UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

MEMORANDUM

Date: November 6, 2012

SUBJECT: Quinclorac: Risk Assessment In Support of Registration Review and for New 

Proposed Use on Rhubarb and Berry, low growing, except Strawberry, Subgroup 

13-07H.

PC Code: 128974, 028974 DP Barcode: D404794, D404808

Decision No.: 459055, 468877 Registration No.: NA

Petition No.: 1E7957 Regulatory Action: Section 3 Registration 

and Registration Review

Risk Assessment Type: Single Chemical/

Aggregate

Case No.: 7222

TXR No.: NA CAS No.: 84087-01-4, 84087-48-9

MRID No.: NA 40 CFR: 180.463

FROM: Jessica Kidwell, Risk Assessor

Abdallah Khasawinah, Ph.D., Toxicologist

Susan Hummel/Gary Otakie, Chemists

Bonnie Cropp-Kohlligian, Dietary Exposure Assessor

Ivan Nieves, ORE Assessor

Risk Assessment Branch IV, Health Effects Division (7509P)

THROUGH: Elissa Reaves, Ph.D., Branch Chief

Risk Assessment Branch IV

Health Effects Division (7509P)

TO: Wilhelmena Livingston, RM60

Risk Management and Implementation Branch 4

Pesticide Re-Evaluation Division (7508P)

Erik Kraft and Kable Davis, PM25

 Herbicide Branch, Registration Division (7505P)

Barbara Madden, PM5

RIMUERB, Registration Division (7505P)
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This document provides the Health Effect Division’s (HED’s) risk assessment on quinclorac 

conducted in support of registration review of currently registered uses including the use of 

quinclorac dimethyl amine, as well as the Albaugh Inc. and the Interregional Research Project 

No. 4 (IR4) request for proposed uses of the product QUINCLORAC 4L AG Herbicide (EPA 

Reg. No. 42750-169). Registration is proposed for QUINCLORAC 4L AG Herbicide with the 

active ingredient quinclorac on rhubarb and berry, low growing, except strawberry, subgroup 13-

07H.
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Table of Contents

1.0. Executive Summary............................................................................................................. 5

2.0. HED Recommendations ...................................................................................................... 8

2.1. Data Deficiencies ............................................................................................................. 9

2.2. Tolerance Considerations................................................................................................. 9

2.2.1. Enforcement Analytical Method............................................................................... 9

2.2.2. Recommended Tolerances........................................................................................ 9

2.2.3. Revisions to Petitioned-For Tolerances.................................................................. 12

2.2.4. International Harmonization ................................................................................... 13

2.3. Label Recommendations................................................................................................ 13

2.3.1. Recommendations from Residue Chemistry Reviews............................................ 13

2.3.2. Recommendations from Occupational Assessment................................................ 13

2.3.3. Recommendations from Residential Assessment ................................................... 13

3.0. Introduction........................................................................................................................ 13

3.1. Chemical Identity ........................................................................................................... 13

3.2. Physical/Chemical Characteristics................................................................................. 14

3.3. Pesticide Use Pattern...................................................................................................... 15

3.4. Anticipated Exposure Pathways ........................................................................................ 21

3.5. Consideration of Environmental Justice ........................................................................ 21

4.0. Hazard Characterization and Dose-Response Assessment................................................ 22

4.1. Toxicology Studies Available for Analysis ................................................................... 22

4.2.1. Dermal Absorption.................................................................................................. 23

4.4. Safety Factor for Infants and Children (FQPA Safety Factor)....................................... 24

4.4.1. Completeness of the Toxicology Database............................................................. 24

4.5. Toxicity Endpoint and Point of Departure Selections.................................................... 25

4.5.1. Dose-Response Assessment.................................................................................... 25

4.5.2. Recommendation for Combining Routes of Exposures for Risk Assessment........ 26

4.5.3. Cancer Classification and Risk Assessment Recommendation.............................. 26

4.5.4. Summary of Points of Departure and Toxicity Endpoints Used in Human Risk 

Assessment............................................................................................................................ 26

4.6. Incident Reports ............................................................................................................. 29

5.0. Dietary Exposure and Risk Assessment ............................................................................ 31

5.1. Metabolite/Degradate Residue Profile ........................................................................... 31

5.1.1. Summary of Plant and Animal Metabolism Studies............................................... 31

5.1.2. Summary of Environmental Degradation ............................................................... 33

5.1.3. Comparison of Metabolic Pathways....................................................................... 34

5.1.4. Residues of Concern Summary and Rationale........................................................ 34

5.2. Food Residue Profile...................................................................................................... 34

5.3. Water Residue Profile .................................................................................................... 37

5.4. Dietary Risk Assessment................................................................................................ 40

5.4.1. Description of Residue Data Used in Dietary Assessment..................................... 40
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5.4.2. Percent Crop Treated Used in Dietary Assessment ................................................ 41

5.4.3. Acute Dietary Risk Assessment.............................................................................. 41

5.4.4. Chronic Dietary Risk Assessment .......................................................................... 41

5.4.5. Cancer Dietary Risk Assessment............................................................................ 42

5.4.6. Summary Table....................................................................................................... 42

6.0. Residential (Non-Occupational) Exposure/Risk Characterization .................................... 43

6.1. Residential Handler Exposure........................................................................................ 43

6.2. Residential Post-Application Exposure.......................................................................... 45

6.2.3. Residential (Non-occupational) post-application inhalation ...................................... 45

6.2.4. Residential (Non-Occupational) Post-Application Dermal and Incidental Oral ........ 45

6.3. Combined Residential Risk Estimates (Multiple Exposure Scenarios)......................... 46

6.4. Residential Risk Estimates for Use in Aggregate Assessment ...................................... 46

6.5. Residential Bystander Post-application Inhalation Exposure............................................ 47

6.6. Spray Drift ......................................................................................................................... 47

7.0. Aggregate Exposure/Risk Characterization....................................................................... 48

7.1. Acute Aggregate Risk......................................................................................................... 48

7.2. Short-Term Aggregate Risk................................................................................................ 48

7.3. Intermediate-Term Aggregate Risk .................................................................................... 49

7.4. Chronic Aggregate Risk...................................................................................................... 49

7.5. Cancer Aggregate Risk ....................................................................................................... 50

7.6. Cumulative Exposure/Risk Characterization...................................................................... 50

8.0. Occupational Exposure/Risk Characterization .................................................................. 50

8.1. Short-/Intermediate-/Long-Term/Cancer (if needed) Handler Risk.................................... 50

8.2. Short-/Intermediate-/Long-Term/Cancer (if needed) Post-Application Risk...................... 57

8.2.1. Dermal Post-application Risk........................................................................................... 57

8.2.2. Inhalation Post-application Risk....................................................................................... 57

9.0. References.......................................................................................................................... 58

Appendix A. Toxicology Profile and Executive Summaries....................................................... 60

A.1 Toxicology Data Requirements...................................................................................... 60

A.2 Toxicity Profiles............................................................................................................. 61

A.3 Hazard Identification and Endpoint Selection ............................................................... 65

A.4 Executive Summaries..................................................................................................... 69

Appendix B. Review of Human Research ................................................................................... 78

Appendix C: International Residue Limits................................................................................... 79
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1.0. Executive Summary

Quinclorac is an herbicide for the selective post-emergent control of various annual grasses and 

broadleaf weeds. It is adsorbed via the root system and partially through the foliage and acts as 

an inhibitor of cell wall synthesis. Quinclorac is currently formulated into a variety of product 

formulations including; dry flowable, wettable powder, ready-to-use, granular, emulsifiable

concentrate, flowable concentrate, and liquid formulations. Two new agricultural uses of 

quinclorac have been proposed for the dry flowable formulation of the end-use product 

QUINCLORAC 4L AG Herbicide (EPA Reg. No. 42750-169), a 3.8 lb a.i./gallon liquid 

formulation. The new uses include the following crops; low growing berries, except 

strawberries, subgroup 13-07H, and rhubarb. The maximum single application rates for the 

proposed uses are 0.25 and 0.37 lb ai/A for low growing berries, except strawberries, subgroup 

13-07H, and rhubarb, respectively. QUINCLORAC 4L AG Herbicide may be applied as a foliar 

spray using ground equipment only. 

The variety of end-use products containing quinclorac is currently registered on rice, sorghum, 

and wheat. In addition to agricultural crops, quinclorac is also registered for: agricultural 

fallow/idleland/conservation reserves; nonagricultural uncultivated areas/soils; grass 

forage/fodder/hay; grasses grown for seed; pastures and rangelands; agricultural and 

nonagricultural rights of way/fencerows/hedgerows; agricultural uncultivated areas; utility

poles/rights of way; airports/landing fields; ornamental sod farms; commercial/industrial lawns. 

Additionally, quinclorac is registered for use by commercial applicators and homeowners on 

lawns, parks, in and around ornamentals, and golf courses.

A new physical form of quinclorac (EPA Reg. No. 7969-272) has recently been registered: Drive 

XLR-8 (Reg. No 7969-272), Paramount L Herbicide (Reg. No. 7969-315), Facet L Herbicide 

(EPA Reg. No. 7969-316), and Quinclorac 1.5 DMA (Reg. No 42750-224). These products are 

DMA (dimethylamine) salt forms of quinclorac. These products were not proposed for the new 

uses of quinclorac, proposed in the current petition, but are registered for use on rice and 

ornamental turf. 

Hazard

Quinclorac toxicity in experimental animals is observed mostly at doses above 150 mg/kg/day

following subchronic and chronic exposures. Subchronic exposure to quinclorac caused 

decreased body weight gains, increased water intake, increased liver enzymes and focal chronic 

interstitial nephritis (rats). Chronic toxic effects include body weight decrement, increase in 

kidney and liver weights, and hydropic degeneration of the kidneys (dogs). At high doses, 

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

adenomas. Neurotoxic effects were not observed in any of the acute, subchronic and chronic 

studies with quinclorac. There was no increased qualitative or quantitative fetal or offspring 

susceptibility in the prenatal developmental studies in rats or rabbits or postnatal reproduction

study in rats. 

There are no mutagenicity concerns. Quinclorac was classified in 1992 by the HED Cancer Peer 

Review committee (CPRC) as a group D carcinogen - not classifiable as to human 

carcinogenicity- based on recommendation by the EPA Scientific Advisory Panel. Based on the 

classification, a quantification of cancer risk is not warranted because the chronic RfD will 
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adequately account for all chronic effects, including carcinogenicity, that may result from 

exposure to quinclorac.

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

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.

Endpoints and Uncertainty Factors for Risk Assessment

HED reviewed the toxicity database for quinclorac as well as the most recent risk assessment

(D359759, Y. Donovan et al, 8/5/2009) and concluded that no changes in the points of departure 

(PODs) or FQPA SF (1x) are warranted. Since the last risk assessment the immunotoxicity study

in mice was submitted and reviewed. The results of this study did not impact the overall risk 

assessment. Since the last risk assessment, the HED Hazard and Science Policy Council 

(HASPOC) waived the requirement for a neurotoxicity battery (acute and subchronic

neurotoxicity studies) and a DNT study.

Chemistry

Permanent tolerances have been established for residues of quinclorac per se in/on barley, rice, 

sorghum and wheat at levels ranging from 0.1 ppm in wheat straw to 1200 ppm in aspirated grain 

fractions [40 CFR §180.463(a)]. Permanent tolerances have also been established for residues of 

quinclorac, per se, in/on livestock commodities at levels ranging from 0.05 to 1.5 ppm. In

addition, there is a tolerance for quinclorac residues on cranberry in §180.463(b), as a result of a 

Section 18 emergency exemption at 15 ppm.

The Inter Regional Project No. 4 (IR-4) has submitted a request for tolerances and registration of 

quinclorac on low growing berries, except strawberries, subgroup 13-07H, and rhubarb. 

Tolerances were proposed for residues of quinclorac in low growing berries, except strawberries, 

subgroup 13-07H, at 1.1 ppm, and rhubarb at 0.4 ppm.

The qualitative nature of quinclorac residues in plants was considered adequately understood for 

the currently registered crops, based upon the metabolism studies on rice, sorghum, and wheat. 

Further metabolism data may be needed if uses are further expanded. The qualitative nature of 

quinclorac residues in livestock is also understood based upon the adequate goat and poultry

metabolism studies. The Agency had concluded that parent is the only residue of concern in 

both plant and livestock commodities for purposes of the tolerance expression and risk 

assessment. 

An adequate enforcement method is available for enforcing quinclorac tolerances on plants and 

livestock, a GC/ECD method that uses methylation with diazomethane. There is available FDA 

multi-residue method (MRM) testing data that indicate that quinclorac is completely recovered 

using Protocol B. 

Adequate cattle and poultry feeding studies are available and support the use of quinclorac.

Adequate rotational crop studies are available and support the use of quinclorac.
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Dietary (food+water) Exposure and Risk

The Environmental Fate and Effects Division (EFED) completed a drinking water assessment in 

support of human health risk assessment. The current assessment is performed according to 

current EFED guidance and up-to-date models including the Tier II surface water model 

(PRZM/EXAMS) for all uses of quinclorac, except cranberries and rice. Screening-level Tier I 

modeling was used to estimate surface water concentrations for use on cranberry (provisional 

cranberry model) and rice (Tier I rice model) because the current Tier II model is not 

parameterized for those uses. The Tier I SCI-GROW model was used to estimate groundwater 

concentrations for all uses. Surface water EDWCs (acute = 511 μg/L and chronic = 511 μg/L) 

resulting from use on rice supersede previously recommended EDWCs. The recommended 

groundwater EDWC has not changed (29 μg/L for acute and chronic exposure). 

Both the acute and chronic dietary assessments are highly conservative, and assume 100% crop 

treated (%CT), along with tolerance-level residues for all agricultural commodities. Default 

processing factors from DEEM 7.81 were used (for dried beef and cranberry juice) in the 

analyses. The acute (food + water) dietary risk estimate at the 95th percentile of exposure is 1.6% 

of the acute population adjusted dose (aPAD) for females age 13 to 49. This is the only

population subgroup for which an acute endpoint was selected. The chronic (food + water) 

dietary risk estimates are less than or equal to 8.9% of the chronic population adjusted dose 

(cPAD) for all population subgroups. All Infants < 1 year of age is the most highly-exposed 

subgroup, utilizing 8.9% of the cPAD, while the general US population utilizes 3.6% of the 

cPAD. 

Occupational Exposure/Risk

The occupational handler assessment was completed assuming the maximum label application 

rate from the list of end-use products for each crop. The labels allow for application via aerial, 

groundboom, chemigation, backpack, manually-pressurized handwand, mechanicallypressurized handgun, trigger-spray bottle, belly grinder, rotary spreader, and tractor-drawn 

spreader equipment. Based on the activity use pattern, the duration of exposure is expected to be 

short- term (ST; 1 to 30 days) and intermediate-term (IT; 1 to 6 months) for occupational 

scenarios; long-term exposures (greater than 6 months) are not anticipated based on the proposed 

use pattern. No dermal endpoint was selected therefore only inhalation exposure was quantified. 

For the inhalation route of exposure, the same points of departure were chosen for short- and 

intermediate-term exposures; therefore, risk estimates are the same for all durations of exposure. 

An estimated short- and intermediate-term inhalation NOAEL of 70 mg/kg/day for quinclorac 

was selected from a developmental rabbit toxicity study. Therefore, for risk characterization 

purposes, since no inhalation absorption data are available, toxicity by the inhalation route is 

considered to be equivalent to the estimated toxicity by the oral route of exposure. The proposed 

label requires long-sleeved shirt, long pants, shoes plus socks, and chemical-resistant gloves as 

personal protective equipment (PPE) for all applicators and other handlers. All risk estimates of 

the proposed uses for occupational handlers are above the target MOE of 100. Occupational 

handler risk estimates resulted in inhalation MOEs ranging from 4800-940,000 for proposed new 

uses and 1000-1,100,000 for registered uses. The occupational handler inhalation risk estimates 

above 100 do not exceed HED’s level of concern. 
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Based on the Agency's current practices, a quantitative non-cancer occupational post-application 

inhalation exposure assessment was not performed for quinclorac at this time; handler inhalation 

exposure estimates are considered to be protective of occupational post-application inhalation 

exposure scenarios. If new policies or procedures are put into place, the Agency may revisit the 

need for a quantitative occupational post-application inhalation exposure assessment for 

quinclorac.

There is potential for dermal exposure during occupational post-application activities, such as 

crop maintenance activities, scouting, irrigation, and harvesting. However, since no dermal

(short- or intermediate-term) toxicological endpoints were identified, an assessment of postapplication exposure and risk cannot be quantified. 

Residential Exposure/Risk

There are no proposed residential uses at this time; however, there are existing uses for 

quinclorac on residential, non-residential turf (i.e., athletic fields, cemeteries, parks, etc.) and sod 

farms to control several broadleaf and grass weeds that have been reassessed in this document to 

reflect updates to HED’s 2012 Residential SOPs, along with policy changes for body weight 

assumptions. Since individuals can potentially be exposed to treated turf, a residential postapplication assessment was previously conducted (T. Moriarty; 08/13/2008; D342993). The 

revision of residential exposures will impact the human health aggregate risk assessment for 

quinclorac. Post-application exposure and risk estimates resulted in inhalation MOEs ranging 

from 3600-250,000,000. These MOEs were greater than the LOC of 100, and, therefore, were

not of concern.

Aggregate

In general, aggregate exposures are calculated by summing dietary (food and drinking water) and 

residential exposures (residential or other non-occupational exposures). HED reviewed all 

residential sources of exposure to determine which residential exposure scenarios would be 

appropriate to combine with dietary exposure for an aggregate risk assessment. The only

applicable exposure pathways are inhalation (for adult handlers) and incidental oral (for postapplication exposure to children). The short-term aggregate MOEs for the adult handlers and the 

children were 2100 and 1600, respectively, which are above the LOC of 100 and, therefore, not 

of concern. An intermediate-term adverse effect was identified; however, quinclorac is not 

registered for any use patterns that would result in intermediate-term residential exposure.

Therefore, an intermediate-term aggregate risk assessment was not performed nor required.

Additionally, aggregate acute and chronic (food and water) exposures were ≤100% the cPAD for 

all population subgroups as a result of all registered/proposed uses. Thus, acute and chronic 

aggregate exposure to quinclorac is not of concern. 

2.0. HED Recommendations

HED is recommending in favor of registration of quinclorac on the requested crops and 

establishment of tolerances as summarized in Table 2.2.3. HED has evaluated current uses of 

quinclorac and its dimethylamine salt. Tolerance changes are recommended due to recalculation 

of the dietary burden and for harmonization. 
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2.1. Data Deficiencies

Toxicology: None

Residue Chemistry: 

•Data on catfish and crayfish are required, or the label must prohibit use of treated water from 

rice and cranberry fields for aquaculture (See Section 2.3). For registration review, data are 

required or the PM must ensure that all quinclorac labels with uses on rice and cranberry contain 

such a restriction.

•Further expansion of the use of quinclorac to other commodities grown on larger acreages than 

rhubarb and cranberry will trigger a requirement of additional metabolism data.

•For the current petition, Albaugh must supply the Pesticide Repository with analytical standards 

for quinclorac and the quinclorac methyl ester which is used in the current enforcement method.

•For registration review, an analytical standard for the quinclorac DMA salt must be submitted to 

the EPA National Pesticide Standards Repository.

ORE: None.

2.2. Tolerance Considerations

2.2.1. Enforcement Analytical Method

Adequate analytical methods (GC/ECD) are available for enforcing quinclorac tolerances on 

plant (BASF Method A8902; MRID# 41063537) and livestock (BASF Method 268/1; MRID# 

41063536) commodities. Both methods have undergone successful agency method validation 

trials and have been submitted to FDA for publication in PAM II as the tolerance enforcement 

methods. The LOQ of both methods is 0.05 ppm for all matrices. 

In BASF Method 268/1, used for both plant and animal matrices, samples are extracted with 

acetone and dichloromethane and redissolved in acetone/hexane. An aliquot is subjected to GC 

chromatography using a DB-5 column and electron capture detection. Methylated standard is 

used for quantitation. The LOD was reportedly 0.05 ppm, but this was also the lowest level 

validated.

Quinclorac is detected by FDA Multiresidue Protocol B, but not the other FDA Multiresidue 

Method (MRM) Protocols.

2.2.2. Recommended Tolerances

The current tolerance expression for quinclorac is: 

“Tolerances are established for residues of the herbicide quinclorac, including its metabolites and 

degradates, in or on the commodities in the table in this paragraph. Compliance with the 
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tolerance levels specified in this paragraph is to be determined by measuring only quinclorac, 

3,7-dichloro-8-quinolinecarboxylic acid, in or on the commodity.”

The tolerance expression is in accord with our current guidance on tolerance expressions.

Current Petition: Tolerance recommendations for the current petition (IE7957) on low growing 

berries, except strawberries, subgroup 13-07H, and rhubarb are in the first two lines of Table 

2.2.2. 

Tolerance Consideration for Registration Review: Permanent tolerances have been established 

for residues of quinclorac in/on small cereal grain commodities at levels ranging from 0.1 ppm in 

wheat straw to 15 ppm in rice bran [40 CFR §180.463(a)], and for grass forage at 150 ppm and 

grass hay at 130 ppm. There is also a 1200 ppm tolerance for AGF; however, recently reviewed 

data indicate that a tolerance on AGF is not necessary (DP# 344496, G. Otakie, 9/25/08). 

Permanent tolerances have also been established for residues of quinclorac per se in/on livestock 

commodities at levels ranging from 0.05 to 1.5 ppm. 

Based on the recalculated dietary burdens for livestock and the data from the available cattle and 

poultry feeding studies, the current tolerances for livestock commodities are adequate, with the 

exceptions of the tolerances on poultry meat byproducts and hog fat and meat byproducts. Based 

on the recalculated Maximum Dietary Burdens (MDBs) for swine (6.0 ppm) and poultry (5.4 

ppm) and the data from the poultry and cattle feeding studies, the existing tolerances for poultry

meat byproducts and hog fat and meat byproducts are too high as quinclorac residues in these 

commodities are expected to be <0.05 ppm at 1x the MDB. Therefore, the tolerances for these 

livestock commodities should be lowered to 0.05 ppm. Lowering the tolerances on these 

commodities will also harmonize the U.S. tolerances with the existing Canadian MRLs for 

poultry meat byproducts and hog fat and meat byproducts.

In addition, HED notes that the Agency no longer considers rice straw to be a significant 

livestock feedstuff (OPPTS 860.1000, Table I, ChemSAC memo 6/30/08). Therefore, the 

current tolerance for residues of quinclorac on rice straw may be revoked.

The use of the DMA salt of quinclorac will not affect the established tolerances for quinclorac on 

rice, grain sorghum, and wheat.

Table 2.2.2 Tolerance Summary for Quinclorac. § 180.463

Commodity Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity 

Definition

Berry, low growing,

except strawberry, 

subgroup 13-07H

1.1 1.5 Revised level based on OECD tolerance 

calculation procedures. At the time of 

publication of this tolerance, the 

tolerance for residues quinclorac on 

cranberry in § 180.463(b) should be 

revoked.

Rhubarb 0.4 0.5 Revised level based on OECD tolerance 

calculation procedures. 
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Table 2.2.2 Tolerance Summary for Quinclorac. § 180.463

Commodity Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity 

Definition

Currently Established Tolerances Reevaluated for Registration Review

Barley, grain 2.0 2.0 The tolerance needs a footnote to 

indicate that there are no U. S. 

Registrations.

Cattle, fat 0.7 0.7

Cattle, meat byproducts 1.5 1.5

Cattle, meat 0.05 0.05

Egg 0.05 0.05

Goat, fat 0.7 0.7

Goat, meat byproducts 1.5 1.5

Goat, meat 0.05 0.05

Grain, aspirated fractions 1200 revoke Data submitted demonstrate that the 

tolerance is not needed. Current 

tolerance was based on a theoretical

calculation.

Grass, forage 150 150

Grass, hay 130 130

Hog, fat 0.7 0.05 Based on the residue data from the cattle 

feeding and the calculated MDB of 6.0 

ppm for swine, the tolerances can be 

lowered to the method LOQ (0.05 ppm). 

This level is harmonized with Canada. 

Hog, meat byproducts 1.5 0.05 Based on the residue data from the cattle 

feeding and the calculated MDB of 6.0 

ppm for swine, the tolerances can be 

lowered to the method LOQ (0.05 ppm). 

This level is harmonized with Canada. 

Hog, meat 0.05 0.05

Horse, fat 0.7 0.7

Horse, meat byproducts 1.5 1.5

Horse, meat 0.05 0.05

Milk 0.05 0.05

Poultry, fat 0.05 0.05
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Table 2.2.2 Tolerance Summary for Quinclorac. § 180.463

Commodity Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity 

Definition

Poultry, meat byproducts 0.1 0.05 Based on the residue data from the 

poultry feeding and the calculated MDB 

of 5.4 ppm for poultry, the tolerance can 

be lowered to the method LOQ (0.05 

ppm). This level is harmonized with 

Canada.

Poultry, meat 0.05 0.05

Rice, bran 15.0 15.0

Rice, grain 5.0 5.0

Rice, straw 12.0 Revoke Rice straw is no longer a regulated 

livestock feedstuff.

Sheep, fat 0.7 0.7

Sheep, meat byproducts 1.5 1.5

Sheep, meat 0.05 0.05

Sorghum, grain, forage 3.0 3.0

Sorghum, grain, grain 6.0 6.0

Sorghum, grain, stover 1.0 1.0

Wheat, forage 1.0 1.0

Wheat, germ 0.75 0.75

Wheat, grain 0.5 0.5

Wheat, hay 0.5 0.5

Wheat, straw 0.1 0.1

2.2.3. Revisions to Petitioned-For Tolerances and Existing Tolerances

Current Petition: Revisions are recommended to petitioned-for tolerances due to the use of the 

OECD tolerance calculation procedures. The recommended changes are documented in Table 

2.2.2.

Tolerance Revisions for Registration Review: Revisions to current tolerances for registration 

review are documented in Table 2.2.2. Some tolerances are being removed because the 

commodity is no longer regulated. The tolerance for Grain, Aspirated Fractions is being 

removed because it it not necessary. Tolerances on meat, poultry, milk, and eggs are being 

revised based on a recalculation of the dietary burden, and to harmonize internationally.
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2.2.4. International Harmonization

CODEX has not established any established maximum residue limits (MRLs) for quinclorac. 

Canada has established maximum residue limits (MRLs) for quinclorac on selected agricultural 

commodities but not the commodities in the current petition. Recommendations for 

harmonization are in Table 2.2.2 for Registration Review.

2.3.Label Recommendations

2.3.1. Recommendations from Residue Chemistry Reviews

•Cranberry is an aquatic crop, and as such, a label restriction is needed regarding the use 

of treated rice and cranberry fields for aquaculture. Alternatively, the petitioner may

determine residues in catfish and crayfish raised in treated fields and propose tolerances 

for these commodities, if necessary. The label provided for Quinclorac/QuinStar 4-L 

does not contain any restriction against aquaculture.

•For Registration Review, the PM must ensure that all labels for quinclorac on rice and 

cranberry contain a label restriction restricting the use of treated rice and cranberry fields 

for aquaculture.

2.3.2. Recommendations from Occupational Assessment

The proposed label requires long-sleeved shirt, long pants, shoes plus socks, and chemicalresistant gloves as personal protective equipment (PPE) for all applicators and other handlers.

The 12 hour REI which is currently on the label is adequate for the new crop uses with the 

product QUINCLORAC 4L AG Herbicide.

2.3.3. Recommendations from Residential Assessment

None.

3.0. Introduction

3.1. Chemical Identity

Quinclorac is a herbicide for the selective post-emergent control of various annual grasses and 

broadleaf weeds. Quinclorac is adsorbed via the root system and partially through the foliage

and acts as an inhibitor of cell wall synthesis. The nomenclature of quinclorac and quinclorac 

DMA salt are summarized in Table 3.1. 

Table 3.1. Quinclorac and Quinclorac (DMA salt) Nomenclature.

Compound

N

Cl

Cl

O

OH
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Table 3.1. Quinclorac and Quinclorac (DMA salt) Nomenclature.

Common name Quinclorac,

Company experimental name BAS 514 34H 

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

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

CAS registry number 84087-01-4

Molecular weight 242.1

End-use product (EP) Drive® 75 DF 

Compound

N

Cl

Cl

O O

HN

CH3

CH3

H

+

Common name Quinclorac, DMA salt

Company experimental name BAS 514 51H 

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

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

CAS registry number 84087-48-9

Molecular weight 287.2

End-use product (EP) Drive®XLR8 Herbicide, EPA Reg. No. 7969-272; Paramount® L Herbicide, 

EPA Reg. No. 7969-GRA; Facet L Herbicide, EPA Reg. No. 7969-GRL

3.2. Physical/Chemical Characteristics

The physicochemical properties of the technical grade quinclorac are summarized in Table 3.2.1. 

Only several physicochemical properties of the DMA salt of quinclorac are available (Table 

3.2.2). The physical and chemical properties of quinclorac indicate that it is unlikely to volatilize 

and has low potential to accumulate in fatty tissues.

In addition, the registrant has submitted a comparative study of the dissociation behavior of 

quinclorac and its dimethylamine salt (MRID 48051902, “Comparative study of the Dissociation 

Behavior of Quinclorac Acid and its Dimethylamine Salt”). The UV/Vis spectra of quinclorac 

TGAI and the UV/Vis spectra and dissociation constant of quinclorac DMA were presented. 

The results of the study show that in aqueous solutions, the chemical form of the quinclorac 

dimethylamine salt is the same as that of the quinclorac acid form. 
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Table 3.2.1 Physicochemical Properties of the Technical Grade Quinclorac.

Parameter Value Reference

Melting point/range ~269°C D342446, M. Doherty, 

9/11/07

pH 3.4-3.5 RCB 3283 S. Hummel, 

2/26/88

Density ~560 g/L D342446, M. Doherty, 

Water solubility (20°C) 9/11/07 0.0064 g/100 mL

Solvent solubility (g/100 mL at 20°C to 

25°C)

ethanol 0.2 toluene <0.1

Lutrol® <0.1 acetone 0.2

olive oil <0.1 n-octanol <0.1

acetonitrile <0.1 1,2-propandiol <0.1

ethyl acetate 0.1 dichloromethane <0.1

ethyl ether 0.1 n-hexane <0.1

Vapor pressure (20°C) <1.0×10-7 mbar (<0.75×10-7 Torr)

Dissociation constant, pKa 4.34 at 20°C

4.35 at 25°C

Octanol/water partition coefficient, log 

POW (20°C)

1.76 at pH 4

-0.74 at pH 7

3.74 at pH 10

UV/visible absorption spectrum 314 nm, 300 nm, 278 nm (95% ethanol) MRID 48051092

Table 3.2.2 Physicochemical Properties of the Quinclorac, DMA Salt.

Parameter Value Reference

Melting point/range NA

pH NA

Density NA

Water solubility (20°C) NA

Solvent solubility (g/100 mL at 20°C to 

25°C)

NA

Vapor pressure (20°C) NA

Dissociation constant, pKa 4.33 ± 0.15 (Temperature not reported) MRID 48051092

Octanol/water partition coefficient, log 

POW (20°C)

NA

UV/visible absorption spectrum 314 nm, 300 nm, 278 nm (95% ethanol) MRID 48051092

3.3. Pesticide Use Pattern

Proposed new uses. IR-4 is proposing use of the Quinclorac 4-L AG (Reg. No. 42750-169), 

registered to Albaugh, Inc., containing 3.8 lb quinclorac/gallon, in connection with the current 

petition. 
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Table 3.3.1. Summary of Directions for Proposed Use of Quinclorac on Low Growing Berries (Crop Sub- Group 13-

07H), Except Strawberries, and Rhubarb.

Applic. Timing, 

Type, and Equip.

Formulation 

[EPA Reg. 

No. 42750-

169]

Max. Single 

Application 

Rate 

(lb ai/A)

Max. No. 

Applic. per 

Season

Max. Seasonal 

Application 

Rate (lb ai/A)

PHI 

(days)

Use Directions and 

Limitations

Low Growing Berries (Crop Sub- Group 13-07H), Except Strawberries

Foliar; Ground.

QUINCLORA

C 4L AG 

Herbicide 40% 

ai, Dry 

Flowable

(3.8 lb ai/gal)

0.25 lb ai/A 

(8.4 fl oz/A) 2

0.50 lb ai/A 

(16.8 fl oz/A) 60

Re-treatment Interval = 30 

days. 

Ground application (foliar) 

only.

Do not apply by air.

Do not apply to irrigation 

ditches.

Crop oil concentrate permitted.

Rhubarb

Foliar; Ground.

QUINCLORA

C 4L AG 

Herbicide 40% 

ai, Dry 

Flowable

(3.8 lb ai/gal)

0.37 lb ai/A 

(12.6 fl oz/A) 2

0.74 lb ai/A 

(25.2 fl oz/A) 30

Re-treatment Interval = 30 

days. 

Ground application (foliar) 

only.

Do not apply by air.

Do not apply to irrigation 

ditches.

Crop oil concentrate permitted.

Maximum Single Application Rate for Low Growing Berries (Crop Sub- Group 13-07H), Except Strawberries (lb ai/A) = 

(8.4 fl oz/A) (3.8 lb ai/gal)(1 gal/128 fl oz) = 0.25 lb ai/A. Maximum Single Application Rate for Rhubarb (lb ai/A) = 

(12.6 fl.oz/A)(1 gal/1 128 fl.oz) (3.8 lb ai/gal) = 0.37 lb ai/A. 

Existing Uses. Existing uses of quinclorac include use on rice, grain sorghum, wheat, pasture 

and rangeland grasses, and use on barley in Canada for import into the US. The dimethylamine 

salt of quinclorac has recently been registered for use on rice, grain sorghum, and wheat.

Table 3.3.3 provides use sites and maximum application rates for the existing uses for 

quinclorac. Please refer to Section 2.3 for recommended modifications to the proposed label.
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Table 3.3.2. Summary of Quinclorac Registered Uses Assessed Under Registration Review

Commodity Formulation

Product Name 

(EPA Reg. No.)

Application 

Equipment

Max. 

Single 

App Rate

(lb ai/A)

PHI

(days)

Rice

DF

279-3366; 34704-920; 

42750-88; 66222-160; 

7969-222; 7969-313; 

80289-14

Aerial; 

Groundboom

0.503

L 309 42750-169; 71085-26; 

AR080007; AR120003 0.47

WSP 7969-93 0.5

Sorghum and Wheat DF 7969-152; 7969-113; 

66222-160; 42750-131 0.375

L 42750-169; 42750-171 0.35

Agricultural 

fallow/idleland/conservation 

reserves; Nonagricultural 

uncultivated areas/soils; Grass 

forage/fodder/hay; Grasses grown 

for seed; Pastures and Rangelands

DF 7969-113; 42750-131; 

7969-152

Aerial; 

Groundboom

0.75

40

L 42750-169; 42750-171 0.75

Agricultural and nonagricultural 

rights of 

way/fencerows/hedgerows; 

Agricultural uncultivated areas; 

Utility poles/rights of way 

DF

42750-131; 83070-9; 

7969-130; 7969-113; 

66222-160; 42750-131; 

228-592

Backpack; 

Mechanicallypressurized 

Handgun

0.75

(0.15 lb 

ai/gal)*

7-309

L

7969-267; 70506-282; 

42750-220; 42750-172; 

42750-171; 42750-169; 

228-705; 228-595; 228-

531; 228-423; 2217-946; 

2217-919; 2217-901; 

2217-888; 2217-886; 

42750-169; 42750-171 

1.48

(0.296 lb 

ai/gal) *

G 2217-927; 2217-964 Rotary Spreader 0.68

Airports/landing fields DF 228-592; 7969-130

Backpack; 

Manuallypressurized 

0.75

(0.15 lb 

ai/gal)*

NS3
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Table 3.3.2. Summary of Quinclorac Registered Uses Assessed Under Registration Review

Commodity Formulation

Product Name 

(EPA Reg. No.)

Application 

Equipment

Max. 

Single 

App Rate

(lb ai/A)

PHI

(days)

L

228-531; 228-705; 

42750-172; 42750-220; 

70506-282; 7969-267

Handwand; 

Mechanicallypressurized 

Handgun

0.75

(0.15 lb 

ai/gal)*

Commercial/industrial lawns

DF

228-592; 279-3355; 

66222-160; 7969-130; 

83070-9

Backpack; 

Manuallypressurized 

Handwand; 

Mechanicallypressurized 

Handgun

1.4

(0.28 lb 

ai/gal)*

NS

L

7969-267; 70506-282; 

42750-220; 42750-172; 

228-705; 228-595; 228-

531; 228-423; 2217-946; 

2217-919; 2217-901; 

2217-888; 2217-886

0.78

(0.156 lb 

ai/gal)*

G 2217-927; 2217-964 Belly grinder; 

Rotary spreader 0.68

RTU 228-594 Trigger-spray 

bottle

0.76

(0.0172 lb 

ai/bottle)*

Ornamental lawns and turf

DF

83070-9; 7969-130; 

66222-160; 42750-90; 

228-592

Backpack; 

Manuallypressurized 

Handwand; 

Mechanicallypressurized 

Handgun

0.75

(0.15 lb 

ai/gal)*

NS

L

7969-267; 70506-282; 

42750-172; 239-2713; 

228-705; 228-704; 228-

595; 228-423; 2217-946; 

2217-919; 2217-901; 

2217-888; 2217-886

0.78

(0.156 lb 

ai/gal)*

G

2217-927; 2217-964; 

538-296

Hand dispersal; 

Belly grinder; 

Cup; Rotary 

spreader; Spoon

0.68

RTU 228-594; 228-703 Trigger-spray 

bottle

0.76

(0.0172 lb 

ai/bottle)*
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Table 3.3.2. Summary of Quinclorac Registered Uses Assessed Under Registration Review

Commodity Formulation

Product Name 

(EPA Reg. No.)

Application 

Equipment

Max. 

Single 

App Rate

(lb ai/A)

PHI

(days)

Recreation area and residential 

lawns

DF

83070-9; 7969-130; 

66222-160; 279-3355; 

228-592

Backpack; 

Manuallypressurized 

Handwand; 

Mechanicallypressurized 

Handgun

1.4

(0.28 lb 

ai/gal)*

NS

L

7969-267; 72155-86; 

70506-282; 42750-220; 

42750-172; 228-705; 

228-704; 228-595; 228-

531; 228-423; 2217-954; 

2217-946; 2217-945; 

2217-939; 2217-938; 

2217-919; 2217-901; 

2217-896; 2217-894; 

2217-888; 2217-886; 

2217-885; 

0.78

(0.156 lb 

ai/gal)*

G

2217-927; 2217-963; 

2217-964

Belly grinder; 

Rotary spreader 0.68

RTU

2217-887; 2217-917; 

2217-918; 2217-953; 

228-594; 228-703; 239-

2689

Trigger-spray 

bottle

0.76

(0.0172 lb 

ai/bottle)*

Ornamental sod farms (turf)

DF

83070-9; 7969-130; 

66222-160; 42750-90; 

279-3355; 228-592

Aerial; 

Groundboom; 

Chemigation

1.4

90 L

70506-282; 42750-220; 

42750-172; 228-705; 

228-595; 228-531; 228-

423; 2217-946; 2217-

919; 2217-901; 2217-

888; 2217-886

0.78

RTU 228-594 Trigger-spray 

bottle 0.76

Golf course turf DF

42750-90; 228-592; 279-

3355; 83070-9; 7969-

130; 66222-160;

Groundboom; 

Mechanicallypressurized 1.4 NS
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Table 3.3.2. Summary of Quinclorac Registered Uses Assessed Under Registration Review

Commodity Formulation

Product Name 

(EPA Reg. No.)

Application 

Equipment

Max. 

Single 

App Rate

(lb ai/A)

PHI

(days)

L

2217-886; 2217-888; 

2217-901; 2217-919; 

2217-946; 228-423; 228-

531; 228-595; 228-705; 

42750-172; 42750-220; 

70506-282; 7969-267

Handgun

0.78

G 2217-964; 2217-927

Tractor-drawn 

Spreader; Rotary 

spreader

0.68

RTU 228-594 Trigger-spray 

bottle 0.76
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3.4. Anticipated Exposure Pathways

The Registration Division has requested an assessment of human health risk to support the 

proposed new uses of quinclorac. The Pesticide Re-Evaluation Division also has requested an 

assessment for registration review. The variety of end-use products containing quinclorac 

currently registered is as follows; rice, sorghum, and wheat. In addition to agricultural crops, 

quinclorac is also registered for: agricultural fallow/idleland/conservation reserves; 

nonagricultural uncultivated areas/soils; grass forage/fodder/hay; grasses grown for seed; 

pastures and rangelands; agricultural and nonagricultural rights of way/fencerows/hedgerows; 

agricultural uncultivated areas; utility poles/rights of way; airports/landing fields; ornamental sod 

farms; commercial/industrial lawns. Additionally, quinclorac is registered for use by 

commercial applicators and homeowners on lawns, parks, in and around ornamentals, and golf 

courses. The new uses include the following crops; low growing berries, except strawberries, 

subgroup 13-07H, and rhubarb. 

Humans may be exposed to quinclorac in food and drinking water, since quinclorac may be 

applied directly to growing crops and application may result in quinclorac reaching surface and 

ground water sources of drinking water. In the occupational and residential settings, inhalation 

exposure is expected to be of short- and intermediate term durations based on the activity use 

pattern. Long-term exposures (greater than 6 months) are not anticipated based on the proposed 

use pattern. No dermal endpoint was selected, therefore, only inhalation exposure was quantified. 

Incidental oral residential exposures (short-term only) are also expected.

Risk assessments have been previously prepared for the existing uses of quinclorac. This risk 

assessment considers all of the aforementioned exposure pathways based on the proposed new 

uses of quinclorac, but also considers the existing uses as well, particularly for the dietary

exposure assessment. 

3.5. Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf. As a part of every pesticide risk 

assessment, OPP considers a large variety of consumer subgroups according to well-established 

procedures. In line with OPP policy, HED estimates risks to population subgroups from 

pesticide exposures that are based on patterns of that subgroup’s food and water consumption, 

and activities in and around the home that involve pesticide use in a residential setting. 

Extensive data on food consumption patterns are compiled by the USDA under the Continuing 

Survey of Food Intake by Individuals (CSFII) and are used in pesticide risk assessments for all 

registered food uses of a pesticide. These data are analyzed and categorized by subgroups based 

on age, season of the year, ethnic group, and region of the country. Additionally, OPP is able to 

assess dietary exposure to smaller, specialized subgroups and exposure assessments are 

performed when conditions or circumstances warrant. Whenever appropriate, non-dietary

exposures based on home use of pesticide products and associated risks for adult applicators and 

for toddlers, youths, and adults entering or playing on treated areas post-application are 
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 22 of 80

evaluated. Further considerations are currently in development as OPP has committed resources 

and expertise to the development of specialized software and models that consider exposure to 

bystanders and farm workers as well as lifestyle and traditional dietary patterns among specific 

subgroups.

4.0. Hazard Characterization and Dose-Response Assessment

HED reviewed the toxicity database for quinclorac as well as the most recent risk assessment 

which was conducted in association with the new use on pasture/rangeland (D359759, Y. 

Donovan et al, 8/5/2009) and concluded that no changes in the points of departure (PODs) or 

FQPA SF (1x) are warranted. Since the last risk assessment the immunotoxicity study in mice 

was submitted and reviewed (TXR 0052889). The results of this study did not impact the overall 

risk assessment. 

4.1. Toxicology Studies Available for Analysis

The toxicology database for quinclorac is adequate for evaluating and characterizing its toxicity

and selecting endpoints for purposes of risk assessment. Studies considered for this assessment 

include acute lethality (oral, dermal and inhalation routes), primary eye and dermal irritation, 

dermal sensitization, subchronic oral toxicity (rat and mouse), rat 21-day dermal toxicity, dog 

chronic toxicity, rat combined chronic toxicity/carcinogenicity, mouse carcinogenicity, 

developmental toxicity (rat and rabbit), rat two-generation reproductive toxicity, genotoxicity, rat 

metabolism, and mouse immunotoxicity. Since the last risk assessment, the HED HASPOC 

waived the requirement for a neurotoxicity battery (acute and subchronic) and a DNT study

based on a WOE approach that considered (1) lack of neurotoxic effects in the available acute, 

subchronic, chronic, developmental, and reproduction studies; (2) the selected endpoints are 

considered to be protective of neurotoxic effects; (3) dietary exposure to quinclorac is low; and 

(4) residential and occupational MOEs are high (HASPOC TXR 0056385). The requirement of 

a 28-day inhalation toxicity study was also waived previously based on low volatility, low acute 

inhalation toxicity and large extrapolated inhalation MOE (D376603, 23 September 2010). 

4.2. Absorption, Distribution, Metabolism, & Elimination (ADME)

The metabolism of quinclorac ((2,3,4-

14C)3,7-dichloro-8- quinolinecarboxylic acid) following 

oral administration was studied extensively in male and female CD rats. The compound was 

rapidly absorbed and eliminated in the urine following administration of single oral doses of 

(

14C) quinclorac at 15 or 600 mg/kg or after daily exposures of unlabeled compound at 15 mg/kg 

for 14 days followed by a single 15 mg/kg oral dose of labeled compound. Elimination in the 

urine 5 days after dosing accounted for 91 to 98 % of the dose with only 1 to 4 % eliminated in 

the feces. No radioactivity was detected in expired air. Biliary excretion was significant (11.5 to 

14.5 % of the dose) in animals receiving 600 mg/kg. However, most of this radioactivity was 

reabsorbed from the intestines and eliminated in the urine. Most of the radioactivity in the bile is

associated with the glucuronide conjugate of quinclorac. The conjugate is apparently hydrolyzed 

in the intestines and reabsorbed. Almost all the radioactivity in the urine is unchanged 

quinclorac. Radioactive tissue residue levels 5 days after dosing were dose-dependent. Results 

from these and whole-body autoradiography and time-course studies indicate that relatively 
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Page 23 of 80

higher radioactivity levels were detected in the adrenal glands, bone marrow, thyroid, squamous 

epithelium of the non-fundic stomach, and ovaries compared to the other body organs/tissues. In

7-day time-course studies (oral gavage at 15 mg/kg/day or dietary at about 1,000 mg/kg/day) 

maximum 14C residue levels were detected 30 minutes after the final dose; thereafter, residue 

levels decreased with time. Mean 14C residues in plasma were also detected at 30 minutes in 

animals receiving single oral doses of 15, 100, or 600 mg/kg or 15 mg/kg/day for 7 days. 

Elimination was biphasic with half-lives of 3 to 4 hours for the rapid phase at the low doses and 

a half-life of about 13 hours at 600 mg/kg. Peak plasma levels of radioactivity in animals 

receiving higher doses (1200 mg/kg or 600 mg/kg/day for 7 days) were noted for 7 to 48 hours 

post dosing; saturation kinetics were also noted at these higher doses.

4.2.1. Dermal Absorption

Dermal penetration studies on quinclorac are not available. There was no dermal toxicity seen at 

the limit dose of 1000 mg/kg/day in a 21-day dermal toxicity study in rabbits.

4.3.Toxicological Effects

Quinclorac toxicity in experimental animals is observed mostly at doses above 150 mg/kg/day

following subchronic and chronic exposures. Subchronic toxicity includes decreased body

weight gains, increased water intake, increased liver enzymes (SGOT, SGPT) and focal chronic 

interstitial nephritis (rats). Chronic toxic effects include body weight decrement, increase in 

kidney and liver weights, and hydropic degeneration of the kidneys (dogs). At high doses, 

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

adenomas (rats). Neurotoxic effects were not observed in any of the acute, subchronic and 

chronic studies with quinclorac. 

There was no increased qualitative or quantitative fetal or offspring susceptibility in the prenatal 

developmental or postnatal reproduction studies. Developmental toxicity in the rabbit consisted 

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

fetal body weight. These effects occurred at much higher doses than the maternal effects of

decreased food consumption and increased water consumption and decreased body weight gain.

In the rat no developmental toxicity was observed at the highest dose tested (438 mg/kg/day). In 

the 2-generation reproduction study, parental toxicity and offspring toxicity occurred at the same 

dose. Parental toxicity consisted of reduced body weight in both sexes during premating and 

lactation periods. Offspring toxicity consisted of decreased pup weight, developmental delays 

and possible marginal effect on pup viability. No reproductive toxicity occurred at the highest 

dose tested (480 mg/kg/day). 

There are no mutagenicity concerns. Quinclorac is not mutagenic in bacterial assays and does 

not cause unscheduled DNA damage in primary rat hepatocytes. There is also no evidence of a 

genotoxic response in whole animal test systems (in vivo mouse bone marrow micronucleus 

assay). Quinclorac was negative in a mammalian cell in vitro cytogenetic chromosomal

aberration assay in Chinese hamster ovary cells (CHO). 
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Page 24 of 80

Quinclorac was classified in 1992 by the HED Cancer Peer Review committee (CPRC) as a 

group D carcinogen - not classifiable as to human carcinogenicity- based on recommendation by 

the EPA Scientific Advisory Panel (TXR# 0010416). This classification was based on equivocal 

increase in the incidence of one type of benign tumor (pancreatic acinar cell adenomas) in only

one sex and one species of animals (male Wistar rats). Based on this classification, a

quantification of cancer risk is not warranted because the chronic RfD will adequately account 

for all chronic effects, including carcinogenicity, likely to result from exposure to quinclorac.

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

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.

The complete toxicity profile for quinclorac is provided in Appendix A. 

4.4. Safety Factor for Infants and Children (FQPA Safety Factor)

The FQPA Safety Factor Committee recommended in 1998 that the 10x factor for the protection 

of infants and children (as required by FQPA) be removed (TXR 0012902). The removal of the 

10x factor is based on 1) completeness of the data base; 2) there is no indication of increased 

susceptibility of rats or rabbit fetuses to in utero and/or postnatal exposure in the developmental 

and reproductive toxicity data; 3) unrefined (Tier 1) dietary exposure estimates are protective 

since they exaggerate the dietary exposure estimates; and 4) modeling data are used for ground 

and surface source drinking water exposure assessments resulting in conservative upper-bound 

concentrations.

4.4.1. Completeness of the Toxicology Database

The toxicology database for quinclorac is complete and the risk assessment team has concluded 

that the FQPA safety factor can be reduced to 1x. The following acceptable studies are available 

for FQPA consideration: (1) Developmental toxicity studies in rats and rabbits; and (2) Twogeneration reproduction study in rats. Acute and subchronic neurotoxicity studies have been 

waived per HASPOC (TXR# 0056385).

 

4.4.2. Evidence of Neurotoxicity

There are no acute, subchronic or chronic neurotoxicity studies on quinclorac available from the 

registrant or from the published literature. Neurotoxic effects were not observed in any of the 

acute, subchronic and chronic studies with quinclorac. Because of the lack of evidence of 

neurotoxic effects, HIARC (TXR# 0012717) determined in 1998 that no acute, subchronic, or 

developmental neurotoxicity studies are required for quinclorac. This was confirmed by

HASPOC in 2012 (TXR# 0056385). 
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 25 of 80

4.4.3. Evidence of Sensitivity/Susceptibility in the Developing or Young 

Animal

The toxicology database for quinclorac is adequate for the FQPA assessment. Developmental 

toxicity studies in rats and rabbits and the reproduction studies in rats provided no indication of 

increased qualitative or quantitative susceptibility.

4.4.4. Residual Uncertainty in the Exposure Database

There are no residual uncertainties with regard to dietary and residential/occupational exposure. 

The dietary exposure assessments are based on tolerance level residues and 100% crop treated 

information. Modeled values were used for drinking water estimates. Occupational and 

residential exposure assessments are based on reasonable worst-case assumptions and will not 

likely underestimate potential exposure or risk. Based on these data, the quinclorac risk 

assessment team concluded that no additional safety factor is needed to account for exposure 

considerations.

4.5. Toxicity Endpoint and Point of Departure Selections

4.5.1. Dose-Response Assessment

Toxicity endpoints and points of departure (PODs) for dietary and occupational exposure 

scenarios are summarized below. A detailed description of the studies used as a basis for the 

selected endpoints are presented in Appendix A. 

An appropriate endpoint attributable to a single exposure to assess dietary exposure for the 

general populations including infants and children was not available from the oral toxicity

studies including the rat and rabbit developmental toxicity studies.

An acute dietary POD of 200 mg/kg (NOAEL) for the sub-population females 13-49 years old 

was selected from a rabbit developmental toxicity study based on increased rate of resorptions

and post-implantation loss, a decrease in the number of live fetuses, and reduced fetal body

weight seen at 600 mg/kg/day. A UF 100x (10x for intraspecies variation, 10x for interspecies 

extrapolation and a 1x FQPA safety factor) was applied to the dose to obtain an acute reference 

dose/population adjusted dose (aRfD/aPAD) of 2.0 mg/kg.

A chronic dietary POD of 37.5 mg/kg/day (NOAEL) was selected for the general population 

from a carcinogenicity study in mice based on effects on body weight. A UF 100x (10x for 

intraspecies variation, 10x for interspecies extrapolation and a 1x FQPA factor) was applied to 

the dose to obtain a chronic reference dose/population adjusted dose (cRfD/cPAD) of 0.38

mg/kg/day.

A POD of 70 mg/kg/day (NOAEL) for assessing incidental oral short-term (1-30 days) as well as 

short- and intermediate term inhalation exposure scenarios was selected from the developmental 

toxicity study in rabbits based on decreased maternal body weight gain and food consumption 

(and increased water consumption) at 200 mg/kg/day. This is supported by subchronic and 
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chronic dietary data on mice. The LOC for MOE of 100 is applied for this exposure scenario. 

This includes 10X for interspecies extrapolation, 10X for intraspecies variation and a 1x FQPA 

SF.

A dermal endpoint was not selected because an appropriate endpoint was not available (i.e. no 

dermal toxicity was seen at limit dose of 1000 mg/kg/day in a 21-day dermal toxicity study). In 

addition, there were no susceptibility concerns.

Long-term inhalation exposure is not anticipated based on the current use pattern for quinclorac. 

Therefore, long-term PODs have not been established.

4.5.2. Recommendation for Combining Routes of Exposures for Risk 

Assessment

Under FQPA, when there are potential residential exposures to the pesticide, aggregate risk 

assessment must consider exposures from three major sources: oral, dermal and inhalation 

exposures. These combined residential exposures must then be aggregated with dietary exposure 

(food and drinking water) to determine aggregate risk. Dermal exposures were not quantified due 

to a lack of a dermal toxicological endpoint. Because the inhalation and incidental oral endpoints

are based on the same endpoint from the same study, the developmental rabbit, exposures from 

these routes may be combined.

4.5.3. Cancer Classification and Risk Assessment Recommendation

Quinclorac was classified in 1992 by the HED Cancer Peer Review committee (CPRC) as a 

group D carcinogen - not classifiable as to human carcinogenicity- based on recommendation by 

the EPA Scientific Advisory Panel (TXR# 0010416). This classification was based on equivocal 

increase in the incidence of one type of benign tumor (pancreatic acinar cell adenomas) in only

one sex and one species of animals (male Wistar rats). Based on this classification, a

quantification of cancer risk is not warranted because the chronic RfD will adequately account 

for all chronic effects, including carcinogenicity, that may result from exposure to quinclorac.

There was no evidence of carcinogenicity in mice or female rats.

4.5.4. Summary of Points of Departure and Toxicity Endpoints Used in 

Human Risk Assessment

Toxicological doses and endpoints for dietary and non-occupational human health risk 

assessments for quinclorac are presented below in Table 4.5.4.1.
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Table 4.5.4.1. Summary of Toxicological Doses and Endpoints for Quinclorac for Use in Dietary and NonOccupational Human Health Risk Assessments.

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 attributable to a single dose 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

aRfD = 2.0 

mg/kg/day

aPAD = 2.0 

mg/kg/day

Developmental toxicity study in rabbits 

(MRID# 41063525 and 41680501) 

Developmental toxicity LOAEL = 600 

mg/kg/day based on increased early 

resorptions and postimplantation loss, 

decreased live fetuses, decreased fetal 

body 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

cRfD = 0.38

mg/kg/day

cPAD = 

0.38 

mg/kg/day

Carcinogenicity study in mice 

(MRID # 41063523)

LOAEL = 150 mg/kg/day based on 

decreased body weight.

Incidental 

Oral ShortTerm (1-30 

days) 

NOAEL= 70 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Residential 

LOC for 

MOE = 100

Developmental toxicity study in rabbits. 

(MRID# 41063525 and 41680501)

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 was seen at the 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. 

(MRID# 41063525 and 41680501)

Maternal toxicity LOAEL = 200 

mg/kg/day based on decreased maternal 

body weight gain and food consumption,

and increased water consumption.

Inhalation 

Long-Term

(>6 months)

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

Cancer (oral, 

dermal, 

inhalation)

Quinclorac was classified in 1992 by the HED Cancer Peer Review committee (CPRC) as a group 

D carcinogen - not classifiable as to human carcinogenicity- based on recommendation by the EPA 

Scientific Advisory Panel (TXR# 0010416). This classification was based on equivocal increase in 

the incidence of one type of benign tumor (pancreatic acinar cell adenomas) in only one sex and 

one species of animals (male Wistar rats). A quantification of cancer risk is not warranted because 

the chronic RfD will adequately account for all chronic effects, including carcinogenicity, that may 

result from exposure to quinclorac. There was no evidence of carcinogenicity in mice or female 

rats.
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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.
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Table 4.5.4.2 Summary of Toxicological Doses and Endpoints for Quinclorac for Use in Occupational Human 

Health Risk Assessments

Exposure/ 

Scenario

Point of 

Departure

Uncertainty 

Factors

Level of Concern 

for Risk 

Assessment

Study and Toxicological Effects

Dermal (all 

durations)

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

available (no dermal toxicity was seen at the 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. 

(MRID# 41063525 and 41680501)

Maternal toxicity LOAEL = 200 

mg/kg/day based on decreased maternal 

body weight gain and food consumption,

and increased water consumption.

Cancer (oral, 

dermal, 

inhalation)

Quinclorac was classified in 1992 by the HED Cancer Peer Review committee (CPRC) as a group 

D carcinogen - not classifiable as to human carcinogenicity- based on recommendation by the 

EPA Scientific Advisory Panel (TXR# 0010416). This classification was based on equivocal 

increase in the incidence of one type of benign tumor (pancreatic acinar cell adenomas) in only 

one sex and one species of animals (male Wistar rats). A quantification of cancer risk is not 

warranted because the chronic RfD will adequately account for all chronic effects, including 

carcinogenicity, that may result from exposure to quinclorac. There was no evidence of 

carcinogenicity in mice or female rats.

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 

data (i.e., lack of a critical study). MOE = margin of exposure. LOC = level of concern. N/A = not applicable.

4.6. Incident Reports

Quinclorac incidents were previously analyzed in 2007 (M. Hawkins, 08/30/2007, D343370). In 

the previous review, two incidents were identified in IDS from 1999 to 2007; a total of five 

quinclorac cases were identified in the PCC data base 1993 to 2005; and there were no incidents 

identified in National Institute of Occupational Safety and Health Sentinel Event Notification 

System for Occupational Risks (NIOSH SENSOR) data from 1998 to 2003. The document 

concluded that "No mitigation actions are necessary for quinclorac at this time.” Updated 

incident analysis of the Main and Aggregate Incident Data System (IDS) from January 1, 2007,

to August 14, 2012, shows an increase in the number of incidents since the previous incident 

review performed in 2007. This is most likely due to the fact that, prior to 2007, all quinclorac 

products used to treat residential turf could be applied only by a certified applicator. This was a 

self-imposed restriction by the registrant. In 2007, the registrant requested this restriction be 

removed. Since the restriction was removed in 2007, there have been approximately 19 

quinclorac products intended for use on residential turf registered that may be applied by the 

homeowner. Obtaining additional information on current usage data for quinclorac would 

improve future assessments. The updated analysis of NIOSH SENSOR from 1998 to 2008, is 
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not current enough to represent the more recent residential registrations but is consistent with the 

previous 2007 review. It should be noted the SENSOR dataset through 2009 is forthcoming 

(NIOSH plans to provide the updated dataset within the 2012 calendar year) and will be analyzed 

for additional quinclorac cases. 

Overall, only a moderate number of incidents have been reported involving quinclorac. The vast 

majority of these incidents were of low severity, although, there were a few high severity 

outcomes reported in the IDS database. While incident information can be an important source 

of feedback to the Agency, reports of adverse health effects allegedly due to a specific pesticide 

exposure (i.e., an “incident”) are largely self-reported and therefore, generally speaking, neither 

exposure to a pesticide or reported symptom (or the connection between the two) is validated or 

otherwise confirmed. Typically, causation cannot be determined based on incident data. The 

Agency will continue to monitor the incident information and if a concern is triggered, additional 

analysis will be performed (Memo, S. Recore, 9/25/2012, D405512).
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5.0. Dietary Exposure and Risk Assessment 

5.1. Metabolite/Degradate Residue Profile

5.1.1. Summary of Plant and Animal Metabolism Studies

The qualitative nature of quinclorac residues in plants was considered adequately understood for 

the currently registered uses, based upon the metabolism studies on rice, grain sorghum, and 

wheat. In each of these studies, the major 14C-residue in/on various matrices was identified as 

parent compound. Based on the metabolite profiles observed in these studies, quinclorac 

undergoes hydroxylation of the quinoline ring of the parent, followed by conjugation with 

glucose and other biologically available compounds at the hydroxylated site. Some radioactive 

residues are incorporated into the high molecular weight natural products. Based on the above 

studies, HED concluded that parent is the only residue of concern in plant commodities for 

purposes of the tolerance expression and risk assessment. However, all three metabolism studies 

are on grain commodities. A 4th metabolism study, on canola, is available but has not been 

reviewed.

Metabolism in Rice: (MRID 41063534). The metabolism of 14C-ring labeled quinclorac in 

rice plants was studied under growth chamber and field conditions. Growth chamber plants were 

treated at 1.4 lb.ai/A 14C-BAS 514H, an exaggerated dosage rate, at the four leaf stage of plant 

development. Growth-chamber rice plant samples were harvested for analysis at PHI=97 days. 

Field plants were treated at 0.75 lb/A 14C-BAS 514H, at the 3-5 leaf stage. The treatment level 

of field plants simulates the expected herbicide use rate. Field rice plants were harvested at PHI= 

28 and 118 days. Greater than 84% of the TRR in rice grain or straw was identified as the parent 

compound, quinclorac. 

Metabolism in Sorghum: (MRID #44322211). Preemergence and post emergence applications 

of radiolabeled quinclorac were made to a confined sorghum plot. The soil was a loamy sand 

soil with low organic matter. Treatment levels were 0.47 lb ai/A preemergence (0 DAT) and 

0.45 lb a.i./A postemergence (25 DAT) for a total of 0.92 lb ai/A. Crop samples were collected 

and analyzed at various stages of maturity, including forage samples collected at twenty-five 

days after the postemergence treatment, and mature stover and grain collected at the final harvest 

(120 DAT). 

Table 5.1. Distribution and Identification of Residues from Sorghum RACs Treated at 

0.92 lb a.i./A. 

RAC

Radioactive Residues

Identified Unidentified Residuum

quinclorac quinclorac methyl ester Soluble polars Organosoluble

ppm %TRR ppm %TRR ppm %TRR ppm %TTR ppm %TRR ppm

forage 4.01 73.4 2.94 3.6 0.145 18.7 0.750 4.7 0.188 <1 <0.01

fodder 0.87 21.5 0.186 5.9 0.051 52.4 0.455 19.4 0.169 <1 <0.01

grain 0.83 73.5 0.610 1.7 0.014 5.5 0.044 6.6 0.055 <1 <0.01
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The radioactive residues of quinclorac found in sorghum following typical agricultural practices 

consist predominantly of parent compound. A minor metabolite, the methyl ester of quinclorac, 

is found in all tissues, but always at less than 10% TRR. A lower percentage of the residue in 

sorghum fodder was found to be quinclorac, but the majority of the residue was soluble polar 

compounds. The current analytical methodology (BASF Method No. A8902) employs a similar 

acetone extraction step as used in the above extractions. Therefore, the accountability of the 

residues is high. 

Metabolism in Wheat: (MRID #44322207). The test substance used in this study was 

quinclorac (labeled at the 3 position) at two application rates (0.112 lb ai/A (0.45X the proposed 

rate) and 0.446 lb ai/A (1.8X the proposed rate)). Only the higher application rate is presented in 

the table below. Plants were grown in greenhouse conditions and sprayed 22 days after planting, 

when they were in the 3 to 5 leaf stage. Forage samples were collected at a 37-day PHI, straw 

and grain at a PHI of 92 days. 

Table 5.2. Distribution and Identification of Residues from Wheat RACs Treated at 0.446 

lb ai/A Quinclorac. 

RAC

Radioactive Residues

ppm

Identified Unidentified Unextracted Marc

quinclorac quinclorac methyl ester aqueous acetone 

soluble

hydrolyzable non-hydrolyzable

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm

forage 13.1 45.1 5.9 6.4 0.84 38.4 5.1 10.3 0.34 1.9 0.06

straw 8.2 22.4 1.8 12.6 1.0 45.1 3.7 12.4 0.23 3.3 0.06

grain 3.9 68 2.7 3.7 0.15 17.2 0.68 3.3 0.04 0.3 <0.01

The primary path by which plants metabolize quinclorac is through the hydroxylation of the 

quinoline ring of the parent, followed by the conjugation of glucose and other biologically

available compounds at the hydroxylated site. Ultimately, some radioactive residues are 

incorporated into the high molecular weight natural products. 

The petitioner, IR-4, requests a waiver from the requirement of another metabolism study based 

on the following. In the studies to date it has been shown that in plants the primary path by 

which quinclorac is metabolized is through hydroxylation of the quinolone ring of the parent, 

followed by the conjugation of glucose and other biologically available compounds at the 

hydroxylated site. These results were similar for all quinclorac metabolism studies submitted to 

date.

Rhubarb and cranberry are very low acreage crops. Cranberry is commercially grown on just 

over 40,000 acres, and Rhubarb is commercially grown on approximately 2,000 acres in the US 

(based on 2002 census of Agriculture).

In addition, other related quinoline compounds, such as quinoxyfen have shown similar 

metabolism results in that the parent is the primary residue component (D276835, 3/26/2003, G. 

Kramer) when conducted on a wide variety of plant matrices (cucumber, grape, sugarbeet, and 
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tomato). In these studies, quinoxyfen was the primary residue component and other remaining 

compounds were incorporated into natural plant constituents. In cucumber and tomato, 

unchanged quinoxyfen remained largely on the surface of treated plants. The presence of 

multiple unidentified polar residues suggests that metabolism of quinoxyfen does occur to some 

extent to form more polar soluble components with the incorporation into insoluble material. 

Conclusions. While the metabolism of quinclorac is adequately understood with regard to the 

currently registered uses, there are no plant metabolism data for quinclorac on commodities 

similar to cranberry. These data are not being required at this time. However, any further 

expansion of the use of quinclorac to other commodities grown on larger acreages than rhubarb 

and cranberry, will trigger a requirement of additional metabolism data.

The methyl ester of quinclorac was reported in some grain commodities at <15% of the TRR. 

The methyl ester is measured by the enforcement method, which includes a methylation step.

860.1300 Nature of the Residue - Livestock

D241204, J. Stokes, 11/6/1998

D325790, M. Doherty, 9/13/2007

The qualitative nature of quinclorac residues in livestock is understood based upon the adequate 

goat and poultry metabolism studies (MRIDs 41076104 and 41063535, respectively). In both 

studies, quinclorac was the principal residue identified in each commodity. HED concluded that 

parent is the only residue of concern for risk assessment and tolerance expression for livestock. 

However, the enforcement method includes a methylation step and determines the methyl ester 

of quinclorac. 

In a rat metabolism study (MRID 41063533), quinclorac was the primary metabolite reported. 

Elimination was primarily in the urine (91-98%) with small amounts in the feces (1-4%) 

eliminated by day 5 after dosing.

Conclusions. No further livestock metabolism data are required at the present time.

5.1.2. Summary of Environmental Degradation

M. Lowit, N. Andrews, D397720, 8/9/12; M. Lowit, N. Andrews, D405093, 9/14/12

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. Laboratory data 

indicate that quinclorac is stable to hydrolysis, photolysis in sterile water, aerobic soil 

metabolism, and aquatic metabolism (aerobic and anaerobic). 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. Based on available laboratory studies, two major (BH 514-1 

and BH 514 2-OH; >10% applied) and one minor (BH 514-HMe-ester; <10% applied) 

metabolites of quinclorac were identified. The adsorption coefficients for quinclorac and its 

degradation products suggest that leaching could be a route of dissipation. Field studies indicate 

that quinclorac is moderately persistent to persistent (18-176 day half-lives) in terrestrial 
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environments. The octanol/water partition coefficient (KOW) of 0.266 also suggests that 

quinclorac has a low potential to bioaccumulate. A detailed assessment of the environmental 

fate of quinclorac can be found in the new chemical risk assessment (DP 250179+).

5.1.3. Comparison of Metabolic Pathways

Quinclorac was the predominant metabolite in all 3 plant metabolism studies (all in grains), and 

in the livestock metabolism study and the rat metabolism study. Small amounts of a methyl ester 

in plants was reported.

The primary path by which plants metabolize quinclorac is through the hydroxylation of the 

quinoline ring of the parent, followed by the conjugation of glucose and other biologically

available compounds at the hydroxylated site. Ultimately, some radioactive residues are 

incorporated into the high molecular weight natural products. The forage, fodder, and straw 

reported a number of aqueous metabolites, which would be polar metabolites, such as 

hydroxylated metabolites or conjugates.

The qualitative nature of quinclorac residues in livestock is understood based upon adequate goat 

and poultry metabolism studies (MRIDs 41076104 and 41063535, respectively). Quinclorac was 

the principal residue identified in each commodity. 

In a rat metabolism study (MRID 41063533), quinclorac was the primary metabolite reported. 

Elimination was primarily in the urine (91-98%) with small amounts in the feces (1-4%) 

eliminated by day 5 after dosing.

5.1.4. Residues of Concern Summary and Rationale

Quinclorac was not reviewed by ROCKs or its predecessor. Previous risk assessment teams 

determined that quinclorac was the residue of concern since it was the predominant metabolite. 

Table 5.1.4 Summary of Metabolites and Degradates to be included in the Risk 

Assessment and Tolerance Expression

Matrix Residues included in Risk 

Assessment

Residues included in 

Tolerance Expression

Plants

Primary Crop Quinclorac Quinclorac

Rotational Crop Quinclorac Quinclorac

Livestock

Ruminant Quinclorac Quinclorac

Poultry Quinclorac Quinclorac

Drinking Water Quinclorac Not Applicable

5.2. Food Residue Profile
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D397719, D404569, D404912, S. Hummel, G. Otakie, 9/6/12

Residue Analytical Methods: An adequate GC/ECD method is available for enforcing the 

proposed tolerances, and the field trial data were collected using an LC/MS/MS method adequate 

for determining quinclorac, per se. If LC/MS/MS is to be used, a method is needed for the 

methyl ester of quinclorac and any other metabolites found in the required metabolism study.

Multiresidue Methods: Adequate data are available evaluating quinclorac through the FDA 

Multi-Residue Methods Test guidelines, and quinclorac is detected by Protocol B. Quinclorac is 

not detected by the other FDA MRM protocols.

Storage Stability: The available storage stability data are adequate and support the storage 

conditions and durations incurred in the existing field trials, for currently registered uses. The 

IR-4 concurrent storage stability data for rhubarb and cranberry are adequate for residues of 

quinclorac, demonstrating stability for the time and conditions the samples were stored. Storage 

stabilty data are needed for residues of the methyl ester of quinclorac and other residues of 

concern found in the required metabolism study.

Water, Fish, and Irrigated Crops: For existing use on rice and the proposed use on cranberry, a

label restriction is needed regarding the use of treated rice and cranberry fields for aquaculture. 

Alternatively, the petitioner can determine residues in catfish and crayfish raised in treated fields 

and propose tolerances for these commodities if necessary. The label provided for 

Quinclorac/QuinStar 4-L does not contain any restriction against aquaculture.

Conclusions. Data on catfish and crayfish are required, or the label must prohibit use of treated 

water from rice and cranberry fields for aquaculture. For registration review, the PM must ensure 

that all quinclorac labels with uses on rice and cranberry contain such a restriction.

Meat, Milk, Poultry, and Eggs: Adequate cattle and poultry feeding studies are available. The 

uses proposed in this petition do not involve livestock feeds, and will not affect the existing 

tolerances on meat, milk, poultry and eggs. 

For registration review, we are recommending that the tolerance on Grain, aspirated fractions be 

revoked, since data have been received demonstrating that the tolerance is not needed, as 

residues on aspirated grain fractions (AGF) are no higher than the tolerances on the grains. AGF 

were the highest contributor to the livestock dietary burden, but tolerances have since been 

established for grass commodities, which is now the highest contributor to the livestock dietary 

burden.

Conclusions. Tolerances in livestock commodities will be changed in connection with 

Registration Review. Residues are expected to be found in meat byproducts and fat but not in 

milk and eggs. The dietary burden for hogs and poultry is low enough that no quantifiable 

residues are expected in hog and poultry commodities.
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Crop Field Trials:

Cranberry (for Low Growing Berries except strawberry, subgroup 13-07. Five cranberry field 

trials were conducted in the United States during the 2009 growing season, in North American 

Free Trade Agreement (NAFTA) Growing Zones 1 (MA; 2 trials), 5 (WI; 2 trial), and 12 (OR; 1 

trial). The two MA trials (MA01 and MA03) and the two WI trials (WI01 and WI02) were each 

conducted using the same Field Research Director (FRD). Careful examination of the field trial 

records indicates that the only difference between each pair of trials was the use of different 

varieties of cranberry, and distance between MA trials of > 20 miles, and different soil 

characteristics for the MA trials. HED has concluded that there are insufficient distinguishing 

characteristics to classify the WI pair as separate trials; however, the trials were conducted prior 

to development of the guidance on field trial differentiation.

Following two foliar broadcast applications of the 3.8 lb ai/gal SC formulation of quinclorac at 

0.484-0.528 lb ai/A, residues of quinclorac (and per trial averages) in/on cranberry harvested at a 

57- to 62-day PHI were 0.15-0.68 (0.16-0.67) ppm. Applications were made at a 28- to 32-day

retreatment interval (RTI) using ground equipment in spray volumes of 29.7-35.3 gal/A. A crop 

oil concentrate (COC) was added to the spray mixture for each of the applications at 2 pints/A. 

Rhubarb. Four field trials were conducted in the United States during the 2009 growing season 

in the North American Free Trade Agreement (NAFTA) Growing Zones 5 (MI; 1 trial) and 12 

(OR; 3 trials). The two rhubarb trials in Canby, OR (OR11 and OR12) and the trial in Hillsboro, 

OR (OR10) were conducted by the same Field Research Director (FRD). Careful examination of 

the field trial records indicates there are sufficient distinguishing characteristics to classify the 

Hillsboro, OR trial as a separate trial from the Canby, OR trials, based on location (>20 miles 

apart) and spray volume (>25% higher at the Hillsboro site). There are insufficient 

distinguishing characteristics to classify the two Canby, OR trials as separate trials; therefore, the 

Canby, OR trials constitute a single trial with replicate samples for purposes of 860.1500 data 

requirements. The adjustment in trial numbers results in a total of three field trials, with one trial 

in Zone 5 and two trials in Zone 12.

Following two foliar broadcast applications of the 3.8 lb ai/gal SC formulation of quinclorac at 

0.736-0.798 lb ai/A, residues (and per trial averages) of quinclorac in/on rhubarb harvested at a 

29- to 33-day PHI were 0.05-0.231 (0.082-0.205) ppm. The method LOQ was 0.05 ppm. 

Applications were made at a 28- to 31-day retreatment interval (RTI) using ground equipment in 

spray volumes of 19.9-36.7 gal/A. A crop oil concentrate (COC) was added to the spray mixture 

for each of the applications at a rate of 1-2 pints/A. 

Conclusions. Field trial data are adequate to determine residues of quinclorac, per se. Samples 

must be reanalyzed for the methyl ester of quinclorac and any other residue of concern found in 

the metabolism study.

IR-4 should note the current guidance for differentiating field trial sites.

Existing Uses of Remaining Crops: 
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Existing uses of Quinclorac include use on rice, wheat, soybeans, barley (import), grass forage 

and hay. Field trial data are adequate to support the existing uses of quinclorac on rice, grain 

sorghum, barley (imported), and pasture and range grasses. In decline studies, residues generally

degraded substantially within 14 days.

The established tolerance on aspirated grain fractions should be revoked as it is not needed. The 

tolerance on rice straw may be revoked, as rice straw is no longer considered a livestock 

feedstuff.

Processed Food and Feed

There are no processed commodities in connection with the current petition.

For registration review, processing studies submitted to support existing tolerances are adequate. 

Processing studies were submitted for Rice (MRID 41063543), Sorghum (MRID#44322213), 

and Wheat (MRID#44322209). Residues of quinclorac concentrate in hulls and in some grain 

milled products. Available processing data are adequate to support the currently registered uses 

of quinclorac.

Confined and Field Accumulation in Rotational Crops

Adequate rotational crop studies are available to support the use of quinclorac. No residues 

greater than the limit of detection of 0.05 ppm quinclorac were found in mustard leaves and 

turnip leaves and roots when planted 120 and/or 270 days after a quinclorac application to rice. 

(The analytical method was validated down to 0.05 ppm, so 0.05 ppm may be called the limit of 

quantitation (LOQ) or the lower limit of method validation (LLMV). Quantifiable residues of 

concern are not expected at rotational crop intervals of 120 days or longer.

5.3. Water Residue Profile

M. Lowit, N. Andrews, D397720, 8/9/12; M. Lowit, N. Andrews, D405093, 9/14/12

The current assessment is performed according to current EFED guidance and up-to-date models 

including the Tier II surface water model (PRZM/EXAMS) for all uses of quinclorac except 

cranberries and rice. Screening-level Tier I modeling was used to estimate surface water 

concentrations for use on cranberry (provisional cranberry model) and rice (Tier I rice model) 

because the current Tier II model is not parameterized for those uses. The Tier I SCI-GROW 

model was used to estimate groundwater concentrations for all uses.

As in past assessments, this assessment does not consider quinclorac major degradation products 

BH 514-1 and BH 514 2-OH. Although these degradates were detected in the laboratory studies, 

they seem to be intermediate degradates (DP 344485), and were not found in field dissipation 

studies at any significant levels. Furthermore, since quinclorac is persistent and mobile, it is 

expected to be the predominant residue in ground and surface waters.
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Surface water EDWCs (acute = 511 μg/L and chronic = 511 μg/L) resulting from use on rice 

supersede previously recommended EDWCs. The recommended groundwater EDWC has not 

changed (29 μg/L for acute and chronic exposure). 

Table 5.3a. Estimated Drinking Water Concentrations (EDWCs) of Quinclorac in Surface 

Water Sources.

Use Scenario

Estimated Drinking Water Concentrations 

from Surface Water Sources (μg/L)1,2,3

1-in-10 year 

acute

1-in-10 year 

chronic

30-year 

mean

Turf grasses

(1.4 lb ai/A x 1)

(0.76 lb ai/A x 2)

FL turf 441.3 28.5 16.8

PA turf 4,5 58.3 37.8 20.0

FL turf 443.1 32.8 16.3

PA turf 4,5 74.1 62.0 23.7

Sorghum

(0.375 lb ai/A x 2)

(0.245 lb ai/A x 3)

KS sorghum (postplant)626.3 10.5 6.9

KS sorghum 

(postplant/fall)7 20.5 10.2 6.3

KS sorghum (preplant) 23.6 9.5 6.4

Wheat

ND wheat (preplant 

spring) 38.7 26.9 16.5

ND wheat (preplant 

winter) 46.6 28.6 19.3

Rangeland / Pasture

FL turf429.3 21.2 14.6

PA turf4,5 36.6 25.3 16.0

CArangelandhayRLF_v2454.0 36.9 20.5

Rights of way 

/Fencerow 

/Hedgerows

1.5 lb ai/A x 1

0.76 lb ai/A x 2

CArightofwayRLF_v2424.7 14.9 8.2

CArightofwayRLF_v24

27.7 14.3 8.4

Grass grown for 

seed4,5 ORgrassseed4,5 25.4 15.8 11.0

Fallow land

FL turf427.1 19.6 13.7

PA turf4,5 31.5 21.1 13.6

CArangelandhayRLF_v2439.3 27.2 16.4

Grass forage /Fodder 

/Hay

FL turf426.4 18.5 14.4

PA turf4,5 27.1 21.4 14.9

CArangelandhayRLF_v2446.8 31.7 20.6

Low growing berry 

(except cranberry and 

strawberry)

ORberriesOP 3.4 2.0 1.3

Rhubarb CA cole crop RLF_v2 33.8 18.0 11.4

CA lettuce 27.9 18.8 12.9

Cranberry Provisional Cranberry 

Model8 161.9 147.2 --
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Use Scenario

Estimated Drinking Water Concentrations 

from Surface Water Sources (μg/L)1,2,3

1-in-10 year 

acute

1-in-10 year 

chronic

30-year 

mean

Rice Tier I Rice Model9

511.1 511.1 --

Aquatic Weeds10 Labeled concentration 500.0 500.0 --

1 PCA = 1 (www.epa.gov/oppefed1/models/water ) because this is a national drinking water assessment and 

quinclorac is registered for non-agricultural, non-turf uses.

2 BOLD indicates highest EDWC

3 EDWCs based on aerial applications are presented for uses that permit aerial and ground applications at the same 

application rate.

4 Highest value of twelve estimates (first application on the first day of each month) because there are no restrictions 

on when pesticide may be applied.

5 Although permitted, it was assumed that winter applications would be unlikely (December, January, February).

6 Two applications between preemergence and postemergence (up to 12 inches)

7 One application between preemergence and postemergence (up to 12 inches) and one application in the fall prior to 

the first killing frost

8Based on a one-year simulation; 1 in 10 year calculation is not applicable.

9 Based on a single, screening level concentration; 1 in10 year calculation is not applicable.

10 Registered as an experimental use permit.
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Table 5.3b. Estimated Drinking Water Concentrations (EDWCs) of Quinclorac in Ground 

Water Sources 

Use Application Rate

Estimated Drinking Water 

Concentrations from Ground 

Water Sources (μg/L)1

Acute Chronic

Turf grasses 1.4 lb ai/A x 1 27 27

0.76 lb ai/A x 2 29 29

Sorghum 0.375 lb ai/A x 2 and 0.245 lb ai/A x 3 14 14

Wheat 0.245 lb ai/A x 3 14 14

Rangeland / Pasture 0.75 lb ai/A x 1 14 14

Rights of 

way/Fencerow/Hedgerows

1.5 lb ai/A x 1 29 29

0.76 lb ai/A x 2 29 29

Grass grown for seed 0.375 lb ai/A x 2 14 14

Fallow land 0.75 lb ai/A x 1 14 14

Grass forage /Fodder /Hay 0.375 lb ai/A x 2 14 14

Low growing berry 

(except cranberry and 

strawberry)

0.25 lb ai/A x 2 10 10

Rhubarb 0.375 lb ai/A x 2 14 14

Rice2-- -- --

Cranberry2-- -- --

Aquatic Weeds2-- -- --

1 BOLD indicates highest EDWC

2 Groundwater concentrations are not estimated for aquatic uses.

5.4. Dietary Risk Assessment

5.4.1. Description of Residue Data Used in Dietary Assessment

Acute and chronic aggregate dietary (food and drinking water) exposure and risk assessments 

were conducted using the Dietary Exposure Evaluation Model DEEM-FCID, Version 3.16 which 

uses food consumption data from the U.S. Department of Agriculture’s National Health and 

Nutrition Examination Survey, What We Eat in America, (NHANES/WWEIA). This dietary

survey was conducted from 2003 to 2008. These analyses were performed to support the Section 

3 request for quinclorac uses on rhubarb and low growing berry, except strawberry, subgroup 13-

07H and to support Registration Review for quinclorac and the dimethylamine (DMA) salt of 

quinclorac. All registered, pending and proposed uses of quinclorac and the DMA salt of 

quinclorac, as of the date of this memorandum, are included in these assessments. 

Tolerances have been established for quinclorac (40CFR §180.463[a]) in livestock and cereal 

grain commodities. HED has determined that the use of the DMA salt of quinclorac on cereal 

grains will not affect the established tolerances for quinclorac on rice, grain sorghum, and wheat.

The residue of concern (ROC), for both tolerance enforcement and risk assessment, is the parent 

compound, quinclorac. 
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The quinclorac drinking water estimates used in these dietary risk assessments were provided by

EFED (DP# 397720, M. Lowit/N. Andrews, 8/9/12 and DP# 405093, M. Lowit/N.Andrews, 

9/14/12), and incorporated directly into the dietary assessments. Water residues were 

incorporated in DEEM-FCID via entry into the food categories “water, direct, all sources” and 

“water, indirect, all sources.” The estimated drinking water concentrations (EDWCs) from 

existing and proposed uses of quinclorac for both acute and chronic scenarios in ground and 

surface water are 0.029 ppm and 0.511 ppm, respectively. 

Rice (labeled for a single application of 0.5 lb ai/A) was identified as the use resulting in the 

highest EDWCs for surface water. Because the use on rice involves flooding (for which the 

current Tier II model is not parameterized), the surface water EDWCs were assessed using a Tier 

I Rice Model, Version 1.0 (May 8, 2007). Turf grass was identified as the use resulting in the 

highest EDWCs for ground water. The EDWC in ground water was assessed using the Tier I 

Screening Concentration in Ground Water (SCI-GROW, Version 2.3) model. These models, and 

their descriptions, are available at the EPA internet website via the web link, 

http://www.epa.gov/oppefed1/models/water/. No surface or ground water monitoring data were 

available for quinclorac. 

5.4.2. Percent Crop Treated Used in Dietary Assessment

The acute and chronic assessments are based on the assumption that 100% of all commodities 

with tolerances will be treated.

5.4.3. Acute Dietary Risk Assessment

The acute dietary assessment is highly conservative, and assumes 100% crop treated (%CT), 

along with tolerance-level residues for all agricultural commodities. Default processing factors 

from DEEM 7.81 were used (for dried beef and cranberry juice) in the analyses. Tier I modeling 

was used to estimate drinking water concentrations.

The acute (food + water) dietary risk estimate at the 95th percentile of exposure is 1.6% of the 

acute population adjusted dose (aPAD) for females age 13 to 49. This is the only population 

subgroup for which an acute endpoint was selected. 

Generally, the Agency is concerned when risk estimates exceed 100% of the PAD. The acute 

dietary risk estimate for quinclorac is below HED’s level of concern. 

5.4.4. Chronic Dietary Risk Assessment

The chronic dietary assessment is highly conservative, and assumes 100% crop treated (%CT), 

along with tolerance-level residues for all agricultural commodities. Default processing factors 

from DEEM 7.81 were used (for dried beef and cranberry juice) in the analyses. Tier I modeling 

was used to estimate drinking water concentrations.

The chronic (food + water) dietary risk estimates are less than or equal to 8.9% of the chronic 

population adjusted dose (cPAD) for all population subgroups. All Infants < 1 year of age is the 
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most highly-exposed subgroup, utilizing 8.9% of the cPAD, while the general US population 

utilizes 3.6% of the cPAD. 

Generally, the Agency is concerned when risk estimates exceed 100% of the PAD. All chronic 

dietary risk estimates for quinclorac are below HED’s level of concern. 

5.4.5. Cancer Dietary Risk Assessment

Quinclorac was classified in 1992 by the HED Cancer Peer Review committee (CPRC) as a 

group D carcinogen - not classifiable as to human carcinogenicity- based on recommendation by 

the EPA Scientific Advisory Panel (TXR# 0010416). This classification was based on equivocal 

increase in the incidence of one type of benign tumor (pancreatic acinar cell adenomas) in only

one sex and one species of animals (male Wistar rats). Based on this quantification, a

quantification of cancer risk is not warranted because the chronic RfD will adequately account 

for all chronic effects, including carcinogenicity, that may result from exposure to quinclorac. 

5.4.6. Summary Table

Table 5.4.6. Summary of Dietary (Food and Drinking Water) Exposure and Risk for 

Quinclorac

Population Subgroup

Acute Dietary

(95th Percentile) Chronic Dietary Cancer

Dietary 

Exposure 

(mg/kg/day)

% aPAD*

Dietary 

Exposure

(mg/kg/day)

% cPAD*

Dietary 

Exposure

(mg/kg/day)

Risk

General U.S. Population

N/A N/A

0.013728 3.6

N/A N/A

All Infants (< 1 year old) 0.033999 8.9

Children 1-2 years old 0.023500 6.2

Children 3-5 years old 0.019280 5.1

Children 6-12 years old 0.013431 3.5

Youth 13-19 years old 0.010195 2.7

Adults 20-49 years old 0.013614 3.6

Adults 50+ years old 0.012525 3.3

Females 13-49 years old 0.032108 1.6 0.012893 3.4
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6.0. Residential (Non-Occupational) Exposure/Risk Characterization

Ivan Nieves, D404915, D404797, 9/18/12

Although this document addresses proposed new agricultural uses which do not involve 

applications by homeowners or commercial applicators in residential settings, HED has recently 

updated the residential exposure standard operating procedures (SOPs) and body weights to be 

used in all human health assessments as well as the incorporation of new chemical specific 

toxicological information. As a result of the updated policies and parameters, all of the existing 

residential (non-occupational) use patterns have been reassessed in this document because these 

scenarios will impact the quinclorac aggregate assessment.

Although, quinclorac products do not appear to be specifically marketed towards residential 

handler use (i.e., homeowners); a residential handler assessment was performed to be protective 

of any such use. Quinclorac is currently registered for use on turfgrass (lawns, sod, turf areas) 

including but not limited to grounds or lawns around residential and commercial establishments, 

multifamily dwellings, military and other institutions, parks, airports, roadsides, schools, picnic 

grounds, athletic fields, houses of worship, cemeteries, golf courses, prairie grass areas, and sod 

farms. Quinclorac may also be used in and around established landscape ornamentals and 

ornamental gardens. The quinclorac products used in residential settings can be formulated as 

granular, liquid, and dry flowable formulations. 

6.1. Residential Handler Exposure

Based on the anticipated use patterns and current labeling, types of equipment and techniques 

that can potentially be used, residential handler exposure is expected from the existing uses. The 

quantitative exposure/risk assessment developed for residential handlers is based on the 

following scenarios: 

1. Loading/Applying granules for belly grinder,

2. Loading/Applying granules for push type rotary spreader,

3. Loading/Applying granules for a spoon;

4. Loading/Applying granules for a cup and shaker can;

5. Applying granules by hand;

6. Mixing/loading/applying liquid and dry flowable formulations via manually-pressurized 

handwand, a hose-end sprayer, a backpack, and a sprinkler can; 

7. Mixing/loading/applying ready-to-use formulation via a trigger sprayer, and a hose-end 

sprayer.

For residential handlers, HED presents exposure estimates for individuals wearing shorts, shortsleeved shirts, shoes plus socks. Pesticide application area assumed to be performed by adults 

only, however the assessment does group 16 year olds with adults.

Table 6.1 lists the exposures and risk estimates for the residential handler scenarios. The updated 

exposure scenarios result in risk estimates that do not exceed HED’s level of concern (MOEs ≥ 

100).
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Table 6.1. Quinclorac Residential (Non-Occupational) Handler Estimated Risks

Formulation Application 

Equipment/Method

Application 

Rate1 Units

Area 

Treated or 

Amount 

Handled 

Daily

Units 

(per 

day)

Inhalation 

Unit 

Exposure 

(mg/lb ai)2

Inhalation 

Exposure 

(mg/day)

Inhalation 

Absorbed 

Dose3

(mg/kg/day)

Inhalation 

MOE4

Granule

Push-type spreader 0.68 lb 

ai/acre 0.5 acres 0.0026 0.00088 0.000011 6,300,000

Belly grinder

0.0000172 lb ai/ft2

1200 ft20.039 0.0008 0.00001 7,000,000

Spoon

100 ft2

0.087 0.00015 0.0000019 37,000,000

Cup; Shaker can 0.013 0.000022 0.00000028 250,000,000

Hand dispersal 0.38 0.00065 0.0000082 8,600,000

Liquid 

concentrate

Hose-end Sprayer 0.78 lb 

ai/acre 0.5 acres 0.022 0.0086 0.00011 650,000

Manually-pressurized 

handwand 0.16 lb 

ai/gallon 5 gallons 0.018 0.014 0.00018 390,000

Backpack 0.14 0.11 0.0014 50,000

Sprinkler can 0.0000172 lb ai/ft21000 ft20.022 0.00038 0.0000047 15,000,000

Trigger-sprayer

(Ready-to-Use) 0.0172 lb ai/bottle 1 bottle 0.061 0.001 0.000013 5,300,000

Hose-end Sprayer

(Ready-to-Use) 0.76 lb ai/acre 0.5 acres 0.034 0.013 0.00016 430,000

Waterdispersible

Granule / Dry 

Flowable

Manually-pressurized 

handwand 0.28 lb ai/gallon 5 gallons 1.1 1.5 0.019 3,600

Hose-end Sprayer 1.4 lb 

ai/acre 0.5 acres 0.022 0.015 0.00019 360,000

Backpack 0.28 lb 

ai/gallon 5 gallons 1.1 1.5 0.019 3,600

Sprinkler can 0.0000172 lb ai/ft21000 ft20.022 0.00038 0.0000047 15,000,000

1. Max application rate based on various labels containing non-occupational use sites registered for quinclorac

2. Based on Standard Operating Procedures for Residential Pesticide Exposure Assessment http://www.epa.gov/pesticides/science/EPA-OPPHED_Residential%20SOPS_Feb2012.pdf : 

3. Inhalation Dose (mg/kg/day) = daily unit exposure (mg/lb ai) * application rate (lb ai/acre) * amount handled (acres) * inhalation absorption (100%) / body weight (79.5 

kg); 

4. Inhalation MOE = PoD (NOAEL of 70 mg/kg/day) / Daily inhalation dose (mg/kg/day). Level of concern = 100. 
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6.2. Residential Post-Application Exposure

There are no proposed residential uses at this time; however, there are existing registered 

residential uses on lawns and turf for liquid and granular formulations that have been reassessed 

as part of Registration Review. A summary of the exposure and risk is provided below for use in 

performing an aggregate exposure assessment.

6.2.3. Residential (Non-occupational) post-application inhalation

Based on the Agency's current practices, a quantitative residential post-application inhalation 

exposure assessment was not performed for quinclorac at this time primarily because 

quinclorac’s vapor pressure (2.7 x 10-7 mm Hg @ 25.0°C) and Henry's Law Constant (3.72 X 10-

2

Pa m3/mol-1) indicate that the compound is relatively non-volatile under field conditions. The 

Agency sought expert advice and input on issues related to volatilization of pesticides from its 

Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in 

December 2009. The Agency received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

process of evaluating the SAP report and may, as appropriate, develop policies and procedures to 

identify the need for and, subsequently, the way to incorporate post-application inhalation 

exposure into the Agency's risk assessments. If new policies or procedures are put into place, the 

Agency may revisit the need for a quantitative post-application inhalation exposure assessment 

for quinclorac.

6.2.4. Residential (Non-Occupational) Post-Application Dermal and 

Incidental Oral

Post-application short-term dermal and incidental oral exposure is expected from quinclorac 

treated turf in residential settings (i.e., lawns). Dermal exposures were not quantified due to a 

lack of a dermal toxicological endpoint. Incidental oral exposure risk estimates were calculated 

for hand-to-mouth, object-to-mouth, and soil ingestion exposures for 1 to <2 year old children 

playing in the treated turf. Even though there is a granular product, an assessment for episodic 

granular ingestion was not done since there is no applicable endpoint (i.e., no acute dietary point 

of departure for children).
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Table 6.2. Short-Term Oral Non-dietary Ingestion Residential Post-application Exposure and Risk Estimates 

for Quinclorac Resulting from Application to Turf

Lifestage Post-application Exposure 

Scenario

Application 

Rate a

(lb ai/A)

TTRb

(ug/cm2)

Oral Dose c, d, e

(mg/kg/day)

Oral 

MOEsf

Liquids

Child 1 < 2 year old Oral 

Hand-to-Mouth

1.4 0.16

0.021 3,300

Object-to-Mouth 0.00065 110,000

Soil Ingestion 4.7E-05 1,500,000

Granular

Child 1 < 2 year old Oral 

Hand-to-Mouth

0.68 0.015

0.0010 68,000

Object-to-Mouth 0.000063 1,100,000

Soil Ingestion 2.3E-05 3,000,000

a. Application rates = maximum application rates from latest LUIS report current as of 7/19/2012.

b. Turf Transferable Residue (TTR) (Not Chemical Specific) = AR*FAR ((1-FD)

t

)* 4.5x108 [ug/lb]*2.5-8[acre/cm2]

c. Hand-to-Mouth Dose (mg/kg/day) = E = [HR * (FM * SAH) * (ET * N_Replen) * (1- (1- SE)

(Freq_Replen/N-Replens))]

d. Object-to-Mouth Dose (mg/kg/day) = E = [OR* CF1 * SAMO * (ET * N_Replen) * (1- (1- SEO)

(Freq_Replen/N_Replen))]

e. Soil Ingestion Dose (mg/kg/day) = E = SRt * SIgR * CF1

f. Oral MOE = NOAEL (70 mg/kg/day) / Oral Dose (mg/kg/day)

6.3. Combined Residential Risk Estimates (Multiple Exposure Scenarios)

HED combines risk values resulting from separate exposure pathways when it is likely they can 

occur simultaneously based on the use pattern, the behavior associated with the exposed 

population, and the hazard associated with the points of departure. HED reviewed all residential 

sources of exposure to determine which residential exposure scenarios would be appropriate to 

combine with dietary exposure for an aggregate risk assessment. The only applicable exposure 

pathways are inhalation (for adult handlers) and incidental oral (for post-application exposure to 

children). For children, the incidental oral scenarios (i.e., hand-to-mouth, object-to-mouth, and 

soil ingestion) should be considered inter-related and it is likely that they occur interspersed 

amongst each other across time. Combining these scenarios together would be overlyconservative because of the conservative nature of each individual assessment. 

6.4. Residential Risk Estimates for Use in Aggregate Assessment

Table 6.4 reflects the residential risk estimates that are recommended for use in the aggregate 

assessment for quinclorac.

 The recommended residential exposure for use in the adult aggregate assessment reflects 

inhalation exposure from residential handlers mixing/loading/applying water-dispersable 

granule/dry flowable formulations with a manually-pressurized handwand and/or 

backpack equipment.

 The recommended residential exposure for use in the children 1<2 years old aggregate 

assessment reflects hand-to-mouth exposures from post-application exposure to treated 

turf.
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Table 6.4. Residential Risk Estimates for Use in the Quinclorac Aggregate Assessment

Lifestage / Exposure Scenario Dose MOE

Adults – Residential Handler M/L/A, Water-dispersible Granule/Dry Flowable, ManuallyPressurized Handwand and/or Backpack 0.019 3,600

Children 1 < 2 Years Old - Turf (Liquids), Hand-to-Mouth 0.021 3,300

6.5. Residential Bystander Post-application Inhalation Exposure

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for quinclorac at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category III and IV), low vapor pressure 2.7 x 10-7 mm Hg @ 

25.0°C, and the low proposed use rates. However, volatilization of pesticides may be a source of 

post-application inhalation exposure to individuals nearby pesticide applications. The Agency 

sought expert advice and input on issues related to volatilization of pesticides from its Federal 

Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, 

and received the SAP’s final report on March 2, 20101. The Agency is in the process of 

evaluating the SAP report and may, as appropriate, develop policies and procedures to identify

the need for and, subsequently, the way to incorporate post-application inhalation exposure into 

the Agency's risk assessments. If new policies or procedures are developed, the Agency may

revisit the need for a quantitative post-application inhalation exposure assessment for quinclorac.

6.6. Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations. 

This is particularly the case with aerial application (a method proposed to be employed for 

quinclorac), but, to a lesser extent, could also be a potential source of exposure from the ground 

application method also employed for quinclorac. The Agency has been working with the Spray

Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and 

other parties to develop the best spray drift management practices. On a chemical by chemical 

basis, the Agency is now requiring interim mitigation measures for aerial applications that must 

be placed on product labels/labeling. The Agency has completed its evaluation of the new 

database submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, 

and is developing a policy on how to appropriately apply the data and the AgDRIFT computer 

model to its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic 

methods. After the policy is in place, the Agency may impose further refinements in spray drift 

management practices to reduce off-target drift with specific products with significant risks 

associated with drift.

Although a quantitative residential post-application inhalation exposure assessment was not 

performed as a result of pesticide drift from neighboring treated agricultural fields, an inhalation 

exposure assessment was performed for flaggers. This exposure scenario is representative of a 

 

1 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html
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worse case inhalation (drift) exposure and may be considered protective of most outdoor 

agricultural and commercial post-application inhalation exposure scenarios. 

7.0. Aggregate Exposure/Risk Characterization

In accordance with the FQPA, HED must consider and aggregate (add) pesticide exposures and 

risks from three major sources: food, drinking water, and residential exposures. In an aggregate 

assessment, exposures from relevant sources are added together and compared to quantitative 

estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When 

aggregating exposures and risks from various sources, HED considers both the route and 

duration of exposure.

7.1. Acute Aggregate Risk

In examining acute aggregate risk, HED has assumed that the only pathway of exposure relevant 

to the acute time frame is dietary exposure. Therefore, the acute aggregate risk is comprised on 

exposures to quinclorac residues in food and drinking water and is equivalent to the acute dietary

risk estimates summarized in Table 5.4.6 in Section 5.4.3. The acute dietary risk estimates are 

well below HED’s level of concern for Females 13-49 years old.

7.2. Short-Term Aggregate Risk

In examining short-term aggregate risk, HED reviewed all residential sources of exposure to 

determine which residential exposure scenarios would be appropriate to combine with dietary

exposure for an aggregate risk assessment. The only applicable exposure pathways are 

inhalation (for adult handlers) and incidental oral (for post-application exposure to children). For 

children, the incidental oral scenarios (i.e., hand-to-mouth, object-to-mouth, and soil ingestion) 

should be considered inter-related and it is likely that they occur interspersed amongst each other 

across time. Combining these scenarios together would be overly-conservative because of the 

conservative nature of each individual assessment. The recommended residential exposure for 

use in the adult aggregate assessment reflects inhalation exposure from residential handlers 

mixing/loading/applying water-dispersable granule/dry flowable formulations with a manuallypressurized handwand and/or backpack equipment. The recommended residential exposure for 

use in the children 1<2 years old aggregate assessment reflects hand-to-mouth exposures from 

post-application exposure to treated turf.
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 49 of 80

The Aggregate MOEs are above the LOC of 100 and are not of concern (Table 7.2).

Table 7.2 Short-Term Aggregate Risk Calculations

Population

Short-Term Scenario

NOAEL 

mg/kg/day LOC1

Max 

Allowable 

Exposure2

mg/kg/day

Average 

Food and 

Water 

Exposure 

mg/kg/day

Residential 

Exposure 

mg/kg/day3

Total 

Exposure 

mg/kg/day4

Aggregate 

MOE (food, 

water, and 

residential)5

Adults –

Residential 

Handler M/L/A, 

Water-dispersible

Granule/Dry

Flowable, 

ManuallyPressurized 

Handwand and/or 

Backpack1

70 100 0.70 0.013728 0.019 0.032728 2100

Child 1< 2 years 

old – Turf 

(Liquids) Hand-toMouth2

70 100 0.70 0.023500 0.021 0.044500 1600

1 The LOC of 100 includes the standard inter- (10x) and intra- (10x) species uncertainty factors totaling 100, as well 

as an FQPA SF of 1x.)

2 Maximum Allowable Exposure (mg/kg/day) = NOAEL/LOC

3 Residential Exposure = [Oral exposure + Inhalation Exposure]. (Source: Table 6.4, Section 6.4).

4 Total Exposure = Avg Food & Water Exposure + Residential Exposure)

5 Aggregate MOE = [NOAEL / (Avg Food & Water Exposure + Residential Exposure)] 

7.3. Intermediate-Term Aggregate Risk

Intermediate-term aggregate exposure takes into account intermediate-term residential exposure 

plus chronic exposure to food and water (considered to be a background exposure level). An 

intermediate-term adverse effect was identified, however, quinclorac is not registered for any use 

patterns that would result in intermediate-term residential exposure; therefore, an intermediateterm aggregate risk assessment was not performed nor required. 

7.4. Chronic Aggregate Risk

In examining chronic aggregate risk, HED has assumed that the only pathway of exposure 

relevant to the chronic time frame is dietary exposure. Therefore, the chronic aggregate risk is 

comprised of exposures to quinclorac residues in food and drinking water and is equivalent to the 

chronic dietary risk estimates summarized in Table 5.4.6 in Section 5.4.4. The chronic risk 

estimates are below HED’s level of concern for all population subgroups. 
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 50 of 80

7.5. Cancer Aggregate Risk

HED has concluded that assessments using a non-linear approach (e.g. a chronic RfD-based 

approach) will adequately account for all chronic toxicity, including carcinogenicity that could 

result from exposure to quinclorac. Chronic aggregate risk estimates are below HED’s level of 

concern, therefore, cancer risk is also below HED’s level of concern. 

7.6. Cumulative Exposure/Risk Characterization

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a 

common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as 

to quinclorac and any other substances and quinclorac does not appear to produce a toxic 

metabolite produced by other substances. For the purposes of this tolerance action, therefore, 

EPA has not assumed that quinclorac has a common mechanism of toxicity with other 

substances. For information regarding EPA’s efforts to determine which chemicals have a 

common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the 

policy statements released by EPA’s Office of Pesticide Programs concerning common 

mechanism determinations and procedures for cumulating effects from substances found to have 

a common mechanism on EPA’s website at http://www.epa.gov/pesticides/cumulative/.

8.0. Occupational Exposure/Risk Characterization

There are registered agricultural uses associated with quinclorac, and the proposed new uses (i.e., 

rhubarb and low growing berries in subgroup 13-07H, except strawberry) are agricultural uses as well; 

therefore, there is the potential for occupational handler and post-application exposure. However, 

since no dermal endpoints were selected, only inhalation exposure estimated risks were able to 

be quantified.

8.1. Short-/Intermediate-/Long-Term/Cancer (if needed) Handler Risk

Table 8.1.1 presents the short-term inhalation risk estimates for the quinclorac proposed new 

uses. Table 8.1.2 presents occupational handler risk estimates associated with already registered 

uses. Since the short- and intermediate-term endpoints and PODs are the same for each route of 

exposure, only short-term exposures were estimated, and are considered protective of 

intermediate-term exposure and risk. Occupational handler scenarios resulted in estimated 

MOEs greater than the levels of concern (inhalation LOC = 100) at baseline. 

The Agency has evaluated scenarios that may be limited in nature such as flagging during aerial 

applications because engineering controls (i.e., Global Positioning Satellite technology) are now 

predominantly used as indicated by the 1998 National Agricultural Aviation Association 

(NAAA) survey of their membership. It appears, however, flaggers are still used in 

approximately 10 to 15 percent of aerial application operations. In cases like these, the Agency

strongly encourages the use of the engineering control system but will continue to evaluate risks 

for flaggers and any other population where a clear exposure pathway exists until the potential 

for exposure is eliminated. The Agency is aware that NAAA is conducting another survey on 

exposure issues and will consider those results as are timely and appropriate.
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 51 of 80

HED has no data to assess exposure for pilots using open cockpits. The only data available are

representing exposure for pilots in enclosed cockpits. Therefore, pilot exposure and risk 

estimates are determined assuming use of engineering control (enclosed cockpits) and baseline 

attire (i.e., long-sleeve shirt, long pants, shoes, and socks); pilots are not required to wear 

protective gloves. With this level of protection, there are no risk estimates of concern for aerial 

applicators.
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 52 of 80

Table 8.1.1. Quinclorac Occupational Handler Risk Estimates For Proposed New Uses

Site

Exposure Scenario Application Rate1 Amount Handled 

/ Area Treated2

Inhalation 

Unit 

Exposures3

(ug/lb ai)

Inhalation Dose4

(mg/kg-day)

Inhalation 

MOE5

Worker 

Activity Formulation Application Equipment

Valu

e

Units Value Units No-R

Low growing 

berries, except 

strawberries, 

subgroup 13-07H

M/L DF/WDG Aerial; Chemigation 0.25 lb ai/acre 350acres 8.96 0.0098 7,100

Groundboom 80 0.0022 31,000

Applicato

r

Spray

(all starting 

formulations)

Aerial

0.25 lb ai/acre

350

acres

0.068

(Engineering 

Controls)

0.000074

(Engineering 

Controls)

940,000

(Engineering 

Controls)

Groundboom 80 0.34 0.000085 820,000

M/L/A DF/WDG

Mechanicallypressurized 

Handgun

0.025 lb 

ai/gallon 1000 gallons 3.9 0.0012 57,000

Flagger

Spray

(all starting 

formulations)

Aerial 0.25 lb ai/acre 350 acres 0.35 0.00038 180,000

Rhubarb

M/L DF/WDG Aerial; Chemigation 0.37 lb ai/acre 350

acres 8.96 0.015 4,800

M/L Groundboom 80 0.0033 21,000

Applicato

r

Spray

(all starting 

formulations)

Aerial

0.37 lb ai/acre

350 acres

0.068

(Engineering 

Controls)

0.00011

(Engineering 

Controls)

640,000

(Engineering 

Controls)

Groundboom 80 acres 0.34 0.00013 560,000

M/L/A DF/WDG

Mechanicallypressurized 

Handgun

0.037 lb 

ai/gallon 1000 gallons 3.9 0.0018 39,000

Flagger

Spray

(all starting 

formulations)

Aerial 0.37 lb ai/acre 350 acres 0.35 0.00057 120,000

1 Based on the proposed crops listed on the registered label (EPA Reg. No. 42750-169);

2 Exposure Science Advisory Council Policy #9.1 ;

3 Based on “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March, 2012); 

4

Inhalation Dose = Dermal Unit Exposure (ug/lb ai) x Conversion Factor (0.001 mg/ug) x Application Rate (lb ai/A) x Area Treated or Amount Handled (A/day or gal/day)/BW (kg);

5

Inhalation MOE = Inhalation NOAEL (70 mg/kg/day)/ Inhalation Dose (mg/kg/day); LOC = 100.
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 53 of 80

Table 8.1.2. Summary of Quinclorac Registered Uses

Site

Exposure Scenario Application Rate1 Amount Handled 

/ Area Treated2

Inhalation 

Unit 

Exposures3

(ug/lb ai)

Inhalation 

Dose4

(mg/kg-day)

Inhalation 

MOE5

Worker 

Activity Formulation Application Equipment Value Units Value Units No-R 

Rice

M/L

DF/WDG

Aerial

0.5

lb 

ai/acre

1200

acres

8.96

0.068 1,000

Groundboom 200 0.011 6,200

WSP

Aerial 1200

0.068

(Engineering 

Controls)

0.00051

(Engineering 

Controls)

140,000

(Engineering 

Controls)

Groundboom 200

0.24

(Engineering 

Controls)

0.00030

(Engineering 

Controls)

230,000

(Engineering 

Controls)

L/SC/EC

Aerial

0.47

1200

0.219

0.0016 45,000

Groundboom 200 0.00026 270,000

Applicator

Spray

(all starting 

formulations)

Aerial

0.5

lb 

ai/acre

1200

acres

0.068

(Engineering 

Controls)

0.00051

(Engineering 

Controls)

140,000

(Engineering 

Controls)

Groundboom 200 0.34 0.00043 160,000

Aerial

0.47

1200

0.068

(Engineering 

Controls)

0.00048

(Engineering 

Controls)

150,000

(Engineering 

Controls)

Groundboom 200 0.34 0.0004 180,000

Flagger

Spray

(all starting 

formulations)

Aerial

0.5

lb 

ai/acre 350 acres 0.35

0.00077 91,000

0.47 0.00072 97,000

Sorghum and Wheat

M/L

DF/WDG

Aerial

0.375

lb 

ai/acre

1200

acres

8.96 0.050 1,400

Groundboom 200 8.96 0.0084 8,300

L/SC/EC

Aerial

0.35

1200 0.219 0.0012 61,000

Groundboom 200 0.219 0.00019 370,000

Applicator

Spray

(all starting 

formulations)

Aerial 0.375 lb 

ai/acre 1200 acres

0.068

(Engineering 

Controls)

0.00038

(Engineering 

Controls)

180,000

(Engineering 

Controls)
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 54 of 80

Table 8.1.2. Summary of Quinclorac Registered Uses

Site

Exposure Scenario Application Rate1 Amount Handled 

/ Area Treated2

Inhalation 

Unit 

Exposures3

(ug/lb ai)

Inhalation 

Dose4

(mg/kg-day)

Inhalation 

MOE5

Worker 

Activity Formulation Application Equipment Value Units Value Units No-R 

Groundboom 200 0.34 0.00032 220,000

Aerial

0.35

1200

0.068

(Engineering 

Controls)

0.00036

(Engineering 

Controls)

200,000

(Engineering 

Controls)

Groundboom 200 0.34 0.00030 230,000

Flagger

Spray

(all starting 

formulations)

Aerial 0.375

lb 

ai/acre 350 acres 0.35

0.00057 120,000

Aerial 0.35 0.00054 130,000

Agricultural fallow/idleland/conservation 

reserves; Nonagricultural uncultivated 

areas/soils; Grass forage/fodder/hay; Grasses 

grown for seed; Pastures and Rangelands

M/L

DF/WDG

Aerial

0.75 lb 

ai/acre

1200

acres 8.96

0.10 690

Chemigation 350 0.029 2,400

Groundboom 200 0.017 4,200

L/SC/EC

Aerial

0.73 lb 

ai/acre

1200

acres 0.219

0.0024 29,000

Chemigation 350 0.00070 100,000

Groundboom 200 0.00040 180,000

Applicator

Spray

(all starting 

formulations)

Aerial

0.75 lb 

ai/acre

1200

acres

0.068

(Engineering 

Controls)

0.00077

(Engineering 

Controls)

92,000

(Engineering 

Controls)

Groundboom 200 0.34 0.00064 110,000

Flagger

Spray

(all starting 

formulations)

Aerial 0.75 lb 

ai/acre 350 acres 0.35 0.0012 61,000

Agricultural and nonagricultural rights of 

way/fencerows/hedgerows; Agricultural 

uncultivated areas; Utility poles/rights of way

M/L DF/WDG

Mechanicallypressurized 

Handgun

0.15 lb 

ai/gallon 1000 gallons 8.96 0.017 4,200

Applicator

Spray

(all starting 

formulations)

Mechanicallypressurized 

Handgun

0.15

lb 

ai/gallon 1000 gallons 3.9

0.0073 9,600

0.296 0.014 4,900

L/A G Rotary spreader 0.68 lb 

ai/acre 5 acres 10 0.00043 160,000

M/L/A DF/WDG Backpack 0.15 lb 40 gallons 2.58 0.00019 360,000
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 55 of 80

Table 8.1.2. Summary of Quinclorac Registered Uses

Site

Exposure Scenario Application Rate1 Amount Handled 

/ Area Treated2

Inhalation 

Unit 

Exposures3

(ug/lb ai)

Inhalation 

Dose4

(mg/kg-day)

Inhalation 

MOE5

Worker 

Activity Formulation Application Equipment Value Units Value Units No-R 

L/SC/EC 0.296 ai/gallon 0.00038 180,000

Airports/landing fields M/L/A DF/WDG; 

L/SC/EC

Backpack

0.15 lb 

ai/gallon 40 gallons

2.58 0.00019 360,000

Manuallypressurized 

Handwand

30 0.0023 31,000

Mechanicallypressurized 

Handgun

0.75 lb 

ai/acre 5 acres 42 0.0020 35,000

Commercial/industrial lawns; Recreation area 

and residential lawns; Ornamental lawns and 

turf

L/A G

Belly grinder

0.68 lb 

ai/acre

1

acres

62 0.00053 130,000

Rotary spreader 5 10 0.00043 160,000

Applicator RTU (L) Trigger-spray 

bottle 0.0172 lb ai/bottle 5 bottles 61.2 0.000066 1,100,000

M/L/A

DF/WDG

Backpack

0.28 lb 

ai/gallon 40 gallons

2.58 0.00036 190,000

Manuallypressurized 

Handwand

30 0.0042 17,000

Backpack

0.15 lb 

ai/gallon 40 gallons

2.58 0.00019 360,000

Manuallypressurized 

Handwand

30 0.0023 31,000

Mechanicallypressurized 

Handgun

1.4

lb 

ai/acre 5 acres 42

0.0037 19,000

Mechanicallypressurized 

Handgun

0.75 0.0020 35,000

L/SC/EC

Backpack

0.16 lb 

ai/gallon 40 gallons

2.58 0.00021 340,000

Manuallypressurized 

Handwand

30 0.0024 29,000

Mechanicallypressurized 

Handgun

0.78 lb 

ai/acre 5 acres 1.9 0.000093 760,000

Ornamental lawns and turf M/L DF/WDG Aerial; 1.4 lb 350 acres 8.96 0.055 1,300
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 56 of 80

Table 8.1.2. Summary of Quinclorac Registered Uses

Site

Exposure Scenario Application Rate1 Amount Handled 

/ Area Treated2

Inhalation 

Unit 

Exposures3

(ug/lb ai)

Inhalation 

Dose4

(mg/kg-day)

Inhalation 

MOE5

Worker 

Activity Formulation Application Equipment Value Units Value Units No-R 

Chemigation ai/acre

Groundboom 80 0.013 5,600

L/SC/EC

Aerial; 

Chemigation 0.78

350

0.219

0.00075 94,000

Groundboom 80 0.00017 410,000

Applicator

Spray

(all starting 

formulations)

Aerial

1.4 lb 

ai/acre

350

acres

0.068

(Engineering 

Controls)

0.00042

(Engineering 

Controls)

170,000

(Engineering 

Controls)

Groundboom 80 0.34 0.00048 150,000

RTU (L) Trigger-spray 

bottle 0.0172 lb ai/bottle 5 bottles 61.2 0.000066 1,100,000

Flagger

Spray

(all starting 

formulations)

Aerial 1.4 lb 

ai/acre 350 acres 0.35 0.0022 33,000

Golf course turf

M/L

DF/WDG Groundboom 1.4

lb 

ai/acre 40 acres

8.96 0.0063 11,000

G

Tractor-drawn 

Spreader 0.68 1.7 0.00058 120,000

L/SC/EC Groundboom 0.78 0.219 0.000085 820,000

L/A G Rotary spreader 0.68 lb 

ai/acre 5 acres 10 0.00043 160,000

Applicator

G

Tractor-drawn 

Spreader 0.68

lb 

ai/acre 40 acres

1.2 0.00041 170,000

Spray

(all starting 

formulations)

Groundboom 0.78 0.34 0.00013 530,000

M/L/A

DF/WDG Mechanicallypressurized 

Handgun

1.4

lb 

ai/acre 5 acres

42 0.0037 19,000

L/SC/EC 0.78 1.9 0.000093 760,000

1 Based on latest LUIS report current as of 7/19/2012;

2 Exposure Science Advisory Council Policy #9.1;

3 Based on “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March, 2012); 

4

Inhalation Dose = Dermal Unit Exposure (ug/lb ai) x Conversion Factor (0.001 mg/ug) x Application Rate (lb ai/A) x Area Treated or Amount Handled (A/day or gal/day)/BW (kg);

5

Inhalation MOE = Inhalation NOAEL (70 mg/kg/day)/ Inhalation Dose (mg/kg/day); LOC = 100.
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 57 of 80

8.2. Short-/Intermediate-/Long-Term/Cancer (if needed) Post-Application Risk

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure.

8.2.1. Dermal Post-application Risk

Quinclorac proposed new uses, as well as already registered, include agricultural sites including 

rice, sorghum, wheat, rhubarb and low growing berries (subgroup 13-07H), except strawberries. 

Since no toxicological dermal endpoint was selected; no dermal occupational risk estimate was 

quantified, and therefore no risks of concerns were identified.

It is the policy of HED to use the best available data to assess post-application exposure. 

Sources of generic post-application data, used as surrogate data in the absence of chemicalspecific data, are derived from Agricultural Reentry Task Force (ARTF) exposure monitoring 

studies, and, as proprietary data, are subject to the data protection provisions of FIFRA. The 

standard values recommended for use in predicting post-application exposure that are used in 

this assessment, known as “transfer coefficients”, are presented in the “Science Advisory

Council for Exposure (ExpoSAC) Policy 3” 

http://www.epa.gov/pesticides/science/exposac_policy3.pdf)), which, along with additional 

information about the ARTF data, can be found at http://www.epa.gov/pesticides/science/postapp-exposure-data.html.

8.2.2. Inhalation Post-application Risk

Based on the Agency's current practices, a quantitative post-application inhalation exposure

assessment was not performed for quinclorac at this time primarily because of its vapor pressure 

(2.7 x 10-7 mm Hg @ 25.0°C), and the proposed use rates. However, there are multiple potential 

sources of post-application inhalation exposure to individuals performing post-application 

activities in previously treated areas. These potential sources include volatilization of pesticides 

and re-suspension of dusts and/or particulates that contain pesticides. The Agency sought expert 

advice and input on issues related to volatilization of pesticides from its Federal Insecticide, 

Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and 

received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

process of evaluating the SAP report as well as available post-application inhalation exposure 

data generated by the Agricultural Reentry Task Force and may, as appropriate, develop policies 

and procedures, to identify the need for and, subsequently, the way to incorporate occupational 

post-application inhalation exposure into the Agency's risk assessments. If new policies or 
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 58 of 80

procedures are put into place, the Agency may revisit the need for a quantitative occupational 

post-application inhalation exposure assessment for quinclorac.

Although a quantitative post-application inhalation exposure assessment was not performed, an 

inhalation exposure assessment was performed for occupational handlers. Handler exposure 

resulting from application of pesticides outdoors is likely to result in higher exposure than postapplication exposure. Therefore, it is expected that these handler inhalation exposure estimates 

would be protective of most occupational post-application inhalation exposure scenarios.

9.0. References

Cropp-Kholligian, B. 9/24/2012. Quinclorac and the Dimethylamine (DMA) Salt of Quinclorac. 

Acute and Chronic Aggregate Dietary (Food and Drinking Water) Exposure and Risk 

Assessments for the Section 3 Registration Action on Rhubarb and Low Growing Berry except 

Strawberry, Subgroup 13-07H and the Registration Review Action. D404795 and D404914

Y. Donovan et al, 8/5/2009. PP# 8F7442. Human Health Risk Assessment for Quinclorac New 

Use on Pasture/Rangeland. D359759.

Drew, W. and Dow, M. 6/2/2009. Quinclorac. Human Health Risk Assessment for the Proposed 

Food/Feed Use of the Herbicide (Associated with Section 18 Registration) on Cranberries in 

Massachusetts.

Greear, W. and Rinde, E. 8/26/1992. Second Carcinogenicity Peer Review of Quinclorac. TXR 

No. 0010416.

Hummel, S. and Otakie, G. 9/6/2012. Draft. Quinclorac on Rhubarb and Low Growing Berries 

(except Strawberry). Summary of Analytical Chemistry and Residue Data. Residue Chemistry

Considerations for Registration Review. D397719, 404569, 404912

Lowit, M. and Andrews, M. 8/9/2012. Quinclorac: Drinking Water Assessment to Support 

Proposed New Use on Rhubarb and Low Growing Berries Except Strawberry (subgroup 13-

07H). D397720. 

Lowit, M. and Andrews, M. 9/14/2012. Quinclorac: Registration Review Drinking Water 

Assessment. D405093. 

Nieves, I. 9/18/2012. Quinclorac: Occupational and Residential Exposure/Risk Assessment for 

Registration Review and for Proposed Uses on Rhubarb and Cranberry (and other Low Growing 

Berries in Subgroup 13-07H, except strawberry). D404915, D404797

O’Rourke, K. 9/23/2010. Quinclorac. Response to BASF Corporation’s Request to Waive the 

Requirement of a 28-Day Inhalation Toxicity Study for Quinclorac. D376603. TXR No. 

0055511. 

Recore, S. 9/25/12. Quinclorac: Updated Tier 1 Review of Human Incidents. D405512. 
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 59 of 80

Shah, PV and Rowland, J. 8/4/1998. Quinclorac – Report of the Hazard Identification 

Assessment Review Committee. HED Doc. No. 012717.

Tarplee, B. 10/14/1998. Quinclorac – Report of the FQPA Safety Factor Committee. TXR No. 

0012902.

Van Alstine, J. 9/2012. Quinclorac: Summary of Hazard and Science Policy Council (HASPOC) 

Meeting of June 21, 2012: Recommendations on the need for a neurotoxicity Battery Study and 

a DNT study. TXR #: 0056385
Quinclorac Human Health Risk Assessment DP Nos. 404794, 404808

Page 60 of 80

Appendix A. Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements

The requirements (40 CFR 158.340) for [Type of Use (e.g., food vs. non food)] for [CHEMICAL NAME] are in 

Table 1. Use of the new guideline numbers does not imply that the new (1998) guideline protocols were used.

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity.......................................................

870.1200 Acute Dermal Toxicity ..................................................

870.1300 Acute Inhalation Toxicity..............................................

870.2400 Primary Eye Irritation....................................................

870.2500 Primary Dermal Irritation ..............................................

870.2600 Dermal Sensitization......................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)...............................................

870.3150 Oral Subchronic (nonrodent).........................................

870.3200 21-Day Dermal ..............................................................

870.3250 90-Day Dermal ..............................................................

870.3465 21-/90-Day Inhalation....................................................

yes

yes

yes

no

no2

yes

yes1

yes

-

-

870.3700a Developmental Toxicity (rodent)...................................

870.3700b Developmental Toxicity (nonrodent).............................

870.3800 Reproduction .................................................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent)..............................................

870.4100b Chronic Toxicity (nonrodent)........................................

870.4200a Oncogenicity (rat)..........................................................

870.4200b Oncogenicity (mouse)....................................................

870.4300 Chronic/Oncogenicity....................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.5100 Mutagenicity—Gene Mutation - bacterial.....................

870.5300 Mutagenicity—Gene Mutation - mammalian................

870.5375 Mutagenicity—Structural Chromosomal Aberrations...

870.5900 Mutagenicity—Other Genotoxic Effects.......................

yes

yes

yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen).....................................

870.6100b 90-Day Neurotoxicity (hen)...........................................

870.6200a Acute Neurotox. Screening Battery (rat) .......................

870.6200b 90-Day Neuro. Screening Battery (rat)..........................

870.6300 Develop. Neuro..............................................................

no

no

no3

no3

no3

-

-

-

-

-

870.7485 General Metabolism ......................................................

870.7600 Dermal Penetration........................................................

870.7800 Immunotoxicity .............................................................

yes

-

yes

yes

-

yes

1 The data requirement for a dog 90-day subchronic oral toxicity is satisfied by the dog 1-year chronic oral study.

2 waived (D376603, TXR 0055511)

3 waived (HASPOC, TXR 0056385)
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A.2 Toxicity Profiles

Table A.2.1 Acute Toxicity Profile – Quinclorac

Guideline 

No.

Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral - rat 41063505

(1989)

LD50 >2610 mg/kg III 

870.1100 Acute oral - rat 41063506

(1983)

LD50 (male) = 3060 mg/kg

LD50 (female) = 2190 mg/kg

LD50 (combined) = 2680 

mg/kg

III

870.1100 Acute oral - mouse 41063507

(1986)

LD50 >5000 mg/kg IV

870.1200 Acute dermal - rat 41063509

(1983)

LD50 > 2000 mg/kg III

870.1300 Acute inhalation - rat 41063510

(1985)

LC50 > 5.2 mg/L

(4 hr exposure)

III

870.2400 Acute eye irritation –

rabbit

41063511

(1983)

Mild irritant reversible by 

day 8

III

870.2500 Acute dermal irritation –

rabbit

41063512

(1983)

Not an irritant III

870.2600 Skin sensitization –

guinea pig

40573301

(1986)

Dermal sensitizer n/a
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Quinclorac

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.3100 90-Day oral 

toxicity (Wistar rat)

41063516 (1986)

Unacceptable/nonguideline based on lack of 

analyses of diet 

concentration, 

homogeneity, stability.

0, 1000, 4000 or 12,000 

ppm in diet

M: 0, 76.8, 302, 930 

mg/kg/day

F: 0, 86.7, 358, 1035 

mg/kg/day

NOAEL = 302 mg/kg/day (males) and 358 

mg/kg/day (females)

LOAEL = 930 mg/kg/day (males) and 1035 

mg/kg/day (females) based on decreased body 

weight gain, food consumption and increased 

water intake in males and females; increased 

SGOT, SGPT and focal chronic interstitial 

nephritis in males.

870.3100 90-Day oral 

toxicity 

(B6C3F1/Crl Br 

mouse)

41063519 (1988)

Acceptable/guideline

when considered together 

with 41063519

0 or 500 ppm in diet

0 or 75 mg/kg/day

NOAEL = 75 mg/kg/day (HDT)

LOAEL was not established in this study (> 75 

mg/kg/day)

870.3100 90-Day oral 

toxicity 

(B6C3F1/Crl Br 

mouse)

41063518 (1986)

Acceptable/guideline 

when considered together 

with 41063518

0, 4000, 8000 or 16,000 

ppm in diet

M: 0, 1000, 2202 or 4555 

mg/kg/day 

F: 0, 1467, 2735 or 5953 

mg/kg/day

NOAEL not established in this study (<1000 

mg/kg/day)

LOAEL = 1000 mg/kg/day (males) and 1467 

mg/kg/day (females), based on decreased body 

weight gains. 

870.3200 21-Day dermal 

toxicity (New 

Zealand White 

rabbit)

44342905 (1990)

Acceptable/guideline

0, 200 or 1000 mg/kg/day 

applied to skin daily for 

21 days.

NOAEL = 1000 mg/kg/day (limit dose)

LOAEL not established in this study (> 1000 

mg/kg/day).

870.3700a Prenatal 

developmental in 

(Wistar rat)

41063524 (1987)

Acceptable/guideline

0, 24.4, 146 or 438 

mg/kg/day (gavage)

Maternal NOAEL = 146 mg/kg/day

LOAEL = 438 mg/kg/day based on increased 

mortality, decreased food consumption and 

increased water consumption.

Developmental NOAEL ≥438 mg/kg/day

LOAEL not established in this study (> 438 

mg/kg/day).
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Quinclorac

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.3700b Prenatal 

developmental in 

(Himalayan rabbit)

41063525 (1986), 

41680501 (1990)

Acceptable/guideline

0, 70, 200 or 600 

mg/kg/day (gavage)

Maternal NOAEL = 70 mg/kg/day

LOAEL = 200 mg/kg/day based on decreased 

body weight gain and food consumption (and 

increased water consumption).

Developmental NOAEL = 200 mg/kg/day

LOAEL = 600 mg/kg/day based on increased 

resorption rate, postimplantation loss, 

decreased live fetuses and reduced fetal body 

weight.

870.3800 Reproduction and 

fertility effects

(Wistar rat)

41063526 (1988); 

41874201, -02 (1991, 

1988); 41910001 (1991)

Acceptable/guideline

0, 1000, 4000 or 12,000 

ppm in diet

0, 40, 160 or 480 

mg/kg/day

Parental/Systemic NOAEL = 160 mg/kg/day

LOAEL = 480 mg/kg/day based on reduced 

body weight in both sexes during premating 

and lactation periods.

Reproductive NOAEL = 480 mg/kg/day

LOAEL not established in this study (> 480 

mg/kg/day).

Offspring NOAEL = 160 mg/kg/day

LOAEL = 480 mg/kg/day based on decreased 

pup weight, developmental delays and possible 

marginal effect on pup viability.

870.4300 Combined chronic 

toxicity/ 

carcinogenicity

(Wistar rat)

41063522 (1988); 

42012901, -02 (1991)

Acceptable/guideline

0, 1000, 4000, 8000 or 

12,000 ppm in diet

M: 0, 56, 186, 385 or 487 

mg/kg/day

F: 0, 235, 478 or 757 

mg/kg/day

NOAEL = 385 mg/kg/day (males and 478 

mg/kg/day (females)

LOAEL = 487 mg/kg/day (males) based on 

increased incidence of pancreatic acinar cell 

hyperplasia and 757 (females) based on 

decreased body weight.

Equivocal increase in pancreatic acinar cell 

adenomas in males.

870.4100b Chronic toxicity 

(Beagle dog)

41123201 (1987)

Acceptable/guideline

0, 1000, 4000 or 12,000 in 

diet

M: 0, 34, 142 or 513 

mg/kg/day

F: 0, 35, 140 or 469 

mg/kg/day

NOAEL = 142 mg/kg/day (males) and 140 

mg/kg/day (females)

LOAEL = 513 mg/kg/day (males) and 469 

mg/kg/day (females) based on decreased body 

weight gain and food efficiency, increased liver 

and kidney weights, decreased HgB, RBC, 

MCH and MCV and kidney degeneration.

870.4200 Carcinogenicity

(B6C3F1/Crl Br 

mouse)

41063523 (1988)

Acceptable/guideline

0, 250, 1000, 4000 or 

8000 ppm in diet

M: 0, 37.5, 150, 600 or 

1200 mg/kg/day

NOAEL = 37.5 mg/kg/day

LOAEL = 150 mg/kg/day based on decreased 

body weight in males and females.

No evidence of carcinogenicity.
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Quinclorac

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870. 5100 Bacterial reverse 

gene mutation

Ames assay S. 

typhimurium

41063527 (1984)

Acceptable/guideline

Dose range 0 to 5000 

μg/plate with and without 

S9

Negative up to the limit dose (5000 μg/plate) 

with or without S9 in S. typhimurium strains

TA98, TA100, TA1535, TA1537

870.5100 Bacterial reverse 

gene mutation

S. 

typhimurium/E.coli

41063528 (1988) 

Acceptable/guideline

Dose range 0 to 5000 

μg/plate with and without 

S9

Negative up to the limit dose (5000 μg/plate) 

with or without S9 in S. typhimurium strains 

TA98, TA100, TA1535, TA1537 and E. coli

strain WP2 uvrA

870.5300 In vitro mammalian 

forward gene 

mutation, CHO 

cells/HGPRT locus

41680503 (1989)

Acceptable/guideline

Dose range 0 to 2150 

μg/mL with or without S9

Negative for gene mutations up to cytotoxic 

doses (2000 μg/mL) with or without S9.

870.5375 In vitro mammalian 

chromosome 

aberration assay, 

human 

lymphocytes

41076103 (1986)

Acceptable/guideline

Dose range 125 to 1500 

μg/mL without S9 and 

250 to 2500 μg/mL with 

S9

Positive for chromosomal aberrations but only 

at cytotoxic concentrations (2000 μg/mL with 

S9 and 1000 μg/mL without S9).

870.5385 Cytogenetics – in 

vivo mouse 

micronucleus assay

41063530 (1989)

Acceptable/guideline

Single gavage doses up to 

1000 mg/kg

Negative in male and female NMRI mice at all 

doses up to limit dose (1000 mg/kg). Mid and 

high dose groups showed clinical signs of 

toxicity (irregular breathing, apathy, 

piloerection) but no toxicity to target cell was 

observed.

870.5550 Unscheduled DNA 

synthesis in 

primary rat 

hepatocytes

41063531 (1986)

Acceptable/guideline

Dose range 0 to 1520 

μg/mL

Negative up to cytotoxic dose (1520 μg/mL).

870.7485 Metabolism and 

pharmacokinetics

(rat) -

biodisposition

41063533 (1987)

Acceptable/guideline

Single gavage doses of 15 

or 600 mg/kg of 14Cquinclorac; 14 daily 

gavage doses of unlabeled 

quinclorac following by a 

single dose of 14Cquinclorac

Quinclorac was rapidly absorbed and 

eliminated primarily in the urine (91-98% of 

dose) with small amounts (1-4%) eliminated in 

the feces by day 5 after dosing. No 

radioactivity was detected in exhaled air. 
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Table A.2.2 Subchronic, Chronic and Other Toxicity Profile – Quinclorac

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.7485 Metabolism and 

pharmacokinetics

(rat) – Biliary 

excretion studies

41063533 (1987)

Acceptable/guideline

Single gavage doses of 15 

or 600 mg/kg 14Cquinclorac

Biliary excretion was significant (11.5 to 14.5% 

of dose) at 600 mg/kg but was reabsorbed from 

the intestine and eliminated in the urine.

870.7485 Metabolism and 

pharmacokinetics

(rat) – Plasma level 

studies

41063533 (1987)

Acceptable/guideline

Single gavage doses of 

15, 100, 600 or 1200 

mg/kg

Multiple gavage doses of 

15 or 600 mg/kg/day 14Cquinclorac for 7 days.

Mean residues were detected in plasma 30 

minutes postdosing following all dose 

regimens. Quinclorac is poorly metabolized: 

most of radioactivity was the parent compound. 

Peak plasma levels of radioactivity after 7 days 

of dosing at 600 or 1200 mg/kg/day were 

observed between 7 to 48 hrs postdosing.

870.7485 Metabolism and 

pharmacokinetics

(rat) – Tissue level 

studies

41063533 (1987)

Acceptable/guideline

Multiple gavage doses of 

14C-quinclorac 15 or 1200 

for 7 days.

The highest concentrations of radioactivity in 

tissues were found at 30 minutes after the final 

dose for low and high doses. Significant tissue 

levels were not observed (≤0.45% of dose), 

with highest levels observed in the thyroid, 

bone marrow and adrenal. Tissue levels were 

slightly greater in females.

870.7800 Immunotoxicity

female C57BL/6 J 

Rj mice (8/group) 

48346101 (2010)

Acceptable/guideline

0 (control), 500, 1500, or 

5000 ppm (equivalent to 

0, 176, 439, or 1760 

mg/kg bw/day, for 28 

days

Immunotoxicity NOAEL is 5000 ppm 

(equivalent to 1760 mg/kg/day, the highest 

dose tested and above the limit dose); 

LOAEL was not established.

A.3 Hazard Identification and Endpoint Selection

A.3.1 Acute Reference Dose (aRfD) - Females age 13-49

Study Selected: Developmental toxicity study in rabbits 

MRID No.: 41063525; 41680501

Executive Summary: In a developmental toxicity study (MRID# 41063525), quinclorac (98.3% 

a.i.) was administered to fifteen female Himalayan Rabbits by gavage at dose levels of 0, 70, 

200, or 600 mg/kg/day from gestational days 7–19, inclusive.

Maternal toxicity, observed at 200 mg/kg/day, was manifested as decreased body weight gain 

(36%) and food consumption (13%) during the dosing period. Additional findings noted at 600

mg/kg/day, included increased water consumption (7% over entire gestation), increased 
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incidence of clinical signs (reduced/no defecation, diarrhea, apathy and poor general state) and 

mortality and discoloration of the kidney. The maternal LOAEL is 200 mg/kg/day, based on 

decreased body weight gains and food consumption. The maternal NOAEL is 70 

mg/kg/day.

Developmental toxicity, observed at 600 mg/kg/day consisted of increased rate of resorption and 

post-implantation loss, a decrease in the number of live fetuses, and reduced fetal body weight. 

The NOAEL for developmental toxicity is 200 mg/kg/day.

Dose and Endpoint for Risk Assessment: Developmental NOAEL= 200 mg/kg/day based on 

increased rate of resorption and post-implantation loss, a decrease in the number of live fetuses, 

and reduced fetal body weight at 600 mg/kg/day (LOAEL). 

Comments about Study/Endpoint: The developmental effects are presumed to occur after a 

single exposure (dose) and thus were considered to be appropriate for this (acute) risk 

assessment. This dose/endpoint is applicable only to Female 13 to 49 years old.

Uncertainty Factor (UF): 100 (10 x for inter-species extrapolation and 10x for intra-species 

variability, FQPA SF = 1x).

 

 =

200 mg/kg/day (NOAEL)

 ()

= 2.0 mg/kg

 =

2 mg/kg/day (aRfD)

 ( )

= 2.0 mg/kg

A.3.2 Acute Reference Dose (aRfD) - General Population

An endpoint for acute dietary exposure to the general population was not selected because there 

was no single dose endpoint available in the database that was appropriate for this scenario 

A.3.3 Chronic Reference Dose (cRfD) `

Study Selected: Oncogenicity Feeding Study in Mice 

MRID No.: 41063523

Executive Summary: In a carcinogenicity study (MRID# 41063523), B6C3F1/Crl Br mice (60 

sex/dose) were administered via diets with Quinclorac (97.4 or 98.3% a.i) at dose levels of 0, 

250, 1000, 4000, or 8000 ppm (equivalent to 0, 37.5, 150, 600 or 1200 mg/kg/day) for 6 months 

or 78 weeks. Ten mice were terminated at 6 months. The remainders were continued on the test 

material for 18 months.

At the end of 13 weeks, body weights in males and females receiving 8000 ppm were 

significantly lower than controls by 9.6% and 7.4%, respectively. Body weights in males and 

females receiving 1000, 4000, and 8000 ppm for 78 weeks were significantly lower than controls 
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(7.9 to 15.9% for males; 14.3 to 17.9 for females. Treatment-related body weight reductions 

compared to controls were also noted in satellite males and females receiving 4000 and 8000 

ppm for 6 months. Absolute liver weights were significantly reduced in male and female mice 

receiving 8000 ppm for 78 weeks, but there was no effect on liver-to-body weight ratio. 

Absolute kidney weights were decreased in males receiving 1000, 4000, and 8000 ppm and in 

females receiving 4000 and 8000 ppm for 78 weeks. Relative kidney weights were decreased in 

males receiving 1000, 4000, and 8000 ppm for 78 weeks. Dose-related increases in relative 

brain weights seen in males and females receiving 1000, 4000, and 8000 ppm. Absolute liver 

weights were also reduced in males receiving 4000 and 8000 ppm for 6 months, while absolute 

kidney weights were reduced in all treated males. A slight decrease in hematocrit values was 

noted in males and females receiving 8000 ppm for 6 months, but not 78 weeks. Effects on other 

hematological parameters were not of biological significance. There was no effect of dosing on 

mortality, food consumption, or clinical signs. The LOAEL is 1000 ppm (150 mg/kg/day) based 

on effects on body weight. The NOAEL is 250 ppm (37.5 mg/kg/day). A maximum tolerated 

dose (MTD) was approached based on decreased body weights in males and females receiving 

8000 ppm.

No evidence of histopathological or neoplastic lesions attributable to administration of any dose 

of Quinclorac was found in any tissue of any mouse.

Dose and Endpoint for Establishing RfD: NOAEL = 37.5 mg/kg/day based on decreased 

body weights seen at 150 mg/kg/day (LOAEL).

Comments about Study/ Endpoint: The endpoint selected from the mouse carcinogenicity 

study is appropriate for both the population and the duration of exposure. The NOAEL from this 

study is the lowest NOAEL in the database and therefore protective of all other effects.

Uncertainty Factor(s): 100 (10 x for inter-species extrapolation and 10x for intra-species 

variability; FQPA SF = 1X).

 =

37.5 mg/kg/day (NOAEL)

 ()

= 0.38 mg/kg/day

 =

0.375 mg/kg/day (cRfD)

 ( )

= 0.38 mg/kg/day

A.3.4 Incidental Oral Exposure (Short- and Intermediate-Term)

Study Selected: Developmental toxicity study in rabbits. 

MRID Nos.: 41063525; 41680501

Executive Summary: See Appendix A, §870.3700b
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Dose and Endpoint for Risk Assessment: Maternal NOAEL= 70 mg/kg/day based on 

decreased body weight gains and food consumption accompanied with increased water 

consumption at 200 mg/kg/day (LOAEL). 

Comments about Study/Endpoint: This endpoint of toxicity occurred after short exposures to 

quinclorac and is suitable for this exposure scenario.

A margin of exposure (MOE) of 100 is applied to account for inter-species extrapolation (10x) 

and for intra-species variability (10x). 

A.3.5 Dermal Exposure (Short-, Intermediate- and Long-Term)

A dermal endpoint was not selected because an appropriate endpoint was not available (no 

dermal toxicity was seen at the limit dose of 1000 mg/kg/day in a 21-day dermal toxicity study). 

Also, there are no susceptibility concerns.

A.3.6 Inhalation Exposure (Short-, Intermediate- and Long-Term) 

A.3.7 Inhalation Exposure (Short and Intermediate-Term)

Selected Study: Developmental toxicity study in rabbits. 

MRID Nos.: 41063525; 41680501

Executive Summary: See Appendix A, §870.3700b

Dose and Endpoint for Risk Assessment: Maternal NOAEL= 70 mg/kg/day based on 

decreased body weight gains and food consumption accompanied with increased water 

consumption at 200 mg/kg/day (LOAEL). 

Comments about Study/Endpoint: This endpoint of toxicity occurred after short exposures to 

quinclorac and is suitable for this exposure scenario.

A margin of exposure (MOE) of 100 is applied to account for inter-species extrapolation (10x) 

and for intra-species variability (10x).

A.3.7 Inhalation Exposure (Long-Term)

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

 
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A.4 Executive Summaries

A.4.1 Subchronic Toxicity

870.3100 90-Day Oral Toxicity - Rat

In a subchronic toxicity study (MRID 41063516), Quinclorac (96.5% a.i.) was administered to 

10 Wistar Chhb-THOM (SPF) rats/sex/dose in diet, at dose levels of 0, 1000, 4000, or 12000 

ppm (0, 76.8, 302.3 or 929.9 mg/kg/day for males and 0, 86.7, 358.0 or 1035.4 mg/kg/day for 

females). There were no deaths occurred. No compound related clinical signs of toxicity were 

observed. The LOAEL is 12,000 ppm (males 929.9 and females 1035.4 mg/kg/day), based on 

decreases in body weight gain, food consumption and an increase in water intake in males and 

females, and decrease in monocytes in female, increases in SGOT and SGPT in males, and 

pathological changes in kidneys of males (slight to minimal focal chronic interstitial nephritis. 

The NOAEL is 4000 ppm (males 302.3 and females 358.0 mg/kg/day).

This subchronic toxicity study is classified unacceptable/non-guideline due to lack of 

information on the purity of the test material and information on stability and homogeneity of the 

test substance in the diet.

870.3100 90-Day Oral Toxicity - Mouse

In a subchronic toxicity study (MRID 41063518), Quinclorac (98.29% a.i.) was administered to 

10 B6C3F1/Crl BR mice/sex/dose in diet, at dose levels of 0, 4000, 8000, or 16000 ppm (0, 

1000, 2202 or 4555 mg/kg/day for males and 0, 1467, 2735 or 5953 mg/kg/day for females). No 

deaths occurred. No compound related clinical signs of toxicity were observed. At 8000 and 

16000 ppm there was an increase in water intake in males and females and BUN in males. There 

was decreased kidney weight in males and females and relative kidney weight in males in the 

16,000 ppm group. At 4000 ppm there was decreased body weight gain in males and females. 

The LOAEL is 4,000 ppm (males 1,000 and females 1467 mg/kg/day), based on decreases in 

body weight. The NOAEL was not established. 

This subchronic toxicity study is classified Acceptable/non- guideline requirement for a 

subchronic oral study (82-1) in mice. However taken with MRID 41063519, it is acceptable/ 

guideline.

In another subchronic toxicity study (MRID 41063519), Quinclorac (98.29% a.i.) was 

administered to 10 B6C3F1/Crl BR mice/sex/dose in diet, at dose levels of 0 or 500 ppm (75 

mg/kg/day, HDT). No deaths occurred. No compound related clinical signs of toxicity were 

observed. Females in the 500 ppm group had slightly (although statistically significant) reduced 

body weights when compared to controls on day 98. This decrease was minimal and is not 

believed to be compound related since body weights were not significantly different at any other 

time intervals. The NOAEL is 500 ppm (75 mg/kg/day).

This subchronic toxicity study is classified Unacceptable because only one dose level was tested. 

However taken with MRID 41063518, it is acceptable /guideline.
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870.3150 90-Day Oral Toxicity - Dog

The data requirement for a dog 90-day subchronic oral toxicity is satisfied by the 1-year dog 

chronic oral study.

870.3200 21/28-Day Dermal Toxicity – Rabbit

In a twenty-one day dermal toxicity study (MRID 44342905), Quinclorac (98.29% a. I.) in 0.5%

carboxymethyl cellulose was applied dermally to 5 New Zealand White (KFM) albino 

rabbits/sex/dose at dose levels of 0, 40, 200 and 1000 mg/kg/day for 7 days a week for 3 weeks. 

The hair was clipped from the dorsal surface prior to treatment and once a week during the study. 

Test material was applied daily for 3 weeks to an area of skin approximately 10% of the total 

body surface area on the back of each rabbit and covered with a semi-occlusive gauze. After 6 

hour exposure, the excess test material was removed from the treated area with a luke-warm 

water and kept open until next application. Vehicle control group received 2 ml/kg b.w of 0.5% 

carboxymethyl cellulose in water, while test groups received suspension of test material in 

aqueous 0.5% carboxymethyl cellulose (2 ml/kg/b.w). There was no treatment-related clinical 

observations, changes in body weight gain, food consumption, histopathologic findings or 

hematologic or blood chemistry parameters after a 21 day (7 days/week) repeated application of 

Quinclorac at a nominal concentrations of 0, 40, 200 or 1000 mg/kg/day in 0.5% carboxymethyl 

cellulose. The limit dose is 1000 mg/kg/day. No mortality occurred at any dose level tested. No 

local skin irritation was reported during the study. The NOAEL ≥1000 mg/kg/day, Limit Dose, 

(HDT; males and females). The LOAEL >1000 mg/kg/day (HDT; males and females).

This study is classified as Acceptable/Guideline and does satisfy the guideline requirements for a 

21-day repeated dermal toxicity study in rabbits (82-2).

870.3465 90-Day Inhalation – Rat

The requirement of a 28-day inhalation toxicity study was waived based on low volatility, low 

acute inhalation toxicity and large extrapolated inhalation MOE (D376603, 23 September 2010).

A.4.2 Prenatal Developmental Toxicity

870.3700a Prenatal Developmental Toxicity Study - Rat

In a developmental toxicity study (MRID # 41063524), Quinclorac (96.5% a.i.) was 

administered to twenty-five female Wistar rats by gavage at dose levels of 0, 24.4, 146, and 438 

mg/kg/day from gestational days 6-15, inclusive. Maternal toxicity, observed at 438 mg/kg/day, 

was manifested as decreased food consumption (10-15%) and increased water consumption (31-

54%) during the dosing and/or gestation period as well as mortality. The maternal LOAEL is 

438 mg/kg/day, based on decreased food consumption, increased water consumption and 

mortality. The maternal NOAEL is 146 mg/kg/day. No developmental toxicity was observed. 

The LOAEL for developmental toxicity is >436 mg/kg/day. The developmental NOAEL is ≥436 

mg/kg/day.
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This study is classified as Acceptable/Guideline and satisfies the guideline requirement for a 

developmental toxicity study in rats.

870.3700b Prenatal Developmental Toxicity Study - Rabbit

In a developmental toxicity study (MRID# 41063525), Quinclorac (98.3% a.i.) was administered 

to fifteen female Himalayan Rabbits by gavage at dose levels of 0, 70, 200, or 600 mg/kg/day

from gestational days 7–19, inclusive. Maternal toxicity, observed at 200 mg/kg/day, was 

manifested as decreased body weight gain (36%) and food consumption (13%) during the dosing 

period. Additional findings noted at 600 mg/kg/day, included increased water consumption (7% 

over entire gestation), increased incidence of clinical signs (reduced/no defecation, diarrhea, 

apathy and poor general state) and mortality and discoloration of the kidney. The maternal 

LOAEL is 200 mg/kg/day, based on decreased body weight gains and food consumption. The 

maternal NOEL is 70 mg/kg/day. Developmental toxicity, observed at 600 mg/kg/day consisted 

of increased rate of resorption and post-implantation loss, a decrease in the number of live 

fetuses, and reduced fetal body weight. The NOAEL for developmental toxicity is 200 

mg/kg/day. This study is classified as Acceptable/Guideline and satisfies the guideline 

requirement for a developmental toxicity study (83-3b) in rabbits.

A.4.3 Reproductive Toxicity

870.3800 Reproduction and Fertility Effects - Rat

In a 2-generation reproduction study (MRID # 41063526), Quinclorac (≥97.3% a.i.) was 

administered to Wistar rats (24/sex/group) at dietary levels of 0, 1,000, 4,000 or 12,000 ppm (0, 

40, 160 or 480 mg/kg/day, respectively).

Parental toxicity: Evidence of toxicity was observed in the parental rats at 12,000 ppm (480 

mg/kg/day). Fl males showed reduced mean body weight during premating, which largely 

reflected their decreased weights as pups at weaning (at week 0, -24%, p<0.0l, becoming less 

pronounced at week 18, -6% below controls, p<0.05). F0 males showed no effects. F0 females 

showed a small but statistically significant decrease in mean body weight at Week 24 of 

premating (-4%, p<0.05) but not at earlier times. F1 females had decreased body weights during 

premating (at Week 18, -12%; p<0.01): as with males, part of the decrease reflected smaller 

weights at weaning. During gestation, decreases of about -6% in mean body weight at Day 20 

were observed for the F0 females in the second mating (p<0.01) and the Fl females in their only 

mating (p<0.05). However, in the second mating of F0 females, there was no significant effect. 

The F0 (first mating only) and Fl females showed reduced body weights during part or all of 

lactation (up to -10% below controls). In addition to body weight changes, an increased 

incidence of interstitial nephritis was observed in F0 and Fl females. The parental systemic 

toxicity LOAEL is 12,000 ppm (480 mg/kg/day), based on decreased body weight during

premating and lactation. The NOAEL is 4000 ppm (160 mg/kg/day).

Reproductive toxicity: No effects on reproductive parameters were observed. The reproductive 

toxicity NOAEL is 12,000 ppm (480 mg/kg/day). A reproductive toxicity LOAEL was not 

established (>480 mg/kg/day).
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Offspring toxicity: At 12,000 ppm (480 mg/kg/day), the major effect on pup growth and 

development was observed during lactation. Decreased pup weights were observed in male and 

female Fl and F2 pups during lactation (at Day 21 of lactation, 15-26% below controls; all 

generations p<0.0 1) and delayed physical development (delayed pinna unfolding and eye 

opening) was also observed. Decreased pup weight at Lactation Day 0 was seen only in the F2

male and female pups (approximately 7% below controls), a dose also associated with a slight 

decrease in maternal weight during gestation. Slightly decreased pup viability and survival were 

reported; however, these effects were marginal (<6%), not seen in all offspring generations and 

did not achieve statistical significance. The relationship to treatment of this finding is considered 

equivocal. The offspring LOAEL is 12,000 ppm (480 mg/kg/day), based on effects on pup 

growth with a possible marginal effect on pup viability. The offspring NOAEL is 4000 ppm (160 

mg/kg/day).

This study is classified as Acceptable/guideline and satisfies the guideline requirement for a 

multigeneration reproductive toxicity study in the rodent (870.3800).

A.4.4 Chronic Toxicity

870.4100a (870.4300) Chronic Toxicity – Rat

The combined chronic/carcinogenicity study satisfies this requirement. 

870.4100b Chronic Toxicity - Dog

In a 1-year feeding study in dogs (MRID 41123201), Quinclorac (97.4% a.i.) was administered 

to groups of 6 male and 6 female beagle dogs at dietary levels of 0, 1000, 4000 or 12000 ppm 

(equivalent to 0, 34, 142, or 513 mg/kg/day for males and 0, 35, 140, or 469 mg/kg/day for 

females) for 12 months. No effect on mortality was observed. Administration of 12000 ppm 

resulted in lower mean body weight, compared with control, reduced body weight gain and an 

adverse effect on food efficiency. There was a marginal reduction of body weight gain and food 

efficiency in male dogs fed 4000 ppm of test substance. In male dogs fed 12000 ppm of test 

substance, there were significant (<0.01) treatment-related reductions in hemoglobin 

concentration, erythrocyte count, and hematocrit, mean corpuscular volume (MCV) and mean 

corpuscular hemoglobin (MCH) values. In females fed 12000 ppm of test substance, significant 

reductions (p <0.05 or p <0.01) were seen in hemoglobin concentration, MCH, and MCV at all 

study intervals (weeks 13, 26, and 52), hematocrit at weeks 26 and 52 and erythrocyte count at 

week 26. In females fed 4000 ppm test substance, significant reductions (p <0.05) were seen at 

week 26 in hemoglobin concentration, erythrocyte count, and hematocrit. Administration of 

12000 ppm of test substance resulted in decreases in a number of clinical chemistry parameters; 

however, significant (p <0.01) changes were noted only for creatinine, calcium, and albumin. 

However, it should be noted that, in most cases, clinical adverse effects are only associated with 

increased values for these parameters. At the 12000 ppm dose level, increase in absolute (p <0.01 

for males) and relative liver weights (p <0.01 for both males and females) were observed for 

both sexes. Relative liver weights also were significantly increased (p <0.05) in females of the 

4000 and 1000 ppm groups. Relative kidney weights were significantly increased (p <0.01) in 
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both males and females of the 12000 ppm group and in males of the 4000 ppm group. There 

were no histopathologic correlates to account for the increased organ weights. Histopathologic 

findings in the liver were limited to an increase in focal mononuclear infiltration and to single 

cell necrosis in two dogs in the 12000 ppm group. Hydropic degeneration of the kidney was seen 

in two males and two females of the 12000 ppm group.

The LOAEL is 12000 ppm (513 mg/kg/day-males, 469 mg/kg/day- females) based on the 

reduced body weight gain, adverse effect on food efficiency, hematological and clinical 

chemistry values, increased liver and kidney weights, and microscopic findings. The NOAEL is 

4000 ppm (142 mg/kg/day for males and 140 mg/kg/day for females).

This study is classified as Acceptable/Guideline and satisfies the guideline requirement for a 

feeding study (83-1) in dogs.

A.4.5 Carcinogenicity

870.4200a Carcinogenicity Study - rat

In a combined chronic toxicity/carcinogenicity study (MRID# 41063522), Wistar (chbb-THOM) 

rats (80/sex/group) were administered via diets with Quinclorac (97.4% a.i.) at dose levels of 0, 

1000, 4000, 8000, or 12000 ppm (equivalent to 0, 56, 186, 385, or 487 mg/kg/day for males and 

0, 60, 235, 478, or 757 mg/kg/day for females, respectively). Ten rats/sex/group were terminated 

at 12 months. The remainders were continued on the test material for 24 months. Body weights 

were slightly reduced in females received 12000 ppm when compared to the control. No effects 

were seen on survival, food consumption, clinical signs of toxicity, clinical laboratory findings, 

organ weight, or gross or histologic findings. For females, the LOEL was 12000 ppm based on 

slight decreases in mean body weight and the NOEL was 8000 ppm. For males, the LOEL was 

not established and the NOEL was 12000 ppm (the highest dose tested). This study was 

originally classified as supplementary (upgradeable) because a maximum tolerated dose (MTD) 

was not established for the carcinogenicity part of the study; in addition, there was a probability

of misdiagnosis of microscopic findings caused by tabulation of NAD (no abnormalities 

detected) for tissues in several animals with severe postmortem autolysis. 

Additional data (MRID# 42012901, 42012902) were submitted to the Agency in which 

adequately addressed the deficiencies described above. For chronic toxicity, the LOEL was 

estimated to be 12000 ppm (487 mg/kg/day for males and 757 mg/kg/day for females) based on 

slight decrease in body weight in females and an increase in acinar cell hyperplasia of the 

pancreas in males. The NOEL was 8000 ppm (385 mg/kg/day for males and 478 mg/kg/day for 

females). For carcinogenicity, the data indicate an increase in acinar cell hyperplasia of the 

pancreas in males at 12000 ppm (35%) when compared to controls (5.7%). In addition, there was 

an increase in the incidence of acinar cell adenoma of the pancreas in males in the 12000 ppm 

group (20%) when compared to the control (1.4%). 

The study was upgraded to acceptable and satisfies guideline requirement for a combined 

chronic toxicity/carcinogenicity study in rats (83-5).

870.4200b Carcinogenicity (feeding) - Mouse
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In a carcinogenicity study (MRID# 41063523), B6C3F1/Crl Br mice (60 sex/dose) were 

administered via diets with Quinclorac (97.4 or 98.3% a.i) at dose levels of 0, 250, 1000, 4000, 

or 8000 ppm (equivalent to 0, 37.5, 150, 600 or 1200 mg/kg/day) for 6 months or 78 weeks. Ten 

mice were terminated at 6 months. The remainders were continued on the test material for 18 

months. At the end of 13 weeks, body weights in males and females receiving 8000 ppm were 

significantly lower than controls by 9.6% and 7.4%, respectively. Body weights in males and 

females receiving 1000, 4000, and 8000 ppm for 78 weeks were significantly lower than controls 

(7.9 to 15.9% for males; 14.3 to 17.9 for females. Treatment-related body weight reductions 

compared to controls were also noted in satellite males and females receiving 4000 and 8000 

ppm for 6 months. Absolute liver weights were significantly reduced in male and female mice 

receiving 8000 ppm for 78 weeks, but there was no effect on liver-to-body weight ratio. 

Absolute kidney weights were decreased in males receiving 1000, 4000, and 8000 ppm and in 

females receiving 4000 and 8000 ppm for 78 weeks. Relative kidney weights were decreased in 

males receiving 1000, 4000, and 8000 ppm for 78 weeks. Dose-related increases in relative 

brain weights seen in males and females receiving 1000, 4000, and 8000 ppm. Absolute liver 

weights were also reduced in males receiving 4000 and 8000 ppm for 6 months, while absolute 

kidney weights were reduced in all treated males. A slight decrease in hematocrit values was 

noted in males and females receiving 8000 ppm for 6 months, but not 78 weeks. Effects on other 

hematological parameters were not of biological significance. There was no effect of dosing on 

mortality, food consumption, or clinical signs. The LOEL is 1000 ppm (150 mg/kg/day) based 

on effects on body weight. The NOEL is 250 ppm (37.5 mg/kg/day). A maximum tolerated 

dose (MTD) was approached based on decreased body weights in males and females receiving 

8000 ppm.

No evidence of histopathological or neoplastic lesions attributable to administration of any dose 

of Quinclorac was found in any tissue of any mouse.

This study is classified as Acceptable/Guideline and satisfies the guideline requirement for a 

carcinogenicity study (83-2) in mice.

A.4.6 Mutagenicity

Gene Mutation

870. 5100 

Bacterial reverse gene mutation

41063527

Acceptable/Guideline

Negative up to the limit dose (5000 μg/plate) with or without 

S9 in S. typhimurium strains TA98, TA100, TA1535, 

TA1537

870. 5100 

Bacterial reverse gene mutation

41063528

Acceptable/Guideline

Negative up to the limit dose (5000 μg/plate) with or without 

S9 in S. typhimurium strains TA98, TA100, TA1535, 

TA1537 and E. coli strain WP2uvrA
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Cytogenetics

OPPTS 870.5385 

In vivo bone marrow cytogenic 

assay

MRID 41063530.

Acceptable/Guideline

Quinclorac was not clastogenic in this in vivo test. Negative 

in male and female NMRI mice at all doses up to limit dose 

(1000 mg/kg). Mid and high dose groups showed clinical 

signs of toxicity (irregular breathing, apathy, piloerection) 

but no toxicity to target cell was observed.

OPPTS 870.5395 

In vivo micronucleus assay in 

mice. MRID 41063529.

Acceptable/Guideline

Quinclorac did not induce clastogenic or aneugenic at any 

dose (500, 1000 or 2000 mg/kg) or sacrifice time. Toxic signs 

of irregular breathing, apathy, and piloerection were noted in 

the mid- and high-dose groups.

Other Genotoxicity

870.5300, In vitro mammalian 

forward gene mutation, CHO 

cells/HGPRT locus

MRID 41680503

Acceptable/guideline

Negative for gene mutations up to cytotoxic doses (2000 

μg/mL) with or without S9.

870.5300, In vitro mammalian 

chromosome aberration assay, 

human lymphocytes

MRID 41076103

Acceptable/guideline

Positive for chromosomal aberrations but only at cytotoxic 

concentrations (2000 μg/mL with S9 and 1000 μg/mL

without S9).

870.5550, Unscheduled DNA 

synthesis in primary rat 

hepatocytes MRID 41063531

Acceptable/guideline

Negative up to cytotoxic dose (1520 μg/mL).

A.4.7 Neurotoxicity

870.6100 Delayed Neurotoxicity Study – Hen 

Not required.

870.6200 Acute Neurotoxicity Screening Battery -

Waived (HASPOC TXR 0056385)
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870.6200 Subchronic Neurotoxicity Screening Battery

Waived (HASPOC TXR 0056385)

870.6300 Developmental Neurotoxicity Study

HED HIARC did not recommend a DNT study. (TXR 0012902)

A.4.8 Metabolism

870.7485 Metabolism - Rat

The metabolism of quinclorac ([2,3,4-

14C)3,7—dichloro-8- quinolinecarboxylic acid) following 

oral administration was studied extensively in male and female CD rats (MRID 41063533). The 

compound was rapidly absorbed and eliminated in the urine following administration of single 

oral doses of [14C] quinclorac at 15 or 600 mg/kg and at 15 mg/kg after the animals were dosed 

with unlabeled quinclorac at 15 mg/kg/day for 14 days. Elimination in the urine 5 days after 

dosing accounted for 91 to 98% of the dose with only 1 to 4% eliminated in the feces. No 

radioactivity was detected in expired air. Biliary excretion was significant (11.5 to 14.5% of the 

dose) in animals receiving 600 mg/kg. However, most of this radioactivity was reabsorbed from 

the intestines and eliminated in the urine. Most of the radioactivity in the bile is associated with 

the glucuronide conjugate of quinclorac. The conjugate is apparently hydrolyzed in the intestines 

and reabsorbed. Almost all the radioactivity in the urine is unchanged quinclorac. Radioactive 

tissue residue levels 5 days after dosing were dose-dependent. Results from these and other 

(whole-body autoradiography and time-course) studies indicate that quinclorac may accumulate 

in the adrenal glands, bone marrow, thyroid, squamous epithelium of the non-fundic stomach, 

and ovaries. In 7-day time-course studies (oral gavage at 15 mg/kg/day or dietary at about 1,000 

mg/kg/day) maximum 14C residue levels were detected 30 minutes after the final dose; thereafter, 

residue levels decreased with time. Mean 14C residues in plasma were also detected at 30 

minutes in animals receiving single oral doses of 15, 100, or 600 mg/kg or 15 mg/kg/day for 7 

days. Elimination was biphasic with half-lives of 3 to 4 hours for the rapid phase at the low doses 

and a half-life of about 13 hours at 600 mg/kg. Peak plasma levels of radioactivity in animals 

receiving higher doses (1200 mg/kg or 600 mg/kg/day for 7 days) were noted for 7 to 48 hours 

postdosing: saturation kinetics were also noted at these higher doses. These studies are 

acceptable and fulfill EPA’s guidelines series 85-1.

870.7600 Dermal Absorption - Rat

Dermal absorption studies are not available.

A.4.9 Immunotoxicity

870.7800 Immunotoxicity

In an immunotoxicity study (MRID 48346101), Quinclorac (BAS 514 H, 99.9% a.i., Batch# 

479-480) was administered to female C57BL/6 J Rj mice (8/group) in the diet at dose levels of 0 
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(control), 500, 1500, or 5000 ppm (equivalent to 0, 176, 439, or 1760 mg/kg bw/day, 

respectively) for 28 consecutive days. Animals in the positive control group (8/group) received 

cyclophosphamide by gavage at a dose of 10 mg/kg/day throughout the study. Six days before 

necropsy, animals in all groups were immunized with a suspension of sheep red blood cells 

(4x108 SRBC/mL) by intravenous injection (0.5 mL/animal dose volume). All animals were 

evaluated for mortality, clinical signs, body weight changes, food consumption, and gross 

pathology. Immunotoxicity was assessed using an Enzyme-Linked Immunosorbent Assay

(ELISA) approach that measured the concentration of serum anti-SRBC immunoglobulin M 

(IgM). The absolute and relative (to terminal body weight) organ weights of the spleen and 

thymus were determined at necropsy. 

There were no treatment related effects on mortality, clinical signs, body weight changes, food 

consumption, organ weights, or gross pathology at any dose concentration that were considered 

treatment related. 

The systemic toxicity NOAEL is 5000 ppm (equivalent to 1760 mg/kg bw/day); the LOAEL was 

not established, tested above the limit dose.

For immunotoxicity, there were no treatment-related effects on serum anti-SRBC IgM antibody 

levels as measured by an ELISA, or thymus and spleen weights at any diet concentration. High 

inter-individual variability was seen in the treatment and vehicle control groups. Examination of 

individual animal data did not show any trend or distribution that would demonstrate significant 

suppression of the anti-SRBC IgM response. The mean IgM result from positive control group 

was 79.6% lower than the vehicle control group, showing it was valid for evaluating immunosuppression. The positive control group confirmed the ability of the test system to detect 

immuno-suppressive effects and confirmed the validity of the study design.

A Natural Killer (NK) cell activity assay was not performed in this study. The toxicology

database for quinclorac does not reveal any evidence of treatment-related effects on the immune 

system. The overall weight of evidence suggests that this chemical does not directly target the 

immune system. Under HED guidance, a NK cell activity assay is not required at this time.

Under conditions of this study, the immunotoxicity NOAEL is 5000 ppm (equivalent to 1760 

mg/kg/day, the highest dose tested and above the limit dose); the LOAEL was not established.

This immunotoxicity study is classified as acceptable/guideline and satisfies the guideline 

requirement for an immunotoxicity study (OPPTS 870. 7800) in rodents.

A.4.9 Special/Other Studies (optional section)

None.
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Appendix B. Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data, which include studies from 

the Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural Handler 

Exposure Task Force (AHETF) database; the Outdoor Residential Exposure Task Force 

(ORETF) database; and the Agricultural Re-entry Task Force (ARTF) database are subject to 

ethics review pursuant to 40 CFR 26, have received that review, and are compliant with 

applicable ethics requirements. For certain studies that review may have included review by the 

Human Studies Review Board. Descriptions of data sources as well as guidance on their use can 

be found at http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html.
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Appendix C: International Residue Limits 

Quinclorac (PC Code 128974; Date of Request 7/26/12)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex

40 CFR 180.463

Plant/Livestock: quinclorac, 3,7-dichloro8-quinolinecarboxylic acid

3,7-dichloro8-

quinolinecarb

oxylic acid

None

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

US Canada Mexico1 Codex

Barley, grain 2.0 2.0

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

Grass, forage 150

Grass, hay 130

Hog, fat 0.7 0.05

Hog, meat byproducts 0.05 0.05

Hog, meat 0.05 0.05

Horse, fat 0.05 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 0.05 0.05

Poultry, meat 0.05 0.05

Rice, bran 15.0

Rice, grain 5.0 5.0

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
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Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex

Proposed MRLs 

Low growing berries, except 

strawberries, subgroup 13-

07H

1.5

Rhubarb 0.5

MRLs With No US Equivalent

Barley, bran 3.5

Completed by: M. Negussie; 07/31/2012

1 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

(b) Section 18 emergency exemptions . Time-limited tolerances are established for residues of 

the herbicide quinclorac, including its metabolites and degradates, in or on the commodity in the 

table in this paragraph. Compliance with the tolerance level specified in this paragraph is to be 

determined by measuring only quinclorac, 3,7-dichloro-8-quinolinecarboxylic acid, in or on the 

commodity. The tolerance expires and is revoked on the date specified in the table in this 

paragraph.

Commodity Parts per million Expiration/revocation date

Cranberry 15.0 12/31/12