Species % Purity Test Type Toxicity Affected Endpoints MRID No. Study author Classification Rat ( Charles River CD) 86.8 Subchronic feeding  13 weeks NOEL/ LOAEL = 500/ 1000 mg ai/ kg/ day body weight changes; liver effects 00128093 NA Acceptable Rat ( Charles River CD) 85.8 Developmental NOAEL/ LOAEL = 160/ 400 mg ai/ kg/ day NOAEL/ LOAEL= > 400/ mg ai/ kg/ day Maternal tox1 Developmental 00084024 NA Acceptable Rabbit ( New Zealand White) 90.5 Developmental NOAEL/ LOAEL = 30/ 150 mg ai/ kg/ day NOAEL/ LOAEL = 150/ 300 mg ai/ kg/ day Maternal tox2 Developmental 42429401 NA Acceptable Rat ( Sprague Dawley) 86.5 Reproduction NOAEL/ LOAEL = males  122/ 419 mg ai/ kg/ day; females  136/ 450 mg ai/ kg/ day NOAEL/ LOAEL = 45/ 136 mg ai/ kg/ day NOAEL/ LOAEL = 45/ 136 mg ai/ kg/ day Systemic tox3 Offspring tox Reproductive 43137101 Masters, 1993 Acceptableminimum 1 Maternal toxicity  Mortality, clinical signs of neurotoxicity, decreased body weight gain and food consumption. Developmental toxicity  No treatment related fetal gross, skeletal or visceral anomalies. 2 Maternal toxicity  Abortion, clinical signs of toxicity ( ataxia, rales, decreased motor activity), decreased body weight gain and food consumption. Developmental toxicity  Irregular ossification of internasal bones. 3Systemic toxicity  Clinical signs of neurotoxicity in dams during lactation ( tense/ stiff body tone, slow righting reflex), significantly increased relative liver to body weight ratios. Offspring toxicity  Significantly decreased pup growth. Developmental toxicity  Decreased pup growth, delayed sexual maturation in F1 males.

Insects, Acute Contact A honey bee acute contact study using the TGAI is required for dicamba acid because its foliar application treatment use will result in honey bee exposure. The acute contact LD 50 , using the honey bee, Apis mellifera, is an acute contact, single dose laboratory study designed to estimate the quantity of toxicant required to cause 50% mortality in a test population of bees. The 48 hour acute contact LD 50 for dicamba acid is > 90.65 µ g ae/ bee and it is, therefore, classified as practically non toxic to bees on a contact exposure basis and no label warning is needed. The guideline ( 141 1) is fulfilled ( MRID 00036935). 53 TABLE III. m. Non target Insects  Acute Contact.

Species % ai LD50 ( µ g ai/ bee) Toxicity Category MRID No. Author/ Year Study Classification Honey Bee ( Apis mellifera) Tech > 90.65 Practically non toxic 00036935 NA, 1975 Acceptable Insects, Residual Contact A honey bee toxicity of residues on foliage study is required on an end use product for any pesticide intended for outdoor application when the proposed use pattern indicates that honey bees may be exposed to the pesticide and when the formulation contains one or more active ingredients having an acute contact honey bee LD 50 which falls in the moderately toxic or highly toxic range. The purpose of this guideline study is to develop data on the residual toxicity to honey bees. Bee mortality determinations are made from bees exposed to treated foliage harvested at various time periods after treatment. No residue toxicity study was submitted by the registrant; therefore, the guideline ( 141 2) was not fulfilled; however, the acute contact honey bee LD 50 falls in the relatively non toxic range. In addition, no field tests for pollinators were submitted by the registrant ( guideline 141 5).

Terrestrial Plants Terrestrial Tier II studies are required for all low dose pesticides ( those with the maximum use rate of 0.5 lbs ai/ A or less) and for any pesticide showing a negative response equal to or greater than 25% in Tier I studies. Tier II terrestrial plant toxicity studies were conducted to establish the toxicity of dicamba to non target terrestrial plants. The recommendations for seedling emergence and vegetative vigor studies are for testing of ( 1) six species of at least four dicotyledonous families, one species of which is soybean ( Glycine max) and the second of which is a root crop, and ( 2) four species of at least two monocotyledonous families, one of which is corn ( Zea mays).

Results of Tier II toxicity studies with monocots and dicots indicate that seedling emergence and vegetative vigor are severely impacted by exposure to dicamba acid. The most sensitive monocot tested was onion ( EC 25 = 0.071 lb ai/ A  seed germination, radicle length; EC 25 = 0.0044 lb ai/ A  seedling emergence, shoot length; and EC 25 = 0.1507 lb ai/ A  vegetative vigor, shoot weight). The most sensitive dicot tested was soybean ( EC 25 = 0.036 lb ai/ A  seed germination, radicle length; EC 25 = 0.0027 lb ai/ A  seedling emergence, shoot length; and EC 25 = 0.0068 lb ai/ A  vegetative vigor, shoot length). Non lethal effects included brown leaf tips, necrosis, decrease in size, leaf curling, chlorosis, and stem tumors. However, the studies are not adequate because an NOAEC was not determined for the most sensitive endpoints in either study. Studies are need with the TEPs for all forms of dicamba. 54 TABLE III. n. Terrestrial Non target Plant Toxicity. a Species Seed Germination Seedling Emergence Vegetative Vigor Radicle length Shoot length Root weight Shoot length Shoot weight EC25 ( lb ai/ A) NOEC ( lb ai/ A) EC25 ( lb ai/ A) NOEC ( lb ai/ A) EC25 ( lbai/ A) NOEC ( lb ai/ A) EC25 ( lb ai/ A) NOEC ( lb ae/ A) EC25 ( lb ai/ A) NOEC ( lb ae/ A)

Monocots Corn 0.78 0.49 0.48 0.25 > 3.9 > 3.9 > 3.9 > 3.9 > 3.9 > 3.9 Oat 0.36 0.25 0.57 0.25 > 0.52 0.52 2.8 1.0 2.6 2.0 Onion 0.071 0.032 0.0044 < 0.032 0.062 < 0.13 0.81 0.26 0.15 0.13 Ryegrass 0.19 0.064 0.53 0.25 5.6 3.9 3.6 1.0 2.2 1.0 Dicots Cabbage 0.28 0.13 1.5 0.53 0.16 0.13 > 0.5 0.5 0.16 0.13 Cucumber 0.053 0.062 0.42 0.25 0.017 0.016 0.045 0.031 0.052 0.031 Lettuce 0.12 < 0.032 0.074 0.13 0.096 0.031 0.021 0.016 0.029 0.016 Turnip 0.20 0.064 0.044 0.016 0.0085 0.00054 0.043 0.0047 0.017 0.0091 Soybean 0.036 < 0.032 0.0027 < 0.0022 > 0.025 0.25 0.0068 < 0.0040 0.13 0.031 Tomato 0.031 < 0.035 0.054 0.032 0.13 0.064 0.029 0.016 0.020 0.016 aMRID 42846301, Study author: J. R. Hoberg, 1993. 55 IV. RISK CHARACTERIZATION Risk characterization provides the final step in the risk assessment process. In this step, exposure and effects characterization are integrated to provide an estimate of risk relative to established levels of concern ( LOC). The results are then interpreted for the risk manager through a risk description and synthesized into an overall conclusion.

A. Risk Estimation  Integration of Exposure and Effects Data A deterministic approach is used to evaluate the likelihood of adverse ecological effects to non target species. In this approach, risk quotients ( RQs) are calculated by dividing exposure estimates ( EECs) by ecotoxicity values for non target species, both acute and chronic.

RQ = EXPOSURE/ TOXICITY RQs are then compared to OPP's levels of concern ( LOCs). These LOCs are criteria used by OPP to indicate potential risk to non target organisms and the need to consider regulatory action. The criteria indicate that a pesticide used as directed has the potential to cause adverse effects on non target organisms. LOCs currently address the following risk presumption categories: ( 1) acute  potential for acute risk is high, regulatory action may be warranted in addition to restricted use classification ( 2) acute restricted use  the potential for acute risk is high, but this may be mitigated through restricted use classification ( 3) acute listed species  the potential for acute risk to listed species is high, regulatory action may be warranted, and ( 4) chronic risk  the potential for chronic risk is high, regulatory action may be warranted. Currently, EFED does not perform assessments for chronic risk to plants, acute or chronic risks to non target insects, or chronic risk from granular/ bait formulations to mammalian or avian species.

The ecotoxicity test values ( i. e., measurement endpoints) used in the acute and chronic risk quotients are derived from the results of required studies. Examples of ecotoxicity values derived from the results of short term laboratory studies that assess acute effects are: ( 1) LC50 ( fish) ( 2) LD50 ( birds and mammals) ( 3) EC50 ( aquatic plants and aquatic invertebrates) and ( 4) EC25 ( terrestrial plants). An example of a toxicity test effect level derived from the results of long term laboratory study that assesses chronic effects is: NOAEC ( birds, fish and aquatic invertebrates).

Risk presumptions, along with the corresponding RQs and LOCs are tabulated below: 56 TABLE IV. a. Risk Presumptions for Terrestrial Animals Risk Presumption RQ LOC Birds:

Acute Risk EEC1/ LC50 or LD50/ sqft2 or LD50/ day3 0.5 Acute Restricted Use EEC/ LC50 or LD50/ sqft or LD50/ day ( or LD50 < 50 mg/ kg) 0.2 Acute Listed Species EEC/ LC50 or LD50/ sqft or LD50/ day 0.1 Chronic Risk EEC/ NOAEC 1 Wild Mammals:

Acute Risk EEC/ LC50 or LD50/ sqft or LD50/ day 0.5 Acute Restricted Use EEC/ LC50 or LD50/ sqft or LD50/ day ( or LD50 < 50 mg/ kg) 0.2 Acute Listed Species EEC/ LC50 or LD50/ sqft or LD50/ day 0.1 Chronic Risk EEC/ NOAEC 1 1EEC= abbreviation for Estimated Environmental Concentration ( ppm) on avian/ mammalian food items mg/ ft mg of toxicant consumed/ day LD50 * wt. of bird LD50 * wt. of bird TABLE IV. b. Risk Presumptions for Aquatic Animals Risk Presumption RQ LOC Acute Risk EEC1/ LC50 or EC50 0.5 Acute Restricted Use EEC/ LC50 or EC50 0.1 Acute Listed Species EEC/ LC50 or EC50 0.05 Chronic Risk EEC/ MATC or NOAEC 1 1 EEC = ( ppm or ppb) in water TABLE IV. c. Risk Presumptions for Plants Risk Presumption RQ LOC Terrestrial and Semi Aquatic Plants:

Acute Risk EEC1/ EC25 1 Acute Listed Species EEC/ EC05 or NOAEC 1 Aquatic Plants:

Acute Risk EEC2/ EC50 1 Acute Listed Species EEC/ EC05 or NOAEC 1 1 EEC = lbs ai/ A 2 EEC = ( ppb/ ppm) in water 57 1. Non target Aquatic Animals and Plants Fish and Invertebrates No acute or chronic LOCs are exceeded for either freshwater or estuarine/ marine fish or aquatic invertebrates. However, the oyster toxicity test did not establish an EC 50 nor establish that it exceeds 100 ppm. An acute oyster study is needed to establish the toxicity of dicamba.

Aquatic Plants For dicamba acid runoff/ drift from ground and aerial spray application of pasture and sugarcane, the non listed Acute Risk LOC for the freshwater non vascular plant was exceeded ( Table IV. e.). For the pasture scenarios, the LOC was exceeded for the Texas scenario only. For sugarcane, the LOC was exceeded for both the Florida and Louisiana scenarios ( Appendix B). However, the non listed Acute Risk LOC for the freshwater non vascular plant was not exceeded in the asparagus, corn, sorghum, soybean, turf and wheat scenarios. There were no exceedances of the non listed freshwater vascular plant LOC. Likewise, the listed freshwater vascular plant LOC was not exceeded for any of the crop scenarios evaluated ( Table IV. e.). An assessment of listed risks to non vascular aquatic plants is not required since there are no listings of listed non vascular aquatic plants for dicamba at this time TABLE IV. e. Summarized Acute Aquatic Plant Risk Quotients for Dicamba Acid a, b, c, d Scenario Listed freshwater vascular Non listed Freshwater vascular Freshwater non vascular Michigan asparagus ( 0.5 lbs ae/ A) Ground app. < 1 Aerial app . < 1 < 1 < 1 < 1 < 1 Texas corn ( 0.75 lbs ae/ A) Ground app. < 1 Aerial app . < 1 < 1 < 1 < 1 < 1 Texas pasture ( 2.0 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 1.39** 1.38**

Texas sorghum ( 0.5 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 < 1 < 1 Mississippi soybean ( 2.0 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 < 1 < 1 Florida sugarcane ( 2.8 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 2.79** 2.72**

Pennsylvania turf ( 2.0 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 < 1 < 1 North Dakota wheat ( 1.0 lbs ae/ A) Ground app. < 1 Aerial app. < 1 < 1 < 1 < 1 < 1 a Detailed calculations of aerial and ground spray PRZM 3.12/ EXAMS 2.98 modeling are provided in Appendix B. b* indicates an exceedance of Listed Species Level of Concern ( LOC); RQ > 1.0. c** indicates an exceedance of Acute Risk Level of Concern ( LOC); RQ> 1.0. d Listed acute toxicity threshold ( NOEC) was 200 µ g ae/ L for freshwater vascular; acute toxicity thresholds ( EC50) were 3,250 and 61 µ g ae/ L for freshwater vascular and freshwater non vascular ( blue green algae), respectively. 58 2. Non target Terrestrial Animals For assessment of dicamba exposure to non target terrestrial birds, mammals and plants, four application scenarios were chosen to represent typical use scenarios ( Table II. c.). The four application scenarios evaluated were; sugarcane with maximum labeled use rate of 2.8 lbs ae/ acre; hay, pasture/ rangeland, soybean and agricultural fallowland with a maximum labeled use rate of 2.0 lbs ae/ acre; agricultural premises, oats and wheat with a maximum labeled use rate of 1.0 lbs ae/ acre and corn with a maximum labeled use rate of 0.75 lbs ae/ acre. Avian and terrestrial mammal EECs were modeled for each of the four scenarios using T REX 1.2.3 and non target terrestrial plant EECs were modeled for ground and aerial spray application using TerrPlant 1.0. Risk quotients were calculated using the modeled EECs and the acute and chronic toxicity endpoints in Tables IV. f and IV. g., respectively.

TABLE IV. f. Summary of endpoints for Dicamba acute terrestrial toxicity studiesa Organism Group Dicamba Acid MRID #

bird ( oral dose), LD50, mg ae/ kg bw 188 42774105 mammal, LD50, mg/ kg bw 2,740 00078444 terrestrial monocots emergence, EC25, lbs ae/ A 0.0044 42846301 terrestrial dicots emergence, EC25, lbs ae/ A 0.0027 42846301 terrestrial monocots vegetative vigor, EC25, lbs ae/ A 0.1507 42846301 terrestrial dicots vegetative vigor, EC25, lbs ae/ A 0.0068 42846301 a Details for each study are presented in earlier sections of this document and in Appendix .

TABLE IV. g. Summary of endpoints for Dicamba chronic terrestrial toxicity studiesa Organism Group Dicamba Acid MRID #

bird, NOEC Mallard ppm ae 695 43814003 mammal, NOAEC, mg ai/ kg bw/ day Rat 45 43137101 a Details for each study are presented in earlier sections of this document and in Appendix .

Birds Acute avian RQs were calculated using the oral gavage study with bobwhite quail and the 21 day oral LD 50 value of > 188 mg/ kg ( MRID 42774105). Assuming the dicamba application rates of 2.8 lbs ae/ acre and 2.0 lbs ae/ acre and maximum predicted residue levels, the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC were exceeded for small ( 20g and 100g) birds consuming short grass, tall grass and broadleaf forage and small insects and for large birds ( 1000g) consuming short grass ( Table IV. h). The Acute Restricted Use LOC and Listed Species LOC was exceeded for small ( 20 g) birds consuming fruits, pods, seeds and large insects and large 59 birds ( 1000g) consuming tall grass and broadleaf forage and small insects with the 100 g bird also exceeding the Listed Species LOC for fruit, pods, seeds and large insects.

For mean predicted residues, there were exceedances of the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC for the 20g and 100g bird consuming residues on short grass, the 20g bird consuming tall grass and broadleaf forage and small insects. The Acute Restricted Use LOC and Listed Species LOC were exceeded for the 100 g bird consuming the mean predicted residues on tall grass, broadleaf forage and small insects and the 1000g bird consuming short grass. The Listed Species LOC was exceeded for the 20 g bird consuming fruits, pods, seeds and large insects and the 1000g bird exposed to tall grass and small insects; however, there were no exceedances for the 100g and 1000g bird consuming the mean predicted residue on fruits, pods, seeds and large insects ( Table IV. h.).

TABLE IV. h. Avian Acute ( Dose based) Risk Quotient Summary a, b, c, d, e, f Food type Weight class ( g) 2.8 lbs ae/ acre 2.0 lbs ae/ acre Acute RQ Acute RQ predicted maximum residues predicted mean residues predicted maximum residues predicted mean residues short grass 20 5.65*** 2.00*** 4.04*** 1.43***

100 2.53*** 0.90*** 1.81*** 0.64***

1000 0.80*** 0.28** 0.57*** 0.20**

tall grass 20 2.59*** 0.85*** 1.85*** 0.61***

100 1.16*** 0.38** 0.83*** 0.27**

1000 0.37** 0.12* 0.26** 0.09 broadleaf forage, small insects 20 3.18*** 1.06*** 2.27*** 0.76***

100 1.42*** 0.47** 1.02*** 0.34**

1000 0.45** 0.15* 0.32** 0.11*

fruit, pods, seeds, large insects 20 0.35** 0.16* 0.25** 0.12*

100 0.16* 0.07 0.11* 0.05 1000 0.05 0.02 0.04 0.02 a Acute toxicity threshold was LD50 = 188 mg ae/ kg bw. b Detailed calculations for Acute RQs and input and output for T REX Ver. 1.2.3 are provided in Appendix C. c RQs in this table were calculated for the maximum labeled application rate of 2.8 lbs ae/ acre for sugarcane and 2.0 lbs ae/ acre for hay, pasture/ rangeland, soybean and agricultural fallowland. d * indicates an exceedance of Endangered Species Level of Concern ( LOC); RQ > 0.10. e** indicates an exceedance of Acute Restricted Use LOC; RQ > 0.20. f*** indicates an exceedance of Acute Risk LOC; RQ > 0.50.

For the dicamba application rates of 1.0 lbs ae/ acre and 0.75 lbs ae/ acre and maximum predicted residue levels, the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC were exceeded for small ( 20g and 100g) birds consuming short grass and broadleaf forage and small insects and the 20 g bird consuming tall grass ( Table IV. i.) The Acute Restricted Use LOC and Listed Species LOC was exceeded for the 100g bird consuming tall grass and the 1000g bird consuming short grass. The Listed Species LOC was exceeded for the 1000g bird consuming tall grass, broadleaf forage and small insects as well as the 20g bird consuming fruit, pods, seeds and 60 large insects based on maximum predicted residues. Based on mean predicted dicamba residues, the 20g bird exceeded the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC when consuming short grass. The Acute Restricted Use and Listed Species LOC were exceeded by the100 g bird consuming mean residues on short grass, and the 20 g bird consuming tall grass and broadleaf forage and small insects. Likewise, the 100g bird exceeded the Listed Species LOC when consuming tall grass, broadleaf forage and small insects based on the mean predicted residues ( Table IV. i).

TABLE IV. i. Avian Acute ( Dose based) Risk Quotient Summary a, b, c, d, e, f Food type Weight class ( g) 1.0 lbs ae/ acre 0.75 lbs ae/ acre Acute RQ Acute RQ predicted maximum residues predicted mean residues predicted maximum residues predicted mean residues short grass 20 2.02*** 0.72*** 1.51*** 0.54***

100 0.90*** 0.32** 0.68*** 0.24**

1000 0.29** 0.10 0.21** 0.08 tall grass 20 0.92*** 0.30** 0.69*** 0.23**

100 0.41** 0.14* 0.31** 0.10*

1000 0.13* 0.04 0.10* 0.03 broadleaf forage, small insects 20 1.14*** 0.38** 0.85*** 0.28**

100 0.51*** 0.17* 0.38** 0.13*

1000 0.16* 0.05 0.12* 0.04 fruit, pods, seeds, large insects 20 0.13* 0.06 0.09* 0.04 100 0.06 0.03 0.04 0.02 1000 0.02 0.01 0.01 0.01 a Acute toxicity threshold was LD50 = 188 mg ae/ kg bwt. b Detailed calculations for Acute RQs and input and output for T REX Ver. 1.2.3 are provided in Appendix C. c RQs in this table were calculated for the maximum labeled application rate of 1.0 lbs ae/ acre for wheat and 0.75 lbs ae/ acre for corn. d * indicates an exceedance of Listed Species Level of Concern ( LOC); RQ > 0.10. e** indicates an exceedance of Acute Restricted Use LOC; RQ > 0.20. f*** indicates an exceedance of Acute Risk LOC; RQ > 0.50.

TABLE IV. j. Avian Chronic ( Dietary based) Risk Quotient Summary a, b, c, d Food type 2.8 lbs ae/ acre Chronic RQ predicted maximum residues predicted mean residues short grass 0.97 0.34 tall grass 0.44 0.15 broadleaf forage, small insects 0.54 0.18 fruits, pods, large insects 0.06 0.03 a Chronic toxicity threshold was mallard NOAEC = 695 mg ae/ kg diet. b Detailed calculations for Chronic RQs and input and output for T REX Ver. 1.2.3 are provided in Appendix C. c RQs in this table were calculated for the maximum labeled application rate of 2.8 lbs ae/ acre for sugarcane. d* Indicates exceedance of chronic risk LOC; RQ > 1.0. 61 Table IV. j. presents the avian chronic RQs for the 2.8 lbs ae/ acre application rate for sugarcane. Avian chronic LOCs were not exceeded for all food items for all weight classes of birds consuming maximum or mean predicted dicamba residues on food items based on the mallard NOEAC of 695 ppm ae ( MRID 43814003). Likewise, there were no exceedances of avian chronic LOCs for the dicamba application rates of 2.0, 1.0 and 0.75 lbs ae/ acre ( results presented in Appendix C).

Mammals To evaluate the acute risk to mammals, RQs were calculated using the minimum LD 50 obtained from the acute oral studies ( 2,740 mg/ kg bw MRID 00078444) and the maximum labeled rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre as previously described. To evaluate the chronic ( developmental/ reproductive) risk to mammals, RQs were calculated using the rat NOAEC of 45 mg/ kg bw/ day ( MRID 43137101). The RQs are summarized in Tables IV. k. and IV. l. and details are presented in Appendix C.

Assuming maximum residue levels at the maximum single application rate for sugarcane ( 2.8 lbs ae/ acre), there were was one exceedance of the Acute Listed Species LOC for the 20 g mammal consuming short grass ( Table IV. k.) For all other food types and weight classes ( 15 g, 35 g, and 1000g) of mammals consuming maximum predicted residues on short grass, tall grass, broadleaf forage/ small insects and seeds the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs were not exceeded. Likewise, the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs were not exceeded for any weight class of mammal consuming the mean predicted residues ( Table IV. k.).

Evaluation of the 2.0, 1.0 and 0.75 lbs ae/ acre maximum application rates for acute risk to mammals indicates no exceedances of the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs for any weight class of mammal consuming the maximum or mean predicted residues ( results for 1.0 and 0.75 lbs ae/ acre application rates presented in Appendix C). 62 TABLE IV. k. Mammalian Acute ( Dose based) Risk Quotient Summary a, b, c, d Food type Weight class ( g) 2.8 lbs ae/ acre 2.0 lbs ae/ acre Predicted maximum residues Predicted mean residues Predicted maximum residues Predicted mean residues short grass 15 0.11* 0.04 0.08 0.03 35 0.09 0.03 0.07 0.02 1000 0.05 0.02 0.03 0.01 tall grass 15 0.05 0.02 0.03 0.01 35 0.04 0.01 0.03 0.01 1000 0.02 0.01 0.02 0.01 broadleaf forage, small insects 15 0.06 0.02 0.04 0.01 35 0.05 0.02 0.04 0.01 1000 0.03 0.01 0.02 0.01 fruit, large insects 15 0.01 < 0.01 < 0.01 < 0.01 35 0.01 < 0.01 < 0.01 < 0.01 1000 < 0.01 < 0.01 < 0.01 < 0.01 seeds, pods 15 < 0.01 < 0.01 < 0.01 < 0.01 35 < 0.01 < 0.01 < 0.01 < 0.01 1000 < 0.01 < 0.01 < 0.01 < 0.01 a Acute toxicity threshold was LD50 = 2,740 mg/ kg bwt. b Detailed calculations for Acute RQs are provided in Appendix C as well as input and output from T REX Ver. 1.2.3. c RQs in this table were calculated for the maximum labeled application rate of 2.8 lbs ae/ acre for sugarcane and 2.0 lbs ae/ acre for hay, pasture/ rangeland, soybean and agricultural fallowland. d* Indicates exceedance of Acute Listed Species LOC; RQ > 0.1.

For chronic risk to mammals, the Chronic Risk LOC was exceeded for mammals consuming maximum and mean predicted residues on short grass at the 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre maximum application rates ( Table IV. l.). For tall grass, broadleaf forage and small insects, the Chronic risk LOC was exceeded for mammals consuming maximum residues at application rates of 2.8, 2.0, and 1.0 lbs ae/ acre. There were no exceedances of the Chronic Risk LOC for mammals consuming the maximum residues on fruit, pods and large insects. The Chronic Risk LOC was exceeded for mean residues for broadleaf forage and small insects at the 2.8 lbs ae/ acre application rate. 63 Table IV. l. Mammalian Chronic ( Dose based) Risk Quotients a, b, c Food type Weight class ( g) 2.8 lbs ae/ acre 2.0 lbs ae/ acre 1.0 lbs ae/ acre 0.75 lbs ae/ acre predicted residues max. mean max. mean max. mean max. mean short grass 15 6.48* 2.29* 4.63* 1.63* 2.31* 0.82 1.74* 0.61 35 5.53* 1.96* 3.95* 1.40* 1.98* 0.70 1.48* 0.53 1000 2.97* 1.03* 2.12* 0.74 1.06* 0.37 0.79 0.28 tall grass 15 2.97* 0.97 2.12* 0.69 1.06* 0.35 0.80 0.26 35 2.54* 0.83 1.81* 0.59 0.91 0.30 0.68 0.22 1000 1.36* 0.44 0.97 0.31 0.49 0.16 0.36 0.12 broadleaf forage, small insects 15 3.64* 1.21* 2.60* 0.86 1.30* 0.43 0.98 0.32 35 3.11* 1.04* 2.22* 0.74 1.11* 0.37 0.83 0.28 1000 1.67* 0.55 1.19* 0.39 0.60 0.20 0.45 0.15 fruit, pods, large insects 15 0.40 0.19 0.29 0.13 0.14 0.07 0.11 0.05 35 0.35 0.16 0.25 0.12 0.12 0.06 0.09 0.04 1000 0.19 0.08 0.13 0.06 0.07 0.003 0.05 0.02 a Chronic toxicity threshold was NOAEC = 45 mg ae/ kg bw/ day. b Detailed calculations for Chronic RQs and input and output from T REX Ver. 1.2.3 are provided in Appendix C. c* Indicates exceedance of Chronic Risk LOC; RQ> 1.0.

Terrestrial Non Target Insects EFED currently does not quantify risks to terrestrial non target insects; therefore, risk quotients are not calculated for these organisms. Risks are qualitatively discussed in the Terrestrial Organism Risk Description section of this document.

3. Non target Terrestrial and Plants in Semi aquatic Habitats Table IV. m. presents RQs for terrestrial plants for four dicamba application rates for both ground and aerial spray applications. The acute risk LOC was exceeded for non listed monocots and dicots located adjacent to treated areas and in semi aquatic areas based on dicamba maximum application rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre as the result of ground and aerial spray application ( Table IV. m.). Spray drift from ground and aerial spray application resulted in exceedance of the Acute Risk LOC for non listed dicots when applied at 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre. Spray drift did not result in exceedance of the acute LOC for non listed monocots. The terrestrial plant Acute Listed Species LOC was exceeded for monocots and dicots located adjacent to treated areas and in semi aquatic areas based on dicamba maximum application rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre as the result of ground and aerial spray application ( Table IV. m.). Spray drift from ground and aerial spray application resulted in exceedance of the Acute Listed LOC for dicots based on dicamba application rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre. The only spray drift exceedance of the Acute Listed LOC for monocots was as the result of exposure when applied aerially at a rate of 2.8 lbs ae/ acre. 64 Currently, EFED does not perform chronic risk assessments for terrestrial plants. 65 TABLE IV. m. Summarized Terrestrial Plant Acute Risk Quotients a, b, c, d, e Scenario Acute Non listed RQs Acute Listed RQs Adjacent to treated sites Semi aquatic areas Drift Adjacent to treated sites Semi aquatic areas Drift Sugarcane ( 2.8 lbs ae/ A)

Ground spray application Monocot 3.96** 33.68** 0.19 5.25* 44.63* 0.22 Dicot 62.22** 528.89** 4.12** 76.36* 649.09* 7.00*

Aerial spray application Monocot 5.28** 23.11** 0.93 7.00* 30.63* 1.08*

Dicot 82.96** 362.96** 20.59** 101.82* 445.45* 35.00*

Hay, pasture/ rangeland, soybean and agricultural fallowland ( 2.0 lbs ae/ A)

Ground spray application Monocot 2.83** 24.06** 0.13 3.75* 31.88* 0.15 Dicot 44.44** 377.78** 2.94** 54.55* 463.64* 5.00*

Aerial spray application Monocot 3.77** 16.51** 0.66 5.00* 21.88* 0.77 Dicot 59.26** 259.26** 14.71** 72.73* 318.18* 25.00*

Wheat ( 1.0 lbs ae/ A)

Ground spray application Monocot 1.42** 12.03** 0.07 1.88* 15.94* 0.08 Dicot 22.22** 188.89** 1.47** 27.27* 231.82* 2.50*

Aerial spray application Monocot 1.89** 8.25** 0.33 2.50* 10.94* 0.38 Dicot 29.63** 129.63** 7.35** 36.36* 159.09* 12.50*

Corn ( 0.75lbs as/ A)

Ground spray application Monocot 1.06** 9.02** 0.05 1.41* 11.95* 0.06 Dicot 16.67** 141.67** 1.10** 20.45* 173.86* 1.88*

Aerial spray application Monocot 1.42** 6.19** 0.25 1.88* 8.20* 0.29 Dicot 22.22** 97.22** 5.51** 27.27* 119.32* 9.38*

a Detailed calculations for Acute RQs and TerrPlant Ver. 1.0 input and output are provided in Appendix D. b Acute non listed toxicity thresholds ( EC25) were 0.0424, 0.0027, 0.1507, and 0.0068 lb ae/ acre for seedling emergence monocot, seedling emergence dicot, vegetative vigor monocot, and vegetative vigor dicot, respectively. c Acute listed toxicity thresholds ( NOAEC/ EC05) were 0.032, 0.0022, 0.13, and 0.004 lb ae/ acre for seedling emergence monocot, seedling emergence dicot, vegetative vigor monocot, and vegetative vigor dicot, respectively. d * indicates an exceedance of the Listed Species Level of Concern; RQ> 1.0. e** indicates an exceedance of the Acute Risk LOC: RQ> 1.0.

B. Risk Description 66 1. Risks to Aquatic Organisms: In the conceptual model, spray drift and surface runoff/ leaching to adjacent bodies of water were predicted as the most likely sources of exposure of dicamba and the salts of dicamba to nontarget aquatic organisms. An additional predicted source of potential exposure to benthic organisms was through accumulated residues in sediments. Risks to aquatic organisms ( i. e. fish, invertebrates, and plants) were assessed based on modeled Estimated Environmental Concentrations ( EECs) and available toxicity data. Aquatic EECs ( Table III. b) for the ecological exposure to dicamba were estimated using PRZM/ EXAMS employing the standard field pond scenario for each crop location identified in Table II. d..

Fish and Invertebrates Available acute toxicity data for aquatic species indicate that dicamba is practically non toxic to fish and invertebrates with LC 50 and EC 50 values for fish and invertebrates of 28 mg/ L and 34.6 mg/ L, respectively. Acute risk quotients of < 0.01 ( Tables IV. d and e., respectively) were calculated for the various crop scenarios ( Table II. d.) when dicamba is applied and it is assumed that the herbicide reaches the surface water via runoff and spray drift as estimated by PRZM/ EXAMS ( Table III. c.). There were no exceedances of the aquatic Acute Risk, Acute Restricted Use, Listed Species, and Chronic Risk LOCs for fish and invertebrates. Consequently, freshwater fish and invertebrates inhabiting surface waters adjacent to a dicamba treated field would not be at risk for adverse acute effects on survival when exposed to dicamba residues in surface runoff and spray drift as a result of ground and/ or aerial spray application. However, there are no chronic studies for fish and invertebrates thus chronic effects to survival, growth and reproduction of fish and invertebrates remains an uncertainty. Likewise, due to insufficient toxicity data, risk to sediment dwelling benthic organisms remains an uncertainty.

Aquatic Plants Toxicity studies indicate that dicamba is not toxic to aquatic vascular plants with the EC 50 for the freshwater vascular plant ( duckweed) of 3.25 mg/ L ( NOEC 0.20 mg/ L) based on inhibition of plant growth and reduction of frond count. Toxicity studies with blue green algae indicate a reduction in cell density at dicamba test concentrations as low as 0.008 mg/ L. The EC 50 for the freshwater non vascular plant ( blue green algae) was 0.061mg/ L.

For the dicamba use scenarios modeled ( Table II. d.), there were no exceedances of the nonlisted Acute Risk LOC for freshwater vascular plants ( Table IV. e.). However, the LOCs for non listed freshwater non vascular plants ( blue green algae) were exceeded for the 2.8 lbs ae/ acre and 2.0 lbs ae/ acre application rates to crops by ground and aerial spray assuming that the maximum predicted dicamba concentrations would come in contact with freshwater nonvascular plants. Consequently, non listed aquatic non vascular plants inhabiting surface waters adjacent to a treated field would be at risk for adverse effects to growth and development when exposed to dicamba as a result of the labeled uses of the pesticide. The potential risk to listed aquatic vascular plants will be discussed in greater detail in Section IV. B. 4.

2. Risks to Terrestrial Organisms: In the conceptual model, ground deposition, spray drift, root uptake, and wind erosion of soil particles with resulting residues on foliage and on insects 67 and seeds are the most likely sources of dicamba exposure to nontarget terrestrial organisms, including listed species. An additional predicted source of exposure to dicamba was in puddled water on treated fields through preening and grooming, involving the oral ingestion of material from the feathers or fur.

Risks to terrestrial organisms ( i. e. birds, mammals, and plants) were assessed based on modeled EECs and available toxicity data. As part of the terrestrial assessment, EFED modeled exposure concentrations of dicamba to nontarget terrestrial plants and animals following the proposed application rates for various crops provided by the registrant ( Table II. d.). For terrestrial birds and mammals, estimates of initial levels of dicamba residues on various food items, which may be contacted or consumed by wildlife, were determined using the Fletcher nomogram followed by a first order decline model ( T REX 1.2.3). Likewise, the TerrPlant 1.0 model estimated exposure to nontarget plants.

Birds Dicamba salts are categorized as practically non toxic to avian species based on dietary studies. However, oral gavage studies indicate dicamba acid was moderately toxic to bobwhite quail ( 21 day LD 50 188 mg/ kg) and slightly toxic to mallard ducks ( NOEL could not be determined due to signs of toxicity at all test levels). Chronic avian studies with dicamba acid showed a reduction in hatchability in mallard ducks at 1390 ppm a. e. ( NOAEC = 695 a. e.).

Based on the oral study and assuming maximum application rates of 2.8 and 2.0 lbs ae/ acre and maximum predicted residue levels for ground spray applications, the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC were exceeded for small ( 20g and 100g) birds consuming short grass, tall grass and broadleaf forage and small insects and for large birds ( 1000g) consuming short grass ( Table IV. h). The Acute Restricted Use LOC and Listed Species LOC was exceeded for small ( 20 g) birds consuming fruits, pods, seeds and large insects and large birds ( 1000g) consuming tall grass and broadleaf forage and small insects with the 100 g brid also exceeding the Listed Species LOC for these food items.

There were exceedances of the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC for the 20g and 100g bird consuming the mean predicted residues on short grass, the 20g bird consuming tall grass and broadleaf forage and small insects. The Acute Restricted Use LOC and Listed Species LOC were exceeded for the 100 g bird consuming the mean predicted residues on tall grass, broadleaf forage and small insects and the 1000g bird consuming short grass. The 20 g bird consuming the mean predicted residue on fruits, pods, seeds and large insects exceeded the Listed Species LOC; however, there were no exceedances for the 100g and 1000g bird consuming the mean predicted residue on fruits, pods, seeds and large insects ( Table IV. h.).

For the dicamba application rates of 1.0 lbs ae/ acre and 0.75 lbs ae/ acre and maximum predicted residue levels, the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC were exceeded for small ( 20g and 100g) birds consuming short grass and broadleaf forage and small insects and the 20 g bird consuming tall grass ( Table IV. i.) The Acute Restricted Use LOC and Listed Species LOC was exceeded for the 100g bird consuming tall grass and the 1000g bird consuming short grass. The Listed Species LOC was 68 exceeded for the 1000g bird consuming tall grass, broadleaf forage and small insects as well as the 20g bird consuming fruit, pods, seeds and large insects based on maximum predicted residues.

Based on mean predicted dicamba residues, the 20g bird exceeded the Acute Risk LOC, Acute Restricted Use LOC and the Listed Species LOC when consuming short grass. The Acute Restricted Use and Listed Species LOC were exceeded by the100 g bird consuming mean residues on short grass, and the 20 g bird consuming tall grass and broadleaf forage and small insects. Likewise, the 100g bird exceeded the Acute Restricted Use LOC and the Listed Species LOC when consuming short grass and the Listed Species LOC when consuming tall grass, broadleaf forage and small insects based on the mean predicted residues ( Table IV. i). The potential risk to listed birds ( 20g, 100g and 1000g) will be discussed in greater detail in Section IV. B. 4.

Based on an NOAEC of 695 mg ai/ kg for mallard duck and assuming maximum application rates ( 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre), the Chronic Risk LOC was not exceeded ( Table IV. j.); consequently, birds would not be at risk from chronic developmental/ reproductive effects when exposed to dicamba as a result of the labeled uses of the pesticide.

Mammals Dicamba acid is classified as practically non toxic to small mammals on an acute oral basis ( LD 50 value of > 2,740 mg/ kg bw). A 13 week subchronic oral study in rats reported body weight changes and liver effects at 1000 mg a. i./ kg/ day. Developmental studies with rabbits reported irregular ossification of internasal bones at 300 mg a. i./ kg/ day ( dicamba acid, 90.5% a. i.) and maternal toxicity ( abortion and clinical signs of toxicity, including ataxia, rales, and decreased motor activity) was reported at 150 mg a. i./ kg/ day. Maternal toxicity; including mortality, clinical signs of toxicity, body weight changes, and decreased food consumption, was also observed in rats at 400 mg a. i./ kg/ day ( dicamba acid, 85.8% a. i.). In a 2 generation reproduction study with rats ( dicamba acid, 86.5% a. i.), maternal neurotoxicity was observed at doses of 419 mg a. i./ kg/ day in males and at 450 mg a. i./ kg/ day in females and developmental effects, decreased pup growth, were observed in rats at a dose of 136 mg a. i./ kg/ day; consequently, the NOAEC was 45 mg a. i./ kg diet To evaluate the acute risk to mammals, RQs were calculated using the minimum LD 50 obtained from the acute oral studies ( 2,740 mg/ kg bw MRID 00078444) and the maximum labeled rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre as previously described. To evaluate the chronic ( developmental/ reproductive) risk to mammals, RQs were calculated using the rat NOAEC of 45 mg/ kg diet ( MRID 43137101).

Assuming maximum residue levels at the maximum application rate for sugarcane ( 2.8 lbs ae/ acre), there were was one exceedance of the Acute Listed Species LOC for the 20 g mammal consuming short grass ( Table IV. k.) For all other food types and weight classes ( 15 g, 35 g, and 1000g) of mammals consuming maximum predicted residues on short grass, tall grass, broadleaf forage/ small insects and seeds the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs were not exceeded. Likewise, the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs were not exceeded for any weight class of mammal consuming the mean predicted residues ( Table IV. k.). Furthermore, evaluation of the 2.0, 1.0 69 and 0.75 lbs ae/ acre application rates for acute risk to mammals indicates no exceedances of the Acute Listed Species, Acute Restricted Use and Acute Risk LOCs for any weight class of mammal consuming the maximum or mean predicted dicamba residues on food items.

Based on the rat NOEAC of 45 mg/ kg diet, the Chronic Risk LOC was exceeded for mammals consuming maximum and mean predicted dicamba residues on short grass at the 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre maximum application rates ( Table IV. l.). For tall grass, broadleaf forage and small insects, the Chronic Risk LOC was exceeded for mammals consuming maximum residues at application rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre. There were no exceedances of the Chronic Risk LOC for mammals consuming the maximum residues on fruit, seeds, pods and large insects ( Table IV. l). As a result, mammals could be at risk for developmental/ reproductive effects or direct effects on foraging behavior when chronically exposed to dicamba as a result of the labeled uses of the herbicide.

Terrestrial Non target Insects EFED currently does not quantify risks to terrestrial non target insects. Risk quotients are therefore not calculated for these organisms. Since, dicamba is classified as practically nontoxic to bees on a contact exposure basis ( LD 50 > 90.65 µ g/ bee); the potential for dicamba to have adverse effects on pollinators and other beneficial insects is low. Therefore, the label does not need a warning for honey bees.

Terrestrial and Semi aquatic Plants Results of Tier II toxicity studies with monocots and dicots indicate that seedling emergence and vegetative vigor are impacted by exposure to dicamba acid. Seedling emergence, based on weight, was adversely impacted in monocots ( onion) at an EC 25 of 0.0044 lb ae/ A and in dicots ( soybean) with an EC 25 of 0.0027 lb ae/ A. Vegetative vigor in monocots, based on weight, was adversely impacted by dicamba acid at an EC 25 of 0.1507 lb ae/ A in onion and 0.0068 lb ae/ A in soybean, respectively. The observed effects to monocots and dicots included stunting, chlorosis, and plant death.

Based on the toxicity data presented above, the results indicate that for the crop scenarios evaluated and the application rates of 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre the Acute Risk LOC ( with the exception of monocots as the result of drift) and the Listed Species LOC were exceeded for monocots and dicots located adjacent to treated areas, in semi aquatic areas and as a result of spray drift ( Table IV. m). For the application rates evaluated ( 2.8, 2.0, 1.0 and 0.75 lbs ae/ acre), both ground and aerial spray application resulted in exccedance of the Acute Risk LOC and Listed Species LOC. The potential risk to listed non target terrestrial and semi aquatic plant species will be discussed in greater detail in Section IV. B. 4.

Spray drift is also an important factor in characterizing the risk of dicamba to non target plants. In comparison, the terrestrial plant RQs when aerial application is used are greater than RQs from ground spray application. Spray drift exposure from ground spray application is assumed to be 1% of the application rate and the EECs and RQs were calculated using EFED's TerrPlant. xls model ( Version 1.0). Therefore, EFED's TerrPlant model can be interpreted to represent exposure to non target terrestrial plants in either of two ways. First, TerrPlant estimates the exposure to drift from ground spray at a distance of 25 ft from the edge of the field. Distances closer to the field than 25 ft would have an exposure higher than 70 modeled by TerrPlant and distances farther than 25 ft from the field would have an exposure lower than the modeled values. A second interpretation is that TerrPlant models the average exposure across a swath 175 feet wide starting at the edge of the field. Within this swath, the exposure is higher close to the edge of the field than it is at distances further from the field. Likewise, spray drift exposure from aerial application is assumed to be 5% of the application rate using EFED's TerrPlant. xls model ( Version 1.0) for calculating EECs and RQs.

The results of this screening risk assessment indicate that dicamba use on cropped areas applied at the labeled concentration rates as a liquid spray for ground or aerial applications presents a risk to non target plants for some distance from the application site. Exposure will depend on droplet size, wind speed, and other factors. Spray drift from coarse sprays would be expected to damage non target plants that are closer to the target site; whereas, finer sprays have the potential to travel greater distances. Dicamba acid and its' salts in formulated TEPs is readily absorbed through the foliage and roots of plants; consequently, it could be injurious to non target plant species by drift, runoff, or leaching to roots. Damage to nontarget plants may be sufficient to prevent the plant from competing successfully with other plants for resources and water. Dicamba may accumulate in the soil with frequent or extensive use which may result in damage to trees, shrubs, or other ornamentals. Residuals of dicamba in soil have been shown to reduce emergence in sugarbeet and cause petiole epinasty, severe stunting of seedlings, and trumpeting ( Dexter et al, 1994). Listed plant species may be especially impacted by exposure to dicamba because of the impact of the loss of a few individuals to the population. Low level exposure to non target crops can cause severe reductions in yield. Numerous cases of soybean injury are reported yearly from the use of dicamba on corn that results in the exposure of adjacent fields of soybean to dicamba through spray drift and volatilization ( Proost and Boerboom 2004; Hartzler 2003). Injury includes leaf malformations, terminal bud kill, and delayed maturity. Yield loss can occur if soybeans are exposed to dicamba after they bloom ( in the reproductive stage).

The results of this screening risk assessment indicate that direct effects to plant species could present an indirect risk at the higher levels of organization ( i. e. population, trophic level, community, ecosystem). Field studies are not available to quantify actual risk to plant and animal communities in forest/ edge and wetland/ riparian habitats. However, in terrestrial and shallow water aquatic communities, plants are the primary producers upon which the succeeding trophic levels depend. If the available plant material is impacted due to the effects of dicamba and the salts of dicamba, this may have negative effects not only on the herbivores, but throughout the food chain. Also, depending on the severity of impacts to the plant communities [ i. e., forests, wetlands, ecotones ( edge and riparian habitats)], community assemblages and ecosystem stability may be altered ( i. e. reduced bird populations in edge habitats; reduced riparian vegetation resulting in increased light penetration and temperature in aquatic habitats, loss of cover and food for fish). In addition, allochthonous input from riparian vegetation is not only a significant component of the food supply for aquatic herbivores and detritivores but also provides habitat ( i. e. leaf packs, materials for casebuilding for invertebrates).

3. Review of Incident Data: FIFRA 6( a)( 2) incident data add lines of evidence to provide evidence that the risk predictions from the screening level assessment are substantiated with 71 actual effects in the field. Incident data for dicamba and dicamba salts is summarized below. There was no incident data reported for the isopropylamine salt of dicamba.

Dicamba: Thirty five incidents resulting from dicamba use have been recorded in the Ecological Incident Information System ( EIIS) as of June 1, 2005. Incidents reported include terrestrial, plants, and aquatic impacts. There was a single terrestrial impact in Utah involving the mortality of several horses and dogs as well as numerous squirrels and chipmunks as a result of the spray application of dicamba. Impacts to plants included a wide range of crops ( soybeans, corn, wheat) as well as non agricultural application. The specific impacts varied from browning and plant damage to mortality of all plants within the treated area. Aquatic impacts consist of 2 fish kill incidents associated with agricultural and residential turf application.

Dicamba Sodium Salt: Fifteen incidents resulting from dicamba, sodium salt use have been recorded in the EIIS as of June 1, 2005. All reported incidents reported where associated with plant damage to crops including sorghum, soybean, corn, and sugar beets.

Dicamba Dimethylamine Salt: Forty six incidents resulting from dicamba, dimethylamine salt use have been recorded in the EIIS as of June 1, 2005. Incidents reported include plant and aquatic impacts. The majority ( 40/ 45) of impacts to plants where associated with residential turf application and ranged from browning to mortality. Agricultural application resulted in plant damage to cotton, corn and soybeans. The single reported aquatic incident was a fish kill of unknown magnitude resulting from turf application.

Dicamba Potassium Salt: Three incidents resulting from dicamba, potassium salt use have been recorded in the EIIS as of June 1, 2005. There were 2 incidents reported of impacts to plants, both associated with application on corn resulting in plant damage. The sole aquatic impact was associated with agricultural application which resulted in the mortality of 2000 Perch.

Dicamba Diglycoamine Salt: Two incidents resulting from dicamba, diglycoamine salt use have been recorded in the EIIS as of June 1, 2005. Both incidents were associated with impacts to plants ( soybeans) which resulted in plant damage.

4. Federally Listed Species Concerns Action Area For listed species assessment purposes, the action area is considered to be the area affected directly or indirectly by the Federal action and not merely the immediate area involved in the action. At the initial screening level, this risk assessment considers broadly described taxonomic groups and so conservatively assumes that listed species within those broad groups are collocated with the pesticide treatment area. This means that terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site and aquatic organisms are assumed to be located in a surface water body adjacent to the treated site. This assessment also assumes that the listed species are located within an assumed area which has the relatively highest potential exposure to the pesticide, and that exposures are likely to decrease with 72 distance from the treatment area. Section II. A. 4. of this risk assessment presents the pesticide use sites that are used to establish initial collocation of species with treatment areas. If the assumptions associated with the screening level action area result in RQs that are below the listed species LOCs, a " no effect" determination conclusion is made with respect to listed species in that taxa, and no further refinement of the action area is necessary. Consequently, for this risk assessment for dicamba, a " no effect" determination can be made for listed species of fish, aquatic invertebrates, and vascular aquatic plants; since the acute risk RQs for these taxonomic groups did not exceed the Listed Species LOCs. Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no concern for indirect effects upon listed species that depend upon the taxonomic group covered by the RQ as a resource. However, in situations where the screening assumptions lead to RQs in excess of the listed species LOCs for a given taxonomic group, a potential for a " may affect" conclusion exists and may be associated with direct effects on listed species belonging to that taxonomic group or may extend to indirect effects upon listed species that depend upon that taxonomic group as a resource. In such cases, additional information on the biology of listed species, the locations of these species, and the locations of use sites and could be considered along with available information on the fate and transport properties of the pesticide to determine the extent to which screening assumptions regarding an action area apply to a particular listed organism. These subsequent refinement steps could consider how this information would impact the action area for a particular listed organism and may potentially include areas of exposure that are downwind and downstream of the pesticide use site. 73 Taxonomic Groups Potentially at Risk The preliminary risk assessment for listed species indicates that dicamba exceeds the Listed Species LOCs for the specified use scenario for the following taxonomic groups:

° small birds ( 20 and 100 g) feeding on short grasses, tall grasses, and broadleaf forage/ small insects at all application rates and maximum and mean predicted residue levels ° small birds ( 20 g) feeding on fruit, pods, seeds/ large insects at all application rates and maximum predicted residue levels ° small birds ( 20 g) feeding on fruit, pods, seeds/ large insects at 2.8 and 2.0 lbs ae/ acre and mean predicted residue levels ° small birds ( 100 g) feeding on fruit, pods, seeds/ large insects at 2.8 and 2.0 lbs ae/ acre and maximum predicted residue levels ° large birds ( 1000 g) feeding on short grasses, tall grasses, and broadleaf forage/ small insects at all application rates and maximum predicted residue levels ° large birds ( 1000 g) feeding on short grasses, tall grasses, and broadleaf forage/ small insects at 2.8 lbs ae/ acre and mean predicted residue levels ° large birds ( 1000 g) feeding on short grasses and broadleaf forage/ small insects at 2.0 lbs ae/ acre and mean predicted residue levels ° small ( 15 g) mammals feeding on short grasses at 2.8 lbs ae/ acre and maximum predicted residue levels ° non target terrestrial plants  monocots and dicots adjacent to treated areas and in semiaquatic areas at all application rates ( all uses modeled) by ground and aerial spray application; dicots in spray drift at all application rates ( all uses modeled) by ground and aerial spray application; monocots in spray drift at 2.8 lbs ae/ acre by aerial spray application.

Discussion of Risk Quotients: The Agency's LOC for listed birds, mammals, and non target terrestrial plants is exceeded for the use of dicamba as outlined in previous sections. Should estimated exposure levels occur in proximity to listed resources, the available screening level information suggests a potential concern for direct effects on listed species within these taxonomic groups listed above associated with the use of dicamba as described in Section II. A. 4. The registrant must provide information on the proximity of Federally listed small and large birds, small mammals, and non target terrestrial plants to the dicamba use sites. This requirement may be satisfied in one of three ways: 1) having membership in the FIFRA Listed Species Task Force ( Pesticide Registration [ PR] Notice 2000 2); 2) citing FIFRA Listed Species Task Force data; or 3) independently producing these data, provided the information is of sufficient quality to meet FIFRA requirements. The information will be used by the OPP Listed Species Protection Program to develop recommendations to avoid adverse effects to listed species.

Probit Dose Response Relationship: A probit dose response analysis was performed based on toxicity studies for daphnids, northern bobwhite, rats, and rainbow trout. It is recognized that extrapolation of very low probability events is associated with considerable uncertainty in the resulting estimates. Based on an assumption of a probit dose relationship with the mean estimated slope of 5.546, the corresponding estimated chance of individual mortality associated with the listed species LOC of 0.05, the acute toxic endpoint for daphnia are 1 in 74 3.72E+ 12. Based on an assumption of a probit dose relationship with the mean estimated slope of 6, the corresponding estimated chance of individual mortality associated with the listed species LOC of 0.1, the acute toxic endpoint for northern bobwhite is 1 in 1.01E+ 9. Based on an assumption of a probit dose relationship with the default estimated slope of 4.5, the corresponding estimated chance of individual mortality associated with the listed species LOC of 0.05, the acute toxic endpoint for rainbow trout is 1 in 4.17E+ 8. Based on an assumption of a probit dose relationship with the default estimated slope of 4.5 the corresponding estimated chance of individual mortality associated with the listed species LOC of 0.1, the acute toxic endpoint for rat is 1 in 2.94 E+ 05.

Data Related to Under represented Taxa: Additional effects data from other analyzed sources ( ECOTOX Database, PAN Database) include and/ or support guideline study data for dicamba and its salts and therefore, do not suggest that a given suite of listed taxa may be more or less sensitive than suggested by the effects data used for RQ calculations.

Implications of Sublethal Effects: Chronic studies were available for both upland game birds and waterfowl and for mammals. RQs did exceed Chronic LOCs for mammals consuming short grasses, tall grasses and broadleaf forage/ small insects at all application rates modeled and maximum predicted residue levels and at 2.8, 2.0, and 1.0 lbs ae/ acre and mean predicted residue levels; and for consumption of short grasses at 1.0 and 0.75 lbs ae/ acre and mean predicted residue levels. In a 2 generation reproduction study with Sprague Dawley rats ( dicamba acid, 86.5% a. i.; MRID 43137101), maternal neurotoxicity was observed at doses of 419 mg a. i./ kg/ day in males and at 450 mg a. i./ kg/ day in females and developmental effects ( decreased pup growth) were observed in rats at a dose of 136 mg a. i./ kg/ day. Developmental studies with New Zealand white rabbits reported irregular ossification of internasal bones at 300 mg a. i./ kg/ day ( dicamba acid, 90.5% a. i.; MRID 42429401) and maternal toxicity ( abortion and clinical signs of toxicity, including ataxia, rales, and decreased motor activity) was reported at 150 mg a. i./ kg/ day. Maternal toxicity; including mortality, clinical signs of toxicity, body weight changes, and decreased food consumption, was also observed in Charles River CD rats at 400 mg a. i./ kg/ day ( dicamba acid, 85.8% a. i.; MRID 00084024). In addition, sublethal effects in subchronic feeding studies ( 13 weeks) with Charles River CD rats included body weight changes and liver effects at 1000 mg a. i./ kg/ day. The reproductive and developmental effects observed in these studies may lead to a potential concern for impacts to populations of mammals consuming feed items contaminated with dicamba and to the predators that feed on them.

Indirect Effects Analysis The Acute Use and Acute Restricted Use LOCs were exceeded for all weight classes of birds ( 20, 100, 1000 g) consuming short grasses, tall grasses and broadleaf forage/ small insects and for small birds ( 20 g) consuming fruit, pods, seeds, and large insects at the higher application rates ( 2.8 and 2.0 lbs ae/ acre) and maximum predicted residues. In addition, the Acute Use and Acute Restricted Use LOCs were exceeded for 20 and 100 g birds consuming short grasses, tall grasses and broadleaf forage/ small insects and for large birds ( 1000 g) consuming short grasses at the lower application rates ( 1.0 and 0.75 lbs ae/ acre) and maximum predicted residues. For mean predicted residues, the Acute Use and Acute Restricted Use LOCs were exceeded for small birds ( 20 and 100 g) consuming short grasses, tall grasses and broadleaf forage/ small insects and for large birds ( 1000 g) consuming short grasses at the higher 75 application rates ( 2.8 and 2.0 lbs ae/ acre). In addition for mean predicted residues, the Acute Use and/ or Acute Restricted Use LOCs were exceeded for 20 g birds consuming short grasses, tall grasses and broadleaf forage/ small insects and for100 g birds consuming short grasses at the lower application rates ( 1.0 and 0.75 lbs ae/ acre). Consequently, there may be a concern for potential indirect effects to listed species dependent upon birds for food, pollination or seed dispersal, or habitat.

The Acute Non listed and Listed Species LOCs were exceeded for non target monocots and dicots adjacent to treated areas and in semi aquatic areas at all application rates ( 2.8, 2.0. 1.0 and .075 lbs ae/ acre) by ground and aerial spray application; for dicots in spray drift at all application rates by ground and aerial spray application; and monocots in spray drift at 2.8 lbs ae/ acre by aerial spray application. The guideline terrestrial plant studies indicate that dicamba negatively impacts seed germination ( radicle length), seedling emergence ( shoot length), and vegetative vigor ( shoot weight) in monocots and dicots. Non lethal effects included brown leaf tips, necrosis, decrease in size, leaf curling, chlorosis, and stem tumors. Dicamba acid and its'salts in formulated TEPs are readily absorbed through the foliage and roots of plants; consequently, it could be injurious to non target plant species by drift, runoff, or leaching to roots. Damage to non target plants may be sufficient to prevent the plant from competing successfully with other plants for resources and water. Listed plant species may be especially impacted by exposure to dicamba because of the impact of the loss of a few individuals to the population. Consequently, there is a potential concern for listed species with either broad or narrow dependencies on impacted plant species/ populations/ communities for habitat, feeding or cover requirements. In terrestrial and shallow water aquatic communities, plants are the primary producers upon which the succeeding trophic levels depend. If the available plant material is impacted due to the effects of dicamba and the salts of dicamba, this may have negative effects not only on the herbivores, but throughout the food chain. Also, depending on the severity of impacts to the plant communities [ i. e., forests, wetlands, ecotones ( edge and riparian habitats)], community assemblages and ecosystem stability may be altered ( i. e. reduced bird populations in edge habitats; reduced riparian vegetation resulting in increased light penetration and temperature in aquatic habitats, loss of cover and food for fish).

Critical Habitat In the evaluation of pesticide effects on designated critical habitat, consideration is given to the physical and biological features ( constituent elements) of a critical habitat identified by the U. S Fish and Wildlife and National Marine Fisheries Services as essential to the conservation of a listed species and which may require special management considerations or protection. The evaluation of impacts for a screening level pesticide risk assessment focuses on the biological features that are constituent elements and is accomplished using the screening level taxonomic analysis ( risk quotients, RQs) and listed species levels of concern ( LOCs) that are used to evaluate direct and indirect effects to listed organisms.

The screening level risk assessment has identified potential concerns for indirect effects on listed species for those organisms dependant upon birds, small mammals, and terrestrial and semi aquatic plants. In light of the potential for indirect effects, the next step for EPA and the Service( s) is to identify which listed species and critical habitat are potentially implicated. Analytically, the identification of such species and critical habitat can occur in either of two ways. First, the agencies could determine whether the action area overlaps critical habitat or 76 the occupied range of any listed species. If so, EPA would examine whether the pesticide's potential impacts on non listed species would affect the listed species indirectly or directly affect a constituent element of the critical habitat. Alternatively, the agencies could determine which listed species depend on biological resources, or have constituent elements that fall into, the taxa that may be directly or indirectly impacted by the pesticide. Then EPA would determine whether use of the pesticide overlaps the critical habitat or the occupied range of those listed species. At present, the information reviewed by EPA does not permit use of either analytical approach to make a definitive identification of species that are potentially impacted indirectly or critical habitats that is potentially impacted directly by the use of the pesticide. EPA and the Service( s) are working together to conduct the necessary analysis.

This screening level risk assessment for critical habitat provides a listing of potential biological features that, if they are constituent elements of one or more critical habitats, would be of potential concern. These correspond to the taxa identified above as being of potential concern for indirect effects and include the following: birds, small mammals, and terrestrial and semiaquatic plants. This list should serve as an initial step in problem formulation for further assessment of critical habitat impacts outlined above, should additional work be necessary Co occurrence Analysis Since the Listed Species LOCs for birds, small mammals, and terrestrial monocots and dicots are exceeded for the use of dicamba, the LOCATES was run for all taxonomic groups. For terrestrial monocots and dicots, both the Acute Risk LOCs for non listed species and the Listed Species LOCs were exceeded; consequently a potential concern arises for species with both narrow ( i. e., species that are obligates or have very specific habitat or feeding requirements) and general dependencies ( i. e., cover type requirements). Information from LOCATES, as presented in Table IV. n. below, indicates that for the corn, wheat, sugarcane and pasture/ grazing uses, several potentially affected species of birds, mammals, reptiles and plants appear to be co located with pesticide use areas. Consequently, there may be a concern for potential indirect effects to listed species dependent upon birds that consume feed items ( short and tall grasses; broadleaf plants; small and/ or large insects; and fruits, seeds, and pods) contaminated with dicamba residues; such as predatory birds and mammals. In addition, there may be a potential concern for indirect effects related to plants that require birds and/ or mammals for pollination or seed dispersal and for animals that use burrows for shelter or breeding habitat. Results of this risk assessment indicate no risk to freshwater fish and invertebrates and vascular aquatic plants; consequently, these species are not discussed here.

TABLE IV. n. Summarized Data from LOCATES # Affected Taxa by State for Corn*, Wheat, Sugarcane, Pasture and Grazing # Affected Taxa by State for Corn*

Affected States Birds Mammals Reptiles Plants Birds Mammals Reptiles Plants 77 Alabama 4 4 5 17 4 4 5 17 Arizona 8 8 2 18 8 8 2 18 Arkansas 3 3 0 4 3 3 0 4 California 16 23 8 176 15 22 8 160 Colorado 3 2 0 13 3 2 0 9 Connecticut 3 2 0 2 3 2 0 2 Delaware 2 2 0 2 2 2 0 2 Florida 9 11 10 53 9 10 9 48 Georgia 5 5 2 20 5 5 2 20 Hawaii 32 2 2 268 26 2 2 231 Idaho 2 4 0 3 2 4 0 3 Illinois 3 2 0 8 3 2 0 8 Indiana 3 2 1 2 3 2 1 2 Iowa 3 1 0 6 3 1 0 6 Kansas 4 2 0 2 4 2 0 2 Kentucky 3 3 0 10 3 3 0 10 Louisiana 6 2 3 2 6 2 2 2 Maine 3 2 0 3 3 2 0 3 Maryland 2 3 0 6 2 3 0 6 Massachusetts 3 2 1 3 3 2 1 3 Michigan 3 2 1 7 3 2 1 7 Minnesota 2 1 0 4 2 1 0 4 Mississippi 6 1 2 2 5 1 5 2 Missouri 3 2 0 8 3 2 0 8 Montana 4 3 0 2 4 3 0 2 Nebraska 4 1 0 3 4 1 0 3 Nevada 2 0 1 9 2 0 1 9 New Hampshire 1 1 0 2 1 1 0 2 New Jersey 3 2 0 5 3 2 0 5 New Mexico 6 5 1 13 6 5 1 13 New York 3 2 0 6 3 2 0 6 North Carolina 5 6 1 27 5 6 1 27 North Dakota 4 0 0 1 4 0 0 1 Ohio 2 1 2 4 2 1 2 4 78 Oklahoma 7 3 0 2 7 3 0 2 Oregon 5 1 0 13 5 1 0 9 Pennsylvania 2 2 0 2 2 2 0 2 Rhode Island 1 2 0 2 1 2 0 2 South Carolina 4 3 2 19 4 3 2 19 South Dakota 4 1 0 1 4 1 0 1 Tennessee 3 4 0 19 3 4 0 19 Texas 12 5 3 27 12 5 3 23 Utah 2 2 1 24 2 2 1 24 Vermont 1 1 0 2 1 1 0 2 Virginia 3 6 1 13 3 6 1 13 Washington 5 5 0 6 5 4 0 6 West Virginia 1 5 0 5 1 5 0 5 Wisconsin 3 1 0 6 3 1 0 6 Wyoming 1 4 0 2 1 4 0 2 * Corn use includes corn for grain ( acres), corn for silage or greenchop ( acres), popcorn ( pounds, shelled), sweet corn, sweet corn for seed ( pounds)

5. Endocrine Disrupter EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to determine whether certain substances ( including all pesticide active and other ingredients) " may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee ( EDSTAC), EPA determined that there was scientific bases for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation that the Program include evaluations of potential effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help determine whether a substance may have an effect in humans, FFDCA authority to require the wildlife evaluations. As the science develops and resources allow, screening of additional hormone systems may be added to the Endocrine Disruptor Screening Program ( EDSP). When the appropriate screening and/ or testing protocols being considered under the Agency's EDSP have been developed, dicamba and its salts may be subjected to additional screening and/ or testing to better characterize effects related to endocrine disruption. 79 C. Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Uncertainties, assumptions, and limitations associated with models Extrapolating the risk conclusions from the standard pond scenario modeled by PRZM/ EXAMS may either underestimate or overestimate the potential risks. Major uncertainties with the standard runoff scenario are associated with the physical construct of the watershed and representation of vulnerable aquatic environments for different geographic regions. The physicochemical properties ( pH, redox conditions, etc.) of the standard farm pond are based on a Georgia farm pond. These properties are likely to be regionally specific because of local hydrogeological conditions. Any alteration in water quality parameters may impact the environmental behavior of the pesticide. The farm pond represents a well mixed, static water body. Because the farm pond is a static water body ( no flow through), it does not account for pesticide removal through flow through or accidental water releases. However, the lack of water flow in the farm pond provides an environmental condition for accumulation of persistent pesticides. The assumption of uniform mixing does not account for stratification due to thermoclines ( e. g., seasonal stratification in deep water bodies). Additionally, the physical construct of the standard runoff scenario assumes a watershed: pond area ratio of 10. This ratio is recommended to maintain a sustainable pond in the Southeastern United States. The use of higher watershed: pond ratios ( as recommended for sustainable ponds in drier regions of the United States) may lead to higher pesticide concentrations when compared to the standard watershed: pond ratio.

Uncertainties and data gaps associated with the environmental fate and toxicity data There are a number of areas of uncertainty in the terrestrial and the aquatic organism risk assessments that could potentially cause an underestimation of risk. First, this assessment accounts only for exposure of non target organisms to dicamba, but not to its degradates. The risks presented in this assessment could be underestimated if the primary degradate ( DCSA) also exhibit toxicity under the conditions of use proposed on the label. Data are not available concerning the toxicity of the degradation products of dicamba. Second, the risk assessment only considers the most sensitive species tested and only considers a subset of possible use scenarios. For the aquatic organism risk assessment, there are uncertainties associated with the PRZM/ EXAMS model, input values, and scenarios including the use of surrogate scenarios, however these uncertainties cannot be quantified. The potential impacts of these uncertainties are outlined in the Aquatic Exposure and Risk Assessment and the Terrestrial Exposure and Risk Assessment sections of this document.

There is uncertainty in the environmental fate of the typical end use products ( TEPs) which contain the sodium, DMA or DGA salts of dicamba. Dissociation rates, adsorption/ desorption rates and field dissipation information are needed for TEPs to determine the persistence and mobility of the salts and their associated inert ingredients found in the TEPs. A key aspect of the field studies should include the formulated TEPs. Furthermore, these data are needed to adequately assess spray drift and volatilization.

Additional uncertainty results from the lack of information and/ or data in several components of this ecological risk assessment. First, chronic toxicity data for aquatic organisms is not available, thus the potential risk due to prolonged exposures of these species to dicamba 80 cannot be estimated. Second, toxicity data is not available concerning the acute and chronic risk to sediment dwelling benthic organisms which may contact dicamba in aquatic sediments. Third, data are unavailable concerning residue levels in foliage, insects, and seeds to accurately predict potential risks to terrestrial organisms ( birds, mammals, pollinators) which may contact dicamba residues after application. Fourth, field studies are unavailable to determine the actual extent of potential indirect effects to forest, wetland, and ecotone ( edge and riparian) habitats. 81 References Dexter, A. G., J. L. Gunsolus, and W. S. Curron. 1994. Herbicide Mode of Action and Sugarbeet Injury Symptoms. North Dakota State University Extension Service.

Grosselin, R. E. 1984. Clinical Toxicology of Commercial Products. 5th Ed. Baltimore, MD: Williams & Wilkins.

Hartzler, B. 2003. Effect of dicamba on soybean yields. Iowa State University Weed Science.

Kidd, H. and James, D. R., Eds. The Agrochemicals Handbook, Third Edition,. Royal Society of Chemistry Information Services, Cambridge, UK, 1991 ( as updated).

Proost, R. and C. Boerboom. 2004. Dicamba injury to soybeans. Nutrient and Pest Management. University of Wisconsin   Madison.

Worthing, C. R. ( ed.). 1987. The pesticide manual: A world compendium. 8th Ed. British Crop Protection Council. Croydon, England.

U. S. Department of Agriculture, Soil Conservation Service. 1990 ( Nov.) SCS/ ARS/ CES Pesticide Properties Database: Version 2.0 ( Summary). USDA  Soil Conservation Service, Syracuse, NY.

Weed Science Society of America. Herbicide Handbook, Seventh Edition. Champaign, IL, 1994. 82 APPENDIX A: Environmental Fate Studies, Chemical Structures and Some Properties of Dicamba Salts and DCSA Environmental Fate Studies Hydrolysis ( 161 1) MRID 40335501 ( MRID 40547902 is a duplicate) Study Status: Acceptable Yu, C. C. 1981. Hydrolysis of 14C Dicamba. Laboratory Project ID: 480068 34. Unpublished study performed by Velsicol Chemical Corporation, Chicago, IL, and submitted by Sandoz Crop Protection Corporation, Des Plaines, IL.

Uniformly ring labeled [ 14C] dicamba ( 3,6 dichloro o anisic acid) did not degrade significantly in aqueous buffered solutions adjusted to pH 5, 7, and 9, and distilled water treated with dicamba at 10 ppm or 100 ppm and incubated in the dark at 25 or 35 /

C for 30 days. In the test solutions incubated at 25 /

C, parent dicamba was 92.36 98.03% of the applied radioactivity at 30 days post treatment. In the test solutions incubated at 35 /

C, parent dicamba was > 92.4% of the applied radioactivity, except for the pH 7 test solution treated at 100 ppm; parent dicamba was 82.46% at 29 days post treatment. Three unidentified degradates were each < 3.54% of the applied radioactivity in any of the test systems. The material balances were 83.36 103.21%.

Aqueous Photolysis ( 161 2) MRID 42774102, Study Status: Acceptable Sen, P. K., C. C. Yu, and M. L. Ekdawi. 1993a. Dicamba: Photodegradation study in pH 7 aqueous solution. Laboratory Project No. 480065; Laboratory Report No. 19; Sponsor ID No. DP 301251. Unpublished study performed and submitted by Sandoz Agro, Inc., Des Plaines, IL.

Dicamba ( 3,6 dichloro o anisic acid) photodegraded with a half life of > 30 days in a sterile aqueous buffer solution ( pH 7) that was irradiated for 30 days with a xenon arc lamp at 25 /

C; dicamba did not degrade in the dark control sample. The registrant calculated half life was 38.1 days under continuous irradiation at 1.38 times natural sunlight at noon in the spring at 40 /

N. The major identified degradate was carbon dioxide ( maximum of 15.26% of the applied radioactivity at 30 days). Numerous other degradates were present at < 7.72% each and were not identified.

Soil Photolysis ( 161 3) MRID 42774103, Study Status: Acceptable Sen, P. K., C. C. Yu, and M. L. Ekdawi. 1993b. Dicamba: Photodegradation study on soil. Laboratory Project No. 480065; Laboratory Report No. 23; Sponsor ID No. DP 301268. Unpublished study performed and submitted by Sandoz Agro, Inc., Des Plaines, IL.

Dicamba ( 3,6 dichloro o anisic acid) slowly photodegraded ( approximately 20%) on silt loam soil that was continuously irradiated with a xenon arc lamp for 30 days at 25 /

C. Dicamba acid did not degrade in the dark control. The only identified degradate was carbon dioxide ( maximum of 3.07% of the applied at 30 days); although unidentified degradates were formed during the study, none were present at > 3.71% of the applied at any time. 83 Aerobic Soil Metabolism ( 162 1) MRID 43245207, Study Status: Acceptable Wendt, D. R. 1994. Aerobic soil metabolism of dicamba acid. Sandoz Project No. 480065 26. Unpublished study performed and submitted by Sandoz Agro. Inc., Des Plaines, IL.

Dicamba acid degraded with a half life of 6 days from silt loam soil that was moistened to 75% of 0.33 bar, treated at 2.555 µ g/ g ( 3.2 µ g/ g dry weight) with dicamba acid, and incubated aerobically in the dark at approximately 23 ° C for 365 days. CO 2 and 3,6 dichlorosalicylic acid ( 3,6 DCSA) were the primary degradates identified, at maximum concentrations of 67.3 and 17.4% of the applied, respectively. Two minor degradates, 5 hydroxy dicamba ( 5 OH) and 3,6 dichloro 2,5 dihydorxybenzoic acid ( 2,5 DiOH), were also identified at maximum concentrations of 0.8 and 2.7% of the applied, respectively. Other nonvolatile degradates were isolated at up to 3.7% of the applied but were not identified.

Anaerobic Soil Metabolism ( 162 2) MRID 43245208, Study Status: Acceptable Schmidt, J. M. 1994. Anaerobic aquatic metabolism of 14C dicamba. ABC Final Report No. 40518. Unpublished study performed by ABC Laboratories, Inc., Columbia, MO, and submitted by Sandoz Agro, Inc., Des Plaines, IL.

Dicamba acid degraded with a half life of 141 days in loam soil: pond water systems that were treated at 3.85 ppm and incubated in the dark for 12 months under anaerobic ( nitrogen gas) conditions at approximately 25 ° C. The major degradate identified in the soil: water systems was 3,6 dicholorsalicylic acid ( 3,6 DCSA) at a maximum of 61.6% of the applied. Two minor degradates, 5 hydroxy dicamba ( 5 OH dicamba) and 3,6 dichloro 2,5 dihydroxybenzoic acid ( 3,6 dichlorogentisic acid; 3,6 DCGA), were also identified ; maximum concentrations were 1.9 and 3.64% of the applied, respectively. Volatile [ 14C] residues were a maximum of 1.3% of the applied radioactivity at 12 months post treatment.

Anaerobic Aquatic Degradation ( 162 3) MRID 43245208, Study Status: Acceptable Schmidt, J. M. 1994. Anaerobic aquatic metabolism of 14C dicamba. ABC Final Report No. 40518. Unpublished study performed by ABC Laboratories, Inc., Columbia, MO, and submitted by Sandoz Agro, Inc., Des Plaines, IL.

Dicamba acid degraded with a half life of 141 days in loam soil: pond water systems that were treated at 3.85 ppm and incubated in the dark for 12 months under anaerobic ( nitrogen gas) conditions at approximately 25 ° C. The major degradate identified in the soil: water systems was 3,6 dicholorsalicylic acid ( 3,6 DCSA) at a maximum of 61.6% of the applied. Two minor degradates, 5 hydroxy dicamba ( 5 OH dicamba) and 3,6 dichloro 2,5 dihydroxybenzoic acid ( 3,6 dichlorogentisic acid; 3,6 DCGA), were also identified ; maximum concentrations were 1.9 and 3.64% of the applied, respectively. Volatile [ 14C] residues were a maximum of 1.3% of the applied radioactivity at 12 months post treatment. 84 Aerobic Aquatic Metabolism ( 162 4) MRID 43758509, Study Status: Acceptable Schmidt, J. M. 1995. Aerobic aquatic metabolism of 14C dicamba. Laboratory Study ID: 42027. Sandoz Study No. DP 301819. Unpublished study performed by ABC Laboratories, Inc., Columbia, MO; and submitted by Sandoz Agro, Inc., Des Plaines, IL.

Uniformly phenyl ring labeled [ 14C] dicamba acid, at a nominal application rate of 0.12 µ g/ mL, degraded with a registrant calculated half life of 20.2 days in aerobic flooded loam soil that was incubated in darkness at 25 ± 1 ° C for 62 days. Using non linear analysis, a slightly longer registrant calculated half life of 24.3 days was determined. In the total soil/ water system, the parent ( reviewer calculated) was 97.2 100% of the applied radioactivity at 0 3 days, decreased to 81.7% by 14 days and to 60.2% by 21 days, was 36.2% at 30 days, and was not detected by 51 days post treatment. The parent compound in the water phase was initially present at 91.9% ( 0.113 ppm) of the applied radioactivity at day 0, decreased to 54.6 75.6% by 14 21 days post treatment, and decreased to 22.4% ( 0.55ppm) by 41 days post treatment. In the soil ( Soil Extract 1), the parent compound was initially present at 7.05% ( 0.009ppm) of the applied radioactivity at day 1 ( methanol extract only), decreased to 6.10% ( 0.008ppm) by 1 day post treatment, then increase to a maximum of 8.54% ( 0.011ppm) by 3 days post treatment, and decreased to 3.66% ( 0.005ppm) by day 41 post treatment. The minor degradate 3,6 DCSA was initially observed in the water phase at 6.50% ( 0.008ppm) of the applies activity at 14 days post treatment, increased to a maximum of 8.55% ( 0.011ppm) by 30 days, and decreased to 0.813% ( 0.001ppm, based on a single replicate) by day 62. In the " Soil Extract 1" ( methanol), 3,6 DCSA was present at 1.63% ( 0.002ppm) at 30 days post treatment and < 0.001% at 62 days post treatment only. In the " Soil Extract 2" ( acidified methanol: water), the major degradate 3,6 DCSA was present at 3.26% ( 0.004ppm) at day 14 post treatment, increased to 26.0% ( 0.032ppm) by day 41, and decreased to 4.88% ( 0.001ppm) by day 62. The distribution of [ 14C] residues between the soil and water fractions was not reported, but the majority of the residues were observed in the water phase throughout the study. [ 14C] Residues in the water phase were 92.4% ( 0.114ppm) of the applied radioactivity at day 0 and decreased to 2.04% ( 0.003ppm) by 62 days post treatment. In the soil extracts, total [ 14C] residues were 7.05% ( 0.009ppm) of the applied radioactivity at day 0, increased to 43.9% ( 0.054ppm) by 41 days , and were 22.0% ( 0.027ppm) at 62 days post treatment. Nonextractable [ 14C] residues comprised 14.65% ( 0.18ppm) of the applied at 62 days post treatment. Evolved 14CO 2 accounted for 1.63% ( 0.002ppm) of the applied radioactivity at 14 days post treatment and was 53.6% ( 0.066ppm) at 62 days post treatment.

Aqueous Dissociation MRID 43288001, Study Status: Ancillary Bebel, J. C. 1994. Dissociation rate of dicamba salts. Laboratory ID Project No. 480063; Report No. 47; Sponsor ID No. DP 301564. Unpublished study performed and submitted by Sandoz Agro, Inc., Des Plaines, IL.

This is an acceptable ancillary study and can be used to provide bridging data for dicamba salts to support a reduced data set for the salts. For dicamba, there are no end use products containing the acid, thus data from studies using the sodium or potassium salt can serve to fulfill data requirements. In addition, there are no esters of the dicamba, and the other registered salts for dicamba are the dimethylamine, isopropylamine, and diglycoamine salts. This study provides 85 bridging data regarding how rapidly the salts dissociate in support of a reduced data set for the salts.

As determined by a UV spectrophotometric method, dicamba salts reached essentially 100% dissociation within 75 seconds of the time of mixing with pure water. The observed dissociation half lives in pure water, 0.1 N NaOH ( pH 13), and 0.1 N HCl ( pH 1) for all of the salts were less than 10 seconds, establishing a value 6.9 x 10 2 sec 1 as the lower limit for the dissociation fate constant for each of the salts. These data, combined with the fact that dicamba is a moderately strong acid ( pK a = 1.87) predict that when these dicamba salts are release into the environment dissociation will be rapid.

Adsorption/ Desorption in Soil ( 163 1) MRID 42774101, Study Status: Acceptable Tong, T. R. 1993a. Soil adsorption and desorption of dicamba, unaged, by the batch equilibrium method. Laboratory Project No. 480065; Laboratory Report No. 20; Sponsor ID No. DP 301215. Unpublished study performed and submitted by Sandoz Agro, Inc., Des Plaines, IL This study ( MRID 42774101) is acceptable and partially fulfills EPA Data Requirements for Registering Pesticides by providing information on the mobility ( batch equilibrium) of unaged phenyl ring labeled [ 14C] dicamba in loam, clay loam, silt loam, and sandy loam soils, and loam sediment.

Based on batch equilibrium experiments, dicamba acid was determined to be very mobile in loam, clay loam, silt loam, and sandy loam soils and a loam sediment, with Freundlich K ads values of 0.16, 0.10, 0.53. 0.07 and 0.21, respectively. Corresponding K oc values were 7.27, 3.45, 21.1, 17.5 and 17.5, respectively.

MRID 43095301, Study Status: Acceptable Tong, T. R. 1993b. Soil adsorption and desorption of the major soil metabolite of dicamba, 3,6 dichlorosalicylic acid ( 3,6 DCSA), by the batch equilibrium method. Laboratory Project No. 480065; Report No. 21; Sponsor ID No. DP 301361. Unpublished study performed and submitted by Sandoz Agro, Inc., Des Plaines, IL.

This study ( MRID 43095301) is acceptable and partially fulfills EPA Data Requirements for Registering Pesticides by providing information on the mobility ( batch equilibrium) of phenyl ringlabeled [ 14C] 3,6 DCSA in loam, clay loam, silt loam, and sandy loam soils, and loam sediment.

Based on batch equilibrium experiments, 3,6 DCSA ( 3,6 dichlorosalicylic acid), a major degradate of dicamba, was determined to be mobile in sandy loam ( Freundlich K ads value of 2.51; Ko c 628) and clay loam ( K ads 7.03; Koc 242) soils. DCSA was determined to be of low mobility in silt loam and loam soils and in loam sediment; Freundlich K ads values were 20.29, 31.50, and 35.16, respectively; corresponding Ko c values were 812, 1432, and 2930, respectively. 86 Laboratory Volatility ( 163 2) MRID 41966602, Study Status: Acceptable Yu, C. C. 1988. Addendum to report no. 480060 6 on volatility of three dicamba formulations. Laboratory Project ID: 480060 6A. Unpublished study performed and submitted by Sandoz Crop Protection Corporation, Des Plaines, IL.

The portions of this laboratory volatility study conducted with the potassium salt of dicamba and the dimethylamine salt of dicamba formulated with adjuvant are acceptable.

Dicamba ( as the potassium salt) volatilized from moist silty clay soil that was treated at a nominal field rate of 0.5 lb ai/ A ( 1.511 mg ai/ jar) with a soluble concentrate formulation fortified with [ 14C] dicamba ( radiochemical purity > 98%). Volatility rates ranged from 2.98 to 4.97 x 104 : g/ cm2/ hr; this corresponded to air concentrations of 12.6 21.0, : g/ m3. Samples were incubated for up to 96 hours on a 16 hour photoperiod under continuous air flow ( 0.1 L/ min) at 30 C and 60% relative humidity. Recovery of the applied radioactivity was 96.5%.

Dicamba ( as the dimethylamine salt formulated with the adjuvant Atplus 411f) volatilized from moist silty clay soil that was treated at a nominal field rate of 0.5 lb ai/ A ( 1.511 mg ai/ jar) with soluble concentrate formulations fortified with [ 14C] dicamba ( radiochemical purity > 98%). Volatility rates ranged from 2.91 to 4.95 x l0 4 : g/ cm2/ hr; this corresponded to air concentrations of 12.4 21.0, : g/ m3. Samples were incubated for up to 96 hours on a 16 hour photoperiod under continuous air flow ( 0.1 L/ min) at 30 ° C and 60% relative humidity. Recovery of the applied radioactivity was 70.6 88.8%.

The portion of the laboratory volatility study ( MRID 41966602; Study # 6) conducted with the dimethylamine salt of dicamba formulated without adjuvant is not acceptable because the material balance was not complete. Because the material balance was incomplete, the portion of the study using the dimethylamine salt of dicamba cannot be repaired with the submission of additional data. However, because the vapor pressure of the salt is expected to be negligible, as indicated in the registrant's response to the Dicamba Salts DCI ( EFGWB review dated 5/ 19/ 94), no additional data on the laboratory volatility of the DMA salt is required.

Terrestrial Field Dissipation ( 164 1) Studies Status: Supplemental Field dissipation studies of dicamba salts were conducted in several locations across the US in the early 1990' s ( see table below). Dicamba salts were applied to bareground plots according to labeled rates and soils were sampled for loss of parent compound and the presence of degradates over time. The major dicamba degradate in soil samples was DCSA. These studies are supplemental as Subdivision N guidelines were not fulfilled in that application rates were not verified in the field, soil sample storage stability was not verified, measurements of pan evaporation were not collected during the studies and rainfall/ irrigation amounts did not fulfill guideline requirements. 87 MRID No. Dicamba Test Substance Application Rate Study Location and Soil Type Half life ( days)

43361506 SAN 845 H ( Na salt) SAN 821 H ( DGA salt) 1.0 lb ae/ A 1.0 lb ae/ A LA, silt loam soil LA, silt loam soil 3.2 3.0 43361507 Clarity and SAN 821 H ( DGA salt) 1.0 lb ae/ A NC, loam sand soil 3.29 43651405 SAN 1214 H ( DMA salt) 2.0 lb ae/ A LA, silt loam soil 9 43651407 Clarity and SAN 821 H ( DGA salt) 2.0 lb ae/ A IN, loam soil 12.9 43651408 Banvel SGF SAN845 H ( Na salt) 2.0 lb ae/ A 2.0 lb ae/ A NC, loam sand soil NC, loam sand soil 9 9 42754101 42883202 Banvel 4.0 ( DMA salt) 1.0 lb ae/ A CA, sandy loam soil 19.8 42754102 Banvel 4.0 ( DMA salt) 1.0 lb ae/ A IN, loam soil 4.4 Octanol/ water Partition Coefficient of DCSA MRID 41966601, Study Status: Ancillary Fostiak, W., and C. C. Yu. 1989. Determination of n octanol/ water partition coefficient for 3,6 dichlorosalicylic acid ( DCSA). Laboratory Project ID: 480065 15. Unpublished study performed and submitted by Sandoz Crop Protection Corporation, Des Plaines, IL.

N octanol/ water partition coefficients ( K 0 ) for 3,6 dichloro salicylic acid ( DCSA) at two concentrations ( nominally 4.96 x 104 M and 5.67 x 10 5 M) in buffered aqueous solutions at pHs 5, 7, and 9 ranged from 0.06 to 0.58 and averaged 0.29. Because of the low K ow , DCSA is not expected to bioaccumulate in aquatic organisms. 88 TABLE A. 1. Some Physical Chemical and Other Properties of Dicamba Salts and Dicamba's Primary Degradate DCSA CAS Name and Chemical Structure CAS No Empirical Formula Molecular Weight Formulated Product Dicamba, dimethylamine salt 2300 66 5 C10H13Cl2NO3 266.1236 Banvel, Banvel CST, Gharda Dicamba, sodium salt 1982 69 0 C8H5Cl2NaO3 243.02147 Banvel II/ SGF , Albaugh Dicamba SG Dicamba, diglycoamine salt 104040 79 1 C12H17Cl2NO5 326.176 TABLE A. 1. Some Physical Chemical and Other Properties of Dicamba Salts and Dicamba's Primary Degradate DCSA 89 Dicamba, isopropylamine salt 55871 02 8 C11H15Cl2NO3 280.1504 Dicamba, potassium salt 10007 85 9 C8H5Cl2KO3 259.1217 3,6 Dichlorosalicylic acid 90 Appendix B: Aquatic Exposure Model Results Dicamba Florida Sugarcane stored as dicFLsugcanground. out Chemical: dicamba PRZM environment: FLsugarcaneC. txt modified Satday, 12 October 2002 at 16: 42: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w12844. dvf modified Wedday, 3 July 2002 at 09: 04: 30 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 4.431 4.117 3.248 2.249 1.697 0.4259 1962 37.09 32.86 21.43 10.48 7.286 1.811 1963 204 180 108 48.27 32.68 8.128 1964 37.16 32.54 20.63 10.89 7.427 1.837 1965 8.726 7.775 5.222 3.373 2.566 0.6483 1966 4.138 3.769 2.615 1.723 1.24 0.3087 1967 16.49 14.18 10.17 4.64 3.264 0.8502 1968 13.93 12.31 8.871 4.618 3.163 0.782 1969 104 95.31 57.76 25.26 17.12 4.243 1970 63.63 57.18 34.19 14.76 10 2.528 1971 38.94 34.07 22.79 12.6 8.714 2.171 1972 161 137 79.63 34.35 23.11 5.696 1973 28.77 25.17 15.56 7.219 5.087 1.268 1974 9.135 8.21 5.968 3.061 2.299 0.5771 1975 5.407 5.005 4.092 2.405 1.769 0.4433 1976 26.35 23.58 16.45 7.356 5.11 1.268 1977 126 105 55.44 24.07 16.45 4.086 1978 22.29 19.58 16 8.314 5.697 1.413 1979 164 141 85.91 40.47 27.43 6.8 1980 51.54 46.65 31.38 15.99 10.94 2.705 1981 15.5 13.54 10.96 6.403 4.621 1.154 1982 127 111 69.26 31.44 21.21 5.249 1983 4.287 3.8 2.379 1.861 1.424 0.3575 1984 57.87 50.04 30.97 13.92 9.428 2.379 1985 64.08 57.64 38.71 20.47 13.96 3.457 1986 11.06 9.857 6.752 4.417 3.221 0.8167 1987 41.6 36.66 27.16 12.41 8.736 2.172 1988 171 151 92.24 41.09 27.73 6.847 1989 212 189 117 54.23 36.73 9.095 1990 14.08 12.69 8.796 4.865 3.397 0.8443 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 212 189 117 54.23 36.73 9.095 0.0645161290322581 204 180 108 48.27 32.68 8.128 0.0967741935483871 171 151 92.24 41.09 27.73 6.847 0.129032258064516 164 141 85.91 40.47 27.43 6.8 0.161290322580645 161 137 79.63 34.35 23.11 5.696 0.193548387096774 127 111 69.26 31.44 21.21 5.249 0.225806451612903 126 105 57.76 25.26 17.12 4.243 0.258064516129032 104 95.31 55.44 24.07 16.45 4.086 0.290322580645161 64.08 57.64 38.71 20.47 13.96 3.457 0.32258064516129 63.63 57.18 34.19 15.99 10.94 2.705 91 0.354838709677419 57.87 50.04 31.38 14.76 10 2.528 0.387096774193548 51.54 46.65 30.97 13.92 9.428 2.379 0.419354838709677 41.6 36.66 27.16 12.6 8.736 2.172 0.451612903225806 38.94 34.07 22.79 12.41 8.714 2.171 0.483870967741936 37.16 32.86 21.43 10.89 7.427 1.837 0.516129032258065 37.09 32.54 20.63 10.48 7.286 1.811 0.548387096774194 28.77 25.17 16.45 8.314 5.697 1.413 0.580645161290323 26.35 23.58 16 7.356 5.11 1.268 0.612903225806452 22.29 19.58 15.56 7.219 5.087 1.268 0.645161290322581 16.49 14.18 10.96 6.403 4.621 1.154 0.67741935483871 15.5 13.54 10.17 4.865 3.397 0.8502 0.709677419354839 14.08 12.69 8.871 4.64 3.264 0.8443 0.741935483870968 13.93 12.31 8.796 4.618 3.221 0.8167 0.774193548387097 11.06 9.857 6.752 4.417 3.163 0.782 0.806451612903226 9.135 8.21 5.968 3.373 2.566 0.6483 0.838709677419355 8.726 7.775 5.222 3.061 2.299 0.5771 0.870967741935484 5.407 5.005 4.092 2.405 1.769 0.4433 0.903225806451613 4.431 4.117 3.248 2.249 1.697 0.4259 0.935483870967742 4.287 3.8 2.615 1.861 1.424 0.3575 0.967741935483871 4.138 3.769 2.379 1.723 1.24 0.3087 0.1 170.3 150 91.607 41.028 27.7 6.8423 Average of yearly averages: 2.6787 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicFLsugcanground Metfile: w12844. dvf PRZM scenario: FLsugarcaneC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 3.14 kg/ ha Application Efficiency: APPEFF .99 fraction Spray Drift DRFT .01 fraction of application rate applied to pond Application Date Date 15 04 dd/ mm or dd/ mmm or dd mm or dd mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT 92 PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

stored as dicFLsugcanaerial. out Chemical: dicamba PRZM environment: FLsugarcaneC. txt modified Satday, 12 October 2002 at 16: 42: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w12844. dvf modified Wedday, 3 July 2002 at 09: 04: 30 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 7.85 7.069 4.945 3.971 2.861 0.7139 1962 37.81 33.49 21.88 11.79 8.265 2.053 1963 198 175 105 46.89 32.57 8.098 1964 38.05 33.31 21.47 11.95 8.14 2.012 1965 9.703 8.646 5.775 4.712 3.707 0.9299 1966 7.85 7.1 5.217 3.512 2.441 0.6056 1967 16.15 13.88 9.948 4.735 4.411 1.133 1968 14.66 13 9.739 6.109 4.161 1.028 1969 102 93.54 56.68 25.66 17.61 4.365 1970 61.61 55.35 33.09 14.29 10.75 2.71 1971 38.44 33.63 23.29 13.6 9.603 2.39 1972 159 136 78.59 34.24 23.04 5.679 1973 29.17 25.52 15.76 8.576 6.072 1.511 1974 9.904 8.95 6.404 4.671 3.444 0.8604 1975 7.85 7.089 4.899 4.119 2.926 0.7297 1976 27.9 25.04 17.09 8.759 6.051 1.499 1977 122 102 54 24.43 16.86 4.187 1978 23.53 20.89 17.69 9.792 6.69 1.658 1979 160 138 83.96 39.84 27.29 6.765 1980 54.64 49.46 33.22 17.1 11.71 2.894 1981 16.64 14.53 11.45 7.775 5.612 1.399 1982 126 109 68.34 31.54 21.35 5.284 1983 8.522 7.695 5.595 3.585 2.583 0.6439 1984 56.02 48.44 29.97 13.47 10.13 2.551 1985 67.81 60.99 40.91 21.41 14.59 3.613 1986 12 10.69 7.272 5.481 4.42 1.113 1987 41.86 36.55 27.08 13.76 9.636 2.395 1988 167 147 89.85 40.47 27.69 6.838 1989 209 187 116 53.64 36.34 8.996 1990 17.45 15.73 10.67 6.401 4.428 1.099 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 209 187 116 53.64 36.34 8.996 0.0645161290322581 198 175 105 46.89 32.57 8.098 0.0967741935483871 167 147 89.85 40.47 27.69 6.838 0.129032258064516 160 138 83.96 39.84 27.29 6.765 0.161290322580645 159 136 78.59 34.24 23.04 5.679 0.193548387096774 126 109 68.34 31.54 21.35 5.284 0.225806451612903 122 102 56.68 25.66 17.61 4.365 93 0.258064516129032 102 93.54 54 24.43 16.86 4.187 0.290322580645161 67.81 60.99 40.91 21.41 14.59 3.613 0.32258064516129 61.61 55.35 33.22 17.1 11.71 2.894 0.354838709677419 56.02 49.46 33.09 14.29 10.75 2.71 0.387096774193548 54.64 48.44 29.97 13.76 10.13 2.551 0.419354838709677 41.86 36.55 27.08 13.6 9.636 2.395 0.451612903225806 38.44 33.63 23.29 13.47 9.603 2.39 0.483870967741936 38.05 33.49 21.88 11.95 8.265 2.053 0.516129032258065 37.81 33.31 21.47 11.79 8.14 2.012 0.548387096774194 29.17 25.52 17.69 9.792 6.69 1.658 0.580645161290323 27.9 25.04 17.09 8.759 6.072 1.511 0.612903225806452 23.53 20.89 15.76 8.576 6.051 1.499 0.645161290322581 17.45 15.73 11.45 7.775 5.612 1.399 0.67741935483871 16.64 14.53 10.67 6.401 4.428 1.133 0.709677419354839 16.15 13.88 9.948 6.109 4.42 1.113 0.741935483870968 14.66 13 9.739 5.481 4.411 1.099 0.774193548387097 12 10.69 7.272 4.735 4.161 1.028 0.806451612903226 9.904 8.95 6.404 4.712 3.707 0.9299 0.838709677419355 9.703 8.646 5.775 4.671 3.444 0.8604 0.870967741935484 8.522 7.695 5.595 4.119 2.926 0.7297 0.903225806451613 7.85 7.1 5.217 3.971 2.861 0.7139 0.935483870967742 7.85 7.089 4.945 3.585 2.583 0.6439 0.967741935483871 7.85 7.069 4.899 3.512 2.441 0.6056 0.1 166.3 146.1 89.261 40.407 27.65 6.8307 Average of yearly averages: 2.85844666666667 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicFLsugcanaerial Metfile: w12844. dvf PRZM scenario: FLsugarcaneC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 3.14 kg/ ha Application Efficiency: APPEFF .95 fraction Spray Drift DRFT .05 fraction of application rate applied to pond Application Date Date 15 04 dd/ mm or dd/ mmm or dd mm or dd mmm Record 17: FILTRA 94 IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

Dicamba Louisiana Sugarcane stored as dicLAsugcanground. out Chemical: dicamba PRZM environment: LAsugarcaneC. txt modified Satday, 12 October 2002 at 17: 02: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w13970. dvf modified Wedday, 3 July 2002 at 09: 05: 36 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 51.64 47.63 35.21 18.04 12.48 3.112 1962 116 104 67.83 32.48 22.08 5.485 1963 1.574 1.433 1.156 0.6783 0.4693 0.1201 1964 11.88 10.78 8.787 4.701 3.24 0.802 1965 25.63 23.35 16.09 8.03 5.538 1.377 1966 67 60.19 41.31 21.07 14.5 3.601 1967 23.29 19.54 12.18 6.897 4.737 1.178 1968 4.15 3.788 2.576 1.5 1.05 0.2614 1969 5.367 4.739 3.321 2.021 1.402 0.348 1970 51.55 46.87 33.25 17.59 12.06 2.993 1971 4.273 3.958 2.699 1.596 1.164 0.292 1972 9.164 7.907 4.734 2.642 1.846 0.4581 1973 141 128 84.44 40.36 27.51 6.817 1974 14.76 13.4 9.353 4.917 3.381 0.8421 1975 22.42 19.94 13.03 6.295 4.413 1.098 1976 12.87 11.58 7.686 3.927 2.877 0.72 1977 37.33 33.35 22.44 10.76 7.355 1.823 1978 36.53 31.86 23.07 10.51 7.289 1.814 1979 141 128 80.93 39.32 26.89 6.681 1980 17.13 14.79 11.03 5.323 3.61 0.8953 1981 4.5 4.088 2.993 1.706 1.171 0.2911 1982 13.12 12.15 8.502 4.435 3.035 0.7528 1983 21.56 19.03 11.99 6.226 4.298 1.068 1984 5.645 5.065 3.652 2.069 1.517 0.3803 1985 1.783 1.605 1.119 0.898 0.6303 0.157 1986 31.88 29.19 19.92 9.501 6.488 1.608 1987 6.973 6.214 4.042 2.15 1.56 0.3903 1988 14.75 13.45 9.568 4.964 3.42 0.8466 1989 23.06 19.54 10.54 4.565 3.086 0.7643 1990 5.936 5.476 3.917 2.127 1.463 0.3631 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 141 128 84.44 40.36 27.51 6.817 95 0.0645161290322581 141 128 80.93 39.32 26.89 6.681 0.0967741935483871 116 104 67.83 32.48 22.08 5.485 0.129032258064516 67 60.19 41.31 21.07 14.5 3.601 0.161290322580645 51.64 47.63 35.21 18.04 12.48 3.112 0.193548387096774 51.55 46.87 33.25 17.59 12.06 2.993 0.225806451612903 37.33 33.35 23.07 10.76 7.355 1.823 0.258064516129032 36.53 31.86 22.44 10.51 7.289 1.814 0.290322580645161 31.88 29.19 19.92 9.501 6.488 1.608 0.32258064516129 25.63 23.35 16.09 8.03 5.538 1.377 0.354838709677419 23.29 19.94 13.03 6.897 4.737 1.178 0.387096774193548 23.06 19.54 12.18 6.295 4.413 1.098 0.419354838709677 22.42 19.54 11.99 6.226 4.298 1.068 0.451612903225806 21.56 19.03 11.03 5.323 3.61 0.8953 0.483870967741936 17.13 14.79 10.54 4.964 3.42 0.8466 0.516129032258065 14.76 13.45 9.568 4.917 3.381 0.8421 0.548387096774194 14.75 13.4 9.353 4.701 3.24 0.802 0.580645161290323 13.12 12.15 8.787 4.565 3.086 0.7643 0.612903225806452 12.87 11.58 8.502 4.435 3.035 0.7528 0.645161290322581 11.88 10.78 7.686 3.927 2.877 0.72 0.67741935483871 9.164 7.907 4.734 2.642 1.846 0.4581 0.709677419354839 6.973 6.214 4.042 2.15 1.56 0.3903 0.741935483870968 5.936 5.476 3.917 2.127 1.517 0.3803 0.774193548387097 5.645 5.065 3.652 2.069 1.463 0.3631 0.806451612903226 5.367 4.739 3.321 2.021 1.402 0.348 0.838709677419355 4.5 4.088 2.993 1.706 1.171 0.292 0.870967741935484 4.273 3.958 2.699 1.596 1.164 0.2911 0.903225806451613 4.15 3.788 2.576 1.5 1.05 0.2614 0.935483870967742 1.783 1.605 1.156 0.898 0.6303 0.157 0.967741935483871 1.574 1.433 1.119 0.6783 0.4693 0.1201 0.1 111.1 99.619 65.178 31.339 21.322 5.2966 Average of yearly averages: 1.57798333333333 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicLAsugcanground Metfile: w13970. dvf PRZM scenario: LAsugarcaneC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual 96 Incorporation Depth: DEPI 0 cm Application Rate: TAPP 3.14 kg/ ha Application Efficiency: APPEFF .99 fraction Spray Drift DRFT .01 fraction of application rate applied to pond Application Date Date 15 04 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 Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

stored as dicLAsugcanaerial. out Chemical: dicamba PRZM environment: LAsugarcaneC. txt modified Satday, 12 October 2002 at 17: 02: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w13970. dvf modified Wedday, 3 July 2002 at 09: 05: 36 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 53.59 49.43 36.36 19.13 13.5 3.362 1962 114 103 66.87 32.36 22.37 5.555 1963 7.854 7.15 5.102 2.635 1.806 0.4513 1964 15.69 14.23 11.8 6.452 4.436 1.098 1965 29.84 27.19 18.73 9.712 6.69 1.663 1966 68.86 61.86 42.84 22 15.18 3.77 1967 28.69 24.07 14.54 7.897 5.413 1.346 1968 7.851 7.194 5.988 3.536 2.445 0.6069 1969 8.73 7.864 6.346 3.649 2.512 0.6232 1970 55.81 50.74 35.87 18.85 12.92 3.207 1971 7.852 7.277 5.354 3.772 2.655 0.6618 1972 10.78 9.304 6.444 4.416 3.044 0.7538 1973 141 128 84.43 40.41 27.57 6.832 1974 20.51 18.62 12.92 6.633 4.555 1.133 1975 24.05 21.39 14.04 7.745 5.396 1.342 1976 14.35 12.91 8.736 5.901 4.229 1.055 1977 40.31 36.07 24.28 12.07 8.24 2.042 1978 37.76 32.93 23.55 11.9 8.293 2.062 1979 139 126 79.94 38.96 26.91 6.684 1980 19.57 16.89 13.13 6.519 4.415 1.094 1981 8.609 7.822 6.756 3.615 2.473 0.6136 1982 17.43 16.1 11.87 6.27 4.283 1.062 1983 24.74 21.84 13.76 7.625 5.245 1.302 1984 7.851 7.226 5.186 4.106 2.91 0.7252 1985 7.85 7.226 5.256 2.997 2.065 0.5128 1986 35.67 32.66 22.29 11.05 7.537 1.868 1987 8.702 7.756 5.326 4.217 2.969 0.7397 1988 19.66 17.92 12.66 6.805 4.68 1.158 1989 24.63 20.85 11.25 6.214 4.189 1.037 1990 9.579 8.837 6.909 4.147 2.832 0.7022 97 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 141 128 84.43 40.41 27.57 6.832 0.0645161290322581 139 126 79.94 38.96 26.91 6.684 0.0967741935483871 114 103 66.87 32.36 22.37 5.555 0.129032258064516 68.86 61.86 42.84 22 15.18 3.77 0.161290322580645 55.81 50.74 36.36 19.13 13.5 3.362 0.193548387096774 53.59 49.43 35.87 18.85 12.92 3.207 0.225806451612903 40.31 36.07 24.28 12.07 8.293 2.062 0.258064516129032 37.76 32.93 23.55 11.9 8.24 2.042 0.290322580645161 35.67 32.66 22.29 11.05 7.537 1.868 0.32258064516129 29.84 27.19 18.73 9.712 6.69 1.663 0.354838709677419 28.69 24.07 14.54 7.897 5.413 1.346 0.387096774193548 24.74 21.84 14.04 7.745 5.396 1.342 0.419354838709677 24.63 21.39 13.76 7.625 5.245 1.302 0.451612903225806 24.05 20.85 13.13 6.805 4.68 1.158 0.483870967741936 20.51 18.62 12.92 6.633 4.555 1.133 0.516129032258065 19.66 17.92 12.66 6.519 4.436 1.098 0.548387096774194 19.57 16.89 11.87 6.452 4.415 1.094 0.580645161290323 17.43 16.1 11.8 6.27 4.283 1.062 0.612903225806452 15.69 14.23 11.25 6.214 4.229 1.055 0.645161290322581 14.35 12.91 8.736 5.901 4.189 1.037 0.67741935483871 10.78 9.304 6.909 4.416 3.044 0.7538 0.709677419354839 9.579 8.837 6.756 4.217 2.969 0.7397 0.741935483870968 8.73 7.864 6.444 4.147 2.91 0.7252 0.774193548387097 8.702 7.822 6.346 4.106 2.832 0.7022 0.806451612903226 8.609 7.756 5.988 3.772 2.655 0.6618 0.838709677419355 7.854 7.277 5.354 3.649 2.512 0.6232 0.870967741935484 7.852 7.226 5.326 3.615 2.473 0.6136 0.903225806451613 7.851 7.226 5.256 3.536 2.445 0.6069 0.935483870967742 7.851 7.194 5.186 2.997 2.065 0.5128 0.967741935483871 7.85 7.15 5.102 2.635 1.806 0.4513 0.1 109.486 98.886 64.467 31.324 21.651 5.3765 Average of yearly averages: 1.83541666666667 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicLAsugcanaerial Metfile: w13970. dvf PRZM scenario: LAsugarcaneC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 days Half life Aerobic Aquatic Metabolism kbacw 12 days Halfife Anaerobic Aquatic Metabolism kbacs 423 days Halfife 98 Aerobic Soil Metabolism asm 18 days Halfife Hydrolysis: pH 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 3.14 kg/ ha Application Efficiency: APPEFF .95 fraction Spray Drift DRFT .05 fraction of application rate applied to pond Application Date Date 15 04 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 Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

Dicamba California Alfalfa stored as dicCAalfalfaground. out Chemical: dicamba PRZM environment: CAalfalfaC. txt modified Satday, 12 October 2002 at 16: 27: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w93193. dvf modified Wedday, 3 July 2002 at 09: 04: 24 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 1.242 1.201 1.152 0.7186 0.4793 0.2208 1962 1.2 1.119 0.8442 0.488 0.3842 0.2089 1963 3.08 2.915 2.341 1.446 1.033 0.2716 1964 1.286 1.188 1.016 0.7326 0.5052 0.2133 1965 1.155 1.086 0.8441 0.4802 0.3405 0.2025 1966 1.159 1.076 0.7978 0.4291 0.3101 0.1943 1967 8.232 7.927 6.442 3.652 2.576 0.7122 1968 3.246 3.035 2.386 1.981 1.549 0.4622 1969 1.188 1.117 0.8678 0.4799 0.3589 0.2393 1970 3.3 3.143 2.728 1.51 1.007 0.4161 1971 16.6 15.65 12.3 7.316 5.183 1.537 1972 1.349 1.198 0.8161 0.5666 0.5124 0.2279 1973 1.699 1.591 1.222 0.8045 0.6424 0.2854 1974 2.705 2.508 2.04 1.555 1.091 0.3957 1975 1.255 1.197 0.9773 0.6629 0.507 0.341 1976 1.668 1.549 1.154 0.6994 0.5508 0.2851 1977 1.138 1.056 0.7853 0.552 0.3905 0.1512 1978 1.53 1.442 1.172 0.72 0.5054 0.2339 1979 1.125 1.053 0.8043 0.4357 0.3012 0.1116 1980 1.138 1.067 0.8213 0.4694 0.3302 0.1151 1981 2.894 2.704 2.064 1.157 0.796 0.2261 1982 2.511 2.28 1.643 1.145 0.9402 0.3422 1983 3.623 3.361 2.389 1.423 1.017 0.295 1984 1.121 1.053 0.8102 0.4217 0.29 0.1148 1985 1.141 1.054 0.7699 0.4409 0.3395 0.1903 99 1986 3.295 3.16 1.791 0.6621 0.4416 0.2112 1987 4.068 3.697 2.539 1.759 1.375 0.6274 1988 9.521 8.956 6.884 3.88 2.733 0.6949 1989 2.013 1.845 1.311 0.8854 0.643 0.2079 1990 3.311 3.069 2.239 1.572 1.182 0.3037 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 16.6 15.65 12.3 7.316 5.183 1.537 0.0645161290322581 9.521 8.956 6.884 3.88 2.733 0.7122 0.0967741935483871 8.232 7.927 6.442 3.652 2.576 0.6949 0.129032258064516 4.068 3.697 2.728 1.981 1.549 0.6274 0.161290322580645 3.623 3.361 2.539 1.759 1.375 0.4622 0.193548387096774 3.311 3.16 2.389 1.572 1.182 0.4161 0.225806451612903 3.3 3.143 2.386 1.555 1.091 0.3957 0.258064516129032 3.295 3.069 2.341 1.51 1.033 0.3422 0.290322580645161 3.246 3.035 2.239 1.446 1.017 0.341 0.32258064516129 3.08 2.915 2.064 1.423 1.007 0.3037 0.354838709677419 2.894 2.704 2.04 1.157 0.9402 0.295 0.387096774193548 2.705 2.508 1.791 1.145 0.796 0.2854 0.419354838709677 2.511 2.28 1.643 0.8854 0.643 0.2851 0.451612903225806 2.013 1.845 1.311 0.8045 0.6424 0.2716 0.483870967741936 1.699 1.591 1.222 0.7326 0.5508 0.2393 0.516129032258065 1.668 1.549 1.172 0.72 0.5124 0.2339 0.548387096774194 1.53 1.442 1.154 0.7186 0.507 0.2279 0.580645161290323 1.349 1.201 1.152 0.6994 0.5054 0.2261 0.612903225806452 1.286 1.198 1.016 0.6629 0.5052 0.2208 0.645161290322581 1.255 1.197 0.9773 0.6621 0.4793 0.2133 0.67741935483871 1.242 1.188 0.8678 0.5666 0.4416 0.2112 0.709677419354839 1.2 1.119 0.8442 0.552 0.3905 0.2089 0.741935483870968 1.188 1.117 0.8441 0.488 0.3842 0.2079 0.774193548387097 1.159 1.086 0.8213 0.4802 0.3589 0.2025 0.806451612903226 1.155 1.076 0.8161 0.4799 0.3405 0.1943 0.838709677419355 1.141 1.067 0.8102 0.4694 0.3395 0.1903 0.870967741935484 1.138 1.056 0.8043 0.4409 0.3302 0.1512 0.903225806451613 1.138 1.054 0.7978 0.4357 0.3101 0.1151 0.935483870967742 1.125 1.053 0.7853 0.4291 0.3012 0.1148 0.967741935483871 1.121 1.053 0.7699 0.4217 0.29 0.1116 0.1 7.8156 7.504 6.0706 3.4849 2.4733 0.68815 Average of yearly averages: 0.33462 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicCAalfalfaground Metfile: w93193. dvf PRZM scenario: CAalfalfaC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr 100 Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ ha Application Efficiency: APPEFF .99 fraction Spray Drift DRFT .01 fraction of application rate applied to pond Application Date Date 15 04 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 Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

stored as dicCAalfalfaerial. out Chemical: dicamba PRZM environment: CAalfalfaC. txt modified Satday, 12 October 2002 at 16: 27: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w93193. dvf modified Wedday, 3 July 2002 at 09: 04: 24 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 1.242 1.201 1.152 0.7186 0.4793 0.2208 1962 1.2 1.119 0.8442 0.488 0.3842 0.2089 1963 3.08 2.915 2.341 1.446 1.033 0.2716 1964 1.286 1.188 1.016 0.7326 0.5052 0.2133 1965 1.155 1.086 0.8441 0.4802 0.3405 0.2025 1966 1.159 1.076 0.7978 0.4291 0.3101 0.1943 1967 8.232 7.927 6.442 3.652 2.576 0.7122 1968 3.246 3.035 2.386 1.981 1.549 0.4622 1969 1.188 1.117 0.8678 0.4799 0.3589 0.2393 1970 3.3 3.143 2.728 1.51 1.007 0.4161 1971 16.6 15.65 12.3 7.316 5.183 1.537 1972 1.349 1.198 0.8161 0.5666 0.5124 0.2279 1973 1.699 1.591 1.222 0.8045 0.6424 0.2854 1974 2.705 2.508 2.04 1.555 1.091 0.3957 1975 1.255 1.197 0.9773 0.6629 0.507 0.341 1976 1.668 1.549 1.154 0.6994 0.5508 0.2851 1977 1.138 1.056 0.7853 0.552 0.3905 0.1512 1978 1.53 1.442 1.172 0.72 0.5054 0.2339 1979 1.125 1.053 0.8043 0.4357 0.3012 0.1116 1980 1.138 1.067 0.8213 0.4694 0.3302 0.1151 1981 2.894 2.704 2.064 1.157 0.796 0.2261 1982 2.511 2.28 1.643 1.145 0.9402 0.3422 101 1983 3.623 3.361 2.389 1.423 1.017 0.295 1984 1.121 1.053 0.8102 0.4217 0.29 0.1148 1985 1.141 1.054 0.7699 0.4409 0.3395 0.1903 1986 3.295 3.16 1.791 0.6621 0.4416 0.2112 1987 4.068 3.697 2.539 1.759 1.375 0.6274 1988 9.521 8.956 6.884 3.88 2.733 0.6949 1989 2.013 1.845 1.311 0.8854 0.643 0.2079 1990 3.311 3.069 2.239 1.572 1.182 0.3037 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 16.6 15.65 12.3 7.316 5.183 1.537 0.0645161290322581 9.521 8.956 6.884 3.88 2.733 0.7122 0.0967741935483871 8.232 7.927 6.442 3.652 2.576 0.6949 0.129032258064516 4.068 3.697 2.728 1.981 1.549 0.6274 0.161290322580645 3.623 3.361 2.539 1.759 1.375 0.4622 0.193548387096774 3.311 3.16 2.389 1.572 1.182 0.4161 0.225806451612903 3.3 3.143 2.386 1.555 1.091 0.3957 0.258064516129032 3.295 3.069 2.341 1.51 1.033 0.3422 0.290322580645161 3.246 3.035 2.239 1.446 1.017 0.341 0.32258064516129 3.08 2.915 2.064 1.423 1.007 0.3037 0.354838709677419 2.894 2.704 2.04 1.157 0.9402 0.295 0.387096774193548 2.705 2.508 1.791 1.145 0.796 0.2854 0.419354838709677 2.511 2.28 1.643 0.8854 0.643 0.2851 0.451612903225806 2.013 1.845 1.311 0.8045 0.6424 0.2716 0.483870967741936 1.699 1.591 1.222 0.7326 0.5508 0.2393 0.516129032258065 1.668 1.549 1.172 0.72 0.5124 0.2339 0.548387096774194 1.53 1.442 1.154 0.7186 0.507 0.2279 0.580645161290323 1.349 1.201 1.152 0.6994 0.5054 0.2261 0.612903225806452 1.286 1.198 1.016 0.6629 0.5052 0.2208 0.645161290322581 1.255 1.197 0.9773 0.6621 0.4793 0.2133 0.67741935483871 1.242 1.188 0.8678 0.5666 0.4416 0.2112 0.709677419354839 1.2 1.119 0.8442 0.552 0.3905 0.2089 0.741935483870968 1.188 1.117 0.8441 0.488 0.3842 0.2079 0.774193548387097 1.159 1.086 0.8213 0.4802 0.3589 0.2025 0.806451612903226 1.155 1.076 0.8161 0.4799 0.3405 0.1943 0.838709677419355 1.141 1.067 0.8102 0.4694 0.3395 0.1903 0.870967741935484 1.138 1.056 0.8043 0.4409 0.3302 0.1512 0.903225806451613 1.138 1.054 0.7978 0.4357 0.3101 0.1151 0.935483870967742 1.125 1.053 0.7853 0.4291 0.3012 0.1148 0.967741935483871 1.121 1.053 0.7699 0.4217 0.29 0.1116 0.1 7.8156 7.504 6.0706 3.4849 2.4733 0.68815 Average of yearly averages: 0.33462 Inputs generated by pe4. pl  8 August 2003 Data used for this run: Output File: dicCAalfalfaerial Metfile: w93193. dvf PRZM scenario: CAalfalfaC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments 102 Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ ha Application Efficiency: APPEFF .99 fraction Spray Drift DRFT .01 fraction of application rate applied to pond Application Date Date 15 04 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 Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

Dicamba Minnesota Alfalfa stored as dicMNalfalfaground. out Chemical: dicamba PRZM environment: MNalfalfaC. txt modified Satday, 12 October 2002 at 17: 04: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w14914. dvf modified Wedday, 3 July 2002 at 09: 05: 52 Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 1.933 1.881 1.615 1.142 0.8461 0.2174 1962 1.122 1.09 0.9594 0.626 0.4583 0.1183 1963 1.121 1.083 0.9369 0.6677 0.5022 0.1294 1964 11.84 11.39 9.41 5.721 4.129 1.053 1965 1.129 1.09 0.9403 0.6493 0.4853 0.1308 1966 1.209 1.177 1.075 0.8073 0.6045 0.1564 1967 14.66 14.24 12.89 9.182 6.936 1.818 1968 4.514 4.357 3.727 2.564 1.948 0.5167 1969 1.125 1.079 0.9062 0.723 0.5731 0.153 1970 3.268 3.167 2.749 1.887 1.4 0.3598 1971 1.123 1.084 0.9604 0.6575 0.4847 0.1267 1972 1.121 1.088 0.9537 0.708 0.5262 0.1363 1973 1.121 1.087 0.9539 0.6491 0.4823 0.1251 1974 1.126 1.089 1.023 0.7557 0.5661 0.1459 1975 2.95 2.875 2.552 1.713 1.244 0.3171 103 1976 1.122 1.08 0.9197 0.6037 0.441 0.1134 1977 15.78 14.38 9.994 5.357 3.876 1.007 1978 1.13 1.095 0.9545 0.6162 0.4501 0.1202 1979 4.474 4.34 3.806 2.693 2.004 0.5164 1980 1.124 1.078 0.9046 0.5603 0.4075 0.1061 1981 1.223 1.17 0.928 0.8227 0.6705 0.179 1982 1.122 1.089 0.9554 0.6449 0.4849 0.127 1983 1.121 1.089 0.9615 0.7118 0.5344 0.1378 1984 1.121 1.082 0.931 0.6216 0.4555 0.1169 1985 1.121 1.08 0.9204 0.7544 0.582 0.1541 1986 4.765 4.59 3.996 2.59 1.9 0.4891 1987 1.124 1.075 0.891 0.7296 0.5524 0.1446 1988 1.121 1.082 0.9281 0.57 0.404 0.102 1989 1.121 1.083 0.9353 0.7916 0.615 0.1593 1990 1.121 1.085 1.001 0.7049 0.52 0.1343 Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 15.78 14.38 12.89 9.182 6.936 1.818 0.0645161290322581 14.66 14.24 9.994 5.721 4.129 1.053 0.0967741935483871 11.84 11.39 9.41 5.357 3.876 1.007 0.129032258064516 4.765 4.59 3.996 2.693 2.004 0.5167 0.161290322580645 4.514 4.357 3.806 2.59 1.948 0.5164 0.193548387096774 4.474 4.34 3.727 2.564 1.9 0.4891 0.225806451612903 3.268 3.167 2.749 1.887 1.4 0.3598 0.258064516129032 2.95 2.875 2.552 1.713 1.244 0.3171 0.290322580645161 1.933 1.881 1.615 1.142 0.8461 0.2174 0.32258064516129 1.223 1.177 1.075 0.8227 0.6705 0.179 0.354838709677419 1.209 1.17 1.023 0.8073 0.615 0.1593 0.387096774193548 1.13 1.095 1.001 0.7916 0.6045 0.1564 0.419354838709677 1.129 1.09 0.9615 0.7557 0.582 0.1541 0.451612903225806 1.126 1.09 0.9604 0.7544 0.5731 0.153 0.483870967741936 1.125 1.089 0.9594 0.7296 0.5661 0.1459 0.516129032258065 1.124 1.089 0.9554 0.723 0.5524 0.1446 0.548387096774194 1.124 1.089 0.9545 0.7118 0.5344 0.1378 0.580645161290323 1.123 1.088 0.9539 0.708 0.5262 0.1363 0.612903225806452 1.122 1.087 0.9537 0.7049 0.52 0.1343 0.645161290322581 1.122 1.085 0.9403 0.6677 0.5022 0.1308 0.67741935483871 1.122 1.084 0.9369 0.6575 0.4853 0.1294 0.709677419354839 1.121 1.083 0.9353 0.6493 0.4849 0.127 0.741935483870968 1.121 1.083 0.931 0.6491 0.4847 0.1267 0.774193548387097 1.121 1.082 0.9281 0.6449 0.4823 0.1251 0.806451612903226 1.121 1.082 0.928 0.626 0.4583 0.1202 0.838709677419355 1.121 1.08 0.9204 0.6216 0.4555 0.1183 0.870967741935484 1.121 1.08 0.9197 0.6162 0.4501 0.1169 0.903225806451613 1.121 1.079 0.9062 0.6037 0.441 0.1134 0.935483870967742 1.121 1.078 0.9046 0.57 0.4075 0.1061 0.967741935483871 1.121 1.075 0.891 0.5603 0.404 0.102 0.1 11.1325 10.71 8.8686 5.0906 3.6888 0.95797 Average of yearly averages: 0.303703333333333 Inputs generated by pe4. pl  8 August 2003 104 Data used for this run: Output File: dicMNalfalfaerial Metfile: w14914. dvf PRZM scenario: MNalfalfaC. txt EXAMS environment file: pond298. exv Chemical Name: dicamba Description Variable Name Value Units Comments Molecular weight mwt 221.04 g/ mol Henry's Law Const. henry 1.6e 09 atm m^ 3/ mol Vapor Pressure vapr 3.41e 05 torr Solubility sol 6100 mg/ L Kd Kd mg/ L Koc Koc 13.4 mg/ L Photolysis half life kdp 38.1 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 7 0 days Half life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ ha Application Efficiency: APPEFF .99 fraction Spray Drift DRFT .01 fraction of application rate applied to pond Application Date Date 15 04 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 Pond Flag for runoff calc. RUNOFF none, monthly or total( average of entire run)

stored as dicMNalfalfaaerial. out Chemical: dicamba PRZM environment: MNalfalfaC. txt modified Satday, 12 October 2002 at 17: 04: 00 EXAMS environment: pond298. exv modified Thuday, 24 July 2003 at 10: 02: 00 Metfile: w14914. dvf modified Wedday, 3 July 2002 at 09: 05: 52 Water segment concentrations ( ppb)