2 

REGISTRATION REVIEW 

ECOLOGICAL RISK ASSESSMENT AND 

EFFECTS DETERMINATION 

Coumaphos 

CAS Number 56-72-4 

US EPA PC CODE 036501 

Prepared by:

Robin Sternberg, Ph.D., Wildlife Biologist 

Faruque Khan, Ph.D., Senior Fate Scientist 

Environmental Risk Branch I 

Reviewed by: 

Meghan Radtke, Ph.D., Biologist 

Stephen Wente, Ph.D., Biologist 

Environmental Risk Branch I 

Environmental Fate and Effects Division 

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

 
3 

Contents

1 Executive Summary ................................................................................................................ 5

2 Problem Formulation .............................................................................................................. 9

2.1 Summary of Activity Since 2008 Problem Formulation .................................................. 9

2.2 Previous Ecological Risk Assessments .......................................................................... 11

2.3 Mode of Action .............................................................................................................. 12

2.4 Use Characteristics ......................................................................................................... 12

2.5 Conceptual Model .......................................................................................................... 15

2.5.1 Risk Hypotheses...................................................................................................... 15

2.5.2 Exposure Pathways of Concern .............................................................................. 15

2.5.3 Stressors of Concern ............................................................................................... 16

3 Fate and Transport Characterization ..................................................................................... 16

4 Exposure Assessment............................................................................................................ 18

4.1 Calculation of Application Rates ................................................................................... 18

4.1.1 Example Calculation: Manure from CAFOs (Concentrated Animal Feeding 

Operation) ............................................................................................................................. 20

4.1.2 Example Calculation: Non-Regulated Small CAFO ≤ 300 cattle .......................... 21

4.1.3 Example Calculation: Cattle Grazing in Rangeland ............................................... 22

4.2 Aquatic Exposure ........................................................................................................... 22

4.2.1 Monitoring Data ...................................................................................................... 24

4.2.2 Aquatic Exposure Modeling: Runoff ...................................................................... 24

4.2.3 Wash-off from the Skin of Treated Livestock That Enter Bodies of Water ........... 29

4.3 Terrestrial Exposure ....................................................................................................... 30

4.3.1 Birds and Mammals ................................................................................................ 30

4.3.2 Terrestrial (Upland and Semi-Aquatic) Plants ........................................................ 36

4.3.3 Honey Bees (In-Hive Use) ...................................................................................... 37

5 Effects Characterization ........................................................................................................ 40

5.1 Effects to Aquatic Organisms ........................................................................................ 40

5.1.1 Freshwater Fish ....................................................................................................... 40

5.1.2 Estuarine/Marine Fish ............................................................................................. 41

5.1.3 Freshwater Invertebrates ......................................................................................... 46

5.1.4 Estuarine/Marine Invertebrates ............................................................................... 46

5.1.5 Benthic (Sediment-Dwelling) Invertebrates ........................................................... 46

5.1.6 Aquatic Plants ......................................................................................................... 47
4 

5.2 Effects to Terrestrial Organisms .................................................................................... 47

5.2.1 Birds ........................................................................................................................ 51

5.2.2 Mammals................................................................................................................. 52

5.2.3 Non-Target Terrestrial Invertebrates ...................................................................... 52

5.2.4 Terrestrial (Upland and Semi-Aquatic) Plants ........................................................ 55

5.3 Incident Database Review .............................................................................................. 56

6 Risk Characterization ............................................................................................................ 58

6.1 Risk Estimation .............................................................................................................. 58

6.1.1 Direct Effects to Aquatic Organisms ...................................................................... 58

6.1.2 Direct Effects to Terrestrial Organisms .................................................................. 64

6.1.3 Probit Slope Dose-Response Analysis of LOC and Acute RQ Values .................. 70

6.2 Risk Description ............................................................................................................. 73

6.2.1 Direct Effects to Aquatic Organisms ...................................................................... 73

6.2.2 Direct Effects to Terrestrial Organisms .................................................................. 76

6.3 Summary of Direct Effects ............................................................................................. 81

6.4 Listed Species Effects Determinations ........................................................................... 86

7 Uncertainties ......................................................................................................................... 87

7.1 Estimates of Exposure .................................................................................................... 87

7.2 Endocrine Disruptor Screening Program (EDSP) .......................................................... 87

8 References ............................................................................................................................. 88

9 Bibliography of Cited MRIDs .............................................................................................. 91

Appendix A: Example PRZM/EXAMS Output ........................................................................... 95

Appendix B: KABAM Analyses .................................................................................................. 99

Appendix C: ECOTOX Literature Search – Papers That Were Accepted ................................. 100

Appendix D: ECOTOX Literature Search – Papers That Were Not Acceptable ....................... 107

 
5 

1 Executive Summary 

The purpose of this screening-level ecological risk assessment is to evaluate potential risks to 

non-target species, both non-listed and federally-listed endangered and threatened species 

(hereafter referred to as non-listed and listed species, respectively) from registered uses of 

coumaphos as part of the Registration Review program1

 pursuant to Section 3(g) of the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

Coumaphos (3-chloro-7-diethoxyphosphinothioyloxy-4-methylcoumarin) is an organophosphate 

insecticide/acaricide used to control flies (face fly, horn fly), ticks, lice, mites (scabies mite) and 

screw worms on livestock (e.g., dairy cattle, horses, sheep, and swine) and swine bedding, and to 

control varroa mites and small hive beetles in bee hives. 

This assessment considers potential exposure to coumaphos as a result of the application of 

coumaphos to livestock and in-hive use of coumaphos. The latter exposure pathway of concern 

is considered only for honey bees. Table 1-1 provides a list of the exposure pathways by taxon 

that are considered in this assessment for the application of coumaphos to livestock. 

Table 2-1. Exposure Pathways by Taxon for Application of Coumaphos to Livestock 

Taxon Exposure Pathways Assessed 

Birds  contact with/ingestion of hair and skin debris from treated cattle and/or 

contaminated soil and feed in and around treatment areas 

 ingestion of contaminated bird carcasses 

 ingestion of food items on land receiving manure from Concentrated Animal 

Feeding Operations (CAFOs) 

 ingestion of contaminated fish 

Mammals  ingestion of contaminated bird carcasses 

 ingestion of food items on land receiving manure from CAFOs 

 ingestion of contaminated fish 

Terrestrial plants*  uptake from CAFO manure applied to land 

 uptake from soil receiving runoff from land to which manure from CAFOs has 

been applied 

Fish, aquatic 

invertebrates, and 

aquatic plants 

 uptake from surface waters receiving runoff from land to which contaminated 

manure has been applied 

 uptake from surface waters receiving runoff from non-regulated small CAFOs 

(i.e., < 300 animals) 

 uptake from surface waters receiving runoff from rangeland where treated 

livestock graze 

 uptake from surface waters into which treated livestock wade (i.e., wash-off from 

treated livestock that enter bodies of water) 

* Given the low application rates calculated for runoff from rangeland where treated livestock graze (see Table 4-6), 

uptake from soil receiving runoff from rangeland where treated livestock graze was not considered to be an exposure 

pathway of consequence. 

A summary of direct effects to listed and non-listed taxa from registered uses of coumaphos is 

provided in Tables 1-2 and 1-3. 

 

1 http://www.epa.gov/oppsrrd1/registration_review/
6 

Table 1-2. Summary of Direct Effects for Aquatic Organisms 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Inciden

Exposure pathways: 

Runoff from land 

to which CAFO 

manure has been 

applied 

Runoff from nonregulated small 

CAFOs (i.e., < 300 

animals) 

Runoff from 

rangeland 

Wash-off from 

treated livestock 

that enter bodies 

of water

Freshwater fish and aquatic-phase amphibians 

Listed No No No No No Non- No Listed No No No No No 

Estuarine/marine fish 

Listed No No No No No Non- No Listed No No No No No 

Freshwater invertebrates 

Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas: Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

Rest of U.S.: No 

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

No 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Estuarine/marine invertebrates 

Listed Yes No 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

No 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

NonListed Yes No No No 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

Benthic (sedimentdwelling) invertebrates 

Listed Yes 

RQs not calculated 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) RQs not calculated 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

Non- Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Aquatic vascular plants 

Listed No No No No No Non- No Listed No No No No No 
7 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Inciden

Exposure pathways: 

Runoff from land 

to which CAFO 

manure has been 

applied 

Runoff from nonregulated small 

CAFOs (i.e., < 300 

animals) 

Runoff from 

rangeland 

Wash-off from 

treated livestock 

that enter bodies 

of water

Aquatic non-vascular plants 

Listed NA 

RQs not calculated No 

NonListed No 

NA = not applicable; no listed aquatic non-vascular plants * Direct or indirect effects to specific listed species have not been definitively determined; further investigation into temporal, geographical, and 

the registered uses and affected taxa is needed before definitive effects determinations can be made. 

Table 1-3. Summary of Direct Effects for Terrestrial Organisms 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Incidents? C

Exposure pathways: 

Hair and skin 

debris from 

treated cattle 

and/or 

contaminated soil 

and feed in and 

around treatment 

areas 

Contaminated 

bird carcasses 

CAFO 

manure 

applied to 

land 

Runoff from 

land to which 

CAFO manure 

has been applied 

Contaminated 

fish 

Birds, reptiles, and terrestrial-phase amphibians 

Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute) 

NA 

Texas, 

Rest of U.S.: 

Yes 

(acute; select 

species) 

Yes 

Recccsibe

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute)

No 
8 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Incidents? C

Exposure pathways: 

Hair and skin 

debris from 

treated cattle 

and/or 

contaminated soil 

and feed in and 

around treatment 

areas 

Contaminated 

bird carcasses 

CAFO 

manure 

applied to 

land 

Runoff from 

land to which 

CAFO manure 

has been applied 

Contaminated 

fish 

Mammals 

Listed Yes 

NA 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute) NA 

No 

No -

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

No No 

Terrestrial (upland and semi-aquatic) plants 

Listed No 

RQs not calculated No 

Ttoto

NonListed No 

Honey bees (in-hive use) 

Listed NA** 

NA Yes T

q

Non- Listed Yes 

NA = not applicable * * Direct or indirect effects to specific listed species have not been definitively determined; further investigation into temporal, geographical, an

the registered uses and affected taxa is needed before definitive effects determinations can be made. ** Not applicable because the analysis for in-hive use only applies to honey bees which are non-listed.
9 

2 Problem Formulation 

The “EFED Ecological Risk Assessment Problem Formulation for Coumaphos Registration 

Review,” which discussed the stressor and the tools and methods with which the Agency 

proposed to assess potential risk, was completed in 2008 (DP 347376; April 28, 2008). In order 

to avoid repetition of material previously provided, that document should be referred to for 

detailed information. 

2.1 Summary of Activity Since 2008 Problem Formulation 

Since the 2008 problem formulation, no new screening-level ecological risk assessments for 

coumaphos were completed. However, the following studies have been submitted and reviewed: 

a Tier II aquatic vascular plant study with Lemna gibba (MRID 48322801); a Tier II aquatic nonvascular plant study with the green alga Pseudokirchneriella subcapitata (MRID 48322802); and 

an adsorption/desorption study for coumaphos and its degradate coumaphos oxon in four soil 

types (MRID 45721401). In addition, an aerobic soil metabolism study with coumaphos oxon in 

two Texas soils was submitted to the Agency (MRID 48705501). The study with L. gibba

yielded a EC50 of >166 μg a.i./L and a NOAEC of 166 μg a.i./L and was classified as 

“supplemental” due a guideline deviation (i.e., a the number of plants per replicate was lower 

than recommended). The study with P. subcapitata was classified as “invalid” because the 

solvent had a stimulatory effect that could have masked the true effects of coumaphos. An 

additional aquatic non-vascular plant study for coumaphos was not requested based on an 

analysis presented in an EFED memo (DP 406398, October 31, 2012; see Section 5.1.6 for 

additional details). The adsorption/desorption study (MRID 45721401) for coumaphos and its 

degradate coumaphos oxon was classified as “partially acceptable” due to the unresolved issue of 

using a biocide as a soil sterilization procedure. The aerobic soil metabolism study (MRID 

48705501) was classified as “supplemental” due to a soil extraction procedure that may not be 

adequate to remove all identifiable residues from soil. 

The 2008 problem formulation indicated that the Registration Review ecological risk assessment 

would estimate risk as a result of exposure from the application of coumaphos to cattle and 

exposure from the application of bioremediated spent dip vat solutions to land. Risk from the 

former exposure pathway would be estimated using registrant-submitted data for estimating 

wash-off from cow hides. 

A 2007 Label Data Report2

 by the Biological and Economic Analysis Division (BEAD) indicates 

that a single label (Co-Ral® Flowable Insecticide; Reg. No. 011556-98) allows for application of 

coumaphos to livestock via dip vat. This label specifies that use is restricted to “employees of 

the U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) 

who are enrolled in the USDA-APHIS cholinesterase monitoring program.” Furthermore, the 

label states that: 

“The Agency requires that spent dip-vat solution be bioremediated, and recommends the 

bioremediation method developed by the USDA. The treated solution must be transferred 

 

2

 Date: September, 2007 
10 

to shallow, concrete-lined evaporation ponds for further degradation. The evaporation 

ponds must be constructed to prevent overflow or flooding during wet seasons and must 

be lined with reinforced concrete. Dried sludge generated in the evaporation ponds must 

not be applied to agricultural land and should be disposed according to solid waste 

disposal regulations established by your Local and/or State Environmental Control 

Agency. Questions concerning the disposal of spent solution should be directed to the 

waste representative at the nearest EPA Regional Office.” 

In the 2008 problem formulation, the Agency requested that stakeholders provide information to 

refine the ecological risk assessment. APHIS responded to the request for “any current 

information pertaining to disposal of bioremediated solution (i.e., dried sludge generated in the 

evaporation ponds” as follows: 

“There are three evaporation ponds used by CFTEP3

 officials in Texas. One evaporation 

pond is located in each of the three following cities: Mission, Eagle Pass, and Laredo. 

Due to the small amount of sediment in the Mission and Eagle Pass evaporation ponds, it 

has not been necessary to dispose of any sediment from those locations. A sample of the 

dried sediment from the evaporation pond in Mission was sent to the National Veterinary 

Services Laboratory (NVSL,) in Ames, Iowa for testing. The test indicated that no 

coumaphos was present. A small amount of dried sediment (approximately 12 feed 

sacks) was cleaned out of the Laredo pit, placed into a sack, and disposed of at an 

approved landfill. In order to support APHIS' belief that the disposal of Co-Ral used in 

the CFTEP does not contribute to water contamination, APHIS would like to take this 

opportunity to point to USDA's PDP monitoring data for finished (treated) or untreated 

water. In 2005 and 2006, no coumaphos was detected in finished water or untreated 

water.” (DP 347373) 

Given that dried sludge generated in evaporation ponds containing bioremediated dip vat 

solution is discarded in a landfill by USDA-APHIS, EFED concludes that exposure via 

application of bioremediated spent dip vat solutions to land is not a complete exposure pathway. 

Therefore, risk as a result of exposure from the application of bioremediated spent dip vat 

solutions to land is not estimated or characterized in the present assessment. 

According to the 2008 problem formulation, 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 Registration Review ecological risk assessment because they do not provide complete routes 

of exposure to surface waters or to the surrounding non-target terrestrial environment. However, 

in a November 1, 2012 memo (DP 393874; November 1, 2012), EFED reviewed the 2008 

problem formulation to determine whether additional pollinator studies were needed to assess the 

potential for risk due to the registered use of coumaphos as an in-hive insecticide to control 

varroa mites and the small hive beetle. 

The EFED memo stated: “There are two scenarios when the safety of a pesticide applied to an 

animal is a factor. In the first scenario, when a pesticide is applied to livestock, such as cattle, 

swine, or poultry, no safety data are required to determine if the pesticide may pose a threat to 

the health of the livestock. The assumption made in the absence of data is that a registrant would 

 

3

 Cattle Fever Tick Eradication Program 
11 

not have a market for a product that is not safe for the livestock it is meant to protect. However, 

residue data are required for meat products of the livestock to ensure that tolerances established 

for the protection of human health are not exceeded. In the second scenario, when a pesticide is 

used as a spot-on product for parasite control on a companion animal, such as a dog or cat, safety 

data are required to determine if the pesticide may pose a threat to the health of the companion 

animal (OCSPP 870.7200).” 

The EFED memo then presented a 3-step analysis to assess the potential for risk to bees from the 

in-hive use of coumaphos. As a result of this three-step analysis, the memo concluded that 

EFED is able to qualitatively assess hazard (toxicity only) to honey bee colonies. Specifically, 

there is a potential for hazard to individuals of honey bee colonies, as well as hive stability, as a 

result of coumaphos use. The memo indicated that EFED may also be able to quantitatively 

characterize risk (integration of toxicity and exposure) in the future Registration Review 

ecological risk assessment using the information described in the memo. Therefore, based on the 

use pattern and exposure scenario of coumaphos, EFED did not recommend requesting any 

further data for the effects of coumaphos on honey bees at that time. Since the writing of the 

memo, EFED has examined the available data and concluded that risk to bees from in-hive use 

of coumaphos in impregnated strips can only be assessed qualitatively due to the lack of data that 

is suitable for a quantitative approach. 

2.2 Previous Ecological Risk Assessments 

No ecological risk assessments for coumaphos have been conducted since the 2008 EFED 

problem formulation (DP 347376; April 28, 2008). The problem formulation presented the 

following ecological risk conclusions based on previous ecological risk assessments4

 conducted 

for coumaphos: 

 Avian risk from acute exposure: Coumaphos is expected to pose acute risk to birds. 

Birds may be subject to primary exposure via ingestion of hair and skin debris from 

treated cattle or secondary exposure via ingestion of birds killed by the pesticide, and 

contaminated with the pesticide. 

 Avian risk from chronic exposure: The Agency concluded that avian reproduction studies 

were not required for coumaphos. Such studies may be required when birds are likely to 

be exposed to a pesticide repeatedly or continuously. According to the 1996 RED 

 

4

 Finalization of Interim Reregistration Eligibility Decisions (IREDs) and Interim Tolerance Reassessment and Risk 

Management Decisions (TREDs) for the Organophosphate Pesticides, and Completion of the Tolerance 

Reassessment and Reregistration Eligibility Process for the Organophosphate Pesticides. July 3 1,2006. EPA 73 

8-R-00- 10. 

EFED Drinking Water and Ecological Risk Review for Coumaphos (036501) IR-4 Use on Beehives. DP 315770. 

May 16, 2006 

Screening Level Aquatic Exposure Assessment for the Use of Coumaphos in the Pacific Northwest and California 

to Treat Cattle via Spray and Vat Dips for the Endangered Species (ES) Consultation Package. DP 303298. June 

6, 2004. 

US EPA Reregistration Eligibility Decision (RED) for Coumaphos. August 1996. EPA 738 R-96-014. 

EFED Review for Coumaphos RED. September 19, 1994. (EFED's environmental fate and ecological effects 

sections for the Cournaphos 1996 RED) 
12 

document's assessment of acute risk, “if there were significant coumaphos exposure to 

birds, they would be killed before chronic effects could occur.” 

 Mammalian risk from acute exposure: Coumaphos is not expected to pose a risk to 

endangered or non-endangered mammals because the limited use pattern of coumaphos, 

i.e., treatment of cattle in confined areas, is not expected to result in significant exposure. 

 Aquatic organism risk: Based on the Agency analysis, coumaphos usage on cattle is 

expected to pose an acute risk to aquatic invertebrates. Coumaphos is not expected to 

pose acute or chronic risks to listed or non-listed fish. 

It should be noted that these risk conclusions were revisited in the present assessment to ensure 

their accuracy in the context of current available data and risk assessment methods. 

2.3 Mode of Action 

Coumaphos (O,O-diethyl O-3-chloro-4-methyl-2-oxo-21-H benzopyran-7-yl phosphorothioate) 

is an insecticide/acaricide that belongs to the organophosphate class of pesticides. The toxic 

mode of action of coumaphos is the inhibition of acetyl cholinesterase resulting in repeated nerve 

firing due to build up of acetylcholine, hyperexcitation, and eventually death. 

2.4 Use Characteristics 

Coumaphos was first registered in the United States in 1958 for use as an insecticide. A dust 

formulation, the first end-use product, was registered the following year for the control of insects 

on cattle. Currently, coumaphos is registered for the control of flies (face fly, horn fly), ticks, 

lice, mites (scabies mite) and screw worms on livestock (e.g., dairy cattle, horses, sheep, and 

swine) and swine bedding and to control varroa mites and small hive beetles in bee hives. 

Coumaphos is formulated as a dust, emulsifiable concentrate, and flowable concentrate and is 

applied directly to livestock via dip vat, low and high-pressure hand wand, back rubber/oiler, 

mechanical duster, dust bag or shaker can. 

This Registration Review ecological risk assessment used coumaphos application information as 

presented in the 2008 EFED problem formulation (DP 347376; April 28, 2008) and associated 

label data report (Label Use Information System report; LUIS) dated September 13, 2007 as well 

as additional information provided by BEAD (e.g., volume of solution mixed per animal to 

convert rate in lb a.i./gal as specified on some labels to lb a.i./animal). There have been no new 

uses of coumaphos registered since the 2008 EFED problem formulation. 

Based on usage information presented in the 2008 EFED problem formulation, the largest 

livestock use of coumaphos is for cattle (59,000 lb a.i./yr for cattle vs. 12,000 lb a.i./yr for other 

livestock; DP 347376, April 28, 2008). Therefore, this assessment was conducted using 

application rates for cattle. Maximum application rates (single and annual), minimum 

application intervals, and application methods/equipment for cattle are provided in Table 2-1. It 

should be noted that labels for coumaphos typically do not specify a maximum annual 

application rate. Therefore, maximum annual application rates were calculated for cattle using 

the maximum single application rate and annual number of applications. 
13 

The maximum single application rate (i.e., 0.027 lb a.i./animal for dip vat5

) and the maximum 

annual application rate (i.e., 0.063 lb a.i./animal for spray6

) for cattle are for the end-use product 

Co-Ral® Flowable Insecticide (EPA Reg. no. 11556-98). Use of this product is restricted to 

employees of the USDA-APHIS who are enrolled in the USDA-APHIS cholinesterase monitoring 

program. The USDA’s Cattle Fever Tick Eradication Program (CFTEP) uses this product solely 

in Texas. As a result, these maximum application rates were used to assess risk to non-target 

species in Texas only. The next highest maximum single application rate (i.e., 0.01 lb a.i./A for 

dust or spray7

) and maximum annual application rate for cattle (i.e., 0.05 lb a.i./animal for back 

rubbers8

) were used to assess risk to non-target species in the rest of the United States.

 

5

 2 applications @ 0.027 lb a.i./animal = 0.054 lb a.i./animal/yr for dip vat 

6

 3 applications @ 0.021 lb a.i./animal = 0.063 lb a.i./animal/yr for spray 

7

 3 applications @ 0.01 lb a.i./animal = 0.03 lb a.i./animal/yr for spray or dust 

8

 6 applications @ 0.00829 lb a.i./animal = 0.05 lb a.i./animal/yr for back rubbers 
14 

Table 2-1. Application Information for Registered Uses of Coumaphos: Cattlea,b,c 

Use Application 

Method/ Equipment 

Form. (% a.i.) 

Maximum Single 

Application Rate 

Annual 

Number of 

Applications

Minimum 

Application 

Interval 

(Days)

Maximum 

Annual 

Application 

Rated

(lb a.i./animal) 

(lb a.i./ 

animal) 

(lb a.i./

gal) 

Beef/range/ feeder cattle; dairy cattle 

Back rubbers EC (11.6) 0.00829 (avg.; est.) 0.0762 3.5 (avg.) NS or AS 0.029 -- Back rubbers EC (6.2) 0.00829 (avg.; est.) 0.0385 6 or NS 10 or NS 0.050 Represents m

rate for the U.Texas

Dip vat FC (42) 0.027 (est.) 0.0255e 2 10 0.054 

EPA Reg No. employees of Represents mrate for Texas 

Dust Dust (1) 0.01 3 (avg.) NS 0.03

Represents mrate for the U.Texas 

Dust Dust (1) 0.0013 3 (avg.) 10 or 14 0.0039 -- Dust Dust (1) 0.000625 3 (avg.) 1 0.0019 -- Spray FC (42) 0.021 (est.) 0.021 3 (avg.) 10 0.063 

EPA Reg No. employees of Represents mrate for Texas 

Spray EC (6.2) 0.01 (est.) 0.01 3 (avg.) 10 0.03 Represents m

rate for the U.Texas 

Spray EC (11.6) 0.00978 (est.) 0.00978 3 (avg.) AS 0.029 -- Ear Tag IM (20) 0.00625 3 (avg.) NS 0.019 -- 

AS = as needed; avg. = average; est. = estimated (by BEAD); NS = not specified; EM = emulsifiable concentrate; FC = flowable conce

formulation; IM = impregnated material; Max. = Maximum; Min. = Minimum; NA = not applicable; RTU = ready to use 

a label data report (Label Use Information System report; LUIS) dated September 13, 2007 b application information for maximum single and annual rates in BOLD c estimated/average values provided by BEAD d not specified on label; calculated based on maximum single application rate and maximum annual number of applications e 0.306% suspension 
15 

2.5 Conceptual Model 

2.5.1 Risk Hypotheses 

As stated in the 2008 EFED problem formulation (DP 347376; April 28, 2008), this Registration 

Review ecological risk assessment tests the following risk hypothesis: 

Non-target terrestrial and aquatic animals and plants are at risk of direct and indirect effects 

resulting from labeled uses or land disposal of coumaphos. 

2.5.2 Exposure Pathways of Concern 

This Registration Review ecological risk assessment considers potential exposure to coumaphos 

as a result of: 

 the application of coumaphos to livestock and 

 in-hive use of coumaphos. 

The latter exposure pathway of concern is considered only for honey bees. Potential exposure 

from the application of bioremediated spent dip vat solutions to land is not considered in the 

assessment because it is not a complete exposure pathway (see Section 2.1 for rationale). 

The 2008 EFED problem formulation (DP 347376; April 28, 2008) provided a general 

conceptual model of the fate/transport and effects of coumaphos in the environment for the 

application of coumaphos to livestock. Since coumaphos has not been detected in groundwater, 

exposure via irrigation water containing coumaphos was not considered in this assessment. 

Table 2-2 provides a list of the exposure pathways that are considered in this assessment for the 

application of coumaphos to livestock. 

Table 2-2. Exposure Pathways by Taxon for Application of Coumaphos to Livestock 

Taxon Exposure Pathways Assessed 

Birds  contact with/ingestion of hair and skin debris from treated cattle and/or 

contaminated soil and feed in and around treatment areas 

 ingestion of contaminated bird carcasses 

 ingestion of food items on land receiving manure from Concentrated Animal 

Feeding Operations (CAFOs) 

 ingestion of contaminated fish 

Mammals  ingestion of contaminated bird carcasses 

 ingestion of food items on land receiving manure from CAFOs 

 ingestion of contaminated fish 

Terrestrial plants*  uptake from CAFO manure applied to land 

 uptake from soil receiving runoff from land to which manure from CAFOs has 

been applied 

Fish, aquatic 

invertebrates, and 

aquatic plants 

 uptake from surface waters receiving runoff from land to which contaminated 

manure has been applied 

 uptake from surface waters receiving runoff from non-regulated small CAFOs 

(i.e., < 300 animals) 

 uptake from surface waters receiving runoff from rangeland where treated 

livestock graze 

 uptake from surface waters into which treated livestock wade (i.e., wash-off from 

treated livestock that enter bodies of water) 
16 

* Given the low application rates calculated for runoff from rangeland where treated livestock graze (see Table 4-6), 

uptake from soil receiving runoff from rangeland where treated livestock graze was not considered to be an exposure 

pathway of consequence. 

2.5.3 Stressors of Concern 

2.5.3.1 Terrestrial Assessment 

The stressor of concern for the terrestrial portion of this ecological risk assessment is 

coumaphos. 

2.5.3.2 Aquatic Assessment 

Coumaphoxon was detected in an aqueous photodegradation study at a maximum of 10.2% of 

applied chemical (MRIDs 42764101 and 43103901). Therefore, the stressors of concern for the 

aquatic portion of this assessment are coumaphos and its oxygen analog coumaphoxon (O,Odiethyl O-3-chloro-4-methyl-2-oxo-2-H-1-benzopyran-7-yl phosphate). 

3 Fate and Transport Characterization 

Coumaphos (O-[3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl] O,O-diethyl phosphorothioate) 

is an organophosphate insecticide/acaricide. Physical, chemical and environmental fate 

properties of coumaphos are presented in Table 3-1. Coumaphos has a relatively low vapor 

pressure (1.0 × 10-7 mm Hg) and Henry’s Law constant (4.62 × 10-9 atm·m3

/mol), which suggest 

that volatilization is not expected to be a major route of dissipation from soil and water. A 

limited environmental fate database for coumaphos indicates that it is persistent (DT50 of >1 year 

in aerobic soil) and slightly mobile to hardly mobile (Kfoc of 1874 to 10297 L/Kg) in soil 

according to FAO classification of mobility in soil (FAO, 2000). Hydrolysis is also not a 

significant route of dissipation for coumaphos. In two field dissipation studies where coumaphos 

was applied at 300 ppm with and without incorporation, the half-life of coumaphos was 

determined to be 118 and 185 days. Although the soil was not sampled deep enough to define 

the extent of leaching, samples taken at the 6- to 12-inch depth (the deepest layer sampled) 

contained between 25-375 ppm at 32 weeks and 5-69 ppm at 52 weeks post-treatment. The 

terrestrial field dissipation studies indicate that coumaphos is relatively persistent, as was also 

indicated by the aerobic soil metabolism study. 

The major pathway of coumaphos degradation appears to be photodegradation in water (DT50 of

33 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 for coumaphoxon (Table 3-2) suggest that it is not a persistent compound in the 

terrestrial environment (aerobic soil metabolism DT50 of 0.49 to 2.27 days) and that it is mobile 

to moderately mobile (Kfoc of 767 to 5810 L/Kg) in soil according to FAO classification of 

mobility in soil (FAO, 2000). Total coumaphos residues accumulated in bluegill sunfish with a 

maximum bioconcentration factor of 541X in whole fish during 30 days of exposure to 

coumaphos. Accumulated coumaphos residues were depurated rapidly, with 95% elimination 

after 1 day in untreated water. 
17 

Table 3-1. Physical, Chemical and Environmental Fate Properties of Coumaphos 

Parameter Value Source 

Common name Coumaphos 

USEPA, 2007 

Chemical name 3-chloro-7- diethoxyphosphinothioyloxy-4-

methylcoumarin 

CAS # 56-72-4 

CAS Name O-(3-chloro-4-methyl-2-oxo-2H-1-

benzopyran-7-yl) O,O-diethyl 

phosphorothioate 

Empirical formula C14H16ClO5PS 

Structure 

Molecular mass 362.5 USEPA, 2007 

Water solubility (20C) 20 mg/L USEPA, 2007 

Vapor pressure (20C) 1.0E-07mm Hg USEPA, 2007 

Henry’s Law Constant 2.62E-09 atm m3/mol Estimated 

Octanol/water partition coefficient (Log Kow) 4.3 TOXNET 

Hydrolysis (DT50) Stable at pH 5,7 and 9 

USEPA, 1993a 

MRIDs 

00150197 

00159928 

Direct Aqueous Photolysis (DT50) 1.38 days MRID 42764101 

MRID 43103901 

Soil Photolysis 24 days 

40 days 

MRID 42920301 

MRID 43167401 

Aerobic Soil Metabolism (DT50) Stablea MRID 40518701 

Anaerobic Soil Metabolism (DT50) No Data --- 

Aerobic Aquatic Metabolism (DT50) No Data --- 

Soil Partition Coefficient (Kf) 

Soil Partition Coefficient (Kfoc) 

57.3 L kg-1 for Sand

26.0 L kg-1 for Sandy Clay Loam

65.2 L kg-1 for Clay Loam

65.9 L kg-1 for Clay Loam 

5257 L kg o.c.-1 for Sand

6190 L kg o.c.-1 for Sandy Clay Loam

1874 L kg o.c.-1 for Clay Loam

10297 L kg o.c.-1 for Clay Loam 

MRID 45721401 

Mobility-Leaching 

Column Study 

(Aged sample) 

Immobile 

MRID 00163806 

Terrestrial Field Dissipation (DT50) 185 days (in the upper 6 inches of soil) MRID 00115166 

Bioconcentration (BCFs) 

541X Whole Fish MRIDs 

00115168 and 

00150619 
18 

a

 Since the revised DT50 of 2752 days (calculated using the NAFTA Guidance, USEPA, 2012a) is well beyond the 

duration of the study (365 days), the aerobic soil half-life is considered as stable. 

Table 3-2. Physical, Chemical and Environmental Fate Properties of Coumaphoxon 

Parameter Value Source 

Chemical Structure 

 MRID 48705501 

Chemical Name Coumaphos Oxon MRID 48705501 

CAS Name O-(3-Chloro-4-methyl-2-oxo-2H-1-

benzopyran-7-yl)O,O-diethyl phosphate 

MRID 48705501 

IUPAC 3-Chloro-4-methyl-2-oxo-2H-1-benzopyran7-yl diethyl phosphate 

MRID 48705501 

Molecular Weight 346.71 EPISUITE 4.1 

Solubility (25° C) 31.61 mg/L (Based on Log KOW Method) 

210.46 mg/L (Fragment Method) 

EPISUITE 4.1 

Vapor pressure (25C) 7.68 x 10-8 mm Hg EPISUITE 4.1 

Henry’s Law Constant 1.10 x 10-9atm m3/mol EPISUITE 4.1 

Octanol/water partition coefficient (Log Kow) 2.71 EPISUITE 4.1 

Soil Partition Coefficient (Kf)

Soil Partition Coefficient (Kfoc) 

11.4 L-1 kg for Sand

24.4 L kg-1 for Sandy Clay Loam

26.7 L-1 kg for Clay Loam

26.0 L-1 kg for Clay Loam 

1046 L kg o.c.-1 for Sand

5810 L kg o.c.-1 for Sandy Clay Loam

767 L kg o.c.-1 for Clay Loam

4063 L kg o.c.-1 for Clay Loam 

MRID 45721401a

198.4 L kg EPISUITE 

Aerobic soil Metabolism (DT50) Silt soil 0.49 days 

Loamy Sand soil 2.27 days 

MRID 48705501 

a

 Soil partition coefficient values reported in MRID 45721401 are problematic. In a recent study, there was a 

substantial degradation (0 – 92%) of the coumaphoxon during the 24-hr equilibration period (personal 

communication-via email on 6/24/2013) possibly due to hydrolysis.

4 Exposure Assessment 

4.1 Calculation of Application Rates 

During a rain event, a certain fraction of coumaphos wash-off from treated cattle can be 

potentially adsorbed into manure as well as transported as runoff from CAFOs and 

pasture/rangeland. Estimated exposure concentrations (EECs) from runoff and wash-off were 

calculated for Texas and the rest of the U.S. using maximum application rates for cattle (see 

Section 2.4 for application rates and rationale) as well as data from acceptable registrantsubmitted studies quantifying the fraction of coumaphos that becomes available for exposure 

after soaking a cow hide in water (i.e., wash-off fraction; Table 4-1). 
19 

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, 2, or 4 hours. Results of these studies indicate that 

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

4-1) but not affected by soaking time (data not shown). Although not the most conservative, 

wash-off fractions for the 24-hour drying time were used in this assessment because they 

represent a reasonable time frame after application for a treated cow to be caught in a rainstorm 

or enter a body of water. 

Table 4-1. Percent Wash-Off for Different Formulations of Coumaphos at Different Drying 

Times (MRIDs 42512601 and 42512602) 

Formulation 

(%) 

Drying Time 

(hrs) 

Wash-Off 

Fraction 

Comment 

Emulsifiable 

powder/concentrate 

(11.6) 

0.5 0.116 Represents formulation associated with maximum 

application rates for the U.S. with the exception of Texas 

(back rubbers and spray) 

3 0.046 

24 0.027 

Wettable 

powder/flowable 

concentrate (25) 

0.5 0.38 Represents formulation associated with maximum 

3 0.21 application rates for Texas (dip vat and spray) 

24 0.02 

To accurately characterize the potential environmental exposure pathways, selecting the 

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

Several scenarios were considered to estimate the application rate for coumaphos and potential 

exposure to coumaphos for terrestrial and aquatic environments. The following scenarios and 

example calculations of application rates are based on spray (Texas) or back rubber (rest of the 

U.S.) application on cattle. Table 4-2 provides application rates for various scenarios. 

Table 4-2. Estimated Coumaphos Application Rates for Various Scenariosa 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Maximum Single 

Application Rate 

(lb/A) 

Number of 

Applications/

Year 

Maximum 

Annual 

Application Rate 

(lb/A) 

Texas: Spray Application (42% flowable concentrate) 

CAFO manure applied to landb No incorporation of manure into soil 

0.02 0.015 1c 0.015 

Incorporation of manure into soil within a day 

0.02 0.009 1c 0.009 

Runoff from small non-regulated CAFO 0.02 0.008 12d 0.096 

Runoff from range land 0.02 0.00013 3 0.0004 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration) 

CAFO manure applied to landb No incorporation of manure into soil 

0.027 0.0092 1c 0.0092 

Incorporation of manure into soil within a day 

0.027 0.0051 1c 0.0051 

Runoff from small non-regulated CAFO 0.027 0.0050 12d 0.0603 

Runoff from range land 0.027 0.0001 3 0.0003 

AU = animal unit 

a

 Sample calculations provided in Sections 4.1.1 to 4.1.3
20 

b Application rate of coumaphos depends on nutrient management and application method of manure. 

c Application rate can be split based on total nitrogen (TN) requirement during the growing season. 

d

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

http://www.epa.gov/agriculture/ag101/beefproducts.html 

4.1.1 Example Calculation: Manure from CAFOs (Concentrated Animal 

Feeding Operation) 

Manure used as a soil amendment/organic fertilizer could be a potential source for pesticides that 

are embedded in it from wash-off from treated livestock. Since coumaphos is stable in soil, 

degradation was not considered. 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)/year 

DM = 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 = (A x F x S x W x PA) lb a.i./AU/year 

Where: 

A = application rate: 0.021 lb/AU for spray application (Table 2-1) 

F = frequency of application: 3/AU/year (Table 2-1) 

S = # of stocking/year: 4 (Based on 90-120 days stocking period for cattle in feedlot9) 

W = wash-off fraction: 0.02 (Texas; coumaphos formulations restricted to APHIS) or 

0.027 (for non-restricted coumaphos formulations; rest of the U.S.) (MRIDs 42512601 

and 42512602) 

PA = potential fraction of coumaphos washed off of cattle during a rain event that can 

come into contact with and adsorb to manure: 0.36 (assumed based on EPISUITE 

estimate for adsorption into sludge) 

Sample calculation is based on Co-Ral® Flowable Insecticide: 

AM = (0.021 x 3 x 4 x 0.02 x 0.36) = 0.0018 a.i. lb/AU 

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

(0.0018 lb a.i./1.55 ton manure) = 0.0012 lbs a.i./ton dry manure 

Step 4: Total nitrogen production (TN) per animal (lbs TN/AU/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) 

 

9 http://www.epa.gov/agriculture/ag101/beefproducts.html
21 

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

2008). The range of N retention varies from 40 to 60 for arid region and 55 to 70 in 

humid region. 

V= Fraction of N loss due to volatilization: 0.1 (based on next day incorporation into soil 

after application in warm wet soil condition) to 0.5 (based on no incorporation for 

seven days into soil) (Table 11.6, USDA, 2006). The range of volatility loss varies 

from 50 percent in warn dry soil to 10 percent in cool wet soil. In addition, volatility 

loss may also depend on method of manure application (i.e. 5% and 25% 

volatilization loss from injection and sprinkling methods respectively. Since there is 

an inverse relationship between volatilization loss and application rate of manure, 

the highest and lowest volatilization rate was considered to calculate application rate 

of coumaphos. 

D = 365 of days /year 

Sample calculation: 

TN = (0.34 x 0.5 x 0.5 x 365) = 31 lbs TN in manure/AU/year [For no incorporation for 

seven days under warm dry soil scenario] 

Step 5: Total N in manure (lb/ton manure) 

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

Step 6: Application rate of manure (ton/acre) 

In general, the application rate of manure is based on TN recommendation for crop types. For 

example, 250 lb TN/acre per year requires for growing warm season perennial grass in Texas10. 

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 (lb/acre)

(0.0012 lbs a.i/ton) x (12.5 tons manure/acre) = 0.015 lbs a.i./acre

Therefore, the application rate of 0.015 lbs a.i/A is based on 2% coumaphos wash-off from 

treated cattle. 

4.1.2 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: 

 

10 Stichles and McFarland, http://agrilifeextension.tamu.edu/
22 

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 feedlot11) 

C = # of AU in feedlot: 300 (Maximum cattle density in non-regulated CAFOs). The 

amount of pen space per animal (stocking density) depends upon climate and 

whether the lots are paved (50 to 75 ft2

/animal) or earthen (250 to 500 ft2/animal). 

Others report stocking densities to range between 150 to 300 ft2

/animal. 

W = wash-off fraction: 0.02 (Texas) or 0.027 (rest of the U.S.) (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 100 cattle/acre; Murphy and Harner, 2006).

Sample calculation: 

AR = (0.021 x 3 x 4 x 300 x 0.02 x 0.64 x 0.1) = 0.0096 lb a.i./A/yr 

4.1.3 Example Calculation: Cattle Grazing in Rangeland 

Runoff of washed-off coumaphos from treated cattle could be a 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) 

Where: 

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

F = frequency of application: 3 (spray application) 

C = # of AU in pasture/land: 0.3 was based on 800 lbs cattle (Pratt and Rasmaussan, 

2001). There is an inverse relationship between weight of cattle and number of AU 

in pasture/land. Numbers of AU on pasture land also depends on the size of cattle 

and forage production. 

W = wash-off fraction: 0.02 (Texas) or 0.027 (rest of the U.S.) (MRIDs 42512601 and 

42512602) 

Sample calculation: 

AR = (0.021 x 3 x 0.3 x 0.02) = 0.0004 lb/A 

4.2 Aquatic Exposure 

Exposure of aquatic organisms to coumaphos could occur as a result of: 

 

11 http://www.epa.gov/agriculture/ag101/beefproducts.html
23 

 uptake from surface waters receiving runoff from land to which contaminated manure has 

been applied; 

 uptake from surface waters receiving runoff from small CAFOs (i.e., < 300 animals); 

 uptake from surface waters receiving runoff from rangeland where treated livestock 

graze; and 

 uptake from surface waters into which treated livestock wade (i.e., wash-off from treated 

livestock entering bodies of water). 

As stated in the problem formulation, the stressors of concern for aquatic exposure are 

coumaphos and its oxygen analog coumaphoxon. There are no data available for the toxicity of 

coumaphoxon to aquatic organisms. However, a comparative acute toxicity study by Tsuda et al. 

(1997) with organophosphate insecticides – diazinon, malathion, fenitrothion, and EPN) and 

their oxygen analogs – diazinon oxon, malaoxon, fenitrothion oxon, and EPN oxon, respectively 

– generally indicates that the oxidation product is more toxic than the parent to fish (Table 4-3). 

In contrast, enzymatic conversion to the oxon dominates hydrolysis of any of the ester linkages 

in insects suggesting that the oxon and parent are equally toxic to these organisms (Fest and 

Schmidt, 1973). Therefore, the acute toxicity of coumaphos was assumed to be equivalent to the 

acute toxicity of its oxidation product for aquatic invertebrates. Equivalent toxicity of parent and 

oxidation product was also assumed for aquatic plants due to the lack of toxicity data. As a 

result, different approaches were taken to calculate aquatic acute EECs for fish and aquatic 

invertebrates and plants. For fish, a toxic equivalency (TEQ) approach was taken using the 

average toxic equivalency factor calculated for the four organophosphate insecticides tested by 

Tsuda et al. (1997) (i.e., 7.25; see Table 4-3) since all the data came from the same laboratory, 

thereby eliminating inter-laboratory variability. The equations for the TEQ approach are 

provided in Table 4-4. Specifically, surface water peak EECs for coumaphos were modeled via 

PRZM/EXAMS and then adjusted for formation and toxicity of the oxidation product to yield a 

parent equivalent peak EEC (parent coumaphos + degradate coumaphoxon). For aquatic 

invertebrates and plants, the total toxic equivalent residue (TTER) approach, which is similar to 

the total toxic residue approach, was taken using the equation in Table 4-4 which yields peak 

EECs (parent coumaphos + degradate coumaphoxon) that are equal to the surface water peak 

EECs for coumaphos modeled via PRZM/EXAMS. 

Since comparative chronic toxicity studies are not available for parent organophosphate 

insecticides and their oxidation products, a TTER approach was used for fish and aquatic 

invertebrates using the equation in Table 4-4 which yields total chronic EECs that are equal to 

surface water chronic EECs for coumaphos modeled via PRZM/EXAMS. 

Table 4-3. Calculation of Toxic Equivalency Factors (TEQs) for Four Organophosphate 

Insecticides 

Parent (MW) 

Oxidation Product (MW) 

48-hr LC50a TEQ 

Parent 48-hr LC50 (μmol/L): 

Oxidation Product LC50 (μmol/L) 

Parent Oxidation Product 

mg/L μmol/L mg/L μmol/L 

Diazinon (304.35) 

Diazinon oxon (288.28) 4.4 14.46 0.22 0.76 18.94 

Malathion (330.4) 

 Malaoxon (314.29) 1.8 5.45 0.28 0.89 6.12 
24 

Parent (MW) 

Oxidation Product (MW) 

48-hr LC50a TEQ 

Parent 48-hr LC50 (μmol/L): 

Oxidation Product LC50 (μmol/L) 

Parent Oxidation Product 

mg/L μmol/L mg/L μmol/L 

Fenitrothion (227.23) 

Fenitrothion oxon 

(261.17) 

3.5 12.62 6.8 26.04 0.48 

EPN (323.3) 

EPN oxon (307.24) 4.4 1.79 0.16 0.52 3.44 

MW = molecular weight (g/mol) 

a based on data from Tsuda et al., 1997 Average 7.25 

Table 4-4. Equations for Calculating Aquatic Total Estimated Environmental 

Concentrations (EECs) and Risk Quotients (RQs) 

Exposure 

Duration 

Taxon Approach EEC(parent+oxon) Acute RQ 

Acute Fish Toxic 

equivalency 

= (% formed(parent)*Peak EEC(parent)*TEQ(parent)) + 

(% formed(oxon)*Peak EEC(parent)*TEQ(oxon)) 

= (0.9*Peak EEC(parent)*1) + (0.1*Peak EEC(parent)*7.25) 

Peak EEC(parent+oxon)/ 

Most sensitive LC50(parent)

Aquatic 

invertebrates 

and plants 

Total toxic 

equivalent 

residues 

(% formed(parent)*Peak EEC(parent)) + 

 (% formed(oxon)*Peak EEC(parent)) 

= (0.9*Peak EEC(parent)) + (0.1*Peak EEC(parent)) 

= Peak EEC(parent)

Peak EEC(parent)/ 

Most sensitive endpoint(parent)

Chronic Fish and 

aquatic 

invertebrates 

Total toxic 

equivalent 

residues 

(% formed(parent) *Chronic EEC(parent)) + 

 (% formed(oxon) *Chronic EEC(parent)) 

= (0.9*Chronic EEC(parent)) + (0.1*Chronic EEC(parent)) 

= Chronic EEC(parent)

Chronic EEC(parent)/ 

Most sensitive endpoint(parent)

% formed(oxon) = % formed in the aqueous photodegradation study = 0.1 

% formed(parent) = 1- (% formed(oxon)) 

Peak EEC(parent) = Peak EEC for coumaphos from PRZM/EXAMS 

Chronic EEC(parent) = 21-day or 60-day EEC for coumaphos from PRZM/EXAMS for aquatic invertebrates and fish, 

respectively 

TEQ(parent) = 1

TEQ(oxon) = 7.25 (from Table 4-3)

4.2.1 Monitoring Data 

Coumaphos is not included as one of the analytes monitored in the U.S. surface and groundwater 

under the USGS’s National Water Quality Assessment (NAWQA) program. Monitoring data for 

surface water, groundwater and sediment from the California Department of Pesticide Regulation 

(CDPR) were searched on September 9, 2013, and all data with analysis for coumaphos were 

extracted. No detection was reported in surface water and groundwater, and coumaphos was not 

monitored in sediment (http://www.cdpr.ca.gov/docs/emon/ehap.htm). 

4.2.2 Aquatic Exposure Modeling: Runoff 

Screening-level surface water exposures for runoff were conducted for coumaphos use on cattle. 

Modeled application rates represent the application rate estimates based on wash-off fractions 

from treated cattle (Table 4-1). Table 4-2 provides various application rates used for assessing 

exposure via runoff. Wash-off fractions for the 24-hour drying time were used in the aquatic 

exposure assessment because they represent a reasonable time frame after application for a 

treated cow to be caught in a rainstorm or enter a body of water. 
25 

The Pesticide Root Zone Model, (PRZM) and the Exposure Analysis Modeling System 

(EXAMS) were used in tandem to generate aquatic estimated environmental concentrations 

(EECs) for parent coumaphos. PRZM (3.12.2 dated May 12, 2005) simulates fate and transport 

on the agricultural/range land whereas EXAMS (2.98.04.06, dated April 25, 2005) simulates the 

fate and resulting daily concentrations in the water body. Simulations are carried out with the 

linkage program shell, PE5V01.pl (dated November 15, 2006), which incorporates the standard 

non-agricultural scenarios developed by EFED. Simulations are run for multiple (usually 30) 

years, and the EECs represent peak values that are expected once every ten years based on the 

thirty years of daily values generated during the simulation. Additional information on these 

models can be found at: http://www.epa.gov/oppefed1/models/water /index.htm. 

Aquatic exposure is estimated for the maximum application pattern to a 10-ha field bordering a 

1-ha pond, 2-m deep (20,000 m3

), with no outlet. Exposure estimates generated using this 

standard pond are intended to represent a wide variety of vulnerable water bodies that occur at 

the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, man-made 

and natural ponds, and intermittent and first-order streams. As a group, there are factors that 

make these water bodies more or less vulnerable than the standard surrogate pond. Static water 

bodies that have larger ratios of pesticide-treated drainage area to water body volume would be 

expected to have higher peak EECs than the standard pond. These water bodies will be either 

smaller in size or have large drainage areas. Smaller water bodies have limited storage capacity 

and thus may overflow and carry pesticide in the discharge, whereas the standard pond has no 

discharge. Headwater streams can also have peak concentrations higher than the standard pond, 

but they likely persist for only short periods of time and are then carried and dissipated 

downstream. Estimates of coumaphos exposure via runoff from the application of treated 

manure and CAFOs to agricultural fields are also highly uncertain. 

Inputs for PRZM/EXAMS are provided in Table 4-5. EECs for surface water (water column) 

are provided in Table 4-6. Pore water concentrations were additionally modeled for the scenario 

that yielded the most conservative surface water EECs for each runoff exposure pathway (i.e., 

Range BSS for rangeland; and PA turf for manure and non-regulated small CAFOs) and are 

provided in Table 4-7. PRZM/EXAMS modeling output of EECs for an example scenario (PA 

Turf) is provided in Appendix A. 

Table 4-5. PRZM/EXAMS Input Parameters for Coumaphos 

Parameter Input Value Source Comment 

Use Site Pasturea

 

 FLTurf 

 BSS Turfb

 PA Turf 

Rangeland

 BSS Rangeland2

--- Assumed coumaphos treated 

animals grazing on pasture 

or rangeland 

Application Date (DD-MM) Manure: 15 -10 

CAFO Run off: 15- 01 

Pasture Runoff: 15-04 

 Fall application 

Assumed four stocking/year 

Spring for grazing 

Application Rate Table 4-2 See calculation (Section 

4.1) 

Number of applications per 

year 

1 to 12 Table 4-2 Number of application and 

application frequency based 
26 

Parameter Input Value Source Comment 

Application interval (days) 10 Table 4-2 on either manure or runoff 

scenarios 

Application method Hand-held spray or dip vat 

method 

Label directions --- 

CAM 1 --- Surface application of 

manure 

1 -- Assumed for wash-off from 

animal hide 

4 -- Incorporation of manure to a 

depth of 8 inches (20.3 cm)c

Hydrolysis (t1/2) 0 MRID 

46902201 

Stable 

Spray drift fraction Not applicable --- --- 

Aerobic soil metabolism (t1/2) 0 day (stable) MRID 

40518701 

Aerobic aquatic metabolism 

(t1/2) 

0 day (stable) No Data Input Parameter Guidance 

(USEPA, 2009) 

Anaerobic aquatic 

metabolism (t1/2) 

0 day No Data Input Parameter Guidance 

(USEPA, 2009) 

Aquatic photolysis (t1/2) 1.38 days MRID 

42764101 

MRID 

43103901 

--- 

Vapor pressure 1. 0E-07 (mmHg) US EPA, 2007 --- 

Solubility in water 

(pH 7, 20 °C) 

20 mg/L 

Molecular weight 362.78 g/mole 

Henry’s Law constant (20 °C) 2.62E-09 atm.m3 /mol Estimatedd

Partition coefficient Koc 5904 mL/g MRID 

46808411 

Represents average Koc for 4 

soils a

 Turf scenarios were used as surrogate scenarios for pasture land 

b

 Major use of coumaphos is in dip vats by USDA (APHIS) on the Texas-Mexico border for cattle coming into 

the United States from Mexico in the tick quarantine zone in Texas. Since no PRZM/EXAMS standard scenario 

is available for Texas, BSS Turf and BSS Rangeland were used as surrogate scenarios for coumaphos 

c http://ohioline.osu.edu/agf-fact/0208.html

d http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm
27 

Table 4-6. Estimated Environmental Concentrations (EECs) of Coumaphos in Surface Water from RunofApplication Scenarios 

PRZM/ EXAMS Scenario 

Sources of a.i. from Application Scenario 

Wash-Off 

Fraction 

Peak EEC(parent)

 (μg/L) 

 (Coumaphos) 

Peak EEC(parent+oxon)* (μg/L) 

(Coumaphos + Coumaphoxon) 

Chronic 

(Couma

Fish Aquatic Inverts 

and Plants 

21-da

(Aquatic I

Texas: Spray Application (42% flowable concentrate) BSSTurfa Runoff from CAFO manure 

applied to land 

No incorporation of manure into soil 

0.02 0.05 0.08 0.05 0.03 

Incorporation of manure into soil within a day 

0.02 0.0031 0.01 0.0031 0.002

Runoff from non-regulated small CAFO 0.02 0.25 0.41 0.25 0.21 

RangeBSSb Runoff from rangeland 0.02 0.005 0.01 0.005 0.00Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)FL Turf Runoff from CAFO manure 

applied to land 

No incorporation of manure into soil 

0.027 0.02 0.03 0.02 0.02 

Runoff from non-regulated small CAFO 0.027 0.14 0.23 0.14 0.10 Runoff from rangelandb,c 0.027 0.0006 0.0010 0.0006 0.000

PA Turf Runoff from CAFO manure 

applied to land 

No incorporation of manure into soil 

0.027 0.04 0.07 0.04 0.03 

Incorporation of manure into soil within a day 

0.027 0.0022 0.0036 0.0022 0.001

Runoff from non-regulated small CAFO 0.027 0.29 0.47 0.29 0.23 Runoff from rangelandb,c 0.027 0.0013 0.0021 0.0013 0.001

AU = animal unit * Used to calculate RQs a Used as surrogate scenario for pasture land b Cattles grazing on rangeland c In absence of rangeland scenario in FL and PA, turf scenarios from FL and PA were used as surrogate scenarios for rangeland. 
28 

Table 4-7. Estimated Environmental Concentrations (EECs) of Coumaphos in Pore Water from Runoff foApplication Scenarios 

PRZM/ EXAMS Scenario 

Sources of a.i. from Application Scenario 

Wash-Off 

Fraction 

Peak EEC(parent+oxon)

(μg/L) 

(Coumaphos + Coumaphoxon) 

21-day EEC(parent+oxon)

(μg/L) 

(Coumaphos + Coumaphoxon) 

Surfa

Por

P

Texas: Spray Application (42% flowable concentrate)BSSTurf Runoff from non-regulated 

small CAFO 

0.02 0.17 0.17 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)PA Turf Runoff from non-regulated 

small CAFO 

0.027 0.19 0.19 

a Peak EEC(parent+oxon) for aquatic invertebrates from Table 4-6
29 

4.2.3 Wash-off from the Skin of Treated Livestock That Enter Bodies of 

Water 

For aquatic exposure from wash-off from the skin of treated livestock that enter bodies of water: 

 Surface water EECs were calculated as “EEC per treated cow wading into a body of 

water” (i.e., EEC/cow; Table 4-8) using the maximum single application rates of 0.027 

and 0.01 lb a.i./animal for Texas and the rest of the U.S., respectively. The equation 

provided in Table 4-9 was used to generate surface water EECs for coumaphos which 

were then adjusted using the TEQ and TTR approaches to yield total EECs (coumaphos 

+ coumaphoxon). 

 Pore water EECs were calculated as EEC/cow (Table 4-10) using surface water EECs 

(Table 4-6) and the ratio of surface water EEC(parent+oxon): pore water EEC(parent+oxon) for 

runoff (Table 4-7). 

Table 4-8. Surface Water Estimated Environmental Concentrations (EECs) from WashOff from the Skin of Treated Livestock That Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fractionc

Peak 

EEC (parent)

/cowd

(μg/L) 

(Coumaphos) 

Peak EEC(parent+oxon)/cowd

(μg/L) 

(Coumaphos + Coumaphoxon) 

Chronic 

EEC(parent+oxon)/cowd

(μg/L) 

(Coumaphos + 

Coumaphoxon) 

Type (lb a.i./ 

animal)a

(mg a.i./ 

ft2 cow hide)b

Fish Aquatic 

Invertebrates 

and Plants 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 0.008 0.013 0.008 0.008 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 0.004 0.007 0.004 0.004 a Table 2-1

b

 See Table 4-12 for calculation c Table 4-1

d

 EEC per treated cow wading into a body of water that is 1 acre, 6 feet deep; calculated using equation in Table 4-4

Table 4-9. Equation for Calculating Estimated Environmental Concentration (EEC) per 

Treated Cow Wading into a 1 Acre, 6 foot Deep Body of Watera

 (i.e., EEC/Cow) 12

EEC/cow = 

surface area of cow in square feeta

x μg coumaphos per square feet of hideb

x fraction of cow surface submerged in a body of water containing non-target organisms (i.e., 0.25)c

x wash-off fraction 

x 2.205 x 10-9 lb/μg 

x 61 μg/L concentration in pond per lb loading a

 The surface area of a 1000-2000 lb cow is about 45 sq ft, based on communication from Jerry Breiter of the U.S. 

Hide, Skin and Leather Association (USHSLA) (USEPA, 1996). 

b

 see Table 4-12 for calculation c

 A cow will generally enter water up to the hair break line, which is a clearly visible line on the sides of the cow, 

where the types of hair change visibly. According to the USHSLA, this means that about 25% of the skin surface 

is submerged (USEPA, 1996). 

 

12 For details on calculation of EEC, see USEPA, 1996. 
30 

Table 4-10. Pore Water Estimated Environmental Concentrations (EECs) from Wash-Off 

from the Skin of Treated Livestock That Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fractionc

Peak EEC(parent+oxon)/cowd,e

(μg/L) 

(Coumaphos + Coumaphoxon) 

Chronic EEC(parent+oxon)/cowd,e

(μg/L) 

(Coumaphos + Coumaphoxon) 

Type (lb a.i./ 

animal)a

(mg a.i./ 

ft2 cow hide)b

Benthic Invertebrates 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 0.005 0.007 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 0.003 0.003 a Table 2-1

b

 See Table 4-12 for calculation c Table 4-1

d

 EEC per treated cow wading into a body of water that is 1 acre, 6 feet deep; calculated using equation in Table 4-4 e

 = surface water EEC from Table 4-8 / ratio of surface water EEC(parent+oxon): pore water EEC(parent+oxon) from Table 

4-7

4.3 Terrestrial Exposure 

4.3.1 Birds and Mammals 

Birds may be exposed to coumaphos via contact with/ingestion of hair and skin debris from 

treated cattle and/or contaminated soil and feed in and around treatment areas. Additionally, 

birds and mammals may be exposed to coumaphos via ingestion of coumaphos-contaminated 

bird carcasses, ingestion of food items on land receiving manure from CAFOs, and ingestion of 

contaminated fish. 

4.3.1.1 Contact with/Ingestion of Hair and Skin Debris from 

Treated Cattle and/or Contaminated Soil and Feed in and 

around Treatment Areas (Primary Exposure) 

Evidence for avian exposure via contact with/ingestion of hair and skin debris from treated cattle 

and/or contaminated soil and feed in and around treatment areas has been confirmed by a pilot 

field study submitted to the Agency (MRID 42512604). Eight cattle in one pen were sprayed 

with coumaphos (2 lb a.i. in 50 gal water) until each individual was thoroughly soaked. After 

treatment, coumaphos residues were detected in soil samples, cow feces, cow hair samples, and 

stomach contents of cowbirds (see Table 4-11 for residues in soil, hair, and feces). Brain 

cholinesterase activity was inhibited 2-59% in 13 of 19 cowbirds examined. Thirty-four bird 

species were recorded within 200 m of the treatment site, with six species observed on the 

ground in the pen. Based on several counts, 290 birds were estimated to frequent the 3.7-hectare 

pen. The results from treating only 8 cows in one pen were too limited in scope to draw any 

major conclusions. However, the study did indicate that a variety of birds are likely to be present 

at treatment sites and that they may be exposed to coumaphos residues from soil from cowpens, 

bovine feces, and bovine hair. The study also included information regarding bird use of 

feedlots and pastures, and species likely to be exposed, ranked in order of potential exposure in 

feedlots. Due to its close association with cattle, the black-billed magpie was listed as the 

species most likely to be exposed. 
31 

Table 4-11. Coumaphos Residues (Mean ± SD ppm) for Pilot Field Study (MRID 

42512604) 

Source Pre-Treatment Hours Post-Treatment 

1 24 72 

Soil from cowpens 50.7 ± 21.3 

(n = 8) 

344 ± 251 

(n = 16) 

114 ± 137 

(n = 8) 

142 ± 153 

(n = 8) 

Bovine hair 0.164 ± 0.126 

(n = 8) 

1,228 ± 158 

(n = 8) 

853 ± 250 

(n = 8) 

370 ± 98 

(n = 8) 

Bovine feces* 0.0962 ± 0.1847 

(n = 8) 

0.0791 ± 0.1346 

(n = 7) 

0.0088 ± 0.0080 

(n = 8) 

≤ 0.0015 ± 0 

(n = 8) 

* collected via rectal palpation 

Mass of coumaphos per square foot of cow hide was used a conservative dose-based estimated 

exposure concentration (EEC) for characterizing exposure of birds to coumaphos via contact 

with/ingestion of hair and skin debris from treated cattle and/or contaminated soil and feed in 

and around treatment areas (Table 4-12). Dose-based EECs were calculated for the maximum 

single application rates based on information from labels (i.e., Texas, dip vat application: 0.027 

lb a.i./animal; rest of U.S., back rubber application: 0.01 lb a.i./animal) and information from the 

U.S. Hide, Skin and Leather Association (USHSLA). 

Mean residues of coumaphos detected in bovine hair (a surrogate for potential contaminated food 

items) 1, 24, and 72 hours post-treatment as reported in the pilot field study (MRID 42512604) – 

1228, 853, and 370 mg a.i./kg-diet, respectively – were used as dietary-based EECs for 

characterizing exposure of birds to coumaphos via contact with/ingestion of hair and skin debris 

from treated cattle and/or contaminated soil and feed in and around treatment areas. 

Table 4-12. Dose-Based Estimated Environmental Concentrations (EECs) for Treated 

Cow Hide 

Maximum Application Rate Cow Hide Surface Areaa

(ft2) 

Dose-Based EEC 

(mg a.i./ft2 Type (lb a.i./animal) (mg a.i./animal) cow hide) 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 12,247 45 272 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 4,536 45 101 

a The surface area of a 1000-2000 lb cow is about 45 sq ft, based on communication from Jerry Breiter of the U.S. 

Hide, Skin and Leather Association (USHSLA) (USEPA, 1996). 

4.3.1.2 Ingestion of Coumaphos-Contaminated Bird Carcasses 

(Secondary Exposure) 

Dose- and dietary-based EECs for secondary exposure of birds and mammals via ingestion of 

coumaphos-contaminated bird carcasses were calculated. Both types of EECs required the 

estimation of the concentration of coumaphos in a bird carcass since no empirical residue data 

are available. 

The concentration of coumaphos in a bird carcass (mg a.i./g-bw) was assumed to be equivalent 

to potential coumaphos intake on a single day (mg a.i./g-bw/day) by the species most likely to be 

exposed to coumaphos according to the pilot field study (MRID 42512604), the black-billed 

magpie. In turn, the potential coumaphos intake on a single day by a black-billed magpie was 
32 

assumed to represent the maximum concentration in the carcass (i.e., there is no longer term 

accumulation of residues in the tissue beyond what would be expected from intake on a single 

day). The concentrations of coumaphos in food items –1228, 853, and 370 mg a.i./kg-diet = 

1.228, 0.853, and 0.370 mg a.i./g-diet – were assumed to be equivalent to the mean residues of 

coumaphos detected in bovine hair (a surrogate for potential contaminated food items) 1, 24, and 

72 hours post-treatment, respectively, as reported in the pilot field study (MRID 42512604). 

Using the formulas and additional assumptions provided in Table 4-13, the concentrations of 

coumaphos in a black-billed magpie carcass were estimated to range from 0.039 to 0.129 mg 

a.i./g-bw. 

Dose-based EECs for secondary exposure of birds and mammals via ingestion of coumaphoscontaminated bird carcasses were assumed to be equivalent to the potential coumaphos intake on 

a single day (i.e., mg a.i./g-bw/day) by a red-tailed hawk and a red fox, respectively. These two 

predators/scavengers were chosen because they are representative of a mammal and bird, 

respectively, that could be exposed secondarily to coumaphos via ingestion of contaminated bird 

carcasses. Assumptions and formulas used to calculate potential daily coumaphos intake by 

birds and mammals via secondary exposure are provided in Table 4-13. Dosed-based EECs as 

coumaphos intake for this route of exposure were estimated to range from 4.16 x 10-6 to 1.38 x 

10-5 mg a.i./g-bw/day and 1.17 x 10-5 to 3.87 x 10-5 mg a.i./g-bw/day for the red fox and redtailed hawk, respectively. Assuming no degradation of coumaphos in the contaminated bird 

carcass prior to consumption by the predator/scavenger (e.g., red-tailed hawk and red fox, 

respectively), dietary-based EECs for secondary exposure of birds and mammals via ingestion of 

coumaphos-contaminated bird carcasses were estimated to range from 0.039 to 0.129 mg a.i./gdiet, the range of estimated concentrations of coumaphos in a bird carcass. 

 
33 

Table 4-13. Assumptions and Formulas Used to Calculate Coumaphos Intake (CI) via (a) 

Primary and (b) Secondary Exposure 

a) Primary exposurea

Assumptions 

 The black-billed magpie, the species most likely to be exposed to coumaphos according to the pilot field study 

(MRID 42512604), is the consuming individual. 

 The weight of a black-billed magpie (Pica pica) is 186 g (Dunning, 1984). 

 The concentrations of coumaphos in food items –1228, 853, and 370 mg a.i./kg-diet = 1.228, 0.853, and 0.370 

mg a.i./g-diet – are the mean residues of coumaphos detected in bovine hair (a surrogate for potential 

contaminated food items) 1, 24, and 72 hours post-treatment, respectively, as reported in the pilot field study 

(MRID 42512604). 

 Bovine hair is 100% dry material. Thus, food dry weight is equivalent to food wet weight. 

 The black-billed magpie consumes 100% of its diet as food items contaminated with coumaphos at a 

concentration of 1.228, 0.853, or 0.370 mg a.i./g-diet. 

Formulas 

FIb (g dry-wt/day)(black-billed magpie) = 0.648 * Wt (g)0.651 = 0.648 * (186)0.651 = 19.5 g dry-wt/day 

FI (g wet-wt/day)(black-billed magpie) = FI (g dry-wt/day) (black-billed magpie) = 19.5 g wet-wt/day 

CI (mg/g-bw/day)(black-billed magpie) = FI (g wet-wt/day) (black-billed magpie) * Coumaphos dietary concentration (mg a.i./gdiet)

Wt(g) 

= (19.5 * [0.370, 0.853, or 1.228]) / 186 

= 0.039, 0.089, or 0.129 mg a.i./g-bw/day

Where: 

FI = food intake 

CI = coumaphos intake 

Wt = weight 

Coumaphos dietary concentration (mg/g-diet) = 1.450 mg a.i./g-dietd

b) Secondary exposuree

Assumptions 

For mammals: For birds: 

 The red fox (Vulpes vulpes) is the consuming 

individual. 

 The weight of a red fox is 4.5 kg = 4500 g 

(USEPA, 1993b) 

 The daily intake rate of a red fox is 0.16 g drywt/g-bw (USEPA, 1993b). 

 The red-tailed hawk (Buteo species) is the 

consuming individual. 

 The weight of a red-tailed hawk is 1.1 kg = 1100 g 

(USEPA, 1993b) 

 The daily intake rate of red-tailed hawk is 0.11 g 

dry-wt/g-bw (USEPA, 1993b). 

For birds and mammals: 
34 

 A bird carcass is 67% water (USEPA, 1993b). 

 A red fox/red-tailed hawk consumes 100% of its diet as bird carcasses contaminated with coumaphos at a 

concentration of 0.129, 0.089, or 0.039 mg a.i./g-bw/day (calculated in (a)). 

 There is no degradation of coumaphos in a bird carcass prior to consumption by a red fox/red-tailed hawk. 

Formulas 

FI (g wet-wt/day) = FI (g dry-wt/day) / 0.33 

FI (g wet-wt/day)(red fox) = 0.16/0.33 = 0.48 g wet-wt/day 

FI (g wet-wt/day)(red-tailed hawk) = 0.11/0.33 = 0.33 g wet-wt/day 

CI (mg/g-bw/day) = FI (g wet-wt/day) * Coumaphos dietary concentration (mg a.i./g-diet)

Wt(g) 

CI (mg/g-bw/day) (red fox) = (0.48 * [0.039, 0.089, or 0.129])/4500 

 = 4.16 x 10-6, 9.49 x 10-6, or 1.38 x 10-5 mg a.i./g-bw/day

CI (mg/g-bw/day) (red-tailed hawk) = (0.33 * [0.039, 0.089, or 0.129])/1100 

 = 1.17 x 10-5, 2.67 x 10-5, or 3.87 x 10-5 mg a.i./g-bw/day

Where: 

FI = food intake 

CI = coumaphos intake 

Wt = weight 

Coumaphos dietary concentration (mg/g-diet) = 0.152 mg a.i./g-diet 

a ingestion of contaminated food items 

b

 equation for all birds (USEPA, 1993b, pg. 3-4) 

c

 for females (Dunning, 1984) 

d

 highest coumaphos residue detected in potential contaminated food items (e.g., soil, hair, feces) as reported in the 

pilot field study (MRID 42512604) e ingestion of coumaphos-contaminated bird carcasses

4.3.1.3 Ingestion of Food items on Land Receiving Manure from 

CAFOs 

EECs for ingestion of food items on land receiving manure from CAFOs were calculated using 

the T-REX model13 (v1.5.2; June 6, 2013), a Tier 1 model for screening-level assessments of 

pesticides. T-REX estimates terrestrial animal exposure values resulting from possible dietary 

ingestion of pesticide residues present on non-food and food items. The T-REX model 

determines (1) EECs for birds and mammals and (2) risk to birds and mammals via calculation of 

risk quotients (RQs). In all screening-level assessments, the organisms are assumed to consume 

100% of their diet as one food type. EECs in terms of LD50/ft2 and associated RQs for broadcast 

granular applications were deemed to be most applicable to exposure via ingestion of food items 

on land receiving manure from CAFOs. 

Input parameters for broadcast granular applications include a maximum application rate, 

number of applications, application interval, and definitive acute LD50 toxicity endpoints for 

birds and mammals (Table 4-14). 

 

13 http://www.epa.gov/oppefed1/models/terrestrial/index.htm
35 

Table 4-14. Input Parameters for T-REX Modeling of Broadcast Granular Applications 

(Surrogate for CAFO Manure Applied to Land) 

Source of Exposure 

 

Input Parameters 

Maximum 

Single 

Application 

Ratea 

(lb a.i./A) 

Maximum 

Annual 

Number of 

Applicationsa

Other Parameters 

Texas: Spray Application (42% flowable concentrate) 

Avian LD50 = 2.4 mg/kg-bw 

 (bobwhite quail; MRID 

00112843) 

Mammalian LD50 = 17 mg/kg-bw 

(rat; MRID 00110597) 

CAFO manure 

applied to land 

No incorporation into 

soil 0.015 1 

Incorporation into 

soil within a day 0.009 1 

Rest of U.S.: Back Rubber Application 

(11.6% emulsifiable concentration) 

CAFO manure 

applied to land 

No incorporation into 

soil 0.0092 1 

Incorporation into 

soil within a day 0.0051 1 

a Table 4-2 

Results of T-REX modeling of coumaphos EECs in terms of LD50/ft2 from application of CAFO 

manure to land are provided in Tables 4-15. 

Table 4-15. Avian and Mammalian Estimated Exposure Concentrations (EECs) for 

Application of CAFO Manure to Land

Source of Exposure EEC: LD50/ft2 

(mg a.i./ft2) 

Texas: Spray Application (42% flowable concentrate) 

CAFO manure applied to land No incorporation into soil 0.16 

Incorporation into soil within a day 0.09 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration) 

CAFO manure applied to land No incorporation into soil 0.10 

Incorporation into soil within a day 0.05 

4.3.1.4 Ingestion of Contaminated Fish 

EECs for ingestion of contaminated fish were calculated using KABAM (KOW (based) Aquatic 

BioAccumulation Model; v. 1.0; April 9, 2009). KABAM estimates potential bioaccumulation 

of hydrophobic organic pesticides in freshwater aquatic food webs and subsequent risks to 

mammals and birds via consumption of contaminated fish. KABAM is composed of two parts: 

1) a bioaccumulation model estimating pesticide concentrations in aquatic organisms and 2) a 

risk component translating exposure and toxicological effects of a pesticide into risk estimates 

for mammals and birds consuming contaminated fish. The bioaccumulation portion of KABAM 

is based on an aquatic food web bioaccumulation model published by Arnot and Gobas (2004). 

The bioaccumulation portion of KABAM relies on a pesticide’s octanol-water partition 

coefficient (KOW) to estimate uptake and elimination constants through respiration and diet of 

aquatic organisms in different trophic levels. Pesticide tissue concentrations in aquatic organisms 

are calculated for different trophic levels of a food web through diet and respiration. In the risk 
36 

component of KABAM, pesticide concentrations in aquatic organisms are used to estimate doseand dietary-based exposures and associated risk quotients for mammals and birds consuming 

aquatic organisms. 

Input parameters for KABAM include Log Kow (=4.3), Koc (=5904 L/kg oc), a pore water EEC, 

a water column EEC, rate constants for various tropic levels (e.g., default metabolism rate 

constant, Km = 0), and definitive toxicity endpoints for birds and mammals (see Appendix B, 

Table B-1). For runoff, EECs for the scenarios that yielded the highest values (i.e., Texas: 

BSSTurf, runoff from unregulated small CAFO; rest of the U.S.: PA Turf, runoff from 

unregulated small CAFO) were used. For wash-off from treated livestock that enter bodies of 

water, this analysis was conducted using the EEC for wash-off fraction 0.02 (Texas) or 0.027 

(rest of the U.S.) and 100 cows entering a body of water. The upper limit of 100 cows was 

selected based on literature indicating that a 6 foot deep, 1 acre farm pond would be suitable for 

watering 100 cows (Bray, 2013). 

Results indicated RQ exceedances so model inputs were refined to more accurately reflect the 

fast elimination of coumaphos in fish as documented in the BCF study (MRIDs 00115168 and 

00150619). Specifically, the fish BCF study shows that 95% of accumulated coumaphos is 

depurated within 24 hours of fish being place in clean water. Raw data from the BCF study was 

used to calculate a fish Km of 0.936/day. This Km was used as an input for small, medium, and 

large fish, and KABAM was allowed to calculate the remaining rate constants (e.g., uptake an 

elimination constants through diet and respiration) for fish. 

4.3.2 Terrestrial (Upland and Semi-Aquatic) Plants 

Terrestrial (upland and semi-aquatic) plants could be exposed to coumaphos via uptake from 

CAFO manure applied to land and uptake from soil receiving runoff from land to which manure 

from CAFOs has been applied. 

EECs for exposure via uptake from soil receiving runoff from land to which manure from 

CAFOs has been applied were calculated using TerrPlant (v1.2.2; October 29, 2009)14. 

TerrPlant, a Tier 1 model for screening-level assessments of pesticides, is used to estimate 

exposure to terrestrial plants from single pesticide applications; the model does not consider 

exposures to plants from multiple pesticide applications. TerrPlant determines (1) EECs in 

runoff and in spray drift and (2) risk to non-listed and listed species of monocots and dicots 

inhabiting dry (upland) and semi-aquatic areas via calculation of risk quotients (RQs). 

Input parameters for TerrPlant include maximum single application rate, incorporation depth (1 

inch; default), runoff fraction (2% based on the water solubility of coumaphos – 20 mg/L), spray 

drift fraction, and definitive toxicity endpoints from seedling emergence and vegetative vigor 

studies (Table 4-16). Given that exposure via this pathway includes runoff only, a spray drift 

fraction of 0% was assumed. EECs used to evaluate potential risk to terrestrial plants for runoff 

from land to which manure from CAFOs has been applied are provided under the column titled 

“Runoff EECs” in Table 4-17. 

 

14 http://www.epa.gov/oppefed1/models/terrestrial/index.htm
37 

EECs for the exposure via uptake from CAFO manure applied to land were assumed to be 

equivalent to application rates calculated for unincorporated manure in Table 4-2 and are 

provided under the column titled “Direct Application EEC” in Table 4-17. 

Table 4-16. Input Parameters for TerrPlant Modeling 

Source of Exposure Input Parameters 

Application Rate 

(lb a.i./A) 

Other Parameters 

Texas: Spray Application (42% flowable concentrate)

Incorporation depth = ≤ 1 inch 

Runoff fraction = 2% 

Spray drift fraction = 0% 

SE endpoints: Nonea 

VV endpoints: Nonea

Runoff from land to 

which CAFO manure 

has been applied 

No incorporation into 

soil 0.015 

Incorporation into 

soil within a day 0.009 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Runoff from land to 

which CAFO manure 

has been applied 

No incorporation into 

soil 0.0092 

Incorporation into 

soil within a day 0.0051 

SE = seedling emergence; VV = vegetative vigor 

a

 The are no toxicity data that are specific to coumaphos and suitable for calculation of RQs. 

Table 4-17. Terrestrial (Upland and Semi-aquatic) Plant Estimated Exposure 

Concentrations (EECs) for CAFO Manure Applied to Land 

Source of Exposure Application 

Ratea

Direct Application 

EECc 

(lb a.i./A) 

Runoff EECb 

(lb a.i./A) 

All Areas Dry (Upland) 

Areas 

Semi-Aquatic 

Areas 

Texas: Spray Application (42% flowable concentrate)

CAFO manure 

applied to land 

No incorporation 

into soil 0.015 

0.015 

0.0003 0.003 

Incorporation into 

soil within a day 0.009 0.00018 0.0018 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

CAFO manure 

applied to land 

No incorporation 

into soil 0.0092 

0.0092 

0.000184 0.00184 

Incorporation into 

soil within a day 0.0051 0.000102 0.00102 

a

 From Table 4-2 b

 From TerrPlant 

c

 assumed to be equivalent to application rates calculated for unincorporated manure 

4.3.3 Honey Bees (In-Hive Use) 

Honey bees may be exposed to coumaphos via impregnated strips placed in hives to control 

varroa mites and hive beetles. Data on coumaphos residues (mg/kg) detected in bees, wax, and 

queen cells from hives with coumaphos-impregnated strips are available from open literature 

study E066848 as identified via ECOTOX15 (Table 4-18). The former study (E066848), which 

was classified as “qualitative” for use in the assessment (see Section 5.2.3 for rationale), 

described two separate experiments with coumaphos. In one experiment, colonies received 

 

15 http://cfpub.epa.gov/ecotox/
38 

plastic strips containing no coumaphos (control), a low dose of coumaphos (i.e., 1⁄4 coumaphosimpregnated strip per frame in the starter colonies and 1⁄4 strip per mating nuc), or a high dose of 

coumaphos (i.e., 1⁄2 coumaphos-impregnated strip per frame in starter colonies and 1⁄2 strip per 

mating nuc). In the second experiment, colonies received hanging plastic strips containing no 

coumaphos (control), 3 coumaphos-impregnated strips adjacent to cell frames but not touching 

the cell frames, 3 coumaphos-impregnated strips adjacent to cell frames, or 3 coumaphosimpregnated strips cut up and attached directly to each cell bar (1⁄2 strip per bar). Concentrations 

in bees, wax and queen cells of hives treated with coumaphos-impregnated strips ranged from 

0.83-23.26, 12.69-120, and 8.11-237 mg/kg, respectively (Table 4-18). 

Table 4-18. Coumaphos Residues in Samples of Bees, Wax, and Queen Cells from Hives 

Treated with Coumaphos-Impregnated Stripsa

Sample type Treatment Pre-Treatment 

Concentration (mg/kg) 

Post-Treatment Concentration 

(mg/kg) 

Experiment #1 

Bee 

Controlb

 < Level of detection 0.13 

Lowc < Level of detection 0.83 

Highd 1.54 6.47 

Wax 

Controlb

 < Level of detection 0.17 

Lowc 0.30 49.7 

Highd 0.36 120 

Queen cells 

Controlb

Not applicable 

< Level of detection 

Lowc 181 

Highd 237 

Experiment #2 

Bee 

Controlb

Did not measure 

0.57 

2 strips attachede 3.36 

2 strips adjacentf 23.26 

2 strips not touchingg 9.95 

Wax 

Controlb

Did not measure 

<LOD 

2 strips attachede 12.69 

2 strips adjacentf 22.22 

2 strips not touchingg 12.85 

Queen cells 

Controlb

Did not measure 

NA 

2 strips attachede 91.93 

2 strips adjacentf 28.17 

2 strips not touchingg 8.11 a

 Source of data: Open literature study E066848 as identified via ECOTOX 

b

 plastic strips containing no coumaphos 

c

 1⁄4 coumaphos-impregnated strip per frame in the starter colonies and 1⁄4 strip per mating nuc 

d

 1⁄2 coumaphos-impregnated strip per frame in starter colonies and 1⁄2 strip per mating nuc 

e

 3 coumaphos-impregnated strips cut up and attached directly to each cell bar (1⁄2 strip per bar) f

 3 coumaphos-impregnated strips adjacent to cell frames 

g

 3 coumaphos-impregnated strips adjacent to cell frames but not touching the cell frames 

In addition, data for coumaphos residues in comb wax, stored pollen, and live bees as well as 

coumaphos oxon residues in wax from a broad survey of pesticide residues sampled from 

commercial bee hives in North America are available (MRID 49497801; Table 4-22). 

Concentrations of coumaphos in wax, pollen, and bees ranged from 0.001-91.9, 0.001-5.83, and 

0.001-0.762 mg/kg, respectively, and concentration of coumaphos in wax ranged from 0.0013-

1.3 mg/kg. 
39 

Table 4-22: Summary of Coumaphos Detections in Samples from North American Honey 

Bee Coloniesa

Sample 

Type 

Detects 

(%) 

Number 

of 

Samples 

Analyzed 

Detections (mg/kg) 

High Low Median 90% 

tile 

95% 

tile 

Mean SEM LOD 

Coumaphos 

Wax 254 (98.1) 259 91.9000 0.0010 1.2400 6.8750 11.3400 3.30040 0.49980 0.0010 

Pollen 263 (75.1) 350 5.8280 0.0010 0.0131 0.5184 0.8920 0.1804 0.0330 0.0010 

Bees 84 (60.0) 140 0.7620 0.0010 0.0080 0.1187 0.1562 0.0504 0.0135 0.0010 

Coumaphos oxon 

Wax 187 (98.9) 208 1.3000 0.0013 0.0561 0.1842 0.2698 0.1027 0.0125 0.0050 

LOD = level of detection; SEM = standard error of the mean 

a

 Source of data: MRID 49497801 
40 

5 Effects Characterization 

Data are obtained from registrant-submitted studies or from open literature studies identified by 

ECOTOX16 to characterize the effects of coumaphos to non-target organisms. Additional effects 

characterization is provided by reviews of reported incidents involving use of coumaphos. 

A data call-in (DCI) was issued for two toxicity studies after the 2008 problem formulation: 

 850.4400 – Aquatic Plant Toxicity Test 

 850.5400 – Algal Toxicity 

The registrant subsequently submitted a Tier II aquatic vascular plant study with Lemna gibba

(MRID 48322801) and a Tier II aquatic non-vascular plant study with the green alga 

Pseudokirchneriella subcapitata (MRID 48322802). The study with L. gibba yielded an EC50 of 

166 μg a.i./L and a NOAEC of 166 μg a.i./L and was classified as “supplemental” due to a 

guideline deviation (i.e., a the number of plants per replicate was lower than recommended); the 

study with P. subcapitata was classified as “invalid” because the solvent had a stimulatory effect 

that could have masked the true effects of coumaphos. An additional aquatic non-vascular plant 

study for coumaphos was not requested based on an analysis presented in an EFED memo 

indicating that aquatic non-vascular plant toxicity data for a surrogate organophosphate 

insecticide could be used to characterize the toxicity of coumaphos to aquatic non-vascular 

plants (DP 406398, October 31, 2012; see Section 5.1.6 for additional details). 

There are several open literature studies on the effects of coumaphos to bees that are used in this 

assessment (see Table 5-6). Other open literature studies also referenced coumaphos, but these 

are not included in this assessment because: the reported toxicity endpoints are less sensitive than 

those from registrant-submitted studies; the information is not appropriate for inclusion for a 

variety of reasons including the reported endpoint is not comparable to a guideline endpoint; or 

the reported endpoint is not convertible to units used in risk assessment models. Coumaphos 

studies that are found in the open literature and passed the initial screen but were not used in the 

assessment are provided in Appendix C. 

5.1 Effects to Aquatic Organisms 

Summaries of data used to characterize the effects of coumaphos to aquatic organisms are 

provided in Table 5-1. The most sensitive definitive toxicity endpoints used in RQ calculations 

are bolded. 

5.1.1 Freshwater Fish 

Based on studies with bluegill sunfish, lake trout, walleye, channel catfish, cutthroat trout, 

rainbow trout, and largemouth bass, coumaphos is moderately to highly toxic to freshwater fish 

on an acute basis. 

 

16 http://cfpub.epa.gov/ecotox/
41 

In studies with bluegill sunfish, lake trout, walleye, channel catfish, cutthroat trout, rainbow 

trout, and largemouth bass (MRID 40098001), LC50’s ranged 340 to 1100 μg a.i./L. No 

sublethal effects were specified in these studies. 

In a second study with bluegill sunfish (MRID 00112840), the LC50 was 5000 μg a.i./L, and the 

sublethal effect of erratic swimming was noted. In a second study with rainbow trout (MRID 

00112840), the LC50 was 5900 μg a.i./L, and sublethal effects including erratic swimming, loss 

of reflex, and discoloration were observed. 

In an early life-stage study with rainbow trout (MRID 43066301), the NOAEC of 11.7 μg a.i./L 

was based on the most sensitive endpoints of length and weight (day 62). However, day 36 posthatch survival and length were also affected at ≥ 96.1 μg a.i./L, and day 62 post-hatch survival 

was affected at ≥ 48.4 μg a.i./L. 

Since the freshwater fish chronic toxicity endpoint of 11.7 μg/L (rainbow trout; MRID 

43066301) was not generated using the most acutely sensitive freshwater fish (i.e., bluegill 

sunfish), a chronic toxicity endpoint for bluegill sunfish of 4.4 μg/L was calculated using the 

acute toxicity endpoint for bluegill sunfish and an acute to chronic ratio (ACR) for rainbow trout 

(see Table 5-1 for calculation). 

5.1.2 Estuarine/Marine Fish 

Based on an acute toxicity study with sheepshead minnow, coumaphos is highly toxic to 

estuarine/marine fish. The LD50 for this study (MRID 40228401) was 280 μg a.i./L; sublethal 

effects were not specified. 

No data are available for the chronic toxicity of coumaphos to estuarine/marine fish. Therefore, 

a chronic toxicity endpoint for estuarine/marine fish of 3.6 μg/L was calculated using the acute 

toxicity endpoint for sheepshead minnow and an ACR for freshwater fish (i.e., rainbow trout) 

(see Table 5-1 for calculation). 

 
42 

Table 5-1. Endpoints Used to Characterize the Effects of Coumaphos to Aquatic Organisms 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpointsa,b (Effects) & Acute Toxicity 

Classification (if applicable) 

Survival, growth, and reproduction of freshwater fish (surrogate for aquaticphase amphibians) 

Most sensitive freshwater fish acute LC50

95 Bluegill sunfish 

(Lepomis macrochirus) 

96-hr LC50 = 340 μg a.i./L 

Highly toxic 

95 Lake trout 

(Salvelinus namaycush) 

96-hr LC50 (95% C.I.) = 593 (416-846) μg a.i./L 

Highly toxic 

95 Walleye 

(Stizostedion vitreum vitreum) 

96-hr LC50 (95% C.I.) = 780 (645-943) μg a.i./L 

Highly toxic 

95 Channel catfish 

(Ictalurus punctatus) 

96-hr LC50 (95% C.I.) = 840 (620-1140) μg a.i./L 

Highly toxic 

95 Cutthroat trout 

(Salmo clarki) 

96-hr LC50 (95% C.I.) = 862 (645-1150) μg a.i./L 

Highly toxic 

95 Rainbow trout 

(Salmo gairdneri) 

96-hr LC50 = 898 μg a.i./Lc

Highly toxic 

95 Largemouth bass 

(Micropterus salmoides) 

96-hr LC50 (95% C.I.) = 1100 (1000-1200) μg a.i./L 

Moderately toxic 

99.6 Bluegill sunfish 

(Lepomis macrochirus) 

96-hr LC50 (95% C.I.) = 5000 (4000-6300) μg a.i./L Probit slope (95% C.I.) = 4.4 (2.7-6.0) (0, 10, 20, 40, 70, 90, and 100% mortality at 1500, 2200, 3200, 4700, 6900, 10000, and 15000 μg a.i./Lsublethal effects: erratic swimming) Moderately toxic 

99.6 Rainbow trout 

(Oncorhynchus mykiss) 

96-hr LC50 (95% C.I.) = 5900 (5100-6900) μg a.i./L Probit slope (95% C.I.) = 13.0 (5.4-20.6) (0, 10, 80, 100, and 100% mortality at 3200, 4700, 6900, 10000 and 15000 μg a.i./L; sublethal effects: erratic swimming, loss of reflex, and discoloration) Moderately toxic 

NA Bluegill sunfish Estimated chronic NOAEC(bluegill sunfish) 
43 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpointsa,b (Effects) & Acute Toxicity 

Classification (if applicable) 

Most sensitive freshwater fish chronic NOAEC 

(Lepomis macrochirus) 

= Acute LC50(bluegill sunfish) / ACR(rainbow trout)

= 340 μg/L / 77  = 4.4 μg/L Where: ACR(rainbow trout)

= Acute LC50(rainbow trout) / Chronic NOAEC(rainbow trout

= 898 μg/L / 1.6 μg/L = 77 

96.2 

(TGAI) 

99.1 

(Radiolabeled) 

Rainbow trout (Oncorhynchus mykiss) 

Early life-stage 62-day NOAEC = 11.7 μg a.i./L 62-day LOAEC = 24.6 μg a.i./L (based on most sensitive endpoints of length and weight; day 36 post-hatch survival and length also affected at ≥ 96.1 μg a.i./L; day 62 post-hatch 

survival also affected at ≥ 48.4898 μg a.i./L) 

Survival, growth, and reproduction of estuarine/marine fish 

Most sensitive estuarine/marine fish acute LC50

95 Sheepshead 

minnow (Cyprinodon variegatus) 

48-hr LC50 = 280 μg a.i./L (nom) 

Highly toxic 

Most sensitive estuarine/marine fish chronic NOAEC 

NA Sheepshead 

minnow (Cyprinodon variegatus) 

No data Estimated chronic NOAEC(sheepshead minnow)

= Acute LC50(sheepshead minnow) / ACR(rainbow trout)

= 280 μg/L / 77  = 3.6 μg/L Where: ACR(rainbow trout)

= Acute LC50(rainbow trout) / Chronic NOAEC(rainbow trout

= 898 μg/L / 1.6 μg/L = 77 

Survival, growth, and reproduction of freshwater invertebrates 

Most sensitive freshwater invertebrate acute EC50

97 Scud 

(Gammarus lacustris) 

96-hr LC50 (95% C.I.) = 0.074 (0.059-0.092) μg a.i.

48-hr LC50 (95% C.I.) = 0.14 (0.082-0.24) μg a.i./L 

Very highly toxic 
44 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpointsa,b (Effects) & Acute Toxicity 

Classification (if applicable) 

95 Scud 

(Gammarus fasciatus) 

96-hr LC50 (95% C.I.) = 0.15 (0.11-0.20) μg a.i./L 

Very highly toxic 

99.64 

(TGAI) 

98.9 

(Radiolabeled) 

Water flea (Daphnia magna) 

48-hr EC50 (95% C.I.) = 0.192 (0.134-0.240) μg a.i./L 

(mm)d

Probit slope (95% C.I.) = 2.7 (1.7-3.7) 48-hr NOAEC < 0.106 μg a.i./L (mm) (30, 50, 65, 80, 85, and 100% immobility at 0.106, 0.210, 0.310, 0.415, 0.523, and 0.614 μg a.i./L) Very highly toxic 

99.64 

(TGAI) 

98.9 

(Radiolabeled)

Scud (Gammarus lacustris) 

48-hr EC50 (95% C.I.) = 0.224 (0.201-0.246) μg a.i./L (mProbit slope (95% C.I.) = 6.6 (5.0-8.3) 48-hr NOAEC = 0.103 μg a.i./L (mm) (0, 25, 35, 55, 80, 95, 100, 100, 100, 100, 100, and 100% immobility at 0.103, 0.154, 0.204, 0.255, 0.320.371, 0.408, 0.514, 0.610, 0.708, and 0.806 μg a.i./Very highly toxic 

Most sensitive freshwater invertebrate chronic NOAEC 

NA Scud 

(Gammarus fasciatus) 

Estimated chronic NOAEC(G. lacustris)

= Acute LC50(G. lacustris) / ACR(D. magna)

= 0.074 μg/L / 6 = 0.0127 μg/L Where: ACR(D. magna)

= Acute EC50(D. magna) / Chronic NOAEC(D. magna)

= 0.192 μg/L / 0.0337 μg/L = 6 

99.1 

(Radiolabeled) 

Water flea (Daphnia magna) 

21-day NOAEC = 0.0337 μg a.i./L (mm) 21-day LOAEC = 0.0758 μg a.i./L (mm) (NOAEC based on survival) 

Survival, growth, and reproduction of estuarine/marine invertebrates 

Most sensitive estuarine/marine invertebrate acute EC50

or LC50

95 Pink shrimp 

(Penaeus duorarum) 

48-hr EC50 = 2.0 μg a.i./L (nom) 

Very highly toxic 

95 Eastern oyster 96-hr EC50 = 290 μg a.i./L (nom) at 221 ppt sal. and 9 °C 

96-hr EC50 = 880 μg a.i./L (nom) at 23 ppt sal. and 9 °C 
45 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpointsa,b (Effects) & Acute Toxicity 

Classification (if applicable) 

(Crassostrea virginica) 

Highly toxic 

Most sensitive estuarine/marine invertebrate chronic NOAEC 

NA Pink shrimp 

(Penaeus duorarum) 

Estimated chronic NOAEC(pink shrimp)

= Acute LC50(pink shrimp) / ACR(D. magna)

= 2.0 μg/L / 6 = 0.3421 μg/L Where: ACR(D. magna)

= Acute EC50(D. magna) / Chronic NOAEC(D. magna)

= 0.197 μg/L / 0.0337 μg/L = 6

Survival, growth, and reproduction of benthic (sedimentdwelling) invertebrates 

Most sensitive be benthic invertebrate acute EC50 or LC50 or 

sub-chronic NOAEC 

No data 

Most sensitive benthic invertebrate chronic NOAEC 

No data 

Survival, growth and reproduction of aquatic plants 

Aquatic non-vascular species: Most sensitive EC50

No data 

Aquatic vascular species: Most sensitive EC50

95.7 Duckweed 

(Lemna gibba) 

Tier II 7-dayEC50 > 166 μg a.i./L (mm) 

7-day NOAEC = 166 μg a.i./L (mm) (no effects) 

C.I. = confidence interval; NA = not applicable a BOLD values used in RQ calculations b mm = mean-measured; nom = nominal c used to calculate freshwater fish acute to chronic ratio d used to calculate freshwater invertebrate acute to chronic ratio 
46 

5.1.3 Freshwater Invertebrates 

Based on studies with Gammarus lacustris, Gammarus fasciatus, and Daphnia magna,

coumaphos is very highly toxic to freshwater invertebrates on an acute basis. 

An acute study with the scud G. lacustris (MRID 05009242) yielded the most sensitive endpoint, 

i.e., LC50 = 0.074 μg a.i./L. This study was classified as “supplemental” due to the life stage of 

the test organisms; adult individuals were used instead of immature individuals, which are 

recommended. A second study with G. lacustris (MRID 41778504), which is classified as 

“acceptable,” had an EC50 of 0.224 μg a.i./L and a NOAEC of 0.103 μg a.i./L based on 

immobility. 

An acute study with another species of scud, G. fasciatus (MRID 05017538), yielded an LC50 of 

0.15 μg a.i./L. This study was classified as “supplemental” due to the life stage of the test 

organisms; adult individuals were used instead of immature individuals, which are 

recommended. 

In the acute study with D. magna (MRID 41778503), the EC50 was 0.192 μg a.i./L, and the 

NOAEC was less than the lowest concentration tested, (i.e., < 0.106 μg a.i./L). This study was 

classified as “supplemental” due to the life stage of the test organisms; adult individuals were 

used instead of < 24-hour old individuals, which are recommended. 

In the chronic study with D. magna (MRID 43116601), the NOAEC of 0.0337 μg a.i./L was 

based on survival. 

Since the freshwater invertebrate chronic toxicity endpoint of 0.0337 μg/L (D. magna; MRID 

43116601) was not generated using the most acutely sensitive freshwater invertebrate (i.e., G. 

lacustris), a chronic toxicity endpoint for G. lacustris of 0.0127 μg/L was calculated using the 

acute toxicity endpoint for G. lacustris and an ACR for D. magna (see Table 5-1 for 

calculation). 

5.1.4 Estuarine/Marine Invertebrates 

Based on studies with pink shrimp and Eastern oyster (MRID 40228401), coumaphos is highly 

to very highly toxic to estuarine/marine invertebrates on an acute basis. These studies yielded 

EC50 endpoints of 2.0 and 290 μg a.i./L, respectively. 

No data are available for the chronic toxicity of coumaphos to estuarine/marine invertebrates. 

Therefore, a chronic toxicity endpoint for estuarine/marine invertebrates of 0.3421 μg/L was 

calculated using the acute toxicity endpoint for pink shrimp and an ACR for freshwater 

invertebrates (i.e., D. magna) (see Table 5-1 for calculation). 

5.1.5 Benthic (Sediment-Dwelling) Invertebrates 

No data are available for the toxicity of coumaphos to benthic invertebrates. 
47 

5.1.6 Aquatic Plants 

A Tier II study with Lemna gibba (MRID 43822801) submitted since the 2008 problem 

formulation yielded no effects resulting in an EC50 and NOAEC of > 166 and 166 μg a.i./L, 

respectively. This study was classified as “supplemental” due to the number of plants per 

replicate being lower than recommended. 

No acceptable data are available for the toxicity of coumaphos to aquatic non-vascular plants. 

As noted previously, a study with P. subcapitata (MRID 48322802) submitted since the 2008 

problem formulation was classified as “invalid” because the solvent had a stimulatory effect that 

could have masked the true effects of coumaphos. An EFED memo (DP 406398, October 31, 

2012) proposed using data from a surrogate pesticide in lieu of requesting an additional nonvascular aquatic plant study. Specifically, the memo noted that aquatic non-vascular plant data 

are available for the following organophosphate insecticides: chlorpyrifos, diazinon, dichlorvos, 

dicrotophos, dimethoate, EPN, fenthion, naled, oxydemeton-methyl, phorate, and trichlorfon. Of 

the available data, naled is the most toxic to aquatic non-vascular plants. Thus, toxicity data for 

naled (Table 5-2) was used for characterizing the toxicity of coumaphos to aquatic non-vascular 

plants. The most sensitive definitive toxicity endpoints for naled (i.e., EC50 = 24 μg a.i./L; 

NOAEC = 4.2 μg a.i./L) are bolded. 

Table 5-2. Aquatic Plant Toxicity Profile for Naled 

Species % a.i. Toxicity Valuesa Source & 

Classification 

Duckweed 

(Lemna gibba) 94.4 14-day EC50 > 1800 μg a.i./L 14-day NOAEC < 1800 μg a.i./L 

MRID 42529601 

Supplemental 

Blue-green algae 

(Anabaena flos-aquae) 94.4 5-day EC50 (95% C.I.) = 91 (15-7400) μg a.i./L 5-day NOAEC = 57 μg a.i./L 

MRID 42529604 

Acceptable 

Freshwater diatom 

(Navicula pelliculosa) 94.4 5-day EC50 (95% C.I.) = 24 (10-70) μg a.i./L 5-day NOAEC = 4.2 μg a.i./L

MRID 42529603 

Acceptable 

Green algae 

(Selenastrum 

capricornutum)

94.4 

5-day EC50 (95% C.I.) = 40 (13-100) μg a.i./L 

5-day NOAEC: Not reported MRID 42529605 

Acceptable 

Marine diatom 

(Skeletonema costatum) 94.4 5-day EC50 (95% C.I.) = 50 (24-100) μg a.i./L 5-day NOAEC = 6.3 μg a.i./L 

MRID 42529602 

Acceptable 

C.I. = confidence interval 

a BOLD values used in risk characterization 

5.2 Effects to Terrestrial Organisms 

Summaries of data used to characterize the effects of coumaphos to terrestrial organisms are 

provided in Table 5-3. The most sensitive definitive toxicity endpoints used in RQ calculations 

are bolded. 
48 

Table 5-3. Endpoints Used to Characterize the Effects of Coumaphos to Terrestrial Organisms 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpoints1,2 (Effects) & Acute Toxicity Classi

(if applicable) 

Survival, growth, and reproduction of birds (surrogate for reptiles and terrestrial-phase amphibians) 

Most sensitive avian acute oral LD50

98.25 Bobwhite quail 

(Colinus virginianus) 

14-day LD50 (95% C.I.)= 2.4 (1.1-3.3) mg a.i./kg-bw (nom

Probit slope (95% C.I.) = 4.3 (1.2-7.3)  (0, 40, 100, 100, and 100% mortality at 2, 4, 8, 16, 32 mg bw; all mortality occurred within the first 24 hours; subletheffects: fluffed feathers in some birds of the 2 mg a.i./kg-btreatment group; salivation, ataxia, wing drop, convulsionsfluffed feathers in other treatment groups) Very highly toxic 

95 Ring-necked 

peasant (Phasianus colchicus) 

14-day LD50 (95% C.I.) = 7.94 (5.73-11.0) mg a.i./kg-bw (

females (mortality 2-3 hr after treatment; remission took up to 14 dsublethal effects: spraddle-legged walking, wing twitchingslowness, hypoactivity, ataxia, wing-drop, falling, nutationprostration with wings spread, lacrimation, immobility, wiconvulsions, and tetany appearing as soon as 90 minutes) Very highly toxic 

95 Mallard duck 

(Anas platyrhynchos) 

14-day LD50 (95% C.I.) = 29.8 (21.5-41.3) mg a.i./kg-bw 

males (mortality 2-3 hr after treatment; remission took up to 14 dsublethal effects: spraddle-legged walking, wing twitchingslowness, hypoactivity, ataxia, wing-drop, falling, nutationprostration with wings spread, lacrimation, immobility, wiconvulsions, and tetany appearing as soon as 40 minutes) Highly toxic 

Most sensitive avian sub-acute dietary LC50

98.25 Bobwhite quail 

(Colinus virginianus) 

8-day LC50 (95% C.I.) = 82.1 (67.6-99.7) mg a.i./kg-diet (

Probit slope (95% C.I.) = 6.6 (3.6-9.7)  (0, 10, 20, 70, 100, 100, and 100% mortality at 30, 45, 68153, 230, and 345 mg a.i./kg-diet; sublethal effects: ataxiadrop, convulsions, tremors, and diarrhea at ≥ 68 mg a.i./kg

decrease in body weights at 45-153 mg a.i./kg-diet; concendependent decrease in food consumption during the first 5 birds on treated feed) Highly toxic 

95 Bobwhite quail 

(Colinus virginianus) 

8-day LC50 (95% C.I.) = 120 (104-139) mg a.i./kg-diet (no

Probit slope (S.D.) = 7.348 (1.923) Highly toxic 

95 Japanese quail 8-day LC50 (95% C.I.) = 225 (172-306) mg a.i./kg-diet (no
49 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpoints1,2 (Effects) & Acute Toxicity Classi

(if applicable) 

(Coturnix japonica) 

Probit slope (S.D.) = 4.652 (1.049) Highly toxic 

95 Ring-necked 

peasant (Phasianus colchicus) 

8-day LC50 (95% C.I.) = 318 (227-364) mg a.i./kg-diet (no

Probit slope (S.D.) = 7.228 (1.452) Highly toxic 

98.25 Mallard duck 

(Anas platyrhynchos) 

8-day LC50 (95% C.I.) = 402 (227-593) mg a.i./kg-diet (no

Probit slope (95% C.I.) = 2.9 (1.7-4.2)  (0, 0, 30, 50, 70, and 100% mortality at 50, 100, 200, 400and 1600 mg a.i./kg-diet; sublethal effects wing drop, salivregurgitation, ataxia, nutation, and immobility at ≥ 200 mg diet; decrease in body weights from day 0 to day 5 at ≥ 10a.i./kg-diet; concentration-dependent decrease in food consumption during the first 5 days for birds on treated feeHighly toxic 

95 Mallard duck 

(Anas platyrhynchos) 

8-day LC50 (95% C.I.) = 709 (521-1032) mg a.i./kg-diet (n

Probit slope (S.D.) = 1.981 (0.933) Moderately toxic 

Most sensitive avian chronic NOAEC No data 

Survival, growth, and reproduction of mammals 

Most sensitive mammalian acute LD50

TGAI SpragueDawley rat 

(Rattus norvegicus) 

Females LD50 (95% C.I.) = 17 (14-22) mg/kg-bw 

Male LD50 > 240 mg/kg-bw 

(Mortality: females – 0, 0, 70, and 100% mortality at 5, 10and 40 mg/kg-bw; males – 0, 0, 0, 0, and 10% mortality at 30, 60, 120, and 240 mg/kg-bw; sublethal effects (not spefemales – 90, 100, 100, and 100% at 5, 10, 20, and 40 mg/males – 80, 100, 100, 100, 100, and 100% at 7.5, 15, 30, 6and 240 mg/kg-bw ) Highly toxic 

Most sensitive mammalian chronic NOAEC 

99 SpragueDawley rat 

(Rattus norvegicus) 

Two-generation reproduction Cholinesterase (ChE) inhibition 

NOAEL = 1 mg/kg-diet (0.07 mg/kg-bw/day) LOAEL = 5 mg/kg-diet (0.30 mg/kg-bw/day) Systemic/reproductive toxicity NOAEC = 25 mg/kg-diet (1.79 mg/kg-bw/day) LOAEC > 25 mg/kg-diet (1.79 mg/kg-bw/day) (no effects) 
50 

Assessment Endpoint 

Measurement Endpoint 

% a.i. Species Toxicity Endpoints1,2 (Effects) & Acute Toxicity Classi

(if applicable) 

Survival, growth, and reproduction of non-target terrestrial invertebrates 

Most sensitive terrestrial invertebrate (e.g., honey bee) acute LD50

See Section 5.2.3

Survival, growth and reproduction of terrestrial plants 

Seedling emergence: Most sensitive monocot and dicot EC25 and NOAEC 

No data 

Vegetative vigor: Most sensitive monocot and dicot EC25 and NOAEC 

No data 

NS = not specified; C.I. = confidence interval 1 BOLD values used in RQ calculations 2 nom = nominal 
51 

5.2.1 Birds 

Based on studies with bobwhite quail, ring-necked peasant, and mallard duck, coumaphos is 

highly toxic to very highly toxic to birds on an acute oral basis. 

In the acute oral study with bobwhite quail (MRID 00112843), the LD50 was 2.4 mg a.i./kg-bw, 

and all mortality occurred within the first 24 hours. Sublethal effects in the lowest treatment 

group of 2 mg a.i./kg-bw (100% survival) included fluffed feathers in some birds. Salivation, 

ataxia, wing drop, convulsions, and fluffed feathers were observed in the other treatment groups. 

In acute oral studies with ring-necked peasant and mallard duck (MRID 01600000), the LD50’s 

were 7.97 and 29.8 mg a.i./kg-bw, respectively. Mortality occurred within 2 to 3 hours after 

treatment, and remission took up to 14 days. Sublethal effects including spraddle-legged 

walking, wing twitching, slowness, hypoactivity, ataxia, wing-drop, falling, nutation, prostration 

with wings spread, lacrimation, immobility, wing-beat convulsions, and tetany appeared as soon 

as 90 and 40 minutes after dosing in ring-necked peasants and mallard ducks, respectively. 

Based on studies with bobwhite quail, Japanese quail, ring-necked pheasant, and mallard duck, 

coumaphos is moderately to highly toxic to birds on a sub-acute dietary basis. 

In the sub-acute dietary study with bobwhite quail that yielded the most sensitive endpoint 

(MRID 00112843), the LC50 was 82.1 mg a.i./kg-diet. Sublethal effects included ataxia, wing 

drop, convulsions, tremors, and diarrhea at ≥ 68 mg a.i./kg-diet and a decrease in body weights at 

45-153 mg a.i./kg-diet. A concentration-dependent decrease in food consumption was also 

observed during the first 5 days for birds on treated feed. 

In sub-acute dietary studies with bobwhite quail, Japanese quail, and mallard duck (MRID 

00022923), the LC50’s were 120, 225, and 709 mg a.i./kg-diet. Sublethal effects were not 

specified for these studies. 

In another sub-acute dietary study with mallard duck (MRID 00112842), the LC50 was 402 mg 

a.i./kg-diet. Sublethal effects included wing drop, salivation, regurgitation, ataxia, nutation, and 

immobility at ≥ 200 mg a.i./kg-diet and a decrease in body weights from day 0 to day 5 at ≥ 100 

mg a.i./kg-diet. A concentration-dependent decrease in food consumption was also observed 

during the first 5 days for birds on treated feed. 

There are no data available for the chronic, reproductive toxicity of coumaphos to birds. In the 

absence of data specific to coumaphos, avian chronic toxicity data for surrogate organophosphate 

insecticides – specifically phosphorothioates – were used to characterize the chronic toxicity of 

coumaphos to birds. Phosphorothionate were selected because they are most likely to have 

physico/physiochemical properties that are similar to those of coumaphos. Avian chronic, 

reproductive toxicity data are available for the following phosphorothionate insecticides: 

fenitrothion, methyl parathion, and parathion (Table 5-4). Of the available data, parathion is the 

most toxic to birds on a chronic basis. Thus, the most sensitive chronic avian toxicity endpoint 

for parathion (i.e., NOAEC = 2.85 mg/kg-diet) was used for characterizing the chronic toxicity 

of coumaphos to birds. 
52 

Table 5-4. Toxicity Data for Surrogate Organophosphorothionate Insecticides 

Chemical 

PC Code

Species NOAECa

(mg/kg-diet)

MRID & Classification 

Fenitrothion 

105901

Bobwhite quail 

(Colinus virginianus) 13 41958401 Acceptable 

Mallard duck 

(Anas platyrhynchos) 40 00262755 

Acceptable 

Methyl parathion 

53501

Bobwhite quail 

(Colinus virginianus) 6.3 41179302 Acceptable 

Mallard duck 

(Anas platyrhynchos) 14.7 41179301 Supplemental 

Parathion 

57501

Bobwhite quail 

(Colinus virginianus) 8 41133102 Supplemental 

Mallard duck 

(Anas platyrhynchos) 2.85 41133101 Acceptable a BOLD value used in risk characterization 

5.2.2 Mammals 

Based on a study with rat, coumaphos is highly toxic to mammals on an acute oral basis. In this 

acute oral study with rats (MRID 00110597), females were the more sensitive sex with an LD50

of 17 mg/kg-bw. Sublethal effects were not specified. 

In a rat two-year generation reproduction study (MRID 43061701), cholinesterase inhibition was 

observed at 5 and 25 ppm and was manifested as dose-dependent decreases in erythrocyte (RBC) 

and plasma cholinesterase (ChE). Relative to concurrent controls, RBC ChE was inhibited 31-

70% at 5 ppm and 53-95% at 25 ppm. Generally, no differences were noted between Day 47 (or 

56) and Day 91 ChE levels. Brain levels were significantly inhibited (30%) in FO and F1 females. 

In pups, plasma and RBC ChE levels were inhibited (31-44%) at 25 ppm on lactation day 21 but 

not on lactation day 4. Based on these results, the NOAEL and LOAEL for ChE inhibition were 

1 and 5 ppm, respectively. There were no other signs of systemic toxicity. The NOAEL and 

LOAEL for systemic toxicity were equal to and greater than 25 ppm, respectively. Reproductive 

toxicity was not observed in this study. Consequently, the NOAEL for reproductive toxicity was 

25 ppm, and the LOAEL for reproductive toxicity was greater than 25 ppm. 

5.2.3 Non-Target Terrestrial Invertebrates 

Data from guideline studies with honey bees are not available. However, three registrantsubmitted studies evaluating the efficacy of coumaphos-impregnated strips to control mites in 

honey bee hives in Guatemala (MRID 45752811), Minnesota (MRID 45752812), and Nebraska 

(MRID 45752810) as well as an abstract of published research describing the control of the small 

hive beetles in hives treated with coumaphos-impregnated strips (MRID 45752813) have been 

reviewed and classified as “supplemental” (Table 5-5). In general, coumaphos was efficacious 

when impregnated strips contained a concentration of 5 or 10% active ingredient. It should be 

noted that in the three varroa mite efficacy studies, fluvalinate (formulated into Apistan strips) 

was used following treatment with coumaphos strips and in control groups but had no apparent 

effect on mite control. 
53 

In one of the varroa mite studies (MRID 45752812), bee mortality was quantified and did not 

appear to be different between control and treated hives (Table 5-5). In the other two varroa 

mite studies, the study authors stated that no unusual bee mortality was observed following 

treatment with coumaphos strips without further quantification (duration: 37-46 days; MRIDs 

47572810 and 47572811). Bee mortality was not reported in the small hive beetle study 

(duration: 72 hours; MRID 45752812). These studies were not designed to measure other 

endpoints related to hive health and long-term effects (following the treatment period). Thus, 

there is uncertainty regarding the effects of coumaphos on brood, as well as the long-term 

stability of the hive. 

Table 5-5. Summary of Observations of the Effect of Coumaphos on Bees Obtained from 

Efficacy Studies

Study Type Species Summary Source & 

Classification 

Non-guideline: Efficacy of 

Coumaphos Impregnated Strips 

for the Control of Varroa Mite 

Honey bee 

(Apis 

mellifera) 

No unusual bee mortality or injury to the 

colonies was observed during treatment (37 

days) with coumaphos strips. 

MRID 45752810 

Supplemental 

Non-guideline: Efficacy of 

Coumaphos Impregnated Strips 

for the Control of Varroa Mite 

Honey bee 

(Apis 

mellifera) 

No unusual adult bee mortality was observed 

during treatment (46 days) with the 

coumaphos strips. 

MRID 45752811 

Supplemental 

Non-guideline: Efficacy of 

Coumaphos Impregnated Strips 

for the Control of Varroa Mite 

Honey bee 

(Apis 

mellifera) 

No unusual bee mortality or injury to the 

colonies was observed during treatment (46 

days, but only 36 days of bee mortality 

observations) with coumaphos strips (control 

group: 329 dead bees, 2.5% group: 348 dead 

bees, 5% group = 373 dead bees, 10% group: 

319 dead bees). However, six colonies died 

due to starvation (one in control, two in 2.5% 

coumaphos treatment, two in 5% coumaphos 

treatment, and one in 10% coumaphos 

treatment). 

MRID 45752812 

Supplemental 

Non-guideline: Efficacy of 

Coumaphos Impregnated Strips 

for the Control of Small Hive 

Beetle 

Honey bee 

(Apis 

mellifera) 

No reports were made regarding observations 

of bee mortality or hive health during 

treatment (72 hours). 

MRID 45752813 

Supplemental 

Data on the effects of coumaphos on the survival, growth, and/or reproduction of honey bees 

(Apis mellifera) are available from five open literature studies as identified via ECOTOX17

(Table 5-6). 

Table 5-6. Summary of Observations of the Effect of Coumaphos on Bees Obtained from 

Open Literature Studies as Identified via ECOTOX

Study Type Species Route of Exposure & Toxicity Values ECOTOX No. 

& Classification 

Non-guideline: Effects of 

coumaphos on queen rearing 

Honey bee 

(Apis 

mellifera) 

Impregnated strips 

Not applicablea

E066848 

Qualitative 

 

17 http://cfpub.epa.gov/ecotox/
54 

Study Type Species Route of Exposure & Toxicity Values ECOTOX No. 

& Classification 

Non-guideline: Effects of 

coumaphos on queen rearing 

Honey bee 

(Apis 

mellifera) 

Beeswax in queen cups 

10-day NOAEC = 10 mg/kg 

10-day LOAEC = 100 mg/kg 

(based on rejection of transferred larvae and 

reduced weight of queen pupae) 

E100380 

Quantitative 

Non-guideline: Effects of 

coumaphos on queen rearing 

Honey bee 

(Apis 

mellifera) 

Beeswax in queen cups 

10-day NOAEC = 10 mg/kg 

10-day LOAEC = 100 mg/kg 

(based on rejection of transferred larvae and 

reduced weight of queen pupae) 

E100910 

Quantitative 

Non-guideline: Acute and chronic 

toxicity of coumaphos (as well as 

effects of coumaphos on 

hemolymph volume and Nosema

infection) in the laboratory 

Honey bee 

(Apis 

mellifera) 

Oral 

48-hr LD50 = 2.99 μg/bee for 8 day old bees 

48-hr LD50 = 3.10 μg/bee for 14 day old bees 

48-hr LD50 = 6.04 μg/bee for 3 day old bees 

E101175 

Quantitative 

Non-guideline: Synergistic 

interactions of coumaphos and 

tau-fluvalinate in the laboratory 

Honey bee 

(Apis 

mellifera) 

Contact (application to thorax) 

24-hr LD50 = 20.39 μg/bee 

E119503 

Qualitative 

a

 There were only 2 treatment groups, and effects were seen in both groups relative to the control. Therefore, it was 

not possible to establish NOAECs or concentration-response relationships. 

Three of the studies evaluated the effects of coumaphos on queen rearing. In E066848, honey 

bee colonies were treated with coumaphos-impregnated strips and monitored in two separate 

experiments (see Section 4.3.4 for additional experimental details). There was high mortality in 

developing queens in colonies treated with ≥ 1 coumaphos strips for more than 24 hours. 

Physical abnormalities and atypical behavior were observed in queens due to inclusion of 

coumaphos strips in colonies. Queen weights and ovary weights were also significantly lower in 

treatment groups than the control group. Coumaphos concentrations increased in the bees and 

wax after treatments (see Section 4.3.4 for concentrations). This study was classified as 

“qualitative” for use in the assessment because only two treatment groups were assessed, and 

effects were seen in both groups relative to the control. Therefore, it was not possible to 

establish NOAECs or concentration-response relationships. 

In E100910, young honey bee larvae were transferred into queen cups containing 0 (control), 1, 

10, 100, 300, 600, and 1000 mg/kg coumaphos. The cups with larvae were then placed in 

queenless colonies and examined after 10 days to determine the rejection rate of transferred 

larvae and weight of queen pupae. At ≥ 100 mg/kg, there was a significant rejection of larvae 

compared to control larvae. In addition, there was a significant reduction in the weight of queen 

pupae at 100 mg/kg compared to the control after 10 days. The 1 and 10 mg/kg treatment groups 

were not significantly different than the control for either endpoint. This study was classified as 

“quantitative” for use in the assessment. 

In E100380, young honey bee larvae were transferred into queen cups containing 0 (control), 1, 

10, 100, and 1000 mg/kg coumaphos. The cups with larvae were then placed in queenless 

colonies and examined after 10 days to determine the rejection rate of transferred larvae and 

weight of queen pupae. The queen cells were then placed in small mating colonies and 
55 

examined after 21 days to determine commercial acceptability and mating success based on 

sperm count. Finally, the queens were introduced to production colonies and monitored for six 

months. For rejection rate and weight of queen pupae, significant effects were observed in the 

100 and 1000 mg/kg coumaphos treatment groups when compared to the control. The 1 and 10 

mg/kg treatment groups were not significantly different than the control for either endpoint. 

Mean sperm count was not significantly different among the control and 1, 10, and 100 mg/kg 

treatment groups, although there were significant differences between spermatheca color groups. 

Although not statistically significant, the percentage of queens from the 100 mg/kg treatment 

group surviving for 2-6 months in the production colony was less than that of queens from the 

control and 10 mg/kg treatment group. This study was classified as “quantitative” for use in the 

assessment. 

One study (E119503) evaluated the effects of coumaphos and the pyrethroid tau-fluvalinate 

administered individually and in combination via contact exposure. Specifically, 3 to 4 day old 

worker bees were treated with 0 (solvent control), 0.1, 0.3, 1, 3, and 10 μg/bee via application to 

the thorax with or without pretreatment with enzyme inhibitors DEM, DEF, or PBO or taufluvalinate. Mortality was recorded 24 hours after treatment. The LD50 of coumaphos in the 

absence of enzyme inhibitors was 20.39 μg/bee. DEM did not alter the toxicity of coumaphos, 

but DEF and PBO enhanced the toxicity of coumaphos by 2.8-fold and 4-fold, respectively. 

When tau-fluvalinate was used as a pretreatment, the toxicity of coumaphos increased by 3.4-

fold. This study was classified as “qualitative” for use in the assessment because the 

experimental design included a solvent control group but did not include a negative control 

group. 

 

One study (E101175) examined the toxicity of coumaphos from acute oral and chronic 

exposures. For the acute toxicity tests, 3, 8, or 13 day old bees were fed 10 μL of 0.79 M 

sucrose solution containing 0, 0.8, 1.6, 3.2, 4.8, 6.4, or 8.0 μg coumaphos. Mortality was 

recorded 16, 24, 32, and 48 hours after feeding. For the chronic toxicity test, mixed age bees 

were fed a 2% coumaphos solution for 7 days, and mortality was recorded. Only a few bees fed 

coumaphos survived up to 12, 16, and 24 hours in the acute toxicity tests. The LD50 for 3 day 

old bees was 6.04 μg/bee, whereas the LD50’s for 8 and 14 day old bees were 2.99 and 3.10 

μg/bee, respectively. During chronic exposure, bees showed 50% mortality at day 7, which 

corresponded to 3 μg/bee/day. This study was classified as “quantitative” for use in the 

assessment. 

5.2.4 Terrestrial (Upland and Semi-Aquatic) Plants 

No data are available for the toxicity of coumaphos to terrestrial plants. Terrestrial plant toxicity 

data are available for the following organophosphate insecticides: diazinon, disulfoton, 

fosthiazate, isofenfos, and profenofos (see USEPA, 2010 for discussion of data). Of the 

available data, profenofos is the most toxic to terrestrial plants. Thus, toxicity data for 

profenofos (Table 5-7) was used for characterizing the toxicity of coumaphos to terrestrial 

plants. 

Table 5-7. Terrestrial Plant Toxicity Data for Profenofos 

Study Type Toxicity Endpoints Source 

Seedling emergence Most sensitive monocot: None MRID 41627307 
56 

Study Type Toxicity Endpoints Source 

Tier 2 EC25 > 1 lb a.i./A 

NOAEC = 1 lb a.i./A 

Most sensitive dicot: Cucumber (Cucumis sativus) 

EC25 = 0.13 lb a.i./A 

NOAEC = 0.111 lb a.i./A 

Acceptable 

Vegetative vigor 

Tier 2 

Most sensitive species: None (4 monocots and 6 dicots) 

EC25: Could not be determined due to lack of concentration response 

NOAEC = 1.0 lb a.i./A 

MRID 41627305 

Acceptable 

5.3 Incident Database Review 

Reviews of the Ecological Incident Information System (EIIS, version 2.1.1), which is 

maintained by the Agency’s Office of Pesticide Programs, and the Avian Monitoring 

Information System (AIMS), which is maintained by the American Bird Conservatory, on May 

31, 2013 yielded incidents involving terrestrial animals. 

Two of the incidents involved birds: 

 In a letter dated January 7, 1983, the U.S. Fish and Wildlife Service (USFWS) reported 

an unknown number of American wigeon(s) (Anas americana) was found dead in 

November 1981 in Washington state near a pond adjacent to a feedlot (EIIS B0000-400-

27 and AIMS). The cause of death was attributed to coumaphos. However, information 

on the exposure pathway was not provided. 

 The Canadian Wildlife Service and USFWS reported that one bald eagle (Haliaeetus 

leucocephalus) was observed dead or dying in Natrona County, Wyoming on March 2, 

1986 (AIMS). Investigators were certain that coumaphos was responsible for this 

incident based on detection of coumaphos in gut contents and quantification of brain 

cholinesterase activity. 

The remaining incidents involved honey bees: 

 Eight kills of honey bees (Apis mellifera) from September 2001 to September 2002 were 

reported by the Minnesota Department of Agriculture (EIIS I014202-02, I014202-03, 

I014202-04, I014202-05, I014202-07, I014202-08, I014202-09, I014202-17). In all of 

these incidents, residue analyses detected coumaphos in bee tissue and/or pollen. No 

other pesticides were detected. Investigators concluded that insufficient evidence was 

available to determine if the exposure to coumaphos played a role in these bee kills or 

was merely incidental. 

 In June 2009, after the aerial application of the active ingredients carbaryl, potassa, 

fenoxaprop-ethyl to crop fields in Box Elder County, UT, 30% of the bee hives (Apis 

mellifera) died within a month (EIIS I021587-001). Subsequently, there were 3 more 

applications at bloom with Warrior (active ingredient: 22.8% lambda-cyhalothrin) 

through August. By December of 2009, 320 hives collapsed. Lab testing detected 14 

different active ingredients including coumaphos in bee tissue and/or bee wax. 

In addition to the incidents recorded in EIIS and AIMS, additional incidents are reported to the 

Agency in aggregated form. Pesticide registrants report certain types of incidents to the Agency 

as aggregate counts of incidents occurring per product per quarter. Ecological incidents reported 
57 

in aggregate reports include those categorized as ‘minor fish and wildlife’ (W-B), ‘minor plant’ 

(P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ incidents include reports of 

adverse effects to insects and other terrestrial invertebrates. For coumaphos, registrants have 

reported no minor fish and wildlife incidents, no minor plant incidents, and one other non-target 

incident as of June 4, 2013. The minor other non-target incident involved the use of Checkmite 

(bee strip). 

The total number of actual incidents associated with the use of coumaphos may be higher than 

what is reported to the Agency. Incidents may go unreported since effects may not be 

immediately apparent and/or readily attributed to the use of a chemical. 
58 

6 Risk Characterization 

6.1 Risk Estimation 

Estimates of exposure and toxicity of coumaphos are integrated using standard risk quotient 

(RQ) methods to evaluate the potential for adverse ecological effects to mammalian, avian, 

aquatic, and other non-target species. RQ results for non-target terrestrial and aquatic animals 

and plants are described in this section and represent expected direct effects to organisms (i.e., 

effects from direct toxicity to coumaphos exposure) in contrast to indirect effects to organisms 

resulting from a modification of a resource such as loss of their prey or habitat. 

6.1.1 Direct Effects to Aquatic Organisms 

Risk to aquatic organisms from exposure via runoff (CAFO manure applied to land, nonregulated small CAFO, rangeland) was estimated using EECs from PRZM/EXAMS modeling. 

Risk to aquatic organisms from exposure via wash-off from the skin of treated livestock that 

enter bodies of water was estimated in two ways. First, RQs for wash-off from one cow entering 

a 1 acre, 6 foot deep body of water were calculated using EECs in Tables 4-8 and 4-10 (i.e., 

EEC/cow) and the following formula: 

RQ/cow = (EEC/cow in μg/L) / (Toxicity endpoint in μg/L) 

Second, the number of cows entering a 1 acre, 6 foot deep body of water that would cause an 

LOC exceedance was calculated using the following formula: 

Number of cows to cause LOC exceedance = LOC / (RQ/cow) 

6.1.1.1 Fish and Aquatic-Phase Amphibians 

Freshwater fish acute RQs were calculated using the most sensitive acute toxicity endpoint of 

340 μg/L (bluegill sunfish; MRID 40098001); freshwater fish chronic RQs were calculated using 

an estimated chronic toxicity endpoint (for bluegill sunfish) of 4.4 μg/L (Tables 6-1 and 6-2). 

Freshwater fish acute and chronic RQs for runoff range are <0.01 and <0.01 to 0.05 respectively. 

There are no freshwater fish acute or chronic LOC exceedances for runoff. 

Freshwater fish acute and chronic RQs for wash-off from one cow entering a 1 acre, 6 foot deep 

body of water are <0.01. Hundreds of cows would need to enter a 1 acre, 6 foot deep body of 

water to cause an acute or chronic LOC exceedance for freshwater fish. 

 
59 

Table 6-1. Freshwater Fish Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

Texas: Spray Application (42% flowable concentrate)

BSSTurf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.02 <0.01 0.01 

Runoff from non-regulated small CAFO 0.02 <0.01 0.04 

RangeBSS Runoff from rangeland 0.02 <0.01 <0.01 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

PA Turf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.027 <0.01 0.01 

Runoff from non-regulated small CAFO 0.027 <0.01 0.05 

Runoff from rangeland 0.027 <0.01 <0.01 

6-2. Freshwater Fish Risk Quotients (RQs) for Wash-Off from Treated Livestock That 

Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fraction 

Acute 

RQ/cow 

Number of Cows to 

Cause Acute LOC 

Exceedance 

Chronic 

RQ/cow 

Number of Cows to 

Cause Chronic 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow 

hide) 

Listed NonListed Listed & NonListed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 <0.01 1308 13077 <0.01 550 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 <0.01 2429 24286 <0.01 1100 

 

Estuarine/marine fish acute RQs were calculated using the most sensitive acute toxicity endpoint 

of 280 μg/L (sheepshead minnow; MRID 40228401); estuarine/marine fish chronic RQs were 

calculated using an estimated chronic toxicity endpoint (for sheepshead minnow) of 3.6 μg/L 

(Table 6-3 and 6-4). 

Estuarine/marine fish acute and chronic RQs for runoff are <0.01 and <0.01 to 0.06, respectively. 

There are no estuarine/marine fish acute or chronic LOC exceedances for runoff. 

Estuarine/marine fish acute and chronic RQs for wash-off from one cow entering a 1 acre, 6 foot 

deep body of water are <0.01. Hundreds of cows would need to enter a 1 acre, 6 foot deep body 

of water to cause an acute or chronic LOC exceedance for estuarine/marine fish. 

Table 6-3. Estuarine/Marine Fish Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

Texas: Spray Application (42% flowable concentrate)

BSSTurf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.02 <0.01 0.01 

Runoff from non-regulated small CAFO 0.02 <0.01 0.05 

RangeBSS Runoff from rangeland 0.02 <0.01 <0.01 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

PA Turf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.027 <0.01 0.01 

Runoff from non-regulated small CAFO 0.027 <0.01 0.06 
60 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

Runoff from rangeland 0.027 <0.01 <0.01 

Table 6-4. Estuarine/Marine Fish Risk Quotients (RQs) for Wash-Off from Treated 

Livestock That Enter Bodies of Watera 

Maximum Application Rate Wash-Off 

Fraction 

Acute 

RQ/cow 

Number of Cows to 

Cause Acute LOC 

Exceedance 

Chronic 

RQ/cow 

Number of Cows 

to Cause Chronic 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow 

hide) 

Listed NonListed Listed & NonListed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 <0.01 1077 10769 <0.01 450 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 <0.01 2000 20000 <0.01 900 

a

 1 acre, 6 foot deep body of water 

6.1.1.2 Aquatic Invertebrates 

Freshwater invertebrate acute RQs were calculated using the most sensitive acute toxicity 

endpoint of 0.074 μg/L (G. lacustris; MRIDs 05009242 and 40098001); freshwater invertebrate 

chronic RQs were calculated using an estimated chronic toxicity endpoint (for G. lacustris) of 

0.0127 μg/L (Table 6-5 and 6-6). 

Freshwater invertebrate acute and chronic RQs for runoff range from 0.02 to 3.4 and 0.09 to 17, 

respectively. There are multiple acute and chronic exceedances across runoff exposure pathways 

for both Texas and the rest of the U.S. 

Freshwater invertebrate acute RQs for wash-off from one cow entering a 1 acre, 6 foot deep 

body of water are 0.11 and 0.05 for Texas and the rest of the U.S., respectively, whereas chronic 

RQs for wash-off from one cow entering a 1 acre, 6 foot deep body of water are 0.63 to 0.31 for 

Texas and the rest of the U.S., respectively. Only one and five to ten cows would need to enter a 

1 acre, 6 foot deep body of water to cause acute LOC exceedances for listed and non-listed 

freshwater invertebrates, respectively. Only two and four cows would need to enter the same 

body of water to cause a chronic LOC exceedance for freshwater invertebrates in Texas and the 

rest of the U.S., respectively. 

Table 6-5. Freshwater Invertebrate Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

Texas: Spray Application (42% flowable concentrate; 3 applications @ 0.021 lb/AU)

BSSTurf Runoff from CAFO manure applied to land No incorporation of manure into soil 

0.02 0.68** 2.4*** 

Incorporation of manure into soil within a day 

0.02 0.04 0.17

Runoff from non-regulated small CAFO 0.02 3.4** 17*** 

RangeBSS Runoff from rangeland 0.02 0.07* 0.31

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration; 6 applications @ 0.00829 lb/AU)

PA Turf Runoff from CAFO manure applied to land No incorporation of manure into soil 
61 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

0.027 0.54** 2.4*** 

Incorporation of manure into soil within a day

0.027 0.03 0.14

Runoff from non-regulated small CAFO 0.027 3.9** 18*** 

Runoff from rangeland 0.027 0.02 0.09 

*exceeds aquatic animal acute listed species LOC (=0.05) 

**exceeds aquatic animal acute non-listed species LOC (=0.5) 

*** exceeds aquatic animal chronic listed and non-listed species LOC (=1) 

Table 6-6. Freshwater Invertebrate Risk Quotients (RQs) for Wash-Off from Treated 

Livestock That Enter Bodies of Watera 

Maximum Application Rate Wash-Off 

Fraction 

Acute 

RQ/cow 

Number of Cows to 

Cause Acute 

LOC Exceedance 

Chronic 

RQ/cow 

Number of Cows to 

Cause Chronic 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow 

hide) 

Listed NonListed Listed & 

Non-Listed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 0.11 <1 5 0.63 2 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 0.05 <1 10 0.31 4 

a

 1 acre, 6 foot deep body of water 

Estuarine/marine invertebrate acute RQs were calculated using the most sensitive acute toxicity 

endpoint of 2.0 μg/L (pink shrimp; MRID 40228401); estuarine/marine invertebrate chronic RQs 

were calculated using the estimated chronic toxicity endpoint (for pink shrimp) of 0.3421 μg/L 

(Table 6-7 and 6-8). 

Estuarine/marine invertebrate acute and chronic RQs for runoff range from <0.01 to 0.15 and 

<0.01 to 0.67, respectively. The only LOC exceedances are for acute exposure via runoff from 

non-regulated small CAFO for listed species of estuarine/marine invertebrates. 

Estuarine/marine invertebrate acute RQs for wash-off from one cow entering a 1 acre, 6 foot 

deep body of water are <0.01 for Texas and the rest of the U.S. whereas chronic RQs for washoff from one cow entering a 1 acre, 6 foot deep body of water are 0.02 to 0.01 for Texas and the 

rest of the U.S., respectively. Only 13 to 25 cows would need to enter a 1 acre, 6 foot deep body 

of water to cause acute LOC exceedances for listed estuarine/marine invertebrates whereas over 

a hundred cows would need to enter a 1 acre, 6 foot deep body of water to cause acute LOC 

exceedances for non-listed freshwater invertebrates. At least 43 and 86 cows would need to 

enter the same body of water to cause a chronic LOC exceedance for estuarine/marine 

invertebrates in Texas and the rest of the U.S., respectively. 

 
62 

Table 6-7. Estuarine/Marine Invertebrate Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

Acute RQ Chronic RQ 

Texas: Spray Application (42% flowable concentrate)

BSSTurf Runoff from CAFO manure applied to land No incorporation of manure into soil 

0.02 0.03 0.09

Incorporation of manure into soil within a day 

0.02 <0.01 0.01

Runoff from non-regulated small CAFO 0.02 0.13* 0.61

RangeBSS Runoff from rangeland 0.02 <0.01 0.01

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

PA Turf Runoff from CAFO manure applied to land No incorporation of manure into soil 

0.027 0.02 0.09

Incorporation of manure into soil within a day

0.027 <0.01 0.01

Runoff from non-regulated small CAFO 0.027 0.15* 0.67

Runoff from rangeland 0.027 <0.01 <0.01 

*exceeds aquatic animal acute listed species LOC (=0.05) 

6-8. Estuarine/Marine Invertebrate Risk Quotients (RQs) for Wash-Off from Treated 

Livestock That Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fraction 

Acute 

RQ/cow 

Number of Cows to 

Cause Acute LOC 

Exceedance 

Chronic 

RQ/cow 

Number of Cows 

to Cause Chronic 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow 

hide) 

Listed NonListed Listed & 

Non-Listed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 <0.01 13 125 0.02 43 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 <0.01 25 250 0.01 86 

a

 1 acre, 6 foot deep body of water 

Since no data are available for the toxicity of coumaphos to benthic (sediment-dwelling) 

invertebrates, acute and chronic RQs for benthic invertebrates (Tables 6-9 and 6-10) were 

calculated using the most sensitive water column acute and chronic toxicity endpoints for 

coumaphos (i.e., 0.074 and 0.0127 μg/L, respectively). 

Benthic invertebrate acute and chronic RQs for runoff range from 2.3 to 2.6 and 13 to 15, 

respectively. All benthic invertebrate RQs for runoff from a non-regulated small CAFO exceed 

LOCs. 

Benthic invertebrate acute RQs for wash-off from one cow entering a 1 acre, 6 foot deep body of 

water range from 0.04 to 0.07 whereas chronic RQs for wash-off from one cow entering a 1 acre, 

6 foot deep body of water range from 0.24 to 0.55. Less than 13 cows would need to enter a 1 

acre, 6 foot deep body of water to cause acute and chronic LOC exceedances for listed and nonlisted benthic invertebrates. 
63 

Table 6-9. Benthic Invertebrate Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off Fraction Acute RQ Chronic RQ 

Texas: Spray Application (42% flowable concentrate; 3 applications @ 0.021 lb/AU)

BSSTurf Runoff from non-regulated small CAFO 0.02 2.3** 13*** 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration; 6 applications @ 0.00829 lb/AU)

PA Turf Runoff from non-regulated small CAFO 0.03 2.6** 15*** 

**exceeds aquatic animal acute non-listed species LOC (=0.5) 

*** exceeds aquatic animal chronic listed and non-listed species LOC (=1) 

6-10. Benthic Invertebrate Risk Quotients (RQs) for Wash-Off from Treated Livestock 

That Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fraction 

Acute 

RQ/cow 

Number of Cows to 

Cause Acute LOC 

Exceedance 

Chronic 

RQ/cow 

Number of Cows 

to Cause Chronic 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow 

hide) 

Listed NonListed Listed & 

Non-Listed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 0.07 <1 8 0.55 2 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 0.04 <1 13 0.24 5 

a

 1 acre, 6 foot deep body of water 

6.1.1.3 Aquatic Plants 

RQs for aquatic non-vascular plants for exposure via runoff and wash-off were not calculated 

because of the lack of toxicity data specific to coumaphos. Risk to aquatic non-vascular plants 

from these exposure pathways is discussed in the Risk Description section of this document. 

RQs for listed aquatic vascular plants (Tables 6-11 and 6-12) were calculated with the toxicity 

endpoint of 166 μg/L (L. gibba; MRID 43822801). RQs for non-listed aquatic vascular plants 

were not calculated because the EC50 endpoint is non-definitive (i.e., >166 μg/L). 

Aquatic vascular plant RQs for runoff are all <0.01. Therefore, the listed aquatic plant LOC of 1 

is not exceeded for any runoff exposure pathways. 

Aquatic vascular plant RQs for wash-off from one cow entering a 1 acre, 6 foot deep body of 

water range are all <0.01. Thousands of cows would need to enter a 1 acre, 6 foot deep body of 

water to cause an LOC exceedance from wash-off for listed aquatic vascular plants. 

Table 6-11. Aquatic Vascular Plant Risk Quotients (RQs) for Runoff 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

RQs 

Listed Non-Listed 

Texas: Spray Application (42% flowable concentrate)

BSSTurf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.02 <0.01 

Not calculated Runoff from non-regulated small CAFO 0.02 <0.01 

RangeBSS Runoff from rangeland 0.02 <0.01 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)
64 

PRZM/EXAMS 

Scenarios 

Sources of a.i. 

from Application Scenario 

Wash-Off 

Fraction 

RQs 

Listed Non-Listed 

PA Turf Runoff from CAFO manure applied to land 

(No incorporation of manure into soil) 0.027 <0.01 

Not calculated Runoff from non-regulated small CAFO 0.027 <0.01 

Runoff from rangeland 0.027 <0.01 

Table 6-12. Aquatic Vascular Plants Risk Quotients (RQs) for Wash-Off from Treated 

Livestock That Enter Bodies of Watera 

Maximum Application Rate Wash-Off 

Fraction 

RQ/cow Number of Cows to Cause 

LOC Exceedance 

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow hide) 

Listed Non-Listed Listed Non-Listed 

Texas: Dip Vat Application (42% flowable concentrate)

Single 0.027 272 0.02 <0.01 Not calculated 20750 Not calculated 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.027 <0.01 Not calculated 41500 Not calculated 

a

 1 acre, 6 foot deep body of water 

6.1.2 Direct Effects to Terrestrial Organisms 

6.1.2.1 Birds, Reptiles, and Terrestrial-Phase Amphibians 

Avian acute RQs were calculated for three exposure pathways resulting from the application of 

coumaphos to livestock: 

 contact with/ingestion of hair and skin debris from treated cattle and/or contaminated soil 

and feed in and around treatment areas using dose-based EECs for treated cow hides (i.e., 

272 and 101 mg a.i./ft2 cow hide for Texas and the rest of the U.S., respectively) and 

dietary-based EECs of 370-1228 mg a.i./kg-diet; 

 ingestion of coumaphos-contaminated bird carcasses using dose- and dietary-based EECs 

for coumaphos intake via secondary ingestion (i.e., 1.17 x 10-6-3.87 x 10-5 mg a.i./gbw/day and 0.039-0.129 mg/g-diet, respectively); 

 ingestion of food items on land receiving manure from CAFOs using EECs from T-REX; 

and 

 ingestion of contaminated fish. 

To calculate acute dose-based RQs for the former (primary) exposure pathway, the most 

sensitive avian acute oral toxicity endpoint (i.e., LD50 = 2.4 mg/kg-bw for bobwhite quail; MRID 

00112843) was adjusted for the weight of the black-billed magpie (i.e., 186 g; Dunning, 1984), 

the species most likely to be exposed to coumaphos according to the pilot field study (MRID 

42512604), according to the formula provided in Table 6-13 and compared to the dose-based 

EECs of 272 and 101 mg a.i./ft2 cow hide for Texas and the rest of the U.S., respectively. Avian 

acute dose-based RQs for exposure via contact with/ingestion of hair and skin debris from 

treated cattle and/or contaminated soil feed in and around treatment areas are 609 and 226 for 

Texas and the rest of the U.S., respectively (Table 6-14). These acute dose-based RQs exceed 

the avian acute listed and non-listed species LOCs of 0.1 and 0.5, respectively. 
65 

Table 6-13. Formula for Calculation of Weight-Adjusted Coumaphos LD50 for the BlackBilled Magpie 

Adjusted LD50(black-billed magpie) (mg/kg-bw) = Avian LD50 (mg/kg-bw) ቀ

SW(g)

TW(g)ቁ

ሺx-1ሻ

ൌ 	 2.4 ൬186

178൰

ሺଵ.ଵହିଵሻ

= 2.4 mg/kg-bw 

Where: 

Avian LD50 = most sensitive avian acute oral toxicity endpoint (2.4 mg/kg-bw) 

SW = body weight of the assessed avian species (186 g black-billed magpie) 

TW = body weight of tested avian species (178 g bobwhite quail) 

x = Mineau scaling factor for birds (EFED default 1.15) 

Table 6-14. Avian Acute Dose-Based Risk Quotient (RQ)a for Exposure via Contact 

with/Ingestion of Hair and Skin Debris from Treated Cattle and/or Contaminated Soil and 

Feed In and Around Treatment Areas Using EECs for Treated Cow Hidesb 

Dose-Based EEC 

(mg a.i./ft2 cow hide) 

Adjusted LD50(black-billed magpie) 

(mg/kg-bw) 

Black-Billed 

Magpie (kg) 

Dose-Based RQa

Texas: Dip Vat Application (42% flowable concentrate)

272b 2.4 0.186 609** 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

101b 2.4 0.186 226** 

** exceeds acute listed and non-listed LOCs (=0.5 and 0.1, respectively) 

a RQൌ	 EEC	ሺmg/ft2	cow	hideሻ

adjusted	LD50 ሺmg/kg‐bwሻ	*	black‐billed	magpie	ሺkgሻ	

To calculate an acute dietary-based RQ for primary exposure of birds to coumaphos, the most 

sensitive avian subacute dietary toxicity endpoint (i.e., LC50 = 82.1 mg/kg-bw for bobwhite 

quail; MRID 00112843) was compared to the dietary-based EECs of 370, 853, and 1228 mg/kgdiet to yield avian acute dietary-based RQs of 4.5, 10, and 15, respectively (= [370, 853, or 

1228]/82.1). These dietary-based acute RQs for exposure via contact with/ingestion of hair and 

skin debris from treated cattle and/or contaminated soil/feed in and around treatment areas 

exceed the avian acute listed and non-listed species LOCs of 0.1 and 0.5, respectively. 

 

To calculate an acute dose-based RQ for secondary exposure of birds to coumaphos, the most 

sensitive avian acute oral toxicity endpoint (i.e., LD50 = 2.4 mg/kg-bw for bobwhite quail; MRID 

00112843) was adjusted for the weight of the red-tailed hawk (i.e., 1100 g; USEPA, 1993b), a 

representative avian predator, according to the formula provided in Table 6-15 and compared to 

the dose-based EECs of 1.17 x 10-5, 2.67 x 10-5, or 3.87 x 10-5 mg a.i./g-bw/day. Avian acute 

dose-based RQs for exposure via ingestion of coumaphos-contaminated bird carcasses are 0.012, 

<0.01, and <0.01 (= [1.17 x 10-5, 2.67 x 10-5, or 3.87 x 10-5]/0.0032). These acute dose-based 

RQs do not exceed the avian acute listed and non-listed species LOCs of 0.1 and 0.5, 

respectively. 

 
66 

Table 6-15. Formula for Calculation of Weight-Adjusted Coumaphos LD50 for the RedTailed Hawk 

Adjusted LD50(red-tailed hawk) (mg/kg-bw) = Avian LD50 (mg/kg-bw) ቀ

SW(g)

TW(g)ቁ

ሺx-1ሻ

ൌ 	 2.4 ൬1100

178 ൰

ሺଵ.ଵହିଵሻ

= 3.2 mg/kg-bw = 0.0032 mg/g-bw 

Where: 

Avian LD50 = most sensitive avian acute oral toxicity endpoint (2.4 mg/kg-bw) 

SW = body weight of the assessed avian species (1100 g red-tailed hawk) 

TW = body weight of tested avian species (178 g bobwhite quail) 

x = Mineau scaling factor for birds (EFED default 1.15) 

To calculate an acute dietary-based RQ for secondary exposure of birds to coumaphos, the most 

sensitive avian subacute dietary toxicity endpoint (i.e., LC50 = 82.1 mg/kg-bw for bobwhite 

quail; MRID 00112843) was compared to dietary-based EECs of 39, 89, and 129 mg/kg-diet to 

yield avian acute dietary-based RQs of 0.48, 0.11, and 1.5 (= [39, 89, or 129]/82.1). The latter 

dietary-based acute RQ for exposure via ingestion of coumaphos-contaminated bird carcasses 

exceeds the avian acute listed and non-listed species LOCs of 0.1 and 0.5, respectively; the 

former RQs exceed the listed species LOC of 0.1.

T-REX was used to calculate avian acute RQs for ingestion of food items on land receiving 

manure from CAFOs (Table 6-16). Avian acute RQs range from 0.02 to 4.52. The avian acute 

non-listed and listed species LOCs of 0.5 and/or 0.1, respectively, are exceeded for small and 

medium birds. 

Table 6-16. Avian Risk Quotients (RQs) for Application of CAFO Manure to Land 

Source of Exposure RQs 

Small 

(20 g) 

Medium 

(100 g) 

Large 

(1000 g) 

Texas: Spray Application (42% flowable concentrate) 

CAFO manure applied to land No incorporation into soil 4.52** 0.71** 0.05 

Incorporation into soil within a day 2.71** 0.43* 0.03 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration) 

CAFO manure applied to land No incorporation into soil 2.77** 0.44* 0.03 

Incorporation into soil within a day 1.54** 0.24* 0.02 

* exceeds avian acute listed species LOC (=0.1) 

**exceeds avian acute non-listed species LOC (=0.5) 

KABAM was used to calculate acute dose- and dietary-based RQs for ingestion of contaminated 

fish (Table 6-17) using a Km of 0.936/d for fish that was derived from raw data for the fish BCF 

study. The LOC of 0.1 for listed species of sandpipers and rails is exceeded for wash-off from 

the skin of 100 cows that enter a body. 
67 

Table 6-17. Avian Risk Quotients (RQs) for Birds Consuming Fish Contaminated by 

Coumaphos 

Source of Fish 

Exposure 

PRZM/EXAMS 

Scenario 

Wash-Off 

Fraction 

Wildlife Species Acute RQs 

Dose-Based DietaryBased 

Texas: Spray Application (42% flowable concentrate)

Runoff from 

non-regulated 

small CAFO 

BSSTurf 0.02 

Sandpipers 0.084 0.002 

Cranes 0.004 0.002 

Rails 0.041 0.002 

Herons 0.005 0.002 

Small osprey 0.004 0.001 

White pelican 0.001 0.000 

Wash-off from 

the skin of 100 

cows that enter a 

body of water 

NA 0.02 

Sandpipers 0.268* 0.005 

Cranes 0.013 0.005 

Rails 0.132* 0.006 

Herons 0.018 0.005 

Small osprey 0.014 0.003 

White pelican 0.003 0.001 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration) 

Runoff from 

non-regulated 

small CAFO 

PA Turf 0.027 

Sandpipers 0.097 0.002 

Cranes 0.005 0.002 

Rails 0.048 0.002 

Herons 0.006 0.002 

Small osprey 0.005 0.001 

White pelican 0.001 0.001 

Wash-off from 

the skin of 100 

cows that enter a 

body of water 

NA 0.027 

Sandpipers 0.135** 0.003 

Cranes 0.007 0.002 

Rails 0.066 0.003 

Herons 0.009 0.002 

Small osprey 0.007 0.001 

White pelican 0.001 0.001 

* exceeds avian acute listed species LOC (=0.1) 

Avian chronic RQs were not calculated for any exposure pathways because of the lack of chronic 

toxicity data specific for coumaphos. Risk to birds from chronic exposure is discussed in the 

Risk Description section of this document. 

6.1.2.2 Mammals 

Mammalian RQs were calculated for two exposure pathways resulting from the application of 

coumaphos to livestock: ingestion of coumaphos-contaminated bird carcasses using dose- and 

dietary-based EECs for coumaphos intake via secondary ingestion (i.e., 4.16 x 10-6-1.38 x 10-5 

mg a.i./g-bw/day and 0.039-0.129 mg/g-diet, respectively) and ingestion of food items on land 

receiving manure from CAFOs using EECs in terms of LD50/ft2 from T-REX. 

Acute dietary-based RQs for mammals were not calculated due to the lack of an acute dietarybased toxicity endpoint. 

To calculate an acute dose-based RQ for secondary exposure of mammals to coumaphos, the 

most sensitive mammalian acute oral toxicity endpoint (i.e., LD50 = 17 mg/kg-bw for rat; MRID 

00110597) was adjusted for the weight of the red fox (i.e., 4500 g; USEPA, 1993b), a 
68 

representative mammalian predator, according to the formula provided in Table 6-18 and 

compared to dose-based EECs of 4.16 x 10-6, 9.49 x 10-6, and 1.38 x 10-5 mg a.i./g-bw/day. 

Mammalian acute dose-based RQs for exposure via ingestion of coumaphos-contaminated bird 

carcasses are <0.01 (= [4.16 x 10-6, 9.49 x 10-6, or 1.38 x 10-5]/0.025). These acute dose-based 

RQs do not exceed the mammalian acute listed and non-listed species LOCs of 0.1 and 0.5, 

respectively. 

 

Table 6-18. Formula for Calculation of Weight-Adjusted Coumaphos LD50 and NOAEL 

for the Red Fox 

Adjusted LD50(red fox) (mg/kg-bw) = Mammalian LD50 (mg/kg-bw) ቀ

SW(g)

TW(g)ቁ

ሺ0.25ሻ

ൌ 	 17 ൬4500

350 ൰

ሺ଴.ଶହሻ

= 25 mg/kg-bw = 0.025 mg/g-bw 

Adjusted NOAEL(red fox) (mg/kg-bw) = Mammalian	NOAEL (mg/kg-bw) ቀ

SW(g)

TW(g)ቁ

ሺ0.25ሻ

ൌ 	 1.79 ൬4500

350 ൰

ሺ଴.ଶହሻ

= 2.63 mg/kg-bw = 0.00263 mg/g-bw 

Where: 

Mammalian LD50 or NOAEL = most sensitive mammalian acute oral or chronic toxicity endpoint (17 or 1.79 

mg/kg-bw, respectively) 

SW = body weight of the assessed avian species (4500 g red fox) 

TW = body weight of tested mammalian species (350 g rat) 

To calculate a chronic dose-based RQ for secondary exposure of mammals to coumaphos, the 

most sensitive mammalian chronic toxicity endpoint (i.e., NOAEL = 1.79 mg/kg-bw for rat; 

MRID 43061701) was adjusted for the weight of the red fox (i.e., 4500 g; USEPA, 1993b), a 

representative mammalian predator, according to the formula provided in Table 6-18 and 

compared to dose-based EECs of 4.16 x 10-6, 9.49 x 10-6, and 1.38 x 10-5 mg a.i./g-bw/day. 

Mammalian chronic dose-based RQs for exposure via ingestion of coumaphos-contaminated bird 

carcasses are <0.01 (= [4.16 x 10-6, 9.49 x 10-6, or 1.38 x 10-5]/0.00263). These chronic dosebased RQs do not exceed the mammalian chronic listed and non-listed species LOC of 1. 

To calculate a chronic dietary-based RQ for secondary exposure of mammals to coumaphos, the 

most sensitive mammalian chronic toxicity endpoint (i.e., NOAEC = 25 mg/kg-diet for rat; 

MRID 43061701) was compared to dietary-based EECs of 39, 89, and 129 mg/kg-diet to yield 

mammalian chronic dietary-based RQs of 1.5, 3.5, and 5.2 (= [39, 89, or 129]/25). These 

dietary-based chronic RQs for exposure via ingestion of coumaphos-contaminated bird carcasses 

exceed the mammalian chronic listed and non-listed species LOC of 1. 

T-REX was used to calculate mammalian RQs for ingestion of food items on land receiving 

manure from CAFOs (Table 6-19). Mammalian acute RQs range from <0.01 to 0.28. The 

mammalian acute listed species LOC of 0.1 is exceeded for small and medium mammals. 
69 

Table 6-19. Mammalian Risk Quotients (RQs) for Application of CAFO Manure to Land 

Source of Exposure RQs 

Small 

(15 g) 

Medium 

(35 g) 

Large 

(1000 g) 

Texas: Spray Application (42% flowable concentrate) 

CAFO manure applied to land No incorporation into soil 0.28* 0.15* 0.01 

Incorporation into soil within a day 0.17* 0.09 0.01 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration) 

CAFO manure applied to land No incorporation into soil 0.17* 0.09 0.01 

Incorporation into soil within a day 0.09 0.05 <0.01 

* exceeds mammalian acute listed species LOC (=0.1) 

KABAM was used to calculate dose- and dietary-based RQs for ingestion of contaminated fish 

(Table 6-20) using a Km of 0.936/d for fish that was derived from raw data for the fish BCF 

study. There are no exceedances for mammals ingesting contaminated fish. 

Table 6-20. Mammalian Risk Quotients (RQs) for Mammals Consuming Fish 

Contaminated by Coumaphos 

Source of 

Fish 

Exposure 

PRZM/ 

EXAMS 

Scenario 

Wash-Off 

Fraction 

Wildlife Species Acute DoseBased RQs Chronic RQs 

DoseBased DietaryBased 

Texas: Spray Application (42% flowable concentrate)

Runoff from 

nonregulated 

small CAFO 

BSSTurf 0.38 

Fog/water shrew 0.003 0.041 0.007 

Rice rat/star-nosed mole 0.003 0.038 0.006 

Small mink 0.001 0.017 0.003 

Large mink 0.001 0.019 0.003 

Small river otter 0.002 0.020 0.003 

Large river otter 0.001 0.012 0.001 

Wash-off 

from the skin 

of 100 cows 

that enter a 

body of 

water 

NA 0.38 

Fog/water shrew 0.010 0.132 0.024 

Rice rat/star-nosed mole 0.009 0.122 0.018 

Small mink 0.004 0.055 0.009 

Large mink 0.004 0.061 0.009 

Small river otter 0.005 0.065 0.009 

Large river otter 0.003 0.037 0.005 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Runoff from 

nonregulated 

small CAFO 

PA Turf 0.116 

Fog/water shrew 0.004 0.048 0.009 

Rice rat/star-nosed mole 0.003 0.044 0.007 

Small mink 0.001 0.020 0.003 

Large mink 0.002 0.022 0.003 

Small river otter 0.002 0.024 0.003 

Large river otter 0.001 0.013 0.002 

Wash-off 

from the skin 

of 100 cows 

that enter a 

body of 

water 

NA 0.116 

Fog/water shrew 0.005 0.067 0.012 

Rice rat/star-nosed mole 0.005 0.062 0.009 

Small mink 0.002 0.028 0.004 

Large mink 0.002 0.030 0.004 

Small river otter 0.002 0.033 0.004 

Large river otter 0.001 0.019 0.002 

6.1.2.3 Terrestrial (Upland and Semi-Aquatic) Plants 

RQs for terrestrial (upland and semi-aquatic) plants for exposure via CAFO manure applied to 

land or runoff from land to which CAFO manure has been applied were not calculated because 
70 

of the lack of terrestrial plant toxicity data specific to coumaphos. Risk to plants from these two 

exposure pathways is discussed in the Risk Description section of this document. 

6.1.2.4 Honey Bees (In-Hive Use) 

RQs for honey bees exposed to coumaphos via impregnated strips placed in hives to control 

varroa mites and hive beetles were not calculated due to the lack of exposure and/or toxicity data 

that is suitable for a quantitative approach. Risk to honey bees from exposure to coumaphos is 

discussed in the Risk Description section of this document. 

6.1.3 Probit Slope Dose-Response Analysis of LOC and Acute RQ Values 

As part of risk estimation, the Agency provides additional information on the potential for acute 

direct effects to exposed individuals in terms of the chance of an individual event (i.e., mortality 

or immobilization) should exposure at the EEC actually occur for a species with sensitivity to 

coumaphos on par with the acute toxicity endpoint selected for RQ calculation. This is 

accomplished using the slope of the dose-response relationship available from the toxicity study 

used to establish the acute toxicity measures of effect for each taxonomic group. The individual 

effects probability associated with the acute RQ is based on the mean estimate of the slope and 

an assumption of a probit dose-response relationship. In addition to a single effects probability 

estimate based on the mean, upper and lower estimates of the effects probability are also 

provided to account for variance in the slope, if available. Individual effect probabilities are 

calculated based on an Excel spreadsheet tool IECV1.1 (Individual Effect Chance Model 

Version 1.1) developed by U.S. EPA, OPP, Environmental Fate and Effects Division (June 22, 

2004). The model provides the option of inserting taxa-specific probit slopes and confidence 

intervals. If specific information is not available, the model uses a default value of 4.5 for the 

probit slope and 2 and 9 for the upper and lower 95% confidence interval bounds. 

Chances of effect (e.g., mortality, immobilization) for an individual organism are provided in 

Table 6-21 (fish and aquatic invertebrates) and Table 6-22 (birds and mammals). For wash-off 

from treated livestock that enter bodies of water, this analysis was conducted using the RQ or 

LOC associated with 1 and 100 cows entering a body of water, depending on the taxon. The 

upper limit of 100 cows was selected based on literature indicating that a 6 foot deep, 1 acre farm 

pond would be suitable for watering 100 cows (Bray, 2013). 
71 

Table 6-21. Chance of Effect (i.e., Mortality or Immobilization) for an Individual Fish or 

Aquatic Invertebrate at Selected Acute Risk Quotient (RQ) or Level of Concern (LOC)* 

Values for Coumaphos 

Taxon RQ or LOC* Probit 

Slope

(95% C.I.) 

Chance of Effect 

1 in... 

 (95% C.I.) 

Freshwater 

fish 

LOC: Runoff 0.05 4.5 (2-9) 

(default) 

4.18x108

(216-1.75x1031) LOC: Wash-off for 1 cow entering a body of water 0.05 

LOC: Wash-off for 100 cows entering a body of water 0.05 

Estuarine/ 

marine fish 

LOC: Runoff 0.05 4.5 (2-9) 

(default) 

4.18x108

(216-1.75x1031) LOC: Wash-off for 1 cow entering a body of water 0.05 

LOC: Wash-off for 100 cows entering a body of water 0.05 

Freshwater 

invertebrates 

RQ: Runoff from CAFO manure applied to land in 

Texas 

RQ: Runoff from CAFO manure applied to land in the 

rest of the U.S. 

0.68 

0.54 

4.5 (2-9) 

(default) 

4 (3-15) 

9 (4-125) 

RQ: Runoff from non-regulated small CAFO in Texas 

RQ: Runoff from non-regulated small CAFO in the 

rest of the U.S. 

3.4 

3.9 

1 (1-1) 

1 (1-1) 

RQ: Runoff from rangeland in Texas 

LOC: Runoff from rangeland in the rest of the U.S. 

0.07 

0.05 

9.88x106

(95-7.58x1024) 

4.18x108

(216-1.75x1031) 

RQ: Wash-off for 1 cow entering a body of water in 

Texas 

RQ: Wash-off for 1 cow entering a body of water in 

the rest of the U.S. 

0.11 

0.05 

1.25x105 

(37-3.19x1017) 

4.18x108

(216-1.75x1031) 

RQ: Wash-off for 100 cows entering a body of water 

in Texas 

RQ: Wash-off for 100 cows entering a body of water 

in the rest of the U.S. 

11 

5 

1 (1-1) 

1 (1-1) 

Estuarine/ 

marine 

invertebrates 

LOC: Runoff from CAFO manure applied to land 0.05 

4.5 (2-9) 

(default) 

4.18x108

(216-1.75x1031) 

RQ: Runoff from non-regulated small CAFO in Texas 

RQ: Runoff from non-regulated small CAFO in the 

rest of the U.S. 

0.13 

0.15 

2.99x104

 (27-1.31x1015) 

9.56x103

 

(21-1.65x1013) 

LOC: Wash-off for 1 cow entering a body of water 0.05 4.18x108

(216-1.75x1031) 

LOC: Runoff from rangeland 

. 

0.05 4.18x108

(216-1.75x1031) 

RQ: Wash-off for 100 cows entering a body of water 

in Texas 

RQ: Wash-off for 100 cows entering a body of water 

in the rest of the U.S. 

0.4 

0.2 

28 

(5-5.85x103

) 

1.21x103

(13-6.33x109

) 

* listed species LOC (=0.05) was used for analysis when RQ(s) did not exceed listed species LOC 
72 

Table 6-22. Chance of Effect (i.e., Mortality) for an Individual Bird or Mammal at Selected 

Acute Risk Quotient (RQ) or Level of Concern (LOC)* Values for Coumaphos 

Taxon RQ or LOC* Probit Slope

(95% C.I.) 

Chance of Effect 

1 in... 

 (95% C.I.) 

Bird RQ: Dose-based exposure for primary exposure in Texas 

RQ: Dose-based exposure for primary exposure in the 

rest of the U.S. 

609 

226 

4.3 (1.2-7.3) 

(MRID 

00112843) 

1 (1-1) 

1 (1-1) 

LOC: Dose-based exposure for ingestion of bird 

carcasses (secondary exposure) 

0.1 1.17x105

(9-6.95x1012) 

RQ: Dose-based exposure for application of CAFO 

manure to land in Texas (small bird) 

RQ: Dose-based exposure for application of CAFO 

manure to land in the rest of the U.S. (small bird) 

4.52 

2.77 

1 (1-1) 

1 (1-1) 

RQ: Dietary-based exposure for primary exposure 15 6.6 (3.9-9.7) 

(MRID 

00112843) 

1 (1-1) 

RQ: Dietary-based exposure for ingestion of bird 

carcasses (secondary exposure) 

1.5 1 (1-1) 

Mammal LOC: Dose-based exposure for ingestion of bird 

carcasses (secondary exposure) 

0.1 

4.5 (2-9) 

(default) 

2.94x105

(44-8.86x1018) 

RQ: Dose-based exposure for application of CAFO 

manure to land in Texas (small bird) 

RQ: Dose-based exposure for application of CAFO 

manure to land in the rest of the U.S. (small bird) 

0.28 

0.17 

156 

(8-3.07x106

) 

3.74x103

(17-4.62x1011) 

C.I. = confidence interval 

* listed species LOC (=0.1) was used for analysis when RQ did not exceed listed species LOC 
73 

6.2 Risk Description 

The following risk description explains the overall direct effect conclusions regarding potential 

ecological risk from the various uses of coumaphos. The risk description takes into 

consideration all lines of evidence including: risk estimates (i.e., RQ results); information on the 

chance of individual effect (i.e., mortality or immobilization) for the acute RQ values; 

comparisons of non-definitive toxicity endpoints (i.e., >) to EECs; data from monitoring, field 

studies, and reported incidents that may provide additional insights into the likelihood of 

exposure; and other factors that modify the likelihood of exposure such as timing of application, 

overlap of area affected and the degree of effect with the presence/absence of taxa, species 

sensitivity distribution, and presence/absence of dietary items. 

6.2.1 Direct Effects to Aquatic Organisms 

Risk to aquatic organisms from the following four exposure pathways was estimated: 

 uptake from surface waters receiving runoff from land to which contaminated manure has 

been applied; 

 uptake from surface waters receiving runoff from non-regulated small CAFOs (i.e., <300 

animals); 

 uptake from surface waters receiving runoff from rangeland where treated livestock 

graze; and 

 uptake from surface waters into which treated livestock wade (i.e., wash-off from treated 

livestock that enter bodies of water). 

It should be noted that the possibility of an LOC exceedance for wash-off from treated livestock 

that enter bodies of water depends on the number of cows involved (i.e., the number of cows that 

must of wade into 1 acre, 6 foot deep body of water). A 6 foot deep, 1 acre farm pond is suitable 

for watering 100 cows (Bray, 2013). Therefore, 100 cows was used as a cut-off for determining 

that there may be a concern for risk from wash-off from treated livestock that enter bodies of 

water. 

6.2.1.1 Fish and Aquatic-Phase Amphibians 

For fish, no acute or chronic LOCs (>0.05 and 1, respectively) are exceeded for exposure 

pathways involving runoff. In addition, hundreds of cows would need to enter a 1 acre, 6 foot 

deep body of water for there to be LOC exceedances. Probit slope dose-response analyses 

indicate a small chance of individual mortality (i.e., 1 in 4.18x108

) for exposure via wash-off 

from cow entering a body of water and runoff from CAFO manure applied to land, non-regulated 

small CAFOs, or rangeland. Collectively, these analyses indicate that the potential for risk to 

freshwater and estuarine/marine fish and aquatic-phase amphibians as a result of the registered 

uses of coumaphos on livestock is low. 

6.2.1.2 Aquatic Invertebrates 

Freshwater invertebrates are generally more sensitive to coumaphos than freshwater 

invertebrates, and there are more exceedances for freshwater invertebrates compared to their 

estuarine/marine counterparts. 
74 

For freshwater invertebrates in Texas and the rest of the U.S., acute and chronic LOCs for listed 

and non-listed species (>0.5 and 1, respectively) are exceeded for runoff from unincorporated 

CAFO manure applied to land and runoff from non-regulated small CAFOs. For runoff from 

rangeland, only the acute listed species LOC (0.05) is exceeded for Texas. Furthermore, only 

one to ten cows would have to enter a 1 acre, 6 foot deep body of water for there to be acute and 

chronic LOC exceedances for listed and non-listed species of freshwater invertebrates. Probit 

slope dose-response analyses for the exposure pathways yielding the highest RQs – runoff from 

non-regulated small CAFOS and wash-off from 100 cows entering a body of water – indicate a 

high chance of individual mortality (i.e., 1 in 1) for freshwater invertebrates. 

For estuarine/marine invertebrates, the only exceedances for pathways involving runoff are for 

exposure via runoff from non-regulated small CAFOs for listed species. For wash-off from 

treated cows that enter bodies of water (i.e., 1 acre, 6 foot deep body of water), there are 

exceedances for acute exposure of listed species and chronic exposure of listed and non-listed 

species for 13 to 86 cows. Probit slope dose-response analyses for the exposure pathways 

yielding the highest RQs – runoff from non-regulated small CAFOS and wash-off from 100 

cows entering a body of water – indicate a 1 in 9560 to 29,900 and 1 in 18 to 1210 chance of 

individual mortality, respectively. 

The potential for risk to benthic invertebrates was evaluated via the use of pore water EECs and 

toxicity data for freshwater invertebrates closely parallels that of the potential for risk to 

freshwater invertebrates. However, there is some uncertainty associated with this conclusion 

since the toxicity endpoints used to calculate RQs were generated from studies in which 

exposure occurred via the water column instead of via sediment. 

Collectively, these analyses imply that freshwater, estuarine/marine, and benthic invertebrates 

may be adversely affected by the registered use of coumaphos on livestock. This conclusion is 

not unexpected given the conclusions of previous assessments (see Section 2.2) as well as 

toxicity data indicating that invertebrates are exquisitely sensitive to coumaphos, which targets 

invertebrates. 

6.2.1.3 Aquatic Plants 

For aquatic vascular plants, the listed species LOC (1) is not exceeded for runoff, regardless of 

the source of exposure, suggesting that concern for risk to listed species from exposure via this 

pathway is low. RQs for non-listed aquatic vascular plants were not calculated because the EC50

endpoint is non-definitive (i.e., >166 μg/L). However, the EC50 for aquatic vascular plants must 

be greater than the NOAEC of 166 μg a.i./L. Since there is no LOC exceedance using the 

NOAEC, concern for risk to non-listed aquatic vascular plants from exposure to coumaphos via 

runoff is also presumed low. The estimation of risk to aquatic vascular plants from exposure via 

wash-off from treated livestock that enter bodies of water indicates that over 1000 cows would 

have to wade into 1 acre, 6 foot deep body of water for there to be a concern for risk to aquatic 

vascular plants from exposure via this pathway which is unlikely. Collectively, these analyses 

imply that the concern for risk to aquatic vascular plants from the registered use of coumaphos 

on livestock is low. 
75 

RQs for aquatic non-vascular plants for exposure via runoff and wash-off were not calculated 

because of the lack of toxicity data specific to coumaphos. Instead, the most sensitive aquatic 

non-vascular plant toxicity endpoints for a surrogate organophosphate insecticide were compared 

to peak EECs for runoff and wash-off (Tables 6-23 and 6-24). Aquatic non-vascular plant 

toxicity data are available for the several organophosphate insecticides including chlorpyrifos, 

diazinon, dichlorvos, dicrotophos, dimethoate, EPN, fenthion, naled, oxydemeton-methyl, 

phorate, and trichlorfon. Of the available data, naled is the most toxic to aquatic non-vascular 

plants. The most sensitive endpoints for naled are those for N. pelliculosa: EC50 = 24 μg a.i./L 

and NOAEC = 4.2 μg a.i./L. For runoff, peak EECs do not exceed the toxicity endpoints for any 

of the scenarios. For wash-off from the skin of treated livestock that enter bodies of water, 

hundreds of cows would need to wade into 1 acre, 6 foot deep body of water for the EECs to be 

greater than the endpoints for naled. Collectively, these analyses indicate that the potential for 

risk to aquatic non-vascular plants as a result of the registered uses of coumaphos on livestock is 

low. However, there is uncertainty associated with this risk conclusion given that aquatic nonvascular plants may be more or less sensitive to coumaphos than to naled. 

Table 6-23. Comparison of Aquatic Non-Vascular Toxicity Endpoints for Naled to Runoff 

Estimated Environmental Concentrations (EECs) for Coumaphos + Coumaphoxon 

PRZM/ 

EXAMS 

Scenarios 

Sources of a.i. 

from Application 

Scenario 

Wash-Off 

Fraction 

Peak 

EEC 

(μg/L) 

Naled 

EC50 

(μg/L) 

 Naled 

NOAEC 

(μg/L)

Peak EEC 

> EC50? 

Peak EEC 

> 

NOAEC? 

Texas: Spray Application (42% flowable concentrate)

BSSTurf Runoff from CAFO 

manure applied to land 

(no incorporation) 

0.02 0.05 

24 4.2 No No 

Runoff from CAFO 

manure applied to land 

(incorporation) 

0.02 0.0031 

Runoff from nonregulated small CAFO 0.02 0.25 

RangeBSS Runoff from rangeland 0.02 0.005 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

PA Turf Runoff from CAFO 

manure applied to land 

(no incorporation) 

0.027 0.04 

24 4.2 No No 

Runoff from CAFO 

manure applied to land 

(incorporation) 

0.027 0.0022 

Runoff from nonregulated small CAFO 0.027 0.29 

Runoff from rangeland 0.027 0.0013 

 
76 

Table 6-24. Comparison of Aquatic Non-Vascular Toxicity Endpoints for Naled to 

Estimated Environmental Concentrations (EECs) for Coumaphos + Coumaphoxon for 

Wash-Off from the Skin of Treated Livestock That Enter Bodies of Water 

Maximum Application Rate Wash-Off 

Fraction

Peak EEC

(EEC/cow) 

(μg/L) 

Naled 

EC50 

(μg/L) 

 Naled 

NOAEC 

(μg/L) 

Number of Cows 

Needed to Exceed 

Toxicity Endpointb

Type (lb a.i./ 

animal) 

(mg a.i./ 

ft2 cow hide) 

Non-listed Listed 

Texas: Spray Application (42% flowable concentrate)

Single 0.027 274 0.02 0.008 24 4.2 3000 525 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Single 0.01 101 0.02 0.004 24 4.2 6000 1050 a

 1 acre, 6 foot deep body of water 

b

 Toxicity endpoint/peak EEC 

6.2.2 Direct Effects to Terrestrial Organisms 

6.2.2.1 Birds, Reptiles, and Terrestrial-Phase Amphibians 

Risk to birds from the following four exposure pathways was estimated: 

 contact with/ingestion of hair and skin debris from treated cattle and/or contaminated soil 

and feed in and around treatment areas (primary exposure); 

 ingestion of contaminated bird carcasses (secondary exposure); 

 ingestion of food items on land receiving manure from CAFOs; and 

 ingestion of contaminated fish. 

For primary exposure, avian acute dose- and dietary-based RQs of 226 to 609 and 4.5 to 15, 

respectively, exceed avian acute listed and non-listed species LOCs (0.1 and 0.5, respectively). 

These RQs for avian primary exposure correspond to a 1 in 1 chance of individual mortality. For 

secondary exposure via the consumption of contaminated bird carcasses, none of the avian acute 

dose-based RQs exceed acute LOCs. However, the avian acute dietary-based RQs of 0.48 to 1.5 

exceed avian acute non-listed and/or listed species LOCs. The highest RQ for avian secondary 

exposure corresponds to a high chance of individual mortality (i.e., 1 in 1). For ingestion of food 

items on land receiving manure from CAFOs, RQs for small and medium birds exceed the avian 

acute non-listed and/or listed species LOCs, and the highest RQs (i.e., those for small mammals) 

correspond to a 1 in 1 chance of individual mortality. For ingestion of contaminated fish, acute 

RQs exceed the listed species LOC for only sandpipers and rails. 

Avian chronic RQs were not calculated due to the lack of chronic toxicity data for coumaphos. 

Instead, the most sensitive avian chronic toxicity endpoint for a surrogate organophosphate 

insecticide was compared directly to EECs for the three of the four exposure pathways (Table 6-

25). Comparisons were not made for exposure via CAFO manure applied to land because only 

acute EECs (in terms of LD50/ft2

) can be modeled for broadcast application of granules in TREX. Avian chronic, reproductive toxicity data are available for the following 

phosphorothioates: fenitrothion, parathion, and methyl parathion. Of the available data, 

parathion is the most toxic to birds on a chronic basis. The most sensitive endpoint for parathion 

is that for mallard duck: NOAEC = 2.85 mg/kg-diet. EECs are greater than parathion’s chronic 

toxicity endpoint for exposure via hair and skin debris from treated cattle and/or contaminated 

soil and feed in and around treatment areas indicating that birds may be at risk from chronic 
77 

exposure via this pathway. In contrast, dietary-based EECs for secondary exposure via ingestion 

of contaminated bird carcasses and fish contaminated via runoff or wash-off are less than the 

estimated chronic toxicity endpoint suggesting the concern for risk to birds via these pathways is 

low. However, there is uncertainty associated with these risk conclusions for chronic exposure 

given that birds may be more or less sensitive to coumaphos than to parathion on a chronic basis. 

It should be noted that previous assessments including the 1996 RED did not assess risk to birds 

from chronic exposure with the rationale being that significant acute exposure of birds to 

coumaphos would likely result in mortality before chronic effects could occur (USEPA, 1996). 

Table 6-25. Comparison of an Avian Chronic Toxicity Endpoint for Parathion to Estimated 

Environmental Concentrations (EECs) for Coumaphos 

Source of Exposure Wildlife Species EEC 

(mg/kg-diet) 

Parathion 

Chronic Toxicity 

Endpoint 

(mg/kg-diet) 

EEC > 

Toxicity 

Endpoint? 

Hair and skin debris from treated 

cattle and/or contaminated soil and 

feed in and around treatment areas 

NA 

1228 

853 2.85 Yes 

370 

Contaminated bird carcasses 

(secondary exposure) NA 

0.039 

0.089 2.85 No 

0.129 

Texas: Fish contaminated via runoff Sandpipers 0.14 

2.85 No 

Cranes 0.13 

Rails 0.15 

Herons 0.13 

Small osprey 0.07 

White pelican 0.04 

Texas: Fish contaminated via washoff Sandpipers 0.45 

2.85 No 

Cranes 0.40 

Rails 0.48 

Herons 0.41 

Small osprey 0.22 

White pelican 0.12 

Rest of the U.S.: Fish contaminated 

via runoff 

Sandpipers 0.16 

2.85 No 

Cranes 0.14 

Rails 0.17 

Herons 0.15 

Small osprey 0.08 

White pelican 0.04 

Rest of the U.S.: Fish contaminated 

via wash-off 

Sandpipers 0.23 

2.85 No 

Cranes 0.20 

Rails 0.24 

Herons 0.20 

Small osprey 0.11 

White pelican 0.06 

NA = not applicable 

Collectively, these analyses imply that birds may be at risk from acute exposure via multiple 

pathways as a result of the registered use of coumaphos on livestock. This concern for risk to 

birds is supported by documented incidents involving birds and coumaphos (see Section 5.3) and 

the conclusion of previous assessments (see Section 2.2). 
78 

It should be noted that the conclusions for risk from primary exposure via contact with/ingestion 

of hair and skin debris from treated cattle and/or contaminated soil and feed in and around 

treatment areas and secondary exposure via ingestion of contaminated bird carcasses are based 

on EECs calculated using several conservative assumptions (see Section 4.3.1.2) and mean 

residues of coumaphos detected in bovine hair (a surrogate for potential contaminated food 

items) 1, 24, and 72 hours post-treatment as reported in the pilot field study (MRID 42512604). 

In addition, there are several uncertainties associated with risk estimates from exposure via 

ingestion of contaminated fish including the following: 

 EECs for this pathway were determined using surface water and pore water EECs which 

were calculated using conservative assumptions described in Section 4.2. 

 In the absence of data, the metabolic rate constant for lower trophic levels was assumed 

to be zero. Metabolism of coumaphos by lower trophic levels would result in lower 

EECs and thus decreased estimates of risk (i.e., lower RQs). 

6.2.2.2 Mammals 

Risk to mammals from the following three exposure pathways was estimated: 

 ingestion of contaminated bird carcasses (secondary exposure); 

 ingestion of food items on land receiving manure from CAFOs; and 

 ingestion of contaminated fish. 

For secondary exposure via ingestion of contaminated bird carcasses, mammalian acute dosebased RQs (<0.01) do not exceed mammalian acute listed and non-listed species LOCs (0.1 and 

0.5, respectively), and a probit dose-response analysis using the listed species LOC of 0.1 

indicates a relatively low chance of individual mortality (i.e., 1 in 2.94x105). In addition, 

mammalian chronic dose-based RQs (<0.01) for secondary exposure do not exceed the 

mammalian chronic LOC of 1. However, mammalian chronic dietary-based RQs (1.5-3.2) for 

secondary exposure do exceed the mammalian chronic LOC. For exposure via ingestion of food 

items on land receiving manure from CAFOs, acute RQs exceed the mammalian acute LOC (0.1) 

for listed species, and the highest RQs (i.e., those for small mammals) correspond to a 1 in 156 to 

1 in 3.74x104

 chance of individual mortality. For exposure via ingestion of contaminated fish, 

there are no exceedances of LOCs. Collectively, these analyses imply that mammals may be at 

risk from chronic exposure via ingestion of contaminated bird carcasses (secondary exposure) 

and acute exposure via ingestion of food items on land receiving manure from CAFOs as a result 

of the registered use of coumaphos on livestock. It should be noted that this conclusion contrasts 

with that of previous assessments because those assessments did not assess risk to mammals via 

contaminated bird carcasses or application of CAFO manure to land. 

Furthermore, it should be noted that the conclusions for risk from secondary exposure via 

ingestion of contaminated bird carcasses were based on EECs calculated using several 

conservative assumptions (see Section 4.3.1.2) and mean residues of coumaphos detected in 

bovine hair (a surrogate for potential contaminated food items) 1, 24, and 72 hours posttreatment as reported in the pilot field study (MRID 42512604). 
79 

6.2.2.3 Terrestrial (Upland and Semi-Aquatic) Plants 

RQs for terrestrial (upland and semi-aquatic) plants for exposure via CAFO manure applied to 

land or runoff from land to which CAFO manure has been applied were not calculated because 

of the lack of terrestrial plant toxicity data specific to coumaphos. Instead, the most sensitive 

terrestrial plant endpoints for a surrogate organophosphate insecticide were compared to direct 

application and runoff EECs for CAFO manure (Table 6-26). Terrestrial plant toxicity data are 

available for the several organophosphate insecticides including diazinon, disulfoton, fosthiazate, 

isofenfos, and profenofos. Of the available data, profenofos is the most toxic to terrestrial plants. 

None of the EECs are greater than the toxicity endpoints for profenofos. This analysis indicates 

that the potential for risk to terrestrial (upland and semi-aquatic) plants as a result of the 

registered uses of coumaphos on livestock is low. However, there is uncertainty associated with 

this risk conclusion given that terrestrial plants may be more or less sensitive to coumaphos. 
80 

Table 6-26. Comparison of Terrestrial Plant Toxicity Endpoints for Profenofos to Estimated Environment(EECs) for Coumaphos 

Source of Exposure Direct 

Application

EEC 

(lb a.i./A) 

Runoff EEC 

(lb a.i./A) 

Seedling Emergence 

(lb a.i./A) 

Vegetative V

 (lb a.i./A

All Areas Dry 

(Upland) 

Areas 

SemiAquatic 

Areas 

Monocot Dicot Monocot 

EC25 NOAEC EC25 NOAEC EC25 NOAEC EC

Texas: Spray Application (42% flowable concentrate)CAFO manure applied to land

No incorporation into soil 0.015 

0.0003 0.003 

>1 1 0.13 0.111 NA 1 N

Incorporation into soil within a day 

0.00018 0.0018 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)CAFO manure applied to land

No incorporation into soil 0.0092 

0.000184 0.00184 

>1 1 0.13 0.111 NA 1 N

Incorporation into soil within a day 

0.000102 0.00102 

NA = not applicable 
81 

6.2.2.4 Honey Bees (In-Hive Use) 

RQs for honey bees exposed to coumaphos via impregnated strips placed in hives to control 

varroa mites and hive beetles were not calculated due to the lack of exposure and/or toxicity data 

that is suitable for a quantitative approach. Instead, EECs in the form of open literature data on 

coumaphos residues (mg/kg) detected in bees and queen cells from hives treated with 

coumaphos-impregnated strips during controlled experiments (E066848) were compared to open 

literature data on the toxicity of coumaphos to bees (Table 6-27). The NOAEC for exposure via 

queen cups (10 mg/kg) exceeds the lowest queen cell EEC (8.11 mg/kg), and the LOAEC for 

exposure via queen cups (100 mg/kg) is within the range of queen cell EECs (8.11-237 mg/kg). 

In addition, the lowest LD50’s (23.4, 24.2 mg/kg) are almost equal to the highest concentration of 

coumaphos detected in bees (23.26 mg/kg). This qualitative assessment indicates that there may 

be a concern for risk to honey bees from the registered in-hive use of coumaphos. It should be 

noted that the range of coumaphos EECs reported as part of a broad survey of pesticide residues 

in commercial bee hives in North America (MRID 49497801) generally confirm concentrations 

measured during the controlled experiment in which hives were treated with coumaphosimpregnated strips. 

Table 6-27. Comparison of A) Estimated Environmental Concentrations (EECs) of 

Coumaphos and B) Coumaphos Toxicity Data for Honey Bees 

A) EECs 

Sample Type Conc. (mg/kg) Source & Classification 

Queen cells 8.11-237a E066848 Qualitative 

Wax 12.69-120a

0.001-91.9b

E066848 Qualitative 

MRID 49497801 

Bees 0.83-23.26a

0.001-0.762b

E066848 Qualitative 

MRID 49497801 

Pollen 0.001-5.828b MRID 49497801 

B) Toxicity Data 

Route of Exposure Endpoint (mg/kg) Source & Classification 

Queen cups 10-day NOAEC = 10 

10-day LOAEC = 100 

E100910 Quantitative 

E100380 Quantitative 

Contact 24-hr LD50 = 159.3c E119503 Qualitative 

Oral 

8 day old bees: 48-hr LD50 = 23.4c

 

14 day old bees: 48-hr LD50 = 24.2c

 

3 day old bees: 48-hr LD50 = 47.19c

E101175 Quantitative 

a

 from hives treated with coumaphos-impregnated strips 

b

 whether or not the samples were from hives that were treated with coumaphos is not known 

a

 (LD50 (μg/bee) / 128 μg/bee)*1000 

6.3 Summary of Direct Effects 

A summary of the direct effects of coumaphos to aquatic and terrestrial organisms is provided in 

Tables 6-28 and 6-29. 
82 

Table 6-28. Summary of Direct Effects for Aquatic Organisms 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Inciden

Exposure pathways: 

Runoff from land 

to which CAFO 

manure has been 

applied 

Runoff from nonregulated small 

CAFOs (i.e., < 300 

animals) 

Runoff from 

rangeland 

Wash-off from 

treated livestock 

that enter bodies 

of water

Freshwater fish and aquatic-phase amphibians 

Listed No No No No No Non- No Listed No No No No No 

Estuarine/marine fish 

Listed No No No No No Non- No Listed No No No No No 

Freshwater invertebrates 

Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas: Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

Rest of U.S.: No 

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

No 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Estuarine/marine invertebrates 

Listed Yes No 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

No 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

NonListed Yes No No No 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

Benthic (sedimentdwelling) invertebrates 

Listed Yes 

RQs not calculated 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) RQs not calculated 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) No 

Non- Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Texas, 

Rest of U.S.: 

Yes 

(acute & chronic) 

Aquatic vascular plants 

Listed No No No No No Non- No Listed No No No No No 
83 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Inciden

Exposure pathways: 

Runoff from land 

to which CAFO 

manure has been 

applied 

Runoff from nonregulated small 

CAFOs (i.e., < 300 

animals) 

Runoff from 

rangeland 

Wash-off from 

treated livestock 

that enter bodies 

of water

Aquatic non-vascular plants 

Listed NA 

RQs not calculated No 

NonListed No 

NA = not applicable; no listed aquatic non-vascular plants * Direct or indirect effects to specific listed species have not been definitively determined; further investigation into temporal, geographical, and the registered uses and affected taxa is needed before definitive effects determinations can be made. 
84 

Table 6-29. Summary of Direct Effects for Terrestrial Organisms 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Incidents? C

Exposure pathways: 

Hair and skin 

debris from 

treated cattle 

and/or 

contaminated soil 

and feed in and 

around treatment 

areas 

Contaminated 

bird carcasses 

CAFO 

manure 

applied to 

land 

Runoff from 

land to which 

CAFO manure 

has been applied 

Contaminated 

fish 

Birds, reptiles, and terrestrial-phase amphibians 

Listed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute) 

NA 

Texas, 

Rest of U.S.: 

Yes 

(acute; select 

species) 

Yes 

Recccsibe

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of U.S.: 

Yes 

(acute) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute)

No 

Mammals 

Listed Yes 

NA 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

Texas, 

Rest of 

U.S.: 

Yes 

(acute) NA 

No 

No -

NonListed Yes 

Texas, 

Rest of U.S.: 

Yes 

(chronic) 

No No 

Terrestrial (upland and Listed No RQs not calculated No 

Tto
85 

Taxon Status Concern 

for risk 

from 

direct 

effects?* 

Basis for Conclusion

RQ exceedance (type: acute and/or chronic)? Incidents? C

Exposure pathways: 

Hair and skin 

debris from 

treated cattle 

and/or 

contaminated soil 

and feed in and 

around treatment 

areas 

Contaminated 

bird carcasses 

CAFO 

manure 

applied to 

land 

Runoff from 

land to which 

CAFO manure 

has been applied 

Contaminated 

fish 

semi-aquatic) plants 

NonListed No t

o

Honey bees (in-hive use) 

Listed NA** 

NA Yes T

q

Non- Listed Yes 

NA = not applicable * * Direct or indirect effects to specific listed species have not been definitively determined; further investigation into temporal, geographical, an

the registered uses and affected taxa is needed before definitive effects determinations can be made. ** Not applicable because the analysis for in-hive use only applies to honey bees which are non-listed.
86 

6.4 Listed Species Effects Determinations 

Based on this screening-level assessment, there are potential risks of direct effects to listed 

aquatic invertebrates, birds, and mammals from the use of coumpahos on some of its registered 

use sites. Listed species of all taxa may also be affected through indirect effects because of the 

potential direct effects on listed and non-listed species. Potential direct effects on listed fish, 

aquatic invertebrates, birds, and mammals from the use coumaphos may be associated with 

modification of Primary Constituent Elements (PCEs) of designated critical habitats, where such 

designations have been made. However, at this current stage of the Registration Review process, 

it is premature to make effects determinations for listed species until further scientific analysis 

and refinements are conducted, based on recommendations received from the National Academy 

of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at

http://www.nap.edu/catalog.php?record_id=18344. The NAS report outlines recommendations 

on specific scientific and technical issues related to the development of pesticide risk 

assessments that are compliant with the Endangered Species Act (ESA) and the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

The EPA along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries 

Service (NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA), 

released a summary of their implementation plan for assessing risks of pesticides to listed species 

ahead of the stakeholder workshop held on November 15, 2013. This plan was developed in 

response to the NAS’ recommendations, including a common approach to risk assessment as a 

way of addressing scientific differences between EPA and the Services. During the workshop, 

the agencies received feedback from the public on the interim scientific approaches that were 

developed as part of the initial implementation of the NAS recommendations. These approaches 

will be jointly implemented and vetted as part of a phased iterative process. Once fully vetted, 

EPA will further refine the listed species effects determination portion of this risk assessment. 

To make effects determinations for individual listed species, useful refinements may include, but 

are not limited to, analyses of: 1) more detailed, species-specific ecological and biological data; 

2) more detailed and accurate information on coumaphos use patterns; and 3) sub-county level 

spatial proximity data for the co-occurrence of potential effects areas and listed species and any 

designated critical habitat. Examples of such refinements are described below. 

EFED is currently developing tools that are expected to further refine the assessment and are 

designed to support effects determinations for individual federally listed species and their 

designated critical habitats (where applicable). Scientific information obtained from the 

Services, and other reliable sources is being collated by EFED to address all currently listed 

species. This information is being stored in an Office of Pesticide Programs (OPP) Pesticide 

Registration Information SysteM (PRISM) listed species knowledgebase. The listed species 

knowledgebase consists of an information repository that houses biological and behavioral 

information relevant to individual species (e.g., habitat, diet, and life history, including specific 

temporal and spatial associations) and a document repository that contains supporting documents 

(e.g., USFWS recovery plans) and electronic information (e.g., GIS data files). For terrestrial 

taxa, biological information relevant to the assessment (e.g., diet and body weight) will be used 
87 

to parameterize exposure estimates using a method consistent with currently used methods in the 

T-REX and T-HERPS models. 

Refinements will also include more detailed analyses of the registered uses and specific use 

patterns that result in either “Likely to Adversely Affect” (LAA) or “Not Likely to Adversely 

Affect” (NLAA) determinations for federally listed species. The analyses may include more 

information on where, when, and how coumaphos is used on all use sites. Actual usage data 

(when available) and national land-cover datasets that indicate potential use sites [e.g., National 

Land Cover Dataset (NLCD), Cropland Data Layer (CDL)] may be used to support a more 

refined analysis of where coumaphos is reasonably expected to be used. Similarly, refinements 

on the timing of applications and a more in-depth exploration of agronomic practices for 

coumaphos may be included as part of the refinement. 

The refinements based on individual species data; additional, detailed usage information, when 

available; and recommendations from the NRC report are expected to help to more accurately 

identify potential areas of effect and to better inform effects and habitat determinations for listed 

species and any designated critical habitats. 

7 Uncertainties 

A description of basic assumptions, uncertainties, strengths, and limitations of a typical risk 

assessment is described in Chapter 6 of the Agency’s Overview Document (USEPA, 2004) and 

includes those related to exposure for all taxa, those related to exposure for aquatic species, those 

related to exposure for terrestrial animals, those related to the effects assessment, and those 

associated with the acute LOC values. Additional uncertainties for this assessment are discussed 

below. 

7.1 Estimates of Exposure 

In this risk assessment, EFED attempted to locate the best available data/models for estimating 

coumaphos residues in food items of non-target organisms, CAFO manure that applied to land, 

and potential runoff from CAFOs and rangeland. 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 highest estimate of risk in order to ensure protection of 

ecological receptors and their habitats. However, EFED used wash-off fractions for the 24-hour 

drying time in this assessment because they represent a reasonable time frame after application 

for a treated cow to be caught in a rainstorm or enter a body of water. Potential exposure could 

be higher or lower depending on CAFO operations such as an indoor or outdoor facility, 

numbers of cattle treated/day, and many other variables associated with manure managements 

for crop productions as well as weather conditions. Uncertainty associated with each of these 

individual components could potentially dictate higher or lower EECs. 

7.2 Endocrine Disruptor Screening Program (EDSP) 

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide active 
88 

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by 

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may 

designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, and or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors. 

Coumaphos was not among the group of 58 pesticide active ingredients that received EDSP test 

orders. Additional information on the EDSP, including the policies and procedures, the list of 67 

chemicals, the test guidelines and the Tier 1 screening battery, can be found at 

http://www.epa.gov/scipoly/oscpendo/index.htm. 

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9 Bibliography of Cited MRIDs 

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45752810 Ellis, M. (1998) Evaluation of the Efficacy of Coumaphos Impregnated Strips for 

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94 

45752812 Spivak, M. (1998) Evaluation of the Efficacy of Coumaphos Impregnated Strips 

for the Control of Mites (Varroa jacobsoni) in Bee Colonies in Minnesota: Lab 

Project Number: 74968: 1160: 150.525. Unpublished study prepared by 

University of Minnesota. 15 p. {OPPTS 810.3200} 

45752813 Baxter, J. (1999) Control of the Small Hive Beetle (Aethina tumida): 

(Coumaphos): Lab Project Number: 74589: 75489: 1160. Unpublished study 

prepared by USDA/ARS. 7 p. 

48322801 Banman, C.; Howerton, J.; Lam, C. (2010) Toxicity of Coumaphos Technical to 

Duckweed (Lemna gibba G3) Under Static-Renewal Conditions. Project Number: 

EBAAY011, 9020, 152/413. Unpublished study prepared by Bayer CropScience. 

74 p. 

48322802 Banman, C.; Lam, C. (2010) Toxicity of Coumaphos to the Green Alga 

Pseudokirchneriella subcapitata. Project Number: EBAAY010, 9020, 152/412. 

Unpublished study prepared by Bayer CropScience. 72 p. 
95 

Appendix A: Example PRZM/EXAMS Output 

Water Column 

stored as TX R_02_E.out 

Chemical: Coumaphos 

PRZM environment: TurfBSS.txt, modified Wedday, 31 July 2013 at 14:00:27 

EXAMS environment: pond298.exv, modified Tueday, 26 August 2008 at 06:14:08 

Metfile: w13958.dvf, modified Tueday, 26 August 2008 at 06:14:44 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.06 0.05 0.03 0.02 0.02 0.01 

1962 0.11 0.09 0.06 0.04 0.04 0.02 

1963 0.07 0.07 0.05 0.04 0.04 0.03 

1964 0.21 0.18 0.11 0.08 0.07 0.05 

1965 0.18 0.16 0.12 0.11 0.10 0.09 

1966 0.14 0.13 0.11 0.10 0.10 0.09 

1967 0.13 0.12 0.11 0.10 0.10 0.09 

1968 0.13 0.12 0.11 0.10 0.10 0.10 

1969 0.13 0.12 0.11 0.10 0.10 0.10 

1970 0.19 0.17 0.14 0.12 0.11 0.10 

1971 0.11 0.11 0.10 0.10 0.10 0.10 

1972 0.15 0.13 0.11 0.10 0.10 0.09 

1973 0.24 0.22 0.18 0.15 0.13 0.10 

1974 0.23 0.20 0.16 0.13 0.13 0.12 

1975 0.24 0.22 0.18 0.15 0.15 0.14 

1976 0.21 0.20 0.17 0.15 0.15 0.14 

1977 0.16 0.15 0.14 0.14 0.13 0.13 

1978 0.19 0.18 0.15 0.13 0.13 0.12 

1979 0.33 0.29 0.22 0.18 0.18 0.15 

1980 0.19 0.19 0.17 0.16 0.16 0.15 

1981 0.45 0.40 0.30 0.24 0.22 0.18 

1982 0.25 0.24 0.21 0.20 0.20 0.19 

1983 0.19 0.18 0.18 0.18 0.18 0.17 

1984 0.17 0.16 0.16 0.16 0.16 0.15 

1985 0.19 0.18 0.16 0.15 0.15 0.15 

1986 0.23 0.22 0.18 0.16 0.16 0.14 

1987 0.24 0.22 0.20 0.17 0.17 0.15 

1988 0.16 0.16 0.15 0.15 0.15 0.14 

1989 0.15 0.15 0.14 0.13 0.13 0.13 

1990 0.17 0.16 0.14 0.13 0.13 0.12 

 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.03 0.45 0.40 0.30 0.24 0.22 0.19 
96 

0.06 0.33 0.29 0.22 0.20 0.20 0.18 

0.10 0.25 0.24 0.21 0.18 0.18 0.17 

0.13 0.24 0.22 0.20 0.18 0.18 0.15 

0.16 0.24 0.22 0.18 0.17 0.17 0.15 

0.19 0.24 0.22 0.18 0.16 0.16 0.15 

0.23 0.23 0.22 0.18 0.16 0.16 0.15 

0.26 0.23 0.20 0.18 0.16 0.16 0.15 

0.29 0.21 0.20 0.17 0.15 0.15 0.14 

0.32 0.21 0.19 0.17 0.15 0.15 0.14 

0.35 0.19 0.18 0.16 0.15 0.15 0.14 

0.39 0.19 0.18 0.16 0.15 0.15 0.14 

0.42 0.19 0.18 0.16 0.15 0.13 0.13 

0.45 0.19 0.18 0.15 0.14 0.13 0.13 

0.48 0.19 0.17 0.15 0.13 0.13 0.12 

0.52 0.18 0.16 0.14 0.13 0.13 0.12 

0.55 0.17 0.16 0.14 0.13 0.13 0.12 

0.58 0.17 0.16 0.14 0.13 0.13 0.10 

0.61 0.16 0.16 0.14 0.12 0.11 0.10 

0.65 0.16 0.15 0.12 0.11 0.10 0.10 

0.68 0.15 0.15 0.11 0.10 0.10 0.10 

0.71 0.15 0.13 0.11 0.10 0.10 0.10 

0.74 0.14 0.13 0.11 0.10 0.10 0.09 

0.77 0.13 0.12 0.11 0.10 0.10 0.09 

0.81 0.13 0.12 0.11 0.10 0.10 0.09 

0.84 0.13 0.12 0.11 0.10 0.10 0.09 

0.87 0.11 0.11 0.10 0.08 0.07 0.05 

0.90 0.11 0.09 0.06 0.04 0.04 0.03 

0.94 0.07 0.07 0.05 0.04 0.04 0.02 

0.97 0.06 0.05 0.03 0.02 0.02 0.01 

 

0.10 0.25 0.24 0.21 0.18 0.18 0.17 

 Average of yearly averages: 0.11 

 

Inputs generated by pe5.pl - Novemeber 2006 

Data used for this run: 

Output File: TX R_02_E 

Metfile: w13958.dvf 

PRZM scenario: TurfBSS.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Coumaphos 

Descripti

on 

Variable 

Name 

Value Units Comments 

Molecula

r weight 

mwt 362.5 g/mol 
97 

Henry's 

Law 

Const. 

henry 2.62E-09 atm-m^3/mol 

Vapor 

Pressure 

vapr 1.00E-07 torr 

Solubility sol 20 mg/L 

Kd Kd mg/L 

Koc Koc 5904 mg/L 

Photolysi

s half-life 

kdp 1.38 days Half-life 

Aerobic 

Aquatic 

Metabolis

m 

kbacw 0 days Halfife 

Anaerobi

c Aquatic 

Metabolis

m 

kbacs 0 days Halfife 

Aerobic 

Soil 

Metabolis

m 

asm 0 days Halfife 

Hydrolysi

s: 

pH 7 0 days Half-life 

Method: CAM 1 integer See PRZM manual 

Incorpora

tion 

Depth: 

DEPI cm 

Applicati

on Rate: 

TAPP 0.009 kg/ha 

Applicati

on 

Efficienc

y: 

APPEFF 1 fraction 

Spray 

Drift 

DRFT 0 fraction of application rate applied to pond 

Applicati

on Date 

Date 15-01 dd/mm or dd/mmm or dd-mm or dd-mmm 

Interval 1 interval 10 days Set to 0 or delete line for single app. 

app. rate 

1 

apprate kg/ha 

Interval 2 interval 10 days Set to 0 or delete line for single app. 

app. rate 

2 

apprate kg/ha 

Interval 3 interval 90 days Set to 0 or delete line for single app. 

app. rate 

3 

apprate kg/ha 

Interval 4 interval 10 days Set to 0 or delete line for single app. 

app. rate 

4 

apprate kg/ha 

Interval 5 interval 10 days Set to 0 or delete line for single app. 

app. rate 

5 

apprate kg/ha 
98 

Interval 6 interval 90 days Set to 0 or delete line for single app. 

app. rate 

6 

apprate kg/ha 

Interval 7 interval 10 days Set to 0 or delete line for single app. 

app. rate 

7 

apprate kg/ha 

Interval 8 interval 10 days Set to 0 or delete line for single app. 

app. rate 

8 

apprate kg/ha 

Interval 9 interval 90 days Set to 0 or delete line for single app. 

app. rate 

9 

apprate kg/ha 

Interval 

10 

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

app. rate 

10 

apprate kg/ha 

Interval 

11 

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

app. rate 

11 

apprate kg/ha 

Record 

17: 

FILTRA 

 IPSCND 1 

 UPTKF 

Record 

18: 

PLVKRT 

 PLDKRT 

 FEXTRC 0.5 

Flag for 

Index 

Res. Run 

IR EPA 

Pond 

 

Flag for 

runoff 

calc. 

RUNOFF none none, monthly or total(average of entire run) 
99 

Appendix B: KABAM Analyses 

Table B-1. Input Parameters for KABAM Modeling 

Sources of a.i. 

from 

Application 

Scenario 

PRZM/ 

EXAMS 

Scenario 

WashOff 

Fraction 

Input Parameters 

Water Column

21-day EEC(parent)

 (μg/L) 

 (Coumaphos)

Pore Water 

21-day 

EEC(parent)

 (μg/L) 

 (Coumaphos)

Other Parameters 

Texas: Spray Application (42% flowable concentrate) Log Kow = 4.3 

Koc = 5904 L/kg OC 

Km(fish) = 0.936* 

Avian LD50 = 2.4 mg/kg-bw 

Avian LC50 = 82.1 mg/kg-diet 

(bobwhite quail; MRID 

00112843) 

Avian NOAEC: No data 

Mammalian LD50 = 17 mg/kgbw 

(rat; MRID 00110597) 

Mammalian NOAEC = 25 

mg/kg-diet 

(rat; MRID 43061701)

Runoff from 

non-regulated 

small CAFO 

BSSTurf 0.02 0.25 0.17 

Wash-off from 

the skin of 100 

cows that enter 

a body of 

water 

NA 0.02 0.8 0.5 

Rest of U.S.: Back Rubber Application (11.6% emulsifiable concentration)

Runoff from 

non-regulated 

small CAFO 

PA Turf 0.116 0.29 0.19 

Wash-off from 

the skin of 100 

cows that enter 

a body of 

water 

NA 0.116 0.4 0.3 

* Raw data from the BCF study was used to calculate a fish Km of 0.936/day 
100 

Appendix C: ECOTOX Literature Search – Papers That Were Accepted 

April 2012 refresh 

 1. Barnard, D. R.; Jones, B. G.; Rogers, G. D., and Mount, G. A. Acaricide Susceptibility in the Lone Star Tick: 

Assay Techniques and Baseline Data. J. Econ. Entomol.; 1981; 74, (4): 466-469. 

Notes: EcoReference No.: 113406 

Chemical of Concern: AMZ,CBL,CMPH,CPY,DZ,HCCH,MLN,MXC,PMR,PPCP,PSM,TVP,TXP 

 2. Bevk, D.; Kralj, J., and Cokl, A. Coumaphos Affects Food Transfer Between Workers of Honeybee Apis 

mellifera. Apidologie; 2012; 43, (4): 465-470. 

Notes: EcoReference No.: 157842 

Chemical of Concern: CMPH 

 3. Currie, R. W. and Gatien, P. Timing Acaricide Treatments to Prevent Varroa destructor (Acari: Varroidae) 

from Causing Economic Damage to Honey Bee Colonies. Can. Entomol.; 2006; 138, (2): 238-252. 

Notes: EcoReference No.: 157767 

Chemical of Concern: CMPH,FMA,TAUF 

 4. Damiani, N.; Gende, L. B.; Bailac, P.; Marcangeli, J. A., and Eguaras, M. J. Acaricidal and Insecticidal 

Activity of Essential Oils on Varroa destructor (Acari: Varroidae) and Apis mellifera 

(Hymenoptera: Apidae). Parasitol. Res.; 2009; 106, (1): 145-152. 

Notes: EcoReference No.: 155629 

Chemical of Concern: CMPH,LAVDN,THYME,VFOIL 

 5. DeVaney, J. A. and Ivie, G. W. Systemic Activity of Coumaphos, Famphur, Crufomate, Ronnel, and Phosmet 

Given Orally to Hens for Control of the Northern Fowl Mite, Ornithonyssus sylviarum (Canestrini 

and Fanzago). Poult. Sci.; 1980; 59, 1208-1210. 

Notes: EcoReference No.: 48673 

Chemical of Concern: CMPH,PSM 

 6. Drummond, R. O. Susceptibility of the Cayenne Tick to Acaricides. J. Econ. Entomol.; 1981; 74, (4): 470-

472. 

Notes: EcoReference No.: 113468 

Chemical of Concern: AMZ,AsTO,CBL,CMPH,CPY,DDT,DZ,ETN,FNTH,HCCH,MLN,PPCP, 

PPHD,PSM,TCF,TVP,TXP 

 7. Drummond, R. O.; Gladney, W. J.; Whetstone, T. M., and Ernst, S. E. Laboratory Testing of Insecticides for 

Control of the Winter Tick. J. Econ. Entomol.; 1971; 64, (3): 686-688. 

Notes: EcoReference No.: 113239 

Chemical of Concern: 

As,CBL,CMPH,CPY,DZ,ETN,FNTH,HCCH,MLN,PPCP,PPHD,PPX,PSM,RTN,TCF,TVP,TXP 

 8. ---. Testing of Insecticides Against the Tropical Horse Tick in the Laboratory. J. Econ. Entomol.; 1971; 64, 

(5): 1164-1166. 

Notes: EcoReference No.: 113240 

Chemical of Concern: As,CBL,CMPH,CPY,DZ,ETN,FNTH,HCCH,MLN,PPCP,PPHD,PPX, 

PSM,TCF,TVP,TXP 

 9. Elzen, P. J.; Westervelt, D., and Lucas, R. Formic Acid Treatment for Control of Varroa destructor 

(Mesostigmata: Varroidae) and Safety to Apis mellifera (Hymenoptera: Apidae) Under Southern 

United States Conditions. J. Econ. Entomol.; 2004; 97, (5): 1509-1512. 

Notes: EcoReference No.: 100404 

Chemical of Concern: CMPH,FMA 
101 

 10. Gregorc, A. and Ellis, J. D. Cell Death Localization In Situ in Laboratory Reared Honey Bee (Apis mellifera 

L.) Larvae Treated with Pesticides. Pestic. Biochem. Physiol.; 2011; 99, (2): 200-207. 

Notes: EcoReference No.: 156418 

Chemical of Concern: AMZ,CMPH,CPY,CTN,FVL,GYP,IMC,MYC,SZ 

 11. Gregorc, A.; Evans, J. D.; Scharf, M., and Ellis, J. D. Gene Expression in Honey Bee (Apis mellifera) Larvae 

Exposed to Pesticides and Varroa mites (Varroa destructor). J. Insect Physiol.; 2012; 58, (8): 1042-

1049. 

Notes: EcoReference No.: 157769 

Chemical of Concern: AMZ,CMPH,CPY,CTN,FVL,GYP,IMC,MYC,SZ 

 12. Johnson, R. M.; Pollock, H. S., and Berenbaum, M. R. Synergistic Interactions Between In-Hive Miticides in 

Apis mellifera. J. Econ. Entomol.; 2009; 102, (2): 474-479. 

Notes: EcoReference No.: 119503 

Chemical of Concern: CMPH,PPB,TAUF,TBF 

 13. Karabacak, M.; Kanbur, M.; Eraslan, G., and Sarica, Z. S. The Antioxidant Effect of Wheat Germ Oil on 

Subchronic Coumaphos Exposure in Mice. Ecotoxicol. Environ. Saf.; 2011; 74, (7): 2119-2125. 

Notes: EcoReference No.: 157622 

Chemical of Concern: CMPH 

 14. Kitchin, K. T. and Brown, J. L. Biochemical Studies of Promoters of Carcinogenesis in Rat Liver. Teratog. 

Carcinog. Mutagen.; 1989; 9, (5): 273-285. 

Notes: EcoReference No.: 103823 

Chemical of Concern: CMPH,EDTA,MRX,TXP 

 15. Koch, H. G. and Burkwhat, H. E. Susceptibility of the American Dog Tick (Acari: Ixodidae) to Residues of 

Acaricides: Laboratory Assays. J. Econ. Entomol.; 1983; 76, (2): 337-339. 

Notes: EcoReference No.: 113231 

Chemical of Concern: AMZ,ATN,BDC,CBL,CHD,CMPH,CPY,DZ,FNTH,HCCH, MLN,MXC, 

Naled,PMR,PPCP,PPX, PSM,RSM,RTN,TCF,TVP,TXP 

 16. Miller, J. E. Epidemiology and Economics of Strongylate Nematode Parasites of the Bovine in Central 

California. Ph.D. Thesis, University of California, Davis, CA; 1983: 217 p. (UMI# 407917). 

Notes: EcoReference No.: 157924 

Chemical of Concern: CMPH,TBA 

 17. Miller, R. W.; Gordon, C. H.; Morgan, N. O.; Bowman, M. C., and Beroza, M. Coumaphos as a Feed 

Additive for the Control of House Fly Larvae in Cow Manure. J. Econ. Entomol.; 1970; 63, (3): 

853-855. 

Notes: EcoReference No.: 103849 

Chemical of Concern: CMPH 

 18. Robbins, W. E.; Hopkins, T. L., and Darrow, D. I. Synergistic Action of Piperonyl Butoxide with Bayer 

21/199 and Its Corresponding Phosphate in Mice. J. Econ. Entomol.; 1959; 52, 660-663. 

Notes: EcoReference No.: 157619 

Chemical of Concern: CMPH,CMPO,PPB 

 19. Smodis Skerl, M. I. and Gregorc, A. Heat Shock Proteins and Cell Death In Situ Localisation in 

Hypopharyngeal Glands of Honeybee (Apis mellifera carnica) Workers After Imidacloprid or 

Coumaphos Treatment. Apidologie; 2010; 41, (1): 73-86. 

Notes: EcoReference No.: 157832 

Chemical of Concern: CMPH,IMC 

 20. Su, M. Q.; Kinoshita, F. K.; Frawley, J. P., and DuBois, K. P. Comparative Inhibition of Aliesterases and 
102 

Cholinesterase in Rats Fed Eighteen Organophosphorus Insecticides. Toxicol. Appl. Pharmacol.; 

1971; 20, (2): 241-249. 

Notes: EcoReference No.: 38991 

Chemical of Concern: AZ,CMPH,DEM,DMT,DS,EPRN,ETN,FNTH,MLN,MP,MVP,PRN 

 21. Takagi, H. and Block, E. Effects of Feeding Coumaphos to Dairy Cows at Various Stages of Lactation on 

Subclinical Parasite Infection and Milk Production. Can. J. Anim. Sci.; 1986; 66, (1): 141-150. 

Notes: EcoReference No.: 101801 

Chemical of Concern: CMPH 

 22. White, R. D. Mutagenic and Toxicologic Implications of Pyrrolizidine (Senecio) Alkaloids. Ph.D. Thesis, 

Oregon State University, OR; 1983: 105 p. (UMI# 8227585) (Publ. in part as 118136, 157929). 

Notes: EcoReference No.: 157925 

Chemical of Concern: CBL,CMPH,Cu,MLN,PPCP 

April 2008 search 

1. Astroff, A. B.; Freshwater, K. J., and Eigenberg, D. A. Comparative Organophosphate-Induced Effects 

Observed in Adult and Neonatal Sprague-Dawley Rats During the Conduct of Multigeneration Toxicity 

Studies. Reprod. Toxicol.; 1998; 12, (6): 619-645. 

Notes: EcoReference No.: 88895 

Chemical of Concern: TCF,TBF,OXD,FMP,CMPH 

 2. Brody, G. and Elward, T. E. Comparative Activity of 29 Known Anthelmintics Under Standarized Drug-Diet 

and Gavage Medication Regimens Against Four Helminth Species in Mice. J. Parasitol.; 1971; 57, 

(5): 1068-1077. 

Notes: EcoReference No.: 101241 

Chemical of Concern: DDVP,CMPH,NSM,TBA,TCF 

 3. Carlson, C. A. Effects of Three Organophosphorus Insecticides on Immature Hexagenia and Hydropsyche of 

the Upper Mississippi River. Trans. Am. Fish. Soc.; 1966; 95, (1): 1-5. 

Notes: EcoReference No.: 2158 

Chemical of Concern: CMPH,MLN 

 4. Collins, A. M.; Pettis, J. S.; Wilbanks, R., and Feldlaufer, M. Performance of Honey Bee (Apis mellifera) 

Queens Reared in Beeswax Cells Impregnated with Coumaphos. J. Apic. Res.; 2004; 43, (3): 128-

134. 

Notes: EcoReference No.: 100380 

Chemical of Concern: CMPH 

 5. Cox, D. D.; Mullee, M. T., and Allen, A. D. Anthelmintic Activity of Two Organic Phosphorus Compounds, 

Coumaphos and Naphthalophos, Against Gastrointestinal Nematodes of Cattle. Am. J. Vet. Res.; 

1967; 28, (122): 79-88. 

Notes: EcoReference No.: 100916 

Chemical of Concern: CMPH 

 6. ---. Cattle Grub Control with Feed Additives (Coumaphos and Fenthion) and Pour-ons (Fenthion and 

Trichlorfon). J. Econ. Entomol.; 1967; 60, (2): 522-527. 

Notes: EcoReference No.: 101195 

Chemical of Concern: TCF,FNTH,CMPH 

 7. ---. Effect of Coumaphos and Fenthion Feed Additives on Gastrointestinal Nematode Egg Counts in Feedlot 

Cattle. Am. J. Vet. Res.; 1969; 30, (11): 1933-1943. 

Notes: EcoReference No.: 100914 

Chemical of Concern: CMPH,FNTH 
103 

 8. Davis, H. C. and Hidu, H. Effects of Pesticides on Embryonic Development of Clams and Oysters and on 

Survival and Growth of the Larvae. Fish. Bull.; 1969; 67, (2): 393-404. 

Notes: EcoReference No.: 2400 

Chemical of Concern: EDT,24DXY,AZ,CBL,CMPH,DS,DU,HCCH,MLN,PCP,PRN, DDT,NaPCP, 

DZ, DBAC,DCB,TCC 

 9. Dawe, D. L.; Brown, J.; Davis, R. B., and Kellogg, F. E. Effectiveness of Maretin and Meldane as Treatments 

for Capillariasis in Bobwhites. Avian Dis.; 1969; 13, (3): 662-667. 

Notes: EcoReference No.: 101108 

Chemical of Concern: CMPH 

 10. Elzen, P. J. Suitability of Formic Acid to Control Varroa destructor and Safety to Apis mellifera in the 

Southwestern U.S. Southwest. Entomol.; 2003; 28, (4): 261-266. 

Notes: EcoReference No.: 101098 

Chemical of Concern: FMA,CMPH,FVL 

 11. Faulkner, L. C.; Carroll, E. J., and Benjamin, M. Effect of Coumaphos on Bulls. J. Am. Vet. Med. Assoc.; 

1964; 145, (5): 456-459. 

Notes: EcoReference No.: 101192 

Chemical of Concern: CMPH 

 12. Folz, S. D.; Pax, R. A.; Thomas, E. M.; Bennett, J. L.; Lee, B. L., and Conder, G. A. Detecting In Vitro 

Anthelmintic Effects with a Micromotility Meter. Vet. Parasitol.; 1987; 24, (3/4): 241-250. 

Notes: EcoReference No.: 101182 

Chemical of Concern: CMPH 

 13. ---. Development and Validation of an In Vitro Trichostrongylus colubriformis Motility Assay. Int. J. 

Parasitol.; 1987; 17, (8): 1441-1444. 

Notes: EcoReference No.: 101170 

Chemical of Concern: CMPH 

 14. Glenn, J. S.; Baker, N. F.; Franti, C. E., and Ver Steeg, J. D. Anthelmintic Treatment of Nonpastured Dairy 

Cows in California. J. Dairy Sci.; 1982; 65, (10): 2006-2010. 

Notes: EcoReference No.: 101239 

Chemical of Concern: CMPH 

 15. Haarmann, T.; Spivak, M.; Weaver, D.; Weaver, B., and Glenn, T. Effects of Fluvalinate and Coumaphos on 

Queen Honey Bees (Hymenoptera: Apidae) in Two Commercial Queen Rearing Operations. J. 

Econ. Entomol.; 2002; 95, (1): 28-35. 

Notes: EcoReference No.: 66848 

Chemical of Concern: FVL,CMPH 

 16. Heath, R. G. ; Spann, J. W.; Hill, E. F., and Kreitzer, J. F. Comparative Dietary Toxicities of Pesticides to 

Birds. pecial Scientific Report Wildlife 152, Bureau of Sport Fisheries and Wildlife, U.S. 

Department of the Interior, Washington, DC; 1972: 57 p. 

Notes: EcoReference No.: 35214 

Chemical of Concern: TMP,AND,AMTL,ATZ,PPX,Captan,CHL,CHD,TCF,24DXY,DDT,24DB, 

DDVP,DEM,DEZ,DBN,DCF,DLD,DS,CU,CPY,DMT,SZ,FNF,ES,EN,TXP,FNT,FNTH,AZ,HPT,P

SM,HCCH,MLN,MCPB,MTAS,MOM,MXC,MP,MRX,Nabam,Naled,OXC,PRN,PCP,PRT,PPHD,

PCL,TFM,THM,PPG,CMPH,OXD,DZ 

 17. Hill, E. F. and Camardese, M. B. Lethal Dietary Toxicities of Environmental Contaminants and Pesticides to 

Coturnix. Lethal Dietary Toxicities of Environmental Contaminants and Pesticides to Coturnix; 

1986: 147 p. 

Notes: EcoReference No.: 50181 
104 

Chemical of Concern: 24D,24DXY,ACP,ADC,AMSV,AMTL,AND,ARM,ATN,ATZ,AZ,BMC, 

BMN,BMY,Captan,CBF,CBL,CdCl,CHD,CMPH,CPY,CPYM,CrS,DBN,DCF,DCTP,DDT,DDVP,

DEM,DFPM,DINO,DLD,DMB,DMT,DQTBr,DS,DU,DZ,EN,EP,ES,ETN,FMP,FNF,FNT,FNTH,F

TTCl,GYP,HCCH,HgCl2,HPT,IFP,K2Cr207,LNR,Maneb,MCB,MCPB,MDT,MLN,MLT,MOM,M

P,MRX,MSMA,MTAS,MTM,MVP,MXC,Naled,Ni,OXD,Pb,PbN,PCB,PCL,PCP,PHSL,PMR,PPB,

PPHD,PPN,PPX,PQT,PRN,PRT,PSM,PYN,RSM,RTN,SPS,SZ,TBO,TCF,TEPP,TFN,THM,TMP,T

VMP, TVP,V,Zineb,Ziram,ZnP 

 18. Hill, E. F.; Heath, R. G.; Spann, J. W., and Williams, J. D. Lethal Dietary Toxicities of Environmental 

Pollutants to Birds. U.S.Fish and Wildl.Serv.No.191, Special Scientific Report-Wildlife; 1975: 61 p. 

Notes: EcoReference No.: 35243 

Chemical of Concern: 24DXY,TMP,ADC,AMTL,AND,ATZ,Captan,CBF,CBL,Cd,Cr,DDT,DLD, 

DMT,DS,DU,DZ,ES,ETN,FNT,HCCH,Hg,HPT,MCPB,MLN,MP,MRX,MTAS,MXC,Naled,Pb,PC

B,PCL,PCP,PQT,PRN,PRT,PYN,RSM,RTN,SZ,TFM,THM,TVP,TXP,Zn,ZnP,As,AZ,OXD,PSM,L

NR,PPG,CYP,PEM,MOM,DDVP,PHTH,DBN,CMPH,TVPM 

 19. Hudson, R. H.; Tucker, R. K., and Haegele, M. A. Handbook of Toxicity of Pesticides to Wildlife. Resource 

Publication 153, Fish and Wildlife Service, U.S. Department of the Interior; 1984: 90 p. 

Notes: EcoReference No.: 50386 

Chemical of Concern: ACP,ACL,ACR,ADC,AND,ATN,AMTL,ANZ,ATZ,4AP,AZ,PPX,BTY, 

Captan,CBL,CBF,CHD,CQTC,CPY,CMPH,CZE,24D,DDT,DDVP,DEF,DEM,DZ,DBN,DLN,DCF,

DCTP,DLD,DMT,DQTBr,DS,DU,ES,EDT,EN,EP,ETN,FNT,FNTH,FMV,Folpet,FNF,HPT,PSM,H

CCH,MLN,MDT,MCB,MOM,MTPN,MXC,MP,MVP,MRX,NABAM,Naled,FMP,PQT,PRN,PCP,P

RT,PCL,PSM,RTN,STAR,STCH,TCDD,TMP,TZL,TVP,TZL,THM,TXP,TCF,TFN,ZnP,Zineb,PC

B 

 20. Katz, M. Acute Toxicity of Some Organic Insecticides to Three Species of Salmonids and to the Threespine 

Stickleback. Trans. Am. Fish. Soc.; 1961; 90, (3): 364-368. 

Notes: EcoReference No.: 522 

Chemical of Concern: CMPH,TXP,AND,DLD,DDT,HCCH,MXC,HPT,CHD,EN,AZ,MLN,CBL 

 21. Knapp, F. W. The Effect of Free-Choice Coumaphos Salt Mixtures on Cattle and Cattle Parasites. J. Econ. 

Entomol.; 1965; 58, (2): 197-199. 

Notes: EcoReference No.: 101238 

Chemical of Concern: CMPH 

 22. Landrum, P. F.; Fisher, S. W.; Hwang, H., and Hickey, J. Hazard Evaluation of Ten Organophosphorus 

Insecticides Against the Midge, Chironomus riparius via QSAR. MOR. P.F.Landrum, Great Lakes 

Environmental Research Laboratory, NOAA, Ann Arbor, MI, 48105: SAR QSAR Environ.Res.; 

1999; 10, (5): 423-450. 

Notes: EcoReference No.: 67687 

Chemical of Concern: FNF,TBO,CMPH,DCTP,FNTH,AZ,CPY,DZ,DS 

 23. Leland, S. E. Jr.; Ridley, R. K.; Dick, J. W.; Slonka, G. F., and Zimmerman, G. L. Anthelmintic Activity of 

Trichlorfon, Coumaphos, and Naphthalophos Against the In Vitro Grown Parasitic Stages of 

Cooperia punctata. J. Parasitol.; 1971; 57, (6): 1190-1197. 

Notes: EcoReference No.: 101240 

Chemical of Concern: TCF,CMPH 

 24. Maronpot, R. R.; Shimkin, M. B.; Witschi, H. P.; Smith, L. H., and Cline, J. M. Strain A Mouse Pulmonary 

Tumor Test Results for Chemicals Previously Tested in the National Cancer Institute 

Carcinogenicity Tests. MOR,PHYINJECT; 1986; 76, (6): 1101-1112. 

Notes: EcoReference No.: 91262 

Chemical of Concern: Captan,DZ,PRN,AND,EDB,TXP,CMPH,DNT 

 25. Miller, J. E.; Baker, N. F., and Farver, T. B. Anthelmintic Treatment of Pastured Dairy Cattle in California. 
105 

Am. J. Vet. Res.; 1986; 47, (9): 2036-2040. 

Notes: EcoReference No.: 101152 

Chemical of Concern: TBA,CMPH 

 26. Miller, R. W. and Long, P. P. Effect of Feeding Coumaphos on Feed Intake and Rate of Gain of Steers. J. 

Dairy Sci.; 1974; 57, (6): 723-725. 

Notes: EcoReference No.: 37967 

Chemical of Concern: CMPH 

 27. National Cancer Institute. Bioassay of Coumaphos for Possible Carcinogenicity. NCI Tech.Rep.Ser.#96, 

Natl.Cancer Inst., Bethesda, MD; 1979: 100 p. 

Notes: EcoReference No.: 100567 

Chemical of Concern: CMPH 

 28. Nelson, D. L.; Mozier, J. O.; White, R. G., and Allen, A. D. The Pharmacological Effect of Baymix 

(Coumaphos) on Poultry. Poult. Sci.; 1968; 47, (3): 960-962. 

Notes: EcoReference No.: 101256 

Chemical of Concern: CMPH 

 29. Pardio, V. T.; De Ibarra, N. J.; Waliszewski, K. N., and Lopez, K. M. Effect of Coumaphos on Cholinesterase 

Activity, Hematology, and Biochemical Blood Parameters of Bovines in Tropical Regions of 

Mexico. J. Environ. Sci. Health Part B: Pestic. Food Contam. Agric. Wastes; 2007; 42, (4): 359-

366. 

Notes: EcoReference No.: 100839 

Chemical of Concern: CMPH 

 30. Pardio, V. T.; Ibarra, N.; Rodriguez, M. A., and Waliszewski, K. N. Use of Cholinesterase Activity in 

Monitoring Organophosphate Pesticide Exposure of Cattle Produced in Tropical Areas. J. Agric. 

Food Chem.; 2001; 49, (12): 6057-6062. 

Notes: EcoReference No.: 100382 

Chemical of Concern: FNTH,CMPH 

 31. Pettis, J. S.; Collins, A. M.; Wilbanks, R., and Feldlaufer, M. F. Effects of Coumaphos on Queen Rearing in 

the Honey Bee, Apis mellifera. Apidologie; 2004; 35, (6): 605-610. 

Notes: EcoReference No.: 100910 

Chemical of Concern: CMPH 

 32. Rettich, F. Laboratory and Field Investigations in Czechoslovakia with Fenitrothion, Pirimiphos-Methyl, 

Temephos and Other Organophosphorous Larvicides. Mosq. News; 1979; 39, (2): 320-328 (Author 

Communication Used). 

Notes: EcoReference No.: 5162 

Chemical of Concern: CPY,DZ,MLN,CMPH,DMT,Naled,DDT,FNT,PIRM,TMP,TCF,DDVP,TVP 

 33. Sanchez-Fortun, S.; Sanz-Barrera, F., and Barahona-Gomariz, M. V. Acute Toxicities of Selected Insecticides 

to the Aquatic Arthropod Artemia salina. Bull. Environ. Contam. Toxicol.; 1995; 54, (1): 76-82. 

Notes: EcoReference No.: 14997 

Chemical of Concern: CMPH,AZ,DDVP,DDT,DLD,HCCH 

 34. Sanders, H. O. Toxicity of Some Insecticides to Four Species of Malacostracan Crustaceans. 

Tech.Pap.No.66, Bur.Sports Fish.Wildl., Fish Wildl.Serv., U.S.D.I., Washington, D.C.; 1972: 19 p. 

(Publ in Part As 6797). 

Notes: EcoReference No.: 887 

Chemical of Concern: ATN,ES,AZ,MLN,MXC,Naled,DS,PRT,CBL,DLD,EN,CHD,AND,DDT, 

TXP,HPT,CPY,CMPH,OXD,DZ 
106 

 35. Silvestri, R.; Himes, J. A., and Edds, G. T. Repeated Oral Administration of Coumaphos in Sheep: Effects on 

Erythrocyte Acetylcholinesterase and Other Constituents. Am. J. Vet. Res.; 1975; 36, (3): 283-287. 

Notes: EcoReference No.: 38777 

Chemical of Concern: CMPH 

 36. Van Buren, N. W. M.; Marien, A. G. H.; Oudejans, R. C. H. M., and Velthuis, H. H. W. Perizin, an Acaricide 

to Combat the Mite Varroa jacobsoni: Its Distribution in and Influence on the Honeybee Apis 

mellifera. Physiol. Entomol.; 1992; 17, (3): 288-296. 

Notes: EcoReference No.: 101175 

Chemical of Concern: CMPH 

 37. Weick, J. and Thorn, R. S. Effects of Acute Sublethal Exposure to Coumaphos or Diazinon on Acquisition 

and Discrimination of Odor Stimuli in the Honey Bee (Hymenoptera: Apidae). MOR,BCM,BEH. 

J.Weick, Dep. of Biol., Denison Univ., Granville, OH 43203: J. Econ. Entomol.; 2002; 95, (2): 227-

236. 

Notes: EcoReference No.: 87972 

Chemical of Concern: CMPH,DZ 

 38. Willford, W. A. Toxicity of 22 Therapeutic Compounds to Six Fishes. Invest.Fish Control No.18, 

Resourc.Publ.No.35, Fish Wildl.Serv., Bur.Sport Fish.Wildl., USDI, Washington, DC; 1966: 10 p. 

Notes: EcoReference No.: 2524 

Chemical of Concern: CMPH,Ni,DBAC 

 39. Wilton, D. P.; Fetzer, L. E. Jr., and Fay, R. W. Insecticide Baits for Anopheline Larvae. Mosq. News; 1973; 

33, (2): 198-203. 

Notes: EcoReference No.: 13956 

Chemical of Concern: FNTH,FNT,CMPH,CBL,MXC,MCB,CPY,RSM,CPYM,TMP 

 
107 

Appendix D: ECOTOX Literature Search – Papers That Were Not 

Acceptable 

April 2012 refresh 

 1. Alabaster, J. S. Survival of Fish in 164 Herbicides, Insecticides, Fungicides, Wetting Agents and 

Miscellaneous Substances. MORAQUA; 1969; 11, (2): 29-35 (Author Communication Used). 

Notes: EcoReference No.: 542 

Chemical of Concern: 

24D,24DXY,24DXYBEE,ACHY,ACL,AMTL,ATZ,BHAP,BOR,BORON,BRA,BSN881,CAP,CM

PH,CPA,CuOX,DBN,DDT,DINO,DIOSSNa,DQTBr,DZ,DZM,FUR,MCPP1,MEM,MLH,MTAS,N

aClO,NaDPA,NaDSS,NaPCP,PCLK,PL,PQT,PYZ,SZ,TBTO,TFN,TRL 

 2. Aziz, S. A. Toxicity of Certain Insecticide Standards Against the Southern Armyworm. MORTOP; 1973; 66, 

(1): 68-70. 

Notes: EcoReference No.: 112632 

Chemical of Concern: 

ADC,AND,AZ,CBF,CBL,CMPH,CPY,DDT,DDVP,DEM,DLD,DMT,DS,DZ,EN,EPRN,HCCH,HP

T,MP,MVP,PPCP,PRN,PRT,PSM,TCF,TMP,TXP 

 3. Bacandritsos, N.; Papanastasiou, I.; Saitanis, C.; Nanetti, A., and Roinioti, E. Efficacy of Repeated Trickle 

Applications of Oxalic Acid in Syrup for Varroosis Control in Apis mellifera: Influence of 

Meteorological Conditions and Presence of Brood. MOR,POPENV,MIXTURE; 2007; 148, (2): 

174-178. 

Notes: EcoReference No.: 151746 

Chemical of Concern: CMPH,OXAC 

 4. Beatty, J. F.; Arnold, B. L.; McGee, W. H.; Custer, E. W., and Daniels, J. W. The Effect of "Baymix" on 

Milk Production and Milk Quality. PHY,REP. Mississippi Agricultural and Forestry Experiment 

Station//: ORAL; 1974; 37, (9): 8. 

Notes: EcoReference No.: 157765 

Chemical of Concern: CMPH 

 5. Beugnet, F. and Chardonnet, L. Tick Resistance to Pyrethroids in New Caledonia. MORENV; 1995; 56, (4): 

325-338. 

Notes: EcoReference No.: 115241 

Chemical of Concern: CMPH,CPY,DM,DZ,ETN,FNTH,FNV,PTP 

 6. Bonzini, S.; Tremolada, P.; Bernardinelli, I.; Colombo, M., and Vighi, M. Predicting Pesticide Fate in the 

Hive (Part 1): Experimentally Determined Tau-Fluvalinate Residues in Bees, Honey and Wax. 

ACC. [Tremolada, P] Univ Milan, Dept Biol, I-20133 Milan, Italy//: ENV; 2011; 42, (3): 378-390. 

Notes: EcoReference No.: 157830 

Chemical of Concern: AMZ,CMPH,MLN,PMR,TAUF 

 7. Burley, L. M.; Fell, R. D., and Saacke, R. G. Survival of Honey Bee (Hymenoptera: Apidae) Spermatozoa 

Incubated at Room Temperature from Drones Exposed to Miticides. POP,REP. lmburley@vt.edu//: 

ENV; 2008; 101, (4): 1081-1087. 

Notes: EcoReference No.: 107876 

Chemical of Concern: CMPH,TAUF,TML 

 8. Butler, P. A. Commercial Fishery Investigations. ACC,BEH,GRO,MOR,PHY,POP,SYSAQUA; 1964: 28 p. 

(Author Communication Used). 

Notes: EcoReference No.: 646 

Chemical of Concern: 
108 

24DXY,24DXYBEE,24DXYEE,AND,ANZ,AZ,CBL,CMPH,DCPA,DCTP,DDT,DDVP,DEM,DLD

,DMDP,DMT,DQT,DQTBr,DS,DU,EN,EPRN,EPTC,ES,ETN,FNT,FNTH,HCCH,HPT,MCB,MCP

AD,MLN,MP,MRX,MVP,MXC,NTP,Naled,PAQT,PEB,PPCP,PPHD,PPX,PQT,PRN,PRT,PSM,TB

F,TCF,TMP,TVP,TXP 

 9. Byford, R. L. ; Sparks, T. C.; Green, B.; Knox, J., and Wyatt, W. Organophosphorus Insecticides for the 

Control of Pyrethroid-Resistant Horn Flies (Diptera: Muscidae). MOR,POPENV,MIXTURE,TOP; 

1988; 81, (6): 1562-1566. 

Notes: EcoReference No.: 114522 

Chemical of Concern: CMPH,CPY,DMT,DZ,ETN,FNV,MLN,PIRM,PMR,TCF,TVP 

 10. Castella, J. and Estrada, A. Susceptibility of the Brown Dog Tick to Eight Acaricides, 1991. MORTOP; 

1994; 19, 371-(4L). 

Notes: EcoReference No.: 106250 

Chemical of Concern: AMZ,CMPH,CYP,DM,DZ,PMR 

 11. Dorough, H. W.; Brady, U. E. Jr.; Timmerman, J. A., and Arthur, B. W. Residues in Tissues and Eggs of 

Poultry Receiving Co-Ral (Bayer 21/199) in the Feed. ACC,REPORAL; 1961; 54, 97-100. 

Notes: EcoReference No.: 103834 

Chemical of Concern: CMPH 

 12. Drummond, R. O. Susceptibility of the Gulf Coast Tick (Acari: Ixodidae) to Acaricides. REPTOP; 1988; 81, 

(4): 1140-1142. 

Notes: EcoReference No.: 114521 

Chemical of Concern: AMZ,AsTO,CBL,CMPH,CPY,DZ,HCCH,MLN,PMR,PPCP,PSM,TVP,TXP 

 13. Drummond, R. O.; Ernst, S. E.; Trevino, J. L., and Graham, O. H. Insecticides for Control of the Cattle Tick 

and the Southern Cattle Tick on Cattle. POPTOP; 1968; 61, (2): 467-470. 

Notes: EcoReference No.: 113241 

Chemical of Concern: CBL,CMPH,CPY,DZ,ETN,FNTH,PPX,PSM 

 14. Drummond, R. O.; Whetstone, T. M.; Ernst, S. E., and Gladney, W. J. Control of Three-Host Ticks. 

Laboratory Tests of Systemic Insecticides in Feed of Cattle. MOR,PHY,POP,REPENV,ORAL; 

1972; 65, (6): 1641-1644. 

Notes: EcoReference No.: 114791 

Chemical of Concern: CMPH,FNTH,PSM 

 15. Drummond, R. O.; Whetstone, T. M.; Shelley, B. K., and Barrett, C. C. Common Cattle Grub: Control with 

Animal Systemic Insecticides. MOR,POPENV; 1977; 70, (2): 176-178. 

Notes: EcoReference No.: 113371 

Chemical of Concern: CMPH,FNTH,MTPN,PSM,TCF 

 16. Gladney, W. J.; Ernst, S. E.; Dawkins, C. C.; Drummond, R. O., and Graham, O. H. Feeding Systemic 

Insecticides to Cattle for Control of the Tropical Horse Tick. GRO,MOR,POP,REPENV; 1972; 9, 

(5): 439-442. 

Notes: EcoReference No.: 115592 

Chemical of Concern: CMPH,FNTH,PSM 

 17. Gregorc, A. and Planinc, I. The Control of Varroa destructor Using Oxalic Acid. POPENV,MIXTURE; 

2002; 163, (3): 306-310. 

Notes: EcoReference No.: 151669 

Chemical of Concern: CMPH,OXAC 

 18. Gregorc, A. and Poklukar, J. Rotenone and Oxalic Acid as Alternative Acaricidal Treatments for Varroa 

destructor in Honeybee Colonies. MOR,POPENV,MIXTURE; 2003; 111, (4): 351-360. 
109 

Notes: EcoReference No.: 76055 

Chemical of Concern: CMPH,OXAC,RTN 

 19. Hansen, M. F. and Zeakes, S. M. Efficacy of Maretin and Baymix Against Nematodes of Calves. POPENV; 

1969; 88, (1): 159-161. 

Notes: EcoReference No.: 157729 

Chemical of Concern: CMPH 

 20. Higes, M.; Meana, A.; Suarez, M., and Llorente, J. Negative Long-Term Effects on Bee Colonies Treated 

with Oxalic Acid Against Varroa jacobsoni Oud. MOR,POP,REP. Dpto. Patologia Animal I 

(Sanidad Animal//: ENV; 1999; 30, (4): 289-292. 

Notes: EcoReference No.: 151761 

Chemical of Concern: CMPH,OXAC,TAUF 

 21. Hughes, P. B. and Devonshire, A. L. The Biochemical Basis of Resistance to Organophosphorus Insecticides 

in the Sheep Blowfly, Lucilia cuprina. ACC,MOR,PHYTOP; 1982; 18 , 289-297. 

Notes: EcoReference No.: 71995 

Chemical of Concern: CMPH,DZ,EPRN,PRN 

 22. Jones, K. H.; Sanderson, D. M., and Noakes, D. N. Acute Toxicity Data for Pesticides (1968). 

MORORAL,TOP; 1968; 7, (3): 135-143. 

Notes: EcoReference No.: 70074 

Chemical of Concern: 

24DXY,ABT,ACL,ADC,AMTL,AMTR,AND,ASM,ATN,ATZ,AZ,BFL,BMC,BMN,BS,BTY,CBL,

CCA,CHD,CMPH,CPP,CPY,CQTC,CTHM,Captan,Cu,CuFRA,DBN,DCB,DCNA,DCPA,DDD,DD

T,DDVP,DEM,DINO,DLD,DMB,DMT,DOD,DPP,DQTBr,DS,DU,DZ,DZM,EDT,EN,EP,EPRN,E

PTC,ES,ETN,FLAC,FMU,FNF,FNT,FNTH,Folpet,HCCH,HPT,LNR,MCB,MCPA,MCPB,MCPP1,

MDT,MLH,MLN,MLT,MRX,MTM,MVP,MXC,Maneb,NPM,Naled,PCH,PCL,PCP,PEB,PHMD,P

HSL,PMT,PPCP,PPHD,PPN,PPX,PPZ,PQT,PRN,PRO,PRT,PYN,PYZ,Pb,RTN,SFT,SID,SZ,TCF,T

FN,THM,TRB,TRL,TXP,VNT,Zineb 

 23. Kaplanis, J. N.; Hopkins, D. E., and Treiber, G. H. Dermal and Oral Treatments of Cattle with Phosphorus32-Labeled Co-Ral. ACCTOP; 1959; 7, (7): 483-486. 

Notes: EcoReference No.: 157621 

Chemical of Concern: CMPH 

 24. Kitchin, K. T.; Brown, J. L., and Kulkarni, A. P. Ornithine Decarboxylase Induction and DNA Damage as a 

Predictive Assay for Potential Carcinogenicity. BCM,CELORAL; 1991; 369, 137-144 (Publ in part 

as 103823). 

Notes: EcoReference No.: 103822 

Chemical of Concern: CMPH,DDE 

 25. ---. Predicting Rodent Carcinogenicity of Halogenated Hydrocarbons by In Vivo Biochemical Parameters. 

BCM,CEL,MORORAL; 1993; 13, (4): 167-184. 

Notes: EcoReference No.: 70486 

Chemical of Concern: 

13DPE,24D,24DXY,CF,CMPH,CQTC,CTC,DCB,DDE,DDT,DDVP,DPDP,DXN,EDB,EN,MRX,P

BDE,PNB,TCDD,TXP 

 26. Kraus, B. and Berg, S. Effect of a Lactic Acid Treatment During Winter in Temperate Climate upon Varroa 

jacobsoni Oud. and the Bee (Apis mellifera L.) Colony. BEH,MOR,POP,REPENV,MIXTURE; 

1994; 18, (8): 459-468. 

Notes: EcoReference No.: 100418 

Chemical of Concern: CMPH,LLA 
110 

 27. Krueger, H. R.; Casida, J. E., and Niedermeier, R. P. Animal Metabolism of Insecticides. Bovine Metabolism 

of Organphosphorus Insecticides. Metabolism and Residues Associated with Dermal Application of 

Co-ral to Rats, a Goat, and a Cow. ACC,BCMTOP; 1959; 7, (3): 182-188. 

Notes: EcoReference No.: 157620 

Chemical of Concern: CMPH 

 28. Lammler, G. and Gruner, D. Chemotherapeutic Studies on Litomosoides carinii Infection of Mastomys 

natalensis. 6. The Filaricidal Activity of Organophosphorus Compounds. POPINJECT,ORAL; 

1975; 26, (3): 359-369. 

Notes: EcoReference No.: 104001 

Chemical of Concern: CMPH,CPY,FNTH,PSM,TCF 

 29. Li, A. Y.; Pruett, J. H.; Davey, R. B., and George, J. E. Toxicological and Biochemical Characterization of 

Coumaphos Resistance in the San Roman Strain of Boophilus microplus (Acari: Ixodidae). 

BCM,MORTOP; 2005; 81, (3): 145-153. 

Notes: EcoReference No.: 80229 

Chemical of Concern: 3CE,CMPH,PPB 

 30. Mao, W.; Schuler, M. A., and Berenbaum, M. R. CYP9Q-Mediated Detoxification of Acaricides in the 

Honey Bee (Apis mellifera). CEL. Department of Entomology, University of Illinois, Urbana, IL 

61801, USA.//: TOP; 2011; 108, (31): 12657-12662. 

Notes: EcoReference No.: 156538 

Chemical of Concern: BFT,CMPH,CYP,TAUF 

 31. Mayer, F. L. Jr. Acute Toxicity Handbook of Chemicals to Estuarine Organisms. 

GRO,MOR,PHY,POPAQUA; 1987: 274 p. 

Notes: EcoReference No.: 3947 

Chemical of Concern: 

24D,24DC,24DXY,24DXYBEE,ACD,ACL,ACP,ADC,ALSV,AMTR,AND,ANZ,ATM,ATZ,AZ,A

gN,AsTO,BMC,BS,CAP,CBF,CBL,CCA,CHD,CMPH,CPY,CST,CTN,CYP,Captan,CdCl,DBN,DC

F,DCPA,DCTP,DDE,DDT,DDVP,DEM,DFZ,DLD,DMB,DMT,DQTBr,DS,DSMA,DU,DZ,EDT,E

N,EP,EPRN,EPTC,ES,ETN,FBM,FMP,FNF,FNT,FNTH,HCB,HCCH,HCCP,HMN,HPT,HgCl2,K2

Cr2O7,MCB,MDT,MLN,MLT,MP,MRX,MTAS,MVP,MXC,Maneb,NTP,NaHCT,NaLS,NaPCP,Na

led,PCBZ,PCP,PEB,PHTH,PL,PMR,PMT,PPCP,PPHD,PPX,PQT,PRN,PRO,PRT,PSM,RTN,SFR,S

Z,TBC,TBF,TBTO,TCF,TDC,TEG,TFN,TMP,TPTH,TRL,VNT,Zineb,Ziram,ZnS 

 32. McDougald, L. R.; White, R. G., and Hansen, M. F. Efficacy of Naphthalophos and Coumaphos Against 

Nematodes of Goats. POPENV; 1968; 29, (5): 1077-1079. 

Notes: EcoReference No.: 157692 

Chemical of Concern: CMPH 

 33. Miller, R. J.; Li, A. Y.; Tijerina, M.; Davey, R. B., and George, J. E. Differential Response to Diazinon and 

Coumaphos in a Strain of Boophilus microplus (Acari: Ixodidae) Collected in Mexico. BCM,MOR. 

robert.miller@ars.usda.gov//USDA-ARS, Cattle Fever Tick Research Laboratory, 22675 N. 

Moorefield Road, Edinburg, TX 78541////: ENV,MIXTURE; 2008; 45, (5): 905-911. 

Notes: EcoReference No.: 119627 

Chemical of Concern: CMPH,DZ,PPB 

 34. Mutinelli, F.; Baggio, A.; Capolongo, F.; Piro, R.; Prandin, L., and Biasion, L. A Scientific Note on Oxalic 

Acid by Topical Application for the Control of Varroosis. POPENV; 1997; 28, (6): 461-462. 

Notes: EcoReference No.: 151767 

Chemical of Concern: CMPH,OXAC 

 35. Nelson, D. L.; White, R. G.; Mozier, J. O., and Allen, A. D. Toxicity of Larger-than-Recommended Doses of 

Naphthalophos to Cattle, Sheep, and Goats. MOR,PHY,POPENV,MIXTURE,ORAL; 1970; 31, (1): 

199-201. 
111 

Notes: EcoReference No.: 157873 

Chemical of Concern: CMPH,FNTH,TCF 

 36. Neuhauser, H. and Krieger, K. Chemical Control of Varroa jacobsoni in Honey Bees from the AnimalHealth-Industry Aspect. ACC,MOR,POPENV; 1988; 46, 375-379. 

Notes: EcoReference No.: 157770 

Chemical of Concern: CMPH 

 37. O'Neill, D. K. and Hebden, S. P. Investigation of Sheep Dips. Part I - Mixtures of Lime Sulphur and Organic 

Phosphorus Compounds. ACC,MORTOP; 1966; 42, (6): 207-213. 

Notes: EcoReference No.: 104226 

Chemical of Concern: CMPH,CaPS,DZ 

 38. Pettis, J. S.; Collins, A. M.; Wilbanks, R., and Feldlaufer, M. Survival and Function of Queens Reared in 

Beeswax Containing Coumaphos. CEL,GRO,POP,REPENV; 2006; 146, (4): 341-344. 

Notes: EcoReference No.: 157886 

Chemical of Concern: CMPH,FVL 

 39. Pfadt, R. E.; Lloyd, J. E., and Spackman, E. W. Power Dusting with Organophosphorus Insecticides to 

Control the Sheep Ked. POPENV; 1975; 68, (4): 468-470. 

Notes: EcoReference No.: 108644 

Chemical of Concern: CMPH,PSM 

 40. Rammell, C. G. and Bentley, G. R. Decay Rates of Organophosphate Residues in the Fleeces of Sheep 

Dipped for Flystrike Control. ACCTOP; 1989; 32, (2): 213-218. 

Notes: EcoReference No.: 101119 

Chemical of Concern: CMPH,DZ,PTP 

 41. Rammell, C. G.; Bentley, G. R., and Heath, A. C. G. Organophosphate Residues in the Wool of Sheep 

Dipped for Flystrike Control. ACCTOP; 1988; 31, (2): 151-154. 

Notes: EcoReference No.: 101118 

Chemical of Concern: CMPH,DZ,PTP 

 42. Rawlins, S. C. and Mansingh, A. Patterns of Resistance to Various Acaricides in Some Jamaican Populations 

of Boophilus microplus. MORUNK; 1978; 71, 956-960. 

Notes: EcoReference No.: 72313 

Chemical of Concern: 

CBL,CMPH,CPY,DCTP,DDT,DMT,DZ,FNT,HCCH,Naled,PIRM,PPCP,PPHD,PPX 

 43. Samuel, J. J.; Mani, K. B. S.; Cyrus, I., and Natarajan, R. Studies on the Use of Synthetic Atropine 

Substitutes in Organo Phosphorus Pesticide Poisoning. MOR. Dep. Pharmacol.,Madras Vet. 

Coll.,Madras,India////: INJECT,MIXTURE; 1987; 16, (3): 135-136. 

Notes: EcoReference No.: 157693 

Chemical of Concern: CMPH 

 44. Schafer, E. W. Jr.; Brunton, R. B.; Lockyer, N. F., and De Grazio, J. W. Comparative Toxicity of Seventeen 

Pesticides to the Quelea, House Sparrow, and Red-Winged Blackbird. MORORAL,TOP; 1973; 26, 

154-157. 

Notes: EcoReference No.: 38663 

Chemical of Concern: 4AP,CBF,CMPH,DCTP,DEM,EPRN,FNTH,MCB,PRN 

 45. Shaw, R. D.; Cook, M., and Carson, R. E. Jr. Developments in the Resistance Status of the Southern Cattle 

Tick to Organophosphorus and Carbamate Insecticides. MORTOP; 1968; 61, 1590-1594. 

Notes: EcoReference No.: 72637 

Chemical of Concern: 
112 

CBL,CMPH,CPY,DCTP,DZ,EPRN,ETN,HCCH,PPCP,PPHD,PRN,PYN,TXP 

 46. Sun, Y. P. Speed of Action of Insecticides and Its Correlation with Accumulation in Fat and Excretion in 

Milk. MORENV,TOP; 1971; 64, (3): 624-630. 

Notes: EcoReference No.: 114907 

Chemical of Concern: 

ADC,AND,CBL,CHD,CMPH,DDT,DDVP,DEM,DMT,DS,DZ,EN,EPRN,ES,ETN,FNTH,HCCH,H

PT,MLN,MP,MPO,MVP,MXC,Naled,PCTP,PPCP,PPHD,PRN,PRT,PSM,TCF,TVP,TXP 

 47. Suphalucksana, W. and Ching, F. A. A Field Trial on the Efficacy of Ivermectin, Albendazole and 

Coumaphos Against Parasites of Buffalo. POP,REPENV,INJECT,ORAL; 1991; 25, (2): 256-260. 

Notes: EcoReference No.: 157629 

Chemical of Concern: CMPH 

 48. Swierczewska, E.; Niemiec, J., and Noworyta-Glowacka, J. A Note on the Effect of Immunostimulation of 

Laying Hens on the Lysozyme Activity in Egg White. BCM. Department of Poultry 

Breeding,Warsaw Agricultural University,Warsaw,Pol////: INJECT,ORAL; 2003; 21, (1): 63-68. 

Notes: EcoReference No.: 157623 

Chemical of Concern: CMPH