OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

 

PC Code: 122019 

DP Barcode: 423550 

MEMORANDUM March 3, 2015 

SUBJECT: Preliminary Environmental Fate and Ecological Risk Assessment for the 

Registration Review of Propoxycarbazone-sodium 

FROM: Elyssa Arnold, Biologist 

 James Lin, Environmental Engineer 

 Environmental Risk Branch 2 

Environmental Fate and Effects Division (7507P) 

REVIEWED Donna Judkins, Biologist

BY: Greg Orrick, Environmental Scientist 

 Environmental Risk Branch 2 

Environmental Fate and Effects Division (7507P) 

THROUGH: Brian Anderson, Branch Chief 

Environmental Risk Branch 2 

 Environmental Fate and Effects Division (7507P) 

 

TO: Lata Venkateshwara, Chemical Review Manager 

 Avivah Jakob, Team Leader 

 Neil Anderson, Acting Branch Chief 

Risk Management and Implementation Branch 3 

Pesticide Re-evaluation Division (7508P) 

Attached please find the Environmental Fate and Effects Division’s Preliminary Environmental 

Fate and Ecological Risk Assessment for the Registration Review of propoxycarbazone-sodium. 

The assessment characterizes potential ecological risk from the currently registered uses of 

propoxycarbazone-sodium on wheat, triticale, rangeland, pastures, and Conservation Reserve 

Program land. The assessment finds that terrestrial plants are the only taxa for which risks from 

these uses exceed levels of concern. Direct effects on terrestrial plants could result in indirect 

effects to all other taxa.

Digitally signed by JAMES LIN 

DN: c=US, o=U.S. Government, ou=USEPA, 

ou=Staff, cn=JAMES LIN, dnQualifier=0000014809 

Date: 2015.03.03 17:40:18 -05'00'

Anderson, Brian 

2015.03.04 

16:45:03 -05'00'

2015.03.04 

16:48:06 -05'00'

2015.03.04 17:19:38 -05'00'
 

Preliminary Environmental Fate and Ecological Risk Assessment 

for the Registration Review of Propoxycarbazone-sodium 

Propoxycarbazone-sodium

CAS 181274-15-7 PC Code 112019 

3 March 2015 

Prepared by

Elyssa Arnold, Biologist 

Jim Lin, Environmental Engineer 

U.S. Environmental Protection Agency 

Office of Pesticide Programs 

Environmental Fate and Effects Division (EFED) 

Environmental Risk Branch II 

1200 Pennsylvania Ave., NW 

Mail Code 7507P 

Washington, DC 20460

Reviewed by 

Donna Judkins, Biologist 

Greg Orrick, Environmental Scientist 

Brian Anderson, Branch Chief 

 
-Page 3 of 66- 

Table of Contents 

1. Executive Summary ........................................................................................................................................... 4

2. Problem Formulation ....................................................................................................................................... 6

2.1. Nature of Regulatory Action ................................................................................................................... 6

2.2. Stressor Source and Distribution ............................................................................................................ 6

2.2.1. Nature of the Chemical Stressor ...................................................................................................... 6

2.2.2. Overview of Pesticide Usage ............................................................................................................. 7

2.3. Receptors .................................................................................................................................................. 7

2.3.1. Aquatic and Terrestrial Effects ........................................................................................................ 7

2.3.2. Ecosystems Potentially at Risk ......................................................................................................... 8

2.4. Assessment Endpoints .............................................................................................................................. 8

2.5. Conceptual Model ..................................................................................................................................... 9

2.5.1. Risk Hypotheses .................................................................................................................................. 9

2.5.2. Conceptual Diagram ......................................................................................................................... 10

2.6. Analysis Plan ........................................................................................................................................... 11

2.6.1. Measures of Exposure .................................................................................................................... 11

2.6.2. Measures of Effect .......................................................................................................................... 13

2.6.3. Integration of Exposure and Effects ............................................................................................. 13

3. Analysis ............................................................................................................................................................ 15

3.1 Use Characterization ................................................................................................................................... 15

3.2. Exposure Characterization .................................................................................................................... 16

3.2.1. Environmental Fate and Transport Characterization ................................................................. 16

3.2.2. Measures of Aquatic Exposure ....................................................................................................... 23

3.2.3. Measures of Terrestrial Exposure .................................................................................................. 25

3.3. Ecological Effects Characterization ...................................................................................................... 28

3.3.1. Aquatic Effects Characterization ................................................................................................... 28

3.3.2. Terrestrial Effects Characterization .............................................................................................. 31

3.3.3. Review of Incident Data .................................................................................................................. 34

4. Risk Characterization ...................................................................................................................................... 34

4.1. Risk Estimation ....................................................................................................................................... 34

4.1.1. Aquatic Organisms .......................................................................................................................... 35

4.1.2. Terrestrial Organisms ..................................................................................................................... 35

4.2. Risk Description ...................................................................................................................................... 37

4.2.1. Risks to Aquatic Organisms ........................................................................................................... 37

4.2.2. Terrestrial Organisms ..................................................................................................................... 38

5. Listed Species of Concern ................................................................................................................................ 42

5.1. Evaluating Risks to Listed Species ........................................................................................................ 42

5.2. Taxonomic Groups Potentially at Risk ................................................................................................. 43

6. Endocrine Disruptor Screening Program ...................................................................................................... 43

7. Conclusions ....................................................................................................................................................... 44

8. Data Gaps ......................................................................................................................................................... 45

9. References ......................................................................................................................................................... 51

9.1. Submitted Product Chemistry and Environmental Fate Studies ....................................................... 53

9.2. Submitted Ecotoxicity Studies ............................................................................................................... 56

Appendix A. SWCC Modeling Summary for Propoxycarbazone-sodium .......................................................... 59

Appendix B. Example T-REX Input and Output for Propoxycarbazone-sodium .............................................. 61

Appendix C. Example TERRPLANT (v. 1.2.2) Input and Output for Propoxycarbazone-sodium .................. 64

Appendix D. STIR Results for Propoxycarbazone-sodium .................................................................................. 65

Appendix E. SIP Results for Propoxycarbazone-sodium ...................................................................................... 66

 
-Page 4 of 66- 

1. Executive Summary 

The preliminary risk assessment (PRA) examines the potential ecological risks associated with 

labeled uses of the herbicide propoxycarbazone-sodium based on the best available scientific and 

commercial information on the use, environmental fate and transport, and effects of 

propoxycarbazone-sodium on non-target organisms. Propoxycarbazone-sodium is a sulfonylamino-carbonyl-triazolinone herbicide registered for use on wheat, triticale, rangeland, pastures, 

and Conservation Reserve Program land. It is used for post-emergence control of grasses and 

broadleaf plants at a maximum single application rate of 0.0525 lb a.i./A. 

Propoxycarbazone-sodium is very mobile in soil, with high water solubility (42,000 mg/L) and 

low soil partitioning coefficients (Kd = 0.22 to 1.07). The chemical has a low vapor pressure (7.1 

x 10-11 mmHg) and is not likely to bioaccumulate (Kow = 0.028). Propoxycarbazone-sodium 

degrades slowly with fairly long half-lives by all measured routes including hydrolysis (433-495 

days at pH 7), photolysis (37-94 days), aerobic soil metabolism (8.7-224 days), aerobic aquatic 

metabolism (107-210 days), and anaerobic aquatic metabolism (1155 days). Terrestrial field 

dissipation half-lives ranged from 12 to 56 days. While propoxycarbazone-sodium has a number 

of major degradates, none were identified to be of ecological concern. 

Propoxycarbazone-sodium is practically non-toxic on an acute exposure basis to all animal taxa, 

including birds, mammals, terrestrial invertebrates, fish, and aquatic invertebrates. Chronic 

toxicity effects were observed at high doses in studies of birds and mammals. Propoxycarbazonesodium is very highly toxic to the vascular aquatic plant duckweed. The next most sensitive 

aquatic plant species tested was green algae, which was two orders of magnitude less sensitive 

than duckweed. Consistent with the herbicidal mode of action, terrestrial plants are sensitive to 

propoxycarbazone-sodium exposure. Similar levels of toxicity were observed to monocots and 

dicots in both the seedling emergence and vegetative vigor studies. 

Although data from the acute contact and oral toxicity tests with young adult honey bees (Apis 

mellifera) indicate propoxycarbazone-sodium is practically non-toxic to bees on an acute 

exposure basis, there is uncertainty regarding the potential acute and chronic effects of the 

compound on honey bee larval development and survival as well as potential for chronic effects 

of adult bees. Since propoxycarbazone-sodium is a systemic herbicide, residues may be 

transported by the plant into pollen and/or nectar and represent a route of exposure for bees 

through ingestion. Studies to address these uncertainties are specified by the Guidance for 

Assessing Pesticide Risks to Bees (USEPA et al., 2014). See Section 8 for additional details. 

The data gaps include: 

1. Non-guideline Study (Tier 1) – Honey bee larvae acute oral toxicity 

2. Non-guideline Study (Tier 1) – Honey bee adult chronic oral toxicity 

3. Non-guideline Study (Tier 1) – Honey bee larvae chronic oral toxicity 

4. Non-guideline Study (Tier 2) – Semi-field testing for pollinators (tunnel or colony 

feeding studies) 

5. Non-guideline Study (Tier 2) – Field trial of residues in pollen and nectar 

6. OCSPP 850.3040 (Tier 2 or 3) – Field testing for pollinators 
-Page 5 of 66- 

Terrestrial plants are the only taxa for which risks exceed levels of concern for currently 

registered propoxycarbazone-sodium uses. Direct effects on terrestrial plants could result in 

indirect effects to all other taxa due to habitat modifications (e.g., food sources, shelter, and areas 

to reproduce). Spray drift buffers from treated fields would need to be >1,000 ft for listed 

terrestrial plants and up to 900 ft for non-listed terrestrial plants to decrease risks below the 

levels of concern. Additionally, there is a potential for damage to terrestrial plants if surface or 

groundwater contaminated with propoxycarbazone-sodium is used for irrigation. 

Figure 1.1 and Table 1.1 give a broad overview of the potential risk concerns and supporting 

evidence for registered uses of propoxycarbazone-sodium. 

Figure 1.1. Graphic Summary of Potential Risks of Current Uses of Propoxycarbazone-sodium 

Table 1.1. Evidence of Risk to Taxonomic Groups from Current Uses of Propoxycarbazone-sodium 

Predominant Evidence of Negligible Risk Predominant Evidence of Risk 

Mammals, birds, fish, aquatic invertebrates, aquatic 

plants: All RQs <LOC for listed and non-listed species. 

No incidents reported. 

Terrestrial Plants: RQs > LOC (up to 850) for listed and 

non-listed monocots and dicots for all uses. Multiple 

incidents reported. 

Limited Evidence of Negligible Risk Limited Evidence of Risk 

Terrestrial Invertebrates: No mortality observed in acute 

contact and acute oral studies on adult honey bees. No 

chronic toxicity data or larval toxicity data available. 

N/A 

Certainty

Risk

Propoxycarbazone-sodium

Fish Terr. Plants

Mammals Birds

Aq. Inverts

Aq. Plants

Terr. Inverts
-Page 6 of 66- 

2. Problem Formulation 

The purpose of problem formulation is to provide the foundation for the environmental fate and 

ecological risk assessment being conducted for the representative labeled uses of 

propoxycarbazone-sodium. The problem formulation sets the objectives for the risk assessment 

and provides a plan for analyzing the data and characterizing the risk (USEPA, 1998). Distinct 

from other Registration Review cases, no preliminary problem formulation was developed for 

propoxycarbazone-sodium due to a relatively complete set of fate and transport as well as 

ecotoxicity data at the time of the initial docket opening. 

Ecological risk from propoxycarbazone-sodium use on wheat was previously assessed at the time 

of the initial pesticide registration in 2004 (USEPA, 2004b). Propoxycarbazone-sodium use on 

pasture and rangeland was subsequently assessed in 2008 (USEPA, 2008). Updated assessment 

methods and models are used in this document. Conclusions regarding risks to non-target species 

are consistent with those in previous assessments with the exception of listed vascular aquatic 

plants. As a result of slight differences in the calculated toxicity endpoint1, risks exceeding levels 

of concern were identified in the 2008 assessment, but are not identified in this assessment. Risks 

exceeding the levels of concern for terrestrial plants are identified in all previous and current 

assessments. 

2.1. Nature of Regulatory Action 

The risk assessment is conducted as part of the Agency’s Registration Review process for 

pesticide active ingredients. The Registration Review process was established under the Food 

Quality Protection Act (FQPA 1996), which amended the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA). 

2.2. Stressor Source and Distribution 

2.2.1. Nature of the Chemical Stressor 

Propoxycarbazone-sodium is a sulfonyl-amino-carbonyl-triazolinone herbicide used for the 

selective post-emergence control of grasses and broadleaf plants. Propoxycarbazone is absorbed 

through the foliage and root systems of plants, and acts as an inhibitor of the enzyme 

acetolactase synthase (ALS). The chemical profile of propoxycarbazone-sodium is provided in 

Table 2.1. Chemical names and structures of propoxycarbazone-sodium degradates are listed in 

Table 3.3. This screening-level ecological risk assessment focuses on propoxycarbazone-sodium 

parent only because none of the identified transformation products were found to be of 

ecological concern. 

 

1

 The 2008 assessment calculated RQs for listed vascular aquatic plant species using the EC05 of 0.002 μg a.i./L. 

Because there is a definitive NOAEC value of 0.0031 μg a.i./L from the same study (MRID 45012815), this 

assessment uses the NOAEC rather than the EC05. The exposure estimate is 0.0023 μg/L in both assessments. 
-Page 7 of 66- 

Table 2.1. Chemical Profile of Propoxycarbazone-sodium

Common name Propoxycarbazone-sodium 

IUPAC name sodium {[2-(methoxycarbonyl)phenyl]sulfonyl}[(4,5-dihydro-4-

methyl-5-oxo-3-propoxy-1H-1,2,4-triazol-1-yl)carbonyl]azanide 

CAS name Methyl 2-((((4,5-dihydro-4-methyl-5-oxo-3-propoxy-1H-1,2,4-triazol1-yl)carbonyl)amino)sulfonyl)benzoate sodium salt 

Structure 

Pesticide type Herbicide 

CAS number 181274-15-7 

Empirical formula C15H17N4NaO7S 

Molecular mass 420.37 g/mol 

2.2.2. Overview of Pesticide Usage 

Propoxycarbazone-sodium, an herbicide that controls certain post-emergent grasses and 

broadleaf weeds, was initially registered in June 2004. There are currently six active Section 3 

registrations for propoxycarbazone-sodium, including one technical, OlympusTM MKH 6561 

Technical (EPA Reg No. 264-808). The five end-use products include Olympus® 70% Water 

Dispersible Granular Herbicide (EPA Reg No. 264-809), OlympusTM Flex Herbicide (EPA Reg 

No. 264-833), OlympusTM Rangeland Herbicide (EPA Reg No. 264-1074), RimfireTM Herbicide 

(EPA Reg No. 264-847), and RimfireTM Max Herbicide (EPA Reg No. 264-1099). 

Propoxycarbazone-sodium is currently registered for use on wheat, triticale, rangeland, pastures, 

and Conservation Reserve Program land. Based on available proprietary usage data, the 

predominant use of propoxycarbazone-sodium is on winter wheat (USEPA, 2014a). 

Propoxycarbazone-sodium products are water dispersible granules and are applied as a pre-plant, 

pre-emergence, and post-emergence application via ground (broadcast or hand-held spot 

treatment) or aerial methods. Application rates are similar for all use patterns. The highest annual 

and single maximum application rates are 0.0525 lb a.i./A. Specific use rates are discussed in 

Section 3.1.

Three of the propoxycarbazone-sodium products currently registered for use on wheat and 

triticale (OlympusTM Flex, RimfireTM, and RimfireTM Max) contain mesosulfuron-methyl as a 

second active ingredient. This evaluation is limited to exposure to propoxycarbazone-sodium, 

and does not include estimated concentrations of other active ingredient residues. 

2.3. Receptors 

2.3.1. Aquatic and Terrestrial Effects 

The receptor is the biological entity that is exposed to the stressor (USEPA, 1998). Consistent 

with the process described in the Overview Document (USEPA, 2004a), this risk assessment 

uses a surrogate species approach in its evaluation of propoxycarbazone-sodium. Toxicity data 
-Page 8 of 66- 

generated from surrogate test species, which are intended to be representative of broad 

taxonomic groups, are used to extrapolate potential effects on a variety of species (receptors) 

included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature are used to evaluate potential direct effects of propoxycarbazonesodium to aquatic and terrestrial receptors. The open literature studies are located through EPA’s 

database ECOTOX (http://cfpub.epa.gov/ecotox/), which provides a source for locating single 

chemical toxicity data for aquatic life, terrestrial plants, and wildlife. 

2.3.2. Ecosystems Potentially at Risk 

The ecosystems at risk are often extensive in scope; therefore, it may not be possible to identify 

specific ecosystems at the screening level. In general terms, terrestrial ecosystems potentially at 

risk could include the treated site and areas immediately adjacent to the treated site that may 

receive drift, runoff, erosion, or discharged groundwater. These areas could include the treatment 

site itself, other cultivated fields, fencerows and hedgerows, meadows, fallow fields or 

grasslands, woodlands, riparian habitats, and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to or downstream from 

treated areas, and can include lentic systems, i.e., ponds, lakes and impoundments (reservoirs), 

and lotic systems (streams and rivers). Aquatic ecosystems supplied by groundwater, including 

cave ecosystems and areas supplied by seeps and springs, may be at risk from compounds that 

leach into the subsurface. For uses in coastal areas, aquatic habitat at potential risk includes 

marine and estuarine ecosystems. In evaluating aquatic exposure within water bodies, EFED 

considers the water column, sediment, and pore water as compartments of concern. 

Propoxycarbazone-sodium is not identified as a cause of impairment for any water bodies listed 

as impaired under section 303(d) of the Clean Water Act. No Total Maximum Daily Loads 

(TMDLs) or water quality criteria have been developed for propoxycarbazone-sodium2

. Office of 

Pesticide Programs (OPP) Aquatic Life Benchmarks3

 have not been established for 

propoxycarbazone-sodium. 

2.4. Assessment Endpoints 

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (species, community, or other entity) and its attribute or characteristics 

(USEPA, 1998). For propoxycarbazone-sodium, the ecological entities include the following: 

birds, amphibians, reptiles, mammals, freshwater fish and invertebrates, estuarine/marine fish 

and invertebrates, terrestrial plants, insects, and aquatic plants and algae. The attributes assessed 

for each of these entities may include growth, survival, and reproduction. 

The assessment endpoints are intended to reflect population sustainability and community 

 

2 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 3

 Office of Pesticide Programs’ Aquatic Life Benchmarks. 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm 
-Page 9 of 66- 

structure within ecosystems and hence relate back to ecosystems at risk. If risks are expected for 

given species/taxa based on the screening-level assessment, then risks might be expected to 

translate to higher levels of biological organization. 

2.5. Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure. The conceptual model is 

intended to provide a written description and visual representation of the predicted relationships 

between propoxycarbazone-sodium, potential routes of exposure, and the predicted effects for 

the assessment endpoint. The conceptual model consists of two major components: the risk 

hypotheses and a conceptual diagram (USEPA, 1998). 

The conceptual model used to depict the potential ecological risk associated with the proposed 

and existing uses of propoxycarbazone-sodium relies on previous assessments and the Agency’s 

current understanding of the environmental fate and ecological effects of the chemical. 

Consistent with the intended use of propoxycarbazone-sodium as an herbicide, potential risk to 

non-target terrestrial plants is expected. Effects on plants, which represent the primary producers 

in an ecosystem, may result in secondary effects on consumers. The model assumes that 

propoxycarbazone-sodium is capable of affecting terrestrial vertebrates and aquatic vertebrates 

and invertebrates, provided that environmental concentrations are sufficiently elevated as a result 

of existing uses (Figure 2.1). 

Based on the previous ecological risk assessments (USEPA, 2004b, 2008), risks at the highest 

label rate of propoxycarbazone-sodium are expected for non-listed and listed terrestrial and semiaquatic plant species and listed aquatic vascular plant species. Due to the potential risk from 

direct effects to these taxa, listed species in all taxa may potentially be affected indirectly due to 

alterations in their habitat (e.g., food sources, shelter, and areas to reproduce) if exposure to 

propoxycarbazone-sodium occurs. 

2.5.1. Risk Hypotheses 

For propoxycarbazone-sodium, the following ecological risk hypothesis is employed for the 

ecological risk assessment: 

Given the existing uses of propoxycarbazone-sodium and its environmental fate 

properties, there is possible acute and chronic exposure to non-target aquatic and 

terrestrial organisms. When used in accordance with the label, propoxycarbazonesodium may result in adverse effects upon the survival, growth, and reproduction of nontarget aquatic and terrestrial plants and animals. Bees and other pollinators may be at 

risk due to the systemic nature of the compound and the possibility that residues could be 

transported to pollen and nectar on which bees forage. To the extent to which terrestrial 

and/or aquatic plants are affected by the registered uses of the herbicide, other taxa may 
-Page 10 of 66- 

be indirectly affected via direct effects on primary productivity and loss of habitat. 

 

2.5.2. Conceptual Diagram 

The potential exposure pathways and effects of the proposed and existing uses of 

propoxycarbazone-sodium are depicted in Figure 2.1. Solid arrows depict the most likely routes 

of exposure and effects; dashed lines depict potential routes of exposure that are not considered 

likely for propoxycarbazone-sodium. 

Application methods for proposed and existing uses of propoxycarbazone-sodium involve 

ground (broadcast or hand-held spot treatment) and aerial applications. Ecological receptors that 

may be exposed to propoxycarbazone-sodium following such applications include terrestrial and 

semi-aquatic wildlife (i.e., mammals, birds, terrestrial-phase amphibians, terrestrial invertebrates, 

and reptiles) and plants. In addition, aquatic receptors (e.g., freshwater and estuarine/marine fish 

and invertebrates, aquatic-phase amphibians, and plants) may be exposed as a result of 

movement of propoxycarbazone-sodium via spray drift and runoff from the site of application. 

The conceptual framework for assessment of potential ecological risk associated with 

propoxycarbazone-sodium is depicted in Figure 2.1; potential endpoints, stressors, and 

ecological effects are identified based on this model. 

For terrestrial organisms, the primary route of exposure assessed at the screening level is the 

dietary route, via consumption of food items such as plant leaves or insects that have 

propoxycarbazone-sodium residues as a result of spraying. The assessment considers exposure of 

non-target terrestrial invertebrates through oral ingestion of residues and through contact, e.g., as 

a result of direct deposition or spray drift. Direct contact and root uptake are the major routes of 

exposure considered for terrestrial and wetland plants. 

Based on propoxycarbazone-sodium’s vapor pressure (7.1x 10-11 torr), it is not expected to 

readily volatilize, so this risk assessment does not take into account potential atmospheric 

transport in estimating environmental concentrations. The Screening Tool for Inhalation Risk 

(STIR) (see Section 2.6.1.2), which compares inhalation exposure estimates to available avian 

and mammalian toxicity data, also indicates that inhalation of vapor and spray drift are not of 

concern, so this assessment does not evaluate potential atmospheric transport in estimating 

environmental concentrations. Additionally, the Screening Imbibition Program (SIP) indicates 

that drinking water exposure may be a potential pathway of concern for wildlife due to the high 

solubility (42,000 mg/L); however, risks are unlikely due to the non-definitive toxicity endpoints 

for both birds and mammals and low application rates. The current assessment will consider 

potential chronic risk to wildlife through drinking water exposure qualitatively only. This 

assessment does not account for possible ingestion of propoxycarbazone-sodium residues by 

terrestrial animals via contaminated grit or preening activities, and does not evaluate potential 

uptake through dermal absorption. 

For aquatic assessments, the major routes of exposure for aquatic animal species are considered 

to be through the respiratory surface (gills) or the integument. Organisms in habitats supplied 

primarily by groundwater discharge (e.g., seeps, springs) may receive a different level of 

exposure than organisms in surface rivers, streams, lakes, and impoundments. Similar to 
-Page 11 of 66- 

terrestrial organisms, exposure of aquatic organisms to propoxycarbazone-sodium may also 

occur through ingestion of residues in sediment and forage. Propoxycarbazone-sodium is 

hydrophilic, with a log octanol-water partition coefficient (logKow) of -1.55. Therefore, 

propoxycarbazone-sodium residues are not expected to bioconcentrate in fish. 

Figure 2.1. Conceptual Model Depicting Potential Risks to Non-target Species from the Use of 

Propoxycarbazone-sodium. Solid arrows depict the most likely routes of exposure and effects; dashed lines depict 

potential routes of exposure that are not considered likely.

2.6. Analysis Plan 

2.6.1. Measures of Exposure 

2.6.1.1. Measures of Aquatic Exposure 

Measures of exposure to aquatic animals and plants are concentrations in surface water and 

benthic sediment pore water simulated by the Surface Water Concentration Calculator (SWCC, v 

1.106, May, 2014), used to generate estimated environmental concentrations (EECs) of 

propoxycarbazone-sodium that may occur from the chemical’s registered uses. The EECs used in 

assessment of acute risk are 1-in-10 year return frequency daily maximum values (referred to as 

“peak” values). For chronic risk assessment, mean concentrations over a specified duration are 

generated. In both cases, each modeled site is selected to represent a site expected to be more 

vulnerable to runoff than most locations where use may occur (e.g., based on the crop being 

grown). The SWCC simulates pesticide runoff from a treated area to an adjacent water body 

following applications, in addition to loadings that occur directly to the water as a consequence 

of spray drift. 

Stressor

Source/ 

Transport 

Pathways 

Direct Deposition Runoff 

Erosion 

Leaching 

(Infiltration/ 

Percolation 

Source/ 

Exposure 

Media 

Terrestrial Plants 

Terrestrial Invertebrates 

Terrestrial Plants 

Soil

Receiving 

Water 

Body/ 

Sediment

Groundwater 

Tested 

Exposure 

Route 

Ingestion Direct Contact 

Root Uptake Gill or Integument 

Uptake 

Receptors 

Attribute 

Changes 

Terrestrial 

Vertebrates & 

Invertebrates 

Terrestrial Plants 

Individual Animals: 

 Reduced survival and/or reproduction 

Aquatic Invertebrates 

Aquatic Vertebrates 

Individual Plants: 

 Seedling emergence 

 Vegetative vigor

Individual Animals: 

 Reduced survival 

and/or reproduction 

Plant Population: 

 Reduced population 

growth

Aquatic Plants 

Uptake/ 

Adsorption

Spray Drift Volatilization 

Atmospheric Transport

Propoxycarbazone-sodium 

Direct Contact 

Terrestrial 

Invertebrates 
-Page 12 of 66- 

2.6.1.2. Measures of Terrestrial Exposure 

Terrestrial wildlife could be exposed to propoxycarbazone-sodium via consumption of residues 

on food items from spray applications. For spray applications, the T-REX model (Terrestrial 

Residue EXposure model; v. 1.5.1; June 6, 2013b) is used to predict dietary exposure to 

propoxycarbazone-sodium residues on foliar surfaces and insects using the Kenaga nomogram as 

modified by Fletcher (Hoerger and Kenaga 1972, Fletcher et al. 1994). In this assessment, the 

default foliar dissipation half-life of 35 days was used for terrestrial modeling purposes. 

The TERRPLANT (v. 1.2.2; December 26, 2006) model is used to derive EECs relevant to 

terrestrial and wetland plants for the uses of propoxycarbazone-sodium. The model assumes that 

default fractions of the intended application will be transported to an adjacent field through 

runoff and spray drift. Measures of exposure to terrestrial plants are expressed as a fraction of the 

mass of the propoxycarbazone-sodium applied to a treated field. 

To characterize potential non-target plant exposure from spray drift alone, Tier 1 modules in 

AgDRIFT (v. 2.1.1, December 2011) were used to estimate how far off-site spray drift exposure 

might occur at a level known to cause adverse effects in terrestrial plant toxicity studies. Four of 

the five end-use product labels for propoxycarbazone-sodium specify that the products should be 

applied using nozzles and pressures that generate a Medium spray droplet size category. The 

Olympus® label differs from the others; it specifies that the product should be applied using 

nozzles and pressures that generate a Coarse spray droplet size category. The droplet size 

categories specified on the labels will be used for modeling in AgDRIFT. 

The Screening Tool for Inhalation Risk (STIR v.1.0, November 19, 2010) was used to calculate 

an upper-bound estimate of wildlife inhalation exposure using propoxycarbazone-sodium’s 

vapor pressure and molecular weight for vapor phase exposure as well as the maximum 

application rate and method of application for spray drift. STIR incorporates results from several 

toxicity studies including acute oral and inhalation rat toxicity endpoints obtained from the “sixpack” of core studies, which is a series of six guideline studies that are submitted to the 

Registration Division of the Office of Pesticide Programs for technical and formulated products 

of a pesticide (LD50 >5,000 mg/kg-bw/day, MRID 45012509; and inhalation LC50 >5.03 mg/L, 

MRID 45012505) as well as the most sensitive acute oral avian toxicity endpoint (bobwhite quail 

LD50 >2,000 mg/kg-bw, MRID 45012813). Based on the results of the STIR model (Appendix 

D), exposure through inhalation of spray drift or the vapor phase of propoxycarbazone-sodium is 

not determined to be a potential pathway of concern for either avian or mammalian species on an 

acute exposure basis. 

 

The analysis of the inhalation route in STIR does not consider that aggregation with other 

exposure pathways such as dietary, dermal, or drinking water may contribute to a total exposure 

that has a potential for effects to non-target animals. However, the Agency does consider the 

relative importance of other routes of exposure in situations where data indicate that pesticide 

exposures through other routes may be potentially significant contributors to wildlife risk 

(USEPA, 2004a). The risk characterization section (Section 4.2), discusses the impact of 

consideration of other routes of exposure that have been identified as potentially important and 

the degree of certainty associated with screening-level risk assessment conclusions. Detailed 
-Page 13 of 66- 

information about STIR v.1.0, as well as the tool, can be found on EPA’s website 

(http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial). 

The Screening Imbibition Program (SIP v.1.0, released June 15, 2010) was used to calculate an 

upper-bound estimate of wildlife drinking water exposure using propoxycarbazone-sodium’s 

solubility (i.e., 42,000 mg/L at 20o

C), and compared to the most sensitive acute and chronic 

avian and mammalian toxicity endpoints (see Table 3.13). Drinking water exposure alone was 

determined to be a potential pathway of concern for birds and mammals on both an acute and 

chronic exposure basis. For a sample of the output generated by SIP v.1.0, please see Appendix 

E. 

2.6.2. Measures of Effect 

Measures of effect are obtained from a suite of registrant-submitted guideline studies which were 

conducted with a limited number of surrogate test species. The test species are not intended to be 

representative of the most sensitive species but rather were selected based on their ability to 

thrive under laboratory conditions. Toxicity testing reported in this risk assessment utilizes 

surrogate species to represent all freshwater fish (2000+) and bird (680+) species in the U.S. In 

addition, the ECOTOX database (USEPA, 2009a) was searched in November 2014 to identify 

more ecological effects data for propoxycarbazone-sodium. No additional data were available 

that indicated greater sensitivity than those embodied in the registrant-submitted study endpoints. 

The acute measures of effect used in this screening-level assessment are the LD50 (Lethal Dose), 

LC50 (Lethal Concentration), EC50 (Effects Concentration), and IC50 (Inhibition Concentration). 

These are measures of acute toxicity which result in 50% of the respective effect in tested 

organisms. The endpoints for chronic measures of exposure are the NOAEC (No Observed 

Adverse Effects Concentration) and the NOAEL (No Observed Adverse Effects Level). Toxicity 

studies were submitted for freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates, aquatic and terrestrial plants, birds, mammals, and honey bees. The endpoints used 

for risk characterization were derived from studies which underwent review and were classified 

as “acceptable” (conducted under guideline conditions and considered to be scientifically valid) 

or “supplemental” (conditions deviated from guidelines but the results are considered to be 

scientifically valid). 

 2.6.3. Integration of Exposure and Effects 

The exposure and toxicity effects data are integrated in order to evaluate the risks of adverse 

ecological effects on non-target species. For the risk assessment of propoxycarbazone-sodium, 

the risk quotient (RQ) method is used to compare estimated exposure and measured toxicity 

values. The RQ method involves dividing estimated environmental concentrations (EEC) by 

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

of Concern (LOC) (USEPA, 2004a) (Table 2.2). The LOCs are used to indicate when 

applications of propoxycarbazone-sodium, as directed on the label, have the potential to cause 

adverse effects to non-target organisms. 
-Page 14 of 66- 

Table 2.2. Agency Risk Quotient (RQ) Metrics and Levels of Concern (LOC) Per Risk Class 

Risk Class Risk Description RQ LOC 

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures 

Peak EEC/LC501

 0.5 

Acute 

Restricted Use 

Potential for effects to animals from acute exposures 

Risks may be mitigated through restricted use classification Peak EEC/LC501

 0.1 

Acute Listed 

Species 

Listed species may be potentially affected by acute 

exposures 

Peak EEC/LC501

 0.05 

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures 

60-day EEC/NOAEC 

(fish) 1 

21-day EEC/NOAEC 

(invertebrates) 

Aquatic Plants 

Non-Listed Potential for effects to non-listed plants from exposures Peak EEC/LC501 1 

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC 1 

Terrestrial Animals (mammals and birds)2

Acute Potential for effects to non-listed animals from acute 

exposures 

EEC/LC50 (Dietary) 0.5 

EEC/LD50 (Dose) 

Acute 

Restricted Use 

Potential for effects to animals from acute exposures 

Risks may be mitigated through restricted use classification

EEC/LC50 (Dietary) 0.2 

EEC/LD50 (Dose) 

Acute Listed 

Species 

Listed species may be potentially affected by acute 

exposures 

EEC/LC50 (Dietary) 0.1 

EEC/LD50 (Dose) 

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures EEC/NOAEC 1 

Terrestrial Invertebrates3

Acute Potential for effects to bees and other insect pollinators 

from acute exposures to adults or larvae EEC/LD50 0.4 

Chronic Potential for effects to bees and other insect pollinators 

from chronic exposures to adults or larvae EEC/NOAEC 1.0 

Terrestrial and Semi-Aquatic Plants 

Non-Listed Potential for effects to non-target, non-listed plants from 

exposures 

EEC/ IC25 1 

Listed Plant Potential for effects to non-target, listed plants from 

exposures 

EEC/ NOAEC 

1 

EEC/ IC05

1 LC50 or EC50. 2

 EEC based on upper bound Kenaga nomogram values for foliar exposure. 

3

 USEPA et al., 2014. Guidance for Assessing Pesticide Risks to Bees. 

The Agency uses the probit dose-response relationship as a tool for providing additional 

information on the potential for acute direct effects to individuals from listed species and aquatic 

animals that may indirectly affect the listed species of concern (USEPA, 2004a). Individual 

effect probabilities are calculated based on a Microsoft® Excel spreadsheet tool IECV1.1 

(Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP, Environmental 

Fate and Effects Division (June 22, 2004). These calculations are not presented in this 
-Page 15 of 66- 

assessment due to the lack of definitive acute toxicity endpoints across all taxonomic groups for 

aquatic and terrestrial animals. 

3. Analysis 

3.1 Use Characterization 

Propoxycarbazone-sodium is a sulfonyl-amino-carbonyl-triazolinone herbicide used for the 

selective post-emergence control of grasses and broadleaf plants in wheat, triticale, rangeland, 

pastures, and Conservation Reserve Program land. It can be applied either by aerial or ground 

(broadcast or hand-held spot treatment) methods as a pre-plant, pre-emergence, or postemergence application. The only commercial available formulation is water dispersible granules 

(dry flowable). There are currently six active Section 3 registrations for propoxycarbazonesodium, including one technical, OlympusTM MKH 6561 Technical (EPA Reg No. 264-808). The 

five end-use products include Olympus® 70% Water Dispersible Granular Herbicide (EPA Reg 

No. 264-809), OlympusTM Flex Herbicide (EPA Reg No. 264-833), OlympusTM Rangeland

Herbicide (EPA Reg No. 264-1074), RimfireTM Herbicide (EPA Reg No. 264-847), and 

RimfireTM Max Herbicide (EPA Reg No. 264-1099). Three of the currently registered 

propoxycarbazone-sodium products for use on wheat and triticale (OlympusTM Flex, RimfireTM, 

and RimfireTM Max) contain mesosulfuron-methyl as a second active ingredient. Mesosulfuronmethyl use will not be assessed in this document. 

Based on available proprietary usage data, the predominant use of propoxycarbazone-sodium is 

on winter wheat (USEPA, 2014a). According to the Screening Level Usage Analysis (SLUA) 

provided by the Biological and Economic Analysis Division (BEAD), between 2004 and 2012 an 

average of 30,000 lbs a.i./yr was used on winter wheat and 3,000 lbs a.i./yr was used on spring 

wheat in the United States (USEPA, 2014b). The SLUA reports that a maximum of 5% of winter 

and spring wheat crop acres were treated with propoxycarbazone-sodium. These data do not 

include non-crop uses. Application rates are similar for all use patterns. The highest annual and 

single maximum application rates are 0.0525 lb a.i./A. 

Error! Reference source not found.Table 3.1 lists the maximum use patterns for the labeled use 

sites. The table is based on the “EFED Table 1 Report,” which is a part of the Label Use Report 

Package created by BEAD in support of Registration Review (USEPA, 2014b). 
-Page 16 of 66- 

Table 3.1. Propoxycarbazone-sodium Maximum Application Rates 

Use 

Single Max 

Application 

Rate 

(lbs a.i./A) 

Max 

Application 

Rate per 

Crop Cycle 

(lbs a.i./A) 

Max 

Application 

Rate per 

Year 

(lbs a.i./A) 

Min 

Application 

Retreatment 

Interval 

(days) 

Max # of 

Applications 

Per Year 

Application 

Methods 

Agricultural Fallow 

/ Conservation 

Reserve

0.0525 0.0525 0.0525 NA 1 

Aerial, 

ground, spot 

treatment 

Pastures 0.0525 0.0525 0.0525 NA 1 

Aerial, 

ground, spot 

treatment 

(hand-held) 

Rangeland 0.0525 0.0525 0.0525 NA 1 

Aerial, 

ground, spot 

treatment 

(hand-held) 

Triticale 0.0395 NS 0.0395 NA 1 Aerial, 

ground 

Wheat 0.0395 0.0525 0.0525 

Fall followed 

by spring 

applications 

21 Aerial, 

ground 

NS=not specified; NA=not applicable 

1

 Applications may be split evenly at 0.0263 lbs a.i./A in the fall followed by an application at the same rate in the 

spring. The maximum rate in the fall is 0.0395 lbs a.i./A, which can be followed by an application of 0.0130 lbs 

a.i./A in the spring. 

3.2. Exposure Characterization 

3.2.1. Environmental Fate and Transport Characterization 

The chemical and environmental fate characteristics of propoxycarbazone-sodium are listed in 

Table 3.2 and are discussed in greater detail in the following sections. 

Table 3.2. Chemical Properties and Environmental Fate Parameters of Propoxycarbazone-sodium 

Parameter Value Source

Selected Physical/Chemical Parameters 

Molecular mass (molecular formula) 420 g/mol (C15H17N4O7SNa ) (Calculated) 

Vapor pressure (20 °C) 7.1x 10-11 torr Product Chemistry 

Aqueous solubility (20°C, pH 7) 42,000 mg/L 

Henry’s Law Constant (20°C) 9.35x10-16 atm-m3/mol (Calculated) 

Log octanol-to-water partition coefficient (log Kow) 

(20°C, pH 7) 

-1.55 Product Chemistry 

Dissociation constant (pKa) 2.1 

Persistence in Water

Hydrolysis half-life (20°C) pH 4: 110 days, pH 7: 495 days, 

pH 9: 408 days 

MRID 45012733 

MRID 45012740 

pH 4: 154 days, pH 7: 433 days, 

pH 9: 385 days 

MRID 45012724 

MRID 45012725 
-Page 17 of 66- 

Parameter Value Source

Aqueous photolysis half-life (20°C) (pH 7) 93.5 days 

37 days 

MRID 45012703 

MRID 45012702 

Persistence in Soil 

Photodegradation half-life on soil 70 days 

38 days 

MRID 45012729 

MRID 45012728 

Aerobic soil metabolism half-life (20°C) 77 days MRID 45012720 

MRID 45012736 

103 days MRID 45012723 

21 days, 16 days, 83 days MRID 45012721 

MRID 45012735 

8.7 days, 46.5 days, 223.6 days MRID 45012722 

MRID 45012736 

Aerobic aquatic metabolism half-life (20 oC) 110 days, 107 days, 193 days, 210 days MRID 4512704 

Anaerobic aquatic metabolism half-life (20 °C) 1155 days MRID 45012708 

MRID 45012707 

Mobility

Freundlich Adsorption coefficient (Kd) 

 

 (Koc) (20 o

C) 

0.2504, 0.4968, 0.2239, 0.2134, 1.0747 

L/kg 

10.1, 18.7, 26, 57.7, 66.7 

MRID 45012634 

Terrestrial Field Dissipation 

Field Dissipation half-life US Soils 22.4 days 

US Soil 6.8 days 

US Soil 44.4 days 

European Soil 12, 15, 16, 22, 29, 34, 

and 56 days 

MRID 45012716 

MRID 45012719 

MRID 45012715 

MRID 45012738 

Fish Bioconcentration 

Not required – Kow (0.028) is less than 1,000 

3.2.1.1. Transport and Mobility 

Propoxycarbazone has high water solubility (42,000 mg/L in pH 7 water) and a low vapor 

pressure (7.1 x 10-11 mmHg at 20o

C). The calculated Henry's Law Constant of 9.35 x 10-16 atmm3/mol) indicates that propoxycarbazone is not expected to be volatile under field conditions 

and from water. The high water solubility and low soil partitioning coefficients (Kd = 0.22 to 

1.07) indicate that it is very mobile in soil. Due to its low Kow value of 0.028, bioaccumulation 

is not likely to occur. 

3.2.1.2. Degradation 

Propoxycarbazone hydrolyzes at relatively slow rates, the half-lives at pH 7 are 495 and 433 

days, with an average of 464 days. In pH 7 buffered water, the photolysis half-lives of 

propoxycarbazone are 93.5 and 37 days, with an average of 65.25 days. For photodegradation on 

soil, the half-lives are 70 and 38 days, with an average of 54 days. Several aerobic soil 

metabolism studies show a range of half-life values: 8.7 days, 16 days, 21 days, 46.5 days, 77 
-Page 18 of 66- 

days, 83 days, 103 days, and 224 days. For aerobic aquatic metabolism study, the half-lives are 

107 days, 110 days, 193 days, and 210 days. Anaerobic aquatic metabolism has the longest halflife of 1155 days. 

Terrestrial field dissipation studies were conducted in the U.S. (Washington, Utah, and Kansas) 

and in Europe (Germany, France, and the UK). Both cropped and non-cropped studies were 

conducted. Leaching of propoxycarbazone-sodium was not observed below the 6- to 12- inch 

layer. Volatilization was not measured, but was not expected based on the low vapor pressure. 

Run-off was not measured. Field dissipation half-lives were in the range of 12 to 56 days. 

3.2.1.3. Transformation Products 

Major identified environmental degradates of propoxycarbazone are saccharin (MKH 7284), 

MKH 6561 sulfonamide methyl ester, N-methyl propoxy triazolinone (MKH 7017), 4-hydroxy 

saccharin, MKH 6561 carboxylic acid (MKH 8394), MKH sulfonamide acid (MKH 7283), Nmethyl propoxy triazolinones amide, and carbon dioxide. The chemical names, structures, routes 

of formation, and maximum amounts formed are listed in Table 3.3. 

The propoxycarbazone-carboxylic acid degradate (MKH 8394) results from the loss of a methyl 

ester group but has the intact sulfonylurea (SU) bridge. This degradate was stable in aerobic and 

anaerobic aqueous metabolism studies, forming 50% or more of the applied test compound at the 

end of 100-day or 365-day experiments. 

There are two sets of degradates that result from the cleaving of the SU bridge. These include the 

triazolinones, and the sulfonamide/saccharins. The former set includes N-methyl propoxy 

triazolinone amide and N-methyl propoxy triazolinone (MKH 7017), which was a major 

degradate in all soil metabolism studies. The latter set includes MKH 6561 sulfonamide methyl 

ester (STJ 4934), sulfonamide acid (MKH 7283), saccharin (MKH 7284), and 4-

hydroxysaccharin. All of these were major metabolites in soil or aquatic metabolism 

experiments. With the exception of 4-hydroxysaccharin, all are of equal or greater mobility than 

the parent compound. 

Acute toxicity tests were performed with two of propoxycarbazone-sodium's major degradates, 

MKH 6561 carboxylic acid (MKH 8394) and N-methyl propoxy triazolinone (MKH 7017), and 

the LC50s from these studies were determined to be greater than the limit concentration for both 

freshwater fish and invertebrates (see Section 3.3.1 for details on the toxicity tests). The same 

degradates, MKH 8394 and MKH 7017, were tested on vascular and non-vascular aquatic plants 

and determined to be at least two orders of magnitude less toxic than the parent compound. 

Toxicity data on the other major degradates MKH 6561 sulfonamide methyl ester (STJ 4934), 

sulfonamide acid (MKH 7283), saccharin (MKH 7284), and 4-hydroxysaccharin either are not 

available or indicate that they are not of concern.4 

 

4

 Acute toxicity studies were conducted on the earthworm for MKH 7284(1,2-benzoisothiazol-3-(2H)-one,1,1-

dioxide) and STJ 4934 (2-carbomethyoxybenxenesulfonamide) (MRID 45012836 and 45012835). Median lethal 

concentrations were greater than 1000 mg/kg for both metabolites and the parent compound. 
-Page 19 of 66- 

Degradates that do not contain the triazolinone moiety are not considered stressors of concern in 

this assessment based on the lack of structural similarity to the parent compound. Degradates that 

do contain the triazolinone moiety are not considered stressors of concern in this assessment 

based on results of the toxicity studies described above. While the triazolinone degradates do 

appear to be more toxic to freshwater aquatic invertebrates than the parent compound, the acute 

toxicity endpoints are non-definitive for both the degradates and the parent compound. 

Additionally, EECs for the parent compound are at least four orders of magnitude less than the 

minimum possible toxicity values for fish and aquatic invertebrates and are not expected to be 

significantly higher if the triazolinone degradates were included. Therefore, risks are evaluated 

based on estimated exposure to the parent compound only in this assessment. 
-Page 20 of 66- 

Table 3.3. Propoxycarbazone-sodium and Its Environmental Transformation Products 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID 

%

PARENT

Propoxycarbazonesodium MKH 6561 

Methyl 2-(4,5-dihydro-4-methyl-5-oxo3-propoxy-1H-1,2,4-triazol-1-yl) carboxamidosulfonylbenzoate, sodium salt CAS Reg. No. 181274-15-7 (sodium salt); 145026-81-9 (acid) Formula: C15H18N4O7S Na 

MW: 420 g/mol (sodium salt)  398 g/mol (acid, MKH 5554)

MAJOR TRANSFORMATION PRODUCTS

Saccharin MKH 7284 

1,2-Benzisothiazol-3(2H)-one,1,1-dioxide Formula: C7H5NO3S 

MW: 183 g/mol

Hydrolysis 45012733 45012740

 

Photodegradation on 

soil 45012729 

Photolysis 45012702 2

Aerobic soil 

4501272045012736 4501272245012736 2

MKH 6561 sulfonamide methyl ester STJ 4934 

2-carbomethoxybenzene-sulfonamide Formula: C8H9NO4S 

MW: 215 g/mol

Hydrolysis 45012733 45012740 1

Photolysis 45012702 

Photodegradation 

on soil 45012729 

Aerobic soil 

4501272045012736 4501272245012736 

Aerobic Aquatic 45012704 1
-Page 21 of 66- 

N-methyl propoxy triazolinone MKH 7017 

3H-1,2,4-Triazol-3-one, 2,4-dihydro-4-methyl-5-propoxy Formula: C6H11N3O2

MW: 157 g/mol

Hydrolysis 45012724 45012725

1

 

4

Photolysis 45012703 1

Photodegradation 

on soil 45012728 

Aerobic soil 

45012723 24501272145012735

4

5

Anaerobic Aquatic 45012708 2

Aerobic Aquatic 45012704 3

4-Hydroxy Saccharin 1,2-Benzisothiazol-3(2H)-one,4-

hydroxy-,1,1-dioxide Formula: C7H5NO4S 

MW: 199 g/mol Aerobic soil 

4501272045012736 1

4501272245012736 2

MKH 6151 Carboxylic Acid MKH 8394 

Benzoic acid, 2-(((4,5-dihydro-4-methyl-5-oxo-3-propoxy-1H-1,2,4-triazol-1-yl) carbonyl)amino)sulfonyl Formula: C14H16N4O7S 

MW: 384 g/mol

Aerobic soil 

4501272045012736 

4501272245012736 

Anaerobic Aquatic 

45012708 8

45012707 8

Aerobic Aquatic 45012704 7
-Page 22 of 66- 

Bolded values are those >10%, indicating a major degradate. ND=not detected

MKH 6151 Sulfonamide Acid MKH 7283 

Benzoic acid, 2-(aminosulfonyl) Formula: C7H7NO4S 

MW: 201 g/mol

Aerobic soil 45012722 45012736 

Anaerobic Aquatic 45012707 2

Aerobic Aquatic 45012704 1

N-Methyl propoxy triazolinones amide 

3H-1,2,4-Triazol-3-one-2-carboxamide2,4-dihydro-4-methyl-5-propoxy Formula: C7H12N4O3

MW: 200 g/mol

Aerobic soil 

45012723 14501272145012735 
-Page 23 of 66- 

3.2.2. Measures of Aquatic Exposure 

3.2.2.1. Aquatic Exposure Modeling 

The EECs for propoxycarbazone-sodium in surface water were generated based on maximum 

use rates (Table 3.1). Simulations were conducted using the SWCC model (v 1.106, May, 2014). 

The SWCC simulates pesticide runoff from a treated area to an adjacent water body following 

applications, in addition to loadings that occur directly to the water as a consequence of spray 

drift. The SWCC scenarios assume a standard 1-hectare, 2-meter depth pond (static water body) 

into which a 10-hectare field drains (see http://www.epa.gov/oppefed1/models/water/). An 

example of SWCC model inputs and output is included in Appendix A. 

The SWCC uses the Pesticide Root Zone Model (PRZM v5.0+, May 6, 2014) and the Varying 

Volume Water Body Model (VVWM, May 6, 2014, a replacement for the older EXAMS model). 

The PRZM modeling scenario is the basic file that describes the local or regional climatological 

information, soil hydrology, soil characteristics, crop characteristics, and the pesticide properties 

necessary to determine pesticide loadings to surface water. This basic file constitutes the first 

part of the “exposure scenario.” It simulates the processes in the agricultural field, such as runoff 

and erosion, on a daily time step. The runoff and erosion flux output data from PRZM are used 

as chemical loadings to the VVWM, which simulates surface water, in order to predict the EECs. 

The VVWM is conceptually similar to the current EXAMS-based model in that both are 2-

compartment models driven by first-order processes. It simulates the U.S. EPA standard water 

bodies (i.e., farm pond) but with greater efficiency and flexibility for incorporation into a user 

interface. The VVWM also allows for variations in water body volume on a daily basis due to 

runoff, precipitation, and evaporation. Temperature, wind speeds, and pesticide dissipation 

processes are also allowed to vary daily. EECs were determined using the standard pond scenario 

which describes a vulnerable surface waters scenario for the VVWM component of the modeling 

exercise. 

3.2.2.2. Aquatic Modeling Inputs 

For aquatic exposure, modeling was conducted for parent propoxycarbazone-sodium only. Halflives used for modeling are presented in Table 3.4. Application parameters were chosen based 

on the likely method of application at the maximum application rate as indicated in the label 

instructions. Chemical property and model input values (Table 3.4) were chosen according to the 

current Input Parameter Guidance (USEPA, 2009c).

Based on the maximum labeled application rates (Table 3.1), modeling was conducted for three 

maximum annual rate scenarios: (1) a single application rate of 0.0525 lb a.i./A for agricultural 

fallow/conservation reserve, pastures, and rangeland, (2) a fall application of 0.02625 lb a.i./A, 

followed by a spring application of 0.02625 lb a.i./A for wheat, and (3) a fall application of 

0.0395 lb a.i./A in the fall followed by 0.0130 lb a.i./A in the spring for wheat. Pesticide 

application inputs are presented in Table 3.5. 

The scenarios listed in Table 3.6 are those currently approved for Tier II surface water modeling 

which most closely represent the current and proposed uses for propoxycarbazone-sodium. There 

are two rangeland modeling scenarios in the SWCC database. They are for California rangeland 
-Page 24 of 66- 

hay and Texas Barton Springs range. For the wheat and triticale (cereal grains) use sites, two 

applicable scenarios are available, for North Dakota and Texas. For agricultural fallow land, the 

Florida cabbage scenario is used to mimic the fallow conditions at a potential high rainfall area. 

Table 3.4. Environmental Fate Data Used for Propoxycarbazone-sodium Aquatic Exposure Inputs 

Parameter Value Source

Molecular Weight (g/mol) 420 C15H17N4O7SNa 

Water Solubility (mg/L) at 20oC 42000 

Product Chemistry Vapor Pressure (torr) 7.1 x 10-11

Hydrolysis half-life (days) @pH 7 495 (maximum value) MRID 45012733, 45012740 

Aqueous photolysis half-life (days) 93.5 (maximum value) MRID 45012703 

Aerobic soil metabolism half-life 

(days) 

107 (upper 90th percentile on eight values: 

77, 103, 21, 16, 83, 8.7, 46.5, and 224) 

MRID 45012720, 45012736 

MRID 45012723, 45012721 

MRID 45012735, 45012722 

MRID 45012736 

Aerobic aquatic metabolism halflife (days) 199 (upper 90th percentile on four values: 

110, 107, 193, and 210) MRID 4512704 

Anaerobic aquatic metabolism halflife (days) 1155 MRID 45012708 

MRID 45012707 

Adsorption coefficients (Kd) 0.4518 (Mean of five values: 0.2504, 

0.4968, 0.2239, 0.2134, and 1.0747) MRID 45012634 

Table 3.5. Application Information for Propoxycarbazone-sodium Aquatic Exposure Inputs 

Model Input Variable Input Value Comments 

Application Date(s) 

December 1 for California Rangeland Hay 

April 1 for Texas Barron Spring Range 

April 1 and November 16 for North Dakota Wheat 

June 16 and October 1 for Texas Wheat 

February 22 for Florida Cabbage 

Post-emergence (after 

emergence date) 

Fallow – 7 days after 

harvest 

Maximum Application Rate 

(maximum) and Number of 

Application 

1 @ 0.0525 lb a.i./acre 

Agricultural fallow/ 

Conservation reserve, 

Pasture, and Rangeland 

uses 

2 @ 0.02625 lb a.i./acre 

1 @ 0.0395 lb a.i./acre + 1 @ 0.0130 lb a.i/acre Triticale and Wheat uses 

Application method, 

App. Efficiency / Spray Drift 

Ground, 0.99 / 0.062 USEPA, 2013 Aerial, 0.95 / 0.125 

Table 3.6. SWCC Modeling Scenarios for Propoxycarbazone-sodium 

Modeling Scenario Met. File 

(.dvf) Emergence Date Maturation Date Harvest Date 

California Rangeland Hay 23232 Nov. 1 April 1 May 1 

Texas Barton Springs Range 13958 March 1 June 15 Nov. 15 

North Dakota Wheat 14914 Oct. 16 April 30 June 17 

Texas Wheat 13958 May 16 July 25 August 5 

Florida Cabbage 12842 Oct. 16 Feb. 8 Feb. 15 
-Page 25 of 66- 

3.2.2.3. Estimated Environmental Concentrations in Surface 

Water 

The EECs listed in Table 3.7 reflect daily 1-in-10 year return frequency (i.e., “peak”) surface 

water concentrations based on maximum application rates for label uses of propoxycarbazonesodium. 

Table 3.7. Propoxycarbazone-sodium Screening-level EECs 

PRZM Scenario Type of 

Application 

1-in-10-year Peak 

Exposure (μg/L)

1-in-10-year 

21-day Average 

Exposure (μg/L)

1-in-10-year 

60-day Average 

Exposure (μg/L) 

CA Rangeland Hay 

Aerial 0.847 0.824 0.676 

Ground 0.631 0.613 0.490 

TX Barton Springs Range 

Aerial 1.03 0.978 0.934 

Ground 0.871 0.826 0.779 

ND Wheat 

(2 @ same rate) 

Aerial 0.814 0.797 0.755 

Ground 0.600 0.587 0.556 

ND Wheat 

(different rates) 

Aerial 1.00 0.982 0.930 

Ground 0.781 0.764 0.723 

TX Wheat 

(2 @ same rate) 

Aerial 2.29 2.19 2.03 

Ground 2.24 2.14 1.98 

TX Wheat 

(different rates) 

Aerial 1.96 1.82 1.68 

Ground 1.88 1.76 1.60 

FL Cabbage 

Aerial 1.08 1.04 0.853 

Ground 0.905 0.867 0.697 

Bolded values are the maximum EECs for use in risk estimation (i.e., RQ calculations). 

3.2.2.4. Monitoring Data 

Propoxycarbazone is not an analyte in any of the following water monitoring programs: the 

California Department of Pesticide Regulation (CDPR) surface water database5, the USGS 

NAWQA surface and ground water database6

, the USEPA STORET Data Warehouse7, and the 

USDA Pesticide Data Program drinking water monitoring analyses8

. 

3.2.3. Measures of Terrestrial Exposure 

 

3.2.3.1. Ingestion of Foliar Residues by Birds and Mammals 

Terrestrial wildlife exposure estimates are typically calculated for birds and mammals, 

emphasizing a dietary exposure route for uptake of pesticide active ingredients. Avian exposures 

 

5 http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm

6 http://cida.usgs.gov/nawqa_queries_public/

7 http://www.epa.gov/storet/

8 http://www.ams.usda.gov/AMSv1.0/ams.fetchTemplateData.do?template=TemplateG&navID=&rightNav1=& 

topNav=&leftNav=ScienceandLaboratories&page=PDPDownloadData/Reports&resultType=&acct=pestcddataprg
-Page 26 of 66- 

are considered surrogates for exposures to terrestrial-phase amphibians and reptiles. For 

exposure to terrestrial organisms, such as birds and mammals, pesticide residues on food items 

are estimated based on the assumption that organisms forage on areas treated with the pesticide. 

For propoxycarbazone-sodium, application methods for the registered uses include broadcast and 

directed spray of liquid formulations for all use sites. 

T-REX (v. 1.5.2) is used to calculate dietary and dose-based EECs of propoxycarbazone-sodium 

residues on food items for mammals and birds via proposed spray applications of the labeled 

uses. Input values for deriving EECs in T-REX are located in Table 3.8. Upper-bound Kenaga 

nomogram values are used to derive EECs for propoxycarbazone-sodium exposures to terrestrial 

mammals and birds (Table 3.9), based on a 1-year time period. Consideration is given to 

different types of feeding strategies for mammals, including herbivores, insectivores and 

granivores. Dose-based exposures are estimated for three weight classes of birds (20 g, 100 g, 

and 1000 g) and for three weight classes of mammals (15 g, 35 g, and 1000 g). Chemical specific 

foliar dissipation half-life data were not identified, so the default value of 35 days is used in 

modeling. 

Table 3.8. Input Parameters for Deriving Terrestrial EECs for Propoxycarbazone-sodium Labeled Uses (TREX) 

Proposed Use Application Rate 

(lbs a.i./A) 

Number of 

Applications 

Minimum 

Reapplication 

Interval (days) 

Foliar Dissipation 

Half-Life (days) 

Agricultural Fallow / 

Conservation Reserve, 

Pastures, and Rangeland1 0.0525 1 NA 

35 Triticale 0.0395 1 NA 

Wheat 1st: 0.0395 

2nd: 0.0130 2 1822

1

 Terrestrial exposure modeling for these uses is combined because the input parameters are identical. 2

 The maximum rate in the fall is 0.0395 lbs a.i./A, which can be followed by an application of 0.0130 lbs a.i./A in 

the spring. For terrestrial exposure modeling, this use pattern is more conservative than two applications at 0.0263 

lbs a.i./A. The minimum reapplication interval is not defined on the label, but is assumed to be 6 months for 

modeling purposes based on the seasonal application pattern. 

Because of the length of the re-application interval between the fall and spring applications of 

propoxycarbazone-sodium to wheat, the second application does not impact the EECs calculated 

in T-REX. T-REX calculates EECs at the peak residue concentration. In the modeled scenario, 

sufficient degradation occurs between the first and second application that the second application 

does not affect the peak residue concentrations. Therefore, T-REX results and assessment of risk 

to terrestrial organisms for wheat and triticale uses will be combined in the remainder of this 

assessment based on the single maximum 0.0395 lb a.i./A application rate. 

Differences in exposures between ground and aerial applications are not assessed with the 

current model. Therefore, terrestrial risk conclusions for the registered uses apply to both ground 

and aerial exposures resulting from application of propoxycarbazone-sodium. An example of 

output from the T-REX model is provided in Appendix B. 
-Page 27 of 66- 

Table 3.9. T-REX Calculated EECs as Food Residues for Terrestrial Animals from Propoxycarbazonesodium Labeled Uses 

Food Type

Dietary-Based EEC 

(ppm) 

(Mammals and 

Birds) 

Dose-Based EEC for Birds 

(mg/kg-bw)

Dose-Based EEC for Mammals 

(mg/kg-bw)

All Size Classes Small 

(20 g) 

Medium 

(100 g) 

Large 

(1000 g) 

Small 

(15 g) 

Medium 

(35 g) 

Large 

(1000 g) 

Agricultural Fallow / Conservation Reserve, Pastures, and Rangeland

Short grass 12.60 14.35 8.18 3.66 12.01 8.30 1.93 

Tall grass 5.78 6.58 3.75 1.68 5.51 3.81 0.88 

Broadleaf plants 7.09 8.07 4.60 2.06 6.76 4.67 1.08 

Fruits/pods 0.79 0.90 0.51 0.23 0.75 0.52 0.12 

Arthropods 4.94 5.62 3.21 1.43 4.71 3.25 0.75 

Seeds 0.79 0.20 0.11 0.05 0.17 0.12 0.03 

Triticale and Wheat

Short grass 9.48 10.80 6.16 2.76 9.04 6.25 1.45 

Tall grass 4.35 4.95 2.82 1.26 4.14 2.86 0.66 

Broadleaf plants 5.33 6.07 3.46 1.55 5.08 3.51 0.81 

Fruits/pods 0.59 0.67 0.38 0.17 0.56 0.39 0.09 

Arthropods 3.71 4.23 2.41 1.08 3.54 2.45 0.57 

Seeds 0.59 0.15 0.09 0.04 0.13 0.09 0.02 

3.2.3.2. Exposure to Insect Pollinators 

The Guidance for Assessing Pesticide Risks to Bees (USEPA et al., 2014) provides equations for 

the calculation of EECs for bees. The Tier I exposure method is intended to account for the 

major routes of pesticide exposure that are relevant to bees (i.e., through diet and contact). 

Exposure routes for bees differ based on application type. Bees foraging in a field treated with a 

pesticide through foliar spray, such as propoxycarbazone-sodium, could potentially be exposed 

to the pesticide through direct spray as well through consuming contaminated food. Foraging 

honey bees may also be exposed to pesticides via consumption of water from surface water, 

puddles, dew droplet formation on leaves and guttation fluid; however, the Tier I exposure 

method does not include quantification of exposures via these routes. 

The EECs for foliar applications of propoxycarbazone-sodium are calculated below.9 

Adult Contact EEC = 0.0525 lbs a.i./A * 2.7 μg a.i./bee = 0.14 μg a.i./bee 

Adult Dietary EEC = 0.0525 lbs a.i./A * 110 μg a.i./g * 0.292 g/day = 1.7 μg a.i./bee/day 

Larval Dietary EEC = 0.0525 lbs a.i./A * 110 μg a.i./g * 0.124 g/day = 0.72 μg a.i./bee/day 

Further analysis of potential exposure routes to honey bees will be considered following the 

receipt of additional data (see Section 8). 

 

9 Based on food consumption rates for larvae (0.124 g/day) and adult (0.292 g/day) worker bees and concentration in 

pollen and nectar. 
-Page 28 of 66- 

3.2.3.3. Runoff and Spray Drift to Terrestrial and Semi-Aquatic 

Plants 

Exposure of non-target terrestrial and semi-aquatic (wetland) plant species is estimated using 

OPP’s TERRPLANT (v. 1.2.2) model. Loading via spray drift to dry, non-target, adjacent areas 

is assumed to occur from one acre of treated land to one acre of the non-target area. Runoff is 

also expected to be a source of pesticide loading to non-target areas. TERRPLANT calculates 

EECs as a function of application rate, solubility, and default assumptions regarding spray drift. 

The default spray drift assumptions are: 1% of the application rate (mass per acre) for ground 

spray applications and 5% for aerial spray applications (USEPA, 2006). The EECs for terrestrial 

and semi-aquatic plants for a single application of propoxycarbazone-sodium at the maximum 

labeled rates for representative uses are presented in Table 3.10 (see example output in 

Appendix C). 

Table 3.10. EECs for Terrestrial and Semi-Aquatic Plants Near Propoxycarbazone-sodium Use Areas 

Crop 

Single Max. 

Application 

Rate 

(lbs a.i./A) 

EECs (lbs a.i./A) 

Ground Aerial 

Dry 

Areas 

(Total) 

SemiAquatic 

Areas 

(Total) 

Spray 

Drift 

Dry 

Areas 

(Total) 

SemiAquatic 

Areas 

(Total) 

Spray 

Drift 

Agricultural Fallow / 

Conservation 

Reserve, Pastures, 

and Rangeland

0.0525 0.0032 0.0268 0.0005 0.0053 0.0289 0.0026 

Triticale and Wheat 0.0395 0.0024 0.0201 0.0004 0.0040 0.0217 0.0020 

3.3. Ecological Effects Characterization 

The ecological effects characterization for propoxycarbazone-sodium is based upon registrantsubmitted toxicity data for propoxycarbazone-sodium TGAI, degradates, and formulations. The 

most sensitive endpoints used for risk assessment are summarized briefly in Sections 3.3.1 and 

3.3.2. Ecotoxicity data submitted for propoxycarbazone-sodium degradates on aquatic organisms 

indicate that these degradates are approximately equally or less toxic than parent 

propoxycarbazone-sodium. 

The results of a 2014 review of the Ecological Incident Information System (EIIS) are described 

in Section 3.3.3 (USEPA, 2009b). A search of the publically-available ECOTOX database in 

November 2014 yielded no data other than those obtained from registrant-submitted guideline 

studies described below. 

3.3.1. Aquatic Effects Characterization 

3.3.1.1. Toxicity to Aquatic Animals

A summary of data on toxicity to aquatic vertebrates and invertebrates for technical grade 

propoxycarbazone-sodium and transformation products is presented in Table 3.11. All acute 
-Page 29 of 66- 

studies on the parent compound were limit tests with no mortality or sublethal effects observed. 

No effects were observed in any of the chronic studies. 

The acute studies on propoxycarbazone-sodium degradates also showed no mortality or sublethal 

effects to freshwater fish, but did show some effects on daphnids. Clinical signs of toxicity and 

approximately 10% immobilization were observed at the top concentration tested for both 

metabolites 7017 and 8394. 

Table 3.11. Summary of Available Toxicity Data for Aquatic Animals Exposed to Propoxycarbazone-sodium 

and its Degradates 

Taxonomic 

Group 

Study 

Type 

Test 

Substance 

(% a.i.) 

Surrogate Species 

Toxicity Value 

measured mg a.i./L 

(Acute Toxicity Category) 

MRID and 

Study 

Classification 

Aquatic Vertebrates 

Freshwater 

fish 

Acute 

TGAI 

(97.7%) 

Rainbow trout 

(Oncorhynchus 

mykiss) 

96-hr LC50 >77.2 

(Slightly toxic to Practically 

non-toxic) 

45012809 

Acceptable 

TGAI 

(98.0%) 

Bluegill sunfish 

(Lepomis 

macrochirus) 

96-hr LC50 >94.2 

(Slightly toxic to Practically 

non-toxic) 

45012806 

Acceptable 

Metabolite 

7017 (99.8%) 

96-hr LC50 >98.7 

(Slightly toxic to Practically 

non-toxic) 

45012827 

Acceptable 

Metabolite 

8394 (99.8%) 

96-hr LC50 >87.7 

(Slightly toxic to Practically 

non-toxic) 

45012828 

Acceptable 

Chronic 

(Early-life 

Stage) 

TGAI 

(97.7%) 

Fathead minnow 

(Pimephales 

promelas) 

35-d NOAEC = 105 

35-d LOAEC >105 

No effects observed 

45012817 

Supplemental 

Estuarine/ 

marine fish 

Acute TGAI 

(97.7%) 

Sheepshead Minnow 

(Cyprinodon 

variegatus) 

96-hr LC50 >108 

(Practically non-toxic) 

45012810 

Supplemental 

Chronic No data available 

Aquatic Invertebrates 

Freshwater 

invertebrates 

Acute 

TGAI 

(97.7%) 

Water Flea 

(Daphnia magna) 

48-hr EC50 >107 

(Practically non-toxic) 

45012808 

Acceptable 

Metabolite 

7017 (99.8%) 

48-hr EC50 >106 

(Practically non-toxic) 

45012826 

Acceptable 

Metabolite 

8394 (99.8%) 

48-hr EC50 >94.1 

(Slightly toxic to Practically 

non-toxic) 

45012829 

Acceptable 

Chronic TGAI 

(97.3%) Water Flea 

21-d NOAEC = 106 

21-d LOAEC >106 

No effects observed 

45012802 

Acceptable 

Estuarine/ 

marine 

invertebrates 

Acute 

(Shell 

Deposition) 

TGAI 

(95.4%) 

Eastern Oyster 

(Crassostrea 

virginica) 

96-hr EC50 >130 

(Practically non-toxic) 

45012805 

Acceptable 

Acute TGAI 

(95.4%) 

Mysid Shrimp 

(Mysidopsis bahia) 

96-hr LC50 >146 

(Practically non-toxic) 

45012804 

Acceptable 
-Page 30 of 66- 

Taxonomic 

Group 

Study 

Type 

Test 

Substance 

(% a.i.) 

Surrogate Species 

Toxicity Value 

measured mg a.i./L 

(Acute Toxicity Category) 

MRID and 

Study 

Classification 

Chronic TGAI 

(95.4%) Mysid Shrimp 

27-d NOAEC = 123 

27-d LOAEC >123 

No effects observed 

45012801 

Supplemental 

3.3.1.2. Toxicity to Aquatic Plants

A summary of data on toxicity to aquatic plants for technical grade propoxycarbazone-sodium, 

formulations, and transformation products is presented in Table 3.12. The most toxic response 

observed was in the study of parent propoxycarbazone-sodium toxicity to the vascular aquatic 

plant duckweed. The next most sensitive species tested was green algae, which was two orders of 

magnitude less sensitive than duckweed. The propoxycarbazone-sodium degradates tested were 

less toxic than the parent to both duckweed and green algae. The parent compound exhibited 

slight toxicity to blue-green algae and no toxicity at the concentrations tested to freshwater or 

marine diatoms.

Table 3.12. Summary of Available Toxicity Data for Vascular and Nonvascular Aquatic Plants Exposed to 

Propoxycarbazone-sodium and its Degradates 

Taxonomic 

Group 

Study 

Type 

Test 

Substance 

(% a.i.) 

Surrogate Species 

Toxicity Value 

measured mg a.i./L 

(Most Sensitive Endpoint) 

MRID and 

Study 

Classification 

Aquatic 

plants and 

algae 

Vascular 

TGAI 

(97.3%) 

Duckweed 

(Lemna gibba) 

14-d NOAEC = 0.0031 

14-d EC50 = 0.0064 

(Biomass) 

45012815 

Supplemental 

Metabolite 

7017 

(100.3%) 

7-d NOAEC = 103 

7-d EC50 > 103 

(Frond area) 

45012830 

Supplemental 

Metabolite 

8394 (99.8%) 

7-d NOAEC = 0.40 

7-d EC50 = 12 

(Frond area) 

45012822 

Acceptable 

Nonvascular 

TGAI 

(97.3%) 

Green Algae 

(Pseudokirchneriella 

subcapitata) 

96-hr NOAEC = 0.53 

96-hr EC50 = 1.57 

(Biomass) 

45012814 

Acceptable 

Formulation 

(70.7%) 

72-hr NOAEC = 0.612 

72-hr EC50 = 4.8 

(Cell density) 

45012831 

Supplemental 

Metabolite 

7017 

(100.3%) 

96-hr NOAEC = 99.5 

96-hr EC50 >99.5 

(Biomass) 

45012833 

Acceptable 

Metabolite 

8394 (99.8%) 

72-hr NOAEC <87.8 

72-hr EC50 >87.8 

(Cell density) 

45012834 

Acceptable 

TGAI 

(98.0%) 

Blue-green Algae 

(Anabaena flosaquae) 

96-hr NOAEC = 3.26 

96-hr EC50 = 11.3 

(Cell density) 

45012803 

Acceptable 
-Page 31 of 66- 

Taxonomic 

Group 

Study 

Type 

Test 

Substance 

(% a.i.) 

Surrogate Species 

Toxicity Value 

measured mg a.i./L 

(Most Sensitive Endpoint) 

MRID and 

Study 

Classification 

TGAI 

(97.7%) 

Freshwater Diatom 

(Navicula 

pelliculosa) 

96-hr NOAEC = 111 

96-hr EC50 > 111 

(Cell density) 

45012807 

Acceptable 

TGAI 

(97.3%) 

Marine Diatom 

(Skeletonema 

costatum) 

96-hr NOAEC = 134 

96-hr EC50 > 134 

(No effects observed) 

45012812 

Acceptable 

3.3.1.3. Degradate Toxicity 

No toxic effects were observed in acute studies of propoxycarbazone-sodium parent or 

degradates MKH 7017 and MKH 8394 on freshwater fish up to the limit concentration of 100 

mg a.i./L. The degradates tested may therefore be more, less, or equally toxic as the parent 

compound. However, they are not included as stressors of concern due to the lack of observable 

adverse effects at the limit concentration. 

For freshwater invertebrates, no toxicity was observed in acute studies with the parent compound 

up to the limit concentration, but slight toxicity (10% immobilization observed at the top 

concentration) was observed for both degradates tested, MKH 7017 and MKH 8394. This 

indicates that the triazolinone degradates may be more toxic than the parent to freshwater 

invertebrates. However, the acute toxicity endpoints for the degradates were still greater than the 

limit concentration and therefore the degradates are not considered stressors of concern. 

In toxicity studies on vascular and non-vascular aquatic plants the propoxycarbazone-sodium 

degradates MKH 7017 and MKH 8394 were at least two orders of magnitude less toxic than the 

parent compound. Therefore, these degradates are not included as stressors of concern for 

aquatic plants. 

See Section 3.2.1.3 for additional discussion of the propoxycarbazone-sodium degradates. 

3.3.2. Terrestrial Effects Characterization 

3.3.2.1. Toxicity to Terrestrial Animals 

A summary of data on toxicity to birds, mammals, and terrestrial invertebrates for technical 

grade propoxycarbazone-sodium, formulations, and transformation products is presented in 

Table 3.13. 

In the avian acute oral and sub-acute dietary studies, the only adverse effects observed were in 

the acute oral study with the canary. The canary exhibited clinical signs of toxicity and transient 

effects to body weight change at the limit dose, but all birds fully recovered by day 2 of the study 

and the limit dose was determined to be greater than 10 times the highest avian EEC. In the avian 

reproduction studies, statistically significant effects on reproductive endpoints were observed for 

both the bobwhite quail and mallard duck at the highest treatment concentrations. 
-Page 32 of 66- 

No mortality or clinical signs of toxicity were observed in acute oral or acute inhalation studies 

with the rat. The 2-generation reproduction study with the rat showed effects on reproduction 

and offspring, including post implantation loss and decreased litter size. 

Acute contact honey bee studies with the TGAI and a formulation showed no effects up to the 

limit dose. Acute oral honey bee studies with the TGAI showed some clinical signs of toxicity 

after 4 hours of exposure, but no significant effects on mortality. These effects were not seen in 

the acute oral honey bee study with the formulation. Additional toxicity data for honey bees will 

allow for a more thorough hazard assessment (see Section 8). No effects were observed in 

studies on earthworms including acute and chronic studies with the TGAI, degradates, and 

formulations. 

Table 3.13. Summary of Available Toxicity Data for Terrestrial Animals Exposed to Propoxycarbazonesodium 

Taxonomic 

Group Study Type Test Substance Surrogate Species 

Toxicity Value 

measured a.i. 

(Acute Toxicity Category) 

MRID and 

Study 

Classification 

Birds 

Acute Oral 

TGAI 

(97.7%) 

Bobwhite quail 

(Colinus virginianus) 

LD50 >2,000 mg/kg-bw 

(Practically non-toxic) 

45012813 

Acceptable 

TGAI 

(97.7%) 

Canary (Serinus 

canaria) 

LD50 >2,000 mg/kg-bw 

(Practically non-toxic) 

49072701 

Acceptable 

Sub-acute 

dietary 

TGAI 

(97.7%) Bobwhite quail LC50 >10,566 mg/kg-diet 

(Practically non-toxic) 

45012816 

Acceptable 

TGAI 

(99.9%) 

Mallard duck (Anas 

platyrhynchus) 

LC50 >10,339 mg/kg-diet 

(Practically non-toxic) 

45012821 

Acceptable 

Chronic 

TGAI 

(97.7%) Bobwhite quail 

NOAEC = 324 mg/kg-diet 

LOAEC = 999 mg/kg-diet 

Decreased eggs laid/pen 

49072702 

Acceptable 

TGAI 

(96.3%) Mallard duck 

NOAEC = 268 mg/kg-diet 

LOAEC = 1260 mg/kg-diet 

Decreased viable embryos, 

hatchlings, & survivors/eggs 

set, and eggshell thickness 

45012832 

Acceptable 

Mammals1

Acute Oral TGAI 

(97.8%) 

Laboratory rat 

(Rattus norvegicus) 

LD50 >5,000 mg/kg-bw 

(Practically non-toxic) 

45012509 

Acceptable 

Acute 

Inhalation 

TGAI 

(97.8%)

LC50 > 5.03 mg/L 

(Toxicity Category IV - Low) 

45012505 

Acceptable 

Chronic (2-

generation 

reproduction) 

TGAI 

(97.6%) 

NOAEC=297 mg/kg-bw/day 

LOAEC=1231 mg/kg-bw/day 

Increased post-implantation 

loss; Decreased F2 litter size 

45012529 

Acceptable 

Insects 

Acute 

contact 

TGAI 

(96.9%) 

Honey bee 

(Apis mellifera) 

48-hr LD50 >200 μg/bee 

(Practically non-toxic) 

45012818 

Acceptable 

Formulation 

(70.7%) 

48-hr LD50 >200 μg/bee 

(Practically non-toxic) 

45012838 

Acceptable 

Acute oral TGAI 

(96.9%) 

48-hr LD50 >319 μg/bee 

(Practically non-toxic) 

45012818 

Supplemental 
-Page 33 of 66- 

Taxonomic 

Group Study Type Test Substance Surrogate Species 

Toxicity Value 

measured a.i. 

(Acute Toxicity Category) 

MRID and 

Study 

Classification 

Formulation 

(70.7%) 

48-hr LD50 >402 μg/bee 

(Practically non-toxic) 

45012838 

Supplemental 

Soil 

invertebrates 

Acute 

TGAI 

(96.6%) 

Earthworm (Eisenia 

fetida) 

LC50 > 1,000 mg/kg-diet 45012825 

Supplemental 

Metabolite 

7284 (99.4%) LC50 > 1,000 mg/kg-diet 45012835 

Supplemental 

Metabolite 

STJ 4934 

(99.9%) 

LC50 > 1,000 mg/kg-diet 45012836 

Supplemental 

Chronic Formulation 

(70.7%) 

NOAEC = 0.31 lb/A 

LOAEC >0.31 lb/A 

No effects observed 

45012837 

Supplemental 

1

 Mammalian toxicity endpoints for propoxycarbazone-sodium provided and reviewed by the U.S. EPA Office of 

Pesticide Programs Health Effects Division (HED).

3.3.2.4. Toxicity to Terrestrial Plants 

A summary of data on toxicity to terrestrial plants for a propoxycarbazone-sodium formulation is 

presented in Table 3.14. Consistent with the herbicidal mode of action, terrestrial plants are 

sensitive to propoxycarbazone-sodium exposure. The most sensitive monocot was onion and the 

most sensitive dicot was canola in both the seedling emergence and vegetative vigor studies. 

Table 3.14. Summary of Available Toxicity Data for Terrestrial Plants Exposed to Propoxycarbazonesodium 70WG Formulation 

Type of 

Study 

Species 

Crop IC25

(lbs a.i./A) 

NOAEC 

or IC05

(lbs a.i./A) 

Most Sensitive 

Endpoint 

MRID and 

Study 

Classification 

Seedling Emergence 

Monocots 

Corn 0.0070 0.0067 Dry weight 

45012823 

Acceptable 

Rye 0.0014 0.00084 Dry weight 

Oat 0.0088 0.0067 Shoot height 

Onion 0.00045 0.000034 Dry weight 

Dicots 

Flax >0.013 0.013 None 

Soybean >0.013 0.013 None 

Sunflower 0.012 0.0060 Dry weight 

Sugar beet 0.0020 0.0017 Dry weight 

Canola 0.00058 0.00021 Dry weight 

Buckwheat 0.012 0.0035 Dry weight 

Vegetative Vigor 

Monocots 

Corn 0.0017 0.00070 Dry weight 

45012823 

Acceptable 

Rye 0.0029 0.00052 Dry weight 

Oat 0.00098 0.00031 Dry weight 

Onion 0.00065 0.000063 Dry weight 

Dicots 

Flax 0.0055 0.0017 Shoot height 

Soybean 0.0037 0.00084 Shoot height 

Sunflower 0.0025 0.00084 Shoot height 

Sugar beet 0.00089 0.00084 Dry weight 

Canola 0.00049 0.00021 Shoot height 

Buckwheat 0.0012 0.00039 Shoot height 
-Page 34 of 66- 

Bolded values are the most sensitive endpoints that are used for risk estimation (i.e., RQ calculations) 

3.3.3. Review of Incident Data 

The Ecological Incident Information System (EIIS), which is maintained by the Agency’s Office 

of Pesticide Programs, was searched to determine if ecological incidents have been reported for 

propoxycarbazone-sodium. Based on a search of EIIS conducted in November 2014, the Agency 

has received 30 reports of adverse field effects to non-target plants that have been linked to the 

use of propoxycarbazone-sodium. All of these incidents involved damage to spring or winter 

wheat. In 27 incidents, the damaged crop was treated directly with a propoxycarbazone-sodium 

product. One incident was attributed to drift or runoff from an adjacent field and two did not 

report the route of exposure. The Agency considered the likelihood that propoxycarbazonesodium was the cause of the incidents as unlikely in one case, possible in 21 cases, and probable 

in eight cases. 

The American Bird Conservancy Avian Incident Monitoring System was searched in November 

2014 and returned no records of incidents associated with propoxycarbazone-sodium10. 

Based on a search of the U.S. EPA Office of Pesticide Programs Incident Data System (IDS), 

which compiles aggregate incidents, there were a total of 36 incidents involving 

propoxycarbazone-sodium between 2005 and 2013, all of which were associated with minor 

plant damage. 

A lack of reported incidents does not necessarily mean that such incidents have not occurred. In 

addition, incident reports for non-target plants and animals typically provide information on 

acute mortality events only. Reports for other adverse effects, such as reduced growth or 

impaired reproduction, are rarely received. 

4. Risk Characterization 

4.1. Risk Estimation 

 

This screening-level assessment of the labeled uses of propoxycarbazone-sodium relies on the 

deterministic RQ method to provide a metric of potential risks. The RQ provides a comparison of 

exposure estimates to toxicity endpoints (i.e., the estimated exposure concentrations are divided 

by acute and chronic toxicity values, respectively). The resulting unitless RQ values are 

compared to the Agency’s LOCs. The LOCs, when exceeded, are used by the Agency to indicate 

when the use of a pesticide, as directed by the label, has the potential to cause adverse effects of 

concern to non-target organisms. For endangered species, LOC exceedances require an 

additional in-depth evaluation of the potential co-occurrence of listed species and areas in which 

crops are grown to characterize risks. 

 

 

10 http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm 
-Page 35 of 66- 

4.1.1. Aquatic Organisms 

4.1.1.1. Fish, Amphibians, and Invertebrates 

RQ values are not calculated for acute risk to freshwater or estuarine/marine fish or invertebrates 

because the available toxicity endpoints for all tested species are non-definitive. Even if these 

non-definitive endpoints were conservatively equated to an EC50 or LC50 the RQs would be less 

than the LOC of 0.05 for listed aquatic species for all species tested. The potential for risk to 

fish, amphibians, and aquatic invertebrates is further discussed in the Risk Description (Section 

4.2). 

Chronic RQ values for freshwater and estuarine/marine fish and invertebrates are <0.01 across 

all labeled uses of propoxycarbazone-sodium and therefore do not exceed the chronic risk LOC 

(LOC = 1) for aquatic animals. Throughout this screening-level assessment, conclusions for 

freshwater fish are assumed to apply to aquatic-phase amphibians. 

4.1.1.3. Aquatic Plants 

Table 4.1 presents RQ values calculated for aquatic plants exposed to propoxycarbazone-sodium 

residues in surface water based on the most sensitive toxicity data for the TGAI. The RQs do not 

exceed the LOC (LOC = 1) for listed or non-listed aquatic vascular or non-vascular plants for 

any registered uses. The SWCC modeling scenarios that resulted in the highest EECs for each 

use (Table 3.7) are used for the RQ calculations. 

Table 4.1. RQ Values for Aquatic Plants from Exposure to Propoxycarbazone-sodium TGAI 

Taxonomic 

Group 

Listed 

Status 

Toxicity 

Endpoint 

(mg a.i./L) 

RQ Values for Labeled Uses1

Triticale, Wheat 

(EEC = 2.29 μg/L) 

Agricultural 

Fallow/CRP Land 

(EEC = 1.08 μg/L) 

Pasture, 

Rangeland 

(EEC = 1.03 μg/L) 

Vascular 

aquatic plants 

Non-listed EC50 = 0.0064 0.36 0.17 0.16 

Listed NOAEC = 0.0031 0.74 0.35 0.33 

Non-vascular 

aquatic plants 

Non-listed EC50 = 1.57 0.0015 0.0007 0.0007 

Listed NOAEC = 0.53 0.0043 0.0020 0.0019 1

 RQ=EEC/toxicity endpoint. 

4.1.2. Terrestrial Organisms 

4.1.2.1. Birds and Mammals 

RQ values are not calculated for acute risk to birds on a dose or dietary exposure basis because 

the available toxicity endpoints for bobwhite quail, mallard duck, and canary are non-definitive. 

Similarly, RQ values are not calculated for acute risk to mammals because the available toxicity 

endpoint for the laboratory rat is non-definitive. Even if these non-definitive endpoints were 

conservatively equated to an LD50 or LC50 the RQs would be less than the LOC of 0.1 for listed 

birds and mammals for all species tested (see sample T-REX output in Appendix B). The 

potential for risk to birds (and therefore to terrestrial-phase amphibians and reptiles) and 
-Page 36 of 66- 

mammals is further discussed in the Risk Description (Section 4.2). 

Chronic RQ values for birds based upon a NOAEC of 268 mg a.i./kg-diet for the mallard duck 

range from <0.01 to 0.05 across labeled uses of propoxycarbazone-sodium and therefore do not 

exceed the chronic risk LOC (LOC = 1) for birds. Throughout this screening-level assessment, 

conclusions for birds are assumed to apply to terrestrial-phase amphibians and reptiles. 

Chronic RQ values for mammals based on a NOAEC of 297.1 mg a.i./kg-bw/day for the 

laboratory rat range from <0.01 to 0.02 across labeled uses of propoxycarbazone-sodium and 

therefore do not exceed the chronic risk LOC (LOC = 1) for mammals. 

4.1.2.2. Terrestrial Invertebrates 

The acute contact and oral toxicity endpoints for honey bees, which are used to evaluate risk to 

terrestrial invertebrates, are non-definitive. Therefore, RQ values are not calculated for acute risk 

to terrestrial invertebrates. However, even if the EECs are compared to the highest 

concentrations tested for the honey bee acute contact and oral studies, the RQs would be almost 

100 times lower than the acute risk LOC of 0.4 for bees (USEPA et al., 2014). No toxicity data 

are available for calculation of chronic RQs for adult bees or for acute or chronic RQs for bee 

larvae. Further analysis will be conducted following receipt of these additional data (see Section 

8 for details). 

4.1.2.3. Terrestrial Plants 

The RQs for listed and non-listed terrestrial plants, including monocots and dicots, exceed the 

LOC (LOC = 1) for almost all exposure scenarios modeled in TERRPLANT (see Table 4.2). 

The only exception is for non-listed plants exposed to spray drift only for ground applications to 

triticale and wheat. However, updated spray drift data demonstrates that the default spray drift 

assumptions in TERRPLANT are lower than would be expected (USEPA, 2013). With the 

revised spray drift fraction of 6% for ground applications, the RQs would exceed the LOC for all 

scenarios. 

Table 4.2. RQs for Terrestrial Plants Inhabiting Dry and Semi-Aquatic Areas Exposed to Propoxycarbazonesodium via Runoff and Drift 

Type of Plant 

Ground spray Aerial Spray 

Dry Areas 

SemiAquatic 

Areas 

Spray Drift 

Only Dry Areas 

SemiAquatic 

Areas 

Spray Drift 

Only 

Agricultural Fallow/Conservation Reserve, Pastures, Rangeland 0.0525 lb a.i./A 

Monocot 

Nonlisted 7.0 60 1.2 12 64 5.8 

Listed 93 788 15 154 849 77 

Dicot 

Nonlisted 5.4 46 1.1 9.1 50 5.4 

Listed 15 128 2.5 25 138 13 

Triticale and Wheat 0.0395 lb a.i./A 

Monocot Non- 5.3 45 0.88 8.8 48 4.4 
-Page 37 of 66- 

listed 

Listed 70 593 12 116 639 58 

Dicot 

Nonlisted 4.2 35 0.81 6.8 38 4.0 

Listed 11 96 1.9 19 103 9.4 

Bolded RQ values exceed the level of concern for risk to plants (LOC = 1). 

4.2. Risk Description 

4.2.1. Risks to Aquatic Organisms 

4.2.1.1. Fish, Aquatic-phase Amphibians, and Invertebrates 

Propoxycarbazone-sodium exhibited no toxicity to any of the fish or aquatic invertebrate species 

studied at tested concentrations. No RQs exceeded the LOCs for listed or non-listed aquatic 

species and no incidents associated with propoxycarbazone-sodium involving aquatic species 

have been reported to the Agency. While acute RQs could not be calculated due to non-definitive 

toxicity endpoints, even if these non-definitive endpoints were conservatively equated to an EC50

or LC50 the RQs would be less than the LOC of 0.05 for listed aquatic species for all species 

tested. Freshwater fish are assumed to represent aquatic-phase amphibians in this assessment. 

While propoxycarbazone-sodium is a highly soluble, mobile, and persistent compound, the low 

toxicity and low application rates result in no acute or chronic risks of concern for aquatic 

species. 

There is some uncertainty in the assessment of risk to aquatic species due to the lack of chronic 

toxicity data for estuarine/marine fish and the lack of toxicity data for benthic invertebrates. 

However, due to the consistent lack of observable adverse effects across all species for which 

data are available, these additional data are not expected to change the conclusions. An acute-tochronic ratio cannot be calculated to estimate chronic risk to estuarine/marine fish due to the 

non-definitive acute toxicity endpoints. Additionally, propoxycarbazone-sodium is not expected 

to partition to sediment due to its low Kow value. 

4.2.1.2. Aquatic Plants 

Propoxycarbazone-sodium is very highly toxic to vascular aquatic plants and at most moderately 

toxic to the tested species of non-vascular aquatic plants. However, RQs do not exceed the LOC 

(LOC = 1) for listed or non-listed aquatic vascular or non-vascular plants for any registered uses. 

The highest RQ is 0.74 for listed vascular aquatic plants exposed to propoxycarbazone-sodium 

following use on winter and spring wheat. 

This conclusion for listed vascular aquatic plants differs from the last risk assessment conducted 

for use of propoxycarbazone-sodium on pasture and rangeland (USEPA, 2008). In that 

assessment, the EC05 value of 0.002 μg a.i./L was used to assess risk to listed vascular aquatic 

plants. However, the toxicity study on duckweed (MRID 45012815) also provides a NOAEC of 

0.0031 μg a.i./L. Therefore, the NOAEC is used for RQ calculation in this assessment. 
-Page 38 of 66- 

4.2.2. Terrestrial Organisms 

4.2.2.1. Birds, Reptiles, and Terrestrial-phase Amphibians 

Propoxycarbazone-sodium is practically non-toxic on an acute basis to all avian species tested. 

No toxic effects were observed in acute and sub-acute studies with the bobwhite quail or mallard 

duck. The canary exhibited clinical signs of toxicity and transient effects on body weight change 

at the limit dose, but all birds fully recovered by day 2 of the study and the limit dose was greater 

than 10 times the highest avian EEC. Acute RQ values are not calculated for avian species due to 

the non-definitive toxicity endpoints. However, even if these non-definitive endpoints were 

conservatively equated to an LD50 or LC50 the RQs would be less than the LOC of 0.1 for listed 

birds for all species tested (see sample T-REX output in Appendix B). The STIR model 

indicates that inhalation of vapor and spray drift is not an exposure route of concern for birds 

(see Appendix D). The SIP model indicates that drinking water exposure may be a potential 

pathway of concern for wildlife due to the high solubility of propoxycarbazone-sodium (42,000 

mg/L); however, risks are unlikely due to the non-definitive toxicity endpoints for both birds and 

mammals and low application rates (see Appendix E). Throughout this screening-level 

assessment, conclusions for birds are assumed to apply to terrestrial-phase amphibians and 

reptiles. 

In the avian reproduction studies, statistically significant effects on reproductive endpoints were 

observed for both the bobwhite quail and mallard duck at the highest treatment concentrations. 

Chronic RQ values calculated using these endpoints do not exceed the chronic risk LOC of 1 for 

listed and non-listed birds. 

No incidents associated with propoxycarbazone-sodium involving avian species have been 

reported to the Agency. 

4.2.2.2. Mammals 

No mortality or clinical signs of toxicity were observed in acute oral study with the rat. Acute 

RQ values are not calculated for mammals due to the non-definitive toxicity endpoint. However, 

even if this non-definitive endpoint was conservatively equated to an LD50 the RQs would be 

less than the LOC of 0.1 for listed mammals (see sample T-REX output in Appendix B). 

Additionally, no mortality or clinical signs of toxicity were observed in the acute inhalation 

study with the rat, and the STIR model indicates that inhalation of vapor and spray drift is not an 

exposure route of concern for mammals (see Appendix D).

The 2-generation reproduction study with the rat showed effects on reproduction and offspring, 

including post implantation loss and decreased litter size. Chronic RQ values based on these 

endpoints do not exceed the chronic risk LOC of 1 for listed and non-listed mammals. 

No incidents associated with propoxycarbazone-sodium involving mammals have been reported 

to the Agency. 
-Page 39 of 66- 

4.2.2.3. Terrestrial Invertebrates 

Acute contact honey bee studies with the TGAI and a formulation showed no effects up to the 

limit dose. Acute oral honey bee studies with the TGAI showed some clinical signs of toxicity 

after 4 hours of exposure, but no significant effects on mortality. These effects were not seen in 

the acute oral honey bee study with the formulation. Because the endpoints from these studies 

are non-definitive, RQ values are not calculated for acute risk to terrestrial invertebrates. 

However, even if the EECs for honey bees are compared to the highest concentrations tested in 

the submitted honey bee acute contact and oral studies, the RQs would not exceed the acute risk 

LOC of 0.4 for bees (USEPA et al., 2014). 

There is uncertainty regarding the potential acute and chronic effects of the compound on honey 

bee larvae as well as potential for chronic effects on adult bees. Since propoxycarbazone-sodium 

is a systemic herbicide, residues may be present in pollen and/or nectar and represent a route of 

exposure for bees through both contact and ingestion. Therefore, there is uncertainty with respect 

to the likelihood of adverse effects from acute or chronic exposure of larval bees to residues that 

may be translocated to pollen or nectar. While wheat and triticale are not pollinator-attractive 

crops, spray drift and runoff from these uses may result in propoxycarbazone-sodium exposure to 

non-target blooming plants. Additionally, pollinator attractive crops may be present on pasture, 

rangeland, and Conservation Reserve Program land treated with propoxycarbazone-sodium. 

Therefore, additional data on pollinators is needed to fully characterize the risk associated with 

propoxycarbazone-sodium use to all developmental stages of honey bees, as sensitivity may vary 

according to life-stage and length of exposure (adult vs. larval and acute vs. chronic, 

respectively). These data are required under the Guidance for Assessing Pesticide Risks to Bees 

(USEPA et al., 2014). See Section 8 for additional details. 

No effects were observed in studies on earthworms including acute and chronic studies with the 

TGAI, degradates, and formulations. 

No incidents associated with propoxycarbazone-sodium involving terrestrial invertebrates, such 

as bee kills, have been reported to the Agency. 

4.2.2.4. Terrestrial Plants 

Consistent with the herbicidal mode of action, propoxycarbazone-sodium exhibits toxicity to 

terrestrial plant species. Both monocots and dicots were affected by propoxycarbazone-sodium in 

the seedling emergence and vegetative vigor studies. The RQs for listed and non-listed terrestrial 

plants, including monocots and dicots, exceed the LOC of 1 for almost all modeled exposure 

scenarios, including aerial and ground applications for all registered uses. The only exception is 

for non-listed plants exposed to spray drift only for ground applications to triticale and wheat. 

However, updated spray drift data demonstrates that the default spray drift assumptions in 

TERRPLANT are lower than would be expected (USEPA, 2013). With the revised spray drift 

fraction of 6% for ground applications, the RQs would exceed the LOC for all scenarios. 
-Page 40 of 66- 

The Agency has received 30 individual reports of adverse field effects to non-target plants that 

have been linked to the use of propoxycarbazone-sodium and an additional 36 aggregated reports 

of minor plant damage. All of the 30 incidents with detailed reports involved damage to spring or 

winter wheat. The damaged crop was treated directly with propoxycarbazone-sodium in the 

majority of the incidents, however one incident was attributed to drift or runoff from an adjacent 

field. 

Spray Drift 

Non-target terrestrial plant species could be impacted by exposure to propoxycarbazone-sodium 

via spray drift in areas adjacent to treated fields. The distances from the treated fields at which 

non-target plants may be affected due to spray drift are calculated using AgDRIFT v2.1.1 and are 

presented in Table 4.3 below. AgDRIFT input parameters were selected using EFED’s Guidance 

on Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and Drinking Water 

Assessments (USEPA, 2013). High boom height (50 in or 4.2 ft) for ground applications is 

consistent with the labeled height restriction of 4 ft above the crop canopy. Labels for all end-use 

products with the exception of Olympus® 70% WDG specify medium droplet sizes. The 

Olympus® 70% WDG label specifies a coarse droplet size. Therefore, the fine to medium/coarse 

drop size distribution (DSD) was modeled for ground applications, and both the fine to medium 

DSD and the medium to coarse DSD categories were modeled for aerial applications. 

A spray drift buffer for aerial applications would need to be >1,000 ft to reduce risks to listed 

plants below levels of concern for all registered uses. For ground applications, spray drift buffer 

distances for listed plants range from 150 to 200 ft for dicots and 530 to 700 ft for monocots. For 

non-listed plants, buffer distances are reduced (see Table 4.3). The most sensitive endpoints 

from the vegetative vigor study were used for these calculations (monocot: onion NOAEC = 

0.000063 lb a.i./A, IC25 = 0.00065 lb a.i./A; dicot: canola NOAEC = 0.00021 lb a.i./A, IC25 = 

0.00049 lb a.i./A). 

Table 4.3. Possible Effects Distance for Nontarget Terrestrial Plants Exposed to Propoxycarbazone-sodium 

through Spray Drift Only Based on the Most Sensitive Crop Species 

Type of Plant 

Buffer Distance for Ground 

Spray1 (ft) Buffer Distance for Aerial Spray2

 (ft) 

Fine to Medium/Coarse DSD Fine to Medium DSD Medium to Coarse DSD 

Agricultural Fallow/Conservation Reserve, Pastures, Rangeland 0.0525 lb a.e./A 

Monocot Non-listed 50 900 350 

Listed 700 >1,000 >1,000 

Dicot Non-listed 70 >1,000 450 

Listed 200 >1,000 >1,000 

Triticale and Wheat 0.0395 lb a.i./A 

Monocot Non-listed 40 580 275 

Listed 530 >1,000 >1,000 

Dicot Non-listed 50 900 350 

Listed 150 >1,000 >1,000 1

 Ground buffer distances are calculated using high boom height (50 in) and ASAE Fine to Medium/Coarse Drop 

Size Distribution (DSD). Default AgDRIFT Tier I parameters are used for all other settings. 2

 Aerial buffer distances are calculated using both ASAE Fine to Medium DSD and Medium to Coarse DSD. 

Default AgDRIFT Tier I parameters are used for all other settings. 
-Page 41 of 66- 

Four of the five currently registered end-use products (all products except for OlympusTM

Rangeland Herbicide) include the following label language regarding buffers: 

To avoid adverse effects on endangered plant species, the following mitigation measures 

will be required where endangered species occur in Counties listed in the table on the 

following page. 

For ground applications, the applicator must: 

1. Apply when there is sustained wind away from native plant communities, OR 

2. Leave 50 foot untreated buffer between treatment area and native plant communities. 

For aerial applications, the applicator must: 

1. Apply only when there is sustained wind away from native plant communities, OR 

2. Leave 350 foot untreated buffer between treatment area and native plants 

Specific counties are listed following this language on three of the four labels. The buffer 

distances of 50 ft for ground applications and 350 ft for aerial applications are smaller than those 

calculated for the protection of listed, and in most cases non-listed, terrestrial plants (Table 4.3). 

Irrigation Water 

The use of surface and/or groundwater-derived irrigation water containing propoxycarbazonesodium may result in damage to the irrigated crops due to the compound’s high mobility and 

potential to persist in aquatic environments. The following equation can be used to estimate 

exposure to terrestrial plants when one inch of surface or ground water contaminated with 

propoxycarbazone-sodium is applied to crops for irrigation. Z mg/L is the concentration in the 

irrigation water. 

EEC lb a.i./Acre = (Z mg/L) * (102,790 L water/ Acre-in) * (1 inch) * (1 lb/ 453,592 mg) 

Similarly the depth of water applied to a field that would lead to a potential risk concern can be 

calculated using the following equation: 

X inches = [(EEC or IC25 in lbs a.i./Acre) *(Acre-in /102,790 L water) * (453,592 mg/ 1lb)] / 

(Z mg/L) 

The post breakthrough mean groundwater concentration modeled in the drinking water 

assessment conducted for Registration Review was 2.8 ppb (PRZM-GW, USEPA, 2014c). 

Comparing this concentration to the most sensitive terrestrial plant endpoint (seedling emergence 

canola NOAEC = 0.000034 lb a.i./A, IC25 = 0.00045 lb a.i./A), 1/20 of an inch of irrigation 

would be required to cause a risk concern for listed species, and 3/4 of an inch of irrigation 

would be required to cause a risk concern for non-listed species. If propoxycarbazone-sodium 

degrades more quickly below the 1-meter depth than PRZM-GW allows or if it laterally 

disperses in subsurface soils, the concentrations in irrigation water may be lower and the amount 

of irrigation water required to cause a risk concern may therefore be higher. 
-Page 42 of 66- 

The same equations can be used to estimate the concentration of propoxycarbazone-sodium in 

water used for irrigation that would trigger a risk concern for terrestrial plants. Using the most 

sensitive terrestrial plant endpoints and assuming application of one inch of irrigation water, the 

concentrations are 0.15 ppb and 2.0 ppb for listed and non-listed plants, respectively. As the 

highest peak surface water EEC is 2.29 ppb, risks to terrestrial plants from use of less than 1 inch 

of surface water contaminated with propoxycarbazone-sodium for irrigation purposes could also 

result in risks of concern for listed and non-listed terrestrial plants. 

5. Listed Species of Concern 

5.1. Evaluating Risks to Listed Species 

Consistent with EPA’s responsibility under ESA, the Agency will evaluate risks to federally 

listed threatened and endangered (listed) species from registered uses of pesticides in accordance 

with the Joint Interim Approaches developed to implement the recommendations of the April 

2013 National Academy of Sciences (NAS) report.11 The NAS report outlines recommendations 

on specific scientific and technical issues related to the development of pesticide risk 

assessments that EPA and the U.S. Fish and Wildlife Service and National Marine Fisheries 

Service (collectively, the Services) must conduct in connection with their obligations under the 

ESA and FIFRA. EPA will address concerns specific to propoxycarbazone-sodium in connection 

with the development of its final Registration Review decision for propoxycarbazone-sodium. 

In November 2013, EPA, the Services, and the U.S. Department of Agriculture (USDA), 

released a white paper12 containing a summary of their joint Interim Approaches for assessing 

risks to listed species from pesticides. These Interim Approaches were developed jointly by the 

agencies in response to the NAS recommendations, and reflect a common approach to risk 

assessment shared by the agencies as a way of addressing scientific differences between the EPA 

and the Services. Details of the joint Interim Approaches are contained in the November 1, 2013 

white paper. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, this preliminary Registration Review risk assessment for 

propoxycarbazone-sodium does not describe the specific ESA analysis, including effects 

determinations for specific listed species or designated critical habitat. Rather, a screening level 

assessment is provided below. This will allow EPA to focus its future evaluations on the types of 

species where the potential for effects exists, once the scientific methods being developed by the 

agencies have been fully vetted. Once the agencies have fully developed and implemented the 

scientific methods necessary to complete risk assessments for listed species and their designated 

 

11 Assessing Risks to Endangered and Threatened Species from Pesticides. Available at: 

http://www.nap.edu/catalog.php?record_id=18344

12 Interim Approaches for National-Level Pesticide Endangered Species Act Assessments Based on the 

Recommendations of the National Academy of Sciences April 2013 Report. Available at:

http://www.epa.gov/espp/2013/nas.html
-Page 43 of 66- 

critical habitats, these methods will be applied to subsequent analyses of propoxycarbazonesodium as part of completing this Registration Review. 

5.2. Taxonomic Groups Potentially at Risk 

Based on this screening-level assessment, there are potential risks of direct effects to listed and 

non-listed terrestrial plants from the use of propoxycarbazone-sodium on all of its registered use 

sites. Listed species of all taxa may also be affected through indirect effects because of the 

potential direct effects on listed and non-listed terrestrial plants. Potential direct effects on listed 

and non-listed terrestrial plants from the use of propoxycarbazone-sodium may be associated 

with modification of primary constituent elements of designated critical habitats, where such 

designations have been made. These conclusions are summarized in Table 5.1. 

Table 5.1. Potential Effects to Federally-Listed Taxa Associated with Direct or Indirect Effects from the 

Labeled Uses of Propoxycarbazone-sodium 

Listed Taxon Direct Effects Indirect Effects Uses of Concern 

Terrestrial and semi-aquatic 

plants - monocots Yes Yes

Agricultural fallow/ 

Conservation reserve, Pasture, 

Rangeland, Triticale, Wheat 

Terrestrial and semi-aquatic 

plants - dicots Yes Yes

Terrestrial invertebrates No Yes

Birds No Yes

Terrestrial-phase amphibians No Yes

Reptiles No Yes

Mammals No Yes

Aquatic plants No Yes

Freshwater fish No Yes

Aquatic-phase amphibians No Yes

Freshwater invertebrates No Yes

Marine/estuarine fish No Yes

Marine/estuarine invertebrates No Yes

6. Endocrine Disruptor Screening Program 

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

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

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision for propoxycarbazone-sodium, 

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), 

propoxycarbazone-sodium is subject to the endocrine screening part of the Endocrine Disruptor 

Screening Program (EDSP). 
-Page 44 of 66- 

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. A second list of chemicals 

identified for EDSP screening was published on June 14, 201313 and includes some pesticides 

scheduled for Registration Review and chemicals found in water. Neither of these lists should be 

construed as a list of known or likely endocrine disruptors. 

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.14

7. Conclusions 

 

Propoxycarbazone-sodium is a highly mobile, soluble, and persistent compound. The compound 

is not volatile, but is likely to move off of treated areas via a combination of runoff and leaching. 

Propoxycarbazone-sodium that reaches aquatic environments is likely to remain primarily in the 

water column, where dilution and degradation act to decrease concentrations over time. 

Propoxycarbazone-sodium is practically non-toxic on an acute exposure basis to all animal taxa, 

including birds, mammals, terrestrial invertebrates, fish, and aquatic invertebrates. Chronic 

toxicity effects were observed at high doses in studies of birds and mammals. Additional honey 

bee data are needed to conduct a more complete assessment of risk to terrestrial invertebrates 

(see Section 8). Propoxycarbazone-sodium is very highly toxic to vascular aquatic plants but at 

most moderately toxic to non-vascular aquatic plants. Consistent with the herbicidal mode of 

action, propoxycarbazone-sodium is toxic to terrestrial plants, both monocots and dicots. 

Terrestrial plants are the only taxa for which risks exceed levels of concern for currently 

registered propoxycarbazone-sodium uses on wheat, triticale, pasture, rangeland, and 

Conservation Reserve Program land. Direct effects on terrestrial plants could result in indirect 

effects to all other taxa due to habitat modifications (e.g., food sources, shelter, and areas to 

 

13 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals. 14 http://www.epa.gov/endo/ 
-Page 45 of 66- 

reproduce). Spray drift buffers from treated fields are >1,000 ft for listed terrestrial plants and up 

to 900 ft for non-listed terrestrial plants to decrease risks below the levels of concern. 

Additionally, there is a potential for damage to terrestrial plants if surface or groundwater 

contaminated with propoxycarbazone-sodium is used for irrigation. 

8. Data Gaps 

Additional data on pollinators is needed to fully characterize the risk associated with 

propoxycarbazone-sodium exposure to all developmental stages of honey bees, as sensitivity 

may vary according to life-stage and length of exposure (adult vs. larval and acute vs. chronic, 

respectively). These data requirements are summarized in the Guidance for Assessing Pesticide 

Risks to Bees (USEPA et al., 2014). The data gaps are summarized in Table 8.1 below, followed 

by justification tables for the non-guideline studies. 

Table 8.1. Propoxycarbazone-sodium Pollinator Toxicity Testing Data Gaps 

Test Guideline Study Type Test substance Additional Data 

Required? Justification 

850.3020 

(Tier 1) 

Honey bee adult acute 

contact toxicity TGAI No Study previously submitted and reviewed is scientifically sound. 

850.3030 

(Tier 1) 

Honey bee toxicity of 

residues on foliage TEP No Data not required because the acute contact LD50 > 11 μg a.i./bee. 

Non-Guideline 

Study (Tier 1) 1

Honey bee adult acute 

oral toxicity TGAI No Study previously submitted and reviewed is scientifically sound. 

Non-Guideline 

Study (Tier 1) 2

Honey bee larvae acute 

oral toxicity TGAI Yes No data available. 

Non-Guideline 

Study (Tier 1) 3

Honey bee adult chronic 

oral toxicity TGAI Yes No data available. 

Non-Guideline 

Study (Tier 1) 3

Honey bee larvae chronic 

oral toxicity TGAI Yes No data available. 

Non-Guideline 

Study (Tier 2) 4

Semi-field testing for 

pollinators (tunnel or 

colony feeding studies) 

TEP Yes 5 No data available. 

Non-Guideline 

Study (Tier 2) 

Field trial of residues in 

pollen and nectar TEP Yes 5 No data available. 

850.3040 

(Tier 2 or 3) 

Field testing for 

pollinators TEP Yes 5 No data available. 

TGAI = Technical Grade of the Active Ingredient; TEP = Typical End-Use Product 1 Honey bee acute oral toxicity test protocol available through OECD TG 213.15

2 Honey bee acute larval toxicity test protocol available through OECD TG 237.16 In some cases, information 

pertaining to acute toxicity to honey bee larvae may be obtained with the chronic honey bee larval test thereby 

negating the need for separate acute and chronic larval toxicity tests. 

3

 Draft test protocols are currently being finalized through the OECD. 4 Semi-field tunnel study protocol available through OECD Guidance 75.17

 

15 OECD. 1998a. OECD Guidelines for the Testing of Chemicals. Honeybees, Acute Oral Toxicity Test. 213. 

http://lysander.sourceoecd.org/vl=5988235/cl=12/nw=1/rpsv/cgi-bin/fulltextew.pl?prpsv=/ij/oecdjournals/1607310x/v1n2/s14/p1.idx 16 OECD. 2013. OECD Guidelines for Testing Chemicals. Honey bee (Apis mellifera) larval toxicity test, single exposure. http://www.oecdilibrary.org/environment/test-no-237-honey-bee-apis-mellifera-larval-toxicity-test-single-exposure_9789264203723-en 17 OECD. 2007. Series on Testing and Assessment Number 75. Guidance document on the honey bee (Apis mellifera L.) brood test under semifield conditions. Environmental Directorate Joint Meeting of the Chemicals Committee and the Working Party on Chemicals, Pesticides and 

Biotechnology. ENV/JM/MONO(2007)22. 31-Aug-2007. 
-Page 46 of 66- 

5

 Higher tier studies (Tier 2 and Tier 3) may be required pending the results and evaluation of Tier 1 studies. Higher 

tier studies may be required if the ratio of the EEC and larval or adult bee acute LD50 >0.4 or the ratio of the EEC 

and chronic NOAEC >1. Incident data and/or compelling open literature studies can also serve as rationale for 

requiring Tier 2 and Tier 3 studies. Study protocols should be submitted for review prior to conduct of these studies. 

Study Title: Pollinator Acute Oral Toxicity, Larvae 

Rationale for Requiring the Data 

Terrestrial invertebrates are likely to be impacted if exposed to pesticides in various use settings. 

Pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently 

brought back to the hive where larvae and pupae may be exposed. Therefore, potential adverse 

effects to developing bees and other insect pollinators could result from exposure to pesticide 

residues. Available toxicity studies do not address possible effects on brood (larvae and pupae) 

survival/development. Because of the potential for pollen and nectar to be contaminated with 

pesticide residues, and subsequently brought back to the hive, it is important to determine the 

acute oral toxicity of this compound to bee brood. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

terrestrial invertebrates using the honeybee as a surrogate test species. The guidance discusses 

Tier I laboratory-based acute toxicity studies of individual honeybee larvae as a critical 

component of the screening-level risk assessment process for examining potential risks from 

specific routes of exposure. The guidance can be found at: http://www2.epa.gov/pollinatorprotection/pollinator-risk-assessment-guidance. Additional guidance on larval honeybee toxicity 

test design can be found in OECD Test Guideline 237 http://www.oecdilibrary.org/environment/test-no-237-honey-bee-apis-mellifera-larval-toxicity-test-singleexposure_9789264203723-en.

Practical Utility of the Data 

How will the data be used? 

The Tier I acute oral toxicity data on honeybee larvae serve as a foundation for the screeninglevel assessment of potential risk to non-target organisms such as federally listed threatened or 

endangered and non-listed terrestrial invertebrate insects, including pollinators, and/or modify 

their designated critical habitat from acute oral exposures to pesticides. The data will be used to 

reduce uncertainties associated with the risk assessment for terrestrial invertebrates and will 

improve EPA’s understanding of the potential effects on terrestrial species and whether there is a 

differential sensitivity of larval bees relative to adult bees. If acute oral effects data for larvae are 

not available, risks to terrestrial insects from acute oral exposure will be assumed. 

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether 

continued registration of a pesticide is likely to result in unreasonable adverse effects to nontarget species or is likely to adversely affect listed threatened or endangered species and/or 

modify their designated critical habitat. Without these data, EPA may need to presume risk 

which will limit the flexibility of pesticide products to comply with FIFRA and the ESA, and 

could result in use restrictions. 

 http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2007)22&doclanguage=en 
-Page 47 of 66- 

Study Title: Pollinator Chronic Oral Toxicity, Adult 

Rationale for Requiring the Data 

Terrestrial invertebrates are likely to be impacted if exposed to pesticides in various use settings. 

Pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently 

brought back to the hive. Therefore, potential chronic effects to adult honeybees and other 

pollinators from oral exposure to some pesticides could exist. Currently available toxicity 

studies do not address possible lethal and sublethal effects of chronic oral exposure on adult 

terrestrial invertebrates and will assist in determining whether the sensitivity of adult bees differs 

from that of earlier life stages. Because of the potential for pollen and nectar to be contaminated 

with pesticide residues, and subsequently brought back to the hive, it is important to determine 

the chronic oral toxicity of this compound to adult honeybees and other pollinators.

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

invertebrates with the honeybee. The guidance discusses Tier I laboratory-based chronic oral 

toxicity studies of individual adult honeybees as a critical component of the screening-level risk 

assessment process for examining potential risks from specific routes of exposure. The guidance 

can be found at: http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 

Study design elements for the chronic 10-day oral toxicity test with honeybees are similar to the 

OECD Test Guideline 213 acute oral toxicity test http://www.oecd-ilibrary.org/environment/testno-213-honeybees-acute-oral-toxicity-test_9789264070165-en.

Practical Utility of the Data 

How will the data be used? 

The Tier I chronic oral toxicity data on adult bees serve as a foundation for the screening-level 

assessment of potential risk to non-target organisms including federally listed threatened or 

endangered species and non-listed terrestrial invertebrate insects, including pollinators, from 

chronic oral exposures to pesticides. The data will be used to reduce uncertainties associated 

with the risk assessment for terrestrial invertebrates and will improve EPA’s understanding of 

the potential direct and indirect lethal and sublethal effects on a broad range of terrestrial species, 

particularly insect pollinators and to determine whether adult toxicity differs substantially from 

other life stages evaluated in other Tier I tests. If chronic oral effects data for adults are not 

available, risks to terrestrial insects from chronic oral exposure will be assumed.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether 

continued registration of a pesticide is likely to result in unreasonable adverse effects to nontarget species or is likely to adversely affect listed threatened or endangered species and/or their 

designated critical habitat. Without these data, EPA may need to presume risk which will limit 

the flexibility of pesticide products to comply with FIFRA and the ESA, and could result in use 

restrictions. 

Study Title: Pollinator Chronic Oral Toxicity, Larvae 

Rationale for Requiring the Data 

Terrestrial invertebrates are likely to be impacted if exposed to pesticides in various use settings. 

Pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently 
-Page 48 of 66- 

brought back to the hive where larvae and pupae may be exposed. Therefore, potential effects to 

developing bees could result from chronic oral exposure to pesticide residues. Available toxicity 

studies do not address possible chronic effects on brood (larvae and pupae) survival. Because of 

the potential for pollen and nectar to be contaminated with pesticide residues, and subsequently 

brought back to the hive, it is important to determine chronic larval/pupal toxicity and whether 

adult emergence is adversely affected. This study will provide information on whether honeybee 

larvae differ in sensitivity from adult bees following chronic exposure. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

invertebrates with the honeybee. The guidance discusses Tier 1 laboratory-based chronic oral 

toxicity studies of individual honeybee larvae as a critical component of the screening-level risk 

assessment process for examining potential risks from specific routes of exposure. The guidance 

can be found at: http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance.

Additional information on larval honeybee toxicity repeat exposure test design can be found in 

the OECD draft guidance 

http://www.oecd.org/env/ehs/testing/Draft_GD_honeybees_rep_exp_for_2nd_CR_25_Novembe

r_2013.pdf. 

Practical Utility of the Data 

How will the data be used? 

The Tier I chronic oral toxicity data on bee larvae serve as a foundation for the screening-level 

assessment of potential risk to non-target organisms including federally listed threatened or 

endangered and non-listed terrestrial invertebrate insects, including pollinators, from chronic oral 

exposures to pesticides. The data will be used to reduce uncertainties associated with the risk 

assessment for terrestrial invertebrates and will improve EPA’s understanding of the potential 

direct and indirect lethal and sublethal effects on a broad range of terrestrial species, particularly 

insect pollinators. These data will also assist in determining whether early life stages of the bee 

differ in their sensitivity to pesticides relative to adults. If chronic oral effects data for larvae are 

not available, risks to terrestrial insects from chronic oral exposure will be assumed.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether 

continued registration of a pesticide is likely to result in unreasonable adverse effects to nontarget species or is likely to adversely affect listed threatened or endangered species and/or 

modify their designated critical habitat. Without these data, EPA may need to presume risk 

which will limit the flexibility of pesticide products to comply with FIFRA and the ESA, and 

could result in use restrictions. 

Study Title: Pollinator Tier II Semi-Field Toxicity Testing (tunnel/enclosure studies) 

Rationale for Requiring the Data 

Tier II studies are conditional on the outcome of the screening-level assessment where acute 

and/or chronic risk levels of concern have been exceeded for terrestrial invertebrates. Terrestrial 

invertebrates are likely to be impacted if exposed to pesticides in various use settings. Pesticide 

residues may be transferred to pollen and/or nectar of treated plants and subsequently brought 

back to the hive and may adversely affect developing brood (egg, larvae, and pupae) and adult 

bees. Screening-level (Tier I) studies of individual bees do not address possible effects and/or 
-Page 49 of 66- 

exposure to pesticide residues at the colony-level. Because of the potential for pollen and nectar 

to be contaminated with pesticide residues, and subsequently brought back to the hive, it is 

important to determine whether bee colonies may be negatively affected under relatively 

controlled exposure conditions of a semi-field study. In addition to providing effects data, these 

studies can provide data on exposure as pesticide residues in pollen/nectar of treated plants. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

invertebrates with the honeybee. The guidance describes the tiered testing process and can be 

found at: http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 

Additional information on honeybee colony studies under semi-field conditions can be found in 

the OECD Guidance 75 

http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono%28. 

Practical Utility of the Data 

How will the data be used? 

Tier II colony-level data will be used to assess potential risk to non-target organisms including 

listed and non-listed terrestrial social invertebrate species and to determine whether effects 

observed in the screening-level (Tier I) laboratory-based studies of individual bees are evident in 

colony-level studies under semi-field conditions. The Tier II semi-field test of whole colonies is 

a relatively controlled study, i.e., bees are confined to a specific area, that is designed to 

represent potential field-level exposure and account for hive dynamics, which are not achievable 

from other pollinator studies. This study will be used to determine whether adverse effects to 

insect pollinators at the whole colony level, may result for the use of pesticides and will help to 

refine risk estimates derived in the screening-level risk assessment for beneficial terrestrial 

invertebrates. Measured residues in pollen/nectar can also be used to refine risk estimates 

derived from model-based or default values in the screening-level assessment. 

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether 

continued registration of a pesticide is likely to result in unreasonable adverse effects to nontarget species or is likely to adversely affect federally listed threatened or endangered species or 

their designated critical habitat. Without these data, EPA may need to presume risk which will 

limit the flexibility of pesticide products to comply with FIFRA and the ESA, and could result in 

significant use restrictions. 

Study Title: Pollinator Tier II Semi-Field Toxicity Testing (feeding studies) 

Rationale for Requiring the Data 

Pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently 

brought back to the hive, and may adversely affect developing brood (egg, larvae, and pupae) 

and adult bees. Tier II feeding studies are conditional on the outcome of the screening-level 

assessment where acute and/or chronic risk levels of concern have been exceeded for terrestrial 

invertebrates based on Tier I studies of individual bees. Feeding studies utilize free foraging bee 

colonies that are “dosed” with specific quantities of test material and represent a means of 

ensuring exposure to the test material through spiked pollen and/or sugar solutions fed to the 

colony while still allowing the bees to forage freely. Since bee colonies are not confined to 
-Page 50 of 66- 

enclosures, colonies can be exposed for longer duration periods without subjecting the bees to 

stress that typically results from Tier II tunnel studies. Available toxicity studies of individual 

bees (Tier 1) conducted to support screening-level assessments do not address possible effects 

and/or exposure to pesticide residues at the colony-level. Because of the potential for pollen and 

nectar to be contaminated with pesticide residues, and subsequently brought back to the hive, it 

is important to determine whether bee colonies may be negatively affected where bees are free 

foraging and have the option to collect/consume alternative forage items beyond the spiked food. 

Since multiple dose levels can be more readily tested, feeding studies can help to define doseresponse relationships at the whole colony level. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

invertebrates with the honeybee. The guidance describes the tiered testing process and can be 

found at: http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 

Additional information on honeybee colony feeding studies can be found in the EPPO Guidance 

170 at: http://www.nationalbeeunit.com/index.cfm?pageId=187.

Practical Utility of the Data 

How will the data be used? 

Tier II colony feeding data will be used to assess potential risk to non-target organisms including 

listed and non-listed terrestrial social invertebrate species. The colony feeding study is designed 

to represent potential field-level exposure and account for hive dynamics using longer duration 

exposure periods than are possible in Tier II tunnel studies. The study will be used to determine 

whether potential adverse effects to insect pollinators at the whole colony level when bees are 

able to forage naturally beyond the spiked food. Results from the feeding study will help to 

refine the screening-level risk assessment for beneficial terrestrial invertebrates that were based 

on Tier I studies on individual bees. Since feeding studies can help to define a dose-response 

relationship at the colony level, the studies can provide a means of determining exposure 

thresholds below which the likelihood of adverse effects on colonies may be low. 

 

How could the data impact the Agency’s future decision-making?

Tier II colony-level data will be used to refine screening-level risk estimates derived using Tier I 

laboratory-based data on individual bees. The Tier II data will inform the determination required 

under FIFRA or the ESA as to whether continued registration of a pesticide is likely to result in 

unreasonable adverse effects to non-target species or is likely to adversely affect federally listed 

threatened or endangered species or their designated critical habitat. Without these data, EPA 

may need to presume risk which will limit the flexibility of pesticide products to comply with 

FIFRA and the ESA, and could result in significant use restrictions. 

Study Title: Residues in Pollen and Nectar 

Rationale for Requiring the Data 

Terrestrial invertebrates are likely to be impacted if exposed to pesticide residues in various use 

settings. Pesticide residues may be transferred to pollen and/or nectar of treated plants and 

subsequently brought back to hive where all life stages may be exposed. For some pesticides, 

the quantification of pollinator-relevant residues in treated flowering plants is needed, since 

pollinators will be exposed to residues from either current or prior season applications (due to the 

potential for residues to accumulate in plants and trees). Residues in edible/transportable-to-hive 
-Page 51 of 66- 

parts of treated trees and plants, including (where appropriate), but not limited to, guttation 

water, sap/resins, whole plant tissue (e.g., leaves, stems), as well as blooming, pollen-shedding, 

and nectar producing parts (i.e., flowers and, if present, extra-floral nectaries) of plants may 

inform the potential for risk. Studies should be designed to provide residue data for crops and 

application methods of concern. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for 

invertebrates with the honeybee. The guidance can be found at: http://www2.epa.gov/pollinatorprotection/pollinator-risk-assessment-guidance.

Practical Utility of the Data 

How will the data be used? 

Measured residue data will be used to refine conservative estimates of pesticide exposure and 

reduce uncertainties associated with the Tier I exposure assessment by providing direct 

measurements of pesticide concentrations resulting from actual use settings. Measured residues 

may provide a more realistic understanding of exposure through contact or ingestion with which 

to calculate risk quotients for individual bees as well as to characterize exposure to the colony. If 

measured residue data are not available, risk estimates for terrestrial insects will be based on 

model-generated or default values used to support the screening-level assessment.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether 

continued registration of a pesticide is likely to result in unreasonable adverse effects to nontarget species or is likely to adversely affect federally listed threatened or endangered species or 

their designated critical habitat. Without these data, EPA will have to rely on conservative 

estimates of exposure which will limit the flexibility of pesticide products to comply with FIFRA 

and the ESA, and could result in use restrictions. 

9. References 

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA 

food-chain (Kenaga) nomogram, and instrument for estimating pesticide residues on plants. 

Environmental Toxicology and Chemistry 13 (9):1383-1391. 

Hoerger, F., and E.E. Kenaga. 1972. Pesticide residues on plants: Correlation of representative data as a 

basis for estimation of their magnitude in the environment. In F. Coulston and F. Korte, eds., 

Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ, 

Stuttgart, West Germany, pp. 9-28. 

USEPA. 2014a. BEAD Chemical Profile (BCP) for Registration Review: Propoxycarbazone sodium 

(122019). U.S. Environmental Protection Agency, Office of Pesticide Programs, Biological and 

Economic Analysis Division, October 22, 2014. 

USEPA. 2014b. Propoxycarbazone-sodium (122019) Label Use Report Package in Support of 

Registration Review. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Biological and Economic Analysis Division, September 10, 2014. 
-Page 52 of 66- 

USEPA. 2014c. Propoxycarbazone-sodium: Drinking Water Exposure Assessment for Registration 

Review. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. December 4, 2014. DP Barcode: 423552. 

USEPA, PMRA, and CDPR. 2014. Guidance for Assessing Pesticide Risks to Bees. Office of Pesticide 

Programs, USEPA, Washington D.C. Health Canada Pest Management Regulatory Agency, 

Ottawa, ON, Canada. California Department of Pesticide Regulation, Sacramento, CA. June 23, 

2014. 

USEPA. 2013. Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and 

Drinking Water Assessments. U.S. Environmental Protection Agency, Office of Chemical 

Safety and Pollution Prevention, Office of Pesticide Programs, Environmental Fate and Effects 

Division, December 20, 2013. 

USEPA. 2009a. ECOTOXicology Database, v. 4.0. Accessed on 14 November 2014. Available online at 

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

USEPA. 2009b. Ecological Incident Information System, v. 2.1. Accessed on 20 November 2014. 

Description online at http://www.epa.gov/pesticides/science/models_db.htm. 

USEPA. 2009c. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides, Version 2.1. U.S. Environmental Protection Agency, Office of 

Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate 

and Effects Division, October 22, 2009. Online at: 

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

USEPA. 2008. Ecological Risk Assessment Addressing the Proposed Registration of Propoxycarbazonesodium for New Use on Rangeland. U.S. Environmental Protection Agency, Office of Pesticide 

Programs, Environmental Fate and Effects Division. December 17, 2008. DP Barcode: 348511. 

USEPA. 2006. TERRPLANT v. 1.2.2 User’s Guide. Office of Pesticide Programs, Environmental Fate 

and Effects Division, Washington, D.C. December 26, 2006. 

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

Programs, U.S. Environmental Protection Agency. Endangered and Threatened Species Effects 

Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide 

Programs, Washington, D.C., January 23, 2004. Available online at 

http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf. 

USEPA. 2004b. Section 3 Registration Request for Proposed Use of Propoxycarbazone-sodium on 

Wheat. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. March 15, 2004. DP Barcodes: D284671, D284675, D284677, 

D284680, D274582, D274584, D274586, D274588, D294147. 

USEPA. 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. Published in 63 FR 

26846; May 14, 1998. U.S. Environmental Protection Agency, Washington, DC. April, 1998. 
-Page 53 of 66- 

9.1. Submitted Product Chemistry and Environmental Fate Studies 

MRID Citation 

45012634 Fent, G.; Kelly, I. (1997) Adsorption/Desorption of MKH 6561 in Five Soil Types: Lab Project 

Number: M1182101: BAC 01: 107731. Unpublished study prepared by Staatliche Lehr-und 

Forschungsanstalt fur Landwirtschaft, Weinbau und Gartenbau (SLFA). 71 p. 

45012635 Fent, G.; Kelly, I. (1997) Adsorption/Desorption of MKH 6561 Carboxylic Acid (MKH 7018), a 

Degradate of MKH 5461 in Five Soil Types: Lab Project Number: M1182102: BAC02: 107732. 

Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt fuer Landwirtschaft, Weinbau 

und Gartenbau (SLFA). 58 p. 

45012636 Fent, G.; Kelly, I. (1997) Adsorption/Desorption of MKH 6561 Sulfonamide Acid (MKH 7283), a 

Degradate of MKH 6561, in Five Soil Types: Lab Project Number: M1182105: BAC04: 107735. 

Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt fur Landwirtschaft, Weinbau 

und Gartenbau (SLFA). 31 p. 

45012637 Fent, G.; Kelly, I. (1997) Adsorption/Desorption of MKH 6561 Sulfonamide Methyl Ester(STJ 4934), a 

Degradate of MKH 6561, in Five Soil Types: Lab Project Number: M1182104: BAC06: 107734. 

Unpublished study prepared by Staatliche Lehr-und Forschungsanstalt fur Landwirtschaft, Weinbau 

und Gartenbau (SLFA). 26 p. 

45012638 Fent, G.; Kelly, I. (1997) Adsorption/Desorption of Saccharin (MKH 7284), a Degradate of MKH 6561, 

in Five Soil Types: Lab Project Number: M1182103: BAC03: 107733. Unpublished study prepared by 

Staatliche Lehr-und Forschungsanstalt fur Landwirtschaft, Weinbau und Gartenbau (SLFA). 57 p. 

45012701 Mattern, G.; Li, Y.; Wiedmann, J. (1999) Analytical Method for the Determination of MKH 6561 and 

Seven Degradates Soil: Lab Project Number: M2022103: M2022104: 108826. Unpublished study 

prepared by Bayer Corp. and Ricerca, Inc. 57 p. 

45012702 Brumhard, B.; Knoell, H.; Bornatsch, W. (1999) Photolysis of (phenyl-UL-(carbon-14)) MKH 6561 in 

Aqueous Solutions: Lab Project Number: M1120786-5: 109107. Unpublished study prepared by Bayer 

AG. 70 p. 

45012703 Brumhard, B.; Knoell, H.; Bornatsch, W. (1999) Photolysis of (Triazolinone-3-(carbon-14)) MKH 6561 

in Aqueous Solutions: Lab Project Number: 109108: M1120787-6. Unpublished study prepared by 

Bayer AG. 64 p. 

45012704 Riegner, K. (1998) Aerobic Aquatic Degradation and Metabolism of MKH 6561 in Water-Sediment 

System: Lab Project Number: M1510785-7: 109112. Unpublished study prepared by Bayer AG. 83 p. 

45012705 Hellpointer, E. (1998) Determination of the Volatisation Behaviour of MKH 6561 (WG 70) in a Field 

Trial: Lab Project Number: 109113: M1180924-5. Unpublished study prepared by Bayer AG. 41 p. 

45012706 Blumhorst, M.; Bloomberg, A. (1999) Aerobic Degradation of N-Methyl Propoxy Triazolinone Amide 

(A Metabolite of MKH 6561) in Three Soils: Lab Project Number: M1042109: 122S28: 108703. 

Unpublished study prepared by EPL-Bio-Analytical Services, Inc. 77 p. 

45012707 Arthur, E.; O'Brien, B.; Parker, G. et al. (1999) Anaerobic Aquatic Metabolism of (Phenyl-U-(carbon14)) MKH 6561 in a Washington Water and Sediment Test System: Lab Project Number: M1042401: 

108916. Unpublished study prepared by Bayer Corp. 72 p. 

45012708 Arthur, E.; O'Brien, B.; Parker, G. et al. (1999) Anaerobic Aquatic Metabolism of (Triazolinone-3-

(carbon-14))MKH 6561 in a Washington Water and Sediment Test System: Lab Project Number: 

108917: M1042402. Unpublished study prepared by Bayer Corp. 72 p. 

45012709 Hein, W.; Wujcik, C. (1999) Adsorption/Desorption of (Phenyl-U-(carbon-14))4-Hydroxy Saccharin, a 

Degradate of MKH 6561 in Five Soil Types: Lab Project Number: M1182107: BAC16: 108700. 

Unpublished study prepared by SLFA. 79 p. 

45012710 Bruns, G.; Hoshowski, J. (1999) Independent Laboratory Validation of the Analytical Method for the 

Determination of MKH 6561 and Seven Degradates in Soil: Lab Project Number: M1112101: 109124: 

108826-1. Unpublished study prepared by Enviro-Test Labs. 102 p. 
-Page 54 of 66- 

45012711 Blumhorst, M.; Bloomberg, A. (1999) Aerobic Degradation N-Methyl Propoxy Trizolinone (a 

Metabolite of MKH 6561) in Quincy Loamy Sand from Ephrata, WA: Lab Project Number: 

M1042111: 122S30: 108705. Unpublished study prepared by EPL Bio-Analytical Services, Inc. 47 p. 

45012712 Blumhorst, M.; Bloomberg, A. (1999) Aerobic Degradation Saccharin (a Metabolite of MKH 6561) in 

Quincy Loamy Sand from Ephrata, WA: Lab Project Number: M1042110: 122S29: 108704. 

Unpublished study prepared by EPL Bio-Analytical Services, Inc. 47 p. 

45012713 Hein, W.; Wujcik, C. (1999) Adsorption/Desorption of N-Methyl Propoxy Triazolinone Amide a 

Degradate of MKH 6561, in Five Soil Types: Lab Project Number: M1182108: BAC15: 108701. 

Unpublished study prepared by SLFA. 82 p. 

45012714 Blumhorst, M.; Bloomberg, A. (1999) Aerobic Degradation of 4-Hydroxy Saccharin (a Metabolite of 

MKH 6561) in Three Soils: Lab Project Number: 108702: 122S27: M1042108. Unpublished study 

prepared by EPL-Bio-Analytical Services, Inc. 71 p. 

45012715 Wood, S. (1999) Terrestrial Field Dissipation of MKH 6561 in Washington Soil, 1996: Lab Project 

Number: 108734: M1022103: 98-B-263. Unpublished study prepared by Qualls Agricultural Labs. and 

Ricerca, Inc. 296 p. 

45012716 Wood, S.; Koch, D. (1999) Terrestrial Field Dissipation of MKH 6561 in Kansas Soil, 1996: Lab 

Project Number: 108736: 98-B-265: M1022104. Unpublished study prepared by Qualls Agricultural 

Labs. and Ricerca, Inc. 321 p. 

45012717 Malekani, K., and R. Ripperger. 1999. Freezer stability of 4-hydroxy saccharin and N-methyl propoxy 

triazolinone amide (MKH 6561 Metabolites) in Quincy loamy sand. Unpublished study performed by 

Bayer Corporation, Stilwell, KS 

45012718 Smith, D.M., D.L. Green, and C.E. Wujcik. 1999. Freezer stability of [phenyl-u-14C]MKH 6561 and 

five metabolites in Quincy loamy sand. Unpublished study performed by Bayer Corporation, Stilwell, 

KS; and submitted by Bayer Corporation, Kansas City, MO. Bayer Study No. M 1 132 10 1, Bayer 

Report No. 108846. Experimental start date November 2 1, 1996, and completion date February 8, 1999 

(p. 13). Final report issued July 2 1, 1999. 

45012718 Smith, D.M., D.L. Green, and C.E. Wujcik. 1999. Freezer stability of [phenyl-U-14C]MKH 6561 and 

five metabolites in Quincy loamy sand. Unpublished study performed by Bayer Corporation, Stilwell, 

KS; and submitted by Bayer Corporation, Kansas City, MO. 

45012719 Koch, D.; Wood, S. (1999) Terrestrial Field Dissipation of MKH 6561 in Utah Soil, 1997: Lab Project 

Number: 108735: 98-B-264: M1022102. Unpublished study prepared by Bayer Corp. and ABC Labs. 

282 p. 

45012720 Helfrich, K.; Bloomberg, A.; Ripperger, R. (1999) Aerobic Metabolism of (Phenyl-U-(carbon 

14))MKH 6561 in Quincy Loamy Sand from Ephrata Washington: Lab Project Number: 107650: 

M1042101. Unpublished study prepared by Bayer Corp. 59 p. 

45012721 Henry, T.; Bloomberg, A.; Ripperger, R. (1999) Aerobic Metabolism of (Triazolinone-3-(carbon 

14))MKH 6561 in Three German Soils: Lab Project Number: M1042107: 108727. Unpublished study 

prepared by Bayer Corp. 76 p. 

45012722 Helfrich, K.; Bloomberg, A.; Ripperger, R. et al. (1999) Aerobic Metabolism of (Phenyl-U-(carbon 

14))MKH 6561 in Three German Soils: Lab Project Number: 107652: M1042106. Unpublished study 

prepared by Bayer Corp. 92 p. 

45012723 Helfrich, K.; Bloomberg, A.; Ripperger, R. et al. (1999) Aerobic Metabolism of (Triazolinone-3-

(carbon 14))MKH 6561 in Quincy Loamy Sand from Ephrata, Washington: Lab Project Number: 

107651: M1042103. Unpublished study prepared by Bayer Corp. 63 p. 

45012724 Knoell, H.; Brumhard, B. (1999) Hydrolysis of (Triazolinone-3-(carbon 14))MKH 6561 in Sterile 

Aqueous Solutions: Lab Project Number: 109222: M1110777-4. Unpublished study prepared by Bayer 

AG. 56 p. 

45012725 Knoell, H.; Brumhard, B. (1999) Hydrolysis of (Triazolinone-3-(carbon 14))MKH 6561 in Sterile 

Aqueous Solutions: Lab Project Number: 10922-1: M111077-4. Unpublished study prepared by Bayer 

AG. 15 p. 
-Page 55 of 66- 

45012726 Shadrick, B.; Ripperger, R.; Bloomberg, A. (1999) The Leaching Potential of (Phenyl-U-(carbon 

14))MKH 6561 in Sulfonamide Methyl Ester (STJ 4934) in Quincy Loamy Sand: Lab Project Number: 

108718: M1092102. Unpublished study prepared by Bayer Corp. 42 p. 

45012727 Henry, T.; Ripperger, R.; Bloomberg, A. et al. (1999) Leaching Potential of Aged MKH 6561 Residues 

in Quincy Loamy Sand: Lab Project Number: 108841: M1092101. Unpublished study prepared by 

Bayer Corp. 80 p. 

45012728 Brumhard, B.; Knoell, H. (1999) Photolysis of (Triazolinone-3-(carbon 14))MKH 6561 on Soil 

Surfaces: Lab Project Number: M1130798-9: 109244. Unpublished study prepared by Bayer AG. 58 p. 

45012729 Brumhard, B.; Knoell, H. (1999) Photolysis of (Phenyl-UL-(carbon 14))MKH 6561 on Soil Surfaces: 

Lab Project Number: 109243: M1130780-0. Unpublished study prepared by Bayer AG. 57 p. 

45012730 Brumhard, B.; Knoell, H. (1999) Photolysis of (Phenyl-UL-(carbon 14))MKH 7284 in Aqueous 

Solutions: Lab Project Number: 109245: M1120834-9. Unpublished study prepared by Bayer AG. 52 p. 

45012731 Fent, G.; Kelley, I. (1997) Adsorption/Desorption of N-Methyl Propoxy Triazolinone (MKH 7017), a 

Degradate of MKH 6561, in Five Soil Types: Lab Project Number: BAC05: 107736. Unpublished study 

prepared by SLFA. 57 p. 

45012732 Brumhard, B. (1998) Method for the Determination of MKH 6561 in Drinking Water by HPLC Using 

Injection as Well as On-Line Solid Phase Extraction: Lab Project Number: MR-741/98: 109114. 

Unpublished study prepared by Bayer AG. 22 p. 

45012733 Brumhard, B.; Knoell, H. (1999) Hydrolysis of (Phenyl-(carbon 14))MKH 6561 in Sterile Aqueous 

Buffer Solutions: Lab Project Number: M1110776-3: 109127. Unpublished study prepared by Bayer 

AG. 68 p. 

45012734 Hellpointer, E. (1997) Determination of the Quantum Yield and Assessment of the Environmental HalfLife of the Direct Photodegradation of MKH 6561 in Water: Lab Project Number: M1430772-4: 

109450. Unpublished study prepared by Bayer AG. 32 p. 

45012735 Schafer, H. (1999) Calculation of DT-50 Values of MKH 6561 Metabolite MKH 7017 in Soil Under 

Aerobic Conditions: Lab Project Number: P66896546: 109396. Unpublished study prepared by Bayer 

AG. 17 p. 

45012736 Schafer, H. (1999) Calculation of DT-50 Values of MKH 6561 Metabolite MKH 7284 and STJ 4934 in 

Soil Under Aerobic Conditions: Lab Project Number: 109397: P66896546. Unpublished study prepared 

by Bayer AG. 23 p. 

45012737 Fritz, R. and K. Spiegel. 1999. Lysimeter study on the degradation and translocation of the herbicide 

MKH 6561 under field conditions. Unpublished study performed by Bayer AG, Crop Protection 

Business Group, Crop Protection-Development, Germany. 

45012738 Schramel, 0 . 1999. Dissipation of MKH 6561 (70 WG) in soil under field conditions (France, 

Germany, Great Britain). Unpublished study performed by Bayer AG, Crop Business Group, Crop 

Protection-Development, Leverkusen, Germany, 

45012739 Schramel, 0. 1999. Amendment to report: Dissipation of MKH 6561 (70 WG) in soil under field 

conditions (France, Germany, Great Britain). Unpublished study performed by Bayer AG, Crop 

Protection Business Group, Crop Protection Development, Schramel, 0 . 1999. Dissipation of MKH 

6561 (70 WG) in soil under field conditions (France, Germany, Great Britain). Unpublished study 

performed by Bayer AG, Crop Business Group, Crop Protection-Development, Leverkusen, Germany, 

45012740 Schafer, H. (1999) Calculation of DT-50 of MKH 6561 Metabolite STJ 4934 Generated by Hydrolysis 

in Sterile Aqueous Buffer Solutions: Lab Project Number: 109398: P68896511. Unpublished study 

prepared by Bayer AG. 14 p. 

46874601 Gould, T. (2006) Freezer Storage Stability of MKH 6561 and Pr-2-OH MKH 6561 in Turnip Tops, 

Turnip Tops, Turnip Roots, and Mustard Greens. Project Number: RAMIY001, M1131601. 

Unpublished study prepared by Bayer Corp. 62 p. 
-Page 56 of 66- 

9.2. Submitted Ecotoxicity Studies 

MRID Citation 

45012505 Pauluhn, J. (1995) MKH 6561 Study on Acute Inhalation Toxicity in Rats According to OECD No. 

403: Lab Project Number: 23897: T4055671: 107402. Unpublished study prepared by Bayer AG. 53 p. 

45012509 Krotlinger, F. (1994) MKH 6561 Study for Acute Oral Toxicity in Rats: Lab Project Number: 23480: 

T8055657: 107412. Unpublished study prepared by Bayer AG. 29 p. 

45012529 Eiben, R. (1999) MKH 6561 (c.n.: Procarbazone-Sodium) Two-Generation Study in Wistar Rats: Lab 

Project Number: 109096: 28792: T1061527. Unpublished study prepared by Bayer AG. 997 p. {OPPTS 

870.3800} 

45012801 Drottar, K.; Krueger, H. (1998) MKH 6561 Technical: A Flow-Through Life-Cycle Toxicity Test with 

the Saltwater Mysid (Mysidopsis bahia): Lab Project Number: 149A-112: 108108. Unpublished study 

prepared by Wildlife International Ltd. 55 p. 

45012802 Bowers, L.; Lam, C. (1999) Chronic Toxicity of MKH 6561 Technical to the Waterflea (Daphnia 

magna) Under Static Renewal Conditions: Lab Project Number: M1840702: 108845. Unpublished 

study prepared by Bayer Corporation. 51 p. 

45012803 Bowers, L. (1999) Toxicity of MKH 6561 Technical to the Blue-Green Alga Anabaena flos-aquae: Lab 

Project Number: M1883801: 107718. Unpublished study prepared by Bayer Corporation. 30 p. 

45012804 Palmer, S.; Krueger, H. (1998) MKH 6561 Technical: A 96 Hour Flow-Through Acute Toxicity Test 

with the Saltwater Mysid (Mysidopsis bahia): Lab Project Number: 149A-110: 108112. Unpublished 

study prepared by Wildlife International, Ltd. 44 p. 

45012805 Palmer, S.; Krueger, H. (1998) MKH 6561 Technical: A 96 Hour Shell Deposition Test with the 

Eastern Oyster (Crassostrea virginica): Lab Project Number: 149A-111: 108121. Unpublished study 

prepared by Wildlife International, Ltd. 44 p. 

45012806 Hall, A. (1997) Acute Toxicity of MKH 6561 Technical to the Bluegill (Lepomis microchirus) Under 

Static-Renewal Conditions: Lab Project Number: M1810301: 107748. Unpublished study prepared by 

Bayer Corporation. 29 p. 

45012807 Bowers, L.; Lam, C. (1998) Toxicity of MKH 6561 Technical to the Freshwater Diatom Navicula 

pelliculosa: Lab Project Number: M1883401: 108487. Unpublished study prepared by Bayer 

Corporation. 32 p. 

45012808 Bowers, L. (1998) Acute Toxicity of MKH 6561 Technical to the Waterflea (Daphnia magna) under 

Static Conditions: Lab Project Number: M1820701: 107841. Unpublished study prepared by Bayer 

Corporation. 28 p. 

45012809 Hall, A. (1998) Acute Toxicity of MKH 6561 Technical to the Rainbow Trout (Oncorhynchus mykiss) 

Under Static Conditions: Lab Project Number: M1812201: 108066. Unpublished study prepared by 

Bayer Corporation. 29 p. 

45012810 Hall, A. (1998) Acute Toxicity of MKH 6561 Technical to the Sheepshead Minnow (Cyprinodon 

variegatus) Under Static Conditions: Lab Project Number: M1832801: 108065. Unpublished study 

prepared by Bayer Corporation. 30 p. 

45012811 Bowers, L.; Lam, C. (1998) Chronic Toxicity of MKH 6561 Technical to the Waterflea (Daphnia 

magna) Under Static Renewal Conditions: Lab Project Number: M1840701: 108140. Unpublished 

study prepared by Bayer Corporation. 46 p. 

45012812 Bowers, L.; Lam, C. (1999) Toxicity of MKH 6561 Technical to the Marine Diatom Skeletonema 

costatum: Lab Project Number: M1883601: 108493. Unpublished study prepared by Bayer 

Corporation. 32 p. 

45012813 Hancock, G. (1999) MKH 6561 Technical: An Acute Oral LD50 with Northern Bobwhite: Lab Project 

Number: M1711701: 108741. Unpublished study prepared by Bayer Corporation. 33 p. 
-Page 57 of 66- 

45012814 Bowers, L.; Lam, C. (1999) Toxicity of MKH 6561 Technical to the Green Alga Selenastrum 

capricornutum: Lab Project Number: M1883501: 108820. Unpublished study prepared by Bayer 

Corporation. 33 p. 

45012815 Bowers, L.; Lam, C. (1999) Toxicity of MKH 6561 Technical to Lemna gibba G3: Lab Project 

Number: M1883701: 108338. Unpublished study prepared by Bayer Corporation. 35 p. 

45012816 Hancock, G. (1999) Technical MKH 6561: A Subacute Dietary LC50 with Northern Bobwhite: Lab 

Project Number: M1721701: 108802. Unpublished study prepared by Bayer Corporation. 48 p. 

45012817 Hall, A.; Lam, C. (1999) Early Life Stage Toxicity of MKH 6561 to the Fathead Minnow (Pimephales 

promelas): Lab Project Number: M1851201: 108453. Unpublished study prepared by Bayer 

Corporation. 55 p. 

45012818 Schmitzer, S. (1998) Laboratory Testing for Toxicity (Acute Contact and Oral LD50) of MKH 6561 on 

Honey Bees (Apis mellifera L.) (Hymenoptera, Apidae): Lab Project Number: 4150036: 109135. 

Unpublished study prepared by Institute for Biological Analysis and Consulting IBACON GmbH. 30 p. 

45012821 Hancock, G.; Webster, C. (1999) Technical MKH 6561: A Subacute Dietary LC50 with Mallards: Lab 

Project Number: M1720801: 109144. Unpublished study prepared by Bayer Corporation. 48 p. 

45012822 Dorgerloh, M. (1999) MKH 8394 (A Metabolite of MKH 6561)-Toxicity (7 Days) to Lemna gibba G3: 

Lab Project Number: E 412 1440-6: 109223: DOM 98094. Unpublished study prepared by Bayer AG. 

40 p. 

45012823 Hancock, G.; Hansen, C.; Hall, A. (1999) Tier 2 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 6561 70WG Formulation: Lab Project Number: M1201601: 108843. 

Unpublished study prepared by Bayer Corporation. 110 p. 

45012825 Heimbach, F. (1998) Acute Toxicity of MKH 6561 (tech) to Earthworms (Eisenia fetida): Lab Project 

Number: E 310 1400-9: 109369. Unpublished study prepared by Bayer AG. 18 p. 

45012826 Heimbach, F. (1998) Acute Toxicity of MKH 7017 (A Metabolite of MKH 6561) to Water Fleas 

(Daphnia magna): Lab Project Number: 109367: E 320 1426-8. Unpublished study prepared by Bayer 

AG. 26 p. 

45012827 Dorgerloh, M. (1998) MKH 7017 (A Metabolite of MKH 6561)-Acute Toxicity (96 Hours) to Bluegill 

(Lepomis macrochirus) in a Static Test: Lab Project Number: 109363: E 252 1419-4: DOM 98052. 

Unpublished study prepared by Bayer AG. 44 p. 

45012828 Dorgerloh, M. (1998) MKH 8394 (Free Acid of MKH 7018, a Metabolite of MKH 6561)-Acute 

Toxicity (96 Hours) to Bluegill (Lepomis macrochirus) in a Static Test: Lab Project Number: E 252 

1418-3: 109364: DOM 98054. Unpublished study prepared by Bayer AG. 44 p. 

45012829 Heimbach, F. (1998) Acute Toxicity of MKH 8394 (Free Acid of MKH 7018, a Metabolite of MKH 

6561) to Water Fleas (Daphnia magna): Lab Project Number: 109368: E 320 1427-9: HBF/DM 199. 

Unpublished study prepared by Bayer AG. 26 p. 

45012830 Dorgerloh, M. (1998) MKH 7017 (a Metabolite of MKH 6561) Toxicity (7 Days) to Lemna gibba G3: 

Lab Project Number: E 412 1441-7: 109366: DOM 98114. Unpublished study prepared by Bayer AG. 

31 p. 

45012831 Dorgerloh, M. (1998) MKH 6561 WG 70-Influence on the Growth of the Green Alga, Selenastrum 

capricornutum: Lab Project Number: E 323 1396-7: 109360. Unpublished study prepared by Bayer AG. 

38 p. 

45012832 Gallagher, S.; Martin, K.; Beavers, J. et al. (1999) MKH 6561 Technical: A Reproduction Study with 

the Mallard (Anas platyrhynchos): Lab Project Number: 149-180: 109381. Unpublished study prepared 

by Bayer AG. 156 p. 

45012833 Dorgerloh, M. (1998) MKH 7017 (a Metabolite of MKH 6561)-Influence on the Growth of the Green 

Alga, Selenastrum capricornutum: Lab Project Number: E 323 1393-4: 109361: DOM 98049. 

Unpublished study prepared by Bayer AG. 30 p. 

45012834 Dorgerloh, M. (1999) MKH 8394 (Free Acid of MKH 7018, a Metabolite of MKH 6561)-Influence on 

the Growth of Green Alga, Selenastrum capricornutum: Lab Project Number: E 323 1394-5: 109362: 

DOM 98051. Unpublished study prepared by Bayer AG. 30 p. 
-Page 58 of 66- 

45012835 Batscher, R. (1999) Acute Toxicity of MKH 7284 (a Metabolite of MKH 6561) to Earthworms (Eisenia 

Fetida): Lab Project Number: 736672: 109359. Unpublished study prepared by RCC Ltd. 32 p. 

45012836 Batscher, R. (1999) Acute Toxicity of STJ 4934 (a Metabolite of MKH 6561) to Earthworms (Eisenia 

Fetida): Lab Project Number: 736661: 109358. Unpublished study prepared by RCC Ltd. 31 p. 

45012837 Heimbach, F. (1999) Influence of MKH 6561 WG 70 on the Reproduction of Earthworms (Eisenia 

fetida): Lab Project Number: 109370: E 312 1403-4: HBF/RG 282. Unpublished study prepared by 

Bayer AG. 22 p. 

45012838 Schmitzer, S. (1998) Laboratory Testing for Toxicity (Acute Contact and Oral LD50) of MKH 6561 70 

WG on Honey Bees (Apis mellifera L.) (Hymenoptera, Apidae): Lab Project Number: 4160036: 

109386. Unpublished study prepared by Institute for Biological Analysis and Consulting IBACON 

GmbH. 27 p. 

49072701 Shepherd, J.; Christ, M. (2013) Toxicity of MKH6561 (Propoxycarbazone-sodium) Technical during an 

Acute Oral LD50 with the Canary (Serimus canaria). Project Number: M/449837/01/1/OCR, 

07SRLS13C6, EBMIL004. Unpublished study prepared by SynTech Research Laboratory Services, 

LLC. 35p. 

49072702 Christ, M.; Moore, S. (2013) Toxicity of MKH6561 (Propoxycarbazone-sodium) on Reproduction to 

the Northern Bobwhite Quail (Colinus virginianus). Project Number: M/449836/01/1, 

EBMIL003/OCR. Unpublished study prepared by SynTech Research Laboratory Services, LLC. 71p. 

 
-Page 59 of 66- 

Appendix A. SWCC Modeling Summary for Propoxycarbazone-sodium 

Estimated Environmental Concentrations for Propoxycarbazone are presented in Table A-1 for 

the USEPA standard pond with the TXwheatOP field scenario. A graphical presentation of the 

year-to-year peaks is presented in Figure A-1. These values were generated with the Surface 

Water Concentration Calculator (SWCC Version 1.106). Critical input values for the model are 

summarized in Tables A-2 and A-3. 

This model estimates that about 4.4% of Propoxycarbazone applied to the field eventually 

reaches the water body. The main mechanism of transport from the field to the water body is by 

runoff (71.3% of the total transport), followed by spray drift (28.6%) and erosion (0.11%). 

In the water body, pesticide dissipates with an effective water column half-life of 131.1 days. 

(This value does not include dissipation by transport to the benthic region; it includes only 

processes that result in removal of pesticide from the complete system.) The main source of 

dissipation in the water column is metabolism (effective average half-life = 181.8 days) followed 

by hydrolysis (495 days), photolysis (9397.3 days), and volatilization (2.752516E+07 days). 

In the benthic region, pesticide dissipates very slowly (537.8 days). The main source of 

dissipation in the benthic region is metabolism (effective average half-life = 1053.4 days) 

followed by hydrolysis (1098.8 days). The pesticide is about evenly distributed in the benthic 

region between the pore water and sorbed to sediment. 

Table A-1. Estimated Environmental Concentrations (ppb) for Propoxycarbazone. 

Peak (1-in-10 yr) 2.29 

4-day Avg (1-in-10 yr) 2.27 

21-day Avg (1-in-10 yr) 2.19 

60-day Avg (1-in-10 yr) 2.03 

365-day Avg (1-in-10 yr) 0.973 

Entire Simulation Mean 0.646 

Table A-2. Summary of Model Inputs for Propoxycarbazone. 

Scenario TXwheatOP 

Cropped Area Fraction 1 

Koc (ml/g) 0.4518 

Water Half-Life (days) @ 20 °C 199.35 

Benthic Half-Life (days) @ 20 °C 1155 

Photolysis Half-Life (days) @ 30 °Lat 93.5 

Hydrolysis Half-Life (days) 495 

Soil Half-Life (days) @ 20 °C 107.463 

Foliar Half-Life (days) 35 
-Page 60 of 66- 

Molecular Wt 420 

Vapor Pressure (torr) 7.1e-11 

Solubility (mg/l) 42000 

Table A-3. Application Schedule for Propoxycarbazone. 

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift 

6/16 Foliar 0.0294 0.95 0.125 

10/1 Foliar 0.0294 0.95 0.125 

Figure A-1. Yearly Peak Concentrations 
-Page 61 of 66- 

Appendix B. Example T-REX Input and Output for Propoxycarbazone-sodium 

TREX MODEL INPUTS 

You must enable macros for this spreadsheet to work 

correctly 

These values will be used in the calculation of exposure estimates for foliar, granular, liquid and/or 

seed applications of pesticides. 

 

Chemical Identity and Application Information 

Chemical Name: Propoxycarbazone-sodium 

Seed Treatment? (Check if yes) FALSE 

 Use: Agricultural Fallow/Conservation Reserve, Pastures, and Rangeland 

Product name and form: 

% A.I. (leading zero must be entered for 

formulations <1% a.i.): 100.00% 

Application Rate (lb ai/acre) 0.0525 

Half-life (days): 35 

Application Interval (days): 

Number of Applications: 1 

Are you assessing applications with variable 

rates or intervals? no 

 

Assessed Species Inputs (optional, use defaults for RQs for national level assessments) 

What body weight range is assessed (grams)? Birds Mammals 

Small 20 15 

Medium 100 35 

Large 1000 1000 

 
-Page 62 of 66- 

Endpoints 

Avian 

Endpoint Toxicity value 

Indicate test species 

below 

LD50 (mg/kg-bw) 2000.00 1  

LC50 (mg/kg-diet) 

10339.00 2 

 

NOAEL (mg/kg-bw) 

 2 

 

NOAEC (mg/kg-diet) 

268.00 2 

 

Enter the Mineau et al. Scaling Factor 1.15 

Mammalian Acute Study Chronic Study 

Size (g) of mammal used in toxicity study 

Default rat body weight is 350 grams 350 350 

Endpoint Toxicity value Reference (MRID)

LD50 (mg/kg-bw) 5000.00 

LC50 (mg/kg-diet) 

Reported Chronic Endpoint 297.10 

1 

Is dietary concentration 

(mg/kg-diet) reported from the 

available chronic mammal 

study? (yes or no) 

no 

 

Enter dietary concentration 

(mg/kg-diet) 

Estimated Chronic Diet 

Concentration Equivalent to 

Reported Chronic Daily Dose 

5942 

mg/kg-diet based on 

standard FDA lab rat 

conversion 

 
-Page 63 of 66- 

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs 

Table X. Upper Bound Kenaga, Acute Avian Dose-Based Risk Quotients 

Size 

Class 

(grams) 

Adjust

ed 

LD50 

EECs and RQs 

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

20 

1440.8

6 14.35 0.01 6.58 0.00 8.07 0.01 0.90 0.00 5.62 0.00 0.20 0.00 

100 

1834.2

9 8.18 0.00 3.75 0.00 4.60 0.00 0.51 0.00 3.21 0.00 0.11 0.00 

1000 

2591.0

0 3.66 0.00 1.68 0.00 2.06 0.00 0.23 0.00 1.43 0.00 0.05 0.00 

Table X. Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients 

LC50 

EECs and RQs 

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

10339 12.60 0.00 5.78 0.00 7.09 0.00 0.79 0.00 4.94 0.00 

Size class not used for dietary risk quotients 

Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients 

NOAEC 

(ppm) 

EECs and RQs 

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

268 12.60 0.05 5.78 0.02 7.09 0.03 0.79 0.003 4.94 0.02 

Size class not used for dietary risk quotients 

Table X. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients 

Size 

Class 

(grams) 

Adjust

ed 

LD50 

EECs and RQs 

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

15 10989 12.01 0.00 5.51 0.00 6.76 0.00 0.75 0.00 4.705 0.0004 0.167 2E-05 

35 8891 8.30 0.00 3.81 0.00 4.67 0.00 0.52 0.00 3.252 0.0004 0.115 1E-05 

1000 3846 1.93 0.00 0.88 0.00 1.08 0.00 0.12 0.00 0.754 0.0002 0.027 7E-06 

Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients 

NOAEC 

(ppm) 

EECs and RQs 

Short Grass Tall Grass Broadleaf 

Plants 

Fruits/Pods/Seeds/L

arge Insects Arthropods 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

5942 12.60 0.00 5.78 0.00 7.09 0.00 0.79 0.00 4.94 0.00 

Size class not used for dietary risk quotients 

Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients 

Size 

Class 

(grams) 

Adjust

ed 

NOAE

L 

EECs and RQs 

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

15 652.98 12.01 0.02 5.51 0.01 6.76 0.01 0.75 0.00 4.71 0.01 0.17 0.00 

35 528.33 8.30 0.02 3.81 0.01 4.67 0.01 0.52 0.00 3.25 0.01 0.12 0.00 

1000 228.52 1.93 0.01 0.88 0.00 1.08 0.00 0.12 0.00 0.75 0.00 0.03 0.00 
-Page 64 of 66- 

Appendix C. Example TERRPLANT (v. 1.2.2) Input and Output for Propoxycarbazonesodium 

Table 1. Chemical Identity. 

Parameter User Inputs 

Chemical Name Propoxycarbazone-sodium 

PC code 122019 

Use 

Agricultural Fallow/Conservation Reserve, Pastures, and 

Rangeland 

Application Method Broadcast - aerial 

Application Form liquid 

Solubility in Water (ppm) 42000 

 

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value (user inputs) Units 

Application Rate A 0.0525 a.e. 

Incorporation I 1 none 

Runoff Fraction R 0.05 none 

Drift Fraction D 0.05 none 

 

Table 3. EECs for Propoxycarbazone-sodium. Units in a.e.. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.002625 

Runoff to semi-aquatic areas (A/I)*R*10 0.02625 

Spray drift A*D 0.002625 

Total for dry areas ((A/I)*R)+(A*D) 0.00525 

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.028875 

 

Table 4. Plant survival and growth data used for RQ derivation. Units are in a.e.. All values are user inputs 

 Seedling Emergence Vegetative Vigor 

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 0.00045 0.000034 0.00065 0.000063 

Dicot 0.00058 0.00021 0.00049 0.00021 

 

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Propoxycarbazone-sodium through 

runoff and/or spray drift.* 

Plant Type Listed Status Dry Semi-Aquatic Spray Drift 

Monocot non-listed 11.67 64.17 5.83 

Monocot listed 154.41 849.26 77.21 

Dicot non-listed 9.05 49.78 5.36 

Dicot listed 25.00 137.50 12.50 

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group. 
-Page 65 of 66- 

Appendix D. STIR Results for Propoxycarbazone-sodium 

Input 

Application and Chemical Information 

Enter Chemical Name Propoxycarbazone 

Enter Chemical Use Herbicide 

Is the Application a Spray? (enter y or n) y 

If Spray What Type (enter ground or air) ground 

Enter Chemical Molecular Weight (g/mole) 420.37 

Enter Chemical Vapor Pressure (mmHg) 7.10E-11 

Enter Application Rate (lb a.i./acre) 0.0525 

 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 2000 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 0.178 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000 

Enter Lowest Rat Inhalation LC50 (mg/L) 5.03 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.61E-06 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.02E-07 

Adjusted Inhalation LD50 1.12E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.80E-08 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 5.55E-03 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 4.95E-04 Exposure not Likely Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.61E-06 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.54E-07 

Adjusted Inhalation LD50 2.99E+02 

Ratio of Vapor Dose to Adjusted Inhalation LD50 8.48E-10 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 6.97E-03 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 2.33E-05 Exposure not Likely Significant 
-Page 66 of 66- 

Appendix E. SIP Results for Propoxycarbazone-sodium 

Table 1. Inputs 

Parameter Value 

Chemical name Propoxycarbazone 

Solubility (in water at 25oC; mg/L) 42000 

 

Mammalian LD50 (mg/kg-bw) 5000 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian 

species 

 

Mammalian NOAEL (mg/kg-bw) 297.1 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian 

species 

 

Avian LD50 (mg/kg-bw) 2000 

Avian test species northern bobwhite quail 

Body weight (g) of "other" avian species 

Mineau scaling factor 1.15 

 

Mallard NOAEC (mg/kg-diet) 268 

Bobwhite quail NOAEC (mg/kg-diet) 324 

 

Table 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 7224.0000 7224.0000 

Adjusted toxicity value (mg/kg-bw) 3845.8028 228.5176 

Ratio of exposure to toxicity 1.8784 31.6124 

Conclusion* 

Exposure through 

drinking water alone is 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) 34020.0000 34020.0000 

Adjusted toxicity value (mg/kg-bw) 1440.8590 13.2962 

Ratio of exposure to acute toxicity 23.6109 2558.6322 

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.