UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

PC Code: 036501 

DP Barcode: 409560 

Date: August 20, 2013 

MEMORANDUM 

SUBJECT: 

TO: 

FROM: 

Revised Drinking Water Assessment for the Registration Review of Coumaphos 

Wilhelmena Livingston, Chemical Review Manager, 

Risk Management and Implementation Branch IV 

Pesticide Re-evaluation Division (7508P) 

Sheila Piper , Chemist 

Registration Action Branch 6 

Health Effects Division (7509P) . ., c ~ g/'¥'/!3 

Faruque Khan, Ph.D., Semor Sc1ent1~ · 

Environmental Risk Branch I 

Environmental Fate and Effects Division 

APPROVED 

BY: Sujatha Sankula, Ph.D., Branch Chief l"lC0. 

l .. ~A --;;;;= ~ 

Environmental Risk Branch I (7507P) 

Environmental Fate and Effects Division 

This memorandum provides revised estimated drinking water concentrations (EDWC) of 

coumaphos and its oxygen analog coumaphoxon in surface water and groundwater in support of 

human 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. Coumaphos can be 

applied by dip vats, aerosol can, dustbags, hand-held dusters, hand-held sprayers, backrubber 

oiler, mechanical dusters, 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 dislodging of applied chemical from animal hides. 

Coumaphos is also 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 indoor use 

of coumaphos (e.g., to treat swine bedding) and the placement of coumaphos-treated strips in bee 

hives would not be considered in the drinking water assessment because they do not provide 

complete routes of exposure to surface waters or groundwater. 
In the previous assessments, the Environmental Fate and Effects Division (EFED) assumed that 

the disposal of bioremidiated coumaphos dip vat solution on non-agricultural land would be a 

major exposure route to drinking water sources for human consumptions. Since dried sludge 

generated in evaporation ponds containing bioremediated dip vat solution is discarded in a 

landfill by USDA APHIS (US EPA, 2008), EFED concludes that exposure via application of 

bioremediated spent dip vat solutions to land is not an exposure pathway for drinking water 

sources. Therefore, the application ofbioremediated spent dip vat solutions to land is not 

included in estimating EDWCs in surface water and groundwater. 

However, during a rain event, coumaphos wash-off from treated cattle can be potentially 

adsorbed into manure as well as transported as effluent from concentrated animal feeding 

operations (CAFOs) and pasture/rangeland. The EDWCs from runoff and wash-off were 

calculated using the maximum annual application rate (i.e., spray: 3 applications@ 0.021lb 

a.i./animal = 0.063 lb a.i./animal/yr)for cattle as well as data from acceptable registrantsubmitted studies (MRID 42512601) quantifying the fraction of coumaphos that becomes 

available for exposure after soaking a cow hide in water (i.e., wash-off fraction). Table 1 

provides application rates of coumaphos for selected scenarios. Since estimated application rate 

from rangeland runofi is approximately 38 times lower than the application rate coumaphos 

containing manure, the EDWCs are based on a single application of the highest coumaphos 

containing manure (i.e. 0.28 lbs a.i/ A) for land application. In general, application rate of manure 

recommendation is based on nutrients (i.e. nitrogen, phosphorus and potassium) requirement for 

crops. For this assessment, application rate for manure applied to pasture and rangeland are 

based on 250 lb total nitrogen/acre per year requirement for growing warm season perennial 

grass in Texas. It is also assumed that there is no surface water and groundwater intakes adjacent 

to CAFOs, therefore, runoff from CAFOs is not considered for drinking water assessment. 

Detailed descriptions and calculations of application rates for coumaphos were also provide in 

Appendix A. 

Table 1. Estimated Coumaphos Application Rates for Various Scenarios 

Sources of a.i. Wash-Off Maximum Single Number of Maximum Annual 

from Application Fraction Application Rate Applications/Year Application Rate 

Scenario (lb/A) (lb/A) 

Spray Application (3 applications (ti 0.02llb/AU) 

Manure applied to crop 0.38 0.28 1" 0.28 

land 0.21 0.1 6 1 0.16 

0.02 0.015 1 0.015 

Runoff from range land 0.38 0.0024 3 0.0072 

0.21 0.0013 3 0.004 

0.02 0.00013 3 0.0004 

AU= animal unit 

a Application rate can be split based on Total Nitrogen requirement during the growing season. 

The residues of concern (ROC) for human health risk assessment and for tolerance expression 

are coumaphos and its oxygen analog coumaphoxon (US EPA, 2007). A maximum conversion 

efficiency of coumaphos to coumaphoxon of 10.2% was derived from available data on 

photodegradation in water. This conversion efficiency was used to estimate a coumaphoxon 

application rate of 0.0285 lbs ai/ A for drinking water modeling. The EDWCs of coumaphos and 

coumaphoxon were generated using Tier II PRZM/EXAMS model for surface water and Tier I 

2 
SCIGROW (Screening Concentration in Ground Water Program). Pesticide Root Zone ModelGround Water model (PRZM-GW) was also used for ground water based on recent EFED 

guidance document dated '(US EPA, 2012a). 

The recommended EDWCs for surface water and groundwater are listed in Table 1. 

PRZM/EXAMS model predicted total coumaphos residue concentration (coumaphos + 

coumaphoxon) in surface water are not likely to exceed 2.38 J..tg/L coumaphos equivalent/L for 

the maximum peak concentration (acute) and 1.62 J..tg coumaphos equivalent/L for the average 

concentration (chronic). SCI-GROW and PRZM_ GW modeling results are listed in Table I. 

PRZM-GW predicted total coumaphos residue concentration in groundwater used as drinking 

water is not likely to exceed 2.81 J..tg coumaphos equivalent/L for the maximum peak 

concentration (acute) and 1.22 Jlg coumaphos equivalent/L for the average concentration 

(chronic). 

Table 1. Recommended EDWCs for Drinking Water risk assessment for Coumaphos 

and Coumaphoxon 

Source of Drinking Estimated Drinking Water concentration (J.tg/L) 

Water Acute Chronic Average 

chronic 

Coumaphos 

Surface Water' 2.38 1.62 1.06 

Groundwater· 2.81 - 1.22 

Coumaphoxon 

Surface Water 0.001 0.0001 3.52E-5 

Groundwater1

'J 0.002 - 0.0007 

Coumaphos Equivalents (Coumaphos+Coumaphoxon) 

Surface Water 2.38 1.62 1.06 

Groundwater• 2.81 - 1.22 

EDWCs based on PRZM/EXAMS model 2 EDWCs based on PRZM-GW model 3 Highest EDWCs derived from NC Cotton scenario 4 Highest concentrations of coumaphos oxon for acute and chronic are 0.02 flg/L and 0.006 flg/L respectively for 

the WI Corn scenario. Since coumaphos concentrations are the highest in NC Cotton scenario, for highest additive 

concentrations of coumaphos and coumaphos oxon were estimated from NC Cotton. 

In addition, PRZM-GW modeling was also performed with the estimated DTso of2761 days 

based on NAFT A Kinetic modeling procedure (US EPA, 20 12b) and yielded maximum 

concentrations of 14.0 J..tg/L and 5.5 J..tg/L for acute and chronic values respectively for 

groundwater using extended (100 yrs) weather data for NC Cotton scenario. These 

concentrations are approximately two to three orders of magnitude higher than the estimated 

acute (0.07 J..tg/L) and chronic (0.006 J..tg/L) concentrations using 30 year weather data for the NC 

Cotton scenario. In addition, there is an uncertainty related to the estimated DTso value, which is 

approximately 7X higher than duration of aerobic soil metabolism study and 15 to 23X higher 

than the reported field dissipation half-lives. Therefore, recommended groundwater 

concentrations based on 3X of duration of aerobic soil metabolism study provide reasonable 

concentrations in groundwater. 

3 
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 pests including ticks, 

scabies mites, lice, flies, fleece wonns and screw worms. Coumaphos can be applied by dip vats, 

aerosol can, dustbags, hand-held dusters, hand-held sprayers, backrubber oiler, mechanical 

dusters, 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 dislodging of applied chemical from animal hides. The indoor use of 

coumaphos (e.g., to treat swine bedding) and the placement of coumaphos-treated strips in bee 

hives would not be considered in the drinking water assessment because they do not provide 

complete routes of exposure to surface waters or groundwater. Therefore, EFED believes that the 

application of coumaphos containing manure on agricultural land would be a major exposure 

route for drinking water sources. 

A limited environmental fate database for coumaphos indicates that it is a persistent (DT5o of> 1 

year in aerobic soil) chemical and slightly mobile to hardly mobile (Koc=1874 to 10297 Llkg) in 

soil according to F AO classification of mobility in soil (F AO, 2000). The major pathway of 

coumaphos degradation appears to be photodegradation in water (DT5o of33 hours). A major 

degradate, oxygen analog, coumaphoxon, was detected in an aqueous photodegradation study at 

a maximum of 10.2% of applied chemical. Limited environmental fate data are available for 

coumaphoxon, which suggests that it is not a persistent compound in the terrestrial environment 

(DT so of 0.49 to 2.27 days) and mobile (Koc= 198.4 L/kg) in soil according to FAO classification 

of mobility in soil (F AO, 2000). Since the environmental fate data suggest that the fate behavior 

of coumaphos and coumaphoxon differ in the environment, EDWCs were estimated 

independently for these chemicals. 

Residues of Concern 

The residues of concern (ROC) for human health risk assessment and for tolerance expression 

are coumaphos and its oxygen analog coumaphoxon (US EPA, 2007). 

Models 

Surface Water 

The EDWCs were generated using EFED's standard suite of models. Pesticide Root Zone Model 

(PRZM v3.12.2, May 12, 2005) and Exposure Analysis Modeling System (EXAMS v2.98.04.06, 

Apr. 25, 2005). PRZM and EXAMS are simulation models coupled with the input shell 

PRZM/EXAMS (PE v5.0, Nov. 15, 2006) to generate EDWCs of coumaphos and its major 

degradate, coumaphoxon, that may occur in surface water used as drinking water. The PRZM 

model simulates pesticide movement and transformation from crop application through soil 

residue processes. The EXAMS model simulates pesticide loading via runoff and erosion 

assuming a standard watershed of 172.8 ha that drains into an adjacent standard drinking water 

index reservoir with surface area of5.26 ha and an average depth of2.74 m. A more detailed 

description of the index reservoir watershed can be found in Jones eta!., 1998. Standard percent 

4 
cropped areas (PC A) were used for proposed uses as estimates of the extent of watershed on 

which crops are grown. The national default for non-agricultural use (PCA of 1.0) was applied in 

this assessment according to the current PCA guidance (US EPA 20 12b ). 

Ground water 

Screening Concentration in Ground Water (SCI-GROW v2.3, Jul. 29, 2003) is a regression 

model used as a screening tool 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/#scigrow). 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 also derived using the PRZM-GW model (Pesticide Root Zone Model for 

Groundwater, version 1.0, August 31, 20 12), with the G W -GUI (Graphical User Interface, 

version 1.0, August 31, 2012). PRZM-GW is a one-dimensional, finjte-difference model that 

estimates the concentrations of pesticides 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 applied 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 contaminations, 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 supply that is located directly beneath a rural 

agricultural field following many years of pesticide application. 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/waterD. 

Input Parameters 

A summary of the model input parameter values used in PRZM/EXAMS, SCI-GROW, and the 

PRZM_ OW Models are in Table 2, Table 3, and Table 4, respectively. Input parameters were 

selected in accordance with EFED's "Guidance for Selecting Input Parameters in Modeling the 

Environmental Fate and Transport of Pesticides," Version 2.1 (USEPA, 2009). Sample model 

output files are located in Appendix C. PRZMIEXAMS Time series for coumaphos and 

coumaphoxon for P A Turf scenario were also attached in Appendix C. 

Table 2. PRZMIEXAMS input parameters for coumaphos and coumaphoxon 

Parameter Value Data Source Comments 

Coumaphos 

Maximum application See Appendix A 

Rate lb a.i./A (kg 0.28 (0.31) Estimated 

a.i./ha) 

5 
Table 2. PRZMIEXAMS input parameters for coumaphos and coumaphoxon 

Parameter Value Data Source Comments 

Assumed, however, application rate 

Number of Applications I can be split based on Total 

Nitrogen requirement during the 

growing season. 

Depth of Incorporation 0 Assumed 

(inches) 

Method of Application Ground spray 

common practice for application of 

manure 

Spray Drift 0 Applied as manure 

Application Efficiency 1.0 Assumed Applied with manure spreader 

Scenario and PA Turf, 15-10 Based on Assumed manure applied during 

Application Date FL Turf, 15-10 PRZMIEXAMS dormant season 

(day-month) BSS Turf, 15-1 0 Scenarios 

Molecular Mass (g/mol) 362.5 US EPA2007 ---

Vapor Pressure (Torr) l.OE-07 US EPA2007 ---

Henry's Law Constant 2.62E-07 Estimated -

(atm m3/mol) 

Solubility in Water 20 US EPA 2007 --- (mg/L) 

Hydrolysis t112 at pH 7.0 0 Not Available Considered stable to hydrolysis @ 

(days) pH 7.0 

Aquatic Photolysis t 1n 1.38 MRID 42764101 Coumaphoxon is a major degradate 

(days) MRID 4310390 I (10.2%) 

Aerobic Soil 0 MRID 40518701 Considered stable 

Metabolism t1n (d) 

Aerobic Aquatic 0 --- Input parameter guidance (USEP A, 

Metabolism t1n (d) 2009) 

Soil Partitioning 5904 

MRID 45721401 Represent average Kroc from 4 soils 

Coefficient (Koc; ml/g0 ) 

Wetted in? No -- Assumed 

Percent Crop Area 

US EPA 2012c 

Recommended PCA for non 

1.0 agricultural uses (Decimal) 

Coumaphoxon 

Maximum application 

Rate lb a.i./ A (kg 0.0285 (0.031) Estimated• ---

a.i./ha) 

6 
Table 2. PRZMIEXAMS input parameters for coumaphos and coumaphoxon 

Parameter Value Data Source Comments 

Number of Applications 1 Assumed Based on application rate of 

coumaphos 

Depth oflncorporation 0 Assumed __ ,_ 

(inches) 

Method of Application Not applicable -- Degradation product of coumaphos 

PA Turf, 15-10 Based on 

Scenario and FL Turf, 15-10 PRZM/EXAMS Assumed manure applied during 

Application Date BSS Turf, 15-10 Scenarios dormant season 

Molecular Mass (glmol) 346.7 EPISUITE Estimated value 

Vapor Pressure (Torr) 7.68E-08 EPISUITE Estimated value 

Henry's Law Constant 1.10E-09 EPISUITE Estimated value (atm m3/mol) 

Solubility in Water 31.6 EPISUITE 4. I Estimated value (mg!L) 

Hydrolysis t 112 at pH 7.0 0 (days) 

Not available Assumed stable 

Aquatic Photolysis t 112 0 Not available Assumed stable (days) 

Aerobic Soil 90th percentile upper confidence 

Metabolism DT 5o (d) 4.1 MRID 48705501 bound on the mean half-life of 

coumaphoxon 

Aerobic Aquatic 8.i~ --- 2X of Aerobic Soil Metabolism 

Metabolism t 112 (d) DTso (days) 

Soil Partitioning 198.4 Coefficient (Ko.; mV~) 

EPISUITE 4.1 Estimated value 

Percent Crop Area 1.0 US EPA 2012c Recommended PCA for non 

(Decimal) agricultural uses 

• Coumaphos application rate (0.28 lb a.i/A) x [(0.1 02, the maximum conversion rate from aquatic photolytic 

degradation of coumaphos to coumaphoxon in laboratory studies) x (0.96, the molecular weight ratio of 

coumaphos to coumaphoxon)] 

b In absence of aerobic aquatic metabolism study, 2X of aerobic soil metabolism DT 50 value was multiplied by 2 

according to Guidance for selecting input parameters in modeling for environmental fate and transport of 

pesticides. Version 2.1 October 22, 2009. 

Table 3. SCI-GROW (v2.3) Input Parameter Values for Coumaphos and Coumaphoxon 

Parameter I Value I Data Source I Comments 

Coumaphos 

Application Rate (lbs I 0.28 I Table2 I --- a. i./acre) 

7 
Table 3. SCI-GROW (v2.3) Input Parameter Values for Coumaphos and Coumaphoxon 

Parameter Value Data Source Comments 

Number of I US EPA, 1998 See Table 2 applications 

Since there is a threefold difference in 

KFoc (mL!g) 1870 MRID 45721401 observed values, lowest non-sand KFoc 

value used. 

Aerobic soil MRID45118631 metabolism DT50 0 Stable 

(days) 

Coumaphoxon 

Maximum application 

Rate lb a.i./A (kg 0.0285 (0.031) Table2 --- a.i./ha) 

Number of Table 2 applications ---

Koc (mL/g) 198.4 EPISUITE 4. 1 Estimated value 

Aerobic soil 4.1 MRID 48705501 9001 percentile upper confidence bound 

metabolism (DT50) d on the mean half-life of coumap_hoxon 

Table 4. PRZM-GW (vl.O) Input Parameter Values for Coumaphos and Coumaphoxon 

Data Source Comments Parameters Value 

Application Method Ground Table2 ---

Application Rate 0.0285 [0.031] Table 2 --- (lbs. a.i./acre) [kg/ha] 

Application 1 Table2 --·- Frequency 

Hydrolysis (DTso) d Stable --·- No study 

Aerobic soil 10951 MRID 451 18631 Stable. Assumed 3X of duration of 

metabolism (DT50) d study 

Koc 2922 L/Kg MRID 4680841 1 Average KFoc 2 

Coumaphoxon 

Application Method Ground Table2 ---

Application Rate 0.0285 [0.031] Table2 --- (lbs. a.i./acre) [kg/ha] 

Application I Table2 --- Frequency 

8 
Table 4. PRZM-GW (vl.O) Input Parameter Values for Coumaphos and Coumaphoxon 

Data Source 

Parameters Value Comments 

Hydrolysis (DTso) d 0 Not available Assumed stable

2 

Aerobic soil 4.1 2 MRJD 4870550 I 9oth percentile upper confidence bound 

metabolism (DT so) d on the mean half-life of coumapboxon 

Koc 198.4 EPISUITE 4.1 Estimated value 

1 Model requires a numerical value other than 0. DT50 was estimated using the NAFT A degradation kinetics 

procedure and did not have a recommendation for modeling (Figure l, Appendix B). In addition, the estimated 

Single First Order (SFO) DT50 of2761 days is well beyond the duration of study. 

2 EFED input parameter guidance: 

htto://www.eoa.!wv/oooefedl/models/water/orzm !?.w/watt orzm ow innut !?.uidance.htm 

Results 

Estimated coumaphos concentrations in surface water and ground water used for drinking water 

are summarized in Table 5 and 6. Sample outputs from model runs are provided in Appendix 

c. 

PRZMIEXAMS model concentrations (f.lg/L) represent untreated surface water ~oncentrations. The 

SCIGROW and PRZM-GW concentrations represent groundwater concentration that might be expected 

in shallow unconf"med aquifers under sandy soils. All scenarios run in PRZM-GW required the use of an 

extended weather file, which allows the user to run the simulation for up to 1 00 years in order to observe 

breakthrough. 

The simulated concentrations provided in this assessment are conservative estimates of concentrations in 

drinking water. If dietary risks require refinement, higher-tiered, crop-specific and location-specific 

models and modeling scenarios can be used. 

Table 5. PRZMIEXAMS EDWCs Based on Manure Containing Coumaphos and its 

Degradate Coumapboxon application 

1-in-10 year 1-in-10 year 

I 

30- year annual 

Drinking Water Source Crop Scenario acute chronic average 

I (f.lg/L) (f.lg/L) (f.lg/L) 

Coumaphos 

Surface Water 1 BSS Turr 0.42 0.02 0.01 

FL Turf 1.65 0.85 0.64 

PA Turf 2.38 1.62 0.64 

Ground water NC Cotton 2.81 Not Applicable 1.22 Scenario2 

Generic 3.96 E-02 3.96 E-02 3.96 E-02 Scenario3 

Coumaphoxon 

Surface Water BSS Turr 1 o.42 0.02 0.01 

9 
Table 5. PRZMIEXAMS EDWCs Based on Manure Containing Coumaphos and its 

Degradate Coumaphoxon application 

1-in-10 year 1-in-10 year 30- year annual 

Drinking Water Source Crop Scenario acute chronic average 

(p.g/L) (Jtg/L) (Jtg/L) 

FL Turf l.OE-03 4.48E-05 3.52E-05 

PA Turf l.49E03 1.33E-04 3.52E-05 

Ground water WI Com 0.58 Not Applicable 6.0E-03 Scenario2 

GenericScenario5 1.04£04 1.04£04 1.04£04 

EDWCs generated using PRZM/EXAMS model 2 Highest EDWCs generated using PRZM-GW model, 3 EDWCs generated using SCIGROW model and can be considered for both acute and chronic values 

Table 6. PRZM-GW EDWCs EDWCs Based on Manure Containing Coumaphos and its 

De~radate Couma >hoxon application 

Application Rate and Highest Post Average Simulation 

Scenario1 Daily Breakthrough Breakthrough Time Frequency Value (~giL) Average (~giL) (days) 

Coumaphos 

FL Citrus 0.45 0.10 Incomplete 

FL Potato 4.98E-05 7.62E-05 Incomplete 

GA peanut 3.87E-05 2.46E-06 Incomplete 

NC Cotton 2.81 1.22 Incomplete 

14.0:l 5.49:l Incomplete 

Delmarva sweet com 0.53 0.08 Incomplete 

WI com 0.58 0.01 Incomplete 

Couma >hoxon 

0.028 lbs a.i./A x FL Citrus 3.3E-04 9.81E-05 2464 

I applications FL potato l.04E-08 1.28E-09 4574 

GA peanut 1.3E-04 6.6E-05 4502 

NC cotton 2.7£-03 7.0£-04 2034 

Delmarva sweet com 5.0E-03 3.0E-03 1806 

WI com 0.02 6.0E-03 2610 

These scenarios are regional vulnerable sites for groundwater evaluation. 2 These EDWCs are based on aerobic soil metabolism DT50 of2761 days 

Monitoring Data 

There was no national-scale or state monitoring data available for this assessment. 

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 drinking water assessment is the lack of acceptable 

environmental fate data for coumaphos and its degradate coumaphoxon. Limited data available 

10 
for coumaphos and it's degradate, coumaphoxon. 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 0.0285 lbs ai/ A. 

In addition, there is an additional uncertainty related to the estimated DT5o value, whi~h is 

approximately 7X higher than duration of aerobic soil metabolism study and 15 to 23X higher 

than the reported field dissipation half-lives. Groundwater concentrations were based on 3X of 

duration of aerobic soil metabolism study. 

In this drinking water assessment, EFED has attempted to locate the best available data regarding 

how to estimate coumaphos embedded in manure and potential runoff fraction from pastures and 

rangelands. Frequently, such information is better expressed as ranges rather than points, and 

when this is the case, EFED typically opts to use the end of range which would result in the high 

end estimate ofEDWCs in order to ensure protection of human health risk from drinking water. 

11 
References 

ASAE. 2005. Manure Production and Characteristics. ASAE Standard D384.1 FEB 03.Arnerican 

Society of Agricultural Engineers. St. Joseph, MI 

F AO 2000. Appendix 2. Parameters of pesticides that influence processes in the soil. In F AO 

Information Division Editorial Group (Ed.), Pesticide Disposal Series 8. Assessing Soil 

Contamination. A reference Manual, Rome: Food and Agricultural Organization of the 

United Nations. Available at http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm 

(Accessed April I 0, 20 13). 

USDA. 2008. Agricultural Waste Management Field Handbook, Part 651. Natural Resources 

Conservation Services, U.S. Department of Agriculture, Washington, D.C. 

US EPA. 2008. Memorandum: EFED Response to Comments for Coumaphos Registration 

Review Regarding Data Needed to Refine Ecological Risk Assessment Environmental 

Fate and Effects Division, Office of Chemical Safety and Pollution Prevention. U. S. 

Environmental Protection Agency (DP Barcode D347373). 

US EPA. 2012a. Memorandum: Approval ofPRZM-GW for use of Drinking Water Exposure 

Assessment. Environmental Fate and Effects Division, Office of Chemical Safety and 

Pollution Prevention. U.S. Environmental Protection Agency. 

US EPA. 20 12a. Memorandum: NAFT A 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. 2012b. Development and Use of Percent Cropped Area and Percent Turf Area 

Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update 

http://www .epa. gov I oppefed 1 /models/water/pea adjustment dwa.html 

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

and Transport of Pesticides, Version II. U.S. Environmental Protection Agency. 

Washington, D. C. http://www .epa. gov I oppefed 1 /models/water/ 

US EPA. 2007. Coumaphos: Human Health Risk Assessment for Proposed Use on Honey and 

Honeycomb. PC Code: 036501; Petition Number: 2E6504; DP Number: D315769. 

US EPA, 2000. Reregistration Eligibility Decision Addendum and FQPA Tolerance 

Reassessment Progress Report: Coumaphos. Office of Prevention, Pesticiqes, and Toxic 

Substances. United States Environmental Protection Agency. EPA 738-R-00-010. 

US EPA. 1998. Coumaphos-EFED Reply to Registrant's Rebuttal. Office of Prevention, 

Pesticides and Toxic Substances, DP Barcodes D230394 and D239676 

12 
US EPA. 1994. Coumaphos (3650 1) Reregistration Case No. 0018. Product and Residue 

Chemistry Chapters for the Coumaphos Reregistration Eligibility Decision· (RED) 

Document. DP Barcode D207352. 

13 
Appendix A 

In registrant-submitted wash-off studies, fresh cow hides were treated with either Co-Ral® 

11.6% emulsifiable liquid (MRID 42512601) or Co-Ral® 25% wettable powder (MRID 

42512602) and then dried for 0.5, 3, or 24 hours. The wash-off fraction was measured after 

hides had been soaked in water for 0.5, 1, 1, or 4 hours. Results of these studies indicate that 

wash-off fraction is inversely related to drying times and dependent upon the formulation (Table 

A-1) but not affected by soaking time (data not shown). Wash-off fractions for the wettable 

powder!flowable concentrate are used in the assessment since they are generally more 

conservative than those for the emulsifiable powder/concentrate. 

Table A-1. Percent Wash-Off for Different Formulations of Coumaphos at Different 

Drying Times (MRIDs 42512601 and 42512602) 

Formulation(%) Drying Time (brs) Wash-Off Fraction• 

Emulsifiable powder/concentrate 

0.5 0.116 

3 0.046 ( 11.6) 24 0.027 

Wettable powderlflowable 0.5 0.38 .., 0.21 concentrate ( 42) .) 

24 0.20 

• used m the aquatic exposure assessment 

To accurately characterize the potential environmental exposure pathways, selecting the 

appropriate livestock management system and various exposure pathway scenarios is necessary. 

Two scenarios were considered to estimate the application rate of coumaphos for drinking water 

assessment. The following scenarios and example calculations of application rates are based on 

spray application on cattle. Table A-2 provides application rates for various scenarios. 

T a e bl A 2 - . E shmate . dC oumap h os A ppir lcahon R ates ~ or v . anous s cenar10s 

Sources of a.i. Wash-Off Maximum Single Number of 

from Applica tion Fraction Application Rate Applications/Year 

Scenario (lb/A) 

Spray Application (3 ap])lications @0.02llb/AU} 

Manure applied to crop 0.38 0.28 1" 

land 0.21 0.16 1 

0.02 0.015 I 

Runoff from range land 0.38 0.0024 3 

0.21 0.0013 3 

0.02 0.00013 3 

Dip Vat Application (2 applications@ 0.027 lb/AU) 

Manure applied to crop 0.38 0.24 I 

land 0.21 0.13 1 

0.02 0.013 1 

Runoff from range land 0.38 0.0031 2 

0.21 0.0017 2 

0.02 0.0002 2 

AU = anunal umt 

a Application rate can be split based on TN requirement during the growing season. 

b Three or two applications/stocking period; maximum four stocking periods based on 

http://www.epa.gov/agriculture/agl 0 I /beefuroducts.html 

14 

Maximum Annual 

Application Rate 

(lb/A) 

0.28 

0.16 

0.015 

0.0072 

0.004 

0.0004 

0.024 

0.0130 

0.0013 

0.0062 

0.0034 

0.0004 
Example Calculation: Manure from CAFOs (Concentrated Animal Feeding Operation) 

Manure is a valuable soil amendment/organic fertilizer for any farming operation and has been 

used for centuries to supply needed nutrients for crop growth. Manure not only supplies many 

beneficial nutrients for crop production, but could also be a potential source for pesticides that 

are embedded into manure from wash-off from treated livestock. Application rate of coumaphos 

was estimated based on dry weight of manure application for crop production. The following 

steps were used to calculate the application rate of coumaphos. 

Step 1: Total Dry Weight of Manure (DM)/AU(animal unit)lyear 

OM= 8.5 lb solid in manure [ASAE, 2003] /AU x 365 days= 3103 lb dry manure/AU/year 

or 1.55 tons/AU/year 

Step 2: Active Ingredient in manure (AM) lb a.i.!AU 

AM = (Ax F x S x W x PA) lb a.i./AU/year 

Where: 

A = application rate: 0.021lb/AU for spray application 

F =frequency of application: 3/AU/year 

S = # of stocking/year: 4 (Based on 90-120 days stocking period for cattle in feedlot 1

) 

W =wash-off fraction: 0.02 to 0.38 (MRIDs 42512601 and 42512602) 

PA =potential adsorption of coumaphos in manure: 0.36 (assumed based on EPISUITE 

estimate for adsorption into sludge) 

Sample calculation: 

AM = (0.021 x 3 x 4 x 0.38 x 0.36) = 0.034 a.i. lb/AU 

Step 3: Active ingredient in manure (lb a. i./ton) 

(0.034 a.i. lb/1.55 ton manure) = 0.022 lbs a.i./ton dry manure 

Step 4: Total Nitrogen Production (TN) per animal (lbs TNIAU/year) 

TN= (N x L x V x D) lbs TN/ AU/year 

Where: 

N =nitrogen content in manure per AU (TN lb/AU) (ASABE, 2003) 

L = average fraction ofN retained during storage and handling: 0.5 (Table 11.5, USDA, 

2008) 

V= Fraction ofN loss due to volatilization: 0.5 (Table 11.6, USDA, 2006) 

D = 365 of days /year 

Sample calculation: 

1 http://www.epa.gov/agriculture/ag I 0 I /beefuroducts.htm I 

15 
TN= (0.34 x 0.5 x 0.5 x 365) = 31 lbs TN in manure/AU/year 

Step 5: Total N in manure (lblton manure) 

(31lbs TN/1.55 ton manure) = 20 lb TN/ton manure/AU 

Step 6: Application Rate of Manure (ton/acre) 

In general, application rate of manure based TN recommendation for crop types. For example, 

250 lb TN/acre per year requires for growing warm season perennial grass in Texas2

. 

Sample calculation: 

(250 lbs TN/acre) x (1 ton Manure /20 lbs TN) 

12.5 tons manure/acre require for growing perennial grass in Texas 

Step 7: Application rate of active ingredient (lblacre) 

(0.022lbs a.i/ton) x (12.5 tons manure/acre)= 0.28 lbs a.i./acre 

Therefore, the application rate of0.28lbs a.i/A is based on 38% coumaphos wash-off from 

treated cattle. Table A-2 provides application rates per acre based on various wash-off fractions. 

1.1.1 Example Calculation: Non-Regulated Small CAFO ~ 300 cattle 

Runoff of washed-off coumaphos from treated cattle could be a major contributor from an open 

non-regulated feedlot. Application rate was estimated from runoff contribution based on washoff fraction of coumaphos and animal density per acre. The following equation was used in 

calculating application rate: 

Application Rate (AR) of active Ingredient (lb/ A) 

AR (lb a.i./ A) = (A x F x S x C x W x PR X FF) 

Where: 

A = application rate: 0.021 a.i. lb/AU (spray application) 

F =frequency of application: 3 (spray application) 

S = # of stocking/year: 4 (Based on 90-120 days stocking period for cattle in feedlot3

) 

C =#of AU in feedlot: 300 (Murphy and Harner, 2006) 

W =wash-off fraction: 0.02 to 0.38 (MRIDs 42512601 and 42512602) 

PR =potential removal through adsorption of coumaphos into manure: 0.64 (1-0.36) 

(based on EPISUITE estimate for adsorption of coumaphos into sludge) 

FF = fraction of feedlot for 10 hectare scenario: 0.1 (based on 3 acres (1 ha) for 300 AU, 

where density of 1 00 cattle/acre; Murphy and Hamer, 2006) 

Sample calculation: 

AR = (0.021x 3 X 4 X 300 X 0.38 X 0.64 X 0.1) = 1.82lb a.i./A 

2 Stichles and McFarland, http://agrilifeextension.tamu.edu/ 

3 http://www.epa.gov/agriculture/ag I 0 1/beefuroducts.htm I 

16 
1.1. 2 Example Calculation: Cattle Grazing in Rangeland 

Runoff of washed-off coumaphos from treated cattle could be major contributor from treated 

cattle grazing on rangeland. Application rate was estimated from runoff contribution based on 

wash-off of coumaphos and animals stocking rate per acre. 

Application Rate (AR) of active Ingredient (lbs/ Acre) 

AR = (A X F X c X W) 

A = application rate: 0.021 lb/ AU (spray application) 

F = frequency of application: 3 (spray application) 

C = # of AU in pasture/land: 0.3 (Pratt and Rasmaussan, 2001) 

W =wash-off fraction: 0.02 to 0.38 (MRIDs 42512601 and 42512602) 

Sample calculation: 

AR = (0.021 X 3 X 0.3 X 0.38) = O.OOTi lb/A 

17 
Appendix B 

Coumaphos Aerobic Soil metabolism 

Days Percent AR 

0 99.3 

0 99.5 c 0 99.7 ~ 

1 96.8 ~ 1 99.0 E 

1 99.0 Q) 

<-> 3. 98.0 c 

3 98.9 C) 

(..) 

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 !1R A 

...,.,,.., 

180 DT60 

FO 2761 

- . ..... ""' 

80 -

60 -

40 -

20 - -- SFO I --- DFOP 

• • • • • · lORE 

0 

0 100 

.... 

200 

Time 

.. 

300 

1."1. Co 

1.7 98.2 

-· e.t • / 

• ~ • 

• 

••• .. f • • - • 

• ...... _.,... _,,- .. 

.......... -·· • • • 

0 100 200 300 

Parameters 

k; 0.000251 

4 

2 

0 

·2 

-4 

4 

0 

·"'. 

·4 

4 

2 

0 

·2 

·4 

=oP NA 

DT90 

9171 

NA 1.4 98.7 f- 0.479, kg&0.0023, k,= -0.000916 

)RE 1645934 7678 194832180211 048451 0248402846886 1.5 98.8 N • 29.7, k• 4.82e·61 

Figure 1. Aerobic Soil Degradation Kinetics (MRID 48705501) 

18 
Appendix C-Model Outputs 

Surface Water 

Sample PRZM!EXAMS Output 

Coumaphos 

stored as PA_M38_D.out 

Chemical: Coumaphos 

PRZM environment: PAtuifSTD.txt 

modified Thuday, 23 February 2006 at 18:55:08 

EXAMS environment: ir298.exv 

modified Tueday, 26 August 2008 at 06:14:08 

Metfile: w14751.dvfmodified Tueday, 26 August 2008 at 06:15:00 

Water segment concentrations (ppb) 

Year Peak 96hr 21 Day 60Day 90Day Yearly 

1961 0.01 0.01 0.01 0.00 0.00 0.00 

1962 0.24 0.22 0.17 0.12 0.11 0.04 

1963 0.37 0.35 0.28 0.25 0.19 0.12 

1964 0.33 0.31 0.28 0.24 0.23 0.21 

1965 0.83 0.77 0.59 0.47 0.42 0.33 

1966 1.45 1.34 1.03 0.77 0.71 0.52 

1967 0.88 0.86 0.77 0.70 0.68 0.63 

1968 1.47 1.38 1.13 0.91 0.86 0.71 

1969 2.39 2.21 1.84 1.36 1.22 0.89 

1970 1.35 1.30 1.18 1.07 1.04 0.99 

197 1 1.46 1.40 1.23 1.12 1.07 1.00 

1972 6.01 5.47 3.98 2.74 2.39 1.58 

1973 2.16 2.10 1.92 1.78 1.74 1.70 

1974 1.81 1.79 1.75 1.72 1.69 1.63 

1975 3.23 3.04 2.51 2.06 1.93 1.60 

1976 2.22 2.14 1.97 1.78 1.73 1.65 

1977 1.81 1.79 1.75 1.69 1.67 1.57 

1978 1.64 1.62 1.58 1.55 1.55 1.47 

1979 2.33 2.23 1.97 1.77 1.70 1.52 

1980 1.79 1.74 1.61 1.51 1.45 1.39 

1981 1.65 "1.62 1.53 1.47 1.46 1.37 

1982 1.98 1.90 1.75 1.56 1.48 1.33 

1983 2.04 1.95 1.70 1.37 1.32 1.27 

1984 1.56 1.53 1.46 1.38 1.37 1.32 

1985 1.48 1.46 1.39 1.31 1.29 1.23 

1986 1.48 1.44 1.34 1.24 1.22 1.19 

1987 1.75 1.68 1.49 1.29 1.24 1.16 

19 
1988 1.29 1.26 1.24 1.22 1.21 l.l4 

1989 1.47 1.43 1.32 1.22 1.19 1.13 

1990 1.60 1.55 1.42 1.34 1.27 1.19 

Sorted results 

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

0.03 6.01 5.47 3.98 2.74 2.39 1.70 

0.06 3.23 3.04 2.51 2.06 1.93 1.65 

0.10 2.39 2.23 1.97 1.78 1.74 1.63 

0.13 2.33 2.21 1.97 1.78 1.73 1.60 

0.16 2.22 2.14 1.92 1.77 1.70 1.58 

0.19 2.16 2.10 1.84 1.72 1.69 1.57 

0.23 2.04 1.95 1.75 1.69 1.67 1.52 

0.26 1.98 1.90 1.75 1.56 1.55 1.47 

0.29 1.81 1.79 1.75 1.55 1.48 1.39 

0.32 1.81 1.79 1.70 1.51 1.46 1.37 

0.35 1.79 1.74 1.61 1.47 1.45 1.33 

0.39 1.75 1.68 1.58 1.38 1.37 1.32 

0.42 1.65 1.62 1.53 1.37 1.32 1.27 

0.45 1.64 1.62 1.49 1.36 1.29 1.23 

0.48 1.60 1.55 1.46 1.34 1.27 l.l9 

0.52 1.56 1.53 1.42 1.31 1.24 1.19 

0.55 1.48 1.46 1.39 1.29 1.22 1.16 

0.58 1.48 1.44 1.34 1.24 1.22 1.14 

0.61 1.47 1.43 1.32 1.22 1.21 1.13 

0.65 1.47 1.40 1.24 1.22 1.19 1.00 

0.68 1.46 1.38 1.23 1.12 1.07 0.99 

0.71 1.45 1.34 1.18 1.07 1.04 0.89 

0.74 1.35 1.30 1.13 0.91 0.86 0.71 

0.77 1.29 1.26 1.03 0.77 0.71 0.63 

0.81 0.88 0.86 0.77 0.70 0.68 0.52 

0.84 0.83 0.77 0.59 0.47 0.42 0.33 

0.87 0.37 0.35 0.28 0.25 0.23 0.21 

0.90 0.33 0.31 0.28 0.24 0.19 0.12 

0.94 0.24 0.22 0.17 0.12 0.11 0.04 

0.97 0.01 0.01 0.01 0.00 0.00 0.00 

0.10 2.38 2 .23 1.97 1.78 1.74 1.63 

Average 1.06 

of yearly 

averages: 

Inputs generated by pe5.pl- Novemeber 2006 

Data used for this run: 

20 
Output File: PA_M38_ D 

Metfile: wl475l.dvf 

PRZM PAturfSTD.txt 

scenario: 

EXAMS ir298.exv 

environme 

nt file: 

Chemical Coumaphos 

Name: 

Descriptio Variable Value Units Comments 

n Name 

Molecular mwt 362.5 g/mol 

weight 

Henry's henry 2.62E-09 atm-m/\3/mol 

Law 

Con st. 

Vapor vapr l.OOE-07 torr 

Pressure 

Solubility sol 20 mg/L 

Kd Kd mg/L 

Koc Koc 5904 mg!L 

Photolysis kdp 1.38 days Half-life 

half-life 

Aerobic kbacw 0 days Hal fife 

Aquatic 

Metabolis 

m 

Anaerobic kbacs 0 days Hal fife 

Aquatic 

Metabolis 

m 

Aerobic asm 0 days Hal fife 

Soil 

Metabolis 

m 

Hydrolysi pH7 0 days Half-life 

s: 

Method: CAM integer See PRZM manual 

lncorporat DEPI em 

ion Depth: 

Applicatio TAPP 0.31 kg/ha 

n Rate: 

Applicatio APPEFF fraction 

n 

Efficiency 

Spray DRFT 0 fraction of application rate applied to pond 

Drift 

Applicatio Date 15-10 dd/mm or dd/mmm or dd-mm or dd-mmm 

n Date 

Record FJLTRA 

17: 

IPSCND 

UPTKF 

21 
Record PLVKRT 

18: 

PLDKRT 

FEXTRC 0.5 

Flag for IR Reservoir 

Index Res. 

Run 

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

runoff 

calc. 

Coumaphoxan 

stored as PA_Oxon.out 

Chemical: Coumaphos Oxon 

PRZM environment: PAturfSTD.txt 

modified Thuday, 23 February 2006 at 18:55:08 

EXAMS environment: pond298.exv 

modified Tueday, 26 August 2008 at 06:14:08 

Metfile: w14751.dvf 

modified Tueday, 26 August 2008 at 06:15:00 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 2.80E-04 2.63E-04 2.06E-04 1.16E-04 8.07E-05 2.06E-05 

1962 2.91E-05 2.78E-05 2.31E-05 1.67E-05 1.24E-05 3.40E-06 

1963 9.67E-05 9.17E-05 7.44E-05 4.68E-05 3.40E-05 8.82E-06 

1964 2.62E-05 2.50E-05 2.02E-05 1.58E-05 1.20E-05 3.16E-06 

1965 5.26E-04 5.04E-04 4.22E-04 2.81E-04 2.04E-04 5.27E-05 

1966 1.92E-06 1.92E-06 1.87E-06 1.71E-06 1.53E-06 4.96E-07 

1967 3.51E-04 3.37E-04 2.84E-04 1.85E-04 1.39E-04 3.61E-05 

1968 2.33E-04 2.16E-04 1.57E-04 8.38E-05 5.78E-05 1.52E-OS 

1969 1.82E-04 1.74E-04 1.37E-04 7.85E-05 5.53E-OS 1.43E-OS 

1970 2.81E-03 2.62E-03 1.99E-03 1.12E-03 7.80E-04 1.99E-04 

1971 1.58E-05 1.53E-05 1.30E-05 9.14E-06 8.72E-06 3.34E-06 

1972 6.3SE-07 5.75E-07 3.92E-07 2.03E-07 1.60E-07 7.31E-08 

1973 1.97E-04 1.84E-04 1.40E-04 8.28E-OS 5.84E-05 1.49E-OS 

1974 3.90E-04 3.67E-04 3.01E-04 1.69E-04 1.19E-04 3.06E-05 

1975 2.20E-04 2.08E-04 1.57E-04 1.03E-04 8.22E-05 2.18E-05 

1976 4.16E-06 3.80E-06 2.66E-06 1.44E-06 1.26E-06 5.36E-07 

1977 1.52E-03 1.44E-03 1.18E-03 7.64E-04 5.65E-04 1.47E-04 

1978 9.52E-04 9.10E-04 7.16E-04 4.97E-04 3.6SE-04 9.53E-05 

1979 3.70E-06 3.70E-06 3.63E-06 3.35E-06 2.99E-06 1.01E-06 

1980 2.13E-04 2.03E-04 1.63E-04 l.OOE-04 7.17E-05 1.84E-05 

1981 8.20E-07 8.15E-07 7.88E-07 7.05E-07 6.28E-07 2.01E-07 

1982 8.62E-05 8.11E-05 6.36E-05 3.73E-05 2.68E-05 6.91E-06 

22 
1983 1.56E-03 1.46E-03 1.22E-03 7.32E-04 5.13E-04 1.34E-04 

1984 8.23E-04 7.74E-04 6.53E-04 4.25E-04 3.05E-04 7.97E-OS 

1985 9.54E-05 8.64E-05 6.00E-05 3.14E-05 2.19E-05 6.45E-06 

1986 1.1SE-03 1.09E-03 8.86E-04 6.53E-04 4.83E-04 1.2SE-04 

1987 5.35E-06 5.33E-06 5.18E-06 4.73E-06 4.23E-06 1.36E-06 

1988 9.02E-08 8.19E-08 7.17E-08 6.57E-08 5.90E-08 2.31E-08 

1989 1.90E-04 1.75E-04 1.24E-04 7.00E-OS 5.99E-05 1.59E-OS 

1990 1.06E-05 9.69E-06 6.90E-06 3.61E-06 2.SOE-06 8.38E-07 

Sorted results 

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

0.03 2.81E-03 2.62E-03 1.99E-03 1.12E-03 7.80E-04 1.99E-04 

0.06 1.56E-03 1.46E-03 1.22E-03 7.64E-04 5.6SE-04 1.47E-04 

0.10 1.52E-03 1.44E-03 1.18E-03 7.32E-04 5.13E-04 1.34E-04 

0.13 1.15E-03 1.09E-03 8.86E-04 6.53E-04 4.83E-04 1.25E-04 

0.16 9.52E-04 9.10E-04 7.16E-04 4.97E-04 3.65E-04 9.53E-OS 

0.19 8.23E-04 7.74E-04 6.53E-04 4.25E-04 3.05E-04 7.97E-OS 

0.23 5.26E-04 5.04E-04 4.22E-04 2.81E-04 2.04E-04 5.27E-05 

0.26 3.90E-04 3.67E-04 3.01E-04 1.8SE-04 1.39E-04 3.61E-05 

0.29 3.51E-04 3.37E-04 2.84E-04 1.69E-04 1.19E-04 3.06E-OS 

0.32 2.80E-04 2.63E-04 2.06E-04 1.16E-04 8.22E-OS 2.18E-OS 

0.35 2.33E-04 2.16E-04 1.63E-04 1.03E-04 8.07E-OS 2.06E-OS 

0.39 2.20E-04 2.08E-04 1.57E-04 1.00E-04 7.17E-OS 1.84E-OS 

0.42 2.13E-04 2.03E-04 1.57E-04 8.38E-OS 5.99E-OS 1.59E-05 

0.45 1.97E-04 1.84E-04 1.40E-04 8.28E-OS 5.84E-05 1.52E-05 

0.48 1.90E-04 1.7SE-04 1.37E-04 7.85E-05 5.78E-OS 1.49E-05 

0.52 1.82E-04 1.74E-04 1.24E-04 7.00E-05 5.53E-OS 1.43E-05 

0.55 9.67E-05 9.17E-OS 7.44E-05 4.68E-05 3.40E-05 8.82E-06 

0.58 9.54E-05 8.64E-OS 6.36E-OS 3.73E-OS 2.68E-05 6.91E-06 

0.61 8.62E-05 8.11E-05 6.00E-05 3.14E-05 2.19E-OS 6.45E-06 

0.65 2.91E-05 2.78E-OS 2.31E-05 1.67E-05 1.24E-OS 3.40E-06 

0.68 2.62E-05 2.50E-OS 2.02E-05 1.58E-OS 1.20E-OS 3.34E-06 

0.71 1.58E-05 1.53E-OS 1.30E-OS 9.14E-06 8.72E-06 3.16E-06 

0.74 1.06E-05 9.69E-06 6.90E-06 4.73E-06 4.23E-06 1.36E-06 

0.77 5.35E-06 5.33E-06 5.18E-06 3.61E-06 2.99E-06 1.01E-06 

0.81 4.16E-06 3.80E-06 3.63E-06 3.35E-06 2.SOE-06 8.38E-07 

0.84 3.70E-06 3.70E-06 2.66E-06 1.71E-06 1.53E-06 5.36E-07 

0.87 1.92E-06 1.92E-06 1.87E-06 1.44E-06 1.26E-06 4.96E-07 

0.90 8.20E-07 8.15E-07 7.88E-07 7.05E-07 6.28E-07 2.01E-07 

0.94 6.35E-07 5.75E-07 3.92E-07 2.03E-07 1.60E-07 7.31E-08 

0.97 9.02E-08 8.19E-08 7.17E-08 6.57E-08 5.90E-08 2.31E-08 

0.10 1.49E-03 1.40E-03 1.1SE-03 7.24E-04 5.10E-04 1.33E-04 

Average 3.52E-05 

23 
Inputs generated by peS.pl - Novemeber 2006 

Data used for this run: 

Output File: PA_Oxon 

Metfile: w14751.dvf 

PRZM PAturfSTD.txt 

scenario: 

EXAMS 

environ 

ment 

file: 

pond298.exv 

Chemica Coumaphos Oxon 

I Name: 

Descripti Variable Value 

on Name 

Units 

Molecul mwt 346.71 g/mol 

ar 

weight 

Comments 

Henry's henry 1.10E-09 atm-mA3/mol 

Law 

Con st. 

Vapor 

Pressure 

Solubilit 

y 

Kd 

Koc 

Photolys 

is halflife 

Aerobic 

Aquatic 

Metaboli 

sm 

vapr 

sol 

Kd 

Koc 

kdp 

kbacw 

Anaerob kbacs 

ic 

Aquatic 

Metaboli 

sm 

Aerobic asm 

Soil 

Metaboli 

sm 

7.68E-09 torr 

31.6 mg/L 

mg/L 

198 mg/L 

0 .days Half-life 

8.2 days Halfife 

0 days Halfife 

4.1 days Halfife 

24 

of yearly 

averages 
Hydrolys pH 7 0 days Half-life 

is: 

Method: CAM 1 integer See PRZM manual 

lncorpor DE PI em 

ation 

Depth: 

Applicati TAPP 0.0006 kg/ha 

on Rate: 

Applicati APPEFF 1 fraction 

on 

Efficienc 

y: 

Spray DRFT 0 fraction of application rate applied to pond 

Drift 

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

on Date 

Interval interval 10 days Set to 0 or delete line for single app. 

1 

app. rate apprate kg/ha 

1 

Interval interval 10 days Set to 0 or delete line for single app. 

2 

app. rate apprate kg/ha 

2 

Interval interval 10 days Set to 0 or delete line for single app. 

3 

app. rate apprate kg/ha 

3 

Interval interval 10 days Set to 0 or delete line for single app. 

4 

app. rate apprate kg/ha 

4 

Interval interval 10 days Set to 0 or delete line for single app. 

5 

app. rate apprate kg/ha 

5 

Record FILTRA 

17: 

IPSCND 1 

UPTKF 

Record PLVKRT 

18: 

PLDKRT 

FEXTRC 0.5 

Flag for IR EPA 

Index Pond 

Res. Run 

25 
Flag for 

runoff 

calc. 

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

Application 

rate (lb/acre) 

0.310 

PRZM/EXAMS Time Series 

PA_Coumaphos_TS_ SW.csv 

PA_Courraphos ~ Ox on_ TS_SW.csv 

Ground water 

Sample SCIGROW Outputs 

SciGrow version 2.3 

chemical:Coumaphos 

time is 7/29/2013 8:55:26 

Nwnber of 

applications 

Total Use 

(lb/acre/yr) 

Koc 

(ml/g) 

.Soil Aerobic 

metabolism (days) 

1.0 0 . 310 1 . 87E+03 1095 . 0 

groundwater screening cond (ppb) = 3.96E-02 

********************************************************* *************** 

Application 

rate (lb/acre) 

0 . 031 

SciGrow version 2.3 

chemical:Coumaphos Oxen 

time is 7/29/2013 8:56:15 

Nwnber of 

applications 

Total Use 

(lb/acre/yr) 

Koc 

(ml/g) 

Soil Aerobic 

metabolism (days) 

1.0 0.031 1.98E+02 4.1 

groundwater screening cond (ppb) = 1.04E-04 

********************************************************************** 

26 
Sample PRZM-GW Outputs 

[i;l PIUM-(;W (Venoon 1 01) :::- I'X1 ... --.~..._. 

...-s-G...,.., -s--.-.H-......, - Cot19.<...., s........,.o..- .__ ___ _, NQk· Tme...,.. output is delwoed tolhe wM<i'lg drectOIJ Sl>tdied ~ 

I 

... 

HighestOaij>Val""[ppb) ~ 

SmulationAve<ageV-[ppb) ~ 

I SaveGrooh I 

Average Breal<t1YC119> Tmo ) lncomplele 

Post Breal<t!YOI9>A""'IOI 

Tl·~[ppb) fl~ nocmpleee ] 

/O F~Fil! ~- NC.wlna_Celt..,.1110j<t 

/0W<ri< Diectory C adel&~~\ 

North Carolina 

I§ PRZM GW (Vemon 1.01) 1:- !lXI 

... -- ~ ... Pes bade Seenaritt Genotal ------ Scenario: Hori""' Ccnligu<ation I Sum,...y Outi>A 

Nelle. Time,..,.. outi>A is dolivered to the working drectory speclied below 

H9>est0aij>Value[ppb) I 0 0027• I Sin<lationAveroge Value[ppb) Jo.00065S I 

Ave<oge Break.tl'olavgh T me (days) \§. 773 I Tlvo lii1>UII ~ 

Poll Brea!<tlvavgh AvOfage [ppb) lo.000658 I 

0.003 .---------- ---------, 

I Save G<aph I I Ccc>loGrac>h l 

1/0FqFii! Name: NC Q,..,. , 

1/0 Work<1g0rectory. C. \Modell~\ 

NC Cotton 

27