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 Fo rmulation for the Ecological Risk Assessment of Coumaphos

To: Richard Dumas, Acting Branch Chief Wilhelmena Livingston, Chemical Review Manager Mail Code: 7508P Special Review and Re registration 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 couma phos 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.

1R EGISTRATION R EVIEW



## R EGISTRATION 

## R EVIEW



## E COLOGICAL 

## R ISK 

## A SSESSMENT



## P ROBLEM 

## F ORMULATION FOR 

## :



# C OUMAPHOS

3-chloro-7-diethoxyphosphinothioyloxy-4-methylcoumarin

P REPARED B Y :

Fred Jenkins, Biologist Iwona Maher, Chemist Environmental Risk Branch I Environmental Fate and Effects Division Office of Pesticide Programs

A PPROVED B Y :

Nancy Andrews, Ph.D., Branch Chief Environmental Risk Branch I Environmental Fate and Effects Division Office of Pesticide Programs

April 28, 2008

21 . Problem Formulation

The problem formulation is used to establish the direction and scope of an ecological risk assessment. According to the Guidelines fo r Ecological Risk Assessment (USEPA, 1998), a problem formulation consists of defining the problem and purpose for the assessment, and developing a plan for analyzing a nd characterizing risks. The cri tical 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 developm ent of an analysis plan. The analysis plan and supporting rationale are aimed at determ ining whether the coumaphos uses pose an unreasonable adverse risk to non-target organisms in cluding those federally list ed 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; Da ted: 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 th is problem formulation:

• Finalization of Interim Reregistration Eligibili ty Decisions (IREDs) and Interim Tolerance Reassessment and Risk Management Deci sions (TREDs) for the Organophosphate Pesticides, and Completion of the Tolerance Reassessment and Reregistration Eligibility Process for the Organophosphate Pesticid es. Dated: July 31, 2006. EPA 738-R-00-10.

• EFED Drinking Water and Ecological Risk Re view 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 Deci sion (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)

31.1.2.1.1 Agency Conclusions Based on Previous Coumaphos Ecological Assessments

The current ecological risk conclusions fr om the above mentioned coumaphos risk assessment documents are as follows:

Avian Acute Risk

• Coumaphos is expected to pose a signific ant acute risk to birds. Birds may be subject to primary exposure via inge stion 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 repr oduction studies were not required for coumaphos. Such studies may be required wh en birds are likely to be exposed to a pesticide repeatedly or continuously. Acco rding to the 1996 RED document’s assessment of acute risk if there were significant coumaphos exposure to birds, they woul d 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 expect ed 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 e ndangered or non-endangered fish.

EFED will utilize the information provided by the pr evious 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 pathwa ys: 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 th e screening level aquatic exposure assessment dated June 6, 2004 (D303298).

The indoor use of the coumaphos a nd the placement of coumaphos-tre ated 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, w ithout evident complete exposure

4routes 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/acaric ide. It belongs to the organophos phate class of pesticides. The toxic mode of action of coumaphos is th e inhibition of acetyl cholinesterase.

1.3. Stressor Source and Distribution

The source of the stressor is considered to be co mbined 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 St ates in 1958 for use as an insecticide. A dust formulation, the first end-use produc t, was registered the following y ear for the control of insects on cattle. Currently, coumaphos is registered for the control of insects, mite s, 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 insec ticide/acaricide to contro l 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 f lies (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), manuf acturing product (25% a.i. dust), end-use products (1% a.i. dust, 11.6% a.i. and 6.15% a.i. emulsifiable concentr ates, and 42% a.i. flowable concentrate). Coumaphos is applied directly to the livestock. The equipment us ed 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 spra y 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 duri ng early spring to late summer or during the fly season. Multiple applications to livestock and livestock areas are al lowed. The use classifications for the two liquid products, the 11.6% emulsifiab le 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 applicati on equipment, and coumaphos product names refer to an attached EFED Label Data Report date d September 13, 2007 (Attachment A: EFED Label Data Report 036501EF).

5D. 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 av ailable to the Agency. A full listing of all uses of coumaphos, with the corresponding use a nd usage data for each site (cattle or other livestock), has been completed and is include d in the “Quantitative Usage Analysis for Coumaphos,” dated August 15, 2000, which is availa ble in the Public Dock et. The data, reported on an aggregate and site basis, reflect annual fluctuat ions in use patterns as well as the variability in using data from various information sources. Ap proximately 71,000 lbs a.i. of coumaphos is used annually in the United States. Ta ble 1 provides further detail rega rding the annual usage amounts of coumaphos in the US.

Table 1. Coumaphos Estimated Usage for Representative Sites

Site Lbs. Active Ingredient Applied (Likely Average 1 ) 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 wh at the average uses are likely to be sources : U.S. Census of Agriculture; St ate Usage Surveys from TX, KS, NY, WY, and NV; State use recommendations; USDA,NA SS, 2000 and EPA data. Refer to the “Quantitative Usage Analysis for Coumaphos,” dated August 15, 2000, prepared by OP P 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 liv estock. 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 liv estock along the border may be in a dip vat application, coumaphos is also used as a body spra y, 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).

6Table 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. Agricultura l Chemical Usage Cattle and Cattle Facilities USDA/NASS. 2007. Agri cultural Chemical Usage 2006 Dairy Cattle and Dairy Facilities Summary

USDA/NASS. 2001. Agricultural Chemical Usag e 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 wate r (half-life 33 hours). Coumaphos is stable to hydrolys is in pH 7, aerobic soil metabolism, and field dissipation. It appears to be immobile, with K D values ranging from 61 to 298 for parent, and from 91 to 161 for the degradate chlorferon. During one field dissipa tion study, its mobility appeared to be higher than expected from those K D values, which could be attributed to higher concentrations of spent coumaphos in soil evaporation pits.

The major coumaphos degradates identified und er aerobic conditions were chlorferon, which reached a maximum of 6.2% of the orga nosoluble radioactivity, and 6-hydroxyl-3- methylbenzofuran, the oxygen analog, which reac hed a maximum of 0.2% of radioactivity, both recovered at six months. In addition, the oxyge n analog, coumaphoxon, was detected in an aqueous photodegradation study at a maximu m 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 sample d at sufficient depth to define the extent of leaching. A special retrospective field dissipatio n study was conducted to ch aracterize the depth of leaching in disposal pits and walkways of couma phos treatment dip vats. On -site disposal of spent coumaphos in unlined pits was found to result in leaching of coumaphos, chlorferon, and 40 potasan

7to the subsurface (72 inches in the study), and co uld 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 we lls that were tested during the study.

Coumaphos is nearly insoluble in water (0.05 mg/l at 25 o C), and its vapor pressure of 1x 10 -7 mm Hg (20 o C) suggests rather low potentia l for volatility from soil a nd water surfaces. Depending on pH and concentration the log K ow ranges from 3.85 to 4.04. A supplemental bioaccumulation in fish study suggests that total coumaphos accumulate d, with a maximum bioconcentration factor of 541X, in whole bluegill sunfish during 30 days. Accumulated coumaphos re sidues were depurated rapidly, with 98% elimination af ter 1 day in unt reated 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 toleran ce expression, and was cons idered in the drinking
water assessment.

Fate and transport data for coumaphoxon are not av ailable. Using a com puter estimation program (EPI version 3.04), the coumaphoxon K oc value was estimated to be 92.3, and water solubility 31.61 mg/l at 25 o C. It is based on this information assumed that coumaphoxon is persistent and mobile in the soil environment. Subdivi sion 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 a ssociated with exposure to coumaphos. The United States Fish and Wildlife Servi ce 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 agen t but did not provide information on how the chemical was released into the environment.

In 2003, the Minnesota Department of Agriculture subm itted 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 th e residues probably resulted from the beekeepers using Checkmite Bee Hive Pest Control Strips, a coumaphos-containing produc t that is frequently used on bee hives to control Vorroa mites. Inve stigators identified recent applications of other pesticides, including carbaryl a nd zeta-cypermethrin, in nearby agricultural fields, but no clear pattern emerged in the spatial or temporal pattern of th ese uses that would s uggest 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 inves tigators concluded that insufficient evidence was

8available 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 Ag ency 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 specie s typically used to in dicate the potential for ecological effects in screening-le vel risk assessments. Within each of these very broad taxonomic groups, an acute and/or chroni c endpoint is selected from the available test data.

Table 4. Taxonomic Groups and Most Sensitive Te st Species Typically for Ecological Effects in Screening Level Risk Assessments.

Taxonomic group Example(s) of representative species Endpoint Used

Birds a Bobwhite quail ( Colinus virginianus ) Mallard duck ( Anas platyrhynchos ) Acute, LD 50 /LC 50 Chronic, NOAEC

Mammals Laboratory rat ( Rattus norvegicus ) Acute LD 50 NOAEC

Terrestrial insects Honeybees ( Apis mellifera ) Acute Oral LD 50

Freshwater fish b Rainbow trout ( Oncorhynchus mykiss )

Fathead minnow ( Pimephales promelas ) Acute LC 50

Chronic NOAEC

Freshwater invertebrates Water flea ( carinata )

Water flea ( Daphnia magna ) Acute LC 50

NOAEC

Estuarine/marine fish Sheepshead minnow ( Cyprinodon variegatus ) Acute LC 50

Estuarine/marine invert ebrates Mysid shrimp ( Mysidopsis bahia )

Eastern oyster ( Crassostrea virginica ) Acute LC 50

Acute EC 50

9Table 4. Taxonomic Groups and Most Sensitive Te st 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 EC 25 estimated) Vegetative Vigor (Tier I or Tier II no EC 25 estimated)

Freshwater vascular aquatic plants and algae Duckweed (Lemna gibba) Acute EC 25 NOAEC

Freshwater non-vascular aquatic plants Diatom (Navicula pelliculosa) Acute EC 25 EC 05

Estuarine/marine non-vascular aquatic plants Diatom (Skeletonema costatum) Acute EC 50 EC 05

a Birds are used as surrogates for terrestrial phase amphibians and reptiles (US EPA, 2004).
b Freshwater fish are used as surrogates fo r 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 whic h coumaphos may enter via runoff after a direct application of bioremendiated va t-dip solution on land and via wash-off from the cattle hide that may wade in these habitats, a nd 2) terrestrial ecosystems where terrestrial animals may come in contact with coumaphos via direct contact with treated cows, expos ure to cow hair with coumaphos residues, exposure to soil or f eed in and around treatment areas, and exposure to soil on which bioremendiated vat-dip solu tion was disposed on.

1.8.1 Receptors

The aquatic receptors likely to be exposed to co umaphos include fish, aquatic invertebrates, and aquatic stages of amphibians and plants inhabi ting 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, exposur e to cow hair with coumaphos re sidues, 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.” Operationa lly, the environmental value is re presented by an ecological entity

10and associated attributes or characteristics. The assessment endpoints for this ecological risk assessment will be survival, growth, and reproducti on of aquatic organisms and terrestrial animals that may be exposed to coumaphos. Assessment endpoints and toxicity da ta used to evaluate the asse ssment endpoints are identified in Tables 4 and 5.

1.9. Conceptual Model

The conceptual model depicts the potential ecologi cal risks associated with coumaphos uses. The model is generic and assumes that coumaphos can affect terrestrial a nd aquatic organisms if environmental concentrations are sufficiently elev ated as a result of c oumaphos label uses and coumaphos disposal. Coumaphos is an insecticid e/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 di agram 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 Chapte r. The disposal of coumaphos bioremediated dip-vat solution on land maybe equally important for aquatic and terr estrial exposure as coumaphos washoff into the water body. A review of the label provided revealed the following application rest rictions and disposal requirements:

“Do not treat areas such as dr inking cups, mangers, or troughs wh ere 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 so lution be bioremediated, and recommends the bioremediation method developed by the USDA. Th e treated solution must be transferred to shallow, concrete-lined evaporation ponds for furt her 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 evaporati on ponds must not be applie d agricultural land and should be disposed according to solid waste dispos al 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 assump tions can be made with regard to the handling of spent solution. Once in the bioremediation pon ds, the level of soluti on within the pond is maintained by evaporation and removal and proper di sposal 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 adequate ly protect aquatic life. Because application to agricultural land of a pesticide pr oduct is generally assessed by O PP, therefore, application of bioremediated coumaphos to agricultural land w ould be assessed as a potential exposure pathway.

11Roaming 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 U p take 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

• Red u ced Populat ion g rowth 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/tra nsport and effects of coumaphos in the environment.

1.10. Risk Hypotheses

Hypothesis: Non-target te rrestrial and aquatic animals and plants are at risk of di rect and indirect effects resulting from labeled us es or/and disposal of coumaphos.

1.11. Analysis Plan The analysis plan is the final step in the Probl em Formulation. During this step measures of exposure and measures of effect ar e used to evaluate the risk hypot heses and are listed in Tables 4 and 5 for a specific assessment endpoint. The RQ is obtained by dividing th e measures of exposure

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

1.11.1. Measures of Exposure

s exposure to non-target organism s, it is necessary to have information on the l of

dies

e

addition, current guidance, proc edure, 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, a nd information on the potentia coumaphos to wash-off into water when cattle wa de 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 us e in a risk assessment. Information from thos studies will be incorporated in th e registration review risk assessmen t 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 t oxicity 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 exposur e of wild birds to coumaphos B

A

T and one supplemental simulated field study (Gdl n. 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 basi s (acute oral LD 50 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 conti nuously. 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

13treated cows in an open pen. The field simulatio n study was deemed as scie ntifically 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 us ed and only 8 cows were treated. The indicate that potential pathways of exposure to birds include direct cont act 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 studi es testing coumaphos include a rat acute oral

he rat acute LD 50 study demonstrated that coumaphos is highly toxic to mammals (LD 50 value of

(RBC)

47

sect toxicity

ccording to the 1996 RED document for couma phos, the Agency deemed that the data rns, and no

ish Toxicity

reshwater fish acute toxicity

here are nine acceptable registrant submitted fres hwater 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 LD 50 study (MRID 00110597) and a rat two-year generational reproduction study (MRID 43061701).

T 17 mg/kg). The rat two-year ge neration reproduction study demons trated that cholinesterase inhibition, observed at 5 and 25 ppm was manifested as dose-related decreases in erythrocyte and plasma cholinesterase (ChE). The RBC Ch E was inhibited 31-70%, relative to concurrent controls, at 5 ppm and 53%-95% at 25 ppm. Generall y, no differences were noted between Day (or 56) and Day 91 ChE levels. Brain levels were biologically significantl y inhibited ( 30%) in F O and F 1 females. In pups, plasma and RBC ChE levels were inhibited (31%-44%) at 25 ppm on lactation day 21 but not on lact ation day 4. Based on these results, the NOEL and LEL for ChE inhibition were 1 and 5 ppm, resp ectively. 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 t oxicity 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 th e 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 (LC 50 ’s range from 0.340 ppm to 5.9 ppm).

14F reshwater fish chronic toxicity

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

arine estuarine fish acute toxicity

here is one registrant submitted marine estuarin e 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 invertebrat e acute toxicity

here are six registrant submitted freshwater invert ebrate acute toxicity studies testing coumaphos

reshwater invertebrate chronic toxicity

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

arine/estuarine inverte brate 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 grow th 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 (LC 50 = 0.280 ppm).

M

C marine/estuarine fish.

A

F

T (MRID’s 40098001, 05009242, 05017538, 41778503, and 41778504). Th ese 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, thre e of these studies were deemed acceptable and three were deemed supplemental. The results of these studies showed that coumaphos is very highly toxic to freshwat er invertebrates (EC 50 ’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 acceptabl e. 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 toxi c to very highly toxic to marine estuarine invertebrates (EC 50 values are 0.002 ppm and 0.290 ppm for the pink shrimp and eas oyster respectively).

15M arine/estuarine invertebrate chronic toxicity

urrently, there are no marine/estua rine invertebrate chronic toxici ty study data available to the

on-target Plant Toxicity

urrently no non-target plant toxicity da ta 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 th e 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 us e patterns, and no studies were required. However the Agency has currently concl uded in this problem fo rmulation 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 wa shes 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 Ag ency also presumes that there is a pote that terrestrial plants will be exposed to coumaphos via the dispos al 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 th e potential exposure to non-targ organisms such as terrestrial plants.

terrestrial toxicity studies and aquatic organism t oxicity studies respectively. These endpoints will be the proposed measures of effects that will be used to calculate risk quot ients 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 vi a the ECOTOX database.

T able 5. Summ ary of terrestr ial assessment endpoints and proposed measures of effects for the screening leve l risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint

A via Acute oral LD 50 n Acute Effects to Survival = 29.8 mg/kg (MRID 00160000) Acute dietary LC 50 = 85 ppm (MRID 112842)

A No data available *

vian Chronic Effects to

or Reproduction, Survival, and/ Growth

lian Acute Effects t M amma o Acute oral LD 50 17 mg/kg (MRID 00110597)

Survival

ammalian Chronic Effects M to NOEAL = 1 ppm (MRID 43061701) Reproduction, Survival, and/or

16Table 5. Summary of terrestr ial assessment endpoints and proposed measures of effects for the screening leve l risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint
Growth

N on-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 coum aphos, the Agency deemed th at 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 r ecently approved IR4 regi stration to use coumaphos in honey bee hives to control varroa mites and small hive beetles, the Agency w ill 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 Agen cy’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 coumapho s use patterns, and no studies were required.

T able 6. Summary of aquatic assessment endpoints and proposed measures of effects for the screening le vel risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint

reshwater Fish Acute Effects to LC 50 = 280 ppb (MR ID 40098001) F Survival

F reshwater Fish Chronic Effects to NOEAL = 11.7 ppb (MRID 43066301) Reproduction, Survival, and/or Growth

F reshwater Invertebrate Acute LC 50 = 0.074 ppb (MRID 40098001)

Effects to Survival

reshwater Invertebrate Chronic OEAL = 0.0337 ppb (MRID 431166-01) F Effects to Reproduction, Survival, N

17Table 6. Summary of aquatic assessment endpoints and proposed measures of effects for the screening le vel risk assessment of Coumaphos.

Assessment Endpoint Measurement Endpoint
and/or Growth

M arine/Estuarine Fish Acute LC 50 = 280 ppb (MRID 40228401)

Effects to Survival

M arine/Estuarine Fish rvival No data available Reproduction and/or Su

M arine/Estuarine Invertebrate LC 50 = 2 ppb (MRID 40228401)

Survival

M arine/Estuarine Invertebrate No data available Reproduction and/or Survival

A quatic 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 coum aphos 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 becaus e 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 eval uate the potential effects that aquatic plants may experience upon being exposed to coumaphos.

E qualitative characterization of th e properties of coumaphos in the environment. The only missing laboratory studies are anaerobic soil metabolis m study (162-2), aerobic and anaerobic aquatic metabolism studies (162-3, 162-4). The missing laboratory studies woul d 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 th e 2004 Screening Level Aquatic Exposure Assessment for the Use of Coumaphos in the Pacific Northwest and California, nor in the 1996 RED.

18In addition, there are no environmental fa te data for the coumaphoxon. Coumaphoxon, oxygen %

able 7, below, identifies fate and ecological stud ies, which are missing or are not acceptable, and analog of coumaphos, was detected in an aqueou s photodegradation study at a maximum of 10.2 of applied radioactivity. Coumaphoxon is couma phos’ degradate of concern due to its toxicity being greater than the toxicity of parent. Th erefore, 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 insec ticide/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 th e outdoor environment either as excess material lost during outdoor application, as material shed, washoff from animal s, and during disposal. The extent of exposure from bioremediated spent vat-dip solution can be better understood upon availability of current coumaphos disposal procedure/tech niques. If proven that these routes of expose are minimal or none, the fate studies for coumaphoxon would be waived.

T able 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 toxicit y dy was uest the study Refe r to information provided below studies for guideline 850.4400 and 850.5400 Parent – Stu not submitted Proposed to req

Anaerobic soil metabolis m 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. will characterize the potential for coumaphos It leaching to ground water or remaining in surface water. If current dispos al 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 Meta bolism (Oxygen Analog)

G uideline Number: 835.1220 Study Title: Batch Equilibrium (Oxygen Analog) Rationale for Requiring the Environmenta l Fate Studies Performed in the Laboratory Depend

m ing on how quickly and to wh at 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.

19EPA requires a series of individual laboratory studies as well as field studi es to assess the behavior and fate f a pesticide in the environment. Controlled environmen tal fate and transport laboratory studies are used to

ta

formation on

ines the pers istence of the pesticide, in this case its oxygen nalog, when it interacts with soil microorganisms unde r aerobic conditions. These studies also identify the

ticide or degradate in soil, the potential to ach into the shallow groundwater or its availa bility to surface runoff fo llowing rainfall events. o determine the persistence, mobility, and bioconcentrati on 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 inform ation on how, or by what mechanism, the pesticide degrades, the rate at which it degradates, where it go es, and what transformation products are formed. Da from these studies are used as inputs to exposur e 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 pr oduced, and thus need to be tracked, and the environmental media (e.g., soil, sediment, water, air) th at 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 understa nding of coumaphos’ oxygen analog degradation under aerobic (oxygen-rich) conditions in the laboratory, and as an input parameter for

 etter unde rstanding of coumaphos’ oxygen analog mobility in soil in the laboratory, and as an input parameter for drinking water modeling and

 studies help to determin e how fast the oxygen analog (coumaphoxon) degrades in the presence of microorganisms in differe nt 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 (S tudy 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 aroun d 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 accord ance with the 40 Code of Fe deral Regulations Part 158 aquatic plant and algal toxicity data for coumaphos are required. In addition based on the Agency’s

20TOXDATA database, very little data are available which evaluate the toxic effects of other organophosphate pesticides on aquatic pl ants 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 toxi city to algae and aquatic plants at EC 50 values ppb (MRID 42529603). Moreover according to an assess ment ("Coumaphos Analysis of Risks to Endangered and Threatened Salmon and Steelhead", A ugust 1, 2004 by Jennifer Leyhe) presenting a crude estimation of level of exposure from loss of coumapho s 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 ra nge 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 a nd 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 importa nt to evaluate the potential impact that coumaphos may have on them. of the

as low as 12

the

ecause the

How did the Agenc y make thei r decision without the data?

initially presumed th at the registered uses

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

e uatic

to calculate risk quotie nt calculations that will determine whether or not quatic plants or algae exposed to the estimated envi ronmental 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 Ag ency

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 qu otient 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.

211.11.3.1 Other Informational Needs

There i infor ency in refining the ecological risk assessment, including any species-specific effects determinati ons. 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 maxi mum number of applications

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

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

unty

tion for non-agricultural uses (e.g., forestry, reside ntial, rights-of-way) sage da ta (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 lr eady reported to the Agency

The analysis plan will be revis ited and potentially revised dependi ng 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, a pplication
pe r season f. geographic limitations on use use or potential use distributi

cr ops) 4. use history 5. median th

an d county 6. application timing (date of first application and application interval s) 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 90 th percentile number of applications – county d. total pounds per year – county

e. the year the pesticide was last us ed 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

mam malian mortalities) not a 13. monitoring data

o Registration Review docket.

2223 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 fo r ecological effects informati on. ECOTOX integrates three which ife,

ore ently,

.13. Residues of Coumaphos and Coum aphos Degradates in Water

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

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

be applied direc tly 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 databa ses - AQUIRE, PHYTOTOX, and TERRETOX - into a system includes toxicity data derived predominately from the peer-reviewed literature, for aquatic l terrestrial plants, and terrestria l wildlife, respective ly. Endpoints from ECOTOX are used to calculate risk quotients for non-targ et organisms only if these endpoi nts are acceptable and are m sensitive than the most sensitive endpoints produ ced by the registrant submitted studies. Curr the Agency’s ECOTOX database search for coum aphos open literature data is pending completion.

1

S im leach into shallow ground water. Although, no da ta were submitted for coumaphoxon, it is assum that this degradate of coumaphos is also persis tent 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 wh ere 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 stru cture effectively eliminates pathways of exposure to surface and ground water.