1

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMCICAL SAFETY AND

POLLUTION PREVENTION

Environmental Fate and Ecological Risk Assessment

Problem Formulation

In Support of Registration Review of Prometryn

Prometryn: N,N'-diisopropyl-6-methylsulfanyl-[1,3,5]triazine-2,4-diamine 

(PC code: 080805, CAS No. 7287-19-6)

Completed By:

Mohammed Ruhman, PhD, Senior Agronomist

Nicholas Mastrota, Wildlife Biologist

Environmental Risk Branch 5

Environmental Fate and Effects Division

March 19, 2013

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Table of Contents

1. Introduction............................................................................................................................. 5

2. Use Characterization............................................................................................................... 6

3. Conclusions from Previous Risk Assessments..................................................................... 12

3.1. Ecological Risk Assessments............................................................................. 12

3.2. Drinking Water Exposure Assessments............................................................. 13

3.3. Clean Water Act Programs................................................................................. 14

4. Environmental Fate and Transport........................................................................................ 15

4.1. Transformation Profile/Products........................................................................ 23

5.1. Effects of Prometryn to Aquatic Organisms...................................................... 24

5.2. Effects of Prometryn to Terrestrial Organisms.................................................. 26

5.3. Expected Toxicity of Transformation Products................................................. 28

5.4. Ecological Incidents........................................................................................... 29

6. Exposure Pathways of Concern ............................................................................................ 31

7. Analysis Plan ........................................................................................................................ 32

7.1 Stressor of Concern ............................................................................................ 32

7.2. Measures of Exposure ........................................................................................ 33

7.3. Measures of Effect ............................................................................................. 34

7.4. Endangered Species Assessments...................................................................... 34

7.5. Endocrine Disruptor Screening Program ........................................................... 34

8. Preliminary Identification of Data Gaps............................................................................... 36

8.2. Environmental Fate ............................................................................................ 36

8.3. Ecological Effects .............................................................................................. 37

9. References............................................................................................................................. 42

10. APPENDICIES.................................................................................................................. 53

10.1 Appendix A: Prometryn Use and Usage Information ....................................... 54

10.1.1 Use Information ........................................................................................... 54

10.1.2. Usage Information....................................................................................... 60

10.2 Appendix B: Prometryn Fate and Transport Properties..................................... 63

10.3 Appendix C: Output from the SIP and STIR Models ........................................ 68

10.4 Appendix D: EIIS Incident Report..................................................................... 71
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List of Tables

Table 1 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weed (refer to abbreviations below): Caparol® 4L (Maximum rates) ............... 7

Table 2 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds (refer to abbreviations below): SuprendTM Herbicide (Maximum rates) 8

Table 3 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds: Cotton-Pro® and Prometryne 4 L (Makhteshim Agan/Loveland 

Products/Winfield Solutions).............................................................................................. 8

Table 4 Use sites and application information for prometryn on crops other than cotton.. 9

Table 5 Summary of Risk Concerns Identified for Prometryn in Previous 

Assessments ..................................................................................................................... 13

Table 6 Physical/chemical parameters and fate properties in abiotic systems for 

prometryn.......................................................................................................................... 16

Table 7 Fate and transport properties of prometryn in biotic systems............................ 16

Table 8 Extraction Procedures and Results ...................................................................... 19

Table 9. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for 

Prometryn.......................................................................................................................... 24

Table 10. Toxicity of Prometryn to Aquatic Plants......................................................... 25

Table 11. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies 

for Prometryn.................................................................................................................... 27

Table 12. ECOSAR Predictions for Acute Toxicity of Prometryn and Hydroxypropazine 

to Aquatic Organisms. ...................................................................................................... 29

Table 13 Status of Environmental Fate Data Requirements for Prometryn ..................... 36

Table 14. Status of Data Requirements for Assessing the Ecological Effects of 

Prometryn to Aquatic Organisms...................................................................................... 37

Table 15. Status of Data Requirements for Assessing the Ecological Effects of 

Prometryn to Terrestrial Organisms.................................................................................. 39
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List of Figures

Figure 1 Prometryn degradation and formation of un-extractable residues in viable 

soil/aquatic systems (data points from one aerobic soil and two aerobic aquatic systems 

(pond and river)................................................................................................................. 21

Figure 2 Suggested degradation pathways for prometryn in varied laboratory and field 

systems.............................................................................................................................. 23
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1. Introduction

Prometryn belongs to the triazine family of herbicides which includes atrazine, simazine, 

propazine, prometon, and ametryn among many others. The majority of the triazine

herbicides are based on s-triazine structure containing two substituted amino groups (NCH3-CH3) with the 3rd carbon atom possessing one of the following groups: chloro (Cl) 

such as atrazine, methoxy (OCH3) such as prometon, or thiomethyl (SCH3) such as 

prometryn. Triazines belong to the group of herbicides which are applied to foliage (may 

be applied to soil as well) and are part of the category that apoplastically translocates in 

the plant (systemic, capable of only upward movement)1

. 

According to the WSSA (Weed Science Society of America) and HRAC (Herbicide 

Resistance Action Committee), the triazine family of herbicides is classified under the C1 

(5) group (photo system II inhibitors)2. The C1 (5) group of herbicides inhibits

photosynthesis by binding to the QB-binding niche on the D1 protein of the photosystem 

II complex in chloroplast thylakoid membranes. Herbicide binding at this protein location 

blocks electron transport from QA to QB and stops CO2 fixation and production of ATP 

and NADPH2 which are all needed for plant growth. However, plant death occurs by 

other processes related to chains of reactions causing loss of chlorophyll and carotenoids 

and in leaky membranes which allow cells and cell organelles to dry and disintegrate 

rapidly. In fish, the mode of action of prometryn toxicity is through neurological effects 

(Popova, 1976).

This document serves as a preliminary problem formulation for the upcoming ecological 

risk assessment for the Registration Review of prometryn. It summarizes information 

currently available to the EPA on the environmental fate and ecological effects of 

prometryn. It also characterizes the registered uses of prometryn in the United States, 

and outlines the analysis plan for assessing ecological risk posed by this herbicide in the 

environment.

 1 http://www.extension.purdue.edu/extmedia/ws/ws-23-w.html

2 WSSA (Weed Science Society of America) Classification of Herbicide Mechanism of 

Action (revised June 10, 2011): http://wssa.net/Weeds/Resistance/WSSA-Mechanism-ofAction.pdf

And HRAC (Herbicide Resistance Action Committee) Classification of Herbicide 

Mechanism of Action: 

http://wssa.net/Weeds/Resistance/HerbicideMOAClassification.pdf
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2. Use Characterization

Labeled Use

Prometryn is an herbicide used for control of broadleaf weeds and grasses on cotton and a 

variety of vegetable and herb crops. Crops include cotton, carrot, celeriac, celery, dill, 

leafy petiole, okra, parsley, pigeon peas, and rhubarb. Prometryn can be applied either 

before (pre-emergence) or after weeds emerge (post-emergence). Timing of application 

may be pre-plant (i.e., before planting the crop), pre-emergence of weeds, postemergence of weeds, or post-transplanting (after transplanting for celery and fennel). In 

cotton, the chemical can be applied post-emergence of weeds (directed to soil not the 

cotton plant), via chemical hoe, and lay-by for winter weed control. Prometryn may be 

applied by ground equipment to all crops, and by aircraft to cotton and pigeon pea. 

Prometryn may also be applied via an irrigation system (chemigation) to certain crops. 

Prometryn is the active ingredient in herbicide products formulated as a liquid 

concentrate or emulsifiable concentrate (EC). Major registered products containing 

prometryn are:

• Caparol® 4L Herbicide (44.4% a.i, Registration No. 100-620, Syngenta)

• SuprendTM Herbicide (79.3% a.i, Registration No. 100-1163, Syngenta). SuprendTM

Herbicide also contains 0.70% trifloxysulfuron-sodium as a second active ingredient.

• Cotton-Pro® (45.41% a.i, Registration No. 66222-116, Makhteshim Agan)

• Prometryne 4 L(44.0% a.i, Registration No. 66222-15, Makhteshim Agan) 

• Prometryne 4 L(44.4% a.i, Registration No. 34704-692, Loveland Products); and

• Prometryne 4 L(44.4% a.i, Registration No. 9779-297, Winfield Solutions)

Furthermore, there are fifteen 24C Special local need (SLN) labels for:

• Caparol 4L for control of w inter and early spring weeds in cotton in the States of 

AL, GA, MO, MS, SC, TN, and VA; for weed control in transplanted celery in CA; 

for herbicide application in/on dill and parsley in FL; and for control of weeds in the 

following seed crops: carrot, parsley, parsnip, and dill in WA;

• Prometryn 4L for weed control in on dill in WA; and

• Prometryne 4L (Loveland) for control of weeds in fennel in CA and Vegetable Pro 

for control of weeds in dill in WA and in celery in AZ.

Additionally, EPA is currently reviewing a petition for a new food use on snap bean and 

dill.

Use rates for a single application range from 0.5 to 3.2 lb a.i./A, and generally 1 to 3 

applications are permitted during a growing season. Use information for application to 

the cotton crop contains many restrictions that are related to one or more of the 

following:

(1) Timing of application (i.e., pre-plant, pre-emergence, winter and early spring 

weed control, winter/fall weed control, pre- and post-emergence winter 
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application for bedded land to be planted cotton, post-emergence directed, 

chemical hoe, and lay-by applications);

(2) Soil characteristics (i.e., texture, presence of caliche layers, and presence of 

calcium carbonates); 

(3) Cotton plant height;

(4) Weed size;

(5) Use site location; and

(6) Type of applications that might be permitted within a year.

Detailed use information for the application parameters to all crops is presented in 

Appendix A (Page 54); however, a summary for cotton use pattern is included in Tables 1 

to 3; and a summary for labeled use on all other crops is included in 

Table 4.

Table 1 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weed (refer to abbreviations below): Caparol® 4L (Maximum rates)

Type of Application

Application Parameters: MSR and MYR (lb a.i/A); MNA; MAI (days); and Others

MSR MNA MYR MAI Notes & Restrictions

(A) Pre-plant 4” incorporated 2.40 1 2.40 N/A No use or lower use rates depend on 

location and soil texture

(B) Pre-emergence (At or shortly after crop planting) 2.80 1 2.80 N/A No use or lower use rates depend on 

location and soil texture. For NM, Apply 

either this application or the Pre-plant 4” 

incorporated, Not both

(C) Pre-emergence reduced rate application (At or shortly 

after crop planting) which is to be followed by application of 

other post emergence herbicides usually within a period of 30 

or more days

1.00 1 1.00 N/A No use or lower use rates depend on 

location and soil texture

(D) Winter and early spring weed control:

* After bedding (from November 1 until 14 days before 

planting cotton); OR

* After bedding (from January 1 until 30 days before planting 

cotton)

1.00 1 1.00 N/A Use only in AL, AR, LA, Mo, MS and TN: 

One of the applications, not both, and 

application may be made before or after 

weeds emerge preferably <2” high

0.75 1 0.75 N/A

(E) Winter/Fall weed control:

* Winter application for bedded land to be planted cotton in 

the following spring OR

* Fall application for bedded land to be planted cotton in the 

following spring

0.80 1 0.80 N/A Use only in TX Gulf Coast and Backlands 

of TX: One of the applications, not both, 

and application may be made before weeds 

emerge.

(F) Pre- Or post-emergence Winter application for bedded 

land to be planted cotton

1.6 1 1.60 N/A Use only in CA: pre-emergence rainfall or 

sprinkler irrigation is necessary. For postemergence, Apply to weeds less than 2” tall.

No use or lower rates depend on soil texture

(G) Post-emergence directed:

* Minimum cotton plant Height = 3-6” and maximum weed 

Height= <1”;

* Minimum cotton plant Height = >6” and maximum weed 

0.5 1 0.5 N/A Use only in AR, LA, MO, MS, TN and TX

0.7 1 0.7 N/A Use in all other cotton regions
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Table 2 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds (refer to abbreviations below): SuprendTM Herbicide (Maximum rates)

Table 3 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds: Cotton-Pro® and Prometryne 4 L (Makhteshim Agan/Loveland 

Products/Winfield Solutions)

Height= <2”

(H) Chemical Hoe (emerged weeds only): 

* Minimum cotton plant Height = 3-6”

* Minimum cotton plant Height = 3-6” and maximum weed 

Height= <1”

0.5 3 1.5 NS

* In cotton 3-6 inches tall, be extremely 

careful to avoid spray contact with cotton 

leaves by applying Caparol 4L with a 

precision applicator equipped with fenders 

or shields,

* In cotton <10” tall, apply only if cotton is 

bedded or flat-planted.

0.7 3 2.1 NS

(I) Lay-By (Cotton at least 12” high) 1.6 2 3.2 NS No use or lower use rates depend on 

location, soil texture, and/or weed size

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly rate (seasonal); MAI= Minimum 

application intervals 

Type of Application Application Parameters: MSR and MYR (lb a.i/A); MNA; MAI (days); and Others

MSR MNA MYR MAI Notes & Restrictions

Post-emergence directed application on picker and pima 

cotton varieties only; When cotton >6” tall and Weeds are 

actively growing with size <6” (Application rate varies with 

weed type/size to be controlled)

1.19 1+

Or

4+

2.14 

Or 

5.15 

(See 

Text)

14 Use only in: AL, AR, AZ, CA, FL, GA, KS, 

KY, LA, MS, NM (certain counties), NC, 

SC, TN, VA, the boot heel area of MO, and 

portions of OK and TX (east of State 

Highway 83 and east of 1-35) 

including/excluding the high plains region 

of West TX and OK.

Do not use in: Rio Grande Valley of TX, 

the Coachella Valley of AZ and CA, and 

sand and loamy sand soils in AZ and CA.

Do not apply aerially

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly rate; ; MAI= Minimum application 

intervals; Numbers in RED/Bold= Calculated values from information provided in the label; noting that 1+ or 4+ means that one more 

application, with lower application rate, may be used; for example: The total for 4applications= 4 x 1.19= 4.76 lb a.i/A and because 5.15 lbs 

a.i/A is permitted a 5th application may be used at a rate= 5.15- 4.76= 0.39 lbs ai/A.

Type of Application (Pesticide Formulation Name)

Application Parameters: MSR and MYR (lb a.i/A); MNA; MAI (days); and Others

MSR MNA MYR MAI Notes & Restrictions

(A) Pre-plant (before planting cotton) (Cotton Pro & 

Prometryn 4L)

2.8 1 2.8 N/A No use or lower use rates depend on 

location and soil texture. Can be aerially 

applied
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Table 4 Use sites and application information for prometryn on crops other than cotton

(Maximum rates/Ground spray for all crops except Pigeon Peas “ground/aerial; 

Chemigation for applications on celeriac, celery/leafy petiole crop groups)

(B) Pre-plant 4” incorporated (Cotton Pro; Prometryn 4

L; Prometryne 4 L/Loveland & Winfield)

2.4 1 2.4 N/A No use or lower use rates depend on 

location and soil texture. For NM, Apply 

either this application or the Pre-plant 4” 

incorporated, Not both. Can be aerially 

applied

(C) Pre-emergence (at planting or shortly after planting)

(Cotton Pro & Prometryn 4 L; Prometryne 4 L/Loveland 

& Winfield)

2.4 1 2.4 N/A Lower use rates depend on location and soil 

texture. Can be aerially applied. Sand or 

loamy sand, shallow soils with caliche subsoils or in areas with caliche outcroppings

(D) Post-emergence Directed: Chemical Hoe (Cotton-Pro; 

Prometryn 4L; Prometryne 4 L/Loveland & Winfield)

0.65 3 2.0 NS Lower use rates depend on location and soil 

texture. Cannot be aerially applied.

(E) Post-emergence Directed: Lay-By 

(emerged/germinating weeds) (Cotton-Pro & Prometryn 

4L; Prometryne 4 L/Loveland & Winfield)

1.6 1 1.6 N/A No use or lower use rates depend on 

location and soil texture. Cannot be aerially 

applied

(F) Winter Weed Control (Cotton-Pro) 2.0 1 2.0 N/A Lower use rates depend on location and soil 

texture. 

(G) Winter Weed Control (Prometryn 4L; Prometryne 4 

L/Loveland & Winfield)

2.0 1 2.0 N/A Lower use rates depend on location and soil 

texture. 

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly rate; ; MAI= Minimum application 

intervals 

Crop: Type of Application

Application Parameters: MSR and MYR (lb a.i/A); MNA; MAI (days); and Others

MSR MNA MYR MAI Product(s), Notes & Restrictions

Carrot: Pre-emergence of crop Plus Postemergence of crop through the 6 leaf stage

2.0

Plus

1.0

1

2

4.0 N/N Caparol 4L, and Prometryn 4L;

Celeriac/Transplanted: After the crop has 6-8 

leaves OR Post-emergence up to 6-8 leaf stage

2.0 1 2.0 N/A Caparol 4L, Prometryn 4L, 

Celery/ Seedbeds: Application (1) 0.8 1 0.8 N/A Caparol 4L, Prometryn 4L, Cotton-Pro, and

Prometryne 4L (Agri- solutions/Loveland); FL 

only; Lower rates for coarse textured soils

Celery/ Direct seeded crop: Pre crop emergence/ 

shortly after planting OR Post crop emergence @ 

2-5 true leaves crop stage and weeds<2” tall

1.6 1 1.60 N/A Caparol 4L, Prometryn 4L, Cotton-Pro, and 

Prometryne 4L (Agri- solutions/Loveland); CA 

only; Lower rates for coarse textured soils

Celery/Transplanted crop: Pre-transplant: Up to 21 

days prior to transplant (1); OR Split Pre & posttransplant: Pre-transplant as above plus posttransplant during the 2-6 week period after 

transplanting and weeds <2” tall OR Posttransplant during the 2-6 week period after 

transplanting and weeds <2” tall

3.2

OR

1.6

1

2

3.2 N/A

Or

N/N

Prometryne 4L (Loveland); Maximum rate is 

for HI; lower use rates depend on location 

(Lower rates for CA, FL, MI, and WI) soil 

texture (lower rates for coarse textured/low 

OM soils
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Celery/Transplanted crop: Post-transplant during 

the 2-6 week period after transplanting and weeds 

<2” tall

3.2 1 3.2 N/A Maximum rate is for HI; lower use rates 

depend on location (Lower rates for CA, TX, 

FL, MI, OH and WI) and soil texture (lower 

rates for coarse textured/low OM soils

Celery Group/Chinese celery and Florence fennel: 

Seedbeds: Application

0.8 1 0.8 N/A Caparol 4L and Prometryn 4L

Celery Group/Chinese celery and Florence fennel:

Pre crop emergence/ at or shortly after planting 

OR Post crop emergence @ 2-5 true leaves crop 

stage and weeds<2” tall

1.6 1 1.6 N/A Caparol 4L and Prometryn 4L; CA only; 

Lower rates for coarse textured soils and is not 

to be used on sand or loamy sand soils

Celery Group/Chinese celery and Florence fennel:

Post-transplant during the 2-6 week period after 

transplanting OR this application may be applied 

once or split into two)

2.0

OR

1.0

1

2

2.0 N/A

NS

Caparol 4L and Prometryn 4L; Maximum rate 

is for (AZ, CA, TX, MI, OH and WI); lower 

use rates depend on location (Lower rates for 

FL) and soil texture (sandy or muck soils)

Cilantro: Post-planting /Pre-emergence of crop 1.6 1 1.6 N/A Prometryn 4L and Caparol 4L and Prometryn 

4L Lower rate of 1.0 for coarse textured soil 

was only specified in Caparol 4L label

Dill: Pre- OR post-emergence before weeds 2” tall 1.6 1 1.60 N/A Prometryne 4L (Loveland); Use on sand or 

loamy sand soils may cause crop injury

Leafy Petiole1: Seedbed After the crop has 2-5 true 

leaves and 7 days after seedbed cover is removed

0.8 1 0.8 N/A Prometryn 4L; FL only

Leafy Petiole1: Direct seeded crop pre OR post 

emergence after the crop has 2-5 true leaves

1.6 1 1.60 N/A Prometryn 4L; CA and AZ only; Lower rate 

for coarse textured soils and no use on sand 

and loamy sand soils

Okra: Pre-emergence OR Pre-emergence & post 

emergence directed

1.5

OR

0.75

1

2

1.5 N/A Caparol 4L and Prometryn 4L; Preemergence= after planting before crop 

emergence; Post directed= when okra plants 

are at 7-9 leaf & weeds 2” tall

Parsley: Pre-emergence, after planting/before crop 

emerges

2.0 1 2.0 N/A Caparol 4L, Prometryn 4L and Prometryne 4L 

(Loveland); CA only; Lower rate of 1.0 for 

coarse textured soils; no used on sandy & 

loamy sand soils

Parsley: After planting 0.5 3 1.5 Refer to 

last 

column

Caparol 4L; Only on Fine textured/high OM 

soils as follows: 1st application 14 days after 

planting; 2nd application 30-day prior to 

harvest; 3rd application to re-growth “after 

cutting” up to 30 days prior to the second 

cutting

Pigeon Peas (Puerto Rico Only): Pre-emergence of 

weeds/crop

3.0 1 3.0 N/A Caparol 4L, Prometryn 4L; Apply at planting 

or immediately after planting before 

crop/weeds emerge; Lower rate of 2.0 for 

loam soils; no used on sandy & loamy sand 

soils
11

Registrants are requested to check the detailed/summary information provided in 

Appendix A (Page 54) and in Table 1 to 3, above, for accuracy. EFED noted those 

labels for Cotton-Pro®; Prometryn 4 L (Makhteshim Agan); Prometryne 4 L (Loveland 

Products), and Prometryne 4 L (Winfield Solutions) contained sufficient application 

details, including non-use sites. However, the labels lack the following important 

parameters that are requested to be included in future labels. The requested parameters 

are:

(1) The maximum yearly rate for each application type, i.e., the nine application types 

stated in the 1st column of Table 1, above, use site such as “TX” and/or soil (e.g., 

sandy loam soil)/cotton plant height (e.g., cotton 3-6”) /weed size (e.g., Weeds <2”);

(2) Which types of applications may be combined within the year; and

(3) Missing information (marked by NS or ?) which are necessary for exposure modeling 

and for inclusion in future labels.

For SuprendTM Herbicide, the label states “Do not exceed a total of 2.7 lbs./A of Suprend 

per season from all applications” (that is 2.14 lbs a.i “prometryn”/A) and continue to state 

“Do not exceed 5.15 lbs. active ingredient of prometryn per acre per season resulting 

from all applications of SuprendTM or Caparol 4L, or other prometryn containing 

products”. The registrant is requested to modify the statements above to clarify if the 

seasonal rate or the yearly rate is 2.14 lbs a.i of prometryn/A/season “assume: year” or 

5.15 lbs a.i of prometryn/A/season “assume: year”.

In addition, registrants are requested to check the information provided in 

Table 4, above, for accuracy and for providing requested missing information necessary 

for exposure modeling and for inclusion in future labels for these products.

Rhubarb: Dormant established crop 2.0 1 2.0 N/A Caparol 4L; Lower rate of 1.6 for coarse 

textured soils

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly (seasonal) rate; MAI= Minimum 

application intervals; N/N= This information is not necessary as it can be estimated from the crop profile. 1

Leafy Petiole= Leafy Petiole= cardoon, celery, Chinese celery, celtuce, Florence fennel, rhubarb, and Swiss chard
12

Usage

The Biological and Economic Analysis Division (BEAD) completed a Screening Level 

Usage Analysis (SLUA) report for prometryn on September 10, 2012 (Appendix A, 

Page 60). According to this report, the greatest amount of use of prometryn is on cotton, 

with an estimated 800,000 lb a.i. applied in the United States annually. On average, 

approximately 10% of the cotton crop is treated with prometryn each year. Prometryn is 

also used widely on celery, with approximately 40,000 lb a.i. applied annually. 

Approximately 85% of the celery crop is treated with prometryn each year. The other 

most significant uses are on carrots (3,000 lb a.i./year) and fallow ground (3,000 lb 

a.i./year).

3. Conclusions from Previous Risk Assessments

3.1. Ecological Risk Assessments

The Agency has conducted multiple ecological risk assessments on prometryn that serve 

as a basis for this scoping document, including ecological risk assessments for a Reregistration Eligibility Decision (USEPA 1996)3

, pesticide effects determination for the 

California Red-legged Frog (June, 2009)4, and a section 3 registration of new uses on 

crop subgroup 4B (August, 2009).5

 The primary risk issues that have been identified are 

for terrestrial and aquatic plants, which is consistent with its use as an herbicide. 

However, risk quotients have also exceeded concern levels for terrestrial and aquatic 

animals as well. These assessments are briefly summarized below.

The most recent, comprehensive assessment conducted for prometryn was for the new 

use registration of crops in crop subgroup 4B (leafy petioles), which was completed in 

August of 2009. For these uses, risk was identified for both aquatic and terrestrial nontarget plants. Risk was identified for chronic effects to fish for some uses. Risk of acute 

toxicity to fish and aquatic invertebrates was determined to not exceed the EPA’s level of 

concern (LOC) for non-endangered species (non-listed species), but exceeded the LOC 

for possible adverse effects to federally threatened and endangered species (listed

species). Risk was identified to terrestrial vertebrates (birds, mammals, reptiles, and 

terrestrial phases of amphibians) because of chronic toxicity. Risk for acute toxicity to 

terrestrial vertebrates was not great enough to exceed the LOC for non-listed species, but 

in some cases exceeded the LOC for possible adverse effects to listed species.

Similar conclusions were reached in the 1996 Re-registration Eligibility Decision (RED) 

(USEPA 1996). The environmental fate assessment characterized prometryn as highly 

persistent in soil and water, and highly mobile in soil. It has low volatility and a low 

 3 http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2009-0081-0087) 

4 Risks of Prometryn Use to Federally Threatened California Red-Legged Frog (Rana aurora draytonii). 

June 17, 2009 URL: http://www.epa.gov/espp/litstatus/effects/redleg-frog/prometryn/analysis.pdf 5 Ecological Risk Assessment for Section 3 New Use Registration of Prometryn (crop subgroup 4B: leafy 

petioles: cardon, celery, Chinese celery, clettuce, fennel, rhubarb, Swiss chard, carrot, celeriac, cilantro, 

okra, and parsley. August, 2009 DP Barcodes: 357096/99, 357334/35.
13

propensity to bio-accumulate. Risk of acute toxicity to fish and aquatic invertebrates was 

determined to not exceed the LOC for non-listed species, but exceed the LOC for 

possible adverse effects to listed species of saltwater fish and invertebrates. Uses of 

prometryn were predicted to pose risk to birds because of chronic reproductive effects. 

This assessment was based on an older avian reproduction study with the mallard (MRID 

41035901) and did not consider information on chronic toxicity to the bobwhite provided 

by a newer avian reproduction study (MRID 44556801). For mammals, some acute RQs 

exceeded the LOC for possible adverse acute effects to listed species. 

In these past assessments, chronic risk to birds was based on avian reproduction studies 

which yielded indeterminate effects for the mallard (MRID 41035901, NOAEC = 500 mg 

a.i./kg-diet, LOAEC > 500 mg a.i./kg-diet) and for the northern bobwhite (MRID 

44556801, NOAEC = 600 mg a.i./kg-diet, LOAEC > 600 mg a.i./kg-diet). These studies 

did not find any treatment-related adverse effect on avian reproduction at any of the test 

levels. Since these studies did not test above 500 mg a.i./kg-diet for mallards or above 

600 mg a.i./kg-diet for bobwhite, the risk of chronic toxicity above these levels is not 

known. Additional chronic toxicity testing would be needed to predict if all uses of 

prometryn would or would not cause chronic risk to birds.

In these past assessments, risk was also determined for both aquatic and terrestrial plants. 

General conclusions from previous assessments are summarized in Table 5.

Table 5 Summary of Risk Concerns Identified for Prometryn in Previous Assessments

Birds Mammals Terrestrial 

Plants

Terrestrial 

Invertebrates

Fish Aquatic 

Inverts

Aquatic 

Plants

Uncertain1 √2 √ LOCs not exceeded √ 3 √3 √

1 Acute risk to birds is low, but chronic risk to birds is uncertain because avian reproduction 

studies did not test at high enough levels to assess chronic risk for all uses of prometryn.

2 Risk to mammals is based on sub-lethal effects caused by chronic exposure.

3 Risk quotients did not exceed the LOC for risk to non-listed species, but in some cases did 

exceed the LOC for potential to harm some listed species. 

√ = at least one LOC has been exceeded.

3.2.Drinking Water Exposure Assessments

A drinking water exposure assessment for proposed new uses on carrots, okra, parsley, 

cilantro, celeriac, and leafy petioles was conducted for prometryn in 2009 (USEPA, 

2009). This referenced assessment addressed concentrations of parent only, and no 

degradates were included. No reference was made to a decision by the EPA committee on 

the residues of concern; it appears that the committee did not consider this issue. 

Exposure estimates of prometryn parent only from currently labeled uses that produce 

maximum exposure (carrots) were 377.4 μg/L (1-in-10-year peak) and 157.9 μg/L (1-in10-year annual mean); no concentration was reported for the 30-year mean for surface 

water, and 23.2 μg/L was reported for ground water. HED and EFED preliminarily 

considered a meeting for ROCKS (Residue of Concern Knowledgebase Subcommittee), 
14

however, it was resolved that the residues of concern for prometryn are parent +major 

degradate hydroxypropazine (GS-11526). 

3.3.Clean Water Act Programs 

Concerning prometryn and the Clean Water Act Programs, the following are stated:

• California has identified 10 miles of the Salt Slough (upstream from the confluence 

with the San Joaquin River) as being impaired from contamination with prometryn.6 

This is the only water body that has been listed by the state as impaired by prometryn 

under Section 303(d) of the Clean Water Act:

http://ofmpub.epa.gov/tmdl_waters10/attains_state.cause_detail_303d?p_cause_group_id=8

85&p_state=CA&p_cycle=2010&p_report_type=

• The Total Maximum Daily Load (TMDL) criteria have not been developed for 

prometryn as no listings were found7 at URL: 

http://iaspub.epa.gov/pls/waters/f?p=ASKWATERS:V_WO_APPROVED_TMDLS:

14484056936224::::P4_OWNER:ATTAINS

• Aquatic benchmarks have been established for prometryn. These benchmarks were 

based on the 1996 RED document and are can be found at URL: 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm.

Section 5.1 of this document identified a more sensitive aquatic endpoint for aquatic 

invertebrates based on findings from a published study (Marchini, 1988). This study 

yielded an LC50 for Daphnia magna of 9.70 mg a.i./L, thereby reducing the acute aquatic 

benchmark to 4850 μg a.i./L. The other aquatic bench marks remain unchanged.

Finally, it is noted that no Office of Water Aquatic Life Criteria are established for this 

chemical. Any data submitted or otherwise located as part of the Registration Review 

process may be used to update aquatic life benchmarks if applicable. 

 6

http://ofmpub.epa.gov/waters10/attains_waterbody.control?p_list_id=CAR5412000019990126155034&p_r

eport_type=T&p_cycle=2010

7 after Choosing: 303(d) Listing & TMDL Information303(d) Listing & TMDL Information; then:

Detailed information from Approved TMDL Documents under Pollutant Name (Prometryn name was not 

found)
15

4. Environmental Fate and Transport

Prometryn [N,N'-diisopropyl-6-rnethyIsulfanyl-[1,3,5]triazine-2,4-diamine; PC code: 

80805 and CAS No. 7287-19-6] is expected to be soluble, semi volatile, and moderately 

hydrophobic. The chemical is stable to laboratory hydrolysis, aqueous and on soil 

photolysis. Prometryn may be considered relatively highly persistent in soil and aquatic 

systems under aerobic conditions. It can also be considered stable under anaerobic 

soil/aquatic conditions. The major degradate of prometryn is GS-11526 with minor 

degradates including GS-11354, GS-16141, and GS-1779. The chemical shows similar 

persistence in the field.

(1) Physical/Chemical Parameters and Fate Properties in Abiotic Systems 

Prometryn is characterized by a water solubility of 33 ppm with one order of magnitude 

higher solubility in organic liquids. The expected concentration in the top 6” of the soil is 

2.0 ppm following maximum single application of up to 4 lbs a.i/A, therefore, applied 

chemical is expected to be soluble within the expected range of moisture present in 

cropped agricultural soils. This means that the applied chemical will be soluble and ready 

to move via leaching and run-off.

The vapor pressure of prometryn indicates that it is a semi-volatile (VP= 1.24 x10-6) and 

is expected to volatilize from dry surfaces; however volatility is expected to be much 

lower from water and wet soils (Henry’s Law Constant= 1.19 x10-8 atm m3 mol-1

). The 

magnitude of transport via volatility depends on prometryn’s ability to mobilize into air 

and its eventual removal through wet and dry deposition of gases/particles and 

photochemical reactions in the atmosphere (t 1⁄2 in air= 0.3 days). Very recently (2008-

2009) 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, Maryland, Indiana, and 

Nebraska (Vogel et al., 2008). The octanol: water partition coefficient for prometryn 

suggests that it is moderately hydrophobic; however, a fish bio-concentration study found 

that prometryn bio-concentrates very little in fish (whole fish BCF = 85x, MRID 

41022701). 

A summary of the physical and chemical properties of prometryn is presented in

Table 6. Finally, prometryn is stable to abiotic processes: hydrolysis, photolysis on soil, 

and direct photolysis (

Table 6). No guideline studies were submitted for prometryn in order to evaluate the 

possible role of indirect photolysis; however, others reported that the chemical is affected 
16

by this process in natural waters (Connell et al., 2004; Cessna, 2008; Kontantinous, 2001; 

and Garbini, 2007).

Table 6 Physical/chemical parameters and fate properties in abiotic systems for 

prometryn. 

Parameter Value

Source MRID 

(Classification)

Physical/chemical properties

Molecular mass (molecular formula) 241.4 g/mol (C10H19N5S) Registrant Data

Solubility (25°C)

In Water: 33 mg/L; Acetone: 300 g/L; Ethanol 

140 g/L; Toluene 200 g/L; 

n-Hexane 6.3 g/L and n-Octanol 110 g/L 001483-34

Vapor pressure (25°C) 1.24 x 10-6 torr 443396-01

Henry’s Law Constant (25°C) 1.19 x10-8 atm m3 mol-1

Calculated from Vapor 

Pressure And Solubility

Octanol: water partition coefficient

(Log KOW and KOW) Log KOW= 3.46; KOW = 2,884 001483-34

Fate properties in abiotic systems

Hydrolysis half-life (22°C) Stable at pH 5, 7, and 9 405737-04 (Acceptable)

Aqueous photolysis half-life (25°C) Stable 405737-05 (Acceptable)

Photolysis on soil1 half-life (25°C) Stable 405737-06 (Acceptable)

t 1⁄2 in air (days) 0.28 (relatively rapid atmospheric oxidation) EPI Suite8

1 Sandy loam soil:70% sand, 27% silt, 3% clay, 0.94% organic matter, pH 5.2, and CEC 6.79 meq/100 g

(2) Fate and Transport Properties in Laboratory and Field Biotic Systems

Detailed laboratory/field fate and transport properties of prometryn are presented in 

Appendix B, page 63; however, a summary for these properties are included in Table 7.

Table 7 Fate and transport properties of prometryn in biotic systems

 8 http://www.epa.gov/opptintr/exposure/pubs/episuitedl.htm

Property System Characteristics Degradation Products (% of Applied) Value

Reference (MRID)

Classification

Aerobic Soil Metabolism Loamy sand soil

Major (MAJ): GS-11526 (max. 27% and 

Non-extractable residues (NER) (max. 31%) 

both @ termination (360 days)

Minor (MIN): GS-11354 declined; and CO2 257 days

001483-38

Acceptable
17

(a) Fate Properties

Laboratory data suggest that the chemical is expected to slowly dissipate, in soil and 

aquatic systems in the environment, principally by biologically induced hydrolysis and 

oxidation. However, biotransformation does not include mineralization to CO2, at least 

under the conditions tested (fate data with other s-triazine herbicides also support that the 

ring structure is recalcitrant to degradation under the vast majority of field conditions). 

Prometryn appears to degrade slowly in aerobic soil (t1⁄2= 257 days; tested in only one 

soil) and in aerobic aquatic systems (90th percentile t1⁄2= 367). No degradation is expected 

Anaerobic Soil Metabolism Sandy loam soil No degradation products formed Stable

411559-01

Acceptable

Aerobic Aquatic Metabolism 

(total system)

River System: 

Water/Sediment

MAJ: GS-11526 (max. 18% and NER (max. 

26%) both @ termination (268days)

MIN: GS-11354 declined; GS-16141 declined; 

GS-17794 no decline; and CO2 236 days

485416-03

Under Review2

Aerobic Aquatic Metabolism 

(total system)

Pond System: 

Water/Sediment

MAJ: GS-11526 (max. 18% and NER (max. 

35%) both @ termination (268days)

MIN: GS-11354 declined; GS-16141 declined; 

GS-17794 no decline; and CO2 110 days

485416-03

Under Review1

Terrestrial Field Dissipation2

CA Sandy loam 

Planted cotton

Degradation in the Top 30 cm:

MAJ: GS-11526 (max. 15 to 31% declined to 

no detection to 2%

MIN: GS-11354 (max. 1 to 4% declined to no 

detection to 1%; Degradates GS-16141 & 

GS-1779 were tracked but not detected

Leaching

* Parent: Show limited leaching to the 15-60 

cm layer (low to high detection frequency at 

max concentrations of 2-5%) and very limited 

leaching to the 60-120 cm layer (low detection 

frequency at max concentrations of 1-5%)

* GS-11526: Shows relatively more leaching to 

the 15-60 cm layer than parent and very limited 

leaching to the 60-120 cm layer;

* GS-11354: Was not detected below 30 cm

103

415464-01/

422539-03

Acceptable

CA Sandy loam 

Bare-ground 71

415464-02/ 

422539-04 

Acceptable

TX Silt loam 

Planted cotton 86

415464-03/

422539-01 

Acceptable

TX Silt loam

Bare-ground 70

415464-04/ 

422539-02 

Acceptable

Soil-Water Partition 

Coefficients (KFOC) L/Kg

Agricultural sand Parent: 245 GS-11354: 174, and GS-11526: 186

418759-01/03

Acceptable

Loamy sand Parent: 169 GS-11354: 86, and GS-11526: 85

Silt Loam Parent: 116 GS-11354: 72, and GS-11526: 84

Silty clay loam Parent: 448 GS-11354: 210, and GS-11526: 1,044

Laboratory Volatility @ 25 oC Sandy soil Minimal volatility (0.99% volatilized in 30 days)

418759-06

Acceptable

Fish bio-concentration Bluegill sunfish

BCFs: 85x (whole fish); 54x (fillet); and 110x (viscera); 

73% depuration in 14 days

410227-01 

Acceptable

1 Under Review: Formal review underway. 2 It is noted that field dissipation data was corrected for recoveries, and that recoveries were low in addition the sampling techniques may 

have cause detection of parent at lower depths and the analytical method for quantification of GS-11526 was unreliable.
18

in anaerobic systems as it was stable in anaerobic soil system (Table 7). Fate data also 

reveal a unique property for prometryn residues that is expected to affect the risk 

assessment. This property is the formation of significant amounts of un-extractable 

residues that were not identified (un-extractable resides in the range of 26 to 35%). Based 

on the lines of evidence presented below, inclusion of un-extractable residues in half-life 

estimates will cause an estimation of longer aerobic soil/aquatic systems half-lives than 

these presented in Table 7. 

Field data show that prometryn is relatively persistent in both planted and bare soil. 

Dissipation half-lives for the top soil, at the four sites, ranged from 86-103 days in cotton 

planted fields and 70-71 days in the same, but bare, fields (Table 7). Relatively lower 

field dissipation half-lives compared to laboratory aerobic soil degradation half-lives is 

probably a reflection of leaching in addition to degradation. Field degradation resulted in 

the same degradation products observed in the laboratory which included the major 

degradate GS-11526 (hydroxypropazine, max. 15 to 31% declined to no detection to 2%)

and GS-11354 (de-ethylametryn, max. 1 to 4%); both degradates declined by the end of 

the 540 days into no detection to 1%-2%. Degradates GS-16141 and GS-1779 were 

tracked but not detected in the field.

(b) Transport Properties

Laboratory data on prometryn suggest moderate mobility (Koc range from 116 to 448 

L/Kg). Additionally, the two tested degradates of prometryn (GS-11354 and GS-11526) 

are expected to be mobile to moderately mobile (Koc range from 72 to 1,044 L/Kg) 

(Table 7). In laboratory column leaching studies, prometryn shows low mobility than 

that suggested by the adsorption/desorption data stated above. Low mobility of prometryn 

was suggested by Field data which showed limited leaching of prometryn to the 15-60 cm 

soil layer and very limited leaching to the 60-120 cm layer. In contrast, field data for the 

major degradate of GS-11526 shows relatively more leaching to the 15-60 cm layer than 

parent, but very limited leaching to the 60-120 cm layer. GS-11354 degradate was not 

detected below the top 30 cm of the soil.

It appears that different conclusions may be drawn from Adsorption/desorption data 

(moderate mobility) versus column leaching/field data (low mobility). This may have 

resulted from aging of the residues in leaching studies but could be explained for field 

studies. It may be help if reasoning or data is submitted to explain the discrepancies

between lab and field transport data. Meanwhile, EFED will base its conclusions on 

adsorption/desorption data which indicate that prometryn and degradates are expected to 

be transported into surface and ground waters. Leaching to ground water is expected to 

occur in vulnerable aquifers, such as those with coarse-textured soils low in organic 

matter. 

Furthermore, a laboratory volatility study showed volatility was minimal (0.99% 

prometryn volatilized by 30 days) suggesting that volatility is not a significant route of 

dissipation for prometryn. Finally, data obtained on fish bio-concentration indicate low 

bio-concentration potential for prometryn (Table 7)
19

Field data show limited leaching of prometryn to the 15-60 cm soil layer and very limited 

leaching to the 60-120 cm layer. In contrast, prometryn degradate GS-11526 shows 

relatively more leaching to the 15-60 cm layer than parent, but very limited leaching to 

the 60-120 cm layer. GS-11354 degradate was not detected below the top 30 cm of the 

soil.

(3) Un-extractable Residues

The maximum amount of un-extractable bound resides in an aerobic soil system was 31% 

of the applied radioactivity, and it was in the range of 26 to 35% of the applied 

radioactivity in two aerobic aquatic systems. These residues increased gradually and 

reached maximums at termination of the experiments with no apparent decline. In this

problem formulation, un-extractable residues were considered as part of residues of 

interest along with two prometryn degradates. Based on the analyses stated hereunder, it 

was decided that un-extractable residues should be considered as part of the stressor. The 

analysis of this problem included examination of the data to answer the following 

question:

Was there an adequate attempt for extracting the residues, and what was the relationship 

between the degradation profile of the chemical and the formation of un-extracted 

residues?

Solvent (methanol or acetone)/water followed by a Soxhlet/solvent were the main 

extraction steps used for extracting prometryn and residues from soil and sediments. 

Table 8 contains a summary of these extraction steps as reported in submitted studies. 

Table 8 Extraction Procedures and Results

Study MRID

1st 

Extraction

2nd

Extraction Yield 1 Notes

Un-extractable Residues

Max. (% of 

Applied)

Time for Max. 

Occurrence

Viable Aerobic Soil 

System

001483-

38

Methanol/ 

Water (8/2)

Methanol 

Soxhlet (all 

samples) N/D

1st and 2nd

Extracts were 

combined and 

the total was 

analyzed

30.8% 2

Experimental 

Termination

Viable Anaerobic Soil 

System 3.7% 3

Sterile Aerobic Soil 

System 3.4% 4

Viable Aerobic Aquatic 

pond System 

485416-

03

Acetone 

(one time)

+

Acetone/

Water (8/2; 

two times)

Acetonitrile/

Water (4/1) 

Soxhlet 

(Samples 

containing 

>10% Unextractable 

residues)

4%

Yield of the 2nd

extraction was 

quantified but 

was not 

combined with 

the 1st extraction 

nor it was 

analyzed

35.0%

Viable Aerobic Aquatic 

River System 4% 26.0%
20

Data show that un-extractable residues in viable aerobic soil and aquatic systems were 

significantly high (26-35%) and that the Soxhlet step extracted only an additional 4% of 

the applied radioactivity (i.e., it is not a very effective extractant). Although the yield of 

this step was quantified, the chemical constituents were not analyzed. Furthermore, the 

level of un-extractable residues, in viable anaerobic soil and sterile aerobic soil systems 

were very low compared to viable aerobic soil and aquatic systems (3.4-3.7% compared 

to 26-35%). Based on these data, it can be stated that the formation of un-extractable 

residues appears to be associated with prometryn degradation (i.e., degradation products 

may constitute major part of the un-extractable residues). Because prometryn is stable in 

anaerobic soil systems and that it is expected to be stable in sterile systems, formation of 

un-extractable residues in these systems is low because of lack of degradation. The 

association between prometryn degradation and formation of relatively high levels of unextractable residues can also be seen in Figure 1.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 60 120 180 240 300 360

% Of Applied Parent

Time (Days)

Parent

Un-extractable Residues

Total Degradation Products

1 Yield from 2nd Extraction (% of Total Extracted): For example the 4% yield entered for the river sediment is calculated as 

follows: the 1st extraction yielded on the average 48% with the 2nd extraction the average yield increased by 2% to 50%, therefore the 

yield in % of total extracted= 2/50= 4%; N/D= Not determined 2

Total time of incubation was 360 days with steady increase of the un-extractable residues (from 0.3 to 30.8%)

3 Total time of incubation was 30 days with no appreciable change in the un-extractable residues (from 3.3 to 3.7%) 4 Total time of incubation was 60 days with no appreciable change in the un-extractable residues (from 1.7 to 3.4%)
21

Figure 1 Prometryn degradation and formation of un-extractable residues in viable 

soil/aquatic systems (data points from one aerobic soil and two aerobic aquatic systems 

(pond and river).

Finally, an attempt was executed to try to further extract the residues. Selected samples 

were further refluxed (following the 1st and 2nd extraction) in neutral/acidic conditions. 

This step yielded, on the average, an additional 3% of the radioactivity from the river 

system (85% of it from neutral reflux + 15% from acidic reflux) and 5% from the pond 

system (81% of it from neutral reflux + 19% from acidic reflux).

Data presented above indicate that there was an attempt to extract the residues; however, 

the attempt was not able to reduce un-extracted residues to an acceptable level. 

Furthermore, the constituents of the additional extract were not characterized. Data also 

show a close association between parent degradation and the formation of the unextractable residues, indicating the possibility that degradation products might be part of 

this residue. Due to the fact that disappearance of the parent might also be due to the 

incomplete extraction (in addition to degradation), the possibility that parent might be 

part of these un-identified un-extracted residues may not be discounted.

(1) The formation of un-extractable residues in various experimental conditions 

including, aerobic soil/aquatic systems and sterile/aerobic and anaerobic soil systems: 

Data show that the level of un-extracted residues was in the range of 26 to 35% of the 

applied radioactivity in one aerobic soil and two aerobic aquatic systems. This is 

compared to 3.4 to 3.7% in a sterile aerobic soil system and a viable anaerobic soil 

system. Due to the fact that no degradation occurs in viable anaerobic soil system and 

in sterile aerobic soil system, formation of un-extracted residues can be related 

closely to prometryn degradation.

(2) A literature review of triazines and their degradation products (Donati and Funari, 

1993) reported the following:

a. De-isopropyl prometryn (a degradation product of prometryn) has been 

identified in soils as the main components of bound residues (i.e., un-extracted 

residues);

b. Hydroxypropazine (a degradation product of prometryn) has been identified 

as of bound residues (i.e., un-extracted residues) associated with the fulvic 

acid extraction;

c. Following one year of incubation of a soil treated with prometryn, it was 

observed that the total bound residues (i.e., un-extracted residues) consisted of 

54% parent or De-isopropyl prometryn, 8% Hydroxypropazine, 18% unidentified compounds and 20% decomposed to CO2 as a result of the 

extraction procedure.

Conclusions on the nature of the un-extracted residues are difficult to ascertain as 

it is necessary to examine extraction procedures used in the above mentioned 

experiments and its possible effects on integrity of the extracted compounds. 
22

However, these reports suggest that the presence of parent and degradates deisopropyl prometryn and/or hydroxypropazine as part of the un-extracted 

residues may not be discounted.
23

N

N

N

OH

N N

CH

H

CH3

CH3

CH

H

H3C

CH3

4.1. Transformation Profile/Products

The only major transformation product of prometryn, identified in submitted 

environmental fate studies, is Hydroxypropazine (GS-11526). Minor transformation 

products which were observed in amounts less than 10% of the applied parent include: 

Prometryn Sulfoxide (GS-16141), Des-ethyl hydroxyatrazine (GS-17794), and Deisopropyl prometryn (GS-11354). Based on these data, the degradation profile of 

prometryn is summarized in Figure 2.

Figure 2 Suggested degradation pathways for prometryn in varied laboratory and field 

systems

 

N

N

N

S

CH3

N N

CH

H

CH3

CH3

CH

H

H3C

CH3

Prometryn Parent (GS-34161)

N

N

N

S

CH3

N N

CH

H

CH3

CH3

CH

H

H3C

CH3

O

De-alkylation Oxidation

De-isopropyl prometryn (GS-11354) Prometryn Sulfoxide (GS-16141)

Hydroxypropazine (GS-11526)

Slow Degradation

Aerobic Soil (t1⁄2 257 days) 

Aerobic Aquatic (t1⁄2= 110-236 days)

Terrestrial Field Dissipation 

(DT50”Dissipation half-lives” 70-103 d)

N

N

N

S

CH3

N

CH

H

CH3

CH3

N

H

H

Des-ethyl-hydroxy atrazine (GS-17794)
24

It is noted that Appendix B, page 63 contains a table summary of the transformation 

products of prometryn and their maximum amounts formed.

5. Receptors

This section summarizes available eco-toxicity data for prometryn. The toxicity 

endpoints provided in these sections are the ones that the EPA intends to use 

quantitatively in the Registration Review ecological risk assessment of prometryn; unless 

more sensitive endpoints become available prior to the time the assessment is conducted. 

It provides acute and chronic toxicity endpoints for the most sensitive test species of 

various taxonomic groups. When more than one toxicity value was available for the same 

species, the lower toxicity endpoint was selected.

5.1. Effects of Prometryn to Aquatic Organisms

Table 9 provides the selected toxicity endpoints for the most sensitive test species of 

various taxonomic groups of aquatic organisms. The acute toxicity data classifies 

prometryn as moderately toxic to fish and aquatic crustaceans, slightly toxic to bivalve 

mollusks, and highly toxic to aquatic plants. With chronic exposure, toxicity studies show 

that prometryn begins to adversely affect the growth of juvenile fish at concentrations 

between 0.62 and 1.2 mg a.i./L, and the growth of young aquatic invertebrates at 

concentrations between 1.0 and 2.0 mg a.i./L. The selected endpoints are from required 

ecotoxicity studies submitted by the registrant, except for acute toxicity to freshwater and 

saltwater invertebrates, for which lower toxicity endpoints were identified from studies 

published in the open literature.

Table 9. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for 

Prometryn

Taxonomic 

Group

Study 

Type Surrogate Species

Toxicity Value

(all units in 

terms of active 

ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Freshwater fish1

Acute

Rainbow Trout

(Oncorhynchus 

mykiss)

96-hr LC50 = 2.91 

mg/L

Moderately 

Toxic

00070686

(Acceptable)

Chronic 

(Early 

LifeStage)

Fathead Minnow

(Pimephales 

promelas)

NOAEC = 0.62 

mg/L

LOAEC = 1.2 

mg/L

(Reduced length)

N/A 43801702

(Acceptable)

Freshwater 

invertebrates

Acute Water Flea 

(Daphnia magna)

48-hr EC50 = 9.70 

mg/L

Moderately 

Toxic

Marchini et al., 

1988 (Eco Ref. 

13154)

Chronic Water Flea

(Daphnia magna)

NOAEC = 1.0 

mg/L

LOAEC = 2.0 

mg/L

(Reduced length)

N/A 40573720

(Acceptable)
25

Taxonomic 

Group

Study 

Type Surrogate Species

Toxicity Value

(all units in 

terms of active 

ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Estuarine/marine 

fish Acute

Sheepshead 

Minnow 

(Cyprinodon 

variegatus)

96-hr LC50 = 5.14 

mg/L

Moderately 

Toxic

40573717

(Acceptable)

Estuarine/marine 

crustacean Acute

Mysid

(Americamysis 

bahia)

96-hr EC50 = 2.32 

mg/L

Moderately 

Toxic

40573718

(Acceptable)

Estuarine/marine 

bivalve Acute

Quahog Clam 

(Mercenaria 

mercenaria)

48-hr EC50 = 21 

mg/L 

Endpoint: shell 

growth

Slightly toxic 40573719

(Acceptable)

Aquatic plants 

and algae

Vascular Duckweed 

(Lemna gibba)

NOAEC = 3.99 

μg/L

EC50 = 11.9 μg/L

Highly toxic 42520901

(Acceptable)

Nonvascular

Freshwater diatom 

(Navicula 

pelliculosa)

NOAEC = 0.288 

μg/L

EC50 = 1.04 μg/L

Highly toxic 42620201

(Acceptable)

1 Freshwater fish may be surrogates for aquatic-phase amphibians.

The greatest concern for aquatic organisms is toxicity to aquatic plants. Large quantities 

of data are available on the toxicity of prometryn to various aquatic plants. These data 

are summarized in Table 10. None of the studies reported in the open literature provided 

a lower 50% inhibition concentration (IC50) value than the ones provided by registrantsubmitted study for vascular aquatic plants (11.9 μg a.i./L for Lemna gibba) or for nonvascular aquatic plants (1.04 μg a.i./L Navicula pelliculosa), and therefore will not be 

used for the RQ calculations. However, these data may be used to generate a species 

sensitivity distribution for aquatic plants and to calculate the hazardous dose for 5% of 

aquatic plant species (HD05) (Aldenberg and Slob, 1993) to better characterize the risk of 

prometryn to aquatic plants.

Table 10. Toxicity of Prometryn to Aquatic Plants

Taxonomic 

Group

Surrogate 

Species

IC50

(μg a.i./L)

NOAEC1

(μg a.i./L)

LOAEC1

(μg a.i./L) Endpoint

Source2

(MRID or 

Eco Ref #)

Duckweed

Lemna gibba 11.9 3.99 8.42 14-day frond 

count 42520901

Lemna 

aequinoctiales 41.0 N/D N/D 8-day population growth

Eco Ref 

78497

Lemna minor 53.8 N/D N/D 6-day population 

growth rate

Eco Ref 

81431

Lemna 

perpusilla 13 N/D N/D 7-day population growth Eco Ref 8628

Spirodela 

polyrhiza 85 N/D N/D 7-day population growth Eco Ref 8628

Green Algae Selenastrum 

capricornutum 11.6 8.1 16 7-day population growth 42520903
26

Taxonomic 

Group

Surrogate 

Species

IC50

(μg a.i./L)

NOAEC1

(μg a.i./L)

LOAEC1

(μg a.i./L) Endpoint

Source2

(MRID or 

Eco Ref #)

Scenedesmus

quadricauda 9.7 N/D N/D 4-day population growth

Eco Ref 

71458

Scenedesmus 

acutus

45.9 N/D N/D 1-day population 

abundance

Eco Ref

78497

Scenedesmus 

acutus

1.27 N/D N/D 4-day population 

growth rate

Eco Ref

78497

Pseudokirchne

riella 

subcapitata

21 N/D N/D

4-day population 

growth Eco Ref

15077

Chlorella fusca 12.4 0.812 N/D 1-day population 

growth rate

Eco Ref

62304 

Chlorella 

pyrenoidosa 9.24 N/D N/D

4-day population 

growth rate

Eco Ref

61983

(Qualitative)

Chlorella 

pyrenoidosa 241 N/D N/D 1-day doubling time

Eco Ref. 

7485

Chlorella 

vulgaris 41.3 N/D N/D

4-day population 

growth rate

Eco Ref

65938

(Qualitative)

Dunaliella 

tertiolecta 53 N/D N/D 4-day population growth

Eco Ref

15077

Chlorococcum 

sp.

724 N/D N/D 1-day doubling 

time Eco Ref 7485

Cryptomonads Cryptomonas

sp.

17.7 15.2 30.3 6-day population 

growth rate

Eco Ref

105114

Diatoms

Navicula 

pelliculosa 1.04 0.288 0.562 5-day population growth

42620201

(Acceptable)

Skeletonema 

costatum

7.82 2.22 4.54 5-day population 

growth

42620202

(Acceptable)

Bluegreen 

algae

Anabaena flosaquae

40.1 20.2 35.2 5-day population 

growth

42520902

(Acceptable)

Anabaena flosaquae

724 N/D N/D

2-day 

Chlorophyll A 

content

Eco Ref. 

7485

Lyngbya sp. 314 N/D N/D 1-day doubling 

time

Eco Ref. 

7485

1 N/D denotes that the value was not determined.

2 Use of these open literature papers will depend on the results of the Agency’s review for acceptability. 

Papers classified a s Quantitative or Qualitative may be used for defining the species sensitivity 

distribution. Results of reviews that have already been completed are noted.

5.2. Effects of Prometryn to Terrestrial Organisms

Table 11 provides the selected toxicity endpoints for the most sensitive test species of 

various taxonomic groups of terrestrial organisms. Prometryn shows little toxicity to 
27

terrestrial wildlife. The acute toxicity data classifies prometryn as practically non-toxic to 

birds and mammals. With chronic exposure, a dietary concentration of 750 mg ai/kg was 

found to cause reduced body weight gain in adult rats and their F1 pups. The NOAEC for 

mammals was established at 10 mg a.i./kg. In birds, chronic exposure to dietary 

concentrations of prometryn up to 500 mg a.i./kg caused no observable adverse effects in 

the mallard, and chronic exposure to dietary concentrations to 600 mg a.i./kg caused no 

observable adverse effects in the northern bobwhite. An acute contact LD50 study with 

the honey bee categorized prometryn as practically non-toxic to bees.

As expected for an herbicide, prometryn is highly toxic to terrestrial plants, with 

exposures less than 0.1 lb a.i./A adversely affecting plant growth. The lowest toxicity 

endpoints were obtained in a vegetative vigor study, and the most sensitive species in this 

study was cucumber, for which the EC25 and NOAEC were 0.006 and 0.019 lb a.i./A, 

respectively. These endpoints will be used in the quantitative risk assessment for 

terrestrial plants.

Table 11. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for 

Prometryn

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(all units in terms of 

measured active 

ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Birds1

Acute

Mallard 

(Anas 

platyrhynchos)

14-d LD50 > 4640 

mg/kg-bw

No mortality at any 

dosage level, but 

reduction in feed 

consumption and 

body weight gain at 

the 4640 mg/kg 

Practically 

non-toxic 00082966

Sub-acute 

dietary

Northern 

bobwhite 

(Colinus 

virginianus)

8-d LC50 > 5000 

mg/kg-diet

One out of 10 died at 

the 5000 mg/kg-diet 

concentration on day 

6; reductions in body 

weight gain and food 

consumption at ≥ 

2500 mg/kg-diet.

Practically 

non-toxic 40457502

Chronic

Mallard 

(Anas 

platyrhynchos)

NOAEC = 500 ppm

LOAEC > 500 ppm

One non-treatment 

related death at 250 

ppm; no significant 

sublethal effects at 

any test level.

N/A 45280301

Mammals

Acute Oral

Laboratory rat 

(Rattus 

norvegicus)

LD50 = 1802 mg/kgbw (males)Practically 

non-toxic 00060314

Acute 

Dermal

Laboratory rat 

(Rattus 

norvegicus)

LD50 > 3170 mg/kgbw

Toxicity 

Category III 00060647
28

Taxonomic 

Group

Study 

Type

Surrogate 

Species

Toxicity Value

(all units in terms of 

measured active 

ingredient)

Acute 

Toxicity 

Classification

Source

(MRID)

Acute 

Inhalation

Laboratory rat

(Rattus 

norvegicus)

LC50 = 4.96 mg/L Toxicity 

Category III 40776601

Chronic

Laboratory rat 

(Rattus 

norvegicus)

NOAEC = 10 mg/kgdiet

(0.65 mg/kg-bw)

LOAEC = 750 

mg/kg-diet

(50.7 mg/kg-bw)

Decreased parental 

and pup weights

N/A 41445101

Insects Acute 

contact

Honey bee 

(Apis mellifera 

L.)

LD50 > 96.7 μg/bee

10.4% mortality at 

96.7 μg/bee

Practically 

non-toxic 00036935

Terrestrial 

plants

Seedling 

Emergence

Dicot – cabbage

NOAEC = 0.038 lb/A

EC25 = 0.014 lb/A

Reduced plant height 

and shoot dry weight

N/A 41035904

Monocot – oat

NOAEC = 0.075 lb/A

EC25 = 0.07 lb/A

Reduced shoot dry 

weight

N/A 41035904

Terrestrial 

plants

Vegetative 

Vigor

Dicot –

cucumber

NOAEC = 0.019 lb/A

EC25 = 0.006 lb/A

Reduced plant height

N/A 41035903

Monocot –

onion

NOAEC = 0.10 lb/A

EC25 = 0.161 lb/A

Reduced shoot dry 

weight

N/A 41035903

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles.

5.3. Expected Toxicity of Transformation Products

Environmental fate studies have shown that degradation and metabolism of prometryn 

results in one major transformation product, hydroxypropazine (GS-11526), and three 

significant minor transformation products: des-ethyl-hydroxy-atrazine (GS-17794), 

prometryn sulfoxide (GS-16141), and deethylametryn (GS-11354). Hydroxypropazine 

and des-ethyl-hydroxy-atrazine are formed with the substitution of the methylthio group 

of prometryn with a hydroxy group. Methylthio-triazines, like prometryn, are generally 

believed to lose much of their phytotoxicity when they are hydrolyzed into a hydroxy-striazine, such as hydroxypropazine (Maier-Bode, 1971). While phytotoxicity data are not 

available for these prometryn transformation products, data for a very similar 

transformation product of atrazine, hydroxyatrazine, show that it has much less 

phytotoxicity than its parent compound, atrazine (Stratton, 1984; Kaufman and Joan 

Blake, 1970). Therefore, neither hydroxypropazine nor des-ethyl-hydroxy-atrazine will 

be included as stressors to nontarget plants. For organisms other than terrestrial plants 
29

(terrestrial animals, fish, aquatic invertebrates, and aquatic plants), hydroxypropazine will 

be considered an ecological stressor because it is a major degredation product (forms 

over 10% of the total residues) and because data are currently insufficient to conclude 

that it is significantly less toxic to these to these taxa than the parent. Toxicity predictions 

generated by ECOSAR (Table 12) as well as toxicity data of comparable atrazine 

transformation products suggest that hydroxypropazine may be less toxic than prometryn 

to aquatic animals and plants. Therefore, three basic toxicity studies are being requested 

to measure the acute toxicity of hydroxypropazine to a freshwater crustacean (Daphnia 

magna), a vascular aquatic plant (Lemna sp.), and a freshwater algae 

(Pseudokirchneriella subcapitata). The decision to consider this product a stressor to 

aquatic organisms will be re-evaluated after these data are submitted and reviewed.

Table 12. ECOSAR Predictions for Acute Toxicity of Prometryn and Hydroxypropazine to Aquatic 

Organisms.

Organisms Class Toxicity Endpoint ECOSAR-Predicted Toxicity (mg/L)

Prometryn Hydroxypropazine

Fish 96-hr LC50 3.97 39.2

Daphnid 48-hr LC50 5.61 26.4

Green Algae 96-hr EC50 0.034 0.106

None of the three minor transformations products will be considered ecological stressors 

in the ecological risk assessment. Prometryn sulfoxide and deethylametryn will not 

included as stressors because they never form more than 10% of the total residues and 

because they are transient products that further hydrolyzed into hydroxy-s-triazines

(Figure 2). Des-ethyl-hydroxy-atrazine will not be included as a stressor because it is a 

minor degradation product (<10% of total residues) and because there is some evidence 

that substitution of the methylthio group of prometryn with a hydroxy group would make 

the compound less toxic to nontarget organisms than the prometryn.

In summary, hydroxypropazine will be considered an ecological stressor for terrestrial 

animals, aquatic animals, and aquatic plants, unless new toxicity data demonstrates that it 

is significantly less toxic than the parent compound (by at least a factor of 10). Therefore, 

barring changes in the conclusion based on new data, predicted residues of this 

transformation product will be added to predicted residues of the parent compound when 

estimating the exposure to terrestrial animals and all aquatic organisms. For terrestrial 

plants, exposure will be base on predicted residues of prometryn alone. Residues of the 

three minor transformation products will not be included in the exposure estimates for 

any nontarget animal or plant.

5.4. Ecological Incidents

The ecological incident information system (EIIS) is an OPP database that houses 

ecological incidents that have been reported to the Agency. When available, EIIS 

includes date and location of an incident, type and magnitude of effects observed in 

various species, use(s) of pesticides known or suspected of contributing to the incident, 

and results of any chemical residue analysis or other analyses conducted during incident 
30

investigation. EIIS incidents are categorized according to the certainty that the incident 

resulted from pesticide exposure. The Avian Monitoring System (AIMS) is a database 

administered by the American Bird Conservancy that contains publicly available data on 

reported avian incidents involving pesticides. Many of the incidents listed in this 

database are also in the EIIS. 

EIIS contains six incidents of crop damage that were linked to exposure to prometryn 

(Appendix D). Five of these incidents involved damage to cotton after direct application 

of this herbicide to that crop. One incident (I019130-056) was attributed to carryover of 

soil residues of prometryn, which allegedly resulted in damage to a rotational corn crop. 

The residues were of Suprend Herbicide (EPA Reg. No. 100-1163) which was 

presumably applied to a cotton crop in the previous season. None of the plant damage 

incidents were attributed to spray drift or runoff of prometryn. 

Three fish kill incidents in EIIS are associated with exposure to prometryn, but in each of 

these incidents the certainty level assigned for prometryn was “unlikely” (I004021-004, 

I004021-005, and I004668-011). All three were related to a series of fish kills that 

occurred in Richland County, Louisiana in 1996. Prometryn was one of 6 herbicides and 

one insecticide that were identified in water samples taken after the incident. These 

incidents were believed to have been caused by runoff of the insecticide profenofos, 

which was present at higher concentrations than prometryn and which is much more toxic 

to fish than prometryn. Prometryn was present at only small concentrations (0.15-0.59 

μg/L). Since these concentrations are far below the lowest acute fish LC50 (2910 μg/L), 

it probably was not a significant contributing factor to the fish mortality.

The AIMS was queried on 9 October 2012. At that time, no avian incident was listed 

which was attributed to prometryn. 

Aggregated incident reports submitted by the registrant between 1998 and 2005 have 

included 5 minor plant incidents attributed to prometryn. These incidents were associated 

with use of either Caparol 4L® (2 incidents) or Suprend® (3 incidents). Unless 

additional information on these aggregated incidents becomes available, they will be 

assumed to be representative of registered uses of prometryn in the risk assessment.
31

6. Exposure Pathways of Concern

Prometryn is highly persistent and highly mobile, but has low volatility and low 

propensity to bio-accumulate. Considering these environmental fate characteristics, the 

following routes are expected to be primary for exposure to non-target organisms:

• Consumption of contaminated food (sprayed food or treated seeds)

• Consumption of contaminated water

• Root uptake (plants)

• Spray drift exposure to organisms and aquatic habitats

• Runoff exposure to soil and aquatic habitats

• Leaching to ground water (for groundwater organisms and plants irrigated by 

ground water)

Because prometryn has been found to not bio-accumulate much in fish (whole fish BCF 

= 85x, MRID 41022701), food-chain routes of exposure, such as the consumption of fish 

by piscivorous wildlife, are not expected to be a major route of exposure. Available data 

indicates low volatility of prometryn suggesting long-distance atmospheric deposition is 

not expected to be a significant route of exposure. However, the US Geological Survey 

(USGS) has reported the presence of pesticides in rain and wet deposition in four USA 

agricultural watersheds (Maryland, Indiana, Nebraska and California) at a 0.05 μg/L 

laboratory reporting limit (Vogel et al., 2008)9 during the 2003-2004 sampling period. In 

California, prometryn was detected in rain in the San Joaquin -Tulare- Merced River10

basin, where a wide variety of crops are grown. Wet depositions were related to storm 

events during the rainy season (December-March). Of 13 detections, a maximum 

concentration of 0.031 μg/L was detected in rain on December 11, 2003 and a maximum 

wet deposition of 0.735 μg/m2 on December 16, 2003. Because data on detection of 

prometryn in rain and wet deposition is limited, spray drift estimates are used as high-end 

estimates for potential atmospheric transport contributions.

Preliminary screens of the potential for drinking water and inhalation to be significant 

exposure pathways were assessed using the SIP (Screening Imbibition Program) and 

STIR (Screening Tool for Inhalation Risk) screening methods, respectively. Results of 

the SIP model indicated that exposure from drinking water alone is a potential concern 

for birds because of its potential to cause chronic effects, but is not a potential concern 

for mammals (Appendix C, page 68). Results of the STIR model confirmed that 

inhalation is not likely to be a significant exposure pathway for wildlife. SIP and STIR 

are described in detail at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm.

 9

 The cropland in West California (samples collected) is dominated by almonds and vineyards. In addition 

to the California studies, other studies were conducted in agricultural watersheds in Maryland, Indiana, and 

Nebraska. 

10 For description of the California’s Merced River Basin see Vogel et al. (2008) and pertinent references 

therein. The environmental setting of the Basin is described in Gronberg & Kratzer (2007).
32

7. Analysis Plan

7.1 Stressor of Concern

In addition to the parent compound, residues of prometryn include un-extractable 

residues plus the chemical degradates of interest: Prometryn Sulfoxide (GS-16141), 

Hydroxypropazine (GS-11526), De-isopropyl prometryn (GS-11354) and Des-ethylhydroxy atrazine (GS-17794). Following consideration of exposure and/or toxicity of all 

residues, it was decided that the stressors of concern for risk assessment will be:

(1) Parent + un-extracted residues for terrestrial plants;

(2) Parent + un-extracted residues + GS-11526 for terrestrial animals; 

(3) Parent + un-extracted residues + GS-11526 for aquatic organisms; unless new toxicity

data (from requested studies) show that GS-11526 is less toxic than parent prometryn 

by at least one order of magnitude .

The major transformation product of prometryn, hydroxypropazine (GS-11526), is 

expected to be much less toxic to terrestrial plants than the parent compound and thus 

will not be considered a stressor of concern for nontarget plants. Also, hydroxypropazine 

will be excluded as a stressor to aquatic animals and plants if requested toxicity test show 

that it is less toxic than prometryn by at least one order of magnitude (i.e., the EC50

values are at least 10 times greater than those for prometryn).

The decision to include un-extractable residues was based upon expected significant 

exposure from these un-identified residues due to persistence and due to unknown 

identity/toxicity. 

Hydroxypropazine (GS-11526) is a major degradate of prometryn, with observed 

maximum concentrations in environmental fate studies of approximately 27% of the 

applied parent in laboratory studies and 31% of the applied parent in field studies. This 

transformation causes the compound to lose its herbicidal activity, and thus it is expected 

to be much less toxic than prometryn to terrestrial plants. Toxicity of hydroxypropazine is 

also expected to be somewhat less than the parent for aquatic organisms as well, although 

the degree of the reduction in toxicity is uncertain at this time. Three acute toxicity tests 

with aquatic animals and plants are being requested to clarify the relative toxicity of

prometryn and hydroxypropazine to these organism. For terrestrial animals, both 

prometryn and hydroxypropazine are expected to have low acute toxicity, and thus their 

toxicities are considered to be similar.

A minor degradation product, desethylhydroxy-atrazine (GS-17794), is another hydroxys-triazine, is not included as a ecological stressor because it is expected to have relatively 

low toxicity and is expected to form in the environment in only small amounts (less than 

5% of the applied material. The other two minor degradation products, prometryn 

sulfoxide and deethylametryn are both transient minor degradation products, with 
33

observed concentrations in the environment of no more than 7% of the amount of parent 

applied. Therefore, these residues will not be considered ecological stressors.

7.2. Measures of Exposure 

EFED will use standard EPA models to evaluate exposure to aquatic and terrestrial 

organisms. Descriptions of these models are available at:

http://www.epa.gov/pesticides/science/models_db.htm

Separate exposure assessments will be conducted for each of the labeled use sites. Similar 

crops that are in a crop group and have identical application restrictions, such as crops in 

the leafy petiole group, will be assessed as a group. Several scenarios will be used to 

assess exposure from use on cotton, representing the different use rates and use 

restrictions that the label imposes for different cotton-growing regions. Separate analyses 

will be conducted to assess exposure from ground, air blast, and aerial applications, as is 

appropriate for the use site.

Exposure will be modeled based on repeated applications of prometryn, with each 

application being made at the maximum application rate, and applications will be 

assumed to be made using the minimum inter-application interval. These applications 

will be assumed to be made until the maximum per-year application rate is reached. 

When necessary, the final application will be set to less than the maximum application 

rate to reach the maximum per-year rate. When the maximum per-year rate is not stated 

on the labels, then the stated maximum number of applications will be used. When

neither the maximum per-season application rate nor the maximum number of 

applications is stated, the maximum number of applications will be calculated based on 

the typical first application date, typical harvest date, minimum application interval, and 

pre-harvest interval.

Predicted aquatic exposures will be estimated using the most current version of the 

Pesticide Root Zone Model (PRZM) and Exposure Analysis Modeling System 

(EXAMS), in conjunction with the most recent version of EFED’s input shell, PE 

(current version 5.0). These models predict maximum and time-averaged expected 

environmental concentrations (EECs) in a standard pond resulting from transport of 

prometryn residues by way of runoff and spray drift. Residues of prometryn in the soil 

will be assumed to degrade between applications. Since laboratory studies have shown 

that prometryn is stable to hydrolysis and photolysis, degradation will be driven by 

aerobic soil and aquatic metabolism. Soil binding will also be assumed based on 

measured Kfoc values and assumed soil types, although these parameters indicate that soil 

binding of prometryn would be minimal.

Exposure to terrestrial animals will be estimated using the latest version of EFED’s 

Terrestrial Residue Exposure model (T-REX, current version 1.5). T-REX predicts 

maximum expected environmental concentrations (EECs) of pesticide residues on 

wildlife food items. These maximum EECs are based on the maximum application rate, 
34

maximum number of applications per season, and minimum inter-application intervals. 

Residues are assumed to dissipate on the food items between the multiple applications. 

Since prometryn is a highly stable compound, the default foliar dissipation half-life of 35 

days will be assumed.

7.3. Measures of Effect 

Toxicity data presented in Section 3 of this problem formulation will be used to calculate 

risk quotients. Any additional information submitted by the registrant or found in the 

open literature prior to conduct of the risk assessment will also be considered. The open 

literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) 

(USEPA, 2013), which employs a literature search engine for locating chemical toxicity 

data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of 

data can also provide insight into the direct and indirect effects of pesticides on biotic 

communities from loss of species that are sensitive to the chemicals and from changes in 

structure and functional characteristics of the affected communities.

7.4. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), 

the Agency will evaluate risks to federally listed threatened and/or endangered (listed) 

species from registered uses of pesticides in Registration Review. The process for 

evaluating potential risks to listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm.

7.5. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential 

adverse outcomes from exposure to chemicals. Collectively, these studies include acute, 

subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, 

developmental, reproductive, and general or systemic toxicity. These studies include 

endpoints which may be susceptible to endocrine influence, including effects on 

endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, 

fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological 

hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, 

developmental and reproductive effects in different taxonomic groups. As part of its 

most recent registration decision, EPA reviewed these data and selected the most 

sensitive endpoints for relevant risk assessment scenarios from the existing hazard 

database. However, as required by FFDCA section 408(p), prometryn is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including 

pesticide active and other ingredients) may have an effect in humans or wildlife similar to 

an effect produced by a “naturally occurring estrogen, or other such endocrine effects as 
35

the Administrator may designate.” The EDSP employs a two-tiered approach to making 

the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays 

to identify the potential of a chemical substance to interact with the estrogen, androgen, 

or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening 

and are found to have the potential to interact with E, A, or T hormonal systems will 

proceed to the next stage of the EDSP where EPA will determine which, if any, of the 

Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to 

identify any adverse endocrine-related effects caused by the substance, and establish a 

dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group 

of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

Prometryn is not among the group of 58 pesticide active ingredients on the initial list to 

be screened under the EDSP. Accordingly, as part of Registration Review, EPA will 

issue future EDSP orders/data call-ins, requiring the submission of EDSP screening 

assays for prometryn. For further information on the status of the EDSP, the policies and 

procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 

screening battery, please visit our website: http://www.epa.gov/endo/.
36

8. Preliminary Identification of Data Gaps 

8.2. Environmental Fate

Table 13 identify environmental fate studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in 

order to support risk assessment.

Table 13 Status of Environmental Fate Data Requirements for Prometryn

OCSPP 

Guideline Data Requirement

Submitted Studies 

(MRID)

Study 

Classifications

Are data needed 

to conduct risk 

assessment?

Justification and Assumptions EPA 

will Make in Absence of Data - Some 

Example texts are include

835.2120 Hydrolysis 405737-04 Acceptable No N/A

835.2240 Aqueous photolysis 405737-05 Acceptable No N/A

835.2410 Soil photolysis 405737-06 Acceptable No N/A

835.4100 Aerobic soil metabolism 001483-38 Acceptable Yes

Half-life used for modeling will be 

multiplied by 31

835.4200 Anaerobic soil metabolism 411559-01 Acceptable No N/A

835.4300 Aerobic aquatic metabolism 485416-03 Under review

835.4400 Anaerobic aquatic metabolism None Submitted Yes Chemical will be considered Stable

835.1230

835.1240

Adsorption/ desorption and 

leaching

418759-01 Acceptable

No N/A

418759-02 Acceptable

418759-03 Acceptable

835.1410 Volatility – laboratory 418759-06 Acceptable No N/A

835.6100

Terrestrial field dissipation

415464-01 &

422539-03 Acceptable

No N/A

415464-02 &

422539-04 Acceptable

415464-03 &

422539-01 Acceptable

415464-04 &

422539-02 Acceptable

Analytical method in soil None Submitted Yes Required

835.6200 Analytical method in water None Submitted Yes Required

850.1730 Fish bio-concentration 410227-01 Acceptable No N/A

1 As per model input guidance11

Examination of the list of submitted studies (Table 13) indicates the following data gaps:

(1) Aerobic soil metabolism: only one aerobic soil study was submitted. EFED 

requests two more studies on soils representing the major areas where prometryn 

will be used (main cotton areas of the country). Before conducting these studies, 

 11 Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides. URL: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm#Przm
37

further effort is to be executed to show that the extraction method to be used is the 

most efficient method available. It is recommended that a literature search is 

performed for the best extraction method due to the fact that other researchers had 

reported extraction methods showing un-extracted residues containing parent and 

degradates; 

(2) Anaerobic aquatic metabolism study: none was submitted and because the 

chemical is stable under anaerobic soil conditions, it will be considered also stable 

under anaerobic aquatic conditions unless a study is submitted; and

(3) Environmental Chemistry Methods (ECMs) for soil and water along with their 

independent laboratory validation (ILVs). It is recommended to device state of the 

art methods that employ existing multi-pesticide analytical procedures; when 

possible. 

8.3. Ecological Effects

Table 14 and Table 15 identify the status of study requirements for assessing the 

ecological effects of prometryn to aquatic organisms and terrestrial organisms, 

respectively. These tables identify ecological effects studies that offer data for each 

guideline requirement, as well as acceptability classifications of those studies, and 

whether additional data are needed in order to support risk assessment. 

Table 14. Status of Data Requirements for Assessing the Ecological Effects of Prometryn to 

Aquatic Organisms 

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed to 

conduct 

risk 

assessment?

Justification and Assumptions 

EPA will Make in Absence of 

Data - Some Example texts are 

included

850.1010 Freshwater 

invertebrate 

acute toxicity

00070146 Acceptable No --

850.1025

850.1055

Saltwater 

invertebrate 

acute toxicity

(bivalve)

40573719 Acceptable No --

850.1035

850.1045

Saltwater 

invertebrate 

acute toxicity

(crustacean) 

40573718 Acceptable No --

850.1075 Freshwater 

fish acute 

toxicity 

00070686 Acceptable No --

00070686 Supplemental

00040692 Acceptable1

00020692 Acceptable1

00121154 Acceptable2

00121155 Acceptable2
38

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed to 

conduct 

risk 

assessment?

Justification and Assumptions 

EPA will Make in Absence of 

Data - Some Example texts are 

included

850.1075 Saltwater fish 

acute toxicity 

40573717 Acceptable No --

850.1300 Freshwater 

invertebrate 

life cycle 

40573720 Acceptable No --

850.1350 Saltwater 

invertebrates 

life cycle 

-- -- Yes A guideline compliant saltwater 

invertebrate life cycle test is 

needed. Prometryn is highly 

persistent in aquatic 

environments. Its high mobility 

and use in coastal areas makes it 

likely to enter saltwater 

environments in significant 

concentrations. Also, in previous 

risk assessments, aquatic EECs 

have been greater than 0.01 the 

acute EC50 for the mysid.

850.1400 Freshwater 

fish 

early-life 

stage

43801702 Acceptable No NOTE: MRID 43801702 was 

originally classified as 

Supplemental but was upgraded to 

Acceptable in 1997.

40573721 Invalid

850.1400 Saltwater fish 

early-life 

stage 

No --

850.1500 Fish life cycle No --

850.1735

850.1740

Whole 

sediment 

acute 

invertebrate 

No Due to the high persistence of 

prometryn, acute sediment 

toxicity testing is not required at 

this time.

Nonguideline 

studies, 

850.1760 

850.1770, 

850.1780, 

in prep.

Whole 

sediment 

chronic 

invertebrate

Yes Guideline-compliant studies are 

needed on the chronic toxicity of 

prometryn to sediment-dwelling 

organisms. Chronic studies are 

requested because prometryn is 

highly persistent in aquatic 

environments, is expected to bind 

to sediment, and the expected 

peak pore water concentration is 

greater than 1/10 the acute EC50 

for the Daphnia magna and the 

mysid.

850.4400 Aquatic plant 

toxicity test 

using Lemna

spp.

40520901 Acceptable No --
39

OCSPP

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed to 

conduct 

risk 

assessment?

Justification and Assumptions 

EPA will Make in Absence of 

Data - Some Example texts are 

included

850.4500 Algal toxicity 42520903 Acceptable No --

42620201 Acceptable

42620202 Acceptable

850.4550 Cyanobacteria 

(Anabaena 

flos-aquae) 

Toxicity

42530902 Acceptable No

1 This study was conducted with Primaze 80W (40% prometryn and 38% atrazine).

2 This study was conducted with Caparol 80W (80% prometryn).

Table 15. Status of Data Requirements for Assessing the Ecological Effects of Prometryn to 

Terrestrial Organisms

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Current Additional Data 

Need

850.2100 Avian oral 

toxicity

00082966 Acceptable No Because of the very low 

toxicity observed in the avian 

acute oral and avian dietary 

test, an acute oral test with a 

passerine species is not needed

at this time.

850.2200 Avian dietary 

toxicity 

40457502 Acceptable No --

00070686 Acceptable

00070686 Supplemental1

850.2300 Avian 

reproduction

41035901 Acceptable No

44556801 Acceptable

41035902 Invalid

NonguidelineAvian 

inhalation

No

850.3020 Honey bee 

acute contact 

toxicity

00036935 Acceptable No --

850.3030 Honey bee 

residue on 

foliage

No --

850.3040 Field testing 

for 

pollinators

No --

850.4100 Seedling 

emergence

40457504

(Tier 1)

Acceptable No --
40

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID)

Study 

Classifications

Are data 

needed for 

risk 

assessment?

Current Additional Data 

Need

and seedling 

growth

41035903

(Tier 2)

Acceptable No

850.4150 Vegetative 

vigor

40457505

(Tier 1)

Acceptable No

41035904 Acceptable No

1 MRID 00070686 included avian dietary tests with the mallard and the northern bobwhite. The test with 

the mallard was Acceptable whereas the test with the northern bobwhite was Supplemental.

The available data on the ecological effects of prometryn to aquatic and terrestrial 

organisms are complete with the exception of data on the chronic toxicity to saltwater 

mysid. A study testing the life-cycle toxicity of prometryn to the mysid (Guideline No. 

850.1350) is needed to fill this data gap. The following criteria make this study required 

for prometryn:

• Prometryn has outdoor terrestrial use sites that occur in coastal areas and could 

result in exposure to estuarine and marine habitats.

• The high mobility and persistence of prometryn make significant movement of 

prometryn into estuarine and marine habitats likely.

• Prometryn is a persistent pesticide (stable to hydrolysis and aqueous photolysis at 

22°C)

• In previous assessments, the EEC in water was found to be greater than 0.01 the 

acute EC50 of the mysid.

This study is needed to assess the risk of the use of prometryn to saltwater invertebrates 

living in estuarine and marine habitats, and likelihood that prometryn may affect listed 

species of invertebrates that occur in these habitats. Without data from this study, the 

EPA would need to estimate the chronic toxicity of prometryn to the mysid using the 

acute-to-chronic ratio method. This would increase the uncertainty of the risk 

conclusions for these species.

Sediment Toxicity Testing

No data are available on the toxicity of prometryn to sediment-dwelling invertebrates. 

The use pattern, chemical properties, estimated exposure, and toxicity profile of

prometryn indicate need for chronic (life cycle) sediment toxicity tests to fully evaluate 

potential risks to benthic invertebrates. Prometryn meets the following criteria for 

sediment toxicity testing, as defined in the Code of Federal Regulations:

• The EEC in sediment is greater than one-tenth of the acute EC50 values. 

PRZM/EXAMS runs were executed for three cotton scenarios (CA, MS and NC) 

with a total application rate of 5.5 lbs a.i/A assumed to be applied as follows: 2.0 
41

lbs a.i/A as winter application + 2.8 lbs a.i/A as pre-plant incorporated to 10 cm + 

0.7 lbs a.i/A as post-emergence application. The results indicates that the peak 

pore water EECs range from as low as 19 ppb for CA to as high as 1,200 ppb for 

NC. One tenth the acute EC50 is 970 ppb when based on the daphnid acute EC50

and 232 ppb when based on the mysid EC50.

• The half-life of the pesticide in sediment is >10 days.

The aerobic soil metabolism half-life is 257 days (MRID 00148338) and the 

aerobic metabolism half-lives are 110 days (pond system, MRID 48541603) and 

236 days (river system, MRID 48541603)

• The log Kow is greater than 3.

The log Kow for prometryn is 3.46.

Life-cycle sediment toxicity studies needed for risk ecological assessment include two 

freshwater species (the midge, Chironomus dilutus and the amphipod, Hyalella azteca) 

and one saltwater species (the amphipod, Leptocheirus plumulosus). Multiple species

are being recommended in order to account for differential sensitivity and exposure 

potential of benthic invertebrates to prometryn. Specifically, the following chronic 

studies are requested:

1. Test Method 100.4: Hyalella azteca 42-d Test for Measuring the Effects of 

Sediment Associated Contaminants on Survival, Growth, and Reproduction in 

USEPA 2000 Methods for Measuring the Toxicity and Bioaccumulation of 

Sediment-associated Contaminants with Freshwater Invertebrates EPA 600/R99/064 (proposed guideline number 850.1770)

2. Test Method 100.5: Life-cycle Test for Measuring the Effects of Sedimentassociated Contaminants on Chironomus dilutus or C. tentans in USEPA 2000 

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated 

Contaminants with Freshwater Invertebrates EPA 600/R-99/064 (proposed 

guideline number 850.1760)

3. Leptocheirus plumulosus in USEPA 2001 Method for Assessing the Chronic 

Toxicity of Marine and Estuarine Sediment-associated Contaminants with the 

Amphipod Leptocheirus plumulosus EPA 600/R-01/020 (proposed guideline 

number 850.1780)

Toxicity testing with Transformation Products

As discussed in Section 5.3, indirect evidence indicates that the major transformation 

product, hydroxypropazine (GS-11526), is likely to be less toxic than the parent 

compound, prometryn, but some basic acute aquatic toxicity testing is needed to confirm 

this. Acute hydroxypropazine toxicity tests are requested with one aquatic invertebrate 
42

and two aquatic plants, one vascular and one nonvascular. Specifically, the following 

guideline test are requested for hydroxypropazine:

• 850.1010 Aquatic invertebrate acute toxicity, freshwater daphnids

• 850.4400 Aquatic plant toxicity test using Lemna sp.

• 850.5400 Algal toxicity using green algae Pseudokirchneriella subcapitata

Tier 2 tests are recommended for the aquatic plant testing of hydroxypropazine, although 

tier 1 test would be acceptable if they show inhibition of less than 50% at a concentration 

of 2.5 mg ai/L or greater. These data would be used to determine if hydroxypropazine 

should be considered an ecological stressor and included in estimates of total toxic 

residues in the ecological risk assessment. This transformation product will be included 

if any of these tests show that hydroxypropazine has toxicity equal to or greater than 

prometryn. Otherwise, the transformation product will not be included, and the risk 

assessment will be based on exposure to the parent compound alone.

9. References

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001483-34

405737-04

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405737-05

Lawrence, L.J. 1987. Solution photolysis of 14C prometryn under natural sunlight 

conditions. Laboratory Project No. 195. Report No. 1138. Study performed by 
44

Pharmacology and Toxicology Research Laboratory, Lexington, KY, and submitted by 

Ciba-Geigy Corporation, Greensboro, NC.

405737-06

Lawrence, L.J. 1987. Soil surface photolysis of 14C prometryn under natural sunlight. 

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Ciba-Geigy Corporation, Greensboro, NC.

001483-38

Ellgehausen, H. 1979. Degradation of prometryn (Gesagard) in aerobic, 

aerobic/anaerobic, and sterile /aerobic conditions. Project report 20/79. Biochemistry 

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Switzerland.

41155901

Saxena, A.M. 1989. Aerobic/anaerobic soi1 metabolism of 14C prometryn. Laboratory 

Study ID: HLA 6015-384. Unpublished study performed by Hazleton Laboratories 

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485416-03

Schulze-Aurich. 2000. Degradation and Metabolism of [UYC]triazine G-34161 in two

Aerobic Aquatic Systems under laboratory, including amendment 1. Study 

Number 98SA01. Unpublished study performed by Novartis Crop Protection

AG Environmental Safety/Eco-chemistry, 4002 Basel, Switzerland and submitted by

Syngenta Crop Protection, LLC, 410 Swing Road, P.O Box 18300, Greensboro, NC 

27419-8300.

418759-01

Kestrson, A., 1991. Soil adsorption/desorption of [14C] prometryn by the batch 

equilibrium method. Laboratory Project ID: project No. 526; Ciba-Geigy Protocol No. 

190-90. Unpublished study performed by Pharmacology and Toxicology Research 

Laboratory, Lexington, KY, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

418759-02

Kestrson, A., 1991. Soil adsorption/desorption of [14C] GS-11354 by the batch 

equilibrium method. Laboratory Project ID: project No. 528; Ciba-Geigy Protocol No. 

188-90. Unpublished study performed by Pharmacology and Toxicology Research 

Laboratory, Lexington, KY, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

418759-03

Kestrson, A., 1991. Soil adsorption/desorption of [14C] hydroxypropazine by the batch 

equilibrium method. Laboratory Project ID: project No. 527; Ciba-Geigy Protocol No. 

189-90. Unpublished study performed by Pharmacology and Toxicology Research 

Laboratory, Lexington, KY, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

418759-06
45

Jackson S.B. 1991. Laboratory volatility of 14C prometryn.. Laboratory Project ID: PTRL 

project No. 521. Study performed by Pharmacology and Toxicology Research Laboratory 

East, Richmond, KY, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

410227-01

Forbis, A.D. and T.D.J. Halls. 1988. Uptake, depuration and bioconcentration of 14Cprometryn to bluegill sunfish (Lepomis macrochirus), and characterization of 14Cprometryn residues in fish tissue and water. Laboratory Study No. 361341. Unpublished 

study performed by Analytical Bio-Chemistry Laboratories, Inc., Columbia, MO, and 

submitted by Ciba-Geigy Corporation, and submitted by Ciba-Geigy

415464-01

A. Landis International, Inc. 1990. Caparol 4L terrestrial field dissipation study on 

cotton in California. LA Protocol No. 1641-88-71-16-11B-15.Unpublished study 

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Labs., New Ulm, MN; and submitted by Ciba-Geigy Corporation, Greensboro, NC.

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GS-11525 from California cropped field dissipation soil samples. MVTL Protocol 

No. 8808C. Unpublished study performed by Minnesota Valley Testing Labs. Inc., 

New Ulm, MN; and submitted by Ciba-Geigy Corporation, Greensboro, NC.

422539-03

Fleming, P.L., and Wiepke, T. 1990. Supplemental to MRID 4154601. Caparol 4L Field 

Dissipation Study on Cotton in California. Laboratory Project ID: 8808C. Unpublished 

study performed by Minnesota Valley Testing Laboratories, Inc., New Ulm, MN, and 

submitted by Ciba-Geigy Corporation, Greensboro, NC.

415464-02 

A. Landis International, Inc. 1990. Caparol 4L terrestrial field dissipation on 

bareground in California. LA Protocol No. 1641-88-71-16-hed study performed 

by Landis International, Inc., Minnesota Valley Testing Labs., Inc., New Ulm, 

MN; and Geigy Corporation, Greensboro, NC. 

B. Anderson. S.C. 1990a. Residue determination of prometryn, GS-11354, and GS11526 from California bare ground field dissipation soil samples. MVTL Protocol 

No. 8808D. Unpublished study by Minnesota Valley Testing Labs., Inc., New 

Ulm, MN; and submitted by Ciba-Geigy Corporation, Greensboro, NC

422539-04

Fleming, P.L., and Wiepke, T. 1990. Supplemental to MRID 415464-02. Caparol 4L 

Field Dissipation Study on Bare Ground in California. Laboratory Project ID: 8808D. 

Unpublished study performed by Minnesota Valley Testing Laboratories, Inc., New Ulm, 

MN, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

415464-03
46

A. Landis International, Inc. 1990c. Caparol 4L terrestrial field dissipation on cotton 

in Texas. LA Protocol No. 1641-88-71-16-11B-13. Unpublished study performed 

by Landis International, Inc., Valdosta, GA, esota Valley Testing Labs., Inc., New 

Ulm, MN; and submitted by gy Corporation, Greensboro, NC. 

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8808A.Unpublished study performed by Minnesota Valley Testing Labs, Inc., 

New Ulm, MN; and submitted by Ciba-Geigy Corporation, Greensboro, NC.

422539-01

Fleming, P.L., and Wiepke, T. 1990. Supplemental to MRID 41546-03. Caparol 4L Field 

Dissipation Study on Cotton in Texas. Laboratory Project ID: 8808A. Unpublished study 

performed by Minnesota Valley Testing Laboratories, Inc., New Ulm, MN, and 

submitted by Ciba-Geigy Corporation, Greensboro, NC.

415464-04

A. Landis International, Inc. 1990b. Caparol 4L terrestrial field dissipation on bareground in Texas. LA Protocol No. 1641-88-71-16-21E-14. Unpublished study 

performed by Landis International. Inc., Valdosta, GA, and Minnesota Valley 

Testing Labs., Inc., New Ulm, MN; and submitted by Ciba-Geigy Corporation, 

Greensboro, NC. 

B. Anderson. S.C. 1990c. Residue determination of prometryn GS-11354, and GS11526 from Texas bare ground field dissipation soil samples. MVTL , Protocol 

No. 8808B. Unpublished study performed by Minnesota Valley Testing Labs Inc., 

New Ulm, MN; and submitted by Ciba-Geigy Corporation, Greensboro, NC

422539-02

Fleming, P.L., and Wiepke, T. 1990. Supplemental to MRID 415464-04. Caparol 4L 

Field Dissipation Study on Bare Ground in Texas. Laboratory Project ID: 8808B. 

Unpublished study performed by Minnesota Valley Testing Laboratories, Inc., New Ulm, 

MN, and submitted by Ciba-Geigy Corporation, Greensboro, NC.

Submitted Ecological Effects Studies

71-1 Avian Single Dose Oral Toxicity

MRID DOC# Citation Reference

56908 Summary 

report

Ciba-Geigy Corporation (1967) Toxicology: (Evik(R)). (Reports by 

various sources; unpublished study including IBT nos. B4715, 

C4716 and P4709, received Apr 14, 1971 under 1G1142; CDL: 

090929-B) 

70686 2028297

2028298

Beliles, R.P.; Scott, W.; Knott, W. (1965) Prometryne: Safety 

Evaluation on Fish and Wildlife (Bobwhite Quail, Mallard Ducks, 
47

2028299

2028300

2028301

Rainbow Trout, Sunfish, Goldfish). (Unpublished study received 

Dec 29, 1977 under 100-542; prepared by Woodard Research 

Corp., submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:232551-B) 

82966 2028303 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Acute Oral 

LD50--Mallard Duck: Project No. 108-131. (Unpublished study 

received Dec 29, 1977 under 100-542; prepared by Wildlife International Ltd. and Washington College, submitted by Ciba-Geigy 

Corp., Greensboro, N.C.; CDL:232551-C) 

40457501 DER not 

located

Fletcher, D. (1984) Acute Oral Toxicity Study with Prometryn 

Technical in Bobwhite Quail: Lab Study Number BLAL No.

84QD44. Unpublished study performed by Bio-Life Associates. 21 

p. 

71-2 Avian Dietary Toxicity

MRID DOC# Citation Reference

70686 2028298

2028301

Beliles, R.P.; Scott, W.; Knott, W. (1965) Prometryne: Safety 

Evaluation on Fish and Wildlife (Bobwhite Quail, Mallard Ducks,

Rainbow Trout, Sunfish, Goldfish). (Unpublished study received 

Dec 29, 1977 under 100-542; prepared by Woodard Research 

Corp., submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:232551-B) 

40457502 2028306 Fletcher, D. (1984) 8-Day Dietary LC50 Study with Prometryn 

Technical in Bobwhite Quail: Study Number BLAL No. 84QC43. 

Unpublished study performed by Bio-Life Associates. 23 p. 

40457503 DER not 

located

Fletcher, D. (1984) 8-Day Dietary LC50 Study with Prometryn 

Technical in Mallard Ducks: Study Number BLAL No. 84DC44. 

Unpublished study performed by Bio-Life Associates. 23 p. 

71-4 Avian Reproduction

MRID DOC# Citation Reference

41035901 2028315 Fletcher, D.; Pedersen, C. (1989) Prometryn Technical: Toxicity 

and Reproduction Study in Mallard Ducks: Study No. 87 DR 21. 

Unpu- blished study prepared by Bio-Life Associates, Ltd. 55 p. 

41035902 2028316 Fletcher, D. (1989) Prometryn Technical: Toxicity and 

Reproduction Study in Bobwhite Quail: Study No. 87 QR 23. 

Unpublished study prepared by Bio-Life Associates, Ltd. 120 p. 

43370401 Response 

to the 

Review

Peters, G. (1994) Response to the Review of: Prometryn 

Technical: Toxicity and Reproduction Study in Bobwhite Quail: 

Lab Project Number: 87/QRP/23. Unpublished study prepared by 

Ciba Crop Protection. 61 p. 

43370402 Response 

to the 

Review

Peters, G. (1994) Response to the Review of: Prometryn 

Technical: Toxicity and Reproduction Study in Mallard Ducks: Lab 

Project Number: 87/DRP/21. Unpublished study prepared by Ciba 

Crop Protection. 67 p. 
48

44556801 2028328 Gallagher, S.; Beavers, J.; Jaber, M. (1998) Prometryn Technical: 

A Reproduction Study with the Northern Bobwhite (Colinus 

virginianus): Lab Project Number: 108-387: 14-97. Unpublished 

study prepared by Wildlife International, Ltd. 159 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID DOC# Citation Reference

70686 2028297

2028299

2028300

Beliles, R.P.; Scott, W.; Knott, W. (1965) Prometryne: Safety 

Evaluation on Fish and Wildlife (Bobwhite Quail, Mallard Ducks, 

Rainbow Trout, Sunfish, Goldfish). (Unpublished study received 

Dec 29, 1977 under 100-542; prepared by Woodard Research 

Corp., submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:232551-B) 

121154 2028304 or 

TN 256 in 

Fed Lab 

Studies

McCann, J. (1970) ?Caparol 80W--Rainbow Trout|: Test No. 256. 

(Unpublished study received Apr 11, 1970 under 100-471; prepared by U.S. Agricultural Research Service, Pesticides Regulation Div., Animal Biology Laboratory, submitted by U.S. Environmental Protection Agency, Beltsville, MD; CDL:129837-A) 

121155 2028305 or 

TN 387 in 

Fed Lab 

Studies

McCann, J. (1971) (Caparol 80W--Bluegill): Test No. 387. 

(Unpub- lished study received Aug 7, 1971 under 100-471; 

prepared by U.S. Agricultural Research Service, Pesticides 

Regulation Div., Animal Biology Laboratory, submitted by U.S. 

Environmental Pro- tection Agency, Beltsville, MD; CDL:129837-

B) 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID DOC# Citation Reference

70146 2028296 Vilkas, A.G. (1977) Acute Toxicity of Prometryn--FL-761355 to the 

Water Flea (~Daphnia magna~Straus): UCES Proj. # 11506-04-

04. (Unpublished study received Dec 29, 1977 under 100-542; 

prepared by Union Carbide Corp., submitted by Ciba-Geigy Corp., 

Greens- boro, N.C.; CDL:232551-D) 

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID DOC# Citation Reference

27094 2028291 Lowe, J.I. (1964) Gulf Shellfish: Effects of Pesticides. (Unpublished study including letter dated Jul 28, 1964 from J.I. Lowe to 

H.E. Fairchild, received Jul 28, 1964 under unknown admin. no.; 

prepared by U.S. Fish and Wildlife Service, Bureau of Commercial Fisheries, submitted by Ciba-Geigy, Greensboro, N.C.; 

CDL:131211-A) 

40228401 SEE GulBreeze Studies Spot, Oyster and Pink Shrimpsupplemental data

40573717 2028310 Surprenant, D. (1988) Acute Toxicity of Prometryn Technical to 

Sheepshead Minnow (Cyprinodon variegatus): Laboratory Study 

No. 87-12-2588. Unpublished study prepared by Springborn Life 
49

Sciences, Inc. 49 p. 

40573718 2028311 Surprenant, D. (1988) Acute Toxicity of Prometryn Technical to 

Mysid Shrimp (Mysidopsis bahia): Laboratory Study No. 88-1-

2601. Unpublished study prepared by Springborn Life Sciences, 

Inc. 52 p. 

40573719 2028312 Surprenant, D. (1988) Acute Toxicity of Prometryn Technical to 

Embryos-larvae of the Quahog Clam (Mercenaria mercenaria): 

Lab- oratory Study No. 88-1-2626. Unpublished study prepared by 

Springborn Life Sciences, Inc. 46 p. 

70147 Wright, L., Jr.; Beliles, R.P. (1966) Prometryne: The Effect on 

Shell Growth in Oysters. (Unpublished study received Dec 29, 

1977 under 100-542; prepared by Woodard Research Corp., submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:232551-E) 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle 

Study

MRID DOC# Citation Reference

24738 2028290 McCann, J.A. (1970) ?Primaze 80W: Toxicity to Rainbow Trout|. 

(U.S. Agricultural Research Service, Pesticides Regulation Div., 

Animal Biology Laboratory, unpublished report.) 

40692 2028295 McCann, J.A. (1970) Primaze 80 W: Bluegill (~?Lepomis macro?-

chirus?~): Test No. 229. (U.S. Agricultural Research Service, 

Pesticides Regulation Div., Animal Biology Laboratory, unpublished study; CDL:129814-A) 

40573720 2028313 Surprenant, D. (1988) The Chronic Toxicity of Prometryn 

Technical to Daphnia magna under Flow-through Conditions: 

Laboratory Study No. 88-1-2622. Unpublished study prepared by 

Springborn Life Sciences, Inc. 79 p. 

40573721 2028314 Humaker, T. (1985) Flow-through Fathead Minnow Early Life 

Stage Toxicity Test with Prometryn: Laboratory Study No. D187. 

Unpublished study prepared by Environmental Research & 

Technology, Inc. 160 p. 

43370403 Response 

to the 

Review

Peters, G. (1994) Response to the Review of: The Chronic 

Toxicity of Prometryn Technical to Daphnia Magna under FlowThrough Conditions. Unpublished study prepared by Ciba Crop 

Protection. 216 p. 

43801702 2028324 Graves, W.; Mank, M.; Swigert, J. (1995) An Early Life-Stage 

Toxicity Test with the Fathead Minnow (Pimephales promelas): 

Prometryn: Lab Project Number: 108A-162. Unpublished study 

prepared by Wildlife International, Ltd. 70 p. 

44031101 See 

43801702 

above

Graves, W.; Mank, M.; Swigert, J. (1996) An Early Life-Stage 

Toxicity Test with the Fathead Minnow, Pimephales promelas: 

Prometryn: A Supplement: Lab Project Number: 108A-162. 

Unpublished study prepared by Wildlife International, Ltd. 11 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable 

Vigor
50

MRID DOC# Citation Reference

40457504 2028307 Cunez, V. (1987) Prometryn Nontarget Phytotoxicity Study: Seed 

Germination/Seedling Emergence Tier 1: Lab Study Number 

LR87-24A2. Unpublished study performed by Pan Agricultural 

Labs. 65 p. 

40457505 2028308 Cunez, V. (1987) Prometryn Nontarget Phytotoxicity Study: 

Vegetative Vigor Tier 1: Study Number LR87-24A1. Unpublished 

study performed by Pan Agricultural Labs. 51 p. 

122-2 Aquatic plant growth

MRID DOC# Citation Reference

40457506 2028309 Hughes, J. (1987) The Toxicity of Prometryn Technical to 

Selenastrum capricornutum: Study Number 0267-38-1100-1. 

Unpublished study performed by Malcolm Pirnie, Inc. 71 p. 

123-1 Seed germination/seedling emergence and vegitative 

vigor

MRID DOC# Citation Reference

41035903 2028317 Canez, V. (1988) Prometryn: Nontarget Phytotoxicity Test: Vegeta- tive Vigor Tier 

II: Study No. LR 88-13A. Unpublished study pre- pared by Pan-Agricultural Labs, 

Inc. 177 p. 

41035904 2028318 Canez, V. (1988) Prometryn: Nontarget Phytotoxicity Test: Seed 

Germination/Seedling Emergence Tier 2: Study No. LR 88-13B. Un- published 

study prepared by Pan-Agricultural Labs, Inc. 228 p. 

123-2 Aquatic plant growth

MRID DOC# Citation Reference

42520901 2028319 Hughes, J.; Alexander, M. (1992) The Toxicity of Prometryn Technical to Laemna 

gibba G3: Lab Project Number: B267-577-4. Unpublished study prepared by 

Malcolm Pirnie, Inc. 36 p. 

42520902 2028320 Hughes, J.; Alexander, M. (1992) The Toxicity of Prometryn Technical to 

Anabaena flos-aquae: Lab Project Number: B267-577-1. Unpublished study 

prepared by Malcolm Pirnie, Inc. 38 p. 

42520903 2028309

2028321

Hughes, J. (1987) The Toxicity of Prometryn Technical to Slenastrum 

Capricornutum: Lab Project Number: 0267-38-1100-1. Unpublished study 

prepared by Malcolm Pirnie, Inc. 73 p. 

42620201 2028322 Hughes, J.; Alexander, M. (1992) The Toxicity of Prometryn Technical to Navicula 

pelliculosa: Lab Project Number: B267-577-2. Unpublished study prepared by 

Malcolm Pirnie, Inc. 35 p. 
51

NON Guideline Listings

21912 Open lit Coupland, R.T.; Skoglund, N.A. (1962) Response of native grasses to various 

herbicides, 1962. Pages 124-125,~In~Research Report for the National 

Weed Committee, Western Section: Volume 9. Edmon- ton, Alberta: Natl. 

Weed Comm.; Pages 84-85,~In~19th Annual Research Report for the North 

Central Weed Control Conference; Dec 3-5, 1962, St. Paul, Minn. N.P. (Univ. of 

Saskatchewan, Dept. of Plant Ecology, Contribution # 340; 

also~In~unpublished submission received Sep 10, 1968 under 876-29; 

submitted by Velsicol Chemical Corp., Chicago, Ill.; CDL:005055-A) 

93171 Open lit Sobieszczanski, J. (1968) The influence of different herbicides upon the growth 

and development of cellulolytic microorganisms. Annales de L'Institut Pasteur 

115(4):113-116. (Also~In~unpub- lished submission received Mar 27, 1972 

under 8F0643; submitted by Stauffer Chemical Co., Richmond, Calif.; 

CDL:095055-AK) 

Ecological Effects Studies Obtained from the ECOTOX Database

Avian Single Dose Oral Toxicity

Ecoref No. Citation Reference

13154 Marchini, S., L. Passerini, D. Cesareo, and M.L. Tosato. 

1988. Herbicidal Triazines: Acute Toxicity on Daphnia, 

Fish, and Plants and Analysis of its Relationships with 

Structural Factors. Ecotoxicol. Environ. Saf. 16(2):148-157

Aquatic plant growth

Ecoref No. Citation Reference

7485 Hawxby, K., Tubea, B., Ownby, J., and Basler, E. (77). Effects of 

Various Classes of Herbicides on Four Species of Algae. 

Pestic.Biochem.Physiol. 7: 203-209.

8628 Liu, L. C. and Cendeno-Maldonado, A. (74). Effects of Fluometuron, 

Prometryne, Ametryne, and Diuron on Growth of Two Lemna Species. 

J.Agric.Univ.P.R. 63: 483-488.

15077 Gaggi, C., Sbrilli, G., El Naby, A. M. H., Bucci, M., Duccini, M., and 

Bacci, E. (95). Toxicity and Hazard Ranking of s-Triazine Herbicides 

Using Microtox, Two Green Algal Species and a Marine Crustacean. 

Environ.Toxicol.Chem. 14: 1065-1069.

61983 Ma, J., Liang, W., Xu, L., Wang, S., Wei, Y., and Lu, J. (2001). Acute 

Toxicity of 33 Herbicides to the Green Alga Chlorella pyrenoidosa. 

Bull.Environ.Contam.Toxicol. 66: 536-541.

62304 Faust, M., Altenburger, R., Backhaus, T., Blanck, H., Boedeker, W., 

Gramatica, P., Hamer, V., Scholze, M., Vighi, M., and Grimme, L. H. 

(2001). Predicting the Joint Algal Toxicity of Multi-Component sTriazine Mixtures at Low-Effect Concentrations of Individual Toxicants. 
52

Aquat.Toxicol. 56: 13-32.

65938 Ma, J., Xu, L., Wang, S., Zheng, R., Jin, S., Huang, S., and Huang, Y. 

(2002). Toxicity of 40 Herbicides to the Green Alga Chlorella vulgaris. 

Ecotoxicol.Environ.Saf. 51: 128-132

71458 Ma, J., Lin, F., Wang, S., and Xu, L. (2003). Toxicity of 21 Herbicides 

to the Green Alga Scenedesmus quadricauda. 

Bull.Environ.Contam.Toxicol. 71: 594-601.

78497 Grossmann, K., Berghaus, R., and Retzlaff, G. (1992). Heterotrophic 

Plant Cell Suspension Cultures for Monitoring Biological Activity in 

Agrochemical Research. Comparison with Screens Using Algae, 

Germinating Seeds and Whole Plants. Pestic.Sci. 35: 283-289.

81431 Drost, W., Backhaus, T., Vassilakaki, M., and Grimme, L. H. (2003). 

Mixture Toxicity of s-Triazines to Lemna minor Under Conditions of 

Simultaneous and Sequential Exposure. Fresenius Environ.Bull. 12: 

601-607.

105114 Liebig, M., Schmidt, G., Bontje, D., Kooi, B. W., Streck, G., 

Traunspurger, W., and Knacker, T. (2008). Direct and Indirect Effects of 

Pollutants on Algae and Algivorous Cilitaes in an Aquatic Indoor 

Microcosm. Aquat.Toxicol. 88: 102-110.

72-2 Acute Toxicity to Freshwater Invertebrates

Ecoref No. Citation Reference

118745 Ralston-Hooper,K., J. Hardy, L. Hahn, H. Ochoa-Acuna, L.S. Lee, R. 

Mollenhauer, and M.S. Sepulveda. (2009). Acute and chronic toxicity of 

atrazine and its metabolites deethylatrazine and deisopropylatrazine on 

aquatic organisms. Ecotoxicology18(7): 899-905.
53

10. APPENDICIES

Appendix A: Prometryn Use and Usage Information

Appendix B: Prometryn Fate and Transport Properties

Appendix C: Output from the SIP and STIR Models

Appendix D: EIIS Incident Report
54

10.1 Appendix A: Prometryn Use and Usage Information

10.1.1 Use Information

Caparol 4L (Registration No. 100-620, Syngenta): Cotton; Carrot, Celeriac, Cilantro, 

(Celery, Chinese celery, Florence fennel), Okra, Parsley, Pigeon Peas (Puerto Rico Only), 

Rhubarb

Suprend Herbicide (Registration No. 100-1163, Syngenta): Cotton

Cotton-Pro (Registration No. 66222-116, Makhteshim Agan): Cotton, Celery, Parsley, 

Prometryn 4 L(Registration No. 66222-15, Makhteshim Agan): carrot, Celeriac, cilantro, 

cotton, dill, leafy petiole (cardoon celery Chinese, celery celtuce, Florence, fennel, 

rhubarb, Swiss chard) okra, parsley, and pigeon peas 

Prometryne 4 L (Registration No. 34704-692, Loveland Products): Cotton, Celery, Dill 

(CA only)

Prometryne 4 L (Registration No. 9779-297, Winfield Solutions): Cotton, Celery

Detailed use information for all registered crops is given below in cotton Tables A-1 to 

A-4.

Table A-1 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds: CaparolTM 4L Herbicide (Registration No. 100-620, Syngenta)

Use Site Soil/Weeds/Crop Restrictions

Application Parameters: MSR and MYR; MNA; MAI (days); Application Methods and 

Others1

MSR MNA MYR MAI Notes & Restrictions

A. Pre-plant 4” Incorporated:

AZ, CA and NM 

only

* Sand and loamy sand soils Do not Apply

* AZ and CA only on sandy loam soils 1.60 1 1.60 N/A Low rate= 1.20 lb a.i/A

* NM only on sandy loam and loam soils 1.60 1 1.60 N/A Only one rate

* AZ, CA and NM only on silt loam and clay soils 2.40 1 2.40 N/A Only one rate

(B) Pre-emergence (At or shortly after crop planting):

(1) Mid-South and 

Southeast*

* Sandy loam 2.00 1 2.00 N/A Low rate= 1.60 lb a.i/A

* Silt and clay loam 2.40 1 2.40 N/A

* AR only on Sharkey clay soils 2.80 1 2.80 N/A

(2) Mississippi

River Delta in MS

* Sandy loam soils 2.40 1 2.40 N/A Low rate= 2.00 lb a.i/A

* Silt and clay loam soils 2.80 1 2.80 N/A

* Sharkey clay soils Do not use

(3) Blacklands**

* Loam soils 1.20 1 1.20 N/A

* Clay soils 2.40 1 2.40 N/A

(4) Rio Grande 

Valley of TX

* Loam soils 1.60 1 1.60 N/A

* Clay soils 2.40 1 2.40 N/A

(5) High/rolling 

Plains and Edwards 

Plateau***

* Sand and loamy sand soils Do not use

For NM , Apply either this application or the Preplant 4” incorporated:, above, Not both

* Sandy loam soils 0.80 1 0.80 N/A

* Loam and sandy clay loam soils 1.20 1 1.20 N/A

Other clay soils 1.60 1 1.60 N/A

(6) AZ and CA Do not use

(7) All Regions Do not use on the following soils: sand or loamy sand , or on shallow soils with caliche below or at soil surface
55

C. Pre-Emergence Reduced Rate Application

Regions 1 to 6, 

above

Sandy loam soils 0.75 1 0.75 N/A A Pre-emergence reduced rate application (At or 

shortly after crop planting) which is to be followed by 

application of other post emergence herbicides usually 

within a period of 30 or more days 

Loam, silt, sandy clay loams & clay loam soils 1.00 1 1.00 N/A

Clay soils 1.00 1 1.00 N/A

D. Winter and Early Spring Weed Control

AL, AR, LA, Mo, 

MS and TN

* After bedding (from November 1 until 14 days 

before planting cotton) 1.00 1 1.00 N/A Only one of the applications Not both and application 

may be made before or after weeds emerge preferably 

<2” high

* After bedding (from January 1 until 30 days 

before planting cotton) 0.75 1 0.75 N/A

E. Winter Weed Control

TX Gulf Coast and 

Black lands of TX

* Winter application for bedded land to be planted 

cotton in the following spring OR

* Fall application for bedded land to be planted 

cotton in the following spring 0.80 1 0.80 N/A

Only one of the applications Not both and application 

may be made before weeds emerge. Low rate= 0..60 lb 

a.i/A

F. Pre-Emergence Or Post-Emergence Winter Application for Bedded Land to be Planted Cotton

California

* Sandy loam soil 1.6 1 1.60 N/A

Pre-emergence Rainfall or sprinkler irrigation is 

necessary

Post-Emergence Apply to weeds less than 2” tall. 

* Medium or fine soil 2.4 1 2.40 N/A

* Sand, loamy sand, salt affected or calcareous soils Do not use

G. Post-Emergence directed

(1) AR, LA, MO, 

MS, TN and TX

Minimum cotton plant Height = 3-6” and maximum 

weed Height= <1” 0.5 1 0.5 N/A

Precautions:

* Prevent contact of the spray with cotton leaves;

* Use precision application equipment so the spray is 

accurately directed to the base of the cotton plants and 

still thoroughly covers the soil and weeds beneath the 

cotton plants (Use leaf lifters or shields);

* Apply only when all cotton plants have exceeded the 

minimum recommended height;

* Apply to level, well prepared surfaces. 

* Do not apply to furrow-planted cotton until furrows 

are leveled (plowed in); and 

* Do not treat cotton under stress

(2) All cotton 

regions

Minimum cotton plant Height = >6” and maximum 

weed Height= <2” 0.7 1 0.7 N/A

H. Chemical Hoe (Emerged weeds only)

All cotton regions

Minimum cotton plant Height = 3-6” 0.5 3 1.5 NS

Precautions:

* In cotton 3-6 inches tall, be

extremely careful to avoid spray contact with cotton 

leaves by applying Caparol

4L with a precision applicator equipped with fenders or 

shields,

* In cotton <10” tall, apply only if cotton is bedded or 

flat-planted.

Minimum cotton plant Height = 3-6” and maximum 

weed Height= <1” 0.7 3 2.1 NS

I. Lay-by application (cotton at least 12” high)

(1) Mid-South and 

Southeast

Sandy soil 1.2 2 2.4 NS

Loam soil 1.4 2 2.8 NS

Clay soil 1.6 2 3.2 NS

(2) Black lands of 

OK and TX

Loam soil 0.8 2 1.6 NS

Clay soil 1.6 2 3.2 NS

(3) High Plains of 

NM and TX

Sandy soil 0.8 2 1.6 NS

Loam and Clay soil 1.2 2 2.4 NS

(4) Southeast TX

Loam soil 1.2 2 2.4 NS

Clay soil 1.6 2 3.2 NS

(5) AZ and CA Sandy Loam and Loam 1.6 2 3.2 NS

(6) All Regions Plant height: cotton >6” and Weeds <2”) 0.65 3 2.0 NS

(7) Rio Grande Valley of TX and Coachella Valley of CA Do not use
56

Table A-2 Use Patterns for Prometryn on cotton for selective control of annual broadleaf 

and grass weeds: Cotton-Pro® (Registration No. 66222-116, Makhteshim Agan); 

Prometryn 4 L(Registration No. 66222-15, Makhteshim Agan); Prometryne 4 L 

(Registration No. 34704-692, Loveland Products), and Prometryne 4 L (Registration No. 

9779-297, Winfield Solutions)

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly rate; ; MAI= Minimum application 

intervals; * Other than the Mississippi River Delta in MS; ** Black lands of OK and TX, TX Gulf Coast, and TX Coastal Bend; *** of TX, Southeast TX and NM 

and KS

Use Site Soil/Weeds/Crop Restrictions

Application Parameters: MSR and MYR; MNA; MAI (days); Application Methods and 

Others1

MSR MNA MYR MAI Notes & Restrictions

(A) Pre-plant (before planting cotton) (Cotton Pro & Prometryn 4L)

(1) Mid-South and 

Southeast, other than 

Mississippi river 

delta in MS

Sandy loam soil 2.0 1 2.0 N/A

Do not use on sand or loamy sand or shallow soils with 

caliche sub-soils or in areas with caliche outcroppings.

Rainfall or irrigation is needed following application to 

obtain weed control

In New Mexico, apply either pre-plant incorporated or 

pre-emergence (not both);

Can be aerially applied

Silt and Clay loam Soil 2.4 1 2.4 N/A

Sharkey clay Do not Use 

(2) Mississippi River 

Delta in MS

Sandy Loam Soil 2.4 1 2.4 N/A

Silt and Clay loam Soil 2.8 1 2.8 N/A

Sharkey clay Do not Use

(3) Black lands of 

TX, OK, TX Gulf 

coast and YTX 

Coastal Bend

Loam soil 1.2 1 1.2 N/A

Clay soil 2.4 1 2.4 N/A

(4) Rio Grande 

Valley of Texas

Loam soil 1.6 1 1.6 N/A

Clay soil 2.4 1 2.4 N/A

(5) High Plains, 

Rolling Plains and 

Edwards Plateau of 

TX, Southwest TX 

and New Mexico

Sandy, Loamy sand Do not Use

Sandy loam soil 0.8 1 0.8 N/A

Loam, sandy clay loam soil 1.2 1 1.2 N/A

Other clay soils 1.6 1 1.6 N/A

(6) AZ and CA Do not use

(B) Pre-plant 4” incorporated (Cotton Pro; Prometryn 4L; Prometryne 4 L/Loveland & Winfield)

(1) AZ, CA and NM Silt loam and clay soil 2.4 1 2.4 N/A Broadcast or band treatment. If broadcast, treat the flat 

soil surface prior to listing. If banded, apply over 

partially finished or finished beds. Incorporate up to 4” 

deep immediately after application. In AZ and CA 

Sandy and loam soils, the Low rate= 1.2. In New 

Mexico, apply either pre-plant incorporated or preemergence (not both); Can be aerially applied; Can be 

aerially applied

Sand and loamy sand soils Do not use

(2) AZ and CA Sandy loam soils 1.6 1 1.6 N/A

(3) NM Sandy loam and loam soils 1.6 1 1.6 N/A

(C) Pre-emergence (at planting or shortly after planting) (Cotton Pro & Prometryn 4L; Prometryne 4 L/Loveland & Winfield)

Regions 1 to 6, Above

Rates and sites are the same as stated for Pre-plant application, above ; except for 

Prometryne 4 L/Loveland formulation that can be used in Sharkey clay soils in AR 

Only

Rainfall or irrigation is needed following preemergence application to obtain weed control. Do not 

apply a second pre-emergence application. If aerially 

applied, avoid spray overlap, as crop injury may result;

Can be aerially applied

Sand or loamy sand, shallow soils with caliche subsoils or in areas with caliche outcroppings Do not Use

(D) Post-emergence Directed: Chemical Hoe (Cotton-Pro; Prometryn 4L; Prometryne 4 L/Loveland & Winfield)

AR, LA, MS, MO, 

TN and TX, and All 

regions

In AR, LA, MS, Mo, TN and TX (Plant height: 

cotton 3-6” and 

Weeds <1”) 0.5 3 1.5 NS

No aerial application. Prevent contact of the spray with 

cotton leaves or injury may occur. Use precision 

application equipment so the spray is accurately 

directed to the base of the cotton plants and still 
57

In All Regions (Plant height: cotton >6” and 

Weeds <2”) 0.65 3 2.0 NS

thoroughly covers the soil and weeds beneath the 

cotton plants. Use leaf lifters or shields. Apply only 

when all plants have exceeded the minimum 

recommended height. Do not apply to furrow-planted 

cotton until furrows are leveled (plowed in). Do not 

treat cotton under stress from drought, cultivator 

damage or fertilizer application

(E) Post-emergence Directed: Lay-By (emerged/germinating weeds) (Cotton-Pro & Prometryn 4L; Prometryne 4 L/Loveland & 

Winfield)

(1) Mid-South and 

Southeast

Sandy soils 1.2 1 1.2 N/A

No aerial application;

When cotton crop is at least 12” tall and weeds<2” tall

Loam soils 1.4 1 1.4 N/A

Clay soils 1.6 1 1.6 N/A

(2) Black lands of TX 

and OK

Loam soils 0.8 1 0.8 N/A

Clay soils 1.6 1 1.6 N/A

(3) High Plains of TX 

and NM

Sandy soils 0.8 1 0.8 N/A

Loam and Clay soils 1.2 1 1.2 N/A

(4) Southwest TX

Loam soil 1.2 1 1.2 N/A

Clay soil 1.6 1 1.6 N/A

(5) Rio Grande Valley of TX Do not Use

(6) AZ and CA (Do 

not use in the 

Coachella valley)

Sand and Loamy sand soils Do not Use

Sandy loam and Loam soils 1.6 1 1.6 N/A

(F) Winter Weed Control (Cotton-Pro)

(1) AR, LA, MS, and 

TX 0.8 1 0.8 N/A Apply in fall or winter to land that will be planted to 

cotton the following spring

Apply before weed emerge or post emergence when 

weeds are <2” tall for most weeds or up to 4-6” tall for 

henbit (purple top). Allow 21 days between this 

(2) CA application and pre-emergence application

Sandy loam soils 1.6 1 1.6 N/A

Medium or Fine soils 2.0 1 2.0 N/A

Sandy and Loamy sand soils Do not Use

(G) Winter Weed Control (Prometryn 4L; Prometryne 4 L/Loveland & Winfield)

(1) AL, AR, LA, MO, 

MS, and TN

Applied after bedding from Nov, 1 until 30 days 

before planting cotton 1.00 1 1.0 N/A

Winter and early spring before or after weeds 

germinate preferably <2” tall.

Applied after bedding from Nov, 1 until 30 days 

before planting cotton 0.75 1 0.75 N/A

(2) TX Gulf coast and 

Black lands of TX

Apply in the fall or winter to land that will be 

planted cotton in the spring 0.8 1 0.8 N/A Fall or winter before weeds reaches 4-6” tall

(2) CA

Sandy loam soils 1.6 1 1.6 N/A

Apply after bedding either pre-emergence or

Post-emergence to weeds less than 2 inches tall

Medium or fine texture soils 2.0 1 2.0 N/A

Sandy and Loamy sand soils Do not Use

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly rate; ; MAI= Minimum application 

intervals;
58

Table A-3 Use Patterns for Prometryn on Other Crops (Ground spray for all crops except 

Pigeon Peas “ground/aerial; Chemigation for applications on celeriac, celery/leafy petiole 

crop groups)

Crop Product

Application Type 

(Site) Soil/Weeds/Crop Restrictions

Application Parameters: MSR and MYR; MNA; MAI (days); Application 

Methods and Others1

MS

R MNA MYR MAI Notes & Restrictions

Carrot

Caparol 4L

And 

Prometryn 

4L

Pre-emergence of 

crop; Plus Not specified 2.0 1 2.0 N/A

Maximum 4 lb a.i./A/crop cycle

Interval NS between the two postemergence applications

Post-emergence of 

crop through the 6 

leaf stage Not specified 1.0 2 2.0 NS

Celeriac

Caparol 4L

Transplants after 

the crop has 6-8 

leaves Or

Coarse textured/low OM soils 0.8 1 0.80 N/A

Maximum 2 lb a.i./A/crop cycle

Fine textured/high OM soils 2.0 1 2.0 N/A

Prometryn 

4L

Post-emergence up 

to 6-8 leaf stage Not specified 2.0 1 2.0 N/A

Celery

Prometryne 

4L 

(Loveland )

To Seedbeds (FL)

Coarse textured/low OM soils 0.6 1 0.60 N/A

Fine textured/high OM soils 0.8 1 0.80 N/A

To Direct seeded 

crop/ Pre crop 

emergence (CA) Or

Coarse textured/low OM soils 1.2 1 1.2 N/A

Fine textured/high OM soils 1.6 1 1.60 N/A

To Direct seeded 

crop/ Post crop 

emergence (CA)

Coarse textured/low OM soils 0.8 1 0.80 N/A

Fine textured/high OM soils 1.0 1 1.0 N/A

Sand or loamy sand soils Do not use

Pre-transplant, 

Split Pre & postTransplant, Or 

Post Transplant 

(CA)

Coarse textured/low OM soils 1.6 1 1.6 N/A

Applications:

(1) Pre-transplant: Up to 21 days prior 

to transplant;

Or

(2) Split Pre & post-transplant: Pretransplant as above plus posttransplant during the 2-6 week period 

after transplanting and weeds <2” tall 

Or

(3) Post-transplant during the 2-6 

week period after transplanting and 

weeds <2” tall 

Maximum pre & post applications 

should not exceed the maximum 

allowable rates stated in the column 

to the left

Fine textured/high OM soils 2.0 1 2.0 N/A

Pre-transplant, 

Split Pre & postTransplant, Or 

Post Transplant 

(FL)

Coarse textured/low OM soils 0.8 1 0.80 N/A

Fine textured/high OM soils 1.6 1 1.6 N/A

Sandy or Muck soils 1.6 1 1.6 N/A

Pre-transplant, 

Split Pre & postTransplant, Or 

Post Transplant 

(HI)

Coarse textured/low OM soils 2.4 1 2.4 N/A

Fine textured/high OM soils 3.2 1 3.2 N/A

Pre-transplant, 

Split Pre & postTransplant, Or 

Post Transplant 

(MI)

Coarse textured/low OM soils 1.0 1 1.0 N/A

Fine textured/high OM soils 2.0 1 2.0 N/A

Muck 2.0 1 2.0 N/A

Pre-transplant, 

Split Pre & postTransplant, Or 

Post Transplant 

(WI)

Coarse textured/low OM soils 1.6 1 1.6 N/A

Fine textured/high OM soils 2.0 1 2.0 N/A

Cotton-Pro;

Prometryne 

4L (Agrisolutions)

To Seedbeds (FL)

Coarse textured/low OM soils 0.6 1 0.60 N/A

Apply 7 days after seed bed covers are 

removed @ 2-5 true leaves celery 

stage

Fine textured/high OM soils 0.8 1 0.80 N/A

Not specified in Prometryne 

4LAgri- solutions Label) 0.8 1 0.80 N/A

To Direct seeded Coarse textured/low OM soils 1.2 1 1.2 N/A Apply at or shortly after planting 
59

crop/ Pre crop 

emergence (CA) Or

Fine textured/high OM soils 1.6 1 1.60 N/A

before crop emerges; Don’t apply if 

crop under water stress. Apply Pre Or 

Post crop emergence Not both

To Direct seeded 

crop/ Post crop 

emergence (CA)

Coarse textured/low OM soils 0.8 1 0.80 N/A

Apply @ 2-5 true leaves celery stage 

and weeds<2” tall. Don’t apply if crop 

under water stress. Weeds <2” tall

Apply Pre Or Post crop emergence 

Not both

Fine textured/high OM soils 1.0 1 1.0 N/A

Sand or loamy sand soils Do not use

To Transplanted 

Crop (CA and TX)

Coarse textured/low OM soils 1.6 1 1.6 N/A

Apply before weeds are 2” tall during 

the 2-6 weeks after planting

Fine textured/high OM soils 2.0 1 2.0 N/A

To Transplanted 

Crop (FL)

Coarse textured/low OM soils 0.8 1 0.80 N/A

Fine textured/high OM soils 1.6 1 1.6 N/A

Sandy or Muck soils 1.6 1 1.6 N/A

To Transplanted 

Crop (HI)

Coarse textured/low OM soils 2.4 1 2.4 N/A

Fine textured/high OM soils 3.2 1 3.2 N/A

To Transplanted 

Crop (MI and OH)

Coarse textured/low OM soils 1.0 1 1.0 N/A

Fine textured/high OM soils 2.0 1 2.0 N/A

Muck 2.0 1 2.0 N/A

(8)To Transplanted 

Crop (WI)

Coarse textured/low OM soils 1.6 1 1.6 N/A

Fine textured/high OM soils 2.0 1 2.0 N/A

Celery, 

Chinese 

celery and 

Florence 

fennel

Caparol 4L 

And 

Prometryn 

4L 

To Seedbeds (FL) All soils 0.8 1 0.80 N/A

After crop has 2-5 true leaves and 7 

days after covers are removed from 

seedbeds

To Direct seeded 

crop/ Pre-crop 

emergence Or

Coarse textured/low OM soils 1.2 1 1.2 N/A At planting or shortly after planting

Do not combine with post crop 

Fine textured/high OM soils 1.6 1 1.60 N/A emergence application

To Direct seeded 

crop/ Post crop 

emergence

Coarse textured/low OM soils 0.8 1 0.80 N/A After crop has 2-5 true leaves and 

before weeds 2” tall

Do not combine with pre- crop 

emergence application

Fine textured/high OM soils 1.0 1 1.0 N/A

Sand and loamy sand soils Do not use

To Transplanted 

Crop (FL) Sandy or muck 1.6 1 1.60 N/A

Apply 2 to 6-week period after 

transplanting

Split application is permitted; however, 

Application intervals were not 

specified (?)

To Transplanted 

Crop (AZ, CA and 

TX)

Coarse textured/low OM soils 1.6 1 1.60 N/A

Fine textured/high OM soils 2.0 1 2.0 N/A

To Transplanted 

Crop (MI and OH) Fine textured or muck 2.0 1 2.0 N/A

To Transplanted 

Crop (WI) Fine textured 2.0 1 2.0 N/A

Cilantro

Caparol 4L

Post-planting /Preemergence of crop

Coarse textured/low OM soils 1.0 1 1.0 N/A

Maximum 1.6 lb a.i./A/crop cycle

Fine textured/high OM soils 1.6 1 1.6 N/A

Prometryn

4L

Post-planting /Preemergence of crop Not specified 1.6 1 1.6 N/A

Dill

Prometryn 

4L And 

Prometryne 

4L 

(Loveland)

Pre-emergence Or Not specified 1.6 1 1.6 N/A

Pre-emergence Or Post-emergence Not 

both. Don’t apply if crop under water 

stress

Post-emergence 

before weeds 2” tall

Not specified. Use on sand or 

loamy sand soils may cause 

crop injury 1.6 1 1.6 N/A

Leafy 

Petiole1 Prometryn 

4L

Seed bed (FL) Not specified 0.8 1 0.80 N/A

After the crop has 2-5 true leaves and 7 

days after seedbed cover is removed

Direct seeded crop 

(CA and AZ) Preemergence Or

Coarse textured/low OM soils 1.2 1 1.2 N/A

Post-emergence= after the crop has 2-5 

true leaves

Fine textured/high OM soils 1.6 1 1.60 N/A

Direct seeded crop 

(CA and AZ) Postemergence

Coarse textured/low OM soils 0.8 1 0.80 N/A

Fine textured/high OM soils 1.0 1 1.0 N/A

Direct seeded crop 

(CA and AZ) Sand and loamy sand soils Do not use

Okra Caparol 4L Pre-emergence Or Not specified 1.5 1 1.50 N/A Pre-emergence= after planting before 
60

10.1.2. Usage Information

Screening Level Usage Analysis (SLUA) for Prometryn

Date: September 10, 2012

What is a Screening Level Usage Analysis (SLUA)?

• Available estimates of pesticide usage data for a particular active ingredient 

that is used on agricultural crops in the United States.

• Pesticide usage data obtained from various sources. The data are then 

merged, averaged, and rounded so that the presented information is not 

proprietary, business confidential, or trade secret. 

What does it contain?

• Pesticide usage data for a single active ingredient only.

• Agricultural use sites (crops) that the pesticide is reported to be used on.

• Available pesticide usage information from U.S. states that produce 80% or 

more of a crop, in most cases, or less than 80%, in rare cases, depending on 

the scope of the survey and available resources.

• Annual percent of crop treated (average & maximum) for each agricultural 

crop.

• Average annual pounds of the pesticide applied for each agricultural crop (i.e., 

for the states surveyed, not for the entire United States).

What assumptions can I make about the reported data?

• Average pounds of active ingredient applied - Values are calculated by 

merging pesticide usage data sources together; averaging across all 

And 

Prometryn 

4L Pre-emergence + 

Post-directed Not specified 0.75 2 1.50

Refer to 

plant 

stage

crop emergence

Post directed= when okra plants are at 

7-9 leaf & weeds 2” tall. Maximum 

1.5/crop cycle. May not be combined

Parsley

Caparol 4L; 

Prometryn 

4L And 

Prometryne 

4L 

(Loveland)

Pre-emergence: 

after planting but 

before crop emerges 

(CA)

Coarse textured/low OM soils 1.0 1 1.0 N/A Do not apply when crop is under water 

Fine textured/high OM soils 2.0 1 2.0 N/A stress

Sandy and loamy sand soils Do not use

Caparol 4L

After planting 

(timing is stated for 

the 1st, 2nd, and 3rd

applications in the 

next column (All 

States including 

CA)

Fine textured/high OM soils

1st

 14 days after planting; 2nd

30-day prior to harvest; 3rd to 

re-growth “after cutting” up 

to 30 days prior to the second 

cutting 0.5 3 1.5

Refer to 

3rd

Column

Use lower rates (specified only for CA 

but not for other states?) in Coarse 

textured/low OM soils

Pigeon 

Peas 

(Puerto 

Rico Only)

Caparol 4L

And 

Prometryn 

4L

Pre-emergence of 

weeds/crop

Loam soils 2.0 1 2.0 N/A

Apply at planting or immediately after 

planting before crop/weeds emerge

Clay soils 3.0 1 3.0 N/A

Sand and loamy sand Do not use

Rhubarb Caparol 4L

To dormant 

established

rhubarb

Coarse textured soils 1.6 1 1.60 N/A Apply before leaves have emerged 

Fine textured soils 2.0 1 2.0 N/A from the crown

Abbreviations: N/A= Not applicable; NS: Not specified, the registrant is requested to supply the information and include it in the label; 

MSR= Maximum Single Rate; MNA= Maximum number of applications; MYR= Maximum yearly (seasonal) rate; MAI= Minimum 

application intervals;

1 Leafy Petiole= cardoon, celery, Chinese celery, celtuce, Florence fennel, rhubarb, and Swiss chard
61

observations, then rounding. Note: If the estimated value is less than 500, 

then that value is labeled <500. Estimated values between 500 & <1,000,000 

are rounded to 1 significant digit. Estimated values of 1,000,000 or greater 

are rounded to 2 significant digits.)

• Average percent of crop treated - Values are calculated by merging data 

sources together; averaging by year, averaging across all years, & rounding to 

the nearest multiple of 5. Note: If the estimated value is less than 2.5, then 

the value is labeled <2.5. If the estimated value is less than 1, then the value 

is labeled <1.

• Maximum percent of crop treated - Value is the single maximum value 

reported across all data sources, across all years, & rounded up to the nearest 

multiple of 5. Note: If the estimated value is less than 2.5, then the value is 

labeled <2.5.

What are the data sources used?

• USDA-NASS (United States Department of Agriculture’s National 

Agricultural Statistics Service) – pesticide usage data from 2003 to 2010.

• Private pesticide market research – pesticide usage data from 2003 to 2010.

• California Department of Pesticide Regulation (DPR) Pesticide Use 

Reporting (PUR) data for 2003 to 2010.

What are the limitations to the data?

• Additional registered uses may exist but are not included because the 

available surveys do not report usage (e.g., small acreage crops).

• Lack of reported usage data for the pesticide on a crop does not imply zero 

usage.

• Usage data on a particular site may be noted in data sources, but not 

quantified. In these instances, the site would not be reported in the SLUA.

• Non-agricultural use sites (e.g., turf, post-harvest, mosquito control, etc.) are 

not reported in the SLUA. A separate request must be made to receive these 

estimates.

• Some sites show some use, even though they are not on the label. This usage 

could be due to various factors, including, but not limited to Section 18 

requests, existing stocks of the chemical, data collection errors, and 

experimental use permits (EUPs). 
62

 

September 10, 2012

Screening Level Estimates of Agricultural Uses of Prometryn (080805)

Sorted Alphabetically

Reporting Years: 2003-2010

Percent Crop Ttd.

Crop Lbs. A.I. Avg. Max.

1 Carrots 3,000 <2.5 <2.5

2 Celery 40,000 85 100

3 Cotton 800,000 10 15

4 Fallow 3,000 <1 <2.5

All numbers are rounded.

 <2.5: indicates less than 2.5 percent of crop is treated.

 <1: indicates less than 1 percent of crop is treated.

SLUA data sources include: 

USDA-NASS (United States Department of Agriculture's National Agricultural Statistics Service) 

Private Pesticide Market Research

These results reflect amalgamated data developed by the Agency and are releasable to the public.
63

10.2 Appendix B: Prometryn Fate and Transport Properties

Laboratory fate and transport properties of prometryn are summarized in following 

Tables:

Fate properties of prometryn in biotic systems in the laboratory

Property

Soil or Water/Sediment 

System* Degradation Products (% of Applied) Value

Reference (MRID)

Classification

Aerobic Soil 

Metabolism 1

Loamy Sand soil 

(Germany): 84% sand, 

7% silt, 9% clay, 2.2% 

organic carbon, pH 6.5, 

CEC 11.3 meq/100 g

Major (MAJ): GS-11526 (max. 27% @ 

termination (360 days); 

Minor (MIN): GS-11354 (max. 5% @ day 

60 then declined to 1% @ termination (360 

days); 

Mineralization (MRL): CO2 (max. 0.5% 

@ termination); 

Non-extractable residues (NER): max. 

31% @ termination 257 days

001483-38

Acceptable

Aerobic 

Aquatic 

Metabolism 

(total system)

River System: Water:

pH 8, OC 3 ppm. 

Sediment: 25% sand, 

57% Silt and 18% clay, 

OC 3.7% and CEC= 21

MAJ: GS-11526 (max. 18% @ termination 

(268 days); 

MIN:

GS-11354 (max. 3% @ 58 days then 

declined to 1.3% @ termination 

GS-16141 (max. 7% @ 58 days then 

declined to 6% @ termination

GS-17794 (max. 4% @ termination 

MRL: CO2 (max. 0.5% @ termination); 

NER: max. 26% @ termination 236 days

485416-03

Under Review2

Aerobic 

Aquatic 

Metabolism 

(total system)

Pond System: Water:

pH 7.4, OC 5 ppm. 

Sediment: 46% sand, 

43% Silt and 12% clay, 

OC 1.5% and CEC= 10

MAJ: GS-11526 (max. 18% @ termination 

(268 days); 

MIN:

GS-11354 (max. 3% @ 91 days then 

declined to 0.6% @ termination 

GS-16141 (max. 6% @ 58 days then 

declined to 2.8% @ termination

GS-17794 (max. 5% @ termination 

MRL: CO2 (max. 0.4% @ termination); 

NER: max. 35% @ termination 110 days

485416-03

Under Review2

Anaerobic soil 

metabolism 

half-life (25 

°C)

Sandy loam soil 

(California): 60% sand, 

35% silt, 5% clay, 0.7% 

organic carbon, pH 4.6, 

CEC 3.4 meq/100 g

Samples were aerobically pre-incubated for 

30 days and levels of parent and unextractable residues were determined before 

the anaerobic incubation step for 71 days: 

Parent and un-extractable residues were 

practically stable throughout the 71 days 

with No degradation products formed. Stable

411559-01

Acceptable

1 Incomplete material balance invalidated the anaerobic portion of the study;

2 Under Review: Formal review underway.
64

Transport properties of prometryn

Property

Soil or Water/Sediment 

System* Degradation Products (% of Applied) Value

Reference (MRID)

Classification

Soil-water 

partition 

coefficients 

(KFOC) L/Kg

Agricultural 

sand/Huntington Si L 

(88% sand, 11% silt, 1% 

clay, 3 meq/100g CEC, 

pH 7.9, and 0.6% 

Organic matter N/A

Parent 245

418759-01/03

Acceptable

GS-11354 174

GS-11526 186

Loamy sand/ 

Huntington Si L (84% 

sand, 13% silt, 3% clay, 

7 meq/100g CEC, pH 

7.7, and 1.7% Organic 

matter N/A

Parent 169

GS-11354 86

GS-11526 85

Silt Loam/ Amour Si L 

(17% sand, 66% silt, 

17% clay, 16 meq/100g 

CEC, pH 6.5, and 3.0% 

Organic matter N/A

Parent 116

GS-11354 72

GS-11526 84

Silty clay loam/Salvisa 

Si C L (15% sand, 51% 

silt, 34% clay, 30 

meq/100g CEC, pH 6.9, 

and 1.2% Organic 

matter N/A

Parent 448

GS-11354 210

GS-11526 1,044

Laboratory 

Volatility at 25 

o

C

Sandy soil (88% sand, 

11% silt, 1% clay, 

0.62% organic matter, 

pH 7.9, CEC= 3 

meq/100 g)

* Mean daily air concentration of 14C 

prometryn ranged from 0.41 to 0.97 ug/m3;

* Volatility rates ranged from 9.2 x 10-5 to 

1.1 x 10-4 ug/cm2

/hr 

* Minimal volatility: an average of 0.99% 

(mean, N = 4) of the applied prometryn 

volatilized from the soil during the 30 day 

incubation period

418759-06

Acceptable

Fish bioconcentration 

and depuration Bluegill sunfish

BCFs: 85x (whole fish)

 54x (fillet)

 110x (viscera)

73% depuration in whole fish after 14 days

410227-01 

Acceptable
65

Terrestrial field studies for prometryn

Location Top Soil Characteristics 

Degradation Products (% of Applied)

and Leaching

PDHL 

(Days)1

Reference (MRID)

Classification

Terrestrial 

field 

dissipation

(CA planted 

cotton)

- Sandy loam soil: 70% 

sand, 18% silt, 12% clay, 

0.9% OM, pH 7.4, CEC 

8.4 meq/100 g 

- Planted cotton: 

Application Rate (total= 

7.8 lbs a.i/A): five weekly 

applications @ 0.7 to 3.1 

a.i/A/Application

- Bare ground:

Application Rate: one 

application of 6.5 lbs a.i/A

Degradation Products

GS-11526 (max. 23% @ 7 days then 

declined to 2% @ termination (>1 year); 

GS-11354 (max. 3% @ 7 days then 

declined to 1% @ termination 

Leaching

Parent: refer to summary below

GS-11526:

15-60 cm layer: Detected 6 to 13% of the 

time @ a maxi. concentration of 4%

60-120 cm layer: Detected 13% of the time 

@ concentrations ranging from 1 to 5%

GS-11354: Was not detected below 15 cm 103

415464-01

supplemented with

422539-03

Acceptable

Terrestrial 

field 

dissipation

(CA bare soil)

Degradation Products

GS-11526 (max. 15% @ 2-3 months then 

declined to ND @ termination (>1 year); 

GS-11354 (max. 1% throughout the study 

period then declined to ND @ termination 

Leaching

Parent: refer to summary below

GS-11526:

15-60 cm layer: Detected 3 to 100% of the 

time @ a maxi. Concentration of 5%

60-120 cm layer: Was not detected

GS-11354: Was not detected below 15 cm 71

415464-02

supplemented with

422539-04

Acceptable
66

Prometryn and its major/minor environmental transformation products

PARENT: Prometryn: N,N'-diisopropyl-6-rnethyIsulfanyl-[1,3,5]triazine-2,4-diamine

Smiles: C1(=NC(=NC(=N1)NC(C)C)SC)NC(C)C; CAS No.: 7287-19-6

MAJOR TRANSFORMATION PRODUCTS

Name (Code & Synonym)/ Formula/Molecular Weight (MW)

CAS No./Smiles Codes Study Type (MRID) Maximum %Applied Radioactivity “AR” (day) And % AR Following Maximum (day of Occurrence)

Hydroxypropazine (GS-11526): 4,6-bisisopropylamino-[1,3,5]triazine-2-ol

Formula: C9H17N5O

MW: 211.26 g/mol; CAS No.: 7374-53-0

Smiles:C1(=NC(=NC(=N1)NC(C)C)O)NC(C)C

Aerobic soil (001483-38) 27% @ 365 days with no decline

Aerobic aquatic (485416-03) 16-18% @ 268 days with no decline

TFD (415464-01/04 

Supplemented w/ 422539-01/04)

15-31% @ 14-90 days then declined to 

No detection -1% @ 540-544 days

MINOR TRANSFORMATION PRODUCTS

Prometryn Sulfoxide ( GS-16141): 4,6-bisisopropylamino-2-methanesulfinyl-[1,3,5] triazine

Formula: C10H19N5SO

MW: 257.36 g/mol; CAS No.: 55702-48-2

Smiles:C1(=NC(=NC(=N1)NC(C)C)[S](C)=O)NC(C)C

Aerobic soil (001483-38) Not Tracked Not Tracked

Aerobic aquatic (485416-03)

6-7% @ 58 days then declined to 3-6 % 

@ 268 days

TFD (415464-01/04 

Supplemented w/ 422539-01/04) Not detected Not detected

Terrestrial 

field 

dissipation

(TX planted 

cotton)

- Silt loam soil: 18% sand, 

64% silt, 18% clay, 2.1% 

OM, pH 7.7, CEC 13.4 

meq/100 g 

- Planted cotton: 

Application Rate (total= 

6.0 lbs a.i/A): five weekly 

applications @ 0.5 to 3.1 

a.i/A/Application

- Bare ground:

Application Rate: one 

application of 7 lbs a.i/A

Degradation Products

GS-11526 (max. 31% @ 14 days then 

declined to 1% @ termination (>1 year); 

GS-11354 (max. 4% @ 7 days then 

declined to 1% @ termination 

Leaching

Parent: refer to summary below

15-60 cm layer: Detected 10 to 17% of the 

time @ a maxi. Concentration of 4%

60-120 cm layer: Was not detected

GS-11354: Was not detected below 15 cm 86

415464-03

supplemented with

422539-01

Acceptable

Terrestrial 

field 

dissipation

(TX bare 

ground)

Degradation Products

GS-11526 (max. 15% @ 2-3 months then 

declined to ND @ termination (>1 year); 

GS-11354 (max. 1% throughout the study 

period then declined to ND @ termination 

Leaching

Parent: refer to summary below

15-60 cm layer: Detected 10 to 12% of the 

time @ a maxi. Concentration of 2%

60-120 cm layer: Was not detected

GS-11354: Was not detected below 15 cm

Parent Leaching(All studies summary):

15-60 cm layer: Detected 3 to 100% of the 

time @ concentrations ranging from 2 to 5%

60-120 cm layer: Detected 13% of the time 

@ concentrations ranging from 1 to 5% 70

415464-04

supplemented with

422539-02

Acceptable

1 PDHL= Parent Dissipation Half-life: Half-lives for the top 15 cm of the soil were calculated using linear regression; these halflives will be recalculated using non-linear models; ND= No detection
67

Des-ethylhydroxy atrazine (GS-17794): 4 arnino6-isopropylarnino-(1,3,5jtriazine-2-ol) 

Formula: C6H11N5O

MW: 169.19 g/mol; CAS No.: Not reported

Smiles:C1(=NC(=NC(=N1)NC(C)C)O)N

Aerobic soil (001483-38) Not detected Not detected

Aerobic aquatic (485416-03) 4-5% @ 268 days with no decline

TFD (415464-01/04 

Supplemented w/ 422539-01/04) Not detected Not detected

De-isopropyl prometryn (GS-11354), de-alkyed 

prometryn Or De-metylametryn): N-lsopropyl-6-

methylsuIfanyl-[1,3,5]triazine-2,4-diamine) 

Formula: C7H13N5S

MW: 199.28 g/mol; CAS No.: Not Reported

Smiles:C1(=NC(=NC(=N1)NC(C)C)N)SC

Aerobic soil (001483-38) 1% @ 365 days with no decline

Aerobic aquatic (485416-03)

3% @ 58 0r 91 days then declined to 1% 

@ 268 days

TFD (415464-01/04 

Supplemented w/ 422539-01/04)

1-4% @ 7 days then declined to 0-1% at 

540-544 days
68

10.3 Appendix C: Output from the SIP and STIR Models

1. Output from the Screening Imbibition Program (SIP)

Table 1. Inputs

Parameter Value

Chemical name Trifloxystrobin

Solubility (in water at 25oC; mg/L) 0.61

Mammalian LD50 (mg/kg-bw) 5000

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 50

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Avian LD50 (mg/kg-bw) 5000

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 5050

Bobwhite quail NOAEC (mg/kg-diet) 5050

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird 

species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.1049 0.1049

Adjusted toxicity value (mg/kg-bw) 3845.8028 38.4580

Ratio of exposure to toxicity 0.0000 0.0027

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals
69

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.4941 0.4941

Adjusted toxicity value (mg/kg-bw) 3602.1476 250.5434

Ratio of exposure to acute toxicity 0.0001 0.0020

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of 

exposure. Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), 

pesticide exposure through drinking water may contribute to a total exposure that has 

potential for effects to non-target animals.

2. Output from the Screening Tool for Inhalation Risk (STIR)

Input

Application and Chemical Information

Enter Chemical Name Prometryn

Enter Chemical Use All

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 241.4

Enter Chemical Vapor Pressure (mmHg) 1.60E-06

Enter Application Rate (lb a.i./acre) 4

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 4640

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 1802

Enter Lowest Rat Inhalation LC50 (mg/L) 4.96

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.08E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.61E-03

Adjusted Inhalation LD50 7.12E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.67E-05 Exposure not Likely 
70

Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.84E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 5.40E-03

Exposure not Likely 

Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.08E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.28E-03

Adjusted Inhalation LD50 2.95E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.11E-05

Exposure not Likely 

Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.83E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 1.64E-03

Exposure not Likely 

Significant
71

10.4 Appendix D: EIIS Incident Report

EIIS Pesticide Summary Report: General Information Prometryn 

(080805)

Incident # Date County State Certainty Legal.

Formul. Appl. MethodTotal Magnitude

AQUATIC

Cotton

I004021-005 8/6/1996 Richland LA 1 UN

I004021-004 8/6/1996 RICHLAND LA 1 RU

I004668-011 8/7/1996 RICHLAND LA 1 RU

PLANTS

Corn

I019130-056 7/31/2007 New Madrid MO 3 UN Broadcast

COTTON

I007796-006 8/17/1998 HALE TX 2 UN N/R 

I007796-005 8/25/1998 HALE TX 2 UN N/R 

I009573-014 11/12/1999 CALDWELL TX 3 RU F Broadcast 

I016903-008 7/21/2005 Uvalde TX 2 RU

EC Band 60 acres cotton

I016903-009 9/8/2005 Evans GA 2 RU

EC Band 26 acres cotton

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Incident # Species Scientific Name Magnitude Response Rt. Exposur

AQUATIC

COTTON

I004021-004

carp Cyprinus carpio thousands mortality

shad Clupeidae 25 mortality

I004021-005

buffalo Catostomidae hundreds mortality

shad Clupeidae thousands mortality

I004668-011

buffalo Catostomidae hundreds mortality

gar Lepisosteus spp. hundreds mortality

shad Clupeidae hundreds mortality

PLANTS

Corn

I019130-056

corn Zea mays 86 acres plant damag

COTTON

I007796-005

cotton Gossypium all 600 acres mortality

I007796-006

cotton Gossypium all 1424 acres mortality

I009573-014

cotton Gossypium 70% of 58 acres plant damag

I016903-008

cotton Gossypium 60 acres plant damag

I016903-009

cotton Gossypium 26 acres plant damag

Tuesday, October 09, 2012 Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable.

Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse 

(Intentional), U=Unknown.

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