Docket Number EPA-HQ-OPP-2014-0167
www.regulations.gov

Clopyralid
Interim Registration Review Decision
Case Number 7212
December 2020
Approved by:

Elissa Reaves, Ph.D.
Acting Director
Pesticide Re-evaluation Division
Date:
12-16-2020

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Table of Contents
I.	INTRODUCTION	3
A.	Updates since the Proposed Interim Decision was Issued	4
B.	Summary of Public Comments on the Proposed Interim Decision	5
II.	USE AND USAGE	6
III.	SCIENTIFIC ASSESSMENTS	7
A.	Human Health Risks	7
Risk Summary and Characterization	7
Human Incidents and Epidemiology	9
Tolerances	9
Human Health Data Needs	9
B.	Ecological Risks	10
Risk Summary and Characterization	10
Ecological Incidents	12
Ecological and Environmental Fate Data Needs	13
C.	Benefits Assessment	13
IV.	INTERIM REGISTRATION REVIEW DECISION	14
A. Risk Mitigation and Regulatory Rationale	14
1.	Restricted Entry Interval	14
2.	Updated Gloves Statement	14
3.	Measures to Address Potential Compost Contamination	15
a.	Residential Turf Prohibition	15
b.	Compost Prohibition, Notification, and Recordkeeping	15
c.	Education Materials and Stewardship Plans	18
d.	Revision of Compost Pictogram	19
4.	Spray Drift Management	21
5.	Non-target Organism Advisory	22
6.	Surface and Ground Water Advisories	23
7.	Herbicide Resistance Management	24
8.	T olerance Actions	24
9.	Interim Registration Review Decision	25
10.	Data Requirements	25
V.	NEXT STEPS AND TIMELINE	26
A.	Interim Registration Review Decision	26
B.	Implementation of Mitigation Measures	26
Appendix A: Summary of Actions for Clopyralid	27
Appendix B: Labeling Changes for Clopyralid Products	28
Appendix C: EPA Responses to Comments	34
Appendix E: Endangered Species Assessment	57
Appendix F: Endocrine Disruptor Screening Program	59
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I. INTRODUCTION
This document is the Environmental Protection Agency's (EPA or the Agency) Interim
Registration Review Decision (ID) for clopyralid. This case includes the clopyralid parent (PC
code 117403), the potassium salt (PC Code 117423), monoethanolamine salt (PC Code 117401),
dimethylamine salt (PC Code 11710) and triethanolamine salt (PC Code 117404) and is being
issued pursuant to 40 CFR ง 155.56 and ง155.58. A registration review decision is the Agency's
determination whether a pesticide continues to meet, 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 determine that new risk mitigation measures are necessary, lay out interim risk mitigation
measures, identify data or information required to complete the review, and include schedules for
submitting the required data, conducting the new risk assessment and completing the registration
review. Additional information on clopyralid, can be found in EPA's public docket (EPA-HQ-
OPP-2014-0167) at www.regutation s. gov.
FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandates the
continuous review of existing pesticides. All pesticides distributed or sold in the United States
must be registered by 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 at http://www.epa.gov/pesticide-reevaluation. In 2006, the Agency implemented the
registration review program pursuant to FIFRA ง 3(g) and will review each registered pesticide
every 15 years to determine whether it continues to meet the FIFRA standard for registration.
EPA is issuing an ID for clopyralid so that it can (1) move forward with aspects of the
registration review that are complete and (2) implement interim risk mitigation (see Appendices
A and B). The Agency is currently working with the U.S. Fish and Wildlife Service and the
National Marine Fisheries Service (collectively referred to as, "the Services") to improve the
consultation process for conducting national threatened and endangered (listed) species
assessments for pesticides in accordance with the Endangered Species Act (ESA) ง 7. Therefore,
although EPA has not yet fully evaluated risks to federally-listed species, the Agency will
complete its listed species assessment and any necessary consultation with the Services for
clopyralid prior to completing the clopyralid registration review. Likewise, the Agency will
complete endocrine screening for clopyralid, pursuant to the Federal Food, Drug, and Cosmetic
Act (FFDCA) ง 408(p), before completing registration review. See Appendices E and F,
respectively, for additional information on the listed species assessment and the endocrine
screening for the clopyralid registration review.
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Clopyralid is a pyridine carboxylic acid herbicide with selective toxicity to broadleaf weeds.
Products containing clopyralid are currently registered for use to control weeds on a variety of
agricultural crops (including fruits, vegetables, and cereal grains), as well as non-residential turf
(including golf courses and athletic/recreational fields), ornamentals, rights of ways, pasture, and
rangeland. Use of clopyralid on residential turf (e.g., home lawns) was voluntarily cancelled by
the registrant in 20021. Because it was registered after November 1984, clopyralid was not
subject to reregi strati on under FIFRA ง 4(a).
This document is organized in five sections: the Introduction, which includes this summary and a
summary of public comments and EPA's responses; Use and Usage, which describes how and
why clopyralid is used and summarizes data on its use; Scientific Assessments, which
summarizes EPA's risk and benefits assessments, updates or revisions to previous risk
assessments, and provides broader context with a discussion of risk characterization; the Interim
Registration Review Decision, which describes the mitigation measures to address risks of
concern and the regulatory rationale for EPA's ID; and, lastly, the Next Steps and Timeline for
completion of this registration review.
A. Updates since the Proposed Interim Decision was Issued
In this ID there are several updates to the label language proposed in the March 2020 Proposed
Interim Decision (PID). The updates include changes to label language aimed at mitigating the
potential for compost contamination. In the PID, the Agency proposed the following measures
to address compost contamination concerns:
•	Expansion of the current residential lawn/turfs prohibition to school grounds.
•	A prohibition on treated materials or manure from animals that have grazed in treated
areas being used for compost, mulch, or mushroom spawn.
•	A requirement for applicators to notify property owners/operators, and/or customers of
the compost prohibition and keep a record of this notification. Applications to public
lands were proposed to be excluded from this requirement.
•	A requirement for a 3-day clean out period before livestock that grazed on treated
materials could be moved from the treated property.
•	A requirement for labels to include a pictogram showing ways to prevent compost
contamination.
•	A requirement for educational materials to be generated and a stewardship plan to inform
property owners/operators, applicators, and others along the compost supply chain on the
potential for clopyralid to contaminate compost and ways to prevent residues from
entering the compost stream.
EPA has determined that it is not necessary to prohibit use of clopyralid on school grounds since
this is an institutional use and not a residential use. In public comments, stakeholders note that
institutional turf sites, such as school lawns, are generally managed by lawn care operators and
turf clippings at these sites are frequently left onsite to decompose in order to improve soil
1 EPA published FIFRA 6(f) notices for three clopyralid products containing directions for use on residential turf
including 62719-80 (67 FR 55241, 8/28/2002), 62719-81 and 62719-84 (67 FR 63424, 10/11/2002). A letter from
EPA to the registrant on November 26, 2002 confirmed the deletion of residential turf from these products.
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nutrition. EPA is also changing the proposed compost restriction. The PID proposed language
instructing users not to use treated plant materials for compost, mulch, or mushroom spawn. The
Agency is revising the compost restriction to note that users may not sell or transport treated
plant materials or manure from animals that have grazed on treated forage off-site for compost
distribution or for use as animal bedding/feed for 18 months after application. These changes
will allow for more flexibility for applicators and landowners and allow users to recycle/dispose
treated materials on the treated property.
The Agency has also changed the compost notification and recordkeeping requirement. The
language proposed in the PID would have required all applicators to notify property
owners/operators about the compost restrictions for every use site. This ID updates that
notification requirement to only be required for applications to pasture and turf sites. EPA is
focusing the notification and recordkeeping requirement on pasture and turf sites, as they are the
use sites mostly likely to significantly contribute plant materials into the compost stream. In the
PID, EPA exempted applications to public lands from the notification requirement. In this ID,
EPA has decided to also exempt applications made by property owners/operators on their own
property. This additional exemption is being made because property owners/operators treating
their own property should already be aware of the label directions. Limiting the scope of the
notification and recordkeeping requirement will reduce the burden for applicators using
clopyralid in sites where materials are not typically recycled into compost, while also addressing
compost concerns in the use sites where treated plant materials may be recycled.
EPA is also making changes to the proposed compost pictogram to improve clarity, and to
provide information on ways treated materials can be used.
B. Summary of Public Comments on the Proposed Interim Decision
The comment period for the clopyralid PID opened on May 5, 2020 for a 60-day comment
period set to close July 6, 2020. Due to various extension requests received, the Agency later
extended the public comment period for another 30 days, until August 5, 2020. A total of 557
comments were received during the comment period. Of these, 489 comments were from mass
mail campaigns concerned with the persistence of clopyralid and potential residues in compost.
There were also 33 other individual substantive comments that addressed the benefits, risk
mitigation, and the regulatory rationale.
Comments on the benefits of clopyralid use in various settings were submitted by United States
Department of Agriculture (USDA), IR-4 project, Agricultural Retailers Association, Georgia
Agribusiness Council, Co-Alliance, Target Specialty Products, National Cattlemen's Beef
Association, Responsible Industry for Sound Environment, CropLife America, various sugar
beet organizations, and various turfgrass organizations and companies. Comments on the
proposed compost restrictions were received from USD A, Corteva Agriscience (Corteva),
Oregon Department of Agriculture (ODA) and Washington State Department of Agriculture
(WSDA), US Composting Council (USCC) plus many concerned citizens supporting USCC
suggestions, National Agricultural Aviation Association (NAAA), various composting
companies, various agricultural organizations, various turfgrass and landscaping organizations,
and various livestock organizations. Comments on spray drift labeling were received from
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USD A and NAAA. Suggestions primarily from USD A, ODA and WSA, Corteva, NAAA and
USCC resulted in changes to the proposed compost restrictions (see section IV). Substantive
comments, comments of a broader regulatory nature, and the Agency's responses to those
comments are summarized in Appendix C of this document. The Agency thanks all commenters
for their comments and has considered them in developing this ID.
II. USE AND USAGE
Clopyralid is used in both agricultural and non-agricultural settings. Registered agricultural use
sites include apples, asparagus, barley, beets, canola, cole crops, Christmas tree plantations,
crambe, Conservation Reserve Program (CRP) land, corn (field, pop, and sweet), cranberries,
fallow, flax, hops, mint, oats, pasture, rangeland, spinach, stone fruits, strawberries, sugar beets,
turnip, and wheat. Registered non-agricultural use sites include cemeteries, farm buildings,
fencerows, industrial sites, non-residential ornamental lawns and turf, ornamental trees, athletic
fields, golf fairways, parks, and rights-of-way. Clopyralid is formulated as emulsifiable
concentrates, soluble concentrates, granules, wettable powders, and water dispersible granules. It
is applied through aerial and ground equipment.
Available Agricultural Market Research Data2 reported recent usage of clopyralid on alfalfa,
apples, asparagus, barley, cabbage, canola, cherries, corn, dry beans, fallow, pastureland,
peaches, pecans, sorghum, spinach, strawberry, sugar beets, sweet corn, and spring and winter
wheat for a total of 1.6 million pounds active ingredient (lbs AI) applied to 20 million total acres
treated (TAT) annually from 2014-2018. The majority of clopyralid usage is from applications to
corn (65% of lbs AI applied per year) and spring and winter wheat (30% of lbs AI applied per
year)2. In terms of percent crop treated, clopyralid was widely used in spring wheat (30% crop
treated annually), sugar beets (25% crop treated annually), barley (20% crop treated annually)
and corn (15% crop treated annually) from 2014-20182. Aerial applications accounted for less
than 1% of the agricultural acres treated with clopyralid on average annually from 2014-20182.
Usage on rangeland and pasture sites totaled about 528,000 lbs AI of clopyralid applied in 20173.
Some clopyralid use sites (e.g., mint, cranberries, hops) are not surveyed for pesticide usage.
Non-agricultural data shows that most clopyralid usage is concentrated on turf sites maintained
by lawn care operators (LCOs)4. The primary duties of these LCO professionals are to maintain
turf areas through the use of fertilizers and pesticides for residential, commercial, and industrial
properties with lawns. LCOs used over a million pounds of clopyralid; it was one of the top five
herbicides used by LCOs in 20134. Since clopyralid use on residential turf sites (e.g., home
lawns) was voluntarily cancelled by the registrant in 2002, this usage is expected to be from the
other sites (e.g., commercial and industrial, such as golf courses) treated by LCOs. Golf courses
(34,000 lbs AI), roadways (9,000 lbs AI), railroads and forestry (9,000 lbs AI) had minor (i.e.,
about 1% or less of the herbicide pounds applied to the particular use site) usage4'5 of clopyralid.
2	Kynetec USA, Inc. 2019, The AgroTrak Study, Database Subset: 2014-2018.
3	Non-Agricultural Market Research Proprietary Data (NMRD). 2017. Studies conducted and sold by a consulting
and research firm. Report on Consumer Markets for Pesticides and Fertilizers. [Accessed October 2019.]
4	Kline and Company. 2014. Professional Turf and Ornamental Markets for Pesticides and Fertilizers 2013: U.S.
Market Analysis and Opportunities. [Accessed October 2019.]
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The Agency does not have data on how clopyralid is applied to non-agricultural use sites, but it
is expected that ground applications would be most likely given typical practices and the nature
of the use sites.
For additional information on the usage of clopyralid, see the document Clopyralid Use, Usage
and Benefits.
III. SCIENTIFIC ASSESSMENTS
A. Human Health Risks
A summary of the Agency's human health risk assessment is presented below. The Agency used
the most current science policies and risk assessment methodologies to prepare a risk assessment
in support of the registration review of clopyralid. For additional details on the human health
assessment for clopyralid, see the Clopyralid Draft Human Health Risk Assessment for
Registration Review of the Herbicide and the Clopyralid Response to Comments and Addendum
to the Draft Human Health Risk Assessment in Support of Registration Review, which is
available in the public docket.
Risk Summary and Characterization
Dietary Risks
The Agency dietary (food + water) risk assessment did not identify risks of concern. An acute
dietary risk assessment was not conducted due to lack of an endpoint attributable to a single
dose. Chronic dietary risk estimates were calculated and were not of concern. Children 1-2
years old were the highest-exposed population subgroup, with risk estimates equal to 26% of the
chronic population adjusted dose (cPAD); the Agency's level of concern for dietary risk is 100%
of the PAD. Therefore, there are no dietary risks of concern for clopyralid.
Residential Risks
Use of clopyralid on residential turf (e.g., home lawns) was voluntarily cancelled by the
registrant in 2002. Therefore, a residential handler assessment was not conducted. In addition,
current labels specify Personal protective equipment (PPE); since current labels specify clothing
and personal protective equipment, the Agency has assumed that clopyralid products are not
intended for homeowner use. Clopyralid is registered for use on commercial turf, such as golf
courses, so a residential post-application assessment was conducted. The residential post-
application risk estimate for children 1-2 years old was not of concern (margin of exposure
[MOE]=10,000, where numbers below 100 are potentially of concern).
Aggregate Risks
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Aggregate risks reflect combined dietary (food and drinking water) and residential exposures.
An acute aggregate risk assessment was not conducted because an appropriate endpoint for a
single exposure was not identified. A short-term aggregate risk assessment was conducted and
the resulting margins of exposure (MOEs) were not of concern (MOE= 1,600, where numbers
below 100 are of concern). Chronic aggregate risk estimates are equal to chronic dietary risk
estimates and are not of concern.
Non-occupational Spray Drift
Non-occupational spray drift risk estimates reflect exposures for children and adults who have
contact with turf where residues are assumed to be deposited via spray drift. A quantitative
spray drift assessment for clopyralid was not required because the post-application turf
assessment is considered protective of potential exposure from spray drift. Residential turf post-
application risk estimates are not of concern.
Cumulative Risks
EPA has not made a common mechanism of toxicity to humans finding as to clopyralid and any
other substance and it does not appear to produce a toxic metabolite produced by other
substances. Therefore, EPA has not assumed that clopyralid has a common mechanism of
toxicity with other substances for registration review.
Occupational Handler Risks
Occupational handlers are individuals who are involved in the pesticide application process
(including mixers, loaders, and applicators). All handlers are assumed to wear baseline attire,
which consists of long-sleeved shirt, long pants, and shoes plus socks, except for aerial
applicators who are assumed to be in enclosed cabs. No dermal assessment was completed since
no dermal hazard was identified in the toxicity database. Short- and intermediate-term inhalation
risks for occupational handlers are not of concern. Corrections to the assessment of occupational
hander risks are presented in Clopyralid Response to Comments and Addendum to the Draft
Human Health Risk Assessment in Support of Registration Review, which is available in the
docket. The corrected occupational handler MOEs range from 540 to 1 billion and do not alter
the overall risk conclusions.
Occupational Post-Application Risks
Post-application exposures occur when individuals are present in an environment that has been
treated with clopyralid and include activities such as scouting for pests or hand-harvesting.
Dermal post-application exposure was not evaluated, due to the lack of toxicity observed in the
database from the dermal route.
Clopyralid acid is a severe eye irritant as a result, a restricted entry interval (REI) of 48 hours is
necessary for uses that fall under the Worker Protection Standard (WPS). Even if the clopyralid
end use product is not formulated with clopyralid acid but with one of clopyralid's multiple salt
forms, when the salt form product is diluted with water in a tank mix, the salt converts to
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clopyralid acid. The risk assessment indicates that a restricted entry interval (REI) of 48 hours is
protective for uses that fall under the Worker Protection Standard (WPS).
A quantitative occupational post-application inhalation exposure assessment was not performed.
Handler exposure from outdoor application is likely to result in higher exposure than post-
application exposure. Since occupational inhalation handler exposure is not of concern, it is
expected that occupational post-application inhalation exposure is also not a risk of concern.
Human Incidents and Epidemiology
The previous clopyralid human incidents search was conducted in 2013 for the scoping
document and an updated search for human incidents was conducted on August 21, 2018 for new
incidents since the 2013 search. Both the Incident Data System (IDS) and the National Institute
for Occupational Safety and Health (NIOSH) Sentinel Event Notification System for
Occupational Risk (SENSOR)-Pesticides databases were searched.
In the updated analysis (2013-2018), eleven clopyralid incidents were reported in Main IDS
involving multiple active ingredients: one incident was classified as major severity, eight were
classified as moderate severity, and two were classified as minor severity. However, these
incidents involved multiple pesticides tank-mixed together and it is difficult to determine which
pesticide the health effects should be attributed. There were 44 clopyralid incidents reported in
Aggregate IDS, these incidents were classified as minor severity.
As noted in 2013, SENSOR-Pesticides data from 1998-2009 identified 45 cases involving
clopyralid, three of which reported a single active ingredient and were low severity occupational
cases that reported respiratory symptoms. Based on updated information from SENSOR-
Pesticides data from 2010-2014, ten additional cases were identified, all of which included
multiple active ingredients and were considered of low severity.
The Agency will continue to monitor the incident information. Additional analyses will be
conducted if ongoing human incident monitoring indicates a concern.
Tolerances
Tolerances for clopyralid are established under 40 CFR ง180.431. No revision to the established
tolerances or the residue definition is necessary. There are no tolerance harmonization issues for
clopyralid.
Human Health Data Needs
The Agency does not anticipate any further data needs for the registration review of clopyralid at
this time.
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B. Ecological Risks
A summary of the Agency's ecological risk assessment is presented below. The Agency used the
most current science policies and risk assessment methodologies to prepare a risk assessment in
support of the registration review of clopyralid. For additional details on the ecological
assessment for clopyralid, see the Clopyralid: Draft Ecological Risk Assessment for Registration
Review, which is available in the public docket.
EPA is currently working with its federal partners and other stakeholders to implement to
implement a Revised Method2 for assessing potential risk to listed species and their designated
critical habitats. Once the scientific methods necessary to complete risk assessments for listed
species and their designated critical habitats are finalized, the Agency will complete its
endangered species assessment for clopyralid. See Appendix E for more details. As such,
potential risks for non-listed species only are described below.
Risk Summary and Characterization
Terrestrial Risks
Birds. Reptiles and Terrestrial-Phase Amphibians
There are no acute or chronic risks of concern for birds, reptiles, and terrestrial-phase
amphibians. Acute risk quotients (RQs) range from <0.01 to 0.18 and are below the Agency's
acute level of concern (LOC) of 0.5. Chronic RQs range from <0.01 to 0.12 and are below the
Agency's chronic risk LOC of 1.0.
Mammals
There are no acute risks of concern identified for mammals (RQs < 0.01). The acute oral toxicity
endpoint is non-definitive (the amount of substance required to kill 50% of the test population
was not determined; the LDso>5,000 mg Al/kilogram body weight) and is at least 20 times
higher than the highest estimated environmental concentration (EEC).
Chronic dietary-based RQs did not exceed the LOC (RQs < 0.24). Chronic dose-based RQs
ranged from <0.01 to 2.1 which exceeded the chronic LOC of 1 for applications on ornamentals,
grass, turf, mint, peppermint, spearmint, stone fruits, brassica vegetables, apples, asparagus,
corn, sugar beets, fallow land, conifer and deciduous trees, hops, and strawberries. Chronic
adverse effects observed in the 2-generation rat reproduction study included a 3 to 12% reduction
in body weights for parents and offspring. Mean Kenaga values (or mean residue concentrations
on various food items) were used to further characterize the chronic dose-based RQs. Using the
mean Kenaga values, there are no LOC exceedances for any use (maximum RQ=0.74).
2 https://www.regulations.gov/document?D=EPA-HO-OPP-2019-0185-0Q84
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Spray drift residue concentrations within 5 feet of the treated field result in RQs that fall below
the LOC. None of the EECs reached the lowest observable adverse effect concentration
(LOAEC) of 1500 mg/kg diet.
Terrestrial Invertebrates (honey bees)
A Tier 1 risk assessment was conducted to assess risk to bees, which are surrogates for terrestrial
invertebrates, using acute contact and oral exposure data for adult honey bees. The Agency
found that RQs did not exceed the LOC of 0.4 for adult bees from acute contact exposure (acute
contact RQ < 0.01) or from acute oral exposure (acute oral RQ < 0.16). However, at the time that
the ecological risk assessment was conducted, there were no available data to determine chronic
toxicity to adult bees, and no data to assess both acute and chronic toxicity to larval bees.
Since the issuance of the ecological risk assessment for clopyralid, two chronic bee studies (a
repeat dose larval toxicity honey bee study5 and a chronic adult honey bee oral toxicity study6)
have been submitted and reviewed, allowing the Agency to assess chronic risks to adult honey
bees and acute and chronic dietary risks to larval bees. New honey bee RQs are presented in
Table 1. EPA's review of the new bee studies found no exceedances of the acute or chronic
dietary risk level of concern for both adult and larval honey bees.
Table 1. RQs for honey bees, updated since the 2018 ecological risk assessment (bolded values
represent new information) LOC = 0.4.
Exposure Route
Adult honey bees
Larval honey bees
Acute Contact
0.01
NA
Acute Dietary
0.16
0.26
Chronic Dietary
0.22
0.26
Based on the results of the Tier 1 pollinator studies for which there were no LOC exceedances,
no additional pollinator data are needed at this time.
Terrestrial Plants
As expected from an herbicide, there are risks of concern for terrestrial plants. Terrestrial plant
RQs exceeded the LOC and ranged from <0.1 to 13.1 from ground spray (where RQs above 1
exceed the LOC). RQs for aerial application also exceeded the LOC and ranged from <0.1 to
49.3. The highest terrestrial plant RQs are from spray drift exposure, and risk to non-target plants
extends over 1,000 feet from the edge of the treated field. Lowering the boom height for ground
applications and increasing droplet size reduced the distance from the edge of the field where
residues reach below the LOC. At the highest ground application rate with a low boom and a fine
to medium droplet size, risk to non-target plants extends up to 810 feet from the edge of the field.
5	Leonard, J. and Moore, S. (2017): Clopyralid: A repeated-exposure laboratory toxicity study in larvae, pupae and
emergent adults of the honeybee Apis mellifera Linnaeus. MRID 50695902.
6	Leonard, J. and Moore, S. (2017): Clopyralid: A laboratory study to determine the chronic oral toxicity to the adult
worker honeybee Apis mellifera L. MRID 50695903.
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Of the 333 major and 329 minor terrestrial plant incidents involving clopyralid reported to the
Agency, many of incidents were attributed to spray drift onto adjacent crops.
Terrestrial plant incidents resulting from exposure to clopyralid via residues in compost
demonstrate an additional concern. There were 12 compost incidents reported for clopyralid in
the incidents database, and multiple incidents impacted compost facilities. Reported compost
incidents are likely due to how persistent the clopyralid is and how phytotoxic it can be at low
concentrations. The common routes of exposure to composting facilities and compost in general
is through grass clippings from lawns treated with clopyralid, hay from treated pasture, and
manure from livestock that have grazed on clopyralid-treated lands. Once a composting facility
is contaminated with clopyralid, non-target plants further downstream in the compost distribution
chain can be adversely impacted (e.g., gardens, ornamental plants).
Aquatic Risks
There are no risks of concern for freshwater or estuarine/marine fish (or the aquatic-phase
amphibians for which freshwater fish serve as surrogates), freshwater or estuarine/marine
invertebrates, or aquatic vascular and non-vascular plants. Clopyralid has been detected in
surface water and groundwater.
Ecological Incidents
A search of the Incident Data System (IDS) for clopyralid was conducted on September 7, 2018.
The search reflects all reported incidents since the first products containing clopyralid were
registered until the date of the search. IDS returned 333 incidents, all of which involved damage
to terrestrial plants. Incidents are classified according to certainty, from "highly probable" to
"unlikely." Of the incidents, 20 had a "highly probable" classification, 138 had a "probable"
classification, 170 had a "possible" classification, and two incidents were classified as "exposure
only." Many of the incidents were attributable either to direct application of a clopyralid product
to the affected crop, often corn, or to spray drift to adjacent crops. Twelve incidents with
clopyralid involved non-target plant damage due to residues in compost. Some of these events
received media attention, including compost facility contamination that occurred in Spokane,
WA multiple times between 1999 and 2003, Southern California during 2002, and Chittenden
County, VT during 2013. In November 2020, the Oregon Department of Agriculture reported
three new incidents of clopyralid contaminating compost and causing non-target plant damage
downstream; these incidents have not yet been indexed in the IDS. These specific events led to
plant damage in many gardens and other vegetated areas where the contaminated compost was
applied. See Appendix D for additional information on the reported compost incidents.
A search for aggregate incidents reported 329 minor plant incidents, 5 minor wildlife incidents
and 2 other non-target minor incidents (1996-2018). The wildlife incidents involve vertebrate
animals and the other non-target incidents involve invertebrates.
The Agency will continue to monitor the ecological incident information. Detailed analyses of
these incidents are conducted if reported information indicates concerns for risk to non-target
organisms.
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Ecological and Environmental Fate Data Needs
In support of registration review for clopyralid, a generic data call-in (GDCI-117403-1454) was
issued, requiring the submission of several environmental fate and ecotoxicity studies. All of the
requirements of GDCI-117403-1454 have been satisfied, except for guideline 850.2300 (avian
reproduction with upland gamebird). Guideline 850.6100 (environmental chemistry methods for
compost and associated independent laboratory validation) was previously noted as outstanding.
However, MRID 51074001 was submitted to fulfill guideline 850.6100 and has been classified
as supplemental; additional testing is not needed. MRID 00156001 was submitted to satisfy the
guideline 850.2300 avian reproduction requirement, however this study has not yet been
reviewed. The Agency will review MRID 00156001.
C. Benefits Assessment
Clopyralid is a pyridine herbicide that acts as a plant growth regulator by mimicking auxin,
classified as Class 4 by the Weed Science Society of America (WSSA). Clopyralid is a selective
herbicide for contact and systemic control of broadleaf weeds. Clopyralid is registered for use on
agricultural and non-agricultural sites.
Use of clopyralid provides benefits to users in both agricultural and non-agricultural settings.
Due to the selectivity of clopyralid to primarily control broadleaf or dicotyledonous weed species
through foliar exposure, clopyralid is one of the few herbicides that can be used to terminate
cover crops before corn and wheat with no expectation of residual injury. Clopyralid provides
benefits to users in pasturelands due to its excellent control of woody species, such as locust and
mesquite, that are commonly problematic in these sites. A unique benefit of pyridine herbicides,
such as clopyralid, is that they provide more selective control of mesquite species, so they can be
used as a more targeted herbicide in brush control compared to other effective mesquite controls.
This benefit allows land managers to maintain desirable shrub species in the landscape to serve
as shade and forage for grazing livestock. Clopyralid is considered safe for use on many warm
and cool season grass species common to golf course fairways and greens. Clopyralid provides
excellent control of several hard to kill broadleaf weeds in turf and on golf courses including hop
clover, white clover, red sorrel, henbit, purple deadnettle, common lespedeza, and wild
strawberry. Lawn care operators like clopyralid because of its benefit in lawns such as control of
certain broadleaf weeds, especially weed species from the genera Oxalis and Trifolium such as
creeping oxalis and white clover, respectively.
Other class 4 synthetic auxin herbicides, such as triclopyr, aminopyralid, and fluroxypyr are the
primary alternatives to clopyralid across use sites.
For additional information on the benefits and alternatives of clopyralid, see the Clopyralid Use,
Usage and Benefits document.
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IV. INTERIM REGISTRATION REVIEW DECISION
A. Risk Mitigation and Regulatory Rationale
The Agency has reviewed the risks and benefits associated with the registered uses of clopyralid
in developing this Interim Registration Review Decision. EPA has determined that there are no
dietary, residential, aggregate, occupational handler, or non-occupational spray drift risks of
concern. There is potential for occupational post-application risk because clopyralid products
can become a severe eye irritant when diluted in water. Due to the potential for eye irritation, a
48-hour REI is necessary to address post-application risks for workers entering treated areas
covered under the WPS.
The Agency identified potential risks to non-target terrestrial plants from spray drift, runoff, and
from compost contamination. There were also potential chronic risks to mammals. Mandatory
spray drift management measures are necessary to reduce risks to non-target terrestrial plants and
mammals. New compost labeling and stewardship measures are necessary to reduce the
potential for non-target plant damage from compost contamination. Herbicide resistance
management labeling and other label updates are needed to bring all labels up to current
standards.
1.	Restricted Entry Interval
Clopyralid acid is a severe eye irritant. Some clopyralid products are formulated with clopyralid
acid and some products are formulated with the various clopyralid salt forms. Even when the
clopyralid salt products are diluted with water in a tank mix, the salt is then converted to the
clopyralid acid. End-use products that contain uses that fall under the WPS need to be updated to
reflect a 48-hour REI. The Agency generally does not find major impacts with REIs of 48 hours
or less as these restrictions do not trigger the posting requirements associated with longer
periods. Some products containing clopyralid already require a 48-hour REI. The Agency
recognizes the necessary 48-hour REI may impact agricultural applicators by requiring better
scheduling of in-field tasks; however, given the short timeframe for the restriction, these impacts
will likely be minimal.
2.	Updated Gloves Statement
The gloves statements on current labels need to be updated to be consistent with guidance in
Chapter 10 of the Label Review Manual. All statements that refer to the chemical resistance
category selection chart need to be removed from clopyralid labels, as they might cause
confusion for users. Instead, the labels should list the appropriate chemical-resistant glove types
to use. This change does not fundamentally alter the personal protective equipment that workers
need to use, and therefore should minimally impact users.
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3. Measures to Address Potential Compost Contamination
a.	Residential Turf Prohibition
Use of clopyralid on residential turf (e.g., home lawns) was voluntarily cancelled by the
registrant, Dow AgroSciences (a member of the Corteva Agriscience group of companies), in
2002 on most labels (67 FR 55241, 67 FR 63424, see EPA memorandum dated November 26,
2002 to Dow AgroSciences, LLC in the docket) due to a compost contamination incident.
However, this prohibition does not appear on some end-use products. The Agency is reaffirming
the residential turf prohibition and expanding it across all labels. Residues in grass clippings
from residential lawns are commonly recycled into compost and may cause compost incidents.
Residential turf includes turf on home lawns/gardens, preschool grounds, and other residential
areas as defined in 40 CFR ง152.3. This existing residential lawn restriction does not apply to
institutional turf in athletic/recreational fields, golf courses, parks, or grass in other
institutional/commercial areas. This restriction does not pertain to non-grass ornamental plants
such as trees and shrubs that are present in residential areas.
The Agency proposed prohibiting use on school grounds in the PID but is no longer restricting
this use. Information received during the comment period indicates that institutional turf sites,
such as school lawns, are generally managed by lawn care operators and turf clippings at these
sites are frequently left onsite to decompose in order to improve soil nutrition. Based on
information received from stakeholders, EPA has decided not to restrict use on school grounds or
other institutional turf uses but instead retain the notification and recordkeeping requirement for
all turf uses.
In discussions with the Agency on February 19, 2019, Corteva Agriscience agreed that the
residential turf prohibition should be added to labels that do not currently have this restriction.
Because most clopyralid turf labels already have the residential lawn use prohibition, the Agency
does not expect this prohibition to have significant impacts on users.
b.	Compost Prohibition, Notification, and Recordkeeping
Label language to reduce the potential for clopyralid contamination of compost is necessary. As
described in EPA's ecological risk assessment, clopyralid is persistent in compost and can cause
non-target plant damage from use of composted material contaminated with clopyralid residues
as shown in past incidents. The compost prohibition7 instructs users not to sell or transport
treated plant materials or manure from animals that have grazed on treated forage off-site for
compost distribution or for use as animal bedding/feed for 18 months after application.
Increasing the awareness of property owners/operators about the potential long-term impacts of
clopyralid on their land may help prevent treated materials from entering the compost waste
stream. Pasture (where hay is collected for animal feed and bedding) and turf (where grass
clippings are collected) are the clopyralid use sites which have the highest risks of treated
materials entering the compost waste stream. The Agency considered including rangeland as part
of the compost notification and recordkeeping requirement. However, the agency has
7 See text for compost prohibition on next page.
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determined that including rangeland is not necessary. Information received from stakeholders
such as ranchers during the public comment period indicates that manure and plant materials
from rangelands are unlikely to be collected and used for offsite compost. Therefore, it is
necessary for applicators applying clopyralid to pasture and turf use sites to notify property
owners/operators in writing, that clopyralid is a persistent pesticide and that treated plant
material and manure from grazing animals exposed to clopyralid is not allowed to be sold or
transported off-site for compost distribution or for use as animal bedding/feed for 18 months
after application. Information to be communicated to the property owner/operator, in writing, by
applicators are as follows: the name of the applicator, the date of application, the area(s) treated,
the name and EPA registration number of the product applied, information on the persistence of
clopyralid, and information on any label restrictions affecting hay, manure, and plant materials
that might be recycled into compost
In addition, EPA is requiring recordkeeping where applicators applying clopyralid to pasture and
turf use sites must retain a record describing how the property owner/operator was notified of
compost restrictions. The following information is to be retained as part of the recordkeeping
requirement:
•	the name of the applicator,
•	the date of application,
•	the area(s) treated,
•	the EPA registration number of the product applied,
•	a copy of the written notification provided to the property owner/operator, and
•	the date that notification of the property owner/operator occurred.
These records should be retained by the applicator for two years. If these records are already
being kept as part of state or local requirements, duplicate records are not necessary.
Communication between the applicator and property owner/operator is important in case the
manager of the land changes over time. It is important that the property owner/operator receive
information on clopyralid applications in order to make informed decisions about the
management of treated plant materials and manure on the affected land to prevent compost
contamination. Applicators may provide notification to the landowner/applicator via email, via
mail, via paper handout, or by any other written communication method so long as notification
occurs.
Applications to public land are exempt from the notification requirement because public lands
are managed by federal, state, or local authorities or contractors hired by these authorities.
Applications by property owners/operators on their own land are also exempt from this
notification requirement as all users/applicators are already required to follow any label
requirements and it is impractical for land managers to notify themselves.
In addition to the measures noted previously, the Agency is requiring that animals that have been
fed clopyralid-treated forage must be fed forage free of clopyralid for at least 3 days before
movement to an area where manure may be collected, or sensitive crops are grown. This ensures
that manure from animals that have recently grazed on treated forage stays on site. The three-day
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period is based on open literature data which indicates the retention time for feed particles is
approximately 52 hours for cattle8, 48 hours for horses9, 45 hours for sheep, and 32 hours for
goats10. A three-day clean out period will be protective of non-treated areas with susceptible
plant species and non-treated areas where manure may be collected for compost based on this
literature.
The label language for the compost mitigation, notification, and recordkeeping requirement is as
follows:
•	"This product is persistent and may be present in treated plant materials for months to
years after application. Do not sell or transport treated plant materials or manure from
animals that have grazed on treated plant materials off-site for compost distribution or for
use as animal bedding/feed for 18 months after application."
•	For products with turf and pasture uses:
•	"The applicator must document that they have notified property owners/operators, or
customers, in writing, of the compost and animal bedding/feed prohibitions before
application of the product occurs. Applicators must keep the records of notification for
two years. This record must include date of application, the name of the applicator, the
EPA registration number of the product applied, the area(s) treated, and a copy of the
written notification provided to the property owner/operator. Notification may be made
via email, via mail, via paper handout, or by any other written communication method.
Records must be made available to State Pesticide Regulatory Official(s), and to EPA
upon request. If this information is already being retained, duplicate records are not
needed."
•	"Applications by property owners/operators on their own property are exempt from this
notification and recordkeeping requirement."
•	"Applications to public land are exempt from this notification requirement."
•	"Manure from animals that have grazed or eaten forage or hay harvested from treated
areas within the previous three days may only be applied to the fields where the
following crops will be grown: pasture grasses, grass grown for seed, wheat and corn."11
•	"Animals that have been fed clopyralid treated forage must be fed forage free of
clopyralid for at least 3 days before movement to an area where manure may be collected,
or sensitive crops are grown."11
8	Mambrini M, Peyraud JL. Retention time of feed particles and liquids in the stomachs and intestines of dairy cows.
Direct measurement and calculations based on faecal collection. Reprod Nutr Dev. 1997 37. 427-42. doi:
10.1051/rnd: 19970404. PMID: 9342792
9	Van Weyenberg S, Sales J, Janssens GPJ. Passage rate of digesta through the equine gastrointestinal tract: A
review. Livestock Science. 2005 99. 3-12. https://doi.Org/10.1016/i.livprodsci.2005.04.008.
10	Tsiplakou, Eleni & Hadjigeorgiou, Ioannis & Sotirakoglou, K. & Zervas, George. Differences in mean retention
time of sheep and goats undercontrolled feeding practices. Small Ruminant Research. 2011 95. 48-53.
10.1016/j.smallrumres.2010.09.002.
11	For products formulated for turf use only, registrants do not need to include this statement with reference to
grazing animals.
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Some potential impacts to clopyralid users from these measures include increased difficultly in
disposing of grass clipping and excess manure; increases in the cost of grass clipping and manure
disposal; and/or additional costs associated with storage of compost materials. Additionally,
livestock managers may have to treat only a portion of a site to have an adequate untreated area
for livestock to graze during the 3-day clean out period or may not be able to restrict grazing or
supply untreated forage for three days. The Agency acknowledges that the notification and
recordkeeping measures impose an additional burden on the applicator and the property
owner/operator. Alternatively, if a user was unable to comply with any mitigation for clopyralid,
the user may apply another herbicide without compost restrictions, if available, which could be
more costly and less efficacious.
c. Education Materials and Stewardship Plans
The Agency is requiring that educational materials on the compost issue to be developed by the
registrants and be provided to applicators, property owners/operators, and potentially other
affected stakeholders. These materials can help educate property owners/operators and livestock
producers on ways to prevent clopyralid from entering the compost stream. Having educational
materials that applicators could provide directly to landowners/operators and livestock
owners/producers may help inform these stakeholders and prevent compost contamination. EPA
also encourages educational materials to be developed for a wider audience including farmers,
compost facilities, gardeners, and other stakeholders involved in the compost waste stream.
Elements that should be part of the educational materials include:
(1)	information about clopyralid: how is it used, how residues arrive in compost, and
crops that are particularly sensitive to exposure,
(2)	information, including pictures, about the symptoms of herbicide damage (leaf
cupping, stunting, swollen stems, leaf puckering, etc.),
(3)	the persistence of clopyralid and information on how long it may last in compostable
materials and manure,
(4)	tips to prevent materials from entering the compost waste stream for hay producers,
dealers, purchasers of hay/straw, livestock and horse owners, and farmers,
(5)	methods for how farmers and gardeners using manure, compost, hay, and grass
clippings can test for persistent herbicides with their own sample pot and field bioassays,
and
(6)	any compost/manure label restrictions.
The Agency is requiring that the educational materials be available via a link on the label to
EPA's website, where applicators can access educational materials to provide to the
landowner/operator as part of the notification requirement.
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In addition, EPA is requiring stewardship plans from registrants that include information on (1)
how frequently educational materials will be updated with any new information, (2) how these
materials will be shared/distributed to applicators, land managers, livestock producers, and others
involved in the compost supply chain, and (3) how clopyralid registrants may be coordinating
efforts.
In addition, as part of discussions with the Agency on February 19, 2020, Corteva Agriscience
noted past stewardship efforts to educate stakeholders on the potential for compost
contamination from use of clopyralid. Corteva Agriscience currently has an internal stewardship
program for aminopyralid (a pyridine herbicide with compost contamination concerns) and is
working to develop a technical bulletin to inform applicators and growers about the importance
of preventing compost contamination. Corteva Agriscience has shared their plans to leverage this
existing program for clopyralid. The Agency intends to issue a DCI for stewardship plans to
ensure that all technical registrants are involved (and can collaborate) in stewardship efforts.
EPA encourages the use of existing materials that meet the elements described above for
applicators to share with property owners/operators and among the impacted compost and
clopyralid applicator community. In addition, clopyralid registrants are encouraged to develop
any other stewardship materials that may help in educating users and property owners/operators
about the unique challenges of managing pesticides like clopyralid. Some state agricultural
extension agencies have developed educational materials on clopyralid and strategies to prevent
compost contamination, which EPA encourages registrants to leverage.
d. Revision of Compost Pictogram
Some of the new clopyralid labels have a pictogram to educate users on ways clopyralid residues
can enter compost (Figure 1). For products that allow use on pasture, rangeland, hayfield,
conservation reserve program land, turf, cereal grains, corn, wheat, and other agricultural crops,
EPA is requiring a revised pictogram on these labels where the primary focus is to communicate
that manure and plant material exposed to clopyralid should not be moved offsite for composting
and provide information for how to manage treated materials. In addition to the changes to the
pictogram, a warning to limit the movement of manure and plant materials needs to accompany
the pictogram. Corteva Agriscience has generated a new pictogram (Figure 2) which it has
agreed to add to product labels. Figure 2 is an example pictogram for a label with some affected
use sites, registrants may customize the pictogram to fit registered use sites for clopyralid. While
all registrants are not required to use Corteva's pictogram, the agency requires that similar
pictograms be developed if registrants opt not use Corteva's pictogram. Any proposed
pictograms must be approved by the Agency before inclusion on the label.
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4. Spray Drift Management
The Agency is requiring label changes to reduce off-target spray drift due to risk concerns for off
field non-target plants from both aerial and ground application. The label changes will establish a
baseline level of protection against spray drift that is consistent across all clopyralid products.
Reducing spray drift will reduce the extent of environmental exposure and risk to non-target
plants and animals. Although the Agency is not making a complete endangered species finding at
this time, these label changes are expected to reduce the extent of exposure and may reduce risk
to listed species whose range and/or critical habitat co-occur with the use of clopyralid.
The following spray drift mitigation language is to be included on all clopyralid product labels
for products applied by liquid spray application. The spray drift language is intended to be
mandatory, enforceable statements and supersede any existing language already on product
labels (either advisory or mandatory) covering the same topics. The Agency is also providing
recommendations which allow clopyralid registrants to standardize all advisory language on
clopyralid product labels. Registrants must ensure that any existing advisory language left on
labels does not contradict or modify the new mandatory spray drift statements in this ID, once
effective.
•	Applicators must not spray during temperature inversions.
•	For aerial applications, do not apply when wind speeds exceed 15 mph at the application
site. If the wind speed is greater than 10 mph, the boom length must be 65% or less of the
wingspan for fixed wing aircraft and 75% or less of the rotor diameter for helicopters.
Otherwise, the boom length must be 75% or less of the wingspan for fixed-wing aircraft
and 90% or less of the rotor diameter for helicopters.
•	For aerial applicators, if the wind speed is 10 miles per hour or less, applicators must use
'/2 swath displacement upwind at the downwind edge of the field. When the wind speed
is between 11-15 miles per hour, applicators must use 3/4 swath displacement upwind at
the downwind edge of the field.
•	For aerial applications, the release height must be no higher than 10 feet from the top of
the crop canopy or ground, unless a greater application height is required for pilot safety.
•	For ground boom applications, do not apply when wind speeds exceed 15 mph at the
application site.
•	For ground boom applications, apply with the release height no more than 3 feet above
the ground or crop canopy unless making a turf, pasture, or rangeland application, in
which case applicators may apply with a nozzle height no more than 4 feet above the
ground.
•	For ground boom-less applications, there is no mandatory release height restriction due to
boom-less equipment having physical limitations for achieving a height of 3 to 4 feet.
Advisory spray drift language informing applicators to set nozzles at the lowest effective
height to help reduce the potential for spray drift is required. The droplet size for these
applications are also typically coarser, thus reducing the risk of spray drift.
•	For ground and aerial applications, applicators are to select nozzle and pressure that
deliver medium or coarser droplets in accordance with the American Society of
Agricultural & Biological Engineers Standard (ASABE S572 for ground applications and
AS ABE S641 for aerial applications).
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The required labeling is detailed in Appendix B. The Agency is requiring a restriction on droplet
size, because larger droplets have been demonstrated to decrease spray drift and, therefore,
reduce potential risks to non-target species. However, larger droplet size may lead to poor
coverage and reduced performance. Despite being translocated in plants, clopyralid must contact
foliage for effective weed management, but requiring medium or coarser droplets may not affect
the efficacy of clopyralid. However, it could affect the performance of tank mix partners that
require greater contact exposure and extension specialists estimate that more than 80% of
applicators apply herbicides in tank mixes12'13 because it allows growers to control herbicide-
resistant weeds, broadens the spectrum of weeds controlled, delays the development of resistant
weeds, and saves time and resources with one trip across the field14. Tank mixes may also allow
growers to use lower application rates than would multiple applications of single herbicides.15
Clopyralid is frequently tank mixed with other herbicides.
If reduced efficacy occurred with tank-mixed herbicides or insecticides, the Agency would
expect growers to respond by increasing the application rates (if allowed by the label), increasing
the number of applications, or replacing clopyralid with a different herbicide(s)16.
The Agency has assessed the impact of the spray drift management labeling and has concluded
that the spray drift management measures are not expected to substantially alter the way
clopyralid is used, but the requirement of a medium or coarser droplet size could impact the
efficacy of tank mix partners if smaller droplet sizes are needed.
In addition to including the spray drift restrictions and advisory language on clopyralid labels, all
references to volumetric mean diameter (VMD) information for spray droplets are to be removed
from all clopyralid labels where such information currently appears. The new language above,
which cites ASABE S572 for ground boom equipment and AS ABE S641 for aerial equipment,
eliminates the need for VMD information.
5. Non-target Organism Advisory
The Agency is also requiring the addition of a non-target organism advisory. The protection of
pollinating organisms is a priority for the Agency. Risk to pollinators from the use of clopyralid
is uncertain. It is possible that pollinators may be exposed to clopyralid from residues in pollen
12	Sprague, C. 2018. Tank-mixtures improve weed control and reduce herbicide-resistance -
Midwest. Weed Science Society of America Annual Meeting, Arlington, VA January 29
-	February 1, 2018.
13	Steckel, L. 2018. Restrictions and regulations are overwhelming at the farm level - developing a
more friendly approach. Weed Science Society of America Annual Meeting, Arlington, VA
January 29 - February 1, 2018.
14	Sprague, C. 2018. Tank-mixtures improve weed control and reduce herbicide-resistance -
Midwest. Weed Science Society of America Annual Meeting, Arlington, VA January 29
-	February 1, 2018.
15Culpepper, S. and A. York. 2018. Tank-mixtures improve weed control and reduce herbicide resistance - South.
Weed Science Society of America Annual Meeting, Arlington, VA
January 29 - February 1, 2018.
16 Chism, B., J. Becker, C. Hawkins, and S. Smearman. 2017. Effects of Mandatory Spray Droplet Size Category on
Herbicide Efficacy and Crop Yield: Potential Impacts on Sulfonylurea Registered Crops.
https://www.regulations.gov/document?D=EPA-HQ-OPP-2011-0994- 0057
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or nectar through spray drift. This may negatively impact forage and habitat of pollinators and
other non-target organisms. It is the Agency's goal to reduce spray drift whenever possible and
to educate growers on the potential for indirect effects on the forage and habitat of pollinators
and other non-target organisms. Therefore, EPA is requiring a non-target organism advisory to
be placed on clopyralid labels to address this potential concern. The advisory reads as follows:
"NON-TARGET ORGANISM ADVISORY: This product is toxic to plants and may adversely
impact the forage and habitat of non-target organisms, including pollinators, in areas adjacent to
the treated site. Protect the forage and habitat of non-target organisms by following label
directions intended to minimize spray drift."
6. Surface and Ground Water Advisories
In addition to spray drift and compost mitigation measures, EPA is requiring advisory statements
to address potential concerns with detections and persistence in surface and groundwater.
Surface Water Advisory
Clopyralid has been detected in surface water monitoring data. Clopyralid's fate properties
suggest that it has a high potential to reach surface water. For this reason, the Agency is
requiring a surface water advisory to be placed on all clopyralid labels to address this potential
concern
Non-agricultural labels are required to include the following statement:
"This product may impact surface water quality due to runoff of rain water. This is especially
true for poorly draining soils and soils with shallow groundwater. This product is classified as
having high potential for reaching surface water via runoff for several weeks after application."
Agricultural labels are required to include the following statement:
"This product may impact surface water quality due to runoff of rain water. This is especially
true for poorly draining soils and soils with shallow groundwater. This product is classified as
having high potential for reaching surface water via runoff for several weeks after application. A
level, well-maintained vegetative buffer strip between areas to which this product is applied and
surface water features such as ponds, streams, and springs will reduce the potential loading of
clopyralid from runoff water and sediment. Runoff of this product will be reduced by avoiding
applications when rainfall or irrigation is expected to occur within 48 hours."
Groundwater Advisory
Clopyralid has been detected in groundwater monitoring data. In addition, clopyralid has
environmental fate properties that indicate it has potential to persist in groundwater. For these
reasons, the Agency is requiring a groundwater advisory to be placed on all clopyralid labels to
address this potential concern:
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"Clopyralid is known to leach through soil into groundwater under certain conditions as a result
of label use. This chemical may leach into groundwater if used in areas where soils are
permeable, particularly where the water table is shallow."
The Agency anticipates minimal impacts from requiring these statements on all clopyralid end-
uses product labels as these measures are not expected to fundamentally affect how clopyralid is
used and will promote good pesticide management practices.
7.	Herbicide Resistance Management
On August 24, 2017, EPA finalized a Pesticide Registration Notice (PRN) on herbicide
resistance management.17 Consistent with the Notice, EPA is requiring the implementation of
herbicide resistance measures for existing chemicals during registration review, and for new
chemicals and new uses at the time of registration. In registration review, herbicide resistance
elements will be included in every herbicide ID.
The development and spread of herbicide resistant weeds in agriculture is a widespread problem
that has the potential to fundamentally change production practices in U.S. agriculture. While
herbicide resistant weeds have been known since the 1950s, the number of species and their
geographical extent, has been increasing rapidly. Currently there are over 250 weed species
worldwide with confirmed herbicide resistance. In the United States, there are over 155 weed
species with confirmed resistance to one or more herbicides.
Management of herbicide resistant weeds, both in mitigating established herbicide resistant
weeds and in slowing or preventing the development of new herbicide resistant weeds, is a
complex problem without a simple solution. Coordinated efforts of growers, agricultural
extension, academic researcher, scientific societies, pesticide registrants, and state and federal
agencies are required to address this problem.
EPA is requiring measures for the pesticide registrants to provide growers and users with
detailed information and recommendations to slow the development and spread of herbicide
resistant weeds. This is part of a more holistic, proactive approach recommended by crop
consultants, commodity organizations, professional/scientific societies, researchers, and the
registrants themselves.
8.	Tolerance Actions
No changes to the tolerance levels, crop groupings, or the tolerance expression are anticipated at
this time.
17 PRN 2017-2, "Guidance for Herbicide Resistance Management Labeling, Education, Training, and Stewardship"
Available at https://www.epa.gov/pesficide-regisfrafion/pesficicie-regisfration-nofices-vear
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9.	Interim Registration Review Decision
The Agency is issuing this ID in accordance with 40 CFR งง 155.56 and 155.58. EPA has made
the following interim decision for clopyralid: (1) additional data are required at this time; and (2)
changes to the affected registrations and their labeling, as described in Section IV. A and
Appendices A and B, are needed at this time to meet the FIFRA registration standard.
EPA has conducted a detailed review of the potential risks and has weighed them against the
benefits of the continued use of clopyralid in developing its interim decision. There are potential
human health risks of concern of clopyralid being an eye irritant, which is addressed with a 48-
hour REI for End-use products that contain uses that fall under the WPS. As expected for
herbicides, the greatest exceedances of ecological levels of concern are for non-target terrestrial
plants. Potential ecological risks of concern are addressed through mandatory spray drift
management language, and mitigation to prevent compost contamination which is also expected
to reduce the extent of environmental exposure and may reduce potential risks to other non-target
taxa. Any remaining risks to non-target plants and animals are outweighed by the benefits of
clopyralid as important tools for managing resistant weeds and in providing long-lasting control
of weeds in crops, rangelands, pastures, turf sites, and other non-agricultural use sites.
In this ID, the Agency is making no human health or environmental safety findings associated
with the EDSP screening of clopyralid, nor is it making a complete endangered species finding.
Although the Agency is not making a complete endangered species finding at this time, the
mitigation described in this document is expected to reduce the extent of environmental exposure
and may reduce risk to listed species whose range and/or critical habitat co-occur with the use of
clopyralid. The Agency's final registration review decision for clopyralid will be dependent upon
the result of the Agency's ESA assessment and any needed ง 7 consultation with the Services
and an EDSP FFDCA ง 408(p) determination.
10.	Data Requirements
All of the requirements of GDCI-117403-1454 have been satisfied, except for guideline
850.2300 (avian reproduction with upland gamebird), which was previously noted as
outstanding. MRID 00156001 was submitted to fulfill this data requirement, however the avian
study has not been reviewed. The Agency will review these data.
Guideline 850.6100 (environmental chemistry method for compost and associated independent
laboratory validation) was previously noted as outstanding. MRID 51074001 was submitted to
satisfy this data requirement and no further testing is needed.
The Agency anticipates issuing a DCI requiring registrants to develop additional educational
materials and a stewardship plan to educate clopyralid users on how to manage treated plant
materials and reduce the potential for compost contamination.
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V. NEXT STEPS AND TIMELINE
A.	Interim Registration Review Decision
A Federal Register Notice will announce the availability of this interim decision for clopyralid.
A final decision on the clopyralid registration review case will occur after: (1) an EDSP FFDCA
ง 408(p) determination and (2) an endangered species determination under the ESA and any
needed ง 7 consultation with the Services.
B.	Implementation of Mitigation Measures
Once the Interim Registration Review Decision is issued, the clopyralid registrants must submit
amended labels that include the label changes described in Appendices A and B. The revised
labels and requests for amendment of registrations must be submitted to the Agency for review
within 60 days following issuance of the Interim Registration Review Decision.
Registrants must submit a cover letter, a completed Application for Registration (EPA form
8570-1) and electronic copies of the amended product labels. Two copies for each label must be
submitted, a clean copy and an annotated copy with changes. In order for the application to be
processed, registrants must include the following statement on the Application for Registration
(EPA form 8570-1):
"I certify that this amendment satisfies the requirements of the Clopyralid Interim Registration
Review Decision and EPA regulations at 40 CFR Section 152.44, and no other changes have
been made to the labeling of this product. I understand that it is a violation of 18 U.S.C. Section
1001 to willfully make any false statement to EPA. I further understand that if this amendment is
found not to satisfy the requirements of the Clopyralid Interim Registration Review Decision and
40 CFR Section 152.44, this product may be in violation of FIFRA and may be subject to
regulatory and/or enforcement action and penalties under FIFRA."
Within the required timeframe, registrants must submit the required documents to the Re-
evaluation section of EPA's Pesticide Submission Portal (PSP), which can be accessed through
EPA's Central Data Exchange (CDX) using the following link: https://cdx.epa.gov/. Registrants
may instead email or send paper copies of their amended product labels, with an application for a
fast-track, Agency-initiated non-PRIA label amendment to Andrew Muench, so long as the
labels and application are submitted within the required timeframe. Please contact Andrew
Muench if you have any questions about this letter or the Interim Registration Review Decision
for clopyralid. He may be reached at muench.andrew@epa.gov.
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Appendix A: Summary of Actions for Clopyralid
Registration Review Case #: 7212
PC Codes: 117401, 117403, 117404, 11710 & 117423
Chemical Type: Herbicide
Chemical Family: Pyridine Carboxylic Acid
Mechanism of Action: mimics naturally occurring plant hormones, thereby disrupting growth
Affected
Population(s)
Source of
Exposure
Route of
Exposure
Duration of
Exposure
Potential Risk(s)
of Concern
Actions
Terrestrial
Plants
Spray Drift and
Runoff
Foliar
absorption
N/A
Growth, seedling
emergence
Enforceable and advisory spray drift reduction measures
Groundwater advisory
Surface water advisory
Terrestrial
Plants
Contaminated
Compost
Residues in
compost
N/A
Growth
Addition of label statement prohibiting residential lawn uses
Language prohibiting the off-site use of clopyralid-treated/exposed
materials or manure from animals that have grazed on treated materials for
compost and animal feed/bedding for 18 months after application
Notification and record keeping requirement for applicators to inform land
managers/operators of compost restrictions
A clean-out period of 3 days for animals that have grazed on treated plant
materials before being moved to an area where manure may be collected
Compost pictogram to inform applicators on pathways clopyralid residues
arrive in compost and animal bedding/feed
Registrant-generated stewardship and education measures
Mammals
Application to
crops, spray drift
and runoff
Dietary
Chronic
Weight
Require enforceable and advisory spray drift reduction measures

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Appendix B: Labeling Changes for Clopyralid Products
Description
Label Language for Clopyralid Products
Placement on Label

End Use Products

Mechanism of Action Group
Number
Note to registrant:
•	Include the name of the ACTIVE INGREDIENT in the first column
•	Include the word "GROUP" in the second column
•	Include the MODE/MECHANISM OF ACTION CODE in the third column
•	Include the type of pesticide {i.e., HERBICIDE or FUNGICIDE or
INSECTICIDE) in the fourth column.
Front Panel, upper right
quadrant.
All text should be black,
bold face and all caps
on a white background,
except the mode of
action code, which
should be white, bold
face and all caps on a
black background; all
text and columns should
be surrounded by a
black rectangle.
Clopyralid
GROUP
guage for herbicides from PRN 2017-1 anc
ion/DCSticidc-rcaistration-noticcs-vear)
HERBICI
HERBICIDE RESISTANCE
MANAGEMENT: Weed
Resistance Management
Include resistance management label lan
(httDs://\Yww.cDa.aov/Dcsticidc-rcaistrat
I PRN 2017-2
Directions for Use, prior
to directions for specific
crops under the heading
"WEED
RESISTANCE-
MANAGEMENT"
Restricted Entry Interval for
all WPS uses
For all products containing uses within the scope of the WPS, the REI (Restricted Entry Interval) is 48
hours.
Agricultural Use Box
Updated Gloves Statement
Update the gloves statements to be consistent with Chapter 10 of the Label Review Manual. In particular,
remove reference to specific categories in EPA's chemical-resistance category selection chart and list the
appropriate chemical-resistant glove types to use.
In the Personal
Protective Equipment
(PPE) within the
Precautionary
Statements and
Agricultural Use
Requirements, if
applicable
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Description
l.ahcl Language for ( lo|n ralid Products
Placement on l.ahcl
Non-target Organism Advisory
"NON-TARGET ORGANISM ADVISORY: This product is toxic to plants and may adversely impact the
forage and habitat of non-target organisms, including pollinators, in areas adjacent to the treated site.
Protect the forage and habitat of non-target organisms by following label directions intended to minimize
spray drift."
Environmental Hazards
Groundwater Advisory
"GROUNDWATER ADVISORY
Clopyralid is known to leach through soil into groundwater under certain conditions as a result of label
use. This chemical may leach into groundwater if used in areas where soils are permeable, particularly
where the water table is shallow."
Environmental Hazards
Surface Water Advisory for
products with no agricultural uses
"SURFACE WATER ADVISORY
This product may impact surface water quality due to runoff of rain water. This is especially true for
poorly draining soils and soils with shallow groundwater. This product is classified as having high
potential for reaching surface water via runoff for several weeks after application."
Environmental Hazards
Surface Water Advisory for
products with agricultural uses
"SURFACE WATER ADVISORY
This product may impact surface water quality due to runoff of rain water. This is especially true for
poorly draining soils and soils with shallow groundwater. This product is classified as having high
potential for reaching surface water via runoff for several weeks after application. A level, well-maintained
vegetative buffer strip between areas to which this product is applied and surface water features such as
ponds, streams, and springs will reduce the potential loading of clopyralid from runoff water and sediment.
Runoff of this product will be reduced by avoiding applications when rainfall or irrigation is expected to
occur within 48 hours."
Environmental Hazards
Removal of all residential lawn
uses for products with turf uses

Directions for Use
This restriction does not apply to
institutional turf in
athletic/recreational fields, golf
courses, parks, or grass in other
institutional/commercial areas.
Institutional turf use is defined by
40 CFR ง152.3 as any
application on turf in/around any
"Do not use on turfgrass or on ornamental grass in residential turf areas, including residential lawns.
Residential turf areas include use on turf around any structure, surface, or areas associated with the
household, including areas such as non-agricultural outbuildings, preschool, and day care facilities."

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Description
Label Language lor (lop\ r;ilid Products
Placement on Label
properly or facility that functions
to provide a service to the general
public or to public/private
organizations, including but not
limited to: hospitals, nursing
homes, schools other than
preschool and day care facilities,
museums and libraries, sports
facilities, office buildings.


Off-site Compost and animal
feed/bedding Restrictions
For products formulated for turf
use only, registrants do not need
to include the statements with
references to grazing animals.
For all products, except those that only allow application to turf:
•	"This product is persistent and may be present in treated plant materials for months to years after
application. Do not sell or transport treated plant materials or manure from animals that have
grazed on treated plant materials off-site for compost distribution or for use as animal
bedding/feed for 18 months after application."
•	"Manure from animals that have grazed or eaten forage or hay harvested from treated areas within
the previous three days may only be applied to the fields where the following crops will be
grown: pasture grasses, grass grown for seed, wheat and corn."
•	"Animals that have been fed clopyralid-treated forage must be fed forage free of clopyralid for at
least 3 days before movement to an area where manure may be collected or sensitive crops are
grown."
For products with only turf uses:
•	"This product is persistent and may be present in treated plant materials for months to years after
application. Do not sell or transport treated plant materials for compost distribution or for use as
animal bedding/feed for 18 months after application"
Additional labeling for products with turf and pasture uses:
•	"The applicator must document that they have notified property owners/operators, or customers,
in writing, of the compost and animal bedding/feed prohibitions before application of the product
occurs. Applicators must keep the records of notification for two years. This record must include
date of application, the name of the applicator, the EPA registration number of the product
applied, the area(s) treated, and a copy of the written notification provided to the property
owner/operator. Notification may be made via email, via mail, via paper handout, or by any other
written communication method. Records must be made available to State Pesticide Regulatory
Official(s), and to EPA upon request. If this information is already being retained, duplicate
records are not needed."
•	"Applications by property owners/operators on their own property are exempt from this
notification and record keeping requirement."
Directions for Use
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Description
l.ahcl Language for ( lop^ralid Products
Placement on l.ahcl

• "Applications to public land are exempt from this notification requirement."

Forage and Manure
Management Pictogram
Include forage and manure management pictogram to communicate that treated plant materials and
manure from animals that have grazed in treated areas cannot be sold or transported off-site for compost
distribution and animal feed/bedding.
In addition, this warning must be included in the pictogram:
"Warning: Do not move treated plant materials or manure from animals who have grazed on treated plant
materials to sites where manure may be collected or sensitive crops are grown."
Directions for Use
Educational Material URL
"For more information on how to manage clopyralid treated materials and to prevent clopyralid from
contaminating compost please visit httDs://www.eDa.gov/Desticide-reevaluation/registration-review-
Dvridine-and-Dv ri niidi ne-lierbicides."
Directions for Use
Spray Drift Management
Application Restrictions for all
products delivered via liquid
spray application and allow aerial
application
"MANDATORY SPRAY DRIFT MANAGEMENT
Aerial ADDlications:
•	Do not release spray at a height greater than 10 ft above the ground or vegetative canopy, unless a
greater application height is necessary for pilot safety.
•	Applicators are required to select a nozzle and pressure combination that delivers a medium or
coarser droplet size (ASABE S641).
•	Do not apply when wind speeds exceed 15 mph at the application site. If the wind speed is
greater than 10 mph, the boom length must be 65% or less of the wingspan for fixed-wing aircraft
and 75% or less of the rotor diameter for helicopters. Otherwise, the boom length must be 75% or
less of the wingspan for fixed-wing aircraft and 90% or less of the rotor diameter for helicopters.
•	If the wind speed is 10 miles per hour or less, applicators must use Vi swath displacement upwind
at the downwind edge of the field. When the wind speed is between 11-15 miles per hour,
applicators must use 3/i swath displacement upwind at the downwind edge of the field.
•	Do not apply during temperature inversions."
Directions for Use, in a
box titled "Mandatory
Spray Drift
Management" under the
heading "Aerial
Applications"
Spray Drift Management
Application Restrictions for
products that are applied as
liquids and allow ground boom
applications
"MANDATORY SPRAY DRIFT MANAGEMENT
Ground Boom ADDlications:
•	Apply with the release height no more than 3 feet above the ground or crop canopy unless making
a turf, pasture, or rangeland application, in which case applicators may apply with a nozzle height
no more than 4 feet above the ground.
•	Applicators are required to select a nozzle and pressure combination that delivers a medium or
coarser droplet size (ASABE S572).
•	Do not apply when wind speeds exceed 15 mph at the application site.
•	Do not apply during temperature inversions."
Directions for Use, in a
box titled "Mandatory
Spray Drift
Management" under the
heading "Ground Boom
Applications"
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Description
l.ahcl Language for ( lop^ralid Products
Placement on l.ahcl
Spray Drift Management
Application Restrictions for
products that are applied as
liquids and allow boom-less
ground sprayer applications
(this includes application to
roadsides and rights-of-ways)
"MANDATORY SPRAY DRIFT MANAGEMENT
Boom-less Ground SDraver ADDlications:
•	Applicators are required to select a nozzle and pressure combination that delivers a medium or
coarser droplet size (ASABE S572) for all applications.
•	Do not apply when wind speeds exceed 15 miles per hour at the application site.
•	Do not apply during temperature inversions."
Directions for Use, in a
box titled "Mandatory
Spray Drift
Management" under the
heading "Boom-less
Ground Applications"
Advisory Spray Drift
Management Language for all
products delivered via liquid
spray application
"SPRAY DRIFT ADVISORIES
THE APPLICATOR IS RESPONSIBLE FOR AVOIDING OFF-SITE SPRAY DRIFT.
BE AWARE OF NEARBY NON-TARGET SITES AND ENVIRONMENTAL CONDITIONS.
IMPORTANCE OF DROPLET SIZE
An effective way to reduce spray drift is to apply large droplets. Use the largest droplets that provide target
pest control. While applying larger droplets will reduce spray drift, the potential for drift will be greater if
applications are made improperly or under unfavorable environmental conditions.
Controlling Droplet Size - Ground Boom (note to registrants: remove if ground boom is prohibited on
product labels)
•	Volume - Increasing the spray volume so that larger droplets are produced will reduce spray drift. Use
the highest practical spray volume for the application. If a greater spray volume is needed, consider using
a nozzle with a higher flow rate.
•	Pressure - Use the lowest spray pressure recommended for the nozzle to produce the target spray volume
and droplet size.
•	Spray Nozzle - Use a spray nozzle that is designed for the intended application. Consider using nozzles
designed to reduce drift.
Controlling Droplet Size - Aircraft (note to registrants: remove if aerial application is prohibited on
product labels)
•	Adjust Nozzles - Follow nozzle manufacturers' recommendations for setting up nozzles. Generally, to
reduce fine droplets, nozzles should be oriented parallel with the airflow in flight.
BOOM HEIGHT - Ground Boom (note to registrants: remove if ground boom is prohibited on product
labels)
For ground equipment, the boom should remain level with the crop and have minimal bounce.
RELEASE HEIGHT - Aircraft (note to registrants: remove if aerial application is prohibited on
product labels)
Directions for Use, just
below the Spray Drift
box, under the heading
"Spray Drift
Advisories"
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Description
l.ahcl Language for ( lop^ralid Products
Placement on l.ahcl

Higher release heights increase the potential for spray drift.
SHIELDED SPRAYERS
Shielding the boom or individual nozzles can reduce spray drift. Consider using shielded sprayers. Verify
that the shields are not interfering with the uniform deposition of the spray on the target area.
TEMPERATURE AND HUMIDITY
When making applications in hot and dry conditions, use larger droplets to reduce effects of evaporation.
TEMPERATURE INVERSIONS
Drift potential is high during a temperature inversion. Temperature inversions are characterized by
increasing temperature with altitude and are common on nights with limited cloud cover and light to no
wind. The presence of an inversion can be indicated by ground fog or by the movement of smoke from a
ground source or an aircraft smoke generator. Smoke that layers and moves laterally in a concentrated
cloud (under low wind conditions) indicates an inversion, while smoke that moves upward and rapidly
dissipates indicates good vertical air mixing. Avoid applications during temperature inversions.
WIND
Drift potential generally increases with wind speed. AVOID APPLICATIONS DURING GUSTY WIND
CONDITIONS.
Applicators need to be familiar with local wind patterns and terrain that could affect spray drift."

Advisory Spray Drift
Management Language for
products that are applied as
liquids and allow boom-less
ground sprayer applications
"SPRAY DRIFT ADVISORIES
Boom-less Ground ADDlications:
Setting nozzles at the lowest effective height will help to reduce the potential for spray drift."
Directions for Use, just
below the Spray Drift
box, under the heading
"Spray Drift
Advisories"
Advisory Spray Drift
Management Language for all
products that allow liquid
applications with handheld
technologies
"SPRAY DRIFT ADVISORIES
Handheld Technology ADDlications:
• Take precautions to minimize spray drift."
Directions for Use, just
below the Spray Drift
box, under the heading
"Spray Drift
Advisories"
Additional Required Labelling
Action
Applies to all products delivered
via liquid spray applications
Remove information about volumetric mean diameter from all labels where such information currently
appears.
Directions for Use
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Appendix C: EPA Responses to Comments
Comment Submitted by United States Department of Agriculture (EPA-HQ-OPP-2014-
0167-0614)
Comment: USD A provided information on the benefits of clopyralid use and noted its
importance in the production of sweet corn, winter wheat, strawberries, and sugar beets. USDA
provided a brief overview of the history of issues with persistent pyridine herbicide residues in
compost, manure, and similar products. USDA is concerned with the proposed mitigation to
address compost contamination concerns. USDA commented that the regulation of the reuse of
solid waste material does not clearly fall under the regulatory purview of EPA under existing
pesticide laws. USDA are also concerned that EPA does not have enough data to inform the
proposed mitigation. USDA did not think that clopyralid contamination of organic waste
products can be addressed with only regulatory actions but needs to be addressed through
education and stewardship efforts targeted towards all impacted stakeholders. USDA offered to
facilitate further discussions between EPA and other stakeholders and offered to lead the
formation of a working group to comprehensively study and address remaining uncertainties
around the issue of persistent herbicide residues. USDA would like some of the groups focus to
be on answering to what extent herbicides are contributing to compost contamination compared
to other contaminates, what herbicide use sites are responsible for compost contamination, and
are incidents a result of applicator issues, or a result of treat material management.
USDA has specific concerns on the compost mitigation proposed in the clopyralid PID:
•	USDA does not understand why school grounds are being prohibited while other
industrial/institutional turf grass sites are not. USDA requested additional justification for
this prohibition and a more specific definition for school grounds. USDA also requests
that EPA conduct additional research on the origins of inputs to compost waste streams
before prohibiting this use site.
•	USDA supports a holding time for treated plant material before these materials are
recycled for compost. There is already an 18-month holding time on some existing labels.
USDA states that a full compost prohibition implies that applicators are responsible for
the disposal of plant materials and that there is a lack of evidence that the current 18-
month holding time on some labels is insufficient.
•	For the proposed notification and recordkeeping requirement, USDA found from
outreach discussions that professional/commercial applicators who work under contract
to provide application services for other commercial entities would be greatly impacted
by this requirement, as they play no role in determining the pesticides used. The other
group which would be impacted are private landowners who use clopyralid on their own
behalf to make applications to their own land to manage gardens, pastures, or small
timber lands. For these private owners who are mostly un-licensed, this requirement
would be unworkable and would result in use of another herbicide. USDA found that
professional/commercial applicators who work in the landscape industry or for
agricultural retailers that conduct custom spraying operations would not be significantly
impacted by the notification or recordkeeping requirement.
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•	USDA raised questions about the feasibility and logistics of the education/stewardship
component of the PID. How will registrants disseminate the education materials to
applicators? How are applicators to provide the materials to landowners/land operators?
Educational materials should be disseminated to landowners/operators in ways that are
easy to understand and convenient to stakeholders. USDA supports potential "QR codes"
on product labels that could redirect to a website with the educational information.
•	USDA advised EPA to delay the ID until all compost data can be fully reviewed.
USDA encouraged EPA to rigorously evaluate and verify all incident data submitted to the
Agency. USDA noted discrepancies in the number of compost incidents reported to EPA versus
compost incidents reported to the states and cited new compost incidents in North Carolina,
Oregon, and Montana that are not accounted for in EPA's incident summary. USDA advised
that compost incidents should be investigated to determine what specific contaminant in organic
waste products is causing injury to plants, and where that contaminant entered the supply chain.
USDA stated that many of these incidents are caused by inappropriate management of treated
materials by downstream handlers. USDA argued that the three major incident that occurred in
California, Washington, and Vermont have resulted in successful mitigation at the state level.
USDA commented that clopyralid uses and contribution to compost waste streams vary by
region and because of this state level agencies are more equipped to make regulatory decision to
address compost contamination.
Of about 30 labeled use sites identified, USDA contended that only a few have the potential for
treated plant materials to contaminate compost. The registered turf sites for clopyralid typically
do not have grass clipping removed for recycling since the clipping are too small to collect.
Exposed plant materials and manure from rangelands, hay fields, and forage sites could
contribute to compost waste streams, but many existing labels already have temporal restrictions
on the use of treated plant materials or manure for organic waste products. USDA also stated that
EPA has overlooked imported plant materials that could enter compost waste streams.
Response: EPA thanks USDA for their comments and feedback on the proposed mitigation.
EPA has limited the scope of the notification and recordkeeping requirement. Notification is
now only required for pasture and turf uses, as these uses are of most likely to contribute
clopyralid-contaminated materials into the compost stream. Property owners/operators that are
making clopyralid applications to their own land will be exempt from the notification and
recordkeeping requirement since as applicators they must already follow label directions. The
compost prohibition has been converted into an 18-month holding period where users are
prohibited from moving treated materials off-site before these materials can be recycled into
compost. This will allow for the decomposition of treated materials onsite and/or allow land
managers to reuse treated plant materials onsite. These changes will reduce the burden on
applicators and allow more flexibility for the management of treated materials, while still
targeting the use sites that contribute materials to compost.
Since the issuance of the PID, EPA has received and reviewed a non-guideline compost
dissipation study (MRID 51074001), which was classified as supplemental. The study measured
the decline of residues of clopyralid in vegetative and manure compost. Results indicate that
clopyralid declined slightly and plateaued in compost. Although the study provided useful
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information and confirmed concerns about potential residues in compost, it did not result in
changes to EPA's risk mitigation strategy for clopyralid. EPA concludes that additional compost
dissipation data is not needed at this time. There are enough compost incidents and other lines of
evidence to indicate that clopyralid has the potential to contaminate compost; based on the
weight of evidence, the Agency is moving forward with this ID and concludes that a delay is not
warranted.
The proposed prohibition of use on school grounds originated from an incident at Pennsylvania
State University in 2000 where grass clippings from the university lawn were recycled into
compost and later caused non-target plant damage. This precipitated concerns that clopyralid-
treated plant materials from industrial/institutional turf and other non-residential areas may be
collected and recycled into compost. EPA requested information during the comment period on
the types of industrial/institutional turf sites that may recycle turf clippings into compost.
Information received during the comment period indicates that most institutional turf sites are
managed by lawn care operators and in general, institutional turf clippings are not often collected
for composting in order to recycle nutrients back into the soil; this is consistent with turf best
management practices. Based on information received from stakeholders, EPA has decided to
not restrict use on school grounds or other institutional turf uses but instead retain the
notification and recordkeeping requirement for turf uses.
With respect to the concerns raised by USDA that relate to the regulation of the reuse of solid
waste material under existing pesticide laws, EPA is aware of the potential limitations associated
with pesticide labeling intended to prevent contaminated plant materials from entering the
compost supply chain. However, EPA concludes that the 18-month holding time for treated
plant materials, the notification requirement, and the education/stewardship measures outlined in
this Interim Decision are necessary to reduce the likelihood for future compost contamination
from use of clopyralid products. Based on the benefits of clopyralid, EPA is not pursuing
additional restrictions or use limitations to address these compost contamination concerns. The
18-month holding time for treated plant materials is similar to statements that already appear on
several labels. The notification requirement impacts applicators and is similar to other record
keeping requirements previously required for other pesticides.
The Agency appreciates USDA's concerns about the discrepancy in the number of compost
incidents reported to EPA vs. the number of recent compost incidents reported to various states.
There are several ways that non-target plant incidents are reported: to the National Pesticide
Information Center's (NPIC) ecological incidents portal, to the state pesticide lead agency, or
directly to EPA. Incidents reported to NPIC and to state lead agencies are subsequently reported
to EPA. However, state lead agencies have primary enforcement responsibility for pesticide
misuse violations and lead investigations into possible instances of misuse. Because it often
takes time to conduct a pesticide incident investigation, and because compost incidents due to
residues of persistent herbicides are particularly difficult to trace and verify through laboratory
testing, there may be a lag time between when states receive compost incidents and when these
incidents are then reported to EPA. EPA encourages all states to report compost incidents to the
Agency in a timely manner.
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The Agency agrees that stewardship and education should be prioritized for persistent herbicides
that may contaminate compost. EPA has been in discussions with the technical registrant,
Corteva, about the educational and stewardship measures. The Agency is requiring that
educational materials be available for download via a link on the label, where applicators can
download educational materials to provide to the property owner/operator as part of the
notification requirement. Applicators may provide notification to the property owner/operator
via email, via mail, or via paper handout—it does not matter how materials are provided, so long
as notification occurs. The possibility of a QR code on the label was considered, however, the
registrant noted that QR codes are not readily used by customers to find production information.
USDA is correct that imported plant materials could enter the compost waste stream, but the
magnitude to which this is an issue is unknown. The extent to which imported plant materials
enter the compost stream could be explored in a future working group.
EPA appreciates USDA's willingness to facilitate a working group to discuss compost
contamination concerns from persistent herbicides and to develop strategies on research,
outreach, and education efforts. EPA encourages USDA to initiate and facilitate the formation of
this working group. EPA is willing to participate and assist in these efforts. Information gathered
from this workgroup will be important to inform future pesticide decisions for persistent
herbicides. This working group could be leveraged for creating more effective educational
materials and best management practices for clopyralid and other persistent herbicides.
Comment Submitted by Corteva Agriscience (Docket ID EPA-HQ-OPP-2014-0167-0594)
Comment: Corteva stated that most of the compost incidents attributed to clopyralid are from
mismanagement of treated plant materials as the current label does not allow the use of treated
material in compost. Corteva noted that many compost incidents are based off of visual plant
effects that could have been caused by a wide variety of factors, including other pesticides,
metals, salts, and excessive nitrogen. These factors should be considered when evaluating non-
target plant incidents. A bioassay can determine when compost has the potential to cause effects
to plants. But analytical techniques should also be used to determine the presence of other
compounds, such as heavy metals and other contaminants in compost feedstock. Corteva stated
that many compost incidents could be due to improper composting techniques, such as rapid
turnaround of compost, using a high volume of inputs such as curbside grass clippings, or
composting in low temperatures or dry conditions. Corteva noted that studies have shown
clopyralid will break down in compost when composting is done correctly. Corteva also stated
that it will continue to support the restriction of products on residential turfgrass, to prevent
composting incidents.
Corteva stated that the notification and recordkeeping requirement are mostly met by existing
practices and state regulations and that this requirement will be redundant and burdensome.
Corteva also noted educational materials are available to the purchaser from the distributor, and
that the distributor is a more appropriate point of information than the applicator to communicate
the composting restrictions, as there are cases where the applicator may not have direct contact
with the landowner (e.g., for hire aerial applications).
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Corteva suggested that any requirements aimed to prevent clopyralid from entering compost
should be targeted at uses most likely to have materials recycled into the compost supply chain.
Corteva suggested to exempt private applications and applications to sites where the removal of
hay or manure is not feasible. Corteva noted that it is not feasible to remove hay or manure from
sites such as rangelands, forestry, airports, rights of ways, fencerows, industrial sites, military
lands, campgrounds, and parks.
Corteva commented that some labels already have language restricting clopyralid-treated
materials from being composted, and recommends that the existing language be required across
all labels. Corteva also suggested clarifying the 3-day clean-out period for grazing animals by
specifying animals be fed forage free of clopyralid for 3 days before movement to an area where
sensitive broadleaf crops occur.
Corteva is committed to stewardship of their clopyralid products. However, Corteva encouraged
that all registrants be held liable to the stewardship measures and asks how
enforcement/monitoring would occur.
Response: EPA appreciates Corteva's comments on the proposed clopyralid mitigation. While it
can be difficult to determine the contaminant(s) that caused a compost incident without
laboratory testing, there have been confirmed compost incidents where laboratory testing showed
the presence of clopyralid. The non-guideline compost dissipation study (MRID 51074001)
submitted by Corteva and reviewed by the Agency suggested that clopyralid does not readily
breakdown in vegetative material or manure. Due to this history of incidents and the data
available to the Agency, EPA will be requiring language that will clarify how clopyralid treated
materials should be handled and requiring that applicators for turf and pastures notify
landowners/operators to encourage the proper management of treated plant materials.
The notification requirement is not meant to be redundant; if application records are already
being kept due to state or local regulations, separate records do not need to be generated. EPA is
limiting the notification and recordkeeping label requirement to only pasture and turf uses, as
these use sites are most likely to contribute materials into compost feedstock. Property
owners/operators that are making clopyralid applications to their own land will be exempt from
the notification and recordkeeping requirement since, as applicators they must already follow
label directions. EPA is also updating the compost prohibition to focus on preventing offsite
transportation of treated materials and manure for composting and animal feed/bedding uses for
18-months after application. The Agency is also changing the animal clean out period language
to clarify that animals should not be moved to areas where manure can be collected or where
sensitive crops are grown until they have been fed forage free of clopyralid for 3 days. These
updates to the compost restrictions should provide more flexibility for stakeholders and add less
burden for applicators, while targeting mitigation at the most likely pathways for compost
contamination.
The Agency appreciates Corteva's commitment to stewardship efforts. EPA agrees that all
technical registrants should be held to the same standards, and therefore, the Agency intends to
issue a DCI for stewardship plans to encourage all technical registrants to engage in education
and stewardship efforts. EPA is updating the elements that should be included as part of
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educational materials. The Agency encourages Corteva and other registrants to leverage existing
education materials, particularly information from state extension agencies. EPA also encourages
Corteva to be a part of a future persistent herbicide working group, which USDA has proposed to
organize and facilitate, to address remaining uncertainties with respect to persistent herbicide
residues in compost.
Comment Submitted in joint letter from Oregon Department of Agriculture (ODA) and
Washington State Department of Agriculture (WSDA) (Docket ID EPA-HQ-OPP-2014-
0167-0604)
Comment: ODA and WSDA listed past issues each state has had with clopyralid compost
contamination. ODA and WSDA noted past incidents, as well as potential incidents in both
Oregon and Washington in May and June 2020, which are currently being investigated. Both
states note that current labeling and use of clopyralid puts a disproportionate burden on organic
production in the agricultural economy, as organic farms rely on compost and manure. ODA and
WSDA stated that EPA should acknowledge the economic risks that clopyralid poses to organic
producers and compost distributors. Both state agencies noted that EPA should provide guidance
and standard protocols for conducting bioassays, as bioassays are the most effective tool to avoid
the potential for phytotoxicity to sensitive plants and crops from use of compost containing
residual herbicide. ODA and WSDA suggested that EPA should require registrants to generate
data on how to best facilitate the breakdown of clopyralid in compost.
ODA and WSDA supported the proposed recordkeeping and notification requirement. ODA and
WSDA supported the composting prohibition (where treated plant materials cannot be used for
compost, mulch, or mushroom spawn). ODA and WSDA did not support the proposed holding
time for treated plant material and wanted a full compost prohibition instead as clopyralid can
persist for several years. Both state agencies argued that a holding time of several years would
not be feasible and hard to enforce. They stated that a compost prohibition would create less
confusion, less regulatory burden, and better protect compost stockpiles.
ODA and WSDA generally supported the education and stewardship measures proposed in the
PID but would like to know how EPA and the registrant plan to distribute materials. In addition,
both states requested EPA share the timeframe for developing educational materials, how
frequently materials would be updated, and how registrants plan to coordinate efforts. These
state agencies would have liked educational materials to include information on plant-back
restrictions and sensitive crop types.
ODA and WSDA stated that the proposed compost pictogram is less effective than the current
pictogram on labels. They suggested that the pictogram include a better list of treated sites, such
as cereal grains, rangeland, pasture, hayfield, wheat, corn, and conservation reserve program land
(CRP). Both state agencies would like the pictogram to retain information in the current
pictogram showing where treated materials can be used.
Response: EPA appreciates ODA's and WSDA's comments and feedback on the proposed
compost language. EPA acknowledges that compost contamination impacts the compost
community and organic farmers and gardeners that rely on manure and compost. EPA is
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converting the compost prohibition to an 18-month holding time for treated plant materials and is
limiting the notification requirement to use sites that are most likely to contribute materials into
the compost stream. The revised compost restriction focuses on preventing offsite transportation
of treated materials and manure for composting and animal feed/bedding uses. These changes
will allow treated materials to be managed onsite and clarify that treated materials should not be
transported off-site for compost distribution or for use as animal bedding/feed. While ODA and
WSDA recommended a complete compost prohibition for treated materials, EPA concludes that
a full compost prohibition is not practical as it does not allow land managers to dispose/recycle
materials onsite. In addition, it is impractical to prohibit composting forever, as this is not
practicable to enforce. The 18-month timeframe will allow some flexibility for land managers to
manage treated materials while allowing time for treated materials to fully decompose.
EPA appreciates ODA's and WSDA's feedback on the compost pictogram. The Agency has
revised the pictogram to include a better list of use sites and information on where treated
materials can be used. See Section IV of this document for the revised pictogram.
In this ID, EPA is providing additional guidance to the registrant with respect to elements that
should be included as part of the educational materials. The Agency intends to require
stewardship plans via a DCI, to ensure that all technical registrants are held to the same
standards. The anticipated DCI will note the timeframe for developing educational materials.
The Agency is requiring that educational materials be available to applicators and other
stakeholders via a link to EPA's website on the label. The Agency intends to post these
materials, when ready, online and in the clopyralid docket. EPA agrees that guidance and
protocols for bioassays should be included in educational materials to help compost facilities,
organic farmers, and gardeners test compost for potential phytotoxicity.
The Agency is not changing current plant-back restrictions on the labels for clopyralid. Plant-
back restrictions are added to labels to address dietary risk to humans and are based on crop field
trial data. EPA agrees that labels should retain information on sensitive crop types.
EPA supports USDA's proposal to facilitate a workgroup of stakeholders, which includes
registrants, states, university extension, and others, to help create best management practices for
composting and to address remaining uncertainties with persistent herbicide residues in compost.
Comment Submitted by the US Composting Council (USCC) (Docket ID EPA-HQ-OPP-
2014-0167-0102) and other Compost Stakeholders
Comment: USCC is concerned about the risks clopyralid and other persistent herbicides pose to
non-target plants via contaminated compost. USCC suggested that EPA needs to consider
compost contamination as a part of the herbicide approval and registration process. USCC
referenced multiple incidents where persistent herbicides impacted composters and caused
extensive damage. They also noted that many states have banned yard trimmings from landfill
disposal or have programs for composting and/or recycling organic materials.
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USCC is concerned that the tolerances established in the CFR for clopyralid are based on human
health and does not take compost contamination into account. They also pointed out that there
are no tolerances established in rice hulls, which can end up in compost and cause phytotoxicity.
USCC suggested ways to improve the mitigation proposed in the PID. USCC proposed that
pesticide applications should be limited to non-harvested crops and suggested that the prohibition
on residential turf be extended to all lawn use sites, with the possible exception of lawns that
keep all grass clippings on-site. USCC suggested that the notification requirement be extended to
landowner/manager to notify the purchasers and users of crops and byproducts. They also
disagreed that public land applications should be exempt from the notification requirement.
USCC stressed the importance that education materials be distributed along the compost supply
chain. They also recommended a minor revision to the compost pictogram by removing the
words "Non-cropland, rights of way, natural areas" as it is misleading.
USCC had seven suggestions to address compost contamination concerns:
1.	Limit pesticides application to non-harvested crops, while also prohibiting use on turf and
all other uses where materials are expected to be composted.
2.	Require an evaluation of persistence in compost as part of the registration process for
herbicides. This includes development of test methods and standards that registrants
must meet in order for an herbicide to receive approval.
3.	Require development of affordable compost tests that can identify herbicide
contamination at a 1 part per billion detection limit.
4.	Assign compost damage liability to all members of the supply chain: pesticide applicator,
landowner, property manager, and pesticide product distributor. Liability should include
removal or remediation of clopyralid contaminated soils or compost. Fines for misuse
should be established and the amounts should be included on the label.
5.	Prohibit retail sale of clopyralid products and limit application of clopyralid to
professional licensed applicators. Manufacturers should also provide documented training
to professional certified applicators on clopyralid's potential to contaminate compost.
6.	Require training on label restrictions, pesticide application, and identification of plant
damage by clopyralid contamination for state extension agents and educators of licensed
pesticide applicators.
7.	Require pesticide manufacturers to supply steps to remediate contaminated compost and
garden soil.
USCC's comments and suggestions were echoed in comments received by a number of private
citizens, gardeners, and compost facility managers.
Response: EPA appreciates USCC's comments and all the comments submitted by concerned
citizens, private gardeners, compost facility managers, and other compost stakeholders that
concur with USCC's mitigation suggestions for clopyralid. Compost stakeholders that agreed
with USCC comments include NewTerra, WeRadiate, Spurt industries, Terra-gro, Oregon Dairy
Organics, McFarlane's Bark, Dean Innovations Inc., Chittenden Solid Waste District, and City of
Fayetteville, Arkansas. EPA acknowledges that clopyralid and other persistent herbicides pose
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significant risks to the compost community, which have been reported in multiple incidents,
some as recent as May and June 2020.
EPA notes that tolerances are established for residues in raw agricultural commodities in
accordance with 40 CFR ง180, in conjunction with application of pesticides to crops; tolerances
are for used primarily for enforcement purposes, as well as for human health risk assessment.
Tolerances are legal limits based on the labeled use of the pesticide and are determined from the
results of numerous required studies depicting the nature and magnitude of the residue in raw
agricultural commodities and processed fractions. No such data are required or available for
compost materials, which would not be considered potential human or livestock feed items. In
the case of rice hulls, EPA does not consider rice hulls to be a significant animal or human feed
item, and therefore, no tolerances are needed.
EPA is updating the compost restriction to focus on preventing treated materials from leaving the
site of application and entering compost facilities directly or indirectly through the compost
waste stream. The required compost pictogram is also being updated for greater clarity. See
Section IV. A.3 of this document for the revised compost restrictions. EPA is not extending the
notification requirement to require landowners/operators to notify the purchasers and users of
crops and crop byproducts, since there could be implementation challenges as the label is
primarily directed towards the applicator. However, EPA is making the educational materials and
stewardship plan for clopyralid available on EPA's website and encourages communication of
the potential compost contamination concerns with others who manage crop byproducts and
compost. Public lands are exempt from the notification requirement since they are managed by
federal, state, and local authorities who are typically aware of the types of pesticides used on
these lands.
EPA's response to each of USCC's seven suggestions to reduce compost contamination are as
follows:
1.	EPA will not be limiting clopyralid application to non-harvested crops as clopyralid is
essential to managing weeds for many crops, such as sugar beets. In addition, treated
plant materials from row crop sites are not typically recycled into the compost stream.
However, the compost restriction has been updated to note that treated plant materials
cannot be moved offsite for compost and animal bedding/feed until 18 months after
application—this allows time for plant materials to decompose onsite.
2.	EPA is considering working with the registrant and other interested stakeholders (via a
workgroup as suggested earlier by USD A) on a screen for herbicides to determine the
potential for compost contamination. The Agency is working on ways to consider
compost contamination as a possible route of non-target plant exposure for structurally
similar persistent herbicides in future herbicide evaluations.
3.	A method developed by Corteva to test for clopyralid residues in compost has been
posted in the clopyralid registration review docket for use by interested stakeholders.
4.	EPA can require changes to pesticide product labels, which applicators are legally
required to follow, but due to implementation challenges EPA is only requiring
notification to land owners/operators.
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5.	EPA is not categorizing clopyralid as a restricted use pesticide, which would restrict it
for use only to certified pesticide applicators and workers under their direct supervision.
Information from USD A and states suggest that restricted use classification would not
completely address compost contamination concerns, as most compost incidents are due
to the mismanagement of treated plant materials by downstream users, not by the
applicator. However, EPA is requiring registrants develop educational materials and
stewardship plans to help inform downstream users about potential compost concerns
with clopyralid.
6.	EPA is not requiring trainings for applicators and state extension agents. This would be
burdensome and would not address compost contamination concerns. Most compost
incidents are a result of the mismanagement of treated plant materials downstream from
the time of application. EPA agrees that education and stewardship is important. The
Agency is requiring educational materials to be developed and stewardship plans to be
created and implemented by the registrant to help educate land owners/operators and
people along the compost supply chain on the potential of clopyralid to contaminate
compost. EPA encourages further development of educational materials at the state and
university extension level.
7.	An element of the educational materials EPA is requiring to be developed would include
information for compost facilities and gardeners on how to prevent and identify
clopyralid contamination. These materials may also include potential methods of
managing contaminated compost and garden soil.
USCC noted in recent correspondence (dated November 4, 2020) that it supported USDA's
proposal for a working group and wished to be a part of any discussions. The Agency looks
forward to working with USCC to create best management practices for composting and to
resolve remaining uncertainties with respect to persistent herbicides in compost.
Comments Submitted by Dean Innovations Inc. (Docket ID EPA-HQ-OPP-2014-0167-
0598)
Comment: Dean Innovations is a landscape supply company that provides organic compost.
They stated that clopyralid with its current labeling provides an unreasonable risk to the
environment due to its persistence in compost. Dean Innovations did not think the proposed
mitigations would significantly reduce the potential for compost contamination. They stated that
the proposed turf and compost restrictions would not address the issue as compost facilities are
already avoiding animal feedstock and bedding material but are still susceptible to contamination
in the compost stream. Dean Innovations also did not think the notification requirement would be
effective mitigation as compost facilities are often not in direct contact with the property
owner/operator and that the exemption of public lands from this requirement would result in a
significant amount of grazing land with even less protection. Dean Innovations supported the
mitigations proposed by USCC.
Response: EPA thanks Dean Innovations Inc.'s for its comments. EPA is altering the language
and the pictogram to help clarify that treated plant materials should not be moved off-site for
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composting. While compost facilities may not be in contact with property owner/operators,
having them be aware of the composting restrictions for treated plant materials will help prevent
these materials from being moved off-site and entering the compost waste stream. The
stewardship program will also be targeted at educating people across the compost waste stream
on methods to prevent persistent herbicide contamination of compost. Please see EPA's response
to USCC on their proposed mitigation.
Comments Submitted by the Chittenden Solid Waste District (Docket ID EPA-HQ-OPP-
2014-0167-0154)
Comment: Chittenden Solid Waste District provided information on a past incident of clopyralid
contamination in 2011 where over 600 gardens were impacted between 2012 and 2013. They
suggested that any private composting facility would have gone bankrupt if they had a similar
incident. The manager of the Green Mountain Compost facility where this large incident
occurred, is often contacted by many other composting facilities on how to deal with compost
contamination of persistent herbicides. They stated this issue is widespread in the compost
community across America. Chittenden Solid Waste District suggested very similar mitigation
for clopyralid as USCC.
Response: EPA appreciates Chittenden Solid Waste District's comment and information on the
incident they experienced. Please refer to EPA's response to USCC.
Comments Submitted by City of Fayetteville, Arkansas (Docket ID EPA-HQ-OPP-2014-
0167-0605)
Comment: Fayetteville is operating a composting operation using feedstocks from residential
yard waste and commercial food waste. They are concerned with the potential of compost
contamination from clopyralid and agree with the USCC proposed mitigations.
Response: EPA acknowledges Fayetteville's concern of clopyralid risks to compost. Residential
lawn uses for clopyralid have been canceled, so grass clippings from residential lawns should not
have clopyralid residue. Please refer EPA's response to USCC.
Comments Submitted by IR-4 Project (Docket ID EPA-HQ-OPP-2014-0167- 0581)
Comment: IR-4 Project stressed the importance of clopyralid products for controlling weeds and
invasive species for many fruit, vegetable and environmental horticultural crops, especially for
minor crops. IR-4 is concerned that label restrictions for clopyralid products on agricultural crops
are not relevant since these are either perennial crops or the vegetable crop remains are
immediately returned to the soil and do not affect rotational crops planted subsequently in the
same area to any greater extent than current label language.
Response: EPA is updating the notification and recordkeeping label requirement to be limited to
pasture and turf uses, which will eliminate this requirement for applications on crops. The
compost prohibition language has been updated to prevent offsite recycling into compost and
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animal feed/bedding. If the treated material is going to be kept onsite, the updated language
should have little burden on applicators and landowners/operators.
Comments Submitted by National Agricultural Aviation Association (NAAA) (Docket ID
EPA-HQ-OPP-2014-0167-0611) and Arkansas Agricultural Aviation Association (AAAA)
(Docket ID EPA-HQ-OPP-2014-0167-0175)
Comment: NAAA was against the requirement for clopyralid applicators having to notify
property owners and operators about clopyralid's persistence and risk of compost contamination.
NAAA stated that many aerial applicators are not involved in selecting pesticides and that if
property managers are the ones selecting chemicals, they would be aware of the risks. They also
stated that the notification requirement would be very burdensome to many aerial application
businesses. NAAA noted that agricultural crops are not responsible for clopyralid residues in
compost and suggests agricultural uses should be exempt from the notification requirement.
AAAA agreed with NAAA in their concern about the notification requirement.
In the spray drift mitigation NAAA suggested that EPA include specific language on what
altitudes where temperature inversions are not of concern.
Response: EPA appreciates NAAA and AAAA's comments. EPA is updating the notification
and recordkeeping label requirement to be limited to pasture and turf uses, which will eliminate
this requirement for agricultural crop applications. Most aerial applicators will be exempt from
the notification requirements, except for those applying on pasture; turf use sites typically do not
use aerial application. Information available to EPA suggests that aerial application to pasture is
not common, therefore, this mitigation should impact only a small proportion of aerial
applicators. At this time EPA is not changing the temperature inversion label restriction.
In response to comments about the temperature inversion restriction, EPA thanks NAAA for its
work with USDA-ARS to conduct a literature review. The Agency will review any additional
information submitted regarding the altitude of temperature inversions as it relates to pesticide
applications. At this time EPA is not changing the temperature inversion label restriction
proposed in the clopyralid PID.
Comments Submitted by American Crystal Sugar Company (Docket ID EPA-HQ-OPP-
2014-0584), Minn-Dak Farmers (EPA-HQ-OPP-2014-0167-0183), Beet Sugar Development
Foundation (EPA-HQ-OPP-2014-0167-0578), Red River Valley Sugarbeet Growers
Association (EPA-HQ-OPP-2014-0167-0591), Southern Minnesota Beet Sugar Cooperative
(EPA-HQ-OPP-2014-0167-0592), North Dakota State University (EPA-HQ-OPP-2014-
0167-0595), Western Sugar Cooperative (EPA-HQ-OPP-2014-0167-0596)
Comment: Multiple organizations commented on how important clopyralid is for sugarbeet
production, especially for controlling the glyphosate-resistant common ragweed.
Red River Valley Sugarbeet Growers Association stated that the notification requirement would
be burdensome for sugarbeet farmers renting land. Having to contact the landlord for each
application would be excessive. Southern Minnesota Beet Sugar Cooperative commented that
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since no livestock is fed sugar beet foliage the proposed grazing animal restrictions and
notification requirements would be unnecessary burdens for sugar beet growers. The Western
Sugar Cooperative noted that the proposed recordkeeping requirement is redundant as
applicators are already keeping records, and that the notification requirement is not needed since
it is the property owner's responsibility to ask for this information. The Western Sugar
Cooperative also generally supported the proposed composting label restrictions but would like
to know how long after application it is safe for grazing animals to consume treated vegetation
without needing a 3-day clean out period.
Response: EPA appreciates the comments submitted on the importance of clopyralid for the
production of sugarbeet crops. EPA is updating the notification and recordkeeping requirement
to be limited to pasture and turf uses, which will eliminate this requirement for applications on
crops like sugarbeets. EPA is also updating the compost prohibition to focus on preventing off-
site transportation of treated materials and manure for recycling into compost and animal
feed/bedding for 18-months after application. If the treated material is going to be kept onsite or
will not be transported off-site for animals feed/bedding or composting, the updated language
should have little burden on applicators and landowners/operators.
Comments Submitted by Seattle Public Utilities (Docket ID EPA-HQ-OPP-2014-0167-
0103) and Cedar Grove (Docket ID EPA-HQ-OPP-2014-0167-0153)
Comment: Seattle public utilities and Cedar Grove, a compost company in Washington,
recommended that EPA:
•	Evaluate existing and new pesticide products for persistence in compost, manure, and soil
•	Cancel pesticides that are persistent or at least limit persistent herbicide use to only
priority agricultural crops that are typically not used in compost or animal feed
•	Remove residential and landscape uses for persistent herbicides.
Seattle public utilities urged these suggested changes as they have fought to reduce clopyralid
residues in compost while supporting the composting of organics to reduce materials in landfills.
There have been incidents of compost contamination that have led facilities to discard large
amounts of compost and this has reduced the public's confidence in the quality of compost.
Response: EPA appreciates the comments submitted by Seattle Public Utilities and Cedar
Grove. EPA is considering working with the registrant and other interested stakeholders (via a
workgroup as suggested earlier by USD A) on a screen for herbicides to determine the potential
for compost contamination. The Agency is working on ways to consider compost contamination
as a possible route of exposure for structurally similar persistent herbicides in future herbicide
evaluations. While residential lawn uses have been voluntarily canceled by the registrant, EPA is
not requiring any further use cancellations. The Agency is altering label language to keep treated
materials from being moved offsite for use as compost or in animal feed/bedding. Landscaping
uses will still be permitted for clopyralid, with the exception of uses on residential lawns, but
applicators will be required to notify property owners/operators of the composting restrictions if
there are applications to turf.
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Comment Submitted by Beyond Pesticides (Docket ID EPA-HQ-OPP-2014-0167-0158)
Comment: Beyond Pesticides stated that clopyralid products pose unreasonable risks to human
health and the environment and should be cancelled. They stated that clopyralid is a dermal and
eye irritant and has also shown reproductive effects in laboratory animals. They also commented
that there is not enough data on the inert ingredients in clopyralid products, and that some can
cause human health effects. Beyond Pesticides also noted that the persistence of clopyralid in
soil, water, manure, and compost along with the impacts from spray drift pose significant risks to
the environment. They also stated that since risks have not been evaluated for endangered
species and that the endocrine disruption evaluation is incomplete reregi strati on cannot proceed.
They also argued that the risks of these products are not borne by the organizations that benefit
from its use. Beyond Pesticides recommended that organic nontoxic alternatives be used instead
of clopyralid.
Response: EPA thanks Beyond Pesticides for its comments. EPA does not agree that the
environmental and human health risk warrants cancelation. The Agency identified an
occupational post-application risk for clopyralid as an eye irritant. Because clopyralid acid is an
eye irritant, the labels require all uses that fall under the WPS to include an REI of 48 hours to
protect workers from post-application exposure. The Agency identified risk to non-target plants
and mammals. However, ecological risks are outweighed by the benefits of clopyralid in the
production of various crops and in the management of invasive weeds and other hard to treat
weed species in many settings. The Agency is requiring mitigation measures to address compost
contamination concerns, and the mandatory spray drift management measures will reduce risks
to non-target plants. EPA acknowledges that the endangered species assessment and endocrine
disruption evaluation are not complete. The Agency intends to complete ESA and endocrine
disruption evaluation prior to issuing the final registration review decision for clopyralid. Please
see Appendices E and F for further information on the endangered species assessment and the
endocrine disruptor screening program.
Comment Submitted by Iowa Turfgrass Association (Docket ID EPA-HQ-OPP-2014-0167-
0159)
Comment: The Iowa Turfgrass Association is concerned about the proposed notification
requirement as it will add extra time and confusion for applicators of golf courses and athletic
fields. They argued that golf courses and athletic fields already do an excellent job of keeping
records of when an application is made and that there are already state level regulations that
require recordkeeping in Iowa. The Iowa Turfgrass Associations also suggested that requiring
grass clipping hold times is not necessary as most clippings are left on the grass surface and not
collected. They stated the proposed compost restrictions will cause confusion for turf managers.
Response: EPA is clarifying in the notification and recordkeeping requirement that if records are
already being kept to comply with state or local requirements, then no duplicate records are
needed. EPA is also updating the compost prohibition to focus on preventing off-site
transportation of treated plant materials for composting for 18-months after application. If the
treated material is going to be kept onsite or will not be transported off-site for recycling into
compost, the updated language should have little burden on turf managers.
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Comment Submitted by the Wilbur-Ellis Company (Docket ID EPA-HQ-OPP-2014-0167-
0588)
Comment: The Wilbur-Ellis Company is concerned about the proposed notification requirement
as they think the use of the word "persistent" in the notification to property owners will create a
bias against using clopyralid. They stated that this bias will result in the overuse of alternative
herbicides and may increase weed resistance. Wilbur-Ellis suggested using a notification
statement that informs property managers that material exposed to clopyralid is not allowed to be
used in compost but omit the statement on persistence. Wilbur-Ellis also requested that EPA
provide greater flexibility on how to convey the notification to property owners to help reduce
the burden of this requirement.
Response: EPA recognizes Wilbur-Ellis Company's concern with respect to using the word
"persistent" in the notification requirement. Clopyralid is persistent, and has been known to
contaminate compost, so EPA will be retaining the word "persistent" as a descriptor for
clopyralid. EPA is reducing the amount of use sites the notification and recordkeeping
requirement applies to, focusing on applications sites of most concern (pasture and turf uses). For
pasture and turf clopyralid uses, there is no significant change in the information that must be
shared with property owners/operators for applications of clopyralid.
Comment Submitted by the Walker Supply (Docket ID EPA-HQ-OPP-2014-0167-0588)
Comment: Walker Supply noted that the required recordkeeping proposal will not be overly
burdensome for turfgrass professionals since many are already keeping these records. They are
concerned that the notification requirement for property owners should instead be needed only if
the owner requests further information as this is time consuming and unnecessary.
Response: EPA appreciates Walker Supplies' comment on the notification and recordkeeping
requirement. The notification requirement is needed to let lawn care operators inform turfgrass
property owners/operators that grass clippings treated with clopyralid cannot be moved offsite
for composting. If the notification on the 18-month offsite compost restriction is not required but
contingent on the owner/operator requesting further information, there is a risk the
owner/operator will not have the information needed to properly manage treated material in
accordance with the label.
Comment Submitted by the Roswell Recreation and Parks Department, Georgia (Docket
ID EPA-HQ-OPP-2014-0167-0593)
Comment: The Recreation and Parks Department for the city of Roswell, Georgia comments
that they have been keeping records of all chemical applications. They stated the current
application rate is safe and that clopyralid is an important chemical in turf management.
Response: EPA appreciates the comment submitted by the Roswell Recreation and Parks
Department on application recordkeeping and the application rate of clopyralid.
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Comments Submitted by Agricultural Retailers Association (ARA) (Docket ID EPA-HQ-
OPP-2014-0167-0599), Georgia Agribusiness Council (GAC) (EPA-HQ-OPP-2014-0167-
0583), and Co-Alliance (EPA-HQ-OPP-2014-0167-0608)
Comment: ARA, GAC, and Co-Alliance had concerns about the notification requirement as
they state it is not practical and will be a burden for agricultural applicators. They also found that
the treated material holding time proposal to be confusing and would increase the difficulty in
disposing grass clippings and excess manure.
Response: EPA is updating the notification and recordkeeping label requirement to be limited to
pasture and turf uses, which will eliminate this requirement for applications on agricultural
crops. The compost prohibition is being updated to prevent offsite transport of treated plant
materials/manure for use in compost and animal feed/bedding uses. If the treated materials or
manure is going to be kept onsite or will not be transported off-site, the updated language should
have little burden on applicators for agricultural row crops.
Comment Submitted by Target Specialty Products (Docket ID EPA-HQ-OPP-2014-0167-
0600)
Comment: Target Specialty Products stated that clopyralid is important for roadside and rights-
of-way weed control. They commented that the use of clopyralid helps reduce weed resistance to
other commonly used herbicides.
Response: EPA acknowledges Target Specialty Products' comment on the importance of
clopyralid for roadside and rights-of-way weed control.
Comments Submitted by Dr. James M. Breuninger, Turfgrass and Landscape Ornamental
Consultant (Docket ID EPA-HQ-OPP-2014-0167-0601)
Comment: Dr. Breuninger noted that the proposed compost mitigation for clopyralid is
redundant and unnecessary for turfgrass managers. He argued that state regulations already
require recordkeeping and that labels already ban treated plant material from being used in
compost. He also stated that clopyralid is one of the few herbicides that can be safely used on
warm and cool season grass species.
Response: EPA appreciates Dr. Breuninger's comment on the importance of clopyralid to
managing turfgrass. EPA is clarifying in the notification and recordkeeping requirement text that
if records are already being kept to comply with state or local regulations, then no duplicate
records are needed.
Comments Submitted by National Cattlemen's Beef Association (NCBA) (Docket ID EPA-
HQ-OPP-2014-0167-0606, McFaddin Enterprises (Docket ID EPA-HQ-OPP-2014-0167-
0602), and Anonymous Commenter (EPA-HQ-OPP-2014-0167-0609)
Comment: NCBA is an organization that represents the interests of cattle producers and
McFaddin Enterprises is a cattle producer. Both urged EPA to refrain from adding the proposed
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compost mitigation to clopyralid products on rangelands and pastures. They stated how
important clopyralid products are for ranchers in the southwest for controlling invasive brush on
grasslands. Both commenters noted that hay or manure from southwestern rangeland would be
unlikely to end up in compost due to low stocking rates, rotational grazing systems, and due to
the overall landscape management practices of this region. NCBA also noted that they have no
knowledge of ranchers in the arid southwest that compost manure. They stated that further
regulation on clopyralid products used for rangelands will cause further expansion of invasive
woody species and negative economic impact on the agricultural community.
An anonymous commenter who is a natural resource manager for a ranching company in south
Texas also commented on the low likelihood of southwestern ranches to collect clopyralid
treated materials for compost and that the compost mitigation is not needed for these use sites.
Response: EPA acknowledges the importance clopyralid for pasture and rangeland management.
While pasture and rangelands in the arid southwest may not contribute materials to compost,
EPA is concerned with contaminated manure from livestock across the United States entering the
compost stream as there have been compost incidents from contaminated manure. Further
information from stakeholders has indicated that manure and plant materials from rangelands are
unlikely to be collected and used for offsite compost. There is concern that pastures may be
hayed, and hayed materials can be used as animal bedding/feed. The potential risk of
contaminated materials being moved offsite from pastures is why EPA is keeping the notification
and recordkeeping requirement, and compost mitigation for pasture sites. The compost
prohibition is also being updated to prevent offsite transport for use in compost and animal
feed/bedding uses for 18 months after application. If the treated material is going to be kept
onsite or will not be transported off-site for animals feed/bedding or compost use, the updated
language should have little burden on ranchers. The updated compost language will provide
more flexibility for property owners/operators to manage treated materials onsite.
Comments Submitted by Responsible Industry for Sound Environment (RISE) (Docket ID
EPA-HQ-OPP-2014-0167-0607) and CropLife America (CLA) (EPA-HQOPP-2014-0167-
0613)
Comment: RISE noted the importance of clopyralid as an important tool for controlling weeds
and woody species while also being a selective herbicide. RISE is concerned about the proposed
compost mitigation. RISE noted that for compost incidents from 1998-2003, EPA and registrants
took action to adequately address these concerns. RISE and CLA are particularly concerned
about the proposed notification and recordkeeping requirement as it would pose an unnecessary
burden on applicators. RISE is concerned the notification requirement is impractical in many
cases as the applicator (such as an aerial applicator) is not always in contact with the property
owner. RISE argued that many use sites like rights-of-way or utility lines rarely have materials
collected for composting and those use sites should not have the notification or recordkeeping
requirements. RISE also disagreed with EPA's proposal to remove school lawns as a use site as
this is not a residential use but is an institutional use. RISE stated that the proposed 3-day
holding time for grazing animals and the compost prohibition for clopyralid treated material will
inflict significant burdens on property managers and livestock producers, making disposal of
these materials difficult.
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Both CLA and RISE would like EPA to develop guidelines and a standard process for
determining which pesticide active ingredients and use patterns require compost studies. They
stated this will bring greater stability and consistency to the review process for herbicides.
Response: EPA is updating the notification and recordkeeping label requirement to be limited to
pasture, and turf uses, which will eliminate this requirement for applications on agricultural
crops, rights-of-ways, and utility lines. Aerial applications are typically not used in pasture, and
turf sites, so aerial applicators should have little impact by the notification requirement. EPA is
also updating the compost prohibition to focus on preventing off-site transportation of treated
plant materials for compost and animal feed/bedding use for 18-months after application. If the
treated material is going to be kept onsite or will not be transported off-site, the updated
language should have little burden on landowners/operators. EPA is not prohibiting clopyralid
uses on school grounds since stakeholders note that institutional turf sites, such as school lawns,
are generally managed by lawn care operators and turf clippings at these sites are frequently left
onsite to decompose in order to improve soil nutrition. Animals that have grazed on treated
materials must be fed forage free of clopyralid for 3 days before being transported to land where
manure may be collected for compost purposes, to ensure this manure will not contain
clopyralid.
EPA is considering working with the registrant and other interested stakeholders (via a
workgroup as suggested earlier by USD A) on a screen for herbicides to determine the potential
for compost contamination. The Agency is working on ways to consider compost contamination
as a possible route of exposure for structurally similar persistent herbicides in future herbicide
evaluations.
Comment Submitted by Golf Course Superintendents Association of America (GCSAA)
(Docket ID EPA-HQ-OPP-2014-0167-0618)
Comment: GCSAA noted the importance of clopyralid products for managing weeds in golf
courses. They stated many golf courses mulch clippings back into the turf, but some golf courses
do remove clippings that eventually go into the compost stream. For the notification and record
keeping requirement, GCSAA noted that the golf course superintendents are usually considered
the property operator and they manage the pesticide application so their general recordkeeping
should suffice. In the case where superintendents hire a pesticide application contractor, they
would be required to provide a notification, which GCSAA stated is likely already happening.
Recordkeeping has also been kept for many golf courses since this is already a requirement in
many states.
Response: EPA appreciates GCSAA's comment on the importance of clopyralid to golf course
weed management and the feedback on the proposed mitigation. The notification and
recordkeeping requirements are being updated to exempt property owners or operators from this
requirement if applying to their own property. This means golf course property operators making
their own clopyralid application would not be required to notify themselves. EPA is also
updating the compost prohibition to focus on preventing off-site transportation of treated
materials and manure for compost and animal feed/bedding uses for 18-months after application.
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If the treated material is going to be kept onsite or will not be transported off-site for animals
feed/bedding or compost use, the requirements should have little burden on golf courses.
Comments Submitted by a Mass Mail Campaign of Concerned Citizens (Docket ID EPA-
HQ-OPP-2014-0167)
Comment: Hundreds of comments were submitted by private citizens that were concerned with
the persistence of clopyralid and potential residues in compost. Many urged EPA to consider
USCC's comment and their mitigation proposals. Many of the commenters were from Oregon,
which recently had a clopyralid compost contamination incident. Commenters claimed they
bought compost for their garden that adversely impacted their plants and think clopyralid
contamination was the cause. A portion of the comments advocated for clopyralid to be banned
and for EPA to stop the flow of pesticides into their community.
Response: EPA acknowledges the concern about clopyralid's impacts on the compost and
gardening community. EPA has considered and responded to USCC's comment and mitigation
suggestions. While it is difficult to prove that clopyralid is the cause of adverse impacts to plants
in individual gardens without laboratory testing, EPA does acknowledge that there were
clopyralid compost contamination incidents in Oregon and Washington that occurred in May and
June 2020. While EPA is not cancelling the use of clopyralid due to its benefits in the production
of various crops and its efficacy on various weed species, the Agency is requiring further
mitigation for clopyralid to prevent compost contamination.
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Appendix D: Compost Incidents Reported to EPA for Clopyralid
Incident
number
Year
State
Legality
classification
Certainty
index
Affected
species
Incident Summary
1025047-
001
2013
TX
Undetermined
Possible
Unknown
Plant
A grower applied 3 tons of cow manure from a local feed in Mason
County, TX, now nothing grows on his land. The grower claims the
manure may be contaminated with picloram, clopyralid and aminopyralid.
1012627-
001
2002
WA
Undetermined
Highly
Probable
Tomato
A vegetable farmer in Bainbridge Island, Washington needed a source of
manure to make compost for his 1.5-acre farm; he turned to his neighbor's
horse. The grower agreed to take away the manure, mixed with straw
from the horse's stall. Within eight days of planting, most of the tomatoes
he put in holes enriched with his homemade compost were dead. The soil
tested positive for clopyralid contamination.
1024382-
001
2012
VT
Undetermined
Highly
Probable
Unknown
Plant
During 2012 in Chittenden County, VT, the Chittenden Solid Waste
District detected picloram and clopyralid in their compost. At least 300
gardening victims of the herbicide contamination have reported plant
damage/death to the solid waste district.
1012363-
002
2000
PA
Registered Uses
Highly
Probable
Herb, leafy
vegetables,
pepper
In the fall of 2000, Penn State University experienced plant growth
problems in a greenhouse that was related to clopyralid contamination of
compost. Clopyralid found in the compost was traced to the vegetative
debris collected from the university lawn. Leaves from 300 acres of
treated lawn were collected by leaf vacuum and used for compost.
Investigations showed that some of the leaves were over-sprayed with
clopyralid during applications made in September and October. Although
separate collections of grass clippings were not used in the compost, there
was some residual grass clippings that was collected with the leaves. A
high percentage of the material used for composting contained clopyralid
residues. Dow AgroSciences is working to develop a revised product use
label that will ensure that homeowners and other turf customers are
informed about the restrictions regarding composting and mulching. A
paper produced by the researchers at The Pennsylvania State University
(1020951-001) provided more details about this incident. In June 2000,
herbicide toxicity symptoms were first observed in experimental bell
pepper plots grown in high tunnel greenhouses with soils amended with
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compost at various rates. Initial testing revealed that the compost used on
bell peppers contained clopyralid at 17 ppb. Symptoms were again
observed in the research plots in June of 2001. Though less severe than
the first year, the effects indicated that clopyralid can cause adverse effects
for more than two years after the compost is incorporated into the soil.
Plants in some of the plots began to re-exhibit mild symptoms of
clopyralid toxicity in September and October. Further soil testing was
done. Clopyralid was found in 9 out of 10 soil samples at concentrations
between 3.8 and 25 ppb. Concentration were greatest in shallow compost
in drier areas (away from the drip irrigation). Clopyralid symptoms were
also observed in leafy vegetable and herb crops beginning four weeks after
transplanting. Chard, spinach, and parsley exhibited the most severe
symptoms. Analysis of plant tissue of various crop found detectable levels
of residues only in pepper fruit sample (4.5 ppb) and one variety of lettuce
(5 ppb). No residues were detected in most of the vegetation samples
despite the fact they showed obvious symptoms. The researchers
concluded that the low moisture caused by use of drip irrigation and high
organic matter content of the soils used made them conducive for the
persistence of clopyralid. Lab analysis of finished compost detected
clopyralid residues between 10 and 75 ppb. Residues in samples of
collected leaves ranged from 36 to 354 ppb. Residues in a sample of grass
separated from collected leaves was 573 ppb. No detectable levels of
clopyralid were found in leaves collected from trees. However, clopyralid
was detected in fallen leaves collected by hand off the ground. It was
concluded that clopyralid in compost came from small quantities of grass
that were inadvertently collected with the leaves, as well as possible
sequestering of the compound by trees into the leaves before they fall in
the autumn.
1010414-
001
2000
WA
Misuse
Probable
Tomato
Dow reported a letter it had received from the Washington State Dept. of
Agriculture to the effect that there were two complaints regarding the
damaging effects of compost from the regional compost facility on Elk-
Chattaroy Road, near Colbert, WA. The problem was that grass clippings
being composted had traces of clopyralid (CONFRONT) which were not
degraded during the 60-90 day composting period at the plant. When this
compost material was used in the potting soil of greenhouses, it had a
detrimental effect on plants. With tomato plants, for example, the
symptoms are cupping of leaves, slight bending or twisting of stems,
fiddleneck appearance of new growth, and sometimes even accelerated
growth. There is a warning on the label saying that compost containing
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grass clippings that had been treated with clopyralid should not be used in
the growing season of application.
1012627-
002
2002
WA
Registered Uses
Probable
Tomato
To comply with 6(a)2 requirements, Dow reported a newspaper account
(Seattle Times, Jan. 22, 2002) concerning the effects of clopyralid on
compost piles. In 1012627-001 can be found the plight of a farmer whose
tomato plants were damaged when he used, as compost, the manure from a
neighboring horse stall; straw for the stall had come from an area in which
clopyralid had been applied. The newspaper account goes on to state that
"Regulators tested for clopyralid at nine compost manufacturers around
the state in October, and found (clopyralid) residue in the ingredients or
the finished compost in each one." Tests of the soil that had been the
focus of 1012627-001 showed that damage occurred to some plants that
were exposed to just three parts per billion clopyralid.
1012628-
002
2002
CA
Registered Uses
Probable
Unknown
Plant
An Internet account of the Los Angeles Times of March 7, 2002, was
entitled "In the Garden: Coping with Culprit in Compost Gone Bad." It
concerns the growing problem of clopyralid that has found its way into
compost piles after having been applied to lawns. This phenomenon has
been reported often in 2001, generally in conjunction with the State of
Washington. The reason for writing up this incident is to report that the
San Diego Environmental Services Department has found clopyralid in
compost processed from Southern California grass clippings. The
California Dept. of Pesticide Regulation has announced that the chemical
is under review. There were reassuring words from the director of the
Washington State University compost operations at the Pullman campus.
He pointed out that California is lucky because clopyralid had been used
there only since 1997, whereas it has been in use in Washington for 10
years longer.
1012628-
003
2002
CA
Registered Uses
Probable
Unknown
Plant
Same as 1012628-002
1025960-
001
2013
VT
Misuse
Highly
Probable
Tomato,
unknown
plant
Aminopyralid, clopyralid and picloram were reported detected in Green
Mountain Compost's compost during the spring of 2013 in Chittenden
County, VT. Aminopyralid apparently entered the in manure from horses
that consumed feed treated with products containing aminopyralid.
Picloram reportedly entered the manure from grass clippings.
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ODA
incident
#200405
(EPA
incident
number not
yet
assigned)
2020
OR
Not yet
classified
Not yet
classified
Unknown
plants
The Oregon Department of Agriculture (ODA) received reports of
contaminated soil purchased from a supplier in Portland. Samples tested
positive for clopyralid. Three potential sources of contamination were
identified: mushroom compost from Yamhill, Oregon, mushroom compost
from Olympia, Washington, and cow manure from Walla Walla,
Washington. Sampling at the Yamhill, Oregon source revealed that the
straw and canola meal used in the mix to grow mushrooms contained
clopyralid. The canola meal was obtained from a merchandiser of feed
commodities in California. The straw is purchased from a company based
in Hermiston, Oregon, and local straw producers. The complexity of the
straw origins makes it difficult to trace the source of contamination.
ODA
incident
#200408
(EPA
incident
number not
yet
assigned)
2020
OR
Not yet
classified
Not yet
classified
Tomato
plants
The ODA received a complaint of contaminated compost. Damage to
tomato plants was observed at the site and lab analysis found residues of
clopyralid. It was discovered that the mushroom compost used came from
a source in Yamhill, OR (see ODA incident #200405), which had
clopyralid present in their compost but had not made any pesticide
applications.
ODA
incident
#200481
(EPA
incident
number not
yet
assigned)
2020
OR
Not yet
classified
Not yet
classified
Unknown
plants
The ODA received two complaints of suspected herbicide-contaminated
compost. Vegetation and soil samples from the affected properties and the
compost supplier were analyzed. Lab analysis found residues of
clopyralid in all samples taken. The source of the compost was traced to a
supplier in Yamhill, OR (see ODA incident #200405) who had clopyralid
present in their compost but did not make any pesticides applications.
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Appendix E: Endangered Species Assessment
In 2013, EPA, along with the Fish and Wildlife Service (FWS), the National Marine Fisheries
Service (NMFS), and the United States Department of Agriculture (USD A) released a summary
of their joint Interim Approaches for assessing risks to endangered and threatened (listed) species
from pesticides18. These Interim Approaches were developed jointly by the agencies in response
to the National Academy of Sciences' (NAS) recommendations that discussed specific scientific
and technical issues related to the development of pesticide risk assessments conducted on
federally threatened and endangered species.
Since that time, EPA has conducted biological evaluations (BEs) on three pilot chemicals
representing the first nationwide pesticide consultations (final pilot BEs for chlorpyrifos,
malathion, and diazinon were completed in January 2017). These initial pilot consultations were
envisioned to be the start of an iterative process. The agencies are continuing to work to improve
the consultation process. For example, after receiving input from the Services and USDA on
proposed revisions to the pilot interim method and after consideration of public comments
received, EPA released an updated Revised Methodfor National Level Listed Species Biological
Evaluations of Conventional Pesticides (i.e.. Revised Method) in March 2020.19 During the same
timeframe, EPA also released draft BEs for carbaryl and methomyl, which were the first to be
conducted using the Revised Method.
Also, a provision in the December 2018 Farm Bill included the establishment of a FIFRA
Interagency Working Group (IWG) to provide recommendations for improving the consultation
process required under section 7 of the Endangered Species Act for pesticide registration and
Registration Review and to increase opportunities for stakeholder input. This group includes
representation from EPA, NMFS, FWS, USDA, and the Council on Environmental Quality
(CEQ). Given this new law and that the first nationwide pesticide consultations were envisioned
as pilots, the agencies are continuing to work collaboratively as consistent with the congressional
intent of this new statutory provision. EPA has been tasked with a lead role in this group, and
EPA hosted the first Principals Working Group meeting on June 6, 2019. The recommendations
from the IWG and progress on implementing those recommendations are outlined in reports to
Congress.20
Given that the agencies are continuing to work toward implementation of approaches to assess
the potential risks of pesticides to listed species and their designated critical habitat, the
ecological risk assessment supporting this ID for clopyralid does not contain a complete ESA
analysis that includes effects determinations for specific listed species or designated critical
habitat. Although EPA has not yet completed effects determinations for specific species or
habitats for this ID, EPA's evaluation assumed, for all taxa of non-target wildlife and plants, that
18	https://www.epa.gOY/endangered-species/draft-revised-niethod-national-level-endangered-species-risk-
assessment-process
19	https://www. regulations. gov/document?D=EPA-HQ-OPP-2019-0185-0084
20	https://www.epa.gov/endangered-species/reports-congress-improving-consnltation-process-niider-endaiigered-
species-act
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listed species and designated critical habitats may be present in the vicinity of the application of
clopyralid. This will allow EPA to focus its future evaluations on the types of species where the
potential for effects exists once the Revised Method has been fully implemented. Once that
occurs, the Revised Method will be applied to subsequent analyses for clopyralid as part of
completing this registration review.
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Appendix F: 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, sub-chronic 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 clopyralid, 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 ง 408(p), clopyralid 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 ง 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. The Agency has reviewed
all of the assay data received for the List 1 chemicals and the conclusions of those reviews are
available in the chemical-specific public dockets. A second list of chemicals identified for EDSP
screening was published on June 14, 2013,21 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. Clopyralid is not on either list. 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 EPA website.22
In this ID, EPA is making no human health or environmental safety findings associated with the
EDSP screening of clopyralid. Before completing this registration review, the Agency will make
an EDSP FFDCA ง 408(p) determination.
21	See http://www.reaulations.gov/#!documentDetail:D=EPA-HO-OPPT-2009-0477-0Q74 for the final second list of
chemicals.
22	https://www.epa.gov/endocrine-dismption
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