Endrin: Position Document 2/3
Special Pesticide Review Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
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ENDRIN TECHNICAL SUPPQKT TEAM
Kyle Barbefaenn, Project Manager, SPRD, QPP
Mitch Bernstein, Attorney, CGC
William Bumam, Ehaonaoologis t, BED, OPP
David Coppage, Aquatic Biologist, HED, QPP
George Ludvik, Entomologist, BFSD, OPP
Dudley Mattscn, Economist, BFSD, OPP
Gerald O'Mara, Eccncmist, SPED, QPP
David Severn, Chemist, HED, QPP
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Table of Contents
I. Introduction Page
A. Background 1
1. The Statute 1
2. The "RPAR" Process 2
3. Organization of this Position Document 2/3 3
B. Chemical and Physical Characteristics, Registered
Uses, Production, and Tolerances 4
C. Regulatory History 6
II. Risk Analysis 11
A. General Risks and Rebuttals U
1. The Presumption Based cn Acute Dennal Toxicity
a. Basis of the Presumption 11
b. Rebuttals 12
c. EPA1s Response to the Rebuttals 13
2. The Presumption Based on Acute Toxicity to Wildlife 13
a. Basis of the Presumption 13
b. Velsicol's Rebuttal 14
c. EPA's Response to Velsicol's Rebuttal 16
3. The Presumption Based cn Significant Reduction of
Nontarget Populations 18
a. Basis of the Presumption 18
b. Velsicol's Rebuttal 18
c. EPA's Reply to the Rebuttal 19
4. The Presumption Based cn Fatality to
Endangered Species 33
a. Basis of the Presumption 33
b. Velsicol's Rebuttal 34
c. EPA's Reply to the Rebuttal 35
5. The Presumption Based cn Oncogenic Effects 40
a. Basis of the Presumption 40
b. Velsicol's Rebuttal 41
c. EPA's Response to Velsicol's Rebuttal 42
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6. The Presumption Based on Fetotoxic and
Teratogenic Effects 44
a. Basis of the Presumption 44
b. Velsicol's Rebuttal 45
c. EPA's Reply to the Rebuttal 46
B. Other Agency Concerns Relative to Risk frcm Endrin 52
1. Effects of Chrcnic Exposure 52
2 Mutagenicity 53
3. Metabolic Fate in Man 54
C. Risk Assessment of the Major Uses of Endrin 55
1. Cotton 56
2. Small Grains 59
3. Orchards 61
III. Benefit Analysis 63
A. Introduction 63
B. Cotton 64
C. Wheat and Other Snail Grains 84
D. Orchards 88
E. Sugar Cane 92
F. Conifer Seeds 95
IV. Development and Selection of Regulatory Options 97
A. Introduction 97
B. Rationale for the Development of Options 97
C. Velsicol's Risk Reduction Proposals 99
0. Risk Reduction Methods 101
1. Classification for Restricted Use
Limitation of Use of Certified Applicators 103
2. Reduction of Dermal Exposure by Use of
Protective Clothing 105
3. Reduction aŁ Inhalation Exposure by Use
of Respirators 106
4. Reduction of Exposure by Minimization of Drift 106
5. Reduction of Environmental Contamination
by Minimization of Run-Off 108
6. Reduction of Ingestion Exposure 109
E. Regulatory Options Selected U0
1. Continue Registrations as Restricted Use
Pesticides U0
2. Modify Terms, and Conditions of Registrations HI
3. Cancel Registrations 113
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V. Impact of the Major Options 114
A. Introduction 114
B. Investigation of the Impacts of Regulatory
Options for Each use of Endrin 114
1. Cotton 114
2. Small Grains 135
3. Apple Orchards 149
4. Sugarcane 158
5. Ccnifer Seed Treatment 163
6. Watermelon Seed Treatment (Florida Registra-
, ticns) 167
7. Vegetable and Melon Seed Treatment (California) 170
8. Alfalfa and Clover Seed Crops (Colorado) 172
9. Ornamentals 174
10. Tree Paint 177
U. Perch Treatment for Nuisance Birds 178
VI Sunoary of Proposed Courses of Action 185
VH. Bibliography 188
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ENDRIN
I. Introduction
Endrin belongs to the cyclodiene class of chlorinated
hydrocarbon pesticides, and is classed as an insecticide/
rodenticide. It is used mainly in the form of a concentrated
solution which is mixed with water for application primarily
to control insects on cotton and wheat and to control mice
in orchards. Currently, approximately 400,000 pounds are
used on less, than 2 million acres per year. Endrin is the
most acutely toxic of all of the chlorinated hydrocarbons.
Because of endrin's acute toxicity, in 1978, the Agency
classified it as a restricted use pesticide (43 FR 5782).
As a restricted pesticide endrin is available only to
certified applicators.
A. Background
1. The Statute
The Federal Insecticide, Fungicide, and Rodenticide
Act, as amended ("FIFRA") (7 U.S.C. 136 et seq.) regulates
all pesticide products. Section 12(a)(1)(A) of FIFRA requires
all pesticide products to be registered by the Administrator
before they may be sold or distributed. Before the Admini-
strator may register a pesticide, however, he must determine
that its use will not result in "unreasonable adverse
effects on the environment," which is defined by 2(bb) of
FIFRA to mean "any unreasonable risk to man or the environ-
ment, taking into account the economic, social, and environ-
mental costs and benefits of the use of any pesticide."
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In other words, any decision concerning registration must
take into account both the risks and the benefits from the
use of the pesticide.
Section 6(b) of FIFRA authorizes the Administrator
to issue a notice of intent to cancel the registration of
a pesticide or to change its classification if it appears
to him that the pesticide or its labeling "does not comply
with the provisions of [FIFRA] or, when used in accordance
with widespread and commonly recognized practice, generally
causes unreasonable adverse effects on the environment."
Thus the administrator must cancel the registration of a
pesticide whenever he determines that it no longer satisfies
the statutory standard for registration which requires
among other things that the pesticide not cause "unreasonable
adverse effects on the environment'' (Section 3(c)(5). He may
also cancel the registration of a pesticide if its labeling
does not comply with the misbranding provisions of FIFRA
which require the labeling to contain language "adequate to
protect health and the environment" (FIFRA 2(q)).
2. The "RPAR" Process
The Agency has designed a process to gather
risk and benefit information about a problem pesticide and
to make a balanced decision concerning it in an open manner
allowing maximum participation by all interested groups.
This process is known as the Rebuttable Presumption Against
Registration (RPAR) process; it is set out in 40 CFR
Section 162.11.
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In broad summary, these regulations describe the
various criteria for determining that a risk exists, and
provide that a RPAR shall arise if the Agency determines
that any of these criteria have been met. Once the Agency
issues such a rebuttable presumption, the regulations
provide an opportunity for registrants, applicants, and
interested persons to submit evidence to rebut the presump-
tion. These persons may also submit evidence relating to
the economic, social and environmental benefits of any use
of the pesticide. If the presumptions of risk are not
rebutted, the evidence on the benefits of the pesticide
which is submitted to or gathered by the Agency is then
evaluated and considered along with the information on the
risks from the. pesticide. The Agency then analyzes various
methods of reducing the amount of risk from the pesticide
together with their costs and determines whether it can
regulate the pesticide in such a manner so as to strike the
balance between risks and benefits. Striking the balance
may necessitate cancelling certain uses of the pesticide."
3. Organization of This Position Document 2/3
This Position Document 2/3 contains six parts.
Part I is this introductory section. Part II is an evalua-
tion of the risks associated with endrin on which the
RPAR action was based. It includes descriptions of relevant
experiments and field observations, Agency responses to RPAR
rebuttal comments, and the Agency's assessment of those
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risks. Part III is a description of the process which the
Agency employed to gather and to analyze information about
the economic benefits associated with endrin, on a use-by-
use basis. Part IV describes the range of regulatory options
available to the Agency for the reduction of unreasonable
risks, and explains the basis of the Agency's selection of
alternative courses of action for each registered use of
endrin. Part V is the Agency's evaluation of the risks and
benefits associated with endrin on a use-by-use basis,
including an evaluation of the risks associated with sub-
stitute chemicals for endrin, and the Agency's evaluation of
each available regulatory option. The beneficial and
adverse impacts for each alternative course of action are
evaluated, and the rationale for the decision on each use is
set forth. Finally, Part VI summarizes the regulatory
action which the Agency proposes to take, in the aggregate,
concerning the registrations of pesticide products contain-
ing endrin.
B. Chemical and Physical Characteristics, Registered
Uses, Production, and Tolerances
1. Chemical and Physical Characteristics
Endrin (Hexachloroepoxy-octahydro-endo-endo-
dimethanonaphthalene) belongs to the cyclodiene class of
chlorinated chemical pesticides. Endrin is a stereoisomer
of dieldrin. Much like its chemical relatives, it is a
nonpolar compound, slightly soluble in water (230 ug/1 at
25°C), highly soluble in lipids, and it is strongly
adsorbed by organic particulate matter.
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2. Registered Uses
Currently there are a total of 115 EPA-
registered products containing endrin as the active ingre-
dient. They are used primarily for the control of insects
on cotton, small grain crops, sugarcane and ornamentals. In
addition, endrin is registered for use as a ground spray to
control orchard mice, as a perch treatment to control birds
around buildings, and as a conifer seed treatment to repel
mice. There are thirty-six applications for the federal
registration of state-registered products. The state
products are registered for a variety of similar and
additional uses including vegetable and watermelon seed
treatments, alfalfa and clover seed crops and tree paint.
3. Production
The Agency's estimates of the amounts of endrin
used during the past three years on the three crops on which
endrin is most often and most heavily used, differ substantial-
ly from what Velsicol, the major marketer of endrin, is able
to establish from its records. Because the discrepancies
between the two sets of figures are substantial, the Agency
requested Velsicol to disclose its estimates of the amounts
of endrin which were sold for use on these crops during the
years 1975-1978. These amounts are in thousands of pounds of
endrin as active ingredient (a.i.) (Ebner, 1978).
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1375
197S
1977
1978 (est.)^
Cotton
1,200
355
360
280
Small grains
140
201
25
31
Orchards
61
90
64
81
All other uses of endrin combined probably amount to less
than 10,000 lbs. endrin a.i.
4. Tolerances
In 1966, the FDA established tolerances of
zero for residues of endrin in or on the following raw
agricultural commodities: broccoli, brussels sprouts,
cabbage, cauliflower, cottonseed, cucumbers, eggplant,
peppers, potatoes, sugar beets, sugarbeet tops, summer
squash, and tomatoes (31 FR 13210; 10-13-66). Current
Agency policy requires that tolerances higher than zero
be established for the pesticide residues which result from
the use of the pesticide in or on current food and feed
commodities. If, as a result of the RPAR process, CPA regis-
ters endrin for use on certain food and feed commodities,
the Registration Division will establish the actual tolerances
when the Agency has completed the RPAR review.
C. Regulatory History
The history of the federal regulation of the pesti-
cide, endrin, is composed of a series of official notices of
actions which the federal government has taken in its
efforts to restrict the use of the pesticide, as well as the
response to those actions by interested members of the
public.
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Endrin has been used as a pesticide in the United
States since 1951. Serious concern over the impacts on
the environment from endrin can be traced to the massive
fish kills which occurred in the lower Mississippi River
during the early 1960's. In 1969, the Report of the Secre-
tary of Health, Education, and Welfare's Commission on
Pesticides and Their Relationship to Environmental Health
(Mrak, 1969) listed endrin among several pesticides which
"are persistent and cause or can cause contamination of the
environment and damage to various life forms within it."
The Commission recommended that the use of these persistent
pesticides be restricted "to specific essential uses which
create no known hazard to human health or to'the quality of
the environment." (Recommendation 4, p. 9.) Before the
formation of EPA, the USDA cancelled the use of endrin on
alfalfa, eggplant, lettuce, peppers, tomatoes and strawberries
in February 1968 (Pesticide and Registration Notice 68-6).
EPA cancelled its use on corn, potatoes, sorghum and sugar
beets in March 1971 (Pesticide Registration Notice 71-3).
Public comment on the risks and benefits of the use
of endrin was solicited by the Agency in a March 18, 1971,
Federal Register Notice. After completing an internal
review, Agency scientists recommended that the Agency cancel
the registration of endrin for use on all commodities except
for the use on conifer seeds, use on small grains to control
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pale western cutworms, the use of bird perches to control
nuisance bird and the use in orchards to control orchard
mice, because of the concerns these scientists had about the
adverse effects of endrin on fish and wildlife.
On July 31, 1975, the Environmental Defense Fund
and the National Audubon Society petitioned the Agency to
suspend or cancel all uses of endrin. Velsicol Chemical
Corporation responded to this petition on November 10, 1975.
On April 30, 1976, the Environmental Defense Fund renewed
its petition.
In 1975, EPA initiated an update of the ecologi-
cal hazards of endrin. The Agency received reports that the
deaths of brown pelicans in Louisiana were linked to the use
of endrin. The Agency consulted with the Louisiana State
University, the Louisiana State Wildlife and Fisheries
Commission, and the Patuxent Wildlife Research Center
concerning the deaths of the brown pelicans and obtained
copies of autopsy and residue analyses.
In accordance with Section 7 of the Endangered
Species Act of 1973 (50 CFR 402, 43 FR 870), the Agency
requested formal consultation with the U.S. Fish and
Wildlife Service (Dreer, October 17, 1977) regarding
the potential threat of endrin to endangered species.
Their response was received on June 8, 1978 (Greenwalt,
1978). The U.S. Fish and Wildlife Service has also supplied
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the Agency with reports of recent tests -which were conducted
in collaboration with the U.S. Forest Service in order
to evaluate the hazards of endrin-treated conifer seeds to
birds.
On May 19, 1977, the Agency held public hearings
under FIFRA Section 21(b) in New Paltz, New York and received
verbal and/or written testimony from 37 witnesses represent-
ing 8 states regarding the use of endrin to control orchard
mice (EPA, 1977) . This hearing was preceded by field trips
to inspect damage caused by pine voles in several orchards
and to discuss the problem with growers. Immediately
following this hearing, a group of state officials, exten-
sion workers and researchers met informally with represen-
tatives of the Agency to discuss possible ways of reducing
the risks associated with the use of endrin to control
orchard mice. Agency personnel have also participated in
both the First and the Second Eastern Pine and Meadow Vole
Symposia (Byers 1977, 1978). These opportunities to discuss
the orchard mouse problem with a wide variety of knowledge-
able and concerned people have been supplemented by many
phone calls and a large amount of correspondence between the
Agency and experts on the subject.
On May 26, 1977, the Agency held public hearings
under 21(b) of FIFRA in Kansas City specifically for the
purpose of soliciting suggestions and recommendations from
users, state extension workers, and others on steps that
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could be taken to reduce the risks associated with the use
of endrin to control the pale western and army cutworms on
wheat and other small grains. Testimony was received from
26 witnesses representing 4 states (EPA, 1978).
On December 8 and 9, 1977, Velsicol convened a panel
consisting of experts on the aerial application of pesticides
and on the use of endrin on cotton and wheat, to develop
recommendations for reducing the risk associated with the
application of endrin (Akesson, 1977). The Agency was
invited to participate as observers in the proceedings.
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II. Risk Analysis
The Agency presumed in endrin Position Document #1 that
pesticide products containing endrin meet or exceed the
following six criteria for risk which are delineated in 4Q
CFR 162.11: 1) oncogenicity, 2) fetotoxic and teratogenic
effects, 3) fatalities to an endangered species, 4) signifi-
cant population reductions in nontarget organisms, 5) acute
toxicity to wildlife, and 6) acute hazards to humans and
domestic animals through dermal exposure and published
a notice of these findings in a Notice of Rebuttable Presump-
tion Against Registration (41 FR 31316, July 27, 1976). In
the notice, registrants and other concerned parties were
advised of the opportunity to submit information or comments
either in rebuttal of, or in support of, the presumption, as
well as information concerning the benefits of endrin. The
Agency has received submissions from 70 parties in response
to the RPAR notice.
A. General Risks and Rebuttals
1. The Presumption Based on Acute Dermal
Toxicity
a. Basis of the Presumption
While conducting the review of the literature
on endrin, an Agency scientist discovered an unpublished
dissertation which reported the existence of two formulations
which exceeded the criterion for the risk of dermal toxicity
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as stated in 40 CFR Sec. 162.11(a)(3){i)(A). Because the
existence of the formulations was reported in two unpublished
reports, the Agency did not find it possible to identify the
producer of the two formulations. The Agency therefore
directed all registrants to certify whether or not their
particular formulations met or exceeded this criterion
for risk. Velsicol Chemical Corporation (Calo, 1976) and
Rid-a-Bird Corporation (Bosch, 1976) submitted the only
responses to this directive.
b. Rebuttals
(1) Velsicol's Rebuttal
Velsicol submitted test data for three (3)
formulations: an emul3ifiable concentrate (EC) containing
1.6 pounds of endrin per gallon, an EC containing 1.6 pounds
each endrin and methyl parathion per gallon, and an EC
containing 2.4 pounds endrin per gallon (Calo, 1976}.
The Agency evaluated the test results and determined that
the test protocols met acceptable testing standards, and
that the results indicated that all the formulations fell
below the criteria for risk for both inhalation and dermal
toxicity (Butler, 1977).
(2) Rid-A-Bird'3 Rebuttal
The data submitted by Rid-a-Bird on its 9.6% EC
formulation were consistent with those which Velsicol sub-
mitted, and the Agency judged the results to be adequate
evidence that this formulation did not exceed these criteria
for risk (Burnam, 1977).
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c. SPA's Response to the Rebuttals
The Agency has accepted the rebuttals by Velsicol
and Rid-a-Bird. Since no other registrants submitted rebut-
tals, and since many formulations of endrin may contain
toxic and/or inert ingredients which are not present in the
formulations tested by Velsicol and Rid-a-Bird, the Agency
will deny the applications of other registrants for the
registration and reregistration of endrin products unless
they can demonstrate that their formulations do not meet or
exceed the criteria for risk of dermal toxicity.
2. The Presumption Baaed on Acute Toxicity to Wildlife
a. Basis of the Presumption
The Agency's presumption was based on theoretical
calculations of the endrin residues that could be expected
to occur On wheat (0.25 lb/acre) and on forage and seeds in
orchards treated with a ground spray (1.2 lb/acre) to
control meadow mice. The amounts of endrin residues which
SPA scientists estimated would occur in orchards {290 ppm
on short grass, 145 ppm on forage) greatly exceeded the
LDgg (7 mg/Jeg) for rabbits that consume contaminated feed
while residues on seeds approximated the LC5Q for pheasants
(14 ppm). Their estimate of the amount of endrin residues
which they expected to find on wheat exceeded the amount
that would produce an in rabbits (EPA, 1976).
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b. Velsicol's Rebuttal
(1) Hazards from Cotton Use
Velsicol (1976) argued that the use of endrin
probably poses little risk to rabbits, quail, and pheasants
because quail would probably Łeed on the cotton plants only
when the plants are young, before endrin is applied, and the
dense upper foliage of mature plants would reduce the
amounts that would be found at ground level where rabbits
would feed. Velsicol stated that pheasants are not found in
the regions of the United States where cotton is grown.
(2) Hazards from Small Grain Use
In reviewing its files on the residues of endrin
which are found on small grains, Velsicol found that the
highest residue after one day's treatment with 0.25 lb/acre
(the maximum rate oŁ use registered) was 13 ppm. Most
values were lower. Velsicol calculated that if a rabbit ate
about 20% of its body weight in fresh forage it would ingest
2.6 mg/kg/day, an amount well below the for rabbits.
(3) Hazards from Orchard Use
(a) Rabbits
Velsicol (1976) submitted data in which the actual
residues of endrin (1.2 lb/acre) which had been sprayed
in apple orchards were measured. Velsicol determined the
mean of the reported residues as 131 ppm, a value of roughly
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the same magnitude as the theoretical amount estimated by
the Agency. In addition Velsicol cited a report by Treon
in which the LDjg for rabbits was found to be 7 to
10 mg/kg and a report by Pimentel that gives the LD^g as 5
to 10 mg/kg. Velsicol assumed, therefore that the LD^g
could be 8 mg/kg. It calculated that if a 2 kg rabbit ate
nothing but treated grasses (60 g food per day) containing
the mean residue of 131 ppm, it would ingest endrin at a
rate of 3.94 mg/kg/day and thus consume the LD^g after 2
days. However, Velsicol stated that the rabbits' diet is
unlikely to consist of only grasses and that endrin is
rapidly metabolized and excreted. On the basis of these
assumptions/ Velsicol concluded that the rabbit would not
ingest the total amount calculated and, because "sequential
doses are not additive", it would be unlikely that concentra-
tions of endrin in the tissues would approach the range of
the LD50.
(b) Quail and Pheasants
Velsicol noted that the subacute dietary LC^g
value cited in the RPAR for quail and pheasants (14 ppm) was
calculated for young birds and that the LC50 for mature
birds would be much higher. Furthermore, Velsicol assumed
that because endrin is not applied to orchards from late
spring to early fall when these birds reproduce, it is
likely that the birds actually exposed to endrin are mature
birds. Velsicol further assumed that the diets of quail and
pheasants would include other untreated foods.
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c. EPA's Response to Velsicol's Rebuttal
(1) Hazards from Cotton Use
Velsicol states that "endrin is normally applied
when the cotton plant is nearing maturity". However, endrin
is used to control many insect pests on cotton, and many
registrations specify early, mid-season, and later use.
Cotton may be treated as many as 15 times over a 3-month
period, and Velsicol's data indicates that residues on
cotton foliage treated with 0.5 or 1.0 pounds of active
ingredient per acre are 40 to 98 ppm and 100 to 160 ppm,
respectively. By extrapolation, residues from the usual
rate of treatment of 0.4 lb/acre would range from 30 to 80
ppm. Such residues exceed the LC^q for quail (14 ppm),
therefore, the Agency cannot accept Velsicol's rebuttal.
(2) Hazards from Small Grain Use
Velsicol's analysis of the possible effects on
rabbits appears to present a valid argument that the
potential hazard to this species will be low. While some
mortality of rabbits and other wildlife species has been
observed in association with the use of endrin to control
cutworms on wheat (Bushong, 1978a; McEwen, 1978), this
observation alone does not satisfy the criterion for risk.
Thus, the Agency concludes that Velsicol has adequately
rebutted the presumption for this criterion of risk in so
far as the Agency's concern in Position Document 1 focussed
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on residues on the wheat plant. As is discussed below, the
Agency has additional concerns in regard to the residues oŁ
endrin which occur on the insects inhabiting grain fields
which wildlife might eat.
(3) Hazards from Orchard Use
(a) Rabbits
Velsicol's rebuttal is rejected because they used
incorrect values and assumptions. Velsicol (1976) assumed
that a 2 kg. rabbit would consume approximately 60 g of
food per day but this value represents the amount of dry
laboratory chow a rabbit would eat, not the amount of grass
and forage. Velsicol also assumed that the rabbit would
consume a high percentage of materials other than grass, but
Velsicol failed to account for the fact that other materials
which may be fed upon in the treated orchard would also be
contaminated with endrin residues. Moreover, Velsicol's
calculations focus on an application rate of 1.2 lb/acre
(primarily in Washington State), whereas the normal applica-
tion rate for pine voles in the Eastern U.S. is 2.4 lb/acre.
Velsicol's contention that endrin is rapidly metabolized and
excreted by animals and that, therefore, doses are not
cumulative is not supported by the results of an Agency
study in which the acute oral LD^q for endrin in hamsters
was found to be IS mg/kg, whereas that for multiple dosing
was below 1.5 mg/kg (Chernoff, 1978).
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(b) Quail and Pheasants
Velsicol's rebuttal is rejected because it
presents no evidence to support its assumption that the
LC^q of endrin for mature birds is substantially higher
than that for young birds. Furthermore/ although Velsicol
states that the birds will eat foods other than treated
grasses, they do not specify what foods these are, nor do
they show why these foods from a treated orchard would not
be similarly contaminated with endrin.
3» The Presumption Based on Significant Reduction
of Nontarget Populations
a. Basis of the Presumption
The basis for the presumption against endrin for
the reduction oŁ nontarget populations was information on
fish kills derived from the Pesticide Episode Reporting
System (PERS) which implicated endrin in 52 fish and wildlife
kills. Analyses of the residues of endrin which were found
in 33 of these kills supported this body of data.
b. Velsicol's Rebuttal
Velsicol's rebuttal (1976) contended that the
Agency's evaluation of PERS records dealing with fish were
numercially inaccurate, the evidence was too sketchy, other
toxicants were involved, and that whatever kills may be
attributed to endrin were a result of misuse.
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c. The Agency's Reply to the Rebuttal
Velsicol has responded to the Agency's concerns
about reductions in the populations of non-target organisms
which are a result of the use of endrin, by contending
that the information contained in the PERS is inadequate,
and by asserting that the Agency had substantially over-
stated the number of dead fish involved in the incidents
reported.
The Agency is aware that the body of data
in the PERS reports is incomplete. The body of data is
sufficient, however, to indicate endrin's role in causing
fish Kills. The Agency does not allocate a significant
amount of resources for monitoring the'applications of
pesticides in order to ascertain their potential impacts on
fish and wildlife kills nor for the investigation of all of
the reported incidents of fish or wildlife kills. Rather,
the Agency relies on voluntary reporting by private parties
to either state agencies or to the EPA concerning observed
pesticide-related kills. Under such a system, only a
nominal amount of the total number of incidents could be
expected to be both observed and reported to either state or
federal athorities. Moreover, even when incidents are
reported, resources are not always available at either the
state or federal level to measure the concentrations of the
toxicants in water, or to determine the concentrations of
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the residues of the pesticide in the dead fish. Finally, the
PERS system does not include all of the incidents which are
reported at the state level. A rebuttal comment acknow-
ledged that in the State of Mississippi alone at least
twenty endrin-related fish kills had.occurred in five years.
(Young, 1976); none of these incidents were included in the
Agency's PERS files. In light of the acknowledged incomplete
nature of the PERS system, even a few reports of substantial
fish kills are of serious concern to the Agency.
Velsicol's rebuttal disputed the accuracy of the
number of dead fish (31 million) which Position Document 1
attributed to endrin-related fish kills. The Agency is not
as concerned with the overall body count of dead fish as it
is with the water concentrations of endrin which are asso-
ciated with the reported kills. Thus, while Velsicol is
correct in its assertion that the total of 31 million dead
fish reported in Position Document 1 was arithmetically
inaccurate, the Agency's position that endrin causes signfi-
cant reductions in nontarget populations remains unrebutted.
The Agency realistically can never expect to get an accurate
count of the number of fish killed by any or all pesticides;
body counts are often inaccurate, especially when they
range into the millions. Other factors may also complicate
these counts, such as dead fish not surfacing immediately,
or fish dying over a period of several days or even weeks
from a single pesticide episode.
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The relevant focus for assessing the hazards to non-
target organisms associated with the use of endrin is
the occurrence of toxic and lethal concentrations of endrin
in bodies of water where fish kills have been observed.
In order to sustain the criterion for risk set forth in
40 CFR 162.11(a)(3)(ii)(C), the Agency need only establish
a data base where concentrations of the pesticide in the
water associated with fish kills exceed the toxic level
for the sensitive species. To the extent that these
concentrations result from practices of application which
are typical, the Agency may then generalize to the broader
picture oŁ the pesticide's overall use in a given region,
and' can reasonably anticipate that the use will result
in significant local or regional reductions in the popula-
tions of non-target organisms.
Velsicol also attempted to rebut the criterion of risk
by contending that in several of the reported episodes,
other pesticides were present in varying concentrations, and
may have been a substantial contributing factor to the
fatalities. Indeed,. Velsicol attaches considerable signifi-
cance to the fact that the concentrations of other materials
may have been sufficient to cause mortality by their presence
alone, so that it would not be possible to say with any
certainty that endrin alone caused the resulting kill. Once
again, Velsicol's emphasis has been misplaced. The presence
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of lethal concentrations of endrin, which could have caused
the reported kills, is a sufficient basis for the Agency's
concerns about endrin; the presence of lethal concentrations
of other pesticides does not mitigate that concern, but
gives rise to similar concerns about the other chemicals.
To argue that the presence of lethal concentrations of two
pesticides tends to exonerate both rather than to condemn
either is cynical at best.
The Agency has evidence that lethal concentrations of
endrin in water have been associated with reported fish
kills. For example, in the Lake Bartholomew Bayou area of
Louisiana (Incident #1, Table 1) fish (9 samples) sampled
for 21 days contained concentrations of endrin ranging
from 42-445 ug/kg, which clearly demonstrates that they were
exposed to endrin. Water (6 samples) sampled in the area for
19 days had concentrations of 0.1-2 ug/1. All of these
water samples exceeded the 96-hour LC^q's of 0.037
ug/1 for pink shrimp (Penaeus duorarum) and 0.094 ug/1 for
striped bass (Morone saxatilis), and two exceeded the
96-hour LC^q for bluegill (Lepomis macrochirus) of 0.6
ug/1. These concentrations may also be toxic to many other
indigenous species for which a body of toxicity data is not
available. The fish kills in the Lake Bartholomew Bayou
area, which are reported to exceed 7 million fish, occurred
during and following rainfall totalling 7.64 inches over a
one-month period on the cotton field watershed of the area.
-22-
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TABLE 1
ENDRIN RELATED FISH KILLS WHERE WATER (XNCINIRATIONS EXCEEDED LETHAL LEVELS
Incident
number
Estiuated U
fish killed
Date
Location
Type of incident
Endrin in
water (pg/l)
Endrin in
fish (pg/kg)
Data source
No. 1
Greater than
7,000,000
9/1/74 Lake Barth- Cottonfield watershed
9/21/74 olomew Bayou runoff from 7.64 inches
area, Ouachita- rain- 01574-9/15/74
Morehouse
Parrish line,
Louisiana
I
fij
i
Bartholomew
Bayou 9/5/74
0.2 147
Adjacent ditch
9/13/74
2.0 277
La Fouche Canal
9/1/74
0.6
Sandy Bayou
9/16/74
Joe Bayou
9/17/74
0.5
299
445
351
PERS A0084
Louisiana Wildlife
and Fisheries
Commission Report
on Fish Kills, NE
LA, Fall 1974,
by L.R.C. Johnson
Beouf River
9/17/74
Bayou Barthol.
Cutoff 9/19/74
0.1
Tensas River
9/19/74
0.2
9/21/74
353
336
Little Lake
La Fouche 9/19/74
42
49
No. 2 Greater than 7/24/75 Donnegan Cottonfield watershed Eight samples PERS tf 00245
48,000 of 20 Slough, runoff from more than less than 0.1-
species Colbert Co., 8 inch rain over 20 days 2.7
A 1 hhnin^
-------
TABUi 1 (Continued)
No. 3 Largemouth bass 368 9/12/?U
Bluegill ?500
White crappie 350
Channel catfish 900
Yellow
bullhead 150
Drum 3fl0
Carp 18
Blacktail
redhouraa 600
Spotted gar 2
Gizzard shad 3312
Slough of
Black Warrior
River, Old
Lock #?» Hale
Co., Alabama
Cottonfield watershed
1 mile from field
toy.
I
hJ
it-
Yellow bullhead 25 9/l5/?^
Channel catfish *»50
Gizzard shad 550
Minnows 1869
Bream Iff?
Suckers 150
Largemouth bass 25
Mulberry Pork, Cottonfield watershed
Black Warrior runoff from daily
fllver, Cullnan showers for 1 week
Co., Alabama
0.22
Upstream1
less than 0.01
Hidslough;
3.73
Rearslough1
3.36
PERS #002^3
0.18 and
0.22<*
PERS it A0237
-------
TABLE 1 (Continued)
Incident ft Estimated tt Date Location Type of Incident Endrin in Endrin in Data Source
Fish killed Hater (pg/l) Fish (pg/kg)
Ho. 5
Ho. 6
Mo. 7
No. 8
i
N>
in
I
Ho. 9
31
Largemouth bass 9/3/?4
Bluegill
Crappie
Channel catfish
Suckers
North River,
Tuscaloosa
Co., Alabama
Cottonfield
watershed runoff
0.06 and
0.3?
Not given
8/72 Morgan Co., Cottonfield watershed 0.24
Alabama runoff
Largemouth bass 8/17/74
Bluegill
17 other fish
species with
total of 858
killed
largemouth bass 6
Bluogill 506
Yellow bass 198
White crappie 88
Blue catfish 88
Drum
Skipjack
Spotted
redhorse
Smallmouth
buffalo
Carp
Thread fin
shad
Minnows
47 includes
Largemouth bass
Bluegill
Yellow bullhead
Carp
Suckers
Minnows
McKeman
Creek,
Colbert Co,,
Alabama
Cottonfield watershed 0.74
runoff
8/9/74 Limestone
Creek,
Limestone
Alabama
Cottonfield
runoff
watershed 0.3
Co.,
6204
110
hh
22
88
10472
2046
8/20/74 Big German
Creek, Hale
Co. Alabama
Cottonfield watershed
runoff
Trace-
0.168 in
3 samples
PERS #AO244
90 in
Carp
PERS ({<93016
PERS # A0293
6 in
Buffalofish
150 in
Carp
8 in
Bluefin
40 in
Blue catfish
PERS # AO240
210 in
Carp
PERS IA0242
-------
TABLE 1 (Continued)
Uo. 10 30,000 8/3/74 Alabama Stream adjacent to
cottonfieUwatershed
with frequent rain
during week of kill;
10 miles of stream
observed affected
No. 11
70,000
8/20/74 Alabama
Runoff from cottonfield
into stream
i
K>
at
I
Two samples PIMS Summary
0.22
Two samples Catfish PIMS Summary
0.022 and 110
0.65
-------
Incident Estimated if Date Location
number fish killed
No. 12 Unknown do. 11/21/70- North
Bluegill 3/2071 Carolina,
Carp (minimum) Haywood Co.,
Golden shiner
Goldfish
Hogchoker
White sucker
Channel catfish
Bullhead
<
to
-4
I
No. 13
9,300
12/71
Pennsylvania
TABLE Ł (Continued)
Type of Incident Endrin in Ehdrin in Source of
water (pg/1) fish (pg/k^J Data
Apple orchard watershed
in Lake Junaluska area,
received "heavy rain"
11/20/70
Tributary draining
orchard watershed into
river Where fish died
Racoon Creek
11/21/70
0.12
Richland Creek
11/21/70
0.45
11/22/70
0.85
12/3/70
0.5
12/15/70
0.16-0.45
Lakd Jtmaluska
12/23/70
0.39-0.7
450-666 ng/kg in mud 12/15/70)
550
12/15/70 Hater Quality
Kidney Division, Dept.
1,100 of Water and
livfir Air Resources,
3,300 Raleigh, H.C.
Flesh
1,162
PIMS Summary
-------
The occurrence of the heavy rainall following the application
of endrin, and the resultant concentrations of endrin in
water together with the observed fish kills, leads the
Agency to reasonably conclude that run-off from the treated
cotton fields was the source of the contamination by endrin.
Incident Number 2 (Table 1) in Oonnegan Slough, Alabama
followed 8 inches of rain over a 20 day period in an area
where endrin had been applied to cotton. The concentrations
of endrin in 8 samples of water ranged from less than
0.1 to 2.7 ug/1. The higher concentrations exceed the
LC^q values for the above species and it was estimated
that 48,300 fish of 20 species died. Again, the Agency
has concluded that the kills and the associated concentration
of endrin in water were the result of run-off from treated
cotton fields.
Incident Number 3 (Table 1) occurred in a slough of
the Black Warrior River, Alabama, which was one mile from a
cotton field where endrin had been applied. The concentra-
tions of endrin in water ranged up to 3.73 ug/1, which is
far in excess of the of the above aquatic species, and
dead fish of at least 10 species were estimated to number
in the thousands. Further, incident Number 4 (Table 1) in a
fork of the Black Warrior River, Alabama was associated with
run-off from cotton fields treated with endrin following
daily rainfall for one week. Concentrations of endrin
in water were reported as 0.18 and 0.224 ug/1 which exceeds
the LC^q values for shrimp and striped bass.
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In addition to the above incidents, seven other inci-
dents (Incident nubmers 5-11, Table 2) were associated with
run-off of endrin from cotton fields where concentrations of
endrin in the water exceeded values for aquatic
organisms. Maximum concentrations of endrin in ug/1 reported
in water were 0.168, 0.22, 0.24, 0.3, 0.37, 0.65 and 0.74,
all of which exceeded the LC5Q for some aquatic species.
Velsicol contends that the PERS-reported kills "appa-
rently arose from aerial spraying" and that "overspray and
wind drift were apparently the major causes of the aerial
problems"; its expert, Mr. Odom, acknowledges in a footnote
that "run-off may have been a contributing factor." Although
the Agency agrees that drift and overspray are potential
sources of endrin contamination, the Agency's analysis of
the available data leads it to conclude that run-off is a
major factor—not merely a "contributing factor" — in
contamination of water at concentrations lethal to aquatic
life.
This interpretation of the available data is further
supported by models of run-off potential for endrin. The
EPA Environmental Research Laboratory, Athens, Georgia
(Bailey 1975) has modeled or simulated run-off of endrin on
a Piedmont watershed under a number of different expected
rainfall conditions. For example, at the lowest assumed
rainfall rate of 1.44 inches per hour occurring once in a
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year, and assuming a single application of endrin to
cotton of 0.7 lbs/A, run-off was predicted to contain endrin
in amounts of 30 ug/1 (far in excess of LC5Q values for
aquatic organisms even after many-fold dilution). An
additional 0.02 lb/A of endrin was predicted to be carried
off on sediment for a total loss to waterways of 3.77% of
the endrin applied. Although the application was made at a
rate in excess of the rate specified on the label, the
Agency believes that the model provides a sound basis for
its conclusion concerning the high run-off potential of
endrin.
Additional support for the conclusion that concentra-
tions of endrin lethal to aquatic organisms are likely to
occur from run-off may be found in a study of experimental
sugarcane plots. Run-off was measured for endrin (formulated
as 2% active ingredient on 40/60 mesh montmorillonite
granules) after application to the surface of experimental
plots of sugarcane in Louisiana at a rate of 0.337 kg
a.i./hectare. There were 14 run-off events during 10 months
following application with amounts of rainfall varying from
0.53 to 11.43 cm. per rainfall. Runoff waters had maximum
endrin concentrations ranging from 0.12-2.73 ug/1 following
a single application and concentrations in run-off as
great as 1.12 ug/1 occurred as long as two months after
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application. A separate part of the study involved four
run-off events in one month (rainfall was 3.15-9.32 cm) and
showed maximum concentrations of endrin per run-off to be
2.88-5.02 ug/1. Concentrations as great as 4.09 ug/1
occurred as long as one month after application (Willis and
Hamilton, 1973).
Because of land configurations and precipitation
patterns, the area where endrin is applied to cotton exists
among the areas with the highest direct run-off potential in
the United States (Stewart, 1975). Many of the reported
fish kills detailed above occurred after period of rainfall,
and heavy rainfall may be expected to occur throughout the
season when endrin is applied to cotton. The Agency con-
cludes that, wholly apart from drift considerations, the use
of endrin on cotton can reasonably be anticipated to result
in concentrations of endrin in water that exceed the LCgg
of aquatic organisms and can reasonably be anticipated to
result in significant local or regional reductions in the
populations of non-target organisms.
Velsicol contends that fish kills which are the result
of the run-off of endrin from treated fields must be charac-
terized as the result of pesticide misuse, since Velsicol's
endrin lables include the prohibition: "Do not apply where
run-off is likely to occur." The Agency concludes that the
typical application of endrin for use on cotton cannot be
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made in accordance with the directions on the label because
the run-off of endrin from cotton fields always is likely
to occur under the geographic and climatic conditions of
current usage. Moreover, since the run-off has been demon-
strated to result in concentrations of endrin in water
which are lethal to aquatic organisms, the Agency concludes
that application of endrin to cotton in accordance with
widespread and commonly recognized practice can reasonably
be anticipated to result in significant local or regional
reductions in the populations of non-target organisms.
The Agency also has evidence that lethal concentrations
of endrin associated with fish kills occurred as the result
of run-off from apple orchards treated with endrin to
control voles. Several such incidents are summarized in
Table 3. With respect to the Lake Junaluska incident, the
North Carolina Department of Water and Air Resources (1971)
concluded that:
"the Lake Junaluska Fish Kill, which was reported
on November 21, 1970, was caused by a chlorinated
hydrocarbon insecticide known as Endrin. Endrin, used
for rodent control by some of the apple growers in the
Lake Junaluska drainage basin just a few days before
the kill, was washed into Richland Creek by a heavy
rain early on the morning of November 20, 1970. The
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Endrin entering Lake Junaluska from Richland Creek was
reponsible for the initial and continued fish mortalities
that occurred from November 21, 1970, to the latter
part of March 1971."
That incident resulted in lethal concentrations of
endrin in the orchard drainage waters for a period of at
least 33 days, and fish kills continued to be reported
over an even longer period.
The Agency therefore concludes that the use of endrin
on apple orchards also has the potential for causing signifi-
cant local or regional reductions in the populations of
non-target organisms. However, because of significant
variations in rainfall patterns and terrain among the apple
growing regions where endrin is used, the Agency is not
presently able to make any generalizations concerning
reductions in the populations oŁ non-target organisms
resulting from use of endrin on apple orchards.
4. Presumption Based on Fatality to Endangered Species
a. Basis of the Presumption
The brown pelican is classified as an endangered
species by the Office of Endangered Species, D.S. Fish and
Wildlife Service (FWS). For several years, the State of
Louisiana has been attempting to re-establish the species in
that state by transplanting pelicans from Florida to Barataria
Bay, Louisiana. In 1975, scientists observed a substantial
-33-
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decrease in the new population and found several dead brown
pelicans. The Feed and Fertilizer Laboratory at Louisiana
State University and the Patuxent Wildlife Research Center
conducted analyses for residues of endrin; both identified
endrin in the brains of these pelicans in concentrations
ranging from 0.18 ppm to 0.70 ppm. Because the range of the
concentrations of endrin found in the brains of these
pelicans overlapped the range which the Patuxent Wildlife
Research Center found to be lethal in small numbers of a
variety of other birds which they tested, the Agency con-
cluded that contamination by endrin was the major cause of
the decline in the population of the brown pelican.
b. Velsicol's Rebuttal
In its rebuttal, Velsicol characterized the
incident as "small, isolated, and one-time." It argued
that the analyses had not directly established the concen-
tration of endrin which is lethal in brown pelicans, and
that the Patuxent data on residues was gathered from too
small a number of birds to be a reliable basis for prediction.
Velsicol further argued that the brown pelican mortality was
associated with environmental factors such as the presence
of parasites in the birds, and muddy water, which would have
impaired their fishing ability. Velsicol says that these
factors pointed to causes other than poisoning by endrin for
the deaths of the pelicans.
-34-
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c. EPA's Reply to the Rebuttal
With respect to Velsicol's contention that the
incident was "small, isolated and one-time," the Agency
(Markley 1977) determined that this characterization was
both inaccurate and irrelevant, for several reasons.
First, although some media accounts of total brown pelican
mortality were exaggerated due to conflicting reports,
a substantial loss did occur, and was not necessarily
limited to the actual numbers of birds found dead. Moreover,
any contention that the mortality was "isolated1* or a
"one-time" event is pure speculation. The odds of finding a
dead pelican in the wild are remote and, simply because no
major mortality has been observed since 1975, these are no
grounds to conclude that no other deaths have occurred and
that there is no potential for further death.
Velsicol is correct in its contention that the
lethal concentration of endrin in the brains of brown
pelicans has not been established. However, as with humans,
it is necessary to extrapolate the probable risks from a
pesticide from the effects which are observed on less
valuable species. When the RPAR Notice was issued, the
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only available experimental evidence concerning lethal
concentrations of residues oŁ endrin had been derived
primarily from a small study of secondary poisoning in
raptors conducted at the Patuxent Wildlife Research Center
(PWRC). The raptors were fed mice which had been treated
with endrin. Since rats metabolize endrin into a more toxic
product, 12-ketoendrin (Bedford, 1975), it is probable that the
mice which the raptors ate contained the metabolite. To the
extent that 12-ketoendrin was present, it could have caused
the amount of endrin in the brains of the raptors at the
time of death to be lower than it would have been from
exposure to endrin alone. The raptors were not analyzed for
12-ketoendrin. Thus, the standard which the Agency employed
to assess lethal brain concentration was probably faulty.
Velsicol correctly contends that the death
of the brown pelicans in Louisiana was associated both with
the presence of parasites and with muddy water. However, it
also contends that the presence of little or no stored fat
in the bodies of two autopsied pelicans, the fact that their
stomachs were empty, and the presence of parasites all
support the conclusion that "there is considerable evidence
that the deaths were caused by environmental stress or other
factors not related to endrin" (Velsicol, 1976). The
Agency rejects any conclusion that evidence of environmental
-36-
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stress is sufficient to exonerate the potential role of a
pesticide in the cause of death. In the laboratory, birds
killed by cyclodienes die with very low lipid reserves, so
that one cannot conclude that the absence of fat in a bird
found dead in the wild was caused by starvation or parasi-
temia independent of pesticide residues. Moreover, the
accumulation of lipid reserves by birds presumably is an
adaptation to counteract the effect of various environmental
stresses. If depletion of these reserves occurs as a
consequence of normal stresses, an increase in the amounts
of pesticides in the brain is to be expected (Barbehenn,
1976). IŁ these levels reach toxic concentrations, it begs
the question to argue that the bird would not have died from
pesticides had it not been for the stresses.
However, the Agency has revised its original
position on the role of endrin in the death of the brown
pelicans based on the pesticide residues in the white
pelicans which were found dead near Tulelake, California.
The concentrations of endrin in the brains of the 9 white
pelicans that probably died from pesticide poisoning in 1975
ranged from 1.3 ppm to 2.7 ppm (PD#1, App. MM). Three of
four pelicans which were analyzed after their deaths in 1976
(Stickel, 1976) showed concentrations of endrin ranging from
0.74 ppm to 1.2 ppm. The fact that this range of concentra-
tions of endrin (0.74 ppm to 2.7 ppm) exceeds that found in
-37-
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the brown pelicans (0.18 ppm to 0.70 ppm) forms the major
basis for the revised conclusion that the concentrations of
endrin found in the brown pelicans were not sufficient
to have killed the pelicans (Markley, 1977). The Agency
concludes that the risk to endangered species has been
rebutted for the brown pelican.
The Agency also received a very lengthy and
detailed rebuttal from Or. Gordon Edwards (1976). Dr.
Edwards' relevant points have been adequately addressed,
in the Agencys response to Velsicol's rebuttal on fatality
to the brown pelican.
After the RPAR notice, the PWRC analyzed a bald
eagle (PR 1164 from Wisconsin) that contained 0.61 ppm
endrin in the brain (Stickel, 1976). Following this lead,
the Agency requested that six additional eagles be analyzed
specifically for endrin. These individual eagles were
selected because they had symptoms of pesticide poisoning
but the original analysis which the PWRC had performed had
not revealed levels of pesticides adequate to have been the
cause of death. This analysis had not included endrin.
Of the six birds, one (PR 730 from Minnesota) was found to
have 2.1 ppm dieldrin in the carcass and 1.5 ppm in the
brain, plus 1.1 ppm endrin in the carcass (Reichel, 1977).
From a knowledge of the relationship between the concentra-
tions of endrin residue in the lipids of the carcass and
-38-
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those in the Brain, the concentrations of endrin in the
brain (which was not available for reanalysis) were estimated
to be 0.8 ppm (Barbehenn, 1977).
The PWRC now has the results of a large study
based on tests with several kinds of birds. The study
indicates that death is almost always indicated by a level
of 0.8 ppm or more endrin in the brain and that birds
usually survive at 0.6 ppm or less in the brain (Coppage,
1978). Thus, it appears that the two bald eagles discussed
above span the grey area of uncertainty regarding the
probable role of endrin as the primary cause of death. The
Agency concludes that a substantial risk to individual bald
eagles has been established. As indicated in the hearings in
Kansas City (EPA, 1977c), these two eagles most likely
acquired the residues of endrin from their wintering grounds,
where endrin is used on wheat.
In accordance with regulations implementing .
Section 7 of the Endangered Species Act of 1973 (43 FR 870,
January 4, 1978), the Agency requested formal consultation
with the U.S. Pish and Wildlife Service (FWS) in regard to
the potential impact of the use of endrin on Endangered or
Threatened species (Dreer, Oct. 17, 1977). On June 8, 1978,
the FWS submitted its biological opinion on the subject
-39-
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(Greenwalt 1978). The endangered species considered most
likely to be exposed to endrin included six birds, 11 fish
and 23 mussels. The Conclusion and Recommendation of the FWS
was: "Based on my consultation team's review of the above
information and other information and data available to the
Service, it is my biological opinion, subject to.the condi-
tions identified herein, that the use of pesticide products
containing endrin under present use restrictions is not
likely to jeopardize the continued existence of the listed
species considered herein or result in destruction or
adverse modification of their Critical Habitats. However,
since there is a potential that listed species could be
directly exposed to toxic amounts of endrin, I reiterate the
need for EPA to reinitiate Section 7 Consultation prior to
final actions including new label restrictions."
In compliance with this finding and request,
therefore, the Agency is submitting a copy of Position
Document 2/3 to the FWS so that it can determine whether
the proposed regulatory actions on endrin adequately address
the FWS's requirements.
5. The Presumption Based on Oncogenic Effects
a. Basis of the Presumption
The Agency's original conclusion that endrin
induces oncogenic effects in test animals was based on
reanalyses of two unpublished studies: a Food and Drug
Administration (FDA) study on the rat and a study on two
strains of mice by the Kettering Laboratory. Five other
-40-
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studies bearing on the issue were considered to be either
inconclusive as definitely positive or negative studies in
light of design deficiencies (Albert, 1976). Histological
results from the FDA rat study were reexamined by an EPA
consultant, Dr. Melvin Reuber. His tabulations of hyper-
plastic nodules, carcinomas and sarcomas in the livers
of both sexes as well as malignant tumors at all sites,
indicated a statistically significant increase over the
controls, especially at the lower doses. In the Kettering
mouse study, a statistically significant increase in hepa-
tomas was found for females only in one of the two strains
tested.
b. Velsicol's Rebuttal
Velsicol (1976) reiterated the conclusions
originally drawn by FDA in their study of the oncogenic
effects of endrin in rats. Those conclusions were (1) that
the data did not show a dose-response relationship, (2) that
the tumors found were not site-specific, (3) that the
animals did not exhibit the characteristic liver involvement
caused by chlorinated hydrocarbons, and (4) that the liver
weights of the test animals did not increase.
In addition, Velsicol attacked Dr. Reuber's
re-evaluation and diagnoses of the slides from that study
on three principal grounds: (1) that Reuber did not record
the diagnoses, slide by slide, thus preventing independent
confirmation of his diagnoses, (2) that there was a disparity
-41-
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between the numbers of tumors in the controls which he
reported and the number which the FDA reported in the
original study; and (3) that it was not clear whether he
reported the total number of tumors or the number of animals
with tumors. With respect to the Kettering mouse study,
Velsicol contended that the excess incidence of hepatomas in
the C3Q2F1-J mice was insignificant because the lesions in
the treated females occurred later than in the controls.
c. EPA's Response to Velsicol's Rebuttal
The Carcinogen Assessment Group (CAG) rejected
Velsicol's rebuttal (Albert, 1977) by indicating that the
criteria used by Velsicol in evaluating the FDA study, such
as dose-related increases in tumor induction and site
specificity, are not now considered to be essential elements
for assessing carcinogens, although they are common charac-
teristics of carcinogens. In the case of the Kettering
study, the CAG indicated that the response was dose related
and that the time-to-tumor relationship could not be fully
evaluated with the information at hand.
Dr. Reuber examined the FDA material in detail,
and his tabular presentation of the incidence of tumors by
treatment group was considered ample grounds for initiating
an assessment of endrin's oncogenic potential in humans
(Albert, 1976) However, because there were differences
between Dr. Reuber's interpretations of the lesions and
those which the FDA reported in the original study, CAG
-42-
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submitted the material to Dr. Frith of National Center for
Toxicological Research (NCTR) for another review of the
slides. For female rats, Dr. Frith reported 88% of the
total number of tumors (all sites, benign and malignant)
which Dr. Reuber had reported. However, the number reported
as malignant by Dr. Reuber was twice the number which Dr.
Frith reported. In the male controls, Dr. Frith reported two
with tumors; Dr. Reuber reported none. In males treated
with 1 ppm, 5 ppm or 25 ppm, the findings of the two scientists
agreed. For those treated with 0.1 or 10 ppm, Dr. Frith
reported one-third of the total number of tumors in 40 rats
which Dr. Reuber had reported in 36 rats, and only one-half
of the number of malignant tumors. Dr. Frith reported no
significant increase in the incidence of tumors in male or
female rats which were exposed to endrin.
In an effort to resolve the differences between
Dr. Reuber's and Dr. Frith's reports, CAG set up a review at
the FDA oŁ the liver slides for male and female rats treated
with 0.1 ppm and for males treated with 10 ppm. The review
was conducted by Dr. Frith and Dr. Dubin (CAG). It was
found in the slide review that there were 5 cancers involving
the liver, as reported by Dr. Reuber, but only 1 was a
primary cancer of the liver, the other 4 being metastatic.
Later, Dr. Dubin independently reviewed the liver sections
of the following groups in the FDA study: controls (both
sexes), 0.1 ppm (both sexes) and 10 ppm (males). Dr. Dubin's
findings substantiated both Dr. Frith's findings and
those findings originally reported in the FDA study.
-------
Dr. Reuber's original diagnosis of the FDA
slides provided the major basis for the Agency's issuance of
an RPAR based on oncogenic effects in laboratory animals.
Dr. Reuber did not submit a slide-by-slide diagnosis
and declined to participate in the group review of slides.
The group review did not confirm Dr. Reuber's findings.
Consequently, the weight of the evidence with respect to the
oncogenicity of endrin has shifted since the RPAR was
issued. The CAG having reviewed four bioassays on rats and
three on mice, has concluded that the weight of the evidence
therefore, is that endrin is "unlikely to be a human car-
cinogen" (Albert,. 1978).
6. The Presumption Based on Fetotoxic and
Teratogenic Effects
a. Basis of the Presumption
The Agency presumed against endrin on the basis
of a study by Ottolenghi et al. (1974) in which hamsters
were given a single dose of endrin (5 mg/kg), on either day
7, 8, or 9 of gestation and mice were given 2.5 mg/kg on a
comparable regimen. In the hamster, defects such as open
eye, web foot, and cleft palate tended to be associated with
each other. The first two defects were associated with
low fetal weight. Fused ribs, however, occurred independently
and were indicative of a teratogenic effect. In the mouse
there was a statistically significant increase in open eye
and total abnormalities. Since no other dosages had been
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used in the study and the Agency could not determine what
risks to humans might occur from exposure to endrin, the
Agency directed registrants to conduct studies to identify
the no-observed-effect level.
b. Velsicol's Rebuttal
Velsicol's rebuttal contended that the.Ottolenghi
study did not comply with EPA's criterion for teratological
studies—specifically/ that three dosages must be utilized
in order to establish a no-effect level. In the Ottolenghi
study, two species were each given one massive dose.
Velsicol illustrated the "exaggeration" of extrapolating
risk from a single massive dose by asking Mr. Reo Duggan to
compare the dose with the "average daily intake of endrin."
Mr. Duggan's calculations illustrate that the dose rates
used in the Ottolenghi study were from 12,500 to 25,000
times higher than the Food and Agriculture Organization/
World Health Organization Acceptable Daily Intake (ADI) and
from 250,000 to 500,000 times higher than the highest
average daily dietary intake found in FDA's Total Diet
Studies.
Additionally, Velsicol cited testimony by
Dr. Ernest Thorpe who characterized the study els "uncon-
ventional," pointing out that the vehicle, corn oil, alone
caused adverse effects on the hamster fetuses, thus casting
uncertainty on the contribution of the corn oil to the
experimental results with the pesticides.
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After consulting with the Agency, Velsicol
commissioned the International Research and Development
Corporation- (IRDC) to conduct teratological studies in the
rat and the hamster. The IRDC study (1978) tested the
effects of administering endrin by gavage daily during
organogenesis to hamsters (days 4-13) and rats (days 6-15).
Rats were sacrificied on day 20 and hamsters on day 14 of
gestation. Vitamin A was used as a positive control. The
endrin was administered as a suspension in 0.5% Methocel.
A preliminary range finding study in pregnant
hamsters was interpreted by the investigators as indicating
a 10% reduction in weight gain during gestation in the high
dose group (2.0 mg/kg/day) as compared to controls. In the
definitive study, doses of 0.1, 0.75, and 2.5 mg/kg/day
failed to induce any statistically significant effects on
the dams or the fetuses.
In the rat, a similar range finding study was
interpreted by the authors as indicating that behavioral
toxicity (increased irritability, salivation, and tremors)
occurred in the 1.0 and 2.0 mg/kg/day dose groups. Animals
in the 2.0 mg/kg/day group were reported to have a reduced
weight gain when compared to controls. With the exception
of one female in the high dose group, no maternal behavioral
effects were noted in the definitive study although a
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reduction in maternal body weight gain occurred at the high
dose level (2.0 mg/kg/day). With the exception of reduced
fetal weight at the high dose level, there were no fetal
effects attributable to endrin.
c. EPA's Reply to the Rebuttal
Since Velsicol used a test protocol that followed
EPA's proposed Guidelines for teratology testing in which
they gave daily doses to the animals throughout the critical
period of organogenesis rather than the single dose which
Ottolenghi used, the Agency conducted a study of teratogenesis
in hamsters using tests based on each of the Ottolenghi and
IRDC protocols (Chernoff, 1978}. The original rationale for
this approach was that the treatment of an animal before the
critical period could induce the production of enzymes or
other physiological changes that could alter the effect of
subsequent treatment (Barbehenn, 1977). The Agency's
studies produced results which are at variance with both
those of Ottolenghi et al and the IRDC studies and which
lead the Agency to conclude that endrin is teratogenic in
the hamster.
Chernoff administered endrin to pregnant hamsters
by gastric intubation. Initially he used dosages chosen to
duplicate those used in the Ottolenghi study or to bracket
the highest dose used in the IRDC study. However, he found,
in the first case, no evidence of retarded fetal growth and,
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in the second, a high incidence of maternal death. Therefore,
he repeated the studies using single oral doses of 0, 0.5,
1.5, 5.0, 7.5 or 10.0 mg/kg administered on day 8 of pregnancy
for the acute study and dosages of 0, 0.75, 1.5, 2.5 or 3.5
mg/kg/day administered on days 5 through 14 for the multiple
dose study.
In addition, he treated a second group of females
with single oral doses of 10, 13.3, 16.7 or 20.0 mgAg* and
determined the acute LD50* He treated a third group with
endrin (0, 0.75 or 1.5 mg/kg) during days 5 through 14, and
observed the effects of treatment on rearing behavior and
ambulation 4 hours after the last treatment. On day 38,
postpartum he retested the mothers and observed open
field behavior and exploratory activity in 20 and 70-day old
pups, respectively.
When Chemoff administered single doses of endrin
on day 8 of gestation, the numbers of maternal deaths,
the pregnancy rate, the maternal weights during pregnancy,
the ratios of liver and body weights, the numbers of fetal
deaths, fetal weights, and the maternal behavior were not
statistically different from the controls. In the absence
of any overt embryolethal or matemotoxic effects, a single
dose of endrin administered on day 8 produced meningoen-
cephaloceles at doses above 1.5 mg/kg and fused ribs at
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doses above 5.0 mg/kg. The effective dose for the produc-
tion of fused ribs was higher in the Chernoff study in
comparison to that of the Ottolenghi study. This is consis-
tent with a higher LDgg in the Chernoff study (18 rag/kg
was opposed to 10 mg/kg in the Ottolenghi study).
The administration of multiple doses of endrin
produced significant maternal lethality at doses of 1.5
mg/kg/day or greater. With increasing doses of endrin,
there was a dose-related increase in fetal mortality
(p<0.05) and decrease in fetal weight (p<0.001). Two of
twenty litters in the 1.5 mg/kg/day multiple dose groups had
a total of 4 fetuses with meningoencephaloceles suggesting
that this effect is producible in this regimen at a lower
dose than in the acute study. The relationship between
maternal lethality and the production of this defect is
unknown at this time. The reason for the difference in
teratogenic effects between single and multiple dosing has
not been established.
A low incidence of fused ribs was noted in the
low and high dose hamster groups of the IRDC study. Although
the results are not statistically significant, they are
suggestive of a dose related effect since they are consistent
with both the Ottolenghi and Chernoff studies. The IRDC
study has failed to evaluate the potential of endrin to
induce teratogenic effects in hamsters since it did not
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include a dose level high enough to elicit either maternal
or fetal toxicity, i.e. the dose-response curve is incomplete.
Finally, Velsicol's contention that corn oil is an inappropriate
vehicle, as demonstrated by Ottolenghi's results, is invalid.
In order to conclude that corn oil, per se, can produce
adverse fetal effects, it would be necessary to compare corn
oil treated hamsters, with sham treated hamsters. As Chernoff
indicated, Ottolenghi's control hamsters were not sham
treated, making that part of the study invalid.
Since the Agency now has the results of additional
studies, Velsicol's rebuttal regarding the impropriety of
extrapolating risk from a single, massive dose is irrelevant.
The no-observed-effect level in hamsters was established by
Chernoff to be 1.5 mg/kg for a single exposure during
organogenesis and teratogenic effects were observed in the
absence of maternal and fetotoxic effects. Whether or not
an adverse chronic effect (other than oncogenicity or
mutagenicity) observed in laboratory animals is a cause for
concern over human risks depends on the calculated margin of
safety.
The margin of safety (MOS) is the ratio of the
highest dosage from which no adverse effects are observed
in test animals and that level of exposure which can reasonably
be expected for humans. While the Agency has not established
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official guidelines for determining the adequacy of the MOS
for teratogens in general, Agency toxicologists believe that
an MOS below 100 would be a matter of serious concern.
Interpreting these values, however, requires a judgement
based on other factors associated with characteristics
of the chemical, routes of exposure, and the probability
of various levels of exposure. Thus, the above value
should not be construed as an established Agency policy but
only as a toxicological guideline for risk assessment against
which benefits must be balanced and additional safety
requirements imposed.
In the case of endrin, the Agency has additional
information that requires a substantial deviation from the
above MOS guideline. Specifically, limited epidemiological
evidence indicates that humans may experience convulsions
from exposure to endrin at a dose 50 times lower than that
at which this effect was observed in hamsters (Burnam,
1978d). For endrin, therefore, differences in sensitivity
between species are five times greater than the conventional
factor of 10 used in evaluating the MOS when comparative
information is not available. One can not necessarily
conclude from this that humans are 50 times more sensitive
than hamsters to teratogenic effects. However, since
the mechanism(s) of action of teratogens are generally
unknown, since sensitivities to teratogenic effects may vary
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by more than a factor of 10 between species and since the
teratogenic mechanism of action for endrin is unknown, the
comparative data on convulsions must be taken as a warning
to employ a more conservative interpretation to the MOS.
The Agency must conclude, therefore that an MOS of 500 or
less is a basis for serious concern. As indicated by the
exposure analyses associated with the various uses of endrin
(below), margins of safety of less than 500 can reasonably
be anticipated and the Agency concludes that the margin of
safety is inadequate to rebut the trigger.
B. Other Agency Concerns Relative to Risk from
Endrin
1. Effects of chronic exposure
Endrin is currently registered for use in the
U.S. on cotton, small grains, sugar cane, and in orchards
(ground cover for mouse control). These registrations are
designated as "extended no-residue registrations". Under
existing Agency policy, no-residue registrations were to
have been converted in registrations covered by tolerances
established under the Federal Food, Drug and Cosmetic Act.
No tolerances for endrin have ever been
established because it had not heretofore been possible to
establish a "no-effect level" or acceptable daily intake
(ADI). The Agency has recently determined a tentative ADI
for endrin (Engler, 1978).
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In long term animal feeding studies, a no
observable effect level was determined at 0.025 mg/kg/day.
At higher levels, liver, kidney and heart were affected
by Cndrin. Based on this result we can determine an
exposure level for humans which would represent an acceptable
risk. This acceptable daily intake would be 0.0002 rag/kg
body weight/day, or 0.012 mg/day for an average 60 kg
person.
The Agency's earlier review (EPA, 1973) calculated
that the average dietary intake for the period of 1964-1970
was 2.5 percent of the ADI, and endrin residues in the diet
appear to have declined since that base period (Ebner,
1978). Thus, the Agency has had no basis for concluding
that the observed adverse effects in rats and dogs from
chronic exposure to endrin, when considered in relation to
estimated human dietary exposure, were indicative of risk to
humans. However, the Agency has not concluded that the
available chronic tests satisfy the needs for establishing
an official ADI and additional testing may be required for
setting finite tolerances.
2. Mutagenicity
It its review of the oncogenic potential of
endrin, the CAG reviewed several papers dealing with the
possible mutagenic effects of endrin and concluded from this
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review that the results were "equivocally positive" (Albert,
1978). The Agency is unwilling to issue an RPAR on the basis of
such evidence but it will require that the issue be resolved
by compliance with the Pesticide Registration Guidelines
prior to both reregistration and to the setting of tolerances.
3. Metabolic Fate in Man
Unlike its stereoisomer, dieldrin, residues of
endrin have never been reported in samples of human adipose
tissue (Mississippi, Epidemiologic Studies Programs, 1978).
While there may be various reasons for this observation, one
possibility is that endrin is rapidly metabolized to hydro-
philic compounds and excreted. However, in a study with the
rat (Hutson, 1975), it was found that a highly toxic metabo-
lite, 12-ketoendrin, was produced and that this metabolite
was lipophylic. This lead the authors to observe that,
"This metabolite could be very significant for use in
monitoring suspected acute exposure to endrin".
On September 8, 1976, the Agency formally
requested Shell Chemical Company to provide information on,
"Results of any attempts to determine the presence of
12-ketoendrin in human and other organisms" (Dreer, 1976).
On December 14, 1976, Dr. E. L. Hobson submitted to the
Agency an undated report by Michael K. Baldwin entitled, "A
Brief Guide to the Metabolism of Endrin..." Relying on a
1973 paper by Baldwin and Milner, Baldwin concluded that
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"12-ketoendrin is thus unlikely to occur as a residue in
man's tissue." When the discrepancy between this conclusion
and that of Hutson, Baldwin and Hoadley cited above was
brought to Dr. Hobson's attention by a letter (Barbehenn,
Feb. 17, 1977), Dr. Hobson replied that Shell had no
data on 12-keto endrin in adipose tissues oŁ Pernis workers
(Hobson, July 1, 1977).
The Agency still does not know whether or not
12-ketoendrin may be expected to occur in the adipose
tissues of individuals which are exposed to endrin. This
critical question remains unresolved.
C. Risk Assessment of the Major Uses of Endrin
The RPAR criteria for risk reflect a concern with the
potential which the use of a pesticide .has for adverse
effects on man and on the environment. The anticipated
adverse effects from the use of a pesticide, however,
vary with the extent of exposure to the pesticide which
may be different for each of its uses. In order to assess
the risks from the use of endrin, the Agency concentrated
primarily on its three major uses: cotton, small grains,
and orchards. The Chemistry Branch, Hazard Evaluation
Division (BED), OPP) conducted the analyses which estimated
the amount of exposure to endrin from each of its uses. In
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conducting the analyses, the Chemistry Branch used informa-
tion both from labels and from field studies. Using toxicity
data and field evidence, the Metabolic Effects Branch and
the Ecological Effects Branch then utilized the exposure
data to determine the risks and their extent from the
amounts of endrin exposure to humans and the amount of
endrin contamination in the environment associated with each
major use of the pesticide.
1. Cotton
From the standpoint of risk to humans, the
Agency's concern is with the teratogenic potential of
endrin. The Agency agrees with the position adopted by
Velsicol and discussed in Section 6(b) that the average
amount of exposure to endrin which the general population
has from food, air and drinking water contaminated by endrin
provides an ample margin of safety (greater than 10,000).
However, the Agency is concerned about women who may consume
large quantities of fish containing endrin and those who may
on occasion be exposed to concentrations of endrin from
drift.
The use of endrin on cotton is normally at the
rate of 0.4 lbs a.i./acre, and the Agency's Benefit Analysis
indicates that cotton growers who used endrin applied it an
average of five times per season. Human habitations are
common on the periphery of many cotton fields, thus providing
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many opportunities for exposure to drift. Should a normally
clad bystander be caught 80-85 feet down wind from aerial
application, a reasonable estimate of dennal exposure would
be 1 mg (EPA, 1978b). If the bystander absorbs 10% of
the endrin per day, the dose would be 0.0017 mg/kg for a
60 kg person. The absorption value of 10% is based on
an analogy with studies of aldrin, dieldrin and lindane
(Burnam, 1978c).
For aerial applicators, inhalation exposure
was estimated at 0.011 mg/hr and dermal exposure at 0.16
mg/hr. If 10 % of the dermal exposure is absorbed, the
total daily dosage for a 60 kg female pilot actually apply-
ing endrin for ten hours a day would be approximately 0.005
mg/kg. The Agency estimated that approximately 100 pilots
were involved in aerial application of endrin to cotton
(EPA, 1978b). The number of female pilots among this
group is probably very small (Barbehenn, 1978h). Inhalation
exposure to mixers/loaders is estimated at 6.8 ug/hr.
Dermal exposure due to accidents would be very sporadic and
the level of exposure can not be estimated.
In the cotton areas of the lower Mississippi
River, rainfall is frequent during the growing season and
the proximity of streams and ponds to cotton fields makes
contamination by runoff common. FDA surveillance of residues
from commercial catfish ponds has disclosed endrin residues
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as high as 0.5 ppm. Considering the frequency of reported
fish kills, concentrations of endrin residues in excess of
1.0 ppm in living fish would not be rare. The consumption
of 250 g of fish containing 1.0 ppm endrin would produce a
dose of 0.25 mg or 0.004 mg/kg for a 60 kg woman.
In comparison with the no-observed-effect-level
of 1.5 mg/kg which Chernoff observed in the hamster for
encephloceles, exposure to applicators (0.005 mg/kg) pro-
vides a margin of safety of 300. For the local population,
the dermal exposure of 0.0017 mg/kg and the food exposure of
0.004 mg/kg provide margins of safety (MOS) of 880 and 375,
respectively (Burnam, 1978c). It is not possible to estimate
the probability of obtaining teratogenic exposure and
the frequency of such incidents can not be accurately
estimated. However, the'frequency is a function of the
number of treatments per acre, topographic and climatic
conditions, application techniques, the rate of application,
and the precautions which the applicator takes to avoid
contaminating people and water. The Agency concludes that
the use of endrin on cotton presents a teratogenic risk to
female applicators and women who consume large amounts of
fish contaminated with endrin.
The risk of endrin to local fish populations
from its use on cotton has been established in the Agency's
rebuttal analysis and this adverse effect has been known for
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many years by cotton growers (Sears 1978). Risks to terres-
trial wildlife associated with cotton fields are possible
(Markely 1977) but the reality of the risk is uncertain.
Risks to endangered species, in terms of jeopardizing their
continued existence, have not been demonstrated (Greenwalt
1978). The potential risks to the brown pelican have been
established and would seem,to be proportional to the total
number of acres of cotton treated with endrin in the regions
that drain into the Gulf of Mexico and perhaps into the
Atlantic coast from South Carolina to Florida as well. The
Agency has established above (Section II) a qualitative
record that the past use of endrin on cotton has adverse
effects on fish and wildlife.
2. Small Grains
The margins of safety for teratogenic risks from
the use of endrin on small grains are in the same range as
those for cotton, i.e. from 300 for applicators to near
1000 for bystanders. However, many circumstances combine to
reduce the probability of exposure occurring. Single appli-
cations at the rate of 0.25 pounds a.i./acre may be made in
the late winter or early spring. Outbreaks of the cutworms
are sporadic and any given acre may require treatment only
once every several years with the mean frequency of treatment
depending on the geographic location of the acre. In
general, the density of humans living in close proximity to
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wheat fields is lower than the density of humans living in
close proximity to cottonfields. The time of year (late
winter or early spring) and lower dose of endrin used on
wheat further reduce the potential for dermal exposure. It
is less likely that humans will be exposed to endrin from
eating contaminated fish from wheat-growing areas than from
the areas where cotton is grown. In the wheat areas, there
are fewer fish-bearing waters, runoff is less frequent,
applications are less frequent, and the general amount of
fish in the diet is lower. As is the case with cotton, the
Agency can not reliably estimate the probable frequency of
exposure from concentrations of endrin which have a potential
for causing teratogenic effects.
As indicated in the rebuttal analysis, the risks
to local populations of fish from the use of endrin on small
grains in general, are substantially less than those which
the Agency expects from the use of endrin on cotton.
Nevertheless, drift (and run off) poses some risk, especially
during outbreaks of pests that require emergency treatment.
The extent of this risk depends on the distance of the water
from the point where endrin is applied on wheat, as well as
on other factors. There is some risk to bald eagles
which may be poisoned by consuming moribund and dead fish
associated with the use of endrin on small grains. However,
in the opinion of the FWS (Greenwalt, 1978), the use of
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endrin has not jeopardized the continued existence of either
the bald eagle or of other endangered species. Risks
associated with the use of endrin to control other pests of
small grains will be discussed in Section V.
3. Orchards
Endrin is applied as a post-harvest ground
spray in orchards primarily to control pine voles (mice)
in the Eastern United States and meadow voles in the North-
west. Rates may vary from 0.6 to 2.4 lbs. a.i./acre. High
nozzle pressures (500 psi) are recommended on the label to
achieve penetration of the ground vegetation but practices
and equipment vary widely, resulting in the generation of
everything from a solid stream to a relatively fine spray
during application. Field estimates of exposure to normally
clad applicators were 0.01 mg/hr by inhalation and 3 mg/hr
dermal (EPA, 1978b). The number of women among the estimated
2200 orchard applicators is unknown, but, assuming four
hours of actual spraying per day, the margin of safety for
this amount of exposure would be about 75 in the absence of
protective clothing and this MOS indicates a high level of
teratogenic risk. The amount of exposure to bystanders
can not be estimated from the available data. The State of
New York conducted a monitoring program in endrin-treated
orchards in the Lower Hudson Valley in 1977. A report
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citing the concentration of endrin residues found in
specimens of dead and living fish and wildlife, and in a
dead cow, is not yet available. Pish kills resulting from
runoff of endrin from orchards have been verified from North
Carolina and Pennsylvania (Coppage, 1978).
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III. Benefit Analysis
A. Introduction
The Agency has prepared analyses of the economic
consequences which would occur if the Agency were to cancel
the use of endrinf or if endrin were to be used under
more stringent restrictions. In the preparation of these
analyses, the Agency's personnel used, among other sources,
an assessment prepared by the U.S. Department of Agriculture
(USDA) in cooperation with various state agencies, the
records of several hearings conducted under Section 21(b) of
the FIFRA, prior Agency reports and reviews of endrin, and
pesticide registration documents. This section summarizes
the major conclusions of the economic analysis, and provides
a background for the specific dollar figures and the other
qualitative effects.
The Agency performed an analysis of the impacts of
cancelling endrin in 1973 (EPA, 1973). This document, plus
the review of any new data and the review of early studies
formed the basis for USDA's report which was submitted to
the Agency on November 4, 1976. The individuals reponsible
for the .USDA assessment developed an estimate of the economic
consequences which would occur if the Agency were to cancel
certain uses of endrin. They used yield and efficacy data,
information on the ways farmers and others actually use
endrin, and other relevant published data.
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EPA's analysis centered on those sites where
endrin is used which earlier studies (including the USOA
report) indicated might be of economic importance, namely
cotton, sugarcane/ wheat and other small grains, conifer
seeds and apple orchards. The following sections present
a summary of the major findings for the use of endrin on
these sites. These uses were analyzed in depth in the
Preliminary Benefit Analysis of Endrin which was conducted
during 1975 to 1977 by the Economic Analysis Branch of the
Office of Pesticide Programs, EPA (EPA, 1977a). The following
discussion is based on information in this analysis unless
identified otherwise.
B. Cotton^/
Introduction
The discussion of benefit issues to follow relates
to the use of endrin in the effort to control Heliothis
spp., which are Heliothis zea (cotton.bollworm) and Heliothis
1/ The original Benefit Analysis for cotton was completed
in 1977 (EPA, 1977a). This analysis made the assumption that
if toxaphene were available it would be "... the most likely
alternative..." to replace endrin (EPA, 1977a, p. 98).
Several reasons, valid at the time, were provided to support
this assumption. More recently data on declining use of
toxaphene in Mississippi has been made available (Mississippi).
This data supports' informal reports from several sources that
use of toxaphene is declining. As a result, the original
assumption that toxaphene would be the major replacement was
reassessed. In addition, Velsicol has provided updated
usage of endrin on cotton (Velsicol). This Section provides
new information on the usage of endrin and its alternatives
and the modifications to the economic impact estimate.
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virescens•(tobacco budworm). The term "bollworm complex"
refers to both the cotton bollworm and the tobacco budworm.
Bollworms have the status of secondary pests on cotton.
Chemical treatment to control bollweevils (methyl parathion
is the pesticide most often used for bollweevils which
occur early in the season) frees the bollworms from attack
by predators and parasites and promotes the expansion of
their populations. When the damage from these increased
bollworm populations exceeds economic threshold levels, the
bollworms are raised to the status of primary pests on
cotton.
Various Integrated Pest Management (IFM) tech-
niques are available to ameliorate the damage caused by
bollworms. One example is the use of economic thresholds in
order to delay for as long as possible the first insecticide
application. This is important because the pesticides
currently used are non-selective in terms of the pests which
they kill. Once the first pesticide treatment is admin-
istered , the predator population is substantially reduced
but many problem pests remain. For many growers the only
tool of control, after beneficial insects are destroyed,
is the use of insecticides. Once the first spray has been
applied, many growers adopt a regular schedule, spraying
every third to seventh day throughout much of the growing
season. ~ (In rare cases the number of insecticide treatments
can exceed twenty or more in cotton growing areas). Other
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IPM technologies include early maturing and pest resistant
and determinant varieties of cotton and other practicies
such as scouting and numerous cultural practices.
IPM technology is in varying stages of development
throughout the Cotton Belt. IPM techniques are basically
preventive measures to control pests and thus to decrease
the use of chemical pesticides. Nevertheless, they cannot
totally prevent the outbreak of pests in all situations.
When outbreaks of pests occur at economically damaging
levels, chemical pesticides are the only curative measure
available. One thing is clear from usage data of insecticides
on cotton: at present, cotton growing areas identified in
the benefits study (Georgia, Florida, Alabama, Mississippi
and Arkansas) remain heavily dependent upon chemical pesti-
cides. These cotton growing areas coincide with areas where
there are heavy infestations of the bollworm and the budworm
and where endrin is and has been used.
The issue of how beneficial endrin is, is the extent
to which it is useful for the control of the Heliothis
pests. The discussion to follow will focus on the contri-
bution endrin makes to the control of Heliothis in the way
in which it is generally used; i.e. endrin is almost always
used in formulation with methyl parathion. The Benefit
Analysis reported the use of specific insecticides (i.e.
actual mixtures or formulations) and use of endrin by itself
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was not fbund in that particular survey (EPA, 1977, p. 65).
Endrin was used alone in the 1950's and early 1960's.
Due to the fact that cotton pests rapidly developed resistance
to endrin alone, most of the endrin which has been used
since the early 1960's to control the insects which damage
cotton has been used in a"formulation with methyl parathion.
Thus, the productivity provided by endrin is the added
insect control it provides when combined with methyl parathion.
Although endrin is currently registered for the control of
numerous other insects, many alternatives are available
which are economical to use and which also control these
insects. The states which recommend using endrin do so only
for the control of the Heliothis complex.
Osage
The amount of endrin which is used as an insecticide on
cotton has been small in relation to other cotton insecticides.
In 1972, it was reported that less than 400,000 pounds were
used on cotton (EPA, 1977a, p.67). During the succeeding
two years the use of endrin increased by a factor of almost
five. This temporary increase can be explained by several
factors including the shortage of organophosphate pesticides,
the cancellation of DDT in 1972, the significant increase in
the number of acres of cotton grown during 1973 and 1974,
and the relatively large infestations of the tobacco
budworm at that time. From 1975 to the present, the number
-67-
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of pounds of endrin which has been used on cotton has
declined significantly. Velsicol has recently estimated
that approximately 285,000 pounds of endrin has been used on
cotton during 1978 (Velsicol 1978). At the time the Benefit
Analysis was conducted (1976) the economic impact of the use
of endrin was based upon an estimate of 500,000 lbs. of
endrin which had been used that year. This amount translates
into less than 3% of the total number of acres planted in
cotton which are treated with insecticides. The amount of
endrin now used for the control of pests on cotton would
represent less than 2% of the total number of acres which
are treated with insecticides. The use of endrin has been
concentrated in Alabama, Arkansas, Florida, Georgia and
Mississippi.
Federal Registrations
Endrin is registered for numerous pests on cotton.
Table 1 lists the various pests.
Recommendations
Recommendations for the use of insecticides are formally
made each year by the states. The Benefit Study reported
that two states, Arkansas and Mississippi, were recommending
endrin. Those two states were recently contacted by Agency
personnel (Ludvik). Arkansas reports that endrin is not
recommended for 1978 and that use of endrin is down sharply.
-68-
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Mississippi continues to recommend endrin but reports that
use has dropped off significantly. The only other state
recommending endrin at the current time is Alabama. The
state recommendations are for the bollworm and budworm
only.
Table 1
Cotton Insects for Which Endrin is a Registered Control
Aphids—^ , , Cotton fleahoppers
Army cutworms—' Cotton leafperforator
Armyworm-^ Cotton leafworm
Boll weevil Cutworms
Bollworm Desert Spider Mite-'
Brown Cotton leafworm Fall Armyworm
Cabbage looper Fleahoppers
Celery leaftier ,, Garden webworm
Climbing Cutworms—' Tobacco budworm
Cotton aphid-/
1/ Pests identified on labels on products containing 2
or more active ingredients. The pests in question
may or may not be controlled with endrin alone.
Source: EPA listings from Microfiche (Input January 1975)
Page 41 of the report from the 1978 Annual Conference
on Cotton Insect Research and Control mentions endrin along
with 18 other insecticides as a possible control for insects
which prey on cotton (National Cotton Council of America,
1978). The mention of a pesticide in this report does not
consistute a recommendation; the purpose of the list is
simply to provide information on which insecticides have
controlled cotton pests in the past.
-69-
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Resistance
The Benefit Analysis reported that since 1956 the
cotton pests against which endrin was used exhibited
resistance to it at low levels over widespread areas in
Arkansas and Louisiana. Due to the development of resistance
in Louisiana it had become uneconomical by 1962 to use
endrin to control the Heliothis complex on cotton (EPA,
1977). Table 2 shows the amount of increase in the tobacco
budworm's resistance to endrin between 1961 and 1965 in the
state of Texas (2.3-491.7). The amount of this increse in
resistance is greater than that for all other comparisons,
and this helps to explain why endrin is no longer used in
Texas. The Agency recently contacted the states of Arkansas
and Mississippi to find out how much endrin was being used
for the control of cotton pests. These states reported a
decline in the use of endrin on cotton and explained that
this delcine was due to the resistance of the cotton pests
to endrin.
Alternative Insecticides
Only a limited number of the federally registered
alternatives have been shown to provide control of the
resistant Heliothis populations (USDA, 1977). Endrin is
believed to be used in those areas where the bollworms
exhibit resistance to the use of methyl parathion by
itself. The RPAR alternatives include toxaphene-methyl
-70-
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Table 2.—Relative toxicity of insecticides applied topically to the tobacco budwonn.
insecticide
and
location
^50 1
(m/g larva)
1961
1964
1965
1967
1969
1970
1972
Texas
DDT
4.9
627.4
Endrin
2.3
491.7
Carbaryl
11.4
2069.9
Strobane-DDT
27.7
422.6
Toxaphene-DET
17.9
133.8
Methyl parathion
College Station
0.4
1.1
0.8
2.3
5.3
Weslaco
4.2
17.5
Menocroptcphos
College Station
4.9
3.8
5.3
14.4
9.1
Weslaco
7.6
5.3
Louisiana
Methyl parathion
Natchitoches
Curtis
4.2
3.4
Ississippi
Methyl parathion
Jefferson-Davis Co.
Monroe Co.
Lawrence
Quitman
Sharkey
Bolivar
0.6
0.2
5.7
35.8
4.4
4.0
Source: DSDA. The Bollwonn and the Budwonn on Cotton. Status of
Insecticides and other Methods of Control of 1977.
USDA, Washington, January, 1977.
-71-
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parathion and EPN-methyl parathion (EPN is on the Pre-RPAR
List). Several non-RPAR chemicals are available and include
monocrotophos, methomyl, acephate and several others.
Although methyl parathion is registered for use on the
bollworms it is not effective for controlling resistant
populations. Most of the methyl parathion used is for
bollweevil control (O'Mara,1978a). Several new pesticides
are not currently registered but they have been available
under Section 18 of FIFRA to farmers who have experienced
difficulty in controlling the bollworm and budworm. These
new insecticides include sulprofos, profenofos, permethrin
and fenvalerate. Collectively these insecticides are being
used on an area which is substantially greater than the
number of acres of cotton on which endrin was used in the
1970's (O'Mara, 1978b). These new insecticides are providing
good control of the budworm and bollworm complex in many
areas because resistance to them has not developed (USDA,
1977b).
Economic Impact Analysis
To address the benefit endrin provides for Heliothis
control-on cotton it is necessary to project the pest
control practices farmers would most likely use to replace
endrin if it were not available. The benefit which endrin
provides is measured by changes in both costs of production
and income associated with the change to alternative pest
control practices. The changes in costs can be due to
-72-
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different application rates, prices per pound of active
ingredient, application costs and number of treatments.
Changes in income can be due to different yields and varying
grades of cotton quality. It is first necessary to identify
those practices and second to allocate them over the amount
of acreage currently treated with endrin.
The choice of insecticides to replace endrin and the
proportion of total acreage to be treated by each could be
determined by a survey of farmers currently using endrin.
Available resources do not permit the costly and time
consuming exercise to identify the subject farmers and to
survey their expected alternative pest control practices.
The four most viable alternatives among those registered
federally for bollworm control are toxaphene, .EPN, monocro-
tophos and methomyl. In addition, several new insecticides
were made available in 1977 and 1978 under Section 18 of
FIFRA. These insecticides include sulprofos, profenofos,
fenvalerate and permethrin. Since these chemicals are
currently being used much more extensively than endrin, it
is appropriate to consider them in assessing the impact of
the loss of endrin.
There are several factors which farmers consider
in making choices. Farmers are motivated by the possibility
of decreasing their production costs and by increasing
their income. Farmers make choices among pesticides based
-73-
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upon their costs and upon their ability to control insects.
Table 3 lists the alternatives, the application rates and
material costs per acre for the insecticides which are
identified as alternatives to endrin. Toxaphene and EPN are
the least expensive of the alternatives. If they were to
consider costs alone, fanners would have an incentive to
choose these. However, other factors such as the effect of
the pesticide on the yield from the crop are important in
the selection of an insecticide. (The performance of the
insecticides which are alternatives to endrin is discussed
in a separate Section).
A major factor in assigning the acreage distribution of
alternatives should be current practices of farmers. A
recent study on usage of pesticides in Mississippi provides a
good data base for distributing the most popular bollworm
insecticides over the endrin acreage (Mississippi State
University, 1977). This data helps to indicate what
practices are being followed at the current time and to show
trends in practices from recent years.
Other sources of information are available including
previous studies and knowledge of experts in EPA, USDA, the
States and elsewhere. These sources of information are
helpful to assign a level of confidence in the data used as
a basis for impact analysis.
-74-
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'"able 3. Application rate and material cost per acre for
single application of endrin and alternative,
insecticides for budworm-bollwonn control
Insecticides
Application Material cost
rate per acrel/ per application/
Present insecticides
tcocaphene + methyl parathicn
EFN + methyl parathicn
mcnocrotophos
methanol
endrin - MP
3/
New insecticides^'
permethrin
fenvalerate
olprofos
lbs. a.i.
dollars
2.0 + 1.0
0.5 + 0.5
1.0
0.45
0.4
0.1
0.1
1.0
2.75^/
2.80^
4.60^
4.ooŁ
2.18
6.40*/
6.00^
6.0&
1/ Taken frcm 1976 Biological Survey for Ttaxaphene Assessment. QSPjT
2/ In addition, the application cost per acre is estimated
at: Southeast - $1.25; Delta - $1.60; Southern Plains -
$2.50; and Southwest - $1.75.
3/ All hit sulprofos are synthetic pyrethroids.
4/ Average of data provided by Hercules ($2.60), Fred Cooke
($2.70). Art Grube ($3.00), and Gold Kist Corporaticn
($2.75).
5/ Southern States Cooperative
6/ Based an discussion with pesticide manufacturers, October 1977.
-75-
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The method used to allocate the identified federally
registered alternatives over the endrin acreage was to use
data on pesticides from 1971 to 1976 from Mississippi
(Mississippi State University, 1977). The justification for
using this data base is:
1. It is a consistent time series data base for the
viable bollworm insecticides/ and
2. Mississippi is. well suited to address the endrin
issue because,
a. the total usage of endrin recently provided by
Velsicol indicated that 335,984 pounds of
endrin were sold for cotton in 1976 (Ebner,
1978c and e). The Mississippi data indicate
that 329,288 pounds of endrin were used in
1976. If these figures are reasonally representa-
tive then most of the endrin used on cotton, at
least for this year, was in Mississippi.
b. Mississippi has climatic conditions and pest
complex problems similar to other cotton states
using endrin.
The Mississippi data show a significant decline in
poundage of toxaphene in Mississippi and the subsequent
increase in EPN (Mississippi State University, 1977). Since
EPN is applied at 1/2 pound per acre, the relative increase
in acreage treated with EPN is even more dramatic.
-76-
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The distribution of the selected viable alternatives to
endrin over the endrin treated acreage was determined by
using the poundage figures from the Mississippi data for the
selected alternatives and the derivation of the total number
of treated acres by dividing the number of pounds of endrin
used by the application rates in order to get the total
number of acres treated. The total number of acres derived
for the selected endrin alternatives was used as the basis
for determining percent distribution. Table 4 presents this
information. Additionally, the data on the usage of new
insecticides from Mississippi is also included, although
this comprised only 3 percent of the total treated acres.
For purposes of this study the acreage distribution as
listed in the far right column of Table 4 is used for the
current assessment of the economic impact which would occur
if endrin were to be cancelled.
Estimate of Economic Impact of Cancelling Endrin
As mentioned above there are three factors which could
alter the net returns to growers who use endrin if it were
cancelled. These factors are changes in costs, changes in
yield and changes in quality of crop. As with any economic
analysis it is imperative that assumptions be made. The
assumptions to be made for the endrin analysis are discussed
below.
-------
.Table 4. Usage of Selected Insecticides to Substitute for
Endrin frcm Mississippi in 1 976=-'
Insecticide/
Class
Ttotal Pounds Application Total Treated Proportion of
Applied (lbs.) Rate (#/ac.) Acres (ac.) Total Acres (%)
KPAR
Itoxaphene
.EEN
4,421,638
2,469,759
2.0
0.5
2,210,819
4,939,518
25
56
Ncn-RPAR
Monocrotophos
Methanyl
971,805
227,381
1.0
0.45
971,805
505,291
11
6
Special Use
Exemption^
230,073
3
1. Source: Mississippi State University. Mississippi Epidemiologic Studies Program:
Annual Report #9. Mississippi State Univ. under Contract to HEMB, TSD, QPP, CPA
#68-01-1944.
. 3he insecticides available under Section 18 of FIFRA and which were used in
Mississippi in 1977 are sulprofos, pennethrin, and fenvalerate'. The treated
acreage was reported from: Mississippi Department of Agriculture and Commerce
car Bnergency Exemption Report - 1977, Mississippi State, Mississippi.
-78-
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To conduct the comparative cost analysis for addressing
an endrin cancellation, the alternative pesticides and their
proportional use over the endrin acreage must be specified.
Table 5 lists the insecticides and the acreage. The top row
of Table 5 lists the case for endrin. In the rows below,, the
case is presented for an endrin cancellation. The impact
assessment is based upon 1978 use of endrin as supplied by
Velsicol, which is 285,000 pounds (Ebner, 1978c and e). This
would allow 712,500 total treatment acres (this includes
multiple treatments). The original 1974 Benefit Analysis
derived the average number of treatment per year with endrin
which is 4.7 sprays per season, and this will be used
herein. The assumption is made that the alternatives would
be used an equal number of times. There is no way to verify
this assumption without extensive and costly investigation.
An enormous variability exists in treatment patterns across
regions and seasons due to numerous factors such as pest
density and composition, weather throughout the season and
so on.
This assumption could overstate the cost of replacing
endrin simply because more effective control obtained by the
alternatives could reduce frequency of treatment. However,
the estimate of costs based on this assumption would not
differ significantly if another assumption were made, i.e.
that some alternative pesticides were used fewer times per
season than others. Therefore, it is not necessary to
-79-
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TaJ" 5. Comparative Cost Analysis
Insecticide
Bases Acres
Treated ac.
Total Treat-
ment Acres
No. of Treatments
per Season
Material Cost^ Total Cost
Total Change All Acres
Endrin PHP ^
Alternatives
RPAR
'Itoxaphene - M.P.
EPN - M.P.
Non-RPAR
Monocrotophos
Methcmyl
New
Insecticide^/
151,596
37,899
84,894
16,676
9,096
4,548
712,500
78,125
399,000
78,375
42,750
21,375
4.7
4.7
4.7
4.7
4.7
4.7
Net Change in Cost
if Endrin is Cancelled
2.18
2.75
2.80
4.60
4.00
6.20
.57
.62
2.42
1.82
4.00
$1,553,250
489,844
1,117,200
360,525
171,000
132,525
717,844
1/ Ihe total oost Is the total chemical cost per acre. The change is the difference in cost
compared with endrin.
2/ this implied poundage figure for endrin was obtained from Velsicol and represents 1978 usage
or 285,000 pounds of endrin.
3/ Itie new insecticides include sulprofos, permethrin, fenvalerate and profenofos which represented
use in Mississippi during 1977.
-80-
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generate actual information from field experience because
that information would be of little importance for the
outcome of the analysis. Thus, this assumption will be used
in the budget analysis. However, the reader should be aware
that this assumption represents the worst case for this
particular variable.
The cost of shifting to the alternatives is a function
of the chemical cost per acre of the alternatives only since
the number of treatments is assumed to be the same and since
application costs are identical for all the pesticides
listed in Table 5.
In the far right column of Table 5, the total chemical
cost for each insecticide is listed. The change in cost due
to replacing endrin is therefore the difference between the
total endrin cost and the sum of the total cost of the
alternatives. If the Agency were to cancel the use of
endrin on cotton the total cost of using the alternatives to
endrin per year would be $717,850 (based on the amount of
endrin used in 1978).
The breakdown of this total amount is as follows:
- Average increase per acre in cost per treatment =»
$1.00
- Acreage increase per acre per year for all treatment =
$4.70, or less than 3% of total per acre production
costs
- Average increase per year per farm - $815 or less than
2% of the total revenue received from the cotton which
would be sold.
-81-
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The second factor to consider is the potential change
in yield per acre which might occur if endrin were unavailable.
The 1976 Benefit Study investigated the effects on yield and
decided -that there was no basis for assuming that the
effects on yield would be greater or lesser than those which
the use of alternatives pesticides might produce. Thus,
the assumption was made that the effects on yield would be
the same. The Agency investigated what the effects of the
use of alternative pesticides to endrin would be on yield
and found that no experimental trials have been conducted
since the original Benefit Study was completed (O'Mara,
1978a).
Yield effects of endrin can be inferred from certain
other available information. Endrin appears to have experi-
enced a significant downward trend in use during the 1970's.
This has happened in spite of the fact that endrin is the
least costly of all pesticide materials commonly used for
bollworm control. A decline in relative efficacy could be a
significant factor for explaining this trend. Alternative
insecticides are apparently providing relatively greater
economic control than endrin on that acreage being replaced
by its alternatives.
However, on the existing endrin treated acreage, there
are no recent yield data from experimental testing to serve
as a basis for choosing a non-zero estimate to represent
relative yield effects of endrin. For those growers using
endrin it is reasonable to assume they are achieving econo-
-82-
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mic control Łor they are most closely associated with endrin
use and its results. Since endrin is used on a small scale
(in terms of pounds, acres and users) the assumption for
relative yield is not critical for estimating economic
impacts. Therefore, in this study it was assumed that yield
effects were zero.
The final factor is the effect of endrin on quality
of cotton. However, there is no evidence of quality effects
associated with alternative insecticides on cotton.
In summary, the economic impact of the cancellation of
the use of endrin on cotton would be limited to increases
only in the cost of production. Endrin is the least costly
of the pesticides commonly used for the control of boll-
worms. Die increases in costs which would be due to the
use of more costly pesticides would have a relatively minor
effect on the growers. Nevertheless, the growers' average
gross income would be reduced by approximately $800.00 per
year. In the cotton market the economic impact of the
cancellation of the use of endrin on cotton would affect
only the user of endrin. There would be no change in
the national supply of cotton or in its price. Hence,
if the Agency were to cancel the registration for the use of
endrin on cotton, no effect from this action would be felt
by the members of the marketing chain or by the consumers of
products which are made of cotton.
-83-
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In addition to the fact that there are small benefits
for cotton fanners who use endrin its use also poses some
disadvantages. These are disadvantages for the cotton farmer
himself. These disadvantages arise from the accumulation of
endrin residues in the soil which translocate to oil
crops such as peanuts and soybeans. These crops are com-
monly grown in rotation with cotton. The use of endrin is
thus a constraint for the farmers who wish to use certain
crop rotation schemes. Since oil crops are often exported,
there is a definite possibility of a loss in export sales
from countries which will not accept oil crops containing
residues of endrin. There are other disadvantages from the
use of endrin on cotton which have not been quantified. For
example, there is a loss in recreational value which occurs
when the run-off of endrin from cotton fields kills game
fish and there is a loss in income for commercial catfish
operators when the run-off of endrin kills catfish.
These disadvantages are real and they offset to some extend
the small benefits endrin provides as an insecticide on
cotton.
C. Wheat and Other Small Grains
Annual endrin use varies between 222,000 to
277,000 pounds active ingredient for small grains.. Applica-
tion is made at 0.25 pounds active ingredient per acre
(Table 6 and Table 7). Current USDA estimates are that
-84-
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suwmt; or m.uniNARY benefit analysis - uaik/akky cnvoiss
A. USE:
S. MAJOR PESTS CONTROLLED:
C. ALTERNATIVES:
MaJo^^cg^jtt^fc^chonlc^
Scat* /Fcoeral r»ci>taNfod.icioni:
Hon-ehrmlol control*:
Efflcacv of alternative;
CcroelT« performance
C22ŁŁIŁŁŁ2LJiŁŁŁŁ: *
Condualoa>
d. uiun or nsz:
Active Ingredient basis:
(pouoaa a.1.)
(a) Eadrla
Cb) Alternatives
ttaltjM2**Ł*d_5Ł«Ł*:
(a) ladrln
(b) Alternative*
(e) Hoc treated
E. ECONOMIC IMPACTS!
U«tr:
Market:
Csniinir:
Harcoecomjulc:
r. sociAuemwwm ikpacis:
Svoll grains/cndrIn
Array cutvnrma
Endosulfan, Toxarlion* (KPAK)
7 state* reeonocnd controls (or arm' cutworm* on uncat.
A recosmcnd enorln, 1 enaosulfan, b coxaphenc, ana
6 trlchlorfon.
Hon*
Available data diowt endosulfan (0.2 lbi a.1./acre) deliver*
eeapazable control of on? cacworm*.
Ho yield or quality difference anticipated.
Tba endoeulian control proem cost* il.M co SI.94
¦or* par treated a era.
HE anticipate* no supply problea la ebe future. Prrxtarrlnn cas be
lacraasad should deaaad shift.
Stiti
lb*
He(li«lbla
Co
U-H
u
to - so
Ht
1
Ok
45 - 57
sn
7-9
Total
US - 173
Stat*
Aero*
(1.000)
Co
la
Ht
Ok
2E_
local
Betlltfble
221.0
200.0
3.7
226.7
36.0
«1>
teeming equivalent control, aggregate Ispecta ef adoption of esioeulfan
(0.5 lb* a.l./per acre) a* on alternative will total Sl.l nllllis to SI.3
Billion due to laereeeed ("h*n1r*l eexts. Th* average —f*n lspacr
la the five affected scacas 1* 10-11 dollars.
Projected Annual Increased Coet* ef Control ea «s Average Site
Wheat Tara* on Uhlcb All Acre* Have Continual Level* of
tcoiMWric Infestation*
Stat*
Per Acre La**
Per Fan loaa
(dollar*)
(dollars)
Co
1.66 - 1.94
524 - 612
b
1.66 - 1.94
324 - 379
Ht
1.66 - 1.94
668-780
0k
1.66 • 1.94
366 - 428
SO
1.66 - 1.94
300-350
Tb* resultant lacreaaed coat* of production ara
negligible on a national ecale.
Negligible
Negligible
eepected co be
C. LIMITATIONS 0T AIULTSIS:
a. PMKCIPAl ASA13ST AND DATE:
-35-
Analyelo uum emurable level of any cucwora control uslnt the
alternative at the apaelfled application rate*; cobcrol data, fcjwever,
la availaele la anir three of th* five affected acate*. Dlacrlaiclan
of vjb* of endrlo by fan and frequency ore unavailable.
Doena Ł. Tegelaen. ScsaaaAac
January, 1977
-------
Table 7
SWMAM or rfXLIKIKARY BCXTXT AKALY515 - GRAXHS/PAL& VCSTBK (XTVORKS
VSE:
MAJPt PrSTT rOSTROLLEa:
ALTrT-XATTVES:
>^lŁir'i^*r5JŁ
-------
416,000 acres and 691,000 acres are treated for pale western
cutworm and army cutworm each year, respectively.
According to the Benefit Studies, there are no
registered alternatives to endrin for pale western cutworm
control. Yield losses valued at about $33/acre could occur
on endrin treated acres (1976 Prices). Aggregate losses of
4.7 million bushels (0.28% of total U.S. production) with a
value of $14.9 million could occur annually without effective
control of the pale western cutworm. Colorado, Kansas, and
Nebraska would be the states most heavily affected.
Endosulfan is the primary non-RPAR registered
alternative to endrin for controlling army cutworms.
As indicated in Table 6, available data shows endosulfan
delivers comparable control of army cutworms. Since no yield
differences were anticipated, yields were assumed to be the
same for endrin and endosulfan in the benefit analysis.
Additional chemical costs would be $1.66 - 1.94/acre.
Total impacts would be 1.2 million dollars on the affected
acreage. Colorado, Kansas, and Oklahoma would absorb 90% of
the total impacts.
Market and consumer impacts are expected to be
negligible if endrin is cancelled for use on wheat.
-87-
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D. Orchards
Endrin is applied as a postharvest ground spray to
control pine and meadow voles in many apple-producing areas
oŁ the East and Northwest (Table 8). Current endrin usage
on domestic apple orchards is estimated at 84,000 pounds
active ingredient per year applied to about 58,100 acres
(11.2% of total U.S. apple acreage). In the nine states in
which endrin is used for orchard vole control OGeorgia,
South Carolina, North Carolina, Virginia, West Virginia,
Maryland, Pennsylvania, Washington, Idaho), the acreage
treated with endrin represents 26.5% of total apple orchard
acreage in those states.
The State and USDA Assessment Team considered pine
and meadow voles to be the most important threat to growing
apple trees and maintaining economic levels of production in
both the Eastern and Western apple-producing areas of the
U.S. During periods of environmental stress (generally
during summer drought and/or the winter months) voles feed
on the tree trunk and roots at or below the soil surface.
The voles gnaw phloem tissue from the trunk and roots.
Depending upon the severity of the damage, apple yield and
quality are reduced and tree growth is stunted. If 25% or
more of the trunk circumference is "girdled" the tree may
!
die within three years unless restored by grafting, an
uncertain and expensive process. Trees less than three
-88-
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t'SE:
Endrln uec aa posiharvcat iprav on app Le crcturas.
lOJ-LS W
•AJCHt PtSTS carrscus:
ALTSWATIVKi:
Sts-»/r»deral rtfwgaendntlons;
2joŁ2^Ł«clŁ»l_rontrol«:
EJ^gaev^ofjlteguKives:
CogBarac^v^oeŁfgraance;
Comparative costs i
Conclusion:
Pine voioa, auaw voles.
HPAK: nan*
Kan-RTAŁ: Federal registrations: sine phosphliw
State regiatratlncs: chloropnacinono (CPN), dlptuelnont OH!)
Habti of apple states (out of 20) recaoncndini;: endrin-6; tine phosphlde-13; CTS-2; Dre-3; strychnlne-l;
herblcldes-6; trunk guaros*!; nowing/euliivaiion-U.
Cultural practices (aovlag, cultivation, crunk guaras) and nonTodantlcido choreicsIs (herbicides) are uuil
to destroy tha food so urea* and nabisat o( vales and to directly proeact the tieti.
Is azaaa where endrln la still used (probably due to lack of davelopaant of realstant vela populations)
It Is the Best effective aaterlal available.
According to mu contsets, m of rise phosphide on acruti now treated vltta andrln will lead to a 6.6S*
weighted average lose la production par year as cha affected acreage. An analysis was alas cosplcted under
the assimpclno that the use of OS, OTS, herbicides aad cultural praetlca* would result la 5QX of cha loss**
IS production expected under a xlac phosphide progrsa (1.331 annual weighted loss).
!L
traaeasut cost/acre
Uumal spray
esdrla 1.6 EC
Crt 0.4 esse. „
err o.ooji pellets
OPR 0.0051 pellets
tOmtj earnest bait
cultivation * herbicide (paraquat)
cultivation
barbieIds (paraquat)
herbicides (sloaaloe ~ paraquat)
U6.40
r.4o
17.45
16.95
14.53
33 .«4
26.54
15.65
24.*0
Seasons I control prograas generally Include run
or sore of tha aathoda listad. Trapping aad trunk
guards ara alas uaad. Currant ondrin usars face a
ma firm aaaaonal control cost Increese of tii par
a ere (an 8.61 inert* sa in par acra aonharvett pro-
duction costs). Tba average Zdjfj and everege CPS"
DPB-herbleldas-eultural aethods prograas would
lneraaaa par aero aaaaonal control costs (relative
to tha average coat of eadrin control prograaa) by
J18 (1.672 of sounarrest production coats) aad $21
(1.931 of nonharveet production costs), respectively.
of ssdrto for orchard vole control vlll Increase production costs and reduce apple production on tha
acreage currently treated with andrln. Available alternatives do not provide adequate control la eras*
•abject to consistently high levels of infestation and daaaga.
UilVl OF SSS:
Active inrredlent egellei
anjjgjres^rjeajed:
B0SMXC VtUXS:
Peer;
Market:
wrti/meuiut ¦aotess:
I22STUZIOSS or AK4LX5X5:
ZHAL AKAX.75T AO MB;
State
fanrgls
South Carolina
torch Carolina
Tlrglnla
Beat Virginia
Barylaad
Pennsylvania
Total
^oet^jottd/vjir
300
900
3.000
4,000
9,500
900
10,400
30.200
700
U.100
Pound^aj^jjjjilied/veaj^
1,200
2.200
12,000
9,600
13.ICS
2,200
25,000
16,100
400
84,000
Asalyal* Hirtrort to InlrlsT Ttiraa roars following an endrin caneallarlim.
mmwi «Btrla U'ata trrcgrass:
0s«r
Eatioato^Chanjj^lnNct^^Rot^gs
Aaraalsg omtt aadris users adopt W!-0?S-harbleldee-
cultural aatbods prograaa:
Soar
jjarjgre
•(246
+S113
•aa
+» 37
•U9.UO.OOO
4951.323,000
•S 9,479,000
4423,773,000
tssmrlng uuiaui andris uaars adopt ptograas:
?xa*h applas
Procams spplas
AismIiu csrnat aadrin uoara adapt UFIt-uriMtarbicldaa-
oalanl aathoda prograaa i
Trash apples
Incssa applas
EatiŁjtŁii^tMnje^a-J^lut_ofUjSJ_ProduejiOŁ
farg_iava^
*t 4,965,000
402,668.900
*i 1,575,000
46 6,553,000
ISŁŁcaailZS^
-57.ai3.0O0
•n.962,000
Hot investigated la dapch. tkmeiar. loos la grower Inmaa abd reduced oaskaclags la affacted areas
' libel? to have an advacaa tffeiit en ai'.iiiaiii.i la localised areas.
1. apple production aasuaod to reaala constant in ism uuili'ln use areas.
2. To nrlnlwln aff acta of divers* orchard situations and eanageaenr pracdeea, s coapoelte acra
approach uns used.
3. No quantitative!r-basec eetlsstea of loaa undir tha alternative progress were available. Tha
crop lees estisate undar tha ZnjP^ pragma provided state paraonnal. looses under the CPB-0PN-
herblcides^alcural actaoda prograaa reoreeent an aasuoptlon by the aaalyat based on United
field test decs.
4. icng-tero wawar and industry euuuale iapacts could not be developed duo to a lack of suppl?-
prlca response data. Analysis liaised to three years tallowing cancellation.
5. So daca available u quantify eŁfesta of odrln vithdrswal upon fruit grades la affected aad
unaffected areas.
Mark A. Uictner, tcoaonat
Eeonaaic Aaolysla Craaeh
Criteria aad Evaluation Divtaion
Office of Pesticide Piugteas
7.S. EarlrnOTBtsl Procectlon Agoasy —89—
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years old cannot be saved by any method if girdling exceeds
33%.
Very few alternative rodenticides would be available
for use by apple growers in affected areas if the use of
endrin were to be cancelled. Zinc phosphide is the sole EPA
registered rodenticide of sufficient efficacy to be of any
use against orchard voles. Several states have obtained
registrations for two anticoagulant rodenticides—chloropha-
cinone (CPN) and diphacinone (DPN)(EPA, 1977a). Herbicides
and certain cultural practices (trunk guards, cultivation,
mowing) can also be used to reduce the risk of vole damage
by destroying or disrupting the voles' habitat and/or
primary food sources (grasses and forbs).
State extension and research personnel have estimated
that the loss of endrin and subsequent adoption of zinc
phosphide bait (the sole federal registered material of
sufficient effectiveness to be considered an alternative)
would result in a 6.66% annual loss in apple production on
the acreage currently treated with endrin. This represents
a 1.0% reduction in total national apple production.
If the cancellation of the use of a pesticide results
in losses in total national output of a product of sufficient
magnitude to cause a measureable change in the price of the
final product then several distinct groups in addition to
the group which uses the pesticide are affected. The groups
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which are affected are the producers of the product, including
both the users and the non-users of the pesticide, the
groups which market the product, and the consumers of the
final product. At the production level, a redistribution of
income occurs whereby the nonusers of the pesticide gain
and the users of the pesticide lose money. Whenever
the volume of production decreases, consumers normally
lose, because they pay higher unit prices for a smaller
total annual crop. In the case of apples, some peculiar and
paradoxical impacts occur which are not immediately obvious
to the casual observer. One effect of the cancellation of
the use of a pesticide on apples would be that the total
expenditures which are made for apples at the consumer or
retail level are smaller. Even though this would occur,
there would be a substantial gain in the total expenditures
for apples at the production level. This gain in revenue at
the production level is explained by an additional redistri-
bution of income which occurs between the marketing and
production levels whereby the producers of the apples gain
at the expense of the marketing firms. Although this may
seem unusual, this phenomenon occurs when the elasticity of
demand is elastic for the product at the retail level while
at the same time the elasticity of demand is inelastic at
the production level. This is the case for apple markets.
Current endrin users adopting the Zn2P3 programs
would experience a reduction in per acre net income of $69
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per year during the first three years after cancellation.
Total reductions in user net income are estimated at $5,336,000
per year for the initial three year period.
An analysis was also conducted based on the assumption
that endrin users would adopt control programs combining
CPN, DPN, herbicides, and expanded use of cultural control
techniques. This assumption indicated losses equivalent to
50% of those projected to occur under the Zn^P^ programs
(a 3.33% annual weighted average loss in production) on the
affected acreage. Endrin users adopting the CPN-DPN-herbici-
des-cultural methods programs would experience (based on the
efficacy assumption) reductions in per acre net income of
$34 per year during the initial three years following
cancellation. Total reductions in user net income under
this program are estimated at $2,645,000 per year for the
three year period.
E. Sugarcane
The use of endrin use on sugarcane, once widespread
in the U.S., is now limited to Puerto Rico and to small
acreages in Florida (Table 9). Current annual usage levels
in Florida are estimated at 1,000 pounds endrin active
ingredient applied to approxiamtely 500 acres of sugarcane
(representing less than 0.2% of Florida cane acreage). This
usage level indicates that endrin is applied to cane on very
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few (possibly only one) Florida farms. Endrin is reportedly
used in Puerto Rico for sugarcane pest control. However, an
evaluation of the impact upon Puerto Rican sugarcane produc-
tion resulting from the potential cancellation of endrin is
not included due to a lack of data regarding current endrin
usage levels.
Several alternative insecticides including azinphos-
methyl, carbofuran, and monocrotophos are registered and
recommended for control of the major cane pest (sugarcane
borer) for which endrin is used. These alternatives have
already replaced endrin in most areas where pesticide
treatments for the sugarcane borer are required. The adoption
of these alternatives on the remaining acreage on which
endrin is used would increase pesticide chemical costs
by $9.20/acre, which represents an increase in production
costs of 2.8% on these acres affected. The total increase
in Florida would total $4,600 per * year. Farm level and
aggregate impacts are not available for Puerto Rico; however,
the increase in per acre production costs shoud be similar
to those projected in Florida. The economic impact of
cancelling this use would be minor.
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Table ^
SWSIARY OF PKP.IMTSAR* BESSFTT JUiAUS!S
ElfDRIN USE UK SUGARCANE
A. USE:
I. .UJOR PESTS CONTROl,! Fl):
C. ALTERNATIVES:
Major Registered Cheinlcsls:
Suu/Mnl SUeoaaendationa:
Noa-CheBUal Controls:
Efficacy of Alternatives!
Caapaiaclve Performance:
Comparative Casts:
Conclusion:
o. mm or rax<
Active lagredlvet Baalai
Dales Treated lull:
Ł. ECOMEBC XXPACBi
Doers
Market, Coaaaaert
Bumtomalei
r. socuuccnomrR mpactsi
c. LOimnoas or ahaltsxsi
E. FUSCirU. ASALTST ASS DATEt
Sugarcane
Sugarcane borer
RPAR Crapounds: Hon*
Hon—RTA&: Axlnpfcoaaethyl, carbofuraa, nenoerntephn*
Eadrla recoaaaad&U In Florid* aad Puerto Rico. ilunber of renjniiondod alternative*: Florida. 5;
Louisiana, 1; Puerto Rico, 3; US DA, 3. Hawaii aao Texas do not have icica r«f n—nijirloiu Car
sugarcane pests.
/
Biological control of sugsresne bo ran aad other peats encouraged la all areas, particularly In
Florida. Loulalana, aad ttaumll.
Alternatives provide good control of evgarcaoa borara vtaao aa Insecticide la required.
Available teat data Indicate comparable levels of control using eadrla aad alternatives.
Pesticide Pesticide Con Tar Acre
aadrta
aslnpteaaethyl
carbofuraa
aaaocrotophos
SI. 91
4.14
S.J1
1.12
Saveral nos-KPAR Insecticides are both registered aad reewuiniei) for uae en augarcaaa to control
sugarcane borara. Alternatives providt acceptable levels of control at reasonable cost. So prable
of alternative availability are anticipated Given the ere 1.1 lncraaaa la rinrsinrt for alternatives
aaaaclarad with tb< cancellation of aadrla.
Approxiaately 1,000 pouada active ingredient applied la Florida; soae eadrla Is usad la Puerto Ueo
but quantity involved is uadeteralned.
Five hundred acres la norlda (lesa than 0.22 of Florida acreage), aa oadaternlaed nuaoer of acres
created la Puerto Rico.
Coat lacraasas for lasaceleldas In Florida eatlaacad at $4,600 par rear, or 39.20 par acre now treated
with eadrla. No change la yield Indicated oa acres now treated with eadrla fallowing adoption of
altarnatlvea. Prodoctloa east increase of 2.62 par acre par rear oa sffaeted acrea. Total user la-
paets in Puerto Ueo uadetoralMd; haiiaear. per acre cast laeact say be slailar to that projected
for Florida.
Bo lapset Indicated
production.
Bo affect* of loportaai
Hat evaluated.
to alaar pattern of eadrla
ice on a aecroecoaoodc level.
use oa angarrana. So change In doaestlc sogar
Preelaa data regarding the ouantlty of endrln cmieatly la uae on C.S. sugarcane is not available;
no use data is available for Puerto Ueo.
Stark A. luttnar, Gcoeoslst
Harsh 1977
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F. Conifer Seeds
Endrin is widely used as a rodent repellent when
conifer tree seeds are applied to prepared forest sites in
the southeastern and western United States (Table 10). It is
the only chemical repellent registered for this use and the
USDA Assessment Team considered it essential for success in
direct seeding on approximately 90 percent of the 160,000
acres direct seeded in a typical year. Until recently
direct seeding has contributed 15 - 17 percent of all
artificial reforestation, the remainder being reforested by
planting nursery grown seedlings. The amount of endrin
reaching the environment ranges from .002 - .015 lbs (a.i.)
per acre, when applied at labeled rates. Most direct seeded
acres receive less than .005 lbs (a.i.) per acre. The total
use of endrin on direct seeding in a typical year ranges
from 500-850 lbs. (a.i.).
Endrin is the only federally registered rodent
repellent presently available. A petition for registration
has been received to apply Mestranol on Douglas Fir Seed,
commonly used in the west. The cost of treating seed with
endrin is less than 10 cents per acre and the cost of
Mestranol, if registered, will be from $5-10 per acre.
The impact of reforesting without the use of
endrin would be approximately $20 per acre for a total
estimated impact of approximately $3 million for a typical
year. (See Table 10 for additional detail).
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Table fO
svmunr cr rKLunaMrv bsetit a-'iu-ysis - cuxtttr seed murTsr
VSE:
KAJem rESTS WKTMUXB:
ALTimTIVSS:
Ma^or^eglsiered^chealeala:
State/TederalraconMndsclone:
Bon-chertcal controlji:
JEJflejejjfjltjrprijsJvMt
Cnj2SSŁ22S_2SSŁSSSSS:
Camaratiwienats:
toncluaion:
enun or rati
Aetlve_^n»redl«nt_toeŁSJ
(pounds a.i.)
(a) Endrln
(b) Altnutiw
IhJjtjjuurikHlti
(a) tadrla
(b) Alternatives
8C0H05CC IMPACTS:
Ours
Marker:
soctAi/ummm impacts:
LTxmnoas or amutsis:
psncipju. AHAtrsT, nox:
For direct seeding of novural conifer creu species by coatlnc *>'i:as
with endrln and other chcnicnls te> pravent conxunption b* rodi-nu.
Deer and harveat sice, wooU and harvest rats.
Nana. Petition to register naetianul b» USDI (or proceccloe of
Itanglas Fir aaad pending.
Apply coating of alxtura of endrln C .32 a.i. by Might of Mad)
with thrlan (oa bird repellent) plus latex sticker (OSDA - PS;
Cal. OtT. Of Perastry).
Nona far Mad protection. Planting aaeriUnga la only alternative
reforestation aeefcod.
Maatraaol (lightly lasa effective for Dooglas fix. Taau oa
Southern Pise thaw loaae* vith aentranol twice that with endrla.
Planting of aaedllnge fives greater aaanraaea of establlabad stand,
better control of stacking and spacing, aad haseands costly auad,
especially from llnltird production of genetically caacrollad saod
eeurcaa.
Use of neatranol increases costs of treated aaad by about 36-310
par aera rod total direct seeding cost by 20-30Z.
Olraet aaadlai for reforestation will practically eeaaa until
affaetlva substitutes ara registered. If aestruol registration
is granted, dinner aeedlns will continue ac 30-405 af currant rates.
Planted seedlings will provide aeaa aabatltuta raforaatatloa.
1973 «I13 pounda. *.1.; 1973 • 4S3 pooada, a.1.
1973 • 1SI.000 acree; 1973 - 100,000 acraa (BStUL, 1976).
Olraet seeding la a vldel» uaad reppltswnt to traa planting, particularly'
.by large corporations for their owi lands aad laada aanatad fnr nthers.
State agencies and federal agencies aiso diract aaad but ieoeral ageneles
ara raatrlctad fras tha uaa of endrln by policy. Planting will ba sub-
stituted for direct seeding oa oany of tha acraa presently aaaaad at a
cost ineraaaa of 12-35 dollars par acre. Tor a typical recent year thlf
coat ineraaaa for planting an estitutad J45.000 meres V.II b? anprexlsatclv
3 alllion dollars. For many ef cnaae arret, where direct seeding i> :)>a
only technically feasible ntchod, direct seeding nay be done at a such
higher coat cslng larger quantities of aaed.
He Iseadlate lapact. Failure to reforest lands for several years
will eventually cause increased wood products supply probleas - "!0-«0
years in th* future. Eroalsn en steep altea aay becoae an incrnaalag
prulilen is not ravegetatad.
Haaa for lvedlata futora.
VU1 require tneraaaad local labor (In short supply) for reforestation
by planing aaedllnga in aroaa affected.
So information la available to predict (1) rwageutlon af altaa not
mfoceatad after harvest er bstulag,
-------
IV. Development and Selection of Regulatory Options
A. Introduction
In Sections II and III above, the Agency identified
the human and environmental risks associated with the use of
endrin and identified the benefits associated with each of its
uses. As explained in Section I, FIFRA mandates the Agency to
achieve a balance between these competing considerations. In
order to accomplish that goal, the Agency has identified
various regulatory options and has evaluated each option
for its impact on both sides of the risk/benefit equation.
This section of Position Document 2/3 describes the
process which the Agency used to develop potential courses of
action for evaluation and identifies the options wihch were
ultimately selected for in-depth evaluation. In Section V,
each optin is evaluated for each registered use of endrin,
and the rationale for the final selection of an option for
each use is set forth.
B. Rationale For Development of Options
In its simplest terms, FIFRA contemplates two basic
options concerning the regulation of pesticides — namely,
to grant or to deny registration. For new pesticide products,
these options are presently in terms of the approval or the
denial of an application for registration; for previously
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registered pesticide products, they are framed in terms of a
decision to either cancel the registration or to allow the
continued registration of the product. Both the denial and
the cancellation of registration represent absolute regula-
tory responses insofar as they unqualifiedly prohibit the
sale or the distribution of the pesticide for the use(s)
at issue.
Registration, on the other hand, represents a range of
regulatory options, since the Administrator may specify the
terms and conditions of the registration. He may, for example,
require the label and the labeling of a pesticide product to
contain certain language — such as warning and cautionary
statements or directions for use — which he considers
necessary for the adequate protection of health and of the
environment. He may also classify the use of a pesticide
product for restricted use, and limit its application to
certified applicators or to persons under their direct super-
vision.
Cancellation and unrestricted registration fall at
opposite ends of the regulatory spectrum. The development
of intermediate regulatory options involves the formulation
(and/or modification) of the terms and conditions of
registration which are intended to reduce the risks attendant
to the use(s) of the pesticide. Each option is then evaluated
on a use-by-use basis to determine whether it achieves an
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adequate reduction in risk without causing unacceptable
economic consequences, so that the remaining benefits of the
use exceed the remaining risks of that use.
C. Velsicol Risk Reduction Proposals
Velsicol Chemical Corporation ("Velsicol"), the sole
domestic manufacturer of technical grade endrin, submitted a
lengthy response to the RPAR on November 4, 1976, and has been
in frequent communication with the Agency concerning the pro-
gress of the RPAR. In July, 1977, representatives of Velsicol
and the Agency met to discuss the possible resolution of the
RPAR process. At the meeting, it was indicated that classi-
fication of endrin for restricted use, together with the
imposition of appropriate label modifications, might be a
feasible disposition of the endrin RPAR. It was suggested that
Velsicol could assist the Agency in its consideration of this
option by collecting and submitting to the Agency expert
technical advice concerning revisions of label directions and
the development of limitations which would enhance the safety
of the application of endrin.
Velsicol subsequently submitted three documents to the Agency
concerning proposed label modifications. On November 11, 1977,
it submitted a package containing certain proposed revisions to
the endrin label, which focused on the use of endrin in apple
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orchards for control of the pine vole and the meadow vole. The
package also contained a compilation of expert opinions on
which the proposed revisions were based, together with an
explanatory summary of the rationale underlying the proposed
changes.
On January 30, 1978, Velsicol submitted a second document,
entitled "Report from the Technical Advisory Committee on Label
Instructions For Endrin-Methyl Parathion 1.6 EC and Endrin 1.6
EC", which contained proposed revisions of the endrin labels
relating to the cotton and small grain uses of endrin, designed
to enhance the environmental and applicator safety of those uses.
The "Technical Advisory Committee" referred to in the document's
title consisted of a panel of cotton and small grain entomologists
and experts on aerial application of pesticides who participated
in a two-day round table discussion at Velsicol's invitation.
The report itself also contained technical background material
which was considered by the panel in formulating its final
recommendations for label revisions.
Finally, on April 11, 1978, Velsicol submitted to the Agency
a formal application for amended registration for two of its
registered endrin products (EPA Registration Nos. 876-153 and
876-127). The applications for amended registration were
accompanied by proposed labeling which synthesized the proposals
previously submitted into a comprehensive package incorporating
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what Velsicol considered to be the consensus of expert advice
about the specific limitations which would enhance the safety
of endrin while maintaining the major benefits of its use.
The Agency has considered Velsicol"s proposed label
modifications in its development of regulatory options for
all registrations of endrin products. To the extent that
the Agency determines that modifications to the terms and
conditions of endrin registrations are necessary to prevent
unreasonable adverse effects on the environment, it will
develop specific label language for incorporation into all
endrin labels; Velsicol*s particular application for amended
registration will then be evaluated for compliance with the
required changes. The Registration Division will also deter-
mine the acceptability of any other additional changes to
the label which Velsicol may propose in its application.
D. Risk'Reduction Methods
The process of developing the regulatory options
designed to reduce the risks accompanying the use of endrin
focused on the routes of human exposure to endrin and on the
routes of environmental contamination from the use of endrin.
Because of the demonstrated teratogenicity of endrin,
the human population of concern to the Agency consists pri-
marily of women of child-bearing age. Women of child-bearing
age may be exposed to endrin in situations "which arise prior
-1-01-
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to, during or after application. Prior to application,
mixers and loaders may be exposed both dermally and via
inhalation as the result of splashing, vaporization or
accidential spills; during application, pilots and flag
persons involved in aerial application, as well as ground
applicators, may all be exposed both dermally and via
inhalation, primarily as the result of drift of the endrin
spray. Finally, both during and after application, bystanders
{i.e., persons other than those directly involved in the
application process) nay be exposed both dermally and via
inhalation as the result of spray drift, and via ingestion
as the result of consumption of food — principally fish --
which contains residues of endrin.
From an environmental point oŁ view, a major problem
is the contamination of fish-bearing waters with toxic
amounts of endrin. Such contamination may occur as the
result of either or both of two processes: drift of the
endrin spray onto water bodies; and run-off of endrin from
soil or foliage into the water bodies, either directly or
via drainage channels. A second problem relating to environ-
mental contamination is the existence of residues of endrin
on plant parts and target species which form part of the
diet of non-target species.
The Agency has considered each of these exposure
situations, and has identified several methods of reducing the
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potential exposures. Each method is generally discussed
immediately below.
(1) Classification for Restricted Use;
Limitation of Ose'to Certified Applicators
Under FIFRA, pesticides may be classified
for restricted use and limited to use only by or under the
direct supervision of certified applicators who have been
determined to be competent with respect to the use and
handling of hazardous pesticide products. Certification
programs are, for the most part, administered by the States.
These programs use various methods to determine that appli-
cators are certifiable as competent to use restricted use
pesticides.
On January 31, 1978, the Administrator classified all
uses of endrin for restricted use, and limited them to use
by or under the direct supervision of a certified applicator
(40 CFR §162.31; 43 FR 5788, February 9, 1978). The uses
were classified under the Agency's Optional Procedures for
Classification of Pesticide Uses by Regulation (40 CFR §162.30;
42 FR 44170, September 1, 1977) (the "Optional Procedures").
As explained in the preamble to the Optional Procedures, the
decision to classify endrin under those procedures was based
on an "incremental" risk/benefit analysis established by 40
CFR §162.11(c), which requires the Administrator to compare
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the incremental benefits of unrestricted use (those over
and above the benefits of restricted use) with the incre-
mental risks of unrestricted use (those over and above the
risks of restricted use). In other words, the Optional
Procedures focused on the risks which could be reduced by
restriction as compared with the benefits which could be
lost as the result of restriction. With respect to endrin
in particular/ the criteria of risk influencing the Agency's
risk/benefit analysis were the acute dermal toxicity of endrin
and the hazard it presents to non-target organisms. The pre-
dominant factor on the benefits side was the determination
that the classification of endrin for restricted use would
not unduly limit access to, or the availability of, endrin
products.
Decisions made in the context of the Optional Procedures
must be distinguished from decisions'made in the RPAR process.
The latter decisions require an evaluation of the overall, as
distinguished from incremental, risks and benefits associated
with the use of any pesticide. In the RPAR context, classi-
fication is appropriate as a regulatory response if it will
avoid the need to cancel a use of a pesticide in a situation
where the overall risks of the use otherwise would exceed
the overall benefits of the use. (42 FR at 44170, September
1, 1977). The preamble to the Optional Procedures stated:
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"Since this optional procedure only involves an
incremental, and not an overall risk/benefit analysis,
a decision under the optional procedure to restrict (or
not to restrict) a use of a product will not in any way
imply that the product will (or will not) ultimately
satisfy the statutory standards governing registration
or reregistration." (Id.)
Thus, the Administrator must reevaluate the adequacy
of the reduction in risk achieved by the classification of
endrin for restricted use in the context of the overall
risk/benefit analysis undertaken during the RPAR process.
(2) Reduction of Dermal Exposure By Use of Protective
Clothing
The populations with the greatest potential dermal
exposures to endrin consist of persons who are directly
involved in the ground application of endrin, and persons
who are involved in the mixing, loading and transfer opera-
tions related to both aerial and ground application.
The Agency has noted that one drop of endrin (1.6 EC) on the
skin, if totally absorbed, is equivalent to an exposure of
10 milligrams of endrin (EPA, 1978b). Since such an exposure
would result in a margin of safety of approximately 10 for
teratogenic effects, the Agency believes that it is both
necessary and prudent to explore means for reducing or
eliminating the possibility of direct dermal contact with
endrin.
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Such reduction can best be accomplished by a requirement
that women involved in these operations wear appropriate
protective clothing. Such clothing is described in Section V.
(3) Reduction of Inhalation Exposure By tJse of
Respirators
Women involved in mixing, loading and transfer opera-
tions and women involved in the actual application of
endrin — including pilots, flag persons in the field, and
other ground personnel —¦ are faced with an additive risk of
teratogenicity from inhalation exposure to endrin.
The Agency believes that significant reductions in
inhalation exposure will be achieved if all such persons
comply with the current requirement to wear full-face
air-purifying pesticide respirators of the type jointly
approved by the National Institute for Occupational Safety
and Health and the Mine Safety and Health Administration.
(4) Reduction of Exposure By Minimization of Drift
As discussed above, drift of endrin spray may result
in human exposure (of by-standers as well as those involved
in application or related operations) and in significant
environmental contamination. With respect to the latter,
drift of endrin spray may result in deposition of toxic
amounts of endrin onto water bodies containing fish, and may
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also result in deposition of endrin on plants and other
organisms which constitute part of the diet of a non-target
species.
The principal factor controlling drift is particle or
droplet size. Any spray technique will ordinarily produce a
range of droplet sizes; drift is the airborne component of
the spray, and may generally be defined as that portion of
the spray distribution which is released in droplets initial-
ly below 100 microns in diameter (EPA, 1978b; Akesson,
1977). Since the number of droplets below 100 microns in
diameter decreases as the overall average droplet size
increases (e.g./ by using a coarse spray with relatively
large average droplet size instead of a fine spray with
smaller average droplet size), one method for reducing the
drift component of endrin spray applications would be to
utilize engineering controls to increase average droplet
size. However, droplet size is also a parameter of the
efficacy of the application, and a larger droplet 3ize may
result in reductions in target coverage. Accordingly,
to the extent that engineering controls are considered as a
feasible method of reducing the airborne drift component of
endrin spray applications, an optimum droplet size distribu-
tion would have to be achieved.
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A second Łactor which affects potential exposure from
the drift of endrin spray is the distance from the point of
application since the amount of drift which is deposited
decreases as the distance from the point of application
increases (EPA, 1978b). Accordingly/ another method
of reducing the potential exposure from drift of endrin
spray would be to prohibit the application of endrin —
depending on droplet size distribution -- within certain
distances from specified areas.
Finally, other factors are relevant to the dispersal of
drift, such as the climatic conditions prevailing at the
time of application (e.g., wind velocity), and the height at
which the spray is released. General limitations and
instructions concerning these factors would also be appro-
priate in order to minimize the potential exposure from
drift.
(5) Reduction of Environmental Contamination By
Minimization of Run-Off
The second, and perhaps more significant, source of
environmental contamination is the run-off of endrin from
treated areas into water bodies. Some run-off may go
directly into the affected water body (e.g., from a treated
field immmedlately adjacent to the water body); other
run-off may be more indirect, going first into drainage
channels that may normally be dry.
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Unlike the situation with drift, engineering controls
on application equipment can not reduce the potential for
run-off. For some uses the potential for run-off may be
reduced by prohibiting application of endrin when rainfall
is imminent and by a prohibition against the application of
endrin within a specified distance from water bodies. In
addition, a distance restriction would reduce the total
number of acres treated with endrin, thus reducing the total
amount of endrin susceptible to run-off.
(6) Reduction of Ingestion Exposure
Although the total dietary burden of endrin residues is
not of concern to the general population, a high potential
for exposure to endrin via ingestion exists for women or
non-target organisms eating fish which have accumulated
either sublethal or lethal amounts of endrin. The best
means of reducing such potential exposure obviously would be
to reduce the occurrence of such residues in the fish; this
in turn would best be accomplished by the minimization of
environmental contamination from run-off and drift.
With respect to other potential food chain exposures,
an additional precaution may be taken — namely, to require
the clean-up of certain endrin-related kills of vertebrates,
both intentional (as in bird control) and accidental, in
order to prevent exposure to predatory animals which might
feed upon the victims.
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E. Regulatory Options Selected
The Agency has selected three general options for
the ultimate registration decision, to be considered and
evaluated in Part V on a use-by-use basis. In selecting
these options, the Agency first chose both the least restric-
tive option — continued registration as a restricted
use pesticide — and the most restrictive option — cancella-
tion of each use of endrin. The Agency then fashioned
an intermediate option between these regulatory extremes,
which focused on modification of the terms and conditions
of registration of each endrin use. In developing this
third option, the Agency necessarily exercised its discre-
tion in its choice and consolidation of terms and conditions
of registration. The Agency believes that these three
options adequately address all of the relevant concerns
relating to the use of endrin.
The alternatives selected are as follows:
(1) Continue Registrations as Restricted Pse Pesticides
Under this option, a use of endrin would be regis-
tered in the same manner and with the same restrictions that
are currently in effect, and no additional regulatory action
would be taken to reduce any risk which accompanies that use
endrin. The use of endrin would continue to be limited to
certified applicators (or persons under their direct supervi-
sion) who have been demonstrated to be competent in the use
and handling of pesticides.
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(2) Modify Terms and Conditions of Registrations
Under this option, the terms and conditions of
registration would be modified for each use in order to
reduce the risks which accompany that use. Generally, the
modifications fall into four major categories.
The first set of modifications are intended to
reduce the risks to the certified applicators involved in
the application process and to women involved in related
operations such as mixing, loading and transfer. Speci-
fically, protective clothing covering essentially all of the
body surface would be required for women during application
and during all phases of mixing, loading and other transfer
operations. The protective clothing would consist of
impermeable gloves, boots or boot covers, long sleeved shirt
and pants, and would significantly reduce the high potential
for dermal exposure during these operations.
The second set of modifications focus on the
cautions and warning statements and other language designed
to educate the user in the hazards associated with the use
of endrin. First, a specific warning to women is necessary
to reduce teratogenic risk. Second, a statement warning
against prophylactic use of endrin should be included for
uses for which unnecessary prophylactic application is a
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common practice. Prophylactic use of endrin may not only
result in unnecessary environmental damage, but may also
reduce future endrin efficacy by increasing target pest
resistance to endrin. Third, appropriate labels should
contain warnings and directions concerning the disposal of
certain vertebrate animals (whether or not they are target
species) which are killed as the result of exposure to
endrin. Such modifications would help prevent the secondary
poisoning of non-target species. Moreover, the label should
contain warnings designed to prevent consumption of fish
contaminated by endrin.
The third set of modifications are specifically
formulated to reduce the risks associated with endrin by
focusing on application techniques and the conditions of
application. In particular, in order to reduce the environ-
mental contamination and human exposures which are associated
with the drift of endrin from target areas, this option
would reduce the airborne drift component of endrin spray
applications by increasing the average droplet size produced
by application equipment. Label directions for use would,
whenever possible, prescribe ranges of noz2le sizes and
nozzle presures on specific types of application equipment
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(both aircraft and ground)? otherwise, they would describe
other conditions.whch would achieve the desired range of
droplet sizes. Further, aerial applications would be
prohibited when wind speeds do not fall within a specified
range, and a maximum height for release of the spray would
be prescribed.
Finally, the fourth set of modifications would
impose, whenever feasible, prohibitions against the use of
endrin within specified distances from designated bodies of
water, human habitations, or other areas requiring protection.
(3) Cancel Registrations
Under this option a specific use (i.e., site/pest
combination) of endrin would be prohibited. Where a crop
is grown under a relatively wide range of environmental
conditions, however, the risk/benefit picture may vary
accordingly. In such circumstances the Agency may conclude
that cancellation is an appropriate option in some areas
while continued registration is appropriate elsewhere.
Where feasible, therefore the Agency may determine that a
partial cancellation of a use on a geographical basis is a
viable option.
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V. Impact of the Major Options
A. Introduction
This section presents and evaluates the regulatory
options for each use of endrin and determines which option
produces the most favorable balancing of the risks and the
benefits of its use.
B. Investigation of the Impacts of Regulatory Options
for Each Use of Endrin
1. Cotton
a. General Information
More endrin is used for cotton than for any
other use. Recent information from Vels.icol (Sec. I) indi-
cates that the use of.endrin on cotton declined substantially
in 1976, but that usage has. remained relatively constant
since then. The information on current use was used to
update the impact analysis.
The importance of endrin as a cotton insecticide
is relatively minor, since the 150,000 acres on which endrin
is used represent less than 1% of the total number of acres
planted with cotton which are treated with insecticides. The
use of endrin as an insecticide on cotton is not a common
practice throughout the Cotton Belt. Instead, its use is
concentrated in the States oŁ Alabama, Arkansas, Florida,
Georgia,,and Mississippi (EPA, 1977a). Although EPA cur-
rently registers endrin for use on numerous insects (see
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Sec. Ill), its primary use has been to treat the tobacco
budworm (Heliothis virescens) and the cotton bollworm
(Heliothis zea). Onlytwo states, Mississippi and Alabama
recommended the use of endrin on cotton in 1978/ specifically
for the control of Heliothis. EPA currently registers a
total of 18 pesticides for the control of bollworms (Thomas,
1978). Five new pesticides, including synthetic pyrethroids,
have pending registrations.
b. Comparative Risks of Current Use
(1) Human.
The risks to humans from the use of endrin on
cotton are limited essentially to the potential teratogenic
effects which may be caused by exposure to drift from nearby
fields during treatment and from eating fish which are
contaminated with endrin (Sec. II). The margins of safety
associated with such exposure (880 and 375, respectively)
indicate that some teratogenic risks to humans could reasonably
be anticipated.
The major alternative to endrin, EPN, is under
RPAR review because the Agency has reason to believe it
causes neurotoxic effects and may cause irreversible eye
problems in humans. EPA has issued a RPAR of the second
most likely alternative, toxaphene, because it appears
to cause oncogenic effects in rats and mice. The assessment
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of the risks for these effects is not yet available The
other most likely substitutes for use on bollworms, acephate,
monocrotophos, and methomyl, do not appear to have toxico-
logical properties that meet or exceed RPAR criteria for
risks to humans (Burnam 1978a). The use of these alterna-
tives could reduce risks.
(2) Fish and Wildlife
As indicated in Section II, endrin is highly
toxic to fish and other aquatic organisms. The predictable
relationship between the use of endrin on cotton and fish
kills is verified by PERS reports. This adverse effect is
recognized by users (Sears, 1978). However, the information
which is available does not permit an accurate quantification
of the frequency and the magnitude oŁ the fish kills in
relation to the use of endrin. Although the Agency concurs in
the assessment of the FWS (Greenwalt, 1978) that the use of
endrin has not jeopardized the continued existence of the
brown pelican, it concludes that a substantial potential
for risk to this endangered species nevertheless does
exist, since the concentrations of the residues of endrin
which were found in the dead brown pelicans (up to 0.7 ppm
in the brain) are so close to the concentrations which are
known to be lethal for other species of birds (0.8 ppm and
greater).
EPN, the most likely alternative to endrin
for use on cotton, poses less of an acute risk to aquatic
organisms then does endrin. However, EPN has a relatively
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high potential for causing chronic effects in aquatic
invertebrates. The Agency has found that these chronic
effects are not readily assessed (Bushong, 1978). The Agency
judges EPN to be less hazardous than endrin for terrestrial
organisms (Bushong, 1978).
The Agency has issued a RPAR of toxaphene, the
next most likely alternative, because its use causes reduc-
tions. in the populations of nontarget aquatic, avian, and
mammalian species. Compared to endrin, the use of toxaphene
on cotton has less potential for causing acute effects in
aquatic organisms, but its greater persistence in the
environment and the fact that it causes chronic effects
in fish appear to make the total risks from toxaphene equal
to or greater than those of endrin (Bushong, 1978). Similarly,
while limited field evidence suggests that endrin may be
more acutely hazardous than toxaphene to terrestrial organisms,
more bird deaths are anticipated to occur from toxaphene-laden
fish than from endrin-laden fish based on incident records
and accumulated data (Bushong, 1978). Hence toxaphene is not a
desireable substitute for endrin from an environmental point
of view.
The information on other alternative pesticides
which is necessary to assess comparative risks is generally
less adequate than that for toxaphene. Using laboratory
data as a basis, EPA scientists have judged that acephate,
monocrotophos, and methomyl pose less of an acute risk to
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fish and to aquatic invertebrates than endrin. The risk of
chronic effects occurring in aquatic invertebrates from the
use of methomyl is relatively low. The Agency has not yet
found it possible to assess the risk of of chronic effects
from the use of acephate (Bushong, 1978). The Agency
expects that the use of monocrotophos on cotton would cause
a significant increase in avian mortality and that the use
of both methomyl and EPN would be safer materials for
terrestrial verebrates than endrin. The Agency has not
yet found it possible to assess the risks to terrestrial
vertebrates from the use of acephate (Bushong, 1978). In
summaryf the Agency believes that the information which is
currently available indicates that substituting toxaphene
for endrin for use on cotton would not reduce the risks to
fish and wildlife, but that a substitution of a mixture of
the other alternative pesticides would do so.
c. Benefits of Current Dse
In order to assess the benefit which endrin
provides for controlling the cotton pest, Heliothis it is
necessary to predict which practices of pest control farmers
would most likely use to replace endrin if it were not
availble. The Agency measures the benefit which endrin
provides by comparing the costs of using endrin with the
costs of using its alternatives.
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First, it is necessary to identify those
practices and second, they must be allocated over the
current endrin treated acreage. Several insecticides are
available if endrin were cancelled. Of the RPAB. choices,
toxaphene and EPN are the most commonly used. The most
likely candidates from the non—RPAR group include mono-
crotophos and methomyl.
The acreage distribution of these alternatives
was obtained from their proportional use based upon data
from Mississippi (See Section III B). To summarize, the
alternative insecticides and the treatment acres used to
estimate benefits are as follows:
Treatment Acreage Replacing Endrin
Insecticide AC. % of Endrin Acreage
Toxaphene 178,125 25
EPN 399,000 56
Monocrotophos 78,375 11
Methomyl 42/750 6
New Insecticides 21,375 3
available under
Sec. 18
The benefits of endrin can be estimated by
analyzing changes in the costs and yields associated with
the use of the alternatives. The investigation of cost and
yield changes are presented in Section III.
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(1) The average increase in cost per each
treatment is $1.00.
(2) The average increase in cost per acre
which includes all treatments in the season is $4.75 or less
than 3% of total production costs.
(3) The average increase in cost per farm
per year is $815.00.
(4) The total increase in cost to all cotton
growers is $717,850 per year.
(5) No improvement in yields can be expected
from endrin compared with the alternatives.
In summary/ due to the combined effect
of small savings in cost and the few number of farms and
acres so affected, the following can be concluded about
endrin's benefit in cotton production:
1. There will be no change in cotton
prices or supply due to the presence or absence of endrin.
Therefore, no adverse effects would occur in overall agricul-
tural production and no adverse effects would occur to
consumers of the final products made of cotton if endrin1s
use were cancelled.
2. There are small savings in costs to
cotton farmers who use endrin. Since the national supply
and the price of cotton will remain unaffected, the costs of
a cancellation will accrue only to the users of endrin.
In conclusion, the use of endrin as an
insecticide on cotton is minor. Its absence would alter
neither the national supply nor the price of cotton.
The affected persons would be limited to a few users and the
manufacturer.
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d. Impacts of Alternative Regulatory Options
1. Option 1: Continued Registration with
No Further Restrictions
The Agency classified endrin for restricted use
in 1978. Any possible impact of this classification must be
considered in the risk/benefit analysis. Endrin has not
been readily available for use on cotton except to those
users who seek certification. The Agency generally expects
the certification program to encourage greater responsibility
on the part of applicators, which would thereby reduce the
occurence of adverse effects. However no substantial reduction
in run-off potential can be expected from this classification
alone. Since run-off is the major route of exposure to
fish, this option is not sufficient to adequately address
the concerns for the risks to aquatic populations, the
subsequent teratogenic risks to humans and the teratogenic
risks to female applicators.
Under this option, the benefits of endrin would
not be changed because no real restrictions which are likely
to reduce its allowed uses or the acreage treated have been
imposed.
2. Option 2; Continued Registration with
New Restrictions
To assess this option, the Agency evaluated
the impact of each of the sets of label modifications
described in Part IV of this document. The types of restric-
tions assessed included worker safety requirements, applica-
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tion directions, distance restrictions from bodies of water
and human habitation, and warnings with respect to the risk
of teratogenicity.
(a) Protective Clothing and Respirators
The Agency determined that requiring
female mixers, loaders, flagpersons, and applicators to wear
more specifically defined protective clothing and respirators
than the current labels require would reduce dermal and
inhalation exposures (EPA, 1978b). The following additional
clothing and respirator requirements were assessed for their
impact on mixers and loaders, flagpersons, and ground
applicators as appropriate: closely woven clothing with long
sleeves and long pants, impermeable boots and aprons,
full-face respirators of the type jointly approved for
pesticide spray applications by the Mining and Safety
Administration (formerly the U.S. Bureau of Mines) and by
the National Institute for Occupational Safety and Health
and wide-brimmed hats.
The economic impact of the above require-
ments is likely to be insubstantial. The clothing and
respirators are inexpensive and since current label restric-
tions impose restrictions upon method of application,
it is likely that many applicators already own the equipment
and clothing evaluated here.
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(b) Cautionary and Warning Statements
The Agency assessed the impact of
additional cautionary and warning statements of the following
types: warnings with respect to excessive use of endrin and
warning with respect to the teratogenic effects of endrin.
The teratogenicity warning would state:
Warning to Female Workers
Excessive exposure to endrin may cause birth
defects. Female workers must be sure to wear
all protective clothing and equipment specified on
this label. In case of accidental spills or other
unusual exposure, cease work immediately and
follow directions for contact with endrin.
The Agency believes that some reduction in risk .
will be achieved by the education of the user about the
potential effects of unnecessary use of endrin and about the
possibility of secondary poisoning of humans and non-target
speciies. The cost associated with these risk-reduction
measures would be negligible.
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The warning with respect to teratogenic effects
would reduce risks to female applicators who may be pregnant
by requiring the use of more specific protective clothing
and respirators. The cost of this restriction, too, would
be minimal.
(c) Equipment and Application Directions
The Agency considered the impact of directing that
application be made only when wind .velocity is between 2 and
10 mph and containing the following instructions:.
Aircraft Applications; Do not apply at less than
2 gallons total mixture of water and chemical per
acre. Do not operate nozzle liquid pressure
over 40 psi (pounds per square inch) with no fan
nozzle smaller than 0.4 gallons per minute (gpm)
or fan angle greater than 65 degrees such as
type 6504. Do not use any cone type nozzles
smaller than 0.4 gpm nor whirl plate smaller than
#46 such as type D4-46 or no other atomizer
or nozzle giving smaller drop size. Do not
release this material at greater than 10 ft.
height above the crop.
Ground Applications; For use with boom-nozzle
ground equipment. Apply at not less than 5 gallons
total mixture, water and chemical, per acre. Do
not use nozzle liquid pressure at greater than 40
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psi (pounds per square inch). Do not use cone
nozzle size smaller than 0.16 gpm at 40 psi such
as type D2-25 or TX-10, or no other atomizer or
nozzle giving smaller drop size.
d. Distance Restrictions, The Agency considered
prohibiting application of endrin within areas adjacent to
water bodies and human habitation as a possible regulatory
option. The questions raised in any consideration of dis-
tance restrictons are: "How much acreage will be excluded
from treatment by various distance restrictions? To what
extent can risks from drift and run-off be reduced by a
distance restriction from bodies of water? To what extent
would benefits be reduced by a distance restriction?
The Agency attempted to evaluate the impact
that a distance restriction would have on treatable acreage
by the following methods. The Agency asked extension
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personnel Łrom the States of Alabama, Arkansas and Missis-
sippi (the major areas of endrin use on cotton) to identify
two areas within their respective states where the restric-
tion on distance from water would have the most and the
least influence on treatable acreage. U.S. Geological
Survey 7.5 min. topographic maps were then used- to locate 25
sq. mi. plots covered by aerial photographs on file at the
Environmental Photographic Interpretation Center (Holtorf,
1978). The proportions of the total cropland located within
1/8 and 1/4 miles of water bodies were then measured.
The results of the above procedures indicated
that, even in areas judged to be least affected by the
restriction, about 65% of the acreage would be eliminated at
1/8 mile and more than 90% at 1/4 mile. Under the criteria
employed to define water, which included intermittent
streams, it is clear that a 1/4 mile restriction in these
cotton states would be tantamount to a cancellation since
the restriction effectively eliminates virtually all treatable
acreage.
On learning of the Agency's results, Velsicol
engaged Dr. Norman B. Akesson to reassess the Agency's
results employing a more conservative definition of "any
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body of water" and included "only perennial bodies of water
and not intermittent streams, ponds or drainage systems"
(Ebner, 1978). Thus, in five of the areas previously
analyzed by the Agency, Akesson (1978) estimated that from
30 to 90 percent of the total land area could be treated
while maintaining a 1/4 mile distance from bodies of
water as defined. The average treatable acreage was 62
percent and this deviates substantially from the Agency's
estimate of less than 10 percent. Velsicol's estimate,
however, is probably too low because, among other reasons,
ponds were not included in the analysis.
In order to reach the conclusion that a
1/4 mile distance restriction would reduce substantially the
risk of endrin to aquatic organisms, information would be
required on the extent of past and current application
practices in the 1/4 mile zone and on the extent to which
transport by drift and by run-off would be reduced.
Available data permits realistic approximations of the
impact of a distance restriction on drift reduction to
be calculated, and this data indicates that a distance
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restriction can substantially reduce contamination of water
from drift. (EPA, 1978b). Further, a distance of about 150
yards from the point of application would increase the
MOS to approximately 5500, and this provides an ample
margin of safety from the teratogenic risk associated with
drift.
For the cotton use, run-off, rather than
drift, is the principal source of contamination. The Agency
does not have information showing the impact of a distance
restriction on runoff reduction. The Agency has information
indicating that to bring endrin concentrations in water to
below lethal concentrations for the most sensitive species
of aquatic organisms, a distance restriction would have to
reduce concentrations of endrin in water 1000-fold (EPA,
1975). In the absence of data to the contrary, the Agency
must assume that a 1/4 mile distance restriction would not
reduce significantly the risk to aquatic organisms associated
with run-off of endrin in areas of high rainfall.
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3. Option 3: Cancellation
If the registration of endrin for use on cotton
were to be cancelled, the risks and benefits associated with
this use would be eliminated. EPN and toxaphene are the
most likely substitutes for endrin and several potential
risks attributed to these compounds have been identified.
The Agency is currently assessing these risks but their
significance is not now known. EPN may cause nerve damage,
eye problems and adverse effects on aquatic organisms.
The Toxaphene RPAR Notice cited oncogenic effects in rats
and mice, other chronic effects and reductions in nontarget
populations of aquatic, avian and mammalian species. Non-
RPAR alternatives (methomyl, acephate, and monocroptophos)
do not appear to meet the RPAR criteria for risk for health
effects, although some environmental risks could be expected
(Bushong, 1978). On balance, the cancellation of the
registration of endrin for use on cotton is likely to result
in a net reduction of risks.
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4. Selected Options; (a) Option 3; Cancellation
of Registration for Use in Areas with High
Potential for Aquatic Contamination; (b)
Option 2: Continued Registration with New
Label Restrictions for Areas with Low
Potential for Aquatic Contamination
Cotton is grown under a wide range of climatic
conditions/ and the potential for contaminating bodies of
water from the use of endrin is not uniform. While the
Agency's major analysis focused on the use of endrin in
Alabama, Arkansas and Mississippi, where risks from runoff
are high, some endrin is used in areas such as Oklahoma
(Sears, 1978) where this risk would be lower.
The potential for aquatic contamination is a
function oŁ both run-off potential and the relative abundance
of fish-bearing waters. In delineating this area of concern,
the Agency took several factors into account: run-off
potential (Stewart, 197S); the existence of fish-bearing
waters; the geographic distribution of cotton-growing areas;
and the feasibility of establishing enforceable demarcation
lines. In general, the Agency determined that the potential
for aquatic contamination is greatest in the southeastern
United States and least in the southwestern United States.
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(a) Cancellation of Registration for Use
in Areas with High Potential for
Aquatic Contamination
The Agency reviewed the option to continue
registration without further restrictions on the label and
rejected it. Current use practices result in large numbers
of fish kills. The presence of fish kills implies a probable
teratogenic risk to women of child-bearing age who eat fish
contaminated with endrin. The benefits of continued use
were found to be quite small and to accrue only to users.
However, these users have several viable alternatives. To
some unknown amount, the benefits of use are offset by
residues of endrin in the soil translocating to oil crops,
by adverse effects to commercial catfish, and by any decline
in recreational fishing associated with endrin contamination.
In view of the relatively small benefits, the risks were
found to be unreasonable under this option.
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The Agency considered numerous restrictions
short of cancellation to reduce the risk from the use of
endrin. The Agency's major risk concern is the contamination
of water from the run-off of endrin and the subsequent
impact on aquatic life and on women of child-bearing age who
may eat fish contaminated with endrin. The Agency considered
various restrictions on the distance from the point of
application to bodies of water.
The Agency has concluded that there is no
factual basis for determining that a reduction in risk from
run-off associated with the distance restrictions considered
would significantly reduce the risk to fish and other
aquatic species. The Agency estimates that a 1/4 mile
distance restriction would preclude the use of endrin on a
high percentage of acreage treated with endrin (Holtorf
1978). The Agency finds that a distance restriction would
take away a substantial portion of the present low benefits
from the use of endrin on cotton.
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The Agency has decided to cancel the registra-
tion of endrin for use on cotton areas with high potential
for aquatic contamination. The Agency believes that the use
of endrin in these areas will result in substantial reduc-
tions in populations of fish and other aquatic organisms and
carries with it a risk to pregnant women from eating endrin-
contaminated fish. The Agency has concluded that no feasible
regulatory option less severe than cancellation will result
in reductions of these risks to acceptable levels.
Accordingly, use of endrin on cotton is cancelled
in the following areas: all states east of the Mississippi
River, Arkansas, Louisiana, Missouri, and east of Interstate
Highway #35 in Oklahoma and Texas. Interstate Highway #35
was selected as a demarcation line because it approximately
separates the regions of high and low risks, and because it
is an enforceable and recognizable boundary line.
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(b) Continued Registration with New
Label Restrictions for Areas
with Low Potential for Aquatic
Contamination
In areas of low potential for aquatic contamina-
tion there is some risk to aquatic organisms from drift
and runoff to pregnant women from drift, and from ingestion
of contaminated fish. The current level of benefits is
relatively low. The Agency proposes that registration for
use on cotton west of Interstate Highway $ 35 be continued
with new restrictions. The Agency has determined that the
benefits of use will exceed the risks only if new restric-
tions are proposed.
Because the use of endrin on cotton in areas
with low potential for aquatic contamination and its use on
wheat pose similar risks, the same restrictions should
apply to both uses. These restrictions will be discussed
below in greater detail (pp. 144-148).
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2. Small Grains
a. General Information
Historically, wheat and other small grains
have ranked second to cotton in terms of pounds of endrin
applied annually. The most recent estimates indicated that
up to 250,000 pounds of endrin are applied to treat 1.1
million acres of wheat each year (EPA/ 1977a). The applica-
tion rate for wheat is approximately two-thirds that of
cotton or 0.25 pounds of active ingredient per acre. Outbreaks
of the major target pests (army cutworm, Euxoa auxiliaris and
the pale western cutworm, Agrotis orthogonia) at economic
thresholds are not yearly occurrences on all acreage subject
to infestation and endrin is generally applied only in response
to imminent damage by pests (EPA, 1977c).
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The use oŁ endrin on wheat appears to be
limited primarily to the major wheat-growing states of the
mid-west. The states identified in the Benefit Analysis are
.Colorado, Idaho, Kansas, Montana, Nebraska, Oklahoma, South
Dakota and Wyoming. For control of the army cutworm, two
additional insecticides are registered. These insecticides
are toxaphene, currently under RPAR review, and endosulfan.
Although the army cutworm infests more acreage than the pale
western cutworm (690,000 acres and 415,000 acres, respectively),
the latter pest is of greater concern because no federally
registered alternative pesticides currently exist for its
control.
b. Relative Risks of Current Use
(1) Cutworms. The main basis for the Agency's concern, as
indicated above (Sec. II), resulted from emergency control
for an outbreak of army cutworms in Kansas and Oklahoma
in 1976 and alleged misuse by aerial applicators not familiar
with the region. Additionally, residues of endrin found in
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certain bald eagles (Section II) suggest that local fish
kills from the use of endrin on winter wheat are probably
not rare. To the extent that humans may consume fish bearing
high concentrations of endrin residues, some teratogenic
risk (MOS=360) is to be expected (Burnam, 1978c). Excessive
exposure from drift is unlikely from this use for reasons
cited previously in Section II.
There are no registered alternatives for
control of the pale western cutworm. For the army cutworm,
toxaphene is the alternative in most widespread use, and, in
addition to being a possible oncogen, its risks to fish and
wildlife may equal or exceed those of endrin. Endosulfan
is judged to be a safer alternative (Burnam, 1978a, Bushong,
1978) but this compound has not been used extensively on wheat
(EPA, 1977c).
(2) Chinch bugs. The use of endrin to control chinch
bugs in barrier strips poses no special exposure problems
for applicators or bystanders. The use of protective
clothing is sufficient to reduce the teratogenic risks to
acceptable levels. Contamination of water by drift is
essentially precluded since the strips lie between two areas
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of cropland and application is by low pressure ground
equipment. However, a fish kill associated with this use
occurred in 1978, following a 3-inch rain (J. Stewart,
Velsicol, pers. comm.). Some risk to wildlife is probable
(Bushong, 1978) especially since the timing of the applica-
tion in early summer coincides with the presence of young
birds that feed mainly on insects.
Alternatives to endrin for controlling
chinch bugs on wheat include methyl parathion, parathion,
and toxaphene whose risks to wildlife might approximate
those of endrin. The purpose of the barrier strip is to
reduce the migration of chinch bugs from wheat to other
crops, especially sorghum. Since endrin is not registered
for use on sorghum, pesticides registered only for use on
sorghum are not alternatives for endrin on wheat.
(3) Grasshoppers. A single state registration (Montana)
for this use existed at the time the RPAR Notice was issued.
Velsicol has defended this use (Ebner, 1977). Under Section
24(c), several State registrations for grasshopper control
on wheat and non-crop land were received by the Agency in
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1978. Velsicol's labels for these new registrations impose
1/4 mile distance restrictions from bodies of water and
habitation for humans and domestic animals. Such restrictions
virtually preclude excessive human exposure, but the Agency
is concerned with possible hazards to wildlife that may
consume contaminated insects and with residue levels that
may exist in game birds consumed by humans. No firm basis
for this concern is available. The Agency is assessing
the possibility of monitoring wildlife species associated
with grasshopper control (Kutz, 1978) and will use any
such information in a future assessment of risks from this
use.
Alternatives for grasshoppers are malathion,
parathion, phorate, and toxaphene.
(4) Undefended Pests. Endrin 1.6 EC labels also include
armyworms, fall armyworms and cutworms. The use of endrin
to control these pests was not defended by any-response to
the RPAR notice. Risks from these uses appear to be similar
to other uses on wheat.
Alternatives for armyworms are malathion/
methyl parathion, parathion, toxaphene, and trichlorfon.
Trichlorfon is RPAR candidate under review for possible
oncogenicity in mice, teratogenicity in rats, mutagenicity
in microorganisms, and possible bone marrow effects.
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Alternatives for fall armyworm are methyl
parathion, and toxaphene. Alternatives for "cutworms" include
endosulfan (army cutworm), methyl parathion, parathion,
(including climbing cutworms), toxaphene (including climbing
and surface feeding) and trichlorfon (variegated and surface
feeding). With the exceptions of toxaphene and trichlorfon,
which are under review, the other alternatives appear to
pose less chronic risk to humans than endrin.
(5) Pests Listed on Endrin-methyl parathion formulations.
Pests included on various endrin-methyl parathion labels and
controllable by methyl parathion alone include aphids,
greenbugs, winter grain mites, brown wheat mites, barley
thrips, false chinch bugs, Say plant bugs and leafhoppers.
The Agency is not aware that the presence of endrin contri-
butes significantly to the efficacy of methyl parathion for
the control of these pests (Ludvik, 1978i) and the use of
endrin to conrol these pests was not defended in any response
to the RPAR notice. Methyl parathion alone is not known to
have a teratogenic potential (Burnam, 1978a) and thus has a
lower risk potential than endrin. Risks to fish and wildlife
from methyl parathion are generally less than for endrin.
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c. Benefits of Current Use
In the Benefit Analysis, investigations of
economic impacts were conducted separately for the army
cutworm and the pale western cutworm (EPA, 1977a). The
comparative cost analysis for control of the army cutworm
provided the following estimates for replacing endrin with
alternatives (1976 costs):
1. Total increase in cost per treated acre
per year - $1.66-1.94 (only one treatment
per season is applied)
2. annual increase in cost per farm during
years of army cutworm infestation 5332-388
3. total increase in costs per year
$1.1-1.3 million
The unavailability of endrin to control the
pale western cutworm would result in no pesticide treatment
since there are no other federally registered pesticides for
this pest.
The effects of a cancellation of endrin on
wheat yields and quality were investigated. For control of
the army cutworm no yield or quality effects were expected
with the switch to alternative controls. Since there are
no alternatives for the pale western cutworm, yield loss
would be expected. During years of low infestation yield
losses were estimated to be between 2.4 to 4.2 bushels per
acre on the infested acreage. In years of high infestation,
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which occur relatively infrequently, yield losses could be
15 bushels per acre. No effect on quality of wheat would be
expected. The added cost per acre per year would range from
$26 to $44. On a per farm basis added costs would vary from
$7000 to $16,000 per year.
In summary, the total increased costs due to
the increased cost of pest control and to lower yield would be
about $15 million on an average annual basis. The loss in
total wheat production, 0.28 percent of the national crop,
would have an inperceptible impact upon the price of wheat as
would the maximum annual loss of 1.5 percent. As a result
there would be no effect on consumer prices of products made
from wheat. In summary, the impact of a cancellation accrues
to the user of endrin.
The function of a barrier strip is to
reduce the movement of chinch bugs from maturing wheat into
other crops, especially sorghum. The merits of this use
rest solely on the extent to which such treatment reduces
the need for treating the crops to be protected. The Agency
has no basis for concluding that a single application of
endrin in a barrier strip reduces the movement of chinch
bugs so effectively as to substantially reduce the need for
treating the protected crop and therefore believes that the
benefits from this use of endrin are very small. The use
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was defended only by Dr. Leroy Brooks (1976) of Kansas and
the absence of more widespread support suggests that this
use is not considered to be generally important (Ludvik,
1978 g and k).
The use of endrin to control grasshoppers in
Montana was defended by Velsicol (Cbner 1978) and by users
(Ludvik, 1978 d and f). The widespread eruption of grass-
hoppers in 1978 has elicited additional concerns for this
use of endrin. The Agency has no data which can be used
to evaluate the benefits conferred by this use of endrin.
The use of endrin to control armyworms, fall
armyworms, cutworms, and the several pests listed on certain
endrin-methyl parathion formulations were not defended. In
the absence of relevant information, the Agency assumes that
the benefits from these uses if endrin are negligible.
d. Impacts of Alternative Regulatory Options
(1) Option 1: Continued Registration with
No Further Restrictions
Risks to fish and consequent risks to wildlife
and humans from control of army and pale western cutworms on
wheat are mainly associated with drift. It is expected that
restricted use classification will help to reduce risk due
to drift by informing the applicators of the concerns.
However, winds of 10 mph or greater are common in the Great
Plains where endrin is used. Growers apply economic thres-
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hold techniques as a guide to timing endrin applications,
waiting until damage is apparent from these cutworms before
treating (EPA, 1977c). As a consequence, endrin may need to
be applied when wind conditions are unfavorable.
The benefits of continued registration
are as outlined above. Briefly, the benefit is primarily to
the user in terms of both savings in total production costs
and gains in income from higher yields. In summary, a
principal use of endrin would be maintained but exposure to
endrin, primarily from drift, remains.
Continued registration for use on chinch
bugs would expose wildlife along crop borders to large
numbers of dead and dying insects and occasional run-off from
summer storms is possible. The benefits from this use appear
to be negligible.
Lack of information on the risks and benefits
of continued registration for grasshopper control has prevented
a final assessment. Risks to man and to the environment from
the use of endrin to control other pests have not been balanced
by demonstrable benefits.
(2) Option 2: Continued Registration with
New Restrictions
Improved requirements for protective cloth-
ing and the addition of a warning statement can reduce
teratogenic risks to workers. These requirements are at
pages 122-124. Improvements in equipment and applica-
tion directions indicated on pages 124-125 can help to
-------
control drift. Restricting application to within 150 yards
of human habitation will limit dermal exposure and therefore
teratogenic risks to bystanders to an ample margin of
safety. In the Great Plains, drift rather than run-off is
the major factor contributing to water contamination
(Coppage, 1978). A 1/4 mile restriction would limit risk to
all but sensitive species in shallow ponds or marshes (EPA,
1978b, Coppage, 1978). It is the Agency's opinion that this
distance restriction should be applied to permanent streams,
lakes, public waterways and commercial fish ponds. Private
ponds are intentionally excluded from the restriction but
are to be protected by the label precaution, "Application
within 200 yards of ponds may result in fish kills."
The rationale for exempting private ponds
from any distance restriction is that most such ponds
are owned by the grower (Coppock, 1976). In general, the
value of the wheat protected within 1/4 mile of a pond
may greatly exceed the value of the potential fish loss and
the Agency believes that the grower should have the option
of choosing between fish and wheat when these are both
owned by the same individual.
However, fish kills pose a potential for
causing additional adverse effects to bald eagles and to
such other forms of wildlife which may be attracted to the
dead fish. In addition, surviving fish may bear residue
levels that pose teratogenic risks to humans. Accordingly,
the Agency believes that the following statements should be
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included on the label, "In case oŁ accidental fish kill,
fish must be collected promptly and disposed of by burial."
and "If ponds have been contaminated by drift or runoff,
post No Fishing, Contaminated signs for a one-year period."
A period of one year provisionally is based on the fact that
endrin is absorbed by particulate matter and deposited in
sediments, and contaminated fish lose endrin residues rather
rapidly when placed in clear water in the laboratory (Argyle
et al, 1973). The rate of residue elimination in the field
is unknown but three or four months after the 1976 Kansas
episode, some fish still contained up to 0.3 ppm endrin
(Kloepfer, 1976).
Under this option, the benefits are largely
maintained as presented in continued registration. It is
anticipated that most of the restrictions can be achieved at
little or no cost. Since the purpose of the restrictions
is to protect applicators, mixers and loaders, adequate
compliance is expected if a teratogenic warning is present.
The only restriction which would impose increased costs is
the 1/4 mile distance limitation. A preliminary study
assessed the impact of this restriction on wheat (Zygadlo,
1978) and concluded that, at the very most, less than 10% of
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the current endrin treated acreage would be affected. The
expected amount of acreage affected is about 2 to 3% and the
cost associated with this amount of acreage is small although
not quantified. Thus, this restriction is feasible for the
majority of wheat farmers and is a viable choice of options
for the Agency.
Where endrin is the pesticide of choice,
alternate compounds are not likely to be used on most of
the wheat acreage if the use of endrin were to be prohibited.
The reasons for this conclusion are that no other pesticides
are registered for the pale western cutworm and, on army
cutworm, toxaphene is less efficacious in cold conditions
(EPA, 1977c). Additionally, the 1/4 mile distance restric-
tion does not impose a total reduction of treatable acreage
within that distance but rather an incremental reduction.
Present labeling precludes use within a distance from water
judged by the applicator as sufficient to avoid adverse
effects. Thus, it seems likely where endrin is the chemical
of choice that some acreage will simply go untreated rather
than having endrin replaced by toxaphene. A net reduction
of risks will be obtained in this situation.
In summary, this option allows use of
endrin for army and pale western cutworms at a small
increase in costs. But these additional restrictions would
be expected to reduce risk. Special label restriction that
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would reduce risks from the control of chinch bugs and
undefended pests are not apparent. Contaminating insects
that may be fed upon by wildlife is an inevitable consequence
of treatment. Intense summer storms are not predictable and
it seems unlikely that any distance restriction will slow
the runoff from a cloud burst.
(3) Option 3: Cancellation
The risks to humans and to the environment
due to endrin would be eliminated for all pests. About 40%
of the acreage currently treated is infested by the pale
western cutworm and no pesticides would be used. On the
remaining 60% of the acreage, toxaphene is the likely
alternative and risks from the use of this pesticide may
equal or exceed those of endrin. The loss in benefits due to
a cancellation on pale western and army cutworms would be
significant to the user group. Cancellation of chinch bug
control would result in a very low loss of benefits since
this use is little practiced and is of questionable value in
areas where it is employed. Cancellation of undefended
pests would have no known effect on benefits.
(4) Selected Options: (a) Option 2: Continued
Registration With Label Restrictions for
Pale Western and Army Cutworms and for
Grasshoppers;(b) Option 3: Cancel Registra-
tion for Chinch Bugs and All Undefended
Pests
Option 2 is selected because the use of
endrin is important to those farms which experience out-
breaks of the target pests. The savings in costs and
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gains in revenue are significant to these individual farms.
The most important benefit of endrin is its effectiveness
is controlling the pale western cutworm. It was estimated
that the overall risk associated with the use of endrin is
relatively low under current use practices. With the addi-
tional restrictions, that risk is even lower.
Option 3 is selected because the risks to
humans and to the environment are not balanced by any
demonstrable benefits.
3. Apple Orchards
a. General Information
Apple orchards rank third in total yearly
usage of endrin; approximately 85,000 pounds are applied
to 58,000 acres. Endrin is used to control the pine vole
(Microtus pinetorum) and the meadow vole (Microtus pennsyl-
vanicus in the east and primarily H. montanus in the West).
Endrin may be applied once annually, post-harvest. The major
states using endrin are Georgia, South Carolina, North
Carolina, Virginia, Maryland, West Virginia and Pennsylvania
in the East and Washington and Idaho in the West.
b. Risks of Continued Use
(1) Human
Judging by measures of applicator exposure
to endrin in the orchards of Washington State (EPA, 1978b)
unprotected female applicators of child bearing age may be
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subject to a high level of teratogenic risk (MOS of 75,
Burnam, 1978c). Current use by certified applicators in
conformance with label directions for protective clothing,
however, should reduce that risk by a factor of five to an
MOS of 375 (EPA, 1978b) but this is still cause for concern.
Except for applicators, exposure from this use appears to be
below the level of concern, assuming compliance with label
precautions.
(2) Fish and Wildlife
Endrin residues designed to kill mice are
intuitively hazardous to other forms of wildlife that feed
on the ground vegetation in orchards. Theoretical calcula-
tions support this conclusion (Barbehenn, 1976; Bushong
1978). Apparently the only systematic monitoring to detect
effects on wildlife was conducted in the fall of 1977 in
New York State. A report of the results is not yet available.
The high rate of application (up to 2.4 lbs/acre) provides a
potential for fish kills when runoff conditions are present.
This potential has been verified in reports from North Carolina
and Pennslvania (Sec. II).
The major federally registered alternative
to endrin is zinc phosphide baits. These baits pose some
demonstrable hazard to pheasants and rabbits but potential
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effects on aquatic systems cannot be assessed with available
data (Bushong, 1978). Information on DPN and CPN is generally
inadequate to assess comparative risks.
c. Benefits of Continued Use
Endrin provides the most economical means
of rodent control in orchards that are subject to consistently
high levels of infestation and damage. The cost of using
endrin is lower and its performance as measured by apple
production is higher compared with other methods of control.
In the Benefit Analysis it was estimated that yield losses
if endrin were unavailable would be of a magnitude suffi-
cient to alter apple prices. In such a situation, the
impacts extend beyond users of endrin. Other affected groups
include non-users, marketing firms and consumers. Because
of the differential effect of changes in price, supply and
total consumer income spent on apple products, some affected
groups gain while the others lose. The losers include the
users of endrin who are faced with higher costs and
decreased production and consumers who pay higher unit
prices for a smaller total crop. To evaluate redistributional
effects of losses and gains between users and non-users
budgeting techniques and partial economic equilibrium models
were used. The results of this analysis are as follows:
Range in loss to endrin users, per acre
per year - $34-$69.
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Range in loss to all users, total
per year - $2.6 - $5.3 million.
Range in gain to non-users, per acre
per year - $16 - $31.
Range in gain to non-users per year,
total - $7.2 - $14.3 million
National reduction in apple production without
endrin was established to be between 1/2 to 1 percent.
(d) Impacts of Alternative Regulatory Options
1. Option 1; Continued Registration with No
Further Restrictions
The risk from continued registration of
endrin used for apple production must take into considera-
tion the "Restricted Ose" classification. Certification of
applicators would have no anticipated effect of altering the
composition of the applicators treating orchards but the
certification process should lead to some reduction in risk
through greater care in application. Risks to fish and
wildlife would be unaffected.
The benefits of continued registration
of endrin are savings in cost and improvement in yields.
Endrin also contributes to a significantly larger apple crop
which reduces price of apple products to the consumer.
(2) Option 2: Continued Registration with
New Restrictions
Label changes that the Agency considered
for reducing risks to humans and the environment included
protective clothing, methods of application, rates of
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application, the species to be controlled, evidence of
economic infestation and distance restriction. Improved
requirements for protective clothing and respirator and the
addition of a warning statement can reduce teratogenic risks
to workers. These requirements are at pages 123-124.
The rate of application has been confused,
historically concerning the distinction between an orchard
acre and a treated acre. The Agency agrees with the opinions
of Drs. Don Hayne and Ross Byers (Hayne, 1977) that the
application rate for pine voles should be 3 pints of endrin
EC per 100 gallons with 600 gallons applied to each treated
acre. This assumes, as is the usual practice, that the
one-third of the orchard that lies between the rows of trees
is not treated. The Agency believes that if the use oŁ
endrin is necessary, it should be used at a rate efficaceous
for non-resistant pine voles.
The major use of endrin for meadow voles
occurs in the Pacific Northwest and recommendations on rates
for the State of Washington indicate that 2 pints per 100
gallons of water with 300 to 350 gallons of spray per acre
of ground treated is appropriate (Hunter and Tukey 1977).
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The State of Washington further recommends that the area
actually treated can be substantially reduced without
a loss in efficacy (Tukey 1978). While no experimental data
have been submitted to support this rate of application, the
Agency must rely on the collective experience of the users
and will require that labels for western meadow vole control
reflect the recommendations of the State of Washington.
Four basic types of equipment are in general
use for applying endrin to orchards: power hand guns,
horizontal and vertical boom sprayers, and air blast equip-
ment (speed sprayers). All of these types of equipment can
be either adjusted or adapted to produce a wide range of
droplet sizes, depending mainly on nozzle orifice and
pressure. From both the standpoint of efficacy as judged by
Drs. Byers, Hayne and Young (Barbehenn 1978) and risk reduction
.(EPA, 1978b) a coarse or very coarse spray (as judged by a
layman relying on visible droplet size) is desired. Pressure
considerations alone are thus inadequate. Therefore, label
directions dealing with equipment should state "Use a very
coarse spray with minimum pressure necessary to penetrate
ground cover. Do not apply as a fine spray. Power air blast
equipment must be modified to meet the above application
restriction. Consult with State recommendations for accept-
able methods of adapting equipment." The Agency relies on
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the opinion of Dr. Hayne (1978) in both the need
for and the successful methods of adapting speed sprayers
for orchard mouse control. In his words, the cost of adapting
speed sprayers by methods used in North Carolina is "a few
dollars worth of hardware and a half hour of time."
The established record (including Velsicol's
rebuttal, 1976; EPA, 1977b; and Byers 1977, 1978) clearly
indicates that the need for endrin in orchards of the
Eastern United States is to control the pine vole. This
subterranean species is very difficult to control, even
by laborious hand placement of baits. Users agree that the
surface-feeding meadow vole can be controlled effectively
with zinc phosphide baits. Zinc phosphide baits placed above
ground present some hazards to rabbits and pheasants but it
is generally a safer pesticide than endrin for use in
orchards.
The eastern states in general have not
requested the Agency to retain endrin on the eastern meadow
vole; western states think endrin is a necessary rodenticide.
Moreover, application rates and runoff potential are lower
in the West than in the East.
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While Velsicol's proposed label indicates,
"Apply only when infestation is present...", "infestation"
could be defined as evidence of one vole in the orchard.
On the other hand, levels of economic infestation are
difficult to define (EPA, 1977b). The Agency wishes to
discourage prophylatic use of endrin for orchard mouse
control, since such practice has little benefit and may
generate resistance. A remedy to this situation is to add
the following precautionary statement, "Unnecessary use
of this product can lead to resistance in the mouse popula-
tion and subsequent lack of efficacy." Such loss of efficacy
has been well demonstrated in large orchards in Virginia
where endrin was used for 12 years (Webb, 1967).
The requirement for full protective clothing
reduces teratogenic risks to any female applicators to a MOS
of 375 and the elimination of fine sprays renders exposure
negligible (EPA, 1978b). A 50 foot distance restriction
should include bodies of water and areas occupied by
unprotected humans. With a coarse spray, this distance
effectively eliminates risk potential from drift (EPA,
1978b) and has an inconsequential economic impact (Luttner,
1978). Additionally, to reduce the probability of run-off,
the label should indicate, "Do not apply when rainfall is
imminent."
In summary, this option can reduce risks
by protective clothing, equipment restrictions, a distance
restriction, a warning on resistance, and cancelling
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use on the eastern meadow vole—none of which have a major
economic effect. Additionally, this option increases the
benefits by warning against prophylatic use. Major risks to
fish and wildlife would remain because of the high application
rate to the terrestial habitat and because the potential for
runoff would be little affected by a distance restriction of
50 feet.
3. Option 3. Cancellation
The effect of a cancellation on risks is to
eliminate those associated with endrin and to substitute
lesser risks from zinc phosphide baits. However, the
loss in benefits of endrin use on apple production are
significant. The only federally registered alternative
pesticide, zinc phosphide, is more costly and is less effica-
cious for the pine vole. The absence of endrin
would cause significant impact to users and contribute to an
important decline in apple production.
4. Selected Options: (a) Option 2: Con-
tinued Registration With Label Restric-
tions for the Pine Vole and Western
Meadow Vole; (b) Option 3: Cancellation
for Control of the Eastern Meadow
Vole
Currently, many apple producers would not
have an effective means of rodent control without endrin and
the Agency views the continued registration of endrin as
necessary to prevent major economic impacts on many indivi-
dual users. While the Agency feels that the risks to fish
and wildlife will continue- with but minor reduction, human
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risks can be reduced greatly at little cost to the user.
The Agency believes that the continued use of endrin to
control orchard mice is an undesirable situation and encou-
rages users to increase efforts to develop viable alternatives.
Option 3 is chosen because some risks can
be reduced with no loss in benefits. In the case of the
Western meadow vole, benefits appear to be higher and risks
are lower because of the lower application rate and lower
run-off potential.
4. Sugarcane
a. General Information
Sugarcane represents a small and relatively
unimportant use of endrin. The most recent estimates (EPA
1977a) indicate that approximately 1000 pounds of endrin are
applied to 500 acres to control the sugarcane borer. Endrin
is applied foliarly at a rate 0.5 lbs. A.I. four times a
year. The 500 acres represents less than 0.2% of sugar
production in Florida. Apparently some endrin is used in
Puerto Rico but the amount is unknown. Several alternative
chemicals are available in addition to biological controls
which are encouraged, particularly in Florida, Louisiana and
Hawaii (EPA, 1977a). Endrin is also registered to control
the sugarcane beetle by treating seed pieces in furrow but
the Agency's investigation indicated that little, if any,
endrin was used for this purpose (EPA, 1977a).
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b. Relative Risks of Continued Ose
Because of similarities in application
rates and environmental conditions (especially high rainfall),
risks associated with aquatic contamination from each
application of endrin for borer control should approximate
those from use on cotton, file major chemical alternatives
are monocrotophos, carbofuran and azinphosmethyl. For
aquatic organisms, monocrotophos is judged to pose less of
an acute hazard but data on environmental transport, persis-
tence, accumulation and chronic effects are inadequate to
estimate accumulation and chronic effects on aquatic organisms.
Available data indicate that endrin is clearly more hazardous
to aquatic organisms than either carbofuran or azinphosmethyl
(Coppage, 1978b).
For terrestrial wildlife, monocrotophos has
a potential for causing a significant increase in avian
mortality in comparision with endrin but this effect could
be minimized by keeping the alternative away from cover
adjacent to cane fields. The acute toxicity of carbofuran
to birds and mammals is similar to that of endrin. Azinphos-
methyl is probably equally hazardous to mammals but less
hazardous to birds (Markley, 1978).
An assessment of potential chronic effects
on humans from the three substitutes has disclosed no
probable effects (Burnam 1978b). Thus, these compounds
appear to pose less risk than endrin.
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On balance, assuming the three alternative
pesticides are used in about equal amounts to replace endrin,
use of endrin to control sugarcane borer poses greater risks
for humans* and to the environment.
For control of the sugarcane beetle, endrin
is applied to seed pieces in the furrow. Apparently this
would involve ground application with low pressure equipment
followed by covering the material with soil. Assuming
compliance with the worker safety precautions on existing
labels, very low exposure to humans and the environment
would be anticipated.
c. Benefits of Continued Use
The Benefit Study (EPA, 1977a) included an
examination oŁ the importance of endrin in sugarcane production.
It was found that several non-RPAR insecticides are available
including azinphosmethyl, carbofuran, and monocrotophos. In
addition, biological methods for controlling the sugarcane
borer are available and are used.
It was estimated in the Benefit Study that
chemical cost per acre would be increased if endrin were
unavailable. The cost increase would average about $9.20
per acre or an increase in production cost of 2.6% on those
acres affected (about 0.2% of total acres). It was reported
that alternative pesticides provide good control of the
sugarcane borers and that no change in yield was expected.
The total economic impact was estimated at $4,600. In
summary, the impact of a cancellation of endrin on sugarcane
would be a.small cost increase (2.6%) to a small amount of
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acreage (0.2%) where endrin is used for borer control.
Because of disuse, no economic benefits are associated with
endrin for beetle control.
d. Regulatory Options
(1) Option 1: Continued Registration with No
Further Restrictions
The risks of continued use of endrin for
borer control are associated mainly with the contamination
of water by drift and runoff. Some mortality to aquatic
organisms is to be expected and consumption of highly contami-
nated fish by women of child-bearing age is a possibility that
leads to some degree (MOS=»360, Bur nam, 1978c) of teratogenic
risk. Risks from beetle control appear to be negligible.
The benefits from use of endrin on sugar-
cane are negligible. A few growers benefit from lower
production costs associated with borer control. Apparent
lack of use for beetle control implies that there are no
current benefits from that use.
(2) Option 2. Continued Registration with
New Restrictions
Improved requirements for protective cloth-
ing and respirators and the addition of a warning statement
can reduce teratogenic risks to workers. These requirements
are at pages 123-124. Improvements in equipment and applica-
tion direction indicated on pages 124-125 can help to
control drift.
Because the economic analysis indicated
a marginal value associated with the use of endrin to
control sugarcane borers and because this use was not
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defended in any response to the RPAR Notice, the Agency has
not invested resources in pursuing methods that might be
taken to reduce environmental risks from borer control.
Standard label changes for worker protection would further
reduce the negligible risk associated with potential use for
sugarcane beetle.
(3) Option 3; Cancellation
Cancellation of endrin for borer control
would result in a net reduction of risks because alternatives,
as a group, are less hazardous to humans and to the environment.
Use of endrin for beetle control does not appear to pose
a potential for unreasonable adverse effects on man or the
environment and a cancellation would achieve no perceptible
reduction in risk were endrin to be used.
The loss in benefits due to a cancellation for
borer control is minimal and affects only a few growers.
Since endrin is used on small total acreage and since there
are no yield effects expected in its absence, no adverse
impacts would accrue to the agricultural sector or to
consumers. Cancellation for beetle control might delay
availability should a need for endrin arise, since there
are no registered alternatives.
(4) Selected Options: (a) Cancel Use for
Sugarcane Borer; (b) Option 2; Continued
Registration for Use on Sugarcane Beetle
with New Restrictions
The risks to nontarget aquatic organisms
is relatively high for that acreage which is treated. Use
of alternative pesticides, as a group, would result in
reduced risk.
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The benefits from the use for sugarcane
borer are extremely small. For these reasons the Agency
considers the risks to offset the marginal benefits to a few
users and therefore proposes to cancel this use of endrin.
The expected environmental risks from the.
use on sugarcane beetle are negligible. Teratogenic risks
to applicators can be reduced to an acceptable level by use
of basic safety requirements for clothing and equipment.
While there is no evidence indicating that
endrin is used for beetle control, there is no registered
alternative. Were a need to arise for this use of endrin
benefits would materialize and, since benefits would then
exceed risks, there is some merit in maintaining registrations
for this use.
5. Conifer Seed Treatment
a. , General Information
When direct seeding is used as a method to
re-establish conifer forests in the western and southeastern
U.S., destruction of the seed by rodents and birds may
hamper the success of the operation. A coating of endrin on
the seed provides protection. The most recent estimate
indicates that 500 pounds of endrin are used for this
purpose each year (EPA, 1977a). The application rate
results in from 0.002-0.015 pounds A.I. per acre. Approxi-
mately 100,000 acres are planted with treated conifer seed
annually.
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b. Risks of Continued Use
In issuing the RPAR, the Agency did not
specifically address the issue of risk criteria for conifer
seed treatment although it indicated an awareness of several
studies conducted jointly by the Fish and Wildlife Service
and the U.S. Forest Service regarding the potential risks
associated with this use. Additionally, the Agency's 1973
review (EPA/ 1973) described instances of bird mortality
associated with conifer seed treatment as did the submission
by the USFS (DSDA, 1976). That some adverse effects from
this use are to be expected then, is clearly established.
However/ in consideration of the rather lengthy growing
cycle of forest trees and consequent infrequency of seeding
on a particular site, effects on local populations of birds
are likely to be transient. Some secondary poisoning of
raptors is possible but of relatively low probability
(Markley, 1977).
Exposure to people who treat the conifer
seed is estimated to be negligible (EPA, 1978b). No other
potential for human exposure is likely.
c. Benefits of Continued Use
Endrin is the only chemical repellent register-
ed for this use. It is used on approximately 90 percent of
direct-seeded-forest plantings. Without endrin the only
alternative is hand planting nursery-grown seedlings, which
would increase per acre costs by $12-$35. Some acres can
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not be hand -planted readily because of terrain. Total costs
were estimated to be S3 million. The impact of a cancellation
would fall entirely on the user group in the immediate future,
d. Regulatory Options
(1) Option 1: Continued Registration
with No Further Restrictions
The risk of continued use in conifer seed
treatment is expected to be at insignificant levels because
of the low frequency of use (less than or equal to once per
20-40 years), the low rate of application (0.002-0.015 lbs.
A.I. per acre), and no chance for human exposure except to
the applicator who is well trained in its use. Some bird
kills and secondary poisonings would be expected but at
insignificant levels. For these reasons the risks of endrin
so used are considered to be minimal.
Endrin contributes to the success of direct
conifer seeding. This is the most economical method of planting.
Without endrin, per acre and total costs would be increased
for the user, who must bear the brunt of the cost. -Endrin
also has an indirect benefit in that direct seeding can take
place in relatively inaccessible areas with significant
run-off potential. By contributing to the successful seeding
of such areas, endrin indirectly helps to reduce erosion.
(2) Option 2: Continued Registration
with New Restrictions
The Agency sees little that can be done
to substantially reduce the relatively low risks associated
with this use. Where feasible however, adverse effects
could be minimized by constraints on timing to avoid exposure
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to large numbers of migrant birds and to sites where benefits
are relatively high. The Agency understands that this use of
endrin by the U.S. Forest Service has been limited to sites
where hand planting is difficult and the Agency encourages a
continuation of such a policy. The label should include the
statement, "Avoid use at times when large numbers of migrant
birds are anticipated".
(3) Option 3; Cancellation
The minimal risk of endrin is eliminated.
On the other hand, no chemical pesticide will replace it;
thus these treated areas would be free of chemical pesticides.
The benefits of endrin would be eliminated.
As suggested above, these benefits are substantial to users
in relation to the minimal cost of endrin. The timely use
of endrin treated seed is a factor in reducing erosion on
deforested slopes.
(3) Option Chosen: Continued Registration
With New Restrictions
In consideration of the negligible risk
associated with the endrin use, the benefits are substantial.
Endrin helps to protect the seeds in a cost efficient manner.
The Agency judges that the benefits of this use outweigh the
risk, and that this use should be retained with label warnings
to minimize exposure to large numbers of birds.
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6. Watermelon Seed Treatment (Florida Registrations)
a. General Information
Endrin is used as a prophylatic treatment
for protecting watermelon seeds against deer mice and
cotton rats in Florida. No defense of this use was provided
to the Agency until May 1978 (Weaver 1978, Conner 1978
Gillespie 1978). Kits containing endrin and either thiram
or arasan as active ingredients are sold to users who treat
essentially all of the watermelon seed planted on 65,000
acres in Florida. No alternative pesticides are registered
for this use.
b. Risks of Continued Pse
Some concern was expressed by Or. James N.
Layne (Barbehenn 1978) over the potential for secondary
poisoning of burrowing owls and caracaras which may feed on
sick or dying rodents on field edges. The Agency's opinion
(Bushong 1978) is that the risk to nontarget wildlife,
either direct or indirect, is relatively minor. While this
is a prophylactic use, planted seeds offer essentially no
wildlife exposure and most rodents apparently learn to avoid
the treated seed by ingesting sublethal doses. Since
methods of treating seeds are similar to those for conifer
seeds, human exposure is probably negligible, posing no
expected teratogenic risk to certified applicators.
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c. Benefits of Continued dse
Very little information is available concern-
ing the extent of benefits of this endrin use. Most or all
of the commercial watermelon crop in Florida is said to
be treated (Barbehenn 1978). The amount of crop damage
averted by this prophylactic use is unknown. To the extent
that crop loss is avoided/ endrin would provide a positive
benefit to the user. Florida grown watermelons are the first
melons to reach the fresh produce market. As such, these
growers benefit by selling their product at the period of peak
price. As the season advances, additional watermelons
enter the market from other producing areas and prices
decline. One explanation for the use of endrin by Florida
growers is that they want the maximum protection of their
crop to benefit from that period of high price. In summary,
the economic importance is unknown; to the extent that it
exists it would appear to be a benefit to the Florida producer
group. To the extent that uncontrolled rodent damage might
substantially decrease production, the consumer may benefit
from lower prices.
d. Regulatory Options
(1) Option 1: Continued Registration
with No Further Restrictions
The risks of continued use for watermelon
seed treatment appear to be minimal. Minimal risk to humans
is expected and the potential risk to raptors from secondary
poisoning is viewed as low.
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The benefits of continued use are unknown.
The wide spread use in Florida suggests that this could be
an important use. The beneficiaries are primarily the user
group although consumers might gain from increased produc-
tion and lower prices of watermelons.
(2) Option 2; Continued Registration
with New Restrictions-^
Since this is a prophylactic use, the
Agency considered possible procedures to reduce unnecessary
usage. Restricting treatment to edges of fields might
be adequate for protection against cotton rats (Sigmodon
hispidus) but deer mice (Peromyscus polionotus) may live in
the field centers, thus, such a restriction would not be
viable. Since the only perceived potential risk is from
/¦
secondary poisoning, the absence of target species would
eliminate that risk. Label precautions for certified
applicators are considered to be adequate.
(3) Option 3; Cancellation
The minimal risk from endrin is eliminated.
Significant benefits to Florida watermelon growers would
be lost.
(4) Option Chosen: Option 1 - Continued
Registration witn No Further
Restrictions
The risks of endrin in this use appear to
be minimal and thus at acceptable levels. The benefits are
judged to be greater than the small degree,of risk and
endrin should be maintained for this use.
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7. Vegetable and Melon Seed Treatment (California)
a. General Information
This minor use was defended by the registrant
(Scott 1976) and one user (Iverson 1976). Endrin is used
prophylactically on several kinds of vegetable seeds in
California to protect the sprouting seeds from birds. The
actual annual poundage of endrin used is confidential, but
it is of the same order of magnitude as that used for
conifer and watermelon seed treatments. The application rate
is about 3 grams per acre.
b. Risks of Continued Dse
The registrant affirmed that the function
of the treatment was to act as a repellent. Label directions
caution against exposing seed on the soil surface and also
direct users to clean up any spills. Adverse effects on
wildlife have not been reported to the Agency and the Agency
has no basis to expect that such unreasonable adverse
effects will occur from this use of endrin (Bushong, 1978).-
Label precautions appear adequate to protect.certified
applicators.
c. Benefits of Continued Use
The only information regarding the economic
importance of the use is provided by the registrant and a
user group. They report that the use of endrin is important
to protect seeds but supporting data are lacking (Ludvik,
1978e).
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d. Regulatory Options
(1) Option 1: Continued Registration
with No Further Restrictions
No unreasonable adverse effects are antici-
pated from the continued registration of endrin to treat
vegetable seeds in California. There are no registered
substitutes. The benefits of this use have not been quanti-
fied but presumably justify the cost of treatment.
(2) Option 2. Continued Registration
With New Restrictions
Label changes that would reduce risks
associated with this use of endrin are not apparent.
(3) Option 3: Cancellation
Cancellation of this use would eliminate
risks from endrin that are judged to be negligible. Benefits
claimed by users would also be eliminated. Since no alternative
pesticide is registered, some economic loss to the users
could occur.
(4) Option Selected; Option 1
As with watermelon and conifer seed treatments,
these uses poses a minimal yet acceptable level of hazard.
Although no actual estimates of economic importance are
available, it is judged that the benefits offset the risk
and the Agency proposes continued registration of this
use.
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8. Alfalfa and Clover Seed Crops (Colorado)
a. General Information
While endrin is registered to control a wide
variety of insect pests on alfalfa and clover seed crops in
Colorado, it is not recommended and little or none is believed to
used (Ludvik, 1978c and d).
b. Comparative Risks of Continued Registration
The apparent low level or lack of present
use must be put in the perspective of its potential application
relative to current alternatives. Recommended alternatives,
each of which is registered for some, but not all of the
insects on the endrin label, include toxaphene, dimethoate
and carbofuran. Considering risks to aquatic organisms, the
four compounds have been ranked from least to most hazardous
as follows: carbofuran, dimethoate, and toxaphene equal to
endrin. For wildlife, the relative acute risk is: dimethoate,
toxaphene equal to endrin> and carbofuran (Bushong, 1978b).
Human risks from this use of endrin appear
to be confined essentially to female applicators but this
teratogenic risk potential has not been assessed and is
assumed to be similar to that for wheat. Toxaphene and
dimethoate are both RPAR compounds; the concerns with
dimethoate include oncogenicity, mutagenicity, and feto-
toxicity. Carbofuran is not known to pose chronic risks
(Burnam 1978a).
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c. Benefits of Continued Registration
Since it appears that little or no endrin is
currently used to protect alfalfa and clover seed crops,
benefits are essentially nil.
d. Options Considered
(1) Option 1: Continued Registration
with No Further Restrictions
Apparent lack of present usage indicates
that no risks from endrin are now present. If endrin were
to be used, it is not clear at' this time that its risks to
man and the environment would differ substantially from, some
of the recommended alternatives. The benefits from use of
endrin presumably would be similar to those of the alterna-
tives although lack of use suggests that the benefits of
endrin may be lower.
(2) Option 2: Continued Registration
with New Restrictions :
Were registration to continue, general
improvements in safety requirements would reduce risks but
no changes specific to this use have been considered by the
Agency. The current label prohibits use of the treated
crop for feed.
(3) Option 3: Cancellation
Since endrin is not now in use, cancellation
would eliminate a potential rather than an active risk.
Alternatives that pose some risk to man and the environment
!
would continue to be used. The present picture of benefits
would remain unchanged.
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(4) Option Selected: Continued Registration
with New Restrictions
The Agency can not now conclude that the
overall risks of endrin for use on alfalfa and clover seed
crops would exceed any of the presently recommended alterna-
tives. To the extent that endrin may be used either currently
or in the future, the Agency can not conclude that the
benefits of endrin would be any less than those of the
alternatives. The Agency concludes that the registered use
of enrin should be retained with appropriate label modifications.
9. Ornamentals
a. General Information
Several federal and state registrations
include use of endrin on ornamentals to control cyclamen
mites and spittle bugs. One label (1202-75) includes
thrips, cutworms, armyworms and corn earworm on flowers
(asters, daisies, gladiolus, mums, iris, stock). The
Agency's investigation (Ludvik, 1978a and h) indicated that
endrin was neither recommended nor used by commercial
nurseries and endrin is not now available to non-certified
applicators.
b. Relative Risks of Continued Registration
Assuming endrin were to be used under current
label restrictions and classification, the Agency perceives
little potential for unreasonable adverse effects on the
environment (Bushong, 1978). The Agency's exposure analysis
estimated that the exposure from the use of endrin on orna-
mentals was 3 mg/hr dermal and 0.01 mg/hr inhalation. This
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results in a dose of 0.005 mg/kg/hr. It would require an
extremely large operation to require as much as two hours
for treatment, thus, exposure from use on ornamentals should
not exceed 0.01 mg/kg, providing a MOS of 150. The use of
protective clothing would raise the MOS to 750. Exposure to
workers who harvest plants treated with endrin can not be
estimated from the information which is available.
The major alternatives for cyclamen mites
are endosulfan and dicofol (Ludvik, 1978h). Dicofol is a
suspect carcinogen (Burnam, 1978a). Alternatives for spittle-
bugs are chlorpyrifos and resmethrin (non-RPAR), lindane and
rotenone (RPAR compounds). Registered alternatives for
other insects vary with the site and include additional RPAR
compounds (carbaryl, trichlorfon, toxaphene) and additional
non-RPAR compounds (acephate, azinphosmethyl, chlorpyrifos,
disulfoton, malathion, oxydemeton-methyl, and sulfur)
(Thomas 1978).
c. Benefits of Continued Registration
In view of the reported absence of use and
availability of numerous alternatives, the Agency has no
basis for concluding that benefits from this registered
use are either present or might develop.
d. Options Considered
(1) Option 1: Continued Registration
with No Further Restrictions
With classification for restricted use, the
Agency perceives little potential for unreasonable adverse
environmental effects from this use of endrin. Some terato-
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genie risks are possible especially since current labels do
not preclude reentry by unprotected workers and no pre-
harvest interval has been established. Lack of use indi-
cates that no current benefits are associated with the
registration and any predictions concerning potential future
benefits would be speculative.
(2) Option 2: Continued Registration with
New Restrictions
Teratogenic risks can be reduced greatly for
applicators by general safety precautions and a label warning.
Since women are commonly employed in nurseries, it is essential
that a re-entry period and a pre-harvest interval be established.
The label should specify/ "Not for use in greenhouses." These
restrictions should have little economic impact.
(3) Option 3: Cancellation
Cancellation would eliminate a low potential
for environmental risk and an unknown level of teratogenic
risk from this use of endrin. In the absence of current
use and the availability of preferred alternatives, there
would be no economic impact.
(4) Selected Option: Cancellation
In the absence of established re-entry and
pre-harvest intervals, teratogenic risks must be presumed to
be present. No economic impact would result from cancellation.
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10. Tree Paint (Texas)
a. General Information
A formulation containing 1.0% endrin plus
captan and copper is mixed with water for use as a 0.33%
endrin dilution. This material is applied to the trunks of
young citrus trees by spray or brush to control ants,
termites and rodents (Ludvik, 1978b). It may also be applied
to hardwoods such as hackberry and ash to control borers.
The amount of endrin employed for this use is confidential
but the use can be characterized as very minor.
b. Risks of Continued Use
Use by certified applicators according to
label directions poses no perceptible hazard to the environ-
ment (Bushong, 1978) and negligible exposure to certified
applicators who follow current label precaution would be
expected. There are no registered alternatives for treating
citrus. The alternative for borers is an RPAR compound —
lindane.
c. Benefits of Continued Use
The registrant (Klement, 1976) alleged that
the product provided ant and rodent control to the citrus
grower when used as a banking compound and was thus important.
d. Impacts of Alternatives Regulatory Options
(1) Option 1: Continued Registration
with No Further Restrictions
Negligible risks are associated with some
probable local benefits.
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(2) Option 2; Continued Registration with
New Restrictions
Improvement of general safety precautions
and a teratogenic warning for applicators should further
reduce potential teratogenic risks with no effect on benefits.
(3) Option 3: Cancellation
Cancellation would eliminate local benefits
from this use and the negligible risks associated therewith.
(4) Selected Option: Continued Registration
With New Restrictions
The local benefits from the minor use
appear to outweigh the negligible risks.
11. Perch Treatments for Nuisance Birds
a. General Information
Two endrin products are registered to
control pigeons, starlings and sparrows that roost in
commercial areas: Rid-A-Bird Perch Solution and Sorbikil
Bird Pesticide (Texas). These two products have much
in common but have significant differences.
Rid-A-Bird is a 9.6% endrin solution used in
conjunction with artificial perches placed around agricultural
premises (indoor and rooftops), bridges, commercial, industrial
and public premises (indoor, outdoor and rooftops), domestic
dwellings (outdoor, rooftops), loading docks and pipe yards
where nuisance birds may roost or breed. The tubular metal
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perches contain a wick, the edge of which protrudes along
the length of the perch surface. The perches are filled
with about 2 ounces of the endrin formulation through a
small hole by use of a plastic squeeze bottle. Birds
landing on the perch absorb endrin through the feet from the
saturated wick and may be killed. Use is restricted to
professional pest control operators (PCO's). Annual produc-
tion is about 3000 pounds of endrin (Barbehenn 1978).
Sorbikil contains 3.5% endrin and 2.5%
paradichlorobenzene to act as a repellent. Its use was
not defended in response to the RPAR notice. It is used "For
control of pigeons, sparrows and starlings/ only" " on
roosting areas of commercial buildings. Product not to be
used around food processing plants, restaurants, or residence
buildings. Products [sic] to be used on perches only...."
"Used by Licensed PCO only. Limited to buildings only where
pest birds may become a health hazard." Annual usage is
unknown.
The only registered substitute for this
use of endrin is fenthion, a product registered by Rid-A-
Bird and designed for use in the same perches. Fenthion is
judged to be less efficacious than endrin, especially
under cold conditions. The registrant reported that the
amount of this product currently in use for bird control is
only a small fraction of the endrin so used (Barbehenn, 1978).
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b. Risks of Continued Use
(1) Human Risk
The Rid-A-Bird product is confined by the
wicks in the tubular perches, each of which bears a conspi-
cuous warning label. Human exposure is likely only by
accidental spillage. For the Sorbikil product/ "perches" are
undefined and the Agency was unable to contact by phone
either the registrant or potential users of the product to
clarify the use practices. The wording of the label permits
the product to be applied directly to ledges, girders or
other structures on which birds may perch around buildings
and the Agency's risk evaluation assumes such practices to
be in effect. The label gives no directions as to the
application rate. Use of this product according to label
directions can lead to gross contamination of target species
which would pose an acute hazard to people handling dead and
dying birds. In addition, there is no provision for the protec-
tion of persons who may be involved in building maintenance
and thus exposed to open puddles of endrin. The potential
risks to humans from use of this product are relatively
high in comparison to those from Rid-A-Bird.
(2) Risk to Non-Target Organisms
Cats and dogs that eat birds killed by
endrin may die from secondary poisoning and both registered
products direct the user to collect and bury dead birds. In
general, PCO's that use endrin are aware of this risk and
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Dr. W. B. Jackson advised the Agency that provision for
collecting dead birds is often specified in the contract
between the PCO and his customer (Barbehenn 1978). For birds
that are found by a pet before they have been found by a
responsible human, it is expected that those killed by the
Sorbikil product may be more heavily contaminated externally
and thus more hazardous than those killed by the Rid-A-Bird
product. Limited data (Nichols, 1977) suggest that while
fenthion is much less toxic than endrin for laboratory
rats, it may be somewhat more toxic than endrin to the
Kestrel.
While the theoretical potential for secondary
poisoning of raptors has been demonstrated, the Agency's
opinion (Markley, 1977) was that circumstances leading to
such results are generally unlikely. However, subsequent to
that opinion, the Agency learned that one of the peregrine
falcons released in an attempt to reestablish that endangered
species in the Eastern United States had established a roost
in the city of Baltimore. The Agency's position is that
peregrines that adapt to man-made cliffs should be rigorously
protected from potential exposure to endrin. A direct hazard
to barn owls is present (Bushong, 1978), where the use of
endrin for controlling nuisance birds is not confined to
specially designed perches.
c. Benefits of Continued Registration
While target birds present some theoretical
potential for transmitting various diseases to human and
livestock (Bosch, 1976) and use of the Sorbikil product is
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restricted by the label to such situations, the health
benefits from use of these products can not be determined.
Most usage is to alleviate the esthetic nuisance provided by
unsightly excrement. The benefits from the use of endrin to
control nuisance birds can best be measured by the extent to
which the public is willing to pay for the services of PCO's
to achieve such control. The Agency has no basis for
comparing the benefits of the Rid-A-Bird and Sorbikil
products.
d. Impacts of Alternative Regulatory Option
(1) Option 1: Continued Registration
This option retains the current benefits
from the use of endrin to control nuisance birds around
buildings and other structures but does nothing to reduce
associated risks. Since this use is already restricted to
PCO's, classification for restricted use will have little
impact on risk reduction.
(2) Option 2: Label Modifications
Secondary hazards to non-target species can
generally be reduced by a more rigorous effort to collect
and dispose of dead birds. Existing labels are vague about
this responsibility and this situation should be clarified by
the registrant in consultation with the Registration Division.
Label must carry the warning, "Do not use in areas identified
as roosting or nesting sites for peregrine falcons". The
Agency recommends that the FWS inform the registrant
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of areas to be protected as they become known and that the
registrant immediately inform all users in the region
surrounding the area. While the FWS may set standards
it deems appropriate, Dr. Tom Cade (Barbehenn, 1978) agrees
that a restrictive distance of at least one mile from
established roosts and two miles from active nests would
substantially reduce potentials for secondary poisoning.
The Agency perceives no realistic way to
bring risks associated with the unconfined use of endrin on
"perches" down to the level of risk provided by use in
confined, artificial perches.
(3) Option 3: Cancellation
Cancellation of endrin would eliminate both the
relatively low risks and the relatively high benefits
associated with the control of nuisance birds. The replace-
ment for endrin would be fenthion, a compound posing similar
but lower risks from secondary poisoning but having lower
efficacy. However, fenthion has no known chronic risks from
acute exposure to humans. On balance, cancelling endrin
would substantially reduce benefits with some further reduc-
tion in the low level of existing risks to humans and
nontarget organisms.
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(4) Options Chosen
(a) Reregister Rid-A-Bird with Label
Changes. The relatively low risks of present use can be
further reduced by label changes without affecting the
benefits of current use.
(b) Deny Registration for Sorbikil. The high
risks relative to the Rid-A-Bird product can not be substanti-
ally reduced by any label changes known to the Agency.
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VII. List of References
Akesson, Norman B., Chairman, The Technical Advisory
Committee on Label Restrictions for Endrin-Methyl
Parathion 1.6 EC and Endrin 1.6 ECr Report from the
committee's meeting in Denver, Colorado, on December
8-9, 1977.
Akesson, Norman B., Agricultural Engineering Department,
University of California, Davis, California, August 25,
1978. Defining of Water Bodies and Streams for Endrin
Use and Limitations. Letter to Lawrence Ebner, Sellers,
Conner & Cuneo, Attorneys & Counselors, Washington, D.C.
(Sellers et al.).
Albert, Roy E., M.D., Chairman, Carcinogen Assessment
Group (CAG), June 25, 1976. Analysis of Data for
Oncogenicity of Endrin. Memorandum to Ronald E. Dreer,
Office of Special Pesticide Review (OSPR), Environmental
Protection Agency (EPA).
Albert, Roy E., M.D., Chairman, CAG, March 23, 1977.
Responses to the Endrin RPAR. CAG, EPA (Unpublished).
Albert, Roy E., M.D., Chairman, CAG, June 20, 1978.
CAG Risk Assessment for Endrin. CAG, EPA.
Argyle, R.L., G.C. Williams, and H.K. Dupree, 1973.
Endrin Uptake and Release by Fingerling Channel Catfish.
Journal of Fisheries Research Board of Canada. 30:1743-
1744.
-------
Bailey, George H. and David S. Brown, Chemists, EPA,
Environmental Research Lab, Athens, GA, July 25, 1975.
Documentation and Interpretation of Results of Simulating
Endrin Runoff with the Pesticide Transport Runoff Model.
Memorandum to Dr. John Buckley, Acting Director, Office of
Special Projects, Office of Research and Development,
EPA.
Barbehenn, Kyle, Special Pesticide Review Division
(SPRD), EPA, June 11, 1976a. Verified Statement on
Heptachlor/Chlordane Cancellation Proceedings.
Barbehenn, Kyle, SPRD, EPA, June 24, 1976b. Wildlife
Acute Hazard Calculations for Endrin. Memorandum to
the File.
Barbehenn, Kyle R., SPRD, EPA, February 17, 1977a.
Endrin RPAR. Letter to Dr. E.L. Hobson, Shell Chemical
Company.
Barbehenn, Kyle, SPRD, EPA, March 24, 1977b. Letter to
William L. Reichel, Patuxent Wildlife Research Center,
Fish and Wildlife Service, Laurel, MD.
Barbehenn, Kyle R., SPRD, EPA, August 15, 1977c.
Request for Assistance: Teratogenicity of Endrin.
Memorandum to John Knelson, Environmental Research
Center, Health Effects Research Laboratory, EPA,
Research Triangle Park, NC.
-------
Barbehenn, Kyle, SPRD, EPA, April 27, 1978a. Endrin.
Memorandum to the File (Confidential).
Barbehenn, Kyle, SPRD, EPA, May 10, 1978b. Watermelon
Seed Treatment. Memorandum to the File.
Barbehenn, Kyle, SPRD, EPA, May 25, 1978c. Endrin:
Watermelon Seed Treatment. Memorandum to the File.
Barbehenn, Kyle, SPRD, EPA, May 31, 1978d. Endrin:
Rid-A-Bird Substitute. Memorandum to the File.
Barbehenn, Kyle, SPRD, EPA, Augut 10, 1978e. Rid-A-
Bird Substitute and Safety Memorandum to the File.
Barbehenn, Kyle, SPRD, EPA, October 3, 1978f. Endrin
Risk to Peregrine Falcons. Memorandum to the File.
Barbehenn, Kyle, SPRD, EPA, October 11, 1978g. Appli-
cation Methods for Endrin on Pine Voles. Memorandum to
the File.
Barbehenn, Kyle, SPRD, EPA, October 11, 1978h. Females
Involved with Aerial Application. Memorandum to the
File.
Bedford, Colin T., David H. Hutson, and Ian L. Natoff,
1975. The Acute Toxicity of Endrin and Its Metabolites
to Rats. Toxicology and Applied Pharmacology 33:115-121.
-------
Bosch, Robert D., Rid-A-Bird, Inc., August 3, 1976. Iden-
tification Notation: OPP-30000/4 Endrin, Rebuttal Cover
Letter to Federal Register Section, Attn.: Edwin Johnson,
EPA.
Brooks, Leroy H., Extension Entomologist, Kansas State
University, Manhattan, KS, November 4, 1976. Appendix
#17 to Velsicol Chemical Corporation's Response to Notice
of RPAR and Continued Registration of Pesticide Products
Containing Endrin.
Burnam, William L., Hazard Evaluation Division (HED), EPA,
March 29, 1977. Rid-A-Bird Dermal Toxicity. Memorandum to
Dr. Kyle Barbehenn, SPRD, EPA.
Burnam, William L., HED, EPA, 1978a. Summary of Toxicity
Profiles for Endrin. Criteria and Evaluation Division
(CED), Office of Pesticide Programs, (OPP), EPA (Unpub-
lished) .
Burnam, William L., HED, EPA, May 24, 1978b. Endrin
Teratology. Memorandum to Acting Director, CED, Office of
Pesticide Programs OPP, EPA.
Burnam, William L., HED, EPA, August 9, 1978c. Endrin
Evaluation. Memorandum to Kyle Barbehenn, SPRD, EPA.
-------
Burnam, William L., HED, EPA, September 20, 1978d.
Endrin Evaluation. Memorandum to Kyle Barbehenn, SPRD,
EPA.
Burnam, William L., HED, EPA, September 27, 1978e.
Endrin Toxicity. Memorandum to Kyle Barbehenn, SPRD,
EPA.
Bushong, Clayton, HED, EPA, June 28, 1978a. Requested
"Opinions on Endrin" Letter with Four Separate Risk Analyses
Attached to Kyle R. Barbehenn, SPRD, EPA.
Bushong, Clayton, HED, EPA, August 3, 1978b. Relative Fish
and Wildlife Risk of Endrin to Alternatives.
Butler, William M., BED, EPA, March 10, 1977. Evaluation
of Responses to Endrin. Memorandum to Mr. Ronald E. Dreer,
Director, OSPR, EPA.
Byers, Ross E., Editor, March 10-11, 1977. Proceedings of
the First Eastern Pine and Meadow Vole Symposium, Winchester,
Virginia.
Byers, Ross E., Editor, February 23-24, 1978. Proceedings
of the Second Eastern Pine and Meadow Vole Symposium,
Beltsville, Maryland.
Byers, Ross E., September 9, 1976. Response to Federal
Register Notice, vol. 41, No 145, pp. 31316-31319, July
27, 1976, Identification No. OPP-30000/4. Letter to
Federal Register Section.
-------
Calo, Charles J.f Manager of Toxicology, Velsicol Chemical
Corporation, November 1, 1976. Appendix #16 to Veliscol
Chemical Corporation's Response to Notice of rpar and
Continued Registration of Pesticide Products Containing
Endrin, dated November 4, 1976.
Calo, Charles J., Manager of Toxicology, Velsicol Chemical
Corporation, November 4, 1976. Letter to Edwin L. Johnson,
Deputy Assistant Administrator (DAA), EPA.
Chernoff, Neil; Robert J. Kavlock, and L. Earl Gray,
August 25, 1978. Endrin-Induced Perinatal Toxicity Studies
in the Hamster with a Review of the Pertinent Literature.
Health Effects Research Laboratory, Experimental Biology
Division, EPA. Research Triangle Park, North Carolina
(Unpublished).
Conner, Doyle; Commissioner, Florida Department of Agricul-
ture and Consumer Services, May 3, 1978. Letter to Dr Kyle
Barbehenn, SPRD, EPA.
Coppage, David, HED, EPA, 1978a. Revised Analysis of
Rebuttal - Endrin. Part I.
Coppage, David L., June 16, 1978b. Aquatic Risk Analysis
Based on Data Provided: Endrin Use on Sugarcane in Florida
vs. Alternatives Azodrin, Carbofuran and Guthion. EPA
(Unpublished).
-------
Coppock, Stanley, Extension Entomologist, Cooperative
Extension Service, Oklahoma State University, Stillwater,
Oklahoma, December 29, 1976. RPAR of Endrin. Letter
to Edwin L. Johnson, OPP, EPA, with Attached Copy of
Response from Edwin L. Johnson, dated March 11, 1976.
Dreer, Ronald E., OSPR, EPA, September 8, 1976. Letter
to Dr. E.L. Hobson, Shell Chemical Company.
Dreer, Ronald E., OSPR, EPA, October 17, 1977. Request
for Formal Consultation. Letter to John Spinks, Director,
Office of Endangered Species, U.S. Department of Interior.
Edwards, J. Gordon, November 9, 1976. Statement Concerning
Endrin's Effects on Fish and wildlife with cover letter
addressed to Federal Register Section, EPA.
Ebner, Lawrence S., Sellers et al., November 11, 1977a.
Endrin. Letter to Mitchell Bernstein, Esq., Office of
General Counsel (OGC), EPA.
Ebner, Lawrence S., Sellers, et al., December 19, 1977b.
Re: Endrin RPAR Letter to Mitchell Bernstein, Esq., OGC,
EPA.
Ebner, Lawrence S., Sellers, et al., January 16, 1978a.
Re: Endrin/RPAR. Letter with enclosure to Mitchell
Bernstein, Esq., OGC, EPA.
-------
Ebner, Lawrence S., Sellers, et al. January 30, 1978b.
Letter with enclosures to Mitchell Bernstein, Esq., OGC,
EPA.
Ebner Lawrence S., Sellers, et al., February 9, 1978c.
Re: Endrin/RPAR. Letter (Confidential) to Mitchell
Bernstein, Esq., OGC, EPA.
Ebner, Lawrence S., Sellers, et al., July 20, 1978d.
Letter with enclosure to Mitchell Bernstein, Esq., OGC,
EPA.
Ebner, Lawrence, S., Sellers, et al., August 31, 1978e.
Letter to Mitchell Bernstein, Esq., OGC, EPA.
Ebner, Lawrence, S., Sellers, et al., August 31, 1978Ł.
Letter to Kyle Barbehenn, SPRD, EPA.
Engler, Reto, and Joe Cunmings, HED, EPA, 1978. Evaluation
oŁ Proposed Use of Endrin in Emergency Grasshopper Control
Program, EPA (Unpublished).
Environmental Protection Agency, Pesticide Registration
Notice 71-3.
Environmental Protection Agency, November 1973. Aspects
of Pesticidal Use of Endrin on Man and the Environment.
CED, OPP, EPA (Unpublished).
-------
Environmental Protection Agency, July 27, 1976. Endrin:
Rebuttable Presumption Against Registration. Federal
Register, Part III. 41(145):31316-31319.
Environmental Protection Agency, 1977a. Preliminary Benefit
Analysis of Endrin. Economic Analysis Branch, (EAB), CEO,
OPP, Washington, O.C.
Environmental Protection Agency, May 19, 1977b. Public
Hearing on Endrin. New Paltz, New York.
Environmental Protection Agency, Region VII, May 26, 1977c.
Public Hearing on Endrin, Kansas City, Missouri.
Environmental Protection Agency, Chemistry Branch, CED, OPP,
June 28, 1978b. Endrin Exposure Analysis (Unpublished).
Greenwalt, Lynn A., Director, Fish and Wildlife Service,
U.S. Department of the Interior, June 8, 1978. Letter to
Douglas M. Costle, Administrator, EPA.
Gillespie, Janice M., Pesticide Coordinator, Florida Co-
operative Extension Service, May 4, 1978. Letter with
attachments to Dr. Kyle Barbehenn, SPRD, EPA.
Hayne, Don W., Institute of Statistics, North Carolina State
University, Raleigh, NC, December 12, 1977. Letter to
Lawrence S. Ebner, Sellers et al.
-------
Hayne, Don W., Institute of Statistics, North Carolina State
University, March 1, 1978. Memorandum to Kyle Barbehenn,
SPRD, EPA.
Hobson, E.L., Shell Chemical Company, December 14, 1976.
Letter to Dr. Kyle Barbehenn, SPRD, EPA, with'attachment:
"A Brief Guide to the Metabolism of Endrin and Analysis of
Metabolism Products" by Michael K. Baldwin.
Hobson, E.L., Shell Chemical Company, July 1, 1977
(received). Re: Endrin RPAR. Letter to Kyle Barbehenn,
SPRD, EPA.
Holtorf, Roger C., Benefit and Field Studies Division
(BFSD), EPA, July 20, 1978. Endrin-Cotton Analysis.
Memorandum to Kyle Barbehenn, - SPRD, EPA.
Hunter, Raymond E. and Ronald B. Tukey, revised September,
1977. Mouse Control in Washington Orchards. Cooperative
Extension Service, Washington State University, Pullman,
Washington.
Hutson, D.H., M.K. Baldwin, and E.C. Hoadley, 1975. Detoxi-
cation and Bioactivation of Endrin in the Rat. Xenobotica,
5(11):697:714.
International Research and Development Corporation,
December 16, 1977. Teratology Study in Rats and Teratology
Study in Hamsters. Reports Done for Velsicol Chemical
-------
Corporation. Cover Letter by Thomas R. Loy, Manager, Regu-
latory Activities, Velsicol Chemical Corporation.
Iverson, R.M., Production Manager, Let-Us-Pak, August 12,
1976. Letter to Federal Register Section, EPA.
Johnson, Louis R.C., Biologist, Lousiana Wildlife and
Fisheries Commission, December 13, 1976. Report on Bayou
Bartholomew Lake Fish Kill.
Klement, Will; Manager, Insecticide Department, Tide Pro-
ducts, Inc., October 8, 1976. Endrin Registration. Letter
to Federal Register Section, EPA.
Kleopfer, Robert D., Surveillance and Analysis Division,
Region VTI, EPA, August 6, 1976. Letter to Ross Harrison,
Kansas Forestry, Fish and Game Commission, Analytical
Results and two Letters Addressed to C.E. Poindexter, EPA,
Region VII, from Grace M. Clark, Animal and Plant Health
Inspection Service, USDA; and from Frederick W. Oehme,
D.V.M., Ph.D., Comparative Toxicology Laboratory, Kansas
State University, Manhattan, Kansas.
Kutz, Frederick W., August 28, 1978. Endrin Monitoring:
Grasshopper Control. Memorandum to Kyle Barbehenn.
Loy, Thomas R., Manager, Regulatory Activities, Velsicol
Chemical Corporation, April 11, 1978. Letter to Timothy A.
Gardner, Registration Division, OPP, EPA.
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Ludvik, George F., BFSD, EPA, May 26, 1978a. Patterns for
Minor Uses of Endrin - Ornamentals. Memorandum to Kyle R.
Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, May 20, 1978 b." Minor Uses of
Endrin - Tree Trunk Paint: Citrus: Texas. Memorandum to
Kyle R. Barbehenn, SPRD, EPA.
Ludvik, George P., BFSD, EPA, May 30, 1978c. Minor Uses of
Endrin - Alfalfa and Clover Seed Crops. Memorandum to Kyle
R. Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, May 30, 1978d. Minor Uses of
Endrin: Wheat and Small Grains, Grasshoppers - Montana.
Memorandum to Kyle R. Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, May 31, 1978e. Minor Uses of
Endrin: Vegetable Seed Protectant, Birds - California.
Memorandum to Kyle R. Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, June 21, 1978f. Minor Uses of
Endrin: Alternatives for Control of Grasshoppers in Wheat.
Memorandum to Kyle Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, June 21, 1978g. Minor Uses of
Endrin: Alternatives for Chinch Bug Control in Sorghum.
Memorandum to Kyle R. Barbehenn, SPRD, EPA.
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Ludvik, George F., BFSD, EPA, July 6, 1978h. Minor Uses of
Endrin: Ornamentals, Alternatives. Memorandum to Kyle
Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, July 6, 1978i. Minor Uses of
Endrin: Small Grains and Cotton - Alternatives. Memorandum
to Kyle Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, July 6, 1987j. Minor Uses of
Endrin: Alfalfa and Clover Seed Crops - Alternatives.
Memorandum to Kyle Barbehenn, SPRD, EPA.
Ludvik, George F., BFSD, EPA, July 7, 1978k. Minor Uses of
Endrin: Alternatives for Chinch Bug Control in Corn.
Memorandum to Kyle Barbehenn, SPRD, EPA.
Luttner, Mark A., BFSD, EPA, December 15, 1977. Revision of
Endrin Label. Memorandum to Kyle Barbehenn, SPRD, EPA.
Markley, Merle H., HED, EPA, December 1Q, 1976. Endrin
RPAR. Memorandum to Kyle Barbehenn, SPRD, EPA.
Markley, Merle H., HED, EPA, February 2, 1977. Endrin -
Velsicol Rebuttal to RPAR. Memorandum to Kyle Barbehenn,
SPRD, EPA.
Markley, Merle H., HED, EPA, June 16, 1978. Terrestrial
Wildlife Risk Analysis of Endrin vs. Alternatives on Sugar
Cane (Unpublished).
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McEwen, Lowell; Leader, Rocky Mountain Field Station,
Patuxent Wildlife Research Center, Fish and Wildlife Ser-
vice, August 1, 1978. Field Studies of Endrin Use on
Wheatland in Colorado with cover letter and attachments to
Mr. Kyle Barbehenn, SPRD, EPA.
Mississippi State University, 1977. Mississippi Studies
Program: Annual Report #9. Mississippi State Chemical
Laboratory under EPA Contract #NEG: 68-01-1944. Draft
Report. State College, Mississippi.
Mississippi Epidemiologic Studies Program, June 30, 1978.
Final Report Endrin Method Development, cover memorandum
from Jerome Blondell, EPA, to Kyle Barbehenn, SPRD, EPA.
August 7, 1978.
Mrak, Emil M., Chairman, Secretary's Commission on Pesti-
cides and Their Relationship to Environmental Health,
December 1969. Report of the Secretary's Commission on
Pesticides and Their Relationship to Environmental Health.
U.S. Department of Health, Education, and Welfare.
Nichols, C. Scott, Department of Physiological Sciences,
University of California, Davis, California, August 15,
1977. A Summary of the Current Research into the Develop-
ment of an Avicide for the Control of Starlings through the
use of Toxic Perches (Unpublished).
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North Carolina Department of Water and Air Resources,
November 1970 - March 1971. Report of Fish Kill Investiga-
tion in Lake Junaluska, Haywood County.
Odom, Robert F., 1976, Appendix #13 to Velsicol .Chemical
Corporation's Response to Notice of RPAR and Continued
Registration of Pesticide Products Containing Endrin.
O'Mara, G.K., SPRD, EPA, September, 1978a. Reevaluation of
Benefits Assessments of Cotton, SPRD, OPP, EPA. Washington,
D.C.
O'Mara, G.K., SPRD, EPA, August 25, 1978b. Memorandum to
the File: Conservation with James Touhey, Acting Director,
BFSD, OPP, EPA, Regarding Section 18 Compounds on Cotton.
Ottolenghi, Anna D., J.K. Haseman, and F. Suggs, 1974.
Teratogenic Effects of Aldrin, Dieldrin, and Endrin in
Hamsters and Mice. Teratology 9:11-16.
Reichel, William L., Patuxent Wildlife Research Center, Fish
and Wildlife Service, Laurel, MD, March 18, 1977. Analytical
Report for the Six Bald Eagle Carcasses Analyzed Only for
Endrin. Letter to Kyle Barbehenn, SPRD, EPA.
Roselle, Robert E., Department of Entomology, Cooperative
Extension Service, University of Nebraska, Lincoln, Nebraska,
December 23, 1977. Letter to Dr. Norman Akesson, Agricultural
Engineering Department, University of California, Davis,
California.
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Roselle, Robert E., Department of Entomology, Cooperative
Extension Service, University of Nebraska, Lincoln, Nebraska,
January 4, 1978. Letter to Dr. Norman Akesson, Agricultural
Engineering Department, University of California, Davis,
California.
Sears, Earl W., Executive Vice President, National Cotton
Council of America. Letter to Federal Register Section,
EPA, with attached letter from National Cotton Council of
America to Dr. William M. Upholt dated May 29, 1972.
Scott, D.B., Technical Director, Soil Serv, Inc. Salinas,
California, July 28, 1976. Letter to Federal Register
Section, EPA. Reference: OPP-3000014, Endrin 6973-04743.
Stewart, B.A., Coordinator, Committee of Scientists of
Agricultural Research Service, USDA, November, 1975.
Control of Water Pollution from Cropland. Volume I. A
Manual for Guideline Development. Prepared under an Inter-
agency Agreement with the Office of Research and Development,
EPA. Report No. EPA-600/2-75-026a.
Stickel, Lucille F., Director, Patuxent Wildlife Research
Center, Fish and Wildfish Service, Laurel, MD, December 22,
1976. Cover letter to Dr. Kyle Barbehenn, SPRD, EPA,
Concerning Endrin RPAR with attached Analytical Reports.
Thomas, E.D., BFSD, EPA, July 31, 1978. Endrin Alternatives.
Memorandum to Kyle Barbehenn.
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OSDA, Pesticide Registration Notice 68-6.
OSDA/State Assessment Team on Endrin, November 4, 1976.
Pesticide Impact Assessment: Endrin.
USDA, January 10-12, 1977a. 30th Annual Conference Report
on Cotton Insect Research and Control, Atlanta, Georgia.
Agricultural Research Service.
USDA, January 1977b. The Bollworm and Tobacco Budworm on
Cotton. Status of Insecticides and Other Methods of Control
for 1977. Washington, D.C.
OSDA, January 9-11, 1978. Thirty-First Annual Conference
Report on Cotton. Insect Research and Control, Dallas,
Texas (Preliminary Working Draft).
Velsicol Chemical Corporation, November 4, 1976. Response
to Notice of RPAR and Continued Registration of Pesticide
Products containing findrin (Including 28 Appendices).
Voris, Stephen S., Foster D. Snell, Inc., Consulting
Chemists & Engineers, N.Y., NY, June 20, 1963. Letter to
David B. Scott, Soil Serv, Inc., Salinas, California.
Received by EPA, Federal Register Section, August 2, 1976.
Weaver, Lynda W., Asgrow Florida Company, May 2, 1978.
Letter with attachments to Kyle R. Barbehenn, SPRD, EPA,
with enclosures.
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Webb, Ryland E. and Frank Horsfall, Jr., 1967. Endrin
Resistance in the Pine Mouse. Science 156 (3783):1762.
Willis, G.H. and R.A. Hamilton, 1973. Agricultural Chemicals
in Surface Runoff, Ground Water, and Soil: 1, Endrin.
Journal of Environmental Quality, 2(4):463-466.
Yates, W.G., N.B. Akesson, R.E. Cowden, 1974. Criteria for
Minimizing Drift Residues on Crops Downwind from Aerial
Applications. Transactions of the American Society of
Agricultural Engineers 14(4);627-632.
Young, David F., Mississippi Cooperative Extension Service,
August 30, 1976. Reply to Endrin RPAR, addressed to Federal
Register Section, EPA.
Zygadlo, Linda, BFSD, EPA, May 11, 1978a. Use of Endrin in
Kansas. Record of Communication. Dr. Leroy Brooks, Dept.
of Entomology, Kansas State University, Manhattan, Kansas.
Zygadlo, Linda, BFSD, EPA, June 1, 1978b. Endrin - Small
Grain Regulatory Option Analysis. Memorandum to Kyle
Barbehenn, SPRD, EPA.
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VI. Summary of Proposed Courses of Action
In summary, the Agency proposes to continue registra-
tion of the uses of endrin for which the benefits outweigh
the risks to humans and to the environment and for which
appropriate label changes will make the benefits outweigh
the risks. EPA will cancel the uses of endrin .for which the
risks to humans and to the environment outweigh the benefits
and where the risks cannot be adequately reduced so that
they are exceeded by the benefits.
A. Cotton
1. Cancel uses east of Interstate Route 35.
2. Continue registration for use west of Interstate
Route 35 with appropriate label changes.
B. Small Grains
1. Cancel use for the control of all pests other
than pale western cutworm, army cutworm and
grasshoppers.
2. Continue the registration of endrin for pale
western and army cutworms and grasshoppers with
appropriate label changes.
The required label changes include specifica-
tions for protective clothing and equipment for workers,
a teratogenic warning on the label, limitations on equipment to
be used and conditions associated with application, a 150 yard
distance restriction from human habitation, a 1/4 mile distance
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restriction from permanent bodies of water other than privately
owned, recreational ponds, a warning regarding private ponds
and a requirement to collect and bury any accidentally killed
fish, and to post contaminated ponds.
C. Orchard Mice
1. Cancel the use on meadow voles in the Eastern U.S.
2. Continue registration for pine voles and western
meadow voles with appropriate label changes.
The required label changes include protective
clothing for users, a teratogenic warning, restriction to
equipment capable of ground application in the form of a
very coarse spray, a restriction against application when
rainfall is imminent, a distance restriction of 50 feet
from water bodies and areas occupied by unprotected people
or livestock, a requirement to collect and bury any acci-
dentally killed fish and to post contaminated ponds, a
warning on the development of resistance from prophylactic
use, and reduced treatment rates for the western meadow
voles.
D. Sugarcane
Cancel use for the sugarcane borer.
Continue registration for the sugarcane beetle with
appropriate label changes.
E. Conifer Seed Treatment
Continue registration with appropriate label
changes and a caution on migratory birds.
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Watermelon Seed Treatment (Florida)
Continue registration.
Vegetable and Melon Seed Treatment (California)
Continue registration.
Alfalfa and Clover Seed Crops (Colorado)
Continue registration with appropriate label
changes.
Ornamentals
Cancel.
Citrus Tree Paint (Texas)
Continue registration with appropriate label
changes.
Perch Treatments for Nuisance Birds
1. Deny Registration for Sorbikil (Texas).
2. Continue registration for Rid-A-Bird with
appropriate label changes and distance restraints-
for Peregrine Falcons.
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