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OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 000325

DP Barcodes: 357063

MEMORANDUM Date: January 28, 2010

SUBJECT: Metrafenone: Ecological Risk Assessment For Proposed Use on Grapes

FROM: Tanja Crk, M.A., Biologist

James A. Hetrick, Ph.D., Senior Scientist

Dana Spatz, Branch Chief

Environmental Risk Branch III

Environmental Fate and Effects Division (7507P)

Office of Pesticide Programs

TO: Mary Waller, Product Manager

Fungicide Branch

Registration Division (7505P) 

Office of Pesticide Programs

This memorandum transmits the Environmental Fate and Effects Division’s (EFED) 

environmental risk assessment for the active ingredient, metrafenone, as a fungicide for 

uses on grapes to treat powdery mildew; it is used for preventive but not curative 

measures. The proposed end-use product Metrafenone 300 is a suspension concentrate 

containing 25.2% metrafenone. Ground (liquid) application is the proposed method of 

application. The maximum single application rate is 0.300 lbs a.i./A; at 6 applications per 

season, the seasonal maximum rate is 1.80 lbs a.i./A. The minimum application interval is 

14 days.

While metrafenone is expected to be slightly mobile, its major routes of degradation are 

aqueous photolysis and aquatic metabolism, in both aerobic and anaerobic conditions. 

Soil metabolism is slow, with laboratory half-lives of 6 months to a year and 

accumulation over two years observed in field studies. In aquatic environments, the 
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measured photolysis half-life was 6.4 days and metabolism in both aerobic and anaerobic 

occurred with half-lives of one to four weeks. Exposure is expected to be dominated by

runoff and spray drift. Metrafenone exposure may also result from off-site movement in 

runoff water and on metrafenone -bearing soil particulates to adjacent fields (soil 

erosion). The moderate Koc’s (Koc 1073 to 22517 L/kg-oc) of metrafenone suggest that 

leaching to ground water/recharge to surface water would not be a route of exposure. 

Long-range transport of metrafenone in the gas phase is not considered a significant route 

of exposure. While the high log Kow (4.3 at 25oC, pH 4) would suggest the potential for 

bioaccumulation, the lipid normalized BCF (between 140 and 530) indicates that 

metrafenone is not expected to accumulate in tissues of aquatic organisms.

The results of this screening-level assessment indicate a potential for direct adverse 

effects to non-target mammals (dose-based RQs 1.14-2.91) following chronic exposure; 

these RQs also exceed the federally listed species LOC. Due to the potential for direct 

adverse effects to mammals associated with the application of metrafenone on grapes, 

indirect effects may consequently affect other aquatic and terrestrial species. To reduce 

chronic risk to mammals, several components of the application protocol would have to 

change. For example, in order to have no chronic LOC exceedances (i.e., all RQs < 1) for 

mammals, the minimum single application rate (0.2 lbs a.i./A) would have to be cut by 

25% (i.e., to 0.15 lbs a.i./A) yet considered the maximum instead, the application interval 

would have to nearly double (from 14 days up to 26 days), and the maximum allowed 

number of applications would have to be cut from 6 to 5. Alternatively, in order to have 

no chronic LOC exceedances for mammals, the minimum single application rate (0.2 lbs 

a.i./A) can still be applied yet considered the maximum instead, but the application 

interval would have to nearly double (from 14 days up to 26 days), and the maximum 

number of applications would have to be cut by 50% (i.e., from 6 to 3). Furthermore, in 

order to have no chronic LOC exceedances in nearly all cases for mammals –the one 

exception being an exceedance for the 15g size glass consuming short grass where the 

calculated RQ is 1.02 – the minimum single application rate (0.2 lbs a.i./A) would be 

changed to the maximum single application rate and the application interval (14 days) 

could remain as currently prescribed by the label, but the maximum number of 

applications would have to be reduced from 6 to 2.

Data were either not submitted or were deemed invalid for freshwater invertebrates and 

marine/estuarine fish via chronic exposure. Without data, risk cannot be ruled out for 

these taxa (either non-listed or federally listed species). 

Non-definitive endpoints – in this case, where total concentrations were estimated instead 

of the preferred dissolved concentrations in the majority of aquatic studies on 

metrafenone – suggest potential chronic risk to federally listed freshwater fish and acute 

risk to federally listed marine/estuarine invertebrates. More detailed risk conclusions are 

provided in the environmental risk assessment document.

Data Needs
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The ecotoxicity and environmental fate data needs are summarized in Tables 1 and 2 

below. Further explanation and characterization of these data needs can be found in the 

executive summary of the ecological risk assessment.

Table 1. Ecological Toxicity Data Gaps

Study Reason

850.1075 Acute toxicity freshwater fish Non-definitive endpoint w/effects 

observed

850.1400 Freshwater fish early-life stage (chronic) Non-definitive endpoint w/effects 

observed

850.1300 Aquatic freshwater invertebrate life-cycle (chronic) Invalid, CFR data gap

850.1025 Acute marine/estuarine invertebrate (oyster)

 Or

850.1035 Acute marine/estuarine invertebrate (mysid)

Non-definitive endpoint w/effects 

observed

OECD 218 Freshwater invertebrate whole sediment study 

(chronic)

Invalid, CFR data gap

850.4400 Aquatic vascular plant growth, Tier II Non-definitive endpoint w/effects 

observed

850.5400 Aquatic non-vascular plant growth, Tier II Non-definitive endpoint w/effects 

observed

850.2100 Avian acute oral toxicity test (passerine species) Not submitted, CFR data gap

850.3020 Honeybee acute contact toxicity (on TEP) Address formulation uncertainty

850.4100 Seedling Emergence, Tier II (on TEP) Address formulation uncertainty

850.4150 Vegetative Vigor, Tier II (on TEP) Address formulation uncertainty

Table 2. Environmental Fate Data Gaps

835.6100 Independent Laboratory Validations
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NEW CHEMICAL REGISTRATION

(Section 3)

 ECOLOGICAL RISK ASSESSMENT

Metrafenone: Fungicide

USEPA PC # 000325

Chemical Name(s): (3-bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-

methylphenyl)methanone (CAS)

3’-bromo-2,3,4,6’-tetramethoxy-2’,6-dimethylbenzophenone 

(IUPAC)

Chemical Abstracts Service (CAS) Number: 220899-03-6

Chemical Family: Benzophenone fungicide

Pesticidal Mode of Action: Inhibits growth of mycelium on the leaf surface, leaf 

penetration, formation of haustoria, and sporulation. Likely 

affects actin proteins which play a role in cell function and 

cell division.

Proposed End-use Product: Metrafenone 300 SC (EPA Reg.No.7969-xxx);

 Suspension Concentrate, 25.2% (2.5 lbs a.i./gallon)

Target Pest(s): Powdery mildew produced by Uncinula necator

Proposed Target Crop(s): Grapes

Risk Assessors: Tanja Crk, MA, Biologist

James A. Hetrick, PhD, Senior Scientist

Environmental Risk Branch III

Environmental Fate and Effects Division

Secondary Reviewers:Pamela Hurley, PhD, Toxicologist

Environmental Risk Branch III

Environmental Fate and Effects Division

Through: Dana Spatz, Branch Chief 

Environmental Risk Branch III

Environmental Fate and Effects Division
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Table of Contents

I. EXECUTIVE SUMMARY ...................................................................................... 5 

A. Nature of the Chemical Stressor ............................................................................. 5 

B. Potential Risks to Non-target Organisms................................................................ 5 

C. Environmental Fate Summary ................................................................................ 6 

D. Ecological Effects Summary................................................................................... 7 

E. Uncertainties and Data Gaps................................................................................... 8 

1. Environmental Fate and Exposure...................................................................... 8 

2. Ecological Effects Data....................................................................................... 9 

F. Endangered Species Considerations.................................................................... 12

II. PROBLEM FORMULATION .......................................................................... 13

A. Nature of Regulatory Action................................................................................. 13

B. Stressor Source and Distribution .......................................................................... 13

1. Nature of the Chemical Stressor ................................................................... 13 

a. Mode of Action (MoA) of Metrafenone ...................................................... 15

b. Reactions of Metrafenone in the Environment ...... 15 Error! Bookmark not 

defined.Error! Bookmark not defined.

2. Overview of Pesticide Usage ........................................................................... 15 

C. Receptors............................................................................................................... 15 

1. Aquatic and Terrestrial Effects......................................................................... 15 

2. Ecosystems Potentially at Risk ......................................................................... 17

D. Assessment Endpoints .......................................................................................... 17 

E. Conceptual Model................................................................................................. 17 

1. Risk Hypothesis................................................................................................ 17 

2. Conceptual Diagram ......................................................................................... 18

F. Analysis Plan ....................................................................................................... 19 

1. Conclusions from Previous Risk Assessments................................................. 19 

2. Preliminary Identification of Data Gaps........................................................... 19 

3. Measures of Exposure and Effects.................................................................... 23

a. Aquatic Exposure Models............................................................................. 24

b. Terrestrial Exposure Models......................................................................... 24

III. ANALYSIS .......................................................................................................... 28

A. Use Characterization............................................................................................. 28

B. Exposure Characterization.................................................................................... 28

1. Environmental Fate and Transport.................................................................... 28

2. Measures of Aquatic Exposure ......................................................................... 31

a. Aquatic Exposure Modeling ......................................................................... 31

b. Aquatic Exposure Monitoring and Field Data .............................................. 37

c. Aquatic Bioaccumulation Assessment.......................................................... 37

3. Measures of Terrestrial Exposure ..................................................................... 36

a. Terrestrial Exposure Modeling ..................................................................... 36

C. Ecological Effects Characterization...................................................................... 38 

1. Aquatic Effects Characterization ...................................................................... 38 
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a. Aquatic Animals ........................................................................................... 38 

(1) Acute Effects........................................................................................ 38 

(2) Chronic Effects ..................................................................................... 47 

b. Aquatic Plants............................................................................................... 49 

2. Terrestrial Effects Characterization .................................................................. 55 

a. Terrestrial Animals ....................................................................................... 55 

(1) Acute Effects......................................................................................... 55 

(2) Chronic Effects ..................................................................................... 62 

b. Terrestrial Plants........................................................................................... 67 

IV. RISK CHARACTERIZATION......................................................................... 68 

A. Risk Estimation - Integration of Exposure and Effects Data............................... 68 

1. Risk to Aquatic Animals and Plants................................................................. 68 

a. Aquatic Animals ........................................................................................... 68 

(1) Risk Following Acute Exposure ........................................................... 68 

(2) Risk Following Chronic Exposure........................................................ 69 

b. Aquatic Plants............................................................................................... 70 

2. Risk to Terrestrial Animals and Plants ............................................................. 70 

a. Terrestrial Animals ....................................................................................... 70 

(1) Risk Following Acute Exposure ........................................................... 71 

(2) Risk Following Chronic Exposure........................................................ 72 

b. Terrestrial Plants........................................................................................... 75 

B. Risk Description.................................................................................................... 75

1. Risk to Aquatic Animals and Plants................................................................. 75 

a. Aquatic Animals ........................................................................................... 75 

(1) Risk Following Acute Exposure ........................................................... 75 

(2) Risk Following Chronic Exposure........................................................ 78 

b. Aquatic Plants............................................................................................... 79 

2. Risk to Terrestrial Animals and Plants ............................................................. 80 

a. Terrestrial Animals ....................................................................................... 80 

(1) Risk Following Acute Exposure ........................................................... 80 

(2) Risk Following Chronic Exposure........................................................ 82 

b. Terrestrial Plants........................................................................................... 83 

3. Review of Incident Data ................................................................................... 84 

4. Endocrine Effects.............................................................................................. 84 

5. Federally Threatened and Endangered (Listed) Species................................... 85 

a. Action Area................................................................................................... 86 

b. Taxonomic Groups Potentially at Risk......................................................... 86 

(1) Discussion of Risk Quotients................................................................ 89

(2) Probit Dose Response Relationship...................................................... 89 

(3) Data Related to Under-represented Taxa.............................................. 90 

(4) Implications of Sublethal Effects.......................................................... 90 

c. Indirect Effects Analysis............................................................................... 92 

d. Critical Habitat.............................................................................................. 93 

e. Co-occurrence Analysis................................................................................ 94 

C. Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps

.................................................................................................95 
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1. Assumptions, Limitations, and Uncertainties Related to Exposure For All 

Taxa.............................................................................................95 

a. Maximum Use Scenario............................................................95 

2. Assumptions, Limitations and Uncertainties Related to Exposure For Aquatic 

Species ...................................................................................................................... 95 

a. Environmental Fate Studies.........................................................95

b. Aquatic Exposure Model .............................................................................. 95 

b. Bioaccumulation Modeling........................................................................... 96 

3. Assumptions, Limitations and Uncertainties Related to Exposure for Terrestrial 

Species ...................................................................................................................... 96 

a. Location of Wildlife Species ........................................................................ 96 

b. Routes of Exposure....................................................................................... 96 

c. Dietary Intake and Other Limitations of Oral Studies in Terrestrial Species96 

d. Incidental Releases Associated With Use..................................................... 98 

e. Residue Levels Selection .............................................................................. 99 

f. TerrPlant Model............................................................................................ 99 

4. Assumptions, Limitations and Uncertainties Related to Effects Assessment .. 99 

a. Sublethal Effects........................................................................................... 99

b. Age Class and Sensitivity of Effects Thresholds.......................................... 99

c. Use of Most Sensitive Species Tested ........................................................ 100

5. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to 

the Acute and Chronic LOC’s................................................................................. 100

V. LITERATURE CITED ........................................................................................ 101

VI. APPENDICES................................................................................................... 109

VII. LIST OF FIGURES......................................................................109

VIII. LIST OF TABLES........................................................................109
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I. Executive Summary

A. Nature of the Chemical Stressor

Metrafenone (3-bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-

methylphenyl)methanone; CAS Reg. No. 220899-03-6) is a new pesticide active 

ingredient submitted for registration in the United States. Metrafenone is a benzophenone 

fungicide with resistance code U8 (unknown mode of action). What is known is that the 

chemical inhibits growth of mycelium on the leaf surface, leaf penetration, formation of 

haustoria, and sporulation of the target fungus, Uncinula necator (EPA Pesticide Fact 

Sheet 2006). Metrafenone likely affects actin proteins which play a role in cell function 

and cell division (Opalski et al. 2006). It has a local inhibition effect; in other words, it is 

not systemic and not a contact killer. 

As a new pesticide active ingredient, the actual usage of metrafenone is not known. The 

end-use product Metrafenone 300 SC is proposed for use on grapes to treat powdery

mildew; it is used for preventive but not curative measures. Ground (liquid) application is 

the proposed method of application. The maximum single application rate is 0.300 lbs 

a.i./A; at 6 applications per season, the seasonal maximum rate is 1.80 lbs a.i./A. The 

minimum application interval is 14 days.

B. Potential Risks to Non-target Organisms

The results of this screening-level assessment indicate a potential for direct adverse 

effects to non-target mammals (dose-based RQs 1.14-2.91) following chronic exposure; 

these RQs also exceed the federally listed species LOC. Due to the potential for direct 

adverse effects to mammals associated with the application of metrafenone on grapes, 

indirect effects may consequently affect other aquatic and terrestrial species. Data were 

either not submitted or were deemed invalid for freshwater invertebrates and 

marine/estuarine fish via chronic exposure. Without data, risk cannot be ruled out for 

these taxa (either non-listed or federally listed species). Non-definitive endpoints – in this 

case, where total concentrations were estimated instead of the preferred dissolved 

concentrations in the majority of aquatic studies on metrafenone – suggest potential 

chronic risk to federally listed freshwater fish and acute risk to federally listed 

marine/estuarine invertebrates. Comparison of the non-definitive endpoints with aquatic 

EECs indicates potential risk to the given federally listed taxa (see Section I.F below, 

Table 3) but not the non-listed taxa summarized in Table 1 and Table 2. 
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Table 1. Summary of Environmental Risk Conclusions for Aquatic Animals and Plants from Metrafenone

Use on Grapes at the Maximum Proposed Application Rate (0.3 lb a.i./A, Assuming 6 Applications/Year)*

Taxonomic 

Group

Assessment 

Endpoint

Summarized Risk Characterization and Important 

Uncertainties

Freshwater Fish 

and Aquatic Phase 

Amphibians

Mortality Acute risk is not expected (from technical grade active ingredient, 

metabolites, and EU/UK formulation).

Reproduction, 

growth etc.

Chronic risk is not expected.

Freshwater 

Invertebrates

Mortality Acute risk is not expected (from technical grade active ingredient, 

metabolites, and EU/UK formulation).

Reproduction, 

growth etc.

No acceptable studies available. Chronic risk cannot be precluded.

Marine/

Estuarine Fish

Mortality Acute risk is not expected.

Reproduction, 

growth etc.

No studies submitted. Chronic risk cannot be precluded.

Marine/

Estuarine 

Invertebrates

Mortality Acute risk is not expected.

Reproduction, 

growth etc.

Chronic risk is not expected.

Aquatic Plants

Acute Risk Risk to vascular species is not expected from technical grade active 

ingredient. In addition, risk to non-vascular species is not expected

(from the technical grade active ingredient, metabolites, and EU/UK

formulation).

* Consult ‘Risk Description’ section for further details. Also, risk in this table implies risk to technical grade 

active ingredient unless otherwise specified that metabolites and formulations were assessed as well. 

Table 2. Summary of Environmental Risk Conclusions for Terrestrial Animals and Plants from

Metrafenone Use on Grapes at the Maximum Proposed Application Rate (0.3 lbs a.i./A, Assuming 6

Applications/Year)*

Taxonomic 

Group Risk Endpoint

Summarized Risk Characterization and Important 

Uncertainties

Birds, Reptiles and 

Terrestrial Phase 

Amphibians

Mortality Acute risk is not expected. 

Reproduction, 

growth etc.

Chronic risk is not expected.

Mammals

Mortality Acute risk is not expected.

Reproduction, 

growth etc.

Chronic risk is expected.

Non-target 

Invertebrates Acute Risk

Acute risk to honeybees is not expected. Acute risk to earthworms 

(from the technical grade active ingredient, a metabolite, and 

EU/UK formulation) is not expected.

Terrestrial Plants Acute Risk Risk to terrestrial plants is not expected (from EU/UK formulation).

* Consult ‘Risk Description’ section for further details. Also, risk in this table implies risk to technical grade 

active ingredient unless otherwise specified that metabolites and formulations were assessed as well.

C. Environmental Fate Summary

While metrafenone is expected to be slightly mobile, its major routes of degradation are 

aqueous photolysis and aquatic metabolism, in both aerobic and anaerobic conditions. 
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Soil metabolism is slow, with laboratory half-lives of 6 months to a year and 

accumulation over two years observed in field studies. In aquatic environments, the 

measured photolysis half-life was 6.4 days and metabolism in both aerobic and anaerobic 

occurred with half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to one major 

degradate, CL 377160 [Methanone, (3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy2,4-dimethoxy-6-methylphenyl)-], and anaerobic aquatic metabolism also led to six other 

major degradates, but all were either unidentified or only tentatively identified. In 

addition, there were many minor degradates, which were formed at low levels 

individually but reached substantial amounts as groups. 

Tier II aquatic exposure modeling was conducted for parent metrafenone and 

metrafenone residues (metrafenone+ extractable residues) (Table 11). This modeling 

approach was used to address uncertainties associated with identification of metrafenone 

residues in soil and sediment. The highest aquatic EECs for metrafenone were 11.70 

μg/L for the daily peak, 8.82 μg/L for the 21 day average, and 6.21 μg/L for the 60 day

average. The highest aquatic EECs for total metrafenone residues were 20.22 μg/L for the 

daily peak, 17.67 μg/L for the 21 day average, and 16.98 μg/L for the 60 day average.

No monitoring data are available to compare with model estimates. Bioaccumulation 

modeling was conducted because metrafenone has a log octanol:water coefficient > 4. 

Maximum residue concentrations in fish are expected to range from 17,636 to 19,586 

μg/kg-ww. 

D. Ecological Effects Summary

Aquatic Organisms

The greatest amount of uncertainty in the assessment stems from aquatic studies which 

were largely based on total concentrations (both dissolved and undissolved) of the test 

compound. In all cases (except for the chronic study on the saltwater mysid, but including 

aquatic plants), the risk quotient values were not calculated. However, given comparisons 

of the total concentrations for most available studies and soluble concentrations for the 

saltwater mysid (chronic) and sheesphead minnow (acute) to respective EEC values the 

implication is that acute and chronic risk (including sublethal effects) to aquatic 

organisms (including aquatic plants) is not expected as a result of metrafenone use on 

grapes. However, the taxa for which studies were either submitted and deemed 

unacceptable (chronic freshwater invertebrate studies) or not submitted at all (chronic 

marine/estuarine fish), the risk as a result of metrafenone use cannot be precluded.

Terrestrial Organisms

The acute oral avian studies indicated no effects; the acute dietary avian studies indicated 

a significant change in body weight that was not associated with a dose-response pattern. 

In the acute mouse study on the technical grade active ingredient, only one mortality was 

reported. Therefore, no implications with lethal or sublethal acute effects can be made 
Page 11 of 114

for either avian or mammalian taxa. Metrafenone is classified as ‘practically non-toxic’ to 

honeybees and non-lethal to earthworms up to the limit concentration. Therefore, the 

implication is that acute risk to terrestrial invertebrates is not expected as a result of 

metrafenone use on grapes. In addition, no terrestrial plant risks are expected as a result 

of use of the EU/UK formulation; however, no data on terrestrial plants are available on 

the U.S. formulation.

The avian chronic toxicity endpoint (NOAEC 848 mg a.i./kg diet) based on egg 

production and hatchability did not yield chronic LOC exceedances. The most sensitive 

chronic mammalian endpoint (NOAEL 35.9 mg/kg bw/day) based on decreased body

weights and body weight gain in F1 males as well as body weights in F1 and F2 females, 

however, exceeded the chronic LOC, which implies that sublethal chronic effects on 

mammals are expected under field conditions. Therefore, given the LOC exceedance 

chronic risk to mammals is expected as a result of metrafenone use on grapes.

E. Uncertainties and Data Gaps

1. Environmental Fate and Exposure

All but one of the environmental fate studies required to support the registration 

of metrafenone for use on grapes were submitted. Independent Laboratory Validations 

for the methods submitted for analysis of metrafenone in soil and water remain a data 

gap. These data gaps fall under the terrestrial field dissipation study guideline (835.6100).

For a list of submitted environmental fate studies for metrafenone see Appendix F.

All of the environmental fate studies for the parent compound were determined to 

be scientifically valid and therefore results from all of the studies can be used to 

characterize the mobility and rates of transformation of metrafenone. However, many of 

the metabolism studies have major uncertainties in the identification and pattern of 

formation and decline of transformation products. In all of the aquatic metabolism 

studies, between 57% and 65% of the applied radioactivity remains unidentified with 

incomplete characterization, and in two aerobic soil metabolism studies, 15% and 44% of 

the applied radioactivity is unidentified. This includes at least four major degradates that 

individually reach levels of 11% to 35% of the applied. Other transformation products 

appear as groups of up to 15 components, in some cases characterized as each being <5% 

of the applied radioactivity, but in other cases, some individual components make up 9% 

to 10% of the applied. Even when individual components can all be classified as minor 

degradates, these groups represent such a large portion of the applied radioactivity overall 

that the possibility that they may have some impact as a group cannot be precluded 

despite their lower individual levels. This is especially true given that the degradation 

pathways suggest that groups of degradates may have a high degree of structural 

similarity and so may have similar fate and effects behavior. Without information to 

adequately characterize the degradates, it was necessary to assume that they are of equal 

toxicity to the parent in order to quantify risks for metrafenone extractable residues.
Page 12 of 114

In addition to the studies submitted by the registrant, EFED was provided with a 

Draft Assessment Report (DAR) on Metrafenone written by the United Kingdom. That 

assessment reports that the long dissipation time observed in field studies triggered a 

requirement for longer term field accumulation studies. Two years into those five year 

studies, results show that metrafenone appears to be accumulating, and that metrafenone 

residues have been detected as deep as 20-30 cm below the surface. These studies would 

provide useful information regarding the environmental fate of metrafenone and would 

assist in reducing uncertainties. 

2. Ecological Effects Data

The submitted ecotoxicity database is incomplete. The greatest amount of 

uncertainty in the assessment stems from aquatic studies which were largely based on 

total (both dissolved and undissolved) concentrations of test compound; that is, the 

concentrations were measured without centrifugation even though precipitate was 

observed or test was conducted at the solubility limit of the metrafenone technical grade 

active ingredient; the solubility limits of the metabolites are unknown. To reduce 

uncertainty the majority of the toxicity studies, which are considered supplemental, and

cannot be used in a quantitative risk estimation would need to be redone; especially those 

where mortality or sublethal effects were observed. These aquatic studies are specified 

below. For a list of submitted ecological effects studies for metrafenone see Appendix G.

The following studies are considered data needs: 

Aquatic studies

Given the freshwater fish studies on metrafenone technical grade active ingredient and 

assuming that the concentrations in the environment reach the solubility limit, the effect 

of the compound is likely to be low. However, according to model estimated EECs 

(which include metrafenone and metrafenone residue scenarios: 0.00153 - 0.02 mg/L), 

levels of metrafenone (TGAI, TEP)1at the solubility limit (0.2-0.5 mg/L at 12oC) and 

metrafenone metabolites at the tested concentrations are not expected to occur in the 

environment given the proposed grape use. Therefore, acute risk to freshwater fish and 

aquatic-phase amphibians is not expected as a result of metrafenone use on grapes. In 

addition, although the EU/UK formulation – with which the submitted studies were 

conducted – closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not its 

equivalent. Therefore, the effect of the U.S. formulated product on freshwater fish and 

aquatic-phase amphibians is not known.

To reduce uncertainty in characterizing risk, which is currently based on total 

concentrations, the freshwater fish studies on bluegill sunfish (Lepomis macrochirus) are 

requested to make same species comparisons for acute and chronic values. Bluegill was 

chosen over the rainbow trout due to greater sensitivity (on an acute basis) of the bluegill 

to the TGAI relative to the trout. Since the acute marine/estuarine fish study is acceptable 

and given the above two studies, the acute to chronic ratio can be utilized to estimate 

 

1 TGAI: technical grade active ingredient; TEP: typical end-use product (formulation)
Page 13 of 114

marine/estuarine chronic endpoints, negating the need to fill this data gap. Special 

emphasis must be placed on centrifuging the test samples prior to analytical 

determination of the test compound.

 Acute: Freshwater fish toxicity (96-hour LC50 for Lepomis macrochirus) 

(850.1075; 72-1), TGAI

 Chronic: Fish early-life stage (freshwater: Lepomis macrochirus) (850.1400; 72-

4), TGAI

Although acute freshwater invertebrate studies were based on total concentrations, no 

effects were observed with the TGAI, negating the need to request additional data. 

However, a chronic freshwater invertebrate data gap still exists since the two reviewed 

studies were deemed invalid.

Chronic: Aquatic invertebrate life cycle (freshwater: Daphnia magna) (850.1300; 

72-4), TGAI

Effects were observed in both acute marine/estuarine invertebrate studies with the TGAI 

on the eastern oyster (Crassostrea viginica) and saltwater mysid (Americamysis bahia) 

but the endpoints are based on total concentrations. Therefore, should concentrations in 

the environment reach the solubility limit, the acute risk to marine/estuarine invertebrates 

may be expected. However, according to the model estimated EECs (0.00153 - 0.02 

mg/L, which includes metrafenone and total metrafenone residue scenarios), levels of 

metrafenone at the solubility limit are not expected to occur in the environment given the 

proposed grape use. Given these studies and assuming that metrafenone concentrations in 

the environment are not likely to reach the solubility limit, the acute risk to 

marine/estuarine invertebrates is not expected. However, to reduce uncertainty in 

characterizing risk, either study is requested to be redone with special emphasis on 

centrifuging the test samples prior to analytical determination of the test compound.

Acute: Marine/estuarine invertebrate either Crassostrea virginica (850.1025; 72-

3) or Americamysis bahia (850.1035; 72-3), TGAI 

A non-guideline chronic midge study (Chironomus riparius) with metrafenone technical 

(97.1%) was deemed invalid on the basis of low negative control emergence. Therefore, a

chronic freshwater invertebrate whole sediment study is requested. A protocol should be 

submitted for approval prior to study initiation. The protocol should include spiked 

sediment. The whole sediment study is requested because metrafenone has a high logKow

value (4.3 at 25oC, pH 4) and a high aerobic soil half life (> 4 months), which indicates 

that the compound may partition to sediment and persist.

 Chironomus dilutus (freshwater) using TGAI. Consult EPA Test Method 100.5 

Life-cycle Test for Measuring the Effects of Sediment Associated 

Contaminants on Chironomus dilutus (formerly Chironomus tentans) and 

OECD Guideline 218 Sediment-Water Chironomid Toxicity Test Using 

Spiked Sediment
Page 14 of 114

Non-target aquatic plant studies were also based on total concentrations leading to 

uncertainty in exposure concentrations and thus endpoint values. Had valid endpoints 

(i.e., those based on dissolved concentrations) been determined using these studies, they

would likely be greater than the highest model predicted concentration in the 

environment, which implies that risk to vascular and non-vascular species is not expected 

as a result of metrafenone use on grapes. However, without centrifugation, the amount of 

chemical that is freely dissolved and bioavailable cannot accurately be determined. 

Therefore, vascular and non-vascular aquatic plant studies are requested with special 

emphasis placed on centrifuging the test samples prior to analytical determination of the 

test compound. In addition, cyanobacteria yielded no effects given total concentrations 

and does not need to be redone.

 Aquatic vascular plant growth (Lemna spp.), Tier II (850.4400), TGAI

 Aquatic non-vascular plant growth, Tier II (850.5400), TGAI

 Terrestrial Studies

An avian acute oral toxicity test in passerine species is required. Passerines are the most 

common birds (in terms of numbers and number of species) in the United States. Many

utilize agricultural fields, forests, residential areas and surrounding areas, and, therefore, 

have the potential to be exposed to pesticides used in agricultural, forest, and residential 

settings. It is likely that, for the requested use patterns, passerines are more likely to be 

exposed to metrafenone than upland game species and waterfowl. Passerines are smaller 

and have a higher energy requirement than larger-sized birds. As such, passerines may

be more sensitive than other birds. 

 Passerine bird toxicity study (EPA approved protocol is required prior to study

initiation): Avian acute oral toxicity test (850.2100, 71-1), TGAI

Formulated Product Testing

The available formulation product studies were conducted using three different UK/EU 

formulated products (i.e., BAS 560 00F, BAS 560 01F, and BAS 560 02F), one of which 

(BAS 560 00F) closely matches the U.S. formulation (i.e., BAS 560 03F). Formulation 

studies in this assessment are based on BAS 560 00F because data on the U.S. 

formulation were not submitted. In order to eliminate uncertainty in effects 

characterization of formulated products used within the U.S. on given taxa, future 

registrant submitted studies should be based on the U.S. formulation. At this time the 

effect of the U.S. formulation on given taxa is not known, however, greater toxicity of the 

EU/UK formulation on the honeybee relative to the TGAI was observed. Similarly, data 

submitted for terrestrial plants is based on the EU/UK formulation. As a result, the 

following studies are requested: 

 Honeybee acute contact toxicity (850.3020, 141-1), TEP

 Seedling emergence, Tier II (850.4225, 123-1), TEP

 Vegetative vigor, Tier II (850.4250, 123-1), TEP
Page 15 of 114

F. Endangered Species Considerations

Table 3 summarizes the listed species at risk associated with either direct or indirect 

effects following application of metrafenone for the proposed uses.

Concerns For Federally Listed as Endangered and/or Threatened Species

Table 3. Listed Species Risks Associated With Direct or Indirect Effects from Metrafenone use on 

Grapes at the Maximum Proposed Application Rate (0.3 lbs a.i./A, Assuming 6 Applications/Year)

Listed Taxon Direct Effects Indirect Effects

Terrestrial and semi-aquatic plants - monocots No Yes from effects to mammals

Terrestrial and semi-aquatic plants – dicots No Yes from effects to mammals

Terrestrial invertebrates No Yes from effects to mammals

Birds No Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Terrestrial-phase amphibians No Yes from effects to mammals

Reptiles No Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Mammals Yes for chronic1 Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

 Aquatic non-vascular plants No Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Aquatic vascular plants No Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Freshwater (FW) fish Yes for chronic2 Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Aquatic-phase amphibians Yes for chronic3 Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Freshwater (FW) invertebrates Yes for chronic4 Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Marine/estuarine (M/E) fish Yes for chronic4 Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

Marine/estuarine (M/E) invertebrates (mollusk) Yes for acute5, 

No for chronic6

Yes from effects to mammals, FW 

fish, FW inverts, M/E fish, M/E 

inverts (mollusks)

1 The chronic LOC is exceeded on a dose basis for mammals in all size classes eating short grass, for the 15 and 35 gram size 

classes eating tall grass and broadleaf plants / small insects. The chronic LOC on a dietary basis is not exceeded for any of the 

food categories. 

2 The total concentration based endpoint (NOAEC: 0.118 mg total a.i./L) for the chronic freshwater fish (fathead minnow) 

study (MRID 47267449) with an effect on post-hatch survival is approximately 7x greater than the highest estimated EEC 

(0.016 mg/L), hence risk to federally listed freshwater fish cannot be precluded.

3 Results from freshwater fish used as surrogate for assessing risk to aquatic-phase amphibians

4

Studies not submitted or invalid for which risk cannot be precluded.

5 Mollusk (Eastern oyster); 6

Saltwater mysid
Page 16 of 114

II. Problem Formulation

The purpose of this problem formulation is to provide the foundation for the ecological 

risk assessment being conducted for the fungicide metrafenone. As such, it articulates the 

purpose and objectives of the risk assessment, evaluates the nature of the problem, and 

provides a plan for analyzing the data and characterizing the risk (EPA, 1998). 

A. Nature of Regulatory Action

Metrafenone is a new pesticide active ingredient being proposed as a fungicide to control 

powdery mildew on grapes. As a new active ingredient submitted for registration, there 

are no previously prepared ecological risk assessments by the Agency for metrafenone 

uses. However, the European Commission has issued a Dossier for Metrafenone2(DAR

2005). 

B. Stressor Source and Distribution

The stressor is the metrafenone and its unidentified, extractable degradation products 

when applied to grapes to control powdery mildew. Therefore, metrafenone could 

potentially be used anywhere in the United States where grapes are grown.

1. Nature of the Chemical Stressor

Figure 1 provides the chemical structure of metrafenone. Table 4 identifies the physical 

and chemical properties of metrafenone from experimental data.

Figure 1. Chemical Structure of Metrafenone

 

2 EC Directive 91/414.
Page 17 of 114

Table 4. Environmental Fate Properties of Metrafenone

PARAMETER VALUE(S) (units) SOURCE COMMENT

 Chemical Name (3-Bromo-6-methoxy-2-

methylphenyl)(2,3,4-trimethoxy6-methylphenyl)-methanone

– –

 Molecular Formula C19H21BrO5.

 Molecular Weight 409 _ –

 Solubility (20 oC) 0.474 mg/L or ppm MRID: 46415711 “Slightly soluble” according to 

FAO Classification

 Vapor Pressure (20 oC) 1.15 x 10-6 mmHg MRID: 46415713 –

 Henry’s Law constant 1.3 x 10-6 atm-m

3

/mole Estimated from vapor pressure 

and water solubility.

 pKa (20 oC) None MRID: 46415714 –

Octanol-Water Partition 

Coefficient 

(Log KOW, at 25 oC, pH 4)

4.3 MRID: 46415715 –

 Hydrolysis Half-life 

 (pH 5, 7, 9; (50 oC))

Stable MRID: 47267422 Stable at all pHs.

 Aqueous Photolysis Half-life 

 (pH 5)

t1/2 = 6.4 days MRID: 47267423 Value corrected to represent 

natural sunlight at 40°N 

latitude; uncorrected lab halflife of 3.2 days (continuous 

irradiation; xenon lamp).

 Soil Photolysis Half-life t1/2 = 31 days MRID: 47267424 –

Aerobic Soil Metabolism 

Half-life

Silt loam: t1/2 = 178-277 d

Sandy loam: t1/2 = 277, 365 d

Clay loam: t1/2 = 299, 330 d

Loamy sand: t1/2 = 182 d

DT50 = 160 – 270 d

MRIDs: 

47267425

47267426

47267427

8 systems, 4 conducted with 

foreign soils.

In 2 studies metrafenone 

residues exceeded 50% at study 

termination (120 & 210 d)

 Anaerobic Aquatic Metabolism 

 Half-life

t1/2 = 21.6 d, 18.0 d

DT50 = 15 d, 3 d

MRIDs:

47267429

47267431

–

 Aerobic Aquatic Metabolism 

 Half-life

t1/2 = 27.3 d, 24.1 d

DT50 = 10 d, 11 d

MRID: 47267430 –

 Organic Carbon Partition

 Coefficient (KOC)

1073, 2230, 2331, 

22517, 2792 mL/gOC

MRID: 47267420 “Slightly mobile” according to 

FAO Classification

 Soil Partition Coefficient (Kd) 15.1, 36.5, 40.1,

42.0, 86.5 mL/g

MRID: 47267420 --

Terrestrial Field Dissipation t1/2 =144 d, 161 d, 210 d, 161 d MRID 47267432 Field studies were conducted in 

WA, ON,CA, FL

Bioaccumulation in Fish BCF: 140 to 530 MRID 47267450 Lipid Normalized BCF
Page 18 of 114

a. Mode of Action (MoA) of Metrafenone

Metrafenone is a benzophenone fungicide. What is known is that the chemical inhibits 

growth of mycelium on the leaf surface, leaf penetration, formation of haustoria, and 

sporulation of the target fungus, Uncinula necator (EPA Pesticide Fact Sheet 2006).

Metrafenone likely affects actin proteins which play a role in cell function and cell 

division (Opalski et al. 2006).

b. Reactions of Metrafenone in the Environment

Metrafenone is expected to be slightly mobile. Its major routes of degradation are 

aqueous photolysis and aquatic metabolism, in both aerobic and anaerobic conditions. 

Soil metabolism is slow, with laboratory half-lives of 6 months to a year and 

accumulation over two years observed in field studies. In aquatic environments, the 

measured photolysis half-life was 6.4 days and metabolism in both aerobic and anaerobic 

occurred with half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to one major 

degradate, CL 377160, and anaerobic aquatic metabolism also led to six other major 

degradates, but all were either unidentified or only tentatively identified. In addition, 

there were many minor degradates, which were formed at low levels individually but 

reached substantial amounts as groups. 

2. Overview of Pesticide Usage

As a new pesticide active ingredient, the actual usage of metrafenone is not known. The 

end-use product Metrafenone 300 SC is proposed for use on grapes.

Ground application is the proposed method of application. The label states, “do not apply

directly to water, to areas where surface water is present, or to intertidal areas below the 

mean high water mark.” The chemical is to be applied at most 6 times per season at a 

maximum application rate of 0.3 lbs a.i./A (Table 5). The label also states, “do not make 

more than 2 sequential applications of Metrafenone 300 SC fungicide before alternating 

to a labeled fungicide with a different mode of action.”

Table 5. Metrafenone use and application information based on the proposed label for 

Metrafenone 300 SC

Use

Max. Single 

App. Rate 

(lbs a.i./A)

# of 

App. /

Season

Seasonal Max. 

Rate (lbs a.i./A)

Minimum App. 

Interval (days)

Grapes 0.300 6 1.80 14 days

C. Receptors

1. Aquatic and Terrestrial Effects

The receptor is the biological entity that is exposed to the stressor (EPA, 1998). Based on 

the proposed uses for metrafenone, it is expected that the aquatic and terrestrial receptors 

will include freshwater fish and invertebrates, marine/estuarine fish and invertebrates, 
Page 19 of 114

aquatic plants, terrestrial plants, birds, mammals, and terrestrial invertebrates.

Consistent with the process described in the Overview Document (EPA, 2004), this risk 

assessment uses a surrogate species approach in its evaluation of metrafenone. 

Toxicological data generated from surrogate test species, which are intended to be 

representative of broad taxonomic groups, are used to extrapolate to potential effects on a 

variety of species (receptors) included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrants are used 

to evaluate the potential direct effects of metrafenone to the aquatic and terrestrial 

receptors identified in this section. This includes toxicity data on the technical grade 

active ingredient, any major transformation products, and when available, formulated 

products (e.g. “Six-Pack” studies). 

Table 6 provides a summary of the taxonomic groups and the surrogate species tested to 

help understand potential acute ecological effects of pesticides to these non-target 

taxonomic groups. In addition, the table provides a preliminary overview of the potential 

acute toxicity of metrafenone by providing the acute toxicity classifications.

Table 6. Test Species Evaluated for Assessing Potential Ecological Effects of Metrafenone and the 

Associated Acute Toxicity Classification

Taxonomic Group Surrogate Species Acute Toxicity Classification

Birds1

Mallard Duck (Anas platyrhynchos)

Bobwhite Quail (Colinus virginianus)

Passerine species

Practically nontoxic

Practically nontoxic

No available study

Mammals Laboratory rat (Rattus norvegicus)

Laboratory mouse

Practically non-toxic

Practically non-toxic

Insects Honey bee (Apis mellifera L.) Practically non-toxic

Freshwater fish2 Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Highly toxic

Highly toxic

Freshwater invertebrates Water flea (Daphnia magna) At most, highly toxic

Marine/estuarine fish Sheepshead minnow (Cyprinodon variegatus) Highly toxic

Marine/estuarine

invertebrates

Mysid shrimp (Americamysis bahia)

Eastern oyster (Crassostrea virginica)

Highly toxic

Highly toxic

Terrestrial plants3 Monocots – most sensitive species

Dicots – most sensitive species No Classification

Aquatic plants and algae

Duckweed (Lemna gibba) 

Cyanobacteria/blue-green algae (Anabaena flos-aquae)

Marine diatom (Skeletonema costatum)

Freshwater diatom (Navicula pelliculosa)

Algae (Pseudokirchneriella subcapitata; previously 

known as Selenastrum capricornutum)

No classification

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles.

2

Freshwater fish may be surrogates for aquatic-phase amphibians.

3 Normally four species of two families of monocots, of which one is corn; six species of at least four dicot families, of which one is 

soybeans.
Page 20 of 114

2. Ecosystems Potentially at Risk

The ecosystems at risk are often extensive in scope, and as a result it may not be possible 

to identify specific ecosystems during the development of a baseline risk assessment. 

However, in general terms, terrestrial ecosystems potentially at risk could include the 

treated field and areas immediately adjacent to the treated field that may receive drift or 

runoff. Areas adjacent to the treated field could include cultivated fields, fencerows and 

hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats, and other 

uncultivated areas. 

Aquatic ecosystems potentially at risk might include but are not necessarily limited to 

water bodies adjacent to, or down stream from, the treated field and might include 

impounded bodies such as ponds, lakes and reservoirs, or flowing waterways such as 

streams or rivers. For uses in coastal areas, aquatic habitat also includes marine 

ecosystems, including estuaries.

D. 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 (EPA, 1998). Generally, the ecological entities may include the following: 

freshwater as well as marine/estuarine fish and invertebrates, aquatic and terrestrial 

plants, birds, reptiles, amphibians, mammals, and non-target insects. For metrafenone: 

chronic risk to mammals is expected. The attributes for each of these entities may include 

growth, reproduction, and survival. 

E. Conceptual Model

A conceptual model provides a written description and visual representation of the 

predicted relationships between metrafenone residues, potential routes of exposure, and 

the predicted effects for the assessment endpoint. A conceptual model consists of two 

major components: risk hypothesis and a conceptual diagram (EPA, 1998).

1. Risk Hypothesis

For a pesticide to pose an ecological risk, it must reach ecological non-target organisms 

(receptors) at biologically significant concentrations. An exposure pathway is the means 

by which a pesticide moves in the environment from the application site to non-target 

organisms. The evaluation of the ecological exposure pathways in this assessment 

includes an examination of the source and potential transport pathways for metrafenone 

and the determination of exposure routes of non-target species. 

Metrafenone, when used in accordance with the label, results in potential direct adverse 

effects upon the growth and reproduction of mammals. As a result, given the persistence 

of metrafenone, there is potential for indirect effects to terrestrial and/or aquatic 
Page 21 of 114

organisms.

2. Conceptual Diagram

The conceptual model diagram is a generic graphic depiction of the risk hypotheses 

identified in the previous section. It is assumed that metrafenone is capable of affecting 

exposed terrestrial and aquatic organisms if environmental concentrations are sufficiently 

elevated as a result of proposed label uses. Through a preliminary process of examining 

fate and effects data, the risk hypotheses and conceptual model have been refined to 

reflect possible exposure pathways and the organisms that are most relevant and 

applicable to this assessment (Figure 2). If exposed at sufficient levels, mortality may

occur, as well as sublethal effects. Direct effects on a taxonomic group may result in 

indirect effects (i.e., loss of habitat, food resources) to other taxonomic groups. This 

assessment will examine the potential for these effects to occur within the surrogate taxa 

with the intent to extrapolate to actual effects within the environment.

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a 

contaminant moves in the environment from a source to an ecological receptor. For this 

pathway to be complete, it must have a source, a release mechanism, an environmental 

transport medium for metrafenone and/or its transformation products, a point of exposure 

for ecological receptors, and a feasible route of exposure. The assessment of these 

pathways thus includes an examination of the sources and potential migration pathways 

for constituents, and the determination of potential exposure routes. 

The conceptual model for both potential aquatic and terrestrial risk is shown in Figure 2. 

Exposure routes shown in dashed lines are not quantitatively considered because the 

resulting exposures are expected to be very low when compared to the major routes of 

exposure.

Exposure is expected to be dominated by runoff and spray drift. Metrafenone exposure 

may also result from off-site movement in runoff water and on metrafenone -bearing soil 

particulates to adjacent fields (soil erosion). The moderate Koc’s (Koc 1073 to 22517 

L/kg-oc) of metrafenone suggest that leaching to ground water/recharge to surface water 

would not be a route of exposure. Long-range transport of metrafenone in the gas phase is 

not considered a significant route of exposure.

This screening-level assessment for ground spray applications of metrafenone only

considered dietary exposure. Other routes of exposure that were not considered in the 

assessment are incidental soil ingestion exposure, inhalation exposure, dermal exposure, 

and drinking water exposure. These routes are not represented in the diagram (Figure 2). 
Page 22 of 114

Figure 2. Conceptual Model Depicting Sources of Exposure from Metrafenone as 

well as Metrafenone Residues, Potential Receptors, and Adverse Effects from the 

Proposed Uses of Metrafenone on Grapes.

F. Analysis Plan

The structure of this risk assessment is based on guidance contained in U.S. EPA’s 

Guidance for Ecological Risk Assessment (U.S. EPA, 1998) and is consistent with 

procedures and methodology outlined in the Overview Document (U.S. EPA, 2004).

1. Conclusions from Previous Risk Assessments

There are no previous ecological risk assessments because this is the first registration 

petition for metrafenone for use on grapes in the United States. 

2. Preliminary Identification of Data Gaps

Review of the submitted studies indicated the following points:

Stressor

Metrafenone applied as foliar spray with ground equipment on grapes l 

Source/

Transport

Pathways

Direct

Deposition

Spray

Drift

Runoff/

Erosion

Leaching

(Infiltration/

Percolation

Source/

Exposure

Media

Terrestrial Food 

Residues (foliage, 

fruit, insects

Upland

Foliage/Soil

Riparian/

Wetland 

Foliage/Soil

Receiving 

Water Body/ 

Sediment

Groundwater

Exposure

Route

Ingestion Direct contact/

Root Uptake

Direct contact/

Root Uptake

Gill/

Integument 

Uptake

Receptors

Attribute

Changes

Terrestrial Vertebrates

Birds, Mammals,

Reptiles, Terrestrial 

Phase Amphibians

Terrestrial

Upland

Plants

Individual Animals

Reduced survivall

Reduced growth

Reduced 

reproduction

Aquatic 

Invertebrates

Aquatic 

Vertebrates

Wetland/ 

Riparian

Plants

Individual Plants

Seedling emergence

Vegetative vigor

Individual 

vertebrates and 

invertebrates

Reduced

survivall

Reduced

growth

Reduced

reproduction

Plant 

population

Reduced

population

growth

Aquatic 

Plants

Uptake/ 

Adsorption
Page 23 of 114

Environmental Fate

All but one of the environmental fate studies required to support the registration 

of metrafenone for use on grapes were submitted. Independent Laboratory Validations 

for the methods submitted for analysis of metrafenone in soil and water remain a data 

gap. For a list of submitted environmental fate studies for metrafenone see Appendix F.

All of the environmental fate studies for the parent compound were determined to 

be scientifically valid and therefore results from all of the studies can be used to 

characterize the mobility and rates of transformation of metrafenone. However, many of 

the metabolism studies have major uncertainties in the identification and pattern of 

formation and decline of transformation products. In all of the aquatic metabolism 

studies, between 57% and 65% of the applied radioactivity remains unidentified with 

incomplete characterization, and in two aerobic soil metabolism studies, 15% and 44% of 

the applied radioactivity is unidentified. This includes at least four major degradates that 

individually reach levels of 11% to 35% of the applied. Other transformation products 

appear as groups of up to 15 components, in some cases characterized as each being <5% 

of the applied radioactivity, but in other cases, some individual components make up 9% 

to 10% of the applied. Even when individual components can all be classified as minor 

degradates, these groups represent such a large portion of the applied radioactivity overall 

that the possibility that they may have some impact as a group cannot be precluded 

despite their lower individual levels. This is especially true given that the degradation 

pathways suggest that groups of degradates may have a high degree of structural 

similarity and so may have similar fate and effects behavior. Without information to 

adequately characterize the degradates, it may be necessary to assume that they are of 

equal toxicity to the parents in order to quantify risks.

In addition to the studies submitted by the registrant, EFED was provided with a 

Draft Assessment Report (DAR) on Metrafenone written by the United Kingdom. That 

assessment reports that the long dissipation time observed in field studies triggered a 

requirement for longer term field accumulation studies. Two years into those five year 

studies, results show that metrafenone appears to be accumulating, and that metrafenone 

residues have been detected as deep as 20-30 cm below the surface. These studies would 

provide useful information regarding the environmental fate of metrafenone and would 

assist in reducing uncertainties. 

Ecotoxicity

The submitted ecotoxicity database is incomplete. The greatest amount of 

uncertainty in the assessment stems from aquatic studies which were largely based on 

total (both dissolved and undissolved) concentrations of test compound; that is, the 

concentrations were measured without centrifugation even though precipitate was 

observed or test was conducted at the solubility limit of the metrafenone technical grade 

active ingredient; the solubility limits of the metabolites are unknown. To reduce 

uncertainty the majority of the toxicity studies, which are considered supplemental, and 

cannot be used in a quantitative risk estimation would need to be redone; especially those 
Page 24 of 114

where mortality or sublethal effects were observed. These aquatic studies are specified 

below. For a list of submitted ecological effects studies for metrafenone see Appendix G.

The following studies are considered data needs: 

Aquatic studies

Given the freshwater fish studies on metrafenone technical grade active ingredient and 

assuming that the concentrations in the environment reach the solubility limit, the effect 

of the compound is likely to be low. However, according to model estimated EECs 

(which include metrafenone and metrafenone residue scenarios: 0.00153 - 0.02 mg/L), 

levels of metrafenone (TGAI, TEP)3at the solubility limit (0.2-0.5 mg/L at 12oC) and 

metrafenone metabolites at the tested concentrations are not expected to occur in the 

environment given the proposed grape use. Therefore, acute risk to freshwater fish and 

aquatic-phase amphibians is not expected as a result of metrafenone use on grapes. In 

addition, although the EU/UK formulation – with which the submitted studies were 

conducted – closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not its 

equivalent. Therefore, the effect of the U.S. formulated product on freshwater fish and 

aquatic-phase amphibians is not known.

To reduce uncertainty in characterizing risk, which is currently based on total 

concentrations, the freshwater fish studies on bluegill sunfish (Lepomis macrochirus) are 

requested to make same species comparisons for acute and chronic values. Bluegill was 

chosen over the rainbow trout due to greater sensitivity (on an acute basis) of the bluegill 

to the TGAI relative to the trout. Since the acute marine/estuarine fish study is acceptable 

and given the above two studies, the acute to chronic ratio can be utilized to estimate 

marine/estuarine chronic endpoints, negating the need to fill this data gap. Special 

emphasis must be placed on centrifuging the test samples prior to analytical 

determination of the test compound.

 Acute: Freshwater fish toxicity (96-hour LC50 for Lepomis macrochirus) 

(850.1075; 72-1), TGAI

 Chronic: Fish early-life stage (freshwater: Lepomis macrochirus) (850.1400; 72-

4), TGAI

Although acute freshwater invertebrate studies were based on total concentrations, no 

effects were observed with the TGAI, negating the need to request additional data. 

However, a chronic freshwater invertebrate data gap still exists since the two reviewed 

studies were deemed invalid. 

Chronic: Aquatic invertebrate life cycle (freshwater: Daphnia magna) (850.1300; 

72-4), TGAI

 

3 TGAI: technical grade active ingredient; TEP: typical end-use product (formulation)
Page 25 of 114

Effects were observed in both acute marine/estuarine invertebrate studies with the TGAI 

on the eastern oyster (Crassostrea viginica) and saltwater mysid (Americamysis bahia) 

but the endpoints are based on total concentrations. Therefore, should concentrations in 

the environment reach the solubility limit, the acute risk to marine/estuarine invertebrates 

may be expected. However, according to the model estimated EECs (0.00153 - 0.02 

mg/L, which includes metrafenone and total metrafenone residue scenarios), levels of 

metrafenone at the solubility limit are not expected to occur in the environment given the 

proposed grape use. Given these studies and assuming that metrafenone concentrations in 

the environment are not likely to reach the solubility limit, the acute risk to 

marine/estuarine invertebrates is not expected. However, to reduce uncertainty in 

characterizing risk, either study is requested to be redone with special emphasis on 

centrifuging the test samples prior to analytical determination of the test compound.

Acute: Marine/estuarine invertebrate either Crassostrea virginica (850.1025; 72-

3) or Americamysis bahia (850.1035; 72-3), TGAI 

A non-guideline chronic midge study (Chironomus riparius) with metrafenone technical 

(97.1%) was deemed invalid on the basis of low negative control emergence. Therefore, a

chronic freshwater invertebrate whole sediment study is requested. A protocol should be 

submitted for approval prior to study initiation. The protocol should include spiked 

sediment. The whole sediment study is requested because metrafenone has a high logKow

value (4.3 at 25oC, pH 4) and a high aerobic soil half life (> 4 months), which indicates 

that the compound may partition to sediment and persist.

 Chironomus dilutus (freshwater) using TGAI. Consult EPA Test Method 100.5 

Life-cycle Test for Measuring the Effects of Sediment Associated 

Contaminants on Chironomus dilutus (formerly Chironomus tentans) and 

OECD Guideline 218 Sediment-Water Chironomid Toxicity Test Using 

Spiked Sediment

Non-target aquatic plant studies were also based on total concentrations leading to 

uncertainty in exposure concentrations and thus endpoint values. Had valid endpoints 

(i.e., those based on dissolved concentrations) been determined using these studies, they

would likely be greater than the highest model predicted concentration in the 

environment, which implies that risk to vascular and non-vascular species is not expected 

as a result of metrafenone use on grapes. However, without centrifugation, the amount of 

chemical that is freely dissolved and bioavailable cannot accurately be determined. 

Therefore, vascular and non-vascular aquatic plant studies are requested with special 

emphasis placed on centrifuging the test samples prior to analytical determination of the 

test compound. In addition, cyanobacteria yielded no effects given total concentrations 

and does not need to be redone.

 Aquatic vascular plant growth (Lemna spp.), Tier II (850.4400), TGAI

 Aquatic non-vascular plant growth, Tier II (850.5400), TGAI
Page 26 of 114

 Terrestrial Studies

An avian acute oral toxicity test in passerine species is required. Passerines are the most 

common birds (in terms of numbers and number of species) in the United States. Many

utilize agricultural fields, forests, residential areas and surrounding areas, and, therefore, 

have the potential to be exposed to pesticides used in agricultural, forest, and residential 

settings. It is likely that, for the requested use patterns, passerines are more likely to be 

exposed to metrafenone than upland game species and waterfowl. Passerines are smaller 

and have a higher energy requirement than larger-sized birds. As such, passerines may

be more sensitive than other birds. 

 Passerine bird toxicity study (EPA approved protocol is required prior to study

initiation): Avian acute oral toxicity test (850.2100, 71-1), TGAI

Formulated Product Testing

The available formulation product studies were conducted using three different UK/EU 

formulated products (i.e., BAS 560 00F, BAS 560 01F, and BAS 560 02F), one of which 

(BAS 560 00F) closely matches the U.S. formulation (i.e., BAS 560 03F). Formulation 

studies in this assessment are based on BAS 560 00F because data on the U.S. 

formulation were not submitted. In order to eliminate uncertainty in effects 

characterization of formulated products used within the U.S. on given taxa, future 

registrant submitted studies should be based on the U.S. formulation. At this time the 

effect of the U.S. formulation on given taxa is not known, however, greater toxicity of the 

EU/UK formulation on the honeybee relative to the TGAI was observed. Similarly, data 

submitted for terrestrial plants is based on the EU/UK formulation. As a result, the 

following studies are requested: 

 Honeybee acute contact toxicity (850.3020, 141-1), TEP

 Seedling emergence, Tier II (850.4225, 123-1), TEP

 Vegetative vigor, Tier II (850.4250, 123-1), TEP

3. Measures of Exposure and Effects

EFED uses a tiered system of pesticide exposure modeling to assess ecological risk 

following a registered application of that pesticide. This tiered system is designed to 

minimize the amount of analysis which is required to register any given chemical. Each 

of the tiers is designed to screen out pesticides by requiring higher, more complex levels 

of investigation only for those that have not passed the next lower tier. Each tier screens 

out a percentage of pesticides from having to undergo a more rigorous review prior to 

registration or re-evaluation.
Page 27 of 114

a. Aquatic Exposure Models

Tier II PRZM and EXAMS4simulation models were used to estimate the exposure 

concentrations of metrafenone in surface water for the proposed use on grapes. The 

results are presented in Appendix B.

The data used as input parameters come solely from the environmental fate studies and 

proposed product label submitted by the petitioner to support in the United States the 

registration of metrafenone as a new pesticide-active ingredient for grapes. 

KABAM (KOW (based) Aquatic BioAccumulation Model) v.1.0 is used to estimate 

potential bioaccumulation of hydrophobic organic pesticides such as metrafenone (log 

Kow > 4) in freshwater aquatic food webs and subsequent risks to mammals and birds via 

consumption of contaminated aquatic prey. The bioaccumulation portion of KABAM is 

based upon work by Arnot and Gobas (2004) who parameterized a bioaccumulation 

model based on PCBs and some pesticides (e.g., lindane, DDT) in freshwater aquatic 

ecosystems. KABAM relies on a chemical's octanol-water partition coefficient (KOW) to 

estimate uptake and elimination constants through respiration and diet of organisms in 

different trophic levels. Pesticide tissue residues are calculated for different levels of an 

aquatic food web. The model then uses pesticide tissue concentrations in aquatic animals 

to estimate dose- and dietary-based exposures and associated risks to mammals and birds 

consuming aquatic organisms, using an approach that is similar to the T-REX model 

(USEPA 2008). 

KABAM incorporates 7 trophic levels to describe bioaccumulation of a pesticide in a 

model aquatic food web: phytoplankton, zooplankton (e.g., Daphnia sp.), benthic 

invertebrates (e.g., Chironomus sp., crayfish), filter feeders (e.g., mussels, clams), small 

fish (e.g., young of the year), medium sized fish (e.g., adult bluegill), and larger uppertrophic level fish (e.g., largemouth bass).

Metrafenone concentrations in organisms of the aquatic trophic levels listed above were 

used to estimate acute and chronic exposures of piscivorous mammals and birds 

consuming fish. Applicable and available acute and chronic toxicity data on metrafenone 

(mammals and birds) were used to calculate risk quotients for estimated exposures due to 

bioaccumulation of metrafenone in an aquatic ecosystem. 

b. Terrestrial Exposure Models

T-REX Model

The focus of terrestrial wildlife exposure estimates is for birds (also acting as surrogate 

for reptiles and terrestrial-phase amphibians) and mammals with an exposure route 

emphasis on uptake through the diet. The residues in or on potential dietary sources for 

mammals and birds (e.g., vegetation, insects, and seeds) were estimated using the Tier I 

 

4

PRZM 3.1.2.2 (5/16/05) and EXAMS 2.98.04(4/25/04) were used rather than GENEEC2 (4/25/04) in 

anticipation of toxicity concerns for aquatic organisms. 
Page 28 of 114

model T-REX (Version 1.4.1, 2008). In this Tier I assessment, it was assumed that 

organisms are exposed to one active ingredient in a given exposure scenario. In all 

screening-level assessments, the organisms are assumed to consume 100% of their diet as 

one food type and one food source. The T-REX output is presented in the Risk 

Characterization section of this document as well as an example in Appendix C. 

The approach used to estimate exposure of terrestrial animals to metrafenone was based 

on potential foliar applications of metrafenone. Upper-bound exposure levels were 

calculated for spray applications of metrafenone using maximum proposed application 

rates for one application for the proposed uses. The exposure estimates are based on a 

database of pesticide residues on wildlife food sources associated with specified 

application rates (Kenaga, 1972; Fletcher et al., 1994). Essentially, for a single 

application, there is a linear relationship between the amount of pesticide applied and the 

amount of pesticide residue present on a given food item. Food item residue levels are 

then linearly adjusted based on application rate. The upper-bound estimates are used to 

estimate risks since these values represent the high-end exposure that may be encountered 

for terrestrial species that consume food items that have received label-specified pesticide 

application. Although these represent higher-end estimates, they do not represent the 

highest possible exposure estimates. 

T-REX is a simulation model that, in addition to incorporating the relationship between 

application rate and food item residue concentrations, accounts for pesticide degradation 

in the estimation of terrestrial EECs. T-REX calculates pesticide residues on each type of 

food item on a daily interval for one year. A first-order decay function is used to calculate 

the residue concentration at each day based on the concentrations present from both 

initial and all subsequent applications. The decay rate is dependent on the foliar 

dissipation half-life. The food item concentration on any given day is the sum of all 

residues up to that day, taking into account the first-order degradation. The initial 

application occurs on day 0 (t=0) and the model runs for 365 days. Over the 365-day run, 

the highest residue concentration is the measure of exposure (EEC) used to calculate risk 

quotients (RQs).

The foliar dissipation half-life and residue decline studies can be important in estimating 

exposure because they essentially determine how long the pesticide remains in or on food 

items after application. In many cases, neither empirically determined foliar dissipation 

nor residue decline half-life (with a day 0 residue) values are available, in which case the 

default value of 35 days is used (Willis and McDowell, 1987). That was the case for this 

assessment. 

TERRPLANT Model

The TerrPlant (Ver.1.2.2) model is used to predict EECs from terrestrial uses for 

terrestrial plants located in dry and semi-aquatic areas adjacent to the treated field or 

treated water body. TerrPlant assumes 100% efficiency in ground and aerial applications. 

A semi-aquatic area (wetland) is defined as a low-lying area of terrestrial habitat that is 

wet but may dry up at times throughout the year. TerrPlant incorporates two similar 
Page 29 of 114

conceptual models for depicting dry and semi-aquatic areas of terrestrial habitats. For 

both models, a non-target area is adjacent to the target area. Pesticide exposures to plants 

in the non-target area are estimated to receive runoff and spray drift from the target area. 

For a dry area adjacent to the treatment area, runoff exposure is estimated as sheet runoff. 

Sheet runoff is the amount of pesticide in water that runs off of the soil surface of a target 

area of land which is equal in size to the non-target area (1:1 ratio of areas). In the sheet 

runoff scenario, the treated area generating runoff is assumed to drain into an area with 

equal size containing seedlings, resulting in 1, 2, or 5% of the application rate being 

deposited. For semi-aquatic areas, runoff exposure is estimated as channel runoff. 

Channel runoff is the amount of pesticide that runs off of a target area 10 times the size of 

the non-target area (10:1 ratio of areas). In the channel runoff scenario, a ten-to-one ratio 

of watershed area to receiving area results in 10, 20, or 50% of the application rate being 

deposited on soil with emerging or emerged seedlings. The magnitude of runoff is 

assumed to be dependent on the water solubility of the pesticide active ingredient. For 

pesticides with a solubility of <10, 10 to 100, or >100 ppm, runoff fractions of 0.01, 0.02 

or 0.05 respectively are selected by the model user. 

 

Exposures through runoff and spray drift are then compared to measures of survival and 

growth (e.g. effects to seedling emergence and vegetative vigor) to develop RQ values. 

The model compares the combined deposition estimates from runoff and spray drift to 

adverse effect levels measured in seedling emergence studies. In addition, RQs are 

derived for plants with consideration for spray drift exposures. For monocots and for 

dicots, TerrPlant compares estimated spray drift deposition, without a runoff exposure 

component, to the more sensitive measure of effect, either seedling emergence or 

vegetative vigor (USEPA 2005). 

Table 7 summarizes the measures of ecological effects and exposure used to assess 

ecological risk following exposure to metrafenone with the proposed uses.

Table 7. Measures of Ecological Effects and Exposure for Metrafenone

Assessment Endpoint Surrogate Species and 

Measures of Ecological 

Effect1,2

Measures of Exposure

Birds3Survival Bobwhite Quail acute oral 

LD50, subacute dietary LC50

Mallard Duck acute oral 

LD50, subacute dietary LC50

Upper bound residues on food 

items (foliar)

Reproduction and growth Bobwhite Quail 

reproduction 

NOAEC/LOAEC

Mammals Survival Laboratory rat acute oral 

LD50

Laboratory mouse acute oral 

LD50

Reproduction and growth Laboratory rat reproduction 

NOAEL/LOAEL
Page 30 of 114

Table 7. Measures of Ecological Effects and Exposure for Metrafenone

Assessment Endpoint Surrogate Species and 

Measures of Ecological 

Effect1,2

Measures of Exposure

Freshwater fish4Survival Rainbow trout 96-hr LC50

Bluegill sunfish 96-hr LC50

Peak EEC5

Reproduction and growth Fathead minnow 

NOAEC/LOAEC

60-day average EEC5

Freshwater invertebrates Survival Water flea 48-hr EC50 Peak EEC5

Reproduction and growth No acceptable study 

available

21-day average EEC5

Marine/estuarine fish Survival Sheepshead minnow 96-hr 

LC50

Peak EEC5

Reproduction and growth No study available 60-day average EEC5

Marine/estuarine

invertebrates

Survival Eastern oyster 96-hr EC50

Saltwater mysid 96-hr LC50

Peak EEC5

Reproduction and growth Saltwater mysid 

NOAEC/LOAEC

21-day average EEC5

Terrestrial plants6Survival and growth Monocot Seedling 

emergence 

EC25, NOAEC or EC05

Monocot Vegetative Vigor

EC25, NOAEC or EC05

Dicot Seedling emergence

EC25, NOAEC or EC05

Dicot Vegetative Vigor

EC25, NOAEC or EC05

Estimates of runoff and spray 

drift to non-target areas

Insects Survival Honey bee acute contact 48-

hr LD50

Maximum application rate

Aquatic plants and algae Survival and growth Duckweed 7-day EC50, 

NOAEC

Cyanobacteria 96-hr EC50, 

NOAEC

Marine diatom 96-hr EC50, 

NOAEC

Freshwater diatom 96-hr 

EC50, NOAEC

Green algae 96-hr EC50, 

NOAEC

Algae 72-hr EC50, NOAEC

Green algae 72-hr EC50, 

NOAEC

Peak EEC5

1LD50 = Lethal dose to 50% of the test population; NOAEC = No observed adverse effect concentration; LOAEC = Lowest 

observed adverse effect concentration; LC50 = Lethal concentration to 50% of the test population; EC50/EC25 = Effect 

concentration to 50%/25% of the test population.

2

If species listed in this table represent most commonly encountered species from registrant-submitted studies, risk assessment 

guidance indicates most sensitive species tested within taxonomic group are to be used for baseline risk assessments.

3 Birds represent surrogates for amphibians (terrestrial phase) and reptiles.

4

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

5 One in 10-year return frequency.

6

Four species of two families of monocots - one is corn, six species of at least four dicot families, of which one is soybeans. 
Page 31 of 114

III. Analysis

A. Use Characterization

The proposed end-use product is “Metrafenone 300 SC” (EPA Reg. No. 7969-XXX), a 

suspension concentrate containing 25.2% (3-bromo-6-methoxy-2-methylphenyl)(2,3,4-

trimethoxy-6-methylphenyl)methanone (metrafenone) at a concentration of 2.5 lbs 

metrafenone per gallon. The product is claimed to provide “optimum disease control 

when applied in a regularly scheduled protective fungicide program and when used in a 

spray program that rotates fungicides with different modes of action.” The product is 

intended to control powdery mildew of grapes. 

Ground application is the proposed method of application. The label states, “do not apply

directly to water, to areas where surface water is present, or to intertidal areas below the 

mean high water mark.” The chemical is to be applied at most 6 times per season at a 

maximum application rate of 0.3 lbs a.i./A (Table 5). The label also states, “do not make 

more than 2 sequential applications of Metrafenone 300 SC fungicide before alternating 

to a labeled fungicide with a different mode of action.”

B. Exposure Characterization

1. Environmental Fate and Transport

Summary

Metrafenone is a new chemical of the benzophenone class that is expected to be slightly

mobile. Its major routes of degradation are aqueous photolysis and aquatic metabolism, 

in both aerobic and anaerobic conditions. Soil metabolism is slow, with laboratory halflives of 6 months to a year and accumulation over two years observed in field studies. In 

aquatic environments, the measured photolysis half-life was 6.4 days and metabolism in 

both aerobic and anaerobic occurred with half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to one major 

degradate, CL 377160 [Methanone, (3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy2,4-dimethoxy-6-methylphenyl)-]., and anaerobic aquatic metabolism also led to six other 

major degradates, but all were either unidentified or only tentatively identified. In 

addition, there were many minor degradates, which were formed at low levels 

individually but reached substantial amounts as groups. 

Tier II aquatic exposure modeling was conducted for parent metrafenone and 

metrafenone residues (metrafenone+ extractable residues) (Table 11). This modeling 

approach was used to address uncertainties associated with identification of metrafenone 

residues in soil and sediment. The highest aquatic EECs for metrafenone were 11.70 

μg/L for the daily peak, 8.82 μg/L for the 21 day average, and 6.21 μg/L for the 60 day average. 

The highest aquatic EECs for metrafenone were 20.22 μg/L for the daily peak, 17.67 μg/L 

for the 21 day average, and 16.98 μg/L for the 60 day average.
Page 32 of 114

No monitoring data are available to compare with model estimates. Bioaccumulation 

modeling was conducted because metrafenone has a log octanol:water coefficient > 4. 

Maximum residue concentrations in fish are expected to range from 17,636 to 19,586 

μg/kg-ww. 

Persistence

Metrafenone biodegrades slowly in terrestrial environments. In laboratory studies in a 

variety of soils, aerobic soil metabolism linear half-lives ranged from 178 to 365 days. In 

four of the eight soils tested, data collection extended long enough to determine an 

empirical DT50, of 124 to 188 days in two silt loam soils and 272 to 362 days in a clay

loam and sandy loam soil. In these two soils, metabolism appeared to slow after 272 

days. No data are available for anaerobic soil metabolism rates. Photolysis on soil was 

observed in laboratory studies to occur with a linear half-life of 31 days. 

In aquatic environments, metrafenone biodegrades in weeks to months in both aerobic 

and anaerobic conditions (linear half-lives of 24-27 days and 18-22 days, respectively). 

Considering abiotic degradation, metrafenone is photolyzed in water (half-life of 6.4 

days), but is stable to hydrolysis at pH values from 4 to 9. 

Degradation Products

The only positively identified major degradate of metrafenone was CL 377160 

[Methanone, (3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy-2,4-dimethoxy-6-

methylphenyl)-]. CL 377160 was formed through soil photolysis at up to 18.9% AR and 

through anaerobic aquatic metabolism at up to 10.8% AR in the total system. It was also 

formed as a minor degradate through aquatic photolysis and aerobic aquatic metabolism. 

A compilation of identified degradation products are shown in Appendix A.

In one anaerobic aquatic metabolism study, another six degradates were formed at >9%, 

but these were either unidentified or only tentatively identified. These included TN 

(tentatively identified as a lactone compound; maximum 3.3%, 26.9% and 28.0% in the 

water layer, sediment and total system, respectively), MB (tentatively identified as a 

hydroxylation product of TN; maximum 1.1%, 11.6% and 11.7% in the water layer, 

sediment and total system, respectively), and four unidentified degradates formed in the 

total system at 9.3% to 13% AR. 

Carbon dioxide was also a major degradate, formed through aquatic photolysis at up to 

25% AR and through all other measured processes as a minor degradate.

Most processes also resulted in formation of a substantial amount of minor degradates, 

some individually measured and identified, but most not. Although all of these 

degradates were present at less than 10%, and some at very low levels, they still may be 

of exposure concern because of the large overall amounts. In some cases minor 

degradates, mostly unidentified, make up more than 50% of the applied radioactivity in a 

single sampling event. In addition, based on the structure of the parent compound and 
Page 33 of 114

the proposed degradation pathways, many of the minor degradates may have a high 

degree of structural similarity to each other and/or the parent and so may have cumulative 

effects.

Mobility

Batch equilibrium data on metrafenone suggest that the compound will sorb to organic 

surfaces and would be considered “slightly mobile” according to the FAO classification 

scheme (organic carbon partition coefficients range from 1,073 to 2,792 ml/g-oc). Also 

according to FAO classification, metrafenone’s solubility in water of 0.447 mg/L is 

considered “slightly soluble.” It showed low volatility from soil and water with <0.5% 

volatilization in any laboratory study, consistent with the vapor pressure of 1.15 x 10-6 

mmHg. Therefore, dissipation in the environment is expected to occur predominantly via 

runoff of suspended soil and sediments to which metrafenone is adsorbed. Based on 

terrestrial field dissipation studies in the UK , metrafenone was detected at a soil depth of 

20-30 cm after 2 years.

In aquatic systems, partitioning of metrafenone to sediment occurred rapidly. In one 

anaerobic system, half of the applied metrafenone was detected in sediment on the first 

day, and in three other systems (one anaerobic, two aerobic), at least 50% of the parent 

compound had partitioned to sediment within three to seven days. Including degradates, 

partitioning was rapid in anaerobic systems but slower in aerobic systems. In two 

anaerobic aquatic metabolism studies, more than half of the applied radioactivity (AR) 

was found in sediment within one week and radioactivity in the water layer was down to 

<5% AR in two to six weeks. However, in aerobic aquatic metabolism studies in two 

systems, from 8% to 28% AR remained in the water layer at study termination (100 

days).

Field Dissipation Studies

Field dissipation studies were conducted on bare plots in California (CA), Washington 

(WA), Ontario (ON), and Florida (FL). The first-order dissipation half-life for 

metrafenone in surface soils (0-7.5 cm) was 144 days (DT 50 14-30 days; DT 90 272-360 

days) in CA, 161.2 days (DT 50 181-269 days; DT 90 540-900 days) in WA, 210 days 

(DT 50 59-272 days; DT 90 598-710 days) in ON, and 161 days (DT 50 14-30 days; DT 

90 360-451 days) in FL. No degradation products were detected above the limit of 

quantification (LOQ) in the field dissipation studies.

The reference degradation product in the field study was CL377160. Degradation was not 

a clear route of metrafenone dissipation in field studies because of the lack of detectable 

degradation products in soil. Leaching is possible route of dissipation. There were 

sporadic detections of metrafenone with soil depth in the Florida study with maximum 

detection depth of 15-30 cm, Ontario study with maximum detection depth of 60-75 cm, 

Washington study with a maximum depth depth of 7.5-15 cm, and California study with 
Page 34 of 114

a maximum detection depth of 15-30 cm. The field studies were not designed to assess 

runoff and volatilization of metrafenone residues. 

Bioaccumulation in Fish

Bluegill sunfish exposed to metrafenone, at 5 and 50 μg/L, accumulated metrafenone 

residues during a 28 day accumulation period. After the accumulation phase, the fish 

were transferred to metrafenone-free water for a 14 day depuration phase. For the 

bromophenyl labeled metrafenone, lipid normalized bioconcentration factors (BCFs) 

ranged 140 to 460 in whole fish. For trimethoxybenzene labeled metrafenone, lipid 

normalized bioconcentration factors (BCFs) ranged 490 to 530 in whole fish. The lipid 

normalized BCF range indicates that metrafenone is not expected to accumulate in tissues 

of aquatic organisms. Major bioaccumulated residues (>10% of TRR) were identified as 

[(3-Bromo-6-methoxy-2-methylphenyl)(4-hydroxy-2,3-dimethoxy-6-

ethylphenyl)methanone (CL 434223), CL1500699 (3- bromo-6-methoxy-2-

methylphenyl)[4-(beta-D-gluco pyran uronosyloxy)-2,3-dimethoxy-6-methyphenyl]-

methanone), and CL377160. These degradation products were detected in whole fish, 

viscera, fillet, and in the exposure water. The bioaccumulation rate at 90% steady-state 

of total radioactive residue and metrafenone ranged from 1.3 to 1.8 days and 1.8 to 2.1 

days, respectively. The 95% depuration rate of total radioactive residue and metrafenone 

ranged from 1.8 to 2.3 days and 1.8 to 2.1 days, respectively. 

2. Measures of Aquatic Exposure

a. Aquatic Exposure Modeling

The estimated environmental concentrations (EECs) reported in the assessment were 

calculated using the Tier II model for surface water (PRZM/EXAMS). Sample inputs and 

outputs of the model are presented in Appendix B.

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are screening 

simulation models coupled with the input shell pe5.pl (Aug 2007) to generate daily 

exposures and 1-in-10 year EECs of metrafenone and total metrafenone residues that may

occur in surface water bodies adjacent to application sites receiving metrafenone residues 

through runoff and spray drift for specific scenarios. PRZM simulates pesticide 

application, movement and transformation on an agricultural field and the resultant 

pesticide loadings to a receiving water body via runoff, erosion and spray drift. EXAMS 

simulates the fate of the pesticide and resulting concentrations in the water body. The 

standard scenario used for ecological pesticide assessments assumes application to a 10-

hectare agricultural field that drains into an adjacent 1-hectare water body, 2-meters deep 

(20,000 m3volume) with no outlet. PRZM/EXAMS was used to estimate screening-level 

exposure of aquatic organisms to metrafenone residues. The measure of exposure for 

aquatic species is the 1-in-10 year return peak or rolling mean concentration. The 1-in-10 

year peak is used for estimating acute exposures of direct effects to aquatic organisms as 

well as indirect effects. The 1-in-10-year 60-day mean concentration is used for assessing 

chronic exposure. The 1-in-10 year 21-day mean concentration is used for assessing 
Page 35 of 114

chronic exposures to aquatic invertebrates. 

Input Parameters

The appropriate input parameters were selected from the physical/chemical properties 

and environmental fate data submitted by the petitioner to support registration of 

metrafenone. Input parameters were selected in accordance with US EPA-OPP EFED 

water model parameter selection guidelines, Guidance for Selecting Input Parameters in 

Modeling the Environmental Fate and Transport of Pesticides, Version 2.1, November 

10, 2009. Expanded information about the models, selection of input parameters and 

scenarios can be obtained from http://www.epa.gov /oppefed1/models/water/index.htm. 

The use input parameters were selected from label for the end-use product “Metrafenone 

300 SC.” The physical-chemical properties and environmental fate input parameters 

were obtained from studies submitted and reviewed by the Agency. 

Total Residues Modeling Input Parameters

Calculation of total residue half-lives for metrafenone are based on the concentration 

(expressed as percent of applied radioactivity) of extractable residues (Table 8). 

Extractable residues include metrafenone, CL 377160, tentatively identified compounds, 

and unidentified compounds (Appendix A). 

Table 8. Total Extractable Metrafenone Residue Half-lives from Laboratory Degradation Studies 

Study 

Type

MRID1 Half-life 

(days)

Environmental 

Matrix

Extractable Residues

Aqueous 

Photolysis -23 27 Total Mass Balance - VOC – CO2

Soil 

Photolysis -24 47.8 Acetonitrile, acetonitrile:0.2NHCl, 0.5 N NaOH

Aerobic Soil -27 169.1 sandy loam soil Acetonitrile, acetonitrile:acetone, acetonitrile:water

Aerobic Soil -26 210.0 clay loam soil Acetone, methanol:water

Aerobic Soil -25 277.2 silty loam soil Acetone, methanol :water, acetonitrile:0.5NHCl

Aerobic Soil -27 277.3 clay loam soil Acetonitrile, acetonitrile:acetone, acetonitrile:water

Aerobic Soil -27 301.4 silt loam soil Acetonitrile, acetonitrile:acetone, acetonitrile:water 

Aerobic Soil -26 315.1 sandy loam soil Acetone, methanol:water 

Aerobic Soil -27 330.1 silt loam soil Acetonitrile, acetonitrile:acetone, acetonitrile:water 

Aerobic Soil -26 364.8 loamy sand soil Acetone, methanol:water 

Anaerobic 

Aquatic -29 182.0

DI water- silty 

clay loam

Water + Acetone, methanol acetic acid, acetonitrile, 0.5N 

NaOH:acetonitrile, ammonium hydroxide:acetonitrile

Anaerobic 

Aquatic -31 577.6 pond-sandy loam

Water + acetone:acetonitrile, acetonitrile:formic acid, 

acetonitrile;water formic acid, 

acetonitrile:water:triethylamine, acetonitrile:0.05 M sodium 

phosphate dibasic, 0.5N ammonium hydroxide

Aerobic 

Aquatic -30 91.2 river-loam

Water + acetone, methanol:acetic acid, methylene chloride, 

acetonitrile:0.5N NaOH

Aerobic 

Aquatic -30 123.8 pond-sand Total Mass Balance - VOC – CO2

1- Prefix MRID number is 472674-

Surface water

Scenarios used to run PRZM and EXAMS (Tier II) for the proposed use are shown in 
Page 36 of 114

Table 9. Input parameters for modeling in Tier II are shown in Table 10. 

Table 9. Scenarios used to estimate Metrafenone concentrations in surface water.

Agricultural 

Commodity

Crop Scenario Met File Scenario Characterization

Grapes NY 

CA

W14860.dvf

W93193.dvf

Standard Scenarios for assessing pesticides use on 

grapes

Table 10. PRZM/EXAMS Input Parameters for Metrafenone and Total Extractable Metrafenone 

Residues

PARAMETER Metrafenone Total Extractable 

Metrafenone 

Residues

COMMENT SOURCE

Application Rate per 

Event

Lb a.i./A (kg a.i./ha)

0.3 lb a.i./A 0.3 lb a.i./A

Metrafenone 300 SC 

Label

No. of Applications

(Interval) 6 (14 day) 6 (14 day) Metrafenone 300 SC 

Label

CAM

(Chemical App. 

Method)

2 2 Broadcast spray Metrafenone 300 SC 

Label

Depth of Incorporation 0 0 Default

Spray Drift Fraction / 

Application Efficiency 0.01 / 0.99 0.01 / 0.99 Assume ground spray. EFED Input Guidance

Aerobic Soil 

Metabolism t1/2

303 days 313 days Upper 90th percentile of 

the mean half-life (n=8)

MRID 47267425

MRID 47267426

MRID 47267427

Aerobic Aquatic 

Degradation t1/2 

28.2 days 158 days Upper 90th percentile of 

the mean half-life (n=2) MRID 47267430

Anaerobic Aquatic 

Degradation t1/2

25.3 days 989 days Upper 90th percentile of 

the mean half-life (n=2)

MRID 47267429

MRID 47267431

Aqueous Photolysis 

t1/2

6.4 days 27.0 days Corrected for dark MRID 47267423

Hydrolysis t1/2 0 days 0 days Stable MRID 47267422

Soil Partition 

Coefficient (Koc)

2188 mL/goc 2188 mL/goc Average Koc MRID 47267420

Molecular Weight 409 g/mole 409 g/mole MRID 47267423

Water Solubility @ 

25°C 0.474 mg/L 0.474 mg/L MRID 47267423

Vapor Pressure 1.15 x 10-6 mmHg 1.15 x 10-6 mmHg EPA Fact Sheet 

(9/06)
Page 37 of 114

Tier II- PRZM/EXAMS

Tier II estimated environmental concentrations for metrafenone and total metrafenone residues 

are shown in Table 11. 

Table 11. Estimated Exposure Concentrations for Metrafenone and Total Metrafenone Residues 

from Surface Water. Concentrations are in μg/L (ppb)

Agricultural 

Commodity/Scenario

1-in-10 yr Peak 1-in-10 yr 21-Day 

Average

1-in-10 yr 60-Day 

Average 

Metrafenone

NY Grapes 11.70 8.82 6.21

CA Grapes 1.53 1.10 0.75

Total Metrafenone Residues*

NY Grapes 20.22 17.67 16.98

CA Grapes 2.25 1.89 1.58

*Parent metrafenone + identified and unidentified extractable residues

b. Aquatic Exposure Monitoring and Field Data

Monitoring data for metrafenone in surface water and ground water are not available in 

the United States or Europe.

c. Aquatic Bioaccumulation Assessment

Available data on the octanol-water partition coefficient (Kow) for metrafenone indicates 

that this pesticide may accumulate in aquatic food webs. Because the Log Kow is > 4.0, 

KABAM v.1.0 was used to estimate concentrations of metrafenone in tissues of aquatic 

organisms resulting from bioaccumulation. Input parameters are provided in Table 12

and estimated concentrations of metrafenone in fish are provided in Table 13. Sample 

KABAM output is provided in Appendix D.
Page 38 of 114

Table 12. Input Parameters and Chemical Characteristics of Metrafenone Used in KABAM

Characteristic Value Comments

Log KOW 4.3

KOW 19953

KOC (L/kg OC) 2188 Input value used in PRZM/EXAMS to derive EECs. 

Time to steady state 

(TS; days)

8 This value is calculated automatically from the Log KOW value 

entered above.

Pore water EEC 

(μg/L)

16.8 Value generated by PRZM/EXAMS benthic file for New York 

Grapes scenario for metrafenone total residue and high runoff 

scenario. PRZM/EXAMS EEC represents the freely dissolved 

concentration of the pesticide in the pore water of the sediment. 

The appropriate averaging period of the EEC is dependent on the 

specific pesticide being modeled and is based on the time it takes 

for the chemical to reach steady state. 21-day average concentration

(EEC) was used as averaging period closest to the time to steady 

state calculated above.

Water Column EEC 

(μg/L)

17.7 Value generated by PRZM/EXAMS water column file for New

York Grapes scenario for metrafenone total residue and high 

runoff scenario. PRZM/EXAMS EEC represents the freely 

dissolved concentration of the pesticide in the water column. 21-

day average concentration (EEC) was used as averaging period 

closest to the time to steady state calculated above (as discussed 

above for pore water). 

Table 13. Estimated Concentrations of Metrafenone in Fish (based on metrafenone total residue scenario)

Ecosystem Component Total 

concentration 

(μg/kg-ww)

Lipid 

normalized 

concentration 

(μg/kg-lipid)

Contribution 

due to diet 

(μg/kg-ww)

Contribution 

due to 

respiration 

(μg/kg-ww)

Small Fish 17,636 440909 862.94 16,773.41

Medium Fish 18,305 457626 1,651.07 16,653.98

Large Fish 19,586 489661 3,063.04 16,523.40
Page 39 of 114

3. Measures of Terrestrial Exposure

a. Terrestrial Exposure Modeling

T-REX

Exposure of free-ranging terrestrial animals is a function of the timing and extent of 

pesticide application with respect to the location and behavior of those species. OPP’s 

terrestrial exposure model generates exposure estimates assuming that the animal is 

present on the use site at the time that pesticide levels are highest. The upper-bound 

pesticide residue concentration on food items is calculated from both initial applications 

and any additional applications, taking into account pesticide degradation between 

applications. Although this approach is conservative, it is reasonable, particularly when 

considering acute risks. For acute risks, the assumption is that the duration of exposure is 

a single day and, again, occurs when residue levels are highest. In evaluating chronic 

risks, longer-term exposure estimates are also based on the assumption that the animal is 

present on the use site when residue levels are highest and furthermore that it repeatedly 

forages on the use site.

The current screening-level approach does not directly relate timing of exposure to 

critical or sensitive population, community, or ecosystem processes. Given that the 

application timing and location is crop-dependent, it is difficult to address the temporal 

and spatial co-occurrence of metrafenone use and sensitive ecological processes. 

However, pesticides are frequently used from spring through fall; crop cultivation 

frequently starts in the spring, hence uses of metrafenone are likely to occur in spring and 

perhaps summer depending on the region. Spring and early summer are typically seasons 

of active migrating, feeding, and reproduction for many wildlife species. The increased 

energy demands associated with these activities (as opposed to hibernation, for example) 

can increase the potential for exposure to pesticide-contaminated food items since 

agricultural areas can represent a concentrated source of relatively easily obtained, highenergy food items. In this assessment, the spatial extent of exposure for terrestrial animal 

species is limited to the use area only and the area immediately surrounding the use area.

Currently, the Agency does not require toxicity studies on reptiles and amphibians in 

support of pesticide registrations. To accommodate this data gap, birds are used as 

surrogates for terrestrial-phase amphibians and reptiles. It is assumed that, given the 

usually lower metabolic demands of reptiles and amphibians compared to birds, exposure 

to birds would be greater due to higher relative food consumption. While this assumption 

is likely true, there are no supported relationships regarding the relative toxicity of a 

compound to birds and herpetofauna. The lack of toxicity data on reptiles and amphibians 

represents a source of uncertainty in this assessment.

Tables 14 and 15 list selected predicted EECs for birds, reptiles, terrestrial amphibians, 

and mammals obtained from T-REX simulations for the proposed use of metrafenone at 

the maximum label rates. 
Page 40 of 114

Table 14. Terrestrial Food-Item Residue Estimates for Birds with Metrafenone Proposed Use on 

Grapes at 0.3 lbs a.i./A (6 apps./year; 14 day app. interval) with a Foliar Dissipation Half-life 

default value of 35 Days.

Crop Food Item

Maximum 

Dose-Based 

EECs (mg/kg)1

Maximum

Dose-Based 

EECs (mg/kg)2

Maximum 

Dose-Based 

EECs (mg/kg)3

Dietary-Based EECs

(ppm)

4

Grapes

Short grass 274.49 156.52 70.08 241.01

Tall grass 125.81 71.74 32.12 110.46

Broadleaf plants/ small insects 154.40 88.04 39.42 135.57

Fruits, pods, seeds, lg. insects 17.16 9.78 4.38 15.06

1

Based on 20 gram birds (acute)

2 Based on 100 gram birds (acute)

3 Based on 1000 gram birds (acute)

4 Dietary-based EECs apply to both acute and chronic exposure

Table 15. Terrestrial Food-Item Residue Estimates for Mammals with Metrafenone Proposed Use 

on Grapes at 0.3 lbs a.i./A (6 apps./year; 14 day app. interval) with a Foliar Dissipation Half-life 

default value of 35 Days.

Size Class

(grams)

Adjusted

LD50

1

EECs

Short Grass Tall Grass Broadleaf Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

Granivore

Dose-Based Dose-Based Dose-Based Dose-Based Dose-Based

15 2225.56 229.78 105.32 129.25 14.36 3.19

35 1800.71 158.81 72.79 89.33 9.93 2.21

1000 778.86 36.82 16.88 20.71 2.30 0.51

Dietary-Based EECs2241.01 110.46 135.57 15.06

Not 

applicable

1 Herbivores/ insectivores; Granivores

2 Dietary-based EECs apply to both acute and chronic exposure

TERRPLANT

Effects on non-target terrestrial plants are most likely to occur as a result of spray drift 

and/or runoff from ground applications. These are important factors in characterizing the 

risk of metrafenone to non-target plants, which is assumed to reach off-site soil. The 

TerrPlant (Ver.1.2.2) model predicts EECs for terrestrial plants located in dry and semiaquatic areas adjacent to the treated field. The EECs are based on the application rate 

and solubility of the pesticide in water and drift characteristics. The amount of 

metrafenone that runs off is a proportion of the application rate and is assumed to be 1%, 

based on metrafenone’s solubility of <10 ppm (i.e. 0.474 mg/L) in water. Drift from 

ground applications are assumed to be 1% the application rate. An incorporation depth 

was not referenced in the label setting the default value to 1 inch for ground applications. 

For a standard scenario on an agricultural field, the runoff scenario for terrestrial plants 

inhabiting dry areas adjacent to a field is characterized as “sheet runoff” (one treated acre 

to an adjacent acre; a 1:1 ratio) and inhabiting semi-aquatic or wetland areas adjacent to a 

field is characterized as “channelized runoff” (10 treated acre to an adjacent low-lying 

acre; a 10:1 ratio). The TerrPlant model EECs are presented in Table 16. 
Page 41 of 114

Table 16. Estimated Environmental Concentrations of Metrafenone for Terrestrial Plants from Grape Use

Application 

Method

Application 

Rate (lbs a.i./A)

Total Loading to 

Dry areas (lb/A) 1

Total Loading to Semi-Aquatic 

Areas (lb/A)2 Drift (lb/A)3

Ground 0.3*0.006 0.033 0.003

Ground 1.8** 0.036 0.198 0.018

1 EEC = Sheet Runoff + Drift (1% for ground)

2 EEC = Channelized Runoff + Drift = 1% for ground

3 EEC for ground (appl rate x 1% drift)

* Maximum single application rate

**Maximum seasonal application rate

C. Ecological Effects Characterization

1. Aquatic Effects Characterization

a. Aquatic Animals

(1) Acute Effects

Freshwater Fish and Aquatic-Phase Amphibians -Technical

The freshwater fish studies on rainbow trout (Oncorhynchus mykiss, MRID 47267443) 

and bluegill sunfish (Lepomis macrochirus, MRID 47267442) are classified as 

supplemental for several reasons. The water samples were not centrifuged prior to 

analytical determination. Without centrifugation, the amount of chemical that is freely 

dissolved and bioavailable cannot be determined. Stability of exposure to the dissolved 

form throughout the test is unknown. This is especially a problem as some of the testing 

concentrations were conducted above the water solubility limit of the technical grade 

active ingredient (0.2-0.5 mg a.i./L at 12oC). Therefore, the concentrations are reported as 

mg ‘total’ a.i./L and are not useful for RQ calculations, but can contribute to risk 

description.

Freshwater Fish and Aquatic-Phase Amphibians – Metabolites / Degradates

Similar to freshwater fish studies on the technical, the freshwater fish studies on

degradates of metrafenone on rainbow trout (O. mykiss MRID 47267444, 47267445) are

also classified supplemental. The water solubility limit was not given, and there was no 

report of whether the test solutions were centrifuged prior to analytical determination of 

the test concentrations to ensure that the measured concentrations represent bioavailable 

material. For example, in the latter study (MRID 47267445), undissolved test substance 

(likely the result of exceeding the limit of water solubility of the test material) was noted 

at the bottom of the test vessel in all treatment vessels throughout the definitive test. 

Again, the concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ 

calculations, but can contribute to risk description.

Freshwater Fish and Aquatic-Phase Amphibians -Formulations

Similar to the freshwater fish technical grade and metabolite/degradate studies, the 

freshwater fish study on rainbow trout (O. mykiss MRID 47267605) is also classified as 
Page 42 of 114

supplemental. There was no report of whether the test solutions were centrifuged prior to 

analytical determination. Without centrifugation, the amount of chemical that is freely 

dissolved and bioavailable cannot be determined. Stability of exposure to the dissolved 

form throughout the test is unknown; neither is the water solubility for this formulation 

active ingredient. Again, the concentrations are reported as mg ‘total’ a.i./L and are not 

useful for RQ calculations, but can contribute to risk description.

Table 17. Freshwater Fish Acute Toxicity Data

Common Name %AI Study parameters LC50/NOAEC/LOAEC MRID Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Rainbow trout

Oncorhynchus 

mykiss

97.1 96 hour flowthrough study

2 reps / 10 fish per 

rep.

Mean-measured: 

<0.000498 

(negative, solvent), 

0.065, 0.13, 0.25, 

0.43, and 0.82 mg 

total a.i./L

96-hr LC50 > 0.82 mg total 

a.i./L

NOAEC: 0.25 mg total a.i./L

Endpoint(s) affected: mortality, 

sublethal effects.

Mortality

Cumulative mortality after 96 

hours was 0% among all fish in 

the negative and solvent control 

groups, and in the treatment 

groups exposed to 0.13 and 0.25 

mg a.i./L of AC 375839. 

Cumulative mortality was 5% 

among fish exposed to 0.065, 

0.43 and 0.82 mg a.i./L of AC 

375839 after 96 hours.

Sublethal effects

No sublethal effects were 

observed among fish in the 

negative or solvent controls, 

0.065, 0.13, 0.25 or 0.43 mg 

a.i./L treatment groups exposed 

to AC 375839 after 96 hours. 

Within the 0.82 mg a.i./L 

treatment group, 16% of fish 

still living were lethargic and 

5% exhibited dark discoloration 

after 96 hours.

47267443 Supplemental

(not to be used in 

risk estimation)/

At most, Highly 

toxic1
Page 43 of 114

Table 17. Freshwater Fish Acute Toxicity Data

Common Name %AI Study parameters LC50/NOAEC/LOAEC MRID Classification/

Category

Bluegill sunfish 

Lepomis 

macrochirus

97.1 96 hour flowthrough study

2 reps / 10 fish per 

rep.

Mean-measured: 

<0.000498 

(negative, solvent), 

0.066, 0.14, 0.25, 

0.45, and 0.87 mg 

total a.i./L

96-hr LC50 > 0.87 mg total 

a.i./L

NOAEC: 0.45 mg total a.i./L

Endpoint(s) affected: mortality, 

sublethal effects.

Mortality

Cumulative mortality after 96 

hours was 0% among all fish in 

the negative and solvent control 

groups and all treatment groups 

except the 0.87 mg a.i./L 

treatment group in which 15% 

of fish died.

Sublethal effects

No sublethal effects were 

observed among fish in the 

negative or solvent controls, 

0.066, 0.14, 0.25 or 0.45 mg 

a.i./L treatment groups exposed 

to AC 375839 after 96 hours. 

Within the 0.87 mg a.i./L 

treatment group, 18% of fish 

still living were lethargic and 

12% were lying on the bottom 

of the test chamber with little 

motion other than gill 

movement after 96 hours.

47267442 Supplemental

(not to be used in 

risk estimation)/ 

At most, Highly 

toxic1

Metabolites/ Degradates

Rainbow trout

Oncorhynchus 

mykiss

99.5 Reg. No. 4074484 

(Metabolite of 

BAS 560 F)

96 hour static 

study; limit test

2 reps (neg. 

control), 3 reps 

(treatment) / 10 

fish per rep.

Mean-measured: 

<1 (negative) and 

99 mg total a.i./L

96-hr LC50 > 99 mg total a.i./L

NOAEC ≥ 99 mg total a.i./L

Endpoint(s) affected: none.

47267444 Supplemental

(not to be used in 

risk estimation)/

At most, Slightly 

toxic1
Page 44 of 114

Table 17. Freshwater Fish Acute Toxicity Data

Common Name %AI Study parameters LC50/NOAEC/LOAEC MRID Classification/

Category

Rainbow trout 

Oncorhynchus 

mykiss

98.2 Reg. No. 4084564

(Metabolite of 

BAS 560F)

96 hour static 

study

1 rep / 10 fish per 

rep.

Mean-measured: 

<1 (negative), 4.4, 

9.2, 20.3, 35.2 and 

58.4 mg total a.i./L

96-hr LC50 15.8 (9.2-35.2) mg 

total a.i./L

NOAEC: 9.2 mg total a.i./L

Endpoint(s) affected: mortality, 

sublethal effects

Mortality

Cumulative mortality at 96 

hours was 80% in the 20.3 mg 

total a.i./L concentration and 

100% in the two highest 

concentrations.

Sublethal effects

Tottering and distended 

abdomen were observed after 4 

hours in the group exposed to 

58.4 mg total a.i./L; also 

observed among those in the 

group exposed to 20.3 mg total 

a.i./L between 24 and 72 hours. 

Apathy and distended abdomen 

were observed after 24 hours 

among those in the 35.2 mg 

total a.i./L treatment group and 

after 96 hours among those in 

the group exposed to 20.3 mg 

total a.i./L.

47267445 Supplemental 

(not to be used in 

risk estimation)/

Slightly toxic1

Formulations

Rainbow trout

Oncorhynchus 

mykiss

24.7% 

a.i.; 

294 g 

BAS 

560 

00F/L

BAS 560 00F (SF 

10358, RLF 

12359) 

96 hour static 

study

2 reps. / 10 fish per 

rep.

Mean-measured: 

<4.05 (neg. 

control), 12, 20, 

34, 56, and 94 mg 

form/L [<1 (neg. 

control), 3.0, 4.9, 

8.3, 13.7, and 23.3 

mg total a.i./L]

96-hr LC50 >94 mg form/L 

[>23.3 mg total a.i./L]

NOAEC ≥ 94 mg form/L [23.3 

mg total a.i./L]

Endpoint(s) affected: none. 

47267605 Supplemental

(not to be used in 

risk estimation)/ 

At most, Slightly 

toxic1

1Based on LC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 

practically nontoxic
Page 45 of 114

Freshwater Invertebrates -Technical

The freshwater invertebrate study using the technical grade active ingredient on water 

flea (Daphnia magna, MRID 47267437) is classified as supplemental. The water samples 

were not centrifuged prior to analytical determination. Without centrifugation, the 

amount of chemical that is freely dissolved and bioavailable cannot be determined. 

Stability of exposure to the dissolved form throughout the test is unknown. This is 

especially a problem as some of the testing concentrations were conducted at or above the 

water solubility limit of the technical grade active ingredient (0.2-0.5 mg a.i./L at 12oC). 

Therefore, the concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ 

calculations, but can contribute to risk description.

Freshwater Invertebrates –Metabolites / Degradates

Similar to freshwater invertebrate study on the technical, the freshwater invertebrate 

studies on degradates of metrafenone on the water flea (D. magna MRID 47267438, 

47267439) is also classified supplemental. The water solubility limit was not given, and 

there was no report of whether the test solutions were centrifuged prior to analytical 

determination of the test concentrations to ensure that the measured concentrations 

represent bioavailable material. Again, the concentrations are reported as mg ‘total’ 

a.i./L and are not useful for RQ calculations, but can contribute to risk description.

Freshwater Invertebrates –Formulations

Similar to the freshwater invertebrate technical grade and metabolite/degradate studies, 

the freshwater invertebrate study on water flea (D. magna MRID 47267604) is also 

classified as supplemental. There was no report of whether the test solutions were 

centrifuged prior to analytical determination. Without centrifugation, the amount of 

chemical that is freely dissolved and bioavailable cannot be determined. Stability of 

exposure to the dissolved form throughout the test is unknown; neither is the water 

solubility for this formulation active ingredient. Again, the concentrations are reported as 

mg ‘total’ a.i./L and are not useful for RQ calculations, but can contribute to risk 

description.
Page 46 of 114

Table 18. Freshwater Invertebrate Acute Toxicity Data

Common 

Name

%AI Study parameters EC50/NOAEC/LOAEC MRID Classification

/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Water flea

Daphnia 

magna

97.1 48 hour static study

2 reps.; 10 inverts. per rep

Mean-measured: 

<0.000498 (negative, 

solvent), 0.059, 0.12, 

0.22, 0.45, and 0.92 mg 

total a.i./L 

48-hr EC50 > 0.92 mg total a.i./L

Slope: N/A

NOAEC ≥ 0.92 mg total a.i./L

Endpoint(s) affected: none. 

47267437 Supplemental

(not to be used 

in risk 

estimation)/

At most, 

Highly toxic1

Metabolites/ Degradates

Water flea

Daphnia 

magna

99.5 CL 375816

48 hour static study

4 reps.; 5 inverts per rep.

Mean-measured: <1 

(negative), 12.9, 25.8, 

51.4, and 102.5 mg total 

a.i./L

48-hr EC50 > 102.5 mg total a.i./L 

Slope: N/A

NOAEC ≥ 102.5 mg total a.i./L

Endpoint(s) affected: none. 

47267438 Supplemental

(not to be used 

in risk 

estimation)/ 

Practically 

non-toxic1

Water flea

Daphnia 

magna

98.2 CL 4084564

48 hour static study

4 reps.; 5 inverts per rep.

Mean-measured: <1 

(negative), 6.4, 12.5, 

23.2, 49.6, 66.4 mg a.i./L

48-hr EC50 = 50.9 (42.1-63.5) mg 

total a.i./L

Slope: 4.59 (2.52-6.66)

NOAEC = 23.2 mg total a.i./L

Endpoint(s) affected: immobility.

Immobility

Cumulative immobility was 0% 

among all daphnids exposed to 0 

(negative control), 6.4 and 12.5 

mg total a.i./L of CL 4084564 

(Metabolite of BAS 560 F) after 

48 hours. Cumulative immobility 

was 5% among animals exposed to 

23.2 mg total a.i./L, 55% among 

daphnids exposed to 49.6 mg total

a.i./L and 65% among animals 

exposed to 66.4 mg total a.i./L of 

CL 4084564 (Metabolite of BAS 

560 F) after 48 hours.

 

47267439 Supplemental

(not to be used 

in risk 

estimation)/ 

Slightly toxic1
Page 47 of 114

Table 18. Freshwater Invertebrate Acute Toxicity Data

Common 

Name

%AI Study parameters EC50/NOAEC/LOAEC MRID Classification

/

Category

Formulations

Water flea 

Daphnia 

magna

24.7% 

a.i.; 294 

g BAS 

560 00 

F/L

BAS 560 00 F (SF 10358, 

RLF 12359) 

48 hour static study

2 reps.; 10 inverts per rep. 

Mean-measured: <0.810 

(neg. control), 1.7, 3.1, 

6.1, 12.2, 24.3, and 47.1 

mg form/L [<0.20 (neg. 

control), 0.42, 0.76, 1.5, 

3.0, 6.0, and 11.6 mg total 

a.i./L]

48-hr EC50: 17.1 (12.8-24.3) mg 

form/L [4.2 (3.2-6.0) mg total 

a.i./L]

NOAEC: 6.1 mg form/L [1.5 mg 

total a.i./L]

Endpoint(s) affected: mortality and 

sublethal effects (immobility)

Mortality

Cumulative mortality after 48 

hours was 0% among animals 

exposed to mean-measured 

concentrations of 0 (negative 

control), 1.7, 3.1, 6.1 and 12.2 mg 

form/L. Cumulative mortality was 

65% among animals exposed to 

24.3 mg form/L and 90% among 

animals exposed to 47.1 mg 

form/L after 48 hours.

Immobility

Cumulative immobility aft 48 

hours was 0% at mean-measured 

concentrations of 1.7 and 47.1 mg 

form/L; 5% at neg. control, 3.1, 

and 6.1 mg form/L; 15% at 12.2 

mg form/L; and, 25% at 24.3 mg 

form/L. 

47267604 Supplemental 

(not to be used 

in risk 

estimation) / 

Moderately 

toxic1

1Based on EC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 

practically nontoxic

Marine/Estuarine Fish

Unlike the majority of the aquatic studies, which were supplemental on account of not 

having centrifuged samples which clearly exceeded the water solubility limit, the 

marine/estuarine fish study on the sheepshead minnow (Cyprinodon variegatus, MRID 

47267446) is acceptable on account of having centrifuged the two highest concentrations, 

both of which were above the solubility limit of 0.3 mg a.i./L (in saltwater). The results 

reveal no effects on mortality or sublethal effects.
Page 48 of 114

Table 19. Marine/ Estuarine Fish Acute Toxicity Data 

Common Name %AI Study parameters LC50/NOAEC/LOAEC MRID Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Sheepshead 

Minnow

Cyprinodon 

variegatus

94.2 96 hour flow-through 

study

2 reps / 10 fish per 

rep.

Mean-measured: 

<0.04 (negative, 

solvent), 0.072, 0.13, 

0.24, 0.32 (0.13 mg 

a.i./L based on 

centrifuged samples) 

and 0.65 (0.35 mg 

a.i./L based on 

centrifuged samples) 

mg a.i./L

96-hr LC50 > 0.35 mg dissolved 

a.i./L

NOAEC ≥ 0.35 mg dissolved 

a.i./L

Endpoint(s) affected: none.

47267446 Acceptable/

At most, Highly 

toxic1

1Based on LC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 

practically nontoxic

Marine/Estuarine Invertebrates – Technical

The marine/estuarine invertebrate study using the technical grade active ingredient on 

eastern oyster (Crassostrea virginica, MRID 47267440) is classified as supplemental. 

Given that centrifugation was not performed on all concentration test levels, it is possible 

that the endpoint retrieved from this study will provide an underestimation of risk. For 

example, we know that after centrifugation of the highest test level the mean-measured 

concentration decreased by 42% relative to the pre-centrifugation mean-measured 

concentration. The reduction in soluble substance is likely due to the concentration being 

above the limit of solubility (i.e., 0.3 mg a.i./L). Nevertheless, it is unknown from the 

study results whether a similar reduction will occur at lower concentrations, including 

one more above the limit of solubility and the three levels remaining below the limit of 

solubility. Similarly, the saltwater mysid study (Americamysis bahia, MRID 47267441) 

is classified supplemental on account of no centrifugation of water samples at any test 

concentration level prior to analytical determination. Without centrifugation, the amount 

of chemical that is freely dissolved and bioavailable cannot be determined. Stability of 

exposure to the dissolved form throughout the test is unknown. Therefore, the 

concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ calculations, but 

can contribute to risk description.
Page 49 of 114

Table 20. Marine/ Estuarine Invertebrate Acute Toxicity Data

Common 

Name

%AI Study parameters EC50/LC50/NOAEC/LOAEC MRID Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Eastern oyster 

Crassostrea 

virginica

94.2 96 hour flow-through 

study

20 bivalves per level

Time-weighted 

average: <0.04 

(negative, solvent), 

0.0522, 0.104, 0.203, 

0.287, and 0.573 mg 

total a.i./L (highest 

concentration 

centrifuged yielded 

0.33 mg dissolved 

a.i./L)

96-hr EC50: 0.22 (0.20-0.25) mg

total a.i./L2

NOAEC: 0.0522 mg total a.i./L

Endpoint(s) affected: shell 

deposition. 

Shell deposition

Relative to the negative control, 

the mean percent reduction in 

shell growth starting with the 

negative solvent is as follows: 

17.4, 13.9, 26.3, 44.3, 84.2, and 

100%, respectively. No 

significant differences (p= 0.05) 

were detected between the two 

controls.

47267440 Supplemental

(not to be used in 

risk estimation)/

Highly toxic1

Saltwater 

mysid 

Americamysis 

bahia

94.2 96 hour flow-through 

study

2 reps./ 10 mysids 

per rep.

Time-weighted 

average: <0.04 

(negative, solvent), 

0.0749, 0.129, 0.240, 

0.416, and 0.663 mg 

total a.i./L

96-hr LC50: 0.487 (0.428-0.575) 

mg total a.i./L2

NOAEC: 0.0749 mg total a.i./L

Endpoint(s) affected: mortality, 

sublethal effects.

Mortality

At 96 hours, cumulative mortality 

at the TWA concentrations 0.129 

and 0.240 mg total a.i./L was 5%, 

at 0.416 mg total a.i./L was 15%, 

and at 0.663 mg total a.i./L was 

95%.

Sublethal effects

No sub-lethal effects were 

observed in the controls or TWA 

0.0749-0.240 mg total ai/L 

treatment levels. At test 

termination 7 out of the surviving 

17 mysids in the 0.416 mg total

ai/L level and the single surviving 

mysid at the 0.663 mg total ai/L 

level were observed swimming 

erratically.

47267441 Supplemental

(not to be used in 

risk estimation)/ 

Highly toxic1

1Based on EC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 

practically nontoxic

2 Range is 95% confidence interval for endpoint
Page 50 of 114

(2) Chronic Effects

Freshwater Fish – Technical

The freshwater fish study on fathead minnow (Pimephales promelas, MRID 47267449) is 

classified as supplemental. The solubility limit of the test compound is not reported; it is 

possible given previous reports that the limit was approximately 0.2-0.5 mg a.i./L at 12 

oC, which implies that the two highest test concentrations (0.421 and 0.839 mg total 

a.i./L) potentially exceeded the solubility limit and yet centrifugation (or filtration) was 

not mentioned as part of the protocol prior to analytical determination. Without 

centrifugation, the amount of chemical that is freely dissolved and bioavailable cannot be 

determined. Stability of exposure to the dissolved form throughout the test is unknown. 

Therefore, the concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ 

calculations, but can contribute to risk description.

Hatching occurred at all levels on Day 4, and hatching success averaged 88-94% for all 

levels, with no statistically significant differences observed. Post-hatch survival (28-days 

post-hatch) was statistically-reduced compared to the negative control at the 227, 421, 

and 839 μg total a.i./L levels (p≤0.05). Post-hatch survival averaged 96% at the negative 

control through 118 μg total a.i./L levels, and 87, 86, and 11% at the 227, 421, and 839 

μg total ai/L levels, respectively. No clinical signs of toxicity were observed during the 

study in any treatment group. Fish length was significantly reduced relative to the 

average negative control length at levels above 421 μg total ai/L and wet and dry weight 

were significantly lower than the negative control weights at the 839 μg total ai/L level; 

however, significant impact on survival occurred at these levels.

Table 21. Freshwater Fish Chronic Toxicity Data 

Common Name %AI Study parameters NOAEC/LOAEC MRID Classification

/Category

Technical AC 375839 (a.k.a. BAS 560F)

Fathead minnow

Pimephales 

promelas

97.1 32-day flow-through 

test

80 embryos per level, 

split into 20 embryos 

per cup, 1 cup per 

aquarium, 4 rep. 

aquaria per treatment

Time-weighted 

average: <0.498 

(negative, solvent), 57, 

118, 227, 421, and 839 

μg total a.i./L

NOAEC: 0.118 mg total a.i./L

LOAEC: 0.227 mg total a.i./L

Most sensitive endpoint: posthatch survival

Endpoint(s) affected: post-hatch 

survival and growth (total length, 

wet and dry weight)

47267449 Supplemental 

(not to be used 

in risk 

estimation)
Page 51 of 114

Freshwater Invertebrates – Technical

A chronic freshwater invertebrate study (MRID 47267447) with metrafenone technical 

(97.1%) was deemed invalid due to instability of the chemical under test conditions. A 

non-guideline chronic midge study (Chironomus riparius, MRID 47267501) with 

metrafenone technical (97.1%) is also invalid on the basis of low negative control 

emergence.

Marine/Estuarine Fish

No chronic marine/estuarine fish studies were submitted for review.

Marine/Estuarine Invertebrates- Technical

The marine/estuarine invertebrate study on saltwater mysid (Americamysis bahia, MRID 

47267448) is classified as acceptable. Although the solubility limit of the test compound 

is not reported; it is possible given previous reports that the limit was approximately 0.2-

0.5 mg a.i./L at 12 oC. The mean-measured test concentrations of the total metrafenone 

present do not exceed the suggested solubility limit. In addition, the highest nominal 

concentration (0.05 mg a.i./L) is significantly below solubility (i.e., ≥ 4 - 10 times); in 

this particular case, not centrifuging is considered to not affect acceptability of the study.

Finally, given the dilution system design, where the stock solution was a solvent stock 

solution suggests that solubility of the compound is not an issue in this particular case.

The day of first brood release was not assessed. The number of offspring per surviving 

female was statistically-reduced compared to the negative control at the 45 μg ai/L level 

(1.4 versus 5.8 offspring/female). Similarly, the number of offspring per female per 

reproductive day was statistically-reduced compared to the negative control at the 45 μg 

ai/L (0.10 versus 0.44 offspring/female/day). Although not statistically-compared, the 

percentage of females producing young averaged ≥85% at the control through 22 μg ai/L 

treatment levels, but only 25% at the 45 μg ai/L level. The NOAEC for reproduction was 

reported to be 22 μg ai/L. 
Page 52 of 114

Table 22. Marine/ Estuarine Invertebrate Chronic Toxicity Data 

Common Name %AI Study parameters NOAEC/LOAEC MRID Classification

/Category

Technical AC 375839 (a.k.a. BAS 560F)

Saltwater mysid 

Americamysis 

bahia

94.2 28-day flow-through 

test

Before pairing: 60 

mysids per level

After pairing: 20 

mysids per level

Time-weighted 

average: <LOD 

(negative, solvent), 2.8, 

6.2, 12, 22, and 44 μg

total a.i./L

NOAEC: 0.022 mg a.i./L1

LOAEC: 0.044 mg a.i./L

Most sensitive endpoint: 

reproduction (number of 

offspring/female/repro. day)

Endpoint(s) affected: reproduction 

(number of offspring/female/repro. 

day)

47267448 Acceptable

1 Bold value is the value that will be used to calculate risk quotients

b. Aquatic Plants

Vascular Aquatic Plants

The vascular aquatic plant study (MRID 47267511) on duckweed (Lemna gibba) is 

classified as supplemental for several reasons, which are considered major guideline 

deviations. The test was conducted for 7 days instead of the guideline prescribed 14 days. 

More importantly, the dissolved or soluble concentrations (i.e., post-centrifugation) of 

test material were not determined. As a result of the latter, the stability of exposure to the 

dissolved form throughout the test is unknown. This is especially a problem as some of 

the testing concentrations were conducted above the solubility limit of the technical grade 

active ingredient (0.457 mg/L in water; 0.3 mg/L in 20X AAP media both at pH9). 

Therefore, the concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ 

calculations, but can contribute to risk description.

Non-vascular Aquatic Plants - Technical

The non-vascular aquatic plant studies on cyanobacteria (Anabaena flos-aquae; MRID 

47267512), marine diatom (Skeletonema costatum, MRID 47267513), freshwater diatom 

(Navicula pelliculosa, MRID 47267514), and green algae (Pseudokirchneriella 

subcapitata, MRID 47267515) are classified as supplemental for several reasons. The 

water samples were not centrifuged prior to analytical determination. Without 

centrifugation, the amount of chemical that is freely dissolved and bioavailable cannot be 

determined. Stability of exposure to the dissolved form throughout the test is unknown. 

This is especially a problem as some of the testing concentrations were conducted above 

the solubility limit of the technical grade active ingredient (0.457 mg/L in freshwater; 0.3 

mg/L in saltwater). Therefore, the concentrations are reported as mg ‘total’ a.i./L and are 

not useful for RQ calculations, but can contribute to risk description.
Page 53 of 114

Non-vascular Aquatic Plants – Metabolites / Degradates

Similar to the non-vascular aquatic plant technical grade studies, the non-vascular aquatic 

plant studies on the degradates are classified as supplemental for several important 

reasons. For example, the algae study (Pseudokirchneriella subcapitata MRID 

47267516) did not report daily observations of test solution appearance, metabolite water 

solubility, and method of filtration of test solution, which leads to uncertainty in the 

measured concentrations as well as the relationship of mean-measured and nominal 

concentrations relative to the metabolite water solubility value. For this reason too, the 

concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ calculations, but 

can contribute to risk description. In addition, the other algae study (Pseudokirchneriella 

subcapitata MRID 47267517) did not centrifuge the water samples prior to analytical 

determination. Without centrifugation, the amount of chemical that is freely dissolved 

and bioavailable cannot be determined. Stability of exposure to the dissolved form 

throughout the test is unknown; neither is the metabolite water solubility. Again, the 

concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ calculations, but 

can contribute to risk description.

Non-vascular Aquatic Plants - Formulations

Similar to the non-vascular aquatic technical grade and metabolite/degradate studies, the 

non-vascular aquatic plant study on the green algae (Pseudokirchneriella subcapitata) is 

also classified as supplemental. Although centrifugation was conducted on the water 

samples in this particular case the protocol states that it was used to remove algal cells, 

which suggests that the centrifugation method may not have removed the undissolved 

material. Without centrifugation, the amount of chemical that is freely dissolved and 

bioavailable cannot be determined. Stability of exposure to the dissolved form throughout 

the test is unknown; neither is the water solubility for this formulation active ingredient. 

Again, the concentrations are reported as mg ‘total’ a.i./L and are not useful for RQ 

calculations, but can contribute to risk description.
Page 54 of 114

Table 23. Aquatic Plant Toxicity Data

Species %A.I. Study Parameters EC50/NOAEC MRID 

No.

Study 

Classification

Technical AC 375839 (a.k.a. BAS 560F)

Vascular Aquatic Plants

Duckweed 

Lemna gibba

94.2 Tier II study

7 day static renewal study

3 reps. / 4 plants per rep.

Mean measured: <0.04 

(negative, solvent), 0.057, 

0.10, 0.21, 0.41, and 0.76 

mg a.i./L

Biomass (dry weight)

EC50 > 0.76 mg total a.i./L

NOAEC: 0.21 mg total 

a.i./L

Frond density

EC50 > 0.76 mg total a.i./L

NOAEC: 0.41 mg total 

a.i./L

Growth rate

EC50 > 0.76 mg total a.i./L

NOAEC: 0.41 mg total 

a.i./L

Most sensitive endpoint: 

biomass based on NOAEC

Endpoint(s) affected: 

biomass, frond density, 

growth rate

47267511 Supplemental 

(do not use in 

risk 

estimation)

Non-Vascular Aquatic Plants

Cyanobacteria (bluegreen algae)

Anabaena flos-aquae

94.2 Tier II study

96 hour static study

3 reps.

Initial measured: <0.04 

(negative, solvent), 

0.0883, 0.139, 0.217, 

0.580, and 0.862 mg a.i./L

Biomass (area under growth 

curve), cell density, growth 

rate

EC50 > 0.862 mg total a.i./L

NOAEC ≥ 0.862 mg total 

a.i./L

Endpoint(s) affected: none.

47267512 Supplemental 

(do not use in 

risk 

estimation)
Page 55 of 114

Table 23. Aquatic Plant Toxicity Data

Species %A.I. Study Parameters EC50/NOAEC MRID 

No.

Study 

Classification

Marine Diatom

Skeletonema 

costatum

94.2 Tier II study

96 hour static study

3 reps.

Initial measured: <0.04 

(negative, solvent), 

0.0509, 0.109, 0.214, 

0.272, and 0.680 mg a.i./L

Biomass (area under growth 

curve)

EC50: 0.57 (0.38-0.85) mg 

total a.i./L

NOAEC: 0.0509 mg total 

a.i./L

Cell density

EC50 > 0.680 mg total a.i./L

NOAEC: 0.272 mg total 

a.i./L

Growth rate

EC50 > 0.680 mg total a.i./L

NOAEC: 0.272 mg total

a.i./L

Most sensitive endpoint: 

biomass

Endpoint(s) affected: 

biomass, cell density, 

growth rate

47267513 Supplemental 

(do not use in 

risk 

estimation)

Freshwater Diatom

Navicula pelliculosa

94.2 Tier II study

96 hour static study

4 reps.

Initial measured: <0.04 

(negative, solvent), 

0.0761, 0.154, 0.276, 

0.432, and 0.914 mg a.i./L

Biomass (area under growth 

curve)

EC50 > 0.914 mg total a.i./L

NOAEC: 0.432 mg total 

a.i./L

Cell density

EC50 > 0.914 mg total a.i./L

NOAEC: ≥0.914 mg total 

a.i./L

Growth rate

EC50 > 0.914 mg total a.i./L

NOAEC: ≥0.914 mg total 

a.i./L

Endpoint(s) affected: 

biomass based on NOAEC

47267514 Supplemental 

(do not use in 

risk 

estimation)
Page 56 of 114

Table 23. Aquatic Plant Toxicity Data

Species %A.I. Study Parameters EC50/NOAEC MRID 

No.

Study 

Classification

Green Algae

Pseudokirchneriella 

subcapitata

97.1 Tier I study

72 hour static study

6 reps. (negative, solvent 

controls); 3 reps. 

(treatments)

Mean-measured: <0.498 

(negative, solvent), 60, 

123, 232, 472, and 870 g 

a.i./L

Biomass (area under growth 

curve)

EC50: 0.71 (0.65-0.77) mg 

total a.i./L

NOAEC: 0.23 mg total

a.i./L

Cell density

EC50: 0.74 (0.67-0.82) mg 

total a.i./L

NOAEC: 0.23 mg total

a.i./L

Growth rate

EC50 > 0.87 mg total a.i./L

NOAEC: 0.23 mg total

a.i./L

Most sensitive endpoint: 

biomass

Endpoint(s) affected: 

biomass, cell density, 

growth rate

47267515 Supplemental 

(do not use in 

risk 

estimation)

Metabolites/ Degradates

Non-Vascular Aquatic Plants

Algae 

Pseudokirchneriella 

subcapitata

99.5 CL 375816 (Metabolite of 

BAS 560 F)

Tier I study

72 hour static study

5 reps. (negative control); 

3 reps. (treatments)

Mean-measured: ND 

(negative), 6.50, 12.66, 

25.80, 51.45, and 101.92 

mg a.i./L

Biomass (area under growth 

curve), Chlorophyll-a, and 

Growth rate

EC50 > 101.9 mg total a.i./L

NOAEC ≥ 101.9 mg total 

a.i./L

Endpoint(s) affected: none.

47267516 Supplemental 

(do not use in 

risk 

estimation)
Page 57 of 114

Table 23. Aquatic Plant Toxicity Data

Species %A.I. Study Parameters EC50/NOAEC MRID 

No.

Study 

Classification

Algae

Pseudokirchneriella 

subcapitata

98.2 CL 4084564 (Metabolite 

of BAS 560 F)

Tier I study

72 hour static study

5 reps. (negative control); 

3 reps. (treatments)

Mean-measured: ND 

(negative), 3.21, 6.28, 9.9, 

18.57, 38.78, and 58.03

mg a.i./L

Chlorophyll-a

EC50: 24 (21-27) mg total

a.i./L

NOAEC: 9.9 mg total a.i./L

Biomass (area under growth 

curve)

EC50: 26 (22-30) mg total 

a.i./L

NOAEC: 9.9 mg total a.i./L

Growth rate

EC50: 44 (40-47) mg total 

a.i./L

NOAEC: 9.9 mg total a.i./L

Most sensitive endpoint: 

chlorophyll-a

Endpoint(s) affected: 

chlorophyll-a, biomass, and 

growth rate

47267517 Supplemental 

(do not use in 

risk 

estimation)

Formulations

Non-Vascular Aquatic Plants

Green Algae 

Pseudokirchneriella 

subcapitata

24.7 BAS 560 00F (SF 10358, 

RLF 12359)

Tier I study

72 hour static study

6 reps. (negative control); 

3 reps. (treatments)

Initial mean-measured: 

<0.05 (negative), 0.188, 

0.371, 0.716, 1.383, 

2.717, and 5.681 mg a.i./L

Cell density

EC50: 0.66 (0.47-0.91) mg 

total a.i./L

NOAEC: 0.188 mg total 

a.i./L

Biomass (area under growth 

curve)

EC50: 0.73 (0.53-0.99) mg 

total a.i./L

NOAEC: 0.188 mg total 

a.i./L

Growth rate

EC50: 5.2 (4.4-6.2) mg total 

a.i./L

NOAEC: 0.188 mg total 

a.i./L

Most sensitive endpoint: 

cell density

Endpoint(s) affected: cell 

density, biomass, growth 

rate

47267607 Supplemental 

(do not use in 

risk 

estimation)
Page 58 of 114

2. Terrestrial Effects Characterization

a. Terrestrial Animals

(1) Acute Effects

Birds – Technical

The acute avian oral studies (MRID 47267502, 47267503) on 23-week old Northern 

bobwhite quail (Colinus virginianus) and 20-week old mallard duck (Anas 

platyrhynchos), respectively, assessed over 14 days are classified as acceptable. AC 

375839 Technical was administered to the birds via gelatin capsules at nominal levels of 

0 (vehicle control), 400, 600, 900, 1350, and 2025 mg ai/kg bw (limit dose). The 14-day 

acute oral LD50 was >2025 mg ai/kg bw (>limit dose). The 14-day NOAEL was 2025 

mg ai/kg bw, as there were no mortalities, clinical signs of toxicity, or treatment-related 

effects on body weight or food consumption during the 14-day study. In addition, no 

toxicological effects were observed at necropsy. AC 375839 Technical (metrafenone) 

would be classified as practically non-toxic to young adult Northern bobwhite quail (C. 

virginianus) as well as to young adult mallard duck (A. platyrhynchos) in accordance 

with the classification system of the U.S. EPA. 

The acute avian dietary studies (MRID 47267504, 47267505) on 11-day old Northern 

bobwhite quail (C. virginianus) and 9-day old mallard duck (A. platyrhynchos), 

respectively, assessed over 8 days are classified as acceptable. AC 375839 Technical was 

administered to the birds in the diet at nominal concentrations of 0 (negative control), 

100, 270, 729, 1968, and 5314 mg ai/kg diet (adjusted for purity). Mean-measured 

concentrations were <3.6 (<LOD, control), 98, 262, 809, 2130, and 6070 mg ai/kg diet, 

respectively. The 8-day acute dietary LC50 was >6070 mg ai/kg diet. Given there was no 

dose-response, the NOAEC was the highest concentration tested, 6070 mg a.i./kg diet. 

There were no treatment-related mortalities, clinical signs of toxicity, or effects on food 

consumption. Some gross pathological changes were observed. AC 375839 Technical 

(metrafenone) would be classified as practically non-toxic to juvenile bobwhite quail (C. 

virginianus) as well as to juvenile mallard duck (A. platyrhynchos) on an acute dietary 

basis, in accordance with the classification system of the U.S. EPA.

Table 24. Avian Acute Toxicity Data

Common Name %AI Study parameters LD50/LC50 NOAEL/

LOAEL

MRID Classification

/Category

Technical AC 375839 (a.k.a. BAS 560F)

Northern 

Bobwhite Quail 

Colinus 

virginianus

95.86 Acute oral study

5 birds/sex/dose level

14 day observation period

Nominal: 0 (vehicle), 400, 

600, 900, 1350, and 2025 mg 

a.i./kg bw 

LD50 > 2025 mg a.i./kg bw

NOAEL: 2025 mg/kg bw

Probit slope: N/A

Endpoint(s) affected: none.

47267502 Acceptable/

Practically 

non-toxic1
Page 59 of 114

Table 24. Avian Acute Toxicity Data

Common Name %AI Study parameters LD50/LC50 NOAEL/

LOAEL

MRID Classification

/Category

Mallard Duck

Anas 

platyrhynchos

95.86 Acute oral study

5 birds/sex/dose level

14 day observation period

Nominal: 0 (vehicle), 400, 

600, 900, 1350, and 2025 mg 

a.i./kg bw 

LD50 >2025 mg a.i/kg bw

NOAEL: 2025 mg a.i./kg bw

Probit slope: N/A

Endpoint(s) affected: none.

47267503 Acceptable/

Practically 

non-toxic1

Northern 

Bobwhite Quail 

Colinus 

virginianus

95.86 Acute dietary study

12 birds per rep.(neg. control 

& treatment); 3 reps. (neg. 

control), 1 rep. per treatment

5 days on treatment, 3 

additional days observation

Mean-measured: <3.6 (neg. 

control), 98, 262, 809, 2130, 

and 6070 mg a.i./kg diet

LC50 >6070 mg a.i./kg diet

NOAEC: 6070 mg a.i./kg diet

LOAEC >6070 mg a.i./kg 

diet

Issues3: body weight change 

(significant reduction in body 

weight gain (39%, relative to 

Control 1) at the 262 mg 

ai/kg diet level). However, no 

concentration-response was 

observed so it may not be 

biologically significant.

47267504 Acceptable/

Practically 

non-toxic2

Mallard Duck

Anas 

platyrhynchos

95.86 Acute dietary study

12 birds per rep.(neg. control 

& treatment); 3 reps. (neg. 

control), 1 rep. per treatment

5 days on treatment, 3 

additional days observation

Mean-measured: <3.6 (neg. 

control), 98, 262, 809, 2130, 

and 6070 mg a.i./kg diet

LC50 > 6070 mg a.i./kg diet

NOAEC: 6070 mg a.i./kg 

diet

LOAEC >6070 mg a.i./kg 

diet

Issues3: body weight change 

(significant reduction in body 

weight gain (19%, relative to 

controls) at the 262 mg ai/kg 

diet level). However, no 

concentration-response was 

observed so it may not be 

biologically significant.

47267505 Acceptable/

Practically 

non-toxic2

1 Based on LD50 (mg/kg) <10 very highly toxic; 10-50 highly toxic; 51-500 moderately toxic; 501-2000 slightly toxic; >2000 

practically nontoxic

2 Based on LC50 (mg/kg) <50 very highly toxic; 50-500 highly toxic; 501-1000 moderately toxic; 1001-5000 slightly toxic; 

>5000 practically nontoxic

3 The Northern bobwhite and mallard duck acute dietary studies were conducted at the same time in the same laboratory using 

the same feed. Therefore, the observance of body weight change at the same concentration level (262 mg a.i./kg diet) in both 

studies calls into question the validity of the effect as a result of the chemical versus some other factor.

Mammals - Technical

In an acute oral toxicity study (MRID 47267522), three per sex, fasted, young adult 
Page 60 of 114

C57BL mice [(age: 8- 13 weeks old, wt. males 23.0-25.7g, females 17.0-18.7g)] were 

given a single oral dose of the test material (BAS 560 F) prepared in 0.5% CMC solution 

in doubly distilled water in a sequential manner at a dose level of 2000 mg/kg bw by

gavage and observed for 14 days. The three females were dosed in step 1, and the three 

males in step 2. The oral LD50 is > 2000 mg/kg in mice which classifies the product 

(metrafenone technical) in EPA Toxicity Category III for oral toxicity.

One male animal died on Day 4. This animal showed poor general health, dyspnea, 

tremor, piloerection and sunken flanks. The dead mouse showed discoloration of the 

lungs, and ulcer/erosion in stomach. All other male and female animals survived showed 

no obnormalities, and gained body weight during the first week post-exposure. No gross 

abnormalities were noted for any of the surviving animals when necropsied at the 

termination.

Mammals – Formulation

In an acute oral toxicity study (MRID 47267609), 5/sex of Sprague-Dawley derived 

(Crl:CD(SD)BR) albino rats (age: 8 weeks; weight: 206-229 g males and 165-184 g 

females) were given a single oral dose of AC 375839 300 g/L SC (RLF12359) (Lot No. 

R2066-048; 294 g/L and 25.21% AC 375839; density 1.19 g/mL; pH 6.6; viscous beige 

liquid) as received at a dose of 5000 mg/kg bw administered by oral gavage. The amount 

of test solution to be administered was calculated for each animal. Animals were 

observed for clinical signs of toxicity and mortality several times on the day of dosing 

and daily for 14 days. Individual body weights were recorded prior to dosing (day 0) and 

on days 7 and 14. A gross necropsy examination was performed on all animals at 

scheduled euthanasia. All animals survived and gained weight. No clinical signs of 

toxicity were observed. No gross pathological findings were observed at necropsy. The 

oral LD50 is > 5000 mg/kg in rats which classifies the product (metrafenone formulation) 

in EPA Toxicity Category IV for oral toxicity.

Table 25. Mammalian Acute Toxicity Data 

Common 

Name

%AI Study parameters LD50 /NOAEL MRID Classification

/Category

Technical AC 375839 (a.k.a. BAS 560F)

Mouse 94.2 Acute oral study

2000 mg 

technical/kg bw 

(limit test) 

administered by 

gavage

3/sex/dose level

14-day observation 

period

Acute oral LD50 >2000 mg technical/kg bw 

(F, M, both)2

NOAEL: No NOAEL

LOAEL: No LOAEL

47267522 Acceptable/ 

Practically 

non-toxic1
Page 61 of 114

Table 25. Mammalian Acute Toxicity Data 

Common 

Name

%AI Study parameters LD50 /NOAEL MRID Classification

/Category

Formulation

Laboratory 

albino rat

25.21%; 

AC 

375839 

300 g/ L 

SC (RLF 

12359)

Acute oral study

5000 mg form/kg 

bw (limit test) 

administered by 

gavage

5/sex/dose level

14-day observation 

period

Acute oral LD50 >5000 mg form/kg bw (F, 

M, both) [> 1,260.5 mg a.i./kg bw] 3

NOAEL: No NOAEL

LOAEL: No LOAEL

47267609 Acceptable4/

Practically 

non-toxic1

1 Based on LD50 (mg/kg) <10 very highly toxic; 10-50 highly toxic; 51-500 moderately toxic; 501-2000 slightly toxic; >2000 

practically nontoxic

2 One male animal died on Day 4. This animal showed poor general health, dyspnea, tremor, piloerection and sunken flanks. 

The dead mouse showed discoloration of the lungs, and ulcer/erosion in stomach.

3 All animals survived and gained weight. No clinical signs of toxicity were observed. No gross pathological findings were 

observed at necropsy. 

4 The study satisfies the OECD Guideline 401, which is no longer considered an acceptable protocol. The preferred protocol is 

OECD 425: Acute Oral Toxicity-Up-and-Down Procedure. 

Terrestrial Invertebrates – Technical

The terrestrial invertebrate study on honey bees (Apis mellifera, MRID 47267508) 

classified as acceptable. The contact test had 4% mortality in the negative and solvent 

controls and 0% mortality in the 100 μg a.i./bee level by 48 hours; there were no sublethal effects in the contact test. The oral test also had 4% mortality in the negative 

control, 2% mortality in the solvent control, and 2% mortality in the 114 μg a.i./bee level

at 24 and 48 hours; sub-lethal effects were 0% in the negative control, 2% in the solvent 

control, and 6% in the 114 μg a.i./bee level only at 4 hours.

In a 14 day acute limit toxicity study, earthworms (Eisenia fetida, MRID 47267518) were 

exposed to AC 375839 at a nominal concentration of 1000 mg a.i./kg dry weight of 

artificial soil. No concurrent reference chemical test was conducted in this study. The 

report indicated that the experiment was carried out in accordance with OECD 207.

However, only one concentration was tested which did not fulfill the requirement of the 

guideline. No earthworm mortality was observed in the water control or test substance 

treatment. There was one mortality in the acetone control group. The 14 day LC50 was > 

1000 mg a.i./kg dry soil, the concentration tested. No significant difference in earthworm 

burrowing time (i.e., time needed for 10 earthworms to burrow into the soil after 

placement on soil surface) was observed. The average weight loss between Day 0 and 

Day 14 was 20.6, 3.5 and 39.7 mg in the test groups of water control, acetone control, 

and test substance treatment, respectively. There was a significant difference in weight 

change between acetone control and test substance treatment. However, there was no 

significant difference between the water control and the test substance. Therefore, the 

sub-lethal effect of AC 375839 at a concentration of 1000 mg a.i./kg dry wt soil on 
Page 62 of 114

weight loss is uncertain. The end-point toxicity concentration of AC 375839 can not be 

determined from this study, however, it is considered to be non-lethal to earthworms up 

to a concentration of 1000 mg a.i./kg dry soil. No other observable compound related 

toxicity effect was reported.

Terrestrial Invertebrates – Metabolites

In a 14 day acute toxicity study, earthworms (E. fetida, MRID 47267519) were exposed 

to CL 377160 at nominal concentrations of 0, 198, 296, 444, 667, and 1000 mg CL 

377160/kg dry weight of artificial soil. No concurrent reference chemical test was 

conducted in this study, however, the facility conducts annual test with 2-

chloroacetamide in a concentration range of 0 – 30 mg/kg dw of soil. The experiment was 

carried out in accordance with OECD 207. There were no observable compound related 

toxicity effects. No sub-lethal toxicity, specifically body weight loss, was observed. 

Calculations using the mean body weight for each treatment against the mean initial body 

weight (440 mg each) showed that there were body weight gains of 3.3%, 5.3%, 7.7%, 

10.5%, 4.6%, and 2.7% for the treatments of 0, 198, 296, 444, 667, 1000 mg/kg dry soil 

weight. No other toxicity effect was reported. In addition, no earthworm mortality was 

observed in the water control or in test substance treatments. The 14 day LC50 was > 

1000 mg/kg dw of soil. The 14 day NOEC, based on mortality and body weight, was 

1000 mg/kg dw of soil, the highest concentration tested. The CL 377160 is considered to 

be non-toxic to earthworms up to a concentration of 1000 mg/kg dw of soil based on this 

study. However, a freeze storage stability study submitted by the applicant (PMRA # 

1620213) showed that CL 377160 rapidly bound and degraded in soils even at – 5 oC. 

Therefore, the LC50 obtained from this study is uncertain and the actual LC50 could be 

lower. 

Terrestrial Invertebrates – Formulations

The terrestrial invertebrate study on honey bees (A. mellifera, MRID 47267606) 

classified as supplemental. The study uses a formulation to test toxicity. For honeybee 

acute contact toxicity studies, a TGAI test compound is required. Relative to a similar 

honeybee acute contact toxicity test (MRID 47267508), which shows no mortality at the 

treatment level (100 g a.i./bee), this formulation appears to be more toxic at a lower 

nominal concentration (100 g product./bee ≈ 24 g a.i./bee) having 24% mortality. This 

information suggests that there is something in the formulation that is more toxic than the 

active ingredient acting alone. Finally, the concentrations of test substance in the dosing 

solutions were not determined. Therefore, the actual dose levels used are unknown.

The contact test had 2% mortality in the negative and solvent controls and 24% mortality

in the 100 μg a.i./bee level by 48 hours; sub-lethal effects were 0% in the negative and 

solvent controls, and 10% in the 100 μg a.i./bee level only at 4 hours but not thereafter. 

The oral test also had 2% mortality in the negative control, 0% mortality in the solvent 

control, and 4% mortality in the 113.4 μg a.i./bee level by 48 hours; sub-lethal effects 

were 0% in the negative control, 2% in the solvent control, and 0% in the 113.4 μg 

a.i./bee level.
Page 63 of 114

In a 14 day acute limit toxicity study, earthworms (E. fetida, MRID 47267608) were 

exposed to AC 375839 300 g/L SC RLF12359 (SF10358) at 1000 mg formulation/kg dry

weight of artificial soil. No concurrent reference chemical test was conducted in this 

study. The report indicated that the experiment was carried out in accordance with OECD 

207. However, only one concentration was tested which did not fulfill the requirement of 

the guideline. No earthworm mortality was observed in the water control or in test 

substance treatment. The 14 day LC50 was > 1000 mg formulation/kg dry soil. No 

significant difference in earthworm burrowing time (i.e., time needed for 10 earthworms 

to burrow into the soil after placement on soil surface) was observed at day 7. The 

average weight loss between Day 0 and Day 14 was 20.6 and 87.9 mg in the test groups 

of water control and test substance treatment, respectively. The difference is statistically

significant. The 14 day NOEC, based on body weight loss, was < 1000 mg/kg dry soil, 

the concentration tested. The end-point toxicity concentration of the test substance can 

not be determined from this study; however, it is considered to be non-lethal to 

earthworms up to a concentration of 1000 mg formulation/kg dry soil. No other 

observable compound related toxicity effect was reported.

Table 26. Terrestrial Invertebrate Acute/Subacute Toxicity Data

Common 

Name

%AI Study parameters LD50 /NOAEL MRID Classification

/Category

Technical AC 375839 (a.k.a. BAS 560F)

Honey bees

Apis

Mellifera

95.86 48 hour acute 

contact and oral 

toxicity tests

5 reps. / 10 bees 

per rep.

Contact: 0 

(negative, solvent), 

100 μg a.i./bee; 

Oral: 0 (negative, 

solvent), 114 μg 

a.i./bee

48 hour contact LD50 > 100 g ai/bee

NOAEC: 100 μg a.i./bee

LOAEC > 100 μg a.i./bee 

48 hour oral LC50 > 114 g ai/bee

NOAEC: 114 μg a.i./bee

LOAEC > 114 μg a.i./bee 

47267508 Acceptable/ 

Practically 

non-toxic1

Earthworm 

Eisenia fetida

95.86 14 day acute limit 

toxicity

4 reps (treatment); 

1 rep (control) / 10 

earthworms per 

rep.

Nominal: 1,000 

mg a.i./kg dry soil

14 day LC50 >1,000 mg a.i./kg dry soil

NOAEC < 1,000 mg a.i./kg dry soil

LOAEC = 1,000 mg a.i./kg dry soil

Endpoint(s) affected: possibly weight loss

47267518 Supplemental/ 

Non-GLN2
Page 64 of 114

Table 26. Terrestrial Invertebrate Acute/Subacute Toxicity Data

Common 

Name

%AI Study parameters LD50 /NOAEL MRID Classification

/Category

Metabolites

Earthworm 

Eisenia fetida

97 CL 377160

(hydrolytic 

metabolite of 

metrafenone)

14 day acute 

toxicity

4 reps (treatment); 

1 rep (control) / 10 

earthworms per 

rep.

Nominal: 198, 296, 

444, 667, and 1000 

mg CL 377160/kg 

dry soil 

14-day LC50 >1,000 mg CL377160/kg dry 

soil

NOAEC: 1,000 mg CL 377160/kg dry soil

LOAEC: 1,000 mg CL 377160/kg dry soil

Endpoint(s) affected: none.

47267519 Supplemental/ 

Non-GLN2

Formulations 

Honey bees

Apis mellifera

24.4% 

a.i.; 

288 g/L

AC 375839 in a 

300 g/L SC 

(SF10358/ 

RLF12359)

48 hour acute 

contact and oral 

toxicity tests

5 reps. / 10 bees 

per rep.

Contact: 0 

(negative, solvent), 

100 μg test 

material3/bee; 

Oral: 0 (negative, 

solvent), 113.4 μg 

test material/bee

48 hour contact LD50 > 100 g form/bee

[>24.4 μg a.i./bee]

NOAEC < 100 μg form/bee [<24.4 μg 

a.i./bee]

LOAEC: 100 μg form/bee [24.4 μg a.i./bee]

48 hour oral LC50 > 113.4 g form/bee

[>27.7 μg a.i./bee]

NOAEC: 113.4 μg form/bee [27.7 μg 

a.i./bee]

LOAEC > 113.4 μg form/bee [> 27.7 μg 

a.i./bee]

47267606 Supplemental/ 

Practically 

non-toxic1
Page 65 of 114

Table 26. Terrestrial Invertebrate Acute/Subacute Toxicity Data

Common 

Name

%AI Study parameters LD50 /NOAEL MRID Classification

/Category

Earthworm 

Eisenia fetida

288 g 

a.i./L

AC 375839 300 

g/L SC RLF12359

(SF10358)

14 day acute limit 

toxicity

4 reps (treatment); 

1 rep (control) / 10 

earthworms per 

rep.

Nominal: 1,000 

mg form/kg dry 

soil

14 day LC50 >1,000 mg form4/kg dry soil

NOAEC < 1,000 mg form/kg dry soil

LOAEC < 1,000 mg form/kg dry soil

Endpoint(s) affected: body weight (i.e., 

weight loss)

47267608 Supplemental/ 

Non-GLN2

1 Based on acute contact LD50 (g a.i./bee) <2 highly toxic; 2-10.99 moderately toxic; ≥11 practically non-toxic

2 Deemed acceptable by PMRA

3

‘Test material’ is assumed to mean ‘formulation’

4 Not enough information provided in the study to determine active ingredient content

(2) Chronic Effects

Birds - Technical

The one-generation reproductive toxicity study (MRID 47267506) using 20 pairs per 

level of 12.5-month old Northern bobwhite quail (Colinus virginianus) over 22 weeks. 

BAS 560F was administered to the birds in the diet at nominal concentrations of 0 

(control), 185, 500, or 1350 mg ai/kg diet. Mean-measured concentrations were <3.75 

(<LOD, control), 181, 486, and 1320 mg ai/kg diet, respectively. No treatment-related 

effects were observed on any reproductive parameters at any concentration level. There 

was, however, a significant reduction (p=0.02, 43%) in adult male body weight gain at 

the 486 mg ai/kg diet level. While this response was not dose-dependent, similar effects 

(non-dose-dependent) on bird body weights were observed in the acute avian dietary 

studies with this test material. The lack of dose response in this case indicates that both 

the NOAEC and LOAEC will be ≥1320 mg a.i./kg diet. 

The one-generation reproductive toxicity study (MRID 47267507) used 16 pairs per level 

of ca. 5-month old mallard duck (Anas platyrhynchos) over 22 weeks. BAS 560 F was 

administered to the birds in the diet at nominal concentrations of 0 (control), 450, 900, or 

1350 mg ai/kg diet. Mean-measured concentrations were <18.6 (<LOQ, control), 438, 

848, and 1316 mg ai/kg diet, respectively. No treatment-related effects were observed on 

any adult parameter at any treatment level, or on any offspring parameter at the 438 and 

848 mg ai/kg diet levels. At the 1316 mg ai/kg diet level, a statistically-significant 

reduction in the number of eggs laid per hen per week was observed compared to the 

control (3.3 versus 4.5 eggs/hen/week). Hatchability was also reduced at the 1316 mg 
Page 66 of 114

ai/kg level, where the percentage of chicks “dead-in-shell” of fertile eggs increased from 

15.7% for the control level to 36.8% for the 1316 mg ai/kg diet level. As a direct result, 

the percentage of hatched chicks of fertile eggs was also statistically-different from the 

control (57.0 versus 77.0%). The study was deemed supplemental on account of several 

guideline deviations including lack of reporting for pre-test mortality, the initial age of 

the birds was below (ca. 5 months) recommended age (at least 7 months), and cage size 

was significantly smaller than recommended (OPPTS recommends at least 10,000 cm2

per bird; instead, the floor space was only 4225 cm2per bird).

Table 27. Avian Chronic Toxicity Data

Common Name %AI Study Parameters NOAEC/LOAEC MRID Classification

Technical AC 375839 (a.k.a. BAS 560F)

Northern 

Bobwhite Quail

Colinus 

virginianus

95.86 1-generation reproduction study

Pre-laying exposure 10 weeks; 

egg laying exposure 12 weeks

2 birds per pen (1 ♂: 1♀); 20 

pens per neg. control and 

treatment

Mean measured: <3.75 (neg. 

control), 181, 486, and 1320 mg 

a.i./kg diet

NOAEC ≥ 1320 mg 

a.i./kg diet

LOAEC ≥ 1320 mg 

a.i./kg diet

Endpoint(s) affected: 

none.

47267506 Acceptable

Mallard Duck

Anas 

platyrhynchos

99.4 1-generation reproduction study

Pre-laying exposure 10 weeks; 

egg laying exposure 12 weeks

2 birds per pen (1 ♂: 1♀); 20 

pens per neg. control and 

treatment

Mean measured: <18.6 (neg. 

control), 438, 848, and 1316 mg 

a.i./kg diet

NOAEC: = 848 mg

a.i./kg diet1

LOAEC: 1316 mg a.i./kg 

diet

Endpoint(s) affected: egg 

production (eggs laid per 

♀ per wk) and 

hatchability (% dead-inshell of fertile eggs)

47267507 Supplemental

1 Bold value is the value that will be used to calculate risk quotients

Mammals - Technical

In a rat 2-generation reproduction study (MRIDs 46415729, 46415728) and given the 

parental animals, no treatment-related effects were observed on mortality, clinical signs 

of toxicity, or macroscopic examinations. The LOAEL for parental toxicity is 1000 ppm 

(equivalent to 72.8/84.8 mg/kg bw/day [M/F]), based on decreased body weights and 

body weight gains in the F1 males. The NOAEL is 500 ppm (equivalent to 35.9/42.9 

mg/kg bw/day [M/F]). In the offspring, no effects of treatment were observed on clinical 

signs of toxicity, litter parameters, sexual maturation, anogenital distance, hematology, or 

macroscopic or microscopic pathology. The LOAEL for offspring toxicity is 10,000 ppm 

(equivalent to 759/864 mg/kg bw/day [M/F]), based on decreased body weights in the F1

and F2 pups. The NOAEL is 1000 ppm (equivalent to 72.8/84.8 mg/kg bw/day [M/F]). 
Page 67 of 114

No effects of treatment were observed on estrous cycle number or length, sperm 

parameters, primordial follicle count, or reproductive performance. Thus, the LOAEL for 

reproductive performance was not observed. The NOAEL for reproductive performance 

is 10,000 ppm (equivalent to 759/864 mg/kg bw/day [M/F]).

In a rat developmental toxicity study (MRID 46415726), no treatment-related effects 

were observed on mortalities, clinical signs, body weights, body weight gains, food 

consumption, hematology, liver weights, liver histology, or gross pathology relative to 

maternal toxicity. Therefore, the maternal LOAEL was not observed. The maternal 

NOAEL is 1000 mg/kg/day (limit dose). Regarding developmental toxicity: there were 

no treatment-related effects on the numbers of litters, fetuses (live or dead), resorptions 

(early, late, or complete litter) or on sex ratio or post-implantation loss, on fetal body 

weights or on skeletal ossification, indicating no effect on fetal growth or development; 

there were no treatment-related external, visceral, or skeletal variations on development 

or other malformations. Thus, the developmental LOAEL was not observed. The 

developmental NOAEL is 1000 mg/kg/day (limit dose).

In a rabbit developmental toxicity study (MRID 46415727), no treatment-related effect 

was observed on mortalities, hematology, or gross pathology relative to maternal toxicity. 

Therefore, the maternal LOAEL is 350 mg/kg/day, based on decreased body weight gains 

and food consumption; increased liver weights; and increased incidences and/or severity 

of periportal hepatocellular hypertrophy and diffuse hepatocellular vacuolation. The 

maternal NOAEL is 50 mg/kg/day. Regarding developmental toxicity: there were no 

treatment-related effects on the numbers of litters, fetuses (live or dead), resorptions 

(early, late, or complete litter) or on sex ratio or post-implantation loss, on fetal body 

weights or on skeletal ossification, indicating no effect on fetal growth or development; 

there were no treatment-related external, visceral, or skeletal variations on development 

or other malformations. Thus, the developmental LOAEL was not observed. The 

developmental NOAEL is 700 mg/kg/day.
Page 68 of 114

Table 28. Mammalian Chronic Toxicity Data

Common Name %AI Study Parameters NOAEC/

LOAEC

MRID Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Rat 95.86 2-generation reproduction study 

30 CD Sprague-Dawley

rats/sex/group/generation, by 

feeding (diet).

3 treatment groups; 1 untreated 

diet control group

Nominal: 0, 5001, 1000, 10000 

ppm

M: 0, 35.9, 72.8, 759 mg BAS 

560 F/kg/day

F: 0, 42.9, 84.8, 864 mg BAS 

560 F/kg/day

Parental systemic 

NOAEL (M/F): 

35.9/42.9 mg/kg 

bw/day1

LOAEL (M/F): 

72.8/84.8 mg/kg 

bw/day, based on 

decreased body wts 

and body wt gain F1

males as well as body 

wts in F1 and F2

females

Offspring/Developmental Toxicity 

NOAEL (M/F): 

72.8/84.8 mg/kg 

bw/day

LOAEL (M/F): 

759/864 mg/kg 

bw/day, based on 

decreased body wts in 

F1 and F2 pups 

Reproductive Toxicity 

NOAEL (M/F): 

759/864 mg/kg 

bw/day

LOAEL (M/F): not 

attained

46415729

46415728

Acceptable / 

Guideline

Rat 95.86 Developmental toxicity study

25 rats per dose, by gavage.

3 treatment groups; 1 untreated 

control group

0, 50, 500, 1000 mg BAS 560 

F/kg/day

Maternal

NOAEL: 1000 

mg/kg/day (HDT; 

limit dose)

LOAEL: not attained

Developmental

NOAEL: 1000 

mg/kg/day (HDT; 

limit dose)

LOAEL: not attained

46415726 Acceptable/ 

Guideline
Page 69 of 114

Table 28. Mammalian Chronic Toxicity Data

Common Name %AI Study Parameters NOAEC/

LOAEC

MRID Classification/

Category

Rabbit 95.86 Developmental toxicity study

25 rabbits per group, by gavage.

3 treatment groups; 1 untreated 

control group

0, 50, 350, 700 mg BAS 560 

F/kg/day

Maternal

NOAEL: 50 

mg/kg/day

LOAEL: 350 

mg/kg/day, based on 

decreased body wt 

gains and food 

consumption; 

increased liver wts; 

increased incidences 

and/or severity of 

periportal 

hepatocellular 

hypertrophy and 

diffuse hepatocellular 

vacuolation

Developmental

NOAEL: 700 

mg/kg/day (HDT)

LOAEL: not attained

46415727 Acceptable/ 

Guideline

1 Bold value is the value that will be used to calculate risk quotients
Page 70 of 114

b. Terrestrial Plants

The two tier I terrestrial plant studies, seedling emergence (MRID 47267509) and 

vegetative vigor (MRID 47267510), are both supplemental and are based on the 

UK/EU formulation (BAS 560 00F, 42.8% purity). The lower application rates in the 

studies (0.091 and 0.288 lbs a.i./A for the seedling emergence study; and, 0.091 and 

0.285 lbs a.i./A for all but soybean [0.099 and 0.283 lbs a.i./A] for the vegetative vigor 

study) relative to the label application rate (0.3 lbs a.i./A) leads to uncertainty in the 

risk characterization especially as effects were noted, but the NOAEC and EC05 are 

undefined. The latter two endpoints are used for endangered species risk calculations, 

which cannot be done in this case. Tier II tests are requested to define the latter 

endpoints, to have a study available that is based on the U.S. formulation, and, 

subsequently, reduce uncertainty in risk characterization.

All species were not significantly affected by the two treatments in the seedling 

emergence study. The most sensitive monocot and dicot species could not be 

determined. The NOAEC for all species (monocot and dicot5) was 0.288 lbs ai/A. The 

EC05, EC25 >0.288 lbs a.i./A. For the highest treatment level tested, the following 

effects were noted -- the % inhibition relative to control that is greater than 5% was 

observed in the following plants for the given endpoint: emergence (oat, tomato); 

survival (oat, onion, tomato), dry weight (onion, ryegrass), and height (cucumber, 

onion, soybean, tomato). 

All species were not significantly affected by the two treatments in the vegetative vigor 

study. The most sensitive monocot and dicot species could not be determined. The 

NOAEC for all monocot species was 0.285 lbs ai/A. The EC05, EC25 >0.285 lbs a.i./A. 

The NOAEC for all dicot species was the same as that for the monocots except for the 

soybean6 which was 0.283 lbs a.i./A (with the EC05 and EC25 > 0.283 lbs a.i./A). For 

the highest treatment level tested, the following effects were noted -- the % inhibition 

relative to control that is greater than 5% was observed in the following plants for the 

given endpoint: dry weight (ryegrass) and height (none). 

 

5 Monocots include corn, Zea mays; oat, Avena sativa; onion, Allium cepa; and ryegrass, Lolium Perenne). 

Dicots include cucumber, Cucumis sativa; lettuce, Lactuca sativa; oilseed rape, Brassica napus; soybean, 

Glycine max; sugarbeet, Beta vulgaris; and tomato, Lycopersicon esculentum.

6

Soybean was treated with the test substance on a different day than the other species, and the 

concentration of metrafenone in the test substance was analyzed on the same day, thus soybean had a 

different measured concentration than the other test species.
Page 71 of 114

IV. Risk Characterization

A. Risk Estimation –Integration of Exposure and Effects Data

A quantitative estimation of risk integrates EECs and toxicity estimates and 

evaluates the likelihood of adverse ecological effects to non-target species. In a 

deterministic approach, an exposure estimate is divided by a single point estimate of 

toxicity to calculate a risk quotient (RQ). The RQ is then compared to Agency Levels of 

Concern (LOCs, Appendix H), which serve as criteria for categorizing potential risk to 

non-target organisms and the need to consider regulatory action. 

1. Risk to Aquatic Animals and Plants

The greatest amount of uncertainty in the assessment stems from aquatic studies which 

were largely based on total concentrations (both dissolved and undissolved) of the test 

compound. In all cases (except for the chronic study on the saltwater mysid, but including 

aquatic plants), the risk quotient values were not calculated.

a. Aquatic Animals

1. Risk following acute exposure

Freshwater Fish and Aquatic-Phase Amphibians

The acute aquatic risk quotients (RQs) for freshwater fish and aquatic-phase amphibians 

were not calculated. Test compound in solution was not centrifuged and measured (postcentrifugation) in any of the acute freshwater fish studies (on the technical, metabolites, 

and formulations), even though higher concentrations tested exceeded or likely exceeded 

the solubility limit of the test compound. Without centrifugation, the amount of chemical 

that is freely dissolved and bioavailable cannot be determined. Uncertainty in the level of

dissolved test compound in the solution for all studies renders calculated endpoints 

suitable for qualitative use only.

Freshwater Invertebrates

The acute aquatic risk quotients (RQs) for freshwater invertebrates were not calculated. 

Test compound in solution was not centrifuged and measured (post-centrifugation) in any 

of the acute freshwater invertebrate studies (on the technical, metabolites, and 

formulations), even though higher concentrations tested exceeded or likely exceeded the 

solubility limit of the test compound. Without centrifugation, the amount of chemical that 

is freely dissolved and bioavailable cannot be determined. Uncertainty in the level of 
Page 72 of 114

dissolved test compound in the solution for all studies renders calculated endpoints 

suitable for qualitative use only.

Marine/Estuarine Fish

The study on the technical active ingredient (MRID 47267446) yielded an LC50 greater 

than the highest concentration tested because there were no mortalities and no sublethal 

effects; therefore, RQs are not reported.

Marine/Estuarine Invertebrates

The acute aquatic risk quotients (RQs) for marine/estuarine invertebrates were not 

calculated. Test compound in solution was not consistently centrifuged and measured 

(post-centrifugation) in any of the acute marine/estuarine invertebrate studies (on the 

technical), even though higher concentrations tested exceeded or likely exceeded the 

solubility limit of the test compound. Without centrifugation, the amount of chemical 

that is freely dissolved and bioavailable cannot be determined. Uncertainty in the level of 

dissolved test compound in the solution for all studies renders calculated endpoints 

suitable for qualitative use only.

2. Risk following chronic exposure

Freshwater Fish and Aquatic-Phase Amphibians

The chronic aquatic risk quotients (RQs) for freshwater fish and aquatic-phase 

amphibians were not calculated. Test compound in solution was not centrifuged and 

measured (post-centrifugation) in the chronic freshwater fish study (on the technical), 

even though higher concentrations tested exceeded or likely exceeded the solubility limit 

of the test compound. Without centrifugation, the amount of chemical that is freely 

dissolved and bioavailable cannot be determined. Uncertainty in the level of dissolved 

test compound in the solution for this study renders calculated endpoints suitable for 

qualitative use only.

Freshwater Invertebrates

No acceptable guideline and non-guideline chronic studies on freshwater invertebrates 

are available. Therefore, a quantitative estimation of risk cannot be conducted. Chronic 

risk to freshwater invertebrates cannot be precluded.

Marine/Estuarine Fish

No chronic studies on marine/estuarine fish are available. Therefore, a quantitative 

estimation of risk cannot be conducted. Chronic risk to marine/estuarine fish cannot be 

precluded.

Marine/Estuarine Invertebrates
Page 73 of 114

The chronic aquatic LOC was not exceeded for the proposed use of metrafenone for the 

technical tested. Table 29 summarizes the RQ values and scenarios used to compare to 

chronic aquatic LOCs for marine invertebrates.

Table 29. Metrafenone: Chronic Risks to Marine/Estuarine Invertebrates (Application Rate 0.3 

lbs a.i./A, 6 Applications/Year)

Species Toxicity Endpoint 

(μg/L)

Scenario 21-Day 

EEC

(μg/L)

Chronic 

Risk 

Quotient1

Levels of 

Concern 

Exceeded2

Saltwater mysid

Americamysis 

bahia

NOAEC= 22

g a.i./L

Technical

Grapes (Metrafenone)

NY Grapes

CA Grapes

8.82

1.10

0.40

0.05

No

No

Saltwater mysid

Americamysis 

bahia

NOAEC= 22

g a.i./L

Technical

Grapes (Total Metrafenone 

Residues)

NY Grapes

CA Grapes

17.67

1.89

0.80

0.09

No

No

1 Chronic Risk Quotients are calculated using the following formula: EEC/NOAEC

2 Chronic LOC for marine/estuarine invertebrates = 1

b. Aquatic Plants

The aquatic plant risk quotients (RQs) were not calculated. Test compound in solution 

was not centrifuged and measured (post-centrifugation) in these studies (on the technical, 

metabolites, and formulations), even though higher concentrations tested exceeded or 

likely exceeded the solubility limit of the test compound. Without centrifugation, the 

amount of chemical that is freely dissolved and bioavailable cannot be determined. 

Uncertainty in the level of dissolved test compound in the solution for these studies 

renders calculated endpoints suitable for qualitative use only.

2. Risk to Terrestrial Animals and Plants

a. Terrestrial Animals

To assess risks of metrafenone to non-target birds and mammals, EECs and acute and 

chronic RQs for residues on various forage categories (short grass, tall grass, broadleaf 

plants/small insects, fruits/pods/large insects, and seeds) were obtained from the Tier 1 

model, T-REX v. 1.4.1 for foliar spray applications to the proposed crops. The model 

assumes initial concentrations on plant surfaces based on Kenaga predicted maximum 

residues as modified by Fletcher et al. (1994), and assumes first-order dissipation. In this 

case, six applications at 0.3 lbs a.i./A were used. 
Page 74 of 114

For birds, acute RQs are derived using dose-based and dietary-based acute toxicity

values. For mammals, acute RQs are derived using a dose-based acute toxicity value, 

and chronic RQs are derived using a dose-based chronic toxicity value (the test material 

was administered by gavage) and a dietary-based chronic toxicity value using the 

standard FDA laboratory rat conversion value provided in the T-REX model. Dietarybased RQs are calculated using EECs expressed in terms of residue concentration for the 

various forage categories and toxicity values (LC50 or NOAEC) expressed in units of 

dietary concentration. Dose-based RQs are calculated using a body weight-adjusted LD50

and consumption-weighted equivalent dose sorted by food source and body size. For 

both birds and mammals, three weight categories (or sizes) are considered.

1. Risk following acute exposure

Birds

The acute oral and dietary endpoints are both greater than the highest concentrations 

tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg diet, respectively). There were no 

mortalities or treatment related clinical signs of toxicity in the acute oral studies; one 

death in each dietary study was observed but was not considered treatment related. 

Therefore, RQ values are not reported. Further discussion will be provided in the risk 

description. 

Potential risk to piscivorous birds

The potential risk to piscivorous birds considers exposure via consumption of fish

contaminated with metrafenone total residues. However, the acute oral and dietary

endpoints are both greater than the highest concentrations tested (>2025 mg a.i./kg bw 

and >6070 mg a.i./kg diet, respectively). There were no mortalities or treatment related 

clinical signs of toxicity in the acute oral studies; one death in each dietary study was 

observed but was not considered treatment related. Therefore, RQ values are not 

reported. Further discussion will be provided in the risk description. 

Mammals 

The acute endpoints for mammals are both greater than the highest concentrations tested 

(LD50: >2000 mg technical/kg bw, mouse; >5000 mg form/kg bw, rat). There were no 

mortalities or treatment related clinical signs of toxicity in the acute oral rat study; one 

death was observed in the acute oral mouse study. Therefore, RQ values are not reported. 

Further discussion will be provided in the risk description. 

Potential risk to piscivorous mammals

The potential risk to piscivorous mammals considers exposure via consumption of fish 

contaminated with metrafenone total residues. However, the mammalian acute endpoints 
Page 75 of 114

are both greater than the highest concentrations tested (LD50: >2000 mg technical/kg bw, 

mouse; >5000 mg form/kg bw, rat). A male mouse died in the acute oral mouse study

(MRID 47267522) on the technical; there were no mortalities in the acute oral rat study

(MRID 47267609) on the formulation. Therefore, RQ values are not reported. Further 

discussion will be provided in the risk description.

Terrestrial invertebrates

Metrafenone is classified as ‘practically non-toxic’ to honey bees on an acute contact 

basis, based on available data for the TGAI and formulation (24.4% a.i.). Given a nonguideline acute earthworm study using the technical active ingredient, metrafenone is 

considered to be non-lethal to earthworms up to a concentration of 1000 mg a.i./kg dry

soil. Similarly, given a non-guideline acute earthworm study using a metrafenone 

metabolite, the metabolite too is considered to be non-lethal to earthworms up to a 

concentration of 1000 mg/kg dry weight of soil. In addition, given a non-guideline acute 

earthworm study using a formulation, the formulation is also considered to be non-lethal 

to earthworms up to a concentration of 1000 mg formulation/kg dry soil. Additional 

discussion is provided in the risk description section.

2. Risk following chronic exposure

Birds

Utilizing the chronic endpoint (848 mg a.i./kg diet) from a 1-generation reproduction 

study (MRID 47267507) conducted with mallard duck and the T-REX model v.1.4.1, the

chronic avian dietary-based RQs do not exceeded the chronic LOC for birds for any food 

category.

Table 30. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

Grapes: 0.3 lbs a.i./A; 6 Applications/season

NOAEC 

(ppm)

EECs and RQs1,2,3

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

181 241.01 0.28 110.46 0.13 135.57 0.16 15.06 0.02

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on avian chronic NOAEC = 848 mg a.i./kg diet
Page 76 of 114

Potential risk to piscivorous birds

The potential risk to piscivorous birds considers exposure via consumption of fish 

contaminated with metrafenone total residues. None of the RQs exceed the chronic LOC 

for birds. The following table provides estimated RQs from KABAM using the 

maximum application rate and the scenario yielding the highest aquatic EECs (New York 

Grapes scenario; metrafenone total residue and high runoff scenario). 

Table 31. Chronic RQ values for Birds Consuming Fish Contaminated by 

Metrafenone (based on KABAM)1

Wildlife Species Dose Based Dietary Based2,3

sandpipers N/A 0.016

cranes N/A 0.016

rails N/A 0.018

herons N/A 0.019

small osprey N/A 0.022

white pelican N/A 0.023

N/A = Not applicable

1 NY Grapes scenario (at 0.3 lbs a.i./A with 6 applications/year) 

2 Based on avian chronic NOAEC = 848 mg a.i./kg diet

3 LOC for chronic risk = 1.0

Mammals

The chronic LOC is exceeded on a dose basis for mammals in all size classes eating short 

grass, for the 15 and 35 gram size classes eating tall grass and broadleaf plants / small 

insects. The chronic LOC on a dietary basis is not exceeded for any of the food 

categories. Risks to mammals following chronic exposure will be further discussed in the 

risk description section.

Table 32. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients 

Grapes: 0.3 lbs a.i./A; 6 Applications/season

NOAEC 

(ppm)

EECs and RQs1,2, 3

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

500 241.01 0.48 110.46 0.22 135.57 0.27 15.06 0.03

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on mammalian chronic dietary NOAEL: 500 mg/kg diet
Page 77 of 114

Table 33. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients

Size Class

(grams)

Adjusted 

NOAEL

EECs and RQs1,2, 3

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large 

Insects

Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 78.90 229.78 2.914105.32 1.33 129.25 1.64 14.36 0.18 3.19 0.04

35 63.84 158.81 2.49 72.79 1.14 89.33 1.40 9.93 0.16 2.21 0.03

1000 27.61 36.82 1.33 16.88 0.61 20.71 0.75 2.30 0.08 0.51 0.02

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on mammalian chronic dose-based NOAEL: 35.9 mg/kg bw/day

4 Bolded values exceed LOC

Potential risk to piscivorous mammals

The potential risk to piscivorous mammals considers exposure via consumption of fish 

contaminated with metrafenone total residues. None of the RQs exceed the chronic LOC 

for mammals. The following table provides estimated RQs from KABAM using the 

maximum application rate and the scenario yielding the highest aquatic EECs (New York 

Grapes scenario; metrafenone total residue and high runoff scenario). 

Table 34. Chronic RQ Values for Mammals Consuming Fish Contaminated by 

Metrafenone (based on KABAM) 1

Wildlife Species Dose Based2,3 Dietary Based2,3

fog/water shrew 0.103 0.019

rice rat/star-nosed 

mole 0.125 0.018

small mink 0.159 0.025

large mink 0.176 0.025

small river otter 0.189 0.025

large river otter 0.219 0.027

1 NY Grapes scenario (at 0.3 lbs a.i./A with 6 applications/year) 

2 Based on mammalian chronic NOAEC = 35.9 mg/kg bw/day

3 LOC for chronic risk = 1.0
Page 78 of 114

b. Terrestrial Plants

Terrestrial plant risk quotients were not calculated on account of indeterminate endpoints 

generated in both the seedling emergence and vegetative vigor studies.

B. Risk Description

Based on the available ecotoxicity data and predicted environmental exposures, this 

ecological risk assessment supports the presumption of risk to mammals following 

chronic exposure. 

1. Risk to Aquatic Animals and Plants

a. Aquatic Animals

1. Risk following acute exposure

Freshwater Fish and Aquatic-Phase Amphibians

Technical

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

acute rainbow trout study (MRID 47267443) indicated only 5% mortality at levels below 

(0.065 mg total a.i./L) and above (0.43 and 0.82 mg total a.i./L) the solubility limit, 

which implies the effect may not be dose related; 16% of fish were lethargic and 5% 

exhibited dark discoloration after 96 hours only at the highest concentration tested (0.82 

mg total a.i./L). The acute bluegill sunfish study (MRID 47267442) indicated 15% 

mortality, 18% lethargic fish, and 12% virtually immobile but respiring fish at the highest 

concentration tested (0.87 mg total a.i./L) after 96 hours. Given that the test solution was 

not centrifuged, the amount of actual dissolved active ingredient potentially leading to the 

observed effects is unknown. Nevertheless, given these studies and assuming that 

metrafenone concentrations in the environment reach the solubility limit, the effect of the 

technical grade active ingredient on freshwater fish is likely to be low. However, 

according to the model estimated EECs (0.00153 - 0.02 mg/L, which includes 

metrafenone and total metrafenone residue scenarios), levels of metrafenone at the 

solubility limit are not expected to occur in the environment given the proposed grape 

use. Therefore, acute risk to freshwater fish and aquatic-phase amphibians is not expected 

as a result of metrafenone use on grapes given the results from the studies using technical 

grade active ingredient.

Metabolites/Degradates

The limits of water solubility for metabolites of metrafenone were not reported in the 

available studies; exceedance of solubility limit for a given metabolite (Reg. No. 

4084564) was assumed given observed undissolved test substance in all five treatment 

groups of one acute study (MRID 47267445). The acute rainbow trout study (MRID 

47267444) was a limit test with no effects noted at 99 mg total a.i./L. Another acute 
Page 79 of 114

rainbow trout study (MRID 47267445) indicated 80% mortality at 20.3 mg total a.i./L 

and 100% mortality at 35.2 and 58.4 mg total a.i./L; sublethal effects were observed in 

the three highest concentrations: 20.3 mg total a.i./L (tottering, apathy, and distended 

abdomen), 35.2 mg total a.i./L (apathy and distended abdomen), and 58.4 mg total a.i./L 

(tottering and distended abdomen). Given that the test solution was not centrifuged, the 

amount of actual dissolved metabolite potentially leading to the observed effects is 

unknown. According to the model estimated EECs (0.00225 - 0.02 mg/L, which includes 

total metrafenone residue scenarios), levels of metrafenone metabolites at the tested 

levels are not expected to occur in the environment given the proposed grape use. 

Therefore, the effect of metrafenone metabolites on freshwater fish is likely to be low.

Formulations

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

acute study (MRID 47267605) using a formulation (BAS 560 00F, SF 10358, RLF 

12359) indicated no effects on rainbow trout at concentrations above the solubility limit, 

from 3.0 to 23.3 mg total a.i./L. Given that the test solution was not centrifuged, the 

amount of actual dissolved active ingredient is unknown. Not unlike the conclusion 

drawn for the technical active ingredient, given this study and assuming that metrafenone 

concentrations in the environment reach the solubility limit, the effect of this particular 

formulation on freshwater fish is likely to be low. However, according to the model 

estimated EECs (0.00153 - 0.02 mg/L, which includes metrafenone and total metrafenone 

residue scenarios), levels of metrafenone at the solubility limit are not expected to occur 

in the environment given the proposed grape use. Although this EU/UK formulation 

closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not its equivalent. 

Therefore, the effect of the U.S. formulated product on freshwater fish and aquatic-phase 

amphibians is not known.

Freshwater Invertebrates

Technical

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

acute study (MRID 47267437), in which the three highest concentrations (0.22, 0.45, and 

0.92 mg total a.i./L) were at or above the solubility limit, indicated no effects on daphnia. 

Given that the test solution was not centrifuged, the amount of actual dissolved active 

ingredient is unknown. Nevertheless, given this study and assuming that metrafenone 

concentrations in the environment reach the solubility limit, the effect of the technical 

grade active ingredient on freshwater invertebrates is likely to be low. However, 

according to the model estimated EECs (0.00153 - 0.02 mg/L, which includes 

metrafenone and total metrafenone residue scenarios), levels of metrafenone at the 

solubility limit are not expected to occur in the environment given the proposed grape 

use. Therefore, acute risk to freshwater invertebrates is not expected as a result of 

metrafenone use on grapes given the results from the studies using technical grade active 

ingredient.
Page 80 of 114

Metabolites/Degradates

The limits of water solubility for metabolites of metrafenone were not reported in the 

available studies. The acute daphnia study (MRID 47267438) with CL 375816 indicated

no effects. Another acute daphnia study (MRID 47267439) indicated 5, 55, and 65% 

immobility at the three highest concentrations 23.2, 49.6, and 66.4 mg total a.i./L, 

respectively, after 48 hours (test termination). Given that the test solution was not 

centrifuged, the amount of actual dissolved metabolite potentially leading to the observed 

effects is unknown. According to the model estimated EECs (0.00225 - 0.02 mg/L, which 

includes total metrafenone residue scenarios), levels of metrafenone metabolites at the 

tested levels are not expected to occur in the environment given the proposed grape use. 

Therefore, the effect of metrafenone metabolites on freshwater invertebrates is likely to 

be low.

Formulations

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

acute study (MRID 47267604) using a formulation (BAS 560 00F, SF 10358, RLF 

12359) indicated 65 and 90% mortality at the two highest concentrations 6.0 and 11.6 mg 

total a.i./L, respectively, at 48 hours (test termination); 5% immobility was observed in 

the negative control, 0.76 and 1.5 mg total a.i./L concentrations, 15% at 3.0 mg total 

a.i./L, and 25% at 6.0 mg total a.i./L. Given that the test solution was not centrifuged, the 

amount of actual dissolved active ingredient potentially leading to the observed effects is 

unknown. Not unlike the conclusion drawn for the technical active ingredient, given this 

study and assuming that metrafenone concentrations in the environment reach the 

solubility limit, the effect of this particular formulation on freshwater invertebrates is 

potentially low. However, according to the model estimated EECs (0.00153 - 0.02 mg/L, 

which includes metrafenone and total metrafenone residue scenarios), levels of 

metrafenone at the solubility limit are not expected to occur in the environment given the 

proposed grape use. Although this EU/UK formulation closely matches the U.S. 

formulation (i.e., BAS 560 03F) it is still not its equivalent. Therefore, the effect of the 

U.S. formulated product on freshwater invertebrates is not known.

Marine/Estuarine Fish

The study on the technical active ingredient (MRID 47267446) yielded an LC50 greater 

than the highest concentration tested because there were no mortalities and no sublethal 

effects; therefore, RQs were not reported. Comparison of the peak aquatic EECs (0.02 

mg/L, taken from the total metrafenone residue scenario) with the highest concentration 

tested (0.65 mg a.i./L uncentrifuged; 0.35 mg a.i./L centrifuged) shows that the EECs 

were at least 17 times less than the highest concentrations tested in the studies. Therefore, 

acute risk to marine/estuarine fish is not expected as a result of metrafenone use on 

grapes.

Marine/Estuarine Invertebrates
Page 81 of 114

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

acute eastern oyster study (MRID 47267440) indicated effects on shell deposition, 

whereby relative to the negative control the mean percent reduction in shell growth 

starting with the negative solvent (then, 0.0522, 0.104, 0.203, 0.287 mg total a.i./L, and 

0.33 mg dissolved a.i./L) is as follows: 17.4, 13.9, 26.3, 44.3, 84.2, and 100%, 

respectively. Therefore, should concentrations in the environment reach the solubility

limit, the acute risk to marine/estuarine invertebrates may be expected. However, given 

that the test solution was not centrifuged for all but the highest test concentration, the 

amount of actual dissolved active ingredient potentially leading to the observed effects is 

unknown. Meaning that interpretation of effects from total concentrations cited here may

underestimate potential risk. Similarly, the acute saltwater mysid study (MRID 

47267441) indicated a dose related effect, this time on mortality at the four out of five 

highest concentrations: 5% at 0.129 and 0.240 mg total a.i./L, 15% at 0.416 mg total 

a.i./L, and 95% at 0.663 mg total a.i./L; in addition, erratic swimming was observed in 

the two highest concentrations by test termination. Despite the dose response, without 

centrifugation, the amount of chemical that is freely dissolved and bioavailable cannot be 

determined and, again, interpretation of effects from total concentrations cited here may

underestimate potential risk. However, according to the model estimated EECs (0.00153 -

0.02 mg/L, which includes metrafenone and total metrafenone residue scenarios), levels 

of metrafenone at the solubility limit are not expected to occur in the environment given 

the proposed grape use. Given these studies and assuming that metrafenone 

concentrations in the environment are not likely to reach the solubility limit, the acute

risk to marine/estuarine invertebrates is not expected.

2. Risk following chronic exposure

Freshwater Fish and Aquatic-Phase Amphibians

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L at 12oC. The 

chronic fathead minnow study (MRID 47267449) indicated post-hatch survival (28-days 

post-hatch) was statistically-reduced compared to the negative control at the three highest 

concentrations 0.227, 0.421, and 0.839 mg total a.i./L (p≤0.05). Post-hatch survival 

averaged 96% at the negative control through 0.118 mg total a.i./L levels, and 87, 86, and 

11% at the 0.227, 0.421, and 0.839 mg total ai/L levels, respectively. Therefore, a dose 

response is evident and implies that should concentrations in the environment reach the 

solubility limit, the chronic risk to freshwater fish may be expected. No clinical signs of 

toxicity were observed during the study in any treatment group. Fish length was 

significantly reduced relative to the average negative control length at the two highest 

concentrations 0.421 and 0.839 mg total ai/L and wet and dry weight were significantly 

lower than the negative control weights at the highest concentration (0.839 mg total a.i./L

level); however, significant impact on survival occurred at these levels. Given that the 

test solution was not centrifuged, the amount of actual dissolved active ingredient 

potentially leading to the observed effects is unknown. For example, the NOAEC value is 

low (0.118 mg total a.i./L) even though the measured concentration includes dissolved 
Page 82 of 114

and undissolved substance, but had the sample been centrifuged – including the dissolved 

compound only - the value would likely be lower. Therefore, conclusions drawn from 

these data would lead to an underestimation of potential risk. According to the model 

estimated EECs (0.00075 - 0.017 mg/L, which includes metrafenone and total 

metrafenone residue scenarios), levels of metrafenone at the solubility limit are not 

expected to occur in the environment given the proposed grape use. Assuming that 

metrafenone concentrations in the environment are not likely to reach the solubility limit 

or the concentrations used in this study7, the chronic risk to freshwater fish and aquaticphase amphibians is not expected.

Freshwater Invertebrates

No acceptable chronic ecotoxicity studies on freshwater invertebrates are available. 

Chronic risk to freshwater invertebrates cannot be precluded. 

Marine/Estuarine Fish

No chronic ecotoxicity studies on estuarine/marine fish have been submitted to the 

Agency for review. Chronic risk to estuarine/marine fish cannot be precluded.

Marine/Estuarine Invertebrates

The chronic aquatic LOC was not exceeded for the proposed use of metrafenone for the 

technical active ingredient (MRID 47267448) tested on the marine/estuarine invertebrate 

(saltwater mysid); no data is available for metabolites or formulation studies on 

marine/estuarine invertebrates. Although reproduction (number of offspring per female 

per reproductive day) was the (most sensitive) affected endpoint in this study, yielding a 

definitive endpoint, the RQ calculations indicate that chronic risk to marine/estuarine 

invertebrates is not expected as a result of metrafenone use.

b. Aquatic Plants

For all aquatic plant studies, dissolved or soluble concentrations (i.e., post-centrifugation) 

of test material were not determined. Without centrifugation, the amount of chemical that 

is freely dissolved and bioavailable cannot be determined. This is especially a problem as 

some of the testing concentrations were conducted above the solubility limit of the 

technical grade active ingredient (MRID 47267511, 47267512, 47267513, 47267514, 

47267515, technical; MRID 47267607, formulation). In addition, the metabolite 

solubility limit is unknown which leads to uncertainty in interpreting the measured 

concentrations in the metabolite studies (MRID 47267516, 47267517). The lowest

 

7 The acute eastern oyster study (MRID 47267440) using the technical grade active ingredient indicated a 

42% reduction in concentration from uncentrifuged sample to centrifuged sample. If the percentage is 

applied to the NOAEC value from this study, 0.118 mg total a.i./L, it would reduce to 0.068 mg a.i./L, 

which is still above the highest model estimated EEC value (0.02 mg/L).
Page 83 of 114

concentration tested among the vascular plants (MRID 47267511, L. gibba: 0.057 mg 

total a.i./L; or, 0.033 mg a.i./L assuming a 42% reduction after hypothetical 

centrifugation8) and non-vascular plants (MRID 47267513, S. costatum: 0.0509 mg total 

a.i./L; or 0.0295 mg a.i./L9) is higher than the highest peak aquatic EEC value of 0.02

mg/L (assuming the total metrafenone residue scenario). Therefore, had valid endpoints

(i.e., those based on dissolved concentrations) been determined using these studies, they

would likely be greater than the highest model predicted concentration in the 

environment, which implies that risk to vascular and non-vascular species is not expected 

as a result of metrafenone use on grapes. Although the EU/UK formulation used in one of 

the studies closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not its 

equivalent. Therefore, the effect of the U.S. formulated product on vascular and nonvascular aquatic plants is not known.

2. Risk to Terrestrial Animals and Plants

a. Terrestrial Animals

1. Risk following acute exposure

Birds

The acute oral and dietary endpoints are both greater than the highest concentrations 

tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg diet, respectively). There were no 

mortalities or treatment related clinical signs of toxicity in the acute oral studies; one 

death in each dietary study was observed but was not considered treatment related. As a 

result, RQ values were not reported. Toxicity characterization implies that the technical is 

practically non-toxic. In addition, the highest concentration tested for the oral studies 

(2025 mg a.i./kg bw) is 7 times higher than the highest dose-based EEC (274.49 mg/kg) 

calculated from T-REX; meanwhile, the highest concentration tested for the dietary

studies (6070 mg a.i./kg diet) is 25 times higher than the highest dietary-based EEC 

(241.01 mg/kg). Therefore, given that comparison, acute risk to birds is not expected as a 

result of metrafenone use.

Potential risk to piscivorous birds

Several characteristics of metrafenone indicate that it has the potential to accumulate in 

tissues of aquatic organisms. The log of the n-octanol/water partition coefficient for 

metrafenone is 4.3 (at 25oC, pH 4). The lipid normalized BCF was determined to be 

between 140 and 530 (see MRID 47267450).

As stated in the risk estimation section, the acute oral and dietary endpoints are both 

greater than the highest concentrations tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg 

diet, respectively). There were no mortalities or treatment related clinical signs of toxicity

in the acute oral studies; one death in each dietary study was observed but was not 

considered treatment related. As a result, RQ values were not reported. The highest 

concentration tested for the oral studies (2025 mg a.i./kg bw) is 147 times higher than the 

 

8

See eastern oyster study (MRID 47267440)

9

See eastern oyster study (MRID 47267440)
Page 84 of 114

highest dose-based EEC (13.73 mg/kg bw/day) calculated from KABAM for birds 

consuming fish contaminated by metrafenone total residues; meanwhile, the highest 

concentration tested for the dietary studies (6070 mg a.i./kg diet) is 310 times higher than 

the highest dietary-based EEC (19.59 mg/kg). Therefore, given that comparison, acute 

risk to piscivorous birds is not expected due to consumption of fish contaminated with 

metrafenone.

Mammals

There were no mortalities in the acute oral rat study (MRID 47267609) on the 

formulation; one death was observed in the acute oral mouse study (MRID 47267522) on 

the technical active ingredient. Although the EU/UK formulation used in the formulation 

study closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not its 

equivalent. Therefore, the effect of the U.S. formulated product on mammals is not 

known. 

The acute endpoints for mammals are both greater than the highest concentrations tested 

(LD50: >2000 mg technical/kg bw, mouse; >5000 mg form/kg bw, rat). Therefore, RQ 

values were not reported. In the mouse study, only 3 individuals/sex were tested with 

mortality in 1/6 animals (17%). With a larger test sample, the LD50 could be approached. 

The toxicity classification implies that the technical is practically non-toxic to mice. In 

addition, the highest concentration tested for the oral study (2000 mg a.i./kg bw) is 9 

times higher than the highest dose-based EEC (229.78 mg/kg) calculated from T-REX. 

Therefore, given that comparison, acute risk to mammals is not expected as a result of 

metrafenone use.

Potential risk to piscivorous mammals

Risk to piscivorous mammals via consumption of fish contaminated with metrafenone 

was assessed because metrafenone has the potential to accumulate in tissues of aquatic 

organisms. 

As stated in the risk estimation section, there were no mortalities in the acute oral rat 

study (MRID 47267609) on the formulation and there was only one death in the acute 

oral mouse study (MRID 47267522) on the technical. Although the EU/UK formulation 

used in the formulation study matches the U.S. formulation (i.e., BAS 560 03F) it is still 

not its equivalent. Therefore, the effect of the U.S. formulated product on mammals is not 

known.

The highest concentration tested for the oral studies (2000 mg a.i./kg bw) is 257 times 

higher than the highest dose-based EEC (7.795 mg/kg bw/day) calculated from KABAM 

for mammals consuming fish contaminated by metrafenone total residues. Therefore, 

given that comparison, acute risk to piscivorous mammals is not expected due to 

consumption of fish contaminated with metrafenone.
Page 85 of 114

Terrestrial invertebrates

The 48-hour contact LD50 is >24.4 μg a.i./bee [>100 μg form/bee] with a NOAEC of 

<24.4 μg a.i./bee and a LOAEC of 24.4 μg a.i./bee based on mortality. Based on this 

toxicity data, metrafenone is classified as ‘practically non-toxic’ to honeybees on an 

acute contact basis. Thus, risk to honeybees is not expected as a result of direct contact 

with metrafenone. Similarly, the non-guideline earthworm studies consider metrafenone, 

its degradate, and a formulation to be non-lethal to earthworms up to a concentration of 

1000 mg a.i./kg dry soil, 1000 mg/kg dry weight of soil, and 1000 mg formulation/kg dry

soil, respectively. E. fetida is found in topsoil at depths of approximately 5-20cm. Given 

a soil depth of 20 cm and assuming a maximum application rate per season (1.8 lbs a.i./A, 

which assumes a hypothetical maximum active ingredient loading rate since the seasonal 

rate would not be applied all at once and likely degrade if applied in the recommended 6 

applications of at most 0.3 lbs a.i./A), the EEC is much lower (0.77 mg/kg soil) than the 

concentrations generated in these studies. At shallower depths (5 cm), the EEC is higher 

(3.08 mg/kg soil), but still lower than the study concentration (1000 mg a.i./kg soil). 

Therefore, risk to earthworms is not expected as a result of metrafenone use on grapes.

Although the EU/UK formulation used in the formulation studies for the bee and 

earthworm matches the U.S. formulation (i.e., BAS 560 03F) it is still not its equivalent.

Therefore, the effect of the U.S. formulated product on bees (and earthworms) is not 

known.

2. Risk following chronic exposure

Birds

The chronic avian dietary-based RQ does not exceed the chronic LOC for birds for any 

food catogory. The study (MRID 47267507) was done on mallard duck using the 

technical grade and yielded a definite endpoint based on egg production (eggs laid per 

female per week) and hatchability (% dead-in-shell of fertile eggs). Due to the fact that 

the RQ is only based on one bird species, there is an uncertainty associated with the 

estimated risk for all avian species. Nevertheless, given that LOCs were not exceeded,

chronic risk to birds is not expected as a result of metrafenone use on grapes.

Potential risk to piscivorous birds

As previously stated, risk to piscivorous birds via consumption of fish contaminated with 

metrafenone was assessed because metrafenone has the potential to accumulate in tissues 

of aquatic organisms. As stated in the risk estimation section, none of the RQs exceed 

the chronic LOC for birds. Therefore, chronic risk to piscivorous birds is not expected

due to consumption of fish contaminated with metrafenone total residues.

Mammals
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The chronic LOC is exceeded on a dose basis for mammals in all size classes eating short 

grass, for the 15 and 35 gram size classes eating tall grass and broadleaf plants / small 

insects. The chronic LOC on a dietary basis is not exceeded for any of the food 

categories. The study (MRID 46415729, 46415728) was done on the rat using the 

technical grade and yielded a definite endpoint based on decreased body weights and 

body weight gain in F1 males as well as body weights in F1 and F2 females. Due to the 

fact that the RQ is only based on one mammalian species, there is an uncertainty 

associated with the estimated risk for all mammals. Nevertheless, given the LOC 

exceedance chronic risk to mammals is expected as a result of metrafenone use. To 

reduce chronic risk to mammals, several components of the application protocol would 

have to change. For example, in order to have no chronic LOC exceedances (i.e., all RQs 

< 1) for mammals, the minimum single application rate (0.2 lbs a.i./A) would have to be 

cut by 25% (i.e., to 0.15 lbs a.i./A) yet considered the maximum instead, the application 

interval would have to nearly double (from 14 days up to 26 days), and the maximum 

allowed number of applications would have to be cut from 6 to 5. Alternatively, in order 

to have no chronic LOC exceedances for mammals, the minimum single application rate 

(0.2 lbs a.i./A) can still be applied yet considered the maximum instead, but the 

application interval would have to nearly double (from 14 days up to 26 days), and the 

maximum number of applications would have to be cut by 50% (i.e., from 6 to 3).

Furthermore, in order to have no chronic LOC exceedances in nearly all cases for 

mammals –the one exception being an exceedance for the 15g size glass consuming short 

grass where the calculated RQ is 1.02 – the minimum single application rate (0.2 lbs 

a.i./A) would be changed to the maximum single application rate and the application 

interval (14 days) could remain as currently prescribed by the label, but the maximum 

number of applications would have to be reduced from 6 to 2.

Potential risk to piscivorous mammals

As previously stated, risk to piscivorous mammals via consumption of fish contaminated 

with metrafenone was assessed because metrafenone has the potential to accumulate in 

tissues of aquatic organisms. As stated in the risk estimation section, none of the RQs 

exceed the chronic LOC for mammals. Therefore, chronic risk to piscivorous mammals 

is not expected due to consumption of fish contaminated with metrafenone.

b. Terrestrial Plants

As stated in the risk estimation section, terrestrial plant risk quotients were not calculated 

on account of indeterminate endpoints generated in both the seedling emergence and 

vegetative vigor studies. The lower application rates in the studies (0.091 and 0.288 lbs 

a.i./A for the seedling emergence study; and, 0.091 and 0.285 lbs a.i./A for all but 

soybean [0.099 and 0.283 lbs a.i./A] for the vegetative vigor study) relative to the label 

application rate (0.3 lbs a.i./A) leads to uncertainty in the risk characterization especially 

as effects were noted. However, the effects in both studies are not considered significant 

and the NOAEC and EC05 are undefined (seedling emergence: NOAEC 0.288 lbs a.i./A; 

EC05, EC25 > 0.288 lbs a.i./A; vegetative vigor: NOAEC 0.285 lbs a.i./A; EC05, EC25 > 
Page 87 of 114

0.285 lbs a.i./A10). Consequently, the most sensitive monocot and dicot species could not 

be determined from either study. Hypothetically, had the NOAEC been determined to be 

0.091 lbs a.i./A (the lower concentration tested) in both the vegetative vigor and seedling 

emergence studies and given the maximum single application rate (0.3 lbs a.i./A), the risk 

would not have triggered concern for either the dicot or monocot species. In addition, the 

EECs based on the maximum seasonal application rate (1.8 lbs a.i./A) range from 0.018 –

0.198 lbs a.i./A, which are below the concentrations tested in these studies. Since effects 

were not significant at the test concentrations, which are higher than the calculated EECs, 

risk to terrestrial plants is not expected as a result of use of the EU/UK formulation. Both 

studies were conducted on the EU/UK formulation (BAS 560 00F); therefore, uncertainty 

exists in determining risk to the U.S. formulation (BAS 560 03F). Tier II tests are

requested to better define the toxicity endpoints, to have a study available that is based on 

the U.S. formulation, and, subsequently, reduce uncertainty in risk characterization.

3. Review of Incident Data

With the proposed use on grapes, metrafenone will be applied in the United States for the 

first time. Therefore, no incident data are available at this time. 

4. Endocrine Effects

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the 

Administrator may designate.” The EDSP employs a two-tiered approach to making the 

statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to 

identify the potential of a chemical substance to interact with the estrogen, androgen, or 

thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and 

are found to have the potential to interact with E, A, or T hormonal systems will proceed 

to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests 

are necessary based on the available data. Tier 2 testing is designed to identify any

adverse endocrine related effects caused by the substance, and establish a dose-response 

relationship between the dose and the E, A, or T effect.

Between October 2009 and February 2010, EPA is issuing test orders/data call-ins for the 

first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert 

ingredients. This list of chemicals was selected based on the potential for human 

exposure through pathways such as food and water, residential activity, and certain postapplication agricultural scenarios. This list should not be construed as a list of known or 

likely endocrine disruptors.

 

10 Applicable to all dicot (and monocot) species except for the soybean for which the endpoints are 

NOAEC 0.283 lbs a.i./A and EC05, EC25 > 0.283 lbs a.i./A in the vegetative vigor study only.
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Metrafenone is not among the group of 58 pesticide active ingredients on the initial list to 

be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all 

pesticide chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data 

call-ins for all pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/.

5. Federally Threatened and Endangered (Listed) Species

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2), requires all 

federal agencies to consult with the National Marine Fisheries Service (NMFS) for 

marine and anadromous listed species, or the United States Fish and Wildlife Services 

(FWS) for listed wildlife and freshwater organisms, if they are proposing an "action" that

may affect listed species or their designated habitat. Each federal agency is required 

under the Act to insure that any action they authorize, fund, or carry out is not likely to 

jeopardize the continued existence of a listed species or result in the destruction or 

adverse modification of designated critical habitat. To jeopardize the continued existence 

of a listed species means "to engage in an action that reasonably would be expected, 

directly or indirectly, to reduce appreciably the likelihood of both the survival and 

recovery of a listed species in the wild by reducing the reproduction, numbers, or 

distribution of the species" (50 C.F.R. § 402.02).

To facilitate compliance with the requirements of the Endangered Species Act 

(subsection (a)(2)), the Office of Pesticide Programs has established procedures to 

evaluate whether a proposed registration action may directly or indirectly reduce 

appreciably the likelihood of both the survival and recovery of a listed species in the wild 

by reducing the reproduction, numbers, or distribution of any listed species (USEPA, 

2004). After the Agency’s screening level risk assessment is conducted, if any of the 

Agency’s listed species LOCs are exceeded for either direct or indirect effects, an 

analysis is conducted to determine if any listed or candidate species may co-occur in the 

area of the proposed pesticide use or areas downstream or downwind that could be 

contaminated from drift or runoff/erosion. If listed or candidate species may be present 

in the proposed action areas, further biological assessment is undertaken. The extent to 

which listed species may be at risk then determines the need for the development of a 

more comprehensive consultation package as required by the Endangered Species Act.

Both acute endangered species and chronic risk LOCs are considered in the screeninglevel risk assessment of pesticide risks to listed species. Endangered species acute LOCs 

are a fraction of the non-endangered species LOCs or, in the case of endangered plants, 

RQs are derived using lower toxicity endpoints than non-endangered plants. Therefore, 

concerns regarding listed species within a taxonomic group are triggered in exposure 

situations where restricted use or acute risk LOCs are triggered for the same taxonomic 

group. The risk assessment also includes an evaluation of the potential probability of 

individual effects for exposures that may occur at the established endangered species 
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LOC both in the risk characterization and the endangered species sections. This 

probability is calculated using the established dose/response relationship and assumes a 

probit (probability unit) dose/response relationship. 

a. Action Area

For listed species assessments, the action area is considered to be the area affected 

directly or indirectly by the Federal action and not merely the immediate area where 

metrafenone is applied. At the initial Level 1 screening assessment, broadly described 

taxonomic groups are considered, and thus, conservatively assumes that listed species 

within those broad groups are co-located with 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 listed species are located within the 

area of highest exposure to the pesticide, and that exposure will decrease with increasing 

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, a "no effect" determination conclusion is made with 

respect to listed species in that taxa, and no further refinement of the action area 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 covered by the RQ 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 for a "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 upon that taxonomic group as a resource. 

In such cases, additional information on the biology of 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.

b. Taxonomic Groups Potentially at Risk

The preliminary risk assessment for endangered species indicates that the proposed use 

and application rate for metrafenone either exceeds the Endangered Species LOCs for the 

following taxonomic groups (underlined [chronic exposure to mammals]) or those for 

which risk cannot be precluded (also underlined [chronic exposure to freshwater fish and 

invertebrates, acute exposure to marine/estuarine invertebrate, chronic exposure to 

marine/estuarine fish]).
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 Chronic exposure to mammals

 Data was not submitted or was deemed invalid for the following: chronic 

exposure to freshwater invertebrates and marine/estuarine fish. A 

passerine bird study is also not available at this time. Lack of data does not 

preclude risk.

 Data was supplemental, but inadequate for risk quotient calculations 

which would have helped to determine risk to endangered species for the 

following: acute exposure to freshwater fish and invertebrates, acute 

exposure to marine/estuarine invertebrates, chronic exposure to freshwater 

fish; and, aquatic plants. Therefore, there is uncertainty in determining risk 

to these taxonomic groups. However, the total concentration based 

endpoint (EC50: 0.22 mg total a.i./L) for the acute marine/estuarine 

invertebrate (eastern oyster) study (MRID 47267440) with an effect on 

shell deposition is 11x greater than the highest estimated EEC (0.02 

mg/L), hence risk to federally listed marine/estuarine invertebrates cannot 

be precluded. The total concentration based endpoint (NOAEC: 0.118 mg 

total a.i./L) for the chronic freshwater fish (fathead minnow) study (MRID 

47267449) with an effect on post-hatch survival is approximately 7x 

greater than the highest estimated EEC (0.016 mg/L), hence risk to 

federally listed freshwater fish cannot be precluded. Applying similar 

calculations to the acute freshwater fish and invertebrate data as well as

data for aquatic plants assumes low risk to federally listed species.

 Data was acceptable, but inadequate for risk quotient calculations for the 

following: acute exposure to marine/estuarine fish. Therefore, there is 

uncertainty in determining risk to these taxonomic groups. The highest 

concentration tested in the acute marine/estuarine fish (sheepshead 

minnow) study (MRID 47267446) was 0.35 mg dissolved a.i./L which is 

17.5x greater than the highest estimated EEC (0.02 mg/L) but there were 

no effects on mortality or sublethal effects, hence risk to federally listed 

marine/estuarine fish is assumed to be low. Acceptable data for acute 

exposure to birds yields non-definitive endpoints with no effects; 

therefore, acute risk to federally listed birds is expected to be low. For 

similar reasons, acute risk to federally listed piscivorous birds, mammals, 

and piscivorous mammals is also expected to be low.
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Concerns For Federally Listed as Endangered and/or Threatened Species

Table 35. Listed Species Risks Associated with Direct or Indirect Effects from Metrafenone 

use on Grapes at the Maximum Proposed Application Rate (0.3 lbs a.i./A, Assuming 6 

Applications/Year)

Listed Taxon Direct Effects Indirect Effects

Terrestrial and semi-aquatic plants - monocots No Yes from effects to mammals

Terrestrial and semi-aquatic plants – dicots No Yes from effects to mammals

Terrestrial invertebrates No Yes from effects to mammals

Birds No Yes from effects to mammals,

FW fish, FW inverts, M/E fish,

M/E inverts (mollusks)

Terrestrial-phase amphibians No Yes from effects to mammals

Reptiles No Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Mammals Yes for chronic1 Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

 Aquatic non-vascular plants No Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Aquatic vascular plants No Yes from effects to mammals,

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Freshwater (FW) fish Yes for chronic2 Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Aquatic-phase amphibians Yes for chronic3 Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Freshwater (FW) invertebrates Yes for chronic4 Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Marine/estuarine (M/E) fish Yes for chronic4 Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

Marine/estuarine (M/E) invertebrates (mollusk) Yes for acute5,

No for chronic6

Yes from effects to mammals, 

FW fish, FW inverts, M/E fish, 

M/E inverts (mollusks)

1 The chronic LOC is exceeded on a dose basis for mammals in all size classes eating short grass, for the 15 and 35 

gram size classes eating tall grass and broadleaf plants / small insects. The chronic LOC on a dietary basis is not 

exceeded for any of the food categories. 

2 The total concentration based endpoint (NOAEC: 0.118 mg total a.i./L) for the chronic freshwater fish (fathead 

minnow) study (MRID 47267449) with an effect on post-hatch survival is approximately 7x greater than the highest 

estimated EEC (0.016 mg/L), hence risk to federally listed freshwater fish cannot be precluded.

3 Results from freshwater fish used as surrogate for assessing risk to aquatic-phase amphibians

4

Studies not submitted or invalid for which risk cannot be precluded.

5 Mollusk (Eastern oyster); 6

Saltwater mysid
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1. Discussion of risk quotients

The Agency’s LOCs for mammals (chronic) are exceeded for the use of metrafenone on 

grapes as outlined in previous sections. The risk to the remaining federally listed 

taxonomic groups (freshwater fish and invertebrates (chronic), marine/estuarine 

invertebrate (acute), marine/estuarine fish (chronic)) cannot be precluded on the basis of 

toxicity data and estimated exposures. Should estimated exposure levels occur in 

proximity to listed resources, the available screening level information suggests a 

potential concern for direct effects on listed species within the taxonomic groups listed 

above associated with the uses of metrafenone as described in Section III.A. The 

registrant must provide information on the proximity of federally listed mammals, 

freshwater fish and invertebrates, as well as marine/estuarine fish and invertebrates to the 

metrafenone use sites. This requirement may be satisfied in one of three ways: 1) having 

membership in the FIFRA Endangered Species Task Force (Pesticide Registration [PR] 

Notice 2000-2); 2) citing FIFRA Endangered Species Task Force data; or 3) 

independently producing these data, provided the information is of sufficient quality to 

meet FIFRA requirements. The information will be used by the OPP Endangered Species 

Protection Program to develop recommendations to avoid adverse effects to listed 

species.

2. Probit dose response relationship

The Agency uses the probit dose response relationship as a tool for providing additional 

information on the potential for acute direct effects to aquatic and terrestrial animals 

(U.S. EPA, 2004). As part of the risk characterization, an interpretation of acute RQ for 

listed species is discussed. This interpretation is presented in terms of the chance of an 

individual event (i.e., mortality or immobilization) should exposure at the EEC actually

occur for a species with sensitivity to metrafenone on par with the acute toxicity endpoint 

selected for RQ calculation. To accomplish this interpretation, the Agency uses the slope 

of the dose response relationship available from the toxicity study used to establish the 

acute toxicity measures of effect for each taxonomic group that is relevant to this 

assessment. The individual effects probability associated with the acute RQ is based on 

the mean estimate of the slope and an assumption of a probit dose response relationship. 

In addition to a single effects probability estimate based on the mean, upper and lower 

estimates of the effects probability are also provided to account for variance in the slope, 

if available. The upper and lower bounds of the effects probability are based on available 

information on the 95% confidence interval of the slope. Studies with good probit fit 

characteristics (i.e., statistically appropriate for the data set) are associated with a high 

degree of confidence. Conversely, a low degree of confidence is associated with data 

from studies that do not statistically support a probit dose response relationship. In 

addition, confidence in the data set may be reduced by high variance in the slope (i.e., 

large 95% confidence intervals), despite good probit fit characteristics. In the event that 

dose response information is not available to estimate a slope, a default slope assumption 

of 4.5 (95% C.I.: 2 to 9) (Urban and Cook, 1986) is used. 
Page 93 of 114

Individual effect probabilities are calculated based on an Excel spreadsheet tool IEC v1.1 

(Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP, 

Environmental Fate and Effects Division (June 22, 2004). The model allows for such 

calculations by entering the mean slope estimate (and the 95% confidence bounds of that 

estimate) as the slope parameter for the spreadsheet. In addition, the acute RQ is entered 

as the desired threshold. However, on account of either non-definitive acute endpoints or 

endpoints based on total concentrations (dissolved + undissolved test compound) instead 

of dissolved concentrations only, the acute studies which would otherwise be useful for 

calculating individual effect probabilities cannot be used.

3. Data related to under-represented 

taxa

Effects data on under-represented taxonomic groups were not submitted by the 

Registrant. Effects data from other analyzed sources were either not obtained (ECOTOX 

Database, PAN Database) or were not available (publicly available ECOTOX) for this 

screening risk assessment. 

4. Implications of sublethal effects

For the sublethal effects discussed below, it is noted that EFED cannot quantitatively

assess the relationship between any of the observed sublethal effects and potential 

reduction in survival or reproductive impairment at this time. Instead, the concentrations 

at which sublethal effects were observed in laboratory studies are discussed in relation to 

the concentrations at which mortality and/or reproductive effects were observed in the 

same laboratory studies and compared to aquatic and terrestrial EECs and assessed as to 

whether or not they may be expected under field conditions. The EU/UK formulation 

(BAS 560 00F), which is used in all formulation studies, closely matches the U.S. 

formulation (i.e., BAS 560 03F) but is not equivalent. The formulation studies are cited 

and evaluated in this assessment. However, at this time, the effect of the U.S. formulation 

on any given taxa is not known.

Acute Studies

Aquatic Organisms

The greatest amount of uncertainty in the assessment stems from aquatic studies which 

were largely based on total concentrations (both dissolved and undissolved) instead of the 

soluble concentrations of the test compound.

Given the freshwater fish acute toxicity data the bluegill sunfish (Lepomis macrochirus) 

appears to be more sensitive than the rainbow trout (Oncorhynchus mykiss) on the 

technical grade active ingredient. Sublethal effects (lethargic and motionless fish) were 

observed in the bluegill study at the highest concentration tested (0.87 mg total a.i./L) 
Page 94 of 114

which is greater than the peak aquatic EEC (0.02 mg a.i./L). Similarly, the lowest tested 

metabolite concentration at which sublethal effects were observed for the trout study was 

at 20.3 mg total a.i./L, which is also below the total metrafenone residue peak EEC. The 

numbers imply that sublethal effects on freshwater fish due to the parent or metabolite of 

metrafenone are not expected under field conditions. 

The freshwater invertebrate study on daphnia using the technical grade active ingredient 

and a metabolite (CL 375816) indicated no effects. On the other hand, another metabolite 

study (using CL 4084564) indicated immobility at 23.2 mg total a.i./L, which is also 

above peak EEC levels. The numbers imply that sublethal effects on freshwater 

invertebrates due to the parent or metabolite of metrafenone are not expected under field 

conditions. 

No effects were observed for the marine/estuarine fish technical grade active ingredient 

study. Erratic swimming was observed in the saltwater mysid (Americamysis bahia) 

study at 0.416 mg total a.i./L and mortality at 0.129 mg total a.i./L, which are again 

above peak EEC levels. Therefore, the values imply that sublethal effects on 

marine/estuarine fish and invertebrates due to the parent metrafenone are not expected 

under field conditions. 

Terrestrial Organisms

The acute oral avian studies indicated no effects; the acute dietary avian studies indicated 

a significant change in body weight that was not associated with a dose-response pattern. 

In the mammal study on the technical grade active ingredient, only mortality was 

reported. Therefore, no implications with sublethal effects can be made.

Chronic Studies

Aquatic Organisms

The freshwater fish chronic toxicity endpoint (NOAEC 0.118 mg total a.i./L) based on 

post-hatch is greater than the highest chronic EEC (0.017 mg a.i./L). Similarly, the 

marine/estuarine invertebrate chronic toxicity endpoint (NOAEC 0.022 mg a.i./L) based 

on reproduction is greater than the highest chronic EEC (0.018 mg a.i./L). The values 

imply that chronic effects on freshwater fish and marine/estuarine invertebrates are not 

expected under field conditions. 

No acceptable chronic freshwater invertebrate studies are available. No chronic 

marine/estuarine fish studies were submitted for review. 

Terrestrial Organisms

The avian chronic toxicity endpoint (NOAEC 848 mg a.i./kg diet) based on egg 

production and hatchability did not yield chronic LOC exceedances. The most sensitive 

chronic mammalian endpoint (NOAEL 35.9 mg/kg bw/day) based on decreased body 
Page 95 of 114

weights and body weight gain in F1 males as well as body weights in F1 and F2 females, 

however, exceeded the chronic LOC, which implies that sublethal chronic effects on 

mammals are expected under field conditions. 

c. Indirect Effects Analysis

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. The listed species rely upon non-listed organisms in these taxonomic groups as 

resources critical to their life 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. 

However, there may be situations where a taxonomic group is not quantitatively assessed 

(e.g., terrestrial insects), but other lines of evidence are sufficiently supportive of 

concerns for indirect effects on listed organisms that are dependant upon that taxonomic 

group.

· Where One or More Animal Taxonomic Group RQs Exceed the LOC for 

Listed Species 

The Level I screening indirect effects analysis documents those types of dependencies 

upon non-listed organisms that could be important sources of indirect effects to listed 

organisms should effective levels of the pesticide coincide with locations of listed species 

and the biologically based resources upon which they depend. In cases where screeninglevel acute RQs for a given animal group equal or exceed the endangered species acute 

LOC, the Agency uses the dose response relationship from the toxicity study used for 

calculating the RQ to estimate the probability of acute effects associated with an 

exposure equivalent to the EEC. This information serves as a guide to establish the need 

for and extent of additional analysis that may be performed using Services-provided 

“species profiles” as well as evaluations of the geographical and temporal nature of the 

exposure to ascertain if a not likely to adversely affect determination can be made. The 

degree to which additional analyses are performed is commensurate with the predicted 

probability of adverse effects from the comparison of dose response information with the 

EECs. The greater the probability that exposures will produce effects on a taxa, the 

greater the concern for potential indirect effects for listed species dependant upon that 

taxa, and therefore, the more intensive the analysis on the potential listed species of 

concern, their locations relative to the use site, and information regarding the use scenario 

(e.g., timing, frequency, and geographical extent of pesticide application). The greatest 

concerns would exist when exposure is associated with a risk higher than the effects 

probability associated with the non-endangered LOC for a pesticide with an average 

slope of 4.5. 

For metrafenone, risks to listed species are predicted within the following taxa: 

mammals, freshwater fish and invertebrates, marine/estuarine invertebrates, and 

marine/estuarine fish. Changes in fish and aquatic invertebrate populations could 

indirectly affect other fish and aquatic invertebrates, aquatic plants, birds, reptiles and 
Page 96 of 114

mammals. The chronic endpoint for mammalian species is based on decreases in body

weight and/or body weight gain in both the parents and pups. If body size following 

chronic metrafenone exposure is reduced to the extent that it has an impact on 

mammalian populations, reduction in mammalian populations that are used as a resource 

for listed species may be of concern. Given that the chronic LOC is exceeded for 

mammals, indirect effects to listed species (e.g., other mammals, birds, amphibians, 

reptiles, plants (pollination) and terrestrial invertebrates) that rely on mammals as a 

primary food source, or on mammal burrows for shelter or breeding habitat, may be of 

concern. 

d. Critical Habitat

In the evaluation of pesticide effects on designated critical habitat, consideration is given 

to the physical and biological features (constituent elements) of a critical habitat 

identified by the U.S Fish and Wildlife and National Marine Fisheries Services as 

essential to the conservation of a listed species and which may require special 

management considerations or protection. The evaluation of impacts for a screening 

level pesticide risk assessment focuses on the biological features that are constituent 

elements and is accomplished using the screening-level taxonomic analysis (risk 

quotients, RQs) and listed species levels of concern (LOCs) that are used to evaluate 

direct and indirect effects to listed organisms.

The screening-level risk assessment has identified potential concerns for indirect effects 

on listed species for those organisms dependant upon mammals, freshwater fish and 

invertebrates, marine/estuarine invertebrates, and marine/estuarine fish. In light of the 

potential for indirect effects, the next step for EPA and the Service(s) is to identify which 

listed species and critical habitat are potentially implicated. Analytically, the 

identification of such species and critical habitat can occur in either of two ways. First, 

the agencies could determine whether the action area overlaps critical habitat or the 

occupied range of any listed species. If so, EPA would examine whether the pesticide's 

potential impacts on non-endangered species would affect the listed species indirectly or 

directly affect a constituent element of the critical habitat. Alternatively, the agencies 

could determine which listed species depend on biological resources, or have constituent 

elements, that fall into the taxa that may be directly or indirectly impacted by the 

pesticide. Then EPA would determine whether use of the pesticide overlaps the critical 

habitat or the occupied range of those listed species. At present, the information 

reviewed by EPA does not permit use of either analytical approach to make a definitive 

identification of species that are potentially impacted indirectly or critical habitat that is 

potentially impacted directly by the use of the pesticide. EPA and the Service(s) are 

working together to conduct the necessary analysis.

This screening-level risk assessment for critical habitat provides a listing of potential 

biological features that, if they are constituent elements of one or more critical habitats, 

would be of potential concern. These correspond to the taxonomic groups identified 

above as being of potential concern for indirect effects (i.e., mammals, freshwater fish 

and invertebrates, marine/estuarine invertebrates, and marine/estuarine fish). This should 
Page 97 of 114

serve as an initial step in problem formulation for further assessment of critical habitat 

impacts outlined above, should additional work be necessary.

e. Co-occurrence Analysis

The goal of the analysis for co-location is to determine whether sites of pesticide use are 

geographically associated with known locations of listed species. At the screening level, 

this analysis is accomplished using the LOCATES v. 2.10.4 database. The database uses 

location information for listed species at the county level and compares it to agricultural 

census data for crop production at the same county level of resolution. The product is a 

listing of federally listed species that are located within counties known to produce the 

crop upon which the pesticide will be used. 

Tables 36 and 37 below report the number of states and counties in which endangered 

species reside that have the proposed metrafenone use. The ‘grape’ category was selected 

in LOCATES. The data suggest that there is considerable potential for exposure to a 

variety of endangered species from metrafenone use. For additional LOCATES output 

refer to Appendix E.

Species Counts by State for Indicated Crops

No species were excluded.

Minimum of 1 Acre.

All Medium Types Reported

grapes

AL, AK, AZ, AR, CA, CO, CT, DE, DC, FL, GA, HI, ID, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, 

MN, MS, MO, MT, NE, NV, NH, NJ, NM, NY, NC, ND, OH, OK, OR, PA, PR, RI, SC, SD, TN, TX, 

UT, VT, VA, WA, WV, WI, WY

Table 36. Number of Endangered Species Potentially Exposed to Metrafenone with the Proposed Uses

Mammals Amphibians Birds Reptiles Arachnids Insects Conf/Cyc Dicot Ferns Lichen Monocots

Counties 744 93 595 231 12 153 6 493 28 14 272

States 47 11 43 24 4 28 3 41 8 4 37

Species 129 21 163 74 13 73 4 607 20 4 109

Table 37. Number of Endangered Species Potentially Exposed to 

Metrafenone with the Proposed Uses

Bivalve Crustacean Fish Gastropod Marine Mammal

Counties 290 56 449 44 50

States 27 13 38 16 7

Species 205 21 197 32 10
Page 98 of 114

C. Description of Assumptions, Limitations, Uncertainties, Strengths, and Data 

Gaps

1. Assumptions, Limitations, and Uncertainties Related to 

Exposure for all Taxa

a. Maximum Use Scenario

The screening-level risk assessment focuses on characterizing potential ecological risks 

resulting from a maximum use scenario, which is determined from labeled statements of 

maximum application rate and number of applications with the shortest time interval 

between applications. The frequency at which actual uses approach this maximum use 

scenario may be dependant on fungicide resistance, timing of applications, cultural 

practices, and market forces. 

2. Assumptions, Limitations, and Uncertainties Related to 

Exposure for Aquatic Species

a. Environmental Fate Studies

All of the environmental fate studies for the parent compound were determined to be 

scientifically valid and therefore results from all of the studies can be used to characterize 

the mobility and rates of transformation of metrafenone. However, many of the 

metabolism studies have major uncertainties in the identification and pattern of formation 

and decline of transformation products. In all of the aquatic metabolism studies, between 

57% and 65% of the applied radioactivity remains unidentified with incomplete 

characterization, and in two aerobic soil metabolism studies, 15% and 44% of the applied 

radioactivity is unidentified. This includes at least four major degradates that 

individually reach levels of 11% to 35% of the applied. Other transformation products 

appear as groups of up to 15 components, in some cases characterized as each being <5% 

of the applied radioactivity, but in other cases, some individual components make up 9% 

to 10% of the applied. Even when individual components can all be classified as minor 

degradates, these groups represent such a large portion of the applied radioactivity overall 

that the possibility that they may have some impact as a group cannot be precluded 

despite their lower individual levels. This is especially true given that the degradation 

pathways suggest that groups of degradates may have a high degree of structural 

similarity and so may have similar fate and effects behavior. Without information to 

adequately characterize the degradates, it may be necessary to assume that they are of 

equal toxicity to the parents in order to quantify risks.

b. Aquatic Exposure Modeling

The lack of complete characterization and identification of degradation products 

prompted additional aquatic exposure modeling on total metrafenone residues. Although 

this modeling approach is conservative, it is reasonable modeling approach to address 

uncertainties in degradation product identification.
Page 99 of 114

c. Bioaccumulation Modeling

Bioaccumulation modeling was conducted because metrafenone has a log Kow > 4. The 

bioaccumulation modeling was conducted using guidance for the KABAM model. It is 

recommended to report the sediment pore water and water column concentrations at the 

appropriate time when the pesticide concentration reaches steady-state. An evaluation of 

the time series for metrafenone showed no clear plateau in metrafenone concentrations. 

Therefore, the appropriate averaging time was selected at 21 days to serve as a 

conservative exposure concentration for bioaccumulation modeling. 

3. Assumptions, Limitations, and Uncertainties Related to 

Exposure for Terrestrial Species

a. Location of Wildlife Species

For this screening-level terrestrial risk assessment, a generic bird or mammal was 

assumed to occupy either the treated field or adjacent areas receiving metrafenone at the 

treatment rate on the field. Actual habitat requirements of any particular terrestrial 

species were not considered, and it was assumed that species occupy, exclusively and 

permanently, the modeled treatment area. Spray drift model predictions suggest that this 

assumption leads to an overestimation of exposure to species that do not occupy the 

treated field exclusively and permanently.

b. Routes of Exposure

This screening-level assessment for ground (liquid) applications of metrafenone only

considered dietary exposure. Other routes of exposure that were not considered in the 

assessment are incidental soil ingestion exposure, inhalation exposure, dermal exposure, 

and drinking water exposure.

c. Dietary Intake and Other Limitations of Oral 

Studies in Terrestrial Species

The avian acute oral study and the avian subacute dietary study each have limitations for 

estimating the risk to wild species exposed to pesticides in the environment. Both studies 

have a fixed exposure period and do not allow for differences in the responses of 

individuals to different durations of exposure. With the acute oral study, the chemical is 

administered in a single dose. This does not mimic wild bird exposure through multiple 

feedings. Also, it does not account for the effect of different environmental matrices on 

absorption rate into the gastrointestinal tract of the animal. With the acute dietary study, 

the endpoint is reported as the concentration mixed with food that produces a response 

rather than as the dose ingested. Although food consumption sometimes allows for 

estimation of a dose, calculations of the mg/kg/day are confounded by undocumented 

spillage of feed and how consumption is measured over the duration of the test. Usually, 

if measured at all, food consumption is estimated once at the end of the five-day exposure 
Page 100 of 114

period. Group housing of birds undergoing testing allows for a measure of only the 

average consumption per day for a group, and consumption estimates can be further 

confounded if birds die within a treatment group. In addition, the dietary study utilizes 

young birds. The exponential growth of young birds complicates the estimate of the 

dose; controls often nearly double in size over the duration of the test. Since weights are 

only taken at the initiation and at the end of the exposure period, the dose per body

weight (mg/kg) is difficult to estimate with any precision. The interpretation of this test 

can be further confounded by dietary consumption. Estimation of the acute LC50 value is 

not only a function of the intrinsic toxicity of the pesticide, but also the willingness of the 

birds to consume treated food. 

In addition to the uncertainties associated with the two toxicity studies utilized for 

estimating acute risk to birds, other factors, not normally taken into account in a 

screening level risk assessment may narrow the differences between the dose-based and 

dietary-based acute RQs for birds. The factors include differences in gross energy and 

assimilative efficiency of laboratory feed versus food items in the field, basic 

maintenance metabolic rates between wild birds and captive birds, seasonal free living 

dietary requirements for wild birds (including gorging behavior) and specific food 

avoidance behavior. These uncertainties may either overestimate or underestimate the 

risk in a screening level assessment.

Gross Energy and Assimilative Efficiency. This screening level risk assessment does 

not allow for gross energy and assimilative efficiency differences between wildlife food 

items and laboratory feed. For example, a typical laboratory avian feed, as used, contains 

approximately 2750 kcal/ kg. The Agency’s Wildlife Exposure Factors Handbook (U.S. 

Environmental Protection Agency, 1993) presents the following dry-weight and fresh 

weight caloric contents for selected wildlife food items:

Food Item Energy Dry (kcal/kg) Energy Fresh 

(kcal/kg)

grasses 4200 1300

broadleaf forage 4200 2200

seeds 5100 4700

fruits 2000 1100

insects 5600 1600

On gross energy content alone, direct comparison of a laboratory dietary concentrationbased effects threshold to a fresh-weight pesticide residue estimate would result in an 

underestimation of field exposure by food consumption by a factor of 1.25 - 2.5 for most 

food items. Only for seeds would the direct comparison of dietary threshold to residue 

estimate lead to an overestimate of exposure.

Depending upon species and dietary matrix, bird assimilation of wild diet energy ranges 

from 23 - 80%, and mammal’s assimilation ranges from 41 - 85% (U.S. EPA, 1993). If it 

is assumed that laboratory chow is formulated to maximize assimilative efficiency (e.g., a 

value of 85%), a potential for underestimation of exposure may exist by assuming that 
Page 101 of 114

consumption of food in the wild is comparable with consumption during laboratory

testing.

Metabolic Rates. In the screening process, exposure may be underestimated because 

metabolic rates are not related to food consumption. For example, the Wildlife Exposure 

Factors Handbook (U.S. EPA, 1993) includes allometric models for estimating both 

existing metabolic rate (EMR) and free living metabolic rate (FMR). EMR is the 

metabolic rate necessary for animal maintenance in captivity without body weight loss, a 

condition similar to caged test animals. FMR is the energy requirement for an organism 

in the wild. For passerine birds these relationships are as follows:

EMR (kcal/day) = 1.572 (body weight g) 0.6210

FMR (kcal/day) = 2.123 (body weight g) 0.749

Using a weight range for passerines of 10 - 150 g, the EMR predictions range from 6.6 to 

35.3, and the FMR ranges from 11.9 to 90.5 kcal/day. Thus, it appears that not 

accounting for increased energy demands of organisms in the wild when comparing 

dietary residues to dietary toxicity thresholds represents about a two-fold underestimation 

in exposure potential.

Free Living Metabolic Requirements. The screening procedure does not account for 

situations where the feeding rate may be above or below requirements to meet free living 

metabolic requirements. Gorging behavior is a possibility under some specific wildlife 

scenarios (e.g., bird migration) where the food intake rate may be greatly increased. 

Kirkwood (1983) has suggested that an upper-bound limit to this behavior might be the 

typical intake rate multiplied by a factor of 5. 

Avoidance. In contrast is the potential for avoidance, operationally defined as animals 

responding to the presence of noxious chemicals in their food by reducing consumption 

of treated dietary elements. This response is seen in nature where herbivores avoid plant 

secondary compounds. For agrochemicals, Dolbeer et al. (1994) reported that the use of 

methiocarb on fruit crops reduced depredation by birds. Of course, chemical treatment of 

food sources and any subsequent avoidance of those food sources by a species may, in 

itself, result in detrimental effects on the energetics of the species.

d. Incidental Releases Associated with Use

This risk assessment was based on the assumption that the entire treatment area is subject 

to pesticide application at the rates specified on the label. Uneven application of the 

pesticide through 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 were not accounted for in this assessment.
Page 102 of 114

e. Residue Levels Selection

The Agency relies on the work of Fletcher et al. (1994) for setting the assumed pesticide 

residues in wildlife dietary items. These residue assumptions are believed to reflect a 

realistic upper-bound residue estimate, although the degree to which this assumption 

reflects a specific percentile estimate is difficult to quantify. It is important to note that 

the field measurement efforts used to develop the Fletcher estimates of exposure involve 

highly varied sampling techniques. It is entirely possible that much of these data reflects 

residues averaged over the entire above ground plants in the case of grass and forage 

sampling. Depending upon a specific wildlife species’ foraging habits, whole 

aboveground plant samples may either underestimate or overestimate actual exposure.

f. TerrPlant Model

At this time, the TerrPlant model cannot accurately estimate terrestrial exposure levels 

with pesticides applied with multiple applications or application intervals. The 

technology is not yet available for these types of estimations. The label states that a 

maximum of 1.8 lbs a.i./A may be applied per season, with a maximum of six 

applications the highest single application rate is 0.3 lbs a.i./A. In modeling the terrestrial 

EECs, it was assumed that there was one application per year. If assuming one 

application of 1.8 lbs a.i./A the RQ values may be considered an overestimate of risk, but 

assuming one application of 0.3 lbs a.i./A the RQ values may be considered an 

underestimate of risk. Therefore, the model was used to bracket the potential risk on 

terrestrial plants as a result of metrafenone use.

4. Assumptions, Limitations, and Uncertainties Related to 

Effects Assessment

a. Sublethal Effects

For an acute risk assessment, the screening risk assessment relies on the acute mortality

endpoint as well as a suite of sublethal responses to the pesticide, as determined by the 

testing of species response to chronic exposure conditions and subsequent chronic risk 

assessment. Consideration of additional sublethal data in the assessment is exercised on a 

case-by-case basis and only after careful consideration of the nature of the sublethal 

effect measured and the extent and quality of available data to support establishing a 

plausible relationship between the measure of effect (sublethal endpoint) and the 

assessment endpoints.

b. Age Class and Sensitivity of Effects Thresholds

Testing of juvenile organisms may overestimate toxicity at older age classes for pesticidal 

active ingredients that act directly (without metabolic transformation) because younger 

age classes may not have the enzymatic systems associated with detoxifying xenobiotics. 

However, the influence of age may not be uniform for all compounds, and compounds 
Page 103 of 114

requiring metabolic activation may be more toxic in older age classes. The risk 

assessment uses the most sensitive life-stage information as the conservative screening 

endpoint.

c. Use of Most Sensitive Species Tested

Screening risk assessment relies on a selected toxicity endpoint from the most sensitive 

species tested; however, the selected toxicity endpoints do not necessarily reflect 

sensitivity of the most sensitive species 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. Toxicity thresholds may

vary up to four orders of magnitude across species for some chemicals11. Therefore, risk 

conclusions may under- or overestimate actual ecological risk for a given species. 

5. Assumptions, Limitations, Uncertainties, Strengths, and 

Data Gaps Related to the Acute and Chronic LOC’s

The risk characterization section of the assessment document includes an evaluation of 

the potential for individual effects to listed species at an exposure level equivalent to the 

LOC. This evaluation is based on the median lethal dose estimate and dose/response 

relationship established for the effects study corresponding to each taxonomic group for 

which the LOCs are exceeded. The slope of the probit-dose response is used to generate 

a probability of individual effects near the low end tail of the curve. Predictions based on 

low probability events are by nature highly uncertain. Moreover, for this assessment the 

dose-response curve representing a given taxa is generated from one study using one 

species. It is likely that the resulting dose-response relationship does not represent the 

response of all species within a taxa. Calculating the probability of individual effects at 

the lower and upper bounds of the slope is designed to address this source of uncertainty

but the extent to which this captures the variability within a taxa is unknown. In some 

cases, a probit dose-response relationship cannot be calculated. In these instances, event 

probabilities are calculated based on a default slope assumption of 4.5 (Urban and Cook, 

1986). 

 

11 Mayer, F.L. and M.R. Ellersieck, 1986. Manual of acute toxicity: Interpretation and data

base for 410 chemicals of freshwater animals. Resource Publication 160. U. S. Fish and 

Wildlife Service. Department of the Interior, Washington, D.C., 579 p.
Page 104 of 114

V. Literature Cited

Open Literature and Other Documents

Arnot, J.A. and F.A.P.C. Gobas. 2004. A food web bioaccumulation model for organic 

chemicals in aquatic ecosystems. Environmental Toxicology and Chemistry, v23 

(10), 2343-2355.

Draft Assessment Report (DAR). 2005. Initial risk assessment provided by the rapporteur 

Member State United Kingdom for the new active substance: Metrafenone as 

referred to in Article 8(1) of Council Directive 91/414/EEC. July 2005.

Fletcher, J.S., J.E. Nellesson, and T. G. Pfleeger. 1994. Literature review and evaluation 

of the EPA food-chain (Kenaga) nomogram, an instrument for estimating 

pesticide residues on plants. Environ. Tox. and Chem. 13(9):1383-1391.

Hoerger, F. and E.E. Kenaga. 1972. Pesticide residues on plants: correlation of 

representative data as a basis for estimation of their magnitude in the 

environment. IN: F. Coulston and F. Corte, eds., Environmental Quality and 

Safety: Chemistry, Toxicology and Technology. Vol 1. George Theime 

Publishers, Stuttgart, Germany. pp. 9-28.

Opalski, K., Tresch, S., Kogel, K-H, Grossmann, K., Kohle, H. and R. Huckelhoven. 

2006. Metrafenone: Studies on the mode of action of a novel cereal powdery 

mildew fungicide. Pest Management Science, 62(5), p.393-401. ISSN 1526-498X.

Urban, D.J. and N.J. Cook, 1986. Hazard Evaluation Division Standard Evaluation 

Procedure Ecological Risk Assessment. EPA 540/9-85-001. U.S. Environmental 

Protection Agency, Office of Pesticide Programs, Washington D.C.

U.S. Environmental Protection Agency (USEPA). 1993. Wildlife Exposure Factors 

Handbook. Office of Research and Development, Washington, D.C. EPA/600/R13/187a.

U.S. Environmental Protection Agency (USEPA) 1998. Guidelines for Ecological Risk 

Assessment. EPA/630/R-95/002F. Published in 63 FR 26846; May 14, 1998. 

U.S. Environmental Protection Agency, Washington, DC. April, 1998.

U.S. Environmental Protection Agency (USEPA). 2004. 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, Pesticides and Toxic Substances, Office of Pesticide 

Programs, Washington, D.C. January 23, 2004. Online at: 

http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf
Page 105 of 114

U.S. Environmental Protection Agency (USEPA). 2006. Pesticide Fact Sheet: 

Metrafenone. New Chemical. September 2006.

U.S. Environmental Protection Agency (USEPA). 2008. (Terrestrial Residue EXposure 

model) Version 1.4.1 (10/09/08). Environmental Fate And Effects Division, 

Office Of Pesticide Programs, U.S. Environmental Protection Agency. 

Willis, G.H., and L.L. McDowell. 1987. Pesticide Persistence on Foliage in Reviews of 

Environmental Contamination and Toxicology. 100: 23-73.

Fate Studies Submitted to the USEPA/Office of Pesticide Programs

MRID 47267450

Zulalian, J. 2001. BAS 560 F (AC 375839): uptake, depuration, bioconcentration and 

metabolism of carbon-14 labeled AC 375839 in bluegill sunfish (Lepomis macrochirus) 

under flow-through conditions: Unpublished study performed by BASF Corporation, 

BASF Agro Research, Princeton, NJ (Analytical Phase) and ABC Laboratories, Inc., 

Aquatic Toxicology Programs Division, Columbia, MO (In-Life Phase; p. 39; Appendix 

B, pp.221-346).

MRID 47267436

Xing, J. 2002. BAS 560 F (CL 375839): laboratory validation of LC/MS determinative 

and LC/MS/MS confirmatory method M 3503 for the determination of BAS 560 F and 

CL 375816 residues in drinking and surface water. Unpublished study performed by

BASF Agro Research, Princeton, New Jersey.

MRID 47267435

Travis, D. 2002. BAS 560 F (CL 375839): laboratory validation of LC/MS 

determinative and LC/MS/MS confirmatory method M 3441 for the determination of 

BAS 560 F and CL 377160 residues in soil. Unpublished study performed by BASF 

Agro Research, Princeton, New Jersey; sponsored and submitted by BASF Corporation, 

Research Triangle Park, North Carolina. 

MRID 47267434

Smalley, R. 2001. Method validation of RLA 12618.00 "LC-MS determination of CL

375839 and CL 377160 residues in soil". Unpublished study performed by BASF Agro 

Research, Gosport, Hampshire, United Kingdom.

MRID 47267431

Panek, M, et al. 2008. Anaerobic aquatic metabolism of 14C-BAS 560 F. Unpublished 

study performed, sponsored and submitted by BASF Corporation, Research Triangle 

Park, North Carolina. 
Page 106 of 114

MRID 47267430

Yan, Z. and R.A. Huang. 2002. BAS 560 F (AC 375839): aerobic transformation in 

water-sediment systems (including Amendment #1). Unpublished study performed by

BASF Corporation, Ewing, New Jersey. 

MRID 47267429

Huang, R. 2002. BAS 560 F: anaerobic soil metabolism. Unpublished study performed, 

sponsored and submitted by BASF Corporation, Research Triangle Park, North Carolina.

MRID 4726728

Afzal, J. 2002. CL 377160 (metabolite of BAS 560 F) rate of degradation in three 

different soils under aerobic conditions. Unpublished study performed by BASF 

Corporation, Princeton, New Jersey.

MRID 47267427

Singh, M. 2008. Aerobic soil metabolism of 14C-BAS 560 F on US soils. Unpublished 

study performed, sponsored and submitted by BASF Corporation, Research Triangle 

Park, North Carolina. 

MRID 47267426

Steinführer, T. 2000. 14C-AC 375839 (CL 375839) Rate of degradation in three different 

soils under aerobic conditions. Unpublished study performed by Cyanamid Forschung 

GmbH, Schwabenheim, Germany.

MRID 47267425

Steinführer, T. 2000. AC 37589: Metabolism in soil under aerobic conditions. 

Unpublished study performed by Cyanamid Forschung GmbH, Schwabenheim, 

Germany. 

MRID 47267424

Ta, C. 2001. BAS 560 F (AC 375839): Soil photolysis. Unpublished study performed by 

BASF Agro Research, Ewing, New Jersey. 

MRID 47267423

Fung, C.H. 2002. BAS 560 F (AC 375839): Aqueous photolysis. Unpublished study

conducted by BASF Agro Research, Princeton and Ewing, New Jersey.

MRID 47267422

An, D. 1999. AC 375839: Hydrolysis. Unpublished study performed by American 

Cyanamid Company, Ewing, New Jersey. 

MRID 47267421

Tornisielo, A. and R. Hoefs. 2008. Adsorption/desorption of a metabolite of BAS 560 F 

(Reg. No. 4082230) on US soils (including Amendment No. 1). Unpublished study
Page 107 of 114

performed by BASF SA, Guaratingueta, Brazil; and sponsored and submitted by BASF 

Corporation, Research Triangle Park, North Carolina. 

MRID 47267421

Tornisielo, A. and R. Hoefs. 2008. Adsorption/desorption of BAS 560 F on US soils 

(including Amendment No. 1). Unpublished study performed by BASF SA, 

Guaratingueta, Brazil; and sponsored and submitted by BASF Corporation, Research 

Triangle Park, North Carolina

MRID 47267432

Jordan,J. J.M. Stewart, and R. Warren. 2008. Terrestrial field dissipation of BAS 560 00F 

in vineyard/orchard and row crop use patterns. Unpublished study performed by Research 

for Hire, Porterville, CA (field phase), Quails Agricultural Laboratory, Inc. Canada (field 

phase), Vaughn Agricultural Research Services, Branchton, Ontario (field phase), 

Research Options, Inc., Winter Garden, Florida (field phase), BASF RTP, NC (analytical 

phase); and Agvise Laboratories, Inc. Northwood ND.

Effects Studies Submitted to the USEPA/Office of Pesticide Programs

MRID 47267502

Ahmed, M.S., R. Troup and T. Harris. 2000(a). Avian acute oral toxicity test with AC 

375839 Technical in Northern Bobwhite (Colinus virginianus). BASF Doc ID 

2000/7000117.

MRID 47267503

Ahmed, M.S., R. Troup and T. Harris. 2000(b). Avian acute oral toxicity test with AC 

375839 Technical in Mallard Duck (Anas platyrhynchos). BASF Doc ID 2000/7000115.

MRID 47267504

Ahmed, M.S., R. Troup and T. Harris. 2000(c). Avian dietary toxicity test with AC 

375839 Technical in Northern Bobwhite (Colinus virginianus). BASF Doc ID 

2000/7000126.

MRID 47267505

Ahmed, M.S., R. Troup and T. Harris. 2000(d). Avian dietary toxicity test with AC 

375839 Technical in Mallard Duck (Anas platyrhynchos). BASF Doc ID 2000/7000125.

MRID 47267506

Ahmed, M.S. and M. Rodgers. 2002. BASF: Assessment to determine the effects on 

reproduction in Northern Bobwhite (Colinus virginianus). BASF Doc ID 2002/7005090.

MRID 47267515

Barker, C., K.Drottar and H. Krueger. 2000(a). Effect of AC 375839 on growth of the 

green alga, Selenastrum capricornutum. BASF Doc ID 2000/7000122.
Page 108 of 114

MRID 47267449

Barker, C., K.Drottar and H. Krueger. 2000(b). Toxicity of AC 375839 during the early 

life-stages of the Fathead Minnow (Pimephales promelas). BASF Doc ID 2000/7000128.

MRID 47267447

Barker, C., K.Drottar and H. Krueger. 2000(c). Toxicity of AC 375839 during the lifecycle of the Cladoceran (Daphnia magna). BASF Doc ID 2000/7000130.

MRID 47267448

Cafarella, M. 2007. BAS 560 F – Life-cycle toxicity test with mysids (Americamysis 

bahia). BASF Doc ID 2007/7009454.

MRID 47267512

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(a). A 96-hour toxicity test 

with the freshwater alga (Anabaena flos-aquae). BASF Doc ID 2005/7003441.

MRID 47267514

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(b). A 96-hour toxicity test 

with the freshwater diatom (Navicula pelliculosa). BASF Doc ID 2005/7003436.

MRID 47267513

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(c). A 96-hour toxicity test 

with the marine diatom (Skeletonema costatum). BASF Doc ID 2005/7003443.

MRID 47267511

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(d). A 7-day static renewal 

toxicity test with duckweed (Lemna gibba G3). BASF Doc ID 2005/7003440.

MRID 47267438

Jatzek, J. 2002(a). CL 375816 (Metabolite of BAS 560 F, Benzophenone) –

Determination of the acute effect on the swimming ability of the water flea Daphnia 

magna STRAUS. BASF Doc ID 2002/1004870. 

MRID 47267516

Jatzek, J. 2002(b). CL 375816 (Metabolite of BAS 560 F, Benzophenone) –

Determination of the inhibitory effect on the cell multiplication of unicellular green 

algae. BASF Doc ID 2002/1004873.

MRID 47267439

Jatzek, J. 2002(c). CL 4084564 (Metabolite of BAS 560 F, Benzophenone) –

Determination of the acute effect on the swimming ability of the water flea Daphnia 

magna STRAUS. BASF Doc ID 2002/1004869.

MRID 47267517

Jatzek, J. 2002(d). CL 4084564 (Metabolite of BAS 560 F, Benzophenone) –

Determination of the inhibitory effect on the cell multiplication of unicellular green 

algae. BASF Doc ID 2002/1004872.
Page 109 of 114

MRID 47267501

Krueger, H., MacGregor, J., Jaber, M. and C. Barker. 2001. Toxicity of BAS 560 F to 

Chironomus riparius during a prolonged sediment toxicity test. BASF Doc ID 

2001/7000462. 

MRID 47267519

Luhrs, U. 2001. Acute toxicity (14 days) of Metabolite CL 377160 (Metabolite of BAS 

560 F, Benzophenone) to the earthworm Eisenia fetida in artificial soil. BASF Doc ID 

2001/ 1007447.

MRID 47267518

Mulligan, E. 2001(a). Acute toxicity of AC 375839 to the earthworm Eisenia fetida. 

BASF Doc ID 2001/7000259.

MRID 47267608

Mulligan, E. 2001(b). Acute toxicity of AC 375839 300 g/L SC RLF 12359 (SF 10358) 

to the earthworm Eisenia fetida. BASF Doc ID 2001/7000262.

MRID 47267442

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(a). Acute toxicity of AC 

375839 to bluegill, Lepomis macrochirus, under flow-through test conditions. BASF Doc 

ID 1999/7000286.

MRID 47267443

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(b). Acute toxicity of AC 

375839 to rainbow trout, Oncorhynchus mykiss, under flow-through test conditions. 

BASF Doc ID 1999/7000289.

MRID 47267437

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(c). Acute toxicity of AC 

375839 to Daphnia magna under static test conditions. BASF Doc ID 1999/7000287.

MRID 47267605

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(a). Acute toxicity of BAS 560 

00F (SF 10358, RLF 12359) to rainbow trout (Oncorhynchus mykiss) under static test 

conditions. BASF Doc ID 2001/7000463.

MRID 47267604

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(b). Acute toxicity of BAS 560 

00F (SF 10358, RLF 12359) to Daphnia magna under static test conditions. BASF Doc 

ID 2001/7000464.
Page 110 of 114

MRID 47267607

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(c). Acute toxicity of BAS 560 

00F (SF 10358, RLF 12359) on growth of the green alga, Selenastrum capricornutum. 

BASF Doc ID 2001/7000465.

MRID 47267441

Palmer, S., T. Kendall, H. Krueger and A. Van Cott, 2005(a). A 96-hour flow-through 

acute toxicity test with the saltwater mysid (Americamysis bahia). BASF Doc ID 

2005/7003438.

MRID 47267446

Palmer, S., T. Kendall, H. Krueger and A. Van Cott, 2005(b). A 96-hour flow-through 

acute toxicity test with the sheepshead minnow (Cyprinodon variegatus). BASF Doc ID 

2005/7003439.

MRID 47267440

Palmer, S., T. Kendall, H. Krueger and A. Van Cott, 2005(c). A 96-hour shell deposition 

test with the eastern oyster (Crassostrea virginica). BASF Doc ID 2005/7003442.

MRID 47267510

Porch, J. and H. Krueger. 2001. Effect of BAS 560 F 500g/L SC (RLF 12380) on 

vegetative vigor of ten species of plants. BASF Doc ID 2001/7002392.

MRID 47267509

Porch, J., K. Martin, and H. Krueger. 2001. Effect of BAS 560 F 500 g/L SC (RLF 

12380) on seedling emergence of ten species of plants. BASF Doc ID 2001/7002391.

MRID 47267508

Strnad, A. and E. Mulligan. 2002(a). Acute toxicity of AC 375839 Technical to the 

honeybee, Apis mellifera. BASF Doc ID 2002/7004414.

MRID 47267606

Strnad, A. and E. Mulligan. 2002(b). Acute toxicity of AC 375839 in a 300 g/L SC (SF 

10358/RLF 12359) to the honeybee, Apis mellifera. BASF Doc ID 2002/7004415.

MRID 47267444

Zok, S. 2002(a). Reg. No. 4074484 (Metabolite of BAS 560 F) – Acute toxicity study on 

the rainbow trout (Oncorhynchus mykiss) in a static system over 96 hours. BASF Doc ID 

2002/1004394.

MRID 47267445

Zok, S. 2002(b). CL 4084564 (Metabolite of BAS 560 F) – Acute toxicity study on the 

rainbow trout (Oncorhynchus mykiss) in a static system over 96 hours. BASF Doc ID 

2002/1005255.
Page 111 of 114

MRID 47267507

Zok, S. 2006. BAS 560 F – 1 Generation reproduction study on the mallard duck (Anas 

platyrhynchos) by administration in the diet. BASF Doc ID 2006/1018046.
Page 112 of 114

VI. Appendices

Appendix A. Chemical Names, Structures, and Maximum Reported Amounts of Metrafenone and 

Its Degradates.

Appendix B. Aquatic Model Input/Output Data.

Appendix C. Example T-REX Output for Metrafenone.

Appendix D. Example KABAM (v. 1.0) Results for Metrafenone.

Appendix E. LOCATES Output of Listed Species.

Appendix F. Submitted Environmental Fate Studies for Metrafenone.

Appendix G. Submitted Ecological Effects Studies for Metrafenone.

Appendix H. The Risk Quotient Method.

VII. List of Figures

Figure 1. Chemical Structure of Metrafenone...................................................13

Figure 2. Conceptual Model Depicting Sources of Exposure from Metrafenone as well as 

Metrafenone Residues, Potential Receptors, and Adverse Effects from the Proposed Uses 

of Metrafenone on Grapes.........................................................................19

VIII.List of Tables

Table 1. Summary of Environmental Risk Conclusions for Aquatic Animals and Plants 

from Metrafenone Use on Grapes at the Maximum Proposed Application Rate.............6

Table 2. Summary of Environmental Risk Conclusions for Terrestrial Animals and Plants 

from Metrafenone Use on Grapes at the Maximum Proposed Application Rate.............6

Table 3. Listed Species Risks Associated with Direct or Indirect Effects from 

Metrafenone use on Grapes at the Maximum Proposed Application Rate...................12

Table 4. Environmental Fate Properties of Metrafenone.......................................14

Table 5. Metrafenone Use and Application Information Based on the Proposed Label for 

Metrafenone 300 SC................................................................................15
Page 113 of 114

Table 6. Test Species Evaluated for Assessing Potential Ecological Effects of 

Metrafenone and the Associated Acute Toxicity Classification...............................16

Table 7. Measures of Ecological Effects and Exposure for Metrafenone...................26

Table 8. Total Extractable Metrafenone Residue Half-lives from Laboratory Degradation 

Studies................................................................................................32

Table 9. Scenarios used to Estimate Metrafenone Concentrations in Surface Water.......33

Table 10. PRZM/EXAMS Input Parameteres for Metrafenone and Total Extractable 

Metrafenone Residues...............................................................................33

Table 11. Estimated Exposure Concentrations for Metrafenone and Total Metrafenone 

Residues from Surface Water......................................................................34

Table 12. Input Parameters and Chemical Characteristics of Metrafenone Used in 

KABAM..............................................................................................35

Table 13. Estimated Concentrations of Metrafenone in Fish (based on metrafenone total 

residue scenario).....................................................................................35

Table 14. Terrestrial Food-Item Residue Estimates for Birds with Metrafenone Proposed 

Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14 day app. interval) with a Foliar 

Dissipation Half-life default value of 35 Days .................................................37

Table 15. Terrestrial Food-Item Residue Estimates for Mammals with Metrafenone 

Proposed Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14 day app. interval) with a Foliar 

Dissipation Half-life default value of 35 Days .................................................37

Table 16. Estimated Environmental Concentrations of Metrafenone for Terrestrial Plants 

from Grape Use......................................................................................38

Table 17. Freshwater Fish Acute Toxicity Data.............................................. 39

Table 18. Freshwater Invertebrate Acute Toxicity Data.......................................43

Table 19. Marine/Estuarine Fish Acute Toxicity Data.........................................45

Table 20. Marine/Estuarine Invertebrate Acute Toxicity Data................................46

Table 21. Freshwater Fish Chronic Toxicity Data..............................................47

Table 22. Marine/Estuarine Invertebrate Chronic Toxicity Data.............................49

Table 23. Aquatic Plant Toxicity Data...........................................................51
Page 114 of 114

Table 24. Avian Acute Toxicity Data............................................................55

Table 25. Mammalian Acute Toxicity Data.....................................................57

Table 26. Terrestrial Invertebrate Acute/Subacute Toxicity Data............................60

Table. 27. Avian Chronic Toxicity Data.........................................................63

Table. 28. Mammalian Chronic Toxicity Data..................................................65

Table 29. Metrafenone: Chronic Risks to Marine/Estuarine Invertebrates (Application 

Rate 0.3 lbs a.i./L, 6 Applications/Year).........................................................70

Table 30. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients...........72

Table 31. Chronic RQ Values for Birds Consuming Fish Contaminated by Metrafenone 

(based on KABAM).................................................................................73

Table 32. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients....73

Table 33. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients......74

Table 34. Chronic RQ Values for Mammals Consuming Fish Contaminated by

Metrafenone (based on KABAM)................................................................74

Table 35. Listed Species Risks Associated with Direct or Indirect Effects from 

Metrafenone use on Grapes at the Maximum Proposed Application Rate...................88

Table 36. Number of Endangered Species Potentially Exposed to Metrafenone as used on 

grapes..................................................................................................94

Table 37. Number of Endangered Species Potentially Exposed to Metrafenone as used on 

grapes.................................................................................................94