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## UNITED STATES ENVIRONMENTAL PROTECTION A(aENCY p i , W 

## $ < WASHINGTON, D.C. 20460 ~T

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~ G,C OFFICE OF CHEMICAL SAFETY ANO POLLUTION PREVENTION 

## September 10, 2014 PC Code: 082583 

## MEMORANDUM DP Bareode: 418273 SUBJECT: Preliminary Ecological Risk Assessment for Registration Review of cyhalofop-butyl FROM: Kristina Garber, Senior Biologist

Richard Shamblen, Chemist ER132/EFED (7507P) RICHARDSHAMBLEN 2014.09.11 09:09:58 - 4'00' 

## THROUGH: Brian Anderson, Branch Chief

ERB2/EFED (7507P) TO: Jolene Trujillo, Chemical Review Manager

Linda Arrington, Branch Chief RMIBV/PRD (7508P) This memorandum transmits the problem formulation and preliminary ecological risk assessment for the registration review of the herbicide cyhalofop-butyl. A preliminary risk assessment was conducted at the problem formulation stage because the current database was sufficient to support an ecological risk assessment. Based on currently registered uses and labeled rates, this preliminary assessment identifies potential risks to non-target organisms. This assessment is focused on species that are not federally listed as threatened or endangered (referred to as "listed"); however, some general discussion of taxa of listed species for which "no effect" determinations are expected is included in this assessment. For taxa where there may be risk, specific determinations for listed species are considered uncertain at this time. Currently labeled rates of cyhalofop-butyl have the potential to cause adverse effects, i.e., pose risk, to non-target grasses (located adjacent to rice paddies). There is also potential for chronic effects to mammals feeding within treated fields as well as potential mortality to fish and invertebrates located within a rice paddy on the day of the application. The distance from treated areas potentially affected may be reduced by use of larger droplet spectrum or other spray drift reduction technology. Section 2.3 addresses ambiguous label language

- that could be revised to reduce conservative assumptions used in assessing potential risks. Respective risk and degree of risk certainty for each major taxonomic group assessed are illustrated below. Placement was based on risk calculations, fate characteristics, incident reports, completeness of data set and other factors considered and detailed in the following ecological risk assessment.

Page 1 of 48

# Taxa at Risk From Registered Cyhalophop Uses

Aquatic plants Terrestrial plants

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## Mammals

Terrestrial invertebrates Aquatic animals



# Risk

Page 2 of 48

# Ecological Risk Assessment for the Registration Review of Cyhalofop-butyl IUPAC name : Butyl-(R)-2-[4(4-cyano-2-fluorophenoxy) phenoxy]propionate



# CAS Number: 122008-85-9 USEPA PC CODE: 082583

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# 0 Prepared by: Kristina Garber, MS, Senior Science Advisor Richard Shamblen, Chemist Reviewed by: Melanie Biscoe, MEM, Physical Scientist (Review Panel) Nick Federoff, Ph.D., Wildlife Biologist Jean Holmes, DVM, MPH, Risk Assessment Process Leader James Lin, Ph.D., Environmental Engineer Keith Sappington, MS, Senior Science Advisor (Review Panel) Approved by: 

## Brian Anderson, MEM, Branch Chief, Environmental Risk Branch 11

Environmental Fate and Effects Division Office of Pesticide Programs U.S. Environmental Protection Agency 1200 Pennsylvania Avenue, NW Washington, D.C. 20460
September 10, 2014

Page 3 of 48

# Table of Contents

l

. 

## Executive Summary ..............................................................................................................5

2. 

## Problem Formulation ............................................................................................................8 2.1. Mode of Action ......................................................................................................... 8 2.2. Use Characterization .................................................................................................8 2.3. Label Uncertainties .................................................................................................11 2.4. Previous Risk Assessments .....................................................................................12 2.5. Water Quality ..........................................................................................................12 2.6. Stressors of Concern ...............................................................................................13 2.7. Analysis plan ........................................................................................................... 14

3. 

## Exposure Analysis ..............................................................................................................18 3.1. Environmental Fate and Transport Summary .........................................................18 3.2. Estimated exposure .................................................................................................20 3.2.1. Direct Deposition onto terrestrial Food Items (located on treated paddies) ...........20 3.2.3. Spray Drift Transport ..............................................................................................23

4. 

## Effects Analysis ..................................................................................................................25 4.1. Toxicity data ...........................................................................................................25 4.2. Reported Ecological Incidents ................................................................................29 4.3. Endocrine Disruptor Screening Program ................................................................29 5. Risk Estimation and Characterization .................................................................................30 5.1. TerrestrialOrganisms ..............................................................................................30 5.1.1. Animals .......................................................................................................30 5.1.2. Plants .............................................................................................................32 5.2. Aquatic Organisms ..................................................................................................33 5.3. Listed Species .........................................................................................................33 5.4. Risk Conclusions ....................................................................................................34

6. 

## Literature Cited ...................................................................................................................35

Page 4 of 48

## 1. Executive Summary



## Initially registered in the United States in 2002, cyhatofop-butyl is a post-emergent herbicide for the selective control of grass weeds in the production of rice. Cyhalofop-butyl is registered for use in nine states, including Arkansas, California, Florida, Louisiana, Mississippi, Missouri, Tennessee, and Texas. Currently, there are 14 registrations for liquid and granular formulated products, including two Special Local Needs supplemental labels. The herbicide may be applied via ground or aerial broadcast to dry and wet seeded rice paddies. With maximum application rates of up to 0.29 lb a.i./A, sequential applications may be made with total seasonal rates of 0.47 lb a.i./A. Two granular formulated supplemental labels allow for only a single application at a maximum rate of 0.361b a.i./A/ season. For this ecological risk assessment, degradates of cyhalofop-butyl were determined to not be of concern to aquatic organisms and terrestrial vertebrates. However, cyhalofop-acid appears to be of comparable toxicity to the parent to terrestrial plants. Cyhalofop-butyl is slightly mobile, with an organic carbon partition coefficient (K oc ) of 2892 — 7960 1/kg, and is slightly soluble at 0.44 mg/L. With a calculated Henry's law constant of 9.4 x 10' 9 atm-m 3 /mole, the herbicide is not likely tovolatilize. Although it has a log Kow of 3.3, a fish bioconcentration study indicates that cyhalofopbutyl does not significantly bioconcentrate. Cyhalofop-butyl degrades by b io logical ly-med iated hydrolysis to cyhalofop-acid in less than a day. Further degradation leads to cyhalofop-amide and to cyhalofop-diacid. Abiotic hydrolysis and photolysis are much slower compared to biological degradation at neutral to acidic pH. The major degradates (acid, amide, diacid) are generally water-soluble and acidic. The K oe for cyhalofop-acid is about 60 mL/g. Field study results indicated that residues in rice paddy water dissipated to below detectable levels after 28 days. The modified Tier 1 Rice Model was used to model various registered product application scenarios to estimate environmental concentrations (EECs). Results indicate that California's Special Local Need supplemental labels for Clincher ® GR and Clincher ® Granule yield the highest peak concentration of 363 ,ug/L. Both supplemental labels allow for a single maximum application rate of 0.36 lbs a.i./A per event annually. These supplemental labels will expire in August 2015. Available toxicity data indicate that cyhalofop-butyl is practically non-toxic to mammals, birds, and bees on an acute exposure basis. Available chronic toxicity data with mammals and birds indicate no effects to reproduction or offspring at 100 mg/kg-food for rats and 736 mg/kg-food for bobwhite quail. Cyhalofop-butyl is highly toxic to aquatic animals on an acute exposure basis. Toxicity data are available for several different test species. Available chronic toxicity data indicate effects to survival at concentrations >_287 μg a.i./L (NOEC = I 34) to fish and to reproduction at >_77.9 ,ug a.i./L (NOEC = 47.4) to invertebrates. In terrestrial plant studies, barnyard grass was the most sensitive species tested, with NOAEC and EC25 values of 0.007 and 0.017 Ib a.i./A, which are 2.4 and 5.9% of the maximum application rate for foliar sprays. Available test data for six species of dicots indicated no effects at the highest application rate. The Page 5 of 48

## freshwater diatom was the most sensitive aquatic plant species, with NOAEC and ECso values of

530 and 890 μg a.i./L, respectively. Based on the available evidence, the primary risk concerns for applications of this chemical are to non-target plants located in adjacent areas (receiving spray drift exposure). Conclusions of this ecological risk assessment for the cyhalofop rice use are summarized in Table 1. This table identifies taxa that are and are not at risk (evidence of risk and negligible risk, respectively) due to cyhalofop-butyl applications. This table also takes into account the certainty associated with the risk conclusions for a taxa. Appendix E includes general criteria for distinguishing between the different risk conclusions and certainty levels.

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## 2. Probleni Formulatioti

2.1. Mode of Action Cyhalofop-butyl is a member of the aryloxyphenoxy-propionate (APP) chemical class. These chemicals are selective inhibitors of de novo fatty acid biosynthesis. Specifically, they inhibit the first step in fatty acids biosynthesis, f.e., the carboxylation of acetyl-CoA to malonyl-CoA. This carboxylation process is catalyzed by the enzyme Acetyl-Coenzyme A Carboxylase (ACC'ase). There are two forms of ACC'ase: prokaryotic and eukaryotic, the latter of which is the form that is susceptible to cyhalofop-butyl. Since grasses only have the eukaryotic form, whereas broadleaf plants have both forms of ACC'ase, grasses are more susceptible to cyhalofop-butyl. Therefore, the target pests of this chemical are grasses (e.g., barnyard grass, crab grass, Johnson grass). Available toxicity data also suggest that the acid degradate of cyhalofop-butyl may also be herbicidal. 2.2. Use Characterization Cyhalofop-butyl is applied as a post-emergent herbicide for the selective control of grass weeds in the production of rice'. It has no pre-emergence or soil residual activity. Only actively growing grass weeds from the 1-2 leaf stage to 60 days before harvest are controlled at the time of herbicide application. Formulations include both liquid (emulsifiable concentrate, soluble concentrate, and ready to use solution) and granular forms. Cyhalofop-butyl can be applied either ground or aerial broadcast to wet and dry (drill) seeded rice fields. Cyhalofop-butyl is registered for use in eight states in two geographic regions of the United States: California and southern states. The seven southern states include: Arkansas, Florida, Louisiana, Mississippi, Missouri, Tennessee and Texas. For 2011, Figure 1 illustrates the use density (lbs/ mi 2 ) of cyhalofop-butyl applied among the two geographic regions in the U.S. The figure also includes the estimated amount of the herbicide used in both regions for rice production for the period 2001 to 2011 (USGS, 2011). California rice producers seed primarily by air directly into flooded fields. Except for parts of southwest Louisiana and the Texas Gulf Coast, most producers in the South drill seed (i.e. 

## planted in dry land prior to permanent flood). Planting typically begins in early March in Texas and southwest Louisiana. Rice farmers in the Mississippi Delta region plant the majority of the rice crop in April, whereas, farmers in California plant from late April through mid-May. Harvest begins in early or mid-July in Texas and southwest Louisiana. Peak harvest in the South is in September and early October, when the southern states harvests the most of their crop. Some producers in Texas and southwest Louisiana are able to re-flood their fields after harvest and achieve a partial second or "ratoon" crop from the initial crop's stubble. California typically begins harvest at the end of September and finishes by early November (USDA, 2012). ' Wild rice is not included in this assessment because on July 11, 2014, at the Office of Pesticide Program (OPP)facilitated Focus meeting, Dow Agrosciences verbally indicated that they intend remove wild rice from cyhalofopbutyl containing labels. Page 8 of 48

# Estimated Agricultural Use for Cyhalofop , 2011 EPest-High

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## Fio,nre 1: f:;timateci agricufttu•al use c?(cyhaioIC?p 131 thc tJnitec! Stat:es. iV`tap 1111.1strates the densitv (If)s.. , mi

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## ;ional loc'.-itions okvhi;re cyhalo(op-hiityl was usccl in the U.S. in 201 1. (;raph c9epicts estiinated uSe (in i»iili0n rOiIMds) on rice in the U.S. fior the heriod ?(.)(.) i throtigh 20 1 1( t..:S(;S, 2()1 1). 

## Page 9 of 48

## Currently, there are ten registered formulated products containing cyhalofop-butyl. Both Clincher

GR (62719-613) and Granule (62719-647) are registered in both California and southern states. One registration, Clincher GR (62719-613) has an alternate name Clincher DR in the southern states. Appendix A 

## contains two tables that itemize the registered products by region: California and southern states. Each table lists the registered products by formulation (liquid or granular), and then summarizes the rice seeding method, general application period, maximum single application rate, sequential application scenario and rate, total annual application rates, holding time and comments. Most formulated products containing cyhalofop-butyl allow a maximum single application of 0.288 pounds active ingredient per acre (Ibs a.i./A), with sequential applications at least 10 days later, for a total of 0.471b a.i./A per season; including ratoon crops. In California, two granular formulated registrations (Clincher GR and Clincher Granule) include Special Local Need supplemental labels that allow for a single maximum application rate of 0.36 lb a.i./A per year. Both supplemental labels are currently set to expire in August 2015. 2 Common among all cyhalofop-butyl labels are the following agronomic use restrictions: • Do not apply within 60 days of harvest; • Do not fish or commercially grow fish, shellfish, or crustaceans on treated acres during the year of treatment; • Do not rotate treated land to crops other than rice for 3 months following application; • Do not apply where runoff or irrigation water may flow directly onto agricultural land other than rice fields; • Do not apply if crop and weeds are under drought stress or reduced weed control may result; and, • Do not apply cyhalofop-butyl through any type of irrigation system. To help avoid injury to non-target terrestrial plants, all registered product labels have buffer zone application restrictions. Appendix B 

## contains two tables that summarize the buffer zone distances for each registered product label by region. Non-target peaches and nectarines have the greatest buffer distances in California of up to 4 miles when cyhalofop-butyl is aerially applied. Only RebelEx and Rebelsx CA contain buffer zone distance to protect endangered species. This is attributed to the co-formulated herbicides in each product, and not cyhalofop-butyl. Example language of the use of buffer zones on the product labels include: • The pesticide should only be applied when the potential is minimal for drift to adjacent sensitive areas that include: residential areas, bodies of water, known habitat for threatened or endangered species, and non-target crops. • Buffer zones are defirred as the distarrce between the application site and the sensitive agrricultural production crop. • Sensitive agricultural production crops include:■ 

## Commercial production of non-tar-aet 

## cereal and grass crops such as corn, sugar cane, sudangrass, sorghum, grass grown for seed, millet, and sod farms.

2 

### On July 11, 2014, at the Office of Pesticide Program (OPP) facilitated Focus meeting, Dow Agrosciences verbally indicated that they intend apply to extend both Supplemental labels beyond August, 2015. 

## Page 10 of 48■ 

## Commercial peaches and nectarines (for liquid formulations buffer restrictions are 2-4 mfles for aerial applications and 600 feet for ground applfcations). • If endangered plant species occur in the proximity of the application site, the following mitigation measure is required to avoid adverse effects. Leave untreated buffer zones of 85 feet from ground applications or 470 feet for aerial applicators. (Only on the RebelEx T " t 

## CA 3 and RebelEx T "' labels)
2.3. Label Uncertainties 

## This draft risk assessment is based on the current product registration labels. During development of this draft risk assessment, several issues and uncertainties were identified with the product labels. These issues have been communicated with the registrant, and the registrant has agreed to address the following identified label issues: l. There is ambiguity on some labels that allow users to apply both granule and liquid formulated cyhalofop-butyl containing products in a single season. In particular, it is unclear how the sequential application rate is determined for granulated formulated products; especially when the sequential application is liquid formulation. In some cases, the sequential product application rate is specified (e.g. 10 oz of Clincher CA), in other cases it is undefined. Therefore, the product user will be required to calculate not only the active ingredient rate, but also the product application rate. 2. Clincher GR • This label specifies the amount of the granular formulation for the initial application at 16 Ibs product/ acre. However, the label does not specify the maximum product application rate for the sequential application (e.g. 9.8 product oz. / acre). Here, the user must calculate the difference between the active ingredient maximum annual application rate of 0.47 lbs a.i./ acre and the initial application rate of 0.288 lbs a.i./acre; this difference is 0.182 lbs a.i./ acre from Clincher CA. Thus, the calculated maximum sequential product application rate would be 9.8 oz of Clincher CA. By rounding this to 10 oz, (not an improbable occurrence) the total annual application rate could reach 0.53 lbs a.i./ acre, or 11 % more active ingredient than currently registered. • Contains language indicating the product could be used on wild rice but wild rice is not a registered use. • Contains language recommending to use Clincher ® EZ on sequential applications where Clincher ® EZ is not registered for use in Southern States, but is only registered for use in California. • Contains language which includes Clincher ® DR; an alternate brand name for southern states (September 30, 2010). Clincher ® 5G • Contains language indicating the produet eould be used on wild rice but wild rice

3 

### Rebelex" CA is currently not being marketed in California; verbal communications from Dow Agrosciences 7/11/14. 

## Page 11 of 48

## is not a registered use. • For California, maximum seasonal application rates exceed 0.47 lbs ai/ A at 0.495 Ibs ai/ A. This is based on (page 9 of the Clincher O 5G label) the sequential Clincher o5G application rate of 3.83 lbs product / acre, in addition to the initial application rate of 5.33 lbs a.i./ A. • Contains language recommending to use Clincher ® EZ on sequential applications where Clincher ® EZ is not registered for use in southei

- n states, but is only registered for use in California. • For southern states, maximum seasonal application rates exceed 0.47 Ibs ai/ A at 0.495 Ibs ai/ A. This is based on (page 19 of the Clincher O 5G label) the sequential Clincher ® 5G application rate of 3.83 !bs product / acre, in addition to the initial application rate of 5.33 ibs a.i./ A. 4. GF-2764 • Minimum sequential application interval has a range of 7 to 14 days. A11 other registered product labels have a minimum sequential application interval of 10 days. 5. Clincher o Granule • Contains language recommending to use Clincher e EZ on sequential applications where Clincher ® EZ is not registered for use in southern states, but is only registered for use in California. 2.4. Previous Risk AssessmentsA number of ecological and drinkiilg water risk assessments have been completed for cyhalofopbutyl between the time of registration (2002) to present day. The general use patterns assessed have been similar to the currently labeled use patterns; however, the aquatic models used for risk assessment have evolved and the residues of concern have been refined over time. Nonetheless, identified risks have been siinilar with potential risks to aquatic and terrestrial plants and aquatic animals in rice paddies being the primary risk concerns. The primary differences between the current assessment and previous assessments incltide: (1) the current aquatic risk assessment is limited only to exposure from parent cyhalofopbutyl (previous assessments included some degradates of concern) and (2) the mammalian toxicity endpoint was changed.
2.5. Water Quality Cyhalofop-butyl is not identified as a cause of impairment for any water bodies under section 303(d) of the Clean Water Act (based on information provided at http://iaspub.epa.gov/tmdl watersl0/attains natlon cv.cause detail 303d?p cause group id=88 

## 5, accessed September 10, 2014). In addition, no Total Maximum Daily Loads (TMDLs) have been developed for cyhalofop-butyl (based on information provided at httn://iaspub.epa.gov/tmcil watersl0/attains nation.tmdl pollutant detail?p pollutant 91
- OLIn 

## id= 885K1) pollutant group name=l'ES"T'ICIDES 

## , accessed September 10, 2014) and there are no
Page 12 of 48

## aquatic life criteria for cyhalofop-butyl (based on information provided at

httn://www.epa.gov/waterscience/criteria/aglife/index.hti

- ni)



## . 2.6. Stressors of Concern Available toxicity data (Table 2) indicate that the degradates of cyhalofop-butyl are less toxic than the parent to aquatic organisms. In cases where toxicity was observed in organisms exposed to the parent (i.e., bluegill sunfish LC50 = 760 μg a.i./L), no mortality was observed in the same test species exposed to concentrations of degradates that were two orders of magnitude greater than the LCso of the parent. In studies conducted with terrestrial plants, only the acid degradate showed toxicity, with EC25 values for decreased shoot weight in vegetative vigor studies that were similar to those of the parent for corn and barnyard grass. This suggests that the acid degradate has herbicidal active. For this assessment, only cyhalofop-butyl is of toxicological concern for aquatic organisms. For terrestrial plants, cyhalofop-butyl and cyhalofop-acid are of concern. For modeling purposes, the parent only will be considered in water. For terrestrial animals, estimated exposures are related to the application rate. For terrestrial plants, since both exposure and effects are linked to the application rate and since cyhalofop-acid is of similar toxicity, RQs will be derived using application rates of the parent. If cyhalofop-acid is formed in the terrestrial plant toxicity studies conducted with the parent, it is indirectly accounted for in the assessment.

Page 13 of 48

### Table 2: '1'oxicity clat.t avail:able for cyhalofop-butvl and dcgradates

Test Endpoint Cyhalofop Cyhalofop ('} halofop Cyhalofop s ecies units

- 

### butvl

- 

### acid

- 

### amide

- 

### diacid FHPBA HPP;e MRIDs Rainbow LCso 45000217, 

### trout (μg a.i./L) >490 >100,000 1

~ 

### A >95,400 ti: ~ ~ 

### 1;1 45000213, 

### 45000212 Bluegill LCso 45000216, 

### sunfsh (μg a.i./L) 760 >99,200 88,400 >98,700 '\':1 NA 45000215, 45000214 45000226, 45000221, ECso (Etg a.i./L) >2700 > 100,000 = 100,000 >95900 >400 >400 45000222, 45000220, 

### Daphnia 45000224, 

### magna 45000225

21 d 45000230, 

### NOAEC 47.4 NA NA 98 300 NA NA 45000232 

### (jig a.i./L) 45000432, 45000435, Green ECso >1000 >78200 50000 >96400 >400 >400 45000436, 

### algae (μg a.i./L) 45000434, 45000437, 45000438 

### EC2s Barnyard ( 

### g a ' t ' /ha ' 45000430, grass shoot 19 >580 >580 >350 >350 45000431



### weight in VV stud ) Corn ECZS 

### 9

~ 

### ?.8 = ~ 

### 580 =>580 -3 5 

### 0 > ;50 45000430,



### a.i./ha) 45000431 NA = not available


## 2.7. Analysis plan 2.7.1. Ecosystems of Concern Given that cyhalofop-butyl applications are only allowed for rice, ecosystems of concern are those that are in proximity to rice paddies. Terrestrial habitats adjacent to the paddies may receive spray drift deposition from applications of liquid based formulations of cyhalofop-butyl. Non-target aquatic organisms (e.g., fish, aquatic invertebrates, plants) inhabiting rice paddies may also be exposed for direct applications. Aquatic ecosystems that occur down stream of rice paddies are also of concern, potentially being exposed to cyhalofop-butyl when water is released from the rice 

## paddy into those down-stream habitats. Because the spatial extent of eyhalofop-butyl registrations is limited, i.e., 

## Arkansas, California, Florida, Louisiana, Mississippi, Missouri, Tennessee and Texas, ecosystems of concern exist within those states.

Page 14 of 48

## 2.7.2. Risk Hypotheses

For cyhalofop-butyl, the following ecological risk hypotheses are being employed for this risk assessment: Terrestria! Environment Exposure to cyhalofop-butyl residues on seeds, insects, and foliage due to direct spray drift from labeled use of the pesticide will cause reduced survival, growth and reproduction to terrestrial vertebrates (birds, mammals, reptiles, terrestrial-phase amphibians) and terrestrial invertebrates. Exposure to cyhalofop-butyl residues on foliage due to spray drift resulting from labeled use of the pesticide will result in reduced survival and biomass to upland plants and riparian/wetland plants in areas adjacent to a treated rice paddy. Aquatic Environment • Exposure to cyhalofop-butyl residues in paddy water due to direct applications according to labeled uses of cyhalofop-butyl will cause reduced survival, growth and reproduction to aquatic animals and non-target plants located within the rice paddy. • Exposure to cyhalofop-butyl residues in water released from treated rice paddies will cause reduced survival, growth and reproduction to aquatic animals and non-target plants located within the aquatic habitats downstream of the treated rice paddy. 2.7.3. Conceptual Diagram Figure 

## 2 depicts the conceptual model of the fate and potential effects associated with applications of cyhalofop-butyl to rice. In the figure, dashed lines represent pathways of exposure that are unlikely to occur because of physical or chemical properties of the chemical. Forexample, cyhalofop-butyl is not expected to volatilize or significantly bioaccumulate. Major nontarget organism exposure routes of concern for this assessment include ingestion of food items that have received direct deposition (i.e., on the treated field) or spray drift to non-target areas, contact with treated water within the paddy or ecosystems receiving released water.

Page 15 of 48Cyhalofop-butyl applied to rice paddy Stressor



### v--- ~ ~ --- 

# ,-----1 ~ ~----'-

_ '

__ Source/ ; Volatilization , Direct Spray Runoff/ Release of ; Lea hing ; Transport; of degradatesi ; Deposition Drift Erosion paddy water ;(Inflltration/ ;

, Wind ~ ' Percolation ' Pathwa s, -~~~----' ~ y Sus ension• ; _ ~ ~ ~ -----r------ ~--p ------ ' ' --~----n Source/ TerrestrialFood Upland ^ Riparian/ Receiving ;Groun~Jwater~ ----- Exposure Residues (foliage, Foliage/Soil Wetland Water Body/

_ _ _ _ _ _ _ _ Media fruit, insects Foliaqe/Soil Sediment

Attribute Individual Animals Changes Reduced survival Reduced growth Reduced Direct contacU Direct contact/ Uptake/

Root Uptake Root Uptake Adsorption
Terrestrial Wetland/ Aquatic 

### Upland Riparian Plants Plants, Inverts Plants

IS 21a.LlI Seedling emergence p.o.RulaliQn Vegetative vigor Reduced population growth Gill/

_ _ Ingestion

Integument ~ 

### — ♦ up the Uptake Food Chain Aquatic Piscivourous Invertebrates Vertebrates Aquatic Birds, Vertebrates Mammals
lLlljlvttdudl 1L1iGll1dLl81 vertebrates and Apit]aIS invertebrates Reduced Reduced survival survival Reduced Reduced growth growth Reduced Reduced reproduction Exposure Ingestion Route
Terrestrial I nvertebrates Receptors Birds, Mammals,

Reptiles, Terrestrial Phase Amphibians



### F i-urc 2: 9:coItst, 'ica9 C'nttcrptu:tl N'I.xlei f'or eyhitlrtfot.a-hutyl a pplic:ttitrns to rice itacldie , ,. 

## Assessment endpoints are intended to relate to ecosystems at risk. If risks are expected for a given species/taxa based on the risk assessment, then risks might be expected to translate to higher levels of biological organization (e.g., ecosystems). Assessment endpoints are represented by measurement endpoints, which are the most sensitive toxicity endpoints from a surrogate test species, used to estimate treatment-related direct effects following acute and chronic exposure. Measurement endpoints are standardized so that acute toxicity is represented by levels that result in mortality to 50% of tested individuals (i.e., LCso, LDSo and ECso) and chronic toxicity is represented as a no observed adverse effect concentration or dose (i.e., NOAEC or NOAEL). Table 3 includes the most sensitive toxicity endpoints available for cyhalofop-butyl that will be used as measurement endpoints to assess risks to terrestrial and aquatic organisms. These values are used to derive risk quotients.



## Page 16 of 48

### 'Table 3: iNIcasurcnient endpoints to derive ltisit Ouotients (ItQs) t'or cvlialofon-butvl. Taxa Species Toxicity Value* Citation Study Re resented MRID ClassiCcation 

### Birds, terrestrial- LDso > 2250 mg/kg-bw 45000207 Acceptable phase Anas platyrhynchos LCso > 5620 mg/kg 45000209 Acce table amphibians and (Mallard Duck) NOAEC = 736 mg/kg 45152501 Acceptable re tiles Rattus norvegfcus LDso>5000mg/kg 45000240 Acceptable NOAEC = 100 mg/kg 45000419 Acceptable 

### Mammals laborato ( rY rat ) 

### Apfs mellifera 48 h NOEL = 100 μg 45000502 Acceptable "I'crrestrial (hone bee) a.i./bee Invertebrates Eiseniafoetida 14 d NOAEC = 1120 45000504 Supplemental

earthworm) m Terrestrial and 

## Echinochloa crus- NOAEC = 0.007 Ib a.i./A wetland plants ga!!i (Barnyard r

~ s 

### EC25 = 0.017 Ib a.i./A 45000431 Acceptable Lepomis Fish and aquatic- macrochrrus 96 h LCso = 760 45000219 Acceptable phasc Blue ill

pimephales aniphibians promelas (Fathead 31 d NOAEC = 134 45000231 Acceptable

minnow Crassostrea virginica (Eastern 96 h ECso = 520 45014704 Acceptable Aquatic o ster

Daphnfa magna 21 d NOAEC = 47.4 45000230 Supplemental invertebrates Chfronomus 28 d NOAEC = 661 (pore 45000508 Supplemental

ri arius (mid e) water Aquatic Plants Navicula 5 d NOAEC = 530 (unicellular and pelliculosa 5 d ECso = 890 45000429 Acceptable vascular) (freshwater diatom 

## 2.7.4. Modeling Approach Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of cyhalofop-butyl using maximum

- labeled application rates and methods. For this assessment, pesticide residues on the food items of terrestrial animals (birds, mammals, amphibians and reptiles) are assessed using the T-REX model (v. 1.5.2). The AgDRIFT model (version 2.01) is used to estimate the deposition of cyhalofop-butyl in areas that are adjacent to the treated field. In this assessment, it is assumed that granules do not drifft, therefore, AgDRIFT is only used to simulate deposition of liquid formulations. The modified Tier I Rice Model is used to estimateconcentrations of cyhalofop-butyl in the flooded rice paddy over time. More information on the TREX and AgDRIFT models is available at: http://v. , %v4v.epa.

~ 

## ov/pesticides/science/models db.htm



## . Appendix B contains an explanation of the modified Tier I rice model.

Page 17 of 48

## 3. Exposure Analysis

3.1. Environmental Fate and Transport Summary Table 4 summarizes the physicochemical properties of cyhalofop-butyl. A more comprehensive and detailed physicochemical properties and environmental fate characteristics of cyhalofop-butyl and its degradates have been well documented in previous risk assessments (USEPA, 2008: DP Barcode 357419), and are briefly summarized herein. Cyhalofop-butyl is slightly mobile, 2892 — 7960 1/kg, and slightly soluble at 0.44 mg/L. With a calculated Henry's law constant of 9.4 x 10 -9 atm-m 3 /mole, the herbicide is not likely to volatilize substantially at environmental temperatures. It has a log Kow of 3.3, indicating that it has a higher affinity for organics than for water and has the potential to accumulate in organisms. However, a fish bioconcentration study indicates that cyhalofop-butyl does not significantly bioconcentrate. Cyhalofop-butyl degrades to cyhalofop-acid by biologically-mediated hydrolysis in less than a day. Further degradation leads to cyhalofop-amide and to cyhalofop-diacid. Hydrolysis and photolysis are much slower compared to biological degradation at neutral to acidic pH. Abiotie hydrolysis is more rapid at pH 9. Appendix D provides a table that summarizes the major and minor degradates of cyhalofop-butyl, their structures, and the range of maximum percent of applied equivalents in degradation studies. These properties indicate that cyhalofop-butyl's degradates will have little tendency to volatilize or to sorb to soil. The degradates will be mobile due to the low K o , values. Cyhalofop-butyl residues will likely degrade in the water column rapidly and predominantly mineralize to carbon dioxide. Residues in paddy water from California and Arkansas field studies dissipated to below detectable levels after 28 days. Tahle 4: 1'hvsicochentic..;l 0'rooc.rtics cff 

### t.:t'It<jlo9'nu-htitN

- l.

Parameter Value Description Source (M R[ D) Selected Physical/Chemical Parameters Molecular Formula C2o HZo 

### FNO a - 

### 45000201 Molecular Mass 

## 357.4 g/mol 45000201 Vapor pressure 

## (25°C) <1.0 x 10'' torr -- 43193203 Aqueous solubility 0.44

- 

### 45000203 

## (20°C) mg/L Henry's Law Constant 

## 9.4 x 10' 9 (20°C) (calculated) Not likely to volatilize 45000203 atm-tn'/mole Log octanol-to-water partition 

## 3.3 -- 45000203 coefficient (Kow) 

## (25°C) Acid dissociation constant (pKa) Not Measurable -- 43000203 

## (23±1°C)


## Page 18 of 48

### Pa ra meter Value Description Sou rce (MRID) Persistence Hydrolysis: Half-life (25f 1°C) 0.5 to Stable --- 45000510 days 45000511 Aqueous Photolysis: Half-life 41.5 (alpha)' ) 45014712 (25±1'C) days 36.7 (beta) Supplemental Soil Photolysis: Half life Not a major degradation (25f 1°C) pH 5.8: Stable pathway 45000514 days 9 Silt Loam (AR) 45000515 8 Clay Loam (CA) 2.32 Silt Loam (AR) 45000516 Aerobic Soil Metabolism: DTso (25f 1

- C) 28 Sandy loams (Italy) 28 Clay loam (ltaly) days 45014?IS 29 Loamy Sand (Germany) 44 Sandy clay loam (UK) 0.1 Flooded 45000518

Silt Loam Sediment (AR) Flooded Aerobic Aquatic Metabolism: DTso 0.18 Silt Loam Sediment days (Spain) 45000526 Flooded 0.22 Silt Loam Sediment (France) Anaerobic Aquatic Metabolism: DStI 0.5 Silt loa n 

# (A R l /) ond water 45000517 0 

### C) days Mobility Soil-water partition coefficients (Kd) 17.8

— 

### 75.0 1/kg Sl ghtly Mobile 45000519 Organic carbon-normalized 2892

- 

### 7960 1/kg coefficients (Koc) Field Dissipation Aquatic Field Dissipation: Silt loam soil (AR) flooded DTso 0.04 Residues measured in 45000520 days water



## Page 19 of 48

### Parameter Value Description Source (MRID) 

### Clay loam soil (CA) flooded 0.01 45000520

Residues measured in water Fish Bioconcentration 

### Fish Bioaccumulation Factors Edible: 27 Does not signifcantly 45000233 Whole Body: 507-672 bioconcentrate Abbreviations: °C - degrees Celsius; d= day; DT - disappearance tinie; hrs. = hours; in. = inch; 1= liters; kg = kilograms; I.OQ = level of quantitation; <= less than 1) alpha and beta represent radiolabeled ring.


## 3.2. Estimated exposure 3.2.1. Direct Deposition onto terrestrial Food Items (located on treated paddies) Cyhalofop-butyl concentrations on terrestrial animal food items were estimated using the T-REX model (Table 5). These EECs are based on direct applications of the chemical to the paddy. The rnodel was parameterized with two applications (at rates of 0.29 and 0.18 ib a.i./A) spaced 10 days apart. These values diffei• from the aquatic assessment because they correspond to liquid formulation applications whereas the maximttm rate simulated in the aquatic exposure assessmentapplied to granular formulations. The default half-life of 35 days was used because no chemicalspecific data were available to refine the default assumption. Given the available half-life data from laboratory fate studies, this half-life is likely an overestimation. TabEe 5: E stinaated c-«neentrations on different fooc.i itt•m, Iocatecl in tre<ttetl ric:c 

## natldies. Food item 

### Concentration

( 

### nig a.i./k Short Grass 100 Tall Grass 46 Broadleaf plants 56 Fruits/ ods/seeds 6.3 Arthro ods 39 

## 3.2.2. Estimated concentrations in water The Tier 1 Rice Model was used to estimate environmental concentration (EECs) in the rice paddy under flooded conditions. The post permanent flood scenario was modeled because dryland applications of cyhalofop-butyl must begin flooding within three hours of application. Table 6 sutnmarizes the model input parameters selected pursuant to the model input guidance document (USEPA, 2007). Page 20 of 48

## Table 6: 7`ier I 

## Rice Model Anplfcation 

## ScenQrios ancl Innut Pararneters Southern California Califo •nia California States & 

### (Special Local Need (Special Local leed

Soutl ee•n States Supplemental) Suppleniental) Clincher ® DR Clincher' 5G; $ 

### Registered + 

### Clincher ® GR; or ® 

### Clincher GR x Clinchcr Granulc 

### Product(s) Clincher ® DR Clincher ® Granule Seeding Type Wet Application Per od Post I'ermanernt Floo(i 

### Application Sequential' Single Events Maximum Applioation Single:0.288 Single:0.288 Single:0.36 Single:0.36 Rates; ) followed by 0.207 followed by 0.186 11 Annual: Annual: (Ibs a.i. /A) Annual: 0.495 Annual: 0.474 0.36 0.36 Water Depth 10.0 (cm) Soil-Water Distribution 0.463 Coefficient, Kd (Ukg) Aerobic Aquatic 0.2 Metabolism ttn (da s) Aerobic Aquatic Metabolism 0.0165 rate constant, k da '' Abbreviations: A= acre; a.i. = active ingredient; kg = kilogram; Ibs = pounds; ha = hectare 1 Sequential refers to the splitting of product applications into two events separated by at least 10 days. 2 The second application is a liquid formulation such as Clincher ® CA and Clincher® SF. 3 Application rates were rounded to 3 significant digits, except for the existing label for Clincher ® GR and Clincher® Granule single event applications. 

## Assumptions. Data Gaps and Uncertainties Assumptions, uncertainties and limitations of the modified Tier I Rice model were fully explored in the model's guidance document (USEPA, 2007). To account for known and unknown data gaps and model uncertainties, several conservative assumptions were incorporated into the model analysis and includes the following:

Page 21 of 48

## 1. To account for the discrepancy identified on the Clincher o DR product label's total annual application limit for sequential applications, a total annual application rate of 0.495 ibs a.i. /A was used instead of 0.47 Ibs a.i./A; 2. The highest total annual single application rate of 0.36 lbs a.i./A was used for the California Special Local Need supplemental product labels; 3. A 10-cm (4-inch) flood was assumed to be representative of the average depth of the rice paddy. Rice paddies have a slight slope for drainage purposes. The label recommends flood depths of 2-5 inches. Exposure estimates are more or less conservative when paddy water depths are shallower or deeper, respectively, than 10 cm; and, 4. The modified Tier I Rice model does not account for all the routes of dissipation for the pesticide, such as all types of pesticide degradation, mass transfer, volatilization, or other dissipation pi

- ocesses. "ratale 7: `('ies i 12ire Mocicl Igcstilts: l;stimated I:nvironrncntal Cortcentralic ns ( EI:C;) by 3 3 

## rc,duct ApplicatEon Sci'oltrio. California California California (Special Local (Special Local Southern & 

### Need Need States Southern States Su lemental ) Su lemental Clinchcr" DR Clincher® 5G; Registered + 

### Clincher® GR; or Clinchery GR Clincher' Ciranule Product(s) 

### Clincher" DR Clincher ® Granule Peak 

### 290.6 290.6 363 363 (ug/L) 21-day A4ean 

### 24.6 23.5 17.8 17.8 (ug/L) 60-day \4ean 

### 8.6 8.2 6.2 6.2 (ug/L) 

## Results Table 7 summarizes the Tier I Rice Model results. Both Clincher GR and Granule have Special Local Need suppletnental registration labels, and are applicable only to the state of California. Both labels provide single naximum application rates of 0.36 lbs a.i./ acre per event and annually. Although the total annual application rate is lower than other cyhalofop-butyl containing labels of 0.47 Ibs a.i./ acre, the single higher application rate produces the peak highest ecological estimated environmental concentration (EEC) of 363 ppb. Figure 3 depicts the concentrations of cyhalofop-butyl in paddy water for up to 14 days following application; the required minimum retention period of flooded rice paddies treated with granular formulations. Because of the very short half-life of cyhalofop-butyl in water (e.g. DT5o = 2.4 to 5.3 hours), the residues decrease by orders of magnitude below the initial peak concentration the day aftec - application. As shown in the figure, when multiple applications yield two peaks, one on the first day, and the second 10 days later when the second application occurs.

Page 22 of 48

# 400

mliil 

# — 300 an

~ 

# 250

_ 0 

### L 200

~ 

### c a~ 

### ~ 

# 150 0

: 

# a 100 0

a~ 

# a 50 Q 7 Rice Paddy EECs vs Time 3 Maximum Sequential r

................... ..... . .. ...... . ..... . . 

## i Application Rates ;

# ♦ Maximum Single
~ 

### Application Rate !

, ~ 

### .,w.. ....,,., ~ 

### ,,,. _.. .................. ~ 

### .,, ~ 

### .,, ~ 

### ,,,..T-

~ 

### . ~



### ..... ~ 

### ..._

# ■ - -- -------_..



# 0 5 10 15 Days After Application Figure 3: Estimatec! eiaiiy cc

~ 

## nce

~ 

## itrations of ryhhlofop-l

~ 

## utyl nfter apl

~ 

## lic:atiura o.felthet• Clinclier (;K or t;r

~~ 

## ni

~ 

## lc sulyl

~ 

## lemcntai labels at the sinl;lc applic

~ 

## ation r.ate of 4.36 Ebs aa.i./ A. 3.2.3. Spray Drift Transport The spray deposition curves for aerial and ground applications as calculated by AgDRIFT are provided in Figures 4 and 5, respectively. Note that these figut•es represent point estimates of spray drift deposition at distances from the edge of the field. Values are expressed as the percent of the applied rate. These curves are used to determine the distance from the edge of the field where risk extends to non-target plants.

Page 23 of 48

### 50.0% 45.0% 40.0% 35.0% -0 30.0% a ~ 

### Q25.0% 

### cm 0 20.0% a 15.0% 10.0% 5.0% 0.0% ..nr.. 4nn !n ffne .ia..Js.s 

### > ilets



## 0 200 400 600 800 1000 Distance from edge of field (feet) Figure 4. Percent of applied pesticide at different distances from the edge of the field treated by aerial methods (calculated using AgDRIFT

v2.01; 10 foot release height).


## 50% 45% 40% 35%

- 

### o 30% a-25% ca

~ 

### ° 20% 0 

### 15% 10% 5% 0% 0 Hinh hnnm ACAG vPrv finP tn fino



### 100 200 300 400 500

Distance from edge of field (feet) Figure S. Percent of applied pesticide at different distances from the edge of the field treated by ground methods (calculated using AgDRIFT v2.01).



## Page 24 of 48

## 4. Effects Analvsis

4.1.Toxicity data 

## Available toxicity data indicate that cyhalofop-butyl is practically non-toxic to mammals, birds and bees on an acute oral exposure basis. It is also practically non-toxic to birds on a sub-acute dietary basis and bees on an acute contact basis. In sub-chronic exposures involving earthworms, no effects were observed at 1120 mg/kg-soil. Available chronic toxicity data with mammals and birds indicate no effects to reproduction or offspring at 100 mg/kg-food for rats and 736 mg/kg-food for bobwhite quail (Table 8). 

## Cyhalofop-butyl is highly toxic to aquatic animals on an acute exposure basis. Toxicity data are available for several different test species. Available chronic toxicity data indicate effects to survival at concentrations >_287 ,ug a.i./L (NOEC = 134) to fish and to reproduction at >_77.9 ,ug 

## a.i./L (NOEC = 47.4) to invertebrates. (Table 9). 

## Based on a seedling emergence and a vegetative vigor study for non-target terrestrial plants (Table 10), 

## barnyard grass (a monocot) was the most sensitive species tested. The lowest parent cyhalofopbutyl EC25 for barnyard grass is a vegetative vigor endpoint of 0.0017 lb a.i./A (corresponding NOAEC = 0.007). Available test data for six species of dicots indicated no effects at the highest application rate. The freshwater diatom was the most sensitive aquatic plant species, with NOAEC and EC50 values of 530 and 890 μg a.i./L, respectively.

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## 4.2.Reported Ecological Incidents



## Four incident reports are included in EIIS. Two involved incidents associated with direct effects to treated rice. Two involved incidents with non-target plants exposed through spray drift. The incident reports are summarized here. Incident number I014266-003: 

## An aerial application of Clincher was made to rice field near a milo sorghum field in June, 2003 

## in MO. The milo field suffered plant damage from spray drift. The legality of the use was classified as a"misuse". The certainty was identified as "probable". Incident number I015360-003: 

## In May, 2004 

## in CA, aerial application was made to a rice field. The spray drift resulted in damage to 120 

## peach trees less than 2 

## miles from the site of application. There was red spotting on the leaves and some defoliation of the leaves. Lab analysis confirmed the presence of Clincher on the peach leaves. Since this incident occurred inside the 2 mile buffer zone, it is considered an accidental misuse. The certainty was identified as "probable." Incident number I014266-003: 

## An application of Clincher was made to rice field in June, 2003 

## in WI. Damage to the treated rice was observed. The incident was associated with a registered use. The certainty category was identified as "possible". Incident number I013636-007: 

## An application of Clincher was made to rice field in January, 2003 

## in CA. Decrease in yield of rice was reported. The incident was associated with a registered use. The certainty category was identified as "possible". 4.3.Endocrine Disruptor Screening Program 

## As required by FIFR.A 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, neurotoxicity, 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 maturation, 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 required by FFDCA section 408(p), 

## cyhaolfop-butyl 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 effect in humans or wildlife similar to an effect produced by a"naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." The EDSP employs a two-tiered approach to making the statutorily required determinations. Tier I 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
Page 29 of 48

## systems. Chemicals that go through Tier 1 screening and are found to have the potential to

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any adverse endocrine-related effects caused by the substance, and establish a dose-response relationship between the dose and the E, A, or T effect. Under FFDCA section 408(p), the Agency must screen all pesticide chemicais. Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013 4 and includes some pesticides 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. Cyhaolfop-butyl is not on the first or second list. The second list represents the next set of chemicals for which EPA intends to 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. 5
5. Risk Estimation and Characterization 

## For this preliminary assessment of cyhalofop-butyl, the deterministic RQ method was used to provide a metric of potential risks. The RQ is a comparison of exposure estimates to toxicity endpoints (i.e., RQ = EEC/toxicity endpoint). The resulting RQs are compared to the Agency's risk levels of concern (LOC), which are the Agency's interpretive policy such that when acute or chronic risk LOCs are exceeded, the need for regulatory action may be considered. These criteria are used to indicate when the use of a pesticide, as directed on the label, has the potential to cause adverse effects to non-target organisms. For acute and chronic risks to animals, the LOCs are 0.5 and 1.0, respectively, and for plants, the LOC is 1.0. For each taxa, RQs are generated and risks are discussed. This discussion includes consideration of additional data and lines of evidence.

5.1. Terresta-ialOrganisnis 5.1.1. Anianals 

## Acute RQs generated using the T-REX model do not exceed acute LOCs for terrestrial animals, including birds (and terrestrial-phase amphibians and reptiles) and mammals (Tables 11 and 12). This applies to both non-listed and listed species (LOCs = 0.5 and 0.1, respectively). Chronic RQs do not exceed the LOC for birds, indicating that reproductive effects are not expected for non-listed and listed species (LOC = 1 for both). Chronic RQs for mammals consuming grass ^ See http://www.reaulations.gov/#!docinnentDetail;D=EPA-HO-OPPT-2009-0477-0074 

### for the final second list of chemicals. 5 

### http://www.epa.gov/endo/


## Page 30 of 48

## and broadleaf plants located on the treated field exceed the LOC (1.0), indicating potential risk to

offspring of mammals. There is uncertainty associated with the conclusion that exposures to cyhalofop-butyl will impact mammals because, 1) cyhalofop-butyl is not particularly persistent in the environment b , therefore, mammals feeding on the treated field may not consume cyhalofop-butyl residues for a sufficient amount of time to represent a chronic exposure; 2) the magnitude of the effect to mammals was only 5-7% decrease in body weight of the F 1 generation; although this was a statistically significant effect; the biological relevance of this effect is uncertain and 3) there is uncertainty associated with the NOAEC due to a 10-fold dose spacing between test concentrations.
i abEe 1 1: I3tiv for liirds (and terrestrial-phase antphdbians and reptiles) 1'ee<linl; c rt thc trcateci iicfc6.
Dietary I:tem Acute, dose-based RQs * Acute, dietary Based RQs * Chronic,

dietary Based RQs* * 20 g bird 100 g bird 1000 g bird AII sizes All sizes Short Grass <0.10 <0.04 <0.01 <0.02 0.14 Tall Grass <0.04 <0.02 <0.01 <0.01 0.06 Broadleaf plants <0.05 <0.02 <0.01 <0.01 0.08 Fruits/ ods <0.01 <0.01 <0.01 <O.OI 0.01 Arthro ods <0.04 <0.02 <0.01 <0.01 0.05 Seeds <0.01 <0.01 <0.01 <0.01 O.OI *Non-listed species LOC = 0.5, Listed species LOC = 0.1. **Non-listed and listed species LOCs = 1.0.
l:ibie 12: F2Os lot - mamnlals feedin<r on the treated fielti. 13o1<i values exceed I.10C.

` 

### Dietary Item Acute, dose-based RQsK Chronic, dose-based RQs** 15 g mammal 100 g mammal 1000 g mammal 15 g mammal 100 g

mammal 1000 g

mammal Short Grass <0.01 <0.01 <0.01 8,7 7.4 4.0 Tall Grass <0.01 <0.01 <0.01 4.0 3.4 1.8 Broadleaf plants <0.01 <0.01 <0.01 4.9 4.2 2.2 Fruits/ ods <0.01 <0.01 <0.01 0.54 0.46 0.25 Arthro ods <0.01 <0.01 <0.01 3.4 2.9 1.6 Seeds <0.01 <0.01 <0.01 0.12 0.10 0.06 *Non-listed species LOC = 0.5, Listed species LOC = 0.1. **Non-listed and listed species LOCs = 1.0.

6 

### Although soil metabolism half-lives range 2.3-44 days, after cyhalofop-butyl is applied to the rice paddy as a foliar spray, the paddy is flooded. Once the paddy is flooded, cyhalofop-butyl is expected to go through several half-lives within a day (aerobic aquatic half-life: 0.1-0.22 days). 

## Page 31 of 48

## Available honey bee data include acute NOAEL values of 100 μg 

## a.i./bee for both contact and

oral exposures routes (Table 9). According to EFED's risk assessment method for honey bees, the contact value can be converted to Ib a.i./A by dividing by 2.7 (μg a.i./bee per 1 lb a.i./A). The result is an NOAEL of 37 lb a.i./A. Similarly, the oral NOAEL can be converted by dividing by 32 (μg 

## a.i./bee per l Ib a.i./A), with a NOAEL value of 3.1 lb a.i./A. Since both values are at least an order of magnitude below the maximum allowed application rate for cyhalofop-butyl, acute effects to adult bees are not expected. It should be noted that there is uncertainty associated with the risks of cyhalofop-butyl to bees due to a lack of chronic toxicity data for adults as well as acute and chronic toxicity data to larvae. No data are available to assess the chronic toxicity of cyhalofop-butyl to adult honey bees. Data are not available to assess the acute or chronic toxicity of cyhalofop-butyl to honey bee larvae. Despite this lack of data, the risk of cyhalofop-butyl to bees is considered negligible because exposure is expected to be minimal. This is because 1) rice is not a pollinator attractive crop and 2) cyhalofop-butyl degrades rapidly in the environment.
5.1.2. Plants Spray drift from aerial and ground spray applications of cyhalofop-butyl are expected to pose a risk of growth effects to non-target grass species. Given that no effects were observed in dicots exposed to cyhalofop-butyl at rates exceeding the maximum application rates allowed on labels, effects to dicot species are not expected. The most sensitive endpoints for terrestrial plants correspond to effects to shoot weight of barnyard grass from a vegetative vigor study. These endpoints, i.e., 

## NOAEC = 0.007 lb a.i./A and EC25 = 0.0017 lb a.i./A equate to 2.4% and 5.9% of the maximum single application rate (0.291b a.i./A) allowed for liquid formulations containing cyhalofop-butyl. When considering the spray drift deposition predicted by AgDRIFT (Figures 4 and 5), cyhalofop-butyl exposures may cause effects to grasses that are located well beyond the edge of the treated field. Table 13 presents the farthest distances from the edge of the treated field where spray drift deposition is of concern based on NOAEC and EC25 values for barnyard grass. For aerial applications, risks extend beyond the predictive abilities of the Tier I AgDRIFT model (i.e., >997 

## feet). For aerial applications, risks extend as far as 100 feet from the edge of the field. If nozzles are used that limit the droplet spectra to medium or coarse, the distances from the edge of the field where risk extends are lowered. T'able 13: .approximate distance froiu ed r e nf field to i

- each NOA)

~ 

## ;C aud I?C25

~~ 

## alues for barnyard g r.i; s. 

## Application description (method, droplet spectra, release height) Distance from edge of field (ft) to 

# NOAEC llistancc from edge

of field (ft) to F;C25 Aerial, very fine to fine >997 600 Aerial, fine to medium 1400 175 Aerial, medium to coarse 1200 100 Ground, ver fine to fine, hi h boom 100 50 Ground, fine to medium/eoarse, hi h boom d 25 10
Page 32 of 48

# ~

roun ver fine to fine, low boom 25 40 fine to medium/coarse, low boom 15 5 5.2. Aquatic OrganismsAcute and chronic RQs were derived using the maximum estimated concentrations of cyhalofopbutyl in rice paddies along with the most conservative endpoints for fish, invertebrates and aquatic plants (Table 14). The acute RQ for fish exceeds the listed species LOC. The acute RQ for invertebrates exceeds the non-listed as well as the listed species LOC. These LOC exceedances indicate potential risk of cyhalofop-butyl to fish and invertebrates inhabiting a rice paddy on the day that it is treated with cyhalofop-butyl. Because of the rapid degradation of cyhalofop-butyl, estimated exposures on the day after the exposure (11.4 μg a.i./L; Figure 3) are insufficient to cause a risk concern especially if paddy water is held before release into downstream habitats. Therefore, effects to non-target organisms outside of the rice paddy are not expected. RQs for plants and chronic RQs for animals are below the LOC (1.0), indicating low risk of effects to plants or chronic effects to animals. '1`ablc 14: 12(}s f'or Atitiatic ()manisms. Parameter Fish Invertebrates Plants Acute EEC a.i./L) 363 363 363 Acute End oint a.i./L 760 520 530 Acute RQ 0.48* 0.70** 0.68 

## Chronic EEC a.i./L 6.2 17.8 Not applicable Chronic End oint a.i./L) 134 47.4

_ Chronic RQ 0.04 0.38 

## *Exceeds listed species LOC of 0.05. **Exceeds non-listed species LOC of 0.5 and listed species LOC.
5.3. Listed Species In November 2013, 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 summary of their joint Interim Approaches for assessing risks to listed species from pesticides. The Interim Approaches were developed jointly by the agencies in response to the National Academy of Sciences' (NAS) recommendations and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences between the EPA and the Services. The NAS report outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that EPA and the Services must conduct in connection with their obligations under the Endangered Species Act (ESA) and FIFRA. The joint Interim Approaches were released prior to a stakeholder workshop held on November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and Evaluation Group (SFIREG) meetings, and held a stakeholder workshop in Apri12014, allowing Page 33 of 48

## additional opportunities for stakeholders to comment on the Interim Approaches. As part of a

phased, iterative process for developing the Interim Approaches, the agencies will also consider public comments on the Interim Approaches in connection with the development of upcoming Registration Review decisions. The details of the joint Interim Approaches are contained in the white paper "Interim Approaches for National-Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report," dated November l, 2013. Given that the agencies are continuing to develop and work toward implementation of the Interim Approaches to assess the potential risks of pesticides to listed species and their designated critical habitat, this preliminary risk assessment for cyhalofop-butyl does not contain a complete ESA analysis that includes effects determinations for specific listed species or designated critical habitat. Although EPA has not yet completed effects determinations for specific species or habitats, for this preliminary assessment EPA conducted a screening-level assessment for all taxa of non-target wildlife and plants that assumes for the sake of the assessment that listed species and designated critical habitats may be present in the vicinity of the application of cyhalofop-butyl. This screening level assessment will allow EPA to focus its future evaluations on the types of species where the potential for effects exists once the scientific methods being developed by the agencies have been fully vetted. This screening-level risk assessment for cyhalofop-butyl indicates potential risks of direct effects to listed mammals, birds, terrestrial invertebrates, fish, and aquatic invertebrates on all of its registered use sites. Listed species of aquatic and terrestrial plants may also be affected through indirect effects because of the potential for direct effects on listed and non-listed species upon which such species may rely. Potential direct effects on listed mammals, birds, terrestrial invertebrates, fish, and aquatic invertebrates from the use of cyhalofop-butyl may be associated with modification of Primary Constituent Elements (PCEs) of designated critical habitats, where such designations have been made. Once the agencies have fully developed and implemented the scientific methods necessary to complete risk assessments for endangered and threatened (listed) species and their designated critical habitats, these methods will be applied to subsequent analyses for cyhalofop-butyl as part of completing this registration review.
5.4. Risk Conclusions 

## Risk conclusions are summarized as follows: - The primary risk concern for cyhalofop-butyl is to non-target plant species located in areas that receive spray drift (i.e., those that are adjacent to treated rice paddies). • Risks of concern for plants resulting from spray drift of aerial and ground applications may extend > 1000 feet and 600 feet, respectively, from the edge of the treated field. • If applications are made using nozzles that generate medium or coarse droplets, risks would not extend as far from the edge of the field (based on AgDRIFT model runs with alternate droplet spectra). • It is assumed that granular formulations do not drift from the treated field and therefore do not pose a risk to non-target plants.

Page 34 of 48

## o Although seedling emergence and vegetative vigor toxicity data do not suggest that cyhalofop-butyl or cyhalofop-acid will impact dicots, available incident reports and spray drift buffer restrictions for peaches and nectarines (24 miles for aerial applications, 600 feet for ground) suggest that there may be impacts to non-grass species of plants (e.g., other monocots, dicots). o Risks to specific listed species of terrestrial and wetland plants are uncertain at this time. Cyhalofop-butyl residues on mammalian food items located on the treated field (f.e., grass, broadleaf plants and invertebrates) may pose a chronic risk to mammals consuming those food items. o There is uncertainty associated with the conclusion that exposures to cyhalofop-butyl will impact mammals because: 1) cyhalofop-butyl is not particularly persistent in the environment; therefore, mammals feeding on the treated field may not consume cyhalofop-butyl residues for a sufficient amount of time to represent a chronic exposure; 2) the magnitude of the effect to mammals was only 5-7% decrease in body weight of the F1 generation; although this was a statistically significant effect; the biological relevance of this effect is uncertain and 3) there is uncertainty associated with the NOAEC due to a 10-fold spacing between the NOAEC and the LOAEC. o Risks to listed mammals are uncertain at this time. On the day of the application, concentrations of cyhalofop-butyl in the rice paddy water may be sufficient to pose a risk of mortality to fish and aquatic invertebrates located within the rice paddy. o This would only apply to situations where cyhalofop-butyl is applied to rice paddies that contain water inhabited by aquatic life. This assessment indicates that cyhalofop butyl does not pose a risk of concern to: o Birds, terrestrial-phase amphibians and reptiles; o Terrestrial invertebrates; o Fish and invertebrates in non-target areas; and o Aquatic plants. No Effect determinations may be made for listed species of birds, amphibians, reptiles, invertebrates, fish and aquatic plants that do not depend upon plants or mammals (e.g., for food, habitat). Given that many species depend upon terrestrial, wetland and riparian vegetation for food or shelter, No Effect determinations will be limited to a only a small proportion of all of the currently listed species (e.g., cave-dwelling species of animals).

6. Literature Cited 

## United State Department of Agriculture (USDA). 2012. Rice: Background, U.S. Rice Production.

htti2://www.ers.tisda.gov/tol2ics/crops/rice/backp-rouiid.aspx 

## (Date Accessed: July 30, 2014). Economic Research Service. Washington, DC. United States Environmental Protection Agency (USEPA). 2007. Guidance for Tier 1 Estimation of Aqueous Pesticide Concentrations in Rice Paddies. Memo from S. Bradbury to Environmental Fate and Effects Division; May 8, 2007. U.S. Environmental Protection Page 35 of 48

## Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide

Programs, Environmental Fate and Effects Division, Washington, DC. Available at littp://www.el2a.

~



## i

, 

## ov/ol2l2efed l/models/water/#rice 

## (accessed July 30, 2014). USEPA. 2008. Drinking Water Assessment for the Section 3 Registration of Cyhalofop-butyl for Use of Wild Rice in California. Memo from Katrina White to Daniel Rosenblatt; DP Barcode 357419; October 17, 2008. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division, Washington, DC. USEPA, 2014. BEAD Chemical Profile (BCP) for Registration Review: Cyhalofop-butyl (082583). 

## Memo from Biological and Economic Analysis Division (7503P) to Environmental Fate and Effects Division; May 7, 2014. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Biological and Economic Analysis Division, Washington, DC. United States Geological Survey (USGS), 2011. Pesticide Use Maps: Estimated Agricultural Use for Cyhalofop, 2011. littp://water.usgs.gov/nawqa/pnsp/usa: .>e/maps/sthow map.php?veat=201I&map=CYHAL OFOP&hilo=L&disp=Cyhalofop 

## (Date Accessed: July 30, 2014). U.S. Department of the Interior. Washington, DC.

Page 36 of 48U

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## Appendix C. llescription of niodified Tier I I2ice model



## The Environmental Fate and Effects Division (EFED) developed the screening level Tier I Rice model (i.e. an equation) to estimate pesticide concentration residues in surface waters of 

## floodcd rice fields (USEPA, 2007). The Tier I Rice Model is expressed in the following equation: Equation 1: C,- = mei' /(0.00105 + 0.00013 x Kd)

where; CW 

## = the paddy water concentration (μg/L) 

## m 8 i' 

## = the application rate (kg/hectare) Kd = the soil-water distribution coefficient in L/kg Tier I Rice Model Modifred with Aerobic Aquatic Degradation The Tier I Rice Model was provisionally modified to estimate pesticide residues in surface water discharged from rice fields (e.g. tail water) following a retention period and allowing aerobic aquatic degradation. Incorporating the aerobic aquatic degradation pathway into the Tier I Rice model was used to identify: 1) acute (peak) concentrations following single, or sequential-applications; 2) acute concentrations after the label "recommended" pesticide retention 

## periods (for either single or sequential application scenarios); and, 3) chronic (annual mean) exposure. The moditied Tier I Rice Model includes the additional equation: Lquation 2: C,, , , c= CW, 

## o e("kt)

where; Cw, t= the concentration in water at time, t(μg/L) Cw, 0= the concentration in water at application or time of zero 

## (μg/L) (calculated using the Tier I Rice Model) k= the aerobic aquatic metabolism rate constant (d' 1 ) 

## t = days after application (d)

Page 45 of 48

## Appendix D: Summary of Major and Minor llegradates

'I'abte 15: Sun;ltnary c 3'rnajur ancl miuor de[;radates cat'cyt alofr. p-lyutyf and the range of nlaximurrl percent ofa p iied ec ui'valents in def*rr cfation stucties" (US EPA, 2008; Dl' C3.zreo(fe 3

~~ 

## 7-419). Degradate Names Maximum % SMILES String applied Structure e uivalertts Ma'or Dc radates Made u>10%, of a>>lied parent e uivalents Cyhalofop-acid (CAS No. 122008-78-0); 1.2 — 98.7 

### (R-(+)-2-[4-(2-fluoro-4-cyanophenoxy)phenoxy]propanoic acid); XRD-537 acid; 

### (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid SMILES String: CC(OC1=CC=C(OC2=C(F)C(=CC=C2)C#N)C=C1)C(0)=0 

## O

~ 

## C\ F / O O H 

# I I
~ 

## ` CH 3 ~ 

## \ H O Cyhalofop—amide (CAS No. Unavailable); 1.9 - 44.5 

### (2-[4-(4-aminocarboxyl-2-fluorophenoxy)phenoxy]propanoic acid); XRD-537 a nide; 2-[p-(4-carbamoyl-2-fluorophenoxy)phenoxy]propionic acid; 2-[4-[4-(aminocarbonyl)-2-fluorophenoxy]phenoxyl]propanoic acid; SMILES String: CC(OC1=CC=C(OC2=C(F)C=C(C=C2)C(N)=0)C=C1)C(0)=O O O

F 

### Ni 2 O OH
CH 3 

### ~ Cyhalofop-diacid (CAS No. Unavailable); 11.9 — 86.5 

### (R-(+)-2-[4-(4-carboxy-2-fluorophenoxy)phenoxy]propanoic acid); XRD-537 diacid; 

### 4-[p-(1-carboxyethoxy) phenoxy]-3-fluorobenzoic acid;4-[4-(I-carboxyethoxy)phenoxy]-3- fluorobenzoic acid SMILES String: CC(OC1=CC=C(OC2=C(F)C=C(C=C2)C(0)=0)C=C1)C(0)=0 

### O O

F 

## HO O ~ 

# OH I ` I ~ CH 3 ~ \ H O



## Page 46 of 48

### Degradate Names Maximum %

SMILES String applied 

### Structure e uivalents FHPBA (CAS No. Unavailable); 0.2 — 20.3 3-fluoro-4-(4-hydroxyphenoxy)benzoic acid 

# O F HO 

## ~ / OH 

# I I / O \ DP or FCPP; 0.4 -12.0 (4-(2-fl uoro-4-eyanophenoxy)phenol); 

### XRD-537 DP; 3-fluoro-4-(4-hydroxyphenoxy)benzonitrile 

# No C ~ F 

# / OH I I O Minor De radates made u<10% of applied parent e uivalents 

### HPPA; 0.14 - 7.7 (R-(+)-2-(4-hydroxyphenoxy)propanoic acid); (2R)-2-(4-hydroxyphenoxy)propanoic acid



# O

~ O 

# I OH
OH / FHB; 0.19 — 0.37 (3-fluoro-4-hydroxybenzonitrile); 

### XRD-537 HBN 

# / \ F 

# N I

~ OH



## Page 47 of 48

## Appendix E. Example lines of evidence for deriving risk conclusions and their certainty Conclusion: No Risks of Concern Conclusion: Risks of Concern Identified Certain in : 

## Hi h Certaintv: Hi 

## h

• High magnitude and/or long duration
• More than one line of evidence predicts effects will occur
• No LOC exceedance with relatively complete data • LOC exceedances, fate, and toxicity profile should set or risks have been mitigated; be considered
• High confidence in data • Exposure is expected to occur based on fate profile
• Fate and toxicity profiles clearly support low risk and uses
• Probable cause of incident(s).
• Examples: High toxicity, high persistence, incident(s), little exposure needed to cause effects Conclusion: No Risks of Concern Conclusion: Risks of Concern Identiried

Certaint : Low Certaintv: Low

• Chronic risk called for non-persistent chemical
• No LOCs exceeded but other non-compelling • Risk to taxonomic group called based on complete circumstances suggest that there may be issues lack of submitted data
• Missing endpoints, poorly spaced test • Risk calls based on lack of data without other lines concentrations, low confidence in data showing of evidence available low toxicity • Risk calls based on uncertain extrapolation
• Lack of LOC exceedances based on extrapolation methods or conflicting data and additional information is being requested to • Missing endpoints, poorly spaced test corroborate low risk concentrations, low confidence in data showing
• Examples: high persistence and bioaccumulation, high toxicity but low risk calls • Examples: Risk calls based on total residues, but not parent only (sometimes)



## Page 48 of 48