7 ppb (Thomas, et al., 1978). Some decomposition to
dechlorinated mirex derivatives and kepone has been observed in
sediments. These reactions are, however, very slow. Contamination of the
biological environment by mirex has been the subject of many reports
(Collins, et al., 1974; Borthwick, et al., 1973, Naqvi and de la Cruz,
1973; Kendall, et al., 1977). The contamination in the Great Lakes has
resulted in residues in aquatic food chains (Hallett, et al., 1976). The
residues thhat result from application of baits for fire ant control
arise in both aquatic and terrestrial food chains with members of
terrestrial food chains exhibiting the highest residue levels.
Insectivorous birds are particularly prone to accumulate mirex residues
(Collins, et al., 1974; Kendall, et al., 1977).
The only report of acute poisoning of wildlife resulting from
utilization of mirex concerned crustaceans (Markin, et al., 1974).
Residues in wildlife are important, however, because of potential
contamination of human food supplies. Mirex is metabolized very slowly
and thus is magnified in food chains and stored in the lipid part of
tisses of contaminated organisms. Therefore, there exists the potential
for unacceptable levels of this chemical accumulating from repeated
applications over a number of years. In one study, levels in bobwhite
quail from treated areas were invariably greater than established
tolerances in food for human consumption (Kendall, et al., 1977).
Mirex is a very persistent chemical in the environment. Carlson, et
al., (1976) found that close to half remained after twelve years. They
found degradation products including hydrogen derivatives and Kepone. The
sites studied by these workers were ones that had had extraordinarily
heavy application of the pesticide and so these data probably reflect
slower degradation rates than would be observed for normal applications.
Metabolism is very slow but conversion has been reported in
microorganisms (Andrade, 1975) and in monkeys (Stein, et al., 1976).
Several other experiments with mammals reported that no mirex metabolism
occured (Ivie, et al., 1974; Mehendale, et al., 1972; Gibson, et al.,
1972; Wiener, et al., 1976).
Chemically, mirex is not very reactive. It is inert to strong acids,
bases and oxidizing agents but is reactive photochemically and under a
variety of reductive conditions. These reactions lead to dechlorinated
derivatives of mirex and Kepone (Dilling, et al., 1967; Alley, et al.,
1974a; 1974b).
8.1.4 Bioaccumulation
Uptake of mirex by plants fromm soil has been demonstrated; however,
magnification does not appear to be a problem (de la Cruz and Rajanna,
1975). Bioaccumulation in aquatic species has been the subject of a
number of laboratory and field studies. Hollister, et al., (1975) and
Sikka, et al., (1976) have observed accumulation by algae 350 to 5000
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times that in their environment. Studies with aquatic invertebrates have
generally shown high bioconcentration of mirex (de la Cruz and Naqvi,
1973; Bookhout and Costlow, 1976). Field studies have verified these
laboratory results (Lowe, et al., 1971). Fish accumulate mirex from their
environment and from their food supply in the environment (Collins, et
al., 1973) and in laboratory studies (Lee, et al., 1975; Lowe, et al.,
1971). Field studies have shown accumulation of residues in the higher
trophic levels, as would be expected if magnification through various
food chains was occurring (Hyde, et al., 1973). Many of the laboratory
experiments were performed using levels several thousand times in excess
of the solubility of the compound and in some cases several million times
the levels typically encountered in the environment. Therefore, these
accumulation data have been obtained with unrealistic conditions and are
poor models for prediction of environmental effects, particularly where
solubilizing agents have been used. Neverthe- less, it is evident from
field studies that bioaccumulation in aquatic ecosystems does occur.
Field studies of terrestrial species have shown that bioaccumulation
of mirex is a significant problem (Mirex Advisory Committee, 1972, Hyde,
et al., 1973; Collins, et al., 1974). Birds appear to be particularly
vulnerable to accumulation of residues (Collins, et al., 1974; Kendall,
1977).
8.1.5 Nonhuman Toxicology
Mirex has little effect on terrestrial or aquatic microorganisms
(Jones and Hodges, 1874; Brown, et al., 1975; Hollister, et al., 1975;
Sikka, et al., 1976).
In contrast, invertebrate species are very sensitive to mirex.
Contradictory evidence (Ludke, et al.; 1971; Muncie and Oliver, 1963) has
arisen because early workers did not recognize the delayed toxic response
of mirex. Not much credibility should be attached to acute studies with
mirex that show low toxicity but are 96 hours or less in duration. This
delayed toxicity is a major factor in the efficacy of mirex as an ant
toxicant because it allows time for distribution of the compound to the
entire colony including the queen and brood before toxic effects become
evident. Many commercially important aquatic species are affected by low
levels of this toxicant (Ludke, et al., 1971; Bookhout and Costlow, 1976;
Lowe, et al., 1971). Even though mirex is very sparingly soluble in
water, the acute toxic levels were generally comparable to concentrations
obtainable through dissolution. Ingestion of the mirex baits (0.3
percent) by aquatic invertebrates has been shown to cause lethal toxic
symptoms in these organisms (Ludke, et al., 1971; Lowe, et al., 1971).
Aquatic invertebrates are the most likely organisms to suffer from
pollution by mirex. Current regulations for use of the pesticide prohibit
its use on aquatic habitats. The levels of mirex found in streams from
areas subjected to aerial application of these baits (0.3 percent) have
been 5 to 100 times less than the levels that laboratory studies have
shown to be acutely toxic.
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The acute toxicity of mirex to fish is very low (Van Valin, et al.,
1968; Hyde, et al., 1974). Levels that did produce toxic effects were
generally many thousands of times the concentration that might be
expected in the environment. For example, the concentrations used by Lee,
et al., (1975); Van Valin, et al., (1968); and de la Cruz and Naqvi,
(1973) ranged from 1000 to 1,000,000 times realistic environmental
concentrations in water.
Birds are even less acutely sensitive to mirex than fish. Dietary LC
CQ values are typically in the range 1500-10,000 mg/kg. No reproductive
effects have been observed with quail, mallard ducks or chickens fed
10-200 mg/kg mirex in their diet.
The acute toxicity of mirex to mammals is relatively low. The oral LD
5Q values for rats are 7^0 mg/kg for males and 600 mg/kg for females. The
acute dermal LD_. is over 2000 mg/kg (Gaines, et al., 1969). A number of
chronic effects have been observed in several mmammalian species. These
include weight loss, increased liver weight, changes in liver function
and structure, and reproductive problems (Gaines and Kimbrough, 1970;
Khera, et al., 1976; Abston and Yarbrough, 1976; Innes, et al., 1969;
Ulland, et al., 1977).
Enzyme inhibition (Hendrickson and Bowden, 1975) and changes in liver
enzyme levels (Abston and Yarbrough, 1976; Baker, et al., 1972) have been
observed. It is not clear, however, what significance these changes have
to the organism. Increases in liver weight and fat inclusion in livers of
mirex-treated animals have been observed (Abston and Yarbrough, 1976;
Kendall, 1974). The distribution of mirex in tissues of rats and monkeys
fed mirex contaminated diets has been investigated (Wiener, et al., 1976;
Pittman, et al., 1976). Most of the residue that is retained accumulates
in the fat. Significant concentrations in liver, kidney and intestine
were also observed. A number of studies of the effect of mirex on
reproduction in mammals have appeared. Reproductive success is impaired
in rats (Gaines and Kimbrough, 1970). Placental transfer of mirex has
been demonstrated (Gaines and Kimbrough, 1970; Khera, et al., 1976).
Survival of offspring was reduced and cataracts developed in suckling
rats from mirex contamination in the mothers milk (Gaines and Kimbrough,
1970). A reproductive study on rats by Khera, et al., (1976) showed that
mirex did not produce significant changes in number of fetal skeletal
anomalies at any level studied but did produce an increased number of
visceral anomalies at the two highest dosages (6.0 and 12.5 mg/kg/dose;
60 and 125 mg/kg total). These levels also caused significant maternal
toxicity. When male rats were treated at 1.5, 3*0 and 6.0 mg/kg/dose;
(15, 30 and 60 mg/kg total) the only significant change was that animals
dosed at 6.0 mg/kg/dose and mated with untreated females produced fewer
pregnancies 0-5 days after dosing.
Two carcinogenicity studies with mirex have been reported. The first
by Innes, et al., (1969) was with mice. This study was designed to be a
preliminary screen for carcinogenicity of a large number of compounds to
identify those compounds that should be subjected to more extensive
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studies. Of the 120 compounds tested, 11 produced significantly more
tumors than controls. Mirex was one of the eleven. There was a single
dosage level for each chemical and for mirex this was 10 mg/kg of body
weight per day from age 7 days to age 4 weeks. After four weeks the
toxicant was added directly to the diet (26 mg/kg). None of the mice on
the mi rex-contaminated test diet survived to the end of the experiment.
Examination of these mice revealed significant increases in hepatomas in
both strains of mice tested and with both males and females. Females were
more susceptible than males. These preliminary data are strongly
indicative that mirex caused hepatic tumors in these strains of mice. No
Judgments were made about whether the observed tumors were malignant or
nonmalignant.
In the second study by Ulland, et al., (1973), it was initially
reported that mirex was not a carcinogen in rats. Later (Ulland, et al.,
1977) this interpretation of the data was changed. In this study 26 rats
in each group (male and female, two dose levels) were fed 40 and 80 mg/kg
for 10-weeks and then 50 and 100 mg/kg for 15-5 months. They were
sacrificed at 24 months. Something apparently happened at about the 70th
week of the experiment because both controls and test animals began to
suffer high death rates. At the end of the experiment 35 percent of the
female controls and 45 percent of the male controls had died. In the test
groups survival was poorer than with the controls, falling to as low as
25 percent survival. There was a high incidence of tumors regardless of
sex or dose but no statistically significant differences (P < 0.05) were
noted with the exception of tumors of the liver. One carcinoma was
detected in the low dose group, five in the high dose group (4 male, 1
female) and none in the control. The differences in this parameter
between test animals and controls were not significant at P <0.05.
Neoplastic nodules were observed (includes the above mentioned
carcinomas), six in the low dose group (2 male, 4 females), eleven in the
high dose group (7 males, 4 females) and none in the control group. Only
the observation of 7 neoplastic nodules in the high dose male rats was
significant at the 0.05 level. This was the only statistically
significant result from the data of this study that indicates that mirex
produces tumors. Although the experimental design and circumstances did
not allow statistically valid conclusions to be drawn from most of these
data, the apparent trend of higher rates of liver alteration, tumors and
carcinomas makes it clear that well-designed studies are needed. A good
summary of the state of knowledge with regard to the carcinogenic
potential of mirex would be that mirex is possibly cancer causing, but
has been neither established as carcinogenic nor proven safe.
8.1.6 Effects on Human Health
There has been no exposure of humans to mirex equivalent to the
Kepone exposure of Life Sciences Products Company employees. Therefore,
no data are available on the toxic effects of mirex to humans. Monitoring
data indicate that humans are exposed to and are acquiring residues of
this compound. The highest level reported was 1.32 ppm in adipose tissue
(Kutz and Strassman, 1976). Acute toxic effects would not be expected to
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be readily apparent from contamination at these levels. Only about ten
years have elapsed since aerial applications were begun and so cancer
epidemiology studies would not yet be expected to reveal if mirex is a
carcinogen in humans. The exposure of human beings to this compound is
not very great and so no group of individuals with significant exposure
to the chemical is available. Some judgments about the effects of this
compound on human health can be drawn from other studies. The potential
for problems clearly exists because mirex is not metabolized by mammals
(Ivie, et al., 1974); it is stored in the fat (Mehendale, et al., 1972)
and is excreted very slowly (Ivie, et al., 1974), therefore, prolonged
exposure even at very low levels could lead to significant body burdens
of the chemical. Residues have been observed in human adipose tissue and
extrapolation of the data of Ivie, et al., (1974) would lead to an intake
of about 0.01 mg/kg to give the equivalent amount of toxicant in a rat.
The studies showing chronic toxic effects have utilized levels from 2500
to 10,000 times this concentration. These studies are indicative that
given sufficient exposure effects on human health may occur. This risk
must be weighed against the human health problems posed by the imported
fire ant. Presently mirex is the only practical toxicant for wide area
treatment of this insect.
8.1.7 Regulations
The established tolerances for mirex are 0.1 ppm (negligible residue)
in the fat of meat of cattle, goats, hogs, horses, poultry and sheep; 0.1
ppm (negligible residue) in milk fats and eggs; and 0.01 ppm (negligible
residue) in or on all other raw agricultural commodities (Code of Federal
Regulations, 1976). These regulations appear to provide adequate
protection of human food supplies.
8.2 ENVIRONMENTAL ASSESSMENT-KEPONE
The registered uses of Kepone do not appear to present a significant
hazard to the environment. That careful control of manufacturing
operations for toxic chemicals is necesssary was painfully illustrated by
the problem created by Life Science Products Company's misuse of this
chemical. It is difficult to make objective judgements about this
compound because of the highly emotional atmosphere that surrounds it.
However, even if it had not been misused by LSPC, the fact remains that
it has been identified as a carcinogen in rats and mice. Human exposure
has been very limited and so the benefits of its household use as an ant
and roach bait must be weighed against the potential accumulation and the
possibility that this could cause cancer in humans. Continued use of
Kepone does not appear to present an environmental hazard if its use is
controlled very carefully.
Residues present in the environment and in human food supplies are a
pressing problem. Ways of decontaminating sediments need to be explored
and careful attention paid to residues in food from these contaminated
areas.
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Kepone was produced by Allied Chemical Corporation and various
contractors from 1951-1975. During this period 1,592,895 kg were produced
(Ferguson, 1975). Almost all of this quantity was manufactured for export
(U.S. Environmental Protection Agency, 1976). Over half of the total
quantity was produced from 1974 through July 1975 (Ferguson, 1975) when
production was terminated. Kepone is no longer being manufactured in the
United States.
8.2.1 Uses for Kepone
The primary uses for Kepone were as a chemical intermediate for
production of an insecticide (Kelevan) in Europe and for direct use in
control of the banana root borer. In the United States the registered
uses have been for wireworm control in tobacco and in 0.125 percent bait
formulations for household control of ants and roaches.
8.2.2 Analysis
The analytical methods for Kepone are similar to the standard
chlorinated hydrocarbon screening procedures (Pesticides Analytical
Manual). Kepone adsorbs strongly to glass and other surfaces. This can
lead to contamination problems (syringes, glassware, etc.) or to losses.
Kepone readily forms a hemiketal with alcohols and so if one introduces
methanol or ethanol into the solutions less problem with adsorption is
encountered and the gas chromatographic behavior is not changed, because
reversion to Kepone occurs in the heated inlet of the gas chromatograph.
Florisil cleanup is not as satisfactory as with less polar compounds
because the more polar eluates also elute many polar interfering
substances. Advantage may be taken of the solubility of Kepone in aqueous
alkali solutions to help remove interferences.
Confirmation by mass spectrometry can be achieved. The ions m/e 270,
272, 274 . . . for 0,-Clg are very intense and their relative intensities
must be in accord ffitn the expected isotopic abundance of chlorine. A
weaker cluster for C,_C1|.0 is also observed.
8.2.3 Environmental Contamination
The only significant source of environmental pollution by Kepone in
the United States has been from facilities producing the technical grade
chemical.
Contamination of the environment does not appear to be a problem when
Kepone is used as prescribed, because the uses authorized for this
compound in the U.S. utilize it in very low concentration in baits and
traps with no broadcast application. The major environmental problems
that Kepone poses are associated with the manufacture of the technical
material.
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The situation that arose at LSPC was hopefully a unique one.
Unauthorized dumping and poor containment of dust and powders in the
manufacture of the compound resulted in air and water pollution of an
unprecedented magnitude. It is unlikely that this will be a recurring
problem but the massive contamination that did occur is likely to remain
as a problem for years because of the environmentally stable nature of
the compound.
Contamination of wildlife, in particular aquatic organisms, appears
in all cases to be associated with manufacture of the pesticide, never
with its normal utilization as a commercial poison. This contamination
must be of particular concern when the organisms are sources of human
food.
Kepone appears to be a very persistent pollutant. Residues have been
detected in biota in 'contaminated ecosystems more than ten years after
the last exposure (Toxic Materials News, 1976). However, Kepone is
chemically reactive. The facile condensation and nucleophilic
displacement involve the gem dihydroxy group, not the chlorinated carbon
skeleton. Kepone may be regenerated by degradation of the compounds that
result from these reactions (Sandrock, et al., 1974). At short
wavelengths, Kepone is more photo chemically reactive than mi rex (Alley,
et al., 1976) and its photochemistry involves reductive dechlorination
(Alley, et al., 1974a)
8.2.4 Bioaccumulation
Aquatic invertebrate species accumulate Kepone efficiently from water
containing this pollutant by factors ranging from 10 to 10,000 (Bahner,
et al., 1976; Hansen, et al., 1976). Aquatic vertebrates also were found
to concentrate Kepone from contaminated water (Bahner, et al., 1976).
Both invertebrate and vertebrate species accumulate Kepone from
contaminated food sources (Bahner, et al., 1976). No data on metabolism
have been reported.
Accumulation of Kepone residues in mice and rats was observed when
this compound was included in their diets. These residues declined
sharply if the animals were removed from the contaminated diet (Huber,
1965). Dairy cattle fed Kepone-contaminated rations produced milk
contaminated with Kepone residues. These residues dropped quickly when a
normal diet was resumed (Smith and Arant, 1967).
It appears that Kepone behaves similarly to the other chlorinated
hydrdocarbons in terms of uptake from a contaminated environment. It does
appear to be much more readily excreted than many of the other members of
this group (Huber, 1965). This is especially evident when Kepone is
compared to mirex. It appears that incorporation of residues can result
both from environmental exposure (air and water) and from contaminated
food sources.
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8.2.5 Nonhuman Toxicology
Laboratory experiments have shown that Kepone is a toxic to
microorganisms (Brown, et al., 1975) and levels from 0.35 to 0.60 ppm
caused a 50 percent reduction in growth of phytoplankton (Walsh, et al.,
1976). Under controlled laboratory conditions, Kepone is very toxic to
some aquatic invertebrates - mysid, 96 hr LC_Q10.1 ppb (Nimmo, et al.,
1976) but less so to some others - blue crao, 96 hr LC^Q 1345 ppb
(Heitmuller, 1975). Toxicity of Kepone to aquatic vertebrates is in this
same range, 48 hr LC5Q 50-100 ppb, (U.S. Environmental Protection Agency,
1976). Concentrations found in contaminated waters have all been under 4
ppb, less than the lowest of these LC^Q values. The higher level in
sediments (up to 30 ppm) from contaminated areas is probably more
significant to the inhabitants of these aquatic ecosystems. No laboratory
studies addressing the question of the effect of contaminated sediments
on these organisms are available. Kepone has not been a pollution problem
outside the aquatic environment except where terrestial species are at
the upper end of aquatic food chains. Birds and mammals are candidates
for this type of exposure. The acute toxicity of Kepone to several
species of birds is low; however, chronic efffects have been noted
(Eroshenko and Wilson, 1974). These included liver enlargement, weight
loss, tumors, changes in the reproductive organs and an "estrogen-like"
effect of the compound. It is likely that carnivorus birds in the
contaminated area will achieve significant residues of Kepone, but it is
unlikely that this exposure will approach the levels used in the
laboratory experiments (50-600 ppm feeding levels).
While the effects of Kepone on mammals are of interest from the
standpoint of survival of wildlife, their primary importance lies in
their relationship to human health. Kepone presents an unusual case. In
addition to the usual experiments with laboratory animals there is also a
human population that has been subjected to high exposure.The human
subjects exhibited symptoms similar to those produced in test animals
subjected to sublethal doses, notably neurological symptoms, tremors,
irritability, weight loss and reproductive failure (Center for Disease
Control, 1976).
Acute toxicity values of Kepone for several mammalian species have
been determined and are in the range 70-250 mg/kg. Thus, Kepone has
moderate acute toxicity compared to other poisons. Chronic toxicity
studies have shown, in addition to those effects listed above, rapid
accumulation of residues followed by relatively rapid loss of residues
after withdrawal from the contaminated diet; reproductive problems-loss
of both male and female fertility, placental transfer, contamination of
milk; teratogenic effects, and increased incidence of oncogenicity and
carcinogenicity in mice and rats (U.S. Dept. HEW, NIH-NCI, 1976). When
compared to pooled controls both male and female rats at the high dose
rate showed statistically significant (P 0.05) increases in
hepatocellular carcinomas.
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Male and female mice showed significant increases at both high and low
dose rates. It is clear from this study that Kepone produced cancer in
both rats and mice fed diets contaminated with 8 to 40 mg/kg of toxicant.
8.2.6 Effects on Human Health
The information available on toxicity of Kepone to humans results
from the Life Sciences Products Company workers who were exposed to
sublethal doses of this chemical. The exposure occurred from 1974 through
1975 and so no information on long term effects such as carcinogenicity,
mutagenicity or teratogenicity can be derived from studies of these
individuals. Some of these people were heavily exposed and suffered
sublethal toxic effects. These included neurological impairment
manifested by tremors, jumpy eye movements, exaggerated startle response
and cerebellar dysfunction (Guzelian, et al., 1975); hepatotoxic
effects-histology showed increased fat, numerous dense bodies and
proliferation of smooth endoplasmic reticlum. These symptoms are not
unexpected from individuals suffering heavy exposure to organochlorine
pesticides. In addition, certain reproductive effects were observed
including decreased fertility manifested by low sperm counts, decreased
motility and increased abnormal forms (Anderson, et al., 1976).
It is unlikely that members of the general public would have
sufficient exposure to suffer from acute Kepone poisoning. Chronic
poisoning from contaminated food could be a problem if careful attention
is not concentrated on residues in food taken from contaminated waters.
8.2.7 Regulations
The Food and Drug Administration has established action levels for
residues of Kepone in fishery products as follows: oysters, clams and
mussels 0.3 ppm; fin fish 0.1 ppm; crabs 0.4 ppm, based on edible portion
in each case. These "action levels" are based on average dietary intake
of the mentioned foods, and appear to provide adequate protection.
228
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