(a
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
% WASHINGTON, D.C. 20460
%
OFFICE OF
PREVENTION, PESTICIDES AND
June 30, 2005 toxic substances
MEMORANDUM
SUBJECT: Ecological Hazard and Environmental Risk Assessment of Bromine and Sodium
bromide for the Reregistration Eligibility Decision (RED) Document
Case No.: 4015-18801 DP Barcode: 315376
FROM: Srinivas Gowda, Microbiologist/Chemist
Risk Assessment and Science Support Branch (RASSB)
Antimicrobials Division (7501C)
TO: Mark Hartman, Branch Chief
Benjamin Chambliss, Team Leader
ShaRon Carlisle, Chemical Review Manager
Myron Ottley, Risk Assessor
Regulatory Management Branch II
Antimicrobials Division (7501C)
Sanyvette Williams, Science Coordinator
Antimicrobials Division (7501C)
THRU: Siroos Mostaghimi, Team Leader, Team 1
Risk Assessment and Science Support Branch (RASSB)
Antimicrobials Division (7501C)
Norman Cook, Branch Chief
Risk Assessment and Science Support Branch (RASSB)
Antimicrobials Division (7501C)
Chemical Name PC Code CAS # Common Name
Bromine 008701 7726-95-6 Bromine Gas (Br)
Sodium bromide 013907 7647-15-6 Bromide salt of sodium (NaBr)
Attached is the Ecological Hazard and Environmental Risk Assessment of Bromine and
Sodium bromide for incorporation into the Reregistration Eligibility Decision (RED) document.
©
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ECOLOGICAL HAZARD AND ENVIRONMENTAL RISK ASSESSMENT
Bromine and Sodium Bromide
CASE 4015-18801
PC Codes 008701 (Bromine) and 013907 (Sodium Bromide)
Submitted by:
Srinivas Gowda
Risk Assessment and Science Support Branch
Antimicrobials Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460
June 30,2005
EPA Barcode code: 315371
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Ecological Hazard and Environment Risk Assessment
Bromine and Sodium Bromide
Bromine (PC Code 008701) and Sodium bromide (PC Code 013907) are used for a
variety of antimicrobial uses. Currently, all registered uses of bromine are indoor (food, non-
food, medical, and residential). Bromine is used in water filters to purify drinking water. It also
is used as a general disinfectant and sanitizer in indoor, non-food contact areas such as
commercial establishments, hospitals and households, to control bacteria and fungi. In water and
living organisms, bromine reacts with other compounds to form bromides. Sodium bromide is
used as a water disinfectant, sanitizer, slimicide, bactericide, algicide, fungicide, and
molluscicide control agent. Registered uses include aquatic non-food industrial (commercial and
industrial recirculating water-cooling systems, wastewater treatment, industrial once-through
water cooling systems, pulp and paper mill water systems) aquatic non-food residential
(ornamental ponds/aquaria, swimming pool water systems, domestic/commercial nonpotable
water), indoor food (food processing water systems), and indoor non-food
(pasteurizer/warmer/cannery cooling water systems).
I. Ecological Toxicity Data
In addition to estimating risks to human health, the Agency also assesses risks to
terrestrial animals, aquatic organisms, and plants. The toxicity endpoints presented below are
based on the results of ecotoxicity studies submitted to EPA to meet the Agency=s data
requirements for the uses of bromine and sodium bromide.
A. T oxicity to T errestrial Animals
In order to establish the toxicity of bromine and sodium bromide to avian species for
indoor and aquatic uses, the Agency requires an acute oral toxicity study using the technical
grade active ingredient (TGAI). The preferred test species is either mallard duck (a waterfowl) or
bobwhite quail (an upland game bird). The Agency has granted waivers for avian studies using
bromine. Standard avian tests would not provide meaningful and useful toxicity data since
bromine is a highly volatile, corrosive liquid chemical. The results of two acute oral toxicity
studies, using sodium bromide, are provided in the following table (Table 1).
(1) Birds, Acute and Subacute
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Table 1. Acute Oral Toxicity of Sodium Bromide to Birds
Species
Chemical.
% Active
Ingredient
(a.i.)
Endpoint
(mg/kg)
Toxicity
Category
Satisfies
Guidelines/
Comments
Reference
(MRII)
No.)
Mallard duck
(Anas
platyrhynchos)
Sodium
bromide, 97%
LD50>2150
Practically
non-toxic
Yes
$ core study
$21-day test
duration
406699-01
Bobwhite quail
(Colinus
virginianus)
Sodium
bromide,
99.23%
LD50>2250
Practically
non-toxic
Yes
$ core study
$ 14-day test
duration
406708-11
The results indicate that sodium bromide is practically non-toxic to avian species on an
acute oral basis. The studies fulfill guideline requirements (71-1/OPPTS 850.2100).
A subacute dietary study using the TGAI may be required on a case-by-case basis
depending on the results of lower-tier ecological studies and pertinent environmental fate
characteristics in order to establish the toxicity of a chemical to avian species. This testing was
required for the aquatic uses of sodium bromide. Results of these studies are provided in
Table 2.
Table 2. Subacute Dietary Toxicity of Sodium Bromide to Birds
Species
Chemical,
% Active
Ingredient
(a.i.')
Endpoint
(ppm)
Toxicity
Category
Satisfies
Guidelines/
Comments
No#
Mallard duck
(Anas
platyrhynchos)
Sodium
bromide,
99.23%
LD50>5633
Practically
non-toxic
Yes
$ core study
$ 8-day test
duration
406708-12
Bobwhite quail
(Colinus
virginianus)
Sodium
bromide,
99.23%
LDs0>5633
NOEC =1784
Practically
non-toxic
Yes
$ core study
$ 8-day test
duration
406708-13
2
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The results indicate that sodium bromide is practically non-toxic to avian species on a
subacute dietary basis. The studies fulfill guideline requirements (71-2/OPPTS 850.2200).
(2) Mammals, Acute, Subchronic, and Developmental Toxicity
Wild mammal testing is not routinely required by the Agency. In most cases, rat toxicity
values obtained from studies conducted to support data requirements for human health risk
assessments substitute for wild mammal testing. These toxicity values are reported below (Table
3). Further information on the mammalian toxicology of bromine and sodium bromide may be
found in the Toxicology Chapter of this RED document.
Table 3. Acute, Subchronic and Developmental Toxicity of Bromine and Sodium Bromide
to Mammals (excerpted from Toxicology Chapter)
Guideline No.
Study Type
MRIDNo.
Results
Tox. Cat
'81-1
(OPPTS870.1100)
Acute Oral
Sodium Bromide 99.23%
40670804
LDjo 4.5 g/kg Male
LDjo 3.9 |^kg Female
LD50 4.2 g/kg combined
III
'81-2
(OPPTS 870.1200
Acute Dermal
Sodium Bromide 46%
46083032
LDS0 >2.0 g/kg
10
'81-3
Acute Inhalation
study not
available
'81-4
(OPPTS 870,2400)
Primary Eye Irritation
sodium bromide 46%
46083033
40670806
mild conjuctival irritation found in 6/6
animals, which persisted for 72 hr in
1 /6 animals. No effects at 96 hr.
III
'81-5
(OPPTS 870.2500)
Primary Dermal Irritation
sodium bromide 46%
46083034
very mild erythema on 1 /6 animals,
cleared by 24 hr. No irritation fount at
other times. P.I.I. = 1.0
IV
•81-6
(OPPTS 870.2600
Dermal Sensitization
study not
available
•81-8
(OPPTS 870.6200)
Acute and Subchronic
Neurotoxicity
study not
available
'82-1
(OPPTS 870.3100)
Oral Subchronic
Bromine 38%
418336-01
NOAEL=20 mg/kg/day
LOAEL=200mg/kg/day
'83-3
(OPPTS 870.3700)
Developmental Toxicity
sodium bromide 99.84%
557946-01
Maternal Toxicity:
NOEL= 1 OOmg/kg/day
LOAEL=300mg/kg/day
Developmental Toxicity;
NO AEL= 1 OOmg/kg/day
LOAEL=3O0mg/kg/day
3
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B. Toxicity to Aquatic Animals
The Agency requested that aquatic toxicity studies be conducted with hypobromous acid
since, under typical use conditions, hypobromous acid is formed and is essentially the active
ingredient which is introduced into the aquatic environment from the microbicide use of sodium
bromide. Because hypobromous acid is formed from both bromine chloride and sodium bromide
when added to water, studies using technical bromine chloride (100% a.i.) can be used to support
the data requirements for aquatic organism testing.
(1) Freshwater Fish, Acute
In order to establish the acute toxicity of bromine and sodium bromide to freshwater fish,
the Agency requires freshwater fish toxicity studies using the TGA1. The preferred test species
are rainbow trout (a coldwater fish) and bluegill sunfish (a warmwater fish). Results of
freshwater fish acute studies, submitted for bromine and sodium bromide, are presented in
Table 4.
4
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Table 4. Acute Toxicity of Bromine and Sodium Bromide to Freshwater Fish
Species
Chemical,
% Active
Ingredient
(a.i.)
Endpoints
(ppm)
Toxicity
Category
Satisfies
Guidelines/
Comments
Reference
No.)
Bluegill sunfish
(Lepomis
macrochirus)
Sodium
bromide,
99.23%
lc50> 1000
NOEC = 1000
Practically
non-toxic
No
$ supplemental
study
$ 96-hr test
duration
$ static system
$ although
study
scientifically
sound, aquatic
studies with
hypobromus
acid required
406708-14
Bluegill sunfish
(Lepomis
macrochirus)
Bromine
chloride, 100%
LC5o = 0.52 as
bromine
NOEC = 0.30 as
bromine
Highly toxic
Yes
$ core study
$ 96-hr test
duration
$ static system
406699-03
Rainbow trout
(Salrno
gairdneri)
Sodium
bromide,
99.23%
lc50>iooo
Practically
non-toxic
No
$ supplemental
study
$ 96-hr test
duration
$ static system
$ although
study
scientifically
sound, aquatic
studies with
hypobromous
acid required
406708-15
Rainbow trout
(Salmo
gairdneri)
Bromine
chloride, 100%
LCjo = 0.31 as
bromine
NOEC = 0.10 as
bromine
Highly toxic
Yes
$ core study
$ 96-hr test
duration
$ static system
406699-02
The results from the two core studies (MRIDs 406699-03 and 406699-02) indicate that
bromine chloride, measured as bromine, is highly toxic to freshwater fish (both coldwater and
warmwater) on an acute basis. These studies fulfill guideline requirements (72-1/OPPTS
5
7
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850.1075). The remaining two studies (MRIDs 406708-14 and 406708-15) are scientifically
sound, but do not fulfill guideline requirements that require aquatic testing with hypobromous
acid.
(2) Freshwater Invertebrates, Acute
The Agency requires a freshwater aquatic invertebrate study using the TGAI to establish
the acute toxicity to freshwater invertebrates. The preferred test species is Daphnia magna.
Results of the two studies, submitted for bromine and sodium bromide, are provided in the
following table (Table 5).
Table 5. Acute Toxicity of Bromine and Sodium Bromide to Freshwater Invertebrates
Chemical.
Satisfies
Reference
Species
% Active
F.ndpoints
Toxicity
GttidepBes/
(MRID
Ingredient
ippm)
Category ,
Comments
No.)
1000
Practically
No
406708-16
(Daphnia magna)
bromide,
99.23%
NOEC = 1000
non-toxic
$ supplemental
study
$ 48-hr test
duration
$ static test
system
$ although study
scientifically
sound, aquatic
studies with
hypobromous
acid required
Results of the core study (MRID 406699-04) indicate that bromine chloride, measured as
bromine, is highly toxic to freshwater invertebrates. The guideline requirement has been fulfilled
(72-2, OPPTS 850.1010) by this study.
6
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(3) Estuarine and Marine Organisms, Acute
Acute toxicity testing with estuarine and marine organisms using the TGAI is required
when the end-use product is intended for direct application to the marine/estuarine environment
or effluent containing the active ingredient is expected to reach this environment. The preferred
fish test species is sheepshead minnow. The preferred invertebrate test species are mysid shrimp
and eastern oysters. This testing is required for sodium bromide based on the chemical=s use in
pulp and paper mills, once-through cooling towers, oil recovery drilling muds/packer fluids, and
secondary oil recovery injection waters. It is not required for bromine, as all of the currently
registered uses are indoor applications for which there are no effluents. In the submitted studies,
sodium bromide was combined with sodium hypochlorite to produce hypobromous acid. Results
of the three toxicity studies are presented in Table 6.
Table 6. Acute Toxicity of Sodium Bromide to Estuarine and Marine Organisms
Species
Chemical,
% Active
Ingredient
(a.i.)
Cndpoints
(ppm)
Toxicity
Category ^
Satisfies
Guidelines.'
Comments
Reference
(MRID
No.)
Sheepshead
minnow
(Cyprinodon
variegatus)
Sodium
bromide, 46%
LC50 = 0.19 as
bromine
NOEC = 0.11
Highly toxic
Yes
$ core study
$ 96-hr test
duration
$ flow-through
system
407010-03
Mysid shrimp
(Mysidopsis
bahia)
Sodium
bromide, 46%
LCSo = 0.18 as
bromine
NOEC < 0.037
Highly toxic
Yes
$ core study
$ 96-hr test
duration
$ flow-through
system
407010-01
Eastern oyster
(Crassostrea
virginica)
Sodium
bromide, 46%
EC5o = 0.47 as
bromine
NOEC < 0.068
Highly toxic
Yes
$ core study
$ 96-hr test
duration
$ shell
deposition
$ flow-through
system
407010-02
NOTE: Sodium bromide was combined with sodium hypochlorite (9.4%) to produce hypobromous acid.
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The results indicate that sodium bromide, measured as bromine, is highly toxic to
estuarine/marine organisms on an acute basis. The studies fulfill guideline requirements
(72-3/OPPTS 850.1035, 850.1055, and 850.1075).
(4) Aquatic Organisms, Chronic
Chronic toxicity testing (Fish early life stage, 72-4a/OPPTS 850.1400 and aquatic
invertebrate life cycle, 72-4b/OPPTS 850.1300) is required for pesticides when certain conditions
of use and environmental fate apply. This testing is not required for bromine and sodium
bromide. All of the currently registered uses of bromine are indoor applications for which there
are no effluents. Chronic testing of sodium bromide is not required based on results of the
residue monitoring studies that indicate that residues of sodium bromide (hypobromous acid) are
short-lived and are highly toxic on an acute basis. In addition, the environmental fate assessment
(see Environmental Fate Assessment Summary, Section 11A) prepared for bromine/sodium
bromide shows that sodium bromide (hypobromous acid) is likely to degrade quickly in soil and
water with ultimate biodegradation completed within a few weeks. Therefore, standard chronic
toxicity tests would not provide meaningful and useful toxicity data and are waived.
(5) Actual Aquatic Field Residue Monitoring
Aquatic residues monitoring studies in freshwater and estuarine/marine are required by
the Agency to determine the actual residues of sodium bromide, based on its industrial use in
once-through cooling systems. Two studies were submitted to meet the requirements.
The first study (MRID 407570-01) was an EPA-sponsored study conducted at an electric
power plant discharging to an estuarine/marine environment. A once-through cooling system is
employed at the plant. This study was designed to examine bromine chloride as a potential
substitute for chlorine when used in condenser cooling systems. Two 15-day trials were made
using continuous dose rates of BrCl and CI2. Application rates were 510 and 135 ppb BrCl.
The results of this study indicate that the highest discharge residue (104 ppb, measured at
the point of discharge) of bromine, as hypobromous acid, from an initial continuous application
of 510 ppb, exceeds the level of concern (LOC-1/2 LC50), based on the submitted studies, for the
mysid shrimp, 90 ppb, and the sheepshead minnow, 95 ppb.
The second study (MRID 410641-01) was conducted at a wastewater treatment plant
which discharges into a freshwater stream. The facility uses aeration followed by disinfection,
and in this study, chlorine in the absence of bromide, and chlorine with bromide (from sodium
bromide in both cases) were used in the disinfection.
The results of this study indicate that the highest bromine or hypobromous acid
concentration (1081.6 ppb) in the effluent exceeds the LOCs for all freshwater aquatic species at
8
(b
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the point of discharge. Residue concentrations as high as 135.2 ppb were detected 80 meters
downstream. Residues were no longer detectable between 80 and 130 meters downstream. By
130,180, and 500 meters downstream, however, all effluent concentrations are below the LOCs
for freshwater aquatic species.
The freshwater residue monitoring study is scientifically sound but does not fulfill all data
requirements (supplemental study). However, when considered in conjunction with the EPA-
sponsored study of 1977, both studies provide enough data on decline, dispersion, and
persistence of hypobromous acid (or bromine) from sodium bromide when used with chlorine, or
from bromine chlorine to fulfill all data requirements (72-7/OPPTS 850.1950).
C. Toxicity to Non-target Plants
Non-target plant toxicity testing is required for pesticides when certain conditions of use
and environmental fate apply. The following testing is required for bromine and sodium bromide
to support the once-through cooling tower use.
123-1 /850.4225 Seedling emergence dose-response in rice TEP
123-2/850.4400 Aquatic vascular plant dose-response toxicity - Lemna sp. TGAI or TEP
123-2/850.5400 Acute algal dose-response toxicity - 4 species TGAI or TEP
II. Risk Assessment and Characterization
Risk assessment integrates the results of the exposure and ecotoxicity data to evaluate the
likelihood of adverse ecological effects. One method of integrating the results of exposure and
ecotoxicity data is called the quotient method. For this method, risk quotients (RQs) are
calculated by dividing exposure estimates by ecotoxicity values, both acute and chronic:
RQ = EXPOSURE/TOXICITY
RQs are then compared to OPP=s levels of concern (LOCs). These LOCs are criteria
used by OPP to indicate potential risk to nontarget organisms and the need to consider regulatory
action. The criteria indicate that a pesticide used as directed has the potential to cause adverse
effects on nontarget organisms. LOCs currently address the following risk presumption
categories: (1) acute high - potential for acute risk is high, and regulatory action may be
warranted in addition to restricted use classification; (2) acute restricted use - the potential for
acute risk is high, but this may be mitigated through restricted use classification; (3) acute
endangered species - the potential for acute risk to endangered species is high, and regulatory
action may be warranted; and (4) chronic risk - the potential for chronic risk is high, and
regulatory action may be warranted. Currently, AD does not perform assessments for chronic
risk to plants, acute or chronic risks to nontarget insects, or chronic risk from granular/bait
formulations to mammalian or avian species.
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The ototoxicity test values (i.e., measurement endpoints) used in the acute and chronic
risk quotients are derived from the results of required studies. Examples of ecotoxicity values
derived from the results of short-term laboratory studies that assess acute effects are: (1) LC50
(fish and birds); (2) LD50 (birds and mammals); (3) EC50 (aquatic plants and aquatic
invertebrates); and (4) EC25 (terrestrial plants). Examples of toxicity test effect levels derived
from the results of long-term laboratory studies that assess chronic effects are: (1) LOEC (birds,
fish, and aquatic invertebrates); (2) NOEC (birds, fish and aquatic invertebrates); and (3) MATC
(Maximum Allowable Toxic Concentration) (fish and aquatic invertebrates). For birds and
mammals, the NOEC value is used as the ecotoxicity test value in assessing chronic effects.
Other values may be used when justified. Generally, the MATC (defined as the geometric mean
of the NOEC and LOEC) is used as the ecotoxicity test value in assessing chronic effects to fish
and aquatic invertebrates. However, the NOEC is used if the measurement endpoint is
production of offspring or survival.
Risk presumptions, along with the corresponding RQs and LOCs are tabulated below.
Risk Presumptions for Terrestrial Animals
Risk Presumption RQ LOC
Birds and Wild Mammals
Acute High Risk
EEC'/LCso or LD50/sqft2 or LDjo/day3
0.5
Acute Restricted Use
EEC/LC50 or LDjo/sqft or LDS0/day
(or LD50 < 50 mg/kg)
0.2
Acute Endangered Species
EEC/LC50 or LDso/sqft or LDjo/day
0.1
Chronic Risk
EEC/NOEC
1
1 Abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items
2 me/ft2 3 me of toxicant consumed/dav
I.D50 * wt. of bird LD50 * wt. of bird
Risk Presumptions for Aquatic Animals
Risk Presumption RQ
LOC
Acute High Risk
EEC'/LCso or ECjq
0.5
Acute Restricted Use
EEC/LCso or ECS0
0.1
Acute Endangered Species
EEC/LC50 or EC50
0.05
Chronic Risk
EEC/MATC or NOEC
1
EEC = (ppm or ppb) in water
10
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Risk Presumptions for Plants
Risk Presumption RQ
LOC
Terrestrial and Semi-Aquatic Plants
Acute High Risk
EEC'/EC25
EEC/EC50 or NOEC
Acute Endangered Species
Aquatic Plants
Acute High Risk
EEC /EC50
Acute Endangered Species
EEC/EC05 or NOEC
EEC = lab ai/A
EEC = (ppb/ppm) in water
A. Environmental Fate Assessment Summary (excerpted from the
Environmental Fate Science Chapter of this RED document)
In 1993, the Agency issued a RED on Bromine (EPA document: EPA-738-F-93-023) in
which it was stated: "The current use patterns of pesticide products containing bromine do not
result in environmental exposure. Therefore, the RED includes no discussion of bromine's
environmental fate." In the present RED environmental fate of both bromine and sodium
bromide are being assessed together.
Bromine as bromide is found in seawater at 65 ppm level while in the earth's crust it is
detected at 2.5 ppm level. (The elements by J. Emsley 1989, Oxford University press, pp 34-35),
Its major antimicrobials use is as a disinfectant and all the registered uses are indoor.
Pure bromine exists as a liquid. In aqueous solution, it reacts with water instantaneously
forming hydrobromic (HBr) acid and hypobromous acid (HOBr), The chemistry of bromine in
water is, therefore, that of hydrobromic and hypobromous acids of bromide (Br ) and
hypobromide (OBr ) species.
In the atmosphere it is moderately persistent and in water it can react with a number of
cations ions to form bromides and or hypobromides. In can be moderately persistent in soils,
although no experimental Kd are available to quantitatively assess binding with soils.
Henry Law Constant (HLC) for bromine is quite low ( 2.5 x 10"2 atm-m3/mol) so it less
likely to volatilize from aqueous medium to the air.
EPI Suite estimates that it is likely to biodegrade fast as is non-linear biodegradation.
11
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Ultimate biodegradation in soils/water can probably take place within a few weeks.
Estimated Log K0w value of 1.03 indicates that bromine is not likely to bioaccumulate in
aquatic organisms.
In aqueous medium, the chemistry and fate of sodium bromide is going to be the same as
bromide ion. When used, as a solid, its vapor pressure is very low (1.77 x 10"17 mm Hg) and is
not likely to volatilize into the air when in aqueous medium.
EPI Suite estimated that it is likely to biodegrade fast in soil and water. Ultimate
biodegradation can take place in few weeks.
Estimated Log K<,w of 0.63 is a strong indicator of little probability of bioaccumulation
with aquatic organisms.
B. Environmental Exposure and Ecological Risk Assessment
Freshwater and estuarine/marine aquatic organisms could potentially be exposed to
sodium bromide discharged into the aquatic environment. The Agency conducted modeling in
1993 and 2005 to estimate the exposure and environment risk resulting from such discharges.
In 1993, the Agency conducted Tier Ic EEC modeling (preliminary or lower tier exposure
assessment) for hypobromous acid. (Hypobromous acid is formed when sodium bromide is
added to water and is the actual toxic agent). Tier Ic EEC modeling determines the maximum
concentration likely to occur immediately downstream from an industrial (point source)
discharge site. EECs were evaluated for both Ahigh exposure® cases and Atypical® sites. The
calculated Ahigh exposure® EEC, i.e., cases of extreme exposure, for hypobromous acid as
bromine for all sites tested was 450 ppb (0.45 ppm). This result is comparable with the
previously mentioned residue monitoring studies, which showed high concentrations of
hypobromous acid as far downstream as 80 meters. The EECs for typical sites ranged from 0.38
ppb to 0.75 ppb (0.00038 to 0.00075 ppm).
RQ values are calculated using the predicted surface water EECs and measured endpoints
derived from the results of required studies. The resultant RQs are then compared to the LOCs.
The results are presented in the following tables for freshwater organisms (Table 7) and
estuarine/marine organisms (Table 8).
(1) 1993 Tier Ic EEC Modeling
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Table 7. Acute Risk Quotients for Freshwater Organisms
Species
High Exposure
Typical Exposure
LC50
(ppm)
EEC
(ppm)
RQ
(EEC/LC50)
LC50
(ppm)
EEC
(ppm)
m
(EEC/L
Cso)
Rainbow Trout
(Salmo gairdner)
0,31
0.45
1.45(a)
0.31
0.00038 to
0.00075
0.00122
to
0.00242
Bluegill Sunfish
(Lepomis
macrochirus)
0.52
0.45
0.87(a)
0.52
0.00038 to
0.00075
0.00073
1 to
0.00144
Water flea
(Daphnia magna)
1.07
0.45
0.42(b)
1.07
0.00038 to
0.00075
0.00035
5 to
0.00070
1
a = high risk, restricted use and endangered species LOCs have been exceeded,
b - restricted use and endangered species LOCs have been exceeded,
c = endangered species LOC has been exceeded,
d = none of the LOCs have been exceeded.
Table 8. Acute Risk Quotients for Estuarine/Marine Organisms
Species
High Exposure
Typical Exposure
LCS0
(ppm)
EEC
(ppm)
RQ
(EEC/LCgo)
LC50
(ppm)
EEC
(ppm)
RQ
(EEC/LC
so)
Sheepshead
minnow
(Cyprinodon
variegatus)
0.19
0.45
2.37(a)
0.19
0.00038 to
0.00075
0.00200 to
0.00395
Mysid shrimp
(Mysidopsis
bahia)
0.18
0.45
2.50(a)
0.18
0.00038 to
0.00075
0.00210 to
0.00417
Easter oyster
(Crassostrea
virginica)
0.47
0.45
0.96(a)
0.47
0.00038 to
0.00075
0.000809
to
0.001600
'a = high risk, restricted use and endangered species LOCs have been exceeded,
b = restricted use and endangered species LOCs have been exceeded,
c = endangered species LOC has been exceeded,
d = none of the LOCs have been exceeded.
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The results for high exposure sites indicate that the RQs exceed all of the LOCs for
freshwater fish (rainbow trout and bluegill sunfish) and for estuarine/marine organisms
(sheepshead minnow, mysid shrimp, and eastern oyster), but not for the freshwater invertebrate
Daphnia magna. Therefore, the Agency presumes high risk to freshwater fish and
estuarine/marine organisms at the point of discharge and downstream to 80 meters. However,
the results for Atypical® sites show that the RQs are well below all of the LOCs for both
freshwater and estuarine/marine organisms. This would indicate that hypobromous acid can be
used at typical sites most of the time, without producing effluents above LOCs. Since the
discharge of hypobromous acid is limited by the NPDES permit program, the Agency will be
able to control the discharge of hypobromous acid on a site-by-site basis so that toxic levels are
avoided.
(2) 2005 Probabilistic Dilution Modeling
The PDM4 Model was used to estimate exposure from once-through cooling tower uses.
The details of this model are found in the Environmental Modeling Chapter of this document. A
high-flow power plant (1000 +10 million gallons per day) was used as the scenario providing the
maximum concentrations of bromide in the receiving water, e.g., the Aworst case® scenario. It
was assumed that the chemical was being applied at the highest listed rate shown on any of the
sodium bromide product labels, and that all bromide was converted to available bromine.
Actual concentrations in receiving waters are likely lower, and will likely not show the increasing
trend indicated in Table 9, due to higher flow rates, lower conversion rate to available bromine,
and possible degradation/dissipation of available bromine by mechanisms other than hydrolysis.
A summary of concentrations over time is provided in Table 9. The concentrations selected for
analysis were the measured endpoints derived from the results of the required studies (see
Section I.B.)
The probability associated with exceedcnce once per year is 1/365 = 0.274%. Therefore,
in any given year, the two-day peak concentration of bromide in rivers receiving the discharge of
once-through cooling waters is expected to be less than 0.11 ppm. In any given year, the four-
day peak concentration is expected to be less than 0.037 ppm.
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Table 9. Percent Probability of Exceedence of Bromine in Rivers Receiving Discharge from
Low-Flow Power Plants Using Once-Through Cooling Systems
C oncciitrations
(ppm as bromine)
Probability Of Continuous Exceedence Ox er:
2 Days
4 Days
0.037
2.62
0.0689
0.068
0.787
0.00619
0.1
0.314
0.000983
0.11
0.246
0.000605
0.18
0.0645
0.0000416
0.19
0.0552
0.0000305
0.3
0.0144
0.00000207
0.31
0.0130
0.00000169
0.47
0.00362
0.000000131
0.52
0.00262
0.0000000687
1.07
0.000213
0.000000000454
C. Endangered Species Considerations
The Agency has developed the Endangered Species Protection Program to identify
pesticides whose use may cause adverse impacts on endangered and threatened species and to
implement mitigation measures that address these impacts. The Endangered Species Act requires
federal agencies to ensure that their actions are not likely to adversely affect individuals of listed
species or adversely modify designated critical habitat. To analyze the potential of registered
pesticide uses to affect any particular species, EPA puts basic toxicity and exposure data
developed for risk assessments into context for individual listed species and their locations by
evaluating important ecological parameters, pesticide use information, the geographic
relationship between specific pesticide uses and species locations, and biological requirements
and behavioral aspects of the particular species. A determination that there is a likelihood of
potential impact to a listed species may result in limitations on use of the pesticide, other
measures to mitigate any potential impact, or consultations with the Fish and Wildlife Service
and/or the National Marine Fisheries Service as necessary.
The PDM4 Model was used to estimate exposure from once-through cooling tower uses
(see Environmental Modeling Chapter of this document). The endangered species risk
assessment for a typical use of bromine and bromine chloride (hypobromus acid) did not result
in any LOC exceedences for terrestrial or aquatic animals. Therefore, bromine and sodium
bromide are not expected to adversely affect endangered/threatened terrestrial or aquatic animal
species or critical habitat (NLAA) under typical use conditions. A risk assessment was not
conducted for non-target plants due to the absence of toxicity data.
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A high-flow power plant (1000 + 10 million gallons per day) that discharges into a low-
flow surface stream was modeled as a "worst case" scenario in order to predict a maximum
concentration of bromide in receiving water. The model assumed the chemical was applied at
the highest registered label dosage and that all bromide was converted to available bromine. The
probability of a high exposure scenario is extremely low, however, the results indicate that LOCs
are exceeded for aquatic animals; freshwater fish (rainbow trout and bluegill sunfish) and for
estuarine/marine organisms (sheepshcad minnow, mysid shrimp, and eastern oyster), except for
the freshwater invertebrate Daphnia magna. Therefore, the Agency presumes high risk to
freshwater fish and estuarine/marine organisms at the point of discharge from a high-flow plant
and downstream to 80 meters.
This modeling would indicate that hypobromous acid can be used at typical sites most of
the time, without producing effluents above LOCs. Since the discharge of hypobromous acid is
limited by the NPDES permit program, the Agency will be able to control the discharge of
hypobromous acid on a site-by-site basis so that toxic levels are avoided. Other options include a
reduction of the maximum label dosage and/or reduced hypobromous acid use by high-flow
plants during periods of low water flow.
16
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BIBLIOGRAPHY
MRID
2003050
40669901
40669902
40669903
40669904
40670811
40670812
40670813
40670814
Citation
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40670815
Bowman, J.H. 1988. Acute Toxicity of Sodium Bromide Technical to Rainbow
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Unpublished data. Conducted by Analytical Bio-Chemistry Laboratories for
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40701001 Surprenant, D.C. 1988. Acute Toxicity of Hypobromous Acid to Mysid Shrimp
(Mysidopsis bahia) Under Flow-Through Conditions. Unpublished data.
Conducted by Springborn Life Science, Inc. for Industry Task Force.
40701002 Surprenant, D.C. 1988. Acute Toxicity of Hypobromous Acid to Eastern Oysters
(Crassostrea virqinica) Under Flow-Through Conditions. Unpublished data.
Conducted by Springborn Life Science, Inc. For Sodium Bromide/Bromine
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40701003 Surprenant, D.C. 1988. Acute Toxicity of Hypobromous Acid to Sheepshead
Minnow (Cyprinodon varieqatus) Under Flow-Through Conditions. Unpublished
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Chloride Industry Task Force.
40757001 Bongers, L.H., T.P. 0=Connor, and D.T. Burton. 1977. Bromine Chloride - An
Alternative to Chlorine for Fouling Control in Condenser Cooling Systems.
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Sign-off Date
DP Barcode No.
07/14/05
D315376
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