### 2 of 43 

# Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Assessmentsin Support of the Registration Review of Fenbutatinoxide

Bis [tris (2-methyl-2-phenylpropyl) tin] oxide. (Fenbutatin-oxide CAS 13356-08-6)

Prepared by: Charles Peck, Fate Scientist Anita Pease, Senior Biologist

Reviewed by: Thomas Steeger, Senior Biologist Marietta Echeverria, Senior Scientist Elizabeth Behl, Branch Chief U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division
Environmental Risk Branch IV

1200 Pennsylvania Ave., NW
Mail Code 7507P Washington, DC 20460



### September 28, 2009

### 3 of 43 Table of Contents

1. Purpose.........................................................................................................4
2. Problem Fo rmulation ........................................................................................................ ..........4 2.1. Nature of Regulatory Action............................................................................................... . 4
2.2. Previous Risk Assessments................................................................................................. . 4
3. Stressor Source and Distribution ............................................................................................ .....6
3.1. Mechanism of Action....................................................................................................... .... 6 3.2. Overview of Pesticide Usage............................................................................................... 6 3.3. Environmental Fate and Transport....................................................................................... 8 4. Receptors...................................................................................................10 4.1. Effects to Aquatic Organisms ............................................................................................ 12 4.2. Effects to Terrestrial Organisms ........................................................................................ 13 4.3. Effects of Degradates..................................................................................................... .... 13
4.4. Incident Database Review.................................................................................................. 14 4.5. Ecosystems Potentially at Risk .......................................................................................... 14 5. Assessment Endpoints ........................................................................................................ .......15 6. Conceptual Model........................................................................................................... ..........15 6.1. Risk Hypothesis ........................................................................................................... ...... 15 6.2. Conceptual Diagram ........................................................................................................ .. 16 7. Analysis Plan .............................................................................................................. ..............18
7.1. Stressors of Concern ...................................................................................................... .... 19 7.2. Measures of Exposure...................................................................................................... .. 19
7.3. Measures of Effect ........................................................................................................ ..... 21 7.4. Integration of Exposure and Effects .................................................................................. 22
7.5. Deterministic and Probabilistic Assessment Methods....................................................... 22 7.6. Endangered Species Assessments...................................................................................... 22 7.7. Drinking Water Assessment .............................................................................................. 23 7.8. Preliminary Identification of Data Gaps............................................................................ 23

7.8.1. Fate.................................................................................................................... .......... 23
7.8.3. Effects ................................................................................................................. ........ 24
8. References................................................................................................................. ................28

Appendix A. Fenbutatin-oxide and Degradates.............................................................................34 Appendix B. Data Call-In Tables................................................................................................ ...35 Appendix C. Summary of Previous Assessments..........................................................................42

### 4 of 43 1. Purpose

The purpose of this problem formulation is to pr ovide an understanding of what is known about the environmental fate and ecological effects of the registered uses of fenbutatin-oxide, also
known as Vendex ® 

### . Fenbutatin-oxide is a non-systemic, restricted use, organotin acaricide registered for use against mites on a variety of agricultural, orchard, and ornamental use sites. Its two end-use products, Vendex ® 

### 50 WP and ProMITE ® 

### 50WP, are formulated as a wettable powder and as dispersable granules, respectiv ely, and are applied post-emergence via ground, aerial, or orchard airblast applic ation when mites first appear. Th is document will provide a plan for analyzing data on fenbutatin-oxide and for c onducting relevant environmental fate, ecological risk, endangered species and drin king water assessments for its re gistered uses. Additionally, this problem formulation is intended to identify data gaps, uncertainties, a nd potential assumptions
used to address those uncertainties relative to characterizing the ecological risk associated with the registered uses of fenbutatin-oxide.

2. Problem Formulation

2.1. Nature of Regulatory Action

Under the Federal Insecticide, F ungicide, and Rodenticide Act (FIF RA), all pesticid es distributed or sold in the United States ge nerally must be registered by EPA. In determining whether a pesticide can be registered in the U.S., EPA eval uates its safety to non-target species based on a wide range of environmental a nd health effects studies. In 1996, FIFRA was amended by the Food Quality Protection Act, and EPA was mand ated to implement a new program for the periodic review of pesticides, i.e ., Registration Review ( http://www.epa.gov/oppsrr d1/registration_review/ ). The Registration Review program is intended to ensure that, as the ability to assess risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard of no unreasonable adverse
effects to human health and the environment. Changes in science, public policy, and pesticide use practices will occur over time. Through the new Registration Review program, the Agency periodically reevaluates pesticides to make sure that as change occurs, products in the marketplace can be used safely.

As part of the implementation of the new Regist ration Review program purs uant to Section 3(g) of FIFRA, the Agency is beginning its evaluatio n of fenbutatin-oxide to determine whether it
continues to meet the FIFRA standard for re gistration. This problem formulation for the environmental fate, ecological risk, endangered species, and drinking water assessment chapter in support of the Registration Review is intende d for the initial docket opening public phase of the review process.

2.2. Previous Risk Assessments

Fenbutatin-oxide was first registered for use in 1974. The environmental risks associated with
fenbutatin-oxide were addresse d in a Reregistration Eligibil ity Decision (RED) signed in 1994 ( http://www.epa.gov/oppsrrd1/REDs/0245.pdf ). The RED identified the potential for chronic
risk to birds and mammals and acute and chronic risk to aquatic animals. As such, fenbutatin-

### 5 of 43 oxide was classified as a Restricted Use pesticide and toxicity warnings were added to the labels. However, no risks to non-target terrestrial insects, based on acute contact honey bee data, or acute risk to birds or mammals were expected from registered uses of the pesticide. Additionally, no risks to plants were anticipated from the registered fenbutatin-oxide uses; however, no plant data were available on which to base this conclusion. Following the RED, a Tolerance Reregistration Eligibility Decisi on (TRED) and associated Drinking Water Assessment were completed in 2002 ( http://www.epa.gov/oppsrrd1/REDs/fenbutatinoxide_tred.pdf ). The Agency did not identify any risk s of concerns from exposure to fenbutatinoxide in food or drinking water. Potential ecolo gical risks associated wi th fenbutatin-oxide were not assessed as part of the TRED action. Ot her environmental risk assessments for fenbutatinoxide which predate 1994 include assessments for six Section 3 new uses, one Experimental Use Permit, one Registration Standard, nine Secti on 18 emergency exemptions, and one New Product (Vendex ® 

### 4L in 1982, no longer active).

The most comprehensive recent assessment of eco logical risks associated with fenbutatin-oxide was completed in August 2007 as part of Secti on 3 new use assessment on pistachios (USEPA, 2007; DP 328390). Although the focus of the assessment was the new use of Vendex ® 

### 50WP on pistachios, risks associated w ith all registered fenbutatin-oxi de uses were assessed because previous assessments had not included the high est application rate for ornamentals nor had current methodologies (USEPA 2004) been used. Based on this analysis, it was determined that all currently registered uses of fenbutatin-oxide have th e potential for ad verse effects on freshwater fish, estuarine/marine fish, and estu arine/marine invertebrate s after both acute and chronic exposure; freshwater invertebrates after acute exposure; and birds and mammals following chronic exposure. Base d on the available honey bee data, a label statement to protect foraging honey bees was not required. However, b ecause fenbutatin-oxide is an acaricide, it was acknowledged that some terrestria l invertebrates (particularly spid ers and mites) might be more sensitive to fenbutatin-oxide than honey bees. In addition, based on the potential for phytotoxic effects to some plants as indicated on fenbutatin -oxide labels, plant inci dent reports, and an absence of plant toxicity data, ri sks to aquatic and terrestrial plan ts were assumed. A new dietary assessment was not conducted for this new use; instead, EPA relied on the estimates derived in
the TRED as conservative estimates for di etary exposure for the new use on pistachios.

Two previously registered fenbutat in-oxide end-use products, Orthonex ® 

### (Registration number 239-2594) and Ortho ® 

### Systemic Insect Killer (Registrat ion number 239-2595), were voluntarily cancelled by the registrant (73 FR 20642; USEPA 2008). The orders effecting these requested cancellations permit a registrant to sell or distribute existing stocks for 1 year after the date the cancellation request was received, or until April 2009. Therefore, these products will not be evaluated as part of the Regist ration Review for fenbutatin-oxide.

A complete listing of previous risk assessmen ts and their determinations is provided in Appendix C

.

### 6 of 43 3. Stressor Source and Distribution

3.1. Mechanism of Action

Fenbutatin-oxide is a non-systemic organotin acaricide that inhib its adenosine triphophate (ATP) synthase resulting in disruption of cellular respiration (i.e., oxi dative phosphorylation). This affects metabolic processes and ener gy production at the cellular level ( i.e ., the electron-transport chain ceases to operate). In addition, this trialkyl tin also inhibits photophosphorylation in chloroplasts, the chlorophyll-bearing subcellular units, and could therefore serve as an herbicide (Ma 2005).

3.2. Overview of Pesticide Usage

Fenbutatin-oxide is a restricted-use acaricide that was initially regi stered in the United States in 1974. The first end-use product was registered in 1975 for use on appl es, pears, and some citrus crops. Since that time, severa l other food crops and outdoor a nd greenhouse ornamental uses
have been added to the labels. There are tw o active Section 3 products containing fenbutatinoxide: ProMITE ® 

### 50WP (Registration nu mber 67690-40) and Vendex ® 

### 50WP Miticide (Registration number 70506-211). Both products can be applied via ground spray, aerial spray, or air blast application. ProMITE ® 

### 50WP is a dispersibl e granule while Vendex ® 

### 50WP is a wettable powder.

Fenbutatin-oxide comprises 50%, by weight, of both products which are distributed in watersoluble packets as restricted us e products. The maximum yearly application rate specified on the
label for non-residential uses is 8 lb a.i./acre (established landscape orna mentals). The maximum yearly application rate for out door ornamentals, however, is not specified on the label. Therefore, the yearly application rate for this us e could potentially be higher than 8 lb a.i./acre. An analysis of California Pesticide Use Rate (PUR) data for 1999 to 2007 for the two active products containing febutatin-oxi de indicates that the averag e maximum single use rate for outdoor ornamentals was 1.3 lbs a.i./acre, with a maximum annual application rate of 63 lbs a.i./acre (in 2005). Using these es timates, a retreatment interval (RTI) of approximately 8 days was estimated (365 days/year / (63 lb s a.i./acre/year / 1.3 lbs a.i./acre) = 8 days). In lieu of other data, the Agency will model 45 applications, using an 8 day RTI and a maximum single application rate of 2 lbs a.i. /acre for outdoor ornamentals.

A comprehensive list of currently registered fenbutat in-oxide uses, along with their respective methods, rates, and any geographic limitations are defined in

Table 1. Figure 1 below depicts the nationa l distribution of fenbutatin -oxide agricultural usage and indicates that use on citrus, almonds, appl es and peaches represented roughly 81% of the average annual use in 2002 (USGS 2009). The highest use areas were the California Central Valley, southern Florida, Washington State, and southernmost Texas.

### 7 of 43 Table 1. Methods and rates of application of currently registered uses of fenbutatin-oxide

Use Scenario Application Type Number of applications

per season Maximum Single Application Rate (lbs a.i./A) Maximum Annual Application Rate (lbs a.i./A) Apple Air or ground 2 1 2 Pear Air or ground 2 1 2 Grape Air or ground 2 1.25 2 Citrus (CA and AZ) Air or ground 2 2 3 Citrus (TX) Air or ground 2 1.5 3 Citrus (FL) Air or ground 2 1.5 2 Peach Air or ground 2 1 1.5 Plum Air or ground 2 1 1.5 Prune Air or ground 2 1 1.5 Nectarine Air or ground 2 1 1.5 Cherry (including sweet and sour) Air or ground 2 1.5 2.25 Papaya (except CA) Air or ground 4 1 4 Almond Air or ground 2 1.25 2 Pistachios Air or ground 2 1.25 2 Pecan Air or ground 2 1.25 2 Walnut Air or ground 2 1.25 2 Strawberry (CA only) Air or ground 3 1.5 4.5 Strawberry (except CA) Air or ground 2 1 2 Eggplant Air or ground 3 (per year) 1.5 4.5

Raspberry (WA and OR) Air or ground 1 (per year) 1 1

Outdoor ornamentals (including nursery stock, flowers, and plants grown for propagation) 1 Ground NS 3 2 2 NS 3

Established landscape ornamentals (commercial application to trees, shrubs, flowering ornamentals, bedding plants, annuals, and perennials) 1 Ground 4 (per year) 2 2 8

Christmas trees (WA and OR) Air or ground 1 1 1 NS – Not Specified

1 Occasional minor sensitivity has been observed on Salix melanostachys, Aspenium bulbiferum, Dryopteris erythosora, Cercis Ca nadensis, Camellia japonica, Pellaea rotundifo lia, Davallia fejeensis, Asparagus meyeri, Asplenium nidus, Adiantum cuneatum, Celosia argentea, Verbenea hortensis, Ageratum houstonianum, Rosa

sp.
2 Rate on label is 8 oz ai/100 gal. Maximum single application rate assumes 400 gal H 2 O/acre is applied.

3 In lieu of other data, the number of applications per y ear will be set to 45, with a RTI of 8 days, yielding a maximum annual application ra te of 90 lbs a.i./acre.

### 8 of 43 Figure 1. Fenbutatin-Oxide Usage Data for Agricultural Uses. (this map is from the following website accessed in June 2009: http://water.usgs.gov/nawqa/pnsp/usage/ maps/show_map.php?year=02&map=m6026 ).



### 3.3. Environmental Fate and Transport

Best-available data defining the phys ical, chemical, fate and trans port characteristics associated
with fenbutatin-oxide are summarized in Table 2

.

Table 2. General chemical and environmenta l fate properties of fenbutatin-oxide.

Chemical/Fate parameter Value Source (MRID) Study
Classification

Common Name Fenbutatin oxide NA NA

Chemical Name Bis [tris (2-methyl-2-phenylpropyl) tin] oxide NA NA

Pesticide Type Acaricide label NA

CAS Number 13356-08-6 NA NA

Empirical Formula C 60 H 80 O 1 Sn 2 NA NA

### 9 of 43 Chemical/Fate parameter Value Source (MRID) Study
Classification

Molecular Weight (g/mol) 1052.67 40365801 NA

Vapor Pressure (torr at 25°C) 1.8 x 10 -11 40365801 NA

Octanol-water Partition Coefficient (K OW ) 1.4 x 10 5 (log K OW =5.14) RED, 9/94 NA

Water Solubility (mg/L; at 20°C) 0.0127 RED, 9/94 NA

Hydrolysis half-lives (days) Stable , pH=5, 7, and 9 40790901 Acceptable

Aqueous Photolysis half-life (day s) 110, pH=7 40790902 Acceptable

Soil Photolysis half-life (days) 12 8 (sandy loam) 40696403 Acceptable

Aerobic Soil Metabolism half-life (days) 1,172 (loamy sand) 944 (silt clay loam) 2,951 (sandy clay loam) 40257001 Acceptable

Anaerobic Soil Metabolism half-life (days) 60 (loamy sand) 60 (silt clay loam) 60 (sandy clay loam) 40257002 Acceptable

Leaching/Mobility K d ; organic carbon partioning coefficient (K

oc ) (L/kg) 1,282; 320,677 (sandy loam) 2,333; 155,515 (loamy sand) 1,414; 74,450 (silt loam) 43336401 Acceptable

Bioaccumulation in fish, BC F 340-500x (muscle tissue) 1,100-1,600x (visceral tissue) 450-600x (remaining carcass) 490-730x (whole fish) 40696404 Not Acceptable

Terrestrial field dissipation half-life (soil texture) 1,367 days (silt loam soil – Delaware) 714 days (loam soil – Washington) 271 days (loam/sandy loam soil – California) 42896801 Acceptable

NA = not applicable



### Fenbutatin-oxide does not readily degr ade in the environment and is li kely to persist. There is no evidence of hydrolysis of fenbutatin-oxide. Th e compound does not appear to readily degrade by soil photolysis, or under aer obic and anaerobic conditions in soils. Fenbutatin-oxide is insoluble and is classified as hardly mobile to immobile (Kashuba, 2006). Major routes of dissipation include formation of bound residues in soils and sedime nt. During the anaerobic soil metabolism study (MRID 40257002) there appeared to be a decrease in fenbutatin-oxide
between initiation of anaerobic c onditions and the end of the st udy (60 days post initiation of anaerobic conditions). However, no pattern of degradation could be established and no degradation rate could be estima ted. In terrestrial field dissipa tion studies, concentrations of fenbutatin-oxide increased after multiple applicat ions due to the long half-life of the compound, indicating potential accumulation in the soil. Fenbutatin-oxide does appear to degrade by aqueous photolysis; only one major degrad ate was identified, i.e., 1,3-dihydroxy-1,1,3,3- tetrakis(2-methyl-2-phenyl propyl)-distannoxane (SD 31723). However, this is not expected to represent a major route of dissipation given th at aqueous photolysis w ould be limited to clear

### 10 of 43 shallow waters. Additionally, the degradat es SD 31723 and 2-methyl -2-phenylpropyl stannonic acid (SD 33608) were identified during the field dissipation studi es. Consistent with the laboratory data showing that the compound is relatively stable to bot h biotic and abiotic routes of degradation, terrestrial field dissipation studies indicate that the compound can persist with estimated half-lives of up to roughly 3.75 years. Depending on the soil type, use site, and meteorological conditions, fenbutatin-oxide may be transported off-site via runoff of sedimentbound residues (erosion) and spray drift. Given its low volatility (vapor pressure = 1.8 x 10 -11


### torr) and short half-life in ai r (0.4 hours, EPISuite v 4.0), tran sport via volatil ization and long range transport is not considered likely. In the submitted BCF study which has been classified as unacceptable, the accumulation of fenbutatin-oxide in the various tissue fractions did not reach a plateau (equilibrium) during the 28-day exposure period, so the actual BCF's may be significantly higher than those calculated. Additionally, as fenbutatin-oxide has a high logarithmic octanol-water partition coefficient (log K
ow 

### =5.14), bioconcentration and bioaccumulation in aquatic receptors and consum ption of aquatic food items by birds/mammals ( e.g . piscivorous birds/mammals) is a pathway of concern. Overall, febutatin-oxide has many properties associated with persistent, bioaccumulative, and toxic (PBT) compounds.

4. Receptors

Consistent with the process described in th e Overview Document (USEPA 2004), the risk
assessment for fenbutatin-oxide relies on a surro gate species approach. Toxicological data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, are used to extrapolate to poten tial effects on a variety of species (receptors)
included under these ta xonomic groupings.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the available open literature will be used to evalua te the potential direct and indirect effects of fenbutatin-oxide to aquatic and terrestrial recepto rs. This includes toxicity on the technical grade active ingredient, degradates, and when available, formulated products ( e.g. , “Six-Pack” studies). The open literature studies will be iden tified through EPA’s ECOTOXicology (ECOTOX) database (USEPA 2009a), which employs a litera ture search engine for locating chemical toxicity data for aquatic life, terrestrial plants , and wildlife. The eval uation of both sources of data may also provide insight into the direct and indirect effect s of fenbutatin-oxide on biotic communities from loss of species that are sensitive to the chemical and from changes in structure
and functional characteristics of the affected communities. The ECOTOX database was searched in February 2009. Based on the results of the ECOT OX query, no additional scientifically valid data were identified.

Table 3 provides a summary of the taxonomic groups and the surrogate species tested to characterize the potential acute a nd chronic ecological effects of fenbutatin- oxide. In addition, the table provides a preliminary overview of the potential acute toxicity of fenbutatin-oxide by providing the acute toxi city classifications.

A summary of the aquatic and te rrestrial toxicity data is provided in Sections 4.1 and 4.2, respectively. In addition, a summar y of ecological incidents associ ated with fenbutatin-oxide and a description of ecosystems potentia lly at risk are provided in S ections 4.3 and 4.4, respectively.

### 11 of 43 Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of Fenbutatin-oxide and the
Associated Acute Toxi city Classification.

Taxonomic Group Surrogate Species Acute and Chronic Toxicity Endpoints* Citation

MRID Acute Toxicity
Classification Bobwhite quail ( Colinus virginianus ) Acute oral LD 50 >2,510 mg a.i./kgbw 00113073 Practically non-toxic

Mallard duck ( Anas platyrhynchos ) and Bobwhite quail Sub-acute 8-day LC 50 >5,620 mg a.i./kg diet 00113074

40473505 Practically non-toxic

Birds 1

Mallard duck and Bobwhite quail Chronic avian reproduction study (19- to 21-weeks) NOAEC = 150 mg a.i./kg-diet; LOAEC = 500 mg a.i./kg-diet (based on reduction in number of eggs laid) 41258901

41258902 --

Acute oral LD 50 = 4,400 mg a.i./kgbw 40473504

Practically Non-toxic

Mammals Laboratory rat ( Rattus norvegicus ) Chronic 2-generation reproduction study; NOAEC = 75 mg a.i./kg-diet (5.13 mg a.i./kg-bw); LOAEC = 250 mg a.i./kg-diet (16.6 mg a.i./kg-bw) (based on reduced pup weight gain in

F 2 litters) 41540601

--

Acute contact 48-hr LD 50 = 3,982 μ g a.i./bee 00036935 Practically Non-toxic

Insects Honey bee ( Apis mellifera L. ) 24-hr toxicity of residues on foliage; no mortality at 1.75 lbs a.i./A 2 00088398

--

Acute 96-hr LC 50 =1.7 μg a.i./L (static; nominal concentrations) 00113075 Very highly toxic

Freshwater fish 3 Rainbow trout ( Oncorhyncus mykiss ) Chronic early life-stage (60-days) NOAEC = 0.31 μg a.i./L; LOAEC = 0.61 μg a.i./L (based on reducedlarval survival and growth) (flowthrough, measured concentrations) 40473512 --

Acute 48-hr EC 50 = 31 μg a.i./L (static; nominal concentrations) 40473509 Very highly toxic

Freshwater
invertebrates Water flea ( Daphnia magna ) Chronic (21-day) NOAEC = 16 μg a.i./L; LOAEC = 39 μg a.i./L (based on reduced growth and percent
survival in adults and total number of young) (static renewal; measured concentrations) 40525901 --

Estuarine/marine
fish Sheepshead minnow ( Cyprinodon variegatus ) Acute 96-hr LC 50 = 20.8 μg a.i./L (flow-through; measured concentrations) 41483301 Very highly toxic

### 12 of 43 Taxonomic Group Surrogate Species Acute and Chronic Toxicity Endpoints* Citation

MRID Acute Toxicity
Classification

NA Chronic Study = NA ACR-derived NOAEC = 3.80 μg
a.i./L NA NA

Mysid ( Americamysis
bahia ) Acute 96-hr LC 50 = 2.8 μg a.i./L (static; measured concentrations) 40590508 Very highly toxic

Eastern oyster ( Crassostrea virginica ) Acute 48-hr EC 50 = 0.37 μg a.i./L (static; measured concentrations) 40590507 Very highly toxic Estuarine/marine
invertebrates

NA Chronic Study = NA ACR-derived NOAEC = 0.19 μg
a.i./L NA NA

Terrestrial plants NA NA NA NA

Aquatic plants and algae NA NA NA NA

* Test conditions are presented for aquatic animal studies.

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles.

2 Tested with Vendex 50 WP.

3 Freshwater fish may be surrogates for aquatic-phase amphibians.
NA = Data not available



### 4.1. Effects to Aquatic Organisms

Fenbutatin-oxide is classified as very highly toxic to freshwater and estuarine/marine fish and invertebrates on an acute exposure basis. Based on the available acute to xicity data, it appears
that estuarine/marine invertebrates are more sensitive to fenbutatin-oxide than freshwater invertebrates, whereas freshwater fish appear to be more acutely sensitive than estuarine/marine
fish. It should be noted that the acute toxi city endpoints for freshwater invertebrates and
estuarine/marine fish exceed the solubility limit of fenbutatin-oxi de (12.7 μg a.i./L); however, a solvent (i.e., acetone) was used to enhance th e solubility in these acute studies.

In addition, there is a high degree of uncertainty associated with the acute freshwater fish and
invertebrate data because the tests were conduc ted under static conditions and only nominal test
concentrations were available. It should be not ed that study classificati ons for two of the acute freshwater fish studies (MRIDs 113075 and 113076) and the freshwater invertebrate study (MRID 40473509) have been downgraded from ‘acceptable’ to ‘supplemental’ because endpoints from these studies, which were based on nomimal concentrations, likely underestimate the toxicity of fenbutatin-oxide due to its low solubility and propensity to bind to the glass
surfaces of test containers. Given the low solubi lity and tendency for fenbutatin-oxide to sorb,
measured test concentrations are required in freshwater acute studi es to provide reliable exposure concentrations and measurement endpoints.

### 13 of 43 Chronic exposure to fenbutatin-oxide resulted in a reduction in larval su rvival and growth in freshwater fish and a reduction in growth and percent of adult survival, and decreased reproduction (reduced total number of young) in freshwa ter invertebrates. Chronic toxicity data
are not available for estuarine/marine fish and in vertebrates; therefore, an acute-to-chronic ratio is used to estimate chronic endpoi nts based on freshwater fish a nd invertebrate data. Based on the freshwater fish data for rainbow trout, th e resulting estimated NOAEC for estuarine/marine fish is 3.80 μg a.i./L (freshwater fish LC 50 

### of 1.7 μg a.i./L / freshwater fish NOAEC of 0.31 μg a.i./L = 5.48; estuar ine/marine fish LC 50 

### of 20.8 μg a.i./L / 5.48 = 3.80 μg a.i./L). Based on the
freshwater invertebrate data for daphnid, the estimated NOAEC for estuarine/marine invertebrates is 0.19 μg a.i./L (freshwater invertebrate EC 50 

### of 31 μg a.i./L / freshwater invertebrate NOAEC of 16 μg a.i./L = 1.94; estuarine/marine invertebrate EC 50 

### = 0.37 μg a.i./L / 1.94 = 0.19 μg a.i./L. However, given that fenb utatin-oxide is less toxic to freshwater
invertebrates than estuarine/marine invertebrate s, there is uncertainty associated with using
freshwater invertebrate data as surrogate to estimate chronic toxicity for estuarine/marine invertebrates. In addition, given the propensity of fenbutatin-oxide to sorb to sediment, there is uncertainty associated with the potential for toxic ity to freshwater and es tuarine/marine benthic
invertebrates.

No registrant-submitted toxicity data are available for aquatic plants, nor were any scientifically valid data identified in the open literature.

4.2. Effects to Terrestrial Organisms

Fenbutatin-oxide is classified as practically non-toxic to bird s, mammals, and honey bees on an acute exposure basis. For birds, chronic e xposure resulted in decr eased reproduction (reduction in the number of eggs laid); for mammals, ch ronic exposure resulted in decreased growth (reduction in body weight, food consumption, and pup weight during lactati on). No fenbutatinoxide data are available for terres trial plants. Terrestrial plant t oxicity data are also unavailable for other organotin compounds, such as cyhexatin and tributyltin (TBT).

4.3. Effects of Degradates

Based on the results of previous fenbutatin-oxi de assessments, no degradates of concern have
been identified. The Health Effects Divi sion’s (HED) Metabolism Assessment Review Committee (MARC) met on March 20, 2001 to consid er the degradation of fenbutatin-oxide in water. Specifically, MARC was asked to determin e which degradates should be included in the
risk assessment. The Committee concluded that the parent compound, fenbutatin-oxide, was the only residue to be included in a drinking wa ter risk assessment. Although MARC expressed concern about the toxicity of other metabol ites of fenbutatin-oxide, the Committee did not recommend including them in a drinking water risk assessment because they were only likely to be present in drinking water at ve ry low levels, if at all. Th e Committee based its decision on the following: (1) in laboratory and fi eld studies, the degradates were found only at trace levels or not at all; and (2) based on the fate and transpor t of fenbutatin oxide in the environment, only the parent was expected to reach the surface water, where degradation may occur via aqueous photolysis, but only in very small quantities. As a result, no degradates of concern were
identified.

### 14 of 43 4.4. Incident Database Review

The Agency maintains an incident database syst em (Ecological Incident Information System or EIIS) to track and evaluate accidental kills associ ated with pesticide use. The likelihood that a particular pesticide caused the inci dent is classified as “highly probable”, “probable”, “possible”, or “unlikely”, based on the information contained in the incident report. In the years since EPA has maintained the database, a to tal of two incidents associated with fenbutatin-oxide use have been reported (both involving terr estrial plants), based on a search of EIIS in July 2009 (USEPA, 2009b). Of these incidents, one was reported in California involving oranges (incident no.: I013636-036) and one was reported in Washingt on, DC, involving a dwarf Alberta pine tree (incident no.: I009262-105). The cer tainty in which these incident s were a result of fenbutatinoxide use was described as “possible” in the CA incident and “probable” in the DC incident. One of the incidents was the result of registered use (involving oranges), while it is unknown if
the incident resulted from misuse or registered use in the other incident (involving the pine tree). Fenbutatin-oxide was not the only active ingredient involved in either incident. Specific details
of the incidents are described below.

Incident I013636-036 (Oranges in Tulare County, California)

After ground application of a tank mixt ure including chlorpryrifos (Lorsban ® 

### 4E), spinosad (Success ® 

### ), and fenbuatain-oxide (Vendex ® 

### ) (at registered applica tion rates) in March 2002, a farmer claimed spotting on oranges in 21 out of 40 acres of his orchard. The ‘certainty index’ for all three active ingredients associated with the incident was listed as ‘possible’. No chemical residue analyses were conducted. Both chlorpyrifos and spinosad are insecticides. Available terrestrial plant data for spinosad indicates that it is not toxic to plants. In contrast, phytotoxic effects associated with chlorpyrifos have been demonstrated in the fiel d; however, no terrestrial plant toxicity data are available for this chemical.

Incident I009262-105 (Dwarf Albe rta Pine in Washington, DC)

ScottsTM Company received a complaint from a person in August 1999 whose dwarf Alberta pine tree died after it was sprayed with Isotox ® 

### Insect Killer (later renamed Ortho ® 

### Systemic Insect Killer). This end-use product contained two activ e ingredients: acephate and fenbutatin-oxide. The ‘certainty index’ for both actives was listed as ‘probable’. No chemical residue analyses were conducted and the legality of use was reported as unknown. It is important to note that the
Ortho ® 

### Systemic Insect Killer end-use product wa s voluntarily cancelled in April 2008 (see FR 20642; April 16, 2008).

4.5. Ecosystems Potentially at Risk

The ecosystems at risk are often extensive in scop e; therefore, it may not be possible to identify specific ecosystems during the development of a nation-wide ecological risk assessment. However, in general terms, terrestrial ecosystem s potentially at risk could include the treated field and areas immediately adjacen t to the treated field that may receive drift or runoff. Areas

### 15 of 43 adjacent to the treated field could include cultiv ated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, woodlands, ripari an habitats and other uncultivated areas.

Aquatic ecosystems potentially at risk include wa ter bodies adjacent to, or down stream from, the treated field and might include impounded bodies such as ponds, lake s and reservoirs, or flowing waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also includes marine ecosystems, including estuaries.

5. Assessment Endpoints

Assessment endpoints represent the ac tual environmental value that is to be protected, as defined by an ecological entity (species, community, or ot her entity) and its attribute or characteristics (USEPA 1998). For fenbutatin-oxide, the ecologi cal entities include the following: birds, reptiles, terrestrial-phase amphibians, mammal s, freshwater fish, fres hwater aquatic-phase amphibians and invertebrates, estuarine/marine fish and invertebrates, terrestrial plants, terrestrial invertebrates, and aquatic plants. Th e attributes for each of these entities include growth, reproduction, and survival.

6. Conceptual Model

For a pesticide to pose an ecological risk, it mu st reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide moves in the environment from a source to an ecological recepto r. For an ecological pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, an d a feasible route of exposure.

The conceptual model for fenbutatin-oxide pr ovides a written desc ription and visual representation of the predicted relationships between fenbutatin -oxide, potential routes of exposure, and the predicted effects for the assess ment endpoint. A conceptual model consists of two major components: risk hypothesis a nd a conceptual diagram (USEPA 1998).

6.1. Risk Hypothesis

A risk hypothesis describes the predicted re lationship among the stre ssor, exposure, and assessment endpoint response along with the rationa le for their selection. For fenbutatin-oxide, the following ecological risk hypothe sis is being employed for this national-level ecological risk

assessment:

Based on the application methods, mode of ac tion, direct toxicity to non-target aquatic and terrestrial species, and pot ential indirect effects to trophic food webs, the use of fenbutatin-oxide has the potential to redu ce survival, reproducti on, and/or growth in terrestrial and aquatic animals and plants thro ugh direct applicati on, spray drift, and runoff of sediment-bound re sidues (erosion). These non-target organisms include Federally-listed threatened and endangered sp ecies as well as non-listed species.

### 16 of 43 In order for a chemical to pose an ecologica l risk, it must reach non-target organisms at
concentrations found to cause a dverse effects. The assessment of ecological exposure pathways will include an examination of the source and po tential migration pathways to fenbutatin-oxide exposure, and the determination of potential adverse effects on non-target species.

6.2. Conceptual Diagram

Application methods for fenbuta tin-oxide involve foliar spray applications via ground, aerial, and hand-held equipment. For orchards, the most-likely application method is via ground application (orchard airblast); however, since aerial a pplications are not pr ecluded on the labels, both ground and aerial applications will be assesse d. Ecological receptors that may potentially be exposed to fenbutatin-oxide include terrestrial and semi-aquatic wildlife ( i.e. , mammals, birds, terrestrial-phase amphibians, terrestrial inverteb rates, and reptiles) a nd plants. In addition, aquatic receptors ( e.g ., freshwater and estuarine/marine fi sh and invertebrates, aquatic-phase amphibians, and plants) may also be exposed as a result of potential m ovement of fenbutatinoxide via spray drift and/or runo ff of sediment-bound residues from the site of application to aquatic environments. Fenbutatin-oxide also has a potential for adsorption to sediment and for bioaccumulation in the lipids of aquatic organisms; therefore, exposure of benthic organisms to fenbutatin-oxide from sediment (pore water) and to piscivorous mammals and birds via consumption of aquatic invertebrates and fish is possible. The transport mechanisms (e.g., sources) are depicted in the conceptual models below ( Figures 2 and 3 ) and result in the
movement of fenbutatin-oxide into aquatic (water and sediment) a nd terrestrial (soil and foliage) habitats. The movement away from the site of application in turn repr esents exposure pathways for a broad range of biological receptors of c oncern (non-target animal s and plants) and the potential attribute changes, i.e. , effects such as reduced surviv al, growth and reproduction, in the receptors due to fenbutatin-oxide exposure.

The assessment will not account for ingestion of fenbutatin-oxide residues by animals in drinking water or contaminated grit, ingesti on through preening activit ies, or uptake through inhalation or dermal absorption by terrestrial anim als. Exposure to terrestrial animals is based primarily on dietary consumption of foliar resi dues while aquatic assessments assume that all major potential routes of direct exposure are accounted. Given th e low solubility of fenbutatinoxide and its propensity to partiti on to sediments, the chemical is not expected to leach in groundwater. Also, given the lo w volatility of fenbutatin-oxi de coupled with its short atmospheric half-life, the compound is not expected to move via atmospheric transport. As such, neither groundwater nor atmos pheric deposition is expected to contribute appreciably to

exposure.

### 17 of 43 ** Route of exposure includes only ingestion of aquatic fish and invertebrates 

### Stressor

Source

Receptors

Attribute Change Ground, aerial, or air blast application of fenbutatin-oxide to agricultural, orchard, and ornamental uses

Spray drift

Fish/aquatic-phase amphibians
**Piscivorous mammals

and birds

Individual organisms

Reduced survival Reduced growth Reduced reproduction Food chain Reduction in algae Reduction in prey
Modification of PCEs

related to prey availability Habitat integrity Reduction in primary productivity
Reduced cover Community change
Modification of PCEs related to

habitat Surface water/
Sediment Runoff

Aquatic Animals

Invertebrates
Vertebrates 

### Exposure
Media

Uptake/gills or integument

Ingestion Ingestion Soil

Uptake/gills or integument

Aquatic Plants

Non-vascular
Vascular Uptake/cell, roots, leaves Riparian plants

terrestrial

exposure pathways see Figure 3

Figure 2. Conceptual model for potential fenbutatin-oxide ef fects on aquatic organisms. Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk.

### 18 of 43 

### Stressor

Source

Attribute Change Ground, aerial, or air blast application of fenbutatin-oxide to agricultural, orchard, and ornamental uses

Direct application Spray drift

Birds/terrestrialphase amphibians/ reptiles/mammals

Terrestrial

insects

Individual organisms

Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey
Modification of PCEs

related to prey availability Habitat integrity Reduction in primary productivity
Reduced cover Community change
Modification of PCEs related

to habitat Terrestrial plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Birds/ Reptiles/

Mammals 

### Exposure Media & Receptors Soil

Ingestion Ingestion

Ingestion Ingestion Dermal uptake/Ingestion

Root uptake

Terrestrialphase amphibians Ingestion

Figure 3. Conceptual model for potential fenbut atin-oxide effects on terrestrial organisms.



### 7. Analysis Plan

In order to address the risk hypot hesis, the potential for adverse effects on the environment is estimated. The use, environmental fate, and ecological effects of fenbutatin-oxide are characterized and integrated to assess the risks. This is accomplished using a risk quotient (ratio of exposure concentration to eff ects concentration) approach. A lthough risk is often defined as the likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does not provide a quantitative estima te of likelihood and/or magnitude of an adverse effect. However, as outlined in the Overview Docume nt (USEPA 2004), the likelihood of effects to individual organisms from partic ular uses of fenbutat in-oxide is estimated using the probit doseresponse slope and either the level of concern (d iscussed below) or the actual calculated risk quotient value.

This analysis plan will be re visited and may be revised dependi ng upon the data available in the open literature and the information submitted by the public in response to the opening of the Registration Review docke t for fenbutatin-oxide.

### 19 of 43 7.1. Stressors of Concern

Two environmental degradates, 1,3-dihydroxy- 1,1,3,3-tetrakis(2-methyl-2-phenyl propyl)- distannoxane (SD 31723) and 2-methyl-2-phenylp ropyl stannonic acid (SD 33608), have been identified in the field dissipation studies. On a structural basis, these de gradates are not similar to the parent ( Appendix A ) and based on the results of previ ous risk assessments for fenbutatinoxide, these degradates are not of toxicological concern (see Section 4.3 ). Therefore, the focus of this assessment is expected to be the parent , fenbutatin-oxide, particularly given that it does significantly not degrade.

Evaluation of environmental pesticide mixtures is beyond the scope of this assessment because of the myriad factors that cannot be quantified ba sed on the available data. Those factors include identification of other possible co-contaminants and their concentrations, differences in the pattern and duration of exposure among contamin ants, and the differential effects of other physical/chemical characteristic s of the receiving waters ( e.g. organic matter present in sediment and suspended water). Evaluation of factors th at could influence additivity/synergism is beyond the scope of this assessment and the capabilities of the available data to allow for an evaluation. However, it is acknowledged that not considering mixtures c ould over- or under-estimate risks depending on the type of interacti on and factors discussed above.

7.2. Measures of Exposure

In order to estimate risks of fenbutatin-oxide ex posures in aquatic and te rrestrial environments, all exposure modeling and resulting risk conclu sions will be based on maximum application rates
and methods cited in

Table 1 and will be estimated for each use of fe nbutatin-oxide. Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of
fenbutatin-oxide. The models us ed to predict aquatic EECs are the Pesticide Root Zone Model coupled with the Exposure Analysis Model Sy stem (PRZM/EXAMS). The model used to predict terrestrial EECs on food items is T-REX. The model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant. Th ese models are parameterized using relevant reviewed environmental fate data from registra nt submissions and the literature; model input
values will be consistent with the most recent version of the input para meter guidance (Version 2; EFED 2002).

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are simulation models coupled with the input shell pe5.pl (Aug 2007). The mode ls generate daily exposures and calculated 1- in-10 year EECs of fenbutatin-oxide that ma y occur in surface water bodies adjacent to application sites receiv ing fenbutatin-oxide through runoff an d spray drift. PRZM simulates pesticide application, movement, and transforma tion on an agricultural field and the resultant pesticide loadings to a recei ving water body via runoff, erosion and spray drift. EXAMS simulates the fate of the pesticide in the water body and estimates resulting concentrations. The

### 20 of 43 standard scenarios used for ecological pesticide assessments assume application to a 10-hectare agricultural field that drains into an adjacent 1-hectare water body that is 2 meters deep (20,000

m 3 

### volume) with no outlet. PRZM/EXAMS is us ed to estimate screen ing-level exposure of aquatic organisms to fenbutatin-oxide. The meas ure of exposure for aquati c species is the 1-in10 year return peak or rolling mean concentration. The 1-in-10 year peak is used for estimating acute exposures of direct effects to aquatic organisms. The 1-in-10-year 60-day mean is used for assessing chronic exposure to fish and aquatic-ph ase amphibians. The 1-in-10-year 21-day mean is used for assessing chronic expos ure to aquatic invertebrates.

In addition to modeling estimates, available monitoring data will be evaluated. Monitoring data will include those collected/reported by states as well as other federal departments/agencies (e.g., USGS National Water Quality Assessment (NAQWA; http://water.usgs.gov/nawqa/)).

Exposure estimates for terrestrial an imals assumed to be in the target area or in an area exposed to spray drift are derived using the T-REX model (version 1.4.1, 10/08/2008). This model incorporates the Kenega nomogr aph, as modified by Fletcher et al . (1994), which is based on a large set of field residue data . The upper limit values from the nomograph represent the 95 th


### percentile of residue values from actual field measurements (Hoerger and Kenega 1972). The
Fletcher et al . (1994) modifications to the Kenega nomograph are based on measured field residues from 249 published research papers, incl uding information on 118 species of plants, 121 pesticides, and 17 chemical classes. EECs for te rrestrial plants inhabiti ng dry and wetland areas are derived using TerrPlant (ver sion 1.2.2, 12/26/2006). This model us es estimates of pesticides in runoff and in spray drift to calculate EECs. EECs are based upon solub ility, application rate and minimum incorporation depth.

The KABAM model ( K OW 

### (based) A quatic B io A ccumulation M odel; version 1.0; 4/7/09) is used to estimate potential bioaccumulation of fe nbutatin-oxide residues in freshwater aquatic food webs and subsequent risks to mammals and birds via consumption of contaminated aquatic prey. KABAM is composed of two parts: 1) a bioaccumulation model that estimates pesticide concentrations in aquatic organisms; and 2) a risk component that translates exposure and toxicological effects of a pesticide into ri sk estimates for mammals and birds consuming contaminated aquatic prey. This model is based upon work by Arnot and Gobas (2004), who parameterized it based on polychlorinated biphenyls (PCBs) and a number of hydrophobic organic pesticides ( e.g. , lindane, DDT) in the Great Lakes. The model relies upon a chemical’s

K OW 

### to estimate uptake and elimination constants through respiration and diet of organisms in different trophic levels of the aquatic communit y. Fenbutatin-oxide residue concentrations are
calculated at the basic levels of a food web ( e.g. , phytoplankton). Accumulation in higher trophic level organisms is modeled through diet and respiration. The model used in this assessment incorporates seven trophic leve ls, including: phytoplankton, zooplankton, benthic invertebrates, filter feed ers, small juvenile fish, medium sized fish, and larger upper-trophic level
fish.

Two spray drift models, AGDisp and AgDRIFT are us ed to assess exposures of terrestrial plants to fenbutatin-oxide deposited in terrestrial habitats by spray drif t. AGDisp (version 8.13; dated 12/14/2004) is used to simulate aerial and gr ound applications. AgDr ift (version 2.01; dated 5/24/2001) is used to simulate spray blast applications to orchard crops.

### 21 of 43 7.3. Measures of Effect

Ecological effects data are used as measures of di rect and indirect effects to biological receptors. Data are obtained from registrant-submitted studies or from literature studies identified by
ECOTOX. The ECOTOX database (USEPA 2009a) was searched in order to provide more ecological effects data to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data and potential chemical mi xture toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX wa s created and is maintained by the USEPA, Office of Research and Development, and the National Health and Environmental Effects Research Laboratory's Mid-Continent Ecology Division.

Information on the potential effects of fenbutatin- oxide on non-target anim als is also collected from the Ecological Incident Information System (EIIS; USEPA 2009b). The EIIS is a database containing adverse effect (typic ally mortality) reports on non -target organisms where such
effects have been associated with the use of pesticides. Inci dents reported in the aggregate incident reports and the Avian Incident Monitori ng System (AIMS) will also be searched. AIMS is a database administered by the American Bi rd Conservancy (it was partially funded by the EPA). It contains publicly available data on reported avian incidents involving pesticides (http://www.abcbirds.org/abcprograms/po licy/pesticides/aims/aims/index.cfm).

Where available, sublethal effects observed in both registrant-submitted and open literature studies will be evaluated qualitatively. Such effects may include behavioral changes ( e.g. , lethargy and changes in colora tion). Quantitative assessments of risks, though, are limited to those endpoints that can be di rectly linked to the Agency’s assessment endpoints of impaired survival, growth and reproduction.

The assessment of risk for direct effects to non-target organisms makes the assumption that toxicity of fenbutatin oxide to bi rds is similar to terrestrial-pha se amphibians and reptiles. The same assumption is made for fish and aquatic-phase amphibians.

The acute measures of effect used fo r animals in this assessment are the LD 50 

### , LC 50 

### and EC 50



### . LD stands for "Lethal Dose", and LD 50 

### is the amount of a material, given all at once, that is
estimated to cause the death of 50% of the test organisms. LC st ands for “Lethal Concentration”
and LC 50 

### is the concentration of a chemical that is estimated to kill 50% of the test organisms.
EC stands for “Effective Concentration” and the EC 50 

### is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non-lis ted animals are the NOAEL/NOAEC and NOEC.
NOAEL stands for “No Observed-Adverse-Effect-Level ” and refers to the hi ghest tested dose of a substance that has been reported to have no harm ful (adverse) effects on test organisms. The NOAEC ( i.e. , “No-Observed-Adverse-Effect-Concentration” ) is the highest test concentration at
which none of the observed effects were statistically different fr om the control. The NOEC is
the No-Observed-Effects-Concentration. Fo r non-listed plants, only acute exposures are assessed ( i.e. , EC 25 

### for terrestrial plants and EC 50 

### for aquatic plants); for listed plants, either the

NOAEC or EC 05 

### is used.

### 22 of 43 7.4. Integration of Exposure and Effects

Risk characterization is the integration of e xposure and ecological effects characterization to determine the potential ecological risk from the use of fenbutatin-oxide on agriculture, orchards,
and ornamentals and the likelihood of direct and indirect effect s to non-target organisms in aquatic and terrestrial habitats. The exposure and toxicity effects da ta are integrated in order to
evaluate the risks of adverse ecological effects on non-target species. For the assessment of fenbutatin-oxide risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divide d by acute and chronic toxicity values. The resulting RQs are then compared to the Agency’s Levels of C oncern (LOCs) (USEPA 2004). These criteria are used to indicate when fenbutatin-oxide’s uses, as directed on the label, have the potential to
cause adverse direct or indirect effects to non-target organisms.

7.5. Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point-estimate based (RQ) approach described in the risk assessment. Depending on the risk manager's need for additional information regarding risk, an effort will be made to further qualitatively describe risk using probabilistic tools that the Agency has developed. These tools have been reviewed by FIFRA Scientific Advisory Panels ( http://www.epa.gov/sc ipoly/sap/index.htm ) and have been deemed as appropriate means of refining asse ssments where deterministic approaches have
identified risks.

7.6. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to Federally-listed th reatened and/or endangere d (listed) species from registered uses of fenbutatin-oxide. This asse ssment will be conducted in accordance with the Overview Document (USEPA 2004), provisi ons of the ESA, and the Services’ Endangered Species Consultation Handbook (USFWS/NMFS, 1998).

The assessment of effects associated with the registration of fenbutatin -oxide is based on an
action area. The action area is considered to be the area directly or indi rectly affected by the federal action, as indicated by the exceedance of Agency Levels of Concern (LOCs) used to
evaluate direct or indi rect effects. The Agency’s appro ach to defining the action area under the provisions of the Overview Document (USEPA 2004) considers the results of the risk assessment process to establish boundaries for that action area with the understanding that exposures below the Agency’s defined LOCs constitute a no-effect threshold. For the purposes of this assessment, attention will be focused on the footprint of the action ( i.e ., the area where fenbutatin-oxide application occurs) that exceed s the Agency’s LOCs. Specific measures of ecological effect that define th e action area for listed species in clude any direct and indirect effects and/or potential modification of its critical habita t, including reduction in survival, growth, and reproduction as well as the full suite of sublethal effects av ailable in the effects literature. Therefore, the ac tion area extends to a point wher e environmental exposures are below any measured lethal or sublethal effect threshold for any biologica l entity at the whole organism, organ, tissue, and cellula r level of organization. In situ ations where it is not possible

### 23 of 43 to determine the threshold for an observed effect, the action area is not spatially limited and is
assumed to be the entire United States.

7.7. Drinking Water Assessment

The most recent drinking water assessment wa s conducted in 2001 in support of the fenbutatinoxide TRED. However, the estimates were de rived using older versions of the PRZM/EXAMS models. As such, a drinking water assessment will be conducted to support future human health
risk assessments of fenbutatin-oxide. The dri nking water assessment will incorporate model estimates of fenbutatin-oxide in surface and grou nd waters. Concentrati ons of fenbutatin-oxide in surface waters will be estimated using PRZM/EXAMS (see description above). Ground water
estimates of fenbutatin-oxide c oncentrations will be establis hed using SCI-GROW (v.2.3, July 2003). The drinking water assessment will also include available surface and ground water monitoring data, with consideration of changes in use patterns since mitigations have been imposed. States are encouraged to submit monitoring data for review.

7.8. Preliminary Identification of Data Gaps

Fenbutatin-oxide use is defined as having te rrestrial, food and non-food uses and greenhouse uses. According to Code of Federal Regula tions 40 (CFR40 2007) Part 158 Subpart D (data requirements for pesticides) environmental fate a nd non-target organism effe ct data are required
for fenbutatin-oxide based on its terrestrial use. Available studies submitted to fulfill environmental fate and ecological effects guidel ine requirements, as well as outstanding data gaps for fenbutatin-oxide, are defined in Table 4-7, below.

Further information on data required to fulf ill the Agency’s guideline requirements for
fenbutatin-oxide and its formulat ed products is presented as th e Data Call-in (DCI) table in Appendix B . In addition to providing the guideline num ber and study title for required data, the DCI table provides a rationale for requiring the data , an explanation of how the data will be used, and a brief description of the how the data coul d impact the Agency’s future decision-making.

7.8.1. Fate

The environmental fate data requirements for fenbut atin-oxide are partially fulfilled with some data gaps still remaining ( Table 4 ). Data gaps include the aerobic and anaerobic aquatic
metabolism data and the bioaccumulation data. Th e data gap for the bioaccumulation data is
discussed below.

Table 4. Available environmenta l fate data for fenbutatin-oxide and remaining data gaps.

Guideline Description MRID Classification Data Gap? Comments

835.2120 Hydrolysis 407909-01 Acceptable No

835.2240 Photodegradation in water 407909-02 Acceptable No

835.4100 Aerobic soil metabolism 402570-01 Acceptable No

835.4200 Anaerobic soil metabolism 402570-02 Acceptable No

835.4300 Aerobic Aquatic Metabolism NA Yes

835.4400 Anaerobic Aquatic Metabolism NA Yes None

### 24 of 43 Guideline Description MRID Classification Data Gap? Comments

835.1230

835.1240 Leaching and adsorption/ desorption 402570-03

402570-04

433364-01 Acceptable No

835.6100 Terrestrial Fi eld Dissipation 420745-01

416085-01

428968-01 Acceptable No

850.1730 Bioaccumulation in Fish 406964-04 Not acceptable Yes

NA = not available



### Bioaccumulation in Fish Study

In the submitted study (MRID 406964-04), fenbutatin oxide residues accum ulated in bluegill sunfish ( Lepomis macrochirus ); however, the accumulation of fenbutatin-oxide in the various tissue fractions did not reach a plateau (e quilibrium) during the 28-day exposure period. Therefore, the actual BCFs may be significantly higher than those calculated. As such, to accurately define the bioaccumulation potential of fenbutatin-oxide, a new fish BCF study is needed. The new data could substantially a lter our understanding of potential exposure through the aquatic food chain.

7.8.3. Effects

Although many submissions have been made to provi de data on the effects of fenbutatin-oxide to aquatic and terrestrial organisms, several data gaps still exist ( Table 5-7 ). The data gaps, which are discussed in further detail below, include th e following: avian acute oral toxicity testing, chronic toxicity studies with estu arine/marine fish and invertebra tes, sediment toxicity studies
with freshwater and estuarine/marine invertebra tes, and Tier I aquati c and terrestrial plant studies. In addition, acute toxic ity studies with measured test concentrations are required for
freshwater fish and invertebrates.

Table 5. Available ecological effects data for terres trial animals exposed to fenbutatin-oxide and its formulated products and remaining data gaps.

Guideline Description MRID Classification Data Gap? Comments

850.2100 Avian oral toxicity 113073 Acceptable Yes*

850.2200 Avian dietary toxicity 113074 Acceptable No

41258901 Acceptable No 850.2300 Avian reproduction

41258902 Acceptable No

850.3020 Honey bee acute contact toxicity 36935 Acceptable No *Avian acute oral toxicity data are not available for a passerine species, which are required under the new 40 CFR Part 158. An acute oral toxicity study using passerines must be submitted to fulfill this data requirement.

### 25 of 43 Table 6. Available ecological effects data for aquatic animals exposed to fenbutatin-oxide and remaining data

gaps.

Guideline Description MRID Classification Data Gap? Comments

113075 Supplemental

40098001 Supplemental 850.1075 Freshwater fish – Acute toxicity

113076 Supplemental Yes 1

850.1075 Saltwater fish – Acute toxicity 41483301 Acceptable No

850.1010 Freshwater
invertebrates – Acute toxicity 40473509 Supplemental Yes 2

40590507 Supplemental 850.1025

850.1035

850.1045

850.1055 Saltwater invertebrates –Acute toxicity

40590508 Supplemental No

850.1300 Freshwater
invertebrate – life cycle test 40525901 Acceptable No

850.1350 Mysid chronic toxicity

test None NA Yes 3

850.1400 Freshwater fish – early life stage test 40473512 Supplemental No

850.1400 Saltwater fish – early life stage test None NA Yes 4

850.1735 Whole sediment toxicity invertebrates,
freshwater None NA Yes 5

850.1740 Whole sediment toxicity invertebrates,
marine None NA Yes 6 1 A flow-through freshwater fish acute study (850.1075) with measured test concentrations is required for
fenbutatin-oxide in order to reduce uncertainties associated with potential underestimation of toxicity due to the chemical’s low solubility and propensity to sorb.

2 A flow-through freshwater invertebrate acute study (850.1010)
with measured test concentrations is required for fenbutatin-oxide in order
to reduce uncertainties associated with

potential underestimation of toxicity due to the chemical’s low solubility and propensity to sorb.

3 A chronic mysid toxicity test (850.1350 is is required for fenbutatin-oxide because the acute toxicity value for saltwater fish is < 1 mg/L.

4 A saltwater fish early-life stage test (850.1400) is required for fenbutatin-oxide because the acute toxicity value for saltwater fish is < 1 mg/L.

5 A whole sediment chronic study with freshwater invertebrates (850.1735) is required based on the partitioning tosediment and the persistence of fenbutatinoxide.

6 A whole sediment chronic study with marine invertebrates (850.1740) is required based on the partitioning and persistence of
fenbutatin-oxide and the increased sensitivity of estuarine/marine invertebrates
relative to freshwater invertebrates.

NA = not available

### 26 of 43 Table 7. Available ecological effect s data for plants exposed to fenbut atin-oxide and remaining data gaps.

Guideline Description MRID Classification Data Gap? Comments

850.4100 Terrestrial Plant toxicity: Tier I seedling emergence None NA Yes*

850.4150 Terrestrial Plant toxicity: Tier I vegetative vigor None NA Yes*

850.5400 Aquatic Plant Growth: algae None NA Yes*

850.4400 Aquatic Plant Growth: vascular plants None NA Yes* *Tier I terrestrial and aquatic plant toxicity tests ar e required for all
terrestrial food and non-food use
patterns.

NA = not available



### Avian Acute Oral Toxicity

Acceptable acute avian oral toxicity da ta were submitted for the bobwhite quail ( Colinus virginianus ); however, data are not available for a passerine species, which are now required under the 40 CFR Part 158 (CFR 40 2007) data requi rements for conventional pesticides (72 FR 60934; USEPA 2007). The Part 158 data requirements specify that acute avia n oral toxicity data be submitted for either a mallard duck ( Anas platyrhynchos ) or bobwhite quail AND a passerine species. Therefore, an avian acu te oral toxicity test (OPPTS Guideline 850.2100) is required for passerine birds, as specified in 40 CFR Part 158 (CFR 40 2007). EFED suggests that SRRD request submission of a passerine study protocol for review by EFED prior to initiation of this study. If oral acute toxicity da ta are not submitted for passerines, EFED will assume acute risk for passerine species.

Acute Toxicity Studies with Fr eshwater Fish and Invertebrates

The available acute data for freshwater fish and invertebrates are based on static studies where only nominal test concentrations are available. Given the low solubility and tendency for fenbutatin-oxide to sorb, measured test concentrations are required in freshwater acute studies to provide reliable exposure concentrations and asso ciated measurement endpoints. Endpoints that
are based on nominal concentra tions may underestimate the toxici ty of fenbutatin-oxide due to its low solubility and propensity to sorb to the glass surfaces of test cont ainers. Therefore, an acute freshwater fish study with rainbow trout ( Oncorhyncus mykiss ) (OPPTS Guideline 850.1075) and an acute freshwater invert ebrate study with the water flea ( Daphnia magna ) (OPPT Guideline 1010) are required in order to address uncertain ties associated with endpoints
that are based on data from static tests and nomin al test concentrations. Both freshwater acute studies must be conducted under flow-through conditi ons and measured test concentrations must be provided.

Chronic Toxicity Studies with Estuar ine and Marine Fish and Invertebrates

Chronic toxicity data are not available for es tuarine and marine fish and invertebrates. According the Part 158 data requirements, chr onic data are required for estuarine fish and
invertebrates if the acute LC 50 

### value is < 1,000 μg/L. Given that the acute estuarine/marine fish and mysid ( Americamysis bahia ) LC 50 

### values are 20.8 μg/L and 2.8 μg/L, respectively, the chronic data requirements for estuarine/marine fish and invertebrates are not fulfilled. In

### 27 of 43 addition, estuarine/marine invertebrates ( i.e. , mysids and Eastern oysters) are more sensitive to fenbutatin-oxide on an acute exposure basis than the freshwater inve rtebrates tested; the reason(s) for the difference in toxicity is unclear . Because no toxicity da ta for chronic exposures
are available for estuarine/marine invertebrates an d toxicity data from freshwater invertebrates do not appear to be a good surrogate for measures of toxicity to this taxon, there is the potential
for adverse effects to estuarine/marine invertebra tes from chronic exposures to fenbutatin-oxide. Therefore a chronic mysid full life-c ycle study (OPPTS Guideline 850.1350) and estuarine/marine fish early life-stage toxicity test (OPPTS Guideline 850.1400) are required in order to fulfill the data requirements for estuarine/ marine invertebrates and fish, respectively. In the absence of chronic endpoints fo r estuarine/marine fish and i nvertebrates, EFED will assume
chronic risk to estuarine/mari ne fish and invertebrates.

Sediment Toxicity to Freshwater and Estuarine/Marine Benthic Invertebrates

Based on the persistence in and partitioning of fenbut atin-oxide to sediments, this pesticide has a propensity to sorb to particles and move to adjacent surface water through runoff of sedimentbound residues (erosion) followi ng high rain events. Accord ing to the Part 158 data requirements, chronic freshwater sediment toxi city testing with the technical grade active ingredient is required if the half-life of the pesticide in sediment is > 10 days in either the aerobic soil or aquatic metabolism studies, and if any of the following conditions exist:

• The soil partition coefficient (K d 

### ) is > 50.

• The log K OW 

### is > 3.

• The K OC 

### is > 1,000.

For fenbutatin-oxide, the aerobic soil metabolism half-life values range from 944 to 2,951 days,

K d 

### values range from 1,282 to 2,333 L/kg, and the log K OW 

### is 5.14; therefore, the requirements for chronic freshwater sediment toxicity testing are met. Sediment toxi city testing is required
with estuarine/marine inverteb rates if environmental concentr ations are expected to be significant based on its expected mobility pattern in either runoff or erosion. In addition, it is likely that estuarine/marine invertebrates may be more sensitive to fenbutatin-oxide as compared with freshwater invertebrates, based on the availa ble acute toxicity data. In order to fulfill the data requirements and reduce the uncertainties associ ated with a lack of sediment toxicity data, 28-day spiked sediment studies (with suitable range finding tests) shoul d be completed with fenbutatin-oxide per OPPTS Guidelines 850.1735 and 850.1740 for sediment dwelling freshwater and estuarine/marine invertebrates, re spectively. Measured con centrations of the test substance in the sediment, pore water, and overlyi ng water must be provided. In the absence of sediment toxicity testing data, EFED will assume risk to freshwater and estuarine/marine benthic
invertebrates.

Aquatic and Terrestrial Plant Studies

Toxicity data for vascular and non- vascular aquatic plants and terres trial plants are not available. Based on the 40 CFR Part 158 data requirements, Ti er I level non-target a quatic and terrestrial plant data are required for all in secticides. In add ition, available incident data for fenbutatinoxide shows two incident reports for plants, a nd potential phytotoxic e ffects associated with

### 28 of 43 fenbutatin-oxide are noted on the end-use product labels. Therefor e, this data gap must be filled,
and data for non-vascular and vascular aquatic plants (OPPTS Guidelines 850.4400 and 850.5400) and non-target terrestrial plant seedling emergence and vegetative vigor data (OPPTS Guidelines 850.4100 and 850.4150) are required for fenbut atin-oxide at the Tier 1 level. In the absence of Tier I data, EFED will assume risk to vascular and non-vascular aquatic plants and terrestrial and semi-aquatic plants.

8. References

Arnot, J. A. and F.A.P.C. Gobas. 2004. A food web bioaccumulation model for organic chemicals in aquatic ecosystems. Environmental Toxicology and Chemistry. 23(10):2343-2355.

CFR 40. 2007. Code of Federal Regulations 40 Parts 150 to 189. Protection of the Environment. U.S. Government Printing Office.

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA food-chain (Kenaga) nomogram, an inst rument for estimating pesticide residues on plants. Environ. Tox. Chem.

13:1383-1391.

Hoerger, F. and E. E. Kenaga, 1972. Pesticide Residues on Plants: Correlation of Representative Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.

Kashuba, R., Spatz, D. 2006 Memorandum to Steven Bradbury, Subject: Standard Soil Mobility Classification
Guidance

Ma, J. 2005. Differential sensitivity of three cyanob acterial and five green algal species to organotins and pyrethroids pesticides. Science of the Total Environment. 341: 109-117



### .

USEPA. 1993. Wildlife Exposure factors handbook. United States Environmental Protection Agency. Office of Research and Development. EPA/600/R-93/187.

U.S. Environmental Protection Agency (USEPA). 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of Research and Development, Washington, D.C. EPA/630/R-95/002F. April

1998. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759

USEPA. 2002. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version II. US Environmental Protection Agency, Washington DC. Online at: http://www.epa.gov/oppefed1/models water/input_guidance2_28_02.htm.

USEPA. 2004. Overview of the Ecological Risk Assessm ent Process in the Office of Pesticide Programs. U.S. Environmental Protection Agency, Of fice of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA. 2007. 40 CFR Part 158. Pesticides; Data Requ irements for Conventional Chemicals: Final Rule. 72 FR 60934. October 26, 2007.

USEPA. 2008. 73 FR 20642. Notice of Receipt of Requests to Voluntarily Cancel Certain Pesticide Registrations. [EPA-HQ-OPP-2008-0195; FRL-8358-5]. April 16, 2008.

### 29 of 43 USEPA. 2009a. ECOTOXicology Database. Office of Research and Development National Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent Ecology Division (MED). http://cfpub.epa.gov/ecotox/

USEPA. 2009b. Ecological Incident Information System. http://www.epa.gov/espp/consultation/ecoriskoverview.pdf

U.S. Fish and Wildlife Service (USFWS) and National Ma rine Fisheries Service (NMFS). 1998. Endangered Species Consultation Handbook: Procedures for Conducting Consultation and Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 1998.

SUBMITTED FATE STUDIES:

MRID: 40365801 Chang, W. (1987) Vendex (Fenbutatin Oxide): Product Identity and Composition: Laboratory Project ID: Y4332.A (ES). Unpublished study prepared by E. I. du Pont de Nemours and Co. 91 p.

MRID: 40790901 Horne, P. (1988) Hydrolysis of 119 Sn-Fenbutatin Oxide in Buffer Solutions of pH 5, 7 and 9: Laboratory Project ID AMR-923-87. Unpublished study prepared by E. I. du Pont de Nemours & Co. 35 p.

MRID: 40790902 Horne, P. (1988) Photodegradation of 119 Sn-Fenbutatin Oxide in Water: Laboratory Project ID AMR-924-87. Unpublished study pre- pared by E. I. du Pont de Nemours & Co., Inc. 34 p.

MRID: 40696403 Mucha, C.; Koeppe, M. (1988) Photodegradation of 119m Sn-Fenbutatin Oxide on Soil: Laboratory Project ID AMR925-87. Unpublished study pre- pared by E.I. du Pont de Nemours & Co., Inc. 43 p.

MRID: 40257001 Lee, P. (1980) Aerobic Soil Metabolism of 119 Sn-SD-14114: Shell Re- port No. TIR-22-002-80. Unpublished study prepared by Shell Development Co. 30 p.

MRID: 40257002 Lee, P. (1980) Anaer obic Soil Metabolism of 119 Sn-SD-14114: Shell Report No. TIR-22-110-79. Unpublished study prepared by Shell Development Co. 76 p.

MRID: 42074501 Marxmiller, R.; McClory, J.; Stanley, B. (1991) Fiel d Soil Dissipation of Vendex Miticide: Lab Project Number: AMR 1152-88. Unpublished study prepared by McKenzie Laboratories, Inc. 136 p.

MRID: 43336401 Goodyear, A. (1993) (Carbon 14) Fenbutatin Oxide: Ad sorption/ Desorption in Three Soils: Final Report: Lab Project Number: 579/127/1015: 579/127. Unpublished study prepared by Hazleton UK. 83 p.

MRID: 42896801 McClory, J.; Freeman, C.; Wetheringt on, J. (1993) Field So il Dissipation of Vendex M iticide: Fenbutatin-Oxide: Lab Project Number: AMR 1152-88. Unpublished study prepared by E. I. du Pont de Nemours and Co.; Mckenzie Lab., Inc. 222 p.

MRID: 40696404 Hutton, D. (1988) Dynamic Bluegill Sunfish Bioconcentr ation Study with Fenbutatin Oxide: Rept. No. 336-88. Unpublished study pre- pared by E.I. du Pont de Nemours & Co., Inc. 61 p.

### 30 of 43 SUBMITTED EFFECTS STUDIES:

MRID: 113073 Fink, R.; Beavers, J.; Grimes, J.; et al . (1978) Acute Oral LD50-- Bobwhite Quail: SD 14114: Project No. 109-119. Final rept. (Unpublished study received Apr 2, 1979 under 201-369; prepared by Wildlife Inte rnational, Ltd., submitted by Shell Oil Co., Washington, DC; CDL:098036-C).

MRID: 113074 Fink, R.; Beavers, J.; Grimes, J.; et al. (1978) Eight-day Dietary LC50--Mallard Duck: SD-14114: Project No. 109- 120. Final rept. (Unp ublished study received Apr 2, 1979 under 201-369; prep ared by Wildlife In ternational, Ltd., submitted by Shell Oil Co., Washington, DC; CDL:098036-D).

MRID: 41258901 Beavers, J.; Hoxter, K.; Corbitt, A.; et al. (1989) Vendex Techni- cal: A One-generation Reproduction Study with the Bobwhite ( Colinus virginianus ): Wildlife International Ltd. Project No. 112-201. Unpublished study prepared by Dupont Haskell Labora tory. 155 p.

MRID: 41258902 Beavers, J.; Hoxter, K.; Corbitt, A.; et al. (1989) Vendex Techni- cal: A One-generation Reproduction Study with the Mallard ( Anas platyrhynchos ): Wildlife International Ltd. Project No. 112-202. Unpublished study prepared by Dupont Haskell Laboratory. 152 p.

MRID: 113076 Johnson, W.; Jones, T. (1971) Static Ac ute Toxicity of SD 14114 to Bluegill. (U.S. Fish and Wildlife Service, Fishpesticide Re- search Laboratory; unpublished study; CDL:098036-I).

MRID: 40473506 Hutton, D. (1987) Static Acute 96-hour LC50 of Technical Vendex to Rainbow Trout, Oncorhynchus mykiss (formerly Salmo gairdneri ): Haskell Laboratory Report No. 327-87: MR 4581-472. Unpublished study prepared by Haskell Laboratory for Toxicology and Industrial Medicine. 10 p.

MRID: 40473507 Hutton, D. (1988) Static Acute 96-hour LC50 of Vendex 4L to Rainbow Trout: Haskell Laboratory Report No. 707- 87: MR 4581-540. Unpublished study prepared by Hasekll Laboratory for Toxicology.

MRID: 40473508 Hutton, D. (1988) Static Acute 96-hour LC50 of Vendex to Bluegill Sunfish: Haskell Laboratory Report No. 13-88: MR 4581-540. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medicine. 14 p.

MRID: 97420 Parrish, P.R. (1973) Letter sent to John Harrison date d Aug 15, 1973 ?Test conditions of SD 14114|. (U.S. Environmental Protection Agency, Gu lf Breeze Environmental Research Laboratory; unpublished study; CDL:093941-P).

MRID: 113077 Sanborn, J.; Nugent, K.; Reeves, G.; et al. (1979) A Stud y of the Acute (96 Hour) Toxicity of Vendex Miticide to Daphnia magna . (Unpublished study received Apr 2, 1979 under 201-369; submitted by Shell Oil Co., Washington, DC; CDL:098036-J).

MRID: 40473509 Hutton, D. (1987) Daphnia magna Static Acute 48-hour EC50 of Technical Vendex: Haskell Laboratory Report No. 316-87: MR 4581- 501. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medicine. 10 p.

### 31 of 43 MRID: 40473510 Hutton, D. (1987) Fed Daphnia magna Static Acute 48-hour LC50 of Technical Vendex: Haskell Laboratory Report No. 325-87: MR 4581-501. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medicine. 10 p.

MRID: 40473511 Hutton, D. (1988) Daphnia magna Static Acute 48-hour EC50 of Vendex 4L: Haskell Laboratory Report No. 12-88: MR 4581-540. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medicine. 13 p.

MRID: 113046 Parrish, P. (1973) Letter sent to J. Harrison dated Aug 15, 1973 (Toxicity--aquatic life: SD 14114, an organotin miticide). (U.S. Envir. Pr otection Agency, Gulf Breeze Envir. Research Lab.; unpublished study; CDL:094519-Z).

MRID: 40590506 Boeri, R. (1988) Static Acute Toxicity of Haskell Sample No. 16,879 to the Sheepshead Minnow, Cyprinodon variegatus: Project No. D0887. Unpublished study prepared by Enseco Inc. 21 p.

MRID: 40590507 Boeri, R. (1988) Static Acute Toxicity of Haskell Sample No. 16,879 to Embryos and Larvae of the Eastern Oyster Crassostrea virginica : Project No. D0787. Unpublished study prepared by Enseco Inc. 21 p.

MRID: 40590508 Boeri, R. (1987) Static Acute Toxicity of Haskell Sample No. 16,879 to the Mysid, Americamysis (formerly Mysidopsis) bahia : Project No. D0987. Unpublished study prepared by Enseco Inc. 22 p.

MRID: 41077501 Boeri, R. (1988) Static Acute Toxicity of Haskell Sample No. 16,879 to Embryos and Larvae of the Eastern Oyster Crassostrea virginica . Enseco Marblehead Laboratory Project D0787: HLO 96-88. Unpublished study prepared by Enseco, Inc. 21 p.

MRID: 41077502 Boeri, R. (1987) Static Acute Toxicity of Haskell Sample Number 18,879 to the Mysid, Americamysis ( fomerly Mysidopsis ) bahia : Enseco Marblehead Labora-tory Project D0987: Du pont HLO 96-88. Unpublished study prepared by Enseco, Inc. 22 p.

MRID: 41483301 Boeri, R.; Ward, T. (1990) Acute Flow-through Toxicity of Vendex to the Sheepshead Minnow, Cyprinodon variegatus : Lab Project No.: HLO-78-90. Unpublished study prepared by Resource Analysts, Inc., EnviroSystems Div. 30 p.

MRID: 40473512 Hutton, D. (1987) Early Life Stage Toxicity of Technical Vendex to Rainbow Trout, Oncorhynchus mykiss (formerly Salmo gairdneri ): Haskell Laboratory Report No. 460-87: MR 4581-472. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medicine. 19 p.

MRID: 40525901 Hutton, D. (1988) Chronic Toxicity of Technical Vendex to Daphnia magna : Rept. No. 94-88. Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc. 20 p.

MRID: 40916301 Hutton, D.; Hardesty, P. (1987) Supplement #1 to Early Life Stage Toxicity of Technical "Vendex" to Rainbow

Trout Oncorhynchus mykiss (formerly (Salmo gaird-neri): Haskell Laboratory Report No. 460-87: MR 4581-472. Un- published study prepared by E. I. du Pont de Nemours & Co., Inc. 84 p.

### 32 of 43 MRID: 41551401 Boeri, R.; Ward, T. (1990) Early Life Stage Toxicity of Vendex to the Sheepshead Minnow, Cyprinodon variegatus : Lab Project No.: HLO 303-90. Unpublished study prepared by EnviroSystems Div. 182 p.

MRID: 41551402 Boeri, R.; Ward, T. (1990) Life-cycle Toxicity of Vendex Technical to the Mysid, Americamysis (formerly Mysidopsis ) bahia : Lab Project Number: HLO 304-90. Unpublished study prepared by EnviroSystems Div. 318 p.

MRID: 42872101 Wallace, M.; Jenkins, J.; Sutherland, C.; et al. (1993) An Aquatic Residue Monitoring Study of Vendex 4L in Florida Citrus Groves: Amended Report I: Lab Project Number: 112-194: AMR 1165-88. Unpublished study prepared by McKenzie Labs, Inc. and Wildlife International Ltd. 764 p. MRID: 30344 Cannelongo, B.F.; Sabol, E.J.; Sabol, R.J.; et al. (1 979) Rat Acute Oral Toxicity : Project No. 1367-79. (Unpublished study received Jan 10, 1 980 under 201-412; prepared by Stillmeadow, Inc., sub- mitted by Shell Chemical Co., Washington, D.C.; CDL:241616-D).

MRID: 37577 Natoff, I.L.; Stevenson, D.E. (1973) Toxicity Studies on the Pes- ticide SD 14114: Acute Oral Toxicity Studies in the Mouse, Rat and Rabbit of the Me tabolite SD 31723: TLGR. 0037.73. (Unpub- lished study received on unknown date under 4F1492; prepared by She ll Research Ltd., submitted by Shell Chemical Co., Washing- ton, D.C.; CDL:093941-D).

MRID: 113031 Wallgren, H.; Sammalisto, L.; Suomalainen, H. (1963) Physiological effect of phenethyl alcohol. J. Inst. Brew. 69:418-420. (Also In unpublished subm ission received Jun 25, 1974 under 4F 1492; submitted by Shell Chemical Co., Washington, DC; CDL:094519-K).

MRID: 113038 Samuels, G. (1972) Toxicity Test 1: ?Mouse|. (Unpublished study received Ju n 25, 1974 under 4F1492; prepared by Tunstall Laboratory, Eng., submitted by Shell Chemical Co., Washington, DC; CDL:094519-R).

MRID: 113048 Simpson, B.; Dix, K.; Stevenson, D. (1972) Toxicity Studies on the Pesticide SD 14114: Acute and 90 Day Feeding Studies in the Rat of the Metabolite SD 31723: TLGR.0023.72. (Unpublished study received Jun 25, 1974 under 4F1492; prepared by Tunstall Laboratory, Eng. and Sittingbo urne Laboratories, Eng., submitted by Shell Chemical Co., Washington, DC; CDL:094519-AB).

MRID: 40473504 Sarver, J. (1988) Acute Oral Toxicity Study with IN Y4332-5 in Male and Female Rats: Haskell Laboratory Report No. 742-87: Medical Research No. 4581-545. Unpublished study prepared by Dupont Haskell Laboratory for Toxicology and Industrial Medi- cine. 38 p.

MRID: 40709801 Dougherty, K. (1988) The Acute Oral Toxicity of CC-16244 (SX-1786) in Adult Male and Female Rats: Proj. ID CEHC 2871. Unpublished study prepared by Chevron Environmental Health Center, Inc. 62 p.

MRID: 40709901 Dougherty, K. (1988) The Acute Oral Toxicity of CC-16243 (SX-1793) in Adult Male and Female Rats: Project ID: CEHC 2878; S-3090. Unpublished study prepared by Chevron Environmental Health Center, Inc. 43 p.

MRID: 42783804 Mallory, V. (1993) Acute Exposure Oral Toxicity in Ra ts with TD2336-1: Lab Proj ect Number: PH 402-ANA-005- 92. Unpublished study prepared by Pharmakon Research International, Inc. 61 p.

### 33 of 43 MRID: 43718104 Finlay, C. (1995) Acute Oral Toxicity Study with DPX-Y4332-48 (Vendex 50 WP) in Male and Female Rats: Lab Project Number: HLR 73-95: 10049-001. Unpublished study prepared by DuPont's Haskell Lab for Toxicology and Industrial Medicine. 23 p.

MRID: 37584 Eisenlord, G.; Loquvam, G.S.; Anderson, R.; et al. (1973) Results of Reproduction Study of Rats Fed Diets Containing SD14114-U over Three Generations: Report No. 33. (Unpublished study received on unknown date under 4F1492; prepared by Hine Labora- tories, Inc., submitted by Shell Chemical Co., Washington, D.C.; CDL:093941-K).

MRID: 41540601 Bentley, K. (1990) Reproductive and Fertility Effects with Vendex Technical (IN Y4332-5) Multigeneration Reproduction Study in Rats: Lab Project Number: 128-90: 8388-001. Unpublished study prepared by E. I. du Pont de Nemours and Co./Haskell Laboratory. 1262 p.

MRID: 46223005 Moore, G. (2004) Acute Oral Toxicity Up and Down Procedure in Rats: S-11046 Tox# T-313. Project Number: 14338, P320/UDP. Unpublished study prepared by Product Safety Labs. 15 p.

MRID: 46295508 Moore, G. (2004) Acute Oral Toxicity Up and Down Procedure in Rats: S-11045 Tox# T-314. Project Number: P320/UDP, 14747. Unpublished study prepared by Product Safety Labs. 15 p.34 of 43Appendix A. Fenbutatin-oxide and DegradatesChemical(CAS Number)MWStructureSMILESFenbutatin-oxide(13356-08-6)1052.67[Sn](CC(C)(C)c1ccccc1)(CC(C)(C)c2ccccc2)(CC(C)(C)c3ccccc3)O[Sn](CC(C)(C)c4ccccc4)(CC(C)(C)c5ccccc5)CC(C)(C)c6ccccc61,3-dihydroxy-1,1,3,3-tetrakis(2-methyl-2-phenylpropyl)distannoxane(SD 31723)(162476-39-3)419.15[Sn](CC(C)(C)c1ccccc1)(CC(C)(C)c2ccccc2)(O)(O)2-methyl-2-phenylpropylstannonic acid(SD33608)(162476-40-6)284.93[Sn](CC(C)(C)c1ccccc1)(=O)(O)

### 35 of 43 Appendix B. Data Call-In Tables

Guideline Number: 835.4300 Study Title: Aerobic Aquatic Metabolism Study Rationale for Requiring the Data No study has been submitted to support the regi stration review of fenbutatin-oxide. Per 40 CFR 158, Subpart N, this study is part of the required environmental fate data. Practical Utility of the Data

How will the data be used? Based on the available data, fenbutatin-oxide is very highly toxic to freshwater and estuarine/ marine fish. In order to reliably estimate the con centrations to which fish and invertebrates may be exposed, aerobic aquatic metabolis m data are necessary inputs to the PRZM/EXAMS model. Additionally, the data will identify any transformation products that may occur.

How could the data change the Agency’s decisi on or impact the Agency’s future decisionmaking? If data indicate that fenbutatin-oxide persists in aerobic aquatic environments, additional use precautions and/or restrictions may be necessary. In addition, the lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

Guideline Number: 835.4400 Study Title: Anaerobic Aquatic Metabolism Study Rationale for Requiring the Data No study has been submitted to support the regi stration review of fenbutatin-oxide. Per 40 CFR 158, Subpart N, this study is part of the required environmental fate data. Practical Utility of the Data

How will the data be used? Based on the available data, fenbutatin-oxide is very highly toxic to freshwater and estuarine/
marine fish and invertebrates. In order to relia bly estimate the concentrations to which fish and invertebrates may be exposed, anaerobic aquatic metabolism data are necessary inputs to the PRZM/EXAMS model. Additionally, the data w ill identify any transformation products that may

occur.

How could the data change the Agency’s decisi on or impact the Agency’s future decisionmaking? If data indicate that fenbutatin-oxide persists in anaerobic aquatic environments, additional use precautions and/or restrictions may be necessary. In addition, the lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

Guideline Number: 850.1730 Study Title: Fish BCF Study Rationale for Requiring the Data In the submitted study (MRID 406964-04), the accumu lation of fenbutatin-oxide in the various tissue fractions did not plateau (equilibrate) duri ng the 28-day exposure period; therefore, the actual BCF's may be significantly higher than those calculated.

### 36 of 43 Practical Utility of the Data

How will the data be used? Given the high log K

ow there is a potential for bioconcentration and bioaccumulation. Reliable BCFs are needed to assess the potential exposure and risk associated with food chain transfer (bioaccumulation) of fenbutatin-oxide in aquatic prey and the subsequent risks to mammals and birds. Depending on the measured BCFs, the predicted risk for piscivorous mammals/bird via KABAM modeling may be underestimated or overestimated.

How could the data change the Agency’s decisi on or impact the Agency’s future decisionmaking?
If data indicate that fenbutatin-oxide accumulat es in tissue at higher levels, additional use precautions and/or restrictions may be necessary. In addition, if future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatinoxide “may affect” mammals and birds that feed on aquatic organisms (e.g ., piscivores) directly (and listed species from other taxa indirectly), and use of fenbutatin-oxide may need to be restricted in areas where listed piscivorous mammal and bird species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

Guideline Number: 850.2100 Study Title: Avian Acute Oral Toxicity Test Rationale for Requiring the Data Acceptable acute avian oral toxicity data we re submitted for exposures of bobwhite quail to fenbutatin-oxide; however, data are not availabl e for a passerine species, which are now required under the 40 CFR Part 158 (CFR 40 2007) data requi rements for conventional pesticides. The Part 158 data requirements specify that acute avian oral toxicity data be submitte d for either mallard duck or bobwhite quail AND a passerine species. Therefore, an avian oral toxicity test is required for passerine birds, as specified in OPPTS Guideline 850.2100 ( http://www.epa.gov/opptsfrs/publicati ons/OPPTS_Harmonized/850_Ecological_E ffects_Test_Guidelines/Drafts/850-
2100.pdf 

### ) . A passerine study protocol must be submitte d for review by the Agency prior to initiation of this study. Practical Utility of the Data

How will the data be used? Acute avian oral toxicity data for passerine sp ecies will be used to refine the screening-level assessment by determining whether there are diffe rences in avian species sensitivity to fenbutatinoxide between passerines and upland game species. Although the currently submitted data indicate that fenbutatin-oxide is practically non-toxic to bi rds on an acute oral and sub-acute dietary exposure basis, the extent to which toxicity may occur in passerines is unknown. If oral acute toxicity data are not submitted for passerines, risk will be assumed for all passerine species.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may affect ” birds directly (and listed species from other taxa indirectly), and use of fenbutatin-oxide may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

### 37 of 43 Guideline Number: 850.1075 and 850.1010 Study Title: Freshwater Fish – Acute Toxicity and Freshwater Invertebrates - Acute Toxicity Rationale for Requiring the Data Although acute freshwater fish and invertebrate da ta have been submitted for fenbutatin-oxide, the
available data are based on static studies where onl y nominal test concentrations are available. Based on the low solubility and tendency for fenbutatin-oxide to sorb, measured test concentrations from flow-through studies are required to provide reliable exposure concentrations and associated measurement endpoints. Endpoints that are based on nominal concentrations may underestimate the toxicity of fenbutatin-oxide due to its low solub ility in water and propensity to sorb to the glass surfaces of test containers. Therefore, acute freshwater fish and invertebrate studies (OPTTS Guidelines 850.1075 and 850.1010, respectively; ( http://www.epa.gov/opptsfrs/publications/OPPTS_Ha rmonized/850_Ecological_Effects_Test_Guid elines/Drafts/850-1075.pdf and http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-1010.pdf )) should be conducted with rainbow trout ( Oncorhyncus mykiss ) and Daphnia magna under flow-through conditions, a nd measured test concentrations must be provided. Practical Utility of the Data

How will the data be used? The data are necessary to reduce uncertainties associated with acute freshwater endpoints that may potentially underestimate fenbutatin-oxide toxicity to freshwater animals. In the absence of this data, endpoints based on nominal test concentrations will be used with the caveat that toxicity is likely to be underestimated. Because the extent to which acute toxicity may be underestimated for freshwater animals would be unknown, the Agency would presume acute risk to listed and nonlisted freshwater fish and invertebrates.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may affect ” freshwater fish and invertebrates directly (and listed species from other taxa indirectly), and use of fenbutatin-oxide may need to be restricted in areas where listed species could be exposed. Th e lack of these data will limit the flexibility the Agency and registrants have in coming into co mpliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

Guideline Number: 850.1350 Study Title: Mysid Chronic Toxicity Test Rationale for Requiring the Data An acceptable chronic full life-cycle estuarine/marine i nvertebrate toxicity test with mysid shrimp is required under 40 CFR Part 158 (CFR 40 2007) data requirements for conventional pesticides (72 FR 60934; USEPA 2007c) because the available acute mysid LC 50 value is <1 mg/L. In addition, the available acute toxicity data for invertebrates indicate that estuarine/marine invertebrates are an order of magnitude more sensitive to fenbutatin-oxide than freshwater invertebrates. The chronic toxicity test with mysid shrimp ( Americamysis bahia ) (OPPTS Guideline 850.1350; http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-1350.pdf ) must be submitted for fenbutatin-oxide to satisfy the guideline requirement. These data are important in determin ing whether chronic exposure to fenbutatin-oxide may potentially impact the life-cycle of estua rine/marine invertebrates (crustaceans).

### 38 of 43 Practical Utility of the Data

How will the data be used? These data are necessary to characterize the potential direct chronic effects of fenbutatin-oxide to
estuarine/marine invertebrates. The data from th e study will be used to address the uncertainty regarding the potential for enhanced sensitivity of est uarine/marine invertebrate s to fenbutatin-oxide. In the absence of chronic endpoints for estuarine/ marine invertebrates, risk will be presumed.

How could the data change the Agency’s decisi on or impact the Agency’s future decisionmaking? If the data indicate that fenbutatin-oxide poses a si gnificant chronic risk to invertebrates inhabiting estuarine/marine water bodies, the Agency may explor e additional options to minimize the risk of
fenbutatin-oxide to estuarine/marine invertebrates. If future endangered sp ecies risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may affect” estuarine/marine invertebrates directly (and listed species from other taxa indirectly), and use of fenbutatin-oxide may need to be restricted in ar eas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are

unnecessary.

Guideline Number: 850.1400 Study Title: Saltwater Fish, Early Life-Stage Toxicity Test Rationale for Requiring the Data
Chronic toxicity data are not available for estuarine and marine fish. An acceptable early life-stage toxicity test with estuarine/marine fish is required under 40 CFR Part 158 (CFR 40 2007) data requirements for conventional pesticides (72 FR 60934; USEPA 2007c) because the available acute sheepshead minnow LC 50 value is <1 mg/L. The early lif e-stage test with sheepshead minnow (OPPTS Guideline 850.1400; http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-1400.pdf ) must be submitted for fenbutatin-oxide to satisfy the guideline requirement. These data are important in determin ing whether chronic exposure to fenbutatin-oxide may potentially impact early life stages of estuarine/marine fish. Practical Utility of the Data

How will the data be used? The estuarine/marine early life stage fish data woul d allow the Agency to refine its screening-level risk assessment by considering ch ronic exposure and potential toxicity and risk to estuarine/marine fish. In addition, these data would allow the Ag ency to determine whether chronic exposure to fenbutatin-oxide may potentially impact listed species in estuarine/marine environments, either by direct effects on fish or by indirect effects via re duction of prey. In the absence of chronic toxicity data for estuarine and marine fish, risk will be presumed.

How could the data impact the Agency’s future decision-making? If the data indicate that fenbutatin-oxide poses a significant chronic risk to fish inhabiting estuarine/marine water bodies, the Agency may expl ore additional decision options to minimize the
risk of fenbutatin-oxide to estuarine/marine fish . If future endangered species risk assessments are performed without these data, the Agency would have to rely on an acute-to-chronic ratio based on freshwater fish data, which may lead to a “may affect” determination for estuarine/marine fish directly (and listed species from other taxa indir ectly). Such a determination may result in a
restriction of fenbutatin-oxide use in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and regi strants have in coming into compliance with the

### 39 of 43 Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are

unnecessary.

Guideline Number: 850.1735 and 850.1740 Study Title: Whole Sediment Toxicity Test ing with Freshwater and Marine Invertebrates Rationale for Requiring the Data
Fenbutatin-oxide has a propensity to sorb to sed iment and move to adjacent surface water via runoff of sediment-bound residues following high rain events. Chronic sediment toxicity data are required for fenbutatin-oxide because its aerobic soil metabolism half-life, log K OW , and K d values exceed the criteria for chronic sediment testing set forth in the 40 CFR Part 158 (CFR 40 2007) data requirements for conventional pesticides (72 FR 6 0934; USEPA 2007c). In order to fulfill the data requirements and reduce the uncertainties associated with a lack of sediment toxicity data, 28-day spiked sediment studies (with suitable range findi ng tests) should be completed with fenbutatinoxide per OPPTS Guidelin es 850.1735 and 850.1740 ( http://www.epa.gov/opptsfrs/publications/OPPTS_Ha rmonized/850_Ecological_Effects_Test_Guid elines/Drafts/850-1735.pdf and http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-1740.pdf ) for sediment dwelling freshwater and estuarine/marine invertebrates, respectively. Measured concentrations of the t est substance in the sediment, pore water, and overlying water must be provided. Practical Utility of the Data

How will the data be used? The chronic sediment toxicity data would allow th e Agency to reduce uncerta inties associated with the potential for enhanced exposure to fenbutatin-oxi de that is sorbed to sediment and subsequent
risk to freshwater and estuarine/marine benthic inve rtebrates. In addition, these data would allow the Agency to determine whether chronic exposure to fenbutatin-oxide may potentially impact listed benthic species in estuarine/marine environments, either by direct effects on fish or by indirect effects via reduction of prey. In the absence of sediment toxicity testing data, EFED will assume
risk to freshwater and estuarine/marine benthic invertebrates.

How could the data impact the Agency’s future decision-making? If the data indicate that fenbutatin-oxide poses a significant risk to freshwater and estuarine/marine benthic invertebrates via exposure to sediment, th e Agency may explore additional decision options
to minimize the risk of fenbutatin-oxide to fresh water and estuarine/marine benthic invertebrates. If future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may a ffect” freshwater and estuarine/marine benthic invertebrates directly (and listed species from other taxa indirectly), and use of fenbutatin-oxide may
need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are unnecessary.

Guideline Number: 850.4400 and 850.5400 Study Title: Aquatic plant toxicity (Tier I) Rationale for Requiring the Data Fenbutatin-oxide toxicity data for vascular and non-vascular aquatic plants are not available. Based

### 40 of 43 on the 40 CFR Part 158 data requirements, Tier I le vel non-target aquatic plant data are required for all insecticides. Therefore, non-target aquatic pl ant data for algae and vascular plants per OPPTS
Guidelines 850.4400 and 850.5400 ( http://www.epa.gov/opptsfrs/publications/OPPTS_Ha rmonized/850_Ecological_Effects_Test_Guid elines/Drafts/850-4400.pdf and http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-5400.pdf ) are required for fenbutatin-oxide at the Tier I level. Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies w ill be used to estimate potential risks to aquatic vascular and non-vascular plants associated with th e use of fenbutatin-oxide. The data will reduce
uncertainties associated with the current risk assessment for aqua tic plants and will improve the Agency’s understanding of the potential effects of fe nbutatin-oxide on aquatic plants. In the absence of Tier I data, risks for both vascular and no n-vascular aquatic plants will be presumed.

How could the data impact the Agency’s future decision-making? Because aquatic vascular and non-vascular plants form the basis of the food chain for aquatic communities and significantly contribute to overa ll water quality, a solid understanding of the potential risks to aquatic plants is essential fo r sound environmental risk management decisionmaking. Without aquatic plant data for fenbutatin-o xide, the Agency cannot determine if the current application rates of fenbutatin-oxide may result in direct adverse effects to aquatic plants and/or indirect effects resulting from reduction in the prey base and/or loss of habitat/cover. If future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may affect” aquatic plants directly (and listed species from other taxa indirectly via reduction in prey base and/or habita t), and use of fenbutatin -oxide may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

Guideline Number: 850.4100 and 850.4150 Study Title: Terrestrial plant seedling emergen ce and vegetative vigor toxicity (Tier I) Rationale for Requiring the Data Fenbutatin-oxide toxicity data for terrestrial plan ts are not available. Based on the 40 CFR Part 158 data requirements, Tier I level non-target terrestri al plant data are required for insecticide end-use products at the maximum application rate. In add ition, available incident data for fenbutatin-oxide shows two incident reports for terrestrial plants , and potential phytotoxic effects associated with fenbutatin-oxide are noted on the end-use product la bels. Therefore, non-target terrestrial plant seedling emergence and vegetative vigor data per OPPTS Guidelines 850. 4100 and 850.4150 ( http://www.epa.gov/opptsfrs/publications/OPPTS_Ha rmonized/850_Ecological_Effects_Test_Guid elines/Drafts/850-4100.pdf and http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guide lines/Drafts/850-4150.pdf ) are required for fenbutatin-oxide at the Tier I level to fulfill the data requirement.

### 41 of 43 Practical Utility of the Data

How will the data be used? Data from Tier I terrestrial plant seedling emerge nce toxicity studies will be used to estimate potential risks to terrestrial and semi-aquatic plants associated with the use of fenbutatin-oxide. The
data will reduce uncertainties associ ated with the current risk assess ment for terrestrial and semiaquatic plants and will improve the Agency’s u nderstanding of the potential effects of fenbutatinoxide on terrestrial and semi-aquatic plants. In th e absence of Tier I data, risks for terrestrial and semi-aquatic plants will be presumed.

How could the data impact the Agency’s future decision-making? Because terrestrial and semi-aquatic plants form the basis of the food chain for terrestrial habitats, comprise riparian habitat which plays a key role in water quality, and significantly contribute to habitat integrity including critical habitat for liste d species, an understanding of the potential risks to terrestrial and semi-aquatic plants is essential fo r sound environmental risk management decisionmaking. Without terrestrial plant data for fenbutatin-oxide, the Agency cannot determine if the current application rates of fenbutatin-oxide may resu lt in direct adverse effects to terrestrial plants and/or indirect effects resulting from reduction in the prey base and/or loss of habitat/cover. If future endangered species risk assessments are performed without these data, the Agency would have to assume that fenbutatin-oxide “may affect” terrestrial and semi-aquatic plants directly (and listed species from other taxa indirectly via reduction in prey base and/or habitat), and use of fenbutatin-oxide may need to be restricted in ar eas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for fenbutatin-oxide which are unnecessarily severe.

### 42 of 43 Appendix C. Summary of Previous Assessments

TYPE OF ASSESSMENT DATE USE(S ) ASSESSED RATE(S)/
APPL.
Lb a.i./A

New Use (Vendex 50WP) 1976 Strawberries 0.5

EUP (Vendex 50WP) 1977 Almonds Grapes 1.25

1

New use (Vendex 50WP) 1980 Almonds Grapes
Peaches
Plums

Prunes
Cherries 1.25

1.25

1

1

1

1.5

New Use (Vendex 50WP) 1981 Papaya 1

Section 18 (HI) 1981 Papaya 1

New Product (old uses) (Vendex 4L) 1982 Cherries
Plums

Prunes 1.5

1

1

New Use (Vendex 50WP) 1982 Walnuts

Pecans NS

Registration Standard (Vendex 50WP) 1986 Almond Apple Cherry
Citrus Eggplant Grapes Papaya
Peach

Pear

Pecan
Plum Strawberry
Walnut
Ornamentals 2 (max)

Section 18 (OR) (Vendex 4L) 1986 Raspberries 1

Section 18 (OR) (Vendex 4L) 1986 Raspberries 1

Section 18 (CA) (Vendex 4L) 1987 Marigolds 0.5

Section 18 (CA) (Vendex 4L) 1987 Watermelon 1

Section 18 (CA) (Vendex 4L) 1988 Marigolds 0.5

### 43 of 43 TYPE OF ASSESSMENT DATE USE(S ) ASSESSED RATE(S)/
APPL.
Lb a.i./A

New Use (OR and WA) (Vendex 50WP) 1988 Raspberries 2

New Use (Vendex 50WP) (Vendex 4L) 1989 Cucumbers NS

Section 18 (CA) (Vendex 50WP) 1989 Sweet corn 1

Section 18 (WA) (Vendex) 1989 Hops 1.5

Section 18 (CA) 1991 Watermelon 1

RED 1994 Almond Apple
Citrus Grapes Cherry Eggplant
Nectarine Papaya
Peach

Pear

Pecan
Plum

Prune Raspberry Strawberry
Walnut
Christmas tree
Ornamentals 2 (max)

Drinking Water Assessment (for the TRED) 2001 Modeled FL Citrus 2

New Use (Vendex 50WP) 2007 Pistachios 1.25