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**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**WASHINGTON D.C., 20460**

**OFFICE OF**

**PREVENTION, PESTICIDES AND**

**TOXIC SUBSTANCES**

PC Code: 268800

DP Barcode: D328740

April 26, 2006

**[MEMORANDUM]{.underline}**

SUBJECT: Drinking Water Assessment for the IR-4 registration for the new
uses of dimethomorph for use on brassica head and stem subgroup 5A.

TO: Barbara Madden, Risk Manager Reviewer

Daniel Rosenblatt, Risk Manager

Registration Division (7505P)

AND: John Redden, Team Leader

Technical Review Branch

Registration Division (7505P)

FROM: José Luis Meléndez, Chemist

Environmental Risk Branch V

Environmental Fate and Effects Division

THROUGH: Karen Whitby, Acting Branch Chief

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)

This memo presents the Tier I Estimated Surface Drinking Water
Concentrations and Estimated Ground Water Concentrations (EDWCs) for
Dimethomorph, calculated using the Tier I aquatic models FIRST and
SCI-GROW, respectively, for use in the human health risk assessment.

The Estimated Drinking Water Concentrations (EDWCs) for dimethomorph
were calculated based on a maximum application rate of 1.4 lb
a.i./A/season. The acute drinking water concentration in surface water
is 81.1 ppb of dimethomorph, based on applications of the chemical to
broccoli (representative of brassica head and stem). The cancer/chronic
drinking water concentration is 24.7 ppb (based on applications to
broccoli, highest application rate). The SCI-GROW generated EDWC is
0.264 ppb of dimethomorph, which is recommended for use, both for acute
and chronic exposures. Table I provides a summary of the Tier I modeled
drinking water concentrations. Should there be a need for additional
refinements, the EFED can perform a Tier II aquatic assessment, for
surface waters.

**[EXECUTIVE SUMMARY]{.underline}**

Dimethomorph's full chemical name is (E,Z)
4-\[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)-1-oxo-2-propenyl\]
morpholine, CAS# 110488-70-5, and PC code 268800. The CAS# for the E
diatereoisomer is 113210-97-2. The CAS# for the Z diastereoisomer is
113210-98-3. Its' structure has three rings, two of which are
phenyl-type rings (refer to structure in Appendix D).

Dimethomorph is a systemic fungicide which protects plants from molds,
as well as killing molds on plants and preventing their spread. It is a
cinnamic acid derivative and a member of the morpholine chemical family.
It's mode of action is the inhibition of sterol (ergosterol) synthesis.
It is a mixture of two isomers (E and Z) but only the Z isomer has
fungicidal activity. It is available as a wettable powder. The use
proposed in this IR4 (Interregional Research Project No. 4) is brassica
head stem and stem subgroup 5A. It is to be applied as a foliar spray.

This is a Tier I screening drinking waters assessment using Tier I
aquatic models SCI-GROW and FIRST, and maximum application rates for
dimethomorph, with minimum interval between applications. It was found
that the worst case scenario was brassica head and steam group
(represented by broccoli) for dimethomorph, with the highest seasonal
application rate, and the highest PCA. There were no major degradates
observed in the aerobic soil metabolism study; therefore, no degradates
were modeled in this exercise. Should additional refinements of the
assessment are needed, the EFED can schedule a higher Tier analysis.

There are uncertainties in this assessment related to the mobility
studies. Three studies are available, but two of them were conducted
with foreign soils. They indicated more mobility than the study
conducted with domestic soils. Furthermore, the metabolism studies
showed high levels of nonextractable residues. At this time, it appears
that there are no terrestrial field dissipation studies, to confirm what
happened in the laboratory.

The proposed use involved in this action is for the following IR4
tolerance petition: brassica head and stem, subgroup 5A. It includes
broccoli, Chinese broccoli, Brussels sprouts, cabbage, Chinese cabbage
{napa}, Chinese mustard, cauliflower, cavalo broccoli and hohlrabi
(refer to highlighted section of Table 2 for additional details).

**Table 1. Maximum Tier I Estimated Drinking Water Concentrations
(EDWCs) for drinking water risk assessment based on aerial application
of dimethomorph.**

+---------------+-------------------------+---------------+----------+
| **DRINKING    | **USE (rate modeled)**  | **MAXIMUM     |          |
| WATER SOURCE  |                         | ESTIMATED     |          |
| (MODEL        |                         | DRINKING      |          |
| USED)**       |                         | WATER         |          |
|               |                         | CONCENTRATION |          |
|               |                         | (EDWC)        |          |
|               |                         | (ppb)**       |          |
+---------------+-------------------------+---------------+----------+
| Groundwater   | Broccoli (1.4 lb        | Acute and     | 0.264    |
| (SCIGROW)     | a.i./A)                 | chronic       |          |
+---------------+-------------------------+---------------+----------+
| Surface water | Broccoli (1.4 lb        | Acute         | 81.1     |
|               | a.i./A)                 |               |          |
| (FIRST)       |                         |               |          |
+---------------+-------------------------+---------------+----------+
|               | Broccoli (1.4 lb        | Chronic       | 24.7     |
|               | a.i./A)                 |               |          |
+---------------+-------------------------+---------------+----------+

**[PROBLEM FORMULATION]{.underline}**

*This is a Tier I drinking water assessment that uses modeling to
estimate the groundwater and surface water concentrations in drinking
water source (pre-treatment), resulting from pesticide use on sites that
are highly vulnerable. This initial tier screens out chemicals with low
potential riskand allows OPP to focus resources on more refined risk
assessments for chemicals which potentially present more significant
risks. This drinking water assessment will report potential exposure
concentrations for the human health dietary risk assessment and provide
a clear and transparent description of how those concentrations were
determined.*

**[ANALYSIS]{.underline}**

**Use Characterization**

Table 2 is a summary of all agricultural use patterns for dimethomorph.
The highlighted use is the proposed new one under IR4 petition. The use
information was obtained from the current label for ACROBAT® 50WP
Fungicide, and the proposed label for the same product.

**Table 2. Summary use information for dimethomorph, based on ACROBAT®
50WP Fungicide label (EPA Reg. No. 241-410), containing 50.0% a.i., and
50.0% inerts.Number range CHAPTER**

  ---------------------------------------------------------------------------------------------------
  **USE**             **SINGLE    **NO. OF  **SEASONAL   **INTERVAL   **APP.        **INCORPORATION
                      APP RATE    APPS.**   APP. RATE    BETWEEN      METHOD**      DEPTH (inches)**
                      (lb                   (lb          APPS.                      
                      a.i./A)**             a.i./A)**    (days)**                   
  ------------------- ----------- --------- ------------ ------------ ------------- -----------------
  Bulb Vegetable      0.2         5         1.0          5            Ground,       0
  (Garlic, leek,                                                      aerial,       
  onion, shallot)                                                     chemigation   

  Cucurbit vegetable  0.2         5         1.0          5            Ground,       0
  (chayote,                                                           aerial,       
  cantaloupe, Chinese                                                 chemigation   
  waxgourd, citron                                                                  
  melon, cucumber,                                                                  
  gherkin, edible                                                                   
  gourd, *momordica                                                                 
  spp.*, muskmelon,                                                                 
  pumpkin, squash,                                                                  
  winter watermelon,                                                                
  summer squash)                                                                    

  Fruiting vegetable  0.2         5         1.0          5            Ground,       0
  group (except                                                       aerial,       
  tomato) (eggplant,                                                  chemigation   
  ground cherry,                                                                    
  pepino, pepper,                                                                   
  tomatillo)                                                                        

  Leafy brassica      0.2         5         1.0          7            Ground,       0
  greens                                                              aerial,       
                                                                      chemigation   

  Hops                0.2         3         0.6          10           Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Lettuce (head and   0.2         5         1.0          5            Ground,       0
  leaf)                                                               aerial,       
                                                                      chemigation   

  Potato              0.2         5         1.0          5            Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Taro                0.2         5         1.0          7            Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Tobacco             0.25        4         1.0          5            Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Tomato-Non-staked   0.2         5         1.0          5            Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Tomato-Staked       0.2         5         1.0          5            Ground,       0
                                                                      aerial,       
                                                                      chemigation   

  Brassica, head and  0.2         7         1.4          7            Ground,       0
  stem, subgroup 5A                                                   aerial,       
  (broccoli, Brussels                                                 chemigation   
  sprouts, cabbage,                                                                 
  Chinese cabbage                                                                   
  {napa}, Chinese                                                                   
  mustard,                                                                          
  cauliflower, cavalo                                                               
  broccolo, hohlrabi                                                                
  ---------------------------------------------------------------------------------------------------

ACROBAT® 50WP Fungicide is a wettable powder. It may be applied by
ground methods, chemigation, or aerially. There are no buffer zone
restrictions in this label. Usually the maximum seasonal application
rate is 1.0 lb a.i./A. For the proposed new use (IR4 petition), the
maximum seasonal application rate is 1.4 lb a.i./A. Thorough coverage is
required to obtain maximum benefit and minimize the potential for
resistance.

The use pattern selected for drinking water modeling was the proposed
new use (brassica head and stem), and the representative crop was
broccoli. It was selected because it involves the maximum application
rate, and hence, the maximum exposure. Furthermore, it has the maximum
PCA (the default of 0.87).

**Fate and Transport Characterization**

Table 3 provides a detailed summary of physical/chemical and
environmental fate/transport properties of dimethomorph, including
measured parameters, values, data sources, and comments.

**Table 3. Summary of physical/chemical and environmental fate and
transport properties of dimethomorph.Number range CHAPTER**

+-------------------+-------------------+----------+-----------------+
| **PARAMETER**     | **VALUES (s)      | **       | **COMMENT**     |
|                   | (units)**         | SOURCE** |                 |
+===================+===================+==========+=================+
| Chemical Name     | 4-\[3-(           | --       | CAS name        |
|                   | 4-chlorophenyl)-3 |          |                 |
|                   | -(3,4-dimethoxyph |          | IUPAC name      |
|                   | enyl)-1-oxo-2-pro |          |                 |
|                   | penyl\]morpholine |          |                 |
|                   |                   |          |                 |
|                   | (*EZ*)-4-\[3      |          |                 |
|                   | -(4-chlorophenyl) |          |                 |
|                   | -3-(3,4-dimethoxy |          |                 |
|                   | phenyl)acryloyl\] |          |                 |
|                   | morpholine        |          |                 |
+-------------------+-------------------+----------+-----------------+
| Molecular Weight  | 387.86            | --       | --              |
+-------------------+-------------------+----------+-----------------+
| Solubility (20ºC) | E isomer: at pH 5 | \--      | --              |
|                   | 13 mg/L, at pH 7  |          |                 |
|                   | 12 mg/L, at pH 9  |          |                 |
|                   | 11 mg/L           |          |                 |
|                   |                   |          |                 |
|                   | Z isomer: at pH 5 |          |                 |
|                   | 6 mg/L, at pH 7 6 |          |                 |
|                   | mg/L, at pH 9 5   |          |                 |
|                   | mg/L              |          |                 |
+-------------------+-------------------+----------+-----------------+
| Melting Point     | 127-148ºC         | Tomlin   | Z               |
|                   |                   | (ed.)    | isom            |
|                   |                   |          | er169.2-170.2ºC |
|                   |                   |          | E               |
|                   |                   |          | isom            |
|                   |                   |          | er135.7-137.5ºC |
+-------------------+-------------------+----------+-----------------+
| Bulk Density      | 1318 Kg/m^3^      | Tomlin   | \--             |
|                   |                   | (ed.)    |                 |
+-------------------+-------------------+----------+-----------------+
| Solubility        | Acetone: 15 (Z),  | Tomlin   | \_              |
| (20-23ºC) (g/L)   | 88 (E);           | (ed.)    |                 |
|                   | cyclohexanone     |          |                 |
|                   | 27(Z);            |          |                 |
|                   | dichloromethane   |          |                 |
|                   | 315 (Z);          |          |                 |
|                   | dimethylformamide |          |                 |
|                   | 40 (Z), 272 (E);  |          |                 |
|                   | hexane 0.02 (Z),  |          |                 |
|                   | 0.04 (E);         |          |                 |
|                   | methanol 7 (Z);   |          |                 |
|                   | toluene 7 (Z)     |          |                 |
+-------------------+-------------------+----------+-----------------+
| Vapor Pressure    | E isomer 7.3 x    | Tomlin   | --              |
| (20ºC)            | 10^-9^ mmHg       | (ed.)    |                 |
|                   |                   |          |                 |
|                   | Z isomer 7.5 x    |          |                 |
|                   | 10^-9^ mmHg       |          |                 |
+-------------------+-------------------+----------+-----------------+
| Henry's Law       | 2.06-2.13 x       | \--      | Estimated from  |
| Constant          | 10^-10^           |          | vapor pressure  |
|                   | atm-m^3^/mole     |          | and water       |
|                   |                   |          | solubility.     |
+-------------------+-------------------+----------+-----------------+
| pKa (20ºC)        | Not available     | \--      | --              |
+-------------------+-------------------+----------+-----------------+
| Octanol-Water     | 479               | Tomlin   | log K~OW~ =     |
| Partition         |                   | (ed.)    | 2.68            |
| Coefficient       |                   |          |                 |
|                   |                   |          |                 |
| Kow, at 20º       |                   |          |                 |
+-------------------+-------------------+----------+-----------------+
| Hydrolysis        | stable            | MRID:    | Stable at all   |
| Half-life         |                   | 4        | pHs for a       |
|                   |                   | 3917226. | period of 10    |
| (pH 4, 7, 9 \[70  |                   |          | weeks.          |
| or 90ºC\])        |                   |          |                 |
+-------------------+-------------------+----------+-----------------+
| Aquous Photolysis | t~1/2~ = 50-56    | MRID:    | Value           |
| Half- life        | days              | 4        | corresponds to  |
|                   |                   | 3917227. | 12 hour         |
| (pH 5)            |                   |          | photocycle in   |
|                   |                   |          | midsummer,      |
|                   |                   |          | uncorrected     |
|                   |                   |          | half-life with  |
|                   |                   |          | continuous      |
|                   |                   |          | irradiation was |
|                   |                   |          | 25-28 days.     |
+-------------------+-------------------+----------+-----------------+
| Soil photolysis   | t~1/2~ = 75 days  | MRID:    | Continuous      |
| half- life        |                   | 4        | irradiation     |
|                   |                   | 3917228. | with a xenon    |
|                   |                   |          | arc lamp.       |
+-------------------+-------------------+----------+-----------------+
| Aerobic Soil      | t~1/2~ = 66 days  | MRID:    | Study yielding  |
| Metabolism        |                   | 4        | a half-life of  |
| Half-life         | t~1/2~ = 117 days | 3917229, | 66 days was     |
|                   |                   | 4        | deemed          |
|                   |                   | 3917230. | supplemental.   |
|                   |                   |          | Both studies    |
|                   |                   |          | were performed  |
|                   |                   |          | with foreign    |
|                   |                   |          | soils (British, |
|                   |                   |          | German).        |
+-------------------+-------------------+----------+-----------------+
| Anaerobic Soil    | DT~50~ \~ 5-10    | MRID     | Supplemental    |
| Metabolism        | days              | 4        | studies; system |
|                   |                   | 3917231, | was dosed with  |
| Half-life         | DT~50~ \< 20 days | 4        | Lucerne meal    |
|                   |                   | 3917232, | when the flasks |
|                   | t~½~ = 26.2 and   | 44780201 | were made       |
|                   | 25.7 days         |          | anaerobic.      |
|                   |                   |          | Other study     |
|                   |                   |          | also            |
|                   |                   |          | supplemental.   |
+-------------------+-------------------+----------+-----------------+
| Anaerobic Aquatic | \<1 day           | MRID:    | Supplemental    |
| Metabolism        |                   | 4        | studies.        |
|                   | \<1 day           | 3917233. |                 |
| Half-life         |                   |          |                 |
+-------------------+-------------------+----------+-----------------+
| Aerobic Aquatic   | Not Available     | NA       | \--             |
| Metabolism        |                   |          |                 |
|                   |                   |          |                 |
| Half-life         |                   |          |                 |
+-------------------+-------------------+----------+-----------------+
| Organic Carbon    | 566, 402, 290,    | MRID:    | Various foreign |
| Partition         | 515, 377, 388,    | 4        | soils, two      |
|                   | 316, 1588, 1158,  | 6235734, | soils tested    |
| Coefficient       | 1485, 787         | 4        | twice (once in  |
| (K~OC~)           | mL/g~OC~          | 3917235, | each study).    |
|                   |                   | 4        | The last four   |
|                   |                   | 4780202. | readings were   |
|                   |                   |          | performed with  |
|                   |                   |          | domestic soils  |
|                   |                   |          | (acceptable).   |
+-------------------+-------------------+----------+-----------------+
| Soil Partition    | 4.47, 11.67,      |          |                 |
| Coefficient       | 2.09, 4.94, 8.51, |          |                 |
| (K~d~)            | 2.72, 3.03, 15.7, |          |                 |
|                   | 10.1, 19.0, 11.9  |          |                 |
|                   |                   |          |                 |
|                   | mL/g              |          |                 |
+-------------------+-------------------+----------+-----------------+
| Terrestrial Field | Not available     | NA       | \--             |
| Dissipation       |                   |          |                 |
|                   |                   |          |                 |
| Half-life         |                   |          |                 |
+-------------------+-------------------+----------+-----------------+

The major routes of dissipation of dimethomorph appear to be metabolism,
which is moderate (66-117 days aerobic and around 26 days anaerobic).
Another possible route of dissipation is leaching, since 5 out of the 11
K~d~ values were less than 5. Based on the FAO mobility classification,
the K~OC~ values range from moderately mobile to slightly mobile.
Dimethomorph can reach adjacent bodies of water via spray drift or
through runoff dissolved in the water or partly adsorbed to eroding
particles depending on the properties of the soil. Dimethomorph has some
potential to be persistent, however there are uncertainties in the
database that do not allow one to reach concrete conclusions.

One aspect of dimethomorph is that the diastereoisomer that is active is
the Z one. In the last anaerobic soil metabolism and in the aqueous
photolysis studies, it was observed that there was conversion of the E
isomer to the Z isomer (the one that is active). This phenomenon could
have an impact in the assessments if the Z isomer is more toxic than the
E isomer.

[]{.mark}

There is also uncertainty with respect to the formation of
transformation products. In the aerobic soil metabolism no major
transformation products were detected but large amounts of unextracted
material were observed. In the last anaerobic soil metabolism study
(supplemental), two transformation products were observed: *p*-desmethyl
dimethomorph and *m*-desmethyl dimethomorph. No information on any other
transformation product could be gathered and no degradation pathway
could be traced for dimethomorph.

There is also uncertainty with respect to two mobility studies that were
deemed supplemental because they were conducted with foreign soils.
These studies yielded smaller K~d~'s and K~OC~'s than the study
conducted with domestic soils.

Dimethomorph is not likely to bioaccumulate substantially in fish or
other aquatic organisms as indicated by its low octanol/water partition
coefficient (479).

[]{.mark}

**Table 4. Summary of degradate formation from degradation of
dimethomorph**

  -----------------------------------------------------------------------------
  **STUDY TYPE**  **SOURCE**    **DEGRADATE and                   
                                MAXIMUM                           
                                CONCENTRATION**                   
  --------------- ------------- ----------------- --------------- -------------
                                *p*-desmethyl     *m*-desmethyl   **DEG3 (%
                                dimethomorph **(% dimethomorph    applied)**
                                applied)**        **(% applied)** 

  Hydrolysis      MRID:         \--               --              --
                  43917226.                                       

  Aqueous         MRID:         \--               \--             --
  Photolysis      43917227.                                       

  Soil Photolysis MRID:         \--               \--             --
                  43917228.                                       

  Aerobic Soil    MRID:         \--               --              --
  Metabolism      43917230,                                       
                  43917229.                                       

  Anaerobic Soil  MRID:         Observed          Observed        \--
  Metabolism      43917231,                                       
                  43917232.                                       

  Aerobic Aquatic Not Available \--               --              --
  Metabolism                                                      

  Anaerobic       MRID:         \--               --              --
  Aquatic         43917233.                                       
  Metabolism                                                      

  Terrestrial     Not Available \--               --              --
  Field                                                           
  Dissipation                                                     
  -----------------------------------------------------------------------------

**Drinking Water Exposure Modeling**

Number range CHAPTER

*Models*

SCI-GROW (Screening Concentration in Ground Water) is a regression model
used as a screening tool for ground water used as drinking water.
SCIGROW was developed by regressing the results of Prospective Ground
Water studies against the Relative Index of Leaching Potential (RILP).
The RILP is a function of aerobic soil metabolism and the soil-water
partition coefficient. The output of SCI-GROW represents the
concentrations that might be expected in shallow unconfined aquifers
under sandy soils, which is representative of the ground water most
vulnerable to pesticide contamination likely to serve as a drinking
water source. (**Ref. 2**)

FIRST (FQPA Index Reservoir Screening Tool) is a screening model
designed by the Environmental Fate and Effects Division (EFED, 2001a) of
the Office of Pesticide Programs to estimate the concentrations found in
drinking water from surface water sources for use in human health risk
assessment. As such, it provides upper bound values on the
concentrations that might be found in drinking water due to the use of a
pesticide. FIRST is a single event model (one runoff event), but can
account for spray drift from multiple applications. Spray drift
(resulting in direct deposition of the pesticide into the reservoir) is
assumed to be 16% of the applied active ingredient for aerial
application, 6.3% for orchard air blast application, and 6.4% for other
ground spray application. FIRST is hardwired to represent the Index
Reservoir, a standard water body used by the Office of Pesticide
Programs to assess drinking water exposure (Office of Pesticide
Programs, 2002). It is based on a real reservoir (albeit not currently
in active use as a drinking water supply), Shipman City Lake in
Illinois, that is known to be vulnerable to pesticide contamination. The
single runoff event moves a maximum of 8% of the applied pesticide into
the reservoir. This amount can be reduced due to degradation on the
field and the effects of binding to soil in the field. FIRST also uses a
Percent Cropped Area (PCA) factor to adjust for the area within the
watershed that is planted to the modeled crop. The default agricultural
PCA is 0.87. (**Ref. 3 and 4**)

For volatile and semi-volatile compounds, Tier I modeling will tend to
over-estimate EDWCs because there are no parameters in SCI-GROW and
FIRST that explicitly take into account volatility (ie., no vapor
pressure input). Therefore, in reality, more of the compound will be
volatilizing than Tier I can account for. If drinking water levels of
concern are exceeded for over-estimated Tier I EDWCs, Tier II modeling
will be able to refine these EDWCs by including volatility
considerations.

*Modeling Approach and Input Parameters*

Table 5 provides the input parameter values used for modeling of
dimethomorph using SCI-GROW. Table 6 provides the input parameter values
used for modeling of dimethomorph using FIRST. As indicated earlier, no
degradates were included in the modeling because none exceeded 10% of
the applied in the aerobic soil metabolism study.

There were three batch equilibrium studies yielding 11 K~d~'s and
K~OC~'s. Two studies were conducted with foreign soils and yielded lower
K values than the study conducted with domestic soils. The lowest
non-sand K~d~ was selected (as opposed to the K~OC~). Of the two
solubilities (one for the Z and for the E isomers), the highest one was
selected. Since there was no aerobic aquatic metabolism data and the
chemical is stable to hydrolysis, twice the input for the aerobic soil
metabolism was used. In general, the EFED guidance for the selection of
input parameters for FIRST and SCI-GROW was used. The new version of
FIRST V1.1.0 was utilized.

The Percent Cropped Area (PCA) used in this drinking water assessment
was 0.87. It is the default value for "other crops" for which there is
no PCA. It is also the maximum PCA available.

**Table 5. SCI-GROW (v2.3) input parameter values for dimethomorph use
on broccoli^1^**.

  -------------------------------------------------------------------------------
  **PARAMETER (units)**  **VALUE(S)**   **SOURCE**   **COMMENT**
  ---------------------- -------------- ------------ ----------------------------
  Maximum Application    0.2            Label        --
  Rate (lb a.i./A)                      ACROBAT® WP  
                                        Fungicide.   

  Number of Applications 7              Label        Represents most-conservative
  per Year                              ACROBAT® WP  scenario with the maximum
                                        Fungicide.   number of applications.

  Organic Carbon         515            MRID:        Median value out of 11
  Partition Coefficient                 43917234,    available. It is noted that
  (K~oc~; mL/g)                         43917235,    there is more than a
                                        44780202.    five-fold difference in the
                                                     range.

  Aerobic Soil           91.5           MRID:        Average value of two
  Metabolism Half-life                  43917229,    available (117 and 66 days)
  (days)                                43917290.    
  -------------------------------------------------------------------------------

**^1^** Parameters are selected as per Guidance for Selecting Input
Parameters in Modeling the Environmental Fate and Transport of
Pesticides; Version II, February 28, 2002.

**Number range CHAPTERTable 6. FIRST (v1.0) input parameter values for
dimethomorph use on broccoli^1^.**

  -------------------------------------------------------------------------------
  **PARAMETER (units)**  **VALUE(S)**   **SOURCE**   **COMMENT**
  ---------------------- -------------- ------------ ----------------------------
  Application Rate (lb   0.2            Label        --
  a.i./A)                               ACROBAT® WP  
                                        Fungicide.   

  Number of Applications 7              Label        
                                        ACROBAT® WP  
                                        Fungicide.   

  Interval between       7              Label        
  Applications (days)                   ACROBAT® WP  
                                        Fungicide.   

  Percent Cropped Area   0.87           Proposed     National default.
  (decimal)                             label.       

  Soil Partition         3.03           MRID:        Represents the lowest
  Coefficient \[K~d~;                   43917234,    non-sand K~d~ value among
  (mL/g) or K~OC~                       43917235,    eleven values ranging from
  (mL/g~OC~)\]                          44780202.    2.09 to 19.0 mL/g.

  Aerobic Soil           147            MRID:        Represents the 90^th^
  Metabolism Half-life                  43917229,    percentile of the upper
  (days)                                43917230.    confidence bound on the mean
                                                     of two half-life values: 117
                                                     and 66 days; mean 91.5 days,
                                                     std. dev, 25.5

  Wetted in?             No             Label        --
                                        ACROBAT® WP  
                                        Fungicide.   

  Depth of Incorporation 0              Label        --
  (inches)                              ACROBAT® WP  
                                        Fungicide.   

  Method of Application  Aerial spray   Label        --
                                        ACROBAT® WP  
                                        Fungicide.   

  Solubility in Water @  12             \_           At pH 7 the solubility of
  20 ^O^C, unbuffered                                the Z isomer is 12 mg/L and
  (mg/L or ppm)                                      the E isomer is 6 mg/L; the
                                                     maximum value was used.

  Aerobic Aquatic        294            MRID:        No aerobic aquatic
  Metabolism Half-life                  43917229,    metabolism data are
  (days)                                43917230     available and the pesticide
                                                     is hydrolytically stable. 2X
                                                     the aerobic soil metabolism
                                                     half-life input value is
                                                     used.

  Hydrolysis Half-life @ 0              MRID:        Stable.
  pH 7 (days)                           43917226.    

  Aquatic Photolysis     56             MRID:        --
  Half-life @ pH 7                      43917227.    
  (days)                                             
  -------------------------------------------------------------------------------

**^1^** Parameters are selected as per Guidance for Selecting Input
Parameters in Modeling the Environmental Fate and Transport of
Pesticides; Version II, February 28, 2002

*Modeling Result*

**Table 7. Maximum Tier I Estimated Drinking Water Concentrations
(EDWCs) for drinking water risk assessment based on aerial application
of dimethomorph.**

  ------------------- -------------------- --------------- ---------------
  **DRINKING WATER    **USE (rate          **MAXIMUM       
  SOURCE (MODEL       modeled)**           ESTIMATED       
  USED)**                                  DRINKING WATER  
                                           CONCENTRATION   
                                           (EDWC) ( ppb)** 

  Groundwater         Broccoli (1.4 lb     Acute and       0.264
  (SCIGROW)           a.i./A)              Chronic         

  Surface water       Broccoli (1.4 lb     Acute           81.1
  (FIRST)             a.i./A)                              

                      Broccoli (1.4 lb     Chronic         24.7
                      a.i./A)                              
  ------------------- -------------------- --------------- ---------------

*SCI-GROW concentration (ppb) represents the groundwater concentration
that might be expected in shallow unconfined aquifers under sandy soils.
Output is used for both acute and chronic endpoints.*

*FIRST concentrations (ppb) represent untreated surface water
concentrations.*

*The peak day concentration (over 30 years) is used for acute endpoints
and the annual average concentration (over 30 years) is used for chronic
endpoints.*

*The estimated concentrations provided in this assessment are
conservative estimates of concentrations in drinking water. If dietary
risks require refinement, higher tiered crop-specific and
location-specific models and modeling scenarios can be utilized.*

**Monitoring Data**

*Monitoring data usually provide different kinds of information than
modeling (e.g., monitoring reflects current use pattern, underestimates
frequency of occurrence, often misses peaks, inputs cannot be adjusted
as modeled ones can, usually done for purposes other than characterizing
exposure from a particular pesticide), and, consequently, tend to
complement the modeling rather than refine it. In general, a useful
interpretation of monitoring values requires in-depth assessment of the
data, which is beyond the scope of a Tier I assessment.*

**Drinking Water Treatment**

There are no data available on the effects of water treatment on the
possible increasing dissipation and/or the transformation into products
that may be less or more toxic than the parent. (***Ref. 6***)

**[CONCLUSIONS]{.underline}**

In this assessment it has been assumed that the reported value is the
total dimethomorph (Z + E isomers). The results yielded an acute
estimated surface water concentration of 81.1 ppb and a cancer/chronic
drinking water concentration of 24.7 ppb. The groundwater EDWC, suitable
for acute and chronic exposure is 0.264 ppb.

Several uncertainties surround the environmental fate database utilized
in this assessment. Several of the studies were deemed supplemental and
discrepancies were observed as described earlier in the summary of the
environmental fate.

**APPENDIX A. References**

1.  Policy Establishing Current Versions of Exposure Models and
    Responsibility for Model Maintenance (11/06/2002)

2.  SCIGROW: Users Manual (11/01/2001, revised 08/23/2002)

3.  FIRST Users Manual (08/01/2001)

4.  FIRST: A Screening Model to Estimate Pesticide Concentrations in
    Drinking Water (05/01/2001)

5.  Guidance for Selecting Input Parameters in Modeling the
    Environmental Fate and Transport of Pesticides, Version II
    (02/28/2002)

> Number range CHAPTER6 The Incorporation of Water Treatment Effects on
> Pesticide Removal and Transformations in Food Quality Protection Act
> (FQPA) Drinking Water Assessments (10/25/2001)

7.  Tomlin, CDS (ed.) The Pesticide Manual-World Compendium, 11^th^
    edition, British Crop Protection Council, Surrey, England 1997, p.
    416

8.  Food and Agriculture Organization of the United Nations. FAO
    PESTICIDE DISPOSAL SERIES 8. Assessing Soil Contamination: A
    Reference Manual. Appendix 2. Parameters of pesticides that
    influence processes in the soil. Editorial Group, FAO Information
    Division: Rome, 2000 \[ <http://www.fao.org/DOCREP/003/X2570E00.htm>
    \]

**Appendix B. SCI-GROW Output File**

SCIGROW

VERSION 2.3

ENVIRONMENTAL FATE AND EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS

U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL

FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

chemical:Dimethomorph

time is 4/19/2006 11:47:19

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Application Number of Total Use Koc Soil Aerobic

rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

0.200 7.0 1.400 5.15E+02 91.5

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

groundwater screening cond (ppb) = 2.64E-01

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

**Appendix C. FIRST Output File**

RUN No. 1 FOR Dimetomorph ON Broccoli \* INPUT VALUES \*

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) AREA (IN)

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

.200( 1.271) 7 7 3.0 12.0 AERIAL(16.0) 87.0 .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

(FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

147.00 2 N/A 56.00- 6944.00 294.00 282.06

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 DEC 12, 2005

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC)

CONCENTRATION CONCENTRATION

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

81.144 24.736

**Appendix D. Molecular Structure of Dimethomorph**

![](media/image2.png){width="6.5125in" height="2.904166666666667in"}