United States Office of Prevention, Pesticides
Environmental Protection and Toxic Substances
Agency (7501C)
«&EPA Pesticide
Fact Sheet
Name of Chemical: Azoxystrobin
Reason for Issuance: Conditional Registration
Date Issued: February 7,1997
DESCRIPTION OF CHEMICAL
Chemical Name: Methyl(E_)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-
yloxy]phenyl}-3-methoxyacrylate
Common Name: Azoxystrobin
Trade Name: Heritage™ Fungicide, ICIA5504 Fungicide
Active Ingredient Codes:
EPA Pesticide Chemical Code: 128810
CAS Registry Number:
Year of Initial Registration: 1997
Function of Active Ingredient: Fungicide
U.S. Producer: Zeneca Ag Products
1800 Concord Pike
P.O. Box 15458
Wilmington, Delaware 19850-5458
302-886-1553
Classification of End-Use Products: Unclassified
DESCRIPTION OF USE PATTERNS
The Agency has issued one conditional registration for an
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end-use product containing the active ingredient, Azoxystrobin,
to Zeneca Ag Products. The use pattern of this product is as
follows:
Heritage Fungicide, EPA Reg. No. 10182-408 (50.0.%
Azoxystrobin). This product is formulated as wettable
granules. Azoxystrobin has been processed as a Reduced
Risk pesticide for Turf uses.
Sites: Golf courses and commercial turf farms.
Pests: Anthracnose (Colletotrichum graminicola), Brown
Patch (Rhizoctonia solani), Cool Weather Brown
Patch (Rhizoctonia cerealis), Fusarium Patch
(Microdochium nivale), Gray Snow Mold (Typhula
spp.), Leafspot (Drechslera spp. and/or Bipolaris
spp.), Melting Out (Drechslera spp. and/or
Bipolaris spp.), Necrotic Ring Spot (Leptosphaeria
korrae), Pink Snow Mold (Microdochium nivale),
Pythium Blight (Pythium spp.), Pythium Root Rot
(Pythium spp.), Red Thread (Laetisaria
fuciformis), Rhizoctonia Large Patch (Rhizoctonia
solani), Spring Dead Spot (Leptosphaeria korrae or
Gaeumannomyces graminis), Summer Patch
(Magnaporthe poae), Take-all Patch (Gaeumannomyces
graminis), Yellow Patch (Rhizoctonia cerealis),
and Zoysia Patch (Rhizoctonia solani and/or
Gaeumannomyces incrustana).
Type of Application: Ground spray.
SUMMARY OF SCIENCE FINDINGS
Azoxystrobin is the first of a new class of pesticidal
compounds called S-methoxyacrylates, which are derived from the
naturally-occurring strobilurins. Their biochemical mode of
action is inhibition of electron transport. The initial product
that is being registered is an end-use product (EUP) that is
formulated as water-soluble granules.
Azoxystrobin is of low acute and chronic toxicity to humans,
birds, mammals, and bees but is highly toxic to freshwater fish,
freshwater invertebrates, and estuarine/marine fish, and very
highly toxic to estuarine/marine invertebrates. The Azoxystrobin
degradate R234886 is practically nontoxic to Rainbow Trout and
daphnids, while the degradates R402173 and R401553 may be
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slightly toxic to daphnids. Azoxystrobin is not a carcinogen.
Some in-house environmental effects models indicate that
levels of concern (LOCs) for Turf uses of Azoxystrobin are
exceeded for small herbivores and several groups of fish and
aquatic invertebrates. However, these models all significantly
overestimate risk for these groups of organisms when applied to
Turf uses. Azoxystrobin is unlikely to appear in the estuarine
environment at concentrations that exceed Levels of Concern and
its degradates do not appear to have unreasonable toxicity for
freshwater animals. Therefore, the Agency believes that
registration Of Azoxystrobin for use on Turf does not pose an
unreasonable risk to any taxon of terrestrial or aquatic animals.
Laboratory studies show that Azoxystrobin is moderately
persistent in soil in the absence of light and potentially
moderately mobile in coarse textured soils (e.g., sand and loamy
sand soils). Upgradable, supplemental field dissipation studies
indicate that Azoxystrobin was moderately immobile and relatively
non-persistent under actual use conditions. The potential
mobility and persistence of some degradates, based on batch
equilibrium studies, aerobic soil metabolism, and some field
dissipation studies, are similar to pesticides with a potential
to leach into ground water under some conditions. A groundwater
advisory has, therefore, been placed on the label.
The registrant claims that Azoxystrobin is effective in
controlling Brown Patch, Pythium Blight, and Melting Out (Leaf
Spot) but does not control Dollar Spot. It has a single-site
mode of action so the labeling contains directions for use that
are intended to forestall the development of resistance to
Azoxystrobin among pests and that promotes the use of IPM.
A. Chemical Characteristics
The physico-chemical characteristics of the EUP that is
being registered are as follow.
Physical/Chemical Properties of Azoxystrobin Active Ingredient
Color: White
Molecular Formula: C22H17N305
Molecular Weight: 403.4
Physical State Powdery solid
Melting Point 116°C
Vapor Pressure: 1.1 x 10"13 kPa @ 25°C
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Solubility (water): 6.0 mg/1
Physical/Chemical Properties of Heritage Fungicide
Color:
Physical State:
Odor:
Bulk Density:
PH:
Stability:
Beige
Solid
None
0.58 g/cc
7.14 (1% dispersion)
Chemically stable for at least
14 days
at 54°C
The data provided fulfill all Product Chemistry data
requirements for registration of Azoxystrobin use on Turf, except
for Storage Stability (GRN 63-17; a one-year interim report has
been submitted, however) and do not indicate any unusual area of
concern.
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B. Toxicological Characteristics:
For Heritage Fungicide the Agency required six acute
toxicology studies. For the Technical product the Agency
required a complete battery of toxicological and adsorption/
distribution/metabolism/excretion (ADME) tests. The results are
as follow.
Test Name
Results
Tox. Category
I. Heritage Fungicide, EPA Reg. No. 10182-408 (50% a.i
A. Acute Testing
1. Acute Oral (Rat;
(81-1)
2. Acute Dermal
(Rat) (81-2)
3. Acute Inhalation
(Rat) (81-3)
LD50 >5000 mg/kg IV (CAUTION)
(males and
females)
LD50 >2000 mg/kg III (CAUTION)
NOEL <2000 mg/kg
LC50 >4.67 mg/L
(males and
females)
IV (CAUTION)
4. Primary Eye Irri-
tation (Rabbit)
(81-4)
Moderate eye
irritation,
persisting
to 72 hrs.
Ill
(CAUTION)
5. Primary Dermal
Irritation
(Rabbit)
6. Dermal Sensitiza-
tion Guinea Pig
(81-6)
II. Azoxystrobin Technical
A. Acute Testing
1. Acute Oral (Rat)
(81-1)
Slight dermal
irritant
Not a sensitizer
LD50 >5000 mg/kg
(males and
females)
IV (CAUTION)
N/A
IV (CAUTION)
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Acute Dermal LD50 >2000 mg/kg III (CAUTION)
(Rat) (81-2)
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Test Name
Results
Tox. Category
3. Acute Inhalation
(Rat) (81-3)
4. Primary Eye Irri-
tation (Rabbit)
(81-4)
Males: LC50=0.962
III (CAUTION)
mg/kg; Females:
LC50=0.698 mg/kg
III (CAUTION)
Slight to mode-
rate erythema and
slight chemosis,
clearing within
48 hours
5. Primary Dermal
Irritation (Rab-
bit) (81-5)
6. Dermal Sensitiza-
tion (Guinea
Pig) (81-6)
7. Neurotoxicity
of
(Rat) (81-8)
Slight erythema
and edema
Not a sensitizer
NOEL <200 mg/kg
(males and
females)
LOEL=200 mg/kg
(males and
females)
IV (CAUTION)
No indication
neurotoxicity,•
supplementary
study
Test Name
Results
Comments
B. Subchronic Testing
1. 90-Day Oral (Rat;
Toxicity (82-1)
2. 90-Day Oral (Dog)
NOEL=20.4 mg/kg/day
(males)
NOEL=20.4 mg/kg/day
(females)
LOEL=211.0 mg/kg/
day (males and
and females)
NOEL=50 mg/kg/day
(males and
females)
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3. 21-Day Dermal
(Rat) (82-2)
LOEL=250 mg/kg/day
(males and
females)
NOEL=1000 mg/kg/day
(males and
females)
LOEL not determined
Test Name
4. Neurotoxicity
(Rat) (82-7)
Results
NOEL=38.5 mg/kg/
day (males and
females)
LOEL=161 mg/kg/day
(males and
females)
Comments
No consistent
indications of
treatment-
related
neurotoxicity;
supplemental
study
C. Chronic Testing
Test Name
Results
1. 2-Year Feeding
(Rat) (83-1 and
83-2)
2. One-Year Oral
females)
(Dog) (83-1)
3. 2-Year Feeding
(Mice) (83-2!
4. Teratogenicity
(Rat) (83-3)
NOEL=300 ppm
LOEL (males)=750 ppm
LOEL (females)=1500 ppm
NOEL=25 mg/kg/day (males and
LOEL=200 mg/kg/day (males and
females)
NOEL=37.5 mg/kg/day (males)
NOEL=51.3 mg/kg/day (females)
LOEL=272.4 mg/kg/day (males)
LOEL=363.3 mg/kg/day (females)
NOEL (maternal)=(Not established)
LOEL (maternal)=25 mg/kg/day
NOEL
(developmental)=100
mg/kg/day
LOEL
(developmental)=100
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mg/kg/day
5. Developmental
(Rabbit) (83-3!
6. Multigeneration
(males)
(Rat) (83-4)
7. Oncogenicity
Feeding (Rat;
(83-5)
D. Mutagenicitv Testing
Test Name
NOEL (maternal) =150 mg/kg/day
LOEL (maternal) =500 mg/kg/day
NOEL (developmental) =500 mg/kg/day
LOEL (developmental) >500 mg/kg/day
NOEL (systemic) =33 mg/kg/day
LOEL (systemic) =163 .2 mg/kg/day
(males)
NOEL (systemic) =33 .2
mg/kg/day
(females!
(females!
LOEL (systemic)=170.6
mg/kg/day
NOEL (reproductive)=33
mg/kg/day
LOEL
(reproductive)=31.7
mg/kg/day
NOEL=18.2 mg/kg/day (males)
22.3 mg/kg/day (females!
LOEL=34 mg/kg/day (males)
117 mg/kg/day (females)
Results/Comment s
1. Mutation (Mouse Positive for forward gene mutation
(Lymphoma) (84-2) at the TK-locus in L5178 mouse
lymphoma cells
2. Mutagenic Poten-
tial (S. typhimu-
rium and E. coli)
(84-2)
3. Mutation (in vitro
Human Lympho-
cytes) (84-2)
No evidence of induced mutant
colonies over background
Evidence of a concentration-related
induction of chromosomal
aberrations over background
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No evidence of increased induction of
micronuclei in either sex
No evidence of increased unscheduled
DNA synthesis
Supplementary - minor qualitative
and quantitative differences in
metabolites
4. Mutation (Mouse
Micronucleus)
(84-2)
5. Unscheduled DNA
Synthesis (Rat
Hepatocytes)
(84-2)
E. Special Testing
1. Single-dose Whole
Body Radiography
(Rat) (85-1)
2. Single-dose Excre-
tion and Tissue
Retention (Rat)
(85-1)
3. 14-dose Excretion
and Tissue Reten-
tion (Rat) (85-1)
4. Biotransformation
(Rat) (85-1)
5. In Vivo Percuta- There was minimal percutaneous
neous EUP Absorp- absorption
tion (Rat) (85-2)
Absorbed Azoxystrobin appeared to be extensively metabo-
lized in the rat. It is proposed that hydrolysis and subsequent
glucuronide conjugation is the major metabolic pathway.
C. Risk Assessment Endpoints
Assessment
Results/Comment s
1. Acute Dietary
Exposure
(No appropriate endpoint;
2. Short Term Dermal Not required
Exposure
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3. Intermediate Term Not required
Dermal Exposure
4. Chronic Dermal
Exposure
5. Inhalation Expo-
sure
Not required
Not required at this time
6. Reference Dose
0.18 mg/kg/day
7. Carcinogenicity Carcinogenicity not likely
Classification
8. FQPA
No identified increase in
susceptibility in infants
In general, Azoxystrobin (both the Technical and the EUP) is
of low to very low acute toxicity. The Technical is also of low
to very low subchronic and chronic toxicity and is not likely to
be a carcinogen.
The only Toxicology data gaps that exist for Azoxystrobin
use on Turf are upgrading of the Acute Oral Neurotoxicity (Rat)
study (GRN 81-8) and the Subchronic Neurotoxicity (Rat) study
(GRN 82-7) with confirmatory data. The registrant has provided
the required data to do so.
D. Residue Chemistry
Residue chemistry data were not required for this regis-
tration since there are no food uses associated with it.
E. Occupational and Residential Exposure
Occupational and residential assessments were not performed
due to lack of toxicity endpoints of concern.
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F. Dietary Risk
Dietary exposure assessments were not performed because the
proposed registration does not contain food uses. Dietary
exposure from drinking water is conservatively estimated at 10%
of the RfD due to lack of data. Exposure to Azoxystrobin is
therefore not expected to exceed the level of concern from use on
commercial Turf and golf courses.
G. Environmental Fate Characteristics:
The Agency required a complete battery of Environmental Fate
studies. The company also voluntarily submitted additional data
from their internal testing to aid the Agency in understanding
the fate of Azoxystrobin in the environment. The results of the
required studies are as follow.
1. 161-1 Hydrolysis - Azoxystrobin will be stable to hydrolysis
in aquatic environments.
2. 161-2 Photodegradation in Water - An upgradable supplemental
study indicates that Azoxystrobin should photodegrade (half-
life = 11 to 17 days) in aquatic environments.
3. 161-3 Photodegradation on Soil - Azoxystrobin should
photodegrade (half-life = 11 days) in terrestrial
environments.
4. 162-1 Anaerobic and Aerobic Soil Metabolism - An upgradable
supplemental study indicates that Azoxystrobin should be
moderately persistent (half-life = 72 to 164 days) in
terrestrial environments.
5. (Not a Subdivision N guideline study) Microbial Effects -
Ancillary data which indicate that Azoxystrobin should not
affect microbe-mediated nitrogen metabolism and respiration.
6. 163-1 Adsorption and Desorption of Azoxystrobin in Soil -
Azoxystrobin exhibits a range of binding affinities
dependent upon soil textures. Azoxystrobin exhibits
relatively low binding affinities (Kd = 1.5 to 4 ml/g) on
coarse textured soils (e.g., loamy sand and sand) and higher
binding affinities (Kd = 5 to 23 ml/g) on finer textured
soils.
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7. 163-1 Adsorption and Desorption of the Azoxystrobin
Degradates R234886, R401553, and R402173 in Soil - These
degradates exhibited low binding affinity (Kd generally less
than 5 ml/g) in most soils. Hence, these degradates have
the potential to be mobile in terrestrial and aquatic
environments.
8. 164-1 Soil Dissipation - Several upgradable supplemental
studies, using different soils, indicate that Azoxystrobin
had a range of 50% field dissipation time (DT50) of 8 to 34
days. The first-order dissipation half-life of Azoxystro-
bin ranged from 28 to 85 days. Major transformation
products of Azoxystrobin were R230310, R234886, R401553, and
R402173. Azoxystrobin and R234886 were detected up to 371
days after treatment. The transformation product R234886
was detected in deep soil layers (6 to 18 inches).
The dissipation of Azoxystrobin appears to predominantly be
dependent on photodegradation and secondarily dependent on
microbial metabolism. It is moderately persistent in soils under
some conditions (absence of light) and shows characteristics that
lead to concern that dissipation of degradates (but not parent
compound) could occur in part via mobility in ground and surface
waters. Upgradable supplemental field dissipation studies
indicate that Azoxystrobin is relatively immobile and relatively
non-persistent under actual use conditions.
Review of the Environmental Fate data requirements for
Azoxystrobin use on Turf indicate that upgrading of the
Photodegradation in Water (CRN 161-2), Aerobic Soil Metabolism
(CRN I62-I), and Terrestrial Field Dissipation (CRN 164-1)
studies, plus submission of Droplet Size Spectrum (CRN 201-1) and
Drift Field Evaluation (CRN 201-2) data are necessary. The
registrant has provided upgrade data for the first three studies
and indicated that they will provide the latter two studies.
H. Ecological Effects Characteristics:
For Azoxystrobin Technical the Agency required a complete
battery of wildlife studies and the company voluntarily ran
additional studies on the parent compound and its degradates.
Test Name Results/Comments
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1. Avian Acute Oral Toxicity (LD50) (71-1)
a. Bobwhite >2000 mg/kg Practically
nontoxic
b. Mallard >250 mg/kg Not determined, study
is
Suppl
ement
al
2. Avian Subacute Dietary Toxicity (LC50) (71-2)
a. Bobwhite >5200 ppm
Practicall
y nontoxic
b. Mallard >5200 ppm Practically
nontoxic
3. Avian Reproduction (Chronic, TGAI) (71-4)
a. Mallard NOEC=1200 ppm
LOEC=3000 ppm
b. Bobwhite Not determined Study invalid; data
gap
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Test Name Results/Comments
4. Mammalian Acute Toxicity (TGAI)
a. Oral (Rat) LD50 >5000 mg/kg Practically
nontoxic
5. Mammalian Chronic Toxicity (TGAI)
a. Dietary (Rat) NOEC=300 ppm
LOEC=1500 ppm
b. Dietary (Rabbit) NOEC=16,500 ppm
LOEC>16,500 ppm
6. Nontarget Insect Acute Contact Toxicity (141-1)
a. Honey Bee (TGAI) LD50 >200 u/bee Practically nontoxic
b. Honey Bee (TEP) LD50 >200 u/bee Practically nontoxic
7. Other Invertebrates (not required; no CRN)
a. Earthworm (TGAI) LC50=278 mg ai/kg
b. Hoverfly (25% ai) Number of larva produced was signifi-
cantly adversely affected at test equi-
valent of 0.22 Ib. ai/acre
c. Carabid beetle No adverse effects at test equivalent of
(23.7% ai) 0.22 Ib. ai/acre
8. Freshwater Fish Acute Toxicity (TGAI) (72-1)
a. Rainbow Trout LC50=0.47 ppm Highly toxic
b. Bluegill LC50=1.1 ppm Moderately toxic
9. Freshwater Invertebrates, Acute (TGAI) (72-2)
a. Waterflea EC50=259 ppb Highly toxic
10. Freshwater Fish Early Life-stage (Chronic) Toxicity (TGAI)
(72-4)
a. Fathead Minnow NOEC=147 ppb
LOEC=193 ppb
11. Freshwater Aquatic Invertebrates Life-cycle Toxicity
(Chronic, TGAI) (72-4)
a. Waterflea NOEC=44 ppb
LOEC=84 ppb
12. Freshwater Organism Acute Toxicity (Degradates)
a. Rainbow Trout EC50/LC50 >150 Practically nontoxic;
ppm degradate=R234886
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b. Waterflea EC50/LC50 >190 Practically nontoxic;
ppm degradate=R234886
c. Waterflea EC50/LC50 >50 Slightly toxic;
ppm degradate=R401553
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Test Name
Results/Comment s
12. Freshwater Organism Acute Toxicity (Degradates) (cont.)
d. Waterflea EC50/LC50 >50 Slightly toxic;
ppm degradate=R402173
13. Estuarine/Marine Fish Acute Toxicity (TGAI) (72-3)
a. Sheepshead
Minnow
LC50=0.67 ppm
Highly toxic
14. Estuarine/Marine Invertebrate Acute Toxicity (TGAI) (72-3!
a. Mysid Shrimp
b. Pacific Oyster
(larvae)
LC50=56 ppb
LC50=1300 ppb
Very highly toxic
Moderately toxic
15. Nontarget Terrestrial Plant Seedling Emergence Toxicity
(Tier I, TEP) (I22-I)
a. Corn
b. Meadow fescue
c. Purple Nutsedge
d. Winter Wheat
e. Carrot
f. Soybean
g. Cocklebur
h. Morning Glory
i. Rape
j. Sugar Beet
k. Velvetleaf
14.4% inhibition
8.6%
5.3%
24.6% inhibition
33.2%
10.2% "
16.1% "
10.1% "
27.2% "
11.2% "
14.8% "
16. Nontarget Terrestrial Plant Vegetative Vigor Toxicity
(Tier I, TEP) (I22-I)
a. Corn
b. Purple Nutsedge
c. Winter Wheat
d. Wild Oat
e. Soybean
f. Cocklebur
g. Morning Glory
h. Rape
j. Sugar Beet
k. Velvetleaf
8.7% inhibition
2.9% "
4.9% "
11.4% "
0.3%
0.3%
0 %
6.7%
1.3%
0.7% "
17. Nontarget Terrestrial Plant Seedling Emergence Toxicity
(Tier II, TEP) (123-1)
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a. Carrot EC25=0.59 Ib ai/A
EC05=0.17 Ib ai/A
b. Rape EC25=3.2 Ib ai/A
EC05=0.55 Ib ai/A
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Test Name Results/Comments
18. Nontarget Aquatic Plant Growth Toxicity (Tier II, TGAI)
(123-2)
a. Duckweed EC50= 3 .4 ppm
NOEC=0.8 ppm
b. Green algae EC50= 0.1 ppm
NOEC=0.02 ppm
c. Marine diatom EC50= 0.5 ppm
NOEC=0.1 ppm
d. Freshwater EC50= 0.5 ppm
diatom NOEC=0.02 ppm
e. Blue-green algae EC50=13 ppm
NOEC=9 ppm
In general, acute toxicology studies (using the TGAI)
indicate that Azoxystrobin is practically nontoxic to birds,
mammals, and bees; highly toxic to freshwater fish, freshwater
invertebrates, and estuarine/marine fish; and very highly toxic
to estuarine/marine invertebrates. Available acute toxicity on
Azoxystrobin degradates indicate that R234886 is practically
nontoxic to Rainbow Trout and daphnids and R401553 and R402173
may be slightly toxic to daphnids.
Acute risk estimates were derived by use of in-house
modeling software. For use on Turf, no acute risk Levels of
Concern (LOCs) for birds or mammals are exceeded when the maximum
number of applications and maximum Estimated Environmental
Concentrations (EECs) are assumed. Using the GENEEC modeling
program, for fish and aquatic invertebrates the acute high risk
LOCs are exceeded only for estuarine/marine invertebrates for
multiple applications. However, GENEEC was not designed to model
Turf uses and the estimate for estuarine/marine invertebrates is
believed to be about a six-fold overestimate. Using that
correction factor no acute aquatic LOCs are presumed to be
exceeded for use of Azoxystrobin on Turf.
Chronic studies using the TGAI established the following
respective No Observed Effect Concentration (NOEC) and Lowest
Observed Effect Concentration (LOEC) values: 300 and 1500 ppm
for small mammals, with an endpoint effect of reduced pup
weights; 1200 and 3000 ppm for Mallards, with an endpoint effect
of reduced egg laying; and 44 and 84 ppb for freshwater fish,
with an endpoint effect of number of young produced. A Maximum
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Allowable Toxicant Concentration (MATC) of 168 ppb was
established for freshwater fish, based on adverse effects on
larvae length.
Modeling of Chronic risks indicates that the chronic LOG for
birds is not exceeded by data that are currently available to the
Agency, but the Bobwhite reproduction study requirement has not
yet been satisfied. With mammals, using the FATE modeling
program, the chronic risk to small herbivores is exceeded if the
maximum number of applications and the maximum EEC are assumed
but there is no exceedance if the mean EEC is assumed and no
exceedance in any scenario for insectivores. Since the FATE
modeling program overestimates risks for commercial Turf use, the
LOG exceedance that was calculated for small herbivores is
believed to be an artifact of the program rather than a real
concern. Using the GENEEC model, the restricted use and
endangered species LOCs are exceeded for freshwater fish,
freshwater invertebrates, and estuarine/marine fish for multiple
applications, and for estuarine/marine invertebrates for both
single and multiple applications. However, the GENEEC modeling
software is overly conservative for Turf and may provide up to a
six-fold overestimate of EECs for Azoxystrobin use on this site.
Therefore, the Agency believes that no acute or chronic LOCs for
aquatic organisms are actually exceeded.
The only Environmental Effects data gap that exists for
Azoxystrobin use on Turf is Avian Reproduction (Bobwhite)
(Chronic, TGAI) (71-4). This study is being repeated by the
manufacturer.
I. Performance Characteristics:
Data provided by the manufacturer indicate that end-use
products (EUPs) containing Azoxystrobin provide good control of
the Turf fungal pests Brown Patch, Pythium Blight, and Melting
Out (Leaf Spot) but do not control Dollar Spot.
SUMMARY OF MAJOR DATA GAPS
The only Product Chemistry data gap that exists for
Azoxystrobin use on commercial Turf is submission of a two-year
Storage Stability (CRN 63-17) study. A one-year interim report
has been submitted and the company has informed the Agency that
the study is on-going.
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The only Toxicology data gaps that exist for Azoxystrobin
use on commercial Turf are upgrading of the Acute Oral Neuro-
toxicity (Rat) study (CRN 81-8) and the Subchronic Neurotoxicity
(Rat) study (CRN 82-7). The registrant has provided the required
data to do so.
The outstanding Environmental Fate requirements for
Azoxystrobin use on Turf are upgrading of the Photodegradation in
Water (CRN 161-2), Aerobic Soil Metabolism (CRN 162-1), and
Terrestrial Field Dissipation (CRN 164-1) studies, plus the
submission of Droplet Size Spectrum (CRN 201-1) and Drift Field
Evaluation (CRN 201-2) data.
The only Ecological Effects data gap that exists for Azoxy-
strobin use on Turf is Avian Reproduction (Bobwhite) (Chronic,
TGAI) (71-4).
LABEL REQUIREMENTS
Because the Agency feels that the Environmental Fate data
submitted in support of the registration of Azoxystrobin indicate
that one of its degradates has the potential, under some circum-
stances and in some soils, to be moderately persistent and
mobile, the following groundwater statement is required on the
product labeling:
"Degradates of this chemical have properties and
characteristics associated with chemicals detected in
groundwater. The use of this chemical in areas where
soils are permeable, particularly where the water table
is shallow, may result in groundwater contamination."
PUBLIC INTEREST FINDING
Azoxystrobin has been determined, by the U.S. Environmental
Protection Agency, to be a Reduced Risk pesticide, for use on
commercial Turf.
Facts favorable to Azoxystrobin are that it has low
application rates and has application intervals that are
comparable to or longer than most alternatives. It also has a
broad control spectrum and a new mode of action that should allow
it to be used in resistance management strategies and against
fungi that have developed resistance to other fungicides.
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Azoxystrobin is additionally of low acute and chronic toxicity to
humans and is unlikely to be a carcinogen. It is also of low
acute and chronic toxicity to birds, mammals, and bees.
Facts unfavorable to Azoxystrobin are that it does not
control Dollar Spot, a major Turf pest. It is also highly toxic
to freshwater fish and invertebrates, highly toxic to
estuarine/marine fish, and very highly toxic to estuarine/marine
invertebrates. Additionally, environmental fate data lead to
some Agency concern that degradates of Azoxystrobin could be a
threat to reach groundwater under some meteorological and soil
conditions.
The risk to estuarine/marine animals from Turf use is very
low, however. Further, Azoxystrobin degradates that have been
tested are practically nontoxic to Rainbow Trout and only
slightly toxic, at most, to daphnids. In-house modeling
indicates only marginally significant risk to freshwater animals
and small herbivores resulting from commercial Turf use and these
are substantial overestimates of risk because the models are not
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designed for Turf uses. Also, the label will contain a ground
water advisory to indicate the Agency's concern about possible
soil persistence and mobility of Azoxystrobin.
CONTACT PERSON AT EPA
Mailing address:
Cynthia L. Giles-Parker
Product Manager (22)
Fungicide-Herbicide Branch
Registration Division (H7505C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, W. W.
Washington, B.C. 20460
Office location and telephone number:
Room 229, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22022
703-305-7740
DISCLAIMER: The information in this Pesticide Fact Sheet is for
information only and is not to be used to satisfy data require-
ments for pesticide registration. The information is believed to
be accurate as of the date on the document.
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