UNITED STATESENVIRONMENTAL PROTECTIONAGENCY WASHINGTOND.C.,20460



### PC Code: 084001


### MEMORANDUM

Date: Subject: RegistrationReview -

### Preliminary problem formulation for the Ecological Risk Assessment of Dichlorvos (DDVP)

To: Joy Schnackenbeck Special Review and Reregistration Division

From: ChristinaWendel, Biologist 

### s/rqlog Lucy Shanaman,

# hemi is* -2LA-4 7%- 

# L&+ f&qsq 

### Environmental Fate and Effects Division Through: 'Tom ~aile~, 

### w ranch chief* 

# 6 $-S,#E> WfV9? Environmental Risk Branch 2 

### Environmental Fate and Effects Division OfficeofPesticide Programs

Attached is the preliminaryproblem formulation for the ecological risk assessment to be conducted as part ofthe Registration review of the insecticideDDVP.Registration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009



## ECOLOGICAL RISK ASSESSMENT PROBLEM FORMULATION FOR: 

# Dichlorvos(DDVP)

Christina Wendel, Biologist 

### Lucy Shanaman, Chemist Environmental Risk Branch 2

Tom Bailey, Branch Chief Environmental Risk Branch 2 Environmental Fate and Effects Division Office ofPesticideProgramsRegistrationReview Ecological Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009 

### STRESSOR SOURCE AND 

### DISTRIBUTION

Dichlorvos (2,2-Dichlorovinyldimethyl phosphate), also known as DDVP is an insecticide belonging to the organophosphateclass ofpesticides. Organophosphate toxicity is based on the inhibition of the enzyme acetylcholinesterase, which cleaves the neurotransmitteracetylcholine. Inhibition of acetylcholinesterase by organophosphate insecticides interferes with proper neurotransmissionin cholinergicneurosynapses and neuromuscularjunctions.

DDVP was originallyregistered for use in the United States in 1948. Target pests are flies, gnats, mosquitoes, chiggers, ticks, cockroaches and other nuisance insect pests. Current labeled usage ofDDVP includes agricultural sites (e.g. mushroom houses); commercial, institutional and industrial sites; and domestic use in and around homes (i.e., resin strips). It is also registered for treatment of cattle, poultry, and swine. DDVP is not registered for direct use on any field grown commodities. DDVP is applied with aerosols, fogging equipment, spray equipment, and through
use of impregnated materials such as resin strips which result in slow release ofthe pesticide.

DDVP is closelyrelated to the pesticidesnaled and trichlorfon. Naled and trichlofon both metabolize or degradeto DDVP in the environment.

The risk assessments available in the docket, and which serve as the basis for this problem formulation, includethe following: Dichlorvos: Interim Reregistration EligibilityDecision 

### - Environmental Fate and Effects Division's Response to Public Comments (1

### 211012007). Revised EFED Risk Assessment for the Dichlowos Reregistration Eligibility Document (612212005). EFED Response to Registrant'sError Correction Comments on Dichlowos RED (6/22/2005). EFED Response to Public Comments on Dichlorvos Ecological Risk Assessment (8/3 

### 112006).RegistrationReview Ecological Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009 

### ECOLOGICAL EFFECTS

The purpose of this problem formulation is to provide an understandingof what is known about the environmental fate and ecological effects of the registered uses of DDVP. As described in the Agency's Overview Document (U.S. USEPA, 2004), the most sensitive endpoint for each taxa is evaluated. Assessment endpoints include directtoxic effects on the survival, reproduction, and growth of terrestrial and aquatic life, as well as indirect effects, such as reduction in prey base andlor modificationofhabitat. This problem formulation evaluates current information regardingDDVP use effects on taxa including freshwater fish and aquatic invertebrates, estuarine marine fish and invertebrates,birds, mammals, terrestrial invertebrates, terrestrial plants, and algae.

Acute (short-term) and chronic (long-term) toxicity information is characterized based on registrant-submitted studies and a comprehensive review of the open literature on DDVP. Other
sources of information includereview ofthe Ecological Incident Information System (EIIS). A summary of the available ecotoxicity information and the incident informationfor DDVP are provided below. \



### Table 1 

### and Table 2 summarizethe most sensitive ecological toxicity endpointsbased on 

### an evaluation ofboth the submitted studies and the open literature, as previously discussed. These endpoints are deemed applicableto this problem formulation for registrationreview.
A brief summary of submitted and open literature data considered relevant to this ecological risk assessment is presented below.Registration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDVP 5/14/2009


### Table 1. 

### Applicable 

### DDVP measurement endpoints and values 

### for use in 

### RQ calculations

Abundance (i.e., survival, reproduction, and growth) of individuals and populations ofbirds

Abundance (i.e., survival, reproduction, and growth) of individuals and populations of mammals

Survival of beneficialinsect populations

Survival and growth of terrestrialplants Mallard duck MRID # Avian (single dose) (Anas LD50 = 7.78 mg/kg ~~~~~~~bl~ 00160000 acute oral LDS0 platyrhynchos) ai (Hudson et al. 1984) Avian subacute LCro = 568 mglkg Acceptable MRID # 8-day dietaryLC50 (Phasianus ai 00022923 (Hill colchicus) et al. 1975) Mallard Duck MRID # Avian reproduction (Anas NOAEC = 5 mdkg Acceptable 44233401 NOAEL

. platyrhynchos) ai (diet) (Redgrave and Mansell 1997) Mammalian acute oral (single dose) Laboratory Rat LD50= 56 mglkg ai LD5o (Rattus (female) Supplemental nowegicus)

Mammalian acute inhalation toxicity LC50

Mammalian reproductive NOAEC or NOAEL

Honey bee acute

contact Laboratory Rat (Rattus 

# ' mgiL Supplemental ai nowegicus) Laboratory Rat 1 (Rattus NOAEC = 20 mgkg ai (diet) Supplemental novvegicus) Honeybee LDso= 0.495 (Apis mellifera) pglbee ai Acceptable MRID # 0005467

MRID # 00137239

Acc. # 010174 MRID # 424839001

I I I I Seedling emergence 

## I EC25 Seedling emergence No Data No Data No Data Data Gap
EC25 Vegetative vigor 

## I NOAEC LD50 =Lethal dose to 50% oftest population NOAEC =No observed adverse effect concentration LOAEC =Lowest observed adverse effect concentration LC5o= Lethal concentrationto 50% ofthe test population EC5dECzs =Effect concentrationto 50%/25% of the test populationRegistrationReview EcologicalRiskAssessment Problem Formulation for the InsecticideDDW 5/14/2009 

### Table 2. 

### Applicable 

### DDVP measurement endpoints and values for use 

### in RQ calculations

Freshwaterfish acute

freshwater fish Freshwater fish early NOAEC = 5.2 ppb

ECSo =0.07 ppb ai

Freshwater invertebrate NOEAC = 0.0058 reproductiveNOAEC 43890301 Ward

= 7350 ppb ai

individuals and communities of estuarineand marine Estuarine and marine NOAEC = 960

Estuarine and marine

invertebrate acute = 19.1ppb ai

individuals and communitiesof
NOAEC = 1.48

Standing crop or biomass and growth of aquatic plants

LD5a = Lethal dose to 50% of test population NOAEC =No observed adverse effect concentration LOAEC = Lowest observed adverseeffect concentration
m50 = Lethal concentrationto 50% of the test population EC5dEC25 =Effect concentrationto 50%/25% of the test population Freshwater green algae, cyanobacteria or

diatom 96-h IC50 for biomass. Freshwater green algae, cyanobacteriaor diatom 96-h NOAEC (or ECo5) forbiomass *lgae (unknown

species) 48 hr ECsO = 14000 ppb ai Supplemental MFUD # 40228401 (U.S. EPA, F.L. Maya 1986)Registration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009



### There havebeen 7 incidentsrelated to DDVP reported in the Environmental Incident Information System (EIIS) database (reported to the Agency fiom 1991 to 2002). Ofthese 7 incidents, 4 were of undetermined use, and 3 were registered uses.
Avian Incidents


### Six ofthe incidentswere terrestrial, with 5 related to bird kills. One incident involved an avian outdoor exposure from a site (apples) for which DDVP was never registered. Two bluebird chicks died in their nest box in the town of RedhookNew York. The nest was within 300 yards of an apple orchard. The cause of death was DDVP poisoning (reported by: Wildlife Pathology Unit,NY State Dept. Of Environmental Conservation Annual Report 1/1/94-513195. Ward Stone, Wildlife Pathologist. 1994 incident). Another incident involved a registereduse of DDVP crystals in treated feed that resulted in 8 

### mallard ducks dying in an 

### agricultural area. Afiother incident involved an avian exposure resulting fiom an undetermined use of DDVP in British Columbia, Canada. The red tailed hawk was incapacitated as a result of secondary poisoningby DDVP (1 1/16/97). The last two incidents involved the use of DDVP in the home residence resulting in canary deaths (6 total deaths).
Mammalian Incidents


### There is one mammalian incident reported involving indoor exposureto animals. Amvac Chemical Corp. (Letterto Agency Dated 7/3/95) reported potential adverse effects exposure relating to a pest strip in which several exotic and wild native and non-native animals that included skunks and several fennec foxes (native of Egypt) were in a room ofroughly 4000 cubic feet. The room had a pest strip placed in it 3-4 days previouslyto control insects. The pest strip was labeled as covering 1000 cubic feet. Four fennec fox pups died. A veterinarian treated three other pups with atropine; two recovered. The foxes were the only animals that recovered. Two ofthe animals recovered after treating with atropine, indicatingit is possible that the cause ofpoisoning was exposureto DDVP fumes. Aquatic Incidents


### One aquatic incident ofundetermined use in Tennessee involving fishkills was reported affecting 379 organisms (speciesundetermined). No residue analysis was conducted. Currently, no systematicor reliable mechanism exists for the accurate monitoring and reporting of wildlife kill incidents to the Agency.

# oreo over, before a pesticide incident can be reported or investigated,the dead animals must firstbe found, In the absence ofmonitoring following pesticide applications, kills are not likely to be noticed in ago-environments which are generally away from human activity. Even if onlookers are present, dead wildlife species,particulqrly small song birds and mammals, are easily overlooked, even by experienced and highly motivated observers. Even in sparse vegetative cover, wildlife carcass detection is difficult and as vegetative cover increases the difficultyin detection is exacerbated. Under some circumstances intoxicated animals may seekheavy cover before dying which decreases the probability ofRegrgrstration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDVP 5/14/2009 

### detection further. Poisoned birds may fly from the sites, succumbing outside ofthe area or scavengers may remove carcasses before they can be observed, significantly reducing the chance of detection.

, 

### Balcomb (1986) reported that songbird carcasses removal rate ranged fiom 62 to 92 percent in the first 24 hours followingplacement, with a mean loss at 24 hours of 75% (S.D. 2 12.4). Overall,by the end ofthe 5-day monitoringperiod, 72 of the 78 carcasses had been removed by scavengers.In addition, the number of birds per acre alone, not considering these other factors, makes detection ofkills difficult. Best (1990) reported fiom 0.57 live birds per acre in the center to 2.8 live birds per acres in the perimeter of corn fields in Iowa and Illinois. Even if all the birds in a field were killed and remained on the field, the probability of observing carcasses, particularlywhen not systematically searching, at these densities,is not high. Research has shown that even when intense systematic searches are conductedby highly trained individuals for placed carcasses in agro-environments, recovery rates rarely exceed 50 percent (Madrigal et a1.1996).

Even if dead animals are observed, they might not be reported to the Agency. Persons unfamiliar with the toxicity ofpesticides to non-target speciesmay fail to associatethe findingwith the pesticide application, especiallyifthe two events are separated by several days and only a few birds are observed dead. Even if the association is made, the observer must be aware or have the motivation to find out where to report the incident. Therefore, the reporting of a few dead birds associated with the use of a chemical is believed to provide evidencethat substantial effects may be occurring.

Volatilization (1.2 x 

### rnrn Hg) is expected to be the main route of dissipation for DDVP in the environment. DDVP is not expected to persist in either soil or water. DDVP is susceptible to both hydrolysis (tin = 

### 5 days) and photolysis (tin = 

### 10-17days). DDVP also degrades in aerobic (til2= 

### 0.43 days) and anaerobic (tli2 = 

### 6.3 days) environments.

DDVP is expected to be mobile in the open environment. Thehigh vapor pressure indicates that DDVP will dissipate primarily through volatilization. This is confirmed by two submitted terrestrial field dissipation studieswhich report that DDVP was measured in the air above the field test plots located in Missouri and California at 12.5% (MRID 44386701) and 89.2% (MRID 44297701) of the total applied DDVP, respectively. The organic carbonpartition coefficients



## (LC = 

### 15-41) for DDVP predicts mobility in water. A summary of the environmental fate properties maybe found in Table 3 below.RegistrationReview Ecological Risk Assessment Problem Formulation for the InsecticideDD~P 5/14/2009 community water systems in a few states in 2004. In 2001, PDP analyzed 214 finished drinking water samples from CA andNY. In 2002 and 2003, PDP sampled 371 and 699 finished drinking water samples, respectively, in CA, CO, KS, NY, and 

### TX. In 2004, PDP sampled raw and finished water fiom 171 community water systems fiom MI, NC, OH, OR, PA, and WA. DDVP was one of the analytes. No detectable residues ofDDVP were found at limits of detection-(LOD)of 0.4 

### - 22.5 pptrillion. Naled and trichlorfon were not among the analytes tested, but PDP would have detected DDVP coming fiom naled and trichlorfon.
However, the PDP monitoring of water fiom community water systems are not completely reflective of the drinking water consumed by the population for the following reasons: the PDP samples large community water systems in a limited number of states; the sampling sites are not necessarilyin DDVP, naled, and trichlorfonuse areas, and the data may not be reflective of drinking water concentrations in areas of high dichlorvos use; the community water systems sampledby PDP are generallydeep ground water or surface water systems; and the PDP does not sampleindividual, private wells. Use of the PDP data would not be protective ofpeople whose drinlung water source is a private well.

e


### Clean Water Act

DDVP is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on informationprovided at 

### http://oaspub.epa.gov/trndl/waters list.impairments?p impid=3. The Agency invites submission of water quality data for this To the extent Fossible, data should conform to the quality standards in Appendix 

### A of the OPP Standard OperatingProcedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP's Registration Review Risk Assessment and Management Process (see: 

### http://www.epa.gov/oppfeadl 

### /cb/p~dc/2006/november06/session1- sop.~df), in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

For DDVP and pesticides in general, the ecosystems at risk are those in close proximity to the
use areas. These would include the DDVP use sites and the surroundingterrestrial habitats, and water bodies directly adjacent to treated areas (e.g. feedlots) that may receive chemical residues via 

### drift, volatilization, or runoff. Within water bodies, the water column, sediment, and pore water are all compartments of concern; however, grven DDVP's solubility it is most likely to be


# . found in the water column. Organisms ofpotential concern broadly includebirds, mammals, reptiles, fish, amphibians, and terrestrial and aquatic invertebrates,plants, beneficial insects, and amphibians.

The assessment endpoints are intended to reflect population sustainabilityand community structure within ecosystems and hence relate back to ecosystems at risk. If risks are expected forRegistration Review Ecological Risk Assessment Problem Formulation for theInseciicideDDVP 5/14/2009 

### given speciesltaxabased on the screening-level assessment, then risks might be expected to translate to higher levels ofbiological organization.
The predominate uses of DDVP in California (the only usage data availableto the Agency) were the impregnated pest strip and structural pest control. Table 4 

### gives estimates of DDVP usage in California. The uses of DDVP which may pose a potential risk to terrestrial and aquatic organisms would be insect control on dairy and beef cattle. Table 5 

### gives estimates of DDVP use on dairy cattlefor 1999,2001, 

### and 2006 and Table 6 gives estimates of DDVP use on beef cattle for 1997 

### and 1999. 

### DDVP use on dairy cattle and beef cattle appears to have decreased.

I 

# I CHICKEN 

### 1 45.20 

### 1 59.15 

# 1 I
COMMODITY FUMIGATION DATE 254.84 47.71 607.91 1,760.90 1.464.28 FOOD PROCRESSING PLANT FUMIGATION, OTHER LANDSCAPEMAINTENANCE POULTRY REGULATORYPEST CONTROL



# I STRUCTURAL PEST CONTROL I I I 

### 1 1.775.58 

### 1 1,974.86 

### 1 1.491.48 

# I 370.56

533.87 59.30 230.49 23.52 1.77 RESEARCH COMMODITY RIGHTS OF WAY STORAGE AREAIBOX

Prepared: November 7,2008 Cal DPR Data: http://www.cdpr.ca.gov/docs/pur/purmain.htm Empty cells indicate no available usage. 549.50 114.89 619.19 13.77

22.60

16.39 23.11 1.25 59.67

VERTEBRATE CONTROL Chemical Total 19.69 24.22 30.21

3.807.15



### Table 5. 

### DDVP Use on 

### Dairy Cattle and 

### Dairy for 1999,2001,2006 Dairy Cattle Year 

## 1 National Use 

## I RateIhead~Year
1999 2001 2006 13.17 4,898.19

Number cattle ( OhCattle treated 14.80 6.527.38

(lb) 96,200 9,000 4,900 (lb) 0.25 0.03 0.01 treated 384,800 300,000 245,000 4.2 3.3 2.7Regisfration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDW ' 5/14/2009

Assessment endpoints are defined as "explicit expressionsof the actual environmental value that is to be protected." Defining an assessment endpoint involvestwo steps: 1) identifjing the valued attributes of the environment that are considered to be at risk; and 

### 2) operationally defining the assessment endpoint in terms of an ecological entity (i.e., a community of fish and aquatic invertebrates) and its attributes (i.e., survival and reproduction). Therefore, selection of the assessment endpointsis based on valued entities (i.e., ecological receptors), the ecosystems potentially at risk, the migration pathways ofpesticides, and the routes by which ecological receptors are exposed to pesticide-related contamination. The selection of clearly-defined assessment endpoints is important because they provide direction and boundaries in the risk assessment for addressing risk management issues of concern. Changes to assessment endpoints
are typically estimated from the available toxicity studies, which are used as the measures of effects to characterize potential ecological risks associated with exposure to a pesticide, such as DDVP. 

### Table 6. 

### DDVP Use on Beef Cattle for 

### 1997 and 1999 Beef Cattle

To estimate exposure concentrations, the ecological risk assessment considers a single application at the maximum application rate to fields that have vulnerable soils. The most sensitive toxicity endpoints are used from surrogate test species to estimate treatment-related direct effects on acute mortality and chronic reproductive, growth and survival assessment endpoints. Toxicity tests are intended to determine effects ofpesticide exposureon birds, mammals, fish, terrestrial and aquatic invertebrates, and plants. These tests include short-term acute, sub-acute, and reproduction studies and are typically arranged in a hierarchical or tiered system that progresses from basic laboratory tests to applied field studies. The toxicity studies
areused to evaluatethe potential of a pesticide to cause adverse effects, to determine whether further testing is required, and to determine the need for precautionary label statements to minimize the potential adverse effects to non-target animals and plants.

Year

1997 1999

DDVP is classified as very highly toxic to birds on an acute oral basis, moderatelytoxic to birds
on a sub-acute dietary exposurebasis, and is classified as moderately toxic to mammals on an acute oral exposure basis. It is also highly toxic to the honey bee on an acute basis. Indirect effects on species consuming these animals are also possibly a concern due to loss ofprey base.

DDVP is very highly toxic to both freshwater and in marinelestuarine invertebrateson an acute exposure basis. It is highly toxic to freshwater fish and moderately toxic to marinelestuarine fish
on an acute basis. Chronic effects in aquatic animals includereduced survival (freshwater and estuarinelmarine fish), reproduction (freshwater invertebrates),and growth (fi-eshwater and estuarinelmarine invertebrates and estuarinelmarine fish). Site

Beef Cattle Beef Cattle National Use (Ib) 32,700 18,700 Rate Ihead Iyr Qb)
0.01 0.01 Number of Cattle treated

3,270,000 1,870,000 % Cattle treated as percentage of all insecticides used 9.5 5.5RegistrationReview Ecological Risk Assessment Problem Formulation for the InsecticideDDVP 5/14/2009



### In order for a chemical to pose an ecological risk, it must reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide
moves in the environment fi-oma source to an ecological receptor. For an ecological exposure pathway to be complete, it must have a source, a release mechanism, an 

### environmental transport medium, a point of exposurefor ecological receptors, and a feasible route of exposure.
The conceptual model (Figure 1) 

### depicts the potential pathways for ecological risk associated with DDVP use. The conceptual model provides an overview of the expected exposure routes for organismswithin the DDVP action area. The focus of this model is application via spray (aerial and ground).

Based on 

### an examination of the physical/chemical properties ofDDVP, the fate and disposition in the environment, and method of application, a conceptual model was developed that representsthe possible relationshipsbetween the stressor, ecological receptors, and the assessment endpoints. The major transport pathway for DDVP is expected to be volatilization. While DDVP is also expected to be mobile in water, short laboratory half-life values in soil and water, along with a high vapor pressure, will allow volatilizationto dominate as the main route of dissipation in the open environment.Registration Review Ecologicnl Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009 

### FIGURE 1. ECOLOGICAL CONCEPTUAL DIAGRAM FOR 

### DDVP

TRANSPORT

EXPOSURE

ROUTE 

# 1 RECEPTORS Application ofDichlorvos (DDVP) via Sprayer, Mister or Fogger

--------3----------- ) Leach~ng (Infiltrat~on) I Percolabon 

## I I I-- ---------,---, - ---,
,--- 

### L-----

+----

## 4 Groundwater 

### I

1--------- J

Populabon lnd~v~dual Reduced Invertebrates, Populat~on Vertebratks Growth Reduced Su~~val, Growth, - Re~roduct~on

In Registration Review, pesticide ecological risk assessments will follow the Agency's Guidelines for Ecological Risk Assessment, u;ill be consistent with the paper titled "Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental ProtectionAgency" ("Overview Document") (January

### 2004), and will be done in accordance with Section 

### 7 of the Endangered Species Act. Previously completed screening level risk assessments and exceedances of Agency levels of
concern indicate a need to further examine and refine acute risk to terrestrial animals. Analysis of potential indirect effects on listed speciesis also required. This analysis plan will be revisited and may be revised dependingupon the data available in the open literature and the information submitted by the public in response to the opening of the RegistrationReview docket.

DDVP's fate characteristics, results of toxicity data, and use pattern including multiple outdoor applicationsto cattle suggests potential risk concerns to terrestrial and aquatic organisms. The range ofpotential exposure of DDVP to non-target organisms can vary greatlybased on the applicationmethod, number of applications applied, application intervals, and number of cattle treated.RegistrationReview EcologicalRiskAssessment Problem Formulation for the InsecticideDDW 5/14/2009 

### The registered uses of DDVP, which suggest a potential risk concern to terrestrial and aquatic organisms, would be insect control on dairy and beef cattle. All other uses are indoor uses or spot treatments. Themethod of spray application varies widely with varying degrees of potential exposures. In the case of dairy herds, smaller herds are most likely treated as a group rather than individuallyby small hand held sprayers (Thomas 2007), larger operations favor automated systemsthat trigger sprays as animals enter or exit the milking parlor. The most effective method of applicationin large beef cattle operationsis the mist blower (Holscher 2007); however, other applicationmethods include foggers, hydraulic spryerhandguns and back rubbers. The Agency's analysis indicates that when DDVP is used, it is applied in approximately 37 applicationsper year (Pest Management StrategicPlan for Lactating (Dairy) Cattle -

### North Central Region, 2004). The frequentuse suggests that when a herd is treated, such treatment is often done on a daily or every-other-day basis during the part of the season insects are present. With regard to the exposurevariation associated with the number of cattle treated, the Agency's analysis indicate that of states reporting DDVP usage on dairy cattle, the average herd sizeranges from 44 to 800 head per dairy operationwith a national averageherd size of 126. Beef cattle herd sizesrange from less than 6 to more than 4,539 head perbleef operationwith a national average herd size of 43 head. On a feedlot, there is a range of 174

### - 622 headlacre.
Based on DDVP's use patterns, there are uncertainties associated with potential; 1)risks to passerine birds, 2) inhalation risks to birds; 3) risks to terrestrial and aquatic plants; and 4) risk to aquatic organisms with DDVP use on beef and dairy cattle.

In 

### addition, given that volatilizationis potentially a major route of dissipation for DDVP, there is
a need to assess the volatility associated with DDVP use. Also, available toxicity data indicate that DDVP is very highly toxic to avian species on an acute oral basis and is classified as category I1 

### for acute inhalation toxicity to mammals. In 

### order to fbrtherunderstand the volatility of DDVP in the field and laboratory, as well as determine any toxicological responses, volatility and acute avian inhalation studies are being requested. The acute avian inhalation study and volatility data will be used to assesspotential acute risks associated with avian inhalation.

Due to DDVP's use pattern, specifically the outdoor insecticidal use on dairy and beef aattle, there is a potential risk to non-target terrestrial and aquatic plants. Currently, there is na acceptable data conducted with DDVP on terrestrial or aquatic plants. Terrestrial and aquatic plant toxicity data would assist in the evaluation of potential plant risks associated with DDVP
use.
Due to the potential for DDVP to volatilize there is some uncertaintyregarding the exposure of DDVP to the aquatic environment and subsequent potential risks to aquatic organisms. 

### A quick
screen ofthe potential exposure to DDVP in surfacewater indicate that the potential EECs for aquatic exposure are greater than some toxicity endpointsidentified in available fish and aquatic invertebrate studies. This screen, however, did not consider volatility. During registration review, aquatic risks will need to be assessed with a Tier 2 

### model whch addresses the potential volatility of a compound. The application of DDVP for each animal was derived after review of the label (The insecticide is 10lblgal DDVP = 

### 100% solution, dilute with 99 gal of water to get a 1 %

### treatment solution and you have 12,800 fl 

### oz which contains 10lbs of DDVP or 0.000781bsRegistrationReview EcologicalRiskAssessmerzt Problem Formulution for the InsecticideDDW 5/14/2009 

### DDVPIfl oz. Each animal is treated with 2 fl 

### oz. therefore; each animal is treated with 0.0015 lbs. of DDVP). Also, degradate information for DDVP is limited, a more through analysis of the followingdegradates, and the risk associated with them needs to be examined. Major degradates of DDVP are 2,2-dichloroacetic acid, 

### 2,2-dichloroacetaldehyde, desmethyl dichlorvos, and glyoxylicacid During RegistrationReview, the terrestrial risks associated with DDVP use will be assessed with T-REX, TerrPlant and AgDRIFT. Potential aquatic risks will be assessed using with a Tier 2 

### model which addresses the potential volatility of DDVP.
If the planned ecological risk assessment indicates that DDVP exceeds the Agency's Level of Concern for Listed species, either directly or indirectly, a preliminary "May Affect" determination will be made for the affected taxa (e.g., birds, mammals, fish, invertebrates, etc).

, 

### A map of the DDVP use "footprint," consisting of all land cover types for whch the LOC is exceeded will be generated, along with a narrative description ofthe area outside the footprint where effects are expected to occur. These maps and narrative descriptions will be provided to

- 

### the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) for them to determine which Listed species may be affected.

The data that are needed for registration review include:
A. Environmental Fate
The fate date set for DDVP is complete except for the following. Field and Laboratory Volatility studies, which are needed because volatilizationis expected to be the main route of dissipation for DDVP in the environment.
835.14 10Volatility 

### -- laboratory 835.8100 Volatility

### -- field



### B. Ecological Effects

Data Gaps 

### Several toxicity studies are needed to better assess the potential risk of DDVP exposure to non-target organisms. The studies listed below should be submitted to increase certaintyin the risk estimation.

850.4100 (123- 1 a) Terrestrial plant toxicity, Tier I 

### (seedling emergence) 850.4150 (123-la) Terrestrialplant toxicity, Tier I 

### (vegetativevigor) 850.5400, 850.4400 Tier 1 aquatic plant growth 850.2100 Acute Avian, Passerine 885.4100 Avian Inhalation, Tier IRegistrationReview EcologicalRisk Assessment Problem Formulation for the InsecticideDDW 511412009


### The Agency will also conduct a search of the open literatureto ensurethat all best available science is utilized. The Agency uses the ECOTOX database as its mechanism for searching the open literature for ecological effects information. ECOTOX integrates three previously independent databases 

### - AQUIRE, PHYTOTOX, and TERRETOX 

### - into a system which includes toxicity data derived predominatelyfrom the peer-reviewed literature, for aquaticlife, terrestrial plants, and terrestrial wildlife,respectively.
The analysis plan will be revisited and may be revised depending upon the data available in the open literature and the information submitted by the public in response to the opening of the Registration Review docket.

The Environmental Fate and Effects Division (EFED) has completed a Data Call-In (DCI) table for 

### DDVP environmental fate and effects data gaps identified in registration review. The effects data gaps may changeif relevant toxicity data are identified fiom the ECOTOX literaturereview. The attached DCI 

### tables, which include the guideline number and study title for required data, also provides a rationale for requiring the data, an explanation ofhow the data will be used, and a brief description ofhow the data could impact the Agency's future decision-making.

Guideline Number: 835.1410,835.8100 StudyTitle: FieId andLaboratory Volatility Studies Rationale for Requiringthe Data SinceDDVP has a vapor pressure of 

### (1.2 x 1 0-2 

### rnm Hg), it triggers the requirement for field and laboratory volatility studies. These studies will assist the Agency in understanding the vapors resulting from volatilization of DDVP as well as to what degree volatilization occurs. This study will help determineany biological effects in non-target organisms at some distance from the treated site. This is au~licable sinceDDVP can be used on dairv and beef cattle. 

# I I I Practical Utility ofthe Data 

# I

How will the data be used? There are no currently available or acceptable volatility studies that track the formation and decline of DDVP and its degradates. These data will be used to characterizethe environmental fate of DDVP. For quantitative exposureestimation, these data will be used to determine appropriate inputs for simulation modeling.
How could the data impact the Agency's future decision-making? Without these required data, the fate of DDVP cannot be fully characterized. In the absence of acceptabledata, conservative assumptionswill be made. Therefore, the use of DDVP might need to be restrictedin areas where endangered species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for DDVP which are unnecessarily
severe.Registration Review Ecological Risk Assessment Problem Formulationfor the InsecticideDDVP

including the likelihood ofpotential risks to endangered species, eitherby direct effects or by indirect effects such as reducing food sourcesto listed predators and scavengers. Results ofthis study would be used to calculate acute risks topasserine species.fi-om exposure to DDVP and to identify whether current labeling is appropriateand whether fk-thermitigation is necessary.
How couldthe data impact the Agency's future decision-making? If the data indicate that DDVP poses a significant acuterisk to passerine birds, the Agency may explore additional decision options to minimize the risk of DDVP to these species. If htwe endangered species risk assessments areperformed without these data, the Agency would have to assume that DDVP "may affect" passerine birds directly and other endangered species indirectly through loss ofprey. The lack of these data will limit the flexibility the Agency and registrants have in complying with the Endangered Species Act and could result in inappropriate mitigation
measures. Guidelipe Number: Special Study Study Title: Acute Avian inhalation, Tier I Rationalefor Requiringthe Data 

### Volatilizationis potentially a major route of dissipation for DDVP. 

### Also, available toxicity data indicate that DDVP 

### is very highly toxic to avian species on an acute oral basis and is classified as categoryI1 for acute inhalation toxicity to mammals. In order to determine toxicological responses associatedwith the volatization of DDVP, 

### an acute avian inhalation study is being requested Practical Utility of the Data

--- 

## I How will the data be used? 

## 1

The acute avian inhalation data are needed to asses potential acute risks to birds associated with the inhalation route of exposure. The data will allow the Agency to better assess the risks to these organisms, including the likelihood of potentialrisks to endangered species, either by direct effects
or by indirect effects such as reducing food sources to listed predators and scavengers. Results of this study would be used to calculate acute risks to birds fi-omexposure to DDVP and to identify whether current labeling is appropriate and whether further mitigation is necessary.
How could the data impact the Agency's future decision-making? If the data indicate that DDVP poses a significant acute risk to birds, the Agency may explore additional decision optionsto minimizethe risk of DDVP to these species. If future endangered species risk assessments are performed without these data, the Agency would have to assume thatRegcgcstration Review Ecological RiskAssessment Problem Formulatwn for the InsecticideDDVP 5/14/2009 DDVP "may affect" birds directly and other endangered species indirectlythrough loss ofprey. The lack ofthese data will limit the flexibility the Agency and registrantshave in complying with the Endangered SpeciesAct and could result in inappropriate mitigationmeasures.

most habitats and significantly contributeto overall environmental quality, and therefore a solid understandingofthepotential risks to plants is essential for sound environmental management.
Since the DDVP RED was signed, the Agency has finalized its update to the data requirements in 40 CFR Part 158. In these updated data requirements, which were promulgated on October 26, 2007, Tier I seedling emergence (guideline 850.4100), and Tier I vegetativevigor (guideline 850.4150) are required for terrestrial uses. DDVP is registered for terrestrial use, and therefore these data are required under the new 40 CFR Part 158 data requirements. Practical Utility of the Data How will the data be used? The data will be used to estimate potentialrisks to terrestrialplants, includingthe likelihood of potentialrisks to endangered species, either by direct effects or by indirect effects, and to reduce uncertainties associated with the current ecological risk assessment. By refiningthe assessment, the Agency will be able to determinewhether current labelingis appropriateand whether further mitigationis necessary.
. In the absence of Tier I data, risks to terrestrialplants will be presumed.
How could the data impact the Agency's future decision-making? These data, once submitted, will allow the Agency to characterizetherisk of DDVP to terrestrial and aquatic ecosystems. Primary producers (i.e.plants) provide oxygen, food and habitat vital to ecological processes. Therefore, a solidunderstanding of the potential risks to plants is essential in order to assessthe environmental risks the use of DDVP may pose. If the data indicate that DDVP poses significant risks to these plant species, the Agency may explore additional decision optionsto minimize the risks to these species.
The lack of these data will limit the flexibility the Agency and registrantshave in complying with the Endangered Species Act and could result in use restrictions for DDVP which may otherwisebe avoided, or which are unnecessarily severe.

Guideline Number: 850.4400,850.5400 Study Titles: 

### Tier 1 aquatic plant growth
Rationale for Requiringthe Data DDVP toxicity data for vascular and non-vascular aquatic plants are not available. Tier 1 aquatic plant toxicity data would provide enough data to screen for potential $quatic plant risks associated with DDVP use. Plants formthe basis of most habitats and significantlycontribute to overall environmental quality, and therefore a solidunderstanding ofthe potential risks to aquatic plants is essential for sound environmental management. 

# I Sincethe DDWRED was signed, the Agency has finalized its update to the data requirements in 

# IRegistration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDP 5/14/2009

imatepotential risks to aquatic vascular and non-vascularplants,
indirect effects, and to reduce uncertainties associated with the current ecological risk assessment. By refining the assessment, the Agency will be able to determinewhether current labeling is appropriate and whether further mitigation is necessary. In the absence of Tier I data, risks to both vascular and non-vascular aquatic plants will be presumed.
How could the data impact the Agency's future decision-making? Because aquatic vascular and non-vascular plants formthebasis ofthe food chain for aquatic habitats and significantly contribute to overall water quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental risk management decision-making. These data, once submitted, will allow the Agency to characterizethe risk of DDVP to terrestrial and aquatic ecosystems. Primary producers (i.e.plants) provide oxygen, food and habitat vital to ecologicalprocesses. Therefore, a solidunderstanding of the potentialrisks to plants is essential in order to assessthe environmental risks the use of DDVP may pose. If the data indicate that DDVP poses significant risks to these plant species, the Agency may explore additional decision options to minimize the risks to these species.Registration Review Ecological Risk Assessment Problem Formulation for the Insecticide DDVP 5/14/2009

National Resource Defense Council. 2006. Petition of Dichlorvos (DDVP) Revised Ecological Risk Assessment. June 2,2006. Attn: Docket ID Number OPP-2002-0302. U.S. Environmental Protection Agency. 1995. ~dtice of Preliminary Determination (Position Document 213) in the Federal Register September 28, 1995. Washington, D.C.

U.S. Environmental ProtectionAgency. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of Research and Development, Washington, D.C. EPA/630/R-951002F. April 1998. U.S. Environmental Protection Agency. 2000. Risk Characterization Handbook. Science Policy, Council, U.S. Environmental ProtectionAgency, Washington, D.C. 20460. EPA 100-B00-002. December 2000.

U.S. Environmental ProtectionAgency. 2004. Overview of the Ecological Risk Assessment Process in the Office of PesticidePrograms, U.S. Environmental Protection Agency. Endangered and Threatened Species Effects Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C. January 23,2004.

U.S. Environmental ProtectionAgency. 2005a. DDVP RED 084001 D312675 January 3 1,2005 Dichlorvos: Interim Reregistration EligibilityDecision-Environmental Fate and Effects Division's Response to Public Comments. Office ofPrevention, Pesticides and Toxic Substances, Office of PesticidePrograms, Washington, D.C.

U.S. Environmental ProtectionAgency. 2005b. Revised EFED Risk Assessment for the Dichlorvos Reregistration EligibilityDocument. June 22,2005. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, 

### D.C.

U.S. Environmental ProtectionAgency. 2005c. EFED Response to Registrant's Error Correction Comments on Dichlorvos RED. June 22,2005. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs,Washington, D.C.

U.S. Environmental ProtectionAgency. 2006a. EFED Response to Public Comments on Dichlorvos Ecological Risk Assessment 084001 D290605. March 20,2006. Office of Prevention, Pesticides and Toxic Substances, Office of PesticidePrograms, Washington, D.C.

U.S. ~hvironmental ProtectionAgency. 2006b. Interim Reregistration Eligibility Decision for Dichlorvos (DDVP). Office of Prevention, Pesticides and Toxic Substances, Office of PesticidePrograms, Washngton, D.C. June 2006.Registration Review Ecological Risk Assessment Problem Formulation for the InsecticideDDW 5/14/2009


### U.S. Environmental ProtectionAgency. 2006c. EFED Responseto Public Comments on Dichlorvos Ecological Risk Assessment. August 3 

### 1,2006. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C.
U.S. Environmental ProtectionAgency. 2007a. Responseto petitionbrought by the National Resource Defense CouncilNovember 16,2007. Office of Prevention, Pesticides and Toxic Substances, Office of PesticidePrograms, Washington, D.C.

U.S. 

### Environmental ProtectionAgency. 2007b. Dichlorvos (DDVP) Usage on Dairy Cattle, Beef Cattle, Swine, and Poultry (Animals and Facilities)'D340495Decision # 

### 379882. Product Review Panel June 27,2007 and November 7,2007. Biological and Economic Analysis Division (BEAD). Office of Prevention, Pesticides and Toxic Substances, Office of PesticidePrograms. Washington, D.C.
U.S. Environmental ProtectionAgency. 2007c. DDVP RED 084001 D292980 December 10, 2007. Revised EFED Risk Assessment for the Dichlorvos Reregistration Eligibility Document. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs. Washington, D.C.