2

Several data gaps have been identified in association with a review of registrant-submitted 

studies to fulfill guideline requirements. Submission of data to eliminate data gaps would reduce 

uncertainties in the exposure assessment. Data gaps have been assigned either a low or high 

potential to add value to the Registration Review risk assessment. While still considered data 

gaps according to 40 CFR Part 158, low potential studies are unlikely to change risk 

determinations because alternate methods and weight of evidence may possibly be used in the 

absence of data. High potential studies would enable the Agency to better characterize potential 

risks by eliminating exposure uncertainties that cannot be accounted for using alternate methods 

or weight of evidence.

Data from the following guideline studies are considered to have high potential to add value to 

the ecological risk assessment for prometon:

Guideline 835.4300 – Aerobic Aquatic Metabolism: Data for aerobic aquatic metabolism are 

required under 40 CFR Part 158. Given that the 2008 RED (DP 335306) identified a risk 

concern for aquatic organisms, fulfilling this data requirement has a high potential to add value 

to the Registration Review ecological risk assessment.

Guideline 835.4400 – Anaerobic Aquatic Metabolism: Data for anaerobic aquatic metabolism

are required under 40 CFR Part 158. Given that the 2008 RED (DP 335306) identified a risk 

concern for aquatic organisms, fulfilling this data requirement has a high potential to add value 

to the Registration Review ecological risk assessment.

Guideline 850.1075 – Fish Acute Toxicity, fathead minnow or Guideline 850.1400 – Fish 

Early Life Stage Toxicity Test, rainbow trout: The chronic, early life stage endpoint of 19.7 

mg/L for freshwater fish (fathead minnow; MRIDs 41810902, 42318202) is approximately equal 

to the most sensitive acute endpoint of 19.6 mg/L for freshwater fish (rainbow trout; MRID 

41609108). This discrepancy is probably due to the different species used in the tests (i.e., 

fathead minnow in the chronic test and rainbow trout in the acute test). Additional data – either 

an acute toxicity test with fathead minnow or a chronic test with rainbow trout – are 

recommended and considered to have a high potential to add value to the Registration Review 

risk assessment because the data will allow the Agency to evaluate risk to freshwater fish species 

as well as generate an acute to chronic ratio (ACR) for evaluating risk to estuarine/marine fish 

species from chronic exposure. 

Guideline 850.2100 – Avian Oral Toxicity, passerine species: Acute oral toxicity data for a 

passerine species are required under the new 40 CFR Part 158. No studies have been submitted 

for this data requirement. Given that the 2008 RED (DP 335306) identified a risk concern for 

birds from acute and chronic exposure, fulfilling this data requirement has a high potential to add 

value to the Registration Review ecological risk assessment as the generated data will allow us to 

be protective of passerine species.

Guideline 850.4400 – Aquatic Plant Toxicity Test Using Lemna spp.: Data for an aquatic 

vascular species (Lemna spp.) are required under 40 CFR Part 158. In previous risk assessments, 
3

an ECOTOX open literature study (E081431) was referenced for characterizing the toxicity of 

prometon to aquatic vascular plants (i.e., Lemna spp.). However, this study has been classified 

as qualitative for use in the Registration Review ecological risk assessment because of the lack 

of experimental details (e.g., replication, test concentrations). Given that the 2008 RED (DP 

335306) identified a risk concern for aquatic vascular plants, fulfilling this data requirement has 

a high potential to add value to the Registration Review risk assessment.

Guideline 850.4500 – Algal Toxicity & Guideline 850.4550 – Cyanobacteria (Anabaena flosaqua) Toxicity: Data for aquatic non-vascular plant species are required under 40 CFR Part 158. 

No studies have been submitted for a freshwater diatom (e.g., Navicula pelliculosa), a marine 

diatom (e.g., Skeletonema costatum), or a cyanobacterium (e.g., Anabaena flos-aqua). In 

previous risk assessments, an ECOTOX open literature study (E009211) was referenced for 

characterizing the toxicity of prometon to marine algae. However, this study has been classified 

as qualitative for use in the Registration Review ecological risk assessment because of the lack 

of experimental details (e.g., replication, test concentrations). Given that the 2008 RED (DP 

335306) identified a risk concern for aquatic non-vascular plants, fulfilling this data requirement 

has a high potential to add value to the Registration Review risk assessment.
4

REGISTRATION REVIEW

PROBLEM FORMULATION

Prometon

CAS Number 1610-18-0

US EPA PC CODE 080804

Prepared by:

Robin Sternberg, Ph.D., Wildlife Biologist 

Stephen Wente, Ph.D., Biologist

Environmental Risk Branch I

Reviewed by:

Faruque Khan, Ph.D., Senior Fate Scientist

Sujatha Sankula, Ph.D., Lead Biologist

Environmental Risk Branch 1

Rueben Baris, M.S., Environmental Scientist

Environmental Risk Branch 4

Frank Farruggia, Ph.D., Biologist

Environmental Risk Branch 3

Environmental Fate and Effects Division

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

N

N

N

OCH3

N N

CH3

CH3

H3C

CH3
5

Contents

1 Introduction............................................................................................................................. 6

2 Previous Assessments............................................................................................................. 6

3 Overview of Prometon Use..................................................................................................... 7

4 Environmental Fate Summary ................................................................................................ 8

5 Ecological Effects Summary................................................................................................. 10

5.1 Parent: Prometon............................................................................................................ 10

5.2 Prometon Degradates ..................................................................................................... 14

5.2.1 ECOSAR-Predicted vs. Observed Toxicity Endpoints for Parent Prometon ......... 15

5.2.2 GS-11526 ................................................................................................................ 15

5.2.3 GS-14626 and GS-17794........................................................................................ 17

5.2.4 GS-12853 and GS-17791........................................................................................ 17

5.2.5 Summary of Degradate Toxicity............................................................................. 17

5.3 Review of Incident Databases........................................................................................ 17

6 Risk Hypothesis.................................................................................................................... 18

7 Exposure Pathways of Concern ............................................................................................ 18

8 Analysis Plan ........................................................................................................................ 19

8.1 Stressors of Concern....................................................................................................... 19

8.2 Measures of Exposure .................................................................................................... 19

8.3 Measures of Effect ......................................................................................................... 20

8.4 Integration of Exposure and Effects............................................................................... 20

8.5 Drinking Water Assessment........................................................................................... 20

8.6 Endangered Species Assessments.................................................................................. 21

8.7 Endocrine Disruptor Screening Program ....................................................................... 21

9 Data Gaps.............................................................................................................................. 22

9.1 Environmental Fate Data................................................................................................ 22

9.2 Ecological Effects Data.................................................................................................. 24

10 References............................................................................................................................. 29

11 Bibliography of Cited MRIDs .............................................................................................. 29

Appendix A: SIP (v 1.0) Inputs and Results................................................................................. 36
6

1 Introduction

The purpose of this problem formulation is to provide an understanding of the environmental fate 

and ecological effects of the registered uses of prometon in support Registration Review.

Prometon is a non-selective triazine herbicide labeled for pre- and post-emergence applications 

to sites that require total control of vegetation (i.e., annual and perennial grasses and broadleaf 

weeds) resulting in bare ground for one and two years after a single application. There are no 

agricultural uses for prometon. Non-agricultural uses of prometon include weed control as a spot 

treatment around buildings, storage areas, fences, pumps, machinery, fuel tanks, recreational 

areas, guard rails, airports, military installations, highway medians, pipelines, railroads, 

lumberyards, rights-of-way, and industrial sites (such as transformers, vaults, buried cable 

closures)1. The 2008 Reregistration Eligibility Decision (RED) for prometon specified that all 

residential use of prometon was to be cancelled. On January 2, 2012 the Agency published in the 

Federal Register (FR Vol. 78, No.1) a notice of receipt of requests for an amendment to delete all 

residential uses of prometon on registered labels. The mechanism of action of prometon 

involves inhibition of photosynthesis via disruption of CO2 fixation and production of 

intermediary energy components (e.g., ATP and NADPH2) leading to plant death.

2 Previous Assessments

An ecological risk assessment for registered uses was conducted as part of prometon’s 2008 

RED (DP 335306). The RED did not require any additional environmental fate or ecological 

effects studies.

The RED assessment identified risk to: 

• birds and mammals from acute and chronic exposure. Risk to both taxa from acute 

exposure via spray drift was estimated to drop below levels of concern approximately 10 

feet away from the treated site. Risk from chronic exposure was estimated to extend as 

far away from the treated site as 70 ft for birds and 1000 ft for mammals.

• non-target terrestrial plants, both monocots and dicots, from spray drift and runoff. Risk 

from spray drift was estimated to extend up to 1000 ft from the treated site for ground or 

truck-mounted sprayers.

• listed aquatic animals from acute exposure for some modeling scenarios.

• aquatic non-vascular and vascular plants.

The RED determined that prometon was eligible for reregistration provided several risk 

mitigation measures and label amendments were adopted.

Mitigation measures and label amendments to address non-target terrestrial exposures to animals 

and plants, including spray drift, were as follows:

• The maximum use rate is reduced to 16 lbs a.i./A for applications under block or solid 

paving. 

• The maximum use rate is reduced to 18 lbs a.i./A for all other industrial sites. 

 1 Per BEAD memo dated October 11, 2012
7

• End-use product labels will include language requiring that weeds greater than 4 inches 

must be mowed, removed, or hoed into the soil prior to application. 

• End-use product labels will include language requiring that immediately after application, 

treatment areas must be watered in with at least 1/4” of water or treatments will be made 

just prior to a rain event. 

• Applications must be made using medium- to coarse-sized droplets.

• Applications must not be made to sloped areas where desirable vegetation or adjacent 

water bodies are located downhill of the treatment area.

• Products containing prometon are limited to one application per year.

A litigation assessment for the federally-listed Barton Springs salamander (Eurycea sosorum) 

was conducted in 20072

. This assessment concluded that use of prometon in the Barton Springs 

Segment of the Edwards Aquifer (BSSEA) may have the following effects: no effect based on a 

total yearly usage of <1,650 lbs ai; may affect, not likely to adversely affect (indirect) based on

total yearly usage of ≥1,650 lbs ai but <22,000 lb ai; and may affect, likely to adversely affect 

(direct) based on total yearly usage of ≥22,000 lbs ai.

A drinking water assessment was performed for all uses of prometon on October 24, 2007 based 

on modeling and monitoring data. Prometon degradation products were not considered in this 

drinking water assessment. Tier II PRZMIEXAMS modeling indicate prometon concentrations 

in surface source drinking water were not expected to exceed 92 μg/L for the 1 in 10 year annual 

peak concentration, 70 μg/L for the 1 in 10 year annual average concentration, and 44 μg/L for 

the 30 year annual average concentration. Non-targeted surface water monitoring program 

indicated a maximum observed prometon concentration of 25 μg/L. The maximum average 

prometon concentration for a sampling site was 3.03 μg/L. Tier I SCI-GROW modeling 

predicted peak and chronic prometon concentrations in shallow groundwater of 706 μg/L. Nontargeted ground water monitoring data indicated a maximum observed prometon concentration 

of 40 μg/ L based on a 59.98 lbs ai/A application rate and 236 ug/L based on a 20.04 lbs ai/A 

application rate.

3 Overview of Prometon Use

Prometon is registered for weed control at the following use sites: agricultural/farm 

structures/buildings and equipment, airports/landing field, commercial/institutional/industrial 

premises/equipment (outdoor), commercial storage/warehouse premises, fencerows/hedgerows, 

industrial/construction areas (outdoor), nonagricultural outdoor buildings/structures, 

nonagricultural rights-of-way/fencerows/ hedgerows, nonagricultural uncultivated areas/soils, 

paved roads (private roads/sidewalks), recreational areas, and utility poles/rights-of-way. 

Prometon is formulated as an emulsifiable concentrate, liquid, or pellet/tablet and is applied once 

per year via ground broadcast, ground spray, or sprinkle can at a maximum single application 

rate of 9.1 lb a.i./A for rights-of-way specifically for utility poles and 18 lb a.i./A for all other use 

sites (including other types of rights-of-way).

 2 http://www.epa.gov/oppfead1/endanger/litstatus/effects/#prometon
8

Based on usage information provided by the registrant, total annual sales of prometon are 

approximately 550,000 - 600,000 pounds of a.i.: approximately 60% is applied to building 

perimeters or fencerows; 30% is applied to industrial sites; and <1 0% is applied to rights-of-way 

areas3.

4 Environmental Fate Summary

Prometon is persistent and mobile in the environment. Leaching and runoff are expected to be 

important transport pathways for prometon (water solubility of 720 mg/L), while volatilization is 

not (vapor pressure of 7.73 × 10-6). Probable routes of dissipation from the use site are through 

runoff into surface water and leaching into groundwater. Prometon is stable to abiotic hydrolysis

and photodegradation in water and soil. Half-lives of prometon range from 462 to 932 days in 

aerobic soil (study durations of 365 and 368 days). In anaerobic soil, the half-life is 557 days

(study duration of 120 day: 30 aerobic and 90 anaerobic). Aerobic and anaerobic aquatic 

metabolism data are not available for this chemical. Degradation products of are shown in Table 

4-1.

Table 4-1. Structures and Basic Chemistry and Mobility Data for Prometon and Prometon 

Degradates Identified in Registrant-Submitted Fate Studies

Prometon (Parent)

Prometon

Formula: C10H19N5O

Molecular Weight: 225.30

Smiles Code: O(c(nc(nc1NC(C)C)NC(C)C)n1)C

Water Solubility: 750 mg/L (25oC) (Tomlin, C. 1994)

Koc: 137.4 L/kg (EPI Suite MCI method)

Prometon Degradates in Registrant-submitted Fate Studies

Prometon degradate GS-14626

Formula: C7H13N5O

Molecular Weight: 183.21

Smiles Code: O(c(nc(nc1NC(C)C)N)n1)C

Water Solubility: 836.3 mg/L (25oC) (EPI Suite WSKOW v1.41)

Koc: 42.09 L/kg (EPI Suite MCI method)

Maximum % Formationa

Aerobic Soil Metabolism – 15.4% (increasing at study end: 368 days)

Anaerobic Soil Metabolism – 5.3%

Terrestrial Field Dissipation – 1.3 ppm

Prometon degradate GS-11526b

Synonym: 2-hydroxypropazine

CAS no.: 7374-53-0

Formula: C9H17N5O

Molecular Weight: 211.27

Smiles Code: O(c(nc(nc1NC(C)C)NC(C)C)n1)

Water Solubility: 275.3 mg/L (25oC) (EPI Suite WSKOW v1.41)

Koc: 275.5 L/kg (EPI Suite MCI method)

 3 Per BEAD memo dated October 11, 2012

N

N

N

OCH3

N N

CH3

CH3

H3C

CH3

N

N

N

OCH3

N NH2

H3C

CH3

N

N

N

OH

N N

CH3

CH3

H3C

CH3
9

Maximum % Formationa

Aerobic Soil Metabolism – 8.5% (increasing at study end)

Anaerobic Soil Metabolism – 0.4%

Terrestrial Field Dissipation – NA

Prometon degradate GS-12853

Formula: C4H7N5O

Molecular Weight: 141.13

Smiles Code: O(c(nc(nc1N)N)n1)C

Water Solubility: 22,850 mg/L (25oC) (EPI Suite WSKOW v1.41)

Koc: 12.89 L/kg (EPI Suite MCI method)

Maximum % Formationa

Aerobic Soil Metabolism – 0.32% (increasing at study end: 326 days)

Anaerobic Soil Metabolism – 0.07% (increasing at study end: 92 days)

Terrestrial Field Dissipation – 0.16 ppm

Prometon degradate GS-17794c

Synonyms: desethyl-2-hydroxy-atrazine; deethylhydroxyatrazine; OIAT/ 

DHEA

CAS no.: 19988-24-0

Formula: C6H11N5O

Molecular Weight: 169.19

Smiles Code: O(c(nc(nc1N)NC(C)C)n1)

Water Solubility: 7818 mg/L (25oC) (EPI Suite WSKOW v1.41)

Koc: 84.38 L/kg (EPI Suite MCI method)

Maximum % Formationa

Aerobic Soil Metabolism – 0.61% (increasing at study end: 326 days)

Anaerobic Soil Metabolism – 0.16% (increasing at study end: 92 days)

Terrestrial Field Dissipation – NA

Prometon degradate GS-17791d

Synonyms: Ammeline, desethyl-desisopropyl-2-hydroxy-atrazine (DIH)

CAS No.: 645-92-1

Formula: C3H5N5O

Molecular Weight: 127.11

Smiles Code: O(c(nc(nc1N)N)n1)

Water Solubility: 208,300 mg/L (25oC) (EPI Suite WSKOW v1.41)

Koc: 25.84 L/kg (EPI Suite MCI method)

Maximum % Formationa

Aerobic Soil Metabolism – 0.13% (increasing at study end: 326 days)

Anaerobic Soil Metabolism – 0.01% (increasing at study end: 92 days)

Terrestrial Field Dissipation – NA

NA = Not analyzed

a Because prometon is stable to abiotic hydrolysis and the aerobic and anaerobic aquatic metabolism studies have not 

been submitted, only % formation data is available from the aerobic and anaerobic soil metabolism and terrestrial 

field dissipation studies.

b Also degradate of propazine and prometryn

c Also degradate of propazine, prometryn, and atrazine

d Also degradate of propazine and atrazine

Prometon is expected to be mobile in both soil and aquatic environments. The average Koc of 

prometon in five agricultural soils is 117 L/kg (range = 82.6 to 172). The fate properties of 

prometon are presented in Table 4-2 for the parent only. No fate data (other than that presented 

in Table 4-1) are available for the degradates of prometon.

N

N

N

OCH3

H2N NH2

N

N

N

OH

H2N N

CH3

CH3

N

N

N

OH

H2N NH2
10

Table 4-2. Fate Profile for Prometon

Physico-chemical Characteristic Value Source

Vapor Pressure (mm Hg @ 20oC) 7.73 × 10-6 MRID 41609103

Water Solubility (mg/L @ 20oC) 720 MRID 41609103

Log KOW(@25oC) 2.69 MRID 41609103

Hydrolysis Stable in pH 5, 7, and 9 MRID 41114801

Photodegradation in Water Stable MRID 40225801

Photodegradation on Soil Stable MRID 41114802

Aerobic Soil Metabolism t1/2 = 462 days

t1/2 = 932 days

MRID 4145501

MRID 42313501

Anaerobic Soil Metabolism

Stable during 90 days, after 30 days aerobic

t1/2 = 462 days

Stable during 60 days, after 32 days aerobic

t1/2 = 557 days

MRID 40145501

MRID 42313501

Adsorption/desorption

Kd = 2.61 (1/n=0.893); Koc = 149.6 CA sandy loam

Kd = 2.90 (1/n=0.895); Koc = 172.0 Dubuque silt loam

Kd = 2.40 (1/n=0.868); Koc = 82.6 Kewaunee clay loam

Kd = 1.20 (1/n=0.911); Koc = 98.3 MS silt loam

Kd = 0.398 (1/n=0.738); Koc = 85.6 Plainfield sand MRID 40225803

Terrestrial Field Dissipation t1/2 =200 to 400 days – Fresno, CA

MRID 00162534

MRID 00162535

MRID 00162536

Prometon is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act4

. In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for prometon5

. The Impaired Waters and Total Maximum Daily Loads 

website can be consulted for more information6

. The Agency invites submission of water quality 

data for this pesticide. To the extent possible, data should conform to the quality standards in 

Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and 

Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management 

Process7

, in order to ensure they can be used quantitatively or qualitatively in pesticide risk 

assessments.

5 Ecological Effects Summary

5.1 Parent: Prometon

Studies characterizing the toxicity of prometon are provided in Table 5-1. No studies have been 

submitted since the 2008 RED.

 4 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

5

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES 6 http://www.epa.gov/owow/tmdl/ 7 http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf
11

Prometon is practically non-toxic to birds on an acute oral and sub-acute dietary basis;

practically non-toxic to terrestrial invertebrates on an acute contact basis; and slightly toxic to 

fish and aquatic invertebrates on an acute basis.

The study with green alga Selenastrum capricornutum (MRID 41725305) had been classified as 

Supplemental because the maximum application rate was not given in the study report. The 

classification of this study has been upgraded to Acceptable because the lack of a reported 

maximum application rate does not affect the scientific soundness of the study, and the study 

fulfills the guideline requirement for a freshwater algae toxicity study; the endpoints remain 

unchanged.

For the early life stage (ELS) study with fathead minnow (MRIDs 41810902, 42318202), a 

definitive NOEC was not previously determined for the most sensitive parameter of length (i.e., 

NOEC < 4.85 mg a.i./L; LOEC = 4.85 mg a.i./L). A re-analysis of the raw data for survival, 

hatching, length, and dry weight yielded a definitive NOEC of 19.7 mg a.i./L and a LOEC of 

37.0 mg a.i./L based on the most sensitive parameters of survival and hatching. The 

classification for the ELS study as Acceptable remains the same.

Registrant-submitted data are not available for the following:

• acute toxicity to a passerine,

• chronic toxicity to an estuarine/marine fish and invertebrate,

• toxicity to 3 species of aquatic non-vascular plants: cyanobacterium, freshwater diatom, 

and marine diatom, and

• toxicity to an aquatic vascular plant (i.e., Lemna spp.).

In previous ecological risk assessments (2008 RED, DP 335306; 2007 litigation assessment for 

the federally-listed Barton Springs salamander), ECOTOX open literature studies E009211 and 

E081431 were referenced for characterizing the toxicity of prometon to marine algae and aquatic 

vascular plants (i.e., Lemna spp.), respectively. Formal reviews of these studies conducted in 

accordance with current guidelines for evaluating ecological toxicity data in the open literature8

resulted in their classification as qualitative for use in the Registration Review ecological risk 

assessment due to the lack of sufficient experimental details (e.g., replication, test 

concentrations). In addition, a rainbow trout acute endpoint (i.e., LC50 = 12 mg/L) of ECOTOX 

open literature study E000546 was used in the RQ calculation for freshwater fish in the 2008

RED and litigation assessments because it was the most sensitive endpoint. This study will be 

reviewed to determine whether its results can be used quantitatively in the Registration Review 

ecological risk assessment.

It should be noted that the chronic, early life stage endpoint of 19.7 mg/L for freshwater fish 

(fathead minnow; MRIDs 41810902, 42318202) is approximately equal to the most sensitive 

acute endpoint of 19.6 mg/L for freshwater fish (rainbow trout; MRID 41609108). This 

discrepancy is probably due to the different species used in the tests (i.e., fathead minnow in the 

 8

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_evaluation_open_literature.htm
12

chronic test and rainbow trout in the acute test) and will be addressed in the Section 9 of this 

document. 

Table 5-1. Summary of the Endpoints from Toxicity Studies with Prometon

Study Type

TGAI/TEP (%) Species Toxicity Endpointsa

, Effects & Classification Source & 

Classification

Avian acute oral

TGAI

(98.5)

Bobwhite quail 

(Colinus 

virginianus)

LD50 > 2264 mg a.i./kg-bw

NOEL < 294 mg a.i./kg-bw

(no mortality; NOEL based sublethal effects 

including ruffled appearance, lethargy, s/a, reduced 

reaction to external stimuli, loss of coordination, 

lower limb weakness, depression, wing droop, and 

rapid respiration; also dose-response reduction in 

body weight at ≥ 489 mg a.i./kg-bw from days 0-3)

Practically non-toxic

MRID 41609104

Acceptable

Avian acute oral

TGAI

(NS)

Mallard duck 

(Anas 

platyrhynchus)

LD50 = 3157 mg/kg-bw

(symptoms preceding death included depression, 

wing droop, loss of coordination, prostrate posture, 

loss of righting reflex, convulsions, salivation, and 

shallow and rapid respiration; first death: 15 

minutes after dosing at 4640 mg/kg-bw)

Practically non-toxic

MRID 00079616

Acceptable

Avian acute oral Passerine No data

Avian sub-acute 

dietary

TGAI

(98.5)

Bobwhite quail 

(Colinus 

virginianus)

LC50 > 5620 mg/kg-diet

NOEC = 1000 mg/kg-diet

(no mortality; NOEC based on lethargy and ruffled 

appearance at ≥ 1780 mg/kg-diet; also reduction in 

feed consumption at 5620 mg/kg-diet)

Practically non-toxic

MRID 41609105

Acceptable

Avian sub-acute 

dietary

TGAI

(98.5)

Mallard duck 

(Anas 

platyrhynchus)

LC50 > 5620 mg/kg-diet

NOEC < 562 mg/kg-diet

(no mortality; NOEC based on dose-response 

reduction in weight gain; also reduction in feed 

consumption at ≥ 1780 mg/kg-diet)

Practically non-toxic

MRID 41606106

Acceptable

Avian reproduction

TGAI

(98.5)

Bobwhite quail 

(Colinus 

virginianus)

NOEC = 175 mg a.i./kg-diet

LOEC = 600 mg a.i./kg-diet

(based on a reduction in the number of viable 

embryos and live-3-week embryos)

MRID 42132101

Acceptable

Avian reproduction

TGAI

(98.5)

Mallard duck 

(Anas 

platyrhynchus)

NOEC = 50 mg a.i./kg-diet

LOEC = 175 mg a.i./kg-diet

(based on a reduction in adult body weight and 

eggshell thickness)

MRID 42132102

Acceptable

Terrestrial 

invertebrate acute 

contact

TGAI

(98.5)

Honeybee

(Apis mellifera)

48-hr LD50 (95% C.I.) = 37 (30.9-44.7) μg a.i./bee

Probit slope = 2.19

48-hr NOEC < 13 μg a.i./bee

(NOEC based on mortality and immobility)

Practically non-toxic

MRID 41609115

Acceptable

Terrestrial plant

Tier II

seedling emergence

TGAI

(98.5)

Most sensitive 

monocot: Oat

21-day EC25 = 0.0270 lb a.i./A

21-day NOEC = 0.0047 lb a.i./A

(based on dry weight) MRID 41725303

Acceptable Most sensitive 

dicot: Lettuce

21-day EC25 = 0.0100 lb a.i./A

21-day NOEC = 0.0094 lb a.i./A

(based on dry weight)
13

Study Type

TGAI/TEP (%) Species Toxicity Endpointsa

, Effects & Classification Source & 

Classification

Terrestrial plant

Tier II

vegetative vigor

TGAI

(98.5)

Most sensitive 

monocot: Oat

21-day EC25 = 0.016 lb a.i./A

21-day NOEC = 0.012 lb a.i./A

(based on dry weight) MRID 41725304

Acceptable Most sensitive 

dicot: Lettuce

21-day EC25 = 0.0080 lb a.i./A

21-day NOEC = 0.0047 lb a.i./A

(based on dry weight)

Freshwater fish 

acute

TGAI

Rainbow trout

(Oncorhynchus 

mykiss)

96-hr LC50 = 12 mg/L E000546

In review

Freshwater fish 

acute

TGAI

(98.5)

96-hr LC50 (95% C.I.) = 19.6 (17.1-22.4) mg a.i./L 

(m)

Probit slope = 8.6

96-hr NOEC = 6.36 mg a.i./L (m)

(NOEC based on sublethal effects including 

discoloration, lethargy, hyperventilation, erratic 

swimming, and loss of equilibrium) 

Slightly toxic

MRID 41609108

Acceptable

Freshwater fish 

acute

TGAI

(98.5)

Bluegill sunfish 

(Lepomis 

macrochirus)

96-hr LC50 = 41.5 mg a.i./L (m)

96-hr NOEC = 1.36 mg a.i./L (m)

(NOEC based on sublethal effects including 

discoloration, lethargy, loss of equilibrium; 

mortality only at highest test concentration of 58.8 

mg a.i./L) Slightly toxic

MRID 41609107

Acceptable

Freshwater fish 

chronic: 

Early life stage

TGAI

(98.5)

Fathead minnow 

(Pimephales 

promelas)

33-day NOEC = 19.7 mg a.i./L (mm)

33-day LOEC = 37.0 mg a.i./L (mm)

(based on a reduction in survival and hatching)

MRIDs 

41810902, 

42318202b

Acceptable

Estuarine/marine 

fish acute

TGAU

(98.5)

Sheepshead 

minnow

(Cyprinodon 

variegatus)

96-hr LC50 = 47.3 mg a.i./L (im)

96-hr NOEC = 3.99 mg a.i./L (im)

(NOEC based on sublethal effects including 

lethargy, loss of equilibrium, surfacing, 

discoloration, erratic swimming)

Slightly toxic

MRID 41725301

Acceptable

Estuarine/marine 

fish chronic No data

Freshwater 

invertebrate acute

TGAI

(98.5)

Water flea

(Daphnia 

magna)

48-hr EC50 (95% C.I.) = 25.7 (20.7-32.0) mg a.i./L 

(m)

Probit slope = 3.18

(NOEC not determined; immobility at all test 

concentrations)

Slightly toxic

MRID 41609109

Acceptable

Freshwater 

invertebrate chronic

TGAI

(97.7)

Water flea 

(Daphnia 

magna)

21-day NOEC = 3.45 mg a.i./L (mm)

21-day LOEC = 6.77 mg a.i./L (mm)

(based on a reduction in offspring production)

MRID 41810903

Acceptable

Estuarine/marine 

invertebrate acute

TGAI

(98.5)

Mysid shrimp

(Mysidopsis 

bahia)

96-hr LC50 (95% C.I.) = 17.7 (13.9-23.4) mg a.i./L 

(m)

Probit slope = 3.1

96-hr NOEC = 4.44 mg a.i./L (m)

(NOEC based on mortality; mortality at all test 

concentrations)

Slightly toxic

MRID 41609110

Acceptable
14

Study Type

TGAI/TEP (%) Species Toxicity Endpointsa

, Effects & Classification Source & 

Classification

Estuarine/marine 

invertebrate acute

TGAI

(97.7)

Eastern oyster

(Crassostrea 

virginica)

96-hr EC50 = 27.50 mg a.i./L (mm)

96-hr NOEC = 8.61 mg a.i./L (mm)

(NOEC based on statistically-significant shell 

deposition)

Slightly toxic

MRID 41810901

Acceptable

Estuarine/marine 

invertebrate chronic No data

Benthic invertebrate

whole sediment No data

Aquatic nonvascular plant

TGAI

(97)

Green alga

(Selenastrum 

capricornutum)

5-day EC50 (95% C.I.) = 0.098 (0.088-0.108) mg 

a.i./L (mm)

Probit slope = 3.41

5-day NOEC = 0.032 mg a.i./L (mm)

(based on cell count)

MRID 41725305

Acceptablec

Aquatic nonvascular plant Cyanobacterium No data

Aquatic nonvascular plantFreshwater 

diatom No data

Aquatic nonvascular plant Marine diatom No data

Aquatic vascular 

plant Duckweed No data

NS = not specified; C.I. = confidence interval a (im) = initial measured; (m) = measured; (mm) = mean-measured; (nom) = nominal b A 1992 re-review of the study after submission of raw length and weight data found that the study fulfilled the 

guideline requirement. However, a definitive NOEC was not determined for the most sensitive parameter of 

length (i.e., NOEC < 4.85 mg a.i./L; LOEC = 4.85 mg a.i./L). A re-analysis of the raw data for survival, hatching, 

length, and dry weight yielded a definitive NOEC of 19.7 mg a.i./L and a LOEC of 37.0 mg a.i./L based on the 

most sensitive parameters of survival and hatching. c upgraded from Supplemental (based on the maximum application rate not being provided in the study report) to 

Acceptable 

5.2 Prometon Degradates

Five major degradates of prometon have been identified based on environmental fate studies: 

GS-11526, GS-14626, GS-17794, GS12853, and GS-17791 (Table 4-1). There are no 

registrant-submitted toxicity data available for these degradates.

In the absence of toxicity data, predicted acute and chronic toxicity values for the major 

degradates of prometon were generated using EPA’s ECOSAR9 tool (v 1.1) which is based on 

quantitative structure activity relationships (QSAR) for effects on fish, daphnids, and green 

algae. Predicted toxicity values were also generated for parent prometon and compared to 

observed endpoints from registrant-submitted studies to assess confidence in the ability of 

ECOSAR to predict the toxicity of prometon’s degradates. The ECOSAR class of “triazines, 

aromatic” was used for comparative purposes even though output for other ECOSAR classes was 

 9 http://www.epa.gov/oppt/newchems/tools/21ecosar.htm
15

available for the degradates10. ECOSAR-predicted and observed toxicity values for prometon 

and its major degradates are provided in Table 5-2. If available, observed toxicity endpoints for 

degradates of other triazines that are closely related (i.e., have similar structures) to prometon 

degradates were also examined.

5.2.1 ECOSAR-Predicted vs. Observed Toxicity Endpoints for Parent 

Prometon

ECOSAR-predicted toxicity values for parent prometon were 1-2 orders of magnitude less than 

observed toxicity endpoints for fish, daphnids, and mysids implying that ECOSAR overpredicted toxicity to prometon for these taxa. In contrast, ECOSAR-predicted toxicity values for 

parent prometon were an ~3 times less than observed toxicity endpoint for green algae implying 

that ECOSAR marginally over-predicted toxicity to prometon for this taxon. 

5.2.2 GS-11526

Demethylation of the methoxy group of parent prometon produces degradate GS-11526. GS11526 is also a degradate of other triazine herbicides including propazine and prometryn. 

ECOSAR-predicted toxicity values indicate that GS-11526 is approximately as toxic as parent 

prometon, particularly with respect to green algae

Toxicity data for fish and aquatic invertebrates are available for the closely-related degradate of 

atrazine, hydroxyatrazine (HA, G-34048; CAS No. 2163-68-0). Given their structural similarity, 

the toxicity of hydroxyatrazine likely provides a reasonable approximation of the toxicity of GS11526 (Table 5-3). HA was not tested to high enough levels to yield definitive endpoints due to 

its limited solubility (see footnotes of Table 5-2). These observed non-definitive endpoints do 

not contradict the ECOSAR-predicted toxicity values, but do not provide any additional insight 

about the toxicity of GS-11526 because the highest concentrations tested are less than modeled 

concentrations.

Collectively, these approaches indicate that the toxicity of GS-11526 to aquatic taxa is 

comparable to that of parent prometon. Therefore, GS-11526 will be considered a stressor of 

concern in the Registration Review ecological risk assessment.

 10 ECOSAR classes (besides triazines): GS-11526 – phenols; GS-14626 – anilines (unhindered); GS-17794 –

anilines (unhindered), phenols, phenol amines; GS-12853 – anilines (amino-meta & unhindered); GS-17791 –

anilines (amino-meta & unhindered), phenols, phenol amines
16

Table 5-2. ECOSAR-predicted and Observed Toxicity Values for Prometon and Major Degradates

Taxon Exposure 

duration

Toxicity Value (mg/L)

Observed ECOSAR-Predicted (Using ECOSAR Class Triazines)

Prometon GS-11526a,b GS-14626 GS-17794c GS-12853 GS-17791d

FW fish 96-hr LC50

Chronic value

19.6-41.5

19.7

5.15

0.143

39.2e

1.0

74.7

1.9

559.6

13.8

1027

 24.8

7500

171.6

SW fish 96-hr LC50

Chronic value

47.3

No data

6.1

0.674

31.4f

2.1

51.6

2.9

260.5

9.0

411.9

11.9

2027.4

35.9

Daphnid 48-hr EC/LC50

Chronic Value

25.7

3.45

6.573

0.256

26.4g

1.1

39.6

1.7

156.3

7.1

225.5

10.5

869.0

43.3

Mysid 

shrimp

96-hr LC50

Chronic value

17.7

No data

0.874

0.085

4.6h

1.6

7.7

4.4

39.7

81.7

63.5

211.7

321.5

3868.3

Green 

algae

96-hr EC50

Chronic value 0.098 0.0380.031

0.106

0.062

0.138

0.072

0.376

0.144

0.471

0.160

1.255

0.311

FW = freshwater; SW = saltwater

a also degradate of prometryn and propazine

b closely related to hydroxyatrazine (HA), a degradate of atrazine

c also degradate of prometryn, propazine, and atrazine

d also degradate of propazine and atrazine

e observed toxicity values for related degradate HA: LC50 > 3.8 mg/L for bluegill sunfish (MRID 46500005); LC50 > 3.0 mg/L for rainbow trout (MRID 46500004) f observed toxicity values for related degradate HA: LC50 > 1.9 mg/L for sheepshead minnow (MRID 46500006) g observed toxicity values for related degradate HA: LC50 > 4.1 mg/L for water flea (MRID 46500001) h observed toxicity values for related degradate HA: LC50 > 2.0 mg/L for mysid shrimp (MRID 46500001)

Table 5-3. Comparison of Structures for Prometon Degradate GS-11526 and Atrazine Degradate G-34048 (Hydroxyatrazine)

Prometon Degradate GS-11526 Atrazine Degradate G-34048

Hydroxyatrazine

N

N

N

OCH3

N N

CH3

CH3

H3C

CH3

N

N

N

OH

N N

CH3

CH3

H3C

CH3

N

N

N

OCH3

N NH2

H3C

CH3

N

N

N

OH

H2N N

CH3

CH3

N

N

N

OCH3

H2N NH2

N

N

N

OH

H2N NH2

N

N

N

OH

N N

CH3

CH3

H3C

CH3

N

N

N

OH

N N

CH3

CH3

H3C

CH3
17

5.2.3 GS-14626 and GS-17794

Removal of an isopropyl group (i.e., R group) from parent prometon and GS-11526 produces 

degradates GS-14626 and GS-17794, respectively. GS-17794 is also a degradate of atrazine 

(i.e., deethylhydroxyatrazine; OIAT/ DHEA), propazine, and prometryn. ECOSAR-predicted 

toxicity values indicate that GS-14626 is approximately as toxic as parent prometon, particularly 

with respect to green algae, and that GS-17794 is less toxic than parent prometon to all taxa 

evaluated. Therefore, GS-17794 will not be considered a stressor of concern in the Registration 

Review ecological risk assessment. In contrast, S-14626 will be considered a stressor of concern 

in the Registration Review ecological risk assessment.

5.2.4 GS-12853 and GS-17791

Removal of an isopropyl group (i.e., R group) from degradates GS-14626 and GS-17794 

produces degradates GS-12853 and GS-17791, respectively. Thus these triazine degradates do 

not have any R groups. GS-17791 is also a degradate of atrazine (i.e., desethyl-desisopropyl-2-

hydroxy-atrazine; DIH) and propazine. ECOSAR-predicted toxicity values indicate that GS12583 and GS-17791 are less toxic than parent prometon to all taxa evaluated. Furthermore, the 

toxicity of triazines generally decreases with loss of substituted R groups (Marchini et al., 1988). 

Therefore, GS-12853 and GS-17794 will not be considered as stressors of concern in the 

Registration Review ecological risk assessment.

5.2.5 Summary of Degradate Toxicity

ECOSAR-predicted toxicity values indicate that GS-11526 and GS-14626 are approximately as 

toxic as parent prometon, particularly with respect to green algae. Therefore, these degradates 

will be considered stressors of concern in the Registration Review ecological risk assessment. In 

contrast, ECOSAR-predicted toxicity values indicate that GS-17794, GS-12853, and GS-17791

are less toxic than parent prometon to all taxa evaluated. Thus, these degradates will not be 

considered stressors of concern in the Registration Review ecological risk assessment.

5.3 Review of Incident Databases

Reviews on October 25, 2012 of the Ecological Incident Information System11 (EIIS, version 

2.1.1), which is maintained by the Agency’s Office of Pesticide Programs, and the Avian 

Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservatory, indicate a total of two reported ecological incidents (in EIIS) associated with the 

use of prometon. One incident (#I005895-355) involved fish mortality in a Kansas pond from an 

accidental misuse of prometon resulting in spillage. The certainty category regarding the 

likelihood that the use of prometon caused this incident is ‘probable’. The second incident 

(#I014409-078) involved damage to terrestrial plants including trees and lawn from misuse of 

 11 http://www.epa.gov/espp/consultation/ecorisk-overview.pdf
18

prometon on a Washington roadway by a paving contractor. The certainty category regarding 

the likelihood that the use of prometon caused this incident is ‘possible’.

In addition to the incidents recorded in EIIS and AIMS, additional incidents are reported to the 

Agency in aggregated form. Pesticide registrants report certain types of incidents to the Agency 

as aggregate counts of incidents occurring per product per quarter. Ecological incidents reported 

in aggregate reports include those categorized as ‘minor fish and wildlife’ (W-B), ‘minor plant’ 

(P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ incidents include reports of 

adverse effects to insects and other terrestrial invertebrates. For prometon, registrants have 

reported no minor fish and wildlife incidents, 12 minor plant incidents, and no other non-target 

incidents as of October 25, 2012.

The total number of actual incidents associated with the use of prometon may be higher than 

what is reported to the Agency. Incidents may go unreported since effects may not be 

immediately apparent and/or readily attributed to the use of a chemical.

6 Risk Hypothesis

The Registration Review ecological risk assessment will test the following risk hypothesis:

Based on the application methods, the assumed fate and transport, and the assumed 

sensitivity of non-target aquatic and terrestrial species, prometon has the potential to reduce 

survival, growth, and/or reproduction of non-target terrestrial and aquatic organisms as 

well as negatively affect the structure, productivity, and function of aquatic plant 

communities when used in accordance with the current labels. These non-target organisms 

include Federally-listed threatened and endangered species as well as non-listed species.

7 Exposure Pathways of Concern

For terrestrial vertebrates, the major route of exposure to prometon is considered to be via dietary 

ingestion of food items such as plants and/or animals that have prometon residues as a result of 

direct application, spray drift, and runoff. Exposure to terrestrial vertebrates through inhalation 

is considered unlikely given prometon’s low vapor pressure; however, a more quantitative 

analysis of risk through inhalation exposure via EFED’s Screening Tool for Inhalation Risk 

(STIR v. 1.0) is not possible because the lowest rat inhalation endpoint is non-definitive (LC50 > 

0.52 mg/L; MRID 42132104). EFED’s Screening Imbibition Program (SIP v. 1.0) indicates 

potential risk to birds but not to mammals from acute and chronic exposure through the 

consumption of drinking water with prometon residues (Appendix A).

For terrestrial invertebrates, the major routes of exposure to prometon are considered to be direct 

contact as a result of direct application and spray drift and dietary ingestion of plants, animals, 

and/or soil that have prometon residues as a result of direct application, spray drift, and runoff. 

Exposure to terrestrial invertebrates could also occur through guttation water.
19

For aquatic animal species, the major route of exposure to prometon is considered to be uptake 

via the respiratory surface (gills) or the integument from surface water/sediment that has 

prometon residues as a result of spray drift, runoff, and leaching to groundwater from soil.

For terrestrial (upland and semi-aquatic) non-target plants, the major routes of exposure to

prometon are considered to be direct contact as a result of direct application and spray drift and 

root uptake via soil contaminated via spray drift and runoff.

For aquatic plants, the major routes of exposure to prometon are considered to be uptake from

surface water/sediment containing prometon residues as a result of spray drift, runoff, and 

leaching to groundwater from soil.

8 Analysis Plan

To address the risk hypothesis, the potential for adverse effects on the environment will be 

estimated. Usage, environmental fate, and ecological effects of prometon will be characterized 

and integrated to assess the risks. Risk quotients (RQs) will be derived for prometon by dividing

estimated exposure concentrations (EECs) by the most sensitive endpoint from the relevant, 

available toxicity data for prometon. As outlined in the Overview Document (USEPA, 2004), 

the likelihood of effects to individual organisms from particular uses of a chemical is estimated 

using the probit dose-response slope and either the level of concern (LOC) or the actual 

calculated risk quotient value.

This analysis plan will be revisited and may be revised depending upon a full review of the data 

available in the open literature and the information submitted by the public in response to the 

opening of the Registration Review docket.

8.1 Stressors of Concern

Comparative toxicity modeling conducted in Section 5 indicates that GS-11526 and GS-14626 

are approximately as toxic as parent prometon to aquatic organisms. Therefore, in addition to 

parent prometon, these degradates will be considered stressors of concern in the Registration 

Review ecological risk assessment. In the absence of data on the toxicity of GS-11526 and GS14626, the conservative method of considering the stressors of concern in total, i.e., the total 

toxic residue (TTR) approach will be used.

8.2 Measures of Exposure 

To estimate risks to aquatic and terrestrial organisms from exposure to prometon, all exposure 

modeling and resulting risk conclusions will be made based on maximum application rates, 

application methods, and any mitigation measures specifically indicated on the label. Models 

that will be used to predict estimated environmental concentrations (EECs) of prometon are 

discussed on OPP’s model website12. These models include: PRZM (Pesticide Root Zone 

 12 http://www.epa.gov/pesticides/science/models_db.htm
20

Model) and EXAMS (EXposure Analysis Modeling System), PRZM-groundwater (PRZM-GW), 

T-REX, and TerrPlant.

8.3 Measures of Effect 

Ecological effects data are used as measures of direct and indirect effects to non-target 

organisms. Data are obtained from registrant-submitted studies or from literature studies 

identified by ECOTOX13. Information on the potential effects of prometon to non-target 

organisms is also collected from reviews of incidents associated with the use of prometon (see 

Section 4.3).

Where available, sub-lethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects may include behavioral changes (e.g., 

lethargy and changes in coloration). Quantitative assessments of risks, though, are limited to 

those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired 

survival, growth, and reproduction.

The assessment of risk for direct effects to non-target organisms makes the assumption that 

toxicity of prometon to birds is similar to terrestrial-phase amphibians and reptiles. The same 

assumption is made for fish and aquatic-phase amphibians. 

8.4 Integration of Exposure and Effects

Risk characterization is the integration of exposure and ecological effect characterizations to 

determine the potential ecological risk from the use of prometon and the likelihood of direct and 

indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and 

effects data are integrated to evaluate potential adverse ecological effects on non-target species. 

For the prometon risk assessment, the risk quotient (RQ) method will be used to compare 

estimated exposure and measured toxicity values. Acute and chronic EECs will be divided by 

acute and chronic toxicity values. The resulting RQs will then be compared to the Agency’s 

Levels of Concern (LOC) (USEPA, 2004). These criteria are used to indicate when prometon’s

use, as directed on the labels, has the potential to cause adverse direct or indirect effects to nontarget organisms. In addition, incident data from EIIS, aggregate incident reports, and AIMS 

will be considered as part of the risk characterization.

8.5 Drinking Water Assessment

A comprehensive drinking water assessment (based on all currently registered uses) may be 

conducted if requested by the Health Effects Division (HED) to support future human health 

dietary risk assessments of prometon as part of the Registration Review process. Any new 

drinking water assessment would incorporate model estimates as well as available monitoring 

data for prometon and any transformation products of toxicological concern (drinking water 

 13 http://cfpub.epa.gov/ecotox/
21

assessment residues of concern) that might be identified by HED for surface water and/or 

groundwater. The final determination of the residues of concern will be made through 

consultation with HED and through any proceedings of the ROCKS (Residues of Concern 

Knowledge Subcommittee).

8.6 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 prometon. This assessment will be conducted in accordance with the 

Overview Document (USEPA, 2004), provisions of the ESA, and the Services’ Endangered 

Species Consultation Handbook (USFWS/NMFS, 1998).

The assessment of effects associated with the registration of prometon is based on an action area. 

The action area is considered to be the area directly or indirectly affected by the federal action, as

indicated by the exceedance of Agency Levels of Concern (LOCs) used to evaluate direct or 

indirect effects. The Agency’s approach to defining the action area under the provisions of the 

Overview Document (USEPA, 2004) considers the results of the risk assessment process to 

establish boundaries for that action area with the understanding that exposures below the 

Agency’s defined LOCs constitute a no-effect threshold. For the purposes of this assessment, 

attention will be focused on the footprint of the action (i.e., the area where prometon application 

occurs), plus all areas where offsite transport (i.e., spray drift, runoff, etc.) may result in potential 

exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the 

action area for listed species include any direct and indirect effects and/or potential modification 

of its critical habitat, including reduction in survival, growth, and reproduction as well as the full 

suite of sub-lethal effects available in the effects literature. Therefore, the action area extends to 

a point where environmental exposures are below any measured lethal or sub-lethal effect 

threshold for any biological entity at the whole organism, organ, tissue, and cellular level of 

organization. In situations where it is not possible to determine the threshold for an observed 

effect, the action area will be assumed to encompass the entire United States.

8.7 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 the 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), prometon is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).
22

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 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. Prometon was

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 prometon. For additional 

information on the EDSP program, visit http://www.epa.gov/endo/.

9 Data Gaps

The following two sections identify environmental fate and effects data that are needed to 

complete an environmental fate and ecological risk assessment in support of the Registration 

Review of the registered uses of prometon.

9.1 Environmental Fate Data

Table 9-1 lists the status of the fate and transport data requirements for prometon. The fate 

database for prometon is complete (with the exception of aerobic aquatic metabolism studies and 

the analytical methods for soil, water, and sediment as noted in Table 9-1). 

Table 9-1. Registrant-Submitted Fate Data for Prometon and Remaining Data Gaps

Guideline Description MRID/

Source Classification Data Gap?

835.2120

161-1 Hydrolysis 0014615541114801

Unacceptable

Acceptable No

835.2240

161-2 Photodegradation in Water

40225801

92149014 Acceptable No

835.2410

161-3 Photodegradation in Soil

40225802

41114802

Unacceptable

Acceptable No

835.4100

162-1

Aerobic 

Soil Metabolism

40145501

42313501

Acceptable

Acceptable No
23

Guideline Description MRID/

Source Classification Data Gap?

835.4200

162-2

Anaerobic 

Soil Metabolism

40145501

42313501

Acceptable

Supplemental No

835.4300

162-4 Aerobic Aquatic Metabolism -- -- Yes

835.4400

162-3 Anaerobic Aquatic Metabolism -- -- Yes

835.1230

835.1240

163-1

Leaching-Adsorption/ 

Desorption 40225803 Acceptable No

835.6100

164-1

Terrestrial 

Field Dissipation

00162534

00162535

00162536

Acceptable No

850.6100 Analytical Method - Soil -- -- Yes

850.6100 Analytical Method - Water -- -- Yes

850.6100 Analytical Method- Sediment -- -- Yes

850.1730

165-4 Accumulation in fish

00125927

00125930 Acceptable No

166-2 Ground Water- small 

retrospective

45058801

45058802

Supplemental

Supplemental No

Submission of data to eliminate data gaps would reduce uncertainties in the exposure assessment. 

Data gaps have been assigned either a low or high potential to add value to the Registration 

Review risk assessment. While still considered data gaps according to 40 CFR Part 158, low 

potential studies are unlikely to change risk determinations because alternate methods and weight 

of evidence may possibly be used in the absence of data. High potential studies would enable the 

Agency to better characterize potential risks by eliminating exposure uncertainties that cannot be 

accounted for using alternate methods or weight of evidence.

Data from the following guideline studies are considered to have high potential to add value to 

the exposure assessment for prometon:

Guideline 835.4300 – Aerobic Aquatic Metabolism: Data for aerobic aquatic metabolism are 

required under 40 CFR Part 158. Given that the 2008 RED (DP 335306) identified a risk 

concern for aquatic organisms, fulfilling this data requirement has a high potential to add value 

to the Registration Review ecological risk assessment. In the absence of this data, the Agency 

will conservatively assume that prometon is stable to aerobic aquatic metabolism. Degradation 

measured in a new metabolism study would lower the exposure predicted by the agency’s 

aquatic modeling efforts.

Guideline 835.4400 – Anaerobic Aquatic Metabolism: Data for anaerobic aquatic metabolism

are required under 40 CFR Part 158. Given that the 2008 RED (DP 335306) identified a risk 

concern for aquatic organisms, fulfilling this data requirement has a high potential to add value 

to the Registration Review ecological risk assessment. In the absence of this data, the Agency 
24

will conservatively assume that prometon is stable to anaerobic aquatic metabolism. Any 

degradation measured in a new metabolism study would lower the exposure predicted by the 

agency’s aquatic modeling efforts.

Data from the following guideline studies are considered to have low potential to add value to 

the exposure assessment for prometon:

Guideline 850.6100– Analytical Methods – Soil, Water, and Sediment: Analytical methods 

for soil, water, and sediment are required under 40 CFR Part 158. However, prometon is already 

incorporated into U.S. Geological Survey multi-residue monitoring methods. Therefore in terms 

of performing an ecological risk assessment, little would be gained from these single residue 

analytical methods. 

Additional information that would have high potential to add value to the exposure modeling 

performed in the risk assessment would be detailed descriptions of the maximum spatial extent 

of prometon applications for all registered uses: agricultural/farm structures/buildings and 

equipment, airports/landing field, commercial/institutional/industrial premises/equipment 

(outdoor), commercial storage/warehouse premises, fencerows/hedgerows, 

industrial/construction areas (outdoor), nonagricultural outdoor buildings/structures, 

nonagricultural rights-of-way/fencerows/ hedgerows, nonagricultural uncultivated areas/soils, 

paved roads (private roads/sidewalks), recreational areas, and utility poles/rights-of-way. 

Prometon is used to kill all vegetation at the use site. Based solely on erosion concerns, it is 

unreasonable to expect a large area such as the 10 hectare EFED standard farm pond scenario 

watershed to be completely treated with prometon (i.e., denuded of vegetation for a year or 

more).

In order to better characterize the potential exposures estimated by modeling, a need exists for 

some kind of scientifically defensible estimate of the greatest percentage of a 10 ha watershed 

that could reasonably be expected to be treated with prometon for each of these uses. For 

example, these descriptions of the maximum spatial extent of prometon applications for the 

airports/landing field use might include the width of treated strip adjacent to a runway, the 

dimensions of a typical runway, and how many runways could be expected to traverse an 

approximately 10 ha watershed draining an airport. Such information would allow the Agency to 

scale the estimated environmental concentrations (EECs) to the proportion of the watershed 

treated for aquatic exposure assessment purposes.

9.2 Ecological Effects Data

Table 9-2 provides ecological effects studies by MRID that offer data for each guideline 

requirement as well as study classifications and whether or not further data are needed to support 

the Registration Review ecological risk assessment (i.e., whether there is a data gap).
25

In addition to parent prometon, degradates GS-11526 and GS-14626 will be considered stressors 

of concern in the Registration Review ecological risk assessment. In the absence of data on the 

toxicity of GS-11526 and GS-14626, the conservative TTR approach will be used for the 

stressors of concern. 

Table 9-2. Registrant-Submitted Ecological Effects Data for Prometon and Remaining 

Data Gaps

Guideline Description MRID/

Source Classification Data Gap?

850.1010 Acute toxicity 

freshwater invertebrates 41609109 Acceptable No

850.1025

850.1055

Acute toxicity

estuarine/marine mollusk 41810901 Acceptable No

850.1035

850.1045

Acute toxicity

estuarine/marine invertebrate 41609110 Acceptable No

850.1075

Acute toxicity

freshwater fish

(cold water species)

41609108 Acceptable

No; however, given that the 

freshwater fish acute and chronic 

endpoints are approximately equal, 

additional data – either an acute 

toxicity test with fathead minnow or 

a chronic test with rainbow trout –

are recommended.

Acute toxicity

freshwater fish 

(warm water species)

41609107 Acceptable

Acute toxicity

estuarine/marine fish 41725301 Acceptable No

850.1300

Aquatic invertebrate

life cycle

(freshwater)

41810903 Acceptable No

850.1350

Aquatic invertebrate

life cycle

(saltwater)

No data --

Yes, aquatic invertebrate life cycle 

toxicity data for an estuarine/marine 

invertebrate are required under 40 

CFR Part 158 if the product is 

expected to enter the environment in 

significant concentrations because of 

its expected use or mobility patterns.

850.1400

Fish early life-stage

(freshwater)

41810902 

42318202 Acceptable

No; however, given that the 

freshwater fish acute and chronic 

endpoints are approximately equal, 

additional data – either an acute 

toxicity test with fathead minnow or 

a chronic test with rainbow trout –

are recommended.

Fish early life-stage

(saltwater) No data --

Yes, early-life stage toxicity data for 

an estuarine/marine fish are required 

under 40 CFR Part 158 if the product 

is expected to enter the environment 

in significant concentrations because 

of its expected use or mobility 

patterns.
26

Guideline Description MRID/

Source Classification Data Gap?

850.2100

Avian oral toxicity 

(upland game or waterfowl 

species)

41609104

00079616

Acceptable

Acceptable No

Avian oral toxicity

(passerine species) No data --

Yes, avian acute oral toxicity data 

for a passerine species are required 

under the new 40 CFR Part 158.

850.2200

Avian dietary toxicity 

(upland game species) 41609105 Acceptable No

Avian dietary toxicity 

(waterfowl species) 41606106 Acceptable No

850.2300

Avian reproduction 

(upland game species) 42132101 Acceptable No

Avian reproduction 

(waterfowl species) 42132102 Acceptable No

850.3020 Honeybee acute contact 

toxicity 41609115 Acceptable No

850.4100 Seedling emergence 

(terrestrial plants) 41725303 Acceptable No

850.4150 Vegetative vigor 

(terrestrial plants) 41725304 Acceptable No

850.4400 Aquatic plant growth 

(aquatic vascular plant toxicity) -- --

Yes, data for an aquatic vascular 

plant – Lemna spp. – are required 

under 40 CFR Part 158.

850.4500

Aquatic plant growth

(aquatic non-vascular plant: 

algal toxicity)

41725305

(green alga) Acceptable No

No data for 

freshwater 

diatom

--

Yes, data for aquatic non-vascular 

plant species including a freshwater 

diatom are required under 40 CFR 

Part 158.

No data for 

marine 

diatom

--

Yes, data for aquatic non-vascular 

plant species including a marine 

diatom are required under 40 CFR 

Part 158.

850.4550

Aquatic plant growth

(aquatic non-vascular plant: 

cyanobacteria toxicity)

No data --

Yes, data for aquatic non-vascular 

plant species including a 

cyanobacterium are required under 

40 CFR Part 158.

FW = freshwater; SW = saltwater

Submission of data to eliminate data gaps would reduce uncertainties in the ecological effects 

assessment. Data gaps have been assigned either a low or high potential to add value to the 

Registration Review risk assessment. While still considered data gaps according to 40 CFR Part 

158, low potential studies are unlikely to change risk determinations because alternate methods 

and weight of evidence may possibly be used in the absence of data. High potential studies 

would enable the Agency to better characterize potential risks by eliminating uncertainties for 
27

both non-listed and listed species that cannot be accounted for using alternate methods or weight

of evidence.

Data from the following guideline studies are considered to have high potential to add value to 

the ecological risk assessment for prometon:

Guideline 850.1075 – Fish Acute Toxicity, fathead minnow or Guideline 850.1400 – Fish 

Early Life Stage Toxicity Test: The chronic, early life stage endpoint of 19.7 mg/L for 

freshwater fish (fathead minnow; MRIDs 41810902, 42318202) is approximately equal to the 

most sensitive acute endpoint of 19.6 mg/L for freshwater fish (rainbow trout; MRID 41609108). 

This discrepancy is probably due to the different species used in the tests (i.e., fathead minnow in 

the chronic test and rainbow trout in the acute test). Additional data – either an acute toxicity 

test with fathead minnow or a chronic test with rainbow trout – are recommended and considered 

to have a high potential to add value to the Registration Review risk assessment because the data 

will allow the Agency to evaluate risk to freshwater fish species. The data will also allow the 

Agency to generate an acute to chronic ratio (ACR) for evaluating risk to estuarine/marine fish 

species from chronic exposure to prometon. EFED Guidance recommends that acute and 

chronic toxicity values from the same species be used to calculate an ACR14. If an acute 

toxicity endpoint for fathead minnow is submitted, a fathead minnow ACR will be applied to the 

most sensitive freshwater fish acute toxicity endpoint for prometon to generate a chronic toxicity 

endpoint for freshwater fish. In the absence of this data, the most conservative freshwater fish 

ACR among the triazines may be applied to the most sensitive freshwater fish acute toxicity 

endpoint for prometon to generate a chronic toxicity endpoint for freshwater fish exposed to 

prometon.

Guideline 850.2100 – Avian Oral Toxicity, passerine species: Acute oral toxicity data for a 

passerine species are required under the new 40 CFR Part 158. No studies have been submitted 

for this data requirement. Given that the 2008 RED (DP 335306) identified a risk concern for 

birds from acute and chronic exposure, fulfilling this data requirement has a high potential to add 

value to the Registration Review ecological risk assessment as the generated data will allow the 

Agency to be protective of passerine species. In the absence of this data, passerine toxicity data 

for surrogate pesticides – starting with data for triazines and proceeding to data for less related 

chemicals – may be used to characterize the toxicity of prometon to passerine species.

Guideline 850.4400 – Aquatic Plant Toxicity Test Using Lemna spp.: Data for an aquatic 

vascular species (Lemna spp.) are required under 40 CFR Part 158. In previous risk assessments, 

an ECOTOX open literature study (E081431) was referenced for characterizing the toxicity of 

prometon to aquatic vascular plants (i.e., Lemna spp.). However, this study has been classified 

as qualitative for use in the Registration Review ecological risk assessment because of the lack 

of experimental details (e.g., replication, test concentrations). Given that the 2008 RED (DP 

335306) identified a risk concern for aquatic vascular plants, fulfilling this data requirement has 

a high potential to add value to the Registration Review risk assessment. In the absence of this 

data, the most conservative Lemna toxicity endpoints among the triazines may be used to 

characterize quantitatively the toxicity of prometon to aquatic vascular plant species.

 14 “Use of Acute-to-Chronic Ratios in Support of Ecological Risk Assessment of Pesticides.” EFED memo dated 

June 7, 2005.
28

Guideline 850.4500 – Algal Toxicity & Guideline 850.4550 – Cyanobacteria (Anabaena flosaqua) Toxicity: Data for aquatic non-vascular plant species are required under 40 CFR Part 158. 

No studies have been submitted for a freshwater diatom (e.g., Navicula pelliculosa), a marine 

diatom (e.g., Skeletonema costatum), or a cyanobacterium (e.g., Anabaena flos-aqua). In 

previous risk assessments, an ECOTOX open literature study (E009211) was referenced for 

characterizing the toxicity of prometon to marine algae. However, this study has been classified 

as qualitative for use in the Registration Review ecological risk assessment because of the lack 

of experimental details (e.g., replication, test concentrations). Given that the 2008 RED (DP 

335306) identified a risk concern for aquatic non-vascular plants, fulfilling this data requirement 

has a high potential to add value to the Registration Review risk assessment. 

A comparison of the toxicity endpoints for 4 marine alga species in a previously-cited open 

literature study (E009211) indicates that the tested species are 2.5 to 10 times less sensitive to 

prometon than the surrogate triazine atrazine. However, there is some uncertainty associated 

with this comparison because of insufficient experimental details. A comparison of the toxicity 

endpoints from registrant-submitted studies indicates that Selenastrum capricornutum is 2 times 

less sensitive to prometon (EC50 = 0.098 mg/L, NOEC = 0.032 mg/L; MRID 41725305) than 

atrazine (EC50 = 0.049 mg/L, NOEC = 0.016 mg/L; MRID 43074802) and confirms the toxicity 

relationship between prometon and atrazine for algae: algae tend to be less sensitive to prometon 

than atrazine. Since both of the registrant-submitted studies have been classified as acceptable, 

this comparison of toxicity endpoints has less uncertainty associated with it than that of the open 

literature ECOTOX study. Therefore, in the absence of data for a freshwater diatom, marine 

diatom, and cyanobacterium, a factor of 2 may be applied to the most conservative aquatic nonvascular plant endpoints (i.e., EC50 and NOEC) for atrazine to characterize quantitatively the 

toxicity of prometon to aquatic non-vascular plants. 

Data from the following guideline studies are considered to have low potential to add value to 

the ecological risk assessment for prometon:

Guideline 850.1350 – Mysid Chronic Toxicity Test: Aquatic invertebrate life cycle toxicity 

data for an estuarine/marine invertebrate are required under 40 CFR Part 158 if the product is 

expected to enter the environment in significant concentrations because of its expected use or 

mobility patterns. No studies have been submitted for this data requirement. Given that 

prometon is slightly toxic to aquatic animals on an acute basis, and there is no evidence to 

indicate that estuarine/marine animals are substantially more sensitive to prometon than 

freshwater animals, fulfilling this data requirement has a low potential to add value to the 

Registration Review risk assessment. In the absence of this data, toxicity to estuarine/marine 

invertebrates from chronic exposure to prometon may be characterized by applying an ACR

generated from toxicity data for Daphnia to the acute toxicity endpoint for mysid shrimp.

Guideline 850.1400 – Fish Early Life Stage Toxicity Test (Estuarine/Marine Species): Early 

life stage toxicity data for an estuarine/marine fish are required under 40 CFR Part 158 if the 

product is expected to enter the environment in significant concentrations because of its expected 

use or mobility patterns. No studies have been submitted for this data requirement. Given that 

prometon is slightly toxic to aquatic animals on an acute basis, and there is no evidence to 
29

indicate that estuarine/marine animals are substantially more sensitive to prometon than 

freshwater animals, fulfilling this data requirement has a low potential to add value to the 

Registration Review risk assessment. In the absence of this data, toxicity to estuarine/marine 

fish from chronic exposure to prometon may be characterized using toxicity data for freshwater 

fish exposed to prometon or toxicity data for estuarine/marine fish exposed to other triazines.

10 References

DP 335306. Ecological Risk Assessment in Support of the Re-registration Eligibility Decision 

for Prometon. August 31, 2007.

E000546. Bath, R., Ullmann, L., and Sachsse, K. 1973. Determination of pesticide toxicity to 

fish. Schriftenr. Ver. Wasser-Boden-Lufthyg. Berlin-Dahlem. 37: 241-256. (English 

translation).

E009211. Walsh, G.E. 1972. Effects of herbicides on photosynthesis and growth of marine 

unicellular algae. Hyacinth Control Journal 10: 45-48.

E081431. Drost, W., Backhous, T., Vassilakaki, Grimme, L.H. 2003. Mixture toxicity of striazines to Lemna minor under conditions of simultaneous and sequential exposure. 

Fresenius Environmental Bulletin. 12: 601-607. 

E013154. Marchini, S., Passerinei, L., Cesareo, D., and Tosato, M.L. (1988). Herbicidal 

triazines: Acute toxicity on Daphnia, Fish, and Plants and analysis of its relationships with 

structural factors. Ecotoxicology and Environmental Safety. 16: 148-157.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington D.C. January 23, 2004.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation and 

Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 

1998.

11 Bibliography of Cited MRIDs

Fate Studies

00022737 Corbin, F.T. (1965) The Influence of pH on the Detoxification of Herbicides in 

Soil. (Unpublished study received Aug 30, 1965 under 6F0466; prepared by 

North Carolina State Univ., Dept. of Crop Science, submitted by Velsicol 

Chemical Corp., Chicago, Ill.; CDL:090517-AE) 

00027134 Talbert, R.E.; Fletchall, O.H. (1965) The adsorption of some s-Triazines in soils. 
30

Weeds 13(?):46-52. (Also in unpublished submission received Jul 19, 1978 under 

201-403; submitted by Shell Chemical Co., Washington, D.C.; CDL:234472-J) 

00028395 Corbin, F.T.; Upchurch, R.P. (19??) Influence of pH on detoxification of 

herbicides in soil. Weeds 15(4):370-377. (Also In unpublished submission 

received Jan 5, 1968 under 8F0725; submitted by Velsicol Chemical Corp., 

Chicago, Ill.; CDL:091252-AL) 

00041353 Gerber, H.R.; Ziegler, P.; Dubach, P. (1970) Leaching as a tool in the evaluation 

of herbicides. Proceedings of the British Weed Conference 10:118-125. (Also in

unpublished submission received Mar 8, 1976 under 201-379; submitted by Shell 

Chemical Co., Washington, D.C.; CDL:223590-S) 

00055090 Weber, J.B.; Perry, P.W.; Upchurch, R.P. (1965) The influence of temperature 

and time on the adsorption of Paraquat, Diquat, 2,4-D and Prometone by clays, 

charcoal, and an anion-exchange resin. Soil Science Society of America 

Proceedings 29:678-688. (Also in unpublished submission received Apr 7, 1971 

under unknown admin. no.; submitted by Chevron Chemical Co., Richmond, 

Calif.; CDL:180000-F) 

00065619 Weber, J.B.; Weed, S.B. (1968) Adsorption and desorption of diquat, paraquat, 

and prometone by montomorillanitic and kaolinitic clay minerals. Soil Science 

Society of America Proceedings 32:485- 487. (Also in unpublished submission 

received Aug 22, 1977 un- der 239-1663; submitted by Chevron Chemical Co., 

Richmond, Calif.; CDL:231430-T) 

00065621 Weber, J.B.; Perry, P.W.; Upchurch, R.P. (1965) The influence of temperature 

and time on the adsorption of paraquat, diquat, 2,4-D and prometone by clays, 

charcoal, and an anion-exchange resin. Soil Science Society of America 

Proceedings 29(6):678- 688. (Also in unpublished submission received Aug 22, 

1977 un- der 239-1663; submitted by Chevron Chemical Co., Richmond, Calif.; 

CDL:231430-V) 

00075705 Holly, K.; Roberts, H.A. (1963) Persistence of phytotoxic residues of triazine 

herbicides in soil. Weed Research 3(? ):1-10. (Al- so in unpublished submission 

received Jul 19, 1978 under 201- 403; submitted by Shell Chemical Co., 

Washington, D.C.; CDL: 234476-AI) 

00114837 Corbin, F. (1965) The Influence of pH on the Detoxification of Herbicides in 

Soil. Doctoral thesis, North Carolina State Univ., Dept. of Crop Science. 

(Unpublished study received Mar 18, 1976 under 3E1385; submitted by U.S. 

Dept. of Interior, Bureau of Reclamation, Washington, DC; CDL:095210-N) 

00121317 Weber, J.; Weed, S. (1968) Adsorption and Desorption of diquat, paraquat, and 

prometone by montmorillonitic and kaolinitic clay minerals. Soil Science Society 

of America Proceedings 32:485- 487. (Also In unpublished submission received 

Dec 21, 1982 under 239-2247; submitted by Chevron Chemical Co., Richmond, 

CA; CDL:249102-T) 

00125922 Guth, J. (1976) Leaching Model Study with the Herbicide Prometon in Four 
31

Standard Soils: Project Report 31/76. (Unpublished study received Feb 13, 1978 

under 100-544; prepared by Ciba- Geigy, Ltd., Switz., submitted by Ciba-Geigy 

Corp., Greensboro, NC; CDL:232980-F) 

00125923 Halama, P.; Balu, K.; Hofberg, A. (1972) Photolysis of Prometone in Aqueous 

Solution under Natural and Artificial Sunlight Conditions: Report No. 72127. 

(Unpublished study received Feb 13, 1978 under 100-544; submitted by CibaGeigy Corp., Greensboro, NC; CDL:232980-G) 

00125924 Nixon, W. (1977) Letter sent to J. Ross dated May 27, 1977: Hydrolysis of 

Prometon. (Unpublished study received Feb 13, 1978 under 100-544; submitted 

by Ciba-Geigy Corp., Greensboro, NC; CDL:232980-H) 

00125926 Smith, K. (1977) [delta]14C-Prometon Soil Metabolism Study: Laboratory Nos. 

6E-2417, 6E-2419, 6E-2420. (Unpublished study received Feb 13, 1978 under 

100-544; prepared by Cannon Laboratories, Inc., submitted by Ciba-Geigy Corp., 

Greensboro, NC; CDL:232980-J) 

00125927 Smith, K. (1977) [delta]14C-Prometon Residue Study in Bluegill Sun- fish under 

Dynamic Flow Exposure Conditions: Laboratory No. 6E- 2421. (Unpublished 

study received Feb 13, 1978 under 100-544; prepared by Cannon Laboratories, 

Inc., submitted by Ciba-Geigy Corp., Greensboro, NC; CDL:232980-K) 

00125928 Smith, K. (1977) [delta]14C-Prometon Soil Parent Leaching Study: Laboratory 

No. 6E-2422. (Unpublished study received Feb 13, 1978 under 100-544; 

prepared by Cannon Laboratories, Inc., submitted by Ciba-Geigy Corp., 

Greensboro, NC; CDL:232980-L) 

00125929 Smith, K. (1977) [delta]14C-Prometon Soil Aged Leaching Study: Laboratory 

No. 6E-2423. (Unpublished study received Feb 13, 1978 under 100-544; 

prepared by Cannon Laboratories, Inc., sub- mitted by Ciba-Geigy Corp., 

Greensboro, NC; CDL:232980-M) 

00125930 Smith, K. (1977) Catfish Bioaccumulation during Exposure to delta 14CPrometon in a Soil/Water/Fish Ecosystem: Laboratory No. 7E- 5792. 

(Unpublished study received Feb 13, 1978 under 100-544; prepared by Cannon 

Laboratories, Inc., submitted by Ciba-Geigy Corp., Greensboro, NC; 

CDL:232980-N) 

00125931 Smith, K. (1977) Prometon Hydrolysis Study: Laboratory No. 7E- 6516. 

(Unpublished study received Feb 13, 1978 under 100-544; prepared by Cannon 

Laboratories, Inc., submitted by Ciba-Geigy Corp., Greensboro, NC; 

CDL:232980-O) 

00127711 Weber, J. (19??) Leachability of Atrazine, Buthidazole, Bromacil, Diuron, 

Diphacinone, and Prometon through a Lakeland Sand. (Unpublished study 

received Aug 21, 1978 under 876-EX-36; prepared by North Carolina State 

Univ., submitted by Velsicol Chemical Corp., Chicago, IL; CDL:234819-G) 

00127713 Weber, J. (19??) Adsorption and Characterization of Diphacinone and Prometon 
32

on Lakeland Sand, Alamance Silt Loam, Ca-montmorillonite, and Acidic Soil 

Organic Matter. (Unpublished study received Aug 21, 1978 under 876-EX-36; 

prepared by North Carolina State Univ., submitted by Velsicol Chemical Corp., 

Chicago, IL; CDL:234819-I) 

00134841 Weber, J.; Swain, L. (19??) Report to ...: Leachability of Atzrazine, Buthiazole, 

Bromacil, Diuron, Diphacinone and Prometon through a Lakeland Sand. 

(Unpublished study received Jul 12, 1978 under 876-EX-35; prepared by N.C. 

State Univ., submitted by Velsicol Chemical, Corp., Chicago, IL; CDL:234423-

I) 

00134843 Weber, J.; Swain, L. (19??) Report to ...: Adsorption and Characterization of 

Diphacinone and Prometon on Lakeland Sand, Alamance Silt Loam, Camontmorillonite and Acidic Soil Organic Mat- ter. (Unpublished study received 

Jul 12, 1978 under 876-EX-35; prepared by N.C. State Univ., submitted by 

Velsicol Chemical, Corp., Chicago, IL; CDL:234423-K) 

00146155 Hazleton Laboratories America, Inc. (1985) Hydrolysis of Prometon: Study No. 

6015-165. Unpublished study 19 p. 

00146156 Hazleton Laboratories America, Inc. (1985) Aqueous Solution Photolysis of 

Prometon: Interim Report: Study No. 6015-163. Unpublished study. 24 p. 

00146157 Hazleton Laboratories America Inc. (1985) Artificial Sunlight Photodegradation 

of Prometon on Soil: Interim Report: Study No. 6015-162. Unpublished study. 

33 p. 

00146158 Hazleton Laboratories America Inc. (1985) The Adsorption/Desorption of 

Radiolabeled Prometon on Representative Agricultural Soils: Study No. 6015-

164. Unpublished study. 48 p. 

00146159 Hazleton Laboratories America Inc. (1985) Mobility Determination of Prometon 

in Soils by Soil Thin Layer Chromatography: Study No. 6015-167. Unpublished 

study. 53 p. 

00146160 Hazleton Laboratories America Inc. (1985) Leaching Characteristics of Parent 

Prometon: Interim Report: Study No. 6015-201. Unpublished study. 27 p. 

00148344 Harris, C. (1966) Adsorption, movement, and phytotoxicity of monuron and sTriazine herbicides in soil. Weeds 14:6-10. 

00162534 Balcomb, R.; Honeycutt, R. (1986) Field Dissipation Studies on Prometon 

(Pramitol 25E)(Fresno, Ca): Rept. No. EIR-86013. Unpublished study prepared 

by Ciba-Geigy Corp. 161 p. 

00162535 Balcomb, R.; Honeycutt, R. (1986) Field Dissipation Studies on Prometon 

(Pramitol 25E) (Columbia, New York): Rept. No. EIR-86014. Unpublished study 

prepared by Ciba-Geigy Corp. 172 p. 

00162536 Balcomb, R.; Honeycutt, R. (1986) Field Dissipation Studies on Prometon 

(Pramitol 25E)(York, Nebraska): Rept. No. EIR-86018. Un- published study 
33

prepared by Ciba-Geigy Corp. 211 p. 

40145501 Obrist, J. (1987) Aerobic/Anaerobic and Sterile Soil Metabolism of Prometon: 

Laboratory Study No. 6015-309. Unpublished study prepared by Hazleton 

Laboratories America, Inc. 110 p. 

40225801 Puhl, R. (1987) Aqueous Solution Photolysis of Prometon: Laboratory Study No. 

6015-163. Unpublished study prepared by Hazleton Lab- oratories America, Inc. 

45 p. 

40225802 Puhl, R. (1987) Artificial Sunlight Photodecomposition of Prometon on Soil: 

Laboratory Study No. 6015-162. Unpublished study pre- pared by Hazleton 

Laboratories America, Inc. 49 p. 

40225803 Blair, J. (1986) Leaching Characteristics of Parent Prometon: Lab- oratory Study 

No. 6015-201. Unpublished study prepared by Hazleton Laboratories America, 

Inc. 53 p. 

41114801 Das, Y. (1989) Hydrolysis of [Triazine(U)-carbon 14] |Prometon in Aqueous 

Solutions Buffered at pH 5, 7 and 9: Proj. No. ISSI No. 89010. Unpublished 

study prepared by Innovative Scientific Services, Inc. 76 p. 

41114802 Das, Y. (1989) Photodegradation of Triazine(U)-carbon 14|Prometon on Soil 

Under Artificial Sunlight: Proj. No. ISSI No. 89021. Unpublished study prepared 

by Innovative Scientific Services, Inc. 124 p. 

42144603 Matt, F. (1988) The Adsorption and Desorption of [Carbon 14] Prometon on 

Representative Agricultural Soils: Final Report: Laboratory Project ID: HLA 

6117-139. Unpublished study prepared by Hazleton Laboratories America, Inc. 

69 p. 

42313501 Gohdes, M. (1992) Aerobic, Aerobic/Anaerobic, and Sterile Soil Metabolism of 

[carbon 14]-Prometon: Lab Project Number: HLA 6117-147. Unpublished study 

prepared by Hazleton Laboratories America, Inc. 240 p. 

92149013 Schabaker, D. (1990) Ciba-Geigy Corp. Phase 3 Summary of MRID 41114801. 

Hydrolysis of [Triazine (U) - Carbon-14] Prometon in Aqueous Solutions 

Buffered at pH 5,7,9: Project 89010; ISSI No. 89010. Prepared by 

INNOVATIVE SCIENTIFIC SERVICES, INC. 13 p. 

92149014 Schabacker, D. (1990) Ciba-Geigy Corp. Phase 3 Summary of MRID 40225801. 

Aqueous Solution Photolysis of Prometon: HLA Project No. 6015-163. Prepared 

by HAZLETON LABS. AMERICA, INC. 14 p. 

92149016 Schabacker, D. (1990) Ciba-Geigy Corp. Phase 3 Summary of MRID 41114802. 

Photodegradation of [Triazine(U)-carbon-14] Prometon on Soil under Artificial 

Sunlight: ISSI No. 89021. Prepared by Innovative Scientific Services, Inc. 19 p. 

92149017 Schabacker, D. (1990) Ciba-Geigy Corp. Phase 3 Summary of MRID 40225803. 

Prometon - Leaching Study: Project 6015-201. Prepared by HAZLETON LABS. 

AMERICA, INC. 18 p. 
34

92149018 Schabacker, D. (1990) Ciba-Geigy Corp. Phase 3 Summary of MRID 92149021. 

The Adsorption and Desorption of [Carbon-14] Prometon on Representative 

Agricultural Soils: HLA 6117-139. Prepared by Hazleton Laboratories America, 

Inc. 12 p. 

Ecological Effects Studies

00079616 Fink, R. (1976) Final Report: Acute Oral LD50--Mallard Duck: Project No. 108-

122. (Unpublished study received Sep 15, 1977 under 100-544; prepared by 

Wildlife International, Ltd., submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:231814-H) 

41609104 Campbell, S. (1990) Prometon: An Acute Toxicity Study with the Northern 

Bobwhite: Lab Project Number: 108-326. Unpublished study prepared by 

Wildlife International Ltd. 22 p. 

41609105 Long, R. (1990) Prometon: A Dietary LC50 Study with the Northern Bobwhite: 

Lab Project Number: 108-324. Unpublished study pre- pared by Wildlife 

International Ltd. 52 p. 

41609107 Murphy, D. (1990) Prometon: A 96-hour Static Acute Toxicity Test with the 

Bluegill (Lepomis macrochirus): Lab Project Number: 108A-103A. Unpublished 

study prepared by Wildlife International Ltd. 49 p. 

41609108 Murphy, D. (1990) Prometon: A 96-hour Static Acute Toxicity Test with the 

Rainbow Trout (Oncorhynchus mykiss): Lab Project Number: 108A-102B. 

Unpublished study prepared by Wildlife International Ltd. 49 p. 

41609109 Bellantoni, D. (1990) Prometon: A 48-hour Static Acute Toxicity Test with the 

Cladoceran (Daphnia magna): Lab Project Number: 108A-101. Unpublished

study prepared by Wildlife International Ltd. 50 p. 

41609110 Murphy, D. (1990) Prometon: A 96-hour Static Acute Toxicity Test with the 

Saltwater Mysid (Mysidopsis bahia): Lab Project Number: 108A-105A. 

Unpublished study prepared by Wildlife International Ltd. 50 p. 

41609111 Murphy, D. (1990) Prometon: A 96-hour Static Acute Toxicity Test with the 

Sheepshead Minnow (Cyprinodon variegatus): Lab Project Number: 108A-104. 

Unpublished study prepared by Wildlife Inter- national Ltd. 51 p. 

41609115 Hoxter, K. (1990) Prometon: An Acute Contact Toxicity Study with the Honey 

Bee: Lab Project Number: 108-323. Unpublished study prepared by Wildlife 

International Ltd. 16 p. 

41725301 Murphy, D. (1990) A 96-Hour Static Acute Toxicity Test with the Sheepshead 

Minnow (Cyprinodon variegatus): Amended Report to: Lab Project Number: 

108A-104. Unpublished study prepared by Wildlife International Ltd. 52 p. 

41725303 Chetram, R. (1990) Tier 2 Seedling Emergence Nontarget Phytotoxicity Study 

Using Prometon Technical: Lab Project Number: LR90-05. Unpublished study 
35

prepared by Pan-Agricultural Laboratories. 274 p. 

41725304 Chetram, R. (1990) Tier 2 Vegetative Vigor Nontarget Phytotoxicity Study Using 

Prometon Technical: Lab Project Number: LR90-03. Unpublished study prepared 

by Pan-Agricultural Laboratories, Inc. 224 p. 

41725305 Hughes, J. (1990) The Toxicity of Prometon to Selenastrum capricornutum: Lab 

Project Number: B267-47-1. Unpublished study pre- pared by Malcolm Pirnie, 

Inc. 33 p. 

41810902 Peters, G. (1991) An Early Life-Stage Toxicity Test with the Fathead Minnow 

(Pimephales promelas): Lab Project No: 108A-115A. Unpublished study 

prepared by Wildlife International Ltd. 47 p. 

41810901 Ward, T. (1991) Acute Flow Through Mollusc Shell Deposition Test with 

Prometon: Lab Project Number: 9113-CG. Unpublished study prepared by 

Resource Analysts, Inc., Envirosystems Div. 36 p. 

41810903 Peters, G. (1991) A Flow-through Life-cycle Toxicity Test with the Cladoceran 

(Daphnia magna): Lab Project Number: 108A-114E. Unpublished study 

prepared by Wildlife International Ltd. 49 p. 

42132101 Beavers, J. (1991) Prometon: A One-Generation Reproduction Study with the 

Bobwhite (Colinus virginianus): Lab Project Number: 108-318. Unpublished 

study prepared by Wildlife International Ltd. 141 p. 

42132102 Beavers, J. (1991) Prometon: A One-Generation Reproduction Study with the 

Mallard (Anas platyrhynchos): Lab Project Number: 108-319. Unpublished study 

prepared by Wildlife International Ltd. 142 p. 

42318202 Graves, W.; Peters, G. (1992) A Supplement to an Early Life-Stage Toxicity Test 

with the Fathead Minnow (Pimephales Promelas). Unpublished study prepared 

by Ciba-Geigy Corp. 19 p. 
36

Appendix A: SIP (v 1.0) Inputs and Results

The purpose of this model is to provide an upper bound estimate of exposure of birds and mammals to 

pesticides through drinking water alone. This model is intended for use in problem formulation to 

determine whether or not drinking water exposure alone is a potential pathway of concern. This does 

not aggregate drinking water exposure with other exposure routes (i.e., diet, inhalation, dermal).

Assumptions:

SIP employs the following conservative assumptions to derive upper bound exposure estimates:

1) The chemical concentration in drinking water is at the solubility limit in water (at 25oC).

2) The assessed animals obtain 100% of their daily water needs through drinking water.

3) The daily water need is equivalent to the daily water flux rate as calculated by Nagy and Peterson 

(1988).

4) The body weight of the assessed bird is equivalent to the smallest generic bird modeled in T-REX 

(i.e., 20 g). This assumption results in the highest ratio of exposure to toxicity for the 3 assessed avian 

body weights of T-REX (i.e., 20, 100, 1000 g).

5) The body weight of the assessed mammal is equivalent to the largest generic mammal modeled in 

T-REX (i.e., 1000 g). This results in the highest ratio of exposure to toxicity for the 3 assessed 

mammalian body weights of T-REX (i.e., 15, 35, 1000 g). 

Table 1. Inputs

Parameter Value

Chemical name prometon

Solubility (in water at 25oC; mg/L) 620

Mammalian LD50 (mg/kg-bw) 1518

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 20

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

NOTE: This endpoint is 

non-definitive. However, 

use of the definitive

endpoint of 3157 mg/kg-bw 

for mallard duck yields the 

same results.

Avian LD50 (mg/kg-bw) 2264

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 50

Bobwhite quail NOAEC (mg/kg-diet) 175

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
37

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 106.6400 106.6400

Adjusted toxicity value (mg/kg-bw) 1167.5857 15.3832

Ratio of exposure to toxicity 0.0913 6.9322

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Exposure through 

drinking water alone is a 

potential concern for 

mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 502.2000 502.2000

Adjusted toxicity value (mg/kg-bw) 1631.0524 2.4806

Ratio of exposure to acute toxicity 0.3079 202.4487

Conclusion*

Exposure through 

drinking water alone is a 

potential concern for 

birds

Exposure through 

drinking water alone is 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.