### UNITED STATESENVIRONMENTAL PROTECTION AWNCY WASHINGTON, D.C. 20460 OFFICE OF PREVENTION,PESTICIDES,

AND 

### TOXIC SUBSTANCES 

### PC Code: 029841 DB Barcode 377095 Date: May 24,2010
MEMORANDUM Subject: EFED Responseto a FIFRA Section 18 Emergency Exemptionfor

# i Dicamba co-formulated with 2,4-D (LatigoTM) Use on Teff grown for grain, seed, and hay to controlbroadleaf weeds. Requested by the Oregon Department of Agriculture. I 

### To:

From:

Thru: Marcel Howard, Risk Manager Risk Integration,Minor Use & 

### Emergency ResponseBranch Registration Division (7505P) USEPA Office ofPesticide Programs Tiffany Mason, Environmental Engineer Michael Wagman, Biologist EnvironmentalRisk Branch I1 Environmental Fate and Effects Division (7507P) USEPA Office of Pesticide Programs William P. Eckel, Acting Branch Chief Environmental Risk Branch I1 Environmental Fate and Effects Division (7507P) USEPA Office of Pesticide Programs The Oregon State Department of Agriculture has requested a FIFRA Section 18 emergency exemption for ground application of 2,4-D formulated with dicamba (batigo, EPA Reg # 

### 5905-564) to controlbroadleaf weeds in teff grown for hay, seed and grain. In the case ofthe product formulationsof active ingredients, each active ingredie t is subjectto an individual risk assessment forregulatory decision regarding the acti

# 3 e ingredienton a particular use site. This assessment analyzes the risk associateddith dicamba use. EFED has reviewed the risk to non-listed and listed speciesin Ore& based on the proposed applicationmethod and rate, and the availability of viable exposurepathway and toxicological data. EFED concludes that there may be 

### an adverse risk from dicamba applicationto teff for amphibians, reptiles, birds, insects and non-target plants (especially dicots). Dicamba use adverse risk from acute dietary-based exposure and chronic exposureto is no chronic freshwateror saltwaterfish and invertebrate data. In the data, EFED assumes that there is potential chronic risk to these

### analysis of endangered species was run and is attached in Appendix E. A buffer analysis was conducted for dicambausing AgDrift. This analysis concluded that a buffer of 76 feet was necessaryto reduce effective exposure concentrationsbelow the Agency's level of concern (LOC).


## ApplicationMethod and Timing
The Oregon Department of Agriculture (ODA) isrequesting the use of Dicamba formulated with 2,4-D (Latigo) to controlbroadleaf weeds in teff (Erogrostis teJ) grown for hay, seed and grain. Specifically, the pest species to be controlled are kochia (Kochia scoparia), redroot pigweed (Amaranthusretrofexus), common lambsquarters (Chenopodiumalbum), common purslane (Portulaca oleracea), hairy nightshade (Solanum sarrachoides), field bindweed (Convolvulusarvensis). The ODA claims that there are no selectivebroadleaf herbicides registered for use on teff, which significantly decreases the quality and yield of hay, grain and seed. The emergency condition has been createdby a sharp increase in the weed seed bank ofbroadleaf weeds, especially due to herbicide resistance in kochia and redroot pigweed, the latter of which emerges at the same time as teff which is planted in June. Hay from teff does not 

### dry properly when slow-dryingbroadleaf weeds are interspersed with the slender teff grass blades. Excessive moisture results in moldy hay, which is unhealthy for animals to consume. Teff seed or grain contaminated with redroot pigweed seed is particularly difficult to clean out, resulting in significant seed cleaning costs. Latigo is an emulsifiable concentrateof 24.62% 2,4-D acid 

### (2,4-Dichlorophenoxyacetic acid) and 18.28% dicamba acid 

### (3,6-dichloromethoxybenzoicacid). LatigoTM (EPA Reg # 

### 5905-564) is used to controlbroadleaf weeds in pastures,rangeland, grass (hay, silage), sugarcane, wheat, conservation reserveprogram land, and certain noncrop sites. The Oregon Department of Agriculture estimates that a maximum of 3,830 acres ofteff would be treated from May 21, through August 21,2010 for a total maximum amount of 598.43 gallons (1,436.22 lb a.i. 2,4-D acid and 1,077.17lb a.i. dicamba acid) used. The proposed use counties are Benton, Crook, Deschutes, Douglas, Jefferson, Klamath, Lake, Lane, Malheur, Marion, Polk, Tillamook,Washington, and Yamhill. According to the proposed label, Latigo can be applied at the maximum rate of 20 fl.oz per acre (0.38 lb 2,4-D acidacre and 0.28 lb dicamba acidacre), and can be applied once per growing seasonby ground spray technologies. The emergency exemptionlabel states that all applicable directions, restrictions, and precautionson the Latigo label must be followed. The "Environmental Hazards" statements relevant on the Latigo label include1:

1 Note that the section 18 label, at this time, does not show these statementson the label; however, these statements are on the proposed section3 label, and the documentation that came with the section 18label. These environmentalhazard statementsmust be placed on the section 18label as stated in the proposed package for the section 18label.

### This pesticide is toxic to aquatic invertebrates.Do not apply directlyto watkr, areas where surface water is present, or to intertidal areas below the mean high water mark. Drift or runoff may adversely affect aquatic invertebrates and non-target plpts. Do not apply when weather conditions favor drift from target area. Do not contaminate water by cleaning of equipmentor disposing of equipl+ent washwaters or rinsate. Caution should be exercised when handling 2,4-D pesticidesto prevent contaminationof groundwater supplies.Use of a closed system for mixinglor transferringthis pesticide will reduce probability of spills. 

# ~ Mixinglloading equipmentplaced on impervious pads to contain spillswill help prevent groundwater contamination.


## Exposure

- 

## Pathways of Concern and Fate Properties

- 

## of Latigo
The new proposed use of dicamba and 2,4-D may result in drift onto plants, soil, adjacentto a treated field. Foliar application ofthe dicamba and 2,4-D mixture, ground application,will result in residues on dietary items forbirds and on the use pattern for the mixture, the main exposurepathways for are direct exposurevia consumptionof food items and from direct invertebrateslinsectssuch as honeybees. Aquatic organismsmay dicamba and 2,4-D mixture as a result of runoff and/or spray drift. Aerobic soil metabolismis the main degradative process for dicamba. A single obkerved half-life for dicambawas six days, with formation ofthe intermediatenon-persist&nt degradate dichlorosalicylic acid (DCSA) at a maximum concentrationof 17.5%. ~CSA 

### degraded at roughly the same rate as dicamba; the final metaboliteswere carbon and microbial biomass. Dicamba is stableto abiotic hydrolysis at all pH's and 

# , photodegrades slowly in water and on soil. Dicamba is more persistent under anaerobic soil :water systemsin the laboratory, half-life of 141 days. The major degradateunder anaerobic conditionswas DCS$:kh was persistent, comprising> 60% ofthe applied after 365 days of anaerobic No other anaerobic degradateswere present at 

### > 10% during the incubation. acceptable data for the aerobic aquatic metabolismof dicamba; indicates that dicamba degades more rapidly in aquatic systems Dicamba is very soluble (6,100 ppm) and very mobile (&, = 

### 13.4)in the Because dicambais not persistent under aerobic conditions,very little is leach to groundwater. Any dicamba reaching anaerobic ground water would be somewhatpersistent (due to its anaerobic half-life of 141 days); any ground water would be expectedto persist as well. Results from two acceptable field dissipation studies conducted with of dicamba, indicatedthat dicamba dissipated with a half-life range The DCSA was the major degadate in both studies. Both, dicamba

### (DCSA) were found in soil segmentsdeeper than 10cm. Dicamba is not expectedto bioaccumulate in aquatic organismsbecause it is an anion at environmentalpHs (pKa = 

### 1.9). Surface Water: PRZM-EXAMS simulationswere conducted for the use on teff grown for seed, grain, and hay to calculate peak, 21-day average, and 60-day average EECs for parent dicarnbia and its degradate dichlorosalicylicacid (DCSA). A total toxic residues approach was used to determine the exposure. Dicamba and DCSA were 

### run separately using PRZWEXAMS and then their daily EECs spanning over a 30 year period were combined using a residue summation approach. Then the goth percentile was taken to determine the peak, 21-day, and 60 day EECs. SelectedPRZMIEXAMS modeling inputs are shown in. The input and output files for these runs are in Appendix A. Table 1. Surfacewater exposure inputs for 

### PRZMEXAMS for Dicamba (application date 05/15/2010) MODEL INPUT

VARIABLE Application rate (kg ailhectare) Number of appl./season Interval between appl. (d) Application Method Scenario modeled Henry's Law Constant (atm m3/mol) Molecular Weight (g/mol) Solubility @ 25°C (mg/L) Vapor Pressure (torr)

%C (mL/g)
Aerobic Soil Metabolic Half-life (days) Anaerobic Soil Metabolic Half-life (days) Is the pesticide wetted-in? Spray Drift Fraction Application Efficiency Aerobic Aquatic Metabolic Half-life (days)

Anaerobic Aquatic Metabolic Half-life (days) Hydrolysis (pH 7) half-life (days) INPUT VALUE 0.3 1

1 Not Applicable Ground ORgrassseedSTD 1.6 x lo-'

22 1 6100 3.41x 13.4 (average)
18
18
No 0.01 0.99

12

423

0 SOURCE and COMMENTS Proposed Emergency Exemption (0.28 lb a.i./A) Proposed Emergency Exemption Proposed Emergency Exemption Proposed Emergency Exemption Closest scenario available Estimated (VP x MW)/(760todl atm 

## * solubility) SANDOZE Safety Data Sheet (Nov, 1989). SANDOZE Safety Data Sheet (Nov, 1989). SANDOZE Safety Data Sheet (Nov, 1989). MRID# 42774101 ;Input parameters guideline (1

0/22/2009). MRID # 43245207; (6d x 3) lnput parameters guideline (10/22/2009). MRID # 43245207; (6d 

### x 3) lnput parameters guideline (1

0/22/2009). EPA Reg. No. 5905-564 Input guideline, 2009 Input guideline, 2009 No acceptable aerobic aquatic metabolism data were available, therefore 2x the aerobic soil metabolism half-life (identified above) was used per guidance (Input guideline, 2009). MRID# 43245208. Input Parameter Guidance 2009. (141 x 3 =423) Stable. IvlRID# 40547902MRID 42774102. Input Parameter Guidance 2009; Adjusted half-life to represent sun intensity and 12hours of sunlightper day. 3 8.1 day value represented co~tinuous sun exposure at an intensity of 1.38times natural sbnlight. Degradate not present.Aquatic Photolysis Halflife (days)

I 

### Table2. Surface water exposure inputs for 

### PRZMEXAMS for DCSA (application date 05/15/2010) I 105

I SOURCE and COMMENTS I Proposed Emergency Exemption (0.26 lb a.i./A) 

# ~

I I I Proposed Emergency Exemption I , I Proposed Emergency Exemption , Closest scenario available I MODEL INPUT

VARIABLE Applicationrate (kg ailhectare) Number of appl./season Interval between appl. (d) Scenario modeled INPUT VALUE 0.29

1 Not Applicable ORgrassseedSTD

P Henry's Law Constant (atm m3/mol) Molecular Weight (gmol) Solubility @ 25OC (m@) Vapor Pressure (torr) 

### - 

### KO, (mL/g) Aerobic SailMetabolic Half-life (days) Anaerobic Soil Metabolic Half-life (days) Is the pesticide wetted-in? Spray Drift Fraction Application Efficiency Aerobic Aquatic Metabolic Half-life (days)

Anaerobic Aquatic Metabolic Half-life (days) Hydrolysis (pH 7)half-life (days)Aquatic Photolysis Halflife (days)



### *(degradatemolecular

I 

## Effect Characterization 1.6x
207 21 12 3.4 1

### x 1208 (average) 24.6
24.6
No 0.01 0.99 16.4

0
0
105



### weight)/(parent Estimated for dicamba and used for DCSA (VP x MW)/(760torrll atm 

## * solubility) I Product Chemistry I I 

### MRID 43095301
I For Dicamba. SANDOZE Safety Data Sheet (NO+,1989). MRID# 4309530; Input parameters guideline (10/~2/2009). MRID # 43245207; (8.2 d 

### x 3) lnput parameters +idelhe (10/22/2009). MRID # 43245207; (8.2 d x 3) lnput parameters (1

0/22/2009). EPA Reg. 

### No. 5905-564 Input guideline, 2009 Input guideline, 2009 No acceptable aerobic aquatic metabolism data available, therefore 2x the aerobic soilmetabolisni (identified above) was used per guidance (Input 2009). Stable. MRID# 43245208. Input Parameter Guidance 2009. glideline

were half-life glideline,

Stable.MRID# 43245208
No informationfor the degradate; therefore, used dicamba:MRID 42774102. Input Parameter Guidance value for 2009. Adjusted half-life to represent sun intensity and 12 hours of sunlightper day. 38.1 day value represe ted continuous sun exposure at an intensity of 1.38t' es natural sunlight. 

### molecular weight) 

### x application rate 

# 1

### The Agency does not routinely include, in its risk assessments,an evaluation ofmixtures of active ingredients, either those mixtures ofmultiple active ingredients in product formulations or those in the applicator's tank. In the case of the product formulationsof active ingredients (that is, a registered product containingmore than one active ingredient), each active ingredient is subjectto an individual risk assessment for regulatory decision regarding the active ingredient on a particular use site. If effects data are available for a formulated product containingmore than one active ingredient, they may be used qualitatively or quantitatively in accordance with the Agency's Overview Document and the Services' Evaluation Memorandum (U.S., EPA 2004; USFWS/NMFS 2004). Latigo is a registered product that contains multiple active ingredients. Analysis ofthe available acute oral mammalian LD50 data (and available open literaturefor 

### dicamba) for multiple active ingredient products relative to the single active ingredient is provided below. The results ofthis analysis showthat an assessmentbased on the toxicity ofthe single active ingredients of Latigo is appropriate
The toxicity ofthe mixture of 2,4-D and dicamba as compared to the technical grade active ingredient (TGAI) toxicity was evaluatedto determinewhether the formulated products are more toxic than the TGAI. Limited information has been submitted regarding the toxicity ofthe Latigo formulation or of other mixtures of 2,4-D and dicamba. However, mammalianrat acute oral toxicity data is available on a mixture of 12.4%dicamba with 35.7% 2,4-D salt. This product had LD50formulationvalues (MRID 44948003) of 1889mglkg for males and 1180mglkg-bw for females which is of intermediate toxicity compared to the two technical active ingredients alone. The dicamba technical LD50 value exhibits lower toxicity (MRID 00078444) with an LD50of 2740 mglkg-bw. The 2,4-D technical LDSo has greater toxicity to rats (MRID 00101605) with an LD50of 639 mgkg. No confidence intervals were able to be calculated for any of these studies. When the mixture formulationis adjusted for toxicity ofthe active ingredient, the toxicity for 2,4-D to female rats in that formulationis 421.26 mg a.i.kgbw which is relatively close to the reported 2,4-D technical LD50toxicity indicating that these products do not appear to be synergists. 2,4-D acid and dicamba acid have the same molecular weight, so no conversion from a mass-based toxicity to a molar based toxicity is necessary. The rest ofthis assessmentwill focus solely on the dicamba acid part ofthe mixture.
Acute and chronicrisk was based on the most sensitive species forterrestrial and aquatic organisms. The acute and chronic toxicity values for the most sensitive terrestrial and aquatic organisms are presented in Table 3. 

### No chronic toxicity data is availablefor any fish or aquatic invertebratetaxa. Toxicity ofthe major degradate,DCSA, is unknown. However, DCSA does appear to have comparatively similar chemical structureto dicarnba. Therefore, for this assessment,EFED will assume that DCSA residues have equal toxicity to parent dicamba.

### Table 

### 3. Toxicity values for most-sensitive aquatic and terrestrial species to dicamba AQUATIC ORGANISMS I

Rainbow trout (Oncorhynchur mykiss) 

# 1 000253!/l0l/N~ (TGAI $6.6%) Chronic Endpoints (mg afi) Species

Sheepshead Minnow (Cyprinodon variegatus) Acute Endpoints (mg afil
96 

### hr LC50 =28
96 hr LC5, >I80

Water Flea (Daphnia magna) Grass Shrimp (Palaemonetes pugio) 

### ND

Duckweed (Lemna gibba)

I TERRESTRIAL ORGANISMS 

# I 48 hr EC50 

### > 100
96 hr EC50 >

Blue-green algae (Anabaena ji'os-aquae.) 40098001/N~ (TGAI 88%)

I

14-d IC50 > 3.25 ,

ND
ND

5-d IC50 = 0.061 40094602)FJD (TGAI 88%) 00034q02m (TGAI f46.2%)
I 14-d NOAEC =0.20

Number (ac~.te/chronic)
Bobwhite (Colinusvirginianus) Mallard duck (Anas platyrhynchos) --chronicendpoint only

Rat 5-d NOAEC = 0.005

MRD

Honeybee (Apis rnellijera) Terrestrial Plants

Monocot (Onion) 

# I ECz5/NOAEC = 0.0041 

# I ECz5/NOAEC = 0.062/ 

# I i 4277411
42774109 (TGAI 89.5%)

1

Chronic Endpoints Species
Acute Oral LD50 = 188 mg ailkg-bw Acute DietaryLC5, > 10,000mg aikg-diet Acute Oral LDS0 =2740 mg/kg Acute Dietary LOAEL = 3111)

Dicot (Soybean)

NA =Not Applicable 1(TGAI 89.5%)

Acute Endpoints



### --- I LD50

### > 90.65 pghee 

# I NA Non-1istedIListed species



# 'Based on reduction in hatchability at 1600mg/kg '~ecreased pup weight was seen at the LOAEL of 136mg/kg/day = mdkgl

NOAEL =45 mg /kg/da?

SeedlingEmergence
Ec25m0AEC = 0.0027 1<0.002lb/A Seedling Emergence 0003I 42918d01,000253911 438 1400b (TGAI 86.9%)
I

5935 (TGAI)
vegetative Vigor EC~~~OAEC = 0.00651 <0.004 1bIA Vegetative Vigor 0

I I I3078444, 42774104143 137101 (TGAI)

## Risk Summary Aquatic Organisms:


### EECs and RQs for aquatic organisms are presented in Table 4. No acute RQ values exceeded any LOCs for freshwater and estuarinelmarinefish and invertebratesor LOCs for aquatic plants. No chronic data for fish or invertebrates was available, therefore EFED will assume that there ispotential for chronic risk to aquatic organisms.



# 1 I I Invertebrate

. 

# 1 0.0000044 

## ( NA 

# 1 Table 

### 4. EECs and 

### RQs for Ground Applications of Dicamba to Teff. EEC 

### (PP~)

(Palaemonetes pugio) Plant -

### vascular (duckweed)

Invertebrate chronic RQ =

### 21-d 

### EECIchronicNOAEC

0.441 1 

### 0.3 19 1 

### NA I 

### Estuarinelmarine I I I Taxa 

### FreshwaterFish EstuarinelmarineFish (Sheepshead minnow) Freshwater Invertebrate (Daphniamagna) Peak 0.441 

### 0.441 0.44 1

0.441



### Terrestrialorganisms: 

### 0.002

RQs and EECs for birds and mammals are provided in the TREX tables in Table 5 and Appendix B. 

### Maximum dietary-based EECs on potential food items range from 4.2 ppm to 67.2 ppm. The acute Level of Concern (LOC of 0.5) for potential effects to non-listed animals from acute exposures is exceeded for small birds on short grasses. The acute listed species dose-based LOC (0.1) is exceeded for smallbirds consuming tall grasses, broadleaf plants and small insects and medium birds consuming short grasses, tall grasses,broadleaf plants and small insects. As toxicity information is not available for land-phase amphibians and reptiles, birds are used as surrogates for these taxa, therefore acute dose-based risk is also expected for these organisms. Avian dietary based RQ values did not exceed any LOCs. 21 

### -day avg.

NA



### --- NA 

### 0.3 19 RQ

NA



### Acute RQ =

### Peak EECIacutetoxicityvalue; Fish chronic RQ = 

### 60-d EECIchronicNOAEC; NA



### Mammalian dietarybased RQ 

### values exceeded the acute listed LOC (0.1) for short grass, tall grass, broadleaf plants and small insects. Small and medium sized mammals had chronic dose-based RQ values that exceeded the chronic LOC (1.O) for potential effects to non-listed and listed animals from chronic dietary exposureto short grass. 60-day avg. 0.222 0.222 NA acute 0.000016
-- 

### 0.0000024 0.0000044 chronic NA NA NA

NA 

### Plant -

### nonvascular (AnabaenaJlos-aquae) 0.087 NA

# 1 Acute: 

# I Table 5. LOCs Exceeded For Acute and Chronic Risk to Birds and Mammals from Dicamba Ground Application to Teff in Oregon

food 

### Taxa RQ



### 0.57 

## I insects

- 100 g 

## I Shortgrasses, tall grasses, broadleaf 

# 1 0.12-0.25 weight Dose-based

Shortgrasses Birds

1 I I 

# I

Mammals



### Dicamba is practically non-toxicto beneficial insects (honeybee acute contact LDSo

### > 90.65 yg 

### aihee). This acute contact LDS0 value was converted to a body weight vblue using 0.128 g as the body weight of a bee. The extrapolated acute contact toxicity alue for terrestrial invertebrates is 708 ppm.2 Risk to insects were evaluatedby comp ing dicamba toxicity, as determined in the submittedhoneybee acute contact study, 'th the residue levels horn dicambause on small and large insects generated as dietary-b sed EECs for birds and mammals using 

### T-REX. Comparisonsof the EECs for dicam a uses and the extrapolated acute toxicity are presented in Table 

### 6. Although the Agenc does

listed species ofterrestrial insects will be assumed. 

# i

not have an official LOC for terrestrial invertebrates, an interim acute endangeredspecies LOC of 0.05 is used for terrestrial invertebrates in endangered species assessment The small insects value calculatedhom T-REX barely exceeds this value, therefore ris

# 1
to

I 

### Table 

### 6. Comparisonsof Small and Large Insect EECs from Ground ~~~lic~tion of Dicamba to the Extrapolated Acute Contact Honeybee Concentration I 

### Dietary


# ~ 20 g



## Chronic:

Mammals 

# 1 15-35 g 

# I Short grass 

## 1 1.11-1.30 

# 1

- Application Rate Dietary Item EEC (mg/kg-diet) Teff 

### - 0.28 lb aUAJ .Tall grasses, Broadleafplants & small 

# I plants, & small insects Shortgrass, tall grass,broadleaf plants 5-1000g 

# / & small insects
Al110.15

I I I I I

*basedon extrapolated acutecontact value of 708 ppm. I 

### 0.26-0.32

Acute LOC = 0.1 (listed species) and 0.5 (non-listed species); chronic LOC = 1.0



### TerrPlant (Version 1.2.2) is used to calculateEECs for non-target plant species i dry and semi-aquatic areas. Parameter values for application rate, drift
found in Appendix C. incorporation depth are based upon the use and related applicationmethod and c$ be

RQs were exceeded for listed and non-listed monocots and dicots on both dry and semiaquatic land as well as through spray-drift except that non-listed monocot RQ values did ,



### - LD50honeybee - 

### 90.65 ~g 

### - 708 

### ppm 2 

### Ex@a~olated LD50 temza,In sect 

### - whomy bee 

### 0.128 g All O.O1 I 0.110-0.22

### not exceed LOCs (1.O) on 

### dry land. As a broadleafherbicide, dicambawould be expected to have greatest risk to dicots, which greatly exceeded the LOC. Because the NOAEC values are inequalities (less than the lowest treatment level tested) and no ECoj values were generated, risk to listed speciesmay actuallybe higher than these values indicate.

When there are exceedances for any of the taxa, a buffer is determined using AgDRIFT. AgDrift is a peer-reviewed model that predicts the amount of residue deposition at distances from the edge of the treated field. It is EFED policy for AgDrift model inputs that for pesticides that contain spray application labeling that do not use specific language on nozzle size, analysts will use the very fine to finenozzle spray size as input for the model. Fine to medium/coarse size was used for input into the AgDrift model and ground application was modeled.

Table 7. RQ values for plants in dry and semi-aquatic areas exposed to Dicambathrough runoff andlor spray drift.*



### The most sensitive endpoint ofall of the species assessed was for the dicot plant (soybean). Therefore, the EC25 for the terrestrial seedling emergence soybean study (0.0027 lb a.i./A) was used in AgDRIFT to determine the buffer. The maximum application rate of 0.31 lb ai/A was used. A fraction of applied was determined using the EC2jdividedby the application rate in order to model the distance necessary from the edge of the field before the concentration of dicamba on the surfacewould be at the EC2j concentrationfor the most sensitive terrestrial plant (soybean). For ground application from a point source, a distance of 76 feet off site is required before the concentrationis at the EC25 for the terrestrial plant seedling emergence soybean study. Plant Type

Monocot Monocot

Dicot Dicot



### The 2006 

### RED recorded thirty-five ecological incidents attributedto dicamba use having been recorded in the Ecological Incident Information System (EIIS) as ofJunel, 2005. Since the RED, two additional incidentshave been reported. In 2006, in St.Landry County, LA, 1500 acres of soybean were damaged by a combinationof glyphosate,dicamba and 2,4-D. The type of injury was not reported. This incidentwas classified as probable for dicamba and 2,4-D and possible for glyphosate and the incidentwas considered as an intentional misuse. In 2007, in Lancaster County, PA, 4 rabbits were killed after a homeowner applied product with MCPP, Dicamba, and 2-4 D ingredientsto the house lawn. This incidentwas classified aspossible for all three active ingredients and the legality was undetermined. The earlier incidents reported include terrestrial, plant, and aquatic impacts. 19 ofthe incidents involve 2,4-D in addition to dicamba and sometimes other active ingredients. Although the database lists a terrestrial mammalian incident in Utah where dicamba was

*If RQ > 

### 1.O, the LOC is exceeded, resulting in potential for risk to that plant group. Listed Status

non-listed listed non-listed listed Dry 0.97 

### 1

.OO 22.22 30.00 Semi-Aquatic 8.23 8.50 188.89 255.00 Spray Drift 6.25 6.67 3.70 5.00

### applied,the database states that dicarnba is "unlikely"to have caused the incident. Impacts to plants included a wide range of crops (soybeans, corn, wheat) as well as non-agricultural applications. The specific impacts varied from browning and plant damage to mortality of all plants within the treated area. Aquatic impacts consist oftwo fish kill incidents associated with agricultural and residential turf application. Therefore, acute adverse risk from dicarnba application to teff is expected for reptiles, amphibians,birds, and non-target plants (especially dicots). Adverse risk from acyte dietary-based exposure to mammals may also occur. Chronic exposure to marnmdls may also result in adverse risk from dicamba use on teff. Due to a lack of chronictoxidity data, potential risk exists for chronic effectsto fish and aquatic invertebrates. 

### A li$tof Federal endangered and threatened species is shownin 

### E.

## Appendix A. Surface

## Water EECs from 

## PRZMIEXAMS

Outputfrom Dicamba run: stored as Dicamba Teff.out Chemical: Dicamba PRZM environment: 0RgrassseedSTD.txt modified Tueday, 26 August 2008 at 06:16:42 EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:08 Metfile: w24232.dvf modified Tueday, 26 August 2008 at 06:15:54 Water segment concentrations (ppb)

Year 1961 1962 Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.155 0.1478 0.1213 0.07595 0.05662 0.01481 0.1551 0.1484 0.1239 0.07937 0.05852 0.01542 0.1551 0.1467 0.1174 0.07417 0.05505 0.01452 0.1551 0.1477 0.1209 0.07618 0.0557 0.0146 0.1551 0.1482 0.1229 0.09117 0.0685 0.01807 0.1551 0.1475 0.12 0.07458 0.05453 0.01424 0.1551 0.1476 0.1206 0.07321 0.05282 0.01356 0.1926 0.1834 0.1596 0.1062 0.07803 0.02033 0.3189 0.2965 0.2295 0.139 0.1255 0.03631 0.1553 0.1477 0.1202 0.07261 0.05238 0.01402 0.1551 0.1479 0.1219 0.08424 0.06345 0.01679 0.7646 0.7254 0.5832 0.364 0.2653 0.0687 0.1553 0.1473 0.1188 0.07396 0.05386 0.01447 0.155 0.1481 0.1224 0.07647 0.05596 0.01456 0.1551 0.1476 0.1205 0.07655 0.05616 0.01475 0.1551 0.1479 0.1217 0.07922 0.05864 0.01547 0.3004 0.2873 0.2388 0.1491 0.1092 0.02844 0.1551 0.1472 0.1187 0.07097 0.06062 0.01695 0.1551 0.1468 0.1173 0.07186 0.05202 0.01378 0.1551 0.1478 0.1213 0.09132 0.06909 0.01836 0.1919 0.1848 0.1466 0.1207 0.09271 0.02462 0.1551 0.1474 0.1195 0.07184 0.05212 0.01365 0.155 0.1467 0.1172 0.076 0.05709 0.01502Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 1.492 1.419 1.091 0.6227 0.4552 0.122 0.0645161290322581 0.7646 0.7254 0.5832 0.364 0.2653 0.0687 0.0967741935483871 0.3189 0.2965 0.2388 0 .I49 0.1255 0.03631 0.129032258064516 0.3004 0.2873 0.2295 0.139 0.109 0.03111 0.161290322580645 0.2568 0.2383 0.1766 0.1207 0.09704 0.02916 0.193548387096774 0.2165 0.2022 0.1596 0.1062 0.09452 0.02844 0.225806451612903 0.1926 0.1848 0.1538 0.1025 0.09271 0.02462 0.258064516129032 0.1919 0.1834 0.1466 0.09944 0.07803 0.02059 0.290322580645161 0.1553 0.1484 0.1271 0.0986 0.07793 0.02033 0.32258064516129 0.1553 0.1482 0.123 9 0.09132 0.06909 0.01836 0.354838709677419 0.1553 0.1481 0.1229 0.09117 0.0685 0.01807 I 0.387096774193548 0.1551 0.148 0.1224 0.08424 0.01695 0.419354838709677 0.1551 0.1479 0.1221 0.08005 0.06062 0.01679 0.451612903225806 0.1551 0.1479 0.1219 0.07937 0.05864 0.01547 0.483870967741936 0.1551 0.1478 0.1219 0.07922 0.05852 0.01542 0.516129032258065 0.1551 0.1478 0.1217 0.07829 0.05784 0.01524 0.548387096774194 0.1551 0.1478 0.1213 0.07655 0.05723 0.01502 0.580645161290323 0.1551 0.1477 0.1213 0.07647 0.05709 0.0149 0.612903225806452 0.1551 0.1477 0.1209 0.07618 0.05662 0.01481 0.645161290322581 0.1551 0.1476 0.1206 0.01475 0.67741935483871 0.1551 0.1476 0.1205 0.07595 0.05596 0.0146 0.709677419354839 0.1551 0.1475 0.1202 0.07458 0.0557 0.014560.1 0.31705 0.29558 0.23787 0.14809 0.12387 0.03579 Average of yearly averages: 0.023303 Inputs generated by pe5.pl 

## - Novemeber 2006
Data used for this run: Output File: Dicamba Teff Metf ile: w24232.dvf PRZM scenario: 0RgrassseedSTD.txt EXAMS environment file: pond298.exv Chemical Name: Dicamba Description Variable Name Value Units Comments Molecular weight mwt 221 g/mol Henry's Law Const. henry 1.6E-9 atm-mA3/mol Vapor Pressure vapr 3.413-5 torr Solubility sol 6100 mg/L Kd Kd m9/L Koc Koc 13.4 mg/L Photolysis half-life kdp 105 days Half-life Aerobic Aquatic Metabolism kbacw 12 days Halfife Anaerobic Aquatic Metabolism kbacs 423 days Halfife Aerobic Soil Metabolism asm 18 days Halfife Hydrolysis: pH 5 0 days Half-life Hydrolysis: pH 7 0 days Half-life Hydrolysis: pH 9 0 days Half-life Method : CAM 2 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 0.32 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-5 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF total(average of entire run) none, monthly or

### Output from 

### DCSA run: stored as DCSA Teff-out Chemical: DCSA PRZM environment: 0RgrassseedSTD.txt modified Tueday, 26 August 2008 at 06:16:42 EXAMS environment: pond298.exv modified Tueday, 26 August 200b at 06:14:08 1 Metfile: w24232.dvf modified Tueday, 26 August 2008 at 06:15:5k Water segment concentrations (ppb) I

Year 1961 Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.1446 0.1337 0.09963 0.05928 0.0454 0.01542 I 0.1498 0.1392 0.106 0.06565 0.05104 0.021015 0.151 0.1391 0.1028 0.06347 0.04976 0.021812 0.1517 0.1407 0.106 0.06552 0.05084 0.021613 0.1508 0.1401 0.1064 0.06751 0.05238 0.02157 0.1509 0.1397 0.1048 0.06407 0.0497 0.02088 0.151 0.14 0.1052 0.06336 0.04866 0.0201 0.1503 0.1392 0.1107 0.07087 0.05498 0.02425 0.1523 0.1403 0.1033 0.07926 0.06698 0.03092 0.1554 0.1441 0.1089 0.06636 0.05141 0.02406 0.1518 0.1409 0.1067 0.07014 0.05524 0.02602 0.2245 0.2077 0.1571 0.09743 0.07538 0.0308 0.1538 0.1423 0.1067 0.06595 0.05126 0.02345 0.151 0.1402 0.1062 0.06514 0.05054 0.1512 0.1401 0.1053 0.06528 0.05071 0.02175 0.1515 0.1406 0.1064 0.06694 0.05228 0.02203 0.1619 0.1506 0.1146 0.07022 0.05451 0.0227 0.151 0.1395 0.1038 0.06199 0.04922 0.1513 0.1397 0.1036 0.06289 0.04849 0.02504 0.1539 0.1429 0.1084 0.07285 0.05743 0.02538 

### I 0.1517 0.1407 0.1063 0.08363 0.06645 0.02792 0.1535 0.1422 0.1068 0.06454 0.05012 0.02229 I 0.1503 0.1386 0.1025 0.06438 0.05302 I 0.02331 0.1521 0.1411 0.1068 0.08218 0.06578 0.02769 

## 1 0.295 0.2796 0.2065 0.1407 0.1129 0.04652 0.1603 0.1488 0.1129 0.07373 0.06107 0.03083d'w w w 0 0 rl rl

in N rlmom wmwm In N TI' N 0 0

rl In TI' In 0 00.1 0.18008 0.165 0.11973 0.083485 0.074324 Average of yearly averages: Inputs generated by pe5.pl - Novemeber 2006
Data used for this run: Output File: DCSA Teff Metf ile: w24232.dvf PRZM scenario: 0RgrassseedSTD.txt EXAMS environment file: pond298.exv Chemical Name: DCSA Description Variable Name Value Units Comments Molecular weight mwt 207 g/mol Henry's Law Const. henry 1.6E-9 atm-mA3/mol Vapor Pressure vapr 3.413-5 torr Solubility sol 2112 mg/L Kd Kd mg/L Koc Koc 1208 mg/L Photolysis half-life kdp 105 days Half-life Aerobic Aquatic Metabolism kbacw 16.4 days Halfife Anaerobic Aquatic Metabolism kbacs 0 days Halfife Aerobic Soil Metabolism asm 24.6 days Halfife Hydrolysis: pH 5 0 days Half-life Hydrolysis: pH 7 0 days Half-life Hydrolysis: pH 9 0 days Half-life Method : CAM 2 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 0.29 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to Application Date Date 15-5 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0:5 Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF none, monthly or total(average of entire run) 

### Example of a portion of the Residue Summationto determine Total Toxic ~dsidues for Dicamba and DCSA

Year MaxPeak 4-day Max 14day Max 21 day Max 30 day Max 60 day Max 90 day Annual 

### 1790th % (ppm)

90th % (ppb) 1 0.4413 0.34853286 0.31943048 vlax Peak 4-day Max14day Max21day 0.28322933 0.22169233 Max 30 day Max 60 day 0.175049889 Max 90 day Average Annual 0.09314 Annual

0.00006

## Appendix 

## B. T-REX Input and 

## Output

TREX MODEL INPUTS These values mll be used m thecakulatton of exposureestmatesfor follar,granula-, llquldandlor seed appliations of pestic~des.

Use: Produd name and form: X A.I. (leadingzero must be enteredfol formulations 4% a.i.) Application Rate (IbslA): Half-life(days): Application Interval(days)'

What bodyweight range is assessed (grams)?

LC50 (mglkgdiet Reported Chronic Endpoin Medium Laqe



### Summary of Risk Quotient Calculations Based on Upper Bound Kenaga 

### EETs I I I Birds Mammals

Note: Sounes of wildllfe d~et are assumedto be availablefor lessthan one vearforthls model. Endpoints 100 

### I 35 1000

Table X. Upper Bound Kenaga,Acute Avian Dose-Based Risk Quotients
I I000

Size Class (grams) Adjusted LD50 EECs and RQs
Short Grass Tall Grass 

# ~ Granivore

I BroadleafPlants1 Insects Fruits/Pods/ Large InsectsTable X. Upper Bound Kenaga, SubacuteAvian Dietary Based Risk Quotients 20 100
1000 RQ

0.57 0.25
0.08



# I 135.44 172.42
243.55

EECs and RQs I I I 

# 1

Short Grass

Size class not used for dietary risk quotients EEC

76.53 43.64
19.54 EEC

35.08 20.00
8.96

LC50 10000

Table 

### X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients Tall Grass RQ

0.26 0.12
0.04

EEC 67.20

Table X. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients EECs and RQs I I I I Broadleaf

Plants/ Small Insects

NOAEC (PP~) 800 EEC

43.05 24.55
10.99

Fruits/Pods/ Seeds/ Large Insects

RQ 0.01

Size class not used for dietaryrisk quotients EECs and RQs

Size Class djusted 

# IDSO
(grams) RQ

0.32 0.14
0.05

EEC 30.80

Short Grass

Short Grass RQ 0.00

EEC 67.20 EEC

4.78 2.73
1.22

RQ 0.08 Tall Grass

Tall Grass RQ

0.04 0.02
0.01 EEC

1.06 0.61
0.27

EEC 37.80

EEC 30.80 RQ

0.01 0.00
0.00

RQ 0.04 Broadleaf Plants/ Small Insects

Broadleaf Plants1

Small Insects RQ 0.00

EEC 37.80 FruitsIPodsl Seeds/ Large Insects
RQ 0.05 EEC 4.20

FruitsIPodsl Seeds, Large Insects EEC 4.20

RQ 0.01

Granivore RQ 0.00Size class not used for dietary risk quotients

Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk

Size class not used for dietaryrisk quotients Quotients

NOAEC (PPm)

450

Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients EECs and RQs I I I EECs and RQs

1- 

### Size

(grams) Adjusted NOAEL FruitsIPodsl Seeds1 Large Insects

EEC 4.20 Broadleaf

Plants1 Small Insects Short Grass

Short Grass RQ 0.01 ,EEC 37.80 Tall Grass
EEC 67.20 RQ 0.08 EEC 30.80 RQ 0.15

Tall Grass RQ 0.07

Broadleaf Plants1 Insects Fruits/Pods/ Large Insects Cjranivore



### ,

## Appendix 

## C. TerrPlant Input and Output TerrPlant v. 1.2.2 Green values signify user inputs (Tables 1,2 and 4). lnput and output guidance is in popups indicated by red arrows.
Tab& 

### 3 ,tEberntcza3

### gdentfty. Chemical Name PC code Use Application Method

Application Form Solubility inWater (PP~)

TaMe 

### 2- 1npT.rt

### p;lr;ur~efeas, mdt6 derive 

### 'EECs.

, , , Dicamba 29801 TeR Foliar Liquid
6100

Input Parameter Application Rate

Incorporation Runoff Fraction

Drift Fraction


### Table 3, 

## EEGS frpk~immba, W@ 

### in-, Description Runoff to dry areas Runoffto semi-aquatic areas Spray drift Total for dry areas Total for semi-aquatic areas

Ta4lW. Plapfsuwivaland

### graWkk@&a 

### used for 

### RQJlefJveticfa. 

### Wits 

## arein 

# . Symbol A I R D

Plant type

Monocot



### TaMe 

### 5. RQgaltce. 

### for 

### plan& in

### dryaedsemiaaq~atic 

### ~e~~x~~~edko~i~brr~~otc~ run^@ andrur$pray 

### d&W Equation (A/I)*R (A.I)*R*I0 A* D ((AH)*R)+(A*D) ((AII)*R*IO)+(A*D)

Plant Type

Monocot Monocot

Dicot Dicot Value 1 I 0.05 0.01

EEC 0.05 0.5 0.01 0.06 0.51

Dicot 0.0027 Units

none none none

Seedling Emergence

*If RQ > 1.0, the 

### LOC is exceeded, resulting in potential for risk to that plant group. Listed Status

non-listed listed non-listed

listed EC25 0.062 Vegetative Vigor NOAEC

0.06 EC25 0.0016

Dry 0.97 1

.OO 22.22 30.00 NOAEC 0.0015

Semi-Aquatic 8.23 8.50 188.89 255.00 Spray Drift 6.25 6.67 3.70 5.00

## Appendix D. AGDRIFT Output Ground; 

### fine to medium coarse droplet; High Boom

## Appendix E. LOCATES Output 

# Species in Countiesby 

# State and Taxa No species were excluded Minimum of 1Acre 

### All 

### Medium Types Reported Mammal, Marine mml, Bird, Amphibian, Reptile, Fish, Crustacean, Bivalve, Gastropod,Arachnid, Insect, Dicot, Monocot, Ferns, ConYcycds, Coral, Lichen 

### seed crops 

## - other field and grass, hay, other tame, grains 

## - other 

### (PR), haylage/grass silage/greenchop all Oregon 

### Bird 

## - Dicot Murrelet, Marbled Brachyramphus marmoratus manoratus Douglas Lane Polk Tillamook Owl, Northern Spotted Strix occidentalis caurina ssp. Benton Douglas Klamath Lake Lane Linn Marion Polk Tillamook Washington Yamhill Plover, Western Snowy Charadrius alexandrinus nivosus Douglas Lane Tillamook Milk-vetch, Applegate's Astragalus applegatei Klamath Popcornflower, Rough Plagiobothrys hirfus Douglas Checker-mallow, Nelson's Sidalcea nelsoniana Benton Linn Marion Polk Tillamook Washington Yamhill Daisy, Willamette Erigeron decumbens var. decumbens Benton Lane Linn Marion Polk Lomatium, Bradshaw's Lomatiumbradshawii 

### Dicot

Lupine, Kincaid's Lupinussulphureus (=oreganus ) Benton Douglas Lane Linn Polk Yamhill

Chub, Hutton Tui Gila bicolorssp. Lake Chub, Oregon Oregonichfhyscrameri Benton Lane Linn Marion Polk Dace, Foskett Speckled Rhinichthysosculus ssp. Lake Benton Lane Linn Marion Polk

### Fish 

# - Salmon, Chinook (Upper Willamette River) Oncorhynchus(=Salmo) tshawytscha Benton Douglas Lane Linn Marion Polk Tillamook Washington Sucker, Shortnose Chasmistes brevirostris

Sucker, Warner Catostomuswamerensis Lake Trout, Bull Salvelinus confluentus Yamhill Crook Salmon, Chum (Columbia River population) Oncorhynchus (=Salmo) keta Washington Salmon, Coho (Southern ORlSouthern CA Coast) Oncorhynchus (=Salmo) kisutch Douglas Klamath Steelhead, (Lower Columbia population) Oncorhynchus (=Salmo) mykiss Marion Washington Steelhead, (Middle Columbia population) Oncorhynchus(=Salmo) mykiss Crook Jefferson Steelhead, (Upper Willamette River population) Oncorhynchus (=Salmo) mykiss Benton Lane Linn Marion Polk Tillamook Washington Yamhill

, Deschutes Jefferson Klamath Lake Lane Linn Malheur Polk Yamhill Trout, Bull (Columbia River Population) Crook Deschutes Jefferson Klamath Lake Lane Linn

, Malheur Trout, Bull (Klamath River Population) Salvelinus confluentus Crook Deschutes Jefferson Klamath Lake Lane Linn Malheur Sucker, Lost River Deltistesluxatus
Klamath 

### Mammal

I Deer, ColumbianI White-tailed Odocoileusvirginiknus leucurus I Douglas 

### Insect Butterfly, Fenderk Blue lcaricia icarioidesfenderi

Benton Lane Polk Yamhill

Butterfly, Oregop Silverspot Speyeria zerene hippolyta Lane Tillamook Yamhill