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Problem Formulation for the 

Environmental Fate, Ecological Risk, Endangered 

Species, and Drinking Water Assessments 

in 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 
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Table of Contents 

1. Purpose.........................................................................................................4 

2. Problem Formulation ..................................................................................................................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 
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1. Purpose 

The purpose of this problem formulation is to provide 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, respectively, and are applied post-emergence via ground, 

aerial, or orchard airblast application when mites first appear. This document will provide a plan 

for analyzing data on fenbutatin-oxide and for conducting relevant environmental fate, ecological 

risk, endangered species and drinking water assessments for its registered uses. Additionally, this 

problem formulation is intended to identify data gaps, uncertainties, and 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, Fungicide, and Rodenticide Act (FIFRA), all pesticides distributed 

or sold in the United States generally must be registered by EPA. In determining whether a 

pesticide can be registered in the U.S., EPA evaluates its safety to non-target species based on a 

wide range of environmental and health effects studies. In 1996, FIFRA was amended by the 

Food Quality Protection Act, and EPA was mandated to implement a new program for the 

periodic review of pesticides, i.e., Registration Review 

(http://www.epa.gov/oppsrrd1/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 Registration Review program pursuant to Section 3(g) 

of FIFRA, the Agency is beginning its evaluation of fenbutatin-oxide to determine whether it 

continues to meet the FIFRA standard for registration. This problem formulation for the 

environmental fate, ecological risk, endangered species, and drinking water assessment chapter 

in support of the Registration Review is intended 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 addressed in a Reregistration Eligibility 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 Decision (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 risks of concerns from exposure to fenbutatinoxide in food or drinking water. Potential ecological risks associated with fenbutatin-oxide were 

not assessed as part of the TRED action. Other environmental risk assessments for fenbutatinoxide which predate 1994 include assessments for six Section 3 new uses, one Experimental Use 

Permit, one Registration Standard, nine Section 18 emergency exemptions, and one New Product 

(Vendex® 4L in 1982, no longer active). 

The most comprehensive recent assessment of ecological risks associated with fenbutatin-oxide 

was completed in August 2007 as part of Section 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 with all registered fenbutatin-oxide uses were assessed because 

previous assessments had not included the highest 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 the potential for adverse effects on 

freshwater fish, estuarine/marine fish, and estuarine/marine invertebrates after both acute and 

chronic exposure; freshwater invertebrates after acute exposure; and birds and mammals 

following chronic exposure. Based on the available honey bee data, a label statement to protect 

foraging honey bees was not required. However, because fenbutatin-oxide is an acaricide, it was 

acknowledged that some terrestrial invertebrates (particularly spiders 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 incident reports, and an 

absence of plant toxicity data, risks to aquatic and terrestrial plants 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 dietary exposure for the new use on pistachios. 

Two previously registered fenbutatin-oxide end-use products, Orthonex® (Registration number 

239-2594) and Ortho® Systemic Insect Killer (Registration 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 Registration Review for fenbutatin-oxide. 

A complete listing of previous risk assessments and their determinations is provided in 

Appendix C.
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3. Stressor Source and Distribution 

3.1. Mechanism of Action 

Fenbutatin-oxide is a non-systemic organotin acaricide that inhibits adenosine triphophate (ATP) 

synthase resulting in disruption of cellular respiration (i.e., oxidative phosphorylation). This 

affects metabolic processes and energy 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 registered in the United States in 

1974. The first end-use product was registered in 1975 for use on apples, pears, and some citrus 

crops. Since that time, several other food crops and outdoor and greenhouse ornamental uses 

have been added to the labels. There are two active Section 3 products containing fenbutatinoxide: ProMITE® 50WP (Registration number 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 dispersible 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 use products. The maximum yearly application rate specified on the 

label for non-residential uses is 8 lb a.i./acre (established landscape ornamentals). The maximum 

yearly application rate for outdoor ornamentals, however, is not specified on the label. 

Therefore, the yearly application rate for this use 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-oxide indicates that the average 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 estimates, a retreatment interval (RTI) of approximately 8 days 

was estimated (365 days/year / (63 lbs 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 fenbutatin-oxide uses, along with their respective 

methods, rates, and any geographic limitations are defined in 

Table 1. Figure 1 below depicts the national distribution of fenbutatin-oxide agricultural usage 

and indicates that use on citrus, almonds, apples 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. 
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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 NS3

 22 NS3

Established landscape ornamentals 

(commercial application to trees, shrubs, 

flowering ornamentals, bedding plants, 

annuals, and perennials) 1

Ground 4 

(per year) 

22

 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 Canadensis, Camellia japonica, Pellaea rotundifolia, 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 H2O/acre is applied. 3

 In lieu of other data, the number of applications per year will be set to 45, with a RTI of 8 days, yielding a 

maximum annual application rate of 90 lbs a.i./acre. 
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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 physical, chemical, fate and transport characteristics associated 

with fenbutatin-oxide are summarized in Table 2. 

Table 2. General chemical and environmental 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 C60H80O1Sn2 NA NA 
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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 

(KOW) 

1.4 x 105 

(log KOW=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 (days) 110, pH=7 40790902 Acceptable 

Soil Photolysis half-life (days) 128 (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 Kd; 

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, BCF 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 degrade in the environment and is likely to persist. There is no 

evidence of hydrolysis of fenbutatin-oxide. The compound does not appear to readily degrade 

by soil photolysis, or under aerobic 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 sediment. During the anaerobic soil 

metabolism study (MRID 40257002) there appeared to be a decrease in fenbutatin-oxide 

between initiation of anaerobic conditions and the end of the study (60 days post initiation of 

anaerobic conditions). However, no pattern of degradation could be established and no 

degradation rate could be estimated. In terrestrial field dissipation studies, concentrations of 

fenbutatin-oxide increased after multiple applications 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 degradate 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 that aqueous photolysis would be limited to clear 
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shallow waters. Additionally, the degradates SD 31723 and 2-methyl-2-phenylpropyl stannonic 

acid (SD 33608) were identified during the field dissipation studies. Consistent with the 

laboratory data showing that the compound is relatively stable to both 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 air (0.4 hours, EPISuite v 4.0), transport via volatilization 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 Kow =5.14), bioconcentration and 

bioaccumulation in aquatic receptors and consumption 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 the Overview Document (USEPA 2004), the risk 

assessment for fenbutatin-oxide relies on a surrogate species approach. Toxicological data 

generated from surrogate test species, which are intended to be representative of broad 

taxonomic groups, are used to extrapolate to potential effects on a variety of species (receptors) 

included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature will be used to evaluate the potential direct and indirect effects of 

fenbutatin-oxide to aquatic and terrestrial receptors. 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 identified through EPA’s ECOTOXicology (ECOTOX) 

database (USEPA 2009a), which employs a literature search engine for locating chemical 

toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of 

data may also provide insight into the direct and indirect effects 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 ECOTOX 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 and 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 toxicity classifications. 

A summary of the aquatic and terrestrial toxicity data is provided in Sections 4.1 and 4.2, 

respectively. In addition, a summary of ecological incidents associated with fenbutatin-oxide and 

a description of ecosystems potentially at risk are provided in Sections 4.3 and 4.4, respectively. 
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Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of Fenbutatin-oxide and the 

Associated Acute Toxicity Classification. 

Taxonomic 

Group Surrogate Species Acute and Chronic Toxicity Endpoints* 

Citation 

MRID 

Acute Toxicity 

Classification 

Bobwhite quail 

(Colinus 

virginianus) 

Acute oral LD50 >2,510 mg a.i./kgbw 00113073 Practically non-toxic 

Mallard duck 

(Anas 

platyrhynchos) and 

Bobwhite quail 

Sub-acute 8-day LC50>5,620 mg 

a.i./kg diet 00113074 

40473505 Practically non-toxic 

Birds1

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 LD50 = 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 

F2 litters) 

41540601 -- 

Acute contact 48-hr LD50 = 3,982 μg 

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./A2 00088398 -- 

Acute 96-hr LC50=1.7 μg a.i./L (static; 

nominal concentrations) 00113075 Very highly toxic 

Freshwater fish3

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 reduced 

larval survival and growth) (flowthrough, measured concentrations) 

40473512 -- 

Acute 48-hr EC50 = 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 LC50= 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 LC50= 2.8 μg a.i./L 

(static; measured concentrations) 40590508 Very highly toxic 

Eastern oyster 

(Crassostrea 

virginica) 

Acute 48-hr EC50= 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 toxicity 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 toxicity endpoints for freshwater invertebrates and 

estuarine/marine fish exceed the solubility limit of fenbutatin-oxide (12.7 μg a.i./L); however, a 

solvent (i.e., acetone) was used to enhance the 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 conducted under static conditions and only nominal test 

concentrations were available. It should be noted that study classifications 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 solubility and tendency for fenbutatin-oxide to sorb, 

measured test concentrations are required in freshwater acute studies to provide reliable exposure 

concentrations and measurement endpoints. 
13 of 43

Chronic exposure to fenbutatin-oxide resulted in a reduction in larval survival and growth in 

freshwater fish and a reduction in growth and percent of adult survival, and decreased 

reproduction (reduced total number of young) in freshwater invertebrates. Chronic toxicity data 

are not available for estuarine/marine fish and invertebrates; therefore, an acute-to-chronic ratio 

is used to estimate chronic endpoints based on freshwater fish and invertebrate data. Based on 

the freshwater fish data for rainbow trout, the resulting estimated NOAEC for estuarine/marine 

fish is 3.80 μg a.i./L (freshwater fish LC50 of 1.7 μg a.i./L / freshwater fish NOAEC of 0.31 μg 

a.i./L = 5.48; estuarine/marine fish LC50 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 EC50 of 31 μg a.i./L / freshwater 

invertebrate NOAEC of 16 μg a.i./L = 1.94; estuarine/marine invertebrate EC50 = 0.37 μg a.i./L / 

1.94 = 0.19 μg a.i./L. However, given that fenbutatin-oxide is less toxic to freshwater 

invertebrates than estuarine/marine invertebrates, 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 toxicity to freshwater and estuarine/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 birds, mammals, and honey bees on an 

acute exposure basis. For birds, chronic exposure resulted in decreased reproduction (reduction 

in the number of eggs laid); for mammals, chronic exposure resulted in decreased growth 

(reduction in body weight, food consumption, and pup weight during lactation). No fenbutatinoxide data are available for terrestrial plants. Terrestrial plant toxicity 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-oxide assessments, no degradates of concern have 

been identified. The Health Effects Division’s (HED) Metabolism Assessment Review 

Committee (MARC) met on March 20, 2001 to consider the degradation of fenbutatin-oxide in 

water. Specifically, MARC was asked to determine 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 water risk assessment. Although MARC expressed 

concern about the toxicity of other metabolites 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 very low levels, if at all. The Committee based its decision on the 

following: (1) in laboratory and field studies, the degradates were found only at trace levels or 

not at all; and (2) based on the fate and transport 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. 
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4.4. Incident Database Review 

The Agency maintains an incident database system (Ecological Incident Information System or 

EIIS) to track and evaluate accidental kills associated with pesticide use. The likelihood that a 

particular pesticide caused the incident 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 total of two incidents associated with fenbutatin-oxide use have 

been reported (both involving terrestrial 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 Washington, DC, involving a dwarf Alberta pine tree 

(incident no.: I009262-105). The certainty in which these incidents 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 mixture including chlorpryrifos (Lorsban® 4E), spinosad 

(Success®), and fenbuatain-oxide (Vendex®) (at registered application 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 field; however, no terrestrial 

plant toxicity data are available for this chemical. 

Incident I009262-105 (Dwarf Alberta 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 active 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 was 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 scope; 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 ecosystems potentially at risk could include the treated 

field and areas immediately adjacent to the treated field that may receive drift or runoff. Areas 
15 of 43

adjacent to the treated field could include cultivated fields, fencerows and hedgerows, meadows, 

fallow fields or grasslands, woodlands, riparian habitats and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to, or down stream from, the 

treated field and might include impounded bodies such as ponds, lakes 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 actual environmental value that is to be protected, as defined 

by an ecological entity (species, community, or other entity) and its attribute or characteristics 

(USEPA 1998). For fenbutatin-oxide, the ecological entities include the following: birds, 

reptiles, terrestrial-phase amphibians, mammals, freshwater fish, freshwater aquatic-phase 

amphibians and invertebrates, estuarine/marine fish and invertebrates, terrestrial plants, 

terrestrial invertebrates, and aquatic plants. The attributes for each of these entities include 

growth, reproduction, and survival. 

6. Conceptual Model 

For a pesticide to pose an ecological risk, it must 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 receptor. 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, and a feasible route of exposure. 

The conceptual model for fenbutatin-oxide provides a written description and visual 

representation of the predicted relationships between fenbutatin-oxide, potential routes of 

exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of 

two major components: risk hypothesis and a conceptual diagram (USEPA 1998).

6.1. Risk Hypothesis 

A risk hypothesis describes the predicted relationship among the stressor, exposure, and 

assessment endpoint response along with the rationale for their selection. For fenbutatin-oxide, 

the following ecological risk hypothesis is being employed for this national-level ecological risk 

assessment: 

Based on the application methods, mode of action, direct toxicity to non-target aquatic 

and terrestrial species, and potential indirect effects to trophic food webs, the use of 

fenbutatin-oxide has the potential to reduce survival, reproduction, and/or growth in 

terrestrial and aquatic animals and plants through direct application, spray drift, and 

runoff of sediment-bound residues (erosion). These non-target organisms include 

Federally-listed threatened and endangered species as well as non-listed species. 
16 of 43

In order for a chemical to pose an ecological risk, it must reach non-target organisms at 

concentrations found to cause adverse effects. The assessment of ecological exposure pathways 

will include an examination of the source and potential migration pathways to fenbutatin-oxide 

exposure, and the determination of potential adverse effects on non-target species. 

6.2. Conceptual Diagram 

Application methods for fenbutatin-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 applications are not precluded on the labels, 

both ground and aerial applications will be assessed. Ecological receptors that may potentially 

be exposed to fenbutatin-oxide include terrestrial and semi-aquatic wildlife (i.e., mammals, birds, 

terrestrial-phase amphibians, terrestrial invertebrates, and reptiles) and plants. In addition, 

aquatic receptors (e.g., freshwater and estuarine/marine fish and invertebrates, aquatic-phase 

amphibians, and plants) may also be exposed as a result of potential movement of fenbutatinoxide via spray drift and/or runoff 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) and terrestrial (soil and foliage) 

habitats. The movement away from the site of application in turn represents exposure pathways 

for a broad range of biological receptors of concern (non-target animals and plants) and the 

potential attribute changes, i.e., effects such as reduced survival, 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, ingestion through preening activities, or uptake through 

inhalation or dermal absorption by terrestrial animals. Exposure to terrestrial animals is based 

primarily on dietary consumption of foliar residues while aquatic assessments assume that all 

major potential routes of direct exposure are accounted. Given the low solubility of fenbutatinoxide and its propensity to partition to sediments, the chemical is not expected to leach in 

groundwater. Also, given the low volatility of fenbutatin-oxide coupled with its short 

atmospheric half-life, the compound is not expected to move via atmospheric transport. As such, 

neither groundwater nor atmospheric 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 effects 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 fenbutatin-oxide effects on terrestrial organisms. 

7. Analysis Plan 

In order to address the risk hypothesis, 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 effects concentration) approach. Although risk is often defined as 

the likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does 

not provide a quantitative estimate of likelihood and/or magnitude of an adverse effect. 

However, as outlined in the Overview Document (USEPA 2004), the likelihood of effects to 

individual organisms from particular uses of fenbutatin-oxide is estimated using the probit doseresponse slope and either the level of concern (discussed below) or the actual calculated risk 

quotient value. 

This analysis plan will be revisited and may be revised depending upon the data available in the 

open literature and the information submitted by the public in response to the opening of the 

Registration Review docket 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-phenylpropyl stannonic acid (SD 33608), have been 

identified in the field dissipation studies. On a structural basis, these degradates are not similar 

to the parent (Appendix A) and based on the results of previous 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 based 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 contaminants, and the differential effects of other 

physical/chemical characteristics of the receiving waters (e.g. organic matter present in sediment 

and suspended water). Evaluation of factors that 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 could over- or under-estimate risks 

depending on the type of interaction and factors discussed above. 

7.2. Measures of Exposure 

In order to estimate risks of fenbutatin-oxide exposures in aquatic and terrestrial environments, 

all exposure modeling and resulting risk conclusions will be based on maximum application rates 

and methods cited in 

Table 1 and will be estimated for each use of fenbutatin-oxide. Measures of exposure are based 

on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of 

fenbutatin-oxide. The models used to predict aquatic EECs are the Pesticide Root Zone Model 

coupled with the Exposure Analysis Model System (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. These models are parameterized using relevant 

reviewed environmental fate data from registrant submissions and the literature; model input 

values will be consistent with the most recent version of the input parameter 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 models generate daily exposures and calculated 1-

in-10 year EECs of fenbutatin-oxide that may occur in surface water bodies adjacent to 

application sites receiving fenbutatin-oxide through runoff and spray drift. PRZM simulates 

pesticide application, movement, and transformation on an agricultural field and the resultant 

pesticide loadings to a receiving 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 

m3 volume) with no outlet. PRZM/EXAMS is used to estimate screening-level exposure of 

aquatic organisms to fenbutatin-oxide. The measure of exposure for aquatic 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-phase amphibians. The 1-in-10-year 21-day mean 

is used for assessing chronic exposure 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 animals 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 nomograph, 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 95th

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, including information on 118 species of plants, 121 

pesticides, and 17 chemical classes. EECs for terrestrial plants inhabiting dry and wetland areas 

are derived using TerrPlant (version 1.2.2, 12/26/2006). This model uses estimates of pesticides 

in runoff and in spray drift to calculate EECs. EECs are based upon solubility, application rate 

and minimum incorporation depth. 

The KABAM model (KOW (based) Aquatic BioAccumulation Model; version 1.0; 4/7/09) is 

used to estimate potential bioaccumulation of fenbutatin-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 risk 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 

KOW to estimate uptake and elimination constants through respiration and diet of organisms in 

different trophic levels of the aquatic community. 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 levels, including: phytoplankton, zooplankton, benthic 

invertebrates, filter feeders, small juvenile fish, medium sized fish, and larger upper-trophic level 

fish. 

Two spray drift models, AGDisp and AgDRIFT are used to assess exposures of terrestrial plants 

to fenbutatin-oxide deposited in terrestrial habitats by spray drift. AGDisp (version 8.13; dated 

12/14/2004) is used to simulate aerial and ground applications. AgDrift (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 direct 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 mixture toxicity data for aquatic life, terrestrial 

plants, and wildlife. ECOTOX was 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 animals is also collected 

from the Ecological Incident Information System (EIIS; USEPA 2009b). The EIIS is a database 

containing adverse effect (typically mortality) reports on non-target organisms where such 

effects have been associated with the use of pesticides. Incidents reported in the aggregate 

incident reports and the Avian Incident Monitoring System (AIMS) will also be searched. AIMS 

is a database administered by the American Bird Conservancy (it was partially funded by the 

EPA). It contains publicly available data on reported avian incidents involving pesticides 

(http://www.abcbirds.org/abcprograms/policy/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 coloration). Quantitative assessments of risks, though, are limited to 

those endpoints that can be directly 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 birds is similar to terrestrial-phase amphibians and reptiles. The 

same assumption is made for fish and aquatic-phase amphibians. 

The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50. 

LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at once, that is 

estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” 

and LC50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. 

EC stands for “Effective Concentration” and the EC50 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-listed animals are the NOAEL/NOAEC and NOEC. 

NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest tested dose of 

a substance that has been reported to have no harmful (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 from the control. The NOEC is 

the No-Observed-Effects-Concentration. For non-listed plants, only acute exposures are 

assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed plants, either the 

NOAEC or EC05 is used. 
22 of 43

7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure 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 effects to non-target organisms in 

aquatic and terrestrial habitats. The exposure and toxicity effects data 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 divided by acute and chronic toxicity values. The resulting RQs are 

then compared to the Agency’s Levels of Concern (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/scipoly/sap/index.htm) and have been 

deemed as appropriate means of refining assessments 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 threatened and/or endangered (listed) species from 

registered uses of fenbutatin-oxide. This assessment will be conducted in accordance with the 

Overview Document (USEPA 2004), provisions 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 indirectly affected by the 

federal action, as indicated by the exceedance of Agency Levels of Concern (LOCs) used to 

evaluate direct or indirect effects. The Agency’s approach 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 exceeds the Agency’s LOCs. Specific measures of 

ecological effect that define the action area for listed species include any direct and indirect 

effects and/or potential modification of its critical habitat, including reduction in survival, 

growth, and reproduction as well as the full suite of sublethal effects available in the effects 

literature. Therefore, the action area extends to a point where environmental exposures are 

below any measured lethal or sublethal effect threshold for any biological entity at the whole 

organism, organ, tissue, and cellular level of organization. In situations 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 was conducted in 2001 in support of the fenbutatinoxide TRED. However, the estimates were derived 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 drinking water assessment will incorporate model 

estimates of fenbutatin-oxide in surface and ground waters. Concentrations of fenbutatin-oxide 

in surface waters will be estimated using PRZM/EXAMS (see description above). Ground water 

estimates of fenbutatin-oxide concentrations will be established 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 terrestrial, food and non-food uses and greenhouse 

uses. According to Code of Federal Regulations 40 (CFR40 2007) Part 158 Subpart D (data 

requirements for pesticides) environmental fate and non-target organism effect data are required 

for fenbutatin-oxide based on its terrestrial use. Available studies submitted to fulfill 

environmental fate and ecological effects guideline requirements, as well as outstanding data 

gaps for fenbutatin-oxide, are defined in Table 4-7, below. 

Further information on data required to fulfill the Agency’s guideline requirements for 

fenbutatin-oxide and its formulated products is presented as the Data Call-in (DCI) table in 

Appendix B. In addition to providing the guideline number 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 could impact the Agency’s future decision-making. 

7.8.1. Fate 

The environmental fate data requirements for fenbutatin-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. The data gap for the bioaccumulation data is 

discussed below. 

Table 4. Available environmental 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 Field 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 accumulated in bluegill 

sunfish (Lepomis macrochirus); however, the accumulation of fenbutatin-oxide in the various 

tissue fractions did not reach a plateau (equilibrium) 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 alter our understanding of potential exposure through 

the aquatic food chain. 

7.8.3. Effects 

 

Although many submissions have been made to provide 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 the following: avian acute oral toxicity testing, 

chronic toxicity studies with estuarine/marine fish and invertebrates, sediment toxicity studies 

with freshwater and estuarine/marine invertebrates, and Tier I aquatic and terrestrial plant 

studies. In addition, acute toxicity studies with measured test concentrations are required for 

freshwater fish and invertebrates. 

 

Table 5. Available ecological effects data for terrestrial 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 

850.2300 Avian reproduction 41258901 Acceptable No 

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 

Yes1 

850.1075 Saltwater fish – 

Acute toxicity 41483301 Acceptable No 

850.1010 

Freshwater 

invertebrates – 

Acute toxicity 

40473509 Supplemental Yes2 

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 Yes3

850.1400 Freshwater fish – 

early life stage test 40473512 Supplemental No 

850.1400 Saltwater fish – 

early life stage test 

None NA Yes4

850.1735 

Whole sediment 

toxicity invertebrates, 

freshwater 

None NA Yes5 

850.1740 

Whole sediment 

toxicity invertebrates, 

marine 

None NA Yes6

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 to 

sediment 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 effects data for plants exposed to fenbutatin-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 are required for all 

terrestrial food and non-food use 

patterns. 

NA = not available 

Avian Acute Oral Toxicity 

Acceptable acute avian oral toxicity data 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 requirements for conventional pesticides (72 FR 

60934; USEPA 2007). The Part 158 data requirements specify that acute avian oral toxicity data 

be submitted for either a mallard duck (Anas platyrhynchos) or bobwhite quail AND a passerine 

species. Therefore, an avian acute 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 data are not submitted for passerines, EFED will assume acute risk 

for passerine species. 

Acute Toxicity Studies with Freshwater 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 associated measurement endpoints. Endpoints that 

are based on nominal concentrations may underestimate the toxicity of fenbutatin-oxide due to 

its low solubility and propensity to sorb to the glass surfaces of test containers. Therefore, an 

acute freshwater fish study with rainbow trout (Oncorhyncus mykiss) (OPPTS Guideline 

850.1075) and an acute freshwater invertebrate study with the water flea (Daphnia magna) 

(OPPT Guideline 1010) are required in order to address uncertainties associated with endpoints 

that are based on data from static tests and nominal test concentrations. Both freshwater acute 

studies must be conducted under flow-through conditions and measured test concentrations must 

be provided. 

Chronic Toxicity Studies with Estuarine and Marine Fish and Invertebrates 

Chronic toxicity data are not available for estuarine and marine fish and invertebrates. 

According the Part 158 data requirements, chronic data are required for estuarine fish and 

invertebrates if the acute LC50 value is < 1,000 μg/L. Given that the acute estuarine/marine fish 

and mysid (Americamysis bahia) LC50 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 invertebrates tested; the 

reason(s) for the difference in toxicity is unclear. Because no toxicity data for chronic exposures 

are available for estuarine/marine invertebrates and 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 invertebrates from chronic exposures to fenbutatin-oxide. 

Therefore a chronic mysid full life-cycle 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 for estuarine/marine fish and invertebrates, EFED will assume 

chronic risk to estuarine/marine fish and invertebrates. 

Sediment Toxicity to Freshwater and Estuarine/Marine Benthic Invertebrates 

Based on the persistence in and partitioning of fenbutatin-oxide to sediments, this pesticide has a 

propensity to sorb to particles and move to adjacent surface water through runoff of sedimentbound residues (erosion) following high rain events. According to the Part 158 data 

requirements, chronic freshwater sediment toxicity 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 (Kd) is > 50. 

• The log KOW is > 3. 

• The KOC is > 1,000. 

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

Kd values range from 1,282 to 2,333 L/kg, and the log KOW is 5.14; therefore, the requirements 

for chronic freshwater sediment toxicity testing are met. Sediment toxicity testing is required 

with estuarine/marine invertebrates if environmental concentrations 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 available acute toxicity data. 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 finding tests) should be completed with 

fenbutatin-oxide per OPPTS Guidelines 850.1735 and 850.1740 for sediment dwelling 

freshwater and estuarine/marine invertebrates, respectively. Measured concentrations of the test 

substance in the sediment, pore water, and overlying 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 terrestrial plants are not available. 

Based on the 40 CFR Part 158 data requirements, Tier I level non-target aquatic and terrestrial 

plant data are required for all insecticides. In addition, available incident data for fenbutatinoxide shows two incident reports for plants, and potential phytotoxic effects associated with 
28 of 43

fenbutatin-oxide are noted on the end-use product labels. Therefore, 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 fenbutatin-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 instrument 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 cyanobacterial 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 Assessment Process in the Office of Pesticide Programs. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of 

Pesticide Programs, Washington DC. January 23, 2004. 

USEPA. 2007. 40 CFR Part 158. Pesticides; Data Requirements 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 Marine 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 119Sn-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 119Sn-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 119mSn-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 119Sn-SD-14114: Shell Re- port No. TIR-22-002-80. Unpublished study 

prepared by Shell Development Co. 30 p. 

MRID: 40257002 

Lee, P. (1980) Anaerobic Soil Metabolism of 119Sn-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) Field 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: Adsorption/ 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.; Wetherington, J. (1993) Field Soil Dissipation of Vendex Miticide: 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 Bioconcentration 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 International, 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. (Unpublished study received Apr 2, 1979 under 201-369; prepared by Wildlife International, 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 Acute 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 dated Aug 15, 1973 ?Test conditions of SD 14114|. (U.S. 

Environmental Protection Agency, Gulf Breeze Environmental Research Laboratory; unpublished study; 

CDL:093941-P). 

MRID: 113077 

Sanborn, J.; Nugent, K.; Reeves, G.; et al. (1979) A Study 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. Protection 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. (1979) Rat Acute Oral Toxicity: Project No. 1367-79. 

(Unpublished study received Jan 10, 1980 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 Metabolite SD 31723: TLGR.0037.73. (Unpub- lished study received on unknown 

date under 4F1492; prepared by Shell 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 submission received Jun 25, 1974 under 4F1492; submitted by Shell Chemical 

Co., Washington, DC; CDL:094519-K). 

MRID: 113038 

Samuels, G. (1972) Toxicity Test 1: ?Mouse|. (Unpublished study received Jun 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 Sittingbourne 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 Rats with TD2336-1: Lab Project 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 43

Appendix A. Fenbutatin-oxide and Degradates Chemical (CAS Number) MW Structure SMILES Fenbutatin-oxide (13356-08-6) 

1052.67 [Sn](CC(C)(C)c1ccccc1)(CC(C)(C)

[Sn](CC(C)(C)c4ccccc4)(CC(C)(C)

1,3-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)

2-methyl-2-phenylpropyl stannonic 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 registration 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 concentrations to which fish and invertebrates may be 

exposed, aerobic aquatic metabolism 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 decision 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 registration 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 reliably 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 will identify any transformation products that may 

occur. 

How could the data change the Agency’s decision 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 accumulation of fenbutatin-oxide in the various 

tissue fractions did not plateau (equilibrate) during 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 Kow 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 decision or impact the Agency’s future decisionmaking? 

If data indicate that fenbutatin-oxide accumulates 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 were submitted for exposures of bobwhite quail to 

fenbutatin-oxide; however, data are not available for a passerine species, which are now required 

under the 40 CFR Part 158 (CFR 40 2007) data requirements for conventional pesticides. The Part 

158 data requirements specify that acute avian oral toxicity data be submitted 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/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Guidelines/Drafts/850-

2100.pdf ). A passerine study protocol must be submitted 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 species will be used to refine the screening-level 

assessment by determining whether there are differences 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 birds 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 data have been submitted for fenbutatin-oxide, the 

available data are based on static studies where only 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 solubility 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_Harmonized/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, and 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. 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: 850.1350 

Study Title: Mysid Chronic Toxicity Test 

Rationale for Requiring the Data 

An acceptable chronic full life-cycle estuarine/marine invertebrate 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 LC50 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 determining whether chronic exposure to fenbutatin-oxide 

may potentially impact the life-cycle of estuarine/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 the study will be used to address the uncertainty 

regarding the potential for enhanced sensitivity of estuarine/marine invertebrates 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 decision or impact the Agency’s future decisionmaking? 

If the data indicate that fenbutatin-oxide poses a significant chronic risk to invertebrates inhabiting 

estuarine/marine water bodies, the Agency may explore additional options to minimize the risk of 

fenbutatin-oxide to estuarine/marine invertebrates. If future endangered species 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 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: 850.1400 

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 LC50 value is <1 mg/L. The early life-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 determining 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 would allow the Agency to refine its screening-level 

risk assessment by considering chronic exposure and potential toxicity and risk to estuarine/marine 

fish. In addition, these data would allow the Agency 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 reduction 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 explore 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 indirectly). 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 registrants 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 Testing with Freshwater and Marine Invertebrates 

Rationale for Requiring the Data 

Fenbutatin-oxide has a propensity to sorb to sediment 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 KOW, and Kd 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 60934; 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 finding tests) should be completed with fenbutatinoxide per OPPTS Guidelines 850.1735 and 850.1740 

(http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/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 test 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 the Agency to reduce uncertainties associated with 

the potential for enhanced exposure to fenbutatin-oxide that is sorbed to sediment and subsequent 

risk to freshwater and estuarine/marine benthic invertebrates. 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, the Agency may explore additional decision options 

to minimize the risk of fenbutatin-oxide to freshwater 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 affect” 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 level non-target aquatic plant data are required for 

all insecticides. Therefore, non-target aquatic plant data for algae and vascular plants per OPPTS 

Guidelines 850.4400 and 850.5400 

(http://www.epa.gov/opptsfrs/publications/OPPTS_Harmonized/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 will be used to estimate potential risks to aquatic 

vascular and non-vascular plants associated with the use of fenbutatin-oxide. The data will reduce 

uncertainties associated with the current risk assessment for aquatic plants and will improve the 

Agency’s understanding of the potential effects of fenbutatin-oxide on aquatic plants. In the absence 

of Tier I data, risks for both vascular and non-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 overall water quality, a solid understanding of the 

potential risks to aquatic plants is essential for sound environmental risk management decisionmaking. Without aquatic plant data for fenbutatin-oxide, 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 habitat), 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 emergence and vegetative vigor toxicity (Tier I) 

Rationale for Requiring the Data 

Fenbutatin-oxide toxicity data for terrestrial plants are not available. Based on the 40 CFR Part 158 

data requirements, Tier I level non-target terrestrial plant data are required for insecticide end-use 

products at the maximum application rate. In addition, 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 labels. 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_Harmonized/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 emergence 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 associated with the current risk assessment for terrestrial and semiaquatic plants and will improve the Agency’s understanding of the potential effects of fenbutatinoxide on terrestrial and semi-aquatic plants. In the 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 listed species, an understanding of the potential risks to 

terrestrial and semi-aquatic plants is essential for 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 result 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 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. 
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