Document ID: EPA-HQ-OPP-2007-0674-0014
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-02-06T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

	                 OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

	28 December 2006

	Subject:	Desmedipham.  Registrant’s Response to Desmedipham Tolerance
Reassessment Eligibility Decision (TRED).  Submission of Additional
Sugar Beet Field Trials.

DP Barcodes:	327740	Decision Number:	364160

PC Code:	104801	MRID No.:	46773001

42516500

40 CFR 180.	353

Chemical Class:	Phenyl-carbamate

	From:	P. Yvonne Barnes, Chemist

		Reregistration Branch 2

		Health Effects Division (7509P)

	Through:	Alan Nielsen, Branch Senior Scientist

		Reregistration Branch 2

		Health Effects Division (7509P)

				

	To:	

		Nathan Mottl, CRM

		Reregistration Branch 1

		Special Review and

		Reregistration Division (7508P)

This document was originally prepared under contract by Dynamac
Corporation (1910 Sedwick Road, Building 100, Durham, NC 27713;
submitted 08/25/2006).  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 [40 CFR
§180.353]  per se at 0.2 ppm in/on sugar beet roots and at 15 ppm in/on
sugar beet tops, and time-limited tolerances, set to expire 06/30/08.

  SEQ CHAPTER \h \r 1 Desmedipham is currently registered to Bayer
CropScience for use on sugar beets and is marketed under the trade names
Betanex®, Betamix®, and Progress® Herbicides.  All three products are
EC formulations; Bayer has canceled its registrations for wettable
powder (WP) formulations.  Betanex® is a 1.3 lb/gal EC, and Betamix®
and Progress® are multiple active ingredient (MAI) formulations
containing 0.6 to 0.65 lb/gal of desmedipham.  The current use on sugar
beets allows for multiple foliar applications totaling up to 1.95 lb
ai/A/season, with a minimum retreatment interval (RTI) of 5 days and a
preharvest interval (PHI) of 75 days.

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. 

The 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.  Samples from the available sugar beet
field trials were analyzed using either the above LC/MS/MS method or an
adequate HPLC/UV method (Method D23023), which was validated in
conjunction with the analysis of the field trial samples.  The LOQ for
the HPLC/UV method is 0.05 ppm for desmedipham in/on sugar beet roots
and tops.

Adequate data are available supporting the stability of desmedipham in
frozen sugar beet roots and tops for up to 8 months; however, samples
from the most recent field trials were stored for up to 14 months. 
Bayer has cited data indicating that desmedipham residues are stable for
up to 24 months in frozen roots and tops, but these data have not yet
been submitted.  The 24-month month storage stability study should be
submitted to the Agency for review.

If acceptable storage stability data are provided, the available sugar
beet field trial data are adequate and will support the current use
patterns.  The number and geographic distribution of the field trials
are adequate, and the appropriate samples were collected at the
specified PHI.  In the five field trials referenced in MRID 42516500
dated 1992 and the nine field trials conducted in 2004, desmedipham (1.3
lb/gal EC) was applied to sugar beets as two broadcast foliar
applications at 0.95 to 1.09 lb ai/A/application, at RTIs of 5 to 7
days, for a total of 1.93 to 2.09 lb ai/A (1x rate).  The initial
application was made from the 6-leaf stage to full crop cover (BBCH
stages 16 to 39), and all applications were made using ground equipment,
without the use of any adjuvant.  In the trials referenced in MRID
42516500, single control and treated samples of tops were collected from
each of the 5 trials at 75 days after the last application (DAT), and in
the 2004 studies, single control and duplicate treated samples of tops
and roots were collected at 71 to 75 DAT.  In the trials referenced in
MRID 42516500, residues of desmedipham in/on sugar beet tops were <0.05
ppm to 6.54 ppm.  In the 2004 trials, residues of desmedipham in/on
sugar beets were <0.05 ppm for the 18 root samples and <0.05 ppm to
0.135 ppm for the 18 tops samples, with only 5 of the 18 samples of tops
having residues >LOQ.  Average residues were 0.025 ppm for roots and
0.045 ppm for tops from the 2004 trials.

Using   SEQ CHAPTER \h \r 1 the reassessed tolerance of 5 ppm for sugar
beet tops, the maximum theoretical dietary burden of desmedipham for
beef and dairy cattle are 4.3 ppm and 2.2 ppm, respectively.  Based upon
the data from the available ruminant metabolism study, in which goats
were dosed at 10 ppm (1.1x), the Agency has concluded that infinite
residues of desmedipham are unlikely to occur in milk, meat and
meat-byproducts of ruminants. Therefore, a cattle feeding study and
tolerances for livestock commodities are not required. In addition, no
tolerances are necessary for hog or poultry commodities as sugar beet
commodities are not utilized in swine or poultry diets.

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 existing uses on sugar beets, and that
rotational crop restrictions are not necessary.

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

Provided that adequate storage stability data are submitted, the
requirements for desmedipham residue data on sugar beets are fulfilled
and tolerances can be reassessed.  However, in addition to the required
storage stability data, the following minor deficiencies still require
resolution.

    

•	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 should be forwarded to the Analytical Chemistry
Branch for a method validation trial.

•	Storage stability data are required to support frozen storage
intervals of up to 14 months for sugar beet roots and tops.  The
registrant should submit the existing 24-month storage stability study
for review.

•	Although data from the available   SEQ CHAPTER \h \r 1 confined
rotational crop study indicate that rotational crop restrictions are not
required, 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.

Based on the available residue data, HED recommends reassessing
tolerances for residues of desmedipham in/on sugar beet roots and tops
to 0.1 ppm and 5 ppm, respectively.  

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.  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 red
(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)].

Bayer CropScience, the basic producer of desmedipham, has submitted
additional field trial data on sugar beets in response to deficiencies
noted in the Desmedipham TRED.  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	AE B038107

IUPAC name	ethyl 3-phenylcarbamoyloxycarbanilate

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

CAS registry number	13684-56-5

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

Betamix® Herbicide (0.65 lb/gal EC; EPA Reg. No. 264-621)

Progress® Herbicide (0.6 lb/gal EC; EPA Reg. No. 264-632)

TABLE 2.	Physicochemical Properties of the Technical Grade Desmedipham. 

Parameter	Value	Reference

Melting point/range	118-119 ° C	Provided in MRID 46773001

pH	Not soluble in water

	Density	1.320 g/ml

	Water solubility (g/L) at RT	pH 7 -  0.007

pH 9 -  0.0134

pH 11 - 0.00442

	Solvent solubility (g/L) at RT	Acetone 285

Methanol 187

Ethyl Acetate 181

Methylene Chloride 19.9

Toluene 1.2

Hexane 0.02

	Vapor pressure	<-1.5 Torr (25 ° C)

	Dissociation constant, pKa	Does not dissociate in water

	Octanol/water partition coefficient, Log (KOW)	187

	UV/visible absorption spectrum	Primary     273nm

Secondary 203 nm

Tertiary     236 nm

	

860.1200 Directions for Use

  SEQ CHAPTER \h \r 1 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 264-632).
 All three products are EC formulations:  BETANEX® is a 1.3 lb/gal EC
containing only desmedipham; BETAMIX® is a multiple active ingredient
(MAI) formulation containing 0.65 lb/gal each of desmedipham and
phenmedipham; and PROGRESS® is also a MAI formulation containing 0.6
lb/gal each of desmedipham, phenmedipham, and ethofumesate.  Bayer is no
longer supporting the use of wettable powder (WP) formulations of
desmedipham.  The current use directions for sugar beets are summarized
in Table 3.

Table 3.  Summary of Existing Use Directions for Desmedipham on Sugar
Beets.

Applic. Timing, Type, and Equipment 1	Formulation

[EPA Reg. No.]	Application. Rate 

(lb ai/A)	Max. No. Applic. per Season	Max. Seasonal Rate

(lb ai/A)	PHI

(days)	Use Directions and Limitations 2

Conventional broadcast foliar applications beginning at cotyledon stage
using ground or aerial equipment.	1.3 lb/gal EC

[264-620]

	0.73-1.20

+

0.73-0.98	2	1.95	75	Do not exceed 0.24 lb ai/A when beets are at
cotyledon stage.

Apply in a minimum of 5 or 20 gal/A for aerial and ground applications.
The use of spray adjuvants is prohibited. The specified RTI 7 days.

Multiple low rate broadcast foliar applications beginning at cotyledon
stage using ground or aerial equipment

0.24-0.73	NS

	Use pattern not allowed in CA.  Do not exceed 0.24 lb ai/A when beets
are at cotyledon stage.  Apply in a minimum of 5 or 10 gal/A for aerial
and ground applications. The use of spray adjuvants is prohibited.  The
specified RTI 5 days.

Multiple “micro” rate broadcast foliar applications beginning at
cotyledon stage using ground or aerial equipment

0.08-0.12	3+

	Use pattern not allowed in CA.  Do not exceed 0.08 lb ai/A, prior to
4-leaf stage.  Apply in a minimum of 5 or 10 gal/A for aerial and ground
applications.  Applications may include the use of modified seed oil at
1.5% spray volume.  The specified RTI 5 days.

Conventional broadcast foliar applications beginning at cotyledon stage
using ground or aerial equipment.	0.65 lb/gal EC 3

[264-621]

	0.36-0.61

+

0.36-0.49	2	0.98	75	Do not exceed 0.12 lb ai/A when beets are at
cotyledon stage.  Apply in a minimum of 5 or 20 gal/A for aerial and
ground applications.  The use of spray adjuvants is prohibited.  The
specified RTI 7 days.

Multiple low rate broadcast foliar applications beginning at cotyledon
stage using ground or aerial equipment

0.24-0.36	NS

	Use pattern not allowed in CA.  Do not exceed 0.12 lb ai/A when beets
are at cotyledon stage.  Apply in a minimum of 5 or 10 gal/A for aerial
and ground applications.  The use of spray adjuvants is prohibited.  The
specified RTI 5 days.

Multiple “micro” rate broadcast foliar applications beginning at
cotyledon stage using ground or aerial equipment

0.08-0.12	3+

	Use pattern not allowed in CA.  Do not exceed 0.08 lb ai/A, prior to
4-leaf stage. Apply in a minimum of 5 or 10 gal/A for aerial and ground
applications. Applications may include the use of modified seed oil at
1.5% spray volume.  The specified RTI 5 days.

Conventional broadcast foliar applications beginning at cotyledon stage
using ground or aerial equipment.	0.6 lb/gal EC 4

[264-632]

	0.24-0.38

+

0.24-0.38	2	0.65	75	Do not exceed 0.11 lb ai/A when beets are at
cotyledon stage.  Apply in a minimum of 5 or 20 gal/A for aerial and
ground applications.  The use of spray adjuvants is prohibited.  The
specified RTI 7 days.

Multiple low rate broadcast foliar applications beginning at cotyledon
stage using ground or aerial equipment

0.11-0.24	NS

	Use pattern not allowed in CA

Do not exceed 0.24 lb ai/A when beets are at cotyledon stage.

Apply in a minimum of 5 or 10 gal/A for aerial and ground applications. 
The use of spray adjuvants is prohibited.  The specified RTI 5 days.

Multiple “micro” rate broadcast foliar applications beginning at
cotyledon stage using ground or aerial equipment

0.08-0.12	3+

	Use pattern not allowed in CA.  Do not exceed 0.08 lb ai/A, prior to
4-leaf stage.  Apply in a minimum of 5 or 10 gal/A for aerial and ground
applications.  Application may include the use of modified seed oil at
1.5% spray volume.  The specified RTI 5 days.

1              Applications through irrigation systems are prohibited.

2	All three labels prohibit rotation to cereal grain crops for 120 days
following postemergence application.

3	This formulation is a MAI also containing 0.65 lb/gal of phenmedipham.

4	This formulation is a MAI also containing 0.6 lb/gal each of
phenmedipham and ethofumesate.

RTI = retreatment interval.

NS = not specified.

	

Conclusion:  The current use directions on all three labels are similar,
with the two MAI formulations having proportionally lower use rates than
the 1.3 lb/gal EC.  The use directions are for sugar beets are supported
by the available field trial data.

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 based on an acceptable sugar beet metabolism study
using phenmedipham.  The Agency has concluded that that the metabolism
of desmedipham in plants mirrors that of phenmedipham, as the two
compounds are structurally similar, and that the two compounds should be
regulated in the same manner.  Therefore, the residue of concern for
desmedipham in plants is desmedipham per se.

860.1300 Nature of the Residue – Livestock

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

  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.

≤0.01 ppm to 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% to 96.6 % of the administered
dose.  During the dosing period, TRRs were 0.001 ppm to 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

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

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
(Desmedipham Method R75) 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 columns. 
Purified residues are redissolved in acetonitrile:water (1:1, v:v),
acidified, and 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, and the reported LOD is 0.004 ppm.

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.

MS/MS, using a Hypersil column with a gradient of 0.1% acetic acid to
acetonitrile, and residues were quantified using the 301→182 m/z
transition.  Adequate method recoveries were obtained using samples of
tops and roots fortified with desmedipham at 0.05 ppm to 2.5 ppm, and
the method was also successfully validated in an ILV trial using sugar
beet tops fortified at 0.05 ppm to 1.0 ppm.  The validated LOQ is 0.05
ppm and the reported LOD is 0.008 ppm for roots and 0.023 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.

Samples from the sugar beet field trials were analyzed using adequate
data collection methods.  Samples of tops from the sugar beet field
trials referenced in MRID 42516500/01 dated 1992 were analyzed using the
HPLC/UV method (Desmedipham Method/R75) and samples of roots and tops
from the more recent field trials (2001-2004) were analyzed using the
above LC/MS/MS method (Method AL/01/02). 

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

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

The Desmedipham RED (08/95) noted that data are available supporting the
stability of desmedipham in frozen (-21ºC) sugar beet roots and tops
for up to 8 months.  These data are adequate to support the storage
conditions and intervals from earlier field trials (MRID 42516500/01). 
However, in the most recent field trials, samples of roots and tops were
stored frozen for up to 14 months (MRID 45824401) or 13.5 months (MRID
46773001).  Each of these later field trials indicated that data were
available supporting frozen storage intervals of up to 24 months and
cited the following study: 

Wrede, A.  2001.  “Stability of Desmedipham and its Metabolite EHPC in
Sugar Beet Root and Leaf During Deep Freeze Storage of 24 Months, Bayer
CropScience Report No. C017679.”

However, these data have not been submitted to the Agency for review.

Conclusion:  

	1)  The 24-month storage stability study on sugar beets should be
submitted for review.

  

860.1400 Water, Fish, and Irrigated Crops

This guideline requirement is not relevant as there are no aquatic uses
for desmedipham. 

860.1460 Food Handling

This guideline requirement is not relevant as there are no-food handling
uses for desmedipham. 

860.1480 Meat, Milk, Poultry, and Eggs

  SEQ CHAPTER \h \r 1 Based on the reassess tolerance for sugar beet
tops, the maximum theoretical dietary burdens of desmedipham for beef
and dairy cattle are presented in Table 4.

Table 4.	Calculation of Maximum Dietary Burdens of Livestock to
Desmedipham Residues.

Feed Commodity	% Dry Matter1	% Diet1	Reassessed Tolerance (ppm)	Dietary
Contribution (ppm)2

Beef Cattle

Beet, sugar, tops	23	20	5	4.3

TOTAL BURDEN

20

4.3

Dairy Cattle

Beet, sugar, tops	23	10	5	2.2

TOTAL BURDEN

10

2.2

1 Table 1 (OPPTS Guideline 860.1000).  

2 Contribution = ([tolerance / % DM] X % diet) for beef and dairy cattle

The administered dose in the submitted ruminant metabolism study
represented 1.1x the maximum expected dietary burden to beef cattle and
2.3x the maximum expected dietary burden to dairy cattle. Because
Desmedipham residues in milk and all tissues in the metabolism study
were < 0.01 ppm, the Agency considers use of desmedipham on sugar beets
to be a 180.6(a)(3) situation for ruminants (i.e., there is no
expectation of finite residues in ruminant commodities).  Therefore, a
cattle feeding study is not required, and no tolerances for ruminant
commodities need be established.

Sugar beet commodities are not listed as poultry or swine feed items in
Table 1 (OPPTS 860.1000); therefore, no tolerances for desmedipham
residues in poultry or swine commodities are required.

860.1500 Crop Field Trials

D184329, D. Miller, 12/22/92

45824401.der, S. Kinard, 07/08/04

46773001.der, P. Y. Barnes, 12/28/06

The results from sugar beet field trials, which used the adequate
HPLC/UV or LC/MS/MS methods for sample analysis, are discussed below and
summarized in Table 5.  The Agency notes that Bayer is only supporting
the use of EC formulations on sugar beets.

Table 5.	Summary of Residue Data from Sugar Beet Field Trials with
Desmedipham.

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

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

MRID 42516500/01 3

Tops	1.3 lb/gal EC	1.95 (1x)	75	5	<0.05	6.54	6.54	0.12	1.38	2.88

MRID 45824401 4

Tops	1.3 lb/gal EC	1.18-1.23 (0.6x)	75-76	28	<0.05	0.24	0.23	0.025	0.042
0.054

Roots

28	<0.05	<0.05	<0.05	0.025	0.025	NA

MRID 46773001

Tops	1/3 lb/gal EC	1.93-2.09 (1x)	71-75	18	<0.05	0.135	0.100	0.025	0.045
0.037

Roots

18	<0.05	<0.05	<0.05	0.025	0.025	NA

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

2	HAFT = Highest Average Field Trial.

3	The Agency’s review of this submission did not address residues in
roots.

4             This study was conducted to support the use of multiple
“micro” applications at up to 0.2 lb ai/A/application.

	

MRID 42516501.   In the 5 field trials referenced in MRID 42516500/01
dated 1992 for growing zones 5, 7 and 10, desmedipham was applied to
sugar beets in side-by-side tests using the 70% WP and 1.3 lb/gal EC
formulations as two broadcast foliar applications at 0.975 lb
ai/A/application, one week apart, for a total of 1.95 lb ai/A (1x rate).
 Single control and treated samples of tops were harvested from each
test at 75 DAT.  Samples of tops were stored frozen for up to 8 months,
and were analyzed for residues of desmedipham using the adequate HPLC/UV
method (Desmedipham Method/R75).  The method LOQ is 0.05 ppm for tops.

 

Following two applications totaling 1.95 lb ai/A (1x rate), residues of
desmedipham in/on sugar beet tops at 75 DAT were <0.05-6.54 ppm for the
five samples from plots treated with the 1.3 lb/gal EC and 0.07 ppm to
13.86 ppm for the five samples from plots treated with the 70% WP. 
Average residues in/on tops were 1.38 ppm for the EC formulation and
2.97 ppm for the WP formulation. 

MRID 45824401.   In 14 field trials conducted during 2001 in growing
zones 5, 7, 8, 9, 10 and 11, desmedipham (1.3 lb/gal EC) was applied to
sugar beets as six broadcast foliar applications at 0.19-0.21 lb
ai/A/application, at RTIs of 4-6 days, for a total of 1.18-1.23 lb
ai/A/season (0.6x rate).  Applications were generally made beginning at
the 2 to 19 leaf stage and up to complete crop cover (BBCH 12-39).  All
applications were made using ground equipment and included the use of
methylated seed oil as an adjuvant at (1.5%, v/v).  Single control and
duplicate treated samples of tops and roots were harvested at 75-76 DAT.
 At two test sites in MN and CA, single treated and control samples of
roots and tops were also harvested at 45 to 46, 60, 90 and 105 DAT to
examine residue decline.  Samples of roots and tops were stored frozen
(≤0 ºC) for up to 14 months prior to analysis, and samples were
analyzed using an adequate LC/MS/MS method (Bayer Method AL/01/02).  The
method LOQ is 0.05 ppm for both roots and tops, and reported LOD is
0.016 ppm and 0.008 ppm for tops and roots, respectively.

Following six applications totaling ~1.2 lb ai/A (0.6x rate), residues
of desmedipham were <0.05 ppm in/on all 28 samples of sugar beet roots
and <0.05 ppm to 0.24 ppm in/on 28 samples of sugar beet tops harvested
at 75 to 76 DAT.  Only three samples of tops had residues above the LOQ
(0.08, 0.22, and 0.24 ppm).  The HAFT residues were <0.05 ppm for roots
and 0.23 ppm for tops, and average residues were 0.025 ppm (½LOQ) for
roots and 0.042 ppm for tops.  In the two residue decline trials,
residues were <LOQ in/on roots samples at all intervals from both trials
and were also <LOQ in/on tops at all intervals from the MN test.  In the
CA test, residues in/on tops declined from 0.25 ppm at 45 DAT to <LOQ by
90 DAT. 

(≤-5ºC) for up to 13.5 months prior to analysis, and samples were
analyzed using an adequate LC/MS/MS method (Bayer Method AL/01/02).  The
method LOQ is 0.05 ppm for both roots and tops, and the LOD is 0.008 ppm
and 0.023 ppm for tops and roots, respectively.

Following application at a 1x rate, residues of desmedipham in/on sugar
beets were <0.05 ppm for the 18 samples of roots and <0.05 ppm to 0.135
ppm for the 18 samples of tops harvested at 71-75 DAT, and only 5 of the
18 tops samples had residues >LOQ.  The HAFT residues were <0.05 ppm for
roots and 0.10 ppm for tops, and average residues were 0.025 ppm for
roots and 0.045 ppm for tops.

Conclusions.  Pending submission of the requested storage stability
data, the available sugar beet field trial studies are adequate.  The
earlier field trial data on tops (MRID 42516500/01) along with the more
recent field trial data on tops and roots (MRID 46773001) are sufficient
to support the current maximum use rate of desmedipham (EC) on sugar
beets, which allows for two applications totaling 1.95 lb ai/A.  
Although residue data for roots are available from only 9 of the
required 12 trials, the available root data are adequate as residues
in/on all 18 samples were below LOQ.  For the EC formulation, which is
the only type being supported, residues were <0.05 ppm to 6.54 ppm in/on
27 samples of sugar beet tops.  Adequate data are also available to
support the labeled use of up to six low rate applications at 0.2 lb
ai/A with the inclusion of methylated seed oil (1.5%, v/v) as an
adjuvant.

860.1520 Processed Food and Feed

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

  SEQ CHAPTER \h \r 1 An adequate sugar beet processing study is
available.  Residues of desmedipham were nondetectable (<0.05 ppm) in
sugar beet processed commodities (processed roots, cossettes, dried
pulp, refined sugar, and molasses) generated from sugar beet roots
bearing nondetectable residues following treatment at 2x the maximum
seasonal rate (the highest tolerated rate).  As residues were <LOQ in
the RAC and processed fractions following applications at the highest
tolerated rate, separate tolerances for sugar cane molasses, dried pulp,
and sugar are not required.

  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 ai/A,
which is ~1x the maximum use rate for sugar beets.

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 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)].    SEQ CHAPTER \h \r 1 The
existing tolerances for sugar beet roots and tops are listed in Table 6,
along with the Agency’s recommended reassessed tolerance levels. 

As Bayer is only supporting the use of EC formulations of desmedipham,
only residue data from trials using EC formulations will be used for
tolerance reassessment.  In the field trials conducted at a 1x rate,
residues in/on 27 samples of tops were <0.05ppm - 6.35 ppm, with 16
samples having residues <0.05 ppm, 10 samples having residues of 0.06
ppm to 2.19 ppm, and one sample having residues at 6.35 ppm.  Based on
the maximum residue value, the tolerance for tops should be reassessed
to 5 ppm.  The tolerance for roots can be reduced 0.1 ppm as residues
were <LOQ (<0.05 ppm) in/on all 18 samples of sugar beet roots.

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
recommended U.S. tolerances.

Table 6. 	Tolerance Reassessment Summary for Desmedipham.

Commodity	Existing Tolerance (ppm)	Recommended Tolerance (ppm)	Comments

Beet, sugar, roots	0.2	0.1	Following application of the EC formulation
at a 1x rate, residues were <0.05 ppm in/on 18 samples of roots and
<0.05-6.35 ppm in/on 27 samples of tops harvested around the labeled
75-day PHI.

Beet, sugar, tops	0.2	5.0

	

RDI:  P. Yvonne Barnes (11/07/2006), Donald Wilbur (11/20/2006).

References

  SEQ CHAPTER \h \r 1 DP Barcode:	D184329	

Subject:	Desmedipham 6(a)(2) Submission form Nor-Am Chemical Company
dated October 15, 1992.  SEQ CHAPTER \h \r 1 

From:		D. Miller 

To:		W. Allan

Dated:		12/22/92

MRID(s):	42516500 and 42516501

  SEQ CHAPTER \h \r 1 DP Barcode:	D213531	

Subject:	Desmedipham.  Outcome of 3/27/95 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

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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

 Reevaluated tolerance

 Other	Date:  08/25/2006

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

X No Codex proposal step 6 or above

 No Codex proposal step 6 or above for the crops requested	Petition
Number:  NA

DP Barcodes:   D327440

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

	Residue definition:  Desmedipham

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

Beet, sugar, roots	0.1

Beet, sugar, tops	5.0

	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: 
D327740

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