3

Table 1 . Listed Species Risks Associated with Potential Direct Effects Due to the Applications of Fosthiazate.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

aquatic plants

– monocots and dicots No effect

Aquatic plants No effect

Listed Animal Taxon Potential Direct Effects

Acute Notes Chronic Notes

Terrestrial invertebrates Yes (see note 1) 1. All potential direct effects identified are

expected to be limited to the site of application ( i.e ., treated tomato fields).

2 . Based on T

- REX, screening

- level RQ values exceed the listed species RQ for birds that weigh ≤ 100 g and eat arthropods. None of the RQs would exceed the acute LOC for listed birds (also surrogate for reptiles and terrestrial amphibians) that eat contaminated terrestrial invertebrates if the application scenario were modified by generally reducing the single maximum application rate to 1.0 lb a.i ./acre ( using 1 inch of irrigation water/acre ) or to ~0.5 lb a.i./acre (using 0.5 inches of irrigation water/acre)

Based on the Earthworm Fugacity model, screening

- level RQ values would not exceed the acute LOC for listed birds that eat contaminated earthworms if the application scenario were modified by generally reducing ND 4. Based on T

- R EX, screening

- level RQ values exceed the chronic LOC for mammals that weigh ≤ 35 g and eat arthropods. None of the RQs would exceed the chronic LOC for listed mammals that eat contaminated terrestrial invertebrates if the application scenario were modifie d by generally reducing the single maximum application rate to 1.0 lb a.i./acre ( usin g 0.5 inch es of irrigation water/acre ) or keeping the application rate at 1.5 lb a.i./acre and using ≥0.75 inches of irrigation water/acre.

Based on the Earthworm Fugacity model, screening

- level RQ values would not exceed the chronic LOC for listed mammals that eat contaminated earthworms if the application scenario were modified by generally reducing the single maximum application rate to 1.3 lb a.i./acre (using a K OC of 285 and a soil Mammals No effect See notes 1 and 4

Birds See notes 1 and 2 No effect

Reptiles See notes 1, 2 and 3 No effect

Amphibians See notes 1, 2 and 3 No effect

Freshwater fish No effect No effect

Freshwater invertebrates No effect No effect

Molluscs No effect ND

Estuarine/marine fish No effect No effect4

Listed Plant Taxon Potential Direct Effects

Estuarine/marine invertebrates No effect the single maximum application rate to 0.75 lb a.i./acre (using a K OC of 285 and a soil depth of 10 cm) or to 0.15 lb a.i./acre (using a K OC of 25 and a soil depth of 1.0 cm)

3. To help refine the risk assessment for terrestrial

- phase amphibians and reptiles that may eat invertebrates contaminated w ith fosthiazate, T

- HERPS (which uses feeding rates based on iguanids instead of birds) was used. Based on the T

- HERPS analysis, none of the RQs for amphibians or reptiles that eat terrestrial invertebrates exceed an Agency LOC

. Currently the Earthworm Fu gacity model does not calculate RQs for terrestrial

phase amphibians or reptiles that eat contaminated earthworms. Therefore, the potential risk to terrestrial

- phase amphibians or reptiles that specifically eat earthworms is uncertain. No effect depth of 10 cm) or to 0.26 lb a.i./acre (using a K OC of 25 and a soil depth of 1.0 cm)5

Based on this preliminary assessment, there are potential risks of direct effects to listed and non

listed birds (surrogates for terrestrial

- phase amphibians and reptiles), listed and non

- listed mammals, and terrestrial invertebrates from the use of fosthiazate on tomatoes. Listed species of other taxa may also be affected through indirect effects because of the potential direct effects on listed and non

- listed species. Potential direct effects on birds (surrogates for terrestrial

- phase amphibia ns and reptiles), mammals, and terrestrial invertebrates from the use of fosthiazate may be associated with modification of primary constituent elements of designated critical habitats, where such designations have been made. However, at this current stag e of the Registration Review process, it is premature to make effects determinations until further refinements are conducted. In order to make species

- specific effects determinations, useful refinements include the use of more detailed; 1) species

- specifi c ecological and biological data, 2) information on use patterns for fosthiazate , and 3) sub

- county level spatial proximity analyses for the co

- occurrence of potential areas of effects and listed species/designated critical habitat of concern. Examples of such refinements are described below.

EFED is currently developing tools that are expected to further refine the assessment and are designed to support effects determinations for individual federally listed species and their designated critical habitats ( where applicable). Scientific information obtained from the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and other reliable sources is being collated by EFED to address all currently listed species. The information will be stored in an Office of Pesticide Programs P esticide Registration Information SysteM (PRISM) knowledgebase . The listed species knowledgebase will consist of an information repository that houses biological and behavioral information relevant to ind ividual species ( e.g. , habitat, diet, and life history, including specific temporal and spatial associations) and a document repository that contains supporting documents ( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial taxa, the biological information relevant to r isk q uotient (RQ) calculations ( e.g ., diet and body weight) will be used to parameterize exposure estimates to derive species

- specific RQs using a method consistent with currently used methods in th e T

- REX and T

- HERPS models.

Refinements may also include more detailed analyses of the registered uses and their use patterns that result in LOC exceedances for federally listed species in the preliminary assessment. The analyses may include more information on where, when, and how fosthiazate is used on tomatoes

. Actual usage data (when available) and national land

- cover datasets that indicate potential use sites ( e.g ., national land cover dataset (NLCD) , crop data layer (CDL)) may be used to support a more refined analysis of where fosthiazate is reasonably expected to be used. Similarly, refinements for the timing of applications and how fosthiazate is used may be based

on the analysis of additional us age data , beyond what were available at the time of the screening

level assessment, and a more in

- depth exploration of agronomic practices.

In addition, a committee of the National Research Council (NRC) has been tasked with providing advice on ecologic al risk assessment tools and scientific approaches under ESA and FIFRA (Project Identification Number DELS

- BEST

- 11

- 01). The committee has been asked to review the use of “best available data;” methods for evaluating sublethal, indirect, and cumulative eff

ects; the state of the science regarding assessment of mixtures and pesticide inert ingredients; the development, application, and interpretation of results from predictive models;6

uncertainty factors; and what constitutes authoritative geospatial and temp oral information for the assessment of individual species and habitat effects. The Agency anticipates that this NRC report, tentatively expected in Spring 2013, will provide recommendations to ensure the scientific soundness and maximize the utility of ri sk assessment refinements for listed species.

The refinements based on individual species data ; additional, detailed usage information, when available ; and further recommendations from the NRC report are expected to help to more accurately identify potent ial areas of effect and to better inform effects and habitat determinations for listed species and any designated critical habitats. For example, if fosthiazate is used when a particular species of concern is not present ( e.g ., it is migratory) or is not co

located in space, then risk of potential direct effects to the species may often be precluded. If LOCs are still exceeded for birds (surrogates for terrestrial

- phase amphibians and reptiles), mammals, and terrestrial invertebrates after conducting the refined analyses, further analyses of the potential spatial and temporal co

- occurrence of listed species of concern (and any designated critical habitat) may be conducted. The extent of possible refinement in the analyses of spatial/temporal co

- occurrence will largely depend on the scale and quality of the available sub

county level use site ( e.g ., N ational L and C over D ataset , C ropland D ata L ayer ) and species location data

.7



### Ecological Risk Assessment for the Registration Review of Fosthiazate

O

- ETHYL - S

- (1

- METHYLPROPYL )(2

- OXO - 3

- THIAZOLIDINYL )

-

PHOSPHONOTHIOATE

(CAS Reg. No. 98886

- 44

- 3; USEPA PC Code: 129022)

Prepared by:

Melissa Panger, Ph.D., Senior Scientist James Wolf, Ph.D., Environmental Scientist

Reviewed by:

James Hetrick, Ph.D., Senior Advisor Rosanna Louie

- Juzwiak, Risk Assessment Process Leader

Approved by:

Dana Spatz, Branch Chief

Environmental Risk Branch III Environmental Fate and Effects Division Office of Pesticide Programs

U.S. Environmental Protection Agency 1200 Pennsylvania Avenue, NW Washington, D.C. 20460

March 20138



### Table of Contents

I. EXECUTIVE SUMMARY

................................ ................................ ................................ 9 A. Purpose of Assessment

................................ ................................ ........................... 9 B. Natur e of the Stressor

................................ ................................ .............................. 9 C. Summary of Effects and Risk Conclusions

................................ ............................ 9 II. PROBLEM FORMULATION

................................ ................................ .......................... 13 A. Pesti cide Type, Class, and Mode of Action

................................ .......................... 13 B. Overview of Pesticide Use and Usage

................................ ................................ .. 13 C. Previous Ecological Risk Assessments

................................ ................................ . 14 E. Analysis Plan and Conceptual Models

................................ ................................ . 18 1. Measures to Evaluate Risk Hypotheses

................................ .................... 18 2. Conceptual Model

................................ ................................ ..................... 18 3. Risk Hypo thesis

................................ ................................ ........................ 19 III. ANALYSIS

................................ ................................ ................................ ....................... 20 A. Measures of Exposure

................................ ................................ ........................... 20 B. Environmental Fate Characterization and Modeling Input Parameters

................ 22 C. Ecological Effects Characterization

................................ ................................ ...... 26 IV. RISK ESTIMATION

................................ ................................ ................................ ........ 28

1. Non

- target Aquatic Animals and Plants

................................ ................... 28 2. Non

- target Terrestrial Animals

................................ ................................ . 28 3. Probit Slope Response Analysis of LOC Values and Acute RQ Values

.. 30 V. RISK DESCRIPTION

................................ ................................ ................................ ...... 31

1. Review of Incident Data

................................ ................................ ........... 33 2. Ass umptions and Limitations

................................ ................................ ... 33 APPENDIX A. REFERENCES

................................ ................................ ................................ ... 37 APPENDIX B. BIBLIOGRAPHY

................................ ................................ .............................. 39 APPENDIX C. Sample Inputs and Outputs for the Earthworm Fugacity Model

........................ 42 APPENDIX D: ECOTOX Run

................................ ................................ ................................ .... 469

I. EXECUTIVE SUMMARY

A. Purpose of Assessment

The purpose of this assessment is to evaluate the potential risks of fosthiazates use on non

- target organisms, including federally listed endangered and threatened (listed) species. This risk assessment incorporates the available exposure and effects data and most current modeling and risk methodologies.

B. Nature of the Stressor

Fosthiazate is a systemic organophosphate (OP) nematicide/insecticide used for the control of a broad spectrum of nematode species in tomatoes. Although t he persistence and mobi lity of fosthiazate are conducive t o runoff and leaching, the approved application methods are designed to minimize potential transport to surface water. Labels require application through drip irrigation under plastic mulch. Therefore, spray drift to su rface water is not a concern, and the potential for runoff is reduced by the direct soil application and by the protection from precipitation. If fosthiazate does reach aquatic environments, it is stable to aquatic photolysis and has limited hydrolysis in neutral and acidic conditions, but it hydrolyzes rapidly in alkalin e conditions.

C. Summary of Effects and Risk Conclusions

The results of this preliminary risk assessment indicate that the registered use of fosthiazate on tomatoes has the potential for direct adverse effects to listed and non

- listed birds that weigh ≤100
g and ingest arthropods (acute exposure), listed and non

- listed mammals that weigh ≤35 g that ingest a r thropods (chronic exposure), and terrestrial invertebrates. Risks to terrestrial

- phase amphibians and reptiles that eat arthropods (in general) are not expected. There is a potential risk to listed and non

- listed birds, terrestrial

- phase amphibians, reptiles, and mammals that specifically eat earthworms (risks to amphibians and reptiles could not be precluded)

. The available acute toxicity data on fosthiazate (TGAI) indicate that it is highly toxic to birds, terrestrial invertebrates, f reshwater invertebrates, and estuarine/marine invertebrates; moderately toxic to small mammals; slightly toxic to estuarine/marine fish; and practically non

- toxic to freshwater fish. Avian reproduction studies showed significant effects on male and female weight gain, decreased eggshell thickness, and increased cracked eggs were observed in the bobwhite quail (NOAEC = 21.7 mg a.i./kg

- diet; LOAEC = 42.6 mg a.i./kg

- diet). A 2

- generation rat study yielded a reproductive NOAEL of 10 mg a.i./kg

- diet and a LOAE L of 30 mg a.i./kg

diet based on decreased viability index, litter size and pup weight for the f1 generation.

Chronic effects in the freshwater fish early life stage study included reduced dry weight and length of young fish (NOAEC = 2.32 mg a.i./L, LOAEC 4.48 mg a.i./L). The freshwater invertebrate life

- cycle study determined a NOAEC value of 0.061 mg a.i./L and a LOAEC value of 0.128 mg a.i./L based on reduced number of offspring produced and parental mortality.10

Tier I and Tier II terrestrial plant tox icity tests were performed on technical fosthiazate in which dicots appear to be more sensitive than monocots [Tier II seedling emergence test: NOAEC and EC 25 of 0.8 and 1.0 lb a.i./A, respectively (mustard); Tier II vegetative vigor, NOAEC and EC 25 of 0.8 lb a.i./A, respectively (buckwheat]. A Tier I test with the green alga ( Selenastrum capricornatum ) found no adverse effects at a concentration equal to 4.5 mg a.i./L.

Risks to aquatic organisms or terrestrial plants are not expected from the use of fo sthiazate on tomatoes. Risks are expected for terrestrial invertebrates [both soil

- dwelling (from direct exposure) and non

- soil

- dwelling (from ingestion of treated tomato plants)] and federally

- listed and non

- listed birds (acute) and listed and non

- listed mammals (chronic) from the ingestion of contaminated terrestrial invertebrates (including earthworms). Risks to terrestrial

- phase amphibians and reptiles that eat arthropods (in general) are not expected. There is a potential risk to listed and non

- list ed terrestrial

- phase amphibian s and reptiles that specifically eat earthworms (risks could not be precluded)

. Risks to birds (and, thus, reptiles and terrestrial

phase amphibians) and mammals from the ingestion of contaminated tomato plants are not expect ed.11

Table 1 . Listed Species Risks Associated with Potential Direct Effects Due to the Applications of Fosthiazate.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

aquatic plants

– monocots and dicots No effect

Aquatic plants No effect

Listed Animal Taxon Potential Direct Effects

Acute Notes Chronic Notes

Terrestrial invertebrates Yes (see note 1) 1. All potential direct effects identified are

expected to be limited to the site of application ( i.e ., treated tomato fields).

2 . Based on T

- REX, screening

- level RQ values exceed the listed species RQ for birds that weigh ≤ 100 g and eat arthropods. None of the RQs would exceed the acute LOC for listed birds (also surrogate for reptiles and terrestrial amphibians) that eat conta minated terrestrial invertebrates if the application scenario were modified by generally reducing the single maximum application rate to 1.0 lb a.i./acre ( using 1 inch of irrigation water/acre ) or to ~0.5 lb a.i./acre (using 0.5 inches of irrigation water/acre)

Based on the Earthworm Fugacity model, screening

- level RQ values would not exceed the acute LOC for listed birds that eat contaminated earthworms if the application scenario were modified by generally reducing ND 4. Based on T

- REX, screening

- level RQ values exceed the chronic LOC for mammals that weigh ≤ 35 g and eat arthropods. None of the RQs would exceed the chronic LOC for listed mammals that eat contaminated terrestrial invertebrates if the application scenario were modified by generally reducing the single maximum application rate to 1.0 lb a.i./acre ( usin g 0.5 inch es of irrigation water/acre ) or keeping the application rate at 1.5 lb a.i./acre and using ≥0.75 inches of irrigation water/acre.

Based on the Earthworm Fugacity model, screening

- level RQ values would not exceed the chronic LOC for listed mammals that eat contaminated earthworms if the application scenario were modified by generally reducing the single maximum application rate to 1.3 lb a.i./acre (using a K OC of 285 and a soil Mammals No effect See notes 1 and 4

Birds See notes 1 and 2 No effect

Reptiles See notes 1, 2 and 3 No effect

Amphibians See notes 1, 2 and 3 No effect

Freshwater fish No effect No effect

Freshwater invertebrates No effect No effect

Molluscs No effect ND

Estuarine/marine fish No effect No effect12

Listed Plant Taxon Potential Direct Effects

Estuarine/marine invertebrates No effect the single maximum application ra te to 0.75 lb a.i./acre (using a K OC of 285 and a soil depth of 10 cm) or to 0.15 lb a.i./acre (using a K OC of 25 and a soil depth of 1.0 cm)

3. To help refine the risk assessment for terrestrial

- phase amphibians and reptiles that may eat invertebrates c ontaminated with fosthiazate, T

- HERPS (which uses feeding rates based on iguanids instead of birds) was used. Based on the T

- HERPS analysis, none of the RQs for amphibians or reptiles that eat terrestrial invertebrates exceed an Agency LOC

. Currently the Earthworm Fugacity model does not calculate RQs for terrestrial

phase amphibians or reptiles that eat contaminated earthworms. Therefore, the potential risk to terrestrial

- phase amphibians or reptiles that specifically eat earthworms is uncertain. No effect depth of 10 cm) or to 0.26 lb a.i./acre (using a K OC of 25 and a soil depth of 1.0 cm)13

II. PROBLEM FORMULATION

A. Pesticide Type, Class, and Mode of Action

Fosthiazate is a systemic organophosphate (OP) nematicide/insecticide used for the control of a broad spectrum of nematode species in tomatoes. Fosthiazate also suppresses insects including sweet potato whitefly, tomato pinworm, and beet armyworm in tomat oes. Current labels allow application of fosthiazate to the soil prior to receiving transplanted tomatoes at a maximum annual rate of 1.5 lb active ingredient (a.i.)/planted acre. It must be applied through drip irrigation systems placed under plastic mu lch. Fosthiazate is active against invertebrates via contact and oral exposure. As an OP, its mode of action is considered to be through acetyl cholinesterase inhibition (AchEI), although fosthiazate itself is only a weak inhibitor of AchEI in in vitro s tudies (USEPA, 2009). Fosthiazate is activated as a cholinesterase inhibitor by mixed function oxidase or other intracellular oxidation processes.

B. Overview of Pesticide Use and Usage

Fosthiazate is registered for use on tomatoes at a maximum annual rate of 1.5 lb active ingredient (a.i.)/planted acre. It must be applied through drip (trickle) irrigation systems placed under polyethylene plastic mulch (which is impervious) before seeding or transplanting. Based on information in sample state crop profil es (e.g., North Carolina Crop Profile Tomato Plastic Mulch, Crop Profile for Tomatoes in Arkansas), the plastic mulch is placed over raised beds and remains on the beds until after harvesting (the space between the beds is not treated). Registered formula tions of fosthiazate include the technical product [Technical Fosthiazate, 96% a.i. (EPA Reg. No. 71512

- 6)], as well as three end use products (all single a.i.), two of which are Restricted Use Pesticides (see Table 1). Targeted pests include the control of various nematodes [ e.g ., root

- knot nematode (Meloidogyne incognita) and spiral nematode (Helicotylenchus spp.)] and the suppression of various insects ( i.e. , potato whitefly, tomato pinworm and beet armyworm).

TABLE 2. Registere d Fosthiazate End

- Use Products.

PRODUCT NAME (EPA REG. NO.) %

A.I. USE SITE MAXIMUM

SINGLE APPLICATION RATE MAXIMUM

ANNUAL APPLICATION RATE APPLICATION

METHOD COMMENT(S)

Fosthiazate 900EC (71512

- 4) 75 Tomato 1.5 lb a.i./ planted acre/ crop cycle Not reported 1 Drip irrigation under plastic mulch Restricted Use

Pesticide ; do not treat more than 25 acres per day per application

Fosthiazate 75% EC (71512

- 17) 75 Tomato 1.5 lb a.i./ planted acre/ crop cycle Not reported 1 Drip irrigation under plastic mulch Restricted Use

Pesticide ; do not treat more than 25 acres per day per application Nemathorin® 500EC (71512

- 5) 47.2 Tomato 1.5 lb a.i./ planted acre/ crop cycle 1.5 lb a.i./planted

acre/year Drip irrigation

under plastic mulch Do not treat more

than 25 acres per day per application
1 The pro duct must be used prior to seeding or transplanting, h owever, a maximum application rate per year is not14

PRODUCT NAME (EPA REG. NO.) %

A.I. USE SITE MAXIMUM

SINGLE APPLICATION RATE MAXIMUM

ANNUAL APPLICATION RATE APPLICATION

METHOD COMMENT(S)

specified. Therefore, it is assumed that there will be one application per crop cycle.

There are no usage data available for fosthiazate [ i.e., the use of fosthiazate has not been reported in the available usage databases ( i.e ., United States Department of Agriculture’s National Agricultural Statistics Service, private pesticide market research, and California Department of Pes ticide Regulation Pesticide Use Reporting)].

C. Previous Ecological Risk Assessments and Evaluations

Fosthiazate was first registered in 2004. As part of the initial registration, the ecological risks associated with several proposed different application methods and rates for the tomato use were assessed [USEPA

, 2002 (December)]. In that assessment, the EPA found that when fosthiazate is applied as a broadcast (3 to 4.5 lb a.i./A) or banded spray (1 to 1.5 lb a.i./A), there were concerns for a cute risk to birds, mammals and insects (such as honey bees) as well as chronic risk to birds and mammals. When fosthiazate is applied as a broadcast (3 to 4.5 lb a.i./A) or banded spray (1 to 1.5 lb a.i./A) its use may pose acute and chronic risk to liste d birds and mammals as well as acute risk to listed terrestrial invertebrates. However, when fosthiazate is applied by shank injection or chemigation under plastic mulch, fosthiazate poses minimal acute or chronic risk to listed or non

- listed, non

- target animals and plants. The only RQs for aquatic organisms that exceeded EPA levels of concern (LOC) were the acute RQs for freshwater aquatic invertebrates based on a 4.5 lb a.i./A broadcast spray, which exceeded the acute listed species LOC. Subsequently, on ly application via chemigation (drip irrigation) under plastic mulch of fosthiazate prior to seeding or transplanting tomatoes, was registered.

The new chemical assessment (USEPA, 2002) identified some data gaps for the broadcast and banded uses of fosth iazate ( i.e ., freshwater invertebrate life

- cycle, mysid shrimp life cycle, Tier II seedling emergence, Tier II vegetative vigor, and acute honey bee contact); however, the data set for the drip irrigation uses was considered complete.

An ecological risk a ssessment was also conducted for proposed new uses of fosthiazate in 2008 (USEPA

, 2008a). This assessment assessed the risks associated with proposed new uses on peanuts (4.0 lb a.i./A) and potatoes (4.5 lb a.i/A) and an increased application rate for tom atoes (4.5 lb a.i./A). Fosthiazate was found to present acute risk to birds and mammals and chronic risk to endangered birds and mammals. Acute and chronic risk to freshwater and estuarine/marine fish and estuarine/marine invertebrates was found to be be low the level of concern, but there was a potential for acute risk to freshwater invertebrates from the proposed uses. Minimal risk was found for terrestrial and aquatic plants. To date, these uses have not been registered, and will not be considered fur ther in this preliminary registration review risk
assessment.

Subsequent to the 2008 new use assessment, a Problem Formulation (PF) was completed for Registration Review (USEPA

, 2009). The PF addressed the use pattern considered in this assessment (tomat o use; drip irrigation under plastic mulch; 1.5 lb a.i./A maximum annual15

application rate) and is the basis for this risk assessment. The PF concluded the following regarding risks to non

- target organisms from the use of fosthiazate on tomatoes:

“Due to the application method, aquatic exposure will be low and risk to aquatic organisms is minimal. In the new chemical assessment, uses of fosthiazate at twice the currently labeled rate applied through broadcast spray did not exceed any aquatic levels of con cern. With the drip irrigation method required by current labels, drift to surface water is not a factor, and because fosthiazate is applied directly to soil in low amounts of water and is protected from precipitation by the plastic mulch, runoff is unlik ely. Therefore, previous assessments concluded that any aquatic exposure from the current use on tomatoes will be substantially lower than in those estimated for other uses and so there will still be no exceedances.

In the terrestrial environment, there is some potential for dietary exposure to birds and mammals who probe beneath the surface for seeds and insects or which feed on emerging seedlings containing translocated residues. This exposure is unquantifiable and expected to be negligible, so there i s minimal risk to terrestrial organisms as well.” (pp. 8

– 9). ”

The data set for the drip irrigation use on tomatoes was considered complete. Therefore, no new data were requested for fosthiazate in the PF. Since the PF, additional data on the transloca tion of fosthiazate in tomato plants have become available in the open literature ( e.g ., Mukherjee, et al., 2011; Sharma and Kumar, 2011). These studies are considered in this assessment.

D. Assessment Endpoints

The available acute toxicity data on fosthia zate (TGAI) indicate that it is highly toxic to birds, freshwater invertebrates, and estuarine/marine invertebrates; moderately toxic to small mammals; slightly toxic to estuarine/marine fish; and practically non

- toxic to freshwater fish. A summary of the toxicity data and the resulting measures of ecological effect selected for each taxonomic group are included in Table 3

.

TABLE 3 . Summary of the Most Sensitive Measures of Effects (for Each Taxon) of Fosthiazate.

STUDY REGISTRANT SUBMITTED STUDIES

MRID CLASSIFICATION MEASURES OF EFFECTS

Acute Avian Oral [Northern Bobwhite Quail ( Colinus virginianus )] 43916819 Acceptable LD 50 = 10.6 mg a.i./kg

- bw

Acute Avian Dietary [Northern Bobwhite Quail ( Colinus virginianus )] 41381106 Supplemental (the birds were not randomly assigned to treatment groups) LC 50 = 85 mg a.i./kg

- diet16 STUDY REGISTRANT SUBMITTED STUDIES

MRID CLASSIFICATION MEASURES OF EFFECTS

Avian Reproduction [Mallard Duck (

Anas platyrhynchos )] 43916825 Acceptable NOAEC = 21.7 mg a.i./kg

- diet LOAEC = 42.6 mg a.i./kg

- diet (based on reduced weight gain, decreased eggshell thickness and increased cracked eggs)

Avian Reproduction [Northern Bobwhite Quail ( Colinus virginianus )] 43916824 Acceptable NOAEC = 21.7 mg a.i./kg

- diet LOAEC = 42.6 mg a.i./kg

- diet (based on reduced weight gain, decreased eggsh ell thickness and increased cracked eggs)

Acute Rat Oral 41347622 Acceptable LD 50 = 51 mg a.i./kg

- bw (females)

Rat Reproductive Development 41381113;

44414501 Acceptable NOAEL = 10 mg a.i./kg

- diet LOAEL = 30 mg a.i./kg

- diet (based on decreased viability index, litter size for the f 1 generation and pup weight)

Honey Bee Acute (

Apis mellifera ) 41347636 Acceptable LD 50 = 0.247 μg a.i./bee (contact)

Freshwater Fish Acute Toxicity [Rainbow Trout ( Oncor h ynchus mykiss )] 43916826 Acceptable LC 50 = 111 mg a.i./L

Freshwater Fish Early

- Life Stage [fathead minnow ( Pimephales promelas )] 45540404 Acceptable NOAEC = 2.32 mg a.i./L LOAEC = 4.48 mg a.i./L (based on reduced dry weight and length)

Estuarine/Marine Fish Acute Toxicity [Sheepshead minnow ( Cyprinodon variegatus )] 45540403 Acceptable LC 50 = 46.5 mg a.i./L

Estuarine/Marine Fish Chronic No data available

Freshwater Invertebrate Acute Toxicity [Daphnid ( Daphnia magna )] 43916828 Acceptable EC 50 = 0.26 mg a.i./L

Freshwater Invertebrate Life

- Cycle [Daphnid ( Daphnia magna )] 43916829 Supplemental (the length and weight of the offspring were not measured) NOAEC = 0.061 mg a.i./L

LOAEC = 0.128 mg a.i./L (based reduced reproduction and parental mortality)

Estuarine/Ma rine Acute Invertebrate [Eastern oyster ( Crassostrea virginica ); shell deposition] 45540401 Acceptable EC 50 = 14.1 mg a.i./L17 STUDY REGISTRANT SUBMITTED STUDIES

MRID CLASSIFICATION MEASURES OF EFFECTS

Estuarine/Marine Acute Invertebrate [Mysid ( Americamysis bahia )] 45540402 Acceptable LC 50 = 0.429 mg a.i./L

Estuarine/Marine Invertebrate Chronic No data available

Terrestrial Plants (Seedling Emergence) 43916839 Supplemental (raw data were not submitted) Most Sensitive Dicot 1 :

Mustard

– NOAEC = 0.8 lb a.i./A

EC 25 = 1.0 lb a.i./A Endpoints based on reduced fresh weight

Most Sensitive Monocot :
None

– NOAEC = 6.0 lb a.i./A

EC 25 > 6.0 lb a.i./A

Terrestrial Plants (Vegetative Vigor) 43916840 Acceptable Most Sensitive Dicot 1 :
Buckwheat

– NOAEC = 0.8 lb a.i./A

EC 25 = 3.3 lb a.i./A

Most Sensitive Monocot : Sorghum

– NOAEC = 3.0 lb a.i./A

EC 25 > 6.0 lb a.i./A Endpoints based on reduced shoot weight

Aquatic Plants Non

Vascular 2 [Green Algae ( Selenastrum capricornatum )] 43916821 Acceptable EC 50 > 4.51 mg a.i./L NOAEC = 4.51 mg a.i./L (the highest concentration tested)

Aquatic Plant Vascular No data available

1 Although peppers showed a greater than 25% effect response in the Tier I study, they were not included in the Tier II study.
2 Data are only available for one of the four typically required aquatic non

- vascular plant species.

Open Lit e rature

Additional toxicity data were located in the open literature using the ECOTOXicology database, however, none of the acceptable studies had endpoints that were more sensitive than those from the submitted studies (see Appendix D ).

To assess exposure from the uptake of fosthiazate in the tomato plants, data available from the open literature are considered for this assessment (Mukherjee, et al . 2011; Sharma and Kumar, 2011; Wu, et al. 2012) (see the ‘Measures of Exposure’ section below for details).18

E. Analysis Plan and Conceptual Models

1. Measures to Evaluate Risk Hypotheses

In the case of fosthiazate, m easures of exposure are based on terrestrial models that estimate environmenta l concentrations of fosthiazate using maximum labeled application rates. The model used to produce terrestrial EECs on food items is T

- REX. For more information on EPA’s models, visit http: //www.epa.gov/pesticides/science/models_db.htm

. The most sensitive toxicity endpoints from surrogate test species are used to estimate trea tment

- related effects on growth, reproduction and /or survival.

Measures of effect are obtained from a suite of st udies conducted with a limite d number of surrogate species. The test species are not intended to be representative of the most sensitive species but rather are selected based on their ability to thrive under laboratory conditions.

2. Conceptual Model

The conceptual model is a graphic representation of the structure of the risk assessment. It specifies the fosthiazate release mechanisms, biological receptor types, and effects endpoints of potential concern. The conceptual model for terrestrial exposur e is shown in Figure 1 (aquatic exposures are not expected). For the registered use, fosthiazate is applied to tomatoes via drip irrigation under plastic mulch. The only potential exposure pathways to non

- target organisms are via direct application (for soil

- dwelling invertebrates) and ingestion of contaminated invertebrates and/or ingestion of tomato plant parts in which fosthiazate has been translocated. D ashed lines (such as for spray drift, runoff, leaching, and atmospheric transport) denote
exposure routes not assessed due to the likelihood of low potential exposure.19 3. Risk Hypothes i s

A risk hypothesis describes the predicted relationship among the stressor, exposure, and assessment endpoint response along with the rationale for their selection. For fosthiazate , the following ecological risk hypothesis is being employed for this national

- level ecological risk
assessment:

Fosthiazate , when used in accordance with current labels, can result in exposure

to non

- target terrestrial animals. Exposure via direct applications (soil

- dwelling invertebrates) and/or via ingestion of contaminated invertebrates and/or part(s) of the treated tomato plant may be above levels where adverse effects upon the survival, growth, and reproduction of non

- target terrestrial animals (including federally

- listed threatened and endangered species ) would occur

.20

III. ANALYSIS

A. Measures of Exposure

As discussed in the Registration Review Problem Formulation for fosthiazate, previously assessed broadcast uses of fosthiazate that had twice the labeled application rate as the registered tomato use did not exceed any aquatic levels of concern. With the drip irrigation method required by current labels, drift to surface water is not a concern, and because fosthiazate is applied directly to soil in low amounts of water and is protected from precipitation by the plastic mulch, any appreciable runoff is unli kely. The persistence and mobility of fosthiazate and the MBSo/MBSx and BSA degradates 1 suggest that the potential exists for leaching to groundwater. Previous assessments concluded that any aquatic exposure from the current fosthiazate use on
tomatoes will be substantially lower than estimated for other previously assessed uses and no aquatic LOC exceedances are expected. Therefore, risks to aquatic organisms (plants or animals) are not expected from the registered use and aquatic exposure values will not be calculated in this assessment. Risk from exposure from groundwater is expected to be less than for surface water from previously assessed broadcast uses, and, therefore, additional analysis for exposure via groundwater was not done.

The only poten tial exposures expected from application via drip irrigation (under plastic mulch) are to soil

- dwelling invertebrates (direct application) and to animals ( e.g ., terrestrial invertebrates, birds, and mammals) that may feed directly on tomato plant parts in which fosthiazate has been translocated ( e.g ., roots, leaves, stems, fruits, flowers, pollen, nectar) or contaminated soil

- dwelling invertebrates. Therefore, potential exposures are expected to be limited to the site of application. Risks to non

- target t errestrial plants are not expected due to limited exposure potential. Currently, there are no standard methods for quantitatively assessing risks to soil

- dwelling invertebrates from direct exposure to pesticides via drip irrigation or risks associated wit h systemic pesticides. Therefore, potential risks to non

- target terrestrial animals will not be assessed using the standard methodology.

For direct exposure to soil

- dwelling invertebrates, information from the labels is used to estimate a concentration of the a.i. in the irrigation water that is used to apply fosthiazate that can be compared to the available toxicity endpoint for bees (contact). The current labels state that 0.5 to 1 inch of irrigation water per acre is required for the incorporation of fosthiazate. The highest concentration of a.i. in the irrigation water would be with the application of 0.5 inch of irrigation water/acre. Therefore, the 0.5 inch of water/acre is used for modeling. One

- acre inch of water is equal to 27,154 gallons; th erefore, 0.5 acre inches of water = 13,577 gallons (which equals 51,395 L). The maximum allowed application rate for fosthiazate is 1.5 lb a.i./A, which equals 680,389 mg a.i./acre. This results in a concentration of 13.2 mg a.i./L ( i.e ., 680,389 mg a.i. /51,395 L). This concentration is used to assess exposure and potential risks to terrestrial invertebrates.

This concentration [ i.e ., 13.2 ppm (mg/kg)] is also used to calculate the concentration found on contaminated arthropods that may be ingested by listed and non

- listed birds and mammals that

1 MBSo: sec

- butyl methyl sulfone; MBSx: sec

- butyl methyl sulfoxide; and BSA: 2

- Butanesulfonic acid21

may probe for arthropod prey under the plastic mulch. To account for the mass of the ingested invertebrate(s), the average fresh weight of an adult honey bee of 128 mg (Mayer and Johansen, 1990) is used as a su rrogate for the mass of soil

- dwelling arthropods. Adjusting for the weight of the bee exposed to 13.2 ppm of fosthiazate, results in a concentration of 1.7 ppm/arthropod (13.2 mg a.i./L x 0.128 mg). This number can then be used as the estimated environme ntal exposure (EEC) for arthropods in T

- REX (v 1.5).

The T

- REX model is useful for assessing exposures of terrestrial animals to pesticide residues on foliar surfaces of crops and seeds. The model cannot be used to assess pesticide exposures to terrestrial animals resulting from consumption of earthworms contaminated with pesticide mass present in the soil of the application site. Therefore, in order to explore the potential exposures of mammals and birds to pesticides in the soil and earthworms on the treatment site, a simple fugacity approach (an ‘earthworm fugacity’ model) was also employed to estimate concentrations of the pesticide of interest in earthworms (see APPENDIX C for details ). In this approach, it is assumed that a pesticide partitions between the soil, the (pore) water and the air contained within the soil of the treatment site. It is assumed that earthworms dwelling within the soil are exposed to a pesticide via ingestion of contaminated soil. In this model, it is assumed that assessed mammals and birds consume only earthworms ( i.e., vermivores) from the treatment site. The earthworm fugacity model uses the maximum average concentration in the soil (modeled using PRZM). A range of both K oc values (25 and 285) and modeled depths (1.0 cm and 10.0 cm) were used to bound the potential soil concentrations. In order to assess acute dose

based and dietary

- based exposures of vermivores to pesticides, an approach similar to the one employed by the T

- REX model is used

. To estimate potential exposures for terrestrial animals feeding on parts of tomato plants in which fosthiazate has been translocated, we relied on data from fosthiazate uptake studies in tomatoes that had been tran splanted into treated soil ( i.e ., Sharma and Kumar, 2011 ; Sharma and Kumar, 2011b; and Wu, et al ., 2012 ) . Based on these data, a maximum of 0.489% of the applied fosthiazate is absorbed by the plant (for fosthiazate applied via drip irrigation with a surf actant). Therefore, to estimate the mass of the pesticide in each plant, the application rate ( i.e ., 1.5 lb a.i./A) can be multiplied by 0.00489. This results in a value of 0.007 lb a.i./A of plants ( i.e

., 3175 mg a.i./A of plants). To calculate a conce ntration per plant , the fresh weight of tomato plants is needed along with the number of plants per acre . Based on data from Wu, et al. (2012), fresh shoot weight of tomato plants at 12 weeks ranged from 3.59 to 2.67 kg/plant . Twelve weeks is a time

- frame which would allow for uptake

– tomato plants are typically transplanted at 4

– 6 wks old

. Using the lower end of the range ( i.e ., 2.67 kg/plant) and a lower bound number of plants per acre [ i.e ., ~3,700

– 5,000 plants/acre (Crop Profile for Tom atoes in Arkansas; Commercial Tomato Production Handbook)] results in 9,879 kg of tomato plants per acre (3,700 plants x 2.67 kg/plant). Therefore, a peak fosthiazate concentration of 0.32 ppm is expected in the tomato plants (3,175 mg a.i./9,879 kg plant ) (it is assumed that all parts of the plant have this same fosthiazate concentration). This number can then be used as the estimated environmental exposure (EEC) via ingestion of plants in T

- REX (v 1.5). No data are available for the translocation of fo sthiazate in plants grown from seed. However, since the soil treatment is identical for tomatoes grown from seed and from transplant, we assume that the amount of fosthiazate translocated in the plants will be similar

.22

B. Environmental Fate Characterizatio n and Modeling Input Parameters

The p hysical/chemical properties and environmental fate properties of fosthiazate are listed in Table 4

. In aerobic soils, measured half

- lives were 14.0 to 57.7 days with the appearance of slower metabolism in acidic soils (t 1/2 = 41.8 to 57.7 days) than in alkaline soils (t 1/2 =14.0 to 20.7 days). Substantial degradation was seen in sterile controls as well, suggesting that some of the transformation occurs through abiotic processes. Laboratory studies suggest that persi stence of fosthiazate in soils will be on the scale of weeks to months, with rates depending on soil pH. Terrestrial field dissipation (TFD) half

- lives ranged from 7 to 40 days depending upon location and formulation. The influence of soil pH on half

- life was not observed in the TFD studies. The terrestrial field dissipation studi es were conducted in soils that are expected to be relatively permeable (sand content generally > 50 %

- sandy clay loam to loamy sand). The refore, the terrestrial field dissipation half

- lives may reflect the differences in leaching between the different study site locations. The soil partition coefficients (K ads ) ranged between 0.43 and 2.77 mL/g. Fosth iazate has low sorption to soil and th e sorption of fosthiazate is correlated (p

- value = 0.05) to soil organic carbon content. Based on K oc , values ranging from 25 to 285.7 mL/g oc , fosthiazate is classified as mobile to moderately mobile by the FAO classification scheme (FAO, 2000). Sorption did not appear to be correlated to soil pH. Based upon its vapor pressure, the volatility class for fosthiazate from dry non

- adsorbing surfaces is between “non

- volatile under field condition” and “intermediate to high volatility under field condition” (4. 20 x 10 - 6 torr).

The persistence and mobility of fosthiazate are conducive to runoff and leaching. However, t he approved application methods are designed to minimize potential transport to surface water. Labels require application through drip irrigatio n under plastic mulch. Therefore, spray drift to surface water is not a concern, and the potential for runoff is reduced by the direct soil application and by the protection from precipitation. If any fosthiazate does reach aquatic environments, it is st able to aquatic photolysis and has limited hydrolysis in neutral and acidic conditions, but it hydrolyzes rapidly in alkaline conditions. It is moderately persistent in water

sediment systems, with an average half

- life, using linear regression, in aerobic aquatic environments of 51 days and in anaerobic aquatic environments of 32 days.

Terrestrial field dissipation (TFD) studies were conducted with 4 lbs a.i./A, applied as emulsifiable concentrate (EC) and granular formulations, to bare ground and incorporated 4 to 5 inches with no plastic mulch. In three sites, calculated half

- lives we re 9 to 17 days, and in a fourth site, the half

- life was 40 days for the granular formulation. For the EC formulation the calculated half

- lives ranged from 7 to 15 days, at the three sites, and at the fo u rth site 28 days. Because the laboratory aerobic m etabolism studies suggest that soils with a n acidic pH were more persistent, all studies were conducted at sites with acidic soils (pH <6.6). Soils were also selected to represent soils with higher leaching potentials as all contained 50 percent or more

s and. In most cases, fosthiazate residues were detected to no more than 15

- 30 cm below the soil surface. I n three samples collected at the Georgia site

, fosthiazate residues were found at low levels (≤0.02 mg/kg) up to 46 cm below the soil surface. Degrad ates MBSo/MBSx and BSA were not detected in samples collected below 0

- 15 cm.23

In the registered use, the plastic mulch cover would minimize volatilization and runoff; therefore, increasing the amount of the chemical available for leaching. However, with t he drip irrigation method, a small amount of water is slowly dripped into soils precisely where it is needed, thus lessening the amount of water flowing down through the soil past the root zone where it cannot be used by the crop. This greatly reduces the potential for the chemical to reach ground water.

Based on the results of the fish accumulation study, the bioconcentration factors were 2.3X for edible tissue, 4.5X for non

- edible tissue, and 3.2X for whole body tissue after 28 days exposure and a 14

- da y depuration period , suggesting low bioaccumulation potential

. By day 14 of the depuration period 78%, 81% and 80% of the 14 C

- residues had been eliminated from the edible,

non

- edible and whole body tissue portions, respectively.

TABLE 4

. Physical/chemical Properties and Environmental Fate Properties of Fosthiazate.

PARAMETER VALUE(S) SOURCE (Study Acceptability Classification) a COMMENTS

Molecular Structure

Chemical Name O

- Ethyl S

- (1

- methylpropyl)(2

- oxo

- 3

- thiazolidinyl ) phosphonothioate

Chemical Class Organophosphate (OP)

Molecular Formula C 9 H 18 NOPS 2 MRID 47223201

Molecular Weight 283.36
Solubility in water (25 o C) 9880 mg/L@ pH5 9000 mg/L @ pH 7 9460 mg/L @ pH 9 MRID 47223201

Vapor Pressure (25 o C) 4.20 x 10 - 6 mm Hg MRID 47223201
Henry’s Law Constant (25 o C) 1.74 x 10 - 10 atm m 3 /mol Calculated Henry’s Law Constant = [Vapor Pressure (mm Hg)/760 mm Hg)] x [Mole Weight (g/mole)/Solubility (ppm)]
Hydrolysis Half

- life (25 o C) 177 days @ pH 5 104 days @ pH 7 3.2 days @ pH 9 MRID 41347637 (a)

Aqueous Photolysis Half

- life (pH 4) stable MRID 43916831(a)24

PARAMETER VALUE(S) SOURCE (Study Acceptability Classification) a COMMENTS

Aerobic Soil Metabolism Half

- life LR c T 1⁄2 = 41.75, 45.89 days @ pH 6.1

53.3 to 57.7 days @ pH <6.1 b 14.0 to 20.7 days @ pH >7.0 b MRID 43916832 (a)

MRID 47098902 (s) MRID 47098902 (s) One soil with carbonyl and butyl labels

Pantelelis et al.,2006 (this publication is included in MRID 47098902)
Anaerobic Aquatic Soil Metabolism 32 days MRID 43916833 (a) Represents average of 31 days (carbonyl label) 33 days (butyl label) for one

soil
Aerobic Aquatic Metabolism Half

- life Total System

river sediment (Ohio) LR T 1⁄2 - 72.3 days Non

- LR d T 1⁄2

- 70.0 days river sediment (German) LR T 1⁄2 - 29.5 days Non

- LR T 1⁄2

- 39.8 days MRID 47098903 (s) The LR T 1⁄2 is used because the fate and transport models used by EFED use simple first

- order kinetic models.

Soil Partition Coefficient (K d ) (mL/g) K d = 0.43, 1.22, 1.71

1.48 to 2.77 (n=9) MRID 41347639 (a) MRID 41347640 (s) MRID 47098902 (s) Pantelelis et al.,2006 (in MRID 47098902)
Organic Carbon Partition Coefficient (K oc ) (mL/g oc ) K oc = 45.3, 96.2, 24.8

205.0 to 285.7 (n=9) MRID 41347639 (a)

MRID 47098902 (s) -

Pantelelis et al.,2006 (included in MRID 47098902)

Log Octanol/water partition coefficient (K ow )(25 ◦ C) 1.752 MRID 47223201

Terrestrial Field Dissipation Half

- life Study Location: LR T 1⁄2 [pH f ] Formulation: EC Granular WA: 15 d 17 d [≤5.5] CA: 28 d 40 d [5.6

– 6.6] GA: 16 d 13 d [< 5.5, surface sample = 6]

- NC: 7 d 9 d [<4.6 surface sample = 6.3] MRID 43952901 (a) MRID 43952902 (a) MRID 43952903 (a) & MRID 43916835 MRID 43952904 (a) EC and Granular Formulations of fosthiazate w ere applied to bare ground plots at ~4.5 lb a.i./A with no plastic mulch Analytes in all studies included parent and degradates MBS and BSA e

.

Bioconcentration Factor (BCF) in fish 2.3 to 4.5X MRID 41347642 (a)

a * (a) = acceptable study that fulfills guideline requirement; (s) = supplemental study

b Total of 9 soils, 3 with pH <6.1 and 6 with pH > 7.0

c LR is Single First

- Order (SFO) linear regression

d Non

- LR is Single First

- Order (SFO) non

- linear regression

e Degradates: MBS (2

- (Methylsulfonyl) butane) and BSA (2

- Butanesulfonic acid),

f Soil pHs for soil increments sampled in the terrestrial field dissipation studies.2 5

As summarized in Table 5 , carbon dioxide and bound residues were the primary end products in most cases. Additionally, s ix degradation products were identified : (RS)

- S

- sec

- butyl hydrogen 2

- oxo

- 1,3

- thiazolidin

- 3

- ylphosphorothioate (DETO), O

- ethyl

- 2

- oxo

- 1,3

- thiazolidin

- 3

- ylphosphonate (DBTO), 1,2

- thiazolidin

- 2

- one (TZO), (RS)

- S

- sec

- butyl O

- ethyl hydrogen phosphorothioate (DTTO), sec

- butyl methyl sulfone (MBSo), sec

- butyl methyl sulfoxide (MBSx), and 2

- Butanesulfonic acid (BSA) were detected along with unidentified organic volatiles. Study lengths were not sufficient to determine the pattern of formation and decline for all degradates. The only degradates found in te rrestrial field dissipation studies were MBSo/MBSx which at maximum represented about 1 to 4 % of applied (maximum fosthiazate concentration = 2.2 mg/kg). The maximum MBSo/MBSx soil concentration was 0.06 mg/kg and the maximum BSA soil concentration was 0. 1 mg/kg. These degradates were not detected below the shallowest sampling increment (0

- 15 cm). In the column leaching studies, the three major degradation products recovered in the leachate were TZO, DTTO, and DEDT ( (RS)

- S

- sec

- butyl

phosphorothioate) at 2.6%, 7.8%, and 42.5% of applied radioactivity, respectively.

Table 5 . Major degradates of fosthiazate, as a percentage of applied parent Degradates b Study Type (Study Length) a

Hydrolysis Aerobic Soil (150 d) Aerobic

Aquatic (140 d) Anaerobic

Aquatic Soil (120 d) pH 5 (30 d) pH 7

(30 d) pH 9

(14 d) DETO ~13 % ~13 % up to 10% c minor DBTO 45%

TZO 40% 32% (60 d) DTTO 44% up to 10% c minor MBSo/ MBSx d 11% (28

– 35 d) 16.4%

(60 d) BSA 20% Unid entifie d organic volatile s ~30% 8%

CO 2 27

– 67% 31.9% 43%

a Unless otherwise noted, maximum concentrations occurred at study termination.
b DETO : (RS)

- S

- sec

- butyl hydrogen 2

- oxo

- 1,3

- thiazolidin

- 3

- ylphosphorothioate; DTTO : (RS)

- S

- sec

- butyl O

ethyl hydrogen phosphorothioate; MBSo : sec

- butyl methyl sulfone; MBSx : sec

- butyl methyl sulfoxide; BSA : 2

- butanesulfonic acid.

c Aerobic aquatic study did not separate DETO/DTTO.
d MBSo/MBSx not separated.

Additional information concerning the environmental fate of fosthiazate is described in the New Chemical Assessment for Fosthiazate (USEPA, 2002, D229582).

a) Monitoring Data

F osthiazate was not included as one of the residues analyzed for in groundwater at the time that the Pesticides in Ground Water Data Base was published, in 1992 (USEPA, 1992). This may be because very few groundwater samples have been analyzed for fosthiazate residues in the United States and because it has limited usa ge areas and crops. Fosthiazate w as not included in the suite of analyses conducted in the USEPA's National Survey of Pesticides in Drinking Water Wells26

(USEPA, 1990, 1992). Fosthiazate also is not included in the USGS NAQWA program. No surface water mo nitoring was located.

The California Department of Pesticide Regulation ( CDPR) surface water database ( http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm

, USGS NAWQA surface and ground water database ( http://infotrek.er.usgs.gov/apex/f?p=136:1:0::NO::: ), Pesticide Data Program ( http://www.ams.usda.gov/AMSv1.0/ams.fetchTemplateData.do?template=TemplateG&navID= &rightNav1=&topNav=&leftNav=ScienceandLaboratories&page=PDPDow nloadData/Reports& resultType=&acct=pestcddataprg ), and the USGS/EPA Reservoir Data Program (Blomquist et al., 2001) were evaluated for available monitoring data , however fosthiazate does not appear to be an analyte in these monitoring programs.

C. Ecological Effects Characterization

a) Aquatic Animals

The available acute toxicity data on fosthiazate (TGAI) indicate that it is highly toxic to freshwater invertebrates [EC 50 = 0.26 mg a.i./L (MRID 43916828)] and estuarine/marine invertebrates [LC 50 = 0.4 29 mg a.i./L (MRID 45540402)] ; slightly toxic to estuarine/marine fish [LC 50 = 46.5 mg a.i./L (MRID 45540403)] ; and practically n on

- toxic to freshwater fish [LC 50 = 111 mg a.i./L (MRID 43916826)] (see Table 3 ).

Chronic effects in the freshwater fish earl y life stage study using the fathead minnow ( Pimephales promelas ) included reduced dry weight and length of young fish (NOAEC = 2.32 mg a.i./L, LOAEC 4.48 mg a.i./L) (MRID 45540404). The freshwater invertebrate life

- cycle study determined a NOAEC value of 0.061 mg a.i./L and a LOAEC value of 0.128 mg a.i./L based on reduced number of offspring produced and parental mortality ( Daphnia magna ; MRID 43916829). No chronic toxicity data are available for estuarine/marine fish or invertebrates.

b) Aquatic Plants

A Tier I test with the green alga ( Selenastrum capricornatum ) found no adverse effects at a concentration equal to 4.5 mg a.i./L. There are no data available for vascular aquatic plants.

c) Terrestrial Animals

Birds

The available t oxicity data on fosthiaz ate (TGAI) indicate that it is highly toxic to birds on an acute [LD 50 = 10.6 mg a.i./kg

- bw (MRID 43916819)] and sub

- acute [LC 50 = 85 mg a.i./kg

- diet (MRID 41381106)] exposure basis

.
Both the mallard duck (

Anas platyrhynchos ) and bobwhite quail ( Colinus virginianus ) avian reproduction studies had the same NOAEC (21.7 mg a.i./kg

- diet) and LOAEC values (42.6 mg a.i./kg

- diet) (MRIDs 43916825 and 43916824, respectively). Significant effects on male and female weight gain, decreased eggshell thickness, and in creased cracked eggs were observed in the bobwhite quail.27

Mammals

The available acute toxicity data on fosthiazate (TGAI) indicate that it is moderately toxic to mammals [LD 50 = 51 mg a.i./kg

- bw (MRID 41347622)].

A 2

- generation rat study (see MRIDs 41381113 and 44414501) yielded a reproductive NOAEL of 10 mg a.i./kg

- diet (or 0.91 mg/kg/day for both males and females) and a LOAEL of 30 mg a.i./kg

- diet (equivalent to 2.09 and 2.60 mg/kg

- bw/day males and females, respectively) based on decreased viability index, litter size and pup weight for the f 1 generation.

Terrestrial Invertebrates

The acute contact honey bee ( Apis mellifera ) LD 50 is 0.247 μ g a.i./bee (MRID 41347636). Since the LD 50 is less than 2 μ g a.i./b ee, fosthiazate TGAI is categorized as highly toxic to bees on an acute contact basis.

d) Terrestrial Plants

Tier I and Tier II terrestrial plant toxicity tests were performed on technical fosthiazate in which dicots appear to be more sensitive than monocots . Based on a Tier II seedling emergence test on technical fosthiazate, the NOAEC and EC 25 for mustard are 0.8 and 1.0 lb a.i./A, respectively (MRID 43916839). Although the Tier I test results showed peppers were more sensitive (27 %) than mustard (<25 %) (MRID 43916837), no test was conducted with peppers. For Tier II vegetative vigor, the most sensitive terrestrial plant is the dicot buckwheat (NOAEC = 0.8 lb a.i./A; EC 25 = 3.3 lb a.i./A). Sorghum was the only monocot tested (NOAEC = 3.0 lb a.i./A and
t he EC 25 = > 6.0 lb a.i./A).28

IV. R ISK ESTIMATION

1. Non

- target Aquatic Animals and Plants

Because runoff and spray drift are not expected with the use of fosthiazate on tomatoes via drip irrigation under plastic mulch and previous assessments for fosthiazate that modeled higher application rates than assessed here found no LOC exceedances for aquatic organisms, risks to aquatic organisms are not expected. Exposure may occur via groundwater, but such exposure is expected to be less than previously assessed us es. Therefore, risks to aquatic animals are not quantitatively estimated.

2. Non

- target Terrestrial Animals

Screening

- level risk assessments do not typically evaluate risks to terrestrial invertebrates; however, toxicity information for beneficial insects is used to develop precautionary label language where necessary. Based on the available toxicity data alone , precautionary label language for bees is recommended for the fosthiazate labels

.

To estimate risks to soil

- dwelling invertebrates from direct application of fosthiazate, a concentration of 13.2 ppm is used as the estimated environmental concentration (EEC) (see the ‘Measures of Exposure’ section). The available contact LD 50 for honey bees is used as surrogate toxicity data for all arthropods ( i.e ., LD 50 = 0.247 μg a.i./bee ). Based on an average fresh weight per honey bee of 128 mg (Mayer and Johanse n, 1990), the contact LD 50 of honey bees (μg/bee) can be multiplied by 7.8 to convert the μg/bee value to a ppm value. This results in an LD 50 for bees of 1.9 ppm ( 0.247 μg a.i./bee x 7.8). Dividing the EEC (13.2 ppm) by the LD 50 (1.9 ppm) results in an RQ of 6.9, which exceeds the interim listed species LOC of 0.05 for terrestrial invertebrates.

For birds and mammals that may probe the soil for arthropod prey that are contaminated via the treated irrigation water, it is assumed that soil

- dwelling arthropods have a residue value of 1.7 ppm (see the ‘Measures of Exposure’ section). When 1.7 ppm is used as the residue on arthropods in T

- REX, acute dose

- based RQs for small and medium

- sized birds exceed the acute listed species LOC of 0.1 (RQs = 0.25 and 0.11, respectively), and dose

- based chronic RQs exceed the chronic LOC of 1 for small and medium m ammals (RQs = 1.48 and 1.26, respectively) (see Table 6 ).29

TABLE 6 . Acute and Chronic RQs for Birds and Mammals that Ingest Arthropods Contaminated with Fosthiazate (1.7 ppm) Via Treated Irrigation Water.
EXPOSURE TYPE BODY SIZE BIRDS MAMMALS Acute Chronic Acute Chronic

DOSE

- BASED RQs Small

[20 g (birds); 15 g (mammals)] 0.25

Not applicable 0.01 1.48

Medium [100 g (birds); 35 g (mammals)] 0.11 0.01 1.26

Large [1,000 g (birds and mammals)] 0.04 0.01 0.68

DIETARY

BASED RQs All sizes 0.02 0.08 Not applicable 0.17

Bolded numbers exceed an EPA Level of Concern (LOC)

. For birds and mammals that may eat earthworms, the earthworm fugacity model was used (based on maximum average soil concentrations estimated using PRZM). The avian and mammalian RQs are bounded based on two different K OC ’s and soil depths. The highest soil concentration (and the one resulting in the highest RQs) was based on a K OC of 25 and a soil depth of 1 cm; the lowest soil concentration was based on a K OC of 285 and a soil depth of 10 cm (see Table 7 ). The acute RQs for birds exceeded the listed species LOC for both modeled soil concentrations and the non

- listed species LOC for the highest soil concentration modeled (acute RQs ranged from 0.01 to 0.98). All of the chronic RQs for birds were <1. For mammals, none of the acute RQs exceeded any LOC; however the chronic LOC was exceeded for both modeled soil concentrations (RQs ranged from (0.11 to 5.71).

TABLE 7 . Acute and Chronic RQs for Birds and Mammal s that Ingest Earthworms Contaminated with Fosthiazate Via Treated Irrigation Water (Based on the Earthworm Fugacity Model)

. USING A SOIL CONCENTRATION BASED ON THE FOLLOWING: EXPOSURE TYPE BIRDS MAMMALS

Acute Chronic Acute Chronic

K OC = 285 Soil Depth = 10.0 cm DOSE

BASED RQs 0.20 N/A 0.01 1.16

DIETARY

BASED RQs 0.01 0.05 N/A 0.11

K OC = 25 Soil Depth = 1.0 cm DOSE

BASED RQs 0.98 N/A 0.06 5.71

DIETARY

BASED RQs 0.06 0.24 N/A 0.53
Bolded numbers exceed an EPA Level of Concern (LOC)

. For animals that may ingest treated tomato plants, a residue value of 0.32 ppm was used to model RQs for birds and mammals eating broadleaf plants in T

- REX (see the ‘Measures of Exposure’ section) . The only LOC exceeded is for listed 20 g birds (acute) (t he RQ is equal to the acute listed species LOC of 0.05) (see Table 8 ). No other RQ for birds or mammals that eat broadleaf plants (a cute or chronic) exceed an LOC.30

TABLE 8 . Acute and Chronic RQs for Birds and Mammals that Ingest Tomato Plants (Broadleaf Plants) Contaminated with Fosthiazate (0.32 ppm) Via Uptake from Treated Irrigation Water.
EXPOSURE TYPE BODY SIZE BIRDS MAMMALS Acute Chronic Acute Chronic

DOSE

- BASED RQs Small

[20 g (birds); 15 g (mammals)] 0.05

Not applicable <0.01 0.28

Medium [100 g (birds); 35 g (mammals)] 0.02 <0.01 0.24

Large [1,000 g (birds and mammals)] 0.01 <0.01 0.13

DIETARY

BASED RQs All sizes <0.01 0.01 Not applicable 0.03

Bolded numbers exceed an EPA Level of Concern (LOC)

.

There are no acute oral toxicity data available for honey bees and fosthiazate; therefore, risks to terrestrial invertebrates that may eat contaminated tomato plants cannot be quantified. Because fosthiazate can be used to suppress insects (according to current labels), it is as sumed that any insect that may feed on contaminated tomato plants is at risk of mor tality or other adverse effect

.

Risks to non

- target plants are not expected due to the relatively low toxicity (relative to the application rate) and the low exposure potential from the use of fosthiazate via drip irrigation under plastic mulch. Therefore, risks to plants are not quantitatively estimated.

3. Probit Slope Response Analysis of LOC Values and Acute RQ Values

The chance of individual effects for the taxa ass essed here using the IECv1.1.xls spreadsheet are provided in Table 9 . For all of the taxa, the default slope = 4.5 (upper and lower bound = 2 and 9)] was used to calculate the chance of mortality. The highest RQ for each taxon was used. If the highest R Q for a taxon did not exceed an acute LOC

, the acute listed species LOC was used to calculate the chance of effects. For birds, the chance of mortality (RQ = 0.98; slope = 4.5) is ~1 in 2 (or 50%); for mammals the chance of mortality at the acute listed s pecies LOC of 0.1 (slope = 4.5) is ~1 in 294,000; for terrestrial invertebrates, the chance of individual effects is 100% (RQ = 6.9; slope = 4.5); and for fish and aquatic invertebrates, the chance of mortality at the acute listed species LOC of 0.05 (slop e = 4.5) is ~1 in 418,000,000 (see Table 9 ).31

Table 9. Chance of Individual Effects for Fosthiazate Use on Tomatoes

.

TAXON ACUTE RQ or LOC SLOPE CHANCE OF INDIVUAL EFFECTS

Birds RQ = 0.98 4.5 ~1 in 2.07

2 ~1 in 2.03

9 ~1 in 2.13

Mammals LOC = 0.1 4.5 ~1 in 294,000 2 ~1 in 44.0 9 ~1 in 8.86E+18

Terrestrial Invertebrates RQ = 6.9 4.5 ~1 in 1.0 2 ~1 in 1.05 9 ~1 in 1.0
Fish (Freshwater and Estuarine/ Marine) LOC = 0.05 4.5 ~1 in 418,000,000 2 ~1 in 216 9 ~1 in 1.75E+31
Aquatic Invertebrates (Freshwater and Estuarine/ Marine) LOC = 0.05 4.5 ~1 in 418,000,000 2 ~1 in 216 9 ~1 in 1.75E+31

V. R ISK DESCRIPTION

Based on the available data and the registered use pattern for fosthiazate ( i.e ., drip irrigation to tomatoes under plastic mulch), off

- site transport is not expected; therefore, risks to aquatic organisms are not expected based on the low potential of exposure in aquatic environments and the results of previous assessments . Furthermore, risks to terrestrial plants are not expected due to the low potential for exposure and the results of previous risk assessments

. Risks, however, are expected for terrestrial invertebrates [both soil

- dwelling (from direct exposure) and non

- soil

- dwelling (from ingestion of treated
tomato plants)] and federally

- listed birds (acute) and listed and non

- listed mammals (chronic) from the ingestion of contaminated terrestrial invertebrates (including earthworms). Risks to birds (and, thus, reptiles and terrestrial

- phase amphibians) and mammals from the ingestion of contaminated tomato plants are expected to be minimal. Therefore, the risk hypothesis is supported: Fosthiazate, when used in accordance with current labels, can result in exposure to non

- target terrestrial animals. Exposure via d irect applications (soil

- dwelling invertebrates) and/or via ingestion of part(s) of the treated tomato plant may be above levels where adverse effects upon the survival, growth, and reproduction of non

- target terrestrial animals (including federally

- listed threatened and endangered species) would occur (see below for the discussion on listed species)

. The only registered use for fosthiazate is for tomatoes under plastic mulch via drip irrigation. Therefore, offsite transport from spray drift, runoff, an d leaching to groundwater are expected to be minimal. For aquatic organisms ( i.e ., aquatic vertebrates, invertebrates, and plants), no LOCs were exceeded in previous risk assessments for broadcast fosthiazate uses with higher application rates than assessed here. Additionally, because of the low potential for off

- site exposure and re lative insensitivity of terrestrial32

plants to fosthiazate, risks to terrestrial plants are not expected from the registered fosthiazate use on tomatoes. Therefore, although not quantitatively assessed, risks to aquatic organisms and terrestrial plants are not expected from the use of fosthiazate on
tomatoes.

For terrestrial vertebrates that may ingest tomato plants in which fosthiazate has been translocated, the only RQ that approaches an LOC is the dose

- based acute RQ for listed, small birds (the RQ = 0.05). No other RQs (for vertebrates that may eat plants) approach or exceed any LOC. Because the EECs are expected to be conservative [due to the assumptions made in the modeling ( e.g ., u sing the lower end of the range of plant weight and a lower bound number of plants per acre)], and the fact that the LOC does not exceed but instead matches the LOC, actual risks to listed birds that may ingest treated tomato plants are not expected.

There is, however, a potential for risk to birds (and, thus, reptiles and terrestrial

- phase amphibians) and mammals that ingest terrestrial invertebrates contaminated with fosthiazate on the site of application. Based on T

- REX and an EEC of 1.7 ppm for co ntaminated arthropods, the dose

- based RQs for small and medium size birds exceed the acute listed species LOC [RQs = 0.25 (20g bird) and 0.11 (100g bird)]. Additionally, the chronic, dose

- based RQs for small and medium size mammals exceed the chronic risk LOC [RQs = 1.48 (15g mammal) and 1.26 (35g mammal)]. No other RQs based on t he T

- REX analyses exceed any LOCs. Similar results were found for birds and mammals that eat contaminated earthworms (acute RQs for birds ranged from 0.01 to 0.98; chronic RQs f or mammals ranged from (0.11 to 5.71).

In addition to risks to birds, reptiles, terrestrial

- phase amphibians, and mammals that eat terrestrial invertebrates, there are potential direct risks to terrestrial invertebrates from the use of fosthiazate on toma toes. Screening

- level risk assessments do not typically evaluate risks to terrestrial invertebrates; however, toxicity information for beneficial insects is used to develop precautionary label language where necessary. Based on the available toxicity dat a [LD 50 = 0.247 μg a.i./bee (contact)] and the systemic nature of fosthiazate , precautionary label language for bees is recommended for the fosthiazate labels.

For listed terrestrial invertebrates, risks to soil

- dwelling invertebrates found on the site of application are expected (RQ = 6.9; this RQ exceeds the interim listed species LOC for terrestrial invertebrates of 0.05). Additionally, although not quantifiable due to a lack of oral toxicity data for invertebrates, risks to listed terrestrial invert ebrates that may ingest tomato plant parts in which fosthiazate has been translocated are expected. This is based on the contact toxicity data for honey bees, the systemic nature of fosthiazate and label information that states that fosthiazate can be use d to suppress insects; it is, therefore, assumed that any insect that may feed on contaminated tomato plants is at risk of mortality or other adverse effect ( i.e ., risk is assumed).33 1. Review of Incident Data

Reviews of the Ecological Incident Informatio n System (EIIS, version 2.1), the Avian Incident Monitoring System (AIMS) 2 , and the Incident Data System (IDS) were conducted on August 13, 2012. There were no reported ecological incidents associated with fosthiazate. Because ecological incident data are not systematically collected, an absence of reported incidents should not be construed as the absence of incidents.

2. Assumptions and Limitations

a) As required by FIFRA and the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicit y. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex rati os in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of the Preliminary Problem Formulation for Registration Re view (DP Barcode D360360 ), EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), fosthiazate is subject to the endocrine sc reening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP employs a two

- tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to iden tify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any adverse endocrine

- related effects caused by the substance, and establish a dose

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Fosthiazate is not among the group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. Accordingly, as part of registration review, EPA w ill issue future EDSP orders/data call

- ins, requiring the submission of EDSP screening assays for

2 http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/login.cfm ?CFID=113048231&CFTOKEN=924348234

fosthiazate . For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/ ).

b) The primary uncertainties for this risk assessment are related to the fosthiazate use pattern ( i.e ., application via drip irrigation to tomatoes under plastic mulch) and the systemic nature of the chemical. Because limited off

- site exposure is expected from this use pattern, the focus of concern for risks is on the site of application. The primary routes of exposure to non

- target org anisms is expected to be via direct application (to soil

- dwelling invertebrates), ingestion of contaminated soil

- dwelling invertebrates (by terrestrial invertebrates), and ingestion of tomato plant parts in which fosthiazate has been translocated (by terre strial vertebrates and invertebrates). There are currently no standard methods for assessing exposure or risk to soil

- dwelling invertebrates (or things that might eat them) or exposure or risk from systemic pesticides. Therefore, attempts were made to c onservatively quantify risk whenever possible ; however

, there is uncertainty regarding the non

- standard methods used. The assumptions made to model exposures were largely based on label information ( e.g ., the amount of water used to water in fosthiazate) and data from the open literature ( e.g ., the amount of chemical that is translocated through the treated plants and the weight of tomato plants). Changes in any of these assumptions have the potential to alter the risk conclusions. Additionally, there is a potential for some organisms ( e.g ., amphibians) to be attracted to the use sites

– i.e ., the dark, moist areas under the plastic mulch. The potential preferential use of such sites is beyond the scope of this assessment

Because most of the RQs calcula ted for birds and mammals are close to the LOCs for
acute or chronic exposure , some additional modeling was done to see how different use assumptions would impact the RQs for birds and mammals that may eat contaminated terrestrial invertebrates

. The RQs i n this assessment , using T

- REX, are based on a maximum application rate (1.5 lb a.i./acre) and the minimum recommended amount of irrigation water (0.5 inch of water per acre), since this results in the highest concentration of fosthiazate in irrigation water. However, the concentration of fosthiazate in irrigation water could be reduced by increasing the amount of water used per acre (the label states 0.5 to 1.0 inches of irrigation water per acre should be used) and/or by reducing the application rate.

For birds, using T

- REX, the co ncentration of fosthiazate in irrigation water would need to be ≤5.16 ppm for none of the RQs for birds that eat insects to exceed an Agency LOC [a concentration of 5.16 ppm in irrigation water would result in an arthropod concentration of 0.66 ppm; i.e., 5.16 ppm x 0.128 (the weight of a surrogate honey bee)]. Therefore, any increase in the amount of irrigation water used and/or a decrease in the application rate that would result in concentrations of fosthiazate ≤5.16 ppm would lead to no LOC exceedances for birds using T

- REX. The concentration of fosthiazate in irrigation water was calculated for various amounts of irrigation water used and application rates (see Table 10 ). Based on this analysis, if the application rate was reduced to 1.0 lb a.i./acre and was applied using 1 inch of irrigation water/acre, no bird LOCs would be exceeded using T

- REX. If 0.5 inches of irrigation water were used per acre, the application rate35

would need to be reduced to

~ 0.5 lb a.i./acre for no bird LOCs to be exceeded us ing T

REX

.

Table 10. Estimated Concentratoins (in ppm) of Fosthiazate in Irrigation Water Based on Various Amounts of Water Used and Application Rates.
AMOUNT OF IRRIGATION WATER/ACRE (in inches) APPLICATION RATE/ACRE

0.5 lb (226,796 mg) 0.75 lb

(34 0,194 mg) 1.0 lb

(453,592 mg) 1.25 lb

(566,991 mg) 1.5 lb

(680,389 mg)

0.5 (51,395 L) 4.41 6.62 8.83 11.03 13.24 0.75 (77,093 L) 2.94 4.4 5.88 7.35 8.83 1.0 (102,790 L) 2.21 3.31 4.41 5.52 6.62

For mammals, using T

- REX, the concentration of fosthiazate in irrigation water would need to be ≤8.83 ppm for none of the RQs for mammals that eat insects to exceed an Agency LOC [a concentration of 8.83 ppm in irrigation water would result in an arthropod concentration of 1.13 ppm; i.e., 8.83 ppm x 0.128 (the weight of a surrogate honey bee)]. At an application rate of 1.5 lb a.i./acre, no mammal LOCs would be exceeded using T

- REX if ≥0.75 inches of irrigation water were used per acre (see Table 10 ). If 0.5 inches of irrigation water were used per acre, the application rate would need to be reduced to 1.0 lb a.i./acre for no mammal LOCs to be exceeded using T

- REX.

For birds and mammals that may eat contaminated earthworms specifically, there were some LO C exceedances at the maximum fosthiazate application rate (1.5 lb a.i./acre) using the Earthworm Fugacity model (see Table 7 ). The RQs calculated using the Earthworm Fugacity model have a linear relationship with the application rate. Therefore, to deter mine an application rate that would result in an RQ that no longer exceeds an LOC, the RQ is divided by the LOC; the application rate can th e n be divided by that number to estimate the application rate that no longer exceeds an LOC ( i.e

., RQ/LOC = x; 1.5 l b a.i./acre ÷ x = the application rate that no longer exceeds the LOC).

The results of the fugacity model were bound by different K OC and soil depths. Using a K OC of 285 and a soil depth of 10 cm resulted in an acute RQ for birds of 0.20. Therefore, using this K OC and soil depth, the application rate would need to be ≤ 0.75 lb a.i./acre for the RQ not to exceed the listed species LOC for birds [0.20 (RQ)/0.10 (LOC) = 2; 1.5 lb a./acre ÷ 2 = 0.75 lb a.i./acre]. With a K OC of 25 and a soil depth of 1 cm, the application rate would need to be ≤ 0.15 lb a.i./acre for the RQ not to exceed the listed species LOC for birds using the Earthworm Fugacity model [0.98 (RQ)/0.10 (LOC) = 9.8; 1.5 lb a.i./acre ÷ 9.8 = 0.15 lb a.i./acre].

For mammals and a K OC of 285 and a soil depth of 10 cm, the application rate would need to be ≤ 1.3 lb a.i./acre for the RQ to not exceed the chronic LOC for mammals using the Earthworm Fugacity mo del [1.16 (RQ)/1 (LOC) = 1.16; 1.5 lb a.i./acre ÷ 1.16 = 0.15 lb a.i./acre ]. With a K OC of 25 and a soil depth of 1 cm, the application rate would need to be ≤ 0.26 lb a.i./acre for the RQ not to exceed the listed species LOC for mammals [5.71 (RQ)/1 (LOC ) = 5.71; 1.5 lb a.i./acre ÷ 5.71 = 0.26 lb a.i./acre].36

c) Birds a re used as surrogate species for reptiles and terrestrial

- phase amphibians

. Terrestrial

- phase amphibians and reptiles are poikilotherms ( their body temperature varies with environmental temper ature ) . Birds are homeotherms ( their temperature is regulated, constant, and largely independent of environmental temperatures). As a consequence, the caloric requirements of terrestrial

- phase amphibians and reptiles are markedly lower than birds. There fore, on a daily dietary intake basis, birds consume more food than terrestrial

- phase amphibians and reptiles

.

The T

- HERPS model is used to allow for further characterization of dietary exposures of terrestrial

- phase amphibians and reptiles relative to birds ( T

- HERPS is available at: http://www.epa.gov/oppefed1/models/terrestrial/index.htm )

. To quantify the potential risk for listed terrestrial

- phase amphibians and reptiles that may eat contaminated terrestrial invertebrates , food intake equations for the iguanid lizard in T

- HERPS a re used to replace the food intake equation in T

- REX for birds. Unlike T

- REX, T

- HERPS has not been updated to include estimated residues on arthropods as a single dietary item; instead T

- HERPS includes ‘small insect’ and ‘large insect’ dietary categories. F or the purposes of this analysis, since the estimated residues on terrestrial invertebrate food items are based on the concentration of fosthiazate in the irrigation water used during application (instead of estimated residues based on a foliar application), input parameters that resulted in residues of 1.7 ppm on ‘small insects’ ( i.e ., 0.0126 lb a.i./acre application rate; one application; 35

- day defaul t foliar half

- life ; Upper Bound Kenaga values ) were used for calculating RQs

. Based on this analysis, none of the RQs for amphibians or reptiles that eat terrestrial invertebrates exceed an Agency LOC (acute RQs range from <0.01 to 0.02; the chronic RQ is 0.08). This indicates a low potential for risk to insectivorous terrestrial

- phase amphibians or reptiles from the use of fosthiazate on tomatoes. Currently, the Earthworm Fugacity model does not calculate RQs for terrestrial

- phase amphibians or reptiles that eat contaminated earthworms. Therefore, the potential risk to terrestrial

- phase amphibians or reptiles that specifically eat earthworms is uncertain.

d) There are no toxicity data for fosthiazate available from a fish life

- cycle study. Additionally, data are only available for one of the four species of aquatic non

- vascular plants typically tested. However, data from such studies would not be expected to alter the risk conclusions for aquatic organisms from fosthiazate use on tomatoes using drip irr igation due to the limited potential for off

- site exposure.

e) Based on its mode of action and target pests, the risks to terrestrial invertebrates are more certain than the potential risks to terrestrial vertebrates that consume contaminated arthropods and/or plants. However, based on the available information, there is a potential risk to terrestrial invertebrates ; listed and non

- listed birds (acute) listed and

non

- listed mammals (chronic) that eat arthropods (including earthworms); and terrestrial

phase amphibians and reptiles that specifically eat earthworms

.37

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- 0017

- BE

- 000. Unpublished study prepared by Ricerca, Inc. 166 p.

43916840 Crosby, K. (1995) Effect of IKI 1145 on Vegetative Vigor of Plants (Tier II): Lab Project

Number: 6362

- 95

- 0018

- BE

- 001: 95

- 0018: 6362

- 95

- 0018

- BE

- 000. Unpublished study prepared by Ricerca, Inc. 122 p.

41347636 Hoxter, K. (1989) An Acute Contact Toxicity Study wit h the Honey Bee: IKI

- 1145 Technical:

Lab Project Number: 272

- 101B. Unpub

- lished study prepared by Wildlife International Ltd. 16 p.

MRIDs

– Environmental Fate:

47223201 Shimura, T. (2007) Product Chemistry Studies for Fosthiazate 75%EC. Project

Number: 1145FI/0706101, 92944653. Unpublished study prepared by Ishihara Sangyo Kaisha, Ltd. 43 p.

47223201 Shimura, T. (2007) Product Chemistry Studies for Fosthiazate 75%EC. Project

Number: 1145FI/0706101, 92944653. Unpublished study prepared by Ishihar a Sangyo Kaisha, Ltd. 43 p.

47223201 Shimura, T. (2007) Product Chemistry Studies for Fosthiazate 75%EC. Project

Number: 1145FI/0706101, 92944653. Unpublished study prepared by Ishihara Sangyo Kaisha, Ltd. 43 p.

41347637 Kato, Y. (1987) IKI

- 1145: Hydroly sis in Buffer Solutions at PH 5, 7, and 9: Lab

Project Number: I

- 221. Unpublished study prepared by Ishihara Sangyo Kaisha Ltd. 34 p.

43916831 Huhtanen, K.; Lentz, N. (1993) A Photolysis Study of Fosthiazate (IKI

- 1145) in

Water at pH 5: Lab Project Number: 5287

- 92

- 0153

- EF

- 001: 92

- 0153: 5287

- 92

- 0153

- EF

- 000. Unpublished study prepared by Ricerca, Inc. 106 p.

43916832 Walsh, K.; Huhtanen, K. (1995 ) An Aerobic Soil Metabolism Study with IKI

- 1145

(Fosthiazate): Lab Project Number: 3378

- 89

- 0384

- EF

- 001

- 001: 89

- 0384. Unpublished study prepared by Ricerca, Inc. 293 p.

43916833 Hatzenbeler, C. (1995) An Anaerobic Aquatic Soil Metabolism Study with ((car bon

14)

- T)

- IKI

- 1145 and ((carbon 14)

- B)

- IKI

- 1145: Lab Project Number: 5163

- 92

- 0023

- EF

- 001: 92

- 0023: IKI

- 1145. Unpublished study prepared by Ricerca, Inc. 123
p.41

47098903 Hatzenbeler, C. (1996) [14

- Carbon

- B]IKI

- 1145: Degradation and Fate in

Water/Sediment System. Project Number: 6214/94/0186/EF/001. Unpublished study prepared by Ricerca, Inc. 120 p.

41347639 Kato, Y. (1988) IKI

- 1145: Adsorption and Desorption in Soils: Lab Project

Number: I

- 231. Unpublished study prepared by Ishihara Sangyo Kaisha Ltd. 33 p.
41347640 Arita, H. (1989) IKI

- 1145: Mobility of Parent Compound and Its De

- gradation

Products in Soil Columns: Lab Project Number: I

- 228. Unpublished study prepared by Ishihara Sangyo Kaisha Ltd. 43 p.

43916835 Jablonski, J. (1995) Terrestrial Fie ld Dissipation of Fosthiazate Applied to

Bareground Near Camilla, Georgia (Bridging Report: Effect of Formic Acid on Extraction of Residues): Lab Project Number: 5288

- 92

- 0159

- CR

- 005: 92

- 0159: ISK

- 1992

- 501

- 03. Unpublished study prepared by Ricerca, Inc. 218 p.

43952901 Jablonski, J. (1995) Terrestrial Dissipation of Fosthiazate Applied to Bareground

Near Ridgefield, Washington: Lab Project Number: 92

- 0159: 5288

- 92

- 0159

- CR

001: ISK

- 1992

- 501

- 00. Unpublished study prepared by Ricerca, Inc. 365 p.

43952902 Jablonski, J.; McFall, D. (1995) Terrestrial Dissipation of Fosthiazate Applied to

Bareground Near Madera, California: Lab Project Number: ISK

- 1992

- 501

- 01: ISK

1992

- 501

- 00: 92119. Unpublished study prepared by Ricerca, Inc. 371 p.

43952903 Jablonski, J. (1995) Terrestrial Dissipation of Fosthiazate Applied to Bareground

Near Camilla, Georgia: Lab Project Number: 92

- 0159: ISK

- 1992

- 501

- 03: ISK

1992

- 501

- 00. Unpublished study prepared by Ricerca, Inc. 507 p.

43952904 Jablonski, J. (1995) Terrestrial Dissipa tion of Fosthiazate Applied to Bareground in

Lucama, North Carolina: Lab Project Number: 92

- 0159: 5288

- 92

- 0159

- CR

- 004: 5288

- 92

- 0159

- CR

- 000. Unpublished study prepared by Ricerca, Inc. 407 p.

41347642 Fackler, P. (1989) IKI

- 1145: Bioconcentration and Elimination of ?Carbon 14|

-

residues by Bluegill (Lepomis macrochirus): Lab Pro

- ject Number: 89

- 11

- 3157. Unpublished study prepared by Spring

- born Laboratories, Inc. 38 p.

47223201 Shimura, T. (2007) Pro duct Chemistry Studies for Fosthiazate 75%EC. Project

Number: 1145FI/0706101, 92944653. Unpublished study prepared by Ishihara Sangyo Kaisha, Ltd. 43 p.

43916800 ISK Biosciences Corp. (1996) Submission of Product Chemistry, Toxicology,

Residue, Hazard to Non

- Target Organisms, and Environmental Fate Data in Support of the Application for Registration of Fosthiazate Technical. Transmittal of 41 Studies.

47098902 Doran, T. (2007) Environmental Fate Assessment for Fosthiazate:

GroundWater/Drinking Water Mode ling Estimates. Project Number: 06/001/ISK. Unpublished study prepared by North Coast Regsci, LLC. 28 p.42

APPENDIX C. Sample Inputs and Outputs for the Earthworm Fugacity Model

Use of fugacity approach to estimate exposures to small mammals consuming ea rthworms contaminated with pesticides

.

The T

- REX model (USEPA

, 2008) is useful for assessing exposures of terrestrial animals to pesticide residues on foliar surfaces of crops and seeds. The model cannot be used to assess pesticide exposures to terrestrial animals resulting from consumption of earthworms contaminated with pesticide mass present in the soil of the application site. In order to explore the potential exposures of mammals and birds to pesticides in the soil and earthworms on the treatment site, a simple fugacity approach can be employed to estimate concent rations of the pesticide of interest earthworms.

Fugacity is most often regarded as the "escaping tendency" of a chemical from a particular phase. Fugacity (F) has units of pressure, generally pascals (Pa), and can be related to phase concentrations. Fo r any particular environmental phase ( e.g., water, soil, air, or biota) there is a corresponding "fugacity capacity" with units of mol/m 3

- Pa and is denoted by Z. The relationship between fugacity, fugacity capacity and chemical concentration (C) is define d by Equation 1.

Fugacity capacities for a given chemical are calculated for the phases of interest as part of the exposure point estimation methodology (Mackay and Paterson 1981). The following calculations of fugacity capacities for soil (Z S ) and earthworms (Z E ) (Equations 2 and 3, respectively) require several chemical

- specific parameters and assumptions of system temperature (25 o C) and steady state equilibrium. Parameter values relevant to Equations 2 and 3 are defined in Table 1.

Fugacity capacities for a given chemical are calculated for the phases of interest as part of the exposure point concentration estimation methodology. By definition, the ratio between Z values of different phases (compartments) equals the partitioning coefficient ( e.g., Equation 4).

In this approach, it is assumed that a pesticide partitions between the soil, the (pore) water and the air contained within the soil of the treatment site. It is assumed that earthworms dwelling within the soil are exposed to a pesticide via ingestion of c ontaminated soil. The concentration43

of a pesticide in earthworm tissues can be calculated according to Equation 5 (see Table 1 for parameter definitions).

Table 1. Summary of parameters relevant to earthworm fugacity model. Symbol Definition Units
C E Chemical concentration in earthworm tissue mol/m 3

C E ' Chemical concentration in earthworm tissue g/kg

C S Chemical concentration in soil mol/m 3

H Henry’s Law constant m 3

- Pa/mol

K d Soil partitioning coefficient cm 3 /g

K OW Octanol to water partition coefficient none
L Lipid fraction of earthworm none
MW molecular weight of chemical g/mol

Z E Fugacity capacity of pesticide in earthworms mol/m 3

- Pa

Z S Fugacity capacity of pesticide in soil mol/m 3

- Pa

ρ E density of earthworm kg/m 3

ρ S Bulk density of soil g/cm 3

Equation 5 can be redefined using equations 2 and 3 as follows in Equation 6. Equation 6 is used to calculate the concentration of a pesticide in earthworms inhabiting the soil of treatment sites.

C S is intended to be representative of the steady

- state concentrations of the pesticide of interest in soil. This value is calculated using PRZM. Kd and Kow are chemical

- speci fic parameters. Kd should be consistent with the value input into PRZM. ρ S is dependant upon the soil properties of the selected PRZM scenario used to derive C S . L is based on the lipid content of earthworms, which was assumed to be 0.01 (Cobb et al. 1995 ). The resulting C E value is in units of mol/m 3

. This value is converted to units of g/kg using equation 7. The density of the earthworm (ρ E ) is assumed to be 1000 kg/m 3 (equivalent to density of water).44

MODEL INPUTS AND OUTPUTS:
Characteristics of Fosthiazate. Parameter (symbol) Value Units Pesticide Name Fosthiazate none Molecular weight (MW) 283.36 g/mol Octanol

- water Partition Coefficient (Kow) 194 none Soil partition coefficient (Kd) 1.789 cm 3 /g

Soil parameters. Parameter (symbol) Value Units Bulk density of soil (ρs)* 1.30 g/cm 3 Concentration of pesticide in soil (estimated using PRZM) 6.3 g/m 3
Concentration of Fosthiazate in soil (Cs) 2.22E

- 02 mol/m 3

Earthworm parameters. Parameter (symbol) Value Units Lipid fraction of earthworm (L) 0.01 none Water fraction of earthworm (W) 0.84 none Density of earthworm (ρE) 1000 kg/m 3
Concentration of Fosthiazate in earthworm (CE) 1.86E

- 02 mol/m 3 Concentration of Fosthiazate in earthworm (CE') 0.005 g/kg* *equivalent to mg/g

Mammalian toxicity data for Fosthiazate. Endpoint/Parameter (symbol) Value Units
Acute oral LD 50 51 mg/kg

- bw Body weight of acute test animal* (TW) 350 g Chronic NOAEL 0.5 mg/kg

- bw Chronic NOAEC 10 mg/kg

- diet Body weight of chronic test animal* (TW) 350 g Body weight of assessed animal (AW) 15 g Food intake of assessed animal (F) 17.9 g/day Body weight normalized food intake of assessed animal (F N ) 1192 g/kg

- bw

- day
*For rats, the default body weight is 350 g, if no other data are available.

Avian toxicity data for Fosthiazate. Endpoint/Parameter (symbol) Value Units
Acute oral LD 50 10.6 mg/kg

- bw Body weight of test animal for LD 50 * (TW) 178 g Subacute dietary LC 50 85 mg/kg

- diet
Chronic NOAEC 21.7 mg/kg

- diet Mineau Scaling Factor** 1.15 none Body weight of assessed animal (AW) 20 g Food intake of assessed animal (F) 28.47 g/day Body weight normalized food intake of assessed animal (F N ) 1424 g/kg

- bw

- day45

*Unless study specific data are available: For bobwhite quail, assume 178 g. For mallard duck, assume 1580 g. **Default value is 1.15. Consult Mineau et al. (1996) to obtain pesticide specific values.

Mammalian and avian risk quotients for Fosthiazate. Endpoint EEC Toxicity Value RQ Mammalian, acute dose

- based 6.28 112.1 0.06 Mammalian, chronic dose

- based 6.28 1.1 5.71 Mammalian, chronic dietary

- based 5.27 10.0 0.53 Avian, acute, dose

- based 7.50 7.6 0.98 Avian, acute, dietary

- based 5.27 85.0 0.06 Avian, chronic, dietary

- based 5.27 21.7 0.24

References:

Cobb, G.P., E.H. Hol, P.W. Allen, J.A Gagne, R.J. Kendall. 1995. Uptake, metabolism, and toxicity of terbufos in the earthworm ( Lumbricus terrestris ) exposed to COUNTER

- 15G in artificial soils. Environ. Toxicol. Chem. 14(2):279

- 285.

Mackay, D. and S. Paterson. 1981. Calculating fugacity. Environ. S ci. Technol. 15: 1006

- 1014.

U

. S

. EPA. 2008. User’s Guide: T

- REX Version 1.4.1 (Terrestrial Residue Exposure model). United States Environmental Protection Agency. Environmental Fate and Effects Division. http://www.epa.gov/oppefed1/models/terrestrial/index.htm#trexAPPENDIX D: ECOTOX Run

O pen literature studies identified using EPA’s ECOTOXicology database ( ECOTOX) ( USEPA, 2007 c ), which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife.

Papers that Were Accepted for ECOTOX

Buhler, W. G., Brust, G. E., & Foster, R. E. Control of Striped Cucumber Beetle on Canta loupe in Vincennes, IN, 1993. Arthropod Manag.Tests 19, 77

- 78 (28E). 1994. SOIL,ENV. Notes: EcoReference No.: 105074 Chemical of Concern: FTZ,CBF,DZ,ES,IMC,CBL,PMR,EFV,BFT

Grove, I. G., Woods, S. R., & Haydock, P. P. J. Toxicity of 1,3

- Dichloropropene an d Fosthiazate to Wireworms (Agriotes spp.). Ann.Appl.Biol. 137[1], 1

- 6. 2000. SOIL,ENV. Notes: EcoReference No.: 93662 Chemical of Concern: EP,FTZ,13DPE

Lin, K., Zhang, F., Zhou, S., Liu, W., Gan, J., & Pan, Z. Stereoisomeric Separation and Toxicity of t he Nematicide Fosthiazate. Environ.Toxicol.Chem. 26[11], 2339

- 2344. 2007. WATER,AQUA. Notes: EcoReference No.: 105106 Chemical of Concern: FTZ

Power, K. T., Shetlar, D. J., Niemczyk, H. D., & Belcher, M. G. Control of Billbug Larvae and a Subsequent Whit e Grub Population on a Lawn Area in Wayne County, Ohio, 1993. Arthropod Manag.Tests 19, 324 (55G). 1994. ENV,SOIL. Notes: EcoReference No.: 104171 Chemical of Concern: FTZ,IMC

Semtner, P. J. & Wilkinson, W. B. Cutworm and Flea Beetle Control on Flue

- Cure d Tobacco, 1994. Arthropod Manag.Tests 20, 257

- 258 (135F). 1995. SOIL,ENV. Notes: EcoReference No.: 104170 Chemical of Concern: FTZ,CPY,ACP

Target Papers

Giannakou, I. O., Karpouzas, D. G., Anastasiades, I., Tsiropoulos, N. G., & Georgiadou, A. Factors Affecting the Efficacy of Non

- Fumigant Nematicides for Controlling Root

- Knot Nematodes. Pest Manag.Sci. 61[10], 961

- 972. 2005. SOIL,TOP,ENV. Notes: EcoReference No.: 86817 Chemical of Concern: OML,FTZ,FMP,CDF

McKenzie, C. L., Cartwright, B., Damicone, J ., & Jackson, K. Evaluation of Soil Insecticides for Early Season Control of Thrips on Peanuts, 1993. Arthropod Manag.Tests 19, 104

- 105 (62E). 1994. SOIL,ENV. Notes: EcoReference No.: 104176 Chemical of Concern: FTZ,ADC,FMP

Rich, J. R., Dunn, R. A., Thom as, W. D., Breman, J. W., & Tervola, R. S. Evaluation of Fosthiazate for Management of Meloidogyne javanica in Florida Flue

- Cured Tobacco. J.Nematol. 26[4 Suppl.], 701

- 704. 1994. SOIL,ENV. Notes: EcoReference No.: 93865 Chemical of Concern: FTZ,FMP,13DPE47 Papers Not Acceptable for ECOTOX

Gilreath, J. P., Jones, J. P., Santos, B. M., & Overman, A. J. Soil Fumigant Evaluations for Soilborne Pest and Cyperus rotundus Control in Fresh Market Tomato. Crop Prot. 23[10], 889

- 893. 2004. SOIL,ENV,MIXTURE. Notes: EcoReference No.: 77512 Chemical of Concern: MTAS,DZM,CLP,FTZ,PEB,MB,CLPM