## Ecological Risk Assessment for Use of S-Metolachlor (PC 108800)

On Pumpkins and Winter Squash (DP324973, DP327861) May 2006

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### Table of Contents

1. Executive Summary.................................................................................................... 5

1.1 Nature of Stressor ............................................................................................... 5

1.2 Potential Risk...................................................................................................... 5 1.3 Endangered Species Assessment ........................................................................ 7

2. Problem Formulation ................................................................................................ 11
2.1 Stressor Description.......................................................................................... 11 2.2 Environmental Fate Summary .......................................................................... 12

2.3 Mode of Action................................................................................................. 13

2.4 Use Characterization......................................................................................... 14 2.5.1 Ecosystems Potentially at Risk ................................................................. 15 2.5.2 Ecological Effects ..................................................................................... 16 2.7 Risk Hypotheses................................................................................................ 18 2.8 Key Uncertainties and Information Gaps ......................................................... 18

3. Exposure Assessment................................................................................................ 19
3.1 Label Application Rates and Intervals.............................................................. 19 3.2 Aquatic Exposure.............................................................................................. 19 3.2.1 PRZM-EXAMS Modeling Inputs and Scenario Selection ....................... 19 3.2.2 PRZM-EXAMS Modeling Output............................................................ 20 3.2.3 GENEEC Modeling for Degradates.............................................................. 21 3.3 National Surface Water Monitoring Data Assessment ..................................... 22 3.5 Bird and Mammal Exposure (TREX)............................................................... 23 3.6 Terrestrial Plant Exposure (TerrPlant & AgDrift)............................................ 24

3.6.1 TerrPlant ................................................................................................... 24 3.6.2 AgDrift...................................................................................................... 25

4. Effects Assessment ................................................................................................... 26
4.1 Aquatic Hazard Summary................................................................................. 26

4.3 Avian and Small Mammal Guideline Data....................................................... 33

4.4 Terrestrial Insect Data....................................................................................... 34

4.5 Terrestrial Animal Data from ECOTOX .......................................................... 34

4.7 Incident Database Review................................................................................. 34

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### 5. Risk Estimation......................................................................................................... 34
5.1 Aquatic RQ Summary....................................................................................... 35 5.2 Terrestrial RQ Summary................................................................................... 36

5.2.1 Terrestrial Plants ....................................................................................... 36

5.2.1.1 TerrPlant ................................................................................................... 36 5.2.1.2 AgDrift...................................................................................................... 38 5.2.2 Avian RQ Summary.................................................................................. 38 5.2.3 Small Mammal RQ Summary................................................................... 39

5.2.4. Terrestrial Insects...................................................................................... 39

6. Risk Description........................................................................................................ 40
6.1 Aquatic Risk...................................................................................................... 40 6.1.2 Aquatic Animals ....................................................................................... 40

6.2 Terrestrial Risk.................................................................................................. 41

6.2.1 Plants......................................................................................................... 41 6.2.2 Animals (Birds, Mammals, Insects).......................................................... 41 6.3 Endangered Species .......................................................................................... 42 6.3.1 Aquatic Endangered Species..................................................................... 42

6.3.2 Plants......................................................................................................... 43 6.3.3 Birds, Reptiles & Amphibians .................................................................. 45

6.3.4 Mammals................................................................................................... 48 6.3.5 Probability of Individual Effects............................................................... 49

References......................................................................................................................... 50

ECOTOX References....................................................................................................... 51

Appendix A Aquatic Exposure PRZM-EXAMS Output ........................................... 52

Appendix B Terrestrial Animals Exposure TREX Output ........................................ 53

Appendix C Terrestrial Plant Exposure Output (TerrPlant, AgDrift) .................... 54

Appendix D Aquatic RQ Calculations ......................................................................... 55

Appendix E Incident Database Report EIIS Output .................................................. 56

Appendix F Risk Quotient Method and Levels of Concern ....................................... 57

Appendix G Threatened and Enda ngered Species LOCATES Output .................... 58

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### List of Tables

Table 1 Endangered Species Occurring in the Same County as Proposed Crops .............. 7 Table 2 Summary of Direct and Indirect Effects............................................................. 10 Table 3 Label Application Rates....................................................................................... 19 Table 4 Input Parameters for PRZM-EXAMS Modeling................................................. 20

Table 5 PRZM-EXAMS EECs ........................................................................................ 21 Table 6 GENEEC Input Parameters for Degradates........................................................ 21 Table 7 EECs for Degradates........................................................................................... 22

Table 8 Bird Dose Estimates............................................................................................. 23

Table 9 Mammal Dose Estimates ..................................................................................... 24 Table 10 Terrestrial Plant Exposure (TerrPlant)............................................................... 25 Table 11 Terrestrial Plant Expos ure (AgDrift, Ground spray) ......................................... 25 Table 12 Acute Aquatic Data from Registrant-submitted Studies.................................... 28 Table 13 Chronic Aquatic Data from Registrant-submitted Studies ................................ 28 Table 14 Acute Aquatic Degradate Data from Registrant-submitted Studies .................. 29 Table 15 Aquatic Data from ECOTOX ............................................................................ 30

Table 16 Terrestrial Plant Guideline Data ........................................................................ 32

Table 17 Terrestrial Plant Data from ECOTOX............................................................... 32

Table 18 Avian and Small Mammal Guideline Data from Acute Studies........................ 33

Table 19 Avian and Small Mammal Guideline Data from Chronic Studies .................... 33 Table 20 Summary of Aquatic RQs for S-metolachlor .................................................... 35 Table 21 Summary of Aquatic RQs for Degradates ......................................................... 36

Table 22 Terrestrial Plant Risk Quotients Based on TerrPlant......................................... 37 Table 23 Required Distance from Ap plication to Fall Below LOC ................................. 38 Table 24 Avian RQ Summary........................................................................................... 38 Table 25 Small Mammal RQ Summary............................................................................ 39 Table 26 Endangered Plants by State and Crop................................................................ 44 Table 27 Endangered birds potentially at risk from s-metolachlor................................... 46 Table 28 Endangered reptiles and amphibians po tentially at risk from S-metolachlor.... 47 Table 29 Endangered mammals potentially at risk from S-metolachlor .......................... 48

Table of Figures

Figure 1 Chemical structure of metol achlor and all possible stereochemical

conformations ........................................................................................................... 11 Figure 2 Chemical structures for S-metolachlor degradates............................................ 12 Figure 3 Conceptual model for S-metolachlor effects..................................................... 17

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### 1. Executive Summary

This ecological risk assessment evaluates the use of the herbicide S-metolachlor (PC108800) on the minor crops of pumpkins and winter squash. Based on the proposed label addition, the existing label (D ual II Magnum®, EPA Reg. #100-818), and communications with the regist rant (Syngenta), the model parameters included a yearly maximum rate of 1.33 pt/A/year of form ulated product (1.27 lb ai/A/year), and application via ground spray. A 400 ft buffer from sensitive plants is noted in the label. Application rates vary dependent on soil organic matter. A higher rate (1.33 pt/A formulated product, equivalent to 1.27 lb ai /A) is used on soils containing >3% organic matter, and a lower rate of 1.0 pt/A formulat ed product (equivalent to 0.95 ai/A) for soils with less organic matter. Throughout the a ssessment, both rates are evaluated for all endpoints.

1.1 Nature of Stressor

S-metolachlor is a chloroactanilide herbicide, classified as a seedling shoot growth inhibitor. It inhibits biosynt hesis in plants, although the sp ecific biochemical target has not been identified. It is slightly toxic to practically nontoxic to birds, and moderately toxic to fish. Two degradates, the ethane sulfonic acid (ESA) and the oxanilic acid (OA) have been identified as potentially of toxicological concern. OA is s lightly toxic to both fish and aquatic invertebrates. ESA is slig htly toxic to fish, a nd practically nontoxic to aquatic invertebrates. Neither is as active against aquatic or terrestrial plants as the parent. S-metolachlor is pers istent and highly mobile in soil. S-metolachlor and the major degradates OA and ESA have been dete cted in surface and groundwater, especially in the Midwest, where it is us ed extensively for corn.

1.2 Potential Risk

Terrestrial Plants Non-target organisms most at risk from S-metolachlor use are terrestrial plants near the use site(s), especially herbaceous plants that are newly emerging. Plants are less likely to be affected when they are mature or actively growing, and are exposed to S-metolachlor via foliar contact. Non-endangered plant a nd endangered plant LOCs are exceeded by at least an order of magnitude and sometimes up to three orders of magnitude in any areas receiving runoff from treated fi elds. Based on spray drift alon e, risk quotients (RQs) for plants fall below the non-endangered speci es level of concern (LOC) beyond a downwind

distance from the treated field of 250-300 ft (based on the more sensitive seedling emergence endpoint). This potential zone of impact is within the required 400-ft buffer established on the label for application distan ces from sensitive plants. However, the endangered species acute risk LOC is still ex ceeded at 600 ft away from the application point, based on AgDrift modeli ng. Clearance distances for mature plants (based on vegetative vigor endpoints) are considerab ly less, ranging from 10-60 ft for the nonendangered plants LOC and at approximatel y 100 ft for the endangered plants. These clearance distances do not apply if the area receives runoff from the field.

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### Plant toxicity data was available for the metolachlor degradates OA and ESA. No significant effects are expected from the de gradates, based on the toxicity data and estimated environmental concentrations (EECs).

Disruption of plant communities near the use si te could have effects on the diversity and abundance of wildlife inhabiting these areas. The composition and health of plant communities determine quantity and type of w ildlife present. Plant communities serve

both as shelter and food.

Terrestrial Animals

There were no acute risk or chronic risk c oncerns for direct effects to non-endangered birds. However, acute endangered species LO Cs for small insectivorous and herbivorous birds were exceeded at the higher applic ation rate (1.27 lb ai/A) and for small

herbivorous birds at the lower a pplication rate (0.95 lb ai/A). Acute RQs for birds ranged from <0.01 (frugivores and granivores) to 0.19 (small herbivorous birds, 1.27 lb ai/A application rate).

There were no acute non-endangered or endangere d species acute risk concerns for small

mammals based on the conditions modeled. The chronic dose-based RQs ranged from 1.70 to 8.81, which exceed the chronic risk LO C of 1). Chronic dietary-based RQs for these organisms ranged from 0.05 to 1.02. The RQ for small mammals consuming short grass exceeded the LOC at the higher applicati on rate. Chronic effect s noted in guideline studies were reduced weights of offspring in the F 1 

### and F 2 

### generations. These were the only effects noted, and occurred at the highest treatment level. Reduced offspring weight, especially for organisms in a natu ral environment, is often correlated with reduced survivability of individuals.

Aquatic Plants and Animals

In the aquatic environment, the primary producti vity of the ecosystem is most likely to be affected. Acute risk and endangered species acute risk RQs exceeded the LOCs for the most sensitive freshwater non-vascular plant (a green alga, Selenastrum capricornutum )

in all scenarios evaluated. Freshwater vascul ar plants appear to be less sensitive to the effects of S-metolachlor. Endangered species acute risk RQs exceeded the LOCs for the freshwater vascular plant ( Lemna gibba ) in all scenarios evaluated and RQs for nonendangered plants exceeded the LOC in scen arios where there is low organic matter (<3%) in the soil. The saltwater non-vascular plant (a diatom, Skeletonema costatum ) was less sensitive than the green alga and there were no exceedences of the acute risk LOC, although aquatic concentrations from the uses in California and Florida were high enough that the endangered species acute risk LOC for saltwater aquatic plants was

exceeded.

In aquatic systems, the importance of pr imary productivity occurring within a given ecosystem varies widely. However, differentia l selection pressure for algal species could

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### have cascading effects up the food chain. Re duction in the numbers of green algae, which are generally considered a good food source for herbiv orous aquatic invertebrates (such as Daphnia ), with a concurrent increase in less palatable algal genera, such as bluegreen algae, could cause shifts in aquatic co mmunity composition, and/or result in overall reduction in biomass in the system. Asse ssing the likelihood or magnitude of such an effect on specific systems is beyond the scope of this document. Additionally, the presence and/or effectiveness of compensato ry mechanisms within certain environments

is unknown.

There were no risk concerns for acute dire ct effects to endang ered or non-endangered aquatic animals in freshwater or saltwat er environments. The highest aquatic concentrations of S-metolachlo (1-in-10 y ear peak 35.1 ppb) were associated with the California scenario, although it wa s the lower application rate. For this scenario, the acute risk RQs for the aquatic animals were ranged from <0.01 to 0.02. Chronic RQs for aquatic invertebrates and fish ranged from 0.01 to 0.97. The chronic RQ for freshwater fish (0.97) approached, but did not exceed the LOC. The other chronic RQs were significantly lower (0.01-0.03).

1.3 Endangered Species Assessment

As an initial screening to determine what endangered species may be affected by proposed uses of S-metolachlor, EFED us ed LOCATES (Ver 2.10.0) to determine what species are known to occur in counties where the proposed crops are grown. All taxa

were searched and a total of 1175 species are present in counties where pumpkins and squash are grown. Of all species identified, 56% are plants. A total of 830 (71%) could be directly affected, and 345 (29%) could be indirectly affected vi a habitat modification

or food chain effects. Table 1 shows the number of unique species ( i.e., species are counted only once, even if they are affected in multiple counties) which may be directly affected by use of S-metolachlor, based on exceedences of the endangered species LOCs. Aquatic organisms, which may be indirectly a ffected, are not included in the table but are listed in Appendix G.

Table 1 Endangered Species Occurring in the Same County as Proposed Crops

Taxa Pumpkins Winter Squash All Uses

Monocots 58 61 61

Dicots 520 568 576
Other Plants 1 19 21 22 Amphibians 12 16 16

Birds 70 71 71 Reptiles 26 29 29

Mammals 51 55 55

1 Consists of conifers and cycads, ferns and allies, and lichens



### Table 2 presents a summary of potential direct and indirect effects of S-metolachlor on endangered species.

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### Direct Effects -Plants S-metolachlor is primarily a germination inhibi tor, thus the endangered plants most likely to be affected are ones in the process of ge rminating. Drift deposition of the herbicide on mature or actively growing plants appears unl ikely to cause much effect. The TerrPlant model, which estimates exposure based on both runoff and drift, indicates that plants (both monocots and dicots) in ar eas receiving runoff from the treat ed field are likely to be affected. Total loading endangered species RQs (runoff plus drift) ranged from 57 to

2328.

A significant number of endangered plants o ccur in counties where pumpkins and squash are grown, especially the states of Hawaii, Ca lifornia, and Florida. An important aspect of determining the risk to these plants is their proximity to the use site(s).

Direct Effects – Animals

EFED evaluates risk to terre strial organisms based on inge stion of contaminated food items. The amount of pesticide deposited on the food item varies dependent on its size and surface area. The dose the organism ingest s is calculated using allometric equations. By sorting the animals identified by LOCATES into diet and size classes that correlate with the output from the TREX model, a refi ned list of animals poten tially at risk can be

created. Diet and size information wa s obtained from NatureServe database.

Using this method, a total of 26 endangered bird s were identified as po tentially at risk.

All were small insectivorous birds, and 13 of them occu r only in Hawaii. Species

information is shown in Table 27 . Potential risk to reptiles and terrestrial phase amphibians is determined based on bird data. Reptiles and amphibians are not sorted by size class, as allometric e quations derived for warm-bloode d organisms are not expected to be applicable. A total of 26 herbivor ous and insectivorous reptiles and amphibians were identified as potentially at risk (

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### Table 28 ). Herbivorous and insectivorous mammal s of all size classes exceeded chronic risk LOCs. A total of 12 species ( Table 29 ) were identified as potentially at risk.

Indirect Effects – Plants Pesticide-mediated indirect effects to plants are usually the loss of an important pollinator or dispersal species. Given the relatively lo w toxicity of s-metolachlor to animals in general, the likelihood of these types of eff ects appears to be low. Some endangered plant species may require the presence of othe r non-endangered plant species to create a

suitable habitat. The effects of s-metolachlor on plant habitat could c onstitute an indirect effect, but without detailed information on th e plant’s life history and distribution, EFED is unable to even qualitatively ev aluate this type of effect.

Indirect Effects - Animals The most likely indirect effect on animals is modification of habitat as a result of damage to plants. The habitat modification could in clude reduced food supply, reduced locations for nesting or burrowing, and/or reduced cover for predator avoidance. EFED is currently unable to evalua te the likelihood or magnit ude of such an effect.

9Table 2 Summary of Direct and Indirect Effects

Evaluation Organism LOCATES Category Direct Effects Indirect Effects

Monocots Monocots Other 1

Dicots Dicots Yes
Effects at both proposed application
rates of 1.33 and 1.0 pt/A 2 Possible
Effects on birds or
mammals could affect pollinator or dispersal species

Birds Reptiles

Birds Terrestrial
Phase Amphibians Yes Acute effects,
herbivores and insectivores, small size class, at 1.33 and 1.0 pt/A 2

Mammals Mammals Yes Chronic effects,
herbivores and invertivores, all size classes, at 1.33 and 1.0 pt/A 2 Possible Modification of plant community could affect
food and shelter

FW Aquatic
Plants FW Aquatic
Plants Yes
LOC exceedences for both algae and vascular plants SW Aquatic
Plants SW Aquatic
Plants Yes
LOC exceedences
FW Crustacea No

FW Bivalves No FW Aquatic
Invertebrates FW Gastropods No

FW Fish No
FW Fish Aquatic Phase Amphibians No

SW Crustacea No

SW Bivalves No SW Aquatic
Invertebrates SW Gastropods No
SW Fish SW Fish No Possible Modification of primary productivity in the system could affect survival or fecundity of
individuals. Modification of riparian vegetation could affect

water temperature, allochthonous input, sedimentation, or bank stability

1 Cycads, Conifers, Fern Allies. These genera have no direct corollary test organism, and have been evaluated based on the most sensitive plant endpoint.

2 formulated product



### 10

### 2. Problem Formulation

Problem formulation provides a strategic framework for the risk assessment. By identifying the important components of the problem, it focuses the assessment on the most relevant chemical properties, exposure routes, and endpoints.

2.1 Stressor Description

S-metolachlor is a chloroactanilide herbicide, classified as a seedling shoot growth inhibitor. Metolachlor has four stable stereoisomers ( Figure 1 ), because there is one chiral center (producing S- and R- enantiome rs) and a chiral axis (U.S. PTO 1991). The product registered as S-metolachlor (PC108800) consists of 88% S-enantiomer and 12% R-enantiomer. It is a separate registrati on than the product know n as metolachlor orracemic metolachlor (PC 108801), which consists of 50% S-enantiomer and 50% Renantiomer. The S-enantiomer is more herbicidally active. The Agency has determined that both environmental fate (D23688) and ecotoxicity (D233184) data submitted for racemic metolachlor and S-metolachlor to be comparable. For the purposes of this assessment, data for S-metolachlor are used if available. Gaps in the S-metolachlor data

set are filled with data for racemic metolachlor if they are available.

Figure 1 Chemical structure of metolachlor a nd all possible stereochemical conformations



### Empirical formula: C 15 

### H 22 

### NO 2 

### Cl Molecular weight: 283.8 CAS Registry Nos.: 51218-45-2 and 87392-12-9

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### Metolachlor is a pale yellow to light brow n liquid with a boiling poi nt of 334 degrees C; density of 1.117 g/cm 3 

### at 20 degrees C; log P
ow 

### of 3.05 at 25 degrees C; and vapor pressure of 2.8 x 10 -5 

### mm Hg at 25 degrees C. Metolach lor is completely miscible in nhexane, methanol, acetone, toluene, and n-octanol at 25 degrees C.

No impurities of toxicological concern have been identified for metolachlor or Smetolachlor.

Two degradates have been identified as pot entially of toxi cological concern. Each of these two degradates, the ethane sulfonic ac id (ESA) and the oxanilic acid (OA) of metolachlor are considered as part of this assessment. The degradation products also

have chiral centers and are stereoisomers. Structures are shown in Figure 2

.

Figure 2 Chemical structures for S-metolachlor degradates



### 2.2 Environmental Fate Summary

The environmental fate data for S-metolach lor are based on bridged environmental fate

data for S-metolachlor and racemic metolachlo r. The bridging strategy relies on the fact that the type and quantities of transforma tion products between racemic metolachlor and

S-metolachlor are similar.

The information from all acceptable environm ental fate data indicate that parent metolachlor appears to be moderately persistent to persistent in soil. It also ranges from

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### mobile to highly mobile in different soils a nd it has been detected extensively in surface water and groundwater. Metolachlor degrad ation appears to be dependent on both microbially mediated (a erobic soil metabolism t 1/2 

### = 66 days, 37.8 days, 37.8 days, 14.9 days, 13.9 days, and 50.3 days, anaerobic soil metabolism t 1/2 

### =81 days) and abiotic processes (photodegrad ation in water t 1/2 

### = 70 days under natural sunlight and photodegradation on soil t 1/2 

### = 8 days under natural sunlight).

The major degradates of metolachlor were initially identified as CGA-51202 (metolachlor OA), CGA-50720, CGA-41638, CGA-37735, and CGA-13656. Subsequent studies also identified CGA-354743 (metolachlo r ESA). Of these major degradates,

metolachlor ESA and metolachlor OA have been identified in both groundwater and surface water. Depending on the soil ( i.e., organic matter content), metolachlor has the potential to range from a moderately mobile to a hi ghly mobile compound with K d 

### values ranging from 0.11 to 44.8, and K

oc 

### values ranging from 21.6 to 367.

EFED concluded there is no significant di fference in soil sorption affinity between

metolachlor and S-metolachlor. There was no statistical difference between K

oc 

### values in non-paired batch equilibrium studies; similar K

oc 

### coefficients for metolachlor (mean

K
oc 

### =249.250) and S-metolachlor (mean K

oc 

### =265.875) were observed in paired batch equilibrium studies. These data suggest that metolachlor and S-metolachlor are both expected to be highly mobile to mob ile in soil and water environments.

Field dissipation studies indicate that metolach lor is persistent in surface soil, with half lives ranging from 7 to 292 days in the upper six inch soil layer, depending on geographic location. Metolachlor was reportedly detected as deep as the 36 to 48 inch soil layer in some studies. Metolachlor OA (CGA-51202), wa s detected (0.11 ppm) as deep as the 30-36 inch soil depth (MRID 41335701); CGA-40172 was detected as deep as the 36-48 inch depth (MRID 41309802); CGA-40919 was dete cted in the 36-48 inch depth (0.21 ppm in MRID 41309802); and CGA-50720 was not detected (LOD = 0.07 ppm) in any soil segment at any interval.

2.3 Mode of Action

S-metolachlor is a biosysnthesis inhib itor, absorbed by th e roots and shoots ( www.syngentacropprotection-us.com /prod/herbicide/dualiimagnum) . It translocates in the plant. S-metolachlor may be active in the soil for several months following application. Germinating monocots primarily ab sorb metolachlor thr ough the shoot just above the seed, and germinating diots absorb at the shoot and the roots (Zimdahl 1993).

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### A single specific biochemical target of meto lachlor and other chloroacetamide herbicides has not been defined and it appears the chemicals may act via multiple pathways. Alkylation appears to be important in phytot oxicity (Jablonkai 2003) and lipophilicity has been correlated with algal reproduction effects (Junghans et al. 2003). Covalent inhibition of coenzyme A elongation (Schmalfuss et al. 2000) and covalent inhibition of very-long-chain fatty acid synthesis via chal cone synthase have been proposed as

mechanisms of action in te rrestrial plants (Eckermann et al. 2003). Inhibition of protein biosynthesis has also been proposed as a mechanism of action in plants (Pillai et al. 1979). Several proposed mechanisms of action in plants involve irreversible, covalent binding to cysteine residues. Consistent with cysteine reactivity, glutathione Stranserfase has been shown to be important in detoxifying chloroacetanilide herbicides in tolerant plants (Rossini et al. 1998).

2.4 Use Characterization

The proposed label addition includes an appli cation rate of 1.0-1.33 pints of formulated product per acre (equivalent to 0.95-1.27 lb ai/A) for pumpkins and winter squash. Unless otherwise specified, EFED has assumed that general use dire ctions on the current label (EPA Reg. #100-818, Trade Name Dual II Magnum®) apply to both pumpkins and winter squash. The label specifies the herb icide be applied no cl oser than 400 ft to sensitive plants. This specification was incorp orated into the terres trial plant evaluation. For pumpkins and squash it is proposed for pre-emergence, post-plant use, as a groundspray. Specific use rate is dependent on soil texture and percent organic matter, with the lower rate applied to sandier, lower organic content soils. Based on communications with IR-4 personnel and the registrant, the maximum yearly application rate for these crops is 1.33 pt/A/year.

For the purpose of aquatic and terrestrial modeling EFED has inte rpreted the available application information as follows:

• Application method: ground spray

• Frequency: 1 application

• Timing: 1 June

• Maximum yearly rate: 1.33 pt/A/year (1.27 lb ai/A/year)

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### Pumpkins

Pumpkins are a minor crop, with appr oximately 67,000 acres under cultivation (AgCensus 1997). They are grown in nearly every state including Alaska and Hawaii, although the most intense cultivation is in the Northeast (New Jersey, eastern Pennsylvania, southeastern New York, Conn ecticut, and Massachusetts), Pacific Coast (California, Washington, and western Oregon), and uppe r Midwest (Michigan, Ohio, Wisconsin, Indiana, and Illinois). They ha ve a long growing period, and are generally planted in late May or earl y June, and harvested in mid-October to November.

Winter Squash

Winter squash is also a minor crop, and total acreage statistics are included in a more general “squash” group. Cultiv ation patterns are similar to pumpkins, with the most intense cultivation in the Northeast (New Je rsey, eastern Pennsylvania, southeastern New York, Connecticut, and Massachusetts) and Pa cific Coast (California, Washington, and western Oregon). Squash are also grown in the Southeastern Coasta l Plain, Florida, and

Texas. 2.5 Assessment Endpoints

Assessment endpoints are selected based on ecosystems typically at risk from agricultural pesticide applications. Specific ecological effects are evaluated based on toxicity information from guideline tests and open literature data, and focus on the general categories of survival, growth, and reproduc tion. Information regarding sub-lethal effects, if available, is discussed in the ri sk characterization. EF ED assesses behavioral or biochemical endpoints if they are quant itatively linked to effects on survival or fecundity.

2.5.1 Ecosystems Potentially at Risk

For typical crop applications, the ecosystem at risk is the field itself, in terms of organisms that might be sprayed during a pplication, organisms affected by accumulation of s-metolachlor in the soil; a nd the adjacent aquatic and terres trial environments affected due to runoff, spray drift, or groundwater contamination. In water bodies receiving runoff from agricultural fields, pelagic and benthic elements are considered. Terrestrial organisms assessed include non-ta rget plants, insect s, amphibians, reptiles, birds, and

mammals. Because s-metolachlor is an herbic ide, potential affects on non-target plants have been addressed at length. The c onceptual model for s-metolachlor ( Figure 3 ) is located on the following page.

15

### 16 2.5.2 Ecological Effects

Evaluation of ecological effects focuses ini tially on direct effects to the groups of organisms residing in the ecosystems at ris k, based on ratios (risk quotients) of the estimated environmental concentration (EEC) to a designated toxicity endpoint for a surrogate test organism. If pre-established levels of concern (LOCs) are exceeded for direct effects, indirect e ffects to endangered species ( e.g ., food chain, decrease in community diversity) are eval uated based on the group of organisms exceeding the LOC. Details on the RQ method and LOCs are in Appendix G.

Direct Direct effects evaluated are the survival, gr owth, and reproduction of various taxa of organisms potentially exposed to s-metola chlor. Taxonomic groups evaluated include aquatic plants (algae and vascul ar), aquatic invertebrates, aquatic vertebrates, terrestrial plants, terrestrial invertebrates, birds, a nd mammals. There are currently no guideline tests for reptiles or amphibians, so these taxa are evaluated using bird data as a surrogate for reptiles and terrestrial phase amphibians , and fish as a surroga te for aquatic phase amphibians. Both acute and ch ronic effects are considered.

Indirect When herbicides are applied, indirect e ffects may include a decline in primary productivity, or change in composition of plan t communities proximate to the treated area or systems (wetlands and water bodies) recei ving runoff from the site. If LOCs are exceeded for any taxa, potential indirect effects to endangered species are assessed.StressorSources-Metolachlor applied to cropFigure 3 Conceptual model for S-metolachlor effectsRunoffDirect applicationSpray driftReceptorsBirdsMammalsTerrestrialinsectsSoil accumulation,leaching and runoffIndividual organismsReduced survivalReduced growthReduced reproductionAquaticplantsinvertebratesvertebratesTerrestrialplantsSoilinvertebratesFood chainReduction in primary productivityReduction in preyShift in community compositionHabitat integrityReduced coverCommunity changeAttributeChange17

### 2.7 Risk Hypotheses

• S-Metolachlor, OA, or ESA in runoff fr om treated areas may kill aquatic plants, aquatic invertebrates, or fish.

• S-Metolachlor may be toxic to non-target plants.

• S-Metolachlor residues in plant and anim al dietary sources may affect growth, survival, or fecundity of birds and/or small mammals ingesting these materials.

2.8 Key Uncertainties and Information Gaps

• Bioavailability of S-metolachlor to non- target organisms is influenced by site

characteristics. An effort has been made to examine a variety of sites typical of areas where it might be used. Scenarios and input pa rameters have been selected to represent

conditions where S-metolachlor is most bioavailable. Over all, conditions have been selected to develop a conservative, screening level estimate. In some locations and under some conditions, risk may be overestimated.

• Natural genetic variability in wild organisms may affect their response to Smetolachlor, and the distribution of species sensitivity is not we ll understood. Risk may be under- or over-estimated for any given spec ies by available toxic ity data and use of
surrogate taxa.

• The locations of sensitive and/or valuab le plant communities are not available, thus effects on these communities can only be assessed in a general, qualitative sense.

• The enantioselectivity of toxicity and e nvironmental fate for metolachlor ESA and

metolachlor OA were not consid ered in the assessment.

• Aerobic and anaerobic aquatic metabolism half-lives for metolachlor ESA and

metolachlor OA were assumed to be st able due to the lack of data.

18

### 3. Exposure Assessment

EFED conducted the exposure assessment using standardized exposure modeling.

3.1 Label Application Rates and Intervals

The application rates, applic ation frequency, and other info rmation used in the exposure

assessment are listed in Table 3 . These conditions are based on information contained in the currently existing label as well as the language for the proposed new use.

Table 3 Label Application Rates

Application
Rate Soil Texture First Application Date Frequency Interval

0.95 lb ai/A Light, Low organic matter June 1 1 N/A

1.27 lb ai/A Moderate-heavy, Organic matter >3% June 1 1 N/A



### 3.2 Aquatic Exposure

Tier II EFED aquatic exposure modeling use the linked Pesticide Root Zone Model and Exposure Analysis Model System (PRZM- EXAMS). PRZM uses the chemical’s physical and environmental fate properties a nd the site characteri stics to predict the concentration of pesticide in runoff and en trained sediment from the field. EXAMS estimates the concentration of pesticide in an edge-of-field sm all water-body receiving runoff from the field. The water-body has no outflow with a constant volume (20 million liters), and is intended to represen t an upper-end occurren ce concentration.

A complete fate data set was not availabl e for the degradates metolachlor ESA and metolachlor OA, thus EFED opted to us e GENEEC (Tier I) to model aquatic concentrations of these compounds.

3.2.1 PRZM-EXAMS Modeling Inputs and Scenario Selection

The aquatic exposure assessment for S-meto lachlor was conducted to assess use on pumpkins and winter squash. EFED currently has no standard scenarios for these crops. Standard row crop scenarios were selected to assess runoff potential from vulnerable use sites in several of the more common growing areas

. Application rates for the various scenarios were selected based on the percent of organic matter in soil horizon 1 in the scenario. Other input parameters were se lected according to EFED Input Parameter

Guidance for PRZM/EXAMS 1



### . Input parameters are shown in Table 4

.

1 Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides. Version II, 2/28/02.



### 19Table 4 Input Parameters for PRZM-EXAMS Modeling

Parameter Value Comments Source Application Rate (kg a.i./ha) 1 -ground spray 1.064 OM<3% label Application Rate (kg a.i./ha) 1 - ground spray 1.42 OM>3% label Molecular Weight (grams/mole) 283.8 Solubility (mg/L) 4800 10X reported value Vapor Pressure (torr) 2.8E -5
Henry’s Constant (atm m 3 /mol) 3.75E -5 product chemistry

K d (L/kg) 181 Average K
oc 2 MRID00078291
MRID43928935
MRID40430203
MRID40476404
MRID43928937
MRID40495602
MRID40495603
MRID40495604 Aerobic Soil Metabolism Half-life (days) 48.9 Estimated upper 3

90 th percentile MRID41309801
MRID43928936
MRID45499606 Aerobic Aquatic Metabolism Half-lif e (days) 141 Based on 3X single aerobic aquatic
metabolism linear
first order half-life MRID41185701

Anaerobic Aquatic Metabolism Half-life (days) 234 Based on 2X single anaerobic aquatic
metabolism linear
first order half-life MRID41185701

Photodegradation in Water (days) 70 MRID40430202 Hydrolysis Half-life (days) Stable MRID40430201

1 - Application rate given in input units for PR ZM-EXAMS. Conversion is kg/ha x 1.12 = lb/A

2 - Average K
oc using values 118.5, 303.0, 151.4, 241.4, 66.8, 21.6, 110.4, 74.4, 175.0, 333.3, 230.0, 244.7, 226.3, 367.2, 176. 5, 120.7, 111.1 as per “ Guidance for Chemistry and Management Practice Input Parameters for Use in Modeling the Environmental Fate and Transport of
Pesticides” dated February 28, 2002.

3 - Upper 90 th Percentile based on acceptable aerobic me tabolism half-lives of 66, 37.8, 37.8, 14.9, 13.9, and 50.3 days.



### 3.2.2 PRZM-EXAMS Modeling Output

The 1-in-10-year peak concen trations of S-metolachlor ranged from 9.65 ppb (PA corn) to 35.11 ppb (CA lettuce). Water concentratio ns did not necessar ily correlate with application rate, as the highe r aquatic concentrations occu rred in the low soil organic matter, lower application rate scenarios. Th e 1-in-10-year 60-day concentrations of Smetolachlor ranged from 6.22 ppb (FL peppers) to 29.07 ppb (CA lettuce).

20Table 5 PRZM-EXAMS EECs

Peak 4 days 21 days 60 days Crop Scenario Application
Method μ g/L (ppb) Application Rate 1.064 kg/ha (OM <3.0%)
CA lettuce Ground 35.11 34.81 33.31 29.07 FL peppers Ground 24.32 21.65 14.04 6.22 Application Rate 1.42 kg/ha (OM >3.0%)

IL corn Ground 9.87 9.77 9.41 5.33

PA corn Ground 9.65 9.56 9.20 8.15



### 3.2.3 GENEEC Modeling for Degradates

Limited data were available for modeli ng the degradates metolachlor ESA and

metolachlor OA. These data included the so il adsorption/desorption studies for both ESA (MRID 44931722) and OA (MRID 40494605), as well as the conversion efficiency of metolachlor to the two degradates (MRIDs 43928936, 41309801). Application rates for the two degradates were determined by multiplying the maximum S-metolachlor application rate (1.27 lb ai/A) by the fraction of the relevant de gradate. Half-lives for the two compounds were estimated using the de cline portion of the formation and decline data contained in the Comparative Ae robic Soil Metabolism Study (MRID 43928936). For other parameters where data was not av ailable, the compounds were conservatively assumed to be stable. GENEEC input parameters are shown below ( Table 6 ). A 400-ft

buffer was assumed.

Table 6 GENEEC Input Parameters for Degradates

Parameter Value Comments Source Application Rate ESA (lb a.i./ha) 0.15 1.27 lb ai/A X 0.12 MRID43928936 Application Rate OA (lb a.i./ha 0.36 1.27 lb ai/A X 0.28 MRID41309801

K d ESA (L/kg) 0.041 MRID44931722

K d OA (L/kg) 0.079 Lowest non-sandy soil, Maryland clay MRID40494605 Solubility (mg/L) 4800 10X reported value product chemistry
Aerobic Soil Metabolism Half-lif e ESA (days) 162.5 MRID4392836 Aerobic Soil Metabolism Half-life OA (days) 127.5 Based on decline portion of formation
and decline data Aerobic Aquatic Metabolism Half-life (days) 0 Anaerobic Aquatic Metabolism Half-life(days) 0 Photodegradation in Water (days) 0 MRID40430202 Hydrolysis Half-life (days) 0 Assumed stable

MRID40430201



### 21

### EECs for the degradates were 8.25 ppb for metolachlor ESA and 19.63-19.65 ppb for

metolachlor OA.

Table 7 EECs for Degradates

Peak 4 days 21 days 60 days Degradate Application
Method μ g/L (ppb)
Metolachlor ESA Ground 8.25 8.25 8.25 8.25
Metolachlor OA Ground 19.65 19.65 19.65 19.63



### 3.3 National Surface Water Monitoring Data Assessment

In the 2002 TRED for S-metolachlor, EFED evaluated data from several sources of monitoring studies (including se veral sources with treated dr inking water with detections

of metolachlor/S-metolachlor 1 

### ) for use in acute and chronic exposure estimates. Extensive monitoring data exists for metolach lor/S-metolachlor, allo wing distributions of concentrations to be estimated. Acute expos ure estimates presente d in this assessment

are the maximum measured from the distri butions of annual maximum concentrations. Chronic exposure estimates are the maxi mum measured concentrations from the distribution of time weighted annua l mean concentrations.

At the national scale, the frequency of det ection of metolachlor/S-metolachlor from the entirety of the monitoring data eval uated (NAWQA, ARP, STORET, and USGS Reservoir studies) suggests that metolachlo r/S-metolachlor contamination in both surface water and groundwater is widespread. In addi tion, the data suggest that the two primary degradates (metolachlor ESA and metolach lor OA), are detected in surface and groundwater resources in Iowa and Illinois at frequencies (99% for ESA and 92% for OA) and at concentrations exceeding the pa rent compound. It is likely that where

metolachlor/S-metolachlor is detected in surface and groundwater the degradates are present as well, although many monitoring studies do not measure them.

From the available national-scale data, the highest annual maximum concentration of

metolachlor/S-metolachlor in surface water is 77.6 μ 

### g/l (NAWQA surface water monitoring data). The maximum value de tected from all data evaluated was 138.8 μ 

### g/l (STORET data). From the available data, the maximum time-weighted mean

concentration of metolachlor/S-me tolachlor in surface water is 4.3 μ 

### g/l from the NAWQA surface water monitoring data. These concentrations were primarily detected in the Midwestern corn belt, a high use area

From the available national-scale data, the maximum peak concentration of metolachlor

ESA is 12.40 μ 

### g/l and the maximum time-weighted mean concentration of metolachlor

ESA is 7.30 μ 

### g/l (Iowa NAWQA surface water monitoring data). The maximum peak

concentration of me tolachlor OA is 6.75 μ 

### g/l and the maximum time-weighted mean

concentration of me tolachlor OA is 2.27 μ 

### g/l from the Iowa NAWQA surface water

1 These studies do not discriminate between racemic metolachlor and S-metolachlor.



### 22

### monitoring data. More details on the resu lts of the evaluation of surface water monitoring data may be found in the TRED drinking water assessment dated May 22,

2002.

3.5 Bird and Mammal Exposure (TREX)

EFED estimates exposure of birds and mamm als using the Terrestrial Exposure Model (TREX). TREX uses the Kenaga no magram, as modified by Fletcher et al. (1994) to determine pesticide residues on several catego ries of food items, then calculates the potential dose an organism might receive from ingesting contaminated items using allometric equations. Dose estimates in Table 8 and Table 9 are based on the upper bound dose and the assumptions that the organi sm exclusively eats one type of food item and forages only in the treated and/or overspr ay areas. S-metolachlor translocates in plant tissue and the residence time of the parent compound or any degradates is unknown. For pumpkins and winter squash, only a single application is propose d, thus residues in the plant are not expected to exceed residues on the plant.

At the lower application rate (0.95 lb a i/A) avian doses ranged from 4.1 to 260 mg/kgbw/day. Doses ranged from 5.5 to 347 mg/kg-bw/d ay at the higher app lication rate (1.27 lb ai/A).

Table 8 Bird Dose Estimates

Dose-based EECs (mg/kg-bw) Feeding Category Dietary-basedEECs (mg/kgfood item) Small (20 g) Medium (100 g) Large (1000 g) Application Rate 0.95 lb ai/A Short grass 228.00 259.67 148.07 66.29 Tall grass 104.50 119.02 67.87 30.39 Broadleaf plants/small insects 128.25 146.06 83.29 37.29 Fruits/pods/seeds/large insects 14.25 16.23 9.25 4.14 Application Rate 1.27 lb ai/A Short grass 304.80 347.14 197.95 88.63 Tall grass 139.70 159.10 90.73 40.62 Broadleaf plants/small insects 171.45 195.26 111.35 49.85 Fruits/pods/seeds/large insects 19.05 21.70 12.37 5.54



### 23

### At the lower application rate (0.95 lb a i/A) mammal doses ranged from 0.48 to 217 mg/kg bwt/day. Doses ranged from 0.65 to 291 mg/kg bwt/day at the higher application rate (1.27 lb ai/A).

Table 9 Mammal Dose Estimates

Dose-based EECs (mg/kg-bw) Feeding Category Dietary-basedEECs (mg/kgfood item) Small (15 g) Medium (35 g) Large (1000 g) Application Rate 0.95 lb ai/A

Herbivores and Insectivores Short grass 228.00 217.38 150.24 34.83 Tall grass 104.50 99.63 68.86 15.97 Broadleaf plants/small insects 128.25 122.28 84.51 19.59 Fruits/pods/seeds/large insects 14.25 13.59 9.39 2.18
Granivores Fruits/pods/seeds/large insects 14.25 3.02 2.09 0.48 Application Rate 1.27 lb ai/A

Herbivores and Insectivores Short grass 304.80 290.60 200.85 46.57 Tall grass 139.70 133.19 92.05 21.34 Broadleaf plants/small insects 171.45 163.46 112.98 26.19 Fruits/pods/seeds/large insects 19.05 18.16 12.55 2.91
Granivores Fruits/pods/seeds/large insects 19.05 4.04 2.79 0.65



### 3.6 Terrestrial Plant Exposure (TerrPlant & AgDrift)

Currently, EFED uses the TerrPlant Mode l (Version 1.2.1) to evaluate exposure of terrestrial plants to pesticides applied on agri cultural fields. In cases where spray drift may be of concern in the risk assessment EFED also uses the AgDrift model.

3.6.1 TerrPlant

TerrPlant has two basic exposure scenarios. Th e first is an adjacent upland area, which is exposed to the pesticide via drift and dissolv ed concentrations in sheet runoff. The second is an adjacent semi-aquatic (wetland) ar ea, which is exposed to the pesticide via

drift and to dissolved concentrations in cha nnelized runoff. Drift is calculated as a percentage of the application rate (1% for ground, and 5% fo r aerial, airblast, or spray chemigation) and is not adjusted for distan ce from the application site. The amount of dissolved pesticide in the runoff component is estimated based on solubility of the active ingredient. TerrPlant estimates are shown in Table 10 . Total loading (runoff plus drift) for S-metolachlor ranged from 0.08-0.65 lb ai /A, depending on application rate, and environment. Drift estimates were approxima tely 0.01 lb ai/A. TerrPlant was also used to calculate EECs for the two major degradat es, ESA and OA. App lication rates for the degradates were estimated by multiplying the highest application rate of the parent by the highest single day conversion efficiency to the degradate, based on the aerobic soil

24

### metabolism study (12% for ESA, 28% for OA) . Total loading ranged from 0.01-0.08 lbs ai/A for ESA, and from 0.02-0.19 lbs ai/A for OA.

Table 10 Terrestrial Plant Exposure (TerrPlant)

Total Loading (Runoff +Drift) (lb ai/A) Drift EEC (lb ai/A) Application Rate Upland areas Wetland areas All areas
0.95 lb ai/A 0.0570 0.4845 0.0095
1.27 lb ai/A 0.0762 0.6477 0.0127 Degradate ESA 0.15 lb ai/A 0.0090 0.0765 0.0015 Degradate OA 0.36 lb ai/A 0.0216 0.1836 0.0036



### 3.6.2 AgDrift

Because of concerns about effects on non-target plants located in overspray or spray drift areas, EFED elected to perform an analysis of potential deposition of s-metolachlor using AgDrift modeling software. AgDrift was deve loped using extensive field-measured data sets, and provides a method of estimating deposition of the compound of concern at a specified distance away from the application source. Deposition is heavily dependent on the method of application and droplet size. A Tier I analysis, which is driven primarily by these two variables, was conducted for bot h ground and aerial applications. AgDrift was run in the Tier I, Terrestrial Assessm ent, Point Deposition mode. Droplet size evaluated was ASAE very fine-fine, and values shown represent the 90 th 

### percentile estimate. Deposition was estimated fo r ground application, with a low boom ( Table 11 ). For this set of application c onditions, the 1% drift assumed in TerrPlant is equivalent to approximately 100 ft away from the application site

. EFED notes label directions specify that S-metolachlor not be sprayed clos er than 400 ft to sensitive plants.

Table 11 Terrestrial Plant Exposure (AgDrift, Ground spray)

Point Deposition (lb ai/A) Distance from Application Source (ft) Fraction
of Applied Proposed Rate (1.27 lb ai/A) Proposed Rate (0.95 lb ai/A)

10 0.0923 0.1172 0.0877

20 0.0437 0.0555 0.0415

30 0.0291 0.0370 0.0276

40 0.0218 0.0277 0.0207

50 0.0177 0.0225 0.0168

60 0.0149 0.0189 0.0142

70 0.0130 0.0165 0.0124

80 0.0115 0.0146 0.0109

90 0.0104 0.0132 0.0099

100 0.0095 0.0121 0.0090

150 0.0066 0.0084 0.0063

200 0.0051 0.0065 0.0048

250 0.0042 0.0053 0.0040

300 0.0035 0.0044 0.0033

350 0.0030 0.0038 0.0029

500 0.0021 0.0027 0.0020

550 0.0019 0.0024 0.0018

600 0.0017 0.0022 0.0016



### 25

### 4. Effects Assessment

Toxicity endpoints are esta blished based on data gene rated from guideline studies submitted by the registrant, and from open literature studies that meet the criteria for

inclusion into the ECOTOX database maintain ed by EPA/ORD. EFED policy is to use the effects endpoint from the most sensitive tested species for each taxa evaluated. In aquatic systems, taxa evaluated include aquatic plants, invertebrates, and fish. Fish serve as a surrogate for aquatic-phase amphibians. Where data are available, separate endpoints are used for freshwater and estuarine/marine organism s. In terrestrial systems,

taxa evaluated include birds and mammals. Bird endpoints are ge nerally derived from guideline studies on bobwhite quail and/or mallard duck. Bird data are used as a surrogate for reptiles and terrestrial-phase amphibians. Mammal data are derived from guideline studies conducted on labo ratory rats, mice, or rabbits.

4.1 Aquatic Hazard Summary

S-metolachlor is classified as slightly to moderately toxic to both fish and aquatic invertebrates, based on both registrant-submitted guideline studies ( Table 12

- Table 14 ) and data from the open literature ( Table 15 ). Acute LC 50 

### s for fish range from 3.2 mg/L (bluegill sunfish, MRID 43928910) to 8.4 mg/L (fathead minnow, ECOTOX 6797). Data available for an estuarine fish (sheepsh ead minnow, MRID 43487101, racemic) indicate toxicity to fish in a brackish water environment is similar to freshwater. Acute LC 50 

### s for invertebrates range from 3.8 mg/L (midge fl y, ECOTOX 6797) to 26 mg/L (water flea, MRID 43928912). Values used to calculate RQ s (3.2 mg/L for fish, 3.8 mg/L for aquatic invertebrates) are marked in the tables with an asterix (*). ECOTOX data included results for two amphibian species, the African clawed frog (LC 50 

### 13.6 mg/L) and the American bullfrog (LC 50 

### 17.4 mg/L). Based on this limited data set, it appears amphibian sensitivity to metolachlor and S-me tolachlor is similar to that of aquatic

invertebrates and fish. How sensitive these species are relative to other amphibians is unknown, thus EFED elected to use the more sensitive fish endpoint to assess potential effects on amphibians.

Effects on aquatic plants occur at lower con centrations than for aquatic animals. LC 50 

### s range from 0.008 mg/L (green alga, MRID 43928929) to >3.00 mg/L (water milfoil, ECOTOX 19461). Based on the available data, green algae and some vascular plants appear to be most sensitive to the effects of metolachlor and S-metolachlor. Diatoms seem to be less sensitive, and blue-green alga e, along with some other species of vascular plants are the least sensitive of the aquatic plants.

Data for the two major degradates of metolach lor, ESA and OA were available. Of the two, OA was most toxic to the aquatic invertebrate tested (water flea, LC 50 

### 15.4 mg/L). OA effects on aquatic invertebrates occur in approximately the same concentration range as the parent compound. Other than this inst ance, both degradates are generally less toxic to all organisms than the parent. LC 50 

### s for the other organisms tested (green algae, vascular plants, fish) were all >50 mg/L. Th e degradate ESA was most toxic to vascular plants (LC 50 

### 43 mg/L) and fish (LC 50 

### 43 mg/L). For both green algae and aquatic

26

### invertebrates, the LC 50 

### was greater than 99 mg/L. No open literature data was available for the degradates.

Sublethal effects were noted in some of the gui deline tests, usually in test concentrations in which mortality occurred. Effects noted in fish tests included lethargy, distended abdomen, swimming at the surface, and loss of equilibrium. Sublethal effects noted in invertebrate tests include lethargy (oyster, mysid, water flea), redu ced feeding (oyster), and dark pigmentation (water flea).

Chronic effects (reduced growth) in fish were noted at concentrations of 0.056 mg/L (fathead minnow, MRID 44995903) to 2.2 mg/L (sheepshead minnow, MRID 43044602). Effects in aquatic invertebrates were similar, but occurred at slightly higher concentrations, ranging from 4.0 mg/L (mys id MRID 43487103) to 9.4 mg/L (water flea MRID 46322101).

Two studies in the open literatu re reported behavioral and/or biochemical endpoints. One study (ECOTOX 20274) reported cellular damage in American bullfrog tadpoles at 0.27 mg/L. Another study, performed on the ru sty crayfish (ECOTOX 68515), showed a reduced response to predator and food source olfactory cues at metolachlor concentrations of 0.025 mg/L.

27Table 12 Acute Aquatic Data from Registrant-submitted Studies

Species LC 50 (mg/L) 95% C.I. (mg/L) NOAEC (mg/L) Classification (MRID) Freshwater Organisms Green alga (Selenastrum capricornutum) 0.008 * 0.0026-0.025 0.0015 Core (43928929)
S-metolachlor

Duckweed (Lemna gibba) 0.021 * 0.019-0.023 0.0076* Core (43928931)
S-metolachlor

Water flea (Daphnia magna) 26* slightly toxic 23-30 4.8 Core (43928912)
S-metolachlor Bluegill Sunfish (Lepomis macrochirus) 3.2 * moderately
toxic 2.8-4.6 1.5 Core (43928910)
S-metolachlor Estuarine/Marine organisms

Marine diatom (Skeletonema costatum) 0.11 * 0.091-0.128 0.021 Core (43928930)
S-metolachlor

Mysid shrimp (Mysidopsis bahia) 4.9 moderately
toxic 4.2-5.9 2.3 Core (4387103)
Racemic Eastern oyster (Crassostrea virginica) 1.6 * moderately
toxic 1.4-1.9 0.7 Core (43487102)
Racemic Sheepshead minnow (Cyprinodon varigetus) 9.8 * moderately
toxic 8.5-11.4 3.6 Core (43487101)
Racemic

* denotes values used to calculate RQs

Table 13 Chronic Aquatic Data from Registrant-submitted Studies

Species NOAEC (mg/L) LOAEC (mg/L) Endpoints Affected Classification (MRID) Freshwater Organisms

Water flea (Daphnia magna) 4.9 * 9.4 Length Core (46322101)
Racemic

Fathead minnow (Pimephales promelas) 0.030 * 0.056 Dry weight Core (44995903)
S-metolachlor Estuarine/Marine organisms

Mysid shrimp (Mysidopsis bahia) 2.3 * 4.0 Lethargy, dark pigmentation Core (43487103)
Racemic

Sheepshead minnow (Cyprinodon varigetus) 1.0 * 2.2 Length Supplemental (43044602)
Racemic

* denotes values used to calculate RQs



### 28Table 14 Acute Aquatic Degradate Data from Registrant-submitted Studies

Species LC 50 /EC 50 (mg/L) 95% C.I. (mg/L) NOAEC (mg/L) Classification (MRID) Degradate-ESA (CGA-354743) Green algae (Selenastrum capricornutum) >99.5 ND 99.5 Supplemental (44931720)

Duckweed (Lemna gibba) 43 * 30-61 4 Core (44931720)

Water flea (Daphnia magna) >108 * practically
nontoxic ND 108 Core (44931703)

Rainbow Trout (Onchorynchus mykiss) 43 * slightly toxic 36-64 36 Supplemental (44931702)

Degradate-OA (CGA-51202) Green algae (Scenedesmus subspicatus) 57.1 * 29.3-infinity 29.3 Supplemental (44929515)

Duckweed (Lemna gibba) >95.4 ND 95.4 Core (4492514)

Water flea (Daphnia magna) 15.4 * slightly toxic 13.0-18.4 5.2 Supplemental (44929503)

Rainbow Trout (Onchorynchus mykiss) >96.3 * slightly toxic ND >96.3 Supplemental (44929501)

ND – Not determined, * denotes values used to calculate RQs



### 29Table 15 Aquatic Data from ECOTOX

Species LC 50 /EC 50 (mg/L) LOAEC (mg/L) NOAEC (mg/L) Endpoints
Measured (Lifestage) ECOTOX
Reference #

Freshwater plants–Survival, reproduction, and growth endpoints Green algae (Selenastrum capricornutum) 0.04 NG NG Population (N/A) 19186

Green algae (Chlamydomonas reinhardtii) 1.14 NG NG Population (N/A) 19461

Bluegreen algae (Anabeana flos-aquae) 3.00 NG NG Population (N/A) 19186

Vascular – Coontail (Ceratophyllum demersum) 0.07 NG NG Biomass (N/A) 19461

Vascular - Water milfoil (Myriophyllum heterophyllum) >3.00 NG NG Biomass (N/A) 19461

Freshwater animals –Survival, reproduction, and growth endpoints

Fathead minnow (Pimephales promelas) 8 to 8.4 NG NG Mortality (adult) 6797 (technical) African clawed frog (Xenopus laevis) 13.6 NG NG Mortality (embryo) 66376 (technical) American Bullfrog (Rana catebeiana) 17.4 NG NG Mortality (tadpoles) 20274 (formulation)

Water flea ( Daphnia magna) 4.3* NG NG Mortality (Neonates) 67700 (unknown)

Water flea (Daphnia magna) 23.5 NG NG Mortality (not stated) 6797 (technical)

Water flea (Daphnia magna) 26.0 NG NG Mortality (not stated) 6797 (Emulsifiable concentrate) Midge fly (Chironomus plumulosus) 3.8 * NG NG Mortality (not stated) 6797 (technical)

Midge fly (Chironomus plumulosus) 4.4 NG NG Mortality (not stated) 6797 (Emulsifiable concentrate) Hydra (Hydra attenuata) >45 NG NG Mortality (not stated) 67700 (technical) Freshwater organisms – Behavioral and biochemical endpoints American Bullfrog (Rana catebeiana) ND 0.27 NG Cellular damage (tadpoles) 20274 (formulation) Rusty crayfish (Oronectes rusticus) NG 0.025 <0.025 Behavioral
modifications 68515 (technical) NG-not given in reference

* Used in RQ calculation for aquatic invertebrates



### 30

### 4.2 Terrestrial Plant Hazard Summary

Vegetative vigor and seedling emergence guideli ne tests were available for S-metolachlor ( Table 16 ). Both monocots and dicots were mo re sensitive in the seedling emergence tests, which was not unexpected given S-me tolachlor’s mode of action. The seedling emergenceEC 25 

### for the most sensitive monocot (ryegrass) was 0.0048 lb ai/A, and the

EC 25 

### for the most sensitive dicot (lettuce) wa s 0.0057 lb ai/A. In terms of vegetative vigor, monocots appeared significantly more sensitive than dicots, with a monocot (ryegrass) EC 25 

### of 0.021 lb ai/A, and dicot (cucumber) EC 25 

### of 0.27 lb ai/A. The seedling emergence NOAEC for the most sensitive mono cot (ryegrass) was 0.001 lb ai/A, and the NOAEC for the most sensitive dicot (lettuce) was 0.0003 lb ai/A. Vegetative vigor NOAEC endpoints for monocots (ryegrass, 0.011 lb ai/A) and dicots (cucmber, 0.01 lb ai/A) were essentially the same.

Three plant studies evaluati ng effects of metolachlor and S-metolachlor on non-crop plant species were available in ECOTOX. Generally, these studies were conducted on mature and/or growing plants, rather than pr e-emergence, thus they are more comparable to the vegetative vigor endpoints than the seedling emergence endpoints from the guideline studies. Open literature studies on crop species produced less sensitive endpoints than the registrant-submitted studies. Ecological effects da ta is located in Appendix D. Table 17 shows select ECOTOX data for non-crop species. Plants have been grouped into two classes: herbaceous (grasses and forbs) and woody (trees and shrubs). This classification is intended to reflect both a difference in ecological function, and expected differences in sensitivity to th e herbicide. In orde r to establish upper and lower bounds, the most sensitive and the le ast sensitive endpoints for each group are included in the table. For the grasses and fo rbs, a test concentration of 0.11 lb ai/A was applied (ECOTOX 73233). At this concentratio n, results ranged from no observed effect (broomcorn) to a 90% reduction in height (barnyard grass). The most sensitive species

tested in the trees and shr ubs class was the Tatarian ma ple, which exhibited reduced growth at an application of 3.0 lb ai/A (ECOTOX 73251). The least sensitive species tested was the European white birch, which had no observable effect s at an application

rate of 9.1 lb ai/A.

In a natural landscape, plants most at risk from use of S-metolachlor would be newly emerging plants located near the use site Th e effect of the herbic ide on plants some of which reproduce from cut stumps and/or ro ot propagation is unknown, as no data were located evaluating these situations. Drift or runoff of S-metolachlor into primarily herbaceous natural areas near the use site (g rasslands, marshes) when mature plants are present may create a selection pressure for dicots.

Vegetative vigor and seedling mergence guidelin e tests were also available for both the ESA degradate and the OA degradates. Both are less toxic than th e parent compound. The Tier I studies submitted (MRIDs 44931718, 44929513) evaluated the effects of the degradates at an application rate of 0.5 lb ai/A. With the exception of the monocot seedling emergence endpoint for ESA, the EC 25 

### s for all endpoints were greater than the

31

### amount applied. No definitive endpoint was established for monocot seedling emergence and ESA, as the NOAEC was below the concentration tested.

Table 16 Terrestrial Plant Guideline Data

Species Common

name Class EC 25 (lb ai/A) NOAEC (lb ai/A)) Classification (MRID) Vegetative Vigor (S-metolachlor) Lolium perenne Ryegrass M 0.021 0.011
Cucumis sativus Cucumber D 0.27 0.01 Supplemental (43928933) Seedling emergence (S-metolachlor) Lolium perenne Ryegrass M 0.0048 0.001

Lactuca sativa Lettuce D 0.0057 0.0003 Supplemental (43928932) Vegetative Vigor (Degradate ESA) Lolium perenne Ryegrass M >0.5 0.5 Lycopersicon
esculentum Tomato D >0.5 0.5 Core (44931718)

Seedling emergence (Degradate ESA) Lolium perenne Ryegrass M <0.5 <0.5 Lycopersicon
esculentum Tomato D >0.5 <0.5 Core (44931718)

Vegetative Vigor (Degradate OA) Allium cepa Onion M >0.5 <0.5 Lycopersicon
esculentum Tomato D >0.5 <0.5 Core (44929513)

Seedling emergence (Degradate OA)

All monocots tested M >0.5 <0.5

All dicots tested D >0.5 <0.5 Core (44929513)

Table 17 Terrestrial Plant Data from ECOTOX

Species EC
xx (lb ai/A) LOAEC (lb ai/A) NOAEC (lb ai/A) Endpoints
Measured ECOTOX
Reference #
Grasses and Forbs Barnyard grass (Echnochloa crus-galli) 0.11 NG NG 90% reduction in height 73233

Millet (Panicum millaceum) 0.11 NG NG 50% reduction in height 73233

Broomcorn (Sorghum bicolor) NG NG 0.11 0% reduction in height 73233

Trees and Shrubs Tatarian maple (Acer tatarium) NG 3.0 NG Growth (over 2 growing seasons) 73251

Pin oak Quercus palustris NG 8.0 4.0 Growth and mortality (549 day) 73249

NG – Not given in reference



### 32

### 4.3 Avian and Small Mammal Guideline Data

Registrant-submitted data was avai lable for both birds and mammals ( Table 18 and Table

19 ). No treatment-related mortality was reporte d in any of the bird studies. On an acute effects basis, S-metolachlor is prac tically non-toxic to birds (MRIDs 43928907, 43928906). No data for S-metolachlor were available for mammals, but testing of racemic metolachlor on rats (MRID 00015523) cl assifies it as practically non-toxic. Treatment-related mortality occurred in rats at all doses tested 1670-4640 mg/kg).

Table 18 Avian and Small Mammal Guideline Data from Acute Studies

Species LD 50 / LC 50 (mg/kg-bw) 95% C.I. (mg/L) NOAEC (mg/kg-bw) Classification (MRID)

Acute dose

Bobwhite quail >2510 practically
nontoxic ND 1000 Core (43928907)
S-metolachlor

Mallard >2510 practically
nontoxic ND 2510 Core (43928906)
S-metolachlor

Rat 2780 practically
nontoxic 2180-3545 <1670 Acceptable (00015523)
Racemic Acute dietary

Bobwhite quail >4912 slightly toxic ND 2762 Core (43928908)
S-metolachlor

Mallard duck >4912 slightly toxic ND 1556 Core (43928909)
S-metolachlor

ND-no data



### Registrant submitted studies indicate meto lachlor has chronic reproductive effects on birds (MRID 46508901) and mammals (MRID 0 00808097) at the highest tested dose. These effects, noted for both groups of or ganisms at approxim ately 1000 mg/kg diet, include a reduction in egg qua lity (birds) and reduced we ight of pups (rats). No treatment-related mortality or other effects were noted in the studies.

Table 19 Avian and Small Mammal Guideline Data from Chronic Studies

Species NOAEC(mg/kgdiet) LOAEC(mg/kgdiet) Endpoint Affected Classification (MRID)

Bobwhite quail 403* 1010 Egg quality (Eggs cracked, percentage of eggs laid) Acceptable (46508901)
Racemic

Bobwhite quail 1000 >1000 No effects noted Core (44995901)
S-metolachlor

Rat 300* 1000 Reduced pup weights in F 1 and F 2 litters Acceptable (000808097)
Racemic



### 33

### 4.4 Terrestrial Insect Data

The only guideline insect tests are for honeyb ees. Registrant submitted studies include acute contact and acute oral toxicity st udies for s-metolachlor (MRID 44718402, Core).

The acute contact LD 50 

### is >200 μ g a.i./bee and the oral LD 50 

### is >85 μ g a.i./bee.

NOAELS are 200 μ g a.i./bee for acute contact and 85 μ g a.i./bee for oral dose.

4.5 Terrestrial Animal Data from ECOTOX

No data regarding S-metolachlor or meto lachlor effects on terrestrial animals are currently available in ECOTOX.

4.7 Incident Database Review

The incident database contains a total of 117 reported incidents for S-metolachlor. Of these, only two reports are for organisms other than plants. In one case, there is a report of three birds dying as a result of S-metolachlor use. The certainty of this incident was unrated, and legality designate d as unknown. The second case wa s a reported fish kill, of an unspecified magnitude. The legality of the use was design ated unknown, and the incident was designated unlikely to be the resu lt of the pesticide. The remainder of the incidents was damage to agricultural crops. Ba sed on the data, it appears that most of the reports are for the crop at the treatment site applied in accordance with registered use. The most commonly reported crops damage d were corn, cotton, and soybean. The certainty was generally rated as possible.

Incidents are reported separately for metolach lor, but the number and type of reports are similar. A total of 171 reports are in the database. Of the reports, 150 are of plant damage, again to agricultural crops under re gistered use conditions. The most commonly reported crop damage was to corn, peanuts, and soybeans. There was one reported bird kill that was rated as unlikely to be associat ed with the metolachlor use. There are 19 reported incidents of effects on aquatic animals, primarily fish. Generally, these occurred under registered use conditions, and were rated as possibly or unlikely to be associated with the application of metolachlor. One inci dent, a fish kill in Minnesota, has a certainty rating of highly probable, but was also listed as accidental misuse.

5. Risk Estimation

Risk is estimated by calculating the ratio of the expected environmental concentration and the appropriate toxicity endpo int. This value is the risk quotient (RQ), which is then compared to pre-established levels of c oncern (LOC) for each category evaluated. The RQ methodology, LOCs , and specific details of calculation are contained in Appendix G. The highest EECs and most sensitive endpo ints are used to determine the screening level RQ. Using these two values theoretically results in a conservative estimate of risk.

34

### 5.1 Aquatic RQ Summary

A summary of RQs for the parent S-metolachlor ( Table 20 ) and the degradates ESA and OA ( Table 21 ) is presented below. No LOCs fo r any of the aquatic animals were

exceeded in either freshwater or saltwater. Acute RQs for animals ranged from <0.01 to 0.02. Chronic RQs for the animals ranged from <0.01 to 0.97. For all scenarios, both the acute and endangered species LOCs were exceed ed for freshwater algae. For two uses (FL peppers and IL corn) the endangered spec ies acute risk was exceeded for saltwater algae. Endangered species LOCs were exce eded for vascular aquatic plants (RQ 1.27- 4.62) in all scenarios, and non-endangered LOCs for vascular aquatic plants (RQ 1.67- 11.58) were exceeded in scenarios with low or ganic content in the soil (CA lettuce and FL peppers). RQs for the scenarios with higher organic content (>3%) approached but did not exceed the non-endangered plant LOC.

Table 20 Summary of Aquatic RQs for S-metolachlor

Taxa Acute RQ Chronic RQ Endangered Species RQ 1

Use on CA lettuce FW Algae 4.39 a 23.41 b

FW Vascular Plants 1.67 a 4.62 b
FW Aquatic Invertebrates <0.01 0.01

FW Fish 0.01 0.97 SW Algae 0.32 1.67 b
SW Aquatic Invertebrates 0.02 0.01
SW Fish <0.01 0.03 Use on FL peppers FW Algae 3.04 a 16.21 b

FW Vascular Plants 1.16 a 3.20 b
FW Aquatic Invertebrates <0.01 <0.01

FW Fish <0.01 0.21 SW Algae 0.22 1.16 b
SW Aquatic Invertebrates 0.02 0.01
SW Fish <0.01 0.01

Use on IL corn FW Algae 1.23 a 6.58 b

FW Vascular Plants 0.47 1.30 b
FW Aquatic Invertebrates <0.01 <0.01

FW Fish <0.01 0.18 SW Algae 0.09 0.47 SW Aquatic Invertebrates <0.01 <0.01
SW Fish <0.01 0.01

Use on PA corn FW Algae 1.21 a 6.43 b

FW Vascular Plants 0.46 1.27 b
FW Aquatic Invertebrates <0.01 <0.01

FW Fish <0.01 0.27 SW Aquatic Plants 0.09 0.46 SW Aquatic Invertebrates <0.01 <0.01
SW Fish <0.01 <0.01

1 for plants, calculated based on NOAEC

a equals or exceeds aquatic plant acute risk LOC (1)

b equals or exceeds endangered species plant acute risk LOC (1)



### 35

### RQs were calculated for S-metolchlor degr adates ESA and OA, based on the exposure concentrations estimated using GENEEC. No LOCs were exceeded, and all RQs were

<0.01.

Table 21 Summary of Aquatic RQs for Degradates

Taxa Acute RQ Endangered Species RQ Degradate-ESA Application Rate 0.15 FW Algae <0.01 <0.01

FW Vascular Plants <0.01 <0.01 FW Aquatic Invertebrates <0.01

FW Fish <0.01 Degradate-OA Application Rate 0.36 FW Algae <0.01 <0.01

FW Vascular Plants <0.01 <0.01 FW Aquatic Invertebrates <0.01

FW Fish <0.01



### 5.2 Terrestrial RQ Summary

Risk quotients for terrestrial plants were ca lculated using the most sensitive plant and most sensitive endpoint. Because of the concern for herbicide impacts on non-target plants RQs were calculated using both EF ED’s standard method, TerrPlant, and also based on an AgDrift estima te of point deposition.

Terrestrial RQs for birds and mammals were calculated using EF ED’s TREX program,

version 1.1. TREX uses the Ke naga nomagram, as modified by Fletcher et al. (1994) to estimate potential chemical residue on food items, calculates exposure by estimating food consumption via allometric equations (assu ming the organism exclusively consumes contaminated items), and then calculates RQs based on a weight-adjusted LC 50



### .

5.2.1 Terrestrial Plants

Risk quotients were calculated based on th e exposures estimated by both TerrPlant and AgDrift. Calculations were made using data from both types of guideline studies (vegetative vigor and seedling emergence). Evaluations were done for both monocots

and dicots

5.2.1.1 TerrPlant

Based on TerrPlant calculations for total load ing (runoff plus drift), acute risk LOCs and endangered species LOCs are exceeded for bot h monocots and dicots in both uplands and wetlands for all application rates and methods ( Table 22 ). Acute risk total loading RQs ranged from 10 to 101 for the 0.95 lb ai/A a pplication rate, and from 13 to 135 for the 1.27 lb ai/a application rate. Based on spray drift alone, no acute risk RQs were

36

### exceeded. Acute endangered species RQs based on drift exceeded the LOC both

monocots and dicots at the 1.27 lb ai/A application rate.

TerrPlant was also used to calculate acute risk RQs for the degradates ESA and OA, using the expected conversion efficiency to es timate application rates. Because only one application rate was tested for the degradates, and the NOAECs were not determined, only the acute risk RQs were evaluated. No LOCs were exceeded. Acute risk RQs for ESA ranged from <0.01-0.17. Acute risk RQs for ESA ranged from 0.01-0.40. RQs for ESA are higher than the calculated value, be cause the test only established that the

NOAEC for ESA was >0.5 lb ai/A.

Table 22 Terrestrial Plant Risk Quotients Based on TerrPlant

Total Loading RQ (Seedling emergence) Total Loading RQ (Seedling Emergence) Drift RQ (Vegetative vigor) Upland areas Wetland areas All areas Application Rate

Monocot Dicot Monocot Dicot Monocot Dicot

Acute risk
Use at 0.95 lb ai/A 11.88 a 10.00 a 100.9 a 85.00 a 0.45 0.04
Use at 1.27 lb ai/A 15.88 a 13.37 a 134.94 a 113.63 a 0.60 0.05 Endangered species acute risk
Use at 0.95 lb ai/A 57.00 a 190.0 a 484.6 a 1615 a 0.86 0.95
Use at 1.27 lb ai/A 76.20 a 254.0 a 647.7 a 2159 a 1.15 a 1.27 a Acute risk degradates
ESA 0.15 lb ai/A 0.02 0.02 0.15 0.15 <0.01 <0.01
OA 0.36 lb ai/A 0.04 0.04 0.37 0.37 0.01 0.01

a Equals or exceeds LOC of 1



### 37

### 5.2.1.2 AgDrift

AgDrift was used to estimate clearan ce distances based on spray drift alone 2 

### . Using estimated point deposition of S-metolachlor from the AgDrift Tier I analysis, plant RQs were calculated using both seedling emer gence and vegetative vigor endpoints ( Table

23 ). For the seedling emergence endpoint, groun d applications of S- metolachlor at both

rates clear the acute risk LOC at < 300 ft, but do not fall below the endangered species LOC until >600 ft. For ground applications, bot h endangered species RQs and acute risk RQs are below the LOC at 100 ft using the vegetative vigor endpoint.

Table 23 Required Distance from Application to Fall Below LOC

Clearance Distance (ft) Application Method Application Rate (lb ai/A) Acute LOC Endangered Species LOC Based on seedling emergence (monocot, guideline data)

0.95 250 > 600 Ground (low boom) 1.27 300 > 600 Based on vegetative vigor (monocot guideline data)

0.95 10 100 Ground (low boom) 1.27 60 100



### 5.2.2 Avian RQ Summary

No acute or chronic risk LOCs are exceeded for birds, at any application rate ( Table 24 ). Acute endangered species risk LOCs are exceeded for small birds (20g) eating short grass at the 0.95 lb ai/A application rate (RQ 0.14). At the higher application rate, endangered species acute risk LOCs are exceeded for he rbivorous and insecti vorous small birds (20g, RQ 0.11-0.14).

Table 24 Avian RQ Summary

Acute dose-based RQs 1 Acute dietarybased RQs 1 Chronic
RQs Risk quotients based on Kenaga upper bound EECs 20g 100g 1000g All birds All birds Application Rate 0.95 lb ai/A Short grass <0.14 b <0.06 <0.02 <0.05 0.57 Tall grass <0.07 <0.03 <0.01 <0.02 0.26 Broadleaf plants/small insects <0.08 <0.04 <0.01 <0.03 0.32 Fruits/pods/seeds/lg insects <0.01 <0.01 <0.01 <0.01 0.04 Application Rate 1.27 lb ai/A Short grass <0.19 b <0.09 <0.03 <0.06 0.76 Tall grass <0.09 <0.04 <0.01 <0.03 0.35 Broadleaf plants/small insects <0.11 b <0.05 <0.02 <0.03 0.43 Fruits/pods/seeds/lg insects <0.01 <0.01 <0.01 <0.01 0.05

1 LD 50 /LC 50 values only established as greater than(>) a particular concentration, so RQs are reported as less than (<) values

a Equals or exceeds acute risk LOC (0.5)

b Equals or exceeds endangered species acute risk LOC (0.1)

c Equals or exceeds chronic risk LOC (1.0)

2 Locations near the use site that receive runoff shoul d be evaluated on the basi s of total loading (runoff plus spray drift).



### 38

### 5.2.3 Small Mammal RQ Summary

No acute risk or endangered species acute risk LOCs are exceeded at any application rate ( Table 25 ). Chronic risk LOCs are exceeded for all size classes of herbivores at both application rates, using the dose-based estima tions. Chronic risk LOCs are also exceeded for small (15g) and medium (35g) insectivores . Chronic LOCs are exceeded at the 1.27 lb ai/A application rate for mammals eati ng short grass using th e dietary-based RQs.

Table 25 Small Mammal RQ Summary

Acute
dose-based RQs Chronic
dose-based RQs Chronic dietary-based
RQs Risk Quotients based on Kenaga upper bound EEC 15 g 35 g 1000 g 15 g 35 g 1000 g All mammals Application Rate 0.95 lb ai/A Short grass 0.04 0.03 0.02 6.59 c 5.63 c 3.02 c 0.76 Tall grass 0.02 0.01 0.01 3.02 c 2.58 c 1.38 c 0.35 Broadleaf plants/
small insects 0.02 0.02 0.01 3.71 c 3.17 c 1.70 c 0.43

Fruits/pods/seeds/ lg insects <0.01 <0.01 <0.01 0.41 0.35 0.19 0.05

Seeds (granivores) <0.01 <0.01 <0.01 0.09 0.08 0.04 Application Rate 1.27 lb ai/A Short grass 0.05 0.04 0.02 8.81 c 7.53 c 4.04 c 1.02 c Tall grass 0.02 0.02 0.01 4.04 c 3.45 c 1.85 c 0.47 Broadleaf plants/
small insects 0.03 0.02 0.01 4.96 c 4.24 c 2.27 c 0.57

Fruits/pods/seeds/ lg insects <0.01 <0.01 <0.01 0.55 0.47 0.25 0.06

Seeds (granivores) <0.01 <0.01 <0.01 0.12 0.10 0.06

a Equals or exceeds acute risk LOC (0.5)

b Equals or exceeds endangered species acute risk LOC (0.1)

c Equals or exceeds chronic risk LOC (1.0)



### 5.2.4. Terrestrial Insects

EFED currently has no standard procedure for calculating RQs for terrestrial insects. However, guideline data are available for honeybee toxicity, and the Kenaga residue (as modified by Fletcher, et al. (1994) estimates can be used as a rough approximation of exposure. The honeybee acute contact NOAEL is 200 μ g/bee. If the mass of a honeybee is assumed to be approximately 0.08g, this would correlate to approximately 2,500 μ g/g. Residue estimates for the higher (1.27 lb ai/A) application rate range from 25 μ g/g (large insects) to 224 μ g/g (small insects). Thus, it appears th at terrestrial insects that react to

acute contact with S-metolachlor in a fashi on similar to honeybees are unlikely to be at risk. Given currently availabl e data and models, EFED is una ble to evaluate the potential

effects of an oral dose.

39

### 6. Risk Description

The risk description is presen ted in terms of the type of ecosystem assessed (aquatic or terrestrial). Where appropriate, the descrip tion is further subdivided into taxa and application rate. A separate section is included to summarize potential effects on endangered species.

6.1 Aquatic Risk

Aquatic risk was evaluated based on EECs fo r the S-metolachlor, and the two major degradates. Several differe nt scenarios were run in PRZM-EXAMS to determine how

concentrations of S-metol achlor in the receiving wa ter body might vary based on application rates, and site soil and meteorological conditions . Soil organic matter in the scenario was used to determine application rate, in accordance with label directions

6.1.1 Aquatic Plants

Aquatic plants, both algal and va scular are at risk based on a ll scenarios evaluated. Acute risk RQs for algae ranged from 1.21-4.39. Alg ae are important as a primary producer in many aquatic systems. The specific effect S-metolachlor may have on the alga is difficult to predict, and may vary widely, de pendent on the type of receiving waters. The EXAMS water body is static, with no downstr eam dilution effects. The 21-day and in some cases the 60-day EECs exceed the acute risk LC 50 

### of the most sensitive algal species. Thus, there could be effects such as a 1-2 month depression of algal growth in ponds and other still water bodies such as ve rnal pools receiving S- metolachlor input. Alternatively, there may instead be a shift to more resistant algal spec ies. The effect an algal community shift would have on higher or ganisms is difficult to predict. However, if the selection pressure leads to greater concentrations of algal species that are less palatable, such as blue-green algae, it could result in reduced survival and/or growth in aquatic organisms dependent on the algal food chain.

In some use scenarios (CA lettuce and FL peppers), the non-endangered aquatic plant LOC is exceeded for vascular aquatic plants, and in all scenarios the endangered species LOC is exceeded. In aquatic systems, vasc ular plants generally serve a structural function, providing cover for various organisms ra ther than serving as a food source. In certain aquatic systems, vegetated zones cont ain the greatest diversity of organisms and the greatest biomass per unit area. Loss of th ese vegetated areas, and/ or conversion to an alternative dominant plant could ch ange the overall biotic community.

6.1.2 Aquatic Animals

On an acute basis, S-metolachlor is slightly to moderately toxic to fish and aquatic

invertebrates. Based on all scenarios eval uated, no acute LOCs were exceeded or approached for these organisms, and use of S-metolachlor at the proposed rate appears unlikely to cause any direct effects on gr owth, reproduction, or su rvival. While EFED does not have a procedure for evaluating behavioral or biochemical endpoints,

40

### concentrations at which effects are noted can be compared to EECs. All peak EECs were an order of magnitude lower than the cellula r damage endpoint for the American bullfrog. In two scenarios (CA lettuce 0.035 mg/L, FL peppers 0.024 mg/L), the 1-in-10 year peak

concentration of S-metolachlor was close to or exceeded the concentration at which

behavioral modifications were noted in the rusty crayfish (0.027 mg/L). Whether the same effects might occur in a natural setti ng is unknown, as is whether the effects would have an impact on the survival of the organism.

6.2 Terrestrial Risk

The terrestrial risk description is divided into two sections: plants and animals. Risk to plants is evaluated based on RQ s generated from guideline test toxicity data and exposure estimates from TerrPlant and AgDrift. Risk to animals is evaluated based on guideline toxicity test data and exposu re estimates from TREX.

6.2.1 Plants

As is expected with an herbic ide, non-target plants are the organisms with the greatest potential for effects. All total loading (runoff plus drift) acute risk RQs calculated using TerrPlant exceeded the LOC by 1-2 orders of magnitude at both use rates. Exceedences of the endangered species acute risk LOCs we re generally in the range of 1-3 orders of magnitude. In some cases, endangered species LOCs were exceeded on the basis of spray drift alone.

Ecologically, terrestrial plants are important to wildlife both as a food source and a structural habitat component. Removal a nd/or modification of the terrestrial plant community could change both the number and type of organisms it can support.

The AgDrift model was used to estimate the distance required for expected spray drift

concentrations to fall below the LOC. Estim ates are based on Tier I modeling, which is non-site-specific. Deposition of the pesticid e is dependent mainly on application rate, application method, droplet size, and distance from the source. Clearance distances were estimated based on both seedling emergence data , and vegetative vigor data. Currently, the S-metolachlor label (Dual II Magnum®, EPA Reg # 100-818, Syngenta) contains a 400-ft buffer requirement for sensitive plants . Based on the most sensitive endpoint, the seedling emergence, clearance distances fo r the non-endangered plants are 250-300 ft,

but clearance distances for e ndangered plants are >600 ft.

6.2.2 Animals (Birds, Mammals, Insects)

Generally, use of S-metolachlor at the proposed rates appears to pose relatively low risk

to terrestrial animals on an acute basis. No acute risk LOCs were exceeded for either birds or mammals, although there were exceeden ces of the endangered species acute risk

LOC for herbivorous and insectivorous small birds (20g) and herbivorous medium-sized birds (100g). However, the guideline te sts did not establis h a definitive LC 50 

### , instead

41

### only determining a “greater than” value, so there is some uncertainty regarding the potential risk to birds, which coul d be over-estimated by existing data.

Chronic risk exceedances for several size clas ses and guilds of mammals using the dosebased RQs indicates the potential for effect s similar to these noted in the guideline studies. Chronic dietary-based RQs exceed the LOC only for mammals eating short grass. Chronic effects appear to be mostly reduced quantity and viability of offspring.

Based on acute contact tests for honey bees, S-metolachlor does not appear to pose a

threat to terrestrial insects.

6.3 Endangered Species

For a screening level risk assessment, EFED determines what endangered species may be affected by using the LOCATES database to search for organisms which are present in the same county as the crop being assessed. Po tential direct effect s are evaluated based on taxa which have RQs that exceed the LOC. For terrestrial organisms, evaluation of potential effects is also based on the organi sm’s size and diet. Organisms at risk for

indirect effects include ones whose:

1) habitat may have been altered by the action, or 2) primary food source may have been affected.

6.3.1 Aquatic Endangered Species

Direct Effects

No aquatic LOCs for animals were exceeded. Endangered species LOCs were exceeded for aquatic vascular plants. Table 26 show the number of endangered or threatened plants located in the same counties where pumpki ns and squash are grown. A species list is included in Appendix G.

Indirect Effects

Indirect effects could include modification of the food chain due to changes in the quantity and/or composition of the algal co mmunity. Based on available data, green algae appear to be more sensitive to the eff ects of S-metolachlor than blue-green algae or diatoms. The magnitude and potential impact of such a shift is difficult to predict on a non-site specific basis. However, certain ecosystems characterized by relatively low volume to surface area and still waters ( e.g., vernal pools) may be more susceptible to these types of effects. These locations provide important habitat for amphibians.

Vascular aquatic plants also may be affect ed by runoff of S-metolachlor into waters adjacent to the use site. In aquatic systems, vascular plants generally serve a structural function, providing a refuge for small fish and habitat for some type s of crustaceans and

42

### gastropods. Reduction of the vegetated areas and/or shifts to an alternative dominant species could affect the viability of other organisms in the waterbody.

6.3.2 Plants

Direct Effects

S-metolachlor has the potential to directly a ffect endangered plants located near the use site. The most vulnerable plants are those th at are germinating, especially if they are exposed to S-metolachlor in both runoff and drift. Proximity to the use site will affect

risk. Table 26 shows the number of endangered or th reatened plants are located in the same counties where pumpkins and squash ar e grown. A species list is included in Appendix G.

43Table 26 Endangered Plants by State and Crop

Pumpkin Squash State Monocot Dicot Other Monocot Dicot Other

Alabama 2 9 2 2 9 2

Arizona 3 11 0 3 16 0

Arkansas 0 3 0 0 3 0
California 15 153 2 15 153 2
Colorado 1 3 0 1 5 0
Connecticut 1 1 0 1 1 0

Delaware 2 0 0 2 0 0

Florida 1 10 1 2 43 2 Georgia 5 6 0 4 8 3

Hawaii 22 233 12 22 233 12

Idaho 0 3 0 0 3 0

Illinois 1 7 0 1 7 0

Indiana 1 4 0 0 3 0

Iowa 2 3 1 2 3 1

Kansas 1 1 0 1 1 0 Kentucky 0 9 0 0 6 0

Lousiana 0 1 1 0 1 0

Maine 2 1 0 2 1 0 Maryland 2 4 0 2 4 0

Massachusetts 2 1 0 2 1 0 Michigan 3 4 1 3 4 1

Minnesota 2 2 0 2 2 0 Mississippi 0 1 0 0 1 1

Missouri 1 7 0 1 6 0

Montana 0 2 0 0 2 0

Nebraska 1 1 0 1 1 0

Nevada 0 1 0 0 8 0 New Hampshire 1 1 0 1 1 0 New Jersey 3 2 0 3 2 0

New Mexico 0 11 0 0 12 0

New York 1 4 1 1 4 1
North Carolina 5 19 1 5 19 1

North Dakota 1 0 0 1 0 0
Ohio 2 4 0 2 4 0
Oklahoma 0 0 0 1 0 0 Oregon 1 9 0 2 9 0 Pennsylvania 2 0 0 2 0 0

Rhode Island 1 1 0 1 1 0
South Carolina 5 11 1 6 12 2
South Dakota 1 0 0 1 0 0

Tennessee 1 16 2 1 13 1

Texas 0 13 0 2 20 0

Utah 1 15 0 1 16 0

Vermont 1 1 0 1 1 0 Virginia 4 12 0 4 11 0 Washington 0 5 0 0 7 0 West Virgina 1 4 0 1 4 0

Wisconsin 2 4 0 2 4 0 Wyoming 0 1 0 0 0 0



### 44

### Indirect Effects Pesticide-mediated indirect effects to plants are usually the loss of an important pollinator or dispersal species. Some endangered plan t species may require the presence of other non-endangered plant species to create a suitable habitat. S-metol achlor effects on the habitat plants could constitute an indirect e ffect, but without detailed information on the plant’s life history and distri bution, EFED is unable to even qualitatively evaluate this type of effect, although they could occur.

6.3.3 Birds, Reptiles & Amphibians

Direct effects (Birds)

A search was conducted on LOCATES to determ ine what endangered birds are reported to occur in the same counties in which pum pkins and squash are grown. A total of 71 bird species were reported. These organisms were sorted by dietary habits and size classes to determine which were in categorie s with exceedences of the LOCs. A full list of specific organisms and reasons why they were not retained as a species of concern is included in Appendix G. A total of 26 species ( Table 27 ) remained in categories potentially at direct risk from S-metolachlor.

45Table 27 Endangered birds potentially at risk from s-metolachlor

Species Size
class 1.27
lb ai/A 0.95
lb ai/A
Common name Latin name A C A C

Invertivores ‘Akepa, Hawaii Loxops coccineus coccineus S * * ‘Akepa, Maui Loxops coccineus ochraceus S * *

‘Akia Pola’au Hemignathus munroi S * * Creeper, Hawaii Oreomystis mana S * * Creeper, Molokai Paroreomyza flammea S * * Creeper, Oahu Paroreomyza maculata S * * Elepaio, Oahu Chasiempis
sandwichensis ibidis S * *

Finch, Laysan Telespyza cantans S * * Finch, Nihoa Telespyza ultima S * * Flycatcher,
Southwestern Willow Empidonax traillii extimus S * *

Gnatcatcher, Coastal
California Polioptila
californica californica S * *

Millerbird, Nihoa Acrocephalus familiaris kingi S * *

Nuku Pu’u Hemignathus lucidus S * * Parrotbill, Maui Psuedonestor xanthophrys S * * Plover, Piping Charadrius melodus S * * Plover, Western Snowy Charadrius alexandrinus
nivosus S * *

Po’ouli Melamprosops phaeosoma S * * Scrub-jay, Florida Aphelocoma coerulescens S * * Starling, Ponape Mountain Aplonis pelzelni S * *

Tern, California Least Sterna antillarum browni S * * Tern, Interior Least Sterna antillarum S * * Vireo, Least Bell’s Vireo belli pusillus S * * Warbler,
Golden-cheeked Dendroica chrysoparia S * *

Warbler, Kirtland’s Dendroica kirtlandii S * * Warbler, Bachman’s Vermivora bachmanii S * * Woodpecker,
Red-cockaded Picoides borealis S * *

A- Acute, C-Chronic, * - risk



### Direct effects (Reptiles and Amphibians)

A search was conducted on LOCATES to de termine what endangered reptiles and amphibians are reported to occur in the same counties in which pumpkins and squash are grown. A total of 29 reptiles and 16 amphibi ans were reported. These organisms were sorted by dietary habits to determine which were in categories with exceedences of the LOCs. Amphibians with no terrestrial phase were excluded. A full list of specific organisms and reasons why they were not retain ed as a species of concern are listed in Appendix G. A total of 26 species ( Table 28 ) remained in categorie s potentially at direct

risk from S-metolachlor.

46Table 28 Endangered reptiles and amphibians potentially at risk from S-metolachlor

Species Size
class 1.27
lb ai/A 0.95
lb ai/A
Common name Latin name A C A C

Herbivores Tortoise, Desert Gopherus agassizii N/A * * Tortoise, Gopher Gopherus polyphemus N/A * * Turtle, Alabama
Red-belllied Pseudemys
alabamensis N/A * *

Invertivores Frog, California Red-legged Rana aurora draytonii N/A * *

Frog, Chriricahua Leopard Rana ciricahuensis N/A * *

Frog, Mountain Yellow-legged Rana muscosa N/A * *

Lizard, Blunt-nosed Leopard Gambelia silus N/A * *

Lizard, Coachella Valley Fringe-toed Uma inornata N/A * *

Lizard, Island Night Xantusia riversiana Salamander, California Tiger Ambystoma
californiense N/A * *

Salamander, Cheat
Mountain Plethodon nettingi N/A * *

Salamander, Desert
Slender Batrachoseps aridus N/A * *

Salamander, Flatwoods Ambystoma cingulatum N/A * * Salamander, Red Hills Phaeognathus hubrichti N/A * * Salamander, Santa Cruz Long-toed Ambystoma macrodactylum

croceum N/A * *

Salamander,
Shenandoah Plethodon shenandoah N/A * *

Salamander, Sonora Tiger Ambystoma tigrinum
stebbinsi N/A * *

Skink, Blue-tailed Mole Eumeces egregious
lividus N/A * *

Skink, Sand Neoseps reynoldsi N/A * * Toad, Arroyo
Southwestern Bufo californicus (=microscaphus) N/A * *

Toad, Houston Bufo houstonensis N/A * * Turtle, Northern Bog Clemmys muhlenbergii N/A * * Turtle, Flattened Musk Sternotherus depressus N/A * *Turtle, Plymouth Redbellied Pseudemys rubriventris bangsi N/A * *

Turtle, Ringed Sawback Graptemys oculifera N/A * * Turtle, Yellow-blotched Map Graptemys
flavimaculata N/A * *

A- Acute, C-Chronic, * - risk, NA – Not app licable (allometric equations used for birds are not expected to be applicable to reptiles)



### 47

### Indirect Effects (Birds , Reptiles and Amphibians) The most likely indirect effect on birds, reptiles, and amphibians is modification of habitat as a result of damage to plants. The habitat modification could include reduced food supply, locations for nesting or burro wing, and/or reduced cover for predator avoidance. EFED is currently unable to eval uate the likelihood or magnitude of such an

effect.

6.3.4 Mammals

Direct effects

A search was conducted on LOCATES to de termine what endangered mammals are reported to occur in the same counties in wh ich pumpkins and winter squash are grown. A total of 55 mammals were reported. These organisms were sorted by dietary habits and

size classes to determine which were in cat egories with exceedences of the LOCs. A full list of specific organisms and reasons why they were not retained as a species of concern are listed in Appendix G. A total of 12 species ( Table 29 ) remained in categories potentially at direct risk from S-metolachlor.

Table 29 Endangered mammals potentially at risk from S-metolachlor

Species Size
class 1.27
lb ai/A 0.95
lb ai/A
Common name Latin name A C A C

Herbivores Mountain Beaver,
Point Arena Aplodontia rufa nigra L * *

Mouse, Salt Marsh
Harvest Reithrodontomys
raviventris M * *

Prairie Dog, Utah Cynomys parvidens L * * Rabbit, Pygmy Brachylagus idahoensis M * * Rabbit, Riparian
Brush Sylvilagus bachmani riparius L * *

Vole, Florida Salt
Marsh Microtus pennsylvanicus dukecampbelli M * *

Vole, Hualapai
Mexican Microtus mexicanus hualpaiensis M * *

Invertivores Bat, Gray Myotis grisescens S * * Bat,Hawaiian Hoary Lasiurus cinerus

semotus S * *

Bat, Indiana Myotis sodalis S * * Bat, Ozark Big-eared Corynorhinus (=Plecotus) townsendii ingens S * *

Shrew, Buena Vista
Lake Ornate Sorex ornatus relictus S * *

A- Acute, C-Chronic, * - risk



### 48

### Indirect Effects (Mammals) The most likely indirect effect on mammal is modification of habitat as a result of damage to plants. The habitat modificati on could include reduced food supply, locations for nesting or burrowing, and/or reduced cover for predator avoidance. EFED is currently unable to evalua te the likelihood or magnit ude of such an effect.

6.3.5 Probability of Individual Effects

Toxicity data available for birds and mammals does not support evaluation of potential individual mortality based on a probit dose-response relationship.

49

### References

Eckermann C, B. Matthes, M. Nimtz, V. Reiser , B. Lederer, P. Boger P, J. Schroder. (2003). Covalent binding of chloroacetamide he rbicides to the active site cysteine of plant type III polyketide synthases. Phytochemistry 64 (6):1045-54.

Fletcher, J.S., J.E. Nellesson and T. G. Pfl eeger. 1994. Literature review and evaluation of the EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants. Environ. Tox. And Chem . 13(9):1383-1391

Jablonkai I. (2003). Alkylating reactivity a nd herbicidal activity of chloroacetamides. Pest Manag Sci

. 59 (4):443-50.

Junghans, M., T. Backhaus, M. Faust, M. Scholze, L.H. Grimme. (2003). Predictability

of combined effects of ei ght chloroacetanilide herbic ides on algal reproduction. Pest Manag Sci. 59 (10):1101-10.

Pillai P., D.E. Davis, B. Truelove (1979). E ffects of metolachlor on germination, growth, leucine uptake, and protein synthesis. Weed Science 27 (6):634-637.

Rossini L., C. Frova, M. E. Pè, L. Mizzi, M. Sari Gorla. (1998). Alachlor Regulation of

Maize Glutathione S-Transferase Genes. Pesticide Biochemistry and Physiology

. 60 (3):205-211.

Schmalfuss J., B. Matthes, K. Knuth, P. Böger (2000). Inhibition of Acyl_CoA Elongation by Chloroacetamide Herbicides in Microsomes from Leek Seedlings. Pesticide Biochemistry and Physiology

, 67 (1):25-35.

U.S. Patent and Trademark Office. (1991). Patent No 5,002,606. Optically active N- (1'methy-2'methoxyethyl)-N-chloroacetyl-2-ethyl -6-methylaniline as herbicide. Filed December 7, 1984.

Zimdahl, R.L. (1993). Fundamentals of Weed Science. Academic Press. San Diego

California USA.

50

### ECOTOX References

6797 Mayer, FLJ and Ellersieck, MR. (1986). Manual of Acute Toxicity: Interpretation and Data Base for 410 Chemicals and 66 Species of Freshwater Animals . Resour. Publ. No. 160, U.S. Dept of Interior, Fish & Wildlife Service, Washington, DC, 505 p.

19186 Day, KE and Hodge V. (1996). The Toxicity of the Herbicide Metolachlor, Some

Transformation Products and a Commercial Safener to an Alga (Selenastrum capricornutum), a Cyanophyte. Water Qual. Res. J. Can. 31:197-214.

19461 Fairchild, JF, Ruessler, DS, Have rland, PS, and Carlson, AR. (1997). Comparative Sensitivity of Selenastrum capricornutum and Lemna minor to Sixteen

Herbicides. Arch. Environ. Contam. Toxicol , 32:353-357.

20274 Clements, C, Ralph, S., and Petras, M. (1997). Genotoxicity of Select Herbicides

in Rana catesbeiana Tadpoles using the Alkaline Single-Cell Gel DNA Elcetrophoresis (Comet) Assay. Environ. Mol. Mutagen . 29:277-288.

66376 Osano, O, Admiraal, W, and Otieno, D. (2002). Developmental Disorders in Embryos of the Frog Xenopus laevis Induced by Chloroacetanilide Herbicides and Their Degradation Products. Environ. Toxicol. Chem . 21:375-379.

67700 Ronco, A, Sobrero, C, Grassi, Vkaminski, L, Massolo, L, and Mina, L. (2000) WaterTox Bioassy Intercalibration Ne twork: Results from Argentina. Environ. Toxicol.

15:287-296.

68515 Wolfe, MC and Moore, PA. (2002). Eff ects of the Herbicide Metolachlor on the Perception of Chemical Stimuli by Oronectes rusticus. J.N.Am. Benthol. Soc 21:457-74.

73233 Hatton, PJ, Dixon, D, Cole, DJ, Edwards, R. (1996). Glutathione Transferase Activities and Herbicide Selectivity in Ma ize and Associated Weed Species. Pestic.

Sci.46: 267-275.

73249 Warren, SL and Skroch, WA. (1991). Evalua tion of Six Herbicides for Potential

use in Tree Seed Beds. J. Environ. Hortic . 9:160-163.

73251 Hood, LR and Klett, JE. (1992). Preeme rgent Weed Control in Container-Grown Herbaceous and Woody Plants. J. Environ. Hortic . 10:8-11.

51

## Appendix A Aquatic Exposu re PRZM-EXAMS Output

52

## Appendix B Terrestrial Animals Exposure TREX Output

53

## Appendix C Terrestrial Plant Exposu re Output (TerrPlant, AgDrift)

54

## Appendix D Aquatic RQ Calculations

55

## Appendix E Incident Database Report EIIS Output

56

## Appendix F Risk Quotient Method and Levels of Concern

57

### 58 

## Appendix G Threatened and Enda ngered Species LOCATES Output