Fenamidone Summary of Analytical Chemistry and Residue Data Barcode D410422

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND

POLLUTION PREVENTION

MEMORANDUM

Date: 12/18/13

Subject: Fenamidone. Residue Chemistry Summary Document to Support New Uses and 

Tolerances on Ginseng, Succulent Beans (Except Cowpea), Bulb Onion (Subgroup 3-

07A), and Green Onion (Subgroup 3-07B). Summary of Analytical Chemistry and 

Residue Data.

PC Code: 046679 DP Barcode: D410422

Decision No.: 475185 Registration No.: 264-693

Petition No.: 3E8150 Regulatory Action: Section 3 Registration

Risk Assessment Type: NA Case No.: NA

TXR No.: NA CAS No.: 161326-34-7

MRID No.: See Below 40 CFR: 180.579

From: Karen Milians, Ph.D., Chemist

Ideliz Negrón-Encarnación, Ph.D., Chemist

Risk Assessment Branch VII

Health Effects Division (7509P)

Through: William Donovan, Ph.D., Senior Chemist

 Michael Metzger, Branch Chief

Risk Assessment Branch VII

Health Effects Division (7509P)

To: Laura Nollen, Risk Manager Reviewer

Barbara Madden, Risk Manager

Registration Division (7505P)

Summary of Submitted Residue Chemistry Studies

OCSPP 860 

Series Guideline

MRID Number Title

860.1500 49052101 Fenamidone: Magnitude of the Residue on Ginseng

860.1500 49052102 Fenamidone: Magnitude of the Residue on Bean (Lima)

860.1500 49052103 Fenamidone: Magnitude of the Residue on Bean (Snap)
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Table of Contents

1.0 Executive Summary............................................................................................................ 3

2.0 Regulatory Recommendations......................................................................................... 4

2.1 Data Deficiencies/Data Needs.......................................................................................... 4

2.2.1 Enforcement Analytical Method............................................................................... 4

2.2.2 Recommended Tolerances........................................................................................ 4

2.2.3 Revisions to Petitioned-For Tolerances.................................................................... 5

2.2.4 International Harmonization ..................................................................................... 5

3.0 Introduction......................................................................................................................... 6

3.1 Chemical Identity ............................................................................................................. 6

3.2 Physical/Chemical Characteristics................................................................................... 6

3.3 Pesticide Use Pattern/Directions for Use (860.1200)....................................................... 7

4.0 Metabolite/Degradate Residue Profile.......................................................................... 8

4.1 Nature of the Residue ................................................................................................... 8

4.1.1 Summary of Plant/Livestock Metabolism (860.1300).............................................. 8

4.1.2 Summary of Confined Rotational Crops (860.l850)................................................. 8

4.2 Residues of Concern Summary and Rationale................................................................. 8

5.0 Residue Profile.................................................................................................................... 9

5.1 Residue Analytical Methods (860.1340).......................................................................... 9

5.1.1 Data Collection Methods .......................................................................................... 9

5.1.2 Multi-Residue Methods (860.1360)........................................................................ 10

5.1.3 Tolerance Enforcement Methods............................................................................ 11

5.1.4 Submittal of Analytical Reference Standards (860.1650) ...................................... 11

5.2 Storage Stability (860.1380) .......................................................................................... 11

5.3 Residue Data .................................................................................................................. 13

5.3.1 Crop Field Trials (860.1500) .................................................................................. 13

5.3.2 Field Rotational Crops (860.1900) ......................................................................... 17

5.3.3 Processed Food and Feed (860.1520)..................................................................... 17

5.3.4 Meat, Milk, Poultry and Eggs (860.1480) .............................................................. 17

6.0 Tolerance Derivation ........................................................................................................ 19

Appendix A. Field Trial Geographic Distribution....................................................................... 20

Appendix B. International Residue Limits Table ........................................................................ 21

Appendix C. OECD MRL Calculation Procedure Inputs/Outputs.............................................. 22
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1.0 Executive Summary

Fenamidone is foliar fungicide currently registered for application to a variety of field crops 

including, bulb vegetables, root vegetables, tuberous and corm vegetables, fruiting vegetables 

and leafy vegetables. In addition, fenamidone is registered for non-food uses such as cotton and 

tobacco. Fenamidone is a chiral compound with the technical product consisting of 98.5% Sfenamidone. 

Residue field trial studies were submitted by the IR-4 Project on behalf of Bayer Crop Science, 

to support the registration request for the use of fenamidone (formulated as Reason®500 SC) on 

ginseng, and succulent beans. The data in the studies are classified as scientifically acceptable 

with the exemption of the residue data for metabolite RPA 405862, because frozen storage 

stability was not demonstrated. Additionally, adequate analytical methods are available to 

enforce the proposed tolerances including the FDA multi-residue method protocol D. An 

adequate number of field trials with appropriate geographic representation have been provided to 

allow HED to establish tolerances on ginseng, and succulent beans (except cowpea). In addition, 

the registrant proposed tolerances for bulb onion (subgroup 3-07A), and green onion (subgroup 

3-07B). Adequate data is available to establish tolerances on these subgroups based on residue 

data for bulb onions and green onions. 

Ginseng is typically harvested after 3-4 years growth; therefore, in order to simulate the effects 

of multi-year applications, the registrant carried out field trials using a 3x exaggerated 

application rate of fenamidone (2.48 lbs a.i./A) than that stated on the label (maximum yearly 

0.80 lbs a.i./A). Based on this, five field trials were performed with ginseng by applying Reason®

500 SC at total rates of 2.43-2.48 lbs a.i./A and one field trial with a total of 0.817 lbs a.i./A. 

Fenamidone residues in dried ginseng roots treated with 9 foliar broadcast applications of 

fenamidone at total rates of 2.43-2.48 lbs a.i./A ranged from 0.02-0.53 ppm, when samples were 

harvested at 12-15 day PHIs whereas, residues of metabolites RPA 408056 (DA-Fen), and RPA 

405862 ranged from <0.02-0.028, and from <0.02-0.024 ppm, respectively, while for RPA 

717879 (DADK-Fen) were all <0.02 ppm. Additionally, fenamidone residues in dried ginseng 

roots treated with foliar broadcast applications of fenamidone at total rates of 0.817 lbs a.i./A and 

harvested at 14-day PHI ranged from 0.049-0.059 ppm, and residues of the metabolites RPA 

717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were all <0.02 ppm. Tolerance 

for ginseng was calculated using the highest application rate for the field trials (2.48 lbs a.i./A). 

Residue decline behavior was not assessed.

Eight field trials were performed with snap beans by applying Reason®500 SC to snap beans in 

4 foliar broadcast or foliar directed applications at rates of 0.259-0.278 lbs a.i./A, RTIs of 6-8 

days, for total application rates of 1.05-1.36 lbs a.i./A/season. Commercially mature snap bean 

pods with seeds, and plants with pods were harvested at all trial sites at 3-4 day PHIs. 

Fenamidone residues in snap bean pods with seeds ranged from 0.084-0.46 ppm. Residues of the 

metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were all <0.02 

ppm. Fenamidone residues decreased with increasing PHI when snap bean pods with seeds were 

harvested at PHIs of 1, 3, 7, and 13 days. Residues of the metabolites RPA 717879 (DADKFen), RPA 408056 (DA-Fen), and RPA 405862 were all <0.02 ppm in snap bean pods with seeds 
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at all PHIs. Residues in snap bean plants with pods ranged from 1.3-15.9 ppm. Residues of the 

metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 ranged from 

<0.02-0.042, 0.046-0.17, and <0.02-0.094 ppm, respectively. Residue decline behavior was 

determined at PHI of 1, 7 and 13 days and demonstrated that residues decreased with increasing 

PHI.

Nine field trials were performed with succulent lima beans by applying Reason®500 SC as 4 

foliar broadcast at 0.259-0.278 lbs a.i./A, RTIs of 6-9 days, for total application rates of 1.05-

1.10 lbs a.i./A. Residues in succulent lima bean seeds without pods ranged from <0.02-0.08 ppm 

when samples were harvested at 2-4 day PHIs. Similarly, residues of the metabolites RPA 

717879 (DADK-Fen), RPA 408056 (DA-Fen) RPA 405862 were all <0.02 ppm. 

2.0 Regulatory Recommendations

There are no residue chemistry deficiencies that would preclude the establishment of tolerances

for residues of fenamidone on the commodities below. 

Ginseng ............................................................................................... 0.80 ppm

Bean, succulent, except cowpea... ................................................................ 0.80 ppm

Onion, bulb, subgroup 3-07A ..................................................................... 0.20 ppm

Onion, green, subgroup 3-07B..................................................................... 1.5 ppm

2.1 Data Deficiencies/Data Needs

None.

2.2.1 Enforcement Analytical Method

The current tolerance enforcement method entitled RPA 407213: method of Analysis for RPA 

407213 and its Metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen) and RPA 405862

(MRID No. 45385918), a liquid chromatographic method coupled with tandem mass spectrum 

detection (LC/MS/MS) has been radiovalidated. Further the method has undergone successful 

ILV (independent laboratory validation) as well as validation by the Agency on a number of 

commodities including potato, cucumber, cantaloupe, lettuce, onion, tomato (fruit, paste, and 

puree), spinach, and wheat (forage, hay, straw, grain, bran, flour, shorts, germ, and middlings). 

Conclusion: The data acquisition method is similar to the enforcement method. Therefore, HED 

concludes that the enforcement method is also suitable to enforce the new plant tolerances 

proposed in this petition. 

2.2.2 Recommended Tolerances

HED recommends that 40 CFR be amended by establishing tolerances for the plant commodities 
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listed in the Table 1. Tolerances for residues on ginseng, succulent beans, bulb onion (subgroup 

3-07A), and green onion (subgroup 3-07B) have been submitted to support the proposed uses of 

fenamidone. The tolerances for plant commodities should be defined as follows:

 

Tolerances are established for residues of fenamidone including its metabolites and degradates, 

or on the commodities in the table below. Compliance with the tolerance levels for fenamidone 

is to be determined by measuring only fenamidone ((S)-l-anilino-4-methyl-2-methylthio-4-

phenylimidazolin-5-one).

Table 1. Tolerance Summary for Fenamidone.

Commodity Established*/Proposed 

Tolerance (ppm)

HED-Recommended 

Tolerance (ppm)

Comments 

(correct commodity definition)

Ginseng 0.8 0.80

Bean, succulent 0.8 0.80 Bean, succulent, except cowpea

Onion, bulb, subgroup 

3-07A 

0.2 0.20

Onion, green, subgroup 

3-07B

1.5 1.5

Garlic 0.20* Remove These commodities are covered 

under the proposed / 

recommended onion, bulb, 

subgroup 3-07A and onion, 

green, subgroup 3-07B.

Garlic, great headed 0.20* Remove

Onion, dry bulb 0.20* / Remove Remove

Onion, green 1.5* / Remove Remove

Onion, welsh 1.5* Remove

Shallot, bulb 0.20* Remove

Shallot, fresh leaves 1.5* Remove

* Established tolerances under the 40 CFR 180.579.

2.2.3 Revisions to Petitioned-For Tolerances

The succulent bean definition includes cowpea which has forage and hay commodities that are 

considered significant livestock feedstuffs. The dietary burden associated with uses on cowpea is 

not supported by an appropriate feeding study; therefore, uses on cowpea have to be excluded 

from succulent bean. In addition, tolerances established in the 40 CFR 180.579 (see Table 1) for 

commodities covered under subgroups 3-07A and 3-07B should be removed. The registrant 

should submit a revised Section F in which the proposed tolerances are the same as those 

recommended by HED.

2.2.4 International Harmonization

Mexican and Codex MRLs have not been established for the commodities under consideration. 

The recommended tolerance definition and levels for onion, bulb, subgroup 3-07A, and onion, 

green, subgroup 3-07B are harmonized with established Canadian Maximum Residue Limits 

(MRLs) for similar commodities. Moreover, identical regulatory levels are being recommended 

by EPA and PMRA reviewers for ginseng and commodities under the succulent bean definition 

as part of this joint review.
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2.3 Label Recommendations

No recommendations are provided for the proposed new uses on ginseng, succulent beans, onion, 

bulb, subgroup 3-07A and onion, green, subgroup 3-07B.

3.0 Introduction

Fenamidone is a broad-spectrum foliar fungicide currently registered for application to a variety 

of field crops including bulb vegetables, tuberous and bulb vegetables, cucurbit vegetables, 

fruiting vegetables, leafy vegetables, potatoes, and root vegetables. Fenamidone is a chiral 

compound with the technical product consisting of 98.5% S-fenamidone (REASON®500 SC). 

Tolerances are established for residues of fenamidone in raw agricultural commodities, animal 

commodities and for inadvertent residues under 40 CFR 180.579.

3.1 Chemical Identity

Table 2. below shows fenamidone nomenclature.

Table 2. Fenamidone Nomenclature.

Fenamidone, RPA 407213 Chemical Structure

Common name Fenamidone

Company experimental name RPA 407213

IUPAC name (S)-l-anilino-4-methyl-2-methylthio-4-phenylimidazolin-5-one

CAS name (5S)-3,5-dihydro-5-methyl-2-(methylthio)-5-phenyl-3-(phenylamino)-4Himidazol-4-one

CAS # 161326-34-7

End-use product/EP REASON®500 SC fungicide, PCP# 27462

3.2 Physical/Chemical Characteristics

Fenamidone is moderately soluble in water (FAO, 2000)

1

and not likely to volatize due to low 

vapor pressure. Based on the octanol/water partition coefficient (Kow) fenamidone partitions to 

the lipophilic phase. However, it is soluble in both polar and non-polar solvents. Refer to Table 

3. below for the physicochemical properties of fenamidone.

 

1

FAO, 2000. Food and Agriculture Organization of the United Nations. FAO Pesticide Disposal Series 8. Assessing Soil 

Contamination: A Reference Manual. Appendix 2. Parameters of pesticides that influence processes in the soil. Editorial Group, 

FAO Information Division: Rome, 2000. http://www.fao.org/docrep/003/X2570E/X2570E00.htm. 

N

N

CH3

O S

CH3

N

H
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Table 3. Physicochemical Properties of the Technical Grade Fenamidone

Parameter Value Reference (MRID)

Formula/Molecular weight (g/mole) C17H17N3OS - 311.401 NA

Melting point/range (°C) 135.5 45385708

pH 5.7 45385714

Density (g/cm3) 1.288 45385708

Water solubility ( mg/L at 20°C) 7.8 45385712

Solvent solubility (mg/L at RT) 330,000 methylene chloride

250,000 acetone

106,000 ethyl acetate

86,000 acetonitrile

43,000 methanol

40,000 toluene

300 heptane

45385712

Vapor pressure at 20°C (Pa) 2.60X10-9 MRID 45385711

Dissociation constant (pKa) No measurable dissociation 

constants in the pH range of 1 to 13

MRID 45385714

Octanol/water partition coefficient Log(KOW) 631 (2.8) MRID 45385713

3.3 Pesticide Use Pattern/Directions for Use (860.1200)

Fenamidone can be applied by ground, aerial or chemigation on ginseng, succulent beans and 

bulb vegetables. The maximum seasonal application for these crops is 0.80 lbs a.i./A and the 

application rate is 0.178-0.267 lbs a.i./A (Refer to Table 4). The pre-harvest interval (PHI) is 14 

days for ginseng and 3 days for lima and snap beans. However, the maximum number of 

applications per season is not specified for these crops on the label. 

Table 4. Summary of Proposed Directions for Use of Fenamidone.

Applic. 

Timing, Type, 

and Equip.

Formulation

[EPA Reg. 

No.]

Applic. Rate 

(lb a.i./A)

Max. No. 

Applic. per 

Season

Max. Seasonal 

Applic. Rate

(lb a.i./A)

PHI

(days)

Use Directions and 

Limitations

Ginseng

Reason®500 

SC fungicide,

ground, aerial, 

chemigation

264-695 0.178-0.267 Not 

Specified 0.80 14 14 day RTI

Succulent Beans

Reason®500 

SC fungicide, 

ground, aerial, 

chemigation

264-695 0.178-0.267 Not 

Specified 0.80 3 7 day RTI

Bulb Vegetables

Reason®500 

SC fungicide, 

ground, aerial, 

chemigation

264-695 0.178 Not 

Specified 0.71 7 5-10 days RTI

Conclusions: The proposed use directions are sufficient to allow evaluation of the crop field 

trial studies. The proposed use pattern is supported by the crop field trial data in succulent beans 

(lima beans and snap beans) and bulb vegetables. The use pattern applied in the ginseng crop 
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field trials was selected to reflect multi-year applications; therefore, it differs to the yearly use 

pattern described in the label. This is considered adequate for ginseng, see further discussion in 

the crop field trial section.

4.0 Metabolite/Degradate Residue Profile

4.1 Nature of the Residue

4.1.1 Summary of Plant/Livestock Metabolism (860.1300)

D314318, 6/14/2007, T. Bloem

No new metabolism studies were submitted for this petition. Based on data submitted on the 

metabolism of fenamidone on potatoes, tomatoes, lettuce, grapes and carrots, HED concludes 

that the nature of the residue in plants has been adequately delineated to support this request for 

crop use on ginseng, succulent beans and bulb onion (subgroup 3-07A), and green onion 

(subgroup 3-07B). The HED Metabolism Assessment Review Committee (MARC) has 

reviewed metabolism studies, rotational crop studies and environmental fate data (MARC 

memos- T. Bloem et al., 11-July-2002; T. Bloem et al., 25-May-2004). 

The residue of concern (ROC) for tolerance enforcement in plants is parent fenamidone. The 

ROC for risk assessment in all plant commodities except carrot is parent fenamidone and the 

metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862. HED 

reconsidered the ROC definition for root vegetables. In order to account for the major 

metabolites observed in the carrot and potato metabolism studies HED recommends that for 

future field trial data with root vegetables parent fenamidone, RPA 413255, RPA 717879 

(DADK-Fen) and RPA 408056 (DA-Fen), RPA 405862 are measured and that the residues of 

concern for risk assessment are considered on a case by case basis. For ginseng, based on the 

lack of information pertaining to the absence/presence of RPA 413255 in the crop field trials, a 

metabolite ratio 0.6X will be used for dietary assessment purposes. This ratio is based on the 

carrot metabolism study (D314318, T. Bloem, 06/07/2007). The residues of concern for 

tolerance setting and risk assessment purposes are summarized in Table 5.

4.1.2 Summary of Confined Rotational Crops (860.l850)

D314318, T. Bloem, 6/14/2007

Confined rotational crop data on lettuce, turnip and barley were previously submitted to the 

Agency. The Agency has determined that the residue of concern in rotational crops for purposes 

of tolerance setting is fenamidone and its metabolite, RPA 717879 (DADK-Fen). The residue of 

concern in rotational crops for purposes of risk assessment is fenamidone, and its metabolites 

RPA 717879 (DADK-Fen), and RPA 408056 (DA-Fen) (free and conjugated). 

4.2 Residues of Concern Summary and Rationale

MARC memos- T. Bloem et al, 2002; T. Bloem et al., 25-May-2004.

The residues of concern for tolerance setting and risk assessment purposes are summarized in 

Table 5.
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Table 5. Summary of Metabolites and Degradates to be included in the Risk Assessment 

and Tolerance Expression

Matrix Residues included in 

Tolerance Expression

Residues included in Risk 

Assessment 

Plants

Primary Crop

(excluding carrot)

Fenamidone 

Fenamidone, RPA 717879 

(DADK-Fen), RPA 408056 

(DA-Fen), and RPA 405862

Carrot1Fenamidone Fenamidone, and RPA 

413255

Rotational Crop Fenamidone, RPA 717879

(DADK-Fen)

Fenamidone, RPA 717879

(DADK-Fen) and RPA 

408056 (DA-Fen) (free and 

conjugated)

Livestock

Ruminant

Fenamidone, RPA 717879 

(DADK-Fen)

Fenamidone, RPA 717879 

(DADK-Fen) and RPA 

408056 (DA-Fen) (free and 

conjugated) Poultry

Drinking Water Not Applicable

1

For future field trials with the root vegetables, HED recommends that parent fenamidone, and the metabolites RPA

413255, RPA 717879 (DADK-Fen) and RPA 408056 (DA-Fen), and RPA 405862 are measured.

5.0 Residue Profile

5.1 Residue Analytical Methods (860.1340)

5.1.1 Data Collection Methods

49052101, 49052102, 49052103, Fenamidone: Magnitude of the Residue on ginseng, Lima and Snap Bean, 

respectively.

Residues of fenamidone and the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), 

and RPA 405862 were determined using the analytical method entitled “RPA 407213: Method of 

Analysis for RPA 407213 and its Metabolites RPA 717879 (DADK-Fen), RPA 408056 (DAFen), and RPA 405862 in Plants”. This method has been assessed previously and is acceptable 

for data gathering purposes. The reference method was modified slightly for the current study by

not filtering extracts after the initial extractions, and by omitting the use of clean-up cartridges as 

they were not required. However, this did not appear to affect the analyses as the chromatograms 

of the samples matched those of the controls. Briefly, residues were extracted twice with 

acetonitrile:water (80:20; v/v), the extracts were combined, and then diluted at least 10 times 

with methanol:water (10:90; v/v). Residues were then determined by liquid 

chromatography/mass spectroscopy/mass spectroscopy (LC/MS/MS). The LLMV for all 

analytes in all matrices was 0.02 ppm.

The calculated LOQ was determined to be 0.03, 0.008, 0.009, and 0.012 ppm for residues of 

fenamidone, and metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 
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405862 in dried ginseng roots, respectively. The calculated LOD was determined to be 0.009, 

0.003, 0.003, and 0.004 ppm for residues of fenamidone, and metabolites RPA 717879 (DADKFen), RPA 408056 (DA-Fen), and RPA 405862 in dried ginseng roots, respectively. The LLMV 

was 0.02 ppm for all analytes in dried ginseng roots. 

Similarly, the LOQ was determined to be 0.00972, 0.01102, 0.00557, and 0.01065 ppm for 

residues of fenamidone, and metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), 

and RPA 405862 in succulent lima bean seeds without pods, respectively. The calculated LOD 

was determined to be 0.00324, 0.00367, 0.00186, and 0.00355 ppm for residues of fenamidone, 

and metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 in 

succulent lima bean seeds without pods, respectively. The LLMV was 0.02 ppm for all analytes 

in succulent lima bean seeds without pods. The method was validated prior to sample analysis by 

spiking control lima bean seeds without pods with 0.02, 0.2, and 2.0 ppm fenamidone, and its 3 

metabolites. Adequacy of the method was also confirmed by spiking control samples with 0.02 

and 0.2 ppm of each analyte, and determining recoveries concurrently with analysis of treated 

sample sets. 

Finally, for snap beans in pods with seeds, the LOQ was calculated to be 0.020, 0.019, 0.006, 

and 0.005 ppm for residues of fenamidone, and metabolites RPA 717879 (DADK-Fen), RPA 

408056 (DA-Fen), RPA 405862, respectively. The LOD was calculated to be 0.007, 0.006, 

0.002, and 0.002 ppm for residues of fenamidone, and metabolites RPA 717879 (DADK-Fen), 

RPA 408056 (DA-Fen), RPA 405862, respectively. On the contrary, snap bean plants with pods, 

the LOQ was calculated to be 0.033, 0.025, 0.013, and 0.012 ppm for residues of fenamidone, 

and metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), RPA 405862, respectively. 

Also, in snap bean plants with pods, the LOD was calculated to be 0.011, 0.008, 0.004, and 0.004 

ppm for residues of fenamidone, and metabolites RPA 717879 (DADK-Fen), RPA 408056 (DAFen), RPA 405862, respectively. 

Conclusions: All method validation and concurrent recoveries were within the acceptable 70-

120% range. Therefore, the reference method, is adequate for the determination of fenamidone, 

and the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 in 

ginseng roots and succulent beans in the studies.

5.1.2 Multi-Residue Methods (860.1360)

D314318, T. Bloem, 6/14/2007

Fenamidone, RPA 408056 (DA-Fen), RPA 717879 (DADK-Fen), and RPA 405862 were tested 

through FDA multi-residue methods. Residues of fenamidone and all three metabolites were 

completely recovered from fortified lettuce during Protocol D. Low recoveries of fenamidone 

were observed from Protocols E (31%) and F (54%). Metabolites RPA 408056 (DA-Fen), RPA 

717879 (DADK-Fen), and RPA 405862 were not recovered using Protocols E and F. Protocol B 

was not tested because fenamidone and its metabolites are not acids or phenols, and Protocol A 

was not fully tested because the compounds were not found to naturally fluoresce. 

Conclusions: The multi-residue method (Protocol D) is adequate for determining residues for 

dietary exposure assessment and has the potential to be the primary enforcement method. 
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5.1.3 Tolerance Enforcement Methods

D357372, 2/24/09, A. LaMay

The current tolerance enforcement method entitled RPA407213: method of Analysis for RPA 

407213 and its Metabolites RPA 717879, RPA 408056 and RPA 405862 (MRID No. 45385918), 

a liquid chromatographic method coupled with tandem mass spectrum detection (LC/MS/MS) 

has been radiovalidated. Further the method has undergone successful ILV (independent 

laboratory validation) as well as validation by the Agency on a number of commodities including 

potato, cucumber, cantaloupe, lettuce, onion, tomato (fruit, paste, and puree), spinach, and wheat 

(forage, hay, straw, grain, bran, flour, shorts, germ, and middlings). HED concludes that this 

method is also suitable to enforce the new tolerances proposed in this petition. HED notes that 

since residues of fenamidone are detected through FDA Multi-Residue Method Protocol D, this 

protocol can also serve as an enforcement methodology.

Field trial data were generated using the enforcement method. The method has been adequately 

validated and acceptable for determining residues of fenamidone, and its metabolites RPA 

717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 in/on the commodities under 

consideration. The method extraction efficiency was validated by spiking control samples of 

each analyte which resulted in acceptable recoveries (70-120% range). The lowest level of 

method validation (LLMV) was 0.02 ppm for all analytes in all matrices.

Conclusions: The ILV and radiolabeled method validation were found adequate; therefore, the 

method is adequate for enforcement of the proposed new tolerances as it has met Agency’s 

standards. . 

5.1.4 Submittal of Analytical Reference Standards (860.1650)

The analytical reference standards for fenamidone (expiration date: 7/20/2014) and RPA 717879

(expiration date: 1/29/2016) have been submitted to the Agency’s Pesticide Repository (Email 

correspondence with Theresa M. Cole, US EPA National Pesticide Standard Repository, 

09/23/14). 

5.2 Storage Stability (860.1380)

MRIDs: 49052101, 49052102 and 49052103: “Fenamidone: Magnitude of the Residue on Ginseng, Lima, and snap 

beans, respectively”.

New storage stability studies were submitted for the tolerance petition on ginseng, lima and snap 

beans. In previously submitted and reviewed data (MRID 45385914), residues of fenamidone

and metabolites have been shown to be stable in various matrices. The submitted storage 

stability data have been validated and indicate that residues of fenamidone, RPA 717879 

(DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 are each relatively stable under frozen 

storage conditions for ~7 months in/on cottonseed and cotton gin byproducts, ~6 months in 

cottonseed hulls and meal, ~1 month in cottonseed oil, ~14 months in/on cucumber, ~13 months 

in/on leaf lettuce, ~12 months in/on bulb onions, ~13 months in/on potato tubers and in potato 

chips, ~12 months in potato flakes and potato wet peel, ~12 months in/on tomatoes, ~13 months 

in tomato paste and tomato puree, and ~13 months in/on wheat forage, grain, hay, and straw 

(45385914.der.doc). 
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The freezer storage stability study for ginseng indicated that fenamidone, and metabolites RPA 

717879 (DADK-Fen) and RPA 408056 (DA-Fen) were stable when stored frozen for 650 days.

However, concurrent freezer storage stability data were not provided for metabolite RPA 

405862. Therefore, the data presented is considered as supplemental only. 

For snap beans samples stored frozen for 360-361 and 830-831 days were within the acceptable 

70-120% range for all analytes except fenamidone in pod with seeds. Similarly, mean freezer 

storage recoveries in lima bean samples stored frozen for 250 and 804 days were within the 

acceptable 70-120% range for all analytes, indicating residues were stable for this time period.

These data are adequate to support the residue studies ginseng, lima and snap beans that are 

subject of this petition.

TABLE 6. Summary of Storage Conditions.

Matrix 

(RAC)

Storage 

Temperature

(°C)

Maximum Actual 

Storage Duration 

(days)1

Interval of Demonstrated Storage Stability

(days)

Dried ginseng 

roots

<-20 658 Dried ginseng roots were spiked with 0.2 ppm 

fenamidone, 0.4 ppm metabolite RPA 717879 

(DADK-Fen), and 0.2 ppm RPA 408056 (DAFen) and stored frozen for 650 days. The data 

indicated that fenamidone, and metabolites RPA 

717879 (DADK-Fen) and RPA 408056 (DA-Fen)

were stable when stored frozen for 650 days. 

Concurrent freezer storage stability data were not 

provided for metabolite RPA 405862.

Snap bean pods 

with seeds and 

snap bean plants 

with pods

≤-20 835 Snap bean pods with seeds and plants with pods 

were spiked with 0.2 ppm fenamidone or

metabolites RPA 408056 (DA-Fen), RPA 717879

(DADK-Fen), and RPA 405862. Samples were 

stored frozen for a minimum of 835 days, and 

there are no concerns regarding the stability of 

residues in snap bean pods with seeds, and snap 

bean plants with pods in this study.

Lima bean, seeds 

without pods

≤-20 682 Lima bean seeds were spiked with 0.2 ppm 

fenamidone or metabolites RPA 408056 (DAFen), RPA 717879 (DADK-Fen), and RPA 

405862. Samples were stored frozen for a 

maximum of 682 days, there are no concerns 

regarding the stability of residues in lima bean 

seeds without pods in this study.

1

From start of storage period to residue extraction. Residues were determined within 1 day of extraction.

Conclusions: The submitted storage stability results are adequate to support the storage duration 

for samples of lima and snap beans. Storage stability data for the degradate RPA 405862 were

not submitted and data in other root vegetables is not sufficient to support the storage duration of 

the ginseng crop field trial samples. However, since all the residues of concern other than RPA 

405862 were shown to be stable in ginseng, and RPA 405862 was shown to be stable in/on 

succulent beans samples which were stored for a longer period than the ginseng samples, 

additional residue data will not be required at this time.
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5.3 Residue Data

5.3.1 Crop Field Trials (860.1500)

Ginseng (MRID 49052101)

Five residue field trial studies were conducted to support the registration request for the use of 

fenamidone on ginseng. These studies were conducted in the 2007 growing season in the US and 

Canada. Fenamidone residues in dried ginseng roots treated with 9 foliar broadcast applications 

of fenamidone at total rates of 2.43-2.48 lbs a.i./A ranged from 0.02-0.53 ppm, when samples 

were harvested at 12-15 day PHIs and retreatment intervals from 12-15 days. Ginseng is a three 

to four years crop and therefore, in order to simulate the effects of multi-year applications on the 

residues, field trials were carried out using higher total application rate of fenamidone (2.48 lbs 

a.i./A) than that stated on the label (maximum yearly 0.80 lbs a.i./A). Residue decline data for 

carrot (representative commodity of ginseng crop subgroup) shows that residues of fenamidone 

increased as the PHI increased from 3 to 15 days and then drop slightly as the PHI increased to 

29 days (T. Bloem, D314118, 06/14/2007). In addition, the confined rotational study showed the 

presence of RPA 408056 (DA-Fen) and RPA 717879 (DADK-Fen). Turnips planted 30, 120, 

and 365 days following treatment of C-phenyl ring radiolabeled fenamidone at 1.80 lb ai/acre 

showed TRRs of 0.2501 ppm at 30 days, 0.1488 at 120 days, and 0.1381 ppm at 365 days in 

turnip roots (T. Bloem, D281887, see 45385902.der.wpd). In mature turnip root samples, RPA 

717879 (DADK-Fen) decreased from 0.0359 ppm at 30 day to 0.0204 ppm at 365 days, RPA 

408056 (DA-Fen) conjugate decreased from 0.3437 ppm at 30-days to 0.0857 ppm at 365 days. 

Actual uptake of residues of fenamidone from the soil may be lower as suggested by two field 

rotational studies with radish (T. Bloem, D281887, 07/1/2002). However, based on the confined 

rotational study with turnip and the decline data with carrot showing some persistence of 

residues of fenamidone, the crop field trial use pattern used on ginseng will be accepted at this 

time. 

The ginseng field trials showed that residues of metabolites RPA 408056 (DA-Fen), and RPA 

405862 ranged from <0.02-0.028, and from <0.02-0.024 ppm, respectively, while for RPA 

717879 (DADK-Fen) were all <0.02 ppm. Fenamidone residues in dried ginseng roots treated 

with 3 foliar broadcast applications of fenamidone at total rates of 0.817 lbs a.i./A ranged from 

0.049-0.059 ppm, when samples were harvested at a 14-day PHI. Residues of the metabolites 

RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were all <0.02 ppm and 

harvested at a 14-day PHI. Residue decline behavior was not assessed.

Table 7. Summary of Residue Data from Crop Field Trials with Fenamidone on 

Ginseng1.

Commodity Total Applic. 

Rate

lb a.i./A

PHI 

(days)

Residue Levels

(ppm)

n

2 Min. Max. LAFT* HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

Fenamidone

Dried Ginseng 

Roots 2.43-2.48 12-15 10 0.02 0.53 -- -- 0.15 0.19 0.16

5 -- -- 0.027 0.35 0.17 0.19 0.13
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Metabolite RPA 717879 (DADK-Fen)

Dried Ginseng 

Roots 2.43-2.48 12-15 10 <0.02 <0.02 -- -- <0.02 <0.02 0

5 -- -- <0.02 <0.02 <0.02 <0.02 0

Metabolite RPA 408056 (DA-Fen)

Dried Ginseng 

Roots 2.43-2.48 12-15 10 <0.02 0.028 -- -- <0.02 <0.021 0.0027

5 -- -- <0.02 <0.024 <0.02 <0.021 0.0018

Metabolite RPA 405862

Dried Ginseng 

Roots 2.43-2.48 12-15 10 <0.02 0.024 -- -- <0.02 <0.021 0.0015

5 -- -- <0.02 <0.022 <0.02 <0.021 0.0011

Total Residues

Dried Ginseng 

Roots

10 0.08 0.62 0.02 0.06

5 0.087 0.02 0.06

1

Summary statistics do not include data from Trial ID # MI29-03 since it was the only plot treated at a different 

total application rate. RPA 413255 was not measured in this study.

2 Where n=10, statistics are based on trial samples; where n=5, statistics are based on trial averages.

* LAFT = Lowest Average Field Trial; HAFT = Highest Average Field Trial.

Lima Beans (MRID 49052102)

Nine trials were conducted in the US in the 2008 growing season. Fenamidone, formulated as 

Reason 500 SC, was applied to succulent lima beans in 4 foliar broadcast applications at all trial 

sites at rates 0.259-0.278 lbs a.i./A, and RTIs of 6-9 days, for total application rates of 1.05-1.10 

lbs a.i./A. At the trial conducted in North Carolina (NC30), pods were slow to mature, so a fifth 

application was applied to lima beans to enable pod harvest at the requested PHI; therefore, the 

total application rate was 1.34 lbs a.i./A.

Fenamidone residues in succulent lima bean seeds without pods treated at total rates of 1.05-1.10 

lbs a.i./A ranged from <0.02-0.08 ppm when samples were harvested at 2-4 day PHIs. Residues 

of the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were all 

<0.02 ppm in lima bean seeds without pods treated at the same rate and harvested at the same 

PHI. At the trial conducted in North Carolina, residues of fenamidone, and metabolites RPA 

408056 (DA-Fen) and RPA 405862 were all <0.02 ppm in lima bean seeds without pods treated 

foliarly with a total of 1.34 lbs a.i./A when samples were harvested at a 4-day PHI. Residues of 

the metabolite RPA 717879 (DADK-Fen) were 0.04 ppm in both samples harvested from the 

North Carolina trial site. Residue decline behavior was not assessed.

TABLE 8. Summary of Residue Data from Crop Field Trials with Fenamidone on Lima 

Beans1.

Commodity Total Applic. 

Rate

lb a.i./A

PHI 

(days)

Residue Levels

(ppm)

n

2 Min. Max. LAFT* HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

Fenamidone

Lima bean 

seeds without 

pods

1.05-1.10

2-4 16 <0.02 0.08 -- -- <0.02 <0.04 0.024

8 -- -- <0.02 0.08 <0.03 <0.04 0.026

Metabolite RPA 717879 (DADK-Fen)

Lima bean 

seeds without 

pods

1.05-1.10

2-4 16 <0.02 <0.02 -- -- <0.02 <0.02 0

8 -- -- <0.02 <0.02 <0.02 <0.02 0
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Metabolite RPA 408056 (DA-Fen)

Lima bean 

seeds without 

pods

1.05-1.10

2-4 16 <0.02 <0.02 -- -- <0.02 <0.02 0

8 -- -- <0.02 <0.02 <0.02 <0.02 0

Metabolite RPA 405862

Lima bean 

seeds without 

pods

1.05-1.10

2-4 16 <0.02 <0.02 -- -- <0.02 <0.02 0

8 -- -- <0.02 <0.02 <0.02 <0.02 0

Total Residues

Lima bean 

seeds without 

pods

16 0.02 0.035 0.02 0.025

8 0.02 0.035 0.02 0.025

1

Summary statistics do not include data from Trial ID # NC30 since an additional application was applied resulting 

in a different total application rate.

2 Where n=16, statistics are based on trial samples; where n=8, statistics are based on trial averages.

* LAFT = Lowest Average Field Trial; HAFT = Highest Average Field Trial.

Snap Beans (MRID 49052103)

Eight trials were conducted in the US in the 2008 growing season. Fenamidone, formulated as 

Reason 500 SC, was applied to snap beans in 4 foliar broadcast or foliar directed applications, 

with RTIs of 6-8 days, for total application rates of 1.05-1.36 lbs a.i./A. A fifth application was 

added at the trial conducted in California (Trial ID # CA86) due to slow pod maturation; 

therefore, the total application rate was 1.36 lbs a.i./A.

Fenamidone residues in snap bean pods with seeds ranged from 0.084-0.46 ppm when snap 

beans were treated with 4 foliar applications of fenamidone and samples were harvested at 3-4 

day PHIs. Residues of the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and 

RPA 405862 were all <0.02 ppm. Fenamidone residues decreased with increasing PHI when 

snap bean pods with seeds were harvested at PHIs of 1, 3, 7, and 13 days. Residues of the 

metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were all <0.02 

ppm in snap bean pods with seeds at all PHIs. At the trial conducted at the higher rate of 1.52 kg 

a.i./ha (1.36 lbs a.i./A) (Trial ID # CA86), fenamidone residues in snap bean pods with seeds 

ranged from 1.07-1.52 ppm when samples were harvested at a 3-day PHI. Residues of the 

metabolites were all <0.02 ppm at this trial site.

Fenamidone residues in snap bean plants with pods ranged from 2.0-15.9 ppm when snap beans 

were treated with 4 foliar applications and samples were harvested at 3-4 day PHIs. Residues of 

the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 ranged 

from <0.02-0.042, 0.046-0.17, and <0.02-0.094 ppm, respectively. Fenamidone residues 

decreased with increasing PHI when snap bean plants with pods were harvested at PHIs of 1, 3, 

7, and 13 days (decline study). Residues of the metabolite RPA 717879 (DADK-Fen) were all 

<LOQ in residue decline samples. Average residues of the metabolite RPA 408056 (DA-Fen)

were higher at the 13-day PHI than they were in the samples harvested at the 1-day PHI. Average 

residues of the metabolite RPA 405862 appeared to stay about the same. At the trial conducted at 

the higher rate of 1.36 lbs a.i./A (Trial ID # CA86), fenamidone residues in snap bean pods with 

seeds ranged from 24-25 ppm when samples were harvested at a 3-day PHI. Average residues of 

the metabolites RPA 717879 (DADK-Fen), RPA 408056 (DA-Fen), and RPA 405862 were 

0.037, 0.096, and 0.11 ppm, respectively at the CA86 trial site.
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TABLE 9. Summary of Residue Data from Crop Field Trials with Fenamidone on Snap 

Beans1.

Commodity Total Applic. 

Rate

(kg a.i./ha)

[lb a.i./A]

PHI 

(days)

Residue Levels

(ppm)

n

2 Min. Max. LAFT* HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

Fenamidone

Snap bean 

pods with 

seeds 1.05-1.36

3-4 14 0.084 0.46 -- -- 0.19 0.23 0.13

7 -- -- 0.097 0.46 0.19 0.23 0.13

Snap bean 

plants with 

pods

14 2.0 15.9 -- -- 7.58 8.09 4.47

7 -- -- 2.3 15.9 7.58 8.09 4.63

Metabolite RPA 717879 (DADK-Fen)

Snap bean 

pods with 

seeds 1.05-1.36

3-4 14 <0.02 <0.02 -- -- <0.02 <0.02 0

7 -- -- <0.02 <0.02 <0.02 <0.02 0

Snap bean 

plants with 

pods

14 <0.02 0.042 -- -- <0.02 <0.023 0.008

7 -- -- <0.02 0.042 <0.02 0.023 0.008

Metabolite RPA 408056 (DA-Fen)

Snap bean 

pods with 

seeds 1.05-1.36

3-4 14 <0.02 <0.02 -- -- <0.02 <0.02 0

7 -- -- <0.02 <0.02 <0.02 <0.02 0

Snap bean 

plants with 

pods

14 0.046 0.17 -- -- 0.11 0.11 0.036

7 -- -- 0.047 0.17 0.11 0.11 0.037

Metabolite RPA 405862

Snap bean 

pods with 

seeds 1.05-1.36

3-4 14 <0.02 <0.02 -- -- <0.02 <0.02 0

7 -- -- <0.02 <0.02 <0.02 <0.02 0

Snap bean 

plants with 

pods

14 <0.02 0.094 -- -- 0.039 0.042 0

7 -- -- <0.02 0.094 0.039 0.043 0.025

1

Summary statistics do not include data from Trial ID # CA86 since an additional application was applied resulting 

in a different total application rate.

2 Where n=14, statistics are based on trial samples; where n=7, statistics are based on trial averages.

* HAFT = Highest Average Field Trial.

Onion, bulb, subgroup 3-07A

(T. Bloem, D297216, 05/25/04)

Tolerances are established for garlic, bulb; garlic, great headed; onion, dry bulb; and shallot, bulb 

at 0.20 ppm. These are based on eight dry bulb onion trials in which fenamidone was foliarly 

applied six times at a single application rate of 0.178 lb ai/A, 5-9 day RTI for a total rate of 1.05-

1.09 lb ai/A . Samples were pulled at 3 to 7 days post treatment and cured in the field for 0-6 

days prior to collection. The registrant proposes to use this data to establish a tolerance for 

onion, bulb, subgroup 3-07 A. Based on the similarity of the use pattern and adequacy of the 

data the registrant proposal is appropriate.
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Onion, green, subgroup 3-07B

(T. Bloem, D297216, 05/25/04)

Tolerances are established for onion, green; onion, welsh; leek; and shallot, fresh leaves at 1.5 

ppm. These are based on four green onion trials in which fenamidone was foliarly applied six 

times at a single application rate of 0.178 lb ai/A, 6-8 day RTI for a total rate of 1.06-1.08 lb 

ai/A. Samples were harvested at a 7-day PHI. The registrant proposes to use this data to 

establish a tolerance for onion, green, subgroup 3-07 B. Based on the similarity of the use 

pattern and adequacy of the data the registrant proposal is appropriate.

Conclusions 

The data presented here for the tolerance petition on ginseng, succulent beans, bulb onion 

(subgroup 3-07A), and green onion (subgroup 3-07B) are adequate. The residue data are 

supported by the storage stability and the analytical methods which were validated in the studies 

for both the parent and residues of concerns. Additionally, the number, geographical location and 

distribution of these crops were adequate to satisfy this tolerance petition. 

5.3.2 Field Rotational Crops (860.1900)

D357372, 2/24/09, A. LaMay

Rotational crop data have been submitted for field corn, sweet corn and soybeans and tolerances 

for inadvertent residues have been established. The rotational crop trials were considered 

adequate to support a plant back interval (PBI) of 30 days. Residues of conjugated RPA 405862

were not reported for field corn, sweet corn, or soybean rotation crops, but are a residue of 

concern in rotational crops for risk assessment purposes. In the absence of data on conjugated 

RPA 405862, HED translated information on the relative ratios of residues of conjugated RPA

405862 to RPA 717879 (DADK-Fen) from related crops to derive a conservative risk 

assessment. 

5.3.3 Processed Food and Feed (860.1520)

Field ginseng and lima/snap beans processing data were not submitted with this petition. For the 

purpose of this request for use on ginseng and lima/snap beans, detectable residues are not 

expected in processed commodities and tolerances for processed field ginseng and lima/snap 

beans commodities are not required. 

5.3.4 Meat, Milk, Poultry and Eggs (860.1480)

D314318, 6/14/2007, T. Bloem

Tolerances are currently established for livestock commodities. Cowpea forage and hay can be 

used as feed items to dairy cattle consisting of up to 20% of the diet. These feed items may

contribute to the roughage content of the diet. To maintain a reasonably balanced diet, the 

constructed diet for dairy cattle includes 45% roughage, 45% carbohydrate, and 10% protein

concentrate, consistent with the diet described in the Table 1 (June 2008) guidance. HED has 

previously calculated a dietary burden for dairy cattle to support new uses in several crops 

including turnip (D352806, D. Davis, 12/18/2008). A dietary burden of 30.17 ppm was 
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estimated for dairy cattle; however, the highest dose tested in the feeding study was 7.9 ppm 

which did not supported the new use in turnip. 

Considering the residue levels of fenamidone, RPA 717879 and RPA 408056 in/on cowpea hay

and forage a dietary burden of 22.1 ppm is estimated, see Table 5.

Table 4. Residue estimates for cowpea feedstuff commodities.

Commodity Fenamidone RPA 717879 RPA 408056 Residue (ppm)

Cowpea, hay115.9 ppm * 86/30 0.042 ppm * 86/30 0.17 ppm * 86/30 46.19

Cowpea, forage 15.9 ppm 0.042 ppm 0.17 ppm 16.11

1 Residue data for cowpea hay is not available; therefore, the maximum residues in/on snap bean forage were translated to 

cowpea forage and then adjusted by the % of dry matter to estimate the residues in/on cowpea hay.

Table 5. Dietary Burden Calculations for Dairy Cattle

Crop1,3 Residue 

(ppm)2

%Dry 

Matter2

% Diet Residue in Diet (ppm)

Dairy Cattle Dairy Cattle

Cowpea hay (R) 46.19 86 20 10.74

Cowpea forage (R) 16.11 30 20 10.74

Wheat hay (R) 3.16 88 5 0.18

Wheat milled byproducts (CC) 0.62 88 35 0.24

Carrot (CC) 0.17 12 10 0.14

Cottonseed meal (PC) 0.08 89 10 0.01

Total 22.1

1

 R= roughage; PC = protein concentrate; CC = carbohydrate concentrate.

2

 For wheat, combined fenamidone, RPA 717879, and RPA 408056 (free and conjugated); inadvertent residues in wheat as a 

result of crop rotation; for calculation see D297216, T. Bloem, 25-May-2004); for the other crops, combined fenamidone, RPA 

717879, RPA 408056, and RPA 405862 – highest field trial value used for combined residues.

3 Turnip roots and tops are not included based on a label restriction for the use of turnip commodities to fed livestock (D366172, 

D. Davis, 06/16/2009).

A lactating dairy cattle feeding study was previously submitted and reviewed by HED (D297216, 

T. Bloem, 25-May-2004). The cattle were dosed with fenamidone for 35 days at dietary feeding 

levels of 0.8 ppm, 2.3 ppm, and 7.9 ppm. Milk was collected throughout the study and muscle, 

fat, liver, and kidney were collected at sacrifice. Because of low residue levels, only samples 

from the 7.9 ppm dosing group were analyzed. Following dosing of cattle with fenamidone for 

35 days at 7.9 ppm, residues of fenamidone and its metabolites RPA 717879 and RPA 408056 

were below the limit of detection (LOD = <0.0033 ppm each) in milk samples collected over the 

course of the dosing period and were <LOD (<0.017 ppm each) in samples of muscle, fat, liver, 

and kidney collected at sacrifice. Quantifiable residues of fenamidone were observed in one 

sample of milk fat at 0.011 ppm; the other two samples bore detectable residues of fenamidone at 

levels below the LOQ (<0.01 ppm). Residues of RPA 717879 and RPA 408056 were <LOD 

(<0.0033 ppm each) in the milk fat samples. 

The current dietary burden for dairy cattle including the newly proposed use on succulent beans 

(i.e. including cowpea) would results in a dietary burden of 22.1 ppm which exceeds the highest 

dose tested in the lactating dairy cattle study by 2.8-fold. HED concludes that it is not possible 

to determine if revised milk and meat tolerances might be required as a result of feeding dairy

cattle cowpeas treated with fenamidone; therefore, HED does not consider the cowpea use 

adequately supported by residue data. 
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Conclusions: A cowpea hay and forage feeding restriction is not considered practical. A 

ruminant feeding study reflecting a concentration in the diet which brackets the newly calculated 

MRBD would be required to support a use on cowpeas. In the absence of an appropriate feeding 

study, HED would recommend to establish a tolerance for bean, succulent, except cowpea.

6.0 Tolerance Derivation

The Organization for the Economical Cooperation and Development (OECD) MRL calculation 

procedures were used to determine the tolerances for ginseng and succulent beans. The 

procedures generate tolerances based on mean field trial values. The spreadsheets for the various 

commodities can be found in Appendix C.

The tolerance for ginseng was determined by using the crop field trial representing the multi-year 

application. A tolerance of 0.8 ppm is recommended. For snap beans with seeds, the residue 

level from one field trial (CA86 Holtville, CA) was not included in the calculation for tolerance, 

mainly because an additional application was added to the crop due to slow pod maturation (1.36 

lbs a.i./A). A tolerance of 0.8 ppm is recommended. For lima beans, the residue level from one 

field trial (NC30) was not included in the calculation for tolerance, mainly because an additional

application was added to the crop due to slow pod maturation (1.34 lbs a.i./A). The tolerance for 

snap beans (pods with seeds) and lima beans was estimated separately as 0.15 ppm and 0.8 ppm, 

respectively. Since these estimated tolerances differ by a 5x factor, HED is in favor of 

establishing a tolerance of 0.8 ppm for succulent beans (except cowpea). 

HED recommends that the tolerances for onion, bulb, subgroup 3-07A and onion, green, 

subgroup 3-07B are established based on the current tolerances for the commodities under the 

respective groups in order to maintain harmonization with Canada; therefore, a reevaluation 

using the OECD procedures is not recommended at this time.

References

49052102.der.doc., Corley, J. (2012), Fenamidone: Magnitude of the Residue on Bean (Lima). 

49052103.der.doc, Corley, J. (2012), Fenamidone: Magnitude of the Residue on Bean (Snap).

49052101.der.doc, Corley, J. (2010), Fenamidone: Magnitude of the Residue on Ginseng.

Attachments

Appendix A. Field Trial Geographic Distribution

Appendix B. International Residue Limits Table

Appendix C. OECD MRL Calculation Procedure Inputs/Outputs
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Appendix A. Field Trial Geographic Distribution

TABLE 1 Trial Numbers and Geographical Locations.

NAFTA 

Growing 

Zones

Ginseng

Submitted Requested

Canada* U.S.

5 1 1

5A 3 --

11 -- 1

12 1 --

Total 5 2

* According to DIR98-02.

TABLE 2 Trial Numbers and Geographical Locations.

NAFTA 

Growing 

Zones

Snap beans

Submitted Requested

Canada* U.S.

1 1 --

1A -- 1

2 1 --

3 1 --

5 -- 2

5A 3 --

5B -- 2

10 1

1

--

12 1 --

Total 8 5

* Trial requirements in DIR98-02 are listed for “green or wax beans”.

1 The trial at this site was conducted at a higher rate than the other trials.

TABLE 3 Trial Numbers and Geographical Locations.

NAFTA 

Growing 

Zones

Lima beans

Submitted Requested

Canada* U.S.

1A -- 1

2 5

1

--

5 -- 2

5A 1 --

5B -- 2

10 2 --

11 1 --

Total 9 5

* Trial requirements in DIR98-02 are listed for “green or wax beans”.

1 An additional application was applied at one trial site resulting in a different total application rate compared to all 

other trials.
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Appendix B. International Residue Limits Table

Table B1. Summary of US and International Tolerances and Maximum Residue Limits for 

Fenamidone (PC Code: 046679)

Residue Definition:

US Canada Mexico2 Codex

40 CFR 180.579:

Plants: fenamidone (4H-Imidazol-4-one, 3,5-dihydro-5-

methyl-2-(methylthio)-5-phenyl-3 (phenylamino)-, (S)-) 

Livestock: fenamidone (4H-imidazol-4-one, 3,5-dihydro5-methyl-2-(methylthio)-5-phenyl-3-(phenylamino), (S)-) 

and its metabolite RPA 717879 (DADK-Fen) (2,4-

imidazolidinedione, 5-methyl-5-phenyl), expressed as 

parent compound

Indirect or inadvertent residues:. fenamidone (4-Himidazol-4-one, 3,5-dihydro-5-methyl-2-(methlthio)-5-

phenyl-3-(phenylamino, (S)-) and its metabolite RPA 

717879 (DADK-Fen) (2,4-imidazolidinedione, 5-methyl5-phenyl)

(5S)-3,5-dihydro-5-

methyl-2-

(methylthio)-5-

phenyl-3-

(phenylamino)-4Himidazol-4-one

None

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico2 Codex

Ginseng 0.8 0.15 ginseng roots3

Beans, Succulent, except 

cowpea

0.8

Onion, bulb, subgroup 03-07A 0.20

0.2 Chinese, onions; Daylilies; dry 

bulb onions; fritillaria, bulbs; garlic; 

great-headed garlic; lilies; pearl 

onions, potato onions; serpent 

garlic, shallot bulbs

onion, green, subgroup 03-07B 1.5

1.5 Beltsville bunching onions, 

elegans hosta, fresh (Chinese chive 

leaves, chive leaves), fresh onions, 

fritillaria leaves, green onions, 

kurrats, lady's leek, leeks, 

macrostem onions, shallot leaves, 

tree onion tops, Welsh onion tops, 

wild leeks

Completed: M. Negussie; 09/16/2013

1

Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3

Identical regulatory levels are recommended by EPA and PMRA as part of this joint review (0.08 ppm).
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Appendix C. OECD MRL Calculation Procedure Inputs/Outputs

Compound Fenamidone Fenamidone Fenamidone Fenamidone

Crop

Ginseng Lima Beans

Snap beans 

(pots with 

seeds)

Snap Beans 

(plants 

with pods)

Region / Country USA USA USA USA

GAP 2.78 1.1 1.36 1.36

Total number of 

data (n) 5 8 7 7

Percentage of 

censored data 0% 50% 0% 0%

Number of noncensored data 5 4 7 7

Lowest residue 0.027 0.020 0.100 2.300

Highest residue 0.350 0.080 0.460 15.900

Median residue 0.170 0.020 0.190 7.580

Mean 0.186 0.039 0.234 8.101

Standard 

deviation (SD) 0.134 0.026 0.132 4.647

Correction 

factor for 

censoring (CF) 1.000 0.667 1.000 1.000

Proposed MRL 

estimate

- Highest 

residue 0.350 0.080 0.460 15.900

- Mean + 4 SD 0.721 0.144 0.764 26.690

- CF x 3 Mean 0.559 0.078 0.703 24.304

Unrounded MRL 0.721 0.144 0.764 26.690

Rounded MRL 0.8 0.15 0.8 30

High 

uncertainty 

of MRL 

estimate 

due to 

small 

dataset.

High 

uncertainty 

of MRL 

estimate 

due to high 

level of 

censoring.

High 

uncertaint

y of MRL 

estimate 

due to 

small 

dataset.

High 

uncertaint

y of MRL 

estimate 

due to 

small 

dataset.
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Residues 

(mg/kg)

Residues 

(mg/kg)

Residues 

(mg/kg)

Residues 

(mg/kg)

0.170 0.020 0.110 2.300

0.095 0.020 0.280 5.600

0.027 0.080 0.460 15.900

0.290 0.040 0.160 11.000

0.350 0.080 0.100 4.130

0.020 0.340 7.580

0.020 0.190 10.200

0.030

Note: If an acceptable feeding study is submitted a tolerance of 30 ppm would be appropriate for 

cowpea forage based on the data for snap beans (plants with pods).
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Appendix D: Chemical Structures

Name Structure

Fenamidone; RPA 407213

(5S)-3,5-dihydro-5-methyl-2-(methylthio)-5-phenyl-3-

(phenylamino)-4H-imidazol-4-one

DA-Fen; RPA 408056 (racemic mixture)

5-methyl-2-methylthio-5-phenyl-3,5-dihydroimidazol-4-

one

RPA 405862 (racemic mixture)

RPA 410193 (S enantiomer)

5-methyl-5-phenyl-3-phenylamino-imidazolidin-2,4-dione

DADK-Fen; RPA 717879 (racemic mixture)

5-methyl-5-phenylimidazolidine-2,4-dione

RPA 413255

(5S)-5-methyl-2-(methylthio)-3-[(2-nitrophenyl)amino]-5-

phenyl-3,5-dihydro-4H-imidazol-4-one

RPA 410914 (racemic mixture)

N

N

CH3

O S

CH3

N

H

N

N

CH3

O S

CH3

H

N

H

N

CH3

O O

N

H

N

H

N

CH3

O O

H