UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION

Environmental Fate and Ecological Risk Assessment

for Fenpyrazamine New Chemical Registration for 

Proposed Uses on Almonds, Pistachios, Lettuce, 

Strawberries, Bushberries, Caneberries, Ginseng, and 

Ornamentals

Chemical Formula: C17H21N3O2S

PC Code: 090109

CAS Number: 473798-59-3

Prepared by:

Gabe Rothman, Environmental Scientist

Justin Housenger, Biologist 

Reviewed by:

José Melendez, Chemist

Al Vaughan, Risk Assessment Project Leader, ERB5

Mah Shamim, Ph.D., Branch Chief, ERB5

United States Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave.

Mail Code 7507P

Washington, D.C. 20460
2

Table of Contents

1. Executive Summary...............................................................................................................................................5

1.1 Nature of Chemical Stressor..................................................................................................................5

1.2 Potential Risks to Non-target Organisms...............................................................................................6

1.2.1 Aquatic Animals and Plants...................................................................................................................6

1.2.2 Terrestrial Animals and Plants...............................................................................................................7

1.3 Risk Characterization.............................................................................................................................8

2. USE CHARACTERIZATION ..............................................................................................................................8

3. ENVIRONMENTAL FATE AND TRANSPORT CHARACTERIZATION.......................................................9

4. ECOLOGICAL TOXICITY CHARACTERIZATION.......................................................................................20

4.1 Receptors.............................................................................................................................................20

4.2 Ecosystems at Risk ..............................................................................................................................21

4.3 Assessment Endpoints .........................................................................................................................22

4.4 Ecological Effects Characterization.....................................................................................................22

4.4.1 Aquatic Effects ....................................................................................................................................23

 Freshwater Fish....................................................................................................................................31

 Freshwater Invertebrates......................................................................................................................32

 Estuarine/Marine Fish..........................................................................................................................33

 Estuarine/Marine Invertebrates............................................................................................................34

 Benthic (Sediment Dwelling) Invertebrates.........................................................................................35

 Vascular and Non-vascular Aquatic Plants..........................................................................................36

4.4.2 Terrestrial Effects ................................................................................................................................38

 Birds (Acute Toxicity).........................................................................................................................42

 Birds (Chronic Toxicity)......................................................................................................................42

 Mammals (acute toxicity) ....................................................................................................................43

 Mammals (chronic toxicity).................................................................................................................43

 Non-target Beneficial Insects...............................................................................................................44

 Other Non-target Terrestrial Organisms..............................................................................................44

 Terrestrial Plants..................................................................................................................................45

5. PROBLEM FORMULATION ............................................................................................................................46

5.1 Risk Hypotheses ..................................................................................................................................46

5.2 Conceptual Model................................................................................................................................47

5.3 Analysis Plan .......................................................................................................................................48

5.3.1 Measures of Exposure..........................................................................................................................48

5.3.2 Measures of Effects .............................................................................................................................49

5.3.3 Integration of Exposure and Effects.....................................................................................................49

6. EXPOSURE ANALYSIS....................................................................................................................................50

7. RISK CHARACTERIZATION...........................................................................................................................60

7.1 Risk Estimation - Integration of Exposure and Effects Data ...............................................................60

7.1.1 Non-target Aquatic Animals and Plants...............................................................................................60

a. Water Column Exposure: Acute and Chronic Risk to Animals...........................................................61

b. Sediment Exposure: Chronic Risk to Benthic Invertebrates................................................................64

c. Aquatic Plants......................................................................................................................................67

7.1.2 Non-target Terrestrial Animals............................................................................................................69

a. Acute and Chronic Risk to Birds.........................................................................................................69

b. Acute and Chronic Risk to Mammals..................................................................................................70

c. Non-target Beneficial Insects...............................................................................................................72

d. Risks to Terrestrial Plants....................................................................................................................73

7.2 Risk Description ..................................................................................................................................74

7.2.1 Risks to Aquatic Animals....................................................................................................................74

a. Potential for Acutely Toxic Exposures................................................................................................74
3

b. Potential for Chronically Toxic Exposures..........................................................................................75

7.2.2 Risks to Terrestrial Animals ................................................................................................................79

a. Potential for Acutely Toxic Exposures................................................................................................79

b. Potential for Chronically Toxic Exposures..........................................................................................80

7.2.3 Risks to Terrestrial Plants....................................................................................................................81

7.2.4 Review of Incident Data ......................................................................................................................81

7.2.5 Threatened and Endangered Species Concerns....................................................................................81

7.2.6 Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps............................83

a. Incidental Pesticide Releases Associated with Use .............................................................................83

b. Exposure for Aquatic Species......................................................................................................................83

c. Exposure for Terrestrial Species..................................................................................................................86

d. Effects Assessment ......................................................................................................................................86

 Age Class and Sensitivity of Effects Thresholds.................................................................................87

 Lack of Effects Data for Amphibians and Reptiles .............................................................................87

 Use of the Most Sensitive Species Tested ...........................................................................................88

8. IDENTIFICATION OF DATA GAPS ................................................................................................................88

9. REFERENCES ....................................................................................................................................................89

 Environmental Fate Studies..............................................................................................................89

 Ecological Effects Studies..................................................................................................................91

Open Literature and Government Reports.........................................................................................................96

Appendices

Appendix A. The Risk Quotient Method and Levels of Concern

Appendix B. Output of STIR Results

Appendix C. Output of SIP Results

Appendix D. Output of TerrPlant Results

Appendix E. Sample PRZM/EXAMS Input and Output Files

Appendix F. Formation of Fenpyrazamine Transformation Products in Environmental Fate 

Studies.

Appendix G. Toxicity Comparisons of Fenpyrazamine and Transformation Products
4

Table of Figures

Figure 1. Proposed degradation and dissipation pathways in soil. .............................................................................15

Figure 2. Proposed degradation and dissipation pathways in water. ..........................................................................17

Table of Tables

Table 1. Summary use information for fenpyrazamine, based on the proposed V-10135 4 SC Fungicide suspension 

concentrate label by Valent U.S.A.................................................................................................................................9

Table 2. Physical and chemical properties of fenpyrazamine.....................................................................................10

Table 3. Summary of fenpyrazamine environmental fate properties..........................................................................10

Table 4. Comparison of physical chemical properties of fenpyrazamine transformation products to parent 

fenpyrazamine. ............................................................................................................................................................18

Table 5. Taxonomic groups and test species evaluated for ecological effects in this screening-level risk assessment

.....................................................................................................................................................................................20

Table 6. Toxicity endpoints used in risk quotient calculations...................................................................................21

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine................................................23

Table 8. Toxicity Reference Values For Aquatic Organisms Exposed to Degradation Products of Fenpyrazamine. 30

Table 9. Toxicity Reference Values For Terrestrial Organisms Exposed To Fenpyrazamine....................................38

Table 10. Summary of PRZM/EXAMS input parameter values for physical chemical and fate properties used for 

fenpyrazamine surface water aquatic EECs.................................................................................................................50

Table 11. Crop management PRZM/EXAMS inputs used in aquatic exposure modeling. ........................................52

Table 12. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in surface water (ppb) for aerial 

applications of fenpyrazamine.....................................................................................................................................54

Table 13. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in surface water (ppb) for ground 

applications of fenpyrazamine.....................................................................................................................................55

Table 14. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in benthic pore water (ppb) for 

aerial applications of fenpyrazamine. ..........................................................................................................................55

Table 15. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in benthic pore water (ppb) for 

ground applications of fenpyrazamine.........................................................................................................................56

Table 16. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in sediment (mg fenpyrazamine/kg 

sediment, dry weight) for aerial applications of fenpyrazamine..................................................................................56

Table 17. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in sediment (mg fenpyrazamine/kg 

sediment, dry weight) for ground applications of fenpyrazamine. ..............................................................................57

Table 18. Terrestrial food item residue estimates for birds with proposed fenpyrazamine uses on various crops. ....58

Table 19. Terrestrial food item residue estimates for mammals with proposed fenpyrazamine uses on various crops.

.....................................................................................................................................................................................58

Table 20. TerrPlant derived EECs for dry and semi-aquatic areas resulting from proposed fenpyrazamine uses......59

Table 21. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to freshwater and estuarine/marine 

fish. ..............................................................................................................................................................................62

Table 22. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to freshwater and estuarine/marine 

invertebrates. ...............................................................................................................................................................63

Table 23. Chronic RQs for risk of fenpyrazamine exposure to freshwater benthic invertebrates1,2. ..........................65

Table 24. Chronic RQs for risk of fenpyrazamine exposure to estuarine/marine benthic invertebrates1,2,3................66

Table 25. RQs for evaluating toxic risk of fenpyrazamine exposure to vascular and non-vascular aquatic plants. ...67

Table 26. Dose-based RQs for birds due to exposure to proposed uses of fenpyrazamine. .......................................69

Table 27. Dietary-based RQs for birds due to exposure to proposed uses of fenpyrazamine.....................................70

Table 28. Acute dose-based RQs for mammals due to exposure to proposed uses of fenpyrazamine. ......................71

Table 29. Chronic dose-based RQs for mammals from exposure to proposed uses of fenpyrazamine. .....................71

Table 30. Chronic dietary-based RQs for mammals due to exposure to proposed uses of fenpyrazamine. ...............72

Table 31. RQs for terrestrial plants resulting from the propose uses of fenpyrazamine.............................................73
5

1. EXECUTIVE SUMMARY

This ecological risk assessment addresses the new active ingredient fenpyrazamine which is 

proposed to be used in conventional ground and aerial foliar applications on almonds, grapes, 

lettuce, and strawberries as major food uses as well as on ornamentals as the only major nonfood use. Additional IR-4 minor crop uses proposed for fenpyrazamine are conventional ground 

and aerial foliar applications on pistachio, bushberry, caneberry, and ginseng crops. Proposed 

maximum application rates of fenpyrazamine on crops range between 0.375 lbs. a.i./A – 1.089 

lbs. a.i./A with three to four retreatment intervals at a minimum of 7 seven days between 

applications specified on the draft product label.

1.1 Nature of Chemical Stressor 

The subject chemical addressed in this ecological risk assessment is identified by the chemical 

fenpyrazamine (PC Code 090109) with the chemical synthesis (IUPAC) name of S-allyl 5-

amino-2,3-dihydro-2-isopropyl-3-oxo-4-(o-tolyl)pyrazole-1-carbothiaote. Fenpyrazamine is a 

pyrazole fungicide intended to control a number of fungal diseases including brown rot, green 

fruit rot/jacket rot, botrytis bunch rot, lettuce drop, gray mold, and botrytis blight gray mold. 

Fenpyrazamine’s mode of action has not been fully elucidated, but it is thought to inhibit the 

generation of reproductive spores via inhibition of the germ tube and mycelium elongation.1 In

addition, pyrazole fungicides are known to inhibit the succinate-dehydrogenase enzyme which 

serves a critical mechanism as part of the citric acid cycle and providing a pathway for electronic 

transfer throughout the organism2. The trade name for this compound is V-10135 4 SC 

Fungicide (a suspension concentrate). The labeled formulation contains 43.6 percent of the 

active ingredient fenpyrazamine and 56.4 percent inert ingredients. 

Fenpyrazamine foliar applications using ground and aerial sprays may impact aquatic habitats 

within water bodies and ground water given that it possesses similar physical chemical properties 

and persistence as other chemicals which are known to translocate to these media. In addition, 

fenpyrazamine applications potentially result in dietary exposure and exposure to plants in the 

terrestrial environment given its moderate to high persistence in the environment. 

Fenpyrazamine is moderately persistent in alkaline aerobic soil with half lives ranging between 

38 and 49 days. However, fenpyrazamine degrades much slower in acidic aerobic soil, with 

half-lives between 201 – 801 days. In anaerobic acidic soil environments, half-lives are a little 

less at 128 days. Once reaching the water column, fenpyrazamine is moderately persistent to 

persistent, especially in acidic environments, with half-lives ranging from 12 days – 280 days 

under aerobic and anaerobic conditions. Fenpyrazamine’s rapid hydrolysis at pH9 (with a halflife of 12 days) and high stability at pH5 suggests that hydrolysis may mediate fenpyrazamine’s 

degradation in the environment. Fenpyrazamine (S-2188) degrades mainly to S-2188-OH, S2188-DC, and MCNI in soil and water. However, submitted ecotoxicity toxicity data as well as 

 

1 Citation: Footprint database. Accessible on-line: http://sitem.herts.ac.uk/aeru/footprint/en/Reports/2010.htm.

Accessed June 2012.

2 Citation: Fungicide Resistance Action Committee Classification on Mode of Action 2011. Accessible on-line: 

http://www.frac.info/frac/publication/anhang/FRAC%20MoA%20Poster%202011_final_HR.pdf

Accessed August 2012.
6

structural activity relationships (ECOSAR v.1.0) indicates that fenpyrazamine is at least an order 

of magnitude or more toxic than these degradates depending on the taxa. Therefore,

fenpyrazamine is considered the primary stressor in this risk assessment. Further information 

related to the justification of fenpyrazamine as the primary stressor is provided in Section 5.2.

1.2 Potential Risks to Non-target Organisms 

This is the Environmental Fate and Effects Division’s (EFED) national screening-level 

ecological risk assessment for the proposed registration of fenpyrazamine. A summary of the 

major conclusions and uncertainties of this assessment for aquatic and terrestrial receptors

respectively is included below. 

1.2.1 Aquatic Animals and Plants

Acute Risk Concerns: The results of this screening-level risk assessment suggest minimal acute 

risk of acute toxicity to freshwater and estuarine/marine fish and freshwater invertebrates based 

on runoff and spray drift from foliar applications to adjacent surface waters. There were no LOC 

exceedances for these three taxa. There was acute risk indicated to listed species and risks that 

could be mitigated by restricted use for estuarine/marine invertebrates from the proposed uses on 

ginseng and ornamentals. 

Chronic Risk Concerns: Chronic risks to freshwater fish and aquatic (freshwater and 

estuarine/marine) invertebrates were below the Agency’s chronic LOCs for all proposed uses of 

fenpyrazamine. Chronic risks to estuarine/marine fish could not be determined with precision 

due to a non-definitive NOAEC (< 39 ug a.i/L). Despite the lack of bonded estimation of 

chronic risk for estuarine/marine fish, (i.e., RQ values preceded by “>”) the LOC of 1 was 

exceeded for the proposed uses on ornamentals and ginseng. However there is uncertainty with 

this and the remaining chronic RQ values for estuarine/marine fish as it is not known how far 

above the estimated RQ that the actual RQ falls. A similar case exists with estuarine/marine 

invertebrates (NOAEC of 98 ug a.i/L). However in this case, the RQ would be preceded by “<” 

values to indicate that the estimated RQ is an “at most,” scenario. For both freshwater and 

estuarine/marine invertebrates, there were no exceedances of the chronic LOC for any of the 

proposed uses of fenpyrazamine.

Risks to Aquatic Plants: Based on the available data to one vascular and 4 non-vascular aquatic 

plant species, risks to aquatic plants are indicated for non-vascular plants but not for vascular 

plants. Toxicity data indicated that the most sensitive non-vascular aquatic plant was 2 orders of

magnitude more sensitive than vascular aquatic plants which led to the listed LOC being 

exceeded for all uses of fenpyrazamine and to non-listed LOCs being exceeded for all uses 

except almonds and pistachios for non-vascular plants. There were no non-listed or listed LOC 

exceedances for vascular aquatic plants for all proposed uses of fenpyrazamine. 

Risks to Benthic Invertebrates: Chronic data are available for 3 species of freshwater and 

estuarine/marine benthic invertebrates. However, the chronic RQs could not be estimated with 

precision due to non-definitive endpoints being reached for the most sensitive freshwater and 
7

estuarine/marine benthic invertebrate endpoints (NOAECs of <101 and <3000 μg a.i/kg 

sediment, respectively). Using the chronic LOC of 1 and the 1-in-10 year 21-day average EECs 

for risk estimation purposes, sediment RQs exceeded the LOC for freshwater benthic 

invertebrates for the proposed uses on ornamentals and ginseng. Corresponding pore water 

EECs also exceeded the LOC for the ornamental and ginseng uses. For estuarine/marine benthic 

invertebrates, there was no sediment or pore water RQs that exceeded the LOC. As was the case 

for chronic risk to estuarine/marine fish, there is uncertainty with these chronic RQ values as it is 

not known how far above the estimated RQ that the actual RQ falls. 

1.2.2 Terrestrial Animals and Plants

Acute Risks Concerns for Birds and Mammals: Acute dose-based risks for birds were 

indicated for small birds eating short grass for all proposed uses of fenpyrazamine. There were 

other LOC exceedances for additional food items and size class of organisms depending on the 

use. The acute high risk LOC of 0.5 was exceeded only in the case of small birds eating short 

grass for the ornamental use. Other LOC exceedances were the acute endangered species LOC 

(0.1) and the acute restricted use LOC (0.2). There were no acute dietary based exceedances for 

birds except a marginal exceedance of the acute endangered species LOC for dietary ingestion of 

short grass under the ornamental use. Acute dose-based risks for mammals indicated marginal 

exceedances of the acute endangered species LOC (0.1) for small and medium sized mammals 

ingesting short grass under the ornamental use. 

Chronic Risk Concerns for Birds and Mammals: A potential for chronic risks to birds and 

mammals was indicated in this assessment via dietary-based exposure. Exceedances of the 

chronic LOC of 1 were indicated for all proposed uses of fenpyrazamine except the uses on 

almonds and pistachios for at least one food item. Chronic dose-based RQs for mammals 

indicate exceedances of the LOC for small and medium sized mammals exposed to at least one 

food item for all proposed uses and exceedances for all three size classes for the ornamental use 

only. There were no chronic dietary-based RQ exceedances for any of the proposed uses. 

Risk Concerns for Terrestrial Plants: For almonds and pistachios, the acute LOC of 1 was 

exceeded for listed dicot species in semi aquatic areas. There were no other LOC exceedances 

for this use. For lettuce, grapes, bushberries, caneberries, strawberries, and ginseng, the acute 

LOC of 1 was exceeded for listed dicot species in semi aquatic areas with no other LOC 

exceedances. For the use on ornamentals, listed monocot species in semi aquatic areas and listed 

dicot areas in dry, semi aquatic, and areas resulting from spray drift all exceeded the acute LOC. 

Therefore, the potential for risk is indicated to these groups of terrestrial plants from the uses 

exceeding the LOC of 1. 

It is important to note that the RQs summarized in Table 32 did not have EC25 endpoints input 

into the TerrPlant model for vegetative vigor on account of a lack of a 25% or greater inhibition 

for all variables for these studies precluding that endpoint to be estimated. Furthermore, the 

NOAEC for seedling emergence for dicot species was a non-definitive endpoint (<0.035 lbs 

a.i/A). Additionally, the EC25 values for seedling emergence (monocot and dicot) were non 

definitive (>1.54 ad >0.53 for monocots and dicots, respectively). Therefore the RQs are not 
8

determined to be precise, and there exists uncertainty with these endpoints that arise from the use 

of non-definitive RQs. 

Risk Concerns for Beneficial Insects: Available toxicity data for fenpyrazamine indicate it is 

practically non-toxic to honeybee on an acute contact and an acute oral basis. While exposure

potential exists via pathways such as spray drift, limited data available show fenpyrazamine to be 

of limited toxicity to the honey bee. Additionally, an acute toxicity study to the earthworm 

indicated that survival ranged from 92.5 to 100%, depending on the treatment concentration. 

The LC50 was determined to be >800 mg a.i/kg dw soil and therefore the data (while limited) 

suggest fenpyrazamine to be of low toxicity to the earthworm.

1.3 Risk Characterization 

In characterizing the risk to terrestrial and aquatic organisms exposed to fenpyrazamine, the 

largest uncertainties in the currently submitted registrant data is the absence of environmentallyrelevant hydrolysis data at pH7 and availability of data in only one water-sediment system 

anaerobic aquatic metabolism study. . Therefore, to address these deficiencies, conservative 

assumptions are made within the PRZM/EXAMS model that lead to high estimates of the 1-in10 year 21-day and 60-day average EECs in water and sediment that are evidenced by relatively 

modest decreases from their peak values. This translates into more conservative estimates of 

chronic risk to aquatic organisms inhabiting both the water column and the benthic zone. The 

taxa that are implicated the most by these conservative estimates of chronic exposure are 

estuarine/marine fish and freshwater and estuarine/marine sediment invertebrates. Registrant 

submitted data for these three taxa yielded non-definitive (i.e. “<”) NOAECs and therefore the 

estimated RQ is only a lower bound estimate of risk (i.e. “>”). It is an uncertainty of how much 

higher than the estimated lower bound RQ that the actual unbounded RQ falls but more refined 

estimates of chronic exposure would likely mitigate some of this uncertainty by driving the 

current unbounded estimates of chronic risk further down away from the chronic LOC.

2. USE CHARACTERIZATION

V-10135 4 SC Fungicide (43.6 percent fenpyrazamine a.i., 56.4% inert ingredients) suspension 

concentrate is being proposed for aerial and ground foliar applications on almonds, grapes, 

lettuce, and strawberries for major food crop uses as well as on ornamentals (greenhouse and 

nursery) as the only major non-food crop use. Additional IR-4 minor crop uses are proposed for 

conventional ground and aerial foliar applications on pistachio, bushberry, caneberry, and 

ginseng crops. Proposed maximum application rates of fenpyrazamine range between 0.375 lbs. 

a.i./A – 1.089 lbs. a.i./A with three to four treatments, at a minimum of 7 seven days between 

applications specified on the proposed product label. Table 1 summarizes the labeling for the 

proposed uses of fenpyrazamine.
9

Table 1. Summary use information for fenpyrazamine, based on the proposed V-10135 4 

SC Fungicide suspension concentrate label by Valent U.S.A.

CROP USE

REGULATORY 

ACTION

MAX. SINGLE 

APP. RATE 

(lbs. a.i./A)

MAX. NUMBER OF 

APPS. and MIN. 

RETREATMENT 

INTERVAL

SEASONAL APP. 

RATE

(lbs. a.i./A) 5

APPLICATION

METHOD2

Almonds Sec. 3 0.375 3 apps., 7 days 

apart 1.125 G, A

Grapes

Sec. 3 0.5 3 apps., 7 days 

apart 1.5 G, A

Lettuce

Strawberries Sec. 3 0.5 4 apps., 7 days 

apart 2.0 G, A

Ornamentals Sec. 3 1.0891 3 apps., 7 days 

apart 3.267 G, A

Pistachios IR-4 0.375 3 apps., 7 days 

apart 1.125 G, A

Bushberries3

IR-4 0.5 3 apps., 7 days 

apart 1.5 G, A

Caneberries4

Ginseng IR-4 0.5 4 apps., 7 days 

apart 2.0 G, A

1. Maximum application rate based on a rate of 0.5lbs./100 gal specified on the label. According to the label, 100 

gallons of spray solution treats 20,000 square feet. Therefore, 0.5 lbs./20,000 ft.2is equivalent to 1.089 lbs./A.

2 Application method identifiers: G = Foliar ground spray/spray chemigation; A = Foliar Aerial Spray

3 Bushberries include aronia berry, blueberry, highbush and lowbush, buffalo currant, Chilean guava, cranberry, 

highbush, black currant, red currant, elderberry, European barberry, gooseberry, edible honeysuckle, huckleberry, 

jostaberry, juneberry, lingonberry, native currant, salal, sea buckthorn, and cultivars.

4 Caneberries include blackberry, logan berry, raspberry, wild raspberry, and cultivars.

5

Seasonal application rate specified on label except for ornamentals. Seasonal application rate for ornamentals

assumed based on maximum number or applications specified on label.

3. ENVIRONMENTAL FATE AND TRANSPORT

CHARACTERIZATION

Physical and chemical properties of fenpyrazamine are shown in Table 2 below. Environmental 

fate and transport properties of fenpyrazamine based upon registrant submitted studies or other 

references are shown in Table 3 below. Since fenpyrazamine is moderately mobile and soluble, 

fenpyrazamine applied to crops has the capability of being translocated to nearby water bodies 

via residues dissolving in runoff water. In addition, fenpyrazamine may also sorb to soil and 

therefore may reach nearby water bodies via erosion. Hydrolysis appears to mediate the overall 

degradation of fenpyrazamine in soil and water as it declines faster in alkaline environments 

rather than acidic environments.
10

Table 2. Physical and chemical properties of fenpyrazamine.

Property Value and units MRID or Source

Structure MRID 48399915

Chemical Class Pyrazole Carboxamide Fungicide http://www.alanwood.net

Chemical Formula C17H21N3O2S MRID 48399915

Molecular Weight 331.4 g/mol MRID 48399915

Vapor Pressure

(25°C) 2.17 x 10-10 torr MRID 48399916

Henry’s Law 

Constant 1 2.28 x 10-10 atm·m3

/mol EpiSuite 

HENRYWIN v. 3.20

Water Solubility

(pH 7, 20°C) 20.4 mg/L MRID 48399915

Octanol – water 

partition coefficient 

(log KOW)

3.52 MRID 48399914

Table 3. Summary of fenpyrazamine environmental fate properties.

Study/ 

OCSPP 

Guideline 

No.

Value and unit MRID # 

or 

Citation

Study Classification, 

Comment

Abiotic 

Hydrolysis

(835.2120)

pH4: Stable (Low levels of degradation observed)

pH7: Environmentally relevant half-lives could not be 

determined, but qualitative useful information was obtained.

pH9: 10.9 days

48399923

Supplemental

Data for pH7, 25°C not 

provided

Degradates observed: 

S-2188-OH at pH 4, 

pH7, and pH9; and S2188-DC at pH7 and 

pH9.

Aqueous 

Photolysis

(835.2240)

t 1⁄2 = 1.64 days (SFO)

pH 6.90 – 6.96 (neutral) 48399924

Acceptable

Environmentally 

relevant half-life, 

corrected for dark 

control

Complete formation 

and decline of 

degradates could not be 

established
11

Table 3. Summary of fenpyrazamine environmental fate properties.

Study/ 

OCSPP 

Guideline 

No.

Value and unit MRID # 

or 

Citation

Study Classification, 

Comment

Soil 

Photolysis

(835.2410)

UK SiL (alkaline, pH 6.9): t 1⁄2 81.05 days (SFO) 48399926

Supplemental

Data showing 

representativeness of 

foreign soil to domestic 

soil (e.g., taxonomic 

classification) not 

provided

Environmentally 

relevant half-life, 

corrected for dark 

control

Degradation 

in air

(835.2370)

Reaction with Hydroxyl Radicals

t 1⁄2 = 0.102 days

Reaction with Ozone

t 1⁄2 = 0.347 days

EpiSuite

AopWin 

v. 1.92

Estimated values

Aerobic 

Soil 

Metabolism

(835.4100)

UK SL (alkaline, pH 7.5): t 1⁄2 = 49.3 days (DFOP)

UK SL (acidic, pH 5.2): t 1⁄2 = 801 days (IORE)

UK L (alkaline, pH 7.9): t 1⁄2 = 37.7 days (IORE)

UK SiL (acidic, pH 6.9): t 1⁄2 = 230 days (DFOP)

NJ SiL (acidic, pH 6.3): t 1⁄2 = 201 days (IORE)

48399920

48399927

Supplemental

Data showing 

representativeness of 

foreign soil to domestic 

soil (e.g., taxonomic 

classification) not 

provided

Supplemental

Soil moisture levels 

throughout study not 

reported

Anaerobic 

Soil 

Metabolism

(835.4200)

NJ SiL (acidic, pH 6.8): t 1⁄2 = 128 days (SFO) 48399928

Acceptable

Complete formation 

and decline of 

degradates could not be 

established
12

Table 3. Summary of fenpyrazamine environmental fate properties.

Study/ 

OCSPP 

Guideline 

No.

Value and unit MRID # 

or 

Citation

Study Classification, 

Comment

Aerobic 

Aquatic 

Metabolism

(835.4300)

UK Silty Clay Loam Sediment: t 1⁄2 = 18.9 days (SFO)

(alkaline water pH7.3 – 8.0, acidic sediment pH 6.5 – 6.6 )

Swiss Lake Sand Sediment: : t 1⁄2 = 280 days (IORE)

(acidic water pH 6.0 – 6.36, alkaline sediment pH 7.5)

48399929

Acceptable

4

pH initial values in 

study

Complete formation 

and decline of 

degradates could not be 

established

Anaerobic 

Aquatic 

Metabolism

(835.4400)

MS Clay Sediment: t 1⁄2 = 12.2 days (SFO)

(alkaline water, pH 8.3, acidic sediment pH 6.9,

48399930

Acceptable5

pH initial values in 

study

Complete formation 

and decline of 

degradates could not be 

established

Mobility, 

unaged 

leaching, 

adsorption/

desorption 

(835.1220)

UK CL: Koc = 250 mL/g; Kd = 8.7 mL/g; 

OC = 4.8%; pH8.0

UK SiL: Koc = 343 mL/g; Kd = 7.4 mL/g; 

OC = 2.7%; pH7.0

UK L: Koc = 123 mL/g; Kd = 4.2 mL/g; 

OC = 3.8%; pH6.0

UK LS: Koc = 766 mL/g; Kd = 5.7 mL/g ; 

OC = 0.8 %; pH5.1

Japan SL: Koc =269 mL/g; Kd = 6.6 mL/g ; 

OC = 3.2 %; pH5.9

NJ SiL: Koc = 366 mL/g; Kd = 3.5 mL/g ; 

OC = 1.4%; pH6.3 

CA LS: Koc = 585 mL/g; Kd = 0.87 mL/g ; 

OC = 0.2%; pH7.5

48399919

48399922

Supplemental

Data showing 

representativeness of 

foreign soil to domestic 

soil (e.g., taxonomic 

classification) not 

provided

Supplemental

Only 4 test 

concentrations used in 

study

Terrestrial 

Field 

Dissipation

(835.6100)

CA SL (neutral, pH 6.4 – 7.1): t 1⁄2 = 9.68 days (IORE)

CA LS (neutral, pH 5.7 -7.3): t 1⁄2 = 7.68 days (IORE)

ID L (neutral, pH 6.7 – 7.7): t 1⁄2 = 7.30 days (IORE)

NY S (neutral, pH 6.4 – 6.7): t 1⁄2 = 24.3 days (IORE)

48399931

48399932

48399933

48399934

Acceptable

Acceptable

Acceptable

Acceptable
13

Table 3. Summary of fenpyrazamine environmental fate properties.

Study/ 

OCSPP 

Guideline 

No.

Value and unit MRID # 

or 

Citation

Study Classification, 

Comment

Fish 

Bioconcen

-tration 

Factor 

(BCF)

(850.1730)

Bluegill Sunfish Edible Tissues

Steady State BCF = 7 L/kg

Fenpyrazamine accounted for <1 percent of total radioactive 

residues after a depuration period of 14 days.

Bluegill Sunfish Non-Edible Tissues

Steady State BCF = 10 L/kg

Fenpyrazamine accounted for <1 percent of total radioactive 

residues during depuration phase.

Bluegill Sunfish Whole Fish Tissues

Steady State BCF = 9 L/kg

Fenpyrazamine accounted for <1 percent of total radioactive 

residues during depuration phase.

48400005 Acceptable

Env.

Chemistry

Method

(ECM)

Water (Tap and Pond)

Mean Recoveries 85 – 93%; RSD 4 - 11

Water (Well)

Mean Recoveries 81.2 – 102%; RSD 3.53 – 18.8

Soil

Mean Recoveries: 87%; RSD 2.3 – 2.9

48399918

48400034

48400026

Acceptable

Independent

Laboratory

Validation

(ILV)

Water (Well)

Mean Recoveries 103 – 94.6%; RSD 2.34 – 2.62

Soil

Mean Recoveries: 89.4% -90.9%; RSD 6.5 – 8.4

48400034

48400026

Acceptable

Storage 

Stability

Soil

Normalized/Corrected Mean Recovery:

100 – 122.1 percent (Days 0 – 366)

48399921 Acceptable

1 NA means not applicable.

2 Half life degradation kinetics scheme determinations:

SFO = Single First Order, IORE = Indeterminate Order Rate Equation, DFOP = Double First Order in Parallel

Kinetic models and representative half-lives were determined in agreement with the “Guidance for Evaluating and 

Calculating Degradation Kinetics in Environmental Media” (2011), accessed 09/27/12 at 

http://www.epa.gov/oppfead1/international/naftatwg/guidance/guidance.htm .

3 Soil textural classifications:

S: Sand

SL: Sandy Loam

LS: Loamy Sand

SiL: Silt Loam

L: Loam

CL: Clay Loam 

4 Although the study is acceptable, there are still uncertainties related to the variations in biodegradation versus 

possible mediation from hydrolysis that is evident from the data. Please refer to the uncertainties and limitations

section at the end of this chapter, Section 7.2.6.b, and Section 8 for further details.
14

5 Although the study is acceptable, there is still a data gap since only one water-sediment system was evaluated. 

Please refer to the uncertainties and limitations section at the end of this chapter, Section 7.2.6.b, and Section 8

for further details.

 Fenpyrazamine Mobility and Transport to Water Bodies

Given foliar applications of fenpyrazamine, residues may be deposited into soil via washoff from 

rainfall or irrigation activities as well as directly deposited onto soil during the application. 

Fenpyrazamine may reach surface water bodies or ground water given its solubility of 20.4 mg/L 

at 20°C (indicating that fenpyrazamine is highly soluble) (MRID No. 48399915) and Kd values 

ranging between 0.87 –8.7 mL/g (indicating that fenpyrazamine is slightly to moderately mobile

in soil)(MRID Nos. 48399919 and 48399922).3It appears that sorption of fenpyrazamine is not 

well correlated to organic carbon content given the weak relationship between soil-water 

partition coefficients and organic carbon content collectively among soils. Fenpyrazamine’s 

properties are common to other pesticides that are known to dissolve in runoff water to reach 

surface water bodies and leach to ground water. Furthermore, fenpyrazamine residues may also 

reach surface water bodies via erosion as its range of Kd values suggests that residues may bind 

to soil particles to a certain extent. Fenpyrazamine is not expected to escape from dry or moist 

soil surfaces or water bodies to the air via volatilization given its low vapor pressure value of 

2.17 x 10-10 torr (at 25°C) (MRID No. 4833906) and low Henry’s Law Constant of 2.28 x 10-10

atm·m3/mol (at 25°C) (EpiSuite HENRYWIN v. 3.20).

 Degradation of Fenpyrazamine (S-2188) and Identification of Transformation 

Products in Soil 

Fenpyrazamine appears to be moderately persistent in alkaline soil environments. Aerobic soil 

metabolism4half-lives range between 37.7 and 49.3 days, respectively under alkaline conditions 

(MRID No. 48399920). Although no sterile controls were included, it is expected that the 

biodegradation is supplemented by hydrolysis in alkaline environments. These half-lives are 

most similar to the decline (e.g., runoff, leaching, and biodegradation) of fenpyrazamine 

observed in terrestrial field dissipation studies conducted in neutral soils in California (2 sites), 

Idaho (1 site), and New York (1 site) with total soil profile (including depths below the runoff 

extraction zone) half lives observed between 7.3 and 24.1 days (MRID Nos. 48399931, 

48399932, 48399933, and 48399934). Fenpyrazamine appears to be persistent in acidic soils 

with half-lives between 201 – 801 days as observed in aerobic soil metabolism studies (MRID 

Nos. 48399920, and 48399927)5 In anaerobic acidic soil environments, half-lives are a little less 

 

3 Kd values determined from seven soils encompassing NJ Silt Loam, CA Loamy Sand soils from MRID No. 

48399922 and UK Clay Loam, UK Silt Loam , UK Loam, and UK Loamy Sand, and Japan Sandy Loam from 

MRID No. 48399919. . No information was provided indicating the representativeness of foreign soils to domestic 

soils. Please refer to Uncertainties and Limitations section.

4 Alkaline soils in aerobic soil metabolism studies analyzed include UK Sandy Loam Soil (PT-102) and UK Loam 

Soil (SK920191) in MRID No. 48399920. No information was provided indicating the representativeness of foreign 

soils to domestic soils. Please refer to Uncertainties and Limitations section.

5 Acidic soils in aerobic soil metabolism studies analyzed include UK Sandy Loam Soil (PT-103) and UK Silt Loam 

Soil (SK1556090) in MRID No. 48399920 as well as NJ Silt Loam Soil in MRID No. 48399927. . No information 

was provided indicating the representativeness of foreign soils to domestic soils. Please refer to Uncertainties and 

Limitations section.
15

at 128 days in NJ Silt Loam Soil (MRID No. 48399928). There are no studies available for 

anaerobic soil alkaline environments. There are also no field dissipation studies conducted in 

acidic environments. Soil photolysis appears to be a minor degradation pathway with a half-life 

of 104 day in NJ Silt Loam Soil (MRID No. 48399926).

In alkaline aerobic soil metabolism studies (MRID No. 48399920) 5, the degradate S-2188-OH

forms at levels of between 0.8 percent – 2.7 percent of applied radioactivity (See Appendix F for 

a more detailed summarization of the degradates formed, their structures and at what percentages 

result). For alkaline conditions, the degradate S-2188-DC forms at levels between 0.5 – 2.8 

percent of applied radioactivity in aerobic soil metabolism studies (MRID Nos. 48399920 and 

48399923). In general, degradates were not observed to form to significant levels in the aerobic 

soil metabolism studies. The likely mechanism of dissipation is due to incorporation into soil 

organic matter as evidenced by large levels of unextracted residues, accounting for 

approximately up to 70 percent of the material balance in two alkaline soils in aerobic soil 

metabolism studies (MRID No. 48399920)5,6. The identity of the unextracted residues (whether 

they consist of parent or metabolite residues) is not certain since both parent and degradates are 

moderately mobile as evident from partition coefficients shown ahead in Table 4. Furthermore, 

the Koc values of degradates range between 123 – 1,704 mL/g, indicating a moderate tendency

for residues to partition to soil much like fenpyrazamine. It is not expected that unextracted 

residues incorporated in eroded soil layers which become sediment in water bodies will desorb 

into the water column as demonstrated by the exhaustive extraction procedures used in the 

laboratory studies. This tendency has also been observed in the batch equilibrium studies 

(MRID No. 48399919) as less than 32 percent of residues were observed to desorb into the water 

column for all soils evaluated.

Based upon the information described above from the environmental fate laboratory studies, the 

degradation pathway for the terrestrial (soil) environment is presented in Figure 1 below.

Figure 1. Proposed degradation and dissipation pathways in soil.

 

6 Thorough extraction of bound residues was attempted using multiple solvents and repetitions adequately 

demonstrated that residues became tightly incorporated into soil and sediment particles.

Incorporated Residues

to Soil Layer
16

 Degradation of Fenpyrazamine (S-2188) and Identification of Transformation 

Products in Water

Upon reaching water bodies, aqueous photolysis is expected to be the main degradation 

mechanism for fenpyrazamine in reservoir surface waters, with a half-life of 1.64 days (corrected 

for environmentally relevant conditions). The degradates S-2188-DC and MCNI formed to 

significant levels of 65.6 and 19.9 percent of the applied, respectively. Hydrolysis is also 

expected to be a key degradation pathway particularly in alkaline environments. However, some 

degradation is evident in acidic, neutral, and alkaline environments with formation of the 

degradate S-2188-OH observed at pH4, pH7, and pH9; and S-2188-DC observed at pH7 and 

pH9. An environmentally relevant hydrolysis half-lives of 10.9 days has been determined at 

pH9. Fenpyrazamine is stable at pH4, although a very small amount of the degradate S-2188-

OH was detected. No environmentally relevant half-life at pH7 is available. This deficiency is

described in Table 3 and in the Uncertainties and Limitations section before the conclusion of 

this chapter.

Fenpyrazamine degrades at a moderate rate in aerobic alkaline environments with a half life of 

18.9 days as indicated in an alkaline aerobic aquatic metabolism study for the Calwich Abbey, 

UK lake water- silty clay loam sediment system (MRID No. 48399929). Although no sterile

controls were included, it is expected that the biodegradation is supplemented by hydrolysis in 

alkaline environments. In aerobic aquatic acidic environments, fenpyrazamine degrades much 

slower with a half life of 280 days in a Swiss lake – sand sediment system (MRID No. 

48399929). In anaerobic acidic aquatic environments, fenpyrazamine is moderately persistent

with a half-life of 12.2 days in a Mississippi Creek –clay sediment system (MRID No. 

48399930). 

In aerobic alkaline aquatic environments, the S-2188-OH and S-2188-DC degradates form in 

significant quantities encompassing up to 17.3 and 23.5 percent of the applied, respectively, in 

the Calwich Abbey, UK Lake – silty clay loam sediment system (MRID No. 48399929). Like 

for aerobic soils, there are significant quantities of unextractable residues observed. Unextracted 

residues in the Calwich Abbey, UK lake-silty clay loam sediment system accounted for up to 

48.4 percent of the applied. Therefore, the unidentified unextracted residues accounted for in 

aerobic aquatic metabolism studies for alkaline systems may comprise of additional levels of 

fenpyrazamine, S-2188-OH, and S-2188-DC degradates. Likewise from soil, it is not expected 

that these residues will be bioavailable in the aquatic compartment of water bodies since residues 

remained incorporated in sediment after exhaustive extraction techniques in the study were 

employed. 

Based upon the information described above from the environmental fate laboratory studies, the 

degradation pathway for aquatic environment is presented in Figure 2 below.
17

Incorporated Residues to Sediment Layer

.

Figure 2. Proposed degradation and dissipation pathways in water.

 Bioconcentration of Fenpyrazamine and Degradate Residues in Fish

Steady-state BCF values in fish between 7 -10 L/kg from edible tissues, non-edible tissues, and 

whole fish indicate that bioaccumulation potential of fenpyrazamine residues is low (MRID No. 

48400005)7. In addition, depuration of fenpyrazamine is negligible and fish tissue metabolism is 

high, since in the uptake phase, fenpyrazamine is transformed rapidly to S-2188-DC and S-2188-

DC conjugate. In the depuration phase, the major degradates that remained in edible fish tissue 

included S-2188-DC and the S-2188-DC conjugate which existed at maximum levels of 16.2 

percent and 42 percent of total radioactive residues, respectively. The depuration rates are rapid 

among the degradates. The depuration half-life of the S-2188-DC degradate is 1.74 days and the 

S-2188-DC Conjugate is 10.1 days (MRID No. 48400005)7. Therefore, given the high 

metabolism of fenpyrazamine evident in fish and high depuration rates of the degradates, 

bioaccumulation in fish resulting from fenpyrazamine pesticide applications is not a concern. 

 Fate and Transport Characteristics of Transformation Products

The formation of all fenpyrazamine degradates in soil and water which form due to abiotic 

processes and biodegradation is shown in Appendix F. The properties of the degradates of

fenpyrazamine which form in soil and water are shown in Table 4 below. Fenpyrazamine 

appears to be less mobile than its degradates as it is less soluble. However, despite this 

difference, fenpyrazamine and its degradates all possess solubility values in the same range of 

 

7 BCF study conducted on bluegill sunfish.
18

pesticides which both dissolve in runoff water and partition to soils and sediments. In addition, 

the log Koc values of degradates range between 2.20 – 3.67 indicating that they are slightly to 

moderately mobile based on the FAO classification scheme. The Kd values of fenpyrazamine 

between 3.5 mL/g – 8.7 mL/g (with one soil with a Kd value of 0.87 mL/g, see Table 3) further 

suggests that fenpyrazamine possesses mobility characteristics corresponding to the lower end of 

the range of that encompassing the degradates. Fenpyrazamine’s Koc values is not a valid model 

for comparison since its sorption is not highly correlated with organic carbon content.

Table 4. Comparison of physical chemical properties of fenpyrazamine transformation 

products to parent fenpyrazamine.

Property/

EPISuite 

Estimator 

Program

Value from

Product 

Chemistry EpiSuite Estimated Value

Fenpyrazamine

(S-2188) S-2188-OH S-2188-DC

S-2188-

DTC MCNI MPZZ

Molecular Weight 331.4 g/mol 247.3 g/mol 231.3 g/mol 271.4 g/mol 216.3 g/mol 189.2 g/mol

Solubility in Water 

(25 °C)

(WSKOWWIN v. 

1.42)

20.4 mg/La5,019 mg/L 938.2 mg/L 1,437 mg/L 107.7 mg/L 246,400 

mg/L

Vapor Pressure 

(25 °C)

(MPBPVP v. 1.43) 2.17 x 10-10 torrb 2.66 x 10-7

torr

2.87 x 10-7

torr

8.85 x 10-8

torr

6.23 x 10-7

torr

3.75 X 10-6

torr

Henry’s Law 

Constant (25 °C)

(HENRYWIN v. 

3.20)

2.28 x 10-10

atm·m

3

/molc

7.30 x 10-13

atm·m

3

/molc

9.31 x 10-11 

atm·m

3

/molc

2.20 x 10-11

atm·m

3

/molc

1.65 x 10-9

atm·m

3

/molc

4.23x 10-10

atm·m

3

/molc

Octanol-Water 

Partition Coefficient 

(Log Kow)

(WSKOWWIN v. 

1.42)

3.52d0.81 0.23 1.28 2.65 0.38

Soil-Water Partition 

Coefficient (Koc)

(KOCWIN v. 2.00)

N/Ae158.6 mL/g 1,302 mL/g 4,633 mL/g 428.1 mL/g 1,704 mL/g

*Only degradates found in environmental fate laboratory and field studies in soil and water are shown in table.

a

 Value at 20°C from MRID No. 4839915.

b

 From MRID No. 48399916.

c

 From EpiSuite HENRYWIN v. 3.20.

d

 From MRID No. 48399914.

e N/A means not available since Koc is not a good measure or sorption to soil or sediment..

The degradation half-lives of the transformation products for fenpyrazamine cannot be 

determined at this time based on the existing data from laboratory studies (see Table 3 for 

further information). The durations of environmental fate studies were insufficient to determine 

the complete formation and decline rates of the degradates which are needed to complete this 

analysis. This information has not been found upon inspection of open literature nor have data 

been identified among common degradates from existing active ingredients. However, the 

maximum formations of degradates detected in environmental fate laboratory and field studies 

can be found in Appendix F..
19

 Uncertainties and Limitations

There are several significant uncertainties with the environmental fate profile of fenpyrazamine. 

The first major uncertainty concerns fenpyrazamine’s rate of hydrolysis in the environment. The 

existing hydrolysis study suggests that fenpyrazamine degrades over all environments, especially 

in alkaline environments, with metabolites S-2188-OH and S-2188-DC detected (MRID No. 

48399923). This is also evident from the aerobic aquatic metabolism study (MRID No. 

48399929), which also shows a trend of decreased half-lives at higher pHs, suggesting that 

hydrolysis mediates degradation in alkaline environments. However, environmentally relevant 

hydrolysis data at 25°C were not provided to the Agency for neutral environments (pH7), 

including the rate of degradation as well as the levels of the transformation products for

fenpyrazamine. Additional hydrolysis information would confirm the rate of degradation, as 

well as the levels of the transformation products of fenpyrazamine at pH7 and 25°C at 

environmentally relevant conditions.

A second significant uncertainty relates to the limited sediment - water systems evaluated in the 

anaerobic aquatic study (MRID No. 48399930). Only one system was evaluated in each study. 

Additional water – sediment systems would provide a sufficiently robust dataset showing the 

distribution of microbial degradation. 

A third uncertainty regards unextracted residues incorporated in soil or sediment layers. In soil,

unextracted residues accounted for approximately up to 70 percent of applied in two alkaline 

soils in aerobic soil metabolism studies (MRID No. 48399920). In water, unextracted residues in 

sediment from the Calwich Abbey, UK study sample accounted for up to 48.4 percent of applied. 

It should be noted that unextracted residues are likely bonded chemically to the humin matrices 

within the soil and sediment layers. Soil-water partition coefficients of fenpyrazamine and 

degradates as well as inconsistencies in the amount of unextracted residues between the aerobic 

and anaerobic aquatic metabolism studies suggest that unextracted residues are not forming due 

to sorbtion of fenpyrazamine.

A fourth uncertainty which exists is that water-sediment systems with variable pHs were 

evaluated in the aerobic aquatic metabolism study. Since degradation is much different between 

acidic and alkaline conditions, it appears that degradation is mediated pH. 

The fifth uncertainty concerns the little availability of batch equilibrium studies conducted on 

domestically representative soils. The organic-carbon normalized partition coefficient (Koc) were 

only examined for a loamy sand soil from California and a silt loam soil from New Jersey

(MRID No. 48399922). The remaining soils were evaluated from the UK and Japan (MRID No. 

48399919). The UK soils are traditionally similar to the physical and chemical composition of 

soils in the United States. However, soils in Japan traditionally possess volcanic elements which 

are found over very limited areas in the United States. However, data that are available for five 

other foreign soils in the UK appear to confirm the moderate mobility of fenpyrazamine 

observed in the domestic soils. Additional information on the taxonomic properties of the

foreign soils would confirm their representativeness to US soils.
20

4. ECOLOGICAL TOXICITY CHARACTERIZATION

4.1 Receptors

Ecological measures of effect for this screening level risk assessment are based on a suite of 

registrant-submitted toxicity studies performed on a limited number of organisms in broad 

groupings. Table 5 gives examples of taxonomic groups and test species evaluated for 

ecological effects in this screening level risk assessment. Within each of these very broad 

taxonomic groups, an acute and/or chronic endpoint is selected from the available test data (see

Table 6). 

Table 5. Taxonomic groups and test species evaluated for ecological effects in this 

screening-level risk assessment

Taxonomic group Representative species

Birds a Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Canary (Serenris canaria)

Mammals Laboratory rat (Rattus norvegicus)

Terrestrial Invertebrates Honey bee (Apis mellifera)

Earthworm (Eisenia fetida)

Freshwater fish b Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Freshwater Invertebrates Water flea (Daphnia magna)

Estuarine/marine Fish Sheepshead minnow (Cyprinodon variegatus)

Estuarine/marine Invertebrates Mysid shrimp (Americamysis bahia), Eastern oyster 

(Crassostrea virginica)

Benthic Freshwater Invertebrates Amphipod (Hyalella azteca)

Freshwater midge (Chironomus riparius)

Benthic Estuarine/Marine Invertebrates Amphipod (Leptocheirus plumulosus)

Aquatic Plants and Algae Duckweed (Lemna gibba)

Green algae (Pseudokirchneriella subcapitata)

Marine diatom (Skeletonema costatum)

Freshwater diatom (Navicula pelliculosa)

Cyanobacteria (Anabaena flos-aquae)

Terrestrial Plants Multiple species

a Birds may be surrogates for amphibians (terrestrial phase) and reptiles.

b

Freshwater fish may be surrogates for aquatic phase amphibians.

For screening risk assessments, the following toxicity endpoints presented in Table 6 are used 

as inputs to the risk quotient (RQ) method for expressing risk (US EPA, 2004). Details of the 

risk quotient method and its associated LOCs are found in Appendix A. The designation of 

“listed species” refers to either federally threatened or endangered species.
21

Table 6. Toxicity endpoints used in risk quotient calculations.

Taxonomic group Representative species

Aquatic Animals

Acute assessment 

Chronic assessment 

Lowest tested EC50 or LC50 for freshwater fish and invertebrates and 

estuarine/marine fish and invertebrates acute toxicity tests.

Lowest no-observed-adverse-effects- concentration (NOAEC) for 

freshwater fish and invertebrates and estuarine/marine fish and 

invertebrates early life-stage tests.

Terrestrial Animals 

Acute avian assessment 

Chronic avian assessment 

Acute mammalian assessment 

Chronic mammalian assessment 

Lowest LD50 (single oral dose) and LC50 (subacute dietary).

Lowest NOAEC for 21-week avian reproduction test.

Lowest LD50 from single oral dose test. 

Lowest NOAEC for two-generation reproduction test or chronic dietary 

study

Plants

Terrestrial non-listed species 

Aquatic vascular and algae

Terrestrial listed species 

Lowest EC25 values from both seedling emergence and vegetative vigor for 

both monocots and dicots. 

Lowest EC50 for both aquatic vascular plants and algae.

Lowest EC05 or NOAEC for both seedling emergence and vegetative vigor 

for both monocots and dicots. 

a

Freshwater fish may be surrogates for amphibians (aquatic phase).

b Birds may be surrogates for amphibians (terrestrial phase) and reptiles.

Acute and chronic laboratory and field tests on fenpyrazamine on aquatic organisms provide 

information regarding lethality, as well as sublethal measures of effect. Data are available on the 

technical grade active ingredient (TGAI) and the effects on freshwater and estuarine/marine fish

and invertebrates, aquatic vascular and nonvascular plants (algae), and freshwater and 

estuarine/marine sediment dwelling organisms. Additionally acute toxicity data were available 

for certain degradation/transformation products of fenpyrazamine on rainbow trout, daphnia 

magna, and freshwater green algae. These studies will be discussed with the other toxicity data 

in Section 4.4 of this assessment.

For terrestrial effects, registrant-submitted studies on fenpyrazamine technical are available for 

acute, subacute dietary, and chronic exposure to birds, and acute and chronic exposure to 

mammals. Additional ecological effects data for fenpyrazamine are available for honey bees and 

earthworms. Finally, data on the effects of seedling emergence and vegetative vigor for ten 

species were submitted in support of fenpyrazamine. 

4.2 Ecosystems at Risk 

The ecosystems at potential risk from the proposed uses of fenpyrazamine are extensive in scope 

due to the wide geographic distribution of potential fenpyrazamine application sites. In general, 
22

terrestrial ecosystems potentially at risk could include the treatment areas directly and adjacent 

areas that may receive spray drift and/or runoff. This could include the treatment area itself as 

well as other cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, 

woodlands, riparian habitats and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to (or downstream from) the 

treatment area and might include impounded bodies such as ponds, lakes, reservoirs and wetland 

areas, or flowing waterways such as streams and rivers. For uses in coastal areas, aquatic habitat 

also includes marine ecosystems, including estuaries and salt marshes. Additionally freshwater 

and estuarine/marine benthic zones are at potential risk due to fenpyrazamine’s moderate 

persistence and mobility suggesting its potential to translocate and reside in water bodies.

4.3 Assessment Endpoints 

Assessment endpoints represent the actual environmental value that is to be protected, defined by

an ecological entity (species, community, or other entity) and its attribute or characteristics (US 

EPA, 1998). For the proposed fenpyrazamine uses, the ecological entities may include the 

following: birds, mammals, freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates (pelagic and benthic dwelling), insects, and aquatic and terrestrial plants. The 

attributes for each of these entities may include growth, reproduction, survival, biomass 

(standing crop for plants). For both aquatic and terrestrial animal species, direct acute and direct 

chronic effects are considered. Although these endpoints are measured at the individual level, 

they provide insight about risks at higher levels of biological organization (such as populations 

and communities). 

4.4 Ecological Effects Characterization 

The effects of fenpyrazamine on aquatic and terrestrial organisms as derived from laboratory 

studies are summarized in this section. It is important to recognize that the toxicity test results 

reported herein represent a small fraction of avian, mammalian, aquatic organisms and plant 

species resident to North America. Specifically, only a few surrogate species for both freshwater 

fish and birds are used to represent all freshwater fish (2000+) and bird (680+) species in the 

United States. For mammals, acute studies are usually limited to Norway rat or the house 

mouse. Estuarine/marine testing is usually limited to a crustacean, a mollusk, and a fish. Also, 

neither reptiles nor amphibians are commonly tested. In the absence of toxicity data for reptiles 

and terrestrial phase amphibians, this risk assessment uses the sensitivity of birds as a surrogate 

for terrestrial-phase amphibians and reptiles. Similarly, freshwater fish are used as a surrogate 

for aquatic-phase amphibians. 

In general, categories of acute toxicity ranging from “practically nontoxic” to “very highly toxic” 

have been established for aquatic organisms (based on LC50 and EC50 values or limit of 

solubility), mammals (based on LD50 values), avian species (based on LD50 and LC50 values), 

and non-target insects (based on LD50 values for honey bees) (U.S. EPA 2001). 
23

4.4.1 Aquatic Effects 

The acute and chronic toxicity values associated with freshwater and estuarine/marine species 

exposure to fenpyrazamine are summarized in Table 7. Toxicity endpoints shown in bold 

represent the most sensitive endpoints within a taxonomic grouping (e.g., freshwater fish, 

freshwater invertebrates, aquatic plants, etc.). These endpoints are termed the “toxicity reference 

values” which are used for this quantitative risk assessment. All acute, chronic, and subchronic 

exposures to animals as well as exposures to plants are expected given fenpyrazamine’s 

moderate persistence and mobility suggesting its potential to translocate and reside in water 

bodies. Studies that were submitted with various degradation products of parent fenpyrazamine 

are summarized in Table 8.

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Freshwater Fish

Acute

TGAI

94.7%

Rainbow Trout

Oncorhynchus mykiss

96 h LC50 = 5.2 mg 

a.i./L (3.8 – 7.8)

Probit Slope = 

N/A

 100% mortality was observed 

in the highest treatment 

concentration (7.8 mg a.i/L, 

mean measured).

 5% or less mortality was 

observed in the controls and 

remaining treatment 

concentrations

 Varying number of fish in the 

three highest treatment 

concentrations (2.1, 3.8, and 

7.8 mg a.i/L, mean measured) 

were lethargic

48399945

Acceptable

(2006)

Acute

TGAI

94.7%

Bluegill sunfish 

(Lepomis macrochirus)

96 h LC50 = 5.4 mg 

ai/L (3.4 – 6.9)

Probit Slope = 

N/A

 There was 85 and 100% 

mortality in the two highest 

treatment concentrations (6.9 

and 12 mg a.i/L mean 

measured, respectively)

 0% mortality occurred in the 

controls and all other treatment 

concentrations (0.88, 1.8, and 

3.4 mg a.i/L)

 All fish in highest treatment 

group exhibited a complete 

loss of equilibrium after three 

hours of exposure and were 

dead by six hours

48399944 

Acceptable

(2006)
24

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Chronic

TGAI

94.7%

Rainbow Trout

(Oncorhynchus 

mykiss)

90 d NOAEC 

(survival at 

hatch, survival 

at test 

termination) = 

370 μg a.i./L

LOAEC = 750 μg 

a.i./L

 Embryo viability averaged 62 –

70% across the controls and all 

treatment concentrations 

 Day-0 post hatch survival of 

larvae ranged from 96 – 100% 

across the controls and all 

treatment concentrations

 Day-60 post hatch survival was 

significantly reduced at the 

highest treatment concentration

 Total length, wet weight, and 

dry weight were not 

significantly reduced at any 

treatment level (highest 

treatment level excluded from 

analysis due to effects on 

survival)





48400003

Acceptable

(2006)

Freshwater Invertebrates

Acute

TGAI

94.7%

Water flea

Daphnia magna

48 h EC50 = 5.5 mg 

a.i/L (4.6 – 6.5)

Probit Slope: 

10.2 (6.1 – 14.2)

 0% mortality in negative and 

solvent control as well as three 

lowest treatment groups

 95% mortality at highest 

treatment group (8.0 mg a.i/L) 

 Lethargy among surviving 

daphnids observed in all 

treatment groups

48399939

Acceptable

(2006)
25

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Chronic

TGAI

94.7%

Water flea

Daphnia magna

21 d NOAEC: 0.34 

mg a.i/L

LOAEC: 0.76 mg 

a.i/L

 There were no treatment 

related effects on survival

 Number of offspring released 

by females was significantly 

reduced (p<0.05) at the two 

highest treatment 

concentrations (0.76 and 1.4 

mg a.i/L, mean measured)

 Body lengths of surviving 

daphnid were significantly 

reduced (p<0.05) at the two 

highest treatment 

concentrations

 Dry weights of surviving 

daphnids were statistically 

reduced (p<0.05) at the highest 

treatment concentration only

 There was a delayed time to 

first brood compared to the 

controls at the two highest 

treatment concentrations (Day 

9 at 0.76 mg a.i/L, Day 10 at 

1.4 mg a.i/L, compared to Day 

7 for controls and all other 

treatment concentrations

 Immobilized offspring, if any, 

were not reported

48400001

Acceptable

(2006)

Estuarine/Marine Fish

Acute

TGAI

98.8%

Sheepshead minnow

(Cyprinodon 

variegatus)

96 h LC50: >3.9 mg 

ai/L (95% CI 

N/A)

Probit Slope: N/A

 20% mortality occurred in the 

3.9 mg a.i/L treatment 

concentration (mean 

measured), the highest 

treatment concentration

 There was no mortality in the 

negative control or any other 

treatment concentration

 There were no clinical signs of 

toxicity or sublethal effects 

observed in the negative 

control or any treatment 

concentrations except the 

highest in which several 

surviving fish were lethargic, 

and two surviving fish 

exhibited a partial loss of 

equilibrium.

48399946

Acceptable

(2010)
26

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Chronic TGAI 

98.8% Sheepshead minnow

(Cyprinodon 

variegatus)

33 d NOAEC (length) 

= <0.039 mg 

a.i/L

LOAEC (length) 

= 0.039 mg a.i/L

 No treatment-related effects on 

hatching success or post hatch 

larval survival were observed

 Statistically significant 

(p<0.05) effects on length 

observed at all treatment 

concentrations

 Dry weight effects were 

statistically significant (P,0.05) 

at the two highest treatment 

concentrations (0.58 and 1.2 

mg a.i/L)

 Time to hatch and clinical 

signs of toxicity (if any) were 

not reported

48400004

Supplemental

(2010)

Estuarine/Marine Invertebrates

Acute

TGAI

98.8%

Saltwater mysid 

(Americamysis bahia)

96 h LC50 = 0.83 mg 

ai/L (0.62 – 1.2)

Probit Slope: N/A

 100% mortality occurred at 

three highest treatment 

concentrations (1.2, 2.3, and 

4.6 mg a.i/L, mean measured)

 All mysids in the control and 

lowest treatment concentration 

(0.29 mg a.i/L, mean 

measured) appeared normal 

and healthy throughout the 

study

48399941

Acceptable

(2010)

TGAI

98.8%

Eastern Oyster 

(Crassostrea virginica)

96 h EC50 = 0.78 mg 

ai/L (0.58 – 1.1 

mg ai/L)

NOAEC= 0.49 

mg ai/L

 Shell growth was reduced by 

30.4, 21.7, 21.7, 30.4, and 73.9 

relative to controls at 0.066, 

0.12, 0.24, 0.49, and 1.0 mg 

ai/L, respectively (mean 

measured).

48399940

Acceptable

(2010)
27

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Chronic

TGAI

98.8%

Saltwater mysid 

(Americamysis bahia)

38 d NOAEC = 98 μg 

a.i./L 

LOAEC50 = > 98 

μg a.i./L 

 Mysids exposed to control, 3.2, 

6.8, 13, 24, 47, and 98 μg a.i/L 

mean measured treatment 

concentrations

 There were no significant 

reductions (p<0.05) for time to 

first brood release, F0 survival, 

F1 survival, male and female 

dry weight, and male total 

body length

 While there was a significant 

reduction at the lowest 

treatment concentration for 

number of offspring per 

female, this was the only 

treatment concentration 

affected

 Female total body length was 

significantly (p<0.05) reduced 

at the lowest and two highest 

treatment concentration yet 

their percent effect as 

compared to the negative 

control were between 2.5 -

5.3%. As the effect did not 

follow a dose response pattern 

and was not considered to be 

biologically significant, the 

NOAEC was determined as the 

highest treatment concentration

48400002

Acceptable

(2010)

Freshwater Benthic Invertebrates

Chronic

TGAI

98.8%

Freshwater amphipod, 

(Hyalella azteca)

42 d Sediment value: 

NOAEC (35-d 

survival and 

reproduction, 42-

d survival) =5.7

mg a.i./kg dw

Porewater value: 

NOAEC (35-d 

survival and 

reproduction, 42-

d survival) = 0.5 

mg a.i/L

 Mean percent survival after 42

days was 95, 93, 93, 77, 61, 71, 

and 24 mg a.i/kg sediment for 

the negative control, solvent 

control, and time weighted 

average sediment 

concentrations of 5.7, 10, 24, 

38, and 97 mg a.i/kg sediment 

levels, respectively

 Growth and reproduction data 

were dropped from analysis for 

28-d dry weight, 35-d number 

of offspring, and 42-d dry 

weight, number of offspring, 

and male to female ratio 

because of significant effects 

on survival at these intervals 

for varying concentrations

48400006

Acceptable

(2010)
28

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

TGAI 

94.7

Freshwater midge

(Chironomus riparius)

28 d Sediment value: 

NOAEC 

(development 

rate) = < 0.101

μg a.i/kg dw

Pore water value:

NOAEC 

(development 

rate) = <0.20 μg 

a.i/L

 Test vessels were spiked once 

via overlying water 

 Overlying water concentrations 

decline over time, while pore 

water and sediment 

concentrations increased

 Percent emergence was 75% or 

greater at all concentrations

 Definitive NOAEC was not 

reached for development rate 

due to effects at lowest 

treatment level 

48400007

Supplemental

(2009)

Estuarine/Marine Benthic Invertebrates

Chronic TGAI

98.8%

Saltwater amphipod

(Leptocheirus 

plumulosus)

28 d Sediment value: 

NOAEC/LOAEC 

= <3.0/6.3 mg 

a.i/kg dw (dry 

weight)

Pore water value:

NOAEC/LOAEC 

= <0.25/0.5 mg 

a.i/L (dry 

weight)

 Total mortality observed at 

highest two concentrations (25 

and 50 mg a.i/kg sediment

 Dry weight and number of 

offspring per female not 

significantly affected at two 

lowest treatment levels (3.0 

and 6.3 mg a.i/kg sediment). 

48400008

Supplemental

(2010)

Aquatic Plants

Vascular 

plants

TGAI

98.8%

Duckweed (Lemna 

gibba)

7 d EC50 (frond 

weight): 1.1 mg 

a.i./L (1.2 – 1.8)

NOAEC (frond 

weight): 0.60 

mg a.i./L

 The percent growth inhibition 

for treatment concentrations 

compared to the negative 

control ranged from -11 – 79% 

based on frond density, 1 – 9% 

based on frond weight, and 5 –

55% based on day 0 – 7 growth 

rate

 Fronds in the two highest 

treatment concentrations (2.3 

and 5.9 mg a.i/L, mean 

measured) had reduced root 

development relative to control 

fronds.

48400018

Acceptable

(2010)
29

Table 7. Toxicity reference values for aquatic organisms exposed to fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Algal 

toxicity

TGAI

98.8%

Cyanobacteria

(Anabaena flos-aquae)

96 h EC50 (cell 

density): 1.2 mg 

a.i/L (0.21 – 2.5)

NOAEC (cell 

density, growth 

rate, biomass): 

0.74 mg a.i/L

 The percent growth inhibition 

in treatment concentrations 

compared to the negative 

control ranged from 12 – 87% 

based on cell density. 

48400024

Acceptable

(2010)

TGAI

94.7%

Freshwater Green 

algae 

(Pseudokirchneriella 

subcaipta)

96 h EC50 (cell 

density): 0.16 mg 

a.i/L (0.12 –

0.22)

NOAEC (cell 

density): <0.053 

mg a.i/L 

EC05 (cell 

density): 0.029 

mg a.i/L (0.015 –

0.055)*

 The percent growth inhibition 

in the treatment concentrations 

compared to the negative 

control ranged from 26 – 95% 

based on cell density, 5 – 48% 

based on growth rate, and 15 –

92% based on biomass.

 At test termination, cells in the 

highest treatment concentration 

(0.9 mg a.i/L, mean measured) 

were observed to be bloated.

48400021

Acceptable

(2008)

Algal toxicity

TGAI

98.8%

Marine diatom

(Skeletonema 

costatum)

96 h EC50 (cell 

density): 0.027 

mg a.i/L (0.024 –

0.035)

NOAEC (cell 

density): <0.0045 

mg a.i/L

EC05: 0.002 (95% 

CI N/A)*

 The percent growth inhibition 

in the treatment concentrations 

compared to the negative 

control ranged from 3 – 97% 

based on cell density, the most 

sensitive endpoint.

48400022 

Acceptable

(2010)

TGAI 

98.8%

Freshwater diatom

(Navicula pelliculosa)

96 h EC50: (cell 

density): 0.011 

mg a.i/L (0.10 –

0.012)

NOAEC (cell 

density): 0.0049 

mg a.i/L

 The percent growth inhibition 

in the treatment concentrations 

compared to the negative 

control ranged from -11 – 99% 

on cell density. 

48400023 

Acceptable

(2010)

*EFED policy is to use the EC05 for estimation of risk to endangered aquatic plant in the event the NOAEC is nondefinitive.

Bolded values refer to the most sensitive endpoint for a given taxa to be used in quantitative risk assessment.
30

Table 8. Toxicity Reference Values For Aquatic Organisms Exposed to Degradation 

Products of Fenpyrazamine.

Degradation 

product

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

Freshwater invertebrates

MCNI TGAI

100%

Water flea

(Daphnia magna)

48 h EC50: >50 mg 

a.i/L (95% CI 

N/A)

Probit Slope: 

N/A

 Daphnids exposed to negative 

control, solvent control and 

limit concentration of 50 mg 

a.i/L which represents the 

degradation product’s limit of 

solubility.

 There were no mortality or 

sublethal effects observed in 

the controls or the single 

treatment concentration 

48399936

Acceptable

(2008)

S-2188-OH TGAI

98.4%

Water flea

(Daphnia magna)

48 h EC50 : >98 mg 

a.i/L (95% CI 

N/A)

Probit slope: 

N/A

 Daphnids were exposed to

negative control and limit 

concentration of 98 mg a.i/L, 

mean measured

 There were no mortality or 

sublethal effects observed in 

the control or the single 

treatment concentration 

48399937

Acceptable

(2008)

S-2188-DC TGAI 

100%

Water flea

(Daphnia magna)

48 h EC50 : >94 mg 

a.i/L (95% CI 

N/A)

Probit slope : 

N/A

 Daphnids were exposed to 

negative control and limit 

concentration of 94 mg a.i/L, 

mean measured

 There was no mortality and 

surviving daphnids in the sole 

treatment concentration were 

observed to have abnormal 

swimming 

48399938

Acceptable 

(2008)

Freshwater Fish

S-2188-DC TGAI

100%

Rainbow trout

(Oncorhynchos 

mykiss)

96 h LC50: > 89 mg 

a.i/L (95% CI 

N/A)

Probit slope: 

N/A 

 Fish were exposed to negative 

control and limit concentration 

of 89 mg a.i/L, mean measured

 There was no mortality or 

sublethal effects observed in 

the control or the single 

treatment concentration 

48399942

Acceptable

(2008)
31

Table 8. Toxicity Reference Values For Aquatic Organisms Exposed to Degradation 

Products of Fenpyrazamine.

Degradation 

product

% 

A.I. Species Dur.

Toxicity 

Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

(Year)

S-2188-OH TGAI

98.4%

Rainbow trout

(Oncorhynchos 

mykiss)

96 h LC50: > 97 mg 

a.i/L (95% CI 

N/A)

Probit slope: 

N/A 

 Fish were exposed to negative 

control and limit concentration 

of 97 mg a.i/L, mean measured

 There was no mortality or 

sublethal effects observed in 

the control or the single 

treatment concentration 

48400043

Acceptable

(2008)

Algal Toxicity

S-2188-DC TGAI

100%

Freshwater Green 

algae 

(Pseudokirchneriella 

subcapita)

96 h

EC50 (cell 

density): 32 mg 

a.i/L (30-35)

NOAEC (cell 

density): 1.6 mg 

a.i/L

 The percent growth inhibition 

I the treatment concentrations 

as compared to the negative 

control ranged from 1.1 to 

89.3% based on cell density, 

0.3 to 22.6% based on growth 

rate, and 1.1 to 57.6% based 

on biomass. 

48400019

Acceptable

(2008)

S-2188-OH 98.4

Freshwater Green 

algae 

(Pseudokirchneriella 

subcapita)

96 h

EC50 (cell 

density): 55 mg 

a.i/L) (46-65)

NOAEC (cell 

density): 3.1 mg 

a.i/L

 The percent growth inhibition 

in the treatment concentrations 

as compared to the negative 

control ranged from -2.3 to 

72% based on cell density, -

0.37 to 20% based on growth 

rate, and -1.2 to 66% based on 

biomass.

48400020

Acceptable

(2008)

 Freshwater Fish

Acute toxicity studies with technical-grade fenpyrazamine were available for 2 species of 

freshwater fish: rainbow trout and bluegill sunfish. All studies were conducted on TGAI with 

94.7% purity. In the rainbow trout study (MRID 48399945), fenpyrazamine was administered in 

a flow-through exposure system and caused 100% mortality at the highest treatment 

concentration (7.8 mg a.i/L, mean measured). All other treatment concentrations and control had 

mortality at or below 5%. There were no sublethal effects noted in the lowest two treatment 

concentrations. At the two higher treatment concentrations (2.1 and 3.8 mg a.i/L, mean 

measured), 7 and 20 fish exhibited lethargy in those treatment concentrations, respectively. In 

the bluegill sunfish study (MRID 48399944), TGAI fenpyrazamine was administered in a flow 

through system. The two highest treatment concentrations (6.9 and 12 mg a.i/L, mean measured) 

had 85 and 100 % mortality, respectively while the controls and other treatment concentrations 

had 0% morality during the study. All fish in the highest treatment concentration exhibited a 

complete loss of equilibrium after three hours of exposure and were dead by six hours. This 
32

study has an LC50 of 5.4 mg a.i/L and is classified as acceptable. For risk assessment purposes, 

an acute toxicity value of 5.2 mg a.i/L (MRID 48399945) will be used for estimating acute 

risk quotients for freshwater fish. 

There were two additional acute freshwater fish toxicity studies submitted with degradation 

products of fenpyrazamine. Both studies were conducted with the rainbow trout. In one study

conducted with 98.4% purity of degradation product S-2188-OH (MRID 48400043 ) at a single 

treatment concentration (97 mg a.i/L, mean measured), there were no mortalities or sublethal 

effects observed. This study has an LC50 of 5.2 mg a.i/L and is classified as acceptable. In 

another acute study conducted with 100% purity S-2188-DC (MRID 48399942), there were no 

mortalities or sublethal effects noted at the sole treatment concentration in the study, 89 mg a.i/L, 

mean measured. This study has an L50 of >89 mg a.i/L and is classified as acceptable. 

An acceptable chronic early life stage test with a freshwater fish (rainbow trout, MRID 

48400003) was conducted with TGAI fenpyrazamine (94.7% purity). Fertilized egg/embryos 

were exposed at mean measured concentrations of 50, 100, 190, 370, and 750 μg a.i/L. Embryo 

viability was determined on Day 19 and averaged 62 and 67% for the negative and solvent 

controls, respectively, and 70, 69, 70, 61, and 68% for the increasing treatment concentrations, 

respectively. On day 30 of the study (Day 0, post-hatch) larval survival was significantly 

reduced (p<0.05) at the highest treatment concentration. On day 90 of the study (Day 60, posthatch) larval survival was also significantly reduced (p<0.05) only at the highest treatment 

concentration as compared to the negative control. Mean total length, wet weight, and dry

weight data were excluded for the highest treatment concentration due to effects on larval 

survival at that treatment concentration. For those three endpoints, there were no significant 

reductions (p<0.05) as compared to the negative control. The NOAEC and LOAEC for this 

study was determined to be 370 and 750 μg a.i/L, respectively based on effects to Day-0 post 

hatch larval survival and Day-60 post hatch larval survival. For risk assessment purposes, a 

chronic toxicity of 370 μg a.i/L will be used for estimating chronic risk quotients for 

freshwater fish. 

 Freshwater Invertebrates

An acute toxicity study conducted with TGAI fenpyrazamine (94.7%) on freshwater 

invertebrates was available for Daphnia magna. A 48-h EC50 of 5.5 mg a.i/L was determined on 

the basis of immobilization. Mortality/immobilization was 95% at the highest treatment 

concentration (8.0 mg a.i/L, mean measured), 5% at the second highest treatment concentration 

(3.8 mg a.i/L, mean measured) and 0% at the remaining treatment concentrations and controls. 

There was a 55% portion of daphnids observed to be lethargic at test termination in the lowest 

treatment concentration (0.61 mg a.i/L, mean measured) while 100% of the surviving daphnids 

in the remaining treatment concentrations were observed to be lethargic. This study is classified 

as acceptable. For risk assessment purposes, an acute toxicity of 5.5 mg a.i/L will be used 

for estimating acute risk quotients for freshwater invertebrates. 

There were three additional acute freshwater invertebrate toxicity studies submitted with 

degradation products of fenpyrazamine. All studies were conducted with the Daphnia magna. 
33

In one study conducted with 98.4% purity of degradation product S-2188-OH (MRID 48399937) 

at a single treatment concentration (98 mg a.i/L, mean measured), there were no mortalities or 

sublethal effects observed and therefore this study had an EC50 value determined to be >98 mg 

a.i/L. In another acute study conducted with 100% purity S-2188-DC (MRID 48399938), there 

were no mortalities or sublethal effects noted observed in the study and therefore the study had 

an EC50 determined to be >94 mg a.i/L. Finally, a study with the degradation product MCNI 

(100% purity) (MRID 48399936) was submitted and conducted with a sole treatment 

concentration of 50 mg a.i/L which represents the limit of solubility for this degradate. There 

were no mortalities or sublethal effects observed during the study and therefore the EC50 was 

determined to be >50 mg a.i/L. All studies were classified as acceptable.

A freshwater invertebrate (Daphnia magna) lifecycle test with fenpyrazamine TGAI (94.7%) 

was submitted and found to be acceptable (MRID 48400001). Daphnids were exposed 

throughout their life cycle to mean measured concentrations of fenpyrazamine ranging from 

0.085 to 1.4 mg a.i/L for 21 days. Survival ranged from 90 to 100% for all levels, with no 

statistically-significant differences indicated at any treatment level compared to the negative 

control. The cumulative number of offspring released per female after 21 days was significantly 

reduced (p<0.05) at the two highest treatment concentrations (0.76 and 1.4 mg a.i/L, mean 

measured) as compared to the negative control. The number of immobilized offspring, if any, 

was not reported. At study termination, mean total body lengths of surviving daphnia were 

significantly reduced (p<0.05) compared to the negative control at the two highest treatment 

concentrations. Mean dry weights of surviving daphnia were only significantly reduced (p<0.05) 

at the highest treatment concentration. It was reported that the first brood released occurred on 

Day 7 at the negative control, solvent control, and the three lowest treatment concentrations 

(0.085, 0.18, and 0.34 mg a.i/L, mean measured). At the second highest treatment concentration, 

this time was Day 9 and at the highest treatment concentration this time was Day 10. There were 

no conclusions drawn by the study author, but the data support a treatment-related delay at the 

two highest treatment concentrations for time to first brood. The most sensitive endpoints of the 

study were time to first brood release and total length of surviving daphnids with NOAEC and 

LOAEC values of 0.34 and 0.76, respectively. For risk assessment purposes, a chronic 

toxicity value of 0.34 mg a.i/L will be used for estimating chronic risk quotients for 

freshwater invertebrates.

 Estuarine/Marine Fish

One acute toxicity study was submitted conducted with TGAI fenpyrazamine (98.8% purity) to 

the sheepshead minnow (MRID 48399946). Mortality was observed at 20% in the highest test 

concentration (3.9 mg a.i/L, mean measured) but was 0% in all other treatment concentrations. 

There were no sublethal effects observed in the negative control and all treatment concentrations 

except the highest. At the 3.9 mg a.i/L level, there were several (number not defined in the study

report) fish that were reported as being lethargic and two surviving fish that exhibited a partial 

loss of equilibrium. The LC50 for this study was determined to be >3.9 mg a.i/L and this study is 

classified as acceptable. For risk assessment purposes, an acute toxicity value of 3.9 mg a.i/L 

will be used for estimating acute risk quotients for estuarine/marine fish (i.e., a lower 

bound of 3.9 mg a.i/L will be assumed as a screen for acute effects).
34

An estuarine/marine chronic fish early life stage test conducted with fenpyrazamine TGAI 

(98.8%) on the sheepshead minnow was submitted and found to be supplemental (non-definitive 

NOAEC for most sensitive endpoint and clinical signs of toxicity not noted, MRID 48400004). 

Embryos to their larval stage were exposed to fenpyrazamine levels ranging from 0.039 to 1.2 

mg a.i/L for 33 days. There were no treatment-related effects on hatching success (assessed on 

Day 5) or post-hatch survival) assessed on Day 33) observed with no significantly different 

(p<0.05) effects when compared to the negative control. Mean percent hatching success ranged 

from 92 to 98% across all treatment concentrations (including the negative control) and mea 

larval survival ranged from 95 to 100%. Total length measurements were significantly reduced 

from the negative control (p<0.05) at all treatment levels. Dry weights were significantly 

reduced (p<0.05) at the two highest treatment concentrations (0.58 and 1.2 mg a.i/L, mean 

measured). The most sensitive endpoint of the study was total length of surviving larval fish 

with NOAEC and LOAEC values of <0.039 and 0.039 mg a.i/L, respectively. For risk 

assessment purposes, a chronic toxicity value of 0.039 mg a.i/L will be used for estimating 

chronic risk quotients for freshwater fish (i.e., an upper bound of 0.039 mg a.i/L will be 

assumed as a screen for chronic effects).

 Estuarine/Marine Invertebrates

Acceptable acute toxicity studies were available for two species of estuarine/marine 

invertebrates: the mysid shrimp (Americamysis bahia; MRID 48399941) and eastern oyster 

(Crassotrea virginica; MRID 48399940, both conducted with TGAI fenpyrazamine (98.8% 

purity). With mysids, a 96-h LC50 value of 0.83 mg a.i/L was determined from the study. Total 

mortality occurred in the three highest treatment concentrations (1.2, 2.3, and 4.6 mg a.i/L, mean 

measured). 

With the eastern oyster, a 96-h EC50 for shell deposition was determined to be 0.78 mg a.i/L. 

Shell growth was reduced by 30.4, 21.7, 21.7, 30.4, and 73.9 % relative to the negative control at 

the 0.066, 0.12, 0.24, 0.49, and 1.0 mg a.i/L treatment concentrations, respectively (mean 

measured concentrations). There was no mortality observed in the study. For risk assessment 

purposes, an acute toxicity value of 0.78 mg a.i/L will be used to assess acute risks to 

estuarine/marine invertebrates.

An estuarine/marine invertebrate (Americamysis bahia) lifecycle test with fenpyrazamine TGAI 

(98.8 %) was submitted and found to be acceptable (MRID 48400002). Mysids were exposed 

throughout their life cycle to mean measured concentrations of fenpyrazamine ranging from 3.2 

– 98 μg a.i/L for 28 days. Parental survival ranged from 83 - 100% for all levels, with no 

statistically-significant differences indicated at any treatment level compared to the negative 

control. The cumulative number of offspring released per female after 28 days was also not

significantly reduced (p<0.05) at any of the treatment concentrations. Male and female mean dry

weight, time to first brood release and male mean total length were also not significantly reduced 

from the negative control. For female total body length, statistical hypothesis testing determined 

a significant effect (p<0.05) at the 3.2, 47, and 98 μg a.i/L treatment concentrations. However 

these effects were 3.5, 5.3 and 2.5 % reductions from the negative control and because they did 
35

not follow a dose responsive pattern, it was determined that the NOAEC for this endpoint was 

the highest treatment concentration (98 μg a.i/L) for which there was a 2.5 % reduction from 

control. Therefore the NOAEC and LOAEC for this study were 98 and >98 μg a.i/L, 

respectively. For risk assessment purposes, a chronic toxicity value of 98 μg a.i/L will be 

used for estimating chronic risk quotients for estuarine/marine invertebrates (i.e., a lower 

bound of 98 μg a.i/L will be assumed as a screen for chronic effects).

 Benthic (Sediment Dwelling) Invertebrates

Effects of fenpyrazamine on freshwater benthic invertebrates are available from two studies: a 

42d exposure via spiked sediment to the amphipod Hyalella azteca (MRID 48400006) and a 28d 

exposure via spiked overlying water to the midge Chironomus riparius (MRID 48400007). In 

the Hyalella study, 8 day old amphipods were exposed to spiked sediment concentrations that 

were time weighted averaged to yield 5.7, 10, 24, 38, and 97 mg a.i/L. On Day 28, survival was 

statistically significant (p<0.05) in the three highest treatment concentrations when compared to 

the negative control. These treatment concentrations were excluded from the Day 28 dry weight 

analysis and there were no significant reductions from the negative control in the two lowest 

treatment concentrations. On Day 35, survival was significantly reduced (p<0.05) at all but the 

lowest treatment concentration as compared to the negative control. The number of offspring per 

female had significant (p<0.05) at all but the lowest treatment concentration when compared to 

the negative control. On Day 42, survival was significantly reduced (p<0.05) when compared to 

the negative control at the three highest treatment concentrations. These three concentrations 

were excluded from further statistical analysis for Day 42 dry weights, number of offspring per 

female, and male to female ratio endpoints. For Day 42 dry weights, number of offspring per 

female, and male to female ratio, there were no significant (p<0.05) effects at the two lowest 

treatment concentrations when compared to the negative control. On the basis of sediment dry

weight and pore water, the NOAECs from this study are 5.7 mg/kg dw sediment and 0.5 mg 

a.i/L, respectively for the most sensitive endpoints which are Day 35 survival, Day 35 number of 

offspring per female and Day 42 survival. This study is classified as acceptable.

Results from the chronic study on C. riparius indicate a much lower NOAEC for this species 

compared to the chronic study with amphipod (<101 μg a.i/kg sediment for midge vs. 5700 μg 

a.i./kg sediment for amphipod). This lower NOAEC likely reflects a combination of factors 

including interspecies differences in sensitivity to fenpyrazamine and measurement of additional 

endpoints (e.g., development rate). It is important to note, however, that this study involved 

exposure via the overlying water and concentrations varied considerably over time. Specifically, 

both pore water and sediment concentrations increased dramatically from day 0 to day 28, while 

overlying water concentrations decreased, thus reflecting the expected partitioning of 

fenpyrazamine to sediments from the water column. Freshwater midges were exposed to time 

weighted averaged sediment concentrations of 101, 215, 326, 611, and 790 μg a.i/kg dw 

sediment. Percent emergence was significantly reduced (p<0.05) at the two highest treatment 

concentrations as compared to the negative control. The combined male and female 

development rate was significantly reduced (p<0.05) at the two lowest and two highest treatment 

concentrations. Although the test guideline followed in this study (OECD 219) is designed to 

mimic a spray drift event, a study that uses spiked sediment, simulating a runoff or erosion event 
36

is preferred. OCSPP test guidelines recommend that sediments be equilibrated with test 

compound prior to testing. This study is classified as supplemental for this reason as well as the 

fact that a definitive NOAEC was not achieved for the most sensitive endpoint of this study. For 

risk assessment purposes, a toxicity value of 101 μg a.i/L will be used for estimating chronic 

risk quotients for freshwater benthic invertebrates in the sediment and 20 μg a.i/L for 

freshwater benthic invertebrates in the pore water (i.e., an upper bound of 101 μg a.i/kg dw 

sediment and 20 μg a.i/L will be assumed as a screen for chronic effects).

The effects of fenpyrazamine on the saltwater amphipod, Leptocheirus plumulosus, were 

examined in a 28-d spiked sediment exposure study (MRID 48400008). Time weighted average 

concentrations of 3.0, 6.3, 12, 25, and 50 mg a.i/kg dw sediment in addition to solvent and 

negative controls. Survival was significantly reduced (p<0.05) at the two highest treatment 

concentrations as compared to the negative control. The number of offspring per female was 

significantly reduced (p<0.05) at the 12 mg a.i.kg dw sediment treatment concentration when 

compared to the negative control. For mean dry weight, there were significant reductions 

(p<0.05) at all three treatment concentrations that were not excluded from the analysis due to 

effects on survival. The resultant NOAEC and LOAEC for this study was <3 and 3 mg a.i/kg dw 

sediment based on effects to dry weights. The corresponding NOAEC and LOAEC for pore 

water concentrations is <0.25 and 0.25 mg a.i/L. This study was classified as supplemental as it 

does not achieve a definitive NOAEC for the most sensitive endpoint of the study. For risk 

assessment purposes, a toxicity value of 3 mg a.i/kg dw sediment will be used for estimating 

chronic risk quotients for estuarine/marine benthic invertebrates in the sediment and 0.25 

mg a.i/L for estuarine/marine benthic invertebrates in the pore water (i.e., an upper bound 

of 3 mg a.i/kg dw sediment and 0.25 mg a.i/L will be assumed as a screen for chronic 

effects).

 Vascular and Non-vascular Aquatic Plants

One vascular aquatic plant study (MRID 48400018) was submitted along with three non-vascular

aquatic plant studies (algae) were submitted conducted with TGAI fenpyrazamine (MRIDs 

48400021, 48400022, 48400023, and 48400024).

In the aquatic vascular plant toxicity study, Lemna gibba (duckweed) was exposed to mean 

measured treatment concentrations ranging from 0.023 to 5.9 mg a.i/L. The percent growth 

inhibition in the treated culture as compared to the negative control ranged from -11 to 79% 

based on frond density, 1 to 90% based on frond weight, and 5 to 55% based on days 0 to 7 

growth rate. Fronds in the two highest treatment groups were smaller and had reduced root 

development relative to the negative control. There were no other morphological abnormalities 

noted in the negative control or any other treatment concentrations. The most sensitive endpoint 

for this study was frond weight with a 96-h EC50 and NOAEC value of 1.1 and 0.060 mg a.i/L, 

respectively. This study is classified as acceptable. For risk assessment purposes, a toxicity 

value of 1.1 mg a.i/L will be used to assess risk to non-listed aquatic vascular plants while a 

value of 0.060 mg a.i/L will be used to assess risk to listed aquatic vascular plants. 

Four acceptable studies with aquatic non-vascular plants (algae) were submitted with TGAI
37

fenpyrazamine (94.7 – 98.8% % purity). In one study conducted with freshwater green algae 

(Pseudokirchneriella subcapitata, MRID 48400021), fenpyrazamine was exposed to cultures 

ranging from 0.053 to 0.90 mg a.i/L, mean measured concentrations. The percent growth 

inhibition in the treated algal culture as compared to the negative control ranged from 26 to 95% 

based on cell density, 5 to 48% based on growth rate, and 15 to 92% based on biomass. At test 

termination, cells at the highest treatment concentration were observed to be bloated while cells 

in the negative control and remaining treatment concentrations appeared normal. The most 

sensitive endpoint was cell density with 96-h EC50 and NOAEC values of 0.16 and <0.053 mg 

a.i/L, respectively. As the NOAEC for this endpoint was non-definitive, EFED policy is use the 

EC05 in place of the NOAEC for this endpoint, which was determined to be 0.029 mg a.i/L.

In an acceptable study with the marine diatom Skeletonema costatum (MRID 48400022), TGAI 

fenpyrazamine was exposed in mean measured concentrations of 0.0045, 0.011, 0.028, 0.18, 

0.42, and 1.2 mg a.i/L to cultures. The percent growth inhibition in the treated algal culture as 

compared to the negative control ranged form 3 to 97% based on cell density, the most sensitive 

endpoint. Cells in the negative control group and all treatment concentrations appeared normal 

throughout the duration of the test. The 96-h EC50 and NOAEC values for this test (based on cell 

density) are 0.027 and <0.0045 mg a.i/L. As the NOAEC for this endpoint was non-definitive, 

EFED policy is use the EC05 in place of the NOAEC for this endpoint, which was determined to 

be 0.002 mg a.i/L. 

In an acceptable study with the freshwater diatom Navicula pelliculosa, (MRID 48400023), 

TGAI fenpyrazamine was exposed in mean measured concentrations of 0.0049, 0.012, 0.030, 

0.074, 0.019, and 0.47 mg a.i/L to cultures. The percent growth in the treated algal culture as 

compared to the negative control ranged from -11 to 99% based on cell density, the most 

sensitive endpoint. Cells in the negative control group and all treatment concentrations appeared 

normal throughout the duration of the test. The 96-h EC50 and NOAEC values form this test 

(based on cell density) are 0.011 and 0.0049 mg a.i/L, respectively. 

A study conducted with TGAI fenpyrazamine on the cyanobacteria Anabaena flos-aquae (MRID 

48400024) exposed cultures to mean measured concentrations of 0.045, 0.12, 0.28, 0.74, 1.8, and 

4.6 mg a.i/L. The percent growth inhibition in the treated algal culture as compared to the 

negative control ranged from 12 to 87% based on cell density, the most sensitive endpoint. Cells 

in the negative control and treatment concentrations appeared normal throughout the duration of 

the study. The 96-h EC50 and NOAEC values (based on cell density) were 1.2 and 0.74 mg a.i/L. 

This study is classified as acceptable. For risk assessment purposes, a toxicity value of 0.011

mg a.i/L will be used to assess risk to non-listed aquatic non-vascular plants while a value 

of 0.0049 mg a.i/L will be used to assess risk to listed aquatic non-vascular plants. 

Additionally, two acceptable aquatic non-vascular plant toxicity studies were submitted with 

degradation products of fenpyrazamine. Both studies were acceptable and exposed degradation 

products to the freshwater green algae Pseudokirchneriella subcapitata. In one study with S2188-DC (100% purity) green algae cultures were exposed to mean measured concentration is 

1.6, 3.0, 6.0, 13, 24, 47, and 98 mg a.i/L. The percent growth inhibition in the treated algal 

culture as compared to the negative control ranged from 1.1 to 89.3 % based on cell density, 0.3 
38

to 22.6% based on growth rate, and 1.1 to 57.6% based on biomass. Aggregation was observed 

in the three highest treatment concentrations. There were no morphological abnormalities 

observed in any treatment concentration throughout the 96-hour exposure period. The EC50 and 

NOAEC values (based on cell density) are 32 and 1.6 mg a.i/L, respectively.

In another study conducted with Pseudokirchneriella subcapitata, the fenpyrazamine degradate 

S-2188-OH (98.4% purity) was exposed to cultures at mean measured concentrations of 1.6, 3.1, 

6.3, 13, 25, 48, and 99 mg a.i/L. The percent growth inhibition in the treated algal culture 

compared to the negative control ranged from -2.3 to 72% based on cell density, -0.37 to 20% 

based on growth rate, and -1.2 to 66% based on biomass. Aggregation was observed in the three 

highest treatment concentrations. There were no morphological abnormalities observed in any 

treatment concentrations throughout the 96 hour exposure period. The EC50 and NOAEC values 

based on cell density were 55 and 3.1 mg a.i/L, respectively. 

4.4.2 Terrestrial Effects

All toxicity reference values used to assess the potential acute and chronic risks of 

fenpyrazamine exposure to birds and mammals were obtained from acceptable or supplemental 

studies using fenpyrazamine TGAI (Table 9). 

Table 9. Toxicity Reference Values For Terrestrial Organisms Exposed To 

Fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

Avian Toxicity

Acute

TGAI 

98.8%

Canary 

Serinus canaria 

(Acute Oral)

14 d LD50 >2000 mg a.i/kg 

bw (95% CI not 

available)

 No mortalities in control or at the 

2000 mg a.i/kg bw treatment 

concentration 

 No clinical signs of toxicity or 

sublethal effects were observed

48400010 

Acceptable

(2010)

TGAI 

97.7%

Mallard Duck 

Anas 

platyrhynchos

(Subacute, 

Dietary)

8 d LC50 >4430 mg a.i/kg 

diet (95% CI not 

available)

 Five mortalities were observed 

during the study, three in the 

2360, and two in the 4430 mg 

a.i/kg diet treatment 

concentrations, mean measured

 Group body weight gain was 

significantly reduced (p<0.05) at 

the 4430 mg a.i/kg diet 

48400012 

Acceptable

(2006)

TGAI 

94.7%

Bobwhite Quail 

Colinus 

virginianus

(Acute Oral)

14 d LD50 >2000 mg a.i/kg 

bw

Probit slope: N/A

 No mortalities in control or at the 

5000 mg/kg test level. 

 No clinical signs of toxicity or 

sublethal effects observed at all 

treatment concentrations 

48400009 

Acceptable

(2006)
39

Table 9. Toxicity Reference Values For Terrestrial Organisms Exposed To 

Fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

TGAI 

94.7%

Bobwhite Quail 

Colinus 

virginianus

(Subacute 

Dietary)

8 d LC50: >5039 mg a.i/kg 

diet (95% CI not 

available)

 The only mortality in the study 

occurred in the highest treatment 

concentration (5039 mg a.i/kg 

diet, mean measured)

 Group body weight gain was 

significantly reduced (p<0.05) at 

the two highest treatment levels 

(2687 and 5039 mg a.i/kg diet)

 Clinical sings of toxicity included 

wing droop and lethargy which 

were observed in two birds in the 

highest treatment concentration, 

one of which later died, 

representing the single mortality 

in the study 

48400011

Acceptable

(2006)

Chronic TGAI 

94.7%

Mallard Duck 

Anas 

platyrhynchos

22 

wk

NOAEC=517 mg 

a.i/kg diet 

LOAEC=1022 mg 

a.i/kg diet

 One adult mortality was observed 

during the test

 No clinical sings of toxicity, 

effects on food consumption, or 

effects on reproductive 

parameters were observed at any 

treatment concentration during 

the test

 14-day survivor body weight in 

the 1022.3 mg a.i/kg diet 

treatment concentration (the 

highest tested) was significantly 

reduced (p<0.05) from the 

control) 

48400013

Acceptable

(2008)

TGAI 

94.7%

Bobwhite Quail 

Colinus 

virginianus

24 

wk

NOAEC= 248 mg 

a.i/kg diet 

LOAEC=495 mg 

a.i/kg diet

 Three adult mortalities although 

post mortem analysis showed 

they may not have been chemical 

related

 There were significant (p<0.05) 

reductions in adult female body 

weight gain at the 495 mg a.i/kg 

diet test concentration

48400014 

Acceptable

(2008)

Mammals

Acute

TGAI

94.8%

Rat

(Rattus 

norvegicus)

14 d LD50 >2000 mg ai/kg 

bw (females)

 No mortality occurred in the 

study

 No abnormal clinical sings of 

toxicity were evident

 One anima had fluid retention in 

the uterus at post mortem not 

considered to be treatment related

48400106

Acceptable

(2007)
40

Table 9. Toxicity Reference Values For Terrestrial Organisms Exposed To 

Fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

Chronic TGAI

94.7%

Rat

(Rattus 

norvegicus)

2 

gen

NOAEL = 1000 ppm

LOAEL = 3000 ppm

 There were no treated related 

mortalities or clinical signs of 

toxicity in any generation

 In the parental generation and F1 

generation, there were no 

significant (p<0.05) differences 

in body weight gain

 There was a statistically 

significant decrease (p<0.05) in 

food consumption of parental 

females during pre-mating and 

gestation of the highest treatment 

level

 There were no effects on oestrus 

cycle, number of pairs mating, 

time to mating, number of 

females becoming pregnant, or 

the length of gestation in the P 

and F1 generation parents

 Mean pup weight of F1 pups at 

birth and 21 days post partum 

was significantly lower (p<0.05) 

in the highest treatment level

 There was a significant reduction 

(p<0.05) in the mean number of 

implantations per dam and litter 

size, and a statistically significant

increase in post implantation loss.

48400127

Acceptable

(2009)

Nontarget Insects - Bees

Acute

TGAI 

94.7%

Honeybee Apis 

mellifera

(Acute contact 

toxicity)

48 h LD50: > 100 ug ai/bee 

(95% CI N/A)

Probit slope: N/A

 Mortality was 0, 3.3, 13.3, 6.7, 

13.3, and 26.6% at the 1.9, 4.3, 

9.4, 21, 45, and 100 μg a.i/bee 

treatment concentrations

 Mortality in the negative and 

solvent controls was 10% and 

3.3%, respectively. 

48400015

Acceptable

(2006)

TGAI 

97.6%

Honeybee 

Apis mellifera

(Oral toxicity

study)

48 h LD50: > 100 ug ai/bee 

(95% CI N/A)

Probit slope: N/A 

 Mortality was 10, 6.7, 3.3, 23, 

20% at the 6.3, 13, 25, 50, and 

100 μg a.i/bee 

 Mortality in negative and solvent 

controls was 0%.

48399935

Supplemental

(2006)
41

Table 9. Toxicity Reference Values For Terrestrial Organisms Exposed To 

Fenpyrazamine.

Exposure 

Scenario

% 

A.I. Species Dur.

Toxicity Reference 

Value 

(95% CL)

Effect Notes

MRID;

Classification 

Other Non-target Terrestrial Organisms

Acute TGAI 

94.7%

Earthworm 

(Eisenia fetida)

14 d

LC50: >800 mg a.i/kg 

dw soil

NOAEC (body 

weight): 25 mg a.i/kg 

soil

 Mortality was 0, 0, 0, 0, 0, 2.5, 

7.5, and 2.5 % at the negative 

control, solvent control, and the 

25, 50, 100, 200, 400, and 800 

mg a.i/kg soil concentrations

 Body weight was significantly 

reduced (p<0.05) at all but lowest 

concentration

48400025 

Supplemental

(2006)

Terrestrial Plant

Seedling 

emergence

TEP 

44.4%

Multiple 

species

21 d

Most sensitive 

monocot: corn

EC25 (survival): 

>1.54 lbs a.i/A (95%

CI: N/A)

Slope : 2.97

NOAEC: 0.15 lbs 

a.i/A

-----------------------

Most sensitive dicot, 

flax

EC25 (weight): >0.53 

lbs a.i/A (95% CI: 

N/A)

Slope: 5.31

NOAEC: <0.035 lbs 

a.i/A

 The percent inhibition to seedling 

emergence in the treated species 

compared to negative control 

ranged from -20 – 27.6%

 Phytotoxic effects included 

necrosis, leaf curl, stem curl, and 

unshed seed coat.

 Corn was most sensitive monocot 

based on effects to survival

 Flax was most sensitive dicot 

based on effects to biomass 

(weight)

48400016

Supplemental

(2010)

Vegetative 

vigor

TEP 

44.4%

Multiple 

species

21 d

Most sensitive 

monocot

EC25: Could not be 

determined due to 

lack of toxicity

NOAEC: 0.56 lbs 

a.i/A

-----------------------

Most sensitive dicot

EC25: Could not be 

determined due to 

lack of toxicity

NOAEC: 0.56 lbs 

a.i/A

 The % survival in all species was 

not significantly affected and the 

% inhibition of survival ranged 

from to 4.2%. 

 Phytotoxic effects included 

necrosis, leaf curl, stem curl, and 

unshed seed coat.

 Length (height) and weight 

endpoints were not significantly 

affected at any treatment 

concentration for any species.

48400017

Supplemental

(2010)

Bolded values refer to the most sensitive endpoint for a given taxa to be used in quantitative risk assessment.
42

 Birds (Acute Toxicity)

Acute oral and subacute dietary toxicity studies are available for three avian species (northern 

bobwhite quail, mallard duck, and canary) in three orders (Galliformes, Anseriformes, 

Passeriformes). Overall, these studies indicate that fenpyrazamine is practically non-toxic to 

these species of birds on an acute exposure basis. The acute oral LD50 values are > 2000 mg

a.i/kg bw for both the northern bobwhite quail and canary studies (MRIDs 48400009 and 

48400010, respectively) since no treatment-related mortality occurred at the highest dose tested. 

Furthermore, there were no treatment-related sublethal signs of toxicity (body weight, food 

consumption) were reported in these studies. In the canary study within the first hour of dosing, 

3 birds regurgitated at the limit dose. However, these birds were immediately replaced and none 

of the remaining birds regurgitated or showed other sublethal signs of toxicity. Therefore, the 

study validity is not considered to be impacted by this low rate of regurgitation. All three acute 

oral studies are classified as acceptable. For risk assessment purposes, an acute oral LD50 of 

> 2000 mg a.i/kg bw) for passerines will be used qualitatively to evaluate potential acute 

effects to birds (i.e., a lower bound of 2000 mg a.i/kg bw will be assumed as a screen for 

acute effects).

There were two subacute studies submitted for the northern bobwhite quail and mallard duck 

(MRIDs 48400011 and 48400012, respectively). In the northern bobwhite quail study, TGAI 

fenpyrazamine was exposed in the diet at mean measured concentrations of 306.9, 628.1, 1318, 

2687, and 5039 mg a.i/kg diet. There was a single mortality that occurred at the highest 

treatment concentration. The bird displayed wing droop and lethargy prior to death. There were 

no other clinical signs of toxicity that were observed during the test. Mean body weight gain in 

the three highest treatment concentrations was significantly lower (p<0.05) as compared to the 

negative control. There were no treatment related effects on food consumption noted. The 

resultant LC50 for the study was >5039 mg a.i/kg-diet and this study was classified as acceptable. 

For the mallard duck study, TGAI fenpyrazamine was administered in the diet at 291 568, 1210, 

2360, and 4430 mg a.i/kg-diet (mean measured concentrations). There were a total of five 

mortalities that occurred during the study, three birds at the 2360 and two birds at the 4430 mg 

a.i/kg-diet treatment concentrations. There were no clinical signs of toxicity noted during the 

study. The mean body weight gain was significantly lower (p<0.05) at the highest treatment 

concentration compared to the negative control. There were no treatment related effects on food 

consumption noted during the study. The resultant LC50 for this study was >4430 mg a.i/kg-diet 

and this study is classified as acceptable. For risk assessment purposes, a subacute dietary 

LC50 of > 4430 ppm in the diet) will be used qualitatively to evaluate potential acute effects 

to birds (i.e., a lower bound of 4430 ppm will be assumed as a screen for acute effects).

 Birds (Chronic Toxicity)

Two studies were submitted that examined the chronic toxicity of fenpyrazamine to avian 

species. In the study with mallard duck (MRID 48400013) fed 26 week old mallards (4 groups 

of 16 replicate pairs/group including control) approaching their first breeding season a diet 

containing 258, 517 or 1000 mg a.i/kg-diet of TGAI fenpyrazamine (94.7%i). There was a single 
43

adult mortality observed during the test from the control group that was found dead 

approximately 19 weeks post treatment. There were no overt clinical signs of toxicity observed 

at any of the treatment concentrations nor were there any treatment related effects on adult body 

weight or food consumption. Mean 14-day survivor body weight was significantly reduced 

(p<0.05) in the highest treatment concentration as compared to the negative control. The study

author did not consider this to be a treatment related effect, citing one reason as a failure to 

detect a similar effect in the companion northern bobwhite quail study (MRID 48400014). The 

study reviewer however did find evidence of a treatment related effect for this endpoint and 

therefore could not dismiss the effects observed in this study. Aside from this effect on 14-day

survivor body weight, there were no other statistically significant treatment related effects on any

reproductive parameters at any treatment concentration. The resultant NOAEC and LOAEC for 

this study were 519 and 1022 mg a.i/kg-diet, respectively based on 14-day survivor body weight 

and the study is classified as acceptable. 

In the study with the northern bobwhite quail (MRID 48400014) fed 28 week old quail (4 groups 

of 18 replicate pairs/group including control) approaching their first breeding season a diet 

containing mean measured concentrations of 248, 495, and 978 mg a.i/kg-diet of TGAI

fenpyrazamine (94.7%). There were three adult mortalities that occurred during the study, none 

of which were considered treatment related. There were no overt clinical signs of toxicity

observed at any of the treatment concentrations. There were no significant reductions in 

hatchling body weight, however there was a slight significant reduction (p<0.05) of 14-day

survivors at the 495 mg a.i/kg-diet treatment concentration. There were no other statically 

significant effects on any other reproductive parameter at any treatment concentration. The 

resultant NOAEC and LOAEC for this study was 248 and 495 mg a.i/kg-diet, respectively, based 

on 14-day survivor body weight and the study is classified as acceptable. The dietary chronic 

NOAEL of 248 ppm will be used in estimating chronic risk quotients to avian species. 

 Mammals (acute toxicity)

For evaluating acute oral toxicity for mammals, an acute study with the rat (MRID 48400106) 

was conducted with TGAI fenpyrazamine (94.8%) at a single treatment concentration. There 

were no mortalities observed during the study along with no treatment related effects on body

weight or clinical signs of toxicity. The LD50 was therefore determined to be >2000 mg a.i/kgbw which categorizes fenpyrazamine as practically non-toxic to mammals on an acute oral basis. 

This study is classified as acceptable. An acute oral LD50 value of 2000 will be used as a 

lower bound for estimating acute RQs for mammals.

 Mammals (chronic toxicity)

There was an acceptable chronic two-generation reproduction study conducted with the Norway

rat submitted in support of fenpyrazamine (MRID 48400127). TGAI (94.7%) fenpyrazamine 

was administered continuously in the feed to rats at dietary concentrations of 0, 400, 1000, and 

3000 ppm. The toxicological response of the treated animals was principally characterized by

increase in relative liver and thyroid weight and histological findings in these organs (cell 

hypertrophy) and reduced food consumption and decreased body weight gain throughout the 
44

whole study period. Significantly lower number of implantations, significantly increased post 

implantation loss and significantly increased post natal loss in the high dose group of F1 

generation is considered to be the effect of systemic toxicity in maternal animals (body weight 

gain loss, body weight reduction, thyroid enlargement, hepatocellular and thyroid cell 

hypertrophy). Fenpyrazamine showed no effects on fertility. A NOAEL for reproductive effects

was determined at the treatment level of 1000 ppm (73.7 mg/kg bw/d; mean substance intake of 

females of F1 generation during gestation), based on significantly decreased number of 

implantations observed in F1 females at 3000 ppm (which was determined to be the LOAEL of 

the study. A chronic NOAEL value of 1000 will be used to estimate chronic RQs for 

mammals.

 Non-target Beneficial Insects

Two studies were submitted that examined the acute toxicity of fenpyrazamine to the honeybee 

(Apis mellifera). The first study, examined acute oral exposure of bees to fenpyrazamine (94.7% 

a.i) for 48 hours (MRID 48399935). The bees were exposed to nominal doses of 6.3, 13, 25, 50, 

and 100 μg a.i/bee, as well as negative and solvent controls. A maximum of 23.3 % mortality

occurred at the second to highest treatment dose (50 ug a.i/bee) thus yielding an LD50 of >100 μg

a.i/bee. At test termination, a single bee in the 25 μg a.i/bee treatment concentration was 

observed to be lethargic. There were no other clinical signs of toxicity at any treatment 

concentration during the study. This study is classified as supplemental as it does not fulfill any

current OCSPP guideline requirement.

In another study (MRID 48400015), bees were exposed to TGAI fenpyrazamine (94.7%) in an 

acute contact design that included nominal concentrations of 1.9, 4.3, 9.4, 21, 45, and 100 μg 

a.i/bee. After 48 hours, there was a maximum 26.6% mortality that was observed in the highest 

treatment concentration. Clinical signs of toxicity included bees that appeared to be lethargic 

which varied in number depending on the treatment concentration but did follow a dose 

responsive pattern. The LD50 for this study was determined to be >100 μg a.i/bee and the study 

is classified as acceptable.

 Other Non-target Terrestrial Organisms

An acute toxicity study was submitted that exposed TGAI fenpyrazamine to the earthworm 

(Eisenia fetida, MRID 48400025). Earthworms were exposed to nominal concentrations of 25, 

50, 100, 200, 400, and 800 mg a.i/kg dw soil in addition to negative and solvent controls. After a 

14-day exposure, survival ranged from 92.5 to 100%, depending on the treatment concentration. 

Body weight was significantly reduced in all but the lowest treatment concentration as compared 

to the negative control. Lethargy was observed in earthworms exposed to 100 and 800 mg a.i/kg 

dw soil and segmental constriction was observed in earthworms in the 800 mg a.i/kg dw soil 

treatment concentration. The LC50 was determined to be >800 mg a.i/kg dw soil. This study

was scientifically sound but is not designed to fulfill any current OCSPP guideline requirement 

and is therefore classified as supplemental.
45

 Terrestrial Plants

A seedling emergence and vegetative vigor study were submitted with TEP fenpyrazamine 

(44.4% a.i) (MRIDs 48400016 and 48400017, respectively). In the seedling emergence study, 

seeds were exposed to mean measured concentrations ranging from 0.035 to 0.062 lb a.i./A

depending on the species for 21 days. Survival in corn and biomass (weight) in radish and flax 

were significantly affected (p<0.05). The most sensitive monocot species was corn based on 

effects to survival while the most sensitive dicot was flax, based on effects to biomass. In both 

species, the percent inhibition to survival and weight did not exceed? 25% and therefore EC25

values were not definitive. By contrast, there were effects on biomass (weight) to flax in the 

lowest treatment concentration and therefore a definitive NOAEC could not be determined for 

this species. The percent reduction from control in the lowest treatment concentration for flax 

weight was 38.5 while the other percent reductions for this endpoint were 7.9, 11.5, 27.5, and 

30.2 for the lowest to highest treatment concentrations. Although the effects do not follow a 

dose responsive pattern, some chemicals are known to show increased effects at lower 

concentrations. Currently, there is not enough information about fenpyrazamine to definitively

state whether it is among those chemicals yet a 38.5 % effect at the lowest treatment 

concentration is enough of a biological effect to warrant a concern. Phytotoxic effects in this 

study included necrosis, stem curl, and unshed curl. Phytotoxicity signs were infrequent and did 

not appear to be the result of treatment, with the exception of flax and radish which had higher 

and more consistent phytoxicity signs. The most sensitive monocot NOAEC, LOAEC and EC25

was 0.15, 0.30, and >0.60 lbs a.i/A based on survival. The most sensitive dicot NOAEC, 

LOAEC, and EC25 was <0.035, 0.035, and >0.53 lb a.i/A based on biomass (weight). In the 

event that a NOAEC is not definitive, EFED policy is to use the EC05 in its place for estimation 

of RQs. However, despite the model converging, an EC05 was unable be estimated for this 

endpoint. This study is classified as supplemental for this reason as well as since the temperature 

in the test facility ranged from 18 to 38°C (64.4 – 100.4°F) and the relative humidity ranged 

from 14 – 93% during the test. OCSPP guidelines recommend day temperatures of 25 ± 3°C 

(71.6 – 82.4°F) and night temperatures of 20 ± 3 °C (62.6 – 73.4°F) and relative humidity

approaching 70 ± 5 % during light period and 90 % during dark periods. The ranges of 

temperatures and relative humidity for this study are well outside the recommended ranges and 

bring into question either the test facility conditions or the gauges associated with temperature 

and relative humidity equipment. 

In a vegetative vigor study conducted with TEP fenpyrazamine (MRID 48400017), plants were 

exposed to mean measured concentrations of fenpyrazamine ranging from 0.034 to 0.56 lbs a.i/A 

depending on the test species for 21 days. Survival in all species was not significantly affected 

as the percent inhibition as compared to the negative control ranged from 0 to 4.2%. Phytotoxic 

effects in this study included necrosis, leaf curl, stem curl, and unshed seed coat. Overall, the 

seedlings appeared normal throughout the course of the study. Phytotoxic signs were infrequent 

and did not appear to be the result of treatment. There were no significant effects to dry weight 

and height. The NOAEC, LOAEC and EC25 values for the most sensitive dicot species was 0.53, 

>0.53, and >0.53 based on a lack of effects at all treatment concentrations. This study is 

classified as supplemental since the temperature in the test facility ranged from 17 to 32°C (62.6 

– 89.6°F) and the relative humidity ranged from 32 – 95% during the test. OCSPP guidelines 
46

recommend day temperatures of 25 ± 3°C (71.6 – 82.4°F) and night temperatures of 20 ± 3 °C 

(62.6 – 73.4°F) and relative humidity approaching 70 ± 5 % during light period and 90 % during 

dark periods. The ranges of temperatures and relative humidity for this study are well outside 

the recommended ranges and bring into question either the test facility conditions or the gauges 

associated with temperature and relative humidity equipment. For risk assessment purposes, a 

toxicity value of >0.53 lbs a.i/A will be used for estimating risk quotients to non-listed 

terrestrial plants (i.e., a lower bound of 0.53 lbs a.i/A will be used as a screen for toxic 

effects and a toxicity value of <0.035 lbs a.i/A will be used for estimating risk quotients for

listed terrestrial plants (i.e., an upper bound of 0.035 lbs a.i/A will be assumed as a screen 

for toxic effects).

5. PROBLEM FORMULATION

Fenpyrazamine is formulated as a suspension concentrate for foliar ground and aerial spray and 

for spray chemigation. The rate of application for fenpyrazamine ranges from an application rate 

of 0.375 lbs a.i/A to 1.089 lbs a.i/A with maximum number of applications being 3 or 4

depending on the use, and an interval between application of 7 days for all uses. Fenpyrazamine, 

a fungicide, belongs to the pyrazole carboxamide class of fungicides. Other members of this 

family of pesticides include penthiopyrad, penflufen, and sedaxane. Fenpyrazamine’s mode of 

action has not been fully elucidated, but it is thought to inhibit the generation of reproductive 

spores via inhibition of the germ tube and mycelium elongation.8 In addition, pyrazole 

fungicides are known to inhibit the succinate-dehydrogenase enzyme which serves a critical 

mechanism as part of the citric acid cycle and providing a pathway for electronic transfer 

throughout the organism.

9

5.1 Risk Hypotheses 

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in 

assessment endpoints) and may be based on theory and logic, empirical data, mathematical 

models, or probability models (EPA 1998). For fenpyrazamine, the following ecological risk 

hypothesis is being employed for this risk assessment:

Given the proposed ground and aerial foliar spray uses of fenpyrazamine and its 

environmental fate properties, there is a likelihood of exposure to non-target terrestrial 

and aquatic organisms. 

When used in accordance with the label, fenpyrazamine results in potential adverse 

effects upon the survival, growth, and reproduction of non-target terrestrial and aquatic 

organisms. 

 

8 Citation: Footprint database. Accessible on-line: http://sitem.herts.ac.uk/aeru/footprint/en/Reports/2010.htm.

Accessed June 2012.

9 Citation: Fungicide Resistance Action Committee Classification on Mode of Action 2011. Accessible on-line: 

http://www.frac.info/frac/publication/anhang/FRAC%20MoA%20Poster%202011_final_HR.pdf

Accessed August 2012.
47

5.2 Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure.

Fenpyrazamine is considered to be the primary stressor in this risk assessment. Measured 

comprehensive toxicity data for freshwater fish, freshwater invertebrates, and aquatic plants 

indicate that fenpyrazamine is more toxic than the degradates S-2188-OH and S-2188-DC at 

magnitudes surpassing an order of magnitude. Furthermore, ECOSAR indicates that 

fenpyrazamine is overall more toxic than the degradates S-2188-OH, S-2188-DC, MCNI, and the 

S-2188-DC conjugate. The only exception is that the S-2188-DC conjugate is estimated to be 

more toxic than parent fenpyrazamine for green algae. However, no exposure of green algae to 

the S-2188-DC conjugate is expected since the S-2188-DC conjugate is only found to 

bioconcentrate in fish tissue. A summary of the measured and estimated endpoints comparing 

fenpyrazamine and the degradates can be found in Appendix G.

The environmental fate properties of fenpyrazamine indicate that dietary exposure to 

terrestrial organisms, exposure to terrestrial plants, and aquatic exposure are relevant 

paths of exposure associated with pesticide applications. Direct deposition of fenpyrazamine

sprays, runoff, leaching, and spray drift deposition represent potential transport mechanisms to 

aquatic and terrestrial organisms. The movement away from the site of application in turn 

represents exposure pathways for a broad range of biological receptors of concern (non-target 

animals) and the potential attribute changes, i.e., effects such as reduced survival, growth and 

reproduction, in the receptors due to fenpyrazamine exposure. Terrestrial animals may be 

exposed to fenpyrazamine by intentionally or inadvertently ingesting residues on treated crops. 

They also may be exposed by other routes, such as by walking on residues or drinking water 

contaminated by residues. Based on the nature of fenpyrazamine applications, as well as 

fenpyrazamine’s moderate persistence and mobility in the environment, dietary exposure to 

terrestrial exposure and aquatic exposure from fenpyrazamine applications will be assessed. 

Furthermore, given fenpyrazamine’s tendency to bind to soil and sediment (as evidenced by the 

spiked water sediment toxicity study conducted with Chironomus riparius, MRID 48400007) , 

risks to bottom-dwelling organisms residing in the benthos as well as organisms which feed on 

sediment will be assessed.

Bioaccumulation of fenpyrazamine residues is not expected to be significant in fish. As 

stated in Section 3, despite fenpyrazamine’s high Kow value and expected bioconcentration, 

steady-state BCF values in fish are low (MRID No. 48400005)10. In addition, fenpyrazamine is

transformed rapidly to S-2188-DC and S-2188-DC conjugate in fish tissue. Depuration of the 

metabolites detected in fish tissues is also rapid.

 

10 BCF study conducted on bluegill sunfish.
48

Drinking water and inhalation exposure to terrestrial animals are not expected to be of 

concern according to the results of the Screening Imbibition Program (SIP version 1.0, 

6/15/2010) and the Screening Tool for Inhalation Risk (STIR version 1.0; 11/23/2010), 

respectively. SIP is available publically at: 

http://www.epa.gov/oppefed1/models/terrestrial/sip/sip_user_guide.html. STIR may be accessed 

on-line at: http://www.epa.gov/oppefed1/models/terrestrial/stir/stir_user_guide.html. The output 

files for STIR and SIP can be found in Appendices B and C, respectively. 

5.3 Analysis Plan 

The primary method used to assess risk in this screening-level assessment is the risk quotient 

(RQ) and follows the methods outlined in the EPA Overview Document (EPA, 2004). The RQ 

is the primary risk value for the screening-level assessment and is the result of comparing 

measures of exposure to measures of effect. A commonly used measure of exposure is the 

estimated exposure concentration (EEC) and commonly used measures of effect include toxicity

values such as the LD50 or NOAEC. The RQ is calculated as a ratio of the estimated 

environmental concentration (EEC) to an effect level (e.g., LC50, LD50 or NOAEC) using the 

effect level as a denominator. The resulting RQ is then compared to a specified level of concern 

(LOC), which represents a point of departure for concern. For example, if the RQ exceeds the 

LOC, then there is the potential for risk. In general, the higher the RQ, the more certain the 

potential risks. However, the risk quotients are not necessarily a true estimate of risk since there 

is no estimated probability of effect. Risk presumptions, along with the corresponding RQs and 

LOCs, are summarized in Appendix A.

Generation of robust risk quotients is dependent on the quality of data from both fate and 

toxicological studies. The adequacy of the submitted data is evaluated relative to Agency

guidelines. For fenpyrazamine, the available ecological effects data is determined to be 

sufficient in evaluating the ecological risk to terrestrial and aquatic organisms as a result of the 

proposed uses.

5.3.1 Measures of Exposure 

Measures of exposure are estimates of exposure for a receptor determined by modeling or 

monitoring data. Measures of exposure for fenpyrazamine in this assessment are obtained from 

modeling efforts only, since this is a new chemical and national-scale monitoring data is not

available. Exposure models used for this assessment include the suite of standard exposure 

models commonly used in pesticide risk assessments (EPA, 2004). Generally, aquatic exposure 

estimates are generated from EFED models.

To estimate risks of fenpyrazamine exposures in aquatic and terrestrial environments, all 

exposure modeling and resulting risk conclusions will be based on maximum application rates 

and methods cited in Table 1and will be estimated for each use of fenpyrazamine. Measures of 

exposure are based on aquatic and terrestrial models that predict estimated environmental 

concentrations (EEC) of halofenozide. The models used to predict surface water, benthic, and 

sediment aquatic EECs are the Pesticide Root Zone Model coupled with the Exposure Analysis 
49

Modeling System (PRZM/EXAMS) publically available at: 

http://www.epa.gov/oppefed1/models/water/pe5_user_manual.htm. The PRZM/EXAMS 

standard farm pond scenario will be used to estimate the aquatic EECs. The model used to 

predict terrestrial EECs on food items is the Terrestrial Residue Exposure (T-REX) publically 

available at: http://www.epa.gov/oppefed1/models/terrestrial/trex/t_rex_user_guide.htm. The 

model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant accessible 

publically at: 

http://www.epa.gov/oppefed1/models/terrestrial/terrplant/terrplant_user_guide.html. These 

models are parameterized using relevant reviewed environmental fate data and ecological 

toxicity studies from registrant submissions and the literature; model input values will be 

consistent with the most recent version of the input parameter guidance (citation: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm)).

5.3.2 Measures of Effects 

Measures of ecological effects are obtained from a suite of registrant-submitted guideline studies 

conducted with a limited number of surrogate species. Measures of effect are based on 

deleterious changes in an organism as a result of chemical exposure. Functionally, measures of 

effect typically used in risk assessments include changes in survival, reproduction, or growth as 

determined from standard laboratory toxicity tests. The focus on these effects for quantitative 

risk assessment is due to their clear relationship to higher-order ecological systems such as 

populations, communities, and ecosystems. Although monitoring data may also be used to 

provide supporting lines of evidence for the risk characterization, monitoring data is not 

available for this new chemical. Commonly used laboratory-derived toxicity values include 

estimates of acute mortality (such as LD50, LC50, or EC50) and estimates of effects due to longer 

term, chronic exposures (such as the NOAEC or NOAEL). In addition, effects other than 

survival, reproduction, and growth may be considered, (such as changes in biochemical, cellular, 

organ-level responses) but are typically used qualitatively to characterize risks since, in many 

cases, the relationship between these effects and higher-order processes is prone to more 

uncertainty. The latter can reflect changes seen in mortality, reproduction, or growth. In 

general, for a given assessment endpoint, the lowest relevant measure of effect is used in 

calculating the risk quotient.

5.3.3 Integration of Exposure and Effects

The assessment endpoints can be summarized as survival, growth, and reproduction of terrestrial 

and aquatic receptors to include birds, mammals, reptiles, amphibian, fish, terrestrial and aquatic 

invertebrates and terrestrial and aquatic plants. The response of these receptors to fenpyrazamine

exposure is represented by a small number of toxicity studies on representative or surrogate 

species. Hence, there is considerable uncertainty regarding the response of a receptor since data 

for all species potentially exposed are not available. The lowest available measure of effect for a 

given assessment endpoint is used to calculate risk to accommodate for some of this inherent 

uncertainty. 

The ecosystems selected for modeling using PRZM/EXAMS aquatic assessment and T-REX for 

the terrestrial animal assessment are intended to be generally representative of any aquatic or 
50

terrestrial ecosystem associated with areas where fenpyrazamine is used. The receptors 

addressed by the aquatic and terrestrial risk assessments for fenpyrazamine are summarized in

Table 5. For aquatic assessments, generally fish and aquatic invertebrates in both freshwater and 

estuarine/marine environments are represented. For terrestrial assessments, three different size 

classes of small mammals are represented, along with five potential foraging categories (short 

grass, tall grass, broadleaf plants, fruits/pods/seed and arthropods). For the three different size 

classes of birds, the same five potential foraging categories are also considered (short grass, tall 

grass, broadleaf plants, fruits/pods/seeds, and arthropods). In addition, data are available so that 

earthworms, terrestrial non-target insects, and sediment-dwelling organisms are represented. 

6. EXPOSURE ANALYSIS

6.1 Aquatic Exposure

Tier II Estimated Environmental Concentrations (EECs) were estimated using EFED’s aquatic 

models PRZM (Pesticide Root Zone Model) version 3.12 (dated May 2005) and EXAMS 

(Exposure Analysis Modeling System) version 2.98.4.6 (dated April 2005). PRZM is used to 

simulate pesticide transport as a result of runoff, erosion, and spray drift from a 10-ha 

agricultural field, and EXAMS considers environmental fate and transport of pesticides in 

surface water and predicts EECs in a standard farm pond (10,000-m

2

pond, 2-m deep), with the 

assumption that the small field is cropped at 100%. Simulations are carried out with the linkage 

program shell, PE5.pl (dated 11/15/06), which incorporates the standard crop and orchard

scenarios developed by EFED. Table 10 shows the PRZM/EXAMS environmental fate input 

parameter values and related justifications.

Table 10. Summary of PRZM/EXAMS input parameter values for physical chemical and fate 

properties used for fenpyrazamine surface water aquatic EECs.

PRZM/EXAMS Input Parameter Input Value and Unit Source

Physical Chemical Properties

Molecular Weight 331.4 g/mol MRID 48399906

Solubility in Water 20.4 mg/L MRID 48399915

Vapor Pressure 2.17 x 10-10 torr MRID 48399916

Henry’s Law Constant 2.28 x 10-10 atm·m3

/mol EpiSuite 

HENRYWIN v. 3.20

Environmental Fate Properties

Soil-Water Partition Coefficient (Kd) 5.06 mL/g MRID 48399919

MRID 48399922

Average of Kd values from 

UK Clay Loam (8.7 mL/g), 

UK Silt Loam (7.4 mL/g), UK 

Loam (4.2 mL/g), UK Loamy 

Sand (5.7 mL/g), NJ Silt Loam 

(366 mL/g) and CA Loamy 

Sand (585 mL/g) 1

Hydrolysis (t1/2) pH4: Stable

pH7: Stable

pH9: 10.9 days

MRID No. 48399923

Conservative default for pH72
51

Table 10. Summary of PRZM/EXAMS input parameter values for physical chemical and fate 

properties used for fenpyrazamine surface water aquatic EECs.

PRZM/EXAMS Input Parameter Input Value and Unit Source

Aqueous Photolysis (t1/2) 1.64 days MRID 48399924

Aerobic soil metabolism (t1/2) 478.09 days MRID 48399919 3

MRID 48399928 4

Aerobic aquatic metabolism (t1/2) 551 days Upper 90th percentile4of 

values from MRID 48399929 

(18.93 and 280 days, water 

and sediment total system)

Anaerobic aquatic metabolism (t1/2) 36.6 days EFED Input Parameter 

Guidance for one valid study 

(12.2 days x 3 based on water 

and sediment total system)

1

 Information unavailable related to the representativeness of UK Clay Loam, UK Silt Loam, UK Loam, UK Loamy 

Sand, and Japan Sandy Loam soils to domestic soils. However, the UK soils were used since soils traditionally 

possess physical chemical characteristics similar to US soils. Japan Sandy Loam soil not used since soils 

traditionally possess volcanic minerals not found widely within US soils. 

2

 Environmentally relevant half-lives could not be determined for pH7. Hydrolysis half lives at 25°C could not be 

determined from pH 7.

3

 Information unavailable related to the representativeness of UK Loam, UK Silt Loam, and two UK Sandy Loam 

soils to domestic soils. However, the UK soils were used since soils traditionally possess physical chemical 

characteristics similar to US soils. 

4

 The upper 90th percentile half life calculated as follows: t1/2 input = /

 + (t90, n-1 x σ)

 n

1/2

where /

 is the mean of the set of half lives from each study, t90, n-1 is the one-sided t value for the 90th percentile 

level, σ is the standard deviation of the set of half lives determined from each study, and n is the sample size of the 

set of half lives determined from each study.

All crops and application methods proposed on the label for fenpyrazamine were considered in 

this assessment. Various scenarios, where available, were simulated for specific crops to account 

for different geographical locations agricultural practices. Many crop scenarios are available to 

directly address the crops listed on the label. However, surrogate scenarios were selected in a 

few cases in the PRZM/EXAMS modeling approach. For example, the NY Grape scenario is a 

surrogate for the bushberries and caneberries proposed uses. The maximum application rates, 

minimum retreatment intervals, and number of applications specified on the label for grapes are 

identical to bushberries and caneberries. In addition, the MN Sugarbeets and MI Asparagus crop 

scenarios were used as a surrogate to represent fenpyrazamine proposed used on ginseng. 

Consistent with the label, ground and aerial applications were modeled for each crop. The 

PRZM-EXAMS crop specific environmental inputs used in each crop surrogate for each new 

proposed treatment is shown in Table 11.
52

Table 11. Crop management PRZM/EXAMS inputs used in aquatic exposure 

modeling.

PRZM/EXAMS 

Input Parameter

Input Value and Unit Comment

Labeled Crop, Crop 

Scenarios, 

Application Rate, 

Number of 

Applications, 

Retreatment Time 

Interval, and

Application Date 

Almonds and Pistachio

CA Almond

 Application Rate: 0.420 kg/ha

 3 applications per season

 7 days between applications

 Application Date: Jan. 20

Application dates 

conservatively selected 

based on maximum 

rainfall climatological 

date at meteorological 

station defined in each 

crop scenario site after 

crop emergence date 

specified in PRZM crop 

scenario.

Lettuce

CA Lettuce

 Application Rate: 0.560 kg/ha

 3 applications per season

 7 days between applications

 Application Date: Feb. 25

Grapes, Bushberries, and Caneberries

NY Grape

 Application Rate: 0.560 kg/ha

 3 applications per season

 7 days between applications

 Application Date: Sept. 10

Strawberries

FL Strawberry

 Application Rate: 0.560 kg/ha

 4 applications per season

 7 days between applications

 Application Date: Oct. 5

Ginseng

MN Sugarbeet

 Application Rate: 0.560 kg/ha

 4 applications per season

 7 days between applications

 Application Date: June 20

MI Asparagus

 Application Rate: 0.560 kg/ha

 4 applications per season

 7 days between applications

 Application Date: August 1
53

Table 11. Crop management PRZM/EXAMS inputs used in aquatic exposure 

modeling.

PRZM/EXAMS 

Input Parameter

Input Value and Unit Comment

Ornamentals

MI Nursery

 Application Rate: 1.22 kg/ha

 3 application per season

 7 days between applications

 Application Date: Aug. 1

NJ Nursery

 Application Rate: 1.22 kg/ha

 3 application per season

 7 days between applications

 Application Date: Aug. 1

TN Nursery

 Application Rate: 1.22 kg/ha

 3 application per season

 7 days between applications

 Application Date: Aug. 1

Chemical 

Application Method 

Aerial and Ground Applications

CAM = 2, linear foliar based on crop canopy

Application 

Efficiency

Aerial Applications = 0.95

Ground Applications = 0.99

EFED Model Input 

Parameter Guidance 

Spray Drift Fraction Aerial Applications = 0.05

Ground Applications = 0.01

Surface water one-in-ten year upper bound EECs for all scenarios are presented in Table 12 and

Table 13 for aerial and ground applications, respectively. Examples of the PRZM/EXAMS

input and output files are in Appendix E. As expected, EECs from aerial applications are higher 

than ground applications with peak acute EECs ranging between 10.21 – 86.60 μg /L, 21-day

EECs ranging between 9.80 – 83.92 μg/L, and 60-day chronic average EECs ranging between

9.23 – 80.35 μg/L amongst all of the crop scenarios. For ground applications, EECs are 

generally slightly lower than aerial applications with peak acute EECs ranging between 7.41 –

81.22 μg /L, 21-day EECs ranging between 7.34 – 78.70 μg/L, and 60-day chronic average EECs 

ranged from 6.88 – 75.18 μg/L. It is important to note that concentrations of fenpyrazamine are 

not reduced significantly over larger averaging periods. Please refer to Section 7.2.6.b for 

further details related to the uncertainties accounted for which contribute to this result.

One-in-ten year upper bound benthic pore water EECs from PRZM/EXAMS for all scenarios are 

presented in Table 14 and Table 15 for aerial and ground applications, respectively. 

Fenpyrazamine EECs in benthic water pores were generally half of the values in surface water. 

For aerial applications, peak acute EECs range between 5.92 – 47.17 μg /L, 21-day EECs range

between 5.26 – 46.79 μg/L, and 60-day chronic average EECs range between 5.15 – 46.05 μg/L

amongst all of the crop scenarios. For ground applications, EECs are lower than aerial 

applications consistent to water column EECs with peak acute EECs ranging between 3.95 –
54

44.27μg /L, 21-day EECs ranging between 3.93 – 43.92 μg/L, and 60-day chronic average EECs 

ranged from 3.86 – 43.23 μg/L. The modeling results for benthic water pores also do not change 

significantly with time. Please refer to Section 7.2.6.b for further details related to a further 

characterization of these results and the uncertainties accounted for which contribute to this 

result.

One-in-ten year upper bound sediment EECs from EXAMS are presented in Table 16 and Table 

17 for aerial and ground applications, respectively. As expected, and consistent with other 

compartments, sediment concentrations resulting from aerial applications are slightly higher than 

sediment concentrations resulting from ground applications. Furthermore, average 

concentrations do not change significantly over time. EECs in sediment for aerial and ground 

applications range between 0.03 – 0.25 mg/kg over all acute and chronic exposure durations. 

The concentrations in sediment are expected given fenpyrazamine’s tendency to adsorb to soil 

and sediment given its moderate Koc values. Furthermore, EXAMS assumes that sediment 

concentrations are in equilibrium with water pore concentrations. Therefore, sediment 

concentrations are inter-related to benthic water pore concentrations. Please refer to Section 

7.2.6.b for further details related to the uncertainties accounted for in this modeling which 

influence the slow decline observed in the modeled residues in the sediment and benthic water 

pore compartments over time.

Table 12. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

surface water (ppb) for aerial applications of fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 10.21 9.80 9.23

Lettuce CA Lettuce 30.51 29.49 28.08

Grapes

Bushberries

Caneberries

NY Grape 25.61 24.96 23.95

Strawberries FL Strawberry 30.92 29.59 26.84

Ginseng MN Sugarbeet 42.65 41.03 38.76

MI Asparagus 14.30 13.85 13.58

Ornamentals MI Nursery 61.92 60.80 59.69

NJ Nursery 86.60 83.92 80.35

TN Nursery 44.67 43.50 41.19

*Bold text indicate maximum values.
55

Table 13. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

surface water (ppb) for ground applications of fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 7.41 7.34 6.88

Lettuce CA Lettuce 27.60 26.60 25.45

Grapes

Bushberries

Caneberries

NY Grape 21.73 21.20 20.26

Strawberries FL Strawberry 27.42 26.23 23.65

Ginseng MN Sugarbeet 37.50 36.14 34.27

MI Asparagus 9.98 9.89 9.70

Ornamentals MI Nursery 56.43 55.98 54.99

NJ Nursery 81.22 78.70 75.18

TN Nursery 38.41 37.30 35.21

*Bold text indicate maximum values.

Table 14. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

benthic pore water (ppb) for aerial applications of fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 5.29 5.26 5.15

Lettuce CA Lettuce 15.28 15.25 15.01

Grapes

Bushberries

Caneberries

NY Grape 15.78 15.75 15.58

Strawberries FL Strawberry 13.22 13.19 13.04

Ginseng MN Sugarbeet 23.13 23.07 22.91

MI Asparagus 10.63 10.57 10.44

Ornamentals MI Nursery 38.43 38.20 37.12

NJ Nursery 47.17 46.79 46.05

TN Nursery 23.32 23.24 22.52

*Bold text indicate maximum values.
56

Table 15. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

benthic pore water (ppb) for ground applications of fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 3.95 3.93 3.86

Lettuce CA Lettuce 13.92 13.89 13.67

Grapes

Bushberries

Caneberries

NY Grape 13.57 13.56 13.37

Strawberries FL Strawberry 11.55 11.53 11.42

Ginseng

MN Sugarbeet 20.62 20.60 20.47

MI Asparagus 7.66 7.61 7.51

Ornamentals

MI Nursery 34.30 34.08 33.03

NJ Nursery 44.27 43.92 43.23

TN Nursery 20.00 19.94 19.40

*Bold text indicate maximum values.

Table 16. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

sediment (mg fenpyrazamine/kg sediment, dry weight) for aerial applications of 

fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 0.03 0.03 0.03

Lettuce CA Lettuce 0.08 0.08 0.08

Grapes

Bushberries

Caneberries

NY Grape 0.09 0.09 0.09

Strawberries FL Strawberry 0.07 0.07 0.07

Ginseng MN Sugarbeet 0.13 0.13 0.12

MI Asparagus 0.06 0.06 0.06

Ornamentals MI Nursery 0.21 0.21 0.20

NJ Nursery 0.26 0.25 0.25

TN Nursery 0.13 0.13 0.12

*Bold text indicate maximum values.
57

Table 17. PRZM/EXAMS estimated one-in-ten year upper bound concentrations in 

sediment (mg fenpyrazamine/kg sediment, dry weight) for ground applications of 

fenpyrazamine.

Crops

PRZM Crop 

Scenario

Peak

(Acute)

21 Day Average 

(Acute)

60-Day Average 

(Chronic)

Almonds

Pistachios

CA Almond 0.02 0.02 0.02

Lettuce CA Lettuce 0.08 0.08 0.07

Grapes

Bushberries

Caneberries

NY Grape 0.07 0.07 0.07

Strawberries FL Strawberry 0.06 0.06 0.06

Ginseng

MN Sugarbeet 0.11 0.11 0.11

MI Asparagus 0.04 0.04 0.04

Ornamentals

MI Nursery 0.19 0.19 0.18

NJ Nursery 0.24 0.24 0.24

TN Nursery 0.11 0.11 0.11

Bold text indicate maximum values.

6.2 Terrestrial Exposure

In order to estimate risks of fenpyrazamine exposures in terrestrial environments, all exposure 

modeling and resulting risk conclusions will be based on maximum application rates for a given 

use. Measures of exposure are based on aquatic and terrestrial models that predict estimated 

environmental concentrations (EECs) of fenpyrazamine. 

6.2.1 Wildlife Dietary Exposure

Exposure estimates for terrestrial animals assumed to be in the target area or in an area exposed 

to spray drift are derived from using the T-REX model (Version 1.5, released 03/2012). This 

model incorporates the Kenaga nomogram, as modified by Fletcher et al. (1994), which is based 

on a large set of actual field residue data. The upper limit values from the nomograph 

represented the 95th percentile of residue values from actual field measurements (Hoerger and 

Kenaga, 1972). The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on 

field measured field residues from 249 published papers, including information on 118 species of 

plants, 121 pesticides, and 17 chemical classes. The default environmental half life of 35 days is 

used to estimate EECs. Table 18 and Table 19 show the estimated environmental 

concentrations (EECs) for the three weight classes of birds and mammals, respectively.
58

Table 18. Terrestrial food item residue estimates for birds with proposed fenpyrazamine 

uses on various crops.

20-gram

bird

100-gram

bird

1000-gram

bird

All weight classes 

(bird)

Proposed use Food Item Maximum Dose-Based EECs (mg/kgbw)

Dietary-based EEC 

(ppm)

Almonds, pistachios

Short grass 265.82 151.58 67.87 233.40

Tall grass 121.84 69.48 31.11 106.98

Broadleaf plants 149.53 85.27 38.17 131.29

Fruits/pods/seeds 16.61 9.47 4.24 14.59

Arthropods 104.11 59.37 26.58 91.42

Lettuce

Short grass 352.03 200.75 89.88 309.10

Tall grass 161.35 92.01 41.19 141.67

Broadleaf plants 198.02 112.92 50.56 173.87

Fruits/pods/seeds 22.00 12.55 5.62 19.32

Arthropods 137.88 78.63 35.20 121.06

Grapes, bushberries, 

caneberries

Short grass 352.03 200.75 89.88 309.10

Tall grass 161.35 92.01 41.19 141.67

Broadleaf plants 198.02 112.92 50.56 173.87

Fruits/pods/seeds 22.00 12.55 5.62 19.32

Arthropods 137.88 78.63 35.20 121.06

Strawberries

Short grass 440.40 251.13 112.44 386.69

Tall grass 201.85 115.10 51.53 177.23

Broadleaf plants 247.72 141.26 63.25 217.51

Fruits/pods/seeds 27.52 15.70 7.03 24.17

Arthropods 172.49 98.36 44.04 151.45

Ginseng 

Short grass 440.40 251.13 112.44 386.69

Tall grass 201.85 115.10 51.53 177.23

Broadleaf plants 247.72 141.26 63.25 217.51

Fruits/pods/seeds 27.52 15.70 7.03 24.17

Arthropods 172.49 98.36 44.04 151.45

Ornamentals 

Short grass 768.73 438.36 196.26 674.98

Tall grass 352.33 200.92 89.95 309.36

Broadleaf plants 432.41 246.58 110.40 379.67

Fruits/pods/seeds 48.05 27.40 12.27 42.19

Arthropods 301.09 171.69 76.87 264.37

Table 19. Terrestrial food item residue estimates for mammals with proposed 

fenpyrazamine uses on various crops.

15-gram

mammal

35-gram

mammal

1000-gram

mammals

All weight classes 

(mammal)

Proposed use Food Item Maximum Dose-Based EECs (mg/kg-bw) Dietary-based 

EEC (ppm)

Almonds, pistachios

Short grass 222.53 153.80 35.66 233.40

Tall grass 101.99 70.49 16.34 106.98

Broadleaf plants 125.17 86.51 20.06 131.29

Fruits/pods/seeds 13.91 9.61 2.23 14.59

Arthropods 87.16 60.24 13.97 91.42

Lettuce

Short grass 294.70 203.68 47.22 309.10

Tall grass 135.07 93.35 21.64 141.67

Broadleaf plants 165.77 114.57 26.56 173.87

Fruits/pods/seeds 18.42 12.73 2.95 19.32
59

Table 19. Terrestrial food item residue estimates for mammals with proposed 

fenpyrazamine uses on various crops.

15-gram

mammal

35-gram

mammal

1000-gram

mammals

All weight classes 

(mammal)

Proposed use Food Item Maximum Dose-Based EECs (mg/kg-bw) Dietary-based 

EEC (ppm)

Arthropods 115.43 79.77 18.50 121.06

Grapes, bushberries, 

caneberries

Short grass 294.70 203.68 47.22 309.10

Tall grass 135.07 93.35 21.64 141.67

Broadleaf plants 165.77 114.57 26.56 173.87

Fruits/pods/seeds 18.42 12.73 2.95 19.32

Arthropods 115.43 79.77 18.50 121.06

Strawberries

Short grass 368.68 254.81 59.08 386.69

Tall grass 168.98 116.79 27.08 177.23

Broadleaf plants 207.38 143.33 33.23 217.51

Fruits/pods/seeds 23.04 15.93 3.69 24.17

Arthropods 144.40 99.80 23.14 151.45

Ginseng 

Short grass 368.68 254.81 59.08 386.69

Tall grass 168.98 116.79 27.08 177.23

Broadleaf plants 207.38 143.33 33.23 217.51

Fruits/pods/seeds 23.04 15.93 3.69 24.17

Arthropods 144.40 99.80 23.14 151.45

Ornamentals 

Short grass 643.54 444.77 103.12 674.98

Tall grass 294.95 203.85 47.26 309.36

Broadleaf plants 361.99 250.18 58.01 379.67

Fruits/pods/seeds 40.22 27.80 6.45 42.19

Arthropods 252.05 174.20 40.39 264.37

6.2.2 Terrestrial Plant Exposure

The model used to predict terrestrial and wetland plants is TerrPlant (version 1.2.2, released 

12/2006). EECs for terrestrial plants inhabiting dry and wetland areas are derived using this 

model which utilizes the solubility of pesticide in runoff and in spray drift. Additionally, 

TerrPlant derived EECs factor in application rate and minimum incorporation depth. Table 20

summarizes the EECs resulting from the proposed uses of fenpyrazamine.

Table 20. TerrPlant derived EECs for dry and semi-aquatic areas resulting from proposed 

fenpyrazamine uses.

Crop

Single Max Application 

Rate (lbs a.i/A)

Description of Area

EEC

(lbs a.i/A

Almonds, Pistachios 0.37 

Runoff to Dry areas 0.007

Runoff to semi-aquatic areas 0.07

Spray drift 0.02

Total for dry areas 0.03

Total for semi-aquatic areas 0.09

Lettuce, Grapes, Bushberries, 0.49 Runoff to Dry areas 0.01
60

Table 20. TerrPlant derived EECs for dry and semi-aquatic areas resulting from proposed 

fenpyrazamine uses.

Crop

Single Max Application 

Rate (lbs a.i/A)

Description of Area

EEC

(lbs a.i/A

Caneberries, Strawberries, 

Ginseng

Runoff to semi-aquatic areas 0.10

Spray drift 0.02

Total for dry areas 0.3

Total for semi-aquatic areas 0.12

Ornamentals 1.07

Runoff to Dry areas 0.02

Runoff to semi-aquatic areas 0.02

Spray drift 0.05

Total for dry areas 0.07

Total for semi-aquatic areas 0.27

7. RISK CHARACTERIZATION

Risk characterization is the integration of exposure and effects characterization to determine the 

ecological risk from the use of fenpyrazamine and the likelihood of effects on aquatic life, 

wildlife, and plants based on varying pesticide-use scenarios. The risk characterization provides 

estimation and a description of the risk; articulates risk assessment assumptions, limitations, and 

uncertainties; synthesizes an overall conclusion; and provides the risk managers with information 

to make regulatory decisions.

7.1 Risk Estimation - Integration of Exposure and Effects Data 

Results of the exposure and toxicity effects data are used to evaluate the likelihood of adverse 

ecological effects on non-target species. For the assessment of fenpyrazamine risks, the risk 

quotient method is used to compare exposure and measured toxicity values (refer to Appendix 

E). Estimated environmental concentrations are divided by the most sensitive acute and chronic 

toxicity values. The RQs are then compared to the Agency’s levels of concern. These LOCs, 

summarized in Appendix E, are the Agency’s interpretive policy and are used to analyze 

potential risk to non-target organisms and the need to consider regulatory action. These criteria 

are used to indicate when a pesticide’s use as directed on the label has the potential to cause 

adverse effects on non-target organisms. 

7.1.1 Non-target Aquatic Animals and Plants 

To assess risk of fenpyrazamine to non-target aquatic animals and plants, surface water, pore 

water and sediment EECs for fenpyrazamine were obtained from the Tier 2 model 

PRZM/EXAMS based on the label-recommended usage scenarios Table 3
61

a. Water Column Exposure: Acute and Chronic Risk to Animals 

 Fish

Maximum acute and chronic RQs for freshwater and estuarine/marine fish are determined from 

the peak and 60-d average EECs and the appropriate toxicity reference values (Table 7). Table 

21 summarizes the acute and chronic RQs for freshwater and estuarine/marine fish in the water 

column with the EECs and toxicological endpoints that they were derived from. For 

estuarine/marine fish, both the most sensitive acute and chronic endpoints were non-definitive. 

In the case of acute exposure, a 96-hr LC50 of >3900 μg a.i/L (>3.9 mg a.i/L) was determined 

and therefore resultant RQs would also be non-definitive but represent the greatest measure of 

risk for a given application method on a given crop. For example, a peak EEC of 30 μg a.i/L and 

a 96-hr LC50 of >3900 μg a.i/L would yield an RQ of <0.008, that is, the RQ for this use would 

be at most 0.008 but how far it actually falls below that value is an uncertainty. Conversely, for 

chronic exposure to estuarine/marine fish, a NOAEC value was determined to be <39 μg a.i/L

and therefore resultant RQs would also be non-definitive but represent the lowest measure of risk 

for a given application method on a given crop. For example a 60-day EEC of 20 μg a.i/L and a 

NOAEC value of <39 μg a.i/L would yield an RQ of >0.51, that is, the RQ for this use would be 

at least 0.51, but how far it actually falls above that value is an uncertainty. 

For freshwater fish, acute RQs ranged from 0.001 (ground applications to almonds and 

pistachios) to 0.017 (aerial applications for ornamentals), all below the acute endangered species, 

acute restricted use, and acute non-listed species LOCs. Chronic RQs ranged from 0.02 (ground 

application to almonds and pistachios) to 0.22 (aerial application to ornamentals), which are all

below the chronic risk LOC of 1.

For estuarine/marine fish, acute and chronic RQs resulted from non-definitive toxicity endpoints 

and therefore the actual RQs are not known with certainty. The uncertainty in these upper and 

lower bound RQs are discussed further in the Risk Description, Section 7.2.1.
62

Table 21. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to 

freshwater and estuarine/marine fish. 

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EEC

Peak

(μg 

a.i./L)

EEC

60-Day

(μg 

a.i./L)

LC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Acute RQ 

(Peak 

EEC/LC50)

Chronic

RQ

(60-day 

EEC/NOAEC)

Almonds

(CA 

Almond)

Freshwater fish Aerial 10.21 9.23 5200 370 0.002 0.02

Ground 7.41 6.88 0.001 0.02

Estuarine/marine 

fish

Aerial 10.21 9.23 >3900 <39 <0.003 >0.24

Ground 7.41 6.88 <0.002 >0.18

Pistachios

(CA 

Almond)

Freshwater fish Aerial 10.21 9.23 5200 370 0.002 0.02

Ground 7.41 6.88 0.001 0.02

Estuarine/marine 

fish

Aerial 10.21 9.23 >3900 <39 <0.003 >0.24

Ground 7.41 6.88 <0.002 >0.18

Lettuce

(CA 

Lettuce)

Freshwater fish Aerial 30.51 28.08 5200 370 0.006 0.08

Ground 27.6 25.45 0.005 0.07

Estuarine/marine 

fish

Aerial 30.51 28.08 >3900 <39 <0.008 >0.72

Ground 27.6 25.45 <0.007 >0.65

Grapes

(NY 

Grapes)

Freshwater fish Aerial 25.61 23.95 5200 370 0.005 0.06

Ground 21.73 20.26 0.004 0.05

Estuarine/marine 

fish

Aerial 25.61 23.95 >3900 <39 <0.007 >0.61

Ground 21.73 20.26 <0.006 >0.52

Bushberries 

(NY 

Grapes) 

Freshwater fish Aerial 25.61 23.95 5200 370 0.005 0.06

Ground 21.73 20.26 0.004 0.05

Estuarine/marine 

fish

Aerial 25.61 23.95 >3900 <39 <0.007 >0.61

Ground 21.73 20.26 <0.006 >0.52

Caneberries 

(NY 

Grapes)

Freshwater fish Aerial 25.61 23.95 5200 370 0.005 0.06

Ground 21.73 20.26 0.004 0.05

Estuarine/marine 

fish

Aerial 25.61 23.95 >3900 <39 <0.007 >0.61

Ground 21.73 20.26 <0.006 >0.52

Strawberries

(FL 

Strawberry)

Freshwater fish Aerial 30.92 26.84 5200 370 0.006 0.07

Ground 27.42 23.65 0.005 0.06

Estuarine/marine 

fish

Aerial 30.92 26.84 >3900 <39 <0.008 >0.69

Ground 27.42 23.65 <0.007 >0.61

Ginseng 

(MN 

Sugarbeet)

Freshwater fish Aerial 42.65 38.76 5200 370 0.008 0.10

Ground 37.5 34.27 0.007 0.09

Estuarine/marine 

fish

Aerial 42.65 38.76 >3900 <39 <0.011 >0.99

Ground 37.5 34.27 <0.010 >0.88

Ginseng 

(MI 

Asparagus)

Freshwater fish Aerial 14.3 13.58 5200 370 0.003 0.04

Ground 9.98 9.7 0.002 0.03

Estuarine/marine 

fish

Aerial 14.3 13.58 >3900 <39 <0.004 >0.35

Ground 9.98 9.7 <0.003 >0.25

Ornamentals

(MI 

Nursery)

Freshwater fish Aerial 61.92 59.69 5200 370 0.012 0.16

Ground 56.43 54.99 0.011 0.15

Estuarine/marine 

fish

Aerial 61.92 59.69 >3900 <39 <0.016 >1.53

Ground 56.43 54.99 <0.014 >1.41

Ornamentals

(NJ 

Nursery)

Freshwater fish Aerial 86.6 80.35 5200 370 0.017 0.22

Ground 81.22 75.18 0.016 0.20

Estuarine/marine 

fish

Aerial 86.6 80.35 >3900 <39 <0.022 >2.06

Ground 81.22 75.18 <0.021 >1.93

Ornamentals

(TN 

Nursery)

Freshwater fish Aerial 44.67 41.19 5200 370 0.009 0.11

Ground 38.41 35.21 0.007 0.10

Estuarine/marine 

fish

Aerial 44.67 41.19 >3900 <39 <0.011 >1.06

Ground 38.41 35.21 <0.010 >0.90
63

Table 21. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to 

freshwater and estuarine/marine fish. 

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EEC

Peak

(μg 

a.i./L)

EEC

60-Day

(μg 

a.i./L)

LC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Acute RQ 

(Peak 

EEC/LC50)

Chronic

RQ

(60-day 

EEC/NOAEC)

Bolded values represent LOC exceedances.

LOCs are: acute endangered species = 0.05; acute restricted use = 0.1; acute high risk = 0.5; chronic risk = 1

 Aquatic Invertebrates-Water Column

Maximum acute and chronic RQs for aquatic invertebrates are determined from the peak and 21-

d average EECs and the appropriate toxicity reference values (Table 7). Table 22 summarizes

the acute and chronic RQs for freshwater and estuarine/marine invertebrates in the water column. 

Acute RQs for freshwater invertebrates ranged from 0.001 (ground application to almonds and 

pistachios) to 0.02 (aerial application to ornamentals), both of which are below all the acute 

LOCs. Chronic RQs to freshwater fish ranged from 0.02 (ground application to almonds and 

pistachios) to 0.25 (aerial applications to ornamentals), both of which are below the chronic LOC 

of 1.

Acute RQs for estuarine/marine invertebrates ranged from 0.01 (ground application to almonds 

and pistachios) to 0.11 (aerial application to ornamentals, NJ scenario), the highest of which is 

above the acute restricted use LOC. Aerial and ground uses to ginseng for the MN sugarbeet 

scenario exceeded the acute endangered species LOC as well as for the other two scenarios for 

ornamentals (MI and TN nursery scenarios). Chronic RQs for estuarine/marine invertebrates 

could not be estimated with certainty as they were derived from a non-definitive endpoint. The 

estimates however represent a maximum upper bound estimate of risk, all of which were below 

the chronic LOC of 1. The uncertainty in these upper and lower bound RQs is discussed further 

in the Risk Description, Section 7.2.1.

Table 22. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to 

freshwater and estuarine/marine invertebrates. 

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EEC

Peak

(μg 

a.i./L)

EEC

21-Day

(μg 

a.i./L)

LC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Acute RQ 

(Peak 

EEC/LC50)

Chronic

RQ

(21-day 

EEC/NOAEC)

Almonds

(CA 

Almond)

Freshwater 

invertebrates

Aerial 10.21 9.8 5500 340 0.002 0.03

Ground 7.41 7.34 0.001 0.02

Estuarine/marine 

invertebrates

Aerial 10.21 9.8 780 >98 0.01 <0.10

Ground 7.41 7.34 0.01 <0.07

Pistachios

(CA 

Almond)

Freshwater 

invertebrates

Aerial 10.21 9.8 5500 340 0.002 0.03

Ground 7.41 7.34 0.001 0.02

Estuarine/marine 

invertebrates

Aerial 10.21 9.8 780 >98 0.01 <0.10

Ground 7.41 7.34 0.01 <0.07

Lettuce

(CA 

Lettuce)

Freshwater 

invertebrates

Aerial 30.51 29.49 5500 340 0.006 0.09

Ground 27.6 26.6 0.005 0.08

Estuarine/marine 

invertebrates

Aerial 30.51 29.49

780 >98

0.04 <0.30

Ground 27.6 26.6 0.04 <0.27
64

Table 22. Acute and chronic RQs for evaluating risk of fenpyrazamine exposure to 

freshwater and estuarine/marine invertebrates. 

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EEC

Peak

(μg 

a.i./L)

EEC

21-Day

(μg 

a.i./L)

LC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Acute RQ 

(Peak 

EEC/LC50)

Chronic

RQ

(21-day 

EEC/NOAEC)

Grapes

(NY 

Grapes)

Freshwater 

invertebrates

Aerial 25.61 24.96 5500 340 0.005 0.07

Ground 21.73 21.2 0.004 0.06

Estuarine/marine 

invertebrates

Aerial 25.61 24.96 780 >98 0.03 <0.25

Ground 21.73 21.2 0.03 <0.22

Bushberries 

(NY 

Grapes) 

Freshwater 

invertebrates

Aerial 25.61 24.96 5500 340 0.005 0.07

Ground 21.73 21.2 0.004 0.06

Estuarine/marine 

invertebrates

Aerial 25.61 24.96 780 >98 0.03 <0.25

Ground 21.73 21.2 0.03 <0.22

Caneberries 

(NY 

Grapes)

Freshwater 

invertebrates

Aerial 25.61 24.96 5500 340 0.005 0.07

Ground 21.73 21.2 0.004 0.06

Estuarine/marine 

invertebrates

Aerial 25.61 24.96 780 >98 0.03 <0.25

Ground 21.73 21.2 0.03 <0.22

Strawberries

(FL 

Strawberry)

Freshwater 

invertebrates

Aerial 30.92 29.59 5500 340 0.006 0.09

Ground 27.42 26.23 0.005 0.08

Estuarine/marine 

invertebrates

Aerial 30.92 29.59 780 >98 0.04 <0.30

Ground 27.42 26.23 0.04 <0.27

Ginseng 

(MN 

Sugarbeet)

Freshwater 

invertebrates

Aerial 42.65 41.03 5500 340 0.008 0.12

Ground 37.5 36.14 0.007 0.11

Estuarine/marine 

invertebrates

Aerial 42.65 41.03 780 >98 0.06 <0.42

Ground 37.5 36.14 0.05 <0.37

Ginseng 

(MI 

Asparagus)

Freshwater 

invertebrates

Aerial 14.3 13.85 5500 340 0.003 0.04

Ground 9.98 9.89 0.002 0.03

Estuarine/marine 

invertebrates

Aerial 14.3 13.85 780 >98 0.02 <0.14

Ground 9.98 9.89 0.01 <0.10

Ornamentals

(MI 

Nursery)

Freshwater 

invertebrates

Aerial 61.92 60.8 5500 340 0.01 0.18

Ground 56.43 55.98 0.01 0.16

Estuarine/marine 

invertebrates

Aerial 61.92 60.8 780 >98 0.08 <0.62

Ground 56.43 55.98 0.07 <0.57

Ornamentals

(NJ 

Nursery)

Freshwater 

invertebrates

Aerial 86.6 83.92 5500 340 0.02 0.25

Ground 81.22 78.7 0.02 0.23

Estuarine/marine 

invertebrates

Aerial 86.6 83.92 780 >98 0.11 <0.86

Ground 81.22 78.7 0.10 <0.80

Ornamentals

(TN 

Nursery)

Freshwater 

invertebrates

Aerial 44.67 43.5 5500 340 0.008 0.13

Ground 38.41 37.3 0.007 0.11

Estuarine/marine 

invertebrates

Aerial 44.67 43.5 780 >98 0.06 <0.44

Ground 38.41 37.3 0.05 <0.38

Bolded values represent LOC exceedances.

LOCs are: acute endangered species = 0.05; acute restricted use = 0.1; acute high risk = 0.5; chronic risk = 1

b. Sediment Exposure: Chronic Risk to Benthic Invertebrates

Comparisons of EECs and sediment toxicity endpoints are provided below to supplement risk 

estimation to water column organisms. The evaluation of toxic risk to the benthic organisms was 

approached by assuming equilibrium partitioning fenpyrazamine between the sediment and the 

pore water (the water found between particulates in the sediment). Risk to benthic organisms 

was assessed using two approaches: (1) EECs for sediment were model-generated 

(PRZM/EXAMS) and compared to the toxicity value as reported for sediment exposure 
65

(NOAEC) in the sediment toxicity tests (normalized to organic carbon) and (2) EECs for pore 

water were model-generated (PRZM/EXAMS) and compared to the toxicity value as reported for 

pore water (NOAEC) in the sediment toxicity tests. 

As discussed in Section 4.4.1 of this assessment, there were three chronic sediment toxicity

studies submitted in support of fenpyrazamine. The duration of these three toxicity studies range 

from 28 to 42 days. For estimating sediment and pore water RQs for benthic invertebrates, the 

PRZM/EXAMS 21-day averages for sediment and pore water EECs will be used along with the 

respective sediment and pore water NOAEC endpoints for the sediment toxicity studies. The 21-

day average EECs for sediment and pore water resulting from the proposed uses of 

fenpyrazamine, as well as the chronic NOAEC values from the sediment toxicity studies and 

their resultant RQs can be found below in Table 23 for freshwater benthic invertebrates and

Table 24 for estuarine/marine benthic invertebrates.

For freshwater and estuarine/marine benthic invertebrates, chronic RQs were estimated from 

non-definitive toxicity endpoints and therefore the actual RQs are not known with certainty. 

Preliminary analysis shows the chronic LOC of 1 is exceeded with certainty with freshwater 

invertebrates for the ginseng (MN sugarbeet) use and all scenarios conducted for the ornamental 

use. These exceedances of the chronic LOC of 1 are true for both sediment-based RQ and porewater based RQs. For estuarine/marine benthic invertebrates the LOC of 1 is not exceeded with 

certainty for all proposed uses of fenpyrazamine but where exactly the RQ falls is an uncertainty. 

The uncertainty in these upper and lower bound RQs are discussed further in the Risk 

Description, Section 7.2.1.

Table 23. Chronic RQs for risk of fenpyrazamine exposure to freshwater benthic 

invertebrates1,2. 

Crop

(Specific 

scenario)

Application 

Method

Sediment 

EEC

(μg a.i./ 

kg

sediment)

Pore 

Water 

EEC

(μg a.i./L 

pore 

water)

NOAEC 

(μg 

a.i./kg 

sediment)

NOAEC (μg 

a.i./L pore 

water)

Sediment

RQ

Pore water

RQ

Almonds, 

Pistachios

Ground 30 5.26

<101 <20

>0.30 >0.26

Aerial 20 3.93 >0.20 >0.20

Lettuce

Ground 80 15.25 >0.79 >0.76

Aerial 80 13.89 >0.79 >0.69

Grapes, 

Bushberries, 

Caneberries

Ground 90 15.75 >0.89 >0.79

Aerial 70 13.56 >0.69 >0.68

Strawberries

Ground 70 13.19 >0.69 >0.66

Aerial 60 11.53 >0.59 >0.58

Ginseng

(MN 

Sugarbeet)

Ground 130 23.07 >1.29 >1.15

Aerial

110 20.6 >1.09 >1.03

Ginseng (MI 

asparagus)

Ground 60 10.57 >0.59 >0.53

Aerial

40 7.61 >0.40

>0.38
66

Table 23. Chronic RQs for risk of fenpyrazamine exposure to freshwater benthic 

invertebrates1,2. 

Crop

(Specific 

scenario)

Application 

Method

Sediment 

EEC

(μg a.i./ 

kg

sediment)

Pore 

Water 

EEC

(μg a.i./L 

pore 

water)

NOAEC 

(μg 

a.i./kg 

sediment)

NOAEC (μg 

a.i./L pore 

water)

Sediment

RQ

Pore water

RQ

Ornamental

(MI Nursery)

Ground 210 38.2 >2.08 >1.91

Aerial 190 34.08 >1.88 >1.70

Ornamental 

(NJ Nursery)

Ground 250 46.79 >2.48 >2.34

Aerial 240 43.92 >2.38 >2.20

Ornamental

(TN Nursery)

Ground 130 23.24 >1.29 >1.16

Aerial 110 19.94 >1.09 >1.00

1Using 101 μg a.i/kg sediment and 20 μg a.i/L as upper bound estimates of sediment and pore water toxicity, respectively.

2

PRZM/EXAMS 21-day average EECs will be used for estimation of RQs.

Bolded values represent RQs exceeding the chronic aquatic organism RQ of 1.

Table 24. Chronic RQs for risk of fenpyrazamine exposure to estuarine/marine benthic 

invertebrates1,2,3. 

Crop

(Specific 

scenario)

Application 

Method

Sediment 

EEC

(μg a.i./ 

kg

sediment)

Pore 

Water 

EEC

(μg a.i./L 

pore 

water)

NOAEC

, 

(μg 

a.i./kg 

sediment)

NOAEC (μg 

a.i./L pore 

water)

Sediment

RQ

Pore water

RQ

Almonds, 

Pistachios

Ground 30 5.26

<3000 <250

>0.01 >0.02

Aerial 20 3.93 >0.01 >0.02

Lettuce

Ground 80 15.25 >0.03 >0.06

Aerial 80 13.89 >0.03 >0.06

Grapes, 

Bushberries, 

Caneberries

Ground 90 15.75 >0.03 >0.06

Aerial 70 13.56 >0.02 >0.05

Strawberries

Ground 70 13.19 >0.02 >0.05

Aerial 60 11.53 >0.02 >0.05

Ginseng

(MN 

Sugarbeet)

Ground 130 23.07 >0.04 >0.09

Aerial

110 20.6 >0.04 >0.08

Ginseng

Ground 60 10.57 >0.02 >0.04

Aerial 40 7.61 >0.01 >0.03

Ornamental

(MI Nursery)

Ground 210 38.2 >0.07 >0.15

Aerial 190 34.08 >0.06 >0.14

Ornamental 

(NJ Nursery)

Ground 250 46.79 >0.08 >0.19

Aerial 240 43.92 >0.08 >0.18

Ornamental

(TN Nursery)

Ground 130 23.24 >0.04 >0.09

Aerial 110 19.94 >0.04 >0.08
67

Table 24. Chronic RQs for risk of fenpyrazamine exposure to estuarine/marine benthic 

invertebrates1,2,3. 

Crop

(Specific 

scenario)

Application 

Method

Sediment 

EEC

(μg a.i./ 

kg

sediment)

Pore 

Water 

EEC

(μg a.i./L 

pore 

water)

NOAEC

, 

(μg 

a.i./kg 

sediment)

NOAEC (μg 

a.i./L pore 

water)

Sediment

RQ

Pore water

RQ

1Using 3 mg a.i/kg sediment and 0.25 mg a.i/L as upper bound estimates of sediment and pore water toxicity, respectively.

2

PRZM/EXAMS 21-day average EECs will be used for estimation of RQs.

3Chronic aquatic LOC is 1.

c. Aquatic Plants 

RQs were estimated for listed and non-listed vascular and non-vascular (algae) plants. The most 

sensitive EC50 values for vascular and non-vascular plants were used with the peak EEC for all 

proposed uses of fenpyrazamine to yield non-listed aquatic plant RQs. Similarly, the most 

sensitive NOAEC values for vascular and non-vascular plants were with the peak EECs to yield 

listed aquatic plant RQs. The LOC for both listed and non-listed aquatic plants is 1. Table 25

below summarizes the peak EECs for each use, as well as the most sensitive EC50 and NOAEC 

values from available toxicity studies. For the proposed uses of fenpyrazamine, there were no 

non-listed vascular plant LOC exceedances (RQs ranged from 0.001 – 0.08) and for non-vascular 

plants, all but two uses (almonds and pistachios) exceeded the non-listed LOC (RQs ranged from 

0.67 – 7.87). For listed aquatic plants, there was a similar trend with no vascular plant LOC 

exceedances (RQs ranged from 0.01 – 0.14) and non-vascular aquatic plant exceedances for all 

proposed uses (RQs ranged from 1.51 – 17.67)

Table 25. RQs for evaluating toxic risk of fenpyrazamine exposure to vascular and nonvascular aquatic plants.

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EECc

Peak

(μg 

a.i./L)

EC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Non-listed 

aquatic 

plants RQ 

(Peak 

EEC/EC50)

Listed aquatic 

plants RQ

(Peak

EEC/NOAEC

or EC05)

Almonds

(CA Almond)

Nonvascular 

aquatic plants

Aerial 10.21 11 4.9 0.93 2.08

Ground 7.41 0.67 1.51

Vascular aquatic 

plants

Aerial 10.21 1100 600 0.01 0.02

Ground 7.41 0.01 0.01

Pistachios

(CA Almond)

Nonvascular 

aquatic plants

Aerial 10.21 11 4.9 0.93 2.08

Ground 7.41 0.67 1.51

Vascular aquatic 

plants

Aerial 10.21 1100 600 0.01 0.02

Ground 7.41 0.01 0.01

Lettuce

(CA Lettuce)

Nonvascular 

aquatic plants

Aerial 30.51 11 4.9 2.77 6.23

Ground 27.6 2.51 5.63

Vascular aquatic 

plants

Aerial 30.51

1100 600

0.03 0.05

Ground 27.6 0.03 0.05
68

Table 25. RQs for evaluating toxic risk of fenpyrazamine exposure to vascular and nonvascular aquatic plants.

Crop

(PRZM 

Scenario)

Taxa Application 

Method

EECc

Peak

(μg 

a.i./L)

EC50

(μg 

a.i./L)

NOAEC

(μg 

a.i./L)

Non-listed 

aquatic 

plants RQ 

(Peak 

EEC/EC50)

Listed aquatic 

plants RQ

(Peak

EEC/NOAEC

or EC05)

Grapes

(NY Grapes)

Nonvascular 

aquatic plants

Aerial 25.61

11 4.9

2.33 5.23

Ground 21.73 1.98

4.43

Vascular aquatic 

plants

Aerial 25.61 1100 600 0.02 0.04

Ground 21.73 0.02 0.04

Bushberries 

(NY Grapes) 

Nonvascular 

aquatic plants

Aerial 25.61 11 4.9 2.33 5.23

Ground 21.73 1.98 4.43

Vascular aquatic 

plants

Aerial 25.61 1100 600 0.02 0.04

Ground 21.73 0.02 0.04

Caneberries 

(NY Grapes)

Nonvascular 

aquatic plants

Aerial 25.61 11 4.9 2.33 5.23

Ground 21.73 1.98 4.43

Vascular aquatic 

plants

Aerial 25.61 1100 600 0.02 0.04

Ground 21.73 0.02 0.04

Strawberries

(FL 

Strawberry)

Nonvascular 

aquatic plants

Aerial 30.92

11 4.9

2.81 6.31

Ground

27.42 2.49 5.60

Vascular aquatic 

plants

Aerial 30.92 1100 600 0.03 0.05

Ground 27.42 0.02 0.05

Ginseng 

(MN 

Sugarbeet)

Nonvascular 

aquatic plants

Aerial 14.3 11 4.9 3.88 8.70

Ground 9.98 3.41 7.65

Vascular aquatic 

plants

Aerial 14.3 1100 600 0.04 0.07

Ground 9.98 0.03 0.06

Ginseng 

(MI 

Asparagus)

Nonvascular 

aquatic plants

Aerial 61.92 11 4.9 1.30 2.92

Ground 56.43 0.91 2.04

Vascular aquatic 

plants

Aerial 61.92 1100 600 0.01 0.02

Ground 56.43 0.01 0.02

Ornamentals

(MI Nursery)

Nonvascular 

aquatic plants

Aerial 86.6 11 4.9 5.63 12.64

Ground 81.22 5.13 11.52

Vascular aquatic 

plants

Aerial 86.6 1100 600 0.06 0.10

Ground 81.22 0.05 0.09

Ornamentals

(NJ Nursery)

Nonvascular 

aquatic plants

Aerial 44.67 11 4.9 7.87 17.67

Ground 38.41 7.38 16.58

Vascular aquatic 

plants

Aerial 44.67 1100 600 0.08 0.14

Ground 38.41 0.07 0.14

Ornamentals

(TN Nursery)

Nonvascular 

aquatic plants

Aerial 14.3 11 4.9 4.06 9.12

Ground 9.98 3.49 7.84

Vascular aquatic 

plants

Aerial 61.92 1100 600 0.04 0.07

Ground 56.43 0.03 0.06

Bolded represent LOC exceedances.

LOC for non-listed and listed aquatic plants (vascular and non-vascular) is 1.
69

7.1.2 Non-target Terrestrial Animals

a. Acute and Chronic Risk to Birds 

T-REX provides acute dose based RQs for three size classes of birds as well as acute and chronic 

dietary based RQs resulting from ingestion of six different food items exposed to fenpyrazamine. 

Table 26 below summarizes the acute dose-based RQs to birds for all proposed uses of 

fenpyrazamine. The acute endangered species LOC was exceeded for small birds eating short 

grass for all proposed uses and for medium sized birds eating short grass for all uses except 

almonds and pistachios. The acute restricted use LOC was exceeded for small birds eating short 

grass for all uses except almonds and pistachios. Exceedances of the endangered species and 

restricted use LOC from other food items were only for small birds except for the ornamental use 

with medium sized birds eating short grass, tall grass, and broadleaf plants. There was one acute 

high risk (non-listed species) LOC exceedance which was for small birds eating short grass due 

to exposure from the ornamental use. 

Table 26. Dose-based RQs for birds due to exposure to proposed uses of fenpyrazamine.

Use

Size 

Class 

(grams)

Adjusted 

LD50

RQs1

Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods Arthropods Seeds

Almonds, 

pistachios

20 1440.86 <0.18 <0.08 <0.10 <0.01 <0.07 <0.003

100 1834.29 <0.08 <0.04 <0.05 <0.01 <0.03 <0.001

1000 2591.00 <0.03 <0.01 <0.01 <0.002 <0.01 <0.0004

Lettuce

20 1440.86 <0.24 <0.11 <0.14 <0.02 <0.10 <0.003

100 1834.29 <0.11 <0.05 <0.06 <0.01 <0.04 <0.002

1000 2591.00 <0.03 <0.02 <0.02 <0.002 <0.01 <0.0005

Grapes, 

bushberries, 

caneberries

20 1440.86 <0.24 <0.11 <0.14 <0.02 <0.10 <0.003

100 1834.29 <0.11 <0.05 <0.06 <0.01 <0.04 <0.002

1000 2591.00 <0.03 <0.02 <0.02 <0.002 <0.01 <0.0005

Strawberries

20 1440.86 <0.31 <0.14 <0.17 <0.02 <0.12 <0.004

100 1834.29 <0.14 <0.06 <0.08 <0.01 <0.05 <0.002

1000 2591.00 <0.04 <0.02 <0.02 <0.003 <0.02 <0.01

Ginseng

20 1440.86 <0.31 <0.14 <0.17 <0.02 <0.12 <0.004

100 1834.29 <0.14 <0.06 <0.08 <0.01 <0.05 <0.002

1000 2591.00 <0.04 <0.02 <0.02 <0.003 <0.02 <0.01

Ornamentals

20 1440.86 <0.53 <0.24 <0.30 <0.03 <0.21 <0.01

100 1834.29 <0.24 <0.11 <0.13 <0.01 <0.09 <0.003

1000 2591.00 <0.08 <0.03 <0.04 <0.005 <0.03 <0.001

Bolded values represent LOC exceedances

1LOCs are: acute endangered species = 0.1, acute restricted use = 0.2; acute high risk = 0.5

Table 27 summarizes the acute and chronic dietary based RQs for birds resulting from ingestion 

of five different food items exposed to fenpyrazamine. There were no acute LOC exceedances 

for any of the proposed uses on fenpyrazamine. The chronic LOC of 1 was exceeded for birds 

eating short grass in all proposed uses except for the use on almonds and pistachios, and for birds 

eating tall grass and broadleaf plants for the ornamental use only. For both acute oral toxicity

studies to birds, there were non-definitive values (>2000 mg a.i/kg-bw for both the northern 

bobwhite quail and canary). 
70

Acute dose-based RQs for birds ranged from 0.0004 – 0.53 thus indicating a potential for acute 

risks to various size classes of birds species ingesting various food items for all proposed uses. 

Acute dietary-based RQs for birds ranged from 0.2 – 0.15 indicating a potential for acute risks to 

endangered avian species eating short grass exposed to the ornamental use of fenpyrazamine. 

Chronic-dietary based RQs ranged from 0.06 – 2.72 indicating a potential for chronic risks to 

mammals ingesting various food items for all proposed uses except almonds and pistachios. 

For both dietary toxicity studies, there were also non-definitive values (>4430 ppm) that were 

used to estimate RQs. Therefore, while the estimates are shown in Table 26 and Table 27, the

precise values of these acute RQs are uncertain. The RQs summarized in Table 26 and Table 

27 lists the upper bound of the acute RQ, that is, the value of risk at most for a given use. This 

is still useful for risk assessment despite the uncertainties associated with non-definitive toxicity

endpoints.

Table 27. Dietary-based RQs for birds due to exposure to proposed uses of fenpyrazamine.

Use

RQs1

Exposure Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods/seeds Arthropods

Almonds, pistachios Acute <0.05 <0.02 <0.03 <0.003 <0.02

Chronic 0.94 0.43 0.53 0.06 0.37

Lettuce Acute <0.07 <0.03 <0.04 <0.004 <0.03

Chronic 1.25 0.57 0.70 0.08 0.49

Grapes, bushberries, 

caneberries

Acute <0.07 <0.03 <0.04 <0.004 <0.03

Chronic 1.25 0.57 0.70 0.08 0.49

Strawberries Acute <0.09 <0.04 <0.05 <0.01 <0.03

Chronic 1.56 0.71 0.88 0.10 0.61

Ginseng Acute <0.09 <0.04 <0.05 <0.01 <0.03

Chronic 1.56 0.71 0.88 0.10 0.61

Ornamentals Acute <0.15 <0.07 <0.09 <0.01 <0.06

Chronic 2.72 1.25 1.53 0.17 1.07

Bolded values represent LOC exceedances

1LOCs are: acute endangered species = 0.1, acute restricted use = 0.2; acute high risk = 0.5; chronic LOC = 1

b. Acute and Chronic Risk to Mammals 

T-REX provides acute and chronic dose- based RQs for three size classes of mammals as well as 

chronic dietary based RQs resulting from ingestion of six different food items exposed to 

fenpyrazamine. Table 28 below summarizes the acute dose-based RQs to mammals for all 

proposed use of fenpyrazamine. The acute endangered species LOC was exceeded for mammals 

eating short grass for only the proposed use on ornamentals. There are no other acute dose-based 

LOC exceedances for mammals. Table 29 summarizes the chronic dose-based RQs to mammals 

for all proposed uses. The chronic LOC of 1 was exceeded for all size classes of mammals 

eating various food items for the ornamental use only. The chronic LOC was exceeded by small 

and medium sized mammals eating tall grass, broadleaf plants, and arthropods was exceeded for 

all uses except almonds and pistachios (no exceedances) and lettuce, grapes, bushberries, and 

caneberries (exceedances only for small mammals). Table 30 summarizes the chronic dietarybased RQ for all proposed uses of fenpyrazamine. There are no LOC exceedances for these RQs.
71

Acute dose-based RQs for mammals ranged from 0.0004 – 0.15 thus indicating a potential for 

acute risks to endangered mammalian species ingesting short grass for the ornamental use only. 

Chronic dose-based RQs ranged from 0.1 – 5.86 indicating a potential for chronic risks to 

mammals for all various size class ingesting various food items for all proposed uses. There are

no chronic dietary based LOC exceedances for mammals.

For the acute oral toxicity study to mammals, there was a non-definitive endpoint (>2000 mg 

a.i/kg-bw) determined. Therefore, while the estimates are shown in Table 28, the precise values 

of these acute RQs are uncertain. The RQs summarized in Table 28 lists the upper bound of the 

acute RQ, that is, the value of risk at most for a given use. This is still useful for risk assessment 

despite the uncertainties associated with non-definitive toxicity endpoints.

Table 28. Acute dose-based RQs for mammals due to exposure to proposed uses of 

fenpyrazamine.

Use

Size 

Class 

(grams)

Adjusted 

LD50

RQs1

Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods Arthropods Seeds

Almonds, 

pistachios

15 4395.66 <0.05 <0.02 <0.03 <0.003 <0.02 <0.001

35 3556.56 <0.04 <0.02 <0.02 <0.003 <0.02 <0.001

1000 1538.32 <0.02 <0.01 <0.01 <0.001 <0.01 <0.0003

Lettuce

15 4395.66 <0.07 <0.03 <0.04 <0.004 <0.03 <0.001

35 3556.56 <0.06 <0.03 <0.03 <0.004 <0.02 <0.001

1000 1538.32 <0.03 <0.01 <0.02 <0.002 <0.01 <0.0004

Grapes, 

bushberries, 

caneberries

15 4395.66 <0.07 <0.03 <0.04 <0.004 <0.03 <0.001

35 3556.56 <0.06 <0.03 <0.03 <0.004 <0.02 <0.001

1000 1538.32 <0.03 <0.01 <0.02 <0.002 <0.01 <0.0004

Strawberries

15 4395.66 <0.08 <0.04 <0.05 <0.01 <0.03 <0.001

35 3556.56 <0.07 <0.03 <0.04 <0.004 <0.03 <0.001

1000 1538.32 <0.04 <0.02 <0.02 <0.002 <0.02 <0.001

Ginseng

15 4395.66 <0.08 <0.04 <0.05 <0.01 <0.03 <0.001

35 3556.56 <0.07 <0.03 <0.04 <0.004 <0.03 <0.001

1000 1538.32 <0.04 <0.02 <0.02 <0.002 <0.02 <0.001

Ornamentals

15 4395.66 <0.15 <0.07 <0.08 <0.01 <0.06 <0.002

35 3556.56 <0.13 <0.06 <0.07 <0.01 <0.05 <0.002

1000 1538.32 <0.07 <0.03 <0.04 <0.004 <0.03 <0.001

Bolded values represent LOC exceedances

1LOCs are: acute endangered species = 0.1, acute restricted use = 0.2; acute high risk = 0.5; chronic LOC = 1

Table 29. Chronic dose-based RQs for mammals from exposure to proposed uses of 

fenpyrazamine.

Use

Size 

Class 

(grams)

Adjusted 

LD50

RQs1

Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods Arthropods Seeds

Almonds, 

pistachios

15 4395.66 1.27 0.58 0.71 0.08 0.50 0.02

35 3556.56 1.08 0.50 0.61 0.07 0.42 0.02

1000 1538.32 0.58 0.27 0.33 0.04 0.23 0.01

Lettuce

15 4395.66 1.68 0.77 0.94 0.10 0.66 0.02

35 3556.56 1.43 0.66 0.81 0.09 0.56 0.02

1000 1538.32 0.77 0.35 0.43 0.05 0.30 0.01

Grapes, 15 4395.66 1.68 0.77 0.94 0.10 0.66 0.02
72

Table 29. Chronic dose-based RQs for mammals from exposure to proposed uses of 

fenpyrazamine.

Use

Size 

Class 

(grams)

Adjusted 

LD50

RQs1

Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods Arthropods Seeds

bushberries, 

caneberries

35 3556.56 1.43 0.66 0.81 0.09 0.56 0.02

1000 1538.32 0.77 0.35 0.43 0.05 0.30 0.01

Strawberries

15 4395.66 2.10 0.96 1.18 0.13 0.82 0.03

35 3556.56 1.79 0.82 1.01 0.11 0.70 0.02

1000 1538.32 0.96 0.44 0.54 0.06 0.38 0.01

Ginseng

15 4395.66 2.10 0.96 1.18 0.13 0.82 0.03

35 3556.56 1.79 0.82 1.01 0.11 0.70 0.02

1000 1538.32 0.96 0.44 0.54 0.06 0.38 0.01

Ornamentals

15 4395.66 3.66 1.68 2.06 1.44 0.05 0.05

35 3556.56 3.13 1.43 1.76 0.20 1.23 0.04

1000 1538.32 1.68 0.77 0.94 0.10 0.66 0.02

Bolded values represent LOC exceedances

1LOCs are: acute endangered species = 0.1, acute restricted use = 0.2; acute high risk = 0.5; chronic LOC = 1

Table 30. Chronic dietary-based RQs for mammals due to exposure to proposed uses of 

fenpyrazamine.

Use

RQs1

Exposure Short 

grass

Tall 

grass

Broadleaf 

plants Fruits/pods/seeds Arthropods

Almonds, pistachios Chronic 0.23 0.11 0.13 0.01 0.09

Lettuce Chronic 0.31 0.14 0.17 0.02 0.12

Grapes, bushberries, 

caneberries Chronic 0.31 0.14 0.17 0.02 0.12

Strawberries Chronic 0.39 0.18 0.22 0.02 0.15

Ginseng Chronic 0.39 0.18 0.22 0.02 0.15

Ornamentals Chronic 0.67 0.31 0.38 0.04 0.26

Bolded values represent LOC exceedances

1LOCs are: acute endangered species = 0.1, acute restricted use = 0.2; acute high risk = 0.5; chronic LOC = 1

c. Non-target Beneficial Insects

The Agency does not currently conduct quantitative risk assessments for non-target beneficial 

insects (e.g., honeybee). Rather, the potential exposure of honeybees to pesticides is assessed 

qualitatively based on laboratory data and if available, field data. Furthermore, when used alone,

fenpyrazamine, consistent with other carboxamide pyrazole fungicides, does not possess a mode 

of action consistent with systemic fungicides

11

. Therefore, potential exposure via transport 

within the plant to pollen and nectar is reduced. It is also noted that fenpyrazamine is classified 

as practically non-toxic to honeybee (acute contact LD50 >100 ug a.i/bee) and was shown to be 

non-toxic at a dose of 100 μg a.i/bee in an acute oral exposure study. Therefore, while the 

 

11 Uptake of fenpyrazamine residues was observed in wheat, lettuce, and carrots in an accumulation in confined 

rotational crop study conducted under a greenhouse (MRID No. 48400043). However, under field conditions, 

fenpyrazamine, S-2188-DC, or S-2188-OH residues were not detected in rotational field crops in Europe (Citation: 

Austria, 2011a. Draft assessment report on the active substance fenpyrazamine prepared by the rapporteur Member 

State Austria in the framework of Council Directive 91/414/EEC, January 2011).
73

potential exists via exposure pathways such as spray drift to impact insects like honeybees, the 

limited available data show that fenpyrazamine is not shown to be toxic. 

d. Risks to Terrestrial Plants

Seedling emergence and vegetative vigor studies are available for fenpyrazamine. The estimates 

of exposure generated by TerrPlant and described in Section 6.2.2 were compared to estimates of 

toxicity to estimate RQ for listed and non listed plants in dry and semi aquatic areas. For 

almonds and pistachios, the chronic LOC of 1 was exceeded for listed dicot species in semi 

aquatic areas. There are no other LOC exceedances for this use. For lettuce, grapes, 

bushberries, caneberries, strawberries, and ginseng, the chronic LOC of 1 was exceeded for 

listed dicot species in semi aquatic areas with no other LOC exceedances. For the use on 

ornamentals, listed monocot species in semi aquatic areas and listed dicot areas in dry, semi 

aquatic, and areas resulting from spray drift all exceeded the chronic LOC. Therefore, the 

potential for risk is indicated to these groups of terrestrial plants from the uses exceeding the 

LOC of 1. 

It is important to note that the RQs summarized in Table 32 did not have EC25 endpoints input 

into the TerrPlant model for vegetative vigor on account of a lack of toxicity for these studies 

precluding that endpoint to be estimated. Furthermore, the NOAEC for seedling emergence for 

dicot species was a non-definitive endpoint (<0.035 lbs a.i/A). Additionally, the EC25 values for 

seedling emergence (monocot and dicot) were non definitive (>1.54 ad >0.53 for monocots and 

dicots, respectively). Therefore while the RQs are summarized in Table 31, the RQs are not 

determined to be precise, and there exists uncertainty with these endpoints that arises from the 

use of non-definitive RQs. This is detailed further as it pertains to terrestrial plants in the Risk 

Description, Section 7.2.3. The complete input and output files from TerrPlant can be found in 

Appendix D.

Table 31. RQs for terrestrial plants resulting from the propose uses of fenpyrazamine.

Crop Use1

Plant Type Listed 

Status

Dry

SemiaquaticSpray 

Drift

Almonds, pistachios

Monocot Non-listed <0.1 <0.01 <0.1

Monocot Listed 0.17 0.62 <0.1

Dicot Non-listed <0.1 0.17 <0.1

Dicot Listed 0.74 2.64 0.53

Lettuce, Grapes, Caneberries, Bushberries, 

Strawberries, Ginseng

Monocot Non-listed <0.01 0.20 <0.01

Monocot Listed 0.23 0.82 <0.1

Dicot Non-listed <0.01 0.23 <0.1

Dicot Listed 0.98 3.50

0.70
74

Table 31. RQs for terrestrial plants resulting from the propose uses of fenpyrazamine.

Crop Use1

Plant Type Listed 

Status

Dry

SemiaquaticSpray 

Drift

Ornamentals

Monocot Non-listed 0.12 0.45 <0.1

Monocot Listed 0.50 1.78 <0.1

Dicot Non-listed 0.14 0.50 0.1

Dicot Listed 2.14 7.64 1.53

1

Single application rates for TerrPlant modeling are 0.37 lbs a.i/A for almonds and pistachios, 0.49 lbs a.i/A for 

lettuce, grapes, caneberries, bushberries, strawberries, and ginseng, and 1.07 lbs a.i/A for ornamentals

Bolded values represent LOC exceedances of the listed and non-listed terrestrial plant LOC of 1

7.2 Risk Description

In risk description, the results from the risk estimation are interpreted and synthesized into 

overall risk conclusions. When available, other lines of evidence are considered for 

characterizing ecological risk (e.g., monitoring data, ecological incident reports, refined exposure 

and effects modeling, data for structurally similar pesticides, etc.). In the case of fenpyrazamine, 

no information is available on monitored concentrations in the environment or ecological 

incident reports because it is a new pesticide. The risk description also contains a discussion of 

relevant sources of uncertainty in the risk assessment and sensitivity of the risk assessment 

findings to important methodological assumptions. Those uncertainties that are specific to 

certain taxonomic groups are discussed in the following sections. Those uncertainties that are 

generic to this assessment (i.e., extending across taxonomic groups) are described in Section 

7.2.6.d.

7.2.1 Risks to Aquatic Animals 

a. Potential for Acutely Toxic Exposures 

 Fish 

The previous risk estimation indicates a low potential for acutely toxic exposures to freshwater 

and estuarine/marine fish animals from the proposed uses of fenpyrazamine. The highest 

estimated acute RQs for freshwater fish are 3 times below the listed species LOC of 0.05 

and the lowest RQs are one order of magnitude lower. For acute risk to estuarine/marine fish, 

RQs were estimated from a non-definitive endpoint (>3900 μg a.i/L). As a result, the RQs that 

were estimated represent at most what the RQ would fall but the precise value of the RQ is 

uncertain. An LC50 of >3900 μg a.i./L would yield an RQ that be preceded with an “<” 

indicating that the estimated value would at most be the calculated RQ. Even with the 

uncertainty in these RQs calculated from non-definitive endpoints, they are still useful in risk 

assessment in terms of serving as a screen and in this case indicate that acute risk to 

estuarine/marine fish is at most approximately 2 times below the listed species LOC of 0.05. 
75

Acute toxicity data was available for two degradates of fenpyrazamine to freshwater fish (S2188-DC and S-2188-OH). These studies indicated that freshwater fish (using rainbow trout as a 

surrogate) was approximately 17 times more sensitive to parent fenpyrazamine than to these 

degradation products. While there were no degradate studies to estuarine/marine fish, degradates 

are expected to be of lower toxicity to this taxa similar to freshwater fish as indicated by a small 

difference in acute LC50 values for freshwater and estuarine/marine fish (5.2 mg a.i/L and >3.9 

mg a.i/L, respectively). Significant acute exposure to degradates in the water column is not 

expected. The most significant mechanism contributing to the potential input of degradation 

products into water bodies is anaerobic soil metabolism where degradation of fenpyrazamine of 

S-2188-OH and S-2188-DC occurs of levels up to 22.9 percent and 22 percent applied, 

respectively. There were no other cases where degradate residues contributed to greater than 10 

percent of the applied in soil. Once in the water column, fenpyrazamine is moderately persistent

to persistent in the water column, especially in acidic environments, with half-lives ranging from 

12.2 days – 280 days under aerobic and anaerobic conditions. 

 Aquatic Invertebrates

A low potential for acutely toxic exposure is also indicated for freshwater and estuarine/marine 

invertebrates. Freshwater invertebrate RQs at their highest are marginally close to the 

listed species LOC of 0.05 (NJ ornamental aerial use RQ of 0.02 Estuarine/marine 

invertebrates were shown to be more sensitive in ecotoxicological testing and as a result, the 

highest acute RQs for this taxa marginally exceed the acute restricted use LOC of 0.1 with 

aerial and ground application to ornamental (NJ nursery scenario) RQs of 0.11 and 0.1. . 

For two other scenarios of the ornamental use (MI and TN nursery), there was a marginal 

exceedance of the listed species LOC of 0.05 (RQs = 0.08 and 0.06 for the scenarios, 

respectively), as well as for the ginseng use (MN sugarbeet scenario, RQ = 0.06) Three 

acute toxicity studies with freshwater invertebrates (Daphnia magna) were submitted with three 

degradation products of fenpyrazamine (MCNI, S-2188-DC, and S-2188-OH). The results of 

these studies were similar to those of the results of the freshwater fish degradate studies. In the 

case of MCNI (the most toxic of the degradates) the LC50 was still approximately 10 times less 

toxic than parent fenpyrazamine. The degradates S-2188-DC and S-2188-OH were 

approximately 17 times less toxic than parent fenpyrazamine. Although, there were no degradate 

studies conducted on estuarine/marine invertebrates, the degradation products are expected to be 

less toxic than parent fenpyrazamine to this taxa as it was for freshwater invertebrates despite 

the fact that estuarine/marine invertebrates were shown to be more sensitive to parent chemical 

than freshwater invertebrates. Biodegradation and abiotic degradation of fenpyrazamine in the 

water column and availability of degradate products to runoff as described above for fish species

also suggest that exposure of degradate residues will not cause adverse impacts to aquatic 

invertebrates on an acute basis.

b. Potential for Chronically Toxic Exposures

 Fish 

Chronic toxicity studies are available for freshwater and estuarine/marine fish as early life stage 
76

studies. While the freshwater fish study (rainbow trout, MRID 48400003) reached a definitive 

NOAEC, the study with an estuarine/marine species (sheepshead minnow, MRID 48400004) 

yielded a non-definitive endpoint, <39 μg a.i/L. While estimation of RQs with this endpoint will 

not be entirely precise, it is still useful to quantify a lower bound estimate of risk since the RQs 

generated would be at least that value (i.e. a “>” value). Because of this, there is a high degree of 

uncertainty where the actual RQ falls. For example, an RQ of >0.18, while below the chronic 

LOC of 1 does have the potential to be in exceedance of the LOC and therefore an indicator for 

the potential of chronic effects. For the proposed uses on fenpyrazamine, estimated 

freshwater fish chronic RQs ranged from 0.02 – 0.22. The highest RQ is 5 times away from 

the chronic LOC of 1. For estuarine/marine fish, RQs were estimated using the NOAEC of 39 

μg a.i/L for bounding purposes. The resultant RQs would be preceded with a “>” sign to 

distinguish these RQs because the actual NOAEC is known to be below 39 μg a.i/L. 

Consequently, such unbounded RQs do not enable a conclusive determination of risk (or lack 

thereof) to be made. With the proposed uses of fenpyrazamine, the unbounded RQ for the 

ornamental use does exceed the chronic LOC of 1, yet how far above this threshold the actual 

RQ falls is an uncertainty. As mentioned previously, RQs derived from non-definitive endpoints 

are uncertain yet are still useful to quantify the potential effects in risk assessment. 

Despite the unbounded estimates of risk and the indication that the chronic LOC of 1 may be 

exceeded, there are two reasons why chronic risk to estuarine/marine fish may be presumed to be 

low. The first point relates to the fact the NOAEC for the chronic fish study was based on mean 

body length and the lowest treatment concentration of the study (39 μg a.i/L) resulted in a 4.3% 

reduction from the negative control. This response is considered relatively modest in nature 

from a biological perspective. Furthermore for this endpoint, the effects did not follow a dose 

response pattern with the next two higher concentrations (62 and 150 μg a.i/L) resulting in 

percent reductions from the control of 1.9 and 2.7% respectively. Additionally, the structure 

activity relationships tool, ECOSAR (v. 1.10) was employed to get a conservative estimation of 

chronic toxicity to estuarine/marine fish. ECOSAR estimates toxicity to various taxa by way of 

breaking down toxicity estimates by ECOSAR-specific classes (See Appendix G for further 

information on ECOSAR and its estimates of toxicity for the various degradation products of 

fenpyrazamine.) When the chemical structure is input into ECOSAR, the results of 4 ECOSAR 

classes are returned that includes aliphatic amines, hydrazines, amides, and thiocarbamates. For 

the aliphatic amines and hydrazine classes, only chronic results for fish are specified (as opposed 

to estuarine/marine fish) and for the amide and thiocarbamates classes there are specific chronic 

toxicity estimates for estuarine/marine fish estimated. The estimates of a chronic NOAEC for 

fish range from 0.2 to 19.6 mg/L, depending on the chemical class. For fenpyrazamine, the 

highest 1-in-10 year 60 day average EEC was for the NJ ornamental use and was 80.35 μg/L or 

0.08 mg/L. As the most sensitive estimate of chronic toxicity for fish as determined by

ECOSAR is one order of magnitude below the highest 60-day average EEC, the conservative 

estimates indicate risk below the chronic LOC. Taken with the unbounded estimated chronic 

RQs from the registrant submitted data, chronic risk for fish is indicated for the ornamental use 

only but it remains an uncertainty of where the actual estimate of the chronic RQs fall.

The second point relates to the likely conservative estimate of exposure for fenpyrazamine in the 

water column. The lower bound aspect of the risk quotient is mitigated due to the fact that 
77

hydrolysis is conservatively not included as a degradation pathway due to significant 

uncertainties in the hydrolysis study (MRID No. 48399923). The existing data on hydrolysis 

indicates that fenpyrazamine degrades to some extent, especially in alkaline environments. 

However, the exact rate at which it degrades under neutral conditions is unknown due to the lack 

of data available at environmentally relevant conditions. The exclusion of hydrolysis from water 

column under neutral conditions contributes to the overall steady EEC values of fenpyrazamine 

occurring over all averaging periods as shown in Table 12 and Table 13. In addition, the 

aquatic exposure modeling utilized the very conservative default assumption for input 

parameterization of anaerobic aquatic metabolism as only one sediment – water system was 

available. Therefore, the single anaerobic aquatic metabolism half life available for modeling 

was multiplied by three. Given the evidence for fenpyrazamine degradation due to hydrolysis 

especially over alkaline environments and that fenpyrazamine may be less persistent than 

modeled over neutral environments, it is possible that chronic EECs would be lower. 

Additionally, a new chronic ELS study that reaches a definitive NOAEC would address this 

uncertainty but refined EECs could negate the need for that data if it is indicated that exposure 

would be significantly reduced from present levels. 

 Aquatic Invertebrates (Water Column)

Chronic toxicity studies are available for both freshwater and estuarine/marine invertebrates. 

For freshwater invertebrates, chronic RQs ranged from 0.02 – 0.25. The highest RQ is 4

times lower than the chronic LOC of 1. For estuarine/marine invertebrates, RQs were 

estimated using the NOAEC of 98 μg a.i/L for bounding purposes. The resultant RQs would 

therefore be preceded by a “<” sign to distinguish these RQs because the actual NOAEC is 

known to be above 98 μg a.i/L. Consequently, such unbounded RQs do not enable a conclusive 

determination of risk (or lack thereof) to be made. In the case of chronic risk to estuarine/marine 

invertebrates however, there were no exceedances of the chronic LOC of 1 with the estimated 

unbounded RQs. As the actual bounded RQs are known to be below the estimated unbounded 

RQs, chronic risk to estuarine/marine invertebrates is expected to be low.

 Aquatic Invertebrates (Benthic)

Chronic toxicity studies are available for freshwater and estuarine/marine benthic invertebrates. 

Studies with the freshwater invertebrates Hyalella azteca and Chironomus riparius were 

conducted for 42-d and 28-d exposures, respectively. Additionally, a 28-day study with the 

estuarine/marine organism Leptocheirus plumulosus is available for risk estimation. The 21-day

1-in-10 year EEC for pore water is compared to the toxicity endpoint expressed in terms of pore 

water are compared to each other for pore water RQs and the same is done for 1-in-10-year 

sediment EECs and endpoints expressed in terms of sediment concentrations. Both the most 

sensitive endpoints from the freshwater and estuarine/marine benthic invertebrate studies 

resulted in NOAECs that were non-definitive. 

For the most sensitive freshwater benthic invertebrate study (C. riparius, MRID 48400007), the 

sediment and pore water expressed endpoints were <101 μg a.i/kg sediment and <20 μg a.i/L. 

The resultant RQs would be preceded with a “>” sign to distinguish these RQs because the actual 
78

NOAEC is known to be below 101 μg a.i/kg sediment and 20 μg a.i/L. Similarly, the most 

sensitive endpoints for the estuarine/marine benthic invertebrate were <3000 μg a.i/kg sediment 

and <250 μg a.i/L. The resultant RQs would be preceded with a “>” sign to distinguish these 

RQs because the actual NOAEC is known to be below 3000 μg a.i/kg sediment and 250 μg a.i/L. 

Consequently, such unbounded RQs do not enable a conclusive determination of risk (or lack 

thereof) to be made. It is noted however that the PRZM/EXAMS estimated pore water and 

sediment EECs do not significantly decline (rather in most cases, remain the same) from their 

peak values when extended out to 21-day and 60-day averages (Table 14, Table 15, Table 16, 

and Table 17). This likely is the artifact of using the conservative default assumption for input 

parametrization of anaerobic aquatic metabolism since only one study is available. With this 

uncertainty in mind, it is possible that sediment and pore water EECs would be lower than this 

assessment assumes but to what extent is also uncertain. 

Currently, the highest sediment 1-in-10 year 21-day average EECs is 250 μg a.i/kg sediment 

(Table 16), which is approximately 2.5 fold higher than the most sensitive freshwater benthic 

organism endpoint (<101 μg a.i/kg sediment) and almost 12 fold lower than the most sensitive 

estuarine/marine benthic invertebrate endpoint (<3000 μg a.i/kg sediment). Similarly, the highest 

pore water 1-in-10 year 21-d average EEC is 46.8 μg a.i/L (Table 14) which is approximately 2 

fold higher than the most sensitive freshwater benthic invertebrate endpoint (<20 μg a.i/L) and 

approximately 5 fold lower than the most sensitive estuarine/marine benthic invertebrate 

endpoint (<250 μg a.i/L). This illustrates the assumption that sediment and pore water EECs

which are calculated incorporating a robust sampling of water-sediment systems in an anaerobic 

environment may reduce the uncertainty of the non-definitive RQs by providing concentrations 

that are several fold or even orders of magnitude lower than the most sensitive sediment and pore 

water-expressed toxicity endpoints. Additionally, further sediment toxicity studies that reach 

definitive endpoints would also reduce the uncertainty of non-definitive RQs.

It should also be stated that as mentioned in Section 3, unextracted residues incorporated in soil 

or sediment layers are not included for benthic pore water or sediment EECs. The reasons for 

not including unextracted residues include the following rationale: 1.) It was sufficiently 

demonstrated that bound residues do not desorb into the water column based on aerobic aquatic 

and aerobic soil metabolism laboratory studies, where exhaustive methods of extraction were 

used (MRID Nos. 48399920, 48399927, and 48399929), 2.) Unextracted residues comprised of 

a negligible amount of the material balance based on the anaerobic aquatic metabolism lab study

(MRID No. 48399930), and 3.) Inclusion of unextracted residues on eroded soil particles input 

into the sediment layer had no effect on the pore water EECs since input parameter half-lives 

with and without the residues were similar. Therefore, uncertainties related to the identity of 

unextracted residues should have no impact on this risk assessment.

 Aquatic Plants

Aquatic plant toxicity data are available for one species of vascular plant and four species of 

non-vascular algal organisms. For both vascular and non-vascular aquatic plants, the non-listed 

species RQ is derived by a comparison of the peak EEC to the EC50 of the toxicity study while 

the listed species RQ is derived by a comparison of the peak EEC to the NOAEC of the study. 
79

The LOC for both measures is 1. For non-vascular aquatic plants, the non-listed LOC was 

exceeded for all proposed uses of fenpyrazamine except almonds and pistachios with the 

RQs ranging from 1.30 – 7.87 indicating the potential for toxic effects to this taxa. For 

listed aquatic vascular plants, the LOC was exceeded for every proposed use of 

fenpyrazamine with RQs ranging from 1.51 – 17.67, indicating the potential for toxic 

effects to this taxa. Vascular aquatic plants were substantially less sensitive and there were no 

listed or non-listed LOC exceedances for all proposed uses of fenpyrazamine. Conservative 

EECs resulting from excluding hydrolysis as a degradation pathway given fenpyrazamine’s 

uncertainties of hydrolysis under environmentally relevant conditions are also applicable for 

aquatic plants in this case particularly due to its impact between applications. As a result, peak 

EECs may be substantially lower when considering hydrolysis as a viable degradation pathway. .

Additional non-vascular aquatic plant toxicity studies were submitted for two degradation 

products of fenpyrazamine. Studies conducted on the freshwater green algae 

(Pseudokirchneriella subcapita) using the degradates S-2188-DC and S-2188-OH (MRIDs 

48400019 and 48400020, respectively). Both studies determined that the degradates that were 

tested were approximately 150 times less toxic to freshwater green algae than parent 

fenpyrazamine by 3 orders of magnitude for-2188-DC and S-2188-OH (based on EC50 values). 

As the NOAEC value was non-definitive for parent fenpyrazamine freshwater green algae study, 

the EC05 of 0.029 mg a.i/L was used which is approximately 55 times more sensitive than the 

most sensitive NOAEC from both degradation product studies (1.6 mg a.i/L). Given the varying 

sensitivities of freshwater green algae to parent fenpyrazamine and two of its degradates, the 

estimated listed and non-listed RQs would be significantly less for these degradation products 

than those estimated for parent fenpyrazamine. Biodegradation and abiotic degradation of 

fenpyrazamine in the water column and availability of degradate products to runoff as described 

above for fish species also suggest that exposure of degradate residues will not cause adverse 

impacts to aquatic plants.

7.2.2 Risks to Terrestrial Animals 

a. Potential for Acutely Toxic Exposures 

 Birds

The analysis conducted in risk estimation determined there to be acute dose-based risk to small 

and medium sized birds depending on the food item and crop use of fenpyrazamine. RQs 

ranged from <0.0004 – <0.53, which marginally exceeds the acute non-listed species LOC of 

0.5. These RQ values are based on the most sensitive LD50 value available (> 2,000 mg a.i./kg 

bw for the canary and northern bobwhite quail (Table 26). Acute dietary-based RQs ranged 

from <0.05 – <0.15 with the high end of the range marginally exceeding the endangered 

species LOC of 0.1 (ornamental use, Table 27). These RQs values are also based on the most 

sensitive LD50 value available, which is also a non-definitive endpoint (LC50 >4430 ppm). Only

upper bound (non-definitive) RQs could be determined because no treatment related mortality 

occurred at the highest dose tested in the available toxicity studies (i.e., non-definitive LD50/LC50

values). A review of the acute oral studies for sub lethal effects also indicates no treatmentrelated effects on endpoints such as food consumption, body weight and behavior. A review of 
80

the subacute dietary studies shows a significant reduction (p<0.05) in mean body weight gain as 

compared to the negative control in the three highest treatment concentrations for the bobwhite 

study and the highest treatment concentration for the mallard study. Despite the uncertainty in 

non-definitive endpoints, these estimates are still useful in risk assessment as they give an 

indication of where potential acute risk to birds may be a concern

 Mammals

Similar to birds, acute dose-based risks to mammals are considered low as indicated by 

acute RQs of <0.0003 to <0.15 (Table 28). These RQ values are based the most sensitive acute 

toxicity endpoint available (>2000 mg a.i/kg bw for the rat (Table 9). Only upper bound (nondefinitive) RQs could be determined because no treatment related mortality occurred at the 

highest dose tested in the available toxicity studies (i.e., non-definitive LD50 values). A review 

of the acute oral studies for sub lethal effects also indicates no treatment-related effects on 

endpoints such as food consumption, body weight and behavior. 

b. Potential for Chronically Toxic Exposures

 Birds

Chronic dietary-based RQs for birds (0.06 - 2.72; Table 27) indicate chronically toxic 

exposure to fenpyrazamine with all proposed uses except almonds and pistachios (for 

which the chronic RQ on short grass approaches the LOC at 0.94). Chronic dietary-based 

risk exceeds the LOC for birds ingesting short and tall grass as well as broadleaf plants exposed 

to fenpyrazamine resulting from the ornamental use, and from ingesting only short grass for all 

other uses (except almonds and pistachios). These chronic RQs are based on a dietary NOAEL 

of 248 ppm for the northern bobwhite quail (MRID 48400014) based on effects to hatching body 

weight (day 14) which occurred at the LOAEL of 495 ppm in the diet. It is noted that while

significant effects (p<0.05) to hatching weight at day 14 occurred at the two highest treatment 

concentrations (495 and 978 ppm), the percent reduction from the negative control was 6.2 and 

4.9%, respectively which is considered modest in terms of a biological effect. 

 Mammals 

Chronic dose-based risks associated with mammalian consumption of fenpyrazamine 

exposed food items are indicated in this assessment, with chronic RQs ranging from 0.01 to 

3.66 (Table 29). Chronic risks are identified for all size classes of mammals considered (15, 35 

and 1000g) for the proposed use on ornamentals only and for the small and medium sized class 

mammals for all other uses (for mammals eating short grass). Small and medium sized 

mammals ingesting fenpyrazamine exposed broadleaf plants are in exceedance of the LOC for 

the strawberries, ginseng, and ornamental use and tall grass for the ornamental use only. These 

RQ values are based on a NOAEL of 1000 ppm in the diet (73.7 mg a.i/kg bw) identified for the 

Norway rat (MRID 48400127). The LOAEL from this study was 3000 ppm in the diet based on 

reduced number of implantation sites. Significant (p<0.05) effects also included increased post 

natal loss and body weight reduction in the highest treatment level (3000 ppm). 
81

 Non-target beneficial insects and other non-target terrestrial organisms

The potential exposure of honeybees to pesticides is assessed qualitatively based on laboratory

data and if available, field data. There is a small potential for exposure via transport within the 

plant to pollen and nectar. It is noted that fenpyrazamine is classified as practically non-toxic to 

honeybee (acute contact LD50 >100 ug a.i/bee and an acute oral LC50 of >100 a.i/bee). Clinical 

sings of toxicity included bees showing lethargic symptoms at varying numbers that increased 

with concentration in the acute contact toxicity study. While conceptually potential routes of 

exposure exist for fenpyrazamine to honeybees and other insect pollinators, the very low toxicity

of fenpyrazamine to honeybees suggest that this route of exposure is not likely to be a concern.

An acute toxicity study was also submitted for the earthworm which showed no significant

effects on mortality. Sublethal effects included effects on body weight which was reduced at all

but the highest treatment concentration and lethargy observed in earthworms in the highest 

treatment concentration.

7.2.3 Risks to Terrestrial Plants 

Seedling emergence and vegetative vigor studies are available to estimate RQs for listed and 

non-listed terrestrial plants. The results of TerrPlant indicate an exceedance of the LOC of 1 for 

listed dicot species in semi-aquatic plants, and listed monocots in semi-aquatic as well as listed 

dicots in dry areas and those resulting from spray drift for the ornamental use only. RQs for both 

listed and non-listed plants were derived from the use of non-definitive endpoints. For non-listed 

plants, for which the EEC is compared to the EC25 value, both the seedling emergence and 

vegetative vigor studies had a determined EC25 value of >0.53 lbs a.i/A due to a lack of effects. 

The NOAEC for the vegetative vigor study was also the highest treatment concentration (0.53 

lbs a.i/A). For the seedling emergence study, the NOAEC could not be definitively determined 

for the most sensitive dicot based on effects at the lowest treatment concentration on biomass 

(dry weight, NOAEC of <0.035 lbs a.i/A). In the event a NOAEC being non-definitive, EFED 

policy is to use the EC05 for that endpoint. In this case however, although the statistical 

regression model was able to converge, the model determined the EC05 to be 0.0. As a result, 

the value of 0.035 was used to estimate RQs for listed dicot in the TerrPlant model with the RQs 

being preceded by a “>” sign to signify the RQs may lie higher than this estimated value but to 

what extent is uncertain.

7.2.4 Review of Incident Data 

As fenpyrazamine has not been previously approved for use in the United States, there are no 

incident reports for this chemical.

7.2.5 Threatened and Endangered Species Concerns 

For listed species assessment purposes, the action area is considered to be the area affected 
82

directly or indirectly by the Federal action and not merely the immediate area involved in the 

action. At the initial screening-level, the risk assessment considers broadly described taxonomic 

groups and so conservatively assumes that list species within those broad groups are collocated 

within the pesticide treatment area. This means that terrestrial plants and wildlife are assumed to 

be located on or adjacent to the treated site and aquatic organisms are assumed to be located in a 

surface water body adjacent to the treated site. The assessment also assumes that the listed

species are located within an assumed area which has the relatively highest potential exposure to 

the pesticide, and that exposures are likely to decrease with distance from the treated area. 

If the assumptions associated with the screening-level action area result in RQs that are below 

the listed species LOCs, “no effect,” determination conclusion may be made with respect to 

listed species in that taxa (for direct effects), and no further refinement of the action is necessary. 

Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no 

concern for indirect effects upon listed species that depend upon the taxonomic group as a 

resource. However, in situations where the screening assumptions lead to RQs in excess of the 

listed species LOCs for a given taxonomic group, a potential “may affect,” conclusion exists and 

may be associated with direct effects on listed species belonging to that taxonomic group or may

extend to indirect effects upon listed species that depend on that taxonomic group as a resource. 

In such cases, additional information on the biology of the listed species, the locations of these 

species, and the locations of use sites could be considered along with available information on 

the fate and transport properties of the pesticide to determine the extent to which screening 

assumptions regarding an action area apply to a particular listed organism. These subsequent 

refinement steps could consider how this information would impact the action area for a 

particular listed organism and may potentially include areas of exposure that are downwind and 

downstream of the pesticide use site. 

In conducting a screen for indirect effects, direct effects LOCs for each taxonomic group are 

used to make inferences concerning the potential for indirect effects upon listed species that rely 

upon non-listed organisms in these taxonomic groups as resources critical to their cycle. 

Pesticide use scenarios resulting in RQs that are below all direct effect listed species LOCs for 

all taxonomic groups assessed are considered of no concern for risks to listed species either by 

direct or indirect effects.

For fenpyrazamine, the potential direct effects to listed species should they co-occur with 

application sites are indicated for mammals (acute and chronic toxicity) and birds (acute and 

chronic toxicity) based on ingestion of fenpyrazamine contaminated food items. Listed species 

LOCs are exceeded for any other taxonomic group assessed (aquatic animals, aquatic plants, 

nontarget invertebrates). For the maximum proposed fenpyrazamine application rates, there may

be a potential concern for direct effects to the following groups of organisms:

• Birds 

• Mammals

• Terrestrial-phase reptiles

• Terrestrial-phase amphibians
83

A spatial co-occurrence analysis would be necessary to delineate the action area.

7.2.6 Description of Assumptions, Limitations, Uncertainties, Strengths and 

Data Gaps 

There are a number of areas of uncertainty in the aquatic and terrestrial risk assessments. The 

toxicity assessment for terrestrial and aquatic plants and animals is limited by the number of 

species tested in the available toxicity studies. Use of toxicity data on representative species 

does not provide information on the potential variability in susceptibility to acute and chronic 

exposures. 

a. Incidental Pesticide Releases Associated with Use 

This risk assessment is based on the assumption that the entire treatment area is subject to 

fenpyrazamine application at the rates specified on the label. In reality, there is the potential for 

uneven application of fenpyrazamine through such plausible incidents as changes in calibration 

of application equipment, spillage, and localized releases at specific areas of the treated field that 

are associated with specifics of the type of application equipment.

b. Exposure for Aquatic Species 

This Tier II risk assessment relies on best available estimates of environmental fate and 

physicochemical properties, maximum application rate of fenpyrazamine, maximum number of 

applications, and the shortest interval between applications. However, several modeling

limitations are noted and should be considered in interpreting the results of this aquatic risk 

assessment. 

• The frequency at which actual fenpyrazamine uses approach the use estimates modeled is 

dependent on resistance to the fungicide, timing of applications, and market forces. In 

general, model output values represent the upper bound estimates of concentrations that 

might be observed in surface water due to the application of fenpyrazamine, given 

available data and model limitations.

• Although there are uncertainties associated with using the standard PRZM/EXAMS 

runoff scenario (10 ha field draining into 20,000 m3pond with no outlet) for an aquatic 

exposure assessment, it is designed to represent pesticide exposure from an agricultural 

watershed impacting a vulnerable aquatic environment. Extrapolating the risk 

conclusions from this standard pond scenario to a specific body of water of different 

dimensions, may either underestimate or overestimate the potential risks.

• Major uncertainties associated with the standard runoff scenario include the physical 

construct of the watershed and representation of vulnerable aquatic environments for 

different geographic regions. The physicochemical properties (pH, redox conditions, 

etc.) of the standard farm pond are based on a Georgia farm pond. These properties are 
84

likely to be regionally specific because of local hydrogeological conditions. Any

alteration in water quality parameters may impact the environmental behavior of a 

pesticide. The farm pond represents a well mixed, static water body. Because the farm 

pond is a static water body (no flow through), it does not account for pesticide removal 

through flow through or water releases. The lack of flow through the farm pond provides 

an environmental condition for accumulation of persistent pesticides. The assumption of 

uniform mixing does not account for stratification due to thermoclines (e.g., seasonal 

stratification in deep water bodies). Additionally, the dimensions of the standard runoff 

scenario assume a watershed area to water body volume ratio of 10 ha: 20,000m3. This 

ratio is recommended to maintain a sustainable constructed pond in the Southeastern 

United States. The use of higher watershed area to water body volume ratios (as 

recommended for sustainable ponds in drier regions of the United States) may lead to 

higher pesticide concentrations when compared to the standard watershed area to water 

body volume ratio.

• The standard runoff scenario assumes uniform soils and agronomic management 

practices across the standard 10 hectare field. Soils can vary substantially across even 

small areas; this variation is not reflected in the model simulations. Additionally, the 

impact of unique soil characteristics and soil management practices (e.g., tile drainage) 

are not considered in the standard runoff scenario. The assumption of uniform site and 

management conditions is not expected to represent some site-specific conditions. 

Extrapolating the risk conclusions from the standard pond scenario to other aquatic 

habitats (e.g., marshes, streams, creeks, and shallow rivers, intermittent aquatic areas) 

may either underestimate or overestimate the potential risks in those habitats.

• Aquatic EECs are based on a conservative scenario the entire watershed area is impacted 

by a treated crop. However, in reality, only a percentage of the watershed is impacted by 

a crop treatment.

• For an acute risk assessment, there is no averaging time for exposure. A peak 

concentration, with a 1 in 10 year return frequency, is assumed. The use of the peak 

concentration in the calculation of risk quotients assumes that exposure is sufficient to 

elicit acute effects comparable to those observed over more protracted exposure periods 

tested in the laboratory, typically 48 to 96 hours. In the absence of data regarding timeto-toxic event analyses and latent responses to peak exposure, the degree to which risk is 

overestimated cannot be quantified.

There are also several significant uncertainties with the environmental fate profile of 

fenpyrazamine. These uncertainties can impact estimation of acute and chronic EECs in surface 

water, benthic pore water, as well as sediment.

The first major uncertainty concerns fenpyrazamine’s rate of hydrolysis in the environment. The 

existing hydrolysis study suggests that fenpyrazamine degrades over all environments, especially 

in alkaline environments, with metabolites S-2188-OH and S-2188-DC detected (MRID No. 

48399923). This is also evident from the aerobic aquatic metabolism study (MRID No. 
85

48399929), which also shows a trend of decreased half-lives at higher pHs. However, 

environmentally relevant hydrolysis data were not provided to the Agency for neutral 

environments (pH7). . In the absence of adequate data, EFED conservatively assumed that the 

chemical persists to hydrolysis at pH 7. This uncertainty could be addressed by a guideline 

hydrolysis study conducted at environmentally relevant temperatures. The study may be used to 

recalculate aquatic EECs more representative of fenpyrazamine levels in the environment. 

Additional data can especially impact future new uses with high application rates resulting in 

higher risk quotients. However, no additional data will be requested at this time.

A second significant uncertainty relates to the limited systems evaluated in the anaerobic aquatic 

study (MRID Nos. 48399930). Only one system was evaluated in each study. Additional 

studies could provide a more robust representation for the degradation of fenpyrazamine in

suboxic environments. Therefore, more refined aquatic EECs, especially related to benthic 

organisms, may result considering that the single half-life values were multiplied by three as a 

conservative default to address this uncertainty. However, no additional data will be requested at 

this time.

A third uncertainty regards unextracted residues incorporated in soil or sediment layers. In soil,

unextracted residues accounted for approximately up to 70 percent of applied in two alkaline 

soils in aerobic soil metabolism studies (MRID No. 48399920). In water, unextracted residues in 

sediment from the Calwich Abbey, UK study sample accounted for up to 48.4 percent of applied. 

Despite these large levels of unextracted residues detected in aerobic soil and aerobic aquatic 

metabolism, unextracted residues were excluded from the expression of the “total residues of 

concern” and, therefore, from the aquatic EECs. First, it was sufficiently demonstrated that 

bound residues do not desorb into the water column based on aerobic aquatic and aerobic soil 

metabolism laboratory studies, in which exhaustive methods of extraction were used (MRID 

Nos. 48399920, 48399927, and 48399929). Second, unextracted residues comprised of a 

negligible amount of the material balance based on the anaerobic aquatic metabolism lab study

(MRID No. 48399930). Third, inclusion of unextracted residues incorporated in eroded soil

input into the sediment layer had no effect on the pore water EECs since the aerobic soil 

metabolism half life parameterization without the unextracted residues was generally similar. 

Therefore, uncertainties related to the identity of unextracted residues should have no impact on 

EECs or the risk conclusions in this risk assessment. However, it should be noted that 

unextracted residues are likely bonded chemically to the humin matrices within the soil and 

sediment layers. Soil-water partition coefficients of fenpyrazamine and degradates as well as 

inconsistencies in the amount of unextracted residues between the aerobic and anaerobic aquatic 

metabolism studies suggest that unextracted residues are not forming due to sorbtion of 

fenpyrazamine.

A fourth uncertainty which exists is that water-sediment systems with variable pHs were 

evaluated in the aerobic aquatic metabolism study (MRID No. 48399929). Since degradation is 

much different between acidic and alkaline conditions, it appears that degradation is mediated 

pH. Additional soil-sediment systems evaluated over a similar pH range would provide insight 

on the effect of degradation solely on microbial activity.
86

The fifth uncertainty concerns the lacking information on the representativeness on foreign soils 

evaluated in aerobic soil metabolism and batch equilibrium studies to domestic soils. Regardless 

of these deficiencies, the studies conducted on soils in the United Kingdom in batch equilibrium 

and aerobic soil metabolism studies (MRID Nos. 48399919 and 48399920, respectively) were 

considered since soils from the UK are traditionally similar in their physical chemical 

characteristics to soils that exist within the United States.

c. Exposure for Terrestrial Species 

This risk assessment relies on the best available estimates of environmental fate and 

physicochemical properties, maximum application rate of fenpyrazamine, maximum number of 

applications, and the shortest interval between applications. However, several uncertainties and 

model limitations are noted and should be considered in interpreting the results of this terrestrial 

risk assessment. 

 Dietary Exposure

For screening terrestrial risk assessments, a generic bird or mammal is assumed to consume 

100% of its diet on food which is contaminated with fenpyrazamine from the application site. 

This assumption may lead to an overestimation of exposure to species that do not occupy the 

treated field. The actual habitat requirements of any particular terrestrial species are not 

considered, and it is assumed that species occupy, exclusively and permanently, the treated area 

being modeled. This assumption leads to a maximum level of exposure in the risk assessment. 

 Dermal Exposure

The screening assessment does not consider fenpyrazamine dermal exposure to terrestrial 

organisms. The Agency is actively pursuing modeling techniques to account for dermal exposure 

via direct application of spray and by incidental contact with contaminated vegetation, soil and 

water.

 Inhalation Exposure

Preliminary results of the screening level tool STIR (described earlier in this assessment) 

indicate that inhalation exposure alone is not expected to be a significant route of exposure for 

fenpyrazamine to wildlife. The input and output file can be found in Appendix B.

 Drinking Water Exposure 

Preliminary results of the screening level tool SIP (described earlier in this assessment) indicate 

that drinking water exposure alone is not expected to be a significant route of exposure for 

fenpyrazamine to wildlife. The input and output file can be found in Appendix C.

d. Effects Assessment 
87

As the data available to support the terrestrial and aquatic effects assessment for fenpyrazamine 

is largely complete, the primary uncertainty with the available data is the presence of nondefinitive endpoints for several taxa. Non-definitive endpoints were reached for acute oral and 

dietary studies for birds, acute oral data for rats, acute toxicity studies for honey bees, acute and 

chronic studies for estuarine/marine fish, chronic freshwater and estuarine/marine sediment 

toxicity studies, and terrestrial plant studies. However the non-definitive endpoints were “<,” 

values (which would yield a “>” RQ) only for chronic estuarine/marine fish, freshwater and 

estuarine/marine sediment toxicity studies, and the terrestrial plant study for seedling emergence. 

In these cases, it is uncertain where the actual RQ falls as the estimates are unbounded, or rather 

bounded on only one end. As a result, estimates of chronic toxicity to estuarine/marine fish and 

sediment toxicity studies are in exceedances of the chronic LOC for some uses, but even those 

uses that are not in exceedance, it is an uncertainty where the actual RQ would fall. Despite this 

uncertainty, the estimated chronic RQs could be refined with a suitable hydrolysis study as the 

assumptions that are made in its absence lead to conservative estimates of 1-in-10 year 60 day

averages that are used to estimate chronic LOCs. This is detailed further in Section 7.2.6.b. 

 Age Class and Sensitivity of Effects Thresholds 

It is generally recognized that test organism age may have a significant impact on the observed 

sensitivity to a toxicant. The screening risk assessment acute toxicity data for fish are collected 

on juvenile fish and aquatic invertebrate acute testing is performed on recommended immature 

age classes. Similarly, acute dietary testing with birds is also performed on juveniles, with 

mallard being 5-10 days old and quail at 10-14 days of age. 

Testing of juveniles may overestimate the toxicity of direct acting pesticides in adults. As 

juvenile organisms do not have fully developed metabolic systems, they may not possess the 

ability to transform and detoxify xenobiotics equivalent to the older/adult organism. The 

screening risk assessment has no current provisions for a generally applied method that accounts 

for this uncertainty. In so far as the available toxicity data may provide ranges of sensitivity 

information with respect to age class, the risk assessment uses the most sensitive life-stage 

information as the conservative screening endpoint.

 Lack of Effects Data for Amphibians and Reptiles 

Currently, toxicity studies on amphibians and reptiles are not required for pesticide registration. 

Since these data are lacking, the Agency uses fish as surrogates for aquatic phase amphibians and 

birds as surrogates for terrestrial phase amphibians and reptiles. If other species are more or less 

sensitive to fenpyrazamine than the surrogates, risks may be under- or overestimated, 

respectively. The Agency is not limited to a base set of surrogate toxicity information in 

establishing risk assessment conclusions. The Agency also considers toxicity data on nonstandard test species when available. Further research is needed to determine whether, in 

general, reptiles and terrestrial-phase amphibians are suitably represented by bird species in 

assessing risks for fenpyrazamine and fish are an appropriate surrogate for aquatic-phase 

amphibians. 
88

 Use of the Most Sensitive Species Tested 

Although the screening risk assessment relies on a selected toxicity endpoint from the most 

sensitive species tested, it does not necessarily mean that the selected toxicity endpoints reflect 

sensitivity of the most sensitive species existing in a given environment. The relative position of 

the most sensitive species tested in the distribution of all possible species is a function of the 

overall variability among species to a particular chemical. The relationship between the 

sensitivity of the most sensitive tested species versus wild species (including listed species) is 

unknown and a source of significant uncertainty. In addition, in the case of listed species, there is 

uncertainty regarding the relationship of the listed species' sensitivity and the most sensitive 

species tested. 

8. IDENTIFICATION OF DATA GAPS

Environmental Fate and Exposure

Despite numerous uncertainties, the Agency is not asking for any additional studies at this time. 

Please refer to Section 7.2.6b for further details.

Ecological Effects

The ecological toxicity database is essentially complete. However the ELS study for sheepshead 

minnow and the sediment toxicity studies for Chironomus riparius and Leptocheirus plumulosus

yielded non-definitive endpoints which raises uncertainty in the estimation of RQs to these 

organisms. The need for new studies may be waived if uncertainties in the hydrolysis and soil 

metabolism studies can be worked out as lower estimates of aquatic exposure may result. 

However, the Agency is not asking for any additional studies at this time.
89

9. REFERENCES

 Environmental Fate Studies 

MRID Author(s) Year Title 

Hydrolysis

48399923 Lewis, C. 2007 [Carbon 14]S-2188: Hydrolytic Stability. Project Number: 

200700497, 0333/257, QNM/0017. Unpublished study 

prepared by Covance Laboratories, Ltd. 184 p.

Aqueous Photolysis

48399924 Lewis, C.; Troth, K. 2007 [Carbon 14]S-2188: Photodegradation and Quantum Yield 

in Sterile, Aqueous Solution. Project Number: 200800010, 

0333/258, QNM/0029. Unpublished study prepared by 

Covance Laboratories, Ltd. 195 p.

Air Photolysis

48399925 Liney, P.; Jarvis, T. 2009 S-1288 - Stability in Air. Project Number: 200900604, 

SU25005, QNM/0032. Unpublished study prepared by 

Exponent International, Ltd. 7 p.

Soil Photolysis

48399926 Lewis, C.; Troth, K. 2007 [Carbon 14]S-2188: Photodegradation on a Soil Surface. 

Project Number: 200700495, 0333/259, QNM/0020. 

Unpublished study prepared by Covance Laboratories, Ltd. 

115 p.

Batch Equilibrium

48399919 Lewis, C.; Scholey, 

A.

2006 [Carbon 14]S-2188: Adsorption/Desorption in Soil. Project 

Number: 200600614, 0333/255, QNM/0012. Unpublished 

study prepared by Covance Laboratories, Ltd. 71 p.

48399922 Gohre, K. 2008 S-2188: Soil Adsorption/Desorption. Project Number: 

200800201, VP/29272. Unpublished study prepared by 

Valent Dublin Laboratory. 90 p.

Aerobic Soil Metabolism

48399920 Lewis, C.; Troth, K. 2006 S-2188: Aerobic Soil Metabolism and Degradation. Project 

Number: 200700498, 0333/256, QNM/0016. Unpublished 

study prepared by Covance Laboratories, Ltd. 127 p.

48399927 Gohre, K. 2008 S-2188: Degradation Under Aerobic Conditions in Soil. 

Project Number: VP/29719, 200800286. Unpublished study 

prepared by Valent Dublin Laboratory. 169 p.

Aerobic Aquatic Metabolism

48399929 Lewis, C.; Troth, K. 2007 [Carbon 14] S-2188: Degradation and Retention in WaterSediment Systems. Project Number: 200800017, 0333/260, 

QNM/0028. Unpublished study prepared by Covance 

Laboratories, Ltd. 188 p.
90

MRID Author(s) Year Title 

Anaerobic Aquatic Metabolism

48399930 Gohre, K. 2008 S-2188: Degradation Under Anaerobic Aquatic Conditions. 

Project Number: 200800200, VP/30465. Unpublished study 

prepared by Valent Dublin Laboratory. 152 p.

Fish BCF

48400005 Panthani, A.; 

Herczog, K.

2007 Bioconcentration of [Carbon 14] S-2188 by Bluegill 

Sunfish (Lepomis macrochirus). Project Number: 

200700494, 019492/1, QNM/0018. Unpublished study 

prepared by Ricerca Biosciences, LLC. 241 p.

Terrestrial Field Dissipation

48399931 Kowalsky, J. 2010 Terrestrial Field Soil Dissipation of S-2188 on Bare Ground 

in California (2006). Project Number: 201000303, 30311. 

Unpublished study prepared by Valent Dublin Laboratory. 

251 p.

48399932 Green, C. 2010 Terrestrial Field Soil Dissipation of S/2188 on Bare Ground 

in California (2009). Project Number: 33068. Unpublished 

study prepared by Valent Dublin Laboratory. 196 p.

48399933 Kowolsky, J. 2010 Terrestrial Field Soil Dissipation of S-2188 on Bare Ground 

in Idaho. Project Number: 201000313, 30309. Unpublished 

study prepared by Valent Dublin Laboratory. 264 p.

48399934 Kowolsky, J. 2010 Terrestrial Field Soil Dissipation of S-2188 on Bare Ground 

in New York. Project Number: 201000302, 30296. 

Unpublished study prepared by Valent Dublin Laboratory. 

266 p.

Storage Stability

48399921 Peatman, M. 2008 S-2188: Storage Stability of Residues in EU Soil Stored 

Deep Frozen. Project Number: 200900605, 0333/268, 

QNM/0036. Unpublished study prepared by Covance 

Laboratories, Ltd. 35 p.

Environmental Chemistry Method in Water

48399918 Bacher, R. 2008 S-2188: Analytical Method for the Determination in Water. 

Project Number: 200900211, P/1401/G, QNA/0015. 

Unpublished study prepared by PTRL Europe Gmbh. 36 p.

Independent Laboratory Validation for Water ECM

48400034 Dix, M. 2006 S-2188 - Validation of the Analytical Method for the 

Determination of a Test Substance in Aqueous Solutions. 

Project Number: 200600063, 13048/6503, 

ELECTRONIC/COPY. Unpublished study prepared by 

Springborn Smithers Laboratories. 39 p.

Environmental Chemistry Method in Soil/ Independent Laboratory Validation for Soil ECM

48400026 Green, C. 2010 Independent Laboratory Validation of Method RM-45S, 

Determination of S-2188 and S-2188-DC in Soil. Project 

Number: 201000244, 33001. Unpublished study prepared 

by Valent U.S.A. Corporation. 90 p.
91

 Ecological Effects Studies

MRID Author(s) Year Title 

48399935 Hoberg, J.R. 2006 S-2188 Technical Grade- Acute Oral Toxicity Test with the 

Honey Bee (Apis mellifera). Springborn Smithers 

Laboratories, 790 Main Street Wareham, Massachusetts 

02571-1037. Sumitomo Chemical Company, Ltd.

Laboratory Report ID: 13048.6510. 39 p.

48399936 Hara, T. 2008 Acute Immobilization Test of MCNI with Daphnia magna. 

Unpublished study performed by Sumika Technoservice 

Corporation, 2-1, Takatsukasa 4-chome, Takarazuka-City, 

Hyogo 665-0051, Japan. Laboratory report number 

0705EFA. Study sponsored by Sumitomo Chemical 

Corporation. Study completed March 20, 2008. 29 p.

48399937 Hara, T. 2008 Acute Immobilization Test of S-2188-OH with Daphnia 

magna. Unpublished study performed by Sumika 

Technoservice Corporation, 2-1, Takatsukasa 4-chome, 

Takarazuka-City, Hyogo 665-0051, Japan. Laboratory 

report number 0705EDI. Study sponsored by Sumitomo 

Chemical Corporation. Study completed March 20, 2008. 

27 p. 

48399938 Hara, T. 2008 Acute Immobilization Test of S-2188-DC with Daphnia 

magna. Unpublished study performed by Sumika 

Technoservice Corporation, 2-1, Takatsukasa 4-chome, 

Takarazuka-City, Hyogo 665-0051, Japan. Laboratory 

report number 0706EDI. Study sponsored by Sumitomo 

Chemical Corporation. Study completed March 20, 2008. 

32 p. 

48399939 Putt, AE 2006 S-2188 Technical Grade- Acute Toxicity to Water Fleas 

(Daphnia magna) Under Flow-Through Conditions. 

Unpublished study performed by Springborn Smithers 

Laboratories, Wareham, MA. Laboratory report number 

13048.6507. Study sponsored by Sumitomo Chemical 

Corporation. Study completed June 23, 2006. 91 p.

48399940 York, DO 2010 V-10135 T.G. (S-2188 T.G.): Acute Toxicity to Eastern 

Oyster (Crassostrea virginica) Under Flow-Through 

Conditions. Smithers Viscient Laboratories 790 Main 

Street, Wareham, Massachusetts 02571-1037. Laboratory 

Report ID: 12709.6302. 81 p.

48399941 Fournier, A.E 2010 V-10135 T.G. (S-2188 T.G.): Acute Toxicity to Mysid 

(Americamysis bahia) Under Static Conditions, Following 

OPPTS Guideline 850.1035. Smithers Viscient 

Laboratories, 790 Main Street, Wareham, MA 02571-1037. 

Laboratory Report ID: 12709.6303. 82 p.

48399942 Ashida, S. 2008 Acute Toxicity Test of S-2188-DC With Rainbow Trout 

(Oncorhynchus mykiss). Unpublished study performed by 

Sumika Technoservice Corporation, 2-1, Takatsukasa 4-

chome, Takarazuka-City, Hyogo 665-0051, Japan. 

Laboratory report number 0706EFA. Study sponsored by 

Sumitomo Chemical Company and submitted by Valent 

U.S.A. Corporation. Study completed March 20, 2008. 27 

p.
92

MRID Author(s) Year Title 

48399943 Ashida, S. 2008 Acute Toxicity Test of S-2188-OH With Rainbow Trout 

(Oncorhynchus mykiss). Unpublished study performed by 

Sumika Technoservice Corporation, 2-1, Takatsukasa 4-

chome, Takarazuka-City, Hyogo 665-0051, Japan. 

Laboratory report number 0705EFA. Study sponsored by 

Sumitomo Chemical Company and submitted by Valent 

U.S.A. Corporation. Study completed March 20, 2008. 27 

p.

48399944 Cafarella, MA. 2006 S-2188 Technical Grade- Acute Toxicity to Bluegill 

Sunfish (Lepomis macrochirus) Under Flow-Through 

Conditions. Unpublished study performed by Springborn 

Smithers Laboratories, 790 Main Street, Wareham, 

Massachusetts 02571-1037. Laboratory report number 

13048.6505. Study sponsored by Sumitomo Chemical 

Company and submitted by Valent U.S.A. Corporation. 

Study completed April 14, 2006. 89 p.

48399945 Cafarella, MA. 2006 S-2188 Technical Grade- Acute Toxicity to Rainbow Trout 

(Oncorhynchus mykiss) Under Flow-Through Conditions. 

Unpublished study performed by Springborn Smithers 

Laboratories, 790 Main Street, Wareham, Massachusetts 

02571-1037. Laboratory report number 13048.6504. Study 

sponsored by Sumitomo Chemical Company and submitted 

by Valent U.S.A. Corporation. Study completed March 30, 

2006. 88 p.

48399946 Fournier, AE. 2010 V-10135 T.G, (S-2188 T.G.) Acute Toxicity to Sheepshead 

Minnow (Cyprinodon variegatus) Under Static Conditions. 

Unpublished study performed by Smithers Viscient 

Laboratories (formerly Springborn Smithers Laboratories), 

Wareham, Massachusetts. Laboratory report number 

12079.6301. Study sponsored by Valent U.S.A. 

Corporation. Study completed November 18, 2010. 77 p.

48400001 Putt, AE. 2006 S-2188 Technical Grade – Full Life-Cycle Toxicity Test 

with Water Fleas, Daphnia Magna under Flow-Through 

Conditions. Unpublished study performed by Springborn 

Smithers Laboratories, Wareham, MA. Laboratory Study 

No. 13048.6508. Study sponsored by Sumitomo Chemical 

Company, Ltd., Tokyo, Japan and submitted by Valent 

U.S.A. Corporation, Walnut Creek, CA. Study initiated 

February 17, 2006 and completed September 27, 2006. 112 

p.

48400002 Lee, M.R 2010 V-10135 T.G. (S-2188 T.G.) – Life-Cycle Toxicity Test 

with Mysids (Americamysis bahia) Following Draft OPPTS 

Guideline 850.1350. Springborn Viscient Laboratories, 790 

Main Street, Wareham, MA 02571-1037. Laboratory 

Report ID: 13845.6109. 150 p.

48400003 Cafarella, M.A 2006 S-2188 Technical Grade – Early Life-Stage Toxicity Test 

with Rainbow Trout (Oncorhynchus mykiss). Unpublished 

study performed by Springborn Smithers Laboratories, 

Wareham, MA. Laboratory Study No. 13048.6506. Study 

sponsored by Sumitomo Chemical Company, Ltd., Tokyo, 

Japan and submitted by Valent U.S.A. Corporation, Walnut 

Creek, CA. Study initiated January 23, 2006 and completed 

September 19, 2006. 111 p. 
93

MRID Author(s) Year Title 

48400004 Lee, M.R 2010

V-10135 T.G. (S-2188 T.G.) Early Life-Stage Toxicity Test 

with Sheepshead Minnow (Cyprinodon variegatus). 

Unpublished study performed by Springborn Smithers 

Laboratories, Wareham, MA. Laboratory Study No. 

12709.6292. Study sponsored by Valent U.S.A. 

Corporation, Walnut Creek, CA. Study initiated December 

9, 2009 and completed October 8, 2010. 87 p.

48400006 Picard, C.R 2010 42

-Day Toxicity Test Exposing Freshwater Amphipods 

(Hyalella azteca) to V-10135 (S-218) Applied to Sediment 

Under Static-Renewal Conditions Following EPA Test 

Methods. Springborn Smithers Laboratories, 790 Main 

Street, Wareham, MA 02571-1037. Valent USA 

Corporation, 1600 Riveria Avenue, Suite 200, Walnut 

Creek, CA 94596-8025. Laboratory Report ID: 12709-

6290. 193 p.

48400007 Putt, A.E 2009

S-2188 Technical Grade – Full Life-Cycle Toxicity Test 

with Sediment-Dwelling Midges (Chironomus riparius) 

Under Static Conditions, Following OECD Guideline 219. 

Springborn Smithers Laboratories, 790 Main Street, 

Wareham, MA 02571-1037. Valent U.S.A. Corporation 

1600 Riveria Avenue, Suite 200 Walnut Creek, CA. 

Laboratory Report ID: 13048.6535. 106 p.

48400008 Picard, C.R 2010

V-10135 (S-2188) – 28-Day Toxicity Test Exposing 

Estuarine Amphipods (Leptocheirus plumulosus) to a Test 

Substance Applied to Sediment Following EPA Test 

Methods. Springborn Smithers Laboratories 790 Main 

Street Wareham, MA 02571-1037. Valent U.S.A. 

Corporation 1600 Riveria Avenue, Suite 200 Walnut Creek, 

CA. Laboratory Report ID: 12709.6291. 121 p. 

48400009 Stafford, J.M 2006

-2188 Technical Grade- Acute Oral Toxicity Test (LD50) 

with Northern Bobwhite Quail (Colinus virginianus). 

Unpublished study performed by Springborn Smithers 

Laboratories, Snow Camp, North Carolina. Laboratory 

Report No. 13048.4104. Study sponsored by Sumitomo 

Chemical Company, Ltd, Tokyo, Japan and submitted by 

Valent USA Corporation. Study initiated December 30, 

2005 and completed April 11, 2006. 50 p.

48400010 Hubbard, P.M 2010

V-10135: An Acute Oral Toxicity Study with the Canary 

(Serinus canaria). Unpublished study performed by 

Wildlife International, Ltd, Easton, Maryland. Laboratory 

Project No. 263-165. Study submitted by Valent USA 

Corporation. Study initiated June 29, 2010 and completed 

September 9, 2010. 46. 

48400011 Stafford, J.M 2006

S-2188 Technical Grade- Dietary Toxicity Test with 

Northern Bobwhite Quail (Colinus virginianus). 

Unpublished study performed by Springborn Smithers 

Laboratories, Snow Camp, North Carolina and Wareham, 

Massachusetts. Laboratory Project ID 13048.4105. Study 

sponsored by Sumitomo Chemical Company, Ltd., Tokyo, 

Japan and submitted by Valent U.S.A. Corporation. Study 

initiation date April 1, 2006; completion date July 3, 2006. 

102 p. 
94

MRID Author(s) Year Title 

48400012 Stafford, J.M 2006 S-2188 Technical Grade- Dietary Toxicity Test with the 

Mallard Duck (Anas platyrhynchos). Unpublished study 

performed by Springborn Smithers Laboratories, Snow 

Camp, North Carolina and Wareham, Massachusetts. 

Laboratory Project ID 13048.4106. Study sponsored by 

Sumitomo Chemical Company, Ltd., Tokyo, Japan and 

submitted by Valent U.S.A. Corporation. Study initiation 

date June 12, 2006; completion date September 28, 2006. 

99 p.

48400013 Stafford, J.M 2008 S-2188 Technical Grade- Reproductive Toxicity Test with 

Mallard Ducks (Anas platyrhynchos) Following OPPTS 

850.2300 and OECD 206. Unpublished study performed by 

Springborn Smithers Laboratories, Wareham, 

Massachusetts. Laboratory Project ID 13048.4108. Study 

sponsored by Sumitomo Chemical Company, Ltd., Tokyo, 

Japan and submitted by Valent U.S.A. Corporation. Study 

initiation date May 29, 2007; completion date April 25, 

2008. 179 p. 

48400014 Stafford, J.M 2008 S-2188 Technical Grade- Reproductive Toxicity Test with 

Northern Bobwhite (Colinus virginianus) Following 

OPPTS 850.2300 and OECD 206. Unpublished study 

performed by Springborn Smithers Laboratories, Snow

Camp, North Carolina and Wareham, Massachusetts. 

Laboratory Project ID 13048.4107. Study sponsored by 

Sumitomo Chemical Company, Ltd., Tokyo, Japan and 

submitted by Valent U.S.A. Corporation. Study initiation 

date January 19, 2007; completion date April 25, 2008. 177 

p.

48400015 Hoberg, J.R 2006 S-2188 Technical Grade- Acute Contact Toxicity Test with 

the Honey Bee (Apis mellifera). Springborn Smithers 

Laboratory 790 Main Street Wareham, Massachusetts 

02571-1037. 40 p.

48400016 Porch, J.R 2010 V-10135: A Toxicity Test to Determine the Effects of the 

Test Substance on Seedling Emergence of Ten Species of 

Plants. Unpublished study performed by Wildlife 

International, Ltd., Easton, Maryland. Laboratory Project 

Number: 263-166. Study sponsored by Valent U.S.A. 

Corporation. Study completed September 15, 2010. 147 p. 

48400017 Porch, J.R 2010 A Toxicity Test to Determine the Effects of the Test 

Substance on Vegetative Vigor of Ten Species of Plants. 

Unpublished study performed by Wildlife International, 

Ltd., Easton, Maryland. Laboratory Project Number: 263-

167. Study sponsored by Valent U.S.A. Corporation. 

Study completed December 14, 2010. 167 p.

48400018 Softcheck, K.A 2010 7-Day Toxicity Test with Duckweed (Lemna gibba) 

Following OPPTS Draft Guideline 850.4400. Unpublished 

study performed by Smithers Viscient Laboratories, 790 

Main Street, Wareham, Massachusetts 02571-1037. 

Laboratory report number 12709.6305. Study sponsored by 

Valent U.S.A. Corporation. Study completed November 8, 

2010. 110 p. 
95

MRID Author(s) Year Title 

48400019 Matsuura, Y. 2008 Growth Inhibition Test of S-2188-DC with the Freshwater 

Green Alga (Pseudokirchneriella subcapitata). 

Unpublished study performed by Sumika Technoservice 

Corporation, 2-1, Takatsukasa 4-chrome, Takarazuka-City, 

Hyogo 665-0051, Japan. Laboratory report number 

0706EAI. Study sponsored by Valent U.S.A. Corporation. 

Study completed March 19, 2008. 37 p.

48400020 Matsuura, Y. 2008 Growth Inhibition Test of S-2188-OH with the Freshwater 

Green Alga (Pseudokirchneriella subcapitata). 

Unpublished study performed by Sumika Technoservice 

Corporation, 2-1, Takatsukasa 4-chrome, Takarazuka-City, 

Hyogo 665-0051, Japan. Laboratory report number 

0705EAI. Study sponsored by Valent U.S.A. Corporation. 

Study completed March 19, 2008. 37 p.

48400021 Hoberg, J.R 2008 Growth Inhibition Test of S-2188-DC with the Freshwater 

Green Alga (Pseudokirchneriella subcapitata). 

Unpublished study performed by Springborn Smithers 

Laboratories, Wareham, Massachusetts 02571-1037. 

Laboratory report number 13048.6509. Study sponsored by 

Valent U.S.A. Corporation. Study completed April 12, 

2008. 109 p. 

48400022 Softcheck, K.A 2010 V-10135 T.G. (S-2188 T.G.) 96-Hour Toxicity Test with 

the Marine Diatom, Skeletonema costatum, Following 

OPPTS Draft Guideline 850.5400. Unpublished study 

performed by Smithers Viscient Laboratories, Wareham, 

Massachusetts 02571-1037. Laboratory report number 

12079.6307. Study sponsored by Valent U.S.A. 

Corporation. Study completed November 18, 2010. 89 p.

48400023 Softcheck, K.A 2010 V-10135 T.G. (S-2188 T.G.) 96-Hour Toxicity Test with 

the Freshwater Diatom, Navicula pelliculosa, Following 

OPPTS Draft Guideline 850.5400. Unpublished study 

performed by Smithers Viscient Laboratories, Wareham, 

Massachusetts 02571-1037. Laboratory report number 

12079.6304. Study sponsored by Valent U.S.A. 

Corporation. Study completed November 17, 2010. 89 p. 

48400024 Softcheck, K.A 2010 V-10135 T.G. (S-2188 T.G.) 96-Hour Toxicity Test with 

the Freshwater Blue-Green Alga, Anabaena flos-aquae, 

Following OPPTS Draft Guideline 850.5400. Unpublished 

study performed by Smithers Viscient Laboratories, 

Wareham, Massachusetts 02571-1037. Laboratory report 

number 12079.6306. Study sponsored by Valent U.S.A. 

Corporation. Study completed December 2, 2010. 93p. 

48400025 Teixeira, D 2006 S-2188 Technical Grade- Acute Toxicity to Earthworms 

(Eisenia fetida). Unpublished study performed by 

Springborn Smithers Laboratories, Wareham, 

Massachusetts 02571-1037. Laboratory report number 

13048.6512. Study sponsored by Valent U.S.A. 

Corporation. Study completed April 11, 2006. 38 p.
96

Open Literature and Government Reports 

Burns, Lawrence, 1997. Exposure Analysis Modeling System (EXAMS): User Manual and 

System Documentation. Ecosystem Research Division, National Exposure Research Laboratory. 

U. S. Environmental Protection Agency, Athens, GA.

Carsel, R. F., J. C. Imhoff, P. R. Humel, J. M. Cheplick, and A. S. Donigian, Jr. 1997. PRZM-3, 

A Model for Predicting Pesticide and Nitrogen Fate in the Crop Root and Unsaturated Zones: 

User’s Manual for Release 3.0. National Exposure Research Laboratory, Office of Research and 

Development, U. S. Environmental Protection Agency, Athens, GA.

Fungicide Resistance Action Committee. FRAC code list: Fungicides sorted by mode of action. 

2009. http://www.frac.info/frac/publication/anhang/FRAC_CODE_LIST.pdf 

Terrestrial Residue Exposure Model (T-REX), Version 1.5. April 2012. Environmental Fate 

and Effects Division, Office of Pesticide Programs, U.S. Environmental Protection Agency, 

Washington, D.C.

US EPA. 1996. Ecological Effects Test Guidelines, 850.2100 Avian Acute Oral Toxicity Test. 

Office of Chemical Safety and Pollution Prevention. EPA 712-C-96-139.

US EPA. 2002. Technical Basis for the Derivation of Equilibrium Partitioning Sediment 

Guidelines (ESGs) for the Protection of Benthic Organisms: Nonionic Organics. Office of 

Science and Technology and Office of Research and Development. Washington, DC 20460. 

EPA/822-R-02-041.

US EPA. 2004a. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs, U.S. Environmental Protection Agency: Endangered and Threatened Species Effects 

Determinations. Office of Prevention, Pesticide, and Toxic Substances.

USEPA. 2004b. Scientific Advisory Panel. March 30 - April 2, 2004: Refined (Level II) 

Terrestrial and Aquatic Models for Probabilistic and Ecological Assessment of Pesticides. 

Available: http://www.epa.gov/scipoly/sap/meetings/2004/033004_mtg.htm

US Office of the Federal Registrar. 2011. Code of Federal Regulations 40, Parts 150-189. 

Willis and McDowell, 1987. Pesticide persistence on foliage. Environ. Contam. Toxicol. 

100:23-73.
97

Appendix A. The Risk Quotient Method and Levels of Concern

The Risk Quotient Method is the means by which the Environmental Fate and Effects Division 

(EFED) integrates the results of exposure and ecotoxicity data. In this method, both acute and 

chronic risk quotients (RQs) are calculated by dividing exposure estimates by the most sensitive 

ecotoxicity values or toxicity endpoints derived from the studies. Calculated RQs are then 

compared to OPP's levels of concern (LOCs). The LOCs are the criteria used by OPP to indicate 

potential risk to non-target organisms and the need to consider regulatory action. EFED has 

defined LOCs for acute risk, potential restricted use, and for endangered species. Risk 

presumptions, along with the corresponding RQs and LOCs are summarized in the table below.

These LOCs are criteria used by EFED to indicate potential risk to non-target 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 non-target organisms. LOCs currently address the 

following risk presumption categories: (1) acute – potential for acute risk is high, regulatory

action may be warranted in addition to restricted use classification (2) acute restricted use -

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, regulatory

action may be warranted, and (4) chronic risk - the potential for chronic risk high, regulatory

action may be warranted. Currently, EFED does not perform assessment for chronic risk to 

plants, acute or chronic risks to non-target insects or chronic risks from granular/bait 

formulations to mammalian or avian species.

The ecotoxicity 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 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). An example of a toxicity test effect level derived from the results of 

a long-term laboratory study that assesses chronic effects is (1) NOAEC (birds, fish, and aquatic 

invertebrates). 

Risk Presumption RQ LOC

Birds

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 

mg/kg)

0.2

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Mammals

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 

mg/kg)

0.2
98

Risk Presumption RQ LOC

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Aquatic Animals

Acute Risk EEC/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC/EC25 1

Acute Endangered Species EEC/EC05 or NOAEC 1

Aquatic Plants

Acute Risk EEC/EC50 1

Acute Endangered Species EEC/EC05 or NOAEC 1
99

Appendix Appendix B. Output of STIR Results

Welcome to the EFED 

Screening Tool for Inhalation Risk

This tool is designed to provide the risk assessor with a rapid method for 

determining the potential

significance of the inhalation exposure route to birds and mammals in a risk 

assessment.

Input

Application and Chemical Information

Enter Chemical Name

Fenpyrazam

ine

Enter Chemical Use

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 331.4

Enter Chemical Vapor Pressure (mmHg) 2.17E-10

Enter Application Rate (lb a.i./acre) 1.07

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2000

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 2000

Enter Lowest Rat Inhalation LC50 (mg/L) 0.61

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 3.87E-06

Maximum 1-hour Vapor Inhalation Dose 

(mg/kg) 4.86E-07

Adjusted Inhalation LD50 3.40E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.43E-07 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 1.03E-01
100

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 3.02E-02 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 3.87E-06

Maximum 1-hour Vapor Inhalation Dose 

(mg/kg) 6.12E-07

Adjusted Inhalation LD50 3.63E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.68E-08 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 1.29E-01

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 3.56E-03 Exposure not Likely Significant
101

Appendix Appendix C. Output of SIP Results

Table 1. Inputs

Parameter Value

Chemical name Fenpyrazamine

Solubility (in water at 25oC; mg/L) 20.4

Mammalian LD50 (mg/kg-bw) 2000

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 3000

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Avian LD50 (mg/kg-bw) 2000

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 517

Bobwhite quail NOAEC (mg/kg-diet) 248

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird 

species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 3.5088 3.5088

Adjusted toxicity value (mg/kg-bw) 1538.3211 2307.4817

Ratio of exposure to toxicity 0.0023 0.0015

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 16.5240 16.5240

Adjusted toxicity value (mg/kg-bw) 1440.8590 25.6497

Ratio of exposure to acute toxicity 0.0115 0.6442
102

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. 

Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through 

drinking water may contribute to a total exposure that has potential for effects to non-target animals.
103

Appendix Appendix D. Output of TerrPlant Results

TerrPlant v. 1.2.2

Table 1. Chemical Identity.

Chemical Name Fenpyrazamine

PC code 90109

Use Almonds, pistachios

Application Method Aerial

Application Form Suspension concentrate 

Solubility in Water 

(ppm) 20.4

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol Value Units

Application Rate A 0.37

Incorporation I 1 none

Runoff Fraction R 0.02 none

Drift Fraction D 0.05 none

Table 3. EECs for Fenpyrazamine. Units in .

Description Equation EEC

Runoff to dry areas (A/I)*R 0.0074

Runoff to semi-aquatic areas (A/I)*R*10 0.074

Spray drift A*D 0.0185

Total for dry areas ((A/I)*R)+(A*D) 0.0259

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.0925

Table 4. Plant survival and growth data used for RQ derivation. Units are in .

Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 1.54 0.15 x 0.56

Dicot 0.53 0.035 x 0.56

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Fenpyrazamine through 

runoff and/or spray drift.*

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed <0.1 <0.1 <0.1

Monocot listed 0.17 0.62 0.12

Dicot non-listed <0.1 0.17 <0.1

Dicot listed 0.74 2.64 0.53

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
104

Table 1. Chemical Identity.

Chemical Name Fenpyrazamine

PC code 90109

Use Almonds, pistachios

Application Method Aerial

Application Form Suspension concentrate 

Solubility in Water 

(ppm) 204

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol Value Units

Application Rate A 0.49

Incorporation I 1 none

Runoff Fraction R 0.02 none

Drift Fraction D 0.05 none

Table 3. EECs for Fenpyrazamine. Units in .

Description Equation EEC

Runoff to dry areas (A/I)*R 0.0098

Runoff to semi-aquatic areas (A/I)*R*10 0.098

Spray drift A*D 0.0245

Total for dry areas ((A/I)*R)+(A*D) 0.0343

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.1225

Table 4. Plant survival and growth data used for RQ derivation. Units are in .

Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 1.54 0.15 x 0.56

Dicot 0.53 0.035 x 0.56

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Fenpyrazamine through 

runoff and/or spray drift.*

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed <0.1 <0.1 <0.1

Monocot listed 0.23 0.82 0.16

Dicot non-listed <0.1 0.23 <0.1

Dicot listed 0.98 3.50 0.70

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
105

Table 1. Chemical Identity.

Chemical Name Fenpyrazamine

PC code 90109

Use Almonds, pistachios

Application Method Aerial

Application Form Suspension concentrate 

Solubility in Water 

(ppm) 204

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol Value Units

Application Rate A 1.07

Incorporation I 1 none

Runoff Fraction R 0.02 none

Drift Fraction D 0.05 none

Table 3. EECs for Fenpyrazamine. Units in .

Description Equation EEC

Runoff to dry areas (A/I)*R 0.0214

Runoff to semi-aquatic areas (A/I)*R*10 0.214

Spray drift A*D 0.0535

Total for dry areas ((A/I)*R)+(A*D) 0.0749

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.2675

Table 4. Plant survival and growth data used for RQ derivation. Units are in .

Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 1.54 0.15 x 0.56

Dicot 0.53 0.035 x 0.56

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Fenpyrazamine through 

runoff and/or spray drift.*

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed <0.1 0.17 <0.1

Monocot listed 0.50 1.78 0.36

Dicot non-listed 0.14 0.50 0.10

Dicot listed 2.14 7.64 1.53

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
106

Appendix Appendix E. Sample PRZM/EXAMS Input and Output Files

Figure E-1. PE5 water column run for aerial application, NJ Nursery scenario.

stored as Aerial_NJNU.out

Chemical: Fenpyrazamine

PRZM environment: NJnurserySTD.txt modified Tueday, 26 August 2008 at 

06:16:42

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 

06:14:08

Metfile: w93730.dvf modified Tueday, 26 August 2008 at 06:16:14

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 20.84 20.62 20.06 18.76 17.88 6.544

1962 56.86 56.25 54.06 51.07 48.62 23.86

1963 40.79 40.42 39.11 37.47 36.37 31.54

1964 36.26 35.91 34.99 33.85 32.95 25.08

1965 30.86 30.57 29.95 28.98 27.85 22.02

1966 102 101 96.8 91.72 87.17 40.35

1967 92.14 91.32 88.16 83.14 80.2 59.62

1968 59.26 59.17 58.81 57.96 56.7 47.13

1969 36.97 36.92 36.67 35.66 34.41 29.07

1970 36.45 36.08 35.69 34.35 33.08 24.22

1971 89.46 88.64 85.88 82.33 79.12 40.89

1972 61.57 61.21 59.72 56.55 54.32 44.22

1973 40.31 39.92 38.37 35.55 34.28 28.23

1974 43.58 43.14 42.01 40.74 39.57 26.56

1975 45.24 44.96 43.49 41.27 40.14 28.55

1976 68.94 68.19 66.31 62.56 59.64 36.79

1977 59.52 58.91 56.89 53.98 51.87 40.57

1978 39.92 39.53 39.05 38.45 37.57 32.76

1979 34.32 34.07 33.39 32.35 31.51 24.59

1980 34.78 34.45 33.86 33.03 32.02 23.58

1981 31.05 30.84 30.16 29.18 28.23 22.9

1982 28.11 27.84 27.2 26.54 25.59 19.64

1983 33.4 33.04 32.38 31.07 29.85 19.83

1984 28.47 28.2 27.89 26.95 26.05 20.29

1985 32.04 31.82 30.6 29.64 28.49 19.62

1986 34.1 33.74 32.33 30.67 29.57 20.07

1987 31.98 31.68 31.18 30.14 29.18 22

1988 33.29 32.96 31.69 29.7 28.76 20.9

1989 58.56 58.01 57.33 53.82 52.81 29.57

1990 47.16 46.86 45.06 41.98 40.16 34.26
107

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.032258 102 101 96.8 91.72 87.17 59.62

0.064516 92.14 91.32 88.16 83.14 80.2 47.13

0.096774 89.46 88.64 85.88 82.33 79.12 44.22

0.129032 68.94 68.19 66.31 62.56 59.64 40.89

0.16129 61.57 61.21 59.72 57.96 56.7 40.57

0.193548 59.52 59.17 58.81 56.55 54.32 40.35

0.225806 59.26 58.91 57.33 53.98 52.81 36.79

0.258065 58.56 58.01 56.89 53.82 51.87 34.26

0.290323 56.86 56.25 54.06 51.07 48.62 32.76

0.322581 47.16 46.86 45.06 41.98 40.16 31.54

0.354839 45.24 44.96 43.49 41.27 40.14 29.57

0.387097 43.58 43.14 42.01 40.74 39.57 29.07

0.419355 40.79 40.42 39.11 38.45 37.57 28.55

0.451613 40.31 39.92 39.05 37.47 36.37 28.23

0.483871 39.92 39.53 38.37 35.66 34.41 26.56

0.516129 36.97 36.92 36.67 35.55 34.28 25.08

0.548387 36.45 36.08 35.69 34.35 33.08 24.59

0.580645 36.26 35.91 34.99 33.85 32.95 24.22

0.612903 34.78 34.45 33.86 33.03 32.02 23.86

0.645161 34.32 34.07 33.39 32.35 31.51 23.58

0.677419 34.1 33.74 32.38 31.07 29.85 22.9

0.709677 33.4 33.04 32.33 30.67 29.57 22.02

0.741935 33.29 32.96 31.69 30.14 29.18 22

0.774194 32.04 31.82 31.18 29.7 28.76 20.9

0.806452 31.98 31.68 30.6 29.64 28.49 20.29

0.83871 31.05 30.84 30.16 29.18 28.23 20.07

0.870968 30.86 30.57 29.95 28.98 27.85 19.83

0.903226 28.47 28.2 27.89 26.95 26.05 19.64

0.935484 28.11 27.84 27.2 26.54 25.59 19.62

0.967742 20.84 20.62 20.06 18.76 17.88 6.544

0.1 87.408 86.595 83.923 80.353 77.172 43.887

Average of yearly averages: 28.8418
108

Figure E-2. PE5 benthic pore water run for aerial application, NJ Nursery scenario.

stored as Aerial_NJNUben.out

Chemical: Fenpyrazamine

PRZM environment: NJnurserySTD.txt modified Tueday, 26 August 2008 at 

06:16:42

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 

06:14:08

Metfile: w93730.dvf modified Tueday, 26 August 2008 at 06:16:14

Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 10.79 10.79 10.69 10.18 9.461 2.885

1962 28.57 28.56 28.49 27.63 26.34 13.49

1963 28.56 28.54 28.48 28.25 27.84 20.72

1964 21.77 21.77 21.74 21.44 20.94 16.3

1965 19.54 19.52 19.45 19.21 18.87 14.58

1966 49.55 49.55 49.42 48.22 46.12 22.41

1967 49.54 49.51 49.26 48.22 47.33 39.86

1968 47.26 47.18 46.85 46.12 45.37 32.24

1969 28.95 28.92 28.78 28.38 27.88 19.71

1970 19.79 19.79 19.75 19.55 19.23 15.51

1971 46.32 46.32 46.23 44.76 42.65 23.26

1972 46.31 46.31 46.22 45.4 44.41 30.94

1973 26.82 26.81 26.68 26.08 25.26 18.55

1974 23.24 23.24 23.21 22.76 21.93 16.78

1975 24.39 24.38 24.29 23.66 22.81 18.32

1976 35.31 35.31 35.25 34.63 33.43 23.04

1977 35.32 35.32 35.29 35.01 34.26 26.21

1978 30.1 30.09 30.04 29.84 29.57 22.15

1979 21.68 21.66 21.53 21.06 20.58 16.09

1980 19.76 19.76 19.66 19.17 18.36 15.18

1981 19.83 19.83 19.83 19.73 19.47 15.05

1982 16.8 16.79 16.74 16.54 16.19 12.69

1983 17.47 17.47 17.43 16.98 16.32 12.3

1984 17.47 17.46 17.42 17.21 16.92 13.03

1985 16.01 16 15.91 15.52 15.12 12.15

1986 17.47 17.47 17.42 16.9 16.19 12.67

1987 17.47 17.47 17.43 17.3 17.09 14.06

1988 17.28 17.26 17.19 16.97 16.61 13.52

1989 32.52 32.49 32.16 30.96 29.39 17.37

1990 32.65 32.65 32.62 32.13 31.33 22.9
109

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.032258 49.55 49.55 49.42 48.22 47.33 39.86

0.064516 49.54 49.51 49.26 48.22 46.12 32.24

0.096774 47.26 47.18 46.85 46.12 45.37 30.94

0.129032 46.32 46.32 46.23 45.4 44.41 26.21

0.16129 46.31 46.31 46.22 44.76 42.65 23.26

0.193548 35.32 35.32 35.29 35.01 34.26 23.04

0.225806 35.31 35.31 35.25 34.63 33.43 22.9

0.258065 32.65 32.65 32.62 32.13 31.33 22.41

0.290323 32.52 32.49 32.16 30.96 29.57 22.15

0.322581 30.1 30.09 30.04 29.84 29.39 20.72

0.354839 28.95 28.92 28.78 28.38 27.88 19.71

0.387097 28.57 28.56 28.49 28.25 27.84 18.55

0.419355 28.56 28.54 28.48 27.63 26.34 18.32

0.451613 26.82 26.81 26.68 26.08 25.26 17.37

0.483871 24.39 24.38 24.29 23.66 22.81 16.78

0.516129 23.24 23.24 23.21 22.76 21.93 16.3

0.548387 21.77 21.77 21.74 21.44 20.94 16.09

0.580645 21.68 21.66 21.53 21.06 20.58 15.51

0.612903 19.83 19.83 19.83 19.73 19.47 15.18

0.645161 19.79 19.79 19.75 19.55 19.23 15.05

0.677419 19.76 19.76 19.66 19.21 18.87 14.58

0.709677 19.54 19.52 19.45 19.17 18.36 14.06

0.741935 17.47 17.47 17.43 17.3 17.09 13.52

0.774194 17.47 17.47 17.43 17.21 16.92 13.49

0.806452 17.47 17.47 17.42 16.98 16.61 13.03

0.83871 17.47 17.46 17.42 16.97 16.32 12.69

0.870968 17.28 17.26 17.19 16.9 16.19 12.67

0.903226 16.8 16.79 16.74 16.54 16.19 12.3

0.935484 16.01 16 15.91 15.52 15.12 12.15

0.967742 10.79 10.79 10.69 10.18 9.461 2.885

0.1 47.166 47.094 46.788 46.048 45.274 30.467

Average of yearly averages: 18.4655

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: Aerial_NJNU

Metfile: w93730.dvf

PRZM scenario: NJnurserySTD.txt

EXAMS environment file: pond298.exv
110

Chemical Name: Fenpyrazamine

Description Variable Name Value Units Comments

Molecular weight mwt 331.4 g/mol

Henry's Law Const. henry 2.28e-10 atm-m^3/mol

Vapor Pressure vapr 2.17e-10 torr

Solubility sol 20.4 mg/L

Kd Kd 5.06 mg/L

Koc Koc mg/L

Photolysis half-life kdp 1.64 days Half-life

Aerobic Aquatic Metabolism kbacw 551 days Halfife

Anaerobic Aquatic Metabolism kbacs 36.6 days Halfife

Aerobic Soil Metabolism asm 478.09 days Halfife

Hydrolysis: pH 4 0 days Half-life

Hydrolysis: pH 7 0 days Half-life

Hydrolysis: pH 9 0 days Half-life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI cm

Application Rate:TAPP 1.22 kg/ha

Application Efficiency: APPEFF 0.95 fraction

Spray Drift DRFT 0.05 fraction of application rate applied to pond

Application Date Date 01-08 dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 1 interval 7 days Set to 0 or delete line for single app.

app. rate 1 apprate 1.22 kg/ha

Interval 2 interval 7 days Set to 0 or delete line for single app.

app. rate 2 apprate 1.22 kg/ha

Record 17: FILTRA

IPSCND 3

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

Flag for runoff calc. RUNOFF none none, monthly or total(average of 

entire run)
111

Figure E-3. EXAMS sediment concentration output file for aerial application, NJ Nursery 

scenario.

 BENTHIC SEDIMENT CONCENTRATION (mg/kg) 

 YEAR PEAK 24HOUR 96HOUR 21 DAY 60 DAY 90 DAY ANNUAL

 ---- ------ ------ ------ ------ ------ ------ ------

 1961 0.059 0.059 0.059 0.058 0.055 0.051 0.016

 1962 0.155 0.155 0.155 0.155 0.150 0.143 0.073

 1963 0.155 0.155 0.155 0.155 0.153 0.151 0.113

 1964 0.118 0.118 0.118 0.118 0.116 0.114 0.089

 1965 0.106 0.106 0.106 0.106 0.104 0.102 0.079

 1966 0.269 0.269 0.269 0.268 0.262 0.250 0.122

 1967 0.269 0.269 0.269 0.268 0.262 0.257 0.216

 1968 0.257 0.257 0.256 0.254 0.250 0.246 0.175

 1969 0.157 0.157 0.157 0.156 0.154 0.151 0.107

 1970 0.107 0.107 0.107 0.107 0.106 0.104 0.084

 1971 0.252 0.252 0.252 0.251 0.243 0.232 0.126

 1972 0.251 0.251 0.251 0.251 0.246 0.241 0.168

 1973 0.146 0.146 0.146 0.145 0.142 0.137 0.101

 1974 0.126 0.126 0.126 0.126 0.124 0.119 0.091

 1975 0.132 0.132 0.132 0.132 0.128 0.124 0.099

 1976 0.192 0.192 0.192 0.191 0.188 0.182 0.125

 1977 0.192 0.192 0.192 0.192 0.190 0.186 0.142

 1978 0.163 0.163 0.163 0.163 0.162 0.161 0.120

 1979 0.118 0.118 0.118 0.117 0.114 0.112 0.087

 1980 0.107 0.107 0.107 0.107 0.104 0.100 0.082

 1981 0.108 0.108 0.108 0.108 0.107 0.106 0.082

 1982 0.091 0.091 0.091 0.091 0.090 0.088 0.069

 1983 0.095 0.095 0.095 0.095 0.092 0.089 0.067

 1984 0.095 0.095 0.095 0.095 0.093 0.092 0.071

 1985 0.087 0.087 0.087 0.086 0.084 0.082 0.066

 1986 0.095 0.095 0.095 0.095 0.092 0.088 0.069

 1987 0.095 0.095 0.095 0.095 0.094 0.093 0.076

 1988 0.094 0.094 0.094 0.093 0.092 0.090 0.073

 1989 0.177 0.177 0.176 0.175 0.168 0.160 0.094

 1990 0.177 0.177 0.177 0.177 0.174 0.170 0.124

 SORTED FOR PLOTTING 

------ --- --------

 PROB PEAK 24HOUR 96HOUR 21 DAY 60 DAY 90 DAY ANNUAL

 ----- ------ ------ ------ ------ ------ ------ ------

 0.032 0.269 0.269 0.269 0.268 0.262 0.257 0.216

 0.065 0.269 0.269 0.269 0.268 0.262 0.250 0.175

 0.097 0.257 0.257 0.256 0.254 0.250 0.246 0.168

 0.129 0.252 0.252 0.252 0.251 0.246 0.241 0.142

 0.161 0.251 0.251 0.251 0.251 0.243 0.232 0.126

 0.194 0.192 0.192 0.192 0.192 0.190 0.186 0.125

 0.226 0.192 0.192 0.192 0.191 0.188 0.182 0.124

 0.258 0.177 0.177 0.177 0.177 0.174 0.170 0.122
112

 0.290 0.177 0.177 0.176 0.175 0.168 0.161 0.120

 0.323 0.163 0.163 0.163 0.163 0.162 0.160 0.113

 0.355 0.157 0.157 0.157 0.156 0.154 0.151 0.107

 0.387 0.155 0.155 0.155 0.155 0.153 0.151 0.101

 0.419 0.155 0.155 0.155 0.155 0.150 0.143 0.099

 0.452 0.146 0.146 0.146 0.145 0.142 0.137 0.094

 0.484 0.132 0.132 0.132 0.132 0.128 0.124 0.091

 0.516 0.126 0.126 0.126 0.126 0.124 0.119 0.089

 0.548 0.118 0.118 0.118 0.118 0.116 0.114 0.087

 0.581 0.118 0.118 0.118 0.117 0.114 0.112 0.084

 0.613 0.108 0.108 0.108 0.108 0.107 0.106 0.082

 0.645 0.107 0.107 0.107 0.107 0.106 0.104 0.082

 0.677 0.107 0.107 0.107 0.107 0.104 0.102 0.079

 0.710 0.106 0.106 0.106 0.106 0.104 0.100 0.076

 0.742 0.095 0.095 0.095 0.095 0.094 0.093 0.073

 0.774 0.095 0.095 0.095 0.095 0.093 0.092 0.073

 0.806 0.095 0.095 0.095 0.095 0.092 0.090 0.071

 0.839 0.095 0.095 0.095 0.095 0.092 0.089 0.069

 0.871 0.094 0.094 0.094 0.093 0.092 0.088 0.069

 0.903 0.091 0.091 0.091 0.091 0.090 0.088 0.067

 0.935 0.087 0.087 0.087 0.086 0.084 0.082 0.066

 0.968 0.059 0.059 0.059 0.058 0.055 0.051 0.016

 1/10 0.257 0.257 0.256 0.254 0.250 0.245 0.165
113

Appendix F. Formation of Fenpyrazamine Transformation Products in 

Environmental Fate Studies

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

Hydrolysis (MRID No. 48399923)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

NA

Metabolite 

detected at pH4, 

pH 7, and pH 9.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

NA

Metabolite 

detected at pH 7 

and pH 9.

Aqueous Photolysis (MRID No. 48399924)

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

65.6 % at 7 

days

Study terminated 

at 30 days.

MCNI

2-Cyano-N-isopropyl-2-(otolyl)acetamide

19.9% at 30 

days

Study terminated 

at 30 days.

S-2188-DTC

1-Allyl-5-amino-2-isopropyl-4-(otolyl)pyrazol-3-one

6.3% at 30 

days

Study terminated 

at 30 days.
114

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

Soil Photolysis (MRID No. 48399926)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

1.6 % at 30 

days

Study terminated 

at 30 days.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

0.4 % at 21 

days

Study terminated 

at 30 days.

Aerobic Soil Metabolism (MRID Nos. 48399920 and 48399927)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

9.1 % at 181 

days

Detected in NJ 

Silt Loam Soil 

(MRID No. 

48399927).

Study terminated 

at 370 days.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

2.8 % at 14 

days

Detected in UK 

Silt Loam Soil 

(MRID No. 

48399920).

Study terminated 

at 120 days.
115

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

MPPZ

5-Amino-4-(o-tolyl)-1,2-

dihydropyrazol-3-one

0.2 % at 120 

days

Detected in NJ 

Silt Loam Soil 

(MRID No. 

48399927).

Study terminated 

at 370 days.

Anaerobic Soil Metabolism (MRID No. 48399928)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

22.9 % at 252 

days

Detected in NJ 

Silt Loam Soil 

(MRID No. 

48399928).

Study terminated 

at 364 days.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

22 % at 364 

days

Detected in NJ 

Silt Loam Soil 

(MRID No. 

48399928).

Study terminated 

at 364 days.
116

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

MPPZ

5-Amino-4-(o-tolyl)-1,2-

dihydropyrazol-3-one

0.4 % at 16 

days

Detected in NJ 

Silt Loam Soil 

(MRID No. 

48399928).

Study terminated 

at 364 days.

Aerobic Aquatic Metabolism (MRID No. 48399929)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

17.3 % at 30 

days

Detected in 

Calwich Lake 

Water – Silty Clay 

Loam Seiment 

(MRID No. 

48399929).

Study terminated 

at 100 days.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

23.5 % at 7 

days

Detected in 

Calwich Lake 

Water – Silty Clay 

Loam Seiment 

(MRID No. 

48399929).

Study terminated 

at 100 days.

MCNI

2-Cyano-N-isopropyl-2-(otolyl)acetamide

0.8% at 61 

days

Detected in 

Calwich Lake 

Water – Silty Clay 

Loam Seiment 

(MRID No. 

48399929).

Study terminated 

at 100 days.
117

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

Anaerobic Aquatic Metabolism (MRID No. 48399930)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

5.6% at 63 

days

Detected in MS 

Creek Water –

Clay Sediment 

(MRID No. 

48399930).

Study terminated 

at 364 days.

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

90.3 % at 63 

and 120 days

Detected in MS 

Creek Water –

Clay Sediment 

(MRID No. 

48399930).

Study terminated 

at 364 days.

Terrestrial Field Dissipation (MRID Nos. 48399931, 48399932, 48399933, and 48399934)

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

17.0 % at 0 

Days

Detected in ID 

Loam Soil (MRID 

No. 48399933).

Study terminated 

at 240 days.

Fish BCF (MRID No. 48400005)

S-2188-OH

5-Amino-4-hydroxy-2-isopropyl4-(o-tolyl)pyrazol-3-one

2.7 % at 3 

Days

Detected during 

depuration phase 

at low dose 

concentration in 

edible fish tissue.

Percentage 

represents portion 

of total radioactive 

residue recovered.

Study terminated 

at 14 days of 

depuration.
118

Degradate

Identity Structure

Max% of 

Applied 

and Days 

Post 

Application

Comments

S-2188-DC

5-Amino-2-isopropyl-4-(o-tolyl)-

1H-pyrazol-3-one

16.2 % at 0 

Days

Detected during 

depuration phase 

at low dose 

concentration in 

edible fish tissue.

Percentage 

represents portion 

of total radioactive 

residue recovered.

Study terminated 

at 14 days of 

depuration.

S-2188-DC Conjugate

5-Amino-4-[2-

(hydroxymethyl)phenyl]-2-

isopropyl-1H-pyrazol-3-one

42.0 % at 3 

Days

Detected during 

depuration phase 

at low dose 

concentration in 

edible fish tissue.

Percentage 

represents portion 

of total radioactive 

residue recovered.

Study terminated 

at 14 days of 

depuration.
119

Appendix G. Toxicity Comparisons of Fenpyrazamine and Transformation 

Products

The most sensitive toxicity endpoints for aquatic organisms are listed in Table G-1 for the parent 

compound and any transformation products for which data are available. For fenpyrazamine, 

there is toxicity information on three transformation products for acute exposure to daphnia 

magna (MCNI, S-2188_DC, and S-2188-OH) and for acute exposure to freshwater fish and 

freshwater green algae there is toxicity information for two transformation products (S-2188-DC 

and S-2188-OH). From Table G-1 below, it is noted that parent fenpyrazamine is more toxic on 

an acute exposure basis to freshwater fish, freshwater invertebrates and freshwater green algae. 

In all studies for freshwater invertebrates and fish for all transformation products, the degradate 

was not toxic up to the highest concentration tested and therefore was at least one order of 

magnitude less sensitive than parent fenpyrazamine. Although definitive EC50 values were 

achieved for the transformation products exposed to freshwater green algae, the data show that 

parent fenpyrazamine is more toxic to freshwater green algae by at least one order of magnitude. 

Therefore, available data on three transformation products to fenpyrazamine exposed to three 

aquatic taxa show that parent fenpyrazamine is more toxic than its major degradates.

Toxic effects resulting from exposure to chemicals with a similar mode of action are usually a 

function of the number of molecules and thus it is appropriate to compare toxicity on the basis of 

molar mass, especially when molecular weight differs substantially (e.g., several fold) between 

the two compounds (Rand, 2003). Expressing the endpoints on a parent equivalents basis is 

essentially equivalent to the expression of the endpoint on a molar basis, it is simply normalized 

to the parent compound’s molecular weight rather than to moles. Table G-1 shows the results of 

this analysis and it is noted that the degradates, when expressed on a parent equivalent basis, 

show to be less toxic than parent fenpyrazamine. 

Table G-1. Toxicity Comparison of Parent Compound and Transformation Products.A

Test Material

MW

(g/mol) Test Species Endpoint

Toxicity Value 

in mg/L (95% 

Confidence 

Interval)

Degradate Toxicity 

Expressed in Parent 

Compound 

Equivalents in mg/L 

(95% Confidence 

Interval) B

Freshwater Fish

Fenpyrazamine 331.4 

g/mol Rainbow Trout (O. mykiss)

96-hr LC50

5.2 (3.8 – 7.8) 5.2 (3.8 – 7.8)

S-2188-OH 247.3 

g/mol Rainbow Trout (O. mykiss) >97 >130

S-2188-DC 231.3 

g/mol Rainbow Trout (O. mykiss) >89 >128

Freshwater Invertebrates

Fenpyrazamine 331.4 

g/mol Water flea (Daphnia magna)

48-hr EC50

5.5 (4.6 – 6.5) 5.5 (4.6 – 6.5)

MCNI 216.3 

g/mol Water flea (Daphnia magna) >50 >76.6

S-2188-OH 247.3 

g/mol Water flea (Daphnia magna) >98 >131
120

Test Material

MW

(g/mol) Test Species Endpoint

Toxicity Value 

in mg/L (95% 

Confidence 

Interval)

Degradate Toxicity 

Expressed in Parent 

Compound 

Equivalents in mg/L 

(95% Confidence 

Interval) B

S-2188-DC 231.3 

g/mol Water flea (Daphnia magna) >94 >135

Aquatic PlantsC

Fenpyrazamine 331.4 

g/mol Green alga (P. subcapitata)

96-hr EC50

0.16 (0.12 –

0.22) 0.16 (0.12 – 0.22)

S-2188-OH 247.3 

g/mol Green alga (P. subcapitata) 49 (41 – 58) 65.7 (54.9 – 77.7)

S-2188-DC 231.3 

g/mol Green alga (P. subcapitata) 32 (30 – 35) 45.8 (43 – 50.1)

A Bold values indicate degradate toxicity that is potentially equivalent to the parent compound (i.e., the toxicity of 

the parent compound and the degradate are within an order of magnitude or the confidence intervals overlap or 

both). 

B Degradate toxicity in parent compound equivalents (mg/L) = (MW parent/MW degradate) x (toxicity endpoint of 

degradate (mg/L)).

C The most sensitive endpoint for all green algae studies (parent fenpyrazamine and degradate) was cell density.

ECOSAR (v1.0) was used to estimate the toxicity of the transformation products listed in Table 

G-2 because study data were not available with which to evaluate their toxicity. ECOSAR 

predicts toxicity using a regression of the log KOW and measured toxicity endpoints for a 

particular species and chemical class. ECOSAR is only used to prioritize the need for additional 

data on transformation products. Data on the aliphatic amine, hydrazine, benzyl alcohol, amide, 

and benzyl nitrile chemical classes were used to estimate toxicity endpoints (see the description 

of data in the Help section of ECOSAR). Very limited data sets were available to develop the 

regressions for the compounds and there is large uncertainty in the estimated values. However, 

this is one of the best methods available to estimate ecological toxicity.

Table G-2 lists available data for fenpyrazamine and its major degradates alongside of those 

endpoints predicted by ECOSAR. For acute exposure, parent fenpyrazamine is generally more 

toxic by one to several orders of magnitude than ECOSAR predicted endpoints. In the cases 

where ECOSAR predicts a more sensitive value than what measured data in a study yielded, it is 

noted that the uncertainties and limitations associated with structure activity relationship 

analyses make these predicted endpoints less confident. This was particularly the case for the 

hydrazine ECOSAR class where the predicted endpoints would be lower than those results that 

were determined in a study. There was only one case where ECOSAR predicted an endpoint 

where the degradate toxicity was more sensitive than parent fenpyrazamine. This was the 

chronic value for fish for the MCNI (amide) degradate with a 0.13 mg/L. This value, despite 

being more toxic, is still within an order of magnitude for one of chronic NOAEC available for 

parent fenpyrazamine, 0.37 mg/L. The other chronic NOAEC value available for fenpyrazamine 

was determined to be lower than the lowest concentration tested (<0.039 mg/L). 
121

Table G-2. ECOSAR Estimates of Transformation Product Toxicity. A

Compound (Chemical 

Class) C

Estimated Toxicity Value (mg/L)

96-hr FW fish EC50

48-hr FW 

Daphnid LC50

Fish NOAEC Daphnid 

NOAEC

96-hr EC50

Green Algae

Fenpyrazamine B

(Pyrazole)

(5.2, 5.4) (5.5) (0.37, <0.039) (0.34) (0.16)

S-2188-OH

(Aliphatic amine)

(>97)

278.24

(>98)

30 25.71 2.15 (49)32.58

S-2188-OH

(Hydrazine)

(>97)

5.91

(>98)

7.74 0.44D

0.55D (49)

0.11

S-2188-OH

(Benzyl alcohol)

(>97)

845.21

(>98)

610.39 57.95D

75.18D (49)

168.50

S-2188-OH

(Amides)

(>97)

856.60

(>98)

297.16 4.00 62.24 (49)11.67

S-2188-DC

(Aliphatic amine)

(>89)

614.25

(>94)

62.98 70.85 4.23 (32)78.12

S-2188-DC

(Hydrazines)

(>89)

8.78

(>94)

10.12 0.78D

0.92D (32)

0.12

S-2188-DC

(Amides)

(>89)

2644.60E

(>94)

614.06 10.66 150.50 (32)20.44

MCNI

(Amides) 16.82 (>50)20.91 0.13 2.66 1.39

MCNI 

(Benzyl nitriles) 9.10 (>50)49.08 1.42 3.3 x 107 E

1.58

S-2188-DC conjugate 

S-2188-CH2OH-DC

(Aliphatic amines)

5773.72 520.75 1167.33 29.67 904.74

S-2188-DC conjugate 

S-2188-CH2OH-DC

(Hydrazines)

30.15 25.41 4.21D4.32D0.15

S-2188-DC conjugate 

S-2188-CH2OH-DC

(Benzyl alcohols)

53419E32828E2361.2D2411.9D4130.2

S-2188-DC conjugate 

S-2188-CH2OH-DC

(Amides)

58097E4882.8 161.32 1781.1 106.81

A Toxicity values in parentheses were measured. All other toxicity values were estimated with ECOSAR (v1.0). 

B Toxicity values for the parent compound were not estimated because the transformation products are in a different 

chemical class and are assumed to have a different mode of action.

C Chemical class used by ECOSAR to predict toxicity.

D ECOSAR reported this endpoint using acute to chronic ratios (ACRs)

E ECOSAR reported the chemical may not be soluble enough to measure this predicted endpoint

Rand, G. M. 2003. Aquatic Toxicology (Second ed.). London: Taylor & Francis.