Docket Number: EPA-HQ-EPA- OPP-2007-1135 

www.regulations.gov 

Quinclorac Summary Document 

Registration Review: Initial Docket 

December 2007 

Case # 7222
Docket Number: EPA-HQ-EPA- OPP-2007-1135 

www.regulations.gov 

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Quinclorac Summary Document 

Registration Review: Initial Docket 

December 2007 

 

Approved By: 

 

___________________ 

 Steven Bradbury, Ph.D. 

 Director, Special Review and 

 Reregistration Division
Docket Number: EPA-HQ-EPA- OPP-2007-1135 

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TABLE OF CONTENTS 

 Page # 

I. Preliminary Work Plan (PWP) 4 

II. Fact Sheet 9 

III. Glossary of Terms and Abbreviations 14 

IV. Ecological Risk Assessment Problem Formulation 16 

V. Human Health Effects Scoping Document 56 
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I. Preliminary Work Plan - Quinclorac 

Introduction:

The Food Quality Protection Act of 1996 mandated a new program: registration review. All 

pesticides distributed or sold in the United States generally must be registered by the U.S. 

Environmental Protection Agency (USEPA; EPA; The Agency), based on scientific data 

showing that they will not cause unreasonable risks to human health, workers, or the 

environment when used as directed on product labeling. The new registration review program is 

intended to make sure that, as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no unreasonable 

adverse effects. Changes in science, public policy, and pesticide use practices will occur over 

time. Through the new registration review program, the Agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used safely. 

Information on this program is provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

The Agency has begun to implement the new registration review program, and will review each 

registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard 

for registration. The public phase of registration review begins when the initial docket is opened 

for each case. The docket is the Agency’s opportunity to state what it knows about the pesticide 

and what additional risk analyses and data or information it believes are needed to make a 

registration review decision. After reviewing and responding to comments and data received in 

the docket during this initial comment period, the Agency will develop and commit to a final 

work plan and schedule for the registration review of quinclorac. 

Quinclorac is a systemic pre- and post- emergent herbicide to control broadleaf and grass weeds. 

It is registered for use on agricultural crops as well as on turf in residential and commercial areas. 

Anticipated Risk Assessment and Data Needs:

The Agency will conduct a comprehensive ecological risk assessment, including an endangered 

species assessment for quinclorac. The Agency will also perform an occupational risk 

assessment, a drinking water assessment, a residential handler assessment, and an aggregate 

assessment. 

Ecological Risk: 

• The most recent comprehensive ecological risk assessment for registered uses was 

conducted on wheat and sorghum in 1999. The Agency has not conducted a risk 

assessment that supports a complete endangered species determination. Please refer to 

Section IV, Ecological Risk Assessment Problem Formulation, for a detailed discussion 

of the anticipated risk assessment needs. 
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• The Agency anticipates needing the following data in order to conduct a complete 

ecological risk assessment, including an endangered species assessment, for all uses: 

o (GLN 850.1010) Aquatic invertebrate acute toxicity test, freshwater daphnids 

o (GLN 850.1300) Daphnid chronic toxicity test 

o (GLN 835.7100) Ground water monitoring 

• The planned ecological risk assessment will allow the Agency to determine if 

quinclorac’s use has "no effect" on federally listed threatened or endangered species 

(listed species) or their designated critical habitat. If the screening level assessment 

indicates that quinclorac "may affect" a listed species or its designated critical habitat, the 

assessment will be refined. The refined assessment will allow the Agency to determine 

whether use of quinclorac is “likely to adversely affect” the species or critical habitat or 

"not likely to adversely affect" the species or critical habitat. When an assessment 

concludes that a pesticide's use "may affect" a listed species or its designated 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 toxicological endpoint selections are adequate; however, the toxicology database for 

quinclorac is incomplete at this time. A 90-day inhalation toxicity study in the rat is 

required to assess inhalation exposure from spray uses (GLN 870.3465). 

• The residue chemistry database is complete. However, newly submitted aspirated grain 

fraction studies on wheat and sorghum will have to be reviewed, and livestock tolerances 

may need to be revised based on this review. 

• The dietary (food alone) assessment is adequate. However, a new drinking water 

assessment will be conducted; therefore, an aggregate assessment will be needed. 

• The residential post application exposure assessment is adequate, therefore no residential 

post application assessment is needed. However, no residential handler risks were 

assessed; therefore, a new residential handler assessment is needed. 

• No occupational risk assessments have been conducted. Occupational risk assessments 

will be needed for all scenarios. 

• Please refer to Section V of this document, Human Health Effects Scoping Document, for 

a detailed discussion of the anticipated risk assessment needs for human health. 

 
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Timeline:

EPA has created the following estimated timeline for the completion of the quinclorac 

registration review. The Agency may conduct the occupational assessment much earlier in the 

process, allowing mitigation (if necessary) to occur well before completion of the final decision. 

Registration Review for quinclorac – 

Projected Registration Review Timeline 

Activities Estimated 

Month/Year 

Phase 1: Opening the docket 

Open Public Comment Period for Quinclorac Docket 2007 – Dec. 

Close Public Comment Period 2008 – Mar. 

Phase 2: Case Development 

Develop Final Work Plan (FWP) 2008 – Apr.- Jun. 

Issue DCI 2009 – Jan - Mar. 

Data Submission 2013 – Jan - Mar. 

Open Public Comment Period for Preliminary Risk Assessments 2014 – Jul. – Sept. 

Close Public Comment Period 2014 - Oct. – Dec. 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision 2015 – Jan. – Mar. 

Close Public Comment Period 2015 – Apr. – Jun. 

Final Decision and Begin Post-Decision Follow-up 2015 – Jul. Sept. 

Total (years) 8 

Guidance for Commenters:

The public is invited to comment on EPA’s preliminary registration review work plan and 

rationale. The Agency will carefully consider all comments as well as any additional 

information or data provided prior to issuing a final work plan for the quinclorac case. 

• Through the registration review process, the Agency intends to solicit information on 

trade irritants and, to the extent feasible, take steps toward facilitating irritant resolution. 

Growers and other stakeholders are asked to comment on any trade irritant issues 

resulting from lack of Maximum Residue Limits (MRLs) or disparities between U.S. 

tolerances and MRLs in key export markets, providing as much specificity as possible 

regarding the nature of the concern. Please see section V of this document, Quinclorac, 

Human Risk Problem Formulation Document in Support of Registration Review, for a 

listing of the differences among the U.S., Canada, Codex, and Mexico tolerances. 
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• Quinclorac is not identified as a cause of impairment 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 OPP’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 quantitatively or qualitatively in pesticide risk assessments. 

• EPA seeks to achieve environmental justice, the fair treatment and meaningful 

involvement of all people, regardless of race, color, national origin, or income, in 

the development, 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 their location, cultural practices, or other factors, may have atypical, 

unusually high exposure to quinclorac compared to the general population. 

Please comment if you are aware of any sub-populations that may have atypical, 

unusually high exposure compared to the general population. 

Stakeholders are also specifically asked to provide information and data in the following areas. 

• There is specific information that will assist the Agency in refining the ecological risk 

assessment, including any species-specific effects determinations. The Agency is 

interested in obtaining the following information regarding the use of quinclorac: 

1. confirmation on the following label information 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates 

e. frequency of application, application intervals, and maximum number of 

applications per season 

f. geographic limitations on use 

2. use or potential use distribution (e.g., acreage and geographical distribution of 

relevant crops) 

3. use history 

4. median and 90th percentile reported use rates (lbs ai/acre) from usage data – 

national, state, and county 

5. application timing (date of first application and application intervals) by crop – 

national, state, and county 

6. sub-county crop location data 
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7. usage/use information for non-agricultural uses (e.g., forestry, residential, rights-ofway) 

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

a. maximum reported use rate (lbs ai/acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county 

e. the year the pesticide was last used 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 already reported to the Agency 

12. monitoring data 

Next Steps:

After the comment period closes, the Agency will prepare a Final Work Plan for this pesticide. 
Docket Number: EPA-HQ-EPA- OPP-2007-1135 

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II. FACT SHEET 

 

Background Information:

• Quinclorac Registration Review case number: 7222 

• Quinclorac is a systemic pre- and post- emergent herbicide to control broadleaf and grass 

weeds on rice, sorghum, wheat, residential lawns, ornamentals and turf grass. 

• Quinclorac PC code: 128974; CAS #: 84087-01-4 

• Technical Registrant: Albaugh Inc. 

• First approved for use in 1992, therefore not subject to reregistration. 

• Tolerance Reassessment was released on March 26, 1999 through publication in the 

Federal Register (64 FR 14626). 

• Special Review and Reregistration Division (SRRD), Chemical Review Manager (CRM): 

Joy Schnackenbeck: schnackenbeck.joy@epa.gov 

• Registration Division (RD) Contacts: 

Jim Tompkins: tompkins.jim@epa.gov; Hope Johnson: johnson.hope@epa.gov 

• 34 total active products are registered; 1 technical product, 3 manufacturing use products, 

26 end use products, and 4 special local needs permits (SLN; 24c). 

• Quinclorac is sold in several different formulations including water dispersible granules, 

emulsifiable concentrate and wettable powder. 

• Quinclorac can be applied through aerial equipment, tank spray, boom sprayer, hand held 

sprayer, and backpack sprayer. 

Use & Usage Information: (For additional details, please refer to the BEAD Appendix A 

document in the quinclorac docket.)

• Quinclorac is a quinoline carboxylic acid, whose mechanism of herbicidal action is 

generally mimicry of the plant growth hormone, auxin. 

• Quinclorac is used on less than 2.5 % of the total crop treated for corn, summer fallow, 

sorghum and wheat. On average, it is used on 30% of the total crop treated for rice. 

• Approximately 313,000 pounds of quinclorac are used annually. 

Recent Actions:

• A Rule for quinclorac was issued on 10/28/2007 (72 FR 55068) which established 

tolerances for residues in or on imported barley grain. BASF Corporation requested this 

tolerance under the Federal Food, Drug, and Cosmetic Act (FFDCA). 

• A Rule for quinclorac was issued on 3/26/1999 (64 FR 14626), which established FQPA 

tolerances for residues on wheat and sorghum. This Rule also included the tolerance 

reassessment for rice, sorghum, wheat, residential lawns, ornamentals and turf grass. 
Docket Number: EPA-HQ-EPA- OPP-2007-1135 

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Ecological Risk Assessment Status: 

Please refer to Section IV of this document, Ecological Risk Assessment Problem Formulation 

for quinclorac registration review, for a detailed discussion of the anticipated ecological risk 

assessment needs. Below is a summary of the findings: 

• The Agency will need to conduct new assessments for all registered uses because some 

uses and application type scenarios were not assessed for ecological risk and did not 

include current terrestrial and aquatic models. 

• The Agency has some freshwater invertebrate data which indicates low risk for aquatic 

animals, however there are some unusual results with these studies, which were 

completed with a formulated product. Therefore, the Agency is requiring freshwater 

invertebrate tests with the technical, and will use these tests to estimate risks to estuarine 

animals. 

• No acute or chronic risk exceedences of the Agency’s level of concern are anticipated for 

aquatic fish or invertebrates. However, uncertainty exists for acute and chronic risks to 

estuarine marine invertebrates until further data is submitted. Chronic risks to estuarine 

marine fish will be estimated from acute to chronic ratios. 

• Before the risk assessments are developed for public comment, the Agency will 

ensure that all currently registered uses of quinclorac have an endangered species 

assessment completed. The ecological risk assessment will allow the Agency to 

determine whether quinclorac use has "no effect" or "may affect" federally listed 

threatened or endangered species (listed species) or their designated critical 

habitat. If the assessment concludes that a pesticide's use "may affect" a listed 

species or its designated 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 Assessment Status:

Please refer to Section V of this document, Human Health Effects Scoping Document, for a 

detailed discussion of the anticipated risk assessment needs for human health. A summary 

follows: 

Dietary (Food and Water): 

• The residue chemistry database is complete with the newly submitted aspirated grain 

fraction (AGF) studies. A review of the AGF studies are needed, and livestock tolerances 

may need to be revised based on this review. 

• The dietary exposure assessment is up-to-date, and no further dietary assessments are 

needed. There are no risks of concern even with a very conservative assessment. 

• A drinking water assessment is needed.
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Residential: 

• The post application exposure assessments are adequate. 

• No residential handler assessment has been conducted; therefore, a residential handler 

assessment is needed for the registration review of quinclorac. 

Occupational: 

• No occupational assessments have been conducted for quinclorac. A new occupational 

assessment is required for the registration review once the inhalation endpoint is selected. 

Aggregate: 

• Once the drinking water assessment is completed, the Agency will conduct an aggregate 

assessment.

Incident Reports:

• The search of the National Poison Control Center System (NPCS) showed only a 

total of five incidents related to quinclorac in the 13-year span of data collected and only 

two cases were reported in OPP’s Incident Data System (IDS) from 1999 to the 

present. In addition, there were no cases reported in the National Institute of 

Occupational Safety and Health Sentinel Event Notification System for 

Occupational Risks (NIOSH/SENSOR) database involving quinclorac. A more 

detailed summary is provided in a separate document in this docket.

Tolerances: 

• US tolerances are listed under 40 CFR 180.463. A table listing the differences between 

current US tolerances as compared to Codex, Canada, and Mexico appears in section V 

of this document, Human Health Effects Scoping Document.

Data Call-In Status:

• There are no current data call-ins. 

Labels: 

• A list of registration numbers may be found in the quinclorac docket and the labels can 

then be obtained from the Pesticide Product Label System (PPLS) website: 

http://oaspub.epa.gov/pestlabl/ppls.home. 

Registration # Product Name Company Name 

Percent 

Active 

Ingredient

228-423 

DQD SELECTIVE 

HERBICIDE 

NUFARM 

AMERICAS INC. 7.91
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Registration # Product Name Company Name 

Percent 

Active 

Ingredient

228-531 

NUP 12D02 

HERBICIDE 

NUFARM 

AMERICAS INC. 8.25

239-2689 

LAWN 

CRABGRASS AND 

WEED KILLER 

THE ORTHO 

BUSINESS GROUP 0.1

538-296 

TURF BUILDER 

WITH WEED 

CONTROL III 

SCOTTS 

COMPANY, THE 0.52

1381-209 

QUINCLORAC 75 

DF 

WINFIELD 

SOLUTIONS, LLC 75

2217-885 

EH-1426 

HERBICIDE 

PBI/GORDON 

CORP 3.49

2217-886 

EH-1427 

HERBICIDE 

PBI/GORDON 

CORP 5.69

2217-887 

EH-1428 

HERBICIDE 

PBI/GORDON 

CORP 0.121

2217-888 

EH-1425 

HERBICIDE 

PBI/GORDON 

CORP 8.38

2217-894 

EH-1432 

HERBICIDE 

PBI/GORDON 

CORP 1.61

2217-896 

EH-1437 

HERBICIDE 

PBI/GORDON 

CORP 2.13

2217-901 

EH-1434 

HERBICIDE 

PBI/GORDON 

CORP 5.65

2217-906 

EH-1449 

HERBICIDE 

PBI/GORDON 

CORP 0.104

7969-93 FACET 50 WP 

BASF 

CORPORATION 50

7969-109 

QUINCLORAC 

MANUFACTURING 

USE PRODUCT 

BASF 

CORPORATION 98

7969-113 

FACET 75 DF 

HERBICIDE 

BASF 

CORPORATION 75

7969-130 

DRIVE 75 DF 

HERBICIDE 

BASF 

CORPORATION 75
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Registration # Product Name Company Name 

Percent 

Active 

Ingredient

7969-152 

PARAMOUNT BW 

HERBICIDE 

BASF 

CORPORATION 15

7969-158 

FACET GR 

HERBICIDE 46 

BASF 

CORPORATION 1.5

7969-172 

DRIVE 75 

MANUFACTURERS 

CONCENTRATE 

BASF 

CORPORATION 75

7969-222 

CLEARPATH 

HERBICIDE 

BASF 

CORPORATION 61.98

34704-920 

QUINCLORAC 

75DF HERBICIDE 

LOVELAND 

PRODUCTS, INC. 75

42750-85 

QUINCLORAC 

TECHNICAL ALBAUGH INC 99

42750-88 

QUINCLORAC 

75DF AG ALBAUGH INC 75

42750-90 

QUINCLORAC 

75DF SP ALBAUGH INC 75

42750-131 

QUINCLORAC 75 

SWF ALBAUGH INC 75

71085-26 RICEPRO RICECO LLC 2

73220-15 

QUALI-PRO 

QUINCLORAC 75 

FARMSAVER.COM, 

LLC 75

79676-22 

QUINCLORAC GPRO 75 DF GRO-PRO, LLC 75

81927-21 

ALLIGARE 

QUINCLORAC 75 

WDG ALLIGARE, LLC 75

AR070006 RICEPRO RICECO LLC 2

UT990003 

FACET 75 DF 

HERBICIDE 

BASF 

CORPORATION 75

98ND20 

ND Dept. of 

Agriculture 

98NE07 

NE Department of 

Agriculture 
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 III. 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 

LC50 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. 

LD50 Median Lethal Dose. A statistically derived single dose that can be 

expected to cause death in 50% of the test animals when administered by 

the route indicated (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 Identification (number). EPA's system of recording and 

tracking submitted studies. 
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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 

ppb Parts Per Billion 

PPE Personal Protective Equipment 

ppm Parts Per Million 

PRZM/EXAMS Tier II Surface Water Computer Model 

Q1* 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 (Registrations Under Section 24©) of FIFRA) 

TGAI Technical Grade Active Ingredient 

USDA United States Department of Agriculture 

UF Uncertainty Factor 

WPS Worker Protection Standard
IV. Ecological Risk Assessment Problem Formulation

U. S. ENVIRONMENTAL PROTECTION AGENCY

Washington, D.C. 20460 

 OFFICE OF 

PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES 

 

Date: November 27, 2007 

MEMORANDUM 

Subject: EFED Problem Formulation for Quinclorac Registration Review 

 PC: Code: 128974 D344485

To: Joy Schnackenbeck, Chemical Review Manager 

Special Review and Reregistration Division (7508P) 

From: Marie Janson, Environmental Scientist, ERBI 

 Thuy Nguyen, RAPL, ERBI 

Nancy Andrews Ph.D., Branch Chief, ERBI 

Environmental Fate and Effects Division (7507P) 

Attached is the EFED’s problem formulation document in support of the Quinclorac registration 

review docket opening. This memorandum outlines (1) the methods that will likely be used in 

the ecological risk assessment of Quinclorac (2) data gaps, and (3) additional data needs. 
17

EXECUTIVE SUMMARY 

Quinclorac is systemic pre- and post-emergent herbicide to control broadleaf and grass weeds on 

residential/commercial turf grasses and on other turf grasses (picnic grounds, athletic field, golf, 

and sod farms), agricultural fallow/ idleland, agricultural rights of way/ fence rows/ hedge rows, 

grasses grown for seed, rice, sorghum and wheat. In addition to the above registered uses, 

Emergency Use Permits (EUPs) on impounded waters were also issued. 

The most recent comprehensive risk assessment for registered uses was conducted on wheat and 

sorghum (Feb 17, 1999). The most recent EUP was conducted on aquatic weed control to nonflowing water bodies (May 17,2007). The drinking water assessment was conducted on turf grass 

application (September 13, 2007). 

Based on the results of the above risk assessments the following risk concerns were noted from 

registered uses: 

- risks to listed and non-listed terrestrial plants wheat and sorghum applications 

- (listed and non-listed) acute risk to birds from wheat and sorghum applications* 

Based on the results of the above EUP for aquatic weed control the following risk concerns were 

noted: 

- risks to listed and non-listed terrestrial plants (spray drift exceedences only) 

- risks to non listed* and listed unicellular and vascular plants 

- (listed and non-listed) acute and chronic risk to mammals* 

- (listed and non-listed) acute and chronic risk to birds* 

There is insufficient evidence to completely refute these exceedences, however there is sufficient 

evidence to refine the concerns. 

Based on available laboratory studies, EFED has identified two major (BH 514-1 and BH 514 2-

OH; >10% applied)) and one minor (BH 514-HMe-ester; <10% applied) quinclorac metabolites. 

In most of the acceptable terrestrial field dissipation studies (1988/1989, 1989/1990, and 

1996/1997 studies), leaching from these degradates. An acceptable guideline 

adsorption/desorption study for BH-514-1 indicates that this metabolite is mobile to very mobile 

in sand, sandy loam, loam, clay loam, and silty clay soils. Two guideline leaching and 

adsorption/desorption studies (MRID 45598701 and 45598702) for BH 514 2-OH and BH 

514-HMe-ester were submitted to the Agency, in 2002, however not yet reviewed. 

These studies will undergo reviews and until they are deemed acceptable by the Agency, the 

above mentioned metabolites are considered potential contaminants of groundwater resources, 

based on the “Acceptable” field studies. EFED believes that since quinclorac is persistent and 

mobile and its metabolites have the ability to leach through soil profiles, the potential for 

groundwater impacts to non-target crops via contaminated groundwater is likely. Therefore, a

small scale prospective groundwater contamination study for quinclorac (and possibly its 

metabolites) under the expected conditions of use of all currently registered crops is requested. 
18

EFED anticipates revisions to the risk assessments based on new application scenarios and 

additional toxicity data requested. Previous assessments were based on lower application 

scenarios or higher intervals between applications. 

 

PROBLEM FORMULATION 

 

Problem formulation is used to establish the direction and 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, formulation 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 Quinclorac on residential/commercial turf grasses and 

on other turf grasses (picnic grounds, athletic field, golf, and sod farms), agricultural fallow/ 

idleland, agricultural rights of way/ fence rows/ hedge rows, grasses grown for seed, rice, 

sorghum and wheat could result in exposures that cause unreasonable adverse effects (risk) to 

non-target organisms including those federally listed as threatened or endangered (hereafter 

referred to as “listed”). Emergency Use Permits also will also be characterized in the 

assessment on aquatic weed control on impounded waters. 

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: 

• Feb 17, 1999, Quinclorac Herbicide Environmental Fate and Ecological Effects 

 Assessment and Characterization for a Section 3 for Use on Wheat and Sorghum 

• May 17, 2007, Ecological Risk Assessment for Experimental Use Permit for Quinclorac 

 for Aquatic Weed Control for the application of quinclorac to non- flowing water bodies 

 such as retention ponds and lakes to evaluate the control and selectivity of submerged 

 and emergent aquatic weed species DPBarcode: D334717. 

• September 13, 2007, Estimated Drinking Water Assessment for Quinclorac (3,7-dichloro-8-

quinolinecarboxylic acid, CAS# 84087-01-4) Use on Turfgrasses DPBarcode: 341487 

Based on the results of the above risk assessments the following risk concerns were noted from 

registered uses: 
19

- risks to listed and non-listed terrestrial plants from wheat and sorghum applications 

- (listed and non-listed) acute risk to birds from wheat and sorghum applications* 

Based on the results of the above EUP for aquatic weed control the following risk concerns were 

noted: 

- risks to listed and non-listed terrestrial plants (spray drift exceedences only) 

- risks to non listed* and listed unicellular and vascular plants 

- (listed and non-listed) acute and chronic risk to mammals* 

- (listed and non-listed) acute and chronic risk to birds* 

There is insufficient evidence to completely refute these exceedences, however there is sufficient 

evidence to refine the concerns. 

The following maximum use rates were used in previous assessments: 

Feb 17, 1999, Section 3 Assessment for Use in Wheat and Sorghum: The maximum annual 

application rate is 0.75 lb a.i./acre at 0.125 - 0.245 lb ai/acre for ground and aerial applications. 

 

September 13, 2007, Estimated Drinking Water Assessment for Quinclorac Use on Turfgrasses: 

The maximum annual application rate is 1.5 lb a.i./acre at 0.25 – 0.75 lb ai/A/ appl at 21-day 

interval for ground spray or spot spray application. 

May 17, 2007, Ecological Risk Assessment for Experimental Use Permit for Quinclorac 

for Aquatic Weed Control: For submerged vegetation control quinclorac is applied in sufficient 

quanity to reach a water concentration of 0.5 mg/L with up to 2 applications per year. 

All assessments did not provide the highest labeled application rates (2 applications @0.75 lb 

ai/A) and current minimum intervals (14 days). In addition, current labels have ground, aerial 

and granular applications which were not incorporated in all assessments. Therefore, a new 

drinking water assessment and ecological risk assessment is required with the above maximum 

application rates, minimum intervals and application scenarios. 

There are two reported incidents for quinclorac. Both incidents ref# I012162-001 and ref# 

I015496-001 indicated plant damage to tomatoes in Arkansas from drift exposure. There are 

additional data that suggest the effects of primary drift may occur at considerable distances 

downwind from the target site and effect commercial yields of sensitive crops. Additional 

information is summarized in the 1999 EFED risk assessment in the Risk Characterization 

Section on Non-Target Plant Effects (Drift Implications for Risks to Non-Target Crops and Wild 

Plants). 
20

2. DATA GAPS AND ANTICIPATED DATA NEED 

 

Acute and chronic freshwater invertebrate toxicity tests- The acute freshwater invertebrate 

toxicity test was based on a formulated product (quinclorac with surfactant BAS 864 01 S). 

The Daphnia magna 21-day NOAEC of 110 mg/L is used as the freshwater invertebrate toxicity 

endpoint for chronic exposure. It should be noted that the 21-day NOAEC unexpectedly exceeds 

the 48-hour EC50 for the same species. This observation is likely the result of differences in test 

water conditions, or as the result of surfactant use in the acute toxicity test. As quinclorac is an 

acid subject to dissociation in water, differences in water hardness may influence the toxicity of 

the compound. The available data suggest that quinclorac is more toxic to freshwater 

invertebrates in soft water (48-hour LC50= 28.9 mg/l in water 40-48 mg CaCO3/L) compared to 

harder water (21-day NOAEC 110 mg/l in water >150 mg CaCO3/L). An alternative explanation 

for the disparate toxicity results may be the presence of surfactant in the acute test, whereas no 

surfactant is evident for the chronic test. The use of the available 21-day chronic data as the 

toxicity endpoint for all freshwater systems represents an uncertainty. 

Decision: Acute and chronic freshwater invertebrate studies conducted on TGAI and current 

guideline requirements are requested. This data will then be used to estimate values for estuarine 

marine invertebrate chronic toxicity. 

 

Estuarine marine fish and estuarine marine invertebrate Early Life-Stage toxicity tests- No 

early life-stage or full life-cycle studies were submitted for estuarine marine fish or invertebrates. 

Decision: Early life-stage chronic estuarine marine fish and invertebrate toxicity tests for 

quinclorac are not requested. Estimated values derived from ACRs will be sufficient pending 

acute and chronic freshwater invertebrate study based on TGAI. 

Ground water contamination study for quinclorac (and possibly its metabolites): 

Based on available laboratory studies, EFED has identified two major (BH 514-1 and BH 514 2-

OH; >10% applied)) and one minor (BH514-HMe-ester; <10 % applied) quinclorac metabolites. 

In the field (1988/1989, 1989/1990, and 1996/1997 studies), leaching from these degradates into 

the soil profiles were observed. An acceptable guideline adsorption/desorption study for BH514-1 indicated that this metabolite is mobile to very mobile in sand, sandy loam, loam, clay 

loam, and silty clay soils. Two guideline leaching and adsorption/desorption studies (MRID 

45598701 and 45598702) for BH 514 2-OH and BH 514-HMe-ester were submitted to 

the Agency, in 2002, however not yet reviewed. These studies will undergo reviews 

and until they are deemed acceptable by the Agency, the above mentioned metabolites are 

considered potential contaminants of groundwater resources, as suggested by data from the 

“Acceptable” terrestrial field dissipation studies. 
21

Decision: Based on the environmental persistence of quinclorac, its potential to enter 

groundwater (as modeled by SCI-GROW and indicated in terrestrial field studies), and the 

potential for groundwater impacts to non-target crops via contaminated groundwater, a small 

scale prospective groundwater contamination study for quinclorac (and possibly its metabolites) 

under the expected conditions of use of all currently registered crops is requested. Specifically, 

since both parent quinclorac and BH 514-1 are carboxylic acids, they are expected to be anions 

under the normal environmental pH range (5.5 – 8.5), therefore possess high potential to be 

mobile in mineral soils. 

 

3. PESTICIDE TYPE, CLASS, AND MODE OF ACTION 

Quinclorac is a quinoline carboxylic acid. The mechanism of herbicidal action is generally 

similar to the mechanism for the phenoxy herbicides (i.e., mimicry of the plant growth hormone 

auxin). The risk assessment only assesses parent quinclorac risks. For most fate processes the 

parent compound is stable. While quinclorac may be relatively rapidly photo-labile in natural 

waters, the available studies of this fate process have not chemically identified degradates or 

their rate of production. There is therefore insufficient information to assess degradate risks with 

any useful degree of confidence and no information is available to suggest that any degradates 

could be biologically active. 

4. STRESSOR SOURCE AND DISTRIBUTION 

The stressor of this assessment is identified by the chemical name 3,7-dichloro-8-

quinolinecarboxylic acid. The trade name for this compound is quinclorac, the CAS number is 

84087-01-4, and the PC code is 128974. Currently, quinclorac is applied as ground spray, aerial 

spray, aerial granular, ground granular applications. 

Laboratory data indicate that quinclorac is stable to hydrolysis, photolysis in sterile water, as 

well as aerobic and anaerobic metabolism in soil. Conversely, quinclorac undergoes rapid 

photolysis in non-sterile rice paddy, natural river waters, and solutions containing activated 

sewage sludge (half-lives of 5-10 days). Photolysis on soil surface is also a route of dissipation 

with a mean half life of 141 days. Field studies reviewed to date indicate that quinclorac is 

moderately persistent (18-176 days half-lives) in terrestrial environment. 

The adsorption coefficients Kd of less than 1 suggest that leaching could be a route of 

dissipation. In the field, some leaching was observed, as quinclorac was detected below the 12 

inch soil depth in the several of the terrestrial field dissipation studies (1988/1989 studies): 

detections of residues of quinclorac and its degradates in the soil down to 42-48 inches 

(quinclorac), 12-18 inches (BH 514-2-OH) and 6-12 inches (BH 514-ME) were noted in 

terrestrial field studies performed in KS, CA, MO, and NJ. 

Runoff under normal field situations to near surface water is also expected, since Kd is low 

(<1.0) and the chemical can be applied near the soil surface (pre emergence). 
22

5. OVERVIEW OF PESTICIDE USAGE 

Quinclorac is a pre- and post-emergent herbicide to control broadleaf and grass weeds on 

residential/commercial turf grasses and on other turf grasses (picnic grounds, athletic field, golf, 

and sod farms), agricultural fallow/ idleland, agricultural rights of way/ fence rows/ hedge rows, 

grasses grown for seed, rice, sorghum and wheat. In addition, quinclorac controls submerged 

and emergent aquatic weed species in impounded waters for EUPs. 

The highest annual application rate among all registered and proposed uses is via Drive 75 DF 

and Quinclorac G-Pro 75 DF labels, which allows 2 to 3 ground broadcast or spray spot 

applications of 0.25, 0.50, or 0.75 lb ai/A per application, not exceeding 1.5 lb ai/A/year. 

Sequential applications should be timed 14 days apart. Additional maximum rate application 

scenarios are provided in Table 1 for aerial, ground and granular applications based on BEAD 

2007 information. Table 30 provides all current registrations and EUPs based on BEAD 2007 

information. 

Table 1 Maximum Quinclorac Aerial, Ground and Granular application rate 

scenarios derived from BEAD 2007 to be used in future risk assessments* 

Type of 

application Label 

Maximum 

applicatio

n rate 

Maxim

um # 

apps Maximum application per season 

aerial spray 

and aerial 

granular 

applications 

7969-158 Facet 

GR(aerial), 42750-88 

Quinclorac 75 DF 

AG,7969-93 Facet 50 

WP 

0.5 lb ai/A 1 0.5 lb ai/A 

aerial spray 

application 

42750-131 Quinclorac 

SWF 

0.375 lb 

ai/A 

2 0.75lb ai/A 

ground 

granular 

application 

583-296 Scotts turf 

builder 

0.75 Lb 

ai/A 

2 Not specified (assume 2@ 0.75) 

60 day interval 

ground spray 

application 

7969-130 Drive 75 

DF and 79676-00022 

Quinclorac G-Pro 75 

DF 

0.75lb 

ai/A 

2 1.5 lb ai/A 

*assume 14 day interval unless indicated 

 The application rate for emergent vegetation control is indicated on the proposed label for the 

EUP to be a maximum of 3 lbs a.i. per year, with up to two applications in a calendar year. 

Applications can be made to drawn down water bodies to expose vegetation. In such cases reflooding may occur 14 days after application. The application rate for submerged vegetation is 

quinclorac applied in sufficient quantity to reach a water concentration of 0.5 mg/L. Up to two 

application of quinclorac per year can be made. 
23

6. ENVIRONMENTAL FATE SUMMARY

ENVIRONMENTAL FATE

For persistence, laboratory data indicate that quinclorac is stable to hydrolysis, photolysis in 

sterile water, as well as aerobic and anaerobic metabolism in soil. Conversely, quinclorac 

undergoes rapid photolysis in non-sterile rice paddy, natural river waters, and solutions 

containing activated sewage sludge (half-lives of 5-10 days). Photolysis on soil surface is also a 

route of dissipation with a mean half life of 141 days. Field studies reviewed to date indicate 

that quinclorac is moderately persistent (18-176 days half-lives) in terrestrial environment. 

For mobility in terrestrial environment, the adsorption coefficients Kd of less than 1 suggest 

that leaching could be a route of dissipation. In the field, some leaching was observed, as 

quinclorac was detected below the 12 inch soil depth in the several of the terrestrial field 

dissipation studies (1988/1989 studies): detections of residues of quinclorac and its degradates in 

the soil down to 42-48 inches (quinclorac), 12-18 inches (BH 514-2-OH) and 6-12 inches (BH 

514-Me ester) were noted in terrestrial field studies performed in KS, CA, MO, and NJ. It is not 

clear from these studies whether or not the metabolite BH 514-1 was analyzed for at the time the 

studies were conducted. However, as referenced in the April 25, 1996 letter to Mr Robert Taylor, 

RD, EPA, the registrant claimed a reanalysis (no analysis date was specified) of the soil samples 

from the 1988/1999 studies did not detect presence of this carboxylic acid metabolite. 

Additional studies performed between 1989 and 1990 in FL, WI, and NY only showed 

movement of parent quinclorac to a maximum depth of 24 inches, while the degradate BH-514-1 

was not found at any sampling interval and/or sampling depths. These studies and the details of 

the reanalyses of BH 514-1 have not yet been received nor reviewed by EFED. Two guideline 

leaching and adsorption/desorption studies (MRID 45598701 and 45598702) for BH 514 2-

OH and BH 514-HMe-ester were submitted to the Agency, in 2002, however not 

yet reviewed. EFED SCI-GROW model predicts an upper bound ground water exposure 

concentration of 29 μg/L for parent quinclorac. 

In summary, based on all “Acceptable” guideline studies, EFED concludes that quinclorac has 

has the potential to leach and runoff in the soil environment and into groundwater. Furthermore, 

BH 514-1, the primary degradate of quinclorac, also has the potential to leach to the groundwater 

in soil containing low amount of clay or organic matter. EFED notes that quinclorac and BH514-1 are both carboxylic acids; therefore, they are expected to be anions under the normal 

environmental pH range (5.5-8.5). This suggests that these two chemicals have great potential to 

be mobile in mineral soils. 

Runoff under normal field situations to near surface water is also expected, since Kd is low 

(<1.0) and the chemical can be applied near the soil surface (pre emergence). For 1 in 10 year 

annual peak (acute) surface water residue, EFED PRZM/EXAMS estimates a value of 22.9 μg/L; 

for 1 in 10 year annual mean (chronic), 14.5 μg/L; and for 30 year annual mean (cancer), 10.3 
24

μg/L. Note that all values were based on post emergence non residential turf uses ,such as picnic 

grounds, athletic fields, sod farms, etc, ... The acute value was estimated from the FL Turf 

scenario, and the chronic and cancer from the PA Turf scenario. 

According to the aerobic soil metabolism and field dissipation studies and the research cited in 

the literature reviews, the fate of quinclorac can be described as such: 

1. Quinclorac is initially metabolized to the primary degradate, 3-chloro-8-quinoline 

carboxylic acid (BH 514-1). This degradate undergoes further degradation to 5-chloro2-hydroxy-nicotinic acid, which in turn is metabolized to 5-chloro-2,6-dihydroxynicotinic acid, 2 hydroxy-3-chloro-8-quinoline carboxylic acid (BH 514 2-OH), 7-

chloro-8-quinoline carboxylic acid, 8-quinoline carboxylic acid, and other small 

fragments. These compounds can then bind with or become incorporated into the soil or 

humic material of the soil as a part of natural soil components (i.e., carbon pool of the 

soil), and/or can degrade to CO2, a major terminal product. 

2. The only volatile compound detected in the aerobic soil metabolism study (MRID 

44084503) was CO2 at a maximum concentration of 7.1% TRR. Other than parent, 

residues identified at maximum concentrations were: BH 514 2-OH (14.9% TRR), BH 

514-Me ester (7.8% TRR). Parent was found at maximum concentrations of 58.1% 

TRR. 

3. BH 541-1 was also reported in the aerobic aquatic metabolism (MRID 42294102), at 

maximum of 55.7% of the initial radioactivity after 6 months and 30.8% after 12 

months. Adsorption/desorption studies determine that this degradate is less mobile than 

its parent, with Kd’s ranging from 1.56 in sand soil, 1.97 in sandy loam soil, 11.4 in loam 

soil, 13.3 in clay loam soil, and 30.2 in silty clay soil. This degradate was not reported 

in any of the terrestrial field dissipation studies, at any soil depth. 

For mobility in aquatic environment, aquatic field dissipations studies with rice indicate that 

the compound is less stable than predicted by the laboratory and is probably not mobile under 

normal use conditions. 

For volatility, both vapor pressure (7.5 x 10-8 mm Hg at 20o

 C) and Henry's Law Constant (1.22 

to 24.3 x 10-15 atm.m3

 mol-1 ) indicate a low possibility of volatilization from soil and water. 

Bioaccumulation in fish is not expected according to the acceptable fish accumulation study, 

which showed that after 28 days of exposure, quinclorac did not accumulate in channel catfish. 

No BCF value was reported (MRID 40320819 and 41063559). Furthermore, the octanol/water 

partition coefficient (KOW) of 0.266 also suggests that quinclorac has low potential to 

bioaccumulate. 

A detailed assessment of the environmental fate of Quinclorac could be found in the 

“Environmental Fate and Ecological Effects Assessment and Characterization for a Section 3 for 

Use on Wheat and Sorghum” report dated March 05, 1999 (DP Barcodes: 250179, 248882, 

248884, 192866, 231399, and 238400). The chemical structures of quinclorac and its 2 major 

metabolites (BH 514-1 and BH 514 2-OH) are shown in Table 29. 

 
25

7. ECOLOGICAL EFFECTS SUMMARY 

Table 2 provides taxonomic groups and test species used to indicate the potential for ecological 

effects in this screening-level risk assessment. Within each of these very broad taxonomic 

groups, an acute and/or chronic endpoint is selected from the available test data. 

Table 2. Taxonomic Groups and Most Sensitive Test Species Evaluated for Ecological 

Effects of Quinclorac *

Taxonomic group Example(s) of representative species Endpoint Used

Birdsa Bobwhite quail (Colinus virginianus) 

Mallard duck (Anas platyrhynchos) 

Bobwhite quail (Colinus virginianus) 

Acute LC50 5000 mg/kg-diet 

Acute LD50 >1900 mg/kg-bw 

Chronic, NOAEC 500 mg/kgdiet 

Mammals Laboratory rat (Wistar) Acute LD50 2190 mg/kg-bw 

NOAEC 160 mg/kg-bw/day 

Terrestrial insects Honeybees (Apis mellifera) Acute Contact LD50>181 

ug/bee

Freshwater fishb Bluegill sunfish (Lepomis macrochirus) 

Fathead minnow (Pimephales promelas)

Acute LC50 31.6 mg/L 

Chronic NOAEC 16 mg/L 

Freshwater invertebrates Water flea (Daphnia magna) 

 

Acute EC50 29.8 mg/L 

NOAEC 110 mg/L 

Estuarine/marine fish Sheepshead minnow (Cyprinodon 

variegatus) 

Acute LC50 >94.4 mg/L 

NOAEC no studies submitted 

or values determined. 

However, estimated values 

derived from acute to chronic 

ratios will be used in future 

risk assessments. 
26

Table 2. Taxonomic Groups and Most Sensitive Test Species Evaluated for Ecological 

Effects of Quinclorac *

Taxonomic group Example(s) of representative species Endpoint Used

Estuarine/marine invertebrates Mysid shrimp (Mysidopsis bahia) 

 

Acute EC50 69.4 mg/L 

NOAEC no studies submitted 

or values determined. 

However, estimated values 

derived from acute to chronic 

ratios will be used in future 

risk assessments. 

Terrestrial plants* Dicots – carrot 

Dicots- tomato 

Seedling Emergence EC25

0.004 lb a.i./acre, NOAEC 

<0.004 lb a.i./acre 

Vegetative Vigor EC25 

EC25 0.007 lb a.i./acre, 

NOAEC 0.5 lb a.i./acre 

Vascular aquatic plants Duckweed (Lemna gibba) Tier1 Acute EC50 >0.5 mg/L 

NOAEC 0.5 mg/L 

 Non-vascular aquatic plants Green algae (Selanastrum capricornutum ) 

Freshwater diatom (Navicula pelliculosa) 

Marine diatom (Skeletonema costatum) 

Bluegreen alga (Anabaena flos-aquae)

Acute EC50 >0.5 mg/L 

NOAEC 0.5 mg/L 

 

a

Birds are used as surrogates for terrestrial phase amphibians and reptiles (US EPA, 2004). b

Freshwater fish are used as surrogates for aquatic phase amphibians (US EPA, 2004). 

* Dicots were the most sensitive terrestrial plant species tested, however the most sensitive monocots for seedling emergence is 

onion (EC25 0.118 lb, NOAEC<0.118 lb ai/A) and for vegetative vigor is corn ( EC25 1.09 lb a.i./acre, NOAEC 0.5 lb ai/A) 

8. ECOSYSTEMS AT RISK 

The ecosystems that could be potentially at risk due to agricultural and ornamental turf use of 

quinclorac include terrestrial and aquatic (lakes, ponds, streams and estuarine marine water 

bodies) habitats in proximity to quinclorac use areas. These habitats may be at risk from drift 

and/or runoff of quinclorac from use areas. 

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 for given species/taxa based on the screening-level 

assessment, then risks might be expected to translate to higher levels of biological organization. 
27

Identifying specific ecosystems at risk in a screening-level assessment is beyond the scope of the 

effort. 

8.1 Receptors 

 The aquatic receptors likely to be exposed to quinclorac from turf and rice applications 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 quinclorac 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. The above taxonomic groups exposed to quinclorac are 

simular for impounded waters as well. 

8.2. Assessment Endpoints 

Assessment endpoints are defined as “explicit expressions of the actual environmental value that 

is to be protected.” Operationally, the environmental value is represented by an ecological entity 

and associated attributes or characteristics. The assessment endpoints for this ecological risk 

assessment will be survival, growth, and reproduction of terrestrial and aquatic animals and 

plants. Specifically, this assessment will address birds, mammals, reptiles, amphibians, 

terrestrial and aquatic invertebrates, terrestrial and aquatic plants, and fish. These endpoints, in 

turn, are meant to reflect population sustainability and community diversity within ecosystems. 

Assessment endpoints and toxicity data used to evaluate the assessment endpoints are identified 

in Table 2. 
28

9. CONCEPTUAL MODEL 

Figure 1. No conceptual model was provided in previous assessments, however this new 

conceptual model of the fate/transport and effects of Quinclorac applied to the terrestrial 

environment will be applied in future assesssments. In addition, granular applications will be 

assessed in future risk assessments. 

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 

 Quinclorac applied by spray (ground and aerial) and granular (ground and aerial) applications 

 

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 

Groundwater 

Direct 

Ingestion 
29

*The vapor pressure of quinclorac, reported to be 1 x 10-7 mbar (0.76 x 10-7 mm Hg) at 20o C, and Henry's 

Law Constant both indicate a low possibility of volatilization. 

For direct application to the aquatic environment, the conceptual model of the fate/transport and 

effects of Quinclorac will be used from the May 17, 2007 Ecological Risk Assessment for 

Experimental Use Permit for Quinclorac for Aquatic Weed Control DP Barcode: D334717.

10. RISK HYPOTHESES

Used in accordance with proposed or existing labels quinclorac may: 

 

• adversely affect growth, survival, or fecundity of birds and/or small mammals (and 

terrestrial amphibians and reptiles) ingesting the incidentally contaminated vegetation, 

seeds, fruits, or invertebrates associated with direct application to terrestrial plants, soil 

surface, drained impounded water bodies or the intentionally treated bait or seed stock, 

• adversely affect growth, survival, and or reproduction of aquatic invertebrates, fish, 

amphibians in both freshwater and estuarine marine environments, 

• adversely affect the emergence or growth of terrestrial plants receiving exposure either by 

drift from treated areas under conditions of ground or aerial spray. 

 

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 risk 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 quinclorac 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 models commonly used in 

pesticide risk assessments (EPA, 2004). Generally, aquatic exposure estimates are generated 

from EFED models and incorporate maximum proposed use rates and empirically-derived fate 
30

properties. Aquatic exposure will be estimated using the Tier 1 GENEEC 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 empirically determined observations of pesticide 

residues on various terrestrial food items. For numerous applications for a given use, the 

exposure model incorporates a first-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 estimated using the TerrPlant model that assumes 

quinclorac drifts or moves with runoff to adjacent areas. 

 Listed Species Assessment 

Based on preliminary EECs from terrestrial application scenarios and the assumptions discussed 

above, acute risks at the highest labeled application rate are expected for listed birds based on the 

non-definitive LD50 of >1900 mg/kg-bw (1.5 lbs a.i./A per season) Risks are expected as well 

for listed species of terrestrial plants (monocots and dicots) inhabiting semi-aquatic and dry areas 

based on exposures of quinclorac originating from the maximum application rate. 

 

Based on preliminary EECs from direct application to a water body and the assumptions 

discussed above, acute risks at the highest labeled application rate are expected for listed birds, 

mammals, terrestrial plants (monocots and dicots) and aquatic non-vascular plants. 

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). An evaluation of 

risk conclusions based on direct and indirect effects for each taxonomic group will be 

summarized in the future assessment for all proposed labels. 

If the planned ecological risk assessment continues to indicate that quinclorac may potentially 

impact, either directly or indirectly, 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 quinclorac “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, whether the expected impacts are “likely to adversely 

affect” the critical habitat. The first step in the process is to improve the exposure estimates 
31

based on refining the geographic proximity of quinclorac use and the listed species and/or critical 

habitat. If there is no geographic proximity, this information would support a determination that 

quinclorac use will have no effect on the species or critical habitat. If after conducting the first 

step of this analysis the Agency determines that geographic proximity exists, both potential 

direct effects and any potential indirect effects 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’), consistent 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. Analytically, 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 habitat or the occupied range of any listed species. If so, EPA would 

examine whether quinclorac potential impacts on non-endangered species would affect the listed 

species indirectly or directly affect a constituent element of the critical habitat. Alternatively, the 

agencies could determine which listed species depend on biological resources, or have 

constituent elements that fall into, the taxa that may be directly or indirectly impacted by 

quinclorac. Then EPA would determine whether the use of quinclorac overlaps the critical 

habitat or the occupied range of those listed species. 

11.2. Measures of Effect 

 EFFECTS ASSESSMENT 

The Effects assessment for this risk assessment has been based on previous risk assessment data 

evaluations conducted in 1999. There has been no update of the toxicological review of the 

compound in the intervening years. These risk assessments DO NOT include a search and 

evaluation of the ECOTOX database. 

 Toxicity to Terrestrial Animals

Acute and Subacute Avian Toxicity

The results of available avian acute toxicity tests are listed in Table 3. The most sensitive 

species is the mallard duck (LD50 >1900 mg/kg, LD50 value expressed on a bodyweight-based 

dose), which serve as the toxicological endpoint in avian single oral dose exposure risk 

calculations. 

Table 3 Avian Acute Oral Toxicity Data

Species % Active 

Ingredient 

LD50 

(confidence limits) 

MRID No. Classification 
32

(mg/kg-bw) 

Northern bobwhite quail 

Colinus virginianus

98 >2000 

(no mortality at 2000) 

41063547 acceptable 

Mallard duck 

Anas platyrhynchos

98 >1900 

(no mortality at 970, 

20% mortality and 

convulsions at 1900) 

40320810 supplemental* 

LD50: Lethal dose to 50% of test population 

NOAEL: No observed adverse effect level

* listed as supplemental due to questionable husbandry practices (e.g., the necks of ducks bound with bands to 

prevent regurgitation)

 The results of available avian sub-acute dietary testing are summarized in Table 4. The LC50 of 

>5000 mg/kg-diet exhibited for both northern bobwhite quail and the mallard duck serve as the 

basis of the toxicological endpoint for sub-acute dietary exposure risk calculations. 

Table 4 Avian Subacute Dietary Toxicity Data

Species % Active 

Ingredient 

LC50 

(confidence limits) 

(mg/kg-diet) 

MRID No. Classification 

Northern bobwhite 

quail Colinus 

virginianus

96 >5000 

(no mortality to 2500)

40320812 acceptable 

Mallard duck Anas 

platyrhynchos

96 >5000 

(no mortality to 5000)

40320811 acceptable 

LC50: Lethal dietary concentration to 50% of test population 

NOAEC: No observed adverse effect concentration 

Chronic Avian Exposure Effects

The results of avian reproduction testing are listed in Table 5. The northern bobwhite 

reproduction NOAEL of 500 mg/kg-diet serves as the reproduction toxicity endpoint for avian 

reproduction risk calculations. This NOAEL is established with respect to the most sensitive 

toxicity endpoint observed for the study, reduced survival of 14-day old hatchlings from eggs set. 

Table 5 Avian Reproduction Toxicity Data

Species % Active 

Ingredient 

LOAEC 

 (mg/kg-diet) 

NOAEC 

(mg/kg-diet) 

MRID No. Classification 

Northern bobwhite 

quail Colinus 

99.19 1000 (reduced 

14 day 

500 44129201 acceptable 
33

virginianus survivors of egg 

set) 

Mallard duck Anas 

platyrhynchos

99.19 >1000 1000 44084501 acceptable 

LOAEC: Lowest observed adverse effect concentration 

NOAEC: No observed adverse effect concentration 

Acute and Chronic Mammalian Toxicity

Acute mammalian toxicity data are summarized in Table 6. The most sensitive acute endpoint is 

for the laboratory rat (Wistar strain), with a minimum LD50 of 2190 mg/kg bodyweight. 

Table 6 Mammal Acute Toxicity Data

Species % Active 

Ingredient 

LD50

 (mg/kg) 

MRID No. Classification 

Rat (Wistar) technical male: 3060 

female: 2190 

41063506 acceptable 

Mouse (B6C3F1) technical >2000 41063507 acceptable 

LD50: Lethal dose to 50% of test population 

NOAEL: No observed adverse effect level

The following table summarizes the reproduction, and developmental toxicity data for laboratory 

mammals chronically exposed to quinclorac. For the purposes of this risk assessment, the rat 2-

generation reproduction study NOAEL of 160 mg/kg-bw/day for reduced pup viability was 

selected as the threshold for mammals chronically exposed to quinclorac. This value is quite 

similar to the threshold for rabbit developmental data, in which the NOAEL for increased fetal 

resorptions was 200 mg/kg-bw/day. 

Table 7 Mammal Chronic, Reproduction, and Developmental Toxicity Data

Species % 

Active 

Duration/ 

Study Type 

LOAEL 

 (mg/kg-diet) or 

(mg/kg-bw/day) 

NOAEL 

(mg/kg-diet) or 

(mg/kg-bw/day) 

MRID 

No. 

Classification 

Rat (Wistar) 96.5 3 month 

feeding 

12000 mg/kg-diet 

slight nephritis 

4000 mg/kg-diet 41063516 supplemental 

Rat (Wistar) 96.5 Developmental >438 

mg/kg-bw/day 

41063524 minimum 

Rabbit 98.3 Developmental 600 

mg/kg-bw/day 

increased fetal 

resorptions 

200 

mg/kg-bw/day 

41063525 minimum

 
34

Rat (Wistar) 97.40- 

98.3 

2 generation 

reproduction 

480 

mg/kg-bw/day 

reduced pup 

viability 

160 mg/kgbw/day 41063526 

41910001 

minimum

LOAEL: Lowest observed adverse effect level 

NOAEL: No observed adverse effect level

Beneficial Insect Toxicity

The available studies of quinclorac effects on honeybees (Table 8) indicate that technical 

quinclorac and the 50% formulation are relatively non-toxic to bees on an acute contact basis 

Table 8 Beneficial Insect Toxicity Data

Species % Active 

Ingredient 

LD50

 (μg/bee) 

NOAEL 

(μg/bee) 

MRID No. Classification

Honeybee 

Apis mellifera

98 >357 238 41063575 acceptable 

Honeybee 

Apis mellifera

50 >181 <60.4 

(lowest dose 

tested) 

41063576 acceptable 

LD50: Lethal dose to 50% of test population 

NOAEL: No observed adverse effect level

Terrestrial Plant Toxicity

 

Table 9 summarizes the available data for the effects of quinclorac on terrestrial plants. The 

toxicological threshold for seedling emergence used in the risk assessment is based on the carrot 

EC25 of 0.004 lb a.i./acre. The toxicological threshold for vegetative vigor used in the risk 

assessment is based on the tomato EC25 of 0.007 lb a.i./acre. 

 

Table 9 Terrestrial Plant Toxicity Data

Species % Active 

Ingredient 

Test 

Type 

EC25 

(lb a.i./acre) 

NOAEC 

(lb a.i./acre) 

MRID No. Classification for 

all 

Soybean 96 SE 0.047 <0.047 41403501 

Glycine max

96 VV 0.203 0.125 41403503 

Lettuce 96 SE 0.013 <0.01 41403501 

Lactuca sativa

96 VV 0.01 <0.01 41403503 

Carrot 96 SE 0.004 <0.004 41403501 

Daucus carota

96 VV 0.027 0.02 41403503 

 

acceptable
35

Species % Active 

Ingredient 

Test 

Type 

EC25 

(lb a.i./acre) 

NOAEC 

(lb a.i./acre) 

MRID No. Classification for 

all 

Tomato 96 SE 0.026 0.02 41403501 

Lycopersion 

esculentum 96 VV 0.007 0.005 41403503 

Cucumber 96 SE 0.012 <0.012 41403501 

Cucumis sativus

96 VV 0.028 0.012 41403503 

Cabbage 96 SE 0.162 0.125 41403501 

Brassica 

oleracea 96 VV 26.0 2.0 41403503 

Oat 96 SE 0.771 <0.77 41403501 

Avena sativa

96 VV 68.3 2.0 41403503 

Ryegrass 96 SE 0.271 <0.27 41403501 

Lolium perenne

96 VV >2.0 2.0 41403503 

Corn 96 SE 0.211 <0.211 41403501 

Zea mays

96 VV 1.09 0.5 41403503 

Onion 96 SE 0.118 <0.118 41403501 

Allium cepa

96 VV 12.33 2.0 41403503 

SE: seedling emergence 

VV: vegetative vigor 

EC25: Effective concentration for 25% reduction in emergence or growth measures 

NOAEL: no observed adverse effect level

Toxicity to Aquatic Animals

Freshwater Fish Acute Toxicity

The results for available acute toxicity testing with freshwater fish (Table 10) indicate that 

quinclorac is slightly toxic to fish on an acute basis. The guideline requirement (72-1) 

is fulfilled. The bluegill sunfish LC50 of 31.6 mg/L is used as the acute freshwater toxicity 

endpoint for the risk assessment. 

Table 10 Freshwater Fish Acute Toxicity Data

Species % Active 

Ingredient 

LC50 

(confidence limit) 

 (mg/L) 

MRID No. Classification 

Bluegill sunfish 

Lepomis macrochirus

96 31.6 (26.7-39.6) 41063555 acceptable 

 
36

Rainbow trout 

Oncorhynchus mykiss

96 >83.5 

(no mortality at 

highest dose tested) 

41063548 acceptable 

LC50: Lethal concentration to 50% of test population 

NOAEC: No observed adverse effect concentration

Freshwater Fish Toxicity from Chronic Exposure

The following table summarizes the available freshwater fish toxicity data from chronic 

exposure. 

Table 11 Freshwater Fish Chronic Toxicity Data (Early Life Stage Study)

Species % Active 

Ingredient 

LOAEC 

 (mg/L) 

NOAEC (mg/L) MRID No. Classification 

Fathead minnow

Pimephales 

promelas

technical 31 (larval 

growth) 

16 44084502 acceptable 

LOAEC: Lowest observed adverse effect concentration 

NOAEC: No observed adverse effect concentration 

Freshwater Invertebrate Acute Toxicity

Results of invertebrate toxicity testing are listed in Table 12. The results indicate that quinclorac 

is slightly toxic to aquatic invertebrates on an acute basis. The Daphnia magna EC50 of 29.8 

mg/L serves as the freshwater invertebrate toxicity endpoint for risk assessment. A freshwater 

aquatic invertebrate toxicity test using the technical grade of the active ingredient is required to 

assess the toxicity of a pesticide to freshwater invertebrates. Results of invertebrate toxicity 

testing are listed in the table below. The results indicate that quinclorac is slightly toxic to 

aquatic invertebrates on an acute basis. The guideline requirement (72-2) is fulfilled. 

Quinclorac was conducted on a formulated product (quinclorac plus surfactant) instead of TGAI. 

Therefore, use of the available acute data as the toxicity endpoint for all freshwater systems 

represents an uncertainty. 

Table 12 Freshwater Invertebrate Acute Toxicity Data

Species % Active 

Ingredient 

EC50 

(confidence limit) 

 (mg/L) 

MRID No. Classification 

Daphnia magna 96 29.8 (23.8-42.4) 41063556 acceptable 
37

EC50: Effective concentration to 50% of test population 

NOAEC: No observed adverse effect concentration

Freshwater Invertebrate Toxicity from Chronic Exposure

 

Data for freshwater invertebrate chronic toxicity are listed in Table 13. The guideline 

requirement (72-4) is fulfilled. 
38

The Daphnia magna 21-day NOAEC of 110 mg/L is used as the freshwater invertebrate toxicity 

endpoint for chronic exposure. It should be noted that the 21-day NOAEC unexpectedly exceeds 

the 48-hour EC50 for the same species. This observation is likely the result of differences in test 

water conditions, or as the result of surfactant use in the acute toxicity test. As quinclorac is an 

acid subject to dissociation in water, differences in water hardness may influence the toxicity of 

the compound. The available data suggest that quinclorac is more toxic to freshwater 

invertebrates in soft water (48-hour LC50= 28.9 mg/l in water 40-48 mg CaCO3/L) compared to 

harder water (21-day NOAEC 110 mg/l in water >150 mg CaCO3/L). An alternative explanation 

for the disparate toxicity results may be the presence of surfactant in the acute test, whereas no 

surfactant is evident for the chronic test. The use of the available 21-day chronic data as the 

toxicity endpoint for all freshwater systems represents an uncertainty. 

Table 13 Freshwater Invertebrate Chronic Toxicity Data (21-day life cycle test)

Species % Active 

Ingredient 

LOAEC 

 (mg/L) 

NOAEC (mg/L) MRID No. Classification 

Daphnia magna technical >110 110 44129202 acceptable 

LOAEC: Lowest observed adverse effect concentration 

NOAEC: No observed adverse effect concentration 

Estuarine and Marine Animal Acute Toxicity

Table 14 summarizes the data available for quinclorac effects on estuarine and marine animals. 

For the purposes of this risk assessment, the sheepshead minnow LC50 of > 94.4 mg/L will be 

used as the acute toxicity threshold for estuarine/marine fish and the mysid EC50 of 69.4 will 

serve as the threshold for estuarine/marine invertebrates. 

Table 14 Estuarine and Marine Animal Acute Toxicity Data

Species % Active 

Ingredient 

EC50/LC50 

(confidence limit) 

(mg/L) 

MRID No. Classification 

Sheepshead minnow 

Cyprinodon variegatus

96 >94.4 

(no mortality at 

highest dose) 

41063549 core 

Quahog clam 

Mercenaria mercenaria

96 >96.1 

(26% reduction in 

number of normal 

larvae at highest dose) 

41063552 core 

Mysid 

Mysidopsis bahia

96 69.4 (50.4-118) 41063553 core 

Blue crab 96 >94.4 41063551 supplemental* 
39

Callinectes sapidus (no mortality at 

highest dose) 

LC50: Lethal concentration to 50% of test population 

EC50: Effective concentration to 50% of test population 

NOAEC: No observed adverse effect concentration

*not listed acceptable test species

Estuarine and Marine Animal Toxicity from Chronic Exposure

No data are available for the toxicity of quinclorac to estuarine and marine animals following 

chronic exposures. 

Aquatic Plant Toxicity

Table 15 summarizes the available aquatic plant toxicity data for quinclorac 

Table 15 Aquatic Plant Toxicity Data

Species % Active 

Ingredient 

EC50

 (mg/L) 

NOAEC (mg/L) MRID No. Classification 

Freshwater diatom 

Navicula pelliculosa

96 >0.5 0.5 41063574 

Green alga 

Selenastrum 

capricornutum

96 >0.5 0.5 41063574 

Marine diatom 

Skeletonema 

costatum

96 >0.5 0.5 41063574 

Duckweed 

Lemna gibba

96 >0.5 0.5 41063574 

Bluegreen alga

Anabaena flosaquae 

96 >0.5 0.5 41063574 

acceptable

EC50: Effective concentration for 50% inhibition 

NOAEC: No observed adverse effect concentration
40

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

Table 16 identifies fate and ecological studies which are missing or are not acceptable, and may 

be requested to assess risk to the environment: 

Table 16 Preliminary Identification of Data Gaps for Fate and Ecological Assessment 

Fate and Ecological 

Taxa studies 

Description of study Projected status of data 

gap 

Basis for decision 

Chronic freshwater invertebrate Chronic freshwater invertebrate 

NOAEC value was greater than 

the acute LD50 value for 

freshwater aquatic invertebrates 

Study requested A new study is requested due to 

uncertainties with the NOAEC 

value which is greater than the 

acute LD50 value for freshwater 

aquatic invertebrates. 

 In addition, this study will be 

used to estimate chronic 

estuarine marine invertebrate 

toxicity 

Acute freshwater invertebrate Acute freshwater invertebrate 

study used a surfactant which it 

is uncertain that this surfactant 

effected the results of the 

toxicity test 

Study requested A new study is requested due to 

uncertainties with the LD 50 value 

which is less than the chronic 

NOAEC value for freshwater 

aquatic invertebrates. In addition, 

this study was based on a 

formulated product (quinclorac 

and surfactant). 

This study will be used to 

estimate chronic estuarine marine 

invertebrate toxicity 

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 

 

Estuarine/marine invertebrate Chronic study for 

estuarine/marine invertebrate 

was not submitted 

Study not requested Acute to chronic ratios will be 

sufficient to not request study 

pending a chronic freshwater 

invertebrate daphnia magna 

study based on TGAI . 

 
41

 Data on the degradates (BH514-

1 and BH 514 2-OH; >10% 

applied)) and one minor (BH514-

HMe-ester; 8% applied) to 

determine risks to groundwater 

The registrant claimed that 

studies performed later between 

1989 and 1990 in FL, WI, and 

NY showed no movement of 

quinclorac degradates below 

surface levels 

Studies requested The degradates (BH514-1 and 

BH 514 2-OH; >10% applied)) 

and one minor (BH514-HMeester; 8% applied) studies have 

not yet been received nor 

reviewed by EFED. Until these 

studies which were performed 

1989-1990 are submitted, 

reviewed, and deemed acceptable 

by the Agency, the above 

mentioned metabolites are 

considered potential 

contaminants of groundwater 

resources. 

Foliar dissipation residue data Foliar dissipation data studies or 

related data were not available 

 Study not requested Acute and chronic mammal 

exceedences did not occur with 

LD50 and NOAEC values. Acute 

avian LOCs occurred with the 

non-definitive LD50 of >1900 

mg/kg-bw. Fate studies indicate 

that half-lives may be greater 

than one year. 

 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. 

Small scale prospective 

groundwater contamination study 

Small scale prospective 

groundwater contamination study 

for the quinclorac under the 

expected conditions of the 

currently registered crops. 

Study requested Based on the environmental 

persistence of quinclorac, its 

potential to enter groundwater as 

modeled by SCI-GROW and 

indicated in terrestrial field 

studies, the potential for 

groundwater impacts to nontarget crops via contaminated 

groundwater a small scale 

prospective groundwater a 

contamination study for the 

compound under the expected 

conditions of use in wheat and 

sorghum is requested 

. 

 

 12. OPEN LITERATURE 

Previous assessments did not include open literature data as identified by ORD, MED ECOTOX 

literature search program. 

13. NEW ASSESSMENT DECISION 

EFED needs additional data (or will apply alternate effects assumptions) and would need to 

conduct new assessments for all registered outdoor uses. The new assessments are needed 

because of the following: 
42

(a) Some uses and application type scenarios were not assessed for ecological risk or 

 did not include current terrestrial or aquatic models. 

 

(b) Open literature data, as identified by ORD, MED ECOTOX literature search program, 

were not included in previous assessments. 

 

 (dc) A new drinking water assessment needs to be completed based on a 14 day interval 

 and aerial applications. 

14. SUMMARY OF RISK 

Summary of risks identified from previous assessments and anticipated risks for 

maximum use rate application scenarios. 

Estimated LOC exceedences for are summarized in Table 17 below. The risk conclusions are 

based on previously conducted risk assessments and anticipated exceedences for maximum use 

rates. The most recent comprehensive risk assessment was conducted on wheat and sorghum 

(1999). The most recent EUP was conducted on aquatic weed control in impounded waters 

(2007). The label maximum single application rates for quinclorac: (1) wheat and sorghum with 

a maximum seasonal rate of 0.75 lb ai /acre (2 applications @ 0.375lb ai/A, intervals were not 

included in terrestrial RQ calculations); (2) aquatic weed control with a maximum seasonal rate 

of 3.0 lb ai /acre. Acute dose based for avian exposure to quinclorac exceeded the LOCs with 

RQs ranging from 0.12- 0.83 for the both of the above application scenarios. Terrestrial plant 

RQs exceeded the LOCs for the wheat, sorghum and aquatic weed control application scenarios 

with RQs ranging 1 to 40. 

Nonvascular and vascular plants exceeded the LOCs for the aquatic weed control scenario with 

RQs exceedences of 1.0. LOCs were exceeded for acute mammalian exposure with the 

maximum RQ of 0.14 for aquatic weed control scenarios. Chronic LOCs were exceeded for 

mammals and birds for the aquatic weed control scenario with a maximum RQs of 1.95 

(mammals) and 1.4 (birds). 

 Anticipated LOCs are based on the maximum use and application rate for quinclorac for turf at 

1.50 lb ai/A (2 applications@ 0.75 lb ai/A and 14 day intervals). Anticipated LOC exceedences 

from the above maximum use rate are for acute birds (RQs 0.16- 0.37) and acute terrestrial plants 

(RQs 2.33- 95.63) for monocots and dicots. The acute avian LOC exceedence was based on the 

non-definitive LD50 value of >1900 mg/kg-bw. It is necessary that these exceedences derived 

from the non-definitive LD50 value of >1900 will be characterized with additional data in future 

assessments. No chronic avian LOC exceedences occurred with higher application rates. 
43

Aquatic EECs for the maximum application rates for labeled crops and additional GENEEC 

scenarios need to be determined. However, no acute or chronic exceedences are anticipated for 

aquatic fish or invertebrates. Uncertainty exists for chronic risks to estuarine marine 

invertebrates until further data is submitted. Chronic risks to estuarine marine fish will be 

estimated from acute to chronic ratios. LOC exceedences for aquatic plants based on direct 

application to impounded waters result in RQs of 1.0. 

Table 17 LOC Exceedences from Use on Wheat, Sorghum, Turf and Aquatic weed control. 

Use Endpoint Birds Mammals Terr. 

Plants 

Insect

s 

FW 

fish 

SW 

Fish 

FW 

Inverts 

SW 

Inverts 

Aquatic 

Plants 

Acute 

9 based 

on nondefinitive 

value 

 

9(listed 

and 

nonliste

d) 

 

Turf 

1.50 lb ai/A 

per season 

2application

s @0.75 per 

app, 14 day 

interval) Reproductive 

Acute 

9 based 

on nondefinitive 

value 

9(listed 

and 

nonliste

d) 

 

Wheat and 

sorghum 

0.75lb ai/A 

per season

1

Reproductive 

Acute 

9 based 

on nondefinitive 

value 

9

9(listed 

and 

nonliste

d) 

 9 (listed) 

Aquatic 

weed control 

3 lbs 

a.i./season1,2

Reproductive 9 9 1

All risk conclusions are based on previously conducted risk assessments Degradate toxicity was not 

 included. 

2

This EUP was based on aquatic weed control applied at 3lbs ai/season to reach a water concentration of 0.5mg/L 

9 Risk is anticipated to be > any of the Agency’s LOC 

 Blank cells indicate no LOC exceedences 

 

Aquatic Organisms 

Based on the (GENEEC) modeling, the 1999 risk assessment on turf showed no acute LOC 

exceedence for aquatic organisms. The highest modeled application rate scenario for the above 

crops was turf, which was based on 2 ground applications at a single rate of 0.375 lb ai/acre. 

The peak EEC is selected to represent exposures for acute effect risks. The 56-day and 21-day 

average EECs serve as the exposures for chronic effects to fish and invertebrates, respectively. 

Tables 18 to 22 summarizes the quinclorac RQs, EECs ((peak), (21-day), (56-day)) and the 

toxicity data used in the 1999 assessment on turf with ground and aerial applications. No acute 

or chronic LOCs were exceeded for the exposure scenarios assessed. There are no 
44

estuarine/marine organism toxicity data from chronic exposures available for use in calculating 

chronic risk quotients for these organisms. However, the similar acute sensitivities of these 

organisms to freshwater fish and invertebrates, coupled with the very low chronic risk quotients 

calculated for freshwater organisms; suggests that chronic risk concerns for estuarine and marine 

fish and invertebrates are likely to be minimal. 

Table 18 Acute and Chronic Risk Quotients for Freshwater Fish

Product1/ Application 

Method 

Peak 

EEC 

(μg/L) 

LC50

(μg/L) 

Acute RQ 

(Peak 

EEC/LC50) 

56-day 

EEC 

(μg/L) 

NOAEC 

(μg/L) 

Chronic RQ 

(56-d 

EEC/NOAEC) 

Paramount 40.28 31,600 0.0013 40.17 16,000 0.0025 TM/Aerial 

90 and 14-day 

intervals 40.28 31,600 0.0013 40.17 16,000 0.0025 

Paramount 40.20 31,600 0.0013 40.10 16,000 0.0025 TM/ 

Ground Spray 

90 and 14-day 

intervals 

40.20 31,600 0.0013 40.10 16,000 0.0025 

ParamountTM BW/ 

Aerial 1 application 

13.16 31,600 0.0004 13.11 16,000 0.0008 

ParamountTM BW/ 

Ground Spray 1 

application 

13.13 31,600 0.0004 12.10 16,000 0.0008

1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product.

Table 19 Acute and Chronic Risk Quotients for Freshwater Invertebrates

Product1/ Application 

Method 

Peak 

EEC 

(μg/L) 

LC50

(μg/L) 

Acute RQ 

(Peak 

EEC/LC50) 

21-day 

EEC 

(μg/L) 

NOAEC 

(μg/L) 

Chronic RQ 

(21-d 

EEC/NOAEC) 

Paramount 40.28 29,800 0.0014 40.23 110,000 0.0004 TM/Aerial 

90 and 14-day 

intevals 40.28 29,800 0.0014 40.23 110,000 0.0004 

Paramount 40.20 29,800 0.0013 40.16 110,000 0.0004 TM/ 

Ground Spray 

90 and 14 day 

intervals 

40.20 29,800 0.0013 40.16 110,000 0.0004 

ParamountTM BW/ 

Aerial 

13.16 29,800 0.0004 13.14 110,000 0.0001 
45

ParamountTM BW/ 

Ground Spray 

13.13 29,800 0.0004 13.12 110,000 0.0001

1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product. 

Table 20 Acute and Chronic Risk Quotients for Estuarine/Marine Fish

Product1/ Application 

Method 

Peak 

EEC 

(μg/L) 

LC50

(μg/L) 

Acute RQ 

(Peak 

EEC/LC50) 

56-day 

EEC 

(μg/L) 

NOAEC 

(μg/L) 

Chronic RQ 

(56-d 

EEC/NOAEC)2

Paramount 40.28 >94,400 <0.0004 40.17 no data -- TM/Aerial 

90 and 14-day intervals 

40.28 >94,400 <0.0004 40.17 no data -- 

Paramount 40.20 >94,400 <0.0004 40.10 no data -- TM/ 

Ground Spray 

90 and 14-day intervals 40.20 >94,400 <0.0004 40.10 no data -- 

ParamountTM BW/ 

Aerial 

13.16 >94,400 <0.0001 13.11 no data -- 

ParamountTM BW/ 

Ground Spray 

13.13 >94,400 <0.0001 12.10 no data -- 

1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

 2,4-D component of this product. 2

 -- lack of toxicity data precludes calculation of quotient 

Table 21 Acute and Chronic Risk Quotients for Estuarine/Marine Invertebrates

Product1/ Application 

Method 

Peak 

EEC 

(μg/L) 

LC50

(μg/L) 

Acute RQ 

(Peak 

EEC/LC50) 

21-day 

EEC 

(μg/L) 

NOAEC 

(μg/L) 

Chronic RQ 

(21-d 

EEC/NOAEC)2

Paramount 40.28 69,400 0.0006 40.23 no data -- TM/Aerial 

90 and 14-day intervals 

40.28 69,400 0.0006 40.23 no data -- 

Paramount 40.20 69,400 0.0006 40.16 no data -- TM/ 

Ground Spray 

90 and 14-day intervals 40.20 69,400 0.0006 40.16 no data -- 

ParamountTM BW/ 

Aerial 

13.16 69,400 0.0002 13.14 no data -- 

ParamountTM BW/ 

Ground Spray 

13.13 69,400 0.0002 13.12 no data -- 

1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

 2,4-D component of this product. 2

 -- lack of toxicity data precludes calculation of quotient 
46

Table 22 Aquatic Plant Risk Quotients

Product1/ Application 

Method 

Peak 

EEC 

(μg/L) 

Alga 

EC50

(μg/L) 

Lemna 

gibba 

EC50

(μg/L) 

Lemna 

gibba

NOAEC 

(μg/L) 

Algal 

RQ2

 

Acute 

Aquatic 

Vascular 

Plant RQ3 

Endangered 

Aquatic Plant 

RQ4

Paramount 40.28 >500 >500 500 <0.081 <0.081 0.0806 TM/Aerial 

90 and 14-day intervals 

40.28 >500 >500 500 <0.081 <0.081 0.0806 

Paramount 40.20 >500 >500 500 <0.080 <0.080 0.0804 TM/ 

Ground Spray 

90 and 14-day intervals 40.20 >500 >500 500 <0.080 <0.080 0.0804 

ParamountTM BW/ 

Aerial 

13.16 >500 >500 500 <0.026 <0.026 0.0263 

ParamountTM BW/ 

Ground Spray 

13.13 >500 >500 500 <0.026 <0.026 0.0263 

1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

 2,4-D component of this product. 2

 EEC/alga EC50 3

 EEC/Lemna gibba EC50 4

 EEC/Lemna gibba NOAEC

Terrestrial Organisms 

Risk Assessment for Nontarget Terrestrial Animals 

Avian Acute and Chronic Risks

The acute and chronic risk quotients for broadcast applications of quinclorac formulations are 

listed in Tables 23 and 24 based on the 1999 risk assessment for a single seasonal application 

rate of 0.25 lb ai/A and 0.75 lb ai/A . No levels of concern (LOCs) are exceeded under the 

exposure scenarios assessed. 
47

Table 23 Avian Acute Risk Quotients for Single Application of Quinclorac Products 

(Aerial and Ground Spray) Based on a Northern Bobwhite Quail LC50 of >5000 mg/kgdiet 

Product1 Application 

Rate 

(lbs ai/A) 

Food Items Maximum EEC 

(mg/kg-diet) 

LC50 (mg/kgdiet) Acute RQ 

(EEC/LC50) 

Short 

grass 

180 >5000 <0.036 

Tall 

grass 

82.5 >5000 <0.017 

Broadleaf 

plants/Insects 

101.3 >5000 <0.020 

ParamountTM 0.75 

per season 

Seeds 11.3 >5000 <0.002 

Short 

grass 

60.0 >5000 <0.012 

Tall 

grass 

27.5 >5000 <0.006 

Broadleaf 

plants/Insects 

33.8 >5000 <0.007 

ParamountTMDW 0.25 

 per season 

Seeds 3.8 >5000 <0.001 1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product.
48

Table 24 Avian Chronic Risk Quotients for Single Application of Quinclorac Products 

(Aerial and Ground Spray Based on a Northern Bobwhite Quail NOAEC of 500 mg/kgdiet)

Product1 Application 

Rate 

(lbs ai/A) 

Food Items Maximum 

EEC 

 (mg/kg-diet) 

NOAEC 

(mg/kg-diet) 

Chronic RQ 

(EEC/NOAEC) 

Short 

grass 

180 500 0.36 

Tall 

grass 

82.5 500 0.17 

Broadleaf 

plants/Insects 

101.3 500 0.20 

ParamountTM 0.75 per 

season 

Seeds 11.3 500 0.02 

Short 

grass 

60.0 500 0.12 

Tall 

grass 

27.5 500 0.06 

Broadleaf 

plants/Insects 

33.8 500 0.07 

ParamountTMBW 0.25 per 

season 

Seeds 3.8 500 0.01 1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product. 

Mammalian Acute and Chronic Risks

Mammalian acute risk quotients were calculated using the daily oral dose estimates for a 15 g 

mammal consuming 95% of its bodyweight as diet and the LD50 for laboratory rats. The results 

of these calculations are expressed in terms of LD50s per day. Table 25 summarizes the results 

of these risk quotient calculations. None of the acute risk quotient results exceed EFED levels of 

concern. 

 Mammalian chronic risk quotients were calculated using the daily oral estimates for the same 15 

g mammal and the daily oral dose corresponding to the NOAEL for reproduction effects in 

laboratory rats. Table 26 summarizes the results of these risk quotients calculations based on the 

1999 assessment. In all cases, except for consumption of short grass (RQ = 1.07), the EFED 

level of concern was not exceeded. 

 
49

Table 25 Mammalian Acute Risk Quotients for Application of Quinclorac Products 

(Aerial and Ground Spray Based on a Laboratory Rat LD50 of 2190 mg/kg-bw 

Product1

Application 

Rate 

(lbs ai/A) Food Items 

Daily Oral Dose 

(mg/kg-bw/day) 

LD50 

(mg/kg-bw) 

Acute RQ 

(LD50/day or 

Dose/LD50)

Short 

grass 

171.6 2190 0.08 

Tall 

grass 

78.7 2190 0.04 

Broadleaf 

plants/Insects 

96.5 2190 0.04 

ParamountTM 0.75 per 

season 

Seeds 10.7 2190 0.005 

Short 

grass 

57.2 2190 0.03 

Tall 

grass 

26.2 2190 0.01 

Broadleaf 

plants/Insects 

32.2 2190 0.01 

ParamountTMDW 0.25 per 

season 

Seeds 3.6 2190 0.002 1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product. 
50

Table 26 Mammalian Chronic (Reproduction) Risk Quotients for Application of 

Quinclorac Products (Aerial and Ground Spray Based on a Laboratory Rat NOAEL of 160 

mg/kg-bw/day

Product1 Application 

Rate 

(lbs ai/A) 

Food Items Daily Oral Dose 

(mg/kg-bw/day) 

NOAEL 

(mg/kg-bw/day) 

RQ 

(Dose/NOA

EL) 

Short 

grass 

171.6 160 1.07 

Tall 

grass 

78.7 160 0.49 

Broadleaf 

plants/Insects 

96.5 160 0.60 

ParamountTM 0.75 per 

season 

Seeds 10.7 160 0.067 

Short 

grass 

57.2 160 0.36 

Tall 

grass 

26.2 160 0.16 

Broadleaf 

plants/Insects 

32.2 160 0.20 

ParamountTMBW 0.25 per 

season 

Seeds 3.6 160 0.023 1

 Risks for ParamountTMBW are for the quinclorac component alone, no assessment has been performed for the 

2,4-D component of this product. 

Risks to Beneficial Insects

Currently, EFED has no procedure for assessing risk to nontarget insects. However, the results 

of acceptable toxicity studies are used for recommending appropriate label precautions. The 

relatively non-toxic nature of quinclorac with respect to honeybees suggests no concern that 

quinclorac will directly impact beneficial insects. 

15. RESIDUES OF QUINCLORAC IN WATER AND THE TERRESTRIAL 

ENVIRONMENT

 DRINKING WATER RESIDUE PROFILE

The Agency does not have monitoring data available to perform a quantitative drinking water 

risk assessment for quinclorac at this time 

A Tier II screening-level drinking water assessment for quinclorac (3,7-dichloro-8-

quinolinecarboxylic acid , BAS 514-H was provided in support of the new proposed uses of this 

herbicide to control broadleaf and grass weeds on residential/commercial turf grasses and on 

other turf grasses (picnic grounds, athletic field, and sod farms) (see September 13, 2007, 
51

Estimated Drinking Water Assessment for Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid, CAS# 

84087-01-4) Use on Turfgrasses DPBarcode: 341487) 

EFED believes that quinclorac has the potential for movement into ground water. Furthermore, 

since quinclorac is not tightly bound to soils, it could be available to run off in surface water as 

well as by erosion to surface waters. Tables 27 and 28 list the EDWCs of quinclorac residues in 

surface and ground water, respectively, as reported in the aforementioned drinking water 

assessment. These concentrations are based on the current environmental fate data for 

quinclorac, the maximum use rate from registered and proposed uses (Drive 75DF Herbicide 

label turf use, 2 to 3 applications of 0.25 – 0.75 lb ai/A/ appl at 21-day interval, not to exceed 1.5 

lb ai/A per year) and EFED aquatic models (PRZM/EXAMS for surface water and SCI-GROW 

for ground water. 

Quinclorac major degradation products such as BH 514-1 and BH 514 2-OH were not considered 

in this assessment. Although these degradates were detected in the laboratory studies, they seem 

to be intermediate degradates (see Environmental Fate section), and were not found in the 

terrestrial field dissipation studies at any significant levels (>10% of total applied). Furthermore, 

since quinclorac is persistent and mobile, it is expected to be the predominant residue in ground 

and surface waters. 

Table 27 – Surface Water DWECs for Quinclorac use on Turfgrasses, ground application 

Surface Water EWDCs (μg/L) 

Scenario 1 in 10 year annual 

peak 

(acute) 

1 in 10 year annual 

mean 

(chronic) 

30 year annual mean 

(cancer) 

PCA / CAF 1.00* 0.82** 1.00 0.82 1.00 0.82 

0.5 lb ai/A, 3 appl, 21 days 

apart 

PA Turf – pre emergence

PA Turf – post emergence

FL Turf – pre-emergence

FL Turf – post emergence

0.75 lb ai/A, 2 appl, 21 days 

apart 

PA Turf – post emergence

FL Turf – post emergence

17.5 

21.2 

17.9 

22.9 

22.5 

21.4 

14.3 

17.4 

14.7 

18.8 

18.5 

17.5 

 

12.3 

14.5 

10.7 

12.7 

14.2 

11.6 

10.1 

11.9 

8.8 

10.4 

11.6 

9.5 

8.7 

10.3 

6.3 

7.1 

9.9 

6.9 

7.1 

8.4 

5.2 

5.8 

8.1 

5.7

*Results with PCA of 1 can be used for other turf use, such as picnic grounds, athletic fields, sod farms, ... 

**Results adjusted with CAF of 0.82 represents the maximum percent treated on turf, residential and commercial use. This assumes four houses 

of 2000ft2

 each per acre and does not take into account driveway, sidewalk, or porches, ... 

Note that the EDWCs were estimated for both pre and post emergence uses for the 0.5 lb ai/A 

applications. The differences between the two sets of data result from the method of application (soil 

applied vs. foliar applied) and the application dates. Only post emergence uses are allowed for the 0.75 lb 

ai/A applications. 
52

Table 28 - Ground Water EDWCs for Quinclorac use on Turfgrasses (3 applications of 0.5 lb 

ai/A/application) 

Ground Water EDWCs (μg/L) (3 appl of 0.5 lb 

ai/A/appl) 

Ground Water EDWCs (μg/L) (2 appl of 0.75 lb 

ai/A/appl) 

29.0 

28.9 

The groundwater concentrations generated by SCI-GROW are based on the largest 90-day average 

recorded during the sampling period. Since there is relatively little temporal variation in groundwater 

concentrations compared to surface water, the concentration of 29μg/L can be considered as both the 

acute and chronic values. 

Although current uses also include aerial applications with an assumed shorter re-application interval (14 

days) on certain crops (sorghum, wheat, non agricultural rights of way/ fence row/ hedgerows, 

agricultural fallowland/idleland, grasses grown for seed), it is not expected that the EDWCs from these 

crops will exceed those reported from turf use as listed in above Tables 28 and 29. Granular 

applications do not need to be incorporated in the drinking water assessment because the 

application rates are less than ground and aerial spray applications. 

Chemical structures for quinclorac are summarized in Table 29. 
53

 Table 29 Chemical name and structure of quinclorac and its degradates BH514-1 and 

 BH5142-OH

Common Name Chemical Structure 

Quinclorac 

BH514-1 

 

 BH5142-OH 

Cl N

Cl

CO 2 H 

N

CO 2H

N

CO 2H

OH

Cl
54

Table 30 list all the current registrations and EUPs based on BEAD information 2007. 

Table 30 Current Registrations and EUPs for Quinclorac based on BEAD 

information (2007) 

Registration # Name Status Company Name

Percent 

Active 

Ingredient

228-423 DQD SELECTIVE 

HERBICIDE 

Conditionally 

Registered (06-

Apr-2005) 

NUFARM AMERICAS 

INC. 

7.91 

228-531 NUP 12D02 

HERBICIDE 

Conditionally 

Registered (24-

Aug-2007) 

NUFARM AMERICAS 

INC. 

8.25 

239-2689 LAWN CRABGRASS 

AND WEED KILLER 

Conditionally 

Registered (03-

Sep-2004) 

THE ORTHO 

BUSINESS GROUP 

0.1 

538-296 TURF BUILDER WITH 

WEED CONTROL III 

Conditionally 

Registered (09-

Dec-2002) 

SCOTTS COMPANY, 

THE 

0.52 

1381-209 QUINCLORAC 75 DF Registered (11-

Oct-2006) 

WINFIELD 

SOLUTIONS, LLC 

75 

2217-885 EH-1426 HERBICIDE Conditionally 

Registered (18-

Jan-2006) 

PBI/GORDON CORP 3.49 

2217-886 EH-1427 HERBICIDE Conditionally 

Registered (18-

Jan-2006) 

PBI/GORDON CORP 5.69 

2217-887 EH-1428 HERBICIDE Conditionally 

Registered (18-

Jan-2006) 

PBI/GORDON CORP 0.121 

2217-888 EH-1425 HERBICIDE Conditionally 

Registered (18-

Jan-2006) 

PBI/GORDON CORP 8.38 

2217-894 EH-1432 HERBICIDE Conditionally 

Registered (21-

Apr-2006) 

PBI/GORDON CORP 1.61 

2217-896 EH-1437 HERBICIDE Conditionally 

Registered (25-

Aug-2006) 

PBI/GORDON CORP 2.13 

2217-901 EH-1434 HERBICIDE Conditionally 

Registered (30-

Jan-2007) 

PBI/GORDON CORP 5.65 

2217-906 EH-1449 HERBICIDE Conditionally 

Registered (27-

Aug-2007) 

PBI/GORDON CORP 0.104 
55

7969-93 FACET 50 WP Conditionally 

Registered (13-

Oct-1992) 

BASF CORPORATION 50 

7969-109 QUINCLORAC 

MANUFACTURING 

USE PRODUCT 

Conditionally 

Registered (28-

Oct-1992) 

BASF CORPORATION 98 

7969-113 FACET 75 DF 

HERBICIDE 

Registered (09-

Nov-1994) 

BASF CORPORATION 75 

7969-130 DRIVE 75 DF 

HERBICIDE 

Conditionally 

Registered (09-

Nov-1998) 

BASF CORPORATION 75 

7969-152 PARAMOUNT BW 

HERBICIDE 

Conditionally 

Registered (04-

Jun-1999) 

BASF CORPORATION 15 

7969-158 FACET GR 

HERBICIDE 46 

Conditionally 

Registered (27-

Apr-1998) 

BASF CORPORATION 1.5 

7969-172 DRIVE 75 

MANUFACTURERS 

CONCENTRATE 

Conditionally 

Registered (10-

Dec-1998) 

BASF CORPORATION 75 

7969-222 CLEARPATH 

HERBICIDE 

Registered (12-

Jul-2004) 

BASF CORPORATION 61.98 

34704-920 QUINCLORAC 75DF 

HERBICIDE 

Conditionally 

Registered (03-

Mar-2006) 

LOVELAND 

PRODUCTS, INC. 

75 

42750-85 QUINCLORAC 

TECHNICAL 

Conditionally 

Registered (10-

Oct-2005) 

ALBAUGH INC 99 

42750-88 QUINCLORAC 75DF 

AG 

Conditionally 

Registered (10-

Oct-2005) 

ALBAUGH INC 75 

42750-90 QUINCLORAC 75DF 

SP 

Conditionally 

Registered (10-

Oct-2005) 

ALBAUGH INC 75 

42750-131 QUINCLORAC 75 

SWF 

Conditionally 

Registered (06-

Feb-2006) 

ALBAUGH INC 75 

71085-26 RICEPRO Registered (13-

Mar-2007) 

RICECO LLC 2 

73220-15 QUALI-PRO 

QUINCLORAC 75 

Registered (02-

Oct-2007) 

FARMSAVER.COM, 

LLC 

75 

79676-22 QUINCLORAC G-PRO 

75 DF 

Conditionally 

Registered (14-

Dec-2005) 

GRO-PRO, LLC 75 
56

81927-21 ALLIGARE 

QUINCLORAC 75 

WDG 

Registered (18-

Oct-2007) 

ALLIGARE, LLC 75 

AR070006 RICEPRO Under Review 

(07-May-2007) 

RICECO LLC 2 

UT990003 FACET 75 DF 

HERBICIDE 

Registered (20-

Sep-1999) 

BASF CORPORATION 75 

7969-EUP-25 Issued (20-

Mar-1991) 

BASF CORPORATION 100 

7969-EUP-27 Issued (14-Jan1991) BASF CORPORATION 50 

7969-EUP-29 Issued (22-

May-1991) 

BASF CORPORATION 50 

7969-EUP-40 Issued (23-

May-2007) 

BASF CORPORATION 75 

98ND20 Issued (19-Sep1998) ND Dept. of Agriculture 

98NE07 Issued (25-Jun1998) NE Department of 

Agriculture 

 
57

V. Human Health Effects Scoping Document

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460

OFFICE OF 

PREVENTION, PESTICIDES AND 

TOXIC SUBSTANCES

MEMORANDUM

Date: September 26, 2007 

SUBJECT: Quinclorac (PC code 128974). Human Health Risk Problem Formulation Document in Support 

of Registration Review. DP Barcode 344486. 

FROM: Yan Donovan, Risk Assessor 

 Health Effects Division (7509P) 

 Office of Pesticide Programs 

THRU: Ray Kent, Branch Chief 

 Susan Hummel, Senor Scientist 

 Reregistration Action Branch 4 

 Health Effects Division (7509P) 

 Office of Pesticide Programs 

TO: Sherrie Kinard 

 Chemical Review Manager 

 Special Review and Reregistration Division (7508P) 

 Office of Pesticide Programs 

Executive Summary 

Attached is Health Effects Division’s (HED) human health risk assessment status update for 

quinclorac as part of the Registration Review process. Quinclorac is a systemic herbicide 

currently registered for use on rice, sorghum, and wheat. It is also registered for use on 

residential lawns, ornamentals, and turf grass. The most recent comprehensive risk assessment 

for quinclorac was conducted in association with the establishment of import tolerance on barley 

(September, 2007). The toxic effects being regulated are developmental effects such as 

increased resorptions and post-implantation loss, decreased number of live fetuses, and reduced 

fetal body weight. Chronic effects include decreased body weights. Based on the 2005 

Guidelines for Carcinogen Risk Assessment, quinclorac was tentatively classified as "Not likely 
58

to be carcinogenic to humans" since only benign tumors were seen in only one sex and in one 

species. Aggregate risk assessments included dietary exposure (food + water) and residential 

post-application exposure from use on grass. Risk estimates were based on conservative, healthprotective assumptions and the resulting aggregate risk estimates are not of concern. Neither 

residential handler nor occupational risks were assessed. 

HED’s problem formulation conclusions are: 1) The toxicology endpoint selections are adequate. 

However, the toxicology database for quinclorac is incomplete at this time. A 90-day inhalation 

toxicity study in the rat is required to assess inhalation exposure from spray uses. 2) The dietary 

exposure database is complete. However, the newly submitted aspirated grain fraction (AGF) 

studies on wheat and sorghum have not been reviewed. A full review of these AGF studies is 

needed. AGF and livestock tolerances may need to be revised based on the review of the AGF 

studies. The drinking water assessment is adequate. The dietary exposure assessment (included 

food and water) is adequate. 3) The residential post application exposure assessment is adequate. 

However, no residential handler risks were assessed; therefore, a new residential handler 

assessment is needed for the Registration Review of quinclorac. 4) Aggregate risk assessment is 

adequate. 5) No occupational risk assessments have been conducted before. A new occupational 

assessment is required for Registration Review. 
59

Introduction 

HED has evaluated the existing human health risk assessments for quinclorac to determine 

whether sufficient data are available and whether a new human health risk assessment is needed 

to support Registration Review. HED has considered the most recent risk assessments for 

quinclorac (HED memo of 9/13/2007, M. Doherty, D325790, and HED memo of 12/15/98, M. 

Nelson, D238399), updates to its toxicity, exposure and usage databases, information available 

through HED and OPPIN database, literature search, and current Agency science policies and 

risk assessment methods. Quinclorac is a persistent and mobile, systemic herbicide currently 

registered for use on weed control in rice, sorghum, and wheat. It is also registered for use on 

residential lawns, ornamentals, and turf grass. The mechanism of action of herbicidal effects is 

not completely understood. Permanent tolerances are currently established for parent quinclorac 

per se in/on rice, sorghum, wheat, and livestock commodities [40 CFR 180.463]. Some 

quinclorac products also contain other active ingredients such as 2,4-dichlorophenoxyacetic acid 

[2,4-D]. The problem formulation conducted in this review is for quinclorac only. 

Chemical Identity 

Table 1. Quinclorac Nomenclature

Chemical structure 

Cl N

O OH

Cl

Common name Quinclorac 

Empirical formula C10H5Cl2NO2

Molecular weight 242.1 

PC Code 128974 

IUPAC name 3,7-dichloroquinoline-8-carboxylic acid 

CAS name 3,7-dichloro-8-quinolinecarboxylic acid 

CAS registry number 84087-01-4 

 

Hazard Identification/Toxicology 

Quinclorac (technical grade material) has a low order of acute toxicity as demonstrated by 

classification into Toxicity Category III by the oral, dermal, and inhalation routes. The chemical 

is a mild eye irritant, is not a skin irritant, but was positive for dermal sensitization. Subchronic 

toxicity includes decreased body weight gains, increased water intake, increased liver enzymes 

and focal chronic interstitial nephritis. Chronic toxic effects include body weight decrement, 

increase in kidney and liver weights, and hydropic degeneration of the kidneys. At high doses, 

chronic toxicity also includes increased incidences of pancreatic acinar cell hyperplasia and 

adenomas. Developmental toxicities include increased resorptions, post-implantation loss, 

decreased number of live fetuses, and reduced fetal body weight. These effects occurred at much 
60

higher dose than the maternal effects which demonstrated by increased mortality, decrease in 

food consumption and increase in water consumption, decreased body weight gain, clinical signs 

of reduced defecation, diarrhea, apathy, and poor general state. Because there is no evidence of 

neurotoxic effects, no acute, subchronic, or developmental neurotoxicity studies are required. 

Evaluated under the 2005 Guidelines for Carcinogen Risk Assessment, quinclorac was 

tentatively classified as "Not likely to be carcinogenic to humans" since only benign tumors were 

seen in only one sex and in one species. The chronic RfD would adequately account for all 

chronic effects, including the observed adenomas, likely to result from exposure to quinclorac. 

The acute dietary endpoint was based on developmental toxicity, while the chronic dietary 

endpoint was based on decreased body weight in the 18-month carcinogenicity study. No data 

were available on the inhalation toxicity of quinclorac. Inhalation endpoint was based maternal 

toxicity from the rabbit developmental study and assuming inhalation absorption of 100%. 

The FQPA Safety Factor was reduced from 10X to 1X for infants and children based upon the 

fact that the toxicology database for quinclorac is complete and there is no indication of 

increased susceptibility of rat or rabbit fetuses to in utero and/or postnatal exposure in the 

developmental and reproductive toxicity data. A summary of the toxicological endpoint 

decisions from the most recent human health risk assessment of quinclorac is given in Appendix 

A. 

Conclusions: The HED Registration Review problem formulation team has re-evaluated the 

above toxicity endpoints and dose response according to the current policies. HED concluded 

that the endpoint selections in the most recent risk assessment are adequate. A 28-day 

subchronic inhalation study is recommended. 

Dietary Exposures 

The residue of concern in food and water was determined to be quinclorac per se. The estimated 

drinking water concentration (EDWC) from groundwater (29 μg/L) was used in the dietary 

assessment as these are greater than the surface water values. Since there is relatively little 

temporal variation in groundwater concentrations compared to surface water, the concentration 

(29 ug/L) was used for both acute and chronic exposure assessment. Acute and chronic 

aggregate dietary (food + drinking water) exposure were conducted using the Dietary Exposure 

Evaluation Model DEEM-FCIDTM, Version 2.03 which use food consumption data from the 

U.S. Department of Agriculture’s Continuing Surveys of Food Intakes by Individuals (CSFII) 

from 1994-1996 and 1998. Both the acute and chronic dietary assessment are based on 

tolerance-level residues for all agricultural commodities, assume 100% crop treated, use DEEM 

7.81 default processing factors, and directly incorporate modeled quinclorac EDWCs. 

The acute assessment provides a risk estimate of < 1% of the acute population-adjusted dose 

(aPAD) at the 95th percentile of exposure for females 13-49 years of age. Risk estimates for the 

chronic assessment vary by population group and range from < 1% of the chronic PAD (cPAD) 

to 2% of the cPAD. 

Conclusions: The residue chemistry database is complete with the newly submitted AGF 

studies. These new studies have not been reviewed. A review of these studies is needed. 

Existing AGF tolerance was previously determined by applying the maximum theoretical 

concentration factor (200X) to the proposed tolerance (6 ppm) on grain sorghum grain which is 
61

1200 ppm. The new AGF tolerance will likely be a lot lower based on the new AGF studies 

and as a result, the animal dietary burden will likely be lower, hence the residues in meat and 

meat byproducts will likely be lower as well. Revisions to the existing AGF and livestock 

tolerances may be needed. The drinking water assessment is adequate. The dietary exposure 

assessment is also adequate. No new dietary assessment is needed. 

Residential Exposure 

Based on the registered use pattern, there are residential handler and residential post application 

exposure scenarios. Post-application incidental oral (hand-to-mouth, object-to-mouth, and soil 

ingestion) exposures were evaluated using the maximum application rates (0.0172 lb ai per 1000 

sq ft). The combined MOE (5,000) is greater than 100 and, therefore, is not of concern to HED. 

Conclusions: The post-application exposure assessments are adequate. However, no residential 

handler assessment was conducted. A new residential handler assessment is needed for the 

Registration Review of quinclorac. 

Aggregate 

Aggregate risk assessments were conducted for acute, chronic, and short-term. There is no risk 

for concern. 

Conclusions: HED problem formulation team concluded that the most recent aggregate risk 

assessment is adequate. No new aggregate risk assessment is needed for the Registration Review 

of quinclorac. 

Occupational Exposure 

There are occupational exposure scenarios based on the use patterns. However, no occupational 

risk assessments have been conducted before. A new occupational assessment is required for the 

Registration Review once the inhalation endpoint is selected. 

Incident Report 

No incident report has been generated for quinclorac. A new incident report is needed with the 

Registration Review. 

Cumulative 

Quinclorac has not been identified as a member of common mechanism group; therefore, 

accumulative assessment has not been conducted for quinclorac. 

Human Studies 

No human studies were used in either hazard or exposure assessment. 

Codex MRLs 
62

No Codex or Mexico MRLs are reported. The U.S. tolerances on livestock fat and meat 

byproducts are not harmonized with Canada MRLs (see Appendix B for details). Future work is 

needed to harmonize these tolerances. 

Conclusions/Future Actions Needed 

Below are the detailed actions needed in the future Registration Review for quinclorac: 

Exposure

The 1998 risk assessment indicated the need for data on aspirated grain fractions as a data gap 

in the residue chemistry database, and submission of such data should be made a condition of 

registration. Since then, residue data on wheat and sorghum aspirated grain fractions have 

been submitted but not been reviewed. They are: 

45598703 Haughey, D.; Abdel-Baky, S.; Daussin, S. (2000) Magnitude of BAS 514 H 

Residues in Wheat Aspirated Grain Fraction: Lab Project Number: 2000/5187: 59553. 

Unpublished study prepared by BASF Corp. 61 p. {OPPTS 860.1500}. 

45598704 Haughey, D.; Daussin, S. (2000) Magnitude of BAS 514 H Residues in Sorghum 

Aspirated Grain Fraction: Lab Project Number: 59552: 2000/5186. Unpublished study prepared 

by BASF Corp. 61 p. {OPPTS 860.1500}. 

Tolerances on AGF and livestock commodities may need to be revised based on the review of 

the above studies. 

A residential handler assessment is needed. 

Occupational Exposure and Risk

A new occupational assessment is needed. 

Incident Report

A new incident report is needed. 

Data Requirements 

A 28-day subchronic inhalation study is recommended. 

References 

1) HED memo of 9/13/07, M. Doherty, D325790; 

2) HED memo of 12/15/98, M. Nelson, D238399; 

3) Bibliography for Quinclorac (OPPIN database). 
63

Appendix A

Summary of Toxicological Doses and Endpoints from the Most Recent Risk Assessment. 

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/FQPA 

Safety Factors 

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment 

Study and Toxicological Effects 

Acute Dietary 

(General 

Population, 

including 

Infants and 

Children) 

Not applicable. An endpoint for acute dietary exposure to the general population was not selected 

because there was no available endpoint that was appropriate for this scenario (effects observed in the 

available studies are presumed to require more than one exposure). 

Acute Dietary 

(Females 13-

49 years of 

age) 

NOAEL 

(developmental) 

= 200 mg/kg/day 

UFA= 10x 

UFH=10x 

FQPA SF= 1x 

Acute 

NOAEL = 

200 

mg/kg/day 

aPAD = 2.0 

mg/kg/day 

Developmental toxicity study in rabbits 

Developmental toxicity LOAEL = 600 

mg/kg/day based on increased early 

resorptions and postimplantation loss, 

decreased live fetuses, decreased fetal 

weight. These fetal effects are presumed to 

occur after a single dose. 

Chronic 

Dietary (All 

Populations) 

NOAEL= 37.5 

mg/kg/day 

UFA= 10x 

UFH=10x 

FQPA SF= 1x 

Chronic 

NOAEL = 

37.5 

mg/kg/day 

cPAD = 

0.38 

mg/kg/day 

Dietary carcinogenicity study in mice 

LOAEL = 150 mg/kg/day based on 

decreased body weight. 

Incidental 

Oral ShortTerm (1-30 

days) and 

IntermediateTerm (1-6 

months) 

NOAEL= 70 

mg/kg/day 

UFA= 10x 

UFH=10x 

FQPA SF= 1x 

Residential 

LOC for 

MOE = 100 

Developmental toxicity study in rabbits. 

Maternal toxicity LOAEL = 200 mg/kg/day 

based on decreased maternal body weight 

gain and food consumption (and increased 

water consumption). 

Dermal (all 

durations) 

Not applicable. A dermal endpoint was not selected because an appropriate endpoint was not available 

(no dermal toxicity at limit dose of 1000 mg/kg/day in a 21-day dermal toxicity study). 

Inhalation 

Short-Term 

(1-30 days) 

and 

IntermediateTerm (1-6 

months) 

NOAEL= 70 

mg/kg/day 

[Inhalation 

absorption rate = 

100% relative to 

oral absorption] 

UFA= 10x 

UFH= 10x 

FQPA SF= 1x 

Residential 

LOC for 

MOE = 100 

Developmental toxicity study in rabbits. 

Maternal toxicity LOAEL = 200 mg/kg/day 

based on decreased maternal body weight 

gain and food consumption (and increased 

water consumption). 

(Supported by subchronic and chronic 

dietary data on mice). 

Inhalation 

Long-Term 

(>6 months) 

Not applicable. Long-term inhalation exposure is not anticipated under current use scenarios. 
64

Summary of Toxicological Doses and Endpoints from the Most Recent Risk Assessment. 

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/FQPA 

Safety Factors 

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment 

Study and Toxicological Effects 

Cancer (oral, 

dermal, 

inhalation) 

Available carcinogenicity studies indicate that there was equivocal evidence of an increase in the 

incidence of pancreatic acinar cell adenomas in the male rat, but no treatment-associated increases in 

tumors were observed in female rats or in mice. A quantification of cancer risk is not warranted because 

the chronic RfD of 0.4 mg/kg/day is approximately 1200-fold lower than the dose (487 mg/kg/day) that 

induced the benign pancreatic tumors. Thus, the chronic RfD will adequately account for all chronic 

effects, including the observed adenomas, likely to result from exposure to quinclorac. If quinclorac is 

evaluated under the current 2005 Guidelines for Carcinogen Risk Assessment, quinclorac will be 

classified as "Not Likely to be Carcinogenic to Humans" since only benign tumors were seen in only one 

sex and in one species.

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = 

uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). UFL = use of a LOAEL to extrapolate a 

NOAEL. UFS = use of a short-term study for long-term risk assessment. UFDB = to account for the absence of key 

date (i.e., lack of a critical study). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c 

= chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not applicable. 
65

Appendix B 

Quinclorac 

US Canada Mexico Codex 

Residue Definition: 

Quinclorac (3,7-dichloro-8-quinoline carboxylic 

acid) 

40CFR180.463 

3,7-

dichloroquinolin8- 

carboxylic acid 

none none 

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

Cattle, fat 0.7 0.05 

Cattle, meat byproducts 1.5 0.05 

Cattle, meat 0.05 0.05 

Egg 0.05 0.05 

Goat, fat 0.7 0.05 

Goat, meat byproducts 1.5 0.05 

Goat, meat 0.05 0.05 

Grain, aspirated fractions 1200 - 

Hog, fat 0.7 0.05 

Hog, meat byproducts 1.5 0.05 

Hog, meat 0.05 0.05 

Horse, fat 0.7 0.05 

Horse, meat byproducts 1.5 0.05 

Horse, meat 0.05 0.05 

Milk 0.05 0.05 

Poultry, fat 0.05 0.05 

Poultry, meat byproducts 0.1 0.05 

Poultry, meat 0.05 0.05 

Rice, bran 15.0 - 

Rice, grain 5.0 5 

Rice, straw 12.0 - 

Sheep, fat 0.7 0.05 

Sheep, meat byproducts 1.5 0.05 

Sheep, meat 0.05 0.05 

Sorghum, grain, forage 3.0 - 

Sorghum, grain, grain 6.0 - 

Sorghum, grain, stover 1.0 - 

Wheat, forage 1.0 - 

Wheat, germ 0.75 - 

Wheat, grain 0.5 0.5 

Wheat, hay 0.5 - 

Wheat , straw 0.1 - 

Barley 2.0 2.0