Document ID: EPA-HQ-OPP-2007-0116-0005
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-12-31T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

	Date:	25/SEP/2007

	Subject:	Dimethenamid-P.  Petition for Registration for Uses on
Turnips, Rutabagas, Radishes, Winter Squash, Pumpkins, and Hops. 
Summary of Analytical Chemistry and Residue Data.  Petition Number
6E7152

DP Num:	341886	Decision Number:	372743

PC Code:	120051	MRID Nos.:	47005001, 47005002, 47005003, 47005004

40 CFR 180.	464

Chemical Class:	Chloroacetamide herbicide

	

	From:	Debra Rate, Ph.D., Biologist

		Alternative Risk Integration and Assessment (ARIA)

		Risk Integration, Minor Use, and Emergency Response Branch (RIMUERB)

		Registration Division (RD) (7505P)

Through:	William Cutchin, Acting Branch Senior Scientist

		ARIA

	RIMUERB/RD (7505P)

			And

	

	Douglas Dotson, Ph.D., Chemist

	Registration Action Branch 2 (RAB2)

	Health Effects Division (HED) 7509P

	To:	Breann Hanson

		ARIA

		RIMUERB/RD (7505P)

  SEQ CHAPTER \h \r 1 This memorandum was originally prepared under
contract by Dynamac Corporation (submitted 7/24/2007).  The memorandum
has been reviewed by ARIA/RD and revised to reflect current Office of
Pesticide Programs (OPP) policies.

Executive Summary

Dimethenamid-P, which is a form of dimethenamid that is enriched in the
biologically active S-isomer (90:10, S:R), is a selective, preemergence
herbicide registered for the control of annual broadleaf and grass weeds
in a variety of field and vegetable crops.  Tolerances are established
for residues of dimethenamid,
(RS)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethylthien-3-yl)ac
etamide, in/on numerous raw agricultural commodities at 0.01 ppm, which
is the lowest limit of method validation (LLMV).  Tolerances are
established in 40 CFR §180.464(a) and (b) for both dimethenamid (50:50,
S:R) and dimethenamid-P (90:10, S:R).  As a result, tolerances that are
established for the proposed commodities will apply to both dimethenamid
and dimethenamid-P.  Hereafter in this document, both formulations will
be referred to as dimethenamid.

Dimethenamid is currently registered to BASF Corporation for use on a
variety of food/feed crops as a 6 lb/gal emulsifiable concentrate (EC,
Outlook® Herbicide; EPA Reg. No. 7969-156).  The Interregional Research
Project No. 4 (IR-4) is proposing new uses for dimethenamid-P on
radishes, turnips, rutabagas, pumpkins, winter squash, and hops. 
Dimethenamid (6 lb/gal EC) is being proposed for a single broadcast
postemergence application at up to 0.98 lb ai/A to radishes at the 2- to
4-leaf stage and to turnips and rutabagas at the 2- to 8-leaf stage. 
The specified preharvest intervals (PHIs) are 21 days for radishes
(roots and tops), 14 days for turnip and rutabaga tops, and 40 days for
turnip and rutabaga roots.  The proposed use on winter squash and
pumpkins is restricted to OR and WA and is for single preemergence
application at up to 0.98 lb ai/A, with a PHI of 90 days.  The proposed
use for hops is restricted to ID, OR and WA and is for a single
soil-directed or banded application between rows at up to 0.98 lb ai/A,
when hops are at the vegetative or early bloom stages.  The proposed PHI
for hops is 60 days.  All applications are to be made using ground
equipment; the use of aerial applications and chemigation are
prohibited.  In conjunction with these uses, IR-4 is proposing the
following permanent tolerances for dimethenamid:

Hops, dried cones	0.05 ppm

Pumpkin	0.01 ppm

Radish, roots	0.01 ppm

Radish, tops	0.01 ppm

Rutabaga, roots	0.01 ppm

Rutabaga, tops	0.1   ppm

Turnip, greens	0.1   ppm

Turnip, roots	0.01 ppm

Turnip, tops	0.1   ppm

Winter squash	0.01 ppm

  SEQ CHAPTER \h \r 1 The nature of dimethenamid residues in plants is
understood based on the adequate soybean, corn and sugar beet metabolism
studies.  The residue of concern for purposes of the tolerance
expression and risk assessment is dimethenamid per se.  The qualitative
nature of the residue in livestock is also understood based on the
adequate goat and hen metabolism studies.    SEQ CHAPTER \h \r 1
Considering the extensive metabolism of dimethenamid in animals, the
exaggerated dosing levels used in the animal metabolism studies, and the
expected low level of dietary exposure of livestock to dimethenamid,
ARIA has concluded that livestock feeding studies and tolerances for
animal commodities are not required at the present time.  

  SEQ CHAPTER \h \r 1 An adequate gas chromatograph/nitrogen-phosphorus
detection method (GC/NPD; AM-0884-0193-1) is available for enforcing
tolerances on plant commodities.  The LLMV is 0.01 ppm for the requested
plant commodities, except hops (which has an LLMV of 0.05 ppm).  This
method does not separate the R and S isomers of dimethenamid, and is
therefore adequate for both dimethenamid and dimethenamid-P.  As
tolerances are not required for animal commodities, no analytical
methods for animal commodities are required.

The residue data from the submitted turnip and radish field trials were
collected using the above GC/NPD enforcement method, and residue data
from the squash and hops field trials were collected using methods which
were derived from the enforcement method.  In each case, the method used
for data collection was adequately validated in conjunction with the
analysis of field trial samples.  In the turnip and radish field trials,
the statistically calculated limits of quantitation (LOQs) for
dimethenamid are 0.008 ppm for turnip tops, 0.004 for radish tops and
0.005 for turnip and radish roots.

In the squash field trials, residues of dimethenamid were determined
using a gas chromatography with electron capture detection (GC/ECD)
method (Method SAM 3002.01) that is a modification of the above
enforcement method.  The calculated LOQ for dimethenamid in squash is
0.005 ppm.

In the hops field trials,   SEQ CHAPTER \h \r 1 residues of dimethenamid
were determined using a gas chromatography with a mass selective
detector (GC/MSD)   SEQ CHAPTER \h \r 1 method.  Residues are analyzed
by GC/MSD using an external standard and the m/z 230 ion of
quantitation.  The statistically calculated LOQ is 0.034 ppm for
dimethenamid in hops.

The available turnip, radish, winter squash and hops field trial data
are adequate and support the proposed use patterns.  The number and
geographic distribution of the field trials are adequate and the
appropriate samples were collected at the proposed PHIs.  Samples were
analyzed for the residues of concern using adequate methods, and the
sample storage conditions and intervals are supported by the available
storage stability data.

In the eight adequate turnip field trials, dimethenamid (6 lb/gal EC)
was applied to turnips during vegetative development as a single
post-emergence broadcast application at 0.94-1.03 lb ai/A (1x rate)
using ground equipment.  Residues of dimethenamid were non-detectable
in/on all 16 root samples harvested at 28-40 days after treatment (DAT),
and <0.01-0.093 ppm in/on 16 samples of tops harvested at 14-16 DAT. 
Average residues were 0.018 ppm in tops and <0.01 ppm in roots.  The
field trial data on turnips will support the equivalent use on
rutabagas.  Because the radish, top and turnip, top data are over 10x
difference (0.01 ppm and 0.1 ppm, respectively) not the 5x defined in
OPP policy, the data do not support a crop group tolerance.

In the six radish field trials, dimethenamid (6 lb/gal EC) was applied
to radishes at the 2- to 4-leaf stage as a single post-emergence
broadcast application at 0.96-1.03 lb ai/A (1x rate) using ground
equipment.  Residues of dimethenamid were <0.01 ppm in/on all 12 samples
of radish tops and <0.01 ppm in/on all 12 samples of radish roots
harvested at 15-21 DAT.

In the three winter squash field trials conducted in EPA growing Region
12, dimethenamid (6 lb/gal EC) was applied to winter squash as a single
preemergence broadcast application at 0.95-1.00 lb ai/A (1x rate) using
ground equipment.  Residues of dimethenamid were <0.01 ppm in/on all 6
samples of winter squash harvested at normal crop maturity, 108-131 DAT.
 The field trial data on winter squash will support the equivalent use
on pumpkins.

In the three hops field trials, dimethenamid (6 lb/gal EC) was applied
to hops during vegetative development through early bloom as a single
soil directed application at 0.97-1.02 lb ai/A (1x rate) using ground
equipment.  Residues of dimethenamid were <0.05 ppm in/on all 6 samples
of dried hop cones harvested at 60-61 DAT.

No processing studies were submitted with the current petition as none
of the proposed uses include crops having regulated processed
commodities.  An adequate confined rotational crop study is available
which supports the current label restrictions for rotational crops. 

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

No deficiencies were noted in the subject petition that would preclude
establishing permanent tolerances for dimethenamid on the proposed crops
provided the petitioner addresses the deficiencies noted below:

1.	A revised Section B must be provided.  Currently, the proposed uses
on rutabagas (roots and tops) are associated with the uses on radishes
(roots and tops).  This should be revised, as uses on rutabagas (roots
and tops) should only be addressed in conjunction with the proposed uses
on turnips (tops and roots).  

2.	Although the proposed label directions for turnips and rutabagas
specify a 40-day PHI for roots, ARIA notes that the available turnip
field trial data would support lowering the PHI for roots to 30 days,
which matches the proposed use in the submitted Section B.

Provided the deficiencies are adequately addressed, ARIA recommends
establishing permanent tolerances for residues of dimethenamid at 0.01
ppm on radish roots and tops, turnip roots, rutabaga roots, pumpkins and
winter squash.  Tolerances should also be established at 0.1 ppm on
turnip tops and rutabaga tops, and at 0.05 ppm on hops, dried cones.  It
should be noted that the data submitted for radish, turnip and rutabaga,
while adequate for individual crop tolerances, are do not support a crop
group tolerance.  All of the recommended tolerances should be placed in
40 CFR §180.464(a), without restriction, except for the tolerances for
pumpkins and winter squash which should be placed in 40 CFR
§180.464(c), as the use on these crops is restricted to OR and WA
(Table 7).  The data submitted for hops support a national tolerance
placing it in 40 CFR §180.464(a), even though the labeled use submitted
by the petitioner restricts distribution to ID, OR and WA (>95% of US
hops production).   

Background

Dimethenamid and dimethenamid-P are selective, preemergence
chloroacetamide-type herbicides registered for the control of annual
broadleaf and grass weeds in a variety of field and vegetable crops. 
Dimethenamid is an equal part mixture of the R and S-isomers (50:50,
S:R); whereas, dimethenamid-P is enriched in the biologically active
S-isomer (90:10, S:R).  In the U.S., both herbicides are registered to
BASF Corporation and are marketed under the trade names Frontier,
Outlook, Optill, and Guardsman.  Both herbicides are formulated as ECs
at concentrations of 1.7-7.5 lb/gal.  These formulations can be applied
as banded or broadcast pre-plant, preemergence and/or a postemergence
applications using ground or aerial equipment.

Permanent tolerances are established for residues of dimethenamid,
(RS)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethylthien-3-yl)ac
etamide, applied as either the 50:50 or 90:10 S:R isomers, in/on
numerous raw agricultural commodities at 0.01 ppm, which is the LLMV [40
CFR §180.464(a)].  A time-limited tolerance has also been established
for dimethenamid at 0.01 ppm in/on winter squash, which is set to expire
on 30/JUN/2009 [40 CFR §180.464(b)].  Tolerances for residues of
dimethenamid in animal commodities have not been established.

IR-4 has submitted a petition (PP# 6E7152) supporting the use of
dimethenamid-P (6.0 lb/gal EC) on turnips, rutabagas, radishes, hops,
winter squash and pumpkins.  The nomenclature and physicochemical
properties of dimethenamid are presented below in Tables 1 and 2.

Table 1.	Dimethenamid-P Nomenclature.

Compound	

Common name	  SEQ CHAPTER \h \r 1 Dimethenamid-P (or S-Dimethenamid);
90:10, S:R isomer ratio

Company experimental name	BAS 656H; SAN 1289

IUPAC name	  SEQ CHAPTER \h \r 1
(S)-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)
acetamide

CAS name
2-chloro-N-(2,4-dimethyl-3-thienyl)-N-[(1S)-2-methoxy-1-methylethyl]
acetamide

CAS registry number	163515-14-8

End-use product (EP)	6 lb/gal EC (Outlook® Herbicide; EPA Reg. No.
7969-156)

Table 2.	Physicochemical Properties of Dimethenamid.

Parameter	Value	Reference

Melting point/range	<-50ºC	MRID 47005001

pH	3.3 (in 1% aqueous emulsion)

	Density	1.195 g/mL

	Water solubility	1449 ±17 mg/L (pH 6.16)

	Solvent solubility	20.8g/100 mLin hexane; soluble in all proportions in
tetrahydrofuran, isopropyl alcohol, acetone, acetonitrile, DMSO, DCM,
toluene and n-octanol.

	Vapor pressure	1.88 (±0.29) x 10-5 mm Hg

	Dissociation constant, pKa	No Dissociation

	Octanol/water partition coefficient 	77.6 and 1.89 (POW and log POW)

	UV/visible absorption spectrum	ε = 7560; 33 nm

	

860.1200  Directions for Use

IR-4 is proposing the use of dimethenamid-P, formulated as a 6 lb/gal EC
(Outlook® Herbicide; EPA Reg. No. 7969-156), on turnips, rutabagas,
radishes, winter squash, pumpkins and hops. The uses on winter squash
and pumpkins are restricted to the states of OR and WA, and the use on
hops is restricted to the states of ID, OR and WA.  The petitioner
provided example labels containing the proposed use directions which are
summarized in Table 3.

Table 3.  Summary of Directions for Use of Dimethenamid-P.

Applic. Timing, Type, and Equip. 1	Formulation

[EPA Reg. No.]	Applic. Rates 

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

(lb ai/A)	PHI

(days)	Use Directions and Limitations 2

Hops (only in ID, OR and WA)

Directed or banded post-emergence application from vegetative to early
bloom stages, using ground equipment 	6.0 lb/gal EC

[7969-156]	0.56-0.98	1	0.98	60	This use is restricted to the states of
ID, OR and WA.

Radish

Broadcast post-emergence application when plants are at 2- to 4-leaf
stage, using ground equipment 	6.0 lb/gal EC

[7969-156]	0.56-0.98	1	0.98	21

	Turnip and Rutabaga

Broadcast post-emergence application when plants are at 2- to 8-leaf
stage, using ground equipment 	6.0 lb/gal EC

[7969-156]	0.56-0.98	1	0.98	tops – 14

roots - 40

	Winter Squash and Pumpkins (only in OR and WA)

Broadcast preemergence application using ground equipment	6.0 lb/gal EC

[7969-156]	0.56-0.98	1	0.98	90	This use is restricted to the states of
OR and WA

1	Do not apply by air or through any irrigation systems.

2	Crops listed on the main label may be replanted at anytime, and
fall-seeded cereal grains may be planted 4 months after application.  
All other crops may be planted the following spring.

Conclusions:  The proposed use directions are adequate and are supported
by the available field trial data.  However, the petitioner must submit
a revised Section B.  Currently, the Section B associates the proposed
uses on rutabaga (roots and tops) with that of radish.  However, the
proposed uses of rutabaga (roots and tops) should only be addressed in
conjunction with the proposed uses on turnips (tops and roots).  In
addition, although the proposed label directions for turnips and
rutabagas specify a 40-day PHI for roots, ARIA notes that the available
turnip field trial data would support lowering the PHI for roots to 30
days, as requested in the Section B.

860.1300 Nature of the Residue – Plant

HED Metabolism Committee Memo, M. Flood, 10/NOV/1992

HED Metabolism Committee Memo, M. Bradley, 08/DEC/1993

45189703.der (sugar beet metabolism), 14/APR/2004, D. Dotson

DP Num: 304790, R. Griffith et al., 12/AUG/2004

  SEQ CHAPTER \h \r 1 The nature of the residue in plants is adequately
understood based on the available soybean, corn and sugar beet
metabolism studies.  The soybean and corn metabolism studies were
reviewed by the HED Metabolism Committee, which concluded that the
metabolism of dimethenamid in plants involves conjugation with
glutathione, with subsequent transformation of the glutathione moiety to
yield a variety of metabolites.  The residue of concern for purposes of
the tolerance expression (and risk assessment) was determined to be
dimethenamid per se.

The sugar beet metabolism study was reviewed later in conjunction with a
petition for use of dimethenamid-P on various root, tuber, corm and bulb
vegetables.  Following three early season foliar applications of
[3-14C-thienyl]dimethenamid to sugar beets at a total rate of 1.2 lb
ai/A, total radioactive residues (TRR) were 0.078 and 0.284 ppm in/on
sugar beet roots and tops harvested 126 days after the last treatment. 
The metabolite profile was similar for roots and tops, and dimethenamid
was not detected in/on either commodity.  For both roots and tops, the
majority of 14C-residues were characterized as minor unknowns each
present at ≤8% of the TRR.  One unknown polar fraction accounted for
>10% of the TRR in roots, but was present at <0.01 ppm.  The metabolic
pathway for [14C]dimethenamid in sugar beets is complex, but proceeds
via a pathway similar to that observed in corn and soybeans.  However,
two metabolites not identified in corn or in soybean were found in sugar
beets.  These are the sulfoxide of the cysteine conjugate and the
N-malonyl conjugate of the cysteine conjugate, which together accounted
for <6 % of the TRR in sugar beets.  The [14C]dimethenamid sugar beet
metabolism study is adequate.  Parent, dimethenamid, was extensively
metabolized and not detected in sugar beet roots or tops.  

Conclusions:  After considering the extensive metabolism of dimethenamid
in plants (soybean, corn and sugar beet) HED concluded that the residue
of concern for purposes of the tolerance expression (and risk
assessment) was determined to be dimethenamid per se.  The nature of the
residue in plants is adequately understood and adequately supports the
proposed new uses associated with this petition (PP# 6E7152).  

860.1300 Nature of the Residue - Livestock

HED Metabolism Committee Memo, M. Flood, 10/NOV/1992

DP Num: 304790, R. Griffith et al., 12/AUG/2004

The qualitative nature of the residue in livestock is understood based
on the available goat and poultry metabolism studies.    SEQ CHAPTER \h
\r 1 In the ruminant metabolism study, a dairy goat was dosed orally for
4 days with [14C]dimethenamid at levels equivalent to 223 ppm (1,335x
the dietary burden).  Total radioactive residues were 16.6 ppm in liver,
9.9 ppm in kidneys, 0.97 ppm in muscle and fat, and 0.98 ppm in milk. 
[14C]Dimethenamid was extensively metabolized and identification of
metabolites was limited.  The principle metabolites identified in milk
and tissues included:  M17 in kidney (9% TRR), liver (2.7% TRR), muscle
(11.4% TRR), fat (5.4% TRR), and milk (5.2% TRR); the cysteine conjugate
of parent in kidney (1% TRR), liver (7.2% TRR), muscle (14.2% TRR), and
milk (11.2% TRR); and the glutathione conjugate of parent in kidney (5%
TRR), liver (2.2% TRR), muscle (8.3% TRR), fat (2.1% TRR), and milk
(7.9% TRR).  Metabolite M7 was also identified as a major component in
kidneys (24.1% TRR) and milk (24.2% TRR), and Metabolite M22 was
identified in liver (6.1% TRR).  None of the remaining unknown
components were present at more than 10% of the TRR in milk or any
tissue.

In the poultry metabolism study, three hens were dosed orally for 4 days
with [14C]dimethenamid at levels equivalent to 167 ppm (17,000x maximum
dietary burden (MDB) of 0.01 ppm).  Total radioactive residues were 8.33
ppm in liver, 0.58 ppm in muscle, 0.29 ppm in fat, 0.30 ppm in egg
whites and 0.62 ppm in egg yolks.  The metabolism of [14C]dimethenamid
in hens was extensive, with parent only being identified in fat (34.9%
TRR).  Other than parent in fat, no one compound appears to account for
more than 10% of the TRR in any given tissue.  Although only limited
identification of 14C-residues was achieved, the poultry metabolism
study was deemed adequate because the dosing level was highly
exaggerated compared to the MDB and the extensive metabolism of
dimethenamid resulted in numerous minor metabolites (<10% TRR).

Conclusions:  After considering the extensive metabolism of dimethenamid
in animals, the exaggerated dosing levels used in the ruminant and
poultry metabolism studies, and the expected low level of dietary
exposure of livestock to dimethenamid, HED concluded that tolerances
(and risk assessment) are not required for animal commodities.  The
proposed uses, which include turnip tops, do not alter the above
determinations regarding the need for tolerances on meat and milk.

860.1340 Residue Analytical Methods

Enforcement methods

  SEQ CHAPTER \h \r 1 An adequate enforcement method is available for
determining residues of both dimethenamid and dimethenamid-P residues in
plant commodities.  The GC/NPD method (AM-0884-0193-1) has been
validated by the Agency and submitted for publication in FDA’s
Pesticide Analytical Manual, Volume II.  The method does not separate
the R and S isomers of dimethenamid, and the LOQ is 0.01 ppm.  As
tolerances are not required for animal commodities, no analytical
methods for animal commodities are required.

Data collection methods

Samples of roots and tops from the turnip and radish field trials were
analyzed for residues of dimethenamid-P using the current tolerance
enforcement method (  SEQ CHAPTER \h \r 1 AM-0884-0193-1).  For this
method,   SEQ CHAPTER \h \r 1 residues are extracted with methanol:water
(95:5, v:v), purified using a C18 SPE column, and concentrated to an
aqueous fraction.  Residues are further cleaned up using an Extrelut
column eluted with toluene, and a silica gel column eluted with ethyl
acetate:cyclohexane (1:4, v:v).  The eluate is then concentrated, and
residues are redissolved in toluene and analyzed by GC/NPD using an
external standard.  The LLMV for dimethenamid is 0.01 ppm in roots and
tops.  The statistically calculated LOQs were 0.008 ppm for turnip tops,
0.004 for radish tops and 0.005 for turnip and radish roots.

In the squash field trials, residues of dimethenamid were determined
using a GC/ECD method (Method SAM 3002.01) that is a modification of the
above enforcement method that eliminated the C18 SPE cleanup step,
replaced toluene with hexane, and used ECD instead of NPD. The LLMV was
0.01 ppm and the calculated LOQ was 0.005 ppm.

In the hops field trials,   SEQ CHAPTER \h \r 1 residues of dimethenamid
were determined using a   SEQ CHAPTER \h \r 1 GC/MSD method which was
derived from the tolerance enforcement method.  For this method,   SEQ
CHAPTER \h \r 1 residues are extracted from hops with methanol:water
(95:5, v:v), filtered, and initially cleaned up by elution through a
Nexus SPE cartridge using methanol:water (80:20, v:v).  Residues are
then concentrated to an aqueous remainder, diluted with water and saline
solution, and partitioned into ethyl acetate.  Residues are next
concentrated to dryness, redissolved in ethyl acetate:hexane (20:80,
v:v), and further cleaned up by elution through a NH2 SPE cartridge. 
Residues are then concentrated to dryness, redissolved in ethyl acetate
with 0.2% corn oil, and analyzed by GC/MSD using an external standard. 
The m/z 154, 230, and 232 ions were monitored for identification, and
the m/z 230 ion was used for quantifying residues.  The LLMV for
dimethenamid is 0.05 ppm in dried hops, and the statistically calculated
LOQ is 0.034 ppm.

Conclusions.  An adequate enforcement method is available for
determining dimethenamid (and dimethenamid-P) residues in plant
commodities.  The residue data from the submitted field trials were
collected using methods that were adequately validated in conjunction
with the analysis of field trial samples.

860.1360 Multiresidue Methods

  SEQ CHAPTER \h \r 1 The FDA PESTDATA database dated NOV/2001 (PAM
Volume I, Appendix I) indicates that dimethenamid is not recovered using
Multiresidue Methods Section 303 (Mills, Onley, and Gaither Method;
Protocol E, nonfatty food) or Section 304 (Mills Method; Protocol F,
fatty food).

860.1380 Storage Stability

In the current petition, storage stability studies were conducted
concurrently with the various field trials.  Upon receipt by the
analytical laboratory, control samples of each crop matrix were
fortified with dimethenamid at 0.1-0.5 ppm and stored under the same
conditions as the field trial samples.  At the end of the analytical
phase, stored fortified samples were analyzed in triplicate along with
freshly fortified samples and controls.  No 0-day analyses were
conducted.

ozen storage (≤-18ºC) for up to 24 months in turnip roots and tops,
20.5 months in radish roots and tops, 2.2 months in winter squash, and
11.5 months in dried hops (Table 4).

Conclusions:  The available storage stability data are adequate and
support the sample storage conditions and intervals from the submitted
field trials.

Table 4.	Summary of Storage Conditions and Durations of Samples from
Crop Field Trials.  

Crop Matrix 	Storage Temperature  (°C)	Actual Storage Duration

(months)	Interval of Demonstrated Storage Stability (months)

Turnip tops	-20	13.5-20	24

Turnip roots

13.3-20	24

Radish tops	-20	19.4-20.3	20.7

Radish roots

18.9-20.3	20.5

Winter squash	-18	1-2	2.2

Hops, dried cones	-18	12.2-12.7			11.5

  SEQ CHAPTER \h \r 1 860.1400 Water, Fish, and Irrigated Crops

This guideline requirement is not relevant to the current petition as no
aquatic uses are being proposed for dimethenamid. 

860.1460 Food Handling

This guideline requirement is not relevant to the current petition as no
food handling uses are being proposed for dimethenamid. 

860.1480 Meat, Milk, Poultry, and Eggs

HED Metabolism Committee Memo, M. Flood, 10/NOV/1992

DP Num: 304790, R. Griffith et al., 12/AUG/2004

In the current petition, the only new potential livestock feedstuff is
turnip tops.  Based on the recommended and established tolerances for
dimethenamid on feedstuffs, and the most recent guidance from HED
(October 2006) concerning revisions of feedstuffs in Table 1 (OPPTS
860.1000) and constructing reasonably balanced diets for livestock, the
MDBs were calculated to be 0.017 ppm for beef cattle, 0.016 ppm for
dairy cattle, and 0.01 ppm for poultry and swine (Table 5) (e-mail: J.
Stokes to D. Rate, 23/AUG/2007).

Table 5.   Calculation of Maximum Dietary Burdens of Livestock for
Dimethenamid Residues. (e-mail: J. Stokes to D. Rate, 23/AUG/2007)

Feedstuff	Dietary 1 Component	% Dry Matter 2	% Diet 2	Recommended
Tolerance (ppm)	Dietary Contribution (ppm) 3

Beef Cattle  R: 15%; CC:  75 %;  PC: 10%

grass, straw	R	88	10	0.01	0.0011

beet, sugar, dried pulp	R	88	5	0.01	0.0006

corn, field, grain/ milled bypdts/

sorghum, grain, grain	CC	85	70	0.01	0.0082

beet, sugar, molasses	CC	75	5	0.01	0.0007

soybean seeds	PC	92	10	0.01	0.0011

TOTAL BURDEN

	100

0.017

Dairy Cattle  R: 45%; CC: 45 %;  PC: 10%

grass, straw	R	88	10	0.01	0.0011

corn, field, forage/silage	R	40	30	0.01	0.0075

beet, sugar, dried pulp	R	88	5	0.01	0.0006

corn, field, grain/ milled bypdts/

sorghum, grain, grain	CC	85	40	0.01	0.0047

beet, sugar, molasses	CC	75	5	0.01	0.0006

soybean seeds	PC	92	10	0.01	0.0011

TOTAL BURDEN

	100

0.016

Poultry   CC: 75 %;  PC: 25 %

corn, field, grain/ milled bypdts/

sorghum, grain, grain	CC	--	75	0.01	0.0075

soybean seeds/peanut meal	PC

25	0.01	0.0025

TOTAL BURDEN

	100

0.010

Swine CC: 85 %;  PC: 15 %

corn, field, grain/ milled bypdts/

sorghum, grain, grain	CC	85	85	0.01	0.0085

soybean seeds/peanut meal	PC

15	0.01	0.0015

TOTAL BURDEN

	100

0.010

1	R = roughage, CC = carbohydrate concentrate, and PC = protein
concentrate.

2	Table 1 (OPPTS Guideline 860.1000).  

3	Contribution = ([tolerance /% DM] X % diet) for beef and dairy cattle;
contribution = ([tolerance] X % diet) for poultry and swine. 

There are no available livestock feeding studies with dimethenamid or
dimethenamid-P.  However, HED has previously concluded that tolerances
(and risk assessment) are not required for dimethenamid residues in
livestock commodities.  After considering the   SEQ CHAPTER \h \r 1
extensive metabolism of dimethenamid in animals, the exaggerated dosing
levels used in the animal metabolism studies, and the expected low level
of dietary exposure of livestock to dimethenamid, HED concluded that
residues of dimethenamid were unlikely to be quantifiable in livestock
commodities [40 CFR §180.6(a)(3)] (HED Metabolism Committee Memo, M.
Flood, 10/NOV/1992).  At the time of this decision the MDB was 0.019 ppm
for cattle and 0.01 ppm for poultry and swine.  Therefore, no feeding
studies or tolerances are presently required.

860.1500 Crop Field Trials

47005001.der, D. Rate, 13/AUG/2007 (turnip)

47005002.der, D. Rate, 13/AUG/2007  (radish)

47005003.der, D. Rate, 13/AUG/2007 (winter squash)

47005004.der, D. Rate, 13/AUG/2007 (hops)

IR-4 has submitted field trial data on turnips, radishes, winter squash,
and hops to support national uses of dimethenamid-P on turnips,
rutabagas, radishes, and hops and regionally restricted uses on winter
squash and pumpkins.    SEQ CHAPTER \h \r 1 The results from these
studies are discussed below and summarized in Table 6. 

Table 6.	Summary of Residue Data from Crop Field Trials with
Dimethenamid-P (6 lb/gal EC).

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

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

Turnip tops	0.95-1.01	14-16	16	<0.01	0.093	0.072	0.008	0.018	0.022

Turnip roots

28-40	16	<0.01	<0.01	<0.01	0.01	0.01	--

Radish tops	0.96-1.04	15-21	12	<0.01	<0.01	<0.01	0.01	0.01	--

Radish roots

	12	<0.01	<0.01	<0.01	0.01	0.01	--

Winter squash	0.95-1.00	108-131	6	<0.01	<0.01	<0.01	0.01	0.01	--

Hops, dried cones	0.97-1.02	60-61	6	<0.01	<0.01	<0.01	0.01	0.01	--

1	The statistically calculated LOQs for dimethenamid are 0.008 and 0.005
for turnip tops and roots, 0.004 and 0.005 ppm for radish tops and
roots, 0.005 ppm for squash, and 0.034 ppm for hops.    For calculating
the median, mean and standard deviation the LLMV (0.01 ppm) was used for
non-detectible (ND) residue values. 

2	HAFT = Highest average field trial result.

Turnips  In nine field trials conducted during 2001-2002 in NAFTA
growing Zones 1A (NS; 1 trial), 2 (NC, GA, TN; 3 trials), 5 (OH, ON; 2
trials), 5B (QC; 1 trial), 6 (TX; 1 trial) and 10 (CA; 1 trial).  One
trial (QC05) was not conducted under good laboratory practice (GLP)
conditions; therefore, the results were not included in the summary
table or tolerance calculations.  At each test site, dimethenamid-P (6
lb/gal EC) was applied to turnips as a single post-emergence broadcast
application at a rate of 0.94-1.03 lb ai/A (1x rate) during vegetative
development.  Applications were made using ground equipment at volumes
of 21-30 gal/A, and did not include the use of any spray adjuvants. 
Single control and duplicate treated samples of turnip tops were
collected from each test at 14-16 DAT, and root samples were collected
at 28-33 DAT, with the exception of one site (40 DAT).  Samples were
stored frozen for up to 20 months prior to analysis.  The storage
intervals are supported by the available storage stability data. 

The GC/NPD method (AM-0884-0193-1) used to determine residues of
dimethenamid in/on turnip tops and roots was adequately validated in
conjunction with the field trials.  The statistically calculated LOQ is
0.008 ppm for tops and 0.005 ppm for roots, and the calculated LOD is
0.0027 ppm for tops and 0.0016 ppm for roots.  The LLMV for turnip
matrices was shown to be 0.01 ppm for dimethenamid-P with recovery
ranges from 107 to 115% for tops and 91 to 102% for roots.

Following a single post-emergence broadcast application of
dimethenamid-P (EC) at 1x the proposed use rate, residues of
dimethenamid were 0.01-0.093 ppm in/on 13 samples of tops and <0.01 ppm
in all 16 samples of roots.  Residues were >LLMV in only 3 out of 16
samples of tops.  Average residues were 0.018 ppm in tops and <0.01 ppm
in roots.

Radishes  In six field trials conducted during 2002 in EPA growing
Regions 1, 3, 5, 10 and 11, dimethenamid-P (6 lb/gal EC) was applied to
radishes at the 2-4 leaf stage as a single post-emergence broadcast
application at a rate of 0.96-1.03 lb ai/A (1x rate).  Applications were
made using ground equipment at volumes of 21-30 gal/A, and did not
include the use of any spray adjuvants.  Single control and duplicate
treated samples of radish tops and roots were collected from each test
site at 15-21 DAT.  Samples were stored frozen for up to 20 months prior
to analysis, and a concurrent storage stability study was conducted
supporting the stability of dimethenamid in radish tops and roots at
-20ºC for up to 20 months.

The GC/NPD method (AM-0884-0193-1) used to determine residues of
dimethenamid in/on radish tops and roots was adequately validated in
conjunction with the analysis of field trial samples.  The calculated
LOQ is 0.004 ppm for tops and 0.005 ppm for roots and the calculated LOD
is 0.0013 ppm for tops and 0.0015 ppm for roots.  The LLMV for radish
matrices was shown to be 0.01 ppm for dimethenamid-P with recovery
ranges from 92 to 95% for tops and 90 to 103% for roots.

Following a single post-emergence broadcast application of
dimethenamid-P (EC) to radishes at 1x the proposed use rate, residues of
dimethenamid were <0.01 ppm in/on all 12 samples of radish tops and
<0.01 ppm in/on all 12 samples of radish roots harvested at 15-21 DAT.

Winter Squash  In three field trials conducted during 2002 in EPA
growing Region 12, dimethenamid-P (6 lb/gal EC) was applied to winter
squashes as a single preemergence broadcast application at a rate of
0.95-1.00 lb ai/A (1x use rate).  Applications were made using ground
equipment at volumes of 20-27 gal/A, and did not include the use of any
spray adjuvants.  Single control and duplicate treated samples of squash
were collected from each test site at normal maturity, 108-131 DAT. 
Samples were stored frozen for up to 2 months prior to analysis.  This
storage interval is supported by the available storage stability data.

 

The GC/ECD method (SAM 3002.01) used to determine residues of
dimethenamid in/on squash was adequately validated in conjunction with
the analysis of field trial samples.  The statistically calculated LOQ
and LOD were 0.005 and 0.002 ppm, respectively.  The LLMV for winter
squash matrices was shown to be 0.01 ppm for dimethenamid-P with a
recovery range of 65 to 78%, averaging 74%.

Following a single preemergence application of dimethenamid-P (EC) at 1x
the proposed use rate, residues of dimethenamid were <0.01 ppm in/on all
6 samples of winter squash harvested at maturity, 108-131 DAT.  

Hops  In three field trials conducted during 2003 in EPA growing Regions
11 and 12, dimethenamid-P (6 lb/gal EC) was applied to hops as a single
soil-directed application during vegetative development through early
bloom, at a rate of 0.97-1.02 lb ai/A (1x rate).  Applications were made
using ground equipment at volumes of 29-32 gal/A, and did not include
the use of any spray adjuvants.  Control and duplicate treated samples
of fresh hop cones were collected from each test site at 60-61 DAT, and
dried within one day of harvest using commercial dryers.  Samples of
dried hop cones were stored frozen for up to 12.7 months prior to
analysis, and a concurrent storage stability study was conducted
supporting the stability of dimethenamid in squash at -18ºC for up to
11.5 months.

The GC/MSD method used to determine residues of dimethenamid in/on hops
was adequately validated in conjunction with the analysis of field trial
samples.  The statistically calculated LOQ and LOD are 0.034 and 0.011
ppm, respectively.  The LLMV for hops was shown to be 0.05 ppm for
dimethenamid-P with a recovery range of 95 to 99%.

Following a single soil-directed application of dimethenamid-P (EC) to
hops at 1x the proposed use rate, residues of dimethenamid were <0.05
ppm in all 6 samples of dried hop cones.

Conclusions  The turnip, radish, winter squash and hops field trial data
are adequate and support the proposed use patterns.  Adequate numbers of
tests were conducted on each crop in the appropriate geographical
regions.  Samples were analyzed for the residue of concern using
adequate methods, and the sample storage conditions and intervals are
supported by the available storage stability data.

With the exception of turnip tops, residues of dimethenamid were <LLMV
in/on all samples of radish roots and tops (<0.01 ppm), dried hop cones
(<0.05 ppm), winter squash (<0.01 ppm) and turnip roots (<0.01 ppm). 
Residues in/on turnip tops were <0.01-0.093 ppm, with only 3 of 16
samples having residues above the LLMV.  

As the LLMV for radishes, turnips, and squash is 0.01 ppm, the above
data will support tolerances of 0.01 ppm for radish roots and tops,
turnip roots, and winter squash (restricted to OR and WA).  Tolerances
should be set at 0.1 ppm for turnip tops (See Attachment III, MRL
Calculator), and at 0.05 ppm for hops (hops LLMV <0.05 ppm).  The
residue data on winter squash can be translated to support a regional
tolerance (OR and WA) of 0.01 ppm tolerance on pumpkins, and the residue
data on turnips can be translated to support similar tolerances on
rutabaga roots (0.01 ppm) and tops (0.1 ppm).  

860.1520 Processed Food and Feed

There are no regulated processed commodities associated with the
proposed uses of dimethenamid-P on hops, radishes, turnips, rutabagas,
winter squash or pumpkins.

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

Analytical standards for dimethenamid and dimethenamid-P are currently
available in the National Pesticide Standards Repository.

  SEQ CHAPTER \h \r 1 860.1850 and 860.1900 Confined and Field
Accumulation in Rotational Crops

DP Num: D184986, M. Flood, 07/APR/1993

DP Num: D304790, R. Griffith et al., 12/AUG/2004

Based on the current and proposed uses of dimethenamid,   SEQ CHAPTER \h
\r 1 requirements for confined/field accumulation in rotational crops
are satisfied based on the acceptable confined rotational crop study. 
The submitted study includes data on winter wheat planted 141 DAT,
lettuce planted 322 DAT, and carrots planted 332 DAT.  The maximum
concentration of any metabolite/degradate in harvested wheat was 0.01
ppm for the sulfoxide of thiolactic acid conjugate.  Based on these
data, HED determined that a 4-month rotational interval is adequate for
fall-seeded cereal grains, and other crops may be planted the following
spring.  These recommendations are consistent with the rotational crop
restrictions on the current label for the 6 lb/gal EC formulation of
dimethenamid-P (see Table 3). 

860.1550 Proposed Tolerances

The Agency has determined that the residue of concern in plants is
dimethenamid per se (M. Flood, 10/NOV/1992; and M. Bradley,
08/DEC/1993).  Permanent tolerances are established for residues of
dimethenamid,
(RS)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethylthien-3-yl)ac
etamide, applied as either the 50:50 or 90:10 S:R isomers, in/on
numerous raw agricultural commodities at 0.01 ppm, which is the LLMV [40
CFR §180.464(a)].  A time-limited tolerance has also been established
for dimethenamid at 0.01 ppm in/on winter squash, which is set to expire
on 30/JUN/2009 [40 CFR §180.464(b)].  Tolerances for residues of
dimethenamid in animal commodities have not been established.

Adequate residue data are available to support the proposed tolerances. 
With the exception of turnip tops, residues of dimethenamid were <LLMV
in/on all samples of radish roots and tops (<0.01 ppm), dried hop cones
(<0.05 ppm), winter squash (<0.01 ppm) and turnip roots (<0.01 ppm). 
Residues in/on turnip tops were <0.01-0.093 ppm, with only 3 of 16
samples having residues above the LLMV.  

As the LLMV for radishes, turnips, and squash is 0.01 ppm, the above
data will support tolerances at 0.01 ppm for radish roots and tops,
turnip roots, and winter squash (Table 7).  Tolerances should be set at
0.1 ppm for turnip tops, and at 0.05 ppm for hops.  The residue data on
winter squash can be translated to support a 0.01 ppm tolerance on
pumpkins.  As described above, the residue data on turnips should be
translated to support similar tolerances on rutabaga roots (0.01 ppm)
and tops (0.1 ppm).  As data on winter squash were only provided from
EPA growing Region 12, regionally restricted tolerances (OR and WA)
should be established for pumpkins and winter squash (Table 7).  The
Section 18 tolerance for winter squash should not be revoked.

Based on data from the ruminant and poultry metabolism studies and the
calculated MDB for livestock to dimethenamid residues, tolerances for
livestock commodities are not required at the present time.

There are no established or proposed Codex, Canadian or Mexican maximum
residue limits (MRLs) for dimethenamid on any of the crops/commodities
being proposed in this petition (see attached international residue
limit (IRL) status sheet).  Therefore, there is no question about
compatibility of the proposed tolerances.

Table 7. 	Tolerance Summary for Dimethenamid

Commodity	Proposed Tolerance (ppm)	Recommended Tolerance (ppm)	Comments;

Correct Commodity Definition

40 CFR §180.464(a)

Hop, dried cones	0.05	0.05	Adequate hops residue data are available for
a national registration.

Radish, tops	0.01	0.01	Adequate radish residue data are available.

Radish, roots	0.01	0.01

	Rutabaga, roots	0.01	0.01	The available turnip residue data will
support the equivalent tolerances on rutabaga roots and tops.

Rutabaga, tops	0.1	0.1

	Turnip, greens	0.1	0.1	Adequate residue data are available on turnip
roots and tops.

Turnip, roots	0.01	0.01

	Turnip, tops	0.1	0.1

	40 CFR §180.464(c)

Pumpkin	0.01	0.01	Adequate winter squash residue data are available to
support regionally restricted tolerances on both Pumpkin and Squash,
winter

Winter squash	0.01	0.01

	

References

Subject:	The Metabolism Committee Meeting Held on November 3, 1992. 
Plant and Animal Metabolism of SAN-582H

From:		M. Flood

To:		The Metabolism Committee

Dated:		10/NOV/1992

MRIDs:	None

DP Num:	184986

Subject:	Revised Labels for SAN-582H.  Submission Dated 24/NOV/1992.

From:		M. Flood

To:		C. Giles-Parker and J. Stone

Dated:		07/APR/1993

MRIDs:	None

Subject:	The Metabolism Committee Meeting Held on December 1, 1993. 
Dimethenamid Plant Metabolism and DRES Analysis

From:		M. Bradley

To:		The Metabolism Committee

Dated:		08/DEC/1993

MRIDs:	None

DP Num:	288341

Subject:	Dimethenamid DER Sugar Beet Metabolism Study

From:		D. Dotson

To:		

Dated:		14/APR/2004

MRIDs:	45189703

DP Num:	304790

Subject:	Dimethenamid/Dimethenamid-P.  Human Health Risk Assessment

From:		R. Griffin, J. Facey, and D. Anderson

To:		J. Tompkins

Dated:		12/AUG/2004

MRIDs:	None

  SEQ CHAPTER \h \r 1 Attachments:  

I. International Residue Limit Status sheet

II. Dietary Burden with comments

III. MRL Calculator – Turnip Tops

Attachment I:

INTERNATIONAL
RESI啄⁅䥌䥍⁔呓呁单܇桃浥捩污丠浡㩥†ⴲ档潬潲中⠭
ⰲⴴ楤敭桴汹㌭琭楨湥汹⴩ⵎ⡛匱⴩ⴲ敭桴硯⵹ⴱ敭桴
汹瑥票嵬愠散慴業敤䌇浯潭⁮慎敭ഺ楄敭桴湥浡摩⠠〵
㔺ⰰ删愠摮匠阠獩浯牥⥳䐍浩瑥敨慮業ⵤ⁐㤨㨰〱‬㩓
⁒獩浯牥爠瑡潩ܩ⁘牐灯獯摥琠汯牥湡散

⁯ Reevaluated tolerance

⁯ Other	Date: 01/AUG/2007

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

⁯ No Codex proposal step 6 or above

√No  Codex proposal step 6 or above for the crops requested	Petition
Number:  PP#6E7152

DP Num:  341886

Other Identifier:  

Residue definition (step 8/CXL):

Dimethenamid –P and its enantiomer..  The definition applies to
residues arising from the use of either dimethenamid-p or dimethenamid. 
	Reviewer/Branch:  D. Rate / ARIA/RIMUERB

	Residue definition:  dimethenamid,
1(R,S)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-dimethylthien-3-yl)
-acetamide, applied as either the 90:10 or 50:50 S:R isomers  SEQ
CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 

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

Hop, dried cones	0.05

Pumpkin	0.01

Radish, tops	0.01

Radish, roots	0.01

Rutabaga, roots	0.01

Rutabaga, tops	0.1

Squash, winter	0.01

Turnip, roots	0.01

Turnip, tops	0.1

	Limits for Canada	Limits for Mexico

      No Limits

√   No Limits for the crops requested	   No Limits

√   No Limits for the crops requested

Residue definition 
2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)
acetamide	Residue definition:  dimethenamid

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

	Notes/Special Instructions:  

S.Funk, 08/01/2007.

Attachment II:

Dietary Burden:

File:  Dimethenamid-P dietary burden.revised.js.bs.082308.doc

The dietary burden associated with the proposed new uses and use changes
are summarized in the Table 5.  They were provided by Jerry Stokes of
HED by e-mail (J. Stokes to D. Rate, 23/AUG/2007). 

The following comments are included to help explain why and how
commodities were utilized in the preparation of the MDB.

Comments:

Residues on grass commodities are from treatment of grass grown for
seed.  In these operations, mainly confined to WA, OR, and ID, the cash
crop is the seed.  The major commodity is grass straw that is harvested
at time of seed collection.   The only grass hay available is from fall
regrowth, but regrowth usually occurs to a limited extent.  The small
amount of grass hay that is available is normally grazed by mature beef
cows (best suited for dry cows) and younger beef cattle, or cut and fed
as green chop.  Grass hay is not available to finishing feedlot beef. 
Likewise it is not available to mature dairy cows.  The straw, however
can be fed to feedlot beef and possibly to dairy (although potentially
high pesticide residues ending up in milk may preclude use for dairy).  

The requested tolerance for turnips involves only the varieties grown
for leafy greens.  The varieties grown for livestock feeding are not
included.  Therefore, turnips tops and roots are not considered in the
dietary burdens for cattle.  

Field corn forage/silage is used instead of sweet corn cannery waste.  
Cannery waste is a local and seasonal byproduct and, although it may be
fed mainly to local dairy herds, any residues from cannery waste is far
outweighed by the vast amount of field corn forage/silage fed to dairy
cows on a daily basis.  

Grain from both field corn and grain sorghum are fed to all livestock.  
In addition, milled byproducts from field corn processing are fed to all
livestock.

Although peanut meal can be fed to all livestock, because of its
tendency to become rancid shortly after production, it is normally used
in the peanut growing/processing areas.  This limits the feeding of the
peanut meal in high density poultry and swine production areas.  Soybean
meal and seeds are the most common protein source for livestock. Others
used are cottonseed, canola, safflower, and sunflower meals.  
Production volumes for peanut meal are below any of the feedstuffs
listed above.

Sugarbeet dried pulp and sugarbeet molasses are added to the proposed
cattle rations because these two occur as regular feedstuffs in many
beef and dairy all across the nation.

  

Attachment III:

MRL Calculator:

The Agency’s Guidance for Setting Pesticide Tolerances Based on Field
Trial Data was utilized for determining appropriate tolerance levels on
turnip, tops, as less than 20% of the residue values were above the LOQ
in/on turnip, tops.  However, the tolerance spreadsheet was not used to
calculate tolerances for the remaining commodities, as all residues of
the samples from these crops were <LOQ.

 

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LSOP, the field trial application rates were within 25% of the maximum
application rates, and the PHIs are consistent with the appropriate
stage of maturity and the proposed PHIs for each commodity.  The residue
values used to calculate the alfalfa tolerances are provided in Table
I-1.

The datasets for dimethenamid residues in turnip, tops were entered into
the tolerance spreadsheet.  Visual inspection of the lognormal
probability plot (Figures I-1) indicates that the dataset is not
lognormal, and results from the approximate Shapiro-Francia test
statistic (Figure I-2) confirm this assumption.  Therefore, the CA
method was used to calculate the tolerance.  Although the calculator
says that the tolerance for turnip, tops should be set at 0.09 ppm
because one of the residues exceeded 0.09 ppm, ARIA recommends a
tolerance of 0.1 ppm.

Table I-1:

Residues of Proposed Crop Matrices (ppm)

Radish, Tops	Radish, Roots	Turnip, Tops	Turnip, Roots	Winter Squash
Hops, dried Cones

ND	ND	0.015	ND	ND	ND

ND	ND	0.010	ND	ND	ND

ND	ND	ND	ND	ND	ND

ND	ND	ND	ND	ND	ND

ND	ND	ND	ND	ND	ND

ND	ND	ND	ND	ND	ND

ND	ND	ND	ND

ND	ND	ND	ND

ND	ND	ND	ND

ND	ND	ND	ND

ND	ND	ND	ND

ND	ND	ND	ND

ND	ND

ND	ND

0.093	ND

0.051	ND

ND= Non-Detect.  ND is <0.01 ppm for all commodities except hops, dried
cones.  ND for hops is <0.05 ppm

Figure I-1:  

Figure I-2:

Page   PAGE  1  of   NUMPAGES  20 

Dimethenamid-P	Summary of Analytical Chemistry and Residue Data	DPNum:
341886