UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

  SEQ CHAPTER \h \r 1 PC Code:  080805

DP Barcode: 357096, 357099

Date:    June 19, 2009

MEMORANDUM

SUBJECT:      Prometryn (CAS Reg. No. 7287-19-6) Tier I Drinking Water
Assessment

for the Proposed New Uses on Carrots, Okra, Parsley, Cilantro, Celeriac,
and Leafy Petioles

FROM:	Silvia C. Termes, Chemist

		Environmental Fate and Effects Division

		Environmental Risk Branch III

TO:		Barbara Madden

		Risk Integration, Minor Use & Emergency Response Branch

		Registration Division

THRU:	Dana Spatz, Branch Chief

		Environmental Fate and Effects Division

		Environmental Risk Branch III

The Environmental Fate and Effects Division has completed a Tier I
Drinking Water Assessment for registration of proposed new uses on
carrots, okra, parsley, cilantro, celeriac and leafy petioles. These
proposed new uses have been included in the existing labels of two
end-use products containing prometryn as the active ingredient:

Caparol  4L   ( 44.4% prometryn; EPA Reg. No.100-620; Syngenta )

Prometryn 4L Herbicide  (44.4% prometryn by weight; EPA Reg.
No.66222-15; Makhteshim Agan of North America, Inc).	       

The exposure concentrations in drinking water drawn from surface water
were estimated using the Tier I simulation FIRST (Version 1.1.1). 
Concentrations of prometryn in ground water were estimated using the
Tier I SCI-GROW (Version 2.3) regression model.  This assessment
addresses concentrations of parent only; no degradates were included.

Results of Tier I Estimates (FIRST and SCI-GROW)

Table 1 summarizes the Tier 1 estimated concentrations in surface and
ground water.  Application information was extracted from the proposed
labels.

Table 1.  Estimated Concentrations of Prometryn in Drinking Water Drawn
from Surface Water (FIRST) and from Ground Water (SCI-GROW)

Crop	Application  Information	Peak Day (acute)

Concentration, µg/L

Surface water	Annual Average (Chronic) Conc.,

µg/L, Surface water	Ground Water, 

µg/L



Carrots

	3 Applications @ 2 lb ai/acre, 30 days apart, ground	377.4	157.9	23.2

Okra

	1 application @ 1.5 lb ai/acre, ground	96.7	40.5	6.0

Cilantro

	1 application @ 1.6 lb ai/acre, ground	103.2	43.2	6.2



Parsley

	3 applications at 0.5 lb ai/acre, 30 days apart, ground	94.3	39.5	5.8

Celeriac

	1 application @ 4 lb ai/acre, ground	257.9	107.9	15.5

Leafy Petioles	1 application @ 2 lb ai/acre, ground	129.0	54.0	8.0

Cotton	1 application @ 2.8 lb ai/acre, aerial, 0.20 PCA	42.0	17.8	11.2



Table 2 summarizes the exposure modeling input parameters.

Table 2.  Model Input Parameters

Physical-chemical Properties and Environmental Fate Input parameters
Available Data	Selected  Value for Modeling	Source

Molecular Weight , g/mole	241.35	241.35	Product chemistry

Solubility in Water, mg/L	33	33	Product chemistry

Vapor Pressure (25 deg)	1.6E-6 torr	1.6 E-6 torr	Product chemistry

Henry’s Law Constant, atm-m3-mole-1	N/A	9.1 E-9 (est.)	Estimated
(EPIWin, Version 4.0)

Hydrolysis half-life, days	Stable	0	MRID495737-04

Photolysis in Water, days	Stable	0	MRID495737-04

Aerobic Soil Metabolism half-life. days	270 days (1-soil)	3x 270

810 days (as per Input Parameter Guidance)	MRID 4833801

Anaerobic Aquatic Metabolism half-life	N/A	-	N/A

Aerobic Aquatic Metabolism Half-life	N/A	2x 810

1620 days (as per Input Parameter Guidance)	N/A

Sorption Coefficients, Koc	Sand: 246

Loamy sand:  169

Silt loam: 117

Silty clay loam: 448	244 (as per Input Parameter Guidance)	MRID 00148338





Summary of the Environmental Fate of Prometryn

Prometryn is a methylthio-(symmetric) triazine. The chemical names (CAS
and IUPAC) are presented below together with the CAS Registry Number and
chemical structure:

U.S. EPA PC Code:	080805

CA DPR Chemical Code:  502

IUPAC:  N2,N4-diisopropyl-6-methylthio-1,3,5-triazine-2,4-diamine

CAS:   N2,N4-diisopropyl-6-methylthio-1,3,5-triazine-2,4-diamine

CAS Reg. No.:  7287-19-6

Chemical Formula:  C10H19N5S

SMILES: CSc1nc(NC(C)C)nc(NC(C)C)n1

Chemical Structure:

 

Metabolites of Prometryn

 

Name: Prometryn aerobic soil metabolite (27% after one year incubation)

CAS Name:	1,3,5-Triazin-2(1H)-one, 4,6-bis((1-methylethyl)amino)-

IUPAC:	2,4-bis(isopropylamino)-6-hydroxy-s-triazine

CAS Reg No.	 7374-53-0

Name: Prometryn aerobic soil metabolite (1.1% after one year incubation)

IUPAC: 2-amino-4isopropylamino-6-methylthio-s-triazine (GS-1154)

		

The environmental fate properties of prometryn, along with the major and
minor degradates detected in the submitted environmental fate and
transport studies are presented in Table 3.

Table 3.  Environmental Fate and Transport Behavior of Prometyrn

Study	

Value 

	

Major Degradates

Minor Degradates	

MRID #	

Study Classification



Abiotic Hydrolysis	Stable at pH 5, 7, and 9	None	49573704	Acceptable



Direct Aqueous Photolysis	Stable	None	49573705	Acceptable



Soil Photolysis 	Stable	None	49573706	Acceptable



Aerobic Soil Metabolism	 t ½  270 days; (One soil)

Sandy Soil

	2,4-bis(isopropylamino)-6-hydroxy-s-triazine (GS-11526, 27% of the
applied radioactivity after 360 days

2-amino-4isopropylamino-6-methylthio-s-triazine (GS-1154); 1.1% at 30
days	00148338	Acceptable



Anaerobic Soil Metabolism	t ½ 90 days

Stable

41155509	Acceptable



Anaerobic Aquatic Metabolism	No data submitted	No data	-	N/A



Aerobic Aquatic Metabolism	No data submitted	No data	-	N/A

163- Mobility in Soil, Batch-equilibrium Adsorption/

Desorption	K Freundlich, Adsorpotion

0.86 (agricultural sand) to 3.18 (silty clay loam); add other soils

	GS 11526 mobile to very mobile (Freudlich Kads 7.1 to 0.5)

GS-11354 very mobile (Freudlich Kads  0.63-1.9)

	49573713

41875901

41875902

41875903

41875904

41875905	Acceptable

163-2 Volatility from Soil (Laboratory)	Sand soil

Volatility was minimal, 0.99% prometryn volatilized by 30 days	No
41875906	Acceptable



Terrestrial Field Dissipation	t ½  Cotton CA, 105 days

t ½ Cotton CA 71 days

t ½ Cotton  TX  14-30 days

t ½ Cotton TX 14 days

	Prometryn was not detected below 45 cm

CS-11354  detected at 120 cm soil depth



Acceptable  (for flowable concentrate)



Aquatic Field Dissipation	No data	Not applicable	Not applicable	N/A



According to the submitted physical-chemical and environmental fate
data, the degradation of prometryn is driven by microbial (biotic)
activity and not by abiotic processes; however, biotransformation is
slow. The major biotransformation product is GS-11526.  The low
Freundlich adsorption coefficient of prometryn suggests that the
chemical has the potential to run off and/or leach to ground water. 
Prometryn is stable to hydrolysis and direct photolysis in aqueous
media.

Prometryn and its degradates are very mobile to mobile in soil. 
Potential transport mechanisms include runoff to surface water, leaching
to ground water, spray drift, and secondary drift of volatilized or
soil-bound residues leading to deposition onto nearby or more distant
ecosystems. 

The US Geological Survey (USGS) has reported data on the presence of
pesticides in rain and wet deposition in four USA agricultural
watersheds. Among other pesticides, prometryn was detected in rain and
wet deposition in California.

Modeling Outputs - FIRST

CARROTS

A.	3 applications 30 days apart @ 2 lb ai/acre

RUN No.1330 FOR Prometryn        ON   Carrots       * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.000(  5.849)   3  30     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

         377.368                    157.873

B.	One application @ 2 lb ai/acre

RUN No.  12 FOR Prometryn        ON   Carrot        * INPUT VALUES *

 --------------------------------------------------------------------

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

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

 --------------------------------------------------------------------

2.000(  2.000)   1   1     244.0   33.0   GROUND( 6.4)  87.0    .0

 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

 --------------------------------------------------------------------

 METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

 --------------------------------------------------------------------

  810.00        2          N/A       .00-     .00   ******   1620.00

 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

 --------------------------------------------------------------------

      PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

        CONCENTRATION             CONCENTRATION

 --------------------------------------------------------------------

53.952

C.	Two applications@ 2 lb/acre, 30 days apart

 RUN No. 122 FOR Prometryn        ON   Carrots       * INPUT VALUES *

 --------------------------------------------------------------------

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

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

 --------------------------------------------------------------------

2.000(  3.949)   2  30     244.0   33.0   GROUND( 6.4)  87.0    .0

 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

 --------------------------------------------------------------------

 METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

 --------------------------------------------------------------------

  810.00        2          N/A       .00-     .00   ******   1620.00

 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

 --------------------------------------------------------------------

      PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

        CONCENTRATION             CONCENTRATION

 --------------------------------------------------------------------

106.565

OKRA

A.	One application at 1.5 lb ai/acre

RUN No.  21 FOR Prometryn        ON   Okra          * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.500(  1.500)   1   1     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

40.464

b.	Two applications @ 0.75 lb ai 30 days apart

RUN No.  22 FOR Prometryn        ON   Okra          * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.750(  1.481)   2  30     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

39.962

CILANTRO

Single application @ 1.6 lb ai/acre

RUN No.  31 FOR Prometryn        ON   Cilantro      * INPU

----------------------------------------------------------

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

  ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     ARE

----------------------------------------------------------

.600(  1.600)   1   1     244.0   33.0   GROUND( 6.4)  87.

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

----------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC

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

----------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  J

----------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

----------------------------------------------------------

43.161

PARSLEY

A.	Single application @ 0.5 lb ai/acre

RUN No.  41 FOR Prometryn        ON   Parsley       * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.500(   .500)   1   1     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

13.488

B.	Two appications @0.5 lb ai/acre, 30 days apart

RUN No.  42 FOR Prometryn        ON   Parsley       * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.500(   .987)   2  30     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

26.641

C.	Three applications @ 0.5 lb ai/acre, 30 days apart	

RUN No.  43 FOR Prometryn        ON   Parsley       * INPUT VALUES *

--------------------------------------------------------------------

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

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

--------------------------------------------------------------------

.500(  1.462)   3  30     244.0   33.0   GROUND( 6.4)  87.0    .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

--------------------------------------------------------------------

METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

--------------------------------------------------------------------

 810.00        2          N/A       .00-     .00   ******   1620.00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

--------------------------------------------------------------------

     PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

       CONCENTRATION             CONCENTRATION

--------------------------------------------------------------------

39.468

			CELERIAC

 Single application @ 4 lb ai/acre

RUN No.  51 FOR Prometryn        ON   Celeriac      * INPUT VALUES *

 --------------------------------------------------------------------

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

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

 --------------------------------------------------------------------

4.000(  4.000)   1   1     244.0   33.0   GROUND( 6.4)  87.0    .0

 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

 --------------------------------------------------------------------

 METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

 --------------------------------------------------------------------

  810.00        2          N/A       .00-     .00   ******   1620.00

 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

 --------------------------------------------------------------------

      PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)

        CONCENTRATION             CONCENTRATION

 --------------------------------------------------------------------

          257.954                    107.903

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