                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460      

                                                     	OFFICE OF CHEMICAL SAFETY
                                                                                                       	 AND POLLUTION PREVENTION	



MEMORANDUM

Date:  27-OCT-2011

SUBJECT:	Difenoconazole.  Amended Section 3 Registration (Dividend(R) Fungicide) to Add Seed Treatment Uses on Oats and Rye and Establish Tolerances in/on Oat Commodities, Rye Commodities, and Wheat Hay.  Summary of Analytical Chemistry and Residue Data.

PC Code:  128847
DP Barcodes:  384073
Decision Nos.:  440121
Registration No.: 100-740
Petition Nos.:  0F7785
Regulatory Action:  Amended Section 3 Registration
Risk Assessment Type:  Not Applicable
Case No.:  7014
TXR No.:  Not Applicable
CAS No.:  119446-68-3 
MRID No.:  None
40 CFR:  180.475
		              									

FROM:	Bonnie Cropp-Kohlligian, Environmental Scientist
		Risk Assessment Branch 4
		Health Effects Division (7509P)		
		
THROUGH:	Susan V. Hummel, Chemist/Senior Scientist
		Risk Assessment Branch 4
		Health Effects Division (7509P)
	
TO:		Rosemary Kearns/Tony Kish (RM 22)
		Fungicide Branch
		Registration Division (7505P)
	
Difenoconazole is a broad spectrum fungicide belonging to the triazole group of fungicides (Group 3) that acts by inhibiting sterol demethylation.  It is currently registered in the U.S. for use as a seed treatment on barley, canola, cotton, sweet corn, wheat, and triticale.  It is also currently registered in the U.S. for foliar applications on numerous crops, but not cereal grains. 

Tolerances for difenoconazole in/on plant commodities are currently established under §180.475(a)(1) and are expressed in terms of difenoconazole per se.  Tolerances are established for numerous raw agricultural and processed commodities ranging from 0.01 ppm to 35 ppm; including tolerances for barley grain (0.1 ppm), barley hay (0.05 ppm), barley straw (0.05 ppm), wheat grain (0.1 ppm), wheat forage (0.1 ppm), and wheat straw (0.1 ppm).  Import tolerances are also established for a number of raw agricultural commodities (RACs), including rye grain (0.1 ppm).  [Note:  In accordance with 40 CFR 180.1(g), tolerances established in/on wheat RACs apply to triticale RACs.]      

Tolerances for difenoconazole on livestock commodities are currently established under §180.475(a)(2) and are expressed in terms of difenoconazole and its metabolite, CGA-205375 [1-[2-chloro-4-(4-chloro-phenoxy)phenyl]-2-[1,2,4]triazol-1-yl-ethanol].  Tolerances are established for tissue, milk, and egg ranging from 0.01ppm to 0.20 ppm.

Under PP# 0F7785, Amended Section F submitted to T. Kish (via email from R. Rezaaiyan dated 4/27/11), Syngenta Crop Protection, Inc. (hereafter referred to as Syngenta) is proposing the establishment of tolerances for residues of difenoconazole [1-[2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole] in/on the following raw agricultural commodities:

            Oats, grain	0.1 ppm
            Oats, forage	0.1 ppm
            Oats, hay	0.1 ppm
            Oats, straw	0.1 ppm
            Rye, grain[1]	0.1 ppm
            Rye, forage	0.1 ppm
            Rye, straw	0.1 ppm
            Wheat, hay	0.1 ppm
            [1]Note that although difenoconazole is not currently registered in the U.S. for use on rye, an import tolerance is currently established under 40 CFR §180.475(a)(1) for residues of difenoconazole in/on rye grain at 0.1 ppm.  

In conjunction with PP#0F7785, Syngenta is requesting an amended Section 3 registration for a 3.1 lb/gal flowable concentrate for seed treatment (FS) formulation (Dividend(R) Fungicide; EPA Reg. No. 100-740) to add seed treatment uses on oats and rye at a maximum use rate of 11 g ai/100 lb seed; the same use currently registered in the U.S. on other cereal grain seed, including barley, wheat, and triticale.  There is a proposed restriction for the grazing of green oat and rye forages until 55 days after planting on the submitted proposed label but not on Section B of the petition; this same restriction is currently registered for the grazing of green wheat and triticale forages.  

No new residue chemistry data were submitted with the current petition.  Instead the petitioner has requested the translation of available wheat and barley magnitude of the residue data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.  These data have been re-evaluated herein primarily for the purposes of harmonization and secondarily for the purposes of setting tolerances in accordance with current guidance.  [Note:  Since no new residue chemistry data were submitted, only the subject wheat and barley field trial data have been discussed in depth under Detailed Consideration.] 
 
Because difenoconazole is a triazole compound, HED requires that samples from any metabolism, field trial, and/or processing study be analyzed for the triazole metabolites triazolylalanine (TA), triazolyl acetic acid (TAA), and 1,2,4-triazole (1,2,4-T).  HED issued guidance on the residue chemistry data requirements for the triazole-based metabolites under DP# 327788 (4/25/06, M. Doherty).  The supporting barley and wheat magnitude of the residue data consider herein were submitted prior to the HED issued guidance, and do not include any triazole metabolite data.  This issue will not be discussed further. 

It is important to note that the first food use of difenoconazole, which was reviewed under a previous petition, PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola), was for the establishment of import tolerances in/on barley, rye, and wheat resulting from seed treatment uses of difenoconazole on rye and wheat at 27.2 g ai/100 lb seed and on barley at 10.2 g ai/100 lb seed.  Hence, taking into account the proposed maximum seed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley, rye, wheat, and triticale (both domestic (Dividend(R) Fungicide (EPA Reg. No. 100-740)) and non-domestic (use information previously provided under PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola)), HED has evaluated the available data for the following maximum seed treatment use rates:  27.2 g ai/100 lb seed for the rye, wheat, and triticale and 11 g ai/100 lb seed for barley and oats.  

The nature of the residue in plants is understood based on acceptable plant metabolism studies reflecting foliar applications in canola, grape, potato, tomato, and wheat, and seed treatment in wheat.  HED concludes that the residue of concern for both tolerance enforcement and risk assessment for crops included in this petition is difenoconazole per se.  The nature of the residue in livestock is understood based on acceptable goat and hen metabolism studies.  The residues of concern for both tolerance setting and risk assessment for livestock commodities are difenoconazole per se and its metabolite CGA-205375.

An adequate tolerance enforcement method, Method AG-575B, is available for crop commodities.  The method determines residues of difenoconazole per se in/on crop commodities by gas chromatography with nitrogen-phosphorus detection (GC/NPD).  The method limits of quantitation (LOQs) range from 0.01-0.05 ppm.  A confirmatory GC method with mass-selective detection (MSD) is also available for crop commodities.

An adequate tolerance enforcement method, Method REM 147.07b, is available for livestock commodities.  The method determines residues of difenoconazole and CGA-205375 in livestock commodities by liquid chromatography with tandem mass spectrometry detection (LC/MS/MS).  The method LOQs are 0.01 ppm (for each analyte) for livestock tissues and 0.005 ppm (for each analyte) for milk.  Adequate confirmatory methods, Method AG-544A and Method REM 147.06, are available for the determination of residues of difenoconazole and CGA-205375, respectively, in livestock commodities. 

Adequate cattle and poultry feeding studies are available for difenoconazole, and tolerances for difenoconazole residues of concern in livestock commodities were recently re-evaluated in conjunction with a petition for tolerances in/on carrots, chickpeas, soybeans, stone fruits, strawberries, and turnip greens (PP# 9F7676; DP# 378829, 2/23/11, B. Cropp-Kohlligian).  Using the Agency's most recent guidance on constructing reasonably balanced livestock diets (ChemSAC memo, 6/30/08), the maximum dietary burdens (MDB) of livestock for difenoconazole residues were calculated to be 6.0 ppm for beef cattle, 1.6 ppm for dairy cattle, 0.09 ppm for swine, and 0.11 ppm for poultry.   These diets included barley and wheat livestock feedstuffs.  Although there are several livestock feedstuffs associated with the proposed uses on oats and rye, the reviewer has determined that they will not increase the dietary exposure of livestock to difenoconazole residues and that reassessment of livestock tolerances is not required for this petition. 

No oats and rye field trial data were submitted with the current petition (PP#0F7785).  Instead the petitioner has requested the translation of previously submitted wheat and barley field trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.  Given the deliberations by ChemSAC (meetings of 11/25/09 and 9/1/10) on this subject, the requested translations are deemed appropriate since the seed treatment uses under consideration are substantially similar to those reflected in the available wheat and barley field trial data and the resulting residues were either nondetectable (grain and hay), negligible (straw), or very low (forage) in/on the raw agricultural commodities (RACs) of wheat and barley.  Hence, barley grain data may be translated to oat grain since barley and oat grains are kernels (caryopsis) plus hulls (lemma and palea); wheat grain data may be translated to rye grain since rye and wheat grains are kernels with hulls removed.  Wheat forage data may be translated to oat and rye forage.  Wheat straw data may be translated to oat and rye straw.  Wheat hay may be translated to oat hay.

For grains, no detectable residues of difenoconazole were found in/on any of the wheat and barley grain samples collected from the supporting field trials.  Most of these data were collected with the current enforcement method, Method AG-575B (GC/NPD), or a substantially similar precursor (Method AG-575), having a LOQ of 0.01 ppm in/on grain.  However, a limited number of the older wheat grain data submitted with the first food use of difenoconazole (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola) from trials conducted in Europe (France (5 trials) and Germany (4 trials)) were generated with other, less sensitive data collection methods, precipitating the earlier recommendation to establish tolerances for residues of difenoconazole in/on barley grain, rye grain, and wheat grain at the higher current levels, 0.1 ppm.  These established tolerance levels are based primarily on wheat grain samples from trials conducted in France at the maximum seed treatment use rate for wheat (27.2 g ai/100 lb seed) in which residues in/on grain samples were reported as nondetectable, <0.02 ppm; below the reported "limit of sensitivity" of the data collection method (0.02 ppm in/on grain).  The original HED reviewer of these data (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola) determined that the demonstrated limit of detection, 0.08 ppm in/on grain, was higher than the reported "limit of sensitivity" (0.02 ppm in/on grain) based on the recovery data; hence, a tolerance level of 0.1 ppm was established.  Having re-evaluation the chromatograms for the grain samples collected from the trials conducted in France and Germany, the reviewer finds that residues of difenoconazole in/on the treated grain samples were not greater than those in/on the associated untreated grain samples.  Hence, taking into account all of the available evidence, the reviewer finds that no detectable residues of difenoconazole (i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), are expected in/on the grains of barley, oats, rye, and wheat from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  Therefore, the tolerances proposed by the petitioner for oat grain (0.1 ppm) and rye grain (0.1 ppm) are too high; tolerances of 0.01 ppm are appropriate. 

For hay and straw, having re-evaluated the previously submitted wheat hay and straw data, the reviewer finds that residues of difenoconazole are not expected to exceed 0.05 ppm (the LOQ of the current enforcement method for hay and straw) in/on barley hay, barley straw, oat hay, oat straw, rye straw, wheat hay, and wheat straw from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  Therefore, the tolerances proposed by the petitioner for oat hay (0.1 ppm), oat straw (0.1 ppm), rye straw (0.1 ppm), and wheat hay (0.1 ppm) are too high; tolerances of 0.05 ppm are appropriate.

For forage, having re-evaluated the previously submitted wheat forage data, and using the OECD MRL calculator, the reviewer finds that the available data will support a tolerance of 0.15 ppm in/on oat, rye, and wheat forages.  Residues of difenoconazole are not expected to exceed 0.15 ppm in/on oat, rye, and wheat forages from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  Therefore, the tolerances proposed by the petitioner for oat forage (0.1 ppm) and rye forage (0.1 ppm) are too low; tolerances of 0.15 ppm are appropriate.  Pregrazing and/or preharvest intervals are not needed for barley forage which is not considered a raw agricultural commodity (RAC) of barley.  Pregrazing and/or preharvest intervals are not needed for oat, rye, and wheat forages given that the use pattern is limited to seed treatment and the supporting wheat forage data collected at 34- to 61-days after planting, which were used to set tolerances in/on oat, rye, and wheat forages, reasonably reflect the shortest period possible between planting and grazing/harvesting these forages.

No oat and rye processing data were submitted with the current petition and none are available.  A wheat processing study (MRID 42090055) was previously submitted and reviewed by HED (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola).  Spring wheat seed was treated at 23.2 g ai/100 lb seed and planted.  Later the wheat was also treated twice foliarly with an emulsifiable concentrate (EC) formulation of difenoconazole at 100 g ai/A to attempt to achieve detectable residue in/on grain.  [Note:  Difenoconazole is not registered in the U.S. for foliar uses on cereal grains.]  Wheat grain was harvested 28 days after the last foliar treatment and processing into bran, middlings, shorts and germ, and patent flour.  No residues of difenoconazole (<0.01 ppm) were detected in the grain and processed commodities.  These data may be translated to the processed commodities of barley, oats, and rye given the nature of the subject wheat processing study which was conducted at an exaggerated rate resulting in nondetectable residues in both the RAC and processed commodities and given the use pattern for these cereal grains.  Hence, based on the available wheat processing data, tolerances in the processed commodities of barley, oats, rye, wheat, and triticale are not needed for the seed treatment uses under consideration.   

Previously submitted confined rotational crop data are adequate to support the proposed seed treatment uses of difenoconazole on oats and rye.  A 30-day plantback interval is appropriate for the proposed uses on these crops.  [Note:  Additional confined rotational crop data have been required to support foliar uses of difenoconazole but are not required to support the proposed seed treatment uses.  These data have been submitted (MRID 48203402) and are under review in HED (D382946).] 

Codex maximum residue limits (MRLs) for residues of difenoconazole have been established.  However, since no Codex MRLs have been established for residues of difenoconazole in/on oat commodities, rye commodities, and wheat hay, harmonization with Codex is not an issue.  Canadian MRLs for residues of difenoconazole have been established at 0.01 ppm for oat grain and 0.01 ppm for rye grain and harmonization with these established Canadian MRLs is recommended.  Mexican MRLs for residues of difenoconazole have been established; however, no Mexican MRLs have been established for any of the cereal grain commodities.  

I.	CONCLUSIONS

HED has examined the residue chemistry database for difenoconazole and pending submission of a revised Section F (see requirements under Proposed Tolerances), there are no residue chemistry issues that would preclude granting a registration for the requested seed treatment uses of difenoconazole on oats and rye or establishment of tolerances for residues of difenoconazole only in/on the raw agricultural commodities listed below.  Furthermore, pregrazing restrictions on forages are not needed for the requested seed treatment uses (see Directions for Use). 

            Oat, grain	0.01 ppm
            Oat, forage	0.15 ppm
            Oat, hay	0.05 ppm
            Oat, straw	0.05 ppm
            Rye, grain	0.01 ppm
            Rye, forage	0.15 ppm
            Rye, straw	0.05 ppm
            Wheat, hay	0.05 ppm
            
Notes to the PM:  

(1) The recommended tolerance for rye grain (0.01 ppm) should replace the existing import tolerance for rye grain (0.1 ppm).

(2) Having re-evaluated the available barley and wheat magnitude of the residue data which were translated to support the proposed seed treatment uses of difenoconazole on oats and rye, HED finds that, with regards to the maximum seed treatment uses of difenoconazole on barley, wheat, and triticale:  (i) the existing permanent tolerances for residues of difenoconazole in/on barley hay (0.05 ppm) and barley straw (0.05 ppm) are appropriate; (ii) the existing permanent tolerance for residues of difenoconazole in/on barley grain may be decreased from 0.1 ppm to 0.01 ppm to harmonize with the existing Canadian MRL (iii) the existing permanent tolerance for residues of difenoconazole in/on wheat grain may be decreased from 0.1 ppm to 0.02 ppm to harmonize with the existing Codex MRL; (iv) the existing permanent tolerance for residues of difenoconazole in/on wheat straw may be decreased from 0.1 ppm to 0.05 ppm consistent with the tolerances recommended for oat and rye straw; and (v) the existing permanent tolerance for residues of difenoconazole in/on wheat forage should be increased from 0.1 ppm to 0.15 ppm consistent with the tolerances recommended for oat and rye forages.  
 

860.1200 Directions for Use

   * Pregrazing restrictions are not needed for barley, oat, rye, and wheat forages and should be removed from the proposed and currently registered Dividend(R) Fungicide (EPA Reg. No. 100-740) labels.  [Note:  Pregrazing restrictions were not included in Section B of petition PP#0F7785.]


860.1550 Proposed Tolerances

   * The proposed tolerances should be revised to reflect the recommended tolerance levels and correct commodity definitions as specified in Table 3. 
 

II.	DETAILED CONSIDERATIONS

Background

Difenoconazole is a broad spectrum fungicide belonging to the triazole group of fungicides (Group 3) that acts by inhibiting sterol demethylation. 

The chemical structures and nomenclature of difenoconazole are presented in Table 1 and the physicochemical properties of the technical grade of difenoconazole are presented in Table 2. 
 

Table 1.   Structures and Nomenclature.  
Chemical structure of difenoconazole
                                       
Common name
Difenoconazole
Company experimental name
CGA-169374
IUPAC name
1-({2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3-dioxolan-2-yl}methyl)-1H-1,2,4-triazole
CAS name
1-[[2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3-dioxolan-2-yl]methyl]- 1H-1,2,4-triazole
CAS registry number
119446-68-3
End-use products (EP)
Dividend(R) Fungicide, 3.1 lb/gal FS (EPA Reg. No. 100-740).


Table 2.  Physicochemical Properties of Difenoconazole.
Parameter
Value
Reference
Melting point
78.6 ºC
DP#s 172067 and 178394, 10/26/92, R. Lascola
pH
6-8 at 20 ºC (saturated solution)

Density
1.37 g/cm[3] at 20 ºC

Water solubility
3.3 ppm at 20 ºC

Solvent solubility
	g/100 mL at 25 ºC:
n-hexane:	0.5
1-octanol:	35
toluene:	77
acetone:	88
ethanol:	89

Vapor pressure
2.5 x 10[-10] mm Hg at 25 ºC

Dissociation constant, pKa
1.1 for pure grade (99.3% +- 0.3%) difenoconazole in water (with 4% methanol) at 20ºC   
DP# 375159, 5/26/10, B. Cropp-Kohlligian
Octanol/water partition coefficient, Log(KOW)
4.2 at 25 ºC
DP#s 172067 and 178394, 10/26/92, R. Lascola
UV/visible absorption spectrum
max at about 200 and 238 nm (in methanol at 26 ºC)
PMRA Proposed Regulatory Decision Document on Difenoconazole, 4/14/99 (PRDD99-01)



860.1200 Directions for Use
Residue Chemistry Memo:  PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola

Dividend(R) Fungicide (EPA Reg. No. 100-740; EPA accepted 10/22/10) is a systemic seed dressing, formulated as a flowable concentrate for seed treatment (FS) containing 3.1 lb/gal (32.8%) of difenoconazole, which controls or suppresses certain seed-borne, soil-borne, and early season foliar diseases of wheat, barley, and triticale, and certain seed and seedling diseases of canola, sweet corn, and cotton.   Applications are made as water-based slurry though standard slurry or mist-type seed treatment equipment.  Tank mixed with other seed treatment products is permitted.  The use of an EPA-approved dye or colorant that imparts an unnatural color to seed is required.  Also bags containing treated seed are to be labeled with the following restrictive language:  (1) Do not use for feed, food, or oil purposes; (2) Store away from feeds and foodstuffs; (3) Green wheat or triticale forage may not be grazed until 55 days after planting; (4) Green barley forage may not be grazed until 30 days after planting; and (5) Do not plant any crop other than those on this label within 30 days to fields in which treated seeds were planted.     

In conjunction with the current petition (PP#0F7785) Syngenta is requesting an amended registration for Dividend(R) Fungicide (EPA Reg. No. 100-740) to add use as a seed treatment on oats and rye at 11 g ai/100 lb seed, the same maximum use rate it is currently registered on barley, wheat, and triticale.  The petitioner has submitted a Section B reflecting proposed use rates for the 3.1 lb/gal FS formulation (Dividend(R) Fungicide; EPA Reg. No. 100-740) on oats and rye without any additional restrictive language; supporting draft labeling (dated 9/20/10) was also submitted.  Consistent with the currently registered grazing restrictions for green wheat and triticale forage, the proposed label restricts the grazing of green oats and rye forage until 55 days after planting.
    
It is important to note that non-domestic seed treatment uses of difenoconazole on barley, rye, and wheat have been previously considered by the Agency and are different from the registered/proposed domestic use rates.  The first food use of difenoconazole, which was reviewed under a previous petition (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola), was for the establishment of import tolerances in/on barley, rye, and wheat resulting from seed treatment uses of difenoconazole on barley reported to the Agency at 10.2 g ai/100 lb seed, and on rye and wheat at 27.2 g ai/100 lb seed.  While the reported non-domestic maximum seed treatment use rate on barley is slightly less than the currently registered domestic maximum use rate, the reported non-domestic maximum seed treatment use rates on rye and wheat are roughly 2.5x higher than the proposed domestic maximum use rate on rye and the currently registered domestic maximum use rate on wheat.
 
Conclusions.   The proposed use directions are adequate to allow evaluation of the residue data relative to the proposed uses of difenoconazole on oats and rye.  No oats and rye field trial data were submitted with the current petition (PP#0F7785).  Instead the petitioner has requested the translation of previously submitted wheat and barley field trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.  

The maximum proposed seed treatment use rate for oats and rye is 11 g ai/100 lb seed, the same maximum use rate currently registered for barley, wheat, and triticale.  Based on the use of an EPA-approved dye or colorant to impart an unnatural color to the treated seed and the equipment used for application, the use appears limited to commercial facilities although this is not specified on the proposed Dividend(R) Fungicide (EPA Reg. No. 100-740) label.

It is important to note that non-domestic seed treatment uses of difenoconazole on barley, rye, and wheat have been previously considered by the Agency and are different from the registered/proposed domestic use rates.  The first food use of difenoconazole, which was reviewed under a previous petition (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola), was for the establishment of import tolerances in/on barley, rye, and wheat resulting from seed treatment uses of difenoconazole on barley reported to the Agency at 10.2 g ai/100 lb seed and on rye and wheat at 27.2 g ai/100 lb seed.

Taking into account the proposed maximum seed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley, rye, wheat, and triticale (both domestic (Dividend(R) Fungicide (EPA Reg. No. 100-740) and non-domestic (use information previously provided under PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola)), HED will evaluate available data for the following maximum seed treatment use rates:  27.2 g ai/100 lb seed for the rye, wheat, and triticale and 11 g ai/100 lb seed for barley and oats. 

Based on the available data, pregrazing restrictions are not needed for barley, oat, rye, and wheat forages and should be removed from the proposed and currently registered Dividend(R) Fungicide (EPA Reg. No. 100-740) labels.



860.1500 Crop Field Trials
Residue Chemistry Memos:
PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola (MRIDs 42090055 and 42090056)
PP#2F4107; DP#s 248285 and 248419, 10/28/98, S. Chun (MRID 44602001)
PP#6F4748; DP# 228403, 9/23/96, G. Kramer (MRID 44056001)

No oats and rye field trial data were submitted with the current petition (PP#0F7785).  Instead the petitioner has requested the translation of available acceptable wheat and barley field trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.  The available wheat and barley field trial data reflecting seed treatment use of difenoconazole have been re-evaluated and are discussed below. 

Wheat field trial data (MRIDs 4209055 and 4209056) conducted in the U.S. and Europe were submitted for the first food use of difenoconazole and reviewed under a previous petition, PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola).  Later, a new and substantially complete set of wheat field trial data (MRID 44602001) were submitted under another petition, PP#2F4107 (DP#s 248285 and 248419, 10/28/98, S. Chun).  Barley field trial data (MRID 44056001) were submitted under yet another petition, PP#6F4748 (DP# 228403, 9/23/96, G. Kramer).  Related data deficiencies were addressed over a period of several years under a number of HED reviews.

Wheat Field Trials

MRID 42090055  -  Data previously submitted and reviewed by HED under PP#2E4051 
(DP#s 172067 and 178394, 10/26/92, R. Lascola)

Spring wheat seed was treated with difenoconazole at either 11 or 23.2 g ai/100 lb seed and planted at 3 sites (ND (1), WA (1), and MT (1))  Spring wheat seed was treated with difenoconazole at 11 g ai/100 lb seed and planted at 3 sites (MN (1), SD (1), and IL (1)).  Plants were grown to maturity; forage samples were collected 54-92 days after planting, and grain and straw samples were collected 81-119 days after planting.  Samples were analyzed with an acceptable data collection method (Method AG-575 (GC/NPD)); based on recovery data the demonstrated LOQ was 0.01 ppm for grain, forage, and straw.  No detectable residues (<0.01 ppm) of difenoconazole were found in/on any of the grain or straw samples.  No detectable residues (<0.01 ppm) were found in/on forage in 5 of the 6 trials; only the SD trial, conducted at 11 g ai/100 lb seed, showed any detectable residues (0.02 ppm).

Winter wheat seed was treated with difenoconazole at either 9.5 or 21.2 g ai/100 lb seed and planted at 5 sites (NY (1), AR (1), TX (1), OK (1), and WA (1)).  Winter wheat seed was treated with difenoconazole at 9.5 g ai/100 lb seed and planted at 1 site (KS (1)).  Spring wheat seed was treated with difenoconazole at 9.5 or 21.2 g ai/100 lb seed and planted at 2 sites (AZ (1) and CA (1)).  This corresponds to 7 trials in the following regions:  Region 1 (1 trial), Region 4 (1 trial), Region 6 (2 trials), Region 8 (1 trial), Region 10 (2 trials), and Region 11 (1 trial).  Forage samples were collected 56-67 days after planting, and grain and straw samples were collected 149-328 days after planting.  Forage samples from CA, OK, and WA were not viable for various reasons.  Samples were analyzed with an acceptable data collection method (Method AG-575 (GC/NPD)); based on recovery data the demonstrated LOQ was 0.01 ppm for grain, forage, and straw.  No detectable residues (<0.01 ppm) of difenoconazole were found in/on any of the samples with the following exceptions:  (1) for forage, detectable residues (<=0.02 ppm) were found at the NY and AR trials and (2) for straw, detectable residues (<=0.03 ppm) were found at the AR, TX, and AZ trials.

MRID 42090056  -  Data previously submitted and reviewed by HED under PP#2E4051
(DP#s 172067 and 178394, 10/26/92, R. Lascola)
 
European Trials.  Residues trials were conducted in France (5 trials) and Germany (4 trials) using wheat, barley, or rye seed treated with difenoconazole.  In France, wheat seeds were treated at 8.2 g ai/100 lb seed (1 trial), 16.4 g ai/100 lb seed (1 trial), or 27.3 g ai/100 lb seed (3 trials) and grain samples were collected.  In Germany, wheat seed (1 trial), barley seed (2 trials), and rye seed (1 trial) were treated at 27.3 g ai/100 lb seed and grain, forage, and straw samples were collected.  No detectable residues of difenoconazole were reportedly found in/on any of the grain and straw samples; detectable residues of difenoconazole were reportedly found in/on the rye forage sample and one of the two barley forage samples from the trials conducted in Germany (reported as 0.02 ppm and 0.03 ppm, respectively).  

Grain samples from the trials in France were analyzed with Method REM 07/86 (GC/ECD) with a reported "limit of sensitivity" of 0.02 ppm in/on grain; the original HED reviewer determined that the demonstrated limit of detection was 0.08 ppm in/on grain based an evaluation of the recovery data.  Grain samples from the trials in Germany were analyzed with a modified version of Method AG-537 (GC/ECD) or a modified version of Method AG-514, which is essentially identical to Method AG-537, with a reported "limit of sensitivity" of 0.02 or 0.03 ppm in/on grain; the original HED reviewer determined that the demonstrated LOQ was 0.05 ppm in/on grain. 

MRID 44602001  -  Data previously submitted and reviewed by HED under PP#2F4107
(DP#s 248285 and 248419, 10/28/98, S. Chun)

Wheat seed was treated with difenoconazole at 10.9 g ai/100 lb seed and planted at 15 sites (OK (2), TX (1), NC (1), MT (1), KS (2), CO (1), ND (1), SD (1), AR (1), ID (1), MO (1), MN (1), and NE (1)).  Wheat seed was treated with difenoconazole at 21.8 g ai/100 lb seed and planted at 3 sites (OK (1), KS (1), and (ND (1)).  Forage samples were collected 34-112 days after planting, additional forage samples were collected 164-241 days after planting (11 out of 15 trials), hay samples were collected 48-281 days after planting, and grain and straw samples were collected 83-322 days after planting.  Samples were analyzed with an acceptable data collection method (Method AG-575B (CG/NPD)); based on recovery data the demonstrated LOQ was 0.01 ppm for grain and 0.05 ppm for forage, hay, and straw.  No detectable residues of difenoconazole were found in/on any of the grain (<0.01 ppm), straw (<0.05 ppm), and hay (<0.05 ppm) samples.  Residues of difenoconazole were detectable in/on 4 of the 52 forage samples collected from the trials conducted at 10.9 g ai/100 lb seed; they ranged from <0.05 to 0.077 ppm.  No detectable residues of difenoconazole were found in/on the forage samples from the 3 trials conducted at 21.8 g ai/100 lb seed.  [Note:  The trials which found detectable residues of difenoconazole in/on forage were only conducted at the lower, 10.9 g ai/100 lb seed, treatment rate.]

Barley Field Trials

MRID 44056001  -  Data previously submitted and reviewed by HED under PP#6F4748
(DP# 228403, 9/23/96, G. Kramer)

Barley seed was treated with difenoconazole at 10.9 g ai/100 lb seed and planted at 9 sites (ID (1), ND (1), MN (1), MT (1), ND (1), SD (1), VA (1), CO (1), and CA (1)).  Barley seed was treated with difenoconazole at 21.8 g ai/100 lb seed and planted at 1 site (ND).  Forage samples were collected 32-152 days after planting; hay samples were collected 54-191 days after planting; and grain and straw samples were collected 89-224 days after planting.  Samples were analyzed with an acceptable data collection method (Method AG-575B (CG/NPD)); based on recovery data the demonstrated LOQ was 0.01 ppm for grain and 0.05 ppm for forage, hay, and straw.  No detectable residues of difenoconazole were found in/on any of the grain (<0.01 ppm), forage (<0.05 ppm), straw (<0.05 ppm), and hay (<0.05 ppm) samples.

Conclusions:  No oats and rye field trial data were submitted with the current petition (PP#0F7785).  Instead the petitioner has requested the translation of previously submitted wheat and barley field trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.  Given the deliberations by ChemSAC (meetings of 11/25/09 and 9/1/10) on this subject, the requested translations are deemed appropriate since the seed treatment uses under consideration are substantially similar to those reflected in the available wheat and barley field trial data and the resulting residues were either nondetectable (grain and hay), negligible (a few detectable residues in/on some straw samples below the LOQ of the current enforcement method for straw), or very low (a few detectable residues in/on some forage samples) in/on the raw agricultural commodities (RACs) of wheat and barley.  Hence, barley grain data may be translated to oat grain since barley and oat grains are kernels (caryopsis) plus hulls (lemma and palea); wheat grain data may be translated to rye grain since rye and wheat grains are kernels with hulls removed.  Wheat forage data may be translated to oat and rye forage.  Wheat straw data may be translated to oat and rye straw.  Wheat hay data may be translated to oat hay.

Taking into account the proposed maximum seed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley, rye, and wheat (both domestic (Dividend(R) Fungicide (EPA Reg. No. 100-740) and non-domestic (use information previously provided under PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola)), HED will need to evaluate the available data for the following maximum seed treatment use rates:  27.2 g ai/100 lb seed for the rye and wheat and 11 g ai/100 lb seed for barley and oats.  

Grains.  No detectable residues of difenoconazole were found in/on any of the wheat and barley grain samples collected from the supporting field trials.  Most of these data were collected with the current enforcement method, Method AG-575B (GC/NPD), or a substantially similar precursor (Method AG-575), having a LOQ of 0.01 ppm in/on grain.  However, a limited number of the older wheat grain data submitted with the first food use of difenoconazole (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola) from trials conducted in Europe (France (5 trials) and Germany (4 trials)) were generated with other, less sensitive data collection methods, precipitating the earlier recommendation to establish tolerances for residues of difenoconazole in/on barley grain, rye grain, and wheat grain at the higher current levels, 0.1 ppm.  These established tolerance levels are based primarily on wheat grain samples from trials conducted in France at the maximum seed treatment use rate for wheat (27.2 g ai/100 lb seed) in which residues in/on grain samples were reported as nondetectable, <0.02 ppm; below the reported "limit of sensitivity" of the data collection method (0.02 ppm in/on grain).  The original HED reviewer of these data (PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola) determined that the demonstrated limit of detection, 0.08 ppm in/on grain, was higher than the reported "limit of sensitivity" (0.02 ppm in/on grain) based on the recovery data; hence, a tolerance level of 0.1 ppm was established.  Having re-evaluation the chromatograms for the grain samples collected from the trials conducted in France and Germany, the reviewer finds that residues of difenoconazole in/on the treated grain samples were not greater than those in/on the associated untreated grain samples.  Hence, taking into account all of the available evidence, the reviewer finds that no detectable residues of difenoconazole (i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), are expected in/on the grains of barley, oats, rye, and wheat from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  

Hay and Straw.  Available wheat straw data were translated to oat and rye straw.  Available wheat hay data were translated to oat hay.  Available barley hay and straw data are considered supporting data.
 
Having re-evaluated the previously submitted wheat hay and straw data, the reviewer finds that residues of difenoconazole are not expected to exceed 0.05 ppm (the LOQ of the current enforcement method for hay and straw) in/on barley hay, barley straw, oat hay, oat straw, rye straw, wheat hay, and wheat straw from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.

Forage.  Available wheat forage data were translated to oat and rye forage.  Available barley forage data are considered supporting data.

Having re-evaluated the previously submitted wheat forage data, and using the OECD MRL calculator, the reviewer finds that the available data will support a tolerance of 0.15 ppm in/on rye, oat, and wheat forages.  The tolerance calculation is presented in Appendix I.  The wheat forage field trial data selected for inclusion in the OECD MRL calculation was a large dataset (24 field trials) reflecting the maximum proposed seed treatment use rate for oats and rye (11 g ai/100 lb seed), the same maximum use rate currently registered in the U.S. for barley, wheat, and triticale, and reflecting foraging/harvesting 34- to 61-days after planting treated seed.  Taken as a whole, the available wheat forage data indicate that residues of difenoconazole are not expected to exceed 0.15 ppm in/on rye, oat, and wheat forages from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  

Pregrazing and/or preharvest intervals are not needed for barley forage which is not considered a raw agricultural commodity (RAC) of barley. 

Pregrazing and/or preharvest intervals are not needed for oat, rye, and wheat forages given that the use pattern is limited to seed treatment and the supporting wheat forage data collected at 34- to 61-days after planting, which were used to set tolerances in/on oat, rye, and wheat forages, reasonably reflect the shortest period possible between planting and grazing/harvesting these forages.  [Note:  Agricultural practices information provided via personal communication with B. Schneider of HED.  Reference:  http://northerngraingrowers.org/wp-content/uploads/managing-small-grains-for-forage.pdf]  Furthermore, according to the Agency's most recent guidance on constructing reasonably balanced livestock diets (ChemSAC memo, 6/30/08), oat, rye, and wheat forages are fed to high-production dairy cattle only and the most recently constructed dairy cattle diet (PP# 9F7676; DP# 378829, 2/23/11, B. Cropp-Kohlligian) included wheat forage which contributed little (0.04 ppm) to the 1.6 ppm maximum dietary burden (MDB) for dairy cattle which was dominated by the contribution of wet apple pomace (1.13 ppm).  Hence, even a relatively significant increase in residues of difenoconazole in/on oat, rye, and wheat forages is expected to have no significant impact on the MDB for dairy cattle.


 



 860.1550 Proposed Tolerances

Tolerances for plant commodities are established under §180.475(a)(1), and are expressed in terms of difenoconazole per se.  The tolerances proposed by Syngenta are also expressed in terms of difenoconazole per se and are listed in Table 3 along with the tolerance levels recommended by HED and corrected commodity definitions.

No new residue chemistry data were submitted with the current petition.  Instead available barley and wheat magnitude of the residue data were translated to support the proposed uses on oats and rye.  These data were re-evaluated primarily for the purposes of harmonization and secondarily for the purposes of setting tolerances in accordance with current guidance.  See Table 3 for details.  Based on the available wheat processing data, tolerances in the processed commodities of barley, oats, rye, wheat, and triticale are not needed for the seed treatment uses under consideration. 

Codex maximum residue limits (MRLs) for residues of difenoconazole have been established.  Codex MRLs for residues of difenoconazole per se have been established at 0.02 ppm (absent at the limit of quantitation) for wheat grain and 3 ppm for wheat straw and fodder, dry; these levels are based on a foliar use of difenoconazole which is not registered in the U.S.  Since no Codex MRLs have been established for residues of difenoconazole in/on oat commodities, rye commodities, and wheat hay, harmonization with Codex is not an issue.  Canadian MRLs for residues of difenoconazole per se have been established at 0.01 ppm for barley grain; 0.01 ppm for oat grain; 0.01 ppm for rye grain; and 0.1 ppm for wheat grain.  Harmonization with the established Canadian MRLs of 0.01 ppm for residues of difenoconazole in/on oat grain and rye grain is recommended.  Mexican MRLs have been established for difenoconazole; however, no Mexican MRLs have been established for any cereal grains.  
 

Table 3. 	Tolerance Summary for Difenoconazole.
Commodity
                           Proposed Tolerance (ppm)
                             Recommended Tolerance
                                     (ppm)
Correct Commodity Definition;
Comments
Oats, grain
                                      0.1
                                     0.01
Oat, grain.  The proposed tolerance is too high.  Based on the translation and re-evaluation of available barley grain data, no detectable residues of difenoconazole per se are expected in/on oat grain from the maximum seed treatment use under consideration.  Therefore, the tolerance should be established at the limit of quantitation (LOQ) of the current enforcement method, 0.01 ppm in/on grain; a level consistent with the established Canadian MRL in/on the same commodity. 
Oats, forage
                                      0.1
                                     0.15
Oat, forage.  Based on the translation and re-evaluation of available wheat forage data, and using the OECD MRL calculator, a tolerance of 0.15 ppm is appropriate for the maximum seed treatment use under consideration. 
Oats, hay
                                      0.1
                                     0.05
Oat, hay.  Based on the translation and re-evaluation of available wheat hay data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on hay, for the maximum seed treatment use under consideration.
Oats, straw
                                      0.1
                                     0.05
Oat, straw.  Based on the translation and re-evaluation of available wheat straw data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on straw, for the maximum seed treatment use under consideration.
Rye, grain
                                      0.1
                                     0.01
Based on the translation and re-evaluation of available wheat grain data, no detectable residues of difenoconazole per se are expected in/on oat grain from the maximum seed treatment use under consideration.  Therefore, the tolerance should be established at the limit of quantitation (LOQ) of the current enforcement method, 0.01 ppm in/on grain; consistent with the established Canadian MRL in/on the same commodity.   Note:  The recommended tolerance for rye grain (0.01 ppm) should replace the existing import tolerance for rye grain (0.1 ppm).
Rye, forage
                                      0.1
                                     0.15
See comments above under Oat, forage.
Rye, straw
                                      0.1
                                     0.05
See comments above under Oat, straw.
Wheat, hay
                                      0.1
                                     0.05
Based on the re-evaluation of available wheat hay data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on hay, for the maximum seed treatment use under consideration.
      




References

DP#s:		172067 and 178394
Subject:	PP#2E4051.  CGA-169374 (Difenoconazole, Dividend(R)) in Imported Wheat, Barley, and Rye Grain.  First Food Use.  CBTS# 9029, 9895.
From:		R. Lascola
To:		J. Stone/C. Giles-Parker
Dated:		10/22/92
MRIDs:	42090001-42090004, 42090032-42090059, and 42303901


DP#:		228403
Subject:	PP#6F4748.  Difenoconazole (Dividend) in or on Barley, Oats, and Triticale.  Evaluation of Residue Data and Analytical Methods.  Case 287954.  Chemical 128847.  CBTS# 17407.
From:		G. Kramer
To:		C. Eiden/D. McCall
Dated:		9/23/96
MRIDs:	44056001


DP#s:	248285 and 248419
Subject:	PP#2F4107.  Difenoconazole (Dividend) in/on Wheat and Animal RACs.  Amendments of 7/8/98 and 7/30/98.  Chemical 128847.
From:	S. Chun
To:	C. Giles-Parker/J. Bazuin
Dated:	10/28/98
MRIDs:	44602001-44602001 and 44619401


DP#:		375159
Subject:	Difenoconazole.  Dissociation Constant in Water Data to Satisfy OPPTS 830.7370 Guideline Requirements.
From:		B. Cropp-Kohlligian
To:		Rosemary Kearns/Tony Kish
Dated:		5/26/10
MRID:		47957001


DP#:		378829
Subject:	Difenoconazole.  Application for Amended Section 3 Registration to Add Uses on Carrots, Chickpeas, Soybeans, Stone Fruits (Group 12), Strawberries, and Turnip Greens.  Summary of Analytical Chemistry and Residue Data.
From:		B. Cropp-Kohlligian
To:		Rosemary Kearns/Tony Kish
Dated:		2/23/11
MRIDs:	47929801-47929805

F.	DOCUMENT TRACKING

Petition Number:  0F7785 (oat commodities, rye commodities, and wheat hay)
DP Barcode(s): 384073
PC Code: 128847

Template Version September 2003
International Residue Limits 

                       Difenoconazole (128847; 3/21/11)
Summary of US and International Tolerances and Maximum Residue Limits 
Residue Definition:
US
Canada
Mexico[2]
Codex[3]
40 CFR 180.475:
Plant: difenoconazole, 1-[2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole

Livestock: difenoconazole, 1-[2-[2-chloro-4-(4-chlorophenoxy)phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole, and its metabolite, CGA-205375, 1-[2-chloro-4-(4-chloro-phenoxy)phenyl]-2-[1,2,4]triazol-1-yl-ethanol

1-[2-[4-(4-chlorophenoxy)-2-chlorophenyl]-4-methyl-1,3-dioxolan-2-ylmethyl]-1 H-1,2,4-triazole

Plant commodities: difenoconazole
Animal commodities:
sum of difenoconazole and 1-[2-chloro-4-(4-chloro-phenoxy)-phenyl]-2-(1,2,4-triazol)-1-yl-ethano), expressed as difenoconazole. The residue is fat soluble.
Commodity[1]
Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US
Canada
Mexico[2]
Codex
Oat, grain[3]
0.01
0.01


Oat, forage
0.15



Oat, hay
0.05



Oat, straw
0.05



Rye, grain[3]
0.01
0.01


Rye, forage
0.15



Rye, hay
0.05



Rye, straw
0.05



Wheat, hay
0.05



Completed:  M. Negussie; 03/28/2011
Subsequently Edited by B. Cropp-Kohlligian to Provide More Information With Additional Footnote 3
[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] Having re-evaluated the available barley and wheat field trial data which were translated to support the proposed seed treatment uses of difenoconazole on oats and rye, the reviewer finds that no detectable residues of difenoconazole (i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), are expected in/on the grains of barley, oats, rye, and wheat from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains.  Although difenoconazole is not currently registered in the U.S. for use on rye, an import tolerance is currently established under 40 CFR §180.475(a)(1) for residues of difenoconazole in/on rye grain at 0.1 ppm.  


Appendix I.  Tolerance Assessment Calculations.

For each of the crops listed below, the OECD MRL Calculator User Guide (SOP), along with the tolerance spreadsheet, was used for calculating recommended tolerances.  As specified in the SOP, the tolerance calculation is in the region of the 95[th] percentile of the underlying residue distribution, and is more likely to overestimate rather than underestimate the 95[th] percentile.  The rounding procedures specified in the SOP were also used.  The OECD tolerance spreadsheet does not require the use of maximum-likelihood estimation (MLE) procedures for values <LOQ.  

Wheat forage

The dataset used was large (24 samples) and consisted of field trial data representing seed treatment at a maximum seasonal application rate of 9.5-11 g ai/100 lb seed (consistent with the proposed domestic use rate) and reflecting 35-61 day PHIs.  Seventy-five percent of the data were censored.  Data reflecting longer PHIs were excluded from the calculation; they were all censored data.  [Note:  Exclusion of data reflecting longer PHIs had no effect on the tolerance estimate.]  The residue values that were entered into the OECD tolerance spreadsheet are provided in Table I-1.  Using the OECD spreadsheet (Figure I-1) the appropriate tolerance is 0.15 ppm in/on wheat forage and, by translation, oat and rye forages.

Table I-1.  Residue data used to calculate tolerance for difenoconazole in/on wheat forage.
                                   Trial No.
Trial Site
Trial ID
Region
                                      PHI
                                    (days)
                                Residues Found
                                     (ppm)
                Average Residues Used in OECD MRL Calculations
                                     (ppm)
MRID 42090055; Data previously reviewed by HED under PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola).
                                       1
ND
MW-FR-504-89
Region 5
                                      60
                              <0.01, <0.01
                                   <0.01
                                       2
MT
MW-FR-503-89
Region 7
                                      60
                              <0.01, <0.01
                                   <0.01
                                       3
MN
MW-FR-703-89
Region 5
                                      61
                              <0.01, <0.01
                                   <0.01
                                       4
SD
MW-FR-603-89
Region 5
                                      60
                                  0.02, 0.02
                                     0.02
                                       5
IL
04-FR-001-89
Region 5
                                      54
                              <0.01, <0.01
                                   <0.01
                                       6
NY
05-FR-004-89
Region 1
                                      60
                                0.02, <0.01
                                     0.015
                                       7
AR
0S-FR-208-89
Region 4
                                      61
                                <0.01, 0.02
                                     0.015
                                       8
TX
OS-FR-208-89
Region 6
                                      59
                              <0.01, <0.01
                                   <0.01
                                       9
AZ
OW-FR-504-89
Region 10
                                      56
                              <0.01, <0.01
                                   <0.01
                                      10
KS
MW-FR-304-89
Region 5
                                      61
                              <0.01, <0.01
                                   <0.01
MRID 44602001; Data previously reviewed by HED under PP#2F4107 (DP#s 248285 and 248419, 10/28/98, S. Chun).
                                      11
Caddo County, OK
OS-FR-101-95
Region 8
                                      45
                              <0.05, <0.05
                                   <0.05
                                      12
Wayne County, NC
OS-FR-601-95
Region 9
                                      42
                              <0.05, <0.05
                                   <0.05
                                      13
Yellowstone County, MT
OW-FR-201-95
Region 9
                                      52
                              <0.05, <0.05
                                   <0.05
                                      14
Pawnee County, KS
MW-FR-301-95
Region 8
                                      40
                              <0.05, <0.05
                                   <0.05
                                      15
Edwards County, KS
MW-FR-302-95
Region 8
                                      42
                              <0.05, <0.05
                                   <0.05
                                      16
Weld County, CO
MW-FR-303-95
Region 8
                                      42
                                 0.074, 0.062
                                     0.068
                                      17
Ward County, ND
MW-FR-501-95
Region 7
                                      35
                              <0.05, <0.05
                                   <0.05
                                      18
Corson County, SD
MW-FR-502-95
Region 7
                                      34
                              <0.05, <0.05
                                   <0.05
                                      19
Jackson County, AR
OS-FR-101-96
Region 4
                                      42
                                <0.05, 0.077
                                     0.064
                                      20
Caddo County, OK
OS-FR-750-96
Region 8
                                      42
                              <0.05, <0.05
                                   <0.05
                                      21
Latah County, ID
OW-FR-601-96
Region 9
                                      42
                              <0.05, <0.05
                                   <0.05
                                      22
Jackson County, MO
MW-FR-210-96
Region 5
                                      42
                                <0.05, 0.061
                                     0.056
                                      23
Traverse County, MN
MW-FR-503-96
Region 5
                                      36
                              <0.05, <0.05
                                   <0.05
                                      24
York County, NE
MW-FR-610-96
Region 5
                                      42
                              <0.05, <0.05
                                   <0.05


Figure I-1.  OECD tolerance spreadsheet summary of difenoconazole field trial data for wheat forage.
                                Difenoconazole
                                 Wheat Forage
                      Use Rate:  9.5-11 g ai/100 lb seed
                               PHI: 35-61 days
 
 
Total number of data (n)
                                      24
Percentage of censored data
                                      75%
Number of non-censored data
                                       6
Lowest residue
                                     0.010
Highest residue
                                     0.068
Median residue
                                     0.050
Mean
                                     0.036
Standard deviation (SD)
                                     0.021
Correction factor for censoring (CF)
                                     0.500
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.068
- Mean + 4 SD
                                     0.120
- CF x 3 Mean
                                     0.054
Unrounded MRL
                                     0.120
 
                                       
Rounded MRL
                                     0.15
 
                                       
 High uncertainty of MRL estimate.
[High level of censoring]



