ETHYLENE DIBROMIDE (EDB)
POSITION DOCUMENT 4
OFFICE OF PESTICIDE PROGRAMS
U.S. ENVIRONMENTAL PROTECTION AGENCY
September 27, 1983
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EXECUTIVE SUMMARY
This Position Document (-PD')-4- presents the Agency's final determi-
nation regarding the Rebuttable Presumption Against Registration
(RPAR) of the pesticidal uses of ethylene dibromide (BOB).
The RPAR was initiated by EPA in December, 1977, based on a
National Cancer Institute (NCI) study demonstrating the potential
of EDB to induce cancer in rats and mice. The basis for the
RPAR was the presumed risk of cancer to man as a result of
pesticidal exposure to EDB. The RPAR was further supported by
additional evidence submitted to the Agency showing EDB to
be mutagenic and capable of producing adverse reproductive
effects.
In December 1980, the Agency issued a Position Document 2/3
and Notice of Preliminary Determination Concluding the RPAR
which proposed several regulatory actions to reduce the
human health risks resulting from pesticidal use of EDB.
The proposed actions were based on the Agency's risk/benefit
analysis of each registered use of EDB.
EDB is registered as a fumigant for preplant application to
soil, post-harvest commodity fumigation, spot fumigation of
grain milling machinery and several other low-volume uses.
The major pesticidal use of EDB is preplant application to
soil, which comprises about 90% of domestic use.
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This final determination regarding EDB is based on an evaluation
of the comments submitted in response to PD 2/3 by the EPA
Scientific Advisory Panel, the U.S. Department of Agriculture,
industry and the general public. In reaching a final
determination, the Agency has reevaluated the health risks
and the economic benefits of EDB for the regulatory actions
proposed in PD 2/3, and has carried out a thorough scientific
and technical review of all comments received.
The Agency has now adequately developed evidence that the
preplant soil fumigant uses of BOB are likely to result in
leaching to groundwater, and, therefore, in the contamination
of human drinking water supplies. The potential contribution
of continued soil fumigant use of EDB to the contamination
of drinking water poses unacceptable risks and results in an
imminent hazard. Consequently, the Agency has determined
that it is necessary to immediately discontinue this use of
EDB through an emergency suspension order.
The uses of EDB in spot fumigation of grain mills and for
fumigation of stored grain pose a significant dietary cancer
risk to the general public and high risks to applicators and
millworkers. The Agency has determined to cancel these uses.
The Agency is extremely concerned about the potential exposure
of the public from these uses of EDB and is gathering additional
information concerning these exposures. When this additional
information has been evaluated, the Agency will consider the
need for emergency suspension of these uses.
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The Agency has determined that the use of EDB as a quarantine
fumigant to ensure fruit fly disinfestat ion of food commodities
shipped out of quarantine areas poses substantial risks to
both occupationally exposed workers and to the general public.
Further, the Agency has concluded that the human health
risks of continued use of EDB as a quarantine fumigant exceed
its benefits and that this use must be cancelled. At the
present time the Agency recognizes that there are no chemical
alternatives for this use and that other alternative technology,
including cold storage treatment and irradiation, are not
immediately available. The effective date of this cancellation,
therefore, has been delayed until September 1, 1984 to allow
USDA/APHIS and the industry adequate time to change to alterna-
tive means of quarantine fruit fly disinfestation.
The Agency has determined that the use of EDB as a felled log
fumigant to control bark beetles poses high cancer risks to
applicators and provides little economic benefits. The
Agency, therefore, has determined that this use should be
cancelled.
For the remaining uses: subterranean and drywood termite
control, fumigation of beehive supers, vault fumigation of
stored clothing and furniture, and the USDA Japanese Beetle
Quarantine Program, the Agency has decided that the final
determination regarding these low-volume uses will remain
unchanged from the proposed action. The Agency believes
there may be some exposure to applicators as a result of
these minor uses; however no data are available which
demonstrate that these exposures are significant.
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These uses will be allowed to continue if certain use restric-
tions are implemented and additional data requirements are
fulfilled. For control of termites, the current label directions
will be reinforced and expanded by allowing use only by
certified applicators. For the other uses, protective clothing
and other low-cost measures, designed to reduce exposures to
EDB, will be required. In addition, registrants of products
with each of the low-volume uses will be required to conduct
studies to determine the levels of EDB in the air to which
applicators are exposed, the number of applicators involved
in these uses, and the amounts of EDB applied annually.
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ACKNOWLEDGEMENTS
EPA ETHYLENE DIBROMIDE TEAM
Richard Johnson, Team Leader, RD
Anne Barton, Statistician, HED
Gary Burin, Toxicologist, HED
Stuart Cohen, Chemist, HED
Charalinggayya Hiremath, Toxicologist, CAG
James Holder, Toxicologist, HED
Roger Holtorf, Economist, BUD
George Ludvik, Senior Entomologist, BUD
Robert McLaughlin, Attorney, OGC
Marcia Mulkey, OGC
Neil Pelletier, Plant Pathologist, BUD
Joseph Reinert, Chemist, HED
Amy Rispin, Chemist, HED
Esther Saito, Chemist, HED
Carol Sakai, Reproductive Biologist, REAG
Richard Schmidt, Chemist, HED
Todd Thorslund, Biostatistician, CAG
Linda Vlier, Economist, BUD
John Worthington, Chemist, HED
OTHER ACKNOWLEDGEMENTS
Arvella Farmer, Secretary, RD
Barbara Moore, Secretary, RD
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TABLE Of CONTENTS
Executive Summary
I. Introduction 1
II. Analysis of EDB 2/3 Comments on Exposure and Risks 6
A. Comments Relating to Exposure 6
1. Appl icator Exposure 7
a. Preplant Soil Fumigation 7
b. Spot Fumigation of Grain Milling Machinery 9
c. Quarantine Fumigation 11
d. Felled Log Fumigation 13
2 . Dietary Exposure 14
a. Preplant Soil Fumigation 14
b. Spot Fumigation of Milling Machinery 16
c. Quarantine Fumigation 17
3 . Other Exposure 18
B. Comments Relating to Hazard 19
1 . Oncogenicity 19
2 . Muhagenicity 27
3. Reproductive Effects 28
a. Ter Haar, 1981 28
b. Levine et al., 1981 30
c. Conclusion 32
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III. Revision and Amendments to PD 2/3, Exposure and Associated
Health Risk 33
A. Applicator Exposure 33
1. Preplant Soil Fumigation 33
2. Quarantine Fumigation 36
3. Felled Log Fumigation 43
B. Applicator Risk 44
C. Dietary Exposure from Quarantine Fumigation 47
D. Contamination of wheat By-Products from Bulk Grain
and Spot Treatments of Grain Milling Machinery by EDB 55
E. Groundwater Contamination 59
F. Dietary Cancer Risk Equation 69
G. Dietary Cancer Risk 70
H. Groundwater Contamination Cancer Risk 79
IV. Analysis of PD 2/3 Comments and Revisions Relating to Benefits.80
1. Preplant Soil Fumigation 80
2. Stored Grain Fumigation 86
a. Rates and Frequency of Application 86
b. Volume used to Fumigate Grain 87
c. Conclusions for Grain Fumigation 88
3. Spot Fumigation of Grain Milling Machinery 88
a. Efficacy of Alternatives 89
b. Frequency of Application 90
c. Usage Estimates 90
d. Treatment Costs 93
e. Conclusions on Spot Fumigation 95
4. Quarantine Fumigation of Citrus, Tropical Fruits, and
Miscellaneous vegetables 96
5. Felled Log Fumigation 100
6. Minor Uses 101
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V. Summary and Conclusions 102
References and Citations
Additions to References and Citations - Groundwater
- Economics
- Exposure
Appendix I: EDB Position Document 2/3
Appendix II: Comments Received in Response to PD 2/3
Appendix III: SAP and USDA Reviews of EDB-RPAR
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List of Tables
1. Data on EDB Air Levels During Transfer and Application 34
2. EDB Respiratory Exposure During Soil Fumigation 36
3. EDB Inhalation Exposure of Workers at Citrus Fumigation
Stations at a Citrus Warehouse 38
4. Summary Table of PD 4 Applicator Exposure Estimates Which
Have Been Modified from PD 2/3 41
5. Estimated EDB Exposure to Felled Log Applicators 43
6. Revised Cancer Risk Due to Occupational Inhalation of EDB 46
7. Residue Levels in Edible Portion of Fruit (ppm) 49
8. Dietary Burden in California 52
9. Dietary Burden Comparison: Citrus and Tropical Fruits 53
10. EDB Groundwater Contamination 60
11. Comparison of the PD 2/3 and PD 4 Dietary Burdens and
Cancer Risks 72
12. Dietary Burden - Ages Specific Estimates 75
13. Incremental Dietary Cancer Risks for One Year Additional
Exposure 78
14. Cancer Risk for EDB Groundwater Contamination 79
15. Annual Economic Impact of EDB Soil Fumigation Use
Cancellation 82
16. Summary of Final Regulatory Decisions on EDB 103
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I. Introduction
Under the Federal Insecticide, Fungicide, and Rodenticide Act,
as amended (FIFRA) (7 U.S.C. Section 136 et seq.) the Environmental
Protection Agency (EPA or the Agency) regulates pesticide
products. Section 12(a)(l)(A) of FIFRA requires that all
pesticide products, unless exempted from regulation, must be
registered before they may be sold or distributed. 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 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."
Unreasonable adverse effects on the environment are defined
in FIFRA Section 2(bb) to mean "any unreasonable risk to man
or the environment, taking into account the economic, social
and environmental costs and benefits of the use of any pesticide."
In sum, any decision to register or continue to register a
pesticide must weigh both the risks and the benefits from
the use of the pesticide.
The Rebuttable Presumption Against Registration (RPAR)
process was designed to collect and evaluate benefits and
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risk information regarding those pesticides which are suspected
of causing adverse health or environmental effects, and
facilitate regulatory decisions concerning them while allowing
interested groups to participate. The regulation governing the
RPAR process is 40 CFR 162.11.
On December 14, 1977, the Agency issued a Notice of RPAR and
the RPAR Position Document 1 on EDB in the Federal Register
(42 F.R. 63134-63161). The PD 1 explained the background and
provided supporting data for the presumption of hazard cited
in the RPAR Notice. The presumption against the registration
of EDB was based on oncogenic, mutagenic and reproductive
effects in test animals. The PD 1 provided registrants and
other interested parties the opportunity to submit rebuttal
comments.
The presumption against EDB could have been rebutted by
showing: 1) that the Agency's initial determination of hazard
was in error; or 2) by demonstrating that existing use
patterns and the resulting exposure to EDB did not induce
any significant adverse effects. (See 40 CFR 162.11 (a)(4))
Respondents were also asked to submit evidence of the social,
economic, and environmental benefits from the uses of the
pesticide. See 40 CFR 162.11 (a)(5)(iii).
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On December 10, 1980, the Agency issued "Pesticide Products
Containing Ethylene Dibromide (EDB); Preliminary Notice of
Determination Concluding the Rebuttable Presumption Against
Registration; Availability of Position Document 2/3."
45 FR: 81516-81524). In the PD 2/3, the Agency concluded that
the presumptions of oncogenicity, mutagenicity, and reproductive
effects were not rebutted. The PD 2/3 also presented the Agency's
evaluation of rebuttal comments received in responnse to the
original RPAR Notice. It provided the Agency's analysis of
the risks and benefits associated with the use of EDB and it
presented the regulatory options that were considered for
purposes of risk reduction. Finally, the PD 2/3 contained the
Agency's proposed regulatory approach to conclude the RPAR. The
PD 2/3 is summarized below and included in its entirety as
Appendix I.
Summary of PD 2/3
The Position Document (PD) 2/3 proposed several regulatory
actions to reduce the human health risks resulting from registered
pesticidal uses of ethylene dibromide (EDB). These proposed
actions were based on the Agency's determination that certain
uses of EDB resulted in unreasonable adverse effects to man.
All of the registered uses of EDB were examined in this
document. These include: preplant fumigation of soil (to
control nematodes); fumigation of stored grains (to control
insects); spot fumigation of grain milling machinery (to control
insects); post-harvest fumigation of citrus, tropical fruits,
and vegetables under USDA Animal, Plant and Health Inspection
Service (APHIS) guarantine (to control fruit flies); fumigation
418-574 0-83-2
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of felled logs to control bark beetles); fumigation of stored
beehive supers and honeycombs (to control the greater wax moth)
vault-fumigation of stored furniture and clothing (to control
various pests); treatment of plants, soil and grass sod in
accordance with the USDA/APHIS Japanese Beetle Quarantine
Program; and fumigation beneath concrete slab foundations of
buildings and porches to control subterranean termites, and
spot fumigation of their galleries to control drywood termites.
The first regulatory action the Agency proposed was to
allow registration to continue for preplant soil fumigation,
the largest volume use of EDB. However, the Agency would permit
this use only if certain restrictions were implemented and
additional data requirements were fulfilled. Specifically, the
Agency would require applicators to wear respirators and
protective clothing; reentry into a treated field would also be
prohibited for 24 hours following fumigation. The Agency would
have required soil fumigant registrants to conduct studies to
determine if this use results in groundwater contamination.
When results from these studies were available, the Agency would
reexamine the adequacy of its regulatory measures for this use.
Second, the Agency proposed to cancel the EDB registrations
for two other major uses; fumigation of stored grains and spot
fumigation of grain milling machinery. The bases for these
proposed cancellations was that the public health risks of
cancer, heritable genetic damage, and reproductive disorders
outweighed the economic benefits of these uses. The Agency
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concluded that residues of EDB contaminate the human diet as a
result of these registered uses. Applicators, persons near a
treatment site and workers who handle treated commodities are
also exposed to significant levels of EDB via inhalation and
dermal contact.
Third, the Agency proposed that on July 1, 1983, EDB regis-
trations for post-harvest fumigation of citrus, tropical fruits
and vegetables would be cancelled. The interim period would
provide time for the development and implementation of
efficacious alternatives.
Fourth, the Agency proposed to cancel the EDB registration
for fumigation of felled logs, a relatively low volume use.
The basis for this action is the Agency's determination that
the potential risks to applicators outweigh the economic bene-
fits of this use.
Finally, for the remaining uses: fumigation of beehive
supers, vault fumigation of stored clothing and furniture, and
the USDA's Japanese Beetle Quarantine Program, the Agency
proposed to allow these uses to continue only if certain use
restrictions were implemented and additional data requirements
were fulfilled. Specifically, the Agency would require
protective clothing and other low-cost measures designed to
reduce applicator exposures to EDB. In addition, the Agency
would require registrants of products with each of these uses
to conduct studies to determine the EDB air levels to which
applicators are exposed, the number of applicators involved in
these uses, and the amounts of EDB applied annually for these
uses.
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1 *• Analysis of PD 2/3 Comments on Exposure and Risk
The Agency has revised some aspects of its assessment of risks,
benefits and regulatory requirements in accordance with additional
information provided by the public, United States Department
of Agriculture (USDA), Science Advisory Panel (SAP) and other
sources. Except as discussed below and in Section III, other
aspects of the analysis presented in the PD 2/3 are unchanged.
A. Comments Relating to Exposure
The Agency has received comments relating to exposure to EDB
as follows:
Use pattern Cgmmenter
Preplant Soil Fumigation (#24) Great Lakes Chemical Corp.
(#34) Dow Chemical Co.
Spot Fumigation Grain Milling (# 2) Millers' National Federation
Machinery (#22) Ferguson Fumigants, Inc.
Fumigation of Stored Grain (#2) Millers' National Federation
Quarantine Fumigation (#23) Hawaii Papaya Industry
Assoc.
(#25 and #25A) Florida Dept. of
Citrus
Felled Log Fumigation (#15 and #15A) Colorado State
Forest Service
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1. Applicator Exposure
a. Preplant Soil Fumigation
Dow Chemical Co., has submitted new exposure studies for this
use of EDB (Skoronski, 1979, and Martin, 1980). These studies,
along with some clarifying information provided by Dow (Martin,
1982), have been evaluated by the Agency. The air levels of EDB
reported in these studies are substantially higher than those
used by the Agency for the PD 2/3 applicator exposure assessment.
The PD 4 applicator exposure assessment for this use has been
modified accordingly (see Section III).
Great Lakes Chemical Co. (Comment #24) stated that it is
unrealistic to assume that 100% of inhaled EDB is absorbed by
the lung; however, Great Lakes did not suggest or provide a
basis for choosing an alternative. Great Lakes stated that a
respiratory rate of 0.6 m^/hr would be a more appropriate
value to use than the 1.2 m^/hr value for moderate activity
used in PD 2/3, and that the NIOSH EDB Criteria Document (NIOSH,
1977) used this 0.6 m3/hr figure. The document did use the
0.6 nvVhr value, but it is not stated what level of physical
activity this breathing rate corresponds. The Agency consistently
uses a 1.2m3/hr value for males engaged in light to moderate
work (Hayes, 1975).
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Great Lakes offered "more realistic" estimates of annual and
lifetime durations of applicator exposures. The Agency considers
these estimates more reliable (Weidman, 1981) than those used
in PD 2/3 and they have been used for the modified applicator
exposure estimates in this PD 4 (see Section III A).
Great Lakes stated that requiring applicators to wear respirators
is unnecessary since even the highest lifetime exposure calculated
in PD 2/3 (Table 16, p. 48) is less than the NIOSH recommended
standard of 130 ppb (NIOSH, 1977). Great Lakes suggested that
the Agency consider as an alternative regulatory option that
respirators be required only "... when the product is exposed
to the environment during small spills, repairs, calibration,
transfers or sampling." The highest exposure in Table 16 (532.4
mg/yr for pineapple soil fumigation application) corresponds
to a lifetime exposure of about 300 mg/kg. This compares to
the NIOSH figure of 686 mg/kg which is stated to be "substantially
below that total dose known to induce adverse effects in
experimental animals." This dose level was published prior to
findings of the cancer inducing potential of EDB. The Agency
rejects the use of this exposure level in regulating a cancer
causing chemical, such as EDB. It is Agency policy that,
lacking valid scientific evidence supporting a threshold (below
which no risk of cancer exists), any exposures other than zero,
must be presumed to be attended by a risk of cancer in humans.
The Agency has determined that the risk posed to applicators,
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as well as the risk posed by contamination of ground water
aquifers (as discussed in Section III E and H of this document)
from this use of EDB, require emergency suspension of registra-
tions of this use. The revised exposure assessment for this
use is discussed in detail in Section III of this document.
b. Spot Fumigation of Grain Milling Machinery
The Miller's National Federation (MNF) (Comment #2) commented
that the Agency's calculation of applicator exposure during
the spot fumigation of milling machinery did not consider the
case in which respirators are worn properly, or take into
account the rotation of applicators . EPA, however, evaluated
this situation in the PD 2/3 (see case I, table 18, p.54 of PD
2/3). The text describing this table (p. 53 of PD 2/3, second
paragraph) contains a transcription error; this sentence should
read: "Alternatively, with proper use of the respirator and
rotation of applicators, an inhalation exposure of 4.3 - 12.5
mg/kg/yr is estimated."
MNF stated that the Agency incorrectly used an air level value
of 3.8 ppm (the limit of detection) as a persistence level
for a full 8-hour day during normal operations, even though
air sampling was discontinued when the limit of detection
was reached. The Agency agrees that this approach leads to
a bias toward higher exposure, but in the absence of more
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precise data, this approach is considered to be a prudent and
reasonable approach.
MNF stated that the exposure ranges for applicators and workers
(p. 65 in PD 2/3) overlap, and that this overlap represents
"a highly improbable situation". MNF, however, did not point
out which assumptions or calculations are incorrect or
could lead to this "improbable situation." The use of pro-
tective equipment by applicators and not millworkers, and
the significantly longer exposure of millworkers provides
explanation for this result.
MNF urged the Agency to consider requiring respirators only
during the high exposure times (opening or opening and start-up)
to reduce risk. The Agency fully considered the use of
protective equipment in this use, but concluded any realistic
assessment of the effectiveness of such a restriction would
still leave significant applicator exposure. This exposure
combined with the dietary exposure to the general public
compelled the conclusion that this use presents unreasonable
adverse effects.
Ferguson Fumigants, Inc. (Comment #22) reemphasized their
claim that applicator exposure is "nil" since an essentially
closed system is employed. No new data were provided to
support this comment, and the available information, instead,
demonstrates significant exposure potential.
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c. Quarantine Fumigation
Florida Dept. of Citrus (FDC) (Comments #25 and #25A)
challenged the data on levels of EDB used to calculate
exposure to fork-lift truck operators at port warehouses.
The Agency acknowledges that the data used were limited.
However, the Agency believes that the difference in the levels
reported is probably the result of the length of time the
fruit has been in storage in the warehouse, and continues to
believe the levels used in the PD 2/3 were appropriate.
FDC claims that the Agency based its calculations of average
inhalation exposure to warehouse workers on two exaggerated
assumptions. First, that workers were exposed for 155 days a
year. The Agency agrees with FDC that fumigation stations do
not operate 155 days per year. The Agency, however, calculated
the applicator exposure at the fumigation station in the PD
2/3 at 112 days per year (the average number of operating days
at Wahneta during the 1978-1980 seasons). Because bleed-off
from the cartons and fruit continues beyond the day of treatment,
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the Agency believes that the exposure period of 155 days during
the period from October through May is not an exaggerated
assumption for warehouse workers who handle the fruit after
treatment.
Second, FDC states that work at the citrus fumigation stations and
port warehouses can hardly be classified as "heavy activity"
because such work does not involve much exertion or heavy
physical activity. The Agency has now used a breathing rate of
1.2 m^/hr, the applicable rate for males engaged in "light
to moderate activity" in calculating exposure (see Section
III), instead of 1.8 m3/hr as used in the PD 2/3.
The Hawaii Papaya Industry Association (Comment #23) submitted
two studies of air levels of EDB in papaya fumigation plants. The
NIOSH study submitted has been reviewed, but cannot be used as
the basis for a worker exposure assessment, because of significant
deficiencies, i.e., inadeguate method of analysis, sample size,
and protocol in the design of the study (Day, 1981). The
second study submitted by the Hawaii Papaya Industry Association
(Hertlein and Hagadone, 1981) has been reviewed by the Agency
and can be used for the calculation of exposure to workers at
papaya fumigation sites. This study is the basis for the
exposure analysis presented in Section III.
The Agency has also received a summary of a monitoring study
conducted by NIOSH at Hilo, Hawaii. The values in this study
are slightly lower than those found by Hertlein and Hagadone.
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The reduction appears to have occurred because the Papaya industry
now employs charcoal filtration in refrigeration rooms and
fumigation chambers. However, these results are within an
order of magnitude of the Hertlein and Hagadone results and
would not result in a substantial change in exposure estimates.
d. Felled Log Fumigation
In PD 2/3, the Agency stated that no data were available on
applicator exposures during felled log fumigation. In response
to the PD 2/3, the Colorado State Forest Service (CSFS) (Comment
#15A) submitted two exposure studies reported in a 1973 USDA/Forest
Service Document (Undi, 1973). These studies have been accepted
and are the basis for the exposure assessment presented in
Section III.
CSFS stated that the use concentration of EDB is 4.5%, not 23%
as stated in PD 2/3. The Agency has confirmed that the typical
concentration of EDB used against the mountain pine beetle
(the main target pest of the forestry use of EDB) is a 5:1
volume/volume dilution of a 23% formulation. This corresponds
to a 4.76% weight/weight use concentration. This figure has
been used for the exposure assessment in Section III.
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2. Dietary Exposure
a. Preplant Soil Fumigation
Great Lakes Chemical Corp. (Comment #24) stated that the
analytical method in a California Department of Food and Agri-
culture (CDFA) study (Maddy et al., 1979) has a gualitative
limit of detection (the minimum concentration which produces a
signal which can be unambiguously recognized above background)
of 0.1 ppb. Great Lakes contended that this value is the proper
one to use in the dietary exposure calculations, rather than
the quantitative detection limit (the lowest signal which can
be used to reproducibly quantify the amount of chemical present)
of 1 ppb, which was used in PD 2/3. However, scientists familiar
with the CDFA method (Communications, J.C. Reinert, T. Jackson,
D. Rains) indicate that for some crops analyzed, the qualitative
limit of detection (for a 4:1 signal: noise ratio) is well
above 0.1 ppb.
Thus, the Agency believes that recalculating the dietary exposure
for preplant soil fumigation is unwarranted. This is because
choice of a proper residue level is uncertain and, furthermore,
any change would result in a change of less than an order of
magnitude in dietary exposure. As noted by Great Lakes, the
estimated dietary exposure is hypothetical, and any actual
residues of EDB in crops, would probably be at concentrations
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below this level. The Agency estimation of dietary exposure
from preplant soil fumigation should thus be considered a worst
case projection.
Very recently, CDFA reported finding detectable residues of
EDB in carrots grown in EDB-fumigated soil (personal communi-
cation, R. Johnson and K. Maddy, CDFA, September, 1983).
These results have not yet been evaluated by the Agency.
Dow Chemical Co. (Comment #34) has submitted a series of
published papers and a theoretical treatise on the fate of EDB
in soil in order to preclude the need to conduct field dissipation
and leaching studies. Dow's arguments, while well presented,
are not persuaive regarding potential contamination of ground-
water as a result of this EDB use. Indeed, recently developed
groundwater monitoring and tests of soil movement of EDB demonstrate
that continued use of EDB as a soil fumigant can be expected to
contaminate groundwater sources.
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b. Spot Fumigation of Milling Machinery
The Millers' National Federation (MNF) (Comment #2) stated that
the Agency's PD 2/3 estimate of dietary exposure was based on
incomplete and contradictory data which was derived from samples
without defined histories. MNF argued that the Agency could
not reach a conclusion regarding the origin of EDB residues
(whether they come from the spot fumigation use or bulk grain
fumigation).
Ferguson Fumigants, Inc. (Comment 122) suggests that the
dietary exposure to EDB which results from the spot machinery
use is insignificant when compared to total dietary burden.
Although the Agency agrees that it is currently unable to
calculate the precise proportion of the total dietary burden
from grain products attributable to spot fumigation, it does
have data showing that this use may contribute significantly
to this dietary burden (see discussion in III D).
The SAP expressed its great concern over the potential human
dietary exposure to EDB residues in finished bakery products
as a result of the spot fumigation of milling machinery and
stored grain fumigation, and recommended that, because of the
extremely large population potentially at risk, these uses
should be cancelled until such time as convincing evidence
exists that these uses present no unreasonable risk to consumers.
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c. Quarantine Fumigation
The Florida Department of Citrus (FDC) (Comments #25 and 25A)
stated that the fresh citrus food factor used in PD 2/3 (3.8%)
was too high. Based on information contained in a 1979 report
from the Florida Crop and Livestock Reporting Service, FDC
calculated a fresh citrus food factor of 2.2%. The Agency
agrees that the 3.8% value used in PD 2/3 was too high. The
Agency has recalculated this value for fresh citrus only
(Reinert, 1982b) and obtained a value of 2.8%. This value is
close to that proposed by FDC and has been used in the PD 4
dietary exposure assessment (see Section III).
FDC claimed that the EDB residue level in citrus used in the
PD 2/3 was too high. It was estimated from a derived residue
loss equation and used for the dietary exposure assessment.
FDC presented actual analyses of EDB residues in the edible
portion of citrus at various times after fumigation (King et
al. , 1980). The results for the edible portion of grapefruits
(avg. residue level = 0.027 ppm) and oranges (0.029 ppm) seven
days after fumigation are in good agreement with the most
recent data of Maddy (Maddy, 1981a), which have been used in
the PD 4 dietary exposure assessment (see Section III). Very
recent data submitted by USDA (USDA, September, 1983) are
discussed in Section III.
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3. Other Exposure
FDC suggested that, although the potential exposure of
populations in private residences located a short distance
from fumigation stations is low, increasing the exhaust stack
height from 10 to 30 meters could aid in reducing ground level
EDB concentrations by increasing atmospheric dispersion. The
Agency agrees that EDB exposure to the general population
should be reduced to the lowest level feasible in areas sur-
rounding citrus fumigation stations.
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19
B. Comments Relating to Hazards
1. Oncogenicity
The Millers National Federation (MNF) (Comment #2) and the
Occidental Chemical Company (Comment #28) both stated that the
route of administration in the 1977 NCI study, intubation, was
inappropriate because human exposures would be primarily by
inhalation. The Agency's Carcinogen Assessment Group (CAG)
recognizes the difficulties in determining the human inhalation
dose from a rodent intubation study. However, two inhalation
studies in rodents have since been completed (Wong et al.,
1979 and NCI, 1980)and the risk estimate for inhalation is now
based on a rat inhalation study.
The Florida Department of Citrus (FDC) (Comments #25 and #25A)
stated in their comments that results from bioassays cannot
properly be used to calculate risk estimates for humans, since
it has not been demonstrated that humans metabolize a substance
in the same way as the animal species used in the experiment.
The CAG agrees that there is no known evidence which demonstrates
that humans metabolize EDB in the same manner as do experimental
animals. However, there is also no evidence demonstrating that
humans do not metabolize EDB in the same manner as do experimental
animal. In the absence of information concerning the metabolism
of the compound in humans, it is prudent to assume that animals
are adequate models for predicting human effects. Because EDB
is a direct-acting alkylating agent and induces carcinomas in
both rats and mice, the assumption that the effects will
418-574 O - 83 - 3
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20
be the same for humans is particularly reasonable.
FDC comments that the one-hit model for assessing mutagenic
and carcinogenic potential is unsatisfactory. The FDC also
stated their opinion that the risk estimates presented in the
PD 2/3 are probably exaggerated since the one-hit, no-threshold
model is the most conservative method of calculation. FDC
suggests that the threshold concept is more valid and practical.
The dominant scientific view of carcinogenicity is that most
agents that cause cancer also cause irreversible DNA damage.
There is substantial evidence from mutagenicity studies that
the biological response characteristic of mutagenesis is
associated with a linear nonthreshold dose-response relationship,
and this model is appropriate. This is particularly true at
the lower end of the dose-response curve which represents
typical human exposures. The linear non-threshold model is
also consistent with the available epidemiological cancer
studies. (e.g., radiation-induced leukemia, breast and thyroid
cancer, and liver cancer induced by aflatoxin in the diet).
There is also some evidence from animal experiments consistent
with this model (e.g., liver tumors induced in mice by 2-ace-
tylaminofluorene).
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21
Because it has the best scientific basis of any of the
current mathematical extrapolation models, the linear
nonthreshold model has been adopted as the primary basis
for risk extrapolation to low levels of the dose-response
relationship. The risk estimates made with this model should
be regarded as conservative, representing the most plausible
upper limit for risk, i.e., the true limit is not likely to
be higher than the estimate, but it could be lower. Therefore
the Agency agrees that this model may be conservative. The
risk estimate presented in the PD 2/3, based on this procedure,
gave a plausible upper limit for risk.
The CAG has now adopted a new procedure for estimating the
cancer risks for EDB dietary exposure. The one-hit model
with "Weibull" timing, which is conceptually similar to, but
operationally more systematic than the one-hit model is now
used to estimate cancer risk for EDB, to adjust for the
short duration of the study (CAG, 1982a).
Other models, such as the multi-stage model, have also been
suggested for use in extrapolating EDB cancer risks (USDA
draft report, 1983). However, this model, as proposed by
USDA, did not take into account the extremely rapid onset of
tumor or the short duration of the study (Burin, 1983).
Furthermore, the complete model, proposed by USDA, is not
yet available for detailed scientific review. The Agency
considers the new CAG model to be the best model currently
available for determination of EDB dietary cancer risk.
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22
FDC also commented that a major fault of the NCI dietary
studies was a failure to select the proper dose of EDB. The
dose was adjusted during the study and was finally calculated
as a time-weighted average dose. This resulted in a poor
survival rate. In response, the CAG considers that the
adjustment of dose during the course of the study makes the
calculation of effective dose uncertain. However, it does not
negate the positive carcinogenic response to EDB observed in
the studies. The FDC further commented that the evidence
regarding oncogenicity falls short of establishing a connection
between cancer and EDB residues in food. They note that intubation
(introducing EDB directly into the stomach of laboratory animals)
is recognized by EPA as an inappropriate methodology for assessing
risk from foods ingested orally. They also point out that the
scientific community, in making risk assessments from food
additives, has rejected such studies for this reason.
The CAG, however, has compared tumor responses where dibromoch-
loropropane was administered via both gavage and diet, and
found no significant difference. And EDB and DBCP are:
1) structurally related halogenated aliphatic hydrocarbons,
2) mutagenic, and 3) induce a carcinogenic response in the
stomachs of rats and mice. The CAG, therefore, regards the use
of an intubation study to assess the carcinogenic risk of EDB
residues in food as appropriate. In addition, the risk estimates
have been adjusted to reflect the small degree of difference
in effects between dietary and gavage administration seen in
the DBCP studies.
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23
Dow Chemical Co. (Comment #34) commented that the Agency's
wholesale rejection of the Dow rat inhalation study (PD 2/3,
pp. 12-13) for risk assessment is unfortunate. Dow added that
this is the only study that examines effects after exposures
are discontinued — a situation analogous to the infrequent and
intermittent exposures experienced by workers. The Dow Chemical
Co. rat inhalation study (Nitschke, et al. , 1980) was reviewed
by the CAG.
The Agency rejects these comments. The CAG concluded that the
study is inadequate to assess carcinogenicity in rats because
1) the duration of exposure was short (a maximum of 13 weeks),
and 2) the period of observation post exposure (88 to 89 days)
was too short to determine whether it demonstrated development
of a carcinogenic response.
The FDC argued that two studies on occupational exposures to
EDB from the Octel Company were valid. The comment claims
that EPA has disregarded any epidemiology studies that show
no effects.
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24
The Agency disregarded the Octel studies, however, not because
they showed no effects, but because both embodied serious
flaws as noted in the PD 2/3.
The Ethyl Corporation, (Comment #19) discussed the Octel
mortality survey on 117 persons occupationally exposed to EDB
where employment was known to exceed four years. Ethyl noted
that the Agency position was that, since no monitoring
or exposure levels of EDB in the plant are discussed, the entire
study is useless. Ethyl Corporation asked that the EPA position
on this study be reconsidered, in view of what Ethyl characterized
as the considerable importance of this study, as evidence of
human exposures to significant levels of EDB over a period of
several years. since receipt of EDB exposure estimates from
Ethyl Corporation, the Agency has reviewed the validity of the
Octel mortality survey (CAG, 1982d). In addition to the key
argument against the study's validity, (the lack of monitoring
data on exposure to EDB, discussed in the PD 2/3), other criticisms
apply. They are as follows:
o Small study population. The study population consisted
of 117 employees. A group this size is not large enough
to adequately detect the presence of a cancer risk.
Age-specific cancer mortality rates for this study population
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25
were derived based on only 4 observed deaths in the
entire group of 117 compared against the person years
at risk (broken down by age category over the time period
1940 to 1977). These rates were then compared to rates
for similar categories in Southwest England in 1961 and
1970. It was calculated that 8.4 cancer deaths could be
expected to occur in the 117 group members during the
followup period. This is an insufficient size of a study
group, statistically, at least a 2-fold risk of cancer
generally must be found at a power equal to 0.8, in
order to detect a statistical difference at probability
of 0.05.
o Invalid cohort selection. The author decided to drop 84
people from the study for whom he had no further information
and another 29 because incomplete information indicated
a length of employment of less than 4 years. Together,
these two groups represent 47% of the original list of
214 names of individuals who had been reported to have
worked there since 1940. Because almost half of the
potentially exposed members were arbitrarily excluded
from the study, the potential for bias is considerable.
Furthermore, the criteria for exclusion of people from
the study group were loosely defined.
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26
o Duration of EDB production. Although the author notes
that this plant has produced bromine from 1940 to 1973,
nowhere is it mentioned when the production of EDB began,
although it is stated that EDB production ceased
in 1970. Because some workers may have terminated
employment before or shortly after EDB production began,
this raises the question of whether all of the 117 "selected"
employees were exposed to EDB for 4 years, the minimum
duration acceptable for this study.
In short, the methodological inadequacies of this study preclude
its use in an evaluation of the carcinogenicity of EDB to man.
The major flaws in the second Octel study, "Dibromoethane: A
survey of employee records at Almwch Factory" (Turner, 1976)
are listed below:
o Invalid age comparison. The author compared a crude
mortality rate by cause, derived from his study cohort
during the period 1960 to 1975, with an age-specific
rate of a control population of males ages 45 to 64,
residing in Gwynedd, Wales in 1974. The average age of
the cohort population was 40; the average age of the
control group was much higher. Therefore, because of
the differences in the ages of the groups, the comparison
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27
of the two groups could not be expected to demonstrate
any excess mortality in the study group. Details of
this calculation are addressed in the CAG memo addressing
comments to EDB risk (CAG, 1982b).
o Invalid person-years calculation. Twenty-eight deaths
in the study group were noted during the period 1960 to
1975, yet person-years were counted as if those who died
lived to the end of 1975. This biased downward the
death rates of the study group.
o Small study group. As in the first Octel study, the
size of the population is not statistically large enough
to assure that it would detect the presence of a significant
cancer risk.
In summary, the two studies described above are not considered
to be adequate to evaluate the carcinogenic potential of EDB.
2. Mutagenicity
The Agency did not receive any comments regarding the
presumption of mutagenicity. The Agency concludes that the
qualitative mutagenic criteria are fully established for EDB
In addition, the mutagenic properties of EDB support the Agency's
position that EDB is a direct acting carcinogenic agent.
Since the Agency issued the PD 2/3, the state-of-the-art in
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28
mutagenic risk assessment has developed to the point where
one can attempt to estimate risk to humans exposed to many
chemical mutagens (Banbury Report 1979). The Agency is working
toward the goal of basing regulatory decisions on quantitative
mutagenic risk assessments. Until the Agency has such a capa-
bility, our regulatory position is to reduce exposure to mutagens
to the lowest levels practicable.
3. Reproductive Effects
Two unpublished studies addressing the adverse reproductive
effects of EDB were submitted in response to the PD 2/3.
These studies are discussed below.
a. Ter Haar, 1981
Ter Haar (1981) compared the frequency distribution of sperm
concentrations in workers exposed to EDB with the frequency
distribution in clinical studies of fertile men (Smith and
Steinberger, 1977, Nelson and Bunge, 1974). He reported that
these frequency distributions did not differ significantly.
The Agency concludes that there are a number of inadequacies
in the Ter Haar (1981) study. Some of the more significant
ones are:
o The criteria for determining adverse reproductive function
are not defined.
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29
o No attempt was made to determine if sperm concentration
from workers exposed to EDB accurately reflected true
daily sperm production.
o There was no matching control group, and there was no
adequate comparison made between exposed and non-exposed
workers.
Because of these and other inadequacies, this study cannot be
accepted as useful evidence for the lack of adverse reproductive
effects in workers exposed to EDB.
-------
30
b. Levine et al., 1981
Levine and his coworkers attempted to perform an epidemtological
study of fertility in male workers exposed to EDB. They compared
the average number of children born to the spouses of married
workers with the average number of children born to all females
in the U.S., as reported by the National Center for Health
Statistics.
In this study, it was assumed that the reproductive health of
workers exposed to EDB was not adversely affected because the
average number of children born to the spouses of the workers
was similar to averages reported in the national statistics.
The major deficiencies in this study are:
o The most significant deficiency is the lack of sensitivity
for detecting adverse reproductive effects.
o The investigators did not evaluate a large enough
population of unexposed workers to make a comparison of
fertility. Because of the lack of an adequately matched
control population, this study cannot discern whether
potential differences are the result of exposure to EDB
or other confounding variables.
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31
o The investigators did not consider such factors as the
desire of workers to have children or use of contraceptives
to control fertility. An observation that an individual
has produced offspring does not exclude the possibility
of serious reproductive consequences such as subtle
decrease of fertility, problems in sexual performance or
reduced libido.
The deficiencies in this study preclude its use to determine
a measureable effect of EDB exposure on fertility. Because of
these deficiencies, this study cannot be accepted as evidence
for the lack of adverse reproductive effects of workers exposed
to EDB.
An additional comment relates to both studies. Neither study
examined the possibility of adverse reproductive effects in
female workers. To adequately address the possibility of
adverse effects in all workers, it is also necessary to evaluate
reproductive ability in both sexes, and evaluate pregnancy outcomes
of women exposed to EDB.
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32
c. Conclusion
Two recent studies (Ter Haar 1981; Levine et al., 1981) have
been sumbitted in response to the Agency's presumption in
the PD 2/3 of adverse reproductive effects resulting from
exposure to EDB. These studies attempt to show that there is
not a significant difference between fertility of workers
exposed to EDB and fertility of the general population. Because
they contain numerous deficiencies, these reports do not rebut
the presumption of reproductive effects as described in PD
2/3. The Agency's detailed analysis of these studies is
contained in "REAG Response to Industry Rebuttals Concerning
The Reproductive Risks of EDB" (REAG, 1982).
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33
III. Revisions and Amendments to PD 2/3; Exposures and
Associated Health Risks
A. Applicator Exposure
Subsequent to the publication of the PD 2/3, the Agency received
substantive additional information regarding four applicator
exposure situations. Therefore, the Agency has revised the
original estimates of applicator exposure for preplant soil
fumigation and quarantine fumigation of citrus, and completed
an exposure analysis for fumigation of felled logs and the
post harvest fumigation of papayas.
1. Preplant Soil Fumigation
RDB inhalation exposure of soil fumigation applicators has been
reassessed based on two factors (Reinert 1982 c). First, use
information, more reliable than that used in the PD 2/3, was
provided to the Agency in the comments of Great Lakes Chemical
Corp. (Comment #24). Second, new exposure studies for this
use pattern were provided by Dow Chemical Co. in their comments
on the PD 2/3 (Comment #34).
The Agency estimates that the use of certain specified types of
respirators during all phases of application would reduce
inhalation exposure by about 90%, at the peak efficiency of
the respirators, assuming no breakdowns, malfunctions, or
improper use of the equipment (dermal exposure is assumed to
be insignificant compared to inhalation for this use).
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34
Based on the new data on average air levels encountered during
transfer and application, use of respirators solely during the
transfer of the pesticide could possibly reduce exposure by
approximately 80%. The additional data have been combined
with the data used in the PD 2/3 and new averages determined
as shown in Table 1.
Table 1. Data on EPS Air Levels During Transfer and Application
PD 2/3 avg. New data Revised exposure
(mg/m^) (mg/ra^) (mg/m^)
Application 0.81* 14.6, 10.8 1.9
(open cab) 3.8, 0.54
Transfer 3.03** 484, 238, 36.1 114.0
(open system) 27.7, 7.7
* Average of 21 data points
** Average of 2 data points
Recently, additional applicator exposure data related to the soil
fumigation use of EDB has been made available to the Agency (CDFA,
1983). The levels of EDB measured in the air during application
are consistent with values in Table 1. Air levels measured while
loading the chemical are considerably lower than those in Table
1. This is expected because closed mixing and loading systems
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35
were employed in the CDFA study.
Potential dermal exposure to the hands was measured in this
study. The results are consistent with the assumption that
potential dermal exposure will be insignificant compared to
potential inhalation exposure for this use pattern.
The revised respiratory exposure estimates for applicators
engaged in soil fumigation using open transfer systems and
open cabs are shown in Table 2.
418-574 0-83-4
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36
Table 2. EPS Respiratory Exposure During Soil Fumigation
Use Site
Duration of
annual exposure (hrs)
Fruit trees
Tobacco
Peanuts
Pineapples***
Misc. vegetables
and fruits
Transfer
0.8
1 .8
1.5
24.5 - 43.0
2.6-7.8
Application
7.2
16.2
13.5
220.5 - 387
23.4-70.2
Annual
inhalation
exposure (mg/year)**
130
280
240
303.3 - 532.4
410-1200
Sweet potatoes
Irish potatoes
Cotton
Citrus
8
8.1
2
0.8
72
72.9
18
7.2
1300
1300
310
130
* data from Great Lakes Chemical Corp., Table II of exhibit 2 of their
rebuttal package.
** dermal exposure is assumed to be insignificant compared to inhalation
exposure.
*** prom PD 2/3, where it was noted that this may be an overestimate of
exposure for this crop, because different agricultural practices are
employed in the fumigation of pineapple fields.
Sample calculation: using as an example the use site "fruit
trees"; 1.2 m^/hr (7.2 hours app./year x 1.9 mg/m3 + 0.8
hours trans./year x 114 mg/m3) = 125.8 mg/year.
2. Quarantine Fumigation
The Agency has received information from the Florida Department
of Citrus demonstrating that work at citrus fumigation stations
and warehouses should not be classified as "heavy activity."
The breathing rate for "moderate activity" (1.2 m5/hr) has
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37
therefore been used to revise the applicator and warehouse
worker respiratory exposure calculations. The Agency has also
received additional worker monitoring data from the Occupational
Safety and Health Administration (OSHA, 1981) on exposure to
truckers and fumigation station personnel. This information
has been used by the Agency to revise exposure estimates for
citrus fumigation.
The additional data have been used to revise the Agency's
estimates of respiratory exposure to workers involved in
quarantine fumigation. Two types of new data are utilized in
the Agency's revision of respiratory exposure. The breathing
rate was reduced from 1.8 ra^/hr. for heavy labor (listed in
PD 2/3) to 1.2 m^/hr. for light to moderate labor. The results
are lower estimates of exposure to EDB per year. The second
kind of new data is EDB worker monitoring data now available
which were not available for the PD 2/3 assessment. The revised
exposure estimates are presented in Table 3.
The Agency has received information from the Papaya Administrative
Committee regarding the flow/work practices of papaya shippers
in treating fruit with EDB (Comment #23). The Agency previously
had no information on the treatment of fruit in Hawaii. The
Papaya Administrative Committee states that in Hawaii, fruits
are delivered to the packing houses in wooden field bins. The
fruits remain in these containers through fumigation until
they are hand-packed. After hot water treatment at approximately
120° for 20 minutes for partial fruit fly disinfestation and
disease control, the fruits are dried and fumigated according
to APHIS requirements. Following EDB fumigation, fruits are
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Table 3. Revised EDB Inhalation Exposure of Workers at Citrus Fumigation Stations and at a Citrus warehouse
Location Workers Concentration
of EDB (mg/m3) Number Breathing Hrs/dayV
Avg. of samples Rate (m3/hr)V
Wahneta - Indoor operators
Ft. Pierce - Indoor operators
Wahneta - Outdoor operators
Ft. Pierce - Outdoor operators
Wahneta - Truckers/Station
Personnel
Ft. Pierce - Truckers/Station
Personnel
OSHA £/ Truckers/Station
Personnel
Wahneta - Truckers
OSHA6/ Truckers (during
coupling and uncoupling)
OSHA6/ Truckers (on road)
Tampa - Forklift operators,
Laborer (inside)
Tampa - Forklift operators,
Laborer (outside)
Tampa - "Stickmen"
OSHA6/ "Stickmen"
0.207
0.607
0.406
0.280
0.048V
1.092
0.18
1.93
4.26
0.07
8.99
2.727/
4.75V
2.36
1.65V
2.00V
4.76
8.57
14
1
19
2
3
1
9
2
5
5
1
unknown
5
3
unknown
17
2
6
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
8
8
8
8
8
8
8
0.08
0.08
8
8
8
8
'8
8
8
8
8
Ceys/yrV
112
112
112
112
112
112
112
112£/
112£/
112
155V
155?/
155V
155V
155V
155V
155£/
155V
Avg. exposure to
EDB (mg/kg/yr)4/
3.2
9.4
6.2
4.4
0.8
1.4
2.8
0.2
0.6
1.1
192
58
101
50
35
42
101— r
182
1. Assuming light activity (Specter, 1956).
2. Hrs./day are variable depending on work load during year. Average 8 hr. work day is assumed here.
3. Data from APHIS (1977)
4. Assuming a 70 kg worker.
5. Including "non-detectable" samples at level of detection (0.008 m3).
6. OSHA survey 1981 draft report
7. From Florida Citrus Rebuttal
8. Assuming trucker returns once each day
9. Assuming 22 working days a month over the period of October 11—through May 14.
CO
oo
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39
typically stored until packing time. The fruits are then
culled, sized and handpacked into cardboard cartons.
The Agency has received information from the Hawaii
Papaya Industry Association regarding exposure to applicators
fumigating papaya with EDB (Hertlein and Hagadone, 1981). EDB
concentrations were measured in the ambient air of the fumigation
area. EDB levels ranged from 0.1 to 3.6 ppm; the average
concentration was 0.86 ppm or 6.6 mg/m3. The Agency has
calculated an applicator exposure of 10 mg/kg/yr using the
following assumptions.
o The EDB concentration in the ambient air is representative
of applicator exposure.
o Applicators perform "light" to "moderate" work at a
respiratory rate of 1.2 m^/hr.
o Applicators are exposed for 10 minutes per load of
papayas fumigated.
o An applicator fumigates 530 loads per year.
o An applicator weighs 70 kg.
Sample calculation:
6.6 mg/m3xl.2m3/hr x 88 hr/yr x 1/70 kg = 10 mg/kg/yr
The person assigned to the job as applicator at papaya fumigation
station is very often also assigned to operate a fork lift to
move bins of fruit from one operation to another. Workers
removing papaya from fumigation chambers would be exposed to
air concentrations of EDB from 0.07 to 1.6 ppm; the average
concentration was 0.54 ppm or 4.2 mg/m3. Workers removing
papaya from refrigators after fumigation would be exposed to
air concentrations of EDB ranging from 0.02 to 0.53 ppm; the
average concentration was 0.36 ppm or 2.8 mg/m3 (Hertlein and
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40
Hagadone, 1981). The Agency has calculated worker exposure of
8 mg/kg/yr and 6 mg/kg/yr, while moving bins of fruit from the
fumigation chamber and refrigators, respectively (Ludvik,
1982; Saito, 1982).
Fruit sorters and packers are exposed to air concentrations of
EDB ranging from 0.09 to 0.22 ppm; the average concentration
was 0.14 ppm or 1.1 mg/rn^. Assuming a 60 kg woman works an 8
hour day, 5 days per week and 48 weeks per year, she would
be exposed to 42 mg/kg/yr of EDB. If the woman works an 8 hour
day, 3 days per week and 50 weeks per year, she would be exposed
to 26 mg/kg/year (Ludvik, 1982; Saito, 1982).
A summary of all applicator exposure estimates is presented in
Table 4.
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Table 4. Sunroary Table of FD 4 Applicator Exposure Estimates Compared with Exposures fron FD 2/3
mg/kg/year I/
Wbrkers at Citrus Fumigation
Stations In Fla. 3_/ (inhalation)
W - indoor operators 4/
FP - indoor operators
W - outdoor operators
FP - outdoor operators
W - truckers/station personnel
FP - truckers/station personnel
OSHA - truckers/station personnel
W - truckers
OSHA - truckers (during coupling)
OSHA - truckers (on road)
T - forklift operators/laborers (inside)
OSHA - forklift operators/laborers (inside)
T - forklift operators/laborers (outside)
OSHA - forklift operators/laborers (outside)
T - "stickmen"
OSHA - "stickmen"
Hawaiian Papaya
Applicator
Packer/Sorter
Indoor laborer
Felled log 2/
Applicators
PD 2/3
4.8
14
9.4
6.5
1.1
2.1
0.4
287
75.3
151.8
PD 2/3
PD 4
dermal
inhalation
3.2
9.4
6.2
4.4
0.8
1.4
2.8
0.2
0.6
1.1
192
101
50
42
101
182
10
26-42
14
PD 4
69
24
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Table 4 Continued. Summary Table of PD 4 Applicator Exposure Estimates Compared with Exposures from FP 2/3
mg/kg/year I/
Soil Fumigation: pp 2/3 FD 4
Applicators (inhalation)
tree site 0.01 1.9
tabacco 0.18 - 0.44 4.0
peanuts 0.21 3.4
Misc. fruits 0.18 - 0.92 5.9 - 17
& vegetables
sweet potatoes 0.034 - 0.053 19
Irish potatoes 0.07 - 0.12 19
cotton 0.35 - 1.8 4.4
citrus (preplant) 0.44 - 0.56 1.9
pineapples 4.3 - 7.6 4.3 - 7.6
citrus (barrier) 7.4 7.4
Spot treatment >U
applicator 4.3 - 59.3 4.3 -59.3
mill worker 9.4-10.9 9.4 - 10.9
I/ body weight = 60 kg for packers/sorters for papaya, 70 kg otherwise.
2/ for this use pattern, the number of years an individual would work as a fumigator is estimated to be
1.25 years/lifetime (4).
3_/ exposure stidies for workers involved in citrus fumigation in California have been carried out (18,32),
and these studies have been evaluated (33, 34). However, the use information (annual and lifetime durations
of exposure) necessary for exposure assessment is unavailable.
4/ W = Wahneta; PP = Ft. Pierce; T = Tampa
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43
3 . Felled Log Fumigation
In the PD 2/3, the Agency reported that there were no data
available on EDB exposure to felled log applicators. The
Agency has since obtained data on EDB air concentration during
felled log application (USDA, 1973), use rate information
(Day, 1981a and EPA, 1981), and surrogate data on dermal
exposure to 2,4,5-T resulting from a similar application method
(Lavy et al. , 1980). The Agency has estimated EDB exposure
to felled log applicators based on these data. The exposure
estimates assume a breathing rate of 1.2 m^/hr. for moderate
activity, and that the average applicator weighs 70 kg. The results
are summarized in Table 5 below.
Table 5. Estimated EDB Exposure to Felled Log Applicator
mg/hr. mg/day mg/yr. mg/kg/lifetime*
Dermal 75 300 4800 86
Respiratory 26 104 1664 30
* 1.25 years/lifetime spent in application (Ludvik, 1982). In using
these surrogate data to estimate EDB exposures, the Agency recognizes
that questions have been raised regarding whether the Lavy patch data
adequately represent the amount of dermal exposure to the applicators,
However, at this time, the Lavy data are the best data available to
the Agency which can be extrapolated for this particular use pattern.
Therefore, the Agency is using these data with the understanding that
any EDB exposure assessment, based on these data, is subject to the
same qualifications and limitations as the original Lavy data.
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44
B. Applicator Risk
The Agency's Carcinogen Assessment Group has estimated the
cancer risks associated with occupational exposure to EDB in
quarantine fumigation of citrus, quarantine fumigation of
Hawaiian papayas, felled log fumigation, soil fumigation, and
spot fumigation of grain milling machinery. Risk figures were
derived using the original linear non-threshold model discussed
in the PD 2/3. These risk figures are based on a rat inhalation
study (McGaughy, 1982) and are presented in Table 6.
The Agency calculated risk figures for applicator by assuming
that the major route of applicator exposure will be via in-
halation. For the felled log treatment the Agency does assume
that dermal exposure could be a significant route of exposure.
In addition to the exposure received on the job, workers will
also be exposed to a similar amount of EDB in their diet as will
the general public. Some workers, particularly those involved in
soil fumigation, may also be exposed to contaminated drinking water.
Proper use of respirators, operating at peak efficiency, during all
phases of application could reduce inhalation exposure by about 90%,
and could result in similar reduction in increased cancer risk.
It should be noted that this estimate assumes that that the
respirator is in good repair, properly fitted, and worn at all
times that an exposure potential exists. The latter consideration
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45
is particularly important because some tasks e.g. packing and
sorting papayas and soil injection, could result in low levels
of EDB for approximately 8 hours per day. Physiological and
psychological limitations make wearing a respirator for extended
periods highly unlikely (NIOSH, 1976).
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Table 6. Revised Cancer Risk Due to Occupational Inhalation of EDB
Exposed group
Range of exposure
(mg/kg/day)
Lifetime probability
estimates
No. of workers
exposed
Soil injectioh (6)
f armer/applicator
Quarantine fumigation (6)
(Florida citrus)
station indoor
operator
station outdoor
operator
trucker/station
personnel
warehouse indoor
laborer
warehouse outdoor
laborer
warehouse stickman
Quarantine Fumigation (6)
(Hawaii papaya)
applicator
3.0 x IP"3 - 3.0 x 10~2 3.5 x 10~3 - 3.5 x 10~2 14,000
5.0 x ID"3 - 1.5x 1(T2
6.9 x ID"3 - 9.7 x 10~3
3.1 x 10-" - 4.3 x ID"3
1.6 x ID"1 - 3.0 x ID"1
6.6 x 10-2 - 7.8 x 10~2
1.6 x lO-1 - 2.8 x 10"1
1.5 x 10-2
5.9 x 10-3 - 1.7 x 10~2 nl/
8.1 x 10-3 - 1.1 x ID"2 10V
3.6 x 10~4 - 5.0 x lO"3 lo£/
1.7 x 10-* - 3.0 x HT1 4-i-
7.4 x 10~2 _ 8.7 x 10-2 4_10
1.7 x 10-1 - 2.8 x 10-! 4-10
1.7 x ID"2
as
sorter/packer
indoor laborer
Spot fumigation (4) (6)
applicator
millworker
Felled log treatment
Inhalation
dermal
total
4.1 x 10-2 _
9.1 x 10~3 -
6.6 x 10-3 _
1.5 x 10-2 -
1.2 x 10-3
3.4 x 10-3
6.9 x 10-2
1.3 x 10-2
9.1 x iO-2
1.7 x 10-2
4.7 x lO"2 - 7.8 x 10"2
1.0 x 10-2- 1.4 x iQ-2
7.7 x IO-3 - 1.0 x MT1
1.7 x 10~2 - 2.0 x lO"2
1.4 x ID"3
8.4 x 10-2
9.5 x 1Q-* (5)
unknown
unknown
2400 - 6000
16,000
unknown
(1) Assumed that 31 federal and state employees are evenly distributed. (Mittelman 1980)
(2) Per warehouse, Seasonal variation. Assumed that 12-38 laborers per warehouse are evenly distributed (Mittelman 1980)
(3) Ludvik 1982c
(4) Figures have not been revised - no additional data received since publication of EDB PD 2/3.
(5) Based on an inhalation model, assuming 100% absorption and 1.25 years of application exposure/lifetime.
(6) Exposure is without proper use of respirator.
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47
C. Dietary Exposure from Quarantine Fumigation
The Agency has modified the PD 2/3 estimates of the dietary
exposure resulting from fumigation of citrus and tropical
fruit in three significant ways. First, the citrus food factor
pertaining to the consumption of fresh fruit has been used,
rather than the factor for all citrus (both fresh and processed).
This change has been made because EDB is used only on fruit
destined for the fresh market. Second, residue data on the
edible portions of citrus and tropical fruit has been used,
rather than data on the whole fruit. Use of whole fruit in
estimating exposure tends to exaggerate true dietary exposure,
because EDB residues tend to concentrate in the peel and seeds
- portions of. the fruit which are not typically consumed.
Some consumers of treated citrus do consume portions of the
citrus peal; dietary exposures to those persons would be
underestimated.
Further, in response to a recommendation by the FIFRA
Scientific Advisory Panel, the Agency has used additional data
that were not previously available for residues of EDB in
citrus and tropical fruit. A recent study by the California
Department of Food and Agriculture (CDFA) has been used (Maddy
et al., 1981a). In this study, samples of fumigated fruit
originating in Florida, Texas and Mexico were randomly taken from
wholesale and retail markets in California and analyzed for
EDB. Normal commercial practices, such as typical time intervals
from fumigation to the store shelves, were assumed. Third,
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48
more accurate estimates of the percent of fumigated fresh
fruit on the grocery shelves in various geographical areas
have been used rather than assuming a uniform national average
treatment of 2.6% of fresh citrus and 72% of fresh tropical
fruit. This change has been made because certain states, such
as California, require fumigation of most incoming citrus and
tropical fruit, while other states do not require fumigation
of any fruit. Thus, California consumption of fumigated fruit
exceeds the national average. We expect dietary exposures,
calculated for California, to also be representative of other
locales which require fumigation. These areas include Texas,
Arizona and New Mexico.
In addition, data collected by USDA's Agricultural Marketing
Service indicate that most fresh citrus imported from Mexico
(all of which is treated with EDB), is shipped to the Southwestern
and Western U.S. Although data specifically identifying the
amount of citrus shipped to the individual states is unavailable,
the Agency believes that this contribution would increase dietary
exposures in the Southwestern and Western U.S.
If such data were available, the estimate of the total volume
of EDB treated citrus consumed in California would be larger,
i.e., it would include both domestically produced EDB-treated
citrus and imported EDB-treated citrus. The USDA data further
indicates that a small volume of the citrus shipped from
Florida to California is ultimately shipped to Hawaii and
consumed there. Although exact figures are not available,
this will result in a slight overestimate of the California-
consumed citrus treated with EDB. The Agency does not expect
the proportion of EDB-treated citrus consumed in Hawaii to
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49
differ significantly from the national average (Zygadlo,
1982b). A summary of the data collected by CFDA prior to
1982 on residues of EDB in the edible portions of citrus and
tropical fruits is shown in Table 7.
Table 7. Residue Levels in Edible Portion of Fruit (ppm) \
Number of Range of
Samples Analyzed Values Observed^/ Mean 4/
Grapefruit
Limes
Papaya V
Mangos
Lemons
Oranges
24
10
35
27
3
6
ND
ND
ND
0.002 -
ND
0.326
0.01
0.102
0.27
ND
0.24
0.051
0.0013
0.011
0.057
ND
0.048
(1) Source: Maddy, K.T. jrt aj. . , CDFA Report HS-959, Oct. 21, 1981b.
(2) Limit of detection of analytical method is 2 ppb.
(3) Wholesale and retail samples combined.
(4) Non-detectable samples were assigned a value of zero.
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50
More recent data (CFDA, June 2, 1983) has shown residues of EDB
in fruit can be even higher:
Commodity Origin Date Sampled EDB Residues (PPM)
Grapefruit
Grapefruit
Oranges
Texas
Texas
Texas
2/2/82
2/4/82
1/23/82
Pulp
0.28
0.21
0.88
These data indicate that there may be significant seasonal
variations in the levels of EDB residues in fumigated citrus.
Three composite samples, shown above, (2 grapefruit and one
orange which were fumigated in Texas and collected by CDFA in
California in January and February, 1982) showed signficantly
higher levels of EDB than the CDFA samples used for the dietary
exposure assessment. The residue levels used in the dietary
risk assessment in this document were obtained from fruit
which were collected in September and October of 1981.
The average lower temperature in the winter months are likely
to be responsible, at least in part for the observed difference
in residue levels (Maddy, K.T. personal communication to J.C.
Reinert, EPA, August 12, 1983). In addition, the Agency received
a preliminary report from the Agricultural Research Service,
USDA and the Florida Department of Citrus on factors affecting
residue levels in grapefruit fumigated with EDB (USDA, 1983).
These reports demonstrated that at the current treatment rate
both time and temperature are factors in reducing EDB residue
levels in the edible portion of grapefruit.
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51
Although elevated storage temperatures resulted in lowered EDB
residues, temperature was not as significant as time in reducing
EDB levels (USDA, 1983). Because this report was a controlled
study, not a monitoring study of fruit residues in commerce - it
is not useful for estimating dietary levels. The results, however,
are not inconsistent with the exposure data for California used
in this document.)
Arizona, California, New Mexico and Texas require fumigation of
all fresh citrus shipments from Florida. Additionally, Arizona,
California and New Mexico require fumigation of fresh citrus
shipments from Texas. However, because of the success Texas has
had with their Mexican fruit fly erradication program, only
about 20% of citrus shipped from Texas to these states had to be
fumigated this past growing season. Dietary exposure estimates
for domestic citrus were developed for California based on
1982 historical Texas and Florida citrus fruit shipment data
(Zygadlo, 1982a). This information indicated that 17% of fresh
oranges, 35% of fresh grapefruit and 4.4% of other fresh citrus
consumed in California were fumigated with EDB. Since the 1982
data were developed, the California dietary exposure estimates
may need to be reduced due to the success of the Mexican fruit
fly certification program in Texas. Information submitted to
the Agency from CDFA indicate that, a smaller percentage of
citrus consumed in California may be fumigated, than indicated
in the 1982 estimates, but, CDFA estimates have not yet been
confirmed. The dietary burden to California consumers is shown
in Table 8 using the original 1982 estimates.
418-574 0-83-5
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52
Table 8. EDB Dietary Burden from Quarantine Citrus Fumigation
in California
% of diet
mean residue fresh
Fruit level (ppm) fruit
Oranges 0.048
Grapefruit 0.051
Lemons and limes^/ 0.001
Other citrus 0.025
1.35
0.82
0.17
0.48
% of fresh dietary bur
fruit (mg/kg body
treated 5/ weight/day) ^
17 2.75
35 3.66
4.4 1.86
4.4V 1.32
Total 6.54
x 10~6
x ID"6
x 10-9
x 10~7
x 10"6
4/
(1) Assumed to be the same as for "miscellaneous citrus"
(2) The Agency has conflicting information on the percent of
lemons and limes which are fumigated with EDB. Their
estimated contribution to the dietary burden is insignificant
regardless .
(3) Sample calculation using "oranges" as an example: Dietary
burden = (0.048 mg/kg diet x (1.5 kg food consumed/day) x
(1/60 kg) x 0.0135 [fraction of diet which is fresh
oranges] x 0.17 [fraction of consumed fruit which has been
treated] = 2.75 mg . EDB/kg . b. w./day .
(4) If Mexican Citrus is included, the addition to dietary
exposure (Reinert, 1982, DB = 0.411 x 10~6 mg/kg/day)
to the above total (6.54 x 10~6 mg/kg/day) yields a
grant total of 6.95 x 10~6 mg/kg/day.
(5) Based on the 1982 estimate discussed on the previous page.
In states which do not reguire incoming domestic shipments of
fruit to be fumigated with EDB, dietary exposure to EDB will
still exist from consumption of fumigated imported Mexican .
citrus and imported tropical fruits. Mexican citrus accounts
for 1.38% of the overall fresh market in the U.S. Fumigated
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53
tropical fruits account for 72% of the fresh tropical fruit
market in the U.S. In the absence of specific data, the Agency
will assume that this fruit is uniformly distributed across
the country.
Table 9 compares the PD 2/3 and PD 4 estimates of the total
dietary burden which results from the use of EDB as a post-
harvest fumigant of citrus.
Table 9. Dietary Burden Comparison; Citrus*
(mg/kg body weight/day)
PD 2/3 1.2 x in"5
PD 4 (non-CA 4.1 x 10~7
residents)
PD 4 (CA residents) 6.9 x 1CT6
*Including the contribution from Mexican citrus
and using the 1982 estimates of percentage of
fresh fruit treated.
The calculations below present the dietary burden estimates
for a "tropical fruit eaters". It is assumed that "tropical
fruit eaters" consume 12 fruits/year. These individuals
constitute a small portion of the U.S. population. Since the
average EDB residue contamination has been determined to be
0.031 ppm (=0.031 mg EDB/kg fruit, the average residue level
for the all papaya and orange samples) (Reinert, 1982) then the
dietary burden for tropical fruit (mangos and papayas) can be
estimated as follows:
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54
Example Dietary Burden Calculation for Tropical Fruits
1 yr. 0.25 kg.* 0.031 mg
DB = 12 fruits/yr. x 365 days x fruit x kg.
x _1
60 kg b.w.
DB = 4.25 x 10~6 mg EDB/kg/b.w./day
* 0.25 kg, the average weight of the edible portion of
papayas and mangos.
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55
D. Contamination of Wheat By-Products from Bulk Grain and
Spot Treatment of Grain Milling Machinery with EDB
Grain Fumigation
On February 27, 1980 a re-evaluation of the total dietary
burden of EDB with respect to the post-harvest grain uses was
submitted to Special Pesticide Review Division (J.W. Holder,
RGB ro R. Johnson SPRD). In that review it was estimated
that the "probable" residue level for EDB in wheat bread
derived from grain fumigated after harvest with EDB would be
0.07 ppb (.008 ppb from on-farm and 0.062 ppb from off-farm
uses). It was also estimated that the "realistic worst
case" level which assumed that the grain would be treated
at the maximum rate, not mixed with untreated wheat (no
dilution), and minimum commercial transit times (minimum
opportunity for dissipation of residues) would be 31 ppb EDB
(7.2 ppb from on-farm and 23.4 ppb from off-farm uses). A
third estimate using a mass-balance approach yielded an
estimated contamination level of 87 ppb.
Since the above modeling estimates were made, the results of an
investigation of actual residues in wheat flour from commerce,
and biscuits produced from that flour has been published (D.
Rains and J. Holder, J.O.A.C 64, (5), 1981, pp 1252-1254).
The flour analyzed in the investigation were geographically
representative of cities throughout the continental U.S.
All but one of the twenty-two flour samples contained detectable
levels of EDB (more than 0.5 ppb). The reported levels in
flour ranged from ND to 4,200 ppb. Twenty of the twenty
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56
two biscuit samples baked from the flour also contained
detectable levels of EDB. The levels reported to have survived
the baking process ranged from ND to 260 ppb and averaged
35.7 ppb.
If these data are indicative of the actual residues in U.S.
finished wheat products, they indicate that the "probable"
case underestimated EDB levels, and that actual levels may
approach the "realistic worst case" level of 31 ppb.
Therefore, it is now the Agency's judgement that the "realistic
worst case" level is the more appropriate estimate for the
dietary burden from bulk grain uses, rather than the "probable
case" estimate used in the PD 2/3. Thus, 31 ppb EDB in grain
products is equivalent to a dietary burden of 8.0x10"^ mg
EDB/ks/day for a 60 kg person consuming 1500g of total food
per day.
Spot Fumigation
As discussed previously in PD 1 and PD 2/3, the available
residue data reflecting the levels of EDB in grain products
processed in mills spot-treated with EDB are of limited
value. All of the available studies involved wheat with
significant levels of EDB before milling.
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57
However, even though these data are not adequate to determine
with certainty the residue levels expected in much of the
flour milled during the four weeks between treatments, they do
show that spot fumigation does contribute significant residue
levels of EDB based on a time-weighted average over the period
of the month between treatments.
In the PD 2/3, the estimate for the residue levels contributed
by spot fumigation was based on a 1978 Litton Bionetics study
for Ferguson Fumigants, Inc. The estimate of 68 ppb in flour
(based on a time-weighted-average over four weeks) made no
correction for the levels of EDB in the incoming wheat grain
because the exact portion of these EDB residues that transferred
to the flour (and thus to wheat by-products) was unknown, and
because several investigators have reported that the majority
of these are retained by other milling fractions (such as
bran, offal, shorts, germ, etc.). However, even if it is
assumed that all the EDB residues detected in the incoming
wheat were concentrated in the finished flour, the available
data still indicate that the spot fumigation contributed significant
residues of EDB to the flour. It has been reported that EDB
levels in the incoming grain ranged between 30 to 50 ppb.
Assuming that all the EDB was concentrated in the finished
flour, the resulting levels would be 43 to 71 ppb in flour.
If these calculated background levels are subtracted from the
levels actually reported for flour (which ranged from 54 to
1,410 ppb), the calculated time-weighted-average residue level
would be 34 ppb. Thus, the 34 ppb appears to be the minumum
net increase, over time between fumigations, that results in
wheat flour from spot fumigation.
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58
Accordingly, it continues to be the Agency's judgement that
the spot fumigation use contributes significantly to the
dietary burden of EDB, and that 3 ppb in finished baked products
(based on 68 ppb in flour) is a reasonable estimate of the
expected dietary burden. Thus, 3 ppb EDB in grain products
is eguivalent to a dietary burden of 5.8 x 10~^mg EDB/kg.
b.w./day for a 60kg person consuming 1500g of food/day.
This is calculated from the worst case (J. Holder,1980)
DB = 7.7 x 10~6 times 3/4, where 3/4 of the mills are
estimated to use EDB for spot fumigation use.
The Agency is continuing to monitor for residues of EDB in
grain, flour, and finished baked goods. This monitoring is
being undertaken in coordinated interagency efforts with
USDA and the Food and Drug Administration. In addition to
flour and baked goods, milk, and meats including beef, poultry
and pork are being sampled. The Agency will continue to
evaluate these data to establish a more complete understanding
of the extent of hazard to public health resulting from
fumigation of stored grains and spot fumigation of grain
milling machinery. If the extent of the hazard posed by
either or both of these uses of EDB becomes more clearly
delineated and defensible, the Agency will consider emergency
suspensions for these uses.
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59
E. Ground Water Contamination
As of September 16, 1983, BOB has been found in water
from approximately 114 different wells in four states. In all
cases, EDB use as a soil fumigant is an extremely likely
cause or is at least a possible cause of the contamination.
A summary of the monitoring data follows. A discussion of
the persistence and transport of EDB follows after the monitoring
summary, along with a discussion of the possible significance of
gasoline leakage to the contamination in ground water.
1. Monitoring Results
In 1980, the EPA helped design and sponsor a ground water
contamination study by the California Department of Food and
Agriculture. The object of the study was to determine the
extent and mechanism of ground water contamination by four
pesticides in certain areas of California. EDB was one of
the chemicals selected, and the draft report* indicated that
two wells out of over two hundred sampled** were contaminated
* The final report is being written in three volumes which are
presently in various stages of peer review.
** Not all of the wells sampled were near EDB use sites.
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60
with 0.1 ppb and 0.2 ppb EDB (Zalkin, et al., in progress).
More importantly, EDB was found at concentrations between
0.1 and 31 ppb in the soil at depths greater than 20 feet,
moving down to ground water. Since these preliminary reports
were received in spring, 1983, EDB has been found in ground
water in 16 different counties in the states of California,
Florida, Georgia, and Hawaii. The levels reported vary
between 0.02 ppb and ca. 300 ppb, and are typically between
0.05 and 5 ppb. The results are summarized in Table 10, and
a state-by-state discussion follows.
Table 10 EDB Ground Water
Contamination Known or Suspected
to be Due to Agricultural Use
States
California
Florida
Georgia
Hawaii
Total
No. of Counties
5
9
1
1
16
No. of Positives
(approx. )
18
86
6
L 4
114
Typical Positives
(ppb)
0.1-2.0
1.0-15.0
0.1-10.0
0.02-0.1
0.05 - 5.0
In general, the detectable levels of EDB cited above
have been confirmed by two gas chromatography (gc) methods
and/or gc-mass spectrometry when possible.
a. California
The monitoring has been done by the Department of Food
and Agriculture, the State Water Resources Control Board,
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61
and the Department of Health Services, with some assistance
from EPA. The 15 to 20 positives have been in the San Joaquin
Valley area. Approximately two small community drinking water
supplies have been contaminated. Probably 250 to 300 water
samples have been negative for EDB over the last four years,
in California, but for many of these negatives:
1) it is not known whether EDB had been used near
(ca. 1/4 mile) the wells;
2) the number of years of EDB use have often not been
known;
3) and, the minimum detection limit at the time of sampling
was higher, making it more difficult to detect low
levels of EDB than it now is.
State agriculture and health officials have concluded that
in most, if not all, cases contamination is likely due to
EDB use as a soil fumigant. (A single positive in Solano County
has not been included in this assessment because it may have been
due to poor industrial practice.)
b. Florida
Two different areas of Florida have been sampled since
mid-1983 and both areas contain ground water contaminated
with EDB. Those areas are an eight county citrus growing
region in central Florida, and the soybeans/peanuts area of
Jackson County, in the panhandle.
As of early September, 1983, 86 out of 334 wells sampled
contain detectable levels (> 20 parts per trillion) of EDB; 75
of these 86 positives contain EDB concentrations greater than
the level 0.1 ppb (Bigler, 1983), which the state has selected
as an interim action level. The contamination in the central
Florida area was most likely due to citrus buffer zone applications
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62
done by the state agriculture department; the panhandle
contamination was most likely due to EDB soil fumigation of
soybean and/or peanut fields.
The Florida monitoring program is a collaborative effort
between the Departments of Environmental Regulation, Health
and Rehabilitative Services, and Agriculture. They have been
sampling wells within 300 ft. of use sites, and intend to
sample a total of 1000 or more wells. All sampling and
analysis has been done since approximately mid-summer, 1983.
As a result of this monitoring program, on September 16 the
State of Florida temporarily suspended the soil fumigation
use of EDB.
c. Georgia
EPA scientists were notified in June, 1982, by EDB
registrants that three wells were contaminated with EDB at
levels as high as 100 ppb (an irrigation well) in Seminole
County. After the registrants failed to conduct any further
monitoring, the EPA and the USGS, in cooperation with the
county extension agent, initiated and completed a reconnaisance
study of the area in late summer, 1983. Nineteen wells and
one surface water sample were analyzed, and six wells were
found to be contaminated with between 0.03 and 11.8 ppb EDB.
In addition, soil cores from one hole drilled to. the producing
aquifer contained EDB below 20 feet. The pesticide was
known to be used throughout most of the study site; apparently,
the uses began after EPA suspended DBCP use in the fall of 1979,
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63
The report (Jovanovich and Cohen) is in review. Conclusions
in this report are that the contamination did not result
from a single point source and was due to agriucultural use
of EDB.
d. Hawaii
Based on the preliminary results from California, in June,
1983, the Agency requested that the State of Hawaii monitor
soil and ground water for EDB. Staff from the Departments
of Health and Agriculture, Castle and Cooke (Dole), and others,
immediately began an active monitoring program (Wong, et
al., in progress).
As of September 1983, most, if not all, community water
supplies within one half mile of EDB use sites have been
sampled and analyzed for EDB contamination. Thus over 100
different drinking water wells have been analyzed for EDB
between June and September. To date, one site has contained
EDB contaminated ground water - the four wells in the Waipahu
well field in south cental Oahu. The levels in all four
wells range between 0.02 and 0.10 ppb. EDB has been used on
pineapple fields near the Waipahu wells.
Soil cores were taken from five Oahu pineapple fields
from depths as great as 60 feet. Three holes were drilled in
each field, for a total of 15 holes. EPA has received partial
data on at least 9 of those holes. The data analyzed thus far
show that EDB is present in soil cores down to the 20 to 30
ft. range. However, a closer examination of the data indicates
that the soil core samples were most likely contaminated
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64
during drilling. EPA scientists cannot say with certainty
what portion of the positive results was due to slow leaching
through the soil profile or what protion was due to contamina-
tion during the drilling process. However, it is likely
that accidental contamination was a significant contributing
factor. Thus the soil core results neither support nor
refute the hypothesis that the four wells were contaminated
through soil fumigation and leaching to ground water. A
brief description of south central Oahu's volcanic soil
follows, along with a concluding statement about the problem.
Most of the organic matter, which tends to bind neutral
organic compounds such as EDB, is confined to the top few
feet of soil, with a heavy amount of clay (ca. 80%) through-
out much of the soil profile (Green, 1983). The flow rate
of water through the top few feet can increase significantly
during a rainstorm, and is relatively fast, while the under-
lying inert clays and saprolite have slower, steadier hydraulic
conductivity (Green, 1983; Eyre, 1983). This material between
the fresh basalt and the top soil has been found to have
practically zero adsorptive capacity for DBCP and certain
herbicides (Green, 1983).
Based on this description and the persistence and
transport discussion below, a picture emerges of the probable
fate of EDB in a typical volcanic soil. Within several weeks
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65
of application, the pesticide leaches down into and diffuses
throughout the top couple of feet of soil. During and after
this time, degradation may occur, to a possibly significant
extent. There is likely a significant amount of sorption
to the soil, which is decreased during and/or after a rainfall
event. This region of EDB sorption could serve as a "reservoir1
of EDB which could then leach in low and nonsteady amounts
into and through the underlying low organic clays, saprolite,
and fissured basalt. Little if any sorption would occur in
this zone. Therefore, no "reservoirs' of EDB could be built
up (as in the top soil) and the EDB would be present in the
water phase. From this point, leaching to the aquifer could
occur quickly with significant dilution occurring along the
way. Therefore intermittent contamination of Oahu's basalt
aquifer will likely occur in unpredictable, although probably
low concentrations if continued EDB use is allowed. The
term "low" in this context means concentrations not exceeding
a couple of hundred parts per trillion.
2. Environmental Persistence and Transport Studies
EDB has a water solubility of approximately 4500 ppm and
a room temperature vapor pressure of 11 torr. Thus it would
tend to be mobile in both air and water. It diffuses in
soils (Thomason and McKenry, 1974) and does not appear to
sorb well to soils relative to other neutral organic chemicals
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66
(e.g., Chiou, et al., 1979). Therefore EDB is very mobile
in the subsurface environment.
Not much is known aDout EDB's persistence, but the Agency
expects it to be stable to photolysis in sunlight. EPA
recently began a hydrolysis study (Jungclauss, et al., in
progress). Preliminary indications are that its half-life
at 20°C (a likely ground water temperature in a southern
climate) is greater than one year under neutral conditions*
and it may be as long as a couple of dozen years. The study
should be completed in November, 1983. Cohen, et al. (1983)
have stated that one of the criteria for determining that a
pesticide may be a potential ground water contaminant is a
hydrolysis half-life of greater than ca. 6 months; thus EDB
meets this criterion.
There are two indications that EDB can degrade in soils.
Castro and Belser (1968) demonstrated that EDB was degraded
to ethylene and bromide ions under optimal conditions in a
California agricultural soil. However, even in the same
soil, the halflives in different experiments varied tremendously
* A likely hydrolysis product is vinyl bromide, a possible
carcinogen.
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67
from ca. 2 weeks to ca. 18 weeks. According to Cohen, et.
al., (1983) the soil half-life criterion for potential ground
water contamination is a half-life of greater than ca. 2-3
weeks. Thus EDB meets this criterion as well. Also, high
levels of bromide ions have been detected in the perch water
aquifer under the site of a several hundred gallon EDB spill in
1977 on Oahu (Mink, 1981). This indicates breakdown of EDB
to an unknown extent in a three year period.
3. Leakage from Underground Fuel Tanks
Underground fuel storage tanks are known to leak, and
this leakage can be predicted (Rogers, 1983). EDB has been
used for several decades as a lead scavenger in gasoline and
aviation fuel. EDB constitutes approximately 0.03% by weight
of leaded gasoline, assuming 1.1 gm lead/gallon of gas, and
17.86% and 63% are the percentages of EDB and tetraethyl
lead in the tetraethyl lead mixture, respectively. Thus,
there is some possibility that EDB could contaminate ground
water through leakage of underground fuel storage tanks.
418-574 0-83-6
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68
This potential for EDB to contaminate ground water from
gasoline losses should be examined on a relative basis. The
Agency estimates that over 20 million pounds of the pesticide
EDB are applied to soil in the U.S. annually. To have an
equivalent loading to soil from losses of gasoline there
would have to be approximately 10 billion gallons lost
directly to the soil every year. This rough calculation
is an overestimate which ignores surface and subsurface
attenuation of EDB. However, even if the EDB applied to the
surface were attenuated 10 times as much as the EDB which could
leak from subsurface gasoline storage tanks, the equivalent
loading to the soil would still require a nationwide annual
leakage of 1 billion gallons of gasoline.
Although gasoline is one of the more frequently reported
contaminants of wells, EPA has not seen any data so far which
demonstrates that the contamination described in section 1
above was due to this phenomenon. EPA scientists would
expect that any wells contaminated by this mechanism would
also contain ethylene dichloride (EDC), which is also a lead
scavenger in gasoline (Johns, 1976). Thus EDC would be a
good chemical marker for this contamination source.
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69
F. Dietary Cancer Risk Equation
The CAG has revised the estimates of cancer risks associated
with EDB residues in the diet. This revision was made to
utilize all of the information collected in the experiment,
particularly the effect for partial lifetime exposure at a
given dose (Weisburger, 1977). The model developed by the
CAG is essentially the one-hit model with "Weibull" timing
(CAG, 1982). This model fits the observed data well, it is
consistent with the biological hypothesis of direct acting
genotoxic agents, and it permits a direct estimate of the
effect of partial lifetime exposure to be made. The model
takes the form:
P(t,d) = l-e~x
where: x = (1.02 x 10~13) x d x Wm1/3[(t-s)7'6-(t-f)7•6]
wm = average weight of the individual from age
f to s (in kg)
s = age at start of exposure (years)
f = age at end of exposure (years)
d = mg/kg/day exposure from age s to f
t = age at end of observation period (years).
For a lifetime exposure, Wm = 60kg., s = 0, f = t = 70 yrs.
of age, the above equation has the form P(d) = 1 -e'^ld^
It should be noted that this lifetime risk equation is
different from the risk equation used for the PD 2/3.
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70
G. Dietary Cancer Risks
1) Dietary Risks to the Average Consumer
The dietary burdens (DB) for EDB uses and the cancer risks for
the average consumer estimated in PD 2/3 are reproduced in
Table 11. The dietary burden for soil incorporation (food
only, not from leaching into ground water) remains the same
as PD 2/3 with the resultant risk being different due to the
use of a different and improved model to estimate risk. The
estimate of bulk grain dietary burden has been increased
significantly (for discussion of dietary burdens see Section
D) , and therefore, the risks for the average U.S. consumer
from this use also increases significantly. The estimate
for additional cancer risk die to bulk grain fumigation is
now 3.3 x 10~3. This estimated risk from the bulk grain
use constitutes a majority (approximate 85%) of the known
dietary risks from EDB.
The spot use of EDB on grain milling machinery has been
estimated to have the same time-weighted average EDB residues
(from treatment to treatment) in wheat flour and baked wheat
products as in PD 2/3. The cancer risk estimate for spot
fumigation has been increased to 2.4 x 10~4. States not
reguiring guarantine EDB fumigations still have contributions
from EDB-treated imported fruit, e.g. from Mexico. It was
assumed these imported fruits could be uniformly distributed for
fresh market consumption throughout the U.S. The tropical fruit.
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71
are assumed to be 100% treated, and distributed throughout
the U.S. The dietary burden for tropical fruit is also
estimated (Table 11, footnote 3). Both of these contributions
of EDB are less than those in states (e.g. California),
which do require quarantine fumigation of fruit from Florida.
It is estimated that the risk to an average individual (60
kg, consuming 1.5 kg food/day) in those states requiring EDB
quarantine fumigation would be 2.4 x 10~~4 from fresh citrus
consumption.
The drinking water cancer risk are summarized in the
following section (Section H).
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Table 11. Comparison of the FD 2/3 and FO I 4 Dietary Burdens and Cancer Risks from ED3
to the Average U.S. Consumer
Fumigation
Use
EDB FD 2/3 ECB Lifetime
Dietary Burden Cancer Risk
(mg.EDB/kg. b.w./day) (FD 2/3)
EDB PD 4 EDB Lifetime
Dietary Burden Cancer Risk V
(mg.EDB/kg. b.w./day) (PD 4)
1. Soil Incorporation - 2.60 x lO"7 5.6 x 10~5 2.60 x 10~7 V 1.1 x KT5
2. Vfrieat Grain
(bulk fumigation)
1.81 x 10~7 2.6 x 10~6
8.00 x 10~5 2/ 3.3 x ID'3
3. Spot (wheat grain -
milling machinery)
3.29 x 10-6
5.1 x 10-5 5.80 x 10~6 5/ 2.4 x 10~4
4. Fruit (quarantine
fumigation, bulk)
in states not
requiring fumigation
citrus -
tropical -
4.11 x 10-7
4.25 x KT6 V
1.7 x 10-5
1.7 x 10~4
-3
CO
in states
requiring fumigation
citrus -
in entire U.S.
population
citrus - 1.09 x 10~5
tropical - 1.70 x 10~6
2.1 x lO-
3.2 x 10-5
6.8 x 10-6
(See table 8 & 9)
2.8 x
Footnotes to Table 11 on next page
-------
Footnotes for Table 11
(1) No residues found at a detection limit of 1 ppb EDB. Assumption that EDB residues can occur at 1 ppb.
CB = (1 x 10"9, residue level) x (1.5 x 106 mg food consumed/day) x ( 0.1038, food factor for wheat) x
(1/60 kg, body weight for "average U.S. consuner") = 2.6 x 10~6 mg/kg/day.
(2) Dietary burden increased significantly from the PD 2/3 (Table 22, Probable Case Estimates of DB)
See text for rationale for estimating EDB dietary burdens in PD 4 in accordance with the Realistic worst
Case proposed in the report by J. Holder, 2/27/80.
(3) Dietary burden for a "tropical fruit eater": DB = 12 fruits/yr x 1 yr/365 days x 0.25 kg /fruit x
0.031 mg EDB/kg fruit x 1/60 kg body weight. Assumed a rate of 12 fruits/yr and an average between
a papaya and a mangoe is 0.25 kg/fruit.
(4) Lifetime risks for an average person (eats 1500 g food/day and weighs 60 kg ) for a lifetime of ex-
posure and observation for cancer were calculated by the equation P = 1 - e~41d where d = dose =
exposure in mg EDB/kg/day
(5) The esimated spot contribution has been changed from the probable estimate (3.2 x 10~6) to the realistic
worst case (7.6 x 10 ~6) which is estimated in the J. Holder report dated 2/27/80. This realistic
worst case has been adjusted by 3/4 in accordance with the most recent use information in Chapter IV, PD 4.
The adjustment ( 0.75 x 7.6 x 10~6) makes the dietary burden estimate for spot = 5.8 x 10~6 mg/kg/day.
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74
2.) Dietary Burdens from EDB at Various Ages and Age-Related
Variation in Risks to BOB due to one Year of Additional EPS
Exposure
The estimated dietary burdens (DB) at ages of 2, 16, 30, and 50
years are presented in Table 12 with assumptions and example
calculations presented in the footnotes. The total DB (and DB
from each fumigation use) decreases with age (i.e., the DB is
highest for the young*)
The estimates of dietary burdens in Table 12 are used to calculate
estimates of cancer risks for one-year of additional exposure to
EDB with observation for cancer for the rest of a normal (70
years) lifetime. It can be seen in Table 13 that these incremental
risks decrease with age. Males were used for the calculation in
Table 13. Female risks are approximately 20% less than the male
risks.
* These age-specific estimated dietary burdens reflect the variation
with age of body weights and daily food consumption (both in
total grams/day and in percentage of each type of food consumed
per day). The later, variation of food factors with age, are
not known at this time, but are being estimated by the Agency
at this time and will be available at a later time
(Chaisson, EPA).
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Table 12: Dietary Burdens (DB) Resulting from ECB Fumigation Uses
(Age Specific Estimates)
(mg EfB/kg/day)
Fumigation Use
Soil Incorporation
(food only)
Grain (wheat, bulk fumigation)
Spot (grain milling machinery)
Fruit Quarantine
( in states not requiring fumigation)
citrus-
tropical-
Fruit Quarantine
( in states requiring citrus
fumigation)
Estimated
2 years old
8.84 x 10-7
2.61 x 10-4
8.38 x IIT6
1.40 x 10~6
negligible
1.44 x 10~5
Dietary Burdens
from EDB
16 years old
3.91 x
1.21 x
3.70 x
6.17 x
4.18 x
8.64 x
10
10-4
10-6
10-7
10-6
i
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Footnotes for Table 12
1. Dietary Burdens (CB) are at the ages indicated and are calculated in PD 2/3 for 60 kg individual eating
1500 grams food day. CB's presented in PD 2/3 for 60 kg individual eating 1500 grains food/day. CB's
presented in Table were converted to EB's here for different age groups by mulitplying by the appropriate
correction factors for different food consumption and weight. For instance, for a two-year old male
weighing 14*&-kg and eating 1232g/day:
soil fumigation DB Soil Fumigation CB
(in PD 2/3) conversion factors (PD 4)
2.6 x 1CT7 mg/kg/day x 60 kg x 1232 g /day = 8.84 x 10~7 mg/kg/day
1500 g/day 14.5 kg
"average person"
weighing 60 kg, eating 1500g./day CB for 2 yr. old
This type of conversion was applied to soil incorporation, spot, and citrus quarantine fumigation
uses where the contamination levels (in ppb of ED3) were reconsidered to be the same as in PD 2/3 and
are carried over here (in Table 12) in the PD 4 for different age-group consumers.
Data used in the conversions:
2 yr old 16 yr old 30 yr old 50 yr old
body weight (kgs.) - 14.5 60.94 73 77
daily food consumption - 1232 2288 2208 2250
(grams/day)
conversion factors - 3.398 1.502 1.227 1.169
Female consumption and body weights accounted for a 20% (approx.) decrease in DB, and thus a 20%
decrease in the female risks. The examples shown in Table 12 are based on male body weight
and food consumption.
2. Bulk wheat grain fumigation was re-estimated to be higher than in the PD 2/3 estimate of 0.07 ppb
and is now estimated to be 31 ppb ED3 (see text for rationale).
The DB is calculated here is for a 16 yr. old male, assuming 100% of the commodity is contaminated
at the 31 ppb level, and wheat products are 10.36% of the diet.
D3 = 31xlO~9 x 2288 g/day x 1000 mg/g x 0.1036 = 1.206 x 10~4 mg ECB/kg bw/day
60.94 kg body weight
-------
Footnotes for Table 12 (Cont'd)
3. The dietary burden for a "tropical food eater" is used for the quarantine use of EDB on tropical
fruit to to be shipped to the continental U.S.
It was assimed that a reasonable level of consumption is 12 tropical fruits per year.
Thus, the DB can be calculated, for a 16 yr. old male in the U.S.:
DB = 12 fruits/yr x 1 yr/365days x 0.25 kg /fruit x 0.031 mg EDB/kg fruit
60.94 kg body weight for a 16 yr old male
where 0.25 kg is the average weight of papayas and managers and mangos on per
fruit basis 0.031 mg EDB/kg fruit = 31 ppb ECB average contmination level
12 fruits/yr. is assumed for the 16, 30, and 50 yr. old people and 2 year
old children were assumed to eat negligible amounts of tropical fruit.
4. The total DB's frcm each use are summed from the Agency's current understanding of probable
ECB contaminating sources. Sources of possible contamination include meat and
milk. Meat and milk could be contaminated by livestock being fed on the farm, or in
fattening feedlots, ECB contaminated grains. The Agency does not have data on these
conodities, nor can any reasonable estimates be made at this time due to a lack of information.
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Table 13: Incremental Risks from One Year o£ Additional
Dietary Exposure to BOB at Various Ages with Observation for Cancer for a Lifetime £/
Fumigation Use
Soil Fumigation -
(food only)
Wheat Grain -
(bulk)
Spot (Fumigation
milling machinery)-
Fruit Quarantine
( in states not
requiring fumigation
Citrus -
Tropical -
Fruit Quarantine
( in states requiring
fumigation)
citrus -
Beginning and Ending Age of One Year of Additional
2 to 3 yrs. old 16 to 17 yrs. old 30 to 31 yrs. old
2.0 x KT6 3.0 x 10~7 3.5 x 10~8
5.8 x 10~4 9.4 x 10~5 1.0 x 10~5
1.9 x KT4 2.9 x 10~6 3.3 x KT7
3.1 x 10~6 4.8 x 10-7 5.6 x 10~8
negligable 3.3 x 10~6 3.9 x lO"7
3.2 x 10~5 6.7 x UT6 7.8 x Kr7
Exposure to ECB
50 to 51 yrs. old
3.3 x 10-10
9.7 x 10-8
3.1 x 10~9
5.2 x 10-10
3.6 x 10-9
7.3 x 10~9
-3
00
1.) The risk model used was that described in IV F. Risks for women were ..- ,U:d to be approximately 20% less
than males because of differences in dietary burden. Male risks are present. . u this table.
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79
H. Ground Water Cancer Risk
The model, discussed in Section III F, was used to estimate
the cancer risks below.
The detection limits for EDB vary in different laboratories
between 0.02 parts per billion (ppb) and 0.10 ppb. Therefore,
the Agency has included these detection limits in Table 14
below, in addition to other observed contamination levels.
Table 14. Cancer Risks for EDB Ground Water
Contamination
Concentration
0.02
0.1
1.0
5.0
100
ppb
ppb
ppb
ppb
Lifetime Cancer
3 x 10-5
1.5 x 10-4
1.5 x 10-3
7.5 x 10-3
1.5 x 10-1
Risk*
* EPA assumes consumption of 2 liters of water per day for an
adult, a 60 kg lifetime average weight, and a 70 year lifetime,
This 2 liter assumption includes water consumed per se,
as well as water used in reconstituting powdered drinks, etc.
Cancer risks, as presented in this table, are the additional
risks estimated for a lifetime of exposure.
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IV. Analysis of PD 2/3 Comments and Revisions Relating t.o Benefits
Detailed analyses of the benefits derived from registered uses of
EDB are presented in the PD 2/3. Benefit analyses for the major
soil nematicide sites have been substantially revised since
issuance of the PD 2/3. The following discussion is a summary
of the results of the updated analyses, as well as a summary
of comments which were received in response to the PD 2/3
addressing the benefits derived from the use of EDB and the
Agency's response to these comments.
1. Preplant Soil Fumigation
Ethylene dibromide is applied as a soil fumigant on numerous
agricultural crops for nematode control. Use as a soil fumigant
accounted for over 90 percent of the total pesticidal use of
EDB in 1978. Since 1978 use of EDB as a soil fumigant has
increased significantly. In 1978, the Agency estimated that
cancellation of this use could result in adverse economic
impacts of over $20.5 million annually (1978 nominal dollars).
The 1983 analysis estimated that cancellation would result in
adverse economic impacts at the user level from $26.4-$42.8
million (1983 nominal dollars) annually with additional effects
at the market and consumer level.
When the original benefit analyses, used as input to the EDB PD
2/3 were made, the soil nematicide market was unstable due to
regulatory action anticipated on dibromochloropropane (DBCP).
The PD 2/3 benefits analyses incorporated assumptions which
were subject to uncertainty concerning how EDB would be used
in the absence of DBCP. In addition, since issuance of the PD
2/3, EDB was registered.for use as a soil nematicide on soybeans.
This registration now accounts for approximately half of total
EDB pesticidal use.
80
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81
Due to new concerns over EDB contamination of groundwater and
substantive changes in EDB's soil nematicide market since the
PD 2/3, new benefit analyses on the major soil nematicide sites
were conducted during the summer of 1983. The analyses were
undertaken to identify the locations and volumes of the current
use of EDB as a soil nematicide, and to assess the current
(1983) benefits of this use. New benefit analyses were completed
for soybeans, California vegetables, cotton, peanuts, tobacco,
sweet potatoes, white potatoes, and pineapples. The results
of these analyses are summarized in Table 15.
Currently, approximately 1.0 million acres are treated for
nematode control with nearly 23 million pounds of EDB active
ingredient annually. The major use sites are soybeans (12.8
million pounds active ingredient), cotton (4.5 million pounds
active ingredient), and peanuts (2.2 million pounds active
ingredient) with lesser volumes applied to other crops. Most
of the use is located in the southeastern United States.
Soybean, peanut, and pineapple growers are expected to experience
the largest economic impacts. Aggregate annual impacts at the
user level range from $26.4-$42.8 million annually dependent in
the selection and efficacy of available alternatives. The primary
substitutes for EDB soil nematicide formulations are expected to
be D-D, Telone®, Nemacur®, Mocap®, Furadan®, and Temik®.
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Table 15. Annual Economic Impacts of the Cancellation of EC8 As a Soil Nematicide on
Major Use Sites
Economic Impacts
Crops
Soybeans
California
Vegetables I/
Tomatoes
Beans^/
Carrots
Other produce
(melon,
watermelon.
squash, bell
peppers, as-
paragus, head
lettuce, cucumber
peas, cauliflower
pimpkin, parsnip)
Acres Treated
000 's acres
532.8
8.7
11.4
3.7
2.3
Active Ingredient
000 's pounds
12,787.0
177.3
173.6
68.2
70.5
User
User impacts of $7.0 million
due change in control costs.
Price of soybean oil may
increase by $0.01-30.03 per
pound. No loss in production
is anticipated.
User impacts resulting from
increased nematode control
costs. No loss in production
anticipated.
Increased control costs of
alternatives range from
$0.3-$1.1 million
Increased control costs of
alternatives range from $0.5-
$1.5 million
Increased control costs of
alternatives range from
$0.5-$1.5 million
Increased control costs of
alternatives range from
$0.1-$0.3 million
Market Consumer
Welfare losses to
consumers of about $7
million in second year
after cancellation, with
decreasing losses in
later years (declining
to $0 in 5-7 years) .
Increased production
costs may cause some
users to grow different
crops. Consumer impacts
would be negligible.
oo
CO
I/ ECB use was recently suspended by CDFA in the countries of Fresno, Kern, Merced and Stanislaus.
These counties apply a significant proportion of the EEB used in California. The decrease is
not reflected in the estimates given in this table.
2/ Represents use on both green lima beans and dry lima beans.
-------
.c.
O>
I
Ul
Table 15. Annual Economic Impacts of the Cancellation of EDB As a Soil Nematicide on
Major Use Sites (Cont'd)
Crops
Cotton
Peanuts
Tobacco
(flue-cured)
Sweet Potatoes
White Potatoes
Acres Treated
000's acres
185.0
134.5
68.1
9.1
22.5
Active Ingredient
OOP's pound
4,500.0
2,151.8
913.6
160.2-236.4
960.0-1080.0
Economic Impacts
User
S3.0 million user impacts.
Primarily southeast region.
Impacts result from increased
production costs. No loss
in production is anticipated.
Change in control costs of $4.1
million. Change in value of
production of S3.8 million due
to planting delay and reduced
efficacy.
Aggregate increase in treatment
cost $2.02 million. No loss
in production anticipated.
$0.3-$0.5 million user impacts
resulting from increased control
costs. No loss in production
anticipated.
User impacts from increased
control costs $1.6-$2.2
million. No loss in
production anticipated.
Market/Consumer
An additional cost for
nematode control could
cause growers to change
crops. This would most
likely occur in the south-
east region. Negligible
consumer impacts.
None.
None.
None.
Negligible.
00
oo
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Table 15. Annual Economic Impacts of the Cancellation of EDB As a Soil Nematicide on
Major Use Sites (Cont'd)
Economic Impacts
Crops
Pineapples
Total
Acres Treated
000's acres
4.0
982.1
Active Ingredient
000's pound
810.0
22,772,2-22,968.4
User
Assuming newly
registered alternative
is efficacious, user
impacts will range from
$3.6-85.0 million
annually in increased
nematode control
costs and losses in value
of production. In
addition, up front
capital investiments
of $3.2-$6.9 million
will be necessitated.
If newly registered alternative
is not efficacious, user impacts
of $15.8 million annually in
increased nematode control
costs and losses in value
of production are anticipated.
In either case, since pineapple
companies are vertically in-
tegrated, additional losses
in profit may be incurred
at processing and marketing
levels due to reduced production
and increased average costs per
unit.
Market/Consumer
Due to the oligopolistic
nature of pineapple
industry, any market/
consumer impacts
cannot be quantified;
however, substantial
losses in production
could result in prices
increases at the consumer
level, if alternative are
not adequately effective.
CO
$26.4-$42.8 million in increased
nematode control costs and
losses in value of production.
At $26.4 million, capital
investments of $6.9 million
would be incurred by pineapple
growers.
Sources: See Additions to Bibliography (Economics)
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85
The cancellation of EDB for use on soybeans would result in
increased nematode control costs of $7.0 million annually for
soybean growers. The 1981 value of U.S. soybean production was
approximately $13 billion. Cancellation of EDB for use on peanuts
would result in increases in control costs of $4.1 million and
reduced value of production estimated at $3.8 million annually.
1981 value of U.S. peanut production was approximately $1.0
billion.
Data submitted to the Agency indicates that the magnitude of
the economic impacts are most likely dependent on the efficacy
of Nemacur®, a newly registered systemic nematicide. if Nemacur®
performs adequately, pineapple growers would experience annual
losses due to increased nematode control costs and losses in
value of production of $3.6-$5.0 million annually while incurring
capital costs of $3.2-$6.9 million. If Nemacur® is not
efficacious, economic impacts could increase to $15.8 million
annually in losses in value of production and increased nematode
control costs. These impacts are large relative to the value
of pineapple production; 1981 value of Hawaiian pineapple
production was estimated at approximately $90 million.
Telone II®, a preplant chisel injected nematicide, can be
applied to Hawaii pineapple for control of the root-knot
nematode, Meloidogyne javanica (Treub). EDB is applied for
control of the reniform nematodes, Rotylenchulus reniformis
(Linford). If Telone II®, without Nemacur®, provided nematode
control equivalent to EDB, growers would experience increased
nematode control costs of approximately $0.5 million annually.
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86
However, EPA has not received documentation that Telone II®
alone can achieve comparable efficacy to EDB.
2• Stored Grain Fumigation
The conclusions reached following the benefits analysis of EDB
fumigation of stored grain in the PD 2/3 concluded that alternatives
were available. EDB for this use would probably be replaced by
the carbon tetrachloride/carbon disulfide (CT/CD) and/or aluminum
phosphide. Other potential alternatives were identified but are
not anticipated to capture a significant portion of the liquid
grain fumigant market in the near future. Carbon dioxide has since
been registered for this use,
Hopes Consulting, Inc. (Hopes) submitted a detailed evaluation
(Comment #26) of the benefits derived from the use of EDB to
control insect pests of stored grain. Additional information
was also provided by the Douglas Chemical Co. (Douglas) and
by the U.S. Department of Agriculture (USDA). The comments
and additional information are discussed topically.
a. Revised Estimate of Rate and Frequency of Application
Using methodology similar to that used in the Agency's
Preliminary Benefit Analysis, Hopes estimated the economic
impact of cancelling EDB. Hopes estimated an increase in
user costs of more than $56 million as compared to the
Agency's estimate of a possible slight decrease in user
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87
costs. Differences in rates and frequencies of application
assumed in the PD 2/3 and by Hopes account for the large
variance in estimated user impact. The Agency's calculations
were based on rates and frequencies of application from
product label data and State and Federal pesticide use
recommendations for EDB and CT/CD. Hopes used an application
rate for CT/CD which is double that of EDB and also estimated
that CT/CD would be used twice as often as EDB (e.g., four
times annually versus twice annually for EDB). Douglas, a
major producer and distributor, indicated that currently, only
one annual EDB treatment occurs at a typical rate of about 2
gal/1000 bushels of grain. These data more closely approximate
the Agency's original estimates and indicate that usage
rates for EDB may have declined slightly. The Agency believes
that the Douglas data approximate current label information
and are more indicative of current use than are the Hopes data.
b. Additional Estimates of Volume for Grain Fumigation
Hopes estimated approximately 4.56 million gallons of EDB
formulations were used to treat stored grain. The Agency
estimated approximately 1 million gallons were used. The
USDA provided preliminary results of a study titled "An
Interim Analysis of EDB Use in On-Farm Storage." This
analysis indicates 57,492 pounds of EDB were used on farms.
Douglas estimated on-farm use of the active ingredient EDB,
to be 202,000 pounds in 1981 and that liquid grain fumigants
containing EDB approximates 375,000 to 425,000 gallons annually,
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c. Conclusions On Stored Grain Fumigation Use
Based on available use recommendations and label data, the
Agency believes that Hopes has overestimated the rate and
frequency of applications of both EDB and CT/CD. As a result
of overestimated usage, Hopes has also overestimated the
benefits attributed to EDB usage.
The Agency believes current usage of EDB and CT/CD is probably
less than typical usage levels in the mid to late 1970's when
the PD 2/3 benefit analysis was conducted.
3. Spot Fumigation of Grain Milling Machinery
EDB has been used for more than 20 years as a spot fumigant to
control insect pests that infest flour milling equipment. The
only alternative spot fumigant is a mixture of 75 percent
ethylene dichloride and 25 percent carbon tetrachloride; however,
the dosage required for this pesticide is so large that the
milling industry does not consider it to be a viable broad scale
alternative. The overall results of using this substitute
include the application of a much greater quantity of pesticide,
a higher cost for fumigation, greater labor costs, and more
down time for the mill.
The Agency also determined that the most likely alternative to
EDB for spot fumigation is general fumigation of the entire mill
spaces. Methyl bromide (MB) and aluminum phosphide (AlP) are
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89
currently the two most commonly used general space fumigants. The
Agency projected in the PD 2/3 that at least 3-5 additional general
fumigations per year would be required to obtain control. Based
on a comparison of current practices versus the use of alternatives,
the PD 2/3 indicated an increase in costs of $2.9 to $6.0 million
annually for use of 3 and 5 additional general space fumigations
respectively. The Agency has received numerous comments
regarding the viability, efficacy, and costs of alternatives
to EDB for controlling insects which infest flour milling
machinery. Commenters provided substantive data for four
broad issues: a) EDB alternatives and their efficacy, b) EDB
usage estimates, c) frequency of application, and d) EDB spot
treatment costs versus the costs of general fumigation. The
comments are discussed below and analyzed in detail in a separate
document titled "Analysis of Comments on Proposed Action on
EDB Use in Spot Fumigation of Milling Equipment" (Holtorf and
Ludvik, 1982).
a. Efficacy of Alternatives
The Agency's assessment of the efficacy of methyl bromide
(MB) or aluminum phosphide (AlP) as alternatives to EDB was
questioned by Ferguson Fumigants Inc. (Comment #22) and by
USDA. Ferguson argued that neither MB nor AlP are pupacidal
and that only EDB alone is efficacious in controlling tolerant
life stages such as the egg and especially the pupal stage.
However, the Agency is aware of a number of studies which
present data that demonstrate the pupacidal activity of MB or
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90
AlP. These studies include: Kazmaier and Fuller (1959),
Krohne and Lindgren (1958), Lindgren et al., (1958), and
Munro (1969). The Kazmaier and Fuller study also indicates MB
and AlP are ovacidal (effective against egg stage). Therefore,
the Agency rejects the contention that EDB is the only efficacious
compound for controlling all life stages.
b. Usage Estimates
Ferguson Fumigants Inc., the Miller's National Federation, and
the USDA all submitted data which indicate that the overall
quantity of EDB usage in spot fumigation may be less than that
estimated by the Agency in the PD 2/3. The analysis of benefits
presented in PD 2/3 was based on the assumption that
all mills used EDB spot treatments. Although the usage
estimates provided by the commenters were not consistent, the
new data indicate that approximately 75 percent of the wheat
flour milled in the U.S. is produced in mills treated with
EDB.
Because the Agency's original assessment was incorrect, the
overall benefits of EDB use in flour milling are less than
were estimated in the PD 2/3. Consequently, because fewer
mills than previously estimated use EDB, the relative costs of
substituting general space fumigation for spot treatments were
also overestimated in the PD 2/3.
c. Frequency of Application
The single, most often discussed issue is that of the frequency
of general fumigations necessary to maintain insect control.
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91
Most comments indicated that 4 or 5 general fumigations would
not be adequate to maintain effective control. Commenters
stated that general fumigation would have to be practiced
on the same schedule as spot fumigation or about 12 to 14
fumigations annually. One commenter (Comment #44) indicated
that general fumigation may be practiced 8-10 times annually.
It was indicated in the preliminary benefit analysis, however,
that frequent (i.e. 12-14 per year) general fumigations would
be prohibitively expensive, and that the industry would probably
adopt a strategy which would utilize fewer general fumigations.
The Agency received comments that even 4 or 5 general fumigations
would be prohibitively expensive (Comment #43), and that general
fumigation would not be conducted even 4 or 5 times per year
to replace spot fumigation (Comment #1A). Though arguing
that 4 or 5 general space fumigations would not substitute for
spot fumigations, the commenters did not provide the Agency
with data to support their claim that general fumigation is
ineffective.
The Miller's National Federation (MNF) surveyed 27 member firms
which produce approximately 80% of the wheat flour milled in
the United States (Henwood, 1982). Their survey, in addition
to a previous MNF survey on total usage of EDB, provides the
most definitive source of information available regarding the
frequency of application of EDB in the milling industry. The
Henwood study indicates that, of the mills surveyed, those
treated with EDB produce about 75% of the daily capacity of the
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92
industry and that each mill is treated with EDB an average of
about 10 times per year.
In summary, the comments submitted to the Agency indicating
that current usage of EDB for spot fumigation is less than
estimated in PD 2/3; that EDB is used less frequently than
indicated in PD 2/3; and that the amount of flour exposed to
treatment is less than indicated in the PD 2/3. The Agency
recognizes that general fumigations will require more diligence
in regard to sealing mills and maintaining duration of exposure
to obtain control of insect pests in flour mills. The Agency
does not believe that the milling industry will be required to make
12-14 general space fumigations annually rather than 4-6 general
fumigations as indicated in the preliminary analysis. The Agency
has concluded that the information submitted by commenters does
not adequately support their contention that alternatives to
EDB would not be used, or the Agency's preliminary benefits
analysis failed to consider appropriate facts.
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93
d. Treatment Costs
Three respondents provided mill-specific information on
comparative costs of spot vs. general fumigation in their
mills. The Ohio Department of Agriculture (Comment #14) noted
that the cost of a complete general mill fumigation is about
$5,400 compared to a spot fumigation cost of $600. These costs
did not include the charge for "down time".
The Hawaiian Flour Mills, Inc., (HFM) (Comment #29) provided a
detailed breakdown of the costs of general and spot fumigation.
HFM indicated that their fumigation costs would increase from
$8,774 annually using EDB to $24,079 annually for general
fumigations using aluminum phosphide and in addiiton they
would lose of 4 to 5 production days per year. HFM did not
provide data regarding the frequency that EDB was currently
being used in their mills nor were data submitted on how
frequently general fumigation or other controls would be used
if EDB were cancelled. North Dakota Mills and Elevator (Comment
#27) indicated that each general fumigation costs approximately
$4,800 while each spot fumigation costs approximately $500.
The National Pest Control Association Inc. (NPCA) (Comment #44)
submitted estimates of the impact of cancelling EDB in wheat,
rye, and corn mills. NPCA estimated that use of general mill
fumigation in the wheat and rye milling industry would increase
treatment costs by about $12.8 million annually ($43,000 per mill)
if 8 general fumigations replaced EDB spot fumigations. For corn
mills, NPCA estimated an increase of $2.6 million annually
($28,000 per mill) again, basing their estimates on 8 annual
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94
general fumigations. Ferguson Fumigants, Inc. (Comment #33)
provided a 1978 analysis of the cost of replacing EDB with
general space fumigation. They estimated that the cost to the
milling industry of using methyl bromide would be approximately
$24.1 million annually as compared with about $1 million for
an EDB program. This analysis assumed that general fumigation
would replace spot treatment on a one-to-one basis; therefore,
13.7 general fumigations per year would be required throughout
the entire milling industry.
The NPCA 1981 estimate of $15.4 million (using 8 general
fumigations) is about double the Agency's preliminary 1978
estimate of approximately 7.8 million (using 5 general space
fumigations including the one normally scheduled). The Ferguson
Fumigants Inc. estimate of $24.0 million assumed 13.7 general
fumigations. The NPCA and Ferguson Fumigants estimates appear
to be based on the cost of using general fumigation throughout
the entire milling industry. However, EDB usage is apparently
not as widespread as previously believed and could be 25% to
50% less than was estimated in the PD 2/3 (i.e., 50% to 75% of
the mills use EDB). These estimates of the cost of space
fumigation are therefore overestimated to the extent that they
rely on the assumption that cancellation of EDB would impact
the entire milling industry.
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95
Although data are not available to estimate with precision the
frequency of usage of general fumigation in place of spot
treatments, The NPCA 1981 estimate (based on 8 general fumigations)
of $15.4 million, certainly is not unreasonable and shows relatively
close agreement with the PD 2/3 estimate. Allowing for inflation
of input factors during the 1977 to 1981 period. The estimated
impacts presented in the PD 2/3 would be higher and could be
expected to converge with the NPCA estimates, especially if the
PD 2/3 estimates were recomputed based on 8 general fumigations.
The Agency does not believe that the milling industry, on average,
will adopt a schedule of 13.7 general fumigations as suggested
by Ferguson Fumigants Inc. The high cost and added inconvenience
of general fumigation will force millers to limit the number of
general fumigations to a schedule which is less frequent than
is currently practiced with the spot materials.
e. Conclusions on Spot Fumigation
Comments submitted in response to the PD 2/3 generally agreed
with the Agency's preliminary assessment of benefits that
cancellation of EDB use in spot fumigation will increase the
cost of insect control in the milling industry. The comments
stressed that in comparison to whole mill fumigation (with MB
or AlP), EDB spot treatment is much more convenient, more
effective in certain situations and is much less expensive.
The comments did not provide new data, information, or arguments
which could persuade the Agency to alter its preliminary findings.
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96
4. Quarantine Fumigation of Citrus , Tropical Fruits , and
Miscellaneous Fruits and Vegetables
The U.S. Animal and Plant Health Inspection Service (APHIS)
and the states of Texas, Hawaii, Louisiana, California and
Arizona require the use of EDB in their fruit fly quarantine
programs. Prior to March, 1982, the Japanese government also
required EDB fumigation as the only approved method of treating
all fresh citrus and tropical fruit imported from the U.S. In
PD 2/3, the Agency estimated that major economic impacts would
occur if EDB were cancelled for these uses. Depending on the
acceptability of cold storage and/or irradiation as viable
technological alternatives, the magnitude of adverse economic
impacts may be reduced. Several comments pertaining to the
estimates of benefits were submitted. Most of the comments
claimed an increased need for EDB due to recent infestations
of the Mediterranean and Oriental fruit flies in California.
A second major concern is the viability of gamma irradiation
as an alternative to EDB post-harvest fumigation.
Several commenters (Comments #3, ttlOA, #20) argued that
the 1981 Mediterranean fruit fly infestations in California
have increased the need for, and thus the benefits derived
from the use of EDB fumigation. Due to the uncertainty associated
with predicting the extent and/or intensity of future medfly
infestations, the Agency has not modified the original estimates
of benefits. In March, 1982, the Agency was informed that the
Japanese government has approved the use of cold storage, for
those commodities adaptable to the procedure (oranges and
grapefruit) infested with the Mediterranean fruit fly.
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97
The USDA/APHIS is currently in the process of developing cold
storage procedures for treatment of the Carribean fruit fly
(Helms, Personal Communications, 1982a and b). As of August
1983 experimental data indicated that Carribean fruit fly
eradication is technologically feasible using cold storage for
shipments to Japan (Vlier, personal communication). Although
results indicate technological feasiblity, it is uncertain
whether Japan will accept the cold storage quarantine method
for the Carribean fruit fly.
With regard to interstate citrus shipments and quarantine
regulations, some progress has been made in reducing the need of
EDB treatments to Texas citrus. Over the past 2 harvest seasons
(1981/1982, 1982/1983) APHIS has implemented a Mexican fruit fly
certification program in Texas. The program measures fruit fly
populations and determines whether those populations are low
enough to allow interstate shipment of citrus without quarantine
treatment. Theoretically, the certification program will reduce
the need for quarantine treatment; however, since fly population
levels can increase, not all fruit in all Texas locations and
harvest periods can be certified as pest free. Therefore,
alternative controls for EDB fumigation must be available as
back-up to the certification program to avoid adverse economic
impacts.
The U.S. Department of Agriculture (USDA), the Hawaii Papaya
Industry Association (HPIA), the Hawaii State Department of
Agriculture (HA), and the California Citrus Quality Council
(CCQ) all indicated that they do not consider gamma irradiation
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98
to be a feasible alternative by July of 1983. However, the
Pood and Drug Administration has published an Advance Notice
of Proposed Rulemaking 46 FR, 18992-3) which initiates the
process to establish criteria for evaluating petitions for
irradiated foods. In addition, FDA has authorized the use of
irradiation in emergency situations to control Mediterranean
fruit fly in infested fruit (Hayes, 1981). The Agency has now
extended the phase out of the EDB quarantine use until
September 1, 1984, to provide additional time to implement
alternatives.
The Hawaii Papaya Industry Association (Comment #23) indicated
that approximately 91 percent of the Hawaiian papayas were
marketed as fresh fruit with approximately 74 percent being
shipped to the mainland U.S. and to Japan. The HPIA contends
that a cancellation of EDB, without suitable alternatives,
would totally destroy the Hawaiian papaya industry. The Agency
acknowledges that a lack of acceptable control measures would
have serious negative impacts on the papaya industry. However,
if FDA approves the use of irradiation for papaya and if irradiation
is acceptable to Japan, the economic impacts on the Hawaiian
papaya industry are expected to be less substantial.
The Hawaii State Department of Agriculture indicated that
currently, papayas are grown and fumigated on at least three
different islands and that construction of irradiation facilities
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99
at each location would be economically unsound. The Department
also indicated that a central irradiation facility would increase
shipping costs and drastically increase the amount of handling.
Although the Agency agrees that such circumstances could result
in economic impacts, the State of Hawaii did not submit data
which would allow the Agency to quantify these concerns.
The Agency has further determined that papayas are fumigated
on only two islands, Hawaii and Kauai, and that most of the
fumigation occurs on Hawaii.
The Agency is aware that several commercial enterprises are in
the process of designing and building gamma irradiation facilities
in several locations in California and Florida. In light of
the pending FDA rulemaking and the proposed construction of
gamma irradiation facilities, the Agency believes that gamma
irradiation should be considered as a potential alternative
to EDB fumigation in the future.
The USDA asserted that a cancellation of EDB would weaken the
trade positions with Mexico, Haiti, Israel, and Morocco. USDA
contends that suitable alternatives to EDB are not available
for citrus and tropical fruits originating in these countries.
However, the USDA did not provide data demonstrating that
cancellation of EDB would adversely affect those trade positions
with Mexico, Haiti, Israel, or Morocco. EPA, however,
concludes that these exporting nations will have available the
same alternatives for EDB use as United States growers.
418-574 O - 83 - 8
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100
5. Felled Log Fumigation
In PD 2/3, the Agency estimated 68,000 logs annually in Colorado
and North Dakota were fumigated with EDB to control several
species of bark beetles. When the PD 2/3 Benefits Analysis
was performed, endosulfan and lindane were registered alternatives,
but the Agency did not consider lindane as a viable alternative
due to its status as an RPAR chemical. Although endosulfan was
considered less effective than EDB or lindane, the Agency
concluded its use for bark beetle control could reduce treatment
costs as much as $36,000 annually (1978 nominal dollars).
The Forest Service, Larimer County, Colorado, provided data on
the benefits of using EDB on felled logs. The process, from
felling through treatment, costs $10 to $100 per tree and
cannot be conducted on a scale large enough to effectively
reduce bark beetle populations. In addition, the Forest
Service indicated that control costs in conjunction with adverse
health effects have resulted in a decision to suspend further
use of EDB in bark beetle control projects in Larimer County.
The U.S. Department of Agriculture responded to the PD 2/3 by
noting that endosulfan is not specifically registered to control
the mountain pine beetle and that the Department was not aware
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101
of efficacy data comparing endosulfan with EDB. The USDA
further stated that lindane is actually the compound of choice,
as an alternative to EDB for treatment of the mountain pine beetle,
The Agency did not receive sufficient additional information
that would allow an improved estimate of the benefits derived
from the application of EDB to felled logs. The Agency, however,
is reevaluating its preliminary decision to cancel the use of
lindane on felled logs, and is likely that this preliminary
decision will be reversed. Thus, lindane will probably be
available as an alternative to EDB. In sum, the economic
impacts of an EDB cancellation would be minimal for this use.
6 . Minor Uses
The Agency did not receive substantive data for other uses
of EDB. Therefore, the Agency has no basis to change the
original assessments as contained in PD 2/3. Consequently,
the PD 2/3 estimates of benefits resulting from the following
uses of EDB are not revised: termite control, fumigation of
stored beehive supers and honeycombs, fumigation of stored
clothing, furniture, and quarantined plants, soil and grass sod.
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V. Summary and Conclusions
The Agency has determined that EDB is a potent animal carcinogen,
a mutagen to a variety of plant and animal cells, and is capable
of producing adverse reproductive effects in animals. EDB is
potentially capable of producing these adverse health effects
in humans at measurable levels in the human diet, in the
ambient air of application sites, and in the ambient air of
facilities where treated commodities are handled and stored.
The Agency has carefully weighed the human health risks against
the economic benefits for each use of EDB. The Agency has
determined that no remedial changes can be made in the
registration of EDB for most uses to avoid unreasonable adverse
effects on human health.
The Agency further has determined that continued registra-
tion of EDB as a soil fumigant poses an imminent hazard during
the period in which administrative hearings would delay the
the cancellation of these registrations. Continued use of the
chemical during these hearings would contribute additionally
to an already serious hazard. Emergency suspension is the
only mechanism available to the Agency to cease immediately
the use of a pesticide. The Agency has also determined that
an emergency exists resulting from the soil fumigant use of
EDB such that an emergency order should be issued immediately
suspending these registrations.
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103
The Agency has further determined that the registrations for
use as a soil fumigant, grain fumigant, spot fumigant and
felled log fumigant should all be cancelled. The Agency,
however, has determined that the cancellation of EDB products
used for fumigating citrus, tropical fruit and vegetables
should not be made effective until September 1, 1984, in order
to allow time for alternatives for this use to become available
on a commercial scale. The Agency has decided to continue
registration of EDB products used for the minor uses of
termite control, fumigation of beehive supers and honeycombs,
vault fumigation and Japanese beetle control, only if specified
changes are made on the labels to reduce the risks presented
by these uses.
A summary of the Agency's final regulatory decision on EDB is
presented in Table 16, and the details of the regulatory decision
are presented in the Federal Register Notice announcing the
availability of this document.
TABLE 16—SUMMARY OF FINAL REGULATORY DECISION ON EDB
Soil Fumigation Cancellation effective 30 days
after this Notice; Emergency Sus-
pension effective immediately.
Stored Grain Fumigation Cancellation effective 30 days
after this Notice.
Quarantine Fumigation of Cancellation effective September 1,
Citrus, Tropical Fruits 1984.
and Vegetables
Spot Fumigation of Grain Cancellation effective 30 days
Milling Machinery after this Notice.
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104
Felled Log Fumigation
Termite Control, Beehive
Supers, Vault Fumiga-
tion, Japanese Beetle
Control
Cancellation effective 30 days
after this Notice.
Continued registration with label
changes imposing use restrictions;
require submission of monitoring
and use data.
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Significance .to U.S. Agriculture and Commerce and Their Pesticide
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108
Hoi tor f» R.C. and G.P. Ludvik. 1982. Ethylene Dibromide — Analysis of
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109
Ludvik, G. F. 1982 (b). PD 4 fbr EHf*. ^morandum: 11 Fteb. to U Zygadlo.
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no
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-------
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112
Whorton, D.M., and T.H. Milby. 1980. Recovery of Testicular Function Among
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Wash., D.C.
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113
Additions to References and Citations
Ground Water
Bigler, W. 1983. Personal communication to s. Cohen. Epidemiology
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Midwest Research Institute and EPA.
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114
Additions to References and Citations
Economics
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Lenahan, J.R. 1983. "Abbreviated Benefit Analysis of Ethylene
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Ethylene Dibromide Use on Tobacco,"Virginia Polytechnic
University and State University. Prepared under
cooperative agreement with U.S. Environmental Protection
Agency, CR #809256 .
Vlier, L. 1983. "Preliminary Benefit Analysis of EDB Use on
Pineapples." EAB/BUD/OPP U.S. Environmental
Protection Agency.
Zacharias, T.P., A.H. Grube and E.R. Swanson. 1983. "Abbreviated
Benefit Analysis: Ethylene Dibromide (EDB) Use for
Nematode Control of Soybeans." Department of Agriculture
Economics, University of Illinois, Prepared under
cooperative agreement with U.S. Environmental Protection
Agency, CR #809315.
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115
Additions to References and Citations
Burin, G.J
Assessment
with EDB".
, and Holder, W.J
of September 15,
TB/HED/OPP U.S.
Exposure
1983 "Comments on USDA Draft Risk
1983 for Post-Harvest Fumigation of Citrus
Environmental Protection Agency
CDFA. June 2, 1983. Memorandum to K.T. Maddy from J. Lowe, entitled
"Commodity Samples Collected in 1982 for EDB Analysis"., 1 page.
CDFA. 1983. K.T. Maddy, 1982. Complexities of the Decision-Making
Process in Determining Acceptable Hazards of Ethylene Dibromide
(EDB) as a Pesticide in California HS-1038 Cal. Dept. Food
Agric., Sacramento, Calif.
NIOSH. 1976. A Guide to Industrial Respiratory
Publication No. (NIOSH) 76-189.
Protection. HEW
OSHA. 1981. Draft of Trip Report, entitled, "Fumigation Procedures
Utilizing Ethylene Dibromide on Florida Citrus". 18 pages plus attach-
ment (unpublished).
USDA. 1983. A Preliminary Report of Research on the Effect of Ethylene
Dibromide Citrus Fumigation on Fruit Fly Control and Residue Levels
Conducted by Agricultural Research Service, USDA and Florida Department
of Agriculture and Consumer Services.
USDA. 1983. Draft Document: Quantitative Risk Assessment for
Ethylene Dibromide in it Use as a Post-Harvest Fumigant For Citrus
Fruit. Conducted by Dynamac Corporation.
418-574 0-83-9
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APPENDIX I
ETHYLENE DIBROMIDE: POSITION DOCUMENT 2/3
OFFICE OF PESTICIDE PROGRAMS
U.S. ENVIRONMENTAL PROTECTION AGENCY
DECEMBER, 1980
117
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EXECUTIVE SUMMARY
This Position Document (?D) 2/3 proposes several regulatory actions to
reduce the human health risks resulting from registered pesticidal uses of
ethylene dibromide (EDB). These proposed actions are based on the Agency's
determination that certain uses of EDB result in unreasonable adverse effects
to man. The Agency requests registrants and interested parties to review the
proposed actions and the evaluations upon which they are based, and to provide
comments or any additional relevant information. All of the registered uses of
EDB have been examined in this document. These include: preplant fumigation
of soil (to control nematodes); fumigation of stored grains (to control
insects); spot fumigation of grain milling machinery (to control insects); post-
harvest fumigation of citrus, tropical fruits, and vegetables under USDA
Animal, Plant and Health Inspection Service (APHIS) quarantine (to control
fruit flies); fumigation of felled logs (to control bark beetles); fumigation
of stored beehive supers and honeycombs (to control the greater wax moth);
vault-fumigation of stored furniture and clothing (to control various pests);
treatment of plants, soil and grass sod in accordance with the OSDA/APHIS
Japanese Beetle Quarantine Program; and fumigation beneath concrete slab
foundations of buildings and porches to control subterranean termites, and spot
fumigation of their galleries to control drywood tenriites.
The first regulatory action the Agency is proposing is to allow
registration to continue for preplant soil fumigation, the largest volume use
of EDB, However, the Agency will permit this use only.if certain restrictions
are implemented and additional data requirements are fulfilled. Specifically,
the Agency will require applicators to wear respirators and protective
clothing; reentry into a treated field will also be prohibited for 24 hours
following fumigation. The Agency is also requiring soil fumigant registrants
to conduct studies to determine if this use results in groundwater
contamination. The need for these studies is based on the concern that SDB is
structurally similar to dibromochloropropane (OBCP), a chemical also used as a
preplant soil fumigant, which has been found in many groundwater supplies. In
addition, the Agency will require registrants to provide data to demonstrate
that residues of EDB in crops grown in EDB fumigated soils at maximum allowed
application rates do not exceed the limits of sensitivity of analytical
methodology (currently 1 ppb). When results from these investigations are
available, the Agency will reexamine the adequacy of its regulatory measures
for this use.
Second, the Agency is proposing to cancel the EDB registrations for two
other major uses: fumigation of stored grains and spot fumigation of grain
milling machinery. The bases for these proposed cancellations are that the
public- health risks of cancer, heritable genetic damage, and reproductive
disorders outweigh the economic benefits of these uses. The Agency has
concluded that residues of EDB conraminate the human diet as a result of these
registered uses. Applicators, persons near a treatment site and workers who
handle treated commodities are also exposed to significant levels of EDB via
inhalation and dermal contact.
Third, the Agency is proposing that on July 1, 1983, EDB registrations for
post-harvest fumigation of citrus, tropical fruits and vegetables will be
cancelled. The interim period of allowed use will give time for the
development and' implementation of efficacious alternatives. There are
currently no effective means of protecting these commodities from fruit fly
119
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120
infestations other than BOB. However, gamma irradiation treatment methods are
currently being considered. These have been used successfully in several
foreign countries.
Fourth, the Agency is proposing to cancel the EDB registration for
fumigation of felled logs, a relatively low volume use. The basis for this
action is the Agency's determination that the potential risks to applicators
outweigh the economic benefits of this use. Based on the current application
methods for this use, the Agency has concluded that applicators may be at risk
of incurring unreasonable adverse effects resulting from dermal contact and
inhalation of EDB vapors. Because the use of the registered alternative
endosulfan would result in a national reduction in treatment costs, the Agency
has established that there are no benefits for this use of SOB.
Fifth, the Agency is proposing to defer the decision on the use of SOB for
control of termites, but in the interim will reinforce and expand current label
directions by requiring that it be used only by certified commercial
applicators; that applicators must wear protective clothing and 3 respirator;
that premises be vacated by non-applicators during fumigation and subsequent
aeration; and for use against subterranean termites, that injection holes be
plugged temporarily dur\Lng, and sealed permanently after, treatment. The
Agency defers further regulatory action on uses against termites until SOB can
be considered in a "cluster analysis" together with all other pesticides used
for control of subterranean and drywood termites (including aldrin, dieldrin,
chlordane, heptachlor, pentachlorophenol, chlorpyrifos, methyl bromide,
sulfuryl fluoride, hydroger :yanide, and silica aerogel).
Finally, for the remaining uses: fumigation of beehive supers, vault
fumigation of stored clothing and furniture, and the OSDA's Japanese Beetle
Quarantine Program, the Agency is proposing to allow these uses to continue
only if certain use restrictions are implemented and additional data require-
ments are fulfilled. Specifically, the Agency will require protective clothing
and other low-cost measures designed to reduce applicator exposures to SOB. In
addition, the Agency will require registrants of products with each of these
uses to conduct studies to determine the EDB air levels to which applicators
are exposed, the number of applicators involved in these uses, and the amounts
of EDB applied annually for these uses.
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Acknowledgements
Special Pesticide Review Division Team
Richard Johnson, Team Leader
Joseph Panetta, Project Manager
Lynn Brown, Proj ect Manager
Owen Seeder, Proj ect Manager
Cathy Kessler, Student Assistant
Wendy Weinstein, Student Assistant
Gary Otakie, Project Manager
C. Jeffrey Kempter, Section Head
Technical Support Team
James Holder, EFB, HED
Abrahan Mittelman, EF3, HED
Linda Zygadlo, SAB, BFSD
Kenneth Bailey, TB, HED
Ann Barton, HED
George Ludvik, ASI3, 3FSD
Carl Bayer, OGC
John Worthington, EFB, HED
Willard Cummings, PSB, BFSD
Henry Appleton, EFB, HED
Roger Holtorf, EAB, BFSD
Robert Heath, RES, HED
William Burnam, TB, HED
Christine Chaisson, T3, HED
EPA PESTICIDE CHEMICAL REVIEW COMMITTEE (PCRC)
Marcia Williams, Director, SPRD
Michael Winer, OGC
Allen Jennings, 0PM
John J. Neylan, OE
Donna Xuroda, ORD
Richard N. Hill, OTS
Raymond Smith, OANR
Charles Gregg, OWWM
121
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TABLE OF CONTENTS
Executive Summary
I. Introduction 1
A. General Background and Organization I
3. Legal Background 1
1. The Statute 1
2. The RPAR Process 3
C. Chemical Background 3
1. Nomenclature 3
2. Chemistry 3
3. Uses and Registration 4
D. Regulatory History 7
1. Tolerances 7
2. Pre-RPAR Actions 7
3. Post-RPAR Actions 7
II. Risk Analysis g
A. Rebuttal Evaluations and Qualitative Assessment of 9
Risk Data
1. Oncogenicity 9
2. Mutagenicity ^7
3. Reproductive Effects 24
B. Hunan Exposure to BOB from Pesticidal Uses 3Q
1. Dietary Exposures ^1
2. Inhalation and Dermal Exposures 42
123
-------
124
C. Quantitative Assessment of Risfc Data 53
1. Oncogenicity 53
2. Mutagenicity 51
3. Reproductive Effects e-|_
4. Summary and Conclusions g1
D. Risks of the Alternative Pesticides to EDB ,,
III. Benefits Summary gg
A. Introduction gg
B. Fumigation of Stored Grain gg
C. Quarantine (APHIS) gg
1. Grapefruit 7^
2. Papaya 71
3» Mango y^
4. Other Citrus 72
5. Miscellaneous Fruits and Vegetables 72
6. Summary 72
D. Spot Fumigation of Grain Milling Machinery 72
E. Preplant Soil Funigation 7-
1. Tobacco
2. Pineapple
3. Citrus
4. Peaches
5. Peanuts
6. Cotton
7. Vegetables
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125
F. Minor Uses 75
1. Fumigation of Felled Logs 75
2. Termite Control 7g
3. Fumigation of Stored Beehive Supers and 73
Honeycombs
4. Fumigation of Stored Clothing and Furniture 79
5. Fumigation of Quarantined Plants, Soil and go
Grass Sod
IV. Identification of Regulatory Options 32
A. Introduction 32
B. Legal Basis for Options 32
C. Data Gathering for Identification of Options 33
1. Additional data 33
2. Information-Gathering Hearings 33
0. Legal Options Available Under FXFRA 33
1. Classification for Restricted (7se g3
2. Amend the Terms and Conditions of Registration 33
3. Labeling 34
4. Establish or Re-evaluate Tolerances in g4
Conj unction with FOA
5. Cancel After a Specified Period of Time g4
E. Risk Reduction Measures for EDB „,-
1. Use Restrictions for All Uses of EDB gs
2. Additional Requirements for Soil -_
Fumigation Uses
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126
3. Additional Requirements for Stored Grain 37
Fumigation
4. Additional Requirements for Spot Treatment of gg
Willing and Cereal-Handling Machinery
5. Additional Requirements for Post-Harvest gg
Fumigation of Citrus and tropical Fruits.
6. Additional Requirements for Fumigation of Beehive g^
Supers
7. Additional Requirements for Vault Fumigation of g2
Stored Clothing
8. Additional Requirements for Fumigation of Sub- n?
terraean and Drywood Termites
9. Additional Restrictions for Fumigation of Bark g-j
Beetle
10. Additional Restrictions for Fumigation of g^
Japanese Beetle Under USDA Quarantine Program
V. Selection of Regulatory Options gg
A. Introduction gg
B. Fumigation of Stored Grain gg
1. Summary of Risks and Benefits gg
2. Risk/Benefit Analysis 97
C. Quarantine Fumigation
1. Summary of Risks and Benefits
2. Risk/Benefit Analysis
D. Spot Fumigation of Grain Milling Machinery ,,„
1. Summary of Risks and Benefits ...
2. Risk/Benefit Analysis ,,-
E. Pre-Plant Soil Fumigation
1. Summary of Risks and Benefits
2. Risk/Benefit Analysis ..,
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127
P. Minor Uses
116
1. Summary of Risks and Benefits
116
2. Risk/Benefit Analysis
1,18
Bibliography
Appendix 1 - Rebuttals Submitted in Response
to the RPAR Notice on EDB
Appendix 2 - List of Clearances and General
Survey of Irradiated Pood Products
Cleared for Human Consumption in
Different Countries
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TABLE NUMBER
Table
Table
Table
Table
Table
Table
Table
Table
Table
Figure
1
2
3
4
5
6
7
3
9
1
Table 10
Table 11
Table 12
Table 13
Table 14
Table 15
Table 16
Table 17
LIST OF TABLES
TITLE PAGE
Physical Properties of SDB 3
EDB Tolerances and Exemptions from Tolerances 5
Emergency Exemptions for EDB Use on Soybeans 10
Summary of Mutagenicity Testing of EDB 19
Sperm Count Distributions by Cohort and 28
Occupation
Sperm Count Distribution for Males from 29
Infertile and Fertile Marriages
Lesions in Reproductive Organs of Male Rats 30
Exposed to EDB
Calculated Dietary Burden (DB) of EDB Residues in 33
Human Diet Resulting from Soil Fumigation Uses
ZDB Residues (ppm) Reported in Fumigated Grains 34
Time Line of Wheat and Wheat By-Product 35
Distribution with Expected Times for EDB
Fumigation
U.S. Quarantine Requirements for EDB Treatment 33
Measured EDB Residues in Fruits Obtained from 40
California Wholesale Produce Markets
Estimated EDB Food Residues Resulting from 40
Required Quarantine Fumigation
Total Dietary Burden (DB) of EDB Residues in 42
the Human Diet Resulting from All Commodity
Fumigation Uses
Measured Air Concentration of SDB during Specific 45
Soil Fumigation Practies
Estimated Annual Duration of Exposure to EDB of 47
Soil Fumigation Workers
Total Estimated Annual Exposure to EDB of 43
Private Applicators/Transfer Operators during
Soil Fumigation
Inhalation Exposure off Workers to SDB at Citrus 5^
Fumigation Stations and at a Citrus Warehouse
129
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130
Table 13 Inhalation Exposure of Spot Fumigation
applicators to SDB
Table 19 Inhalation Exposure of Hill Workers
Table 20 Populations at Risk
Table 21 Summary Table of Inhalation Exposure to EDB
Table 22 Risk and Estimated Cancer Cases Per Year due to
"Probable EDB Dietary Burden"
Table 23 Risk and Expected Cancer Cases Per Year due to
"Realistic Worst Case EDB Dietary Burden"
Table 24 Upper Bound Risks and Expected Cancer Deaths
Per Year due to Ingestion of Crops Grown in soil
Fumigated with EDB
Table 25 Risk due to Occupational Inhalation of EDB
Table 26 Hunan Hazards of Substitute Chemicals
Table 27 Annual Economic impacts of Cancelling
Ethylene Dibromide
Table 28 Alternative tfematocides Used to Replace EDB
on Selected Vegetables, Cost of Materials and
Changes in Mematode Control Cost, by Crop
Table 29 Impacts of Regulatory Options on Stored Grains
Table 30 Impacts of Regulatory Options on Post-Harvest
Funigation of Citrus, Tropical Fruits, and
Vegetables
Table 31 Impacts of Regulatory Options on Spot
Funigation
54
56
57
58
62
63
64
65
66
70
77
99
105
111
Table 32 Impacts of Regulatory Options on Soil
114
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131
I. Introduction
A. General Background and Organization
The Federal Insecticide, Fungicide and Rodenticide Act, as amended
(FIFRA), requires the Environmental Protection Agency (SPA) to review the risks
and benefits of the uses of pesticides suspected of causing adverse effects to
hman health or the environment. On December 14, 1977, EPA issued a Notice of
Rebuttable Presumption Against Registration and Continued Registration (RPAR)
of pesticide products containing ethylene dibromide (SDB), a fumigant
insecticide and nematocide. The rebuttable presumption was based on validated
studies showing that EDB is oncogenic and mutagenic, and has adverse
reproductive effects on several species of animals. Since then EPA has
reviewed rebuttal comments and conducted thorough risk and benefit analyses of
the pesticidal uses of EDB.
This docvanent determines what regulatory actions EPA should take under
FIFRA to change the current use patterns of pesticides containing EDB.
Included are discussions about the risks and benefits of the pesticidal uses of
EDB, and explanations about the rationale for the Agency's proposed final
decision. This document is written in five chapters. Chapter I is this
introductory section. Chapter II summarizes and evaluates the comments
received on the RPAR, evaluates the potential health risks of EDB, and briefly
describes the laboratory evidence of toxicity, available exposure data,
available epidemiology data and the Agency's revised risk assessment. Chapter
III summarizes the use—by-use economic benefits of EDB and the assumptions and
limits of these estimates. Chapter IV describes possible regulatory options
for the reduction of risks. Chapter V evaluates the risks and benefits and
adverse impacts of each possible action for each of the nine general
categories of the registered uses of EDB, and selects the regulatory action the
Agency is proposing for each use.
B. Legal Background
1. The Statute
The FIFRA (7 U.S.C. Section 126 at sea.) regulates all pesticide
products. Under Section 12(a)(1)(A) of FIFRA all pesticide products must be
registered before they may be sold or distributed. Before a pesticide
niay be registered, the Administrator must determine that its use will not
result in "unreasonable adverse effects on the environment," which is defined
by Section 2(bb) of FIFRA to mean "any unreasonable risk to man or the
environment, taking into account the economic, social, and environmental costs
and benefits of the use off any pesticide." In sum, any decision to rsgistsr or
continue to register a pesticide must weigh both the risks and the benefits
from the use of the pesticide.
Section 6(b) of FTFRA 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/her 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."
-L-
418-574 O - 83 - 10
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132
Table 1. Physical Properties of EDB j_/
Boiling Point
Melting Point
Vapor Pressure
Specific Gravity
Solubility
Stability
Flammability
Appearance
Heat of Vaporization
Corrosiveness
Flash Point
Fire Point
Weight 4 Volume
Conversions
- -131.5JC
9.3°C
— 11.0 mm Hg § 25 C
— liquid (water @ 4°C =1)
2.172 § 20°C gas (air =1) 6.487
— 0.43 g/100 g water § 30°C, soluble
in ethanol, ether and most organic
solvents.
— Stable
— Nonflammable
— Colorless liquid
— 46.2 cal/g
vapor or liquid attacks, many
paints and some metals
(especially aluminum)
None
None
1 U.S.
1 U.S.
gallon
gallon
— 1 Ib. liquid
— 1 oz/1000 ft
3 :
1 ppm s 7.69 mg/nr
1 mg/nr = 130 ppb
18.11 Ibs.
8.215 kg.
208 ml §
1 og/liter
1 gm/ or
25°C
Density of EDB in
saturated air
Cone, of EDB in air
at saturation
-- 1.08 (air s 1)
— 1.3? by vol. e 20°C
I/ Data taken from several sources including Monro (1969),
Thomson (1977), Martin (1971), Spencer (1973), Merck (1976).
-2-
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133
The Administrator 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 Section 2(q)].
2. The RPAR Process
The purpose of Pebuttable Presumption Against Registration (RFAR) is to
gather risk and benefit information about pesticides which appear to pose risks
to health or to the environment. As described in 40 CFR 162.11, this process
is designed to allow an open/ balanced decision with participation.by all
interested groups. The RPAR regulations describe various risk criteria, and
provide that an RPAR shall arise if the Agency determines that any of the risk
criteria have been met. Cnce a notice of rebuttable presumption is published,
registrants, applicants and interested persons may submit evidence in rebuttal
or in support of the presumption. Ml parties may also submit evidence on the
economic, social and environmental benefits evidence of any use of the
pesticide. If the presumptions of risk are not rebutted, the evidence of the
benefits from use of the pesticide submitted to or gathered by the Agency must'
be evaluated and considered with the risk information. The Agency analyzes
various risk reduction methods and their costs. The Agency then determines
whether or not the risks of pesticide use may be outweighed by its benefits.
If a balance between risks and benefits cannot be reached for a specific use,
the registration for that use must be canceled or otherwise restricted, or, in
the case of a new application, denied.
C. Chenical Background
1. Nomenclature
Sthylene dibromide (SDB) is the common name for 1,2-dibromoeth,ine, CAS
number 0001060934. It is a soil and commodity ffumigant having both nematocidal
and insecticidal use. The term HDD as used in this document refers
specifically to the organic molacule, ethylene dibromide, and does not include
its breakdown products, such as inorganic bromide(s) or total bromide*s).
These latter two terns are used in the food additive tolerances (21 CFK 123)
and raw agricultural commodities tolerances (40 CFR 180).
2. Chemistry
At room temperature, pure EDB is a colorless, heavy, nonflammable liquid.
It is prepared commercially by reacting bromine with ethylene gas and has a
characteristic mildly sweet odor detectable in air at levels ranging from 10 to
25 pom (77 mg/mJto 192.5 mg/m"1). Its chemical formula is CH_3rCH.,3r,
its molecular weight is 187.38, and its structural formula is:
Br Br
I I
H - C - C - H
I I
I! H
Table T lists other chemical and physical properties of SDE.
-3-
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134
3. Uses and Registration
SDB has been produced in the United States since the 1920's and used
primarily as a lead scavenger in leaded antiknock gasoline additives. Because
of Che Agency's regulations requiring a phase-out of leaded gasoline, this use
of EDS has steadily dropped over the last few years and is expected to
eventually become negligible.
During the 1950's and 1960's, federal pesticide registrations for uses of
EDB as a fumigant were granted under FIFRA. Currently, the major registered
pesticidal uses of EDB are:
o Pre-plant soil funigation by injection for a wide variety
of food and non-food crops including vegetables, fruits,
grains, peanuts, cotton, and tobacco;
o Post-harvest commodity ftmigation for grains, fruits
and vegetables, including various State, Federal or
international quarantine programs on citrus, fruits,
nuts, and vegetables;
o Fumigation of grain milling machinery and flour mills
to control insect infestations in milling remnants and
processed milled products.
Other uses of EDB include:
o Control of wax moths in beehive supers;
o Control of mountain pine bark beetles in the western
states by Federal and State forestry agencies;
o Control of drywood and subterranean termites in
structural pest control operations;
o Control of clothes moths, dermestid beetles and similar
pests of furs, rugs, and other items in fumigation
vaults; and
o Control of Japanese beetles in the soil of balled ornamental
trees and shrubs under the APHIS Quarantine Program.
EDB is usually formulated as a liquid concentrate or as a gel. There are
122 federal pesticide registrations, held by 53 registrants, of products
containing EDB as an active ingredient, and 24 state registrations, held by 12
registrants. In addition, emergency exemptions for SDB use on soybeans
(discussed in detail in the next section) were granted to six states early this
year for use through the month of July, 1980. There are no Federally
registered products containing EDB as an inert ingredient. Most of the
registered products are mixtures of EDB and other active ingredients, such as
carbon tetrachloride/ ethylene dichloride, methyl bromide, chloroform, carbon
disulfide, sulfur dioxide, chloropicrin, and benzene.
The Agency (Holtorf, 1990) estimates that about 340-360 million pounds of
active ingredient EDB are produced annually in the U.S. by four basic
producers: Dow Chemical, Ethyl Corp., Great Lakes Chemical and PPG
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135
TABLE 2. EDB (Inorganic Bromide) Tolerances and Exemptions
from Tolerance.
Commodity
Soil Fumigation Uses
Broccoli
Carrots
Melons
Parsnips
Potatoes
Eggplants
Okra
Summer Squash
Sweet Corn
Sweet Corn Forage
Sweet Potatoes
Tomatoes
Pineapples
Cucumbers
Lettuce
Peppers
Cottonseed
Peanuts -7
Asparagus
Cauliflower
Lima Beans
Strawberries
Tolerance
75 ppm
50
Citation and Form
40 CFR 180.126
Inorganic bromides
(calculated as Br)
ppm
40 ppm
30 ppm
25 ppm
•
10 ppm
«
5 ppm
Post-Harvest (Commodity) Fumigation Uses
Barley -
Corn
Oats
Popcorn
Rice
Rye
Sorghum (milo) 2/
Wheat
50 ppm
40 CFR 180.146
Inorganic bromides
(calculated as Br)
I/ 40 CFR 180.126(a) prohibits use of treated peanut hay
~~ and hulls as feed for meat and dairy animals.
2/ 40 CFR 180.1006 exempts these grains from the require-
~~ ment of a tolerance for organic bromide residues of
EDB.
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136
Table 2 - continued
Commodity Tolerance
Quarantine Fumigation Uses
Beans (String} 10 ppm
Bitter Melons
Cantaloupes
Cavendish Bananas
Citrus Fruits
Cucumbers
Guavas
Litchi Fruit
Litchi Nuts
Longan Fruit
Mangoes
Papayas
Peppers (Bell)
Pineapples
Zucchini Squash
Cherries 25 ppm
Plums (Fresh Prunes) •
Citation and Form
40 CFR 180.146
Inorganic bromides
(calculated as Br)
40 CFR 180.146
Total inorganic and
organic bromides
Food Additive Tolerances
Milled Grain Fractions
125 ppm
21 CFR 193.225
1977 Inorganic
bromides (Calculated
as Br) from all
fumigation sources
including grain-mill
machinery.
Fermented Malt
Beverages from
corn grits and
craciced rice
25 ppm
21 CFR 193.230 (d)
(1977) Total in-
organic bromides
(calculated as Br)
from all fumigations
with bromine compounds
-6-
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Table 2 continued
Commodity
Dried Eggs
137
Tolerance
400 ppm
Parmesan and
Roquefort Cheese
325 ppm
Citation and Form
21 CFR 193.250 Total
inorganic bromides
from all organic
bromides used as a
soil, commodity, or
processed food fumi-
gant (calculated
as Br) .
Concentrated Tomato 250 ppra
Products
Dried Pigs "
Processed Foods 125 ppm
(including processed
grain and cereal products)
Milled Fractions in
Animal Feeds from
barley, corn, grain
sorghum (milo) , oats
rice, rye, and wheat
125 ppm
21 CFR 561.260(b)
Inorganic bromides
(calculated as Br)
resulting from
carry over or
concentration of
residues from
fumigation of grains
with MBr or SDB.
-7-
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138
Industries. The bulk of this production, about 230 million pounds, is used as
a gasoline additive. Pesticide usage of EDB in comparison to total production
is quite snail, comprising about four percent or 13 to 15 million pounds of
annual U.S. production. Estimates of quantities imported and exported for
pesticide usage are considered confidential and are not publicly available.
The major pesticide uses of EDB are dominated by agricultural soil fvmigant
use, comprising about 90% of U.S. consumption. The remaining 10% is used for
commodity and space ftmigation.
0. Recrulatory History
1. Tolerances
There are no tolerances for EDB per se in or on raw agricultural
commodities because it had been asguned, on the basis of data originally
submitted by petitioners, that there would be no EDB residues. This conclusion
was based on the hypothesis that the parent EDS compound had either completely
evaporated or been converted to bromide ions which were subsequently taken up
by plants as inorganic bromides. Residue analyses then available for EDB in
crops grown in treated soil were negative for the organic molecule. The
analytical method for organic bromide, employed from about 1950 through 1965,
had a sensitivity of only 0.2 to 1.0 ppm and was not specific for EDB, but
rather measured only the organic bromide ion. Consequently, tolerances were
established in 40 CFR 180 for inorganic bromides resulting from the use of EDB
in or on raw agricultural commodities, and as a food additive in processed
foods by 21 CFR 193 and 561. These tolerances are presented in Table 2.
2. Pre~RPAR Actions
On October 16, 1974, the National Cancer Institute (NCI) issued a
"Memorandum of Alert" describing a preliminary finding of EDB's carcinogenic
activity in rats and mice. On the basis of this information,the Agency began a
general review of the production and use status of EDB.
On July 14, 1975, the Environmental Defense Fund (EOF) petitioned the
Agency to investigate EDB on a priority basis and to take suspension or
cancellation action against the compound, as justified (Butler, 1975). In
November, 1975, EDB was accepted by the Off-ice of Special Pesticide Review as
an RPAR candidate, based on the final NCI study which showed SOB to be
carcinogenic in both rats and mice. After this initial petition, EOF amended
and renewed its request for action against EDB under FTFRA on January 21, 1976,
September 30, 1976, and August 26, 1977 (Hinkle, 1976, 1977).
Additional evidence for this referral included studies showing EDB to be
mutagenic and capable of producing adverse reproductive effects in several
species of animals. On September 7, 1977, the Agency's Carcinogen Assessment
Group issued a Preliminary Risk Assessment for EDB which stated, "There is
strong evidence that EDB is likely to be carcinogenic to man" (CAG, 1977).
Following intensive review and validation of the literature, the Agency
published a Notice of RPAR and the RPAR Position Document 1 in the Dec. 14,
1977 Federal Register. The basis for the RPAR is the risks to man of
oncogenicity, mutagenicity, and adverse reproductive effects as a result of
pesticidal exposures to EDB.
-8-
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139
3. Ppst-RPftR Actions
During the initial rebuttal period, December 14, 1977, to January 30, 1978,
the Agency received twelve requests for extension of the rebuttal period. The
Agency granted an extension to April 3, 1978. During and after the extended
rebuttal period, 91 rebuttal submissions were received. After the extension
deadline, several rebuttals were amended, resulting in a total of 105 docunents
in the rebuttal file (Appendix 1). Thirteen of these submissions contained
rebuttal information alone or in combination with benefits information. Thirty-
four of the submissions provided some type of benefits information only, while
an additional thirty-five contained "testimonial" statements of need which were
not supported by any data. There were several other submissions, including
support for an immediate "ban" or other action against EDB.
Following the 1979 suspension of DBCP as a preplant pesticide for soybean
nematode control, several states claimed that there are no other registered
pesticides that are economical or effective against nematodes. Based on test
results showing EDB to be as efficacious as DBCP, six states applied for
temporary permits (e.g., exemptions from FIFRA) to allow this use under section
1B(c) of FTTSA. These exemptions were granted for the period beginning April
24, 1980 and ending July 31, 1980, with nunerous restrictions to reduce health
risks to applicators. Table 3 describes these exemptions in detail.
II. Risk Analysis
The Agency issued the Notice of RPAR and Position Document 1 (PD-1) based
on three criteria: oncogenicity, mutagenicity, and reproductive effects.
After issuing the RPAR, the Agency began a detailed risk/benefit analysis
according to applicable guidelines and policies. This chapter is divided into
three sections: Section A evaluates the rebuttal comments the Agency received
following the issuance of the PD-1, and discusses the scope and quality of the
available toxicological data, including new data obtained since the publication
of ?D-1; Section B estimates hunan exposures; and Section C quantifies the
potential health risks of EDB to humans.
A. Rebuttal Evaluations and Qualitative Assessment off Risk Data
1. Oncoorenicity
In issuing the RPAR, the Agency relied on evidence of oncogenicity reported
in an NCI-sponsored study (Weisburger, 1977). This study showed a statisti-
cally significant increase in the incidence of squamous cell carcinoma of the
forestomach in both rats and mice as compared to the controls. Based on its
preliminary review of the data from NCI, the Agency stated:
.. EDB causes a significant increase in the incidence of gastric
carcinomas in both sexes of rats and mice. Metastases of these traors
are reported. The tuner rates appear to be high and the differences
are highly significant. (Anderson, 1977).
The Agency's position that an oncogenic rebuttal should arise is based on
its evaluation of this study and 40 CFR Section 162. 11(a)(3)(ii)(A). This
statute states that rebuttable presumption of oncogenicity shall arise if a
pesticide "... induces oncogenic effects in experimental mammalian species or
in man as a result of oral, inhalation or dermal exposure..." As a further
clarification of the provision, the preamble to the Agency's Interim Procedures
-9-
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Table 3. Emergency Exceptions Cor ECU Use en Soybeans (4/2V80-7/31/80)
o
location of tJbe/Appl leant
Alabawi/Depart«Bnt of
Agriculture and Industries
Pest
Soybean Cyst Heretoda
Boot-Knot Neaatode
Acreage (Haxlnnt)
160,000
olSoybean Cyst
Agriculture and Consumer Services Southern Root-Knot Nematnde
Peanut Root-Knot MemaKVte
Renifon Nenatoda
String tteroatoda
130,000
GeorgiaTbepartaenfc of
Agriculture
Tennessee /Department of
Agriculture
Soybean Cyst Mematnde
teanut Root-Knot Neroatode
Lance Neaatode
98,000
Soybean Cyst Nematoda
2,118,818
Product
Soilbroa 90GC
"Sollbroai 90BC
Soilbroa 90BC
Dow Fume W-85
Ethylene Dibronide
Hissisaippi/Departoent of
Agriculture and Conuerce
South Carolina/Oejnuon
University
Spiral
i Cyst Nenatode
Coluobia lance Nenatoda
5,000
1.000,000
Sollbrou 90EE
Sbilbrcn 90BC
Dow fiws W-85
Ethylene Dlbronide
*>-
o
SoTlbran 90EC
Restrictions on use for all above oxeai>tioi)a include>
1. Application rate »ay not exceed 32 Ibs/acre/year of EEB active ingredient
2. Ajplication is to be carried out in accordance with the suppleoantal labeling subnltted on April 1, 1980, except
uae must be United to pests authorized by this exeuption.
3. Applicators and others handling EDO oust wear protective clothing and a respirator, unless a "closed eysUaa"
is used, which prevents applicator contact with EfiB.
4. All applicable precautions and restrictions on tlte registered product label are to be observed.
5. Ma wore titan tire acreages designated above are to be treated.
6. Soybean luty frua treated fields way not be used for feed.
7. Residues of inorganic bromide must not exceed 125 ppo. in or on soybeans or 150 ppu in soybean Heal. Soybeans
with lean than 125 ppa and uoybean uual with leaa than 150 ppn inorganic bcomicle i-eslduea nay be moved in
interstate com*roe. Ilie food and Drug Administration, DICW, has been notified.
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141
and Guidelines for Health Risk and Economic Impact Assessment of Suspected
Carcinogens (May 25, 1976; 41 FR 21402) states that "... a substance will be
considered a presumptive cancer risk when it causes a statistically significant
excess incidence of benign or malignant tumors in humans or animals."
Cn the basis of the evidence summarized in Position Cocunent 1, the Agency
concluded that the cancer risk criteria had been exceeded by all registrations
and applications for registration of pesticide products containing SDB, and
that a rebuttable presumption against new or continued registration of such
products should arise.
Six respondents (Rebuttal nos. 3C, 47, 48, 64, 78 and 79) addressed
rebuttal comments to the oncogenic criterion. The Agency has divided these
rebuttals into two broad groupings, those which address uncertainties in
extrapolating to man from the laboratory studies conducted on animals, and
those studies which investigate the health of workers occupationally exposed to
EDB.
a. Response to Rebuttals of Animal. Oncogenicity
(1) Direct Response to Rebuttals
The comments addressing the uncertainty of extrapolating from animals to
man can be grouped into broad categories:
o The route of administration, intubation, was
inappropriate because human exposure would be
primarily by inhalation;
o Massive doses both obscured detection of a
no observable-effect-level (NOEL) and
overwhelmed the animals' metabolic and
detoxification processes;
o The forestomach, where tumors occurred in the
test animals, is without a counterpart in humans;
o The oncogenic response at the site of intubation
was due to an extreme
irritant effect.
The Agency has .concluded that the first rebuttal listed above is invalid.
Human exposures to EDB also result from its presence in the human diet. At
least three uses of EDB result in its presence in the human diet: fumigation of
stored grains; "spot" fumigation of grain milling machinery; and postharvest
fumigation of citrus, tropical fruits and vegetables.
In addition, the latter part of this section describes recent evidence
which demonstrates that EDB is a potent carcinogen in animals following
inhalation exposure. Midwest Research Institute (MR!), under a contract with
The National Institute of Occupational Safety and Health (NIOSH), found a.
significant increase in the incidence of tumors of the spleen, mammary gland,
adrenals and subcutaneous tissues in a group of rats exposed to 20 ppra of 1,2-
dibromoethane alone (Wong, 1979). Most recently, Hazelton Laboratories, under
a contract with NCI (1980), also found inhalation of cDB to be causal to a
statistically significant increased incidence of cancers in both rats and mice.
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The second rebuttal comment, that the massive doses overwhelmed the
animals' metabolic systems, obscuring a no-observable-effeet-level (NOEL),
is one of the most common criticisms of NCI cancer bioassay studies (Mishra,
1973a). It has been argued by the Agency (Mishra, 1978a) and SCI that the use
of maximum tolerated dose (mtd) and 1/2 maximum tolerated dose in cancer
bioassay (even in the absence of a NOEL) is now accepted by the Agency, and its
use has been included in the proposed EPA/OPP oncogenicity testing guidelines.
Results from the above-mentioned NCI study (1977) show that mice receiving only
1/2 the mtd experienced extremely high and statistically significant cancer
incidence. In addition, results from the NIOSH and NCI-sponsored studies
discussed above demonstrate that EDB is carcinogenic in animals at low doses
(20 ppm). The Agency's Interim Cancer Guidelines (41 FR 21402) state that in
the absence of definitive information to the contrary, any exposure, however
small, will incur some risk of cancer on the exposed population. In essence,
the Agency position is that there is an assumed cancer risk front chemical
carcinogens for any level above zero. The Agency concludes that this rebuttal
is invalid.
The Agency also concludes that the third rebuttal is not valid. It is true
that humans do not have a counterpart to the forestomach of rats. "However,
the site of tumorigenic effect, and the tumor cell type produced by a chemical
is known to change depending upon the animal species, dose schedule and routes
of administration used. Thus, the absence of forestomach in huaans may not
make humans immune to carcinogenic effects of EDB." {Mishra, 1978a). This
rebuttal is further invalidated by results of the NIOSH study in which inhaled
EDB was found to induce tumors of the spleen, mammary gland, adrenals, and
subcutaneous tissues.
The fourth rebuttal, that the oncogenic response was due to an extreme
irritant effect, is based on the chronic "irritation" theory of carcino-
genesis. This general theory that there is high correlation between chemicals
which are irritants and are also carcinogens has long been discarded and the
evidence against it is sunmarized in the book Carcinogenesis as a Biological
Problem (Berenbluo, 1974). Most irritants in mouse dermal tests were
noncarcinogenic and the same was true for irritants introduced in subcutaneous
and other types of exposure tests. Among the carcinogens which could be
described as irritants, there was no correlation between carcinogenic potency
of the agent and the degree of irritant inj ury produced.
(2) Pertinent New Studies
Since the issuance of PD-1, three new studies were completed which
investigated the carcinogenic potential of EDB in animals. These are the Dow
Chemical Company Rat Inhalation Study, the Midwest Research Institute Rat
Inhalation Study, and the NCI Rat and Mouse Inhalation Study.
Dow Chemical Co. Rat Inhalation Study; A final report entitled "13
Week Repeated Inhalation Study on Ethylene Dibromide (EDB) in Male and Female
Rats" (Nitschke, 1980) was reviewed by the Agency (CAG, 1980b). The study
con :isted of exposing male and female CDF (F-344) rats to 0, 3, 10 or 2076
mg/m ethylene dibromide, 6 hours/day, 5 days/week for 13 weeks for a total
of 67-68 exposures in 95-96 days. Scheduled sacrifices occurred after 1, 6,
and 13 weeks of exposures.
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Findings from the study included:
o rats exposed to 23 mg/ra EDB showed no consistent effect in any
parameter;
o at 77 mg/m EDB caused slight epithelial hyperplasia of the
nasal turbinates in animals necropsied after 1, 5 or 13 weeks of
exposure; however, 88 days after the last exposure to EDB,
no morphological difference from control animals was observed;
o rats exposed to 3076 mg/m EDB showed a definite adverse
response characterized by a decrease in body weight gain, an.
increase in liver and kidney weights, and pathologic effects in
the nasal epithelium. The nasal turbinates of rats progressed
from very slight hyperplasia of the epithelium to hyperplasia and
nonkeratinising squamous metaplasia•
The Dow report concludes:
While this study has shown that repeated subchronic exposures of rats to
77 mg/m or 3076 mg/m EDB induce pathologic changes in respiratory
epithelioa of the nasal turbinates, a subsequent post-exposure phase revealed a
lack of progress of the lesions with almost complete reversions toward normal
histologic appearance of the nasal turbinates. In view of these findings and
the lack of any lesions subsequent to repeated exposure to 3 ppm EDB, short-
term repeated exposure to these concentrations of SDB would not be expected to
result in any long term irreversible effects upon the nasal turbinates or other
tissues of the body.
The Agency (CAG, 4/30/80) has reviewed this study, noting the short
duration of exposures, and has concluded that this study involved exposures to
animals which are clearly too short in exposure duration to be of value in
determining chronic risks present from long term exposures to EDB. (CAG,
1930b).
Midwest Research Institute Rat Inhalation Study (Wong, 1979): This
study involved significantly longer exposures and lower concentrations of EDB.
This 18 month study with Sprague-Dawley rats was designed to assess the
carcinogenicity of inhaled ethylene diJbromide (EDB) and the effect of dietary
disulfiram on the carcinogenic response to ethylene dibromide. For this
purpose, the tumor response of four groups of males and females, each with a
size ranging from 120-134 animals was evaluated as follows: (1) controls; (2)
154 og/m of inhaled EDB administered for 7 hrs/day, 5 days/week for 18
months? (3) 0.05% disulfiram in the diet for 13 months, and (4) both SDB and
disulfiram.
The preliminary draft report was reviewed by the Agency (CAG, 1979). The
project officer, Dr. H. B. Plotnick, stated that although the report is in
draft form, the pathological data have been thoroughly reviewed and will not be
altered in subsequent versions. The CAG analysis states that, this report
permit us to make a direct estimate of the carcinogenic effect of inhaled ED3
and frees us from having to rely on the unsatisfactory upper bound estimates
previously derived from intubation studies.
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The authors of the MRI report found that EDB alone (group 2) and EDB with
disulfiram (group 4) produced a statistically significant increase in tumors at
several sites, compared to the group of controls. The sites are listed below.
SOB EPS S Disulfiram
Males resales Males Females
Spleen heoangiosarcoma * * * *
Adrenal tumors * * * *
Liver hemangiosarcoma XX X *
Liver hepatocellular XX * *
carcinoma
Mesentery heoangiosarcoma XX * *
Kidney renal tumor XX * *
Subcutaneous tumors XX XX
Thyroid tumors XX * *
Mammary tumors * - *
Lung tumors XX * X
* denotes statistically significant increase, p<0.05
X denotes not statistically significant
- not applicable
Thus, this study demonstrates that BOB is also carcinogenic in rats
following prolonged inhalation exposures. "A high mortality rate and a
significant increase in the incidence of tumors of the spleen, mammary gland,
and adrenals was noted in the group (of rats] exposed to 154 rag/m 1,2-
dibromoethane alone." (Plotnick, 1980).
National Cancer Institute Rat and Mouse Inhalation Study (NCI, 1980):
The possible carcinogenicity of 1,2-dibromoethane in rats and mice was tasted
by Hazelton Laboratories of America, Inc., and published recently in a cancer
bioassay under a contract sponsored by the National Cancer Institute (NCI).
In the rat study, 50 F344 rats of each sex were exposed to 77 or 307S
ag/m of 1,2-dibromoetthane by inhalation 6 hours/day, 5 days/week for a
maximum of 103 weeks. Untreated control groups comprised of 50 rats of each
sex were exposed in chambers of ambient air.
The body weights of the rats were monitored throughout the study. The mean
body weights of the high exposure group of either sex were lower than those of
the corresponding untreated controls. Survival periods in the high-dose rats
of both sexes were shorter than in the controls.
The histopathologic examination of all the major tissues and organs
revealed a statistically significant increase in the incidences of carcinomas,
adenocarcinomas, adenomatous polyps of the nasal cavity, and hemangiosarqcmas
of the circulatory system in male and female rats exposed to a 3076 mg/m"
dose level as compared to the controls.
In addition, a statistically significant increase in tumor incidences of
the following organs of rats was observed: adenomas of the pituitary in low-
dose rats of either sex when compared with the corresponding controls; and
alveolar/bronchiolar adenomas or carcinomas and fibroadenomas of the mammary
gland in high-dose female rats when compared with ths corresponding controls.
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In summary, 1,2-dibromoethane was carcinogenic for F344 rats. These
results confirm the carcinogenic effect observed in the JIIOSH study in Sprague-
Dawley rats tested by Midwest Research Institute.
In the mouse study, fifty B6C2F1 mice of each sex were exposed to 77 or
3075 mg/m of 1,2-dibromoethane by inhalation 6 hours/day, 5 days/week, for a
minimum of 78 weeks. Untreated control groups consisting of 50 nice of each
sex were exposed in a chamber to ambient air. Throughout the study, mean body
weights of high-dose mice of either sex were lower than the controls. Survival
of the low and high-dose female mice was significantly shorter than survival
for the corresponding controls.
The histo pathologic examination of all major organs revealed statistically
significant incidences of alveolar/ bronchiolar adenomas or carincinomas in
high-dose male mice as compared to the corresponding controls. In high-dose
female mice, the incidences of hemangiosarcomas of the circulatory system,
fibrosarcomas of the subcutaneous system, carcinomas or adenomas of the nasal
cavity, and adenocarcinomas of the mammary gland were significantly higher than
those in the corresponding controls.
In summary, 1, 2-dibromoethane induced a carcinogenic effect in male and
female B6C3F1 mice. The Agency (GAG) will extensively review this srudy and
evaluate data for passible use in the quantitative risk assessment for human
population exposure to 1,2-dibromoethane via inhalation.
(3) Conclusion - Animal Oncogenicity of EDB
On the basis of the discussion presented above, the Agency concludes that
the presumption of oncogenic risk as stated in PD-1 has not been rebutted,
because no respondent to that notice has sustained the affirmative burden of
proof set forth in 40 CFR 162.11(a}(4). In providing an assessment of the
"weight" or meaning of the available studies on oncogenicity of EDB to animals,
the Agency concludes that SDB is a potent animal oncogen.
b. Response to Rebuttals _gf_Human Oncogenicity
Of EPS:
In response to the human oncogenic potential of EDB, one respondent
(Rebuttal No. 3c) submitted three studies which investigated the health of
workers exposed to EDB. Each of these studies is summarized below, together
with the Agency evaluation.
(1) The Mortality Experience of 161
Employees Exposed to Ethylene Dibromide
in Two Production Units (Ott,1977)
This study was undertaken to investigate the mortality experience of
persons occupationally exposed to EDB in two manufacturing units. The emphasis
of the study was on cancer mortality and cancer due to respiratory disease.
The total cohort population consisted of 161 employees from both units.
The estimated EDB exposure and duration of exposure ranged from 1-96 ppm
and 1-16 years respectively. In both Units I and II, employees were also
exposed to several other potentially toxic chemicals, such as vinyl chloride,
carbon tetrachloride, benzene, nickel acetate and silica. The study did not
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mention the exposure levels or duration of exposure of employees to these and
nunerous other chemicals. In addition, a number of employees in Unit II were
exposed to arsenic, a known carcinogen.
The investigators reported that no increased malignancy was noted in Unit
I. The observed cancer incidence was 1 case against 3.6 expected. The deaths
from all causes were not elevated over expected deaths. In Unit II, after
excluding the workers exposed to arsenic, a slight increase in both cancer
deaths and deaths due to respiratory diseases were observed. A total of 5
cases of malignant tumors were observed in contrast to the expected incidence
of 2.2 (p—0.072). Two of these 5 cases were stomach cancers against an
expected incidence of 0.7 (p » 0.150). The remaining 3 cancer cases were also
higher relative to 0.9 cases expected (p « 0.063). The investigators concluded
that, because of the limited size of the study population and the variety of
toxic agents to which individuals in Unit II may have been exposed, it would be
difficult to interpret these findings as being demonstrative of effects of EDB
specifically, or any other specific toxic agent.
In submitting this study, the rebutters noted that it was of doubtful
significance (Great Lakes Chemical Co., 1977). The Agency has concluded the
following:
"This study shows slight increases in stomach cancer incidence and deaths
due to all causes; however, this may not be solely attributed to EDB exposure
alone, since workers were also exposed to other chemicals, and that two cancer
deaths occured in the same family (father and son)." (Mishra, 1978a)
(2) The Associated Ocrtel Company Ltd: A Mortality
Survey on Employees at an Sthylene Dibromide Plant
at Havle, England (Turner, 1977)
The study investigated the death rates of 117 persons occupationally
exposed to EDB where employment was known to exceed 4 years. Rates per 1000
man years were compared between EDB workers and the population of southwest
England. The number of man years in the four groups in the age range of 25 to
44, 45 to 64, 65 to 74, and 75 and over, were 1797, 1440, 177, 67 respectively.
The author claims that when these groups were compared with the population in
southeast England, there was no observed increased incidence of cancer deaths
in the workers exposed to EDB.
No monitoring or exposure levels of EDB in the plant are discussed.
Without knowing the exposure Levels of EDB, the Agency is unable to use this
study to assess the human oncogenic potential of EDB. (Mishra, I978a).
(3) Dibromoethane; A Survey of Employee Records at
Amlwch Factory (Turner, 1976).
This study was a retrospective investigation off the mortality experience of
workers occupationally exposed to EDB at a manufacturing plant in southwest
England. The health records of the personnel employed at the factory during
the period from 1952 to 1975 were examined. These employees were an unusual
group, in that they were preselected for employment on the basis of above
average health. Of the 297 employees known to have worked at the site, a
cohort of 273 persons was accounted for and used in the study.
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Ambient air levels of EDB in the plant were not given. Although the
duration of exposure of the entire cohort was not determined, the investigators
reported that the 31 men, who died by the end of 1975, had worked on the site
an average of 13 years.
The average age of the group was 40 years. Mortality rates for the entire
cohort were calculated and were compared to the death rate for males in an
unexposed population in the 45-64 age group in the area in which the Amlwch
Factory was located. The average ages of the test and control groups
differed. It was the researcher's opinion that this would provide the most
significant evidence of any association between EDB exposure and increased
morbidity.
The investigators determined that among the workers who died, the incidence
of deaths due to all causes as well as heart disease, cardiovascular disease
and cancer of various sites was in most cases lower than the control group (45-
64 years of age), or approximately the same as the control group. The author
attributed this lower death rate to the preselection of healthy workers prior
to employment. The authors concluded that, "it is difficult to conclude frotn
the data on this relatively small group of persons who have had regular slight
exposure to dibromoethane that there is any association between such exposure
and any particular disease."
The Agency agrees with the investigators, and also finds that it is
difficult to conclude that there is no EDB exposure-related cancer death in the
workers. (Mishra, 1978a)
(4) Conclusions-Human Oncogenicity of EDS
Based on the evaluation of the rebuttals discussed above, the Agency
concludes that, because no respondent has sustained the affirmative burden of
proof set forth in 40 CFR 162.11(a)(4), the presumption of oncogenic risk to
humans has not been rebutted. The Agency concluded that the latter two studies
conducted in England are not useful in evaluating the htanan health risk of
exposure to EDB. The Agency (CAG, 1973) considers only the first study listed
above as technically acceptable. Though it did not show a statistically
significant cancer incidence in exposed workers, the Agency concludes that the
animal data provide substantial evidence that EDB is a likely carcinogen for
huaans.
2. Mutagenieity
In PD-1 the Agency evaluated all of the available studies on the mutagenic
potency of EDB. These studies, summarized in Table 4, tested EDB for three
types of nmtagenic effects: point (gene) mutations, chromosomal aberrations and
primary DNA damage. Each of these categories was further subdivided into
positive or negative mutagenic effects. These are the conclusions reported in
the PD-1:
"In a memorandum dated 9-10-77, Dr. R. Pertel stated that there is ample
evidence to fulfill both the multitest criteria for EDB as a mutagen as
well as the scientific criteria of EPA's Science Advisory Board's (SAB)
study group on mutagenicity. This evidence shows EDB to be positive in
both prokaryotic (microbial) and eukaryotic (higher forms including
mammals) for point ,(gene) mutational effects, with and without mammalian
metabolic activation." (December 14, 1977; 42 FR 240, page 63141)."
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40 CFR 162.11(a)(3)(ii)(A) states that a "... rebuttable presumption shall
arise if a pesticide's ingredient(s),.. induces autagenic affects as determined
by multitest evidence." Further, Section 162.3(4) defines the term tnutagenic
as "... the property of a substance or mixture of substances to induce changes
in the genetic complement of either somatic or germinal tissue in subsequent
generations." Based on the induction of point mutations by EDB in several
tests, the Agency concluded that the mutagenic risk "... index has been
exceeded by all registrations and applications for registration of pesticide
products containing EDB, and that a rebuttable presumption against new or
continued registration of such products has therefore arisen." (December 14,
1977, 40 PR 240, page 63135).
a. Mutagenicity Rebuttals
Four respondents submitted rebuttals specific to this presumption of the
autagenic risk of EDB (rebuttal nos. 3c,47,48,64). Rebuttal comments included
general arguments about 'the mutagenicity testing systems used and specific
statements about the studies reviewed in ?D-1. These rebuttals, together with
the Agency's scientific review and evaluation, are summarized and responded to
in this section. Mutagenic studies on EDB which have become available since
the EDB PO-1 was issued are also evaluated.
(1) General Comments
The rebuttals which relate to the mtitager ;,city RPAR express four general
areas of concern: the significance of the testing systems; the limitations of
the tests on EDB? available-information; and the validity of specific studies.
(a) Significance of Mutagenicity Tests
The Great Lakes Chemical Corporation. (Rebuttal No. 3C) and the Hopes
Company (Rebuttal No. 64) questioned whether in vitro (or "test tube") tests
indicate a potential for in vivo nutagenicity or carcinogencity:
"While EDB has produced some mutations in in vitro testing, the
significance of these results in assessing the mutagenic or
carcinogenic risks of EDB is not established and subj ect to serious
scientific debate." (Rebuttal No. 3C).
Ethyl Corporation (Rebuttal So. 43) also questioned the predictive utility
of existing test systems. They mentioned microbial, insect, and cell culture
studies which require extrapolation of results to apply to humans: "...The
ability of SDB to induce mutations in a variety of test systems Ls only
suggestive of its potential to induce mutations in the human population..." and
"...there is no evidence to determine the relative risk..." (Rebuttal No. 43).
In response, the Agency supports the mutagenicity studies of non-human test
systems. Data from non-mammalian test systems are relevant in considering the
potential mutagenicity of a compound. In the absence of adequate mammalian
systems which are sensitive enough to exhibit the many mechanisms of possible
genetic damage in reproductive cells, other test systems are utilized to expose
the chemical's intrinsic capacities to alter genetic components. This evidence
has generated a presumption of hazard as stated in the PD-1.
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Table 4 Summary at Mutagenlclty Testing of EDB
Genetic Event
and
Test System
Gene (Point) Mutation
Bacteria), In vitro
Bacterial, llost-
Mudiated Assay
(mouse)
Eukaryotic Mlcroblal,
ifi v*tro
Insect, In vitro
Somatic Cell
Culture In vitro
Higher Plants
Higher Plants
Bacterial, in vitro
Bacterial, in vitro
Bacterial, llost-
HudiaLed Assay
(mouse)
Species/Strain/Type
Salmonella typhlmurhro
• his G ^6
TA T530, 1535, 100
S.typhlmurlira
G 46/hls
Netirospora crassa
' ai'-3" '
Drosophlla melanogaster
males
Mouse Lymphoma cells
L517By TK lloterozygotes
TradescantiaL
Mutable Clones
Barley Seeds
S. typhimurlum
his G 46
TA 1538
8. typhlnmrlun)
LT 2
3al-clil A
S. marcescens
A 21/lcu
Concentration
or
Dose
10-10,000 ug
(10 ul)/ plate
500 «*jAg
i.m. to mouse
1.2-1.63 ul/nl
0.3 niM fed
ad. lib. 3 days
1.0-3.0 Brt
for 2, liours
3.6 - 222.9
ppra (gaa)
0.1-1.1 mH
11.5 UH
19 ul/plate
5 ul/plate
500 nq/kg
i.m. to moitsa
Genetic Indicator
or
Effect
Reversions by
Base-Pair
Substltlon
Reversions
Recessive Lethala
Sex-linked
Recessive Lethala
Induction of
TK lloraozygotea
Stamen llalr Color
(blue to pink)
Oilorophyl 1
Mutations
Reversions by
Frame-Shift
Deletions
Reversions
Result References
Positive (Bran, et. al, 1974)
., (Buselwaler, et al, 1972)
m/o H^(McCann, et al. 1975)
Positive (Buselmaier, et.al, 1972)
Positive (De Serres, at al, 1970)
K/o HA (Mailing, 1969)
Positive (Vogel, et al, 1974)
(early gem
cells affected)
Positive (Clivo, 1973)
(dose response)
Positive (Nauman, et al
(dose response) 1974} (Sparrow
et al.)
Positive at (Ehrengerg,
lir0 et al., 1974}
Negative (Breo, et al, 1974)
w/o Mh
Negative (Alper, et al, 1975
w/o MA
Negative (Buselmaier, et al.
1972)
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150
Experimental animals are utilized throughout the various disciplines of
toxicology to predict adverse effects and the probability of inducing certain
effects in humans for a given range of doses of a compound. Certainly there
exist numerous examples of cases where humans did not display the anticipated
effect predicted from animal studies. Hunans have also shown effects not
demonstrated in the experimental studies, or have been more or less susceptible
than the non-human species. However, the theorum that "the basic biological
mechanism explored and documented in experimental studies with non-human
subjects is valid when extrapolated to humans to predict risk," still holds
firmly, as evidenced by the universal acceptance of non-human experimentation
in science. (Chaisson, 1978)
Predicting potential of a compound to induce mutagenic effects in humans is
more difficult than predicting other types of toxicities, but the logic can
still be founded on establishing the mechanism in appropriate non-human
species. This concept is discussed at length in the DHEW document by the
Subcommittee on Environmental Mutagenesis, 1977. Valid studies demonstrating
mutagenic effects in experimental animals, and the mechanisms of those effects,
coupled with serious consideration of pharmacologic principles and biodistri-
bution in humans do establish the framework for presuming a rautagenic hazard to
humans. The evidence of mutagenic potential in non-human species can be used
to predict potential for humans.
The application of test results was addressed by the Great Lakes Chemical
Company: "...None of the test systems used were capable of detecting anything
other than short-term effects of a mutagen. The same applies to the
evaluation'of the genetic risk." (Rebuttal No. 2C).
The philosophy summarized above has been considered by EPA and is addressed
in the document by the DHEW Committee to Coordinate Toxicology and Related
Programs, 1977. The problems in definitively identifying human rnutagens are
recognized." However, interpretation of the available test results with the
pharmacokinetic and biochemical considerations, and matching of results of
reproductive studies can give presumptive evidence on which hazard to hunans
can be predicted and regulatory decisions contemplated (Chaisson, 1978).
Great Lakes Chemical Co. expressed a related point: "Even an established
human mutagen is not likely co have any mutagenic effect unless the exposure
reaches the testes or ovaries." (Rebuttal No. 3C).
The Agency agrees completely with this statement. It is obvious that in
order to have a heritable effect, the mutagen must reach the reproductive
tissue. As discussed in the next section, the available reproductive studies
provide evidence that the reproductive tissues in exposed animals can be
adversely affected by EDB.
(b) Limitations of Available Tests
Hopes Company states that there is a necessity for a multitest approach to
mutagenicity testing, with strong emphasis on those tests which relate directly
to man, and that the only real way to test for heritable mutation in man is to
utilize a test system with guidelines from the DKEW document "Approaches to
Determining the Mutagenic Properties of Chemicals: Risk to Future
Generations." The Agency agrees with the principle set forth in this docizient
that a multiple-system approach is necessary since no single adequate test
exists. Hopes Company has outlined the optimal criteria, but has failed to
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cite what the species and test protocol would be. The Agency recognizes the
shortcomings of each test system but also the utility of the tests when they
are considered as a group.
(c) Validity of Specific Studies
The Douglas Chemical Company criticized the 3uselmaier, 1972 study:
"Response data indicated the data presented are insufficient for evaluating the
effect of EDB in the host-mediated assay with S^ marcescens, since results of
only a single dose were reported." (Rebuttal No. 47).
The Agency agrees that an ideal protocol in the host-mediated test would
include at least three dosage levels, with at least ten animals per dose
level. Utilization of a different protocol tempers the resulting strength of
conclusions, but does not nullify the fact that the 500 mg/kg dose
(subcutaneous) increased the mutation frequency over the control group by a
factor greater than eight.
The rebuttor also rejected the use of the inconclusive results of Epstein
et al., 1972, to support the RPAR. The rebutter's reasons for this position
were unclear. The Agency did not use this study to support the presumption of
hazard; the study was mentioned to establish that it was considered, but that
the results were inconclusive.
In addition, the rebuttor disagreed with EPA's rejection of the results
ofBrem, (1974) and implied that the single dose used in the study was evidence
of no nmtagenic potential. The rebutter's position is not adequately
developed. EPA has considered this study to be invalid because no information
on the effective dose or range is given. Also, the strain used, S.typhimurium
TA 1538, would not be expected to predict activity since this strain is
designed to detect frameshift mutagens and EDB is more likely to cause base-
pair substitution mutations. The rebutter's position does not rebut the RPAR
presumption.
b. Agency Position o_n Mutagenicity Rebuttals
The Agency has reached the following general conclusion on all the
rebuttals submitted in argument against the Agency's position in PD-1:
"The methodology currently used in mutagenesis assay studies has been
generally accepted on theoretical grounds and offers the only means to predict
adverse genetic effects in hunans." [and] "The comments in the Rebuttal Nos.
2C, 47, 48 and 64 underscore the limitations of these test systems but do not
rebut the Agency's presumption of hazard as outlined in the RPAR document."
(Chaisson. 1973).
Thus, the Agency concludes that the mutagenic risk as stated in the RPAR
Notice has not been rebutted, since no respondent to that Notice has sustained
the affirmative burden of proof set forth in 40 CFR 162.11 (a)(4).
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c. Re-evaluation £f Mutaaenicity Data and Review
of New Studies
In the light of recent research, the Agency has re-evaluated the
rautagenicity data presented in the RPAR Notice and reviewed additional studies
as to the mutagenic potential of EDB.
In the PD-1 the Agency concluded that "no positive chromosomal damage
studies have been found for EDB." After a review of the study by Ehrenberg, e_t
ai ., (1979), the Agency (Mauer, 1979) has concluded that, in addition to the
point (gene) mutations cited in the PD-1, this study also demonstrates that EDB
causes chromosome-damaging effects as discussed below.
EDB was shown to cause chromosome exchange in barley seeds which were
treated with 1.4 mM of EDB for 24 hrs. Cells were analyzed for chromosomal
aberrations in the first mitosis following treatment. The observed frequencies
of induced chromosomal aberrations were determined to be significantly higher
than the control material.
Additional studies, not available at the time of the RPAR IJotice, have
since been reviewed by the Agency (Mauer, 1979). These studies lend additional
support to the Agency's position that there is multicast evidence indicating
that SDB Induces mutagenic effects in laboratory tesr systems. The studies
cited below all show positive effects. They are discussed according to the
specific genetic indicator involved, i.e.: (1) point (gene) mutation; (2)
chromosomal aberration; (3) primary DNA damage.
(1) Point (gene) mutation
SDB at concentrations as low as 0.2 parts per million has been shown to
induce sex-linked recessive lethal mutations in Drosophila melanogaster (Kale
and Baum, 1973). Early germinal stages were affected at a rate 3 times as
great as the spontaneous mutation rate, indicating that even lower
concentrations could cause mutagenic effects.
EDB has also been shown to cause reverse mutations in Aspergillus nidulans
and Sscherichia coli as well as induction of ochre suppressors in E.coli
(Scott, B.R., £t ^1 , 1978). The potency of EDB was shown to increase with
metabolic activation by a plant extract of Tradescantia clone 4430.
(2) Chromosomal damage
EDB produced micronuclei in tetrads of microsporogenesis of Tradescantia
clone 4430 by a 6-hour treatment with 20-160 ppa of SDB gas (Ma, et al.,
1978). A range of 0.001-0.002 micronuclei/tetrad/ppm-hr. was established by
do se-e ffect exper iments.
(3) Primary DNA damage
SDB was shown to indirectly interact with nucleophilic sites and strongly
inhibit RNA transfectivity via the production of "half-suistards" (Xondorosi,
et al., 1973). Q -RNA was inactivated by EDB in the presence of thioglycol
after treatment for 1 hr. in a phosphate buffer.
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153
These recent studies, not available at the time PD-1 was issued, reaffirm
the results of earlier citations and indicate that in addition to causing point
(gene) mutations and primary DNA damage, EDB possesses chromosome-damaging
affects as evidenced by several in vitro assays.
An additional study investigating the potential mutagenicity of EDB in the
rat and mouse has been reviewed by the Agency. The study, an investigation of
dominant lethal mutations, concluded that EDB at a dosage of 10 or 30 mg/kg in
mice and 100 or 150 mg/kg in rats did not induce dominant lethal mutations in
either of the species (Teramoto, et al., 1980).
It is the Agency's position (Mauer, 1979) that the- negative results of this
test are no indication of other genetic events which can occur as a result of
the transport of EDB or its metabolites to mammalian germ calls. The genetic
end-point of this test is gross chromosomal damage, a relatively insensitive
and limited indicator of total genetic damage. This test does not detect the
variety of genetic damage demonstrated in the other test systems reviewed by
the Agency. Thus, the Agency concludes that this study is of very limited
significance as compared to positive mutagenicity assays en SDB in multiple
test systems.
d. Conclusions
3as«d on the evaluation of the rebuttals and new studies discussed above,
the Agency concludes that no respondent has sustained the affirmative burden of
proof set forth in 40 CFR 162. 11 (a) (4), and that the presumption of oiutagenic
risk to humans from EDB has not been rebutted. The Agency (Mauer, 1979) states:
"Sufficient evidence exists to indicate SDB presents a potential tnutagenic
risk for humans, especially for individuals exposed to the relatively high
levels of the chemical measured in occupational settings, such 33 during
soil application and commodity fumigation. In summary, the evidence is as
follows:
o EDB is a potent mutagen, producing a broad spectrum
of mutational events in submammalian in vicro systems,
higher plant, and_mammalian cell cultures.
o EDB is mutagenic to germ cells in vivo, as shown by
the sex-Linked recessive lethal test in Drosophila,
including significant increases in lethals in a dose-
dependent fashion.
o Notwithstanding the removal of a major portion of EDB
administered experimentally to mammals, EDB is
transported to mammalian germ tissues in amounts
sufficient to produce significant effects as indicated
by sperraatogenic effects in bulls and rats. In
addition, tissue distribution studies show measureable
[sic] amounts can be transported to testicular tissue
which may result in an accumulation of genetic lesions
induced by this bifunctional alkylating agent. "(Mauer,
1979).
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154
In regard to the suitability of the data to support a quantitative estimate
of mutagenic risk, the Agency asserts:
"Although there is a strong indication of risk at current levels of
occupational exposures, the present data base does not permit
quantification of mutagenic risks from the levels of EDB exposure
likely to be encountered by the general population. As discussed
by an EPA consultant...no coherent body of relevant data is
available which could either be used to relate hunan EDB exposure
directly to mutagenic events in any mammalian test system, or from
which dose-response relationships can be extrapolated to hunans.
Further, previous indirect attempts to quantify risk from mutagenic
studies in Djrosopfrila did not take into account differences in mutational
responses between ionizing radiation and many chemical rautagens...
Also, there are basic differences in transport mechanisms between
mammals and Drosphila which can affect the pharmacokinetic disposition
of chemicals, especially via the inhalation route of exposure.
Experimental work is currently in progress for estimating the mutagenic
risk of EDB... patterned after studies already published on EMS...
This approach will attempt to overcome the previous shortcomings of
quantitative risk estimation mentioned above by utilizing a common
unit of 'dose1 to the germ lines of both Drosophila and male mica
exposed to radioactive-labeled EDB. This 'dose1 is defined as the
amount of chemical bound to germinal DNA and is measured as the nunber
of alkylationa per DNA-nucleotide. The 'dose'-mutation curve in
Droaophila will be compared to.the exposure-'dose1 curve in the mouse.
In this way it may be possible to derive a quantitative estimate of the
genetic hazard to hunans from a given concentration or exposure level
of EDB, since one could estimate the dose (as alkylations) to mammalian
germ cells from given body exposures, and the genetic consequence of
that dose in the Drosophila "test." (Mauer, 1979).
3. Reproductive Effects
In Position Docunent 1 (PD-1), the Agency cited several studies in bulls
and rodents which established that 2DB could adversely affect mammalian
reproductive development by interfering with the production of male gametes and
the development of embryos. Adverse effects in hen egg production were also
noted. In summary, the animal studies reported the following effects:
Bulls - reduced sperm production; reduced sperm motility; and
abnormal sperm structure. (Amir, 1973; Amir and Lavon, 1976; Amir and
Ben-David, 1973)
Rats and mice - selectively damaged spermatogenic cells resulting in
"transient" sterility; decreased fetal implants and fetal weight.
(Edwards et al., 1970; Short et al., 1976)
Chicken Egg Production - reduced egg weight; reduced egg
production; reduced fertility; generalized reduction in the
permeability of ovarian membranes. (See Table 9, of ?0-1)
An Agency Working Group concluded that the reproductive effects studies met
the RPAR risk criterion stated in 40 CFK 162.11 (a)(3)(ii)(B), that a
rebuttable presumption shall iriae if a pesticide "produces any other chronic
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155
or delayed toxic effect in test animals at any dosage...which is substantially
higher than that which hmans can reasonably be anticipated to be exposed."
The Working Group also concluded that, because sufficient data did not exist
for determining a no observable effect level for EDB via oral, inhalation or
dermal routes of exposures, acceptable levels of exposure could not be
calculated for persons exposed by any of these routes following the pesticidal
uses of EDB.
Based on the above evidence, the Agency adopted the following position in
the PD-1:
"On the basis of scientific studies and information
summarized in the Position Docunent [(1)], the Agency has
concluded that the risk index for reproductive effects has
been exceeded by all registrations and applications for
registration of pesticide products containing EDB and that
a rebuttable presumption against new or continued
registration of such products has therefore arisen."
Four rebuttals (Rebuttal nos. 2C, 48, 64, and 79) were submitted in
response to the reproductive RPAR. The Agency has divided these into two broad
groups: those which addressed uncertainties in extrapolating to man from the
positive animal laboratory studies; and those studies which investigated the
health of workers occupationally exposed to SDB.
a. Response to Rebuttals of Extrapolating
from Animal Reproductive Disorder to Humans
So rebuttals seriously questioned the validity of the animal reproductive
studies evaluated in the PD-1. However, all respondents noted the
reversibility of the effects at all but the highest doses in hens and the
general reversibility of effects in bulls following cessation of dosing.
Respondents argued the effects produced in hens are probably specific to the
hens and that the bull is specifically sensitive to EDB.
Generally, the rebuttals disputed the significance which the Agency placed
on the animal studies in the PD-1. More specifically, the rebuttals argued
that the reproductive disorders observed in bulls orally administered EOS
cannot be used to determine a safe level of hunan exposure to inhaled EDB. The
basis for this argument was that the bull is unusually sensitive to EDB. In
addition, the rebuttals contended that it is inappropriate to determine a
margin of safety by comparing levels to which hunans are exposed via inhalation
with the amount of EDB to which bulls were exposed orally.
The Agency concludes these rebuttals are not valid and do not change the
Agency's position. In the absence of adequate hunan data, the Agency's normal
policy is to use data from the most sensitive species which in this case is the
bull. This procedure is dictated by regulatory prudence; in the absence of
adequate h\snan data it is reasonable to assune that man is at least as
sensitive as the most sensitive species for which data are available. The
question of assorting that all EDB inhaled is retained is basically similar to
the question of the most sensitive species: in the absence of adequate data it
is prudent to assuae that the worst case applies (e.g., all inhaled EDB is
retained). Thus, the Agency concludes that it is in the interest of public
health to use the results from the reproductive studies on bulls to evaluate
the reproductive risks to hunans. In further support of this assumption, the
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156
Agency has recently completed an inhalation study on rats (discussed later in
this section) which demonstrates that this exposure route also causes
deleterious effects upon the reproductive organs.
b. Response _to Rebuttals Addressing Human
Studies
In response to the reproductive RPAR in the PD-1, two epidemiology studies
were submitted (Rebuttal no. 48). At the same time the Agency conducted its
own study (Griffith, et al, 1978).
The first study submitted in rebuttal was a retrospective study of inferred
fertility of married men occupationally exposed to EDB (Wong, 1977). Basic
marital reproductive histories were collected from five groups of male workers -
one group from each of four SDB manufacturing plants in the U-S. and a fifth
group from a plant in Great Britain. For each of these groups, expected and
observed births were compared for the families of workers exposed to EDB.
Basically it was the conclusion from each of these "mini" studies that expected
and observed human fertility were essentially the same and thus there was no
evidence that EDB had an effect upon human fertility.
The Agency concludes that this study is of limited value in evaluating the
human reproductive hazards of EDB. The Agency bases its rejection on numerous
inherent weaknesses in the study and the general fact that negative fertility
studies such as these are a very insensitive measure of the possible
reproductive hazards of EDB. Two of the deficiencies in these studies, which
were also noted by the author, included: 1) none of the U.S. groups had
matching controls; and, 2) the data for the U.S. groups were compared to
fertility data published by the National Center for Health Statistics which
included non-married women, while the plant data did not, thus tending to
artificially inflate the plant rates.
The second rebuttal study (Ter Haar, 1973) presented summary results of a
sperm count survey of 59 employees of an EDB manufacturing plant at Magnolia,
Arkansas. (This study was also referred to in rebuttal number 3C.). Workers
were divided into two groups: those exposed to air levels of less than 0.5 ppm
EDB and those exposed to levels between 0.5 - 5.0 pom.
The Agency concludes that this study is of limited value in evaluating the
possible reproductive hazards of EDB. In general, the Agency considers sperm
count studies such as this one, which are negative, to be insensitive
measuresof the possible human reproductive hazards of a substance.
Reproduction is comprised of numerous facets, only one of which is the sperm
count in males. Other parameters in males, including the number of abnormal
sperm cells, motility of cells, and ultimately male fertility, can be
affected. In addition, the potential effects on female reproduction must also
be examined, even if a substance has been demonstrated to have no apparent
effects on male reproduction. However, human sperm count studies which are
postive and were conducted according to scientifically accepted protocols, do
provide adequate evidence to demonstrate that a substance possesses risks of
disorders to human reproduction. In addition to these general considerations,
this particular study has specific technical flaws, including: 1) the failure
to document or substantiate the finding of correlation between sperm count and
exposure index; and 2) the failure to provide documentation on how workers were
chosen for the study, the percentage of all exposed individuals included in the
study, and the individual exposure estimates.
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157
c. Recent Agency Sponsored Study
The Agency study (Griffith, et al., 1973) was undertaken to provide
additional information on potential health effects of agricultural uses of EDB,
with particular focus on reproductive effects. Semen samples were obtained
from a total of forty-four individuals in four cohorts: (1) citrus fumigators
at two locations in Florida; (2) rice funigators in Texas; (3) citrus
fumigators in Texas; and (4) a mixed group of carrot farmers and researchers in
New Jersey. Semen samples were immediately analysed for volume, sperm density,
and motility. In addition, blood samples were drawn from all participants and
tested for blood chemistries, testosterone levels, certain hormones and
organochlorine residues (only for the Florida and Texas cohorts).
Air monitoring for SDB was conducted on a very limited basis. The .limber
of data points were inadequate for use in standard statistical analyses to
determine if SDB had a discernable effect on observed sperm measures.
Initially, lifetime days of use and use-index (average pounds per day of use)
were multiplied together and used as a surrogate measure of potential exposure
to determine if an inverse relationship existed with the measured sperm
counts. This surrogate was used because _the Agency had very little data on the
exposure to SDB of users. The Agency has since concluded however, that this
surrogate exposure is an invalid measure of potential exposures to EDS. Decent
monitoring studies demonstrate that citrus funigators have significantly higher
EDB exposures (on a yearly basis) than any other group of EDB users, and yet,
this is one of the smallest volune uses of EDB. In contrast, soil fumigators
use considerably more SDB, but are exposed to considerably lower levels of EDB
than the citrus f unigators, because they soil-injected EDB outdoors using
tractor-drawn chisels. Thus, this surrogate use index (days x Ibs. applied per
day) was a very inaccurate measure of the actual exposure to EDB for each
cohort.
The Agency has sunmarized the sperm counts of the cohorts from this study
in Table 5. In addition, in Table 6, the Agency has summarized results
fromstudies conducted by McCloud which investigated sperm counts for males
from"fertile marriages" and from "infertile marriages".
The Agency is reexamining the results from its study, but recognizes that
the study will have very limited value to assessing the reproductive hazards of
exposures to EDB. The study consisted of a very small number of individuals (a
total of forty-four) and a much smaller numbers of individuals within each of
the 4 cohorts. Standard statistical test results which take into account
age and sex consist of such small sample sizes, would be of limited
reliability.
d. Recent Agency Animal Study
The Agency has sponsored a study in which certain reproductive parameters
were measured in rats exposed to EDB via inhalation (Short et al., 1978).
While a variety of reproductive effects were noted in this study, the most
noticable effect was atrophy of the prostate as illustrated in Table 7 below.
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TABLE 5
SPERM COUNT DISTRIBUTIONS Mf COHORT AKD OCCUPATION
Hadian fi
Cohort Count Frequency Distribution ($) at Counta (10 at) by Cohorts jfcounta
Stata Occupation ( x 106/ml) <\0 10.1-20 20.1-40 40.1-60 60.1-100 >100 _<20 (106/n>1)
00
1 Florida Cltrua Punlgatora 53-5 14-3 7.1 14.3 21.4 7-1 35-7 21.4
(N=14)
Texas Cltrua Fumlgatora 59-5 5.9 0 23.5 23.5 17.6 29-4 5-9 £
(N=17) 0°
Texaa Rice Fumlgntora 76.4 000 12.5 50.0 37.5
New Jersey Carrot Farmera & 123.0 0 0 0 0 20.0 60.0 0
Reaearchera
-------
TABUJ 6
SPENM oouwr DiswiuuncNS toa MAI.ES FRCH INFERI-IIS AND FEKTIU HAMUAT,ES
Median 6
Count tVaijuency Distribution (1) of Counts (10 nil) by Cohorts iCounta
(10%H <10 10.1-20 20.1-40 40.1-60 60.1-100 >100 _<20 (I
10 Macl*od (H=9,000> 74 U.9 6.1 11.4 11.8 25.3 36.5 15.0
1977*
(N-1,000) 90 12 12 27 44
'Males from infertile inarriayea
"Hales frun fertile niarrlcKjes
+ Cateyorica <10 and 10.1-20 confined
-------
160
Table 7
Lesions in Reproductive Organs of Male Rats Sxposed to £DB
For 10 Weeks and Sacrificad at the End of Exposure
Lesion
Test is
Atrophy (Severe)
Calcification
Epididyrais
Atrophy (Moderate to
Severe)
Prostate
Atrophy (Moderate to
Severe )
Prostatitis
Seminal Vesicles
Atrophy (Moderate to
Severe)
EDB
£
a/
0/10^'
0/10
0/10
0/10
0/10
0/10
(ppm)*/
19
0/10
1/10
0/9
0/10
0/10
0/10
39
0/10
0/10
0/10
10/10
0/10
0/10
as
6/6
2/6
5/6
6/6
1/6
6/6
* ppm in inspired air.
Number of rats affected/number of rats inspected.
The results of this study suggest that the prostate is the most sensitive
tissue. Thus, while the testis, epididymis, prostate and seminal vesicles are
markedly atrophied in the presence of 88 ppm EDB, only the prostate is affected
at 39 ppm. Based on this study, the NOEL for atrophy of the prostate is 19 cpra
(146.11 mg/m ) in the rat.
e. Conclusions on the Reproductive Effects STAR
The Agency has examined the rebuttals submitted and other pertinent data
and has concluded that the presumption of reproductive disorders as stated in
the RPAR notice has not been rebutted because no respondent to that notice has
sustained the affirmative burden of proof set forth in 40 CFH 162. 11 (a)(4).
While there are no reliable human data available to help assess the human
reproductive effects of EDB, the available animal data clearly indicate that
SDB causes adverse reproductive effects in the bull, rat and hen. The
inhalation NOEL for EDB in the rat is 19 ppm (146.11 ng/mg"'). based on atrophy
of the prostate. Based on this NOEL and the exposure levels discussed in the
next section, the Agency concludes that (as was originally stated in PD-1 with
respect to the bull) there is not an ample margin of safety from adverse
reproductive effects for humans exposed as a result of the current pesticidal
use practices of EDB.
S. Human Exposure To EDS From Pesticidal Uses
Human exposures to EDB from pesticidal uses occur through three exposure
routes: dietary, inhalation by evaporation of pesticides containing ECS, and
dermal by contact with these pesticides.
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161
1. Dietary Exposures
Residues of EDB may enter the human diet as a result of she
following raaistsred uses:
o preplant soil funigation of agricultural commodities and the
possibility of groundwater, and, ultimately, drinking water
contamination resulting from this use;
o post-harvest fumigation of stored grains and grain products;
o fumigation of grain mills, mill machinery, and handling equipment
(including transportation equipment)?
o post-harvest fumigation of fruits, nuts or vegetables for quarantine
purposes;
o possibly through control of wax moths in beehives and associated
equipment.
In the next five sections, dietary axposure levels resulting front each of
these registered uses are examined. These data are taken from two major
investigations on SDB residues occurring in the hunan diet: "Dietary Burden of
Ethylene Dibromide Used as Soil, Grain, Grain Machinery, and Fruit Funigant"
(Holder, 1979), and ""Final Dietary Exposure Analysis for Sthylene Dibromide
Resulting from Residues in Fumigated Crops and Food Commodities" (Worthington,
1978).
a. Residues From Preplant Soil Fumigation
The Agency has examined the four known studies which investigated EDB
residues in crops grown in EDB-fumigated soil. These include the following:
o An unpublished series of reports to the Great Lakes Chemical Corp.
from Litton Bionetics, Inc. (Rebuttal No. 3C);
o An unpublished report from the Ministry of Agriculture and Forestry
of Japan (Kenichi, 7978);
o Data compiled by the Food and Drug Administration, DHEW, from their
Compliance Program for OBCP and EDB;
o A report by the California Department of Food and Agriculture (CDFA)
analyzed 29 samples of nine crops grown in EDB-funigated soils
in California, with a stated level of detection of 1 part per billion
(Maddy, 1979a).
Taken collectively, these studies indicate that residues of EDS in crops grown
in EDB-fumigated soils are, if they occur, below the level of instrunent
detection. However, the Agency cannot be certain that residues will not
occur. Each of these studies has been carefully reviewed by Agency scientists
and each was found to have some deficiencies which precluded the Agency from
categorically accepting their findings. The studies from both Litton Sionetics
and Japan's Ministry of Agriculture and Forestry used analytical procedures
which wera only sensitive to 0.01 ppm and involved application rates of EDB
which were generally less than standard rates. The FDA study involved analysis
-31-
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162
of foods obtained from retail groceries with no knowledge that EDB was even
applied to the soil in which these crops were grown. In addition the
analytical method was only sensitive to 0.01 pan. The CDFA study (Maddy,
1979a) is probably the most convincing of all the studies to date. The level
of detection is stated to be 0.001 ppm. However, because the analytical method
used was not validated by CDFA through mass spectrophotometry, these data must
be considered as preliminary.
The fact, that residues of the chemically related pesticide DBCP (in the
.001-.01 ppm range) have been found in crops treated by similar use patterns,
augments the concern that residues of EDB may occur. Therefore, in view of
these findings, the Agency assumes that treated crops can bear EDB residues up
to the limit of detection, which the Agency considers to be 0.001 ppm.
Using the 0.001 ppm residue limit, the Agency has calculated the potential
body burden which may result from soil fumigation uses (Table 3). The body
burden is calculated in mg EDB/kg body weight/day, assuming a 1,500 g diet and
a body weight of 60 kg. The 60 kg body weight value is considered to be the
average for an individual from a family of four. The food factors (the average
percentage of the human diet) listed are the values reported in the update of
the Food Factor Tables (Schmitt, 1973). The percentages of crops currently
treated are docuner.rad by L. Zygadlo (1978) and the OSDA/State/EPA Assessment
Report (1978). Th^ values for the estimated percentage of'crops treated with
EDB, if all DBCP uses are cancelled, are based on the portion of D3C? uses for
which EDB is an alternative pesticide. The calculated dietary burden (DB) per
day per person is derived from the calculation:
DB(ng/kg/d?y) » ppm Residue x % of the Human Diet x
100
kg Diet x % Crop Treated
kg Body Wt 100
As indicated in Table 8, the estimated average daily intake of EDS from
residues in crops at current use levels is 2.59 x 10 mg/kg per day. If it
is assumed that 100% of the crops bear EDB residues, the estimated dietary
burden (DB) is 4.1 x 10 mg/kg per day. This latter figure is appropriate
if an individual eats 100% treated crops.
Site preparation for fruit tree planting, an additional registered preplans
use of EDB, is not listed in Table 3. This is because no detectable residues
have been found in the fruits, and also because the Agency believes that it is
extremely unlikely that this fruit would contain residues, due to the high
volatility of EDB coupled with the many years between EDB application and first
fr^uit harvest.
b. Postharvest Fumigation of Stored Grains
Grains are usually treated post-harvest to prevent insect infestation.
Liquid mixtures of organic solvents such as carbon tetrachloride (CT), ethyLene
dichloride (EDO, and/or carbon disulfide (CS_) are commonly used for this
purpose. SDB generally constitutes inthe range of 1% to 9% of the weight of
the lioTiid mixture. A mixture of chemicals is used because ED3 alone would net
penetrate sufficiently to the bottom of the storage bin. CT is an effective
-32-
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Table a
Calculated dietary burden (CD) of tXB residues in the human diet resulting from U>e noil funtgatlon uses.-
LJ
I
Crop
Asparagus
Utocooll
Carrot a
Cauliflower
Com, sweet
Cotton
Cucuiitoers
Egyplant
latluca
Lima Beana
Melons
Okra
Pa ran i pa
teanuta
tempera
Pineapple
Kjtatoea
$JUaSh
Strawberries
Sweet Potatoes
'Juiitdtoea
Crop
Ibleranoes
of
Inorganic
Bromide
Icon Soil
Incorporation
(Ppm)
10
75
75
10
50
25
30
50
30
5
75
50
75
25
30
40
75
50
5
50
50
Haxiuun
Expected
Residue
of EDO
Jppw)
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
t of diet
matte up of
Currently
Treated
Cropa
HfcUL
9.5
21.0
3.2
Ntcr.
0.2
28.0
1.4
0.2
45.0
11.0
71.0
NBGI.
0.1
NBGL.
27.0
1.1
MflGL
4.4
5.4
6.8
Hood
Factor
of diet
0.14
0.10
0.48
0.07
1.43
0.15
0.71
0.03
1.31
0.19
2.00
0.07
0.03
0.36
0.12
0.30
5.43
0.03
0.18
0.40
2. 07
CO If all of
Crop Consumed
Dears Residue
(ing/kg/day)
3.50 » 10~n
2.50 x 10 ~*
1.20 x 10~'
1.75 x 10~"
3.58 x 10 '
3.75 x 10 *
1.78 x 10"'
7.50 x 10 ,n
3.28 x 10 ""
4.75 x 10 "
5.00 x 10"'
1.75 x 10 a
7.5 x 10 *
9.00 x 10 °
3.00 10 „
7.5 10"°
1.36 10"*
7.50 10~*
4.50 10""
1.00 x 10" '
7.18 x 10-7
Estimated ECB
at Current
Due tevel
{wq/kg/fay}
0 -9
2.38 * 10 a
2.52 x 10_d
5.60 x 10 1U
0 -a
7.50 x 10 "
4.97 x 10 "
1.05 x 10 |!J
6.55 x 10 *u
2.14 x 10~"
5.50 x 10 ~"
1.24 x 10 °
0 ,,
9.00 X 10~"
o a
2.03 x 10 °
1.49 x 10 U
0 „
1.98 x 10~"
5.40 x 10 B
4.38 x 10-8
Total
4.1
10
.-6
2.59 x 10
r7
05
CO
-------
164
"carrier" and EDC is added to the mixture to create the proper vapor pressure.
A typical example of a commodity funigant is Dowfune E3-5, which contains CT,
EDC, and EDB in 63:30:7 proportions.
The data available to the Agency demonstrating residues in EDB-treated
grains are taken from a variety of published papers which report a wide range
of SOB residue levels. This broad range results from numerous factors,
including the type and condition of grain, construction variation in storage
bins selected, EDB application methods and rates, aeration and sampling
techniques, and other related factors. Table 9 summarizes the ranges reported
in the available studies*
Table 9
EDB residues (ppm) Reported in Fumigated Grains *
Aeration Period (Weeks) after.Fumigation
Grain 0 1 4 13
Wheat 12-1500 1-240 5-33 0.6-5.3
Corn 37-1565 21-61 2.5-531 0.3-3.5
Sorghum <1-5.7 14-45 2.1-15 0.9-3.5
Barley 2.2-6.3 1.-2.2 0.9-1.9
Rye 20-32
Oats 10-15 "several weeks after fumigation"
* (Worthington, 1978)
In spite of the wide variation in values reported, a consistent pattern of
decline, which will be discussed later in the text, is apparent from the daca
presented in Table 9.
Cf the grains for which EDB is registered as a fumigant, only wheat and
rice make up appreciable portions of the human diet. Wheat forms by far the
larger portion of the human diet than does rice: 10.36% for wheat and 0.55%
for rice. Therefore, persistence of SOB in wheat is expected to have a much
greater impact on the human- diet (Holder, 1980). Accordingly, the Agency's
analysis will focus on EDB residues in wheat, flour and bread.
It is important to note, however, that human dietary exposure can result
from the use of SOB on other grains and rice. Corn oil, corn aeal, corn
cereals, othar grains, and rice can contain residues of EDB as a result of the
fumigation of stored corn, although most of the stored corn fumigated with EDB
is used as livestock feed (DPRA, 1973). The Agency recognizes that these other
uses could result in secondary contamination of the human diet through residues
of EDB in neat, milk, rice and other products. However, the Agency has no data
to support or dismiss this hypothesis, and therefore considers it to be a data
-34-
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FIGURE I
TIME-LINE OF WHEAT AND WHEAT
BY-PRODUCT DISTRIBUTION WITH EXPECTED
TIMES FOR EDB FUMIGATION
-ON FARM STORAGE
1 Ynnr
8 rr.y.
I
(average)
i
CO
en
I
r,ob*.;x
*
-OFF FARM-
STORAGE
PROCESSING-
^. COMMODITY
\ DISTRIBUTION
1 mo.
1 wk.
JT""1
i.nu
GRAIN
SALE
HUMAN FOOD
'Broad
Cereal*
PreUnls
Noodles
Cookies
.Cakes
05
Constimptloit
As Tort of
Dally Dletnry
Intnkn
(Along with nosldiies?)
ANIMAL FEED
GRAIN EXPORTED
-------
166
gap. The presence of SDB residues, resulting from fumigation of these other
commodities, would increase the estimated SDB dietary burden for its general
use as a fumigant for stored grains•
Because residues of EDB entering the human diet from its use as a funigant
of stored wheat appears to dwarf its use as fumigant for all other grains, the
Agency has focused its efforts on estimating the quantity of EDB contained in
fumigated wheat and wheat products. The quantity of EDB in wheat, flour and
bread varies considerably as a result of variations in the amount of EDB
applied to stored wheat, duration between application and final use of product,
type of storage facility used, and numerous other considerations. In order to
determine the amount of EDB entering the human diet as a result of these
registered uses, the Agency has considered all the available data on residues
of EDB in wheat, flour and bread, obtained additional residue levels on these
commodities through in-house studies, and developed several mathematical models
which estimate expected EDB residues in these commodities at various points in
movement through commerce.
Figure I (Holder, 1980) illustrates the typical movement of a shipment of
grain through commerce. The top line indicates the general areas through which
grain moves. Below this line are the Agency's estimated average periods for
which the grain is held at each locus in commerce; the occurrence of SDB
fumigations which the Agency has determined will be applied during the grain's
movement through commerce; and a chronological list of the commerce areas
through which the grain moves. As indicated in Figure I, the principal methods
of grain distribution are export, animal feed, U.S. mills where grain is made
into flour, and U.S. bakeries where flour is further processed to various baked
goods•
The fumigation schedules shown in Figure I were used by the Agency (Holder,
1980) to estimate the concentrations of EDB in wheat and wheat products at each
major point in its movement through commerce.
In addition to these time estimates, the Agency (Holder, 1980) developed
three mathematical models (using results from laboratory studies) of the loss
of EDB residues from wheat, wheat flour, and baked goods following post-harvest
application of EDB. Using the schedule shown in Figure I, the Agency (Holder,
1980) calculated the "probable" concentration of EDB.in bread to be 0.07 nob,
from which the resulting dietary burden of 1.8 x 10 mg/kg/day was estimated.
This same procedure was used to develop a "realistic worst case" estimate
of the concentration of EDB at each point in commerce, and the dietary burden
which would result from these concentrations. Using the same residue loss
curves (RLC), but assuming a maximum application rate of SDB of 7.2 lbs/1000
boishels (instead of an average of 5.1 lbs./1000 bushels) and minimum treatment
to market intervals, the Agency estimated the residue levels of EDB in bread
and baked goods to be 31 ppb and an associated dietary intake of 3.3 x 10~3
mg/kg/day.
c. Fumigation of Grain Milling Machinery
In addition to residues of EDB that occur in wheat and wheat products as a
result of grain storage fumigation, residues in many wheat products also result
from the use of EDB in spot application to flour mill machinery and as a
general space fumigant in these mills. The Agency has evaluated the three
known studies (Wit, 1969, 1977, 1973) which have investigated the contribution
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167
of flour mill and machinery fumigation to SDB residue levels in wheat flour and
baked breads (Holder, 1980). These studies generally involved sampling for SDB
concentrations in incoming wheat, processed flour, and bread baked from that
flour* Each of these sets of samples was taken, at various tiaes after spot
fumigation.
Because the EDB concentration in the incoming wheat varied greatly from one
study to the next, it is difficult to draw parallel conclusions from these
three studies. The first two studies demonstrated that incoming washed wheat
contained EDB, and that the resulting flour absorbed EDB from the spot-
fumigated equipment (Holder, 1980).
In the Agency's opinion (Holder, 1980) the third and most recent study had
such high levels of SDB in the incoming wheat that it probably "overshadowed
any pick-up of SDB residues from the milling machinery due to spot fumigation."
However, this study did show an increase in EDB residues in flour and bread up
to 3-4 hours after spot funigation. Using a time-weighted average of the
differences between input wheat and the flour derived from the wheat, the
Agency estimates that an average of 3 ppb of EDB persists in bread as a result
of spot fumigation (Worthington, 1978). In the absence of the quantity of
wheat flour processed annually through mills where EDB-treatnient was used, the
Agency has assumed that all flour mills fumigate with EDB. Using the residue
level of 3 ppb, the Agency (Holder, 1980) estimates the dietary burden from
spot fumigation for all wheat by-products to be 0.76 x 10 mg/kg/day,
assuming all wheat by-products are equally contaminated with EDB.
Combining the dietary burden (OB) obtained for spot fumigation with the DB
estimates for EDB used on stored grain, the Agency proj ects that the total
contribution to dietary burden from residues in wheat and flour ranges from
0.24 x 10 to 4.1 x 10 mg/kg/day for all wheat fmigations (Holder,
I960).
In addition to these derived dietary burdens for all SDB fumigations, the
Agency (Holder, 1980) has summarized data on residues of SDB measured in breads
made with wheat treated with EDB. A total of 57 samples from 5 Independent
studies yielded an average observed residue level of EDB in bread of 28 ppb
with a corresponding dietary burden of 4.1 x 10 mg/kg/day.
The Agency has efforts underway to obtain additional data on residues as
they actually occur in commerce. The Benefits and Field Studies Division of
OPP, in cooperation with the USDA's Federal Grain Inspection Service, has
analyzed flour samples obtained from several of the USDA's programs for
distributing flour to domestic charity programs, including the School Lunch
Program (Marshall, 1980). Preliminary results of these analyses for SDB
(Bbntoyan, 1980) confirmed EDB residues in all of the samples analyzed in the
first phase of this study.
Because this DB is derived from actual measurements of EDB residues
observed in bread, it includes SDB residues resulting from both spot fumigation
of grain milling machinery and grain storage ftmigation.
It is-worth noting the markedly good agreement between the DB of
4.1 x 10 determined from actual bread samples and the projected maximum DB
of 4.1 x 10 . derived from the assumptions and calculations discussed above
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168
(Holder, 1980). Thus, the Agency concludes that the total dietary burden
resulting from EDB fuaigation of wheat in storage and of flour machinery is
best estimated from the data collected from actual bread samples, which is 4.1
x 10 mg/kg/day.
For an "average" 60 kg individual in the U.S., this dietary burden
translates into 2.5 micrograms of EDB consxmed per day from the fxanigation uses
of EDB on stored grains. As discussed above, only funigated wheat and wheat by-
products were considered. The estimated dietary burden may slightly
underestimate the actual DB resulting from the commercial use of EDS to
fvanigate stored grains. Considering the evidence currently available to the
Agency, 4.1 x 10 mg/kg/day is the Agency's best estimate of the dietary
burden resulting from all EDB fumigation.
d. Quarantine Fumigations
Several agricultural fruit and vegetable commodities are regulated by
federal and interstate quarantines. These regulations were enacted to protect
the importing state from the introduction of new insect or disease pests.
U.S. quarantine treatments are legally mandated by authority of the Plant
Quarantine Act of 1912 as amended (7 D.S.C. 151-167) and the Federal Plant Pest
Act (7 U.S.C. iSOaa, iSOjj) through quarantine administrative instructions, and
regulations. The U.S. Department of Agriculture's Animal and Plant Health
Inspection Service (APHIS) is responsible for carrying out these mandates.
DSDA regulations require treatment of imported commodities and of certain
commodities transported out of quarantined regions (Table 10).
Table 10
U.S. Quarantine Requirements for. EDB Treatment
Regulation Commodities Exporting Countries
7 cm 318.13-45 bitter melons, bananas, Hawaii
litchi nuts, cucumbers,
papayas, pineapples,
cayenne, string beans,
zucchini squash
7 C?R 318.58-2d mangoes Puerto Rico
7 CTR 319.56-2c oranges, tangerines, Mexico and
grapefruits certain Central
American countries
7 CFH 319.56-2J mangoes, plums Mexico,
Guatemala
As a consequence of the U.S. quarantine requirements, EDB is. registered =is
a commodity fumigant for post-harvest control of insects infesting citrus,
tropical fruits (including mangoes, papayas, litchi fruit and nuts, and
guavas), pineapples, bananas, cherries, plums, peppers, cucunbers, string
beans, and zucchini squash. For many of these commodities, SDB is the only
fumigant authorised by the USDA regulations. In addition, certain states also
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169
require fumigation of interstate transported commodities. In California, the
State Administrative Code (section 3252) restricts importation of several
citrus fruits from Puerto Rico and Florida. These commodities may only be
received in the Stats after being fumigated at the point of origin in
accordance with APHIS reaulations.
EDB treatments are carried out in fumigation chambers as specified in
Quarantine 13 (7 CFR 318.13), Quarantine 58 (7 CTR 318.5S), and Quarantine 56
(7 CFK 319.56). Quarantine specifications call for the use of technical grade
EDB of at least 97% purity, which is typically introduced into the fumigation
chamber in the liquid state onto a home-variety electric frying pan 'for
volatilization. This is the method used in Florida. An alternate method, used
in Texas, involves the dripping of liquid EDB in front of a high speed fan.
Because of the high density of EDB gas (more than six times heavier than air),
forced circulation within the chamber is also required for volatilized EDB.
The exposure period for both methods is two hours from the time all the
required EDB has entered the chamber.
Over 99% of the 83,500 pounds of EDB used in 1977 for quarantine purposes
was applied on citrus and tropical fruits (EPA, 1979). The remaining amount of
EDB, less than 850 pounds, was used on an estimated 750,000 pounds of
miscellaneous fruits and vegetables which constitute only niniscule percentages
of the total U.S. production of each of these commodities (Zygadlo, 1978). The
Agency recognizes that some SDB food residue exposure can occur from these
minor uses. However, the national dietary burden which results from these
minor uses is negligible and insignificant in comparison with that expected
from EDB fumigation of citrus and tropical fruits (Table 13). Thus, these
minor,uses are not discussed further, although a maxiinvsn dietary burden of IS.8
x 10 mg/kg/day (Holder, 1980) could be expected if 100% of these minor
crocs were fumigated with EDB or an individual ate 100% of SDB-treated food.
There are some monitoring studies available on the residues of EDB in
various fruits and vegetables resulting from quarantine fumigation with EDB.
The studies show that, while EDB penetrates these commodities more rapidly and
completely than it does grains, it also dissipates more rapidly from them
(Worthington, 1973).
These limited data were compiled by the Agency (Worthington, 1978) to
estimate the average EDB residues occurring in citrus and tropical fruits one
day after fumigation. The Agency (Worthington, 1978) estimated the average SDB
residues occurring in citrus and tropical fruits one day after fumigation to be
8.0 ppm and 5.0 ppm, respectively. Using these data and a residue loss
equation, derived from the longest half-life time of two days, residues it any
tinra (t) can be calculated. See Table 12 for calculated results.
Subsequent to these estimates the Agency obtained data from the State of
California (Maddy, 1979b) on residues of EDB found in citrus and tropical
fruits collected in 1979 from wholesale produce markets in that state. These
fruits had beer, fumigated "to comply with OSDA quarantine directives prior to
entry into California." The Agency (Worthington, 1979) has evaluated these
data, and summarized them in Table 11.
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170
Table 1 1
Measured EDB Residues in Fruits Obtained from California Wholesale
Produce Markets
Fruit Period after Number of Range of EDB Average ED3
Fumigation Samples Taken Residues Residue Level
( days ) ( ppm } ( ppm )
Papayas 3 to 16 24 0.13 to 1.24 0.69
Oranges 3 or 16 9 0.06 to 6.35 r. 37
The Agency (Worthington, 1979) has analyzed these data to determine if they
support its estimate that one day after fumigation the EDB levels in citrus and
tropical fruits are 8.0 ppm and 6.0 ppm, respectively, and has concluded that
they do support these estimates. 3y taking the obser~ 3d residue levels and the
duration of these levels after fumigation, the Agency (Worthington, 1979) has
extrapolated to one day after fumigation using dissipation equations. These
results generally cluster around the SDB concentrations one day after
fumigation as previously estimated (Worthington, 1973).
In order to calculate the most likely residue levels occurring in these
commodities at the retail market, the Agency (Panetta, 1979) has obtained
specific estimates of both the minimum and the average treatment-to-market
intervals.
These time intervals and the initial residue levels were put into the
residue loss equation discussed above to obtain estimates of residue levels in
citrus and tropical fruit at the retail market (Table 12).
Table 12
Estimated EDB Food Residues Resulting From Required Quarantine Fumigation
Commodity Estimated Initial Estimated Market
Residue Level Residue Levels
(ppm) a/ (ppm) b/
Maximum" Average"
Citrus
Trooical Fruits
8
6
1.42
0.76
0.425
0.32
a/ Maximum residue levels assume a minimum treatment- to-market interval
of 6 days for citrus and 7 days for tropical fruits, b/average residue levels
assume 7 and 9.5 days, respectively (Holder, 1980).
The last t-wo steps in calculating the DB for the U.S. population resulting
from EDB fumigation of citrus and tropical fruits are to multiply the estimated
residue levels from Table 12 by the percent crop treated, and multiply this
product by the food factor (i.e., % of human diet which the commodity
represents). The percent crop treated and consumed in the U.S. was first
estimatad to be 1.7% for citrus and 72% for tropical fruits (Sygadlo, 1978).
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171
The estimate of the percent of crop treated for citrus was amended (Luttner,
1980) to 2.6% because the original estimate did not include citrus which is
fumigated and imported to the U.S. The estimates of the food factors are 3.3%
and 0.03% respectively for citrus and tropical fruits.
Accordingly, che following DB estimates have been calculated:
Maximum DB Average DB
( mg/ kg/ da y) (mg/ kg/ day)
Citrus 3.5 x 10~ 1.05 x 10~5
Tropical Fruits 0.41 x 1 0~5 0.17 x 10~5
e. Control of Wax Moths in Beehives and
Associated Equipment
There are two Federally registered products containing EDB for controlling
the wax moth (Galleria mellonella) in stored honeycombs. [The label of one
product states that it is to be used on "...empty combs and ampty hives" (Reg.
No. 10092-1), while the other label gives directions for use, "When bee combs
and/or hives are stored for the winter..." (Reg. No. 5785-46)]. No tolerances
have been established for either organic EDB or the inorganic bromide ion
residues for the use of EDB on honeycombs, because both registrations were
considered nonfood uses. Although these labels do not specifically prohibit
the use of EDB on honey or comb wax, it is not normal practice among beekeepers
to do so. There are no known data on the potential for indirect EDB
contamination through translocation to edible honey or beeswax as a result of
fumigating stored comb-bearing frames or comb foundations. The Agency believes
that no residues in honey are likely to result. Consequently, this registered
use is not expected to contribute to the dietary burden of EDB.
f. Other Registered Uses of SDB
The remaining registered uses of EDB involve non-food uses and are not
included in the dietary burden estimates. These uses include vault fumigation
of stored clothing, structural termite control, control of bark beetles in
coniferous trees, quarantine treatment of regulated articles for Japanese
Beetle (including soil, plants with roots, and grass sod), and parasitic
nematode control (including nursery plots, greenhouses, and potting soil).
g. Summary of SDB Dietary Exposures
Resulting from Registered Use Practice
Table 13 is a summary of the daily dietary burden resulting from each of
the food uses of EDB. _This table shows the dietary burden at current use
levels to be 1.21 x 10 rag/kg/day and 6.31 x 10 mg/kg/day if 100% of the
crops on which EDB is used were treated. Included in this table are the
relevant input data used to develop the dietary burden at current use levels.
These include the average treatment-to-market interval, estimated EDB residue
level at the time of entry into the human diet, the percent of total human diet
made up by the given commodity, and the current percent of the commodity which
is treated with ZDB. As shown in this table, fumigation of stored grains and
post-harvest fumigation constitute over 90% of the dietary burden which results
from registered EDB use practices. The table does not include soil fumigation,
where no residues have been found.
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table 13
Total Dietary burden (DB) of EDB residues in the human diet resulting fro* all commodity fuaigation uses*
Average
Treatment to
Market Time
(days)
Commodity
1.
2.
3.
4.
5.
6.
7.
a.
9.
10.
11.
All
Grain Products
(Bulk Fumigation)
Grain products
(Spot fumigation)
Tropical Fruits
Citrus
Cherries
Pluma
Peppers
Cucurbits
Bananas
String Beans
Pineapple
218
1.0
9.5
9.5
5
5
5
5
5
5
5
Eat. Residues
at Time of Entry
into the
Ikman Dietary
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173
2. Inhalation and Dermal Exposures
All registered pesticidal uses of SDB may result in inhalation exposure.
Applicators may be exposed during transfer, mixing, loading and actual
application operations, calibration and repair of equipment, and reentry into
fumigated structures or fields. Other workers noc involved in the actual
application of SDB may be exposed, including those working at or near grain
storage sites and mills which have been fumigated, citrus quarantine fumigation
stations, apiaries where fumigation has been used to control wax moths in
beehives, and fields fumigated with SDB. The general public is not likely to
experience significant inhalation exposure, although seme exposure may occur in
areas near quarantine fumigation stations, bark beetle control oper.ations, and
structures which have been fumigated for termite control. The major use
patterns (for which quantitative exposure data are available) involving SDB
inhalation exposure and risk estimates for specific populations at risk are
presented in the following discussion. They are: a. preplant soil fumigation,
b. citrus fumigation, and c. grain mill fumigation.
a. Exposure from Preplant Soil
Fumigation
Ethylene dibromide is applied as a liquid pre-plant soil fumigant from
tractor-mounted tanks or cylinders, using chisel injection or plow-sole nethorfs.
The injection chisels or plow soles normally remain in the earth as the
tractor moves across the field, and are removed only when the applicator turns
the tractor around at the end of each pass. A small quantity of EDB may be
released above ground when the chisels or plow soles are removed.
When EDB is applied with chisels, a float, cultipacker or roller is dragged
behind the chisels to seal the soil. When plow-sole applications are used, the
chemical is metered in front of the plow on the soil surface and immediately
covered with soil by the plow behind and to the side of the treated area. Less
than 5% of EDB is applied using the plow-sole method. However, in the
preparation of pineapple fields, SDB is soil injected under a. plastic mulch
which prevents rapid volatilization.
Tractor operators and other applicator personnel may be exposed through
volatilization of EDB before and/or after the sealing of the soil. In
addition, exposure may also result from the calibration, cleaning or repair of
equipment, from equipment failure, and from transfer and loading operations.
SDB is generally applied by open system operations, in which the pesticide
aiust be transferred from 30 or 55 gallon drums by hand, powered pumps or
gravity flow devices into tanks mounted above the injection chisels. There is
potential for applicator exposure by inhalation of vapors and skin contact with
the liquid during these open system transfer operations.
There is also a closed system method of transfer, in which SDB Is fad to
the chisels or plow soles from cylinders prepackaged with valves and diptubes,
or containing a convenient orifice for attachment of suction tubes. The Agency
is currently studying (but has not yet determined) the effectiveness of closed
system technology in reducing worker exposure for many chemicals, including SDE
(Hittelman, 1980).
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174
The time duration for transfer operations and application varies, but it is
roughly 10 minutes (0.17 hrs) for each transfer operation and 1.75 hrs for each
application operation (Mittelman, 1980).
The Agency has estimated the annual exposure duration for total soil
funigation operations by site. These estimates are presented in Table 14. The
estimates assume that transfer operations occupy 10% of the total application
time.
1) Inhalation Exposure
There are relatively few measurement data regarding applicator exposure to
ECB. The only sources of information are reports by the California Department
of Food and Agriculture (Maddy, 1979c), Dow Chemical's Industrial Hygiene
Laboratory (Vaccaro, 1976), and the Great Lakes Chemical Corporation (White and
McAllister, 1977). The Dow and Great Lakes studies were submitted as parts of
the rebuttal responses of these two manufacturers (Rebuttal IIos. 78 and 3C).
These studies have been analyzed by the Agency (Mittelman, 1980).
Column 1 of Table 14 identifies the soil fmigation operation or location
for which EDB air concentration was measured. The only measurements Listed arp
those in which individual activities were monitored, in order to properly
assess worker exposure. Air samples were taken during application alone (with
open and closed cab), during transfer operations, while respiratory equipment
was in use, and at sites on the treated field during application and up to 48
hours afterward.
The average EDB concentration measured in air (milligrams of EDB per cubic
meter of air) at each of the sampling sites is listed in colunn 2. The use of
closed cab tractors and closed transfer systems apparently did not reduce
exposure to applicators involved in these studies; however, closed system
research is currently being carried out, and insufficient data exist at this
time to evaluate the 'future impact of closed cabs and transfer systems on
applicator exposure.
The range of concentrations measured in each location and the nunber of
samples taken are listed in columns 3 and 4. The greatest range of
concentrations was measured during application activity in an open cab tractor
where the exposures ranged from 0.008 to 4.75 mg/m . No range is listed for
closed system transfer operations because a single sample was taken.
2) Dermal Exposure
The CDFA study (Maddy, 1979c) included measurements of SDB levels in hand
washings taken from tractor drivers. The five samples taken ranged from 0.52
to. 30.90 ug, with an average of 3.38 ug. Actual dermal contact incurred during
transfer of EDB was not measured; however, the Agency assunes that the actual
dermal contact incurred during normal operations will be at the same or higher
levels than those measured from the hand washing samples because some EDB is
expected to have evaporated or penetrated the skin (Mittelman, 1980).
3) Combined__Inhalation and Dermal
Exposure
The Agency (Mittalman, 1980) has estimated tor.al inhalation and dermal
exposures for private (non-professional) persons who both apply and transfer
-44-
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Table 14
A
in
Exposure Situations Average
Application/Closed cab
Application/Closed cab
charcoal filtered intake
Application/open cab
Transfer operation/open
system
Transfer operation/closed
system
Area samples at field level:
(A) During application
(B) 24 hrs post-application
(C) 48 hrs post- application
concentration
in air
(mg/m3)
1.66
1.27
0.81
3.03
5.60
0.17
0.02
0.07
Range Number of
(mg/
-------
176
SDB during soil fumigation. These,estimates, contained in Table 16, ass one a
constant respiratory rate of 1.2 m /hr for light physical activity (No heavy
activity breathing rates were used), a constant ambient air concentration
(average of monitored values), and a range of exposure duration (see Table
15). Exposure estimates have been made for each use site (colunns 1 and 2).
The total respiratory intake of EDB (milligrams per year) is presented in
colunn 3 as the sum of exposures resulting from transfer and application
operations. It is assuned that the applicator performs the transfer operation
himself; 100% retention of inhaled EDB is also assuned. Total respiratory
intake has been calculated in the following way, using data given for peaches
as an example:
Inhalation Rate x (Transfer Exposure +• Applicator Exposure) - Total Exposure
For peaches: 1.2 m /hr [(0.06 hrs._x 3.03 mg/m ) •*•
(0.54 hrs. x 0.81 mg/ra )] » 0.7 mg.
Total estimated dermal exposures are presented in column 4. An average
dermal exposure value of 4.53 micrograms per hour is assumed (Maddy, 1979a).
This value is based on EDB levels in water from hand washings, and assumes chat
the hand contact is the largest source of dermal exposure. Therefore, the
dermal exposure estimates given here probably underestimate actual total dermal
exposures.
One hundred percent of the EDB remaining on the skin is expected to be
absorbed, based on data for DBCP, a chemically similar compound (Mittelnan,
1980). Total estimated dermal exposure has been calculated by multiplying
average dermal exposure by the duration of exposure. The following example,
for peaches, uses figures from Table t5.
Dermal x (Transfer -*• Application) =* Total Exposure
4.53 ug/hr x (0.06 hrs. + 0.54 hrs.) » 0.003 mg
The total estimated annual exposure (milligrams per year) is listed
according to use site in colunn 4. It is expressed as the sun of the
inhalation and dermal exposures for each use site. Assuming a 70 kilogram
applicator, the maximum estimated exposure to EDB is experienced by pineapple
applicators and transfer-operators. The total estimated annual exposure for
this use site ranges from 303.3 to 532.4 mg/yr.
Commercial (professional) applicators' exposures are unknown, but the
Agency (Mittelman, 1980) estimates that the duration of exposure of the
approximately 25 professional applicators nationwide is roughly four times as
long as that of the estimated 13,200 potentially exposed private applicators,
based on data received from Great takes Chemical Co. (1977).
The CDFA (Maddy, 1979c) and Dow (Rebuttal Ho. 78) studies reported airborne
concentrations of EDB in the breathing zones of applicators while respirators
were in use. Based on the data from these studies, the Agency (MitteLman,
19SO) concluded that the use of respirators can effectively reduce inhalation
exposure by a factor of 14 for half-face and 24 for full-face respirators, but
the use of closed tractor cabs is not necessarily effective, based on current
data that demonstrate higher exposures in closed cabs than ir. open cabs.
-46-
-------
Tobta IS Eutl«k»ttd mutual dutat Ion of expouure to trtl to Boil fumigation workera (I)
Annual iteration of exposure
eutloiated nuotxir of exposed
Hke Transfer Application
teaches
Ibbacoo
fleanuts
(HA, AIA,
Nne^lea
Wstja tali lea
Sweet
potatoes
Irish
potatoea
Cotton'TCA)
Cotton (All,
GA, H!i, NCI
Cltnia (pre-
plont)
.06 0.54
1 - 2.5 9 - 22.5
1.2 10.4
24.5 - 43 220.5 - 387
1-5.2 8 - 46.8
0.2 - 0.3 1.8 - 2.7
0.4 - 0.7 3.6 - 6.3
JO 90
2-6 IU - 54
2.5 - 3.2 22.5 - 2U.8
applicatora (private only)
670
10,800 naxiiim
35
45
414
650
150
25
410
1
Citrus (bur-
rowim nuuia-
41.6
uunt
374.4
duration
of 52 man day a)
unknown
(T) MffteTman, T9BO
12) tor putpuaea of eatiwating expouuro, tlie Ajency lias aiiuiuiud a
transfer tturation of 101 of total e*i
-------
Table 16 Total estimated annual exposure to M)B for prlvato applicators/transfer operators during soil fumigation. (I/)
Uaa
Bite
Peaches
Tobacco
Peanuts
Pineapples
^ Vegetables
DO
1 Sweet
Potatoes
Irish
Potatoes
Cotton
(CA)
Cotton
(AR, OA,
M3, NC)
Citrus
(preplant)
Citrus
(burrowing
nematode
containment
program)
Total respiratory Intake of KDD (mg/yr)
Transfer Application Total
0.2
3-6-9
4.3
88.2-154.8
3.6-18.7
0.7-1.1
1.4-2.5
36
7.2-21.6
9-11.5
149.8
0.5
8.7-21 .8
10.1
213-9-375.4
8.7-45.4
1.7-2.6
3.5-6.1
87.3
17.5-52.4
21.8-27.9
363.2
0.7
12.3-30.8
14.4
302.1-536.3
12.5-64~.l
2.4-3.7
4.9-Q.6
123.3
24.7-74
30.8-39.4
513
Total estimated dermal Total exposure
exposure (mg/yr)(2/) isB/Vt
0.003
0.05-0.125
0.058
1.2-2.2
0.05-0.26
0.01-0.015
0.02-O.035
0.5
0.1-0.3
0.125-O.16
2.06
0.7
12.4-20.9
" " " ' " ' 14.5
303.3-532,4
2.4-3.7
4.9^.6
123.8
24.8-74.3
30.9-39.6
515.1
(aggregate exposure)
TI
(2
IT KfA. Hittalmon, 19Gb. Auaumptlona are discussed In tho text.
2) Itaaed on average dermal expoaiire of 4.53 ug/hr (Hoddy, 1979 ).
00
-------
179
4) Summary of Preplant: Soil
Fumigation Data
The data ir.dicata that exposure to ZDB results from all soil f-jnigation
operations. The highest applicator exposures occur during transfer or loading
operations. Exposures also result from broken hoses or other delivery lines
and practices such as lifting chisels out of the ground while turning at the
end of a row or passage and knocking off caked soil or organic debris from the
chisels (Mittelman, 1980).
Data are not sufficient to estimate annual exposure resulting from dermal
contact with EDB during soil funigation. However, the Agency has collected
data and estimated that EDB levels on the hands of tractor drivers range from
0.003 mg/yr for peaches to 2.15 mg/yr for pineapple (Mittslman, 19SO).
More data are needed about the use of closed tractor cabs and closed
transfer systems before their effectiveness can be evaluated. The Agency has
been receiving comments on current efforts to develop a closed transfer
system. SPA encourages such efforts.
b. Exposure from Citrus Fumigation
Ethylene dibromide is used in quarantine fumigation programs administered
by the Animal and Plant Health Inspection Service (APHIS) of the U.S.
Department of Agriculture (USDA). Target pests include several species of
fruit flies which may infest various fruits and vegetables exported from the
U.S. or shipped from state to state.
Quarantine fumigation of citrus is carried out at commercial facilities in
all major ports of entry in the U.S.. In Florida, the Stats Department of
Agriculture conducts quarantine fumigation at its own facilities.
The Agency has obtained data on inhalation exposure to ZDB associated with
quarantine fumigation of grapefruit in Florida (Mittelman, 1980). Two large
fumigation centers in Wahneta and Fort Pierce, which operate under a
cooperative program between the USDA and the State of Florida, and a Tampa
warehouse were selected for study by EPA to investigate worker exposure to
EDB.
The fumigation centers consist of stations where whole truckloads of citrus
are fumigated in large drive-in chambers. The Wahneta station has twelve
chambers and i-.he Ft. Pierce facility has sixteen. The individual fumigation
chambers are designed to accomodate truck trailers loaded with approximately
1000 boxes of pre-packed citrus. After the chamber is loaded and clc:2d, a pre-
determined amount of liquid EDB is dispensed into an electric evaporator to
start the two-hour fumigation. After the fumigation has been completed, the
EDB is exhausted from the chamber into the outside atmosphere, and the trailer
is hooked up to the tractor rig for transportation to dockside warehouses; most
frequently at the Port of Tanpa.
Several groups of people may be exposed to SDB during fumigation
operations: fumigation center employees; truck drivers, when they enter the
chamber to hook up the tractor-trailer rig, and later when they open the
trailer doors to unload fruit at the warehouses; warehouse and dock workers,
who unload fruit from the trucks, sort and stack the fumigated boxes in the
warehouse, and move the boxes to ships for loading. There is also some
-49-
418-574 0-83-13
-------
180
potential for exposure of people who live, work or drive in the vicinity of
fumigation operations, from EDB exhaust in the atmosphere and the venting of
SD3 from departing trucks.
1) Data or. Applicator Exposure
The Agency has assessed inhalation exposure data from a nunber of studies
on fumigation station workers at Ft. Pierce and Wahneta, Florida and warehouse
workers at Tampa, Florida (Mittelman, 1980). Estimates of the annual
inhalation exposure to EDB for these occupationally exposed groups are
presented in Table 17.
The Agency (Mittalman, 1980) calculated the average annual Inhalation
exposure to EDB in milligrams per kilogram per year, assuning a 70 kg worker,
in the following manner:
Exposures
Wahneta-Indoor Operations
Avg. Concentration Breathing Hrs./ Working
of EDB rats day Days/yr.
3 3
0.207 mg/n x 1. 8 m hr x 8.0 x 112 - 70 kg =4.8 mg/kg/day
These calculations assune a concentration of SDB that is based on the
average of all survey samples taken at each site, a moderate breathing rate
(assigning 50% of the work shift is spent in slack activity, and 50% in heavy
activity) a 112-day season at the funigation station, and a 155-day season at
the citrus warehouse.
The figurss in the table indicate that the workers inside the warehouse
apparently experience the highest exposure to EDB. These exposure levels are
estimated to be up to one hundred times the average yearly dose experienced by
fumigation station workers.
Major fumigation treatment operations are also performed in Texas and
Hawaii. However, these operations are slightly different from the method
employed in facilities in Florida. In Texas, EDB is applied by dripping the
compound into a high-speed blower rather than by evaporation. Of the 36 total
facilities in the O.S., there are 25 commercial stations and a nunber of
private operations in Texas. There are no known air sampling data available
from these stations. In Hawaii, the funigation of papayas, bananas, citrus,
Litchi nuts and cucumbers is performed by evaporating EDB from a heating pan.
Treatment operations occur throughout the year. The fruit is hand-carried in
field boxes into and out of the fumigation chambers. High potential for
exposures therefore exist. The Agency estimates that a total of 12 ArHIS and 5
State of Hawaii employees monitor and supervise the funigation activities.
Though measurements using detector tubes have failed to detect SDB levels in
worker space, the limits of sensitivity of these methods are relatively high in
the range of 1-100 ppm, as compared to .008 ppm in Florida measurements
(Mittleman, 1930).
In addition to the personnel employed at funigation stations and
warehouses, other persons are potentially exposed to SDB through quarantine
fumigation uses. At the Wahneta and Ft. Fierce stations and at the warehouses,
-50-
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I
in
Table 17. Inhalation exposure of workers, to H>B at citrus fumigation stations and at a oltrua warehouse
Location fcrkera Concentration of Avg exposure to
H)B (mg/B3) Number of Breathing Hra/day \J Daya/yr 2/ H)B /•»»/i'»/«-t *>
tbhneta
- Indoor operators
Ft. Pierce - Indoor operators
Wahneta
- Outdoor operators
Ft. Pierce - Outd9or operators
Uahneta
- Truckers/Station
Personnel
Ft. Pierce - Truckers/Station
Personnel
Uahneta
Tanpa -
Tampa -
Tanpa •
- Truckers
- Forkllft operators,
Laborers
(inside)
- Forkllft oparators,
Laborers
(outside)
- •Stlcknen*
0.207
0.607
0.406
0.280
0.048 §/
0.092
1.93
8.99
2.36
4.76
14
1
19
2
3
1
2
1
3
2
1 .8m3/hr
1 .6a»3/hr
!.8m3/hr
t.8«3/hr
1 .8a3/hr
1.8a3/hr
t.8m3.hr
1 .8m3/hr
1.8n3/hr
1 .8m3/hr
8 112
8 112
8 112
8 112
8 112
8 112
O.Oa H2r/
a 155^
a 155^
8 155^
4.8
14
9-4
6.5
1.1
2.1
0.4
287
75.3
151 .1
1. lira/day are very variable depending on work load during year. Average 8 hr. work day la assumed hare'.
2. Data from APHIS (1977)
3. Assuming 22 working days a vonth over the period of October 11 through Hay 14
4. Aauualng a 70 kg worker
5. Assuming heavy activity (Spector, 1956).
6. Assuming trucker returns once each day
7. Avg. of 48 monitoring study samples _
8. Including "non-detectable" samples at level of detection (0.003 «g.»}).
oo
-------
182
there are private residences located a short, distance from the station. This
snail non-occupational population may be exposed. Truck drivers transporting
citrus to the Florida chambers are also potentially exposed for several hours
while waiting at the fumigation station, and when entering the fumigation
chambers for short periods of time (approximately 5 minutes) to couple and
uncouple their vehicles. Very little data are available on the levels to which
these populations are exposed.
2) Summary of Exposure Data for Citrus
The data indicate that significant exposures to EDB are encountered by
workers in all phases of quarantine f-umigation operations. The highest
exposures apparently result from warehouse work. However, the limited data
available from Florida fumigation centers indicate that high levels of EDB
occur at these facilities. There are no data available on fumigation
facilities in other states. It appears that there is high potential for
exposure in Texas and Hawaii (Mittelman, 1980).
A number of other people are likely to be exposed to EDB from fumigation
operations. These include truck Drivers and the general population living or
driving near fumigation facilities. Although those living in homes adracent
tofumigatign stations are exposed to very low levels of EDB (.025 ng/m to
0.952 mg/m ) there may be significant numbers of people exposed (Mittleman,
1980).
c. Exposure from Grain Mill Fumigation
EDB is used as a "spot" funigant in grain mills. This use is a-consequence
of regulations of the Food and Drug Administration and O.S. Dept. of
Agriculture which specify maximum acceptable levels of insects or insect parts
in processed foods. EDB is particularly effective in flour milling machinery
and equipment. There are many ledges and obstructions where the product
accumulates, and infestation tends to occur. Proper "spot" treatment of these
critical areas prevents insect growth and reproduction. Typically, a
formulation containing 70% EDB and 30% methyl bromide is used, although a
mixture of 59% EDB, 32% carbon tetrachloride and 9% ethylene dichloride is also
common.
Spot fumigations are performed on flour milling and cereal handling
equipment after running the machinery until it is as empty as possible, leaving
only small quantities of the product trapped in the equipment. The funigant is
typically applied by means of applicator gun injection into holes in the
milling equipment designed specifically for this purpose. Spot f-umigants are
usually applied over a weekend when the mill is shut down and personnel are
away. The fumigation period typically lasts about 24 hours, after which the
mjj.1 is aerated prior to the return of the mill workers. Mill fumigations are
repeated on a 3-4 week cycle in order to interrupt the 4-6 week life cycle of
invading target pests.
In addition to spot fvaigators who apply EDB, personnel involved in opening
the mill and mill workers themselves are also potentially exposed to
substantial quantities of EDB during start-up procedures. In some cases, the
same mill personnel are involved in fumigation, aeration and start-up
procedures.
-52-
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183
1) Data on Grain Mill Fumigator
Exposure
A report commissioned by the Millers' National Federation and prepared by
Industrial Health Engineering Associates (IHEA, 1978) provides the only data
available to the Agency on EDB exposures resulting from grain mill fumigation.
IHEA measured exposure levels of EDB both inside and outside respirator face
masks worn by selected applicators during fumigation operations at five
different mills.
Based on the IHEA data, the Agency (Mittleman, 1980) has calculated a worst-
case exposure for applicators of 50.8 to 59.3 mg/kg/yr. This exposure estimate
assumes that the respirator is not worn tightly against the face or that it is
removed during application, and that there is no rotation of applicators.
Alternatively, with proper use of the respirator and no rotation of
applicators, an inhalation exposure of 4.3-12.5 mg/kg/yr is estimated. The
bases for calculating these figures are presented in Table 18.
2) Summary of Spot Fumigation Data
The IHEA study indicates that exposure to EDB can occur during and after
spot fumigation. The highest levels of EDB were measured during the opening
and start-up operations in grain mills. The data indicate that spot funigators
are potentially exposed and encounter significantly lower levels of EDB when
respirators are properly worn.
Estimated exposures to SDB for workers associated with spot funigation are
presented in Tables 18 and 19. Workers involved in spot fumigation are usually
also mill employees therefore, application, opening and start-up are included
in the inhalation exposure estimate in Table 18. Table 19 presents the
inhalation exposure estimate for those millworkers not involved in funigation.
3) Conclusions
The Agency has reviewed and evaluated all of the available data on
inhalation exposures to EDB. Uses of EDB for which data were available include
soil fumigation, quarantine funigation of citrus, and grain mill ("spot")
fumigation. The populations at risk from these uses of EDB are listed in Table
20. The remaining registered uses of EDB are listed in Table 20 and include
vault fumigation of stored clothing, control of bark beetles in coniferous
trees, -termite treatment, fumigation of beehive supers, and control of Japanese
Beetles and parasitic nematodes. Exposure data were not available for these
uses. Table 21 is a sunmary of the estimated average dose of EDB experienced
by soil fumigation applicators, quarantine funigators and spot fumigators.
These estimates are derived from exposure data which was analyzed by the Agency
(Mittelman, 1980) .
C. Quantitative Assessment of Risk Data
1. Oncoaen ici try
The Agency's Interim Cancer Assessment Guidelines (41 FR 21402) state that
when a chemical is judged to be a potential human carcinogen, the Agency will
estimate its possible impact on the public health at current and anticipated
levels of exposure. The Cancer Guidelines also recognize that the available
-53-
-------
IB. INIIMATIOH EXPOSURE OF SPOT FUMIGATION APPLICATORS TO ETB
I
ui
Job Category tetlvityj/ Duration Average Number of wg/yi Inhalation nj/kg/yt/ inhalation
(Spot fumigation of activity concentration applications exposure 5/ exposure 6/
applicator) (hra) 2/ of EDfl in rlu» , per year per
breathing zone (og/m ) applicator 4/
Range in parentheses V
I a) Proper use
of respirator
b) Rotation of
applicators
II a) Improper use
of respirator
b) rotation
of
applicator
III a) Improper
use of
respl rator
b) No
Rotation
of
appl Icators
Spot
fumigation
Fogging
Opening alone
(aeration)
Opening f
start up
Normal
operation
Spot
firolqatlon
Fogging
Opening alone
(aeration)
Opening t
start up
Normal
operation
Spot
fumigation
Fogging
Opening alone
(aeration)
Opening -f
start up
Normal
Gyration
1.6S
1.2
0.5
i.e
6.2
1.65
1.2
0.5
1.8
6.2
1.6S
1.2
0.5
1.8
6.2
1.6 (level of detection
0.8 - 2.3 n=3)
4.6 (n=l) 1.6 - 4.7 299.1-878.7 4.3 - 12.5
12.8 (1.9-26.9 n=6)
39.9 (30.6-54.2 n=5)
3.8 (level of detection)
17.1 (n-1)
34.2 (n=l)
12.8 (1.9-26.9 n=6) 1.6 - 4.7 474.1-1392.8 6.6 - 19.9
39.9 (30.6-54.2 n=5)
3.8 (level of detection)
17.1 (rvl)
34.2 (n=O)
12.8 (1.9-26.9 n=6) 12-14 3556-4148.7 50.8-59.3
39.9 (30.6-54.2 n=5)
3.8 (level of detection)
00
-------
185
Footnotes for Table 18.
I/ Space fogging with organophosphates or bin fogging with
methyl bromide may occur following spot fumigation with
EDB. Should this be the case, additional exposure to
EDB will occur due to volatilization of EDB from the
machinery. The mill may be opened (aerated) several
hours to a day prior to start up or may be opened and
started up simultaneously (IHE, 1978). Normal operation
involves the typical milling cycle on the first day of
renewed operation.
2/ IHE, 1978. (average of five mills). Values for each
fumigation cycle.
3/ IHE, 1978. Concentrations of EDB are assumed present at
level of detection.
4/ Estimate based on 6-15 applicators/mills (Soyersmith,
1977) and 12-14 applications annually (DPRA, 1978).
If two applicators work together and applicators are
rotated, then each applicator performs 1.6 to 4.7
fumigation cycles annually:
14 applications 12 applications
3 application teams = 4.7; 7.5 application teams = 1.6
5/ Assumption of 100% inhalation retention and 1.8 m /hr
•respiratory rate (Spector,1956) . The same employees may
or may not be involved in all five activities listed.
It is assumed here that the spot furaigator is involved
in spot fumigation, fogging, opening and start up, and
normal operation. This is a conservative assumption
made in the absence of any data categorizing actual use
practices. Fogging is not always carried out in conjunction
with spot fumigation, and aeration (opening) is sometimes
performed several hours to a day prior to start up.
6/ Assuming a 70 kg worker.
-55-
-------
Table 19. Inhalation exposure of mill workpra
Ayarage concentration
1
01
en
Duration of EOB in breathing zona
Job Category activity {firs)!/ (wj/p3j2/
Hill worker 3.8 (based on level
of detection in air)
Hunter of
applications
per year='
12-14
I/ During first working day after fumigation.
2/ IDEA, 1978. Estimate based on level of detection in the IHE, 1978 study.
3/ DPRA, 1978.
4/ Assuming 1001 retention of ED6 and a respiratory rate for moderate activity of
•q/yr
inhalation
exposure
656.6-766.
1.8 »3/hr
•g/kg/yr
inhalation
exposure
1 9.4-10.9
(Spector, 1956).
5/ Assuming a 70 kg worker.
-------
187
Table 20. Peculations at Risk
Site
Soil injection -
Florida citrus fumigation
Texas citrus fumigation
Hawaii fruit fumigation
Grain storage
3/
Spot treatment —'
Baric treatment
Termite treatment
Japanese Beetle control
Parasitic nematode control
4/
Bee-hive supers-!-'
Vault fumigation
a) about 25 commercial applicators
b) up to 13,200 farmer applicators
a) 22 State employees
b) 9 Federal employees
cj 12-30 laborers per warehouse
d) unknown number of truckers
e) 3 fumigation stations
a) 30 APHIS personnel
by 75 commercial personnel
c) unknown number of truckers
d} 25 fumigation stations
a). 13 APHIS employees
b) 10 State personnel
c; unknown number of commercial
personnel
d) IS fumigation stations
a) 200 commercial applicators
b) potentially 50,000 - 60,000
farmers
-------
188
Table 21 Summary table of inhalation exposure to EPS
1. Soil injection Average dose in mg/kg/yr
Private Farmer/Applicator 1. 0.01 - 1.8-1-'
2. Citrus Fumigation (Florida)
a. Fumigation station: 2. a. 2.3-7.5
Corridor operators
b. Fumigation station: b. 5«1 - 6.5
Outdoor operators
c. Truckers/Station c. 0.4-2.1
personnel
?/
d. Warehouse: d. 287—'
Indoor laborers
e. Warehouse: e. 75-3
Outdoor laborers
f. Warehouse: f. 151.8
"Stickmen"
3.
4.
5«
6.
7.
8.
9.
10.
Spot Treatment
a. applicator
b. mill worker
Grain Storage Treatment
Bark Treatment
Bee-Hive Supers
Termite Treatment
Vault Fumigation
Japanese Beetle Control
Parasitic Nematode Control
3-
4.
5-
6.
7.
a.
9.
10.
a.
b.
No
No
No
No
No
No
No
4.3-59
9-4-10
Data
Data
Data
Data
Data
Data
Data
.3
.9
1_/ This excludes pineapple use, for which the nrivate
applicator/loader dose may be as high as 7.6 mg/kg/yr.
Specialized cultural practices may lower this dose significantly.
2_/ Based on a single personal sample of 8.99 mg/nr . Area
samples, however, support the presence of such high concentrations
(Mittelman, 1980).
-58-
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189
techniques for assessing the magnitude of cancer risk to humans based on animal
data are at best very crude. This is due to several causes, e.g., un-
certainties in the extrapolation of dose-response data to very low dose levels
and differences in levels of susceptibility in animals and hunans.
Accordingly, these risk estimates are neither scientific certainties nor
absolute upper limits on the risk of cancer from exposure to EOB. The
estimates should therefore be viewed as an index of potential health hazard
that incorporates both the degree of carcinogenicity of the compound in animals
and the measured, and/or estimated hunan exposures.
The CAG has estimated an individual's lifetime probability of SDB-induced
cancers resulting from:
. ingestion of EDB in treated food commodities (CAG, 1980a)
. occupational inhalation exposure to SDB (CAG, 1980c)
Risk estimates for EDB dietary and occupational exposure were calculated using
a standard one-hit no-threshold model based on the following general equations;
—3x
Risk * 1-e ; and
B = (1/y) In [1/(1-P)I ;
where: 3 » slope coefficient of the one-hit model
P =« (Pt-PcJ/d-PO
Pc= incidence of tunors in control animals
Pt*3 incidence of tunors in test animals
y • test animal exposure (ppm)
x » potential human exposure (ppm)
As will be discussed below, the Agency adjusted the slope coefficient (3)
of this equation to account for differences between exposure routes of the
laboratory study used, which was gavage, and the estimates of amounts of EOB
inhaled and consumed via dietary contamination.
a. Dietary Exposure
The CAG estimated cancer jisks associated with EDB residues in the diet
using the Agency's dietary exposure analysis (Holder, 1930), and the results of
a long-term bioassay study of Osborne Mendel rats and B6C2T1 mice, completed by
the National Cancer Institute (Hazelton Laboratories, 1975). EDB was
administered by intubation for two years, causing a significant increase in the
incidence of gastric tumors. The Agency used this study to derive a risk
equation for lifetime exposure, measured in rag/kg/day. This equation
incorporated both time and dosage in estimating tunor response rate.
The Agency recognised that use of the NCI study could be criticized
because the dose delivered by gavage might not be comparable to dosing by
ingestion or inhalation. As a result, the Agency adj usted the NCI tunor
incidence results to account for the potential differences in tumor incidence
which may occur because of differences in exposure routes. Through a
comparison of the adj usted NCI figures with the results of a dietary DHCP study
administered to CH albino rats (Hazelton Laboratories, 1977), the CAG derived
an approximate estimate of the relative carcinogenic effectiveness of the two
methods of administration and adjusted for EDB potency via the dietary route.
To obtain an estimate of EDB potency via dietary ingestion, the intubation
value for EDB (3 * 31.73) was multiplied by the ratio of dietary to intubation
-59-
-------
190
parameters found for DBCP, which gave: 3 » 31.73 x 0.5897 » 18.71. This
adj ustaient is based on the assumption that the ratio of oral to intubation
tumor incidence is the same for EDB as for DBCP because the t*^o pesticides are
similar in both their chemical structure and their carcinogenic potential (CAG,
1979).
Estimates of cancer risks associated with SDB residues in the diet are
illustrated in Table 22 which is based on "probable SDB dietary burden." The
estimated lifetime probability_gf EDB-induced cancer is 2.6 x 10 for grain
fumigation of wheat, 5.60 x 10 for soil fumigation, 2.7 x 10 for
quarantine fumigation of tropical fruit, 5.1 x 10 for spot fumigation of
wheat, and 1.8 x 10 for quarantine fumigation of citrus fruit. The total
lifetime probability of EDB-induced cancer is 3.2 x 10
Table 23, based on "realistic worst case EDB dietary burden," shows the
lifetime probability of EDB-induced cancer_from general use categories. The
probabilities range from a low of 6.6 x 10 for soil fumigation and
quarantine fumigation of tropical fruit to a high of 5.7 x 10 for
quarantine fumigation of citrus fruit. Other probability values are
1.2 x 10 for spot fumigation of wheat and 5.3 x 10 for grain fumigation
of wheat. In summary, Table 23 shows that the average lifetime_probability of
EDB-induced cancer from residues in an average diet is 1.5 x 10
Table 24 lists the risks of EDB-induced cancer from ingestion of crops
grown_in soil fumigated with EDB. The range extends from 0 probability co 8.3
x 10 for melons. The total risk is 4.2 x 10 . This risk assumes that
crops bear residues up to 0.001 ppm.
b. Non-Dietary Exposure
Risk estimates for those groups occupationally exposed to SDB are based on
the Agency's "Non-Dietary Exposure Analysis for EDB Uses" (Mittelman, 1980),
and the results of a recent study designed to assess the carcinogenicity of
inhaled EDB to Sprague-Oawley rats. The Agency (CAG, 1980c) derived a direct
estimate of the carcinogenic potency of inhaled EDB using a statistical model,
adjusted for the lack of full lifetime exposures, and applied it to the results
of this study. The Agecny used the significant tumor types found in the female
rat to estimate the lifetime probability of a canper case in humans. This
lifetime probability was estimated to be:
. -1.7X
P » 1-e
where:
X » estimated human lifetime average exposure
The CAG applied the above statistical model to the Agency's estimates of
occupational inhalation exposure and numbers of people exposed. Table 25
presents the risks resulting from occupational exposures to EDB vapors. The
exposure level presented in the second column of the table was obtained by the
calculation d » (40X)/(71.3 x 365), where X is the exposure level in terms of
ng/kg/year. It Is assumed that of a theoretical 71.3 year lifespan, 40 years
are spent in the occupation. Although the estimates of the lifetime
probability of cancer presented in the table are in the high range, of
particular concern are the risks to citrus warehouse workers whose estimated
lifetime risks of EDB induced cancer can be as high as 4 chances in 10 of (CAG,
19SOc).
-60-
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191
The Agency (Mittelman, 1980) has estimated that from 50,000 to 50,000
workers in grain storage facilities are exposed to EDB. The risk to these
workers cannot be estimated because the level of exposure is not known. Risk
estimates for the lower volune uses of SDB were not calculated, because of a
lack of exposure estimates.
2. Mutagenicity
As discussed earlier in this chapter, the presumption of mutagenic risk to
humans from exposure to EDB has not been rebutted. The Agency concludes the
human exposure to EDB also result In risk of mutagenic damage.
The Agency is also developing Mutagenicity Risk Assessment
Guidelines that will be utilized by the Agency for various
chemicals as needed.
3. Reproductive Effects
As discussed earlier in this chapter, the presumption of r sk of
reproductive effects to humans from exposure to SDB has not been rebutted. No
quantitative reproductive risk estimates will be developed, because the
available health studies were determined to be inadequate to support a
quantitative assessment.
4. Summary and Conclusions
The Agency has applied results from laboratory studies in estimating the
individual lifetime probability of EDB-induced cancers from both dietary and
occupational exposures. The dietary risk estimates from all registered uses
range from 3.2 x 10 for the "probable dietary burden", to 1.5 x 10 for
the "realistic worst case dietary burden", with quarantine fumigation
contributing 2.1 x 10 and 8.4 x 10 to the respective ranges. The
occupational risks of SDB-induced cancers resulting from inhalation of SDB
vapor range from 1.8 x 10 to as high as 4 chances in 10 for citrus
warehouse laborers.
Although the Agency concludes that there is a risk that mutagenic damage
and reproductive disorders could result from exposures to SDB, the Agency has
not quantified these risks.
D. Risks of the Alternative Pesticides to EDB
Table 26 summarizes all of the known risks for major alternative chemicals
to EDB. These seventeen pesticides could be substituted for EDB depending upon
ths use that was cancelled. The regulatory status for each is also given.
Four of the substitute chemicals are either on the RPAR list or candidates for
RPAR, and most are restricted to use by certified applicators. In Chapter V,
the risks of each substitute are compared to EDB on a use-by-use basis.
-61-
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192
TABLE 22
CANCER RISK DDE TO "PROBABLE EDB
DIETARY
Source EDB dietary
burden
(lag/kg/day)
lifetime probability
of EDB-induced
cancer
Soil 2.6 x 10 '
Fumigation
Grain 7
Fumigation 1.8 x 10~A
(wheat) (4.1 x 10"5)
Spot /.
Fumigation 3.2 x 10
(wheat)
Quarantine
Fumigation: -
Citrus 1.1 x 10~5
Tropical ,-
fruit 1.7 x 10~°
5.6 x 10 ^
2.6 x 10",
(6.28 x 10"4)
5.1 x 10"
1.3 x 10"
2.7 x 10"
Total
1.6 x 10-|
(5.7 x 10~5)
3.2 x 10"
(9.0 x 10"4)
The parenthesized value (4.1 x 10""' mg/kg/day)
is calculated from 57 samples of residue. Non-parenthetical
values were derived from models using application rates.
(Litton Bionetics, Inc., 1978).
-62-
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193
TABLE 23
ESTIMATES OP CAHCER RISK DDE TO "REALISTIC WDRST CASE
EDB DrSTART BURDEN™
Source
EDB dietary
burden
(mg/kg/day)
Lifetime probability
of EDB-induced
cancer
Soil
Fumigation
Grain
Fumigation
(wheat)
Spot
Fumigation
(wheat)
Quarantine
Fumigation:
Citrus
Tropical
fruit
Total
4.1 x 10"°
3.3 x 10-5
7.6 x 10"6
3.5 x 1
-------
TABLE 24
UPPER BOUND CANCER RISKS DUE TO INGESTION OP CROPS GROWN IN SOIL FUMIGATED WITH EDB
Crop
Maximum expected
residue ppb
Estimated dietary burden
at current use level in
mg/kg/day
2.6 x 10
~7
Lifetime probability
of EDB-induced cancer
Asparagus
Broccoli
Carrots
Cauliflower
Corn, sweet
9
Cotton
Cucumbers
Eggplant
Lettuce
Lima Beans
Melons
Okra
Parsnips
Peanuts
Peppers
Pineapples
Potatoes
Squash
Strawberries
Sweet Potatoes
Tomatoes
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0 q
2.4 x 10j?
2.5 x 10~7_
5.6 x 10"10
0 .
7.5 x 10"
5.0 x 107
1.1 xicrg
6.6 x 10_1U
2.1 x 10J:
5.5 x 10~?
1.2 x 10~b
0 -11
9.0 x 10 n
0 _R
2.0 x 10J?
1 .5 x 10~°
0 q
2.0 x 10 ^
5.4 x 10j(
4-9 x 10"°
0 *
3.8 x 10"S
4.0 x 10 '
9.0 x 10 y
0 q
1.2 x 10"^
8.0 x 10"'
1.7 x 10_|
1.1 x 10 „
3.4 x 10"'
8.8 x 10"'
2.0 x 10"'
0 q
1.4 x 10 y
° -7
3.3 x 10 '
2.4 x 10"'
0 -3
3.2 x 10"?
8.7 x 10"°
7.8 x 10"'
<£>
4.2 x
-------
in
Table 25
CANCER RISK DUB TO OCCUPATIONAL INHALATION OP EDB
Exposed group
Soil injection
farmer applicator
Fruit fumigation^ '
station corridor
operator
station outdoor
operator
trucker/station
personnel
Warehouse^'
Indoor laborer
Outdoor laborer
Stickman
Spot fumigation
Applicator
Millworker
Range of exposure
(mg/kg/day)
1.5 x
3.5 x
7.8 x
6.2 x
6.6 x
1.5 x
10 5 - 2.8 x
10~3 - 1 .2 x
10~3 - 10.0 x
10"4 - 3.2 x
0.4
0.1
0.2
10~3 - 9.1 x
10 * - 1.7 x
10 3
io-2
io-3
10~3
,o-|
10-^
Lifetime
estimates
1 .8 x 10~5
4.1 x 10~3
9.1 x 10~3
7.2 x 10~4
7.7 x 10~3
1.7 x 10
probability
-3.
- 1.
- 1
- 3.
0.
0.
0.
- 0.
- 2.
2 x
3 x
.2 x
8 x
4
1
2
10
0 x
io-3
io-2
io-2
10~3
10"2
No. of workers
exposed
13,200
n(l)
10
10
4-10<2>
4-10
4-10
2400 -
16,000
- 6000
hi Assumed that 31 federal and state employees are evenly distributed.
(2) Per warehouse. Seasonal variation. Assumed that 12-30 laborers per warehouse are evenly
distributed.(Mittelman, 1980)
(3) Figures are for Florida only. No data are available as to exposures in Texas or Hawaii.
en
-------
196
Table 26 Human Hazards of Substitutes for E2B
(* - most liVcely alternative it all EDB uses vere cancelled)
Chemical
Aldiearb
*Aluminiua
Phosphide
Carbofuran
*Carboa Disulfide
*Carbon Tetrachloride
Chloropicrin
Dasanit
Potential Hazards to Man
Acutely Toxic
Acutely Toxic
Explosive
Anticdolinestarase
Reproductive Effects
Acutely Toxic
lamuno-tuppressant
Explosive
(To* Profile
was not done-
literature being
assembled)
Oncogenicity
Mutagenieity
Hephrotoxicity
Hepatotoxicity
Lung Irritant
Skin Irritant
Acute Toxicity
Ancicholinescerase
Regulatory Status
Some uses restricted
Others under evaluation
All uses are
restricted
Most uses restricted
Others under
evaluation
Most uses
restricted
Notice of 3.PAH. issued
10/15/80.
Most uses
restricted
No action
D-D
(contains
1,3 dichloropropene)
*Ethylene Dichloride
Hydrogen cyanide
Oncogenicity Lang, liver
& kidney damage
Mutageniciry
Eye & skin
irritant
Oncogenicity
Mutagenicity
Acutely Toxic
See Telone
Accepted
for pre-a?Aa
All uses restricted
-66-
-------
Ch**" •*'"'*;
*Methyi Broaide
Mocap
Hemacur
197
Hazards of ZDB Substitute
Potential Hazards to
Paradichioro benzene
Silica, aercgel
Verier (contains
1,3 dicfaloro-
propene
CSS lesions
fl»rfn irritant
Jiitagenicity
Anticnoiinesterase
Acuta
Chanicals - (cont'd)
Man Reguiatory Status
4 sJcLn irritant
Onccgenicity
Irritant
Telone Onccgenicitj J!
(1,3 dichloropropene) (in vitro)
3kL" irritant
references: Federal Register, 1978
Federal Register, 1979a
Federal Register, 1979b
Mishra, L; I978b
Most uses restricted
Accepted for Pre-5PAH
review
Seme uses.restricted
Others under evaluation
Liquid formulations are
restricted
Granular formulations
are proposed for
restriction
Accepted for
pre-SFAR
Ho Action
Accented for STAR
See Telone
-67-
-------
198
III. BENEFITS SUMMARY FOR ETHYLESE DIBROMIDE
A. Introduction
EDS is used for a variety of agriculturally related activities- It is
produced in the U.S. by the Great Lakes Chemical Corporation and Dow Chemical
Company, and its production and marketing data are confidential. However, it
has been estimated that in recent years approximately 13 to 15 million pounds
of EDB have been used annually as a pesticide active ingredient. Sites treated
include: preplant soil fumigation of agricultural crops (tobacco, pineapple,
citrus, peaches, peanuts, cotton and various vegetables); fumigation of stored
beehive supers; termite control; fumigation of stored grain; spot ftxnigation of
flour milling machinery; for Federal (APHIS) quarantine programs; and on felled
logs for control of bark beetles.
Estimates of annual usage were made in 1973 by the USDA/State and EPA
Cooperative Assessment Team. In 1979, DHCP, one of the major alternatives to
EDB, was largely banned from the market. This most likely resulted in some
increase in EDB usage for certain sites. Because it. was not possible to
determine the magnitude of these increases, the original 1978 estimates of
annual usage were used as a base for most of the sites analyzed.
Benefits analyses for all sites except stored grain and flour mills were
prepared jointly by economists of EPA and USDA (Abbreviated Benefits Analysis
of Pesticidal Uses of Ethylene Dibromide, January, 1979). Analyses of flour
mills and stored grain were performed under EPA contract by Development
Planning and Research Associates, Inc., of Manhattan, Kansas.
The alternatives to EDB were chosen on the basis of cost, efficacy/ and
availability. Economic impacts of alternatives were estimated using partial
budgeting. This methodology allowed measurement of the change in control costs
and yield, if any, while holding all -other inputs and their costs constant.
Cancellation of all current uses of SDB are expected to result in annual
losses to users of approximately $60.0 million (Table 27). This represents
losses due to both increased cost of treatment and decreased value of
production for certain crops. The largest single impact would be noticed
through the APHIS citrus quarantine program, where shippers and producers could
suffer a net loss of S24 million, and where balance of payments deficits could
increase by approximately $18 million, if the export market to Japan were lost.
In calculating these impacts, it was assumed that only currently registersd
pest control methods would be available at the time EDB cancellation becomes
effective. Over 30% of the estimated impact of $60 million would occur in the
AP^HIS quarantine program for which there are no known chemical alternatives to
EDB. Extensive research conducted in recent years demonstrates that the use of
gamma radiation can be an effective pest control method (Interdepartmental
Committee on Radiation Preservation of Food, December 1978). A nunber of
foreign countries and the U.S.A. have approved irradiation of certain food
products for human consumption (Appendix II). Though irradiation of wheat,
wheat flour and white potatoes has been approved in the U.S., the Food and Drug
Administration, the Federal body responsible for these approvals, has .not yet
resolved a 1973 petition (FAP *2045) from USDA requesting approval of the use
of gamma irradiation on papayas and citrus. Should this pest control method be
approved and accepted by foreign export markets, the impacts of cancelling EDB
may be reduced significantly.
-68-
-------
EDB is used in combination with ethylene dichlorida and carbon
tetrachloride for insect control in stored grain. A total estimated 630,000
pounds of EDB active ingredient are used annually in grain storage facilities:
409,000 pounds are applied on farms, while 221,000 pounds are used in
commercially stored grain. Approximately 225 million bushels of stored grain,
or about 2% of the grain produced in the country, are treated annually with
funigants containing EDB.
The most likely alternative to SDB-containing mixtures is the 80%/20%
mixture of carbon tetrachloride and carbon disulfide at on-farm storage
facilities, and aluminum phosphide at off-farm storage centers. Because on-
farm and off-farm facilities vary greatly in air-tighcness the substitutes also
vary; the tighter the facility, the more likely it is that the substitute would
be aluminum phosphide. When used as directed, both carbon tetrachloride/carbon
disulfide and aluminum phosphide will be less costly than SD3. As a result,
fumigation costs will actually decline if SDB becomes unavailable and is
replaced with these alternatives. The Agency estimates a $500,000 to
$-2,260,000 annual savings from use of these EDB alternatives.
Another alternative treatment method which is effective against a broad
spectrum of pests of stored grain is the use of a controlled atmosphere of
carbon dioxide, nitrogen and combustion products of natural gas. These gases
can be circulated through a sealed bin, reducing the oxygen in the bin
atmosphere to a very low level and killing any pests. In all cases, bins must
be sealed tightly, grain temperatures must exceed 70 F. and the exposure
time must be at least four days. The commodities are not contaminated with any
chemical residues. The performance of this treatment method is optimum in
silos and other readily sealed sites, but use in flat bed storage is unlikely.
In response to. a petition for exemption from tolerance submitted by the USDA IR-
4 minor use program, the Agency has proposed to grant this exemption (Federal
Register, Vol. 45, No. 136, July 14, 1980, p. 47168). Commerical acceptance
and use of this controlled atmosphere method could occur once the exemption
from tolerance is made permanent; thus, another alternative for this use of EDB
could become available. The Agency has no information regarding the costs of
such a treatment system and would be interested in obtaining such information
from any knowledgeable party.
C. Quarantine Fumigation of Citrus, Tropical Fruits and Misc. Fruits and
Vegetables.
USDA's Animal and Plant Health Inspection Service (APHIS) requires the use
of SDB in its quarantine program to destroy certain fruit flies before they
become established in parts of the U.S. For the same reason, Japan also
requires that all fresh grapefruit imported from the U.S. be treated with SDB.
The target flies include the Mediterranean, Caribbean, West Indian, Oriental,
Melon, Queensland, and the Cherry fruit fly. In 1977, approximately 33,500
pounds active ingredient of EDB were used to meet the requirements of APHIS and
Japan.
There are currently no registered chemical alternatives to SDB for
quarantine purposes. Vapor heat (112 F for 4-6 hours, followed by chilling)
and cold storage (36 F for 10-22 days) can control these flies as affectively
as EDB, however, its use often results in varying and considerable degrees of
fr ui t damage.
-69-
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Table 21. Annual Economic Impacta of Cancel ling Ethylene Olbromlde
Ifeiu sites
Extent of use
Active ingredient {Units Treated)
Change In Cost
of Treatment
Applied Thousand pounds
Tobacco
Pineapples
Citrus
A. Preplant
B. Burrowing nouatode
containment
Peaclies 2/
Forestry 3/
1 Termites
Q Grain Storage
1 Flour Hilling
Quarantine (AlllIS)
Peanuts
Cotton
Vegetables
Money cowlis
Total
2,10(1.0
572.4
20.0
252.0
170.0
20.0
20.0
630.0
465.0
83.5
4,197.4
721.8
5,600.0
20.0
14,872.1
77,600 acres
11,500 acres
100 acre
500 acres
2,000 acres
68,000 acres
12,400 structures
125.7 to 392. 0 mil. bu.
391 mill
494.5 mil. Ibs.
257,390 acres
55,600 acres
180,000 acres
5,679,000 supers
~
1,200.0
281.5
3.5
44.0
20.3 to 118.2
7.4 to -15.8
mknoun
-2,258.0 to -500.0
4,000.0 to 7,700.0
538.9
2,500.0
435.7
3,800.0
3,686.2
14,895.0 to 19,776.2
Decrease in
Value of
Production
Balance
Market/ of
User Consumer Payment
Impacts Impacts Im[>acla
thousand dollars. I/
0
1,218.5
0
0
0
unquantlfiable
-
0
0
24,1. 4.0
11,000.0
0
0
6,500.0
42,882.5
1,200.0
1,500.0
3.5
44.0
20.3 to 118.2
7.4 to 15.8
-
2,258.8 to -500.0
4,600.0 to 7,700.0
. ,
24,702.9 '
13,500.0
435.7
3,800.0
10,186.2
57,775.5 to 62,658.7
none
minor
none
none
none
none
none
none
$0.016 to $.028
per capita
0
0
0
0
0
0
0
0
0
price 18,384.0
reduction
for grape-
fruit) price
Increase for
papayas fc waivgoes
none
none
none
minor/none
18,384.
0
0
0
0
0
2V Assumes registration of DOCP. if DBCP Is permanently cancelled, economic Impacts would range from approximately
~ $379,000 to $610,00 annually.
3/ Including residential use.
Primarily borne by the growers rather than the actual users. (ATIUS program of ECU).
to
o
o
-------
201
An additional method, gamma irradiation, shows promise as a substitute for
EDB post-harvest fumigation. However, as discussed above, the Food and Drug
Administration has not reached a decision on approval of the use of irradiation
on fruits and vegetables.
Loss of EDB may result in economic impacts to fruit and vegetable shippers,
producers, and consuaers. Shipper impacts would result from an approximate 700
percent increase in treatment costs, from 30.87 per 1,000 pounds of commodity
using EDB to S6.2S per 1,000 pounds of commodity using either vapor heat or
cold storage treatments. Changes in imports and exports of grapefruit,
tropical fruits and miscellaneous vegetables would result in anestinated
balance of trade deficit of $13 million annually, assuming Japan would not
accept non-SDB treated grapefruit. However, if Japan agrees to accept
grapefruit treated with alternative methods, this balance of trade deficit
would be eliminated. These impacts are summarized by commodity as follows:
1. Grapefruit
Under current trade agreements, a cancellation of EDB could result in a
loss of exports to Japan due to Japanese regulations which require EDB
treatment. A loss of exports would result in decreased treatment costs of
$263,300, while shipments of grapefruit by other shippers (imports and
interstate) would result in increased treatment costs of $265,000 (vapor heat
or cold storage), resulting in a net increase in treatment costs of $1,700.
Under current trade agreements, the domestic market would have to absorb the
grapefruit previously shipped to Japan (about 20 percent of domestic fresh
consumption) which would result in price reductions and an estimated decrease
in the annual value of production of over $29 million and a balance of payments
loss of over $27 million. IS Japan agrees to import grapefruit treated by
alternative methods (vapor heat, cold storage, or gamma irradiation), the
economic impacts of cancellation would be significantly reduced. Specifically,
treatment costs of fruit exported to Japan would increase $1.5 million annually
with the use of vapor heat or cold storage (changes in treatment costs with
the use of irradiation have not been evaluated). Also, there would be no loss
in the U.S. value of production (due to excess supplies) and the $27 million
balance of payments loss would not occur.
2. Papaya
Cancellation of EDB could result in a loss of exports to Japan due to
Japanese regulations requiring EDB treatment for papayas. A loss of exports
would result in reduced treatment costs of $2,700 and a loss in revenue of $1.2
million. Interstate shipment would result in increased treatment costs of
$73,500 for a net increase in treatment cost of $70,800. The alternative
treatment methods of heat or cold would result in a high level of fruit
damage. Although papayas would no longer be exported to Japan, the amount of
fruit damaged would exceed the previous level of exports. Therefore, domestic
supplies would decrease and prices of papaya would increase.
Cancellation of EDB would result in a loss of imports of mangoes. This
loss would result in decreased annual treatment costs of $10,900. The domestic
producers would not have competition from imports, resulting in short tern
price increases and an increase in the value of domestic (untreated) product
estimated at $2,104,000 per year.
-71-
-------
202
4. Other Citrus
Cancellation of EDB would result in increased treatment costs of $473,400
per year due to use of alternative treatments. The alternative treatments
would result in product damage with a decrease of $2,003,000 in product value.
5. Miscellaneous Fruits and Vegetables
A cancellation of EDB would result in increased treatment costs of $7,600
due to use of alternative treatments. The alternative treatments would result
in decreased value of product of $31,000 per year because of product damage
from use of alternatives.
6. Summary of Quarantine Fumigation Impacts
The overall impact of EDB cancellation on the APHIS Quarantine Program
would amount to an estimated increased annual treatment costs of 3538,900 and
an estimated decrease in the value of production of $24,800,800 per year. In
the short term, consumers would have price decreases for grapefruit and price
increases for papayas and mangoes. The magnitude of these increases was not
estimated due to a lack of data. In the longer terra, production adjustments
would result in price changes that would partly offset the short term impacts.
Under current trade agreements, the cancellation of EDB usage in the APHIS
quarantine programs would have an adverse impact on the U.S. balance of
payments. This total impact, roughly estimated at $18.4 million, would
eventually be borne by the consvmer. The major factor would be the $27.4
million loss in the export market of grapefruit to Japan. In addition, export
market of papayas to Japan, valued at $1.2 million, would be lost. Mangoes,
valued at $8.2 million, would no longer be imported. Other imported
commodities previously treated with EDB would be damaged, resulting in a $2.0
million positive impact on the balance of payment position.
D. Spot Fumigation of Grain Milling Machinery
EDB has been used for ever 20 years as a spot fmigant for control of
insect populations which invade flour milling equipment. Currently, an
estimated 465,000 pounds of EDB active ingredient are used annually for this
use. A 70 percent EDB and 30 percent methyl bromide combination is common,
although other EDB formulations are also used. The only alternative spot
fumigant that does not contain EDB is a mixture of 75 percent ethylene
dichloride and 25 percent carbon tetrachloride. However, the dosage required
for this pesticide is so large that the milling industry does not consider this
mixture to b« a viable substitute. It must be used more frequently (two to
four times that of EDB fumigants) to exert any reasonable degree of control.
The^larga amount of liquid material applied nay cause the system to clog,
requiring extra preparation time before milling can be resumed. The overall
results of using this alternative mixture include the actual application of a
much greater quantity of chemicals, a higher cost for fumigant, the use of more
Labor, and more down time of the mill. Carbon tetrachloride is also an RPAR
candidate. If that compound were cancelled, then no spot fumigant would
remain.
-72-
-------
203
The only viable alternative to spot fumigation is general funigation of the
entire mill spacs. Methyl bromide and aluminum phosphide are currently the two
most commonly used general space fumigants, accounting for approximately 75 and
25 percent, respectively, of the general space fumigant market.
The principal economic impact resulting from the cancellation of EDB as a
spot fumigant in flour milling equipment would result from the increased cost
of substituting general fumigation of the entire mill space (with methyl
bromide or aluminum phosphide) for the current practice of spot fumigation of
individual items of milling equipment.
It is proj ected that an average of four general fumigations per year would
be required to achieve satisfactory control. The current practice is 12-14
spot fumigations and one general fumigation annually. Thus, the change would
require that mills undertake three additional general fumigations per year but
save 12-14 spot fumigations.
Based on the relative cost of the present versus the projected systems, the
most likely increase in annual costs would be a total of 33,800,000 in the
wheat, dur-un, and rye milling industries and $800,000 in the dry corn milling
industry, respectively. These impacts would result in direct costs of 514,000
per year in wheat and rye mills and 58,600 in dry corn mills. Based on total
human consumption of wheat, durum and rye flour, and dry corn mill products,
the consumer impacts would be small, approximately 1.6 cents per person.
If five rather than four general fumigations are necessary per year, wheat
nd rye mill costs would increase $6.4 million annually, and com mill costs
would increase S1.3 million annually, resulting in increased costs of
approximately $21,500 and $14,000 per mill, respectively. Based on total human
consumption of wheat, durum, and rye flour and dry cornmill products, the
consumer impact under the more conservative estimates would continue to be
small—approximately 2.3 cents per person per year.
2. Preplant Soil Fumigation
1. Tobacco
SDB is used to control root-knot, root lesion, and stunt nematodes on flue-
cured tobacco in Florida, Georgia, North Carolina, South Carolina and
Virginia. Approximately 2.1 million pounds of EDB as an active ingredient were
used in 1977, two-thirds of this in North Carolina.
Alternative registered chemicals to EDB include other fumigants (DD and
Telone II), multi-purpose fumigants (Telone C-17, DD/Pic, Vorlex), and non-
fum\igants (ethoprop, fensulfothion, carbofuran and oxamyl). Even without use
of SDB, nematodes could be eliminated, through an integrated pest management
program involving rotation, setting healthy transplants, and early root and
stalk destruction. Growers switching from EDB to other fumigants or from multi-
purpose formulations containing EDB to other multi-purposs fumigants vrould not
experience any significant change in yield regardless of nematode population
levels, but the alternatives to EDB are more expensive.
If EDS were to become unavailable, tobacco growers would spend
approximately SI.2 million more for control than they currently spend using
EDB. These increased control costs represent an increase in total production
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costs of approximately 1.2 percent. Long run economic impacts to tobacco
growers would be slight. Likewise, little if any impact -would be noted at the
market or consumer level if this registration of EDB were cancelled.
2. Pineapple
All commercial U.S. pineapple production is located in Hawaii, and all
Hawaiian pineapple acreage must be treated with nematocides. Damage is caused
either by the root-knot nematode or the reniform nematode. Approximately
572,400 pounds of EDB are used annually for nematode control on Hawaiian
pineapple fields. The alternative to EDB is OBO? applied either in combination
with 00 or Telone. Depending on soil conditions and species of nematode
present, each of these nematocides has its unique place in nematode control
programs. EDB is used on approximately 11,500 acres subject to high soil
moisture.
Since pineapple is a perennial crop (with a normal rotation of 4 years),
only one-fourth (2,875) of the above mentioned 11,500 acres needs treatment
annually. Substitution of a combination of DBC? and DO for EDB on this acreage
would result in yield losses of approximately 4.8 percent, as well as increased
control costs of about $98 per acre- 1979 price increases in DBCP relative r.o
other nematocides could further increase these costs by $75 per acre since DBCP
prices have increased from $9.35 to $20.00 per gallon. The present net value
of the combination of these economic impacts, (estimated at 1977 dollars and
prices) over the entire production cycle following removal of EDB (a 5 1/2 year
period), is estimated at $5.2 million (using a 7 per cent discount rate). In
the long run, approximately $1.5 million additional cost per year would be paid
by Hawaiian pineapple growers until a satisfactory substitute for EDB is
registered for use. Minor market or consumer impacts are expected.
3. Citrus
SDB is registered for preplant use in fruit tree planting sites, including
citrus groves. Target pests are the citrus nematode and the burrowing
nematode. SDB use in citrus (preplant) has been estimated at 20,000 pounds
active ingredient annually. This quantity would treat approximately 110 acres,
or less than one percent of new citrus acreage planted annually. The most
viable alternatives to EDB for preplant citrus use are DD and Telone.
A second use of SDB in citrus is barrier establishment and maintenance to
control the burrowing nematode in Florida conducted under a cooperative Federal-
State Program. In this program, about 250,000 pounds active ingredient
annually are chisel-injected in barrier zones ranging in width from 16 to 32
feet.
^ Economic impacts associated with cancellation of EDB for preplant use on
citrus are expected to be minimal. In these preplant situations, use of
alternatives will increase direct treatment costs by an amount ranging from
$17.50 to $45.50 per acre depending on the alternative neraatocide selected.
However, because of the low volume use of EDB for this use site, total cost
increases to affected growers will be only $3,500 per year. In the burrowing
nematode control program, use of alternatives will increase program costs from
$25,000 to $53,000 per year/ depending on the alternative chemical chosen.
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No short-tern market or consumer effects are anticipated as a result of
this EDS restriction. The long-run situation is Lass certain, especially if
alternatives prove less effective for government-sponsored nematode containment
programs. The extent of long-term impacts cannot be precisely determined, but
should not be severe.
4. Peaches
EDB is used as a preplant nematocide on peaches. Primary target nematodes
are ring, root-knot, lesion, and dagger nematodes. Prior to the suspension of
DBCP, approximately 170,000 pounds of ECS active ingredient were used annually,
enough material to treat about 2,000 acres of peaches. Almost all of this
usage has been in the East, where over 13,000 acres of peaches are planted
annually. Prior to the 1979 suspension, DBCP was used to treat an additional
8,325 acres annually. IS the suspension of DBCP becomes a permanent
cancellation, EDB would be the preferred chemical on these acres.
Registered alternatives to EDB for use in peach orchards are nunerous, and
include DBC? (tamperarily suspended), DO, Telone, Vorlex, methyl bromide,
zinophos, and chloropicrin. The major alternatives (DBCP, DO, and Telone) are
equal in efficacy to SDB.
If DBCP use is allowed to continue on peaches, increased grower costs on
the 2,000 acres currently treated with EDB *ould range between $20,300 and
3118,180 annually ($10-559 per acre), depending on the alternative chemical of
choice (CBCP, DD, or Telone). However, if DBCP is permanently cancelled and
EDB is assumed to be the preferred chemical on 10,325 acres, grower costs of an
EDB cancellation would range from $373,700 to 3610,100 annually (approximately
537 to 559 per acre) depending on the alternative chemical of choice (DD or
Telone). At the industry level, the increased costs are not significant under
either scenerio (with and without DBC?). No significant market or consumer
impacts are expected if EDB becomes unavailable to peach growers.
5. Peanuts
About 17 percent of peanut acreage in the major U.S. peanut-producing
regions is currently treated with SDB, resulting in annual EDB usage of
approximately 4.2 million pounds of the active ingredient.
There are several registered alternatives to EDB for use on peanuts,
although none are equally effective. The major liquid funigant alternatives
are Telone II and DD. Viable granular alternatives are Furadan, Oasanit,
Mocap, Nemacur, and Teraik, all of which are applied at planting. Each of
thesealtematives is more expensive than EDB. It is estimated that
substituting one of the several alternatives (choice of the particular
alternative being dependent on many biological factors) for 2D3 would result in
increased control costs to peanut growers of approximately $2.5 million per
year.
More important than increased control costs is decreased value of
production. If granular alternatives are used, yield losses of 6 percent are
estimated due to reduced efficacy. If liquid formulations are used, yield
losses will vary geographically from 7.5 to 8.0 percent. In the latter case,
yield losses because of a required 10 to 14 day planting delay required to
prevent phytotoxicity to the peanut plant. These yield losses would reduce
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producers' revenues by S11 million per year in addition to the $2.5 million per
year increase in control costs. However, government price support programs are
expected to prevent these losses from influencing consumer prices.
6. Cotton
SDB is registered for use throughout the cotton belt. An estimated 721,300
pounds were used in 1977, primarily to control the root-knot neraatode.
However/ since that time,.the suspension of DBCP may have increased usage to
1.3 million pounds annually. Telone II and 00 remain as viable alternatives,
and are equally effective under good soil conditions.
The only economic impact expected from cancellation of EOB would be an
increase in cost of control, from $13.75 per acre with EDB to about $21.00 per
acre with any of the alternatives. At an application rate of 2.5 gallons per
acre (12.1 pounds a.i per gallon), an estimated 55,560 acres are treated
annually with EDB. Use of substitutes for SDB on these acres would increase
treatment costs by $435,700 per year, donpared to the approximate $3 billion
value of the U.S. annual cotton crop, these increases are negligible.
Accordingly, no measureable market or consumer impacts are projected.
7. Vegetables
Approximately 180,000 acres of various vegetables (broccoli, carrots,
cauliflower, cucwbers, eggplant, lettuce, lima beans/ melons, okra, potatoes,
squash, strawberries, and tomatoes) are treated by preplant soil fumigation
with EOB to control nematodes. Depending on the crop in question, EDB is
applied at rates of-1.5 to 6*0 gallons per acre. An estimated 5.6 oillion
pounds a.i. EDB are used annually.
Alternatives to EDB (Vorlex, DO, and Telone II) are considered equally
effective. The loss of EDB on vegetables would result in.increased pest
control costs to vegetable producers of $3.8 million per year. There would be
no loss in vegetable production due to the cancellation of EOB. Given a
producer value of these vegetables of about $3 billion, the increased costs of
the alternative fumigants would not have a significant impact on prices of
these vegetables.
Producers of melon, lima beans, tomatoes and cucumbers would incur the
largest impacts. This is due to the number of acres of these crops treated
with EDB. Cn a per acre basis, the increased costs range from 35.38 for
carrots to $28.90 for cucumbers.
Table 28 shows costs of alternatives to EDB on vegetable crops.
No - significant market or consumer impacts are expected if EDB were not
available for use on vegetables.
?. Minor Uses
1. Fumigation o_f Felled Logs
Several bark beetle species in the West attack coni-farous trees and cause
damage which can be reduced through the use of EDB. The alternatives are
lir.dane and endosulfan. However, lindane is not considered a viable
alternative because it is in RPAR review and the lindane ?D 2/3 recoantends its
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Table 28
I
-vj
Alternative Neuatocldea Used to Replace ETUI on Selected Vegetabt
of Materials and Changes In Nomatoda Control Cost, by Crop ->
ea. Cout
With alternative ncnatocldes
Increase In neoatodu
Crop
Broccol 1
Carrots
Cauliflower
Cucumbers
Egg Plant
Lettuce
Lima Deans
Melons
(*ra . .
potatoes (white)-"
A. Mdsh.Idalio
U. Oll»r States
Potatoes (sweet)
S(|uat>li
Htrawtxtrrles
Tomatoes
Totals 2,
-' Application rates,
To am based on product
.^ » t .1
With
toe
51
381
10
201
5
5
248
330
59
990
91
214
11
15
312
923
material
labels,
D-D
as
285
6
269
11
9
462
724
129
510
152
291
6
16
524
3,479
Vorlex
$1,000
—
—
—
420
4
—
—
—
67
—
—
—
10
—
—
501
cost par gallon, and the alternative
State recommendations, efficiency of
Telone II
91
202
30
143
1
1
492
406
27
648
122
—
26
35
558
2,788
Total
176
487
36
832
16
16
954
1,130
223
1,158
274
291
42
51
1,082
6,768
Total
125
106
26
631
11
11
706
800
164
168
183
77
31
36
770
3.845
nematocldea used wora specified by the BOB
registered alternatives, and material costs
control costs
Per Acre
22.64
6.88
23.01
28.85
22.00
22.00
23.57
23.11
25.57
16.80
18.48
11.85
25.83
22.50
22.65
—
Assessment
par
acre. The a|>pllcatlon rates and material cost per gallon are aa followai
Current control prou,ra«»
Q»i 1.5 gallons par acre for Una boansj 4.5 gallons per acre for catrotaj 6 gallons par acre for swuet
potatoes and 1.67 gallons par acre for the runalnlnj vegetables (12 pounds a.1. at $5.50 per gallon).
Terr-o-Cidei B» 6 gallons par acre (8.43 pounds EOU ar»l 7.03 pounds chloroplcrln) at $16.50 per gallon.
Alternative control prograat
r>-D7 16 gallons per acre for sweet potatoes, and 11 gallons/A for remaining crops (10 pounds a.l.) at $2.80 pat gallon.
Vorlexi 6 gallons pur acre (11 poundu a.l.) at $8.00 pur gallon.
to
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cancellation for this use. Limited information indicates that endosulfan is
less effective than EDB. tonchemical controls, such as good silviculture
practices, careful site selection, avoidance of monoculture, and thinning and
removal of diseased or injured trees are also effective. However, during pest
epidemics, chemical control may also be required.
Records show that in FY 1977, approximately 20,000 pounds of the active
ingredient of EDB were used in Colorado and North Dakota only. Data for other
areas are not available. At label rates, this is sufficient material to treat
about 68,000 trees- SDB is used to treat trees that have already been
attackedby bark beetles after the damaged tree has been cut. It is applied as
an "open" log spray or under a plastic covering.
The extent to which EDB has been used for forestry purposes is not
sufficient to appreciably affect commercial timber harvests. Rather, SDB is
generally used where bark beetle damage may have aesthetic impacts to
residential areas, wildlife habitats, or recreational areas. Such impacts ara
difficult to quantify, but typical residential lots suffering tree mortality
from mountain pine beetle infestation could lose front $ 1,500-$3,000 in value.
Cost: of control could be reduced by as much as $36,000 per year if
endosulfan were to replace EDB; however, endosulfan may not be as effective as
EDB.
2. Termite Control
SDB is the only pesticide registered by SPA as a fumigant for subterranean
termite control. EDB is also state-registered in California for the control of
drywood termites. Alternatives registered for control of subterranean species
include aldrin, dieldrin, chlordane, heptachlor, pentachlorophenol (under RPAR
review), and chlorpyrifos. For drywood species, registered alternatives
include methyl bromide, sulfuryl fluoride, hydrogen cyanide, pentachlorophenol,
and silica aerogel.
Estimates of EDB use vary from 5,000 to 12,000 gallon's of formulation, or
approximately 11,500 pounds to 27,600 pounds of the active ingredient per
year. It is estimated that approximately 12,400 homes were treated with ED3
for subterranean termite control in 1977. No data were available indicating
units treated for drywood termite control.
Economic impact data regarding the use of EDB and alternative insecticides
are limited; therefore, the magnitude of user, market, and consumer impacts
cannot be precisely identified. Because Che current use of EDB is snail
relative to other insecticides, overall impacts should be minor. However,
certain homeowners, particularly in the southeastern and the southwestern U.S.,
who may experience difficulty in controlling subterranean termita infestations,
could incur substantial losses. Because of the need to apply a. fumigant into
holes drilled in concrete foundations, there are no known chemical alternatives
for homeowners in the Southeast and Southwest. The only known solution in this
case is removal of the infested wood and rebuilding.
2. Fumigation of Stored Beehive Supers and Honeycombs
Honeycombs being stored between honey producing seasons an fumigated with
EDB to control the larvae of the greater wax moth (GWM), which damage the
waxcomb and bases held mounted on frames by hive supers.
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Alternatives to EDB for this use are paradichlorofaenzene (PD3) and carbon
dioxide. In the N'orth, cold weather is a natural control. Paradichlorobenzene
is more practical to use than carbon dioxide, as the latter requires elaborate
monitoring equipment to ens-ure efficacy and safety for the user.
Paradichlorobenzene is somewhat less effective than EDB because it does not
provide control of the egg stage of the CWM.
The uss of PDB to replace EDB in the treatment of honeycombs will Increase
beekeeping costs by about $3.7 million annually. The cost per super treated
will increase about 5 cents — 4 cents with SDB versus 9 cents with PDB.
Further, with ?OB and CO there would be 7 additional treatments needed per
super.
Using the next best alternative, PDB, it is estimated that the volume of
marketable honey would be reduced 20 percent in a super previously treated with
EDB. This loss is due to decreased control of the GWM larvae which damage the
honeycomb; in turn, the damaged honeycomb must be replaced with a fresh comb
base prior to use in the hive during honey flow. Approximately one-third of
all supers in the nation would be treated for the GWM using PDB in place of
EDB. The total quantity of domestic honey would thus be reduced by 6.67
percent.
Annual honey production in the U.S. during 1975-77 averaged 191 million
pounds. Based on a 6.67 percent reduction in honey production without EDB, the
annual loss to beekeepers would be 12.7 million pounds, valued at $6.5 million.
To some extent, a production loss of this magnitude will result in higher
consumer prices, thus shifting some of the impact of EDB cancellation from the
producer to the consumer. The extent of this consumer price impact cannot be
estimated.
In addition to these economic impacts, there will probably be some losses
attributable to the reduced pollination service which bees provide. It is
estimated that pollination services of honey bees are valued at $6 billion
annually. Because the alternatives are not as effective as EDB, there will be
some losses in pollination capacity resulting from the reduced nunber of
colonies. It is not possible to estimate the impact on pollination which could
result from the cancellation of SDB.
4. Fumigation of Stored Clothing and Furniture
Two products containing 5% EDB are registered for use in vault fumigation
to control clothes moths attacking furs, woolen garments, rugs, carpets, linen,
siohaiz-, or upholstered furniture. The directions for one product state, "Use
T-H Vault futaig<-it in a standard fumigation system, designed for evaporation of
a'.^iquid fumigant in a fur storage vault or de-mothing cabinet." This entails
pouring the liquid fumigant into a small flat container within the vault and,
depending upon the fumigant being used, placing the container near the ceiling
or on the floor. The fumigant then evaporates and the gaseous fumes fill the
vault to penetrate items being treated. Both product labels carry statements
of caution regarding handling and operator protection and safety. Also, both
products bear one or the other of the statements: "Not for household use" or
"For pest control operators only."
Four alternatives to SDB were found for this use. The first is a mixture
of carbon tetrachloride and ethylene dichloride in a ratio of 2 to 7. since
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carbon tetrachloride is undergoing RPAR review, this alternative is not
considered fully viable.
The second registered alternative is chloropicrin. It is a disagreeable
natarial with which to work, but this property tends to discourage mishandling
and exposure.
Methyl bromide is the third alternative. The three registered methyl
bromide products also contain 0.25 to 2% chloropicrin, as an odor warning
agent. For methyl bromide, the term "vault fumigation" would have to be
interpreted liberally, because the labels cite barns, storage buildings, and
other structures infested with these pests. Extreme care must be exercised
before applying methyl bromide, because it reacts with a number of organic
materials to produce foul-smelling odors. These materials include furs,
faather pillows, leather goods, and a variety of woolens.
The final chemical registered for this site/pest combination is sulfuryl
fluoride. Two products are registered, both containing 99% active ingredient.
This chemical, like methyl bromide, is released as a gas through copper tubing
from a pressure tank into the structure being fuaigated. The economic impacts
of EDB use on vault fumigation were not evaluated but are expected to be small.
5. Fumigation of Quarantined Plants, Soil and Grass Sod
The Japanese Beetle Domestic Quarantine program (7 CFS 301.48) requires the
treatment of regulated articles (including such material as soil, balled
plants and grass sod). Ethylene dibromide ¥440 (20% SDB), miscible ethylene
dibromide $434 (2.5% EDB), and methyl bromide are authorized fisnigants for
these regulated articles to control the Japanese beetle. Because chlordane has
been cancelled for all uses other than structural termite control and dipping
the roots and tops of non-food use plants, it is limited only to some uses
cited below. Therefore, methyl bromide is the single alternative used for
comparison.
Labels for these EDB-containing products do not specify that use be
restricted to certified applicators only, but do caution against inhaling,
swallowing, skin contact, vapors near eyes, or contamination with feed and food
stuffs.
Applications of ZDB and methyl bromide for each of these articles are
detailed below.
Grass sod; EDB #440 (20%) or *434 (miscible, 2.5%) is mixed at 20 cc £D3
to 1 gallon of water, sprayed over the sod and left to stand undisturbed for 24
hours. This amounts to 20 Ibs. of SDB per acre treated.
Methyl bromide is applied to cut, stacked, or rolled sod, under a tarp and
left to stand for 3 hours. The average rate of treatment is 2.5 Ibs a.i. per
1000 cubic feet or 60 pounds methyl bromide per acre under a tarpaulin.
3are root plants: ZDB #440 (20%) is mixed at 12 cc per gallon of water
and the plant roots ars soaked in the solution 24 hours. Methyl bromide
application is 2.5 Ibs/a.i. per 1000 cubic feet under a tarpaulin.
Plants Balled or _in Containers: £440 SDB (20%) is mixed at 2 cc per
gallon of water to be used as a dip or 2.5 cc per gallon of water to be poured
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on. Plants are then left undisturbed for 24 hours. There is also an injection
method which is not ordinarily used at the present time. At this rate, 1.65
Lbs. of EDB are used per 1000 cubic ft. of soil in balled and containerized
plants. Methyl bromide is applied at a rate of 2.5 Ibs. per 1000 cubic ft.
under a tarpaulin.
Pottina and bench soil: 50 cc of $440 is mixed in 3 gallons of water per
cubic yard of soil (55 cc in 6 gallons of water for high organic soil). The
soil is treated in 12 inch layers and soaked for 48 hours. Present annual
usage anounts to less than 50 gallons of the formulation. (USDA, 1978).
Methyl bromide is applied at a rate of 2.5 Ibs. per 1000 cubic feet for 3 hours
under a tarpaulin.
The economic impacts of the alternatives have not been evaluated.
Fumigation chambers or technology are not generally available to nurserymen who
are involved in this treatment on only an occasional basis.
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418-574 0-83-15
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212
IV. Identification of Regulatory Options
A. Introduction
As explained in Part I, FIFRA mandate's the Agency to weigh the health risks
and economic benefits of each use of a pesticide in order to achieve a balance
between these competing considerations. In Chapters II and III, the Agency
identified the risks posed by exposure to SDB and the benefits derived from
each of its registered uses. To achieve a risk/benefit balance, the Agency has
identified a number of regulatory options, and has evaluated each option for
its impacts on both sides of the risk/benefit equation.
In addition, the Agency has evaluated the risks of alternative
pesticideswhich have been identified as viable options for the various uses of
EDB.
This section identifies the regulatory options available to the Agency to
reduce the risks from the registered uses of EDB. The Legal authorities for
these options as provided in FIFRA are also discussed. In Chapter V of this
docunent, each option wj,ll be evaluated for its impact on the risks and
benefits of each registered use of EDB. These changes will then be compared to
determine the most appropriate regulatory option for the specific registered
use being examined.
B. Legal Basis for Options
FIFRA provides the Administrator with three broad legal courses of action
for the registration of a pesticide. These are cancellation, continued
registration without restrictions, and continued registration with restrictions.
Cancellation and continued registration without restrictions are opposite
courses of action which hinge on a determination that a pesticide does or does
not cause unreasonable adverse effects. To make this determination, the
Administrator weighs the risks and benefits of each use of a pesticide. If the
risks of a use outweigh the benefits, and the risks for that use cannot be
lowered, the use may be cancelled. If the benefits of a use outweigh its
risks, and any actions taken to reduce the risks result in a significant
reduction in benefits, the registration of that use may continue. In the case
of cancellation, the Administrator issues a notice of intent to cancel any or
all registrations off a pesticide (FIFRA Section 6(b)(1)]. This cancellation
notice becomes effective within 30 days, unless a registrant requests a. hearing
regarding its registrations. In the case of continued registration without
restrictions, the Administrator may publish a final SPAR position docunent
stating a rationale for choosing that course of action.
Between these polar alternatives of cancellation and continued registration
without restrictions exists a whole range of possible regulatory actions. In
fact, FIFRA requires ths Administrator to "consider restricting a pesticide's
use or uses as an alternative to cancellation...." [FIFRA Section 5(b)].
Although FIFRA does not specify what kinds of restrictions are to be examined,
the Agency interprets this to mean amending the terms and conditions of
registration in any fashion necessary to lower exposure (and consequently risk)
to the point that benefits are greater than the risks, and the reduction in
risks has not resulted Ln a significant reduction in benefits.
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C. Data Gathering for Identification of Options
In the process of varying the terms and conditions of registration, the
Agency can create an array of regulatory options intermediate to those of
cancellation and continued registration without restriction. In order to
facilitate the development of viable regulatory options, FIFRA provides the
Agency with certain legal "tools" to be used in the process of gathering
information on available options. The legal "tools" which FIFRA provides for
developing intermediate options are:
1. Additional data
Under FIFRA section 3(c)(2)(3), the Administrator may require a registrant
to submit any additional data necessary to maintain an existing registration.
When reviewing an RPAR pesticide, the Agency may identify areas in its risk and
benefit analyses where data are inadequate or totally lacking. The
Administrator may then require a registrant to provide specific data within a
certain time; if the registrant fails to comply, his- registrations may be
suspended.
2. Information-Gathering Hearings
If the Administrator is uncertain whether to cancel or restrict a
pesticide, s/he may publish a notice of intent to hold a formal hearing to
resolve the issue [FIFRA Section 6(b)(2)]. At the end of this hearing, the
Administrator makes a decision based on the hearing record. As an alternative
to a 'formal hearing, the Agency may conduct an informal' hearing to gather
information, [FIFRA Section 21(b)l and then use thac information co propose a
recommended decision.
D. Leaal Options Available Under FIFRA
The following regxilatory options are available to the Administrator under
FIFRA to reduce the risks from the registered uses of a pesticide:
1. Classification for'Restricted Use
FIFRA Section 3(d) enables the Administrator to restrict a pesticide's
use(s) if sxich use(s) cause unreasonable adverse effects. This classification
means that the pesticide may only be applied by or under the supervision of a
certified applicator, one who is trained and approved by a state as competent
to use restricted pesticides.
In classifying a pesticide for restricted use, the Administrator may also
propose other restrictions specific to each use of the pesticide. The
additional restrictions are aimed at reducing the risk to the general
population and applicators. These other restrictions are discussed in Section
E of this chapter.
2. Amend the Terms and Conditions of Registration
Under FIFRA Section 6(b)(1), the Administrator may offer the registrant the
option of voluntarily amending the specific registered uses of a pesticide for
which unreasonable adverse effects exist. Rather than to cancel all uses of
the pesticide, the voluntary change in classification would permit tha
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214
registration to be continued for certain uses which do not cause unreasonable
adverse effects and it would be cancelled for those uses where unreasonable
risks are present.
3. Labelling
FIFRA Section 3(c)(5) specifies that the label and labelling of a pesticide
must comply with the requirements of FIFRA. That is, the label must not have
use directions which result in unreasonable adverse effects. Consequently, the
Agency nay require a registrant to amend the label in order to keep the label
in compliance with FIFRA. Examples of label changes include requiring
protective clothing and/or respirators, warning applicators of the
toxicological hazards of the pesticide, altering the application fates or
methods, and other use or handling directions which are designed to reduce
applicator exposures.
4. Establish or Re-evaluate Tolerances in Con-junction
with FDA
Section 408 of the Food, Drug and Cosmetic Act requires that the
Administrator, under recomnendation from recognized experts qualified to
evaluate pesticides, establish a tolerance for residues of a pesticide on raw
agricultural commodities. Also, the Administrator may require that the
registrants submit data in the form of a petition for tolerance according to
the recommendations of an advisory committee.
The data required under Section 408 to establish a tolerance are:
(A) the name, chemical identity, and composition of the pesticide
chemical;
(B) the amount, frequency, and time of application of
the pesticide chemical;
(C) full reports of investigations made with respect to the
safety of the pesticide chemical;
(D) the results of tests on the amount of residue remaining,
including a description of the analytical methods used;
(S) practicable methods for removing residue which exceeds
any proposed tolerance;
(F) proposed tolerances for the pesticide chemical if tolerances
are proposed; and
(G) reasonable grounds in support of the petition.
Should the Administrator cancel certain uses of a pesticide, s/he may
revoke the established tolerance for that pesticide on tha basis of the data
supporting cancellation [40 CFR 180.32].
5. Cancel After a Specified Period of Time
If the Administrator determines that certain uses of a pesticide chenical
cause unreasonable adverse effects, then s/he would issue a notice of intent to
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cancel those uses. IS s/he also determines that there are no effective
pesticide or nonchemical pest control methods currently available as effective
alternatives to EDB, the Administrator could delay cancellation for a specified
period of time to allow for development of alternatives. Such a decision would
be implemented by issuing a notice of intent to cancel [FIFRA Section 6(b)(91)]
and by conducting a formal hearing if requested.
In summary, FIFRA provides the Administrator with several legal authorities
for regulating RPAR pesticides. With this legal foundation established, the
Agency next must explore possible technical use restrictions (i.e., amendments
to the terms and conditions of registration), and evaluate the extent to which
these restrictions would reduce the risks of SDB.
E. Risk Reduction Measures for EDB
1. CJse Restrictions for All CTses of EPS
This section presents the use restrictions which could apply to all uses of
EDB. The restrictions listed here are intended to reduce exposure to
applicators, other persons, and animals during and after fumigation. This
section is intended only to present all of the potential options developed by
the Agency, and not to indicate a decision to impose specific options.
Sections following this one present additional restrictions specific to each
use pattern. These additional restrictions are intended to reduce both
applicator exposure and food residue exposures.
a. Classify SDB for Restricted Use
Due to the chronic hazards posed by SDB, the Agency could classify this
pesticide for restricted use. Under this classification, only certified
applicators or persons directly under their supervision would use EDB. A
standard statement to this effect would appear on the label.
b. Protective Clothing
To prevent dermal contact with EDB, applicators could be required to wear
boot covers, disposable gloves and an apron during transfer of the pesticide
(i.e., pouring), during calibration or maintenance of application equipment, or
during clean-up of spills. These protective articles must be made of a
material resistant to EDB penetration. Butyl rubber is recommended for use in
gloves. Nitrile and polyethylene, while less resistent, are sufficient for use
in aprons, coveralls and boot covers where close body contact does not occur.
Articles made of natural rubber or leather should not be used. Contaminated
clothing should be removed immediately and exposed skin washed with soap and
water. Gloves and boot covers would be thrown away immediately if
contaminated, or after each use (not to exceed one hour) in any event. Other
clothing vjould be commercially laundered daily, or aired for at least 24
hours. All of these requirements would appear on the label.
c. Respirator
A respirator could be required to be worn at all times during application
and when reentering the treated site throughout the specified reentry period.
A full-face black canister gas mask approved by IJIOSK/MSHA for removing organic
vapors could be used. Applicators would be trained to properly wear, maintain.
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and store a respirator. The black canistor or charcoal filter is to be
replaces after each day or use. All of these requirements would appear on the
label.
d. Reentry Period
Before application, signs would be required to be posted at entrances to
the treated area (i.e., treated field or building) bearing the signal word
"DANGER," the product name, date of treatment, treatment period (if
applicable), the date when reentry is allowed, and what protective equipment is
required. The sign would remain posted during application and throughout the
period before reentry is allowed. The label would also contain this
information. Sample warning statement might read:
FOR OUTDOOR FUMIGATION;
DANGER
SOIL FUMIGATED WITH (PRODUCT NAME) ON
(DATE). DO NOT REENTER TREATED AREA UNTIL
(REENTRY DATE) OR^UNTIL EDB AIR LEVEL IS
LESS THAI! 0.4 PPM . WEAR A FULL FACE
BLACK CANISTER RESPIRATOR IF YOU MUST REENTER
THIS AREA BEFORE THE POSTED REENTRY INTERVAL.
FOR INDOOR (SPACE) FUMIGATION;
DANGER
PREMISES FUMIGATED WITH (PRODUCT NAME)
ON (DATE). TREAMENT PERIOD LASTS UTIL
(DATE). WEAR A FULL FACE, BLACK CANISTER
RESPIRATOR BEFORE REENTSRING PREMISES. AFTER
TREATMENT PERIOD, OPEN ALL WINDOWS, DOORS AND
VENTS. REENTRY WITHOUT A RESPIRATOR IS ONLY
PERMITTED AFTER 24 HOURS OF AERATION OR WHEN
EDB AIR LEVEL IS BELOW _0._4. PPM.*
* 0.4 ppm is the lowest level at which an IR detector alarm can sense the
presence of EDB. These detectors are available from the Foxboro Company,
Wilkes Infrared Center, S. Norwalk, CT.
e. Warning of Chronic Risks
The label would indicate that EDB poses a risk of cancer and mutagenic
effects to humans in addition to the acute effects already described on the
label. A sample sentence is:
"EDB HAS CAUSED CANCER, MUTAGENIC
EFFECTS AND REPRDUCTIVED DISORDERS
IN LABORATORY ANIMAL TESTS AND MAY
PRESENT TIIES2 HEALTH RISKS TO HUMANS".
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-' Other Safety Precautions
The label would also include statements expressing the following
requirements:
- Fumigation stay cake place only when personnel
will not be in the area (i.e., treated field
or building) during the treatment period and the
reentry period. Humans and animals must be vacated
from treatment area before fumigation;
- EDB may not be used or stored in domestic dwellings;
- Soap and water must be available for washing skin
or flushing eyes in case of contact with EDB;
- Hands must be washed before eating or smoking;
- Transferring activities (i.e., pouring) must be
conducted outdoors, unless a closed system of
transfer is used;
- Spills must be cleaned up immediately. If a spill
is on soil, cover with six inches of soil. If a
spill occurs on other surfaces, remove EDB with an
EPA-approved cleaning agent;
- Pesticide containers are disposed of by either
burying in a State-approved pesticide disposal
site or by returning them to a container
reprocessor;
- Containers or equipment made of aluminum,
magnesium, or their alloys must not be used,
because EDB will corrode them.
2. Additional Requirements for Soil Fumigation Uses
Reentry Period. Reentry without full-face, black canister
respirator into treated area will not be permitted until 24 hours after
fumigation is completed. This information would appear on the label and on
warning signs posted around treated areas. This requirement '*ould supersede
the minimum use restriction mentioned previously in that it proposes a specific
reentry time interval. The reentry interval is based on data indicating that
EDB level are below the level of detection at 24 hrs. after fumigation.
2. Additional Requirements for Stored Grain Fumigation
a. Restrictions for Reducing Applicator and
Reentry Exposure
1) Protective Clothing
EDB-resistant gloves (butyl rubber), boot covers and apron (butyl rubber,
nitrile, or polyethylene) would be required at all times during fumigation.
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This requirement would supersede the minimum use restriction of wearing
protective clothing only during mixing and loading, etc. The label would
describe this additional requirement.
2) Use Directions
Before fumigation, all leaks and vents in the grain storage structure
(e.g., bins, flats, elevators, boxcars or other storage facilities) would be
required to be sealed with masking tape, caulking or plastic. Humans would be
vacated from the structure to be treated. Only devices which apply the
fumigant quickly, evenly and with minimal vaporization would be permitted (such
as a sprinkling can without a nozzle or a coarse stream power sprayer). After
fumigation is completed, the treated structure would be sealed and all
entrances locked. The label would describe these requirements.
3) Reentry Period
After the treatment period has elapsed, a respirator could be required to
be worn upon reentry, all doors and windows opened, and aeration systems
activated (if available). Reentry without a respirator would be permitted only
after 24 hours of aeration or until an IR detector indicated a concentration of
EDB in air no more than 0.4 ppm. The label and posted warning signs would bear
this information.
4) Placarding- Treated Grain
Treated grain transported to another location would be placarded with a
sign indicating the date of last treatment. This sign could be removed at the
grain's destination. The purpose of this use restriction is to warn grain
inspectors and other workers of the previous use of a funigant in a particular
grain shipment. The label would include this restriction. As a further safety
measure, grain inspectors would use an IR detactor to determine whether
transported grain contained levels of EDB gas in excess of 0.4 ppm. If levels
were to exceed 0.4 ppm, grain would be held in quarantine at the elevator until
EDB gas measurements were below the 0.4 ppm level.
b. Restrictions for Reducing Food Residues
1 ) Reo-uire a Holding Period for Treated Grain
EDB slowly dissipates from treated grain held in storage. To allow EDB
residues to dissipate, the Agency will consider requiring holding periods of
30, 50, or 90 days for treated grain. If a holding period were imposed, it
would be stated on the label and on the placard that accompanied the
transported grain. Tolerances would be established, or changes in Labelling
would be made to enforce this requirement.
2) Prohibit "Off-Farm" Fumigations (Country Elevators,
Terminal Elevators, 3oxcars, Trucks, ,Mill Storage.
etc.).
Because "off-farm" use of EDB contributes about 3/4 of the dietary risk
from grain, the Agency could prohibit these uses. The only uses on grain which
would be permitted under this restriction would be "on-farm" fumigation of
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grain stored in warehouses, bins, or under tarpaulins. If this restriction
were imposed, it -would be required to appear on the label. Tolerances would be
revised or changes in labelling could be imposed to enforce this measure.
3) Prohibit "Off-?am" Use and Prohibit"On-Fanr." Treated
Grain from Being Used for Human Consumption
To eliminate direct dietary exposures of EDB through treated grain, the
Agency will consider prohibiting the use of treated grain for direct human
consumption. To ensure that this restriction is followed, registrants would be
required to add an FDA-approved dye to their products; grain treated with EDB
would then be discolored and identifiable as illegal for hunan consumption.
This requirement would have to appear on the Label. Tolerances would be
revised or changes in labelling could be imposed to enforce this measure.
4. Additional Requirements for Soot Treatment of
Milling and Cereal-Handling Machinery
a. Use Restrictions for Reducing Applicator
and Reentry Exposure
1 ) Protec-tive Clothing
SDB-resistant gloves (butyl rubber), boot covers and apron (butyl rubber,
nitrile, or polyethylene) would be worn at all times. The label would state
this.
2) Use Directions
Before fumigation, milling equipment would be run dry to minimize the
amounts of flour and grain parts left in the machinery. Persons not involved
with the fumigation would be vacated from the building. Only a "closed system"
hand-held applicator gun or an automatic dispensing system would be used to
apply EDB. Open pouring or pouring into bottles would be prohibited. After
completing fumigation, all windows, doors, vents and entrances would be locked
shut. These requirements would appear on the label.
3) Reentry Period
After the 24 hour treatment period, a respirator would be required to be
worn to reenter the building. All doors, windows and vents would be opened at
this time. Before anyone could reentar the treated building without a
respirator, the premises would be aerated 24 hours or until an IR detector
shewed that £03 air levels are below 0.4 ppm. The label and posted warning
signs would bear this information.
b. Restriction for Reducing Food Residues
Prohibit a Quantity of Contaminated Flour from 3eina tJsed for Human
Consumption. After spot treatment a mill could require several hours to start
producing flour of acceptable quality. This first batch of flour is normally
separated and then slowly fed back into the flour stream. Because a
significant portion of the EDB residues resulting from spot treatment occur in
this start-up batch, the Agency would require that the batch of flour be
discarded. This requirement would appear on the label.
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5. Additional Requirements for Pose-Harvest
Fumigation of Citrus and Tropical Fruits
a. Engineering and Operational Changes for
Fumigation Facilities.
The Animal and Plant Health Inspection Service (APHIS) of the U.S.
Department of Agriculture (USDA) regulates all fumigation centers in the U.S.
and two centers in Mexico. APHIS regulations and its treatment manual would be
revised so that each fumigation center meets a standard of a maximum
permissible level of EDD concentration in air of 0.4 ppm (15 min. avg.). To
meet this standard, APHIS could implement any of the following risk reduction
measures to achieve the air standard in addition to those which appear on the
label (See Section IV. S. above):
-Closed dispensing system (EDB-resistant tubing with soldered
connections), including an air coupling (with which to purge the line
before opening it), and a pressure relief valve. Valves would be designed for
handling SD8.
-Air monitoring device with an I'R detector connected to an alarm and
calibrated to be triggered if the EDB1air levels in the hallway exceed 0.4 ppm.
-Ventilation system would be adj usted so that there is greater
pressure in the hallway than in the fumigation chamber.
-Training of applicators in all aspects of fumigation procedures,
protective equipment, safety precautions and emergency plans.
-Testing of fumigation chambers for leaks before ths USDA inspector
approves a fumigation permit.
-Restarting exhaust fan after opening chamber door to move EDB vapors away
from workers.
-Monitoring of personnel to detect EDB exposure levels on a scheduled
basis.
-Posted operating instructions and emergency procedures.
b. Requirements for Warehouses Holding
Treated Commodities.
APHIS is responsible for reducing exposures that result from treated fruit
as it is transported or stored. Because high exposures have been detected
during warehouse workers' handling of treated fruit, APHIS could require these
warehouse futilities to meet the standard of 0.4 ppm EDB in air. This would
involve:
-Monitoring of personnel to detect EDB exposure levels on a scheduled
basis.
-Installation of ventilation systems in warehouses adequate to ensure that
exposure does not exceed 0.4 ppm.
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-Installation of detection/alarra devices in warehouses calibrated for 0.4
open.
-Requiring full-face, black canister respirators for all personnel who are
exposed to EDB air levels higher than 0.4 ppn. (For instance, the "stickmen"
who unload treated citrus from trucks would have to wear a respirator unless
the cardboard containers are eliminated.)
-Replacement of cardboard citrus boxes with a bulk loading system made of a
non-SDB-absorbent material. (This requirement would be optional. However, a
bulk loading system may reduce exposure to less than 0.4 ppa and thereby
eliminate the need for workers to wear respirators.)
-Training of all warehouse personnel about hazards of EDB, methods for
reducing exposure, and emergency procedures.
-Signs would be posted in warehouses stating:
WARNING - FUMIGATED FRUIT MAY SHIT HARMFTE, STHYLSNE OIBRCMIDS
VAPORS. IF AIR LEVELS BECOME HAZARDOUS AND ALARM SOUNDS, PUT CM
FULL-FACE BLACK CANISTER RESPIRATOR IMMEDIATELY.
c. Restriction for Reducing Food Residues
Require treated fruit to be stored for a specific period. One approach to
reducing SDB residues in treated commodities is to lengthen the treatment-to-
market interval by requiring treated fruit to be stored for a certain period
after treatment. Based on the available data the Agency has estimated a
degradation formula for EDB residues in treated fruit. Using this formula for
citrus, SDB residues are estimated to decrease from 8 ppm to 1.42 ppm during a
six-day treatment-to-market interval. If this treatntent-to-market interval
were lengthened, EDB residues could be further reduced. TO explore the
feasibility of this approach the Agency could require APHIS to hold treated
fruit from commerce for a certain time period. This requirement would be
stated on the label.
6. Additional Requirements for Fumigation of Beehive Supers
a. Use Restriction for Reducing Applicator and
Reentry Exposure
1) Protective Clothing
The label vould state that EDB-resistant gloves (butyl rubber) , boot covers
and apron (butyl rubber, nitrile or polyethylene) would be worn at all times.
2) Use Directions
Hives and/or combs (supers) would be placed in a gas-tight room or under a
gas-tight covering such as a polyethylene tarpaulin held down with sand-filled
"snakes". All windows, doors and vents would be sealed. All persons not
involved with the funigation would be vacated from the building. The label
would state these directions.
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3) Reentry Period
Following the treatment period, a full-face black canister respirator would
be worn when reentering. All doors, windows and vents must be opened at this
time. Aeration for 24 hours or until EDB air levels are less than 0.4 pom,
measured by IR detector, shall be required before reentry is permitted. The
label and warning signs would contain this information.
b. Restriction to Avoid Food Residues
Limit_fumigation to beehive supers that are clean and in storage. To
avoid possible contamination of honey or honeycombs, the label would prohibit
treatments other than on clean supers in storage. This restriction is in
accordance with current practice.
7. Additional Requirements for Vault Fumigation of
Stored Clothing.
a. Use Restrictions for Reducing Applicator and
Reentry Exposure
1) Commercial Use Only
Vauiz funigation would be conducted only by certified commercial
applicators in commercial clothing storage .vaults. The label would stats this.
2) Use Directions
Before fumigation all doors and leaks in the vault would be sealed. All
persons not involved with the fuaigation would be vacated from the building.
This requirement would appear on the label.
3) Reentry Period
Following the treatment period, a full-face, black canister respirator
would be required to be worn during, reentry. All doors and vents in the
treatment area and connected buildings would be opened at this time. Premises
would be aerated 24 hours or until the EDS air level is less than 0.4 ppm
increased by an IR detectoc, before reentry is allowed. The label and posted
warning signs would contain this information.
8. Additional Requirements for Fumigation of
Subterranean and Drywood Termites
a» Qse Restrictions for Reducing Applicator and
Reentry Exposure
1) Certified Applicators
Fumigation would be carried out only by certified commercial applicators.
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2) Protective Clothing
EDB-resistant gloves (butyl rubber), boot covers and apron (butyl rubber,
nitrile, or polyethylene) would be required at all times. The label wou!4
state this.
3) Use Directions for Dryvood Termites
Persons not involved with the funigation would be required to be vacated
from premises. Holes of size and spacing specified by the registrant should be
drilled and the recommended dosage of EDB inj ected into these holes using a
calibrated syringe or like device. The label would state these requirements.
4) Use Directions for Subterranean Termites
Persons not involved with the fvmigation would be vacated from premises
before fumigation and subsequent aeration. Use would not be permitted under
slabs which contain air ducts, electrical conduits, or the like. Recommended
dosage would be inj ected through holes drilled in concrete slabs which support
infested structures. All holes would be plugged temporarily to prevent the
escape of SDB during treatment, and would be sealed permanently immediately
after treatment. The label would state these requirements.
5) Reentry Period
During.and after fumigation all doors, windows and vents in the treatment
area and connected buildings would be opened. Premises would be aerated 24
hours or until EDB air levels are below 0.4 ppm before reentry would be
permitted. The label and posted signs would contain this information.
9. Additional Restrictions for Fumigation of Bark Beetle
a. C7ae Restrictions for Reducing Applicator and
Reentry Exposure
1) Protective Clothing
EDB-rssistant gloves (butyl rubber), boot covers and apron (butyl rubber,
nitrile or polyethylene) would be required at all times. The label will state
this.
2) Use Directions
SOB would only be applied to infested, failed logs by spraying recommended
dosage onto stacked logs, immediately covering the stack with heavy plastic,
and sealing this cover with sand snakes. Signs would be posted on the treated
stacks stating when the cover could be removed. Spraying logs in the open
without an approved covering would be prohibited.
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10. Additional Restrictions for Fumigation of
Japanese Beetle Under USDA Quarantine Program
a. Restrictions for Reducing Applicator and
Reentry Exposure
Under the authority of the Organic Act (7 C.S.C. 147a), the APHIS program
of USDA has established a Japanese beetle quarantine program which requires
fumigation of certain regulated articles (such as infested plants, grasses or
soil) before they can be shipped out of a quarantined area. The APHIS Japanese
Beetle Program Manual specifies the approved pesticides and treatment methods.
A review of this manual indicates that it could be revised to include the
a-forementioned minimal, use requirements. Further, a review of the two
currently registered labels for this use (registration numbers 1681-6 and 3743-
263) shows that these labels could be upgraded to describe all the usa
restrictions and directions for this use pattern. Following are the additional
use restrictions or revisions in the APHIS Manual developed by the SPA for each
regulated article:
1) Grass Sod
Treated sod would be required to be covered with a heavy plastic or tarp
during the treatment period to ensure an sfficacious treatment and to minimize
air exposures. The tarp would be required to be aired before re-use.
2) Bareroot Plants
The proper method for disposing of the used EDB-water mixture would be
specified.
3) Balled or Containerized Plants
The "enclosed place" into which plants are placed after treatment would be
posted with signs indicating the minimal reentry information described
previously. Proper disposal methods would be described.
4) Potting and Bench Soil
Soil would be covered with plastic or heavy tarp for the duration of the
treatment period.
5) Beds and Other Uses
Soil would be covered with plastic or heavy tarp for the duration of the
treatment period.
6) For All Above Uses
The APHIS Manual states for balled or containerized plants that treatment
is approved only when beetle grubs (larvae) are present. This requirement
would be imposed for all regulated articles to avoid unnecessary applications.
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V. SELECTION OF REGULATORY OPTIONS
A. Introduction
The purpose of this chapter is to determine the most appropriate regulatory
options the Agency should propose for each registered use of EDB. to
accomplish this, the risks to hunan health and the environment for each
registered use are systematically compared with the benefits which result from
that registered use. If this comparison demonstrates that "unreasonable
adverse effects" to man or the environment exist for particular uses, then
specific regulatory options are developed to reduce the risks for each of those
uses. The Agency then evaluates the extent to which these regulatory options
will change the risks and benefits of each use of EDB. Finally, by comparing
the changes in the risks and benefits the Agency selects and proposes the nost
appropriate regulatory measure for each use of EDS.
In previous chapters of this docunent, the Agency has evaluated both the
risks and the benefits which exist as a result of the currently registered use
practices of EDB. In addition, the Agency has sumnarized the regulatory
options which are available under FIFRA.
As discussed in C'.-.apter II of this docunent, the Agency has examined all of
the available health studies on EDB. These studies include investigations of
possible carcinogenicity, mutagenicity, and reproductive disorders. After a
careful review and evaluation of these studies, qualified Agency scientists and
outside consultants have reached several conclusions regarding the possible
hazards which may result from exposure to EDB.
Based on the accumulation of evidence, the Agency considers EDB to be a
potent animal carcinogen and a probable human carcinogen. Because the
pesticidal uses of EDB result in hunan exposure during application, through
contamination of some foods during application, and during transport of treated
commodities, the Agency concludes that EDB poses a risk of cancer to hunans.
The Agency also concludes that EDB causes reproductive disorders in bulls, rats
and chickens, suggesting that repeated exposure to EDB may cause reproductive
disorders in humans. Finally, the Agency concludes that adequate raultitest
evidence exists to demonstrate that EDB also causes ntutagenic effects in
several organisms. This evidence indicates that exposure to EDO poses a
potential risk of genetic damage to man. Collectively, these three conclusions
confirm qualitatively that hunan exposure to EDB poses substantial risks to the
public health.
The Agency has quantitatively estimated the cancer risks to the public
which exist due to current registered use practices. Animal toxicity data and
the human exposure estimates were used to evaluate the lifetime probability of
EDB-induced cancers to the general population and to occupationally-exposed
workers. Probability estimates, based on total dietary exposure resulting from
pesidues persisting in EDB-fumigated commodities, range from approximately 10
to 10 . Applicator risk estimates range from 10 for soil fumigation
operators to 0.4 for some persons involved in the fumigation ofcitrus.
The Agency has determined that human exposures to EDB also pose a risk of
nutagenic effects and reproductive disorders to exposed individuals. The
Agency has not quantitified the risk of mutagenic damage to exposed
individuals, but has concluded that these risks exist and must be taken into
consideration in determining the most appropriate regulatory actions. Based on
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the NCSL for reproductive disorders observed in rats (as well as the repro-
ductive disorders observed in bulls) and based on the applicator exposure
levels, the Agency has also determined that an adequate margin of safety does
not exist. Although the Agency does not plan to perform a quantitative risk
assessment for reproductive disorders, it will propose regulatory options that
should provide an adequate margin of safety by significantly reducing exposure.
Benefits resulting from the use of EDB, summarized in Chapter 4 of this
docunent, are estimated to be approximately 60 million dollars per year. Of
the estimated fifteen million pounds of EDB used annually, over eleven million
pounds are used for soil fumigation. However, the largest economic benefits of
EDB use do not result from its use as a soil fumigant but result from a
significantly lower volume use - the USDA APHIS quarantine program. This
program requires that in certain geographic areas citrus and certain other
commodities be funigated with EDB prior to transport in order to prevent the
spread of fruit flies into geographic regions where they are not established.
While this program accounts for less than one percent of the annual EDB usage,
it can account for over 30% of the benefits of ED3, an estimated 24 million
dollars annually.
It is for reasons such as this that each major use category is system-
atically analyzed in the following pages using these and significant factors.
For a given use category, the risks and 'benefits are reviewed and the data gaps
identified. The significant hxinan health risks are then weighed against the
corresponding benefits and a judgment is made as to whether or not the risks
outweighed the benefits. If regulatory actions are required to reduce these
risks, an analysis is then made of the extent to which each available
regulatory action might reduce the risks. The most reasonable regulatory
measure is identified and proposed for that use category.
3. Fumigation of Stored Grains
1. Summary of Risks and Benefits
The Agency has determined that the general population, grain fumigation
applicators, and individuals handling EDB-fumigated grains are at risk to
health hazards as a result of exposure to 2DB. The risks include cancer,
nutagen'ic damage, and reproductive disorders. As discussed in Chapter II, the
Agency has concluded that residues of SDB persist in flour, baked breads, and
other baked flour products made from wheat fumigated with EDB. The range of
expected residues which the Agency has determined occur in bread baked from
this flour vary from 0.07 ppb to 38 ppb. Based on these residue levels, the
Agency has estimated that the lifetime risks of EDB-induced cancer^to the_4
average U.S. citizen on a typical diet vary from approximately 10 to 10
for this registered use. Although the Agency has not quantitatively estimated
the public's dietary risk of mutagenic damage and reproductive disorders, it
has concluded that these combined risks warrant consideration of additional
regulatory actions.
The Agency has no monitoring data on exposure to EDB for individuals who
fuaigate stored grains. However, based on available exposure data from similar
use prac-.ices for other grain fumigants, the Agency has concluded that grain
fumigant applicators are exposed to EDB through dermal contact and the
inhalation of ECB vapors. Mixing, loading, use, and storage of SDB-containing
grain fumigants can expose applicators and individuals in the immediate
vicinity to SDB vapors. Commonly occurring spills of these fumigants on skin
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or clothing also result in dermal contact: for applicators. As a result of
these exposures, about 50,000 eo 60,000 applicators and "non-involved" persons
are potentially at risk, to the health hazards of EDB.
In addition to the above risks, persons involved in the transport or
handling of ED8-fumigated grains as they move through commerce (dock workers,
grain inspectors/ etc.)are potentially at risk to the health hazards of EDB.
These risks result in people being exposed to vapors which have slowly
dissipated from treated grains and which have been trapped in storage or
transport systems. The Agency has no exposure data for this occurrence and has
not estimated the number of people exposed in these situations. The Agency has
determined that the health risks resulting from these exposures, should be
considered in the selection of an appropriate regulatory action for this use.
Bystanders in the immediate area of use or transfer of EDB grain storage
fumigants can also be exposed to SDB vapors. The Agency has not evaluated the
exposure to these individuals in its quantitative risk estimates because of a
lack of needed data. There are no estimates of the number of persons exposed,
but the Agency recognizes that such exposure can occur and would be attended by
health risks which should be considered in the development of a proposed
regulatory position.
The Agency has evaluated the economic benefits of grain fumigation with SDB
and has determined that on a national basis there would be no adverse economic
impacts if EDB were cancelled; in fact, users would save money by using
alternative pesticides. As discussed in Chapter III, EPA has determined that
certain available alternative funigants, if used properly, are more economical
and that, on a national basis, farmers would save approximately 0.5 to 2
million dollars by using them. These alternatives, which will be examined in
detail later in this section, are aluminum phosphide and a mixture of carbon
tetrachloride and carbon disulfide.
These savings tend to obscure the fact that under certain conditions there
are advantages in using EDB. Grain storage facilities, which allow furaigant
vapors to dissipate easily because the storage facility is not well-sealed, may
be berter suited to EDB due to its characteristic persistence. However, the
Agency has concluded that, in most cases, the alternatives will be more
economical.
If EDB were cancelled, the most likely substitutes would be a mixture of
carbon tetrachloride and carbon disulfide at on-farm storage facilities, and
aluninium phosphide at off-farm storage centers. Because on-farm and off-farm
facilities vary widely in airtightness, the substitutes also vary — the
tighter the facility, the more likely it is that the substitute would be
aluminum phosphide. This grain fumigant is less costly but requires a well-
sealed storage facility and a longer exposure period to be effective.
2. Risk/Benefit Analysis
Based on the above risk and benefit information, the Agency has concluded
that the risks exceed the benefits for EDB funigation of stored grains. Thus,
risks of unreasonable adverse effects to the public health axist and will
continue to exist unless regulatory actions are implemented to reduce
oreliminats these risks. This conclusion is based mainly on potential dietary
-97-
418-574 O - 83 - 16
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228
risks and the estimated negative economic benefits. It is supported by the
potential health risks to grain funigant applicators, individuals who handle
£C3-fumigatad grains, and non-applicators who may be exposed to EDB vapors
during storage, transfer, or use.
Accordingly, the Agency has evaluated several regulatory options which
night reduce these risks. Table 29 displays the impacts which each regulatory
option would have on human health risks resulting from exposures to EDS, the
health risks of the likely substitutes for this use of SDB, and the expected
economic inpacts.
All actions short of immediate cancellation would result in continued
dietary risks. Options 2 and 3, "Classify for Restricted Use" and "Restricted
Use Classification Plus Changes in the Terras and Conditions of Registration"
•would result in some reduction in applicator and dietary risks because some EDB
users might voluntarily switch to alternatives. However, only immediate
cancellation would eliminate all EDB dietary and inhalation risks. Because
unreasonable dietary affects continue to exist for all options less restrictive
than immediate cancellation, the Agency has concluded that immediate
cancellation of this registered use of EDS is necessary. Immediate
cancellation is further supported by the availability of alternative funigants
which are less expensive and which the Agency considers will pose less risk to
applicators and the public when compared to EDB.
To reach determinations about the risks of the alternatives, available
health effects-related studies on these chemicals were reviewed with these
results:
Ose of aluminum phosphide in not expected to result in unreasonable risks
to applicators or the general public. Aluninun phosphide has an established
tolerance for many food products including grains. This chemical rapidly
reacts with water in air resulting in the release of phosphine gas and a
residue of aluminum hydroxide. It is this gas which actually destroys insect
infestation. Because phosphine is a highly reactive and fugitive gas, residues
on commodities or treated materials are not expected. Phosphine is acutely
toxic and poses a risk to unprotected applicators. If the precautions
specified on the label are followed explicity, applicators, should be
adequately protected. Aluninum hydroxide, a common ingredient in antacids,
does not appear to pose a health hazard, as determined by an FDA review of
toxicology data.
Carbon disulfide (CS ) is an acutely toxic, highly flammable and
penetrative liquid. It LS formulated in a mixture with carbon tetrachloride
and other fvmigants to reduce its flammability. Adequate toxicological data
are* not available to determine if carbon disulfide poses chronic hazards to
hunans- Likewise, no studies have been conducted to determine whether residues
of CS might occur in food. Though CS is exempt from tolerances for
grains because residues were not expected to occur in food or feed, the Agency
considers it prudent and is initiating a study to determine if any residues of
CS can be detected in grain or flour. If residues are found, registrants of
CS may be required to submit chronic feeding studies.
The third major alternative pesticide is carbon tetrachloride. *Tow under
RPAR review, CC1 has been presuned to present a risk to hunans of cancer,
chronic liver effects and chronic kidney effects. CC1, is also suspected of
inducing mutagenic and teratogenic effects in laboratory tests.
-98-
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Tab la 29 lapacta ot HayuUtory Optlonu on Stored Grain*
ID
Ho>jul<>tory Option
1. Cuiitlnuutl
Hdijlatratlon
EI)U Human llo* 1th
K*l>oa\>r* tout*
Inhalation, Our mil
Dietary
Hlaka Kink of Uubutltutau
Mlukit lUiann/EnvlroniBontAl
Boo Table* IB and 20 Not applicable
(or concur rlaka and
dlucuiulon in Chapter II
toe other po««lblo rlaka
Economic Impact*
Uuera
Hone
Conauaara
Nona
Cuauaenla
Unreasonable
dietary, duruul
and Inhalation
rl*ka cuntlnua
(or
HoutrtutuU Uu« and
A. Prutactiva E
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230
However, the cancellation of EDB is not expected to increase the health
risks of CC1 , because exposures to CC1 are not expected. The ECB mixture
which is applied to grain, is formulated* with CC1. and other liquid
fumigants. The concentration of CC1, in these mixtures usually ranges
between 70% and 90%. If ECB is cancelled, the predominant substitute is a
mixture of 30% CC1,, and 20% CS_. Thus, roughly the same amount of CC1.
is contained in the substitute mixtures. As a result, exposure to CC1. would
not be expected to increase.
In STjnmary, from the available information, the Agency concludes that,
aluninum phosphide and carbon disulfide used according to labeled safety
precautions, will not pose the range or magnitude of adverse health effects to
users and to the public that the use of SDB poses. Once cancellation is
effective, the Agency will initiate action to revoke the current exemption for
grain from tolerances for EDB.
The Agency must act to reduce the unreasonable risks posed by SDB.
Cancellation is the most effective and viable option in light of the high risks
of EDB and the fact that the alternative fumigants, which are less expensive,
are just as efficacious and will not pose the range or magnitude of adverse
health effects to users or the public as demonstrated for EDB. This decision
is enhanced by the recent development of carbon dioxide, nitrogen and
combustion product gas as effective means of controlling pests in stored
grain. If these gasous insecticides are exempted from tolerances and prove to
be technically and economically feasible, they will be additional alternatives
to EDB.
C. gjARANTTSE FUMIGATION
1 .. Summary of Risks and Benefits
As discussed in Chapter II, over 99% of the EDB used for quarantine
purposes in 1977 was applied to citrus and tropical fruits (35,000 Ibs.) and
the remaining amount (300 Ibs.) was applied to miscellaneous fruits and
vegetables. The Agency has determined that both the risks to human health and
the economic benefits which result from this registered use may be
substantial. The Agency is concerned that the estimated benefits may
substantially overstate the economic value which results from current use
practicas for this registration. This issue and the fact that there are
currently no registered chemical or approved nonchemical alternatives for this
use have complicated the Agency's decision as to what regulatory action to
propose for the use of EDB in quarantine fumigation.
In Chapter II, the Agency established that significant human health risks
are present as a result of current EDB use practices in quarantine fumigation
programs. These include risks to the health of the general public through
exposures to EDB residues persisting in treated commodities, and health risks
to occupationally-exposed individuals, including those working at or around SDB
fumigation centers and those working in warehouses where fumigated commodities
are temporarily stored. The health risks are cancer, mutagenic effects, and
reproductive disorders.
The Agency has quantitatively estimated the lifetime cancer risks to the
general public and has established that significant cancer risks result from
current practices at quarantine fumigation centers. The residue estimates
forming the basis of estimated risks are supported by chemical analyses of EDB
residues which were found in commodities obtained from retail grocery stores.
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231
As discussed in Chapter II, che Agency has determined chat the lifetime risks
of EDB-induced cancer to the general public range from approximately 10 for
citrus to 10- for tropical fruits.
The Agency has also determined tha lifetime risks of cancer for persons
occupationally exposed, including fumigation center employees, truckers
involved in the transport of fumigated commodities, and persons involved with
the movement and handling of fumigated commodities into and out of warehouses.
As discussed in Chapter II, the Agency has estimated the cancer risks to
fumigation center employees to vary from approximately TO to 10 , to
warehouse workers,from approximately 0. 1 to 0.4, to outdoor operators of
approximately 10 , and to truckers of approximately 10 . These cancer
risks are among the highest risks the Agency has ever confronted.
In addition to these quantified risks, the Agency has also concluded that
adequate evidence exists to demonstrate that SDB causes mutagenic effects in
several organisms and reproductive disorders in exposed animals. Though the
numerical range of the risks of these health hazards is not available, the
Agency has concluded qualitatively that humans exposed to SD3 are also at risk
to genetic damage and reproductive disorders. These additional risks, together
with the cancer risks, demonstrate that the use of EDB in APHIS quarantine
programs poses unusually high health hazards to the general public and to
occupationally exposed workers.
The benefits resulting from this use of SDB, discussed in Chapter III, may
amount to as much as 25 million dollars annually. This estimate is based
largely on the assumption that if this registration were cancelled, the
grapefruit export market to Japan would be eliminated, resulting in a loss to
Florida growers of about 29 million dollars in revenue. However, this loss
would be partially offset by an increase in the value of domestically produced
mangoes and papayas, and also by the decrease in treatment costs.
It should be noted, however, that the estimated benefits from this use may
be substantially overstated because they are based on the assumption that the
grapefruit export market to Japan will be lost if this registered use is
cancelled. The Agency recognizes that this export market was established on an
understanding between the U.S. and Japan that grapefruits and certain other
citrus destined for Japan from Florida will be treated with ED3 prior to
shipment as a quarantine measure against the spread of fruit flies. The loss
of this export market rests on the assumption that if this registered use of
SDB were cancelled, the Japanese would no longer accept Florida's citrus
because it had not previously been treated with SDB. One possible option is to
cancel the use of EDB on crops destined for consumption in the Q.S., and allow
its continued use on crops designated for export to Japan. However, it may
happen that the Japanese government will decide that SDB fumigation is
unacceptable and will not allow EDB-treated grapefruit and citrus to be
imported. Thus, the actual impacts of cancelling this use of SOB depend on
whether or not the Japanese will continue to require EDB treatments.
The underlying assumption that there are no viable alternatives to SDB for
this use also has direct bearing on the estimated economic impact of cancelling
SDB. There are no registered chemical alternatives for this use of SDB, nor
are any -approved non-chemical treatment methods presently available. Heat
vaporization ccoks the fruit, giving it an "off taste; furthermore, there are
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232
no known available commercial vapor-heat chambers. Cold treatment damages
grapefruit and other citrus; it cannot be used on mangoes or papaya, and causes
a loss of about 10 percent in other miscellaneous fruits and vegetables.
However, gamma irradiation, a non-chemical method, is a promising
substitute for £DB post-harvest funigation. In many countries, irradiating
foods with gamma radiation has been shown to be an economical, effective and
safe method for eliminating pests from fresh foods. A number of foreign
countries, including Japan, have approved and are using gamma radiation for
food preservation and/or insect disinfestation. Appendix 2 lists the status by
country of the acceptability of food irradiation. In the U.S., irradiation is
subj ect to approval of the Food and Drug Administration (FDA) under the
authority of the Food, Drug and Cosmetic Act. In fact FDA has already approved
its use on for use on white potatoes and wheat (21 CFR 179.21). The Agency has
had numerous meetings with both FDA staff and food irradiation experts to
determine if irradiation of citrus should be considered as a potential
substitute for this use of EDB. As a result, the Agency has concluded that
irradiation is a potential substitute and should be a factor in developing a
regulatory decision. This conclusion is based both on the Agency's recent
discussions (Williams, 1980a and b; Savinski 1980; Welt, 19SOa and b; Seeder,
19SOa) and on recommendations made by the Interdepartmental Committee on
Radiation Preservation of Food (ICRPF) in their report entitled, "Food
Irradiation in the United States" (December, 1978).
Thus," the impact of cancellation of this use of EDB also depends on FDA
approval of the use of gamma radiation as an insect disinfestation method for
citrus and tropical fruits, as well as on Japan's acceptance of this substitute
method. If the FDA approves and the Japanese accept irradiation of citrus *s
an alternative to EDB, then the current estimates of the benefits for this use
of SDB may be significantly reduced. However, the Agency has not thoroughly
studied the economic impacts of the use of irradiation.
2. Risk/Benefit Analysis
The Agency has evaluated the risks to human health and the economic
benefits which result from current use practices and has concluded that this
use causes unreasonable adverse effects to humans. Regulatory options
available to the Agency to reduce these risks are listed in Table 30. This
table shows the expected changes in risks and benefits which result from the
implementation of each regulatory option.
Option 1, continued egiatration, would result in the indefinite
continuation of unreasonable adverse effects both to the general population
front dietary exposure and to workers applying EDB or handling treated fruit.
The benefits of this use of EDB, approximately 25 million dollars annually,
would remain unchanged.
Under Option 2, the Agency would impose restrictions to reduce risks for
truckers, employees at fumigation centers and warehouse workers. Various means
of reducing dietary exposure to the general population were explored in Chapter
IV, however, none were considered to be effective or practical. Consequently,
this option would only reduce risks to persons occupationally exposed to EDB.
Risks to the general public would continue indefinitely because this option
-102-
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233
would have no impact on residues in citrus and tropical fruits. The benefits
resulting from implementation of this option would remain essentially the same
as in Option 1, because costs to impose ehfl restrictions are small, about
13,000 cer facility. (See Table 30).
Option 3 would permit SDB use to continue until a specific date. During
the period of continued use, the restrictions specified in Option 2 would be
imposed. Because there are currently no effective registered alternatives to
EDB, selection of this option would allow for the development and
implementation of alternative safer methods for use on quarantined commodities.
With implementation of this option the risks and benefits would-change as
the restrictions imposed change. The immediate impacts on risks and benefits,
which would last until cancellation became effective, would be the same as
those under Option 2 (i.e., reduced risks to applicators, continued high
dietary risks to the general public, and essentially unchanged high economic
benefits). Once cancellation became effective all SDB health risks would be
eliminated, both to exposed applicators and to the general public from dietary
exposure to EDB residues in treated commodities. The economic impact of
cancellation, if gamma irradiation or another alternative became available,
would be the capital investment costs, amortized over an appropriate period of
time, plus the operating costs/ minus the costs of treatment with EDB. The
Agency has not examined these costs in detail, but has obtained some
preliminary estimates of the operating costs for an irradiation facility with
the capacity for effectively eliminating fruit flies on about 4 million pounds
of packaged citrus per day (Welt, T9SOa). At a minimum dosage level of 25
Krad, not to exceed 50 Krad, the estimated cost of processing is between 552
and $90 per 40,000 Uss of citrus. This cost estimate is based-on 100,000 cases
of grapefruit containing 40 Ibs per case. Costs of the implementation and use
of gamma radiation as a pesticide have been studied in great detail in a report
entitled "Food Irradiation in the United States", prepared by the
Interdepartmental Committee on Radiation Preservation of Food (December,
1980). Conclusions from this report were that "Use of chemical pesticides such
as ethylene oxide, methyl bromide and ethylene dibromide could be reduced or
eliminated."
Option 4 is immediate cancellation of the use of EDB to treat commodities
destined for consumption in the U.S., while permitting its use to continue for
fumigation of commodities destined for export, and requiring the same
restrictions as would be imposed by Option 2 to reduce applicator risks. This
option has three possible outcomes. The impact on risks and benefits depends
on the possible outcomes. Under this option, dietary risks to the U.S. public
would be eliminated and the risks to fumigation center and warehouse employees
'would be reduced. The economic impacts of this option could be highly variable
depending on which outcome results. One outcome is that the Japanese
government could continue to accept imported citrus which as been treated. If
this outcome were to occur, the reductions in benefits could be small under the
first outcome, amounting to an estimated $1.6 million. A second outcome of
Option 4 is that the Japanese might decide to refuse EDB-treated citrus, in
which case the economic loss to growers and the U.S. balance of trade would be
large ($25 million and S27 million, respectively). A third possible outcome is
that the U.S. could substitute gamma irradiation for EDB and still retain the
Japanese export market. In this case, the economic impact on growers would be
a change in treatment costs which the Agency has not evaluated.
-103-
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234
Option 5 is immediate cancellation of all EOB used for post-harvest
fumigation. This option would have significant impacts on both the risks and
benefits of EDB. All risks of EDB would be immediately eliminated. Because
the export market to Japan would be lost, the Agency estimates that citrus
growers would lose S2S million in revenue losses and that there would be a net
$13.4 million loss in the U.S. balance of trade.
Upon evaluation of the impacts each regulatory option has on the risks and
benefits, the Agency has concluded that Options 1, 2 and 4 should be eliminated
from further consideration and that only Options 3 and 5 should be examined in
more detail. The reasons for eliminating the three options are as-follows:
Option 1—continued unrestricted use—would result in the continuation of .
unreasonable adverse health effects to the general public, to the occupation-
ally exposed worker including fumigation center employees, warehouse workers,
and truckers, and to those individuals living around fumigation centers.
Option 2—classifying for restricted use and requiring fumigation center
and warehouse modifications—would reduce the risks to workers through the
implementation of these measures. The benefits would remain essentially
unchanged. However, risks of unreasonable adverse effects to the U.S.
population through dietary exposures to EDB would continue.
Option 4—immediately cancelling the use of EDB to fumigate commodities
destined for consumption by the U.S. public, while retaining its use to
fumigate commodities intended for export to foreign markets and imposing
measures to reduce U.S. worker risks—would eliminate all dietary risks to the
U.S. public and would reduce U.S. workers' risks. However, this regulatory
option would announce to the international community that the Agency has not
attempted to reduce the potential dietary residues and health risks which may
be faced by countries importing U.S. treated commodities. The Agency views
this option as a poor approach to the solution"of an international
environmental problem. The Agency rejects this option as an acceptable
alternative.
The Agency has conducted an intensive comparative evaluation of the risks
and benefits resulting from the implementation of Options 3 and 5.
Option 3—cancellation on a specific date of all uses of EDB to fumigate
quarantined commodities, and in the interim requiring measures to reduce worker
exposure—would allow the benefits of this use to continue until the date when
cancellation becomes effective. The EDB health risks to workers would be
reduced in the interim, while the benefits of approximately $25 million
annually in revenue would be reduced only slightly by the costs to install
worker exposure reduction measures. In addition, positive balance of trade
payments of about $13 million annually would be retained. With no effective
approved chemical or nonchamical alternatives to SOB currently available for
this use, the interim period would allow for the replacement of SDB with a
safer alternative.
However, until cancellation becomes affective, residues of EDB would
continue to occur in fumigated food commodities, and the U.S. public would be
at risk to unreasonable adverse affects resulting from dietary exposures to
these commodities. Persona in countries that import commodities treated in the
U.S. would be also potentially at risk to adverse health effects. The Agency
has determined that the lifetime probability (70 yr) of EDB-induced cancer to
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Jabln 30. Impacts of Regulatory Options on Post-Harvest
Ftaigatlon of Cltrua, Tropical Fruits, and Vegetables
EM Hi man Health Riaka
Rlaka of Subatitutea
Economic Tmoaota
O
in
Regulatory Ootfop Bvnoaure Route
1. Continued Inhalation
Registration Dietary
2.
3.
Classify for Same as Option 1
Restricted Use
and require
Amigatlon
center and
warehouse nodl-
flcatlon (see
Chapter 1 for list
of restrictions)
Option 12, plus Sana as Option 1
cancel after a
spec If lo tine
period.
Rlaka fluman/Envlronmental
Sea Tables Ifi Not Applicable
i. 20 for cancer
risks. See
discussion
in Chapter 5
for other
possible
risks.
Reduced Not Appllctble
fumigation
center and
warehouse
employee In-
halation risks;
dietary risks
unchanged.
Same risks as Not Applicable
for Option 12
except that
all risks
are eliminated
after selected
data whon cancellation
would become effective
Uaepa Consumers
None Nona
4500.00 per Hlntaal
each fumigation
chamber $13,000
per fumigation
center for
monitoring and
analytical
devices. I/
Option 12 Minimal
plus unknown
but probably
moderate coats
for instal-
lation of
gamina irradlatora
or other alternative
treatment methods
which become
available
Cunnenta
Unreasonable
dietary and
Inhalation
risks con-
tinue.
Unreasonable
dietary risks
continue.
Thla option
could allow
time for alter-
natives to be
developed and
registered.
1 Per chamber cost includes expenses for installation of a olosed EDB delivery (system, ventilation equipment and aafety devices (based on
personal couununlcatlon, J. Uiltealdea to J. Panetta 7/16/80).
-------
Table TO. Impaota of Regulatory Optiona for Poat-Rarveat
(Cent.) fumigation of Oltrua, Tropical Prulta, and Vegetables
EDB Iktman Health Rlaka
Regulatory Option
Exposure Route
maka
Rlaka of Bubstltytea
Ruaan/Envl ronmental
Economic Impaota
UsersConsunara Ccamenta
4. Immediately cancel uaa of EDB on crops consumed In the U.S., but allow continued uao on exported coanodltlea, with Option f 2 reatrlotlona imposed.
o
at
Inhalation
Poaalble Outccneat
A. Export market
to Japan la
retained
because IDE-
treated citrus
la acceptable
to Japan.
B. Export market Nona
to Japan
la lost
because EDB-
treated fruit
la unaccept-
able to Japan*
0. Export market None
la retained
through the
substitution
of Irradiation.
or other alternative
treatment method
Reduced
occupational
rlekj U.S.
public dietary
rlaka elimi-
nated. Rlaka
to Japaneae
unknown.
All EDB
rlaka elimi-
nated.
All EDB
rlaka elim-
inated.
Not applicable
Not applicable
B>e occupational
rlaka associated
with use of irra-
diation In the
U.S. are un-
lauvn, but likely
to be negllgltle.
$1.6M
(coat of
using gamma
Irradiation
not
Included).
Minimal
•AaBuaea Japan
will continue
to accept EDB
treated fruit.
$25M to Conauoer iaauoa citrus
uaara. prlcea previously
$16H loaa would exported will
In balance be lowered be abaored by
of trade. due to ex- U.S. market
ceaa supply through price
of oltrua reductions.
In the U.S.
Coat of None Japan la already
Implementing using irradatlon
and using for use on some
Irradiation. fooda; however, ra-
diation could not
be adopted inmodlately
In the U.S.
05
-------
Table ffi. Impacts of Regulatory Options for Poat-llarveat
(Cont.) Fuaigatlon of Citrus, Tropical Fruits, and Vegetables
pt)B
Blaka,
pf
Regulatory Potion
Exoosure Route
Riaka
Human/Environmental
5. Immediately cancel use on both domestic and export oropa.
Possible outcomest
Uaera
I
*-•
o
I
A. Export market None
to Japan Is
retained
because
Irradiation or
other alternative
treatment la
acceptable to Japan
B. Export market None
to Japan Is
lost because
Irradiation la
unacceptable to
Japan
All EDB rlaka
eliminated
All EDB rlska
eliminated
Occupational
risks of using
Irradiation
In the U.S. are
unknown, but
likely to be
negligible
Not Applicable
Same as "1C.
Tmr>anta
Consumers
Commenta
Minimal Japan and other countries
are already using irradia-
tion as a food preservation
technique. But irradiation could
not be implemented Immediately.
No protection would be offered
against the fruit fly until
implementation of irradatlon.
Irradiation
will likely
not be used.
Outcome results
eame as Option
H, Outcome B.
Consigner
prices
would be
lowered
due to
excess
supply of
cltrua in
the U.S.
-------
238
-4 -5
the average U.S. citizen is in the range of 10 for citrus and 10 for
tropical fruit. Thus, for example, if the Agency chose 70 years as a data when
cancellation of this use would become effective, one person in every 10,000
might incur cancer as a result of EDB residues in citrus, and one in every
100,000 from residues in tropical fruits. In addition to these risks,the
public would also be at risk to reproductive disorders and nutagenic effects.
The Agency considers these high levels of risk resulting from lifetime
exposure to be unacceptable, even in comparison with the considerable benefits
of SDB for this use. To allow the use of EDB to continue for seventy years
isunacceptable.
Option 5 —would eliminate the risks of EDB entirely, and for this reason
it has received serious consideration. Without appropriate alternative treat-
ment methods however, this option would totally eliminate the benefits of
ZDB for quarantine use.
There is one vital consideration which the Agency has extensively
investigated: whether gamma irradiation presents a viable alternative to ZDB
in the near future. As indicated previously, this method is effective and
approved for use in many countries, but has not yet been approved for use in
the U.S. The USDA APHIS has been researching this method for a decade, and
since 1974 has been attempting to receive approval of its petition to FDA for
use of gamma irradiation on mangoes and papays. USDA testing has also shown
good results for citrus.
Recently, the EPA. has met with the USDA and FDA to determine if USDA's
petition for the use of irradiation as'an alternative to SDB can be resolved.
Based on these discussions FDA has accelerated its review and it appears .that
FDA could approve the use of gamma irradiation within 18 to 24 months. Eased
on the Agency's contacts with manufacturers who market irradiation systems, it
appears that about 3 months would be required to install such systems (Welt,
1980a).
Based on this factor alone—that irradiation technology can be implemented
within about 24 =o 36 months—the Agency believes that Option 3 presents the
best solution. With this option the dietary risks to the U.S. population
would continue for 2 to 2 1/2 years. The estimated cancer risks are based on
a 70 year lifetime exposure, the cancer risks associated with this interia
periodqf 2 years would be about 2/70 of that risk, or about 10 for citrus
and 10 for tropical fruit. In light of the large benefits of EDB that
would continue for this period, the Agency finds that these lower risk levels
would be acceptable, but only for the 2 to 2 1/2 yr period. Any further
continuation of risk would be considered unreasonable. Regarding risks to
applicators and warehouse workers, the Agency finds that implementation of the
safaty measures previously described would significantly reduce the risks to
these persons without significantly effecting the economic benefits.
In conclusion, the Agency selects Option 3—phase-out of EDB after no more
than 2 1/2 years from now, and immediate implementation of applicator and
worker protection measures specified in Chapter IV or other measures to ensure
that the EDB air standard of 0.4 ppm is met. A reasonable date for the
cancellation to become effective -.vould be July 1, 1983. After that date, no
use of EDB will be allowed for post harvest commodity fumigation.
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239
D. S?CT FUMIGATION OF GRAIN MILLING MACHINES?
1. Summary of Risks and Benefits
In Chapters II and III, the Agency evaluated the risks and benefits
resulting from spot, fumigation of milling machinery and cereal handling
equipment:. This periodic treatment with EDB of critical spots in grain milling
machinery, ducts and conveyors is specifically timed to break the life cycle of
invading pests, thus preventing the tremendous increase in pests which could
result from the development of a second generation. The Agency has determined
that this use of EDB, amounting to 465,000 pounds per year, causes health risks
to the general public, mill workers, and fumigators. An investigation of
alternatives revealed that the only effective alternative for this use of EDB
is general space fumigation of the entire mill.
Recent studies which investigated the potential for residues of EDB to
contaminate wheat flour following spot treatment confirm that flour does absorb
residues and that they may persist for two weeks following treatment. The
amount of E3D which contaminates flour varies greatly and depends on numerous
factors including the length of time betveen spot treatment and wheat
processing, the concentration of SDB in incoming wheat, and the construction of
the flour mill. The Agency has determined that the average annual dietary
burden resulting from this use of EDB ranges from 0.7x10 to 2.77 x 10
mg/kg/yr. The Agency's Carcinogen Assessment Group used these residue levels
and estimated that the lifetime cancer risks to the U.S. public range from
approximately 10 to 10
These residue levels and the corresponding dietary cancer risks are.viewed
by the Agency as upper bound estimates of the actual cancer risks. The
estimated residue levels in bread include the assumption that all flour mills
use EDB as the method of treatment of milling equipment for pest prevention.
The number of mills using this process is unknown, as is the amount of wheat
flour processed annually through these mills. In the absence of this
information, the Agency has assumed that all mills use EDB.
The Agency has determined that spot treatment funigators and mill employees
are exposed to SDB vapors. These conclusions are based on findings from actual
EDS air concentrations measured during and after spot treatment. To estimate
the risks to fumigators of EDS-induced cancers, the Agency has considered both
typical exposures and, potential "worst-case exposures" (involving a fumigator
who moved or adjusted his face mask). The estimated lifetime risks range from
approximately 10 to 10 for applicators and 10 to 10 for mill
workers.
2DB, used as a spot funigant in flour mills, also presents potential
risksof mutagenic effects and reproductive disorders to the general public,
mill workers and fumigators. Although these risks have not been quantified,
they must also be considered along with the cancer risks 'in weighing the risks
and benefits of this general use of EDB.
The Agency estimates the economic benefits of spot fumigation to be in the
range of 4.6 to 7.5 million dollars annually. These benefits are based on the
assumption that, if this use of EDB were cancelled, the alternative would be
general space fumigation with methyl b.romide or aluminum phosphide. The costs
ara estimated to vary from 13 to 21 thousand dollars per year for individual
wheat and rye mills, and from 9 to 14 thousand dollars per year for dry corn
-109-
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240
mills. The resulting annual consumer impacts -would vary from an estimated 1,
to 2.8 cents per capita per year for four general space funigations, to 2.3
cents if five such fumigations are required.
aluminua
131°C),
The Agency has reviewed available data on the two substitute chemicals,
methyl bromide and phosphine, the active ingredient and degradation product of
jinum phosphide. Unlike 2DB, which is a liquid at room temperature (b.p.
tha alternatives (methyl bromide and phosphine, the active ingredient
of aluminum phosphide) are gases and would not be expected to leave significant
residues on treated surfaces and commodities. Both phosphine and methyl
bromide are acutely toxic, posing health hazards to unprotected applicators.
However, available toxicology information and consideration of the physical
properties of these chemicals lead the Agency to conclude that because of the
low expected residue level, neither would cause unreasonable adverse chronic
effects. Methyl bromide is known to cause mutations in some laboratory test
systems. Application and ventilation practices which protect applicators from
acute hazards should also provide significant protection to guard against the
potential mutagenic hazards of methyl bromide.
2. Risk/Benefit Analysis
Based on the above risk and benefit information, the Agency has determined
that the risks of adverse health effects exceed the economic benefits which
result from the use of SDB in spot fumigation of grain mills. Therefore,
unreasonable adverse effects to the public health exist and will continue to
exist unless the Agency adopts regulatory options to reduce them.
This determination has led the Agency to evaluate several regulatory
options which might reduce these risks. Table 31 presents the impact of each
option on the risks and benefits of spot fumigation.
Option 1, continued registration, would result in continued risks of
adverse health effects to the general population through dietary exposure, and
to applicators and flour mill employees through dermal and inhalation exposures.
Option 2, imposing certain use restrictions see details in Chapter IV)
would reduce applicator and general mill worker inhalation exposures to the
UIOSH recommended level of 0.4 ppm. Applicator dermal exposuras would also be
reduced. However, this option would not reduce the residues of EDB which
contaminate flour processed through grain milling equipment fumigated with SDB.
The intent of Option 3 is to achieve the same exposure reductions as Option
2, and also to lower the EDB-contamination of flour. By requiring that the
first batch of flour, produced after a mill has been fumigated, be discarded, a
portion of the EDB residues would be eliminated. However,the available
information is not adequate to determine the degree of reductionin residues
that might be achieved by this measure. Further, it would be difficult to
enforce such a restriction or to expect a high degree of voluntarycompliance.
Consequently, Option 2 would not likely result in a significantreduction of the
dietary residues of EDB from spot fumigation.
The impacts of Option 4, cancelling use after 5 years and restricting use
for the interim period, is the same as Option 3 until after the 5th year, at
which time the impacts would be the same as Option 5, i.e., cancellation. The
purpose of this option would be to allow tine for flour mills to upgrade their
facilities to use methyl bromide or aluminium phosphide.
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Table 31 Impacts of Regulatory Options for Spot Fumigation
EDB Itaan Health Risks
Rlek of Substitutes
Economic Impact
Coomenta
Regulatory Options Exposure Route
TT
2.
T~
4-
b.
Continued Dietary
Registration Inhalation
and Dermal
Classify for Same as Option 1
Restricted Use;
impose uae restrictions
listed in Part IV
Option 2 flame as Option 1
humfjn consumption of
flour allied during
the first several
hours
after H)B-treatnient
Cancel after £ years Same as Option 1
and impose Option 3
for the interim
Cancel Immediately No Exposures
Risks
fee Tables 16 and 20
for cancer risks and
discussion In
Part II for other
possible risks.
Dietary Risks
continue.
Reductions In
applicator and
non-applicator
risks.
Reduced applicator
and non-applicator
risks. Dietary
risks should be
reduced but the amount
reduction Is not known
Risks same
ea In Option 3 for
5 years; no risks
after 5 years.
All B)B risks
eliminated
ILnan Environmental
Hot Applicable
Hot Applicable
Not Applicable
of
After 5 years, the risks
of alternatives are the
same as in Option 5«
Aluminum phosphide JAP)
and methyl broulde (MB)
are acutely toxio
KB is a. suspect
•utagen
Users Consumers
None Nona
Respirators Nona
and clothing
cost about $100.
label and reentry
impacts are
negligible.
Coat of Negligible
discarding
flour woa
not analysed,
but is
probably minor.
None None
J5.1-I6.4H 1.6 to
par year 2.8 cents
for 293 per capita
wheat and
rye nllla;
$1.3M/yr.
for 93 corn
mils, total
max.inpuot •
57.? H/yr
Applicators would
probably comply
with restrictions.
Flour mills might
not comply with the
holding restriction
and enforcement
would be difficult.
During the 5 year
period, some mills
could modify their
facilities for use
of ice thy 1 bromide
or aluminum
-------
242
Immediate cancellation, Option 5, would force EDB users to switch
immediately to alternative funigants at a total increased treatment cost of
$7,700,000 per year for all 391 grain mills, or 2.8 cents per consuner. While
this is a "worst-case" estinate (because it assumes all mills now use EDB), the
potential cost of upgrading some mills to allow raaxiaan effectiveness from
space fumigation has not been included. In any event, this option would
eliminate the risks of EDB and '^ould result in use of apparently safer
substitute fumigants.
As the data presented in Table 31 demonstrate, any action short of
immediate cancellation will result in continued dietary risks. If the Agency
wera to classify EDB for restricted use, or amend the terms and conditions of
registration, some users nay continue to apply EDB rather than switch to
alternatives. Although occupational risks would be reduced, this option would
not result in a reduction in the risks to the general public resulting from
dietary exposure.
In conclusion, the Agency believes that the health risks of EDB are serious
and unacceptable when considered with the benefits, and will only be reduced
through immediate cancellation. Cancellation will not result in unreasonable
economic costs to grain mills or consumers. There are alternative chemical
fumigants for this use which the Agency believes will not cause the public and
properly protected applicators to be at risk to the range or magnitude of
serious adverse health effects that exist with use of EDB.
E. PRE-PLANT SOU. FUMIGATION
1. Summary of Risks and Benefits
The Agency has evaluated the hunan health risks and economic benefits of
the use of EDB as a pre-plant soil fumigant. The health risks of concern are
oncogenicity, mutagenicity and reproductive effects. These risks exist for
fumigation appl-icators and other individuals directly involved in application
operations, and might exist for the general public potantially exposed to EC3
residues in crops grown in firrigated soil.
The maximum hypothetical risks to humans resulting from potential dietary
exposure were estimated for the 16 soil-fumigated crops listed in Table 8 of
Chapter II. As discussed in Chapter II, no detectable residues of EDB have
been found at a level of detection of 0.001 ppn. Although the analytical
method used in these tests has not been completely validated, the Agency
assumes that residues will not exceed this level. To determine an upper-bound
lifetime probability of EDB-induced cancer resulting from dietary exposure, ths
Agency conservatively assuned that SDB residues are present at this level of
detection. Based on the assumption that a maximum of 0.001 ppm EDB is present
in each soil-funigated' crop, the maximum lifetime probability of EDB-inrtuced
cancer for the general public varies from approximately 10 to 10
However, because actual levels of EDB are probably below 0.001 ppn, the actual
cancer risks are also expected be lower than these maximum risk estimates. The
Agency has also concluded that if residues do occur, they also pose a potential
risk of genetic damage and reproductive disorders to man.
Soil fumigation applicators and those individuals involved in the transfer
of soil fumigants are likely to incur inhalation and dermal exposures during
SDB soil application and transfer. Soil funigation operators are exposed to
EDB ranging from 0,7 ng/yr for peach crops to between 303.3 and 522.4 mg/yr
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243
for pineapples. The Agency used these exposures to estimate that thg life time
risk of EDB-induced cancer to soil fucxigators is in the range of 10 to 10
As discussed in Chapter II, the Agency has also concluded that exposures
to SOB may result in hazard of genetic damage and reproductive problems to
exposed individuals.
In addition to the potential for residues occurring in crops, the Agency is
concerned that SDB might leach into groundwater as a result of current use
practices. Although no data are available on the leaching potential of EDB,
residues of the soil fumigant dibromochloropropane (DBCP), which has similar
use sites and use practices and chemical properties, have been found in ground
water. The Agency views this data gap as a significant issue which must be
resolved before final regulatory measures can be determined for this use. As a
result, the regulatory actions proposed for this use should be considered as
interim measures which will be finalized when adequate information is available
to evaluate this issue.
The Agency has evaluated the economic impact of cancelling soil funigation
with EDB and has determined that this use has substantial economic benefits.
All alternative treatment methods would be more expensive to farmers.
Depending on the crop treated, the total increased costs to farmers of using
alternative fumigants would vary from S3,500 for citrus to 33,000,000 for
vegetables. The total user impacts of cancelling all preplant soil funigation
uses would approach $21,000,000.
Numerous alternative pesticides are available for use as soil funigants in
place of EDB. The major alternatives in most cases are equally as efficacious
as EDB. The alternatives for most crops are DO, -Telone II and-Vorlex. For
pineapple uses, OBCP must be used in combination with DO or Telone. There are
both substantial health risks as well as a number of data gaps associated with
these substitutes, as shown in Table 26. A recent tICI study shows Telone to be
oncogenic. DD and Telone have been demonstrated to be cmtagenic in laboratory
tests-. DBCP is currently suspended for all uses except on pineapples due to
its oncogenic, rautagenic and reproductive hazards. The remaining alternatives
(Vorlex, Vemacur, Mocup, and Dasanit) have data gaps for most chronic effects
hazards.
2. Risk/Benefit Analysis
Based on the above risk and benefits information, the Agency has concluded
that there are significant health risks to soil fumigation applicators due to
exposure to EDB. The risks of cancer, mutagenic effects and reproductive
disorders to the occupationally exposed exceed the economic benefits for EDB
soil funigation. Therefore, it is necessary that the Agency consider
appropriate regulatory options to reduce these potential "unreasonable adverse
effects to the public health." The Agency considers the potential for EDB
residues to occur in water supplies and crops grown in funigated soils to be
data gaps which must be resolved. The regulatory measures which are developed
below are interim actions intended to reduce the health risks of EDB use as a
soil fumigant. When the data gaps are resolved, the Agency will reevaluate
this use to determine if additional regulatory measures are needed.
Table 32 identifies three possible regulatory options. They are in order
of increasing restriction: continued registration without restrictions,
continued registration with restrictions, and cancellation. Changes in the
risks and benefits of EDB expected to result from each option are also shown.
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418-574 0-83-17
-------
table 32 Impaota of Regulatory Optlona on Soil fumigation
H)B Human Health Rlaka Riak of Substitutes
Econottlo Impaota
Connenta
Regulatory Optlona
1.
2.
3-
Continued
Registration
Continue Registration,
but require Applicator
Use Restrictions, Set
Tolerances for EDB In
Fbod >opa, Require
Studies of Leaching
Potential and Pood
Residues
Immediate
Cancellation
Exposure Route
Inhalation and
Dermal for
applicators.
Potential
dietary and
drinking water
for the general
public.
Inhalation and
Dermal for
appl lea tore.
Potential
dietary and
drinking water.
for the general
public.
Rlaka
See Table IB
and 20 for
cancer rlaka
and discussion
in Chapter 5
for other
possible risks.
Dermal and
Inhalation
exposure risks
reduced
All EDB rlaka eliminated
Human/Envl ronmental
Not applicable
Hot applicable
DO and Telona are
oncogenlc and suspected
mutagena. Vorlex la
acutely tonic, but
haa no chronic effeota
data.
Users Consumers
None None
$175.00 llone
to
$600.00
per
applicator
$3,500 Nona
to
S3.6H,
depending
on use-site.
Unreasonable
applicator
health risks
continue.
Data gaps exist
for grounduater
contamination and
food residues.
Monitoring and
enforcement will
be necessary.
Monitoring data
needed for potential
of groundwuter
and food contamination.
EDB tolerances
must be established.
All substitutes
present potential
risks to human
health.
to
-------
245
Option 1, continued registration without restrictions, would result in
unreasonable adverse effects to applicators, as concluded above. Until more
definitive data are provided by registrants, the Agency also assumes that risks
to the public may result from potential exposure to EDB in food and/or drinking
water.
Option 2, continued registration with restrictions, would significantly
reduce risks to applicators, but would have no impact on the risk from
potential residues in food or drinking water. As a component of this option,
the Agency will require a study of the potential of EDB to contaminate food
crops grown in EDB-fumigated soils, and laboratory and field studies of the
leaching potential of EDB. The food residue study will investigate if residues
of EDB in crops grown in EDB-fumigated soils (at maximum application rates) do
not exceed the current limit of sensitivity of analytical methodology of .001
ppcu The studies on the leaching potential of EDB will be subject to the
Agency's review and evaluation prior to commencement.
Immediate cancellation, Option 3, would result in significant economic
costs to growers, but would eliminate all health risks from EDB. Losses to
growers would amount to almost 21 million dollars. In. addition, if this use
were cancelled, users would substitute other soil funigants which nay also pose
significant health hazards and have nunerous data gaps. If this use were
immediately cancelled, the Agency fcould have no assurance that the net risks to
public health would decrease.
The Agency selects Option 2 as the appropriate regulatory option for thrae
reasons: First, this option will establish risk reduction measures which lower
applicators-' risks at a reasonable cost. The specific use restrictions for the
protection of soil funigation applicators include all those measures specified
in Chapter IV: classifying EDB for restricted use by certified applicators
only; raquiring applicators to wear a NIOSH/MSHA-approved full face black
canister respirator during application; establishing a 24-hr post-application
period iuring which any person reentering the treated area must wear a
respirator; requiring EDB-resistant (butyl rubber) gloves ar.d boot covers
(butyle rubber, nitrile or polyethylene) be worn during mixing and loading of
EDB as well as during the maintenance of application equipment; and requiring
signs be posted on the treated site to notify readers of the treatment with ED3
and bearing further warning information. These restrictions will result in a
significant reduction in worker exposure, while maintaining the economic
benefits of SDB.
The second reason for selecting Option 2 is that the risks to public health
{pending resolution of the data gaps) which might result from the undetected
but possible exposure to EDB, are outweighed by the economic benefits. In
determining the risk of cancer due to consumption of SDB-funigated crops, the
"Agency assumed that a maximum of 0.001 ppm of EDB was present on each crop.
The ;astimate derived from this assumption is presuned to be a worst-case
estimate because 2DB has not been detected in analytical tests on such crops at
a level of detection of 0.001 ppm. To ensure that any EDB residues remain
acceptably low (i.e., < .001 ppm), the Agency proposes to establish a tolerance
for residues at the level of detection of EDB per se in or on food crops grown
in EDB Jvnigated soils.
The third reason for choosing Option 2 is that it will enable the Agency to
resolve the data gaps concerning the potential for SDB to contaminate food
crops and/or to leach into water supplies. Until these data are available, it
-115-
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246
is not possible to estimate quantitatively the risks for these health hazards
of EDB. The Agency therefore proposes to use Section 3(c)2(B) of FIFKA to
quickly obtain these additional data. When results of these studies are
available and have been evaluated, the Agency will reevaluate whether
additional regulatory actions are needed for this use.
Following the suspension of. DECP as la preplant for soybean nematode control
in 1979, several states have claimed there are no other registered pesticides
that are economical or effective against neraatodes. Based on the available
test results showing EDB to be as efficacious as DBCP, six states applied for
temporary permits (e.g., exemptions from FIFBA) to allow this use under section
18(c) of FIFKA. These exemptions were granted with the requirement that
numerous restrictions be implemented to reduce exposures to EDB and the
associated health risks to applicators. These exemptions were granted for the
period beginning April 24, 1980 and ending July 31, 1980. Table 3 lists these
restrictions, those applicants who applied for and received exemption, the area
and acreage to be covered, target pests, and the SOB products approved for each
use.
F. Minor Jses—Beehive Supers, Vault Fumigation. Termite Control, Bark
Beetle Control, and Japanese Beetle Control
1. Summary of Risks and Benefits
The Agency has examined the potential human health risks and the economic
benefits for four of the five known lower volune uses of EDB. A risk/benefit
evaluation of the fifth use—subterranean and drywood termite control—will be
deferred until a cluster analysis for all pesticides used for termite control
is conducted. The uses which are evaluated in this section include fmigation
of stored beehive supers and honeycombs (to control greater wax noth larvae),
vault fumigation of stored clothing and furniture (to control various pests),
treatment of felled logs (to control bark beetles), and treatment of APHIS
quarantined plants, soil and grass sod (to control Japanese beetles). The
health risks include cancer, genetic damage, and reproductive disorders.
As discussed in Chapter II, quantitative estimates of the risks are not
available for noat of these uses. However, as discussed below, an examina-
tion of the use practices for each of these uses reveals that applicators are
likely to be exposed to EDB during use and that they may be at risk to
unreasonable adverse effects.
Vault fumigation involves the pouring of EDB into a heating device, which
evaporates the EDB to penetrate items being treated. The formulation used in
vault fumigation is 5% EDB and the period for funigation is generally 16
hours. Thus, vault fuaigators can be exposed dermally during the pouring of
th^ formulation into dispensing containers and through inhalation during
pouring and when re-ntering the vaults. The Agency currently has no infor-
mation on the amount of EDB used annually for vault funigation, how many of
these facilities exist in the U.S., how many vault fumigation employees there
are in the U.S., or the levels of EDB to which vault funigation can be exposed.
No data exist on th<» exposures of beekeepers to EDB. However, use
practices for the fumigation of stored beehive supers suggest that beekeepers
nay be exposed both through inhalation and dernal contact but less frecuantly
than applicators for all other registered uses of EDB. Because this firrigation
procedure is an annual practice among certain beekeepers, exposures only occur
once a yeer when stored hives and supers are treated during the off season.
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247
Generally, one to two tablespoons of 33% SDB formulation are placed on
absorbent material which is set on stacked supers; the stack is then covered
with plastic sheeting for 24 hours. Both dermal contact: and inhalation of
vapor can occur during use. But the Agency has no estimate of the air levels
of EDB that could result from such use practices, nor of the frequency or
quantity of EDB dermal contact which could occur. However, the number of
beekeepers who use SDB could be large, because 20,000 Ibs. of EDB are estimated
to be used annually for funigation of supers and hives.
A separate but related issue for this use of EDB is the possibility that
EDB residues could occur in honey as a result of application to stored honey-
combs. As discussed in Chapter II, the Agency has no data on EDB in honey, but
views this as a very unlikely possibility. The Agency considers it as a data
gap which must be resolved to determine the total health risks which may exist
for this use.
No information exists on the EDB air levels to which individuals are
exposed during the treatment of felled logs. However, current use practices
suggest that both dermal contact and inhalation exposures will likely occur
during this use. Generally, a formulation of 23% EDB is applied to felled logs
in one of two ways: spraying to the point where runoff of Liquid occurs, or
spraying at a lower rate to stacks of wood which are subsequently covered under
a plastic sheet. Applicators thus may be exposed to EDB der-r.ally and through
inhalation of vapors during loading of sprayers as well as during actual use.
The use of plastic sheeting appears to offer some protection against inhalation
exposure both because it captures vapors and because of the reduced quantity of
formulation needed. Though the Agency has estimated that 20,000 Ibs. of EDB
were used in 1977, enough to treat an estimated 63,000 trees, there is no
information on the nunber of users or the frequency of use.
For funigation of quarantined plants, soil and grass sod. the Agency has no
information on applicator exposures, nuaber of applicators, frequency of us*» by
applicator, or the amount of EDB used for this site. This use is required by 7
CFR 201.48 (APHIS Japanese Beetle Domestic Quarantine Program). Current use
practices suggest that users may be exposed both through dermal contact and to
inhalation of SDB vapors. For each of these uses, EDB comprises either 2.5% or
20*% of the fontrulation (see Benefits Chapter). For all applications, the
formulation is mixed with water and applied in very low concentrations. During
the mixing of the formulation with water, users may contact SDB dermally or via
inhalation. During application of the diluted solution, exposure of users to
EDB will also occur. Because this solution contains very small quantities of
EDB, exposures are likely to be very Low.
The four minor uses of EDB each have economic benefits. For be-hivp
supers the benefits are considerable, amounting to nore than S1C million
annually. EDB is more effective than either of the alternatives, paradichloro-
benzene (PD3) and carbon dioxide. ?DB is generally much more practical to use
than CO.,, which requires elaborate monitoring equipment to ensure efficacy.
The substitution of PDB would result in increased treatment costs of about $2.7
million annually (approximately 5 cents per super) due to its higher cost and
to the additional treatments required. Because the alternatives are not as
effective as EDB, the quantity of domestic honey produced would be reduced by
an estimated 6 percent annually, resulting in a loss to beekeepers of 36.5
million. A production loss of this magnitude uould shift seine of the cost
impact to the consumer, but the extent of this impact cannot be estimated.
-117-
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248
Use of EDB on infested, felled trees to control the pine bark beetle in
western states, primarly benefits private land-owners. Although the extent of
EDB use does not appreciably affect the value of commercial timber harvests,
control of the pine bark beetle on residential lots may prevent tree mortality
losses of 51,500 to $3,000 per lot. The use of the alternative endosulfan
could actually reduce total costs by as much as 336,000 annually, in spite of
the fact that it may not be as effective as EDB. The other alternative,
lindane, could reduce treatment costs by up to ?16,000 annually. However,
because lindane is in RPAR and is recommended for cancellation for thus use, it
was not evaluated as a viable alternative.
The extent of the use of EDB in both vault fumigation of stored clothing
and furniture, and in the APHIS/USDA Japanese beetle quarantine program is
unknown. The economic benefits therefore, could not be quantified. A
registered acceptable alternative in the APHIS/USDA quarantine program is
methyl bromide. Four registered alternatives are available for vault fumi-
gation: a carbon tetrachloride/ethylene dichloride mixture, chloropicrin,
methyl brosiide, and sulfuryl fluoride. However, methyl bromide requires
extreme care in use, as described in Chapter III.
2. Risk/Benefit Analysis
The Agency has concluded that sufficient information exists to propose
cancelling the use of EDB to fumigate felled logs. The basis for this decision
lies in the fact that applicators are at risk to unreasonable adverse effects
of EDB, and because there are no known benefits for this use. Use of endo-
sulfan in place of EDB would result Ln a total reduction in treatment costs of
about $36,000 annually, even though it is not as effective as EDB. The Agency
concludes that the potential health risks to applicators through both dermal
contact and inhalation exposures to SDB outweigh these negative benefits.
In view of the lack of.risk and benefit information for the remaining three
uses, the Agency is unable to perform an adequate risk-benefit balancing
analysis. However, because applicators could potentially experience unreason-
able adverse effects of EDB, the Agency will require registrants to submit
certain data necessary to adequately evaluate the risks and benefits of each of
these lower uses. Because time will be needed to obtain these data, evaluate
it, and perform a thorough risk-benefit balancing, for the interim the Agency
has examined a number of actions designed to reduce applicator risks at a minor
cost. Summarized below by use are actions the Agency is proposing and data
which the Agency will require of registrants. These are organized on a use-by-
use basis for three of the four minor uses: fumigation of beehives and supers,
APHIS Japanese Beetle Control Program, and vault fumigation.
For fumigation of beehive supers and honeycombs, the Agency is proposing
the following interim label changes for such EDE products:
Certified Applicators — Fumigation may be conducted only by .or under the
supervision of a certified applicator.
Protective Clothing — EDB-resistant gloves (butyl rubber only), boo-.
covers and apron (made of butyl rubber, nitrile, or polyethylene) will be worn
at *11 times.
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249
Use Directions — Supers and honeycombs must be placed in a gas-tight
room or under a gas-tight covering such as a polyethylene tarpaulin held down
with sand-filled "snakes." All windows, doors and vents must sealed. All
persons not involved with the funigation must be vacated from the building.
Reentry Period — Following the treatment period, a full-face, black
canister respirator must be worn when reentering. All doors, windows and vents
must be opened at this time. Aeration for 24 hours or until EDB air levels are
less than 0.4 ppm measured by IS detector shall be required before reentry is
permitted. The label and warning signs (See Chapter IV) must contain this
information.
Limit fumigation to beehive supers that are clean and in storage. — 7o
avoid possible contamination of honey or honeycombs, the label will prohibit
treatments other than on clean supers or comb mounted in frames in storage.
This restriction is in accordance with current practice.
In addition to these label changes, the Agency is proposing to require the
following data from registrants:
1. ZDB air levels to which applicators are exposed during typical
conditions of use.
2. Number of users.
3. Residue studies to determine if EOB is detectable in honey from
fumigated supers and combs.
For vault storage, the Agency is proposing to require the following label
changes and use restrictions:
Protective Clothing — Require Che sane protective clothing listed for
beehive supers.
Certified Commercial Applicators — Vault funigation may be conducted only
by certified commercial applicators in commercial fumigation vaults.
Use Directions — Before ftanigation, all doors and leaks in the vault must
be sealed. All persons not involved with the funigation must be vacated from
the building.
Reentry Period — Following the treatment period, a full-face, black
canister raspirator aust be worn during reentry. All doors and vents in the
treatment area and connected buildings must be opened at this tims. Premises
must be aerated 24 hours or until EDB levels are less than 0.4 pan as measured
by-O detector before reentry is allowed. Posted warning signs {See Chapter
IV) must bear this information.
In addition to these label changes, this Agency proposes to require the
following information from registrants:
1. .'tonitoring studies of the SDS air levels to vhich applicators may be
exposed, both during pouring .EDB into dispensing containers and also during
reentry into the vault after fumigation.
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250
2. Survey data on the number of vault funigation operations using EDB and
the nvraber of applicators involved in this practice; and
3. Data on the amount of EDB applied annually for this use.
For the APHIS Japanese Seetle Control Program, the Agency is proposing to
require the following label restrictions and revisions in the APHIS Manual:
Grass sod — Treated sod must be covered with a heavy plastic or tarp
during the treatnent period to ensure an efficacious treatment and to minimize
air exposures. The tarp must be aired before re-use.
3areroot Plants — The proper method for disposing of the used EDB-vater
mixture must be specified.
Sailed or Containerized Plants — The "enclosed place" into which plants
are placed after treatment nust be posted with signs indicating the minimal
reentry information described previously. Proper disposal methods must be
described.
Potting and Bench Soil — Soil must be covered with plastic or heavy tarp
for duration of the treatment period.
Sees and Other Uses — Soil must be covered with plastic or heavy :ar? for
duration of the treatment period.
For All Above Uses — The APHIS Manual states for balled or containerised
plants that treatment is approved only when beetle grubs (larvae and pupae) are
present. This requirement must be imposed for all regulated articles to avoid
unnecessary applications.
For this use, the Agency is proposing to require the following information:
1. Monitoring studies of the air " evels to which applicators are exposed
during mixing and during use.
2. Data on the amount of EDB used annually, the nunber of applicators and
the frequency of use.
In addition to these actions, the Agency is proposing to require certain
interim measures for the use of EDB in the control of termitas. As discussed
earlier, the Agency is proposing to defer a risk/benefit balancing decision for
this use and will include it in a cluster analysis of all pesticides used for
temite control. In the interim, however, the Agency recognizes that both
applicators and persons in the immediate treatment area can be axposed and are
therefore at risk to unreasonable adverse affects. To reduce exposures of
applicators and non-involved persons to EDB, the Agency proposes the following
use restrictions be included on the label:
Certified Commerieal Applicators — Fumigation may be conducted only by a
certified commercial applicator wearing a full-face, black canister respirator;
Protective Clothing — EDB-rssistant gloves, boot covers and apron will be
required at all tiaes;
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251
Use Directions for Drywood Tarnites — Persons not involved with the
fumigation must leave the premises. Holes of size and spacing specified by the
registrant must be drilled and the recommended dosage of EDB inj ected into
these holes using a calibrated syringe or like device.
Use Directions for Subterranean Termites — Persons not involved with ths
fuaigation must leave the premises before fumigation and subsaquent aeration.
Use is not permitted under slabs which contain air ducts, electrical conduits,
or the like. Recommended dosage must be injected through holes drilled in
concrete slabs which support infested structures. All holes must be plugged
temporarily to prevent the escape of EDB during treatment, and must be sealed
permanently immediately after treatment* The label must stats these
requirements.
Reentry Period — During and after funigation all doors, windows -ind
vents in the treatment area and connected buildings would be opened. Premises
must be aerated 24 hours or until EDB air levels are below 0.4 ppra before
reentry is permitted. The label and posted warning signs must contain this
information.
In addition, the Agency is proposing to require registrants to provide data
which would be needed in the cluster analysis. These data are:
1. Air concentration of EDS to which applicators are exposed, their
annual time spent using SDB, the number of applicators using EDB in
the U.S., and the amount of formulation sold annually; and
2. Air monitoring studies which investigate the potential SDB air levels
to which persons not involved can be exposed. These -would include
indoor places at or near the site(s) of application.
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252
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Lancet, 17 December 1977
Williams, M. 1980a. Memorandun to Edwin L. Johnson. Re: Request to contact FDA
regarding- the use of gaoma radiation. 15 January 1980
Williams, M. 198Ob. Memorandum to Edwin L. Johnson. Re: FDA requirements for
approval of gamoa radiation for use on citrus. 28 Fedruary 1980
Wit, S.L., A.F.H. Besemer, a .A. Das, W. Goedkoop, F.E. Loosjes, and E.K.
Mepellink. 1969. Results of an Investigation on the Regression of Three
Fumigants (Carbon Tetrachloride, Sthylene Dibromide, and Ethylene
Dichloride) in Wheat During Processing to' Bread. Report from the Director
General of the National Institute of Public Health to the Inspector General
of Public Health in charge of Foodstuff Division, Bilthoven, Netherlands.
April 1969, 21 pp
Wit, S.L., A.F.U. Besemer, H.A. Das, W. Goedkoop, F.E. Loosjes and E.K.
Mepellink. 1977. Determination of Residues of Ethylene Dibromide in Bread
and Flour, Final Report. Litton Bionetics, Inc. Project No. 20880
Wit, S.L., A.F.U. Besemer/ H.A. Das, W. Goedkoop, F.E. Loosjes and E.K.
Mepelink. 1978* Determination of Residues of Ethylene Dibromide in Wheat
and Wheat Products, Final Report. Litton Bionetics, Inc. Project No. 20927
Wong} L.C.K., et al. 1979. Study of Carcinogenicity and Tbxicity of Inhaled
1,2-QLbromomethane in Rats Treated with Disulfiram. Midwest Research
Institute Final Report, NIOSH contract No. 210-76-0131. 8 February 1979.
100 pp
Wong, 0. (1978). A Retrospective Study of Inferred Fertility of Married Man
Occupationally Exposed to Sthylene Dibromide (EDB). Report from Equitable
Environmental Health, Inc., Rockville, Maryland to Ethyl Corporation, Baton
Rouge. In: Rebuttal Docunent #48(30000/25}
-------
261
Worthington, John. 1979. Memorandum to Anthony Inglis, SPRD, commenting on
California food crop a thy lane dibromide residues. Residue Chemistry Branch,
Hazard Evaluation Division, U.S. Environmental Protection Agency. 19 July
1979, 2 pp
Worthington, John. 1978. Final Dietary Exposure Analysis for Ethylene
Dibromide Resulting From Residues in Funigated Crops and Ebod Commodities.
Residue Chemistry Branch, Hazard Evaluation Division, 29 December 1978. EPA
Zygadlo, Linda. 1978. Memorandum to John Worthington, HED, giving percentages
of crops treated with ethylane dibromide. Economics Analysis Branch,
Benefits and Field Studies Division, U.S. Environnental Protection Agency.
7 December 1978, 2 pp
-------
262
APPENDIX 1
RESPONSES RECEIVED REBUTTING HEALTH TRIGGERS
Rebuttal No. Source Data of Submission -
3C
7
13
14
15
1SA
1SB
16
22
22A
223
22C
22D
26
31
32
33
47
47A
48
64
Great Lakes Chemical Corporation
Chevron Chemical Company
University of Idaho Cooperative
Extension Service
Department of Citrus, State of Florida
Millers National Federation
Millers National Federation
American Corn Millers Federation
Colorado State Uhiversity
Ferguson Fumigant Inc.
Ferguson Fuaigant Inc.
Ferguson Fumigant Inc.
Ferguson Fvnigant Inc.
Ferguson Fumigant Inc.
Pineapple Growers Association of
Hawaii, Honolulu
Florida Agricultural Research Institute
Florida Farm Bureau
Department of Agriculture
Honolulu, Hawaii
Douglas Chemical Company
Douglas Chemical Company
Ethyl Corporation
Vulcan Materials Company,
01/23/78
01/16/78
01/19/78
01/20/78
01/24/78
04/07/78
04/07/78
01/26/78
01/31/78
02/01/78
04/04/78
04/13/78
06/01/78
12/12/77
01/31/78
01/31/78
01/31/78
02/09/78
04/13/78
01/31/78
04/03/78
2/
Chemical Division
65 Florida Citrus Commission 04/03/78
-------
263
56 Environmental Defense Fnnd 04/04/78-04/03/78
73 Dow Chemical 04/26/78
79 Cooperative Extension, University of 04/1 1/78
California
J/ Dates given are the dates OFP's Federal Register Section received the
submission.
2/ Three additional addenda were submitted on this rebuttal.
-------
APPENDIX 2
WOM FOOD IRRADIATION NEWSLETTER
OCTOBER 79, IAEA
LIST OF CLEARANCES
GENERAL
COUNTRY
(Organisation)
BULGARIA
SURVEY Or IRRADIATED rOOD PRODUCTS
(Grouped according to country)
PRODUCT
pota,toea *)
potato** *)
onlona *)
garlic *)
grain »)
dry food concentrate* •)
dried fruit* *)
CLEATBD rOR HUHAN CONSUMPTION IN DirrBRENT COUNTRIES
Auguat 1979
PURPOSE Or TYPE AND SOURCE DOSE
IRRADIATION Or RADIATION (k Gy)
aprout Inhibition +
aprout Inhibition + O.I
aprout Inhibition + 0.1
aprout Inhibition + 0.1
aprout Inhibition + 0.3
Inaact dlalnfeatatlon -1- 1
Insect dlalnfeatatlon -t 1
DATE Or A
30 April
30 April
30 April
30 April
30 April
30 April
PPROVA1
1971
1972
1972
1972
1972
1972
1972
freah fruit* ' (toaatoea,
peachea, apricot, cherry,
raapberry, grapea)
to
radurlcatton
2.5
30 April 1972
-------
COUNTRY PRODUCT
(Organization)
CANADA potatoes
onions
wheat, flour, whoje wheat
flour
MM)
poultry
cod & haddock fillets
l\ IIMl
CHILE potatoes '
CZECHOSLOVAKIA potatoes "'
»\
onions
• »
Mushrooms
PURPOSE Of TYPE AND SOURCE DOSE DATE OF APPROVAL
IRRADIATION OF RADIATION (k Gy)
60p 137- elec-
L0 CS trons
sprout Inhibition *
sprout Inhibition *
Insect dlslnfestatlon *
radlcldatlon
(Sal«onella) *
radurlzatlon +
sprout Inhibition +
sprout Inhibition +
sprout Inhibition +
growth Inhibition t
O.I wax 9 Novonber
0.15 nax H June
0.15 Max 25 March
0.75 «ax 25 February
7 max 20 June
1.5 Max 2 October
31 October
O.I Max 26 November
0.06 max 26 November
2 Max 26 November
I960
1963
1965
1969
1973
1973
1974
1976
1976
1976
fj\
DENMARK
potatoes
sprout
10 HaV
0.15 max
27 February 1970
-------
COUNTRY PRODUCT
(Organization)
FRANCE potatoes <">)
• it
onions
••I
garlic '
••»
shallot '
•| •••!
FRG deep-frozen Mais '
• t
potatoes
• •••i
HUNGARY potatoes '
potatoes
•••ii
potatoes
• •••I
onions
• ••it
onions
onions
strawberries
PURPOSE OF
IRRADIATION
sprout Inhibition
sprout Inhibition
sprout Inhibition
sprout Inhibition
radappert 1 zat Ion
sprout Inhibition
sprout Inhibition
sprout Inhibition
sprout Inhibition
sprout Inhibition
sprout Inhibition
sprout Inhibition
radurlzatlon
TYPE AND SOURCE DOSE
OF RADIATION (k Cy)
60co I37CS elac-
* 0.075 - 0.13
+ * 0.075 - O.J5
* * 0.075 - 0.15
* + 0.075 - 0.13
+ 25 -45
t O.IS MX
* O.I
* O.|5 MX
+ 0.15 MX
t
+ 0.06
* 0.06
*
DATE OF APPROVAL
a November 1972
9 Au
-------
COUNTRY PRODUCT
(Organization)
»\
IUNGAHY mixed spices (blackpepper,
(cont'd.) cumin, paprika, dried garllci
for use In sausages)
nixed dry Ingredients for
canned hashed maat ')
(wheat flour. Na caselnate.
onions and garlic powder,
paprika)
ISRAEL potatoes
onions
ITALY potatoes
onions
garlic
PURPOSE OF TYPE AND SOURCE DOSE DATE Of APPROVAL
IRRADIATION OF RADIATION (k Gy)
M- '"<» S=
radlctdatlon •»
radiation
decontamination t
sprout Inhibition *
sprout Inhibition 4
sprout Inhibition t
sprout Inhibition t
sprout Inhibition +
5 2 Apr II
5 20 November
0.15 max 5 July
O.I MX 25 July
0.075 - 0.15 DUX 30 August
0.075 - O.IS 30 August
0.075 - 0.15 30 August
1974
1976
1967
I9btt
1973
1973
1973
1
JAPAN
potatoes
sprout Inhibition
Q.I5 max
30 August 1972
-------
COUNTRY PRODUCT
(Organization)
it
NETHERLANDS asparagus
cocoabeans
• •«*)
strawberries
jnushrooas
nit
deep-frozen reals
potatoes
peeled potatoes
shrimps
• nit
shrimps
i)
onions
onions
PURPOSE OF TYPE AND SOURCE DOSE
IRRADIATION OF RADIATION (k Gy)
60 137 elac-
00 Cs trons
radurlzatlon *
Insect dlslnf estatlon •»
radurlzatlon *
growth Inhibition *
radappertlzatlon +
sprout Inhibition *
rttdurlzat Ion *
radurlzatlon +
radurlzatlon +
sprout Inhibition +
sprout Inhibition t
2 max
4 HeV 0.7 max
4 HaV 2.5 max
4 HaV 2.5 max
25 nln
4 HeV 0.15 max
0.5
4 HeV 0.5 - 1
1
0.15 max
0.05 max
DATE OF APPROVAL
7 Hay
7 Hay
7 Hay
23 October
27 November
23 Harch
12 Hay
13 November
15 June
5 February
9 June
1969
1969
1969
1969
to
as
1969 00
1970
1976
1970
1976
1971
1975
poultry, eviscerated
(In plastic bags)
raiiurlzatlon
max
31 Uocomber 1971
-------
COUNTRY PRODUCT
(Organization)
NETHERLANDS chicken
(cont'd.)
fresh, tinned & liquid
iiti
foostuffc
spices & condiments
1*1
spices
spices
*•)
spices
vegetable f 1 1 ling
powdered bat term! x
• «i«i
endive
PURPOSE Of TYPE AND SOURCE DOSE
IRRADIATION OF RADIATION (k Cy)
60f 137 elec-
00 Cs trons
radurliatlon.
radlcldatlon +
radappertfzatlon +
radlcldatlon t
radlcldatlon +
radlcldatlon *
radlcldatlon t
radlcldatlon +
radlcldatlon +
radurlzatlon *
3 max
25 nln
4 HaV a - 10
4 HeV 10
3 MaV 10
10
0.75
1.5
1
DATt Of APPROVAL
10 Hoy
8 March
13 Suptomber
4 October
26 June
4 April
4 October
4 October
14 January
1976
1972
1971 |
1974
1975
I97U
1974
1974
1975
fresh vegetables
(prepared, cut,
soupgreons)
radurUatlon
1977
-------
COUNTRY PRODUCT
(Organization)
NETHERLANDS fl 1 lets of haddock, „„,.
(conl'd.) coal-fish, whiting '
• •«i\
fillets of cod 1 plaice '
**)
frozen frog legs
rice and ground rlca
• it
products
PHILIPPINES potatoes *"'
SOUTH AFRICA potatoes
onions
garlic
chicken
papaya
PURPOSE OF
IRRADIATION
radurlzatlon
radurlzatlon
radlcldatlon
dlslnfestatfon
sprout Inhibition
sprout Inhibition
delayed greening
sprout Inhibition
sprout Inhibition
radurlzatlon
radurlzatlon
TYPE AND SOURCE
OF RADIATION
+
+
+
+
t
+
*
+
t
+
DOSE
(kGy)
1
1
5
1
0.15 nax
0.12 - 0.24
0.05 - 0.15
O.I - 0.20
2-7
0.5 - 1.5
DATE OF APPROVAL
6 September 1976
7 September 1976
25 September 1976
tc
13 March 1979 o
13 September 1972
19 January 1977
25 August 1978
25 August I97U
25 Auyust I97U
25 August I97U
-------
COUNTRY
(Organization)
SOUTH AFRICA
(cont'd.)
SPAIN
THAILAND
UNION OF SOVIET
SOCIALIST REPUBLICS
PRODUCT
pango
strawberries
dried bananas
avocados
potatoes
onions
onions
potatoes
potatoes
grain
fresh fruits A vegetables '
PURPOSE Of TYPE AND SOURCE DOSE DATE OF APPROVAL
IRftttlATION OF RADIATION (k Gy)
radurlzatlon *
radurlzatloh *
Insect dlslnfestatlon +
delayed ripening i
sprout Inhibition *
sprout Inhibition *
sprout Inhibition *
sprout Inhibition +
sprout Inhibition
Insect dlslnfo&tatlon +
radurUatioo t
0.5-1.5 25 Auyust
1-4 25 Auyust
0.5 max 28 July
O.I MX 28 July
0.05 - 0.15 4 November
0.06 Max
O.I wax 20 March
O.I 14 March
1 HeV 0.3 17 July
0.3
2-4 j| July
1978
1970
1977
1977
1969
1971
,973
1958
1973
1959
1964
-------
COUNTRY PRODUCT PURPOSE OF TYPE AND SOURCE
(Organization) IRRADIATION OF RADIATION
60_ |37_ el
Co Cs .
UNION OF SOVIET semi-prepared raw beef,
SOCIALIST REPUBLICS pork & rabbit products
(cont'd.) (In plastic bags) ") radurlzatlon t
dried fruits Insect dlslnf estatlon t
dry food concentrates Insect dlslnf«statlon t
(buckwheat aush, gruel
rice pudding)
poultry, eviscerated radurlzatlon +
(In plastic bags) •)
culinary prepared naat radurlzatlon +
products (tried mat,
entrecote) ,.
(In plastic bogs)
onions sprout Inhibition •*•
onions sprout Inhibition t
DOSE OATH OF APPROVAL
(kGy)
ec-
ons
6 - (t II July 1964
1 15 February 1966
0.7 6 June (966
6 4 July 1966
fi 1 February I9b7
0.06 25 February 1967
0.06 (7 July 1973
-------
COUNTRY
(Organization)
PRODUCT
PuflPOSE Of
IRRADIATION
TYPE AND SOURCE
OF RADIATION
60,
Co '""Cs
trons
DOSE
(k Gy)
DATE Of APPROVAL
UNITED KINGDOM
any food for consumption
by patients who require
a sterile diet as an
essential factor In their
treatment
rodappert Izat Ion
I December 1969
UNITED STATES
Of AMERICA
wheat and wheat flour
(changed on 4 March 1966
from wheat and wheat
product)
white potatoes
Insect dlslnfestatlon +
sprout Inhibition
5 MaV
0.2 - 0.5
0.2 - 0.5
0.2 - 0.5
0.05 - O.I
0.05 - O.I
0.05 - 0.15
-3
CO
21 Au.just 1963
2 October 1964
26 February 1966
30 June 1964
2 October 1964
I November 1965
URUGUAY
potatoes
sprout Inhibition
23 June
1970
-------
COUNTRY
(Organization)
WORLD HEALTH
ORGANIZATION
(FAO/IAEA/HM5
Export Conn in aa)
PRODUCT
potatoes
potatoes
onions
papaya
strawberries
wheat A ground wheat
products
wheat 4 ground wheat
products
rice
chjcken
cod & red Msh *'
PURPOSE OF TYPE AND SOURCE DOSE
IRRADIATION Of RADIATION (k Gy)
60Co I37CS ?
-------
APPENDIX II
COMMENTS RECEIVED IN RESPONSE TO FD 2/3
Conment No. Source
1 W.B. McCloud & Co.
2 Millers National Federation
3 County of San Diego
Department of Agriculture
4 Florida State Beekeepers Assoc.
5 State of Hawaii
6 Anheuser-Busch, Inc.
7 The American Beekeeping Federation
8 American Corn Millers Federation
9 Butts County Mosquito
Abatement District
10 California Farm Bureau Federation
11 LeBost, Mr. & Mrs, Deerfield
12 Jackson County Farm Bureau
13 Boettcher Supply, Inc.
13A Reiling, Mr. Gregg
14 Chio Dept. of Agriculture
15 Colorado State Forest Service
Colorado State University
ISA Colorado State Forest Service
Colorado State University
16 University of Nebraska-Lincoln
Cooperative-extension Service
17 State of North Carolina
Dept. of Agriculture
18 Crawford, Mr. Johnny L.
ISA University of Georgia
College cf Agriculture,
Cooperative Extension Service
275
-------
APPENDIX IH
FEDERAL INSECTICIDE, FUNGICIDE, AND RODENTICIDE ACT (FIFRA)
SCIENTIFIC ADVISORY PANEL
Review of Preliminary Notice of
Determination Concluding the Rebuttable
Presumption Against Registration (RPAR)
of Pesticide Products Containing
Ethylene Dibromide (EDB)
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific
Advisory Panel has completed review of plans by the Environmental Protection
Agency (EPA) for initiation of regulatory action on pesticide products
containing ethylene dibromide (EDB) under the provisions of Section 6(b)(2)
of FIFRA as amended. The review was completed in an open meeting held in
Arlington, Virginia, on March 25-26, 1981.
Maximum public participation was encouraged for the review. Public notice
of the meeting was published in the Federal Register on February 25, 1981.
In addition, telephone calls were received from and mailings sent to the
general public who had previously expressed an interest in activities of
the Panel. Oral, and in most cases, written statements were received from
the technical staff of EPA's Office of Pesticide Programs, and from repre-
sentatives of the U.S. Department of Agriculture; the State of Florida,
Department of Citrus; Ethyl Corporation; the University of California;
the Hawaii papaya industry; Dow Chemical Corporation; National Pest Control
Association; Hopes Consulting Company; National Association of Wheat Growers;
Emergent Technologies, Incorporated; and Radiation Dynamics, Incorporated.
The excellent briefings by the staff of OPP's special Pesticide Review
Division (SPRD) were of great value to the Panel. The Panel wishes to
express its appreciation to SFRD for having prepared a Position Document
2/3 on EDB of very high quality. Also, the Panel would like to thank
Dr. Carol Sakai, Reproductive Effects Assessment Group, EPA, for an
outstanding scientific briefing on the reproductive effects of EDB.
In consideration of all matters brought out during the meeting and careful
review of all documents presented by the Agency and other parties, the
Panel unanimously submits the following report:
277
-------
REPORT OF SCIENTIFIC ADVISORY PANEL RECOMMENDATIONS
The Agency requested the Panel to focus Its attention upon these
issues:
1. The data requirements (ground water, food residues for pre-plant,
exposures and survey data for minor uses applicator)
2. The acceptability of risks during the phase ouc of citrus
3. The similarities of this pesticide to dibromochloropropane (DBCP)
o use sites
o health risks
o chemical structure
4. The acceptability of alternatives relative to the toxic hazards
of EDB expecially for grain and citrus.
The Panel's response to each of the above issues is as follows:
1. The data requirements (ground water, food residues for pre-plant,
exposures and survey data for minor uses applicator)
The Panel expresses considerable concern over the potential human
hazard as a result .of the spot fumigation in flour mills use of Ethylene
Dibroeide (EDB) and recommends that EPA require a thorough and critical study
of EDB residues in grain, as veil as obtain residue data in bread and other
bakery products.
The Panel also indicates its concern over the possible appearance
of EDB in ground water, and urges that ground water be monitored closely
in high use areas.
The Panel recommends that a reproductive study on rodents be
performed with critical structural and functional analysis of endocrine,
reproductive and fetal tissues.
Finally, the Panel recommends that EPA monitor high risk workers
in the grain, citrus and minor use areas, both during and following exposure.
279
-------
280
2. The acceptability of risks during the phase out of citrus
The Panel differs with the Agency's position that EDB use on
citnifl should be phased out by July 1983. Rather, the Panel proposes
that this use be retained in a similar manner as several other uses which
the Agency is proposing be allowed, but with certain restrictions imposed,
including pre-plant fumigation of soil, stored beehive fumigation, stored
furniture and clothing, and nursery stock.. The reason for this is that the
Panel finds it difficult to evaluate whether it is feasible for the citrus
industry to move to irradiation as an alternative to EDB control of fruit
flies. Therefore, the Panel recommends reevaluation of the risks and
benefits of irradiation as an alternative for EDB as soon as possible.
In the meantime, the Panel recommends the use of additional
protective measures to reduce worker exposure. It appears to the Panel
that substantial improvements can be made in EDB application technology,
and that such improvements will reduce both the number of workers exposed
and the severity of the exposure.
3. The similarities of EDB to" DBCP with regard to -hdmical structure,
use sites and health risks
The Panel finds that EDB has certain structural qualities, uses
and adverse effects which resemble those of DBCP. However, extrapolation
from one compound to another entails the same kind of uncertainties as
does extrapolation in testing from one species to another. Therefore,
the Panel recommends that the data be obtained on EDB directly rather than
on the basis of extrapolation from other compounds.
4. The acceptability of alternatives relative to the toxic hazards
of EDB especially for grain and citrus
The Panel finds that alternatives to EDB appear to be available
in several areas, e.g., fumigation of stored grain, termite control, bark
beetle control and other sdnor uses. Alternatives for soil fumigation and
citrus are not well developed and clearly demonstrated to be efficient,
practical, and feasible from a cost standpoint.
The Panel's response to the issues listed by EPA as regards EDB is
based on the following evaluation of the available data base for this
agent:
1. EDB is a carcinogen for multiple animal species of both sexes
producing oncogenic effects in several tissues following exposure by at
least two routes of administration.
-------
281
2. EDB is a potent mutagen -producing point (gene) mutation, chromosomal
aberration and primary DKA damage in multiple test systems involving both
prokaryotic and eukaryotic systems (including mammals).
3. EDB has been demonstrated to produce adverse reproductive effects
in several species. None of these studies definitively demonstrates a
no observed effect level (NOEL). As indicated above, the Panel recommends
that a reproduction study in rodents be required to characterize the threshold
dosage level for EDB effects on fertility, mating, gestation, etc.
The Panel notes that it will be very difficult to conduct epidemiolo-
gical studies that will enable EPA to ignore the results of animal studies.
Such epidenjiological studies which have been conducted thus far do not
provide convincing evidence that animal tests do not accurately predict
potential human hazards in the area of oncogenicity and reproductive
effects. Therefore, it is necessary to regulate on the basis of animal
studies alone.
The Panel wishes to make a clear distinction between the apparent
hazards of citrus and grain fumigation insofar as human dietary factors
are concerned, and thus does not concur with the Agency's proposal to
cancel the use of EDB on citrus. As regards stored grain fumigation and
spot fumigation of grain milling machinery, the Panel wishes to express
its great concern over the possible presence of EDB residues in finished
bakery products. The evidence is far from solid, but because of the extremely
large population potentially at risk, the problem demands resolution.
Therefore, the Panel concurs with the EPA proposal to cancel stored grain
fumigation and spot fumigation of grain milling machinery uses until such
time as convincing evidence exists that such uses present little or no
hazard to consumers of bakery products.
FOR THE CHAIRMAN:
Certified as an accurate report of findings:
PMlip HGray,
Acting Executive Sretary
FIFRA Scientific Advisory Panel
Date: April 22, 1981
-------
282
DEPARTMENT CF AGRICULTURE
orncc or TMC SCCSC-»B>
WASHINGTON. 0 C. 2025O
Ipril 6 3981
Honorable Walter C. Barber, Jr.
Acting Administrator
U. S. Environmental Protection Agency
Washington, D. C. 20460
Dear Mr. Barber:
This is the U. S~ Department of Agriculture's response to the U. S.
Environmental Protection Agency's Preliminary Notice of Determination
concluding the Rebuttable Presumption Against Registration (RPAR) of
pesticide products containing ethylene dibromide (EDB).
We concur in the decision to continue use of EDB for soil fumigation and
to the postponement of a decision on several other uses pending receipt
of additional data. We do not concur that EDB should be cancelled, for
fumigation of felled logs, or for quarantine purposes. It is our con-
clusion that there is insufficient information to adequately Indicate
that gamma irradiation 1s or will be a feasible substitute for EDB
quarantine fumigation on a broad scale basis by July 1, 1983. We
believe that, in light of new information on use and the lack of viable
alternatives the actions on these uses of EDB should be Devaluated.
We agree that, more data are needed on residue levels of EDB on treated
and processed commodities as well as more data on the effectiveness of
worker and applicator protection techniques associated with EDB. We
will cooperate with: EPA and industry to provide additional data as
necessary.
Our specific comments are contained in the enclosure which is an Inte-
gral part of this response. In view of the complex issues Involved, the
additional time that your agency granted for review of this document was
very beneficial and is appreciated.
Sincerely,
Secretary
Enclosures
-------
SECRETARY OF AGRICULTURE'S
SPECIFIC COMMENTS TO
EDS NOTICE OF DETERMINATION PO 2/3
I. Preplant Soil Funrigatlon
USDA is willing; to provide input and assistance to EPA and Industry to
develop acceptable experimental design and/or additional data to resolve
concerns associated with potential residues on crops grown 1n soil that
has been treated, with EDB.
II, Fumigation of Stored Grain
More recent data has been developed from an interagency study in SEA:AR,
ASCS, and FGIS, which 1s now in progress to measure the level of insect
and fungal activity in farm stored grains This study consists of grain
samples and storage information from about 4,000 bins of wheat,. 3,000
bins of corn, and 1,000 bins of oat stored on farms in 20 States.
Storage information- obtained in this study includes a record of measures
taken by the producer to maintain the quality of the grain during storage.
Preliminary analysis of these data indicated that less than 3 percent of
the wheat bins and less than 1 percent of the corn and oat bins were
fumigated during the 1-4 year on-farm storage. Fumigation occurred most
often during the second year of storage, generally in the late summer or
early falU Fumigant materials identified as being used in the farm
treatment included aluminum phosphide» chloropicrin, and a liquid fumi-
gant mixture composed entirely of carbon tetrachloride (CC1.) and carbon
disulphide (CS-) (80:20) or these two used in conjunction with 1.2 to 5
percent ethylene dibromide.
An Interim analysis of EDB use in on-farm storage may be estimated from
the study now. in progress whicrr shows the following percentages of grain
being treated with EDB.
Grain in
Storage
Wheat
Com
Oats
Barley
Sorghum
Amount In Storage
(1,000 bushels)
972,054
2,494,504
388,625
240,442
39,708
% Treated
2.0
0.5
0.25
0.25
0.25
Lbs. EDB Used
52,492
4,489
349
108
54
The results of this study are expected to be tabulated in computer
Storage by May 1, 1981.
EDB liquid fumigant formulations are labelled for use in both on-farm
and commercial elevator storage. In actual practice EDB fumigation of
stored grain is concentrated in on-farm storage. Liquid formulations
were developed specifically for this purpose. EDB is included in liquid
grain fumigants to improve effectiveness in the upper layer of the
treated grain. In the event of the cancellation of EDB for this use,
fanners would have to switch to a less efficient liquid fumigant, 80
percent carbon tetrachloride/20 percent carbon disulfide or phosphine.
Carbon tetrachloride is presently under RPAR review. The additional
applications necessary for comparable control would result in both
increased expense and exposure hazard because of lower efficiency.
283
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Some level of mixing with untreated grain would be expected in movement
fronr on-farm storage, in further movement from the elevator, as well as
mixing in the milling or other processing operations. The level of EDB
(as organic bromide) in most processed products should, therefore, be
low.
Because of the changes in use patterns and the current availability of
more accurate, data on the volume of use, EPA's proposed regulatory
action regarding fumigation of stored grains should be reevaluated.
in. Spot Fumigation of Grain Mill ing Machinery
Three types of funrigant formulations containing EDB have been used in
the fumigation of milling machinery. The two liquid types contained
(CC14K ethylene dichloride (EDC) and EDB in different proportions. The
third type was a. gaseous mixture of 70 percent EDB and 30 percent methyl
bromide. Today,. virtually the entire EDB usage in this Industry involves
the application of this 70:30 mixture and only one company is currently
formulating it. The annual use of EDB for this purpose was originally
estimated at 465,000 1bs» Inten'm data from the study mentioned pre-
viously indicate this use at approximately 162,000 Tbs. The original
estimate was based primarily on the use of the EDB liquid funrigant
mixture and does not accurately reflect use of the present 70:30 mixture
in the milling industry. As with grain fumigation, the exposure resulting
from the amount of EDB known to be applied is much less than originally
estimated.
The primary alternative ta spot fumigation is genera/1 fumigation of the
entire structure. However, general fumigation is not feasible at.the
frequency necessary to obtain control equivalent to spot fumigation.
Most mills cannot close completely for several days at a time. To
obtain adequate insect control, mills would have to shut down four or
more times per year. In addition, specialized mills such as those lo-
cated in breweries cannot use either methyl bromide or phosphine in
their plants because of the corrosive effects of these fumigants on
materials in nonmilling areas of the facility. The use of EDB does not
pose this problem. The common use of manifold systems in spot fumi-
gations serves to remove applicators from sites of gas generation,
lessens the risk of spillage on applicators, and thus reduces hazards to
these personnel.
Good sanitation in milling areas is necessary for effective pest control;
however, it will not serve as an alternative to EDB use which is still
required since milling residues collect in unaccessible places in the
machinery. The only alternative is spot treatment with a funrigant.
Because of the changes in use patterns to the gaseous 70:30 mixture in
the past few years, the current availability of more accurate data on
volume of use, and the fact that proposed alternatives are not economi-
cally feasible and are associated with high risk, we strongly feel that
EPA's proposed regulatory action regarding spot fumigation of milling
machinery similarly should be reevaluated. EPA should strongly consider
and evaluate the use of protective clothing and other safety options to
minimize risk as an alternative to cancelling this critical use.
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IV. Quarantine Fumigation
The registration for post harvest coimiodity quarantine uses should be
continued for the following reasons:
1. As noted by EPA, there is presently no effective and practical
alternative to EDB for these uses. The assumption that irradi-
ation will be available by July 1983 is unrealistic. Although
EPA has evidently had interaction with specialists in the
field of Irradiation, we are unaware of data demonstrating the
feasibility of irradiation as a near term, viable, on-line
alternative for bulk quantities of fruit. Data concerning the
time-frames for getting on-line, chamber design, as well as
design and on-line costs should be made available. Research
has been conducted by USOA, as well as other groups in Hawaii,
California, Florida, Illinois, Massachusetts, and elsewhere,
to determine if fresh fruits and vegetables will tolerate
insect destroying rates of gamna Irradiation. Much of this
research is outlined in "The Proceedings of a Panel on The Use
of Irradiation to Solve Quarantine Problems in the International
Fruit Trade.* (Attached) The panel was organized by the
joint Foreign Agriculture Organization and the International
Atomic Energy Agency, Division of Atomic Energy in Food and
Agriculture, and held in Honolulu, Hawaii, in December 1970. A
petition (FAP 3045} from USOA to FDA requesting approval of
the use of gamma irradiation on papaya was submitted to FDA in
1973. The Food and Drug Administration has not acted on this
petition during the past eight-year period. A new petition
relating to these uses is in preparation. Additional research
is needed on mango and papaya as well as citrus and other
fruit to determine dosages necessary to control insect pests,
potential injury to fruit, and chemical or other changes in
fruit composition including'feeding studies on nutritional
value. This data collection will require considerable time
and expense.
2. EPA noted in its Notice of Determination that USDA's estimated
benefits of post harvest commodity treatments on grapefruits
for export market to Japan may be substantially overstated.
The benefits estimates were premised on the assumption that
the grapefruit export market to Japan will be lost if this
registered use is cancelled^ This assumption has been vali-
dated. Communication with the Government of Japan since the
publication of PD 2/3 indicates that Japan will not approve of
gamma irradiation as an alternative to EDB fumigation. The
refusal is primarily on the basis that irradiation at the
dosages used does not actually kill all fruitflies. In
addition, Japan has indicated that even the effective use of
gamma irradiation may still not be acceptable. However, they
did state that they would continue to accept EDB treated
fruit. (See attached letter of February 12, 1981, from
American Embassy, Tokyo.) Recent studies (SAND 79-1727,
Attachment B) suggest that dosages of 25 to 75 K-rads will
sterilize frultfly larvae, but not kill them. However, this
study did not statistically evaluate the effects of varying
dosages of gamma irradiation on fruitfly egg, larval and pupal
sterility and mortality, when infested commodities are sub-
jected to irradiation. The results are of limited value in
assessing gamma irradiation as an alternative to EDB for
commodity treatment.
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3. As Indicated in USOA's biologic and economic assessment report,
citrus and tropical fruits are imported from countries such as
Mexico, Haiti, Israel, and Morocco, thereby strengthening our
trade positions with then. Of the crops received from those
countries, cold treatment can only be used for oranges and is
limited to certain insect growth stages at the time the fruit
is harvested. The facilities for such treatment are not available
and must be constructed and approved before shipments could be
Initiated. Further, in the case of Mexican oranges in addition
to the expense involved, the delay of a minimum of three weeks
for cold treatment would bring their fruit into competition
with the California harvest and could virtually eliminate
Mexican fruit from the U. S. market. In these cases, the
Department's quarantine requirements cannot be net without the
use of EDB.
4. EDB fumigation chamber operation, construction, and personnel
safety specifications are available to meet or exceed proposed
QSHA safety standards. A revised section of the PPQ Treatment
Manual on EDB Fumigation Chambers was issued in July 1980.
Fumigation conducted at packing sheds in Texas and Hawaii cur-
rently meet, the proposed O.T3 ppm (time weighted average) for
worker exposure. Further, a study was recently conducted en-
titled, "Behavioral Effects of Prenatal Exposure to Ethylene
DM bromide." This study indicates that an exposure of 6.67 ppnr
ED& for four hours per day on alternate days throughout gesta-
tion did not result in an observable behavioral effect to the
study animals. Tests: determined that maternal behavior, sen-
sorimotor coordination* activity, passive avoidance, complex
learning and motivation were unaffected at exposure levels in
the offspring of exposed pregnant Long-Evans hooded rats.
(These documents are attached.)
5. The proposed cancellation of EDB post harvest fumigation of
citrus, tropical fruits and. vegetables should not occur. This
determination can be based upon the newly available safety
data contained herein and the lack of effective alternatives.
A reevaluation could be made when all the foregoing questions
have been resolved.
EPA should strongly consider and evaluate the use of protec-
tive clothing and other safety options to minimize risk as an
alternative to cancelling these critical uses.
V. Fumigation of Felled Logs
EDB is an important use in the control of bark beetles where non-
chemical control methods, including site selection and thinning,
are not viable control options. EDB 1s only used after an Infested
tree has been cut. If the tree is not treated to destroy the
beetles, they will emerge and attack adjacent trees. The proposed
alternative, endosulfan, is not specifically registered for the
particular insect of concern which Is the mountain pine beetle
(Dendroctonus ponderosae). There- 1s no efficacy data comparing Its
effectiveness with EDB. Lindane would be the preferred alternative
although it was not considered by EPA as a viable alternative due
to its RPAR status.
U.S. GOVERNMENT PRINTING OFFICE : 1983 0 - 418-574
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