U. S. ENVIRONMENTAL PROTECTION AGENCY

Washington, D.C. 20460 

 OFFICE OF 

PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES 

 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PC Code: 036501 

DP Barcode: 347376

Date: April 28, 2008

MEMORANDUM

Subject: Revised Registration Review Preliminary Problem Formulation for the Ecological 

Risk Assessment of Coumaphos 

To: Richard Dumas, Acting Branch Chief 

Wilhelmena Livingston, Chemical Review Manager 

 Mail Code: 7508P 

 Special Review and Reregistration Division 

 

From: Fred Jenkins, Biologist 

Iwona, Maher, Chemist 

Nancy Andrews, Ph.D., Branch Chief 

Mail Code: 7507P 

 Environmental Risk Branch I 

 Environmental Fate and Effects Division 

 

Attached is EFED’s problem formulation document in support of the coumaphos registration review 

docket opening. This memorandum outlines (1) the methods that will likely be used in the 

ecological risk assessment of coumaphos, (2) data gaps, and (3) additional data needs. 

1
REGISTRATION REVIEW

REGISTRATION REVIEW

ECOLOGICAL RISK ASSESSMENT

PROBLEM FORMULATION FOR:

COUMAPHOS

3-chloro-7-diethoxyphosphinothioyloxy-4-methylcoumarin

PREPARED BY: 

Fred Jenkins, Biologist 

Iwona Maher, Chemist 

Environmental Risk Branch I 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

APPROVED BY: 

Nancy Andrews, Ph.D., Branch Chief 

Environmental Risk Branch I 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

April 28, 2008 

2
1. Problem Formulation 

 

The problem formulation is used to establish the direction and scope of an ecological risk 

assessment. According to the Guidelines for Ecological Risk Assessment (USEPA, 1998), a 

problem formulation consists of defining the problem and purpose for the assessment, and 

developing a plan for analyzing and characterizing risks. The critical components of the problem 

formulation are the selection of the assessment endpoints, the formulation of both the risk 

hypotheses and the conceptual model, and the development of an analysis plan. The analysis plan 

and supporting rationale are aimed at determining whether the coumaphos uses pose an 

unreasonable adverse risk to non-target organisms including those federally listed as threatened or 

endangered (hereafter referred to as “listed”). The registered uses of coumaphos include an 

insecticide/acaricide treatment on livestock and swine bedding for control of flies, mites, and ticks, 

and recently approved IR4 (DP Barcode 315770; Dated: May 16, 2006) for use on bee hives to 

control varroa mites and small hive beetles. 

1.1. Integration of Available Information 

The following coumaphos risk assessment related documents are available in the docket, and will 

serve as the basis for this problem formulation: 

• 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. Dated: July 31, 2006. EPA 738-R-00-10. 

• EFED Drinking Water and Ecological Risk Review for Coumaphos (036501) IR-4 Use on 

Beehives DP Barcode D315770. Dated: 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 Barcode: D303298. Dated: June 6, 2004 

• US EPA Reregistration Eligibility Decision (RED) for Coumaphos. Dated August 1996. 

EPA 738 R-96-014. 

• EFED Review for Coumaphos RED. Dated: Sep. 19, 1994. (EFED’s environmental fate and 

ecological effects sections for the Coumaphos 1996 RED) 

3
1.1.2.1.1 Agency Conclusions Based on Previous Coumaphos Ecological 

Assessments 

The current ecological risk conclusions from the above mentioned coumaphos risk 

assessment documents are as follows: 

Avian Acute Risk 

• Coumaphos is expected to pose a significant 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 pesticide. 

Avian Chronic Risk 

• 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 document’s assessment of acute risk if there were significant 

coumaphos exposure to birds, they would be killed before chronic effects 

could occur. 

Mammalian Acute Risk 

• 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 

a high acute risk to aquatic invertebrates. Coumaphos is not expected to pose 

chronic or acute risks to endangered or non-endangered fish. 

EFED will utilize the information provided by the previous risk assessment documents as a resource 

for conducting the ecological risk assessment for the registration review process. The assessment 

will include risk estimates from two exposure pathways: the application of coumaphos to cattle via 

spray based on registrant submitted data on wash-off estimates from cowhide, and from application 

of bioremediated spent vat-dip solutions to land. Both exposure pathways maybe equally important 

for environmental risks, and are discussed in the screening level aquatic exposure assessment dated 

June 6, 2004 (D303298). 

The indoor use of the coumaphos and the placement of coumaphos-treated strips in beehives to 

avoid contact of bees suggest that there are no complete routes of exposure to surface waters or to 

the surrounding non-target terrestrial environment. Therefore, without evident complete exposure 

4
routes to aquatic and non-target terrestrial organisms, there are no acute or chronic risk concerns 

and no concerns for effects to federally listed threatened or endangered species. 

1.2. Pesticide Type, Class, and Mode of Action 

Coumaphos is an insecticide/acaricide. It belongs to the organophosphate class of pesticides. The 

toxic mode of action of coumaphos is the inhibition of acetyl cholinesterase. 

1.3. Stressor Source and Distribution 

The source of the stressor is considered to be combined residues of the insecticide coumaphos (PC 

Code 036501; O,O-diethyl O-3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl phosphorothioate) 

and its oxygen analog, coumaphoxon (O,O-diethyl O-3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-

yl phosphate) from indoor food and non-food uses. 

1.4. Overview of Pesticide Usage 

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 insects, mites, and ticks on livestock 

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

The predominant use of coumaphos is as an insecticide/acaricide to control insect pest of beef 

cattle. It is also used for the same purposes to treat dairy cattle, horses, sheep, and swine. The 

targeted insect pests include flies (face fly, horn fly), ticks, lice, mites (scabies mite) and screw 

worms. The formulation types of the registered coumaphos products include the technical grade 

active ingredient (96% pure), manufacturing product (25% a.i. dust), end-use products (1% a.i. dust, 

11.6% a.i. and 6.15% a.i. emulsifiable concentrates, and 42% a.i. flowable concentrate). 

Coumaphos is applied directly to the livestock. The equipment used to apply coumaphos includes 

dip vats, low and high-pressure hand wands, back rubber/oiler, mechanical dusters, dust bags and 

shaker cans. Depending on animals treated and formulation type, the maximum label application 

rates range from 0.005 to 0.025 lbs a.i./gallon for spray or dip, 0.076 lbs a.i./gallon of oil for back 

rubbers, 0.000625 to 0.013 lbs a.i./animal for dust, and 0.042 lbs ai/1,000 sq. ft. of swine bedding. 

The coumaphos applications are primarily done during early spring to late summer or during the fly 

season. Multiple applications to livestock and livestock areas are allowed. The use classifications 

for the two liquid products, the 11.6% emulsifiable concentrate and the 42% flowable are as 

Restricted Use Pesticides (RUPs). All other products have general use classifications. For details 

on the maximum application rates, the application equipment, and coumaphos product names refer 

to an attached EFED Label Data Report dated September 13, 2007 (Attachment A: EFED Label 

Data Report 036501EF). 

5
D. Estimated Usage of Pesticide 

This section summarizes the best estimates available for many of the pesticide uses of coumaphos, 

based on pesticide usage information for 1990-1999 available to the Agency. A full listing of all 

uses of coumaphos, with the corresponding use and usage data for each site (cattle or other 

livestock), has been completed and is included in the “Quantitative Usage Analysis for 

Coumaphos,” dated August 15, 2000, which is available in the Public Docket. The data, reported 

on an aggregate and site basis, reflect annual fluctuations in use patterns as well as the variability in 

using data from various information sources. Approximately 71,000 lbs a.i. of coumaphos is used 

annually in the United States. Table 1 provides further detail regarding the annual usage amounts of 

coumaphos in the US. 

Table 1. Coumaphos Estimated Usage for Representative Sites 

Site Lbs. Active Ingredient Applied 

(Likely Average1) 

Percent Livestock Treated 

(Likely Average) 

Cattle 59,000 5.1% 

Other Livestock 12,000 1.3% 

1 

Likely averages are the EPA’s estimates of what the average uses are likely to be sources: U.S. Census of Agriculture; State Usage Surveys 

from TX, KS, NY, WY, and NV; State use recommendations; USDA,NASS, 2000 and EPA data. Refer to the “Quantitative Usage Analysis for 

Coumaphos,” dated August 15, 2000, prepared by OPP Biological and Economic Analysis Division. 

Table 2 provides more recent summary of the estimates available for coumaphos usage in 

California, based on pesticide usage information for 2004-2006 available to the Agency from the 

California Department of Pesticide Regulation. 

Table 2. Coumaphos use in California from 2004 to 2006 

Year Site Lbs AI 

2004 Beehives (all or unspec.) 15.43735 

2004 CHECKMITE+ 47.1 

2004 Honey (sugar crop) 0.0125 

2005 Beehives (all or unspec.) 0.59993 

2006 Beehives (all or unspec.) 3.00378 

By far, the largest use for this insecticide is livestock. This is largely due to the treatment of 

livestock entering the US from Mexico as part of the USDA tick quarantine to prevent Texas cattle 

fever. The national livestock information, provided below, is the most recent available from the 

USDA. While much of the coumaphos use on livestock along the border may be in a dip vat 

application, coumaphos is also used as a body spray, dust, dust bag, pour-on, oiler scratcher, and ear 

tag (USDA/NASS, 2004. Pest Management Strategic Plan for Beef Cattle and Non-lactating Dairy 

Cattle - North Central Region). 

6
 

Table 3. Coumaphos estimated usage on Livestock

Livestock Year Total Applied Application Rate Rate/Head/Year 

 (1,000 lbs) (grams) (grams) 

All Cattle 1999 58.1 2.3 6.9 

 2006 na na na 

Beef 

Cattle 1999 54.8 2.7 7.4 

 2006 na na na 

Dairy 

Cattle 1999 3.3 0.7 3.1 

 2006 2.3 0.2 7.7 

Sheep 2000 0.63 4 5.8 

References: USDA/NASS. 2000. Agricultural Chemical Usage Cattle and Cattle Facilities 

 USDA/NASS. 2007. Agricultural Chemical Usage 2006 Dairy Cattle and Dairy Facilities Summary 

 USDA/NASS. 2001. Agricultural Chemical Usage 2001 Sheep and Sheep Facilities 

1.5. Environmental Fate Summary 

1.5.1 Active Ingredient 

Coumaphos is persistent and moderately mobile to immobile in the soil environment. It may reach 

surface water via runoff and dust drift, and may leach into shallow ground water. The major 

pathway of coumaphos degradation appears to be photodegradation in water (half-life 33 hours). 

Coumaphos is stable to hydrolysis in pH 7, aerobic soil metabolism, and field dissipation. It 

appears to be immobile, with KD values ranging from 61 to 298 for parent, and from 91 to 161 for 

the degradate chlorferon. During one field dissipation study, its mobility appeared to be higher than 

expected from those KD values, which could be attributed to higher concentrations of spent 

coumaphos in soil evaporation pits. 

The major coumaphos degradates identified under aerobic conditions were chlorferon, which 

reached a maximum of 6.2% of the organosoluble radioactivity, and 6-hydroxyl-3-

methylbenzofuran, the oxygen analog, which reached a maximum of 0.2% of radioactivity, both 

recovered at six months. In addition, the oxygen analog, coumaphoxon, was detected in an aqueous 

photodegradation study at a maximum of 10.2% of radioactivity. 

The field dissipation study results support the laboratory finding that coumaphos is persistent. The 

estimated field dissipation half-lives are 118 and 185 days. Soil samples taken 6 to 12 inches deep 

contained coumaphos, however, the soil was not sampled at sufficient depth to define the extent of 

leaching. A special retrospective field dissipation study was conducted to characterize the depth of 

leaching in disposal pits and walkways of coumaphos treatment dip vats. On-site disposal of spent 

coumaphos in unlined pits was found to result in leaching of coumaphos, chlorferon, and 40 potasan 

7
to the subsurface (72 inches in the study), and could result in ground-water contamination in areas 

of shallow ground water. These compounds may reach ground water, although there was 

insufficient depth of soil sampling conducted in the study to determine if coumaphos and/or its 

metabolites could have reached the deep wells that were tested during the study. 

Coumaphos is nearly insoluble in water (0.05 mg/l at 25oC), and its vapor pressure of 1x 10-7 mm 

Hg (20o

C) suggests rather low potential for volatility from soil and water surfaces. Depending on 

pH and concentration the log Kow ranges from 3.85 to 4.04. A supplemental bioaccumulation in 

fish study suggests that total coumaphos accumulated, with a maximum bioconcentration factor of 

541X, in whole bluegill sunfish during 30 days. Accumulated coumaphos residues were depurated 

rapidly, with 98% elimination after 1 day in untreated water. 

1.5.2 Coumaphos Degradate 

The residues of concern are coumaphos and its oxygen analog, coumaphoxon. Coumaphoxon is 

included in the Health Effects Division tolerance expression, and was considered in the drinking 

water assessment. 

Fate and transport data for coumaphoxon are not available. Using a computer estimation program 

(EPI version 3.04), the coumaphoxon Koc value was estimated to be 92.3, and water solubility 31.61 

mg/l at 25o

C. It is based on this information assumed that coumaphoxon is persistent and mobile in 

the soil environment. Subdivision N aerobic soil metabolism and batch equilibrium studies are 

needed for coumaphoxon. These data are needed to confirm the conservativeness of those 

assumptions. 

1.6 Incident Report 

The Agency has received one bird kill that was associated with exposure to coumaphos. The United 

States Fish and Wildlife Service reported that an unknown number of American wigeon were found 

dead in Washington State in 1981. The wigeon were in and around ponds adjacent to a feedlot. 

The report states coumaphos was the causal agent but did not provide information on how the 

chemical was released into the environment. 

In 2003, the Minnesota Department of Agriculture submitted to the Agency a series of eight kills of 

honey bees that occurred in September, 2002. In all of these incidents, analysis of bee tissue or 

pollen, or both, found residues of coumaphos present. While the source of the coumaphos exposure 

was not known, the investigators speculated that the residues probably resulted from the beekeepers 

using Checkmite Bee Hive Pest Control Strips, a coumaphos-containing product that is frequently 

used on bee hives to control Vorroa mites. Investigators identified recent applications of other 

pesticides, including carbaryl and zeta-cypermethrin, in nearby agricultural fields, but no clear 

pattern emerged in the spatial or temporal pattern of these uses that would suggest that they were 

the cause. Furthermore, the residue analysis of bee tissue and pollen did not detect any carbaryl, 

zeta-cypermethrin, or other pesticides. The investigators concluded that insufficient evidence was 

8
available to determine if the exposure to coumaphos played a role in these bee kills or was merely 

incidental. 

The Agency has received no reports of adverse field effects to plants or aquatic organisms that have 

been attributed to the use of coumaphos. The Agency also has received no incident reports from 

pesticide registrants concerning coumaphos contamination of ground or surface water. 

A lack of reported incidents does not necessarily mean that such incidents have not occurred. In 

addition, incident reports for non-target plants and animals typically provide information on 

mortality events only. Reports for other adverse effects, such as reduced growth or impaired 

reproduction, are rarely received (Source: US EPA Coumaphos incident summary statement for 

Registration Review; Dated February 20, 2008; Author: Nicholas Mastrota). 

1.7. Ecological Effects Summary 

Table 4 provides taxonomic groups and test species typically used to indicate the potential for 

ecological effects in screening-level risk assessments. Within each of these very broad taxonomic 

groups, an acute and/or chronic endpoint is selected from the available test data. 

Table 4. Taxonomic Groups and Most Sensitive Test Species Typically for Ecological Effects in 

Screening Level Risk Assessments. 

Taxonomic group Example(s) of representative species Endpoint Used

Birdsa

Bobwhite quail (Colinus virginianus) 

Mallard duck (Anas platyrhynchos) 

Acute, LD50/LC50

Chronic, NOAEC 

Mammals Laboratory rat (Rattus norvegicus) Acute LD50 

NOAEC 

Terrestrial insects Honeybees (Apis mellifera) Acute Oral LD50

Freshwater fishb Rainbow trout (Oncorhynchus mykiss) 

Fathead minnow (Pimephales promelas) 

Acute LC50

Chronic NOAEC 

Freshwater invertebrates Water flea (carinata) 

Water flea (Daphnia magna) 

 

Acute LC50 

 NOAEC 

 

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus) Acute LC50

Estuarine/marine invertebrates Mysid shrimp (Mysidopsis bahia) 

Eastern oyster (Crassostrea virginica) 

Acute LC50

Acute EC50

9
Table 4. Taxonomic Groups and Most Sensitive Test Species Typically for Ecological Effects in 

Screening Level Risk Assessments. 

Taxonomic group Example(s) of representative species Endpoint Used

Terrestrial plants Monocots – N/A 

Dicots – N/A 

Seedling Emergence (Tier 

I or Tier II no EC25

estimated) 

Vegetative Vigor 

(Tier I or Tier II no EC25

estimated) 

Freshwater vascular aquatic 

plants and algae 

Duckweed (Lemna gibba) Acute EC25 

NOAEC 

Freshwater non-vascular 

aquatic plants 

Diatom (Navicula pelliculosa) Acute EC25 

EC05

Estuarine/marine non-vascular 

aquatic plants 

Diatom (Skeletonema costatum) Acute EC50

EC05

a

Birds are used as surrogates for terrestrial phase amphibians and reptiles (US EPA, 2004). b

Freshwater fish are used as surrogates for aquatic phase amphibians (US EPA, 2004). 

1.8. Ecosystems at Risk 

The ecosystems that are predicted to be potentially at risk due to the use and potentially disposal of 

coumaphos include: 1) aquatic habitats in which coumaphos may enter via runoff after a direct 

application of bioremendiated vat-dip solution on land and via wash-off from the cattle hide that 

may wade in these habitats, and 2) terrestrial ecosystems where terrestrial animals may come in 

contact with coumaphos via direct contact with treated cows, exposure to cow hair with coumaphos 

residues, exposure to soil or feed in and around treatment areas, and exposure to soil on which 

bioremendiated vat-dip solution was disposed on. 

1.8.1 Receptors 

The aquatic receptors likely to be exposed to coumaphos include fish, aquatic invertebrates, and 

aquatic stages of amphibians and plants inhabiting water bodies that may contain coumaphos 

washed from treated cattle wading in these habitats. The sole terrestrial receptors likely to be 

exposed to coumaphos are terrestrial animals that may come in contact with coumaphos via direct 

contact with treated cows, exposure to cow hair with coumaphos residues, and exposure to soil or 

feed in and around treatment areas. 

1.8.2. Assessment Endpoints 

Assessment endpoints are defined as “explicit expressions of the actual environmental values that 

are to be protected.” Operationally, the environmental value is represented by an ecological entity 

10
and associated attributes or characteristics. The assessment endpoints for this ecological risk 

assessment will be survival, growth, and reproduction of aquatic organisms and terrestrial animals 

that may be exposed to coumaphos. 

Assessment endpoints and toxicity data used to evaluate the assessment endpoints are identified in 

Tables 4 and 5. 

1.9. Conceptual Model 

The conceptual model depicts the potential ecological risks associated with coumaphos uses. The 

model is generic and assumes that coumaphos can affect terrestrial and aquatic organisms if 

environmental concentrations are sufficiently elevated as a result of coumaphos label uses and 

coumaphos disposal. Coumaphos is an insecticide/acaricide used for external use on animals and 

animal premises applied as a direct whole animal or wound treatment to control pests. It can enter 

the outdoor environment either as excess material lost during outdoor application, as material shed, 

wash off from animals, and during disposal. A diagram of the conceptual model is presented in 

Figure 1. The exposure pathway from disposal of bioremediated vat-dip solution onto land was not 

assessed in 1994 EFED’s RED Chapter. The disposal of coumaphos bioremediated dip-vat solution 

on land maybe equally important for aquatic and terrestrial exposure as coumaphos washoff into the 

water body. 

A review of the label provided revealed the following application restrictions and disposal 

requirements: 

“Do not treat areas such as drinking cups, mangers, or troughs where livestock feed. Do not 

contaminate water, food, feedstuff, food or feed handling equipment, or milk or meat handling 

equipment.” 

“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 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 agricultural land and 

should be disposed according to solid waste disposal regulations established by your Local and/or 

State Environmental Control Agency.” 

The extent of the exposure can be better understood upon availability of current coumaphos 

disposal procedures. There was no mention of the method of disposal for solution contained within 

the bioremediation “evaporation ponds”. Two assumptions can be made with regard to the handling 

of spent solution. Once in the bioremediation ponds, the level of solution within the pond is 

maintained by evaporation and removal and proper disposal of solids. Alternatively, the liquid is 

discharged to water under an NPDES permit or applied to land. Under an NPDES permit, OPP 

assumes that precautions have been taken to adequately protect aquatic life. Because application to 

agricultural land of a pesticide product is generally assessed by OPP, therefore, application of 

bioremediated coumaphos to agricultural land would be assessed as a potential exposure pathway.

11
Roaming cattle with coumaphos treated hides and 

disposal of bioremediated vat-dip solution. 

Stressor 

Source: 

Exposure 

Media 

 

Riparian/Wetland 

Foliage/Soil (via 

runoff and washoff 

from treated cows) 

Surface Water 

Sediment (vat-dip runoff and washoff 

from treated cows) 

Exposure Point Direct Contact 

And Ingestion 

Direct Contact/ 

Root Uptake

Uptake/Adsorption Gill/Integument Uptake 

Receptors Birds (with soil and 

cattle) Terrestrial Upland 

Plants 

Riparian/ 

Wetland 

Plants 

Aquatic Plants Aquatic 

Invert.and 

Vertebrates 

Terrestrial Animal 

•Lethality 

•Reproductive/ 

developmental 

Effects 

•Other adverse 

sublethal effects 

Non-Target Terrestrial or Riparian/Wetland Plants 

•Plant growth abnormalities 

•Lethality 

•Developmental/reproductive 

Effects 

• Reduced Population growth

Aquatic Animals 

•Effects to survival, growth, and 

Reproduction 

•Other adverse sublethal effects 

Altered Terrestrial Community 

Assemblages: 

Reduced food supply and edge habitat 

availability 

Altered Aquatic Community Assemblages: 

Effects to riparian habitat availability 

Effects to food supply 

 Cattle 

 hide 

Upland Soil and 

Foliage (via 

direct 

application from 

diposal of vat 

solution and 

washoff from 

Mammals 

(via 

contact 

with soil 

and 

vegetation 

Direct 

Effects 

Indirect 

Effects 

Figure 1. Conceptual model of the fate/transport and effects of coumaphos in the 

environment. 

1.10. Risk Hypotheses

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

effects resulting from labeled uses or/and disposal of coumaphos. 

1.11. Analysis Plan 

The analysis plan is the final step in the Problem Formulation. During this step measures of 

exposure and measures of effect are used to evaluate the risk hypotheses and are listed in Tables 4 

and 5 for a specific assessment endpoint. The RQ is obtained by dividing the measures of exposure 

12
for a particular assessment endpoint by the measures of effect for that endpoint. 

1.11.1. Measures of Exposure

s exposure to non-target organisms, it is necessary to have information on the 

l of 

dies 

e 

 addition, current guidance, procedure, or protocols on the application of the bioremediated vats 

1.11.2. Measures of Effect 

Registrant Submitted Ecotoxicity

In order to asses

concentration of active ingredient on the hides of treated cattle, and information on the potentia

coumaphos to wash-off into water when cattle wade into bodies of water. The registrant has 

submitted two studies that address these issues (MRIDs: 42512601 and 42512602). Those stu

have been reviewed and found to be acceptable for use in a risk assessment. Information from thos

studies will be incorporated in the registration review risk assessment for both terrestrial and aquatic 

non-target organisms. 

In

dip solution on land are needed. In previous EFED assessment (D303298), a potential exposure 

pathway to bioremediated coumaphos applied to agricultural land was based on guidance from 

proposed USDA land farming methods (D230394; D239676, 6/4/98). At that time, uncertaintie

were associated with the estimated maximum application rate per acre. 

elow is a summary of the ecotoxicity studies submitted by the registrant. 

vian Toxicity

here are nine acceptable avian acute toxicity studies (MRID’s 00022923, 112842, and 00160000) 

urnix 

he avian acute toxicity studies demonstrated that coumaphos’s acute toxicity to birds ranged from 

ased on the Coumaphos 1996 RED document, the Agency concluded that avian reproduction 

 be 

e killed 

he purpose of the field simulation study was to evaluate the exposure of wild birds to coumaphos 

B

A

T

and one supplemental simulated field study (Gdln. 71-5; MRID 425126-04). The species tested in 

the avian acute toxicity studies include Mallard duck (Anas platyrhynchos), Bobwhite quail 

(Colinus virginianus), Ring-necked pheasant (Phasianus colchicus), and Japanese quail (Cot

japonica). There were 34 species of wild birds tested in the simulated field study. 

T

highly to very highly toxic on an acute oral toxicity basis (acute oral LD50 toxicity values ranged 

from 7.94 ppm - 29.8 ppm), and moderately to very highly toxic on an acute dietary toxicity basis

(acute dietary toxicity values ranged from 85 ppm - 401 ppm). 

B

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

exposed to a pesticide repeatedly or continuously. According to the 1996 RED document’s 

assessment of acute risk if there were significant coumaphos exposure to birds, they would b

before chronic effects could occur. Currently, there are no available reproductive toxicity studies. 

T

13
treated cows in an open pen. The field simulation study was deemed as scientifically sound but did 

not meet the requirements for a simulated (pen) field test. The study was classified as 

supplemental, because only one study site was used and only 8 cows were treated. The

indicate that potential pathways of exposure to birds include direct contact with treated cows, 

exposure to cow hair, and exposure to soil or feed in and around treatment areas. 

 results 

ammalian Toxicity 

he registrant submitted mammalian ecotoxicity studies testing coumaphos include a rat acute oral 

he rat acute LD50 study demonstrated that coumaphos is highly toxic to mammals (LD50 value of 

(RBC) 

 47 

sect toxicity 

ccording to the 1996 RED document for coumaphos, the Agency deemed that the data 

rns, and no 

ish Toxicity 

reshwater fish acute toxicity 

here are nine acceptable registrant submitted freshwater fish acute toxicity studies testing 

e trout 

m v.). 

ased on the results of these studies coumaphos was classified as moderately toxic to highly toxic 

M

T

LD50 study (MRID 00110597) and a rat two-year generational reproduction study (MRID 

43061701). 

T

17 mg/kg). The rat two-year generation reproduction study demonstrated that cholinesterase 

inhibition, observed at 5 and 25 ppm was manifested as dose-related decreases in erythrocyte 

and plasma cholinesterase (ChE). The RBC ChE was inhibited 31-70%, relative to concurrent 

controls, at 5 ppm and 53%-95% at 25 ppm. Generally, no differences were noted between Day

(or 56) and Day 91 ChE levels. Brain levels were biologically 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 NOEL and LEL for ChE

inhibition were 1 and 5 ppm, respectively. There were no other signs of systemic toxicity. The 

NOEL and LEL for systemic toxicity was equal to or greater than 25 ppm. Reproductive toxicity

was not observed in this study. Consequently, the NOEL for reproductive toxicity was 25 ppm and

the LEL for reproductive toxicity was greater than 25 ppm.

 

In

A

requirements for non-target insects testing are not applicable for the coumaphos use patte

studies were required or submitted. 

F

F

T

coumaphos, TGAI, (MRID’s 40098001, and 112840). The species tested include 

Cutthroat trout (Oncorhynchus clarki), Rainbow trout (Oncorhynchus mykiss), Lak

(Salvelinus namaycush), Channel catfish (Ictalurus punctatus), Bluegill sunfish (Lepomis 

macrochirus), Largemouth bass (Micropterus salmoides), and Walleye (Stizostedion vitreu

B

to freshwater fish (LC50’s range from 0.340 ppm to 5.9 ppm). 

14
Freshwater fish chronic toxicity 

here is one available freshwater fish early-life stage study using rainbow trout (Oncorhynchus 

arine estuarine fish acute toxicity 

here is one registrant submitted marine estuarine fish acute toxicity test (MRID 40228401) using 

arine/ estuarine fish chronic toxicity

urrently, no data have been submitted to the Agency on the chronic effects of coumaphos to 

quatic Invertebrate Toxicity

reshwater invertebrate acute toxicity 

here are six registrant submitted freshwater invertebrate acute toxicity studies testing coumaphos 

 

reshwater invertebrate chronic toxicity 

ere is one registrant submitted freshwater invertebrate chronic toxicity study (MRID 431166-01). 

arine/estuarine invertebrate acute toxicity 

here are two registrant submitted marine/estuarine invertebrate acute toxicity studies testing 

trea 

tern 

T

mykiss). The results of this study demonstrated that chronically exposing the early life-stage of 

rainbow trout caused significant effects to growth at a NOEC, and a LOEC of 0.0117 ppm, and 

0.0246 ppm, respectively (MRID 43066301). 

M

T

sheepshead minnow (Cyprinodon variegates). Based on the results of this study, coumaphos is 

classified as highly toxic to marine/estuarine fish (LC50 = 0.280 ppm). 

M

C

marine/estuarine fish. 

A

F

T

(MRID’s 40098001, 05009242, 05017538, 41778503, and 41778504). These studies test species of

water flea and scud including Daphnia magna, Simocephalus serrulatus, and Gammarus lacustris. 

Based on the Agency’s review of the studies, three of these studies were deemed acceptable and 

three were deemed supplemental. The results of these studies showed that coumaphos is very 

highly toxic to freshwater invertebrates (EC50’s range from 0.000074 ppm to 0.000224 ppm). 

F

 

Th

This study is a Daphnia magna chronic toxicity study (Gdln 72-4). Based upon the Agency’s 

review of the study, the study was deemed as acceptable. This test shows survival as the most 

sensitive endpoint. The NOEAC for survival is 0.000037 ppm. 

M

T

comaphos’s acute toxicity to the pink shrimp (Penaeus duorarum) and eastern oyster (Crassos

virginica). Based on the Agency’s review of these studies, both are deemed as acceptable. The 

results of these studies indicate that coumaphos is highly toxic to very highly toxic to marine 

estuarine invertebrates (EC50 values are 0.002 ppm and 0.290 ppm for the pink shrimp and eas

oyster respectively). 

15
Marine/estuarine invertebrate chronic toxicity

urrently, there are no marine/estuarine invertebrate chronic toxicity study data available to the 

on-target Plant Toxicity 

urrently no non-target plant toxicity data have been submitted to the Agency. 

ata requirements for 

e 

ntial 

et 

1.11.2.1 Most Sensitive Endpoints of Effects Data 

The following tables 5 and 6 demonstrate the most sensitive endpoints of all the registrant submitted 

ailable 

C

Agency. 

N

C

Based on the 1996 RED document for coumaphos, the Agency concluded that d

non-target plant testing are not applicable for the coumaphos use patterns, and no studies were 

required. However the Agency has currently concluded in this problem formulation that becaus

cattle with coumaphos treated hides may wade in aquatic water bodies, the aquatic plants in these 

water bodies may be exposed to coumaphos that washes off the hides of these wading cattle. 

Aquatic plant toxicity data is needed to evaluate the potential effects that aquatic plants may 

experience upon being exposed to coumaphos. The Agency also presumes that there is a pote

that terrestrial plants will be exposed to coumaphos via the disposal of the dip vat solution. As 

mentioned in the Conceptual Model section more information is needed about the method of 

disposal of the vat dip solution in order to adequately access the potential exposure to non-targ

organisms such as terrestrial plants. 

terrestrial toxicity studies and aquatic organism toxicity studies respectively. These endpoints will 

be the proposed measures of effects that will be used to calculate risk quotients for the registration 

review screening level risk assessment of coumaphos. The proposed measures of effects are 

however subject to change based on the results of the Agency’s review of coumaphos data av

in the open literature via the ECOTOX database. 

 

Table 5. Summary of terrestrial assessment endpoints and proposed measures 

of effects for the screening level risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint 

Avia Acute oral LD50 n Acute Effects to Survival = 29.8 mg/kg (MRID 00160000) 

Acute dietary LC50 = 85 ppm (MRID 112842) 

A No data available * vian Chronic Effects to 

Reproduction, Survival, and/or 

Growth 

Mammalian Acute Effects to 

Acute oral LD50 17 mg/kg (MRID 00110597) 

Survival 

Mammalian Chronic Effects to NOEAL = 1 ppm (MRID 43061701) 

Reproduction, Survival, and/or 

16
Table 5. Summary of terrestrial assessment endpoints and proposed measures 

of effects for the screening level risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint 

Growth 

Non-target Beneficial Insect Acute No data available ** 

Effects to Survival 

errestrial Plants Survival and 

No data available *** 

T

Growth 

* d on the Coumaphos 1996 RED document, the Agency concluded that avian reproduction studies 

nificant 

* Note: According to the 1996 RED document for coumaphos, the Agency deemed that the data requirements 

l 

** Note: Currently no non-target plant toxicity data have been submitted to the Agency. 

ents for non-target 

Note: Base

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

pesticide repeatedly or continuously. The assessment of acute risk (§A.2.b) indicates that if there were sig

exposure to birds, they would be killed before chronic effects can occur. 

*

for non-target insects testing are not applicable for the coumaphos use patterns, and no studies were required or 

submitted. However, because of the recently approved IR4 registration to use coumaphos in honey bee hives to 

control varroa mites and small hive beetles, the Agency will need this data to evaluate the potential toxic effects 

of coumaphos to honey bees. This data is needed especially since coumaphos’s targeted mode of action is to 

control insect pests. In addition, according to the Agency’s incident report for coumaphos, there was a bee kil

incident in which an analysis revealed that the bee’s tissue and pollen in this incident contained residues of 

coumaphos. Consequently, the Agency needs to determine whether the toxic mode of action will adversely 

affect bees. 

*

Based on the 1996 RED document for coumaphos, the Agency concluded that data requirem

plant testing are not applicable for the coumaphos use patterns, and no studies were required. 

Table 6. Summary of aquatic assessment endpoints and proposed measures of effects 

for the screening level risk assessment of Coumaphos. 

Assessment Endpoint Measurement Endpoint

reshwater Fish Acute Effects to LC50 = 280 ppb (MRID 40098001) F

Survival 

Freshwater Fish Chronic Effects to NOEAL = 11.7 ppb (MRID 43066301) 

Reproduction, Survival, and/or 

Growth 

Freshwater Invertebrate Acute LC50 = 0.074 ppb (MRID 40098001) 

Effects to Survival 

reshwater Invertebrate Chronic OEAL = 0.0337 ppb (MRID 431166-01) F

Effects to Reproduction, Survival, 

N

17
Table 6. Summary of aquatic assessment endpoints and proposed measures of effects 

for the screening level risk assessment of Coumaphos. 

Assessment Endpoint Measurement Endpoint

and/or Growth 

Marine/Estuarine Fish Acute LC50 = 280 ppb (MRID 40228401) 

Effects to Survival 

Marine/Estuarine Fish 

rvival 

No data available 

Reproduction and/or Su

Marine/Estuarine Invertebrate LC50 = 2 ppb (MRID 40228401) 

Survival 

Marine/Estuarine Invertebrate No data available 

Reproduction and/or Survival 

Aquatic Vascular and Non-vascular No data available * 

Plant Survival and Growth 

* Note: Currently no non-target plant toxicity data have been submitted to the Agency. 

irements for non-target plant 

atic 

1.11.3. Preliminary Identification of Data Gaps for Fate and Ecological Assessment 

nvironmental fate and transport data for coumaphos are mostly supplemental; however, support a 

tter 

Based on the 1996 RED document for coumaphos, the Agency concluded that data requ

testing are not applicable for the coumaphos use patterns, and no studies were required. However the Agency has 

currently concluded in this problem formulation that because cattle with coumaphos treated hides may wade in aqu

water bodies, the aquatic plants in these water bodies will be exposed to coumaphos that washes off the hides of these 

wading cattle. Aquatic plant toxicity data is needed to evaluate the potential effects that aquatic plants may experience

upon being exposed to coumaphos. 

E

qualitative characterization of the properties of coumaphos in the environment. The only missing 

laboratory studies are anaerobic soil metabolism study (162-2), aerobic and anaerobic aquatic 

metabolism studies (162-3, 162-4). The missing laboratory studies would be beneficial for a be

characterization of the potential for coumaphos leaching to ground water or remaining in surface 

water at concentrations of ecological or human health concern; however they will not adversely 

effect the risk conclusions as presented in the 2004 Screening Level Aquatic Exposure Assessment 

for the Use of Coumaphos in the Pacific Northwest and California, nor in the 1996 RED. 

18
In addition, there are no environmental fate data for the coumaphoxon. Coumaphoxon, oxygen 

% 

able 7, below, identifies fate and ecological studies, which are missing or are not acceptable, and 

analog of coumaphos, was detected in an aqueous photodegradation study at a maximum of 10.2

of applied radioactivity. Coumaphoxon is coumaphos’ degradate of concern due to its toxicity 

being greater than the toxicity of parent. Therefore, Subdivision N aerobic soil metabolism and

batch equilibrium studies are proposed to be requested for coumaphoxon. 

T

may be requested to assess risk to the environment. Coumaphos is an insecticide/acaricide used for

external use on animals and animal premises applied as a direct whole animal or wound treatment to 

control pests. It can enter the outdoor environment either as excess material lost during outdoor 

application, as material shed, washoff from animals, and during disposal. The extent of exposure

from bioremediated spent vat-dip solution can be better understood upon availability of current 

coumaphos disposal procedure/techniques. If proven that these routes of expose are minimal or 

none, the fate studies for coumaphoxon would be waived. 

Table 7. Preliminary Identification of Data Gaps for Fate and Ecological Assessment. 

Fate and Ecological 

Taxa studies 

Description of 

studies 

Projected status of Basis for decision 

data gaps 

Aquatic plant toxicity dy was uest the study Refer to information provided below 

studies for guideline 

850.4400 and 850.5400 

Parent – Stu

not submitted 

Proposed to req

Anaerobic soil metabolism Study not requested 

study 

Parent - Study was

not submitted 

Aerobic aquatic metabolism 

study 

Parent - Study was 

not submitted 

Study not requested 

Anaerobic aquatic 

metabolism study 

Parent - Study was 

not submitted 

Study not requested 

Registrant requested 

Waiver was granted under the 

condition that disposed spent 

vat-dip on land will not 

exceed concentration of 0.01 

ppm in the top 6” soil. 

a waiver. 

It will characterize the potential for coumaphos 

leaching to ground water or remaining in surface

water. If current disposal protocol fulfills the 

waiver requirement the study is not needed. 

Aerobic soil metabolism Oxon analog - Study To confirm the computer estimated (EPI v. 3.04) 

study was not submitted 

Proposed to request the study 

DW modeling parameter. 

Batch equilibrium study Oxon analog - Study 

was not submitted 

Proposed to request the study To confirm the computer estimated (EPI v. 3.04) 

DW modeling parameter. 

Fate Data Gaps 

Guideline Number: 835.4100 

Study Title: Aerobic Soil Metabolism (Oxygen Analog) 

Guideline Number: 835.1220 

Study Title: Batch Equilibrium (Oxygen Analog) 

Rationale for Requiring the Environmental Fate Studies Performed in the Laboratory 

Depend

m 

ing on how quickly and to what extent coumaphoxon degrades in soil, and to what extent it is

mobile; coumaphoxon may or may not contribute to ground water and surface water contamination fro

cattle washoff and/or disposal of bioremediated spent vat-dip onto land. 

19
EPA requires a series of individual laboratory studies as well as field studies to assess the behavior and fate 

f a pesticide in the environment. Controlled environmental fate and transport laboratory studies are used to 

ta 

formation on 

ines the persistence of the pesticide, in this case its oxygen 

nalog, when it interacts with soil microorganisms under aerobic conditions. These studies also identify the 

ticide or degradate in soil, the potential to 

ach into the shallow groundwater or its availability to surface runoff following rainfall events. 

o

determine the persistence, mobility, and bioconcentration potential of a pesticide active ingredient and its 

major degradates. Coumaphoxon, coumaphos’ oxygen analog, is a degradate of concern, and therefore one 

metabolism study and one mobility study are requested to provide the minimum information on fate and 

transport of this degradate. The studies offer information on how, or by what mechanism, the pesticide 

degrades, the rate at which it degradates, where it goes, and what transformation products are formed. Da

from these studies are used as inputs to exposure models. These models estimate the expected 

environmental concentrations of the pesticide and the pesticide’s degradates under various environmental 

and use conditions. The laboratory studies also help to focus field study design by providing in

which transformation products are likely to be produced, and thus need to be tracked, and the 

environmental media (e.g., soil, sediment, water, air) that should be sampled, including the depth to which 

soil/sediment samples should be collected. 

The soil microbial metabolism study determ

a

significant degradates that result from biological degradation. 

The batch equilibrium study determines the mobility of the pes

le

Practical Utility of the Data 

How will the data be used? 

studies would facilitate a better understanding of coumaphos’ oxygen analog 

degradation under aerobic (oxygen-rich) conditions in the laboratory, and as an input parameter for 

 etter understanding of coumaphos’ oxygen 

analog mobility in soil in the laboratory, and as an input parameter for drinking water modeling and 

 studies help to determine how fast the oxygen analog (coumaphoxon) 

degrades in the presence of microorganisms in different natural soils. They also determine what 

How could the data change the Agency’s decision, or impact the Agency’s future decision-making? 

 data indicate that coumaphoxon degrades slowly in soil, and is mobile, then coumaphos usage on cattle 

 The soil metabolism 

drinking water modeling and aquatic modeling. 

The batch equilibrium study would facilitate a b

aquatic modeling. 

The soil metabolism

metabolites are formed. 

If

and/or disposal of bioremediated cattle dip solution may pose risk to aquatic organisms, and additional 

use/disposal precautions and/or restrictions may be necessary. 

Ecological Toxicity Data Gaps 

Guideline Number: 850.4400 (Aquatic Plant Toxicity Test, Tier 1) 

Guideline Number: 850.5400 (Study Title: Algal Toxicity, Tier I) 

Rationale for Requiring the Aquatic Plant and Algal Toxicity Studies

Cattle often wade in aquatic water bodies that are located in and around their pastures. Thus, if cattle with 

coumaphos treat of these 

t or 

ed hides wade in these water bodies, the aquatic plant and algal inhabitants 

ecosystems may be exposed to coumaphos that washes off the hides of these cattle. Currently, there are no 

aquatic plant or algal toxicity data testing coumaphos that have either been submitted by the registran

are available in the open literature. Thus, in accordance with the 40 Code of Federal Regulations Part 158 

aquatic plant and algal toxicity data for coumaphos are required. In addition based on the Agency’s 

20
TOXDATA database, very little data are available which evaluate the toxic effects of other 

organophosphate pesticides on aquatic plants and algae. Consequently, the Agency is very uncertain

effects that coumaphos may have on aquatic plants and algae. However, based on available 

organophosphate aquatic plant and algal toxicity data, naled, an organophosphate insecticide such as 

coumaphos, demonstrates significant acute toxicity to algae and aquatic plants at EC50 values

ppb (MRID 42529603). Moreover according to an assessment ("Coumaphos Analysis of Risks to 

Endangered and Threatened Salmon and Steelhead", August 1, 2004 by Jennifer Leyhe) presenting a crude 

estimation of level of exposure from loss of coumaphos applied to cattle wading into surface water,

estimated environmental concentration (EEC) from one cow was estimated at 0.15 ppb, assuming 50% was 

wash-off. Thus assuming that 100 cows would wade in the same water, the EEC would be 15 ppb. This

level of exposure is within the range at which naled caused significant acute toxic effects to aquatic plants 

and algae. Therefore, in order to address the uncertainty regarding the toxic effects of coumaphos to 

aquatic plants and algae, the Agency must obtain aquatic plant and algal toxicity data. This is especially 

important considering that 1) aquatic plants and algae may potentially be exposed to coumaphos 

concentrations that are within the range of naled concentrations that cause significant aquatic plant and 

algal toxicity, 2) coumaphos may possibly have similar aquatic plant and algal toxicity to naled b

two chemicals are in the same chemical class, and 3) aquatic plants and algae are a critical element of 

healthy aquatic ecosystem, and thus it is very important to evaluate the potential impact that coumaphos 

may have on them. 

 of the 

 as low as 12 

 the 

ecause the 

How did the Agency make their decision without the data? 

 initially presumed that the registered uses 

ould result in minimal coumaphos exposure to plants. Consequently, the Agency concluded that no plant 

t 

e 

uatic 

to calculate risk quotient calculations that will determine whether or not 

quatic plants or algae exposed to the estimated environmental concentrations of coumaphos are at risk 

o 

or impact the Agency’s future decision-making? 

vel of concern, the Agency may make a decision to mitigate the usage of coumaphos to alleviate the risks 

According to the Coumaphos 2006 RED document, the Agency

w

or algal toxicity data were required for coumaphos. The Agency also presumed in the 2006 RED documen

that the primary non-target organisms that would be exposed to coumaphos would include 1) aquatic 

invertebrates and fish inhabiting water bodies that may encounter wading cattle with coumaphos treated 

hides and 2) birds that may be exposed to coumaphos via direct contact with the hides of coumaphos 

treated cattle. However, based upon the Agency’s current review of the registered uses of coumaphos, th

Agency has determined that coumaphos treated cattle that wade in aquatic habitat will also result in aq

plant and algal exposure to coumaphos. 

How will the data be used? 

The Agency will use the data 

a

above the Agency’s level of concern. If the risk quotient calculations from this data demonstrate risk t

aquatic plants or algae that exceed the Agency’s level of concern, this data may also be used to help the 

Agency to determine a means of mitigating this risk. 

How could the data change the Agency’s decision, 

If the data reveals that coumaphos poses adverse risks to aquatic plants or algae that exceed the Agency’s 

le

posed to aquatic plants or algae. 

21
1.11.3.1 Other Informational Needs 

There i infor ency in refining the ecological risk assessment, 

including any species-specific effects determinations. The Agency is very much interested in 

ning to disposal of bioremediated cattle dip spent solution (i.e. 

dried sludge generated in the evaporation ponds) 

 and equipment 

lication rates 

 intervals, and maximum number of applications 

3. on (e.g., acreage and geographical distribution of relevant 

 and 90 percentile reported use rates (lbs. a.i./acre) from usage data – national, state, 

unty 

tion for non-agricultural uses (e.g., forestry, residential, rights-of-way) 

sage data (not derived from state level data) 

 area 

 was applied in the county/sub-county area 

n-target plant damage and avian, fish, reptilian, amphibian and 

lready reported to the Agency 

The analysis plan will be revisited and potentially revised depending upon the data available in the 

pen literature and the information submitted by the public in response to the opening of the 

 1.12. Open Literature 

s specific mation that will assist the Ag

obtaining the following information: 

1. any current information pertai

2. confirmation on the following label information 

a. sites of application 

b. formulations 

c. application methods

d. maximum app

e. frequency of application, application

per season 

f. geographic limitations on use 

use or potential use distributi

crops) 

4. use history 

5. median th

and county 

6. application timing (date of first application and application intervals) by crop – national, 

state, and co

7. sub-county crop location data 

8. usage/use informa

9. directly acquired county-level u

a. maximum reported use rate (lbs. a.i./acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county

e. the year the pesticide was last used in the county/sub-county

f. the years in which the pesticide

10. typical interval (days) 

11. state or local use restrictions 

12. ecological incidents (no

mammalian mortalities) not a

13. monitoring data 

o

Registration Review docket. 

22
23

 have been found that might provide useful information in the areas of 

previously discussed data gaps. 

Agency uses the ECOTOX database as its mechanism for 

arching the open literature for ecological effects information. ECOTOX integrates three 

 which 

ife, 

ore 

ently, 

.13. Residues of Coumaphos and Coumaphos Degradates in Water 

ubmitted fate and transport data suggest that coumaphos is persistent and moderately mobile to 

mobile. If applied to soil coumaphos may potentially drift off or runoff into surface water, and 

ed 

 be applied directly to soils where it 

ould be available for leaching into ground water, or for direct runoff following a runoff producing 

stimate of the potential coumaphos and coumaphoxon 

nvironmental exposures from the disposal of bioremediated vat-dip solution for an FQPA 

of 

s 

ter concerns exist for coumaphos used in beehives within the honeybee colony in 

ccordance with the coumaphos product label. The use of coumaphos impregnated strips, 

No open literature fate studies

In regards to ecotoxicity data, the 

se

previously independent databases - AQUIRE, PHYTOTOX, and TERRETOX - into a system

includes toxicity data derived predominately from the peer-reviewed literature, for aquatic l

terrestrial plants, and terrestrial wildlife, respectively. Endpoints from ECOTOX are used to 

calculate risk quotients for non-target organisms only if these endpoints are acceptable and are m

sensitive than the most sensitive endpoints produced by the registrant submitted studies. Curr

the Agency’s ECOTOX database search for coumaphos open literature data is pending completion. 

1

S

im

leach into shallow ground water. Although, no data were submitted for coumaphoxon, it is assum

that this degradate of coumaphos is also persistent and mobile, thus, may potentially runoff into 

surface water and leach into ground water resources. In shallow clear waters with good light 

penetration, coumaphos will rapidly form coumaphoxon. 

Coumaphos waste product, after being bioremediated, could

w

rainfall event. In addition, there is a potential environmental exposure from spray applications to

cattle that subsequently wade into surface water where material is washed off from direct contact 

with water, and during rain events. 

On June 6, 2000 EFED provided an e

e

assessment (DP266513). At that time, the exposure pathway associated with the application 

coumaphos to cattle via spray, that may be equally as important for drinking water assessment, wa

not assessed. 

No drinking wa

a

CheckMite+® Pest Control Strip, within a beehive structure effectively eliminates pathways of 

exposure to surface and ground water.