UNITED STATES ENVlRONMENTAL PROTECTION AGENCY 

### WA S HINGTON D.C ., 20460

OFF I CE OF C H EM I CAL SAFETY AND POLLUTION PREVENT I ON 

### PC Code: 036501 DP Barcode: 409560 Date: May 1 , 2013 

### MEMORANDUM SUBJECT: Drinking Water Assessment for the Registration Review of Coumaphos 

### TO:



### FROM: Wilhelmena Livingston, Chemical Review Manager, Risk Management and Implementation Branch IV Pesticide Re-e valuation Division (7508P !, '\ {**~** 

# T 

# /I j 

# 1 J, Faruque Khan, Ph.D. , Senior

### Scienti**~** Environmental Risk Branch I Environmental Fate and E ffects Division
BY: Ed Odenkirchen, Ph.D., Acting Branch hief

# ~**~** APPROVED**~** Sujatha Sankula, Ph.D., Lead

# Biologist~**~- ;~** **~~~ ~**  \\\\.3 Environmental Risk Branch I (7507P) \

- Environmental Fate and Effects Division This memorandum provides the estimated drinking water concentrations (EDWC) of coumaphos and its oxygen analog coumaphoxon in surface water and groundwater in support ofhuman health risk assessment. Coumaphos (0-[3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7 -yl] 0,0- diethyl phosphorothioate) is an organophosphate insecticide/acaricide. Currently, coumaphos is registered for the control of insects, mites, and ticks on livestock and swine bedding, and to control varroa mites and small hive beetles in bee hives. However, the Environmental Fate and Effects Division (EFED) believes that the disposal ofbioremidiated coumaphos dip vat solution on non-agricultural land wou ld be a major exposure route to drinking water sources for human consumptions. Therefore , the coumaphos application rate used in the drinking water assessment is based on the proposed disposal of bioremediated coumaphos dip vat solution on nonagricultural lands (US EPA, 1998). The recommended application rate for coumaphos spent solution from dip vat operations on non- agricult ural land is 10,000 liters of coumaphos spent solution containing 10 ppb spread over a one-acre field. The estimated application rate of coumaphos is 0.22 lbs/Acre based on above recommendation. The residues of concern (ROC) for human health risk assessment and for tolerance expression are coumaphos and it s oxy gen analog coumaphoxon (US EPA , 2007). A maximum convers ion efficiency of coumaphos to coumaphoxon of 10.2% was derived from available data on 

### 1photodegradation in water . This conversion efficiency was used to estimate a coumaphoxon application rate of 0.022 lbs ai/ A for drinking water modeling. The EDWCs of coumaphos and coumaphoxon were generated using Tier I FIRST (fQP A Index Reservoir .S.creening Iool) model for surface water and Tier I SC IGROW (Screening Concentration in Ground Water Program). Pesticide Root Zone Model-Ground Water model (PRZM-GW) was a l so used for ground water based on recent EFED recommendation (US EPA, 2012a). The recommended EDWCs for s u rface water and groundwater are listed in 

### Tab le 1. FIRST model predicted total coumaphos residue concentration (couma phos 

### + coumaphoxon) in surface water are not li kely to exceed 5.20 1-1g/L coumaphos equivalent/L for the maximum peak concentration (acute) and 0.72 Jlg coumaphos equivalent/L for the average concentration (chronic). SCI

- GROW and PRZM

_ GW modeling predicted total coumaphos residue concentration in groundwater used as drinking water is not likely to exceed 2.19 Jlg coumaphos equivalent/L for the maximum peak concentration (acute) and 0.96Jlg coumaphos equivalent/L for the average concentration (chronic). The recommended acute surface water concentration of 5.20 Jlg coumaphos equivalent/Lis higher than the previously recommended acute concentration of 1.86 1-1g coumaphos equivalent/L but chronic concentration of0.72Jlg coumaphos equivalent/Lis lower than the previously recommended 1.22 Jlg coumaphos equivalent/L for this chemical (US EPA, 2000a). However, GENEEC (GENeric Es timated Environmental Concentration) model was used in the previous assessment to estimate concentrations in surface water, which is not a suitable model for drinking water assessment. Recommended PRZM_ GW estimated coumaphos equivalent concentrations are higher than previously recommended concentrations for groundwater. As a screening too l , SCI GROW provides reasonable estimates of pesticide in groundwater but it does not have the capability like PRZM

- GW to consider variabi lity in leaching pot entia l of various soils, weather (including rainfall), cumulative yearly applications or depth to aquifer. In addition, PRZM-GW modeling was al so performed w ith the estimated DT50 of2761 days based on NAFT A Kinet ic modeling procedure (US EPA , 20 12b) and yielded maximum concentrat i ons of 11.1 Jlg/L and 4.43 Jlg/L for acute and chronic values respectively for groundwater using ex tended (1 00 yrs) weather data. These concentrations are approximately two to three orders of magnitude higher than the estimated acute (0
.06 Jlg/L) and chronic (0.005 Jlg/L) concentrations using 30 year weather data. In addition, there is an uncertainty re l ated to the estimated DTs o value, which is approximately 7X higher than duration of aerobic soil metabolism study and 15 to 23X higher than the reported field diss ipation half-lives. Therefore, recommended groundwater concentrations based on 3X of duration of aerob i c soil metabolism study provide reasonable concentrations in groundwater. 

### Table 1. 

### Recommended EDWCs for Drinking Water risk assessment for Coumaphos and Coumaphoxon Source of Drinking Estimated Drinking Water concentration (J.Lg/L) 

### Water Acute 

# I Chronic Coumaphos Surface Water• 4
. 80 

### I 0
.70 2

### Table 1. 

### Recommended EDWCs for Drinking Water risk assessment for Coumaphos and Coumaphoxon Source ofDrinking Estimated Drinking Water concentration (J.lg/ L) 

### Water Acute Chronic Groun d water 2.19 0
.96 Coumap hoxon Surface Water 0.40 0
.0 2 Groundwater 5.72E-05 5.72E-05 Couma phos E quivalents (Coumaphos+Coumaphoxon) Surface Water 5
.20 0
. 72 Groundwater 2.19 0.96 1 E DWC s based on Tier I FIRS T model 2 EDWCs based on PRZM-GW model 3 EDWCs based on SC I GROW Mod el 

### Modeling Approach and Input Parameters The current supported uses for coumaphos include direct application to animals , including dairy cattle, beef cattle, swine and bedding , and horses , for the control arthropod p ests including ticks , sca bie s mites, lice , flies , fleece worms and screw worms. Coumaphos can be applied by dip vats, aerosol can, dustbags , hand-held dusters , hand-he ld sprayers , backrubber o il er , mechanical du sters , shaker can, and squeeze applicator
. Based on the above understanding of the uses and methods of application on animals, there is a potential for indirect exposure of coumaphos in the environment via di slodg in g of applied c h emical from animal hide s. H owever, co um aphos is used as a primary tool as dip vat treatment in the USDA Cattle Fever Tick Eradication Program to prevent the reintroduc tion of equine and bovine piroplasmosi s into the United States (US EPA 2000b). A total vo lume of the spen t d i p vat waste generated annually in the U
. S. is estimated to be between 400 ,000 to 500 , 000 Liters (Mu lbry et a l. , 1994 and 1998). Coumaphos is also used in impregnated plastic strip s in bee hives to control varroa mites and small hive beetle s in bee hive s. For u se in bee hives , coumaphos is impregnated on a solid su bs trate which is placed ins ide the co mmercial beehive structure. Once in the beehive, the material is sheltere d from the e lements so that no runoff of coumaphos to surroundin g environments wou ld likely occur even durin g precipitation events. Therefore, EFED believes that the di spo sal of treated coumapho s dip vat so lu tion on non agricultural land wo uld be a major expo sure route for drinking water sources . A limited environmental fate database for c oumapho s indica tes that it is a persistent (DTso of > 1 year in aerobic soil) chemical and s li ghtly mobile to hardly mobile (K oc= 1874 to 10297 L/kg) in soil according to FAO classification of mobility in so il (FAO, 2000). The major pathway of co umaphos degradation appears to be photodegradation in water (DTso of 33 hours). A major degradate, oxygen analog, coumaphoxon, was detected in an aqueous photodegradation study at a maximum of 10.2% of app li ed c hemical. Limited environmenta l fate data are available for couma pho xon , which suggests that it is not a persistent compound in the terrestrial environment (DT so of0.49 to 2.27 days) and mobile t o moderately mobile**(K~=767** to 58 10 L/kg) in so il according to FAO classificat i on of mob ility i n soil (F AO, 2000). Since the environmental fate

3

### data suggest that the fate behavior of coumaphos and coumaphoxon differ in the environment, EDWCs were estimated independently for these chemicals. Residue of Concern 

### The ROC for human health risk assessment and for to lerance expression are coumaphos and its oxygen analog coumaphoxon (US EPA, 2007). ModelsSurface Water 

### Tier 1 

### EDWCs for surface water were generated using FI RST (v.1.1.0) model, dated August 5, 2007. FIRST is a screening model to estimate the concentrations found in drinking water from surface water sources for use in human health risk assessment. As such, it provides upper bound values on the concentrations that might be found in drinking water due to the use of a pesticide. FIRST model also uses a Percent Cropped Area (PCA) factor to adjust for the area within the watershed that is p lanted to the modeled crop. The national default for non - agricultural use (PCA of 1.0) was applied in this assessment according t o the current PCA guidance (US EPA 2012c).Ground water 

### Screening Concentration in Ground Water (SCI-GROW v2.3, Ju l. 29, 2003) is a regression model used as a screening too l to estimate pesticide concentrations found in ground water used as drinking water. The SCI

- GROW model and user's manual may also be downloaded from the EPA Water Models web-page (http: //www.epa.gov/oppefed1 /models/water /#sc igrow)
. PCAs are not used with the SCI

- GROW model. In addition, Tier 1 groundwater EDWCs for coumaphos and coumaphoxon, resulting from use as land farming were al so derived using the PRZM-GW model (Pesticide Root Zone Model for Groundwater, version 1. 0, August 31, 20 1 2), with the GW-GUI (Graphical User I nterface, version 1.0, August 31, 2012). PRZM-GW is a one-dimensional , finite

- difference mode l that estimates the concentrations ofpesticides in groundwater. It accounts for pesticide fate in the crop root zone by simulating pesticide transport and degradation through the soil profile after a pesticide is app lied to an agricultural field. PRZM-GW permits the assessment of multiple years of pesticide application (up to 100 years) on a single site. Six standard scenarios, each representing a different region known to be vulnerable to groundwater contaminat ions, are available for use with PRZM-GW for risk assessment purposes. In PRZM

- GW simulations, each of these standard scenarios was used. PRZM-GW output values represent pesticide concentrations in a vulnerable groundwater supp ly that is located directly beneath a rural agricultural field following many years ofpesticide appl ication. Descriptions of all executable versions of current models used in drinking water exposure can be obtained from URL link (http: //www
.epa. gov/oppefedl /models/waterQ
.

4

### Input Parameters 

### A swnmary of the model input parameter values used in FIRST, SCI-GROW , and the PRZM
_GW Models are in 

### Table 2, Table 3, and Table 4 respectively. Input parameters were selected in accordance with EFED ' s "Guidance for Selecting Input Parametet;s in Modeling the Environmental Fate and Transport of Pesticid es," Version 2.1 (USEPA, 2009). Sample model output files are located in 

### Appendix A.

Table 2. FIRST (V. 

### 1.1.0) input parameten for Coumaphos and Coumaphoxon Parameter Value Data Source Com ments 

### Coumaphos Maximum application Estimated application rate based on Rate lb a. i.J A (kg 0
.22 (0.25) Estimated 10,000 L of solution containing 10 a.i./ha) Jlg coumaphos/ ml is spread over an acre field. Number of Applications I US EPA, 1998


## --- Depth of Incorporation 0 US EPA, 1998 

## --- (inches) Method of Application Ground spray US EPA, 1998 

## --- Spray Drift 0 US EPA 1998 Applied as slurry Solubility in Water 0.2 US EPA 1994 

## --- (mg/L) Hydrolysis t 112 at pH 7.0 0 NA" Considered stable to hydrolysis @ (days) pH7.0 Aquatic Photolysis t1 12 1.38 MRID 42764101 Coumaphoxon is a major (days) MRID 43103901 degradatre (I 0.2%) Aerobic Soil 0 MRID 4051870 I Metabolism t 112 (d)

Aerobic Aquatic 0 Input parameter guidance (USEP A, Metabolism t 1 12 (d) 2009) Soil Partitioning 5904 MRID4572140I Represent average Ktoc from 4 soils Coefficient (l<oc ; mll&,c) Wetted in ? No 

## --- Assumed Percent Crop Area US EPA 2012c Recommended PCA for non 1.0 agricultural uses (Decimal) 

### Coumaphoxon Maximum application Based on application rate of

Rate lb a.i ./ A (kg 0.022 (0.025) Estimatedb coumaphos application on nona.i.lha) agricultural lands.


### 5

### Table 2. FIRST 

### (V.l.l.O) input parameters for Coumaphos and Coumaphoxon Parameter Value Data Source Comments Number of Applicat i ons I US E PA , 1998 Based on application rate of coumaphos for land farming Depth of Incorpora t ion 0 US EPA, 1998 (inches) Method o f Application Not applicable 

### --· - Degradation product of coumaphos

Solubility in Water 31.6 EPISUITE 4
. 1 Est imated value (mg/L) Hydrolysis t 112 at pH 7
.0 0 Not avai lable Assumed stabl e (days) Aquatic Photolysis t 112 0 Not avai lable Assumed stable (days) Aerob ic Soi l 90th percenti le upper confidence Metabolism DT50 (d) 4.1 MRID 4870550 1 bound on th e mean half- lif e of coumaphooxon A erobic A quatic 8.2 c 

### --- 2X ofAerobic Soil Metabolism Metabol ism t 1 n (d) DT so (days) Percent Crop Area 1.0 US EPA 20 1 2c Recommended PCA for non (Decimal) agricultural uses a Not available b Coumaphos appl ica tion rate (0 .22lb a .i/ A) x [(0.102, the maximum conversion rate from aquatic photo lytic degradation of coumaphos to coumaphoxon in laboratory studies) x (0.96, the mol ecular weight ratio of coumaphos to coumaphoxon)]

c In absence of aerobic aquatic metabol ism study, 2X o f aerobic soil metabolism DT50 value was multiplied by 2 accordin g to Guidance for selecting input parameters in modeling for environmental fate and transport of pesticides
. Version 2.1 Octob er 22, 2009
.


### Table 4. SCI-GROW (v2.3) Input Parameter Values for Coumaphos and Coumaphoxon Parameter Value Data Source Comments 

### Coumaphos Estimated application rate based on Appl ication Rate (lbs 0.22 Estimated 10,000 L of so lutio n containing 10 flg a. i./acre) coumaphos/ml is spread over an acre fie ld. Number of 1 US EPA , 1998 See Table 2 applications Since there is a threefold d iff erence in Kcoc (mL!g) 1870 MRID 45721401 observed values , lowest non-sand Koc value used. Aerob ic soil MRID 45118631 metabolism DT so 0 Stable (days) 

### Coumaphoxon 

### 6Table 4. SCI-GROW (v2.3) Input Parameter Values for Coumaphos and Coumaphoxon Parameter Value Data So ur ce Comments Application Rate (lbs 0
.02 2 (0
.025) Table2 

# --- a. i./acre) Number of Table2 app lications 

# ---**~(mUg)** 2922 MRlD 45721401 Median value Aerobic soil 4
. 1 MRID 48705501 90111 percentile upper confidence bound metabolism (DT 50) d on the mean half -l ife ofcoumaphoxon
Table 4. PRZM-GW (vl.O) Input Parameter Values for Coumaphos and Coumaphoxon Data Source Comments Parameters Va lu e Application Method Ground Table 2 

## --- Appl ication Rate 0.22 (0.25] (lbs. a .i ./ acre) [kglha] Table2 

## --- Application 1 Table2 

## --- Frequency Hydrolysis (DT50) d S tab le 

## - -- No study Aerobic soil 1095 1 MRlD 45118631 Stable. Assumed 3X of duration of metabolism (DT50) d study

Kr

oe 2922 L!Kg MRID 46808411 Average Kroe b

1 Model requires a numerica l value other than 0. DT50 was estima ted using the NAFTA degradation kinetics procedure and did not have a recommendation for modeling (Fig ure 1 , Appendix B). In addition, the estimated Single First Order (SFO) DT 50 of2761 days is well beyond the duration of study. 2 EFED input parameter guidance: httD ://www.eoa.eov / oooefed1 / model s/ water / orzrn ew/wott orzm aw inout guidance
. htm Results Estimated coumapho s concentrations in surface water and ground water u sed for drinking water are summarized 

### in Table 5 and 6. Outputs from the model runs are provided in Appendix A. FIRST model concent ration s**(~giL)** represent untreated s urface water concentrations. The SCIGR9W and PRZM-GW conce ntrations represent groundwater concentration t h at mi ght be expected in shallow unco nfined aquifers under sandy soi ls. All scenarios run in PRZM-GW required the use o f an extended weather fi le, whi ch allows the user to run the s imul ation for up to 100 years in order to observe breakthrough.

7The simulated concentrat ion s provided in this assessment are conservative estimates of concentrations in 

### drinking water. If dietary risks requ ire refinement, higher-tiered , crop-specific and location-specific models and modeling scenarios can be used.

Table 5. EDWCs for Coumaphos and Coumaphoxon Based on Bioremediated Coumaphos on Non-agriculture Land Peak (Acute) Annual Mean Drinking Water Source Crop Scenario Exposure (Chronic) (Jtg/L) Exposure (Jtg/L) Coumaphos Surface Water Generic Scenario 1 4.80 0.70 Ground water NC Cotton Scenario• 2.19 0.96 Generic**Scenario~** 3
.22E-02 3.22E-02 Coumaphoxon Surface Water Generic Scenario 4.04 0.019 Ground water FL Citrus Scenario• 8.75E-11 5.7E-11 Generic Scenario' 5.72E-05 5.72 E-05 1 EDWCs generated using FIRST model 2 EDWCs generated using PRZM-GW model 3 EDWCs generated using SCIGROWmodel Table 6. PRZM-GW results based on Based on Bioremediated Coumaphos on Nonagriculture Application Rate and Highest Pos t Average Simulation Scenario 1 Daily Breakthrough Breakthrough Time Frequency Value**(~IVL )**  Avera2e**~IVL)** (days) 0.22 lbs a.i ./ A x FL citrus 6.15E-02 1.59E-02 Incomplete 1 applications Coumaphos FL Citrus 0.37 0.08 Incomp lete FL potato 4.21E-04 6
. 56E-05 Incomplete GA peanut 3.54E05 2 .27 E-06 Incomplete NC cotton 2.19 0.96 Incomplete Delmarva sweet com 0.43 0.06 Incomplete WI com 0.05 0.004 Incomplete Couma**~hoxon** 0.22 lbs a.i./A x FL Citrus 8.75E-ll 5.70E-ll 24189 1 applications FL potato 0 0 Incomplete GA peanut 1.21El3 1.83E-14 Incomplete NC cotton 2
. 75E13 1.12E13 19073 Delmarva sweet com 7
.22E

- 15 2.69E-15 24124 WI com 3.07E-ll 8.85E-12 30881 1 These scenarios are regional vulnerable sites for groundwater evaluation. Monitoring Data 

### There were no national- sca le monitoring data available for this assessment.



### 8

### Drinking Water Treatment 

### There is no available information on the drinking water treatment effects on coumaphos and coumaphoxon.
Uncertainties 

### The main uncertainty associated with this Tier 1 drinking water assessment is the lack of acceptable environmental fate data for coumaphos and its degradate coumaphoxon. Limited data available for coumaphos and it 's degradate , coumaphoxon. Other uncertainties associated with this assessment are the application rate of coumaphos and coumaphoxon and the lack of information on the concentration of degradation products in the bioremediated coumaphos so lutions. Based on EFED guidance on proposed USDA land farming methods (US EPA, 1998) , coumaphos should be applied at a maximum application rate of0.22lbs ai/A. This application rate assumes that 10 , 000 L of solution containing 10 J.lg coumaphos / ml i s spread over an acre field. Supplemental photodegradation in water data (MRID 42764101 and 42764102) indicate that the maximum coumaphoxon concentration at any sampling time was 10.2 % of coumaphos application rate. This conversion rate was used to estimate a coumaphoxon application rate of 0.022 lbs ai/A. In addition, there is an additional uncertainty related to the estimated DTso value , which i s approximately 7X higher than duration of aerobic soil metabo l ism study and 15 to 23X higher than the reported field dissipation half-lives. Groundwater concentrations was based on 3X of duration of aerobic soil metabolism study.



### 9

### References FAO 2000. Appendix 2. Parameters ofpesticides that influence processes in the soil. In FAO Information Division Editorial Group (Ed.), Pesticide Disposal Series 8. Assessing Soil Contamination. A reference Manual, Rome: Food andAgricultural Organization of the United Nations. Available at http: //www.fao.org/DOCREP /003/X2570E/X2570E06.htm (Accessed Ap ril 10, 2013). Mulbry, W., E. Ahren, and J
. Karns. 1998. Use of a field-scale biofilter for the degradation of the organophosphate insecticide coumaphos in cattle dip wastes. Pestic. Sci. 52: 268-274. Mulbry, W., P.L. Del Valle, E. Ahren, 1996. Biodegrada tion ofthe organophosphate insecticide coumaphos in in highly contaminated soils and liquids waste. Pestic. Sci. 149 -155. US EPA. 2012a. Memorandum: Approval ofPRZM-GW for use ofDrinking Water Exposure Assessment. Environmental Fate and Effects Division, Office of Chemica l Sa f ety and Pollution Prevention. U.S. E nvironmental Protection Agency. US EPA. 2012a. Memorandum: NAFTA Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media. Environmental Fate and Effects Division, Office of Chemical Safety and Pollution Prevention. U.S
. Environmental Protection Agency. US EPA. 20 12c. Development and Use of Percent Cropped Area and Percent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update http: / / www.epa.go v/oppefed 1/mode l s/ water /pca adjustment dwa.html 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/oppefed1 /models/ water / US EPA. 2007. Coumaphos: Human Health Risk Assessment for Proposed Use on Honey and Hone ycomb. PC Code: 036501; Petition Number: 2E6504; DP Number: D315769. US EPA, 2000a. Memorandum: Revised Tier 1 Drinking Water Assessment for Coumaphos. Environmental Fate and Effects Division, Office of Prevention, Pesticides, and Toxic Substances. United States Environmental Protection Agency. DP Barcode: 0266513. US EPA, 2000b. Reregistration Eligibility Decision Addendum and FQPA Tolerance Reassessment Progress Report: Coumaphos. Office of Prevention, Pesticides, and Toxic Substances. United States Environmental Protection Agency. EPA 738-R-00-010. US EPA. 1998. Coumaphos-EFEO Reply to Registrant 's Rebuttal. Office of Prevention, Pesticides and Toxic Substances, DP Barcodes D230394 and 0239676 

### US EPA. 

### 1994. Coumaphos (36501) Reregistration Case No. 

### 0018. Product and Residue Chemistry Chapters for the Coumaphos Reregistration Eligibility Decision (RED) Document. DP Barcode D207352.Appendix A 10

### Surface Water RUN No. 1 FOR Coumaphos RATE (#/AC)

ONB(MULT) .220( .220 ) No
. APPS & INTERVAL

1 1 

### Model Outputs

ON Baregrond * INPUT VALUES * SOIL SOLUBIL APPL TYPE \CROPPED INCORP !toe (PPM ) (\DRIPT) AREA ( IN ) 5905.0 0
. 2 GRANUL ( • 0) 100.0
. 0
FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS

(FIELD) RAIN/RUNOPF (RESERVOIR) (RES.-EFF) METABOLIC COMBINED (RESER.) (RESER
. ) .00 2 N/A l. 38- 171.12 .00 171.12
UNTREATED WATER CONC (MICROGRAMS / LITER ( PPB )) Ver 1.1.0 JAN 1, 2007 PEAK DAY (ACUTE) CONCENTRATION 4.799

RUN No. 2 FOR Oxon

RATE ( #/AC )

ONB(MULT)

. 022 ( .022) No.APPS & INTERVAL

1 1 ANNUAL AVERAGE (CHRONIC) CONCENTRATION .704

ON Bare * INPUT VALUES * SOIL SOLUBIL APPL TYPE \CROPPED INCORP Koc ( PPM ) ( \DRIFT) AREA ( IN ) 2922
. 0 31.6 GRANUL( .0) 100
. 0
. 0
FIELD AND RESERVOIR HALPLIFE VALUES (DAYS) METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS

(FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) METABOLIC COMBINED (RESER.) (RESER.) 4
. 10 2 N/A .00

- . 00 8
. 20 8.20
UNTREATED WATER CONC ( NANOGRAMS / LITER ( PPTr) ) Ver 1.1.0 JAN 1 , 2007 PEAK DAY (ACUTE) CONCENTRATION 404
. 402 ANNUAL AVERAGE ( CHRONIC) CONCENTRATION 19
. 007

11Application rate (lb/acre) 0
. 220 

### Ground water
SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U. S. ENVIRONMENTAL PROTECTION AGENCY SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE SciGrow version 2 .3 chemical:Coumaphos time is 4/23/2013 16: 3: 4 Nwnber of applications Total Use (1b/acre/yr) Koc (ml/g) Soil Aerobic metabolism (days) 1.0 0
. 220 1
. 87E+03 365.0 groundwater screening cond (ppb) = 1. 72E-02 ************************************************************************

Application rate (lb/acre) 0
. 022 SciGrow version 2.3 chemical : Coumaphoxon time is 4/23/2013 16 : 3:53 Nwnber of applications Total Use (lb/acre/yr) Koc (ml/g) Soil Aerobic metabolism (days) 1
. 0 0
. 022 2
. 56E+03 4.1 groundwater screening cond (ppb) = 5
. 72E-05 

### • ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

12PRZM-GW

PR7M GW (Vcrs ton 1 0 1 )**~** 

### Jx!

---- -- -

Hit;tlest O¥yVl!AJe(ppb)**~** Sirula6onA.,.ageVl!AJefppb)**~ Ave~age**  B t eok

tlvough Tine (&lys) j l ncornplete I**Th ll>u** **!h>ut. ~**  Pent 8 1f!ol<tlvoughAvOfage fppb) l l neomple< e I 2.5 ,--- -..,..------ ----------,



### I SoveGtaph 

### I I Cop)'Gtaph 

### I 

# I Run Sindoticn 

# I**1/0F ~Aa** **amo: N~** **Col1<>n 1(i(lyJs**  1/0 WOJking Drect OI)I: C : \Modeh\pr2mgw\Coumophos\

North Carolina**PRZMGW(Vcmon1.0 )**  1::.1 

### J'X

P
..

ticide Scenario: Gen01ol Scenario: Horizon C""'96olion S'""'" ary 0Up<Jt L------, Note : T ine serie• output is de§veted to the -'<i1g dwectOI)' speclied below
. H igheot Daly Value (ppb) J B
.7SE • 11**SirulotionAve~ageValuefppb)** j 5.7E · 11 l E- 10 · ,------------------,



### I Save Graph 

### I l Copy Graph 

### I 110 FqFiloName: FLCitrur_OJ<On...101¥t 110 Wcxl<ng DrectOI)I:**C:\Models~\**

Florida (Central Ridge) 

### 13

### Appendix B 

### Coumaphos Aerobic Soil metabolism
Days Percent AR

0 99.3 0 99.5 0 99.7

1 96.8 80

c:

· 2 60**~** 4

·2
4 2 1 99
. 0 1 99
. 0 c Q) (.)**...:__---x- --S+-**  0 3 98
. 0 3 98
. 9 3 97.0 7 98
. 9 7 98.9 7 96.1 14 97
. 8 14 97.8 14 98
. 7 30 98
. 5 60 96.5 90 91
. 3 120 !=lR R § 40 (_) 20

0 100 200 300 0 100 200 3 00 Time**~~~** OT50 DToo 

## -l Co Parame ters FO 2761 9171 1
. 7 98.2 k = 0.000251 ·2

-2

:op NA NA 1.4 98.7 f"' 0
. 4 79, ko • 0
. 0023, k, = -0
. 000916 )RE 16459347678 194832180211 048451 0248402846886 1.5 98.8 N = 29.7, k= 4.82e-61 

### Figure 

### 1. Aerobic Soil Degradation Kinetics (MRID 48705501)



### 14