UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, DC 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

PC Code: 108201 

DP Barcodes: 403093, 

403094,403095,403098,403099,and403100 

DECISION: 465091, 465086, 465089, 465090, 465092, 

465087 Date: November, 20, 2012 

MEMORANDUM 

Subject: Ecological Risk and Drinking Water Assessments for Proposed Label 

Amendments of Diflubenzuron 

To: Autumn Metzger, Risk Manager Reviewer 

John Hebert, Risk Manager 

Registration Division (7505P) 

From: ,-,_ ' ( f ~ t!/lolt2___ 

Faruque Khan, Ph.D., Senior Scient4"st- / ~ ~ '-- · . -

Approved 

By: 

Ste~hen Wente, ~h.D., Biologist ~7 -:"3 ( >---=?~_ 

Environmental Risk Branch I ~- ·· ' 

Environmental Fate and Effects Division (7507P) l( ) l 1 

!Cl M ICVv. (()~ .ltl J~ JEd_ Odenkirchen, Ph.D., Acting_ Br~ch (:hi~f ~ }'(c,. ~- \\.\ ~ o \ \.Y · 

Sujatha Sankula, Ph.D. Lead Bwlogist ,\...,_,.:.\'--- 1 ~---~ 

Environmental Risk Branch I 

Environmental Fate and Effects Division (7507P) 

The Environmental Fate and Effects Division (EFED) has conducted an ecological risk 

assessment and a drinking water assessment for human health in response to Chemtura 

Corporation's request for several amendments in the Micromite 80WG (EPA Reg. No. 400-

487), Diflubenzuron 90% Concentrate (EPA Reg. No. 400-466) and Dimilin® 2L(EPA Reg. 

No. 40-461) product labels. Label amendments for the above product labels include the 

following: 

• Add the entire citrus crop group (Crop Group 1 0-09), which replaces oranges, 

grapefruits, tangerines and pommelos 

• Reduce retreatment intervals from 90 days to 30 days 

• Allow low volume (3 to 5 gallon per acre) with spray nozzles that produce a droplet 

size of a volume median diameter (Dvo.s) of2: 90J.lm 

• An additional change in the Dimilin 2L (EPA Reg. No.400-461) label to include 

grasses/forages grown for biofuel, biomass or bioenergy production 
Proposed changes like reduced retreatment intervals and low volume application with 

spray nozzles that produce a droplet size of Dvo 5 of 2: 90J.!m may have implications on exposure 

assessment and consequently in the risk assessment. Ecological risk as well as drinking water 

assessment was performed to address label amendments requested by Chemtura Corporation. 

Potential risks to non-target organisms are summarized in Table 1. RQs exceeded the acute 

(RQ?:0.05) and chronic risk LOC (RQ?:l.O) for both listed and non-listed freshwater and 

estuarine/marine invertebrates only (Table 1). Risks were not identified for any other taxa. 

Potential risks to listed species based on location analysis due to the expanded use of 

diflubenzuron on citrus crop group and grasses/forages grown for biofuel, biomass/bioenergy 

production will be evaluated in the future Registration Review risk assessment for diflubenzuron. 

Table 1. Summary of Potential Risks for the Proposed Label Modification of 

Diflubenzuron 

Taxonomic Group 

Use Terrestrial Terrestrial Aquatic Aquatic Birds Mammals Fish Invertebrates Plants Invertebrates & Mollusks Plants 

Citrus Crop -- -- a -- -- ,jb -- --

• No toxicity data submitted for terrestrial plant by the registrant. Given the mode of action of diflubenzuron, 

effects are not anticipated on terrestrial plants. 

b Acute and chronic LOCs are exceeded for freshwater and estuarine/marine invertebrates 

Diflubenzuron and CPU Residue in Drinking Water Sources for Human Health 

The estimated drinking water concentrations (EDWCs) for diflubenzuron use on citrus 

are higher than the previously recommended annual mean (chronic/non cancer) and 30 year 

average (chronic/cancer) concentrations for surface water. Therefore, the currently calculated 

EDWCs (3.47J.lg /L for the peak (acute) concentration, 0.26 J.lg /L for the annual mean 

(chronic/non cancer) concentration, and 0.12 J.lg /L for the 30 year average concentration 

(chronic/cancer) are recommended for diflubenzuron. 

The current EDWCs of 4-chlorophenyl urea (CPU) for surface water do not supersede the 

drinking water concentrations previously estimated (US EPA, 2002: D279732) for drinking 

water. Therefore, the values (20.68 Jlg/L for the peak (acute) concentration, 12.52 flg IL for the 

annual mean (chronic/non-cancer) concentration, and 8. 81 flg IL for the 36 year average 

concentration (chronic/cancer) from the previous drinking water assessment are recommended. 

Since requested label modifications have no implication in groundwater modeling, 

groundwater exposure for drinking water was not performed. The previous SCI-GROW model 

estimated the concentrations of parent diflubenzuron and the de gradate CPU in drinking water 

from shallow ground water sources to be 0.006 flg IL and 0.201 flg IL, respectively (US EPA, 

2002). The above concentrations can be considered as both the acute and chronic value for the 

respective chemicals. 

2 
Table of Contents 

1. Scope of Assessment 

2. Nature of the Chemical Stressor 

3. Exposure 

4. Aquatic Risk Assessment 

5. Toxicity Datafor the Parent Compound for Aquatic organisms 

6. Terrestrial Risk Assessment 

7. Toxicity Data for the Parent Compound for terrestrial organisms 

8. Listed Species Concerns 

9. Uncertainties & Data Gaps 

10. Reference 

11. Appendix A. Sample PRZMIEXAMS Output 

12. Appendix B. T-REX Outputs 

3 

3 

4 

5 

10 

10 

12 

12 

14 

14 

15 

16 

30 
1. Scope of Assessment 

The rationale to evaluate potential risks to terrestrial and aquatic organisms is to capture 

the requested modification in selected diflubenzuron product labels. The estimated drinking 

water concentrations (EDWCs) for diflubenzuron and its major degradate, 4-chlorophenyl 

urea (CPU) were also estimated for surface water, source of drinking water for human health. 

Label amendments for the product labels (Micromite 80WG(EPA Reg. No. 400-487), 

Diflubenzuron 90% Concentrate (EPA Reg. No. 400-466) and Dimilin® 2L(EPA Reg. No. 

40-461) include the following modifications: 

• Add the entire citrus crop group (Crop Group 1 0-09), which replaces oranges, 

grapefruits, tangerines and pommelos 

• Reduce retreatment intervals from 90 days to 30 days 

• Allow low volume (3 to 5 gallon per acre) with spray nozzles that produce a droplet 

size of a volume median diameter (Dv05) of2: 90j..Lm 

• An additional change in the Dimilin 2L (EPA Reg. No.400-461) label to include 

grasses/forages grown for biofuel, biomass or bioenergy production 

Proposed changes like reduced retreatment intervals and low volume application with spray 

nozzles that produce a droplet size of Dvo.s of 2: 90j..Lm may have implications on exposure 

assessment and consequently in the risk assessment. Expanding diflubenzuron use for entire 

citrus crop group and the inclusion of grasses/forages grown for biofuel, biomass/ bioenergy 

production will also cause geographic expansion of diflubenzuron uses. Table 2 includes the 

application rates of current diflubenzuron uses on citrus and grasses/forages. Since there are no 

changes in application methods and rate for grass/forages use (, revised assessment is not 

warranted for grasses/forages at this time (U.S. EPA, 2008, D346844) 

jTablel.C ...... Aftl ..... : ... feFcljBubeazunm 

Ct~~TattLabel Proposed 

LaW ~ ... ...... bte 

Propesed 

Annual 

~ 

Rate 

I Micromite 80WG, Diftubenzuron 90% Concentrate, and Dimilin® 2L 

Oranges, Citrus 

Grapefruits, Entire Crop Ground: Air 0.3125 lb a.i./acre 0.9375 lb a.i./acre Tangerines and Group Blast 

Pommelos (10-09) 

I Dimilin® 2L 

Added 

grasses/forag 

es grown for 

Aerial and Grasses/forages biofuel, Ground 0.0313 lb a.i./acre 0.0938 lb a.i./acre 

biomass or 

bioenergy 

production 

2. Nature of the Chemical Stressor 

Diflubenzuron is a benzoylphenyl urea acaricide/insecticide (insect growth regulator) 

used to control molting insect pests in agricultural and nonagricultural settings. The 

4 
physicochemical properties su~gest that diflubenzuron has a low solubility in water (0.8 mg/L). 

The vapor pressure (9.0 x 10"1 

mm Hg) and Henry's Law Constant (1.19 x 10"11 atm-m3/mol) 

indicate that diflubenzuron is a non-volatile chemical. The log Kow of3.70 suggests that 

diflubenzuron has a potential to bioaccumulate. However, diflubenzuron does appear to 

accumulate at low levels and depurate rapidly in fish tissue. The reported bioconcentration 

factors ranged from 34 to 200X for fillet, 78 to 360X for whole fish, and 100 to 500X for viscera. 

Based on registrant-submitted data, diflubenzuron appears to be relatively non-persistent 

and slightly mobile under normal use conditions. Diflubenzuron is relatively stable to hydrolysis 

and photolysis. The major route of dissipation appears to be biotic processes (half-life of 

approximately S 14 days for aerobic soil metabolism). Two major degradates, a maximum of 48 

%of 4-chlorophenylurea (CPU or p-CPU) at day 16 in a aerobic aquatic metabolism study and a 

maximum of 31% of 2,6-diflubenzoic acid (DFBA) at day 42 in anaerobic aquatic metabolism 

study were identified in the submitted environmental fate studies for diflubenzuron. However, 

there is insufficient data on the major degradates of diflubenzuron to adequately assess their 

persistence and mobility. 

Available data indicate that it is unlikely that diflubenzuron will contaminate ground 

water or appreciably volatilize and be transported through long-range atmospheric transport 

processes. However, CPU, one of the degradates of diflubenzuron has a much greater potential to 

leach through soil. Spray drift and transport with eroded soil in runoff are thought to be the main 

mechanisms of transport from the site of application. Additional information regarding the 

environmental fate and transport of diflubenzuron can be found in the previous ecological risk 

assessment to evaluate potential direct and indirect effects on the California red-legged frog 

(Rana aurora draytonii) (CRLF) (U.S. EPA, 2009; 

h_!tp://w\~Vv.cpa.gov/espp/litstatus/e!Tects/redlcg-frog/ditlubenzuron/analvsis.pdl). 

3. Exposure 

3.1. Terrestrial Exposures and Risk Assessment 

The Terrestrial Exposure (T-REX) model (Version 1.5 .1 ), an EFED computer model that uses a 

first-order dissipation relationship to account for residue dissipation between applications, was 

used to estimate exposure concentrations of diflubenzuron to terrestrial wildlife. The T -REX 

simulation model incorporates the Kenaga nomogram (Fletcher et al. 1994; Boerger and Kenaga 

1972; Pfleeger et al. 1996) (relationship between the amount of pesticide applied and the amount 

of pesticide residue present on a given food item). The model also calculates the peak 

concentration of pesticide residues on each food item on a daily interval for one year using a first 

order decay function based on the concentrations present from both the initial and additional 

applications. In addition to exposure concentrations (dose and diet-based), the I-REX model 

calculates risk quotients based on food items for mammals and birds, including herbivores, 

insectivores, and granivores. For dose-based exposures, three weight classes of mammals (15, 

35, and 1000 g) and birds (20, 100, and 1000 g) are considered. 

5 
A default foliar dissipation half-life of 35 days was used in this assessment. Example input 

parameters, such as application rate, interval, and number of applications, used in the T-REX 

model are presented with corresponding EECs in (Appendix B). 

3.2. Aquatic Exposure Assessment 

Estimated environmental concentrations (EECs) for aquatic exposures and estimated 

drinking water concentrations (EDWCs) for human health were calculated for the proposed 

changes of low volume application and retreatment intervals for diflubenzuron labels using the 

Tier II PRZM/EXAMS model with the standard pond and drinking water reservoir scenarios. 

Model description can be obtained from http://www.epa.gov/oppefed 1/modcls/watcr/#przm. 

Air-blast module of AgDRIFT (version 2.1.1) model was used in estimating spray drift fraction. 

Table 3lists the input parameters used in the PRZMIEXAMS modeling for diflubenzuron. 

Inputs and outputs of PRZM/EXAMS and AgDRIFT modeling can be found in Appendix A. 

Table 4 provides surface water EECs for aquatic exposure. 

Maximum application 0.3125 Ditlubenzuron 90% 

Rate lb a.i./ A Dimilin® 2L 

Micromite 80WG 

Number of Applications 3 Ditlubenzuron 90% 

Dimilin® 2L 

Minimum Application 

Micromite 80WG 

NA Ditlubenzuron 90% 

Intervals (days) Dimilin® 2L 

FL Citrus STD" Based on Active growing periods of citrus 

Application Date Multiple dates PRZM/EXAMS March 01, 15, 30, 

15 30 

Scenario 

Micromite 80WG For foliar application according to Depth of Incorporation 0 Ditlubenzuron 90% Input parameter guidance (USEP A, (inches) Dimilin® 2L 2009) 

Micromite 80WG 

Method of Application Ground air-blast spray Ditlubenzuron 90% 

Dimilin®2L 

Ground: 0.99 Input parameter Default values for ground spray 

Application Efficiency guidance (USEP A, 

2009) 

Spray Drift Fraction AgDRIFT Based on Air-blast with 25 ft buffer 

Air-blast: 0.0 I b modeling Estimated spray drift fractions are 

same for both pond and reservoir 

Molecular Mass (g/mol) 311 MRID 485969-0 I Product chemistry data 

Vapor Pressure (Torr) 9.0 X 10-10 MRID 485969-0 I Product chemistry data 

Henry's Law Constant 1.19 X 10- 11 Estimated EPISUITE 4.1 

(atm m3/mol) 

6 
Table 3. PRZMIEXAMS Input Panuaetersf8r,D8dw··-,,.._... • ·- ·".· 

!J;' .. ,, cOIIHaeRcs ·····:. 

Parameter Value ~ 

Solubility in Water 0,08 MRID 485969-01 Product chemistry data 

(mg/L) 

Hydrolysis tl/2 at pH 7.0 119 MRID 014355 -- (days) 

Aquatic Photolysis t 112 80 MRID 40816301 -- (days) MRID 41087802 

MRID 4172280 1 90th percentile upper confidence Aerobic Soil 4.7 MRID 46888703 bound on the mean half-life of Metabolism t 12 (days) MRID 46888708 diflubenzuron 

Aerobic Aquatic 901

h percentile upper confidence 

25.2 MRID 41837601 bound on the mean half-life of total Metabolism t12 (days) toxic residue of imazosulfuron 

Anaerobic Aquatic 102 (34 X 3)" MRID 41837601 Input parameter guidance (USEPA, 

Metabolism t 112 (days) 2009) 

Soil Partitioning MRID 00157842 Represent average Kroc from 4 soils 

3961 Coefficient (Koc; mllgoc) MRID 46895401 

• Since low volume application is restricted in California, FL Citrus STD is the only scenario available for 

PRZM/EXAMS modeling for Citrus crop group. 

b =Spray drift fraction was estimated using AgDRlFT 2.1.1 model- Tier I Air-blast scenario (citrus, aerosol to 

fine droplet) and the Guidance on Development and Use ofthe Index Reservoir in Drinking Water Exposure 

Assessments. lillJL: www.eQa.gov. OQQefed I hnodels/waterlindex reservoir dwa.html#memo 

c Due to reported half-life for a single anaerobic aquatic metabolism study, the input half-life was multiplied by 3 

according to Guidance for Selecting Input Parameters in Modeling for Environmental Fate and Transport of 

Pesticides. Version 2.1 October 22, 2009. 

FL Citrus STD 

(PRZM/EXAMS) (3 app. X 0.3125 lbs 

ai/A) 

Water 

3.2.1 Drinking Water Exposure for human Health 

0.91-1.55 0.50-0.76 0.30-0.45 

Table 5 provides EDWCs of diflubenzuron residue in surface water source for drinking 

water. Standard percent cropped areas (PCA) were used for proposed uses as estimates of the 

extent of watershed on which crops are grown. The default PCA of 1.0 was used for the 

proposed uses because diflubenzuron can be used in both agricultural and non-agricultural 

settings (USEPA 2012). These EDWCs for surface water are higher than the previously reported 

for citrus with 0.21 ).lg /L for the 1 in 10 year annual mean (chronic) concentration, and 0.09 ).lg 

7 
/L for the 3 6 year average concentration except 3. 4 7j.tg /L for the 1 in 1 0 year annual peak 

(acute) concentration (USEPA 2002, DP 279732+). Therefore, the currently calculated EDWCs 

of 3.4 7~-tg /L for the 1 in 1 0 year annual peak (acute) concentration, 0.26 j.tg /L for the 1 in 1 0 

year annual mean (chronic) concentration, and 0.12 j.tg /L for the 30 year average concentration 

are recommended. 

Estimated drinking water concentrations were also calculated for the major degradate, 4-

chlorophenyl urea (CPU) of diflubenzuron using PRZM/EXAMS model. Table 5 provides input 

values used in CPU modeling. Table 6 provides the EDWCs of CPU residue in surface water. 

Sample PRZMIEXAMS output can be found in Appendix A. The EDWCs of CPU in drinking 

water for citrus uses are lower than the previous reported values for drinking water assessment 

(US EPA 2002, DP 279732+). The reported values were 20.68 j.tg/L for the 1 in 10 year annual 

peak (acute) concentration, 12.52 j.tg /L for the 1 in 10 year annual mean (chronic/non-cancer) 

concentration, and 8. 81~-tg /L for the 36 year average concentration (chronic/cancer). Therefore, 

the current EDWCs (Table 5) for surface water do not supersede the drinking water 

concentrations previously estimated for CPU. 

Table 5. PRZMIEXAMS Input Parameters for CPU Modelin2 

Parameter Value Source Comments 

Micromite -- Maximum 80WG 

application Rate lb 0.0.641 Diflubenzuron 

a.i./ A 90% 

Dimilin® 2L 

Micromite 80WG Based on parent application Number of Applications 3 Diflubenzuron 90% 

Dimilin® 2L 

Minimum Application 

Micromite 80WG Based on parent application NA Diflubenzuron 90% 

Intervals (days) Dimilin® 2L 

FL Citrus Based on During active growth of citrus Multiple dates : PRZM/EXAMS 

Application Date 

March 01, 15,30 Scenarios Aprill5, 30 

May 15, 30 

June 15, 30 

Micromite 80WG For foliar application according to Depth of Incorporation Diflubenzuron 90% 

(inches) 0 Dimilin® 2L Input parameter guidance (USEP A, 

2009) 

Method of Application Ground application Assumed Contribution from degradation 

Application Efficiency Ground: 1.0 Assumed Contribution from degradation 

Spray Drift Fraction 0 Assumed Contribution from degradation 

Molecular Mass (g/mol) 100.6 

DP D279732+ Values from previous assessment US EPA, 2002 

Vapor Pressure (Torr) 1.65 X 10-04 DP D279732+ Values from previous assessment US EPA, 2002 

8 
Table 5. PRZMIEXAMS Input Parameters for CPU Modeling 

Parameter Value Source Comments 

Henry's Law Constant OP 0279732+ Values from previous assessment 1.49 x ro-'o US EPA, 2002 (atm m3/mol) 

Solubility in Water OP 0279732+ Values from previous assessment 

(mg/L) 1770 US EPA, 2002 

Hydrolysis tl/2 at pH 7.0 0 Assumed No data 

(days) 

Aquatic Photolysis t 112 0 Assumed No data 

(days) 

Aerobic Soil OP 0279732+ Values from previous assessment 

Metabolism t 112 (days) 11 I US EPA, 2002 

Aerobic Aquatic OP 0279732+ Twice the aerobic metabolism t 112 

Metabolism t 112 (days) 222 US EPA,2002 was used 

Anaerobic Aquatic 0 Assumed No data 

Metabolism t,;2 (days) 

Soil Partitioning DP 0279732+ Values from previous assessment 

Coefficient (Koc; m1/g0 c) 246 US EPA, 2002 

Table 6~ Raage of Estilmltfed-·!!j·f! 

for Sudaee Water 

Surface :Water 

(model) 

Diflubenzuron 

FL Citrus STO 

(3 app. X 0.3125 lbs Water 1.92-3.46 0.18-0.26 0.09-0.12 

ai/A) (PRZM/EXAMS)r-------------~--------~--------~----------~------~ 

FL Citrus STO 

(3 app. X 0.064 1bs 

ai/A) 1 

4-chlorophenyl urea (CPU) 

Water 2.11-2.69 0.80-0.87 0.60-0.64 

'= Diflubenzuron application rate (0.3125 lb/A) x [(0.37, the maximum conversion rate from the aerobic soil 

degradation of diflubenzuron to CPU in laboratory studies) x (0.55, the molecular weight ratio of CPU to 

diflubenzuron)] 

Since requested label modifications have no implication in groundwater modeling, groundwater 

exposure for drinking water was not performed. The previous SCI-GROW model estimates the 

concentrations of parent diflubenzuron and the de gradate CPU in drinking water from shallow 

ground water sources to be 0.006 f.lg /L and 0.201 f.lg /L, respectively (DP) (YS EPA, 200???). 

9 
The above concentrations should be considered as both the acute and chronic value for the 

respective chemicals. 

4. Dijlubenzuron Toxicity Data for Aquatic organisms 

A summary of the aquatic toxicity data for diflubenzuron from registrant-submitted studies is 

provided in Table 7. 

Table 7. Summary of the Endpoints from Submitted Aquatic Toxicity Studies for 

Difl.ubenzuron 

Study Type Species Toxicity Value MRID & Status 

Acute - Freshwater Rainbow trout 00056150 Fish (Oncorhynchus mykiss) 96-hr LC50: 136000 J..lg/L Acceptable 850.1075 

Acute - Freshwater Bluegill sunfish (Lepomis 00056150 Fish 96-hr LC50: 129000J..Lg/L 

850.1075 macrochirus) Acceptable 

AcuteEstuarine/Marine Sheepshead minnow 96-hr LC50: >13.0J..Lg/L 42940101 

Fish (Cyprinodon variegatus) Acceptable 

850.1075 

Chronic - Freshwater Fathead minnow NOAEC: 100.1 J..lg/L 00099755 Fish 

850.1400 (Pimephales promelas) LOAEC: >100.1 J..Lg/L Acceptable 

Acute - Freshwater Water flea (Daphnia 45252204 Invertebrate 48-hr EC50: 2.6 J..Lg/L 

850.1010 magna) Supplemental 

AcuteEstuarine/Marine Quahog clam (Mercenaria 96-hr LC50: >320 J..Lg/L 41392002 

Invertebrate mercenaria) Acceptable 

850.1025 

AcuteEstuarine/Marine Grass shrimp 96-hr LC50 : 0.64 J..lg/L 00038612 

Invertebrate (Palaemonetes pugio) Acceptable 

850.1035 

Chronic - Freshwater Water flea (Daphnia NOAEC: 0.05 J..Lg/L 00010856 Invertebrate 

850.1300 magna) LOAEC: 0.075 J..Lg/L Supplemental 

ChronicEstuarine/Marine Mysid shrimp NOAEC 0.045 J..lg/L 40197001 

invertebrate (Americamysis bahia) LOAEC 0.086 J..Lg/L Acceptable 

850.1300 

Aquatic- Non- Green algae 96-hr EC50 : 200 J..l/L 42487101 vascular Plants (Pseudokirchneriella NOAEC: 200 J..Lg/L Supplemental 850.5400 subcapitata (no effects noted) 

Aquatic - Vascular 7-day EC50: 190 J..lg/L 42940103 Plants Duckweed (Lemna gibba) NOAEC: 190 J..lg/L Acceptable 850.4400 (no effects noted) 

10 
5. Aquatic Risk Assessment 

5.1. Fish 

Potential risks to freshwater fish from the proposed label modification were evaluated 

using the acute toxicity data for a Bluegill sunfish (Lepomis macrochirus) and chronic toxicity 

data for Fathead minnow (Pimephales promelas). RQs are summarized in Table 8. None of the 

acute and chronic RQs exceeded the listed or nonlisted species LOC for requested label changes. 

Therefore, potential risks to freshwater fish are unlikely. 

A definitive LC50 and NOAEC were not established for diflubenzuron estuarine/marine 

fish. No chronic toxicity for estuarine/marine fish was submitted by the registrant. As a result, 

acute and chronic risk quotients were not calculated for estuarine/marine fish. Submitted 

freshwater fish data showed no effects. Given the mode of action, effects are not anticipated on 

estuarine/marine fish 

Table 8. Acute and Chronic Risk Quotients for Freshwater Fish for the Proposed Label 

Modifications of Ditlubenzuron 

PRZM/EXAMS Peak Acute Freshwater 60-day Chronic 

Use Scenario EEC Freshwater 

(Application Date) (JJ.g/L) Fish RQ1 EEC Fish RQ2 

(JJ.g/L) 

Citrus FL Citrus 0.91-1.55 <0.05 0.30-0.45 <1.0 (Croup Group 10-09) (Multiple Dates) 

1 Bluegill sunfish (Lepomis macrochirus) = 129,000 ppb. 2 Fathead minnow (Pimephales promelas) = 100 ppb. 

5.2. Aquatic Invertebrates 

Potential risks to freshwater invertebrate from the proposed label modification were 

evaluated using the acute and chronic toxicity data for a Water flea (Daphnia magna). RQs are 

summarized in Table 9. Both of the acute and chronic RQs exceeded the LOC for requested 

label changes. Therefore, potential risks to freshwater invertebrates are likely. 

Table 9. Acute and Chronic Risk Quotients for Freshwater Invertebrates for the for the 

Proposed Label Modifications of Ditlubenzuron 

PRZM/EXAMS Peak Acute Freshwater 21-day Chronic 

Use Scenario EEC Invertebrate EEC Freshwater 

(Application Date) (JJ.g/L) RQt (Jlg/L) Invertebrate 

RQ2 

Citrus FL Citrus 

(Croup Group I 0-09) (Multiple Dates) 

0.91-1.55 0.4-0.6* 0.50-0.76 10.0- 15.2** 

1 Water flea (Daphnia magna)= 2.6 11g/L. 2 Water flea (Daphnia magna)= 0.05 11g/L. 

*Exceeds LOC (0.05). 

**Exceeds LOC (1.0). 

11 
Potential risks to estuarine/marine invertebrate from the proposed label modification were 

evaluated using the acute toxicity data for a Grass shrimp (Palaemonetes pugio) and a chronic 

toxicity data for a Mysid shrimp (Americamysis bahia). RQs are summarized in Table 10. Both 

of the acute and chronic RQs exceeded the listed and nonlisted species LOC for requested label 

changes. Therefore, potential risks to estuarine/marine invertebrates are likely. 

Table 10. Acute and Chronic Risk Quotients for Estuarine/Marine Invertebrates for the 

for the Proposed Label Modifications of Diflubenzuron 

PRZMIEXAMS Peak Acute Freshwater 21-day Chronic 

Use Scenario EEC Invertebrate EEC Freshwater 

(Application Date) (!lg/L) RQt (!lg!L) Invertebrate 

RQ2 

Citrus FL Citrus 0.91-1.55 0.70-2.42* 0.50-0.76 11.1-16.9** (Croup Group 10-09) (Multiple Dates) 

1 Grass shrimp (Palaemonetes pugio) = 0.64 j.!g/L. 2 Mysid shrimp (Americamysis bahia) = 0.045 j.!g/L. 

*Exceeds LOC (0.05). 

**Exceeds LOC (1.0). 

Insert here the sectiOn on nsk to terrestnal organisms from before 

5.3. Aquatic Plants 

Potential risks to aquatic plants from the proposed label modification were evaluated 

using the toxicity data for a vascular plant (Lemna minor) and a non-vascular plant 

(Pseudokirchneriella subcapitata). RQs are summarized in Table 11. None of the non-listed 

vascular and non-vascular plant RQs exceeded the LOC for requested label changes. Therefore, 

potential risks to non-listed vascular and non-vascular aquatic plants are unlikely. 

Table 11. Risk Quotients for Aquatic Plants for the Proposed Label Modifications of 

Diflubenzuron 

PRZMIEXAMS Peak Non-listed Non-listed Non-vascular Use Scenario EEC Vascular Plant Plant RQ2 

(Application Date) (!lg/L) RQt 

Citrus FL Citrus 0.91-1.55 < 1 <I (Croup Group 1 0-09) (Multiple Dates) 

1 Duckweed EC50 = 190 j.!g/L. 2 Green algae EC50 = 200 j.!g/L. 

6. Terrestrial Risk Assessment 

Effects to Terrestrial Organisms 

Table 12summarizes the terrestrial toxicity data for diflubenzuron based on an evaluation of 

submitted studies. 

12 
Table 12. Summary of the Endpoints from Submitted Terrestrial Toxicity Studies for 

Diflubenzuron 

Study Type Species Toxicity Value MRID & Status 

Acute - Avian Oral Red-winged balckbird LD50: 3763mg!kg-bw/day 00060384 

850.2100 (Agelaius phoeniceus) Acceptable 

Acute -A vi an Bobwhite Quail (Colinus 00039080 Dietary LC50 : >4640 mg!kg-diet 

850.2200 virginianus) Acceptable 

Acute - Avian Mallard Duck 00038613 Dietary (Anas platyrhynchos) LC50: >4640 mg!kg-diet Acceptable 850.2200 

Chronic -Avian Bobwhite Quail (Colinus NOAEC: 500 mg/kg-diet 41668002 Reproduction 

850.2300 virginianus) LOAEC: I 000 mg/kg-diet Acceptable 

Chronic -A vi an Mallard Duck NOAEC: 500 mg!kg-diet 4168001 Reproduction 

850.2300 (Anas platyrhynchos) LOAEC: 1000 mg!kg-diet Acceptable 

Acute- Mammalian 

Oral Rat (Rattus norvegicus) LD50: >5000 mg/kg-bw 00157103 Acceptable 

870.1100 

Chronic- NOAEL: 250mg/kg-bw/day 

Mammalian Rat (Rattus norvegicus) LOAEL:2500 mg!kg-bw/day 43578301 Acceptable Reproduction (development effects decreased 

870.3800 pup weight) 

Acute - Contact Honey Bee 00099890 Toxicity NOAEL>114.8 f.!g/bee 

850.3020 (Apis mellifera) Acceptable 

Acute oral and acute Honey Bee LD50: >30 f.lg/bee 05001991 

contact (Apis mellifera) Acceptable 

Pollinator Field Honey Bee 00071816 Study NOAEL>5 lbs ai/acre 

850.3040 (Apis mellifera) acceptable 

6.1. Birds and mammals. 

No acute LOC exceedances for birds based on LD5o: 3763mg/kg-bw/day was observed 

(Appendix B). Since the LC50 for birds was non-definitive values of>4640 mg/kg-diet, and no 

treatment related mortality was observed, risk quotients were not calculated. Based on 

application rates and the results of the acute toxicity studies, acute risk concern levels would not 

be exceeded for birds. 

The LD50 for mammals was a non-definitive value of>5000 mg/kg bw and no treatment 

related mortality was observed. Therefore, acute risk quotients were not calculated and there is 

no concern of acute risk to mammals at this time. 

No chronic LOC exceedances for birds and mammals (Appendix B). 

6.2. Terrestrial plants. 

No toxicity terrestrial plant studies were submitted by the registrant. Therefore, no 

terrestrial EECs for terrestrial plant exposure were calculated for the proposed modification of 

13 
diflubenzuron labels. Submitted aquatic plant data showed no effects. Given the mode of action, 

effects are not anticipated on terrestrial plants. 

6.3. Terrestrial Invertebrates. 

EFED currently does not estimate risk quotients for terrestrial non-target insects. Based 

on the acute contact toxicity study to honeybees, the LD5o is 114.8 1-1g/bee. Thus, the toxicity 

category for the TGAI of diflubenzuron in reference to honeybees being exposed is practically 

non-toxic. 

Conversely, the 25 WP formulation of diflubenzuron is categorized as "Very Highly 

Toxic" to juvenile non-targeted terrestrial insects on an acute contact basis. The LD5o value was 

estimated to be 2 1-1g/bee. 

7. Listed Species Concerns 

Expanding diflubenzuron use for entire citrus crop group and the inclusion of 

grasses/forages grown for biofuel, biomass/ bioenergy production will cause geographic 

expansion of diflubenzuron uses. Listed species location analysis and potential risks to listed 

species that could be affected directly or indirectly by the extended use of diflubenzuron on 

citrus crop group and grasses/forages grown for biofuel, biomass/bioenergy production will be 

evaluated in the future Registration Review risk assessment for diflubenzuron. 

8. Uncertainties & Data Gaps 

Uncertainties and data gaps remain the same as those described in the previous assessment of 

diflubenzuron (U.S. EPA, 2009). 

14 
References 

U.S. EPA 2002. Environmental Fate and Ecological Effects Assessment and Characterization for 

a Section 3 for Aerial and Ground Spray Treatment to Pears, Stone Fruits, Almonds, 

Peppers, and Pasture Grass (DP Barcode D279732, D279735, D278770) Ecological Fate 

and Effects Division, Office of Pesticide Programs, U.S. Environmental Protection 

Agency, Washington D.C. May 2002. 

U.S. EPA 2006. Environmental Fate and Ecological Risk Assessment for the Registration of 

Diflubenzuron (Dimilin-2L) Use on Peanuts, Okra, Small Grains-(Winter wheat, Spring 

wheat, Durum, Barley, and Oats), Pummelo, Mustard Greens, Broccoli, Raab, Cabbage, 

Chinese (bok choy); Collards; Kale; Mizuna; Mustard spinach; Rape, Greens and Turnip 

greens. (DP 321153, DP 321278). Ecological Fate and Effects Division, Office of 

Pesticide Programs, U.S. Environmental Protection Agency, Washington D.C., 

September 2006. 

US EPA, 2008. Section 3 New Use Request Registration for the use of Diflubenzuron (Dimilin 

2LTM) on turf grass (for use in sod-farms only). (DP Barcode D346844) U. S. 

Environmental Protection Agency. Washington, D.C 

US EPA, 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport ofPesticides, Version II. U.S. Environmental Protection Agency. 

Washington, D.C. http://www.epa.gov/oppefedl/models/water/ 

US EPA, 2009. Risks ofDiflubenzuron Use to Federally Threatened California Red-legged Frog 

(Rana aurora draytonii). U.S. Environmental Protection Agency. Washington, D.C. 

http://www.epa.gov/espp/litstatus/effects/redleg-frog/ditlubenzuron/analysis.pdf 

US EPA. 2012. Development and Use of Percent Cropped Area and Percent Turf Area 

Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update 

http://v,vvw.cpa.gov/oppefcd 1 /models/water/pea adjustment dwa.html 

15 
Appendix A. 

Sample PRZM/EXAMS Output 

Dijlubenzuron Ground Application to FL Citrusfor Aquatic Exposure 

Table A-1. PRZM/EXAMS EECs (f.lg/L) Output for Multiple Dates 

DATE peak 96hr 21day 60day 90day yrly overallavg 

01-03 1.55 1.29 0.76 0.39 0.30 0.11 0.06 

15-03 1.08 0.91 0.50 0.30 0.26 0.10 0.07 

30-03 1.40 1.17 0.69 0.42 0.32 0.11 0.07 

15-04 1.10 0.92 0.51 0.37 0.30 0.11 0.07 

30-04 1.24 1.03 0.62 0.45 0.38 0.14 0.07 

15-05 1.15 0.98 0.55 0.34 0.28 0.10 0.07 

30-05 0.92 0.76 0.52 0.36 0.35 0.13 0.07 

15-06 1.29 1.07 0.65 0.35 0.28 0.11 0.07 

30-06 0.91 0.75 0.47 0.33 0.28 0.10 0.07 

Dijlubenzuron Ground Application to FL Citrus for Drinking Water 

Table A-2. PRZM/EXAMS EDWCs (f.lg/L) Output for Multiple Dates 

DATE peak 96hr 21day 60day 90day yr1y overallavg 

01-03 3.46 2.96 1.82 0.89 0.64 0.19 0.09 

15-03 2.33 2.00 1.20 0.66 0.55 0.19 0.10 

30-03 3.12 2.67 1.68 0.93 0.68 0.20 0.11 

15-04 2.29 1.98 1.14 0.82 0.62 0.19 0.12 

30-04 2.75 2.35 1.52 0.98 0.83 0.26 0.12 

15-05 2.46 2.13 1.26 0.74 0.57 0.18 0.11 

30-05 1.95 1.65 1.17 0.78 0.73 0.23 0.10 

15-06 2.91 2.48 1.50 0.77 0.60 0.20 0.11 

30-06 1.92 1.62 1.10 0.71 0.58 0.18 0.10 

CPU from Ground Application of Dijlubenzuron to FL Citrus for Drinking Water 

Table A-1. PRZM/EXAMS CPU EDWCs (f.lg/L) Output for Multiple 

Dates 

DATE peak 96hr 21day 60day 90day yrly overallavg 

01-03 2.34 2.15 1.83 1.54 1.31 0.81 0.60 

15-03 2.30 2.11 1.65 1.38 1.26 0.85 0.62 

30-03 2.34 2.19 1.70 1.46 1.35 0.87 0.63 

15-04 2.38 2.22 1.89 1.40 1.26 0.87 0.64 

30-04 2.15 2.00 1.72 1.42 1.33 0.86 0.63 

15-05 2.11 1.99 1.61 1.29 1.18 0.88 0.62 

30-05 2.20 2.03 1.74 1.37 1.26 0.84 0.61 

16 
15-06 2.39 2.21 1.89 1.39 1.28 0.82 0.61 

30-06 2.69 2.49 1.97 1.47 1.32 0.80 0.60 

Example of PRZM Output for Aquatic Exposure 

stored as FLCitrus_01-03.out 

Chemical: Diflubenzuron 

PRZM environment: FLcitrusSTD.txt, Modified: Tueday, 29 May 2007 at 12:45:56 

EXAMS environment: pond298.exv, modified Tueday, 26 August 2008 at 05:14:08 

Metfile: w12844.dvf 

modified Tueday, 26 August 2008 at 05:14:22 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.42 0.35 0.21 0.15 0.12 0.04 

1962 0.41 0.35 0.23 0.19 0.15 0.06 

1963 1.62 1.38 0.77 0.40 0.30 0.11 

1964 0.30 0.25 0.20 0.17 0.14 0.06 

1965 0.21 0.17 0.10 0.08 0.08 0.03 

1966 0.23 0.19 0.13 0.11 0.10 0.04 

1967 0.27 0.23 0.13 0.10 0.10 0.04 

1968 0.21 0.18 0.16 0.12 0.11 0.05 

1969 0.69 0.60 0.36 0.20 0.18 0.07 

1970 0.74 0.62 0.40 0.26 0.24 0.09 

1971 0.36 0.30 0.20 0.14 0.12 0.05 

1972 1.68 1.40 0.81 0.44 0.36 0.12 

1973 0.32 0.27 0.18 0.12 0.11 0.04 

1974 0.24 0.21 0.15 0.12 0.11 0.04 

1975 0.21 0.17 0.10 0.08 0.08 0.03 

1976 0.23 0.21 0.16 0.12 0.11 0.04 

1977 1.57 1.30 0.79 0.42 0.32 0.11 

1978 0.28 0.24 0.16 0.11 0.11 0.04 

1979 1.42 1.18 0.72 0.38 0.29 0.10 

1980 0.58 0.49 0.27 0.18 0.17 0.06 

1981 0.21 0.18 0.12 0.10 0.10 0.04 

1982 0.59 0.50 0.40 0.26 0.25 0.09 

1983 0.23 0.20 0.13 0.10 0.10 0.04 

1984 0.53 0.45 0.30 0.23 0.22 0.08 

1985 0.43 0.36 0.26 0.21 0.17 0.06 

1986 0.23 0.19 0.12 0.10 0.10 0.04 

1987 0.39 0.35 0.26 0.20 0.19 0.07 

1988 1.37 1.14 0.63 0.33 0.25 0.10 

1989 0.34 0.30 0.21 0.15 0.12 0.05 

1990 0.21 0.18 0.11 0.09 0.09 0.04 

17 
Sorted results 

Pro b. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.03 1.68 1.40 0.81 0.44 0.36 0.12 

0.06 1.62 1.38 0.79 0.42 0.32 0.11 

0.10 1.57 1.30 0.77 0.40 0.30 0.11 

0.13 1.42 1.18 0.72 0.38 0.29 0.10 

0.16 1.37 1.14 0.63 0.33 0.25 0.10 

0.19 0.74 0.62 0.40 0.26 0.25 0.09 

0.23 0.69 0.60 0.40 0.26 0.24 0.09 

0.26 0.59 0.50 0.36 0.23 0.22 0.08 

0.29 0.58 0.49 0.30 0.21 0.19 0.07 

0.32 0.53 0.45 0.27 0.20 0.18 0.07 

0.35 0.43 0.36 0.26 0.20 0.17 0.06 

0.39 0.42 0.35 0.26 0.19 0.17 0.06 

0.42 0.41 0.35 0.23 0.18 0.15 0.06 

0.45 0.39 0.35 0.21 0.17 0.14 0.06 

0.48 0.36 0.30 0.21 0.15 0.12 0.05 

0.52 0.34 0.30 0.20 0.15 0.12 0.05 

0.55 0.32 0.27 0.20 0.14 0.12 0.05 

0.58 0.30 0.25 0.18 0.12 0.11 0.04 

0.61 0.28 0.24 0.16 0.12 0.11 0.04 

0.65 0.27 0.23 0.16 0.12 0.11 0.04 

0.68 0.24 0.21 0.16 0.12 0.11 0.04 

0.71 0.23 0.21 0.15 0.11 0.11 0.04 

0.74 0.23 0.20 0.13 0.11 0.10 0.04 

0.77 0.23 0.19 0.13 0.10 0.10 0.04 

0.81 0.23 0.19 0.13 0.10 0.10 0.04 

0.84 0.21 0.18 0.12 0.10 0.10 0.04 

0.87 0.21 0.18 0.12 0.10 0.10 0.04 

0.90 0.21 0.18 0.11 0.09 0.09 0.04 

0.94 0.21 0.17 0.10 0.08 0.08 0.03 

0.97 0.21 0.17 0.10 0.08 0.08 0.03 

0.10 1.55 1.29 0.76 0.39 0.30 0.11 

Average 0.06 

of yearly 

averages 

Inputs generated by pe5.pl- Novemeber 2006 

Data used for this run: 

Output File: FLCitrus_01-03 

18 
Metfile: w12844.dvf 

PRZM FlcitrusSTD.txt 

scenario: 

EXAMS pond298.exv 

environ 

ment 

file: 

Chemica Diflubenzuron 

I Name: 

Descripti Variable Value Units Comments 

on Name 

Molecul mwt 311 g/mol 

ar 

weight 

Henry's henry 1.87E-09 atm-mA3/mol 

Law 

Con st. 

Vapor vapr 9.00E-10 torr 

Pressure 

Solubilit sol 0.08 mg/L 

y 

Kd Kd mg/L 

Koc Koc 3961 mg/L 

Photolys kdp 80 days Half-life 

is halflife 

Aerobic kbacw 25.2 days Halfife 

Aquatic 

Metaboli 

sm 

Anaerob kbacs 102 days Halfife 

ic 

Aquatic 

Metaboli 

sm 

Aerobic asm 5.11 days Halfife 

Soil 

Metaboli 

sm 

Hydrolys pH 7 119 days Half-life 

is: 

Method: CAM 2 integer See PRZM manual 

lncorpor DE PI em 

ation 

Depth: 

Applicati TAPP 0.35 kg/ha 

on Rate: 

19 
Applicati APPEFF 0.99 fraction 

on 

Efficienc 

y: 

Spray DRFT 0.01 fraction of application rate applied to pond 

Drift 

Applicati Date 3-Jan dd/mm or dd/mmm or dd-mm or dd-mmm 

on Date 

Interval interval 30 days Set to 0 or delete line for single app. 

1 

app. rate apprate kg/ha 

1 

Interval interval 30 days Set to 0 or delete line for single app. 

2 

app. rate apprate kg/ha 

2 

Record FILTRA 

17: 

IPSCND 1 

UPTKF 

Record PLVKRT 

18: 

PLDKRT 

FEXTRC 0.5 

Flag for IR EPA 

Index Pond 

Res. Run 

Flag for RUNOFF none none, monthly or total(average of entire run) 

runoff 

calc. 

20 
Example of PRZM Output for Drinking Water Exposure (Dijlubenzuron) 

stored as FLCitrus_DW_01-03.out 

Chemical: Diflubenzuron 

PRZM environment: FLcitrusSTD.txt,modified Tueday, 29 May 2007 at 12:45:56 

EXAMS environment: ir298.exv,modified Tueday, 26 August 2008 at 05:14:08 

Metfile: w12844.dvf, modified Tueday, 26 August 2008 at 05:14:22 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.74 0.64 0.38 0.24 0.19 0.06 

1962 0.75 0.65 0.42 0.34 0.27 0.08 

1963 3.57 3.14 1.84 0.89 0.64 0.19 

1964 0.55 0.48 0.37 0.29 0.23 0.08 

1965 0.19 0.17 0.13 0.09 0.08 0.03 

1966 0.27 0.24 0.17 0.15 0.13 0.05 

1967 0.36 0.31 0.24 0.14 0.14 0.05 

1968 0.39 0.37 0.29 0.21 0.16 0.06 

1969 1.40 1.23 0.77 0.39 0.33 0.11 

1970 1.63 1.41 0.97 0.54 0.47 0.16 

1971 0.74 0.64 0.38 0.22 0.17 0.06 

1972 3.69 3.16 1.93 1.00 0.78 0.24 

1973 0.59 0.50 0.30 0.17 0.15 0.05 

1974 0.50 0.43 0.28 0.18 0.14 0.05 

1975 0.15 0.13 0.08 0.07 0.06 0.02 

1976 0.35 0.31 0.23 0.16 0.16 0.06 

1977 3.47 2.97 1.92 0.96 0.70 0.21 

1978 0.44 0.38 0.23 0.14 0.12 0.05 

1979 3.32 2.85 1.73 0.87 0.63 0.19 

1980 1.09 0.94 0.56 0.31 0.28 0.10 

1981 0.30 0.26 0.18 0.13 0.12 0.04 

1982 1.20 1.04 0.85 0.55 0.51 0.16 

1983 0.29 0.25 0.19 0.12 0.13 0.05 

1984 1.17 1.01 0.65 0.47 0.44 0.15 

1985 0.96 0.83 0.54 0.38 0.30 0.10 

1986 0.28 0.25 0.16 0.13 0.11 0.04 

1987 0.83 0.72 0.52 0.36 0.36 0.12 

1988 2.92 2.50 1.46 0.72 0.53 0.17 

1989 0.73 0.64 0.41 0.23 0.18 0.06 

1990 0.41 0.35 0.21 0.13 0.11 0.04 

Sorted results 

Pro b. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.03 3.69 3.16 1.93 1.00 0.78 0.24 

21 
0.06 3.57 3.14 1.92 0.96 0.70 0.21 

0.10 3.47 2.97 1.84 0.89 0.64 0.19 

0.13 3.32 2.85 1.73 0.87 0.63 0.19 

0.16 2.92 2.50 1.46 0.72 0.53 0.17 

0.19 1.63 1.41 0.97 0.55 0.51 0.16 

0.23 1.40 1.23 0.85 0.54 0.47 0.16 

0.26 1.20 1.04 0.77 0.47 0.44 0.15 

0.29 1.17 1.01 0.65 0.39 0.36 0.12 

0.32 1.09 0.94 0.56 0.38 0.33 0.11 

0.35 0.96 0.83 0.54 0.36 0.30 0.10 

0.39 0.83 0.72 0.52 0.34 0.28 0.10 

0.42 0.75 0.65 0.42 0.31 0.27 0.08 

0.45 0.74 0.64 0.41 0.29 0.23 0.08 

0.48 0.74 0.64 0.38 0.24 0.19 0.06 

0.52 0.73 0.64 0.38 0.23 0.18 0.06 

0.55 0.59 0.50 0.37 0.22 0.17 0.06 

0.58 0.55 0.48 0.30 0.21 0.16 0.06 

0.61 0.50 0.43 0.29 0.18 0.16 0.06 

0.65 0.44 0.38 0.28 0.17 0.15 0.05 

0.68 0.41 0.37 0.24 0.16 0.14 0.05 

0.71 0.39 0.35 0.23 0.15 0.14 0.05 

0.74 0.36 0.31 0.23 0.14 0.13 0.05 

0.77 0.35 0.31 0.21 0.14 0.13 0.05 

0.81 0.30 0.26 0.19 0.13 0.12 0.05 

0.84 0.29 0.25 0.18 0.13 0.12 0.04 

0.87 0.28 0.25 0.17 0.13 0.11 0.04 

0.90 0.27 0.24 0.16 0.12 0.11 0.04 

0.94 0.19 0.17 0.13 0.09 0.08 0.03 

0.97 0.15 0.13 0.08 0.07 0.06 0.02 

0.10 3.46 2.96 1.82 0.89 0.64 0.19 

Average 0.09429 

of yearly 1 

averages 

Inputs generated by pe5.pl - Novemeber 2006 

Data used for this run: 

Output File: FLCitrus_DW_01-03 

Metfile: w12844.dvf 

PRZM FLcitrusSTD.txt 

scenario: 

EXAMS ir298.ex 

environ v 

22 
ment 

file: 

Chemica Diflubenzuron 

I Name: 

Descripti Variable Value Units Comments 

on Name 

Molecul mwt 311 g/mol 

ar 

weight 

Henry's henry 1.87E-09 atm-mA3/mol 

Law 

Const. 

Vapor vapr 9.00E-10 torr 

Pressure 

Solubilit sol 0.08 mg/L 

y 

Kd Kd mg/L 

Koc Koc 3961 mg/L 

Photolys kdp 80 days Half-life 

is halflife 

Aerobic kbacw 25.2 days Halfife 

Aquatic 

Metaboli 

sm 

Anaerob kbacs 102 days Hal fife 

ic 

Aquatic 

Metaboli 

sm 

Aerobic asm 5.11 days Hal fife 

Soil 

Metaboli 

sm 

Hydrolys pH 7 119 days Half-life 

is: 

Method: CAM 2 integer See PRZM manual 

lncorpor DE PI em 

ation 

Depth: 

Applicati TAPP 0.35 kg/ha 

on Rate: 

Applicati APPEFF 0.99 fraction 

on 

Efficienc 

y: 

Spray DRFT 0.01 fraction of application rate applied to pond 

Drift 

23 
Applicati Date 3-Jan dd/mm or dd/mmm or dd-mm or dd-mmm 

on Date 

Interval interval 30 days Set to 0 or delete line for single app. 

1 

app. rate apprate kg/ha 

1 

Interval interval 30 days Set to 0 or delete line for single app. 

2 

app. rate apprate kg/ha 

2 

Record FILTRA 

17: 

IPSCND 1 

UPTKF 

Record PLVKRT 

18: 

PLDKRT 

FEXTRC 0.5 

Flag for IR Reservoi 

Index r 

Res. Run 

Flag for RUNOFF total none, monthly or total(average of entire run) 

runoff 

calc. 

24 
Example of PRZM Output for Drinking Water Exposure (CPU) 

stored as CPU_DW_30-06 .out 

Chemical: CPU 

PRZM environment: FLcitrusSTD.txt,modified Tueday, 29 May 2007 at 12:45:56 

EXAMS environment: ir298.exv, modified Tueday, 26 August 2008 at 05:14:08 

Metfile: w12844.dvf, modified Tueday, 26 August 2008 at 05:14:22 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.34 0.32 0.27 0.20 0.19 0.07 

1962 1.15 1.10 0.87 0.60 0.52 0.28 

1963 2.19 2.04 1.61 1.09 0.93 0.43 

1964 2.32 2.18 1.80 1.43 1.33 0.72 

1965 2.80 2.57 2.24 1.71 1.40 0.82 

1966 1.67 1.57 1.42 1.24 1.19 0.93 

1967 1.73 1.62 1.30 1.09 0.97 0.72 

1968 2.46 2.29 1.92 1.48 1.32 0.80 

1969 1.59 1.50 1.31 1.22 1.12 0.79 

1970 0.86 0.82 0.76 0.71 0.72 0.60 

1971 1.42 1.31 1.00 0.70 0.61 0.42 

1972 1.56 1.45 1.16 0.89 0.81 0.57 

1973 1.02 0.98 0.85 0.81 0.73 0.54 

1974 1.49 1.38 1.11 0.82 0.73 0.53 

1975 2.08 1.90 1.51 1.04 0.89 0.51 

1976 1.44 1.36 1.08 0.92 0.87 0.56 

1977 2.72 2.51 1.98 1.35 1.16 0.67 

1978 1.54 1.47 1.23 0.92 0.85 0.63 

1979 2.75 2.51 2.08 1.51 1.29 0.71 

1980 1.05 0.99 0.92 0.79 0.72 0.62 

1981 1.68 1.59 1.27 1.13 1.05 0.59 

1982 1.89 1.77 1.52 1.13 1.02 0.71 

1983 1.70 1.57 1.22 1.05 0.94 0.72 

1984 1.98 1.85 1.44 1.02 0.93 0.67 

1985 1.20 1.12 0.99 0.78 0.76 0.61 

1986 1.02 0.96 0.79 0.70 0.64 0.51 

1987 1.78 1.64 1.33 1.15 1.02 0.58 

1988 2.31 2.12 1.59 1.16 1.06 0.70 

1989 0.63 0.62 0.60 0.57 0.55 0.48 

1990 1.80 1.66 1.43 1.05 0.94 0.54 

Sorted results 

Pro b. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.03 2.80 2.57 2.24 1.71 1.40 0.93 

0.06 2.75 2.51 2.08 1.51 1.33 0.82 

25 
0.10 2.72 2.51 1.98 1.48 1.32 0.80 

0.13 2.46 2.29 1.92 1.43 1.29 0.79 

0.16 2.32 2.18 1.80 1.35 1.19 0.72 

0.19 2.31 2.12 1.61 1.24 1.16 0.72 

0.23 2.19 2.04 1.59 1.22 1.12 0.72 

0.26 2.08 1.90 1.52 1.16 1.06 0.71 

0.29 1.98 1.85 1.51 1.15 1.05 0.71 

0.32 1.89 1.77 1.44 1.13 1.02 0.70 

0.35 1.80 1.66 1.43 1.13 1.02 0.67 

0.39 1.78 1.64 1.42 1.09 0.97 0.67 

0.42 1.73 1.62 1.33 1.09 0.94 0.63 

0.45 1.70 1.59 1.31 1.05 0.94 0.62 

0.48 1.68 1.57 1.30 1.05 0.93 0.61 

0.52 1.67 1.57 1.27 1.04 0.93 0.60 

0.55 1.59 1.50 1.23 1.02 0.89 0.59 

0.58 1.56 1.47 1.22 0.92 0.87 0.58 

0.61 1.54 1.45 1.16 0.92 0.85 0.57 

0.65 1.49 1.38 1.11 0.89 0.81 0.56 

0.68 1.44 1.36 1.08 0.82 0.76 0.54 

0.71 1.42 1.31 1.00 0.81 0.73 0.54 

0.74 1.20 1.12 0.99 0.79 0.73 0.53 

0.77 1.15 1.10 0.92 0.78 0.72 0.51 

0.81 1.05 0.99 0.87 0.71 0.72 0.51 

0.84 1.02 0.98 0.85 0.70 0.64 0.48 

0.87 1.02 0.96 0.79 0.70 0.61 0.43 

0.90 0.86 0.82 0.76 0.60 0.55 0.42 

0.94 0.63 0.62 0.60 0.57 0.52 0.28 

0.97 0.34 0.32 0.27 0.20 0.19 0.07 

0.10 2.69 2.49 1.97 1.47 1.32 0.80 

Average 0.60 

of yearly 

averages 

Inputs generated by pe5.pl- Novemeber 2006 

Data used for this run: 

Output File: CPU_DW_30-06 

Metfile: w12844.dvf 

PRZM FLcitrusSTD.txt 

scenario: 

EXAMS ir298.ex 

environ v 

ment 

26 
file: 

Chemica CPU 

I Name: 

Descripti Variable Value Units Comments 

on Name 

Molecul mwt 170.6 g/mol 

ar 

weight 

Henry's henry 1.49E-10 atm-m"3/mol 

Law 

Con st. 

Vapor vapr 1.65E-04 torr 

Pressure 

Solubilit sol 1770 mg/L 

y 

Kd Kd mg/L 

Koc Koc 3961 mg/L 

Photolys kdp 0 days Half-life 

is halflife 

Aerobic kbacw 222 days Halfife 

Aquatic 

Metaboli 

sm 

Anaerob kbacs days Halfife 

ic 

Aquatic 

Metaboli 

sm 

Aerobic asm 111 days Halfife 

Soil 

Metaboli 

sm 

Hydrolys pH 7 0 days Half-life 

is: 

Method: CAM 2 integer See PRZM manual 

lncorpor DE PI em 

at ion 

Depth: 

Applicati TAPP 0.072 kg/ha 

on Rate: 

Applicati APPEFF 1 fraction 

on 

Efficienc 

y: 

Spray DRFT 0 fraction of application rate applied to pond 

Drift 

27 
Applicati Date 30-06 dd/mm or dd/mmm or dd-mm or dd-mmm 

on Date 

Interval interval 30 days Set to 0 or delete line for single app. 

1 

app. rate apprate kg/ha 

1 

Interval interval 30 days Set to 0 or delete line for single app. 

2 

app. rate apprate kg/ha 

2 

Record FILTRA 

17: 

IPSCND 1 

UPTKF 

Record PLVKRT 

18: 

PLDKRT 

FEXTRC 0.5 

Flag for IR Reservoi 

Index r 

Res. Run 

Flag for RUNOFF total none, monthly or total(average of entire run) 

runoff 

calc. 

28 
Input and Output of AgDRIFT Modeling 

Title 

Untitled 

Combination Orchards 

r Normal (Stone and Pome Fruit Vineyard) 

r. Qense (Citrus, Tall Trees) 

r ,S_parse [Young, Dormant) 

r Y:ineyard 

r

4 .Qrchard 

Information 

Dense (Citrus, Tall Trees) 

This composite orchard combines Almond, 

Orange, Grapefruit Small Grapefruit (mist 

blower). and Pecan orch11rds. 

Mean deposition 

Application Efficiency(%) (20 rows): 98.01 

E ~tended Settings 

I 8ccess E~tended Settings 

r 

r 

r 

r 

r 

r 

r 

r 

r 

r 

r 

' Aquatic Assessment 15<1 

Aquatic Body Definition 

r. EPA-Defined Pond 

r EPA-DefinedWetland 

r User-defined Water Body 

Downwind Water Body Width: 1208.7 ft 

Average Depth: 16.56 ft 

Tier I Settings 

Active Rate: lo.3125 lb/ac 

Calculations 

Distance To Water Body From l25 Edge of Application Area: 

Initial Average 

Deposition: 

Initial Average 

Concentration: 

looo74 

1130.4 

ft 

Fraction of Applied 

g/ha l00023 

ng/l (ppt) 

lb/ac 

_j _j Erl.nt jjr, .... r.::.i'c ...... ,,l ..... !!!.~ ....... ; CIOSi! 

29 
Appendix B. Avian and Mammalian Risk Quotient Calculations for Diflubenzuron 

Based on T-REX 

Upper Bound Kenaga Residues For RQ Calculation 

Chemical Name: Diflubenzuron 

Use 0 

Fotttlulatlon 0 

APillitt~tlon ~btl! 0.3215 lbs a. i./acre 

H11lf-llfu 3S days 

APillitiltiOh lhtllf\1111 30 days 

M~Mimmtlll Apps.!Year 3 

Length of Slmul11tlon 1 year 

V~:~rll!ble IIPPIItatlon rates? no 

endpoints 

Red-wing blackbird LD50 (mg/kg-bw) 

Bobwhite quail LC50 (mg/kg-diet) 

Avian Mallard duck NOAEL(mg/kg-bw) 

Bobwhite quail NOAEC (mg/kg-diet) 

LD50 (mg/kg-bw) 

Mammals LC50 (mg/kg-diet) 

NOAEL (mg/kg-bw) 

NOAEC lmu/ku-diet 

Dietary-baaed EECs (ppm) Kenaga 

Values 

Short Gtllss 143.27 

Tllll Gtass 65.67 

Elto:H!dle~f plahts 80.59 

Ftlllt&fpl:ld&iseeds 6.95 

Arthropods 56.11 

30 

3763.00 

0.00 

o.oo 

500.00 

0.00 

0.00 

250.00 

5000.00 

Acute and Chrome ROs are l:laseel on tne Upp 

Kenaga Residues 

The maximum smgle day res1due est1 rnanon 1S 

both the acute and reproduct1on ROs 

RQs reported as "0.00" in the RQ t 

<0.01 in your assessment. This is 

figure issues in Excel. 

Que1tlon1? 

Commentl? 

Click here 

ables bE 

due tor 
Avian Results 

Dose-baaed EECs 

(mgikg>bw) 

Short Gnus 

Tall Grass 

Elroadl<!al plat1ts 

FtltitsiiHlils 

Arthropods 

S<!<!ds 

Dose-based RQs 

(bbn·band EEC/adjuated L060) 

ISMrt Gr!lss 

Tall Gr!lss 

Elrol!ill<!tlf plt~nts 

Ftltitslpoils 

Arthropods 

S~<!ds 

Dietary-based RQs 

Short Grass 

Tall Grass 

aroadleaf plants 

FruitsltJodslseads 

Arthropods 

Avian 

Cle• 

Small 

Mid 

Large 

Granivores 

20 

100 

1000 

Adjusted lD50 

3254.92 

4143.68 

5853.11 

Avian Cllll$8$ end Body Weiahtll 

smell mid 

20 100 

163.11 93.05 

74.79 42.65 

91.78 52.34 

10.20 5.82 

63.91 36.44 

2.27 1.29 

Avian Acute RQs 

Size Class (grams) 

20 100 

0.05 0.02 

0.02 0.01 

0.03 0.01 

0.00 0.00 

0.02 0.01 

0.00 0.00 

RQs 

Acute Chronic 

#DIVIO! 0.29 

#DIVIO! 0.13 

#DIVIO! 0.16 

#DIV/0! 0.02 

#DIVIO: 0.11 

t·Jtt~ Tt ptO<Id<l rl~k management Mh the maxtmum eOssible Information 

1t ~~ t€ttJinm~nd~d that both the dose-based and concentratiCn-based 

RC~ 1:~ teltulehod ·.';h~n data are acatlable 

31 

loremsl 

large 

1000 

41.66 

19.09 

23.43 

2.60 

16.32 

0.58 

1000 

0.01 

0.00 

0.00 

0.00 

0.00 

0.00 

Ingestion (Fwetl % body wgt 

consumed 

114 

65 

29 

25 

14 

6 

2.28E.02 

6.49E.02 

2.91E-01 

5.Q6E.03 

1.441:.02 

6.46E.02 
r------------------------------------~---~----~-------~-----

t:llllubl!hzlltoh u 

Mammalian Results 

Mammalian Body Ingestion (FdiYl lnge~~;.~~wet) Cless Weiaht ia bwt/devl 

15 3 14 

Herbivores/ 35 5 23 

insectivores 1000 31 153 

15 3 3 

Grainvores 35 5 5 

1000 31 34 

Mammalian Body Adjusted Adjusted 

Cless Welaht LD50 NOAEL 

15 0.00 549.46 

Herbivores/ 35 0.00 444.57 

insectivores 1000 0.00 192.29 

15 0.00 549.46 

Granivores 35 0.00 444.57 

1000 0.00 192.29 

Dose-Based EECs 

Memmellen Cl•-• end Body weight 

rams 

ort Gnus 

Ti!ll Gtilss 

ElttH!ttll!llf plllhts 

Ftllltslpotls 

Arthropods 

Sl!l!tls 

Dose-based RQs 

Dose-based EEC/LD50 or 

ort Gress 

Tall Grass 

Broadleaf plants 

Fruits/pods 

Arthropods 

Seeds 

15 

136.60 

62.61 

76.84 

8.54 

53.50 

1.90 

Smell mammal 

15 rams 

Acute 

#DIV/0! 

#DIV/0! 

#DIV/0! 

#DIV/0! 

#DIV/0! 

#DIV/0! 

35 

94.41 

43.27 

53.10 

5.90 

36.98 

1.31 

Dietary-based RQs 

(Dietary-based EEC/LC50 or 

NOAEC Acute Chronic 

Short Gtllss 

Tllll Grass 

Btolltlll!llf plants 

Ftuitslpotlslsl!l!tls 

Arthto otls 

#DIV/0! 

#DIV/0! 

#DIV/0! 

#DIV/0! 

#DIV/0! 

Not~ To pro\·ld~ risk hlShS9~hl~nt With th~ max1mum possible information 

ills rettlhlhl~nded thst both th~ dose·bssed snd concentration·based 

R09 be tsltuleted when dsts sre svsilsble 

0.03 

0.01 

0.02 

0.00 

0.01 

32 

1000 

21.89 

10.03 

12.31 

1.37 

8.57 

0.30 

Medium mammal 

35 

% bodywgt 

CO Mil mild 

95 

66 

15 

21 

15 

3 

#OIVIO! 

#OIVIO! 

#OIVIO! 

#DIViO! 

#OIVIO! 

IIOIVIO! 

Fl 

fko..fllttfiii•YI 

1.43L02 

2.3110-02 

·1.5310.01 

3.1810-03 

5 1310.03 

3.4oi0.02