![](media/image1.png){width="0.7993055555555556in" height="0.8in"}

**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

**[MEMORANDUM]{.underline}**

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      372743
                                  Number:       

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

  40 CFR 180.   464                             

  Chemical      Chloroacetamide                 
  Class:        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)

Number range CHAPTERThis 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)acetamide,
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

Number range CHAPTERThe 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. Number range CHAPTERConsidering 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.

Number range CHAPTERAn 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, Number range CHAPTERresidues of dimethenamid
were determined using a gas chromatography with a mass selective
detector (GC/MSD) Number range CHAPTERmethod. 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.

Number range CHAPTER**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.

[]{.mark}

Permanent tolerances are established for residues of dimethenamid,
(*RS*)-2-chloro-*N*-\[(1-methyl-2-methoxy)ethyl\]-*N*-(2,4-dimethylthien-3-yl)acetamide,
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.

[]{.mark}

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            ![](media/image2.wmf){width="2.020138888888889in" height="1.28125in"}

  Common name         Number range CHAPTERDimethenamid-P (or S-Dimethenamid); 90:10, S:R isomer ratio

  Company             BAS 656H; SAN 1289
  experimental name   

  IUPAC name          Number range
                      CHAPTER(*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*-\[(1*S*)-2-methoxy-1-methylethyl\]
                      acetamide

  CAS registry number 163515-14-8

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

  ------------------------------------------------------------------------
  **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,    No Dissociation                 
  pK~a~                                                     

  Octanol/water partition   77.6 and 1.89 (P~OW~ and log    
  coefficient               P~OW~)                          

  UV/visible absorption     ε = 7560; 33 nm                 
  spectrum                                                  
  ------------------------------------------------------------------------

**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.

[]{.mark}

+-----------------+--------+-----+------+--------+------+-------------+
| **Table 3.      |        |     |      |        |      |             |
| Summary of      |        |     |      |        |      |             |
| Directions for  |        |     |      |        |      |             |
| Use of          |        |     |      |        |      |             |
| Di              |        |     |      |        |      |             |
| methenamid-P.** |        |     |      |        |      |             |
+=================+========+=====+======+========+======+=============+
| Applic. Timing, | Formu  | A   | Max. | Max.   | PHI  | Use         |
| Type, and       | lation | ppl | No.  | Se     |      | Directions  |
| Equip. ^1^      |        | ic. | App  | asonal | (d   | and         |
|                 | \[EPA  | Ra  | lic. | A      | ays) | Limitations |
|                 | Reg.   | tes | per  | pplic. |      | ^2^         |
|                 | No.\]  |     | Se   | Rate   |      |             |
|                 |        | (lb | ason |        |      |             |
|                 |        | ai  |      | (lb    |      |             |
|                 |        | /A) |      | ai/A)  |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| **Hops (only in |        |     |      |        |      |             |
| ID, OR and      |        |     |      |        |      |             |
| WA)**           |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| Directed or     | 6.0    | 0.5 | 1    | 0.98   | 60   | This use is |
| banded          | lb/gal | 6-0 |      |        |      | restricted  |
| post-emergence  | EC     | .98 |      |        |      | to the      |
| application     |        |     |      |        |      | states of   |
| from vegetative | \[7969 |     |      |        |      | ID, OR and  |
| to early bloom  | -156\] |     |      |        |      | WA.         |
| stages, using   |        |     |      |        |      |             |
| ground          |        |     |      |        |      |             |
| equipment       |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| **Radish**      |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| Broadcast       | 6.0    | 0.5 | 1    | 0.98   | 21   |             |
| post-emergence  | lb/gal | 6-0 |      |        |      |             |
| application     | EC     | .98 |      |        |      |             |
| when plants are |        |     |      |        |      |             |
| at 2- to 4-leaf | \[7969 |     |      |        |      |             |
| stage, using    | -156\] |     |      |        |      |             |
| ground          |        |     |      |        |      |             |
| equipment       |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| **Turnip and    |        |     |      |        |      |             |
| Rutabaga**      |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| Broadcast       | 6.0    | 0.5 | 1    | 0.98   | tops |             |
| post-emergence  | lb/gal | 6-0 |      |        | --   |             |
| application     | EC     | .98 |      |        | 14   |             |
| when plants are |        |     |      |        |      |             |
| at 2- to 8-leaf | \[7969 |     |      |        | roo  |             |
| stage, using    | -156\] |     |      |        | ts - |             |
| ground          |        |     |      |        | 40   |             |
| equipment       |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| **Winter Squash |        |     |      |        |      |             |
| and Pumpkins    |        |     |      |        |      |             |
| (only in OR and |        |     |      |        |      |             |
| WA)**           |        |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+
| Broadcast       | 6.0    | 0.5 | 1    | 0.98   | 90   | This use is |
| preemergence    | lb/gal | 6-0 |      |        |      | restricted  |
| application     | EC     | .98 |      |        |      | to the      |
| using ground    |        |     |      |        |      | states of   |
| equipment       | \[7969 |     |      |        |      | OR and WA   |
|                 | -156\] |     |      |        |      |             |
+-----------------+--------+-----+------+--------+------+-------------+

^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:]{.underline}* 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

Number range CHAPTERThe 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
\[3-^14^C-thienyl\]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 ^14^C-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 \[^14^C\]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 \[^14^C\]dimethenamid
sugar beet metabolism study is adequate. Parent, dimethenamid, was
extensively metabolized and not detected in sugar beet roots or tops.

*[Conclusions:]{.underline}* 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. Number range
CHAPTERIn the ruminant metabolism study, a dairy goat was dosed orally
for 4 days with \[^14^C\]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. \[^14^C\]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 \[^14^C\]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 ^14^C-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:]{.underline}* 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]{.underline}

Number range CHAPTERAn 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.

[]{.mark}

[Data collection methods]{.underline}

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 (Number range CHAPTERAM-0884-0193-1). For this
method, Number range CHAPTERresidues are extracted with methanol:water
(95:5, v:v), purified using a C~18~ 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 C~18~ 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.

[]{.mark}

In the hops field trials, Number range CHAPTERresidues of dimethenamid
were determined using a Number range CHAPTERGC/MSD method which was
derived from the tolerance enforcement method. For this method, Number
range CHAPTERresidues 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 NH~2~ 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**

Number range CHAPTERThe 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.

The data indicate that dimethenamid is stable in frozen 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:]{.underline}* 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    | Actual Storage     | Interval of        |
|             | T          | Duration           | Demonstrated       |
|             | emperature |                    | Storage Stability  |
|             | (°C)       | (months)           | (months)           |
+-------------+------------+--------------------+--------------------+
| Turnip tops | -20        | 13.5-20            | 24                 |
+-------------+------------+--------------------+--------------------+
| Turnip      |            | 13.3-20            | 24                 |
| roots       |            |                    |                    |
+-------------+------------+--------------------+--------------------+
| Radish tops | -20        | 19.4-20.3          | 20.7               |
+-------------+------------+--------------------+--------------------+
| Radish      |            | 18.9-20.3          | 20.5               |
| roots       |            |                    |                    |
+-------------+------------+--------------------+--------------------+
| Winter      | -18        | 1-2                | 2.2                |
| squash      |            |                    |                    |
+-------------+------------+--------------------+--------------------+
| Hops, dried | -18        | 12.2-12.7          | 11.5               |
| cones       |            |                    |                    |
+-------------+------------+--------------------+--------------------+

Number range CHAPTER**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).

[]{.mark}

+---------------------+-------+-----+-------+-----------+------------+
| **Table 5.          |       |     |       |           |            |
| Calculation of      |       |     |       |           |            |
| Maximum Dietary     |       |     |       |           |            |
| Burdens of          |       |     |       |           |            |
| Livestock for       |       |     |       |           |            |
| Dimethenamid        |       |     |       |           |            |
| Residues. (e-mail:  |       |     |       |           |            |
| J. Stokes to D.     |       |     |       |           |            |
| Rate,               |       |     |       |           |            |
| 23/AUG/2007)**      |       |     |       |           |            |
+=====================+=======+=====+=======+===========+============+
| Feedstuff           | Di    | \%  | \%    | Re        | Dietary    |
|                     | etary | Dry | Diet  | commended | Co         |
|                     | ^1^   | Mat | ^2^   | Tolerance | ntribution |
|                     | Comp  | ter |       | (ppm)     | (ppm) ^3^  |
|                     | onent | ^2^ |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| **Beef Cattle R:    |       |     |       |           |            |
| 15%; CC: 75 %; PC:  |       |     |       |           |            |
| 10%**               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| grass, straw        | R     | 88  | 10    | 0.01      | 0.0011     |
+---------------------+-------+-----+-------+-----------+------------+
| beet, sugar, dried  | R     | 88  | 5     | 0.01      | 0.0006     |
| pulp                |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| corn, field, grain/ | CC    | 85  | 70    | 0.01      | 0.0082     |
| milled bypdts/      |       |     |       |           |            |
|                     |       |     |       |           |            |
| sorghum, grain,     |       |     |       |           |            |
| grain               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| beet, sugar,        | CC    | 75  | 5     | 0.01      | 0.0007     |
| molasses            |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| soybean seeds       | PC    | 92  | 10    | 0.01      | 0.0011     |
+---------------------+-------+-----+-------+-----------+------------+
| TOTAL BURDEN        |       |     | **    |           | **0.017**  |
|                     |       |     | 100** |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| **Dairy Cattle R:   |       |     |       |           |            |
| 45%; CC: 45 %; PC:  |       |     |       |           |            |
| 10%**               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| grass, straw        | R     | 88  | 10    | 0.01      | 0.0011     |
+---------------------+-------+-----+-------+-----------+------------+
| corn, field,        | R     | 40  | 30    | 0.01      | 0.0075     |
| forage/silage       |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| beet, sugar, dried  | R     | 88  | 5     | 0.01      | 0.0006     |
| pulp                |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| corn, field, grain/ | CC    | 85  | 40    | 0.01      | 0.0047     |
| milled bypdts/      |       |     |       |           |            |
|                     |       |     |       |           |            |
| sorghum, grain,     |       |     |       |           |            |
| grain               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| beet, sugar,        | CC    | 75  | 5     | 0.01      | 0.0006     |
| molasses            |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| soybean seeds       | PC    | 92  | 10    | 0.01      | 0.0011     |
+---------------------+-------+-----+-------+-----------+------------+
| TOTAL BURDEN        |       |     | **    |           | **0.016**  |
|                     |       |     | 100** |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| **Poultry CC: 75 %; |       |     |       |           |            |
| PC: 25 %**          |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| corn, field, grain/ | CC    | \-- | 75    | 0.01      | 0.0075     |
| milled bypdts/      |       |     |       |           |            |
|                     |       |     |       |           |            |
| sorghum, grain,     |       |     |       |           |            |
| grain               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| soybean             | PC    |     | 25    | 0.01      | 0.0025     |
| seeds/peanut meal   |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| TOTAL BURDEN        |       |     | **    |           | **0.010**  |
|                     |       |     | 100** |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| **Swine CC: 85 %;   |       |     |       |           |            |
| PC: 15 %**          |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| corn, field, grain/ | CC    | 85  | 85    | 0.01      | 0.0085     |
| milled bypdts/      |       |     |       |           |            |
|                     |       |     |       |           |            |
| sorghum, grain,     |       |     |       |           |            |
| grain               |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| soybean             | PC    |     | 15    | 0.01      | 0.0015     |
| seeds/peanut meal   |       |     |       |           |            |
+---------------------+-------+-----+-------+-----------+------------+
| TOTAL BURDEN        |       |     | **    |           | **0.010**  |
|                     |       |     | 100** |           |            |
+---------------------+-------+-----+-------+-----------+------------+

^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 Number range
CHAPTERextensive 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. Number range CHAPTERThe 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       PHI       Residue                                               
                   Applic.     (days)    Levels                                                
                   Rate (lb              (ppm) ^1^                                             
                   ai/A)                                                                       

                                         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      0.97-1.02   60-61     6         \<0.01   \<0.01   \<0.01   0.01     0.01    \--
  cones                                                                                        
  ----------------------------------------------------------------------------------------------------

^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.

[]{.mark}

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%.

[]{.mark}

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.

[]{.mark}

**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.

[]{.mark}

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.

Number range CHAPTER**860.1650 Submittal of Analytical Reference
Standards**

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

Number range CHAPTER**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, Number range
CHAPTERrequirements 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)acetamide,
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. []{.mark}

[]{.mark}

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     | Recommended | Comments;             |
|                 | Tolerance    | Tolerance   |                       |
|                 | (ppm)        | (ppm)       | *Correct Commodity    |
|                 |              |             | Definition*           |
+-----------------+--------------+-------------+-----------------------+
| **40 CFR        |              |             |                       |
| §180.464(a)**   |              |             |                       |
+-----------------+--------------+-------------+-----------------------+
| Hop, dried      | 0.05         | 0.05        | Adequate hops residue |
| cones           |              |             | 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 P*umpkin* and |
|                 |              |             | *Squash, winter*      |
+-----------------+--------------+-------------+-----------------------+
| Winter squash   | 0.01         | 0.01        |                       |
+-----------------+--------------+-------------+-----------------------+

**References**

[]{.mark}

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

[]{.mark}

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

[]{.mark}

DP Num: 288341

Subject: Dimethenamid DER Sugar Beet Metabolism Study

From: D. Dotson

To:

Dated: 14/APR/2004

MRIDs: 45189703

[]{.mark}

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

Number range CHAPTERAttachments:

I. International Residue Limit Status sheet

II\. Dietary Burden with comments

III\. MRL Calculator -- Turnip Tops

Attachment I:

+-----------------+----------------+-------------------+-------------+
| INTERNATIONAL   |                |                   |             |
| RESIDUE LIMIT   |                |                   |             |
| STATUS          |                |                   |             |
+=================+================+===================+=============+
| Chemical Name:  | Common Name:   | X Proposed        | Date:       |
| 2-chloro-*N*-(  |                | tolerance         | 01/AUG/2007 |
| 2,4-dimethyl-3- | Dimethenamid   |                   |             |
| thienyl)-*N*-\[ | (50:50, R and  | ⁯Reevaluated       |             |
| (1S)-2-methoxy- | S --isomers)   | tolerance         |             |
| 1-methylethyl\] |                |                   |             |
| acetamide       | Dimethenamid-P | ⁯Other             |             |
|                 | (90:10, S:R    |                   |             |
|                 | isomer ratio)  |                   |             |
+-----------------+----------------+-------------------+-------------+
| Codex Status    |                | U. S. Tolerances  |             |
| (Maximum        |                |                   |             |
| Residue Limits) |                |                   |             |
+-----------------+----------------+-------------------+-------------+
| ⁯No Codex        |                | Petition Number:  |             |
| proposal step 6 |                | PP#6E7152         |             |
| or above        |                |                   |             |
|                 |                | DP Num: 341886    |             |
| √No Codex       |                |                   |             |
| proposal step 6 |                | Other Identifier: |             |
| or above for    |                |                   |             |
| the crops       |                |                   |             |
| requested       |                |                   |             |
+-----------------+----------------+-------------------+-------------+
| Residue         |                | Reviewer/Branch:  |             |
| definition      |                | D. Rate /         |             |
| (step 8/CXL):   |                | ARIA/RIMUERB      |             |
|                 |                |                   |             |
| Dimethenamid    |                |                   |             |
| --P and its     |                |                   |             |
| enantiomer..    |                |                   |             |
| The definition  |                |                   |             |
| applies to      |                |                   |             |
| residues        |                |                   |             |
| arising from    |                |                   |             |
| the use of      |                |                   |             |
| either          |                |                   |             |
| dimethenamid-p  |                |                   |             |
| or              |                |                   |             |
| dimethenamid.   |                |                   |             |
+-----------------+----------------+-------------------+-------------+
|                 |                | Residue           |             |
|                 |                | definition:       |             |
|                 |                | dimethenamid,     |             |
|                 |                | 1(R,              |             |
|                 |                | S)-2-chloro-*N*-\ |             |
|                 |                | [(1-methyl-2-meth |             |
|                 |                | oxy)ethyl\]-*N*-( |             |
|                 |                | 2,4-dimethylthien |             |
|                 |                | -3-yl)-acetamide, |             |
|                 |                | applied as either |             |
|                 |                | the 90:10 or      |             |
|                 |                | 50:50 S:R         |             |
|                 |                | isomersNumber     |             |
|                 |                | range             |             |
|                 |                | CHAPTERNumber     |             |
|                 |                | range CHAPTER     |             |
+-----------------+----------------+-------------------+-------------+
| 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      |                | Limits for Mexico |             |
| Canada          |                |                   |             |
+-----------------+----------------+-------------------+-------------+
|  No Limits     |                |  No Limits       |             |
|                 |                |                   |             |
| √ No Limits for |                | √ No Limits for   |             |
| the crops       |                | the crops         |             |
| requested       |                | requested         |             |
+-----------------+----------------+-------------------+-------------+
| Residue         |                | Residue           |             |
| definition      |                | definition:       |             |
| 2-chlor         |                | dimethenamid      |             |
| o-*N*-(2,4-dime |                |                   |             |
| thyl-3-thienyl) |                |                   |             |
| -*N*-(2-methoxy |                |                   |             |
| -1-methylethyl) |                |                   |             |
| acetamide       |                |                   |             |
+-----------------+----------------+-------------------+-------------+
| 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:

1.  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).

2.  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.

3.  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.

4.  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.

5.  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.

6.  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.

The datasets used to establish tolerances for dimethenamid residues on
turnip, tops consisted of field trial data representing applications of
the appropriate formulations at \~1x proposed use rates. As specified by
the *Guidance for Setting Pesticide Tolerances Based on Field Trial
Data* SOP, 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,     Radish,     Turnip,     Turnip,     Winter       Hops, dried
  Tops        Roots       Tops        Roots       Squash       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:

![](media/image3.wmf){width="4.4743055555555555in"
height="2.6840277777777777in"}

Figure I-2:

![](media/image4.png){width="4.345833333333333in"
height="3.5597222222222222in"}