By: 

Ecological Risk Assessment 

Section 3 (New Use on Sorghum) 

Propazine 

(PC Code 080808, CASN 139-40-2) 

IUPAC Name: 6-chloro-N2,N4-di-isopropyl-6-methylthio-1,3,5-triazine-2,4-diamine 

Pamela M. Hurley, Senior Toxicologist 

Mark Corbin, Senior Environmental Scientist 

Ecological Risk Branch 111 

Environmental Fate and Effects Division 

Branch Chief: Daniel Rieder 

Ecological Risk Branch 111 

Environmental Fate and Effects Division 

Date: November 3,2006 

Text Searchable Document
TABLE OF CONTENTS 

I. EXECUTIVE SUMMARY .............................................................................................................. - 6 

A. Nature of Chemical Stressor ....................................................................................................... 6 

B. Potential Risks to Non-target Organisms.. ..................................................................................... 6 

C. Conclusions - Exposure Characterization ..................................................................................... a 

D. Conclusions - Effects Characterization.. ..................................................................................... .u 

E. Uncertainties and Data Gaps.. ................................................................................................... .u 

11. PROBLEM FORMULATION ........................................................................................................ .s 

A. Stressor Source and Distribution ................................................................................................ I . Source and Intensity ......................................................................................................... .u 

2. Physical/Chemical/Fate and Transport Properties .................................................................... 3. Pesticide Type, Class and Mode of Action ............................................................................. & 

4. Overview of Pesticide Usage ............................................................................................... B. Receptors.. ............................................................................................................................ .u 

1. Aquatic Effects ................................................................................................................. 2. Terrestrial Effects., .......................................................................................................... ..u 

3. Ecosystems at Risk ............................................................................................................ 14- 

C. Assessment Endpoints.. .......................................................................................................... .B 

D. Conceptual Model ................................................................................................................... a 

1. Risk Hypotheses .......................................................................................................... .....a 

2. Diagram ......................................................................................................................... .d 

E. Analysis Plan ........................................................................................................................ .z 

111. ANALYSIS. ............................................................................................................................... ,g 

A. Use Characterization.. ............................................................................................................. .27 -

B. Exposure Characterization ........................................................................................................ 3 

1. Environmental Fate and Transport Characterization ................................................................. 3 

a. Summary of Empirical Data .......................................................................................... 3 

b. Degradation and Metabolism ........................................................................................ .?O 

c. Transport and Mobility ................................................................................................. 3 

d. Field Studies ............................................................................................................. .3 - I 

e. Review of Published Literature on the Environmental Fate of Propazine ................................ 31 

2. Measures of Aquatic Exposure ............................................................................................. 3 

a. Aquatic Exposure Modeling .......................................................................................... 3 

b. Aquatic Exposure Monitoring and Field Data ................................................................... 3 

3. Measures of Terrestrial Exposure ......................................................................................... 3C, 

a. Terrestrial Exposure Modeling ......................................................................................& 

C. Ecological Effects Characterization ........................................................................................... .38 - 1. Aquatic Effects Characterization .......................................................................................... - 38 

a. Aquatic Animals ........................................................................................................ .s 

b. Aquatic Plants .......................................................................................................... ..a 

2. Terrestrial Effects Characterization.. ........................................................................... .B 

a. Terrestrial Animals.. ........................................................................................ ..44 - 

b. Terrestrial Plants ........................................................................................................ -48 -

IV. RISK CHARACTERIZATION ....................................................................................................... tjl 

A. Risk Estimation - Integration of Exposure and Effects Data ............................................................. tjl 

1. Non-target Aquatic Animals and Plants ................................................................................. a. Fish and Invertebrates .................................................................................................. 2 

b. Aquatic Plants ............................................................................................................ a 

2. Non-target Terrestrial Animals ............................................................................................. a 

a. Birds.. ...................................................................................................................... .s 

b. Mammals.. ................................................................................................................ .s 

c. Non-Target Terrestrial-phase Amphibians, Reptiles and Beneficial Invertebrates ..................... 3 

3. Non-target Terrestrial Plants in Terrestrial and Semi-aquatic Environments .................................. 2 

B. Risk Description .................................................................................................................... .& 

1. Risks to Aquatic Organisms ................................................................................................ -56 

a. Animals ..................................................................................................................... 5(' 

b. Aquatic Plants ........................................................................................................... .s 
2. Risks to Terrestrial Organisms ............................................................................................. a. Animals.. ................................................................................................................... j') 

b. Terrestrial Plants ........................................................................................................@ 

3. Spray Drift Analysis .......................................................................................................... -64 

4. Review of Incident Data ..................................................................................................... -67 

5. EndocrineEffects .............................................................................................................. 6. Federally Threatened and Endangered (Listed Species Concerns.. ........................................ ..68 - a. Action Area .............................................................................................................. .M 

b. Taxonomic Groups Potentially at Risk ............................................................................. a 

c. Indirect Effects Analysis ............................................................................................... 22 

d. Critical Habitat ........................................................................................................... a 

e. Co-occurrence Analysis ............................................................................................... .73 - 

C. Description of Assumptions, Limitations, Uncertainties, Strengths, and Data Gaps .............................. - 76 

1. Uncertainties, assumptions, and limitations associated with models ............................................. E 

2. Uncertainties, assumptions, and limitation associated with exposure scenarios .............................. - 78 

3. Uncertainties, assumptions, and limitation associated with the toxicity data .................................. 4. Uncertainties and assumptions associated with gaps in environmental fate and toxicity data ........... .(O 

V. Literature Cited ............................................................................................................................ .E 

Appendix A. Propazine 4L Label ......................................................................................................... ..u 

Appendix B. Environmental Fate Studies ................................................................................................. Appendix C. Aquatic Exposure Model and Results ................................................................................... - 93 

Appendix D. T-REX Model and Results ............................................................................................... 102 

Appendix E. TerrPlant Model and Results .............................................................................................. Appendix F. Ecological Effects Data .................................................................................................... Appendix G. The Risk Quotient Method and Levels of Concern.. .......................................................... 122 

Appendix H. Data Requirements .......................................................................................................... - 1'5 

Appendix I. Environmental Fate Bibliography ........................................................................................ - 129 

Appendix J. Ecological Toxicity Bibliography ........................................................................................ - 13 1 
LIST OF TABLES 

Table I-B 1 . Summary of Environmental Risk Conclusions for Aquatic Animals and Plants ........................... 8 

Table I-B 2 . Summary of Environmental Risk Conclusions for Terrestrial Animals and Plants ........................ 8 

Table I-B 3 . Listed Species Risks Associated with Direct or Indirect Effects ............................................. 9 

Table I-E 1 . Environmental Fate Data Requirements for Propazine ........................................................ 13 

Table I-E 2 . Ecological Effects Toxicity Data Requirements for Propazine .............................................. 14 

Table 11-A 1 . Physical and Chemical Properties of Propazine ................................................................................... 16 

Table 11-A 2 . Use Information for Propazine 4L (43% a.i.) ....................................................................................... 17 

Table 11-E 1 . Assessment Endpoints and Measures of Ecological Effects and Exposure ................................ 25 

Table 111-B 1 . Physicochemical and Fate Properties of Propazine .......................................................... 29 

Table 111-B 2 . PRZMiEXAMS Input Parameters for Propazine ............................................................................... 35 

Table 111-B 3 . Estimated Environmental Concentrations (pg/L) of Propazine in Surface Water .............................. 36 

Table 111-B 4 . Terrestrial Bird and Mammal EEC's (Residues) Following Application of Propazine to Sorghum ... 37 

Table 111-B 5 . EECs for Terrestrial Plants Located Adjacent to Propazine Treated Sorghum Fields ........................ 38 

Table 111-C 1 . Propazine Toxicity Endpoint Values for Assessing Risk to Aquatic Organisms ............................ 38 

Table 111-C 2 . Freshwater Invertebrate Acute Toxicity for Propazine ....................................................................... 39 

Table 111-C 3 . Freshwater Fish Chronic Toxicity for Propazine ............................................................................... 40 

Table 111-C 4 . Freshwater Invertebrate Chronic Toxicity for Propazine .................................................................... 40 

Table 111-C 5 . EstuarineIMarine Invertebrate Acute Toxicity for Propazine ....................................................... 41 

Table 111-C 6 . EstuarineiMarine Fish Chronic Toxicity for Propazine ...................................................................... 41 

Table 111-C 7 . EstuarineIMarine Invertebrate Chronic Toxicity for Propazine .......................................................... 42 

Table 111-C 8 . Non-Target Aquatic Plant Toxicity for Propazine .............................................................................. 42 

Table 111-C 9 . Non-Target Aquatic Plant Toxicity for the Degradate Deethylatrazine ........................................... 43 

Table 111-C 10 . Propazine Toxicity Endpoint Values for Assessing Risk to Terrestrial Organisms .......................... 43 

Table 111-C 11 . Avian Acute Oral Toxicity for Propazine ......................................................................................... 45 

Table 111-C 12 . Avian Acute Oral Toxicity for the Degradate Deethylatrazine .......................................................... 45 

Table 111-C 13 . Avian Subacute Dietary Studies for Propazine ................................................................................. 45 

Table 111-C 14 . Mammalian Acute Toxicity for Propazine ....................................................................................... 46 

Table 111-C 15 . Mammalian Acute Toxicity for the Degradate Deethylatrazine ..................................................... 46 

Table 111-C 16 . Mammalian DevelopmentaliReproductive Toxicity for Propazine .................................................. 47 

Table 111-C 17 . Mammalian Subchronic and Reproduction Toxicity for the Propazine Degradates ......................... 47 

Table 111-C 18 . Terrestrial Non-Target Plant Toxicity ............................................................................................... 50 

Table IV-A 1 . Toxicity Reference Values Used to Calculate Risk Quotients ........................................................... 51 

Table IV-A 2 . Summarized Acute Risks for Aquatic Organisms .............................................................................. 52 

Table IV-A 3 . Summarized Chronic Risks for Aquatic Organisms ........................................................................... 53 

Table IV-A 4 . Summarized Acute Aquatic Plant Risk Quotients ............................................................................. 53 

Table IV-A 5 . Mammalian Chronic Risk Quotient Summary ................................................................................... 54 

Table IV-A 6 . Terrestrial Plant Risk Quotient Summary for Terrestrial Spray Use on Sorghum ............................. 55 

Table IV-B 1 . Comparison of Peak EECs of Propazine in Surface Water to Aquatic Acute Toxicity Values .......... 57 

Table IV-B 2 . Comparison of 21- and 60-day EECs of Propazine in Surface Water to Aquatic Chronic Toxicity 

Values ................................................................................................................................. 58 

Table IV-B 3 . Comparison of Peak EECs of Propazine in Surface Water to Aquatic Plant Toxicity Values .......... 59 

Table IV-B 4 . Comparison of Avian Sublethal Values with Predicted Doses on Food Residues ............................. 61 

Table IV-B 5 . Mammalian Acute Risk Quotient Summary ....................................................................................... 61 

Table IV-B 6 . Comparison of Mammalian Chronic Toxicity Values with Predicted Doses on Food Residues ........ 63 

Table IV-B 7 . Agdrift Input Parameters for Terrestrial Plant Measurement Endpoints ................................ 65 

Table IV-B 8 . Summary of AgDRIFT Modeling Results for Endangered Plant Species ................................. 66 

Table IV-B 9 . Summary of AgDRIFT Modeling Results for Non-Endangered Plant Species ........................... 66 

Table IV-B 10 . Listed Species Risks Associated with Direct or Indirect Effects ........................................... 70 

Table IV-B 1 1 . Summarized Data from Locates .............................................................................. 75 
LIST OF FIGURES 

Figure 11-A1 . Sorghum growing areas in the US (USDA, 2003 data). ..................................................................... 15 

Figure 11-Dl . Ecological Risk Assessment Conceptual Model for Propazine ........................................................ 22 
I. EXECUTIVE SUMMARY 

A. Nature of Chemical Stressor 

The Environmental Fate and Effects Division (EFED) has reviewed the proposed new use 

of propazine (2-chloro-4,6-bis(isopropy1amino)-s-triazine) for weed control in sorghum 

(grain and sweet). Propazine is part of the triazine herbicide family (such as atrazine, 

cyanazine, simazine) and is very effective at stopping the photosynthetic process in 

susceptible plants by binding to specific sites within the plant's chloroplasts. Propazine is 

currently registered for use on container grown ornamentals in greenhouses (Propazine 

4L; EPA Reg. No. 18 12-352). Propazine is formulated as flowable concentrate and 

proposed applications are via ground or aerial equipment. 

For the 1993, 1994, 1995, 1996, and 1997 use seasons, at the request of sorghum 

growers, EPA granted section 18 emergency exemptions for the use of propazine in the 

five states of highest sorghum use: Colorado, Kansas, New Mexico, Oklahoma, and 

Texas Environmental fate studies indicate that propazine is moderately persistent and 

mobile. When applied in an outdoor environment, propazine has a high potential to leach 

into ground water or reach surface waters by runoff. In areas where the soils are highly 

permeable, the water table is shallow, and sufficient precipitation and/or irrigation occur, 

the use of propazine may result in surface and ground water contamination. In addition, 

the use of propazine on sorghum as specified on the proposed label prohibits use on sand, 

loamy sand, heavy clay, and high organic matter soils. As such, the risk conclusions 

contained in this assessment would not apply to these soil types. 

B. Potential Risks to Non-target Organisms 

This screening risk assessment indicates that at the maximum proposed propazine 

application rate for sorghum, the chronic Level of Concern (LOC) for freshwater 

invertebrates inhabiting surface waters adjacent to a propazine treated field is exceeded 

and these organisms may be at risk for adverse chronic effects on survival and growth 

when exposed to propazine in surface runoff andlor leachate as a result of spray 

application. Based on the available data, low risks are anticipated for freshwater and 

marinelestuarine invertebrates following acute exposure and to freshwater and 

marinelestuarine fish and marinelestuarine invertebrates following chronic exposure. 

Potential risk to freshwater and marinelestuarine fish following acute exposure could not 

be estimated due to lack of valid toxicity data. Lack of toxicity data do not rule out the 

possibility of risk to fish following acute exposure. 

There are exceedances of the LOCs for endangered vascular and non-vascular aquatic 

plants for runoffldrifl from ground and aerial spray applications of propazine to sorghum. 

However, there are no exceedances of LOCs for unlisted vascular aquatic plants. There 

are exceedances of LOCs for unlisted non-vascular aquatic plants, assuming that the 

maximum predicted propazine concentrations would come in contact with freshwater 

non-vascular plants. Consequently, endangered vascular and non-vascular plants and 

non-endangered non-vascular plants inhabiting surface waters adjacent to a treated field 

would be at risk for adverse effects to growth and development when exposed to 

propazine as a result of the proposed labeled use on sorghum. Although there are 
currently no listed non-vascular plants, there is concern for indirect effects on organisms 

dependent upon non-vascular plants for survival. 

Acute avian risk quotients (RQs) were not calculated because the results of the toxicity 

studies indicate that the acute LD5() and LC5o are greater than highest dose/concentration 

tested with no mortalities. A qualitative assessment was conducted comparing the 

estimated Environmental Exposure Concentrations (EECs) with the highest 

dose/concentration tested in each study. The highest EECs ranged from 4-fold lower to 

more than an order of magnitude lower than the highest dose/concentration tested in the 

acute oral and dietary avian studies. Therefore, the acute risk of mortality to birds, 

reptiles and terrestrial-phase amphibians is low. There is, however, a concern for acute 

sublethal effects (weight loss) as these effects are observed at anticipated EECs. No 

chronic avian toxicity data are available; therefore, no risks were estimated. Lack of 

toxicity data do not rule out the possibility of risk to birds, reptiles and terrestrial-phase 

amphibians following chronic exposure. The observed sublethal effects in birds 

following acute exposure and the observed effects in mammals following chronic 

exposure increase the uncertainty over the potential risk to birds, reptiles and terrestrialphase amphibians following chronic exposure. 

The chronic LOC is exceeded for all weight classes of mammals consuming short 

grasses, tall grasses, and broadleaf foragelsmall insects at both the maximum and mean 

predicted residue levels; and for 15 and 35 g mammals consuming hit and large insects 

at the maximum predicted residue levels. Consequently, mammals would be at risk for 

effects on reproduction and/or growth following chronic exposure to propazine with the 

proposed labeled use. As with birds, acute mammalian risk quotients (RQs) were not 

calculated because the results of the toxicity study indicated that the acute LD5() is greater 

than highest dose tested. A qualitative assessment, comparing the estimated 

Environmental Exposure Concentrations (EECs) with the highest dose tested indicates 

that there is no concern for acute risk to mammals because the EECs are less than an 

order of magnitude of the highest dose tested in the acute mammalian study. 

For the aerial spray application of propazine and the maximum application rate, the acute 

LOC was exceeded for nonendangered monocots and dicots located in adjacent areas and 

in semi-aquatic areas primarily as a result of runoff; and for both nonendangered 

monocots and dicots as a result of spray drift. Likewise, the acute LOC was exceeded for 

nonendangered monocots in semi-aquatic areas and nonendangered dicots in adjacent and 

semi-aquatic areas as the result of runoff from ground spray applications. For both 

ground and aerial spray application, the LOC was exceeded for endangered monocots and 

dicots located in adjacent and semi-aquatic areas primarily as a result of runoff. The 

LOC for endangered species was also exceeded for monocots and dicots in dry areas 

exposed to spray drift from aerial applications. Consequently, nonendangered and 

endangered monocots and dicots inhabiting dry and semi-aquatic areas adjacent to a 

treated field would be at risk for adverse effects to growth and development following 

exposure to propazine with the proposed labeled use. 

Tables I-B1 and I-B2 summarize the environmental risk conclusions for aquatic and 

terrestrial animals and plants. 
animals and plants 

Summarized Risk Characterization and 

Important Uncertainties 

No valid acute toxicity data are available. 

Lack of data does not rule out potential risk. 

Chronic LOCs are not exceeded for any of the 

proposed uses. 

LCSo > highest concentration tested (HCT). 

Highest peak aquatic EEC 61 times lower 

than HCT for this use; therefore, concern for 

acute risk to freshwater invertebrates is low. 

Application rate for Texas scenario needs to 

be reduced by 46% to 0.65 lb ai/A for the 

chronic LOC not to be exceeded. For Kansas 

scenario, rate needs to be reduced by 5% for 

chronic LOC not to be exceeded. 

No valid acute toxicity data are available. 

Lack of data does not rule out potential risk. 

Chronic LOCs are not exceeded for any of the 

proposed uses. 

Acute LOCs are not exceeded for any of the 

proposed uses. 

Chronic LOCs are not exceeded for any of the 

proposed uses. 

Although no listed non-vascular plants, there 

is still a concern for indirect effects on 

organisms dependent upon non-vascular 

plants for food and shelter. Application rates 

need to be reduced by 93% for the LOC for 

aquatic plants not to be exceeded. 

Table I-B2. Summary of environmental risk conclusions for terrestrial animals and plants 

risk conclusions for aquatic 

Use Patterns with LOC 

Exceedances 

Unknown 

None 

Chronic LOC exceeded for 

both Kansas (aerial) and 

Texas (aerial and ground) 

scenarios (1.2 lbs aiIA, 1 

applicatiodyear). 

Unknown 

None 

None 

None 

Acute endangered species 

exceeded for aquatic 

non-vascular and vascular 

plants for Texas and 

Kansas sorghum scenarios 

(1.2 lbs ai/A, 1 

applicatiodyear). 

Table I-B1. Summary 

Taxa 

Freshwater Fish 

and Aquatic 

Phase 

Amphibians 

Freshwater 

Invertebrates 

Marine1 

Estuarine Fish 

Marine1 

Estuarine 

Invertebrates 

Aquatic Plants 

- 

of environmental 

Assessment 

Endpoint 

Acute Risk 

Chronic 

Risk 

Acute Risk 

Chronic 

Risk 

Acute Risk 

Chronic 

Risk 

Acute Risk 

Chronic 

Risk 

Acute Risk 

Summarized Risk Characterization and 

Important Uncertainties 

Avian RQs not calculated; acute and 

LCso > highest dose/concentration tested with 

no mortalities. Highest EECs range from 4- 

fold to an order of magnitude less than 

highest doselconcentration tested. Therefore, 

acute risk of mortalities is low. Sublethal 

effects (weight loss) may occur at anticipated 

EECs. 

No chronic avian toxicity data available; 

sublethal effects in birds following acute 

exposure and observed effects in mammals 

following chronic exposure increase the 

uncertainty over the potential risk to birds, 

reptiles and terrestrial-phase amphibians 

Taxa 

Birds, Reptiles 

and Terrestrial 

Phase 

Amphibians 

Assessment 

Endpoint 

Acute Risk 

Chronic 

Risk 

Use Patterns with LOC 

Exceedances 

None 

Unknown 
Table I-B3 summarizes the listed species at risk associated with either direct or indirect effects 

following application of propazine at the requested rates. 

Table I-B2. Summary 

Taxa 

Mammals 

Non-target 

Invertebrates 

Terrestrial Plants 

Concerns For Federally Listed as Endangered and/or Threatened Species 

of environmental 

Assessment 

Endpoint 

Acute Risk 

Chronic 

Risk 

A~~~~ ~i~k 

Acute Risk 

Table I-B3. Listed species risks associated with direct or indirect effects due to applications of propazine on 

risk conclusions for 

Use Patterns with LOC 

Exceedances 

None 

Chronic LOC exceeded for 

1.2 lbs ailA, 1 

application/year with both 

Kansas and Texas 

scenarios. 

Not quantitatively assessed. 

Acute exceeded for 

nonendangered monocots 

and dicots .2 Ibs ailA, 

applicatiodyear. 

sorghum 

Listed Taxon 

Terrestrial and semi-aquatic plants - monocots 

Terrestrial and semi-aquatic plants - dicots 

Terrestrial invertebrates 

Birds 

Terrestrial-phase amphibians 

Reptiles 

terrestrial animals and plants 

Summarized Risk Characterization and 

Important Uncertainties 

following chronic exposure. 

Mammalian RQs not calculated; acute LD50 > 

HDT. Highest EEC an order of magnitude 

less than the HDT. Therefore, acute risk of 

mortalities is low. 

Chronic LOC exceeded for all weight classes 

of mammals consuming short grasses, tall 

grasses, and broadleaf foragelsmall insects; 

15 and 35 g mammals consuming fruit and 

large insects. 

Propazine is relatively non-toxic with a 96-hr. 

mortality rate of 2.47% at a dose of 96.69 

pghee. Acute risks to terrestrial insects 

likely to be low. 

Acute LOC exceeded for nonendangered 

monocots and dicots for both ground and 

aerial spray application (1.2 lbs aiIA, 1 

applicationlyear). Nonendangered and 

endangered monocots and dicots inhabiting 

dry and semi-aquatic areas adjacent to a 

treated field at risk. 

Direct Effects 

Yes 

Yes 

No for terrestrial insects; 

unknown for other terrestrial 

invertabrates (insufficient data) 

Possible: no chronic avian data; 

sublethal effects in acute studies 

coupled with similar effects in 

mammalian reproduction study 

increase uncertainty for birds. 

Possible: no acute or chronic 

data and no chronic avian data 

(see comment for birds) 

Possible: no acute or chronic 

Indirect Effects 

Yes through effects to pollinators 

(mammals; uncertain with birds, 

reptiles, terrestrial-phase 

amphibians) 

Yes through effects to pollinators 

(mammals; uncertain with birds, 

reptiles, terrestrial-phase 

amphibians) 

Yes through effects to terrestrial 

and aquatic plants (food and 

habitat) 

Yes through effects to terrestrial 

and aquatic plants (food and 

habitat), mammals, freshwater 

invertebrates) 

Yes through effects to terrestrial 

and aquatic plants (food and 

habitat), mammals, freshwater 

invertebrates) 

Yes through effects to terrestrial 
I Table I-B3. Listed species risks associated with direct or indirect effects due to applications of propazine on I 

Listed Taxon Indirect Effects 

habitat), mammals, freshwater 

invertebrates) 

and aquatic plants, mammals, 

Direct Effects 

data and no chronic avian data 

(see comment for birds) 

Mammals Yes with chronic exposure. 

Aquatic non-vascular plants* 

Aquatic vascular plants 

Freshwater fish 

Aquatic-phase amphibians 

Freshwater crustaceans 

Mollusks 

Yes 

Yes 

Unknown with acute exposure 

(no acute data); No after chronic 

exposure. 

Unknown with acute exposure 

(no acute data); using chronic 

data on fish as surrogate - No 

after chronic exposure. 

Using data on daphnia as 

surrogate - No after acute 

exposure and Yes after chronic 

exvosure. 

Marinelestuarine fish 

freshwater invertebrates. 

No 

No 

Yes through effects to terrestrial 

plants (stream quality), aquatic 

plants (food and habitat) and 

freshwater invertebrates (food) 

Yes through effects to terrestrial 

plants (stream quality), aquatic 

plants (food and habitat) and 

freshwater invertebrates (food) 

Yes through effects to terrestrial 

plants (stream quality), aquatic 

plants (food and habitat) and 

other freshwater invertebrates 

No after acute exposure; Using 

chronic data on crustaceans as 

surrogate - NO after chronic 

Marinelestuarine crustaceans 

As noted above, propazine may not be applied to selected soils and as such the risk conclusions 

do not apply to locations where sorghum is grown on these soils. More details on the risk 

conclusions can be found in the Executive Summary of the Ecological Risk Science Chapter for 

propazine. 

(food). 

Yes through effects to terrestrial 

plants (stream quality) and 

aquatic plants (food and habitat). 

exposure. 

Unknown: no acute data 

No after chronic exposure. 

L 

C. Conclusions - Exposure Characterization 

Yes through effects to terrestrial 

plants (tributarylestuary quality) 

and aquatic plants (food and 

No after acute andlor chronic 

exposure. 

invertebrates (food). 

Propazine, like the other triazine chemicals, is weakly basic (pKa = 1.85 at 22OC), can be 

easily protonated at low soil pH values, and is likely to exist as a neutral species at soil 

pH values more than two pH units above the pKa. Adsorption of protonated propazine is 

pH-dependent, with a maximum adsorption at or near the pKa. Soil organic matter plays 

an important role in the adsorption of propazine and other s-triazines, affecting their 

movement in soil. 

habitat) 

Yes through effects to terrestrial 

plants (tributarylestuary quality), 

aquatic plants (food and habitat) 

and other marinelestuarine 

* At the present time no aquatic non-vascular plants are included in Federal listings of threatened and endangered species. The 

taxono~nic group is included here for the purposes of evaluating potential contributions to indirect effects to other taxa and as a 

record of exceedences should future listings of non-vascular aquatic plants warrant additional evaluation of Federal actions. 
The herbicide propazine is expected to be persistent and mobile in most soils, and it is 

resistant to breakdown by hydrolysis, photolysis, or biodegradation. Propazine does not 

adsorb as strongly to soil particles as other triazine herbicides. In most soils used in 

batch equilibrium studies, especially sand and sandy loam soils, it binds weakly to soil 

particles. Likewise, studies have shown that depending on soil temperature, moisture, 

and pH, it can become unbound. It is therefore very likely that in areas where soils are 

highly permeable, the water table is shallow, or where there is irrigation and/or high 

rainfall, the use of propazine may result in ground water contamination. 

Routes of aquatic exposure evaluated in this screening risk assessment focused on 

deposition, runoff and spray drift from aerial and ground applications of propazine. The 

propazine exposure characterization, combined the environmental fate data with the Tier 

I1 models Pesticide Root Zone Model (PRZM) version 3.12beta and Exposure Analysis 

Modeling System (EXAMS) version 2.98 linked to simulate the transport of the pesticide 

off the field, and to estimate EECs in a standard pond based on the propazine aerial and 

ground applications at the proposed maximum application rate for sorghum (1.2 lb 

a. i ./acre). 

Routes of exposure for the terrestrial assessment of birds and mammals were developed 

using the T-REX (Ver.1.2.3) model to estimate propazine residues on food types as the 

result of application to sorghum. Likewise, EECs for non-target terrestrial plants were 

estimated for broadcast spray application using the TerrPlant (Ver 1 .O) model in 

conjunction with AgDrifi (Ver. 2.0.1). AgDrifi provides further refinement of spray drift 

dispersion and deposition to plants located in proximity to treated fields or treated water 

bodies. There were no reported incidents from propazine use recorded in the Ecological 

Incident Information System (EIIS) as of June 2006. 

D. Conclusions - Effects Characterization 

The submitted acute toxicity study with a freshwater invertebrate (daphnid) provides a 

48-hr EC50 value of >5.32 pprn ai (NOAEC 5.32 pprn ai, highest concentration tested) for 

the TGAI. No valid acute freshwater fish studies are available for propazine. 

For freshwater fish (early life-stage or a full life-cycle test), propazine induced a 

significant reduction in length in fathead minnows with a NOAEC of 0.72 mg ai/L. 

Likewise, propazine induced reductions in growth (length and weight) in daphnids with a 

NOAEC of 0.047 pprn ai. 

Propazine is categorized as moderately toxic to the mysid shrimp, based on mortality and 

sublethal effects (LC50 = 4.20 pprn ai). Propazine is categorized as practically non-toxic 

to the eastern oyster at the limit of solubility with an EC50 >3.72 mg ai/L. In an early 

life-stage study with sheepshead minnow, propazine affected embryo survival and 

hatching success at 2.59 mg ai/L with a NOAEC of 1.34 mg ai/L. This study was used to 

assess the chronic risk of propazine to estuarine/marine fish. For the life-cycle toxicity 

study with estuarinelmarine invertebrates, propazine induced significant effects to growth 

and reproduction at 0.706 pprn ai in mysid shrimp with a NOAEC of 0.269 pprn ai. No 
toxicity studies were submitted by the registrant to assess the acute risk of propazine to 

estuarinelmarine fish species. 

Aquatic plant toxicity studies with propazine provide an ECso of 0.10 ppm ai for 

freshwater vascular plants (duckweed) with a NOAEC of 0.022 ppm ai, based on frond 

density. The lowest ECjo for freshwater non-vascular plants (diatom) is 0.0248 ppm ai 

with a NOAEC of 0.0065 ppm ai, based on cell density. 

Available acute toxicity data indicate propazine is at most, slightly toxic to birds. The 

upland gamebird acute oral LDso value was >1,640 mg aikg. There were no mortalities. 

A NOAEL was determined to be 244 mg ailkg based on weight loss. The acute dietary 

LCjos were >4,930 ppm and >5,140 for bobwhite quail and mallard, respectively. No 

avian reproduction studies were submitted by the registrant. 

Propazine is categorized as practically non-toxic to small mammals on an acute oral basis 

(LD5O value >5,050 mg/kg). In a 3-generation reproduction study with rats, no treatmentrelated effects on reproduction were observed; consequently, the NOAEL for 

reproductive toxicity was 250 mg/kg bwlday, the highest dose tested. The 

parentalloffspring NOAEL was 5 mgkg/day based on decreased body weights in both 

sexes. 

Terrestrial plant toxicity studies with monocots and dicots indicate that seedling 

emergence and vegetative vigor are severely impacted by exposure to propazine. 

Seedling emergence, based on shoot weight, was adversely impacted in monocots (onion) 

at an EC2s of 0.035 lb ai/A and in dicots (lettuce) with an EC25 of 0.016 Ib ai1A. 

Vegetative vigor in monocots, based on shoot weight, was adversely impacted in 

monocots (wheat) at an EC2j of 0.046 Ib ai/A and in dicots (cucumber) at an EC25 of 0.10 

lb ai1A. The observed effects to monocots and dicots included stunting, chlorosis, 

necrosis, and plant death. 

E. Uncertainties and Data Gaps 

There are a number of areas of uncertainty in the terrestrial and the aquatic organism risk 

assessment that could potentially cause an underestimation of risk. First, this assessment 

accounts only for exposure of non-target organisms to propazine, but not to its 

degradation products. The risks presented in this assessment could be underestimated if 

degradates also exhibit toxicity under the conditions of use as stated on the label as 

limited data are available concerning the toxicity of the degradates. Second, the risk 

assessment only considers the most sensitive species tested from a limited set of toxicity 

studies conducted with relatively few species and only considers a subset of possible use 

scenarios. For the aquatic organism risk assessment, there are uncertainties associated 

with the PRZMIEXAMS models, input values, and the use of surrogate scenarios. The 

potential impacts of these uncertainties are outlined in the Aquatic Exposure, the 

Terrestrial Exposure and the Risk Characterization sections of this document. 

Additional uncertainty results from the lack of information and/or data in several 

components of this ecological risk assessment, as follows. 
Acute risks for freshwater fish were not characterized because the submitted study 

was determined to be invalid based on solubility issues. A high degree of 

uncertainty exists for the freshwater toxicity data for propazine until it can be 

shown that the results reflect that the tests were conducted up to the limit of 

solubility or provide a definitive median lethal concentration. An acceptable 

study will improve the certainty of the ecological risk assessment. 

Chronic risk to avian species was not characterized because no studies with the 

TGAI were submitted. Sublethal effects in the acute avian studies coupled with 

similar effects observed in the mammalian reproduction study increase the 

uncertainty of effects in birds following chronic exposure. 

Current data are not available to assess potential risk of propazine degradates to 

aquatic fish and invertebrates and terrestrial plants. 

Fate studies indicate propazine is persistent and mobile raising concerns about the 

impact on groundwater and surface water. The field dissipation studies that have 

been submitted are considered unacceptable or supplemental resulting in a 

significant uncertainty for this transport pathway. To address this uncertainty, 

studies are needed to comprehensively ascertain the mobility of propazine and its 

degradates under field conditions. 

No aerobic or anaerobic aquatic metabolism studies are available for use in this 

assessment. Therefore, EFED has made an assumption that propazine is two 

times as persistent in aerobic aquatic environments as it is in aerobic soil. Data on 

the aquatic metabolism of propazine will be needed to address this uncertainty. 

Tables I-El and I-E2 summarize the environmental fate and ecological toxicity 

data gaps for propazine and the value of additional testing. 

Terrestrial Field 
(rainbow trout) 

(bluegill sunfish) class indicate that LCs0 is likely sufficiently high not to exceed acute LOC 

72-2 

72-3a 

72-4a 

72-4d 

Freshwater invertebrate acute ECSo 

(daphnia) 

Estuarineimarine fish acute LCjo 

(sheepshead minnow) 

Freshwater fish early life stage 

(fathead minnow) 

Estuarineimarine invertebrate life 

cycle (mysid) 

for endangered species. 

Pending. A study has been reviewed but not finalized by the Agency 

(MRID 442873-05). The study is scientifically sound but does not fulfill 

guideline requirements because daphnids were not exposed up to 100 ppm 

ai. Consequently, the acute toxicity of propazine to freshwater invertebrates 

cannot be categorized. If it can be shown that the test was conducted up to 

the limit of solubility, the study could be upgraded to acceptable. However, 

for these requested uses, a comparison of the highest concentration tested in 

the daphnid study with the peak EEC for the proposed uses shows that there 

were no effects in daphnids at concentrations 61 times higher than the 

highest peak EEC. 

Medium. No studies available. Chronic toxicity NOAECILOAEC from 

sheepshead minnow study plus a comparison with chemicals from similar 

class indicate that LCjo is likely sufficiently high not to exceed acute LOC 

for endangered species. 

Low. The study was classified as supple~nental because pH and hardness 

exceeded recommended levels, potentially affecting solubility. 

Low. The study was classified as supplemental due to deviations in study 

design. 
11. PROBLEM FORMULATION 

A. Stressor Source and Distribution 

1. Source and Intensity 

Figure 11-A1. Sorghum growing areas in the US (USDA, 2003 data). 

The proposed use of propazine (2-chloro-4,6-bis(isopropylamino)-s-triazine) is for weed 

control in sorghum (grain and sweet). The proposed label allows one application per 

crop cycle (growing season) with the maximum application rate for sorghum of 1.2 Ib 

ailacre (A). Figure I1.a. 1. depicts areas in the US where sorghum was grown and 

harvested in 2003 thus providing an indication of likely propazine use areas. Potential 

use areas are indicated in the Midwest states of Colorado, New Mexico, Kansas, 

Nebraska, Oklahoma, Texas and South Dakota, southern regions of Arizona and 

California, along the Mississippi river valley and along the eastern coastal regions of 

North Carolina and Maryland. Propazine is currently registered for use on container 

grown ornamentals in greenhouses (Propazine 4L; EPA Reg. No. 1812-352). 

2. PhysicaVChemicaVFate and Transport Properties 

Propazine is a colorless crystalline solid. It is stable in neutral, slightly acid, or alkaline 

media, but is hydrolyzed by stronger acids and alkalis. It is nonflammable and non 

corrosive under normal use conditions, however may bum if exposed to heat or flame. 

Thermal decomposition may produce toxic oxides of carbon and nitrogen, and toxic and 
corrosive fumes of chlorides. Table 11-A1 provides a summary of some properties for 

propazine. 

Propazine is expected to be moderately persistent and mobile in most soils, and it is 

resistant to breakdown by hydrolysis, photolysis, or biodegradation. Batch equilibrium 

experiments suggest that propazine is mobile, with Freundlich Kd values ranging from 

0.67 to 3.19 in two separate studies involving 8 soil textures. The LC values ranged from 

65 to 268 in these same studies. The mobility of propazine is also noted in the 

supplemental terrestrial field dissipation studies suggesting that propazine dissipates 

slowly from the upper 6 inches (half-lives of 5 1 days in TX, and 7 to 58 days in NC, <30 

to 149 days in NY, <3 1 days in CA, and 60 to >357 days in NE) and may leach to ground 

water. It has also been reported in the literature that if released to soil, propazine will 

persist longer in dry or cold conditions or other conditions which inhibit biological and 

chemical activity (Worthing, C.R., ed., 1983. "The pesticide manual: A world 

compendium. Croydon, England: The British Crop Protection Council"). Therefore, it is 

very likely that the use of propazine may result in groundwater and/or surface water 

contamination in areas where soils are highly permeable, the water table is shallow, or 

where there is irrigation and/or high rainfall. Volatility and air photolysis are not 

expected to be major routes of dissipation due to the low vapor pressure (2.9 x 10'~ torr at 

20°C). 

Common name: Propazine 

Chemical name: 2-chloro-4,6-bis(isopropy1amino)-s-triazine 

CAS number: 139-40-2 

Trade names: Propazine 4L 

3. Pesticide Type, Class and Mode of Action 

Propazine is part of the triazine herbicide family (such as atrazine, cyanazine, simazine) 

and is very effective at stopping the photosynthetic process in susceptible plants by 

binding to specific sites within the plant's chloroplasts. The mode of action is inhibition 

of photosynthesis by stopping electron flow in Photosystem 11, which in turn inhibits the 
formation and release of oxygen. Currently, Griffin L.L.C. is seeking registration for 

propazine as a selective herbicide for control of weeds in sorghum. 

4. Overview of Pesticide Usage 

Propazine has been previously registered for use on sorghum and in greenhouse 

ornamentals. However, due to economic considerations, in 1990, the propazine 

registration for sorghum was voluntarily cancelled by the Registrant (then Ciba-Geigy). 

For the 1993,1994,1995,1996, and 1997 use seasons, at the request of sorghum 

growers, EPA granted section 18 emergency exemptions for the use of propazine to the 

five states of highest sorghum use: Colorado, Kansas, New Mexico, Oklahoma, and 

Texas. Currently, propazine is only registered for use on container grown ornamentals in 

greenhouses. 

Propazine is proposed for use as a selective herbicide in sorghum before planting, at 

planting and after crop (sorghum) emergence for control of many annual broadleaf weeds 

such as pigweed, devil's claw, carpetweed, smartweed, kochia, morningglory, ragweed, 

velvetleaf and others. Application can be made via ground sprayer or aerial broadcast for 

sorghum. End use formulations of propazine that are manufactured by Griffin L.L.C. 

include a 98% wettable powder technical product and a 43% flowable concentrate end 

use product (Propazine 4L). Table 11-A2 lists the food and non-food uses (based on 

application and use rates) for propazine according to the proposed label information. 

In addition, the use of propazine on sorghum as specified on the proposed label prohibits 

use on sand, loamy sand, heavy clay, and high organic matter soils. As such, the risk 

conclusions contained in this assessment would not apply to these soil types. 

Table 11-A2. Use Information for Propazine 4L (43% a.i.) 

B. Receptors 

Crop (Application type) 

Container-grown ornamentals in 

greenhouses (ground) 

Sorghum -Grain and Sweet 

(ground and aerial) 

For the screening level risk assessment on propazine, toxicological data generated on 

representative test species belonging to broad taxonomic groups are summarized, then 

utilized in an assessment of risk for each group. These data are obtained from registrantsubmitted studies. Table 11-El in the Analysis Plan section provides the taxonomic 

groups and surrogate test species evaluated for ecological effects in the screening-level 

risk assessment for propazine. Within each of these very broad taxonomic groups, an 

acute and/or chronic measure of effect is selected from the available test data. A 

Soil Texture 

Sand, Loamy Sand, and Sandy Loam 

Loam, Silt, Silty Loam, Silty Clay Loam, and 

Sandy Clay Loam 

Sandy Clay, Clay Loam, Silty Clay Loam, and 

Peat-Lite Mixes 

Sand, Loamy Sand, Heavy Clay, High OM 

Sandy Loam, Loam, Silt Loam, and Clay Loam 

Rate 

0.01 17 lb ai/1000ft2 

0.0195 Ib ai/lOOOftL 

0.0352 Ib ai/1000ft2 

Do not use 

1.2 lb ailA 
complete discussion of all toxicity data available for this risk assessment for propazine 

and the resulting measurements of effect selected for each taxonomic group are included 

in Appendix F. 

1. Aquatic Effects 

Spray drift and runoff to adjacent bodies of water are the most likely sources of propazine 

exposure to nontarget aquatic organisms, including endangered and threatened species. 

In addition, the mobility of propazine in soils indicates that in areas where soils are 

highly permeable, the water table is shallow, or where there is irrigation and/or high 

rainfall; leaching to groundwater may occur, which may result in exposure to aquatic 

organisms where a potential hydrological connection to surface water bodies exists. 

Propazine is not expected to bioaccumulate in aquatic organisms or to adsorb to 

sediments; consequently risk to benthic-dwelling organisms should be minimal. 

For propazine, effects on aquatic organisms are estimated from acute and chronic 

laboratory studies submitted to the Agency by the registrant. The toxicity data for 

propazine will be used to assess risk to fish, aquatic invertebrates, and aquatic plants. 

Acute data are available for freshwater invertebrates [water flea (Daphnia magna)] and 

marinelestuarine invertebrates [eastern oyster (Crassostrea virginica) and saltwater 

mysid (Mysidopsis bahia)]. Reproductive or growth effects from chronic exposure are 

estimated from studies conducted with fish and invertebrates. For propazine, data are 

available to evaluate the chronic effects on freshwater fish and invertebrates and 

estuarine/marine fish and invertebrates. Toxicity data are available for aquatic vascular 

plants (duckweed, Lemna gibba); non-vascular algae (green algae, Selenastrum 

capricoi.nuturn; blue-green algae, Anabaenaflos-aquae); and freshwater and marine 

diatoms (Navicula pelliculosa, Skeletonema costatum). 

2. Terrestrial Effects 

Ground deposition from spray application and spray drift with resulting residues on 

foliage and on flowers and seeds are the most likely sources of propazine exposure to 

nontarget terrestrial organisms, including endangered and threatened species. Current 

data were not provided to determine the potential exposure to birds, mammals, and 

pollinators from residues on foliage, flowers, and seeds. The effect of acute exposure to 

propazine on all bird species is estimated from acute oral and dietary studies on either 

bobwhite quail (Colinus virginianus) and/or mallard duck (Anus platyrhynchos). These 

species also act as surrogates for reptiles and terrestrial-phase amphibians. Propazine 

acute oral toxicity effects data are available for the bobwhite quail only. Acute dietary 

toxicity data are available for both bobwhite quail and mallard duck. No toxicity studies 

have been conducted to determine the potential chronic effects to birds or the effect of 

residues to pollinators. 

Effects on mammals are estimated from acute and chronic laboratory studies reviewed by 

the Registration Division (RD) and Health Effects Division (HED), respectively. 

Propazine effects data for mammals are available for acute (rat) and chronic 

[(reproductive (rat) and developmental (rat and rabbit))] oral exposure. An additional 

source of exposure to propazine could be in puddled waters on treated fields through 
preening and grooming, involving the oral ingestion of material from the feathers or fur. 

Propazine is expected to be moderately persistent and mobile in most soils and is resistant 

to breakdown by hydrolysis, photolysis, or biodegradation. Consequently, exposure to 

birds, small mammals, and soil invertebrates through dermal contact or ingestion of soils 

could occur. Exposure to propazine via inhalation would be expected to be low due to its 

low vapor pressure. Currently, screening level assessments do not address exposure via 

the dermal and inhalation routes (see Assumptions, Limitations, Uncertainties, Strengths 

and Data Gaps section for further explanation). 

Spray drift presents a potential risk to non-target plants inhabiting edge habitats adjacent 

to target fields and riparian vegetation along streams and/or ponds in close proximity to 

sprayed fields. In addition, uptake in plant roots could occur through ground spray 

application. Studies (seedling emergence and vegetative vigor) were submitted to 

evaluate the effects of propazine to terrestrial monocots and dicots. 

3. Ecosystems at Risk 

The proposed uses of propazine could result in exposure to aquatic and terrestrial 

organisms inhabiting flowing, non-flowing or transient freshwater bodies and to 

wildlands (forests, wetlands and ecotones; such as edge and riparian habitats). For uses 

in coastal areas, aquatic habitats also include marine ecosystems, including estuaries. For 

both terrestrial and aquatic animal species, direct and indirect acute and chronic 

exposures are considered. For screening level assessment purposes, risk will be assessed 

to aquatic animals and plants assumed to occur in small, static ponds receiving runoff and 

drift from treated areas. Aquatic animal species of potential concern include freshwater 

fish and invertebrates, estuarinelmarine fish and invertebrates, and amphibians. Aquatic 

plant species of concern include vascular and non-vascular plants. 

The terrestrial ecosystems potentially at risk include the treated area and areas 

immediately adjacent to the treated area that might receive drift (wind dispersion) or 

runoff, and might include other cultivated fields, fence rows and hedgerows, meadows, 

fallow fields or grasslands, woodlands, riparian habitats, wetlands, and other uncultivated 

areas. For screening level assessment purposes, risk will be assessed to terrestrial 

animals assumed to exclusively occur in the treated area. Terrestrial animal species of 

potential concern include birds, mammals, beneficial invertebrates, and earthworms. 

Propazine is readily absorbed through the foliage and roots of plants; consequently, it 

could be injurious to non-target plant species by drift, runoff, or root and foliar uptake. 

Terrestrial plant species of concern include monocots, dicots, and semi-aquatic plant 

species. 

C. Assessment Endpoints 

The typical assessment endpoints for screening-level pesticide ecological risk 

assessments are reduced survival and reproductive and growth impairment for both 

terrestrial and aquatic animal species. For terrestrial and semi-aquatic plants, the 

screening assessment endpoint is the perpetuation of populations of non-target species. 

Existing testing requirements have the capacity to evaluate emergence of seedlings and 

vegetative vigor. Although it is recognized that these endpoints may not address all 
terrestrial and semi-aquatic plant life cycle components, it is assumed that impacts at 

emergence and in active growth have the potential to impact individual competitive 

ability and reproductive success. For aquatic plants, the assessment endpoint is the 

maintenance and growth of standing crop or biomass. Measures of effect for this 

assessment endpoint focus on algal and vascular plant growth rates and biomass 

measurements. 

This ecological risk assessment considers single application at the maximum propazine 

application rate to fields that have vulnerable soils to estimate exposure concentrations. 

This assessment is not intended to represent a site- or time-specific analysis. Instead, it is 

intended to represent high-end exposures at a national level. Likewise, the most sensitive 

toxicity endpoints are used from surrogate test species to estimate treatment-related direct 

effects on acute mortality and chronic reproductive, growth and survival assessment 

endpoints. Toxicity tests are intended to determine effects of pesticide exposure on birds, 

mammals, fish, terrestrial and aquatic invertebrates, and plants. These tests include shortterm acute, subacute, and reproduction studies and are typically arranged in a hierarchical 

or tiered system that progresses from basic laboratory tests to applied field studies. The 

toxicity studies are used to evaluate the potential of a pesticide to cause adverse effects, 

to determine whether further testing is required, and to determine the need for 

precautionary label statements to minimize the potential adverse effects to non-target 

animals and plants (CFR 40 9 158.202,2002). A summary of measurements of effect 

selected to characterize potential ecological risks associated with exposure to propazine 

are provided in Table 11-El in the Analysis Plan section. 

In order to protect threatened and endangered species, all assessment endpoints are 

measured at the individual level. Measuring endpoints at the individual level also 

provides insight about risks at higher levels of biological organization (e.g. populations 

and communities). For example, pesticide effects on individual survivorship have 

important implications for both population rates of increase and habitat carrying capacity. 

The ecological relevance of selecting the above-mentioned assessment endpoints is as 

follows: 1) complete exposure pathways exist for these receptors; 2) the receptors may be 

potentially sensitive to pesticides in affected media and in residues on plants, seeds, and 

insects; and 3) the receptors could potentially inhabit areas where pesticides are applied 

or areas where runoff andlor drift may impact the sites. 

D. Conceptual Model 

1. Risk Hypotheses 

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in 

assessment endpoints) and may be based on theory and logic, empirical data, 

mathematical models, or probability models (EPA, 1998). For this assessment, the risk is 

stressor-linked, where the stressor is the release of propazine to the environment. The 

following risk hypothesis is presumed for this screening level assessment: 

Based on the mobility and persistence ofpropazine, the mode of action, and the-food-web 

of the target aquatic and terrestrial ecosystems, propazine has the potential to cause 
reduced survival, and reproductive and growth impairment for both aquatic and 

tei*restrial animal and plant species. 

Adequate protection is defined as protection of growth, reproduction, and survival of 

aquatic and terrestrial ecological populations, and individuals of listed species, as needed. 

2. Diagram 

All potential routes of exposure are considered and are presented in the conceptual site 

model. The conceptual site model shown in Figure 11-Dl for ground and aerial spray 

applications generically depicts the potential source of propazine, release mechanisms, 

abiotic receiving media, biological receptor types, and effects endpoints of potential 

concern. 

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a 

contaminant moves in the environment from a source to an ecological receptor. For an 

ecological exposure 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. In addition, the potential mechanisms of transformation (i.e., 

which degradates may form in the environment, in which media, and how much) must be 

known, especially for a chemical whose metabolitesldegradates are of greater 

toxicological concern. The assessment of ecological exposure pathways, therefore, 

includes an examination of the source and potential migration pathways for constituents, 

and the determination of potential exposure routes (e.g., ingestion, inhalation, dermal 

absorption). 
Source: 

Exposure Media Residues 

I - - - - - - - - - - - 

Exposure I I I Dietary Uptake I Direct Ingestion Dietary Uptake Direct 

Ingestion 

Direct 

C 

*Plant growth abnormalities 

*Lethality 

Receptor 

\, Pollinators 

\ 

Non-Target 

Plants 

Terrestrial Animals: 

*Lethal and non-lethal effects 

*Reproductiveldevelopmental 

effects 

*Effects on foraging behavior 

I I 

Figure 11-Dl. Ecological Risk Assessment Conceptual Model for Propazine 

Aauatic Animals and Plants: 

*Effects to survival, growth, and 

reproduction 

*Reductions in cell density1 

biomass in aquatic plants 

I I I I 

Ter. Herbivores, 

Birds, 

Mammals, 

Altered Aquatic Community Assemblages: 

Effects to riparian habitat availability 

Effects to species abundancetdiversity 

Changes in ~hvsical/chemical parameters 

Altered Terrestrial Community Assemblages: 

Non-Target Plants 

(edge and riparian 

habitat) 

Indirect Reduced food supply and edge habitat availability 

Algae, Aquatic Vascular Plants, 

Aquatic Vertebrates, 

Aquatic Invertebrates 

Terrestrial 

Vertebrates & 

Invertebrates 
E. Analysis Plan 

The Agency's new use science chapter for propazine consists of a deterministic screening 

level risk quotient analysis. The aquatic and terrestrial assessments focus on the 

proposed agricultural use of propazine for weed control in sorghum with the highest 

application rate (1.2 lb ai/A) as specified by the current label (as of 8/01/05). Potential 

exposure pathways (i.e., runoff and spray drift) result from ground and aerial application 

of aqueous propazine formulations to sorghum. 

The Agency reviewed the available laboratory environmental fate data submitted in 

support of the proposed new use of propazine to determine propazine persistence and 

mobility. Based on this data, the Agency developed its quantitative aquatic assessment of 

propazine exposure using the PRZMIEXAMS model to represent potential propazine use 

areas. Likewise, terrestrial wildlife may be exposed to propazine through the plant or 

animal material that they contact or consume as food. For ground and aerial spray 

applications of propazine, exposure to terrestrial wildlife was estimated by relating food 

item residues to pesticide application using the Kenaga nomogram as modified by 

Fletcher (Hoerger and Kenaga, 1972; Fletcher et al., 1994). A computer model (T-REX, 

Version 1.2.3) was used to predict degradation of residues on foliar surfaces and insects. 

For mammals, the residue concentration was converted to a daily oral dose based on 

fractions of body weight consumed daily. Terrestrial non-target plant exposure 

characterization employed runoff and spray drift scenarios based on propazine use on 

sorghum and were estimated using OPP's TerrPlant model (Version 1 .O) as well as the 

AgDrift2.0.1 model to provide further refinement of spray drift dispersion and deposition 

to terrestrial plants located in proximity to treated fields. 

The most sensitive aquatic and terrestrial eco-toxicological values from studies submitted 

to the Agency were used in this quantitative assessment. Risks were estimated based on a 

deterministic approach, where a single point estimate of toxicity is divided by an 

exposure estimate to calculate a risk quotient (RQ). The acute and chronic RQ values for 

each taxonomic group identified as an assessment endpoint were compared to the 

Agency's Levels of Concern (LOCs). LOCs serve as criteria for categorizing potential 

risk to non-target organisms. RQ values were calculated in the risk estimation section for 

each endpoint, and characterization and interpretation of risk is described in the risk 

description. Risks for each taxonomic group were described based on available lines of 

evidence from registrant-submitted studies, open literature, and incident reports. In 

addition, a preliminary assessment of listed species of concern was also completed. 

No degradates were included in this assessment. One major degradate detected at > 10% 

of applied, hydroxyl-propazine (2-hydroxy-4,6-bis(isopropy1amino)-s-trine) was not 

included in this assessment due to the fact that it was determined to not be of 

toxicological concern in the assessments for atrazine and simazine and the fact that no 

environmental fate data was available. The minor degradates, desethylatrazine (2-amino4-chloro-6-isopropylamino-s-triazine or DEA) and 2,4-diamino-6 chloro-s-triazine 

(DACT), were not included in this assessment mostly due to their low detection in the 

laboratory soil metabolism studies and in the terrestrial field studies (less than 5% of 
Total Applied Radioactivity (TAR)). Laboratory and field studies indicate that DEA and 

DACT, if formed in the environment, would not be present nor would persist at any 

significant concentration compared to parent propazine to adversely impact the results of 

the ecological risk assessment. In addition, toxicity studies indicate that the degradates 

exhibit similar toxic responses in birds, mammals and aquatic plants as the parent 

propazine. 

Table 11-El summarizes the assessment endpoints and measures of ecological effects and 

exposure used in the ecological risk assessment for propazine. 
Table 11-El. Assessment Endpoints and Measures of Ecological Effects and Exposure for Propazine 

Taxonomic Group Assessment Endpoint Surrogate Species and Measures of Exposure 

Measures of Ecological Effect 

Reproduction and growth 

Mammals 

Freshwater fish 

Freshwater invertebrates 

Estuarinelrnarine fish 

Estuarinelmarine 

invertebrates 

Survival 

Reproduction and growth 

Survival 

Reproduction and growth 

Survival 

Reproduction and growth 

Survival 

Reproduction and growth 

Survival 

Reproduction and growth 

Laboratory rat acute oral LDJ0 

Laboratory rat oral reproduction 

chronic NOAEC and 

LOAEC 

Rainbow trout and bluegill 

sunfish acute LCso (no 

valid study available) 

Fathead minnow 

chronic (early life-stage) 

NOAEC and LOAEC 

Water flea (and other freshwater 

invertebrates) acute EC50 

Water flea (life 

LOAEC 

Sheepshead minnow acute LC5,) 

(no study available) 

Sheepshead 

(early life-stage) NOAEC 

and LOAEC 

Eastern oyster acute ECSo and 

mysid acute LC50 

chronic and 

LOAEC 

items (foliar) 

peak EEC 

60-day average EEC 

Peak EEC 

2 1-day average EEC 

peak EEC 

60-day average EEC 

peak EEC 

2 1-day average EEC 
I Table 11-El. Assessment Endpoints and Measures of Ecological Effects and Exposure for Propazine I 

Key Uncertainties and Information Gaps 

"Birds 

The following uncertainties and information gaps were identified as part of the problem 

formulation for propazine: 

$ Acute risks for freshwater fish were not characterized because the submitted study 

was determined to be invalid based on solubility issues. Uncertainty exists for the 

freshwater toxicity data for propazine until it can be shown that the tests were 

conducted up to the limit of solubility. 

b~reshwater fish may be surrogates for amphibians (aquatic phase). 

'Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of which one is soybeans. 

LDjo = Lethal dose to 50% of the test population; NOAEC = No observed adverse effect concentration; LOAEC = Lowest observed adverse 

effect concentration; LCjo = Lethal concentration to 50% of the test population; ECjolEC2, = Effect concentration to 50%125% of the test 

population. 

$ Chronic risk to avian species was not characterized because no studies with the 

TGAI were submitted. 

Taxonomic Group 

Terrestrial plants " 

Insects 

Aquatic plants and algae 

$ Current data were not available to determine the potential exposure to birds, 

mammals, and pollinators from residues on foliage, flowers, and seeds. 

represent surrogates for amphibians (terrestrial phase) and reptiles. 

Surrogate Species and 

Measures of Ecological Effect 

Monocot and dicot seedling 

emergence and vegetative 

vigor EC25, ECo5, and 

NOAEC values 

Honeybee acute contact LDSO (no 

study available) 

Algal and vascular plant (i.e., 

duckweed) ECSo and 

NOAEC values for growth 

rate and biomass 

measurements 

Assessment Endpoint 

(Abundance) 

Survival and growth 

Survival (not 

quantitatively assessed) 

Survival and growth 

$ No field toxicity studies are available. Spray drift presents a potential risk to nontarget plants inhabiting edge habitats adjacent to target fields and riparian 

vegetation along streams and/or ponds in close proximity to sprayed fields. 

Measures of Exposure 

Estimates of runoff and spray 

drifi to non-target areas 

Maximum application rate 

peak EEC 
$ Current data were not provided to determine the potential risks of propazine 

degradates to fish and aquatic invertebrate and terrestrial plant species. 

$ Dermal contact and soil ingestion pathways for terrestrial mammals and birds 

were not evaluated because these routes of exposure are not currently considered 

in deterministic risk assessments. Uncertainties associated with exposure 

pathways for terrestrial animals are discussed in greater detail in Section 1V.C. 

$ Risks to semiaquatic wildlife via consumption of pesticide-contaminated fish 

were not evaluated. However, given that bioaccumulation of propazine is 

expected to be low, ingestion of fish by piscivorus wildlife is not likely to be of 

concern. 

$ Risks to top-level carnivores were not evaluated due to a lack of data for these 

receptors. Ingestion of grass, plants, fruits, insects, and seeds by terrestrial 

wildlife was considered; however, consumption of small mammals and birds by 

carnivores was not evaluated. In addition, food chain exposures for aquatic 

receptors (i.e., fish consumption of aquatic invertebrates and/or aquatic plants) 

were also not considered. However, propazine's low &, suggests that it is not 

likely to bioaccumulate. 

$ Surrogates were used to predict potential risks for species with no data (i.e., 

reptiles and amphibians). It was assumed that use of surrogate effects data is 

sufficiently conservative to apply to the broad range of species within taxonomic 

groups. If other species are more or less sensitive to propazine and its degradates 

than the surrogates, risks may be under or overestimated, respectively. 

$ Fate studies indicate propazine is persistent and mobile raising concerns about the 

impact on groundwater and surface water. The field dissipation studies that have 

been submitted are considered unacceptable or supplemental resulting in a 

significant uncertainty for this transport pathway. Additional data is needed to 

comprehensively ascertain the mobility of propazine and its degradates under 

field conditions. 

111. ANALYSIS 

A. Use Characterization 

For this risk assessment, propazine comes in one formulation as an aqueous solution. 

Propazine is proposed for use as a selective herbicide in sorghum before planting or after 

planting but before sorghum or weeds emerge for control of annual broadleaf weeds. 

Application can be made via ground sprayer or aerial broadcast for sorghum. 

Formulations of propazine that are manufactured by Griffin L.L.C. include a 98% 

wettable powder technical product and a 43% flowable concentrate end use product 

(Propazine 4L). The proposed label for use of Propazine 4L o sorghum is provided in 

Appendix A. 
Figure 11-a 1. depicts areas in the US where sorghum was grown and harvested in 2003 

thus providing an indication of likely propazine use areas. Potential use areas are 

indicated in the Midwest states of Colorado, New Mexico, Kansas, Oklahoma, Texas and 

South Dakota, southern regions of Arizona and California, along the Mississippi river 

valley and along the eastern coastal regions of North Carolina and Maryland. 

In addition, the use of propazine on sorghum as specified on the proposed label prohibits 

use on sand, loamy sand, heavy clay, and high organic matter soils. As such, the risk 

conclusions contained in this assessment would not apply to these soil types. 

B. Exposure Characterization 

The propazine exposure characterization in this assessment combined the environmental 

fate data with Tier I1 exposure models to estimate environmental exposure concentrations 

(EECs). Exposure models estimate EECs following the conceptual diagram of propazine 

usage and potential exposure endpoints shown in Figure 11-b 2. EECs for aquatic 

endpoints are developed using the Tier I1 surface water models PRZMIEXAMS. These 

models determine EECs based on geographic areas nationwide and product use sites in 

close proximity to water bodies. The input parameters used in this assessment were 

selected from the environmental fate data submitted by the registrant and in accordance 

with US EPA-OPP EFED water model parameter selection guidelines, Guidance for 

Selecting Input Parameters in Modeling the Environmental Fate and Transport of 

Pesticides, Version 11, February 28,2002. A detailed aquatic resource exposure 

assessment is attached in Appendix C. The goal of Tier I1 aquatic modeling is to better 

define the range of EECs that can be reasonably expected under variable weather 

conditions. Likewise, EECs for birds and terrestrial mammals are estimated using the TREX 1.2.3 model and EECs for non-target plants are estimated by the TerrPlant 1.0 and 

AgDrifi 2.0.1 models. 

Griffin L.L.C. is seeking registration for propazine to be used as a selective herbicide in 

the control of annual grasses in sorghum (grain and sweet sorghum). 

1. Environmental Fate and Transport Characterization 

a. Summary of Empirical Data 

Environmental fate studies reviewed suggest that propazine is moderately persistent 

and mobile. If applied in an outdoor environment, propazine has a high potential to 

leach into ground water or reach surface waters by runoff. In areas where the soils 

are highly permeable, the water table is shallow, and sufficient precipitation andlor 

irrigation occur, the use of propazine may result in ground water contamination. A 

summary of some physical, chemical and fate properties of propazine is provided in 

Table 111-B 1. 
Adsorptiorddesorption 

Adsorptiorddesorption 

Adsorptiorddesorption 

Adsorption/desorption 

LC- ads (mLig) 

83 (loamy sand); 123 (sandy loam); 158 (loam); 

65(clay loam) 

Kd-a& 1 Kd-des (mLlg) 

0.67186.4 (sand,0.25 %OC, 7.6 pH); 1.2811 1.9 

(sandy loam; 1%OC, 6.8%pH); 1.30127.0 (silty 

clay; 1.36%OC, 5.9 pH); 1.3516.7 (loam; 

1.71%OC, 7.6 pH) 

KO,- ads (mL1g) 

268 (sand); 128 (sandy loam); 96 (silty clay); 79 

(loam) 

2-hydroxy-propazine 

&-ads Kd-des (mL1g) 

1.4516.61 (sandy loam); 0.2814.62 (sand); 

1.3313.12 (loam); 4.57112.36 (silty clay) 

436898-04 

442873-13 
b. Degradation and Metabolism 

Table 111-B 1. Physicochemical and Fate Properties of Propazine 

Existing laboratory studies indicate that propazine is stable to hydrolysis and 

photolysis (both aqueous and in soils). However, published literature on propazine 

and related chloro-s-triazines indicate that the chemical may be susceptible to 

hydrolysis afier adsorption onto the surface of soil colloids (a surface catalysis 

effect). Propazine is persistent under laboratory aerobic soil conditions with halflives ranging fi-om 15 weeks in loamy sand soil to 41 weeks in sandy loam soil. The 

major soil metabolite was 2-hydroxy propazine (2-hydroxy-4,6-bis(isopropy1amino)- 

s-triazine) and comprised a maximum of 3 1% of the total applied radioactivity (TAR) 

after one year. Minor degradates consist of desethylatrazine (2-amino-4-chloro-6- 

isopropylamino-s-triazine or DEA) (<2% of TAR) and 2-hydroxy desethylatrazine 

(<5% of TAR). No studies were submitted on the persistence of degradates (both 

major and minor) in the environment. Chemical structures of the propazine 

degradates are presented in Appendix B. 

Property 

Adsorption/desorption 

Terrestrial Field Dissipation 

Propazine is not likely to volatilize from near surface soils or surface waters under 

normal environmental conditions, due to its low vapor pressure (2.9 x ton. at 

20°C). If released to water, propazine is not expected to bioconcentrate in aquatic 

organisms, adsorb to sediment and/or suspended particulate matter, or to volatilize. 

This assessment assumes that propazine exhibits slow biodegradation in natural water 

based upon its biodegradation in soil, however, no data is available to confirm this 

assumption. 

c. Transport and Mobility 

Value 1 Reference (MRID) 

Propazine does not adsorb as strongly to soil particles as other triazine herbicides. In 

most soils used in batch equilibrium studies, especially sand and sandy loam soils, it 

binds weakly to soil particles (I(oc-ads = 268 and 128 mL/g, respectively). Literature 

&c- ads (mLig) 

145 (sandy loam); 329 (sand); 78 (loam); 

342 (silty clay) 

NC (Wilson Co) 1.2 lb aiIA - bare ground sandy 

loam (0-6") and sandy clay loam (6-12") 

t % = 7.2 days (1-21 days) 

t % = 58.2 days (28-184 days) 

TX (Armstrong Co) 1.2 lb ai1A - bare ground 

loamy sand (0-6" and 6- 12") 

T % = 52 days (186-day study) 

442873-14 

441848-09 
studies also showed that depending on soil temperature, moisture, and pH, it can 

become unbound (Worthing, 1983). The major degradate, 2-hydroxy propazine is 

slightly less mobile, with values ranging from 78 (loam) to 342 (silty clay) 

mL/g. In sand and sandy loam soils, the values are 329 and 145 mLIg, 

respectively. 

Based on the information summarized above, propazine is expected to be persistent 

and mobile in most soils, and it is resistant to breakdown by hydrolysis, photolysis, or 

biodegradation. The mobility of propazine is also noted in the fields, where 

supplemental terrestrial field dissipation studies suggest that propazine dissipates 

slowly from the upper 6 inches (half-lives of 5 1 days in TX, and 7 to 58 days in NC, 

<30 to 149 days in NY, <3 1 days in CA, and 60 to >357 days in NE) and may leach 

to ground water. It has also been reported in the literature that if released to soil, 

propazine will persist longer in dry or cold conditions or other conditions which 

inhibit biological and chemical activity (Worthing, 1983). It is therefore very likely 

that in areas where soils are highly permeable, the water table is shallow, or where 

there is irrigation and/or high rainfall, the use of propazine may result in ground water 

contamination. 

d. Field Studies 

The four submitted field studies were either unacceptable or considered supplemental 

because of inadequate sampling depths (only the upper 12 inches were sampled), lack 

of freezer stability data (some samples were frozen for up to 3 years), andlor the 

presence of propazine in the control and treated plots prior to the start of the study. 

Supplemental data suggest that propazine, applied as a wettable powder at 2.4 to 4.8 

lb a.i./A/yr, dissipated from the upper 6 inches with a half-life of <30 to 149 days in 

NY, <3 1 days in CA, and 60 to >357 days in NE. The degradates hydroxy-propazine, 

G-2873 [2-chloro-4,6-diamino-s-triazine], and G-30033 [2-chloro-4-amino-6- 

isopropylamino-s-triazine] were detected in one or more of the field studies (NY, CA, 

NE). 

The major laboratory soil degradate, 2-hydroxy propazine was seen in the 0-3" and 3- 

6" soil layers of the terrestrial field studies at approximately 15% of parent at day 1, 

and decreased to less than 5% of parent by day 93. The other two minor degradates 

desethylatrazine (DEA) and 2,4-diamino-6 chloro-s-triazine (DACT), which are 

common to atrazine and simazine, were detected only in the 0-3" soil layer, each at 

less than 5% of parent at day 1, however decreasing to less than 1% by day 28. 

e. Review of Published Literature on the Environmental Fate of Propazine 

The environmental fate of propazine in published scientific literature is limited and 

published studies vary in quality and usually contain insufficient information on 

procedures or raw data to adequately assess the results. However, these research 

findings can provide supplemental information on the environmental fate of 

propazine. The following discussion comes primarily fiom three published reviews - 
Khan (1980), Montgomery (l993), and Wolfe et a1 (1990) - which summarize several 

published studies. 

Propazine, like the other triazine chemicals, is weakly basic (pKa .1.85 at 22OC; 

Montgomery, 1993), can be easily protonated at low soil pH values, and is likely to 

exist as a neutral species at soil pH values more than two pH units above the pKa 

(Koshinen and Harper, 1990). Adsorption of protonated propazine is pH-dependent, 

with a maximum adsorption at or near the pKa (Khan, 1980). Soil organic matter 

plays an important role in the adsorption of propazine and other s-triazines, affecting 

their movement in soil (Hayes, 1970). 

The chemical hydrolysis of s-triazines, including propazine, is catalyzed by surface 

adsorption on soil colloids (Khan, 1980; Wolfe et al, 1991). Studies by Russell et a1 

(1 968), Brown and White (1 969), and Nearpass (1 972) found evidence that the 

chemical hydrolysis of propazine was catalyzed by adsorption onto organic matter 

and clay. 

Montgomery (1 993) summarized soil adsorption data fkom four studies (Burkhard 

and Guth, 198 1 ; Harris, 1966; Talbert and Fletchall, 1965; Walker and Crawford, 

1970) involving 3 8 soils. The reported adsorption Kd values averaged 3.4 mL/g, with 

a range of 0.1 to 20.5. In 35 of the 38 soils, the Kd values were less than 4.7. The Kc 

values averaged 155 mL/g (ranging from 29 to 363), which are within the range of the 

K,, values reported in the above mentioned environmental fate studies submitted by 

the registrant. 

Measures of Aquatic Exposure 

a. Aquatic Exposure Modeling 

Tier I1 Estimated Environmental Concentrations (EEC) for propazine were estimated 

using EFED's aquatic models PRZM and EXAMS. PRZM is used to simulate 

pesticide transport as a result of runoff and erosion from an 10-ha agricultural field 

and EXAMS considers environmental fate and transport of pesticides in surface water 

and predicts EECs in a standard pond (1 0,000-m2 pond, 2-m deep) with the 

assumption that the small field is cropped at 100%. Calculations are carried out with 

the linkage program shell - PE4VOl .pl - which incorporates the standard scenarios 

developed by EFED. Additional information on these models and crop scenarios can 

be found at: http::i\vu \v.epa.~c~r~/op13efcct 1 /models 'waterhndexhtm. 

The proposed agricultural use of propazine for broadleaf weed control in sorghum 

was simulated with the sorghum crop scenarios for Texas and Kansas. The Texas and 

Kansas crop scenarios were chosen as they are the two states with the most harvested 

acreage of sorghum. Kansas ranks first in the nation for sorghum production with 

220 million bushels harvested in 2004 while Texas ranks second (1 14 million bushels 

in 2002). 
The maximum application rate (1.2 lb a.i./A from the proposed propazine 4L label) 

was modeled for the Kansas and Texas sorghum scenarios. Application dates were 

based on the propazine label information as well as on reported planting dates stated 

in the USDA crop profiles for sorghum grown in Texas and Kansas. Based on the 

environmental fate data described above (Section II1.B. I .) and sorghum crop 

scenarios, EECs for aquatic exposure were estimated. Table 111-B2. contains the 

propazine input parameters for the PRZMIEXAMS models. Note that the Texas 

sorghum scenario was developed for the cumulative assessment for the 

organophosphate insecticides it was used in this assessment to provide spatial context 

to the EEC generated using the Kansas sorghum scenario. 

EEC's were developed for the parent propazine only (Table 111-B3.); as insufficient 

data exist to fully assess the persistence and mobility of propazine's major degradate, 

hydroxy-propazine [2-hydroxy-4,6,bis(isopropylamino)-s-triazine] in the 

environment. Furthermore, based on the risk assessment of the atrazine and simazine, 

hydroxy-propazine was not considered to be of toxicological concern to human 

health. The minor degradates DEA and DACT, although of equal potency 

toxicologically compared to parent propazine, were also not included in this 

assessment mostly due to their low detection in the laboratory soil metabolism studies 

and in the terrestrial field studies (less than 5% of Total Applied Radioactivity 

(TAR)). For atrazine and simazine, these chlorinated degradates were formed at 

much higher percentage, and ample monitoring data were available to adequately 

estimate their concentrations versus those of the parents. However, for propazine, 

minimal monitoring data exist for an adequate quantitative assessment of the 

chlorinated degradates. Additionally, as mentioned above, laboratory and field 

studies indicate that DEA and DACT, if formed in the environment, would not be 

present nor would persist at any significant concentration compared to parent 

propazine to adversely impact the results of the ecological risk assessment, as 

presented in this document. 

The proposed propazine label for sorghum stipulates buffer, or setback, distances for 

surface water bodies adjacent to treated fields. The label specify setback distances of 

66 feet and 200 feet for propazine applications surrounding intermittent/perennial 

streams and lakes/reservoirs, respectively. These distances were incorporated into 

this assessment using AgDrifi to estimate the impact of a setback distance of 66 feet 

on the fraction of drift reaching a surface water body. The revised spray drift 

percentages, which are incorporated into the PRZMIEXAMS modeling, are 0.6% for 

ground applications and 6.5% for aerial applications. 

Models to estimate the effect of setbacks on load reduction for runoff are not 

currently available. It is well documented that vegetated setbacks can result in a 

substantial reduction in pesticide load to surface water (USDA, NRCS, 2000). It is 

expected that the presence of a well vegetated setback between the site of propazine 

application and receiving water bodies could result in reduction in loading. 

Therefore, the aquatic EECs presented in this assessment are likely to over-estimate 

exposure in areas with well-vegetated setbacks. While the extent of load reduction 
can not be accurately predicted through each relevant stream reach in the action area, 

data from USDA (USDA, 2000) suggest reductions could range from 1 1 to 100%. 

b. Aquatic Exposure Monitoring and Field Data 

Several sources of surface water monitoring data were reviewed, including data from 

USGS reconnaissance studies, USGS National Water Quality Assessment Program 

(NAWQA) and the US EPA's Office of Water STORET Database (1 997). The USGS 

reconnaissance post application monitoring data were performed on numerous 

streams within the 10 states comprising the Midwestern corn belt in 1989, 1990, 

1994, and 1995. The maximum propazine contamination was detected in Ohio at 3.8 

ppb. The reason for this high detection is uncertain given that Ohio is not a sorghum 

growing area (Figure 11-a 1) but it could possibly be associated with the only other 

registered use on nurseries. Although these data provide useful information, Kansas 

and Southern Nebraska were the only areas in the primary propazine market area 

covered by this USGS study. Furthermore, multiple pesticide residue studies not 

designed specifically for propazine may include many sampling stations outside of 

propazine use areas even within Kansas and Southern Nebraska. 

A review of the STORET Database (1 997) reports concentrations of propazine 

residues ranging from 9.1 to 105 ppb for Kansas (detection limits of 0.5 to 1.2 ppb), 

and from 0.4 to 2.1 ppb for Texas (detection limit of 0.1 ppb) and 0.1 to 0.3 ppb 

(detection limits of 0.1 ppb) in Oklahoma. There was no detection in surface water 

for Colorado and New Mexico. Overall, propazine was found in 33 out of 1,097 (3% 

frequency of detection) surface water samples reported in these references for states 

located in the Midwest. 

A review of surface water and groundwater monitoring data collected as part of the 

USGS NAWQA program reports detects of propazine in water samples from several 

areas in the US (http://water.usgs.gov/nawqa~). NAWQA monitoring data from 1991 

to 2005 indicate propazine groundwater concentrations of 0.25 - 1.7 ppb (5 detects 

out of 61 samples, or 8.2% frequency of detection) in Nebraska and surface water 

concentrations of 0.06 - 1.08 ppb (79 detects out of 136 samples, or 58.1% frequency 

of detection). Monitoring data from Iowa indicates no detects in groundwater (145 

samples) and surface water concentrations of 0.06 - 0.36 ppb (25 detects out of 63 

samples, or 39.7% frequency of detection). Texas surface water monitoring data 

shows two detects (0.06 and 0.3 1 ppb) out of 25 samples (8% frequency of detection) 

while surface water data for the Mississippi River Embayrnent (MO, AR, MS, LA) 

indicates propazine concentrations of 0.06 - 0.85 ppb (22 detects in 67 samples, or 

32.8% frequency of detection). Another 65 samples from the upper Mississippi River 

valley and the northeast US (NY, CT, DE) showed no detection of propazine 

(detection limit of 0.05 ppb). 

Nationally, a total of 140 out of 562 surface water samples (24.9% frequency of 

detection) contained concentrations of propazine above the limit of quantitation. The 

maximum concentration detected was 1.69 ppb in Nebraska, while the average 
concentration from all detections was 0.21 ppb. The bulk of the detections from this 

analysis were in Nebraska with fewer detections in Iowa, Missouri, and Louisiana. 

Although limited monitoring data were available, data were not abundant in the areas 

of high propazine use and high run off potential, such as the coastal areas of Texas. 

Furthermore, for some of the data the quality of the available monitoring data is not 

sufficiently reliable and at times could not be adequately or reasonably assessed due 

to the following problems: 

information about the application dose or rate, areas of pesticide use, and farming 

practices involving application frequency and irrigation are insufficient or not 

available; 

the STORET monitoring database is a collection of isolated studies because the 

monitoring activities were not performed in a consistently uniform manner due to 

differences in study designs that radically affected the results; 

characterization of the sampling sites such as susceptibility of the watershed soils 

to runoff, soil index, monthly precipitation, and residence times of surface water 

bodies is inadequate; 

for the STORET data the integrity of the sampling techniques, preservation 

procedures, and storage methods are questionable or sometimes not documented; 

and, analytical methods and limits of detections are different in several 

monitoring studies, thus contributing to difficulty in data interpretation. Surface 

water monitoring results are presented here to corroborate the ability of propazine 

to contaminate surface waters and should be used qualitatively only. 

Table 111-B 2. PRZMIEXAMS Input Parameters for Propazine 

Parameter 

Application Rate per Event 

Number of Applications per 

Crop Season 

Aerobic Soil Metabolism 

t% 

Anaerobic Soil Metabolism 

t% 

Spray Drift Fraction 

Application Efficiency 

Value 

1.2 lb a.i./A 

1 application per year 

480 days ' 

56 days 

0.006 / 0.065 

0.99 10.95 

Comment 

aerial and ground spray 

application to sorghum 

estimated upper 9oth 

percentile 

ground / aerial 

ground I aerial 

Source 

Propazine 4L label 

Propazine 4L label 

MRID 44 1848-07 

MRID 001 537-13 

AgDrift Modeling for 

label specified buffers 

EFED Guidance, 2002 
I Table 111-B 2. PRZMJEXAMS Input Parameters for Propazine I 

Parameter 

Degradation t % 

Anaerobic Aquatic 

Degradation t % 

Aqueous Photolysis t 95 

Hydrolysis t % 

Value 

Soil Partition Coefficient 

(Koc) 

Molecular Weight 

Source 

EFED Guidance. 2002 

Comment 

Aerobic Aquatic 

112 days " 

Stable 

Stable 

I I 

EFED Guidance, 2002 

960 days ' ) No data; estimated 

(2x aerobic soil 

metabolism half-life) 

No data; estimated 

(2x anaerobic soil 

metabolism half-life) 

PH 7 

125 mL/g4 

230 glmole 

Water Solubility @ 20°C 

MRID 441 848-05 

Average KO, 

2.9 mg/L 

MRID 436898-02 

MRIDs 001 529-97, 

436898-04 

Product Chemistry 

Product Chemistry 

I Table 111-B 3. Estimated Environmental Concentrations (pglL) of Propazine in Surface Water I 

I I I 

Vapor Pressure 

Sorghum (TX) 

Aerial spray 

89.8 89.8 88.1 85.1 83.0 67.0 45.6 

Ground spray 

82.0 81.7 80.4 77.6 75.7 60.8 39.0 

Simulation Scenario 

Sorghum 

(1.2 lb a.i./A) 

* One in ten year value 

Input and output for PRZM3.12IEXAMS2.98 modeling is presented in Appendix C. 

I 

Upper 90Ih Percentile based on mean half-lives of 289 and 105 days. ' 2x aerobic soil ~netabolism half-life (EFED Modeling Input Parameter Guidance, 2002). 

2x anaerobic soil metabolism half-life (EFED Modeling Input Parameter Guidance, 2002). ' Average ti-om all acceptable adsorptionldesorption data including KO, values of 65, 83, 123, 158, 79, 96, 128, and 268 

(MRIDs 001 529-97 and 436898-04 ). 

2.9E-8 tom 

3. Measures of Terrestrial Exposure 

I Product Chemistry 

Sorghum (KS) 

Aerial spray 

53.9 53.8 53.2 52.0 51.0 44.9 35.7 

Ground spray 

40.8 40.7 40.2 39.5 38.8 33.9 25.8 

Concentration (pg!~)* 

a. Terrestrial Exposure Modeling 

--...---.. .~~~.--~------~-----~~--- 

Peak 96 hour 21-day 

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

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

exposures are considered as surrogates for terrestrial-phase amphibians as well as 

reptiles. For exposure to terrestrial wildlife, such as birds and small mammals, pesticide 

residues on food items are estimated, based on the assumption that organisms are exposed 

to a single pesticide residue in a given exposure scenario. For this terrestrial exposure 

assessment, aerial and ground spray application methods for propazine are considered. 

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

60-day 90-day Annual Yearly 

Mean Average 
For propazine spray applications, estimation of pesticide concentrations in wildlife food 

items focuses on quantifying possible dietary ingestion of residues on vegetative matter 

and insects. No field residue data or field study information is available; therefore, the 

residue estimates are based on a nomogram that relates food item residues to pesticide 

application rate. The EECs are generated from a spreadsheet-based model (T-REX 

Version 1.2.3) that calculates the decay of a chemical applied to foliar surfaces for single 

or multiple applications. Terrestrial EECs estimated using the T-REX model are 

presented in Table 111-B4. 

The terrestrial exposure assessment is based on the methods of Hoerger and Kenaga 

(1972) as modified by Fletcher et al. (1994). Terrestrial EECs for aerial and ground 

spray applications were derived for sorghum. Uncertainties in the terrestrial EECs are 

primarily associated with a lack of data on interception and subsequent dissipation fi-om 

foliar surfaces. When data are absent, as in this case, EFED assumes a 35-day foliar 

dissipation half life, based on the work of Willis and McDowell(1987). For propazine, 

EFED assumed a default half life of 35 days. 

The EECs on food items may be compared directly with dietary toxicity data or 

converted to an oral dose, as is the case for small mammals. The risk assessment for 

propazine uses upper bound (i.e., 9oth percentile) and mean predicted residues as the 

measure of exposure on selected avian or mammalian food items immediately following 

propazine application (at the maximum label rate) for sorghum. For mammals, the 

residue concentration is converted to daily oral dose based on the fraction of body weight 

consumed daily as estimated through mammalian allometric relationships. 

Effects on non-target terrestrial plants are most likely to occur as a result of spray drift 

andlor runoff fi-om aerial and ground applications of the liquid formulation. Spray drift 

and runoff is an important factor in characterizing the risk of propazine to non-target 

plants, which is assumed to reach off-site areas. The TerrPlant model (Ver. 1 .O) predicts 

EECs for terrestrial plants located in dry and semi-aquatic areas adjacent to the treated 

field. The EECs are based on the application rate and solubility of the pesticide in water 

and drift characteristics, which depend on ground or aerial applications. The amount of 

propazine that runs off is a proportion of the application rate and is assumed to be 1% 

based on propazine's solubility of <10 ppm in water. Drift from ground and aerial 

applications are assumed to be 1 % and 5%, respectively, of the application rate. For dry 

areas, the loading of pesticide active ingredient from runoff to an adjacent non-target area 

is assumed to occur from one acre of treatment to one acre of non-target area and is 

characterized as "sheet runoff '. For terrestrial plants inhabiting semi-aquatic (wetland) 

Table 111-B 4. Terrestrial Bird and Mammal EEC's (Residues) Following Application of 

Propazine to Sorghum 

Terrestrial 

Use 

Sorghum 

Application. Rate 

(Ibs a.i./A) 

1.2 

Food Items 

Short Grass 

Tall Grass 

Sm. Insects, Broadleaf Plants 

Lg. Insects, Fruits, Pods 

Maximum EEC 

(mg/L) 

288 

132 

162 

18 

Mean EEC 

(mg/L) 

102 

43 

54 

8 - 
areas, runoff is considered to occur from a larger source area with active ingredient 

loading originating from 10 acres of treated area to a single acre of non-target wetland 

and is characterized as "channelized runoff". Predicted terrestrial plant EECs following 

ground and aerial spray applications of propazine to sorghum are summarized in 

Table 111-B5. 

I I I I I ' EEC = Sheet Runoff + Drift (I % for ground; 5% for aerial) ' EEC = Channelized Runof+ Drift (1 % for ground; 5% for aerial) 

' EEC for ground (appl. rate x 1 % drift); for aerial (appl. rate x 5% drift) 

Table 111-B 5. EECs for Terrestrial Plants Located Adjacent to Propazine Treated Sorghum Fields 

C. Ecological Effects Characterization 

Terrestrial Use 

Sorghum 

(1.2 lbs a.i.1A) 

1. Aquatic Effects Characterization 

Table 111-C 1 presents the toxicity endpoint values from the studies used to calculate RQs 

and estimate risk to aquatic receptors from exposure to propazine through surface 

runofflleaching. Details of the registrant-submitted studies for aquatic animals and plants 

are provided below and in Appendix F. 

Application 

Method 

Aerial 

Ground 

Concentration (lbs a.i./A) 

Table 111-C 1. Propazine Toxicity Endpoint Values for Assessing Risk to Aquatic Organisms 

Total Loading to Areas 

Adjacent to Treated 

 rea as' 

0.067 

0.024 

Exposure 

Scenario 

Total Loading to SemiAquatic Areas Adjacent 

to Treated re as' 

0.132 

0.132 

Species 

Drift to 

Adjacent ~reasj 

0.06 

0.012 

Freshwater Fish 

Exposure 

Duration 

Acute 

Chronic 

Toxicity Endpoint Value 

No valid studies available 

Fathead minnow 

Pirnephales promelas 

Freshwater Invertebrates 

Endpoint 

Acute 

Chronic 

Reference 

(Classification) 

Early life 

stage 

Water flea 

Daphnia magnn 

Water flea 

Daplznia magnu 

NOAEL = 0.72 mg ai/L 

EstuarineIMarine Fish 

48 hours 

2 1 days 

Acute 

Chronic 

Reduction in 

length 

MRID 442873-07 

(Supplemental) 

ECso = >5.32 ppm ai 

NOAEC = 5.32 ppm ai 

NOAEC = 0.047 ppm ai 

LOAEC = 0.09 1 ppm ai 

EstuarineIMarine Invertebrates 

No data submitted 

Sheepshead minnow 

Cyprinodon variegatus 

Lethality 

Growth 

MRID 442873-05 

(Awaiting final 

EFED review) 

MRID 443276-02 

(Core) 

36-day NOAEC = 1.34 mg ai/L 

LOAEC = 2.59 mg ailL 

Embryo 

survival; 

hatching 

success 

MRID 44 1848-02 

(Awaiting final 

EFED) 
a. Aquatic Animals 

Table 111-C 1. Propazine Toxicity Endpoint Values for Assessing Risk to Aquatic Organisms 

(I) Freshwater Fish and Invertebrates, Acute 

Exposure 

Scenario 

Acute 

Chronic 

Fish toxicity studies for two freshwater species using the TGAI are required to 

establish the acute toxicity of propazine to fish. The preferred test species are 

rainbow trout (a coldwater fish) and bluegill sunfish (a warmwater fish). No valid 

acute freshwater fish studies are available for either the parent propazine or the 

degradates. 

A freshwater aquatic invertebrate toxicity test using the TGAI is required to establish 

the toxicity of propazine to aquatic invertebrates (Table 111-C2). The preferred test 

species is Daphnia magna. A submitted acute study for daphnids provided a 48-hr 

ECSo value of >5.32 pprn ai (NOAEC 5.32 pprn ai) for the TGAI. This value will be 

used to assess acute risk of propazine to freshwater invertebrates (MRID 442873-05). 

The classification of this study is currently being reevaluated in order to determine if 

daphnids were exposed to propazine at the limit of solubility. In addition, no toxicity 

data are available to assess the acute risk of the degradates to freshwater invertebrate 

species. 

Species 

Saltwater mysid 

Mysidiopsis bahia 

Saltwater mysid 

Mysidiopsis bahia 

Aquatic Plants 

(2) Freshwater Fish and Invertebrates, Chronic 

Exposure 

Duration 

96 hours 

28-day 

Nonvascular 

Macrophytes 

Table 111-C 2. Freshwater Invertebrate Acute Toxicity for Propazine 

For freshwater fish chronic studies (early life-stage or a full life-cycle test) the 

preferred species is the fathead minnow. In an early life-stage study, propazine 

induced a significant reduction in length with a NOAEL of 0.72 mg ai/L (Table IIIC3.). This value will be used to assess the chronic risk of propazine to freshwater fish 

(MRID 442873-07). The study was classified as supplemental because pH and 

Species 

Waterflea 

(Daphnia magna) 

Toxicity Endpoint Value 

= 4.20 ppm ai 

NOAEC = 0.586 ppm ai 

NOAEC = 0.269 ppm ai 

LOAEC = 0.706 ppm ai 

Diatom 

Navicula pelliculosa 

Duckweed 

Lemna gibba 

% ai 

98.0 

Endpoint 

Lethality 

Growth; 

Reproduction 

120 days 

120 days 

Reference 

(Classification) 

MRID 44 1848-0 1 

(Acceptable) 

MRID 44 1848-03 

(Supplemental) 

48-hour EC50 

(PP~ ai) 

>5.32 

ECso = 0.0248 ppm ai 

NOAEC = 0.0065 ppm ai 

EC50 = 0.10 ppm ai 

NOAEC = 0.022 ppm ai 

Cell density 

Frond density 

Study 

Classification 

Awaiting final 

EFED review 

Toxicity Category 

moderately toxic 

MRID 442873- 10 

(Core) 

MRID 442873-09 

(Core) 

MRID No. 

Author, Year 

442873-05 

Murrell, 1994 
hardness exceeded recommended levels, potentially affecting solubility. No toxicity 

data are available to assess the chronic risk of the degradates to freshwater fish 

species. 

For life-cycle studies on freshwater invertebrates, the preferred test species is 

Daphnia magna. Submitted data show reductions in growth (length and weight) in 

daphnids following exposure to propazine. The NOAEC of 0.047 ppm ai will be used 

to assess chronic risk of propazine to freshwater invertebrates (MRID 443276-02). 

No toxicity data are available to assess the chronic risk of the degradates to 

freshwater invertebrate species. 

Table 111-C 3. Freshwater Fish Chronic Toxicity for Propazine 

Acute and chronic toxicity testing with estuarinelmarine fish and invertebrates using 

the TGAI is required for propazine because the end-use product is expected to reach 

the marinelestuarine environment. Propazine is expected to be used in coastal county 

locations where sorghum may be grown (i.e. Texas, North Carolina, Maryland and 

Louisiana (Figure 11-a 1)). 

Species 

Table 111-C 4. Freshwater Invertebrate Chronic Toxicity for Propazine 

(3) Estuarine/Marine Fish and Invertebrates, Acute 

Early Life Stage Study under Flow-through Conditions 

Fathead minnow 98.0 0.7211.14 Growth 442873-07 Supplemental 

(Pimephales promelas) Rhodes, 1995 

MRID No. 

Author, Year 

For acute toxicity testing with estuarinelrnarine fish, the preferred test species is 

sheepshead minnow. No toxicity studies were submitted by the registrant to assess 

the acute risk of propazine or its degradates to estuarinelmarine fish species. 

Study 

Classification 

Study 

Classification 

Core 

Species 

Waterflea 

(Daphnia magna) 

For acute toxicity testing with estuarinelmarine invertebrates, the preferred species 

are the mysid shrimp and eastern oyster. Propazine is categorized as moderately toxic 

to the mysid shrimp, based on mortality and sublethal effects (LCso = 4.20 ppm ai). 

Propazine is categorized as practically non-toxic to the eastern oyster at the limit of 

solubility with an ECS0 >3.72 mg ai1L (MRIDs 441848-01 and 442873-06). The 

oyster study was originally classified as supplemental; however, EFED reevaluated 

Endpoints 

% ai Affected 

NOAELLOAEL 

(mg ailL) 

% a.i. 

98.0 

21-day 

NOAECILOAE 

C (ppm ai) 

0.04710.091 

Endpoints 

Affected 

Growth 

MRID 

Author, Year 

443276-02 

Murrell & 

Veltri, 1997 
the data and established these effect levels (Table 111-C5). No toxicity data are 

available to assess the acute risk of the degradates to estuarinelmarine invertebrate 

species. The LC5() = 4.20 ppm in the mysid study will be used to assess acute risk to 

marinelestuarine invertebrates. 

(4) Estuarine/Marine Fish and Invertebrates, Chronic 

Table 111-C 5. EstuarineIMarine Invertebrate Acute Toxicity for Propazine 

For the chronic toxicity testing with estuarinelmarine fish the preferred test species is 

sheepshead minnow. In an early life-stage study, propazine affected embryo survival 

and hatching success at 2.59 mg ai1L (Table 111-C6). The NOAEC of 1.34 mg ai/L 

will be used to assess the chronic risk of propazine to estuarinelrnarine fish (MRID 

441 848-02). This study was originally classified as supplemental; however, EFED 

reevaluated the data and established these effect levels. No toxicity data are available 

to assess the chronic risk from the degradates to estuarinelmarine fish species. 

Species 

Eastern oyster 

(Cmssostrecr virginica) 

Mysid 

(Mysidopsis bnhin) 

For the life-cycle toxicity study with estuarine/marine invertebrates, the preferred test 

species is mysid shrimp. The data submitted indicate that propazine produced 

significant effects to growth and reproduction at 0.706 ppm ai. The NOAEC of 

0.269 ppm ai will be used to assess the chronic risk of propazine to estuarine/marine 

invertebrates (MRID 441 848-03); the study was classified as supplemental due to 

deviations in study design. No toxicity data are available to assess the chronic risk of 

the degradates to estuarine/marine invertebrate species. 

% a.i. 

98.0 

98.0 

Table 111-C 6. EstuarineIMarine Fish Chronic Toxicity for Propazine 

Species 

96-hour 

EC5dLCso 

13.72 mg ai/L 

4.20 ppm ai 

% ai 

Toxicity Category 

practically nontoxic 

moderately toxic 

Early Life Stage Study under Flow-through Conditions 

NOAECILOAEC 

(mg ailL) 

Sheepshead minnow 

(Cyprinodon 

vnriegatus) 

MRID 

Author, Year 

442873-06 

Boeri et al., 1995 

44 1848-0 1 

Boeri et al., 1995 

Study 

Classification 

Awaiting final 

EFED review 

Acceptable 

Endpoints 

Affected 

98.0 

MRID No. 

Author, Year 

1.3412.59 

Study Classification 

Growth 44 1848-02 

Boeri et al., 1995 

Awaiting EFED 

validation 
b. Aquatic Plants 

Several aquatic plant toxicity studies using the TGAI are required to establish the 

toxicity of propazine to non-target aquatic plants. The recommendation is for testing 

of five species: freshwater green alga (Selenastrum capricornutum), duckweed 

(Lemna gibba), marine diatom (Skeletonema costaturn), blue-green algae (Anabaena 

flos-aquae), and a freshwater diatom (Navicula pelliculosa). In a Tier I1 toxicity test, 

the 14-day EC50 for the freshwater vascular plant (duckweed) is 0.10 ppm ai 

(NOAEC = 0.022 ppm ai), based on frond density; and the lowest 7-day ECS0 for the 

freshwater non-vascular plant (diatom) is 0.0248 ppm ai (NOAEC = 0.0065 ppm ai), 

based on cell density. These values will be used to assess the risk of propazine to 

aquatic vascular and nonvascular plants (Table 111-C8). 

The Tier I1 results for propazine degradates indicate that the most sensitive algae of 

the five species is generally the blue-green alga Anabaena inaequalis with ECso 

values ranging from 100 to > 100,000 ppb. All studies were classified as 

supplemental because NOAEC and raw data were unavailable. 

a. Terrestrial Animals 

(I) Birds, Acute and Subacute 

An oral toxicity study using the technical grade of the active ingredient (TGAI) is 

required to establish the acute toxicity of propazine to birds. The preferred guideline 

test species is either mallard duck (a waterfowl) or bobwhite quail (an upland 

gamebird). The submitted acute data indicate that propazine is at most slightly toxic 

to upland gamebirds with an acute oral LDso value of >1,640 mg aikg (Table IIIC 1 1). The NOAEL was determined to be 244 mg ailkg, based on weight loss (MRID 

442873-01). 
The results of the acute avian oral LDS0 study with DEA show that it is slightly toxic. 

Ten, forty, ninety, and one-hundred percent mortality was observed in quail exposed 

to DEA at 445,735, 1212, and 2000 mag-bw by 14 days (MRID # 465000-09). In 

addition, sublethal treatment-related effects, including reductions in body weight gain 

and food consumption, were observed at 270 mag-bw (lowest dose tested) and 

above. 

Two dietary studies using the TGAI are required to establish the subacute toxicity of 

propazine to birds. The preferred test species are mallard duck and bobwhite quail 

(Table 111-C 13 .). The data that were submitted show that the 8-day acute dietary 

LCSO's were >4,930 ppm and >5,140 for bobwhite quail and mallard, respectively; 

therefore, propazine is at most, categorized as slightly toxic to upland game birds on a 

subacute dietary basis (MRIDs 442873-02 and MRID 442873-03). 

(2) Birds, Clzronic 

Avian reproduction studies using the TGAI are usually required for pesticide 

registration because birds may be subject to repeated or continuous exposure to the 

pesticide, especially preceding or during the breeding season. The preferred test 
species are mallard duck and bobwhite quail. No avian reproduction studies were 

submitted by the registrant. 

(3) Mammals, Acute 

Wild mammal testing is required on a case-by-case basis, depending on the results of 

lower tier laboratory mammalian studies, intended use pattern and pertinent 

environmental fate characteristics. In most cases, rat or mouse toxicity values 

obtained from the Agency's Health Effects Division (HED) substitute for wild 

mammal testing. These toxicity values are reported below (Tables 111-C14 and 111- 

C15). The results indicate that propazine is categorized as practically non-toxic 

(Toxicity Category IV) to small mammals on an acute oral basis (LD50 value >5,050 

mg/kg; MRID 43474 1-0 1). 

The acute mammalian oral toxicity study with the degradate deethylatrazine (DEA) 

provides LDS0 values between 668 and 188 1 mag, indicating that it is slightly toxic 

when administered via the oral route (Table 111-C1 5). 

(4) Mammals, Developmental/Reproductive 

Table 111-C 15. Mammalian Acute Toxicity for the Degradate Deethylatrazine 

In developmental toxicity studies, administration of propazine by gavage produced 

maternal toxicity in both Sprague-Dawley rats and New Zealand rabbits with a 

NOAEL of 10 mg/kg bwlday (Table 111-Cl6). Decreased ossification was also 

observed in offspring of rats, resulting in a developmental NOAEL of 10 mg/kg/day. 

No treatment-related effects in developmental parameters were observed in rabbits. 

Salivation was also observed in rats at doses 2500 mg/kg/day (MRIDs 001502-42 and 

441 534-01). 

Species 

In a 3-generation reproduction study with rats exposed to propazine, no treatmentrelated effects on reproduction were observed; consequently, the NOAEL for 

reproductive toxicity was 250 mg/kg bwlday. Based on decreased body weights in 

males and females, the parentalloffspring NOAEL was 5 mg/kg/day. This value will 

be used to assess the chronic risk of propazine to mammals (MRID 000414-09). 

Laboratory rat 98.0 668 mglkg LD5o 430132-02 Core 

(Rattus nonlegicus) 1,88 1 mglkg (mortality) Kuhn, 199 1 

% ai 

Toxicity 

Value 

Affected 

Endpoints 

MRID No. 

Author, Year 

Study 

Classification 
I Maternal toxicity - Decreased body weight and food consumption; salivation was also observed. 

Developlnental toxicity - Decreased ossification. ' Maternal toxicity - Decreased body weight gain and food consu~nption 

Developlnental toxicity - No treatment-related effects were observed. 

%arental/offspring toxicity - Decreased body weights in males and females 

Reproductive toxicity - No treatment-related effects were observed. 

In subchronic studies with the degradates, it appears that deethylatrazine (DEA) and 

diaminochlorotriazine (DACT) also produced decreased body weights in rats at doses 

as low as 25 ppm ai and 250 ppm ai, respectively (Table 111-C17). DEA and DACT 

also resulted in developmental effects in rats at 100 ppm ai (fused sternebrae and poor 

ossification) and 500 ppm ai (embryo resorption and poor ossification), respectively. 

Table 111-C 17. Mammalian Subchronic and Reproduction Toxicity for the Propazine Degradates 

Species 

Laboratory rat 98.2 NOAEL < 100 red. LH and prolactin 4 15 109-0 1 Supplemental 

(Rattus DACT LOAEL 100 levels Hazleton 

nowegicus) (G-28273) Lab., 1990 

Fed for 14 200 red. estrogen, LH, 

days prolactin and progesterone 

Laboratory rat 95.7 NOAEL 50 red. in female body weight 430132-06 Acceptable- 

(Rattus DEA LOAEL 500 red. in food efficiency for Ciba- Guideline 

nowegicus) (G-30033) male and female rats Geig~, 

13-week diet 1991 

Laboratory rat 98.2 NOAEL 10 Estrous cycle effects in 430132-07 Core-Guideline 

(Rattus DACT LOAEL 100 female rats Cibanor-vegicus) (G-28273) Geig~, 

13-week diet NOAEL 100 red. body weight gain in 1991 

LOAEL 250 males and female Week 12 

Dog - 95.7 NOAEL 100 red. body weight & weight 430132-04 CoreBeagle DEA LOAEL 1,000 gain in males and females; Ciba- Minimum 

LOAEL Endpoints % ai 

MRID No. 

Year (PP~ ai) 

Study 

~lassification 
(5) Insects, Acute Contact 

Table 111-C 17. Mammalian Subchronic and Reproduction Toxicity for the Propazine Degradates - 

In an acute contact study with the honey bee, propazine was determined to be 

relatively non-toxic. At 96 hours, mortality was 2.47% at a dose of 96.69 pglbee 

(Atkins et al. 1975). The study was scientifically sound and showed that propazine is 

relatively non-toxic to honey bees. 

Species 

(6) Insects, Residual Contact 

No residual contact toxicity study was submitted by the registrant. 

(Canis sp.) (G-30033) red. heart to brain weight; Geigy, 

13-week normocytic/nonnochromic 1992 

Feeding anemia, paroxysmal atrial 

fibrillation and right atrial 

wall hemorrhagic 

inflammation with 

angiomatous hyperplasia 

Dog -Beagle 98.7 NOAEL 5 1 of 8 females had tremors 4 13924-0 1 Minimum 

(Canis sp.) DACT LOAEL 100 Ciba1 -Year (G-28273) Geig~, 

Feeding 1990 

Laboratory rat 95.7 NOAEC 5 red. body weight; weight 430132-09 Acceptable- 

(Rattus DEA LOAEC 25 gain and food consump. Ciba- Guideline 

nowegicus) (G-30033) Development: Geigy, 

Dosed on NOAEL 25 Fused stemebrae 1 & 2 1992 

Days 6-15 LOAEC 100 Poor ossification of digit 5 

Laboratory rat 98.2 NOAEL 500 red. body weight gain and 4 13924-02 Minimum 

(Rattus DACT LOAEL 3000 food consumption Cibanonegicus) (G-28273) Geigy, 

Dosed on Development: 1989 

Days 6- 15 NOAEL 50 incr. resorption of embryos 

LOAEC 500 incr. unossified bones 

% ai 

b. Terrestrial Plants 

Tier I1 terrestrial plant toxicity studies were conducted to establish the toxicity of 

propazine to non-target terrestrial plants (MRID 441 848-04). This study was 

reevaluated in 2006 and additional statistical analyses were performed. Classification 

of the study is awaiting final EFED review. 

(PPm ai) LOAEL Endpoints 

MRID No. 

Year 

Study 

Classification 
Results of Tier I1 toxicity studies with monocots and dicots indicate that seedling 

emergence and vegetative vigor are severely impacted by exposure to propazine. 

Seedling emergence, based on shoot weight, was adversely impacted in monocots 

(onion) at an EC25 of 0.035 lb ai/A and in dicots (lettuce) with an EC25 of 0.016 lb 

ai/A (Table 111-C 18). Vegetative vigor in monocots, based on shoot weight, was 

adversely impacted in monocots (wheat) at an EC25 of 0.046 lb ai/A and in dicots 

(cucumber) at an EC25 of 0.10 lb ai/A. The observed effects to monocots and dicots 

included stunting, chlorosis, necrosis, and plant death. These values will be used to 

assess the risk of propazine to non-target terrestrial plant species. 

Terrestrial Field Studies 

Terrestrial field studies were not submitted. 
Table 111-C 18. Terrestrial Non-Target Plant T~xicity.~ 

Species I Seedling Emergence I Vegetative Vigor 

Monocots 

Corn 

Oat 

Onion 

Ryegrass 

Wheat 

Dicots 

Cabbage 

Cucumber 

Lettuce 

Radish 

Soybean 

- 

Tomato 

'MRID 441 8r 

Shoot weight 

ECzs NOAEC 

(Ib ai/A) (lb ai/A) 

>2.4 2.4 

0.050 <0.010 

0.035 <0.010 

0.83 0.077 

0.14 0.010 

0.098 <0.011 

0.12 0.077 

0.016 0.0047 

0.16 0.077 

0.97 0.59 

0.18 <0.077 

1-04, Study authors D. Schwab et a1 

Shoot length 

EC25 NOAEC 

(lb aVA) (lb aiIA) 

O/O Emergence 

EC2s NOAEC 

(lb ai/A) (lb ai1A) 

Shoot weight 

EC25 NOAEC 

Shoot length 

ECzs NOAEC 

(lb ai/A) (lb ai/A) 
IV. RISK CHARACTERIZATION 

A. Risk Estimation - Integration of Exposure and Effects Data 

Risk characterization integrates EECs and toxicity estimates and evaluates the likelihood of 

adverse ecological effects to non-target species. In a deterministic approach, an exposure 

estimate is divided by a single point estimate of toxicity (Table IV-A1) to calculate a risk 

quotient (RQ). The RQ is then compared to the Agency's levels of concern (LOCs) that serve as 

criteria for categorizing potential risk to non-target organisms (Appendix G). 

Table IV-A1. 

Taxonomic 

Group 

Birds 

Mammals 

Terrestrial 

Invertebrates 

Terrestrial Plants 

Freshwater Fish 

Freshwater 

Invertebrates 

Estuarineimarine 

Fish 

Estuarinelmarine 

Invertebrates 

Aquatic Plants 

Toxicity reference 

Assessment 

Endpoint 

Survival 

Sublethal effects 

Reproduction, 

Growth 

Survival 

Reproduction, 

Growth 

Survival 

Survival, Growth 

Survival 

. 

Reproduction, 

Growth 

Survival 

Reproduction, 

Growth 

Survival . 

Reproduction, 

Growth 

Survival 

- 

Reproduction, 

Growth 

Survival, Growth 

values used to calculate risk quotients for propazine 

Measure of Effect 

Bobwhite quail LDS0 = >I 640 mg aiikg bw; NOAEL= 244 mg ailkg bw. 

LCSo = >4930 ppm ai; NOAEL not detennined. (MRID 442873-01) 

No data submitted 

Rat LDjo = >5050 mglkgiday (MRID 434741-01) 

Rat NOAEL = 5 mgikglday, LOAEL = 50 mglkglday 

(MRID 00041 4-09) 

Honey bee: 96 hours: 2.5% mortality at 96.7 pghee 

Seedling emergence onion ECzj = 0.035 Ib ai/A; NOAEC <0.010 Ib ai/A 

Seedling emergence lettuce EC2, = 0.016 Ib ai1A; NOAEC <0.0047 Ib ai/A 

Vegetative vigor wheat ECzj = 0.046 Ib ailA; NOAEC <0.020 Ib ailA 

Vegetative vigor cucumber EC2, = 0.10 Ib ai1A; NOAEC <0.075 Ib ailA 

(MRI D 441 848-04) 

No valid studies available 

Fathead minnow NOAEC = 0.72 mg ailL (MRID 442873-07) 

Water flea ECjo = >5.32 ppm ai; NOAEC = 5.32 ppm ai (MRID 442873-05) 

Water flea NOAEC = 0.047 ppm ai; LOAEC = 0.091 ppm ai (MRID 443276-02) 

No data submitted 

Sheepshead minnow NOAEC = 1.34 mg ailL; LOAEC = 2.59 mg ailL (MRID 

44 1848-02) 

Saltwater mysid LCjo = 4.20 ppm ai; NOAEC = 0.586 ppm ai (MRID 441 848-01) 

Saltwater rnysid NOAEC = 0.269 ppm ai; LOAEC = 0.706 ppm ai (MRID 441 848- 

03) 

Diatom ECjo = 0.0248 ppm ai; NOAEC = 0.0065 ppm ai (MRID 442873-10). 

Duckweed ECS0 = 0. I0 ppm ai; NOAEC = 0.022 ppm ai (MRID 442873-09). 
1. Non-target Aquatic Animals and Plants 

a. Fish and Invertebrates 

Acute Risks 

A comparison of estimated peak propazine concentrations in surface water following 

application to sorghum to the acute toxicity values (LC50/EC50~) for freshwater and 

marinelestuarine invertebrates is provided in Table IV-A2. Acute risk quotients were 

not calculated for freshwater or estuarinelrnarine fish due to the lack of acute toxicity 

information. Acute risk quotients (RQs) for estuarinelmarine invertebrates are less 

than the Level of Concern (LOC), indicating adverse effects are not expected. Acute 

risk quotients for freshwater invertebrates were not calculated because the acute ECS0 

value for freshwater invertebrates is greater than the highest concentration tested. A 

qualitative discussion of the risk to freshwater invertebrates based on this study will 

be provided in the Risk Description section. 

Table IV-A2. Summarized Acute Risks for Aquatic Organisms a'b 

Scenario Freshwater Freshwater EstuarineiMarine EstuarineIMarine 

(1.2 lbs a.i./A) Peak EEC (ppb) Fish Invertebrate Fish invertebrated 

JSorghum in Kansas I 

erial App. 53.9 NAc Not estimated NA 0.01 

40.8 Not estimated <0.01 

erial App. 89.8 NA Not estimated NA 0.02 

I~round App 82.0 Not estimated 0.02 I 

" Detailed calculations of PRZM 3.121EXAMS 2.98 modeling are provided in Appendix C. -. . - Acute toxicity threshold (LCSo) was 4.2 ppln for estuarineln~arine invertebrates. 

' There are no valid acute toxicity studies for freshwater and estuarinelmarine fish; thus, RQ's were not calculated. RQs were not 

calculated for freshwater invertebrates because the ECso is greater than the highest concentration tested. 

Acute aquatic LOCs: acute endangered species 0.05, acute restricted use 0.1, acute non-listed species 0.5 

Chronic Risks 

The aquatic chronic LOC of 1 is exceeded for freshwater invertebrates based on the 

2 1 -day average EEC for the sorghum crop scenarios in Kansas and Texas. All other 

chronic RQs for freshwater and estuarinelrnarine fish as well as estuarinelrnarine 

invertebrates are below the chronic LOC of 1 (Table IV-A3). Chronic risk to aquatic 

invertebrates is discussed further in the Risk Description section. 
b. Aquatic Plants 

Table IV-A3. Summarized Chronic Risks for Aquatic Organisms 

For propazine, there are exceedances of the LOC for listed vascular and non-vascular 

aquatic plants exposed to runoff7drift fiom ground and aerial spray applications to 

sorghum (Table IV-A4). There are no exceedances of the LOC for unlisted vascular 

aquatic plants for the Kansas and Texas scenarios; however, there are exceedances of 

the LOC for unlisted non-vascular aquatic plants. Risk to aquatic plants will be 

discussed further in the Risk Description section. 

Scenario 

(1.2 lbs a.i.1A) 

Sorghum in Kansas 

Aerial App. 

Ground App. 

Sorghum in Texas 

Aerial App. 

Ground App. 

a Detailed calculations of PRZM 3.121EXAMS 2.98 modeling are provided in Appendix C. 

Chronic toxicity thresholds were NOAEC of 0.72 ppm for freshwater fish and NOAEC of 0.047 ppm for freshwater 

invertebrate. Estuarinel~narine fish NOEAC was 1.34 ppm and invertebrate NOAEC was 0.269 ppm. 

RQ calculation based on 60-day EEC for fish and 21-day EEC for invertebrates. 

*RQ exceeds the chronic risk LOC of 1.0 

2 1/60 Day EECs (ppb) 

53.2152.0 

40.2139.5 

88.1i85.1 

80.4177.6 

Table IV-A4. Summarized Acute Aquatic Plant Risk Quotients a.b.c.d 

. . b* RQ exceeds the Endangered Species LOC; RQ ; I .o. 

'** RQ exceeds the aquatic plant risk LOC; RQ > 1 .O. 

The endangered toxicity threshold (NOAEC) was 0.022 ppm for vascular plants and 0.0065 for non-vascular plants; acute 

toxicity thresholds (ECSo) were 0.10 ppm (MRID 442873-09) and 0.0248 ppm ( 442873-10) for vascular and freshwater nonvascular plants, respectively. 

Ground App. I 82.0 

2. Non-target Terrestrial Animals 

a. Birds 

Freshwater 

Fish 

0.07 

0.05 

0.12 

0.1 1 

Non-endangered 

Vascular Non-vascular 

0.54 2.17** 

0.4 1 1.65** 

0.90 3.62"" 

Scenario 

(1.2 Ibs a.i./A) 

Acute Risks 

Acute avian RQs were not calculated with either the oral gavage study or the subacute 

dietary study with bobwhite quail because the LD/LC50 values are greater than the 

highest dose/concentration tested. A qualitative discussion of the acute risk to birds, 

reptiles, and terrestrial-phase amphibians will be provided in the risk description. 

"Detailed calculations of PRZMIEXAMS modeling is vrovided in Avvendix C. 

3.72* 

Freshwater 

Invertebrate 

1.13* 

0.86 

1.87* 

1.71* 

Peak EEC (PP~) 

12.62* 

EstuarineiMarine 

Fish 

0.04 

0.03 

0.06 

0.06 

Endangered 

vascular 

Sorghum in Kansas 

Aerial App. 

Ground App. 

Sorghum in Texas 

Aerial App. 

0.82 3.31** 

EstuarinelMarine 

Invertebrate 

0.20 

0.15 

0.33 

0.30 

Endangered 

Non-vascular 

2.45" 

1.85* 

4.08* 

53.9 

40.8 

89.8 

8.29" 

6.28* 

13.82" 
Chronic Risks 

Chronic risks to birds were not assessed due to the lack of avian chronic toxicity 

studies. 

b. Mammals 

Acute Risks 

The acute RQs for mammals were not calculated because the LDso value obtained 

from the acute oral study is greater than the highest dose tested. A qualitative 

discussion of acute risk to mammals will be provided in the risk description. 

Chronic Risks 

To evaluate the chronic risk to mammals, RQs were calculated using the rat 

reproductive NOAEL of 5 mg/kg bw and NOAEC of 100 ppm. The RQs are detailed 

in Table IV-A5 and are summarized in Appendix D. Assuming maximum and mean 

residue levels at the maximum single application rate (1.2 lbs a.i./A for sorghum), the 

chronic dose-based risk quotients exceed the chronic LOC for mammals for the 15 g, 

35 g, and 1000g mammal weight classes consuming short grass, tall grass and 

broadleaf foragelsmall insects. The 15g and 35g mammal RQs exceed the chronic 

LOC when consuming the maximum predicted propazine residue on fruitllarge 

insects. The chronic LOC for all weight classes of mammals consuming seedslpods 

was not exceeded. At the maximum residue levels, the chronic dietary-based RQs 

exceed the chronic LOC for all food categories except fruit, large insects, seeds and 

pods. The chronic dietary-based RQ exceeds the chronic LOC for mammals 

consuming short grass using mean residues levels. Chronic risk to mammals is 

discussed further in the Risk Description section. 

Table IV-AS. Mammalian Chronic Risk Quotient Summary 

Food type 

Short grass 

Tall grass - 

Broadleaf 

forage, small 

insects 

Fruit, large 

insects 

Weight class (g) 

15 

3 5 

1000 

15 

35 

Seeds, pods 

1000 

15 

35 

1000 

15 

35 

1000 

15 

RQs for 1.2 Ibs a.i./A 

21.34" 

11.44" 

11.45* 

9.78" 

aChronic reproductive toxicity NOAEL = 5 mglkg bwlday; NOAEC = 100 ppm. 

Detailed calculations of the T-REX model (Ver. 1.2.3) and Chronic RQs are provided in Appendix D. 

* RQ exceeds the Chronic Risk LOC; RQ > 1 .O. 

3 5 

1000 

Predicted maximum residues 

Dose-Based RQs I Dietary-Based RQs 

24.99* 

5.24* 

14.06* 

12.01* 

6.44" 

1.56* 

1.33* 

0.72 

0.35 

Predicted mean residues 

Dose-Based RQs I Dietary-Based RQs 

8-82" 

2.88* 

1.32* 

0.30 

0.16 

1.62* 

0.18 

0.14 

0.07 

7.57* 

3.98* 

3.73" 

3.21* 

1.02* 

0.43 

1.68* 

4.67* 

4.01" 

2.11" 

0.73 

0.62 

0.33 

0.16 

0.54 

0.08 
c. Non-Target Terrestrial-phase Amphibians, Reptiles and Beneficial Invertebrates 

EFED currently uses surrogate data (birds) for terrestrial non-target amphibians and 

reptiles and does not quantify risks to terrestrial non-target insects. Risks are 

qualitatively discussed in the Risk Description section of this document. 

3. Non-target Terrestrial Plants in Terrestrial and Semi-aquatic Environments 

Table IV-A6 presents terrestrial plant RQs based on propazine use on sorghum for both 

ground and aerial spray applications. For the terrestrial use of propazine and the 

maximum application rate of 1.2 lbs a.i./A from aerial spray application, the acute LOC is - - - . -- 

exceeded for nonendangered monocots and dicots located in adjacent areas and in semiaquatic areas primarily as the result of runoff; and for nonendangered monocots as a 

result of spray drift (Table IV-A6). Likewise, the acute LOC is exceeded for monocots in 

semi-aquatic areas and dicots in adjacent and semi-aquatic areas primarily as the result of 

runoff from ground spray applications. RQs are higher for aerial-applications when 

compared to ground applications. This would be expected given the percentages of drift 

assumptions of 5% and 1 % for aerial and ground sprays, respectively. 

For both ground and aerial spray application, the LOC is exceeded for endangered 

monocots and dicots located in adjacent and semi-aquatic areas (Table IV-A6). The LOC 

for endangered species is exceeded for monocots and dicots in dry areas exposed to spray 

drift from both ground and aerial applications. 

I Table lV-A6. Terrestrial Plant Risk Quotient Summary for Terrestrial Spray Use on Sorghum a'b'c'd I 

- . - - - . . -. - . -. . -. . . - - . . . - . . 

Monocot I 0.69 I 3.77** I 0.34 I >2.40* 1 >13.20* 1 >1.20* 

Dicot I 1 .SO** 8.25** 0.75 5.11* I 28.09* I 2.55 

Scenario 

Sorghum (1.2 lbs a.i./A) 

Aerial spray application 

Monocot I 2.06** I 5.14** I 1.71** I 6.72" I 13.20* I 6.00* 

Dicot I 4.50** 1 11.25** 1 3.75** 14.30" 28.09* 12.77* 

a Detailed calculations for RQs and TerrPlant Ver. I .O input and output are provided in Appendix E. 

Non-endangered toxicity thresholds (EC25) were 0.035,0.016,0.046, and 0.10 Ib a.i./A for seedling emergence monocot, 

seedling emergence dicot, vegetative vigor monocot, and vegetative vigor dicot, respectively. 

' Endangered toxicity thresholds (NOAEC) were <0.01, 0.0047,0.02, and c0.075 Ib a.i./A for seedling emergence monocot, 

seedling emergence dicot, vegetative vigor monocot, and vegetative vigor dicot, respectively. 

d* RQ exceeds the Endangered Species LOC; RQ >I .O. 

** RQ exceeds the Acute Risk LOC; RQ >I .O. 

Sorehum (1.2 lbs a.i./A) 

Endangered RQs 

Terrestrial Semi-aquatic 

Adjacent area I Adjacent area I Drift 

Non-endangered RQs 

Terrestrial 

Adjacent area 

Semi-aquatic 

Adjacent area Drift 
B. Risk Description 

The risk hypothesis states that the use of propazine for weed control in sorghum has the potential 

to compromise survivorship, reproduction, andlor growth of non-target aquatic and terrestrial 

animals and plants, including Federally-listed endangered and threatened species. Based on the 

available ecotoxicity data and predicted environmental exposures, this ecological risk assessment 

supports the presumption of chronic risk to freshwater invertebrates and mammals and risk to 

non-vascular unlisted aquatic plants and to non-target terrestrial monocots and dicots following 

aerial and ground applications. This ecological risk assessment also supports the presumption of 

acute endangered species risk to vascular aquatic plants and non-target terrestrial monocots and 

dicots. The presumption of acute risk to aquatic invertebrates, mammals and birds; chronic risk 

to estuarinelmarine invertebrates and freshwater and estuarinelmarine fish; and risk to nonendangered aquatic vascular plants is not supported by the results of this screening risk 

assessment. The presumption of acute risk to freshwater and estuarinelmarine fish and chronic 

risk to birds could not be determined in this risk assessment due to the lack of usable toxicity 

data. As noted above, propazine may not be applied to selected soils and as such the risk 

conclusions do not apply to locations where sorghum is grown on these soils. More details on 

the risk conclusions can be found in the Executive Summary of the Ecological Risk Science 

Chapter for propazine. 

1. Risks to Aquatic Organisms 

In the conceptual model, spray drift and surface runofflleaching to adjacent bodies of 

water were predicted as the most likely sources of exposure of propazine to nontarget 

aquatic organisms. Risks to aquatic organisms (i.e. fish, invertebrates, and plants) were 

assessed based on modeled estimated environmental concentrations (EECs) and available 

toxicity data. Aquatic EECs for the ecological exposure to propazine were estimated 

using PRZMIEXAMS employing the standard field pond scenario (Table 11-B3). 

a. Animals 

Fish and Invertebrates 

Table IV-B1 provides a comparison of the peak EECs in surface water to acute 

toxicity values for freshwater (FW) and estuarinelmarine (EIM) fish and 

invertebrates. Toxicity studies demonstrate that propazine is moderately toxic to 

estuarinelrnarine invertebrates following acute exposure; however, at the peak EECs, 

there were no exceedances of the Acute Risk, Acute Restricted Use, or Acute 

Endangered Species LOCs for estuarinelrnarine invertebrates (Table IV-A2). In a 48- 

hour flow-through test with freshwater daphnids, no immobilization or sublethal 

effects were observed at the highest test concentration, resulting in an ECSo of >5.32 

ppm ai (mean measured concentration) (MRID 442873-05). The study is 

scientifically sound but does not fulfill guideline requirements because daphnids were 

not exposed up to 100 ppm ai. Consequently, the acute toxicity of propazine to 

freshwater invertebrates cannot be categorized. If it can be shown that the test was 

conducted up to the limit of solubility, the study could be upgraded to acceptable. 

However, for these requested uses, a comparison of the highest concentration tested 
in the daphnid study (5320 ppb) with the highest peak EEC of 89.8 ppb shows that 

there were no effects in daphnids at concentrations 59 times higher than the highest 

peak EEC. Therefore, potential acute risk to freshwater invertebrates is expected to 

be minimal. Toxicity data are unavailable for freshwater and estuarinelmarine fish; 

consequently, the acute risk for these taxonomic groups following exposure to 

propazine under the proposed labeled uses remains an uncertainty. 

Table IV-B2 provides a comparison of the 2 1 - and 60-day EECs in surface water to 

chronic toxicity values for freshwater (FW) and estuarinelmarine (EIM) invertebrates 

and fish, respectively. Chronic exposure of propazine to estuarinelrnarine 

invertebrates produced significant effects to reproduction in mysid shrimp at 0.706 

ppm ai. However, at the 2 1 -day EEC, the chronic LOC for estuarinelmarine 

invertebrates was not exceeded (Table IV-A3). Chronic exposure of propazine to 

fathead minnows resulted in significant reductions in length at 1.14 mg ai1L and 

chronic exposure to sheepshead minnow affected embryo survival and hatching 

success at 2.59 mg ai1L. However, at the 60-day EEC, there were no exceedances of 

the aquatic chronic LOC for freshwater and estuarinelmarine fish (Table IV-A3). 

Table IV-B 1. Comparison of Peak EECs of Propazine in Surface Water to Aquatic Acute Toxicity Values 

Chronic exposure of propazine to freshwater invertebrates produced adverse effects to 

growth at 0.091 ppm ai. Risk quotients for freshwater invertebrates exceeded the 

chronic LOC (Table IV-A3) when propazine is applied to sorghum and it is assumed 

that it reaches the surface water by runoff andlor leaching at the predicted 

PRZMIEXAMS EECs. Consequently, freshwater invertebrates inhabiting surface 

waters adjacent to a propazine treated field would be at risk for adverse effects on 

survival and growth following chronic exposure to propazine in surface runoff andlor 

leachate as a result of spray application at the 2 1 -day average EEC for the Kansas and 

Texas sorghum crop scenarios. Daphnids play a critical role in aquatic food webs by 

serving as an intermediate between primary producers and fish. Consequently, changes 

in daphnid populations, either through direct mortality or sublethal (e.g. reproductive, 

growth) effects, could trigger community- or ecosystem-level responses. When 

propazine is applied aerially to sorghum, the predicted aquatic exposure js 53.2 pg/L 

for the Kansas scenario and the NOAEC for the daphnid is 47pg/L, indicating that the 

chronic LOC for freshwater invertebrates at the application rate of 1.2 lb ai/A is only 

slightly exceeded for the Kansas scenario. However, when propazine is applied by 

either aerial or ground spray to sorghum in the Texas scenario, the EEC's are 

Simulation Scenario . . . . . . . . - - . - - -. . . . -. .- - - .. . - 

Sorghum 

(1.2 Ib a.i./A) 

Sorghum (KS) 

Aerial spray 

Ground spray 

Sorghum (TX) 

Aerial spray 

Ground spray 

. . . . . . . -. .- _. . E EC's (pg"!). . . . . - - - - -. . . Toxicity Values (pgIL) 

Peak 

53.9 

40.8 

89.8 

82.0 

. . - - _ - - _ - - -. -. - - - 

FW 

Invertebrate 

ECS0 

5,320 

21-day 

53.2 

40.2 

88.1 

80.4 

- - - - . . . - - - - - - - 

E/M 

Invertebrate 

LCs0 

4,200 

60-day 

52.0 

39.5 

85.1 

77.6 

- - - - - - -. -. . - - - 

FW & EM 

Fish 

N/A 
approximately 1.8 1 times the NOAEC for the sensitive freshwater daphnid. Keeping 

all parameters in the modeling scenarios the same and assuming that EECs are reduced 

linearly with application rate reduction, EFED conducted an analysis of the effect of 

rate reduction on chronic RQs for aquatic invertebrates. The chronic RQs for sorghum 

grown in Texas may be reduced to below the chronic LOC of 1.0 if the application rates 

are reduced by 45% to 0.66 lb ai/A. 

RQ exceeded LOC. 

Table IV-B 2. Comparison of 21- and 60-day EECs of Propazine in Surface Water to 

Aquatic Chronic Toxicity Values. 

b. Aquatic Plants 

Simulation Scenario .------------------~-~~~~~~.~~~~~~~~~~~~. 

Sorghum 

(1.2 Ib a.i./A) 

In aquatic plants, propazine produces adverse effects to growth and cell density in 

both vascular and nonvascular plants. In the duckweed study, an ECso of 0.010 ppm 

a.i. (NOAEC of 0.022 ppm a.i) was determined. Algal ECS0 values ranged from 0.18 

to 0.029 ppm ai. The fi-eshwater diatom, Navicula pelliculosa, was the most sensitive 

nonvascular aquatic plant, with an NOAEC of 0.0065 ppm ai. For the use scenario 

modeled for propazine, there are exceedances of the endangered LOCs for both 

vascular and non-vascular aquatic plants for runoffldrift from ground and aerial spray 

applications to sorghum (Table IV-A4). There were no exceedances of the LOC for 

non-listed vascular aquatic plants for the Kansas and Texas scenarios; however, there 

were exceedances of the LOC for unlisted non-vascular aquatic plants (Table IV-A4), 

assuming that the maximum predicted propazine concentrations would come in 

contact with freshwater nonvascular plants. Consequently, both listed vascular and 

non-vascular plants and unlisted nonvascular plants inhabiting surface waters 

adjacent to a treated field would be at risk for adverse effects to growth and 

development when exposed to propazine as a result of the labeled use on sorghum. 

Although there are no listed nonvascular plants, there is concern for indirect effects to 

other taxa as these aquatic plants are a basis for food and other needs. The RQs for 

"endangered" nonvascular plants range from 0.61 for blue-green algae (Kansas, 

ground application) to 13.37 (Texas, aerial application) for diatoms. 

Table IV-B3 provides a comparison of the peak EECs in surface water to toxicity 

values for both listed and unlisted vascular and nonvascular aquatic plants for risks 

associated with exposure of aquatic plants to propazine by surface runoff andlor 

leaching. Keeping all parameters in the modeling scenarios the same and assuming 

that EECs are reduced linearly with application rate reduction, EFED conducted an 

Sorghum (KS) 

Aerial spray 53.2 52.0 

Ground spray 40.2 39.5 

Sorghum (TX) 

Aerial spray 88.1 85.1 

Ground spray 80.4 77.6 

EEC's.(l?g'!!). . . - -. Toxicity Values (pg/L)_ 

21-day . . . . . . . . -. - - - - - - - - 

FW 

Invertebrate 

NOAEC 

47* 269 720 

60-day 

1,340 

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

E/M 

Invertebrate 

NOAEC 

- -. -. - - -. - 

FW Fish 

NOAEC 

-. - - - - - - - - - - - - - _. 

EM Fish 

NOAEC 
analysis of the effect of rate reduction on RQs for aquatic plants. The RQs for the 

aerial spray to sorghum in the Kansas scenario may be reduced to below the aquatic 

plant LOC (1 .O) if the application rates are reduced by 87% to 0.16 lb ai/A. The RQs 

for the aerial spray to sorghum in the Texas scenario may be reduced to below the 

aquatic plant LOC (1 .O) if the application rates are reduced by 93% to 0.08 lb ai/A. A 

complete spray drift analysis for exposures to aquatic plants is provided in Section 

IV.B.3. The potential risk to endangered vascular aquatic plants will be discussed in 

greater detail in Section IV.B.6. 

RQ's exceeded LOC's. 

Table IV-B 3. Comparison of Peak EECs of Propazine in Surface Water to Aquatic Plant Toxicity Values. 

2. Risks to Terrestrial Organisms 

Simulation scenario ----------------.-------.-.-----.-....- 

Sorghum 

(1.2 Ib a.i./A) 

In the conceptual model, ground deposition from spray application and spray drift with 

resulting residues on foliage and on flowers and seeds are the most likely sources of 

propazine exposure to nontarget terrestrial organisms, including listed species. Risks to 

terrestrial organisms (i.e. birds, mammals, and plants) were assessed based on modeled 

EECs and available toxicity data. As part of the terrestrial assessment, exposure 

concentrations of propazine to nontarget terrestrial plants and animals were modeled 

according to the labeled application rate for sorghum. For terrestrial birds and mammals, 

estimates of initial levels of propazine residues on various food items, which may be 

contacted or consumed by wildlife, were determined using the Fletcher nomogram 

followed by a first order decline model TREX 1.2.3. Likewise, the TerrPlant 1.0 model 

was used to estimate exposure to nontarget plants and the AgDrift 2.0.1 model provided 

further refinement of spray drift dispersion and deposition to terrestrial plants located in 

proximity to treated fields. 

a. Animals 

EEC's (~!m - -. 

Peak 

Birds, Reptiles and Terrestrial-phase Amphibians 

Propazine is categorized as at most, slightly toxic to upland game birds (bobwhite 

quail) on an acute oral basis (LDS0 >1,640 mg aikg) and subacute dietary basis (LCso 

>4,930 ppm ai). The degradate deethylatrazine is also slightly toxic to bobwhite 

quail. Propazine is practically nontoxic to waterfowl (mallard) on a subacute dietary 

basis. Reproduction studies are not available to assess the risk to upland game birds 

Sorghum (KS) 

Aerial spray 53.9 

Ground spray 40.8 

Sorghum (TX) 

Aerial spray 89.8 

Ground spray 82.0 

* 

22* 

Toxicity Values ( 

6.5* 100 24.8* 

. _- -. - - -. - - - - - - - - - - 

Endangered 

Vascular 

NOAEC 

- - - - - - - - - - - - - - - - - ;! g/L) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

Endangered 

Nonvascular 

NOAEC 

Nonendangered 

Vascular 

ECS0 

Non-endangered 

Nonvascular 

ECso 
and waterfowl from developmental/reproductive effects following chronic exposure 

to propazine under the currently proposed labeled uses. 

Acute RQs were not estimated because the LD50/LCs0'~ were higher than the highest 

dose/concentration tested. For risk description purposes, the highest 

doseiconcentration tested was compared with the expected terrestrial EECs. 

The acute oral LDS0 for bobwhite quail is >1,640 mg ai/kg body weight and the acute 

dietary LCs0 for bobwhite quail is >4930 pprn food. Assuming the maximum 

application rate for sorghum and maximum predicted residue levels, the predicted 

terrestrial EECs from the T-REX model (Ver.1.2.3) may be as high as 328 mg/kg bw 

for 20 g birds on a dose basis and 288 pprn for short grass on a dietary basis. In the 

acute oral LDS0 study, there were no mortalities at 1640 mg/kg bw (weight adjusted 

value for 20 g birds is 1 181.5 mglkg bw). There is nearly a 4-fold difference between 

the EEC of 328 mglkg bw and the adjusted LDS0 of 1 181 -5 mgkg bw. Therefore, the 

risk of mortality at these EECs is low. On a dietary basis, again, there were no 

mortalities at the highest concentration tested (4930 pprn). The difference between 

the dietary concentration of 288 pprn and the LCso of 4930 pprn is more than an order 

of magnitude. Again, the potential risk of mortality to birds, reptiles and terrestrialphase amphibians on a dietary basis is likely to be minimal. 

In both the acute oral gavage and acute dietary studies, a possible chemical-induced 

anorexia occurred. Feed consumption and growth were initially affected by 

propazine at the 430 mg ailkg dose in the gavage study (MRID 442873-01). The 

study authors noted that a NOAEC could be determined to be 244 mg aikg due to 

weight loss up to 72 hours after treatment. In the dietary study with quail, diminished 

feed consumption, slow growth, and cannibalism were observed at treatments ranging 

fi-om 578 to 4,930 pprn ai (MRID 442873-02). Feed consumption rates and resultant 

growth were also affected in the dietary study with mallard ducks at all treatment 

levels (MRID 442873-03). In the dietary studies, the study authors could attribute the 

effects to food avoidance; however, in the oral study, the dose-related loss of weight 

was not related to dietary exposure. The authors suggested that the food avoidance 

may not just be related to feed palatability but rather result from chemically-induced 

anorexia. No treatment-related mortalities were observed in either study. In order to 

evaluate potential sublethal effects associated with acute exposure to propazine on a 

dose-related basis, the lowest dose (430 mg aikg bw - oral) producing effects 

(weight loss) are compared to predicted avian doses on food residues (EEC equivalent 

dose) following the application of propazine at 1.2 lbs ai/A. Table IV-B5 summarizes 

this comparison. For the use of propazine on sorghum with spray applications of 1.2 

Ibs aiIA, the highest EEC equivalent dose is 328 mg aikg-bw for short grass 

consumed by a 20g bird. The adjusted LOAEL for 20g birds is 3 10 mg aiikg-bw. 

Therefore, at the predicted EEC for short grass, weight loss may be expected, 

indicating that there may be risks to acute sublethal effects in birds, reptiles and 

terrestrial-phase amphibians following spray applications. 
I Table IV-B 4. Comparison of Avian Sublethal Values with Predicted Doses on Food Residuesa 

I I 

short grass 

Food Type 

tall grass 

Lbroadleaf forage, small insects I 

"Acute effect levels: LOAEL: 430 mg ailkg-bw (oral); 578 ppm ai (dietary) 

Weight class (g) 

b See Appendix D for T-Rex modeling results. 

No chronic avian studies are available. Decreased body weight and food 

consumption were observed in the acute avian studies and similar effects were 

observed in the developmental and reproduction studies in mammals. It is likely that 

similar effects would also be observed in the avian reproduction studies. This 

1.2 lbs a.i./A 

increases the uncertainty of risk to birds, reptiles and terrestrial phase amphibians 

following chronic exposure. 

Predicted EEC Equivalent 

Dose (mg aiikg-bw) 

Mammals 

Propazine is classified as practically non-toxic to small mammals on an acute oral 

basis (LD50 value of >5,050 mg/kg). The degradate deethylatrazine is classified as 

slightly toxic to small mammals on an acute oral basis (LDS0 values from 668 to 

1,88 1 mg/kg). When RQs are estimated using the LDsO of >5,050 mglkg and 

assuming the maximum application rate for sorghum and maximum predicted residue 

levels; neither the Acute Risk, Acute Restricted Use, or Acute Endangered Species 

Risk LOCs were exceeded (Table IV-B6); consequently, mammals would not be at 

risk for direct effects on foraging behavior following acute exposure to propazine 

under the currently proposed labeled uses (Table IV-B6). 

Adjusted LOAEL 

(mg ailkg-bw) 

Table IV-B 5. Mammalian Acute Risk Quotient Summary a9b,c7d 

- 

Food type 

short grass 

Weight class (g) 

15 

3 5 

1.2 Ibs a.i./A 

Predicted maximum Predicted mean 

residues Residues 

0.02 0.0 1 

0.02 0.01 
Table IV-B 5. Mammalian Acute Risk Quotient Summary a,b,c,d 

1.2 lbs a.i./A 

Food type Weight .,, I Predicted maximum Predicted mean class (&, 

residues Residues 

tall grass 

seeds, pods 1000 <0.01 <0.01 

a Acute toxicity threshold was LDS0 = 5050 mglkg-bw. 

Detailed calculations of the T-REX model (Ver. 1.2.3) and Acute RQs are provided in Appendix D. 

RQs in this table were calculated for the maximum labeled application rate of 1.2 Ibs a.i./A for sorghum. 

* RQ exceeds the Endangered Species Level of Concern (LOC); RQ > 0.10. 

** RQ exceeds the Acute Restricted Use LOC; RQ > 0.20. 

*** RQ exceeds the Acute Risk LOC; RQ > 0.50. 

broadleaf forage, small insects 

fruit, large insects 

In a 3-generation reproduction study with rats, propazine produced decreased body 

weights in males and females, resulting in a parentalloffspring NOAEC of 5 

mg/kg/day. No treatment-related effects on reproduction were observed; 

consequently, the NOAEC for reproductive toxicity was 250 mgkg bwlday. In 

developmental toxicity studies, administration of propazine by gavage produced 

maternal toxicity in both Sprague-Dawley rats and New Zealand rabbits with a 

NOAEC of 10 mgkg bw/day (Table 111-C 16). Decreased ossification was also 

observed in offspring of rats, resulting in a developmental NOAEC of 10 mgkdday. 

Developmental effects were also observed for the degradates, DEA and DACT in rats 

at 100 ppm ai (fused sternebrae and poor ossification) and 500 ppm ai (embryo 

resorption and poor ossification), respectively. Based on the rat parentalloffspring 

toxicity data from the reproduction study and assuming the maximum application 

rate; the chronic LOC was exceeded for all weight classes of mammals consuming 

short grasses, tall grasses, and broadleaf foragelsmall insects at both the maximum 

and mean predicted residue levels; and for 15 and 35 g mammals consuming fruit and 

large insects at the maximum predicted residue levels (Table IVA-5). Consequently, 

1000 0.01 <0.01 

1000 

15 

35 

1000 

15 

0.01 <0.01 

<0.01 <0.01 

<o.o 1 <0.01 

cO.01 <0.01 

<0.01 <O.O 1 
there are potential risks to mammals following chronic exposure to propazine when 

used as directed on the label. 

In order to evaluate potential chronic effects associated with acute exposure to 

propazine on a dose-related basis, the adjusted NOAEL is compared to predicted 

mammalian doses on food residues (EEC equivalent dose) for all weight classes and 

food types for which chronic RQs were exceeded at the application rate 1.2 lbs ai/A. 

Table IV-B7 summarizes this comparison. The dose-based EECs range from 25 times 

(1 5 g mammals consuming short grasses) to 5 times (1 000 g mammals consuming tall 

grasses) the adjusted NOAELs. Keeping all parameters in the modeling scenarios the 

same and assuming that EECs are reduced linearly with application rate reduction, 

EFED conducted an analysis of the effect of rate reduction on chronic RQs for 

mammals. The chronic RQs for sorghum may be reduced to below the chronic LOC of 

1 .O if the application rates are reduced by 83.3% to 0.13 lb ai/A. 

I Table IV-B 6. Comparison of Mammalian Chronic Toxicity Values with Predicted Doses on Food Residuesa 

I 1 1 1.2 Ibs a.i./A 

Food type 

lbroadleaf forage, small insects1 1000 I 24.75 3.85 

'NOAEL: 5 mgkg-bwiday 

short grass 

tall grass 

Non-target Bene$cial Invertebrates 

Weight class (g) 

15 

35 

EFED currently does not quantify risks to terrestrial non-target invertebrates. In an 

acute contact study with the honey bee, propazine was determined to be relatively 

non-toxic. At 96 hours, mortality was 2.47% at a dose of 96.69 pghee (Atkins et al. 

1975). It is unlikely that there will be risks to pollinators and other beneficial insects 

at the proposed labeled rates. 

Dose-based EECs (mgtkg- Adjusted NOAEL 

bw) (mgtkg-bwtday) 

274.59 10.99 

189.78 8.89 

1000 

15 

35 

1000 

15 

44.0 3.85 

125.85 10.99 

86.98 8.89 

20.17 3.85 

154.45 10.99 
b. Terrestrial Plants 

Results of Tier I1 toxicity studies with monocots and dicots indicate that seedling 

emergence and vegetative vigor are severely impacted by exposure to propazine. 

Seedling emergence, based on shoot weight, was adversely impacted in monocots 

(onion) at an ECZ5 of 0.035 lb ai/A and in dicots (lettuce) with an EC25 of 0.016 lb 

ai/A. Vegetative vigor in monocots, based on shoot weight, was adversely impacted 

in monocots (wheat) at an EC25 of 0.046 lb ai/A and in dicots (cucumber) at an EC25 

of 0.10 lb ai/A. The observed effects to monocots and dicots included stunting, 

chlorosis, necrosis, and plant death. 

For the terrestrial use of propazine and the maximum application rate of 1.2 lbs a.i./A 

from aerial spray application, the acute risk LOC was exceeded for nonendangered 

monocots and dicots located in adjacent areas and in semi-aquatic areas primarily as a 

result of runoff; and for nonendangered monocots and dicots as a result of spray drift. 

Likewise, the acute risk LOC was exceeded for nonendangered monocots in semiaquatic areas and nonendangered dicots in adjacent and semi-aquatic areas as the 

result of runoff from ground spray applications. For both ground and aerial spray 

application, the LOC was exceeded for endangered monocots and dicots located in 

adjacent and semi-aquatic areas primarily as a result of runoff (Table IVA-6). The 

endangered species LOC was exceeded for monocots and dicots in dry areas exposed 

to spray drift from both aerial and ground applications. Consequently, 

nonendangered and endangered monocots and dicots inhabiting dry and semi-aquatic 

areas adjacent to a treated field would be at risk for adverse effects to growth and 

development when exposed to propazine as a result of the labeled uses. A complete 

spray drift analysis for exposures to non-target terrestrial plants in terrestrial and 

semi-aquatic areas is provided in Section IV.B.3. The potential risk to endangered 

monocots and dicots will be discussed in greater detail in Section IV.B.6. 

3. Spray Drift Analysis 

The AgDRIFT model (Version 2.01) was used to refine the spray drift exposure estimate for 

terrestrial plants. Downwind spray drift distances from ground and aerial applications are 

estimated for possible use in mitigating risks for endangered terrestrial plants that grow in close 

proximity to agricultural and non-agricultural fields that may be treated with propazine. The 

model was used to estimate distances (in feet) required to dissipate spray drifi to the most 

sensitive NOAEC/EC25 levels for monocot and dicot species in the seedling emergence andlor 

vegetative vigor studies. The standard toxicity level EFED uses for calculating risk quotients for 

non-endangered terrestrial plants is the EC25. For endangered plants, the NOAEC (or ECos if a 

NOAEC value is not available) is used. Seedling emergence endpoints are representative of 

exposure through soil to germinating plants, while vegetative vigor endpoints are representative 

of foliar exposure. The terrestrial plant measurement endpoints used in the model are specified 

in Table IVB-7. 
Table IVB-7. Agdrift Input Parameters for Tern 

Study Species 

Seedling Emergence: Monocot I Onion 

Seedling Emergence: Lettuce 

Dicot 

Vegetative Vigor: Wheat 

Monocot 

I Vegetative Vigor: Cucumber 

Dicot ' The fraction of the application rate = NOAEC or the 

trial Plant Measurement Endpoint 

(Ib ai/A) (Ib ai/A) / 

/Fraction Fraction 

lC25/maximum application rate of pn 

Most sensitive 

parameter 

Shoot weight 

Shoot weight 

Shoot weight 

Shoot weight 

Because the label for propazine does not specify release height or droplet size for ground 

applications, the AgDRIFT model was run for all four scenarios (high boom and fine spray, low 

boom and fine spray, high boom and medium/coarse spray, and low boom and medium/coarse 

spray) to provide a range of distances (in feet) required to dissipate spray drift to the most 

sensitive NOAEC/EC25 levels. All droplet size descriptions are based on ASAE S-572 standard 

definitions. High and low boom heights are representative of 4 and 2 foot release heights, 

respectively. AgDRIFT outputs for ground boom applications estimate the 5oth and 90" 

percentile of data collected from field trials. For this analysis, the 9oth percentile was used to 

provide protective dissipation distances. Available toxicity data indicate that the terrestrial 

plants are most sensitive to propazine via soil uptake rather than application of the herbicide 

directly to post-emergent foliage. Therefore, downwind spray drift distances based on the 

NOAEC and EC25 values derived from SE toxicity tests were utilized and are believed to be 

protective of both endangered and non-endangered terrestrial plants, respectively. 

A summary of the results of the Tier 1 AgDRIFT modeling for ground and aerial application of 

propazine are presented in Tables IVB-8 and IVB-9. The tables summarize the downwind 

distances required to dissipate spray drift for endangered species (Table IVB-8 with the NOAEC 

levels) and non-endangered species (Table IVB-9 with the EC25 values) for both monocot and 

dicot terrestrial plant species and for both ground and aerial applications of propazine. 

Modeled drift dissipation distances for endangered species, based on ground boom applications 

are expected to range from approximately >I20 to 500 feet for very fine to fine droplet sizes and 

from >46 to 200 feet for fine to medium/coarse droplet sizes (the > values are due to the NOAEC 

value of <0.01). Over the range of modeled droplet sizes, the protective spray drift distances for 

endangered monocots range from >46 to >285 feet and for endangered dicots, 120 to 500 feet. 

Modeled dissipation distances for endangered monocots and dicots, based on aerial application 

of propazine, using the default fine to medium droplet sizes are uncertain because they exceed 

the 1,000 foot limit of the model. For medium to coarse droplet sizes, the expected dissipation 

distances are again uncertain because they range from >570 to >I000 feet (again, the value of > 

570 feet is due to the NOAEC value of <0.01). 
Modeled drift dissipation distances for non-endangered species, based on ground boom 

applications are expected to range from approximately 30 to 190 feet for very fine to fine droplet - - 

sizes and from 10 to 50 feet for fine to mediumlcoarse droplet sizes. Over the range of modeled 

droplet sizes, the protective spray drift distances for monocots range from 10 to 90 feet and for 

dicots, 26 to 190 feet. Modeled dissipation distances for non-endangered monocots and dicots, 

based on aerial application of propazine, using the default fine to medium droplet sizes are 

expected to range fiom 325 to 830 feet. For medium to coarse droplet sizes, the expected 

dissipation distances range from approximately 1 80 to 34 1 feet. 

Table IVB-8. Summary of AgDRl 

Crop 

Monocots (onion) 

Low Boom (20 inches) 

High Boom (50 inches) 

Dicots (lettuce) 

Low Boom (20 inches) 

High Boom (50 inches) 

* The maximum dissipation distance 

'T Modeling Results for Endangered Plant Species 

Distance Required to Dissipate 

Spray Drift to NOAEC Levels for 

Ground Application (feet) 

Droplet Size 

>I21 1 >46 I NIA I NIA 

Distance Required to Dissipate 

Spray Drift to NOAEC Levels for 

Aerial Application (feet) 

Droplet Size 

Very Fine to 

Fine 

>285 1 >85 I NIA I NIA 

I I I 

263 I 118 I NIA I NIA 

Fine to 

MediumlCoarse 

Table IVB-9. Summary of AgDRIFT Modeling Results for Non-Endangered Plant Species 1 

Fine to Medium 

492 

Crop 

Medium to 

Coarse 

om the edge of the field in the Tier I ground model is 1,000 feet. 

200 

I Droplet Size I Droplet Size I 

Distance Required to Dissipate 

Spray Drift to ECZs Levels for 

Ground Application (feet) 

NIA 

- 

Distance Required to Dissipate 

Spray Drift to ECZs Levels for 

Aerial Application (feet) 

NIA 

Very Fine to 

Fine 

Monocots (onion) 

High Boom (50 inches) I 8 9 I 20 I NIA I NIA 1 

Fine to 

MediumlCoarse 

Low Boom (20 inches) 

Dicots (lettuce) 1 1 1 830 1 341 1 

I I I I 

325 

Low Boom (20 inches) I 72 I 2 6 I NIA NIA 

Fine to Medium 

180 

I 33 NIA 

Medium to 

Coarse 

10 

High Boom (50 inches) 

NIA 

"he maximum dissipation distance from the edge of the field in the Tier I ground model is 1,000 feet. 

187 46 NIA NI A 
The current label provides appropriate information on spray drift management to guide the 

applicator while providing few specific requirements for minimizing spray drift. Given that 

some of the predicted spray drift distances are large, that there are associated uncertainties for 

aerial application of propazine and the fact that the NOAEC for monocots is not defined (i.e., it 

is a < value), if mitigation of risk is desired, then it is recommended that the label language for 

spray drift require specific spray drift mitigation measures (i.e., lower release heights, wind 

speed restrictions, and specification of spray droplet sizes). 

4. Review of Incident Data 

Incident reports submitted to EPA since approximately 1994 have been tracked by 

assignment of EIIS (Environmental Incident Information System) in an Incident Data 

System (IDS). There are no incident reports for propazine. 

5. Endocrine Effects 

In March 2002, based on the available weight-of-evidence, the Agency's Health Effects 

Division (HED) determined that atrazine, simazine, propazine, and their degradates, 

DEA, DIA, and DACT can be grouped by a common mechanism of toxicity for 

neuroendocrine effects (disruption of the hypothalamic-pituitary-gonadal (HPG) axis). 

Based on these effects in mammals and endocrine effects in other taxonomic groups with 

the above triazine-containing pesticides and degradates, propazine and its degradates may 

be classified as potential endocrine disruptors. EPA is required under the Federal Food, 

Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act 

(FQPA), to develop a screening program to determine whether certain substances 

(including all pesticide active and other ingredients) "may have an effect in humans that 

is similar to an erect produced by a naturally occurring estrogen, or other such 

endocrine effects as the Administrator may designate." Following the recommendations 

of its Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC), EPA 

determined that there was a scientific basis for including, as part of the program, the 

androgen and thyroid hormone systems, in addition to the estrogen hormone system. 

EPA also adopted EDSTAC's recommendation that the Program include evaluations of 

potential effects in wildlife. For pesticide chemicals, EPA will use the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) and, to the extent that effects in 

wildlife may help determine whether a substance may have an effect in humans, FFDCA 

authority to require the wildlife evaluations. As the science develops and resources 

allow, screening of additional hormone systems may be added to the Endocrine Disruptor 

Screening Program (EDSP). When the appropriate screening and/or testing protocols 

being considered under the Agency's EDSP have been developed, propazine may be 

subjected to additional screening and/or testing to better characterize effects related to 

endocrine disruption. 
6. Federally Threatened and Endangered (Listed) Species Concerns 

a. Action Area 

For listed species assessment purposes, the action area is considered to be the area 

affected directly or indirectly by the Federal action and not merely the immediate area 

involved in the action. At the initial screening-level, the risk assessment considers 

broadly described taxonomic groups and conservatively assumes that listed species 

within those broad groups are co-located with the pesticide treatment area. This 

means that terrestrial plants and wildlife are assumed to be located on or adjacent to 

the treated site and aquatic organisms are assumed to be located in a surface water 

body adjacent to the treated site. The assessment also assumes that the listed species 

are located within an assumed area which has the relatively highest potential exposure 

to the pesticide, and that exposures are likely to decrease with distance from the 

treatment area. Section II.A.4 of this risk assessment presents the pesticide use sites 

that are used to establish initial collocation of species with treatment areas. 

If the assumptions associated with the screening-level action area result in RQs that 

are below the listed species LOCs, a "no effect" determination conclusion is made 

with respect to listed species in that taxa, and no further refinement of the action area 

is necessary. Furthermore, RQs below the listed species LOCs for a given taxonomic 

group indicate no concern for indirect effects upon listed species that depend upon the 

taxonomic group covered by the RQ as a resource. However, in situations where the 

screening assumptions lead to RQs in excess of the listed species LOCs for a given 

taxonomic group, a potential for a "may affect" conclusion exists and may be 

associated with direct effects on listed species belonging to that taxonomic group or 

may extend to indirect effects upon listed species that depend upon that taxonomic 

group as a resource. In such cases, additional information on the biology of listed 

species, the locations of these species, and the locations of use sites and could be 

considered along with available information on the fate and transport properties of the 

pesticide to determine the extent to which screening assumptions regarding an action 

area apply to a particular listed organism. These subsequent refinement steps could 

consider how this information would impact the action area for a particular listed 

organism and may potentially include areas of exposure that are downwind and 

downstream of the pesticide use site. 

For this risk assessment for propazine, a "no effect" determination cannot be made for 

any species because both aquatic and terrestrial plants are affected by propazine under 

the proposed uses and all other species may be indirectly affected fi-om effects to 

aquatic andlor terrestrial plants. 

b. Taxonomic Groups Potentially at Risk 

The preliminary risk assessment for endangered species indicates that propazine 

exceeds the Endangered Species LOCs for the specified use scenario for the 

following taxonomic groups: 
aquatic vascular plants at the maximum application rate by ground and aerial 

spray application, 

aquatic non-vascular plants at the maximum application rate by ground and aerial 

spray application (although none are listed as endangered, there may be concerns 

for other taxa with obligate relationships with these species), 

non-target terrestrial plants - endangered monocots and dicots adjacent to treated 

areas and in semi-aquatic areas at the application rate by ground and aerial spray 

application; endangered monocots and dicots in dry areas exposed to spray drift 

by both aerial and ground application at the application rate, 

Listed mammals (chronic exposure) at the maximum application rate by ground 

and aerial spray application, 

Listed freshwater invertebrates (chronic exposure) at the maximum application 

rate by ground and aerial spray application, 

AgDrift model predicts LOC exceedances for listed plant species at distances of 

more than 1000 feet for aerial application and up to 148 feet for ground 

applications from the edge of the field, 

AgDrift model predicts exceedances of LOC for listed terrestrial plant species 

inhabiting ponds and wetlands exposed from spray drift due to agricultural use at 

distances up to 100 feet from areas treated via aerial applications. Likewise, the 

model predicts LOC exceedances for listed aquatic plants inhabiting wetlands 

exposed from spray drift at distances of zero up to 62 feet from treated areas as 

the result of aerial spray applications. 

Table IVB-I 0 summarizes the listed species at risk associated with either direct or indirect 

effects following application of propazine at the requested rates. 

Concerns For Federally Listed as Endangered and/or Threatened Species 

Table IVB-10. Listed species risks associated with direct or indirect effects due to applications of propazine on 

sorghum 

Listed Taxon 

Terrestrial and semi-aquatic plants - monocots 

Terrestrial and semi-aquatic plants - dicots 

Terrestrial invertebrates 

Birds 

Terrestrial-phase amphibians 

Direct Effects 

Yes 

Yes 

No for terrestrial insects; 

unknown for other terrestrial 

invertabrates (insufficient data) 

Possible: no chronic avian data; 

sublethal effects in acute studies 

coupled with similar effects in 

mammalian reproduction study 

increase uncertainty for birds. 

Possible: no acute or chronic 

data and no chronic avian data 

Indirect Effects 

Yes through effects to pollinators 

(mammals; uncertain with birds, 

reptiles, terrestrial-phase 

amphibians) 

Yes through effects to pollinators 

(mammals; uncertain with birds, 

reptiles, terrestrial-phase 

amphibians) 

Yes through effects to terrestrial 

and aquatic plants (food and 

habitat) 

Yes through effects to terrestrial 

and aquatic plants (food and 

habitat), mammals, freshwater 

invertebrates) 

Yes through effects to terrestrial 

and aquatic plants (food and 
I Table IVB-10. Listed species risks associated with direct or indirect effects due to applications of propazine on I 

I invertebrates) 

Reptiles I Possible: no acute or chronic I Yes through effects to terrestrial 

Listed Taxon 

Aquatic-phase amphibians 

(see comment for birds) I habitat), mammals, freshwater 

Direct Effects 

Mammals 

Aquatic non-vascular plants* 

Aquatic vascular plants 

Freshwater fish 

Indirect Effects 

data and no chronic avian data 

(see comment for birds) 

Yes with chronic exposure. 

Yes 

Yes 

Unknown with acute exposure 

(no acute data); No after chronic 

exposure. 

Unknown with acute exposure 

(no acute data); using chronic 

data on fish as surrogate - No 

and aquatic plants (food and 

habitat), mammals, freshwater 

invertebrates) 

Yes through effects to terrestrial 

and aquatic plants, mammals, 

freshwater invertebrates. 

No 

No 

Yes through effects to terrestrial 

plants (stream quality), aquatic 

plants (food and habitat) and 

freshwater invertebrates (food) 

Yes through effects to terrestrial 

plants (stream quality), aquatic 

plants (food and habitat) and 

Freshwater crustaceans 

Mollusks 

surrogate - No after acute 

exposure and Yes after chronic 

exposure. 

- 

after chronic exposure. 

Using data on daphnia as 

plants (stream quality), aquatic 

plants (food and habitat) and 

other freshwater invertebrates 

freshwater invertebrates (food) 

Yes through effects to terrestrial 

No after acute exposure; Using 

chronic data on crustaceans as 

surrogate - NO after chronic 

Yes through effects to terrestrial 

plants (stream quality) and 

aquatic plants (food and habitat). 

Marinelestuarine fish 

invertebrates (food) 

Vt the present time no aquatic non-vascular plants are included in Federal listings of threatened and endangered species. The 

Marinelestuarine crustaceans 

taxono~nic group is included here for the purposes of evaluating potential contributions to indirect effects to bther taxa and as a 

record of exceedences should future listings of non-vascular aquatic plants warrant additional evaluation of Federal actions. 

exposure. 

Unknown: no acute data 

No after chronic exposure. 

1. Discussion of Risk Quotients 

Yes through effects to terrestrial 

plants (tributarylestuary quality) 

and aquatic plants (food and 

No after acute and/or chronic 

exposure. 

The Agency's LOCs for aquatic vascular plants, non-target terrestrial plants, mammals 

and freshwater invertebrates are exceeded for the use of propazine as outlined in previous 

sections. Should estimated exposure levels occur in proximity to listed resources, the 

available screening level information suggests a potential concern for direct effects on 

listed species within these taxonomic groups listed above associated with the use of 

propazine as described in Section II.A.4. The registrant must provide information on the 

proximity of Federally listed aquatic vascular plants, non-target terrestrial plants, 

habitat) 

Yes through effects to terrestrial 

plants (tributarylestuary quality), 

aquatic plants (food and habitat) 

and other marinelestuarine 
mammals and freshwater invertebrates to the propazine use sites. This requirement may 

be satisfied in one of three ways: I) having membership in the FIFRA Endangered 

Species Task Force (Pesticide Registration [PR] Notice 2000-2); 2) citing FIFRA 

Endangered Species Task Force data; or 3) independently producing these data, provided 

the information is of sufficient quality to meet FIFRA requirements. The information will 

be used by the OPP Endangered Species Protection Program to develop 

recommendations to avoid adverse effects to listed species. 

2. Probit Dose Response Relationship 

A probit dose response analysis was performed for toxicity studies for which slopes with 

95% confidence intervals were available (only marine invertebrates (mysid shrimp)). 

The probit slope response relationship is evaluated to calculate the chance of an 

individual event corresponding to the listed species acute LOCs. The analysis uses the 

EFED spreadsheet IECvl . 1 .xls, developed by Ed Odenkirchen (6122104). It is important 

to note that the IEC model output can go as high as 1 x 10'~ or as low as 1 x 10-16 in 

estimating the event probability. This cut-off is a limit in the Excel spreadsheet 

environment and is not to be interpreted as an agreed upon upper or lower bound 

threshold for concern for individual effects in any given listed species. 

EstuarinelMarine Invertebrates: Based on an assumption of a probit dose response 

relationship with a mean estimated slope of 2.0, the corresponding estimated chance of 

individual mortality associated with the listed species LOC of 0.05 the acute toxic 

endpoint for estuarinelmarine invertebrates is -1 in 2.16 x 1 02. It is recognized that 

extrapolation of very low probability events is associated with considerable uncertainty in 

the resulting estimates. To explore possible bounds to such estimates, the upper and 

lower values for the mean slope estimate (2.94 - 9.1 1) were used to calculate upper and 

lower estimates of the effects probability associated with the listed species LOC. These 

values are -1 in 1.53 x lo4 and >1 in 1 x 1016, respectively. 

3. Data Related to Under-represented Taxa 

Effects data on under-represented taxonomic groups were not submitted by the 

Registrant. In addition, effects data from other analyzed sources (ECOTOX Database, 

PAN Database) were not obtained for this screening risk assessment. 

4. Implications of Sublethal Effects 

Sublethal effects (reduced food consumption and weight loss) were observed in the acute 

avian studies. These effects were observed at levels higher than the estimated terrestrial 

EECs and thus may be observed at the proposed use rates. Chronic studies were 

available for aquatic fish and invertebrates and for mammals. The chronic LOC was 

exceeded for freshwater invertebrates. Chronic exposure of propazine to freshwater 

invertebrates produces adverse effects to growth at 0.091 ppm ai. These growth effects 

may result in adverse effects to the populations of invertebrates thus potentially 

impacting other dependent trophic levels. Chronic RQs exceeded the chronic LOC for 
mammals in all weight classes (1 5 g, 35 g, and 1000g) for consumption of short grasses, 

tall grasses and broadleaf foragelsmall insects at the application rate modeled and 

maximum and mean predicted residue levels; and for 15 and 35 g mammals for 

consumption of fruit and large insects at the application rate and maximum predicted 

residue levels. In a 3-generation reproduction study with rats, propazine produced 

decreased body weights in males and females at doses of 50 mg/kg/day with a NOAEL of 

5 mg/kg/day (MRID 000414-09). The growth-related effects observed in these studies 

may lead to a potential concern for impacts to populations of mammals consuming feed 

items contaminated with propazine and to the predators that feed on them. 

c. Indirect Effects Analysis 

The Acute and Endangered Species LOCs for non-target monocots and dicots were 

exceeded for plants located adjacent to treated areas, in semi-aquatic areas, and by drift 

for the scenarios analyzed. The guideline terrestrial plant studies indicate direct adverse 

effects to seedling emergence and vegetative vigor, as well as non-lethal effects including 

stunting, chlorosis, necrosis and plant death. The LOC for endangered species was 

exceeded for freshwater vascular plants for runoffldrift from ground and aerial spray 

applications to sorghum. In the guideline aquatic vascular plant studies, concentrations 

as low as 0.10 mg/L resulted in inhibition of plant growth and reduction of frond count. 

Damage to non-target plants may be sufficient to prevent the plant fiom competing 

successfully with other plants for resources and water. Endangered plant species may be 

especially impacted by exposure to propazine because of the impact of the loss of a few 

individuals to the population. Consequently, there is a potential concern for listed species 

with either broad or narrow dependencies on impacted plant 

species/populations/communities for habitat, feeding or cover requirements. In terrestrial 

and shallow-water aquatic communities, plants are the primary producers upon which the 

succeeding trophic levels depend. If the available plant material is impacted due to the 

effects of propazine, this may have negative effects not only on the herbivores, but 

throughout the food chain. Also, depending on the severity of impacts to the plant 

communities [i.e., forests, wetlands, ecotones (edge and riparian habitats)], community 

assemblages and ecosystem stability may be altered (i.e. reduced bird populations in edge 

habitats; reduced riparian vegetation resulting in increased light penetration and 

temperature in aquatic habitats, loss of cover and food for fish). 

The chronic LOC for mammals was exceeded in all weight classes for selected food 

categories. Plants dependent upon mammals for pollination and birds, other mammals, 

reptiles and terrestrial amphibians dependent upon small mammals for food may be 

impacted by decreasing mammal populations. Similarly, the chronic LOC for freshwater 

invertebrates was exceeded with the proposed propazine application rates and uses. 

Birds, amphibians, reptiles, mammals, fish and other aquatic invertebrates may be 

impacted by decreasing freshwater invertebrate populations. 
d. Critical Habitat 

In the evaluation of pesticide effects on designated critical habitat, consideration is given 

to the physical and biological features (constituent elements) of a critical habitat 

identified by the U.S Fish and Wildlife and National Marine Fisheries Services as 

essential to the conservation of a listed species and which may require special 

management considerations or protection. The evaluation of impacts for a screening 

level pesticide risk assessment focuses on the biological features that are constituent 

elements and is accomplished using the screening-level taxonomic analysis (risk 

quotients, RQs) and listed species levels of concern (LOCs) that are used to evaluate 

direct and indirect effects to listed organisms. 

The screening-level risk assessment has identified potential concerns for indirect effects 

on listed species for those organisms dependant upon aquatic vascular and non-vascular 

plants, terrestrial plants and terrestrial plants growing in semi-aquatic areas, mammals 

and freshwater invertebrates. In light of the potential for indirect effects, the next step for 

EPA and the Service(s) is to identify which listed species and critical habitat are 

potentially implicated. Analytically, the identification of such species and critical habitat 

can occur in either of two ways. First, the agencies could determine whether the action 

area overlaps critical habitat or the occupied range of any listed species. If so, EPA 

would examine whether the pesticide's potential impacts on non-endangered species 

would affect the listed species indirectly or directly affect a constituent element of the 

critical habitat. Alternatively, the agencies could determine which listed species depend 

on biological resources, or have constituent elements that fall into, the taxa that may be 

directly or indirectly impacted by the pesticide. Then EPA would determine whether use 

of the pesticide overlaps the critical habitat or the occupied range of those listed species. 

At present, the information reviewed by EPA does not permit use of either analytical 

approach to make a definitive identification of species that are potentially impacted 

indirectly or critical habitats that is potentially impacted directly by the use of the 

pesticide. EPA and the Service(s) are working together to conduct the necessary 

analysis. 

This screening-level risk assessment for critical habitat provides a listing of potential 

biological features that, if they are constituent elements of one or more critical habitats, 

would be of potential concern. These correspond to the taxa identified above as being of 

potential concern for indirect effects and include the following: mammals, freshwater 

invertebrates, aquatic vascular and non-vascular plants, terrestrial plants and terrestrial 

plants growing in semi-aquatic areas. This list should serve as an initial step in problem 

formulation for further assessment of critical habitat impacts outlined above, should 

additional work be necessary. 

e. Co-occurrence Analysis 

Since there are potential direct and/or indirect effects on all taxa, LOCATES was run for 

all taxonomic groups. The LOCs for terrestrial monocots, dicots and aquatic plants as 

well as chronic LOCs for freshwater invertebrates and mammals were exceeded; 
consequently a potential concern arises for species with both narrow (i.e., species that are 

obligates or have very specific habitat or feeding requirements) and general dependencies 

(i.e., cover type requirements). Information from LOCATES, as presented in Table IVB 10 below, indicates that for propazine, a number of potentially affected species of 

plants, mammals and freshwater invertebrates appear to be co-located with pesticide use 

areas. Consequently, there may be a concern for potential indirect effects to listed 

species dependent upon mammals that consume feed items contaminated with propazine 

residues and freshwater invertebrates that live in propazine contaminated water such as 

predatory birds, fish, amphibians, reptiles and mammals. In addition, there may be a 

potential concern for indirect effects related to plants that require mammals for 

pollination or seed dispersal and for animals that require terrestrial andlor aquatic 

vegetation for food, habitat and/or stream quality. 
Table IV-B 11 Unique Taxa Count by State for Sorghum 

Colorado, New Mexico, Kansas, Nebraska, Oklahoma, Texas, South Dakota, Arizona, Califomia, North Carolina, Maryland, Louisiana, 

Mississippi, Arkansas, Tennessee, Kentucky, Missouri, Illinois 

Amphibian Arachnid Bird Bivalve Crustacea Dicot Ferns FishGastropod Insect Lichen Mammal Marine Monocot Reptile 

Counties: 32 8 763 147 27 206 1 294 7 69 5 414 7 7 1 54 

States: 4 2 18 10 8 15 1 18 6 13 1 18 1 13 8 

Species: 11 11 2 8 5 1 13 118 1 5 8 9 20 1 29 I 18 14 
C. Description of Assumptions, Limitations, Uncertainties, Strengths, and Data Gaps 

1. Uncertainties, assumptions, and limitations associated with models 

Aauatic Models 

Extrapolating the risk conclusions from the standard pond scenario modeled by 

PRZM/EXAMS may either underestimate or overestimate the potential risks. Major 

uncertainties with the standard runoff scenario are associated with the physical construct 

of the watershed and representation of vulnerable aquatic environments for different 

geographic regions. The physicochemical properties (pH, redox conditions, etc.) of the 

standard farm pond are based on a Georgia farm pond. These properties are likely to be 

regionally specific because of local hydrogeological conditions. Any alteration in water 

quality parameters may impact the environmental behavior of the pesticide. The farm 

pond represents a well mixed, static water body. Because the farm pond is a static water 

body (no flow through), it does not account for pesticide removal through flow through 

or accidental water releases. However, the lack of water flow in the farm pond provides 

an environmental condition for accumulation of persistent pesticides. The assumption of 

uniform mixing does not account for stratification due to thermoclines (e.g., seasonal 

stratification in deep water bodies). Additionally, the physical construct of the standard 

runoff scenario assumes a watershed:pond area ratio of 10. This ratio is recommended to 

maintain a sustainable pond in the Southeastern United States. The use of higher 

watershed:pond ratios (as recommended for sustainable ponds in drier regions of the 

United States) may lead to higher pesticide concentrations when compared to the 

standard watershed:pond ratio. 

The standard pond scenario assumes that uniform environmental and management 

conditions exist over the standard 10 hectare watershed. Soils can vary substantially 

across even small areas, and thus, this variation is not reflected in the model simulations. 

Additionally, the impact of unique soil characteristics (e.g., fragipan) and soil 

management practices (e.g., tile drainage) are not considered in the standard runoff 

scenario. The assumption of uniform site and management conditions is not expected to 

represent some site-specific conditions. Extrapolating the risk conclusions from the 

standard pond scenario to other aquatic habitats (e.g., marshes, streams, creeks, and 

shallow rivers, intermittent aquatic areas) may either underestimate or overestimate the 

potential risks in those habitats. 

There are limited monitoring studies for propazine in freshwater environments and no 

studies in marine environments; therefore, the exposure of aquatic species to propazine is 

based entirely on the modeled data. The output of models such as PRZMIEXAMS is 

dependent upon the quality of the environmental fate input parameters. No aquatic 

dissipation studies are available, and an assumption regarding the half-life of propazine in 

aqueous bodies such as lakes, ponds, etc. had to be made from laboratory data on the 

aerobic soil degradation half-life. Future monitoring studies and aquatic dissipation field 

studies would be useful in order to determine how well the modeled results fit measured 

levels of propazine in aquatic environments following its application to sorghum at 

appropriate rates. 
Terrestrial Models 

The data available to support the terrestrial exposure assessment for propazine are 

substantially complete, with the exception of a foliar dissipation study, which is an input 

variable for modeling of risks to birds and mammals (i.e.,T-REX). The terrestrial 

modeling was conducted using a default foliar half-life value of 35 days. Use of this 

default value could overestimate the foliar half-life for propazine, higher terrestrial EECs, 

and risk. However, it should be noted that because the EEC represents the concentration 

immediately following a direct application, the foliar half-life variable is only influential 

for scenarios involving multiple applications. 

As discussed earlier in the exposure section of this document, the Agency relies on 

the work of Fletcher et al. (1 994) for setting the assumed pesticide residues in wildlife 

dietary items. The Agency believes that these residue assumptions reflect a realistic 

upper-bound residue estimate, although the degree to which this assumption reflects a 

specific percentile estimate is difficult to quantify. It is important to note that the 

field measurement efforts used to develop the Fletcher estimates of exposure involve 

highly varied sampling techniques. It is entirely possible that much of these data 

reflect residues averaged over entire above ground plants in the case of grass and 

forage sampling. Depending upon a specific wildlife species' foraging habits, whole 

aboveground plant samples may either underestimate or overestimate actual exposure. 

The acute and chronic characterizations of risk rely on comparisons of wildlife 

dietary residues with LC5() or NOAEC values expressed in concentrations of 

pesticides in laboratory feed. These comparisons assume that ingestion of food items 

in the field occurs at rates commensurate with those in the laboratory. Although the 

screening assessment process adjusts dry-weight estimates of food intake to reflect 

the increased mass in fresh-weight wildlife food intake estimates, it does not allow for 

gross energy and assimilative efficiency differences between wildlife food items and 

laboratory feed. On gross energy content alone, direct comparison of a laboratory 

dietary concentration-based effects threshold to a fresh-weight pesticide residue 

estimate would result in an underestimation of field exposure by food consumption by 

a factor of 1.25 - 2.5 for most food items. Only for seeds would the direct 

comparison of dietary threshold to residue estimate lead to an overestimate of 

exposure. Differences in assimilative efficiency between laboratory and wild diets 

suggest that current screening assessment methods do not account for a potentially 

important aspect of food requirements. Depending upon species and dietary matrix, 

bird assimilation of wild diet energy ranges from 23 - 80%, and mammal's 

assimilation ranges fkom 41 - 85% (U.S. Environmental Protection Agency, 1993). If 

it is assumed that laboratory chow is formulated to maximize assimilative efficiency 

(e.g., a value of 85%), a potential for underestimation of exposure may exist by 

assuming that consumption of food in the wild is comparable with consumption 

during laboratory testing. In the screening process, exposure may be underestimated 

because metabolic rates are not related to food consumption. 
For the terrestrial organism risk assessment, the EECs on food items generated using 

T-REX may be compared directly with dietary toxicity data or converted to an oral 

dose to calculate chronic dose-based RQs, as is the case for small mammals. The 

screening-level risk assessment for propazine uses upper bound predicted residues as 

the measure of exposure. For mammals, the residue concentration is converted to 

daily oral dose based on the fraction of body weight consumed daily as estimated 

through mammalian allometric relationships. Converting to the oral dose-based 

chronic RQs from the reported mammalian dietary chronic endpoint allows EFED to 

evaluate the risk to different size-classes of mammals with varying feeding habits. 

However, this extrapolation method for generating dose-based chronic RQs for 

smaller animals based on dietary-based data for larger animals, may also increase 

uncertainty in this risk assessment. 

Finally, the screening procedure does not account for situations where the feeding 

rate may be above or below requirements to meet free living metabolic requirements. 

Gorging behavior is a possibility under some specific wildlife scenarios (e.g., bird 

migration) where the food intake rate may be greatly increased. Kirkwood (1 983) has 

suggested that an upper-bound limit to this behavior might be the typical intake rate 

multiplied by a factor of 5. In contrast is the potential for avoidance, operationally 

defined as animals responding to the presence of noxious chemicals in their food by 

reducing consumption of treated dietary elements. This response is seen in nature 

where herbivores avoid plant secondary compounds. 

2. Uncertainties, assumptions, and limitation associated with exposure scenarios 

Screening-level risk assessments for spray applications of pesticides consider dietary 

exposure alone. Other potential routes of exposure to propazine for terrestrial organisms 

are discussed below. 

Incidental soil ingestion exposure 

This risk assessment does not consider incidental soil ingestion. Available data suggests 

that up to 15% of the diet can consist of incidentally ingested soil depending on the 

species and feeding strategy (Beyer et al., 1994). A simple first approximation of soil 

concentration of pesticide from spray application shows that ingestion of soil at an 

incidental rate of up to 15% of the diet would not increase dietary exposure. 

Inhalation exposure 

The screening risk assessment does not consider inhalation exposure. Such exposure 

may occur through three potential sources: (1) spray material in droplet form at the time 

of application (2) vapor phase pesticide volatilizing from treated surfaces, and (3) 

airborne particulate (soil, vegetative material, and pesticide dusts). 

Available data suggest that inhalation exposure at the time of application is not an 

appreciable route of exposure for birds. According to research on mallards and bobwhite 

quail, respirable particle size in birds (particles reaching the lung) is limited to a 

maximum diameter of 2 to 5 microns. The spray droplet spectra covering the majority of 
pesticide application situations (AgDRIFT model scenarios for very-fine to coarse droplet 

applications) suggests that less than 1 % of the applied material is within the respirable 

particle size. 

Theoretically, inhalation of pesticide's active ingredient in the vapor phase may be 

another source of exposure for some pesticides under some exposure situations. 

However, volatilization of propazine from water and soil surfaces is not expected; 

therefore, inhalation should not be an important exposure pathway. 

The impact from exposure to dusts contaminated with the pesticide cannot be assessed 

generically because soil properties (chemical and physical), which impact the estimation 

of such exposures are highly site-specific. 

Dermal Exposure 

The screening assessment does not consider dermal exposure, except as it is indirectly 

included in calculations of RQs based on lethal doses per unit of pesticide treated area. 

Dermal exposure may occur through three potential sources: (1) direct application of 

spray to terrestrial wildlife in the treated area or within the drift footprint, (2) incidental 

contact with contaminated vegetation, or (3) contact with contaminated water or soil. 

Data which address dermal exposure of wildlife to pesticides in a quantitative fashion are 

extremely limited. The Agency is actively pursuing modeling techniques to account for 

dermal exposure via direct application of spray and by incidental contact with vegetation. 

Drinking Water Exposure 

The exposure of a target organism to a pesticide's active ingredient may be the result of 

consumption of surface water, groundwater or consumption of the pesticide in dew or 

other water on the surfaces of treated vegetation or in puddled water on treated fields. 

For the active ingredients of a pesticide there is a potential to dissolve in runoff and 

puddles on the treated field may contain the chemical. However, propazine exhibits 

limited solubility; consequently, the potential for drinking water exposure should be 

reduced. 

3. Uncertainties, assumptions, and limitation associated with the toxicity data 

Species Selection and Sensitivity 

There are a number of areas of uncertainty in the terrestrial and the aquatic organism risk 

assessments that could potentially cause an underestimation of risk. Use of toxicity data 

on representative species does not provide information on the potential variability in 

susceptibility to acute and chronic exposures. For screening terrestrial risk assessments, a 

generic bird or mammal is assumed to occupy either the treated field or adjacent areas 

receiving the pesticide at a rate commensurate with the treatment rate on the field. The 

actual habitat requirements of any particular terrestrial species are not considered, and it 

is assumed that species occupy, exclusively and permanently, the treated area being 

modeled. This assumption leads to a maximum level of exposure in the risk assessment. 
Although the screening risk assessment relies on a selected toxicity endpoint from the 

most sensitive species tested, it does not necessarily mean that the selected toxicity 

endpoints reflect sensitivity of the most sensitive species existing in a given environment. 

The relative position of the most sensitive species tested in the distribution of all possible 

species is a function of the overall variability among species to a particular chemical. In 

the case of listed species, there is uncertainty regarding the relationship of the listed 

species' sensitivity and the most sensitive species tested. 

Surrogates were used to predict potential risks for species with no data (i.e., reptiles and 

amphibians). It was assumed that the use of surrogate effects data is sufficiently 

conservative to apply to the broad range of species within taxonomic groups. If other 

species are more or less sensitive to propazine than the surrogates, risks may be under- or 

overestimated, respectively. 

Aae class and sensitivity of effects thresholds 

Scientists generally recognize that the age of the test organism may have a significant 

effect on the observed sensitivity to a toxicant. In a screening-level assessment of acute 

toxicity in fish, data are collected on juveniles weighing 0.1 to 5 grams. For aquatic 

invertebrates, the recommended acute testing is performed on immature age classes (e.g., 

first instar for daphnids, second instar for amphipods, stoneflies and mayflies, and third 

instar for midges). Similarly, acute dietary testing with birds is also performed on 

juveniles, with mallard ducks tested at 5-10 days of age and quail at 10-14 days of age. 

Testing of juveniles may overestimate the toxicity of direct acting pesticides in adults. As 

juvenile organisms do not have fully developed metabolic systems, they may not possess 

the ability to transform and detoxify xenobiotics equivalent to the olderladult organism. 

The screening risk assessment has no current provisions for a generally applied method 

that accounts for this uncertainty. In so far as the available toxicity data may provide 

ranges of sensitivity information with respect to age class, the risk assessment uses the 

most sensitive life-stage information as the conservative screening endpoint. 

4. Uncertainties and assumptions associated with gaps in environmental fate and 

toxicity data 

The following data gaps and uncertainties were identified with respect to the submitted 

ecotoxicity effects data: 

$ Acute risks for freshwater fish were not characterized because the submitted study 

was determined to be invalid based on solubility issues. The acute freshwater 

invertebrate study was also determined to be supplemental. A high degree of 

uncertainty exists for the freshwater toxicity data for propazine until it can be 

shown that the results reflect that the tests were conducted up to the limit of 

solubility. An acceptable study will improve the certainty of the risk assessment. 

$ Chronic risk to avian species was not characterized because no studies with the 

TGAI were submitted. 
$ Current data are not available to assess potential risk of propazine degradates to 

aquatic fish and invertebrates and terrestrial plants. 

$ Dermal contact and soil ingestion pathways for terrestrial mammals and birds 

were not evaluated because these routes of exposure are not considered in 

deterministic risk assessments. Data which address dermal exposure of wildlife to 

pesticides in a quantitative fashion are extremely limited. The Agency is actively 

pursuing modeling techniques to account for dermal exposure via direct 

application and by incidental contact. 

$ Risks to semiaquatic wildlife via consumption of pesticide-contaminated fish 

were not evaluated. However, given that bioaccumulation of propazine is 

expected to be low, ingestion of fish by piscivorus wildlife is not likely to be of 

concern. 

$ Risks to top-level carnivores were not evaluated due to a lack of data for these 

receptors. Ingestion of grass, plants, hits, insects, and seeds by terrestrial 

wildlife was considered; however, consumption of small mammals and birds by 

carnivores was not evaluated. In addition, food chain exposures for aquatic 

receptors (i.e., fish consumption of aquatic invertebrates and/or aquatic plants) 

were also not considered. However, propazine's low &, suggests that it is not 

likely to bioaccumulate. 

$ Fate studies indicate propazine is persistent and mobile raising concerns about the 

impact on groundwater and surface water. The field dissipation studies that have 

been submitted are considered unacceptable or supplemental resulting in a 

significant uncertainty for this transport pathway. To address this uncertainty 

studies are needed to comprehensively ascertain the mobility of propazine and its 

degradates under field conditions. 

$ No aerobic aquatic metabolism data is available for use in this assessment. An 

assumption was made that the aerobic aquatic metabolism half life is twice the 

aerobic soil metabolism half life. This represents an uncertainty in the assessment 

and additional data on the specific behavior of propazine in aerobic aquatic 

systems would be needed to eliminate this uncertainty. 
V. Literature Cited 

Brown, C.B., and J.L. White. 1969. Reactions of 1,2-s-triazines with soil clays. Soil Sci. Soc. 

Am. Proc. 33:863-867. 

Burkhard, N., and J.A. Guth. 198 1. Chemical hydrolysis of 2-chloro-4,6-bis(alky1-amino)- 

1,3,5-triazine herbicides and their breakdown under the influence of adsorption. Pestic. 

Sci. 12:45-52. 

Harris, C.I. 1966. Adsorption, movement, and phytotoxicity of monuron and s-triazine 

herbicides in soils. Weeds 14:6-10. 

Hayes, M.H.B. 1970. Adsorption of triazine herbicides on soil organic matter, including a short 

review of soil organic matter chemistry. Residue Rev. 3 1 : 13 1-1 74. 

Khan, Shahamat U. 1980. Pesticides in the soil environment. Elsevier Scientific Publishing 

Company, Amsterdam. p. 90-97. 

Koskinen, W.C., and S.S. Harper. 1990. The retention process: mechanisms. p. 51-77 In H.H. 

Cheng (ed.) Pesticides in the soil environment: processes, impacts, and modeling. SSSA 

Book Series No. 2. Soil Science Society of America, Madison, WI. 

Montgomery, J.H. 1993. Agrochemicals desk reference: environmental data. Lewis Publishers, 

Chelsea, MI. p. 356-358. 

Nearpass, D.C. 1972. Hydrolysis of propazine by the surface acidity of organic matter. Soil 

Sci. Soc. Am. Proc. 36:606-610. 

Russell, J.D., M. Curz, and J.L. White. 1968. Mode of chemical degradation of s-triazines by 

montmorillonite. Science 160: 1340- 1342. 

Talbert, R.E., and O.H. Fletchall. 1965. The adsorption of some s-triazines in soils. Weeds 

13:46-52. 

Walker, A., and D.V. Crawford. 1970. Diffusion coefficients for two triazine herbicides in six 

soils. Weed Res. 10: 126-132. 

Wolfe, N.L., U. Mingelgrin, and G.C. Miller. 1990. Abiotic transformations in water, 

sediments, and soil. p. 103-1 68 In H.H. Cheng (ed.) Pesticides in the soil environment: 

processes, impacts, and modeling. SSSA Book Series No. 2. Soil Science Society of 

America, Madison, WI. 

Worthing, C.R., ed. 1983. The pesticide manual: A world compendium. Croydon, England: The 

British Crop Protection Council. 
Appendix A. Propazine 4L Label 
Appendix B. Environmental Fate Studies 
Hydrolysis (161-1, MRID 436898-02, Study Status: Acceptable). 

Ring-labeled ['4~]-propazine [6-chloro-N,N'-bis(1 -methylethyl)- l,3,5-triazine-2,4-diamine; 

radiochemical purity 98.4%, specific activity 104.4 pCiImg] was added to aqueous buffered 

solutions of pH 5 (0.1 M acetate), pH 7 (0.1 M phosphate), or pH 9 (0.01 M borate) at a 

concentration of 5 ppm. The [14~]-propazine stock solutions were prepared in toluene and added 

to autoclaved buffered solutions. Acetonitrile was added as a co-solvent at a concentration of 

1 %. Aliquots of the solutions were radioassayed to confirm that the ['4~]-propazine was 

completely in solution. The sample flasks were incubated in the dark at 25 + O°C. Triplicate 

samples were removed for analysis after 0, l,3,7, 14,21, and 30 days of incubation. Aliquots of 

the 0- and 30-day samples were tested for sterility using trypticase soy and potato dextrose agar 

plates. 

Total recovered radioactivity ranged from 97.8 - 107.5% (mean 100.7 + 2.5%) for the pH 5 

samples; 98.4 - 106.6% (mean 102.2 2 2.5%) for the pH 7 samples; and 96.9 - 106.4% (mean 

102.3 t 2.7%) for the pH 9 samples. Propazine showed no evidence of decline in the pH 5,7, or 

9 buffer solutions (Tables V-VII). At the end of the 30-day incubation period, recovered 

propazine levels comprised approximately 103% of the initial radioactivity in all buffer 

solutions, with no degradates in excess of 1.5% of the applied. The plot of propazine 

concentration with time showed no evidence of decline over the study. The slope was not 

significantly >O. While volatiles were not trapped, the material balances suggest that volatile 

losses were not significant. Results of the study indicate that hydrolysis is not a major avenue of 

environmental degadation for propazine. 

Photodegradation in Water (161-2, MRIDs 001537-09,441848-05) 

MRID 441 848-05 (Study Status: Acceptable) 

DER not available at date ofpublication 

MRID 001 537-09 (Study Status: Supplemental) 

Propazine was photolytically stable in aqueous solutions (2.5 ppm propazine; further 

characterization not provided) when exposed to natural sunlight for up to 17 days, less than the 

one-month time period specified for photolysis studies. In a second part of the study, propazine 

degraded under artificial light (source not specified) with a half life of 24 hr. However, greater 

than 50% of the applied radioactivity was not accounted for in the material balance. These 

studies were considered supplemental and do not completely satisfy the environmental fate 

requirements for the aqueous photolysis of propazine. 

Photodegradation on Soil (161-3, MRIDs 441848-06, Study Status: Acceptable) 

DER not available at date ofpublication 

Photodegradation in Air (161-4) 

No Study 

Aerobic Soil Metabolism (162-1, MRIDs 441848-07 and 001537-12, 
MRID 44 1 848-07 

DER not available at date ofpublication (Study Status: Acceptable) 

MRID 001 537- 12 (Study Status: Acceptable) 

Propazine, applied to a nonsterile loamy sand soil (9% clay, 86% sand; 2.2% organic C; pH 5.6) 

at a rate of 10 ppm, degraded with a half-life of 12 to 24 weeks (calculated half-life was 15 

weeks) under dark incubation at 25OC. The major degradate, hydroxy-propazine [2-hydroxy-4,6- 

bis(isopropy1amino)-s-triazine], comprised 14% of the applied radioactivity after 12 weeks and 

3 1% after 52 weeks. Unextractable residues accounted for an additional 35% at 12 weeks and 

58% after 52 weeks. 

In sterilized loamy sand soil (method of sterilization was not indicated), propazine degraded with 

a half-life of 8 to 12 weeks. Hydroxy-propazine comprised 16% of the applied radioactivity after 

12 weeks while unextracted residues accounted for 3 1 %. 

The shorter half-life in the sterile soil may have resulted from alterations in soil properties due to 

sterilization or may indicate that factors other than microorganisms, such as surface catalysis, 

may play a role in the degradation of propazine. 

Anaerobic Soil Metabolism (162-2, MRIDs 001537-13, Study Status: Acceptable) 

In an acceptable study propazine degraded with a half-life of 8 weeks in a nonsterile loamy sand 

soil which was incubated anaerobically after 4 weeks of aerobic incubation. Propazine declined 

fi-om 77% to 36% of the applied after 8 weeks while the major degradate, hydroxy-propazine 

increased to 12%. Unextracted residues comprised 50% of the applied after 8 weeks of 

anaerobic incubation. 

Anaerobic Aquatic Metabolism (162-3) 

No Study 

Aerobic Aquatic Metabolism (162-4) 

No Study 

Leaching - Adsorption/Desorption (163-1, MRIDs 001529-97,436898-03,496898-04, 

442873-13) 

MRID 001 529-97 (Study Status: Acceptable) 

DER not available at date ofpublication 

In that study, propazine was highly mobile, with Freundlich I& values for adsorption/desorption 

of 0.3416.09 for loamy sand, 1.1413.78 for sandy loam, 2.69116.8 for loam, and 3.19/44.7 for clay 

loam. The adsorption &, values were 65 for clay loam, 83 for loamy sand, 123 for sandy loam, 

and 158 for loam. 

MRID 436898-03 (Study Status: Acceptable) 

The mobility of propazine andlor its degradates, applied at a rate of 5 ppm to four soils and aged 

for 30 days, varied with soil type and, possibly, column packing. An average of 2% (sandy 
loam) to 19% (sand) of the applied radioactivity was collected in the leachate. While the 

majority of the applied radioactivity remained in the 0-6 cm soil sections, ranging from 52% 

(loam) to 84% (sandy loam), radioactive residues were detected in each of the column sections, 

indicating a redistribution of the aged propazine residues during the leaching process. Propazine 

was the only 14c-residue identified in the leachate fractions and was the dominant residue in the 

0-6 cm column sections. 

A supplemental study (MRID 001537-14) reviewed for the 1987 EAB Science Chapter also 

found that the aged propazine residues were mobile (33% leached in sand soil) to slightly mobile 

(4% leached in loam soil). 

A second adsorptioddesorption study (MRID 001 529-97) that was found acceptable in the 1987 

EAB document also found that propazine was highly mobile. The Freundlich IQ values for 

adsorptionldesorption were 0.3416.09 for loamy sand, 1.1413.78 for sandy loam, 2.6911 6.8 for 

loam, and 3.19144.7 for clay loam. The adsorption LC values were 65 for clay loam, 83 for 

loamy sand, 123 for sandy loam, and 158 for loam. 

In addition, that study found that the major degradate, hydroxy-propazine [2-hydroxy-4,6- 

bis(isopropy1amino)-s-triazine], was less mobile than propazine. The Freundlich Kd values for 

adsorptionldesorption of I. 1313.42 for loamy sand, 2.9415.53 for sandy loam, 3 1.8156.8 for loam, 

and 106/143 for clay loam. The adsorption LC values were 276 for loamy sand, 359 for sandy 

loam, 187 1 for loam, and 2 163 for clay loam. 

MRID 496898-04 (Study Status: Acceptable) 

Sand, sandy loam, loam, and silty clay soil samples were collected from the surface horizons of 

soils in Fayette and Madison Counties, ICY. A 24-hour equilibration period was selected for the 

definitive study. The material balance for the individual replications in the definitive study 

ranged from 89.5 to 100.7%. The percentage of applied radioactivity adsorbed on the soils 

decreased with increasing concentration of propazine in the aqueous solution, from 39.0% to 

3 1.4% for the sandy loam sample, 4 1 .O% to 34.8% for the sand, 39.4% to 32.6% for the loam, 

and 43.3% to 32.0% for the silty clay. Similarly, the percentage of the adsorbed radioactivity 

that was desorbed also decreased with increasing initial propazine concentration, from 32.6% to 

26.9% for the sandy loam sample, 19.9% to 12.0% for the sand, 37.6% to 35.0% for the loam, 

and 35.8% to 26.8% for the silty clay. 

The Freundlich Kd values for adsorptionldesorption of propazine were calculated to be 0.67186.4 

for sand, 1.2811 1.9 for sandy loam, 1.30127.0 for silty clay, and 1.3516.7 for loam. The 

adsorption LC values, calculated by the equation (Kd /%organic C) x 100, were 78.7 for the 

loam, 96.0 for the silty clay, 127.6 for the sandy loam, and 268.4 for the sand. The calculated Kd 

and LC values indicate that propazine is highly to moderately mobile in soils. 

The major degradate, hydroxy-propazine [2-hydroxy-4,6-bis(isopropylamino)-s-trine], is less 

mobile than propazine, with Freundlich I& values for adsorptioddesorption of 1.1313.42 for 

loamy sand, 2.9415.53 for sandy loam, 31.8156.8 for loam, and 1061143 for clay loam. The 

adsorption I?, values were 276 for loamy sand, 359 for sandy loam, 1871 for loam, and 21 63 for 

clay loam. 
MRID 442873- 1 3 (Study Status: Acceptable) 

Sandy loam was collected in Fayette County, while sand, loam, and silty clay soil samples were 

collected in Madison County, Kentucky. The overall material balance of the applied 

radioactivity was 98.4*0.7% (mean * % standard deviation). The material balance for the 

individual doses in the definitive study ranged from 92.7 to 104.3%. As the concentration of 2- 

hydroxy-propazine in the aqueous solution increased, the percentage of applied radioactivity 

absorbed on each soil sample decreased during the adsorption phase: 41.69 to 34.75% for sandy 

loam, 44.83 to 36.60% for sand, 58.59 to 51.42% for loam, and 75.92 to 67.26% for silty clay. 

However, the trend of decreasing absorbed radioactivity with increasing solution concentration 

was not observed during the desorption phase. Instead, the desorbed radioactivity generally 

increased with increasing solution concentration in 3 soils: 18.70 to 22.19% for sand, 16.26 to 

22.19% for loam, and 12.00 to 14.52% fro silty clay. No specific trend could be deciphered for 

sandy loam. 

The adsorption Kd values of 2-hydroxy-propazine were calculated to be 1.447 for sandy loam, 

0.823 for sand, 1.334 for loam and 4.659 for silty clay. The desorption coefficients were 6.610 

fro sandy loam, 4.167 for sand, 3.123 for loam, and 12.362 fro silty clay. The adsorption and 

desorption coefficients were then normalized to organic carbon content by multiplying &by 

(100% organic C) to yield KO,. The adsorption I&,, values were 144.7 for sandy loam, 329.2 fro 

sand, 78.0 for loam and 342.6 for silty clay. 

Laboratory Volatilization (163-2) 

No Study 

Field Dissipation (164-1, MRIDs 442873-14,441848-09) 

MIRD 442873- 14 (Study Status: Supplemental) 

After application, propazine dissipated rapidly with two reported half-live: 7.2 days for a period 

of 1 to 21 days and 58.2 days for a period of 28 to 184 days. Residues of propazine were found 

in the 0-3,3-6, and 6-9 inch depths during the first 14 days. After 21,28, and 90 days, propazine 

was detected in the 0-3 and 3-6 inch depths. After 90 days, residues of propazine were found 

only in the 0-3 in depth. The three degradates of propazine that were detected in the soil samples 

included 2-amino-4-chloro-6-isopropylamino-s-train (DEA); 2,4-diamino-6-chloro-s-triazine 

(DAA); and 4,6-diissopropylamino-2-hydroxy-s-triazine or 2-hydroxyprpazine (OH-propazine). 

MRID 44 1848-09 (Study Status: Supplemental) 

The four submitted studies were either unacceptable or considered supplemental because of 

inadequate sampling depths (only the upper 12 inches were sampled), lack of freezer stability 

data (some samples were frozen for up to 3 years), and/or the presence of propazine in the 

control and treated plots prior to the start of the study. Supplemental data suggest that propazine, 

applied as a wettable powder at 2.4 to 4.8 lb a.i./A/yr, dissipated from the upper 6 inches with a 

half-life of <30 to 149 days in NY, <3 1 days in CA, and 60 to >357 days in NE. The degradates 

hydroxy-propazine, G-2873 [2-chloro-4,6-diamino-s-triazine], and G-30033 [2-chloro-4-amino6-isopropylamino-s-triazine] were detected in one or more of the field studies (NY, CA, NE). 

Aquatic Field Dissipation (164-2) 
No Study 

Small Scale Prospective Groundwater Monitoring (166-1) 

No Study 
Names and Chemical Structures of Propazine and Major Transformation Products 

Propazine (Propazine 4L) 

IUPAC Name: 6-chloro-~',Af-di-iso~ro~~l-l,3,5 triazine-2,4-diamine 

CAS Name: 6-chloro-N,N1-bis(1 -methylethyl)- l,3,5-triazine-2,4-diamine 

CAS NO: 139-40-2 

Propazine des-ethyl (G-30033) 

lUPAC name: NA 

CAS name: 2-amino-4-chloro-6-(1 -methylethylamino)-s-triazine 

CAS No: NA 

DACT (G-28273) 

IUPAC name: NA 

CAS name: 2,4-diamino-6-chloro-s-triazine 

CAS No: NA 
Propazine 2-hydroxy or 2-hydroxypropazine (G-S 1 1526) 

IUPAC name: NA 

CAS name: 2-hydroxy-4,6-bis-(l-methylethylamino)-s-triazine 

CAS No: NA 

Desisopropyl hydroxypropazine 

IUPAC name: NA 

CAS name: 4-amino-2-hydroxy-6-isopropylaminotriazine 

CAS No: NA 

Ammeline (GS- 1 779 1) 

IUPAC name: NA 

CAS name: 2,4-diamino-6-hydroxy-s-triazine 

CAS No: NA 
Triazine-methyl-triamine (CGA- 101 248) 

IUPAC name: NA 

CAS name: N-(1 -methyl)-1,3,5-triazine-2,4,6-triamine 

CAS No: NA 

Prometon (G-3 143 5) 

IUPAC name: NA 

CAS name: 2-methoxy-4,6-bis (1 -methylethylamino)-s-triazine 

CAS No: NA 

Propazine-2-methyl-sulfinyl (GS-16141) 

IUPAC name: NA 

CAS name: 2,4-bis (1 -methylethylamino)-6-methylsulfinyl-s-triazine 

CAS No: NA 
Appendix C. Aquatic Exposure Model and Results (PRZMJEXAMS) 
Kansas Sorghum Crop Scenario 

Aerial Spray Application of Propazine 4L 

stored as kssorpropaerial2.out 

Chemical: Propazine 

PRZM environment: KSsorghumC.txt modified Satday, 12 October 2002 at 

15 : 57 : 00 

EXAMS environment: pond298.exv modified Thuday, 24 July 2003 at 10:02:00 

Metfile: w13996.dvf modified Wedday, 3 July 2002 at 09:04:44 

Water segment concentrations (ppb) 

Year 

1961 

1962 

1963 

1964 

1965 

1966 

1967 

19 6 8 

1969 

1970 

19 7 1 

1972 

1973 

1974 

1975 

1976 

1977 

1978 

1979 

1980 

1981 

1982 

1983 

1984 

1985 

1986 

1987 

1988 

1989 

1990 

Peak 96 hr 21 Day 60 Day 90 Day Yearly 

9.051 9.009 8.844 8.727 8.589 5.038 

22.23 22.12 21.91 21.29 20.77 14.43 

22.47 22.41 22.25 21.79 21.39 18.65 

24.63 24.56 24.31 23.69 23.23 19.99 

27.32 27.26 27.01 26.47 25.96 22.38 

29.18 29.13 28.79 27.98 27.4 24.04 

34.22 34.12 33.73 33.06 32.44 27.52 

32.13 32.04 31.79 31.23 30.83 28.39 

34.3 34.21 34 33.22 32.55 28.88 

37.24 37.16 36.92 36.35 35.71 30.96 

47.89 47.76 47.23 46.42 45.55 37.28 

39.22 39.12 38.71 38.66 38.51 36.41 

42.67 42.58 42.06 41.13 40.47 35.83 

41.02 40.92 40.5 40.15 39.49 35.55 

37.35 37.28 37.17 36.54 35.95 33.08 

36.22 36.13 35.77 35.01 34.47 31.12 

45.24 45.08 44.76 44.07 43.18 35.54 

49.66 49.49 49 48.3 47.37 40.48 

41.99 41.9 41.52 41.13 40.84 38.55 

44.19 44.06 43.49 42.34 41.4 36.65 

48.64 48.5 47.98 46.92 45.95 39.23 

52.96 52.89 52.54 51.41 50.42 43.31 

48.18 48.1 47.84 46.96 46.08 41.81 

49.54 49.41 48.91 48.09 47.18 41.18 

46.55 46.43 45.98 45.19 44.6 40.65 

51.83 51.69 51.13 49.91 49 42 -28 

47.42 47.28 46.86 46.28 45.45 41.41 

46.01 45.87 45.38 44.3 44.1 40.12 

42.15 42.06 41.67 41.33 40.85 37.89 

50.26 50.12 49.56 48.43 47.47 40.3 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 52.96 52.89 52.54 51.41 50.42 43.31 

0.0645161290322581 51.83 51.69 51.13 49.91 49 42.28 

0.0967741935483871 50.26 50.12 49.56 48.43 47.47 41.81 

0.129032258064516 49.66 49.49 49 48.3 47.37 41.41 

0.161290322580645 49.54 49.41 48.91 48.09 47.18 41.18 

0.193548387096774 48.64 48.5 47.98 46.96 46.08 40.65 

0.225806451612903 48.18 48.1 47.84 46.92 45.95 40.48 

0.258064516129032 47.89 47.76 47.23 46.42 45.55 40.3 

0.290322580645161 47.42 47.28 46.86 46.28 45.45 40.12 

0.32258064516129 46.55 46.43 45.98 45.19 44.6 39.23 

0.354838709677419 46.01 45.87 45.38 44.3 44.1 38.55 

0.387096774193548 45.24 45.08 44.76 44.07 43.18 37.89 
0.1 50.2 50.057 49.504 48.417 47.46 41.77 

Average of yearly averages: 32.9649333333333 

Inputs generated by pe4.pl - 8-August-2003 

Data used for this run: 

Output File: kssorpropaerial2 

Metfile: w13996.dvf 

PRZM scenario: KSsorghumC.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Propazine 

Description Variable Name Value Units Comments 

Molecular weight mwt 230 g/mol 

Henry's Law Const. henry 1.02e-9 atm-mA3/mol 

Vapor Pressure vapr 2.9e-8 torr 

Solubility sol 8.6 mg/L 

K d Kd mg/L 

Koc Koc 125 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 960 days Halfife 

Anaerobic Aquatic Metabolism kbacs 112 days Halfife 

Aerobic Soil Metabolism asm 480 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method : CAM 2 integer See PRZM manual 

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 1.344 kg/ha 

Application Efficiency: APPEFF .95 fraction 

Spray Drift DRFT .05 fraction of application rate applied to pond 

Application Date Date 10-5 dd/mrn or dd/rnrnrn or dd-mm or dd-mmm 

Record 17: FILTRA 

I PSCND 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of 

entire run) 
Kansas Sorghum Crop Scenario 

Ground Spray Application of Propazine 4L 

stored as kssorpropground.out 

Chemical: Propazine 

PRZM environment: KSsorghumC.txt modified Satday, 12 October 2002 at 

15:57:00 

EXAMS environment: pond298.exv modified Thuday, 24 July 2003 at 10:02:00 

Metfile: w13996.dvf modified Wedday, 3 July 2002 at 09:04:44 

Water segment concentrations (ppb) 

Year 

1961 

1962 

1963 

1964 

1965 

1966 

1967 

1968 

1969 

1970 

1971 

1972 

1973 

1974 

1975 

1976 

1977 

1978 

1979 

1980 

1981 

1982 

1983 

1984 

1985 

1986 

1987 

1988 

1989 

1990 

Peak 96 hr 21 Day 60 Day 90 Day Yearly 

6.834 6.801 6.673 6.533 6.46 3.758 

18.62 18.53 18.34 17.83 17.4 11.75 

17.33 17.29 17.18 16.88 16.6 14.84 

18.9 18.84 18.65 18.14 17.77 15.3 

20.79 20.75 20.58 20.12 19.75 17 

22.17 22.13 21.87 21.21 20.78 18.12 

26.92 26.84 26.52 25.93 25.45 21.23 

24.29 24.23 24.01 23.55 23.24 21.69 

26.26 26.2 26.02 25.43 24.92 21.9 

28.93 28.87 28.64 28.15 27.68 23.9 

39.79 39.67 39.21 38.5 37.78 30.38 

31.08 31.05 30.94 30.71 30.52 29.39 

34.28 34.21 33.78 33.02 32.49 28.65 

32.41 32.33 32.01 31.77 31.28 28.33 

28.72 28.67 28.52 28.05 27.57 25.71 

27.34 27.28 27.01 26.43 26.01 23.66 

36.84 36.71 36.38 35.9 35.19 28.29 

41.59 41.5 40.96 40.48 39.71 33.47 

33.66 33.63 33.51 33.26 33.07 31.4 

35.68 35.58 35.11 34.13 33.4 29.47 

40.39 40.27 39.83 38.99 38.19 32.27 

44.76 44.69 44.42 43.47 42.64 36.42 

39.71 39.64 39.38 38.73 38.01 34.8 

41.32 41.21 40.79 40.2 39.46 34.2 

38.31 38.21 37.84 37 36.59 33.61 

43.51 43.39 42.91 41.87 41.11 35.3 

39.34 39.23 38.91 38.37 37.7 34.44 

38.14 38.03 37.62 36.58 36.22 33.13 

33.71 33.63 33.37 33.1 32.8 30.79 

41.82 41.7 41.22 40.31 39.52 33.2 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 44.76 44.69 44.42 43.47 42.64 36.42 

0.0645161290322581 43.51 43.39 42.91 41.87 41.11 35.3 

0.0967741935483871 41.82 41.7 41.22 40.48 39.71 34.8 

0.129032258064516 41.59 41.5 40.96 40.31 39.52 34.44 

0.161290322580645 41.32 41.21 40.79 40.2 39.46 34.2 

0.193548387096774 40.39 40.27 39.83 38.99 38.19 33.61 

0.225806451612903 39.79 39.67 39.38 38.73 38.01 33.47 

0.258064516129032 39.71 39.64 39.21 38.5 37.78 33.2 

0.290322580645161 39.34 39.23 38.91 38.37 37.7 33.13 

0.32258064516129 38.31 38.21 37.84 37 36.59 32.27 

0.354838709677419 38.14 38.03 37.62 36.58 36.22 31.4 

0.387096774193548 36.84 36.71 36.38 35.9 35.19 30.79 
0.1 41.797 41.68 41.194 40.463 39.691 34.764 

Average of yearly averages: 26.5466 

Inputs generated by pe4.pl - 8-August-2003 

Data used for this run: 

Output File: kssorpropground 

Metf ile: w13996.dvf 

PRZM scenario: KSsorghumC.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Propazine 

Description Variable Name Value Units Comments 

Molecular weight mwt 230 g/mol 

Henry's Law Const. henry 1.02e-9 atm-mA3/mol 

Vapor Pressure vapr 2.9e-8 torr 

Solubility sol 8.6 mg/L 

Kd Kd mg/L 

Koc Koc 125 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 960 days Halfife 

Anaerobic Aquatic Metabolism kbacs 112 days Halfife 

Aerobic Soil Metabolism asm 480 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method: CAM 2 integer See PRZM manual 

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 1.344 kg/ha 

Application Efficiency: APPEFF .99 fraction 

Spray Drift DRFT .01 fraction of application rate applied to pond 

Application Date Date 10-5 dd/mm or dd/mmm or dd-mm or dd-mmrn 

Record 17: FILTRA 

IPSCND 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of 

entire run) 
Texas Sorghum Crop Scenario 

Aerial Spray Application of Propazine 4L 

stored as txsorpropaerial.out 

Chemical: Propazine 

PRZM environment: TXsorghumC.txt modified Satday, 12 October 2002 at 

17:29:00 

EXAMS environment: pond298.exv modified Thuday, 24 July 2003 at 10:02:00 

Metfile: w13958.dvf modified Wedday, 3 July 2002 at 09:06:24 

Water segment concentrations (ppb) 

Year 

19 6 1 

1962 

1963 

1964 

19 6 5 

19 6 6 

1967 

19 6 8 

1969 

1970 

1971 

1972 

1973 

1974 

1975 

1976 

19 7 7 

1978 

1979 

1980 

1981 

1982 

1983 

1984 

1985 

1986 

1987 

1988 

1989 

1990 

Peak 96 hr 21 Day 60 Day 90 Day Yearly 

6.805 6.776 6.686 6.45 6.336 3.85 

14.84 14.77 14.52 13.96 13.56 9.491 

13.18 13.13 12.95 12.82 12.59 10.92 

14.31 14.25 14.04 13.76 13.53 11.19 

41.58 41.47 40.74 39.36 38.26 25.68 

42.1 41.95 41.4 40.15 39.25 32.82 

33.32 33.22 32.9 31.96 31.49 28.69 

48.06 47.87 47.2 45.62 44.54 34.66 

46.82 46.66 46.12 44.74 43.63 37.11 

58.2 57.98 57.22 55.34 53.91 42.69 

41.95 41.89 41.63 41.07 40.64 37.22 

104 104 103 99.16 96.42 67.01 

73.09 73 72.63 71.83 71.15 64.45 

78.86 78.56 77.35 74.79 73 60.98 

60.18 60.06 59.55 58.22 57.16 52.88 

64.81 64.59 64.07 62.23 60.8 50.92 

48.08 48.02 47.81 47.31 46.87 42.93 

70.02 69.73 68.98 67.01 65.27 50.04 

87.73 87.42 86.11 83.21 81.12 65.28 

72.42 72.24 71.72 69.67 67.97 61.1 

58.54 58.37 57.93 57.09 55.98 50.13 

60.96 60.74 59.87 57.91 56.39 47.31 

71.54 71.26 70.52 68.36 66.68 53.51 

51.79 51.72 51.46 50.87 50.36 45.48 

37.53 37.43 37.05 36.64 36.28 33.21 

103 102 101 96.86 94.4 64.85 

73.35 73.16 72.45 71 69.64 64.61 

54.95 54.81 54.25 53.33 52.54 48.76 

64.51 64.34 63.56 61.65 60.19 48.69 

80.04 79.7 78.38 75.61 73.56 58.22 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 104 104 103 99.16 96.42 67.01 

0.0645161290322581 103 102 101 96.8694.4 65.28 

0.0967741935483871 87.73 87.42 86.11 83.21 81.12 64.85 

0.129032258064516 80.04 79.7 78.38 75.61 73.56 64.61 

0.161290322580645 78.86 78.56 77.35 74.79 73 64.45 

0.193548387096774 73.35 73.16 72.63 71.83 71.15 61.1 

0.225806451612903 73.09 73 72.45 71 69.64 60.98 

0.258064516129032 72.42 72.24 71.72 69.67 67.97 58.22 

0.290322580645161 71.54 71.26 70.52 68.36 66.68 53.51 

0.32258064516129 70.02 69.73 68.98 67.01 65.27 52.88 

0.354838709677419 64.81 64.59 64.07 62.23 60.8 50.92 

0.387096774193548 64.51 64.34 63.56 61.65 60.19 50.13 
0.1 86.961 86.648 85.337 82.45 80.364 64.826 

Average of yearly averages: 43.4893666666667 

Inputs generated by pe4.pl - 8-August-2003 

Data used for this run: 

Output File: txsorpropaerial 

Metf ile: w13958.dvf 

PRZM scenario: TXsorghumC.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Propazine 

Description Variable Name Value Units Comments 

Molecular weight mwt 230 g/mol 

Henry's Law Const. henry 1.02e-9 atm-mA3/mol 

Vapor Pressure vapr 2.9e-8 torr 

Solubility sol 8.6 mg/L 

Kd Kd mg/L 

Koc Koc 125 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 960 days Halfife 

Anaerobic Aquatic Metabolism kbacs 112 days Halfife 

Aerobic Soil Metabolism asm 480 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method : CAM 2 integer See PRZM manual 

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 1.344 kg/ha 

Application Efficiency: APPEFF .95 fraction 

Spray Drift DRFT .05 fraction of application rate applied to pond 

Application Date Date 01-5 dd/rnrn or dd/mrnrn or dd-rnrn or dd-mmm 

Record 17: FILTRA 

I PSCND 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of 

entire run) 
Texas Sorghum Crop Scenario 

Ground Spray Application of Propazine 4L 

stored as txsorpropground.out 

Chemical: Propazine 

PRZM environment: TXsorghumC.txt modified Satday, 12 October 2002 at 

17 : 29 : 00 

EXAMS environment: pond298.exv modified Thuday, 24 July 2003 at 10:02:00 

Metfile: w13958.dvf modified Wedday, 3 July 2002 at 09:06:24 

Water segment concentrations (ppb) 

Year 

19 6 1 

1962 

1963 

1964 

1965 

19 6 6 

1967 

1968 

1969 

1970 

1971 

1972 

1973 

1974 

1975 

1976 

1977 

1978 

1979 

1980 

1981 

1982 

1983 

1984 

1985 

19 8 6 

1987 

1988 

1989 

1990 

Peak 96 hr 21 Day 60 Day 90 Day Yearly 

4.561 4.542 4.481 4.321 4.204 2.516 

11.21 11.15 10.96 10.51 10.2 6.823 

8.273 8.249 8.147 8.009 7.917 7.313 

8.535 8.504 8.379 8.306 8.227 6.94 

36.61 36.5 35.83 34.55 33.56 21.51 

36.6 36.47 35.99 34.9 34.1 28.58 

27.42 27.34 27.11 26.31 25.83 24.07 

42.44 42.26 41.66 40.24 39.22 30.07 

40.92 40.78 40.32 39.12 38.16 32.48 

52.81 52.6 51.91 50.18 48.87 38.22 

37.99 37.93 37.7 37.19 36.8 32.52 

101 100 99.43 95.79 93.11 63.63 

70.49 70.41 70.05 69.28 68.62 60.86 

74.22 73.94 72.8 70.38 68.63 57.22 

54.7 54.58 54.15 52.98 52.34 48.69 

59.49 59.29 58.79 57.11 55.79 46.6 

44.11 44.06 43.86 43.4 43 38.21 

64.87 64.6 63.83 62.03 60.41 45.75 

83.5 83.2 81.94 79.15 77.15 61.6 

67.4 67.24 66.75 64.86 63.27 57.29 

53.13 52.98 52.63 51.82 50.84 45.95 

55.68 55.47 54.68 52.88 51.49 43.09 

66.68 66.42 65.76 63.74 62.16 49.52 

48.24 48.18 47.94 47.38 46.91 41.14 

33.21 33.17 33 32.62 32.31 28.39 

99.16 98.67 97.29 93.49 91.01 61.42 

68.84 68.75 68.36 67.5 66.84 61.14 

50.67 50.6 50.33 49.74 49.26 44.6 

59.46 59.31 58.57 56.76 55.43 44.59 

75.53 75.21 73.95 71.33 69.39 54.57 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Year 1 y 

0.032258064516129 101 100 99.43 95.79 93.11 63.63 

0.0645161290322581 99.16 98.67 97.29 93.49 91.01 61.6 

0.0967741935483871 83.5 83.2 81.94 79.15 77.15 61.42 

0.129032258064516 75.53 75.21 73.95 71.33 69.39 61.14 

0.161290322580645 74.22 73.94 72.8 70.38 68.63 60.86 

0.193548387096774 70.49 70.41 70.05 69.28 68.62 57.29 

0.225806451612903 68.84 68.75 68.36 67.5 66.84 57.22 

0.258064516129032 67.4 67.24 66.75 64.86 63.27 54.57 

0.290322580645161 66.68 66.42 65.76 63.74 62.16 49.52 

0.32258064516129 64.87 64.6 63.83 62.03 60.41 48.69 

0.354838709677419 59.49 59.31 58.79 57.11 55.79 46.6 

0.387096774193548 59.46 59.29 58.57 56.76 55.43 45.95 
0.1 82.703 82.401 81.141 78.368 76.374 61.392 

Average of yearly averages: 39.5100666666667 

Inputs generated by pe4.pl - 8-August-2003 

Data used for this run: 

Output File: txsorpropground 

Metf ile: w13958.dvf 

PRZM scenario: TXsorghumC.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Propazine 

Description Variable Name Value Units Comments 

Molecular weight mwt 230 g/mol 

Henry's Law Const. henry 1.02e-9 atm-mA3/mol 

Vapor Pressure vapr 2.9e-8 torr 

Solubility sol 8.6 mg/L 

Kd Kd mg/L 

Koc Koc 125 mg/L 

Photolysis half-life kdp 0 days Half-life 

Aerobic Aquatic Metabolism kbacw 960 days Halfife 

Anaerobic Aquatic Metabolism kbacs 112 days Halfife 

Aerobic Soil Metabolism asm 480 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method : CAM 2 integer See PRZM manual 

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 1.344 kg/ha 

Application Efficiency: APPEFF .99 fraction 

Spray Drift DRFT .01 fraction of application rate applied to pond 

Application Date Date 01-5 dd/mm or dd/mmrn or dd-mm or dd-rnmm 

Record 17: FILTRA 

I PSCND 

UPTKF 

Record 18: PLVKRT 

PLDKRT 

FEXTRC 0.5 

Flag for Index Res. Run IR Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of 

entire run) 
Appendix D. T-REX Model and Results 


Upper Bound Kenaga Residues 

For RQ Calculation 

Endpoints 






Appendix E. TerrPlant Model and Results 
Terrestrial Plant EECs and Acute Non Endangered RQs 

(November 9, 2005; version 1.2.1) 

Input 

Values 

a.i Jacre) 

Runoff Value 

(0.01,0.02, or 0.05 if 

chemicat solubility 

el 0,lO-100, or >I00 

ppm, respectively) 

l----L4 Minimum 

Incorporation Depth 

(inches) 

Seed Emerg 

Monocot EC25 (Ib 

a.i Jacre) 

Seed Emerg Dicot 

EC25 (N, a.i.lacre) 

Veg Vigor Monocot 

EC25 (Ib a.iJacre) 

Chemical: Propazine 4L 

- 

Estimated Environmental Concentrations (EECs) for 

NON-GRANULAR formulation applications (Ibs 

a.i./acre) 

0.035 

0.016 

0.046 

Application 

Method 

Ground 

Unincorp. 

Ground 

lncorp 

Risk Quotients (RQs) for NON-GRANULAR formulation 

applications 

Airblast, 

Chemigation 

Total 

Loading 

to 

Adjacent 

Areas 

(EEC = 

Sheet 

Runoff 

+Drift) 

0.0240 

0.0240 

Total 

Loading to 

Semiaquatic 

Areas (EEC 

- 

Channelized 

Runoff + 

Drift) 

0.1 320 

0.1 320 

Drift RQs 

RQ = Drift 

EEC/Most 

Sensitive EC25 

Emergence RQs, 

Adjacent Areas 

RQ = 

EECISeedling 

Emergence EC25 

DRIFT EEC 

(for 

ground: 

application 

rate x 0.01) 

(for aerial: 

application 

rate x 0.05) 

0.01 20 

0.01 20 

Monocot 

0.34 

0.34 

Emergence RQs, 

Semi-aquatic 

Areas 

RQ = EECISeedling 

Emergence EC25 

Monocot 

0.69 

0.69 

Dicot 

0.75 

0.75 

Monocot 

3.77 

3.77 

Dicot 

1.50 

1.50 

Dicot 

8.25 

8.25 
Terrestrial Plant EECs and Acute Non Endangered RQs 

(November 9,2005; version 1.2.1) 

Input 

Values 

Chemical: Propazine 4L 
Minimum 

Incorporation 

(inches) 

Terrestrial Plant EECs and Acute Endangered RQs 

(November 9, 2005; version 1.2.1) 

Input 

Values 

Seed Emerg c0.01 

Monocot 

EC05 or 1 NOAEC (Ib 

Application 

Rate (Ib 

a.i.lacre) 

Runoff Value 

(0.01,0.02, or 

0.05 if 

chemical 

solubility 

40, 10-100, 

or >I00 ppm, 

respectively) 

a.i.1acre) 

Dicot ECOS 

1.2 

0.01 

Veg Vigor 

Monocot 

EC05 or 

NOAEC (Ibs 

Chemical: Propazine 4L 

Estimated Environmental Concentrations (EECs) for 

NON-GRANULAR formulation applications (lbs 

a.i Jacre) 

Application 

Method 

Ground 

Unincorp. 

Ground 

lncorp 

Aerial, 

Airblast, 

spray 

Chemigation 

Risk Quotients (RQs) for NON-GRANULAR formulation 

applications 

Total 

Loading 

to 

Adjacent 

Areas 

(EEC = 

Sheet 

Runoff + 

Drift) 

0.0240 

0.0240 

0.0720 

Emergence RQs, 

Adjacent Areas 

RQ = EEClSeedling 

Emergence EC05 or 

NOAEC 

Total 

Loading to 

Semi-aquatic 

Areas (EEC = 

(Channelized 

Runoff + 

Drift) 

0.1 320 

0.1 320 

0.1 800 

Monocot 

>2.40 

~2.40 

>7.20 

DRIFT EEC 

(for 

ground: 

application 

rate x 0.01) 

(for aerial: 

application 

rate x 0.05) 

0.01 20 

0.0120 

0.0600 

Dicot 

5.1 1 

5.1 1 

15.32 

Emergence 

RQs, Semiaquatic areas 

RQ = EECISeedling 

Emergence 

EC05 or NOAEC 

Monocot 

>13.20 

13.20 

>18.00 

Drift RQs 

RQ = EECIMost 

Sensitive EC05 

or NOAEC 

Dicot 

28.09 

28.09 

38.30 

Monocot 

>1.20 

>1.20 

>6.W 

Dicot 

2.55 

2.55 

12.77 

Appendix F. Ecological Effects Data 
71-1 Avian Acute Oral 

Bobwhite Quail. MRID 442873-01 (Core). Propazine was tested in a single oral gavage study 

with bobwhite quail (5lsexldose at nominal concentrations of 0, 0 (vehicle control), 260,430, 

720, 1200 or 2000 mg/kg bw with a 14-day observation period). Propazine was determined to be 

slightly toxic to bobwhite quail with an LD50 of >1,640 mg ailkg, the highest dose tested when 

corrected for % active ingredient. At the 1200 mg/kg dose level, only 4 females were tested. 

Transient decreases in body weight and food consumption were observed at 430 mag bw and 

above. The NOAEL was determined to be 244 mg ailkg due to weight loss up to 72 hours after 

treatment. The study is scientifically sound and fulfills the guideline requirements. 

71-2 Avian Subacute Dietary 

Bobwhite Quail. MRID 442873-02 (Core). In an 8-day dietary study, propazine was determined 

to be slightly toxic to bobwhite quail with an LC5() >4,930 ppm ai (nominal concentration). A 

NOAEL was not determined. Diminished feed consumption, slow growth, and cannibalism is 

attributed to a possible chemical-induced anorexia. The study is scientifically sound and fulfills 

guideline requirements. 

Mallard. MRID 442873-03 (Core). In an 8-day dietary study, propazine was determined to be 

practically non-toxic to mallard ducklings with an LCs0 >5,140 ppm ai (nominal concentration). 

A NOAEL was not determined. Feed consumption rates and resultant growth indicated a 

chemically-induced anorexia. The study is scientifically sound and fulfills guideline 

requirements. 

72-1 Freshwater Fish Acute 

Bluegill Sunfish. MRID 442873-04 (Invalid). In a 96-hour flow-through test, the reported LCs0 

and NOAEL of >4.5 mg ai/L may overestimate the toxicity due to the limited solubility of 

propazine. Precipitate in the higher treatment levels raises a question of actual exposure and 

bioavailability. Erratic swimming behavior in fish treated with 1.0 and 1.8 mg/L of propazine 

may represent a compound-related affect in treatments where propazine was freely soluble. The 

study is not scientifically sound and does not meet guideline requirements. 

72-2 Freshwater Invertebrate Acute 

Daphnia. MRID 442873-05 (Uncertain). In a 48-hour flow-through test, propazine was 

determined to be moderately toxic to daphnids with an ECso of >5.32 ppm ai (mean measured 

concentration). The NOAEC was determined to be 5.32 ppm ai. The study is scientifically 

sound but does not fulfill guideline requirements because daphnids were not exposed up to 100 

ppm ai. If it can be shown that the test was conducted up to the limit of solubility, the study may 

be upgraded to acceptable. This study was originally classified as supplemental; however, it was 

reevaluated in 2005 and is awaiting EFED validation. 

72-3b EstuarineIMarine Invertebrate Acute 

Eastern Oyster. MRID 442873-06 (Uncertain). In a 96-hour flow-through test, propazine was 

determined to be practically non-toxic to the eastern oyster at the limit of water solubility with an 

EC50 of >3.72 mg ai/L (mean measured concentration). The NOAEC was determined to be 3.72 

mg ai/L. No significant adverse effects were observed on shell deposition. The study is 
scientifically sound and fulfills guideline requirements. This study was originally classified as 

invalid due to limited solubility of propazine; however, it was reevaluated in 2006 and EFED 

established the reported values (classification awaiting EFED validation). 

Saltwater Mysid. MRID 441 848-01 (Acceptable). In a 96-hour static test, propazine was 

determined to be moderately toxic to saltwater mysid with an of 4.20 ppm ai (mean 

measured concentration), based on mortality and sublethal effects. The NOAEC was determined 

to be 0.586 ppm ai. The study is scientifically sound and fulfills guideline requirements. 

72-4a Freshwater Fish Early Life Stage 

Fathead Minnow. MRID 442873-07 (Supplemental). In an early life-stage flow-through test, 

propazine produced significant reduction in length. The NOAEL was determined to be 0.72 mg 

ai/L). The MATC was calculated at 0.938 mg ai/L. The study is scientifically sound, but does 

not fulfill guideline requirements since both pH and hardness exceeded recommended levels 

potentially affecting solubility. 

72-4b Freshwater Invertebrate Life Cycle 

Daphnia. MRID 443276-02 (Core). In a life cycle flow-through test, the NOAEC and LOAEC 

were determined to be 0.047 ppm ai mg/L and 0.091 ppm ai, respectively, based on growth 

measured in terms of length (mm) and weight (g). The study is scientifically sound and fulfills 

guideline requirements. 

72-4c EstuarineIMarine Fish Life Cycle 

Sheepshead Minnow. MRID 441 848-02 (Uncertain). In a 36-day chronic flow-through test, 

propazine was determined to affect embryo survival and hatching success in early life-stage 

sheepshead minnow with an NOAEC of 1.34 mg ai/L (mean measured concentration). The 

LOAEC was determined to be 2.59 mg ai/L. The study is scientifically sound and meets 

guideline protocols. This study was reevaluated in 2006 and EFED disagreed with the study 

author's conclusion and modified the results (classification awaiting EFED validation). 

72-4d EstuarineIMarine Invertebrate Life Cycle 

Saltwater Mysid. MRID 441 848-03 (Supplemental). In a 28-day life cycle test under flowthrough conditions, propazine produced significant effects on growth (dry weight, combined and 

separate sexes) and reproduction. The NOAEC and LOAEC were 0.269 and 0.706 ppm ai 

(mean measured concentrations), respectively. The study is scientifically sound; however, since 

second-generation mysids were not maintained for at least 4 days and observed for survival, 

development and behavior, the study does not fulfill guideline requirements. 

81-1 Acute Mammalian Oral 

Rat. MRID 434741-01 (Core). In an acute oral study, propazine was determined to have be 

practically non-toxic (Toxicity Category IV) to rats with an LDS0 of >5050 mglkg. The study is 

scientifically sound and fulfills guideline requirements. 

83-3 Mammalian Developmental 
Rat. MRID 001 502-42 (Core). In a developmental toxicity study with Sprague-Dawley rats, 

propazine produced maternal and developmental toxicity. The maternal NOAEL was 10 

mglkglday (LOAEL = 100 mglkglday) based upon decreased body weights and food 

consumption. Salivation was also reported at doses 2500 mgkglday. The developmental 

NOAEL was 10 mgkglday (LOAEL = 100 mgkglday) based on decreased ossification. This 

study is scientifically sound and fulfills guideline requirements. 

Rabbit. MRID 441534-01 (Core). In a developmental toxicity study with New Zealand White 

rabbits, propazine produced maternal toxicity. No developmental toxicity was observed. The 

maternal NOAEL was 10 mgkglday (LOAEL = 50 mgkglday) based upon decreased defecation 

and decreased body weight gain and food consumption. This study is scientifically sound and 

fulfills guideline requirements. 

83-4 Mammalian Reproduction 

Rat. MRID 0004 14 1-09 (Core). In a 3 -generation reproduction study, propazine produced 

parentalloffspring toxicity with a NOAEL of 5 mgfkglday (100 ppm) and the LOAEL of 50 

mglkglday (1 000 ppm) based upon body weight decrements in males and females. No 

reproductive toxicity was observed; consequently, the NOAEL was 250 mgkglday (21000 ppm) 

and the LOAEL was >50 mglkglday (> 1000 pprn). This study is scientifically sound and fulfills 

guideline requirements. 

122-2 Aquatic Plant Algae 

Blue-green algae. MRID 442873-12 (Core). In a Tier I1 toxicity test with AnabaenaJlos-aquae, 

the 7 day ECso for cell density was 0.18 pprn ai (NOAEC = 0.068 pprn ai). The study is 

scientifically sound and fulfills the guideline requirements. 

Green algae. MRID 442873-08 (Core). In a Tier I1 toxicity test with Selenastrum 

capricornutum, the 7 day ECso for cell density was 0.029 pprn ai (NOAEC = 0.012 pprn ai). The 

study is scientifically sound and hlfills the guideline requirements. 

Marine diatom. MRID 442873-1 1 (Core). In a Tier I1 toxicity test with Skeletonema costatum, 

the 7 day ECSO for cell density was 0.025 pprn ai (NOAEC = 0.01 7 pprn ai). The study is 

scientifically sound and fulfills the guideline requirements. 

Diatom. MRID 442873-10 (Core). In a Tier I1 toxicity test with Naviculapelliculosa, the 7 day 

ECS0 for cell density was 0.0248 pprn ai (NOAEC = 0.0065 pprn ai). The study is scientifically 

sound and hlfills the guideline requirements. 

123-l(a) Seedling Emergence - Tier I1 

Monocots (5 species) and Dicots (6 species). MRID 441 848-04 (Uncertain). In a Tier I1 

seedling emergence study, percent emergence, shoot weight and shoot length were affected in all 

species tested (cabbage, corn, cucumber, lettuce, oats, onion, ryegrass, radish, soybean, tomato 

and wheat) with shoot weight being the most sensitive parameter tested. Onion was the most 

sensitive monocot species (EC2S 0.035 lb ailA, NOAEC <0.010 lb ai/A) and lettuce was the most 

sensitive dicot species (EC2S 0.016 lb ai/A, NOAEC <0.0047 lb ai/A). With the exception of 

corn and ryegrass, all species exhibited phytotoxic effects, including chlorosis, necrosis, stunting 
and mortalities. This study was reevaluated in 2006 and additional statistical analyses were 

performed (classification awaiting EFED validation). 

123-l(b) Vegetative Vigor - Tier I1 

Monocots (5 species) and Dicots (6 species). MRID 441 848-04 (Uncertain). In a Tier I1 

vegetative vigor study, shoot weight and shoot height were affected in all species tested 

(cabbage, cucumber, lettuce, oats, onion, ryegrass, radish, soybean, tomato and wheat), with the 

exception of corn. Shoot weight was the most sensitive parameter tested with wheat being the 

most sensitive monocot species (EC25 0.046 lb ai/A, NOAEC C0.020 lb ai/A). Cucumber was 

the most sensitive dicot species (EC25 0.010 lb ai/A, NOAEC ~0.075 lb ai/A). With the 

exception of tomato and soybean, all species exhibited phytotoxic effects, including chlorosis, 

necrosis, stunting and mortalities. This study was reevaluated in 2006 and additional statistical 

analyses were performed (classification awaiting EFED validation). 

123-2 Aquatic Plant Acute 

Duckweed. MRID 442873-09 (Core). In a Tier I1 toxicity test with Lemna gibba, the 7 day EC50 

for cell density was 0.10 ppm ai (NOAEC = 0.022 ppm ai). The study is scientifically sound and 

fulfills the guideline requirements. 

141-1 Acute Contact Toxicity Test to Honey Bees 

In an acute contact study with the honey bee, propazine was determined to be relatively nontoxic. At 96 hours, mortality was 2.47% at a dose of 96.69 pg/bee (Atkins et al. 1975). A belljar vacuum duster was used to apply the pesticide, mixed with a pyrolite dust diluent and given 

to the test bees. Dosages of the dust were weighed, bees were aspirated into dusting cages and 

treated, and then bees were transferred into holding cages. Observations were recorded at 12,24, 

48, 72 and 96 hours. The study was scientifically sound and showed that propazine is relatively 

non-toxic to honey bees. The study fulfills the guideline requirement for an acute contact 

toxicity test on honey bees. 
Appendix G. The Risk Quotient Method and Levels of Concern 
The risks to terrestrial and aquatic organisms are determined based on a method by which risk 

quotients (RQs) are compared with levels of concern (LOCs). This method provides an 

indication of a chemical's potential to cause an effect in the field from effects observed in 

laboratory studies, when used as directed. Risk quotients are expressed as the ratio of the 

estimated environmental concentration (EEC) to the species-specific toxicity reference value 

(TRV): 

EEC 

RQ= - 

TR V 

Units for EEC and TRV should be the same (e.g., pg1L or ppb). The RQ is compared to the 

LOC as part of a risk characterization. Acute and chronic LOCs for terrestrial and aquatic 

organisms are given in recent Agency guidance (EPA, 2004) and summarized in the table below. 

Level of concern (LOC) by risk presumption category (U.S. EPA 2004). 

Risk Presumption RQ LOC 

Acute Risk a 

Acute Restricted Use " 

Acute Endangered Species ' 

Chronic Risk 

Acute Risk 

Acute Restricted Use 

Acute Endangered Species 

Chronic Risk 

Acute Risk 

Acute Endangered Species 

Acute Risk 

Acute Endangered Species 

Mammals and Birds 

EEC~ILC~~ or LDSO/sqftc or LDsdday 

EECILCSO or LDsOlsqft or LDSdday (or LDso 40 mglkg) 

EEC/LCSO or LDS0/sqft or LDsdday 

EEC/NOAEC 

Aquatic Animals 

EECYLCSO or ECsO 

EEC/LCSo or ECso 

EEC/LCSo or ECsO 

EECrnOAEC 

Terrestrial and Semi-aquatic Plants 

EECIEC25 

EEC/ECos or NOAEC 

Aquatic Plants 

EEC~IEC~~ 

EECYECOs or NOAEC 

'Potential for acute toxicity for receptor species if RQ > LOC (EPA, 2004). 

h~sti~natednvironmental concentration (pp~n) on aviadmamtnalian food items 

'mg!ft2 

"mg of toxicant consumed per day 

'Potential for acute toxicity for receptor species, even considering restricted use classification, if RQ > LOC (EPA, 2004). 

'Potential for acute toxicity for endangered species of receptor species if RQ > LOC (EPA, 2004). 

gEEC = ppb or ppm in water 

"EEC = Ibs a.i.1A 

The LOCs are criteria used by OPP to indicate potential risk to non-target organisms and the 

need to consider regulatory action. The criteria indicate that a pesticide used as directed has 

the potential to cause adverse effects on non-target organisms. LOCs currently address the 

following risk presumption categories: (I) acute - potential for acute risk to non-listed 

species; regulatory action may be warranted in addition to restricted use classification, (2) 

acute restricted use - potential for acute risk to non-listed species; however, risk may be 

mitigated through restricted use classification, (3) acute endangered species - potential for 
acute risk to endangered species; regulatory action may be warranted, and (4) chronic risk - 

potential for chronic risk; regulatory action may be warranted. Currently, due to lack of 

modeling applications, EFED does not perform assessments for chronic risk to plants, acute 

or chronic risks to non-target insects or chronic risk from granularhait formulations to 

mammalian or avian species. 

For acute studies on taxa where no effects were observed at any concentration level, the RQs 

are not calculated and a qualitative discussion is provided in the Risk Description section. 

For acute studies on taxa where an LCsO/LDsO is not established due to insufficient mortality 

but some mortality was observed in the study, again, the RQs are not calculated and the study 

is discussed further in the Risk Description section. 

The ecotoxicity test values (i.e., measurement endpoints) used in the acute and chronic risk 

quotients are derived from the results of required studies. Examples of ecotoxicity values 

derived from the results of short-term laboratory studies that assess acute effects are: (1) LCso 

(fish) (2) LD50 (birds and mammals) (3) EC50 (aquatic plants and aquatic invertebrates) and 

(4) EC25 (terrestrial plants). An example of a toxicity test effect level derived from the 

results of long-term laboratory study that assesses chronic effects is: NOAEC (No Observed 

Adverse Effect Level; birds, fish and aquatic invertebrates). 
Appendix H. Data Requirements 
I. 

Guideline 

# 

161-1 

161-2 

161-3 

161-4 

162- 1 

162-2 

162-3 

162-4 

163-1 

163-2 

163-3 

1 64- 1 

164-2 

165-4 

165-5 

1 66- 1 

TABLE H-1. Environmental 

Data Requirement 

Hydrolysis 

Photodegradation in 

Water 

Photodegradation on 

Soil 

Photodegradation in Air 

Aerobic Soil 

Metabolism 

Anaerobic Soil 

Metabolism 

Anaerobic Aquatic 

Metabolism 

Aerobic Aquatic 

Metabolism 

LeachingAdsorption/Desorption 

Laboratory Volatility 

Field Volatility 

Terrestrial Field 

Dissipation 

Aquatic Field 

Dissipation 

Accumulation in Fish 

Aquatic non-target 

organism 

Ground Water- small 

scale prospective 

Fate Data 

MRID # 

436898-02 

44 1848-05 

00 1537-09 

44 1848-06 

No Study 

44 1848-07 

001537-12 

001537-13 

No Study 

No Study 

436898-03 

436898-04 

442873-1 3 

00 1529-97 

No Study 

No Study 

442873-14 

44 1848-09 

001537-15 

001537-16 

001537-17 

001537-18 

No Study 

44184812 

No Study 

No Study 

Requirements for Propazine 

Study 

Classification 

Acceptable 

Acceptable 

Supplemental 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Supplemental 

Supplemental 

Unacceptable 

Unacceptable 

Unacceptable 

Unacceptable 

Avaiting final 

EFED review 

Are more 

data needed? 

No 

No 

No 

No 

No 

Yes 

Yes 

NO 

Yes 

?? 
71-4 

72- 1 

72-2 

72-3a 

72-3b 

72-4a 

72-4b 

72-4c 

72-4d 

72-5 

72-7 

- 

81-1 

82- l (a) 

83-3 

83-4 

123- l (a) 

123- l (b) 

122-2 

(bobwhite quail) 

(mallard duck) 

Avian reproduction 

(bobwhite quail) 

(mallard duck) 

Freshwater fish acute LCjo0 

(rainbow trout) 

(bluegill sunfish) 

Freshwater invertebrate acute ECjO 

(daphnia) 

Estuarinelmarine fish acute LCjo 

(sheepshead minnow) 

Estuarineimarine invertebrate acute 

ECjo 

(eastern oyster) 

(mysid) 

Freshwater fish early life stage 

(fathead minnow) 

Freshwater invertebrate life cycle 

(daphnia) 

Estuarineimarine fish life cycle 

(sheepshead minnow) 

Estuarinelmarine invertebrate life 

cycle 

(mysid) 

Freshwater fish full life cycle 

Aquatic Field Study 

~p - 

Acute mammalian oral LDSO 

(rat) 

Mammalian Subchronic 

Mammalian Develop~nental 

(rat) 

(rabbit) 

Mammalian Reproduction 

(rat) 

Seedling Emergence - Tier ll 

Vegetative Vigor - Tier II 

Aquatic plant algae 

(green algae) 

(blue-green algae) 

(diatom) 

(marine diatom) 

442873-02 

442873-03 

N/ A 

NIA 

442873-04 

442873-05 

N/ A 

442873-06 

44 1848-01 

442837-07 

443276-02 

44 1848-02 

44 1848-03 

NIA 

NIA 

43474 1 -0 1 

NIA 

00 1502-42 

44 1534-0 1 

0004 14-09 

441 848-04 

44 1848-04 

442873-08 

442873- 12 

442873-1 0 

442873-1 1 

Core 

Core 

-- 

Invalid 

Awaitingfinal EFED 

review 

A waitingJinal EFED 

review 

Acceptable 

Supplemental 

Core 

Awaitingjt~al EFED 

review 

Supplemental 

Acceptable 

Acceptable 

Acceptable 

Acceptable 

Awaitingjnal EFED 

review 

Awaitingjnal EFED 

review 

Core 

Core 

Core 

Core 

No 

Yes 

Yes 

? ? 

Yes 

?? 

Yes 

No 

? ? 

Yes 

No 

No 

No 

? ? 

?? 

No 

Appendix I. Environmental Fate Bibliography 
Keller, A. 1979b. Degradation of propazine (Gesamil) in aerobic soil. Project Report No. 

15/79. Unpublished study prepared by Ciba-Geigy, Ltd., Basle, Switzerland. MRID 001537-12. 

Hughes, D. L. 1996. Field Soil Dissipation of Propazine (~ilo-~ro~~ 4L) on Bare Soil in North 

Carolina. Laboratory Project Identification CHW Study No. 664 1 - 100A. Unpublished study 

performed by Coming Hazelton Inc, Madison, WI, and submitted by Griffin Corporation, 

Valdosta, GA. MRID 442873-14. 

Hughes, D. L. 1996. Field Soil Dissipation of Propazine (~ilo-pro~~ 4L) on Bare Soil in 

Texas. Laboratory Project Identification CHW Study No. 6641 -1 00. Unpublished study 

performed by Coming Hazelton Inc, Madison, WI, and submitted by Griffin Corporation, 

Valdosta, GA. MRID 44 1848-09. 

Mobley, S. G. 1994. Solution Photolysis of [14~]~ropazinen Artificial Light. Laboratory Project 

ID No. 85 1 Report No. 1644. Unpublished study performed by PTRL East, Inc., Richmond, KY, 

and submitted by Griffin Corporation, Valdosta, GA. MRID 441848-05 

Mobley, S. G. 1994. Soil Surface Photolysis of [14~]~ropazinen Artificial Light. Laboratory 

Project ID No. 852 Report No. 1645. Unpublished study performed by PTRL East, Inc., 

Richmond, KY, and submitted by Griffin Corporation, Valdosta, GA. MRID 441848-06 

Perdue, D. 1994. Hydrolysis of ['4~]~ropazine i Aqueous Buffered Solutions at pH 5, 7 and 9. 

Project No. 850. Report No. 1640. Unpublished study performed by PTRL East, Inc., 

Richmond, KY, and submitted by Griffin Corporation, Valdosta, GA. MRID 436898-02. 

Perdue, D. 1995. Soil AdsorptiodDesorption of 2-~~drox~-['~~]~ro~azine by the Batch 

Equilibrium Method. Project No. 91 3. Report No. 1 8 17. Unpublished study performed by 

PTRL East, Inc., Richmond, KY, and submitted by Griffin Corporation, Valdosta, GA. MRID 

442873- 13. 

Perdue, D. 1995. Column Leaching of [14C]~ropazine in Four Soil Types Following Aerobic 

Aging. Project No. 855. Report No. 1660. Unpublished study performed by PTRL East, Inc., 

Richmond, KY, and submitted by Griffin Corporation, Valdosta, GA. MRID 436898-03. 

Perdue, D. 1995b. Soil AdsorptiodDesorption of [14~]~ropazine by the Batch Equilibrium 

Method. Project No. 853. Report No. 1653. Unpublished study performed by PTRL East, Inc., 

Richmond, KY, and submitted by Griffin Corporation, Valdosta, GA. MRID 436898-04. 

Perdue, D. 1995. Aerobic Soil Metabolism of [14~]~ropazine in Sandy Loam. Project No. 865. 

Report No.1661. Unpublished study performed by PTRL East, Inc., Richmond, KY, and 

submitted by Griffin Corporation, Valdosta, GA. MRID 441 848-07. 
Appendix J. Ecological Toxicity Bibliography 
Atkins, E.L., E.A. Greywood and R.L. MacDonald. 1975. Toxicity of pesticides and other 

agricultural chemicals to honey bees. University of California, Division of Agricultural Science 

Leaflet 2287. 38pp. FicheIMaster ID 00036935. 

Boeri, R.L., P.L. Kowalski, and T.J. Ward. 1995. Chronic toxicity of propazine to the mysid, 

mysidopsis bahia. Unpublished study performed by T.R. Wilbury Laboratories, Inc. 

Marblehead, MA. Laboratory Project ID No. 573-AB. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 441 848-03. 

Boeri, R.L., P.L. Kowalski, and T.J. Ward. 1995. Early life-stage toxicity of propazine to the 

sheepshead minnow, Cyprinodon variegates. Unpublished study performed by T.R. Wilbury 

Laboratories, Inc. Marblehead, MA and ABC Laboratories, Inc., Environmental Toxicology 

Division, Columbia, MO. Study submitted by Griffin Corporation, Valdosta, GA. MRID 

441 848-02. 

Boeri, R.L., P.L. Kowalski, and T.J. Ward. 1995. Flow through shell deposition test with 

propazine and the eastern oyster, Crassostrea virginica. Unpublished study performed by T.R. 

Wilbury Laboratories, Inc. Marblehead, MA and ABC Laboratories, Inc., Environmental 

Toxicology Division, Columbia, MO. Laboratory Project ID No. 41956. Study submitted by 

Griffin Corporation, Valdosta, GA. MRID 442873-06. 

Boeri, R.L., P.L. Kowalski, and T.J. Ward. 1995. Static acute toxicity of propazine to the 

mysid, mysidopsis bahia. Unpublished study performed by T.R. Wilbury Laboratories, Inc. 

Marblehead, MA. Laboratory Project ID No. 571 -AB. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 44 1848-01. 

Bowman, J. and J. Veltri. 1995. Acute toxicity of propazine to bluegill (Lepomis macrochirus). 

Unpublished study performed by ABC Laboratories, Inc., Environmental Toxicology Division, 

Columbia, MO. Laboratory Project ID No. 41953. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 442873-04. 

Gledhill, D. W. and J.B. Bussard. 1995. Acute toxicity of propazine to Anabaenaflos-aquae. 

Unpublished study performed by ABC Laboratories, Inc., Environmental Toxicology Division, 

Columbia, MO. Laboratory Project ID No. 41 968-9. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 442873- 12. 

Gledhill, D.W. and J.B. Bussard. 1995. Acute toxicity of propazine to Skeletonema costatum. 

Unpublished study performed by ABC Laboratories, Inc., Environmental Toxicology Division, 

Columbia, MO. Laboratory Project ID No. 41967. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 442873- 1 1. 

Hicks, S.L., J.B. Bussard, and D.W. Gledhill. 1995. Acute toxicity of propazine to Selenastrum 

capricornutum. Unpublished study performed by ABC Laboratories, Inc., Environmental 

Toxicology Division, Columbia, MO. Laboratory Project ID No. 41962. Study submitted by 

Griffin Corporation, Valdosta, GA. MRID 442873-08. 
Hicks, S.L. and D.W. Gledhill. 1995. Acute toxicity of propazine to Naviculapelliculosa. 

Unpublished study performed by ABC Laboratories, Inc., Environmental Toxicology Division, 

Columbia, MO. Laboratory Project ID No. 41966. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 442873-10. 

Hicks, S.L., Gledhill, D.W. and J. Veltri. 1995. 14-Day static toxicity of propazine to Lemna 

gibba. Unpublished study performed by ABC Laboratories, Inc., Environmental Toxicology 

Division, Columbia, MO. Laboratory Project ID No. 41963. Study submitted by Griffin 

Corporation, Valdosta, GA. MRID 442873-09. 

Jameson, C.E. and J. Veltri. 1995. Acute dietary toxicity of propazine to bobwhite quail 

(Colinus virginianus). Unpublished study performed by ABC Laboratories, Inc., Environmental 

Toxicology Division, Columbia, MO. Laboratory Project ID No. 41758. Study submitted by 

Griffin Corporation, Valdosta, GA. MRID 442873-02. 

Jameson, C.E. and J. Veltri. 1995. Acute dietary toxicity of propazine to mallard ducks (Anas 

platyrhynchos). Unpublished study performed by ABC Laboratories, Inc., Environmental 

Toxicology Division, Columbia, MO. Laboratory Project ID No. 41759. Study submitted by 

Griffin Corporation, Valdosta, GA. MRID 442873-03. 

Jameson, C.E. and J. Veltri. 1995. Acute oral toxicity of propazine to bobwhite quail (Colinus 

virginianus). Unpublished study performed by ABC Laboratories, Inc., Environmental 

Toxicology Division, Columbia, MO. Laboratory Project ID No. 4 1757. Study submitted by 

Griffin Corporation, Valdosta, GA. MRID 442873-01. 

Jessup, D.C. et al. 1979. Three generation reproduction study in rats. International Research 

and Development Corporation, Mattawan, MI. Report No. 382-010. Study submitted by CibaGeigy Corporation. MRID 00041 4-09. 

Knapp, J.F. 1995. A developmental toxicity study of propazine technical in rabbits. WIL 

Research Laboratories, Inc., Ashland, Ohio. Laboratory Study No. WIL-157005. Study 

submitted by Griffin Corporation, Valdosta, GA. MRID 441 534-01. 

Kuhn, J.O. 1994. Acute oral toxicity of propazine to Sprague-Dawley rats. Unpublished study 

performed by Stillmeadow, Inc. Laboratory Study No. 13 18-94. Study submitted by Griffin 

Corporation, Valdosta, GA. MRID 43474 1-0 1. 

Murrell, H.R. 1994. Acute toxicity of propazine to Daphnia magna. Unpublished study 

performed by ABC Laboratories, Inc., Environmental Toxicology Division, Columbia, MO. 

Laboratory Project ID No. 41954. Study submitted by Griffin Corporation, Valdosta, GA. 

Definitive study conducted September 21 - 23, 1994. MRID 442873-05. 

Murrell, H.R. and J. L. Veltri. 1997. Chronic toxicity of propazine to Daphnia magna under 

flow-through conditions. Unpublished study performed by ABC Laboratories, Inc., 
Environmental Toxicology Division, Columbia, MO. Laboratory Project ID No. 41 958. Study 

submitted by Griffin Corporation, Valdosta, GA. MRID 443276-02. 

Rhodes, J.E. 1995. Early life-stage toxicity of propazine to fathead minnows. Unpublished 

study performed by ABC Laboratories, Inc., Environmental Toxicology Division, Columbia, 

MO. Laboratory Project ID No. 41 957. Study submitted by Griffin Corporation, Valdosta, GA. 

MRID 442873-07. 

Salamon, C. 1985. Teratology study in albino rats with propazine technical. American 

Biogenics. Study 450-1788. Study submitted by Ciba-Geigy Corporation, MRID 001502-42. 

Schwab, D., L. Brian, and J. Veltri. 1996. Evaluating the effects of propazine on the emergence 

and vegetative vigor of non-target terrestrial plants. Study performed by ABC Laboratories, 

Columbia, MO. Laboratory Project ID No. 4 196 1. Study submitted by Griffin Corporation, 

Valdosta, GA. MRID 44 1 848-04.