- Page 2 of 102

-



### invertebrates ( i.e. insects), and freshwater and estuarine/marine invertebrates. Table 1 summarizes the representative uses assessed and the taxa that may potentially be directly at risk from exposure to dicrotophos

.

Summary

Dicrotophos is used on cotton with a maximum application rate of 0.5 lb a.i./ac and as a tree injection with maximum application rate contingent upon tree diameter. Dicrotophos is stable to photolysis, persistent to hydrolysis and metabolizes readily in a erobic and anaerobic environments. It is also mobile and does not bioaccumulate. Dicrotophos is very highly toxic to mammals, birds, and aquatic invertebrates on an acute basis; highly toxic to honey bees on an acute basis; slightly to moderately acutely toxic to fish; and minimally toxic to terrestrial and aquatic plants

. In terms of its chronic toxicity profile, chronic risks exceeding established levels of concern are identified for birds, mammals, and aquatic invertebrates for dicrotophos used on

cot ton.

Basic Uncertainties

The tree injection use pattern (EPA Reg. No. 7946

- 11) does not limit the number of applications that can be made in a given year or season. Further, the stated application rate is based on number of capsules for a given tree s ize. The number of capsules applied is the diameter of the tree at breast height, in inches, divided by two. However, the size of the capsule can be variable according to the label which would result in substantially different applications depending on

c apsule size (one to three milliliters)

. Given these uncertainties, maximum single application and maximum annual application cannot be precisely determined.

The fate of dicrotophos when injected into the tree is a considerable uncertainty. The suite of chemical fate data EFED receives has little bearing on how a chemical behaves when injected into a tree. The rates of degradation in the tree, mobility to various parts of the tree, and formation of degradates cannot be characterized by current data. Fu rther, t he dispersion of dicrotophos

- treated trees across various landscapes is a spatial uncertainty.

The understanding of dicrotophos half

- lives in aerobic soil and aquatic metabolism are based

upon on a single study testing only a single soil. The 2.7 day half

- life is multiplied by an uncertainity factor (3X) to derive the model parameters but it must still be considered that one soil is being used to represent thousands of soils and microbial communities with variable types

and rates of metabolism in addition to many aquatic environments with similar variability.

The occurrence of monocrotophos , a metabolite of dicrotophos found in a cotton foliar residue study, in and/or on plant tissue is a considerable uncertainty in this assessmen t. Monocrotophos is known to be more toxic to avian species than dicrotophos on an acute basis, and while residues of monocrotophos on foliage are presumed to be lesser (on a mass per unit volume or mass per unit area basis), the enhanced toxicity of this compound may effectively extend the time of acute risk LOC exceedances following dicrotophos application.- Page 3 of 102

-



### The available avian acute and subacute studies are not robust. Many of the available studies lack a sufficient number of treatment levels; t reatm ent level spacing is also problematic . For most studies, uncertainties would be reduced if additional study conduct details were available. Specifically, the percent active ingredient of the test material for the most sensitive acute oral

and sub

- acute d ietary test species is a considerable uncertainty. The avian RQs reported in this assessment may underestimate toxicity since the compound purity was presumed to be technical grade.

An acceptable foliar residue toxicity study with honey bees (OCSPP 850 .3030) would allow for

determination of a 24

- h RT 25 

### . This data would reduce uncertainties surrounding the length of time post

- application that residues of dicrotophos on foliage are toxic to honey bees.

### Page 4 of 102

Table 1. Risk Resulting from D icrotophos Exposure Presented by Taxon

Use Pattern Aquatic

Invertebrates Fish (surrogate

for aquatic

- phase amphibians) Birds,

(surrogate for reptiles and

terrestrial

- phase amphibians) Mammals Plants Terrestrial

Invertebrates

Cotton Acute risk:

Yes 1

Chronic risk : Yes 1 Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Yes 1

Chronic risk : Yes 1 Acute risk :

Yes 1

Chronic risk : Yes 1 Terrestrial:

Not expected

Aquatic: Not expected Acute risk :

Yes 1

Tree injection Acute risk : Uncertain 2

Chronic risk : Uncertain 2 Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Uncertain 2

Chronic risk : Uncertain 2 Acute risk :

Uncertain 2

Chronic risk : Uncertain 2 Terrestrial:

Not expected

Aquatic: Not expected Acute risk :

Uncertain 2

1 “ Yes ” indicates risk concerns for both listed and non

- listed taxa

2 Risk is u ncertain in the absence of data describing the dispersion of treated trees and magnitude of residues in tree tissue and exudate

### Page 5 of 102

Additional Considerations for Listed Species



### Based on this screening

- level assessment, there are potential risks of direct effects to listed and

non

- listed freshwater and estuarine/marine invertebrates, mammals, birds (birds are surrogates for terrestrial phase reptiles and amphibians), and terrestrial invertebrates from the use of dicrotophos on cotton . Listed species of freshwater and estuar ine/marine invertebrates, mammals, birds, and terrestrial invertebrates may also be affected through indirect effects because of the potential direct effects on listed and non

- listed species. Potential direct effects on

listed and non

- listed freshwater an d estuarine/marine invertebrates (cotton use pattern only), mammals, birds, and terrestrial invertebrates from the use of dicrotophos may be associated with

modification of P rimary C onstituent E lements (PCEs) of designated critical habitats, where such

des ignations have been made. However, a t this current stage of the Registration Review process, it is premature to make effects determinations for listed species until further scientific analysis

and refinements are conducted , based on recommendations receiv ed from the National Academy of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at http://www.nap.edu/catalog.php?record_id=18344 . The NAS report outlines recommen dations on specific scientific and technical issues related to the development of pesticide risk assessments that are compliant with the Endangered Species Act (ESA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

The EPA along with t he U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA), released a summary of their implementation plan for assessing risks of pesticides to listed s pecies ahead of the stakeholder workshop held on November 15, 2013. This plan was developed in response to the NAS’ recommendations, including a common approach to risk assessment as a way of addressing scientific differences between EPA and the Services. During the workshop, the agencies received feedback from the public on the interim scientific approaches that were developed as part of the initial implementation of the NAS recommendations. These approaches will be jointly implemented and vetted as par t of a phased iterative process. Once fully vetted, EPA will further refine the listed species effects determination portion of this risk assessment.

To make effects determinations for individual listed species, useful refinements may include, but

are not limited to, analyses of: 1) more detailed, species

- specific ecological and biological data; 2) more detailed and accurate information on dicrotophos use patterns; and 3) sub

- county level spatial proximity data for the co

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

EFED is currently developing tools th at are expected to further refine the assessment and are designed to support effects determinations for individual federally listed species and their designated critical habitats (where applicable). Scientific information obtained from the

Services , and o ther reliable sources is being collated by EFED to address all currently listed species. Th is information is be ing stored in an Office of Pesticide Programs (OPP) P esticide

R egistration I nformation S yste M (PRISM) listed species knowledgebase. The listed species knowledgebase consist s of an information repository that houses biological and behavioral information relevant to individual species ( e.g. , habitat, diet, and life history, including specific temporal and spatial associations) and a document reposi tory that contains supporting documents ( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial- Page 6 of 102

-



### taxa, biological information relevant to the assessment ( e.g ., diet and body weight) will be used to parameterize expos ure estimates using a method consistent with currently used methods in the

T

- REX and T

- HERPS models.

Refinements will also include more detailed analyses of the registered uses and specific use patterns that result in either “Likely to Adversely Affect” (LAA) or “Not Likely to Adversely Affect” (NLAA) determinations for federally listed species. The analyses may include more information on where, when, and how dicrotophos is used on all use sites

. Actual usage data (when available) and national land

- co ver datasets that indicate potential use sites [ e.g ., N ational

L and C over D ataset (NLCD), C rop land D ata L ayer (CDL)] may be used to support a more refined analysis of where dicrotophos is reasonably expected to be used. Similarly, refinements

on the timin g of applications and a more in

- depth exploration of agronomic practices for dicrotophos may be included as part of the refinement.

The refinements based on individual species data; additional, detailed usage information, when available; and recommendatio ns from the NRC report are expected to help to more accurately identify potential areas of effect and to better inform effects and habitat determinations for listed species and any designated critical habitats.- Page 7 of 102

-



# Environmental Fate and Ecological Risk Assessment for the Registration of Dicrotophos

Dicrotophos [(E)

- 4

- dimethylamino

- 4

- oxobut

- 2

- en

- 2

- yl] dimethyl phosphate

CAS Registry Number 0000141

- 66

- 2

PC Code 035201

Prepared by:
Andrew Shelby, Physical Scientist Nathan Miller, Biologist
U. S. Environmental Protection Agency Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V I 1200 Pennsylvania Ave., NW

Mail Code 7507P Washington DC 20460 Reviewed by:

Brian Kiernan

, Biologist

, ERB V I
William P. Eckel, Ph.D, Senior Science Advisor, ERB VI
Mark Corbin, Branch Chief, ERB VI



### July 10 , 2014- Page 8 of 102

-



## Table of Contents

1. Executive Summary

................................ ................................ ................................ ............ 10

2. Problem Formulation

................................ ................................ ................................ ......... 12

2.1. N ature of Regulatory Action

................................ ................................ ................................ .................. 12

2.2. Stressor Source and Distribution

................................ ................................ ................................ .......... 12

2.2.1. Nature of Chemical Stressor

................................ ................................ ................................ .............. 12

2.2.2. Overview of Pesticide Usage

................................ ................................ ................................ ............. 13

2.3. Receptors

................................ ................................ ................................ ................................ ................. 13

2.3.1. Aquatic and Terrestrial Effects

................................ ................................ ................................ .......... 13

2.3.2. Ecosystems Potentially at Risk

................................ ................................ ................................ .......... 14

2.4. Assessment Endpoints

................................ ................................ ................................ ............................ 14 2.5. Conceptual Model

................................ ................................ ................................ ................................ ... 14

2.5.1. Risk Hypotheses

................................ ................................ ................................ ................................ 15

2.5.2. Conceptual Diagram

................................ ................................ ................................ .......................... 15 2.6. Analysis Plan

................................ ................................ ................................ ................................ ........... 17

2.6.1. Residues of Concern

................................ ................................ ................................ .......................... 17

2.6.2. Preliminary Identification of Data Gaps and Uncertainties

................................ ............................... 17

2.6.3. Evaluation of Multiple Active Ingredients, Mixtures and Formulated Products

............................... 18

2.6.4. Measures of Exposure

................................ ................................ ................................ ....................... 18

2.6.5. Measures of Effect

................................ ................................ ................................ ............................. 20

2.6.6. Integration of Exposure and Effects

................................ ................................ ................................ .. 21 

### 3. Analysis

................................ ................................ ................................ ............................. 22

3.1. Use Characterization

................................ ................................ ................................ .............................. 22

3.2. Exposure Characterization

................................ ................................ ................................ .................... 23

3.2.1. Environmental Fate and Transport Characterization

................................ ................................ ......... 23 N,N

- dimethyl

- 3

- oxobutanamide

................................ ................................ ................................ .......................... 28 {[1

- (dimethylcarbamoyl)propan

- 2

- yl]oxy}(methoxy)phosphinic acid

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

3

- hydroxy

- N,N

- dimethylbutanamide

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

3

- [(dimethoxyphosphoryl)oxy]

- N

- methylbut

- 2

- enamide

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

3.2.2. Measures of Aquatic Exposure

................................ ................................ ................................ .......... 29

3.2.3. Measures of Terrestrial Exposure

................................ ................................ ................................ ...... 33

3.3. Ecological Effects Characterization

................................ ................................ ................................ ...... 35

3.3.1. Aquatic Toxicity Assessment

................................ ................................ ................................ ............ 36

3.3.2 Terrestrial Effects Characterization

................................ ................................ ................................ ... 40


### 4. Risk Characterization

................................ ................................ ................................ ......... 45

4.1. Risk Estimation

................................ ................................ ................................ ................................ ....... 45

4.1.1. Aquatic Organisms

................................ ................................ ................................ ............................ 46

4.1.2. Terrestrial Organisms

................................ ................................ ................................ ........................ 48

4.2. Incident Database Review

................................ ................................ ................................ ............................ 53

4.3. Risk Description

................................ ................................ ................................ ................................ ...... 55

4.3.1 Exposure to Aquatic Organisms

................................ ................................ ................................ ........ 55

4.3.1.1. Risks to Aquatic Animals

................................ ................................ ................................ .................. 56

4.3.1.2. Risks to Aquatic Plants

................................ ................................ ................................ ...................... 56

4.3.2. Exposure to Terrestrial Organisms

................................ ................................ ................................ .... 56

4.3.2.1. Risks to Mammals

................................ ................................ ................................ ............................. 56

4.3.2.2. Risk to Birds

................................ ................................ ................................ ................................ ...... 60

4.3.2.3. Risk to Terrestrial Invertebrates

................................ ................................ ................................ ........ 63

4.3.2.4. Risk to Terrestrial Non

- target Plants

................................ ................................ ................................ . 64

4.4. Uncertainties and Data Gaps

................................ ................................ ................................ ................. 65

4.4.1. Fate and Transport

................................ ................................ ................................ ............................. 65

4. 4.2. Effects

................................ ................................ ................................ ................................ ................ 65


### 5. Endocrine Disruptor Screening Program (EDSP)

................................ ........................... 66- Page 9 of 102

-



### 6. Federally Threatened and Endangered (Listed) Species Concerns

............................... 67

6.1. Action Area

................................ ................................ ................................ ................................ ............. 67

6.2. Taxonomic Groups Potentially at Risk

................................ ................................ ................................ . 68

6.2.1. Probit Dose

- Response Analysis

................................ ................................ ................................ ...... 73

6 .2.2. Listed Species Occurrence Associated with Registered Uses

................................ ....................... 74


### 7. References

................................ ................................ ................................ ............................ 75

7.1 Submitted Product Chemistry and Environmental Fate Studies

................................ ....................... 77

7.2. Submitted Ecotoxicity Studies (Retrieved from OPPIN November 19, 2012)

................................ ... 81



### Appendices

Appendix A: PRZM/EXAMS output for highest cotton and tree injection scenarios

......... 87 Appendix B: Toxicity Categories and Levels of Concern

................................ ....................... 96 Appendix C: Example T

- REX (v. 1.5) Input and Output for Dicrotophos

........................... 97 Appendix D: STIR Results

................................ ................................ ................................ ......... 99 Appendix E: SIP Results

................................ ................................ ................................ .......... 100

A ppe nd i x F : A cce p t ed E C O T O X D a t a Ta b l e

................................ ................................ ......... 101- Page 10 of 102

-



### 1. Executive Summary

The Environmental Fate and Effects Division ( EFED ) has completed the Registration Review preliminary ecological risk assessment for dicrotophos [(E)

- 4

- dimethylamino

- 4

- oxobut

- 2

- en

- 2

- yl] dimethyl phosphate; CAS Registry Number 141

- 66

- 2 ; PC Code 035201) and its end

- use product s

. D icrotophos is broad

- spectrum systemic organophosphate insecticide that provides control of insect pests on a contact basis while also being suitable for residual crop protection since it is readily taken up by plant tissue. It is currently registered for broadcast appl ications only on cotton (applied as a liquid foliar spray via air or ground application equipment) and as a tree injection (applied as capsules into holes drilled in the tree trunk)

. Th is preliminary risk

assessment examines the potential ecological risks associated with labeled uses of dicrotophos based on the best available scientific and commercial information on the use, environmental fate and transport, and effects of dicrotophos on nontarget organisms

.

Dicrotophos is expected to readily degrade in both terrestrial and aquatic environments under

aerobic and anaero bic conditions, and is mobile and semivolatile to nonvolatile. Dicrotophos is not persistent in soil with a single aerobic half

- life 2.7 days and a half

- life of 8 days in anaerobic

soil. Dicrotophos is relatively stable to hydrolysis (t 1/2 

### = 72 days) and stable to photolysis. The major degradates of dicrotophos degrade readily in aerobic conditions.

Aquatic exposure estimates for dicrotophos are presented for the parent compound and total

toxic residues ( i.e. , parent dicrotophos plus transformation products: SD 6167, SD 11733, and

SD 228001 )

. Acute 1

- in

- 10 year estimated environmental concentrations (EECs) in surface

water for modeled cotton uses of dicrotophos ranged from 13 μg/L to 17 μg/L for total toxic residues, and 12 μg/L to 16 μg/L for parent dicrotophos alone

. The highest reported surface

water monitoring value (6.83 μg/L) is approximately half of the peak modeled value s ; higher dicrotophos detections may be found with more targeted monitoring approaches. Parent

- only and total toxic residue concentrations are similar because dicrotophos dissipation is driven by

aerobic metabolism and the dicrotophos transformation products metabolize readily.

T errestrial and aquatic exposure resulting from the tree injection use pattern

— which cannot be assessed via EFED’s usual “pounds active ingredient per acre” application rate modeling paradigm

— were evaluated according to multiple translocation and fate scenarios of varying degre es of conservatism ( e.g. , equal distribution across all tree tissue, 100% translocation to the leaves; described in detail in Section 3.2 )

.

Dicrotophos is very highly toxic to aquatic invertebrates on an acute exposure basis. Chronic dicrotophos exposur es adversely affected aquatic invertebrate growth, with length and weight

reductions seen at concentrations as low as 1.7 μ g ai/L in freshwater invertebrates and as low as

6.15 μ g ai/L in estuarine/marine invertebrates

. Dicrotophos is slightly to moderately toxic to fish

on an acute basis , and no adverse chronic effects were recorded at concentrations as high as
9,880 μg ai/L in the available fish early life stage study

. T he screening level assessment with preliminary refinements concludes that th e use of dicrotophos in accordance with registered

labels results in acute and chronic risk to aquatic invertebrates that exceed both the Agency’s

acute and chronic risk Level of Concern (LOC) , but does not result in acute or chronic risk to

fish that exce eds the Agency’s LOC s

. Estimates of r isk to aquatic plant s do not exceed the- Page 11 of 102

-



### Agency’s risk LOC

.

D icrotophos is very highly toxic to birds and mammals on an acute exposure basis , and available data suggest chronic toxicity concerns . A three

- generation study on reproduction and fertility in Norway rat s showed dicrotophos to cause chronic adverse effects in terms of decreased pup survival at 5 mg/kg

- diet

. In chronic avian reproduction testing

, statistically significant effects to egg production and femal e body weight were recorded at exposure concentration s as low as 1.5 mg/kg

- diet

. T he screening level assessment with preliminary refinements concludes that the use

of dicrotophos in accordance with registered labels results in acute and chronic risk to av ian and mammalian species that exceed both the Agency’s acute and chronic risk LOC. Dicrotophos is

classified as highly toxic to honey bees , and the acute risk to terrestrial invertebrates exceeds the Agency’s risk LOC

. No statistically significant effec ts to terrestrial plants were determined in Tier I testing with dicrotophos applied at the maximum label rate ; risk to terrestrial plants does not exceed the Agency’s risk LOC

.

Specific to the dicrotophos tree injection use pattern, there is uncertainty in the acute and chronic risk estimates and corresponding risk LOC exceedances for birds, mammals, terrestrial invertebrates, and aquatic invertebrates in the absence of data describing the magnitude of

residues in tree tissue and exudate (s) and the dispersion of treated trees across the landscape.

Potential effects to federally

- listed endangered and threatened species (listed species) based on LOC exceedances require an in

- depth listed species evaluation determining the potential co

occurrence of li sted species and use patterns of dicrotophos . Identified potential risks to listed species are summarized in Table 1

.

Table 1. Potential Effects to Federally Listed Taxa Associated with Direct Effects from the Registered Us es of Dicrotophos.

Listed Pla nt Taxon Potential Direct Effects

Terrestrial and semi

- aquatic plants

– monocots and dicots No

Aquatic nonvascular plants No Aquatic vascular plants No

Listed Animal Taxon Potential Direct Effects

Acute Chronic

Terrestrial invertebrates Yes ND

Mammals Yes Yes

Birds Yes Yes Reptiles Yes Yes

A mphibians Uncertain 1 Uncertain 1

Freshwater fish No No

Freshwater invertebrates Yes 2 Yes 2

Mollus k s No ND

E stuarine /marine fish No No

E stuarine /marine invertebrates Yes 2 Yes 2

ND = Not determined

1 Freshwater fish are surrogates for aquatic

- phase amphibians, and birds are surrogates for terrestrial

- phase amphibians. Since direct effects are predicted for birds, but not for fish, it is presumed that amphibians consuming terrestrial food items may exp erience potential direct effects, whereas the potential for direct effects to aquatic

- phase amphibians is unlikely.

2 Potential direct effects are uncertain for the tree injection use pattern.- Page 12 of 102

-



### 2. Problem Formulation

The purpose of problem formulation is to provide the foundation for the environmental fate and ecological risk assessment for the registration review risk assessment for the insecticide dictrotophos

, [(E)

- 4

- dimethylamino

- 4

- oxobut

- 2

- en

- 2

- yl] dimethyl phosph ate ; CAS #: 141

- 66

- 2 ; PC code: 035201 ). The problem formulation sets the objectives for the risk assessment, establishes a risk hypothesis and conceptual model depicting potential risk, and provides a plan for analyzing the data and characterizing the risk associated with the use s of dicrotophos (USEPA, 1998).

2.1. Nature of Regulatory Action

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), all pesticides distributed or sold in the United States must be registered by the United States Environmental Protection Agency (USEPA). To determine whether a pesticide can be registered, the USEPA 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 (FQPA), and EPA was mandated to implement a new program for the periodic review of pesticides, i.e ., registration

review 1 

### . 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. T hrough the registration review program, the Agency periodically reevaluates pesticides to make sure that as change s occur , products in the marketplace can be used safely.

2.2. Stressor Source and Distribution

2.2.1. Nature of Chemical Stressor

Dicrotop hos is a contact, systemic organophosphate insecticide. Organophosphates share a common mode of action, binding to the enzyme acetylcholinesterase ( AChE ), an important enzyme in the nervous system of animals

. As dicrotophos binds to AChE , the availabilit y of the neurotransmitter acetylcholine increases , resulting in paralysis from overstimulation of the

nervous system . This mode of action is no t specific to invertebrates and chemically

- mediated

e ffects are observed in vertebrates as well.

Dicrotophos is registered for use on cotton and in tree injections. This assessment is based on currently labeled maximum a pplication rates for all uses. Specific use rates are discussed in

Section 3.1

.

Four products containing dicrotophos are registered: Bidrin 8 ( EPA Reg. No. 5481

- 448), Bidrin XP (EPA Reg. No. 5481

- 552), Bidrin XP II (EPA Reg. No. 5481

- 9024), and Mauget Inject

- A

Cide B (EPA Reg. No. 7946

- 11). Bidrin 8, Bidrin XP, and Mauget Inject

- A

- Cide B are 82% dicrotophos. Bidrin XP and Bidrin XP II are co

- fo rmulated with bifenthrin (PC code: 128825 ) , a

1 http://www.epa.gov/oppsrrd1/registration_review/- Page 13 of 102

-



### pyrethroid insecticide . Bidrin 8, Bidrin XP, and Bidrin XP II are labeled for use on cotton only. For use on cotton, dicrotophos can only be applied by ground spray or aerially. Mauget Inject

A

- Cide B is la b eled for tree injection only.

2.2.2. Overview of Pesticide Usage

Though labels indicate potential use of dicrotophos, usage data allows for more accurate characterization of actual use of dicrotophos. Data for usage on cotton is derived from USDA National Agricultural Statistics Service, private pesticide market research, and the California Department of Pesticide Reg ulation 2 

### . Average annual amount of dicrotophos applied to cotton is 900,000 pounds with an average percent crop treated of 15% and a maximum percent crop

treated of 20%.

Usage information on the tree injection use pattern was provided by the product registrant, J.J. Mauget Co. The tree injection capsules distributed contain 82% dicrotophos active ingredient.

2.3. Receptors

2.3.1. Aquatic and Terrestrial Effects

In ecological risk assessment, a receptor is a biological entity that is exposed to a stressor (USEPA, 1998). Consistent with the process described in the Overview Document (USEPA, 2004), this risk assessment uses a surrog ate species approach in its evaluation of dicrotophos

. Toxicity data generated using surrogate test species, which are intended to be representative of broad taxonomic groups, are used to infer potential effects on a variety of species (receptors)

include d under these broader taxonomic groupings. Table 2. 1 provides the general taxonomic groups and surrogate species tested to evaluate potential ecological effects of dicrotophos to
broad classes of non

- target organisms. Within each of these taxonomic group s, a measure of effect is selected from among the available test data.

Table 2. 1 . Taxonomic Groups and Test Species Evaluated for Assessing Potential Ecological Effects of D icrotophos

.

Organismal Group Typical Species

Birds 1 Mallard duck ( Anas platyrhynchos ) Bobwhite quail ( Colinus virginianus )

Mammals Norway rat ( Rat t us norvegicus )

Invertebrates Honey bee ( Apis mellifera L. )

Freshwater fish 2 Bluegill sunfish ( Lepomis macrochirus ) Rainbow trout ( Oncorhynchus mykiss ) Fathead minnow ( Pimephales promelas )

Freshwater invertebrates Water flea ( Daphnia magna ) Midge ( Chironomus riparius )

Estuarine/marine fish Sheepshead minnow ( Cyprinodon variegatus )

Estuarine/marine invertebrates Mysid ( Americamysis bahia ) Eastern oyster ( Crassostrea virginica ) Terrestrial plants 3 Monocots

– Crop species, such as corn ( Zea mays )

Dicots

– Crop Species, such as soybean ( Glycine max )

2 Dicrotophos is not registered for use on cotton in California- Page 14 of 102

-



### Table 2. 1 . Taxonomic Groups and Test Species Evaluated for Assessing Potential Ecological Effects of D icrotophos

.

Organismal Group Typical Species Aquatic plants and algae Duckweed ( Lemna gibba ) Freshwater Algae ( Pseudokirchneriella subcapitata )

1 Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

2 Freshwater fish may be surrogates for aquatic

- phase amphibians.

3 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of w hich one is soybeans.



### 2.3.2. Ecosystems Potentially at Risk

The ecosystems potentially 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 or tree(s) and immediately adjacent areas that may receive drift or runoff. Areas adjacent to the treated field or tree(s) could include cul tivated 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 downstream from use sites, and might in clude impounded bodies such as ponds, lakes and reservoirs, or flowing waterways such as streams or rivers including all adjacent off

- channel habitats that are permanently or intermittently connected to flowing waters. For uses in coastal areas, aquatic

ha bitat also includes marine ecosystems, including estuaries, embayments, and near

- shore

environments such as tidal marshes.

2.4. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by an ecological entity (species, community, or other entity) and its attribute or characteristics (USEPA, 1998). For dicrotophos , ecological entities of potent ial concern include the following: birds, amphibians, reptiles, mammals, freshwater fish and invertebrates, estuarine/marine fish and invertebrates, non

- target terrestrial plants, terrestrial invertebrates, and aquatic vascular and

non

- vascular plants. T he attributes for each of these entities include growth, survival, and reproduction ( Table 2. 3 in Section 2.6.4 ).

2.5. 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 mecha nism, an environmental transport mechanism, and a feasible route of exposure.

The conceptual model is intended to provide a written description and visual representation of anticipated relationships between dicrotophos, potential routes of exposure, and t he predicted effects for the assessment endpoints. The conceptual model consists of two major components: risk hypotheses and a conceptual diagram (USEPA, 1998).- Page 15 of 102

- 

### 2.5.1. Risk Hypotheses

For dicrotophos, the following gener ic ecological risk hypotheses are being employed for this screening

- level risk assessment:

Given the currently labeled uses of dicrotophos and its environmental fate properties, there is a likelihood of exposure to non

- target terrestrial and aquatic organisms.

When used in accordance with the label, dicrotophos may result in potential adverse effects upon the survival, growth, and reproduction of non

- target terrestrial and aquatic organisms.

2.5.2. Conceptual Diagram

The conceptual model is a graphical representation of predicted relationships between ecological

receptors, both listed (threatened and endangered) and non

- listed, and the stressors to which they may be exposed. A conceptual model specifies potential routes of exposure, biological receptor types, and effects endpoints of potential concern.

Dicrotophos is exp ected to degrade quickly in both terrestrial and aquatic environments under aerobic and anaerobic conditions, and is considered mobile and nonvolatile. Aerobic and anaerobic metabolism are major routes of degradation. The major degradates of dicro tophos

includ e SD6167, SD228001, and SD11733.

Figure 2.1 depicts the stressors, exposure pathways, and potential effects to terrestrial organisms from currently labeled uses of dicrotophos. Figure 2.2 depicts the stressors, exposure pathways, and potential effects to aquatic organisms from currently labeled uses of dicrotophos. For both figures, dotted lines indicate exposure pathways that are expected to have a low likelihood of contributing to ecolog ical risk.- Page 16 of 102

-



### Figure 2.1. Conceptual model for dicrotophos effects on terrestrial organisms

. 

## Stressor

Source

Receptors

Attribute Change Dicrotophos applied to use site

Direct application

Birds / Terrestrial

phase amphibians / reptiles /

mammals Seeds and

Leaves

Individual organisms

Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey Habitat integrity Reduction in primary productivity

Reduced cover Community change Terrestrial/riparian plants grasses/forbs, fruit, terrestrial

invertebrates Runoff

Mammals/

Birds 

## Exposure

Media Soil

Ingestion Ingestion

Ingestion Ingestion Dermal uptake/Ingestion

Root uptake

Wet/dry deposition

Mammals/Birds /Amphibians Ingestion- Page 1 7 of 102

-



### Figure 2.2. Conceptual model for dicrotophos effects on aquatic organisms.



### 2.6. Analysis Plan

2.6.1. Residues of Concern

Major degradates of dicrotophos ( i.e. those constituting greater than 10% of the applied radiation from environmental fate studies) are SD 6167, SD 11733, and SD228001

. Dicrotophos readily

metabolizes to SD 6167 in aerobic soil. Concentrations of SD 11733 and SD 228001were not determined in the aerobic soil metabolism study though formation is possible given other sources of radiation peaked during Day 1 o f the study at 5.5% of applied radioactivity (See Table 3.4)

. Dicrotophos metabolizes to SD 11733 in anaerobic soil with concentrations as high as 12.7% of applied radioactivity at study conclusion (33 days).

2.6.2. Preliminary Identification of Data Gap s and Uncertainties

The tree injection use pattern (EPA Reg. No. 7946

- 11) does not limit the number of applications that can be made in a given year or season. Further, the stated application rate is based on number of capsules for a given tree size. H owever, the size of the capsule can be variable according to the label which would result in substantially different applications depending on capsule size. The fate of dicrotophos when injected into the tree is also a great uncertainty. The 

## Stressor

Source

Receptors

Attribute Change Dicrotophos applied to use site

Fish/aquatic

- phase amphibians Eggs

Larvae

Juveniles / Adults

Individual organisms

Reduced survival Reduced growth Reduced reproduction Food chain

Reduction in algae Reduction in prey Habitat integrity Reduction in primary productivity

Reduced cover Community change Surface water/

Sediment Runoff

Aquatic Animals

Invertebrates

Vertebrates 

## Exposure

Media

Uptake/gills

or integument

Ingestion Ingestion Wet/dry deposition Soil Groundwater

Uptake/gills or integument

Aquatic Plants

Non

- vascular

Vascular Uptake/cell,
roots, leaves Riparian plant

terrestrial

exposure pathways see Figure 2.1- Page 18 of 102

-



### rates of deg radation in the tree, mobility to various parts of the tree, and formation of degradates cannot be characterized by current data. Though it is not formed in soil metabolism, it is possible that monocrotophos is formed in the tree as it was found in a dicr otophos dislodgeable foliar residue study on cotton (MRID 44731001) 4 days following the last application at 1.6% of the maximum detected applied radioactivity and detected in a plant metabolism study (MRID 13505) . This degradate of dicrotophos is more to xic to many taxa than dicrotophos itself.

2.6.3. Evaluation of Multiple Active Ingredients

, Mixtures and Formulated

Products

The Agency does not routinely include in its risk assessments an evaluation of mixtures of active ingredients, either those m ixtures of multiple active ingredients in product formulations or those in the applicator’s tank. In the case of the product formulations of active ingredients (that is, a registered product containing more than one active ingredient), each active ingredi ent is subject to an individual risk assessment for regulatory decision regarding the active ingredient on a particular use site. If effects data are available for a formulated product containing more than one active ingredient, they may be used qualitati vely or quantitatively in accordance with the Agency’s Overview Document and the Services’ Evaluation Memorandum (U.S. EPA 2004; U.S. FWS/NMFS 2004).

In the case of dicrotophos

, no data on the formulated product s Bidrin XP and Bidrin XP II are available for fish, aquatic invertebrates, and aquatic and terrestrial plants and mammals.
However, as these products contain bifenthrin, the effects on invertebrates are expected to be

enhanced.

2.6.4. Measures of Exposure

Measures of exposure are based on aquatic and terrestrial models that estimate environmental

concentrations of dicrotophos using labeled application rates and methods. For aquatic exposure the Tier II model Pesticide Root Zone Model (PRZM v3.12.2; May 12, 2005) linked with EXposure Analysis Modeling System (EXAMS v2.98.4.6; Apr. 25, 2005) via the PRZM/EXAMS model shell (PE v5.0, Nov. 15, 2006), i.e. , PRZM/EXAMS) were used to estimate screening

- level exposure concentrations in aquatic environments. The mea sure of exposure for aquatic species in surface water bodies receiving runoff and/or spray drift is a return frequency of 1

- in

- 10 years of the estimated environmental concentrations (EEC), based on 30

- year simulations. The maximum 1

- in

- 10 year return freq uency concentration is used for estimating acute exposures to aquatic organisms (plants and animals); the 1

- in

- 10 year 21

- day mean concentration is used for assessing aquatic invertebrate chronic exposure; and the 1

- in

- 10 year 60

- day mean concentration is used for assessing chronic exposure for fish (and aquatic

phase amphibians for which fish serve as surrogates). EECs for dicrotophos include degradates of dicrotophos in total toxic residues (TTR) approach. These residues include SD 6167, SD 11733, and S D228001.

Terrestrial wildlife are exposed to dicrotophos via consumption of residues on food items generated by spray applications. For spray applications, the T

- REX model ( T errestrial R esidue- Page 19 of 102

-



### EX posure model; v. 1.5; March 22, 2012) is used to predict die tary exposure to dicrotophos residues on foliar surfaces and insects using the Kenaga nomogram as modified by Fletcher (Hoerger and Kenaga 1972, Fletcher et al. 1994). A default 35

- day foliar dissipation half

- life is used for terrestrial exposure modeling in this assessment. Foliar dissipation data specific to dicrotophos ( e.g., Willis and McDowell 1987) are not available. Use

- specific input values, including number of applications, application rate and application interval are also inputs.

To characterize potential nontarget bird and mammal exposure from spray drift alone, Tier 1 modules in AgDRIFT (v. 2.1.1, December 2011) were used to estimate how far off

- site spray drift exposure might occur at a level known to cause adverse effects in bird and mammal toxicity

studies.

The S creening T ool for I nhalation R isk (STIR v.1.0, November 19, 2010) was used to calculate an upper bound estimate of exposure using dicrotophos ’s vapor pressure and molecular weight for vapor phase exposure as well as the m aximum application rate and method of application for spray drift. STIR incorporates results from several toxicity studies including acute oral and inhalation rat toxicity endpoints obtained from the “six

- pack” of core studies, which are a series of six gu ideline studies that are submitted to the Registration Division of the Office of Pesticide Programs for technical and formulated products 3 

### of a pesticide ( LD 50 

### 8 mg/kg bw, MRID

43893901 ; and inhlation LC 50 

### >0 .0 5 9 mg/L, MRID 46 411001 , respectively) as well as the most sensitive acute oral avian toxicity endpoint ( domestic goose LD 50 

### 1.22 mg/kg bw, MRID

00013439 ). Based on the results of the STIR model ( Appendix D ), exposure through inhalation of spray drift or the vapor phase of dicrotophos was det ermined to be a potential pathway of

concern for avian species on an acute exposure basis but not, however, for mammalian species.

The analysis of the inhalation route in STIR does not consider that aggregation with other exposure pathways such as dietary , dermal, or drinking water may contribute to a total exposure that has a potential for effects to nontarget animals. However, the Agency does consider the relative importance of other routes of exposure in situations where data indicate that pesticide

ex posures through other routes may be potentially significant contributors to wildlife risk (USEPA 2004). The risk characterization section ( Section 4.3 ), discusses the impact of consideration of other routes of exposure that have been identified as potenti ally important and the degree of certainty associated with screening

- level risk assessment conclusions. Detailed information about STIR v.1.0, as well as the tool, can be found on EPA’s website ( http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial ).

The S creening I mbibition P rogram (SIP v.1.0, released June 15, 2010) was used to calculate an upper bound estimate of exposure using dicrotophos ’s solubility ( 11,990 mg/L, MRID

43603202 ), and compared to the most sensitive ac ute and chronic avian and mammalian toxicity endpoints ( see Table 3. 1 2 ). Drinking water exposure alone was determined to be a potential

p athway of concern for avian and mammalian species on both an acute and a chronic exposure

basis. For a sample of the output genera ted by SIP v.1.0, please see Appendix E

.

3 Note that all STIR toxicity value inputs are the result of testing with techni cal grade active ingredient since no

“six

- pack” studies are available for dicrotophos formulated products.- Page 20 of 102

- 

### 2.6.5. Measures of Effect

Measures of effect are obtained from a suite of registrant

- submitted guideline studies that were conducted with a limited number of surrogate test species ( Table 2. 2 )

. A dditional ecotoxicity

data on dicrotophos were located, based on a May 2012 query of the open literature in the publically available v ersion of the ECOTOX icology database ( ECOTOX; http://cfpub.epa.gov/ecotox/ ) to identify whether additional, more sensitive ecological effects data were available for dicrotophos; however, no more useful data we re identified (USEPA 2012).

The acute measures of effect used in this baseline assessment are the LD 50 

### (median Lethal Dose),

LC 50 

### (median Lethal Concentration) or EC 50 

### (median Effects Concentration). These are measures of acute toxicity which result in 50% of the respective effect in tested organisms. The endpoints for chronic measures of exposure are the no observed adverse effect concentration (NOAEC) and the no obs erved adverse effect level (NOAEL). Toxicity studies were submitted for freshwater fish and invertebrates, estuarine/marine fish and invertebrates, aquatic plants, birds, mammals, bees, and other terrestrial invertebrates. The endpoints used for risk

cha racterization are derived from studies which underwent review and were classified as “acceptable” (conducted under guideline conditions and considered to be scientifically valid) or “supplemental” (conditions deviated from guidelines but the results are co nsidered to be scientifically valid).

Table 2. 2 lists the measures of environmental exposure and ecological effects used to assess the potential risks of dicrotophos to non

- target organisms. The methods used to assess the risk are

consistent with those outlined in the document “Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs” (USEPA, 2004).- Page 21 of 102

-



### Table 2. 2 . Measures of Exposure and Measures of Effect Used in Assessing Potential Risks Associated with the Proposed Uses of D icrotophos

.

Assessment Endpoint Surrogate Species and Measures of Ecological Effect 1 Measures of Exposure

Birds 2 Survival Lowest acute LD 50 (single oral dose test)

and LC 50 (subacute dietary test) Upper

- bound residues on

food items

Reproduction

and Growth Lowest NOAEC

(21

- week reproduction test)

Mammals Survival Lowest acute LD 50 (single oral dose test)

Reproduction

and Growth Lowest NOAEC

(2

- generation reproduction test)

Aquatic Animals (Fish and invertebrates) 3 Survival Lowest tested LC 50 or EC 50 (acute toxicity test) Peak EECs 4

Reproduction

and Growth Lowest NOAEC (early life

- stage or full

life

- cycle tests) 21

- day EECs for invertebrates

and 60

- day EECs for fish 4

Terrestrial plants 5 Survival and growth Lowest EC 25 (for non

- listed plants) and

corresponding NOAEC (for listed

plants)

(endpoints derived for monocots and dicots from seedling emergence and vegetative vigor studies) Estimates of runoff and spray

drift to non

- target areas

Insects 6 Survival Lowest honeybee LD 50 (acute contact test) Upper

- bound residues on tall

grass 7

Aquatic plants (vascular

and non

- vascular) Survival and growth Lowest EC 50 (for non

- listed plants) and

corresponding NOAEC or EC 05 (for

listed plants) Peak EECs 4

1 The most sensitive species tested within taxonomic groups is used for screening

- level risk assessments.

2 Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

3 Freshwater fish represent surrogates for aquatic

- phase amphibians.

4 Aquatic EECs are based on modeling described in Section 3.2.2.1

. 5 Four species of two families of monocots

- one is corn, six species of at least four dicot fa milies, of which one is soybeans.

6 Risk to terrestrial invertebrates from dicrotophos use is quantitatively evaluated against the acute listed terrestrial invertebrate LOC of 0. 4

. 7 T he tall grass residue value from the T

‐ REX model (v. 1.5) is used as a surrogate for dicrotophos concentrations in nectar and pollen

.



### 2.6.6. Integration of Exposure and Effects

Exposure and toxicity data are integrated in order to evaluate the risks of adverse ecological

effects on non

- target species. For the scree ning

- level risk assessment of dicrotophos , the deterministic risk quotient (RQ) method is used to compare estimated exposure concentrations with measured toxicity values. The RQ method involves dividing point estimates of environmental concentrations by a cute and chronic toxicity values. The resulting unitless RQs are then compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004) ( Table 2. 3 )

. These criteria are used to indicate when applications of dicrotophos , as directed on the registered labels,

h ave the potential to cause adverse effects to listed and non

- listed non

- target organisms.- Page 22 of 102

-



### Table 2. 3 . Agency Risk Quotient (RQ) Metrics and Levels of Concern (LOC) Per Risk

Class.

RISK CLASS RISK DESCRIPTION RQ LOC

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non

- listed animals from acute

exposures Peak EEC/LC 50 1 0.5

Acute

Restricted Use Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification Peak EEC/LC 50 1 0.1

Acute Listed Species Listed species may be potentially affected by acute

exposures Peak EEC/LC 50 1 0.05

Chronic Potential for effects to non

- listed and listed animals from

chronic exposures 60

- day EEC/NOAEC (fish) 1 21

- day EEC/NOAEC (invertebrates)

Aquatic Plants

Non

- Listed Potential for effects to non

- listed plants from exposures Peak EEC/LC 50 1 1

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC 1

Terrestrial Animals (mammals and birds)

Acute Potential for effects to non

- listed animals from acute

exposures EEC/LC 50 (Dietary) 0.5 EEC/LD 50 (Dose)

Acute

Restricted Use Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification EEC/LC 50 (Dietary) 0.2 EEC/LD 50 (Dose)

Acute Listed Species Listed species may be potentially affected by acute

exposures EEC/LC 50 (Dietary) 0.1 EEC/LD 50 (Dose)

Chronic Potential for effects to non

- listed and listed animals from

chronic exposures EEC/NOAEC 1

Terrestrial and Semi

- Aquatic Plants

Non

- Listed Potential for effects to non

- target, non

- listed plants from

exposures EEC/ EC 25 1

Listed Plant Potential for effects to non

- target, listed plants from

exposures EEC/ NOAEC 1 EEC/ EC 05

1 LC 50 or EC 50

.



### 3. Analysis

3.1

. Use Characterization

Use patterns

National Labels



### Four products containing dicrotophos are registered: Bidrin 8 (EPA Reg. No. 5481

- 448), Bidrin XP (EPA Reg. No. 5481

- 552), Bidrin XP II (EPA Reg. No. 5481

- 9024), and Mauget Inject

- A

Cide B (EPA Reg. No. 7946

- 11). Bidrin 8, Bidrin XP, and Mauget Inject

- A

- Cide B are 82% dicrotophos. Bidrin XP and Bidrin XP II are co

- formulated with bifenthrin (PC code: 128825 ) , a- Page 23 of 102

-



### pyrethroid insecticide . Bidrin 8, Bidrin XP, and Bidrin XP II are labeled for use on cotton only. Mauget Inject

- A

- Cide B is labeled for tree injection only.

For use on cotton, di crotophos can be applied only by ground spray or aerially. It can be applied early season (emergence to pre

- bloom) at 0.2 lb a.i./A and late season (first bloom to 30 days pri or to harvest) at 0.5 lb a.i./A . One application may be made early season and t wo applications may be made late season for a maximum seasonal app lication rate of 1.2 lbs a.i./A . Dicrotophos is applied to cotton to control thrips, cotton fleahoppers, aphids, spider mites, grasshoppers, boll weevils, leaf footed bug, plant bugs, and s tink bugs. Products co

- formulated with bifenthrin control additional pests.

For the tree

- injection use pattern, application timing is dependent on the appearance or life stage of the target pest. Injections are made via holes drilled into the base of a given tree where 1, 2 or 3 milliliter capsules are injected (82% a.i.). The number of capsules to be applied is determined by measuring the diameter of the tree at chest height and dividing by two. The size of the capsule is not specified in this applica tion calculation. The following tree species are listed on

the label : Ash, Beech, Birch, Flowering crabapples (non

- crop), Dogwood, Elm, Black Gum, Hackberry, Linden, Locust, Maples (non

- crop), Oaks, Pines, Flowering Stone Fruit (non

- crop), Sycamore (Plane Tree), and Willow. The label contains no clause which explicitly limits applications to those species included on the label.

Use patterns for 

### dicrotophos are presented in Table 3.1

.

Table 3.1. Use Patterns for D icrotophos

Crop Registration (application timing) Max single application Max season

application Min interval

(days) Tree Injection

National (Pest dependent) Diameter of tree (inches) divided by two equals

number of 3 mL capsules to insert N ot specified Not specified

Cotton National (Emergence to 30 days

pre

- harvest) 0.5 lb a.i./A 1.2 4 14



### 3.2. Exposure Characterization

3.2.1. Environmental Fate and Transport Characterization

The general physical/chemical properties of dicrotophos are summarized in Table 3.2

. Environmental fate and transport properties of dicrotophos are characterized in further detail in the following sections. The Agency’s understanding of these properties is limited by the

available dataset.

Table 3.2 General Physical and Chemical Prope rties of Dicrotophos

Property Value Reference

Chemical Name ( 

### E )

- 2

- dimethylcarbamoyl

- 1

-

4 An early season application at 0.2 lb/A is allowed by the dicrotophos cotton labels- Page 24 of 102

-

(IUPAC) methylvinyl dimethyl phosphate

CAS Registry Number 141

- 66

- 2 Dicrotophos RED

Molecular Formula C 8 H 16 NO 5 P Dicrotophos RED

Molecular Weight g/mol 237.19 Calculated

Physical State Yellow brown liquid MRID 40188003

Vapor Pressure, mmHg 7.0E

- 5 @ 25 oC MRID 43500401

Aqueous Solubility, mg/L 11,990 MRID 43603202, MRID 43603201

Octanol

- Water

Partition Coefficient ( Log K
ow ) 0.3883 (E

- isomer)

- 3.318 (Z

- isomer) MRID 43603204

Henry’s Law Constant 3.13 E

- 11 atm

- m 3 /mol Calculated from vapor pressure and solubility



### When dicrotophos is released into the environment, it degrades quickly primarily via aerobic soil

metabolism. Dicrotophos is not persistent (field dissipation half

- life of 2.2 days) in the environment, is mobile in soil (estimated average K
oc 

### value is 73 ml/g o.c.), and has a very high solubility. It is not expected to accumulate in ground water because of its short half

- life. A summary of the submitted environmental fate and transport data is summarized below in Table

3.3

.

Degradates of dicrotophos include SD 228001, resulting from demethylation at the phosphate group, and SD 6167 and SD 11733 resulting from c leavage at the phosphate group. SD 6167 was detected in submitted hydrolysis, aerobic and anaerobic soil metabolism studies. SD 11733 and SD 228001 were detected in the anaerobic soil metabolism and hydrolysis studies, respectively.

Table 3.3 Environmental Fate Data Summary for Dicrotophos

Input Parameter Value Source/comment

Hydrolysis half

- life pH 5: 117 days @ 25C pH 7: 72 days @ 25C pH 9: 28 day @ 25C MRID 160823

.

Aqueous Photolysis half

- life Stable MRID 160824

Soil Photolysis half

- life Stable MRID 16082 5

Aerobic Soil metabolism half

- life 2.7 days \ MRID 160826

Anaerobic Soil metabolism half

- life 8 days MRID 160827 Degradation data on SD6167 was requested in DER

Anaerobic aquatic metabolism half

life No data Assumed stable

Aerobic Aquatic metabolism half

- life No data Assumed stable

Organic carbon normalized soil partition coefficient Koc 73 mL/ g o.c. MRID 160828

Adsorption Coefficient 1.24 mL./g MRID 160828- Page 25 of 102

-

Input Parameter Value Source/comment

Terrestrial field dissipation 2.2 days MRID 41114301



### 3.2.1.1. Transport and Mobility

Dicrotophos is transported off site primarily through spray drift leaching , and runoff for the

cotton use pattern . Through the tree injection use pattern, dicrotophos is transported off site through run off, from residues contained within tree litter, and leaching.

Dicrotophos is not volatile, with a vapor pressure of 7.0E

- 5 torr at 25 oC and a Henry’s law

constant of 3.13*10

- 11 

### atm

- m 3 

### /mol . The reported log K
ow 

### for dicrotophos at 25oC for pH 7 was

- 0.5

.

Dicrotophos is mobile based on FAO Soil Mobility Classification Guidance (USEPA, 2006a),

with estimated adsorption coefficients ranging from 0.07 to 3.58 mL/g. Adsorption correlates most with clay content as opposed to organic carbon content

. Th erefore th e adsorption constant (K D 

### ) is used for modeling purposes as opposed to the organic carbon partition coefficient (K OC 

### ).

3.2.1.2. Degradation

Dicrotophos hydrolyzes at all tested pHs with degradation increasing with increasing pH. Half

lives range from 117 days to 28 days from pH 5 to pH 9 at 25 o 

### C (MRID 160823 

### ). It is stable to photolysis in water and on soil (MRIDs 160824 and 160825 

### ).

Dicrotophos biodegrades quickly in aerobic soil, with a reported half

- life of 2.7 days (parent

only half

- life; MRID 160826). Dicrotophos readily metabolizes to SD 6167 in aerobic soil.

Concentrations of SD 11733 and SD 228001were not determined in the aerobic soil metabolism study though formation is possible given other source s of radiation peaked during Day 1 of the study at 5.5% of applied radioactivity. Dicrotophos metabolizes to SD 11733 in anaerobic soil with concentrations as high as 12.7% of applied radioactivity at study conclusion (33 days).

Figure 3.1 illustrates a predicted degradation pathway under aerobic conditions

.- Page 26 of 102

-



### Figure 3.1 Predicted Transformation Pathway under Aerobic Conditions

3.2.1.3. Field Studies

One terrestrial field dissipation study has been submitted for a silt loam soil in Mississippi and Georgia though the data from Georgia is unacceptable (MRID 41114301)

. Dicrotophos dissipated with a half

- life of 2.2 days from silt loam soil in Mississippi that was treated three

times at 7

- day intervals with 0.5 lb a.i./A resulting in a total of 1.5 lbs a.i./A applied. Residu e s were not detected below the 0

- 6 centimeter soil horizon. The application interval is shorter (current is 14 days) and seasonal application rate is higher (current is 1.2 lbs a.i. /A) in this study

than current label instructions. Degradates were not analyzed but residues would have likely been present with an aerobic soil metabolism (MRID 160826) detecting SD 6167 at 20% of applied radioactivity 5 days after application.

Monitoring Data

Surface water monitoring data from the USGS National Water

- Quality Assessment Program (NAWQA) and USDA’s Pesticide Data Program for dicrotophos indicate 57 detections in seven states (Colorado, Georgia, Louisiana, Minnesota, Mississippi, N orth Carolina, and Texas) from approximately 8,500 samples. The peak detection of 6.83 parts per billion occurred in Washington County, Mississippi on Bogue Phalia in 2005. All other detections were for concentrations less than 0.3 parts per billion. It a ppears targeted monitoring was occurring at the site as 14 samples resulted in 14 detections between the days of June 21 and August 24 from 

# Dicrotophos

SD

6167 SD

22800



# 1

SD

11733- Page 27 of 102

-



### 2005 to 2008. Sample frequency varied drastically though sampling occurred on consecutive days in some instances in cluding the day following the peak detection of 6.83 ppb. The subsequent concentration was 0.17 ppb. This rapid reduction in concentration indicates that peak concentrations are highly likely to be missed without high frequency monitoring. NAWQA

reports 65 detections from 99 samples in Mississippi indicating dicrotophos use areas are targeted among sampling sites. However, targeting monitoring high frequency monitoring around dicrotophos application and precipitation events is not necessarily occurring and peak detections may be missed

No groundwater monitoring data for dicrotophos was found. However, occurrence of dicrotophos in groundwater may be expected since total toxic residues are mobile and persistent to hydrolysis and anaerobic metabolism.

3.2.1.4. Bioconcentration

Dicrotophos is not expec ted to bioconcentrate due to it s low log Kow (

- 3.318 to 0.3883 ) and low

bioconcentration of a structurally similar chemical and metabolite , monocrotophos. Monocrotophos did not bioconcentrate to detectable levels in a static system (LOD = 0.03 ppm; MRID 155661).

3.2.1.5. Environmental Degradates

The major degradates resulting from environmental degradation processes are SD 228001, SD 6167, and SD 11733 ( T able 3.4 ). These transformation products were identified in the environmental fate studies at concentrations >10% of the applied radioactivity and are considered in the environmental exposure assessment

.

In the neutral pH hydrolysis study, the demethyla tion product, SD 228001, formed at concentrations up to 18.8% of applied radioactivity 28 days after treatment

. In an aerobic soil metabolism study, the phosphate group was cleaved forming SD 6167 at concentrations up to 20.0% of applied radioactivity 5 d ays after treatment. In an anaerobic soil metabolism study, SD 11733 formed at concentrations up to 12.6% of applied radioactivity 36 days after treatment.

Considering the tree

- injection use pattern, degradates found in foliar residue studies are of

sp ecial interest as they provide some information related to plant metabolism. Monocrotophos (dimethyl ( E )

- 1

- methyl

- 2

- (methylcarbamoyl)vinyl phosphate) , a demethylation product not found in environmental fate studies, was found in a dicrotophos dislodgeable foliar residue study on cotton (MRID 44731001) 4 days following the last application at 1.6% of the maximum detected applied radioactivity. This detection indicates that monocrotophos may form as a result of plant metabolism and could be a significant me tabolite when injected in trees.- Page 28 of 102

-



### Table 3.4. Table of Transformation Products Formed in Environmental Fate Studies

Common Name IUPAC Name Study in Which Found (Maximum % of Parent, or equivalent) Reference

MRID



### SD 6167 N,N

- dimethyl

- 3

-

oxobutanamide

Aerobic soil metabolism ( 20.0 %, 5 days after treatment) 160826



### SD 228001 {[1

-

(dimethylcarbamoyl)pr

opan

- 2

- yl]oxy}(methoxy)phos phinic acid Hydrolysis, pH 7 ( 18.8 %, 2 8 days after treatment) 160823



### SD 11733 3

- hydroxy

- N,N

dimethylbutanamide Anaerobic soil metabolism ( 12.7 %, 3 6 days after treatment) 16082 7



### Monocrotophos 3

- [(dimethoxyphosphoryl )oxy]

- N

- methylbut

- 2

- enamide Foliar residue study

( 1.6%, 4 days after treatment) 44731001- Page 29 of 102

- 

### 3.2.2. Measures of Aquatic Exposure

3.2.2.1. Surface Water Exposure to Dicrotophos

Surface Water Exposure to Dicrotophos

The Tier II model Pesticide Root Zone Model (PRZM v3.12.2; May 12, 2005; Carousel et al.

, undated) linked with EXposure Analysis Modeling System (EXAMS v2.98.4.6; Apr. 25, 2005; Burns, 2004) via the PRZM/EXAMS model shell (PE v5.0, Nov. 15, 2006), i.e.

, PRZM/EXAMS) were used to estimate screening

- level exposure concentrations in aquatic

envir onments. The PRZM model simulates pesticide movement and transformation on and across the agricultural field resulting from crop applications. The EXAMS model simulates pesticide concentrations in water due to loading via runoff, erosion, and spray drift , assuming a

standard 1

- ha pond, 2

- m deep (20,000 m 3 

### ) with no outlet that borders a 10

- ha treated field. Simulations are for 30 years, from which the Agency estimates peak values that are expected to recur on average once every ten years, based on time series of daily estimated concentrations. The coupled PRZM and EXAMS models and user’s manuals are available from the U.S. Environmental Protection Agency Water Models web

- page (USEPA, 2011b).

Exposure estimates generated using the standard pond are inte nded as surrogates for potential concentrations in a wide variety of vulnerable water bodies, including prairie potholes, playa lakes, vernal pools, other wetlands, man

- made and natural ponds, and ephemeral and first

- order

streams. Innumerable site

- specif ic factors will tend to make such water bodies more or less vulnerable than the standard pond. Static water bodies that have larger ratios of pesticide

- treated drainage area to water body volume are generally expected to have higher peak concentrations

th an the standard pond’s EECs. Such water bodies may be smaller in size, and/or have larger drainage areas. However such water bodies may be more likely to overflow and discharge pesticide in their effluent, whereas the standard pond has no discharge. As watershed size increases, it becomes increasingly unlikely that the entire watershed is planted with a single crop that is all treated simultaneously with a pesticide. Headwater streams may have peak concentrations that are higher than those predicted for the standard pond, but such concentrations will likely persist for only short periods of time or distance, as they are carried downstream and diluted with water originating elsewhere.

The tree injection use pattern is not thought to be a significant sour ce of aquatic exposure. Aquatic exposures could occur from the chemical entering soil environments and subsequently entering aquatic environments. This could occur if the chemical is translocated primarily to the leaves, and the leaves fall to the soil a nd decompose. This exposure pathway was proven realistic in a bioassay where leaves were collected from trees 72 hours after dicrotophos injection

and blended leaves (100 mL water/g of foliage) were introduced into Daphnia pulex cultures

. The bioassay re sults indicate that dicrotophos concentrations in the foliage were higher w h e n the injections were made in multiple bore holes (the same application rate as the treatments with a single bore injection); daphnid mortality ranged from 74% to 100% in these multi

- hole

treatments (Donley, 1967)

. Dicrotophos degrades readily in soil , and through this process of

translocation in the tree and potential foliage degradation over periods longer than 72 hours , it can be expected that dicrotophos will be substantiall y degraded before it reaches aquatic- Page 30 of 102

-



### environments. Preliminary EECs, assuming all dicrotophos applied to the tree is available on the soil surface, indicate values less than half those generated representing the cotton use pattern (Table 3.6 )

. The followi ng conservative assumptions were made in the generation of tree injection EECs: 1) They were generated using the Florida Citrus PRZM/EXAMS scenarios, one

of the more conservative PRZM/EXAMS scenarios. Dicrotophos is not likely to be used in

citrus orchard s though it is not specifically restricted on the label. 2) One 72” DBH tree is assumed to be treated per acre throughout the watershed of concern. Considering the labor intensive application method, it is not likely that trees will be consistently treat ed throughout a landscape and/or watershed 3) The model inputs assume all applied dicrotophos is translocated, undegraded, to the leaves which fall uniformly and make available the full application at a single point in time across all treated trees in a wa tershed. The complete availability of dicrotophos in foliage and the precise coordination of leaf abscission is highly unlikely but contributes to the conservativeness of the approach.

The general chemical and environmental fate data for dicrotophos li sted in Table 3.2

- 3.3 were used for generating model input parameters for PRZM and EXAMS (listed in Table 3.5 ).

C hemical specific and model input values were chosen in accordance with current divisional guidance (USEPA, 2009).

Table 3.5

. PRZM /EXAMS input parameter values for dicrotophos. Use on cotton and tree injections

PARAMETER (units) VALUE(S) SOURCE COMMENT

Application Rate (kg a.i./ha) Cotton

Emergence = 0.2242

Bloom = 0.5605

Seasonal Max=

1.345

Tree Injection

Single= 0.2556

Seasonal= 0.7668 Cotton

Emergence to pre

- bloom = 0.2 lb

a.i./ A

1 st bloom to 30 days pre

- harvest =

0.5 lb a.i./A with two applications

allowed

Total annual application allowed =

1.2 lb a.i./A

Tree injection

72 inch DBH tree assumed on one acre with 3mL capsules administered.

Two retreatments are assumed.

Number of Applications 3

Interval between Applications (days) 14 Labeled interval for cotton. Assumed interval for tree injection

Molecular weight (g/mol) 237.19

Henry’s Law Constant (atm

m 3 /mol) 3.13 x 10

- 11 Dicrotopho

s RED

Vapor Pressure (torr) 7 x 10

- 5 43500401- Page 31 of 102

- PARAMETER (units) VALUE(S) SOURCE COMMENT

Solubility in Water @ 20 O C, (mg/L or ppm) 11,990 43603202,

43603201

Soil Partition Coefficient (mL/g) K D = 1.24 160828 Lowest non

- sand K D is used because adsorption does not correlate with organic carbon content (An Rf study indicates SD 6167 is likely more mobile than parent dicrotophos [MRID 160829])

CAM (Chemical Application Method) 1 foliar spray; pre

- plant or pre

emergence, unincorporated

Depth of Incorporation (inches) 0

–

Application efficiency (decimal) Cotton

0.95

Tree Injection

1.00 Cotton

Aerial application permitted on label

Tree Injection

No drift

Spray drift fraction (decimal) Cotton

0. 05

Tree Injection

0.00

Application date (day/month) Crop Emergence date as specified by

PRZM scenario and confirmed by OP

cumulative Initial application to cotton can be made from crop emergence to pre

bloom

Hydrolysis Half

- life (days) 72 (parent)

990 (TTR) 160823 SD 6167 and SD228001 are included

in TTR . SD11733 not detected in

study.

Aqueous Photolysis Half

- life @ pH 7 (days) Stable 160824

Aerobic Aquatic Metabolism

Half

- life (days) 16.2 (parent)

17.4 (TTR) SD 228001, SD 6167, and SD 11733

are included in TTR.

TTR included in half

- life estimation.

2X aerobic soil metabolism parameter per Input Parameter

Guidance 1- Page 32 of 102

- PARAMETER (units) VALUE(S) SOURCE COMMENT

Anaerobic Aquatic Metabolism

Half

- life (days) 48 (parent)

Stable (TTR) 160827

SD 228001, SD 6167, and SD 11733

are included in TTR.

Parent a naerobic soil metabolism

half

- life = 8 days. 3X half

- life due to single half

- life value and 2X for estimating an aquatic half

- life with a

soil half

- life per Input Parameter

Guidance 1

.

Aerobic Soil Metabolism Half

life (days) 8.1 (parent)

8.7 (TTR) 160826 Parent only and TTR half

- lives calculated to be approximately the same (2.7 days and 2.9 days, respectively). TTR in this instance includes only SD 6167. Because only one half

- life is available, 3X is used per Input Parameter Guidance 1

1 “Input Parameter Guidance” refers to Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides; Version 2.1, October 22, 2009.



### The modeled aquatic EECs resulting from the dicrotophos uses ( listed in Table 3. 6 ) were used for risk estimation in this screening

- level assessment. The model input and output filenames supporting these values are listed in Appendix A

.

Table 3. 6

. Modeled Aquatic Surface Water 1

- in

- 10

- year EECs for Currently labeled Uses

of Dicrot ophos

Residues Modeled Crop Scenario

(application date) 1

- in

- 10 year

peak daily, μg/L 1

- in

- 10 year,

peak 21

- day

average, μg/L 1

- in

- 10 year,

peak 60

- day

average, μg/L

Total Toxic

Residues MS Cotton 14.19 11.90 7.28

NC Cotton 12.89 10.31 7.71

TX Cotton 16.87 12.26 6.92 FL Citrus (Tree Injection) 8.91 5.80 4.25 Parent Only MS Cotton 13.98 10.40 5.85

NC Cotton 12.43 9.12 6.17

TX Cotton 16.33 10.73 5.54

3.2.2.2 Aquatic Spray Drift Exposure to Dicrotophos- Page 33 of 102

-



### Spray drift exposure to aquatic organisms is also a viable exposure pathway. Concentrations of

0. 6 μg/L in water trigger the Acute Endangered Species LOC (0.05) (based on the Daphnia

magna acute toxicity endpoint of 12.7 ppb). Th e 90 th 

### percentile mean of this concentration is

achieved at distances up to 331 feet from the edge of field according to AgDRIFT v 2.0.10 for aerial applications. This buffer distance would be reduced in the case of non

- listed species. The use of drift reduction technology (DRT) could reduce the distance neces sary for to prevent exceedances of the LOC but DRT is not currently required on dicrotophos labels. Ground applications yielded concentrations as high as 0.6 ppb only up to three feet from the edge of field though all broadcast uses allow aerial applicati ons

.

Spray drift exposure to dicrotophos was determined using the maximum single application rate (0.5 lb a.i./A for subsequent applications to cotton) The distance to water body from edge of field was determined for an initial average concentration of 0.6 ppb in Tier I Ground and Tier I Aerial aquatic assessments. The default ASAE Fine to Medium droplet size distr ibution was assumed.

Exposure from volatility off application site is not addressed due to the low volatility of dicrotophos.

3.2. 3

. Measures of Terrestrial Exposure

3.2.3.1

. Terrestrial Wildlife

Exposure estimates for terrestrial organisms assumed to be in the target area or in an area exposed to off

- site deposition are derived using the T

- REX model (version 1.5.1, 03/22/2012 ). This model incorporates the Kenaga 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 upper bound of residue values from actual field measurements (Hoerger and Kenaga 1972).

The Fletcher et al. (1994) modifications to the Kenaga 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. Based on these data, T

- REX assumes a 35

- day foliar dissipation half

- l ife in the absence of other data.

Terrestrial Exposure from Tree Injection Use Pattern

The dicrotophos tree injection use pattern presents a novel exposure pathway not considered in EFED’s standard exposure models. Tree injections are administered through drilled holes near the base of the tree which allows the pesticide to be conducted thr ough the xylem (tissue for transporting sap) to the branches and leaves of the tree. This distribution results in concentrations in the leaves as much as thirty times higher than other surrounding plant tissues (Mota

- Sanchez, et al. , 2009). A conservativ e estimate of exposure would assume all pesticide is concentrated in the leaves. Martin, et al (1998) derived allometric equations for the estimation of various mass and volume attributes of deciduous tree species. For instance, total foliage of a

red oa k ( Quercus rubra ) can be estimated through the following equation:

Log ( Y ) =
− 2

. 514 + 2

. 326 ∗ log ( DBH )- Page 34 of 102

-



### where Y is the mass of the foliage in kilograms and DBH is the diameter of the tree at breast height in centimeters. Assuming a DBH of 20 inches (50.8 cm), the mass of the foliage is 28 kg or 63 lbs. Dicrotophos tree injections can be applied at a rate of 1 capsule per 2 inches of DBH. A capsule can have as much as three milliliters of formulated product and the formulated product is composed of 8 lbs of active ingredient per gallon. Given this:

20 in

. DBH

1 × 1 capsule

2 in

. DBH × 3 mL

1 capsule × 1 gallon

3785 mL × 8 lbs a

. i

.

1 gallon = 0

. 0634 lbs a

. i

. / tree

Distributing the application of dicrotophos evenly and exclusively to the foliage results in a dose

of 0.001 lb of a.i./lb of foliage or 1,000 ppm.

A less conservative scenario is one in which the dose is evenly distributed throughout the sapwood and foliage. This even distribution may occur at a brief point in the tree injection application but shortly t hereafter the dose would concentrate in its eventual repository, the foliage. Therefore this assumption may not be sufficiently conservative to address exposure to foliage. Sapwood includes the phloem, the facilitator of sucrose, and the xylem, the much larger facilitator of water and other nutrients. The xylem is thought to be the most effective element for conducting tree injection application to the leaves. The mass of the sapwood for the red oak, the same tree used in the calculation above, can be e stimated through the following equation:

Log ( Y ) =
− 4

. 179 + 2

. 495 ∗ log ( DBH )

where Y is the total sapwood volume in cubic meters. Assuming the same DBH of 20 inches and a red oak sapwood density of 740 kg/m 3 

### (Engineering Toolbox, 2012), the sapwood

repr esents 880 kg or 1,942 lbs. Distributing the application of dicrotophos evenly and exclusively, as calculated previously, to the foliage and sapwood results in a dose of 0.0000 3 lb a.i./lb of foliage or 31 ppm.

These estimated concentrations can be compared indirectly to results from a study testing toxicity from exposure to foliage from dic rotophos injected trees (Donley, 1967). In the study, there was 74% to 100% mortality of Daphnia pulex after being exposed to 100 mL distilled water/g foliage. A similar mortality rate was seen when Dapnia magna were exposed to 20 to 30 μg/L dicrotophos (MRID 43787901)

. Given these two studies and assuming similar sensitivity

between the two Daphnia species, a concentration of 2 to 3 ppm may be assumed in the fo liage of the Donley study. This estimate is an order of magnitude lower than the least conservative method for estimating tree injection exposure . Given the uncertainty in extrapolating toxicity across species and the indirect method of determining conce ntration, this is used to characterize the previous estimates as conservative but it also provides some validation for the tree injection

exposure approach as a whole

.- Page 35 of 102

- 

### 3. 2

. 3.2. Terrestrial Plants

No significant effects to terrestrial plants were recorded in guideline plant studies. Therefore terrestrial spray drift modeling was not conducted.

3.3

. Ecological Effects Characterization

In screening

- level ecological risk assessments, effects charac terization describes the types of effects a pesticide can have on aquatic and terrestrial organisms. To date, toxicity tests for amphibian or reptiles are not required; birds are used as surrogates for reptiles and terrestrial

phase amphibians and freshwa ter fish are used as surrogates for aquatic

- phase amphibians. This characterization is based on the registrant

- submitted toxicity data for birds, mammals, fish, invertebrates, and plants for dicrotophos

.

This assessment evaluates the potential for dicrotophos to directly or indirectly affect listed species or modify designated critical habitat. As previously discussed in Section 2.7, assessment endpoints include direct toxic effects on the survival, reproduction, and growth of listed entities,

as w ell as indirect effects, such as reduction of the prey base or modification of habitat. In addition, potential modification of critical habitat is assessed by evaluating effects to the PCEs, which are components of the critical habitat areas that provide essential life cycle needs of listed

entities.

As described in the Agency’s Overview Document (USEPA 2004), the most sensitive endpoint for each taxon is used for risk estimation. For this assessment, evaluated taxa include aquatic

phase amphibians, fr eshwater fish, freshwater invertebrates, aquatic plants, birds (surrogate for

terrestrial

- phase amphibians), mammals, terrestrial invertebrates, and terrestrial plants.

Toxicity endpoints are established based on data generated from guideline studies su bmitted by the registrant, and from open literature studies that meet the criteria for inclusion into the ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA, 2004). Open literature data presented in this assessment were o btained from ECOTOX

information compiled in May 2012 . In order to be included in the ECOTOX database, papers must meet the following minimum criteria:

(1) the toxic effects are related to single chemical exposure; (2) the toxic effects are on an aquatic or terre strial plant or animal species; (3) there is a biological effect on live, whole organisms; (4) a concurrent environmental chemical concentration/dose or application rate is reported; and (5) there is an explicit duration of exposure.

Data that pass the ECOTOX screen are evaluated along with the registrant

- submitted data, and may be incorporated qualitatively or quantitatively into this endangered species assessment. In general, effects data in the open literature that are more conservative than the registrant

submitt ed data are considered. The degree to which open literature data are quantitatively or qualitatively characterized is dependent on whether the information is relevant to the assessment- Page 36 of 102

-



### endpoints (survival, reproduction, and growth) identified in Section 2 .8. For example, endpoints such as behavior modifications are likely to be qualitatively evaluated, because quantitative relationships between modifications and reduction in species survival, reproduction, and/or growth are not available.

In addition t o registrant

- submitted and open literature toxicity information, other sources of information, including use of the acute probit dose

- response relationship to establish the probability of an individual effect and reviews of the Ecological Incident Informat ion System (EIIS), are conducted to further refine the characterization of potential ecological effects associated with exposure to dicrotophos . A summary of the available aquatic and terrestrial ecotoxicity information, use of the probit dose

- response re lationship, and the incident

information for dicrotophos are provided in Sections 4.1 through 4.4, respectively

.

Toxicity d ata are available for monocrotophos , a pesticidal active ingredient (PC code: 058901) that was registered for use in the United States until its cancellation in 1991

. Monocrotophos is a highly toxic metabolite (golden eagle LD 50 

### = 0.2 mg/kg

- bw) that can be formed by demethylation of dicrotophos. Laboratory studies on the degradation of dicrotophos do not indicate that monocrotoph os forms in soil or water in any significant quantities. However, monocrotophos may be a significant metabolite in plants ( MRID s 44731001 and 13505) . The amount of monocrotophos that can form from dicrotophos and the rate of formation and decline

in and/ or on foliage soon after application is an uncertainty

.

No toxicity data were available on dicrotophos mixtures with other pesticides. Two multi

- a

. i

. product s are registered for dicrotophos

, Bidrin XP and Bidrin XP II. Bidrin XP contains 4 pounds of 82% a.i. dicrotophos and 1 pound of 25 .1 % a.i. bifenthrin per gallon

. Bidrin XP II contains 4 pounds of 43.1% a.i. dicrotophos and 1 pound of 10.8 % a.i. bifenthrin per gallon.

3.3.1. Aquatic Toxicity Assessment

The most sensitive acute and chronic effects measurement endpoints associated with dicrotophos exposure to freshwater and estuarine/marine species are summarized in Table 3.11. All acceptable and supplemental studies available for dicrotophos are describe d below

.

Results of acute toxicity studies of freshwater and estuarine/marine organisms indicate that dicrotophos is slightly to moderately toxic to fish and very highly toxic to aquatic invertebrates on an acute exposure basis. Statistically significant reductions in growth ( i.e. , length and weight) were seen in aquatic invertebrates chronically exposed to dicrotophos.- Page 37 of 102

-



### Table 3.11. Most Sensitive Acute and Chronic Toxicity Data for Aquatic Organisms Exposed to Dicrotophos

. Exposure

Scenario Species A ffected Endpoint Toxicity Measurement MRID (Classification)

Freshwater Fish

Acute Rainbow trout

( Oncorhynchus mykiss ) Mortality 96

- hr LC 50 = 5.7 m g a.i./L Slope: N/A MRID 40098001 ( Supplemental )

Chronic Fathead minnow

( Pimephales promelas ) Mortality NOAEC = 9.88 m g a.i./L MRID 48482901 ( Supplemental )



### Freshwater Invertebrates

Acute Water flea

( Daphnia magna ) Immobility 48 hr EC 50 0.0126 m g a.i./L Slope: N/A MRID 43787901 (Acceptable)

Chronic Water flea

( Daphnia magna ) Length 21

- day NOAEC = 0.0017 mg a.i./L

LOAEC = 0.0028 mg a.i./L MRID 44956501 (Supplemental)



### Estuarine/Marine Fish

Acute Sheepshead

minnow ( Cyprinodon variegatus ) Mortality 96

- hr LC 50 8 3.8 m g a.i./L Slope: N/A MRID 43603306 (Acceptable)

Chronic No studies available



### Estuarine/Marine Invertebrates

Acute Mysid shrimp

(Americamysis

bahia ) Mortality 96

- hr EC 50 = 0.07 7 m g a.i./L Slope: NA MRID 4 3603305 (Acceptable)

Chronic Mysid shrimp

(Americamysis

bahia ) ♂+♀ length,

♀ weight 21

- day NOAEC= 0. 00 309 mg ai/L MRID 43893 901 ( Acceptable)



### Aquatic Plants

7

- day

exposure Duckweed

( Lemna gibba ) None 7

- day EC 50 >117 m g a.i./L

NOAEC = 117 m g a.i./L MRID 48443703 ( Acceptable )

96

- hour

exposure M arine alga

( Skeletonema

costatum ) Cell density,

biomass, and growth rate 96

- hr EC 50 >118 m g a.i./L

NOAEC = 14.3 m g a.i./L MRID 48443701 ( Acceptable )



### 3.3.1.1 Toxicity to Freshwater Fish

Acute Effects

TGAI

A 96

- h our static acute exposure study ( MRID 40098001, Supplemental ) with fingerling ( mean= one gram) rainbow trout ( Onchorhynchus mykiss ) is available for dicrotophos

. T en trout were exposed to nominal concentration s of 0 (negative control)

, 4.2, 6.5, 10, 16, and 24 mg/L

. Loading did not exceed 0.8 g/L. The 96

- hour LC 50 

### was 6.3 mg /L ( 5.7 mg a.i. /L corrected for 90% purity).

A 96

- hour static acute exposure study ( MRID 40098001, Supplemental ) with juvenile (mean= one gram) bluegill sunfish ( Lepomis macrochirus ) is available for dicrotophos

. At least ten fish were exposed to each treatment concentration, and at least six concentrations were tested ( study- Page 38 of 102

-



### design information was generically summarized by this report and no greater detail was available

on a chemical

- by

- chemical basis) (USFWS, 1980) . The 96

- hour LC 50 

### was 24.2 mg /L ( 19.4 mg a.i./L corrected for 80% purity)

.

A 96

- hour static acute exposure study ( MRID 40098001, Supplemental ) with juvenile (mean= 1.4 grams) channel catfish ( Ictalurus punctatus ) is available for dicrotophos. T en fish were exposed to nominal concentrations of 0, 65, 100, 160, 240, and 370 mg/L . The 96

- hour LC 5 0



### was 7 7 mg /L ( 6 9 mg a.i./L corrected for 90% purity).

Chronic Effects

A 33

- d ay fish early life stage (ELS) study (MRID 48482901 ; Supplemental ) with fathead minnow ( Pimephales promelas ) is available for dicrotophos ( 87.7 % a.i. ) . The fathead minnow eggs used for the initiation of the definitive test were obtained from an in

- house culture. Fertilized eggs/embryos (80/level, <24 hours old) were exposed to Dicrotophos Technical at nominal concentrations of 0 (negative control), 0.33, 0.65, 1.3, 2.5, 5 .0, and 10 mg ai/L. Mean

measured concentrations were <0.174 (<MQL, control), 0.327, 0.590, 1.21, 2.45, 4.94, and 9.88 mg ai/L, respectively. Minnows in two replicates of the control were redistributed following an inadvertent pooling event. Sublethal e ffects of edema and lying on the bottom were observed to varying degrees in the control and four treatment levels

. No statistically or biologically significant effects on egg hatchability, larval survival, length, or wet weight were determined at

any conc entration tested and a NOAEC of 9.88 mg a.i./L is used in this assessment

.

3.3.1.2. Toxicity to Freshwater Invertebrates

Acute Effects

TGAI

A 48

- h our flow

- through acute exposure study (MRID 43787901 ; Acceptable) with Daphnia

magna is available for dicrotophos . Twenty daphnids per level were exposed to mean

- measured

concentrations of <0.77 (control and DMF control), 0.002 09, 0.003 40, 0.004 88, 0.008 72, 0.014 9,

and 0.027 3 m g ai/L

. The LC 50 

### was 0.012 6 m g ai/L; 10% mortality occurred in the lowest

trea tment and the NOAEC could not be determined ( < 0.002 09 m g ai/L )

.

Chronic Effects

A 21

- day chronic flow

- through toxicity study (MRID 44956501, Supplemental) of dicrotophos

with Daphnia magna was submitted. Daphnids were cultured in house, and were < 24 hours old

at the start of the test. Four replicates (40 daphnids per level, 10 daphnids per replicate) were

maintained for each treatment level. Mean

- mea sured exposure concentrations were <0.1 (<MQL, control and DMF control ), 0. 000 35, 0. 000 59, 0. 000 99

, 0.001 7, 0.002 8, and 0.0044 m g ai/L

. DMF solvent concentrations did not excee d 5 μL /L. The NOAEC and LOAEC were

determined to be 0. 0017 m g ai/L and 0.0028 m g ai/L based on reductions in mean total length

. No sublethal effects were reported.

3.3.1.3. Toxicit y to Estuarine/Marine Fish- Page 39 of 102

-



### Acute Effects

A 96

- h our static acute study (MRID 43603306 ; Acceptable ) tested the acute toxicity of dicrotophos technical (87.65% a.i.) to sheepshead minnow ( Cyprinodon variegatus ). Fish were exposed to mean

- measured c oncentrations of 0 (control), 11.8

, 21.7

, 36.1

, 62.7 , and 102 mg ai/L

. 20 fish per test concentration were exposed

. M ortalities and/ or sublethal effects were observed

at all test concentrations . T he 96

- hour LC 50 

### is 83.8 mg ai/L

. Dicrotophos is classified a s slightly toxic to sheepshead minnow on an acute exposure basis.

Chronic Effects

No chronic estuarine/marine fish toxicity tests with TGAI or formulations of dicrotophos

were submitted.

3.3.1.4. Toxicity to Estuarine/Marine Invertebrates

Acute Effects

A 96

- h our flow

- through acute exposure study (MRID 43603305 ; Acceptable) with mysid shrimp ( Americamysis bahia ) is available for dicrotophos . Twenty mysids per level were exposed to

mean

- measured concentrations of 0 ( nominal; control and triethylene glycol control), 0.020, 0.035, 0.060

, 0.115, and 0.184 mg ai/L. Triethylene glycol solvent concentrations did not exceed 0.0016 mL/L. Sublethal effects of lethargic and/or erratic behavior were recorded in the three highest treatme nt levels . The 96

- hr EC 50 

### is 0.0 7 7 mg ai/L; the NOAEC is 0.035 mg ai/L based

on erratic behavior at 0. 0 60 mg ai/L

. Dicrotophos is classified as very highly toxic to mysids on an acute exposure basis.

A 96

- hour flow

- through acute shell deposition study (MRID 43739801; Acceptable) with Eastern oyster ( Crassostrea virginica ), is available for dicrotophos. Twenty oysters per level were exposed to m ean

- measured concentrations of <0.47 (control), 15.3, 25.9, 40.6, 70.7, and

125 mg ai/L. Shell growth in all treatments was less than that of the control, with growth inhibition ranging between 12 and 21 percent. A monotonic dose

- response was observed through the second highest treatment ( i.e. , 70.7 mg ai/L). The EC 50 

### is considered to be greater than 125 mg ai/ L, the highest concentration tested.

Chronic Effects

A 28

- day chronic exposure toxicity with mysids (MRID 43893901 ; Acceptable ) is available for dicrotophos . Conducted under flow

- through c onditions, neonates less than 24 hours old were exposed to mean

- m easured concentrations of < 0.00 118 (<LOQ, control and triethylene glycol

control ), 0.00 309, 0.00 615, 0.0 108, 0.0 223 , and 0.0 454 m g ai/L

. Female body length and dry weight were the most sensitive endpoints assessed, with NOAEC and LOAEC values of 0.00 309

and 0.00 615 m g ai/L, respectively.

3.3.1.5. Toxicity to Aquatic Plants- Page 40 of 102

-



### Studies were submitted for a freshwater vascular plant (duckweed, Lemna gibba ) and two phytoplanktonic nonvascular plants: a green algae ( Pseudokirchneriella subcapitata ) and a

diatom ( Skeletonema costatum ).

Vascular Aquatic Plants

A study (MRID 48443703 ; Acceptable 

### ) examining the effect of technical dicrotophos on the aquatic macrophyte duckweed was submitted. Three replicates were exposed to dicrotophos

mean

- measured conce ntrations of <LOQ (<1.99, control), 7.32, 14.8, 29.4, 59.2, and 117 mg

ai/L

. F rond numbers, dry weight, and growth rate all were promoted in the treatments as compared to the control, resulting in a non

- definitive 7

- day EC 50 

### of > 117 m g a.i./L and a NOAEC of 117 μg a.i./L. Chlorosis of fronds was noted in treatments exposed to dicrotophos concentrations greater than 14.8 mg ai/L.

Nonvascular Aquatic Plants

A study (MRID 48443702 ; Acceptable 

### ) examining the effect of technical dicrotophos on green al gae ( Pseudokirchneriella subcapitata ) was submitted

. Six control replicates and 3 replicates per treatment level were exposed to mean

- measured concentrations of <LOQ (<1.99, control), 3.78, 7.36, 14.6, 29.1, 58.6 and 118 mg ai/L

. Maximum inhibitions of 25% ( 118 mg ai/L ; cell density and yield) were recorded, and the 96

- hour EC 50 

### is > 118 mg ai/L. The NOAEC was statistically determined to be 29.1 m g ai/L.

A study (MRID 48443701 ; Acceptable 

### ) examining the effect of technical dicrotophos on Skeletonema co statum was submitted. Three replicates were exposed to dicrotophos mean

measured concentrations of <LOQ (<1.99, control), 3.63, 7.21, 14.3, 28.4, 58.2 and 118 mg ai/L

. Maximum inhibitions of 34 and 36% ( 118 mg ai/L ; cell density and yield, respectively) were recorded, and the 96

- hour EC 50 

### is > 118 mg ai/L. The NOAEC was statistically determined to be

14.3 m g ai/L.

3.3.2 Terrestrial Effects Characterization

The most sensitive acute and chronic toxicity reference values associated with dicrotophos exposure to mammals, birds, and terrestrial invertebrates are summarized in Table 3.12 . The most sensitive measurement endpoints for terrestrial plants are presented in Table 3. 1 3

.

Dicrotophos is very highly toxic to Norway rat ( Rattus norvegicus ) on an acute exposure basis.

A three

- generation study on reproduction in the rat showed dicrotophos to cause chronic toxicity

effects and impact s on pup survival

.

An acute oral (dose

- based) toxicity study with the domestic goose (Toulouse strain) indic ated

that dicrotophos is very highly toxic to the domestic goose when administered a s a single oral

dose. P asserine s (i.e., house finch and house sparrow) did not exhibit heightened sensitivity to dicrotophos , although dicrotophos retains its very highly toxic classification for these species

.- Page 41 of 102

-



### S ubacute dietary toxicity studies indicate that dicrotophos technical is also very highly toxic to bobwhite quail ( Colinus virginianus ) and Japanese quail ( Coturnix japonica ) , and highly toxic to

the mallard (

Anas platyrhynchos ) on a subacute dietary exposure basis. T reatment

- related

effects on both adult and offspring endpoints were reported in avian reproduction studies

conducted with bobwhite quail and mallard . No studies evaluating toxicity of dicrotophos

form ulations were submitted

.

Results of available toxicity studies indicate that technical grade dicrotophos is highly toxic to honey bees (

Apis mellifera ) on an acute contact exposure basis.

T errestrial plants did not exhibit phytotoxic response to applications (made at the maximum label

rate ) of dicrotophos during Tier I seedling emergence and vegetative vigor testing

.

Table 3.12. Dicrotophos Toxicity Measurement Endpoints for Terrestrial Animals.
Exposure

Scenario Species Exposure

Duration Toxicity Reference Value MRID (Classification)

Mammals

Acute (Dose

- based) Laboratory rat

( Rattus norvegicus ) Single oral dose LD 50 11 .0 mg /kg bw (male)

LD 50 8.0 mg /kg bw (female) Acc. Nos. 261098

&

43893901

Chronic (Dietary

- based) Laboratory rat

( Rattus norvegicus ) Three

generation NOAEL = 2.0 mg/kg diet

LOAEL = 5.0 mg/kg diet

Endpoints based on decreased

pup survival Acc. No

. 00013446 (Supplemental)



### Birds

Acute (Dose

- based) Domestic

goose ( Anser

anser ) 14

- day single

oral dose LD 50 : 1.22 mg /kg bw MRID 00013439 (Supplemental)

House

sparrow ( Passer

domesticus ) Single oral

dose LD 50 : 3 mg/kg bw Acc. No. 00160000 ( Supplemental)

Acute (Dietary

- based) Bobwhite

quail ( Colinus virginianus ) 7

- day dietary LC 50 : 13 mg /kg diet MRID s 00013707 &

00063392 ( Supplemental )

Mallard duck ( Anas platyrhynchos ) 8

- day dietary LC 50 : 94 mg/kg diet MRID 00022923 ( Supplemental )

Chronic (Dietary

- based) Mallard duck

Anas platyrhynchos ca. 20 week

avian reproduction study LOAEC: 3.0 mg ai/kg diet

NOAEC: 1.0 mg ai/kg diet (based on female weight at study termination) MRID 44005501 (Acceptable)

Bobwhite quail

Colinus virginianus ca. 20 week

avian reproduction study LOAEC: 1.5 mg ai/kg diet

NOAEC: 0.5 mg ai/kg diet (based on eggs laid) MRID 44005502 (Acceptable)



### Terrestrial Invertebrates- Page 42 of 102

-



### Table 3.12. Dicrotophos Toxicity Measurement Endpoints for Terrestrial Animals.
Exposure

Scenario Species Exposure

Duration Toxicity Reference Value MRID (Classification)

Acute (Contact) Honeybee 48

- hour LD 50 0.076 μg a.i./bee MRID s 05004151 &

05001991 (Acceptable)



### Table 3.13

. Dicrotophos Toxicity Measurement Endpoints for Terrestrial Plants.
Exposure

Scenario Taxon Toxicity Reference Value Reference (Classification)

Seedling Emergence (Tier I) Monocot EC 25 > 1.0 lb a.i./A

NOAEC = 1.0 lb a.i./A MRID 48482902 ( Supplemental )

Dicot EC 25 > 1.0 lb a.i./A

NOAEC = 1.0 lb a.i./A Vegetative Vigor (Tier I) Monocot EC 25 > 0.95 lb a.i./A

NOAEC = 0.95 lb a.i./A MRID 48482903 ( Acceptable )

Dicot EC 25 > 0.95 lb a.i./A

NOAEC = 0.95 lb a.i./A



### In addition to the standard suite of laboratory toxicity studies, two field studies are available for dicrotophos applied to cotton. Conducted in Alabama (MRID 40917001 , Supplemental ) and Arizona (MRID 40873701 , Supplemental ), these field studies evaluated effects to wildlife across fourteen replicate fields (eight treated and six control)

. In Alabama, two applications of 0.5 lb ai/A were made at a six day interval. In Arizona, three applications of 0.2 lb ai/A were separated by seven day interval s

. Study results are potentially confounded by tank mixing of other insecticide active ingredients with dic rotophos. However, b oth studies identified treatment

related mortalities , and residue analysis accompanied those determinations

. In Alabama, external and internal dicrotophos residues were detected on indigo buntings as high as 17 ppm and 0.51 ppm, repec tively. Further, b oth study reports include extensive lists of avian, mammalian, and hepetofaunal species documented in or around the treated fields. While neither study design is sufficiently robust for quantitative use in risk estimation, a necdotal inf ormation contained within the study reports is useful for risk characterization.

3.3.2.1. Toxicity to Mammals

Acute Effects

The acute oral toxicity endpoint ( LD 50 

### ), based on Norway rat ( Rattus norvegicus )

, is 11 mg /kg

bw for males and 8.0 mg/kg

- bw for females as reported by the Health Effects Division (HED) ( MRIDs 261098 and 43893901 ; USEPA 200 6 ).

Chronic Effects- Page 43 of 102

-



### A three

- generation rat reproduction study reviewed by HED resulted in a NOAEL of 2 mg /kg

diet based on pup survival (Acc. 000 13446). M ammalian reproduction was adversely affected at dicrotophos concentrations of 5 ppm and greater.

3.3.2.2. Toxicity to Birds

Acute and Subacute Dietary

Acute

Multiple avian acute toxicity studies are available for d icr otophos

. In one a vian acute toxicity
study ( Acc. No. 00013439; Supplemental) , four domestic geese ( Toulouse strain ) per treatment

group were exposed to technical (99% a.i.) dicrotophos and monitored for 14 days . Nominal

concentrations of 0.0385, 0.385, 3.85, and 38.5 mg/kg

- bw were delivered by stomach tube to
geese ranging in weight from 2.96 to 4.50 kg. The diet during the observation period was shelled
corn. The two lower treatment levels had no mortality after 14 days, whereas the two upper

treatmen t levels had total mortality after 2 hours. The LD 50 

### was determined to be 1.22 mg/kg

bw.

Another avian acute toxicity study ( Acc. No. 00160000 ; Supplemental) is available for
dicrotophos

. 12 male California quail ( Callipepla californica )

, 18 months of a ge, were exposed

to dicrotophos technical (80% a.i .)

. The LD 50 

### was determined to be 1.89 mg/kg

- bw ( 1.51 mg/kg

b w when adjusted for purity)

.

Avian acute toxicity studies testing passerines are also available ( Acc. No. 00160000 ; Supplemental) . 16 male house sparrows ( Passer domesticus ) were exposed to technical
dicrotophos (98% α isomer), and the LD 50 

### w as reported to be 3 mg/kg

- bw. Eight pairs of male

and female house finches ( Carpodacus mexicanus ) were exposed to technical dicrotophos (98%

α isomer), and the LD 50 

### was reported to be 2.83 mg/kg

- bw. Neither sparrow nor finch ages were

available. The study reports do not clarify whether the number s of bobwhite, sparrows, or
finches represent totals per treatment level or totals per test.

Subacute

An a vian subacute dietary toxicity study (MRID 000 13707 ; Supplemental ) is available for
dicrotophos . Bobwhite quail, 4

- 7 days old, were exposed to technical dicrotophos at levels of 1,
3, 9, 27, and 610 mg /kg

- diet for a period of four weeks . The dietary LC 50 

### was 13 mg/kg

- diet.

A second avian subacute dietary toxicity study ( Acc. No. 00022923 ; Supplemental ) is available

for dicrotophos

. Five day old Mallard duck s ( Anas platyrhynchos ) were exposed to dicrotophos

at eight different treatment concentrations; 1 0 birds per level ; and the dietary LC 50 

### was determined to be 94 mg/kg

- diet

. Ten day old Mallard duck s ( Anas platyrhynchos ) were also- Page 44 of 102

-



### exposed to dicrotophos but only five treatment concentrations were used; 10 birds per level ; and

the dietary LC 50 

### was determined to be 144 mg/ kg

- diet. Dicrotophos is classified as highly to

toxic very highly toxic to birds on a subacute dietary basis.

Chronic

A one

- generation reproductive toxicity study (MRID 44005501 ; Acceptable) is available for dicrotophos

. Toxicity of chronic exposure to 6 replicate pens (2 males + 5 females) per level of

16

- month old mallard (

Anas platyrhynchos ) was assessed over ca. 20 weeks. Dicrotophos was administered to the birds mixed in the diet at nominal concentrations of 0 , 1, 3 , and 10 mg/kg

. This study determined a NOAEC of 1 ppm, since significant reductions (ca. 8%) in f emale bodyweight were recorded at the 3 ppm level (the LOAEC)

. At 10 ppm, significant effects to mallard reproduction included egg production, embryo viabil ity, hatchling production and

survival , adult bodyweight, and thickness of eggshells.

A second one

- generation reproductive toxicity study (MRID 44005502 ; Acceptable) is available

for dicrotophos

. Toxici ty of chronic exposure to 20 pairs per level of 16

- month old northern bobwhite quail ( Colinus virginianus ) was assessed over ca. 20 weeks. Dicrotophos was administered to the birds mixed in the diet at nominal concentrations of 0 , 0.5

, 1.5 , an d 5 mg/kg

. Egg production and female body weight were signi ficantly affected at the 1.5 ppm level , reduced by 25% and 9%, respectively . At 5 ppm, embryo viability, the number of 14

- day old survivors, adult body weight, and adult mortality were significantly different from the control group. The

NOAEC of this stu dy is 0.5 mg/kg

- diet; the LOAEC is 1.5 mg/kg

- diet.

3.3.2.3. Toxicity to Terrestrial Invertebrates

Acute Effects

A 24

- h our acute contact study ( MRID s 05004151 and 05001991 ; Acceptable) with honey bees ( Apis mellifera ) is available for dicrotophos

. Two replicates of 10 bees were exposed to each of five or six concentrations of technical dicrotophos (study report generic for the testing of numerous chemicals; no further details pertaining to dicrotophos testing were available) . This study reported

an acu te oral LD 50 

### of 0.0 6 8 μg ai/bee

, and an acute contact LD 50 

### of 0.076 μg ai/bee. Dicrotophos

is classified as highly toxic to honey bees on an acute dermal exposure basis.

Further, residues on foliage have been found to remain toxic to bees an d other benef icial insects for as many as 16 days (MRIDs 05009353 and 05013577). In MRID 05013577 (Clinch, P.G., and

T. Palmer

- Jones, 1971) , dicrotophos (85% EC ) was applied as a pre

- blossom spray to raspberries

at a rate of 0.43 lb a.i./A six days before bloom. Hives were located near the treated area and bee mortalities were recorded through 16 days after application. By day 21, residual toxic effects of the spray application had subsided. In MRID 05009353 (Clinch, P.G., et al., 1973), dicrotophos (85% EC) was applied to flowering white clover at a rate of 0.45 lb a.i./A ; h oney bee mortality exceeding 50% was recorded for five days following application in the treated area.

3.3.2.4. Toxicity to Terrestrial Plants- Page 45 of 102

-



### The effect of Bidrin 8 Water Miscible Insecticide ( TEP; 83.8% dicrotophos ) on the Tier I seedling

emergence ( MRID 48482902, Supplemental ) of monocot (corn, Zea mays ; onion, Allium cepa ;

ryegrass, Lolium perenne ; and oat, Avena sativa ) and dicot (radish, Raphanus sativ us ; cucumber

, Cucumis sativus ; lettuce, Lactuca sativa ; Sugarbeet, Beta vulgaris ; soybean, Glycine max ; and

tomato, Lycopersicon esculentum ) crops was studied at nominal concentrations of 0 (negative

control ) and 1 lb a.i./A. None of the monocot or dicot species were significantly af fected at the maximum labeled rate, resulting in overall nominal NOAEC and EC 25 

### values of 1.0 and >1.0 lb ai/A, respectively.

The effect of Bidrin 8 Water Miscible Insecticide ( TEP; 83.8% dicrotophos) on the Tier I vegetative vigor ( MRID 48482903, Acceptable ) of monocot (corn, Zea mays ; onion, Allium cepa ;

ryegrass, Lolium perenne ; and oat, Avena sativa ) and dicot (radish, Raphanus sativ us ; cucumber,

Cucumis sativus ; lettuce, Lactuca sativa ; Sugarbeet, Beta vulgaris ; soybean, Glycine max ; and

tomato

, Lycopersicon esculentum ) crops was studied at mean

- measured concentrations of <MQL (<0.0007 lb a.i./A, negative control), and 0.95 lb a

. i

. /A

. None of the monocot and dicot species were affected at the maximum labeled rate, resulting in overall mean

- meas ured NOAEC and EC 25 

### values of 0.95 and >0.95 lb ai/A, respectively.

3.4. ECOTOX Open Literature

A literature search in the Agency’s ECOTOX database ( May 2012 ) resulted in one paper that passed the ECOTOX and OPP acceptability screens and reported an endpoint more sensitive than those resulting from the submitted guideline studies. Meyers, S.M.

, 1990 , reported a 5

- day

LC 50 

### for bobwhite quail of <12.5 mg/kg

, although the lowest concentration tested, 20 ppm, adds uncertainty to the reliability of the r eported LC 50 

### , which is less than 20 ppm . This paper has

been received and a formal Open Literature Review Summary evaluation is being conducted ; t he

review will be available for the final version of this risk assessment. For the time being, the endpoint will be use d provisionally and qualitatively, pending review.

A study (Moser, V.C., 2011) examining a ge

- related differences in acute neurotoxicity in the Norway rat ( Rattus norvegicus ) provides information useful for m ammalian risk characterization; howev er, the reported en d points are based on sublethal effects rather than mortality and will not be used as a quantitative measure of dicrotophos hazard

.

The database also contains a number of studies that evaluated the effect of dicrotophos on target
insects , though none of the studies result in more sensitive endpoints and are generally not endpoints used in Agency risk assessments.

4. Risk Characterization

4.1. Risk Estimation

Toxicity data and exposure estimates are used to evaluate the potential for adv erse ecological

effects on non

- target species. This assessment for dicrotophos relies on the deterministic RQ method to provide a metric of potential risks. The RQ provides a comparison of exposure estimates to toxicity endpoints ( i.e. , the estimated exp osure concentrations are divided by acute- Page 46 of 102

-



### and chronic toxicity values). The resulting unitless RQs are compared to the Agency’s LOCs, as

shown in Table 2.3 . LOCs are used by the Agency to indicate when the use of a pesticide, as directed by the label, ha s the potential to cause adverse effects to non

- target organisms.

4.1.1. Aquatic Organisms

The highest screening

- level aquatic parent only EECs based on the maximum application rates for each proposed use pattern were used to derive RQs. These exposure estimates represent concentrations in surface water ( Table 3.7 ). Peak EECs are used to represent acute exposure to fish, aquatic invertebra tes and aquatic plants, and 21

- day and 60

- day average EECs represent chronic exposure to aquatic inverte brates and fish, respectively. Total toxic residue RQs are derived for characterization purposes, however, risk conclusions remain the same for all taxa regardless of whether parent only or TTR are considered for risk estimation.

4.1.1.1. Fish and Invertebrates

Fish

Table 4.1 lists acute RQs calculated for fish (freshwater and estuarine/marine) and aquatic

- phase amphibians exposed to dicrotophos , based on the peak EECs generated from PRZM/EXAMS modeling scenarios. Results of acute toxicity studies in freshwater and estuarine/marine fish ( Table 3.13 ) indicate that dicrotophos is “ moderately toxic” to fish on an acute exposure basis. However, RQs for uses of dicrotophos fall below the Agency’s acute risk to listed species LOC (0.05), as well as the Agency’s acute risk to non

- listed species LOC of 0.5.

Table 4.1. Acute Risk Quotients for Fish and Aquatic

- phase Amphibians Exposed to Dicrotophos at the Upper

- bound EECs Using the Most Sensitive of the Available Endpoints.

PRZM Scenario (standard unless noted) 1

- in

- 10 year peak daily, μg/L RQ

Freshwater LC 50 5,700 μg ai/L Estuarine/Marine

LC 50 83,800 μg ai/L

Total Toxic Residues

TX Cotton 16.87 0.003 0 < 0.00 1

Parent only

TX Cotton 16.33 0.00 29 < 0.00 1

1 Acute risk to non

- listed species LOC for aquatic fish is 0.5

2 Acute risk to listed species LOC for aquatic fish is 0.05



### Chronic exposure RQs for fish were calculated with the endpoint derived from the guideline ELS study (Table 4. 2 )

. RQs for all scenarios fall below the Agency’s chronic risk LOC ( 1.0 )

.

Table 4. 2

. Chronic Risk Quotients for Fish and Aquatic

- phase Amphibians Exposed to Dicrotophos at the Upper

- bound EECs Using the Most Sensitive of the Available Endpoints.- Page 47 of 102

-

PRZM Scenario (standard unless noted) 1

- in

- 10 year 60

- day average, μg/L RQ

NOAEC: 9,880 μ g ai/L

Total Toxic Residues

NC Cotton 7.71 <0.001

Parent only

NC Cotton 6.17 < 0.001

1 Chronic risk to listed and nonlisted aquatic animals is 1.0



### Aquatic Invertebrates

Based on the available acute studies, dicrotophos is categorized as very highly toxic to Daphnia

magna on an acute exposure basis

. RQs for freshwater invertebrates exceed the acute risk LOC

for listed species under every scenario modeled

.

Mysids are much less acutely sensitive to dicrotophos than daphnids, although dicrotophos is still

classified as very highly toxic to mysid shrimp. Estuarine/marine invertebrate R Qs exceed the

acute ri sk LOC for listed species for all model ed scenarios ( Table 4.3 )

.

Table 4.3. Acute Risk Quotients for Aquatic Invertebrates Exposed to Dicrotophos at the Upper

- bound EECs Using the Most Sensitive of the Available Endpoints.

PRZM Scenario (standard unless noted) 1

- in

- 10 year peak daily, μg/L RQ

FW LC 50 12.7 μg ai/L E/M LC 50 77 μg ai/L

Total Toxic Residues

TX Cotton 16.87 1. 33 0.2 2

Parent only

TX Cotton 16.33 1. 29 0.2 1

1 Acute risk to non

- listed species LOC for aquatic animals is 0.5

2 Acute risk to listed species LOC for aquatic animals is 0.05



### Aquatic invertebrates exhibit sensitivity to dicrotophos in studies over chronic exposure

durations. The chronic LOC (1.0) is exceeded for freshwater and estuarine/marine inver tebrates

for all PRZM scenario s modeled ( Table 4.4 )

.

Table 4.4 . Chronic Risk Quotients for Aquatic Invertebrates Exposed to Dicrotophos at the Upper

- bound EECs Using the Most Sensitive of the Available Endpoints.

PRZM Scenario (standard unless noted) 1

- in

- 10 year 21

- day average, μg/L RQ

FW NOAEC : 1.7 μ g ai/L E/M NOAEC :

3.09 μ g ai/L

Total Toxic Residues

TX Cotton 12.26 7.2 3.97

Parent only- Page 48 of 102

- TX Cotton 10.73 6.3 3.47

1 Chronic risk to listed and nonlisted aquatic animals is 1.0



### 4.1.1.2. Aquatic Plants

Exposure modeling data indicate that environmentally relevant concentrations of dicrotophos are orders of magnitude below levels which could potentially result in adverse effects to aquatic plant communities

. Thus t here is insufficient exp osure for either the nonlisted or listed species LOC (1.0) to be exceeded ( Table 4.5 )

.

Table 4. 5 . Acute Risk Quotients for Aquatic Vascular and Nonvascular Plants Exposed to Dicrotophos at the Upper

- bound EECs Using the Most Sensitive of the Available Endpoints.

PRZM Scenario (standard unless noted) 1

- in

- 10

year peak daily, μg/L Aquatic Vascular Plant RQs Nonvascular Plant RQs

EC 50 μg ai/L

Nonlisted

> 117 ,000 NOAEC

μg ai/L

Listed 117,000 EC 50

μg ai/L

Nonlisted > 118,000 NOAEC

μg ai/L

Listed 14,300

Total Toxic Residues

TX Cotton 16.87 < 0.001 < 0.001 < 0.001 < 0.01

Parent Only

TX Cotton

16.33 < 0.001 < 0.001 < 0.001 < 0.01

1 Plant LOC is 1.0. Bold indicates exceeds LOC



### 4.1.2. Terrestrial Organisms

4.1.2.1. Mammals

Based on the available acute toxicity data, the LD 50 

### for dicrotophos is 11 mg/kg for male rats, and 8 mg/kg for female rat s, respectively. Therefore, dicrotophos is categorized as “ very highly

toxic ” to mammals on an acute exposure basis

. RQs exceed the acute non

- listed species LOC (0.5) by a factor of up to 23 X (short grass). Table 4.6 lists maximum acute EECs and RQs for all of the proposed use rates based on the upper 90th percentile Kenaga values. The acute listed species LOC is 0.1. With an RQ of 0.07 , o nly t he large mammal granivore forage class does not

result in an LOC exceedanc e

. Further discussion of the predicted exposure values relative to the levels at which mortality was observed is provided as part of the risk description in Section

4.2.4

.

Based on the proposed maximum application rates on cotton

, there are chronic dose

- based exposure concerns for mammals of all size class es for the short grass, tall grass

, broadleaf plant

, fruits/pods, arthropods, and and granivore sub

- classes . RQs exc eed the LOC by a factor of up to
915 X ( short grass )

. Table 4. 7 lists maximum chronic dose

- based EECs and RQs based on the- Page 49 of 102

-



### upper 90 th 

### percentile Kenaga values for applications to cotton

. Additionally, there are

exceedances for chronic dietary

- based exposure for all forage types assessed ( Table 4. 8 ).- Page 50 of 102

-



### Table 4.6. Mammalian Acute Dose

- based RQs for the Use of Dicrotophos on Cotton. Bold indicates exceedance of the LOC.

Rate (# apps; interval) Size

Class (grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 0.5 (2; 14d) 15 17.58 201.1 11.4 92.18 5.2 113.1 6.4 12.57 0.71 78.77 4.5 2.79 0.16

35 14.23 139.0 9.8 63.71 4.5 78.2 5.5 8.69 0.61 54.44 3.8 1.93 0.14

1000 6.15 32.2 5.2 14.77 2.4 18.1 3.0 2.01 0.33 12.62 2.1 0.45 0.073

Acute risk to non

- listed species LOC for mammals is 0. 5 Acute risk to listed species LOC for mammals is 0. 1



### Table 4.7

. Mammalian Chronic Dose

- based RQs for the Use of Dicrotophos on Cotton

. Bold indicates exceedance of the LOC.

Rate (# apps; interval) Size

Class (grams) Adjusted

NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 0.5 (2; 14d) 15 0.22 201.12 915.08 92.18 419.41 113.13 514.73 12.57 57.19 78.77 358.40 2.79 12.71

35 0.18 1 39.00 781.65 63.71 358.26 78.19 439.68 8.69 48.85 54.44 306.15 1.93 10.86

1000 0.08 32.23 419.00 14.77 192.04 18.13 235.69 2.01 26.19 12.62 164.11 0.45 5.82

Chronic risk LOC for mammals is 1.



### Table 4.8

. Mammalian Chronic Dietary

- based * RQs for the Use of Dicrotophos on Cotton

. Bold indicates exceedance of the LOC.

Rate (# apps; interval) NOAEC

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0.5 (2; 14d) 1 0.1 210.94 105 96.68 48 118.66 59.33 13.18 6.59 82.62 41.31

* Size class not used for dietary risk quotients

Chronic risk LOC for mammals is 1.- Page 51 of 102

- 

### 4.1.2.2. Birds

Based on the available toxicity data, the avian acute dose

- based and sub

- acute dietary endpoints used for risk assement are 1.22 mg/kg

- bw and 13 mg/kg

- diet, respectively. Dicrotophos is classified as “very highly toxic” to birds on both an acute and sub

- acute basis.

RQs for acute dose

- based exposure exceed the acute non

- listed species LOC (0.5) for all size classes and foraging groups by at least two fold and as much as 926X (small bird, short grass) ( Table 4.9 )

.

On a sub

- acute basis, RQs for all size classes and foraging groups exceed the acute non

- listed species LOC (0.5) by at least two fold and as much as 32X

. RQs resulting from sub

- acute dietary exposure are depi cted in Table 4.10

.

On a chronic dietary basis, RQs for all size classes and foraging groups exceed the the chronic LOC (1.0) by at least 26X and as much as 422X ( Table 4.11 ).- Page 52 of 102

-



### Table 4.9

. Avian Acute Dose

- based RQs for the Use of Dicrotophos on Cotton. Bold indicates exceedance of the LOC.

Rate (# apps; interval) Size

Class (grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 0.5 (2; 14d) 20 0.52 240.24 463.30 110.11 212.34 135.14 260.60 15.02 28.96 94.10 181.46 3.34 6.43

100 0.66 137.00 207.53 62.79 95.12 77.06 116.73 8.56 12.97 53.66 81.28 1.90 2.88

1000 0.93 61.34 65.78 28.11 30.15 34.50 37.00 3.83 4.11 24.02 25.76 0.85 0.91

Acute risk to non

- listed species LOC for birds is 0. 5 Acute risk to listed species LOC for birds is 0. 1



### Table 4.10

. Avian Sub

- a cute Dietary

- based * RQs for the Use of Dicrotophos on Cotton. Bold indicates exceedance of the LOC.

Rate (# apps; interval) LC50

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0.5 (2; 14d) 13 210.94 16.23 96.68 7.44 118.66 9.13 13.18 1.01 82.62 6.36

* Size class not used for dietary risk quotients

Acute risk to non

- listed species LOC for birds is 0. 5 Acute risk to listed species LOC for birds is 0. 1



### Table 4.11

. Avian Chronic Dietary

- based RQs for the Use of Dicrotophos on Cotton. Bold indicates exceedance of the LOC.

Rate (# apps; interval) NOAEC

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0.5 (2; 14d) 0.5 210.94 421.9 96.68 193.4 118.66 237.31 13.18 26.37 82.62 165.24

Chronic risk LOC for birds is 1.0- Page 53 of 102

- 

### 4.1.2.3. Terrestrial Invertebrates

Dicrotophos is classified as highly toxic to honeybees on an acute contact exposure basis

. Per

the Pollinator SAP white paper (USEPA, 2012) , tall grass EECs were calculated separately for

acute oral and acute contact exposure, according to the following equations:

Oral toxicity EEC = (Single application rate) × (110 μg a.i./g per 1 lb a.i.) × (0.2 9 g/day)

Contact toxicity EEC = (Single application rate) × (2.7 μg a.i./bee per 1 lb a.i.)

Acute oral and contact t all grass EEC s of 15.95 μg ai/bee and 1.35 μg ai/bee were divided by the

acute oral and contact LD 50 

### ’s of 0.068 μg ai/bee and 0.076 μg ai/bee

, respectively

, resulting in

acute oral and contact RQs of 234.6 and 17.8, respectively. T he initial screening level RQ s determined for honey bees ( Table 4.12 ) exceed the terrestrial invertebrate LOC (0. 4) by more

than two orders of magnitude on an oral toxicity basis, and more than an order of magnitude on a contact toxicity basis; however, the s e estimate s of risk are considered within the context of other

lines of evidence

. More discussion on the ratio between the LD 50 

### and the expected exposure is presented in the Risk Description section.

Table 4.12

. Terrestrial Invertebrate Oral and Contact Toxicity RQs for the Use of Dicrotophos

on Cotton. Bold indicates exceedance of the LOC.

Rate ( lb a.i./A ) LD 50 (μg

a.i./bee) EECs and RQs

Tall Grass

EEC RQ Oral toxicity

0.068 15.98 234.56

0.5 Contact toxicity

0.076 1.35 17.76

Acute risk LOC for terrestrial invertebrates is 0.4



### 4.1.2.4. Non

- target Terrestrial Plants

Ten different crop species were treated with dicrotophos at the maximum label rate during Tier I seedling emergence and vegetative vigor testing. No definitve effects endpoints were determined from those tests and risk to terrestrial plants is presumed to be negligible.

4. 2. Incident Databa se Review

A review of the Ecological Incident InformationSystem (EIIS) database for incidents involving dicrotophos was conducted on December 5 , 201 2

. Four incidents for dicrotophos are reported in the database ( Appendix D ). Of these, two occurred from use on agricultural areas , one incident resulted from a disposal site, and one use site was undefined

. The 1976 incident resulting from the disposal site ( B0000

- 400

- 19 ; probable ) occurred in Washington State and mortalities of American wige on, common pintail, and mallard were reported. An incident associated with rice- Page 54 of 102

-



### in Texas ( B0000

- 400

- 20; probable) involved ingestion of dicrotophos

- treated rice, and

mortalities of red

- winged blackbird, great

- tailed grackle, brown

- headed cowbird, and mour ning dove were reported. In 1991, dicrotophos applied to cotton in Lauren county, GA ( I000922

- 001 ; unlikely) was associated with mortalities of hundreds of catfish, bream, and bass in a pond 20 to 50 yards from the treated field. In 2002, dicrotophos use d in Desha county, AR ( I018980

- 029 ; highly probable) is associated with the mortalities of 200 greater snow geese, one coyote, and at least one hawk species.

Similarly, a search of the Avian Incident Monitoring System (AIMS; http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm ) was conducted on December 5, 2012 . AIMS is a database administered by the American Bird Conservancy that contains publicly avai lable data on reported avian incidents involving pesticides. Nine incidents involving dicrotophos were found

. Seven incidents are reported from Texas; one from Arkansas; and one from Washington state. All but three incidents have certaint y classificatio ns as “unlikely;” one of these three incidents was already captured by EIIS ( B0000

- 400

- 19 ; probable )

. A 1996 incident from Harris county, Texas ( US Fish and W ildlife Service Law Enforcement

Division Case No. 96

- 0296 ) is classified as highly likely ; o ne red

- tailed hawk and 11 passerine

birds were assessed as moribound

. A 2000 incident from Pulaski county, Arkansas ( US Fish and

W ildlife Service Law Enforcement Division Case No. 00

- 0197) involving dicrotophos and mevinphos is classified as highly likely ; mortalities of dove, grackle, cowbird, and blackbird were reported

. Two other incidents involving misapplication of pesticide

- treated seed were reported and more than 1,000 bird mortalities are associated with these incidents.

Pesticide registrants rep ort certain types of incidents to the Agency as aggregate counts of incidents occurring per product per quarter. One aggregated fish and wildlife incident has been reported to the Agency associated with dicrotophos. It was submitted in the summer of 2004

. Unless further information regarding this aggregate incident is discovered, it will be assumed

that it resulted from registered use

.

The number of reports listed in the EIIS database are believed to be only a small fraction of the total incidents involving organism mortality and damage caused by pesticides. Few resources are assigned to incident reporting. Reporting by states is only voluntary, and individuals discovering incidents may no t be informed on the procedure of reporting these occurrences. Additionally, much of the database is generated from registrant

- submitted incident reports. In addition, incident reports for non

- target organisms typically provide information only on mortalit y events and plant damage incidents. Impacts to non

- commercial beneficial insects and other invertebrates are not likely to be reported. Except for phytotoxic effects in terrestrial plants, sublethal effects for organisms such as reduced growth or impaire d reproduction are rarely reported. Because of these logistical difficulties, EIIS is most likely a minimal representation of all pesticide

- related ecological incidents.

Therefore, the weight of evidence based on the currently available data suggests that direct

effects to avian and mammalian species are expected from the currently registered use of dicrotophos.- Page 55 of 102

-



### 4.3

. Risk Description

The results of risk estimation indicate that registered uses of dicrotophos yield acute and chronic

LOC exceedance s for a quatic invertebrates (freshwater and estuarine/marine)

. RQs calculated for fish and aquatic plants did not result in LOC exceedances.

Acute and c hronic risk to birds and mammals from dicrotophos is indicated on both a dietary and

dose basis

. Acute risk to terrestrial invertebrates is indicated based on dermal contact toxicity and exposure estimates . Risk to t errestrial plants is presumed to be neglible, based on the nondefinitive endpoints determined from Tier I studies with crop species.

Several refinements to the risk determinations may be attempted in the final version of this risk assessment. These refinements include consideration of biological factors of individual listed species and the potential co

- occurence of listed species and register ed use sites where dicrotophos may be used.

4.3 .1 Exposure to Aquatic Organisms

Surface water EECs resulting from applications of dicrotophos to cotton are conservative estimates of exposure for the use of dicrotophos as a broadcast insecticide . Applica tion practices were conservatively modeled by using maximum application rates and minimum application intervals. Environmental fate data were conservatively represented by using the 90 th 

### percentile

mean of metabolism half

- life estimates. Finally, scenari o selection was conservatively performed by modeling run

- off prone soils that drain to a small pond without an outlet. Low

EECs for dicrotophos come as a result of high metabolism rates. However, modeling values are only two times larger than the highest reported monitoring value and higher monitoring values may be found with more targeted monitoring approaches.

The tree injection use pattern is not expected to appreciably contribute to aquatic exposure

. Theoretically, a quatic exposures could result from dicrotophos entering soil environments

, which could occur if the chemical is translocated primarily to the leaves, and the leaves fall to the soil and decompose. Dicrotophos degrades readily in soil

, and through this process of translocation

in the t ree and foliage degradation , it can be expected that dicrotophos will be substantially degraded before it reaches aquatic environments. Therefore, discussion of dicrotophos risk to aquatic animals (Section 4.3.1.1) is limited to exposure resulting from th e registered use on

cotton.

Spray drift exposure to aquatic organisms is also a viable exposure pathway. Concentrations of

0.6 ppb in water trigger the Endangered Species LOC (based on Daphnia magna toxicity endpoint of 12.7 ppb). This concentration is achieved at distances up to 331 feet from the edge of field according to AgDRIFT v 2.01 for aerial applications. Ground applications yielded

maximum concentrations only as high as 0.6 ppb at three feet from the edge of field ; therefore spray drift resulti ng from ground applications would be of limited concern, especially in comparison to aerial applications. Note that all broadcast uses allow aerial applications.- Page 56 of 102

- 

### 4.3 .1.1. Risks to Aquatic Animals

B a sed on the available data, risk to freshwater or estuarine/marine fish is not expected on an acute exposure basis. The highest RQ from all modeled use patterns is 0.003

, well below the listed species LOC of 0.05 . Neither is chronic risk to fish expected; RQs are all less than 0.001.

T he acute non

- listed species LOC (0.5) for effects to freshwater invertebrates and acute restricted

use LOC (0.1) for effects to estuarine/marine invertebrates are exceeded , with RQ s as high as 1. 33 and 0. 22 for freshwater and estuarine species, respectively

. Chronic risk LOCs (1.0) are also exceeded; RQs were determined to be as high as 7.2 and 3.97 for freshwater and estuarine

invertebrates

, respectively

. Both acute and chronic toxicity data indicate that freshwater

invertebrates are more sensitive than estuarine/marine invertebrates to dicrotophos exposure

.

4.3 .1.2. Risks to Aquatic Plants

Based on the available toxicity information on Lemna gibba and Pseudokirchneriella subcapitata , the use of dicrotophos on cotton do es not result in RQ exceed ances of the LOC for

listed aquatic plant s, since all RQ s are less than 0.01

.

4.3.2. Exposure to Terrestrial Organisms

Dicrotophos is registered for use as a foliar spray on cotton and also as a tree injection for

ornamental trees. Each use pattern has u nique exposure uncertainties ; therefore

, discussion of terrestrial exposure will be subdivided according to use pattern. Specific to the cotton use

pattern, a pplication practices were conservatively modeled by using maximum application rates and minimum applic ation intervals. T he spray drift model AgDrift provide s helpful bounds

which define the spatial extent of risk concern resulting from off

- field drift at currently registered dicrotophos application rates. Sections 4.3.2.1., 4.3.2.2., and 4.3.2.3

. contain descriptive characterization of the AgDrift output and the associated off

- field risk implications for mammals, birds, and terrestrial insects, respectively.

4.3 .2

. 1. Risks to Mammals

Cotton use pattern

Acute upper bound Kenaga RQs derived for mammals in the Risk Estimation section of this

assessment indicate acute listed m ammalian risk LOC (0.1) exceedances for all but 1000 gram granivore mammals (RQ = 0.07)

. Based on the EEC values from T

- REX and the LD 50 

### from the

available ac ute rat study, the highest RQ value for 15 gram mammals foraging on short grass

— the most sensitive size class and forage item combination

— is 11.44

.

When assessing potential chronic risk to mammals, in accordance with the overview document, the dietary

- based NOAEC is converted to a dose

- based NOAEL using data from the HED study,- Page 57 of 102

-



### which can be scaled to different mammalian size classes. The dose

- based R Qs are calculated using a body weight adjusted and consumption

- weighted equivalent dose, as determined in the study. The adjustments account for the fact that smaller

- sized animals have to consume more food in terms of their body weight than larger animal s and that there is differential sensitivity to chemicals based on body size. By expressing the Kenaga nomogram

- estimated residues in terms of daily equivalent dose, estimated environmental concentrations can then be compared to the

dose

- based NOAEL

. D os e

- based and dietary

- based chronic RQs exceed the LOC (1.0) for all forager types

. Dose

- based chronic RQs range from 5.82 to 915, and dietary based chronic RQs range from 6.59 to 105. The exceedances for dicrotophos are greater than 915

- fold (dose

- based)

and 100

- fold (dietary

- based) for short grass mammalian foragers

. These exceedances are based on reduced pup survival observed in a three

- generation rat reproduction study

. Since terrestrial application residues exceed 2 mg ai/kg dietary item ( i.e

., the m ammalian reproduction NOAEC )

for at least 105 days (fruits/pods/seeds) and as many as 250 days (short grass) following the first application of dicrotophos, there is a high degree of confidence in the prediction of adverse

chronic effects.

EECs exceed the mammalian acute non

- listed species LOC (0.5) for 164 days after application for short grass, assuming a 35

- day half life and two applications of 0.5 lb a.i./A applied at a 14

- day interval ( Figure 4.1 ). With the same model input parameter s , EECs exceed the mammalian

acute non

- listed species LOC for 1 16 to 134 days following application for all other forage types except fruits/pods/seeds, where the mammalian acute non

- listed species LOC is exceeded for 23 days following the first application

.

Even under a less conservative T

- REX exposure scenario, m ean Kenaga acute and chronic RQs exceed the acute listed species or chronic LOC for all size classes and forage types, except for granivores with RQs (acute dose

- based) less than the acute listed species LOC fo r all size

classes

.

To spatially examine the potential risk of spray drift, simulations were performed with the

program AgDRIFT

. It was determined that s pray drift EECs yield acute dose

- based RQs that exceed the acute listed species LOC (0.1) for short grass even at the model limit (997 feet from the treated field). However, s pray drift is not of acute dose

- based risk concern for listed granivore mammals. AgDRIFT also indicates that spray drift EECs yield chronic dietary RQs that exceed the LOC (1.0) for short grass even at the model limit (997 feet from the treated field). Even considering the least conservative forage class (fruits/pods), RQs resulting from spray drift

EECs would exceed the chronic LOC at least as far as 650 f ee t from the treated fie ld.

One of the uncertainties regarding chronic RQs for dicrotophos is the use of the 35 day default foliar dissipation half

- life. In some fate studies, dicrotophos is shown to degrade much more quickly. In an effort to address this uncertainty, RQs were modeled using a hypothetical three day half

- life. Use of a t hree day half

- life results in a 40% reduction in the RQs ( e.g. 5.82 to 3.44). However, even if data were available to reduce the foliar dissipitation half

- life used in the model to three days, all size class and forage c lass exceedances would remain , albeit not as far

off

- field as for the 35

- day half life assumption.- Page 58 of 102

-



### Tree Injection Use Pattern

The tree injection use pattern is a potential avenue of dicrotophos exposure for mammals. Without an understanding of the systemic nature of dicrotophos in the tree, it is not possible to accurately estimate dicrotophos concentrations by plant tissue type and thereby associate dietary items with an exposure magnitude. Mammalian diets could con sist of b ark, foliage, nuts, or

some combination of the three and

, in the absence of plant tissue residue data (and dissipation rates)

, are all plausible exposure pat hways . While crop tree species have been of f

- labeled, trees that produce mast would not b e considered crop tree species. Depending on the translocation of

tree

- injected dicrotophos to seeds, mast producing species such as oaks could forseeably be of exposure concern for nut

- consuming mammals.

Since a mammalian acute dietary toxicity endpoint ( i.e. , an LC 50 

### ) is not availab le, the chronic NOAEL (2.0 mg/kg diet) serves as a conservative estimate of acute dietary

- based toxicity

. Given the conservative assumption that dicrotophos exclusively accumulates in the foliage of injected trees resulting in an exposure to concentrations of 1,000 ppm, the dietary RQ for

mammals is 500 . Given the assumption that dicrotophos is evenly distributed through sapwood and foliage of injected trees resulting in an exposure to concentrations of 31 ppm, the dietary RQ

for mammals is 15.5

. This RQ exceeds the non

- listed species LOC (0.5) by more than 30 fold.

Note that the assumption of even distribution is not conservative if considering herbivorous consumption of leaves

, bark , or seeds alone. Still, these assumpt ions represent a spectrum of presumed exposure with all conclusions indicating the tree injection use pattern produces

exceedances of the acute LOC.- Page 59 of 102

-



### Figure 4.1 . Mammalian LOCs Superimposed on Residue Decline Curve- Page 60 of 102

- 

### 4.3 .2

. 2. Risk to Birds

Cotton Use Pattern

The southeastern United States and Mississippi Valley, some of the largest cotton growing areas of the country, fall within the delineation of two major migratory corridors traveled by neotropical migrant birds: the Mississippi and Atlantic flyways. Two field studies conducted in the late 1980’s on dicrotophos

- treated c otton fields in Alabama and Arizona documented the occurence of numerous avian and herpetile species in wildlife surveys. In Alabama, 75 species of bird were identified during surveys, with 29 of those species using the cotton fields. In Arizona, 102 spe cies of birds were identified during surveys, 36 of those species observed within

the borders of the cotton field.

Similar to the mammalian chronic EECs, acute avian EECs are calculated on both a dietary and

dose basis. For the cotton use, acute dose

- bas ed upper bound Kenaga RQs exceed the acute non

listed species LOC (0.5) for all size classes and foraging groups. Sub

- acute dietary and chronic dietary upper bound Kenaga RQs exceed the acute non

- listed species LOC (0.5) and chronic

LOC (1.0), respectively, for all forager group types

. Considering t he magnitude of acute non

listed species LOC exceedances, as much as 926

- fold, there is a high degree of certainty that avian species will be adversely affected by dicrotophos applied to cott on

.

EECs exceed both the avian acute listed species LOC (0.1) and avian chronic LOC (1.0) for 270 days and 320 days , respectively, after first application for short grass, assuming a 35

- day half life

and two applications of 0.5 lb a.i. /A applied at a 14

- day interval ( Figure 4.2 ) . With the same model input parameter, EECs exceed the avian acute non

- listed species LOC (0.5) for 14 0 to 1 6 0 days following application for all other forage types except fruits/pods/seeds, where the avian

acute non

- listed spe cies LOC is no longer exceeded after day 48

. Since terrestrial application residues exceed 0.5 mg ai/kg dietary item ( i.e.

, the avian reproduction NOAEC ) for more than

267 days following the first application of dicrotophos for all forager types except consumers of fruits/nuts/seeds ( dicrotophos residues above the NOAEC through day 180 ) , there is a high degree of confidence in the prediction of adverse chronic effects. Even under a less conservative

T

- REX exposure scenario, m ean Kenaga acute and chronic RQs exceed the acute listed species

or chronic LOC for all size classes and forage types.

To spatially examine the potential risk of spray drift, simulations were performed with the spray drift modeling program AgDRIFT

. It was determined that s pray drift EECs yield acute dose

based RQs that exceed the acute listed species LOC (0.1) for short grass even at the model limit (997 feet from the treated field) , and for all other forage classes at least 730 feet from the treated

f ield . S pray drift EECs yield subacute dietary RQs that exceed the acute listed species LOC (0.1) for short grass even at the model limit (997 feet from the treated field) , and for all other forage classes at least 108 feet from the treated field . S pray d rift EECs yield chronic dietary RQs that exceed the LOC (1.0) for short grass even at the model limit (997 feet from the treated field)

, and for all other forage classes at least 250 f ee t from the treated field.

The STIR model output indicates that inhalation may be an exposure pathway of concern for avian species . Considering that the available acute mammalian inhalation toxicity study used a- Page 61 of 102

-



### supersaturated solution and recorded no mortalities, and that exposure to droplets in the field

would be ex pected to be of a lesser duration ( i.e. , less than four hours), inhalation is not regarded

as the primary route of exposure eliciting observed avian toxicological response

.

One of the uncertainties regarding chronic RQs for dicrotophos is the use of the 35 day default foliar dissipation half

- life. In some fate studies, dicrotophos is shown to degrade much more quickly. In an effort to address this uncertainty, RQs were modeled using a hypothetical three day half

- life. Use of a t hree day half

- life resul ts in a 40% reduction in the RQs ( e.g. 5.82 to 3.44). However, even if data were available to reduce the foliar dissipitation half

- life used in the model to three days, all forage c lass exceedances would remain , albeit not as far off

- field as for

the 35

- d ay half life assumption

.- Page 62 of 102

-



### Figure 4.2 . Avian LOCs Superimposed on Residue Decline Curve

Chronic LOC Avian acute

LOC

Avian acute listed species LOC- Page 63 of 102

-



### Birds are generally used as surrogates for terrestrial

- phase amphibians and reptiles. However, these taxa are poikilotherms (body temperature varies with environmental temperature) while birds are homeotherms (temperature is regulated, constant, and large ly independent of environmental temperatures). Therefore, they tend to have much lower metabolic rates and lower caloric intake requirements than birds or mammals. As a consequence, birds are likely to consume more food than amphibians o n a daily dietary intake basis, assuming similar caloric content of the food items. The use of avian food intake allometric equation as a surrogate to reptiles and amphibians is likely to result in an over

- estimation of exposure and risk for reptiles

and terrestrial

- phase amphibians. Therefore, T

- REX has been refined to the T errestrial

H erpetofaunal E xposure and R esidue P rogram S imulation (T

- HERPS) model (v1.0, 5/15/2007), which allows for an estimation of food intake for poikilotherms using the same basic procedure

as T

- REX to estimate food intake. It is possible that the final listed species effects determination

will utilize T

- HERPS as a refinement, should exposure of herpetofauna be deemed likely.

Tree Injection Use Pattern

T he tree injection use pattern is a potential route of dicrotophos exposure for avian species

. Without an understanding of the systemic nature of dicr otophos in the tree, it is not possible to accurately estimate dicrotophos concentrations by plant tissue type and thereby associate dietary items with an exposure magnitude. In contrast to mammalian species which are likely to

consume bark, foliage, nuts , or some combination of the three, birds would more likely consume fruits, nuts, and seeds ; encountering dicrotophos residues (if present) through those dietary items

. While the label stipulates that this product is not for use on crop species, it is imp ortant to understand that even the ornamental varieties of many tree species still produce fruits , nuts, or
seeds that are attractive forage items for birds . Secondary exposure is also of concern for avian species that forage on insects, which may encount er dicrotophos residues via their insect prey.

The subacute dietary exposure endpoint for birds is an LC 50 

### of 13 mg/kg diet or 13 ppm. Given the conservative assumption that dicrotophos exclusively accumulates in the foliage of injected trees resulting in an exposure to concentrations of 1,000 ppm, the dietary RQ for birds is 77 (for the purposes of this exer cise, the foliage is considered an appropriate surrogate for fruits/nuts/seeds)

. Assuming even distribution of dicrotophos through out the sapwood

, foliage

, and nuts/fruits/seeds of injected trees results in an exposure concentration of 31 ppm, with a

corr esponding avian dietary RQ of 2.4. This RQ exceeds the non

- listed species LOC (0.5) by

more than 4 fold. N ote that the assumption of even distribution is not conservative if considering herbivorous consumption of fruits, nuts, or seeds alone. Still, t he se assumptions represent a spectrum of presumed exposure with all conclusions indicating the tree injection use pattern produces exceedances of the acute LOC.

4.3 .2

. 3. Risk to Terrestrial Invertebrates

Of the available data on various non

- target terres trial insects, honeybees are the most sensitive terrestrial invertebrate species. Dicrotophos is classified as highly toxic to honeybees on an- Page 64 of 102

-



### acute contact exposure basis, with an LD 50 

### of 0.076 μg ai/bee. The honey bee acute oral LD 50 

### is

0.068 μg ai/bee

. RQ s for terrestrial invertebrates were calculated separately for acute oral and contact exposure, using tall grass EEC s of 15.95 μg ai/bee and 1.35 μg ai/bee

, divided by the

acute oral and contact LD 50 

### ’s of 0.068 μg ai/bee and 0.076 μg ai/bee

, respectiv ely . The resulting RQ s for acute oral and contact exposure, 234.6 and 17.8, respectively, are compared to a LOC of

0.4 a s discussed in the Pollinator SAP white paper (USEPA, 2012) . Thus , the RQ exceeds the LOC by more than an order of magnitude. However, the screening level RQ values are based on

model

- generated exposure values which are intended to be conservative. Also, the RQ value s

are based on effects to individual bees under laboratory conditions and there is uncertainty regarding the poten tial effects to bee colonies under actual use conditions. R esidues on foliage have been found to remain toxic to bees and other beneficial insects for as long as 16 days (MRID 05013577). Although the risk estimate s suggest that t errestrial invertebrate s may be impacted by dicrotophos use and that indirect effects to plants with obligate relationships to insect species may result , there are relatively few incident reports for dicrotophos and none of these reports involved bees. Since dicrotophos is used o n cotton and since cotton is used by some beekeepers to produce honey, the proximity of bee colonies to dicrotophos use areas may be high; however, in a survey of pesticide residues in managed be e colonies (Mullin et al. 2010), no dicrotophos residues were reporte d. While the absence of bee kill incident data cannot be construed as the absence of incidents and while the Mullin et al. 2010 study cannot be considered an exhaustive investigation of pesticide residues in honey bee colonies, these sources of

in formation serve as lines of evidence that the screening

- level risk estimates while high may not accurately reflect the risk. Although other organophosphate pesticides have been detected in bee colonies and have been associated with bee kill events, these data may reflect the more widespread use of the organophosphates on a range of pollinator

- attractive crops. Also, since organophosphate insecticides such as dimethoate have been used as referen ce toxicants in both laboratory and semi

- field based studies, it is possible that high toxicity of these compounds results in the loss of the scout and forage bees and that sufficiently large quantities of toxicant may not be transported back to the colony to result in colony

- level effects. At this time, there is

un certainty regarding the actual risks of dicrotophos use to bees given the lack of colony

- level studies; however, the other lines of evidence available for the compound do not indicate that the compound is being detected in colonies nor have bee incidents b een reported to have been associated with the use of the compound.

Specific to the tree injection use pa ttern, potential exposure of non

- target insect pollinator s pecies

to dicrotophos is plausible , although the magnitude of residue concentrations is unc ertain in the absence of residue data from dicrotophos

- treated trees

. Many of the tree species listed on the label (e.g., ash, crabapple, linden, locust, maple, stone fruit trees) are attractive sources of pollen and/or nectar for insect pollinators.

4.3 .2

. 4. Risk to Terrestrial Non

- target Plants

Since no adverse effect s were reported in either the seedling emergence or vegetative vigor

studies at the maximum dicrotophos application rate, phytotoxic effects are not expected on the

use site s . Effects offsite are also not expected as exposures would be below the maximum application rate.- Page 65 of 102

-



### 4.4

. Uncertainties and Data Gaps

4.4 .1. Fate and Transport

The tree injection use pattern (EPA Reg. No. 7946

- 11) does not limit the number of applications that can be made in a given year or season. Further, the stated application rate is based on number of capsules for a given tree size. However, the size of th e capsule can be variable according to the label which would result in substantially different applications depending on capsule size. Given these uncertainties, maximum single application and maximum annual application cannot be precisely determined.

Th e fate of dicrotophos when injected into the tree is also a great uncertainty. The suite of

chemical fate data EFED receives has little bearing on how a chemical behaves when injected into a tree. The rates of degradation in the tree, mobility to various parts of the tree, and formation of degradates cannot be characterized by current data. Though it is not detected in soil

metabolism studies , it is possible that monocrotophos is formed in the tree as monocrotophos was formed in foliar dislodgeable resid ue study ( MRID 44731001 )

. The study showed detections of monocrotophos over the level of quantitation after each of two applications in Texas. Monocrotophos was not detected in the Mississippi test. This degradate of dicrotophos is more toxic to many ta xa than dicrotophos itself.

Dicrotophos degrades readily in aerobic soil with a half

- life of 2.7 days and is the dominant route of dissipation. Model estimates for aerobic soil and aquatic metabolism rely on only one study testing one soil to derive mo del parameters. The 2.7 day half

- life is multiplied by uncertainity factors to derive the parameters but it must still be considered that one soil is being used to represent thousands of soils and microbial communities with variable types and rates of

met abolism in addition to many aquatic environments with similar variability.

4.4 .2. Effects
The formation and decline of monocrotophos residues in and/or on plant tissue is a considerable uncertainty in this assessment. Monocrotophos is known to be more toxic to avian species than dicrotophos on an acute basis, and while residues of monocrotophos on foliage are presumed to be lesser (on a mass per unit volume or mass per unit area basis)

, the enhanced toxicity of this

co mpound may effectively extend the time of acute risk LOC exceedances following dicrotophos application.

The available avian acute and subacute studies are not robust. Many of the available studies were not performed in accordance with the current guide lines. Fewer treatment levels than

recommended (four instead of five) is one shortcoming of the studies. Treatment levels were poorly selected

, such that few, if any, concentrations or doses resulted in partial kills, meaning that mortalities by treatmen t were commonly zero or 100 percent. For most studies, u ncertainties

would be reduced if additional study conduct details were available. Specifically, the percent active ingredient of the test material for the most sensitive acute oral and sub

- acute die tar y test species is a considerable uncertainty. The avian RQs reported in this assessment may underestimate toxicity since the compound purity was presumed to be technical grade.- Page 66 of 102

-



### A n acceptable foliar residue toxicity study with honey bees (OCSPP 850.3 030) would allow for

determination of a 24

- h RT 25 

### . This data would reduce uncertainties surrounding the length of time post

- application that residues of dicrotophos on foliage are toxic to honey bees.

A chronic fish study with an estuarine/marine species exposed to dicrotophos is not available

. While it is uncertain whether estuarine/marine fish species may be more sensitive to dicrotophos exposure of chronic duration than freshwater species, available data indicate that estuarine/marine species are nearly 14 fold less sensitive to dicrotophos exposure of acute duration than freshwater fish species tested.

5. Endocrine Disruptor Screening Program (EDSP)

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxici ty, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturati on, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of the Preliminary Problem Formulation for Registration Review (USEPA, 2008), EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as req uired by FFDCA

se ction 408(p), dicrotophos is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

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

- tiered approach to making the statutorily required

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

- related effects caused by the substance, and

establish a dose

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

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

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013 5 

### and includes some

5 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of

chemicals.- Page 67 of 102

-



### pesticide s scheduled for registration review and chemicals found in water

. Neither of these lists should be construed as a list of known or likely endocrine disruptors

.

Dicrotophos is on List 2. List 2 represents the next set of chemicals for which EPA intends t o issue test orders/data call

- ins in the near future. For further information on the status of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website. 6



### 6

. Federally Threatened and Endangered (Listed) Species Concerns

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2), requires all federal agencies to consult with the National Marine Fisheries Service (NMFS) for marine and

anadromous listed species, and/or the United States Fish and Wildlife Service (USFWS) for listed wildlife and freshwater organisms, if they are proposing an "action" that may affect listed species or their designated critical habitat. Each federal agency is required under the Act to ensure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of designated critical habitat. To jeopardize the cont inued existence of a listed species means "to engage in an action that reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction , numbers, or distribution of the species" (50 C.F.R. § 402.02).

To facilitate compliance with the requirements of the Endangered Species Act (subsection (a)(2)), the Office of Pesticide Programs has established procedures to evaluate whether a proposed r egistration action may directly or indirectly appreciably reduce the likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of any listed species (USEPA, 2004). After the Agency’ s screening level risk assessment is conducted, if any of the Agency’s listed species’ LOCs are exceeded for either direct or indirect effects, an analysis is conducted to determine if any listed or candidate species

may co

- occur in the area of the propose d pesticide use or areas downstream or downwind that could be contaminated from drift or runoff/erosion. If listed or candidate species may be present in the proposed action area, further biological assessment is undertaken. The extent to which listed sp ecies may be at risk is considered, which then determines the need for the development of a more comprehensive consultation package, as required by the Endangered Species Act.

The federal action addressed herein is the proposed registration renewal of dic rotophos on agricultural ( i.e. , cotton) and silvicultural use sites and it is expected that its use as a tree injection pesticide could occur nationwide.

6 .1. Action Area

For listed species assessment purposes, the action area is considered to be the area affected directly or indirectly by dicrotophos use and not merely the immediate area where dicrotophos is applied. At the initial baseline, the risk assessment considers broadly described taxonomic

6 http://www.epa.gov/endo/- Page 68 of 102

-



### groups and conservatively a ssumes that listed species within those broad groups are co

- located with the pesticide treatment area. This means that listed terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site and listed aquatic organisms are ass umed to be located in a surface water body adjacent to the treated site.

6 .2. Taxonomic Groups Potentially at Risk

If the assumptions associated with the baseline action area result in RQs that are below the listed species LOCs, a "no effect" determination conclusion is made with respect to listed species in that taxa, and no further refinement of the action area is necessary. Furthermore, RQs below the listed species LOCs for a given taxonomic grou p indicate no concern for indirect effects on listed species that depend upon the taxonomic group for which the RQ was calculated . However, in situations where the screening assumptions lead to RQs in excess of the listed species LOCs for a given taxonomi c group, a potential for a "may affect" conclusion exists and may be associated with direct effects on listed species belonging to that taxonomic group or may extend to indirect effects upon listed species that depend upon that taxonomic group as a resourc e. In such cases, additional information on the biology of listed species, the locations of these species, and the locations of use sites are considered to determine the extent to which screening assumptions regarding an action area apply to a particular listed organism. These subsequent refinement steps will consider how this information would impact the action area for a particular listed organism and potentially include areas of exposure that are downwind and downstream of the pesticide use

site.

Assessment endpoints, exposure pathways, and the concept ual models addressing registered dicrotophos uses, and the associated exposure and effects analyses conducted for the dicrotophos

baseline risk assessment are in Sections 2 to 3 . The assessment endpo ints used in the baseline risk assessment include those defined operationally as reduced survival and reproductive impairment for both aquatic and terrestrial animal species and survival, reproduction, and growth of aquatic and terrestrial plant species fr om both direct acute and chronic exposures. These assessment endpoints are intended to address the standard set forth in the Endangered Species Act requiring federal agencies to ensure that any action they authorize does not appreciably

reduce the likelih ood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of the species. Risk estimates (RQs) which, integrating exposure and effects, are calculated for broad based taxonomic groups in t he screening

- level risk assessment presented in Section 4.

Data on exposure and effects collected under laboratory and sometimes field conditions are evaluated in the screening

- level risk assessment for nonlisted and listed species. Both acute endangered species and chronic risk LOCs are considered in the baseline risk assessment to identify potential effects (or absence thereof) to listed species. This section identifies direct effect concerns, by taxa that are triggered by exceeding endangered LOCs in the screening

- level

risk assessment ( Table 6.1 ) Where applicable, an evaluation of the potential probability of individual effects for exposures that may occur at the established listed species LOC is presented

in Section 6.2.1 . Data on exposure and effects collected under field and laboratory conditions are evaluated to make determinations on the predictive utility of the direct effect screening assessment findings to listed species.- Page 69 of 102

-



### Additional Considerations for Listed Species



### Based on this sc reening

- level assessment, there are potential risks of direct effects to listed and

non

- listed freshwater and estuarine/marine invertebrates, mammals, birds (birds are surrogates for terrestrial phase reptiles and amphibians), and terrestrial invertebrates from the use of dicrotophos on cotton . Listed species of freshwater and estuarine/marine invertebrates, mammals, birds, and terrestrial invertebrates may also be affected through indirect effects because of the potential direct effects on listed and non

- listed species. Potential direct effects on

listed and non

- listed freshwater and estuarine/marine invertebrates (cotton use pattern only), mammals, birds, and terrestrial invertebrates from the use of dicrotophos may be associated with

modification of P ri mary C onstituent E lements (PCEs) of designated critical habitats, where such designations have been made. However, a t this current stage of the Registration Review process, it is premature to make effects determinations for listed species until further sc ientific analysis

and refinements are conducted , based on recommendations received from the National Academy of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at http://www.nap.edu/catalog.php?record_id=18344 . The NAS report outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that are compliant with the Endangered Species Act (ESA) and the F ederal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

The EPA along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA),

released a s ummary of their implementation plan for assessing risks of pesticides to listed species ahead of the stakeholder workshop held on November 15, 2013. This plan was developed in response to the NAS’ recommendations, including a common approach to risk asses sment as a way of addressing scientific differences between EPA and the Services. During the workshop, the agencies received feedback from the public on the interim scientific approaches that were developed as part of the initial implementation of the NAS recommendations. These approaches will be jointly implemented and vetted as part of a phased iterative process. Once fully vetted, EPA will further refine the listed species effects determination portion of this risk assessment.

To make effects deter minations for individual listed species, useful refinements may include, but are not limited to, analyses of: 1) more detailed, species

- specific ecological and biological data; 2) more detailed and accurate information on dicrotophos use patterns; and 3) s ub

- county level spatial proximity data for the co

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

EFED is currently developing tools that are expected to furt her refine the assessment and are designed to support effects determinations for individual federally listed species and their designated critical habitats (where applicable). Scientific information obtained from the

Services , and other reliable sources i s being collated by EFED to address all currently listed species. Th is information is be ing stored in an Office of Pesticide Programs (OPP) P esticide

R egistration I nformation S yste M (PRISM) listed species knowledgebase. The listed species knowledgebase c onsist s of an information repository that houses biological and behavioral information relevant to individual species ( e.g. , habitat, diet, and life history, including specific- Page 70 of 102

-



### temporal and spatial associations) and a document repository that contains supp orting documents ( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial taxa, biological information relevant to the assessment ( e.g ., diet and body weight) will be used to parameterize exposure estimates using a m ethod consistent with currently used methods in the

T

- REX and T

- HERPS models.

Refinements will also include more detailed analyses of the registered uses and specific use patterns that result in either “Likely to Adversely Affect” (LAA) or “Not Likely t o Adversely Affect” (NLAA) determinations for federally listed species. The analyses may include more information on where, when, and how dicrotophos is used on all use sites

. Actual usage data (when available) and national land

- cover datasets that indic ate potential use sites [ e.g ., N ational

L and C over D ataset (NLCD), C rop land D ata L ayer (CDL)] may be used to support a more refined analysis of where dicrotophos is reasonably expected to be used. Similarly, refinements

on the timing of applications and a more in

- depth exploration of agronomic practices for dicrotophos may be included as part of the refinement.

The refinements based on individual species data; additional, detailed usage information, when

availabl e; and recommendations from the NRC report are expected to help to more accurately identify potential areas of effect and to better inform effects and habitat determinations for listed species and any designated critical habitats.- Page 71 of 102

-

Table 6. 1

. Preliminary Conclusions for Potential Direct Effects to Federally Listed Taxa Associated with the Registered Uses of Dicrotophos, Based on

Best Available Data

.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

aquatic plants

– monocots and dicots No effect

Aquatic vascular and

nonvascular plants No effect

Listed Animal Taxon Potential Direct Effects

Acute Notes Chronic Notes

Terrestrial invertebrates Yes

1 E ffect to aquatic invertebrates uncertain for the tree injection use pattern.

2 Estuarine/marine acute invertebrate RQ exceeds LOC by 3.4 fold for cotton use pattern

. ND

3 E ffect to aquatic invertebrates uncertain for the tree injection use pattern.

4 No effect to estuarine/marine fish species from chronic aquatic exposure to the TGAI,

unless estuarine/marine fish

are more than 1000 times as

sensitive as the fathead minnow tested

in MRID 48482901. Mammals Yes Yes

Birds Yes Yes

Reptiles Yes Yes

Amphibians (terrestrial phase) Yes Yes

Amphibians (aquatic phase) No effect No effect

Freshwater fish No effect No effect

Freshwater

invertebrates Yes 1 Yes 3

Molluscs No effect ND- Page 72 of 102

-

Listed Plant Taxon Potential Direct Effects

Estuarine/marine fish No effect No effect 4

Estuarine/marine

invertebrates Yes 1,2 Yes 3

ND Not determined.- Page 73 of 102

-



### 6 .2.1. Probit Dose

- Response Analysis

The Agency uses the probit dose

- response relationship as a tool for providing additional information on the potential for acute direct effects to aquatic and terrestrial animals (USEPA, 2004). As part of this evaluation, the acute RQ for listed species is presented in terms of the chance of an individual event ( i.e. , mortality or immobilization) should exposure at the EEC actually occur for a species with sensitivity to dicrotoph os on par with the acute toxicity endpoint selected for RQ calculation. To accomplish this interpretation, the Agency uses the slope of the

dose

- response relationship available from the toxicity study used to establish the acute toxicity

measures of effec t for each taxonomic group that is relevant to this assessment. The individual effects probability associated with the acute RQ is based on the mean estimate of the slope and an assumption of a probit dose

- response relationship. In addition to a single e ffects probability estimate based on the mean, upper and lower estimates of the effects probability are also provided to account for variance in the slope, if available. Based on the available acute toxicity for dicrotophos, a summary of the probit dose

- r esponse analysis is provided in Table 6 .2 . If no dose response information is available to estimate a slope for this analysis, a default slope assumption of 4.5 (with lower and upper bounds of 2 to 9) (Urban and Cook, 1986) is used.

Individual effect probabilities are calculated based on an Excel spreadsheet tool IECV1.1 (Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP, Environmental Fate and Effects Division (June 22, 2004). The model allows for such calculations by enterin g the mean slope estimate (and the 95% confidence bounds of that estimate) as the slope parameter for the spreadsheet. The desired threshold for the probability of an individual effect is entered as the listed species LOC. In addition, the probability of an individual effect is also derived based on the calculated acute RQ, if available.

The probabilities of an individual acute direct effect ( i.e. , mortality) for each taxa for which there is a definitive RQ are presented in Table 6 .2. These reflect a de fault average slope of 4.5 ( e.g. chance is 1 in 4.3 X 10 5 

### ). If the true dose response curve were shallower, the chance of an individual effect increases ( e.g. slope of 2, chance is 1 in 48).- Page 74 of 102

-



### Table 6 .2. Summary of D icrotophos Probit Dose Response Analy sis for Listed Species

Taxa (study type) Acute Effect Slope (95% C.I.) Chance of Individual Effect at Listed Species LOC (95% C.I.) Chance of Individual

Effect at Derived Acute RQ (95% C.I.)

Bird oral dos e Mortality Default Slope = 4.5 (2

– 9) 1 in 2.9E+05

(1 in 44 to 1 in 8.9E+18) 1 in 2.34 to 1 in 1 1

Bird dietary Mortality Default Slope = 4.5 (2

– 9) 1 in 2.9E+05

(1 in 44 to 1 in 8.9E+18) 1 in 1.97 to 1 in 1 2

Mammal oral dose Mortality Default Slope = 4.5 (2

– 9) 1 in 2.9E+05

(1 in 44 to 1 in 8.9E+18) 1 in 6.38E+06 to 1 in 1 3

Freshwater f

ish Mortality

Default Slope = 4.5 (2

– 9) 1 in 4.18E+08

(1 in 216 to 1 in 1.75E+31) 1 in 5.25 E+ 26 4

(1 in 1.23E+06 to 1 in 7.46E+102)

Estuarine/marine fish Mortality Default Slope = 4.5 (2

– 9) 1 in 4.18E+08

(1 in 216 to 1 in 1.75E+31) 1 in 6.12E+61 5

(1 in 1.45E+13 to 1 in 3.80E+242)

Freshwater invertebrates Immobilization Slope = 3.3 (

- 1

– 7.7) 1 in 1.14E+05

(1 in 1 to 1 in 1.57E+23) 1 in 1.31 6
(1 in 2.42 to 1 in 1.05)

Estuarine/marine

invertebrates Immobilization Slope = 5.3 (

- 7.7

– 18) 1 in 3. 73E+11 (1 in 1 to 1 in 7.23E+120) 1 in 7.75E+02 7

(1 in 1 to 1 in 1.45E+24)

1 Acute RQ for bird (oral) 0.91

- 463

2 Acute RQ for bird (dietary) 1.01

- 16.2

3 Acute RQ for mammal 0.073

- 11.4

4 Acute RQ for freshwater fish 0.004

5 Acute RQ for estuarine/marine fish 0.0002

6 Acute RQ for freshwater invertebrates = 1.65

7 Acute RQ for estuarine/marine invertebrates = 0.27



### Based on the model output, the chance of individual effect at t he derived acute RQ may be considered “likely” for avian dose and dietary exposure, and for freshwater invertebrate exposure. The chance of individual effect at the derived acute RQ is not as probable for freshwater fish, estuarine/marine invertebrates, a nd mammals (exposed to an oral dose).

6 .2.2. Listed Species Occurrence Associated with Registered Use s

The screening

- level risk assessment for dicrotophos assumes that it may be applied nationwide, including U.S. territories and possessions. Therefore , no federally listed species are excluded from the screening level analyses, unless otherwise indicated ( e.g. , if only listed due to Similarity of Appearance to another listed species). A spatial co

- occurrence analysis that compares the best

available dat a regarding dicrotophos potential and documented use areas and listed species occurrence is needed to more explicitly address potential risk to listed species of concern.- Page 75 of 102

-



### 7

. References

Donley , D.E. 1967. Distribution of Bidrin in the Foliage of Treated Trees. Journal of Economic Entomology. 60(6): 1583

- 1585.

Engineering Toolbox. http://www.engineeringtoolbox.com/wood

- density

- d_40.html . Accessed December 7, 2012

Flickinger, E.L., D.H. White, C.A. Mitchell, and T.G. Lamont. 1984. Monocrotophos and dicrotophos residues in birds as a result of misuse of organophosphates in Matagorda County, Texas. J. Assoc. Off. Anal. Chem. 67:827

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Kuhns, M. 2012. Getting Chemicals into Trees without Spraying. Utah State University Cooperative Extension. NR/FF/020. http://extension.usu.edu/files/publications/publication/NR_FF_020pr.pdf

Martin, J.G.; B.D. Kloeppel, T.L. Schaefer, D.L. Kimbler, S.G. McNulty. 1998. Aboveground biomass and nitrogen allocation of ten deciduous southern Appalachian tree species.

Canadian Journal of Forest Research. 28: 1648

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Meyers, S.M. 1990. Effects of Northern Bobwhite ( Colinus virginianus ) Age and Weight on Results of the Avian Dietary Toxicity Test. Bulletin of Environmental Contamination and Toxicology. 45(5):66 7

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Mota

- Sanchez, D; B.M. Cregg, D.G. McCullough, T.M. Poland, R.M. Hollingworth. 2009.

Distribution of trunk

- injected 14 

### C

- imidacloprid in ash trees and effects on emerald ash borer (Coleoptera: Buprestidae) adults. Crop Protection 28: 655

- 661. http://naldc.nal.usda.gov/download/32582/PDF

Moser, VC. 2011. Age

- related differences in acute neurotoxicity produced by mevinphos, monocrotophos, dicrotophos, and phosphamidon. Neuroto xicology and Teratology. 33(4):451

- 45 7 . July

- August 2011.

United States Environmental Protection Agency (USEPA). 1993. Wildlife Exposure Factors

Handbook. EPA/600/R

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EPA/630/R

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### Process in the Office of Pesticide Programs, U.S. Environmental Protection Agency. Endangered and Threatened Species Effects Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C. January 23 , 2004.

U.S. Environmental Protection Agency. 2006. Reregistration Eligibility Decision for Dicrotophos, U.S. Environmental Protection Agency, Washington, D.C. 20460. Case no. 0145. July 2006.

U.S. Environmental Protection Agency. 2008 . Preli minar y Problem Formulation for Registration Review for Dicrotophos, U.S. Environmental Protection Agency, Washington, D .C. 20460. DP Barcode 348184. May 6, 2008

.

U.S. Environmental Protection Agency. 2010. User’s Guide: Screening Tool for Inhalation Risk

V ersion 1.0, U.S. Environmental Protection Agency, Washington, D.C. 20460. November 23, 2010.

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version 1.0 for use in the Environmental Fate and Effects Division. U .S. Environmental Protection Agency, Washington, D.C. 20460. July 6, 2010.

U.S. Environmental Protection Agency. 2012. White Paper in Support of the Proposed Risk Assessment Process for Bees. Office of Chemical Safety and Pollution Prevention,

Office of Pesticide Programs, Environmental Fate and Effects Division, Washington, D.C. September 11, 2012.

United States Fish and Wildlife Service (USFWS). 1980. Handbook of Acute Toxicity of Chemicals to Fish and Aquatic Invertebrates. Summaries of Toxicity T ests Conducted at Columbia National Fisheries Research Laboratory, 1965

- 78. Resource Publication 137. Washington, DC.

Willis, G.H. and L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of

Environmental Contamination and Toxicology 100: 23

- 73.- Page 77 of 102

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### 7 .1 Submitted Product Chemistry and Environmental Fate Studies

161

- 1 Hydrolysis (DICROTOPHOS)

MRID DOC NUM Citation Reference

39210 Brown, N.P.H.; Forster, A.S.; Furmidge, C.G.L. (1966) Stability of agricultural chemicals. Hydrolytic and thermal stabilities of phosphorylated crotonamides. Journal of the Science of Food and Agriculture 17(?/Nov):510

- 517. (Also~In~unpublished submission received Mar 18, 1980 under 6F1851; submitted by Shell Chemical Co., Washington, D.C.; CDL:099341

- U)

115287 Shell Chemical Co. (19??) Hydrolytic Decomposition of Bidrin. (Unpublished study received Oct 7, 1982 under 201

- 142; CDL:

248514

- C)

115288 Brown, N.; Forster, A.; Furmidge, C. (1966) Stability of agricul

tural chemicals. 1. Hydrolytic and thermal stabilities of phosphorylated crotonamides. J. Sci. Fd Agric. 17(11):510

- 517. (Also In unpublished submission received Oct 7, 1982 under 201

- 142; submitted by Shell Chemical Co., Washington, DC; CDL:

248514

- D)

160823 2031336 Stearns, S.; Lee, P. (1986) Aqueous Hydrolysis of [Carbon 14]

- SD

3562: RIR

- 22

- 002

- 86. Unpublished study prepared by Shell Agri

cultural Chemical Co. with summary of environmental fate data appended. 26 p.

161

- 2 Photodegradation

- water

MRID DOC NUM Citation Reference

160824 2031337 Stearns, S.; Lee, P. (1986) Aqueous Photolysis of [Carbon 14]

- SD

3562: RIR

- 22

- 003

- 86. Unpublished study prepared by Shell Agri

cultural Chemical Co. 20 p.

161

- 3 Photodegradation

- soil

MRID DOC NUM Citation Reference

87962 Shell Chemical Company (1964) ?Study of the Chemical SD 9129 and Bidrin^(R)I|. (Compilation; unpublished study received May 17, 1972 under 201

- 157; CDL:000875

- M)

115292 Osgerby, J.; Woodburn, A. (1965) The Adsorption and Decomposition of Bidrin and Azodrin in Soil: Project Progress Report PPR. FD 48/65. (Unpublished study received Oct 7, 1982

under 201

- 142; prepared by Shell Research, Ltd., Eng., submitted by Shell Chemic al Co., Washington, DC; CDL:248514

- J)- Page 78 of 102

-

115293 Osgerby, J.; Clarke, D. (1965) The Stability of Bidrin in Soil: Project Progress Report PPR. FD/5/65. (Unpublished study re

ceived Oct 7, 1982 under 201

- 142; prepared by Shell Research, Ltd., Eng., submitted by Shell Chemical Co., Washington, DC;
CDL:248514

- K)

160825 2031338 Powell, W.; Hernandez, H.; Lee, P. (1986) Soil Surface Photolysis of [Carbon 14]

- SD 3562: RIR

- 22

- 013

- 86. Unpublished study pre

pared by Shell Agricultural Chemical Co. 20 p.

161

- 4 Photodegradation

- air

MRID DOC NUM Citation Reference

28576 2031331 Hall, W.E.; Saliman, P.M. (1963) Sunlamp Stability of SD 9129 and Bidrin^(R)I Insecticide. (Unpublished study received Mar 18, 1980 under 6F1851; submitted by Shell Chemical Co., Washington, D.C.; CDL:099341

- M)

162

- 1 Aerobic soil metabolism

MRID DOC NUM Citation Reference

13470 2031328 Osgerby, J.M.; Clarke, D. (1965) Project Progress Report PPR FD/5/ 65: The Stability of Bidrin in Soil: Project F18. Includes method dated Feb 1, 1965. (Unpublished study received Jan 28,

1966 under 201

- 142; prepared by Shell Research, Ltd., submitted by S hell Chemical Co., Washington, D.C.; CDL:000834

- AM)

85766 Moore, C.A. (1971) The Degradation of Two Insecticides by Soil Microorganisms: ?Submitter| 33364. Masters' thesis, Mississippi State Univ., Dept. of Entomology. (Unpublished study received
Oct 21 , 1981 under 3125

- 306; submitted by Mobay Chemical Corp., Kansas City, Mo.; CDL:246088

- H)

115292 Progress report Osgerby, J.; Woodburn, A. (1965) The Adsorption and Decomposition of Bidrin and Azodrin in Soil: Project Progress Report PPR. FD 48/65. (Unpu blished study received Oct 7, 1982

under 201

- 142; prepared by Shell Research, Ltd., Eng., submitted by Shell Chemical Co., Washington, DC; CDL:248514

- J)

115293 Progress report Osgerby, J.; Clarke, D. (1965) The Stability of Bidrin in Soil: Project Progress Report PPR. FD/5/65. (Unpublished study re

ceived Oct 7, 1982 under 201

- 142; prepared by Shell Research, Ltd., Eng., submitted by Shell Chemical Co., Washington, DC;
CDL:2485 14

- K)

160826 2031339 Hernandez, H.; Stearns, S.; Lee, P. (1986) Aerobic Soil
Metabolism of SD 3562: RIR

- 22

- 006

- 86. Unpublished study prepared by Shell Agricultural Chemical Co. 26 p.

162

- 2 Anaerobic soil metabolism- Page 79 of 102

- MRID DOC NUM Citation Reference

160827 2031340 Hernandez, H.; Stearns, S.; Lee, P. (1986) Anaerobic Soil

Metabo

- lism of SD 3562: RIR

- 22

- 011

- 86. Unpublished study prepared by Shell Agricultural Chemical Co. 31 p.

163

- 1 Leach/adsorp/desorption

MRID DOC NUM Citation Reference

28571 Osgerby, J.M.; Woodburn, A.T. (1965) The Adsorption and Decomposi

- tion of Bidrin and Azodrin in Soil: PPR. FD 48/65. (Unpublished study received Mar 18, 1980 under 6F1851; prepared by Shell Re

- search, Ltd., submitted by Shell Chemical Co., Washington, D. C.; CDL:099341

- B)

87957
Same as 28571 Osgerby, J.M.; Woodburn, A.T. (1965) The Adsorption and Decomposi

- tion of Bidrin and Azodrin in Soil: PPR. FD 48/65. (Unpublished study received May 17, 1972 under 201

- 157; prepared by Shell Re

- search, Ltd., Engla nd, submitted by Shell Chemical Co., Washing

- ton, D.C.; CDL:000875

- B)

160828 2031341 Stearns, S.; Hernandez, H.; Lee, P. (1986) Soil Adsorption and

De

- sorption of SD 3562: RIR

- 22

- 001

- 86. Unpublished study prepared by Shell Agricultural Chemical Co. 32 p.

160829 2031342 Hernandez, H.; Stearns, S.; Lee, P. (1986) Soil Thin

- layer Mobility of SD 3562 and Its Soil Degradates: RIR

- 22

- 010

- 86. Unpublished study prepared by Shell Agricultural Chemical Co. 15 p.

163

- 2 Volatility

– lab

MRID DOC NUM Citation Reference

160825 Powell, W.; Hernandez, H.; Lee, P. (1986) Soil Surface Photolysis of [Carbon 14]

- SD 3562: RIR

- 22

- 013

- 86. Unpublished study pre

pared by Shell Agricultural Chemical Co. 20 p.

43500401 2031347 Atkins, R. (1994) Laboratory Volatility of ((carbon 13)/(carbon 14)) Dicrotophos: Lab Project Number: 837: 1635. Unpublished study prepared by PTRL East, Inc. 67 p.

164

- 1 Terrestrial field dissipation

MRID DOC NUM Citation Reference

115294 Compilation Shell Chemical Co. (1973) Bidrin Insecticide Soil Dissipation Data. (Compilation; unpublished study received Oct 7, 1982 under 201

- 142; CDL:248514

- L)

115295 2031334 Bosio, P.; Soulie, L. (1975) Pesticide Breakdown in Soil: Part 1:- Page 80 of 102

- Bidrin: Group Research Report BEGR.0101.75. (Unpublished study received Oct 7, 1982 under 201

- 142; prepared by Shell Chimie, Fr., submitted by Shell Chemical Co., Washington, DC;
CDL: 248514

- M)

41114301 2031346 Lee, P. (1989) Field Soil Dissipation Study with Dicrotophos: Pro

ject ID: AMR

- 1189

- 88. Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc., and En

- Cas Analytical Laborato

ries. 95 p.

165

- 1 Confined rotational crop

MRID DOC NUM Citation Reference

42210903 Nathan, E. (1992) Confined Accumulation Study of Dicrotophos on Rotational Crops: Lab Project Number: DICR/ENV 1. Unpublished study prepared by E. I. du Pont de Nemours and Co., Inc. 7 p.

44101001 O'Neal, S. (1996) A Confined Rotational Crop Study with (carbon 13)(carbon 14)

- Dicrotophos: Lab Project Number: 868: 1897. Unpublished study prepared by PTRL East, Inc. 199 p.

165

- 4 Bioaccumulation in fish

MRID DOC NUM Citation Reference

155661 2031335 Schultz, D.; Krudop, W. (1976) Bio

- accumulation of Azodrin

Insecticide in Fish

- Residue Levels of Azodrin and Two Metabolites (SD 12657 and SD 11319) in Rainbow Trout Resulting from the Exposure to 0.5 PPM Azodrin in Water:

Reference No. RI R

- 24

- 633

- 76

- A. Unpublished study prepared by Shell Develop

- ment Co. 13 p.

201

- 1 Droplet size spectrum

MRID DOC NUM Citation Reference

42210901 Mullin, L. (1992) Spray Drift Field Evaluation and Droplet Size Spectrum of Du Pont Bidrin Insecticide: Lab Project Number: DICR/ECO 1. Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc. 4 p.- Page 81 of 102

-



### 7 .2. Submitted Ecotoxicity Studies (Retrieved from OPPIN November 19, 2012)

71

- 1 Avian Single Dose Oral Toxicity

MRID Citation Reference

13438 Brown, V.K.; Ferrigan, L.W.; Stevenson, D.E. (1964) Technical Mem

- orandum:

Toxicological Investigations with Bidrin: Number Tox 31/64. (Unpublished study received Jan 28, 1966 under 201

- 142; prepared by Shell Research, Ltd., submitted by
Shell Chemical Co ., Washington, D.C.; CDL:000834

- D)

13439 Doyle, R.L.; Elsea, J.R. (1963) Toxicity Studies on Bidrin in Geese: N

- 279.

(Unpublished study received Jan 28, 1966 under 201

- 142; prepared by Hill Top Research Institute, Inc., sub

- mitted by Shell Chemical Co., Washington, D.C.;
CDL:000834

- E)

13707 Go ugh, B.J.; Shellenberger, T.E.; Escuriex, L.A. (1967?) Acute Tox

- icity of a Series

of Organophosphate Pesticides to Bobwhite and Japanese Quail. (Unpublished study received Sep 13, 1974 under 2724

- 169; prepared by Gulf South Research Institute,

submitted by Zoecon Industries, Inc., Dallas, Tex.; CDL:128306

- A)

98480 Grue, C.E. (1979) Response of common grackles to dietary concen

- trations of four

organophosphate pesticides. Taken from: Ab

- stracts: 49th Annual Meeting of the Cooper Ornithologic al Society; Jun 15

- 18, 1979. The Society. (Abstract no. 71; also~In~unpublished submission received Oct 26, 1979 under 476

- 2028; submitted by Stauffer Chemical Co., Richmond, Calif.; CDL:243641

- J)

102038 Hudson, R.; Tucker, R.; Haegele, M. (1972) Effect of age on sensi

- tivity: Acute oral

toxicity of 14 pesticides to mallard ducks of several ages. Toxicology and Applied Pharmacology (22):556

- 561. (Also In unpublished submission received Oct 26, 1977

under 1016

- 69; submitted by Union Carbide Corp., Arlington, VA; CDL:096397

- E)

5008363 Hudson, R.H.; Haegele, M.A.; Tucker, R.K. (1979) Acute oral and percutaneous

toxicity of pesticides to mallards: correlations with mammalian toxicity data. Toxicology and Ap plied Pharmacology 47(3):451

- 460.



### 71

- 2 Avian Dietary Toxicity

MRID Citation Reference

28592 Shellenberger, T.E.; Newell, G.W.; Adams, R.F.; et al. (1964?) Cholinesterase

Inhibition and Toxicological Evaluations of Two Organophosphate Pesticides in Japanese Quail. (Unpublished study received Mar 18, 1980 under 6F1851; prepared by Stanford Research Institute, Dept. of Toxicology, submitted by Shell Chemical Co., Washington, D.C.; CDL:099341

- AN)

63392 Shellenberger, T.E. (1967) Letter sent to Ralph F. Glasser dated Mar 28, 1967

?Toxicological evaluation of bobwhite and Japanese quail with Azodrin and Bidrin|. (Unpublished study received Jun 2, 1971 under 1F1062; prepared by Gulf South

Research Insti

- tu te, submitted by Shell Chemical Co., Washington, D.C.; CDL:

091826

- Q)

90901 Grue, C.E. (1979) Response of Common Grackles to Dietary Concentra

- tions of Four

Organophosphate Pesticides. (U.S. Fish and Wild

- life Service, Patuxent Wildlife
Research Center ; unpublished study; CDL:241307

- L)- Page 82 of 102

-

115300 Hill, E. (1981) Subacute dietary toxicities of dicrotophos and dieldrin in time

- replicated

trials with young ring

- necked pheasants and mallards. Avian and Mammalian Wildlife Toxicology 2:105

- 120. (Also In unpubli shed submission received Oct 7, 1982 under

201

- 142; submitted by Shell Chemical Co., Washington, DC; CDL:248514

- T)

115301 Hill, E.; Camardese, M. (1981) Subacute toxicity testing with young birds: Response

in relation to age and interest variability of L C50 estimates. Avian and Mammalian Wildlife Toxicology 2:41

- 65. (Also In unpublished submission received Oct 7, 1982

under 201

- 142; submitted by Shell Chemical Co., Washington, DC; CDL:248514

- U)

131892 Grue, C. (1982) Response of common grackles to dieta ry concentra

- tions of four

organophosphate pesticides. Archives of Environ

- mental Contamination and Toxicology 11:617

- 626. (Also In unpub

- lished submission received Sep 2, 1983

under 100

- 643; submitted by Ciba

- Geigy Corp., Greensboro, NC; CDL:251199

- D)



### 71

- 4 Avian Reproduction

MRID Citation Reference

28592 Shellenberger, T.E.; Newell, G.W.; Adams, R.F.; et al. (1964?) Cholinesterase

Inhibition and Toxicological Evaluations of Two Organophosphate Pesticides in Japanese Quail. (Unpublished study received Mar 18, 1980 under 6F1851; prepared by Stanford Research Institute, Dept. of Toxicology, submitted by Shell Chemical Co., Washington, D.C.; CDL:099341

- AN)

43871601 Wetherill, G. (1995) Draft Statistical Analysis of Data from A Reproduction Study in

Bobwhite Quail: Lab Project Number: AVC 5. Unpublished study prepared by Huntingdon Research Centre Ltd. 7 p.

43871602 Cameron, D. (1995) Effects of Dietary Administrati on of Dicrotophos on Reproduction

in the Mallard Duck: Status Report at Week 23: Lab Project Number: AVC 6. Unpublished study prepared by Huntingdon Research Centre Ltd. 16 p.

44005501 Cameron, D. (1996) Dicrotophos: Mallard Duck Dietary Reproduction and Preliminary

Studies: Lab Project Number: AVC 6: AVC 6/960138. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 259 p.

44005502 Cameron, D. (1996) Dicrotophos: Bobwhite Quail Dietary Reproduction and

Preliminary Studies: Lab Project Number: A VC 5: AVC 5/960137. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 313 p.



### 71

- 5 Simulated or Actual Field Testing

MRID Citation Reference

13439 Doyle, R.L.; Elsea, J.R. (1963) Toxicity Studies on Bidrin in Geese: N

- 279.

(Unpublished study received Jan 28, 1966 under 201

- 142; prepared by Hill Top Research Institute, Inc., sub

- mitted by Shell Chemical Co., Washington, D.C.;
CDL:000834

- E)

63393 Welch, J.F. (1968) Letter sent to Director, Bureau of Sport Fish

- eries & Wildlife dated

May 14, 1968: Bidrin

- wildlife relation

- ship investigations. (U.S. Fish & Wildlife Service, Denver Wildlife Research Center; unpublished study; CDL:130022

- C)

151814 Skelsey, J.; Boultinghouse, R. (1972) Wildlife Test (Bird Toxicity) Using Azodrin- Page 83 of 102

- Insecticide and Bidrin Insecticide. Unpublished study prepared by Shell Development Co. 7 p.

40873701 Palmer, D.; Krueger, H.; Jaber, M. (1988) Dicrotophos: An Evalua

- tion of its Effects

upon Wildlife on and around Cotton Fields in Southwestern Arizona: Wildlife International Ltd. Project No. 112

- 181. Unpublished study prepared by Wildlife International Ltd. 345 p.

40917001 Sheeley, D.; Dingledine, J.; Krueger, H.; et al (1988) Dicrotophos: An Evaluation of Its

Effects upon Wildlife on and Around Cotton Fields in Southeastern Alabama: Proj. No.

112

- 180; AMR 1246

- 88. Unpublished study prepared by Wildlife International Ltd. 326

p.



### 72

- 1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

13531 Henderson, C.; Pickering, Q.H.; Tarzwell, C.M. (1959) The Toxicity of Organic

Phosphorus and Chlorinated Hydrocarbon Insecticides to Fish: Report No. 4276. (Unpublished study received Mar 4, 1966 under unknown admin. no.; prepared by
U.S. Public Health Ser vice, Robert A. Taft Sanitary Engineering Center, submitted by Mobay Chemical Corp., Agricultural Div., Kansas City, Mo.; CDL:130685

- B)

63391 Cope, O.B. (1965) Letter sent to M.J. Sloan dated Nov 3, 1965 (Tox

- icity tests of

Bidrin on bluegill sunfish). (U.S. Fish and Wildlife Service, Fish

- Pesticide Research Laboratory; unpub

- lished study; CDL:091826

- M)

99910 McCann, J. (1970) ?Bidrin 8: Blu egill (Lepomis macrochirus)|: Test No. 276. (U.S.

Agricultural Research Service, Pesticides Regulation Div., Animal Biology Laboratory; unpublished study; CDL:132073

- A)



### 72

- 2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

13531 Henderson, C.; Pickering, Q.H.; Tarzwell, C.M. (1959) The Toxicity of Organic

Phosphorus and Chlorinated Hydrocarbon Insecticides to Fish: Report No. 4276. (Unpublished study received Mar 4, 1966 under unknown admin. no.; prepared by
U.S. Public Heal th Service, Robert A. Taft Sanitary Engineering Center, submitted by Mobay Chemical Corp., Agricultural Div., Kansas City, Mo.; CDL:130685

- B)

63391 Cope, O.B. (1965) Letter sent to M.J. Sloan dated Nov 3, 1965 (Tox

- icity tests of

Bidrin on bluegill sunf ish). (U.S. Fish and Wildlife Service, Fish

- Pesticide Research Laboratory; unpub

- lished study; CDL:091826

- M)

43787901 Davis, J.; Cunningham, F. (1995) Dicrotophos Technical: Acute Toxicity to the Water

Flea (Daphnia magna) Under Flow

- Through Test Condit ions: Lab Project Number: J9407001D. Unpublished study prepared by AMVAC Chemical Corp. and Toxicon Environmental Sciences. 56 p.



### 72

- 3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference- Page 84 of 102

-

43603305 Jones, F.; Davis, J. (1995) Dicrotophos Technical: Acute Toxicity to the Mysid

(Mysidopsis bahia) Under Flow

- Through Test Conditions: Lab Project Number: J9407001G. Unpublished study prepared by Toxikon Environmental Sciences. 48 p.

43603306 Jones, F.; Davis, J. (1995) Dicrotophos Technical: Acute Toxicity to the Sheepshead

Minnow (Cyprinodon variegatus) Under Flow

- Through Test Conditions: Lab Project Number: J9407001E. Unpublished study prepared by Toxikon Environmental Sciences. 48 p.

4373 9801 Cunningham, F.; Davis, J. (1995) Dicrotophos Technical: Acute Effect On New Shell

Growth of the Eastern Oyster (Crassostrea virginica): Lab Project Number: J9407001F: J9407001C. Unpublished study prepared by Toxikon Environmental Sciences. 50 p.



### 72

- 4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

13533 Farbenfabriken Bayer, Aktiengesellschaft (19??) Comparative Tests Determining Fish

Toxicity and Mosquito Effect Using Fish Species Lebistis reticulatus(Pet.) and Platypoecilus maculatus (Gue.) and Larvae of Aedes aegypti? L.: Report No. 5337. (Unpublished study received Mar 4, 1966 under unknown admin. no.; submitted by Mobay Chemical Corp., Agricultural Div., Kansas City, Mo.; CDL:130685

- D)

13819 Shell Chemical Company (1962) Toxicity of SD 3562 and SD 4294 to Fish

(?~Gambusia sp.~?). (Unpublished study including letter dated May 25, 1962 from E.T. White to W.R. Smith, received Jan 24, 1963 under 201

- 274; prepared in cooperation with Doctors Gamble Brothers and Archer Clinic; CDL:000970

- I)

43893901 Davis, J.; Cunningham, F. (1996) Dicrotophos Technical: Chronic Toxicity to the

Mysid (Mysidopsis bahia) Under Flow

- Through Conditions: Lab Project Number: J9407001H: J9503013. Unpublished study prepared by Toxikon Environmental Sciences. 88 p.

44956501 Hahne, R. (1999) Chronic Toxicity of Dicrotophos Techni cal

- During the Complete Life

Cycle of Daphnia magna Under Flow

- Through Test Condititons: Lab Project Number: 44978. Unpublished study prepared by ABC Laboratories, Inc. 46 p. {OPPTS 850.1300}



### 141

- 1 Honey bee acute contact

MRID Citation Reference

162751 Stevenson, J. (1968) Laboratory studies on the acute contact and oral toxicities of

insecticides to honeybees. Ann. appl. Biol. 61:467

- 472.



### 850.1400 Fish early

- life stage toxicity test

MRID Citation Reference

48037002 Habig, C. (2010) Dicrotophos: Request for a Waiver from Freshwater Fish Early Life

Stage Testing. Project Number: 0902870/000/E0T0/2010/001, 0902870/000/E0T0/0310/0001. Unpublished study prepared by Exponent, Inc. 7 p.- Page 85 of 102

-

48482901 Hicks, S. (2011) Dicrotophos Technica l: Early Life

- Stage Toxicity Test with the

Fathead Minnow, Pimephales promelas, under Flow

- Through Conditions. Project Number: 66150. Unpublished study prepared by ABC Laboratories, Inc. 80 p.



### 850.4100 Terrestrial plant toxicity, Tier 1 (seeding em ergence)

MRID Citation Reference

48037003 Habig, C. (2010) Dicrotophos: Request for a Waiver from Seedling Emergence and

Vegetative Vigor Testing. Project Number: 0902870/000/E0T0/2010/002, 0902870/000/E0T0/3010/0002. Unpublished study prepared by Exponent, Inc. 7 p.

48482902 Lee, B. (2011) Bidrin 8 Water Miscible Insecticide: Effects on the Seedling Emergence

and Growth of Non

- Target Terrestrial Plants (Tier I). Project Number: 66145. Unpublished study prepared by ABC Laboratories, Inc. 72 p.



### 850.4150 Terrestrial plant toxicity, Tier 1 (vegetative vigor)

MRID Citation Reference

48037003 Habig, C. (2010) Dicrotophos: Request for a Waiver from Seedling Emergence and

Vegetative Vigor Testing. Project Number: 0902870/000/E0T0/2010/002, 0902870/000/E0T0/3010/0002. Unpublished study prepared by Exponent, Inc. 7 p.

48482903 Lee, B. (2011) Bidrin 8 Water Miscible Insecticide: Effects on the Vegetative Vigor of

Non

- Target Terrestrial Plants (Tier 1). Project Number: 66146. Unpublished study prepared by ABC Laboratories, Inc. 69 p.



### 850.4400 Aquatic plant toxicity test using Lemna spp. Tiers I and II

MRID Citation Reference

48037001 Habig, C. (2010) Dicrotophos: Request for a Waiver from Aquatic Plant Testing.

Project Number: 0902870/000/E0T0/2010/003, 0902870/000/E0T0/0310/0003. Unpublished study prepared by Exponent, Inc. 7 p.

48443703 Rebstock, M. (2011) Dicrotophos: Growth Inhibition Test with the Freshwater Aquatic

Plant, Duckweed, Lemna gibba. Project Number: 66147, 800/AQU/006. Unpublished study prepared by ABC Laboratories, Inc. 69 p.



### 850.5400 Algal toxicity, Tiers 1 and II

MRID Citation Reference

48037001 Habig, C. (2010) Dicrotophos: Request for a Waiver from Aquatic Plant Testing.

Project Number: 0902870/000/E0T0/2010/003, 0902870/000/E0T0/0310/0003. Unpublished study prepared by Exponent, Inc. 7 p.

48443701 Rebstock, M. (2011) Dicrotophos: Static Growth Inhibition Test with the Marine

Diatom, Skeletonema costatum. Project Number: 66149, 800/AQU/0 04. Unpublished study prepared by ABC Laboratories, Inc. 64 p.- Page 86 of 102

-

48443702 Rebstock, M. (2011) Dicrotophos: Static Toxicity Test with the Green Alga,

Pseudokirchneriella subcapitata. Project Number: 66148, 800/AQU/005. Unpublished study prepared by ABC Labor atories, Inc. 65 p

.- Page 87 of 102

-



### Appendix A: PRZM/EXAMS output for highest cotton and tree injection scenarios

COTTON

stored as TXcotton.out
Chemical: dicrotophos

PRZM environment: TXcottonOP.txt modified Thuday, 14 June 2007 at 10:24:14

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 05:14:08

Metfile: w13958.dvf modified Tueday, 26 August 2008 at 05:14:44
Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 2.516 2.329 1.718 1.279

0.9903 0.2616

1962 2.619 2. 423 2.018 1.665

1.289 0.3387

1963 2.411 2.23 1.773 1.217

0.9238 0.2385

1964 2.597 2.405 1.815 1.344

1.037 0.2698

1965 17.57 16.6 13.02 7.447

5.427 1.415

1966 3.735 3.484 3.044 2.1

1.595 0.4197

1967 4.168 3.873 3.113 2.2

1.649 0.4289

1968 9.188 8.549 6.597 4.273

3.168 0.835

1969 4.288 3.996 3.207 2.146

1.597 0.4182

1970 17.05 15.97 12.37 6.948

5.045 1.316

1971 2.685 2.486 1.951 1.497

1.148 0.3019

1972 15.22 14.18 11.3 6.74

4.817 1.244

1973 3.22 2.998 2.524 1.996

1.543 0.4086

1974 4.467 4.125 3.39 2.255

1.653 0.4303

1975 8.157 7.743 5.752 3.912

2.963 0.7861

1976 7.266 6.822 6.279 5.305

3.991 1.04- Page 88 of 102

-



### 1977 3.449 3.204 2.804 2.385

1.786 0.4623

1978 8.543 7.893 6.362 4.208

3.023 0.7827

1979 19.76 18.52 14.02 8.329

6.262 1.653

1980 3.826 3.588 2.861 1.935

1.423 0.3721

1981 6.303 5.864 5.142 3.184

2.36 0.6205

1982 5.838 5.416 4.32 2.932

2.206 0.5706

1983 6.438 6.091 5.155 3.327

2.463 0.6511

1984 2.396 2.211 1.809 1.24

0.9408 0.2446

1985 2.456 2.273 1.672 1.236

0.9504 0.2482

1986 10.86 10.47 8.236 5.8

4.159 1.072

1987 2. 975 2.758 2.343 1.77

1.349 0.3602

1988 4.469 4.155 3.214 2.167

1.626 0.4266

1989 9.831 9.061 6.862 4.324

3.226 0.8406

1990 8.755 8.068 6.471 3.876

2.778 0.717

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.032258064516129 19.76 18.52 14.02 8.329

6.262 1.653

0.0645161290322581 17.57 16.6 13.02 7.447

5.427 1.415

0.0967741935483871 17.05 15.97 12.37 6.948

5.045 1.316

0.129032258064516 15.22 14.18 11.3 6.74

4.817 1.244

0.161290322580645 10.86 10.47 8.236 5.8

4.159 1.072

0.193548387096774 9.831 9 .061 6.862 5.305

3.991 1.04

0.225806451612903 9.188 8.549 6.597 4.324- Page 89 of 102

-



### 3.226 0.8406

0.258064516129032 8.755 8.068 6.471 4.273

3.168 0.835

0.290322580645161 8.543 7.893 6.362 4.208

3.023 0.7861

0.32258064516129 8.157 7.743 6.279 3.912

2.963 0.7827

0.354838709677419 7.266 6.822 5.752 3.876

2.778 0.717

0.387096774193548 6.438 6.091 5.155 3.327

2.463 0.6511

0.419354838709677 6.303 5.864 5.142 3.184

2.36 0.6205

0.451612903225806 5.838 5.416 4.32 2.932

2.206 0.5706

0.483870967741936 4.469 4.155 3.39 2.38 5

1.786 0.4623

0.516129032258065 4.467 4.125 3.214 2.255

1.653 0.4303

0.548387096774194 4.288 3.996 3.207 2.2

1.649 0.4289

0.580645161290323 4.168 3.873 3.113 2.167

1.626 0.4266

0.612903225806452 3.826 3.588 3.044 2.146

1.597 0.4197

0.645161290322581 3.735 3.484 2.861 2.1

1.595 0.4182

0.67741935483871 3.449 3.204 2.804 1.996

1.543 0.4086

0.709677419354839 3.22 2.998 2.524 1.935

1.423 0.3721

0.741935483870968 2.975 2.758 2.343 1.77

1.349 0.3602

0.774193548387097 2.685 2.486 2.018 1.665

1.289 0.3387

0.8064516 12903226 2.619 2.423 1.951 1.497

1.148 0.3019

0.838709677419355 2.597 2.405 1.815 1.344

1.037 0.2698

0.870967741935484 2.516 2.329 1.809 1.279

0.9903 0.2616

0.903225806451613 2.456 2.273 1.773 1.24

0.9504 0.2482

0.935483870967742 2.411 2.23 1.718 1.236

0.9 408 0.2446- Page 90 of 102

-



### 0.967741935483871 2.396 2.211 1.672 1.217

0.9238 0.2385

0.1 16.867 15.791 12.263 6.9272

5.0222 1.3088

Average of yearly averages: 0.639126666666667

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:
Output File: TXcotton

Metfile: w13958.dvf

PRZM scenario: TXcottonOP.txt

EXAMS environment file: pond298.exv

Chemical Name: dicrotophos
Description Variable Name Value Units

Comments
Molecular weight mwt 237.19 g/mol
Henry's Law Const. henry 3.13E

- 11 atm

- m^3/mol
Vapor Pressure vapr 7E

- 5 torr Solubility sol 11990 mg/L

Kd Kd 1.24 mg/L

Koc Koc mg/L
Photolysis half

- life kdp 0 days Half

life
Aerobic Aquatic Metabolism kbacw 17.4 days Halfife
Anaerobic Aquatic Metabolism kbacs 0 days Halfife

Aerobic Soil Metabolism asm 8.7 days Halfi fe
Hydrolysis: pH 7 990 days Half

life

Method: CAM 1 integer See

PRZM manual
Incorporation Depth: DEPI 0 cm Application Rate: TAPP 0.2242 kg/ha
Application Efficiency: APPEFF 0.95 fraction
Spray Drift DRFT 0.05 fraction of application rate applied to pond
Application Date Date 16

- 4 dd/mm or

dd/mmm or dd

- mm or dd

- mmm
Interval 1 interval 14 days Set to 0 or delete line for single app.
app. rate 1 apprate 0.5605 kg/ha

Interval 2 interval 14 days Set to 0- Page 91 of 102

-



### or delete line for single app.
app. rate 2 apprate 0.560 5 kg/ha

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5
Flag for Index Res. Run IR EPA Pond
Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

TREE INJECTION

stored as FLcitrus.out

Chemical: dicrotophos

PRZM environment: FLcitrusSTD.txt modified Tueday, 29 May 2007 at 12:45:56
EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 05:14:08

Metfile: w12844.dvf modified Tueday, 26 August 2008 at 05:14:22
Water segment concentrations ( ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 1.04 0.9764 0.7329 0.448

0.3241 0.0824

1962 1.534 1.416 1.042 0.6315

0.4555 0.116

1963 6.039 5.668 4.19 2.351

1.658 0.4186

1964 9.764 9.025 7.685 5.63

4.097 1.042

1965 0.8907 0.8266 0.6418 0.4133

0.317 7 0.08435

1966 1.089 1.004 0.8656 0.4982

0.3548 0.09032

1967 0.6773 0.623 0.5161 0.2942

0.2076 0.05286

1968 7.704 7.199 5.473 3.263

2.364 0.6136

1969 3.688 3.478 3.016 2.016

1.455 0.3724

1970 2.943 2.713 2.121 1.209

0.8513 0.2159

1971 6.843 6.335 4.538 2.519- Page 92 of 102

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### 1.849 0.4726

1972 6.413 5.93 4.417 3.107

2.257 0.5729

1973 2.158 1.967 1.398 1.072

0.8126 0.211

1974 1.474 1.356 0.9645 0.5847

0.4249 0.1088

1975 2.844 2.618 1.942 1.069

0.7712 0.1987

1976 11.94 11.25 8.242 4.631

3.389 0.8855

1977 8.17 7.708 5.674 4. 333

3.16 0.8092

1978 1.664 1.516 1.092 0.7439

0.5682 0.1495

1979 1.852 1.714 1.295 0.9563

0.7415 0.1951

1980 2.058 1.933 1.471 1.002

0.7355 0.1891

1981 5.576 5.124 3.618 1.963

1.401 0.3592

1982 1.704 1.58 1.336 1.011

0.756 0.1951

1983 2.419 2.218 1.616 0.8 657

0.6114 0.1559

1984 6.077 5.605 4.13 2.334

1.659 0.4199

1985 1.266 1.167 0.9541 0.6007

0.446 0.1156

1986 0.8556 0.7828 0.5874 0.3149

0.2432 0.06331

1987 4.849 4.465 3.227 1.88

1.344 0.3401

1988 6.376 5.908 4.49 3.549

2.62 0.6688

1989 0.08765 0.08312 0.0 5917

0.03765 0.02748 0.00848

1990 8.996 8.25 5.815 3.032

2.126 0.5409

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.032258064516129 11.94 11.25 8.242 5.63

4.097 1.042- Page 93 of 102

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### 0.0645161290322581 9.764 9.025 7.685 4.631

3.389 0.8855

0.09677419354838 71 8.996 8.25 5.815 4.333

3.16 0.8092

0.129032258064516 8.17 7.708 5.674 3.549

2.62 0.6688

0.161290322580645 7.704 7.199 5.473 3.263

2.364 0.6136

0.193548387096774 6.843 6.335 4.538 3.107

2.257 0.5729

0.225806451612903 6.413 5.93 4.49 3.032

2.126 0.5409

0.258064516129032 6.376 5.908 4.417 2.519

1.849 0.4726

0.290322580645161 6.077 5.668 4.19 2.351

1.659 0.4199

0.32258064516129 6.039 5.605 4.13 2.334

1.658 0.4186

0.354838709677419 5.576 5.124 3.618 2.016

1.455 0.3724

0.387096774193548 4.849 4.465 3.227 1.9 63

1.401 0.3592

0.419354838709677 3.688 3.478 3.016 1.88

1.344 0.3401

0.451612903225806 2.943 2.713 2.121 1.209

0.8513 0.2159

0.483870967741936 2.844 2.618 1.942 1.072

0.8126 0.211

0.516129032258065 2.419 2.218 1.616 1.069

0.7712 0.1987

0.548387096774194 2 .158 1.967 1.471 1.011

0.756 0.1951

0.580645161290323 2.058 1.933 1.398 1.002

0.7415 0.1951

0.612903225806452 1.852 1.714 1.336 0.9563

0.7355 0.1891

0.645161290322581 1.704 1.58 1.295 0.8657

0.6114 0.1559

0.67741935483871 1.664 1.516 1.092 0.7439

0.5682 0. 1495

0.709677419354839 1.534 1.416 1.042 0.6315

0.4555 0.116

0.741935483870968 1.474 1.356 0.9645 0.6007

0.446 0.1156

0.774193548387097 1.266 1.167 0.9541 0.5847

0.4249 0.1088- Page 94 of 102

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### 0.806451612903226 1.089 1.004 0.8656 0.4982

0.3548 0.09032

0.838709677419355 1.0 4 0.9764 0.7329 0.448

0.3241 0.08435

0.870967741935484 0.8907 0.8266 0.6418 0.4133

0.3177 0.0824

0.903225806451613 0.8556 0.7828 0.5874 0.3149

0.2432 0.06331

0.935483870967742 0.6773 0.623 0.5161 0.2942

0.2076 0.05286

0.967741935483871 0.08765 0.08312 0.05 917

0.03765 0.02748 0.00848

0.1 8.9134 8.1958 5.8009 4.2546

3.106 0.79516

Average of yearly averages: 0.324937333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:
Output File: FLcitrus

Metfile: w12844.dvf

PRZM scenario: FLcitrusSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: dicrotophos
Description Variable Name Value Units

Comments
Molecular weight mwt 237.19 g/mol
Henry's Law Const. henry 3.13E

- 11 atm

- m^3/mol
Vapor Pressure vapr 7E

- 5 torr Solubility sol 11990 mg/L

Kd Kd 1.24 mg/L

Koc Koc mg/L
Photolysis half

- life kdp 0 days Half

life
Aerobic Aquatic Metabolism kbacw 17.4 days Halfife
Anaerobic Aquatic Metabolism kbacs 0 days Halfife

Aerobic Soil Metabolism asm 8.7 days Halfife
Hydrolysis: pH 7 990 days Half

l ife

Method: CAM 1 integer See

PRZM manual
Incorporation Depth: DEPI 0 cm- Page 95 of 102

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### Application Rate: TAPP 0.2556 kg/ha
Application Efficiency: APPEFF 1.0 fraction
Spray Drift DRFT 0.0 fraction of application rate applied to pond
Application Date Date 29

- 4 dd/mm or

d d/mmm or dd

- mm or dd

- mmm
Interval 1 interval 14 days Set to 0 or delete line for single app.
app. rate 1 apprate 0.2556 kg/ha

Interval 2 interval 14 days Set to 0 or delete line for single app.
app. rate 2 apprate 0.2556 kg/ha

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5
Flag for Index Res. Run IR EPA Pond
Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)- Page 96 of 102

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### Appendix B : Toxicity Categories and Levels of Concern

Table B1

. Categories of Toxicity for Aquatic Organisms

L C 50 ( p pm) Toxici t y C a t e go r y

< 0

. 1 Very hi g h ly t o xic

> 0

. 1

- 1 Hi g h ly toxic

> 1

- 10 M od e rately t o xic

> 1 0

- 1 0 0 Slightly toxic

> 1 00 Practically n on toxic



### Table B2. Categories of Toxicity for Te r res t rial Organisms

Oral d o se LD 5 0 ( m g/k g

- b w ) Toxici t y C a t e go r y

< 10 Very h ig h ly to x ic

10

- 5 0 Hi g h ly toxic

5 1

- 500 M od e rately t o xic

5 0 1

- 2 0 0 0 Slightly toxic

> 2 0 00 Practically n ont ox ic

Die t ary L C 50 (ppm) Toxici t y C a t e go r y

< 50 Very h ig h ly to x ic

5 0

- 500 H i g h ly t ox i c

5 0 1

- 1 0 0 0 M od e rately t o x ic

1 00 1

- 5 00 0 Slightly toxic

> 5 0 00 Practically n ont ox ic



### Table B3. Categories of Toxicity for Honey Bee

Bee A c ute Contact L D 50 (μg / bee) Toxici t y C a t e go r y
<2 Hig h ly t ox ic

2

– 1 0

. 9 9 M od e rately t o x ic

> 11 Practically nontoxic



### Table B4. Levels of Concern for Te rr estrial and Aquatic Organisms

T a xa Acu t e L O C Ch r o nic L O C

Avi a n 1 (t e rres t

rial p h ase a m

phibia n s) 0

. 1 1

M a m m a lia n 2 0

. 1 1

Terres t rial pla n ts 3 1 Aq u atic A n i m a ls 4 (aq u atic phase

a m phibia n s) 0

. 05 1

Insects 5 0

. 05 1

Used in RQ ca lc ulations:

1 L D 50 and es t i m a ted NOEL

2 L D 50 and NOEC

3 EC25

4 LC / EC 50 and estimated and r e p roducti v e NOEC

5 L D 50 p e r EF E D’s CRLF Steer i ng Co mm ittee- Page 97 of 102

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### Appendix C : Example T

- REX (v. 1.5) Input and Output for Dicrotophos

Table C .1. T

- REX Model Inputs: Chemical Application Scenarios and Body Mass for Assessed Species.- Page 98 of 102

-



### Table C.2. Avian and Mammalian Toxicity Endpoints for RQ Calculation.- Page 99 of 102

-



### Appendix D : STIR Results- Page 100 of 102

-



### Appendix E : SIP Results- Page 101 of 102

-

A ppe nd i x F : A cce p t ed E C O T O X D a t a Ta b l e

T h e c od e li st f

o r E C O T O X can b e f

oun d a t : htt p :// c f p u b

. e p a .gov/ ec otox/ b l ac k b ox/h e l p / c od e li s t. p df

C he m i cal N a m e R ef # Genus S pec i es C o mm on N a m e Eff ect G r oup Eff ect M eas E ndp t 1 E ndp t 2 D ur P r e f e rr ed M ean D ur U n i t P r e f e rr ed C onc #1 Au t hor R epo r t ed M ean C onc #1 P u r it y Adjus t ed i n P r e f e rr ed U n i t

M ean C onc #2 P u r it y Adjus t ed i n P r e f e rr ed U n i t

M ean C onc U n it s P r e f e rr ed % P u r ity

D i c r o t ophos 112447 C aeno r habd iti s e l egans N e m a t ode BE H BE H N M VM E C50 0

. 208333333 d 1

. 11 1

. 11 m M 100

D i c r o t ophos 112447 C aeno r habd iti s e l egans N e m a t ode M OR M OR M O R T L C50 0

. 166666667 d 35

. 03 35

. 03 m M 100

D i c r o t ophos 25114 C a r i ca papa y a P apa y a G R O G R O H G H T LOA E L 28 d 0

. 062 0

. 062 AI % 100

D i c r o t ophos 25114 C a r i ca papa y a P apa y a G R O G R O H G H T N OA EL 28 d 0

. 031 0

. 031 AI % 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D LOA E L 30

. 44 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp PHY I MM P A RA LOA E L 30

. 44 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D N OA EL 336 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D LOA E L 60

. 88 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D LOA E L 60

. 88 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D N OA EL 60

. 88 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D N OA EL 60

. 88 d 2 2 m l 100

D i c r o t ophos 87491 C a lli r h y ti s co r n i ge r a P a r as iti c Wasp P OP P OP A BN D N OA EL 60

. 88 d 2 2 m l 100

D i c r o t ophos 93416 M i c r op liti s c r oce i pes B r acon i d P a r as it o i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 93416 M i c r op liti s c r oce i pes B r acon i d P a r as it o i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 93416 C a r d i och il es n i g r i ceps B r acon i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 93416 C a r d i och il es n i g r i ceps B r acon i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 114809 H y pe r a pos ti ca Weev i l P OP P OP A BN D LOA E L 21 d 1 1 AI l b / ac r e 100

D i c r o t ophos 98221 Cry p t o l ae m us m on t r ouz i e r i M ea l y bug D es t r o y er M OR M OR M O R T L T 50 1 d 0

. 0477 0

. 0477 AI % w / w 100

D i c r o t ophos 98221 Cry p t o l ae m us m on t r ouz i e r i M ea l y bug D es t r o y er M OR M OR M O R T L T 50 1 d 0

. 477 0

. 477 AI % w / w 100

D i c r o t ophos 98221 M e t aph y cus l u t eo l us B r own S ca l e P a r as it e M OR M OR M O R T L T 50 1 d 0

. 0477 0

. 0477 AI % w / w 100

D i c r o t ophos 98221 M e t aph y cus l u t eo l us B r own S ca l e P a r as it e M OR M OR M O R T L T 50 1 d 0

. 477 0

. 477 AI % w / w 100

D i c r o t ophos 98221 Aph y ti s m e li nus R ed S ca l e P a r as it e M OR M OR M O R T L T 50 1 d 0

. 0477 0

. 0477 AI % w / w 100

D i c r o t ophos 98221 Aph y ti s m e li nus R ed S ca l e P a r as it e M OR M OR M O R T L T 50 1 d 0

. 477 0

. 477 AI % w / w 100

D i c r o t ophos 98221 L i ndo r us l oph a n t hae Bl ack Lady B ee tl e M OR M OR M O R T L T 50 1 d 0

. 0477 0

. 0477 AI % w / w 100

D i c r o t ophos 98221 L i ndo r us l oph a n t hae Bl ack Lady B ee tl e M OR M OR M O R T L T 50 1 d 0

. 477 0

. 477 AI % w / w 100

D i c r o t ophos 88810 NR T h y sanop t e r a T h r i p O r der P OP P OP A BN D N OA EL 6 d 0

. 2 0

. 2 AI l b / ac r e 100

D i c r o t ophos 79345 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL 173 d 0

. 1 0

. 1 AI l b / ac r e 100

D i c r o t ophos 79345 Fr an k li n i e ll a f usca T obacco T h r i p P OP P OP A BN D LOA E L 7 d 0

. 1 0

. 1 AI l b / ac r e 100

D i c r o t ophos 88060 Fr an k li n i e ll a sp. C o mm on T h r i p P OP P OP A BN D N OA EL 5 d 0

. 33 0

. 33 AI l b / ac r e 100

D i c r o t ophos 88060 Fr an k li n i e ll a sp. C o mm on T h r i p P OP P OP A BN D LOA E L 5 d 0

. 33 0

. 33 AI l b / ac r e 100

D i c r o t ophos 88060 Fr an k li n i e ll a sp. C o mm on T h r i p P OP P OP A BN D N OA EL 2 d 0

. 33 0

. 33 AI l b / ac r e 100

D i c r o t ophos 88060 Fr an k li n i e ll a sp. C o mm on T h r i p P OP P OP A BN D N OA EL 2 d 0

. 33 0

. 33 AI l b / ac r e 100

D i c r o t ophos 101655 NR P en t a t o m i dae S ti nk B ug F a m il y P OP P OP A BN D N OA EL gs 8 8 f l oz / ac r e 100

D i c r o t ophos 101655 NR P en t a t o m i dae S ti nk B ug F a m il y P OP P OP A BN D LOA E L gs 8 8 f l oz / ac r e 100

D i c r o t ophos 101655 NR P en t a t o m i dae S ti nk B ug F a m il y P OP P OP A BN D N OA EL gs 8 8 f l oz / ac r e 100

D i c r o t ophos 101655 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL hv 8 8 f l oz / ac r e 100

D i c r o t ophos 101655 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL hv 8 8 f l oz / ac r e 100

D i c r o t ophos 101655 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL hv 8 8 f l oz / ac r e 100

D i c r o t ophos 64843 Ga ll us do m es ti cus D o m es ti c C h i c k en B CM ENZ A C H E I C50 7 d 55 55 ppm 100

D i c r o t ophos 64843 Ga ll us do m es ti cus D o m es ti c C h i c k en M OR M OR M O R T L D5 0 7 d 7

. 97 7

. 97 ppm 100

D i c r o t ophos 64843 Ga ll us do m es ti cus D o m es ti c C h i c k en B CM ENZ C E ST I C50 7 d 55 55 ppm 100

D i c r o t ophos 150470 Goss y p i um h i r su t um C o tt on G R O G R O H G H T LOA E L 23 d 0

. 25 0

. 25 AI l b / ac r e 100

D i c r o t ophos 150470 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL hv 0

. 25 0

. 25 AI l b / ac r e 100

D i c r o t ophos 150470 NR T h r i p i dae T h r i p F a m il y P OP P OP A BN D LOA E L 8 d 0

. 25 0

. 25 AI l b / ac r e 100

D i c r o t ophos 101406 L i paph i s e ry s i m i T u r n i p Aph i d M OR M OR M O R T NR

- L ET H 8 d 0

. 24 0

. 24 % 100

D i c r o t ophos 101406 D i ae r e ti e ll a r apae P a r as it o i d Wasp G R O D V P E M R G LOA E L 8 d 0

. 24 0

. 24 % 100

D i c r o t ophos 29481 O ry za sa ti va Ri ce P OP P OP B M AS N OA EL hv 2

. 5 2

. 23 l b / ac r e 100

D i c r o t ophos 29481 O ry za sa ti va Ri ce P OP P OP B M AS N OA EL hv 2

. 5 2

. 23 l b / ac r e 100

D i c r o t ophos 29481 O ry za sa ti va Ri ce G R O G R O H G H T N OA EL hv 0

. 3 0

. 3 % 100

D i c r o t ophos 29481 O ry za sa ti va Ri ce G R O M P H LG T H N OA EL hv 0

. 3 0

. 255 % 85

D i c r o t ophos 29481 O ry za sa ti va Ri ce G R O G R O N L EF N OA EL hv 0

. 3 0

. 255 % 85

D i c r o t ophos 96420 Ap i s m e llif e r a H oney B ee M OR M OR M O R T L D5 0 1 d 0

. 076 0

. 076 ug 100

D i c r o t ophos 96420 Ap i s m e llif e r a H oney B ee M OR M OR M O R T L D9 0 1 d 0

. 1 0

. 1 ug 100

D i c r o t ophos 96420 Ap i s m e llif e r a H oney B ee M OR M OR M O R T L D5 0 1 d 0

. 068 0

. 068 ug 100

D i c r o t ophos 96420 Ap i s m e llif e r a H oney B ee M OR M OR M O R T L D9 0 1 d 0

. 2 0

. 2 ug 100

D i c r o t ophos 88074 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D LOA E L 2 d 0

. 3 0

. 3 AI l b / ac r e 100

D i c r o t ophos 88074 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D LOA E L 3 d 0

. 4 0

. 4 AI l b / ac r e 41

D i c r o t ophos 88074 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D LOA E L 3 d 0

. 4 0

. 4 AI l b / ac r e 100

D i c r o t ophos 88773 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D N OA EL 30 d 0

. 2 0

. 2 AI l b / ac r e 100

D i c r o t ophos 88773 Goss y p i um h i r su t um C o tt on P OP P OP B M AS N OA EL hv 0

. 2 0

. 2 AI l b / ac r e 100

D i c r o t ophos 88773 Goss y p i um h i r su t um C o tt on G R O G R O GG R O N OA EL hv 0

. 2 0

. 2 AI l b / ac r e 100

D i c r o t ophos 88773 NR T h r i p i dae T h r i p F a m il y P OP P OP A BN D LOA E L 7 d 0

. 2 0

. 2 AI l b / ac r e 100

D i c r o t ophos 156321 N eoz y g it es f r esen i i F ungus P OP P OP A BN D N OA EL 20 d 0

. 56 0

. 49952 l b / ac r e 100

D i c r o t ophos 156321 N eoz y g it es f r esen i i F ungus P OP P OP A BN D N OA EL 20 d 0

. 56 0

. 49952 l b / ac r e 100

D i c r o t ophos 156321 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D N OA EL 20 d 0

. 56 0

. 56 AI k g / ha 100

D i c r o t ophos 156321 Aph i s goss y p i i C o tt on Aph i d P OP P OP A BN D N OA EL 20 d 0

. 56 0

. 56 AI k g / ha 100

D i c r o t ophos 154178 H y po t hene m us ha m pei C o ff ee B o r er B ee tl e M OR M OR M O R T L C50 1

. 083333333 d 0

. 039114 0

. 039114 AI % 100

D i c r o t ophos 154178 H y po t hene m us ha m pei C o ff ee B o r er B ee tl e M OR M OR M O R T L C50 1

. 083333333 d 0

. 00998 0

. 00998 AI % 100

D i c r o t ophos 50386 Anas p l a t yr h y nchos M a ll a r d D uck M OR M OR M O R T LOA E L 30 d 0

. 25 0

. 25 m g / k g bd w t 98

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 20 18 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 7 d 12

. 5 11

. 25 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 28 25

. 2 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 7 d 18

. 7 16

. 83 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 40 36 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 15

. 8 14

. 22 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 56 50

. 4 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 27 24

. 3 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 30

. 8 27

. 72 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- ZERO 8 d 20 18 ppm 90- Page 102 of 102

- C he m i cal N a m e R ef # Genus S pec i es C o mm on N a m e Eff ect G r oup Eff ect M eas E ndp t 1 E ndp t 2 D ur P r e f e rr ed M ean D ur U n i t P r e f e rr ed C onc #1 Au t hor R epo r t ed M ean C onc #1 P u r it y Adjus t ed i n P r e f e rr ed U n i t

M ean C onc #2 P u r it y Adjus t ed i n P r e f e rr ed U n i t

M ean C onc U n it s P r e f e rr ed % P u r ity

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 56 50

. 4 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- ZERO 8 d 20 18 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T NR

- L ET H 8 d 56 50

. 4 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 29

. 9 26

. 91 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 14 12

. 6 ppm 90

D i c r o t ophos 39755 C o li nus v i r g i n i anus N o r t he r n B obwh it e Q ua i l M OR M OR M O R T L C50 8 d 29 26

. 1 ppm 90

D i c r o t ophos 50181 C o t u r n i x japon i ca Japanese Q ua i l BE H FD B FC N S LOA E L 1 d 26 26 ppm 85

D i c r o t ophos 50181 C o t u r n i x japon i ca Japanese Q ua i l BE H FD B FC N S LOA E L 2 d 26 26 ppm 85

D i c r o t ophos 50181 C o t u r n i x japon i ca Japanese Q ua i l BE H FD B FC N S LOA E L 3 d 26 26 ppm 85

D i c r o t ophos 50181 C o t u r n i x japon i ca Japanese Q ua i l BE H FD B FC N S LOA E L 4 d 26 26 ppm 85

D i c r o t ophos 50181 C o t u r n i x japon i ca Japanese Q ua i l BE H FD B FC N S LOA E L 5 d 26 26 ppm 85

D i c r o t ophos 63269 NR A r achn i da S p i de r / M it e C l ass P OP P OP A BN D N OA EL 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 63269 Geoco r i s sp. Bi g

- E y e B ug P OP P OP A BN D N OA EL 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 63269 Geoco r i s sp. Bi g

- E y e B ug P OP P OP A BN D N OA EL 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 63269 O r i us i ns i d i osus M i nu t e Pi r a t e B ug P OP P OP A BN D LOA E L 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 63269 O r i us i ns i d i osus M i nu t e Pi r a t e B ug P OP P OP A BN D N OA EL 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 63269 NR A r achn i da S p i de r / M it e C l ass P OP P OP A BN D N OA EL 14 d 0

. 45 0

. 45 AI k g / ha 100

D i c r o t ophos 153435 NR C i cade lli dae Lea f hopper F a m il y P OP P OP A BN D LOA E L 70 d 0

. 1 0

. 1 % 100

D i c r o t ophos 153435 NR C i cade lli dae Lea f hopper F a m il y P OP P OP A BN D N OA EL 70 d 0

. 1 0

. 1 % 100

D i c r o t ophos 153435 NR Lep i dop t e r a M o t h And B u tt e r fl y O r der P OP P OP A BN D LOA E L 70 d 0

. 1 0

. 1 % 100

D i c r o t ophos 153435 Goss y p i um sp. C o tt on RE P RE P S EP D N OA EL 70 d 0

. 1 0

. 1 % 100

D i c r o t ophos 153435 Goss y p i um sp. C o tt on P OP P OP B M AS N OA EL 70 d 0

. 1 0

. 1 % 100

D i c r o t ophos 114803 S o r ghum b i co l or ssp. b i co l or G r a i n S o r ghum P OP P OP B M AS N OA EL hv 0

. 5 0

. 5 AI l b / ac r e 100

D i c r o t ophos 114803 S o r ghum b i co l or ssp. b i co l or G r a i n S o r ghum P OP P OP B M AS N OA EL hv 0

. 5 0

. 5 AI l b / ac r e 100

D i c r o t ophos 36627 Anas p l a t yr h y nchos M a ll a r d D uck M OR M OR M O R T NR

- ZERO 14 d 32 32 ppm 85

D i c r o t ophos 36627 Anas p l a t yr h y nchos M a ll a r d D uck M OR M OR M O R T NR

- ZERO 0

. 75 d 2

. 4 2

. 4 m g / k g bd w t 85

D i c r o t ophos 36627 Anas p l a t yr h y nchos M a ll a r d D uck M OR M OR M O R T NR

- ZERO 40 d 16 16 ppm 85

D i c r o t ophos 155866 M i c r op liti s c r oce i pes B r acon i d P a r as it o i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 155866 M i c r op liti s c r oce i pes B r acon i d P a r as it o i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 155866 C a r d i och il es n i g r i ceps B r acon i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 155866 C a r d i och il es n i g r i ceps B r acon i d Wasp M OR M OR M O R T NR

- L ET H 1 d 0

. 28 0

. 28 AI k g / ha 100

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at BE H BE H N M VM N OA EL LOA E L d 1

. 06 1

. 0494 2

. 1087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 749 0

. 74151 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 447 0

. 44253 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at BE H BE H N M VM E D5 0 d 1

. 58 1

. 5642 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST LOA E L d 0

. 213 0

. 21087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST LOA E L d 0

. 213 0

. 21087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST LOA E L d 0

. 213 0

. 21087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST LOA E L d 0

. 213 0

. 21087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at BE H BE H N M VM N OA EL LOA E L d 0

. 213 0

. 21087 1

. 0494 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 314 0

. 31086 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 36 0

. 3564 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at BE H BE H N M VM E D5 0 d 1

. 21 1

. 1979 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST LOA E L d 0

. 107 0

. 10593 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST N OA EL LOA E L d 0

. 107 0

. 10593 0

. 21087 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 431 0

. 42669 m g / k g bd w t 99

D i c r o t ophos 155867 R a tt us no r veg i cus N o r way R at B CM ENZ C E ST E D5 0 d 0

. 403 0

. 39897 m g / k g bd w t 99

D i c r o t ophos 105685 C o t u r n i x japon i ca Japanese Q ua i l B CM ENZ C E ST LOA E L 0

. 041666667 d 3 3 m g / k g bd w t 85

D i c r o t ophos 105685 C o t u r n i x japon i ca Japanese Q ua i l B CM ENZ C E ST LOA E L 0

. 041666667 d 3 3 m g / k g bd w t 85

D i c r o t ophos 105685 C o t u r n i x japon i ca Japanese Q ua i l B CM ENZ C E ST LOA E L 0

. 041666667 d 3 3 m g / k g bd w t 85

D i c r o t ophos 105685 C o t u r n i x japon i ca Japanese Q ua i l B CM ENZ C E ST LOA E L 0

. 041666667 d 3 3 m g / k g bd w t 85

D i c r o t ophos 67192 M egach il e r o t und a t a A lf a lf a Lea f cu tt er B ee M OR M OR M O R T L D5 0 1 d 1

. 2 1

. 2 ppm 82