# Risks of Pendimethalin Use to Federally Threatened California Red-legged Frog (Rana aurora draytonii )

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Pesticide Effects Determinatio n

Environmental Fate and Effects Divisio n Office of Pesticide Program s Washington, D.C. 2046 0

June 16, 200 9

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### Primary Authors:
Michael Davy, Agronomist
William P. Eckel, Ph.D., Physical Scientist

Secondary Review:
Jean Holmes, DVM,MPH Risk Assessment Process Leader

Final Review:
Tom Bailey, Ph.D., Branch Chief Environmental Risk Assessment Branch 2

2Table of Contents

1.0 Executive Summary

.......................................................................................... 1 0 2.0 Problem Formulation

........................................................................................ 1 5 2.1 Purpose

.............................................................................................................. 1 5 2.2 Scope

................................................................................................................. 1 7 2.3 Previous Assessments

....................................................................................... 1 8 2.4 Stressor Source and Distribution

...................................................................... 1 9 2.4.1 Environmental Fate Assessment

................................................................... 1 9 2.4.2 Mechanism of Action

.................................................................................... 2 1 2.4.3 Use Characterization

..................................................................................... 2 2 2.5 Assessed Species

............................................................................................... 2 8 2.5.1 Distribution

................................................................................................... 2 8 2.5.2 Reproduction

................................................................................................. 3 1 2.5.3 Diet

................................................................................................................ 3 1 2.5.4 Habitat

........................................................................................................... 3 2 2.6 Designated Critical Habitat

............................................................................... 3 3 2.7 Action Area

....................................................................................................... 3 5 2.8 Assessment Endpoints and Measures of Ecological Effect

.............................. 3 9 2.8.1 Assessment Endpoints for the CRLF

............................................................ 3 9 2.8.2 Assessment Endpoints for Designated Critical Habitat

................................ 4 1 2.9 Conceptual Model

............................................................................................. 4 3 2.9.1 Risk Hypotheses

............................................................................................ 4 3 2.9.2 Diagram

......................................................................................................... 4 3 2.10 Analysis Plan

.................................................................................................... 4 5 2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model

.............. 4 6 2.10.1.1 Measures of Exposure

....................................................................... 4 6 2.10.1.2 Measures of Effect

............................................................................ 4 8 2.10.1.3 Integration of Exposure and Effects

................................................. 4 9 3.0 Exposure Assessment

....................................................................................... 4 9 3.1 Label Application Rates and Intervals

.............................................................. 5 0 3.2 Aquatic Exposure Assessment

.......................................................................... 5 1 3.2.1 Modeling Approach

...................................................................................... 5 1 3.2.2 Model Inputs

................................................................................................. 5 2 3.2.3 Results

........................................................................................................... 5 3 3.2.4 Existing Monitoring Data

............................................................................. 5 4 3.2.4.1 USGS NAWQA Surface Water Data

....................................................... 5 4 3.2.4.2 USGS NAWQA Gr oundwater Data

......................................................... 5 4 3.2.4.3 California Department of Pesticide Regulation (CPR) Data

.................... 5 5 3.2.4.4 Atmospheric Monitoring Data

.................................................................. 5 6 3.2.4.5 Spray Drift Buffer and Downstream Dilution Analysis for Action Area . 5 6 3.3 Terrestrial Animal Exposure Assessment

......................................................... 5 7 3.4 Terrestrial Plant Exposure Assessment

............................................................. 5 9 4.0 Effects Assessment

........................................................................................... 6 0 4.1 Evaluation of Aquatic Ecotoxicity Studies

....................................................... 6 2 4.1.1 Toxicity to Freshwater Fish

.......................................................................... 6 3

34.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies

............................. 6 3 4.1.1.2 Freshwater Fish : Chronic Exposure (Early Life Stage and Reproduction ) Studies

....................................................................................................... 6 4 4.1.1.3 Freshwater Fish: Sublethal Effect s and Additional Open Literatur e Information

............................................................................................... 6 4 4.1.1.4 Aquatic-phase Amphibian: Acute and Chronic Studies

.......................... 6 4 4.1. 2 Toxicity to Freshwater Invertebrates

............................................................ 6 5 4.1.2.1 Freshwater Invertebrates: Acut e Exposure (Mortality) Studies

................ 6 5 4.1.2.2 Freshwater Invertebrates: Chr onic Exposure (Reproduction) Studies

...... 6 5 4.1.2.3 Freshwater Invertebrate s: Sublethal Effects and Open Literature Data

.... 6 6 4.1. 3 Toxicity to Aquatic Plants

............................................................................ 6 6 4.1.3.1 Aquatic Plants: Laboratory Data

............................................................... 6 6 4.1.3.2 Freshwater Field Studies

........................................................................... 6 7 4. 2 Toxicity of Pendimethalin to Terrestrial Organisms

........................................ 6 7 4.2. 1 Toxicity to Birds

........................................................................................... 6 8 4.2.1.1 Birds: Acute Exposure (Mortality) Studies

............................................... 6 9 4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies

...................... 6 9 4.2.1.3 Birds: Open Literature Studies

.................................................................. 6 9 4.2. 2 Toxicity to Mammals

.................................................................................... 6 9 4.2.2.1 Mammals: Acute Exposure (Mortality) Studies

....................................... 7 0 4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies

............... 7 0 4.2.2.3 Mammals: Open Literature Studies

.......................................................... 7 0 4.2. 3 Toxicity to Terrestrial Invertebrates

............................................................. 7 0 4.2.3.1 Terrestrial Invertebrates: Acute Exposure (Mortality) Studies

................. 7 0 4.2.3.2 Terrestrial Invertebrates: Open Literature Studies

.................................... 7 1 4.2. 4 Toxicity to Terrestrial Plants

........................................................................ 7 1 4. 3 Use of Probit Slope Response Relation ship to Provide Information on th e Endangered Species Levels of Concern

............................................................ 7 2 4. 4 Incident Database Review

................................................................................ 7 3 4.4. 1 Terrestrial Incidents

...................................................................................... 7 3 4.4. 2 Plant Incidents

............................................................................................... 7 4 4.4. 3 Aquatic Incidents

.......................................................................................... 7 4 5.0 Risk Characterization

........................................................................................ 7 6 5. 1 Risk Estimation

................................................................................................. 7 6 5.1. 1 Exposures in the Aquatic Habitat

................................................................. 7 6 5.1.1.1 Direct Effects to Aquatic-Phase CRLF

..................................................... 7 6 5.1.1.2 Indirect Effects to Aquatic-Ph ase CRLF via Reduction in Prey (nonvascular aquatic plants, aquatic invertebrates, fish, and frogs)

................. 7 8 5.1.1.3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary Productivity (Freshwater Aquatic Plants)

................................................. 8 0 5.1. 2 Exposures in the Terrestrial Habitat

............................................................. 8 0 5.1.2.1 Direct Effects to Terrestrial-phase CRLF

................................................. 8 0 5.1.2.2 Indirect Effects to Terrestrial -Phase CRLF via Reduction in Pre y (terrestrial invertebrate s, mammals, and frogs)

........................................ 8 3 5.1.2.3 Indirect Effects to CRLF via Reduc tion in Terrestrial Plant Community (Riparian and Upland Habitat)

.................................................................. 8 6

45.1.3 Primary Constituent Elements of Designated Critical Habitat

..................... 8 8 5.1.3.1 Aquatic-Phase (Aquatic Breeding Habitat and Aquatic Non-Breedin g Habitat)

..................................................................................................... 8 8 5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat)

....................... 8 9 5.2 Risk Description

............................................................................................... 9 0 5.2.1 Direct Effects

................................................................................................ 9 3 5.2.1.1 Aquatic-Phase CRLF

................................................................................ 9 3 5.2.1.2 Terrestrial-Phase CRLF

............................................................................ 9 4 5.2.2 Indirect Effects (via Re ductions in Prey Base)

............................................. 9 8 5.2.2.1 Algae (non-vascular plants)

...................................................................... 9 8 5.2.2.2 Aquatic Invertebrates

................................................................................ 9 9 5.2.2.3 Fish and Aquatic-phase Frogs

................................................................. 10 0 5.2.2.4 Terrestrial Invertebrates

.......................................................................... 10 0 5.2.2.5 Mammals

................................................................................................. 10 1 5.2.2.6 Terrestrial-phase Amphibians

................................................................. 10 2 5.2.3 Indirect Effects (via Habitat Effects)

.......................................................... 10 2 5.2.3.1 Aquatic Plants (Vascular and Non-vascular)

.......................................... 10 2 5.2.3.2 Terrestrial Plants

..................................................................................... 10 3 5.2.4 Effects to Designated Critical Habitat

........................................................ 10 4 5.2.4.1 Aquatic-Phase PCEs

............................................................................... 10 4 5.2.4.2 Terrestrial-Phase PCEs

........................................................................... 10 5 5.2.5 Spatial Extent of Potential Effects

.............................................................. 10 6 5.2.5.1 Spray Drift

............................................................................................. 10 6 5.2.5.2 Downstream Dilution Analysis

.............................................................. 10 8 5.2.5.3 Overlap between CRLF habitat and Sp atial Extent of Potential Effects 10 8 6.0 Uncertainties

.................................................................................................. 11 1 6.1 Exposure Assessment Uncertainties

............................................................... 11 1 6.1.1 Maximum Use Scenario

.............................................................................. 11 1 6.1.2 Aquatic Exposure Modeling of Pendimethalin

........................................... 11 1 6.1.3 Usage Uncertainties

.................................................................................... 11 3 6.1.4 Terrestrial Exposure Modeling of Pendimethalin

....................................... 11 3 6.1.5 Spray Drift Modeling

.................................................................................. 11 4 6.1.6 Volatility

..................................................................................................... 11 5 6.1.7 Bioaccumulation

........................................................................................ 11 5 6.2 Effects Assessment Uncertainties

................................................................... 11 6 6.2.1 Age Class and Sensitivity of Effects Thresholds

........................................ 11 6 6.2.2 Use of Surrogate Species Effects Data

....................................................... 11 6 6.2.3 Sublethal Effects

......................................................................................... 11 6 6.2.4 Location of Wildlife Species

....................................................................... 11 7 7.0 Risk Conclusions

............................................................................................ 11 7 8.0 References

....................................................................................................... 12 1

5List of Tables

Table 1-1 Effects Determination Summary for Pendimethalin Use and the CRLF

......... 1 3 Table 1-2 Effects Determination Summary for Pendimethalin Use and CRLF Critica l Habitat Impact Analysis

.................................................................................. 1 3 Table 2-1 Summary of PendimethalinEnvironmental Fate Properties

............................ 2 0 Table 2-2 Pendimethalin Uses Assessed for the CRLF

.................................................... 2 2 Table 2-3 Summary of California Department of Pesticide Registration (CDPR ) Pesticide Use Reporting (PUR) Data from 1994 to 2006 for Currentl y Registered Pendimethalin Uses: By County

................................................... 2 6

Table 2-5 Summary of Assessment Endpoints and Measures of Ecological Effect fo r Table 2-4 Assessment Endpoints and Measures of Ecological Effects

....................... 4 0

Primary Constituent Elements of Designated Critical Habitata

... ................... 4 2 Table 3-1 Pendimethalin Uses, Scenarios, and Application Information for the CRL F risk assessment 1

... ........................................................................................... 5 0 Table 3- 2 Summary of PRZM/EZAMS Envi ronmental Fate Data Used for Aquati c Exposure Inputs for Pendimethalin E ndangered Species Assessment for th e CRLF1

... .......................................................................................................... 5 2 Table 3-3 Aquatic EECs ( μ g/L) for Pendimethalin Uses in California

............................ 5 3 Table 3-4 Input Parameters for Foliar Applic ations Used to Derive Terrestrial EECs fo r

Table 3-5 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-base d

Table 3-6 EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via Effects t o

Table 3-7 TerrPlant Inputs and Resulting EECs for Plants Inhabiting Dry and Semi

Pendimethalin with T-REX

............................................................................. 5 7

Exposures of the CRLF and its Prey to Pendimethalin

................................... 5 8

Terrestrial Inverteb rate Prey Items

................................................................. 5 8

aquatic Areas Exposed to Pendime thalin via Runoff and Drift

...................... 5 9 Table 4-1 Freshwater Aquatic Toxi city Profile for Pendimethalin

.................................. 6 2 Table 4-2 Categories of Acute Toxicity for Fish and Aquatic Invertebrates

.................... 6 3 Table 4-3. Terrestrial Toxici ty Profile for Pendimethalin

............................................... 6 7 Table 4-4 Categories of Acute Toxic ity for Avian and Mammalian Studies

................... 6 8 Table 4-5 Non-target Te rrestrial Plant Seedling Emergence and Vegetative Vigo r Toxicity (Tier II) Data

.................................................................................... 7 1 Table 5-1 Summary of Direct Effect RQs afor the Aquatic-phase CRLF

........................ 7 7

6Table 5-2 Summary of RQs Used to Estimate In direct Effects to the CRLF via Effects t o Non-Vascular Aquatic Plants a(diet of CRLF in tadpol e life stage and habitat of aquatic-phase CRLF)

.................................................................................. 7 8 Table 5-3 Summary of Acute and Chronic RQs aUsed to Estimate Indirect Effects t o the CRLF via Direct Effects on Aquati c Invertebrates as Dietary Foo d Items (prey of CRLF juveniles an d adults in aquatic habitats)

................ 7 9 Table 5-4 Summary of RQs Used to Estimate In direct Effects to the CRLF via Effects t o Vascular Aquatic Plants (hab itat of aquatic-phase CRLF) a

... ......................... 8 0 Table 5-5 Summary of Acute RQs* Used to Es timate Direct Effects to the Terrestrial

phase CRLF

.................................................................................................... 8 1 Table 5- 6 Summary of Chronic RQs* Used to Estimate Direct Effects to the Terrestrial

phase CRLF

.................................................................................................... 8 2 Table 5- 7 Summary of RQs Used to Estimate Indirect Effects to the Terrestrial-phas e CRLF via Direct Effects on Terrestrial Invertebrates as Dietary Food Items 8 3 Table 5- 8 Summary of Acute and Chronic RQs* Used to Estimate Indirect Effects to th e Terrestrial-phase CRLF via Direct E ffects on Small Mammals as Dietary Food Items

...................................................................................................... 8 5 Table 5- 9 RQs* for Monocots Inhabiting Dry and Semi-Aquatic Areas Exposed t o Pendimethalin via Runoff and Drift

................................................................ 8 6 Table 5-10 RQs* for Dicots Inhabiting Dry and Semi-Aquatic Areas Exposed t o Pendimethalin via Runoff and Drift

................................................................ 8 7 Table 5-11 Risk Estimation Summary for Pendime thalin - Direct and Indirect Effects t o CRLF

............................................................................................................... 9 0 Table 5-12 Risk Estimation Summary for Pendi methalin – PCEs of Designated Critica l Habitat for the CRLF

...................................................................................... 9 1 Table 5-13 Upper Bound Kenaga, Acute Terr estrial Herpetofauna Dose-Based Ris k Quotients (1 lbs a.i./a cre, 1 application)

......................................................... 9 6 Table 5-14 Upper Bound Kenaga, Acute Terres trial Herpetofauna Dose-Based Ris k Quotients (1.24 lbs a.i./acre, 1 application)

.................................................... 9 6 Table 5-15. Upper Bound Kenaga, Acute Terres trial Herpetofauna Dose-Based Ris k Quotients (1.425 lbs a.i./ acre, 1 application)

.................................................. 9 6 Table 5-16. Upper Bound Kenaga, Acute Terres trial Herpetofauna Dose-Based Ris k Quotients (6 lbs a.i./A cre, 1 application)

........................................................ 9 6 Table 5-17 RQ Comparisons among Weight Class and Applications Rates for CRL F Consuming Small Herbivore Mammal That Recently Consume d Contaminated Short Grass

.............................................................................. 9 7 Table 5-18. Range of Risk Quotients fo r Non-Target Terrestrial Plants fro m Pendimethalin Usage

.................................................................................... 10 3 Table 5-19 Summary of AgDrift Predicte d Terrestrial Spray Drift Distances

............... 10 7

7Table 5-20 Summary of AgDrift Predicted Aquatic Spray Drift Distances ................. 10 7 Table 7-1 Effects Determination Summary for Pendimethalin Use and the CRLF ...... 11 8 Table 7-2 Effects Determination Summary for Pendimethalin Use and CRLF Critica l Habitat Impact Analysis....

............................................................................ 11 9

8List of Figures

Figure 2.1 Pendimethalin Use in Total Pounds per County...

........................................... 2 4 Figure 2. 2 Recovery Unit, Core Area, Critic al Habitat, and Occu rrence Designations for CRLF... ............................................................................................................ 30 Figure 2. 3 CRLF Reproductive Events by Month... ........................................................ 3 1 Figure 2.4. Initial area of con cern, or “footprint” of poten tial use, for Pendimethalin...

. 37 Figure 2. 5 Conceptual Model for Pesticide Effects on Terrestrial Phase of the CRLF... 44 Figure 2. 6 Conceptual Model for Pesticid e Effects on Aquatic Phase of the CRLF...

.... 4 5

Appendices
Appendix A Ecological Effects Data Appendix B Multi-ai Product Analysis Pendimethalin Appendix C RQ Method and LOCs Appendix D CRLF Spatial Summary Pendimethalin Appendix E T-REX Output Appendix F TerrPlant Output Appendix G ECOTOX Bibliography Appendix H Accepted ECOTOX Data Table Appendix I HED Effects Pendimethalin Appendix J PRZM-EXAMS Output Appendix K KABAM Model Output

Attachment I. Status and Life Hist ory of the California Red-legged Frog Attachment II. Baseline Status and Cumu lative Effects for the California Red-legged Frog

9

### 1.0 Executive Summary
The purpose of this assessment is to evaluate potential direct and i ndirect effects on the California red-legged frog (Rana aurora draytonii ) (CRLF) arising from FIFRA regulatory actions regarding us e of pendimethalin on agricultural and non-agricultural sites. In addition, this assessment evaluate s whether these actions can be expected to result in effects to the species’ designatedcritical habitat. This assessment was completed in accordance with the U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS) Endangered Species Consultation Handbook (USFWS/NMFS, 1998 and procedures outlined in the Agency’s Overview Document (U.S. EPA, 2004).
The CRLF was listed as a threatened species by USFWS in 1996. The species is endemic to California and Baja California (Mexico) and inhabits both co astal and interior mountain ranges. A total of 243 streams or drainages are believed to be currently occupied by the species, with the greatestnumbers in Monterey, San Luis Obispo, and Santa Barbara counties (USFWS , 1996) in California.
The following uses are considered as part of the federal action evaluated in this assessment: alfalfa, lupine for seed, alm ond, beech nut, brazil nut, butternut, cashew, chestnut, chinquapin, filbert (hazelnut), hic kory nut, macadamia nut (bushnut), mayhaw (hawthorn), pecan, pistachio, wa lnut (English/black), calamo ndin, citron (citrus), citrus, citrus hybrids other than tangelo, grapefru it, kumquat, lemon, lime, orange, pummelo (shaddock), tangelo, tangerines, Brassica (head and stem) vegetables, broccoli, broccoli (Chinese), brussels sprouts, cabbage, cabba ge (Chinese), caulifl ower, kohlrabi, mustard cabbage (gai choy - pak-choi), corn (field, pop, sw eet), sunflower, cotton, forest trees (all species), Christmas tree plantations, apple, apricot, cherry, crabapple, fig, loquat, nectarine, peach, pear, pepino (melon pear), plum, plum (Japanese), pomegranate, prune, quince, small fruits, garlic, leek, grapes, eggpl ant, olive, onion (gr een, scallions, spring), shallot, potato (white/Irish), nonagricultural rights-of-way/fencerows/hedgerows, artichoke, asparagus, beans (dry, succulent/lima/ snap), carrot (including tops), garbanzos (including chick peas), legume vegetables, le ntils, peanuts, peas (dry, early dwarf, pigeon, southern/cowpea), pepper, strawberry, tomato, groundcherry (strawberry tomato, tomatillo), airports/landing fields, commercial/industrial lawns, golf course turf, industrial areas (outdoor), ornamental and/or shade trees, ornamental ground cover, ornamental herbaceous plants, ornamental lawns and turf, ornamental nonflowering plants, ornamental sod farm (turf), ornament al woody shrubs and vi nes, recreation area lawns, residential lawns, shelterbe lt plantings, sorghum, wheat, and rice.
Ground and aerial spray applications of pe ndimethalin (including some forms of chemigation) will potentially result in spray drift onto non-target plants, soil, and water adjacent to a treated field. Pendimethalin is expected to be persistent in the terrestrial environment and under the right conditions, may accumulate in the soil with repeated applications resulting in the potential for pe ndimethalin to reach the aquatic environment on suspended soil in runoff water. Laborator y dissipation studies in soil under aerobic

1 0conditions, demonstrate a half-life of approxi mately 72-172 days, and field dissipation studies in the Midwest similarl y had half-lives th at ranged from 84-147 days. However, field dissipation studies in Louisiana and Mississippi ha d half-lives of <20 days, demonstrating that pendimethalin can be re latively short-lived under some environmental conditions. Field half-lives less than 20 days may be due to volatilization, which has a measured half-life of 12.5 days in moist soil. In laboratory studi es, pendimethalin can photodegrade in water with a half-life of approximately 42 days. However, in the environment, pendimethalin will not be available for photodegr adation because the pendimethalin in water will tend to sorb to soil or sediment particles as indicated by K oc 's which range from 13000-29400 ml/g. Thus, pendimethalin is considered hardly mobile according to FAO classification.
Pendimethalin may accumulate in fish based on submitted data. Pendimethalin residues accumulated in bluegill sunfish exposed to 3 ppb of pendimethalin, with BCFs of 1400X for edible, 5800X for nonedible, and 5100X for whole fish. Depuration was rapid, with 87- 91% of the 14 C-residues eliminated from the fishtissues by 14 days of depuration. The major terminal degradates in terrestrial environments include several compounds formed at insignificant levels (<10 % of applie d). Therefore, no degradates are included in the definition of the chemical stressor.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF and its prey to pendimethalin are assessed separately for the two habitats. Tier-II aquatic exposure models are used to estimate high-e nd exposures of pendimethalin in aquatic habitats resulting from runoff and spray drift from different uses. Peak model-estimated environmental concentrations resulting from different pendimethalin uses range from 1.74 ppb (rights-of-way/impervious) to 16.6 μg/L (forestry) and 48 ppb (rice paddies). These estimates are supplemented with anal ysis of available California surface water monitoring data from U. S. Geological Su rvey’s National Water Quality Assessment (NAWQA) program and the California Depa rtment of Pesticide Regulation. The maximum concentration of pendimethalin reported by NAWQA for California surface waters with agricultural wate rsheds is 0.68 μg/L. This value is approximately 71 times less than the maximum model-estimated en vironmental concentration. The maximum concentration of pendimethalin reported by the California Department of Pesticide Regulation surface water database (3.5 μg/L) is roughly 14 times lower than the highest peak model-estimated environmental concentration.
To estimate pendimethalin exposures to the te rrestrial-phase CRLF, and its potential prey resulting from uses involving pendimethalin applications, the T-REX model is used for foliar uses. AgDRIFT and AGDISP models ar e also used to estimate deposition of pendimethalin on terrestrial and aquatic habi tats from aerial and ground spray drift. The TerrPlant model is used to estimate pendime thalin exposures to terrestrial-phase CRLF habitat, including plants inhabiting semi-aquatic and dry areas, resulting from uses involving foliar pendimethalin applications. The T-HERPS m odel is used to allow for further characterization of diet ary exposures of terrestrial-pha se CRLFs relative to birds.

1 1The effects determination assessment endpoints for the CRLF include direct toxic effects on the survival, reproduction, and growth of th e CRLF itself, as well as indirect effects, such as reduction of the prey base or modifi cation of its habitat. Direct effects to the CRLF in the aquatic habitat are based on toxic ity information for freshwater fish, which are generally used as a surrogate for aquatic-pha se amphibians. In the terrestrial habitat, direct effects are based on toxicity informati on for birds, which are used as a surrogate for terrestrial-phase amphibians. Given th at the CRLF’s prey items and designated critical habitat requirements in the aquatic habitat are dependant on the availability of freshwater aquatic invertebrates and aquati c plants, toxicity information for these taxonomic groups is also discussed. In the te rrestrial habitat, indi rect effects due to depletion of prey are assessed by considering eff ects to terrestrial insects, small terrestrial mammals, and frogs. Indirect effects due to modification of the terrestrial habitat are characterized by available data for terrestrial monocots and dicots.

Pendimethalin is stable to most of the e nvironmental degradation processes measured, meaning there is little production of degradates. Thus, no degr adates were considered in the assessment, which was based on parent pendimethalin alone. There was monitoring data for one possible degradate, 4-hydroxype ndamethalin, in the NAWQA data. It was not detected (less than 0.143 ppb) in 61 ground water samples, and 8 surface water samples, all taken from th e San Joaquin-Tulare Basin.
Risk quotients (RQs) are derived as quantitative estimates of potential high-end risk. Acute and chronic RQs are compared to the Agency’s levels of concern (LOCs) to identify instances where pendimethalin use within the action area has the potential to adversely affect the CRLF and its designated critical habitat via direct toxicity or indirectly based on direct eff ects to its food supply (i.e., freshwater invertebrates, algae, fish, frogs, terrestrial inverteb rates, and mammals) or hab itat (i.e., aquatic plants and terrestrial upland and riparian vegetation). Wh en RQs for each particular type of effect are below LOCs, the pesticide is determinedto have “no effect” on the CRLF. Where RQs exceed LOCs, a potential to cause adverse effects is identified, leading to a conclusion of “may affect.” If a determination is made that use of pendimethalin use within the action area “may affect” the CRLF and its designated critical habitat, additional information is consid ered to refine the potential for exposure and effects, and the best available information is used to distinguish those acti ons that “may affect, but are not likely to adversely affect” (NLAA) from those actions that are “likely to adversely affect” (LAA) the CRLF.
Based on the best available information, the Agency makes a May Affect and Likely to Adversely Affect determination for the CRLF from the use of pendimethalin. Additionally, the Agency has determined that there is the potential for effects to CRLF designated critical habitat from the use of the chemical. There is potential for direct and indirect effects to the aquatic-phase and terrestrial-phase CRLF from the use of pendimethalin. Potential effects to the habi tat of the aquatic and terrestrial phase CRLF has been determined due to effects to terres trial and aquatic non-target plants. A summary of the risk conclusions and e ffects determinations for the CRL F and its critical habitat is presented in Table 1-1 and Table 1-2. Further information on the results of the effects

1 2determination is included as part of the Ri sk Description in Section 5.2. Given the LAA determination for the CRLF and potential effects to designated critical habitat, a description of the baseline status and cumu lative effects for the CRLF is provided in Attachment 2

.
Table 1-1 Effects Determination Summary for Pendimethalin Use and the CRLF Assessment

Endpoint Effects Determination 1 Basis for Determination
Survival, growth, Potential for Direct Effects and/or reproduction of CRLF individuals LAA 1 Aquatic-phase (Eggs, Larvae, and Adults) : Acute LOCs were exceeded for fish or aquatic-phase amphibians Terrestrial-phase (Juveniles and Adults) : Acute and chronic LOCs were exceeded for birds. The available toxicity data suggest that amphibians are less sensitive than birds to pendimethalin, and considering factors such as lowe r food intake of terrestrial phase amphibians relative to birds reduces EECs and RQs, but does not reduce RQs to levels that are below LOCs. Likely to adversely affect CRLF. Potential for Indirect Effects Aquatic prey items, aquatic habitat, cover and/or primary productivity: LOC is exceeded only for non-vascular aquatic plants. RQs are below LOC for freshwater invertebrates (chronic an d acute effects) and fish or frogs (chronic and acute effects). Pendimethalin could potentially impact terrestrial and aquatic plants to an exte nt that could result in indirect effects to the CRLF or effects to critical habitat. Terrestrial prey items, riparian habitat: Chronic LOC is exceeded for mammal and birds (surrogate for frog). Pendimethalin is practically non-toxic to honeybees with no mortalities observed in testing. LOC is exceeded for terrestrial invertebrates. Uncertainty in toxicity to insects from EEC that is above hi ghest bee concentration tested does not preclude potential risk. Pendimethalin may adversely affect insects. Acute LOCs were not exceeded for insectivorous amphibians using the T-HERPS model at the highest rate of application. LOC is exceeded for non-target terrestri al plants and thereby critical habitat could be affected as a result of these potential impacts. 1 No effect (NE); May affect, but not likely to adversely affect (NLAA) ; May affect, likely to adversely affect (LAA)
Table 1-2 Effects Determination Summary for Pendimethalin Use and CRLF Critical Habitat Impact Analysis Assessment

Endpoint Effects Determination Basis for Determination

Modification of aquatic-phase PCE

Habitat effects Effects to riparian vegetation (terrestrial plants) and aquatic non-vascular and vascular plants result in LOC exceedances. These effects may indirectly affect the CRLF via reduction in food supply, changes in available cover, physical parameters of the waterbody (e.g. increase temperature or turbidity) LOC is exceeded for effects to non-vascular aquatic plants, freshwater invertebrates (chronic and acute effects) and fish or frogs (chronic and acute effects).

1 3Modification of terrestrial-phase PCE Effects to riparian vegetation (terrestri al plants) result in LOC exceedances. Effects may result in changes in community composition or relative abundance of riparian plant species, possibly altering terrestrial – phase CRLF habitat. Chronic LOC is exceeded for mammal. Although there are NLAA determinations for other prey items, small mammals constitute up to half of the food intake for CRLF and reduction in small mammalian populations may be significant.
Based on the conclusions of this assessment, a formal consultation with the U. S. Fish and Wildlife Service under Secti on 7 of the Endangered Species Act should be initiated.
When evaluating the significance of this ri sk assessment’s direct /indirect and adverse habitat effects determinations, it is important to note that pesticide exposures and predicted risks to the species and its resources (i.e., food and habitat) are not expected to be uniform across the action area. In fact, given the assumptions of drift and downstream transport (i.e., attenuation with distance), pe sticide exposure and associated risks to the species and its resources are expected to d ecrease with increasing di stance away from the treated field or site of application. Eval uation of the implication of this non-uniform distribution of risk to the species would require information and assessment techniques that are not currently available. Examples of such information and methodology required for this type of analysis would include the following:

• Enhanced information on the density and distribution of CRLF life stages within specific recovery units and/or designated critical habitat within the action area. This information would allow for quantitative extrapolation of the present risk assessment’s pred ictions of individual effects to the proportion of the population extant with in geographical areas where those effects are predicted. Furthermore, such population information would allow for a more comprehensive eval uation of the significance of potential resource impairment to individuals of the species.

• Quantitative information on prey base requirements for individual aquaticand terrestrial-phase frogs. Wh ile existing information provides a preliminary picture of the types of food sources util ized by the frog, it does not establish minimal requirements to sustain healthy individuals at varying life stages. Such information could be used to establish biologically relevant thresholds of ef fects on the prey base, and ultimately establish geographical limits to those effects. This information could be used together with the density data discussed above to characterize the likelihood of adverse effects to individuals.

• Information on population responses of prey base organisms to the pesticide. Currently, methodologies are limited to predicting exposures and likely levels of direct mortality, growth or reproductive impairment immediately following exposure to the pesticide. The degree to which repeated exposure events and the inherent demographic characteristics of the prey population play into the ex tent to which prey resources may recover is not predictable. An e nhanced understanding of long-term prey responses to pesticide exposure would allow for a more refined

1 4determination of the magnitude and duration of resource impairment, and together with the information descri bed above, a more complete prediction of effects to individual frogs and potential modificati on to critical habitat.



### 2.0 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 life history st ages, habitat components, chemical properties, exposure routes, and endpoints. The structure of th is risk assessment is based on guidance contained in U.S. EPA’s Guidance for Ecol ogical Risk Assessment (U.S. EPA 1998), the Services’ Endangered Species Consul tation Handbook (USFWS/NMFS 1998) and is consistent with procedures and methodology outlined in the Overview Document (U.S. EPA 2004) and reviewed by the U.S. Fish and Wildlife Service and National Marine Fisheries Service (USFWS/NMFS 2004).

2.1 Purpose The purpose of this endangered species assessme nt is to evaluate potential direct and indirect effects on individuals of the fede rally threatened California red-legged frog (Rana aurora draytonii) (CRLF) arising from FIFRA regulatory acti ons regarding use of pendimethalin on alfalfa, lupine for s eed, almond, beech nut, brazil nut, butternut, cashew, chestnut, chinquapin, filbert (hazel nut), hickory nut, macadamia nut (bushnut), mayhaw (hawthorn), pecan, pistachio, wa lnut (English/black), calamondin, citron (citrus), citrus, citrus hybrids other thantangelo, grapefruit, kumquat, lemon, lime, orange, pummelo (shaddock), tangelo, tangerines, Brassica (head and stem) vegetables, broccoli, broccoli (Chinese), brussels sprouts, cabbage, cabbage (Chinese), cauliflower, kohlrabi, mustard cabbage (gai choy - pak-choi), corn (fie ld, pop, sweet), sunflower, cotton, forest trees (all species), Christmas tree plantations, apple, apricot, cherry, crabapple, fig, loquat, nectarine, peach, pear, pepino (melon pear), plum, plum (Japanese), pomegranate, prune, quince, small fruits, garlic, leek, grapes, eggplant, olive, onion (green, scallions, spring), shallot, potat o (white/Irish), nona gricultural rights-ofway/fencerows/hedgerows, artichoke, asparagus , beans (dry, succulent/lima/snap), carrot (including tops), garbanzos (including chick peas), legume vegetables, lentils, peanuts, peas (dry, early dwarf, pigeon, southern/cowpea), pepper, strawberry, tomato, groundcherry (strawberry tomato, tomatillo), airports/landing fields, commercial/industrial lawns, golf course turf , industrial areas (outdoor), ornamental and/or shade trees, ornamental ground cover, ornamental herbaceous plants, ornamental lawns and turf, ornamental nonflowering plants, ornamental sod farm (turf), ornamental woody shrubs and vines, recreation area lawns, residential lawns, shelterbelt plantings, sorghum, wheat, and rice. In addition, this assessment evaluates whether use on these sites is expected to result in effects to th e species’ designated cri tical habitat. This ecological risk assessment has b een prepared consistent with a settlement agreement in the case Center for Biological Diversity(CBD) vs. EPA et al. (Case No. 02-1580­ JSW(JL)) entered in Federal District Court for the Northern District of California on October 20, 2006.

1 5In this assessment, direct a nd indirect effects to the CRLF and potential effects to its designated critical habitat are evaluated in accordance with the methods described in the Agency’s Overview Document (U.S. EPA 2004). Screening level methods include use of standard models such as PRZM-EXAMS, T-REX, TerrPlant, AgDRIFT, and AGDISP, all of which are described at length in the Overview Document. Additional refinements include an analysis of the us age data, consideration of available monitoring data, a spatial analysis, and use of the T-HERPS model. Use of such information is consistent with the methodology described in the Overview Docume nt (U.S. EPA 2004), which specifies that “the assessment process may, on a case-by- case basis, incorporate additional methods, models, and lines of evidence that EPA finds technically appropriate for risk management objectives” (Section V, page31 of U.S. EPA 2004).
In accordance with the Overview Document, provisions of the ESA, and the Services’ Endangered Species Consultation Handbook, the a ssessment of effects associated with registrations of pendimethalin is based on anaction area. The action area is the area directly or indirectly affect ed by the federal action. It is acknowledged that the action area for a national-level FIFRA regulatory decision associated with a use of pendimethalin may potentially involve numerou s areas throughout the United States and its Territories. However, for the purposes of this assessment, attention will be focused on relevant sections of the action area includi ng those geographic areas associated with locations of the CRLF and its designated criticalhabitat within the state of California. As part of the “effects determination,” one of the following three conclusions will be reached regarding the potential use of pendimethalin in accordance withcurrent labels:

• “No effect”;

• “May affect, but not likely to adversely affect”; or

• “May affect and likely to adversely affect”.
Designated critical habitat identifies specific areas that have the phys ical and biological features, (known as primary constituent elements or PCEs) essential to the conservation of the listed species. The PCEs for CRLF are aquatic and upland areas where suitable breeding and non-breeding aquatic habitat is located, interspe rsed with upland foraging and dispersal habitat.

If the results of initial screening-level assessment methods show no direct or indirect effects (no LOC exceedances) upon individual CRLF or upon the PCEs of the species’ designated critical habitat, a “no effect” determination is made for use of pendimethalin as it relates to this species and its designated critical habitat. If, how ever, potential direct or indirect effects to individual CRLF are anti cipated or effects may impact the PCEs of the CRLF’s designated critical habitat, a pre liminary “may affect” determination is made for the FIFRA regulatory acti on regarding pendimethalin.
If a determination is made that use of pendi methalin within the action area(s) associated with the CRLF “may affect” this species or its designated criticalhabitat, additional information is considered to refine the poten tial for exposure and fo r effects to the CRLF

1 6and other taxonomic groups upon which these sp ecies depend (e.g., aquatic and terrestrial vertebrates and invertebrates, aquatic plan ts, riparian vegetation, etc.). Additional information, including spatial analysis (to de termine the geographical proximity of CRLF habitat and pendimethalin use sites) and fu rther evaluation of the potential impact of pendimethalin on the PCEs is also used to determine whether effects to designated critical habitat may occur. Based on the re fined information, the Agency uses the best available information to disti nguish those actions that “may affect, but are not likely to adversely affect” from those actions that “may affect and are likely to adversely affect” the CRLF or affect the PCEs of its designate d critical habitat. This information is presented as part of the Risk Characteri zation in Section 5 of this document.
The Agency believes that the analysis of di rect and indirect eff ects to listed species provides the basis for an analys is of potential effects on the designated critical habitat. Because pendimethalin is expected to direc tly impact living organisms within the action area (defined in Section 2.7), critical habitat analysis fo r pendimethalin is limited in a practical sense to those PCEs of critical habitat that are biological or that can be reasonably linked to biologically mediated processes (i.e., the bi ological resource requirements for the listed species associatedwith the critical habitat or important physical aspects of the habitat that may bereasonably influenced through biological processes). Activities that may modify critical habitat are th ose that alter the PCEs and appreciably diminish the value of the habitat. Evaluation of actions related to use of pendimethalin that may alter the PCEs of the CRLF’s critical habitat form the basis of the critical habitat impact analysis. Actions that may affect the CRLF’s designated critical habitat have been identifie d by the Services and are di scussed further in Section 2.6.

2.2 Scope As described above, the herbicide pendimeth alin has a wide variety of outdoor uses, including both in agri cultural and non-agric ultural settings.
The end result of the EPA pesticide registration process ( i.e. , the FIFRA regulatory action) is an approved product label. The label is a legal document that stipulates how and where a given pesticide may be used. Product labels (also known as end-use labels) describe the formulation type ( e.g. , liquid), acceptable methods of application, approved use sites, and any restricti ons on how applications may be conducted. Thus, the use of pendimethalin in accordance with the approved product labe ls for California is “the action” relevant to this ecological risk assessment.
Although current registrations of pendimethalin allow for use nationwide, this ecological risk assessment and effects determination addresses currently registered uses of pendimethalin in portions of the action area that are reasonably assumed to be biologically relevant to the CRL F and its designated critical habitat. Further discussion of the action area for the CRLF and its critical habitat is provided in Section 2.7.
Degradates were not considere d, as pendimethalin is relatively stable to all degradation processes measured. The half-lives used as mo del inputs reflect this stability and lack of

1 7degradate production. Sixty-nine measur ements of one potential degradate (4­ hydroxypendamthalin) in California waters produced no detections.
The Agency does not routinely include, in its risk assessments, an evaluation of mixtures of active ingredients, either those mixtur es of multiple active ingredients in product formulations or those in the applicator’s tank. In the case of the product formulations of active ingredients (that is, a registeredproduct containing mo re than one active ingredient), each active ingredient is subj ect to an individual risk assessment for regulatory decision regarding the active ingredient on a particular use site. If effects data are available for a formulated product contai ning more than one active ingredient, they may be used qualitatively or quantitatively in accordance with the Agency’s Overview Document and the Services’ Evaluation Memorandum (U.S., EPA 2004; USFWS/NMFS 2004).
Pendimethalin has registered products that c ontain multiple active ingredients. Analysis of the available open literature and acute oral mammalian LD 50data for multiple active ingredient products relative to the single active ingredient is provided in Appendix B. The results of this analysis show that an assessment based on the toxicity of the single active ingredient of pendimethalin is appropriate.

2.3 Previous Assessments A Reregistration Eligibility Decision (RED) ecological risk chapter was completed in 1997. The RED concluded that pendimethalin w ould not represent a high acute risk to birds or a high acute or chroni c risk to mammals. The chronic risk to birds could not be determined because avian reproduction studies had not been submitted. Chronic risk Levels of Concern (LOCs) for fish were exceeded by a small margin. But it was presumed that overall, pendimethalin did not re present a high risk to aquatic animals and plants, including estuarine organisms. The use of pendimethalin may adversely affect endangered species of terrestrial and semi-aquatic plants, aquatic plan ts and invertebrates including mollusks, fish, and birds (specifically grazers). The risk to nontarget terrestrial and semi-aquatic plants was expected to be moderate.
On December 1, 2004, EPA initiated consultati on with the National Marine Fisheries Service (NMFS) requesting concurrence in a determination relative to potential effects from pendimethalin uses to Pacific salmon and steelhead. In th e assessment supporting that consultation, EPA concluded that pendime thalin has moderate to high laboratory toxicity to fish and aquatic invertebrates and somewhat le ss toxicity on aquatic plants. OPP determined that any effects of con cern would be directly on listed salmon and steelhead and would vary for different uses and species. It was further determined that pendimethalin would not affect salmon and steelhead food or cover, nor adversely modify their Critical Habitat from any of the registered uses except a single aerial use - aerial application to corn. OPP's conclusi ons relative to 26 list ed Pacific salmon and steelhead was that uses of pendimethalin were not likely to adversel y affect four species and would have no effect on twenty-two species reviewed. A response to this request is anticipated from NMFS in 2012.

1 82.4 Stressor Source and Distribution

2.4.1 Environmental Fate Assessment
The environmental fate properties of pendimetha lin indicate that it is persistent, with half-lives in relevant compartments of 172 days (soil) and 208 to 330 days (anaerobic and aerobic aquatic systems). Only the aqueous photolysis half-life is relatively short (42 days) but photolysis may not occur because of the strong tendency of pendimethalin to sorb to sediment (log Kow = 5.18, average Koc = 17,040 mL/g O.C.). Pendimethalin may be bioaccumulative in aquatic organisms. A whole-body bioconcentration factor (BCF) of 5100 from a 35-day exposure was measured in bluegill sunfish. BCFs were lower in catfish (about 1600) and negligible in guppy. The most rapid dissipation process for pendimethalin appears to bevolatilization from moist soil (half-life about 12.5 days). Thus, pendimethalin may be transported away from the site of application before it degrades, making atmospheric transport a po tentially important exposure mechanism. However, EPISuite v4.0 ( http://www.epa.gov/oppt/e xposure/pubs/episuite.htm ), an EPA-sponsored environmental fate estimati on program, estimates of atmospheric halflife (4.2 hours due to reacti on with hydroxyl radical, AOPWin program) and sorption to airborne particles (1 to 7% , AEROWin program) indicate th at long-range transport may not be a concern. The tendency of pendimethal in to partition to sediment, and its long half-life there, make transport by movement of sediment in flowing water systems a

concern. Table 2.1 lists the environmental fate properties of pendimethalin, along with the major and minor degradates detected in the submitted environmental fate and transport studies.

1 9Table 2-1 Summary of PendimethalinEnvironmental Fate Properties
Study Value (units) Major Degradates Minor Degradates MRID # Study Status

Hydrolysis Stable None 00106777 acceptable

Direct Aqueous Photolysis Dark corrected, continuous irradiation half-life 21 days; 12-hour light/dark half-life 42 days.

16.5-day half-life 37 minor, unidentified degradates 2,6-dinitro-3,4

- dimethylaniline (9.3% of applied) 00153763

43808201 acceptable

Soil Photolysis Stable None 00153764 acceptable

Aerobic Soil Metabolism 172 day (Deviation from IPG, as explained in 1997 RED) Range 42-1322 days 2,6-dinitro3,4-xylidine 4-[(1-ethylpropyl)amino]-2

- methyl-3,5-dinitrobenzyl alcohol 4-[(1-ethylpropyl)amino]-2

- methyl3,5-dinitro-o-toluic acid 40185104 acceptable

Anaerobic Soil Metabolism Stable 98% parent at 60 days 2,6-dinitro3,4-xylidine 4-[(1-ethylpropyl)amino]-2

- methyl-3,5-dinitrobenzyl alcohol 4-[(1-ethylpropyl)amino]-2

- methyl3,5-dinitro-o-toluic acid 40185105 acceptable

Anaerobic Aquatic Metabolism 208-day half-life (upper 90 th%ile confidence bound on mean) None 40813501 43154702 acceptable

Aerobic Aquatic Metabolism 330 days (single value) None 47385201 acceptable

K d-ads / K d-des (mL/g)

K oc- ads / K oc-des (mL/g) 30 – 854 (U.S. soils) 61 – 285 (Japanese soils)

17,040 mL/g O.C. (U.S. soils) (avg of 5 values, 13000 – 29400) 7011- 43863 mL/g o.c. (Japanese soils) n.a. 00153765 43041901 acceptable

Laboratory Volatility Volatilization half-life 12.5 days from moist loam soil None measured 00153766

Fish Bioaccumulation Bioconcentration factor BCF = 5100, 35-day exposure 4-[(1-ethylpropyl)amino]-2

- methyl-3,5-dinitrobenzyl alcohol (3.1%) 00156726 00158235 acceptable

2 0Study Value (units) Major Degradates Minor Degradates MRID # Study Status

Terrestrial Field Dissipation 34-day half-life in California almond orchard, sandy loam soil. No leaching below 6 inches. 41722504 acceptable

Aquatic Field Dissipation No data

2.4.2 Environmental Transport Assessment
Potential transport mechanisms include pesticide surface water runoff, spray drift, and secondary drift of volatilized or soil-bound residues leading to deposition onto nearby or more distant ecosystems. Surface water runoff and spray drift are expected to be the major routes of exposure for pendimethalin.

A number of studies have documented atmospheric transport and re-deposition of pesticides from the Central Valley to the Sierra Nevada Mountains (Fellers et al., 2004, Sparling et al., 2001, LeNoir et al., 1999, and McConnell et al., 1998). Prevailing winds blow across the Central Valley eastward to the Sierra Nevada M ountains, transporting airborne industrial and agricultural pollutants into the Sierra Nevada ecosystems (Fellers et al., 2004, LeNoir et al., 1999, and McConnell et al., 1998). Several se ctions of critical habitat for the CLRF are located east of the Central Valley. The magnitude of transport via secondary drift depends on the pendimethalin’s ability to be mobilized into air and its eventual removal through wet and dry depos ition of gases/particles and photochemical reactions in the atmosphere. Therefore, phys icochemical properties of pendimethalin that describe its potential to enter the air from water or soil ( e.g., Henry’s Law constant and vapor pressure), pesticide use data, modeled estimated concen trations in water and air, and available air monitoring data from the Central Valley and the Sierra Nevadas are considered in evaluating the potential for atmospheric transport of pendimethalin to locations where it could impact the CRLF.
In general, deposition of drifting or volatilizedpesticides is expectedto be greatest close to the site of application. Computer m odels of spray drift (AgDRIFT and/or AGDISP) are used to determine potential exposures to aquatic and terrestrial organisms via spray drift.

2.4.2 Mechanism of Action
Pendimethalin is a selective herbicide regi stered for control of broadleaf weeds and grassy weed species on a variety of ag ricultural crops, turf, and ornamentals. Pendimethalin disrupts the process of mitosis inthe growth of shoots and roots. It acts as a microtubule disruptor by inhibiting cell divi sion and cell elongati on in plants, and is generally applied early in the growing season. Absorption of the herbicide takes place at the roots and the shoots. Very little transloc ation occurs from the site of intake.

2 12.4.3 Use Characterization
Pendimethalin is applied as a liquid spray formulation. Pendimethalin can be applied either by aerial equipment or using ground e quipment to a variety of row crops, orchard crops, vineyards, sod, seed, and to rice. It can be broadcasted by air or ground, and be banded as a directed spray or applied by irri gation equipment in various crops. It can also be left on the soil surface or incorporated.
Approximately 27 million pounds of pendimethalin were applied in 2002 according to the National Center for Food and Agriculture, and the majority was applied to soybeans (39.6%), cotton (20.22 %), and corn (19.4 %) (F ig. 2.1). Together, soybeans, cotton, and corn account for 79 % of the applied pendi methalin nationwide. This existing use information is provided as a basis for cons idering background exposures from existing

use. Table 2.2 presents the uses and corres ponding application rates and methods of application considered inthis assessment.

Table 2-2 Pendimethalin Uses Assessed for the CRLF

Use Max. Single Appl. Rate

(lb ai/A) Max. Number of Application

per Year Application Method

walnut (english/black), tangerines, tangelo, small fruits, pummelo (shaddock), pomegranate , pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin, chestnut, cashew, calamondin, butternut, brazil nut, beech nut, almond, grapes. 6.0 1 ground

Prune, plum, pear, peach, olive, nectarine, fig, cherry, apricot, apple, ornamental and/or shad e trees, nonagricultural rights-ofway, fencerows, hedgerows, mulc h, industrial areas (outdoor), forest trees (all or unspecified), Christmas tree plantations, recreation area lawns, loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa 4.0 1 ground, aerial

Asparagus, artichoke 3.9 1 ground, aerial
golf course turf, airports/landing fields 3.5 1 ground, aerial

residential lawns 3.0 1 ground, aerial
Shallot, onion, corn (sweet, pop, field) 2.0 1 ground, aerial

Carrot 1.9 1 ground, aerial

Sunflower 1.73 1 ground, aerial Tomato, tomatillo, tobacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-typebeans, cotton, cowpea (southern pea, black-eyed bean), 1.485 1 ground, aerial

2 2Use Max. Single Appl. Rate

(lb ai/A) Max. Number of Application

per Year Application Method

Wheat, pepper, pepino (melon pear), groundcherry, eggplant 1.425 1 ground, aerial
Strawberry 1.485 2 ground, aerial
Legume vegetables 1.24 1 ground, aerial Rice, mustard cabbage (gai choy, pak-choi), kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 1 ground, aerial

2 3The figure below summarizes pendimethalin use nationwide in 2002. Pendimethalin is used primarily on soybeans, cotton, corn, sugar cane, peanuts, rice, sunflower, potatoes, tobacco, and onions. Most use is apparently outside of Californi a. Non-agricultural uses, which predominate in California, are not represented on this map. The map was downloaded from a U.S. Geological Survey (USGS), National Water Quality Assessment Program (NAWQA) website.

http://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=02&map=m1629 Figure 2.1 Pendimethalin Use in Total Pounds per County
Analysis of labeled use information is the critical first step in evaluating the federal action. The current label for pendimethalinrepresents the FIFRA regulatory action; therefore, labeled use and app lication rates specified on the label form the basis of this assessment. The assessment of use information is critical to the deve lopment of the action area and selection of appropriatemodeling scenarios and inputs.
The Agency’s Biological and Economic Analysis Division (BEAD) provides an analysis of both national- and county-l evel usage information (Kaul and Jones, 2006) using state2 4level usage data obtained from USDA-NASS 1 , Doane ( www.doane.com ; the full dataset is not provided due to its pr oprietary nature) and the California’s Department of Pesticide Regulation Pesticide Use Re porting (CDPR PUR) database 2. CDPR PUR is considered a more comprehensive source of usage data than USDA-NASS or EPA proprietary databases, and thus the usage data reported for pendimethalin by county in this California-specific assessment were generated using CDPR PUR data. Eight years (1999-2006) of usage data were included in this analysis. Data from CDPR PUR were obtained for every pesticide application madeon every use site at the section level (approximately one square mile) of the public land survey system. BEAD summarized these data to the county level by site, pesticide, and unit treated. Calculating county-level usage involved summarizing across all applications made within a section and then across all sections within a county for each use site and for each pesticide. The county level usage data that were calculated include: average annual pounds applied, average annual area treated, and average and maximum application rate across all five years. The units of area treated are also provided where available.
Some uses reported in the CDPR PUR database may be different than those considered in the assessment. The uses considered in th is risk assessment represent all currently registered uses according to a review of all cu rrent labels. No other uses are relevant to this assessment. Any other reported use, suchas may be seen in the CDPR PUR database, represent either historic uses that have been canceled, mis-reported uses, or mis-use. Historical uses, mis-reported uses, and misuseare not considered part of the federal action and, therefore, are not c onsidered in this assessment.

Table 2.3 below gives the total number of pounds of pendimethalin used in California counties from 1994 to 1998 and 1999 to 2006. Th e figures represen t the sum of the average number of pounds used in each yearof the two periods, as reported in the Pesticide use Reporting database (PUR). Su mmaries of the data were provided by OPP’s Biological and Economic Analysis Division (BE AD). The data indicate that the largest amounts were used in Kings, Fresno, and Kern counties, all of which exceeded 150,000 pounds. Thirteen counties (Santa Barbara th rough Glenn) showed use of between 10,000 and 100,000 pounds during the period. Twenty-two counties (Contra Costa through El Dorado) had usage of between 1,000 and 10,000 pounds. Overall, 54 of 58 California counties had reported usage of pendimethali n, indicating that use of the compound is geographically widespread. This is a strong line of evidence that the CRLF is potentially exposed to pendimethalin.

1 United States Depart of Agriculture (USDA), Natio nal Agricultural Statistics Service (NASS) Chemical Use Reports provide summary pesticide usage statistic s for select agricultural use sites by chemical, crop and state. See http://www.usda.gov/nass/pubs/estindx1.htm#agchem

. 2The California Department of Pesticide Regulation’s Pesticide Use Reporting database provides a census of pesticide applications in the state. See http://www.cdpr.ca.gov/docs/pur/purmain.htm.

2 5Table 2-3 Summary of California Departme nt of Pesticide Registration (CDPR) Pesticide Use Reporting (PUR) Data from 1994 to 2006 for Currently Registered Pendimethalin Uses: By County

County 1994 – 1998 1999- 2006 Total KINGS 99690 95429 195119 FRESNO 74212 77816 152028 KERN 90122 59505 149627 SANTA BARBARA 820 83486 84306 TULARE16738 33549 50287 LOS ANGELES 4671 41639 46310 IMPERIAL 15584 24149 39733 STANISLAUS 9128 24623 33751 RIVERSIDE 15279 14997 30276 MERCED 10480 9747 20227 SAN JOAQUIN 6801 11203 18004 MADERA 7660 10086 17746 BUTTE 5758 5974 11732 SANTA CLARA 5717 5838 11555 GLENN4865 6202 11067 CONTRA COSTA 3222 6083 9305 ORANGE 5272 3634 8906 SACRAMENTO 5571 3030 8601 SAN DIEGO 6588 1854 8442 SOLANO 2211 4261 6472 SONOMA2897 3546 6443 ALAMEDA 1810 3288 5098 YOLO 1322 3640 4962 PLACER 1309 3167 4476 SAN BERNARDINO 2339 2073 4412 MONTEREY2328 2052 4380 COLUSA1149 2985 4134 SAN LUIS OBISPO 1761 1610 3371 SUTTER 1109 1857 2966 TEHAMA1148 1212 2360 YUBA 371 1368 1739 SAN MATEO 798 854 1652 VENTURA 824 809 1633 SAN BENITO 809 753 1562 CALAVERAS 609 665 1274 SHASTA 593 642 1235 EL DORADO 466 611 1077 NAPA 418 411 829 LAKE367 261 628 MARIN 563 46 609 TUOLUMNE 239 361 600 LASSEN 169 309 478 MODOC 84 389 473

2 6MENDOCINO 158 293 451 AMADOR272 145 417 SISKIYOU 138 250 388 NEVADA 307 74 381 SANTA CRUZ 148 131 279 SAN FRANCISCO 85 116 201 MONO 149 39 188 HUMBOLDT53 19 72 INYO 49 11 60 MARIPOSA24 4 28 TRINITY 0 1 1

Table 2.3b below shows the number of pounds of pendimethalin applied by crop and use site, during the periods 1994 to 1998, and 1999 to 2006. The figures are aggregated across counties, and are ranked by total numbers of pounds applied in the entire period. Only crops or use sites with at leas t 1,000 pounds usage are shown in the table.
Cotton is the major use, with nearly two million pounds applied from 1994 to 2006. Six use sites (landscape, almond, rights-of-way, garlic, onions, pistachi o, and alfalfa) each totaled over 100,000 pounds applied. A further 18 uses (nursery through nectarine) each had from 10,000 to 100,000 pounds of usage.
It is notable that non-agric ultural uses (landscape and rights-of-way) are among the highest uses of pendimethalin. Based on the county rankings, it is concluded that these uses represent the greatest part of the usage in urban counties.

Table 2.3b. Summary of California Departme nt of Pesticide Registration (CDPR) Pesticide Use Reporting (PUR) Data from 1994 to 2006 for Currently Registered Pendimethalin Uses: By Crop/Use Site

CROP/USE SITE 1994-1998 lbs 1999-2006 lbs TOTAL lbs COTTON1198354 787909 1986263 LANDSCAPE MAINTENANCE 213421 224903 438324 ALMOND 124150 88858 213008 RIGHTS OF WAY 40510 146505 187015 GARLIC 100657 70532 171189 ONION, DRY & GREEN 49023 93909 142932 PISTACHIO 28480 93363 121843 ALFALFA3327 99865 103192 NURSERY - ALL 43897 44167 88064 GRAPE, WINE 39711 45880 85591 POTATO 41086 35707 76793 GRAPE 34005 25160 59165 CORN, HUMAN CONSUMPTION 29757 28782 58539 BEAN, DRIED 14529 38200 52729 UNCULTIVATED AG / nonag 8370 42817 51187 WALNUT 17340 29352 46692

2 7CORN (FORAGE - FODDER) 13629 22894 36523 SUNFLOWER8257 12354 20611 ORANGE2317 17988 20305 PEACH 3572 13534 17106 RICE1237 15149 16386 BEAN, UNSPECIFIED 11229 4922 16151 SOIL FUMIGATION/PREPLANT 6852 8718 15570 PRUNE 12351 3213 15564 BEAN, SUCCULENT 2817 7853 10670 NECTARINE 2529 8053 10582 WHEAT 7703 1143 8846 PLUM 594 6954 7548 CHERRY 0 6913 6913 SAFFLOWER 180 3853 4033 STRUCTURAL PEST CONTROL 2204 1685 3889 TOMATO 796 2863 3659 CELERY 3354 15 3369 LEMON 817 2288 3105 APPLE 2369 594 2963 TURF/SOD 1624 1013 2637 WATER(INDUSTRIAL) 0 1429 1429 SUGARCANE72 1307 1379 TANGERINE174 1178 1352 SORGHUM/MILO 892 281 1173

2.5 Assessed Species The CRLF was federally listed as a threaten ed species by USFWS effective June 24, 1996 (USFWS 1996). It is one of two subspecies of the red-legged frog and is the largest native frog in the western United States (U SFWS 2002). A brief summary of information regarding CRLF distribution, repr oduction, diet, and habitat re quirements is provided in Sections 2.5.1 through 2.5.4, respectively. Further information on the status, distribution, and life history of and specific threats to the CRLF is provided in Attachment 1.

Final critical habitat for the CRLF was designated by USFWS on April 13, 2006 (USFWS 2006; 71 FR 19244-19346). Further information on designated critical habitat for the CRLF is provided in Section 2.6.

2.5.1 Distribution
The CRLF is endemic to California and Baja California (Mexico) and historically inhabited 46 counties in Ca lifornia including the Central Valley and both coastal and interior mountain ranges (USFWS 1996). Its range has b een reduced by about 70%, and the species currently resides in 22 counties in California (USFWS 1996). The species has an elevational range of near sea level to 1,500 meters ( 5,200 feet) (Jennings and Hayes 1994); however, nearly all of the known CRLF populations have been documented below 1,050 meters (3,500 feet) (USFWS 2002).

2 8Populations currently exist along the northern California coast, northern Transverse Ranges (USFWS 2002), foothills of the Sierra Ne vada (5-6 populations), and in southern California south of Santa Barbara (two populations) (Fellers 2005a). Relatively larger numbers of CRLFs are located between Mari n and Santa Barbara Counties (Jennings and Hayes 1994). A total of 243 streams or draina ges are believed to be currently occupied by the species, with the greatest numbers in Monterey, San Luis Obispo, and Santa Barbara counties (USFWS 1996). Occupied drai nages or watersheds include all bodies of water that support CRLFs (i.e., streams, creeks, tributaries, associated natural and artificial ponds, and adjacent drainages), and habitats through which CRLFs can move (i.e., riparian vegetation, uplands) (USFWS 2002).

The distribution of CRLFs with in California is addressed inthis assessment using four categories of location including r ecovery units, core areas, desi gnated critical habitat, and known occurrences of the CRLF reported in the California Natural Diversity Database (CNDDB) that are not included within core ar eas and/or designated critical habitat (see Figure 2.2). Recovery units, core areas, and other known occurrences of the CRLF from the CNDDB are described in further detail in Attachment I, and desi gnated critical habitat is addressed in Section 2.6. Recovery units are large areas defined at the watershed level that have similar conservation needs and mana gement strategies. The recovery unit is primarily an administrative designation, and land area within the recovery unit boundary is not exclusively CRLF habitat. Core areas are smaller areas within the recovery units that comprise portions of the species’ hi storic and current range and have been determined by USFWS to be important in th e preservation of the species. Designated critical habitat is generally contained within the core areas, although a number of critical habitat units are outside the boundaries of core areas, but within the bound aries of the recovery units. Additional information on CRLF occurrences from the CNDDB is used to cover the current range of the species not included in core areas and/or designated critical habitat, but within the recovery units.

Other Known Occurrences from the CNDBB
The CNDDB provides location and natural history information on species found in California. The CNDDB serves as a repositor y for historical and cu rrent species location sightings. Information regarding known occurrences of CRLFs outside of the currently occupied core areas and designated critical habitat is considered in defining the current range of the CRLF. See: http://www.dfg.ca.gov/bdb/html/cnddb_info.html for additional information on the CNDDB.

2 9and Western

o Bay

es and Tehachapi
nsular Ranges Recovery Units 1

. Sierra Nevada Foothills and C entral Valley 2

. North Coast Range Foothills Sacramento River Valley 3

. North Coast and North San Fr ancisco Bayancisco Bay 4

. South and East San Francisc 5

. Central Coast 6

. Diablo Range and Salinas Valley 7

. Northern Transverse Rang Mountains 8

. Southern Transverse and Peni

Core Ar eas 1. Feather River 2. Yuba River- S. Fork Feather River 2. Yuba River- S. Fork Feather River 3. Traverse Creek/ Middle Fork/ American R. Rubicon 3. Traverse Creek/ Middle Fork/ American R. Rubicon 4. Cosumnes River 4. Cosumnes River 5. South Fork Calaveras River* 5. South Fork Calaveras River* 6. Tuolumne River* 7. Piney Creek* 8. Cottonwood Creek 9. Putah Creek – Cache Creek* 9. Putah Creek – Cache Creek* 10. Lake Berryessa Tributaries 10. Lake Berryessa Tributaries 11. Upper Sonoma Creek 11. Upper Sonoma Creek 12. Petaluma Creek – Sonoma Creek 12. Petaluma Creek – Sonoma Creek 13. Pt. Reyes Peninsula 13. Pt. Reyes Peninsula 14. Belvedere Lagoon 15. Jameson Canyon – Lower Napa River 15. Jameson Canyon – Lower Napa River 16. East San Francisco Bay 16. East San Francisco Bay 17. Santa Clara Valley 18. South San Francisco Bay 18. South San Francisco Bay 19. Watsonville Slough-Elkhorn Slough 19. Watsonville Slough-Elkhorn Slough 20. Carmel River – Santa Lucia 20. Carmel River – Santa Lucia 21. Gablan Range 21. Gablan Range 22. Estero Bay 22. Estero Bay 23. Arroyo Grange River 23. Arroyo Grange River 24. Santa Maria River – Santa Ynez River 24. Santa Maria River – Santa Ynez River 25. Sisquoc River 25. Sisquoc River 26. Ventura River – Santa Clara River 26. Ventura River – Santa Clara River 27. Santa Monica Bay – Venura Coastal Streams 27. Santa Monica Bay – Venura Coastal Streams 28. Estrella River 28. Estrella River 29. San Gabriel Mountain* 29. San Gabriel Mountain* 30. Forks of the Mojave* 30. Forks of the Mojave* 31. Santa Ana Mountain* 31. Santa Ana Mountain* 32. Santa Rosa Plateau 32. Santa Rosa Plateau 33. San Luis Ray* 33. San Luis Ray* 34. Sweetwater* 34. Sweetwater* 35. Laguna Mountain* 35. Laguna Mountain*

* Core areas that were historically occupied by the California red-legged frog are not included in the map * Core areas that were historically occupied by the California red-legged frog are not included in the map Figure 2.2 Recovery Unit, Core Area, Critic al Habitat, and Occu rrence Designations for CRLF

302.5.2 Reproduction CRLFs breed primarily in ponds; however, theymay also breed in quiescent streams, marshes, and lagoons (Fellers 2005a). Accord ing to the Recovery Plan (USFWS 2002), CRLFs breed from November through late April. Peaks in spawning activity vary geographically; Fellers (2005b) reports peak spawning as early as January in parts of coastal central California. Eggs are fertili zed as they are being laid. Egg masses are typically attached to emergent vegetation, such as bulrushes ( Scirpus spp.) and cattails ( Typha spp.) or roots and twigs, and float on or near the surface of the water (Hayes and Miyamoto 1984). Egg masses contain appr oximately 2000 to 6000 eggs ranging in size between 2 and 2.8 mm (Jennings and Hayes 1994). Embryos hatch 10 to 14 days after fertilization (Fellers 2005a) depending on water temperature. Egg predation is reported to be infrequent and most mortality is associated with the larval stage (particularly through predation by fish); however, predation on eggs by newts has also been reported (Rathburn 1998). Tadpoles re quire 11 to 28 weeks to me tamorphose into juveniles (terrestrial-phase), typically between May and September (Jennings and Hayes 1994, USFWS 2002); tadpoles have been observed to over-winter (delay metamorphosis until the following year) (Fellers 2005b, USFWS 200 2). Males reach sexual maturity at 2 years, and females reach sexual maturity at 3 years of age; adults have been reported to live 8 to 10 years (USFWS 2002). Figure 2.3 depicts CRLF annual reproductive timing.

J F M A M J J A S O N D Light Blue = Breeding/Egg Masses Green = Tadpoles (except those that over-winter) Orange = Young Juveniles Adults and juveniles can be present all year Figure 2.3 CRLF Reproductive Events by Month

2.5.3 Diet Although the diet of CRLF aquatic-phase la rvae (tadpoles) has not been studied specifically, it is assumed that their diet is si milar to that of other frog species, with the aquatic phase feeding exclusiv ely in water and consuming diatoms, algae, and detritus (USFWS 2002). Tadpoles filter and entrap suspended algae (Seale and Beckvar, 1980) via mouthparts designed for effectiv e grazing of periphyton (Wassersug, 1984, Kupferberg et al. ; 1994; Kupferberg, 1997; A ltig and McDiarmid, 1999).
Juvenile and adult CRLFs forage in aquatic a nd terrestrial habitats, and their diet differs greatly from that of larvae. The main food source for juvenile aquatic- and terrestrialphase CRLFs is thought to be aquatic and terrestrial invert ebrates found along the shoreline and on the water surface. Hayes and Tennant (1985) report, based on a study examining the gut content of 35 juvenile and adult CRLFs, that the species feeds on as many as 42 different invertebrate taxa , including Arachnida, Amphipoda, Isopoda, Insecta, and Mollusca. The most commonly obs erved prey species were larval alderflies

3 1( Sialis cf. californica ), pillbugs ( Armadilliadrium vulgare ), and water striders ( Gerris sp). The preferred prey species, however, was the sowbug (Hayes and Tennant, 1985). This study suggests that CRLFs forage primarily above water, although the authors note other data reporting that adults also feed under water, are cannibalistic, and consume fish. For larger CRLFs, over 50% of the prey mass may c onsists of vertebrates such as mice, frogs, and fish, although aquatic and terrestrial inve rtebrates were the most numerous food items (Hayes and Tennant 1985). For adults, feeding activity takes place primarily at night; for juveniles feeding o ccurs during the day and at ni ght (Hayes and Tennant 1985).

2.5.4 Habitat CRLFs require aquatic habitat for breeding, but also use other habitat types including riparian and upland areas throughout their lif e cycle. CRLF use of their environment varies; they may complete their entire life cycl e in a particular habitat or they may utilize multiple habitat types. Overall, populations are most likely to exist where multiple breeding areas are embedded within varying habitats used for dispersal (USFWS 2002). Generally, CRLFs utilize habitat with perennial or near-perennial water (Jennings et al. 1997). Dense vegetation close to water, shadin g, and water of moderate depth are habitat features that appear especially important for CRLF (Hayes and Jennings 1988). Breeding sites include streams, deep pools, b ackwaters within streams and creeks, ponds, marshes, sag ponds (land depressions between fault zones that have filled with water), dune ponds, and lagoons. Breeding adults have be en found near deep (0.7 m) still or slow moving water surrounded by dense vegetati on (USFWS 2002); however, the largest number of tadpoles have been found in sha llower pools (0.26 – 0.5 m) (Reis, 1999). Data indicate that CRLFs do not fre quently inhabit vernal pools, as conditions in these habitats generally are not suitable (Hayes and Jennings 1988).
CRLFs also frequently breed in artificial impoundments such as stock ponds, although additional research is needed to identify habitat requirements within artificial ponds (USFWS 2002). Adult CRLFs use dense, sh rubby, or emergent vegetation closely associated with deep-water pools bordered w ith cattails and dense stands of overhanging vegetation ( http://www.fws.gov/endangered/f eatures/rl_frog/rlfrog.html#where ).
In general, dispersal and habitat use depends on climatic conditions, habitat suitability, and life stage. Adults rely on riparian vegetation for resti ng, feeding, and dispersal. The foraging quality of the riparian habitat depends on moisture, composition of the plant community, and presence of pools and backwater aquatic areas for breeding. CRLFs can be found living within streams at distances up to 3 km (2 miles) from their breeding site and have been found up to 30 m (100 feet) from water in dense riparian vegetation for up to 77 days (USFWS 2002).
During dry periods, the CRLF is rarely found far from water, although it will sometimes disperse from its breeding hab itat to forage and seek other suitable habitat under downed trees or logs, industrial debris, and agricultural features (UWFWS 2002). According to Jennings and Hayes (1994), CRLFs also use sm all mammal burrows and moist leaf litter as habitat. In addition, CRLFs may also use larg e cracks in the bottom of dried ponds as

3 2refugia; these cracks may provide moisture for individuals avoidi ng predation and solar exposure (Alvarez 2000).

2.6 Designated Critical Habitat In a final rule published on April 13, 2006, 34 se parate units of critical habitat were designated for the CRLF by USFWS (USFWS 2006; FR 51 19244-19346). A summary of the 34 critical habitat units relative to USFWS-designated recovery units and core areas (previously discussed in Section 2.5.1) is provided in Attachment I.

‘Critical habitat’ is defined in the ESA as th e geographic area occupi ed by the species at the time of the listing where the physical and biological features necessary for the conservation of the species exis t, and there is a need for special management to protect the listed species. It may also include ar eas outside the occupied area at the time of listing if such areas are ‘essential to the c onservation of the species.’ All designated critical habitat for the CRLF was occupied at the time of listing. Critical habitat receives protection under Section 7 of the ESA (Section 7) through prohibition against destruction or adverse modification with regard to actions carried ou t, funded, or authorized by a federal Agency. Section 7 requires consultation on federal actions that are likely to result in the destruction or adverse modification of critical habitat.

To be included in a critical habitat desi gnation, the habitat must be ‘essential to the conservation of the species.’ Critical hab itat designations identify, to the extent known using the best scientific and commercial data available, habitat areas that provide essential life cycle needs of the species or areas that contai n certain primary constituent elements (PCEs) (as defined in 50 CFR 414.12(b )). PCEs include, but are not limited to, space for individual and population growth and for normal behavior; food, water, air, light, minerals, or other nutritional or physiolo gical requirements; cove r or shelter; sites for breeding, reproduction, rearing (or developmen t) of offspring; and habitats that are protected from disturbance or are represen tative of the histor ic geographical and ecological distributions of a species. The de signated critical habitat areas for the CRLF are considered to have the following PCEs that justify critical habitat designation:

• Breeding aquatic habitat;

• Non-breeding aquatic habitat;

• Upland habitat; and

• Dispersal habitat.
Further description of thes e habitat types is provided in Attachment I.
Occupied habitat may be include d in the critical habitat only if essential features within the habitat may require special management or protection. Theref ore, USFWS does not include areas where existing management is su fficient to conserve the species. Critical habitat is designated outside the geographic area presently occupied by the species only when a designation limited to its present range would be inadequate to ensure the conservation of the species. For the CRLF, all designated critical habi tat units contain all

3 3four of the PCEs, and were occupied by th e CRLF at the time of FR listing notice in April 2006. The FR notice designating critic al habitat for the CRLF includes a special rule exempting routine ranchi ng activities associated withlivestock ranching from incidental take prohibitions. The purpose of this exemption is to promote the conservation of rangelands, which could be bene ficial to the CRLF, and to reduce the rate of conversion to other land uses that are incompatible withCRLF conservation. Please see Attachment I for a full explanation on this special rule.

USFWS has established adverse modification standards for designate d critical habitat (USFWS 2006). Activities that may destroy or adversely modify critic al habitat are those that alter the PCEs and jeopardize the continue d existence of the species. Evaluation of actions related to use of pendimethalin that may alter the PCEs of the CRLF’s critical habitat form the basis of the critical hab itat impact analysis. According to USFWS (2006), activities that may affect critical habitat and therefore result in adverse effects to the CRLF include, but are not limited to the following:
(1) Significant alteration of water chemistry or temperature to levels beyond the tolerances of the CRLF that result in di rect or cumulative adverse effects to individuals and their life-cycles. (2) Alteration of chemical characteristics n ecessary for normal growth and viability of juvenile and adult CRLFs. (3) Significant increase in sediment deposition within the stream channel or pond or disturbance of upland fora ging and dispersal habitat that could result in elimination or reduction of habitat necessary for the growth and reproduction of the CRLF by increasing the sediment deposition to levels that would adversely affect their ability to co mplete their life cycles. (4) Significant alteration of ch annel/pond morphology or geometry that may lead to changes to the hydrologic functioning of the stream or pond and alter the timing, duration, water flows, and levels thatwould degrade or eliminate the CRLF and/or its habitat. Such an effect coul d also lead to increased sedimentation and degradation in water quality to levels that are beyond the CRLF’s tolerances. (5) Elimination of upland foraging and/or aes tivating habitat or dispersal habitat. (6) Introduction, spread, or augmentation of non-native aquatic species in stream segments or ponds used by the CRLF. (7) Alteration or elimination of the CRLF ’s food sources or prey base (als o evaluated as indirect effects to the CRLF)

. As previously noted in Section 2.1, the Agency believes that the analysis of direct and indirect effects to listed species provides the basis for an analysis of potential effects on the designated critical habitat. Because pendi methalin is expected to directly impact living organisms within the action area, critical habitat analysis for pendimethalin is limited in a practical sense to those PCEs of critical habitat that are biological or that can be reasonably linked to biol ogically mediated processes.

3 42.7 Action Area For listed species assessment purposes, the action area is considered to be the area affected directly or indirec tly by the federal action and not merely the immediate area involved in the action (50 CFR 402.02). It is recognized th at the overall action area for the national registration of pendi methalin is likely to encompass considerable portions of the United States based on the large array of agricultural and its non-agricultural uses. However, the scope of this assessment limits consideration of the overall action area to those portions that may be applicable to th e protection of the CRLF and its designated critical habitat within the state of Californ ia. The Agency’s approach to defining the action area under the provisions of the Overview Document (USEPA2004) considers the results of the risk assessment process to es tablish boundaries for that action area with the understanding that exposures below the Agen cy’s defined Levels of Concern (LOCs) constitute a no-effect threshold. For the purposes of this assessment, attention will be focused on the footprint of the action (i.e., th e area where pesticide application occurs), plus all areas where offsite transport (i.e., spray drift, downstream dilution, etc.) may result in potential exposure within the st ate of California that exceeds the Agency’s LOCs.
Deriving the geographical extent of this portion of the action area is based on consideration of the types of effects that pendimethalin may be expected to have on the environment, the exposure levels to pendimetha lin that are associated with those effects, and the best available information concerning the use of pendimethalin and its fate and transport within the state of California. Speci fic measures of ecological effect that define the action area include any direct and indirect toxic effect and any potential modification of its critical habitat, includi ng reduction in survival, growth, and fecundity as well as the full suite of sublethal effects available in the effects literature. Th erefore, the action area extends to a point where environmental expos ures are below any measured lethal or sublethal effect threshold for any biological entity at the whole organism, organ, tissue, and cellular level of or ganization. In situations where itis not possible to determine the threshold for an observed effect, the action ar ea is not spatially limite d and is assumed to be the entire state of California.

The definition of action area requires a stepwise approachthat begins with an understanding of the federal action. The federal action is de fined by the currently labeled uses for pendimethalin. An analysis of labeled uses and review of available product labels was completed. Several of the current labels are special local needs (SLN) labels for other states and some uses on other labels are restricted to specific states other than California and are, therefore, excluded from this assessment. The agricultural and nonagricultural uses that are c onsidered as part of the fede ral action evaluated in this assessment can be found in Table 2.2.
Following a determination of the assessed uses , an evaluation of the potential “footprint” of pendimethalin use patterns (i.e., the area where pestic ide application occurs) is determined. This “footprint” represents the initial area of concern, based on an analysis of available land cover data for the state of California. The initial area of concern is defined as all land cover types and the stream reaches within the land cover areas that

3 5represent the labeled uses described above. A map repr esenting all the land cover types that make up the initial area of concern for pendimethalin is presented in

Figure 2.4.
More information regarding which specific us es are represented for each land cover types can be found in Appendix D.

3 6Figure 2.4. Initial area of concern, or“footprint” of potential use, for Pendimethalin

37Once the initial area of concern is defined, the next step is to define the potential boundaries of the action area by determining the ex tent of offsite tran sport via spray drift and runoff where exposure of one or more taxonomic groups to the pe sticide exceeds the listed species LOCs.
As previously discussed, the action area is defined by the most sensitive measure of direct and indirect ecologicaltoxic effects including re duction in survival, growth, reproduction, and the entire suiteof sublethal effects from valid, peer-reviewed studies.
The action area is determined by the footprint of the action plus all offsite areas where exposure of one or more taxonomic groups to pendimethalin exceeds the Agency’s LOCs. The spatial extent at which the Agen cy’s LOCs are not exceeded is based on the potential exposure level and the most sensitiv e effects endpoints The most sensitive for terrestrial environments was the plant EC25 of 0.01 lb/acre for ryegrass seedling emergence, Table 4.5). The most sensitive e ndpoints for aquatic environments were the duckweed EC50 of 12.5 ppb and the diat om EC50 of 5.2 ppb (section 4.1.3.1).
The routes of exposure that determine the extent of the action area are run-off in stormwater or irrigation water (mostly in the sorbed phase) and spray drift. Volatilization and redeposition (eg., via rainwater) may also c ontribute to the extentof the action area, bur this could not be quantified. A paper by Vogel et al. (2008) found pendimethalin in rainwater in Merced County at a concen tration of 0.143 ppb maximum. This is an additional line of evidence that pendimethalin may be transported by air outside the immediate use site.

The AgDRIFT model (Version 2.01) is used to define how far from the initial area of concern an effect to a given species may be expected via spray drift. The spray drift analysis for pendimethalin using the mo st sensitive endpoint (ryegrass seedling emergence EC25 of 0.01 lb/acre) suggests th at effects are exp ected beyond 1,000 feet from the edge of pendimethalin treated areas
In addition to the buffered area from the spray drift analysis, the final action area also considers the downstream extent of pendimethalin that exceeds the LOC. Based on this analysis, the action area incl udes streams as far as 272 kilometers downstream from forestry use areas.
An evaluation of usage information was c onducted to determine the area where use of pendimethalin may impact the CRLF. This analysis is used to characterize where predicted exposures are most likely to occur, but does not preclude use in other portions of the action area. A more detailed review of the county-level use information was also completed. These data suggest that pendimethal in is widely used both in agricultural and non-agricultural settings in 54 of 58 California counties. Thus, it is likely that pendimethalin use sites and CRLF habitat areas intersect.

3 8Based on these considerations, the action area is considered to be the entire state of California.

2.8 Assessment Endpoints and Measures of Ecological Effect Assessment endpoints are defined as “explicit expressions of the ac tual environmental value that is to be protected.” 3 Selection of the assessment endpoints is based on valued entities (e.g., CRLF, organisms im portant in the life cycle of the CRLF, and the PCEs of its designated critical habitat), the ecosystems potentially at risk (e.g., waterbodies, riparian vegetation, and upland and dispersal habitats), the migration pathways of pendimethalin (e.g., runoff, spray drift, etc.), and the routes by which ecological receptors are exposed to pendimethalin (e.g., direct contact, etc.).

2.8.1 Assessment Endpoints for the CRLF Assessment endpoints for the CRLF include direct toxic effects on the survival, reproduction, and growth of the CRLF, as well as indirect effects, such as reduction of the prey base or modification of its habitat. In addition, potential modification of critical habitat is assessed by evaluating potential eff ects to PCEs, which are components of the habitat areas that provide essential life cycle needs of the CRLF. Each assessment endpoint requires one or more “measures of ecological effect,” defined as changes in the attributes of an assessment endpoint or changes in a surrogate entity or attribute in response to exposure to a pesticide. Specific measures of ecological effect are generally evaluated based on acute and chronic toxicity information from registrant-submitted guideline tests that are performed on a limited number of organisms. Additional ecological effects data from the open literature are also considered. It should be noted that assessment endpoints are limited to direct and indirect effects associated with survival, growth, and fecundity, and do not incl ude the full suite of sublethal effects used to define the action area. According th e Overview Document (USEPA 2004), the Agency relies on acute and chronic effects endpoi nts that are either direct measures of impairment of survival, growth, or fec undity or endpoints for which there is a scientifically robust, peer reviewed relationship that ca n quantify the impact of the measured effect endpoint on the assessment endpoi nts of survival, growth, and fecundity.
A complete discussion of all the toxicity dataavailable for this risk assessment, including resulting measures of ecological effect selected for each taxonomic group of concern, is included in Section 4.0 of this document. A summary of the assessment endpoints and measures of ecological effect selected to characterize po tential assessed direct and indirect CRLF risks associated with exposure to pendimethalin is provided in table 2-4 below.

3 U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.

3 9Table 2-4 Assessment Endpoints and Measures of Ecological Effects Assessment Endpoint Measures of Ecological Effects 4 Aquatic-Phase CRLF (Eggs, larvae, juveniles, and adults) a Direct Effects

1. Survival, growth, and reproduction of CRLF 1a. Most sensitive fish acute LC 50(guideline or ECOTOX) if no suitabl e amphibian data are available 1b. Most sensitive fish chronic NOAEC (guideline or ECOTOX) if no suitable amphibian data are available Indirect Effects and Critical Habitat Effects 2. Survival, growth, and reproduction of CRLF individuals via indirect effects on aquatic prey food supply ( i.e., fish, freshwater invertebrates, nonvascular plants) 2a. Most sensitive fish, aquatic invertebrate, and aquatic plant EC 50 or LC 50 (guideline or ECOTOX) 2b. Most sensitive aquatic invertebrate and fish chronic NOAEC (guideline or ECOTOX) 3. Survival, growth, and reproduction of CRLF individuals via indirect effects on habitat, cover, food supply, and/or primary productivity ( i.e., aquatic plant community) 3a. Vascular plant acute EC 50 (duckweed guideline test or ECOTOX vascular plant) 3b. Non-vascular plant acute EC 50 (freshwater algae or diatom, or ECOTOX non-vascular)

4. Survival, growth, and reproduction of CRLF individuals via effects to riparian vegetation 4a. Distribution of EC 25 values for monocots (seedling emergence, vegetative vigor, or ECOTOX) 4b. Distribution of EC 25 values for dicots (seedling emergence, vegetative vigor, or ECOTOX) Terrestrial-Phase CRLF

(Juveniles and adults) Direct Effects

5. Survival, growth, and reproduction of CRLF individuals via direct effects on terrestrial phase adults and juveniles 5a. Most sensitive birdbor terrestrial-phase amphibian acute LC 50or LD 50 (guideline or ECOTOX) 5b. Most sensitive bird bor terrestrial-phase amphibian chronic NOAEC (guideline or ECOTOX) Indirect Effects and Critical Habitat Effects 6. Survival, growth, and reproduction of CRLF individuals via effects on terrestrial prey ( i.e., terrestrial invertebrates, small mammals , and frogs) 6a. Most sensitive terrestrial invertebrate and vertebrate acute EC 50 or LC 50 (guideline or ECOTOX) c 6b. Most sensitive terrest rial invertebrate and vertebrate chronic NOAEC (guideline or ECOTOX) 7. Survival, growth, and reproduction of CRLF individuals via indirect effects on habitat ( i.e., riparian and upland vegetation) 7a. Distribution of EC 25 for monocots (seedling emergence, vegetative vigor, or ECOTOX 7b. Distribution of EC 25 for dicots (seedling emergence, vegetative vigor, or ECOTOX)

aAdult frogs are no longer in the “aquatic phase” of the amphibian life cycle; however, submerged adul t frogs are considered “aquatic” for the purposes of th is assessment because exposure pathways in the wate r are considerably different that exposure pathways on land

. bBirds are used as surrogates for terrestrial phase amphibians

.

4All registrant-submitted and open literature toxicity data reviewed for this assessment are included in Appendix A.

4 02.8.2 Assessment Endpoints for Desi gnated Critical Habitat As previously discussed, designated critical habitat is assessed to evaluate actions related to the use of pendimethalin that may alter the PCEs of the CRLF’s critical habitat. PCEs for the CRLF were previously described in Section 2.6. Actions that may modify critical habitat are those that alter the PCEs and jeopa rdize the continued existence of the CRLF. Therefore, these actions are id entified as assessment endpoints. It should be noted that evaluation of PCEs as assessment endpoints is limited to those of a biological nature (i.e., the biological resource requirements for the listed species associated with the critical habitat) and those for which pendimethalineffects data are available. Adverse modification to the critical habitat of the CRLF includes, but is not limited to, those listed in Section 2.6.
Measures of such possible effects by labeled use of pendimethalin on critical habitat of the CRLF are described in Table 2-55. Some components of these PCEs are associated with physical abiotic features (e.g., presence and/or depth of a water body, or distance between two sites), which are notexpected to be measurably altered by use of pesticides. Assessment endpoints used for the analysis of designated critical habitat are based on the adverse modification standard established by USFWS (2006).

4 1Table 2-5 Summary of Assessment Endpoints and Measures of Ecological Effect for Primary Constituent Elements of Designated Critical Habitat a
Assessment Endpoint Measures of Ecological Effect Aquatic-Phase CRLF PCEs (Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat) Alteration of channel/pond morphology or geometry a. Most sensitive aquatic plant EC 50(guideline or and/or increase in sediment deposition within the ECOTOX) stream channel or pond: aquatic habitat (including b. Distribution of EC 25 values for terrestrial monocots riparian vegetation) provides for shelter, foraging, (seedling emergence, vegetative vigor, or ECOTOX) predator avoidance, and aquatic dispersal for juvenile c. Distribution of EC 25 values for terrestrial dicots and adult CRLFs. (seedling emergence, vegetative vigor, or ECOTOX)
Alteration in water chemistry/quality including temperature, turbidity, and oxygen content necessary for normal growth and viability of juvenile and adult CRLFs and their food source. a. Most sensitive EC 50 values for aquatic plants (guideline or ECOTOX) b. Distribution of EC 25 values for terrestrial monocots (seedling emergence or vegetative vigor, or ECOTOX) c. Distribution of EC 25 values for terrestrial dicots (seedling emergence, vegetative vigor, or ECOTOX)

Alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source. a. Most sensitive EC 50 or LC 50 values for fish or aquaticphase amphibians and aquatic invertebrates (guideline or ECOTOX) b. Most sensitive NOAEC values for fish or aquatic-phase amphibians and aquatic invertebrates (guideline or ECOTOX)
Reduction and/or modification of aquatic-based food sources for pre-metamorphs ( e.g., algae) a. Most sensitive aquatic plant EC 50(guideline or ECOTOX) Terrestrial-Phase CRLF PCEs (Upland Habitat and Dispersal Habitat) Elimination and/or disturbance of upland habitat; ability of habitat to support food source of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or dripline surrounding aquatic and riparian habitat that are comprised of grasslands, woodlands, and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator avoidance a. Distribution of EC 25 values for monocots (seedling emergence, vegetative vigor, or ECOTOX) b. Distribution of EC 25 values for dicots (seedling Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat within designated emergence, vegetative vigor, or ECOTOX) units and between occupied locations within 0.7 mi of c. Most sensitive food source acute EC 50/LC 50and NOAEC each other that allow for movement between sites values for terrestrial vertebrates (mammals) and including both natural and altered sites which do not invertebrates, birds or terrestrial-phase amphibians, and contain barriers to dispersal freshwater fish. Reduction and/or modification of food sources for terrestrial phase juveniles and adults Alteration of chemical ch aracteristics necessary for normal growth and viability of juvenile and adult CRLFs and their food source.

a Physico-chemical water quality parameters such as salinity, pH , and hardness are not evaluated because these processes are not biologically mediated and, therefore, are not relevant to the endpoints included in this assessment.

422.9 Conceptual Model

2.9.1 Risk Hypotheses Risk hypotheses are specific assumptions abou t potential adverse effects (i.e.,changes in assessment endpoints) and may be based on theory and logic, empirical data, mathematical models, or probability models (U .S. EPA, 1998). For this assessment, the risk is stressor-linked, where the stressor is the release of pendimethalin to the environment. The following risk hypotheses are presumed for this endangered species assessment:
The labeled use of pendimethalin within the action area may:

• directly affect the CRLF by causing mortal ity or by adversely a ffecting growth or fecundity;

• indirectly affect the CRLF by reducing or changing the composition of food supply;

• indirectly affect the CRLF or modify designated critical habitat by reducing or changing the composition of the aquatic plant community in the ponds and streams comprising the species’ current rang e and designated critic al habitat, thus affecting primary productivity and/or cover;

• indirectly affect the CRLF or modify designated critical habitat by reducing or changing the composition of the terrestrial plant community (i.e., riparian habitat) required to maintain acceptable water qual ity and habitat in the ponds and streams comprising the species’ current rangeand designated critical habitat;

• affect the designated critical habitat of the CRLF by reducing or changing breeding and non-breeding aquatic habitat (via modifi cation of water quality parameters, habitat morphology, and/or sedimentation);

• affect the designated critical habitat of the CRLF by reducing the food supply required for normal growth and viabili ty of juvenile and adult CRLFs;

• affect the designated critical habitat of the CRLF by reducing or changing upland habitat within 200 ft of the edge of the riparian vegetation necessary for shelter, foraging, and predator avoidance.

• affect the designated critical habitat of the CRLF by reducing or changing dispersal habitat within designated units and between occupied locations within 0.7 mi of each other that allow for moveme nt between sites including both natural and altered sites which do not contain barriers to dispersal.

• affect the designated critical habi tat of the CRLF by altering chemical characteristics necessary for normal growthand viability of juvenile and adult CRLFs.

2.9.2 Diagram The conceptual model is a graphic representation of the structure of the risk assessment. It specifies the pendimethalinrelease mechanisms, biological receptor types, and effects endpoints of potential concern. The concep tual models for terre strial and aquatic exposures are shown in Figure 2.5 and Figure 2.6, resp ectively, which include the conceptual models for the aquatic and terrestrial PCE components of critical habitat.

4 3Exposure routes shown in dashed lines are not quantitatively considered because the contribution of those potential exposure rout es to potential risks to the CRLF and modification to designated critical habitat is expected to be negligible.

Stressor

Source

Receptors

Attribute Change Pendimethalin applied to use site

Direct application Spray drift and volatilization

Birds/terrestrialphase amphibians/ reptiles/mammals

Terrestrial

insects

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to habitat Terrestrial/riparian plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Mammals/ birds Exposure Media Soil

Ingestion In g estion

Ingestion In g estion Dermal u p take/In g estion Long range atmospheric

transport

Root uptake Wet/dry de p osition

Terrestrial-phase amphibians Ingestion

Figure 2.5 Conceptual Model for Pesticid e Effects on Terrestrial Phase of the CRLF

4 4Stressor

Source

Exposure Media

Uptake/gills Receptors or integument

Fish/aquatic-phase amphibians **Piscivorous mammals

and birds Food chain Reduction in algae Reduction in prey Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to

habitat Aquatic Animals Invertebrates Vertebrates

In g estion In g estion Uptake/gills or integument
A quatic Plants Non-vascular Vascula r Uptake/cell, roots , leaves Pendimethalin applied to use site

Spray drift and volatilization

Surface water/ Sediment Runoff Long range atmospheric

transport

Wet/dry deposition Soil Groundwate r

Riparian plants terrestrial exposure pathways see

Figure 2.5

Attribute Change Individual organisms Reduced survival Reduced growth Reduced reproduction ** Route of exposure includes only inges tion of aquatic fishand invertebrates

Figure 2.6 Conceptual Model for Pesticid e Effects on Aquatic Phase of the CRLF

2.10 Analysis Plan In order to address the risk hypothesis, the potential for direct and indirect effects to the CRLF, its prey, and its habitat is estimat ed. In the following sections, the use, environmental fate, and ecological effects of pendimethalin are characterized and integrated to assess the risks. This is accomplished using a risk quotient (ratio of exposure concentration to effect s concentration) approach. Although risk is often defined as the likelihood and magnitude of adverse ecological effect s, the risk quotient-based approach does not provide a quantitative estim ate of likelihood and/or magnitude of an adverse effect. However, as outlined in the Overview Document (U.S. EPA, 2004), the likelihood of effects to indivi dual organisms from particular uses of pendimethalin is estimated using the probit dose-response slope and either the level of concern (discussed below) or actual calculated risk quotient value.

4 52.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model

2.10.1.1 Measures of Exposure
The environmental fate properties of pendime thalin along with available monitoring data indicate that runoff and spray drift are the principle potential transport mechanisms of pendimethalin to the aquatic and terrestrial habitats of the CRLF. In this assessment, transport of pendimethalin through runoff and spray drift is cons idered in deriving quantitative estimates of pendimethalin exposur e to CRLF, its prey and its habitats.
Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of pendimethalin using maximum labeled application rates and methods of application. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the Exposure Analysis Model System (PRZM/EXAMS). The Tier 1 Rice model is used to estimate pendimethalin concentrations in rice paddy water on the day of application. The m odel used to predict terrestrial EECs on food items is T-REX. Th e model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant . These models are parameterized using relevant reviewed registrant-submitted environmental fate data.
PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are screening simulation models coupled with the input shell pe5.pl (Aug 2007) to generate daily exposures and 1-in-10 year EECs of pendime thalin that may occur in surface water bodies adjacent to application sites receiving pendimethalin through runoff and spray drift. PRZM simulates pesticide applic ation, movement and transformation on an agricultural field and the result ant pesticide loadings to a receiving water body via runoff, erosion and spray drift. EXAMS simulates the fate of the pesticide and resulting concentrations in the water body. The standa rd scenario used fo r ecological pesticide assessments assumes application to a 10-hectar e agricultural field that drains into an adjacent 1-hectare water body, 2-meters deep (20,000 m 3 volume) with no outlet. PRZM/EXAMS was used to estimate screeni ng-level exposure of aquatic organisms to pendimethalin. The measure of exposure for aquatic species is the 1-in-10 year return peak or rolling mean concentration. The 1-in -10 year peak is used for estimating acute exposures of direct effects to the CRLF, as well as indirect effects to the CRLF through effects to potential prey items, including: alg ae, aquatic invertebrate s, fish and frogs. The 1-in-10-year 60-day mean is used for assess ing chronic exposure to the CRLF and fish and frogs serving as prey items; the 1-in-1 0-year 21-day mean is used for assessing chronic exposure for aquatic invertebrates, which are also potential prey items.
Exposure in aquatic environments via bioaccumulation and foodchain exposure was quantified with the KABAM (Kow-based bi oaccumulation) model (documented at http://www.epa.gov/oppefed1/models/w ater/kabam/kabam_user_guide.html).
Exposure estimates for the terrestrial-phaseCRLF and terrestrial invertebrates and mammals (serving as potential prey) assumed to be in the target area or in an area

4 6exposed to spray drift are derived usi ng the T-REX model (version 1.3.1, 12/07/2006). This model incorporates the Kenega nomograph, as modified by Fletcher et al. (1994), which is based on a large set of actual field residue data. The upper limit values from the nomograph represented the 95th percentile of residue values from actual field measurements (Hoerger and Ke nega, 1972). For modeling purposes, direct exposures of the CRLF to pendimethalin through contaminated food are estimated using the EECs for the small bird (20 g) which consumes small insects. Dietary-based and dose-based exposures of potential prey (small mammals) are assessed using the small mammal (15 g) which consumes short grass. The small bird (20g) consuming small insects and the small mammal (15g) consuming short grass are usedbecause these categ ories represent the largest RQs of the size and dietary categorie s in T-REX that are appropriate surrogates for the CRLF and one of its prey items. Es timated exposures of terrestrial insects to pendimethalin are bound by using the dietary based EECs for small insects and large insects.
Birds are currently used as surrogates for te rrestrial-phase CRLF. However, amphibians are poikilotherms (body temperature varies with environmental temperature) while birds are homeotherms (temperature is regulate d, constant, and largely independent of environmental temperatures). Therefore, am phibians tend to have much lower metabolic rates and lower caloric intakerequirements than birds or mammals. As a consequence, birds are likely to consume more food than amphibians on a daily dietary intake basis, assuming similar caloric content of the f ood items. Therefore, the use of avian food intake allometric equation as a surrogate to amphibians is likely to result in an overestimation of exposure and risk for reptiles and terrestrial-phase amphibians. Therefore, T-REX (version 1.3.1) has been refined to th e T-HERPS model (v. 1.0), which allows for an estimation of food intake for poikilotherms using the same basic procedure as T-REX to estimate avian food intake.
EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 1.2.2, 12/26/2006). This model uses es timates of pesticides in runoff and in spray drift to calculate EECs. EECs are ba sed upon solubility and application rate.
Spray drift models, AGDISP and/or AgDRIFT ar e used to assess expos ures of terrestrial phase CRLF and its prey to pendimethalin deposi ted on terrestrial habitats by spray drift. AGDISP (version 8.13; dated 12/14/2004) (Teske and Curbishley, 2003) is used to simulate aerial and ground applications. In addition to the buffered area from the spray drift analysis, the downstream extent of pendimethalin that exceeds the LOC for the effects determination is also considered.
Although volatility is a potentia l route of exposure, volatil ity and subsequent deposition will not be quantified because there are currently no valid models that would be useful to quantify this potential route of exposure to terrestrial environments. Pendimethalin is a semi-volatile compound that may be lost from moist soil. The vol atilization half-life from moist soil was found to be 12.5 days (MRID 00153766). Pendimethalin has been observed at low concentrations (0.143 ppb ma ximum) in rainwater in California (Vogel et al., 2008). This effect was accounted for in the PRZM-EXAMS modeling by invoking

4 7the PRZM volatilization routine, thus allowing volatilization to compete with runoff and metabolism as a dissipation route. Comparis on of the highest EEC scenario (forestry) shows that the effect is small (16.6 ppb w ith volatility invoked and 18.1 ppb without). The relatively slow volatilization rate from even moist soil is not believed to result in as large or immediate an aquatic exposure as sp ray drift at the time of application. Thus, airborne exposure is adequately quantifie d by the spray drift an alysis. Terrestrial exposure of plants and animals is accountedfor by the AgDrift and AgDISP effect area analysis.

2.10.1.2 Measures of Effect

Data identified in Section 2.8 are used as measures of effect for direct and indirect effects to the CRLF. Data were obtained from regi strant submitted studies or from literature studies identified by ECOTOX. The ECOTOXicology database(ECOTOX) was searched in order to provide more ecological effects data and in an attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX wa s created and is maintained by the USEPA, Office of Research and Devel opment, and the National Health and Environmental Effects Research Laboratory's Mid- Continent Ecology Division.

The assessment of risk for direct effect s to the terrestrial-phase CRLF makes the assumption that toxicity of pendimethalin to bird s is similar to or less than the toxicity to the terrestrial-phase CRLF. The same assu mption is made for fish and aquatic-phase CRLF. Algae, aquatic invertebrates, fish, and amphibians represent potential prey of theCRLF in the aquatic habitat. Terrestrial invertebrates, small mammals, and terrestrialphase amphibians represent potential prey of th e CRLF in the terrestrial habitat. Aquatic, semi-aquatic, and terrestrial plants represent habitat of CRLF.

The acute measures of effect used for animal s in this screening level assessment are the LD 50 , LC 50and EC 50 . LD stands for "Lethal Dose", and LD 50is the amount of a material, given all at once, that is estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” and LC 50is the concentration of a chemical that is estimated to kill 50% of the test organisms. EC stands for “Effective Concentration” and the EC 50is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non-listed animals are the NOAEL/NOAEC an d NOEC. NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest tested dose of a substance that has been reported to have no harmful (adve rse) effects on test organisms. The NOAEC ( i.e. , “No-Observed-Adverse-Effect -Concentration”) is the highest test concentration at which none of the observed effects were statis tically different from the control. The NOEC is the No-Observed-Effects-Concentration. For non-listed plants, only acute exposures are assessed ( i.e. , EC 25 for terrestrial plants and EC 50for aquatic plants).
It is important to note that the measures of effect for direct and indirect effects to the CRLF and its designated critical habitat are as sociated with impacts to survival, growth,

4 8and fecundity, and do not include the full suite of sublethal effects used to define the action area. According the Overview Docu ment (USEPA 2004), the Agency relies on effects endpoints that are either direct measures of impairme nt of survival, growth, or fecundity or endpoints for which there is a scientifically robust, peer reviewed relationship that can quantify the impact of the measured effect endpoint on the assessment endpoints of survival, growth, and fecundity.

2.10.1.3 Integration of Exposure and Effects
Risk characterization is the integration of exposure and ecological e ffects characterization to determine the potential ecolo gical risk from agricultural and non-agricultural uses of pendimethalin, and the likelihood of direct a nd indirect effects to CRLF in aquatic and terrestrial habitats. The expos ure and toxicity effects data are integrated in order to evaluate the risks of adverse ecological effects on non-target species. For the assessment of pendimethalin risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divided by acute and chronic toxicity values. The resulting RQs are then compared to the Ag ency’s levels of c oncern (LOCs) (USEPA, 2004) (see Appendix C).
For this endangered species assessment, listedspecies LOCs are used for comparing RQ values for acute and chronic exposures of pendimethalin directly to the CRLF. If estimated exposures directly to the CRLF of pendimethalin re sulting from a particular use are sufficient to exceed the listed species LOC, then the effects determination for that use is “may affect”. When considering indirect effects to the CRLF due to effects to animal prey (aquatic and terrestrial invertebrates, fish, frogs, and mice), the listed species LOCs are also used. If estimated exposures to CRLF prey of pendimethalin resulting from a particular use are sufficient to exceed th e listed species LOC, then the effects determination for that use is a “may affect.” If the RQ being considered also exceeds the non-listed species acute risk LOC, then the eff ects determination is a LAA. If the acute RQ is between the listed species LOC and th e non-listed acute risk species LOC, then further lines of evidence ( i.e . probability of individual effects, species sensitivity distributions) are considered in distinguishing between a determination of NLAA and a LAA. When considering indirect effects to the CRLF due to effects to algae as dietary items or plants as habitat, the non-listed sp ecies LOC for plants is used because the CRLF does not have an obligate relationship with any particular aquatic and/or terrestrial plant. If the RQ being considered for a particul ar use exceeds the non-listed species LOC for plants, the effects determination is “may affect”. Further information on LOCs is provided in Appendix C.



### 3.0 Exposure Assessment
Pendimethalin is formulated as granules and emulsifiable concentrate. Application equipment includes ground application, and aerial application. Risks from ground boom

4 9and aerial applications are e xpected to result in the hi ghest off-target levels of pendimethalin due to generally higher spray drift levels. Ground boom and aerial modes of application tend to use lower volumes of application applied in finer sprays than applications coincident with sprayers and spreaders and thus have a higher potential for off-target movement via spray drift.

3.1 Label Application Rates and Intervals Pendimethalin labels may be categorized into two types: labels for manufacturing uses (including technical grade pendimethalin and its formulated products) and end-use products. While technical products, which co ntain pendimethalin of high purity, are not used directly in the environment, they are used to make formulated products, which can be applied in specific areas to control grasse s and certain broadleaf weeds in agricultural crops, orchards, landscapes and rights-of-way. The formulated pr oduct labels legally limit pendimethalin’s potential use to only those sites that are specified on the labels.
There are no known pending mitigations that would influence the exposure assessment.
Currently registered agricu ltural and non-agricultural uses of pendimethalin within California are summarized in Table 3-1.

Table 3-1 Pendimethalin Uses, Scenario s, and Application Information for the CRLF risk assessment 1
Scenario Uses Represented by Scenario Application Rate Application Method

Scenario Uses Represented Application rate (lb/acre) Application method CAalfalfa_WirrigOP alfalfa 3.98 air CAalmond_WirrigSTD nut trees 5.985 ground CAalmond_WirrigSTD nut trees 3.96 air Cacitrus_WirrigSTD citrus crops 5.985 ground Cacitrus_WirrigSTD citrus crops 3.96 air CAcolecropRLF cole crops 0.99 air

CAcornOP field corn, sweet corn, popcorn 1.98 air Cacotton_WirrigSTD cotton 1.98 air CAForestryRLF forestry 3.96 air Cafruit_WirrigSTD fruit trees 3.96 air CAgarlicRLF garlic 1.485 air Cagrapes_WirrigSTD grapes 5.845 ground Cagrapes_WirrigSTD grapes 3.96 air CAmelonsRLF eggplant 1.485 air CAOliveRLF olives 3.96 air CAOnion_WirrigSTD onion 1.98 air CApotatoRLF potato, white/Irish 1.485 air CArowcropRLFartichoke/asparagus 3.895 airCAStrawberrynoplasticRLF strawberry 1.485 air

5 0Scenario Uses Represented by Scenario Application Rate Application Method
Catomato_WirrigSTD tomato, tomatillo 1.485 ground CAtomatoSTD groundcherry 1.485 air CARightofWayfRLF, CAImperviousRLF rights-of-way 3.96 air CAwheatRLF wheat 1.485 air Tier 1 Rice Model rice 0.99 air 1 Uses assessed based on memorandum from SRRD (Verification Memorandum for Pendimethalin for Red Legged Frog Assessment) dated 2/17/2009.

3.2 Aquatic Exposure Assessment

3.2.1 Modeling Approach
Aquatic exposures are quantitatively estimatedfor all of assessed uses using scenarios that represent high exposure sites for pendimetha lin use. Each of these sites represents a 10 hectare field that drains into a 1-hectare pond that is 2 meters deep and has no outlet. Exposure estimates generated using the standard pond are intended to represent a wide variety of vulnerable water bodi es that occur at the top of watersheds including prairie pot holes, playa lakes, wetlands, vernalpools, man-made and natural ponds, and intermittent and first-order streams. As a group, there are factors that make these water bodies more or less vulnerable than the standard surrogate pond. Static water bodies that have larger ratios of drainage area to water body volume would be expected to have higher peak EECs than the standard pond. These water bodies will be either shallower or have large drainage areas (or both). Shallow water bodies te nd to have limited additional storage capacity, and thus, tend to overflow and carry pesticide in the discharge whereas the standard pond has no discharge. As wa tershed size increases beyond 10 hectares, at some point, it becomes unlikely that the entire watershed is planted to a single crop, which is all treated with the pesticide. Headwater streams can also have peak concentrations higher than the standard pond, but they tend to persist for only short periods of time and are then carried downstream.
Crop-specific management practices for all of the assessed uses of pendimethalin were used for modeling, including application rates, number of applications per year, application intervals, and the firs t application date for each crop.

The Tier 1 Rice Model calculate s the water column concentration in a flooded rice paddy on the day of application, accounting only fo r sorption to sediment as a dissipation mechanism.
KABAM is used to estimate potential bi oaccumulation of hydrophobic organic pesticides in freshwater aquatic ecosystems and risk s to mammals and birds consuming aquatic organisms which have bioaccumulated these pesticides. This tool can also be used to estimate pesticide concentrations in fish tissu es consumed by humans (i.e., filets). The bioaccumulation portion of KABAM is base d upon work by Arnot and Gobas (2004) who parameterized a bioaccumulation model ba sed on PCBs and some pesticides (e.g.,

5 1lindane, DDT) in freshwater aquatic ecosystem s. KABAM relies on a chemical's octanolwater partition coefficient (KOW) to estimate uptake and eliminati on constants through respiration and diet of organisms in different trophic levels. Pesticide tissue residues are calculated for different levels of an aquatic food web. The model then uses pesticide tissue concentrations in aquatic animals to estimate dose- and dietary-based exposures and associated risks to mammals and bird s consuming aquatic organisms, using an approach that is similar to the TREX model (USEPA 2008). Input parameters for KABAM are given in Appendix K.

3.2.2 Model Inputs

Pendimethalin is a herbicide used on a wide variety of food, non-food crops, and nonagricultural sites. Pendimethalin environmental fate data used for generating model parameters is listed in Table 2.1 in Section 2.4.1. The input parameters for PRZM and EXAMS are in Table 3-2 . Application dates were ge nerally one to two weeks before the crop emergence date in the PRZM scenario, as pendimethalin is a pre-emergence/preplant herbicide. Table 3-2 Summary of PRZM/EZAMS Envi ronmental Fate Data Used for Aquatic Exposure Inputs for Pendimethalin Endangered Species Assessment for the CRLF 1

Fate Property Value (unit) MRID (or source) Molecular Weight 281.31
Henry’s constant 8.6E-7 atm-m3/mol VP/solubility
Vapor Pressure 3.0E-5 mmHg 00153766

Solubility in Water 3.0 mg/L at 25oC 00153762; 10x actual value as per Input Parameter Guidance (IPG) Photolysis in Water 42 day half-life (12 hours light/dark) 00153763

Aerobic Soil Metabolism Half-lives 172 days 40185104; deviation from IPG as explained in 1997 RED Hydrolysis Stable 00106777

Aerobic Aquatic Metabolism (water column) 330 day half-life (total system)3x factor not used due to long halflife from single study 47385201
Anaerobic Aquatic Metabolism (benthic) 208 day half-life 40813501; upper 90 th%ile confidence bound

Koc 17040 mL/g o.c. 43041901 (average of 5 values) Application rate and frequency See table 3.1 Application intervals
Chemical Application Method (CAM) Soil appl;ied

5 2Fate Property Value (unit) MRID (or source)
Application Efficiency 0.99 ground 0.95 aerial IPG

Spray Drift Fraction 0.01 ground 0.05 aerial IPG

Air Diffusion coefficient 3427 cm2/day = 1.55/(MW)^0.65
Enthalpy of Vaporization 20 kcal/mol PRZM default 1 – Inputs determined in accordance with EFED “Guidance for Chemistry and Management Practice Input Parameters for Use in Modeling the Environmental Fateand Transport of Pesticides” dated February 28, 2002

3.2.3 Results The aquatic EECs for the various scenarios and application practices are listed in Table 3-3

. Most peak exposures were 16 ppb or be low. Most exposures were dominated by spray drift.

Table 3-3 Aquatic EECs ( μ g/L) for Pendimethalin Uses in California

PRZM Scenario Application Rate (lb/A) Aerial/ Ground Specific Crop Peak EEC (ppb) 21-day EEC (ppb) 60-day EEC (ppb)
CAcolecropRLF 0.99 A Several cole crops 3.16 1.29 0.98
Cacitrus_WirrigSTD a 5.985 G Several citrus crops 3.42 0.94 0.58 Cagrapes_WirrigSTD, CAwinegrapesRLF 5.845 G grapes 4.06 1.31 0.95
CApotatoRLF1.485 A potato, white/Irish 4.14 0.99 0.57 CAtomatoSTD 1.485 A groundcherry 4.21 1.10 0.66 CAmelonsRLF 1.485 A eggplant 4.22 1.04 0.62 CAgarlicRLF 1.485 A garlic 4.31 1.15 0.73CAStrawberrynoplasticRLF 1.485 A strawberry 4.74 1.92 1.36 CAOnion_WirrigSTD 1.98 A onion 5.55 1.35 0.80 Cacotton_WirrigSTD 1.98 A cotton 5.75 1.54 0.99 CAwheatRLF 1.485 A wheat 6.10 2.81 2.13 CAalmond_WirrigSTD 5.985 G several 6.56 2.38 1.61 CAcornOP 1.98 A several 6.84 2.00 1.54 Cacitrus_WirrigSTD a 3.96 A several 11.06 2.65 1.52 CAOliveRLF3.96 A olives 11.16 2.78 1.70 Cafruit_WirrigSTD b 3.96 A several 11.18 3.03 1.85 CAalfalfa_WirrigOP 3.98 A alfalfa 11.28 3.11 1.95 Cagrapes_WirrigSTD, CAwinegrapesRLF 3.96 A grapes 11.44 2.94 1.83 CAalmond_WirrigSTD c 3.96 A several 11.71 3.68 2.30
CArowcropRLF d 3.895 A artichoke/asp aragus 11.92 4.04 2.86

5 3CAForestryRLF e 3.96 A several 16.60 6.41 4.93 Tier 1 Rice Model 0.99 A rice 48 --- --- CARightofWayfRLF, CAImperviousRLF f 3.96 A several 1.74 0.55 0.36

aThis scenario represents calamondin, citron (citrus), citrus hybrids other than tangelo, grapefruit , kumquat, lemon, lime, orange, pummelo (shaddock), and tangelo

. bThis scenario represents apple, apricot, cherry, cr abapple, fig, loquat, nectarine, peach, pear, pepin o (melon pear), plum, pomegranate, prune, quince, and small fruits

. cThis scenario represents almond, beech nut, brazil nut, butternut, cashew, ches tnut, chinquapin, filbert (hazelnut), hickory nut, macadamia nut (bushnut), mayhaw (hawthorn), pecan, pi stachio, walnut (Englis h or black)

. d This scenario represents artichoke, asparagus, beans, carrot (including tops), garbanzos (including chic k peas), legume vegetables, peanuts (unspecified), peas, and pepper

. eThis scenario represents forestry and Christmas tree plantations

. f These combined scenarios represents airports/landing fields, commercial/industri al lawns, golf cours e turf, industrial areas (outdoor), mulch, ornamental and/or shade trees, ornamental ground cover, ornamenta l herbaceous plants, ornamental lawns and turf, ornamental non-flowering plants, ornamental sod farm (turf) , ornamental woody shrubs and vines, paved areas (private roads/sidewalks), Rights-of-way, fencerows , hedges recreation area lawns, residential lawns, and shelterbelt plantings. Combined EEC is 50 % Impervious scenario with 1% of application rateand no drift, and 50% Rights-of-way scenario

. 3.2.4 Existing Monitoring Data
A critical step in the process of characteri zing EECs is comparing the modeled estimates with available surface water monitoring data. Included in this assessment are pendimethalin data from the USGS NAWQA program ( http://water.usgs.gov/nawqa ) and data from the California Department of Pesticide Regulation (CDPR).

3.2.4.1 USGS NAWQA Surface Water Data
Data for pendimethalin and its degradate hydroxypendamethalin were downloaded from the NAWQA Data Warehouse site on March 30, 2009. The data was restricted to California sampling stations. There were 604 measurements of pendimethalin in the Sacramento River and San Joaquin-TulareRiver basins. There was measureable pendimethalin in 319 of the 604 samples (53% positive).
The highest concentration recorded (0.679 ppb) was at a station called “Highline Cn Spill Nr Hilmar Ca” in the San Joaquin-Tulare Rive r Basin. All 9 measurements at this site were positive for pendimethalin, with a range of 0.262 to 0.679 ppb.
All 8 measurements of hydroxypendimethalin in surface water were in the San JoaquinTulare basin. All were non-detect (<0.143 ppb).

3.2.4.2 USGS NAWQA Groundwater Data

5 4There were 589 measurements of pendimethalinin the NAWQA data for the Sacramento River and San Joaquin-Tulare River Basins. There was only one positive result (0.0138 ppb) in Stanislaus County (San Joaquin-Tulare basin).
All 61 measurements of pendimethalin in gr ound water were in the San Joaquin-Tulare basin. All were non-detect (<0.143 ppb).

3.2.4.3 California Department of Pesticide Regulation (CPR) Data
Data for pendimethalin were downloaded fr om the California surface water monitoring database on March 19, 2009. There were 565 measurements of pendimethalin in the Sacramento River valley (33 were positive), and 1802 measurements (326 were positive) in the San Joaquin River valley. The maxi mum concentration in the Sacramento River valley was 0.7 ppb, and it was 3.5 ppb in the San Jo aquin valley. The data for all stations in the two valleys are given in Figure 3.1 below.

Pendimethalin [ug/L] in Sacramento Valley Streams

0.8

0.7

0.6

0.5

0.4 Conc [ug/L]

0.3

0.2

0.1

0 5/7/1990 1/31/1993 10/28/1995 7/24/1998 4/19/2001 1/14/2004 10/10/2006 7/6/200 9 datePendimethalin, ppb

5 5Pendimethalin [ug/L] in San Joaquin Valley Streamsppb Pendimethalin 4

3.5

3

2.5

2 Conc [ug/L]

1.5

1

0.5

0 5/7/1990 1/31/1993 10/28/1995 7/24/1998 4/19/2001 1/14/2004 10/10/200 6 date

Figure 3.1 California DPR surface water monitoring data

3.2.4.4 Atmospheric Monitoring Data

Pendimethalin has been detected in air in an agricultural setting (Merced River basin downstream from McSwain dam) in Californi a (Vogel et al. 2008). Of 23 rainwater samples taken, 78% were positive, with a maximum concentration of 0.143 μg/L, and a median of 0.021 μg/L. Sampling was conducted in 2003 and 2004.
As explained above in section 2.10.1.1, volatili zation and redeposition is not quantifiable with currently approved models. However, an alysis of water mode ling results with and with soil volatilization ro utines invoked indicate that the volatilization effect is small for pendimethalin, and airborne exposure is dominated by spray drift at the time of application.

3.2.4.5 Spray Drift Buffer and Downstrea m Dilution Analysis for Action Area
Because pendimethalin use is documented in 54 of 58 California counties, and because it is semi-volatile and has been detected in rainwater, the Action Area is considered to be the entire state. Spray drift and downstream dilution analysis for the Action Area were therefore not conducted.

5 63.3 Terrestrial Animal Exposure Assessment
T-REX (Version 1.3.1) is used to calc ulate dietary and dose-based EECs of pendimethalin for the CRLF and its potential prey ( e.g . small mammals and terrestrial insects) inhabiting terrestrial areas. EECs us ed to represent the CRLF are also used to represent exposure values for frogs serving as potential prey of CRLF adults. T-REX simulates a 1-year time period. For this asse ssment, spray applications of pendimethalin are considered, as discussed in below.
Terrestrial EECs for foliar formulations of pendimethalin were derived for the uses summarized in Table 3.4. Given that no data on interception and subsequent dissipation from foliar surfaces is available for pendimethal in, a default foliar diss ipation half-life of 35 days is used based on the work of Willis and McDowell (1987). Use of specific input values, including number of applications, appl ication rate and app lication interval are provided in Table 3.4 . Outputs from T-REX is available in Appendix E

.
Table 3-4 Input Parameters for Foliar A pplications Used to Derive Terrestrial EECs for Pendimethalin with T-REX

Use Sites Application rate (lbs ai/A) Number of Applications walnut (english/black), tangerines, tangelo, small fruits, pummelo (shaddock), pomegranate, pistachio, pecan, orange, macadamia nut

(bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin, chestnut, cashew, calamondin, butternut, brazil nut, beech nut, almond, grapes. 6.0 1

Prune, plum, pear, peach, olive, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, indus trial areas (outdoor), forest trees (all or unspecified), Christmas treeplantations, recreation area lawns,

loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa 4.0 1

Asparagus, artichoke 3.9 1 golf course turf, airports/landing fields 3.5 1 residential lawns 3.0 1 Shallot, onion, corn (sweet, pop, field) 2.0 1 Carrot 1.9 1 Sunflower 1.73 1 Tomato, tomatillo, tobacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snapor lima) beans, dried-type beans, cotton, cowpea (southern pea, blackeyed bean), 1.485 1

Wheat, pepper, pepino (melon pear), groundcherry, eggplant 1.425 1 Strawberry 1.485 2 (30 day interval) Legume vegetables 1.24 1 Rice, mustard cabbage (gai choy, pak-choi), kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 1

T-REX is also used to calculate EECs for terrestrial insects exposed to pendimethalin. Dietary-based EECs calculated by T-REX for small and large insects (units of a.i./g) are used to bound an estimate of exposure to terrestrial insects. Av ailable acute contact

57toxicity data for bees exposed to pendimethalin(in units of μg a.i./bee), are converted to μg a.i./g (of bee) by multiplying by 1 bee/0.128 g. The EECs are later compared to the adjusted acute contact toxicity data for bees in order to derive RQs.
For modeling purposes, exposures of the CRL F to pendimethalin through contaminated food are estimated using the EECs for the small bird (20 g) which consumes small insects. Dietary-based and dose-based exposur es of potential prey are assessed using the small mammal (15 g) which consumes short grass. Upper-bound Kenega nomogram values reported by T-REX for these two organi sm types are used for derivation of EECs for the CRLF and its potential prey ( Table 3.5 ). Dietary-based EECs for small and large insects reported by T-REX as well as the resulting adjusted EECs are available in Table 3.6

. An example output from T- REX v. 1.3.1 is available in Appendix E

.
Table 3-5 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based Exposures of the CRLF and its Prey to Pendimethalin

Application rate EECs for CRLF (including other frog prey) EECs for Prey (small mammals) Dietary-based

EEC (ppm) Dose-based EEC (mg/kg-bw) Dietary-based EEC (ppm) Dose-based EEC (mg/kg-bw) 6.0 810 922 1,440 1374 4.0 540 615 960 915 3.9 526 600 936 892 3.5 472 538 840 801 3.0 405 461 720 686 2.0 270 307 480 458 1.9 256 292 456 435 1.73 234 267 415 396 1.485 200 228 356 340 1.425 192 219 242 326 1.485 (2 applications) 301 342 535 510 1.24 167 191 298 284 1.0 135 154 240 229

Table 3-6 EECs (ppm) for Indirect E ffects to the Terrestrial-Phase CRLF via Effects to Terrestrial Invertebrate Prey Items
Application Rate Small Insect Large Insect

6.0 810 90 4.0 540 60 3.9 527 59 3.5 473 53 3.0 405 45 2.0 270 30 1.9 257 29 1.73 234 26

5 81.485 200 22 1.425 192 21 1.485 (2 applications) 342 38 1.24 167 19 1.0 135 15

3.4 Terrestrial Plant Exposure Assessment
TerrPlant (Version 1.1.2) is used to calculate EECs for non-target plant species inhabiting dry and semi-aquatic areas. Parameter values for application rate and drift assumption are based upon the use and re lated application method ( Table 3.7 ). A runoff value of 0.01 is utilized based on pendimethalin’s sol ubility, which is 0.28 mg/L. For aerial and ground application methods, drift is assumed to be 5% and 1%, respectively. EECs relevant to terrestrial plants consider pesticide concentratio ns in drift and in runoff. These EECs are listed by use in Table 3.7 . An example output from TerrPlant v.1.2.2 is available in Appendix F.

Table 3-7 TerrPlant Inputs and Resultin g EECs for Plants Inhabiting Dry and Semi-aquatic Areas Exposed to Pendimethalin via Runoff and Drift

Application rate (lbs a.i./A) Application method Drift Value

(%) Spray drift EEC (lbs a.i./A) Dry area EEC (lbs a.i./A) Semi-aquatic area EEC (lbs a.i./A)

6.0 Foliar - ground 1 0.060 0.120 0.660 4.0 Foliar - ground 1 0.040 0.080 0.440 4.0 Foliar - aerial 5 0.200 0.24 0.600 3.9 Foliar - ground 1 0.039 0.078 0.429 3.9 Foliar - aerial 5 0.195 0.234 0.585 3.5 Foliar - ground 1 0.035 0.070 0.385 3.5 Foliar - aerial 5 0.175 0.210 0.525 3.0 Foliar - ground 1 0.030 0.060 0.330 3.0 Foliar - aerial 5 0.150 0.180 0.450 2.0 Foliar - ground 1 0.020 0.040 0.220 2.0 Foliar - aerial 5 0.100 0.120 0.300 1.9 Foliar - ground 1 0.019 0.038 0.209 1.9 Foliar - aerial 5 0.095 0.114 0.285 1.73 Foliar - ground 1 0.017 0.035 0.190 1.73 Foliar - aerial 5 0.087 0.104 0.260 1.485 Foliar - ground 1 0.015 0.030 0.163 1.485 Foliar - aerial 5 0.074 0.089 0.223 1.24 Foliar - ground 1 0.012 0.025 0.136 1.24 Foliar - aerial 5 0.062 0.074 0.186 1.0 Foliar - ground 1 0.010 0.020 0.110 1.0 Foliar - aerial 5 0.050 0.060 0.150

5 9

### 4.0 Effects Assessment This assessment evaluates the potential for pendimethalin to directly or indirectly affect the CRLF or affect its designated criticalhabitat. As discussed in Section 2.7, assessment endpoints for the CRLF effects determination in clude direct toxic effects on the survival, reproduction, and growth of CRLF, as well as in direct effects, such as reduction of the prey base or modification of its habitat. In addition, potential modification of critical habitat is assessed by evaluating effects to th e PCEs, which are components of the critical habitat areas that provide esse ntial life cycle needs of the CRLF. Direct effects to the aquatic-phase of the CRLF are based on toxic ity information for freshwater fish, while terrestrial-phase effects are based on avian to xicity data, given that birds are generally used as a surrogate for terrestrial-phase am phibians. Because the frog’s prey items and habitat requirements are dependent on th e availability of fr eshwater fish and invertebrates, small mammals, terrestrial invertebrates, and aquatic a nd terrestrial plants, toxicity information for these taxa are also discussed. Acute (short-term) and chronic (long-term) toxicity information is characte rized based on registrant-submitted studies and a comprehensive review of the open literature on pendimethalin.
As described in the Agency’s Overview Document (U.S. EPA, 2004), the most sensitive endpoint for each taxon is used for risk estimation. For this assessment, evaluated taxa include freshwater fish (also as a surrogatefor aquatic-phase amphibians), freshwater invertebrates, aquatic plants, birds (surrogatefor terrestrial-phase amphibians), mammals, terrestrial invertebrates, and terrestrial plants.
Toxicity endpoints are established 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 main tained by EPA/Office of Research and Development (ORD) (U.S. EPA, 2004). Open l iterature data presented in this assessment were obtained from ECOTOX on 10/31/2008. Inorder to be included in the ECOTOX database, papers must meet the following minimum criteria:
(1 ) the toxic effects are related to single chemical exposure; (2 ) the toxic effects are on an aquatic or terrestrial plant or animal species; (3 ) there is a biological effect on live, whole organisms; (4 ) a concurrent environmental chemicalconcentration/dose or application rate is reported; and (5 ) there is an explicit duration of exposure.
Data that pass the ECOTOX screen are ev aluated along with the registrant-submitted data, and may be incorporated qualitatively or quantitatively into this endangered species assessment. In general, effects data in the open literature that are mo re conservative than the registrant-submitted data are considered. The degree to which open literature data are quantitatively or qualitatively characterized for the effects determination is dependent on whether the information is relevant to the assessment endpoints ( i.e. , maintenance of CRLF survival, reproduction, and gr owth) identified in Section 2.8. For example, endpoints such as behavior modifications are likely to be qualitativ ely evaluated, because

6 0quantitative relationships between modifications and reduction in species survival, reproduction, and/or growth ar e not available. Although the effects determination relies on endpoints that are relevant to the asse ssment endpoints of survival, growth, or reproduction, it is important to note that the full suite of sublethal endpoints potentially available in the effects literature (regardle ss of their significance to the assessment endpoints) are considered to definethe action area for pendimethalin.
Citations of all open literaturenot considered as part of this assessment because they were either rejected by the ECOTOX screenor accepted by ECOTOX but not used (e.g., the endpoint is less sensitive) are included in Appendix G. Appendix G also includes a rationale for rejection of those studies that did not pass the ECOTOX screen and those that were not evaluated as part of this endangered species risk assessment. A detailed spreadsheet of the available EC OTOX open literature data, including the full suite of lethal and sublethal endpoints is presented in Appendix G. Appendix I also includes a summary of the human health effects data for pendimethalin.
In addition to registrant-submitted and open lite rature toxicity information, other sources of information, including use of the acute pr obit dose response relationship to establish the probability of an individual effect and re views of the Ecological Incident Information System (EIIS), are conducted to further refi ne the characterization of potential ecological effects associated with exposure to pendimeth alin. A summary of the available aquatic and terrestrial ecotoxicity information, use of the probit dose res ponse relationship, and the incident information for pendime thalin are provided in Sections 4.1 through 4.4, respectively.
There are no available toxicity informati on on the degradates of pendimethalin.
A detailed summary of the available ecot oxicity information for all pendimethalin formulated products are pr esented in Appendix A.
In regards to mixtures of other products containing pendimethalin, only three products (EPA Reg. Nos. 241-331, 241-376 and 5905- 495) have definitive product LD 50values with associated confidence intervals. Although there are no 95% confidence intervals associated with the pendimethalin technical, an evaluation of the three products listed above show that for EPA Reg. Nos. 241-331 and 241-376, the product LD 50 values can be attributed solely to the toxicity of pendimethalin. When these product LD 50 s (3506 and 2500 mg/kg, respectively) and associatedconfidence intervals (892-1223 and 504-800 mg/kg, respectively) are adjusted for th e percent pendimethalin (30.24% and 25.4%, respectively), the adjusted LD50 values for EPA Reg. No. 241-331 (1060 mg/kg, CI: 892-1223) and EPA Reg. No. 241-376 (635 mg/kg, CI: 504-800) are not toxicologically distinct from the LD 50of pendimethalin (1050 mg/kg). Similarly, for EPA Reg. No. 5905-495, the toxicity can be attributed to pr opanil. When the LD50 for this product (1110 mg/kg) and its confidence interval (913- 1360 mg/kg) are adjust ed for the percent propanil (33.7%), the adjusted LD 50value of 374 mg/kg (CI: 308-458 mg/kg) is within a factor of two of the confid ence interval for propanil ( 1080 mg/kg; CI: 868-1343 mg/kg) and the difference is not considered to be toxicologically significant.

6 1Because the active ingredients are not expect ed to have similar mechanisms of action, metabolites, or toxicokinetic behavior, it is reasonable to conclude that an assumption of dose-addition would be inappropriate. Conse quently, an assessment based on the toxicity of pendimethalin is the only reasonable appr oach that employs the available data to address the potential acute risks of the formul ated products. Additional information can be found in Appendix B.

4.1 Evaluation of Aquati c Ecotoxicity Studies

Table 4-1 summarizes the most sensitive aquatic toxicity endpoints for the CRLF, based on an evaluation of both the submitted studies and the open literature, as previously discussed. A brief summary of submitted and open literature data considered relevant to this ecological risk assessment for the CRLF is presented below. Additional information is provided in Appendix A.

Table 4-1 Freshwater Aquatic Toxicity Profile for Pendimethalin
Assessment Endpoint Species Toxicity Value Used in Risk Assessment Describe effect (i.e. mortality, growth, reproduction) Citation MRID # (Author & Date) Study Classification

Acute DirectToxicity to AquaticPhase CRLF Rainbow trout LC 50= 138 ppb mortality 00046291 Sleight, 1972 Acceptable

Chronic DirectToxicity to AquaticPhase CRLF Fathead minnow NOAEC = 6.3 ppb reduction of egg production 00037940 EG&G Bionomics, 1975 Acceptable

Indirect Toxicity to Aquatic-Phase CRLF via Acute Toxicity to Freshwater Invertebrates (i.e. prey items) Daphnia magna EC 50= 280 ppb mortality 00059738 LeBlanc, 1976 Acceptable

Indirect Toxicity to Aquatic-Phase CRLF via Chronic Toxicity to Freshwater Invertebrates (i.e. prey items) Waterflea (Daphnia magna) NOAEC = 14.5 ppb reduced production of Daphnia young 00100504 Graney, 1981 Acceptable

Indirect Toxicity to Aquatic-Phase CRLF via Toxicity to Non-vascular Aquatic Plants Marine diatom Skeletonem a costatum EC 50= 5.2 ppb growth 42372205 Hughes, 1992 Acceptable

Indirect Toxicity to Aquatic-Phase CRLF via Toxicity to Vascular Aquatic Duckweed (Lemna gibba ) EC 50= 12..5 ppb growth 42137101 Hughes, 1992 Acceptable

6 2Assessment Endpoint Species Toxicity Value Used in Risk Assessment Describe effect (i.e. mortality, growth, reproduction) Citation MRID # (Author & Date) Study Classification

Plants

Toxicity to aquatic fish and invertebrates is categorizedusing the system shown in Table 4-2 (U.S. EPA, 2004). Toxicity categories fo r aquatic plants have not been defined.

Table 4-2 Categories of Acute Toxicityfor Fish and Aquatic Invertebrates LC 50(ppm) Toxicity Category < 0.1 Very highly toxic > 0.1 - 1 Highly toxic > 1 - 10 Moderately toxic > 10 - 100 Slightly toxic > 100 Practically nontoxic

4.1.1 Toxicity to Freshwater Fish Given that no pendimethalin toxicity data are available for aquatic-phase amphibians; freshwater fish data were used as a surrogateto estimate direct acuteand chronic risks to the CRLF. Freshwater fish toxicity data were also used to assess poten tial indirect effects of pendimethalin to the CRLF. Effects to freshwater fish resulting from exposure to pendimethalin could indirectly affect th e CRLF via reduction in available food. As discussed in Section 2.5.3, over 50% of the prey mass of the CRLF may consist of vertebrates such as mice, frogs, and fish (Hayes and Tennant, 1985).
A summary of acute and chr onic freshwater fish data, including data from the open literature, is provide d below in Sections 4.1.1.1 through 4.1.1.3.

4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies
Three acute freshwater studies using the technical pendimethalin and seven using formulations were submitted to the Agency. For the technical pendimethalin studies, the LC 50for the three species of fish range from 138 ppb to 418 ppb. For the formulated product studies, three species of fishrange from 520 ppb formulation to 86,600 ppb formulation.
The species for the three technical pendimeth alin studies are blue gill sunfish, rainbow trout, and channel catfish. The LC 50for the species are 199 ppb, 138 ppb, and 418 ppb, respectively.
The species for the seven formulated product studies are bluegill sunfish, rainbow trout, and channel catfish. The LC50 for the formulation studies are listed below:

LC 50(ppm LC 50(ppm a.i

. AI 1 formulation) calculated) MRI D

6 3Bluegill sunfish Prowl 3E Lepomis macrochirus 34.4% 1.04 ppm 0.358 ppm 00037927 Rainbow trout Prowl 3E Oncorhynchus mykiss 34.4% 1.0 ppm 0.344 ppm 00037927 Bluegill sunfish Prowl 4E Lepomis macrochirus 42.3% 0.92 ppm 0.389 ppm 00037927 Rainbow trout Prowl 4E Oncorhynchus mykiss 42.3% 0.52 ppm 0.220 ppm 00037927 Bluegill sunfish Avenge 2AS Lepomis macrochirus 31.8% 90.4 ppm 28.747 ppm 00037927 Rainbow trout Avenge 2AS Oncorhynchus mykiss 31.8% 86.6 ppm 27.539 ppm 00037927 Channel catfish Prowl 4E Ictalurus punctatus 42.3% 1.9 ppm 0.804 ppm 00131773 1 AI refers to active ingredient percentage. The formulated product is also displayed. The endpoint selected for the assessment is the rainbow trout study using technical grade pendimethalin and it had an LC 50of 138 ppb (C.I. 110-170) since it is the most sensitive of the freshwater fish. The MRID number is 00046291.

4.1.1. 2 Freshwater Fish: Chronic Exposure (Early Life Stage and Reproduction) Studies
One chronic freshwater fish study (MRID 00037940) was submitted to the Agency. This study is a Fathead minnow ( Pimephales promelas ) full life cycle study using a technical grade pendimethalin. The 288-day NOAE C is 6.3 ppb (0.0063 ppm). The NOAEC is based on reduction of egg production. The LOAEC = 9.8 ppb (0.0098 ppm) based on reduction of egg production. Reduced hatchabil ity was also observed at 22 and 43 ppb.

4.1.1. 3 Freshwater Fish: Sublethal Effects and Additional Open Literature Information
The ecotoxicity studies from the ECOTOX database provided endpoints that are less sensitive than the submitted rainbow trout study (MRID 00046291) which had an LC 50of 138 ppb. No useful chronic freshwater inve rtebrate studies were found in the ECOTOX database with NOAEC more sensitive than the submitted fathead minnow study (MRID 00037940).

4.1.1. 4 Aquatic-phase Amphibian: Ac ute and Chronic Studies

No studies are available.

6 44.1.2 Toxicity to Freshwater Invertebrates Freshwater invertebrate toxici ty data were used to assess potential indire ct effects of pendimethalin to the CRLF. Effects to fres hwater invertebrates re sulting from exposure to pendimethalin could indirectly affect th e CRLF via reduction in available food items. As discussed in Section 2.5.3, the main food source for juven ile aquatic- and terrestrialphase CRLFs is thought to be aquatic inve rtebrates found along the shoreline and on the water surface, including aquatic sowbugs, larval alderf lies and water striders.
A summary of acute and chronic freshwater invertebrate data , including data published in the open literature, is provided below in Sections 4.1.2.1 through 4.1.2.3.

4.1.2. 1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies

Three acute freshwater invertebrate studies were submitted to the Agency: two studies using the waterflea Daphnia magna and one using crayfish, Procambarus simulans

.
A Daphnia magna study using technical grade pendimethalin had an EC 50of 280 ppb (C.I. 230-330) and is considered to be an acceptable study. The other Daphnia magna study used the formulation containing 45.6% active ingredient with the EC50 = 5.1 ppm (5100 ppb) formulation. This study is consider ed to be acceptable for formulated study.
The crayfish study is categorized as supplemen tal due to the precipitate being observed in concentrations of 1.0 ppm and more; the dissolved O 2concentration is less than 40% of saturation; and DMSO was used as a solvent which tends to increase mortalities rather than decrease them. This EC 50for this study is greater than 1.0 ppm (1000 ppb).
Acute toxicity of pendimethalintechnical to freshwater invertebrates is categorized as highly toxic and moderately toxic. Pendi methalin formulation is categorized as moderately toxic.
The most sensitive freshwater invertebrate species tested is Daphnia magna , with a 48­ hour EC 50value of 280 μg/L (MRID: 00059738), is used for deriving risk quotients for the CRLF prey.

4.1.2. 2 Freshwater Invertebrates: Chronic Exposure (Reproduction) Studies One chronic freshwater invertebrate study (MRID 00100504) was submitted to the Agency. This study is a Daphnia magna life cycle study using a technical grade pendimethalin. The 21-day NOAEC is 14.5 ppb (0.0145 ppm). The NOAEC is based on reduced production of Daphnia. LOAE C = 0.0172 ppm (17.2 ppb). Mortality was observed in the study with 100% mortality at the 2 highest dose levels of 35.8 and 74.2 ppb. No appreciable mortality observed at 3 lowest concentration levels of 4.3, 8.2, and 14.5 ppb. Reduction of productivity of 50% occurred at 22.1 and 17.5 ppb concentration levels.

6 54.1.2. 3 Freshwater Invertebrates: Sublethal Effects and Open Literature Data
The ecotoxicity studies from the ECOTOX database provided endpoints that are less sensitive than the submitted Daphnia magna study (MRID 00059738) which had an EC 50 of 280 ppb. No useful chronic freshwater invertebrate studies were found in the ECOTOX database with NOAEC moresensitive than the submitted Daphnia magna study (MRID 00100504).

4.1.3 Toxicity to Aquatic Plants Aquatic plant toxicity studies were used as one of the measures of effect to evaluate whether pendimethalin may affect primary production and the availability of aquatic plants as food for CRLF tadpoles. Primary productivity is essential for indirectly supporting the growth and abundance of the CRLF.
Only laboratory studies were used to determine whether pendimethalin may cause direct effects to aquatic plants since there are no available field studies to evaluate the effects of pendimethalin to aquatic plants. A summary of the laboratory data for aquatic plants is provided in Sections 4.1.3.1 and 4.1.3.2 .

4.1.3. 1 Aquatic Plants: Laboratory Data
Aquatic plant toxicity data submitted to the Agency show a range of EC 50values from 5.2 ppb to >174 ppb. The most sensitive species tested are the greenalgae and marine diatom and the least sensitive species is the cyanobacteria (blue-green algae). Below is a listing of the species tested and their toxicity value:

EC 50(ppb) NOAELMRID
Green algae ( Selenastrum capricornutum ) 5.4 ppb 3.0 42372204

Marine diatom ( Skeletonema costatum ) 5.2 ppb 0.7 42372205

Freshwater diatom (Navicula pelliculosa ) 6.7 ppb 3.2 42372206
Blue-green algae ( Anabaena flos-aquae ) >174 ppb 98 42372207
Duckweed (Lemna gibba ) 12.5 ppb 5.6 42137101 The endpoint selected for the assessment is the marine diatom study using technical grade pendimethalin had an EC 50of 5.2 ppb since it is most sens itive of the aquatic plants tested. In addition, the duckweed is the onl y vascular aquatic plan t tested and will be used for assessing aquatic habitat. The EC 50for the duckweed is 12.5 ppb.

6 64.1.3.2 Freshwater Field Studies

No studies are available.

4.2 Toxicity of Pendimethalin to Terrestrial Organisms

Table 4.3 below summarizes the most sensitive terrestrial toxicity endpoints for the CRLF, based on an evaluation of both the s ubmitted studies and the open literature. A brief summary of submitted and open literature data considered relevant to this ecological risk assessment for the CRLF is presented below. Table 4-3. Terrestrial Toxici ty Profile for Pendimethalin Assessment Endpoint Species Toxicity Value Used in Risk Assessment Describe effect (i.e. mortality, growth, reproduction) Citation MRID # (Author & Date) Study Classification

Acute Dosebased Direct Toxicity toTerrestrialPhase CRLF Mallard duck LD 50= 1421 mg/kg-bw mortality 00059739 Fink, 1976 Acceptable

Acute Dietarybased Direct Toxicity toTerrestrialPhase CRLF Bobwhite quail LC 50= 4187 ppm mortality 00026675 Fink, 1973 Acceptable

Chronic Direct Toxicity toTerrestrialPhase CRLF Mallard duck NOAEC = 141 ppm 14-day survivor bodyweight 44907601 Beavers, 1996 Acceptable

Indirect Toxicity toTerrestrialPhase CRLF (via acute toxicity to mammalian prey items) Rat LD 50= 1050 mg/kg-bw mortality 00026657 Acceptable

Indirect Toxicity toTerrestrialPhase CRLF (via chronic toxicity to mammalian prey items) Rat NOAEL = 25 mg/kg-bw (500 ppm) decreases in the number of pups born and pup weights 41725203 Acceptable

Indirect Toxicity toTerrestrialHoney bee LD 50= >49.8 μgm/bee mortality 00099890 Atkins, Acceptable

6 7Assessment Endpoint Species Toxicity Value Used in Risk Assessment Describe effect (i.e. mortality, growth, reproduction) Citation MRID # (Author & Date) Study Classification

Phase CRLF (via acute toxicity to terrestrial invertebrate prey items) Indirect Toxicity to Terrestrial- and Aquatic-Phase Seedling Emergence Monocots Ryegrass EC 25 = 0.01 lb ai/A Dry weight 42372201 Chetram, 1992 Acceptable

CRLF (via toxicity to terrestrial plants) Seedling Emergence Dicots Lettuce EC 25 = 0.09 lb ai/A Dry weight 42372201 Chetram, 1992 Acceptable

Vegetative Vigor Monocots Ryegrass EC 25 = 0.034 lb ai/A Dry weight 42372203 Chetram, 1992 Acceptable

Vegetative Vigor Dicots Lettuce EC 25 = 0.10 lb ai/A Dry weight 42372203 Chetram, 1992 Acceptable

Acute toxicity to terrestrial animals is categ orized using the classi fication system shown in Table 4-44 (U.S. EPA, 2004). Toxicity categories for terrestrial plants have not been defined.

Table 4-4 Categories of Acute Toxicity for Avian and Mammalian Studies
Toxicity Category Oral LD 50 Dietary LC 50 Very highly toxic < 10 mg/kg < 50 ppm Highly toxic 10 - 50 mg/kg 50 - 500 ppm Moderately toxic 51 - 500 mg/kg 501 - 1000 ppm

Slightly toxic 501 - 2000 mg/kg 1001 - 5000 ppm Practically non-toxic > 2000 mg/kg > 5000 ppm

4.2.1 Toxicity to Birds
As specified in the Overview Document, the Agency uses birds as a surrogate for terrestrial-phase amphibians when amphibian to xicity data are not available (U.S. EPA, 2004). No terrestrial-phase amphibian data are available for pendimethalin; therefore, acute and chronic avian toxicity data are used to asse ss the potential dire ct effects of pendimethalin to terrestrial-phase CRLFs.

6 84.2.1.1 Birds: Acute Exposure (Mortality) Studies

Two subacute LC 50dietary avian studies and one acute LD 50oral acute avian study using the technical pendimethalin were submitted to the Agency. For the LC 50dietary studies, the LC 50for the bobwhite quail is 4187 ppm and th e mallard duck is >4640 ppm. For the acute LD 50for the mallard, the LD 50is 1421 mg/kg-bw.
The endpoint selected for the assessment is the bobwhite quail’s LC 50of 4187 ppm (MRID 00026674) and the mallard’s LD 50of 1421 mg/kg-bw (00059739).
Pendimethalin technical is categorized as slig htly toxic on subacute dietary and acute oral basis to birds. No avian studies using pendimethalin formulated product have been submitted to the Agency.

4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies
Two avian reproduction studies were submitted to the Agency. No treatment related effects were observed in the bobwhite quail and the LOAEL is greater than 1410 ppm. The mallard duck study (MRID 44907601) showed the parameter of 14-day survivor bodyweight was reduced at 1410 ppm. The NO AEL for the mallard study is 410 ppm. No other treatment related effects were observed. This study is classified as acceptable.

4.2.1.3 Birds: Open Literature Studies

No studies more sensitive than the submitted avian studies were found in the ECOTOX database.

4.2.2 Toxicity to Mammals
Mammalian toxicity data are used to assess po tential indirect effects of pendimethalin to the terrestrial-phase CRLF. Effects to small mammals resulting from exposure to pendimethalin could also indirectly affect the CRLF via reduction in available food. As discussed in Section 2.5.3, over 50% of the prey mass of the CRLF may consist of vertebrates such as mice, frogs, and fish (Hayes and Tennant, 1985).

Most recent data and information on mammalian toxicity comes from Registration Division document entitled “Pendimethalin. Human Health Risk Assessment for the Proposed Food Uses of the Herbic ide on Artichoke, Globe; Asparagus; Brassica Head and Stem Vegetables, Subgroup 5A; and Grape (PP#6E7129)”, dated August 22, 2007. The document was authored by Debra Rate, Ph.D ., Biologist, Alternative Risk Integration and Assessment (ARIA), Risk Integration, Minor Use, and Emergency Response Branch (RIMUERB), Registration Division (RD) ( 7505P) to Barbara Madden/ Susan Stanton RIMUERB/RD (7505P). This is found in Appendix I.

6 94.2.2.1 Mammals: Acute Exposure (Mortality) Studies
The Agency’s rat acute oral assessment endpoint for risk assessment purpose shows the LD 50to be 1250 mg/kg (male) and 1050 mg/kg (female) (MRID 00026657). Pendimethalin is considered to be slightly toxic to mammals on an acute oral basis.

4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies
A 2-generation reproduction study (MRID 41725203) with pendimethalin was reviewed by HED. The parental systemic NOAEL was 25 mg/kg/day ( 500 ppm ), based on decreased body weight gain and food cons umption at the LOAEL of 125 mg/kg/day ( 2500 ppm ). The reproductive/offspring NOAEL is 25 mg/kg/day ( 500 ppm ), based on decreases in the number of pups born and pup weight at the LOA EL of 125 mg/kg/day ( 2500 ppm ). Parental and reproductive NOAELs and LOAELs were based on a generic ratio (1:20) of dietary intake of chemical.

The HED Cancer Peer Review Committee cl assified pendimethalin as a “Group C” (possible human) carcinogen, based on thyroid follicular ce ll adenomas in rats. The committee recommended a non-quantitative appr oach (non-linear, RfD approach) since mode of action studies are avai lable that demonstrate that th e thyroid tumors are due to a thyroid-pituitary imbalance, and also since pendimethalin was shown to be nonmutagenic in mammalian somatic cells and germ cells.

4.2.2.3 Mammals: Open Literature Studies

No studies more sensitive than the submitted mammalian studies were found in the ECOTOX database.

4.2.3 Toxicity to Terrestrial Invertebrates

Terrestrial invertebrate toxici ty data are used to assess pot ential indirect effects of pendimethalin to the terrestrial-phase CRLF. Effects to terrestrial invertebrates resulting from exposure to pendimethalin may also in directly affect the CRLF via reduction in available food.

4.2.3.1 Terrestrial Invertebrates: Acut e Exposure (Mortality) Studies
Only one acute oral bee toxicity study (MRI D ) was submitted to the Agency. This study was authored by Dr. Atkins in 1974. Th e species tested is the honey bee, Apis mellifera

. The LD50 acute oral is greater than 49.8 μg/bee with no mortal ity observed at the highest tested dose. Pendimethalin is classified as practically non-toxic to the honey bee.

7 04.2.3.2 Terrestrial Invertebrates: Open Literature Studies

No studies more sensitive than the submitted bee study were found in the ECOTOX database.

4.2.4 Toxicity to Terrestrial Plants
Terrestrial plant toxicity data are used to evaluate the potential for pendimethalin to affect riparian zone and upland vegetation within the action area for the CRLF. Impacts to riparian and upland (i.e., grassl and, woodland) vegetation may resu lt in indirect effects to both aquatic- and terrestrial-phase CRLFs, as well as modification to designated critical habitat PCEs via increased se dimentation, alteration in water quality, and reduction in of upland and riparian habitat that provides shelter, foraging, predator avoidance and dispersal for juvenile and adult CRLFs.
Plant toxicity data from both registrant-submitted studies and studies in the scientific literature were reviewed for this assessment. Registrant-submitted studies are conducted under conditions and with species defined in EPA toxicity test gui delines. Sub-lethal endpoints such as plant growth, dry weight, and biomass are evaluated for both monocots and dicots, and effects are evaluated at both seedling emergence and vegetative life stages. Guideline studies generally evaluate toxicity to ten crop species. A drawback to these tests is that they are conducted on herbaceous crop species only, and extrapolation of effects to other species, such as th e woody shrubs and trees and wild herbaceous species, contributes uncertainty to risk conclusions.
Commercial crop species have b een selectively bred, and may be more or less resistant to particular stressors than wild herbs and forb s. The direction of this uncertainty for specific plants and stressors, including pe ndimethalin, is largel y unknown. Homogenous test plant seed lots also lack the genetic vari ation that occurs in natural populations, so the range of effects seen from tests is likely to be smaller than would be expected from wild populations.
The results of the Tier II seedling emergence and vegetative vigor toxicity tests on nontarget plants are summarized below in Table 4-55

.
Table 4-5 Non-target Terrestrial Plant Seedling Emergence and Vegetative Vigor Toxicity (Tier II) Data
Crop Species NOAEC (lb ai/A) EC 25 (lb ai/A) Most sensitive parameter Seedling Emergence Monocots Oat, Avena sativa 0.25 1.0 Plant height

7 1Crop Species NOAEC (lb ai/A) EC 25 (lb ai/A) Most sensitive parameter Ryegrass, Lolium perenne 0.065 1 0.01 Dry weight Corn, Zea mays 0.5 0.68 Plant height Onion, Allium cepa 0.06 0.08 Dry weight Dicots Soybean, Glycine max 2.0 4.7 Dry weight Lettuce, Lactuca sativa 0.063 0.09 Dry weight Radish, Rhaphanus sativus 0.13 0.86 Plant height Tomato, Lycopersicon esculentum 0.13 0.2 Dry weight
Cucumber, Cucumis sativus 0.25 2.4 Plant height Cabbage, Brassica oleracea 0.25 0.44 Plant height Vegetative Vigor Monocots Oat, Avena sativa 0.5 0.78 Dry weight Ryegrass, Lolium perenne 0.0008 0.034 Dry weight Corn, Zea mays 2.0 2.8 Plant height Onion, Allium cepa 0.50 0.56 Plant height Dicots Soybean, Glycine max 0.13 0.27 Dry weight Lettuce, Lactuca sativa 0.003 0.10 Dry weight Radish, Rhaphanus sativus >4.0 >4.0 n/a Tomato, Lycopersicon esculentum 0.13 0.5 Dry weight
Cucumber, Cucumis sativus >4.0 >4.0 n/a Cabbage, Brassica oleracea 2.0 4.8 Dry weight 1 EC05 was used in lieu of NOEAC since study was unable to determine NOAEC value

4. 3 Use of Probit Slope Response Relation ship to Provide Information on the Endangered Species Levels of Concern The Agency uses the probit dose response relationship as a tool for providing additional information on the potential for acute direct effects to individuallisted species and aquatic animals that may indirectly affect the listed species of concern (U.S. EPA, 2004). As part of the risk characterization, an interpretation of acute RQ for listed species is discussed. This interpretation is presented interms of the chance of an individual event (i.e., mortality or immobilization) should expos ure at the EEC actually occur for a species with sensitivity to pendimethalin on par with the acute toxicity endpoi nt selected for RQ calculation. To accomplish this interpretati on, the Agency uses the slope of the dose response relationship available from the toxicitystudy used to establish the acute toxicity measures of effect for each taxonomic group that is relevant to this assessment. The individual effects probability associated with the acute RQ is based on the mean estimate of the slope and an assumption of a probit dose response relationshi p. In addition to a single effects probability es timate based on the mean, upper and lower estimates of the effects probability are also pr ovided to account for variance in the slope, if available.
Individual effect probabilitie s are calculated based on an Ex cel spreadsheet tool IECV1.1 (Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP, Environmental Fate and Effects Division (J une 22, 2004). The model allows for such calculations by entering the mean slope estimate (and the 95% confidence bounds of that

7 2estimate) as the slope parameter for the spread sheet. In addition, the acute RQ is entered as the desired threshold.

4.4 Incident Database Review EPA maintains an incident database system (Ecological Incident Information System or EIIS) to track and evaluate accidental kills a ssociated with pesticide use. The likelihood that a particular pesticide caused the incide nt is classified as “highly probable”, “probable”, “possible”, or “unlikely”, based on the information contained in the incident report.
A review of the EIIS database for ecologi cal incidents involvi ng pendimethalin was completed on April 16, 2009. The results of this review for terrestrial, plant, and aquatic incidents are discussed below in Sections 4.4.1 through 4.4.3, respectively. A complete list of the incidents involv ing pendimethalin including associated uncertainties is included as Appendix H

. In the years since EPA has maintained the database, a total of 69 incidents were reported, of which 65 related to terrestrial plants.

4.4.1 Terrestrial Incidents

There were two incidents i nvolving pendimethalin with alleged adverse effects to terrestrial animals (Ameri can Robin, Rock dove, Ground squirrel, and an “unknown” bird.)
In a 1998 Kansas incident (I007495-001) twelve robins and rock doves were killed. It is not known as to what site the pendimethalinwas applied but was applied nearby. No toxicological analysis was reportedly taken; therefore no confirmation was made as to whether pendimethalin was responsible for the deaths of the 12 birds. Pendimethalin is slightly toxic on an acute oral and subacute di etary basis to birds. It is uncertain that pendimethalin was responsibl e for the bird deaths.
There was also an incomplete incident report (I002343-001) involving surface application of pendimethalin and fertilizer granules to turf with mortality of unknown numbers of ground squirrel and an “unknown” bird. The corpses were analyzed for organophosphates (OP) but not for pendimethali n. No OPs were found. Pendimethalin is slightly toxic on an acute oral and subacute di etary basis to birds and small mammals. It is uncertain and not likely that pendimethalin is responsible for the deaths of the squirrels and the bird.

7 34.4.2 Plant Incidents
Most of these plant incidents related to th e treated crop itself, including corn, soybean, potatoes, lawns, azalea bushes, and peanuts. So me of the incidents occur from spray drift and runoff. Of the 65 reported alleged inci dents involving pendimethalin, four of the incidents were from spray drift to nearby non-target plants. The seve rity of these plant incidents ranged from plant damage (most incidents) to mortality. The following reported alleged incidents are from spray drif t or runoff from treate d sites to non-target plants:
I014702-053 - In Wisconsin, pendimethalin wa s applied with clomazone to soybean. The two herbicides drifted over to raspberry plants and trees causing some damage to these plants. The damage symptoms observe d were more consistent with clomazone damage than pendimethalin. Pendimethalin may have contributed to plant damage but the symptoms of plant damage to non-target pl ants are more consistent with clomazone. It is probable that pendimethalin may be involved with non-target plant damage.
B000621-001 – In 1986 in Illinois, pendimethalin was applied with clomazone to soybean field. The two herbicides drifted over to damage nearby lawns, fruit trees, and vegetable gardens. The damage symptoms observed were more consistent with clomazone damage than pendimethalin. Pendimethalin may have contributed to plant damage but the symptoms of plant damage to non-target plants are more consistent with clomazone. It is probable that pendimethalin may be involved with non-target plant damage.
I0009262-054 – In 1996 in California, a greenhouse floor was sprayed with pendimethalin. Vapor from the spray drifte d onto potted azaleas pl ants sitting on the benches above the floor. 172,636 potted azaleas we re unmarketable. It is likely that pendimethalin contributed to damage to azaleas from volatility.
I013587-052 – In 1999 in Washington State, pe ndimethalin was applied to residential ornamentals. Large tree limbs were observe d dying. Pendimethalin was analyzed and found present in the foliage of the trees.

4.4.3 Aquatic Incidents

There are two aquatic incidents reported involving mortality of 300 and 996 fish, respectively. The fish involved were bass and bluegill (300 fish) and minnow (996 fish), but the incident reports considered pe ndimethalin involvement “unlikely.”
In 1998 in Ohio, (incident I007677-001) pendime thalin and Lorsban were applied to a corn field. One inch of rain fell shortly afte rwards and runoff from the corn field ran into a pond. The distance from the field to the pond is from 14-70 feet. Approximately 300 bass and bluegills were later found dead. Fish and water samples were taken but findings

7 4were not submitted. Lorsban (chlorpyrifos) is much more toxic to aquatic animals than pendimethalin by three orders of magnitude and is more soluble in water. It is more likely that Lorsban is the cause of the mortalit y to the fish. Pendimeth alin is not expected to kill fish outright from runoff from one inch of rain on a corn field based on its EEC and toxicity.
In 1993 in Minnesota, an incident involvi ng the deaths of 996 minnows was reported. There is very little information in this report which indicated that “250 -300 gallons yellow weed killer, Prowl” c ontributed to the deaths of the minnows in the Schwerin Creek. This information comes from a Mi nnesota Department of Natural Resources report showing a table of various spill incidents involvi ng pesticides reported to Minnesota. It is likely that a significant spill of concentrated pendimethalin is the cause of deaths of the minnow in the creek.

7 5

### 5.0 Risk Characterization Risk characterization is the integration of the exposure and effects characterizations. Risk characterization is used to determine the potential for direct and/or indirect effects to the CRLF or for modification to its designated critical habitat from the use of pendimethalin risk characterization provides an estimation (Section 5.1) and a description (Section 5.2) of the likel ihood of adverse effects; articulates risk assessment assumptions, limitations, and uncertainties; and synthesi zes an overall conclusion regarding the likelihood of adverse effects to the CRLF or its designated critic al habitat (i.e., “no effect,” “likely to adversely affect,” or “may affect, but not likely to adversely affect”).

5.1 Risk Estimation Risk is estimated by calculating the ratio of e xposure to toxicity. Th is ratio is the risk quotient (RQ), which is then compared to pre-established acute and chronic levels of concern (LOCs) for each category evaluated ( Appendix C ). For acute exposures to the CRLF and its animal prey in aquatic habitats, as well as terrestrial invertebrates, the LOC is 0.05. For acute exposures to the CRLF and mammals, the LOC is 0.1. The LOC for chronic exposures to CRLF and its prey, as well as exposures to plants is 1.0.
Risk to the aquatic-phase CRLF is estimated by calculating the ratio of exposure to toxicity using 1-in-10 year EECs based on the label-recommended pendimethalin usage scenarios summarized in Table 3-3 and the appropriate aquati c toxicity endpoint from Table 4-1 . Risks to the terrestrial-phase CRLF and its prey ( e.g . terrestrial insects, small mammals and terrestrial-phase frogs) are es timated based on exposures resulting from applications of pendimethalin (Tables 3.5 – 3.6) and the appropriate toxicity endpoint from Table 4.3 . Exposures are also derived for terrestrial plants, as discussed in Section 3.7 and toxicity summarized in Section 4.2.4, based on the highest ap plication rates of pendimethalin use within the action area.

5.1.1 Exposures in the Aquatic Habitat

5.1.1.1 Direct Effects to Aquatic-Phase CRLF
Direct effects to the aquatic -phase CRLF are based on peak EECs in the standard pond and the lowest acute toxicity value for freshwat er fish. In order to assess direct chronic risks to the CRLF, 60-day EECs and the lowest chronic toxicity value for freshwater fish are used. Based on exceedances of the acute LOC (0.05) for listed species
, pendimethalin may directly affect the aquatic- phase of the CRLF. The results of the RQ calculations are in Table 5.1 below.

7 6Table 5-1 Summary of Direct Effect RQs afor the Aquatic-phase CRLF EEC Scenario Peak EEC ( μ g/L) b 60-day EEC ( μ g/L) b Acute RQ Chronic RQ Probability of Individual Effect at ES LOC Probability of Individual Effect at RQ
CAForestryRLF (forest trees and Christmas tree plantations) 16.6 4.9 0.12 0.8 e 1 in 5.85E+04 (1 in 30.5 to 1 in 1.73E+16 ) c

CArowcropRLF g 11.9 2.9 0.09 <1.0 e 1 in 7.91E+05 (1 in 54.8 to 1 in

4.10E+20 ) c Rice model (Rice) 48 Not available 0.35 Not applicable 1 in 49.8 (1 in 5.53 to 1 in

4.91E+04 ) c Cagrapes_WirrigSTD, CAwinegrapesRLF (grapes) 11.4 1.8 0.08 <1.0 e 4.18E+08 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c CAalmond_WirrigSTD h11.7 2.3 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c CATurfRLF j 11.5 1.9 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c CAalfalfa_WirrigOP (alfalfa, lupine) 11.3 2.0 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c Cafruit_WirrigSTD i 11.2 1.9 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c CAOliveRLF (olives) 11.2 1.7 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c Cacitrus_WirrigSTD K 11.1 1.5 0.08 <1.0 e 1 in 2.51E+06 (1 in 70.8 to 1 in

3.64E+22 ) c CAcornOP (corn and sunflower) 6.8 d 1.5 0.05 <1.0 e 1 in 4.18E+08 (1 in 216 to 1 in

1.75E+31 ) c

aRQs associated with acute and chronic direct toxicity to the CRLF are also used to assess potential indirect effects to the CRLF based on a reduction in freshwater fish and frogs as food items. The toxicity value used as surrogate species is rainbow trout LC 50 of 138 ppb ( μ g/L) and Fathead minnow NOAEC of 6.3 ppb ( μ g/L)

. bThe highest EEC based on foliar use of pendimethalin on forestry at 4.0 lb ai/A (see Table 3-3)

. cA probit slope value for the acute rainbow trout toxi city test is not availabl e; therefore, the effec t probability was calculated based on a default slope assumption of 4.5 with upper and lower 95 % confidence intervals of 2 and 9 (Urban and Cook, 1986). Not calculated for chronic endpoints

. dPeak EEC below 6.8 ppb will result in RQ < acute endangered species LOC of 0.05

. eRQ < chronic LOC of 1.0

. gThis scenario represents artichoke, asparagus, beans, carrot (including tops), garbanzos (including chic k peas), legume vegetables, peanuts (unspecified), peas, and pepper

. h This scenario represents almond, beech nut, brazil nut, butternut, cashew, chestnut, chinquapin, filbert (hazelnut), hickory nut, macadamia nut (bushnut), mayhaw (hawthorn), pecan, pi stachio, walnut (Englis h or black ) iThis scenario represents apple, apricot, cherry, cr abapple, fig, loquat, nectarine, peach, pear, pepin o (melon pear), plum, pomegranate, prune, quince, and small fruits

. j This scenario represents commercial/industrial lawns, golf course turf, ornamental lawns and turf, ornamental sod farm (turf), recreation area lawns, and residential lawns

.

7 7K This scenario represents calamondin, citron (citrus), citrus hybrids other than tangelo, grapefruit, kumquat, lemon, lime, orange, pummelo (shaddock), and tangelo.

5.1.1. 2 Indirect Effects to Aquatic-Phas e CRLF via Reduction in Prey (non-vascular aquatic plants, a quatic invertebrates, fish, and frogs) 

### a) Non-vascular Aquatic Plants

Indirect effects of pendimethalin to the aquatic-phase CRLF (tadpoles) via reduction in non-vascular aquatic plants in its diet are based on peak EECs from the standard pond and the lowest toxicity value (EC 50 ) for aquatic non-vascular plants. Based on exceedances of the acute LOC (1.0) for aquatic plants, pendimethalin is likely to indirectly affect the CRLF via reduction in non-vascular plants. The results of the RQ calculations are in Table 5.2 below.

Table 5-2 Summary of RQs Used to Esti mate Indirect Effects to the CRLF via Effects to Non-Vascular Aquatic Plants a(diet of CRLF in ta dpole life stage and habitat of aquatic-phase CRLF)

Uses Application rate (lb ai/A) and type Peak EEC (μg/L) Indirect effects RQ* (food and habitat) Rice model (Rice) 1 lb ai/A (aerial) 48 9.2 CAForestryRLF (forest trees and Christmas tree plantations) 4 lb ai/A (aerial) 16.6 b 3.2 CArowcropRLF e 4 lb ai/A (aerial) 11.9 2.3 CAalmond_WirrigSTD f 4 lb ai/A (aerial) 11.7 2.3 CATurfRLF h 4 lb ai/A (aerial) 11.5 2.2 Cagrapes_WirrigSTD, CAwinegrapesRLF (grapes) 4 lb ai/A (aerial) 11.4 2.2 CAalmond_WirrigSTD f 6 lb ai/A (ground) 6.6 1.3 CAalfalfa_WirrigOP (alfalfa, lupine) 4 lb ai/A (aerial) 11.3 2.2 Cafruit_WirrigSTD g 4 lb ai/A (aerial) 11.2 2.2 CAOliveRLF (olives) 4 lb ai/A (aerial) 11.2 2.2 Cacitrus_WirrigSTD i 4 lb ai/A (aerial) 11.1 2.1 CAcornOP (corn and sunflower) 2 lb ai/A (aerial) 6.8 1.3 CAwheatRLF (sorghum and wheat) 1.5 lb ai/A (aerial) 6.1 1.2 CAcotton_WirrigSTD (cotton) 2 lb ai/A (aerial) 5.8 1.1 CAOnion_WirrigSTD (onion and shallot) 2 lb ai/A (aerial) 5.6 c 1.1 * LOC exceedances (RQ > 1) are bolded and shaded. RQ = use-specific peak EEC/ marine diatom ( Skeletonema costatum ) EC 50 of 5.2 ppb.

aThe toxicity value used as surrogate species is marine diatom ( Skeletonema costatum ) EC 50of 5.2 pp b ( μ g/L)

. bThe highest EEC based on foliar use of pendimethalin is on forestry at 4.0 lb ai/A (see Table 3-3)

. cPeak EEC below 5.2 ppb will result in RQ < acute LOC of 1.0

.

78eThis scenario represents artichoke, asparagus, beans, carrot (including tops), garbanzos (including chic k peas), legume vegetables, peanuts (unspecified), peas, and pepper

. f This scenario represents almond , beech nut, brazil nut, butternut, cas hew, chestnut, chinquapin, filbert (hazelnut), hickory nut, macadamia nut (bushnut), mayhaw (hawthorn), pecan, pi stachio, walnut (Englis h or black )
gThis scenario represents apple, apricot, cherry, cr abapple, fig, loquat, nectarine, peach, pear, pepin o (melon pear), plum, pomegranate, prune, quince, and small fruits

. h This scenario represents commercial/industrial lawn s, golf course turf, ornamental lawns and turf, ornamental sod farm (turf), recreation area lawns, and residential lawns

. i This scenario represents calamondin, citron (citrus), citrus hybrids other than tangelo, grapefruit, kumquat , lemon, lime, orange, pummelo (shaddock), and tangelo

.


### b) Aquatic Invertebrates

Indirect acute effects to the aquatic-phase CRLF via effects to prey (invertebrates) in aquatic habitats are based on peak EECs in the standard pond and the lowest acute toxicity value for freshwater invertebrates. For chronic risk s, 21-day EECs and the lowest chronic toxicity value for invertebrates are us ed to derive RQs. A summary of the acute and chronic RQ values for exposure to aquati c invertebrates (as prey items of aquaticphase CRLFs) is provided in Table 5-3 . Based on the acute LOC (0.5) and chronic LOC (1.0) not being exceeded, pendimethalin has no effect, indirectly on the CRLF based on effects to aquatic invertebrates. The tabl e shows only the use sites that exceed the LOC plus the highest EEC that does not exceed the LOC.
Table 5-3 Summary of Acute and Chronic RQs aUsed to Estimate Indirect Effects to the CRLF via Direct Effects on Aquatic Inve rtebrates as Dietary Food Items (prey of CRLF juveniles and adul ts in aquatic habitats) EEC Scenario Peak EEC ( μ g/L) b 21-day EEC ( μ g/L) b Acute RQ Chronic RQ Probability of Individual Effect at ES LOC Probability of Individual Effect at RQ

Rice model (Rice) 48 Not available 0.17 f Not applicable 1 in 3,740 (1 in 16.2 to 1 in 4.62E+11) c CAForestryRLF (Forest trees and Christmas tree plantations) 16.6 6.4 0.06 b 0.4 e 1 in 5.22E+07 (1 in 138 to 1 in 5.04E+27) c

CArowcropRLF h ( artichoke/asparagus) 11.9 4.0 0.04 f <1.0 e Not applicable

aRQs associated with acute and chronic direct toxicity to the CRLF are also used to assess potential indirect effects to the CRLF based on a reduction in freshwater fish and frogs as food items. The toxicity value used as surrogate species is Daphnia magna EC 50 of 280 ppb ( μ g/L) and Daphnia magnaNOAEC of 14.5 ppb ( μ g/L)

. bThe highest EEC based on foliar use of pendimethalin on forestry and Christmas trees at 4.0 lb ai/A (se e Table 3-3 )

. cA probit slope value for the acute Daphnia magnatoxicity test is not available; therefore, the effec t probability was calculated based on a default slope assumption of 4.5 with upper and lower 95 % confidence intervals of 2 and 9 (Urban and Cook, 1986). Not calculated for chronic endpoints

. dPeak EEC below 5.2 ppb will result in RQ < acute endangered species LOC of 0.05

. eRQ < chronic LOC of 1.0

. f RQ < acute LOC of 0.5

.

7 9hThis scenario represents artichoke, asparagus, beans, carrot (including tops), garbanzos (including chick peas), legume vegetables, peanuts (unspecified), peas, and pepper. 

### c) Fish and Frogs

Fish and frogs also represent potential prey items of adult aquatic-phase CRLFs. RQs associated with acute and chronic direct to xicity to the CRLF (Table 5.1) are used to assess potential indirect effects to the CRLF based on a reduction in freshwater fish and frogs as food items. Based on listed species LOC exceedances using the surrogate rainbow trout acute LC 50toxicity endpoint and the fathead minnow chronic NOAEC endpoint, pendimethalin may indirectly affect the CRLF via reduction in freshwater fish and frogs as food items.

5.1.1. 3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary Productivity (Freshwater Aquatic Plants)

Indirect effects to the CRLF vi a direct toxicity to aquatic plants are estimated using the most sensitive non-vascular and vascular plant toxicity endp oints. Because there are no obligate relationships between the CRLF and any aquatic plant species, the most sensitive EC 50 values, rather than NOAEC values, were us ed to derive RQs. Based on vascular aquatic plant LOC (1.0) exceedances, pendimethalin may indirectly affect the CRLF via reduction in vascular plants from uses on forestry and Christmas tree plantations and from rice use. Table 5-4 shows only the use sites that exceed the LOC plus the highest EEC that does not exceed the LOC.

Table 5-4 Summary of RQs Used to Esti mate Indirect Effects to the CRLF via Effects to Vascular Aquatic Plants (habitat of aquatic-phase CRLF) a

Uses Application rate (lb ai/A) and type Peak EEC (μg/L) Indirect effects RQ* (food and habitat) Rice model (Rice) 1 lb ai/A (aerial) 48 3.8 CAForestryRLF (forest trees and Christmas tree plantations) 4 lb ai/A (aerial) 16.6 1.3

aRQs used to estimate indirect effects to the CRLF vi a toxicity to vascular aquatic plants are summarized in Table 5.2. The toxicity value used as surrogate species is duckweed ( Lemna gibba ) EC 50of 12.5 ppb ( μ g/L). bThe highest EEC based on foliar use of pendimethalin on forestry at 4.0 lb ai/A (see Table 3-3).

cPeak EEC below 12.5 ppb will result in RQ < acute LOC of 1.0. * = LOC exceedances (RQ > 1) are bolded. RQ = use-specific peak EEC / duckweed EC 50of 12.5 ppb.

5.1.2 Exposures in the Terrestrial Habitat

5.1.2. 1 Direct Effects to Terrestrial-phase CRLF

80Potential direct acute effect s to the terrestrial-phase CRL F are derived by considering dose- and dietary-based EECs modeled in T- REX for a small bird (20 g) consuming small invertebrates (Table 3.5) and acute oraland subacute dietary toxicity endpoints for avian species.

Potential direct chronic effect s of pendimethalin to the terre strial-phase CRLF are derived by considering dietary-based exposures m odeled in T-REX for a small bird (20g) consuming small invertebrates. Chronic eff ects are estimated using the lowest available toxicity data for birds. EECs are divided by toxicity values to estimate chronic dietarybased RQs.
Based on RQ exceedances of listed species acu te LOC (0.1) and chronic LOC (1.0) from all use sites, pendimethalin may directly affect the terrestrial-phase of the CRLF.

Table 5-5 Summary of Acute RQs* Used to Estimate Direct Effects to the Terrestrial-phase CRLF

Use Site Application rate (lbs ai/A) Dietary-based Acute RQ 1 Dosebased Acute RQ 1 Probability of Individual Effect at RQ
walnut (english/black), tangeri nes, tangelo, small fruits, pummelo (shaddock), pomegranate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo,

citron (citrus), chinquapin, chestnut, cashew, calamondin, butternut, brazil nut, beec h nut, almond, grapes. 6.0 0.2 1.25 Dose-based: 1 in 1.5 (1 in 1.73 to 1 in 1.24 ) 2 Dietary-based: 1 in 1.5 (1 in 1.73 to 1 in 1.24 ) 2

Prune, plum, pear, peach, olive, nectarine, fig, cherry, apricot, apple, ornamental and/or shad e trees, nonagricultural rights-ofway, fencerows, hedgerows, mulc h, industrial areas (outdoor),

forest trees (all or unspecified), Christmas tree plantations, recreation area lawns, loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa 4.0 0.1 0.8 Dose-based: 1 in 3.02 (1 in 2.36 to 1 in 5.22 ) 2 Dietary-based: 1 in 2.94E+05 (1 in 44 to 8.86E+18) 2

Asparagus, artichoke 3.9 0.1 0.8 Dose-based: 1 in 3.02 (1 in 2.36 to 1 in 5.22 ) 2 Dietary-based: 1 in 2.94E+05 (1 in 44 to 8.86E+18) 2

golf course turf, airports/landing fields 3.5 0.1 0.7 Dose-based: 1 in 4.12 (1 in 2.64 to 1 in 12.2 ) 2 Dietary-based: 1 in 2.94E+05 (1 in 44 to 8.86E+18) 2

residential lawns 3.0 0.1 0.6 Dose-based: 1 in 1.5 (1 in 1.73 to 1 in 1.24 ) 2 Dietary-based: 1 in 2.94E+05 (1 in 44 to 8.86E+18) 2

Shallot, onion, corn (sw eet, pop, field) 2.0 <0.1 0.4 Dose-based: 1 in 27.3 (1 in 4.69 to 1 in 5.85E+03) 2 Dietary-based: n/a

Carrot 1.9 <0.1 0.4 Dose-based: 1 in 27.3 (1 in 4.69 to 1 in 5.85E+03) 2 Dietary-based: n/a

Sunflower 1.73 <0.1 0.4 Dose-based: 1 in 27.3 (1 in 4.69 to 1 in 5.85E+03) 2 Dietary-based: n/a Tomato, tomatillo, tobacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzo s (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, 1.485 <0.1 0.3 Dose-based: 1 in 107 (1 in 6.76 to 7.91E+05) 2 Dietary-based: n/a

8 1Use Site Application rate (lbs ai/A) Dietary-based Acute RQ 1 Dosebased Acute RQ 1 Probability of Individual Effect at RQ
cowpea (southern pea, black-eyed bean),
Wheat, pepper, pepino (melon pear), groundcherry, eggplant 1.425 <0.1 0.3 Dose-based: 1 in 107 (1 in 6.76 to 7.91E+05) 2 Dietary-based: n/a
Strawberry 1.485 (2 applications w/ 30-day interval) <0.1 0.5 Dose-based: 1 in 15.5 (1 in 4 to 1 in 832) 2 Dietary-based: n/a
Legume vegetables 1.24 <0.1 0.3 Dose-based: 1 in 107 (1 in 6.76 to 7.91E+05) 2 Dietary-based: n/a Rice, mustard cabbage (gai choy, pak-choi), kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts,

broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 <0.1 0.2 Dose-based: 1.21E+03 (1 in 12.3 to 6.33E+09) 2 Dietary-based: n/a

* = LOC exceedances (acute RQ > 0.1) are bolded and shaded. 1 Based on mallard LD 50of 1421 mg/kg-bw and bobwhite LC 50of 4187 ppm

. 2A probit slope value for the acute mallard duck and bobwhite quai l toxicity test is not availabl e; therefore, the effect prob ability was calculated based on a default slope assumption of 4.5 with upper and lower 95% confidenceintervals of 2 and 9 (Urban and Cook, 1986). Not calculated for chronic endpoints

.

Table 5-6 Summary of Chronic RQs* Used to Estimate Direct Effects to the Terrestrial-phase CRLF

Use Site Application rate (lbs ai/A) Dietary-based Chronic RQ 1
walnut (english/black), tangerines, tangelo, small fruits, pummelo (shaddock), pomegranate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin, ches tnut, cashew, calamondin,

butternut, brazil nut, beec h nut, almond, grapes. 6.0 5.7

Prune, plum, pear, peach, o live, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, industria l areas (outdoor), forest trees (all or unspecified), Christmas tree plantations, recreation area lawns, loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa 4.0 3.8

Asparagus, artichoke 3.9 3.7 golf course turf, airports/landing fields 3.5 3.35 residential lawns 3.0 2.9 Shallot, onion, corn (sweet, pop, field) 2.0 1.9 Carrot 1.9 1.8 Sunflower 1.73 1.7 Tomato, tomatillo, to bacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, cowpea (southern pea, bl ack-eyed bean), 1.485 1.4

Wheat, pepper, pepino (melon pear), groundcherry, eggplant 1.425 1.4

8 2Use Site Application rate (lbs ai/A) Dietary-based Chronic RQ 1

Strawberry 1.485 (2 applications w/ 30­ day interval) 2.1 Legume vegetables 1.24 1.2 Rice, mustard cabbage (gai choy, pak-choi), kohlrabi, cauliflower, cabba ge (Chinese), cabbage,

brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 1.0

* = LOC exceedances (chronic RQ >1) are bolded and shaded. 1 Based on bobwhite NOAEC of 141 ppm.

5.1.2. 2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in Prey (terrestrial invertebrates, mammals, and frogs)



### 5.1.2.2.1 Terrestrial Invertebrates

In order to assess the risks of pendimethalin to terrestri al invertebrates, which are considered prey of CRLF in terrestrial habitats, the honey bee is used as a surrogate for terrestrial invertebrates. The toxicity value for terrestrial invertebrates is calculated by multiplying the lowest available acute contact LD 50of greater than 49.8 μg a.i./bee by 1 bee/0.128g, which is based on the weight of an adult honey bee. EECs (μg a.i./g of bee) calculated by T-REX for small and large insect s are divided by the calculated toxicity value for terrestrial invertebrates, which is > 388.4 μg a.i./g of bee. Based on RQ ranges from 2.09 to 0.05, pendimethalin may indirectly affect the CRLF via reduction in terrestrial invertebrate prey items Table 5-7 Summary of RQs Used to Esti mate Indirect Effects to the Terrestrialphase CRLF via Direct Effects on Terrestria l Invertebrates as Dietary Food Items

Use Small Insect RQ* Large Insect RQ* Probability of Individual Effect at RQ of Small Insect walnut (english/black), tangerines, tangelo, small fruits, pummelo (shaddock), pomegranate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin, chestnut, cashew, calamondin, butte rnut, brazil nut, beech nut, almond, grapes. (6.0 lb ai/A) 2.09 0.23 1 in 1.08 (1 in 1.35 to 1 in 1.0 ) a

Prune, plum, pear, peach, o live, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, indus trial areas (outdoor), forest trees (all or unspecified), Christmas tree

plantations, recreation area lawns, loquat, shelterbelt plantings, quinc e, mayhaw, crabapple, alfalfa (4.0 lb ai/A) 1.39 0.15 1 in 1.35 (1 in 1.11 to 1 in 1.63 ) a

Asparagus, artichoke (3.9 lb ai/A) 1.36 0.15 1 in 1.38 (1 in 1.13 to 1 in 1.65) a

8 3golf course turf, airports/landing fields (3.5 lb ai/A) 1.22 0.14 1 in 1.54 (1 in 1.28 to 1 in 1.76) a
residential lawns (3.0 lb ai/A) 1.04 0.12 1 in 1.88 (1 in 1.78 to 1 in 1.95) a Shallot, onion, corn (sweet, pop, field) (2.0 lb ai/A) 0.70 0.08 1 in 4.12 (1 in 2.64 to 1 in 12.2) a
Carrot (1.9 lb ai/A) 0.66 0.07 1 in 4.8 (1 in 2.78 to 1 in 19.2) a
Sunflower (1.73 lb ai/A) 0.60 0.07 1 in 6.29 (1 in 3.04 to 1 in 43.6) a Tomato, tomatillo, to bacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, cowpea (southern pea, black-eyed b ean), (1.485 lb ai/A) 0.51 0.06 1 in 10.6 (1 in 3.58 to 1 in 236) a

Wheat, pepper, pepino (melon pear), groundcherry, eggplant (1.425 lb ai/A) 0.49 0.05 1 in 12.2 (1 in 3.73 to 1 in 377) a Strawberry (1.485 lb ai/A (2 applications w/ 30­ day interval)) 0.88 0.10 1 in 249 (1 in 2.19 to 1 in 3.24) a Legume vegetables (0.124 lb ai/A) 0.43 0.05 1 in 20.2 (1 in 4.31 to 1 in 2,060) a Rice, mustard cabbage (gai choy, pak-choi),

kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables (1.0 lb ai/A) 0.35 0.04 1 in 49.8 (1 in 5.53 to 1 in 4.91E+04) a

* = LOC exceedances (RQ > 0.05) are bolded and shaded. B ecause a definitive endpoint was not established for terrestrial invertebrates (i.e., the valu e is greater than the highest test concentration), the RQ represents an upper bound value. a A probit slope value for the acute honey bee toxicity test is not available; therefore, the effect probability was calculated based on a default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986). Probability of Individual Effect at RQ of 0.05 is 1 in 4.18E+08 (1 in 216 to 1 in 1.75E+31).

5.1.2.2.2 Mammals
Risks associated with ingestion of small mammals by large terrestrial-phase CRLFs are derived for dietary-based and dose-based exposures modeled in T-REX for a small mammal (15g) consuming short grass. Acute and chronic effects are estimated using the most sensitive mammalian toxicity data. EECs are divided by the toxicity value to estimate acute and chronic dose-based RQs as well as chronic dietary-based RQs. Based on RQ ranges from 25.0 to 6.2 for chronic effect s, pendimethalin is likely to indirectly affect the CRLF via reduction in small mammal prey items.

8 4Table 5-8 Summary of Acute and Chronic RQs* Used to Estimate Indirect Effects to the Terrestrial-phase CRLF via Direct Effects on Small Mammals as Dietary Food Items

Use (Application Rate) Chronic RQ Acute RQ
Probability of Individual Effect at RQDosebased Chronic

RQ 1 Dietarybased Chronic

RQ 2 Dosebased Acute RQ 3 walnut (english/black), tangerines, tangelo, small fruits, pummelo (shaddock), pomegranate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat, hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin, chestnut, cashew, calam ondin, butternut, brazil

nut, beech nut, almond, gr apes. (6.0 lb ai/A) 25.0 2.9 0.6 Dose-based: 1 in 6.29 (1 in 1.73 to 1 in 1.24 ) 2

Prune, plum, pear, peach, o live, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, indus trial areas (outdoor), forest trees (all or unspecified), Christmas tree

plantations, recreation area lawns, loquat, shelterbelt plantings, quinc e, mayhaw, crabapple, alfalfa (4.0 lb ai/A) 16.7 1.9 0.4 Dose-based: 1 in 27.3 (1 in 4.69 to 1 in 5.85E+03) 2

Asparagus, artichoke (3.9 lb ai/A) 16.2 1.9 0.4 Dose-based: 1 in 27.3 (1 in 4.69 to 1 in 5.85E+03) 2
golf course turf, airports/landing fields (3.5 lb ai/A) 14.6 1.7 0.35 Dose-based: 1 in 49.8 (1 in 5.53 to 1 in 4.91E+04) 2

residential lawns (3.0 lb ai/A) 12.5 1.4 0.3 Dose-based: 1 in 107 (1 in 6.76 to 1 in 7.91E+05) 2
Shallot, onion, corn (sweet, pop, field) (2.0 lb ai/A) 8.3 1.0 0.2 Dose-based: 1 in 1.21E+03 (1 in 12.3 to 1 in 6.33E+09) 2

Carrot (1.9 lb ai/A) 7.9 0.9 0.2 Dose-based: 1 in 1.21E+03 (1 in 12.3 to 1 in 6.33E+09) 2

Sunflower (1.73 lb ai/A) 7.2 0.8 0.2 Dose-based: 1 in 1.21E+03 (1 in 12.3 to 1 in 6.33E+09) 2 Tomato, tomatillo, to bacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, cowpea (southern pea, black-eyed b ean), (1.485 lb ai/A) 6.2 0.7 0.2 Dose-based: 1 in 1.21E+03 (1 in 12.3 to 1 in 6.33E+09) 2
Wheat, pepper, pepino (melon pear), groundcherry, eggplant (1.425 lb ai/A) 5.9 0.7 0.1 1 in 2.94E+05 (1 in 44 to 1 in 8.86E+18) 2

Strawberry (1.485 lb ai/A (2 applications w/ 30­ day interval)) 9.3 1.1 0.2 Dose-based: 1 in 1.21E+03 (1 in 12.3 to 1 in 6.33E+09) 2
Legume vegetables (0.124 lb ai/A) 5.2 0.6 0.1 1 in 2.94E+05 (1 in 44 to 1 in 8.86E+18) 2 Rice, mustard cabbage (gai choy, pak-choi),

kohlrabi, cauliflower, cabbage (Chinese), 4.2 0.5 0.1 1 in 2.94E+05 (1 in 44 to 1 in 8.86E+18) 2

8 5Chronic RQ Acute RQ cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables (1.0 lb ai/A) * = LOC exceedances (acute RQ > 0.1 and chronic RQ > 1) are bolded and shaded. 1 Based on dose-based EEC and pendimethalin rat NOAEL = 25 mg/kg-diet/day (500 ppm). 2 Based on dietary-based EEC and pendimethalin rat NOAEC = 25 mg/kg-diet/day (500 ppm). 3 Based on dose-based EEC and pendimethalin rat acute oral LD 50= 1050 mg/kg-bw.

5.1.2.2.3 Frogs
An additional prey item of the adult terrestrial -phase CRLF is other species of frogs. In order to assess risks to these organisms, di etary-based and dose-based exposures modeled in T-REX for a small bird (20g) consuming small invertebrates are used. See Section 5.1.2.1 and associated tables ( Table 5-65 and 5.6) for results. Based on dose-based acute RQs the range from 1.25 to 0.2 and chr onic RQs that range from 5.7 to 1.0, pendimethalin may indirectly affect the CRLF via reduction in frogs as prey items.

5.1.2. 3 Indirect Effects to CRLF via Reduction in Terrestrial Plant Community (Riparian and Upland Habitat)

Potential indirect effects to the CRLF resul ting from direct effects on riparian and upland vegetation are assessed using RQs from terrestrial plant seedling emergence and vegetative vigor EC 25 data as a screen. Based on LOC exceedances from all use sites, pendimethalin may indirectly affect the CRLF via reduction in terrestrial plants. Example output from TerrPlant v.1.2.2 is provided in Appendix F.

Table 5-9 RQs* for Monocots InhabitingDry and Semi-Aquatic Areas Exposed to Pendimethalin via Runoff and Drift

Use Application rate (lbs a.i./A) Application method Drift Value

(%) Spray drift RQ Dry area RQ Semi-aquatic area RQ walnut (english/black), tangerines,

tangelo, small fruits, pummelo (shaddock), pomegra nate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat,

hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin,

chestnut, cashew, calamondin, butternut, brazil nut, beech nut, almond, grapes. 6.0 lb ai/A ground 1 6.0 12.0 66.0

Prune, plum, pear, peach, olive, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, 4.0 lb ai/A ground1 4.0 8.0 44.0

8 6Use Application rate (lbs a.i./A) Application method Drift Value

(%) Spray drift RQ Dry area RQ Semi-aquatic area RQ industrial areas (outdoor), forest trees

(all or unspecified), Christmas tree plantations, recreation area lawns, loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa aerial 5 20.0 24.0 60.0

Asparagus, artichoke 3.9 lb ai/A ground1 3.9 7.8 42.9 aerial 5 19.5 23.4 58.5 golf course turf, airports/landing fields 3.5 lb ai/A ground1 3.5 7.0 38.5 aerial 5 17.5 21.0 52.5

residential lawns 3.0 lb ai/A ground1 3.0 6.00 33.0 aerial 5 15.0 18.0 43.0 Shallot, onion, corn (sweet, pop, field) 2.0 lb ai/A ground1 2.0 4.0 22.0 aerial 5 10.0 12.0 30.0

Carrot 1.9 lb ai/A ground1 1.9 3.8 20.9 aerial 5 9.5 11.4 28.5

Sunflower 1.73 lb ai/A ground1 1.7 3.5 19.0 aerial 5 8.7 10.4 26.0 Tomato, tomatillo, tobacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, cowpea (southern pea, black-eyed bean) 1.485 lb ai/A ground1 1.5 3.0 16.3

aerial 5 7.4 8.9 22.3 Wheat, pepper, pepino (melon pear), groundcherry, eggplant, strawberry 1.425 lb ai/A ground1 1.4 2.9 15.7 aerial 5 7.12 8.6 21.4

Legume vegetables 1.24 lb ai/A ground1 1.2 2.5 13.6 aerial 5 6.2 7.4 18.6Rice, mustard cabbage (gai choy, pakchoi), kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 lb ai/A ground1 1.0 2.0 11.0

aerial 5 5.0 6.0 15.0

* = LOC exceedances (RQ > 1) are bolded and shaded.

Table 5-10 RQs* for Dicots InhabitingDry and Semi-Aquatic Areas Exposed to Pendimethalin via Runoff and Drift

Use Application rate (lbs a.i./A) Application method Drift Value

(%) Spray drift RQ Dry area RQ Semi-aquatic area RQ walnut (english/black), tangerines,

tangelo, small fruits, pummelo (shaddock), pomegra nate, pistachio, pecan, orange, macadamia nut (bushnut), lime, lemon, kumquat,

hickory nut, grapefruit, filbert (hazelnut), citrus hybrids other than tangelo, citron (citrus), chinquapin,

chestnut, cashew, calamondin, butternut, brazil nut, beech nut, almond, grapes. 6.0 lb ai/A ground 1

0.7 1.3 7.3

8 7Use Application rate (lbs a.i./A) Application method Drift Value

(%) Spray drift RQ Dry area RQ Semi-aquatic area RQ Prune, plum, pear, peach, olive, nectarine, fig, cherry, apricot, apple, ornamental and/or shade trees, nonagricultural rights-of-way, fencerows, hedgerows, mulch, industrial areas (outdoor), forest trees

(all or unspecified), Christmas tree plantations, recreation area lawns, loquat, shelterbelt plantings, quince, mayhaw, crabapple, alfalfa 4.0 lb ai/A ground1

0.4 0.9 5.9

aerial 5
2.2 2.7 6.7 Asparagus, artichoke 3.9 lb ai/A ground1 0.4 0.9 4.8 aerial 5 2.2 2.6 6.5 golf course turf, airports/landing fields 3.5 lb ai/A ground1 0.4 0.8 4.3 aerial 5 1.9 2.3 5.8

residential lawns 3.0 lb ai/A ground1 0.3 0.7 3.7 aerial 5 1.7 2.0 5.0 Shallot, onion, corn (sweet, pop, field) 2.0 lb ai/A ground1 0.2 0.4 2.4 aerial 5 1.1 1.3 3.3

Carrot 1.9 lb ai/A ground1 0.2 0.4 2.3 aerial 5 1.1 1.3 3.2

Sunflower 1.73 lb ai/A ground1 0.2 0.4 2.1 aerial 5 1.0 1.2 2.9 Tomato, tomatillo, tobacco, sorghum, potato (white/Irish), lupine (grain), garlic, garbanzos (including chick peas) beans, succulent (snap or lima) beans, dried-type beans, cotton, cowpea (southern pea, black-eyed bean) 1.485 lb ai/A ground1 0.2 0.3 1.8

aerial 5 0.8 1.0 2.5 Wheat, pepper, pepino (melon pear), groundcherry, eggplant, strawberry 1.425 lb ai/A ground 1 0.2 0.3 1.7 aerial 5 0.8 1.0 2.4

Legume vegetables 1.24 lb ai/A ground1 0.1 0.3 1.5 aerial 5 0.7 0.8 2.1Rice, mustard cabbage (gai choy, pakchoi), kohlrabi, cauliflower, cabbage (Chinese), cabbage, brussels sprouts, broccoli (Chinese), broccoli, Brassica (head and stem) vegetables 1.0 lb ai/A ground1 0.1 0.2 1.2

aerial 5 0.6 0.7 1.7 * = LOC exceedances (RQ > 1) are bolded and shaded.

5.1.3 Primary Constituent Elements of Designated Critical Habitat

5.1.3. 1 Aquatic-Phase (Aquatic Breedin g Habitat and Aquatic NonBreeding Habitat)
Three of the four assessment endpoints for the aquatic-phase primary constituent elements (PCEs) of designated critical habitat for the CRLF are related to potential effects to aquatic and/or terrestrial plants:

8 8• Alteration of channel/pond morphology or ge ometry and/or increase in sediment deposition within the stream channel or pond: aquatic habitat (including riparian vegetation) provides for shelter, fora ging, predator avoidance, and aquatic dispersal for juvenile and adult CRLFs.

• Alteration in water chemistry/quality including temperature, turbidity, and oxygen content necessary for normal growth and viability of juvenile and adult CRLFs and their food source.

• Reduction and/or modification of aquatic-b ased food sources for pre-metamorphs ( e.g., algae). Based on the risk estimation for potential eff ects to aquatic and/or terrestrial plants provided in Sections 5.1.1.2, 5.1.1.3, and 5.1.2.3, pendimethalin may affect aquatic-phase PCEs of designated habitat re lated to effects on aquatic and/or terrestrial plants.
The remaining aquatic-phase PCE is “alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source.” To assess the impact of pendimethalin on this PCE ( i.e. , alteration of food sources), acute and chronic freshwater fish and invertebrate toxicity endpoint s, as well as endpoints for aquatic non-vascular plants, are used as meas ures of effects. RQs for these endpoints were calculated in Sections 5.1.1.1 and 5.1.1.2. Based on RQ exceedances of LOC, pendimethalin may affect aquatic-phase PCEs of designated habitat re lated to effects of alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source.

5.1.3.2 Terrestrial-Phase (Upland Habita t and Dispersal Habitat)
The first two assessment endpoints for the terrestrial-phase PCEs of designated critical habitat for the CRLF are related to poten tial effects to terrestrial plants:

• Elimination and/or disturbance of upland ha bitat; ability of hab itat to support food source of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or dripline surroundi ng aquatic and riparian habitat that are comprised of grasslands, woodlands, and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator avoidance

• Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat within designated un its and between occupied locations within 0.7 mi of each other that allow for movement be tween sites including both natural and altered sites which do not cont ain barriers to dispersal
The risk estimation for terrestrial-phase PCEs of designated habitat related to potential effects on terrestrial plants is provided inSection 5.1.2.3. Based on exceedances of LOC for non-target terrestrial plants , all use sites of pendimethalin may affect the first and second terrestrial - phase PCEs.

8 9The third terrestrial-phase PCE is “reducti on and/or modification of food sources for terrestrial phase juveniles and adults.” To assess the impact of pendimethalin on this PCE, acute and chronic toxicity endpoi nts for birds, mammals, and terrestrial invertebrates are used as measures of effects. RQs for thes e endpoints were calculated in Section 5.1.2.3. Based on RQ exceedances of LO C from all use sites, pendimethalin may affect the third terrestrial - phase PCE.
The fourth terrestrial-phase PC is based on alteration of chemi cal characteristics necessary for normal growth and viability of juvenile and adult CRLFs and their food source. Direct acute and chronic RQs for terrestrial-phase CRLFs are presented in Section 5.1.2.1. Based on RQ exceedances of LO C from all use sites, pendimethalin may affect the forth terrestrial - phase PCE.

5.2 Risk Description The risk description synthesizes an overall conclusion regarding th e likelihood of adverse impacts leading to an effects determination ( i.e ., “no effect,” “may affect, but not likely to adversely affect,” or “likely to advers ely affect”) for the CRLF and its designated critical habitat.
Based on the RQs presented in the Risk Es timation (Section 5.1) a preliminary effects determination is “may affect” for the CRLF and critical habitat.

The direct or indirect effect LOCs are exceed ed and effects may modi fy the PCEs of the CRLF’s critical habitat, the Agency conclude s a preliminary “may affect” determination for the FIFRA regulatory action regarding pendimethalin. A summary of the results of the risk estimation results are provided in Error! Not a valid bookmark selfreference. 1 for direct and indirect effects to the CRLF and in Table 5-12 2 for the PCEs of designated critical habitat for the CRLF. Table 5-11 Risk Estimation Summary for Pendimethalin - Direct and Indirect Effects to CRLF

Assessment Endpoint LOC Exceedances (Y/N) Description of Results of Risk Estimation

Aquatic Phase (eggs, larvae, tadpoles, juveniles, and adults) Direct Effects Survival, growth, and reproduction of CRLF individuals via direct effects on aquatic phases Yes There are acute LOC exceedances for fish, the surrogate for the aquatic-phase CRLF.

Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects to food supply ( i.e., freshwater invertebrates, non-vascular plants) Yes There are LOC exceedan ces for non-target aquatic non-vascular plants. There are no acute and chronic LOC exceedances for aquatic invertebrates.

Indirect Effects Survival, growth, and reproduction Yes There are exceedances of the LOC for both vascular and nonvascular aquatic plants.

9 0Assessment Endpoint LOC Exceedances (Y/N) Description of Results of Risk Estimation

of CRLF individuals via effects on habitat, cover, and/or primary productivity ( i.e., aquatic plant community) Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects to riparian vegetation, required to maintain acceptable water quality and habitat in ponds and streams comprising the species’ current range. Yes There are LOC exceedan ces for non-target aquatic vascular and terrestrial plants. Effects are pos sible for riparian vegetation.

Terrestrial Phase (Juveniles and adults) Direct Effects Survival, growth, and reproduction of CRLF individuals via direct effects on terrestrial phase adults and juveniles Yes There are acute and chronic LO C exceedances to birds, the surrogate for the terr estrial-phase CRLF.

Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects on prey ( i.e., terrestrial invertebrates, small terrestrial mammals and terrestrial phase amphibians) Yes There are acute and chronic LO C exceedances to birds, the surrogate for the terres trial-phase amphibians. There are LOC exceedances (>0.05) for terrestrial invertebrates. There are acute and chroni c LOC exceedances for small mammals.

Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects on habitat ( i.e., riparian vegetation) Yes There are LOC exceedan ces for non-target aquatic vascular and terrestrial plants. Effects are possible for riparian vegetation.

Table 5-12 Risk Estimation Summary for Pendimethalin – PCEs of Designated Critical Habitat for the CRLF

Assessment Endpoint Habitat Effects (Y/N) Description of Results of Risk Estimation
Aquatic Phase PCEs (Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat) Alteration of channel/pond morphology or geometry and/or increase in sediment deposition within the stream channel or pond: aquatic habitat (including riparian vegetation) provides for shelter, foraging, predator avoidance, and aquatic dispersal for juvenile and adult CRLFs. Yes There are LOC exceedances for non-target aquatic vascular and terrestrial plan ts. Effects are possible to non-target terrestrial and aquatic vascular plants inhabiting riparian areas.

9 1Assessment Endpoint Habitat Effects (Y/N) Description of Results of Risk Estimation
Alteration in water chemistry/quality including temperature, turbidity, and oxygen content necessary for normal growth and viability of juvenile and adult CRLFs and their food source. Yes There are LOC exceedances for non-target aquatic vascular and terrestrial plants. Alteration in water chemistry/quality is possible due to effects on aquatic/terrestrial plant communities in riparian

areas. Alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source. Yes Due to potential effects on non-target aquatic plants and terrestrial riparian plant species, alteration in chemical characteristics of aquatic habitat ( e.g

. dissolved oxygen) may occur.Reduction and/or modification of aquaticbased food sources for pre-metamorphs (e.g., algae) Yes There are LOC exceedances for non-vascular aquatic plants (i.e. algae).

Terrestrial Phase PCEs (Upland Habitat and Dispersal Habitat) Elimination and/or disturbance of upland habitat; ability of habitat to support food source of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or dripline surrounding aquatic and riparian habitat that are comprised of grasslands, woodlands, and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator avoidance Yes There are LOC exceedances for non-target terrestrial plants.

Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat within designated units and between occupied locations within 0.7 mi of each other that allow for movement between sites including both natural and altered sites which do not contain barriers to dispersal Yes There are LOC exceedances for non-target terrestrial plants. These effects may alter plant communities necessary fo r dispersal habitat.

Reduction and/or modification of food sources for terrestrial phase juveniles and adults Yes Acute and chronic effects are possible on amphibians and mammal that serve as prey for CRLFs

Alteration of chemical characteristics necessary for normal growth and viability of juvenile and adult CRLFs and their food

source. Yes Changes in aquatic vegetation and riparian communities may alter the chemical characteristic of CRLF habitat

Following a “may affect” determination, additio nal information is considered to refine the potential for exposure at th e predicted levels based on th e life history characteristics ( i.e. , habitat range, feedi ng preferences, etc.) of the CRLF. Based on the best available information, the Agency uses the refined ev aluation to distinguish those actions that “may affect, but are not likely to adversely a ffect” from those actions that are “likely to adversely affect” the CRLF and its designated critical habitat.

The criteria used to make determinations thatthe effects of an acti on are “not likely to adversely affect” the CRLF and its designated critical habitat include the following:

9 2• Significance of Effect : Insignificant effects are those that cannot be meaningfully measured, detected, or evaluated in the c ontext of a level of effect where “take” occurs for even a single individual. “T ake” in this context means to harass or harm, defined as the following:

 Harm includes significant habitat modification or degradation that results in death or injury to listed species by significantly impairing behavioral patterns such as br eeding, feeding, or sheltering.

 Harass is defined as actions that create the likelihood of injury to listed species to such an extent as to significantly disrupt normal behavior patterns which include, but are no t limited to, breeding, feeding, or sheltering.

• Likelihood of the Effect Occurring : Discountable effect s are those that are extremely unlikely to occur.

• Adverse Nature of Effect : Effects that are wholly be neficial without any adverse effects are not considered adverse.
A description of the risk and effects determination for each of the established assessment endpoints for the CRLF and its designated critical habitat is provided in Sections 5.2.1 through 5.2.4.

5.2.1 Direct Effects

5.2.1.1 Aquatic-Phase CRLF
The aquatic-phase considers life stages of th e frog that are obligatory aquatic organisms, including eggs and larvae. It also considers submerged te rrestrial-phase juveniles and adults, which spend a portion of their time in water bodies that may receive runoff and spray drift containing pendimethalin.
This assessment used the most sensitive acute and chronic toxicity values across fish species tested since there was no amphibian data available. RQs were based on acute studies in rainbow trout (LC 50= 138 ug/L, MRID 00046291) and a chronic NOAEC in fathead minnow (NOAEC = 6.3 ug/L, MRID 00037940).
The highest acute RQ was 0.12 which exceeds th e Agency’s listed species acute LOC of 0.05. Based on a default probit slope value of 4.5 for the rainbow trout with 95% confidence intervals of 2 to 9, the associated pr obability of an indivi dual effect would be approximately 1 in 5.85E+04.
The most sensitive chronic toxicity value is based on a life cycle study in fathead minnow. The chronic RQ (0.8) was based on a NOAEC of 6.3 ug/L which does not exceed the Agency’s chronic LOC of 1.0. Th e NOAEC is from an acceptable life-cycle fathead minnow study (MRID 00024377). Most sensitive endpoint was reduction in egg production that was observed at LOAEC of 44 ug/L

9 3Eleven aquatic EEC scenarios when compared to the acute toxicity for fish as a surrogate for aquatic-phase CRLF have acute RQs that exceeded the listed species LOC (0.05). None of the use sites has exceeded the chroni c LOC for the CRLF. For the scenarios that exceeded the acute LOC for listed species, the pr obability of individual effect at acute RQ ranges from 1 in 5.85E+04 to 1 in 2.51E+06. The acute and chronic RQs are presented in Section 5.1.1.1. Direct effects to the aquatic-phase CRLF are based on peak EECs in the standard pond and the lowest acutetoxicity value for fr eshwater fish. In order to assess direct chroni c risks to the CRLF, 60-day EECs and the lowest chronic toxicity value for freshwater fish are use d. Based on exceedances of the acute LOC for listed species (0.05), pendimethalin is likely to directly affect the aquatic-phase of the CRLF (LAA).
Incident data provided to the Ag ency indicate that there are two alleged fish kill incidents that involve pendimethalin. However, thes e incidents do not show that pendimethalin registered use contributed to the alleged fish kill incidents. One of the alleged incidents is a spill in which an up to an estimated 300 gallons of undiluted Prowl was spilled into a creek. Another alleged incident involved pendimethalin applied as part of a mixture with Chlorpyrifos, which is highly toxic to fis h. Further information on the pendimethalin incidents are provided in Appendix H.
Monitoring data indicate th at EECs modeled in PRZM-EXA MS are conservative. The highest detected pendimethalin is 0.679 ppb in San Joaquin-Tulare River Basin. The peak EECs range from 16.6 ppb to 6.8 ppb for those scenarios that exceed the listed species acute LOC (0.05).
Based on the acute listed species LOC exceed ances for CRLF and the widespread use sites that exceed the acute listed species LO C, pendimethalin is Likely to Adversely Affect (LAA) the aquatic- phase CRLF directly.

5.2.1.2 Terrestrial-Phase CRLF

Acute and chronic LOCs were exceeded for bird s (surrogate for terrestrial-phase CRLF).
Dose-based acute RQs ranged from 1.25 (6.0 lb ai/A application rate ) to 0.2 (1.0 lb ai/A application rate). Dietary-based acute RQs ranged from 0.2 (6.0 lb ai/A application rate) to <0.1 (less than 2 lb ai/A application rate ). The RQs that exceed the endangered species LOC (0.1) are associated with a probability of an individual effect of approximately 1 in 1.5 to 1.21E+03 based on a default probit slope of 4.5.
Avian chronic RQs ranged from 1.0 (1 lb ai/A) to 5.7 (6.0 lb a i/A). No treatment related effects were observed in the bobwhite quail and the LOAEL is greater than 1410 ppm. The mallard duck study (MRID 44907601) showed the parameter of 14-day survivor bodyweight was reduced at 1410 ppm (LOAEL). The NOAEL for the mallard study is 410 ppm. No other treatment related e ffects were observed. Avian body weight reduction may not necessary be a good parame ter to measure effects to frog due to different physiological and caloric requirements. Therefore it is uncertain as to whether

9 4there is a potential chronic risk to CRLF. Since the chronic LOC is exceeded for birds which are surrogates for CRLF, chronic risk cannot be precluded to CRLF. Therefore, the direct effects determination from chronic effects to CRLF is LAA.
Birds were used as surrogate species for terrestrial phase CRLFs. Terrestrial phase amphibians are poikilotherms, which mean that their body temperature varies with environmental temperature; while birds ar e homeotherms (temperature is regulated, constant, and largely independent of environmental temperatures). As a consequence, the caloric requirements of terrestrial phase am phibians are markedly lower than birds. Therefore, on a daily dietary intake basis, birds consume more food than terrestrial phase amphibians. This can be seen when comparing the caloric requirements for free living iguanid lizards (used in this case as a surrogate for terrestrial phase amphibians) to song birds (U.S. EPA, 1993):
iguanid FMR (kcal/day)= 0.0535 (bw g) 0.799
passerine FMR (kcal/day) = 2.123 (bw g) 0.749
With relatively comparable slopes to the al lometric functions, one can see that, given a comparable body weight, the free living metabol ic rate (FMR) of birds can be 40 times higher than reptiles, though the requiremen t differences narrow with high body weights.
Because the existing risk assessment process is driven by the dietary route of exposure, a finding of safety for birds, with their muchhigher feeding rates and, therefore, higher potential dietary exposure is reasoned to be protective of terrestrialphase amphibians. For this not to be the case, terrestrial phaseamphibians would have to be 40 times more sensitive than birds for the differences in di etary uptake to be negated. However, existing dietary toxicity studies in amphibians are lacking. To quantify the potential differences in food intake between birds and terrestrial phase CRLF, food intake equations for the iguanid lizard replaced the food intake equation in T-REX for bird s, and additional food items of the CRLF were evaluated. These f unctions were encompassed in a model called T-HERPS. T-HERPS is available at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm

. Results of this analysis are pr esented in Table 5.13 (use patt ern (1.0 lb ai/A) with lowest EECs and RQs) through Table 5.16 (use pattern (6.0 lb ai/A) withhighest EECs and RQs).

9 5Table 5-13 Upper Bound Kenaga, Acute Terrestrial Herpetofauna Dose-Based Risk Quotients (1 lbs a.i./acre, 1 application)

Size Class (grams) Adjusted LD50 EECs and RQs Broadleaf

Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Small Herbivore Mammals Small Insectivore

Mammal Small Amphibians

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

1.4 1421.00 5.24 0.00 0.58 0.00 N/A N/A N/A N/A N/A N/A 37 1421.00 5.15 0.00 0.57 0.00 92.77 0.07 5.80 0.00 0.18 0.00 238 1421.00 3.38 0.00 0.38 0.00 14.42 0.01 0.90 0.00 0.12 0.00

Table 5-14 Upper Bound Kenaga, Acute Terrestrial Herpetofauna Dose-Based Risk Quotients (1.24 lbs a.i ./acre, 1 application)

Size Class (grams) Adjusted LD50 EECs and RQs Broadleaf

Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Small Herbivore Mammals Small Insectivore

Mammal Small Amphibians

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

1.4 1421.00 6.50 0.00 0.72 0.00 N/A N/A N/A N/A N/A N/A 37 1421.00 6.39 0.00 0.71 0.00 115.03 0.08 7.19 0.01 0.22 0.00 238 1421.00 4.19 0.00 0.47 0.00 17.88 0.01 1.12 0.00 0.15 0.00

Table 5-15. Upper Bound Kenaga, Acute Terr estrial Herpetofauna Dose-Based Risk Quotients (1.425 lbs a.i ./acre, 1 application)

Size Class (grams) Adjusted LD50 EECs and RQs Broadleaf

Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Small Herbivore Mammals Small Insectivore

Mammal Small Amphibians

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

1.4 1421.00 7.79 0.01 0.87 0.00 N/A N/A N/A N/A N/A N/A 37 1421.00 7.65 0.01 0.85 0.00 137.76 0.10 8.61 0.01 0.27 0.00 238 1421.00 5.02 0.00 0.56 0.00 21.42 0.02 1.34 0.00 0.17 0.00

Table 5-16. Upper Bound Kenaga, Acute Terr estrial Herpetofauna Dose-Based Risk Quotients (6 lbs a.i./Acre, 1 application)

Size Class (grams) Adjusted LD50 EECs and RQs Broadleaf

Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Small Herbivore Mammals Small Insectivore

Mammal Small Amphibians

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

9 61.4 1421.00 31.47 0.02 3.50 0.00 N/A N/A N/A N/A N/A N/A 37 1421.00 30.93 0.02 3.44 0.00 556.59 0.39 34.79 0.02 1.07 0.00 238 1421.00 20.27 0.01 2.25 0.00 86.53 0.06 5.41 0.00 0.70 0.00
These data suggest that diet ary exposures from consumpti on of insects by terrestrial phase CRLFs is likely to result in exposu res that do not exceed LOCs. However, the endangered species LOC was exceeded for larg e terrestrial phase CRLFs that consume small herbivorous mammals in use sites that receive only 1.425 lbs a.i./acre or more of pendimethalin applications. The California mouse is a prey item of the CRLF, and this mouse reportedly eats grasses. However, some assumptions included in the assessment of small mammals as a food item are conservative because the CRLF eats a variety of food items and LOCs were not exceeded for CRLFs that eat insectivorous mammals. The RQs for a 37-gram and a 238-gram CRLF that consumes a small herbivore mammal that recently consumed contaminated s hort grass are found below in Table 5.17.

Table 5-17 RQ Comparisons among Weig ht Class and Applications Rates for CRLF Consuming Small Herbivore Ma mmal That Recently Consumed Contaminated Short Grass Use site application rate CRLF weight class Dose-based RQ for small herbivorous mammals 6.0 37 gram 0.39 6.0 238 gram 0.06 1.425 37 gram 0.10 1.425 238 gram 0.02 1.24 37 gram 0.08 1.24 238 gram 0.01 1.0 37 gram 0.07 1.0 238 gram 0.01
RQs remain above the endangered species LOC for CRLFs that consume herbivorous mammals for all uses except wh ere applications are less th an 1.425 lb ai/A. Refinements incorporating dietary habits of CRLFs did not preclude potential risks for CRLFs that consume herbivorous mammals.

Current assessment methods of potential risks from chronic exposures for birds do not consider food intake levels. Therefore, T-HERPS does not quantify potential effects of reduced food intake of terrestrial phase CRLFs relative to birds for chronic risk assessments. However, chronic RQs would be expected to be reduced by a similar magnitude seen in the acute analysis.
Incident data provided to the Agency indicate that there are two alleged terrestrial incidents in which birds and s quirrels were killed. In both of these incidents there was no chemical analysis for pendimethalin made of the corpses. Therefore, the allegation that pendimethalin was responsible for the deaths of the birds and squirrels was not confirmed but yet pendimethalin can not be precluded.

9 7Acute and chronic LOCs were exceeded for bi rds (as surrogate for CRLF). The available toxicity data suggest that amphibians are le ss sensitive than birds to pendimethalin, and considering factors such as lower food intake of terrestrial phase amphibians relative to birds reduces EECs and RQs, but does not redu ce RQs to levels that are below LOCs. Potential effects to CRLFs that consume herbivorous mammals cannot be precluded. Based on the weight-of-evidence, there is a potential direct impact to the terrestrial-phase of the CRLF based on the avian acute and chro nic toxicity endpoints as a surrogate for terrestrial-phase CRLF. The effects determin ation of likely to adversely affect (LAA) terrestrial-phase CRLF from direct effects is based on acute and chronic listed species LOC exceedances for birds.

5.2.2 Indirect Effects (via Reductions in Prey Base)

5.2.2.1 Algae (non-vascular plants)

As discussed in Section 2.5.3, the diet of CRLF tadpoles is composed primarily of unicellular aquatic plants (i.e., algae and di atoms) and detritus. Because the aquatic nonvascular plant RQs exceed the LOC for 15 out of 25 pendimethalin use sites, pendimethalin is considered likely to indirectly affect the aquatic-phase CRLF via effects on aquatic nonvascular plants.
There were 604 measurements of pendimeth alin in the Sacramento River and San Joaquin-Tulare River basins. There was measurable pendimethalin in 319 of the 604 samples (53% positive). The highest con centration recorded (0.679 ppb) in the San Joaquin-Tulare River Basin. All 9 measurements at this site were positive for pendimethalin, with a range of 0.262 to 0.679 ppb. LOCs that were exceeded have EECs from the modeled PRZM_EXAMS ranging from p eak of 48 ppb (rice model scenario) to 5.6 ppb. EECs that fall below 5.2 ppb did not exceed the LOC for aquatic plants. The lowest LOC exceedance which has a peak EEC of 5.6 also has a 60-day EEC of 0.8 ppb which is similar to the peak monitoring concentration detected in surface water in California.
There are four aquatic non-vascular plant studies submitted to the Agency. The EC 50 results of these studies range from 5.2 ppb to >174 ppb. Three of the four species have similar results. The EC 50data on the species are below:
Species tested EC 50 MRID Source

Green algae ( Selenastrum capricornutum ) 5.4 ppb 42372204
Marine diatom ( Skeletonema costatum ) 5.2 ppb 42372205
Freshwater diatom (Navicula pelliculosa ) 6.7 ppb 42372206
Bluegreen algae ( Anabaena flos-aquae ) >174 ppb 42372207

9 8Based on the Agency’s LOC for aquatic plants being exceeded and that 3 out of 4 species have sensitive EC 50similarities; there is a potential indirect impact to the CRLF from reduction of aquatic food items. The effects determination for the CRLF based on potential reductions in algae is “likely to adversely affect” (LAA).

5.2.2.2 Aquatic Invertebrates
The potential for pendimethalin to elicit i ndirect effects to the CRLF via effects on freshwater invertebrate food items is depende nt on several factor s including: (1) the potential magnitude of effect on freshwater invertebrate individuals and populations; and (2) the number of prey species potentially affected relative to the expected number of species needed to maintain the dietary needs of the CRLF. Together, these data provide a basis to evaluate whether the number of indivi duals within a prey species is likely to be reduced such that it may indirectly affect the CRLF.
There are no aquatic invertebrate’s chroni c (1.0) or acute (0.5) exceedances of LOC found in section 5.1.1.2. There are two scenarios (rice and forestry) in which the RQ lies between the listed species LO C of 0.05 and the acute LOC of 0.5. The probability of individual effect at RQ for RQ of 0.17 is 1 in 3740 and for the listed species of 0.06 is 1 in 5.22E+07. The scenario with an RQ of 0.17 used a conservative scenario (Rice model) which is a direct instan taneous deposition to a water co lumn. It does not take into account runoffs, dilution, or holding patterns befo re releasing into the environment. Thus the EEC may be an overestimation of the amount of pendimethalinconcentration found waters from rice fields that are released into environs. The probability of individual effect at RQ analysis indicates that the chance of adverse effect to the aquatic invertebrate population is not significant.
Other aquatic invertebrate acute toxicity studies were submitted to the Agency. Another waterflea (Daphnia magna ) study tested with a formulati on of 45.6% active ingredient of pendimethalin. This study showed an EC 50of 5.1 ppm formulated product. A submitted crayfish ( Procambarus simulans ) study showed an EC 50greater than 1.0 ppm (1,000 ppb). This study is considered to be suppl emental due to precipitation was seen of concentrations over 1 ppm, the dissolved O 2concentration is less than 40% of saturation, and DMSO was used as a solvent which tends to increase mortalities rather than decrease them. Both studies show that other aquatic invertebrates have orders of magnitude less sensitivity than the Daphnia magna surrogate.
There were 604 measurements of pendimeth alin in the Sacramento River and San Joaquin-Tulare River basins. There was measurable pendimethalin in 319 of the 604 samples (53% positive). The highest con centration recorded (0.679 ppb) in the San Joaquin-Tulare River Basin. All 9 measurements at this site were positive for pendimethalin, with a range of 0.262 to 0.679 ppb which is well below the toxicity level of Daphnia magna EC 50of 280 ppb by three orders of magnitude.

9 9Based on the weight-of-evidence of chroni c and acute LOC not being exceeded for aquatic invertebrates; the pr obit slope analysis showing pr obability of effect being insignificant; and species sensitivity am ong other aquatic invertebrates being less sensitive than the surrogate invertebrate; th e effects determination for the CRLF based on potential reductions in aquatic invertebrates is “not likely to adversely affect” (NLAA).

5.2.2.3 Fish and Aquatic-phase Frogs
In the absence of toxicity data for amphibians, the most sensitive acute and chronic toxicity values across fish sp ecies tested. RQs were based on acute studies in rainbow trout (LC 50= 138 ug/L, MRID 00046291) and a ch ronic NOAEC in fathead minnow (NOAEC = 6.3 ug/L, MRID 00037940).
The highest acute RQ from the rice model was 0.0.35. The acute LOC is 0.5. Based on a default probit slope value of 4.5 for the rainbow trout with 95 % confidence intervals of 2 to 9, the associated probability of an individu al effect would be approximately 1 in 49.8. The scenario with an RQ of 0.12 used a c onservative scenario (Rice model) which is a direct instantaneous deposition to a water colu mn. It does not take into account runoffs, dilution, or holding patterns befo re releasing into the environment. Thus the EEC may be an overestimation of the amount of pendimeth alin concentration found waters from rice fields that are releas ed into environs.
The next highest RQ is 0.12 from a forestry and Christmas tree use sites. The associated probability of an individual effect would be approximately 1 in 5.85E+04. Eleven scenarios have LOCs that are between the acute LOC (0.5) and the listed species LOC (0.05) and their RQs range from 0.12 to 0.05. Th e probability of indivi dual effect at RQ for RQs of 0.17 to 0.05 is 1 in 5.85E+04 to 1 in 4.18E+08. The probability of individual effect at RQ analysis indicates that the chance of adverse effect to the aquatic invertebrate population is not be significant.
The most sensitive chronic toxicity value is based on a life cycle study in fathead minnow. The chronic RQ (0.8) is base d on a NOAEC of 6.3 ug/L from an acceptable life-cycle study (MRID 00024377). Most sens itive endpoint was reduction in egg production that was observed at LOAEC of 44 ug/L.

Based on no acute or chronic exceedances and th e low probability of an individual effect; the effects determination for the CRLF based on potential reductions in fish and other amphibians as food items of the aquatic-phase CRLF is “ notlikely to adversely affect” (NLAA).

5.2.2.4 Terrestrial Invertebrates
When the terrestrial-phase CRLF reaches juveni le and adult stages, its diet is mainly composed of terrestrial invertebrates.

10 0Toxicity data from honey bee study (MRID 00099890) show the LD50 to be greater than 49.8 μg/Bee. No mortalities were observ ed at the highest concentration.
Based upon an average fresh weight per honey bee of 128 milligrams, the LD 50of honey bees (μg /bee) can be multiplied by 7.8 to de termine the ppm toxicity. The toxicity equivalence in ppm would be 388 ppm. According to the Hoerger, Kenaga 5 nomogram modified by Fletcher 6 , the highest EEC exposure from 6 lb ai/A application to large insects would be 90 ppm and to small inse cts would be 810 ppm. The EEC of small insects is about 2X more than the highest dos e tested. The EEC of the largest insect is less than 2X the dose tested. Although there are no mortalities of the honey bee at the highest dose tested and that under the Agency’s guidelines, pendimethalin is considered to be practically non-toxic to honey bee; the honey bee study did not test up to the highest dose that could be expected from 6 lb ai/A directly onto small insects at the site of application.
There is some uncertainty due to the highe st concentration dose tested on the bee was well below the equivalent of 6 lb ai/A maxi mum application. There was no mortality at the highest dose tested, yet it is uncertain if mortality will exist if a higher dose was used in the bee study that would re flect the maximum application rate. Therefore, potential risk can not be precluded to terrestrial invertebrates as a food item. Because potential risk can not be precluded to terrestrial invertebrates as a food item; the effects determination for the CRLF based on potential reductions in terrestrial invertebrates as prey items is “likely to adversely affect” (LAA).

5.2.2.5 Mammals
Terrestrial phase CRLFs consume small mammals. This assessment used a 15-gram herbivorous mammal to determine if there could be a potential reduction in mammal abundance. Acute dose-based RQs for a 15-gram mammal ranged from 0.1 to 0.6 depending on the use pattern. Assuming a pr obit slope of 4.5, the probability of an individual effect would be approximately 1 in 6.9. Assuming that probability of an individual effect provides insi ght into the potential for reduc tions in a local population of small mammals, a probability of 1 in 6.9 (15.9 %) would result in a measurable impact to mammal abundance and would, therefore, constitute a significant effect.
Reproduction RQs ranged from 5.2 to 25.0. The t oxicity endpoint used in the RQs was based on a parental systemic and reproduc tive NOAEL of 25 mg/kg-bw/day. The

5 Hoerger, F. and E.E. Kenaga. 1972. Pesticide residu es on plants: correlation of representative data as a basis for estimation of their magnitude in the environment. IN: F. Coulston and F. Corte, eds., Environmental Quality and Safety: Chemistry, Toxicology and Technology. Vol 1. Georg Theime Publishers, Stuttgart, Germany. pp. 9-28 6 Fletcher, J.S., J.E. Nellesson and T. G. Pfleeger. 1994. Literature re view and evaluation of the EPA foodchain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants. Environ. Tox. and Chem. 13(9):1383-1391

10 1parental systemic endpoint was based on decreased body weight gain and food consumption at the LOAEL of 125 mg/kg/day ( 500 ppm ). The reproductive/offspring NOAEL is 25 mg/kg/day ( 500 ppm ), based on decreases in the number of pups born and pup weight at the LOA EL of 125 mg/kg/day ( 2500 ppm ) which may be a significant population effect. The RQs indicate that potential exposures exceed the NOAEL for all uses. Due to the chronic LOC being exceeded for small mammal prey and the reproductive endpoint is base d on decreasing numbers of pups born and pup weight, the effects determination for the potential for pendimethalin to indirectly affect the CRLF from potential impacts to mammalian preyis likely to adversely affect (LAA).

5.2.2.6 Terrestrial-phase Amphibians
The effects determination for terrestrial phase CRLF consuming small mammalian prey was “likely to adversely affect” (LAA). Th is determination was based solely on frogs that consume potentially contaminated herbiv ore mammals. Terrestrial amphibian prey of the CRLF includes small amphibians such as tree frogs that do not prey on mammals. Therefore, the mammalian food group is not re levant in the evaluation of potential reductions in amphibian prey abundance.
Avian (as surrogate for frog and CRLF) listed species RQs exceeded LOCs (0.1) (Section 5.1). Acute LOCs (0.5) were not exceeded for insectivorous amphibians using the THERPS model (Table 5.16) at th e highest rate of application (6 lb ai/A). Therefore, reductions from acute effects in amphibian prey as a food item at levels likely to affect the CRLF are not likely to occur, and the effects determination for the CRLF based on potential reductions in terrestrial amphibians is “not likely to adversely affect” (NLAA).

Since the chronic LOC have been exceede d, the effects determination for the CRLF based on potential reductions in terrestrial- phase amphibians as food item is “likely to adversely affect” (LAA) from chronic LOC exceedances.

5.2.3 Indirect Effects (via Habitat Effects)

5.2.3.1 Aquatic Plants (Vascular and Non-vascular)
Aquatic plants serve several important functi ons in aquatic ecosystems. Non-vascular aquatic plants are primary producers and pr ovide the autochthonous energy base for aquatic ecosystems. Vascular plants provide structure as attachment sites and refugia for many aquatic invertebrates, fish, and juvenileorganisms, such as fish and frogs. In addition, vascular plants al so provide primary productivity and oxygen to the aquatic ecosystem. Rooted plants help reduce se diment loading and provide stability to nearshore areas and lower streambanks. In a ddition, vascular aquatic plants are important as attachment sites for egg masses of CRLFs.

10 2Potential indirect effects to the CRLF ba sed on impacts to habitat and/or primary production were assessed using RQs from fres hwater aquatic vascul ar and non-vascular plant data. Section 5.2.2.1 indicates that pend imethalin is likely to adversely impact nontarget aquatic plants.
LOCs are exceeded for aquatic vascular plants and algae from exposure to pendimethalin from runoff or spray drift. The non-vascul ar RQs that exceed LOC range from 1.1 to 9.2 and exceed the LOC for 15 out of 25 pendimethalin aquatic model scenarios. The vascular plant LOC is exceeded for 2 of the 25 aquatic model scenarios with the RQs of 1.3 and 3.8.
There were 604 measurements of pendimeth alin in the Sacramento River and San Joaquin-Tulare River basins. There was measurable pendimethalin in 319 of the 604 samples (53% positive). The highest con centration recorded (0.679 ppb) were found in the San Joaquin-Tulare River Ba sin. All 9 measurements at this site were positive for pendimethalin, with a range of 0.262 to 0.679 ppb. LOCs that were exceeded have EECs from the modeled PRZM_EXAMS ranging from p eak of 48 ppb (rice model scenario) to 5.6 ppb. EECs that fall below 5.2 ppb did not exceed the LOC for aquatic nonvascular plants and 12.5 ppb for the a quatic vascular plants.

Potential indirect effects to the CRLF ba sed on impacts to habitat and/or primary production were assessed using RQs from fres hwater aquatic vascul ar and non-vascular plant data. Based on the LOC exceedances, ther e is a potential indirect impact to the aquatic-phase-CRLF from aquatic habitat degr adation. The effects determination for the aquatic-phase CRLF is “likely to adversely affect” (LAA).

5.2.3.2 Terrestrial Plants
Terrestrial plants serve several important habitat-related functions for the CRLF. In addition to providing habitat and cover for invertebrate and vertebrate prey items of the CRLF, terrestrial vegetation also provides sh elter for the CRLF and cover from predators while foraging. Terrestrial plan ts also provide energy to th e terrestrial ecosystem through primary production. Upland vegetation incl uding grassland and woodlands provides cover during dispersal. Riparian vegetation he lps to maintain the integrity of aquatic systems by providing bank and thermal stability, serving as a buffer to filter out sediment, nutrients, and contaminants before they r each the watershed, and serving as an energy

source. The terrestrial non-target plant LOC is exceeded for all use sites. The RQs are variable according to the method of application used (aerial or ground application) and the amount of active ingredient used. Table 5.18 belo w shows the range of RQs from different application methods.

Table 5-18. Range of Risk Quotients fo r Non-Target Terrestrial Plants from Pendimethalin Usage Application Spray Runoff to Low-Lying Runoff to dry

10 3Application Rate Method Drift RQ semi-aquatic areas adjacent areas 6.0 lb ai/A ground 6.0 66.0 12.0 4.0 lb ai/A ground 4.0 44.0 8.0 3.5 lb ai/A ground 3.5 38.5 7.0 2.0 lb ai/A ground 2.0 22.0 4.0 1.485 lb ai/A ground 1.5 16.3 3.0

1.0 lb ai/A ground 1.0 11.0 2.0 4.0 lb ai/A aerial 20.0 60.0 24.0 3.5 lb ai/A aerial 17.5 52.5 21.0 2.0 lb ai/A aerial 10.0 30.0 12.0 1.485 lb ai/A aerial 7.4 22.3 8.9

1.0 lb ai/A aerial 5.0 15.0 6.0 Bold denotes that the RQ has exceeded the LOC

. Although the endpoint used for runoff (seedling emergence) is 3X more sensitive than the spray drift toxicity endpoint (vegetative vigor), there is more LOC exceedances from aerial application than from runoff. This is due to the fate characteristics of pendimethalin. Pendimethalin binds more clos ely to the soil and is usually carried with soil during a runoff event rath er than with water.
The most sensitive monocot appears to be moresensitive than the most sensitive dicot tested by an order of magnitude. Differen ces of responses between the dicots and monocots are mixed and do overlap. Overall, monocots and dicots are both sensitive to pendimethalin. The herbicidal mode of acti on of pendimethalin is that it disrupts the process of mitosis in the grow th of shoots and roots. It acts as a microtubule disruptor by inhibiting cell division and cell elongation in plants. Absorp tion of the chemical into plant is via roots and shoots.
Based on the weight-of-evidence, the Agency co ncludes that there is a potential indirect impact to CRLF by terrestrial habitat degr adation from pendimethalin exposure and therefore pendimethalin is Likely to Advers ely Affect (LAA) the CRLF both riparian and upland vegetation.
If aerial application was to be eliminated at least 1000 feet of CRLF habitat, potential risk would be reduced.

5.2.4 Effects to Designated Critical Habitat
Risk conclusions for the designated critical habitat are the same as those for indirect effects. Agency concludes that there is a potential indirect impact to CRLF by terrestrial and aquatic habitat degradation fr om pendimethalin exposure.

5.2.4.1 Aquatic-Phase PCEs

10 4Three of the four assessment endpoints for the aquatic-phase primary constituent elements (PCEs) of designated critical habitat for the CRLF are related to potential effects to aquatic and/or terrestrial plants:

• Alteration of channel/pond morphology or ge ometry and/or increase in sediment deposition within the stream channel or pond: aquatic habitat (including riparian vegetation) provides for shelter, fora ging, predator avoidance, and aquatic dispersal for juvenile and adult CRLFs.

• Alteration in water chemistry/quality including temperature, turbidity, and oxygen content necessary for normal growth and viability of juvenile and adult CRLFs and their food source.

• Reduction and/or modification of aquatic-b ased food sources for pre-metamorphs ( e.g., algae). Conclusions for potential indire ct effects to the CRLF via di rect effects to aquatic and terrestrial plants are used to determine whether modification to critical habitat may occur. There is a potential for hab itat effects via impacts to a quatic plants (Sections 5.2.2.1 and 5.2.3.1) and terrestrial plants (5.2.3.2)
The remaining aquatic-phase PCE is “alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source.” Other than impacts to algae as food items for tadpoles (discussed above), this PCE is assessed by considering direct and indirect effects to the aquatic-phase CRLF via acute and chronic freshwater fish and invertebrate toxicity e ndpoints as measures of effects. There is a potential for habitat effects via impacts to aquatic-phase CRLFs (Sections 5.2.1.1) and effects to freshwater invertebrates and fi sh as food items (Sections 5.2.2.2 and 5.2.2.3).

5.2.4.2 Terrestrial-Phase PCEs
Two of the four assessment endpoints for the terrestrial-phase PCEs of designated critical habitat for the CRLF are related to poten tial effects to terrestrial plants:

• Elimination and/or disturbance of upland ha bitat; ability of hab itat to support food source of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or drip line surr ounding aquatic and riparian habitat that are comprised of grasslands, woodlands, and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator avoidance.

• Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat within designated un its and between occupied locations within 0.7 mi of each other that allow for movement be tween sites including both natural and altered sites which do not cont ain barriers to dispersal.
There is a potential for habitat effects vi a impacts to terrestri al plants (5.2.3.2).

10 5The third terrestrial-phase PCE is “reducti on and/or modification of food sources for terrestrial phase juveniles and adults.” To assess the impact of pendimethalin on this PCE, acute and chronic toxic ity endpoints for terrestrial invertebrates, mammals, and terrestrial-phase frogs are used as measures of effects. There is a potential for habitat effects via indirect effects to terrestrial-pha se CRLFs via reduction in prey base (Section 5.2.2.4 for terrestrial invertebrates, Section 5.2.2.5 for mammals, and 5.2.2.6 for frogs).
The fourth terrestrial-phase PCE is based on alteration of chemical characteristics necessary for normal growth and viability of juvenile and adult CRLFs and their food source. There is a potential for habitat modification via direct (Section 5.2.1.2) and indirect effects (Sections 5.2.2.4, 5.2.2.5, and 5.2.2.6) to terrestrial-phase CRLFs.

5.2.5 Spatial Extent of Potential Effects
An LAA effects determination applies to those areas where it is expected that the pesticide’s use will directly or indirectly affect the CRLF or its designated critical habitat. To determine this area, the footprint of pe ndimethalin’s use pattern is identified, using land cover data that correspond to pendimethalin’s use pattern. The spatial extent of the effects determination also includes areas beyond the initial area of concern that may be impacted by runoff and/or spray drift. The identified direct/indi rect effects and/or modification to critical habitat are anticipatedto occur only for thos e currently occupied core habitat areas, CNDDB occurrence sections, and designate d critical habitat for the CRLF that overlap with the initial area of concern plus at least 1000 feet from its boundary. It is assumed that non-flowing waterbodies (or potential CRLF habitat) are included within this area.
In addition to the spray drift buffer, the resu lts of the downstream dilution extent analysis result in a distance of 272 kilometers which represents the maximum continuous distance of downstream dilution from the edge of the in itial area of concern (based on the forestry use; see Appendix D). If any of these stream s reaches flow into CRLF habitat, there is potential to affect either th e CRLF or modify its habitat. These lotic aquatic habitats within the CRLF core areas and critical hab itats potentially contai n concentrations of pendimethalin sufficient to result in LAA determination or effects to critical habitat.
The determination of the buffer distance and downstream dilution for spatial extent of the effects determination is described below.

5.2.5.1 Spray Drift
In order to determine terrestrial and aquati c habitats of concern due to pendimethalin exposures through spray drift, it is necessary to estimat e the distance that spray applications can drift from the treated area and still be present at concentrations that exceed levels of concern. An analysis of spray drift distances was completed using the AgDrift model.

10 6In order to characterize the spatial extent of the effects determination that is relevant to the CRLF (i.e. NLAA versus LAA), an analys is was conducted using the most sensitive non-endangered plant EC 25 of 0.01 lbs ai/acre (ryegrass s eedling emergence). Typically the NOAEC is used when there is an oblig ate relationship between the species being assessed and endangered plants (or other taxa). However, there is no obligate relationship between the CRLF and any endangered plant; therefore the LAA/NLAA determination is based on the area de fined by the non-listed species LOC (i.e., EEC/EC 50 ).
The most sensitive effect of concern was the lowest EC25 for seedling emergence, 0.01 lb/acre for ryegrass. Tier 1 ground spray anal ysis (terrestrial assessment) was performed with the AgDrift model. The following setti ngs were used: High boo m, ASAE very fine to fine spray, point deposition, and an application rate of 6 lb/acre. The resulting buffer distance for ground spray was 899 feet.
A similar analysis was performed using AgDrift, using the Tier 1 aerial (terrestrial) assessment with ASAE very fine to fine sp ray, point deposition, and an application rate of 4 lb/acre. The resulting buffer exceeds the limit of the AgDrift model (approximately 1000 feet). A Tier 2 AgDrift aerial analysis was also conducted, with the same result (over 1000 feet). A summary of the modeled di stances by application rate is presented in Table 5.19.

Table 5-19 Summary of AgDrift Predicted Terrestrial Spray Drift Distances Application Rate (method) Uses Represented EC 25 Distance (ft) 6.0 (ground) 899 4.0 (aerial) Over 1000
Given that the greatest buffer distance is 1,000 feet for terrestrial plants, this value was used to define the spatial extent of the eff ects determination (i.e., this buffer distance is added to the initial area of concern).
Similar to the analysis descri bed above, the buffer distance needed to get below the most sensitive aquatic LOC was determined. This distance identifies those locations where water bodies can be impacted by spray drift deposition alone (no runoff considered) resulting in concentrations above the LOC. The most sensitive aquatic endpoint is for aquatic non-vascular plants ( Skeletonema ) with an EC 50 value of 5.2 μg/L. The analysis yields a much lower ground-spray buffer di stance than the terrestrial buffer with a distance of 79 feet (based on the non-listed LOC using the EC 50value). However, the Tier 1 and 2 aerial analysis again yields a di stance of over 1,000 feet. The results of the analysis are presented in Table 5.20.

Table 5-20 Summary of AgDrift P redicted Aquatic Spray Drift Distances Application Rate (method) Uses Represented EC 50 Distance (ft)

10 7Application Rate (method) Uses Represented EC 50 Distance (ft) 6.0 (ground) 79 4.0 (aerial) Over 1000

5.2.5.2 Downstream Dilution Analysis
The downstream extent of exposure in streams and rivers is where the EEC could potentially be above levels that would exceed the most sensitive LOC. To complete this assessment, the greatest ratio of aquatic RQto LOC was estimated. Using an assumption of uniform runoff across the landscape, it is assumed that streams flowing through treated areas (i.e. the initial area of concern) are represente d by the modeled EECs; as those waters move downstream, it is assumed that the influx of non-impacted water will dilute the concentrations of pe ndimethalin present.
Using an EC 50value of 5.2 ug/L for non-vascular a quatic plants (the most sensitive species is Skeletonema costatum ) and a maximum peak EEC for applications to rice of 48 ug/L yields an RQ/LOC ratio of 9.2 (9.2/1), which is appl ied to the pasture/hay and cultivated crop land cover clas s. RQ/LOC ratios for other use categories range from 2.3 to 3.2. Using the downstream dilution appr oach (described in more detail in Appendix D ) yields a target percent crop area (PCA) of 11% for the ratio of 9.2. This value has been input into the downstream dilution ap proach and results in a distance of 47 kilometers. However, the forestry RQ/LOC ratio of 3.2 yields a downstream dilution distance of 272 kilometers, which represen ts the maximum continuous distance of downstream dilution from the edge of the initial area of concern, for the forestry land cover class. Similar to the spray drift buffer described above, the LAA/NLAA determination is based on the area defined by the point where concentrations exceed the EC 50value.

5.2.5. 3 Overlap between CRLF habitat and Spatial Extent of Potential Effects

An LAA effects determination is made to those areas where it is expected that the pesticide’s use will directly or indirectly affect the CRLF or its designated critical habitat and the area overlaps with the core areas, critical habitat and available occurrence data for CRLF.
For pendimethalin, the use patterns fall in to the following land cover classes: Cultivated Crops; Developed, High Intensity; Developed, Low Intensity; Developed, Medium Intensity; Developed, Open Space; Forest; Open Water; Orchards and vineyards; Pasture/Hay; Wetlands; Turf; and Rights-of-way. The overlap area also includes areas beyond the initial area of concern that may be impacted by runoff and/or spray drift, where it overlaps with CRLF habitat. Appendix D provides maps of the initial area of concern, along with CRLF habitat areas, including curre ntly occupied core

10 8areas, CNDDB occurrence sections, and designated critical habitat. Itis expected that any additional areas of CRLF habitat that ar e located at least 1 000 ft (to account for offsite migration via spray drift) and 272 kilometers of stream reach (to account for downstream dilution) outside the initial area of concern may also be impacted and are part of the full spatial extent of the LAA and effects to critical habitat determination.

10 9Figure 2.6. Overlap Map: CRLF Habitat and Pendimethalin Initial Area of Concern

11 0In order to confirm that uses of pendimeth alin have the potential to affect CRLF through direct applications to targetareas and runoff and spray drift to non-target areas, it is necessary to determine whether or not the sp atial extent of potential effects based on agricultural and orchard crops and turf use of pendimethalin overlap with CRLF habitats. Spatial analysis using ArcGIS 9.1 indicates that lotic aquatic habitats within the CRLF core areas and critical habitats potentially contain concentrations of pendimethalin sufficient to result in RQ values that exceedLOCs. In addition, terrestrial habitats (and potentially lentic aquatic habitats) of the final action areas for agricultural, forestry, rights-of ways, ornamental, and turf uses of pendimethalin overlap with the core areas, critical habitat and available occurrence data for CRLF ( Figure 2.6 ). Thus, uses of pendimethalin on agricultural and orchard crops and turf use could resu lt in exposures of the CRLF to pendimethalin in a quatic and terrestrial habitats.

6.0 Uncertainties

6.1 Exposure Assessment Uncertainties

6.1.1 Maximum Use Scenario
The screening-level risk assessment focuses on characterizing poten tial ecological risks resulting from a maximum use scenario, which is determined from labeled statements of maximum application rate and number of appli cations with the shortest time interval between applications. The frequency at whic h actual uses approach this maximum use scenario may be dependant on pest resistance, timing of applications, cultural practices, and market forces.

6.1.2 Aquatic Exposure Modeling of Pendimethalin
The standard ecological water body scenario (EXAMS pond) used to calculate potential aquatic exposure to pesticides is intended to represent conservative estimates, and to avoid underestimations of the actual exposure. The standard scenario consists of application to a 10-hectare field bordering a 1-hectare, 2-meter deep (20,000 m 3 ) pond with no outlet. Exposure estimates generated using the EXAMS pond are intended to represent a wide variety of vulnerable water bodies that occur at the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, man-made and natural ponds, and intermittent and lower order streams. As a group, there are factors that make these water bodies more or less vulnerablethan the EXAMS pond. Static water bodies that have larger ratios of pesticide-treate d drainage area to water body volume would be expected to have higher peak EECs than the EXAMS pond. These water bodies will be either smaller in size or have larger drainage areas. Sm aller water bodies have limited storage capacity and thus may overflow and carrypesticide in the discharge, whereas the EXAMS pond has no discharge. As waters hed size increases beyond 10-hectares, it becomes increasingly unlikely that the entire watershed is planted w ith a single crop that is all treated simultaneously with the pesticid e. Headwater streams can also have peak concentrations higher than the EXAMS pond, but they likely persist for only short periods of time and are then car ried and dissipated downstream.

11 1The Agency acknowledges that there are so me unique aquatic habitats that are not accurately captured by this modeling scenario and modeling results may, therefore, under- or over-estimate exposure, depending on a number of variables. For example, aquatic-phase CRLFs may inhabit water bodies of different size and depth and/or are located adjacent to larger orsmaller drainage areas thanthe EXAMS pond. The Agency does not currently have sufficient information regarding the hydrology of these aquatic habitats to develop a specific alternate scenario for the CRLF. CRLFs prefer habitat with perennial (present year-round) or near-perennial water and do not frequently inhabit vernal (temporary) pools because conditions inthese habitats are generally not suitable (Hayes and Jennings 1988). Therefore, the EXAMS pond is assumed to be representative of exposure to aquatic-phase CRLFs. In addi tion, the Services agree that the existing EXAMS pond represents the best currently available approach for estimating aquatic exposure to pesticid es (USFWS/NMFS 2004).
In general, the linked PRZM/EXAMS model produces estimated aquatic concentrations that are expected to be exceeded once within a ten-year period. The Pesticide Root Zone Model is a process or “simulation” model that calculates what happens to a pesticide in an agricultural field on a day-to-day basis. It considers factors such as rainfall and plant transpiration of water, as well as how and whenthe pesticide is applied. It has two major components: hydrology and chemical transport. Water movement is simulated by the use of generalized soil parameters, including fi eld capacity, wilting point, and saturation water content. The chemical transport com ponent can simulate pesticide application on the soil or on the plant foliage. Dissolved, adsorbed, and vapor-phase concentrations in the soil are estimated by simultaneously cons idering the processes of pesticide uptake by plants, surface runoff, erosion, decay, volatilization, foliar wash-off, advection, dispersion, and retardation.

Uncertainties associated with each of thes e individual components add to the overall uncertainty of the modeled concentrations . Additionally, model inputs from the environmental fate degradation studies are chosen to represent the upper confidence bound on the mean values that are not expected to be exceeded in the environment approximately 90 percent of the time. M obility input values are chosen to be representative of conditions in the environment. The natural variation in soils adds to the uncertainty of modeled values. Factors suchas application date, crop emergence date, and canopy cover can also affect estimated c oncentrations, adding to the uncertainty of modeled values. Factors within the ambien t environment such as soil temperatures, sunlight intensity, antecedent soil moistu re, and surface water temperatures can cause actual aquatic concentrations to differ for the modeled values.
Unlike spray drift, tools are currently not av ailable to evaluate th e effectiveness of a vegetative setback on runoff and loadings. Th e effectiveness of vegetative setbacks is highly dependent on the condition of the vegetative strip. For example, a wellestablished, healthy vegetativesetback can be a very eff ective means of reducing runoff and erosion from agricultural fields. Alternatively, a setbac k of poor vegetative quality or a setback that is channelized can be ine ffective at reducing loadings. Until such time

11 2as a quantitative method to estimate the effect of vegetative setbacks on various conditions on pesticide loadings becomes available, the aquatic exposure predictions are likely to overestimate exposure where h ealthy vegetative setbacks exist and underestimate exposure where poorly developed, channelized, or bare setbacks exist.

In order to account for uncertainties associ ated with modeling, available monitoring data were compared to PRZM/EXAMS estimates of peak EECs for the different uses. As discussed above, several data values were available from NAWQA for pendimethalin concentrations measured in surface waters receiving runoff from agricultural areas. The specific use patterns (e.g. application rates and timing, crops) associated with the agricultural areas are unknown, however, they are assumed to be representative of potential pendimethalin use areas.
The monitoring data available are within same order of magnitude as the PRZM-EXAMS predictions, or slightly lower, for the agricu ltural and forestry scenarios. The monitoring data indicated that the maximum observed concentration in Sacramento River valley streams was 0.7 ppb, and in San Joaquin Valley streams it was 3.5 ppb. PRZM-EXAMS prediction (not including the scenarios for im pervious surfaces) estimated pendimethalin to be in the surface waters at peak con centrations from 3 to 16 ppb. The impervious scenario was much higher at 143 ppb.

6.1.3 Usage Uncertainties
County-level usage data were obtained from California’s Department of Pesticide Regulation Pesticide Use Reporti ng (CDPR PUR) database. Th irteen years of data (1994

–2006) were included in this analysis. B ecause statistical methodology for identifying outliers, in terms of area treated and pounds applied, was not provided by CDPR for years before 2002, these data are less accurate. No methodology for removing outliers was provided by CDPR for 2001 and earlier pes ticide data; therefore, this information was included separately in the analysis becauseit may misrepresent actual usage patterns. CDPR PUR documentation indicate s that errors in the data may include the following: a misplaced decimal; incorrect measures, area treated, or units; and reports of diluted pesticide concentrations. In addition, it is possible that the data may contain reports for pesticide uses that have been cancelled. The CPDR PUR data does not include home owner applied pesticides; therefore, residential uses are not likely to be reported. As with all pesticide usage data, there may be instances of misuse and misreporting. The Agency made use of the most current, verifiable information; in cases where there were discrepancies, the most conservative information was used.

6.1.4 Terrestrial Exposure Modeling of Pendimethalin
The Agency relies on the work of Fletcher et al. (1994) for setting the assumed pesticide residues in wildlife dietary it ems. These residue assumptions are believed to reflect a realistic upper-bound residue estimate, although the degree to which this assumption reflects a specific percentile estimate is difficult to quantify. It is important to note that the field measurement efforts used to devel op the Fletcher estimates of exposure involve

11 3highly varied sampling techniques. It is entirely possible that much of these data reflect residues averaged over entire above ground plan ts in the case of grass and forage sampling.
It was assumed that ingestion of food items in the field occurs at rates commensurate with those in the laborato ry. Although the screening a ssessment process adjusts dryweight estimates of food intake to reflect the increased mass in fresh-weight wildlife food intake estimates, it does not allow for gross energy differences. Direct comparison of a laboratory dietary concentrati on- based effects threshold to a fresh-weight pesticide residue estimate would result in an underestimation of field exposure by food consumption by a factor of 1.25 – 2.5 for most food items.
Differences in assimilative efficiency betw een laboratory and wilddiets suggest that current screening assessment me thods do not account for a potentially important aspect of food requirements. Depending upon species and dietary matrix, bird assimilation of wild diet energy ranges from 23 – 80%, and mamm al’s assimilation ranges from 41 – 85% (U.S. Environmental Protection Agency, 1993). If it is assumed that laboratory chow is formulated to maximize assimilative efficien cy (e.g., a value of 85%), a potential for underestimation of exposure may exist by assu ming that consumption of food in the wild is comparable with consumption during laboratory testing. In th e screening process, exposure may be underestimated because me tabolic rates are not related to food consumption.
For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal was assumed to occupy either the treated field or adjacent areas receiving a treatment rate on the field. Actual habitat requirements of any particular terrestrial species were not considered, and it was assumed that species occupy, exclusively and permanently, the modeled treatment area. Spray drift model predictions sugges t that this assumption leads to an overestimation of exposure to species that do not occupy the treated field exclusively and permanently.

6.1.5 Spray Drift Modeling
Although there may be multiple pendimethalin app lications at a single site, it is unlikely that the same organism would be exposed to the maximum amount of spray drift from every application made. In order for an or ganism to receive the maximum concentration of pendimethalin from multiple applications , each application of pendimethalin would have to occur under identical atmospheric conditions ( e.g. , same wind speed and – for plants – same wind direction) and (if it is an animal) th e animal being exposed would have to be present directly downwind at the same distance after each application. Although there may be sites where the dominant wind direction is fairly consistent (at least during the relatively quiescent conditions that are most favorable for aerial spray applications), it is neverthe less highly unlikely that plants in any specific area would receive the maximum amount of spray drift repe atedly. It appears that in most areas (based upon available meteorological data) wind direction is temporally very changeable, even within the same day. Additionally, other factors, including variations in

11 4topography, cover, and meteorological conditio ns over the transport distance are not accounted for by the AgDRIFT/AGDISP model ( i.e ., it models spray drift from aerial and ground applications in a flat area with little to no ground cover and a steady, constant wind speed and direction). Therefore, in most cases, the drift estimates from AgDRIFT/AGDISP may overestimate exposure evenfrom single applications, especially as the distance increases from the site of application, since the mode l does not account for potential obstructions ( e.g ., large hills, berms, buildings, trees, etc .). Furthermore, conservative assumptions are often made regarding the droplet size distributions being modeled (‘ASAE Very Fine to Fine’ for orchard uses and ‘ASAE Very Fine’ for agricultural uses), th e application method ( e .g., aerial), release hei ghts and wind speeds. Alterations in any of these inputs would change the area of potential effect.

6.1.6 Volatility
Pendimethalin is a semi-volatile compound that may be lost from moist soil. The volatilization half-life fro m moist soil was found to be 12.5 days (MRID 00153766). Pendimethalin has been observed in rainwate r in California (Vogel et al., 2008). This effect was accounted for in the PRZM-EXAMS modeling by invoking the PRZM volatilization routine, thus allowing voltilization to co mpete with runoff and metabolism as a dissipation route. Comparison of the hi ghest EEC scenario (forestry) shows that the effect is small (16.6 ppb with volatility invoked and 18.1 ppb without). The relatively slow volatilization rate from even moist soil is not believed to result in as large or immediate an aquatic exposure as spray drif t at the time of application. Terrestrial exposure of plants and animals is accountedfor at least in part by the AgDrift and AgDISP effect area analysis.

6.1.7 Bioaccumulation
Pendimethalin is believed to be bioaccumulative, as it has a logKow of 5.18, and a whole-body BCF of 5100x in bluegill sunfish (MRID 00156726). PRZM-EXAMS modeling indicates that pendimethalin may accu mulate in sediments as well. Thus, foodchain exposure via accumulation in aquatic organisms may be a completed exposure pathway. However, several factors indicate that such exposure may not be a concern. First, additional bioaccumulation data in catfish (approximate BCF = 1600x), guppies (no accumulation, with metabolism) (MRID 00046293) and crayfish (MRID 00071124) whole body BCF = 1.5x) indicate that bioaccumul ation is not the only response of aquatic organisms to pendimethalin. Second, the bluegill sunfish exposed to pendimethalin accumulated 15 ppm body burden with no ill effects, followed by depuration.
KABAM modeling (Appendix K) indicated some marginal chronic risk for large river otters (chronic dose-based RQ 1.3, but dietary-based RQ 0.169) and marginal acute risk for small CRLF (acute dose-based RQ 0.14 to 0.38, but dietary-based RQ 0.007 to 0.008. However, the assumption of no metabolism in aquatic organisms is probably incorrect, so the results from KABAM showing marginalrisks are therefore discountable.

11 56.2 Effects Assessment Uncertainties

6.2.1 Age Class and Sensitivity of Effects Thresholds
It is generally recognized that test organism age may have a significant impact on the observed sensitivity to a toxicant. The acutetoxicity data for fish are collected on juvenile fish between 0.1 and 5 grams. Aquatic invertebrate acute testing is performed on recommended immature age classes (e.g., first instar for daphnids, second instar for amphipods, stoneflies, mayflies, and third instar for midges).
Testing of juveniles may overe stimate toxicity at older age classes for pesticide active ingredients that act directly without me tabolic transformation because younger age classes may not have the enzymatic systems a ssociated with detoxifying xenobiotics. In so far as the available toxicity data may provide ranges of sensitivity information with respect to age class, this assessment uses th e most sensitive life-stage information as measures of effect for surrogate aquatic animals, and is therefore, considered as protective of the CRLF.

6.2.2 Use of Surrogate Species Effects Data
Guideline toxicity tests and open literature data on pendimethalin are not available for frogs or any other aquatic-phase amphibian; therefore, freshwater fish are used as surrogate species for aquatic-phase amphi bians. Therefore, endpoints based on freshwater fish ecotoxicity data are assumed to be protective of potential direct effects to aquatic-phase amphibians including the CRLF, and extrapolation of the risk conclusions from the most sensitive tested species to the aquatic-phase CRLF is likely to overestimate the potential risks to those species. Efforts ar e made to select the organisms most likely to be affected by the type of compound and us age pattern; however, there is an inherent uncertainty in extrapolating across phyla. In addition, the Agency’s LOCs are intentionally set very low, and conservative estimates are madein the screening level risk assessment to account fo r these uncertainties.

6.2.3 Sublethal Effects
When assessing acute risk, the screening risk assessment relies on the acute mortality endpoint as well as a suite of sublethal respon ses to the pesticide, as determined by the testing of species response to chronic expos ure conditions and subsequent chronic risk assessment. Consideration of additional sublethal data in the effects determination t is exercised on a case-by-case basis and only after careful consideration of the nature of the sublethal effect measured and the extent and quality of available data to support establishing a plausible relationship between the measure of effect (sublethal endpoint)

11 6and the assessment endpoints. However, the fu ll suite of sublethal effects from valid open literature studies is considered for the purposes of defining the action area.

To the extent to which sublethal effects are not considered in this assessment, the potential direct and indirect effects of pendimethalin on CRLF may be underestimated.

6.2.4 Location of Wildlife Species
For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal was assumed to occupy either the treated field or adjacent areas receiving a treatment rate on the field. Actual habitat requirements of any particular terrestrial species were not considered, and it was assumed that species occupy, exclusively and permanently, the modeled treatment area. Spray drift model predictions sugges t that this assumption leads to an overestimation of exposure to species that do not occupy the treated field exclusively and permanently.

6.2.5 Toxicity to Honeybees.
Pendimethalin is rated as practically non-toxic to honeybees. The honeybee contact toxicity data is used as a su rrogate assessment endpoint for al l terrestrial invertebrates. Because the calculated exposure (TREX EEC fo r large and small insects) exceeds the highest tested dose, even though there were no mortalities at the highest dose, there is some residual uncertainty about potential effects to terrestrial inverteb rates. This results in a May Affect determination, however, it is considered discountable.

7.0 Risk Conclusions In fulfilling its obligations under Section 7(a)(2) of the Endangered Species Act, the information presented in this endangered specie s risk assessment represents the best data currently available to assess the potential ri sks of pendimethalin to the CRLF and its designated critical habitat.
Based on the best available information, the Agency makes a Likely to Adversely Affect/May Affect, determination for the CRLF from the use of pendimethalin. The Agency has determined that there is the potential for effects to CRLF designated critical habitat from the use of the chemical. All of the uses might affect the frog or its critical habitat. The LAA determination is from direct and indirect effects to CRLF from the use of pendimethalin. Given the LAA determination for the CRLF and potential effects to designated critical habitat, a description of the baseline status and cumulative effects for the CRLF is provided in Attachment 2.
The LAA effects determination applies to those areas where it is expected that the pesticide’s use will directly or indirectly affect the CRLF or its designated critical habitat. To determine this area, the footprint of pe ndimethalin’s use pattern is identified, using land cover data that correspond to pendimethalin’s use pattern. The spatial extent of the

11 7LAA effects determination also includes area s beyond the initial area of concern that may be impacted by runoff and/or spray drift. Th e identified direct and indirect effects and modification to critical habitat are anticipatedto occur only for thos e currently occupied core habitat areas, CNDDB occurrence sections, and designate d critical habitat for the CRLF that overlap with the initial area of concern plus at least 1000 feet from its boundary (refer to analysis in Section 5.1.4). It is assumed that non-flowing waterbodies (or potential CRLF habitat) are included within this area.
In addition to the spray drift buffer, the resu lts of the downstream dilution extent analysis result in a distance of 272 kilometers which represents the maximum continuous distance of downstream dilution from the edge of the in itial area of concern (refer to analysis in Section 5.1.4). If any of these streams reaches flow into CRLF habitat, there is potential to affect either the CRLF or affect its habitat. These lotic aquatic habitats within the CRLF core areas and critical habitats potential ly contain concentrations of pendimethalin sufficient to result in LAA determinati on or effects to critical habitat.
Appendix K provides maps of the initial area of concern, along with CRLF habitat areas, including currently occupied core areas, CNDDB occurrence sections, and designated critical habitat. It is expected that any a dditional areas of CRLF hab itat that are located at least 1000 ft (to account for offsite migrati on via spray drift) and 272 kilometers of stream distance (to account for downstream dilu tion) outside the initial area of concern may also be impacted and are part of the full spatial extent of the LAA and critical habitat effects determination.
A summary of the risk conclusions and e ffects determinations for the CRLF and its critical habitat, given the uncertainties discussed in Section 6, is presented in Table 7.0-1 and Table 7-2.

Table 7-1 Effects Determination Summa ry for Pendimethalin Use and the CRLF Assessment

Endpoint Effects Determination 1 Basis for Determination
Survival, growth, Potential for Direct Effects and/or reproduction of CRLF individuals LAA 1 Aquatic-phase (Eggs, Larvae, and Adults) : Acute LOCs were exceeded for fish or aquatic-phase amphibians Terrestrial-phase (Juveniles and Adults) : Acute and chronic LOCs were exceeded for birds. The available toxicity data suggest that amphibians are less sensitive than birds to pendimethalin, and considering factors such as lowe r food intake of terrestrial phase amphibians relative to birds reduces EECs and RQs, but does not reduce RQs to levels that are below LOCs. Likely to adversely affect CRLF. Potential for Indirect Effects Aquatic prey items, aquatic habitat, cover and/or primary productivity: LOC is exceeded only for non-vascular aquatic plants. RQs are below LOC for freshwater invertebrates (chronic an d acute effects) and fish or frogs (chronic and acute effects). Pendimethalin could potentially impact terrestrial and aquatic plants to an exte nt that could result in indirect effects to the CRLF or modification of critical habitat. Terrestrial prey items, riparian habitat:

11 8Assessment Endpoint Effects Determination 1 Basis for Determination
Chronic LOC is exceeded for mammal and birds (surrogate for frog). Pendimethalin is practically non-toxic to honeybees with no mortalities observed in testing. LOC is exceeded for terrestrial invertebrates. Uncertainty in toxicity to insects from EEC that is above hi ghest bee concentration tested does not preclude potential risk. Pendimethalin may adversely affect insects. Acute LOCs were not exceeded for insectivorous amphibians using the T-HERPS model at the highest rate of application. LOC is exceeded for non-target terrestri al plants and thereby critical habitat could be affected as a result of these potential impacts. 1 No effect (NE); May affect, but not likely to adversely affect (NLAA) ; May affect, likely to adversely affect (LAA)

Table 7-2 Effects Determination Summary for Pendimethalin Use and CRLF Critical Habitat Impact Analysis Assessment

Endpoint Effects Determination Basis for Determination

Modification of aquatic-phase PCE

Habitat Effects Effects to riparian vegetation (terrestrial plants) and aquatic non-vascular and vascular plants result in LOC exceedances. These effects may indirectly affect the CRLF via reduction in food supply, changes in available cover, physical parameters of the waterbody (e.g. increase temperature or turbidity) LOC is exceeded for effects to non-vascular aquatic plants, freshwater invertebrates (chronic and acute effects) and fish or frogs (chronic and acute effects). Modification of terrestrial-phase PCE Effects to riparian vegetation (terrestri al plants) result in LOC exceedances. Effects may result in changes in community composition or relative abundance of riparian plant species, possibly altering terrestrial – phase CRLF habitat. Chronic LOC is exceeded for mammal. Although there are NLAA determinations for other prey items, small mammals constitute up to half of the food intake for CRLF and reduction in small mammalian populations may be significant.
Based on the conclusions of this assessment, a formal consultation with the U. S. Fish and Wildlife Service under Secti on 7 of the Endangered Species Act should be initiated.
When evaluating the significance of this ri sk assessment’s direct/indirect and habitat effects determinations, it is important to not e that pesticide exposur es and predicted risks to the species and its resources (i.e., food and habitat) are not expected to be uniform across the action area. In fact, given the a ssumptions of drift and downstream transport (i.e., attenuation with distance), pesticide e xposure and associated ri sks to the species and its resources are expected to decrease with in creasing distance away from the treated field or site of application. Evaluation of the implication of this non-uniform distribution of risk to the species would require information and assessment techniques that are not currently available. Examples of such in formation and methodology required for this type of analysis would include the following:

• Enhanced information on the density and distribution of CRLF life stages withi n specific recovery units and/or designated critical habitat within the action area

. This information would allow for quantitative extrapolation of the present ris k

11 9assessment’s predictions of individual effects to the proportion of the population extant within geographical areas where those effects are predicted. Furthermore, such population information would allow fo r a more comprehensive evaluation of the significance of potential resource impairment to individuals of the species.

• Quantitative information on prey base requirements for individual aquatic- and terrestrial-phase frogs. While existing in formation provides a preliminary picture of the types of food sources utilized by the frog, it does not establish minimal requirements to sustain healthy individua ls at varying life stages. Such information could be used to establish bi ologically relevant thresholds of effects on the prey base, and ultimately establis h geographical limits to those effects. This information could be used together with the density data discussed above to characterize the likelihood of a dverse effects to individuals.

• Information on population responses of prey base organisms to the pesticide. Currently, methodologies are limited to pr edicting exposures and likely levels of direct mortality, growth or reproductive impairment immediately following exposure to the pesticide. The degree to which repeated exposure events and the inherent demographic characteristics of the prey population play into the extent to which prey resources may recover is not predictable. An enhanced understanding of long-term prey responses to pesticid e exposure would allow for a more refined determination of the magnitude and durati on of resource impairment, and together with the information described above, a more complete prediction of effects to individual frogs and potential modi fication to critical habitat.

12 08.0 References
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12 1McConnell, L.L., J.S. LeNoir, S. Datta, J.N. Seiber. 1998. Wet deposition of current-use pesticides in the Sierra Nevada mountainrange, California, USA. Environmental Toxicology & Chemistry 17(10):1908-1916.
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. 2001. Pesticides and amphibian population declines in California, USA. Environmental Toxicology & Chemistry 20(7): 1591-1595.

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. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs. Office of Preventi on, Pesticides, and Toxic Substances. Office of Pesticide Programs. Washington, D.C. January 23, 2004.

U.S. Fish and Wildlife Service (USFWS). 1996. Endangered and threatened wildlife and plants: determination of threatened status for the Californi a red-legged frog. Federal Register 61(101):25813-25833.
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USFWS. Website accessed: 30 December 2006. http://www.fws.gov/endangered/f eatures/rl_frog/rlfrog.html#where

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12 2Vogel, J.R., Majewski, M.S., and Capel, P. D. (2008) Pesticides in Rain in Four Agricultural Watersheds in the United St ates. J. Environ. Qual. V. 37 May-June 2008, pp. 1101-1115.

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