2 

### TABLE OF CONTENTS

I. Preliminary Work Plan ........................................................................................................ 3
II. Fact Sheet ........................................................................................................................... 8
III. Ecological Risk Assessment ............................................................................................ 12
IV. Human Health Effects Scoping Document ................................................................... 46
V. Glossary of Terms and Abbreviations .............................................................................. 563 

### I. Preliminary Work Plan

Introduction:

The Food Quality Protection Act of 1996 mandate d a new program: registration review. All pesticides distributed and sold in the United St ates must be registered by the EPA, based on scientific data showing that th ey will not cause unreasonable risks to human health, workers or
the environment when used as directed on th e product label. The ne w registration review program is intended to ensure that as the abil ity to assess risk evol ves and as policies and practices change, all registered pesticides co ntinue to meet the st atutory standard of no unreasonable adverse effects. Changes in science, public policy, and pestic ide use practices will occur over time. Through the new registrati on review program, the Agency periodically reevaluates pesticides make sure that as the ch ange occurs, products in the marketplace can be used safely. Information on this prog ram is provided at the following website: http://www.epa.gov/oppsrr d1/registration_review/

.

The Agency has begun to implement the new Regi stration Review program and will review each registered pesticide every 15 years to determine wh ether it continues to m eet the FIFRA standard for registration. The public phase of registration review begins wh en the initial docket is opened for each case. The docket is the Agency’s opportun ity to state what is knows about the pesticide and what additional risk analyses and data or ot her information it believes are needed to make a registration review decision. Afte r reviewing and responding to co mments and data received in the docket during this in itial comment period, the Agency will develop and commit to a final work plan and schedule for the registration review of quizalofop.

Quizalofop is a selective post-emer gence herbicide used on a number of food and feed crops. It was registered for use in the late 1980’s. Qui zalofop-ethyl is a 50/50 race mic mixture of R- and S-enantiomers. Quizalofop-p-ethyl is the purified R-enantiomer and the pesticidally active
isomer.

Anticipated Risk Assessment and Data Needs:

The Agency anticipates conducting comprehe nsive human health and ecological risk assessments, including an endangered species assessment, for all uses of quizalofop.

Ecological Risk:

• New ecological risk assessments for all re gistered uses were conducted in October 2005. However, the Agency has not conducted a risk assessment that supports a complete endangered species determinat ion for quizalofop-ethyl or quizalofop-pethyl and a complete assessment will be conducted for registration review. Please refer to Section III, Ecological Risk Asse ssment Problem Formulation, for a detailed discussion of the anticipated risk assessment needs.4 • There are two chronic avian studies, wh ich have been submitted. If upon further review, these studies do not pr ovide useful information on the reproductive effect of quizalofop in birds, new studies will be required.

• The Agency anticipates needing the followi ng data in order to conduct a complete ecological risk assessment, including an e ndangered species assessment, for all uses:

o (GLN 850.4225) Seedling emergence (Tier 2) for quizalofop-p-ethyl.

o (GLN 850.4250 ) Vegetative vigor (T ier 2) for quizalofop-p-ethyl.

o (GLN 850.1350) Chronic early life-cycle to xicity studies for estuarine marine invertebrates for quizalofop-p-ethyl.

• The planned ecological risk assessment will allow the Agency to determine whether quizalofop use has "no effect" or "may a ffect" federally listed threatened or endangered species (listed species) or thei r designated critical habitat. If the assessment indicates that quizalofop “may af fect" a listed species or its designated critical habitat, the assessment will be refined to determine whether use of quizalofop is “likely to adversely affect” the species or critical habitat or "not likely to adversely affect" the species or critical habitat. When an assessmen t concludes that a pesticide's use "may affect" a listed species or its de signated critical habitat, the Agency will
consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Service (Services), as appropriate.

Human Health Risk:

• The current dietary risk assessment for qui zalofop-ethyl was c onducted according to Agency policy and results in no risks of c oncern. Because the toxi cological profile of quizalofop-ethyl and quizalof op-p-ethyl are sufficiently similar, the Agency has determined the currently available toxicity data on quizalofop-eth yl are adequate to support risk assessments reflecting uses of both quizalofop-ethyl and quizalofop-pethyl. Although occupational risk assessments have not been completed for all uses, no dermal or inhalation endpoints have been selected because quizalofop-p-ethyl and quizalofop-ethyl do not appear to be toxic via dermal and inhalation routes of exposure. Based on existing risk assessmen ts, occupational exposure risk appear to well below the Agency’s level of concern (LOC). Therefore, additional assessments
are not needed.

• The Agency anticipates no revisions to the human health risk assessments. No new human health data are required.

Timeline:

EPA has created the following estimated timeline for the completion of the quizalofop registration review.5 Activities Estimated Month/Year

Phase 1: Opening the Docket Open Public Comment Period for Quizalofop Docket 2007– Dec.

Close Public Comment Period 2008– Mar. Phase 2: Case Development Final Work Plan (FWP) 2008– May-July

Issue DCI 2009– Mar.-May

Data Submission 2011– Mar.-May Preliminary Risk Assessment & Public Comment 2012– Sep.-Nov.

Close Public Comment Period 2012– Nov.-Jan. Phase 3: Registration Review Decision Open Public Comment Period for Proposed Reg. Review Decision 2013– Feb.-Apr.

Close Public Comment Period 2013– Apr.-Jun. Final Decision and Begin Post-Decision Follow-up 2013

Total 6 years

Guidance for Commenters

The public is invited to comme nt on EPA’s preliminary regist ration review work plan and rationale. The Agency will carefully consid er all comments as well as any additional information or data provided prior to issuing a final work plan for quizalofop.

Through the registration review process, the Ag ency intends to solicit information on trade irritants and, to the extent feas ible, take steps toward facilitating irritant resolution. Growers and other stakeholders are asked to comment on any tr ade irritant issues resulting from lack of Maximum Residue Limits (MRLs) or disparitie s between U.S. tolerances and MRLs in key export markets, providing as much specificity as possible regarding the nature of the concern. There are 44 U.S. tolerances for quizalofop-p- ethyl and quizalofop-ethyl , but not all of these
tolerances have been harmonized with MRLs at this time. Tolerances on animal commodities
have been harmonized with Canada. Other tole rances have not been harmonized, but allowable
residue levels are similar. Please refer to Sec tion IV of this document, Human Health Effects Scoping Document, for a detailed comparison of MRLs.

Quizalofop is not identified as a cause of impa irment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on information provided at http://oaspub.epa.gov/tmdl/waters_list.impairments?p_impid=3 . The Agency invites submission of water quality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of the “OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in O PP’s Registration Review Risk Assessment and Management Process” (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1- sop.pdf ), in order to ensure they can be used qua ntitatively or qualitatively in pesticide risk

assessments.6 EPA seeks to achieve environmenta l justice, the fair tr eatment and meaningful involvement of all people, regardless of race, color, national origi n, or income, in the deve lopment, implementation, and enforcement of environmental laws, regulations, and policies. To help address potential environmental justice issues, the Agency seeks information on any groups or segments of the population who, as a result of thei r location, cultural practices, or other factors, may have atypical or unusually high exposure to quizalofop , compared to the general population. Please comment if you are aware of any sub-populations that may have atyp ical or unusually high exposure compared to th e general population.

Stakeholders are also specifically asked to prov ide information and data that will assist the Agency in refining the ecological risk asse ssment, including any species-specific effects
determinations.

The Agency is interested in receiving the following information:

1. confirmation on the following label information

a. sites of application
b. formulations

c. application methods and equipment
d. maximum application rates in units related to mass per unit area of treatment zone

e. frequency of application, applicati on intervals, and maximum number of applications per season
f. geographic limitations on use

2. use or potential use distributi on (e.g., acreage and geographica l distribution of relevant crops)
3. use history

4. median and 90 th percentile reported use rates (lbs ai/acre) from usage data – national, state, and county
5. application timing (date of first application and application interval s) by crop – national, state, and county

6. sub-county crop location data

7. usage/use information for non-agricultural uses (e.g., forestry, reside ntial, rights-of-way)

8. directly acquired county-level usage da ta (not derived from state level data)

a. maximum reported use rate (lbs a i/acre) from usage data – county
b. percent crop treated – county

c. median and 90 th percentile number of applications – county
d. total pounds per year – county

e. the year the pesticide was last us ed in the county/sub-county area
f. the years in which the pesticide was applied in the county/sub-county area

9. typical interval (days)

10. state or local use restrictions

11. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and mammalian mortalities) not alr eady reported to the Agency

12. monitoring data7 Next Steps:

After the comment period closes, the Agency w ill review any comments received, and then issue a Final Work Plan for this pesticide.8 

### II. Fact Sheet

The Quizalofop Registration Review Case (#7215) includes two active ingredients:

1. Quizalofop-p-ethyl
2. Quizalofop-ethyl

Background Information :

• Quizalofop-p-ethyl is part of Registration Review case number: 7215

• Quizalofop-p-ethyl PC Code: 128709 CAS#: 100646-51-3

• Technical registrants:

o E.I. Du Pont De Nemours Co., Inc. (Company No. 352)

o Nissan Chemical Industries Ltd. (Company No. 33906)

• First approved for use in a registered product in 1990.

• Not subject to reregistration (no Reregi stration Eligibility Decision [RED]).

• There are six FIFRA section 3 registrations and four FIFRA secti on 24(c) special local need registrations

• Quizalofop-ethyl is part of Registrati on Review case number: 7215

• Quizalofop-ethyl PC Code: 128711 CAS#: 76578-14-8

• Technical registrant:

o E.I. Du Pont De Nemours and Co., Inc. (Company No. 352)

• First approved for use in a registered product in 1988, however all end use product registrations have been cancelled prior to 1996.

• No current active end-use products. One active technical registration.

• Quizalofop-ethyl is a 50/50 racemic mixture of R- and S-enantiomers. Quizalofop-pethyl is the purified R-enantiomer and the pesticidally active isomer. Because the toxicological profile of the 50/50 racemi c mixture (quizalofop-ethyl) and the Renantiomer (quizalofop-p-ethyl) are sufficiently similar, the Agency has determined that the currently available toxicity data on qui zalofop-ethyl are ade quate to support risk assessments reflecting uses of both quizal ofop-ethyl and quizalo fop-p-ethyl (the Renantiomer).

• Special Review and Reregist ration Division Chemical Revi ew Manager (CRM): Rusty

Wasem: wasem.russell@epa.gov

.

• Registration Division Product Manager (PM): James Tompkins: tompkins.james@epa.gov

.9 Use & Usage Information:

(For additional details, please refer to th e BEAD Appendix A document in the quizalofop docket.)

• Quizalofop is a selective postemergence herbicide that is used to control annual and perennial grasses, excluding sedges and broadleaf weeds.

• Quizalofop is used on food, feed, seed, and for other non-food/non-feed uses. Food, feed, and seed uses include the following: grains , legumes, cotton, garlic, mint, soybean, sugar beets, sunflower, pineapple, and Chines e cabbage. Non-food/non-feed uses include: cottonwood and poplar plantations, and uncul tivated areas such as fencerows and
roadsides.

• There are no residential uses.

• Application methods:

o ground (broadcast, band, or s oot spray), or aerial

o post-emergence of weeds

• Greatest poundage of quizalofop is used on soybeans.

• Approximately 30% of mint and 10% of ca nola/rapeseed, dry bean s/peas, and garlic crops are treated with quizalofop(according to SLUA).

Recent Actions:

• In October 2005, Drinking water exposu re for quizalofop-p-ethyl (TARGATM) on proposed and registered uses were completed.

• In October 2005, Environmental Fate and Eff ects Division (EFED) risk assessments were completed.

• In August 2006, Health Effect s Division (HED) human health risk assessments were completed.

• In November 2006, Section 3 new use registration request for quizalofop-p-ethyl (TARGATM) on sunflowers, flax, wheat and barley were approved.

Ecological Risk Assessment Status:

The following ecological outcomes are antici pated based on the limited data and risk assessments currently available. Please refer to Section III, Ecological Risk Assessment Problem Formulation, for a detailed discussion of the an ticipated ecological risk assessment needs. A summary follows:

• Risks are unlikely to exceed the Agency’s LOC for listed and non-listed species for: acute risks to aquatic invertebrates, aquati c plants, birds, fish, mammals, terrestrial
invertebrates.10 • Risks are unlikely to exceed the Agency’s LOC for listed and non-listed species for: chronic risks to aquatic plants, birds, fish, and terrestrial invertebrates.

• Risks are likely to exceed the Agency’s LOC for liste d and non-listed spec ies for chronic
risks to mammals.

• Acute and chronic risks to non- target terrestrial plants ha ve not been assessed, but are expected to exceed the Agency’s LOC.

• Uncertainty exists for chronic risks to aqua tic invertebrates, since the Agency has no chronic toxicity data for ri sk assessment. These data are required for estuarine
invertebrates since estuarine animals seem to be more sensitive than freshwater animals in acute toxicity tests.

Human Health Risk Assessment Status:

Please refer to Section IV, Human Health Effect s Scoping Document, for a detailed discussion of the anticipated risk assessment needs for human health. A summary follows:

Dietary (Food and Water):

• Acute dietary risk assessments for quizalof op-p-ethyl and quizalofop-ethyl were deemed unnecessary because no toxic endpoint attrib utable to a single oral dose has been identified. Therefore, no acute di etary assessment has been conducted.

• Chronic dietary risk assessments for qui zalofop-p-ethyl and quizalofop-ethyl are
conservative and unrefined with risks belo w the Agency’s LOC because the dietary analysis was based on to lerance level residues.

• There are no dietary risks for quizalofop-p- ethyl and quizalofop-ethyl that exceed the Agency’s LOC.
Residential:

• There are no residential uses of qui zalofop-p-ethyl and quizalofop-ethyl. Occupational :

• An occupational assessment was conducted fo r quizalofop-p-ethyl for the proposed uses on barley, flax, sunflower and wheat in 2006.

• Risk estimates based on inhalation exposures of pesticides handlers and applicators for quizalofop-ethyl for barley, flax, sunflower, wheat, cotton, pineapple, and non-crop areas are below the Agency’s LOC.

• Occupational assessments are not necessary fo r quizalofop-ethyl beca use there is only a technical registration.

Tolerances:

• The following is a summary of tolerances for quizalofop-p-ethyl according to CFR §180.441.

o quizalofop-ethyl

 36 tolerances

o quizalofop-p-ethyl

 7 tolerances

 1 tolerance (regional)11 Data Call-In Status:

• A DCI has not been issued for qui zalofop-p-ethyl or quizalofop-ethyl.

• DCI(s) will be issued for quizalofop dur ing the registration review process.

Labels :

A list of registration numbers may be found in the docket and the labels for quizalofop-p-ethyl and quizalofop-ethyl can then be obtained from the Pesticid e Product Label System (PPLS)
website: http://oaspub.epa.gov/pestlabl/ppls.home

.13 EXECUTIVE SUMMARY

Quizalofop-ethyl (including its R-enantiomer, quizal ofop-p-ethyl) is a systemic herbicide that is rapidly absorbed by treated foliage and translocated to the roots and other growing points of the plant. Affected plant tissues become necrotic/chl orotic and die leaving treated plants stunted and non-competitive. It controls annua l and perennial grasses. It ca n be applied using ground boom equipment, fixed wing aircraft as broadcast and banded applications, airb last and soil injection treatment applications. It is normally applied at low rates.

Currently, only products contai ning quizalofop-p-ethyl are regi stered. There are no active registered products containing qui zalofop-ethyl. Quizalofop-ethyl is a 50/50 racemic mixture of R- and S-enantiomers. Quizalofop-p-ethyl is the purified R-enantiomer. The pesticidally active isomer is the R-enantiomer (quizalofop-p-ethyl).

Quizalofop-ethyl and quizalofop-p-et hyl (the R-enantiomer) were firs t registered in 1988. As a result, they were not subject to review under th e re-registration process recently completed under FIFRA and FQPA as of August 3, 2006 for chemi cals registered prior to 1984. Consequently, neither a Re-registration Eligibility Decision (R ED) nor a Tolerance Re-registration Eligibility Decision (TRED) is available for the Registration Review process of these chemicals.

The most recent EFED risk assessments were completed in October 28, 2005, which reflect current registrations and uses of quizalofop-ethyl and quizalofop-p- ethyl. Based on the results of those assessments, the followi ng risk concerns were noted:

- Chronic risks to listed and non-listed mammals

- Anticipated risks to listed a nd non-listed terrestrial plants

- Potential chronic risks to liste d and non-listed estuarine/marine invertebrates. Since the toxicological profile of the 50/50 racemi c mixture (quizalofop-ethyl) and the Renantiomer (quizalofop-p-ethyl) are not complete, uncertainty exists for this assessment.

EFED anticipates revisions to the risk asse ssments based on new application scenarios and additional toxicity data request ed. A new drinking water asse ssment may also be needed to address any new uses and/or ap plication scenarios and to comp ly with new EFED guidelines.14 Table 1 summarizes quizalofop-p-ethyl and quizalofop-ethyl submitted studies and studies that are requested to complete the toxicological profile.



### Table 1 List of studies submitted and studies requested

Studies submitted quizalofop-p-eth y l Studies submitted ** quizalofop-eth y l Studies requested quizalofop-p-ethyl Seedling emergence (unacceptable) Avian acute (mallard duck and bobwhite quail) Seedling emergence based on TEP tier II

Vegetative vigor (unacceptable) Av ian dietary (mallard duck and bobwhite quail) Vegetative vigor based on TEP tier II

Chronic bird (mallard duck and bobwhite quail) Acute rat Chronic estuarin e marine invertebrate most sensitive species (mysid).
No chronic freshwater or estuarine
marine invertebrate studies were
submitted therefore a chronic estuarine marine invertebrate study is requested to quantify risks. This data will also be used
to estimate chronic values for freshwater
invertebrates. non- vascular aquatic plant study
tier l green algae ( Selanastrum capricornutum)* Acute freshwater fish (Rainbow trout and Bluegill)

non- vascular aquatic plant study
tier l blue green algae (Anabaena flosaquae ) Acute freshwater aquatic invertebrate (daphnid)

non- vascular aquatic plant study
tier l
estuarine marine diatom ( Skeletonema costatum ) Acute estuarine marine fish (sheepshead minnow)

non- vascular aquatic plant study
tier l freshwater diatom ( Navicula pelliculosa ) Acute estuarine marine aquatic invertebrate (mysid)

vascular aquatic plant study tier 1 Duckweed ( lemna gibba)* Chronic freshwater fish (fathead minnow) Nontarget insects (honeybee)

* Non vascular plant NOAEC values were not determined for quizalofop-p-ethyl. In the absence of those data, EFED based its risk estimation for non vascular plants on data from the NOAEC from the analog fenoxaprop-p-ethyl (27 ppb). It is understood that fenoxaprop-p-ethyl is more toxic to non vascularplants than quizalofop-p-ethyl (EC50 of 1770 ppb for quizalofop-p-ethyl vs 430 ppb for fenoxaprop -pethyl for Selanastrum capriconutum, the most sensitive sp ecies tested for both chemicals), and using data from fenoxaprop-p-ethyl may overestimate risk for quizalofop-p-ethyl. However, a chronic RQ of only 0.23 was observed when comparing the fenoxaprop-p-ethyl NOAEC of 27 ppb to the exposure data of quizalofop-p-ethyl at the highest application rate of 0.4125 lb ai/A15 Therefore, although the above estimated values may no t be complete substitutes for missing effects data, EFED is confident that listed species LOCs would not be triggered even if assessed with definitive NOAEC values. Thus, additional tier II toxicity data will not be requested at this time for non-vascular plants. Estimated EECs for highest application rate of 0. 4125 lb ai/A per season= 0.4125 lb ai/A/ 0.165lb ai/A=2.5 2.5x EEC 2.57 ppb (table#6) =6.425 ppb EECs for highest application rate. RQ=6.425 ppb/27 ppb NOAEC from fenoxaprop-p-ethyl =RQ 0.23
The NOAEC for lemna gibba however will be equal to the highest nominal concentration of 82.8 ppb.

** Additional studies for terrestrial and aquatic plants, chronic reproductive bird and chronic aquatic fish and invertebrates may be requested if quizalofop-et hyl is registered as an active labeled use.

PROBLEM FORMULATION

Problem formulation is used to es tablish the direction a nd scope of an ecological risk assessment. According to the Guidelines for Ecological Risk Assessment (USEPA, 1998), problem formulation consists of defining the problem and purpose for the assessment, and developing a plan for analyzing and characterizing risk. The critical components of the problem formulation are selection of the assessment endpoints, form ulation of risk hypotheses and the conceptual model, and development of an analysis plan. The analysis plan and supporting rationale are aimed at determining whether the uses of quizalofop-p-ethyl and quizalofop-ethyl on NonFood/Non-feed uses (alfalfa, beet s, carrot ( including tops), swi ss chard, grasses grown for seed, cottonwood/poplar plantations, non-a gricultural uncultivated areas /soils, onion, ornamental and or shade trees, radish spinach and for Food a nd Feed uses ( agricultura l fallow/idleland, barley, succulent and dried beans, snap beans, chinese cabbage, eucalypt us, canola, rape, cotton, crambe, flax, garlic, lentils, mint, peppermint and sp earmint, dried and succulent peas, pineapple, soybeans, sugarbeets including tops, sunflower a nd wheat) could result in exposures that cause unreasonable adverse effects (risk) to non-target organisms incl uding those federally listed as threatened or endangered (hereafter referred to as “listed”).

1. INTEGRATION OF AVAILABLE INFORMATION

The risk assessments available in the docket, and which serve as the basis for this problem formulation, include the following:

• October 28, 2005, Section 3 New use regi stration request for quizalofop-p-ethyl (TARGA TM ) on sunflowers, flax, wheat and barley (DP 310868)

• October 28, 2005, Drinking water expos ure for quizalofop-p-ethyl (TARGA TM ) on proposed and registered uses (DP 310868)

Risks, as identified in these assessments, are:16 For mammals: Chronic risk to mammals, based on aerial and ground spray applications, occurred for the following crops:(1) sunflowers with a maxi mum seasonal rate of 0.12 lb ai /acre; (2) flax with a maximum seasonal rate of 0.165 lb ai /acre; and 

### (3) wheat and barley with a maximum
seasonal rate of 0.08 lb ai acre. Chronic RQs ranged from 1.14 to 3.54.

In addition, exceedences are anticipated for chronic risk to estuarine marine invertebrates with higher application rates. Terrestrial plants can not be assessed due to la ck of acceptable data, however exceedences are anticipat ed for all modeled scenarios due to the chemical properties and mode of action of quizalofop-p-ethyl.

There are no reported incidents for 128711. Th ere is only one incident for 128709 ref.# 1016677- 001 which involved damage to some garden plants after they were exposed to spray drift of quizalofop-p-ethyl (Assure II) plus fomesafen s odium (Flexstar). Because the plants were exposed to two herbicides, it is uncertain which one or both cau sed the observed plant damage.

1. DATA GAPS AND ANTICIPATED DATA NEED

As mentioned above, the toxicol ogical profile of the 50/50 racemi c mixture (quizalofop-ethyl) and the R-enantiomer (quizalofop-p-ethyl) are not co mplete and the currently available toxicity data on quizalofop-ethyl are not adequate to support risk asse ssments reflecting uses of both quizalofop-ethyl and quizalofop-p-ethyl (the R-en antiomer). EFED will re quest additional data to complete the toxicological profile for quizalofop-ethyl and quizal ofop-p-ethyl (the Renantiomer).

Below is the preliminary identification of data gaps for the fate and ecological assessment:

Seedling emergence and vegetative vigor tests The terrestrial seedling emergence and vegetative vigor tests for plants exposed to quizal ofop-p-ethyl that were submitted to the Agency in 1994 were classified as unacceptable. The Ag ency guidelines require that terrestrial plant toxicity testing for herbicides be performed usi ng the typical end-use pro duct (TEP). In addition, the above studies lack negative controls and in sufficient information de monstrating that the
concentration of acetone used in the study does not inhibit plant growth.
Decision: Seedling emergence and vegetative vigor studies based on TEP are requested for terrestrial seedling emergence and vegetative vigor tests for quizalof op-p-ethyl. Seedling Emergence (GLN 123-1a/850.4225) Vege tative Vigor (GLN 123-1b/850.4250)

Chronic estuarine/marine fish toxicity tests - The No Observable Adverse Effect Concentration (NOAEC) value of 33 ppb for estuar ine/marine fish was estimated by applying the acute-to-chronic ratio (ACR) ) from freshwater to xicity tests to the estuarine/marine acute toxicity values. In addition, no LOC exceedences occurred for chronic estuarine marine fish with RQs <0.01 for the 0.165 lb ai /A scenario. LOC exceedences are not anticipated for chronic estuarine marine fish with the higher a pplication rate of 0.4125 lb ai/A per season.
Decision: Chronic estuarine/mari ne fish toxicity tests studies are not requested17 Estuarine/marine invertebrate Early Life-Cycle toxicity data

– No early life stage estuarine/marine invertebrate studies were submitted to the Agency. Estuarine marine invertebrates are the most sensitive aquatic organisms (mysid) exposed to quizalofop-ethyl. Since exceedences are expected from quizal ofop-p ethyl and quizalof op-ethyl from many application scenarios, the early life-cycle estuarine marine inve rtebrate study for quizalofop-pethyl with mysid shrimp (most sensitive species tested) will be requested since no active labels exist for quizalofop-ethyl. However, if active labels occur for quizalofop-ethyl then additional
studies for estuarine marine inve rtebrates would be requested.
Decision: Chronic early life-cycle estuarine/ marine invertebrate toxicity tests studies with mysid (most sensitive species) conducted on quizalofop-p-ethyl are requested (GLN 72- 4b/850.1350).

Freshwater invertebrates Early Life-Stage toxicity test - No early life-stage or full life-cycle
chronic invertebrate studies were submitted for fr eshwater or estuarine marine invertebrates. However, based on ACRs derived from acute and chronic freshwater fish data, no exceedences
would occur for chronic freshwater inve rtebrates exposed to quizalofop-ethyl.
Decision: An Early life-stage chronic freshwater invertebrate toxicity test for quizalofop-pethyl is not requested. Estimated values derived from ACRs will be sufficient.

Tier II study for non-vascular plant based on ( Selanastrum capricornutum) NOAECs were not determined for non-vascular pl ants exposed to quizalofop-p-ethyl to address listed species concerns and no studies were subm itted for quizalofop-ethyl. A Tier II study which
defines a NOAEC value would be be neficial in the definitive determination of risks to nonvascular plants. Risks to listed species are curre ntly assessed using data from fenoxaprop-p-ethyl, a structural analog of quizalof op-p-ethyl. No LOCs exceedances were noted at the highest application rate of 0.4125 lb ai/A per season based on estimated EECs.
Decision: A Tier II study for non-vascular plants based on Selanastrum capricornutum for quizalofop-p-ethyl is not requested at this time. Data may be required for any future use with application rates higher th an 0.4125 lb ai/A per season.

Environmental Fate Data and Sediment Toxici ty Data for the degradate quizalofop acid: Quizalofop-p-ethyl is anticipated to degrade quickly in soil to the major degradate, quizalofop acid. Previous assessments assume that quizalofop acid is the main species present in water, and that it is of equivalent toxic ity as the parent. Furthermore, for exposure, this degradate was presumed to be stable via hydrolysis and phot olysis, and in anaerobic environment (soil and water). With those assumptions, only chronic ri sks to listed and non- listed freshwater and estuarine marine invertebrates were anticipated, however not fully characterized due to lack of toxicity data.
Decision: Based on the current database for quizalof op-p-ethyl, environmental fate data for quizalofop acid are not required. However, if furt her assessment indicates toxicity and risks to aquatic organisms, those data may be reque sted for a refined ri sk characterization.18 2. PESTICIDE TYPE, CLASS, AND MODE OF ACTION

Quizalofop-p-ethyl is a selective, post-emergence organic ph enoxy herbicide that belongs to a subclass of phenoxy compounds known as Aryl oxyphenoxys (fops). Quizalofop-p-ethyl is absorbed by the treated foliage and translocated to the roots and other growing points of the plant. Herbicides categorized as arloxyphenoxys have several modes of action which are as follows: (1) 

### In terrestrial and aquatic vascular and nonvasc ular plants--- inhibition of acetyl CoA carboxylase (ACCase), a key enzyme in lipid biosynthesis; (2) 

### In terrestrial and aquatic vascular and non-vascular plants-inhibition of cell mitosi s or immediate termin ation of mitosis once exposure has been known to occur; (3) 

### In terrestrial and aquatic va scular and non-vascular plants- inhibition of Acetyl-CoA carboxylase and the fatty acid synthesis pathway causes an inhibition of thylakoid membrane formation, chloroplast formation and multiplication, and finally a halt of cell membrane formation and cell division.

4. STRESSOR SOURCE AN D DISTRIBUTION

The sources of the stressor considered are quizalofop -p-ethyl (PC Code 128709), quizalofopethyl (PC Code 128711), and quizalofop acid, the major degradate of concern.

Quizalofop-p-ethyl is stable to hydrolysis at pH’s 

### 5 and 7. Hydrolysis occurs at pH 

### 9 with a half life of 2 days. Quizalofop-p-ethyl is stable to pho tolysis in water and soil. Acceptable aerobic soil metabolism study show that quizalofop-p-ethy l degrades with a ha lf-life of 1 day to quizalofop acid and phenolic compounds. Quizalofop aci d is considered to be the major exposure concern. Based on available fate studies, the acid is less persistent than the parent under aerobic
conditions but more mobile than the parent compound. Its soil me tabolism half lives in aerobic environment range from 4 to 8 weeks, dependi ng on soil types. As for mobility, the mean adsorption K
oc of quizalofop acid is 476 (which is classifi ed as moderately mobile), whereas the mean adsorption K
oc value of quizalofop-p-ethyl is 1816 (which is classified as slightly mobile). No additional environmental fate data are available for quizalofop acid.

As mentioned above, quizalofop-p-ethyl degrades quickly to form quizalofop acid, the major concern of aquatic exposure would be from this de gradate. This degradate was also detected in
livestock tissues and is included in the toleran ce expression and the HED risk assessment. Its toxicity level was determined by HED to be equivale nt or less than that of the parent. As for exposure, in the absence of fate data, the solubil ity was assumed to be equivalent to those of the parent and all abiotic degrad ation (hydrolysis and photolys is) and anaerobic metabolism processes, non existing.

Currently, quizalofop-p-ethyl is applied as a ground spray, aerial , air blast and soil injection applications. Trade and other names of produc ts containing quizalof op-p-ethyl include: (1) Assure II; (2) Matador; (3) Dupont Assure II ;(4) MON 78746.19 Quizalofop-p-ethyl is registered for several food crops and it is us ed to control the growth of perennial and annual grasses, weeds and vines. During the period of 2000-2006, approximate annual usage for quizalofop-p-et hyl and quizalofop-ethyl was 89,500 pounds. The usage data for quizalofop-p-ethyl and quizalofop- ethyl does not distinguish be tween the two chemicals. Quizalofop-ethyl did not have an active product registration during the period of data collection. The greatest poundage of quizalofop is used on soybeans (SLUA from BEAD). Quizalofop accounts for 30% of mint treated, 10% of canola/rape seed with a maximum of 20% treated, followed by dry beans/peas and garlic averaging 10% of the crop treated (SLUA from BEAD). While these data provide some insight into the historic use of quizalofop-p-ethyl, herbicide use changes with th e varying resistance of pest plants; predicting total use prospectively is difficult since it ma y be based on the susceptibility of a particular pest plants to a specific herbicide.

Terrestrial exposure is based on direct spray application on food items including short grass, seeds, and broadleaf plants and insects resulting from applications of quizalofop-p-ethyl at the maximum label rates. Exposure to aquatic organi sms is the result of runoff and spray drift from labeled applications, and is functionally the amount of compound in the wate r that would directly contact organisms. The magnitude of exposure estimates is largely de pendent on the biology of the receptor ( e.g. , food consumption rate), the use patterns , and environmental fate and transport characteristics of the pesticide.

5. OVERVIEW OF PESTICIDE USAGE

Quizalofop-p-ethyl is a herbicide that is used to contro l weeds in Non-Food/Non-feed uses (alfalfa, beets, carrot ( including tops), swiss chard, grasses grown for seed, cottonwood/poplar plantations, non-agricultural uncul tivated areas/soils, onion, orna mental and or shade trees, radish spinach and for Food and Feed uses ( ag ricultural fallow/idle land , barley, succulent and dried beans, chinese cabbage, canola, eucalyptus, rape, cotton, crambe, flax, garlic, lentils, mint, peppermint and spearmint, dried and succulent peas , pineapple, soybeans, sugarbeets including tops, sunflower, and wheat). Quizalofop-p-ethyl is formulated as a wettable powder, soluble concentrate and liquid, and can be applied as various spray treatments such as; ground, soil injection, aerial and air blast.

The currently approved quizalofop-p- ethyl application ra tes for agricultural uses range from 0.0650 lb ai/acre (cotton) to 0.2063 lb ai/acre (pineapple) for a single application (BEAD 2007)
with a seasonal maximum label rate of 0.4125 lb ai/acre (pineapple). For non-agricultural uses the maximum rate per applicati on is 0.2063 lb ai/acre (o rnamental and/or sh ade trees) with a
seasonal maximum label rate of 0.4125 lb ai/acr e (ornamental and/or shade trees) (BEAD 2007).

6. ENVIRONMENTAL FATE SUMMARY

Quizalofop-p-ethyl has a relative low water so lubility of 0.4 mg/L. 

### In organic solvents20 such as acetone, hexane, and ethanol, quizalofop-p-et hyl is very soluble. It has a vapor pressure of 3 x mm Hg (@ 20'~) and a calculated Henry's law constant of 3.7 x atm-m3/mole. The hydrolysis rate is pH variable ; with the half-life of 600 days at pH 5, 30 days at pH 7, and 2 days at pH 9. Supplemental studies also show that quizalofop-p-ethyl is moderately mobile

with 

### K ad 

### s of 1.5-1.9 in sandy loam soil, and im mobile in silt loam soil with 

### K ad 

### s of 16-20. Existing data from the Environmental Fate and Effects Division (EFED) files show conflicting results between laboratory studies and field studies. The acceptable laboratory aerobic soil metabolism study shows that quizalof op-p-ethyl degrades microbially with a half-life of 1 day in sandy loam and silt loam soils. However, quizalofop- p-ethyl was persistent in the field with halflives of 145 and 364 days for studies conducted in 

### IL and CA, respectively. The inconsistency in results between the laboratory and the field st udies may be due to differences of pHs and microbial populations in the soil media use d, and differences between the purposes of each study.

The acceptable fish accumulation study indicated th at quizalofop-p-ethyl did not bioaccumulate with 28-day values of 1X and 4X for e xposure concentrations of 0.004 and 0.04 mg/L, respectively.

As for the acid degradate, in the absence of data, previous assessment assumes that it is stable to both biotic and abiotic degradation and it ha s equivalent solubility to the parent.

7. ECOLOGICAL EFFECTS SUMMARY

Table 2 provides taxonomic groups and test species us ed to indicate the potential for ecological effects in this screening-level risk assessmen t. Within each of th ese very broad taxonomic groups, an acute and/or chroni c endpoint is selected from the available test data.

Table 2. Taxonomic Groups and Most Sensitive Test Species Evaluated for Ecological Effects of quizalo fop-ethyl and quizalofop-p-ethyl*

Taxonomic group Example(s) of representative species Endpoint Used

Birds a Bobwhite quail ( Colinus virginianus ) Mallard duck ( Anas platyrhynchos ) Acute LD 50 Acute LC 50 Chronic, NOAEC*

Mammals Laboratory rat ( Rattus norvegicus ) Acute LD 50 NOAEC

Terrestrial insects Honeybees ( Apis mellifera ) Acute Oral LD 50 N/A
Acute Contact LD 50

Freshwater fish b Rainbow trout ( Oncorhynchus mykiss ) Bluegill sunfish ( Lepomis macrochirus )

Fathead minnow (Pimephales promelas) Acute LC 50 Acute LC 50

Chronic NOAEC21 Table 2. Taxonomic Groups and Most Sensitive Test Species Evaluated for Ecological Effects of quizalo fop-ethyl and quizalofop-p-ethyl*

Taxonomic group Example(s) of representative species Endpoint Used

Freshwater invertebrates Water flea ( Daphnia magna ) Acute EC 50

NOAEC N/A no study
submitted. Estimated values
will be used in future

assessments.

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus) Acute LC 50

Estuarine/marine invert ebrates Mysid shrimp ( Mysidopsis bahia )

Eastern oyster ( Crassostrea virginica ) Acute EC 50 NOAEC N/A no studies
submitted

Terrestrial plants* Monocots – N/A
Dicots – N/A Seedling Emergence Vegetative Vigor EC 25 N/A unacceptable studies
submitted.

Vascular aquatic plants* Duckweed (Lemna gibba) Tier1 Acute EC 50 NOAEC N/A in previous
risk assessments. Future
risk assessment will use highest concentration value

as NOAEC.

Non-vascular aquatic plants* Green algae ( Selanastrum capricornutum )
Tier I Acute EC 50 NOAEC or EC 05 N/A Since a maximum growth
inhibition observed was 19% from the tier I study a
NOAEC value from a Tier II test would quantify risks. However, EFED will quantify risks to listed species through estimated values and analog data.

a Birds are used as surrogates for terrestrial phase amphibians and re ptiles (US EPA, 2004).

b Freshwater fish are used as surrogates fo r aquatic phase amphibians (US EPA, 2004). *Studies were conducted on quizal ofop-p-ethyl only. Studies not identified by an asterisk were conducted on quizalofop-ethyl.22 8. ECOSYSTEMS AT RISK

The ecosystems that could be potentially at risk due to agricultural use of quizalofop-p-ethyl include terrestrial and aquatic (l akes, ponds, streams) habitats in proximity to quizalofop-p-ethyl use areas. These habitats may be at risk from drift and/or runoff of quizalofop-p-ethyl from use areas. The estuarine/marine ecosystems are likely at less risk since they are typically further from agricultural areas and are ch aracterized by large volumes of water. However, in some areas adjacent to estuarine/marine environments wher e agriculture dominates the landscape, risks to estuarine/marine ecosystems cannot be excluded.

Organisms of concern include birds, mammals, reptiles, fish, and terrestrial and aquatic invertebrates, plants, and amphibians. The assessment endpoints are intended to reflect population sustainability and community structure within ecosystems and hence relate back to ecosystems at risk. If risks are expected fo r given species/taxa base d on the screening-level assessment, then risks might be expected to tran slate to higher levels of biological organization. Identifying specific ecosystems at risk in a scr eening-level assessment is beyond the scope of the
effort.

8.1 Receptors

The aquatic receptors likely to be exposed to quizalofop-p-ethyl include fish, invertebrates, aquatic stages of amphibians and plants living in waterways adjacent to or downstream from
treated areas.

Terrestrial receptors likely to be exposed to qui zalofop-p-ethyl include birds, mammals, reptiles, and terrestrial stages of amphibians that may occur in treated fields and terrestrial plants adjacent to, or down slope from treated areas.

8.2. Assessment Endpoints

Assessment endpoints are defined as “explicit expressions of the actual envir onmental value that is to be protected.” Operationally, the environm ental value is represente d by an ecological entity
and associated attributes or characteristics. The assessment endpoints for this ecological risk assessment will be survival, growth, and reprodu ction of terrestrial and aquatic animals and plants. Specifically, this assessment will addr ess birds, mammals, reptiles, amphibians, terrestrial and aquatic invertebrates, terrestrial an d aquatic plants, and fish. These endpoints, in turn, are meant to reflect populat ion sustainability and community diversity within ecosystems.

Assessment endpoints and toxicity data used to evaluate the as sessment endpoints are identified

in Table 2 and Table 3

.23 9. CONCEPTUAL MODEL

The conceptual model used to depict the potentia l ecological risk associ ated with quizalofop-pethyl is generic and assumes that as an herbic ide, quizalofop-p-ethyl can affect terrestrial and aquatic organisms if environmenta l concentrations are sufficiently elevated as a result of the proposed label uses. A diagram of th e conceptual model is presented in Figure 1 . All of the use scenarios for quizalofop-p-ethyl in volve spray applications such as: ground, aerial, air blast of the pesticide to foliage as well as soil inj ection. Although not eviden t from the diagram, quizalofop-p-ethyl degradation prior to runoff is explicitly considered. Runoff includes transport of quizalofop-p-ethyl and its degradate in a disso lved state as well as qu izalofop-p-ethyl and its degradate adsorbed to eroded sediment.

As there are multiple spray applications of the pesticide to foliage of the proposed labeled use patterns, degradation on the foliage between app lications is considered in the terrestrial assessments. A default foliar dissipation rate of 35 days will be used in the terrestrial risk assessments since no foliar dissip ation studies are available. Th e default value represents an upper bound on expected foliar dissipation rates across all pesticides, based on data in Willis and McDowell (1987). For aquatic assessments, the mi crobial degradation on foliage is assumed stable, but wash-off of the foliage will be c onsidered using the default wash-off coefficient assumption of 0.5 cm -1 . Spray drift will be considered in the aquatic assessments as a route of loading to the pond, with higher levels of spray drift for aer ial applications than ground spray applications.

For terrestrial assessments, spray drift is not dir ectly considered. Howeve r, since the evaluation of risk is done for on-field foliage, non-target foliage receiving spray drift should reduce pesticide loading and the assessment based on th e on-field residues which would represent an upper bound estimate. A variety of food types (e .g., short grass, long grass, broadleaf plants) will be assessed regardless of the type represented by the target crop, as a variety of food types
exist on and off the treated field.

In aquatic environment, once quizalofop-p- ethyl reaches a water body, the pesticide is partitioned between the water column, suspended se diment, and bed sediment at a ratio based on the pesticides’ physical/chemical properties. Degradation by abio tic hydrolysis, photolysis, and
microbial mediated metabolism are taken into account . The route of exposure to fish is uptake of quizalofop-p-ethyl and its degrad ate dissolved in the water column through the gills and integument.

Quizalofop-p-ethyl does not bio-acc umulate in fish. BCFs have 28-day values of 1X and 4X for exposure concentrations of 0.004 and 0.04 ml/L, respectively.

For birds and mammals, only the dietary route of exposure is c onsidered. Uncertainties may include the lack of information on exposure from soil ingestion as well as exposure from other pathways such as inhalation and dermal routes.24 Figure 1. Conceptual model of the fate/trans port and effects of qui zalofop-p-ethyl in the
environment. This updated conceptual model will be used in the next assessment which will incorporate additional applications

Food Web Dynamics Perturbing Forage or Prey Availability Habitat Alteration: impacting nesting ability, ability to seek cover, etc. Individual Terrestrial
Animals
Reduced Survival
Reduced Growth Reduced Reproduction Individual Terrestrial
Plants Seedling Emergence Vegetative Vigor Individual Aquatic
Vertebrates and
Invertebrates
Reduced Survival
Reduced Growth Reduced Reproduction

Bioaccumulation Aquatic Plant Population
Reduced
Growth Rates

and Biomass Terrestrial Animals Birds, Mammals, Reptiles, Terrestrial-phase Amphibians, Bees Terrestrial Upland Plants Wetland/ Riparian

Plants Aquatic Invertebrates Aquatic Vertebrates Aquatic Plants Quizalofop-p-ethyl applied by ground spray, aerial, airblast and soil injection

a pp lications

Volatilization/
Wind Suspension* Ground Deposition Spray Drift Runoff/

Erosion Leaching (Infiltration/ Percolation)

Terrestrial
Food Residues (foliage, fruit, insects) Upland Foliage/

Soil Riparian/
Wetland Foliage/Soil Surface Water,
Sediment

Dietary uptake Direct Contact/ Root Uptake Gill/ Integument Uptake Direct Contact/ Root Uptake Groundw

ater

Direct Ingestion

* Volatilzation is not expected to be an exposure of concern due to a low vapor pressure of 3.0 x 10 -7 mmHg@20 o C10. RISK HYPOTHESES

Hypothesis: Nontarget terre strial and aquatic animals and plants are at risk of di rect and indirect effects resulting from labele d uses of quizalofop-p-ethyl.

11. ANALYSIS PLAN

The analysis plan is the final step in problem formulation. During this step measures of exposure and measures of effect are used to evaluate the ri sk hypotheses and are listed in Tables
2 and 3 for a specific assessment endpoint. The RQ is obtained by dividing the measures of exposure for a particular assessment endpoint by the measures of effect for that endpoint.

11.1. Measures of Exposure

Measures of exposure for quizalofop-p-ethyl that will be used in this assessment are obtained from modeling efforts only, since national-scale monitoring data were not identified. Exposure
models used for this assessment include the suite of standard exposure m odels commonly used in pesticide risk assessments (EPA, 2004). Genera lly, aquatic exposure estimates are generated from EFED models and incorporate maximum pr oposed use rates and empi rically-derived fate properties. Aquatic exposure will be estima ted using the PRZM/EXAMS model and will consist of aquatic EECs derived using a water body that is vulnerable and representative of static ponds and first order waterways.

Measures of exposure for terrestrial mammals , birds, reptiles, and amphibians similarly incorporate maximum proposed use rates but rely less on fate properties. Instead, terrestrial exposure estimates are derived directly from em pirically determined observations of pesticide
residues on various terrestrial food items. For numerous applications for a given use, the exposure model incorporates a fi rst-order decay rate dependent on the soil half-life of the chemical. In place of unavailable foliar dissipation data, the default foliar dissipation half-life of 35 days will be used. The currently used terrestrial exposure model is TREX v.1.3.1.

Exposure to terrestrial plants will be estim ated using the TerrPlant model that assumes quizalofop-p-ethyl drifts or moves with runoff to adjacent areas. However, acceptable terrestrial plant toxicity data has not been submitted. Theref ore, risks to terrestrial plants can not be
determined.

Based on preliminary EECs and the assumptions di scussed above, chronic risks at the highest labeled application rate are expe cted for all non-listed and listed mammals and estuarine marine aquatic invertebrates (0.4125 lbs a.i./A per season). Risks are e xpected as well for non-listed and listed species of terrestrial plants inhabiting semi-aquatic and dry areas based on exposures of quizalofop originating from the maximum application rate. Because of the potential risk from
direct effects to the listed and non-listed taxa described above, should exposure occur, listed species in all taxa may potentially be affected indirectly due to alterations in their habitat ( e.g ., food sources, shelter, and areas to reproduce).

25If the planned ecological risk assessment continues to indicate that quizalofop may potentially impact, either directly or indire ctly, listed species or critical habitat, and therefore does not support a “not likely to adversely affect” determination, further refinements will be made. This will involve determining whether use of quizalofop “may affect” a particular listed species, and if so, whether it is “likely to adversely affect” the species, or in the case of designated critical habitat, whether use of the pesticide may destroy or adversely modify any principle constituent elements for the critical habitat, and if so, whet her the expected impacts are “likely to adversely affect” the critical habitat. The first step in the process is to improve the exposure estimates based on refining the geographic proximity of qu izalofop use and the li sted species and/or critical habitat. If there is no geographi c proximity, this information would support a determination that quizalofop use will have no effect on the species or critical habitat. If after conducting the first step of this analysis the Agen cy determines that geographic proximity exists, both potential direct effects a nd any potential indirect effect s of the pesticide use will be examined. This process is consistent with the Agency's Overview Document. The Agency will consult as necessary with the U.S. Fish and Wildlife Service and National Marine Fisheries Service (collectively ‘the Services’), c onsistent with the Services' regulations.

If the screening level risk assessment identifies potential concerns for indirect effects on listed species, the next step for EPA and the Services would be to identify which listed species and critical habitat are potentially implicated. Anal ytically, the identification of such species and critical habitat can occur in either of two ways. First, the agencies could determine whether the action area overlaps critical habita t or the occupied range of any listed species. If so, EPA would examine whether quizalofop potential impacts on non-endangered species would affect the listed species indirectly or directly aff ect a constituent element of the cri tical habitat. Alternatively, the agencies could determine which listed speci es depend on biological resources, or have constituent elements that fall into, the taxa th at may be directly or indirectly impacted by quizalofop. Then EPA would determine whether the use of quizalofop ove rlaps the critical habitat or the occupied ra nge of those listed species.

11.2. Measures of Effect

Aquatic plants and animals

(1) Freshwater Fish

Four acute toxicity studies using both the bluegi ll sunfish (Lepomis macrochirus) and rainbow trout (Oncorhynchus mykiss) indicated that quizalofop- ethyl is slightly to very highly toxic to freshwater fish on an acute toxicity basis based on values of LC 50 460 ppb ( MRID 00146951),

LC 50 870 ppb ( MRID 00146680), LC 50 10720 ppb ( MRID 00128210), LC 50 2820 ppb ( MRID 00128210), . The bluegill sunfish was the most sensitive species tested with an LC 50 value of 460 ppb (MRID 00128210). EFED used the LC 50 value of 460 ppb for evaluating acute risks to freshwater fish. The guideline requirement for 72-1c and 72-1a acute aquatic fish was fulfilled (MRID 00146951).

A freshwater fish early life-stage chronic toxi city test on fathead minnow (Pimephales promales)

26was used to evaluate the chroni c toxicity of quizalofop-ethyl. Re sults from the study indicated a No Observed Adverse Effect Level (NOAEL) of 11 ppb based on decrease in larval survival, weight. EFED used this value for evaluating ch ronic risk to freshwater fish. This guideline requirement for 72-4a for the early life-stage fi sh was classified as supplemental (MRID150109).

(2) Freshwater Invertebrates

Three acute freshwater toxicity tests using the Daphnia magna indicated that quizalofop-ethyl is moderately toxic to freshwater invertebrate s on an acute toxicity basis based on the EC 50 values of 2120 ppb (MRID 00128210), 6400 ppb (MRID 00146951) and 3900 ppb (MRID 411616-01).
EFED used the EC 50 of 3900 ppb to evaluate risks to freshw ater invertebrates which was not the most sensitive value. Therefore, the EC 50 of 2120 ppb value will be assess ed to use in future risk assessments. Although, the guideline requirement for 72-2a was fulfilled for the acute
freshwater invertebra te study based on the EC 50 of 3900 ppb, the EC 50 of 2120 ppb value will be assessed to use in future use in risk assessments(MRID 411616-01) (MRID 00128210).

A freshwater invertebrate early life-stage toxicity test for freshwater invertebrates exposed to quizalofop-ethyl was not submitted to the Agency. No early life-stage invertebrate studies were
submitted for freshwater invertebrates. Estimat ed values from ACRs will be accepted pending submission of requested a chronic estuarine marine inverteb rate (mysid) study conducted on quizalofop-p-ethyl.

(3) Estuarine/Marine Fish

One estuarine/marine fish acute toxicity test, using the sheepshead minnow (Cyprinodon variegates), test indicated that quizalofop-ethyl is mode rately toxic to estuarine/marine fish on an acute toxicity basis based on the LC 50 value of 1400 ppb. Therefore, EFED used the LC 50 value of 1400 ppb for evaluating acute risks to estuarin e marine fish. The guide line requirement 72-3a for the acute toxicity to estuarine marine fish was fulfilled. (MRID 402422-09).

No early life-stage estuarine marine fish studies were submitted to the Agency. Estimated values
from ACRs will be used in future risk assessments from acute and chronic freshwater fish and acute estuarine marine fish toxicity studies.

(4) Estuarine/Marine Invertebrates

Two estuarine/marine acute toxicity tests exposing the mysid shrimp, Americamysis bahia , to quizalofop-ethyl indicated that qu izalofop-ethyl is highly toxic to estuarine/marine invertebrates on an acute toxicity basis based on the EC 50 values of 250 ppb (MRID 402422-05) and 150 ppb (MRID 402422-04). EFED used the EC 50 of 250 ppb to evaluate risks to estuarine marine invertebrates which was not the most sensitive value. Therefore, the EC 50 150 ppb value will be
assessed to use in future risk assessments. Although, the guidel ine requirement for 72-2a was fulfilled for the acute estuarine marine invertebrate study based on the EC 50 of 250 ppb, the EC 50

27of 150 ppb value will be assessed to use in future use in risk assessments (MRID 402422-05) (MRID 402422-04).

No early life-stage estuarine marine invertebra te studies were submitted to the Agency. Since no
chronic studies were submitted for either freshwat er or estuarine marine aquatic invertebrates and exceedences may occur for higher use rates (pineapple and ornamental turf) especially for estuarine marine invertebrates, EFED requests an early life-stage estuarine marine invertebrate (mysid) study conducted on quizalofop-p-ethyl. to quantify risks for estuarine marine invertebrates. In addition, the NOA EC values from this estuarine marine invertebrate study will
also be used to estimate NOAEC values for freshwater invertebrates derived from ACRs.

(5) Estuarine/Marine Mollusks

An estuarine/marine acute shell deposition toxicity test exposing the eastern oyster to quizalofopethyl indicated that quizalofop- ethyl is highly toxic to estuar ine/marine mollusks on an acute toxicity basis based on the EC 50 value of 187 ppb (MRID 402422-07). An Eastern oyster-larvae (bivalve) study was sited in earlier assessments as EC 50 79 ppb on canola (March 1997) and mint (February 1993) however no references were made.

(6) Aquatic Plants

The tier I test with non-vascular green alga Selenastrum capricornutum exposed to quizalofop-pethyl showed a maximum of 19 % inhibition at the mean measured test concentration of 1770 ppb (MRID 432356-01). Since an EC50 was not determin ed from any of the tier I aquatic plant tests, the value of EC50 > 1770 ppb w ill be used in future risk assessments to determine risks to aquatic non-vascular plants e xposed to quizalofop-p-ethyl.

Two additional Tier I aquatic non-vascular plant studies using the freshwater diatom Navicula pelliculosa and the estuarine/marine diatom Skeletonema costatum , showed a maximum of 3%
inhibition at a test concentrati on of 98 ppb and 1.8% stimulation at a test concentration of 82 ppb exposed to quizalofop-p-ethyl, resp ectively ( MRID 432709-01 and MRID 432709-02). The aquatic vascular plant Lemna gibba from a Tier I study, showed no adverse response to quizalofop-p-ethyl exposure with EC50 >82.8 ppb (MRID 432585-01).

The results of the Anabaena flos-aque aquatic plant study (MRID 432356-02) conducted on quizalofop-p-ethyl was not incorporated in the 2005 risk assessment but will be in future risk

assessments.

Non vascular plant NOAEC values were not determined for quizalofop-p-ethyl. In the absence of those data, EFED based its risk estimation for non vascular plants on data from the NOAEC for analog fenoxaprop-p-ethyl (27 ppb). It is understood that fenoxaprop- p-ethyl is more toxic ethyl to non vascular plants than quizalofop-p-ethy l (EC50 of 1770 ppb for quizalofop-p-ethyl vs 430 ppb for fenoxaprop -p-ethyl for Selanastrum capriconutum, the most sensitive species tested for

28both chemicals), therefore using data from fenoxaprop-p-ethyl may overestimate risk for quizalofop-p-ethyl.

No effects occurred at the hi ghest concentration of 82.8 ppb for lemna gibba , therefore EFED will use the NOAEC value of 82.8 ppb for vascular plants in future risk assessments.

Terrestrial organisms

(1) Birds

Five studies on the acute toxic ity of quizalofop-ethyl (oral and dietary toxicity) to birds indicated that quizalofop-ethyl is practically non-toxi c to the mallard duck (water-fowl) and the bobwhite quail (upland game bird) on acute oral and dietary toxicity basis. The LD 50 values for the avian acute oral toxicity tests were: Mallard duck LD 50 >2,000 mg kg-bw and Bobwhite Quail LD 50 >2,000 mg /kg-bw. The LC 50 values for the avian acute diet ary toxicity tests were as
follows: Mallard Duck LC 50 >5,000 mg kg-diet; Bobwhite qua il LC50 >5,000 mg /kg-diet; and Bobwhite quail LC50 >5620 mg/kg-diet. Therefore, EFED used the LD 50 >2,000 mg kg-bw and

LC 50 >5,000 mg kg-diet values for evaluating acute oral a nd dietary risks to birds. NOAEC values were not determined. The guideline requi rements 71-1 and 71-2 for the acute oral and dietary toxicity to birds were fulfilled. (MRID 00128210, MRID 00147574).

Based on provisional review of tw o avian chronic reproductive t oxicity studies using quizalofopp-ethyl, it appears that quizalofop-p-ethyl does not pose potential reproducti ve inhibition to birds based on a chronic toxicity ba sis. No reproductive effects we re observed in a bobwhite quail study, resulting in a NOAEC value of 1000 ppm (MRID 466071-01). However, there did appear to be a reduction in hatchability at the highe st dose tested (1000 ppm a.i.) in the mallard duck study. Ther e was an apparent reduction in hatchlings as a percentage of live 3-week embryos in the 1000 ppm a.i. tr eatment group, resulting in a NOAEC of 500 ppm (MRID 466071-02). However, it is not clear before a full review of th e data whether this
observed effect was statistic ally significant (p>0.05).

(2) Mammals

Wild mammal testing is required on a case-by-case basis only, and is dependent on the results of lower tier laboratory mammalian st udies, intended use patterns, a nd pertinent environmental fate characteristics. In most cases, rat or mouse toxi city values obtained from the Agency’s Health Effects Division (HED) are used as surroga tes for wild mammal toxicity testing. The acute toxicity of quizalofop-et hyl was evaluated using the labor atory rat. The acute toxicity of quizalofop-ethyl differed between male and female rats with females showing greater sensitivity than males. The LD 50 values were 870 mg/kg bw (fema1es) and 1088 mg/kg bw(males) and a combined LD 50 value of 979 m a g for both males and females. For the purposes of this risk assessment, the lowe r male-specific value of 870 mg/kg was used.

29As with the mammalian acute toxicity data, th e mammalian chronic toxic ity data are obtained from the Agency's Health Effects Division (HED ) and are considered representative of wild mammals. These studies provide adequate toxic ity data on the potential effects of chronic quizalofop-p-ethyl exposure in mammals. In rats , the No Observable Adverse Effect Level (NOAEL) was 5mgkg/day for a decreased in male and female pup body weight, which corresponds to approximately to a dietary level of 100 ppm (mg a. i.kg feed). It should also be

noted that the male adults and some male pups experienced testicular atrophy. 

### In females signs of uterus atrophy were noticeable in the adults and the offspring.

.

(3) Terrestrial Invertebrates

Acute toxicity of quizalofop-ethyl to terrestrial non-targeted beneficial insects was assessed where honey bees, Apis millifera, were exposed to quizalofop-ethyl via acute contact route. The

acute contact 

### LD 50 value was 50ug/bee which classifies quiza lofop-ethyl as practically non-toxic to non-targeted beneficial terrest rial insects on an acute contact toxicity basis. The study was classified as acceptable (MRID 150942).

(4) Terrestrial Plants

At this time EFED is requesting that the regi strant re-submit terrestrial plant toxicity tests (e.g., Seedling Emergence and Vegetative Vigor Te sts) with the typical-end-use product of quizalofop-p-ethyl. Previously submitted terrestrial plant studies were deemed unacceptable by EFED biological reviewers.

The measures of effects will either be the resu lts of actual tests or will be derived or assumed based on other data. Where data is lacking and extrapolated effects endpoi nts cannot be reliably estimated, risk will be presumed unless data is submitted. In cases where risk is presumed, but cannot be quantified based on lack of data, cons ervative assumptions will be made, and some analyses will not be able to be conducted.

Assessment endpoints and toxicity data used to evaluate the as sessment endpoints are identified

in Table 3 and Table 4

.

30Table 3. Summary of terrestrial asse ssment endpoints and proposed measures
of effects for the screen ing level risk assessment of quizalofop-ethyl and quizalofop-p-ethyl. All studies are conducted on quizalofop-ethyl unless
otherwise indicated

Assessment Endpoint Measurement Endpoint

Avian Survival Northern bobwhite quail Colinus virginianus LD 50 > 2000mg/kg bw Mallard duck Anas platyrhynchos LD 50 > 2000 mg/kg BW

Avian Reproduction and/or
Survival*** Northern bobwhite quail (Colinus virginianus) NOAEC 1000 mg/kg diet Mallard duck (Anas platyrhynchos) NOAEC 500 mg/kg diet

Mammalian Survival Laboratory rat Rattus rattus 870 mg/kg-bw

Mammalian Reproduction and/or
Survival Laboratory rat Rattus rattus NOAEC 100 mg/kg/diet NOAEL 5 mg/kg/day

Terrestrial Plants Survival and
Growth*** Seedling emergence and vegetative vigor submitted studies were classified as unacceptable based on errors in toxicity determination and plant testing based on technical grade active ingredient (TGAI) instead of typical end use (TEP). These studies were conducted on quizalofop-p-ethyl. No quizalofop-ethyl seedling emergence and vegetative vigor studies were submitted.

Non-target Beneficial Insect Survival Honey bee (acute contact) Apis meliferus 50 μg a.i./L

31Table 4. Summary of aquatic assessmen t endpoints and proposed measures of effects for the screening level risk assessm ent of quizalofop-ethyl and quizalofop-pethyl. All studies are conducted on quizalofop-ethyl unless otherwise indicated

Assessment Endpoint Measurement Endpoint

Freshwater Fish Survival Rainbow trout (Oncorhynchus mykiss)

LC 50 870 ppb
Bluegill sunfish (Lepomis macrochirus)

LC 50 460 ppb

Freshwater Fish Reproduction
an/or Survival Rainbow trout (Oncorhynchus mykiss) NOAEC 11 ppb

Freshwater Invertebrate Survival Water flea (Daphnia magna)

EC 50 3900*

Freshwater Invertebrate Reproduction and/or Survival NOAECs will be estimated in future assessments based on ACRs, pending submission of a chronic estuarine marine invertebrate (mysid) toxicity study conducted on quizalofop-p-ethyl.

Marine/Estuarine Fish Survival Sheepshead minnow (Cyprinodon variegatus) EC 50 1400 ppb

Marine/Estuarine Fish Reproduction and/or Survival Chronic NOAEC 33ppb**

Marine/Estuarine Invertebrate
Survival Eastern oyster Crassostrea virginica EC 50 187 ppb

Mysid shrimp Americamysis bahia EC 50 250 ppb*

Marine/Estuarine Invertebrate Reproduction and/or Survival Request submission of a chronic estuarine marine invertebrate (mysid) toxicity study conducted on quizalofop-p-ethyl.

Aquatic Vascular and Non-vascular
Plant Survival and Growth*** Tier I aquatic vascular plant ( Lemna gibba ) EC50>82.8 ppb
Tier I aquatic vascular plant ( Lemna gibba ) NOAEC 82.8 ppb will be
used in future risk assessments
Tier I non-vascular plant (Selanastrum capricornutum) EC50>1770 ppb

* The most sensitive EC 50 values for endpoints were not used to calculate RQs and will be reviewed for future risk assessments. Mysid shrimp, EC 50 150 ppb and acute freshwater invertebrate EC 50 2120 ppb ** ( 2005 risk assessment calcula ted incorrectly as 513.3 )

*** Studies conducted on quizalofop-p-ethyl

3211.3. Preliminary Identification of Data Gaps for Fate and Ecological Assessment

Table 5 below, identifies fate and ecological studie s, which are missing or are not acceptable, and may be requested to asse ss risk to the environment:

Table 5. Preliminary Identification of Da ta Gaps for Fate and Ecological Assessment*

Fate and Ecological
Taxa studies Description of study Projected status of data

gap Basis for decision

Estuarine/marine fish Chronic study for
estuarine/marine fish was not
submitted Study not requested Acute to chronic ratios will be sufficient to not request study

Chronic freshwater and estuarine
marine invertebrate studies Chronic toxicity data to
freshwater and estuarine marine
invertebrate studies were not
submitted Study requested for chronic
estuarine marine invertebrate(mysid) conducted on quizalofopp-ethyl. No study is requested for
chronic freshwater invertebrate Since no chronic invertebrate
studies were submitted and
chronic invertebrate exceedences may occur with
estuarine marine invertebrates at higher application rates (pineapple and ornamental turf),
a chronic estuarine marine invertebrate study is requested.
ACRs will be sufficient to
evaluate chronic freshwater invertebrates from receipt of
the chronic estuarine marine invertebrate study.

Seedling Emergence and Vegetative Vigor Terrestrial Plant
studies Studies submitted for terrestrialplants based on quizalofop-pethyl were determined unacceptable due errors in toxicity determination and the
use of TGAI instead of TEP
formulation. Additional studies requested Seedling Emergence and Vegetative Vigor Terrestrial
Plant studies conducted on quizalofop-p-ethyl are necessary
to determine risks to terrestrial plants and buffers from spray
drift.

Existing fate and eco-toxicity data on the degradate (quizalofop acid) to determine risks to aquatic organisms Existing fate studies and ecotoxicity data were not submitted on the degradate (quizalofop acid) Existing fate and eco-toxicty data from the registrant are not requested for the degradate at this
time. The parent quizalofop-p-ethyl can be easily converted to quizalofop acid. Additional ecotoxicity data such as; sediment toxicity studies are not requested for the degradate at
this time unless additional fate and ecotoxicity data indicate an increased toxicity exposure to aquatic organisms.

33Non-vascular plant study

(Selanastrum capricornutum) Maximum growth inhibition
observed was 19% from a tier I study and a NOAEC could not be
determined Additional study not requested Since a maximum growth
inhibition observed was 19% from a tier I study and a NOAEC a Tier II test would quanitify risks. However, EFED will quantify risks to listed species through estimated values and analog data.

Foliar dissipation residue data Fo liar dissipation data studies or
related data were not available Study not requested Chronic mammal exceedences
will still occur with current NOAEC 100 mg/kg diet endpoint even if the halflife is 1 day. Therefore,A default foliar dissipation rate of 35 days will be used in the modeling in place of the data if study is not
submitted.

*The fate and transport database for quizalofop-p-ethyl is complete.

12. OPEN LITERATURE

Previous assessments did not include open lite rature data as identif ied by ORD, MED ECOTOX literature search program.

13. NEW ASSESSMENT DECISION

EFED needs additional data (or will apply alte rnate effects assumptions) and would need to conduct new assessments for all registered out door uses. The new assessments are needed because of the following:

(a) Not all toxicity data were av ailable for the 2005 assessment. These data include: chronic study in estuarin e/marine fish (72-4c), chronic life cycle toxicity studies in invertebrates (72-4b, 72- 4d), seedling emergence and vegetative vigor for terrestrial plants (122-1 /123-1) and aquatic toxicity data for the quizolofop acid degradate.

(b) Currently used models were not included in all risk assessments.

(c) Aquatic assessments were performed on “old” scenarios and models. New assessments are required to accurately asse ss toxic effects to aquatic.

(d) Some uses and application type scenarios were not assessed for ecological risk or
did not include current te rrestrial or aquatic models.
These scenarios include Non-Food/Non-feed uses (alfalfa, beets, car rot ( including tops), swiss chard, grasses grown for seed, cott onwood/poplar plantati ons, non-agricultural uncultivated areas/soils, onion, ornamental trees, shade trees, radish, spinach and for Food and Feed uses (agricultural fallow/idlela nd, succulent and dried beans, snap beans,

34chinese cabbage, canola, eucal yptus, rape, cotton, crambe , garlic, lentils, mint, peppermint and spearmint, dried and succulent peas, pineapple, soybeans, sugarbeets including tops.

(e) Open literature data, as identified by ORD, MED ECOTOX literature search program, were not included in previous assessments.

(f) A Tier II drinking water assessment of surface water was performed based on Index Reservoir settings (Oct ober 28, 2005, Section 3 New use registration request for quizalofop-p-ethyl (TARGA TM ) on sunflowers, flax, wheat and barley (DP 310868) with the highest seasonal applicatio n rates of 0.1925 and 0.20625 lb ai/A. The simulation produced estimated drinking wate r concentrations (EDWC) of 5.25 ppb for acute exposure, 1.99 ppb for chronic expos ure, and 1.34 ppb for cancer exposure. For ground water sources, the Ti er I drinking water predic ted EDWC of 0.15 ppb for both acute and chronic exposure. Fo r this drinking water exposur e purpose, the assessment is focused on the specific label uses. All crop uses for quizalofop-p-ethyl according to the TARGA label are tabulated below based on 2005 drinking wate r exposure assessment.

Use Modeling Scenario Seasonal Rate Application Scheme
Mint OR 0.20625 (lb/ac) 2 applications Dry Beans MI 0.1925 2 applications Sugarbeets MN 0.171875 2 applications
Flax 0.165 2 applications
Canola and Crambe ND 0.12375 2 applications

Cotton CA, MS, NC 0.12375 2 applications Soybeans MS 0.12375 2 applications
Sunflowers 0.12375 2 applications
Lentils 0.09625 2 applications Dry and Succlent Peas 0.09625 2 applications Snap Beans OR 0.09625 2 applications Barleys 0.0825 1 application
Wheat ND 0.0825 1 application

If additional crop uses have higher seasonal application rates, a new drinking water assessment needs to be completed.

14. SUMMARY OF RISK

Summary of Risks Identified for Use on Sunflowers, Flax, Wheat and Barley (DP 310868)

Estimated LOC exceedences for are summarized in Table 6 below. The risk conclusions are based on previously conducted risk assessments and anticipated exceedences for maximum use
rates. The most recent risk assessment conducted on sunflowers, flax, wheat and barley (D310868, 2005) employed the more current models us ed in the ecological risk assessment. The

35label maximum single application rates for sunflowe rs, flax, wheat and barley are as follows: (1)
sunflowers with a maximum seasonal rate of 0.12 lb ai /acre; (2) flax with a maximum seasonal rate of 0.165 lb ai /acre; and 

### (3) wheat and barley with a maximum seasonal rate of 0.08 lb ai

acre.

The maximum use and application rate for quizalof op-p-ethyl is for pineapples, ornamental and/ or shade trees at 0.4125 lb ai/A (2 applications @ 0.2063 lb ai/A and 7 day intervals). The 7 day interval was applied because label information did not specify intervals between applications. Anticipated LOC exceedences from the above maximum use rate would be chronic mammal with RQs ranging from 1.72 to 8.18. Terrestrial pl ants can not be assessed due to lack of acceptable data, however exceedences are anticipat ed for all modeled scenarios due to the chemical properties and mode of action of quizalofop-p-ethyl.

Aquatic EECs for the maximum application rates for labeled crops and PRZM/EXAMS scenarios need to be determined. However, chro nic risks to estuarine marine invertebrates for quizalofop-p-ethyl are uncertain based on estimated values derived from the acute and chronic freshwater fish (rainbow trout). The RQ of 0.64 for chronic estuar ine invertebrates derived from
the estimated values for the 0.165 lb ai/A application scenario is close in value to the chronic LOC = 1.0 Table 7). Therefore, exceedences are anti cipated for chronic risk to estuarine marine invertebrates with higher application rates. Si nce no chronic studies were submitted for chronic
risks to either freshwater or estuarine marine invertebrates and uncertainty exists for possible
LOC exceedences for chronic risks to estuarine marine invertebrates for higher application rate scenarios, a chronic study for estuarine mari ne invertebrate (mysid ) study is requested.

Table 6. LOC exceedences for quizalofop-p-ethyl from use on sunflowers, flax, wheat and barley.*

Use Endpoint Birds Mamma
ls Terr.
Plants Insects FW fish SW
Fish FW

Inverts SW

Inverts Aquatic
Plants

Acute Not

assesse d sunflowers, flax, wheat and barley Reproductive 9

Acute 9 pineapple,
ornamental
and/ or
shade trees Reproductive 9 9

• All risk conclusions are based on previ ously conducted risk assessments (D310868) Degradate toxicity was not
included
9

Risk is anticipated to be > any of the Agency’s LOC
Blank cells indicate no LOC exceedences

Aquatic Organisms

Based on the Tier II (PRZM/EXAMS) modeling, the 2005 risk assessment on flax, sunflowers, barley and wheat showed no acute LOC exceeden ce for aquatic organisms. The highest modeled application rate scenario for the a bove crops was flax, which was based on 1 aerial application at a single ra te of 0.165 lb ai/acre. Table 7 summarizes the quizalofop-p-ethyl EECs (2.57 μg a.i./L (peak), 2.33 μg a.i. /L (21-day), 2.03 μg a.i./L (60-da y)) and the toxicity data used
in the assessment on flax.

36Endpoint selection for mysid shrimp and daphni a magna will be reviewed since the most sensitive endpoints were not selected for RQ calculation from the 2005 assessment. For acute toxicity to mysid shrimp the most sensitive endpoint EC 50 150 ppb and for Daphnia magna the most sensitive endpoint was EC 50 2120 ppb. The NOAEC for estuarine marine fish was calculated incorrectly as 513.3 ppb and would have to be determined based on the most sensitive endpoint selected. NOAECs were not determined fo r the Tier I vascular and non-vascular plants to address listed species concerns. Since no eff ects occurred at the single dose concentration value of 82.8 ppb for Lemna gibba , this value will be used as the NOAEC for vascular plants in future risk assessments. Although a 19% inhibition occurred based Selanstrum capricornutum (Tier I study), an additional study to determine a NOAEC value will not be requested at this time for non-vascular plants because estimated EECs would result in RQs which are below the LOC based on analog data. Many DERS are based on 1985-1988 statistical programs and outdated criteria, therefore these DERs will be reviewed and updated to current EPA standards. An Eastern oyster-larvae (bivalve) study wa s sited in earlier assessments as EC 50 79 ppb (on Canola March 1997 and Mint February 1993).

37Table 7. Aquatic EECs and RQs for quizalofop-p- ethyl based on a single application of 0.165 lb ai/acre per season (the max.(EECs) label application rate to flax).

Taxa Toxicity EEC* RQ
Acute LC50: 460 ppb 2.57 ppb (peak EEC) RQ<LOC=(<0.01) FW Fish Chronic NOAEC: 11 ppb 2.03 ppb (60-day EEC) RQ<LOC=(<0.01)

Acute EC 50 : 3900 ppb*** 2.57 ppb RQ<LOC=(<0.01) FW Invertebrate

Chronic NOAEC ++

Estimated NOAEC value of 26.8 based on an acute EC50 value of 2120 ppb would result in RQ< LOC=0.09  2.57 ppb N/A

Acute EC 50 : >82.8 ppb 2.57 ppb RQ<LOC=(<0.02) FW Vascular Aquatic Plants NOAEC: was not determined ( Lemna gibba ) tier 1stud y . However, the NOAEC value of 82.8 ppb will be used
in future risk assessments 2.57 ppb N/A

Acute EC 50 : (>1770ppb Selenastrum capricornutum ) 2.57 ppb RQ<LOC=(<0.01) Non-vascular Plants and Algae

NOAEC:not determined 2.57 ppb N/A

Acute LC 50 1400 ppb (Sheepshead minnow) 2.57 ppb RQ<LOC=(<0.01) Estuarine/Marine

Fish
Chronic NOAEC 33ppb** 
( 2005 risk assessment calculated incorrectly as 513.3 ) 2.03 ppb RQ<LOC=(<0.06)

Mysid shrimp, EC 50 : 250 ppb*** 2.57 ppb RQ<LOC=(<0.01) Estuarine/Marine

Invertebrates

Chronic NOAEC: ++

Estimated NOAEC value of 3.6 based on an acute EC50 value of 150 ppb would result in RQ< LOC=0.64**** 2.33 ppb (21-day EEC) N/A

Acute EC 50 : 187 ppb 2.57 ppb RQ<LOC=(<0.01) Estuarine/Marine

Mollusc

*Derived for one application of 0.165lb a.i./acre aerial application (flax) ** Chronic NOAEC derived using acute to chronic ratio due to lack of submitted data.

*** The most sensitive EC 50 values for endpoints were not used to calculate RQs and will be reviewed for future risk assessments. Mysid shrimp, EC 50 150 ppb and acute freshwater invertebrate EC 50 2120 ppb **** Estimated values were derived from quizalofop-eth yl acute and chronic freshwat er fish (rainbow trout)

studies

++ Data not available

There are insufficient data to establish a defin itive toxicity endpoint for estuarine marine and freshwater invertebrate chronic effects for qu izalofop-ethyl. To estimate potential chronic
estuarine marine and freshwater invertebrate endpoints for qui zalofop-ethyl th e relationship
between established acute and chronic freshwat er fish (rainbow trout ) endpoints for quizalofopethyl were considered. A ratio was determined between the acute and chronic freshwater fish

38endpoints used for RQ calculation from quizal ofop (870 ppb acute freshwater fish (rainbow trout)/ 11 ppb chronic freshwater fish (rainbow trout) =79). Th e largest ratio between acute endpoint and chronic endpoint wa s applied to the most sensit ive quizalofop acu te estuarine
marine and freshwater invertebrate value to de rive estimated chronic e ndpoints as described in
Table 8.

Table 8 Summary of Calculations for Estimated Endpoints

ENDPOINT DESIRED For Quizalofop-p-ethyl Acute/Chronic Quizalofop-ethyl =ratio Acute Endpoint quizalofop/ratio= endpoint Estimated Endpoint

Chronic freshwater invertebrate daphnia( endpoint in section 3)* 870 ppb/11 ppb=79 rainbow

trout 2120 ppb/79=26.8 ppb NOAEC 26.8 ppb
Chronic estuarine marine invertebrate mysid( endpoint in section 3**) 870 ppb/11 ppb=79 rainbow

trout 150 ppb/79=1.8 ppb NOAEC 1.8 ppb

*Chronic freshwater invertebrate daphnia : 2.57 ppb/NOAEC 26.8 ppb= RQ 0.09 for 0.165 lb ai/acre
**Chronic estuarine marine invertebrate mysid : 2.57ppb/NOAEC 1.8 ppb= RQ 1.4 for 0.165 lb ai/ acre

Terrestrial Organisms

No acute or chronic exceedences occurred for birds from the 2005 assessment for sunflowers, flax, barley and wheat. Also, no acute or chr onic exceedences will occur for birds based on the proposed highest maximum seasona l rate of 0.4125 lb a.i./A (2 applications @ 0. 2063 lb ai/A and 7 day intervals) and the non-definitive LD 50 bw (>2000 ppm) and LC 50 (>5000 ppm) diet. Acute RQs were not calculated for birds from uses on sunflowers, flax, barley and wheat.. However, because the LD 50 bw (>2000 ppm) and LC 50 (>5000 ppm) diet were greater than the highest dosage administered for bobwhite quail, quizalofop was characterized as practically nontoxic to birds.
Based on provisional review of tw o avian chronic reproductive toxi city studies using quizalofopp-ethyl, it appears that quizalofop-p-ethyl does not pose potential reproducti ve inhibition to birds based on a chronic toxicity basis. Chronic RQs ranged from <0.01- 0.08 from th e NOAEC 500 mg/kg-diet value and <0.01-0.04 NOAEC 1000 mg/kg-diet value from uses on sunflowers, flax, barley and wheat.

Table 9

. Avian dietary based chronic RQ values based on a bobwhite quail NOAEC=1000 and a mallard duck NOAEC= 500 mg/kg for 0.12, 0.17 and 0.08l b ai/A application scenarios derived
from the 2005 risk assessment.

39Table 9. Avian dietary-based chronic RQ value s for proposed uses of Quizalofop-p-ethyl based on upper-bound Kenaga residues. (Bobwhite Quail NOAEC=1000; and Mallard duck NOAEC= 500 mg/kg)

Use/App.

Method Application Rate lbs. ai/A

(# app / interval, days) Food Items Upper Bound EEC (mg/kg) a Chronic RQ

(EEC/ NOAEC)

Short grass 28.80 0.06 1

0.03 2

Tall grass 13.20 0.03 1

0.01 2

Broadleaf plants/small insects 16.20 0.03 1

0.02 2 Sunflower 0.12/ 1 application

Fruits, pods, seeds, and large
insects 1.80 <<0.01 1

<<0.01 2

Short grass 40.80 0.08 1

0.04 2

Tall grass 18.70 0.04 1

0.02 2

Broadleaf plants/small insects 22.95 0.05 1

0.02 2 Flax 0.17/ 1 application

Fruits, pods, seeds, and large
insects 2.55 0.01 1

<0.01 2

Short grass 19.20 0.04 1

0.02 2

Tall grass 8.80 0.02 1

0.01 2

Broadleaf plants/small insects 10.80 0.02 1

<0.01 2 Barley/Wheat 0.08/ 1 application

Fruits, pods, seeds, and large
insects 1.20 <0.01 1

<0.01 2

1

. The mallard duck NOAEC of 500 mg/kg/diet was used in estimating chronic RQs 2

. The bobwhite quail NOAEC of 1000 mg/kg/diet was used in estimating chronic RQs

No acute LOC exceedences occurred for 15g, 35g and 1000g mammals that consume short grass, tall grass, broadleaf plan ts/small insects, fruits pods large insects and seeds for all modeled scenarios (2005 assessment) Table 10. No acute LOC exceedences will occur for mammals based on the proposed highest maximum seasonal rate of 0.4125 lb ai/A (2 applications@ 0.2063

40lb ai/A and 7 day intervals).
Chronic LOCs were exceeded for 15 g and 35 g mammals that consume short grass, tall grass, broadleaf plants/small insects and 1000 g mammals that consume short gr ass with chronic RQs ranging from 0.01 to 3.54 for upper-bound Kenaga residues (2005 assessment Table 11). The chronic RQs were also exceeded for the mean Kenaga values as shown in (2005 assessment)
Table 12 . It is therefore expected that higher appli cation rate use scenarios will result in even greater chronic RQs exceedences for mammalian organisms.

Therefore, chronic exceedences (dose based) will occur for mammals based on the proposed highest maximum seasonal rate of 0.4125 lb ai/A (2 applications@ 0.2063 lb ai/A and 7 day intervals) with RQs ranging from 0.05 to 8.8.

Table 10. Mammalian dose-based acute RQ values for proposed uses of Quizalofopethyl based on a rat LD 50 = 870 mg/kg-bw and upper-bound Kenaga values.

Mammalian Acute Risk Quotients (upper-bound Kenaga residues) Use/App.

Method Application
Rate lbs. a.i./A

(# app / interval, days) Body Weight, g Short
Grass Tall Grass Broadleaf
Plants/Small

Insects Fruits/pods/

large insects Seeds

15 0.01 0.01 0.01 <0.01 <0.01

35 0.01 0.01 0.01 <0.01 <0.01 Sunflower 0.12/ 1 application

1000 0.01 <0.01 <0.01 <0.01 <0.01

15 0.02 0.01 0.01 <0.01 <0.01

35 0.02 0.01 0.01 <0.01 <0.01 Flax 0.17/ 1 application

1000 0.01 <<0.01 0.01 <0.01 <0.01

15 0.01 <0.01 0.01 <0.01 <0.01

35 0.01 <0.01 <0.01 <0.01 <0.01 Barley and
Wheat 0.08/ 1 application

1000 <<0.01 <0.01 <0.01 <0.01 <0.01

41Table 11. Mammalian dose-based chronic RQ values for proposed uses of Quizalofop-pethyl based on a rat reproductive NOA EL of 5 mg/kg /day and upper-bound Kenaga
residues.

Mammalian Chronic Risk Quotients (upper-bound Kenega values)

Use/App.

Method Application
Rate lbs. a.i./A

(# app / interval, days) Body Weight, g Short
Grass Tall Grass Broadleaf
Plants/Small

Insects Fruits/pods/

large insects Seeds

15 2.50* 1.15* 1.41* 0.16 0.03

35 2.13* 0.98 1.20* 0.13 0.04 Sunflower 0.12/ 1 application

1000 1.14* 0.52 0.64 0.07 0.02

15 3.54* 1.62* 1.99* 0.22 0.05

35 3.02* 1.39* 1.70* 0.19 0.02 Flax 0.17/ 1 application

1000 1.62* 0.74 0.91 0.10 0.02

15 1.67* 0.76 0.94 0.10 0.02

35 1.42* 0.65 0.80 0.09 0.023 Barley and
Wheat 0.08/ 1 application

1000 0.76 0.35 0.43 0.05 0.01

* exceeds the chronic risk LOC (RQ > 1.0) for non-listed and listed species.

Table 12. Mammalian dose-based chronic RQ values for proposed uses of Quizalofopp-ethyl based on a rat reproductive NOAEL of 5 mg/kg /day and mean Kenaga residues.

Mammalian Chronic Risk Quotients (Mean Kenega values) Use/App.

Method Application
Rate lbs. a.i./A

(# app / interval, days) Body Weight, g Short
Grass Tall Grass Broadleaf
Plants/Small

Insects Fruits/pods/

large insects Seeds

15 0.9 0.40 0.50 0.07 0.02

35 0.80 0.30 0.40 0.06 0.01 Sunflower 0.12

1000 0.40 0.20 0.21 0.03 0.01

15 1.30* 0.53 0.66 0.09 0.05

35 1.07* 0.50 0.60 0.19 0.02 Flax 0.17

1000 0.60 0.24 0.30 0.05 0.01

15 0.60 0.30 0.31 0.05 0.01

35 0.50 0.21 0.30 0.04 0.01 Barley and
Wheat 0.08/ 1 application

1000 0.30 0.11 0.14 0.02 <<0.01

* exceeds the chronic risk LOC (RQ > 1.0) for non-listed and listed species.

42Seedling emergence and vegetative vigor studies were classified as unacceptable, therefore RQs were not calculated for terrestrial plants.

15. RESIDUES OF QUIZALOFOP-P-ETHYL AND QUIZALOFOP ACID
DEGRADATE IN WATER AND THE TERRESTRIAL ENVIRONMENT

The acceptable aerobic soil metabolism study shows that quizalofop-p-ethyl degrades microbially with a half-life of 1 day in sandy lo am and silt loam soils. Degradation products are quizalofop acid, phenolic compounds, and CO 2 . Supplemental studies also show that quizalofop-p-ethyl is moderately mobile with K ads of 1.5-1.9 in sandy loam soil, and immobile in
silt loam soil with K ads of 16-20.

Existing data from the Environmental Fate and Effects Division (EFED) files show conflicting results between laboratory studies and field studies. The acceptable laboratory aerobic soil metabolism study shows that quizalof op-p-ethyl degrades microbially with a half-life of 1 day in sandy loam and silt loam soils. However, quizalo fop-p-ethyl was persistent in the field with half-lives of 145 and 364 days for studies conduc ted in IL and CA, respectively. The laboratory studies indicate that dissipati on occurs quickly via aerobic and anaerobic degradation, however, the field studies suggest that qui zalofop-p-ethyl is persistent in th e field. The differences may be due to differences of the microbial po pulations in the different soil media.

DRINKING WATER RESIDUE PROFILE

The Agency does not have monitoring data availa ble to perform a quantitative drinking water risk assessment for quizalofop-P ethyl at this time. A Tier II drinking water assessment prepared by the Environmental Effects and Fa te Division (EFED) is summarized below (D310868, J. Lin, 10/25/2005).

Quizalofop ethyl is rapidly c onverted to quizalofop acid, which appears to be persistent. Likely residues of quizalofop ethyl and the quizalofop acid in surface drinking water were estimated using the PRZM -EXAMS to simulate pesticide transport as a result of runoff and erosion from agricultural fields. For evaluating ground water residues, a Tier I S creening

C oncentration I n Gro und W ater (SCIGROW) model was used. Among the various uses, a scenario on dry beans at 0.1925 lb ai/A/season in th e state of Michigan wa s used to predict the "worst case" estimate of drinking water con centration (EDWCs). The EDWCs obtained by
these two models are summarized in Table 13.

Table 13. Drinking Water EDWCs for Quizalofop ethyl (ppb)

Model Used Acute Chronic Cancer

PRZM/EXAMS 5.25 1.99 1.34

SCIGROW 0.15 0.15

43New drinking and ground water assessments will be required due to proposed maximum seasonal application rates resu lting in 0.4125 lb ai/A for orname ntal trees, shade trees and pineapple. Chemical structures for quizal ofop and fenoxaprop analogs are summarized in
Table14

.

Table 14. Chemical name and structure of quiz alofop-p-ethyl and quizalofop-ethyl

Chemical structure of quizalofop acid, the degradate of concern, is not available.

Chemical name and structure of fenoxaprop -p-ethyl and fenoxaprop-ethyl

(analogs used to derive estimated toxicity val ues for non-vascular plants)

Common Name/Number Chemical Structure

Quizalofop-p-ethyl

Quizalofop-ethyl

Fenoxaprop-p-ethyl O O

O

O N

O Cl

Fenoxaprop-p OH O

O

O N

O Cl

44The following test materials are listed as quizalofop-ethyl:

INY 6202 NC 302
Lot 8002
INY 6202-15
NB 9083-86

The following test materials are listed as quizalofop-p-ethyl : IN 79376
DPX 79376

45mice, and dogs. The risk assessments reflect curr ent FQPA policies, addr ess susceptibility of infants and children, the FQPA Safety Factor, and aggregate exposures . The current risk estimates are below Agency levels of concern fo r all population subgroups as a result of dietary exposures (inclusive of food and drinking water). These risk estimat es are generally conservative and health-protective an d should not underestimate exposure a nd risk. Residential exposures to quizalofop-ethyl and quizalofop-p-et hyl are not anticipated; there are no registered residential uses. Based on the combination of low hazard (v ia dermal and inhalation routes) and exposure potentials, HED determined that occupational risk assessments were not required. No new data are required

. HED anticipates no revisions to the ri sk assessments for existing uses of quizalofop-ethyl and qu izalofop-p-ethyl.

Introduction. Quizalofop-ethyl (including its R-enantiome r, quizalofop-p-ethyl) is a systemic herbicide that is rapidly absorb ed by treated foliage and transl ocated to the roots and other growing points of the plant. Aff ected plant tissues become necr otic/chlorotic and die leaving treated plants stunted and non-comp etitive. It controls annual and perennial grasses. It can be applied using ground boom equipment and by fixe d wing aircraft as broadcast and banded applications. It has low application rates.

Products containing quizalofop-ethyl and quiza lofop-p-ethyl are currently registered. Quizalofop-ethyl is a 50/50 race mic mixture of R- and S-enantio mers. Quizalofop-p-ethyl is the purified R-enantiomer. The pesticidally active isom er is the R-enantiomer (quizalofop-p-ethyl). HED determined that the toxicological profile of the 50/50 racemic mixture (quizalofop-ethyl) and the R-enantiomer (quizalofop-p-ethyl) are simila r, and that the currently available toxicity data on quizalofop-ethyl are adequate to suppor t risk assessments reflecting uses of both quizalofop-ethyl and qu izalofop-p-ethyl.

Use Pattern and Exposure Potential. It is registered for use on a variety of food/feed use agricultural crops and no n-agricultural crops. Food uses incl ude: grains, legumes, cotton, garlic, mint, sugar beets, sunflower, pineapple, and Chinese cabbage. Several crops are grown for seed only, including: carrot, alfalfa, beets, Swiss ch ard, radish, onion, and spinach. Non-agricultural crops include: cottonwood and poplar plantations and uncultivated areas, such as fencerows and roadsides. No lawn, sidewalk, driveway, tenni s court, or similar public areas have been registered as use sites. Based on its registered us e patterns, there is the potential for dietary (via food and water) and occupationa l exposures to quizalofop-et hyl and quizalofop-p-ethyl. Homeowner exposures via reside ntial uses are not expected.

Hazard Characterization. Quizalofop-ethyl and quizalofop-p-ethyl are considered to be toxicologically similar. HED based this determin ation on a comparison of toxicity data submitted for the registration of quizalofop-ethyl and a s ubset of toxicity data for quizalofop-p-ethyl. Specifically, toxicity data available for quizalof op-p-ethyl included: an ac ute oral study in the rat, 90-day subchronic feeding st udies in the rat and mouse, and three mutagenicity studies.
Results from these studies were similar to results obtained from the same studies using

47quizalofop-ethyl. Conclusions rega rding the toxicity of quizalo fop-ethyl are applicable to quizalofop-p-ethyl.

The toxicity database for quizal ofop-ethyl was reviewed in 19 94 and reevaluated in October 1997 to specifically assess sensi tivity in infants and children unde r FQPA. The toxicity database was found to be substantially complete and ad equate to assess ri sk under FQPA. HED has determined that the currently av ailable toxicity data on quizalof op-ethyl are adequate to support risk assessments reflecting uses of bot h quizalofop-ethyl an d quizalofop-p-ethyl. No additional toxicity data for either quizalofop-ethyl or qui zalofop-p-ethyl are required. No toxicity studies involving human subjects were relied upon in an y of the risk assessments conducted for quizalofop-ethyl or qu izalofop-p-ethyl.

Toxicity endpoints selected fo r risk assessment in 1994 were confirmed in the 1997 reevaluation. The FQPA Safety Factor was reduced to 1X a nd the current risk assessments reflect this reduction. HED believes the FQPA Safety Factor reflected in the current risk assessment for quizalofop-ethyl is supported by the available toxicity and exposure information on quizalofopethyl and that the risk assessments are protective of human health.

The toxicity database includes acceptable de velopmental studies in rats and rabbits, reproduction/fertility studies in ra ts, subchronic studies in rats a nd dogs, chronic studies in rats and dogs, carcinogenic studies in rats and mice, mutagenicity screens, and a 28-day dermal toxicity study in rats, as well as inform ation on the metabolism and pharmacokinetics of quizalofop-ethyl. A search of the open literatur e was conducted for toxicity studies involving quizalofop-ethyl using NIH’s PubMe d, SCRIUS, Science Direct, and a full text medical journals
search. No in vivo toxicity testing studies or other inform ation that would be relevant to HED’s
human health risk assessments were found from 1995 to the present. NCEA’s IRIS shows no activity on quizalofop-ethyl since the late 1980s. No new toxicity data have been submitted.

The liver is the primary target organ for repeat ed doses of quizalofop-ethy l. Effects on the liver
manifested as increased liver we ights and histological changes in the liver. Liver effects and decreases in body weight gain and food consumpti on as a result of repeat dosing were seen in subchronic and chronic/carcinogen icity studies in rats, mice, a nd dogs. Metabolism and excretion occur quickly in the rat. No toxic effects attri butable to a single oral dose of quizalofop-ethyl
were identified.

It is classified in Toxicity Ca tegory III (low acute toxicity) fo r dermal, inhalation, eye and skin irritation. No localized or systemic effects were associated with a dermal dose of up to 2000 mg/kg/day. As a result of this finding and a lack of developmen tal effects, no dermal toxicity endpoint was selected. In addi tion to quizalofop-ethyl’s clas sification as a Category IV inhalation toxicant, its use pattern indicates lo w single and seasonal maxi mum application rates, its vapor pressure is 1 x 10 -4 kPa (meaning it is considered a non-volatile chemical for outdoor uses), and risk estimates (MOEs) for inhalati on exposures are approxima tely 1000 or greater. As a result of these findings, no inha lation toxicity endpoint was sele cted. Based on the lack of dermal effects and negligible i nhalation exposures, occupational risk assessments were neither required nor conducted.

48Quizalofop-ethyl does not appear to be a ne urotoxic chemical; there were no signs of neurotoxicity in the available toxicity studies for quizalofop-et hyl. Specifically, treatmentrelated effects on brain weight or histopathology (non-perfused) of the nervous system were not observed in any study, there was no evidence of de velopmental anomalies in the nervous system of the fetus at maternal doses up to 300 mg/kg/day in rats and 60 mg/kg/day in rabbits, and there was no evidence of neurotoxicity on the functional development of offspring during the postnatal portion of the developmental toxicity study in rats.

No special sensitivity was seen in rats and rabbits in utero as a result of exposure to quizalofopethyl. Exposure to quizalofop-ethyl at doses causing liver and body wei ght effects in adult
animals did not lead to effects in fetuses. Exposure to quizalofop-ethyl at doses causing body weight effects in adult animals resulted in similar effects in offspring. As a result, the FQPA Safety Factor was reduced to 1X.

Califrornia lists quizalofop-ethyl as a reproductive toxicant. Quizal ofop-ethyl was first listed in 1994 under California’s Proposition 65: the Safe Drinking Water and Toxics Enforcement Act and the Toxics Release Inventory (TRI). The listing was based on a 26-week feeding study in dogs conducted in 1982 in which 2 of 6 male dogs showed atrophy of some seminiferous tubules at the highest dose tested (10 mg/kg/day). The effect was not so severe as to cause disturbance of spermatogenesis. These effects could not be repeated in a follow-up study conducted over a 52- week period in 1985 in which dogs were fed the same doses as in the 1982 study. There were no treatment-related effects in the follow-up study.

Quizalofop-ethyl is currently classified as a “G roup D “ carcinogen, i.e., not classifiable as to human carcinogenicity.

Given the toxicological and chemical similariti es between quizalofop-ethy l and the R-enantiomer (quizalofop-p-ethyl), the two co mpounds will be referred to as quizalofop in the remainder of
this document.

To assess risk associated with chronic dietary (oral) exposures to quizalofop, a chronic reference dose (cRfD) of 0.009 mg/kg/day has been establis hed. The cRfD was selected from a combined chronic/carcinogenicity toxicity study in rats in which no eff ects were noted at 0.9 mg/kg/day
and anemia and liver effects were noted at 4 mg/kg/day. The cRfD is based on the lowest and most conservative endpoint in th e toxicity database. The cRfD re flects a 100-fold safety factor for inter- and intra-species variability. Because the FQPA safety factor was reduced to 1X, the chronic population adjusted dose (c PAD) is equivalent to the cRfD . The cRfD selected to assess risks from chronic dietary exposur es to quizalofop is protective of the reproductive effects seen in 26-week study in the dog. Toxic endpoints for ac ute dietary and occupational risk assessments
have not been selected for the reasons discussed above.

Dietary Exposure and Risk Estimates . Dietary risk estimates for exposures to quizalofop in food and drinking water are below levels of conc ern. They reflect current policy and practice. The tolerance expression and residu es of concern for risk assessment for registered uses need not be revised. The dietary risk assessments in clude all permanent to lerances (Section 3 registrations). There are adequate residue data reflecting the use of all existing formulations on

49representative commodities; the dietary exposure database is complete. No new residue data have been submitted. There are no issues concerning residue chemistry and no new data are required.

An acute dietary risk assessment was not conducted because no toxic endpoint attributable to a single oral dose was identified in the toxicity database. Chronic dietary risk for the general population was estimated to be 11% of the chr onic Population Adjusted Dose (cPAD) and 29% of the cPAD for children 1 to 2 years old. Chr onic dietary risk estimates are conservative and unrefined. They reflect tolera nce level residues and 100% crop-tr eated values were assumed for all commodities. Drinking water exposures were a ssessed for a scenario for dry peas in Michigan using direct incorporatio n of estimated environmental concen trations (EECs) into the chronic dietary analyses. The drinking water assessment re flects current policy and practice. The current dietary risk assessments provide conservative, health protective , high-end estimates of exposure to quizalofop residues in food and water. The current dietary risk assessments are not expected to
underestimate risks.

Residential Exposure and Risk Estimates . Quizalofop-containing pr oducts are not registered for use in/on residential or public recreational sites; there are no re gistered lawn or garden uses.
No residential risk assessments were conducted.

Aggregate Risk Estimates . Risk estimates for aggregate exposures to quizalofop are below levels of concern. Average exposures in food a nd drinking water were combined and compared to the appropriate endpoint to es timate chronic aggregate risk.

Occupational Exposure and Risk Estimates . As stated previously, occupational risk assessments are not required and have not been conducted for quizalofop. Qu izalofop is not toxic via the dermal route; therefore, no dermal endpoi nt was selected. Quizalofop is a Category III Inhalation Toxicant indicating low toxicity by the inhalation route, it is not volatile, and it has low use rates. All of these factors indicate that use of quizalofop will not lead to inhalation exposures of concern. To support this qualitati ve assessment, HED has estimated risks from inhalation exposures for workers applying and handling quizalofop products for a number of high acreage crops using a screening-level analys is. This screening-level analysis uses maximum use rates, maximum acreage, and the cRfD to estimate inhalation risks. Risk estimates based on inhalation exposures of pesticide handlers (m ixers, loaders, applicators) for barley, flax, sunflower, wheat, cotton, pineapple, and non-cr op areas are all below HE D’s level concern. The Margins of Exposure (MOEs) resulting from th is screening assessment range from >500 to 160,000 are not of concern as they are well a bove 100. In summary, based on quizalofop’s low toxicity via the dermal and inhalation routes, its physical/chemical properties, low exposure potential, and a screening-level analysis indicating that there are no inhalation exposures of concern, occupational risk assessments were not conducted. A 12-hour Restricted Reentry Interval (REI) has been establis hed and is reflected on the labels of all registered products.

Public Health and Incident Reports . Very few incidents of poisoning associated with exposures to quizalofop have been reported. This finding supports HED’s risk assessment, which indicates that both exposure to and toxicity of quizal ofop are low. Since 1988 when it was first registered, a total of 18 reports of poisoning in cidents have been reported. The Poison Control

50Center (PCC), reporting from 1993 to 2005, cites 10 incidents. All individuals affected were adults; the effects reported were headache, eye a nd throat irritation. OPP’s Incident Data System (IDS) reports 8 incidents. The incidents are associated with a variety of symptoms including rashes, cramping, swelling, diarrhea, nausea, dizz iness, lethargy, and hypothermia. None of these effects is consistent with the toxicity da tabase for quizalofop. Quizalofop is not an acutely toxic chemical, there is no indica tion of neurotoxicity, and the majo rity of toxic effects seen in the animal studies were systemic effects that were the result of repeated dosing, such as liver and body weight effects. The National Institutes of O ccupational Safety and Health’s Sentinel Event Notification System (NIOSH SENSOR) reporte d 5899 cases of poisoning incidents between 1998 and 2003. None of these reported incide nts was associated with quizalofop.

Cumulative Risk Assessments. The Agency has not determined whether quizalofop shares a common mechanism of toxicity with other ch emical substances, and whether a cumulative assessment is warranted. The following reference contains information regarding determination
of common mechanisms of toxic ity: “Guidance for Identifying Pesticide Chemicals and Other
Substances that have a Common Mechanism of Toxicity” (January 29, 1999). To date, the Agency has assessed the potential for a common mechanism of toxicity for four groups of chemicals: organophosphates, N-methyl carbamates, S-triazines, and chloroacetanilides. If quizalofop is determined to share a common mechan ism of toxicity with other substances, then methods for aggregating exposures and risks will be developed. Until quizalofop is scheduled for
a common mechanism determination and a d ecision is made, the Agency would not a priori assume a common mechanism of toxicity ex ists for quizalofop and other substances.

Data Requirements . No new data are required.

Tolerances and International Harmonization . Permanent and time-limited tolerances for quizalofop from the most recent CFR are provided in the table below along with international
tolerances. The Codex Alimentarius Commission has not established Maximum Residue Limits (MRLs) for residues of quizalofop in/on various raw agricultural and processed commodities.
Canada and Mexico have established MRLs for quizalofop. US tolerances and MRLs on raw agricultural commodities from these countries do not appear to have been harmonized. However, meat, milk, poultry and egg tolera nces with the exception of m ilk, fat have been harmonized
between Canada and the US. The residue definitions appear to be the same for raw agricultural commodities, but slightly different for animal commodities.

51

## Quizalofop

US Canada Mexico Codex

Residue Definition:
Combined residues of the herbicide quizalofop (2-[4-(6-chloroquinoxalin-2-yl oxy)phenoxy]propanoic acid) and quizalofop ethyl (ethyl-2-[4-(6-chloroquinoxalin-2-yl oxy)phenoxy]propanoate), all expressed as quizalofop ethyl

40CFR.180.441 ethyl (RS) 2-[4-(6- chloroquinoxalin-2-yloxy) phenoxy] propionate, including the
acid metabolites of (RS)2-[4-(6- chloroquinoxalin-2-yloxy) phenoxy] propanoic acid, allexpressed as quizalofopethyl quizalofop none

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg) Bean, dry 0.4 0.15 1

Bean, succulent 0.25
Beet, sugar, roots 0.1
Beet, sugar, tops 0.5
Cowpea, forage 3.0
Cowpea, hay 3.0
Pea, dry 0.25
Pea, field, hay 3.0

Pea, field, vines 3.0

Pea, succulent 0.3 0.05 (dry or succulent not specified)

Potato
- 0.3
Soybean flour 0.5
Soybean, hulls 0.02
Soybean, meal 0.5
Soybean, soapstock 1.0
Soybean 0.05 0.05 0.05

Residue Definition:

Combined residues of the herbicidequizalofop (2-[4-(6-chloroquinoxalin2-yl oxy)phenoxy]propanoic acid), quizalop-ethyl (ethyl-2-[4-(6- chloroquinoxalin-2-yl oxy)phenoxy]propanoate), and quizalofop-methyl (methyl 2-[4-(6-chloroquinoxalin-2-yloxy)phenoxy]propanoate, all expressed as quizalofop ethyl As above As above none

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg) 0.05 0.05

52

### US Canada Mexico Codex

Cattle, meat 0.02 0.02
Cattle, meat bypro ducts 0.05 0.05
Egg 0.02 0.02

Goat, fat 0.05 0.05

Goat, meat 0.02 0.02
Goat, meat byproducts 0.05 0.05
Hog, fat 0.05 0.05
Hog, meat 0.02 0.02
Hog, meat byproducts 0.05 0.05

Horse, fat 0.05 0.05
Horse, meat 0.02 0.02
Horse, meat byproducts 0.05 0.05

Milk 0.01 0.01 Milk, fat 0.25 0.05 Poultry, fat 0.05 0.05 Poultry, meat 0.02 0.02 Poultry, meat byproducts 0.05 0.05 Sheep, fat 0.05 0.05 Sheep, meat 0.02 0.02 Sheep, meat byproducts 0.05 0.05

Residue Definition:

Combined residues of the herbicide quizalofop-p ethyl ester [ethyl ( R )-(2-[4- ((6-chloroquinoxalin-2- yl)oxy)phenoxy)propanoate], and its acid metabolite quizalofop-p [ R -(2-(4-((6- quinoxalin-2-yl)oxy)phenoxy)propanoic acid], and the S enantiomers of both the ester and the acid, all expressed as quizalofop-p-ethyl ester As above As above none

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg) Barley, grain 0.05
Barley, hay 0.05
Barley, straw 0.05
Beet, sugar, molasses 0.2

Canola, meal 1.5

Canola, seed 1.0 0.05

Cotton, undelinted seed 0.1 0.05

Flax, seed 0.05 0.05

Lentil, seed 0.05 0.05
Peppermint, tops 2.0
Spearmint, tops 2.0

Sunflower, seed 1.9
Wheat, forage 0.05
Wheat, grain 0.05
Wheat, hay 0.05

Wheat, straw 0.05

53

### US Canada Mexico Codex

Beet, sugar root (time limited 06/14/1999) 0.1 0.2 (top or bottom not specified) Beet, sugar, tops (time limited 06/14/1999) 0.5

Vegetable, foliage of legume, except soybean, subgroup 7A (time limited 06/14/1999) 3.0

Vegetable, legume, group 6 (time limited 06/14/1999) 0.25

Pineapple (Regional registration) 0.1

1 Interim Marketing Authorization, including adzuki beans, dry beans, dry lima beans, kidney beans, mung beans, navy beans, and pinto beans.



## Considerations

In preparation of this problem formulati on document for quizalofop-ethyl in support of registration review the follo wing has been considered:

• Search for and review of the most current human health risk assessments, including occupational/residential and dietary asse ssments conducted for new uses, Section 18 Emergency Exemptions, and Special Local N eeds (24Cs) using internal Lotus Notes
databases

• Review of the most recent decisions regard ing hazard characterization, the adequacy and completeness of the toxicity database, the FQ PA Safety Factor neur otoxicity, thyroid and immune system effects, and cancer issues to en sure their reflection in the most recent risk

assessments

• Search of the OPPIN database to identify data submitted that have not been reviewed or
included in the most current risk assessments

• Review E Jackets to clarify the status of a use

• Review of the most current labels to ensure all current registrations have been included in
the most recent risk assessments

• Conduct a search of the gene ral literature for information on quizalofop-ethyl not captured in current risk assessments

• Review of labeled uses a nd use information from BEAD

• Review of tolerances listed in Part 140 of the Code of Fe deral Regulations (CFR) Section

180.441

• Review of Codex Alimentarius and Canadian and Mexican MRLs to identify tolerance
harmonization issues

• Determine if most recent risk assessments reflect current policies

• Review of poisoning incidents

54Reference Memoranda:

Burnam, William, May 5, 1995, Accession No. 412- 04-0141, Quizalofop-p Ethyl Ester’s Cancer
Classification.

Donald, J., Reproductive and Cancer Hazard Assessment Section (RCHAS), Office of Environmental Health hazard Assessment (O EHHA), California Environmental Protection Agency (CAL/EPA), September 1999, “Evidence on Developmental and Reproductive Toxicity of Quizalofop-Ethyl”, DRAFT.

Hawkins, M., D342226, July 31, 2007, “Review of Quizalofop Incident Reports”.

HED SOP 2002.01 Standard Operating Procedur e – Waiver Criteria for Multiple-Exposure Inhalation Toxicity Studies. August 15, 2002.

Johnson, H., D306061, August 2, 2004, “ARIA Risk Assessment: Quizalofop-ethyl Human
Health Risk Assessment for Toleranc e Renewal on Expired Tolerances”.

Knizner, S., D236729 & D243535, February 25, 1998, “PP#5F4545 and PP#6E4652 Quizalofopp-ethyl: Petitions for Tolera nces for Canola and Mint”.

Oonnithan, S., D310869, August 10, 2006, “Quizalofop- p-ethyl: Human Health Risk Assessment for New Uses on Barley, Flax, Sunflower, and Wheat”.

Oonnithan, S., D266205, August 10, 2006, Quizalof op-p-ethyl: “Occupational Risk Assessment for the Proposed Uses on Barley, Flax, Sunflower, and Wheat”.

Personal communication (letter) from Robert J. Taylor, PM, Registration Division, OPP to Marie M. Chubb, du Pont de Nemours & Company RE : toxic profiles of quizalofop-ethyl and quizalofop-p-ethyl (undated).

Quest, J., TXR 0052709, February 6, 1987, “Peer Review of Assure”.

Rowland, J., TXR 012373, October 24, 1997, “Q uizalofop-ethyl: Report of the Hazard Identification Assessment Review Committee (HIARC)”.

55

### IV. Glossary of Terms and Abbreviations

ai Active Ingredient AR Anticipated Residue

CFR Code of Federal Regulations cPAD Chronic Population Adjusted Dose

CSF Confidential Statement of Formula CSFII USDA Continuing Surveys for Food Intake by Individuals
DCI Data Call-In DEEM Dietary Exposure Evaluation Model DFR Dislodgeable Foliar Residue DNT Developmental Neurotoxicity DWLOC Drinking Water Level of Comparison
EC Emulsifiable Concentrate Formulation EDWC Estimated Drinking Water Concentration

EEC Estimated Environmental Concentration EPA Environmental Protection Agency
EUP End-Use Product FDA Food and Drug Administration FIFRA Federal Insecticide, Fungicide, and Rodenticide Act FFDCA Federal Food, Drug, and Cosmetic Act FQPA Food Quality Protection Act FOB Functional Observation Battery GENEEC Tier I Surface Water Computer Model
IR Index Reservoir
LC 50 Median Lethal Concentration. A statistically derived concentration of a substance that can be expected to cause death in 50% of test animals. It is usually expressed as the weight of substance per weight or volume of water, air or feed, e.g., mg/l, mg/kg or ppm.

LD 50 Median Lethal Dose. A statistically derive d single dose that can be expected to cause
death in 50% of the test animals when admini stered by the route i ndicated (oral, dermal, inhalation). It is expressed as a weight of substance per unit weight of animal, e.g., mg/kg.
LOC Level of Concern
LOAEL Lowest Observed Adverse Effect Level μg/g Micrograms Per Gram μg/L Micrograms Per Liter mg/kg/day Milligram Per Kilogram Per Day mg/L Milligrams Per Liter MOE Margin of Exposure

MRID Master Record Identifi cation (number). EPA's system of recording and tracking
submitted studies. MUP Manufacturing-Use Product

NA Not Applicable NAWQA USGS National Ambient Water Quality Assessment NPDES National Pollutant Discharge Elimination System

NR Not Required
NOAEL No Observed Adverse Effect Level

OPP EPA Office of Pesticide Programs OPPTS EPA Office of Prevention, Pesticides and Toxic Substances PAD Population Adjusted Dose PCA Percent Crop Area

PDP USDA Pesticide Data Program PHED Pesticide Handler's Exposure Data
PHI Preharvest Interval

56ppb Parts Per Billion
PPE Personal Protective Equipment

ppm Parts Per Million PRZM/EXAMS Tier II Surface Water Computer Model Q 1 * The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer Risk Model RAC Raw Agriculture Commodity RED Reregistration Eligibility Decision

REI Restricted Entry Interval
RfD Reference Dose RQ Risk Quotient SCI-GROW Tier I Ground Water Computer Model
SAP Science Advisory Panel SF Safety Factor
SLN Special Local Need (Registra tions Under Section 24©) of FIFRA) TGAI Technical Grade Active Ingredient USDA United States Department of Agriculture UF Uncertainty Factor
WPS Worker Protection Standard

57