Document ID: EPA-HQ-OPP-2006-0297-0005
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-09-19T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

						   OFFICE OF

								PREVENTION, PESTICIDES

								AND TOXIC SUBSTANCES

MEMORANDUM

	28 December 2006

	Subject:	Desmedipham.  Request for Tolerances on Spinach and Garden
Beet, Roots and Tops.  Summary of Analytical Chemistry and Residue Data.
 PP#6E7027.

DP Barcodes:	327443	Decision Number:	364160

PC Code:	104801	MRID Numbers:	46734101, 46734102

40 CFR 180.	353

Chemical Class:	Phenyl-carbamate

	From:	P. Yvonne Barnes

		Reregistration Branch 2

		Health Effects Division (7509P)

		

	Through:

		Alan Nielsen, Branch Senior Scientist

		Reregistration Branch 2

		Health Effects Division (7509P)

		

	To:	

		Daniel Rosenblatt

		Risk Manager

		Registration Division (7505P)

This document was originally prepared under contract by Dynamac
Corporation (1910 Sedwick Road, Building 100, Durham, NC 27713;
submitted 8/25/2006).  The document has been reviewed by the Health
Effects Division (HED) and revised to reflect current Office of
Pesticide Programs (OPP) policies.

Executive Summary

Desmedipham is a phenyl-carbamate herbicide (Group 5 herbicide)
currently used for the control of annual broadleaf weeds in sugar beets.
 Permanent tolerances are established for residues of desmedipham per se
at 0.2 ppm in/on sugar beet roots and tops [40 CFR §180.353], and
time-limited tolerances, set to expire 06/30/08, are established for
residues in/on garden beets at 0.2 ppm for roots and 15 ppm for tops.

Interregional Research Project No.4 (IR-4) has submitted a petition
supporting the use of desmedipham, formulated as a 1.3 lb/gal EC
(BETANEX® Herbicide; EPA Reg. No. 264-620), on garden beets and
spinach.  The proposed use on garden beets is for up to three broadcast
foliar applications using ground equipment at 0.24 to 0.49 lb
a.i./A/application from the cotyledon to 8-leaf stage, at retreatment
intervals (RTIs) of 5 to 7 days, for a total of 1.13 lb a.i./A/season;
no preharvest intervals (PHIs) are specified.  The proposed use on
spinach is for a single broadcast foliar application at up to 1.0 lb
a.i. /A from the 2-leaf stage up to 21 days before harvest.  In
conjunction with these uses, IR-4 is proposing permanent tolerances for
residues of desmedipham at 6.0 ppm in/on spinach, and at 1.0 ppm and
0.05 ppm in/on garden beet tops and roots, respectively.

The nature of the desmedipham residues in plants and animals is
adequately understood.  Based on an acceptable phenmedipham sugar beet
metabolism study, the Agency determined that phenmedipham and
desmedipham should be regulated in the same manner.  Therefore, the
residue of concern in plants is desmedipham per se.  Based on acceptable
poultry and ruminant metabolism studies reflecting oral dosing of
14C-desmedipham, the Agency also determined that desmedipham per se
should be the regulated residue in animal commodities. 

A LC/MS/MS method (Method AL/01/02) is available as a potential
tolerance enforcement method.  The method has a validated limit of
quantitation (LOQ) of 0.05 ppm for desmedipham in/on beet roots and
tops, and the method has undergone a successful independent laboratory
validation (ILV) trial.  However, this method must still undergo an
Agency method validation trial.  In the submitted spinach and table beet
field trials, residues of desmedipham were determined using an HPLC/UV
method (MTVL Method D23023), which was adequately validated in
conjunction with the analysis of the field trial samples.  The validated
LOQ for the HPLC/UV method is 0.05 ppm for desmedipham in/on spinach and
garden beet roots and tops.

In conjunction with the field trials, the petitioner provided adequate
storage stability data indicating that desmedipham is stable for up to
13 months in frozen spinach and for up to 9-10 month in frozen beet
roots and tops.  These data will support the current field trails, in
which spinach samples were stored frozen for up to 11.6 months and beet
root and tops samples were stored frozen for up to 9.6 months.

The available field trial data are adequate and support the proposed use
pattern.  The number and geographic distribution of the field trials are
adequate, and the appropriate samples were collected at the proposed
PHIs.  In six field trials conducted in growing zones 1, 5, 6 and 12
during 1996, desmedipham (1.3 lb/gal EC) was applied to garden beets as
three broadcast foliar applications from the cotyledon to 8-leaf stage
at RTIs of 5-17 days.  The first two applications were made at 0.24 to
0.25 lb a.i. /A (1x and 0.7x rates), and the last application was made
at 0.49-0.51 lb a.i. /A (1x rate), for totals of 0.99-1.01 lb a.i. /A
(0.9x seasonal rate).  All applications were made using ground equipment
and did not include the use of any adjuvants.  Residues of desmedipham
were <0.05 ppm -0.866 ppm in/on 10 samples of tops harvested at 14-15
days after the last treatment (DAT) and <0.05 ppm in/on 12 samples of
roots harvested at 49-52 DAT.  Average residues were 0.20 ppm for tops
and 0.025 ppm (½LOQ) for roots.  

In eight spinach field trials conducted in growing zones 1, 2, 6 and 10
during 1997-1999, desmedipham (1.3 lb/gal EC) was applied to spinach as
a single broadcast foliar application during crop development at
0.96-1.02 lb a.i./A.  All applications were made using ground equipment
and did not include the use of any adjuvants.  Residues in/on 12 samples
of spinach leaves harvested at 20-24 DAT were <0.05 ppm to 5.0 ppm. 
Residue data from one of the TX field trials were excluded from the data
base because apparent residues in control samples (0.098 ppm and 2.3
ppm) from this site indicated a problem with that test.

As there are no livestock feedstuffs associated with the proposed uses
on garden beets and spinach, the proposed uses will have no impact on
the potential transfer of residues to livestock and poultry commodities.

Although additional information is required to upgrade the existing
confined rotational crop study, the available data   SEQ CHAPTER \h \r 1
indicate that limited and/or extensive field rotational crop studies are
not required to support the proposed uses, and that rotational crop
restrictions are not necessary.

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

No major deficiencies were noted in the subject petition that would
preclude establishing permanent tolerances for desmedipham on garden
beets and spinach.  The deficiencies noted in this petition are listed
below.  Once the recommended label changes are made and the proposed
enforcement method is adequately validated by the Agency, HED  SEQ
CHAPTER \h \r 1  will recommend for establishing permanent tolerances
for the residues of desmedipham at 0.05 ppm and 1.0 ppm for garden beet
roots and tops, respectively, and at 6.0 ppm for spinach.  

•	The use directions for garden beets should be amended to specify
minimum PHIs of 14 days for tops and 50 days for roots.

•	The current tolerance enforcement method listed in PAM Vol. II for
desmedipham is not adequate.  However, an adequate LC/MS/MS method
(Method AL/01/02) is available that has undergone a successful ILV
trial.  This method will be forwarded to the Analytical Chemistry Branch
for a petition method validation trial.

•	Although data from the available   SEQ CHAPTER \h \r 1 confined
rotational crop study indicate that rotational crop restrictions are not
required for the proposed uses, the Desmedipham RED (08/95) noted that
sample storage information and supporting storage stability data are
required in order to upgrade the existing confined study to acceptable.

Background

Desmedipham is a phenyl-carbamate herbicide (Group 5 herbicide) used for
the control of annual broadleaf weeds in sugar beets.  The
Reregistration Eligibility Decision (RED) for desmedipham was issued on 
 SEQ CHAPTER \h \r 1  08/21/95, and the Tolerance Reassessment
Eligibility Decision (TRED) was issued on 01/25/05.  Desmedipham is
currently registered to Bayer CropScience and is marketed under the
trade names BETANEX®, BETAMIX®, and PROGRESS® Herbicides (EPA Reg.
Nos. 264-620, 264-621, and 264-623).  All three products are EC
formulations:  BETANEX is a 1.3 lb/gal EC containing only desmedipham,
BETAMIX is a multiple active ingredient EC formulation containing 0.65
lb/gal each of desmedipham and phenmedipham, and PROGRESS is a multiple
active ingredient EC formulation containing 0.6 lb/gal each of
desmedipham, phenmedipham, and ethofumesate.

Permanent tolerances are established for residues of desmedipham at 0.2
ppm in/on sugar beet roots and tops [40 CFR §180.353(a)].  Time-limited
tolerances are also established for residues of desmedipham in/on garden
beets at 0.2 ppm for roots and at 15 ppm for tops; these tolerances are
currently set to expire on 06/30/08 [40 CFR §180.353(b)].

IR-4 has submitted a petition (PP#6E7027) proposing the use of
desmedipham (EC) on garden beets and spinach.  In conjunction with these
uses, the petitioner has proposed the following permanent tolerances for
the combined residues of desmedipham:

Beet, garden, roots	0.05 ppm

Beet, garden, tops	1.0   ppm

Spinach	6.0   ppm

The nomenclature and physicochemical properties of desmedipham are
presented below in Tables 1 and 2.

TABLE 1.	Desmedipham Nomenclature.

Compound	

Common name	Desmedipham

Company experimental name	EP - 475; SN 38107

IUPAC name	ethyl 3-phenylcarbamoyloxycarbanilate

CAS name	ethyl [3-[[(phenylamino)carbonyl]oxy]phenyl]carbamate

CAS registry number	13684-56-5

End-use product (EP)	Betanex® 1.3EC Herbicide (1.3 lb/gal EC; EPA Reg.
No. 264-620)

TABLE 2.	Physicochemical Properties of the Technical Grade Desmedipham. 

Parameter	Value	Reference

Melting point/range	120 °C	Herbicide Handbook, 7th Ed. 1994

pH	Not Available

	Density	Not Available

	Water solubility (g/L) at 20 °C   	pH 7 -  0.07

	Solvent solubility (g/100mL) at 20 °C	Acetone ~ 40     	Methanol ~18
Toluene 0.12

Dibromoethane 1.78	Benzene ~ 0.16

	n-Hexane 0.05    	Chloroform ~ 8

Vapor pressure	3 x 10-9 mm Hg

	Dissociation constant, pKa	None

	Octanol/water partition coefficient, Log (KOW)	2455 at pH 3.9

	UV/visible absorption spectrum	Not Available

	

860.1200  Directions for Use

  SEQ CHAPTER \h \r 1 IR-4 is proposing the use of BETANEX® Herbicide
(EPA Reg. No. 264-260) on garden beets and spinach for the control of
selected broadleaf weeds.  BETANEX is a 1.3 lb/gal EC  formulation
currently registered for use on sugar beets at seasonal rates up to 1.95
a.i./A.  The petitioner provided both a summary of the proposed uses and
an example label from Bayer CropScience containing the use directions;
however, there were discrepancies between the summarized directions and
the example label.  The use directions summarized in Table 3 were taken
from the example label as they are more detailed and more closely
reflect the submitted field trial data.

Table 3.  Summary of Proposed Use Directions for Desmedipham.

Application Timing, Type, and Equipment 1	Formulation

[EPA

 Reg. No.]	Application. Rate

(lb a.i./A)	Max. No. Applications per Season	Max. Seasonal Application
Rate

(lb a.i./A)	PHI

(days)	Use Directions and Limitations

Garden Beets

Broadcast foliar applications from the cotyledon to 8-leaf stage using
ground equipment.	1.3 lb/gal EC

[264-620]

	0.24-0.49	3	1.13	Not specified	Maximum use rates are 0.24, 0.37, and
0.49 lb a.i./A/application at the 2-, 4-, and 6-leaf stages,
respectively.

Apply in a minimum of 10 gal/A for broadcast applications or 5 gal/A for
banded applications.

The specified RTI is 5-7 days.

	0.65 lb/gal EC

[264-621] 2	0.12-0.25

0.57	75

	Spinach

Single or split broad cast foliar application from 2-leaf stage up to 21
days prior to harvest using ground or aerial equipment.	1.3 lb/gal EC

[264-620]

	1.0	1	1.0	21	Apply in a minimum of 5 or 10 gal/A using aerial and
ground equipment.  The RTI for the split application is 4-6 days.

1   Applications through irrigation systems are prohibited.

2  This formulation is an MAI also containing 0.65 lb/gal of
phenmedipham (Sugar Beets).

     RTI = retreatment interval

Conclusions.  The proposed use directions adequately reflect the use
patterns used in the submitted garden beet and spinach field trials. 
Although the seasonal use rate for beets in the field trials (0.9x rate)
was slightly below the maximum proposed rate seasonal rate, the final
application in the garden beet field trials (0.5 lb a.i./A) was
equivalent to the proposed maximum for the third application (0.49 lb
a.i./A).  The label directions for garden beets should be amended to
include a minimum 14-day PHI for tops and a 50-day PHI for roots.

860.1300 Nature of the Residue - Plants

DP Barcode D216436, Desmedipham RED, D. Miller, 08/18/95

  SEQ CHAPTER \h \r 1 The qualitative nature of the residue in plants is
adequately understood.  The Agency has concluded that that the
metabolism of desmedipham in plants mirrors that of phenmedipham as the
two compounds are structurally similar (DP Barcode D213444, D. Miller,
03/24/95).  The sugar beet metabolism study conducted with phenmedipham
was considered adequate:  sugar beet leaves from plants grown in
nutrient solution were treated with radiolabeled phenmedipham by foliar
application or hypocotyl injection.  Phenmedipham and its
methyl-N-(3-hydroxy-phenyl)carbamate hydrolysis product (MHPC) in the
leaves comprised ~18% and 3% of the total applied radioactivity,
respectively.  In addition, conjugated O- and N-glucosides of the MHPC
metabolite and phenmedipham represented ~32% and 24% of the applied
activity, respectively.  

The Agency has concluded (DP Barcode D213531, D. Miller, 04/10/95) that
the sugar beet metabolism study on phenmedipham is adequate for
desmedipham and that phenmedipham and desmedipham should be regulated in
the same manner.  Therefore, the residue of concern for desmedipham is
desmedipham per se.

860.1300 Nature of the Residue - Livestock

DP Barcode D216436, Desmedipham RED, D. Miller, 08/18/95

DP Barcode D180687, Desmedipham, J. Abbotts, 08/26/92

DP Barcode D190920, Desmedipham, F. Fort, 01/28/94

  SEQ CHAPTER \h \r 1 The nature of the residues in animals is
adequately understood based on acceptable poultry and ruminant
metabolism studies reflecting oral dosing of 14C-desmedipham. The Agency
(DP Barcode D213531, D. Miller, 04/10/95) has determined that the
residue to be regulated in animals is desmedipham per se.

In the ruminant metabolism study, a lactating cow was dosed orally for 4
consecutive days with [14C] desmedipham uniformly labeled in the phenyl
ring with two substitutes at a rate equivalent to 10 ppm in the diet. 
Based on residues in sugar beet tops, this dosing level is equivalent to
~1x the maximum expected dietary burden.  After 4 days, total
radioactive residues (TRR) were 0.307 ppm in kidney, 0.040 ppm in liver,
≤0.01-0.024 ppm in fat, and ≤0.01 ppm in muscle.  Residues in milk
plateaued at ≤0.187 ppm after 3 days.  Identified residues comprised
85.8% of the TRR in kidney, 76.4% of the TRR in milk, and 25.5% of the
TRR in liver.  In kidney and milk, identified residues were
ethyl-N-3-hydroxyphenyl carbamate (EHPC) (76.7% TRR, 0.24 ppm in kidney
and 75.1% TRR, 0.14 ppm in milk) and 3-acetamidophenol (9.1% TRR, 0.03
ppm in kidney and 1.3% TRR, <0.01 ppm in milk).  In liver, the principal
residues were EHPC (13.5% TRR, <0.01 ppm) and 3-aminophenol (12.0% TRR,
<0.01 ppm).  In omental and perirenal fat, extracted residues were <0.01
ppm and included EHPC, desmedipham, 3-acetamidophenol, and
3-aminophenol.

In the poultry metabolism study, laying hens were dosed orally for 10
consecutive days at a dose of 1.5 mg/hen/day.  Radioactive residues in
excreta accounted for approximately 85.3% - 96.6% of the administered
dose.  During the dosing period, TRRs were 0.001 ppm - 0.017 ppm in egg
whites.  The TRR in a pooled egg yolk sample collected on Day 10 was
0.046 ppm.  Identified residues in yolks were 3-aminophenol (46.5% TRR,
0.022 ppm) and EHPC (26.5% TRR, 0.012 ppm) and with trace amounts of
3-acetamidophenol and desmedipham.  All other tissues contained TRR
values of less than 0.01 ppm.

860.1340 Residue Analytical Methods

46734101.der, D. Wilbur, 12/28/06

46734102.der, P. Y. Barnes, 12/28/06

45942201.der, S. Kinard, 07/08/04

The Agency previously determined that the existing GC/ECD method for
determining total residues of desmedipham in sugar beets (Method I in  
SEQ CHAPTER \h \r 1 PAM Vol. II, Section 180.353) is not adequate for
tolerance enforcement, as naturally-occurring anilines may interfere
with the analysis.  However, an adequate HPLC/UV detection method (MVTL
Method D23023) was available, which had undergone a successful ILV
trial.  For this method, residues in/on beets are extracted by refluxing
in acidified ethyl acetate.  Residues of desmedipham are then filtered,
concentrated and cleaned up using Florisil and C18 column eluted with
methanol : methylene chloride (5:95, v:v). The residues were rotary
evaporated to dryness, reconstituted in acetonitrile (65:35, v: v),
acidified with 2N H3P04 and filtered (0.45 µm). The final extract was
analyzed by HPLC using a C18 column with UV detection (235 nm).  The
validated LOQ for desmedipham is 0.05 ppm in/on roots and tops.

The Agency concluded that this HPLC/UV method could be adequate for
tolerance enforcement provided that the registrant submit additional
supporting raw data for the method and conduct an interference study
using propham and phenmedipham.  After submission of the requested data,
the Agency would then conduct a method validation trial.

Since the review of the above HPLC/UV method, Bayer has submitted a
method description and validation data for a LC/MS/MS method (Method
AL/01/02) for determining residues of desmedipham in/on sugar beet tops
and roots.  For this method, residues are extracted from roots and tops
by refluxing in ethyl acetate and methanol.  Residues are then filtered,
concentrated, redissolved in acidified acetonitrile/water (1:1, v:v),
and analyzed by HPLC using a MS/MS detector.  Adequate method recoveries
were obtained using samples of tops and roots fortified with desmedipham
at 0.05-2.5 ppm, and the method was also successfully validated in an
ILV trial using sugar beet tops fortified at 0.05-1.0 ppm.  The
validated LOQ is 0.05 ppm and the reported LOD is 0.008 ppm for roots
and 0.02 ppm for tops.  As the this method is more specific then the
earlier HPLC/UV method and does not require the use of a confirmatory
method or conducting an interference study, the LC/MS/MS method (Method
Al/01/02) should be forwarded to the Analytical Chemistry Branch for a
petition method validation trial.

An enforcement analytical method for desmedipham residues in animal
commodities are not needed because tolerances for animal commodities are
not required.

In the submitted spinach and table beet field trials, residues of
desmedipham were determined using an adequate HPLC/UV method (Method
D23023), which is an adaptation of the above HPLC/UV method.  For this
method, residues were extracted with acetone:water (60:40, v:v),
filtered, and partitioned into hexane.  Residues were dried over
anhydrous sodium sulfate, evaporated to dryness, re-dissolved in
methylene chloride and hexane, and then cleaned up using a Florisil
column eluted with 5% methanol in 95% methylene chloride.  Residues were
evaporated to dryness, reconstituted in acetonitrile:water (65:35, v:v),
acidified with 2N H3PO4, and filtered.  Residues were then analyzed by
HPLC/UV (235 nm), using external standards.  The validated LOQ is 0.05
ppm for residues of desmedipham in/on spinach and garden beet roots and
tops.  The above method was validated in conjunction with the analysis
of field trial samples and is adequate for data collection.

860.1360 Multiresidue Methods

  SEQ CHAPTER \h \r 1 The FDA multi-residue method testing data have
been forwarded to FDA for evaluation (memo to L. Sawyer from D.
McNeilly, dated 04/14/92).  The FDA PESTDATA database dated 10/99 (PAM
Vol. I, Appendix I) does not report recoveries for desmedipham using any
of the multiresidue methods in PAM Vol. I.

860.1380 Storage Stability

e at ≤-6ºC, and analyzed along with freshly fortified samples after
299 days (tops) or 263 days (roots) of storage.  The average corrected
recovery of desmedipham following frozen storage was 95% from tops after
9.8 months and 89% from roots after 8.6 months.  In the spinach field
trial, control samples of leaves were fortified with desmedipham at 5.0
ppm, placed in storage at -21ºC, and analyzed along with freshly
fortified samples after 405 days of storage.  The average corrected
recovery of desmedipham was 99% from spinach after 13.3 months of
storage.  In addition, the registrant reported that storage stability
data are available supporting the stability of desmedipham in frozen
sugar beet roots and tops for up to 24 months; however, these data have
not yet been submitted to the Agency for review.   The storage intervals
and conditions of samples from the garden beet and spinach field trials
are presented in Table 4.

≤-6	216-293	299

Table Beet Roots

 75-258	263

Spinach, Leaves	-21	  8-356	405

Conclusions.  The available storage stability data indicate that
desmedipham is stable in frozen spinach for at least 13 months and in
frozen beet root and tops for at least 9 to10 months.  These data
adequately support the sample storage intervals and conditions from the
field trials.

 

860.1400 Water, Fish, and Irrigated Crops

As no aquatic uses are being proposed, this guideline requirement is not
relevant to the current petition. 

860.1460 Food Handling

As no food handling uses are being proposed, this guideline requirement
is not relevant to the current petition. 

860.1480 Meat, Milk, Poultry, and Eggs

There are no livestock feedstuffs associated with the proposed uses on
garden beets and spinach. Therefore, data requirements pertaining to
meat, milk, poultry, and eggs are not relevant to this tolerance
petition.

860.1500 Crop Field Trials

46734101.der [Garden(Table) beets]

46734102.der (Spinach)

IR-4 has submitted field trial data supporting the use of desmedipham
(EC) on garden beets and spinach.  The results from these field trials
are discussed below and summarized in Table 5.

Table 5.	Summary of Residue Data from Crop Field Trials with Desmedipham
(EC).

Crop matrix	Total Applic. Rate  (lb a.i./A)	PHI (days)	Residue Levels
(ppm) 1

	n	Min.	Max.	HAFT 2	Median	Mean	Std. Dev.

Garden Beets

Tops	0.99-1.01	14-15	10	<0.05	  0.866	0.77	0.053	0.195	0.310

Roots

49-52	12	<0.05	<0.05	<0.05	 0.025	0.025	Not Applicable

Spinach

Spinach, leaves	0.96-1.02	20-24	13	<0.05	2.3	2.05	0.18	0.51	0.72

1The method LLMV is 0.05 ppm.  For calculation of the median, mean and
standard deviation, ½LLMV (0.025 ppm) was used for samples with
residues <LLMV.

2HAFT = Highest Average Field Trial.

	

Garden Beets.   In six field trials conducted in growing zones 1, 5, 6
and 12 during 1996, desmedipham (1.3 lb/gal EC) was applied to garden
beets as three broadcast foliar applications from the cotyledon to
8-leaf stage at RTIs of 5-17 days.  The first two applications were made
at 0.24-0.25 lb a.i. /A (1x and 0.7x rates), and the last application
was made at 0.49-0.51 lb a.i. /A (1x rate), for totals of 0.99-1.01 lb
a.i. /A (0.9x seasonal rate).  All applications were made using ground
equipment and did not include the use of any adjuvants.  Duplicate
control and treated samples of tops and roots were collected at
commercial maturity, 14-15 days DAT for tops and 49-52 DAT for roots. 
Maximum frozen storage intervals prior to analysis were 293 days for
tops and 258 days for roots; these intervals are supported by the
available storage stability data.  Samples of roots and tops were
analyzed for residues of desmedipham using an adequate HPLC/UV method
(MVTL Method No. D23023).  The validated LOQ is 0.05 ppm, and the LOD
was not reported.

Following the last of three broadcast applications totaling 0.99-1.01 lb
a.i. /A (0.9x rate), residues of desmedipham were <0.05-0.866 ppm in/on
10 samples of tops harvested at 14-15 DAT and <0.05 ppm in/on 12 samples
of roots harvested at 49-52 DAT.  Average residues were 0.20 ppm for
tops and 0.025 ppm (½LOQ) for roots, and the HAFT residues were 0.77
ppm for tops and <0.05 ppm for roots.

Spinach.  In eight spinach field trials conducted in growing zones 1, 2,
6 and 10 during 1997-1999, desmedipham (1.3 lb/gal EC) was applied to
spinach as a single broadcast foliar application during crop development
at 0.96-1.02 lb a.i./A.  All applications were made using ground
equipment and did not include the use of any adjuvants.  Duplicate
control and treated samples of spinach leaves were collected at
commercial maturity, 20-24 DAT, and samples were stored frozen up to 356
days prior to analysis, an interval supported by the available storage
stability data.  Samples of spinach were analyzed for desmedipham using
an HPLC/UV method (Method D23023).  The LLMV was 0.05 ppm, and the
calculated LOQ and LOD were 0.022 and 0.0074 ppm, respectively.

Following a single broadcast application of desmedipham (EC) at
0.96-1.02 lb a.i./A (1x rate), residues in/on 13 samples of spinach
leaves harvested at 20-24 DAT were <0.05-2.3 ppm. The HAFT residues were
2.05 ppm.  Residue data from one of the TX field trials were excluded
from the data base because apparent residues in control samples (0.098
and 2.3 ppm) from this site indicated a problem with that test.

Conclusions.  The available garden beet and spinach field trial studies
are adequate and reflect the proposed use patterns.  The field trial
data are supported by available storage stability data, and the residue
of concern, desmedipham, was determined using an adequate HPLC/UV
method.

860.1520 Processed Food and Feed

As there are no separately regulated processed commodities associated
with garden beets and spinach, this guideline requirement is not
relevant to the current petition. 

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

As of 07/2006, an analytical reference standard for desmedipham is
available at the EPA National Pesticide Standards Repository.

860.1850 Confined Accumulation in Rotational Crops

DP Barcode D216436, Desmedipham RED, D. Miller, 08/18/95

  SEQ CHAPTER \h \r 1 The nature of the residues in rotational crops is
adequately understood.  The available confined rotational crop study is
adequate, provided the dates of sample extraction and analysis for each
crop matrix as well as supporting storage stability data reflecting the
storage intervals and conditions of samples from the study are
submitted.  The existing study used an application rate of 2.2 lb a.i.
/A, which is ~2x the proposed rate for garden beets and spinach.

Limited and/or extensive field rotational crop studies are not required
because residues of the regulated parent were predominately <0.01 ppm
in/on rotational crop commodities from the 30-day plant-back interval. 
Therefore, rotational crop restrictions are not necessary and no
plant-back intervals need be prescribed.

860.1550 Proposed Tolerances

The Agency has determined that the regulated residue for desmedipham in
plant and animal commodities is desmedipham per se.  Permanent
tolerances are established for residues of desmedipham at 0.2 ppm in/on
sugar beet roots and tops [40 CFR §180.353(a)].  Time-limited
tolerances are also established for residues of desmedipham in/on garden
beets at 0.2 ppm for roots and at 15 ppm for tops; these tolerances are
currently set to expire on 06/30/08 [40 CFR §180.353(b)].    SEQ
CHAPTER \h \r 1 The proposed tolerances for garden beets and spinach are
listed in Table 6, along with the Agency’s recommended tolerance
levels. 

As a substantial fraction (>20%) of the samples for garden beet tops and
roots and spinach had residues <LOQ, the recommended tolerance levels
were not determined using the Agency’s Tolerance Setting Spreadsheet. 
Rather, tolerance levels were based on rounding up from the maximum
residue values.

There are no established or proposed Codex, Canadian or Mexican MRLs for
desmedipham (see International Residue Limit Status Sheet, attached). 
Therefore, no compatibility questions exist with respect to the proposed
U.S. tolerances.

Table 6. 	Tolerance Summary for Desmedipham.

Commodity	Proposed Tolerance (ppm)	Recommended Tolerance (ppm)	Comments:
Commodity Definition

Beet, garden, tops	1.0	1.0	Adequate field trial data are available. 
Residues were <0.05 ppm in/on 12 root samples and <0.05 ppm - 0.87 ppm
in/on 10 tops samples from beets treated at a 0.9x rate.

Beet, garden, roots	 0.05	 0.05

	Spinach	6.0	6.0	Adequate field trial data are available.  Residues were
<0.05 ppm -5.0 ppm in/on 13 samples of spinach treated at 1x rate.

RDI: P. Yvonne Barnes (11/07/2006), Don Wilbur (11/16/2006).

References

  SEQ CHAPTER \h \r 1 DP Barcode:	D213444	

Subject:	Desmedipham/Phenmedipham. Metabolism Committee Decision Re:
Regulation of Metabolites.  SEQ CHAPTER \h \r 1 

From:		D. Miller 

To:		Metabolism Committee

Dated:		03/24/95

MRID(s):	None

  SEQ CHAPTER \h \r 1 DP Barcode:	D213531	

Subject:	Desmedipham.  Outcome of 03/27/95 Meeting of HED Metabolism
Committee.  SEQ CHAPTER \h \r 1 

From:		D. Miller

To:		HED Metabolism Committee

Dated:		04/10/95

MRID(s):	None

  SEQ CHAPTER \h \r 1 DP Barcode:	D216436

Subject:	Desmedipham. (104801) Product and Residue Chemistry Chapters
for the Reregistration Eligibility Decision (RED).  SEQ CHAPTER \h \r 1 

From:		D. Miller

To:		R. Gebken and A. Aikens

Dated:		08/18/95

MRID(s):	None

  SEQ CHAPTER \h \r 1 Attachments:  

International Residue Limit Status sheet

Template Version September 2005



INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name:  ethyl [3-[[(phenylamino)carbonyl] oxy]phenyl]carbamate
Common Name:  Desmedipham

	X Proposed tolerance

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ࠀ Reevaluated tolerance

 Other	Date:  11/28/2006

Codex Status (Maximum Residue Limits)	Proposed U. S. Tolerances

X No Codex proposal step 6 or above

 No Codex proposal step 6 or above for the crops requested	Petition
Number:  PP#6E7027

DP Barcodes:   D327443

Residue definition (step 8/CXL):  	Reviewer/Branch: P. Yvonne Barnes,
RRB2

	Residue definition:  Desmedipham

Crop (s)	MRL (mg/kg)	Crop(s) 	Tolerance (ppm)

Spinach	6.0

Beet, garden, tops	1.0

Beet, garden, roots	0.05

Limits for Canada	Limits for Mexico

X No Limits

 No Limits for the crops requested	X  No Limits

  No Limits for the crops requested

Residue definition:	Residue definition:

Crop(s)	MRL (mg/kg)	Crop(s)	MRL (mg/kg)

Rev. 1998

Desmedipham	Summary of Analytical Chemistry and Residue Data	Barcode: 
D327443

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