Docket Number EPA-HQ-OPP-2007-1089 

www.regulations.gov 

Quizalofop-ethyl 

Quizalofop-p-ethyl 

Interim Registration Review Decision 

Case Number 7215 

December 2014 

Approved by: ~'kYZ-= f' ~'"1.AA,.:p Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

Date: ld/1~/~, o! L-/-
Table of Contents 

Contents 

I. INTRODUC'fiON .............. ........ .... .................................. .... ................................................... 3 

II. USE AND USAGE ................... ................................................... ........................................... 6 

III. SCIENTIFIC ASSESSMENTS ............................................................................................... 6 

A. Human Health Assessment .................................................................................................... 6 

1. Risk Estimates ........................................................ .... ........ .......................................... 6 

2. Human Incidents .................................... ....................................................................... 7 

3. Food Tolerances ........................................................................................................... 8 

4. Data Needs ........................................................................................ 7 

B. Environmental Assessment. ..... ............................ .................... .......... ............. 7 

1. Environmental Fate and Exposure ............................................................. 7 

2. Ecological Risk Estimates ............................................................................................ 9 

3. Ecological Incidents ................................................................................................... 13 

4. Ecological Risk Characterization for Non-Listed Species ........................ ... .. .... 11 

Endangered Species Assessment .......................................................................................... 15 

Endocrine Disruptor Screening Program .............................................................................. 15 

IV. INTERIM REGISTRATION REVIEW DECISION ............................................................ 17 

V. NEXT STEPS AND TlMELINE .......................................................................................... 19 

References ................................ . ................... . .... .. .... .. ................ .. .. .. ... .. ......... 18 

Appendix A: Summary of Actions Taken for Quizalofop ...................................... ..... ..... ........... 21 

Appendix B: Quizalofop Label Table ........................................................ ..................... ............. 20 

2 
I. INTRODUCTION 

This document is the Environmental Protection Agency's (EPA or the Agency) Interim 

Registration Review Decision for quizalofop, which appears as two different isomer mixtures: 

quizalofop-ethyl (PC code 128711) and quizalofop-p-ethyl (PC code 128709) and is being issued 

pursuant to 40 CFR sections 155.56 and 155.58 (case 7215). A registration review decision is the 

Agency's determination whether a pesticide meets, or does not meet, the standard for registration 

in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, 

when it determines it to be appropriate, an Interim Registration Review Decision before 

completing a registration review. Among other things, the Interim Registration Review Decision 

may: 1) require new risk mitigation measures; 2) impose interim risk mitigation measures; 3) 

identify data or information required to complete the review; and 4) include schedules for 

submitting the required data, conducting the new risk assessment and completing the registration 

review. For further information on quizalofop, additional documents can be found in EPA's 

public docket (EPA-HQ-OPP-2007-1089) at www.regulations.gov. 

FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the 

continuous review of existing pesticides. All pesticides distributed or sold in the United States 

generally must be registered by the EPA based on scientific data showing that they will not cause 

unreasonable risks to human health or to the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

and reduce risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the registration review 

program, the Agency periodically re-evaluates pesticides to make sure that as these changes 

occur, products in the marketplace can continue to be used safely. Information on this program is 

provided as www.epa.gov/oppsrrd 1/registration review/. 

In 2006, the Agency implemented the registration review program pursuant to FIFRA 

section 3(g) and will review each registered pesticide every 15 years to determine whether it 

continues to meet the FIFRA standard for registration. 

The first pesticide product containing quizalofop-ethyl was registered in 1988 and the 

first pesticide product containing quizalofop-p-ethyl was registered in 1990. Quizalofop was not 

subject to reregistration because products containing it were first registered after November 

1984. 

Pursuant to 40 CFR section 155.50, EPA formally initiated registration review for 

quizalofop (case 7215). The following highlights are significant events that have occurred during 

the registration review of quizalofop and can be found in the public docket (EPA-HQ-OPP-2007-

1 089, accessed at www.regulations.gov): 

• December 19, 2007 - Publication of the quizalofop Summary Document for a 60-day 

public comment period. The Summary Document included the Preliminary Work Plan 

(PWP) and was accompanied by the scoping document and problem formulation. Four 

public comments were received during the 60-day comment period for the quizalofop 

PWP. 

3 
• June 12, 2008- Final Work Plan (FWP) for quizalofop was issued. During the comment 

period, the Agency re-evaluated certain ecological effects data and made changes to the 

quizalofop work plan. The FWP modified the PWP to include additional anticipated 

aquatic plant toxicity testing (GLN 850.4400) and aquatic emergent testing on rice 

(Special Protocol). The FWP also removed the anticipated data requirement for chronic 

early life-cycle toxicity testing on estuarine marine invertebrates (GLN 850.1350). 

• December 16, 2009- Generic Data Call-In Notice (GDCI) for quizalofop was issued. 

• March 20, 2013 - The Agency placed in the docket the Registration Review-Ecological 

Risk Assessment and Effects Determination of Quizalofop-p-ethyl and the Quizalofop 

Ethyl and Quizaiofop-p-ethyl, Summary of Human Health Risk Assessment for 

Registration Review for a 60-day public comment period. During that time, one 

submission was received from DuPont De Nemours and Company, but the comments did 

not result in revisions to the risk assessments. 

• March 14, 2014 - The Agency published the Response to Public Comments on the 

Quizalofop (PC: 12871 1) and Quizalofop-p-ethyl (PC: 128709) Registration Review 

Preliminary Risk Assessment and Quizalofop Ethyl and Quizalofop-p-ethyl, Response to 

Comments on the Human Health Risk Assessment for Registration Review. 

• July 18, 2014 - The Agency published the Quizalofop Proposed Interim Registration 

Review Decision in docket number EPA-HQ-OPP-2007-1 089 for a 60-day public 

comment period. The Agency also published an addendum to the environmental fate and 

ecological risk assessment for quizalofop, titled "Refinements to the Quizalofop 

Preliminary Risk Assessment in Support of Registration Review" . The addendum refmes 

the original risk assessment and adds further risk characterization. The Agency received 

comments from the Center for Biological Diversity. The comments addressed the 

Agency's duty under the Endangered Species Act (ESA) to consult with the US Fish and 

Wildlife Service and the National Marine Fisheries Service (the Services) on the 

registration review of quizalofop. 

Public Comments 

One public comment from the Center for Biological Diversity was submitted to the 

Agency during the 60 day public comment period for the Quizalofop Proposed Interim Decision. 

The comment addressed the Agency's responsibilities under the Endangered Species Act (ESA). 

The comment is summarized herein along with the Agency's response. The Center for 

Biological Diversity's comment in its entirety is located in the quizalofop registration review 

docket (EPA-HQ-OPP-2007 -1 089) at www.regulations.gov. 

Comments submitted by the Center for Biological Diversity in EPA-HQ-OPP-2007-1089-

0041. 

Comment: The Center for Biological Diversity 's (CBD) comments focus on the EPA 's 

independent duty under the Endangered Species Act (ESA) to consult with the U.S. Fish and 

4 
Wildlife Service and the National Marine Fisheries Service (the Services) on the registration 

review ofquizalofop. 

Agency Response: EPA has reviewed the comments from CBD on the Quizalofop Proposed 

Interim Decision and plans to address many of the concerns raised by CBD as part of the 

implementation plan for assessing the risks of pesticides to listed species based on the 

recommendations ofthe April2013 National Academy of Sciences (NAS) report. EPA will 

address concerns specific to quizalofop in connection with the development of its final 

registration review decision for quizalofop. 

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 1 5, 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 April 

2014, allowing 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 1, 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, the ecological risk assessment supporting this Interim Registration 

Review Decision for quizalofop 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 quizalofop. 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. While the agencies continue to develop a common method for ESA analysis, 

the regulatory section of the Interim Registration Review Decision document will describe the 

level of ESA analysis completed for this particular registration review case. Once the agencies 

5 
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 quizalofop as part of completing this 

registration review. 

II. USE AND USAGE 

Quizalofop is a selective post-emergence herbicide. Quizalofop appears as two different 

isomer mixtures: quizalofop-ethyl and quizalofop-p-ethyl. Quizalofop-p-ethyl is composed 

solely of the pesticidally active isomer, and all quizalofop products currently in the marketplace 

contain this isomer; there are no pesticide registrations for products containing quizalofop-ethyl 

(a 50/50 racemic mixture of active and inactive isomers). Both quizalofop-p-ethyl and 

quizalofop-ethyl are referred to collectively as quizalofop. 

Quizalofop is a systemic herbicide registered for use to control annual and perennial 

weeds in various food/feed and non-food/non-feed crops. Food and feed uses include grains, 

legumes, cotton, garlic, mint, soybean, sugar beets, sunflower, pineapple, and Chinese cabbage. 

Non-food/non-feed uses include cottonwood and poplar plantations and uncultivated areas such 

as fencerows, roadsides, and paved areas. There are no registered residential uses of 

quizalofop. An estimated average of 53,500 lbs of quizalofop (averaged from 2003-201 0) is 

applied on agricultural crops in the U.S. each year. The majority is applied to dry beans/peas and 

soybeans (approximately 20,000 lbs each). Other minor usage commodities are sunflowers 

(approximately 4,000 lbs), sugar beets (approximately 3,000 lbs), canolalrapeseed 

(approximately 2,000 lbs), alfalfa and cotton (approximately 1,000 lbs each), as well as barley, 

green beans, garlic, onions, and green peas (<500 lbs each). The Agency does not have usage 

estimates for non-agricultural use sites. 

III. SCIENTIFIC ASSESSMENTS 

A. Human Health Assessment 

The HED seeping document, its supporting documents, and the most updated Agency 

science policies and risk assessment ·methodologies were used to prepare a quantitative risk 

assessment in support of the registration review of quizalofop. The most recent human health 

risk assessment was conducted in 2011 to assess new uses on various crops. For a detailed 

discussion, see the Quizalofop Ethyl and Quizalo.fop-p-ethyl, Summary of Human Health Risk 

Assessmentfor Registration Review, dated December 11,2012 in the public docket EPA-HQOPP-2007-1 089, which can be accessed on http://www.regulations.gov/. 

1. Risk Conclusions 

Dietary Exposure Assessment 

An acute dietary risk assessment was not performed because toxicity was not observed 

following a single dose of quizalofop. Similarly a cancer risk assessment was not performed 

6 
because quizalofop is classified as Category D, not classifiable as to human carcinogenicity. A 

screening-level chronic dietary risk assessment was performed that included both food and 

drinking water. Children l-2 years old were found to have the highest chronic dietary risk 

estimate at 29% of the chronic population adjusted dose (cPAD), which is well below the 

Agency's level of concern of 100% ofthe cPAD. All other population subgroups had chronic 

dietary risk estimates below that estimated for children 1-2 years old. 

Residential Exposure Assessment 

Since quizalofop is not registered for use in residential settings, a residential assessment 

was not performed for registration review. 

Aggregate Exposure Assessment 

Aggregate risk estimates take into account both dietary (food and drinking water) and 

residential sources of exposure. Since quizalofop is not registered for residential use, the 

aggregate assessment for quizalofop included only food plus drinking water exposure estimates 

and were not different than those described above. 

Cumulative Effects 

Section 408(b)(2)(D)(v) ofthe Federal Food, Drug, and Cosmetic Act (FFDCA) requires 

the Agency to consider the cumulative effects of exposure to quizalofop and other substances 

that have a common mechanism of toxicity. These considerations include the possible 

cumulative effects of such residues on infants and children. 

EPA has not made a common mechanism oftoxicity finding for quizalofop and any other 

substances, and quizalofop does not appear to produce a toxic metabolite produced by other 

substances. Therefore, EPA has not assumed that quizalofop has a common mechanism of 

toxicity with other substances and a cumulative effects assessment was not performed. 

Occupational Exposure Assessment 

The occupational exposure assessment estimates risk to workers in an occupational 

setting via the dermal and inhalation routes of exposure. Quizalofop is not toxic via the dermal 

route according to available dermal toxicity data and therefore a dermal endpoint was not 

selected for risk assessment. Quizalofop has low toxicity via the inhalation route and it is not 

volatile, and therefore inhalation exposures of concern are not expected. To support this low 

hazard estimation, the Agency performed a screening-level assessment to estimate inhalation 

exposure risk for workers applying and handling quizalofop products for a number of high 

acreage crops. Risk estimates were not of concern with margins of exposure (MOEs) estimated 

to range from 2,900 to 211,000 (with MOE of I 00 as the level of concern). 

2. Human Incidents 

For this registration review, an initial incident search was conducted in 2007 and an 

updated search was conducted in 2012. Eight quizalofop incidents were identified in the 

7 
Incident Data System (IDS) from 1999 to 2012; these incidents were associated with symptoms 

including rashes, cramping, swelling, diarrhea, nausea, dizziness, lethargy, and hypothermia. Ten 

incidents were identified from the Poison Control Center Data from 1993 to 2005; effects 

reported were headaches, eye irritation, and throat irritation. Three cases associated with one 

drift event in 2005 were identified in the National Institute of Occupational Safety and Health 

(NIOSH) Sentinel Event Notification System for Occupational Risks (SENSOR) from 1998 to 

2008. The three cases were classified as low in severity. There is not a concern at this time 

based on the continued low frequency and severity of incident cases for quizalofop. For 

additional details, please refer to Review ofQuizalofop Incident Reports in docket EPA-HQOPP-2007-1089, which can be accessed at www.regulations.gov. 

3. Food Tolerances 

Tolerances for residues of quizalofop on food are established in 40 CFR § 180.441. 

Maximum residue limits (MRLs) for quizalofop have not been established by Mexico or Codex. 

The Canadian and U.S. residue definitions for quizalofop are similar but not identical. The 

Agency will pursue harmonizing certain tolerances with Canadian MRLs during registration 

review; these are summarized in Table 2 of the Quizalofop Ethyl and Quizalofop-p-ethyl, 

Summary of Human Health Risk Assessment for Registration Review. 

4. Data Needs 

The following residue chemistry data were identified as data gaps from other registrationrelated actions: 

1) Guideline 860.1360- Multiresidue methods 

2) Guideline 860.1380- Storage stability 

3) Guideline 860. 1520-Processed food and feed 

4) Guideline 860.1650-Analytical reference standards 

Since the publication of the 2012 human health risk assessment, the Agency has received studies 

to support guidelines 860. 1380 and 860.1520. Guidelines 860.1360 (multiresidue methods) and 

860. 1650 (analytical reference standards) remain as data gaps for quizalofop. Since these studies 

are meant to support a new use registration on sunflower, these data gaps do not impact the 

registration review human health risk assessment for quizalofop. 

In addition to the listed data gaps, the Agency believes that the grazing restriction on the 

Assure II label (EPA Registration Number 352-541) is impractical for barley and wheat and 

should be removed to improve clarity (please see the document titled Quizalofop-p-ethyl. Data 

Call-In in Support of the Condition of Registration.for Use on Sunflower (PP#OF6076) and 

Summary of Analytical Chemistry and Residue Data to Support Registration Review, located in 

the quizalofop registration review docket EPA-HQ-OPP-2007-1 089, for additional information). 

The label currently indicates that grazing of livestock is prohibited in treated areas. 

8 
B. Environmental Assessment 

For non-listed species, the Agency identified no risk concerns for birds, reptiles, and 

terrestrial-phase amphibians, terrestrial invertebrates, terrestrial dicots, estuarine/marine fish, 

freshwater invertebrates, estuarine/marine invertebrates and aquatic plants. However, potential 

risks were identified for non-listed mammals, terrestrial monocots, and freshwater fish ~nd 

aquatic-phase amphibians. These risks are summarized below. For detailed discussions of all 

aspects of the environmental risk assessment, see the Registration Review-Ecological Risk 

Assessment and Effects Determination ofQuizalofop-p-ethyl, dated February 19, 2013, and 

subsequent Refinements to the Quizalofop Preliminary Risk Assessment in Support of 

Registration Review, dated March 20,2014, in the public docket (EPA-HQ-OPP-2007-1089) 

which can be access.ed on http://www.regulations.gov/. 

The Agency also completed a screening-level endangered and threatened (listed) species 

assessment for quizalofop and identified potential risks to several taxa (mammals, freshwater 

fish (surrogate for aquatic-phase amphibians), freshwater invertebrates, estuarine/marine 

invertebrates, and monocots). The Agency is currently working with its federal counterparts and 

other stakeholders to implement an interim approach for assessing potential risk to listed species 

and their designated critical habitats. Once the scientific methods necessary to complete risk 

assessments for listed species and their designated critical habitats are finalized, the Agency will 

complete its endangered species assessment for quizalofop. As such, only screening-level risks 

to listed species will be enumerated here. Risks to listed species will not be characterized herein. 

1. Environmental Fate and Exposure 

Quizalofop-p-ethyl is relatively stable to hydrolysis and stable to photolysis in water and 

soil. Quizalofop-p-ethyl degrades to quizalofop acid, 3-0H-quizalofop acid, and phenolic 

compounds. Quizalofop acid and 3-0H-quizalofop acid are degradates of concern for aquatic 

exposures. Quizalofop acid appears to be less persistent than the parent, quizalofop-p-ethyl, and 

3-0H-quizalofop acid under aerobic conditions; but both are moderately mobile. The toxicity of 

quizalofop-p-ethyl, quizalofop acid, and 3-0H-quizalofop are considered roughly equivalent for 

ecological risk assessment, which is a conservative assumption. The fate and effects data are 

largely available only for the parent chemical, quizalofop-p-ethyl. Therefore a total toxic 

residues (TIR) approach was used to adjust exposure half-lives to account for the duration of 

exposure to all three chemicals of concern. 

2. Risk Conclusions 

Risk to Terrestrial Organisms 

Direct effects to terrestrial organisms are listed below. The Agency identified direct 

effects to mammals and terrestrial and wetland/riparian plants. The Agency has not made an 

effects determination for listed terrestrial birds, reptiles, terrestrial-phase amphibians, mammals, 

terrestrial invertebrates, and terrestrial and wetland/riparian plants at this time and will address 

risks to listed species at a later stage of registration review. The Agency is making a "no effect" 

determination for non-vascular aquatic plants because there are currently no listed non-vascular 

aquatic plants (please see the document titled Registration Review-Ecological Risk Assessment 

9 
and Effects Determination ofQuizalofop-p-ethyl for additional information on all risk 

conclusions). 

Birds, Reptiles, and Terrestrial-Phase Amphibians . 

Acute dose-based and dietary-based risk quotients (RQs) could not be calculated to 

evaluate risk because only non-definitive acute toxicity data were available. To estimate acute 

risks to birds, reptiles, and terrestrial-phase amphibians, the non-definitive toxicity values were 

directly compared to the estimated environmental concentrations (EECs) and found to be not of 

concern. Therefore, the potential for risk is considered to be low for acute dose-based and 

dietary-based exposure of birds, reptiles, and terrestrial-phase amphibians from quizalofop for all 

registered uses. 

Chronic dietary-based RQs were calculated for the maximum application rates of 

quizalofop for all uses. RQs ranged from 0.01 to 0.52, and none of the uses exceeded the 

Agency's chronic level of concern (LOC) of 1. Thus, chronic effects to birds, reptiles, and 

terrestrial-phase amphibians are considered unlikely. 

The risk assessment thus did not identify direct effects to listed or non-listed terrestrial 

birds, reptiles, and terrestrial-phase amphibians. 

Mammals 

Acute dose-based RQs were calculated for the maximum application rates for all 

quizalofop uses. RQs ranged from <0.01 to 0.05. None of the uses produced RQs above the 

Agency's listed species LOC of 0.1. Therefore, acute effects to listed and non-listed mammals 

are not expected. 

RQs were calculated for dietary and dose-based chronic exposures. Chronic dietarybased RQs ranged from 0.01 to 0.93 and none of the uses exceeded the Agency's chronic LOC 

of 1. However, chronic dose-based RQs ranged from 0.01 to 8.10 and all uses had multiple 

scenarios that exceeded the Agency's chronic LOC of I. The highest chronic dose-based RQs 

were for use on pineapple in Puerto Rico and Hawaii, and use on ornamentals and shade trees. 

Therefore, there is the potential for chronic risk to both listed and non-listed mammals for all 

quizalofop uses. 

The risk assessment thus identified only chronic risk to both listed and non-listed 

mammals. 

Terrestrial Invertebrates 

Only non-definitive honeybee toxicity data were available. Consequently, the highest 

EEC was compared with the acute contact LDso value for the honeybee and found to be lower. 

Therefore, based upon qualitative analysis, the potential for acute risk to both listed and nonlisted terrestrial invertebrates is not expected. 

10 
Direct effects to listed and non-listed terrestrial insects are not expected. 

Terrestrial and Wetland/Riparian Plants 

Dicots did not exceed the Agency's LOC of 1 for any scenario modeled. For ground 

applications, RQs ranged from <0.01 to 0.18. For aerial applications, RQs ranged from 0.01 to 

0.25. Therefore, listed and non-listed dicots are not expected to be at risk from any of the 

registered quizalofop uses. 

Monocots were more sensitive than dicots to quizalofop and there is potential for direct 

effects to listed and non-listed monocots. All ground and aerial spray drift scenarios exceeded 

the Agency's LOC of 1. Ground application RQs ranged from <0.0 1 to 1.42 and aerial 

application RQs ranged from 0.11 to 13.15. Therefore, there is the potential for direct effects to 

listed and non-listed terrestrial monocots for all registered uses of quizalofop. 

Direct effects to listed and non-listed dicots are not expected since RQs did not exceed 

the LOC of 1. Direct effects to listed and non-listed monocots are expected as RQs exceeded the 

LOC of 1. 

Risk to Aquatic Organisms 

Direct effects to aquatic organisms are listed below. The Agency identified direct effects 

to freshwater fish and aquatic-phase amphibians. The Agency has not made an effects 

determination for listed freshwater fish, aquatic-phase amphibians, estuarine/marine fish, 

freshwater invertebrates, estuarine/marine invertebrates, and aquatic vascular plants at this time 

and will address risks to listed species at a later stage of registration review. 

Freshwater Fish and (Aquatic-Phase) Amphibians 

Acute RQs for freshwater fish (surrogate for aquatic-phase amphibians) ranged from 

0.001 to 0.028 and did not exceed the Agency's listed species LOC of0.05 for any ofthe 

registered quizalofop uses. Therefore, adverse effects to listed and non-listed freshwater fish on 

an acute exposure basis are not expected for registered uses of quizalofop. 

Chronic RQs for freshwater fish (surrogate for aquatic-phase amphibians) ranged from 

0.069 to 1.86. Two uses exceeded the chronic LOC of 1: pineapple (ground and aerial), and 

paved areas (ground and aerial). The RQs for all other quizalofop uses were below the chronic 

LOC of 1. 

Acute effects to listed and non-listed freshwater fish and aquatic-phase amphibians are 

not expected since RQs were below the listed species LOC of0.05. Chronic RQs exceeded the 

chronic LOC of 1, therefore, chronic risk to listed and non-listed freshwater fish and amphibians 

is expected. 

11 
Estuarine/Marine Fish · 

Acute data were not available for estuarine/marine fish; however, the freshwater fish 

acute data were determined to be sufficiently protective to use as a surrogate. As with the 

freshwater fish, acute RQs for estuarine/marine fish ranged from 0.001 to 0.028 and did not 

exceed the listed species LOC of 0.05 for any of the registered quizalofop uses. Therefore, 

adverse effects to listed and non-listed estuarine/marine fish from the registered uses of 

quizalofop-p-ethyl are not expected on an acute exposure basis. 

Chronic RQs ranged from 0.007 to 0.224 and did not exceed the Agency's chronic LOC 

of 1. Therefore, adverse effects to listed and non-listed estuarine/marine fish are not expected 

from the registered uses of quizalofop on a chronic basis. 

Direct acute effects to listed and p.on-listed estuarine/marine fish are mot expected since 

acute RQs were below the listed species LOC of 0.05. Chronic effects to listed and non-listed 

estuarine/marine fish are not expected since the chronic RQs did not exceed the chronic LOC of 

l. 

Freshwater Invertebrates 

Acute RQs for freshwater invertebrates ranged from 0.002 to 0.057. No uses exceeded 

the non-listed species LOC of0.5. However, acute RQs exceed the listed species LOC of0.05. 

Chronic RQs for freshwater invertebrates were all <0.001. None of the RQs exceeded the 

chronic LOC of 1 for any registered use of quizalofop. 

Direct effects to listed freshwater invertebrates are expected on an acute basis since acute 

RQs exceed the listed species LOC of 0.05. Chronic direct effects to listed and non-listed 

freshwater invertebrates are not expected since RQs were below the chronic LOC of 1. 

Estuarine/Marine Invertebrates 

Acute RQs for estuarine/marine invertebrates ranged from 0.004 to 0. 133. No uses 

exceeded the non-listed species LOC of0.5. However, RQs for two uses exceeded the acute 

listed species LOC of 0.05: pineapple (ground and aerial), and paved areas (ground and aerial). 

Chronic RQs for estuarine/marine invertebrates ranged from 0.002 to 0.057. None of the 

RQs exceeded the chronic LOC for I for any registered use of quizalofop. 

Direct acute effects to listed estuarine/marine invertebrates are expected on an acute basis 

as acute RQs exceed the listed species LOC of 0.05 for two uses. Direct chronic effects to listed 

and non-listed estuarine/marine invertebrates are not expected since RQs were below the chronic 

LOC ofl. 

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Aquatic Vascular and Non-vascular Plants 

Aquatic vascular plant RQs ranged from 0.015 to 0.580. Aquatic non-vascular plant RQs 

were all <0.00 I. None of the aquatic plant RQs exceeded the LOC of 1 for any registered use of 

quizalofop. 

Direct effects to listed and non-listed aquatic vascular and non-vascular plants are thus 

not expected as RQs did not exceed the LOC of 1. 

3. Ecological Incidents 

According to a search conducted for quizalofop on September 26, 2012, using the 

Ecological Incident Information System (EllS), one major and one minor incident were reported 

for quizalofop from 1988 to 2012. The major incident occurred when spray drift from an 

application of quizalofop and sodium fomesafen to soybeans impacted home gardens. The minor 

incident was associated with minor plant damage. For additional details, please refer to 

Registration Review-Ecological Risk Assessment and Effects Determination of Quizalofop-pethyl, dated February 19,2013 in docket EPA-HQ-OPP-2007-1089, which can be accessed at 

www.regulations.gov. 

4. Ecological Risk Characterization for Non-Listed Species 

Ecological risk estimates for quizalofop represent screening-level analysis where the 

Agency uses reasonable worst-case scenarios and conservative assumptions with the intention 

that estimates do not underestimate risk. EPA has determined that there is potential for adverse 

effects to non-listed mammals and freshwater fish and aquatic-phase amphibians (chronic RQs 

exceed LOCs) as well as non-listed terrestrial and wetland/riparian plants (RQs for monocots 

exceed LOCs) based on its screening-level risk assessment. 

Mammals 

The preliminary ecological risk assessment identified chronic risk to small and medium 

sized mammals consuming short grass from all uses of quizalofop. The assessment also 

identified chronic risk to aJl mammals from use on pineapple and ornamental and/or shade trees. 

Chronic risk to mammals was estimated using a two-generation rat reproduction study in which 

parental, Fl , and F2 generations are exposed to different doses of quizalofop via treated food, but 

the study is not designed to determine the duration of time needed to manifest adverse effects. 

As a result, it was uncertain if adverse effects observed in mammals were the result of short-term 

exposure during a critical development window or longer term exposure. The Agency further 

refined its assessment of chronic risk to mammals by analyzing data from a pre-natal 

development rat study which tested shorter exposure durations (see Refinements to the 

Quizalojop Preliminary Risk Assessment in Support of Registration Review, dated March 20, 

2014). Results suggested that adverse effects (decreased pup survival) were not the result of 

short-term exposure. Consequently, risk to mammals is believed to be low if the exposure 

duration is short (less than 10 days). At the highest application rate (pineapple at 2 applications 

at 0.208 lb ai/A with 7 day intervals), EECs were not high enough to cause adverse chronic 

13 
effects. Since this is true for the highest use rate, on pineapple, it is assumed that it would apply 

to all of the other quizalofop uses with lower application rates. Thus, chronic risk to mammals is 

expected to be low. 

Furthermore, with regard to the chronic risk to large mammals from use on pineapple and 

ornamentaVshade trees, there are a number of factors which the Agency evaluated. Pineapple is 

only grown in very small areas of Puerto Rico and Hawaii, which limits the number of large 

mammal species potentially exposed to quizalofop. Ornamental and/or shade tree production is 

unlikely to occur in areas where large mammals forage, as most production occurs indoors in 

greenhouses or outdoors in large industrial-sized lots in urban/suburban areas. 

Terrestrial and wetland/riparian plants 

Only monocots had RQs that exceeded the LOC. In the risk assessment, conservative 

parameters were chosen to model spray drift from ground applications (maximum application 

rate, high boom, very fine to fine droplet size, 90'h data percentile) and aerial applications 

(maximum application rate, very fine to fme droplet size). When AgDRIFT was rerun with less 

conservative application parameters (increased droplet size, reduced boom height), estimated 

buffer distances were reduced by hundreds of feet (see table 5 of Refinements to the Quizalofop 

Preliminary Risk Assessment in support of Registration Review, dated March 20, 2014). In real 

world scenarios, applicators would be expected to apply quizalofop at larger droplet sizes and at 

application rates suitable to the crop being treated and only when wind conditions were 

favorable. Estimated real world risk to monocots are expected to be less than estimated in the 

Agency's risk assessment, which is necessarily conservative. 

Freshwater fish and aquatic-phase amphibians 

The chronic RQs for freshwater fish (a surrogate for aquatic-phase amphibians) exceeded 

the LOCs for two uses: pineapple and paved areas. The pineapple use is geographically 

restricted to Hawaii and Puerto Rico. The other use, paved areas, is nation-wide. 

The Agency does not believe that risk to freshwater fish/aquatic-phase amphibians are of 

concern because pineapple is grown in very small areas of Puerto Rico and Hawaii. 

Additionally, quizalofop use on pineapple is limited to an even smaller subset of these areas. 

According to the University of Hawaii at Manoa, quizalofop is typically applied at 1 to 2 kglha 

(0.892-1.784lbs/A) on 0.5% of the acreage (Sipes, 2000). 

The paved area scenario was modeled using the conservative assumption that 100% of 

the quizalofop applied to an acre is available for off-site transport. However, realistically, this 

number is likely much lower as quizalofop is being used as a spot treatment for weeds that are 

present in cracks within a paved area. It is unlikely that quizalofop would be applied over an 

entire acre of paved area. 

14 
Endangered Species Assessment 

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 April 

2014, allowing 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 ofthe National Academy of Sciences 

April 2013 Report," dated November 1, 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, the ecological risk assessment supporting this Interim Registration 

Review Decision for quizalofop 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 quizalofop. 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. 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 

quizalofop as part of completing this registration review. 

Endocrine Disruptor Screening Program 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential 

adverse outcomes from exposure to chemicals. Collectively, these studies include acute, 

15 
subehronic 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 part of its most recent registration decision for quizalofop, EPA 

reviewed these data and selected the most sensitive endpoints for relevant risk assessment 

scenarios from the existing hazard database. However, as required by FFDCA section 408(p), 

quizalofop is subject to the endocrine screening part of the Endocrine Disrupter Screening 

Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including 

pesticide active and other ingredients) may have an effect in humans or wildlife similar to an 

effect produced by a "naturally occurring estrogen, or other such endocrine effects as the 

Administrator may designate." The EDSP employs a two-tiered approach to making the 

statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to 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 

potential to interact withE, A, or T hormonal systems will proceed to the next stage of the EDSP 

where EPA will determine which, if any., of the Tier 2 tests are necessary based on the available 

data. Tier 2 testing is designed to identify any adverse endocrine-related effects caused by the 

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

Under FFDCA section 408(p ), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/DCis 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 1 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 disrupters. 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.2 

Quizalofop is on List 2. List 2 represents the next set of chemicals for which EPA intends 

to issue test orders/DCis in the near future. In the interim, EPA is making no human health or 

environmental safety findings associated with the ESDP screening of quizalofop. Before 

completing the registration review, the Agency will make an EDSP FFDCA section 408(p) 

determination. 

1 See http://www.regulations.gov/#!documentOetaii;D=EPA-HQ-OPPT-2009-0477-0074 for the fmal second list of 

chemicals. 

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

16 
IV. INTERIM REGISTRATION REVIEW DECISION 

A. Tolerance Amendments 

Although EPA has determined that there are no adverse human health effects from all 

uses of quizalofop, the Agency will pursue changes to the quizalofop tolerances in the interest of 

harmonization with MRLs for certain commodities established in Canada. 

B. Risk Mitigation Measures and Regulatory Rationale 

The Agency believes there is the potential for adverse effects to non-listed mammals, 

freshwater fish, aquatic-phase amphibians, and terrestrial and wetland/riparian plants. In order to 

address potential ecological effects, the quizalofop technical registrants (DuPont, Nissan, and 

Sharda), based on discussions with the Agency, will amend their affected product registrations 

and labels to incorporate the following risk mitigation measures: 

1) Limit spot treatments and clarify use directions on quizalofop labels for products with 

use on paved areas. 

2) Delete aerial application to pineapple. 

3) Delete aerial application to non-food/non-feed crops and ryegrass crops grown under 

contract for seed production. 

4) Delete aerial application in eucalyptus plantations. 

5) Delete aerial application to hybrid poplar plantings. 

6) Delete aerial application to non-crop areas (such as fence rows, roadsides, equipment 

storage areas, and similar areas). 

7) Include medium/coarse or larger spray droplet size requirements on the labels for all 

ground broadcast applications. 

8) Include coarse or larger spray droplet size requirements on the labels for all aerial 

broadcast applications. 

With the adoption of these risk mitigation measures, the Agency believes that estimated 

risk to non-listed mammals, freshwater fish, aquatic-phase amphibians, and terrestrial and 

wetland/riparian plants are lower (see Appendix A. Summary of Actions Taken for Quizalofop) .. 

Also, in consideration of quizalofop's utility as an herbicide that selectively controls certain 

monocot weeds, it has importance in certain minor use niche markets (e.g. , dry beans/peas, mint, 

pineapple, sunflower, and ornamental trees). 

In addition to the above listed changes, the Agency believes that the grazing restriction 

on the Assure II label (EPA Reg. 352-541) will be removed. The label currently states that 

grazing of livestock is prohibited in treated areas. The removal of this language is meant to 

improve the clarity of the label. 

DuPont, Nissan, and Sharda are currently working with the Agency to revise their 

quizalofop labels to reflect the changes identified above. Below is the regulatory rationale for 

17 
these actions. Proposed amended labels have already been submitted to the Agency for review 

and will be amended as part of registration review. 

Regulatory Rationale 

To reduce spray drift risks to non-target plants, the registrants voluntarily agreed to 

increase the droplet size for both ground broadcast and aerial application. Applicators applying 

quizalofop by ground broadcast equipment will be required by the labels to use application 

. technology that will deliver medium coarse,or larger spray droplets and applicators applying 

quizalofop by air broadcast application will be required to use application technology that will 

deliver coarse or larger spray droplets as defined in the American Society of Agricultural and 

Biological Engineers standard ANSI/ ASAE S572.1. The intended impact of making these 

changes is to reduce the distance that spray droplets will drift from the site of application and 

reduce exposure to non-target plants. 

Furthermore, the registrants have voluntarily agreed to change product labels to remove 

aerial application for some uses: pineapple, non-food/non-feed crops and ryegrass crops grown 

under contract for seed production, eucalyptus plantations, hybrid poplar plantings, and non-crop 

areas (such as fence rows, roadsides, equipment storage areas, and similar areas). These label 

changes are intended to result in reduced off-site transport into terrestrial areas, streams, river, 

lakes, and other water bodies and therefore reduce exposure to non-target plants and freshwater 

fish, aquatic-phase amphibians, and other aquatic organisms. According to the University of 

Hawaii at Manoa, pesticides are usually applied to pineapple crops via ground application with 

truck-mounted boom sprayers (Bartholomew et al., 2002), so this labeling change is unlikely to 

substantially affect pineapple growers. 

For application of quizalofop to paved areas, the Agency believes (and the technical 

registrants agree) that this use is intended to be a spot treatment. However, current labels do not 

define specific applications as spot treatments. The registrants have voluntarily agreed to add 

label language which includes spot treatment directions for all products intended to be used on 

paved areas. Spot treatments will be defined on the quizalofop labels as an application applied to 

less than 10% of the total paved area. Risk to freshwater fish and aquatic-phase amphibians is 

expected to be lower with the incorporation of these label changes. 

C. Interim Registration Review Decision 

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this 

Interim Registration Review Decision. Except for the EDSP and ESA components of this case, 

the Agency has made the following Interim Registration Review Decision: (1) guidelines 

860.1360 multi-residue methods and 860.1650 analytical reference standards are still data gaps; 

and (2) changes to the affected registrations and their labeling as described in this document are 

needed at this time (see Appendix B. Quizalofop Label Table). 

In this interim registration review decision, EPA is making no human health or 

environmental safety findings associated with the EDSP screening of quizalofop, nor is it making 

a complete endangered species finding. The Agency's final registration review decision for 

18 
quizalofop will be issued once an ESA Section 7 consultation with the Services has taken place, 

and an EDSP FFDCA section 408(p) determination has been made. 

V. NEXT STEPS AND TIMELINE 

A. Implementation of Mitigation Measures 

Registrants are required to submit proposed amended labels that include the agreed-upon 

changes to the Agency for approval within 60 days following issuance of the Interim 

Registration Review Decision. The changes are described in Appendices A and B. 

B. Final Registration Review Decision 

EPA will make a final registration review decision for quizalofop after ESA Section 7 

consultation with the Services has taken place and an EDSP FFDCA section 408(p) 

determination has been made. 

19 
References 

Bartholomew, Duane P., Kenneth G. Rohrbach, and Dale 0. Evans. "Pineapple Cultivation in 

Hawaii." College ofTropical Agriculture and Human Resources. University of Hawaii at 

Manoa, October 2002. Web. July 8, 20 14. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/f_n7.pdf 

Sipes, Brent. "Crop Profile for Pineapples in Hawaii" . National Information System for the 

Regional !PM Centers. United States Department of Agriculture, January 2000. Web. July 7, 

2014. http:l/www.ipmcenters.org/cropprofiles/docs/hipineapples.pdf 

20 
Appendix A: Summary of Mitigation for Quizalofop 

Registration Review Case#: 7215 PC Codes: 128711 (quizalofop-ethyl) and 128709 (quizalofop-p-ethyl) 

Chemical Type: herbicide Chemical Family: aryloxyphenoxy-propionate 

Mode of Action: inhibition of acetyl CoA carboxylase enzyme 

Affected Source of Route of Exposure Duration of Risk(s) of Concern Mitigation ~omment 

Population(s) Exposure Exposure 

./ Mammals ./ Water ./ Ingestion ./ Acute ./ Chronic ./ Restrict 

./ Monocots ./ Residues ./ Inhalation ./ Sub- toxicity application 

./ Freshwater at/on site ./ Dermal chronic ./ Reproductive methods 

fish of absorption ./ Chronic ./ Endocrine ./ Require spray 

./ Aquatic treatment ./ Transplacental disruption drift reduction 

phase ./ Dietary ./ Indirect 

amphibians ./ Air 

(aerosols 

during 

spraying, 

vapor) 

./ Soil 

EXAMPLES 

Affected Source of Route of Exposure Duration of Risk(s) of Concern Mitigation ~omment 

Population(s) Exposure Exposure 

Monocots Water, ~ystemic, direct hort term, Long-term Restrict application Risk to non-target 

Residues contact Long-term, exposure methods, plants reduced by 

at/on/near Require spray drift Implementing 

site of reduction droplet size 

reatment equirements and 

~oil emoval of aerial 

application for some 

uses 

Mammals Dietary, Dermal, Acute, Chronic toxicity Restrict application ~pray drift reduction 

~ir Ingestion, Chronic methods, measures reduce 

Inhalation, Require spray drift ~xposure to nonTransplacental reduction arget plants, which 

~re potential food 

~ources for 

mammals 

Freshwater fish, Water Dermal, ~cute, ~cute toxicity Restrict application ~pray drift reduction 

~quatic phase Ingestion ~hronic hron ic toxicity methods, measures and spot 

!amphibians Require spray drift ~reatment directions 

reduction, !On labels reduce off-

~pot treatment ~ite transport to 

label language jwaterways 

21 
Q-OPP-2007-1089 

ofop Label Table 

Summary of Labeling Changes for Quizalofop Uses 

Amended Labeling Language for Quizalofop Use Products 

End Use Products 

 paved areas, apply spot/small area treatments only. Do not treat > I 0% of the total paved area as spot/small area 

ment." 

ply by ground application equipment only. Do not apply by air." 

ply by ground application equipment only. Do not apply by air." 

. 

ply by ground application equipment only. Do not apply by air." 

ply by ground application equipment only. Do not apply by air." 

- -

Placement on Label 

Application 

Information 

Under "Nonagricultural Uses" 

Specific Crop Uses 

Under "For Use in 

Pineapple" 

Specific Crop Uses 

Under "For Use On 

Non-Food/Non-Feed 

Crops Grown Under Contract For Seed 

Production" i 

Specific Crop Uses 

Under "For Use In 

Eucalyptus 

Plantations" 

Specific Crop Uses 

Under "For 

Establishment of 

Hybrid Poplar 

Plantings" 

20 
Summary of Labeling Changes for Quizalofop Uses 

Description Amended Labeling Language for Quizalofop Use Products 

End Use Products 

Removal of aerial 

application to non-crop 

areas (such as fence "Apply by ground application equipment only. Do not apply by air." rows, roadsides, 

equipment storage areas, 

and etc) 

Medium/coarse or larger 

spray droplet size 

requirements for all "When applying by ground, use spray nozzles that will deliver medium/coarse or larger spray droplets as define

ground broadcast American Society of Agricultural and Biological Engineers (ASABE) standard ANSI/ASAE S572.1 (March 200

applications · 

Coarse or larger spray 

droplet size requirements 

for all aerial broadcast "When applying by air, use spray nozzles that will deliver coarse or larger spray droplets as defined in the Amer

applications Society of Agricultural and Biological Engineers (ASABE) standard ANSIIASAE S572.1 (March 2009)." 

Removal of grazing 

Restriction language 

Delete grazing restriction language.