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Contents

I. INTRODUCTION............................................................................................................. 3

II. SCIENTIFIC ASSESSMENTS ....................................................................................... 4

A. HUMAN HEALTH RISK ASSESSMENT ..................................................................... 4

1. Hazard and Risk Characterization ........................................................................... 4

2. Food Tolerances .......................................................................................................... 4

3. Human Incidents......................................................................................................... 5

4. Deficiencies .................................................................................................................. 5

B. ENVIRONMENTAL ASSESSMENT .......................................................................... 6

1. Environmental Fate, Exposure, and Risk ................................................................ 6

2. Ecological Incidents .................................................................................................... 6

3. Endangered Species Assessment ............................................................................... 7

C. ENDOCRINE DISRUPTOR SCREENING PROGRAM .......................................... 8

III. PROPOSED INTERIM REGISTRATION REVIEW DECISION ............................. 9

IV. NEXT STEPS AND TIMELINE ................................................................................... 10

Appendix A: Quinclorac Label Table ...................................................................................... 11

 
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I. INTRODUCTION 

 

This document is the Environmental Protection Agency’s (EPA or the Agency) Proposed 

Interim Registration Review Decision for quinclorac (PC code 128974) and is being issued 

pursuant to 40 CFR sections 155.56 and 155.58. A registration review decision is the Agency's 

determination whether a pesticide meets, or does not meet, the standard for registration in the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it 

determines it to be appropriate, an interim registration review decision before completing a 

registration review. Among other things, the interim registration review decision may: 1) require 

new risk mitigation measures; 2) impose interim risk mitigation measures; 3) identify data or 

information required to complete the review; and 4) include schedules for submitting the 

required data, conducting the new risk assessment and completing the registration review. For 

further information on quinclorac, additional documents can be found in EPA’s public docket 

(EPA-HQ-OPP-2007-1135) at www.regulations.gov. 

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

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

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

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

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

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

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

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

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

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

is provided as www.epa.gov/oppsrrd1/registration_review/. 

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

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

continues to meet the FIFRA standard for registration. 

The first pesticide product containing quinclorac was registered in 1992. Quinclorac is a 

systemic herbicide registered for use in controlling certain broadleaf and grass weeds. Currently 

registered uses of quinclorac include turf grasses, sorghum, wheat, rangeland/pasture, rights-ofway/fencerow/hedgerow, grass grown for seed, fallow land, grass forage/fodder/hay, rice, 

rhubarb, and certain low growing berries. Because quinclorac was not registered until 1992, it 

was not subject to reregistration and therefore no Reregistration Eligibility Decision document 

(RED) for this chemical was completed. 

Pursuant to 40 CFR §155.50, the Agency formally initiated registration review for 

quinclorac (case 7222). The following highlights significant events that have occurred during 

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

1135, accessed at www.regulations.gov): 
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 December 19, 2007 –The Quinclorac Summary Document was published for a 60-day 

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

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

 June 12, 2008– Final Work Plan (FWP) for quinclorac was posted. Two comments were 

received but they did not modify the PWP. 

 January 2010 – Generic Data Call-In Notice (GDCI) for quinclorac was issued. 

 June 26, 2013 - The Agency published the human health risk assessment Quinclorac: 

Risk Assessment In Support of Registration Review and for New Proposed Use on 

Rhubarb and Berry, low growing, except Strawberry, Subgroup 13-07H and the 

ecological risk assessment Registration Review - Ecological Risk Assessment for 

Quinclorac for a 60-day public comment period. No comments were received during the 

comment period. 

 September 2014 – The Agency is now publishing the Quinclorac Proposed Interim 

Registration Review Decision for a 60-day public comment period.

II. SCIENTIFIC ASSESSMENTS 

A. HUMAN HEALTH RISK ASSESSMENT 

A summary of the Agency’s human health risk assessment is presented below. The 

Agency used the HED scoping document, its supporting documents, and the most updated 

Agency science policies and risk assessment methodologies to prepare a quantitative risk 

assessment in support of the registration review of quinclorac. The most recent previous human 

health risk assessment was conducted in November, 2012. For a detailed discussion, see the 

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

Use on Rhubarb and Berry, low growing, except Strawberry, Subgroup 13-07H., published in the 

public docket EPA-HQ-OPP-2007-1135, which can be accessed on http://www.regulations.gov/. 

1. Hazard and Risk Characterization 

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. All acute and chronic 

dietary risk estimates for quinclorac are below EPA’s level of concern. The exposure scenarios 

for residential and occupational exposure yield risk estimates that do not exceed EPA’s level of 

concern. 

2. Food Tolerances 

US pesticide tolerances for quinclorac are listed under 40 CFR 180.463. 
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As a result of registration review, EPA recommends that the tolerance on Grain, aspirated 

fractions be revoked. 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. 

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. The existing tolerances for poultry meat byproducts and hog fat and meat byproducts 

are too high. 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, 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. 

A complete summary of the proposed tolerance changes for quinclorac in registration 

review appear on Page 10 of the Quinclorac Human Health Risk Assessment, document EPAHQ-OPP-2007-1135-0017 at regulations.gov. 

3. Human Incidents 

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

A 2007 human health review by EPA for quinclorac identified two incidents in the Main and 

Aggregate Incident Data System (IDS) from 1999 to 2007; five quinclorac cases in the Poison 

Control Centers (PCC) database from 1993 to 2005; and no incidents in the National Institute of 

Occupational Safety and Health Sentinel Event Notification System for Occupational Risks 

(NIOSH SENSOR) data from 1998 to 2003. An incident review conducted in 2012 found an 

increase in the number of incidents since the previous incident review performed in 2007, a 

change most likely due to the removal in 2007 of a self-imposed restriction by the registrant that 

all quinclorac products used to treat residential turf could be applied only by a certified 

applicator. The vast majority of these incidents were of low severity. 

4. Deficiencies 

The following deficiencies were noted in the Human Health Risk Assessment: 

 The risk assessment indicated that the use of quinclorac on rice and cranberry fields 

requires additional residue data to be provide unless all labels prohibit use of treated 

water from rice and cranberry fields in aquaculture. 

o Since the publication of the risk assessment, EPA has verified that all quinclorac 

product labels contain the following restriction: “Do not use treated rice fields for 

aquaculture of edible fish and crustaceans (crayfish).” No additional data or 

changes are needed to address this concern. 

 A new analytical standard for the quinclorac DMA salt for the EPA National Pesticide 

Standards Repository. 
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B. ENVIRONMENTAL ASSESSMENT

During registration review, the Agency identified risk concerns for terrestrial plants. For 

detailed discussions of all aspects of the environmental risk assessment, see the Registration 

Review - Ecological Risk Assessment for Quinclorac, published on June 26, 2013 in the public 

docket (EPA-HQ-OPP-2007-1135) which can be accessed on http://www.regulations.gov/. A 

summary of the Agency’s environmental risk assessment for quinclorac is presented below. 

1. Environmental Fate, Exposure, and Risk 

The ecological risk assessment concluded that quinclorac posed a risk concern for direct 

effects to non-target listed and non-listed terrestrial plant species across most uses and use sites 

for quinclorac. The LOC was also exceeded for listed aquatic vascular plants from use of 

quinclorac on rice. The potential for risk to terrestrial plants indicated by LOC exceedances is 

supported by documented plant incidents involving the use of quinclorac. In particular, 

ecological effects data indicate that tomatoes are especially sensitive to quinclorac and incidents 

involving tomatoes associated with the application of quinclorac to rice have been reported in 

northeast Arkansas. 

Regardless of the use or application rate, a risk concern was not identified for direct 

effects to birds, reptiles, and terrestrial-phase amphibians; mammals; terrestrial invertebrates; 

freshwater fish and aquatic-phase amphibians; estuarine/marine fish; freshwater invertebrates; 

estuarine/marine invertebrates; and aquatic non-vascular plants. 

2. Ecological Incidents 

A review of the Ecological Incident Information System (EIIS) maintained by the 

Agency’s Office of Pesticide Programs (OPP) on August 10, 2012 indicated two reported 

ecological incidents associated with the use of quinclorac) associated with the use of quinclorac. 

Both incidents involved plant damage to tomatoes in Arkansas from drift exposure as a result of 

aerial applications to rice. These incidents ultimately resulted in tomato growers of Poinsett 

County, Arkansas, filing a petition for cancellation of quinclorac. A study by the University of 

Arkansas in response to complaints by tomato growers was initiated in 1999. The study reported 

detectable amounts of quinclorac in ambient air over tomato fields, chemical residues in tomato 

plant tissues, and documented varying degrees of abnormal growth symptoms consistent with 

those known to be caused by quinclorac, but concluded that it was not possible to determine the 

specific sources of the airborne quinclorac because on many days when quinclorac was detected 

in air samples, there was no reported application within 5 miles of the experimental site. 

Additional incidents are reported to the Agency in aggregated form. Pesticide registrants 

report certain types of incidents to the Agency as aggregate counts of incidents occurring per 

product per quarter. For quinclorac, registrants have reported no fish and wildlife incidents, 481 

minor plant incidents, and no other non-target incidents as of August 10, 2012. The total number 

of actual incidents associated with the use of quinclorac may be higher than what is reported to 

the Agency. Incidents may go unreported since effects may not be immediately apparent and/or 

readily attributed to the use of a chemical. 
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No incidents involving birds were reported in the Avian Monitoring Information System 

(AIMS), which is maintained by the American Bird Conservatory, as of August 10, 2012.

3. Endangered Species Assessment 

In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the 

National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department 

of Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks 

to listed species from pesticides. The Interim Approaches were developed jointly by the 

agencies in response to the National Academy of Sciences’ (NAS) recommendations and reflect 

a common approach to risk assessment shared by the agencies as a way of addressing scientific 

differences between the EPA and the Services. The NAS report outlines recommendations on 

specific scientific and technical issues related to the development of pesticide risk assessments 

that EPA and the Services must conduct in connection with their obligations under the 

Endangered Species Act (ESA) and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on 

November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the 

December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues 

Research and Evaluation Group (SFIREG) meetings, and held a stakeholder workshop in April 

2014, allowing additional opportunities for stakeholders to comment on the Interim Approaches. 

As part of a phased, iterative process for developing the Interim Approaches, the agencies will 

also consider public comments on the Interim Approaches in connection with the development of 

upcoming Registration Review decisions. The details of the joint Interim Approaches are 

contained in the white paper “Interim Approaches for National-Level Pesticide Endangered 

Species Act Assessments Based on the Recommendations of the National Academy of Sciences 

April 2013 Report,” dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the ecological risk assessment supporting this Proposed Interim 

Registration Review Decision for quinclorac does not contain a complete ESA analysis that 

includes effects determinations for specific listed species or designated critical habitat. Of 1456 

listed species that may be affected by the use of quinclorac as identified in the 2013 ecological 

risk assessment, a “no effect” determination for direct and indirect effects can be made for 87 

species based on a lack of geographical overlap between the species and quinclorac uses. A 

preliminary assessment has, on a coarse biological and geographical data set, identified potential 

concerns for effects on individuals of the remaining 1369 species. It is possible that additional 

information and further analysis will lead to species-specific determinations of no effect; may 

effect, not likely to adversely affect; or may effect, likely to adversely affect. 

Future assessment work will allow EPA to focus its future evaluations on the types of 

species where the potential for effects exists once the scientific methods being developed by the 

agencies have been fully vetted. Once the agencies have fully developed and implemented the 

scientific methods necessary to complete risk assessments for endangered and threatened (listed) 
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species and their designated critical habitats, these methods will be applied to subsequent 

analyses for quinclorac as part of completing this registration review. 

C. ENDOCRINE DISRUPTOR SCREENING PROGRAM 

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

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

subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, 

developmental, reproductive, and general or systemic toxicity. These studies include endpoints 

which may be susceptible to endocrine influence, including effects on endocrine target organ 

histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, 

reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates 

acute tests and chronic studies that assess growth, developmental and reproductive effects in 

different taxonomic groups. As part of its most recent registration decision for quinclorac, EPA 

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

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

quinclorac is subject to the endocrine screening part of the Endocrine Disruptor Screening 

Program (EDSP). 

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

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

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

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

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

the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or 

T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the 

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

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

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

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

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

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of 

chemicals, including quinclorac, identified for EDSP screening was published on June 14, 20131

and includes some pesticides scheduled for Registration Review and chemicals found in water. 

Neither of these lists should be construed as a list of known or likely endocrine disruptors. For 

further information on the status of the EDSP, the policies and procedures, the lists of chemicals, 

future lists, the test guidelines and the Tier 1 screening battery, please visit our website.2

 

1

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

chemicals. 

2 http://www.epa.gov/endo/
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In the interim, EPA is making no human health or environmental safety findings 

associated with the EDSP screening of quinclorac. Before completing this registration review, 

the Agency will make an EDSP FFDCA section 408(p) determination. 

 

III. PROPOSED INTERIM REGISTRATION REVIEW DECISION 

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

proposed interim registration review decision document. EPA’s proposed Interim Registration 

Review Decision for quinclorac is that (1) no additional data, other than analytical standards for 

the quinclorac DMA salt, are required at this time; and (2) labeling changes are needed at this 

time to mitigate risks to terrestrial plants. EPA is requesting the registrant submit updated 

analytical standard for the quinclorac DMA salt to the EPA National Pesticide Standards 

Repository. A completed effects determination under the Endangered Species Act (ESA) for 

quinclorac is not included in this proposed interim decision. With the exception of 87 species 

that do not overlap in geographic location with quinclorac use, it has not yet been determined 

whether quinclorac poses a risk from direct or indirect adverse effects to non-listed and listed 

species or to adversely modify any designated critical habitat for such species. 

On the basis of the findings of the 2012 human health risk assessment for quinclorac 

resulting in no risks above the Agency’s level of concern, no human health mitigation is being 

undertaken for quinclorac at this time by the Agency. 

EPA plans to propose making various revisions to the current quinclorac tolerances. The 

tolerance on Grain, aspirated fractions, will be revoked. The existing tolerances for poultry meat 

byproducts and hog fat and meat byproducts will be lowered to 0.05 ppm. In addition, the 

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

information on EPA’s proposed tolerance changes for quinclorac can be found on Page 10 of the 

Quinclorac Human Health Risk Assessment, document EPA-HQ-OPP-2007-1135-0017 at 

regulations.gov. 

As discussed in the Environmental Fate, Exposure, and Risk section of this document, 

quinclorac has been determined to pose a potential risk concern for non-target listed and nonlisted terrestrial plant species. To address this concern, the Agency is proposing various label 

changes for quinclorac registrations. These label amendments are intended to reduce spray drift 

from the application of quinclorac products. EPA’s intention is to revise current quinclorac label 

language to establish a baseline level of protection against spray drift that is consistent across all 

quinclorac products. All registrants are encouraged to surpass this baseline level of protection 

and submit revisions to quinclorac label language that will reduce the risk of spray drift as much 

as possible given efficacy considerations. After discussion with all of the companies that are 

technical registrants for quinclorac, the Agency is proposing the following label restrictions: all 

quinclorac labels shall limit (1) product droplet size during applications to medium or coarser 

droplet size according to the American Society of Agricultural and Biological Engineering 

(ASABE) standard; (2) application release height to no greater than 30 inches from the ground 

limit for ground applications and no greater than 10 feet from the ground or the top of the crop 

for aerial applications, unless a higher application height is required for reasons of pilot safety; 
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(3) wind speed during applications to be no greater than 10 mph; and (4) a product’s maximum 

single application rate to be no greater than 0.75 lb ai/A. Implementing these label changes will 

not entirely eliminate risks from quinclorac to all non-target terrestrial plants, but doing so will 

nevertheless reduce spray drift during quinclorac applications, thus establishing a higher level of 

environmental protection than that afforded by current labels by reducing the number of plants 

that might be exposed 

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

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

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

quinclorac will depend upon both the result of an ESA Section 7 consultation with the Services, 

and an EDSP FFDCA section 408(p) determination. 

IV. NEXT STEPS AND TIMELINE

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

proposed interim registration review decision document, and placing it in the quinclorac 

registration review docket (EPA-HQ-OPP-2007-1135) for public comment for 60 days. A 

Federal Register Notice will announce the availability of this proposed interim registration 

review decision for quinclorac and initiate a 60-day comment period. Comments are especially 

welcomed by the Agency on the subject of proposed tolerance updates and the label language 

amendments proposed by EPA to mitigate risks to terrestrial plants from use of quinclorac. If 

there are no significant comments or additional information submitted to the docket during the 

comment period that leads the Agency to change its proposed decision, EPA will issue an interim 

registration review decision for quinclorac (case 7222). 

Once the Interim Registration Review Decision is issued, registrants will need to submit 

amended labels that include the label changes summarized in Appendix A to the Agency for 

approval within 60 days. 

 
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Appendix A:		Quinclorac Label Table	 	

Summary of Proposed Labeling Changes for Quinclorac End-Use Products 

 Application 

Parameter Proposed Amended Labeling Language for Quinclorac Use Products 

Placement on 

Label 

Maximum Single 

Application Rate 

The maximum single application rate for quinclorac is 0.75 lbs a.i./acre. All 

labeled rates must be updated to reflect this maximum rate. 

Directions for 

Use 

Droplet Size “Apply as a medium or coarser spray (ASABE standard 572).” 

Directions for 

Use 

Release Height 

For ground applications: 

“Do not release spray at a height greater than 30 inches above the ground.” 

For aerial applications: 

“Do not release spray at a height greater than 10 feet above the ground or crop 

canopy.” 

Directions for 

Use 

Wind Speed “Do not apply when wind speeds are greater than 10 mph at the application 

site.” 

Directions for 

Use