Date:

Chemical:

PC Code:

DPBarcode:

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON; D.C. ZO~l;O

ornCE OF PREVEm'ION, PF$TlCIDl?S

AND TOlClC SlmSTANCES

January 22. 2010

Aminocyclopyrachlor

288008,288009,288010

DP 358167

MEMORANDUM

SUBJECT: Transmittal Memo regarding the "Ecological Risk Assessment for the Section 3

New Chemical Registration of Aminocyclopyrachlor on Non-crop Areas .md Turf'

FROM:

TO:

Anita Ullagaddi, M.S., Environmental P~otectiO~~egialit

Christopher M. Koper, M.S., Chemist "i(: '2.:1.. 3J\1,; J,.(1l0

Y

o--! ....-Anita Pease, M.S., Acting Branch Chief 'frr h /'

Environmental Risk Branch I .

Environmental Fate and Effects Division (7507P)

Jim Tompkins. Risk Manager

Mindy Dodish, Risk Manager Reviewer

Registration Division (7505P)

EJ. du Pont de Nemours and Company (DuPont) submitted a petition to the Environmental

Protection Agency (EPA) to register the new chemical aminocyclopyracW r. DuPont proposed

two technical active ingredients (aminocyclopyrachlor acid and aminocyclopyrachlor methyl

ester). The acid can also be fonnulated into aminocyclopyrachlor potassium salt. The proposed

uses are on non-crop areas and turf for pre- and post-emergent control of broadleaf weeds and

grasses. This memorandum summarizes the attached Environmental Fate and Effects Division

(EFED)'s ecological risk assessment for aminocyclopyracWor for the proposed uses.

Five technical and manufacturing concentrate labels and 29 labels for formulations were

submitted under DP 368239 and 358167. EFED's assessment is based on all 29 end-use product

labels. However, it was brought to EFED's attention on January 21, 2010 that some labels may

be withdrawn. The exact number of labels and their identity that may be withdrawn were

unknown at the time this assessment was completed. Because the proposed action to withdraw

labels for consideration for registration bas not been received by EFED, thIS assessment includes
all 29 labe1s submitted under DP 368239 and 358167. If the registrant proposes to remove

specified labels from considerationJQr regi~tration, then EFED will submjt an addend~m tQ t1l~

attached ecological risk assessment if the remaining labels do not reflect the assessed uses.

Table A shows examples of the proposed application rates for the uses that have been modeled

for this ecological risk assessment. See Table 3.1 for a complete table containing all maximwn

proposed application rates for the 29 submitted product labels.

Table A. Maximum Application Rates from tbe Proposed Aminocvclo .vrachlor Labels

Application Single Application Rate Max. # of Maximum

Compound Use Method' (Interval between Applications1 AppUcatiOD

Annlicationsl Rate/Year

Non-Crop Aerial or 0.284 Ib a.eJA Ground - I 0.284 Ib a.e .fA

Aminocyclopyrachlor WDG (NA)

Acid 0.108tb a.eJA Turf Ground - G (30 days) 3 0.324 Ib a.e JA

NA = Not Applicable

l WDG = waler dispersible granule; SC =soluble concentrate; G =granule.

Iff not specified on label, number of applications may have been calculated based on maximum single application rate and

maximum annual application rate.

Risks to Non-target Organisms ... A screening-level risk assessment based on proposed uses suggests that aminocyclopyrachlor

presents potential risks to both non-listed and listed terrestrial plants and 10 organisms that

depend on terrestrial plants for habitat and forage. Due to lack of acceptable avian reproduction

and freshwater invertebrate life cycle toxicity data, chronic risks to non-listed and listed birds

and freshwater and estuarine/marine invertebrates are assumed.

Outstanding Data Requirements

No additional environmental fate data are recommended for request at this time.

Several additional environmental effects studies were identified as data gaps (see Section 2.6.2).

The following two studies are high priority studies because they have the potential to add value

to the assessment by characterizing potential risks by eliminating uncertainties for both nonlisted and listed species that cannot be accounted for using alternate methods or weights or

evidence.

Acid

• Avian Reproduction Toxicity Test (850.2300): Data are required for both an upland game

and waterfowl species for the proposed use patterns. The submitted studies were classified as

invalid due to improper husbandry practices (cage sizes that were much smaller than those

recommended in the guideline) that may have caused incidental mortalities in quails and reduced

2
egg production in mallards (see Section 4.2.1). Because of the lack of avian reproduction data,

potential chronic risks to birds cannot be precluded for non-listed and listed species.

• Freshwater Invertebrate Life Cycle Toxicity Test (850.1300): Non dose-response

mortalities were observed in the three lowest treatment levels (40%, 30%, and 40%, respectively)

for the submitted freshwater daphnid study. Therefore, a NOAEC could not be established. Due

to the high mortality observed in the first three treatment levels, the resulting toxicity values are

not a reliable estimate of the chronic toxicity to water fleas (see Section 4.1.2 for details).

Recommended Labeling Language

Following review of physicochemical properties and incident data ofsimilar registered

chemicals, EFED recommends that the following language be placed on all aminocyclopyrachlor

labels:

Surface Waler Advisory

This product may impact surface water quality due to spray drift and runo)jofrain water. 771is is

especially true for poorly draining soils and soils with shallow ground water. This product is

classified as having high potentialfor reaching surface water via runofffor several months after

application. A level, well-maintained vegetative buffer strip betwee/~ areas to which this product

is applied and surface waterfealures such as ponds, streams, and springs will reduce lhe

pOlenlialloading ofaminocyclopyrachlorfrom runoffwater and sediment. RIUlOffofthis product

will be reduced by avoiding applications when rainfall isforecast to occur within 48 hours.

See manual at the following Internet address:

http://www.wsi.nrcs.usda.gov/products/\¥2Q/pesvcore4.html

Ground Waler Advisory

This chemical has properties and characteristics associated with chemicals detected in ground

water. This chemical may leach into ground water If used in areas where soils are permeable,

particularly where the water table is shallow.

Residues in Plants or Manure

Do not use plant residues including grass or hay fr.om trealed areas or manure from animals

being fed treated forage or hay for composting or m"lching ofdesirable, susceptible broadleaf

plants.

Do not use manurefrom animals grazing treated areas on land IIsedfor growing broadleaf

crops, ornamentals, orchards or other susceptible, desirable plants. ManllTe may contain enough

aminocyclopyrachlor to cause injury to susceptible plants.

[n addition, EFED has concerns with spray drift management language on the proposed labels.

The recommended droplet sizes (>150 to 200 microns) on the proposed labels are consistent with

fine droplets according to the American Society of Agricultural and Biological Engineers

(ASABE). The label characterizes these droplets as "large". Assuming large droplets are similar

to course droplets as defined by ASABE, the volume median diameter (YMD) should be >326

microns. Recommended droplet sizes on the proposed labels need to be consistent with ASABE

classifications of droplet size.

3
Ecological Risk Assessment for the Section 3 New Chemical

Registration of Aminocyclopyrachlor on Non-crop Areas and Turf

o

OH

CAS: 858956·08·8 (acid), 858954·83·3 (esler), 858956·35·1 (sail)

U.S. EPA PC Code: 288008 (acid), 288009 (esler), 288010 (sail)

Team Members

Anita UUagaddi, M.S., Environmental Protection Specialist

Christopher M. Koper, M.S., Chemist

Peer Reviewers

Christine Hartless. Ph.D., Wildlife Biologist

James Lin, Ph.D. Environmental Engineer

Acting ERBI Branch Chief

Anita Pease. M.S.

Dale of Approval

January 22, 2010
TABLE OF CONTENTS 

1 Executive Summary .................................................................................................................................... 4 

1.1 Nature of Chemical Stressor ...................................................................................................................... 4 

1.2 Potential Risks to Non-target Organisms ................................................................................................... 5 

.................................................................................................. 1.3 Conclusions: Exposure Characterization 6 

1.4 Conclusions: Effects Characterization ....................................................................................................... 7 

1.5 Data Gaps ................................................................................................................................................... 8 

2 Problem Formulation ........................................................................................................................................ 8 

2.1 Nature of Regulatory Action ...................................................................................................................... 8 

2.2 Stressor Source and Distribution ................................................................................................................ 9 

2.2.1 Nature of the Chemical Stressor ................................................................................................................. 9 

Mode of Action ........................................................................................................................................ 11 

Environmental Fate and Effects Bridging Strategy .................................................................................. 11 

Overview of Pesticide Usage ................................................................................................................... 13 

Receptors .................................................................................................................................................. 13 

Aquatic and Terrestrial Effects ................................................................................................................ 13 

Ecosystems Potentially at Risk ................................................................................................................ 13 

Ecological Effects .................................................................................................................................... 14 

Conceptual Model .................................................................................................................................... 14 

Risk Hypotheses ....................................................................................................................................... 14 

Conceptual Diagram ................................................................................................................................. 15 

Analysis Plan ............................................................................................................................................ 16 

Measures of Effect and Exposure ............................................................................................................. 16 

Data Gaps ................................................................................................................................................. 17 

3 Exposure Analysis ............................................................................................................................................ 20 

3.1 Use Characterization ................................................................................................................................ 20 

3.2 Exposure Assessment ............................................................................................................................... 24 

3.2.1 Environmental Fate and Transport Characterization ................................................................................ 24 

3.2.2 Aquatic Exposure Estimates for Aminocyclopyrachlor ........................................................................... 32 

3.2.3 Terrestrial Wildlife Exposures ................................................................................................................ 35 

3.2.4 Terrestrial and Semi-Aquatic Plant Exposures ......................................................................................... 36 

4 Ecological Effects Analysis .............................................................................................................................. 37 

4.1 Aquatic Effects Summary ........................................................................................................................ 37 

4.1.1 Toxicity Effects on Fish .......................................................................................................................... 37 

4.1.2 Toxicity Effects on Invertebrates ............................................................................................................. 38 
Toxicity Effects on Plants ........................................................................................................; .............. 40 

Terrestrial Effects Summary ..................................................................................................... I .............. 41 

Toxicity Effects on Birds .......................................................................................................... :.............. 41 

Toxicity Effects on Mammals .................................................................................................................. 43 I 

Toxicity Effects on Invertebrates ............................................................................................. .............. 44 

I Toxicity Effects on Plants ........................... 1.. ........................................................................... 1........... $45 

Comparison of Ester and Acid Toxicity .................................................................................................. I 46 

Review of Incident Data ........................................................................................................................... 47 I 

Review of ECOTOX Data ...................................................................................................... 1 ............ 47 I 

5.1.3 . Terrestrial and Semi-aquatic Plants ......................................................................................................... 1 50 

5 Risk Characterization .................................................................................................................................... 1 47 

5.2 Risk Description ...................................................................................................................................... 5 1 I 

5.2.1 Risks of Aminocyclopyrachlor to Aquatic Organisms ............................................................................ 51 

5.2.2 Risks of Arninocyclopyrachlor to Terrestrial Organisms ........................................................... ............. 52 

i 

i 5.2.3 Potential Risks Due to Exposure to the Degradates ............................................................................. 54 

I 5.3 Threatened and Endangered Species Concern ........................................................................................ 57 I 

5.1 Risk Estimation: Integration of Exposure and Effects Data ..................................................................... 

5.1.1 Non-target Aquatic Fish, Invertebrates, and Plants .................................................................................. 

5.1.2 Non-target Terrestrial Animals ................................................................................................................ 

5.3.1 Action Area ............................................................................................................................................ 57 

5.3.2 Taxonomic Groups Potentially at Risk: Direct Effects .......................................................................... 1 58 

i 

5.3.3 Use of Probit Slope Response Relationship to Provide Information on the Endangered specie+ Levels of 

Concern ................................................................................................................................... .........I.. .......... .59 I 

47 

48 

49 

i 5.3.4 Indirect Effects Analysis .......................................................................................................................... 59 I 

7 Literature Cited .............................................................................................................................................. 1 64 

6 Description of Assumptions, Uncertainties, Strengths, and Limitations ................................................... 1 59 

6.1 Assumptions and Limitations Related to Exposure for all Taxa ................................................. ........... 59 

6.2 Assumptions and Limitations Related to Exposure for Terrestrial Species ............................................ 60 i 

6.3 Assumptions and Limitations Related to Exposure for Aquatic Species ................................................ 

6.4 Assumptions and Limitations Related to Effects Assessment .................................................................. 

62 

62 
1 Executive Summary 

1. Nature of Chemical Stressor 

E.I. du Pont de Nemours and Company (DuPont) is seeking registration for 

aminocyclopyrachlor, an herbicide in the pyrimidine carboxylic acids class within the family of 

synthetic auxins. Aminocyclopyrachlor is proposed for registration in three different forms. 

Aminocyclopyrachlor acid (DPX-MAT28, referred to as the acid) and aminocyclopyrachlor 

methyl ester (DPX-KJM44, referred to as the ester) are technical active ingredients, and these, 

along with aminocyclopyrachlor potassium salt (referred to as the salt), are formulated into 29 

different end-use products. These 29 product labels, which were submitted under DP368239 and 

DP358167, are included in this ecological risk assessment. 

Aminocyclopyrachlor is a systemic herbicide; it is biologically active in soil and rapidly 

absorbed by roots and leaves. It is then translocated through xylem and phloem until it reaches 

the meristematic plant regions where it mimics the plant hormone auxin. Upregulation of a set of 

proteins responsible for gene repression and the loss of tight control of the expression of a set of 

genes that maintain hormonal balance result in undifferentiated cell division and elongation; 

however, the changes in regulation of gene expression have not been thoroughly described. 

Effects to target weeds include epinasty (downward bending of leaves), severe necrosis, stem 

thickening, growth stunting, leaf crinkling, calloused stems and leaf veins, leaf-cupping, and 

enlarged roots. These symptoms may begin a few hours to a few days after application, and plant 

death may take weeks to several months. 

Aminocyclopyrachlor has been proposed for pre-emergent and post-emergent control of 

broadleaf weeds, woody species, vines, and grasses in uncultivated non-agricultural areas 

(airports, highway, railroad and utility rights-of-way, sewage disposal areas), uncultivated 

agricultural areas - non-crop producing (farmyards, fuel storage areas, fence rows, non-irrigation 

ditchbanks, barrier strips), industrial sites - outdoor (lumberyards, pipeline and tank farms), 

natural areas (wildlife management areas, wildlife openings, wildlife habitats, recreation areas, 

campgrounds, trailheads, and trails), and native grasses and turf grasses. Table 1.1 contains 

maximum proposed application rates, which were assessed in this document; see Table 3.1 for a 

complete rate table for all 29 proposed products. 

0.284 Ib a.e ./A 

Arninocyclopyrachlor WDG 

Acid 

NA = Not Applicable 

'WDG = water dispersible granule; SC = soluble concentrate; G = granule. 2 If not specified on label, number of applications may have been calculated based on maximum single application rate and 

maximum annual application rate. 

Turf Ground - G 0.108 Ib a.e./A 

(30 days) 3 0.324 Ib a.e ./A 
DuPont proposed a bridging strategy to relate the environmental fate and toxicity data @m one 

form to the other two forms of the chemical due to the ester hydrolyzing rapidly to the #cid and 

the salt dissociating rapidly to the acid. Therefore, most studies were submitted for the hcid only. 

In a few cases, studies were conducted with the ester to confirm equivalent toxicity or because it 

was a more appropriate product. No studies were submitted that evaluated the toxicity 

potassium salt. After review of the submitted data, EFED has determined that 

bridging strategy is not sufficient for evaluating toxicity to non-target 

a different strategy considering the nature of the chemical (see 

1.2 Potential Risks to Non-target Organisms I 

I 

A screening-level risk assessment based on proposed uses suggests that aminocyclopyr chlor 

presents potential risks to both non-listed and listed terrestrial plants and to organisms at 

depend on terrestrial plants for habitat and forage. Due to lack of acceptable avian repr duction 

and freshwater invertebrate life cycle toxicity data, chronic risks to non-listed and liste birds 

and freshwater and estuarinelmarine invertebrates are assumed. I I 

Several major degradates were identified to be of possible concern. Due to the lack of s bmitted 

toxicity data for the degradates, potential risks were described (see Section 5.2.3) using methods 

such as structure activity relationships (SARs), total toxic residue (TTR) approach, and 1 

comparisons of environmentally relevant concentrations to effects thresholds. From this 

EFED was able to reduce uncertainties regarding potential risks due to exposures to the 

degradates in the absence of toxicity data. 

Listed Species 

Based on available screening level information, for the proposed uses of aminocyclopyr chlor, 

there is a potential for direct effects to listed terrestrial plants. Due to lack of acceptable data for 

the acid, direct effects are assumed for birds (chronic) and freshwater invertebrates (chr I nic). 

Consequently, direct effects must be assumed for estuarinelmarine invertebrates (chroni ). 

Submittal of a chronic avian reproduction study and chronic freshwater invertebrate stu y would 

reduce the uncertainties associated with the presumed risk to these taxa. Based on risks o 

terrestrial plants and presumed chronic risk to freshwater invertebrates and birds, there i a 

potential concern for indirect effects to listed species via habitat perturbation andlor red ction in 

effects determinations is presented in Table 1.1. Because the proposed uses of 

the availability of forage or prey. In conducting a screen for indirect effects, direct effec I LOCs 

for each taxonomic group are used to make inferences concerning the potential for indir ct 

effects upon listed species that rely upon non-endangered organisms in these taxonomic groups 

as resources critical 'to their life cycle. A summary of the risk conclusions and direct and 1 indirect 

aminocyclopyrachlor cannot be geographically limited, all federally listed species may be either 

directly or indirectly affected. I 

Terrestrial and semi-aquatic Yes Yes plants - monocots 
Incidents 

Although no incidents have been reported for aminocyclopyrachlor because it is a new chemical, 

several incidents have been reported for a similar class of chemicals, the pyridine carboxylic 

acids. Incidents involving herbicides such as aminopyralid, picloram, and clopyralid were 

reported when treated plant residues or manure from animals fed treated residues were used in 

compost. The compost was then spread on areas where desirable crops or lawns were grown, and 

crop damage, which may have been caused by a pyridine carboxylic acid herbicide, was 

observed (see Section 4.4 for more details). Some states as well as the United Kingdom were 

prompted to take regulatory action because of these incidents. Because aminocyclopyrachlor also 

shares the persistent and systemic nature in soil and the high seedling emergence toxicity with 

these similar chemicals, similar incidents could occur following the application of 

aminocyclopyrachlor. 

1.3 Conclusions: Exposure Characterization 

Based on the registrant-submitted studies, the following conclusions were drawn regarding the 

environmental fate of aminocyclopyrachlor: 

Aminocyclopyrachlor is non-volatile (3.7 x rnm Hg and KH = 3.47 x 10-l2 atmm3/mol) and highly soluble (28 10 mgL at 20°C) in water. Based on the batch 

equilibrium data, aminocyclopyrachlor displays an affinity to organic carbon. Adsorption 

(KO, = 2 to 26 rnL/g,) is characterized as being highly mobile to mobile in the test soils. 
Therefore, dissipation of aminocyclopyrachlor in the environment is expected t$ occur 

predominantly from runoff and leaching. I 

The octanol/water partition coefficient (log K, of -2.48 at 20' at pH 7) for ; 

aminocyclopyrachlor suggests that it has a low tendency for bioaccumulation. ~ 

Considering biodegradation, aminocyclopyrachlor is persistent in aerobic aquat c and 

and anaerobic terrestrial environments. 

i aerobic terrestrial environments. In addition, it is relatively stable in anaerobic ~quatic 

I 

Considering abiotic degradation, aqueous photolysis is the major route of degra 

aminocyclopyrachlor is expected to degrade with a half-life of 1.2 days in 

and well-lit natural (pH 6.2) water bodies and 7.8 days in pH 4 buffer 

it is slowly photolyzed on soil (tlIz = 129 days). 

hydrolysis at pH 4,7, and 9. 

Dissipation occurred with half-lives ranging from 22 to 126 days in terrestrial fi 

dissipation studies conducted in the continental United States and Canada. i 

The major transformation products of aminocyclopyrachlor of concern at this ti 

IN-LXT69, IN-V0977 and IN-YY905.However, these degradates are not 

occur at environmentally relevant concentrations relative to effects thresholds. 1 

Conclusions regarding the environmental exposure concentrations for 

presented below: 

Aquatic EECs produced by GENEEC ranged from 16.64 ppb (60-day) to 

(peak) for aerial spray applications to non-crop areas for one application 

lb a.e./acre. EECs ranged from 16.26 ppb (60-day) to 16.47 ppb (peak) 

applications to non-crop areas for one application at a rate of 0.284 lb 

ground granular applications at a rate of three applications at 0.108 lb 

interval), EECs ranged from 16.60 ppb (60-day) to 16.82 ppb (peak). 

Considering the highest proposed application rate (one application at 0.284 lb a. ./acre), 

dietary-based exposure concentrations for terrestrial wildlife ranged from 4.26 t 68.16 

ppm. Avian and mammalian oral dose concentrations ranged from 0.28 to 77.63 glkgbw and 0.14 to 64.99 mglkg-bw, respectively. Terrestrial and semi-aquatic plant ECs 

ranged from 0 to 0.1562 ppm. \ I 

1.4 Conclusions: Effects Characterization I 

I 

Based on the registrant-submitted studies, the following conclusions were drawn regardi g the 

environmental effects of aminocyclopyrachlor: h 

Studies that evaluated the effects of the acid (DPX-MAT28) and the ester 

were submitted for aquatic flora and fauna. Toxicity classifications for 
ranged from practically non-toxic to slightly toxic. The acute freshwater fish and daphnid 

studies showed that the ester may be more toxic than the acid. No effects were observed 

in the chronic freshwater fish study, and a toxicity value could not be obtained from the 

chronic freshwater invertebrate study (see Section 4.1.2). 

For the most part, aminocyclopyrachlor was practically non-toxic to birds, mammals, and 

honey bees. As expected since aminocyclopyrachlor is an herbicide, toxicity based on 

seedling emergence and vegetative vigor endpoints were observed in the plant studies. 

1.5 Data Gaps 

No environmental fate data gaps were identified. 

Several environmental effects data gaps were identified (see Section 2.6.2). The following two 

studies are high priority studies because they have the potential to add value to the assessment by 

characterizing potential risks by eliminating uncertainties for both non-listed and listed species 

that cannot be accounted for using alternate methods or weights or evidence. 

Acid 

Avian Reproduction Toxicity Test (850.2300): Data are required for both an upland game 

and waterfowl species for the proposed use patterns. The submitted studies were 

classified as invalid due to improper husbandry practices (cage sizes that were much 

smaller than those recommended in the guideline) that may have caused incidental 

mortalities in quails and reduced egg production in mallards (see Section 4.2.1). Because 

of the lack of avian reproduction data, potential chronic risks to birds cannot be precluded 

for non-listed and listed species. 

Freshwater Invertebrate Life Cycle Toxicity Test (850.1300): Non dose-response 

mortalities were observed in the three lowest treatment levels (40%, 30%, and 40%, 

respectively) for the submitted freshwater daphnid study. Therefore, a NOAEC could not 

be established. Due to the high mortality observed in the first three treatment levels, the 

resulting toxicity values are not a reliable estimate of the chronic toxicity to water fleas 

(see Section 4.1.2 for details). 

2 Problem Formulation 

2.1 Nature of Regulatory Action 

The purpose of this assessment is to evaluate the environmental fate and ecological risks for the 

registration of the new chemical aminocyclopyrachlor. Aminocyclopyrachlor can be used pre- or 

post-emergently to control broadleaf weeds, woody species, vines, and certain grasses in nonagricultural areas, agricultural non-crop areas, industrial sites, natural areas, and in a residential 

and commercial setting for the protection of turf. As a new chemical, U.S. EPA is required under 

the Federal Insecticide Fungicide and Rodenticide Act (FIFRA) to ensure that 

aminocyclopyrachlor does not have the potential to cause unreasonable adverse effects to the 

environment. Potential effects to listed species (i.e., species on the Federal list of endangered 
and threatened wildlife and plants) are also considered under the Endangered Species Act in 

order to ensure that the registration of aminocyclopyrachlor is not l~kely to jeopardize 

continued existence of such listed species or adversely modify their habitat. To these e $e ds, this 

assessment follows U.S. EPA guidance on conducting ecological risk assessments (U.9 EPA, 

1998) and the Office of Pesticide Program's policies for assessing risk to non-target and listed 

organisms (U.S. EPA, 2004). I I 

Among the end products of the U.S. EPA pesticide registration process is a 

whether a product is eligible for registration and, if so, an enforceable 

product may be used. A label represents the legal document which 

given pesticide may be used. End-use labels describe the 

of application, where the product may be applied, and 

be conducted. Thus, the use, or potential use, 

"the action" being assessed. 

2.2 Stressor Source and Distribution I 

2.2.1 Nature of the Chemical Stressor I 

Aminocyclopyrachlor is a synthetic auxin and is the first member of a new class of chemistry 

called the pyrimidine carboxylic acids. This new class is similar to the pyridine carboxy ic acid 

class, which includes herbicides such as aminopyralid, clopyralid, and picloram. The ch mical's 

major route of degradation is aqueous photolysis. Aminocyclopyrachlor is stable to hyd olysis at 

pH 4 and 7. Arninocyclopyrachlor is expected to be highly mobile to mobile. It has low 1 olatility 

and is highly soluble in water. Therefore, dissipation of aminocyclopyrachlor from the ~ 

application site is expected to occur predominantly via aqueous photolysis, runoff, and 

Chemical characteristics of aminocyclopyrachlor and field dissipation studies suggest 

residues may leach into ground water. Additionally, off-site movement of 

is expected through spray drift from aerial and ground spray. A summary 

environmental fate data on arninocyclopyrachlor is provided in Table 2.1; more detaile 

descriptions of the submitted environmental fate data can be found in Section 3.2.1. 

Common Name 

Pesticide Class: 

EPA PC Code: 

IUPAC Name: 

Aminocyclopyrachlor 

synthetic auxin herbicide (pyrimidine carboxylic acid) 

288008 (acid), 288009 (ester), 288010 (salt) 

6-Amino-5-chloro-2-cyclopropyIpyrimidine-4- 

carboxylic acid 

-- 

I 

-- I 

~ 

I 

-- ! 

I 

~ -- i 

I 
CAS Name(s): 

CAS No: 

Formula: 

Structure: 

Molecular Mass (glmol) 

Vapor pressure (torr) at 25' 

C 

Henry's Law Constant at 

20' C (atm m3/mol) 

Solubility in Water (mg/L) 

at 20 OC 

Octanol- Water Partition 

Coefficient (Log KO, ) at 

20 OC 

Dissociation Constant pKa 

at 20°C 

6-Amino-5-chloro-2-cyclopropyl-4- 

pyrimidinecarboxylic acid 

6-Amino-5-chloro-2-cyclopropyl-pyrimidine-4- 

carboxylic acid 

858956-08-8 

CsH8C1N302 

28 10 in Milli-Q water 

3130 atpH4 

4200 at pH 7 

3870 at pH 9 
2.2.2 Mode of Action I 

According to the registrant, aminocyclopyrachlor is a systemic herbicide; it is biologicz+lly active 

in soil and rapidly absorbed by roots and leaves. It is then translocated through xylem and 

phloem until it reaches the meristematic plant regions where it mimics the plant homo e auxin. 

Upregulation of a set of proteins responsible for gene repression and the loss of tight co trol of 

the expression of a set of genes that maintain hormonal balance result in undifferentiate cell 

division and elongation; however, the changes in regulation of gene expression have no 1 been 

thoroughly described. Effects to target weeds include epinasty, severe necrosis, stem th ckening, 

growth stunting, leaf crinkling, calloused stems and leaf veins, leaf-cupping, and enlarg roots. 

These symptoms may begin a few hours to a few days after application and death may t e 

weeks to several months. 

2.2.3 Environmental Fate and Effects Bridging Strategy 

i 

There are three proposed forms of aminocyclopyrachlor: (1) an acid, (2) a methyl ester, and (3) a 

potassium salt. The registrant did not submit a full suite of required studies for each fo of the 

chemical. Instead, the registrant submitted mostly full suites of environmental fate and i ffects 

studies for the acid form of aminocyclopyrachlor, limited data were submitted for the m thy1 i; ester, and only a dissociation study was submitted for the potassium salt. All fate and I 

toxicological values were converted to the acid equivalent (a.e.) based on the ratio of molecular 

weights. This was done for ease of comparing fate parameters and toxicity values acros the 

various forms of aminocyclopyrachlor. It was determined, based on the submitted study that the 

potassium salt dissociates to the acid rapidly prior to application (when mixed with wat r as the 

two salt formulation labels state) and that the methyl ester hydrolyzes to the acid in the 

summarized in Tables 3.2,3.3, and 3.4. 

I 

environment (Figure 1). Available environmental fate data submitted by the registrant 

Figure 1. Schematic of Bridging Strategy of Aminocyclopyrachlor Methyl Ester an 

Aminocyclopyrachlor Potassium Salt to Aminocyclopyrachlor Acid 

I 

ACP Potassium Salt + dissociation in water 3 ACP Acid + Potassium Cation (K') 1 

I 

ACP Methyl Ester +' microbial-mediated hydrolysis + ACP Acid + Alcohol (methanol 

alkaline-catalyzed hydrolysis 

To assess the dissociation of the potassium 

dissociation constant (MRID 478909-01). 

was previously determined to be 4.65. The dissociation constant of the 

4.63 when conducting measurements within 2 to 7 minutes after the 

to the test system. This study supports the rapid conversion of the 

base of the acid and the potassium cation. This similarity in 

behavior of aminocyclopyrachlor acid and 
Therefore, environmental fate and toxicity data submitted on the acid is also relevant for the 

potassium salt for the currently proposed uses; if different formulations of the salt are proposed 

in the future where the salt would be released to the environment rather than dissociating to the 

acid prior to application (for instance, a granular salt formulation), a full suite of salt toxicity data 

may be necessary. 

The submitted laboratory and terrestrial field dissipation data indicate the arninocyclopyrachlor 

methyl ester is hydrolyzed in alkaline aquatic environments, moist soils, and soillwater slurries. 

Degradation under environmentally relevant pH conditions is primarily microbe-mediated. 

Therefore, use of the methyl ester end-use products of aminocyclopyrachlor may result in shortterm exposures to the methyl ester form of arninocyclopyrachlor. However, the methyl ester is 

expected to degrade to the acid form of aminocyclopyrachlor rapidly under most environmental 

conditions. 

The de-esterification of arninocyclopyrachlor methyl ester is more difficult to generalize because 

it is dependent on heterogeneous hydrolysis (microbe-mediated) and homogeneous hydrolysis 

(abiotic alkaline catalyzed (Schwarzenbach et al., 1993). The de-esterification of 

arninocyclopyrachlor methyl ester leads to the formation of the arninocyclopyrachlor acid and 

the associated alcohol, methanol. Unlike the physical dissociation mechanism of the 

arninocyclopyrachlor potassium salt, the de-esterification of aminocyclopyrachlor methyl ester is 

dependent on abiotic and microbe-mediated processes. Any environmental variable influencing 

microbe populations or activity could theoretically influence the persistence of 

aminocyclopyrachlor methyl ester. Soil properties including clay mineralogy, organic carbon 

content, temperature, and moisture content are known to influence hydrolysis rates (Wolfe et al., 

1989 and Wolfe, 1990). 

Registrant-sponsored research indicates that arninocyclopyrachlor methyl ester degrades to form 

the acid. In the hydrolysis study (MRID 478357-Ol), the calculated half-lives at 20°C for pH 4, 

7 and 9 were 27, 52 and 0.3 days, respectively. This data suggests alkaline-catalyzed abiotic 

hydrolysis. Since the hydrolysis study is conducted in a sterile (abiotic) environment, an aerobic 

soil metabolism (MRID 475602-14) and a batch equilibrium (MRID 475602-18) study were 

investigated. In the aerobic soil metabolism study, the half-life could not be accurately calculated 

because of the rapid transformation to the arninocyclopyrachlor acid in acidic soil (pH = 5.4). In 

the batch equilibrium studies, rapid degradation of the test substance was also observed in acidic 

and alkaline soils. The weight of evidence from the aerobic soil metabolism and batch 

equilibrium (biotic) studies suggest a microbe-mediated hydrolytic process at lower pHs. 

Only two aquatic studies were submitted for the ester (see Section 4). The submitted data did not 

confirm equivalent toxicity; the freshwater fish toxicity value was about an order of magnitude 

more toxic for the ester than the acid and the freshwater invertebrate toxicity value was about 

twice as toxic for the ester than the acid. Although acute terrestrial toxicity (based on submitted 

toxicity data) and chronic terrestrial and chronic aquatic toxicity (based on submitted fate data) 

for the ester is suspected to be equivalent to the acid, other aquatic taxa may be exposed to the 

ester on an acute basis. 
2.3 Overview of Pesticide Usage , 

Aminocyclopyrachlor has been proposed for gre-emergent and post-emergent control of 

broadleaf weeds, woody species, vines, and g~rasses in uncultivated non-agricultural are'hs 

(airports, highway, railroad and utility rights-of-way, sewage disposal areas), 

agricultural areas - non-crop producing (farmyards, fuel storage 

ditchbanks, barrier strips), industrial sites - outdoor (lumberyards, pipeline 

natural areas (wildlife management areas, wildlife openings, wildlife 

campgrounds, trailheads, and trails), and native grasses and turf 

are found throughout the United States and cannot be limited to 

aminocyclopyrachlor is a new chemical, use data does not yet exist. 

2.4 Receptors 

2.4.1 Aquatic and Terrestrial Effects ! 

The receptor is the biological entity that is exposed to the stressor (U.S. EPA, 1998). C 

with the process described in the Overview Document (U.S. EPA, 2004), this risk 

uses a surrogate species approach in its evaluation of aminocyclopyrachlor. 

generated from surrogate test species, which are intended to be 

taxonomic groups, are used to extrapolate to potential effects on a variety 

included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along 

available open literature are used to evaluate the potential direct effects of 

to the aquatic and terrestrial receptors identified in this section. This 

technical grade active ingredient, degradates, and when available, 

"Six-Pack" studies). The open literature studies are identified 

available ECOTOX database (http://cfpub.epa.~ov/ecotox/), 

engine for locating chemical toxicity data for aquatic life, 

evaluation of both sources of data can also provide 

aminocyclopyrachlor on biotic communities from loss of species that are sensitive to th 

chemical and from changes in structure and functional characteristics of the affected 

communities. ~ 

2.4.2 Ecosystems Potentially at Risk I 

I 

Aquatic ecosystems potentially at risk include water bodies adjacent to, or down stream 

treated field and might include impounded bodlies such as ponds, lakes and reservoirs, o 

The ecosystems at risk are often extensive in scope; as a result, it may not be possible to1 

specific ecosystems during the development of a baseline risk assessment. However, in 

terms, terrestrial ecosystems potentially at risk could include the treated field and areas 

immediately adjacent to the treated field that may receive drift or runoff. Areas adjacent 

treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow 

grasslands, woodlands, riparian habitats and other uncultivated areas. 

identify 

general 

to the 

fields or 
waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also includes 

marine ecosystems, including estuaries. 

2.4.3 Ecological Effects 

Each assessment endpoint requires one or more "measures of ecological effect," which are 

defined as changes in the attributes of an assessment endpoint itself or changes in a surrogate 

entity or attribute in response to exposure to a pesticide. Ecological measurement endpoints for 

this risk assessment would be based on toxicity information for aminocyclopyrachlor in the 

publicly available ECOTOX database (if available) and a suite of registrant-submitted toxicity 

studies performed on a limited number of organisms in the following broad groupings: 

1. Birds (mallard duck or bobwhite quail and a passerine species), also used as a surrogate 

for terrestrial-phase amphibians and reptiles 

2. Mammals (laboratory rat) 

3. Freshwater fish (rainbow trout and bluegill sunfish), also used as a surrogate for aquaticphase amphibians 

4. Freshwater invertebrates (daphnid) 

5. Estuarinelmarine fish (sheepshead minnow) 

6. Estuarinelmarine invertebrates (Eastern oyster, mysid shrimp) 

7. Terrestrial plants (monocots and dicots) 

8. Aquatic plants (vascular and non-vascular plants) 

9. Terrestrial invertebrates (honeybee) 

Within each of these very broad taxonomic groups, an acute and chronic endpoint is selected 

from the available test data, as the data allow. 

2.5 Conceptual Model 

A conceptual model provides a written description and visual representation of the predicted 

relationships between aminocyclopyrachlor, potential routes of exposure, and the predicted 

effects for the assessment endpoint. A conceptual model consists of two major components: risk 

hypotheses and a conceptual diagram (U.S. EPA, 1998). 

2.5.1 Risk Hypotheses 

Terrestrial and aquatic organisms are subject to adverse direct effects such as reduced 

survival, growth, and fecundity or indirect effects such as habitat, food web dynamics, 

perturbing forage or prey availability, and altering the extent and nature of nesting when 

exposed to aminocyclopyrachlor/degradate residues as a result of labeled use of the pesticide. 

Non-target terrestrial, semi-aquatic, and aquatic plants are subject to adverse effects such as 

reductions in vegetative vigor and seedling emergence (terrestrial) or biomass and growth 

rate (aquatic) when exposed to aminocyclopyrachlor/degradate residues as a result of labeled 

use of the pesticide 
2.5.2 Conceptual Diagram I 

In order for a 

biologically significant 

contaminant moves in the environment from a source to an ecological 

exposure pathway to be complete, it must have a source, a release 

transport medium, a point of exposure for ecological receptors, 

In addition, the potential mechanisms of transformation (i.e., 

environment, in which media, and how much) must be 

metabolitesldegradates 

exposure pathways, 

pathways for constituents, and the 

inhalation, and dermal absorption). 

Figure 2. Conceptual model depicting ecological risk based on proposed aminocyclopyrachlor appl cations. 

Dotted boxes indicated pathways not considered in the risk assessment. i 

Based on the labels submitted by the registrant, the source and mechanisms of release fo 

aminocyclopyrachlor are aerial andlor ground application in the form of soluble concent 1 ates and 

water dispersible granules (for non-crop uses and some professional turf uses) or ground^ 

application as a granule (with a fertilizer for all residential and most professional turf us4s). The 

I 

Stressor I Aminocyclopyrachlor Applied Aerially and by Ground I 

+ + 4 4 I 

I------------ 

Source1 Volatilization/ : Ground Spray Drift Runoff1 Leaching I 

I 

Transport Wind : Deposition Erosion (Infiltration/ 1 

pathway I Suspension Percolation) I - - - - , -, -- , -- + 

Source/ 

Exposure 

Media 

4- 

Ground 

water 

Terrestrial 

Food Residues 

(foliage, fruit, 

insects)/ Soil - 

I 

Direct ContacV Root Uptake Method Uptake 

Receptors Terrestrial Animals Terrestrial 

B~rds, Mammals, Upland Plants Riparian Plants 

Reptiles, Terrestrial- - Plants 

phase Amphibians, Bees 

+ 

Direct 

Effects: 

NonEndangered 

species 

Upland 

Foliage/ 

Soil 

Individual Terrestrial Individual Terrestrial Individual A uatic 

Animals plants Vertebrates and 

Reduced Sunrival Seedling Emergence Reduced Invertebrates 

Growth Rates Reduced Survival 

Reduced Growth Vegetative Vigor and Biomass Reduced Growth 

Reduced Reproduction - Reduced Reproduction 

Bioaccumulation 

Indirect Perturbing Forage or Prey Availability I 

Effects 1 

Habitat Alteration: impacting nesting ability, ability to I 

I 

I 

Riparian1 

Wetland 

Foliage/Soil 

Surface 

Water, 

Sediment 
conceptual model and subsequent analysis of exposure and effects are all based both on the 

parent and degradates (where data are available) of aminocyclopyrachlor. Potential emission of 

volatile compounds is not considered as a viable release mechanism for arninocyclopyrachlor, 

because Henry's Law constant (3.47 x 10-l2 atm-m3/mol) suggests that volatilization is not 

expected to be a significant route of dissipation for this chemical (indicated by dashed lines in 

the diagram). Aminocyclopyrachlor concentrations in surface waters may be relatively high 

when significant runoff events occur after application andlor spray drift to water bodies in close 

proximity to the treatment area occurs. Aminocyclopyrachlor has the potential to leach to ground 

water, which can serve as inputs to surface water. The conceptual model shown in Figure 2 

generically depicts the potential source of arninocyclopyrachlor, release mechanisms, abiotic 

receiving media, and biological receptor types. 

2.6 Analysis Plan 

This assessment characterizes the environmental fate and effects of arninocyclopyrachlor and 

determines whether there is potential for risks to non-target organisms based on the proposed use 

patterns. Available environmental fate, ecotoxicity, and physicochemical property data were 

taken from submitted studies to the Agency. The environmental fate and effects studies 

underwent reviews to determine their acceptability relative to published U.S. EPA guidelines. 

The maximum proposed label application rates for the use of arninocyclopyrachlor on non-crop 

areas and turf were selected for modeling environmental concentrations for this base-level 

deterministic (risk-quotient based) assessment. The most sensitive toxicity endpoints from 

surrogate test species are used to estimate treatment-related effects on survival, growth, and 

reproduction. Estimated environmental concentrations (EECs) used in terrestrial and aquatic 

ecological risk assessments are based on the parent aminocyclopyrachlor compound. Because 

toxicity data has not been submitted for any of the degradates, EECs were not calculated for any 

degradates; however the total toxic residue approach was used to describe potential risks. For the 

aquatic assessment, EECs are initially produced by GENEEC. If LOC exceedances were to occur 

when comparing EECs to the toxicity values, PRZMIEXAMS would then be used to refine 

exposure estimates. For the terrestrial assessment, EECs are produced by T-REX and TerrPlant. 

To evaluate the spatial extent of risk to non-target terrestrial plants, AgDRIFT is used to 

determine at what distance from the application area LOCs are no longer exceeded. 

The following sections characterize the use, environmental fate, and ecological effects of 

aminocyclopyrachlor and use the risk quotient (ratio of EEC to toxicity value) approach to 

estimate the potential for adverse effects on non-target terrestrial and aquatic organisms. This 

risk quotient-based approach does not provide a quantitative estimate of likelihood and/or 

magnitude of an adverse effect. Such estimates may be possible through a more refined, 

probabilistic assessment; however, they are beyond the scope of this base-level assessment. 

2.6.1 Measures of Effect and Exposure 

Table 2.2 lists the measures of environmental exposure and ecological effects used to assess the 

potential risks of arninocyclopyrachlor to non-target organisms (U.S. EPA, 2004). 
Table 2.2. Measures of Environmental Exposure and Ecological Effects Used to Assess the 

Potential Risks of Aminocyclopyrachlor to Non-target Organisms 

Assessment Endpoint 1 Measures of Effect I Measures of Exposure 

1 Abundance (i. e., survival, IBobwhite quail/ mallard duck acute oral LDS0( I 

reproduction, and growth) of 

individuals and populations of birds 

Abundance (i.e., survival, 

reproduction, and growth) of 

individuals and populations of 

mammals 

Abundance (i. e., survival, 

reproduction, and growth) of 

individuals and communities of 

freshwater fish 

Abundance (i. e., survival, 

reproduction, and growth) of 

individuals and communities of 

freshwater invertebrates 

Bobwhite quail/ mallard duck sub-acute 

dietary LCs0 

Bobwhite quail/ mallard duck chronic 

reproduction NOAEC and LOAEC 

Laboratory rat acute oral LD50 

Laboratory rat Zgeneration NOAEC and 

LOAEC 

Rainbow trout and bluegill sunfish LCs0 

Rainbow trout and/or bluegill sunfish 

NOAEC and LOAEC 

Abundance (i. e., survival, 

reproduction, and growth) of 

individuals and communities of 

estuarinelmarine fish and 

invertebrates 

2.6.2 Data Gaps 

No environmental fate data gaps were identified. 

I 

Maximum residu s on food 

items (fol'ar) 1 

I 

I 

I 

Peak EE~ 

I 

I 

60-day averagk EEC 

I 

I 

Daphnid ECsO 

Daphnid life cycle NOAEC and LOAEC 

Survival of beneficial insect 

populations and natural Lepidoptera 

predators 

Maintenance and growth of 

individuals and populations of 

terrestrial plants from standing crop 

or biomass 

Maintenance and growth of 

individuals and populations of aquatic 

plants from standing crop or biomass 

I 

Peak EE$ 

2 1-day averagq EEC 

I 

Sheepshead minnow acute LCs0 

Eastern oyster ECS0 

Mysid shrimp LCs0 

Sheepshead minnow NOAEC and LOAEC 

Mysid shrimp NOAEC and LOAEC 

Honeybee acute contact LDSo 

Monocot ECZ5 and NOAEC values for 

seedling emergence and vegetative vigor 

(survival and growth rate) 

Dicot ECZ5 and NOAEC values for seedling 

emergence and vegetative vigor (survival and 

growth rate) 

Vascular plant (i. e., Lemna) ECS0 and 

NOAEC values for growth rate and biomass 

measurements 

Non-vascular plant (i. e., green algae) ECSo 

and NOAEC values for growth rate and 

biomass measurements 

I 

I 

Peak EE~ 

60-day averagq 

- 

Single Maximum 

application 

EEC 

rate 

2 1 -day averam EEC 

Estimates of run0 and spray 

drift to non-targ t areas 1 

I 

, 

Peak EEC( 

I 
Data gaps for environmental effects were assigned a low or high priority based on their potential 

to add value to the ecological risk assessment. While still considered data gaps according to 40 

CFR Part 158, low priority studies are unllkely to change risk determinations because alternate 

methods and weights of evidence (i.e., acute-to-chronic ratio, scaling factors, or consideration of 

environmentally relevant concentrations relative to effects thresholds) can be used in the absence 

of data. High priority studies are needed to characterize potential risks by eliminating 

uncertainties for both non-listed and listed species that cannot be accounted for using alternate 

methods or weights of evidence. It is important to note that a study that is currently assigned a 

low priority based on its potential to add value could be changed to high priority based on future 

proposed uses, submitted data, and/or incidents. 

The following environmental effects data gaps were identified: 

Acid 

Avian Acute Oral Toxicity Test (850.2100): Data are required for one passerine species 

and either one waterfowl species or one upland game bird species for terrestrial, aquatic, 

forestry, and residential outdoor uses. The current method of calculating a weightadjusted LDso using bobwhite quail or mallard duck data may over- or under-estimate 

risks to passerines because these birds may metabolize the chemical differently. Because 

the 850.2100 guideline has not yet been finalized, protocols for the study of passerine 

species should be submitted to EPA for approval prior to study initiation. This study has a 

low priority based on its potential to add value to the ecological risk assessment. 

Avian Reproduction Toxicity Test (850.2300): Data are required for both an upland game 

and waterfowl species for the proposed use patterns. The submitted studies were 

classified as invalid due to improper husbandry practices (cage sizes that were much 

smaller than those recommended in the guideline) that may have caused incidental 

mortalities in quails and reduced egg production in mallards (see Section 4.2.1). Because 

of the lack of avian reproduction data, potential chronic risks to birds cannot be precluded 

for non-listed and listed species. This study has a high priority based on its potential to 

add value to the ecological risk assessment. 

EstuarineIMarine Fish Early-life Stage Toxicity Test (850.1400): The proposed use 

patterns indicate that aminocyclopyrachlor may enter estuarinelmarine environments. The 

acute-to-chronic ratio cannot be used to predict potential chronic risks to estuarinelrnarine 

fish because there were no definitive acute or chronic values for the acid. In addition, the 

acute estuarinelmarine fish study produced a non-definitive LC50. This study has a low 

priority based on its potential to add value to the ecological risk assessment. 

Freshwater Invertebrate Life Cycle Toxicity Test (850.1300): Non dose-response 

mortalities were observed in the three lowest treatment levels (40%, 30%, and 40%, 

respectively) for the submitted freshwater daphnid study. Therefore, a NOAEC could not 

be established. Due to the high mortality observed in the first three treatment levels, the 

resulting toxicity values are not a reliable estimate of the chronic toxicity to water fleas 
(see Section 4.1.2 for details). This study has a high priority based on its potential to add 

value to the ecological risk assessment. 

EstuarineMarine Invertebrate Life Cycle Toxicity Test (850.1350): The propos$d use 

patterns indicate that aminocyclopyrachlor may enter estuarinelmarine 

Due to the lack of a definitive chronic NOAEC in freshwater 

chronic ratio cannot be used to predict potential chronic risks to estuarinelmarin 

invertebrates. This study has a low priority based on its 

ecological risk assessment. 

Ester i 

EstuarineMarine Fish Acute Toxicity Test (850.1075). This study has a low pri&rity 

based on its potential to add value to the ecological risk assessment. I 

I 

EstuarineMarine Mollusk Acute Toxicity Test (850.1025). This study has a low priority 

based on its potential to add value to the ecological risk assessment. 1 

EstuarineJMarine Invertebrate Acute Toxicity Test (850.1035). This study has a fow 

priority based on its potential to add value to the ecological risk assessment. 

Aquatic Plant Toxicity Test (850.4400). This study has a low priority based on i s 

potential to add value to the ecological risk assessment. 

t I 

Algal Toxicity Test (850.5400). This study has a low priority based on its potent a1 to add 

value to the ecological risk assessment. f 

I 

Salt I 

The two proposed salt formulations specify mixing with water prior to 

is expected to cause the salt to dissociate to the acid in which case the 

to be released into the environment. Therefore, salt studies are not requested at 

However, if future uses enable the salt to be applied to the environment (such 

granular salt formulation), a full suite of acute and chronic toxicity data may 

adequately assess potential risks. These studies are currently in reserved status. 

I 

Degradates I 

ECOSAR was used to predict aquatic toxicity of the degradates since no data weke 

submitted. The results of this modeling indicated that there are two potential deg adates 

of concern for aquatic organisms (see Section 5.2.3). Freshwater invertebrates m y be 

chronically exposed to IN-LXT69 and IN-YY905. Because reliable SARs do not exist for 

terrestrial ecotoxicity estimation, EFED defers to HED's SAR evaluation in the sence 

of degradate toxicity data (D370368, October 15, 2009). HED determined that I -V0977 

(cyclopropanecarboxylic acid) may be more toxic than the parent to mammals. I -V0977 

has the potential to form in aquatic environments through aqueous photolysis an i may be 
more mobile than the parent. Acute and chronic exposures to birds and mammals are 

possible. However, to determine the potential to add value to a risk assessment, the total 

toxic residue and comparisons of EECs to the effects thresholds approaches were used to 

assign a priority for the receipt of additional studies. 

For IN-LXT69 and IN-YY905: 

o Freshwater Invertebrate Life Cycle Toxicity Test (850.1300). This study has a 

low priority based on its potential to add value to the ecological risk assessment. 

For IN-V0977: 

o Avian Acute Oral Toxicity Test (850.2100). This study has a low priority based 

on its potential to add value to the ecological risk assessment. 

o Avian Acute Dietary Toxicity Test (850.2200). This study has a low priority 

based on its potential to add value to the ecological risk assessment. 

o Avian Reproduction Toxicity Test (850.2300). This study has a low priority based 

on its potential to add value to the ecological risk assessment. 

o Mammalian Acute Oral Toxicity Test (870.1100). This study has a low priority 

based on its potential to add value to the ecological risk assessment. 

o Mammalian Oral Two Generation Reproduction Toxicity Test (870.3800). This 

study has a low priority based on its potential to add value to the ecological risk 

assessment. 

3 Exposure Analysis 

3.1 Use Characterization 

Aminocyclopyrachlor, a systemic herbicide that is the first member within the new pyrimidine 

carboxylic acid class of chemistry, is proposed for registration under FIFRA. 

Aminocyclopyrachlor acid (DPX-MAT28) and aminocyclopyrachlor methyl ester (DPXKJM44) are the two technical active ingredients; the acid is also formulated into' 

aminocyclopyrachlor potassium salt. Due to the observed rapid hydrolysis of the methyl ester in 

environmental systems and dissociation of the potassium salt to the acid in tank mixtures, it is 

appropriate to bridge data for the salt to the acid and terrestrial and chronic aquatic data for the 

ester to the acid (see Section 2.2.3). However, it is possible, based on the submitted data, that 

aquatic organisms could be exposed to the ester on an acute basis. Because of the possibility of 

acute exposure combined with the submitted data showing that the ester is more acutely toxic to 

aquatic organisms than the acid, acute aquatic toxicity data for the ester is not bridged to the 

acid. 
According to the proposed labels, aminocyclopyrachlor may be used against a variety f 

registration for non-crop and turf uses. 

broadleaf weeds, woody species, vines, and tall grasses. The registrant is seeking initia; 0 

i 

For non-crop use, aminocyclopyrachlor is a dispersible granule that is mixed in water 

be applied by aerial or ground application methods for pre- or post-emergence for 

broadleaf weeds and grass species. A single application of 0.284 lb a.e./acre can 

yearly maximum application rate of 0.284 lb a.e./acre. 

For residential or commercial turf use, aminocyclopyrachlor is applied with a fertiliz 

granule that allows selective pre- or post-emergent broadleaf weed control in cool se 

certain warm season turf grasses on lawns (residential, industrial, and institutional), 

parks, cemeteries, athletic fields, and sod fields. Commercial turf uses can also be 

spray as soluble concentrate and water-dispersible granule formulations are propo 

registration. Aminocyclopyrachlor may control every major broadleaf weed, som 

include dandelion, clover, plantains, wild violet and ground ivy. Aminocyclopyr 

applied only by ground application methods for turf uses. Three applications of 0.108 

a.e./acre can be applied with a 30-day application interval for a yearly maximu 

of 0.324 lb a.e./acre (commercial use rate). , 

Table 3.1 summarizes the proposed application rates and methods for 29 end-use produ ts. Four 

products also contain other active ingredients (sulfometuron, chlorsulfuron, metsulfuro 4 and 

imazapyr); however, this assessment only addresses potential risks due to exposure to 

aminocyclopyrachlor. Table 3.1 does not include the technical labels or the 

concentrate labels (352-TIG, 352-TIE, 352-TOA, 352-TOL, 352-TIU). 

contains sulfometuron 

and chlorsulfuron) 
GroundIAerial 

and imazapyr) 

DuPontTM DPX-Q2B39 

Herbicide (Also 

contains metsulfuron) 

DuPontTM DPX-QKJ02 

Herbicide (Also 

contains chlorsulfuron) 

352-TON 

(ester) 

352-TOR 

(ester) 

53.6 

53.6 

0.094 

0.094 

0.094 

0.108 

0.100 

0.096 

0.108 

0.100 

0.090 

3 

(14 days) 

3 

(14 days) 

3 

(14 days) 

3 

(30 days) 

3 

(30 days) 

3 

(30 days) 

3 

(30 days) 

3 

(30 days) 

3 

(30 days) 

GroundAerial 

- WDG 

GroundAerial 

- WDG 

0.282 

0.282 

0.282 

0.324 

0.300 

0.288 

0.324 

0.300 

0.270 

Turf: Professional Use 

DuPontTM DPX-KJM44 

80XP Turf Herbicide 

DUPontTM DPXMAT28 240SL Turf 

Herbicide 

DUPontTM DPXMAT28 50SG Turf 

Herbicide 

DuPontTM DPX-KJM44 

0.064G Turf Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.053G Turf Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.032G Turf Herbicide 

+ Fertilizer 

DuPontTM DPXMAT28 0.06G Turf 

Herbicide + Fertilizer 

DuPontTM DPXMAT28 0.05G Turf 

Herbicide + Fertilizer 

DuPontTM DPXMAT28 0.03G Turf 

Herbicide + Fertilizer 

Turf: Consumer Use 

75 

* 

50 

0.06 

0.05 

0.03 

0.06 

o.05 

o.03 

Products 

352-TOE 

(ester) 

352-TOG 

(salt) 

352-T0U 

(acid) 

352-~0~ 

(ester) 

352-~01 

(ester) 

352-~00 

, (ester) 

352-1RE 

(acid) 

352-IRG 

(acid) 

352-IRU 

(acid) 

Products 

0.268 

0.268 

Ground - WDG 

Ground - SC 

Ground - WDG 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

0.068 Ground - G 0.075 

DuPontTM DPXMAT28 0.068G Lawn 

Herbicide + Fertilizer 

1 

1 

2 

(42 days) 

352-1RL 

(acid) 

0.268 

0.268 

0.150 
Table 3.1. Proposed Application Rates for 29 Products Containing Aminocyclopyracblor 

DuPontTM DPX-KJM44 

0.073G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.065G Lawn Herbicide 

- + Fertilizer 

maximum annual application rate. 

- - -- 

DuPontTM DPX-KJM44 

0.059G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.053G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-lWVf# 

0.049G Lawn 

Herbicide + Fertilizer 

DuPontTM DPX-KJM44 

0.039G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.037G Lawn 

Herbicide u Fertilizer 

DuPontTM DPX-KJM44 

0.033G Lawn 

Herbicide + Fertilizer 

DuPontTM DPX-KJM44 

0.03G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.027G Lawn 

Herbicide + Fertilizer 

DuPontTM DPX-KJM44 

0.024G Lawn Herbicide 

+ Fertilizer 

DuPontTM DPX-KJM44 

0.02G Lawn Herbicide 

+ Fertilizer 

'WDG = water dispersible 

Maximum Singk 

Application Rate 

(Ib a.eJacre) 

Product 

352-INN 

(ester) 

352-INR 

(ester) 

% 

a.e. 

EPA File 

(a.i. form) 

'1f not specified on label, number of applications may have been calculated based on maximum single applicatibn rate and 

352-1NE 

(ester> 

352-ING 

(ester) 

352-IpJU 

(ester) 

352-JNL 

(ester> 

352-IN* 

(ester) 

352-INT 

(ester) 

352-INI 

(ester) 

352-m0 

(ester) 

352-IRN 

(ester) 

352-IRR 

(ester) 

granule; SC 

Application ' 

'~omuiation 

TY pe' 

Maximum 

Number of 

~~~licationsl~ea? 

(Application 

Interval) 

0.069 

0.061 

Maximum 

Application 

Ob a.eJacre) 

0.055 

0.05 

0.046 

0.037 

0.035 

0.03 1 

0.028 

0.025 

0.023 

0.01 8 

= soluble 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

Ground - G 

concentrate; G = 

0.075 

0.075 

0.075 

0.075 

0.050 

0.050 

0.038 

0.038 

0.038 

0.038 

0.025 

0.025 

granule. 

2 1 

(42 days) 1 

2 

(42 days) 

0.150 

0.150 

2 

(42 days) 

2 

(42 days) 

2 

(42 days) 

2 

(42 days) 

2 

(42 days) 

0.150 

0.150 

0.100 

0.100 

0.076 

2 

(42 days) I 0.076 

2 

(42 days) I 

I 

0.076 

2 

(42 days) 

1, 

0.076 

2 1 (42 days) , 

I 

0.050 

2 

(42 days) 1 0.050 

I 
3.2 Exposure Assessment 

3.2.1 Environmental Fate and Transport Characterization 

Environmental fate properties for aminocyclopyrachlor acid (DPX-MAT28) and the end-use 

products aminocyclopyrachlor methyl ester (DPX-KJM44) and aminocyclopyrachlor potassium 

salt are listed separately in Tables 3.2,3.3, and 3.4, respectively. 

Aminocyclopyrachlor's major route of degradation is aqueous photolysis. The compound is 

expected to degrade with a half-life of 1.2 days in natural (pH 6.2) water and 7.8 days in pH 4 

buffer solution. Aminocyclopyrachlor is stable to hydrolysis at pH 4,7, and 9. 

Aminocyclopyrachlor is expected to be highly mobile to mobile. It is non-volatile (4.9 x 10'~ Pa. 

at 25°C; 3.7 x low8 mm H~; MRID 475598-18 with KH = 3.47 x 10-l2 atm-m3/mol; MRID 

475598-20) and highly soluble (2810 mg/L at 20°C; MRID 475598-16) in water. Therefore, 

dissipation of aminocyclopyrachlor from the application site is expected to occur predominantly 

via aqueous photolysis, runoff, and leaching. Arninocyclopyrachlor was detected at soil depths 

of 70 - 90 cm at 365 days (MRID 475751-02), which indicates that leaching of residues into 

ground water may occur. Additionally, off-site movement of aminocyclopyrachlor is expected 

through spray drift from aerial and ground spray. 

Hydrolysis 

[161-11 

Aqueous Photolysis 

[161-21 

pH 4: t 112 = stable @ 50°C 

pH 7: t = stable @ 50°C 

pH 9: t 112 = stable @ 50°C 

Observed DTsO > 5 days 

pH 4 buffer: 

t = 7.8 days @ 20°C 

Observed DTsO - 168 days 

Natural Water (pH = 6.2): 

t = 1.4 days @ 20°C 

Observed DTsO - 29 days 

Transformation products: 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylamine (IN-LXT69) - 

maximum 16.1 % of the applied found only in pH 4 buffer. 

Degradate found increasing over time. 

2. 4-Cyano-2-cyclopropy1-1H-imidazole-5-carboxylic acid (INQFH57) - maximum 13.8% of the applied in pH 4 buffer. 

Degradate found increasing over time. Maximum 33.1% of the 

applied in natural water (pH = 6.2). 

3. Cyclopropanecarboxylic acid (IN-V0977) - maximum 12.4% of the 

applied in pH 4 buffer. Maximum 14.6% of the applied in natural 

water (pH = 6.2). Degradate increasing over time especially in 

natural water. 

475602- 10 

475602- 1 1 
Soil Photolysis 

[161-31 

Aerobic Aquatic 

Metabolism 

[162-41 

Anaerobic Aquatic 

Metabolism 

[162-31 

the applied in pH 4 buffer. Maximum 1 1.7% of the applied in 

natural water (pH = 6.2). Degradate increasing over time in both 

~ 

systems. 1 

I 

t = 129 days @ 20°C 1 

Observed DT50 > 15 days ~ 

Transformation products:: 1 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylamie (IN-LXT69) - 

maximum 4.9% of the applied found at 7 days (15 day study 

' 

duration). 

2. Non-extractable Residues - maximum 17.2% of the applied found at 

15 days (15 day study duration). 

Sand-Water: 

Observed DT50 > 100 days (W, S, TS) ' 

Silt-loam-Water: 

Observed DT50 > 100 days (W, S, TS) 

Transformation products: 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylamine (IN-LXT69) - For 

Sand-Water: maximum 2.3% in water fraction, 1.0% in sediment 

fraction, 2.3% in total system. For Silt-Loam-Water: maximum 

2.4% in water fraction, 1.2% in sediment fraction, 2.4% in total 

system. Note: Analysis of the test substance standard showed a 

small amount of IN-LXT69; therefore, it appears likely that the 

maximum percent of applied dose at Day 0 is a contaminant and not 

a transformation product. 

2. Carbon Dioxide: - For Sand-Water: maximum 0.70% of the 

applied at 100 days (100 day study duration). For Silt-Loam-Water: 

maximum 0.20% of the applied at 100 days (100 day study 

duration). COz increasing throughout study. 

3. Non-Extractables - For Sand-Water: maximum 6.5% of the applied 

at 100 days (100 day study duration). For Silt-Loam-Water: 

maximum 11.1 % of the applied at 100 days (100 day study 

duration). COP increasing throughout study. 

ppp~~p pp~~ 

Total System: 

t = 1733 days (stable) 

Observed DTS0 > 120 days 

Observed DT50 > 365 days (W ,S, TS) 

Transformation products: 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylamine (IN-LXT69) - 

475602-13 

475602- 16 

I 

I 

~ 

I 475602-17 

I 

I 

i 
applied at 100 days (100 day study duration). For Silt-Loam-Water: 

maximum 0.20% of the applied at 100 days (100 day study 

duration). C02 increasing throughout study. 

3. Non-Extractables: maximum 17.1 % of the applied at 180 days (365 

Observed DTS0 - 3 10 days 

Transformation products: 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylami (IN-LXT69) - For 

Sassafras soil, maximum 2.9% of the applied at 3 days (260 day 

Aerobic Soil Metabolism 

[162-11 

2. Carbon Dioxide: - For Sassafras soil: maximum 23.1 % of the 

applied at 360 days (360 day study duration). C02 increasing 

throughout study. 

3. Non-Extractables: - For Sassafras soil: maximum 24.4% of the 

applied at 300 days (360 day study duration). 

Nambsheim: 

t = 433 days (non-linear) 

Observed DTS0 > 120 days 

Tama: 

t = 114 days 

Observed DTS0 - 110 days 

Drummer: 

t = 126 days 

Observed DT50 - 110 days 

Transformation products: 

1. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylami (IN-LXT69) - For 

Nambsheim soil, maximum 4.0% of the applied at 0 days (120 day 

study duration). For Tama soil, maximum 4.2% of the applied at 0 

days (120 day study duration). For Drummer soil, maximum 6.4% 

of the applied at 0 days (120 day study duration). 

2. Non-Extractables: For Nambsheim soil, maximum 13.0% of the 

applied at 120 days (120 day study duration). For Tama soil, 

maximum 43.2% of the applied at 120 days (120 day study 

duration). For Drummer soil, maximum 39.3% of the applied at 120 

days (120 day study duration). Sorption increasing throughout 

study. 

475602-2 1 
Anaerobic Soil 

t = 6932 days (stable) 

Soil type: Drummer Clay Loam 

Adsorption Kd: 0:98 

Adsorption K,: 26 

Freundlich adsorption Kfoc: 24.8 

Desorption Constants: Not Determined 

Soil type: California Loam 

Adsorption Kd: 0.03 

Adsorption KO,: 5.2 

Organic Carbon (%) = 0.5 

Adsorption1 

Desorption 

(% and 

KO, in L K~-') 

[163-11 

Freundlich adsorption Kf: 0.004 

Freundlich adsorption Kfo,: 0.8 

lln: 0.5167 

Desorption Constants: Not Determined 

Soil type: Nambsheim Sandy Loam 

Adsorption Kd: 0.03 

Adsorption &: 2.0 

Organic Carbon (%) = 1.3 

Clay (%) = 7 

Freundlich adsorption Kf: 0.016 

Freundlich adsorption Kfoc: 1.2 

1111: 0.0871 

Desorption Constants: Not Determined 

Soil type: Lleida Silty Clay 

Adsorption &: 0.05 

Adsorption KO,: 3.2 

Organic Carbon (%) = 1.6 

Clay (%) = 45 

Freundlich adsorption Kf: 0.066 

Freundlich adsorption Kf,: 4.1 

lln: 1.046 

Desorption Constants: Not Determined 

Soil type: Sassafras #16 Sandy Loam 

Adsorption Kd: 0.27 

Adsorption KO,: 22 . 

Organic Carbon (%) = 1.2 

Clay (%) = 13 

I 

~ 

~ 

i 

I I 

i 

1 

i 

1 

I 

I 

1 

I 

I ! 

I 

1 

I 

i 

I 

I 

I 

1 

I 

I 
Canada Bare Soil: 0-5 em. 

Dissipation t = 126 days 

California Bare Soil: 

Terrestrial Field 

Dissipation 

[164-11 

'W = Water; S = Sediment, TS = Total System (sum of concentrations in water and sediment extracts) 

Possible leacher - detected at 70-90 cm. 

No major transformation products detected. 

Georgia turf: Grass 

Dissipation t = 22.4 days 

Observed DT50 - 4.3 days 

0-5 em: 

Dissipation t = 27 days 

Observed DTS0 - 10.8 days 

Possible leacher - detected at 15-30 cm. 

Canada turf: Grass. 

Dissipation t = 24.2 days 

Observed DT50 - 5.4 days 

0-5 em: 

Dissipation t = 38 days 

Observed DTSo - 21 days 

Possible leacher - detected at 50-70 cm. 

Transformation product detected: 5-Chloro-2-cyclopropyl-pyrimidin-4- 

ylamine (IN-LXT69) 

Canada turf: Grass. 

Dissipation t 112 = 7.2 days 

Observed DT50 - 3.3 days 

475602-22 

475602-23 
Hydrolysis 

[161-11 

Aerobic Soil Metabolism 

[162-11 

Terrestrial Field 

Dissipation 

[164-11 

t, = 26.9 days @ 40°C at pH 4 

t% = 51.7 days @ 20°C at pH 7 

k = 0.3 days @ 20°C at pH 9 

pH 4 buffer: 

t = 4.1 days 

Observed DT50 > 2 days 

Degradates: 

1. 6-Amino-5-chloro-2-cyclopropylpyrimidine-4-cboxylic acid 

(parent aminocyclopyrachlor) - maximum 3.3% of the applied at 8 

hours (2 day study duration). 

2. 5-Chloro-2-cyclopropyl-pyrimidin-4-ylamine (IN-LXT69) - 

maximum 9.3% of the applied at 2 days (2 day study duration). 

3. Cyclopropanecarboxamide (IN-Q3007) - maximum 7.8% of the 

applied at 2 days (2 day study duration). 

Half-life could not be accurately calculated because of the rapid 

transformation to the aminocyclopyrachlor acid (< 1% of the applied 

remaining after 3 days). 

Canada Bare Soil: 0-5 cm 

Dissipation t = 7.7 days 

Observed DTqn - 4.6 days 

CA Bare Soil: 0-5 cm. 

Dissipation t = 3.8 days 

Observed DTS0 - 1.2 days 

GA turf: Grass. 

Dissipation t 112 = 1.3 days 

Observed DTso - 1 day 

0-5 cm: 

Dissipation t = 5.5 days 

Observed DT50 - 1 day 

Canada turf: Grass. 

Dissipation t = 5.6 days 

Observed DT50 - 1 day 

0-5 cm: 

Dissipation t = 48 days 

Observed DT50 - 1 day ' 
Mobility 

Based on the batch equilibrium data, aminocyclopyrachlor displays an affinity to organic carbon. 

Adsorption of aminocyclopyrachlor (Kc = 2 to 26 mL/g,,, MRID 475602-19) is characterized as 

being highly mobile to mobile in the test soils (FA0 Classification; U.S. EPA, 2006). Desorption 

constants were not provided. However, 13 - 39% of non-extractable residues were found in an 

aerobic soil metabolism study (MRID 475602-21). Sufficient extraction methods were used and 

sorption increased throughout the study. 

Aminocyclopyrachlor is non-volatile (4.9 x lod Pa. at 25°C; 3.7 x mm Hg; MRID 475598- 

18 and KH = 3.47 x atm-m3/mol; MRID 475598-20) and highly soluble (2810 mg/L at 

20°C; MRID 475598-16) in water. Therefore, dissipation of aminocyclopyrachlor is expected to 

occur predominantly via runoff and leaching. Aminocyclopyrachlor was detected at soil depths 

of 70 - 90 cm at 365 days (MRID: 475751-02), which indicates that leaching of residues into 

ground water may occur. 

Degradation 

Considering biodegradation, arninocyclopyrachlor is persistent in aerobic aquatic (tllz not 

determined; observed DTso > 100 days; MRID 475602-16) and aerobic terrestrial environments 

(tIl2 = 315 days; MRID 475602-14). In addition, it is relatively stable in anaerobic aquatic (tln = 

1733 days; MRID 475602-17) and anaerobic terrestrial environments (tia = 6932 days; MRID 

47560215). 

Considering abiotic degradation, aqueous photolysis (MRID 475602-1 1) is the major route of 

degradation and aminocyclopyrachlor is expected to degrade with a half-life of 1.2 days in 

shallow, clear, and well-lit natural (pH 6.2) water bodies and 7.8 days in pH 4 buffer solution. 

However, it is slowly photolyzed on soil (tllz = 129 days; MRID 475602-13). 

Aminocyclopyrachlor is stable to hydrolysis (MRID 475602-10) at pH 4,7, and 9. 

Dissipation occurred with half-lives ranging from 22 to 126 days in terrestrial field dissipation 

studies conducted in the continental United States and Canada (MRID 475751-02,475602-22, 

475602-23, and 475602-24). 
Degradates of Concern I 1 

The major environmental degradates of aminocyclopyrachlor include IN-LXT69, IN-Q H57, 

IN-Q3007, IN-V0977, IN-YY905, C02 and an unidentified aqueous photoproduct (Ta ," le 3.5). 

Most of the major degradates formed under aqueous photolysis and were increasing in mount at 

study termination. Ecological risks were quantified for the parent arninocyclopyrachlor acid only 

due to lack of toxicity data for the degradates. ECOSAR was used to predict toxicity of the 

degradates to aquatic organisms (see Section 5.2.3), and because of the lack of submitt d 

toxicity data, the total toxic residue (TTR) approach was explored. However, EECs we e not 

calculated for degradates IN-LXT69 and IN-YY905 because the major degradation pro ess of 

aminocyclopyrachlor (aqueous photolysis) was not a significant component of residue 

target organisms due to exposure to the degradates can be qualitatively described. 

i 

calculation in GENEEC (see Section 5.2.3). Structure activity relationships (SARs) we e also 

used to predict the toxicity of the degradates to terrestrial organisms to determine what oxicity 

data is required for a comprehensive assessment. Using these approaches, potential risk to non- I 
3.2.2 Aquatic Exposure Estimates for Aminocyclopyrachlor 

(unidentified) 

A Tier I screening-level surface water exposure for aquatic risk assessment was conducted for 

the Section 3 proposed new chemical registration. Modeled application rates represent the 

maximum use patterns of the proposed labels for non-crop and turf use. Pre- and post-emergent 

spray applications (aerial and ground spray for non-crop areas; ground spray only for turf) and 

granular applications (ground only for turf) are proposed (see Table 3.1). The aquatic exposure 

estimates presented in this assessment were based on the use of models as no surface and ground 

water monitoring data is available for aminocyclopyrachlor within the continental U.S. To 

simulate surface water exposure for the ecological risk assessment, the Tier I GENEEC2 model 

was used. 

GENEEC2 Model Inputs for Aminocyclopyrachlor 

(unidentified) 

The GENEEC (GENeric Estimated Environmental Concentration) model, a Tier I computer 

program, uses the soillwater partition coefficient and degradation kinetic data to estimate runoff 

from a ten hectare field into a one hectare by two meter deep "standard" pond. This first tier is 

designed as a coarse screen and estimates conservative pesticide concentrations in surface water 

from a few basic chemical parameters and pesticide label use and application information. Tier I 

is used to screen chemicals to determine which ones potentially pose sufficient risk to warrant 

higher level modeling. 

GENEEC is a program to calculate acute as well as longer-term estimated environmental 

concentration (EEC) values. It considers reduction in dissolved pesticide concentration due to 

adsorption of pesticide to soil or sediment, incorporation, degradation in soil before washoff to a 

water body, direct deposition of spray drift into the water body, and degradation of the pesticide 

within the water body. It is designed to mimic a high-end PRZM-EXAMS simulation. Additional 

16.8 Aqueous Photolysis 

MRID 475602- 1 1 
information on this and other models can be found at: 

http://www.epa.g;ov/oppefed1/models/water/index.htm. 

The aquatic exposure is estimated for the maximum application pattern to a 10-ha field 

a 1-ha pond, 2-m deep (20,000 m3) with no outlet. Exposure estimates generated using 

standard pond are intended to represent a wide variety of vulnerable water bodies that ( 

the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, n 

and natural ponds, and intermittent and first-order streams. As a group, there are factor 

make these water bodies more or less vulnerable than the standard surrogate pond. Stat 

bodies that have larger ratios of pesticide-treated drainage area to water body volume v 

expected to have higher peak EECs than the standard pond. These water bodies will be 

smaller in size or have large drainage areas. Smaller water bodies have limited storage 

and thus may overflow and carry pesticide in the discharge, whereas the standard pond 

discharge. As watershed size increases beyond 10-ha, it becomes increasingly unlikelj 

entire watershed is planted with a non-major single crop that is all treated simultaneou: 

the pesticide. Headwater streams can also have peak concentrations higher than the stai 

pond, but they likely persist for only short periods of time and are then carried and diss 

downstream. 

Table 3.6 summarizes the model input parameter values used in GENEEC2 to estimatc 

aminocyclopyrachlor concentrations in aquatic systems for ecological risk assessment. 

'I' 

3( 

i 

S 

:I( 

c 

I' 

$1 

nt 

i. 

bordering 

his 

;cur at 

m-made 

that 

2 water 

auld be 

:ither 

apacity 

ias no 

that the 

y with 

dard 

pated 

Method of Application 

spray zonelbuffer (non-crop - parent) 

Incorporation Depth (inches) Broadcast Application - 
MIUD 475602- 16 

MRID 475602-1 1 

The estimated environmental concentrations (EECs) for the parent aminocyclopyrachlor acid for 

non-crop and turf use are listed in Table 3.7. In general, aerial applications resulted in higher 

EECs compared to ground applications. Maximum concentrations are highlighted in bold. The 

GENEEC output files are listed in Appendix A. 

1 app @ 0.284 a.e./acre 

Aquatic Exposure Monitoring and Field Data 

Since aminocyclopyrachlor is a new active ingredient, no national-scale monitoring data were 

available for this chemical. 
3.2.3 Terrestrial Wildlife Exposures I 

I 

Terrestrial wildlife exposure estimates are typically calculated for birds and mammals 

emphasizing a dietary exposure route for uptake of pesticide residues on vegetative mat'er and 

insects. Birds are used as surrogates for terrestrial-phase amphibians as well as reptiles. JFor 

exposure to terrestrial organisms, pesticide residues on food items are estimated based 

assumption that organisms are exposed to a single pesticide residue in a given 

The residue estimates from spray applications are based on a nomogram by 

(1972) as modified by Fletcher et al. (1994) that correlated residue levels, 

rate, on various terrestrial items immediately following application in the 

residue concentration, an upper bound defined by Fletcher et al. (1994), 

derived from literature and tolerance data. 

Dissipation of aminocyclopyrachlor residues on food items following single and 

applications is predicted using a first-order residue degradation half-life with 

v1.4.1 model. T-REX assumes a default foliar dissipation half-life estimate 

and McDowell, 1987). This half-life is used in lieu of aminocyclopyrachlor 

data, which were not submitted by the registrant. The maximum predicted 

mammalian food items (dietary EECs) as a result of applications to 

in Table 3.8 and 3.9. Application to non-crop areas, according to 

chosen because it represents the scenario with the highest 

maximum annual application rates. Although 

proposed granular application rates are lower 

reason, the ~~~o/ft~ approach was not used. 

The residues or EECs on food items may be compared directly with sub-acute dietary 

data or converted to an ingested whole-body dose (single oral dose). Single oral dose 

represent, for many pesticides, an exposure 

maximized over a single ingestion event. Sub-acute dietary estimates provide for 

of the dietary matrix and more extended 

gut. However, dietary exposure endpoints 

ingestion estimates are uncertain and may not be directly 

to field conditions. The EEC is converted to an oral dose by multiplying the EEC by the 

percentage of body weight consumed as estimated 

consumption-weighted EECs (i. e., EEC equivalent 

and body size for birds (20, 100, and 1000 

equivalent doses for birds and mammals 

given in Tables 3.8 and 3.9, respectively. Example output from T-REX is included in 

Appendix B. 

As predicted by HED (see Section 5.2.3), the degradate IN-V0977 (cyclopropanecarbox 

acid) may pose additional risks to birds and mammals. However, because toxicity data h 

been submitted, EECs were not calculated. 
3.2.4 Terrestrial and Semi-Aquatic Plant Exposures 

Broadleaf plants/small insects 

Fruits/pods/seeds/large insects 

Granivores 

Terrestrial and semi-aquatic plants may be exposed to pesticides from runoff, spray drift, or 

volatilization. Semi-aquatic plants are those that inhabit low-lying wet areas that may be dry at 

certain times of the year. The runoff scenario in TerrPlant v1.2.2 is: (1) based on a pesticide's 

water solubility and the amount of pesticide present on the soil surface and its top one 

centimeter, (2) characterized as "sheet runoff" (one treated acre to an adjacent acre) for dry areas, 

(3) characterized as "channel runoff" (10 acres to a distant low-lying acre) for semi-aquatic or 

wetland areas, and (4) based on runoff values of 1,2, and 5% for water solubility values of <lo, 

10-100, and >I00 ppm, respectively. Spray drift is assumed as (1) 1% for ground application, (2) 

5% for aerial, airblast, forced air, and spray chemigation applications, and (3) 0% for granular 

applications. Currently, EFED derives plant exposure concentrations from a single maximum 

application rate only. Exposure through volatilization is not accounted for in this baseline 

assessment; however, based on the low vapor pressure, it is not expected to be a significant route 

of exposure. EECs for turf and non-crop areas are presented in Table 3.10. Example of TerrPlant 

output is provided in Appendix C. 

38.34 

4.26 

Table 3.10. EECs for Terrestrial and Semi-aquatic Plants for Aerial and/or Ground 

Application ----- to Turf and Non-crop Areas 

36.55 

4.06 

0.90 

Runoff to dry areas 

IhrF 

(0.108 Ib a.ehcre) 

Ground 

Description (granule) 

25.26 

2.81 

0.62 

Turf 

(0.094 Ib a.e./acre) 

Ground 

(spray) 

Noa-crop Areas 

(0.284 Ib a.eJacre) 

0.0054 

5.86 

0.65 

0.14 

Ground 

(spray) 

Aerial 

(spray 

0.0047 0.0142 0.0142 
4 Ecological Effects Analysis I 

A search of the public ECOTOX database (http://cfpub.epa.~ov/ecotox) on October 30,2009 did 

not yield any aquatic or terrestrial open literature studies for aminocyclopyrachlor. This result is 

to be expected as aminocyclopyrachlor is a new chemical. Therefore, only studies subrrjitted by 

the registrant were evaluated to determine the effects of aminocyclopyrachlor on non-t get 

organisms. The Ecological Incident Information System (EIIS) was also reviewed to pr "$ vide a 

refined characterization of the ecological effects. As expected, no incidents were found 

aminocyclopyrachlor; however, several incidents were found involving the pyridine 

acids (see Section 4.4). 

Runoff to semi-aquatic areas 

Spray drift 

Total for dry areas 

Total for semi-aquatic areas 

I 4.1 Aquatic Effects Summary ~ 

0.054 

0 

0.0054 

0.054 

0.047 

0.00094 

0.00564 

0.04794 

Studies that evaluated the effects of the acid (DPX-MAT28) and the effects of the ester DPXKJM44) were submitted for aquatic flora and fauna. Toxicity classifications for those st i dies 

requiring them ranged from practically non-toxic to slightly toxic. The acute freshwater (fish and 

daphnid studies showed that the ester may be more toxic than the acid. Because the subbitted 

data on the ester were limited, there are some uncertainties regarding the toxicity of the 

Section 4.3). 

4.1.1 Toxicity Effects on Fish i 

0.142 

0.00284 

0.01704 

0.14484 

Two definitive studies that evaluated the acute effects of the acid to rainbow trout (MRQ 

475601-23) and bluegill sunfish (MRID 475601-24) were submitted. Measured test 

concentrations ranged from 7.6 to 122 mg a.e./L for the rainbow trout and 7.5 to 120 m a.e./L 

for the bluegill sunfish. There was a complete lack of mortality and sublethal effects in 0th of 

the studies; both studies classify aminocyclopyrachlor as practically non-toxic and satis y the 

guideline requirements for an acute freshwater fish study. The rainbow trout 96-hr LCsO was 

>I22 mg a.e./L and the NOAEC was 122 mg a.e./L. The bluegill sunfish 96-hr LCso wa >I20 

mg a.e./L and the NOAEC was 120 mg a.e./L. A definitive study that evaluated the acut effects 

of the ester to rainbow trout (MRID 475602-06) was submitted. The 96-hr LCsO was 13 g a.e./L 

and the NOAEC was 8.1 mg a.e./L. Lethargy was the sublethal effect observed in the t o highest 

test concentrations. Based on these results, the ester would be classified as slightly toxic to 

freshwater fish. The guideline requirements are satisfied by this study. Results of the thr e acute 

freshwater fish studies are summarized in Table 4.1. 1 

(3.142 

0.0142 

C .0284 

C.1562 
A limit test study was submitted that evaluated the acute effects of the acid to an 

estuarine/marine fish, sheepshead minnow (MRID 475601-25). There was a complete lack of 

mortality and sublethal effects; the 96-hr LCso and 96-hr ECso were >I29 mg a.e./L and the 

NOAEC was 129 mg a.e./L. The results of the study classify the acid as practically non-toxic to 

estuarinelmarine fish. Guideline requirements for an acute study on estuarine/marine fish are 

satisfied. Results of this study are summarized in Table 4.2. 

A 90-day chronic toxicity test was submitted that evaluated the effects of the acid on the earlylife stage of rainbow trout (MRID 475601-30) under flow-through conditions. Measured test 

concentrations were between 0.69 and 11 mg a.e./L. There were no treatment-related effects on 

hatching success, time to hatch, post-hatch survival, time to swim-up, or growth at any treatment 

level. The 90-day LC/EC50 for all endpoints was >11 mg a.e./L, and the NOAEC and LOAEC 

were 11 and >11 mg a.e./L, respectively. This study satisfies the guideline requirement for an 

early-life stage study with freshwater fish. The results are summarized in Table 4.3. 

4.1.2 Toxicity Effects on Invertebrates 

"Denotes value used for RQ calculation. 

Practically 

Non-toxic 

Slightly 

Toxic 

96-hr LC50: >I20 mg a.e./L 

NOAEC: 120 mg a.e./L 

(no effects) 

96-hr LC50: 13 mg a.e./L* 

NOAEC: 8.1 mg a.e./L 

(based on mortality and 

sublethal effects [lethargy]) 

850.1075 

acid 

(92.2%) 

850.1075 

ester 

(90.9% a.e.) 

A study was submitted that evaluated the acute effects of the acid on water fleas (MRID 475601- 

26). Measured test concentrations were between 3.7 and 120 mg a.e./L. The 48-hour LCso was 

39.7 mg a.e./L. Sublethal effects were observed in all but the lowest test concentration; the 48-hr 

NOAEC based on mortality and sublethal effects (lethargy) was 3.7 mg a.e./L. Based on these 

results, the acid is classified as slightly toxic to freshwater invertebrates. This study satisfies the 

guideline requirements for an acute toxicity study with freshwater invertebrates. A study was 

Bluegill sunfish 

(Lepomis 

macrochirus) 

Rainbow trout 

(Oncorhynchus 

mykiss) 

Acceptable 

Acceptable 

475601-24 

475602-06 
also submitted that evaluated the acute effects of the ester on water fleas (MRID 47560L-07). 

Measured test concentrations were between 0.92 and 30 mg a.e./L. The 48-hour LCso das 19.9 

mg a.e./L. Sublethal effects were seen at all but the lowest test concentration; the 48-hrlNOAEC 

based on mortality and sublethal effects (lethargy and surfacing) was 0.92 mg a.e.1L. ~$ese 

results classify the ester as slightly toxic to freshwater invertebrates. This study satisfie$ the 

guideline requirements for an acute toxicity study with freshwater invertebrates. The re 

these two studies are summarized in Table 4.4. 

NOAEC: 0.92 mg a.e./L 

(based on mortality and 

sublethal effects [lethargy and 

Two studies were submitted that evaluated the effects of the acid on estuarinelmarine 

invertebrates. An oyster shell deposition test using the Eastern oyster (MRID 

produced an ICso of >I18 mg a.e./L. 

observed in the highest test concentration; the NOAEC was 67 mg a.e./L. 

the acid as practically non-toxic to estuarinelrnarine mollusks, and the 

requirements. A mysid shrimp acute toxicity test (MRID 4752601-28) 

that was >I22 mg a.e./L. Because there were no significant 

NOAEC for this study was 122 mg a.e./L. The acid is 

estuarinelmarine invertebrates. Guideline 

these two studies are summarized in 

A 21-day chronic toxicity study was submitted that evaluated the effects of the acid on 

fleas (MRID 475601-29) under static renewal conditions. Measured test concentrations 

between 0.37 and 6.0 mg a.e./L. The 21-day LC5() for adult mortality was >6.0 mg a.e./L 

However, non dose-response mortalities were observed in the 0.37,0.73, and 1.5 mg 

acid (Crassostrea 96-hr ECS0: >I18 mg a.e./L Acceptable 47560 1-27 

(92.2%) 

850.1035 

acid 

(92.2%) 

virginica) 

Mysid shrimp 

(Americamysis 

bahia) 

NOAEC: 67 mg a.e./L 

96-hr LCa: >I22 mg a.e./L 

NOAEC: 122 mg a.e./L 

(no effects) 

Non-toxic 

Practically 

Non-toxic Acceptable 4752601 -28 
40%, 30, and 40%, respectively. Therefore, a NOAEC could not be established. This study is 

scientifically sound but is classified as supplemental. Due to the high mortality observed in the 

first three treatment levels, the resulting toxicity values do not provide a reliable estimate of the 

chronic toxicity to water fleas. Additionally, immobility was observed in all treatment levels of 

the second range-finding test; however, data for the range-finding tests were not provided. 

Finally, in the acute water flea study (MRID 475601-26), sublethal effects and mortality 

provided a NOAEC of 3.7 mg a.e./L; this comparison suggests a possible issue with the health of 

the test organisms in this chronic study. The results of this study are summarized in Table 4.6. 

4.1.3 Toxicity Effects on Plants 

Four studies were submitted that evaluated the effects of the acid on non-vascular plants. A 96- 

hour study was done with freshwater blue-green algae (MRID 475602-01). Cell density, growth 

rate, and biomass were the endpoints affected with biomass being the most sensitive. The 

NOAEC and ECso values for biomass were 1.1 1 and 7.4 mg a.e.L, respectively. There were no 

differences in cell morphology between the control and treatment groups, but flocculation and 

aggregation of cells was observed in all treatment levels but the highest. A 96-hour study was 

done with the marine diatom (MRID 475602-02). There were extremely low or no inhibitions for 

all endpoints, which resulted in a NOAEC and EC50 value of 120 and >I20 mg a.e./L, 

respectively. There were no differences in cell morphology between the control and treatment 

groups, and flocculation, aggregation, and adherence were not observed in any group. A 72-hour 

study was conducted for freshwater green algae (MRID 475602-03). No endpoint was inhibited 

by more than 50%; therefore, the EC50 value was determined to be >I20 mg a.e.L. The cell 

density and biomass endpoints shared NOAEC and ECo5 values of 15.3 and 62 mg a.e./L. There 

were no differences in cell morphology between the control and treatment groups, and 

flocculation, aggregation, and adherence did not occur in any group. A 96-hour study was 

conducted on freshwater diatom (MRID 475602-04), and high inhibitions (96-99%) were 

reported for all three endpoints. Biomass was the most sensitive endpoint with an EC50 of 38 mg 

a.e./L and a NOAEC of 14 mg a.e./L. There were no differences in cell morphology between the 

control and the treatment groups. There was no evidence of flocculation, aggregation, or 

adherence in any group. Guideline requirements are satisfied by all four studies (freshwater 

green algae study satisfies Tier I requirements only), and they are summarized in Table 4.7. 
A 7-day study was submitted that evaluated the effects of the acid on a 

(MRID 475601-34). None of the endpoints were inhibited by more than 50%; 

values for frond number, frond number yield, biomass, and growth rate based on frond 

were >I22 mg a.e./L. Frond number and frond number yield were the most sensitive 

with ECo5 values of 21 mg a.e./L with NOAEC values of 3.75 mg a.e./L. By test 

there were isolated cases of chlorosis, necrosis, and dead fronds observed in all 

test level. In the highest test level, some or all of the fronds were small, curled, 

all of the colonies were coagulating (not breaking apart).This study satisfies guideline 

requirements for a freshwater vascular plant toxicity test and is summarized in 

850.5400 

acid 

(92.2%) 

850.5400 (Tier I) 

acid 

(92.2%) 

850.5400 

acid 

(92.2%) 

4.2 Terrestrial Effects Summary 

Marine diatom 

(Skeletonema costatum) 

Green algae 

(Pseudokirchneriella 

subcapitata) 

Freshwater diatom 

(Navicula pelliculosa) 

850.4400 

acid 

(92.2%) 

Thirteen studies were submitted that evaluated the effects of arninocyclopyrachlor to teriestrial 

non-target organisms. The plant studies were conducted using a technical end-use produ t (TEP), 

which was an ester formulation. Similarly, one of the avian acute oral studies and one o the 

mammalian acute oral studies were conducted using the ester. For the most part, 

f I 

arninocyclopyrachlor was practically non-toxic to birds, mammals, and invertebrates. A{ 

expected since arninocyclopyrachlor is an herbicide, seedling emergence and vegetative vigor 

toxicity was affected in the plant studies. ~ 

4.2.1 Toxicity Effects on Birds I 

96 hr EC50: >I20 mg a.e./L 

NOAEC: 120 mg a.e./L 

(no effects) 

72 hr ECSo: >I20 mg a.e./L 

72 hr ECo5: 62 mg a.e./L 

NOAEC: 15.3 mg a.e./L 

(cell density and biomass) 

96 hr ECS0: 38 mg a.e./L 

NOAEC: 14 mg a.e./L 

(biomass) 

Duckweed (Lemna gibba) 

Two acute oral toxicity studies were submitted for bobwhite quail. The study with the adid 

(MRID 475601-18) showed a complete lack of mortality and sublethal effects. There weke no 

signs of toxicity, effects on body weight, or changes in food consumption between the c$ntrol 

and treatment groups. The 14-day LDsO was >2075 mg a.e./kg-bw, and the NOAEL was PO75 mg 

1 a.e./kg-bw. The study classifies the acid as practically non-toxic and satisfies guideline 1 

requirements for an acute oral toxicity test for an upland game bird or waterfowl speciesi The 

study with the ester (MRID 475602-05) did not show any mortality. There were no dinikal signs 

I 

Acceptabl& 

Acceptabl? 

Acceptabl? 

7-day EC5O: >I22 mg a.e./L 

7-day ECo5: 21 mg a.e./L 

NOAEC: 3.75 mg a.e./L 

(frond number and frond number 

yield) 

475602-02 

475602-03 

475602-04 

~cce~table 475601 -34 
of toxicity, effects on food consumption, or change in female body weight; however, there was a 

significant change in male body weight in the three highest treatment groups. The 14-day LD50 

was >2045 mg a.e./kg-bw, and the NOAEL was 442 mg a.e./kg-bw. This study classifies the 

ester as practically non-toxic, and guideline requirements are satisfied by this study. 

Acute dietary toxicity studies were submitted for each of the bobwhite quail and mallard duck. 

For the 10-day-old bobwhite quail (MRID 475601-20) and the 10-day-old mallard duck (MRID 

475601-19), both studies showed a complete lack of mortality and sublethal effects. There were 

no signs of toxicity, effects on body weight, or changes in food consumption between the control 

and treatment groups. For both studies, the 8-day LCso was >5290 mg a.e./kg-diet, and the 

NOAEC was 5290 mg a.e./kg-diet. These results classify the acid as practically non-toxic to 

juvenile bobwhite quails and mallard ducks. 

The four avian acute toxicity studies are summarized in Table 4.9. 

Chronic dietary reproduction toxicity studies with the acid were submitted for each of the 

bobwhite quail (MRID 475601-21) and mallard duck (MRID 475601-22). In the quail study, 

cages were approximately six times smaller than recommended in the guideline. Seven incidental 

mortalities occurred in the control and all three treatment groups. It is possible that the small 

cage size contributed to these mortalities as external injuries, including bruising, fractures, and 

necrotic lesions, were observed. Therefore, the improper husbandry practices used in the study 

may have affected reproductive endpoints in both the control and treatment groups. The study is 

classified as invalid and does not satisfy guideline requirements. In the mallard study, cages were 

approximately three times smaller than recommended in the guideline. Three incidental 

mortalities were observed in the control and the two lower treatment groups. It is possible that 

cage size may have affected the reproductive endpoints measured in this study in all treatment 

levels, including the controls. Additionally, sixteen hens in the control and treatment groups were 

observed to be non-productive (less than ten eggs laid). Necropsy showed that egg yolk 

peritonitis was apparent in the non-laying hens. Although this endpoint may not be treatmentrelated, the health of the birds is questionable. This study is classified as invalid and does not 

satisfy guideline requirements. 
4.2.2 Toxicity Effects on Mammals , 

An acute oral acid toxicity study on the rat was conducted using the up-and-down procedure 

(MRID 475599-34). Three female rats were dosed with 5000 mg a.e./kg-bw (acid, 92.2 o purity) 

and observed for fourteen days. The day after dosing, one rat had diarrhea but recovere by the 

next day. There were no mortalities or clinical signs of toxicity at the end of the test; ne ropsies 

did not show any gross lesions. The LD50 was determined to be >5000 mg a.e.kg-bw, 

study was classified as acceptable. 

id the 

I 

An acute oral ester toxicity study on the rat was conducting using the up-and-down pro 

(MRID 475600-27). Six female rats were dosed with 175,550, 1750, or 5000 mg 

(ester, 96.9% purity) by gavage (three rats were dosed at the 5000 mgkg-bw 

observed for fourteen days. One rat at the'5000 mg a.e./kg-bw treatment 

on the day of dosing and hair loss (forelimbs) on days 13 and 14. 

and gained weight during the study. The other animals had no 

mg a.e./kg-bw, and the study was classified as acceptable. 

treatment related gross lesions were noted at necropsy. The 

In a two-generation reproduction toxicity study (MRID 475751-Ol), 28 ratslsexldose 

exposed to the acid (90.9-92.2% purity) at dietary levels of 0,500, 1500,5000, or 17, 

(equivalent to 010,36141, 1091125,3631416, and 128511454 mg a.e.kg-bwlday in ma 

during pre-mating) for two successive generations with one litter per generation. No 

related effects were observed on mortality, clinical signs, or macroscopic or microscopi 

findings. The LOAEC for parental toxicity was 17,000 ppm (equivalent to 12851145 

maleslfemales), based on decreased body weights in parental males and females. Th 

was 5000 ppm (equivalent to 3631416 mag in maleslfemales). The LOAEC for offsp 

toxicity was 17,000 ppm (equivalent to 128511454 mglkg in rnaleslfemales), based o 

body weights in the F1 and F2 pups. The NOAEC was 5000 ppm (equivalent to 363141 mag 

in rnaleslfemales). The LOAEC for reproductive toxicity was not observed. The NOAE was 

17,000 ppm (equivalent to 128511454 mglkg in maleslfemales). This study was classifie as 

acceptable. I I 

Results of the three mammalian toxicity studies are summarized in Table 4.10. 1 
4.2.3 Toxicity Effects on Invertebrates 

An acute earthworm toxicity test with the ester (MRID 475602-08) was submitted and classified 

as supplemental because an OPPTS acute toxicity guideline does not exist for earthworms. 

Earthworms were exposed to the ester at concentrations between 123 and 909 mg a.e./kg-dw soil 

for 14 days. No mortalities or behavioral abnormalities were observed in the control or treatment 

groups throughout the definitive exposure period. By test termination, mean weight loss was 

4.33% in the solvent control and 5.41,5.36, 10.68, 12.98, and 12.18% in the 123,203,334,551, 

and 909 mg a.e./kg-dw soil treatment groups, respectively. The EC50 was >909 mg a.e./kg-dw 

soil. The NOAEC and LOAEC values, based on % body weight loss, were 203 and 334 mg 

a.e./kg-dw soil, respectively. 

Division. 

A study was submitted that evaluated the acute contact toxicity and acute oral toxicity of the acid 

on female young adult worker honey bees (MRID 475601-3 1). In the contact portion of the 

study, there was a complete lack of mortality and sublethal effects at any treatment level after 48 

hours. The LDso was >I00 pg a.e./bee, and the NOAEL was 100 yg a.e./bee. The contact portion 

of the study satisfies guideline requirements and classifies the acid as practically non-toxic. In 

the oral portion of the study, there were no significant mortalities. Sublethal effects were 

observed at 24 hours and included one apathetic bee at the 28.09 pg a.e./bee treatment level and 

eight bees with coordination problems at the 112.03 pg a.e./bee treatment level. However, these 

effects were not observed at 48 hours. The resulting LCso was >112.03 pg a.e./bee, and the 

NOAEL was 112.03 pg a.e./bee. The Agency does not have a data requirement or an acute oral 

toxicity guideline for the honey bee. Therefore, the data is considered supplemental but classified 

as acceptable since it was submitted in the same study as the acute contact toxicity test. The 

results from both the acute and contact toxicity tests are summarized in Table 4.11. Based on the 

toxicity values obtained from the acute contact and acute oral honey bee studies, no additional 

honey bee studies (foliage residue or field) are needed at this time. 

F1 and F2 male pup body 

weights) 

conducted by the Health Effects 

Toxicity 

acid 

(90.9-92.2%) 

Formal reviews of n arnrnalian data were 

Table 4.11. Toxic Effects in Earthworms (Eisenia fetiaa) and Honey Bee (Apis meUifera) Due to 

Acute Exposure to Aminocyclopyrachlor 

Acute Toxicity 

Ester 

(90.9% a.e.) 

850.3020 

Contact Toxicity 

acid 

(92.2%) 

Toxicity 

Classification 

S~Y 

Classification Study Type 

OECD TG 207 

ECS0: >909 mg a.e./kg-dw soil 

NOAEC: 203 mg a.e./kg-dw soil 

(% body weight) 

LDS0: >I00 pg a.e./bee 

NOAEL: 100 pg a.e./bee 

(no effects) 

Toxicity Value MRID # 

LCso: >909 mg a.e./kg-dw soil 

NIA 

Practically 

Non-toxic 

Supplemental 

Acceptable 

475602-08 

475601-3 1 

Dry Weight 

4.3 Comparison of Ester and Acid Toxicity 

Three studies were submitted that evaluated the acute effects of the ester on a freshwater fish, 

freshwater invertebrate, and upland game bird. Although rapid hydrolysis of the ester to the acid 

under environmental conditions is expected to occur, the submitted toxicity studies do not 

confirm equivalent toxicity. The submitted rainbow trout ester study (MRID 475602-06) was 

about an order of magnitude (or more due to the acid's non-definitive LCso) more toxic than the 

acid (MRID 475601-23). The daphnid ester study (MRID 475602-07) was about twice as toxic 

as the acid (MRID 475601-26). While both the ester and the acid bobwhite quail studies showed 

aminocyclopyrachlor to be practically non-toxic based on mortality, a sublethal effect was 

observed in the ester study; male body weight was affected by exposure to the ester (MRID 

475602-05) at a level about five times lower than the level that produced no effects by the acid 

(MRID 475601-18). Both the acute oral mammalian studies for the acid and ester did not show 

any toxicity or sublethal effects (MRID 475599-34,475600-27). 
4.4 Review of Incident Data 

As of October 30,2009, aminocyclopyrachlor had not yet been included in the EIIS 

ecological incidents. However, the lack of reported incidents does not preclude 

terrestrial and aquatic non-target organisms. 

An investigation of the EIIS database shows that concerns have been raised with a simi ar class 

of herbicides, the pyridine carboxylic acids. Several incidents have been reported invol 1 ing 

residues of clopyralid, picloram, and aminopyralid in compost causing crop injury; sode of these 

incidents have caused regulatory actions to be taken. Incidents involving aminopyralid n the 

United Kingdom resulted in a temporary suspension of sales of products containing \ 

aminopyralid. Incidents involving clopyralid resulted in the state of Washington bannin it from 

use on lawns and turf; the registrant subsequently voluntarily cancelled clopyralid's use on lawns 

in Washington. Similarly, the California Department of Pesticide regulation cancelled 

clopyralid's uses on residential lawns. Residues detected in lawn clippings and compos 1 have 

prompted other states to be on alert for potential issues involving these types of herbicides. 

I 

Although aminocyclopyrachlor belongs to the pyrimidine carboxylic acids family, it is 

systemic, and has high seedling emergence toxicity. Therefore, aminocyclopyrachlor 

may end up in treated plant materials used in compost or for feed for animals whose 

used in compost, which has the potential to cause similar incidents as those reported for 

aminopyralid, picloram, and clopyralid. 

4.5 Review of ECOTOX Data I 

I 

A search of the public ECOTOX database (htt~://cf~ub.e~a.~ov/ecotox) was conducted n 

October 30,2009. No studies were found that evaluated the effects of aminocyclopyrac lor on 

non-target organisms. 

4' I 

5 Risk Characterization ~ 

Risk characterization is the integration of exposure and effects characterization to deter ine the 

potential for ecological risks to non-target organisms including aquatic life, wildlife, an plants 

from the use of aminocyclopyrachlor according to the proposed labels. The risk charact rization 

provides an estimation and description of the risk; articulates risk assessment assumptio s, 

limitations, and uncertainties; synthesizes an overall conclusion; and provides the risk anagers 

with information to make regulatory decisions. i 

5.1 Risk Estimation: Integration of Exposure and Effects Data il 

Results of the exposure and toxicity effects data are used to evaluate the potential for adierse 

ecological effects on non-target species. For the assessment of potential risks of 

aminocyclopyrachlor, the risk quotient (RQ) method is used to compare exposure and mkasured 

acute or chronic toxicity values: I 

RQ = EEC / Toxicity Value 
where: EEC is the estimated environmental concentration generated by the exposure scenarios. 

The RQs are compared to the Agency's levels of concern (LOCs). These LOCs are the Agency's 

interpretive policy and are used to analyze potential risk to non-target organisms and the need to 

consider regulatory action (see Appendix D). These criteria are used to indicate when a 

pesticide's use as directed on the label has the potential to cause adverse effects on non-target 

organisms. 

5.11 Non-target Aquatic Fish, Invertebrates, and Plants 

The highest surface water concentrations resulting from aminocyclopyrachlor application were 

predicted using a non-crop scenario. Because the turf single application rates were lower than the 

maximum single application rate for non-crop areas, turf scenarios produced lower surface water 

concentration estimates. Application scenarios were selected to represent the entire range of soil 

and environmental conditions of the proposed actions. EECs are based on aminocyclopyrachlor 

parent. This conservative approach will approximate maximum exposure. 

Peak EECs were compared to acute toxicity endpoints to derive acute risk quotients. The 21-day 

EECs were compared to chronic toxicity endpoints (NOAEC values) to derive chronic risk 

quotients for invertebrates. The 60-day EECs were compared to chronic toxicity endpoints 

(NOAEC values) to derive chronic risk quotients for fish. 

Fish 

For the acid, no toxicity was observed at the highest concentration tested (120-129 rng a.e./L) for 

freshwater and estuarinelrnarine fish. Therefore, acute risk quotients were not calculated and 

RQs would not be expected to exceed LOCs. 

For the ester, an LCso was observed to be 13 mg a.e./L for bluegill sunfish. The resulting RQ of 

<0.01 (Peak EECIToxicity Value = 16.86 ppbl13,OOO ppb = 0.0013) does not exceed any of the 

. acute LOCs for the highest proposed application rate. 

The NOAEC produced by the chronic rainbow trout study was 11 mg a.e./L (acid). The resulting 

RQ of ~0.01 (60-day EECIToxicity Value = 16.64 ppbll1,OOO ppb = 0.0015) does not exceed the 

chronic LOC for the highest proposed application rate. A chronic estuarinelrnarine fish study was 

not submitted. The acute-to-chronic ratio cannot be used to predict potential chronic risks to 

estuarinelrnarine fish because the most sensitive acute freshwater fish uses the ester whereas the 

submitted chronic freshwater and acute estuarinelmarine fish studies use the acid. In addition, the 

acute estuarinelmarine fish study produced a non-definitive LCso. 

Freshwater Invertebrates 

For the acid, an LCs0 of 39.7 mg a.e./L was observed. The resulting RQ of <0.01 (Peak 

EECIToxicity Value = 16.86 ppb/39,700 ppb = 0.00042) does not exceed any of the acute LOCs 

for the highest proposed application rate. 
Similarly, for the ester, an LCso of 19.8 mg a.e./L was observed. The resulting RQ of <Q.Ol'(Peak 

EEClToxicity Value = 16.86 ppbl19,800 ppb = 0.00085) does not exceed any of the acdte LOCs 

for the highest proposed application rate. 

A definitive NOAEC was not produced by the chronic daphnid study (acid). The 

considered supplemental and the data did not allow for quantification of potential 

Chronic risks are assumed for non-listed and listed species due to lack of 

EstuarineIMarine Invertebrates I 

Mortality was not observed in the Eastern oyster shell deposition toxicity test; 

NOAEC of 67 mg a.e./L was observed. The resulting RQ of <0.01 (Peak 

16.86 ppbl67,OOO ppb = 0.00025) does not exceed the LOCs. No 

observed in the mysid shrimp acute toxicity test. Therefore, 

RQs would not be expected to exceed LOCs. 

A chronic estuarinelmarine invertebrate study was not submitted. Because the chronic f eshwater 

invertebrate study did not produce a definitive NOAEC, the acute-to-chronic ratio cann t be used 

to estimate potential chronic risks to estuarinelmarine invertebrates. Chronic risks are a sumed 

for non-listed and listed species due to lack of acceptable data. 

1 I 

Aquatic Plants 1 

Of the four non-vascular plant and one vascular plant studies submitted, blue-green algap 

produced the lowest ECso at 7.4 mg a.e./L. The resulting RQ of <0.01 (Peak 

= 16.86 ppb/7,400 ppb = 0.0023) did not exceed the acute LOC for 

using the NOAEC of 1.1 mg a.e./L for blue-green algae, the resulting RQ of <0.01 (Pe 

EEClToxicity Value = 16.86/1,100 ppb = 0.015) did not exceed the 

5.1.2 Non-target Terrestrial Animals I 

I 

Birds I 

I 

For the acid, no mortality or effects were observed in the bobwhite quail acute oral toxiclity test 

and the bobwhite quail and mallard duck acute dietary toxicity tests. Therefore, acute ris 

quotients were not calculated and RQs would not be expected to exceed LOCs. 

For the ester, no mortality was observed. However, male body weight was affected at a tkeatment 

level that was almost five times lower (442 mg a.e./kg-bw) than the level that produced 

sublethal affects with the acid (2075 mg a.e./kg-bw). The T-REX model does not 

quantify potential risks due to acute sublethal effects; refer to Section 5.2.2 for a 

potential risk due to reduced male body weight. 

The submitted avian reproduction studies were classified as invalid (see Section 4.2.1 fo 

details). Chronic reproductive risks to birds are assumed-for non-listed and listed species due to 

lack of acceptable data. I 
Mammals 

The acute oral rat studies submitted for both the acid and the ester did not show any mortality or 

signs of sublethal effects. Therefore, acute risk quotients were not calculated and RQs would not 

be expected to exceed LOCs. 

The chronic two-generation rat reproduction study produced a NOAEC of 5000 ppm and a 

corresponding estimated daily dose of 363 mg a.e./kg-bw. There were no exceedances of the 

chronic LOC at the highest single maximum application rate (0.284 lb a.e./acre). Chronic 

mammalian RQs are summarized in Table 5.1. 

Terrestrial Invertebrates 

EFED does not currently quantify risks to non-listed terrestrial non-target insects. Risk quotients 

are not calculated for these organisms. The honey bee is used as a surrogate for all terrestrial 

invertebrates. Aminocyclopyrachlor is classified as practically non-toxic based on the acute 

contact honey bee study >I00 pg a.i./bee). Similarly, the acute oral study resulted in a nondefinitive LDso as we11 (>112.03 y g a.i./bee). 

5.1.3 Terrestrial and Semi-aquatic Plants 

Terrestrial and semi-aquatic plants may be exposed to pesticides from runoff and spray drift. 

Semi-aquatic plants are those that inhabit low-lying wet areas that may be dry at certain times of 

the year. EECs for terrestrial and semi-aquatic plants are derived for areas adjacent to the 

treatment site. Acute RQs for terrestrial plants are derived by dividing the EEC by the ECZ5 from 

Tier I1 seedling emergence and vegetative vigor toxicity tests. Acute RQs for listed plant species 

are calculated by dividing the EEC by the NOAEC (if not available, an ECo5 is used) value from 

Tier I1 toxicity tests. 

Terrestrial plant EECs and toxicity endpoints are provided in Tables 3.10 and 4.11, respectively. 

EECs and RQs for applications to non-crop areas and turf are calculated using TerrPlant v1.2.2 

(Appendix C) and RQs are summarized in Table 5.2. 
As expected because aminocyclopyrachlor is an herbicide, several RQs exceeded the LOC. RQs 

ranged from <O. 1 (no spray drift due to granular application) to 

for listed dicots are based on an ECos because the NOAEC produced was 

ECos was outside the range of concentrations tested; therefore, there is 

this estimated toxicity value. 

concentrations. 

5.2 Risk Description 

A screening-level (Level I) risk assessment, based on the proposed uses of aminoc 

on non-crop areas and turf, suggests that levels of aminocyclopyrachlor in the env 

when compared with the most sensitive toxicity values for a given taxa, may resul 

adverse effects to terrestrial plants. These direct effects may also result in indirect 

target species through reduction of habitat or food sources. Due to lack of accept 

some taxa and lack of data for the degradates, not all potential risks are known. 

relationships (SARs), total toxic residue (TTR), and comparisons of environme 

concentrations relative to effects thresholds are methods used to reduce uncert 

degradate toxicities (see Section 5.2.3). 

5.2.1 Risks of Aminocyclopyrachlor to Aquatic Organisms I 

Acute and chronic risk quotients for all aquatic taxa were predicted to be below LOCs 

were available. However, in the absence of data, chronic risks are assumed for 

listed species; these taxa include freshwater and estuarinelmarine 

chronic toxicity data for freshwater invertebrates has a high 

ecological risk assessment by reducing uncertainties, which 

methods or weights of evidence. 
Although it was determined that the ester does not have equivalent toxicity to the acid (see 

Sections 2.2.3 and 2.6.2), the RQs that were calculated for the ester did not exceed any of the 

LOCs. Submission of acute estuarinelmarine and aquatic plant toxicity data for the ester has a 

low potential to add value to this ecological risk assessment because this additional data would 

have to show about a three to four orders of magnitude increase in toxicity over the available 

acid data to cause LOC exceedances. 

5.2.2 Risks of Aminocyclopyrachlor to Terrestrial Organisms 

Birds and Mammals 

Acute risk quotients for birds (and terrestrial amphibianslreptiles) would fall below LOCs due to 

lack of toxicity observed in submitted studies. However, in the avian acute oral study with the 

ester, reduction in male body weight was observed. This is a significant adverse sublethal effect 

that may result in changes in survival, growth, reproduction of wild birds. Chronic risks for birds 

cannot be precluded for non-listed and listed species due to lack of acceptable avian reproduction 

data. Submission of chronic toxicity data for birds has a high potential to add value to this 

ecological risk assessment by reducing uncertainties, which cannot be done using alternate 

methods or weights of evidence. Acute and chronic risk quotients for mammals fell below LOCs. 

From submitted studies, it was determined that the ester would have equivalent acute and chronic 

toxicity to birds and mammals as the acid. The currently proposed salt uses would not result in 

release of the salt to the environment; however, if different formulations for the salt are proposed 

in the future that would result in release of the salt to the environment, there may be potential for 

risks to birds and mammals. In this case, salt toxicity data may be needed to adequately assess 

potential risks. 

Terrestrial Plants 

Aminocyclopyrachlor is proposed for pre- and post-emergent control of broadleaf weeds and 

grasses. As such, it is expected that aminocyclopyrachlor would present potential risks to 

terrestrial and semi-aquatic plants. RQs exceeded LOCs for the highest use rates, including a 

granular form. The submitted labels include statements to reduce the potential for spray drift. If 

future uses are proposed for crop uses, it may be necessary to require a vegetative buffer strip to 

reduce risks to non-target plants. 

Although the current proposed uses are for non-crop areas and turf, a spray drift buffer analysis 

was conducted to estimate the buffer distances required to reduce the potential for effects to nontarget terrestrial plants. AgDRIFT was used to model the dissipation distance to the EC25 levels 

for non-listed terrestrial plants and to NOAEC levels for listed terrestrial plants. A drop size 

distribution of ASAE Very Fine to Fine was chosen to reflect the proposed label language (352- 

TI1 was used as an example). Buffer distances were calculated for the most sensitive endpoints 

for both monocots and dicots in the seedling emergence and vegetative vigor studies. For ground 

applications, only a Tier I assessment exists. In the event that a Tier I1 aerial application resulted 

in an out-of-range estimation (>lo00 feet), the Tier I11 AgDRIFT model could be used to 

estimate distances up to 2640 feet. 
Non-listed Species 

Dissipation distances ranged from 16.4 to >I000 feet for Tier I ground applications at e 

maximum proposed application rate (0.284 lb a.e./acre). At the lower rate (0.094 lb a.e. "; acre), 

dissipation distances ranged from 6.56 to >I000 feet for Tier I ground applications. For aerial 

applications (TI1 or TIII), dissipation distances ranged from 108.27 to >2640 feet at 

rate (0.284 lb a.e./acre). The lower application rate is proposed for ground 

Dissipation distances can be found in Table 5.3 for non-listed species. 

Listed Species 

Dissipation distances ranged from 19.68 to >lo00 feet for Tier I ground applications at 

maximum proposed application rate (0.284 lb a.e./acre). At the lower rate (0.094 lb a.e. 

dissipation distances ranged from 6.56 to >I000 feet for Tier I ground applications. 

applications (TI1 or TIII), dissipation distances ranged from 13 1.23 to >2640 feet at 

rate (0.284 1b a.e./acre). The lower application rate is proposed for ground 

Dissipation distances can be found in Table 5.4 for listed species. 

AgDRIFT does not address chronic concerns and only functions to model single applic 

Because the proposed application rates for aminocyclopyrachlor vary based on the 

site and end-user, the highest spray application rate was chosen (0.284 lb a.e./acre 

areas) and the lowest spray application rate was chosen (0.094 lb a.e./acre for 

uses). Other higher turf application rates have been proposed, but these are granular 

formulations. It is important to note that AgDRIFT assumes an entire acre has 

which may not necessarily be true in the case of non-crop area and turf uses. 
Ground water used for irrigation purposes is another potential route of exposure for terrestrial 

plants due to aminocyclopyrachlor's ability to leach to and accumulate in ground water. 

However, because the proposed uses are restricted to non-crop and turf areas, EFED did not 

estimate ground water EECs using SCI-GROW. If uses are proposed for crop areas in the future, 

this would be a valuable risk characterization tool. 

5.2.3 Potential Risks Due to Exposure to the Degradates 

No toxicity data on degradates have been submitted. Therefore, estimated toxicity values were 

generated using structure activity relationships (SARs) based on the ECOSAR program (version 

1.00) for the purpose of identifying degradates that may need additional investigation. ECOSAR 

is a publically available1 computerized predictive system that estimates the aquatic toxicity of 

chemicals. The program estimates a chemical's acute (short-term) toxicity and chronic (long-term 

or delayed) toxicity to aquatic organisms such as fish, aquatic invertebrates, and aquatic plants 

by using SARs. 

The results of this modeling exercise suggest that two degradates, IN-LXT69 and IN-YY905, 

may be more toxic than the parent to daphnids on a chronic basis (Table 5.5, see Appendix E 

for ECOSAR outputs). 

http://www .epa.gov/op~tjnewchemsltoo1$/2 1 ecosar, htm 

54 
Currently, there is no reliable SAR available that estimates the toxicity of pesticides to birds. 

Therefore, the evaluation of degradates conducted by the Health Effects Division (HE ) is 

generally used to evaluate the potential toxicity of degradates to mammals and birds. 4 Based on 

the analysis, IN-V0977 may be more toxic to birds and mammals than the parent chernipal. It 

forms via aqueous photolysis in quantities up to 14.6% of parent. Potential routes of ex 

birds and mammals for this degradate is through drinking water (dew and puddles) and 

exposure. However, by comparing the concentrations expected in the environment to 

thresholds, IN-V0977 would have to be more than two orders of magnitude more 

parent compound to cause LOC exceedances. 

Daphnid EC5O: 3 mgiL 

Algae Ec50: 10 mg/L 

Algae ChV: No SAR 

I 

I 

i 

IN-Q3007 

"I 

24.4 

Fish ChV: 

~ 

5mgiL 

Daphnid ChV: 2.7 mg/L i 

Algae ChV: 0.1 mg/L 

Aqueous Photolysis 

MRID 475602-1 1 

IN-VO977 

Fish LC50: 800 mg/L 

Daphnid EC5O: 200 mg/L ~ 

Algae Ec50: 0.8 mg/L 

14.6 Aqueous Photolysis 

MRID 475602- 1 1 

Fish LC50: > 100 rngL 

Daphnid EC5O: > 100 mgiL 

Algae Ec50: > 100 mg/L 

Fish ChV: >lOOmg/L 

Daphnid ChV: >I00 mg/L 

Algae ChV: > 100 mg/L 

I 
The total toxic residue (TTR) approach is used by EFED to evaluate potential risks to non-target 

organisms from aquatic exposure to degradates. TTRs represent potential combined exposures to 

the parent chemical and its degradates. However, due to the stability of the parent 

aminocyclopyrachlor, TTR values are expected to be similar to the EECs presented in this 

assessment for the parent chemical alone. 

Degradation half-lives used in GENEEC to estimate EECs for the parent chemical were long and 

essentially stable. Aqueous photolysis is the only degradation pathway input into GENEEC for 

which aminocyclopyrachlor degrades more rapidly (half-life = 7.8 days). However, GENEECestimated EECs are not sensitive to aqueous photolysis inputs. 

To investigate how aqueous photolysis affected EECs, GENEEC was run with short (tin = 1.0 

day) and long (tin = 0 day = stable) half-lives using the proposed maximum application rates for 

non-crop areas and turf. All other inputs were kept constant and were not changed from the 

inputs previously presented in Table 3.6. The results for non-crop uses show the peak EEC for 

photolysis set at tll2 = 0 days (stable) was 16.86 ppb and the peak EEC for photolysis set at tin = 

1 day was 16.84 ppb. The results for turf show the peak EEC for photolysis set at tl,2 = 0 days 

(stable) was 16.82 ppb and the peak EEC for photolysis set at tl,2 = 1 day was 16.82 ppb. Outputs 

(including the 21-day and 60-day EECs) are located in Appendix F. 

These results demonstrate that varying the aqueous photolysis input parameter has minimal 

effect on aquatic exposure values and potential risks. Because aqueous photolysis is the only 

significant rapid degradation pathway of aminocyclopyrachlor, this conservative TTR approach 

shows that aquatic exposure to the degradates would not result in any additional potential risks 

over those presented from exposure to the parent compound unless the degradates were a few to 

several orders of magnitude more toxic than the parent; submission of both aquatic and terrestrial 

toxicity data for the three degradates of concern, as predicted by SARs, has a low potential to 

add value to this ecological risk assessment. 
5.3 Threatened and Endangered Species Concern I 

To determine whether the proposed use sites for a pesticide are geographically associat~d with 

known locations of listed species, a screening-level search of the LOCATES (version 2110.3) 

database is conducted. The database compared county-level location data for listed spe 

county-level crop production data (as available in the 2002 agricultural census) to 

coarse overlaps of listed species with the proposed labeled uses of 

species are those that are currently on the Federal list of 

plants. 

Because proposed uses of aminocyclopyrachlor do not confine its use 

aminocyclopyrachlor may be used all over the United States. According to the 

and indirect effects in Table 5.4, every federally listed species may be 

uses of aminocyclopyrachlor. Therefore, a LOCATES analysis was 

I 

5.3.1 Action Area I 

For listed species assessment purposes, the action area is considered to be the area 

directly or indirectly by the Federal action and not merely the immediate area 

action. At the initial screening-level, the risk assessment considers broadly 

groups and so conservatively assumes that listed species within those broad 

located with the pesticide treatment area. This means that terrestrial plants 

assumed to be located on or adjacent to the treated site and aquatic 

located in a surface water body adjacent to the treated site. The 

listed species are located within an assumed area, which has 

exposure to the pesticide, and that exposures are likely to 

treatment area. This risk assessment presents the use of 

initial co-location of species with treatment areas. 

If the assumptions associated with the screening-level action area result in RQs that ar 

the listed species LOCs, a "no effect" determination conclusion is made with respect 

species in that taxa, and no further refinement of the action area is necessary. Furth 

below the listed species LOCs for a given taxonomic group indicate no concern for indi 

effects upon listed species that depend upon the taxonomic group covered by the RQ as 

resource. However, in situations where the screening assumptions lead to RQs in e 

listed species LOCs for a given taxonomic group, a potential for a "may affect" co 

and may be associated with direct effects on listed species belonging to that taxon 

may extend to indirect effects upon listed species that depend upon that taxonomi 

resource. In such cases, additional information on the biology of listed species, 

these species, and the locations of use sites could be considered to determine th 

screening assumptions regarding an action area apply to a particular listed org 

subsequent refinement steps could consider how this information would impa 

for a particular listed organism and may potentially include areas of exposure 

and downstream of the pesticide use site. 1 

1 
5.3.2 Taxonomic Groups Potentially at Risk: Direct Effects 

Based on available screening level information, for the proposed uses of aminocyclopyrachlor, 

there is a potential for direct effects to listed terrestrial plants. Due to lack of acceptable data for 

the acid, direct effects are assumed for birds (chronic) and freshwater invertebrates (chronic). 

Consequently, direct effects must be assumed for estuarinelmarine invertebrates (chronic); 

however, receipt of a chronic freshwater invertebrate study could eliminate this assumption. 

There is a potential concern for indirect effects upon the listed organisms by, for example, 

perturbing habitat, forage or prey availability. In conducting a screen for indirect effects, direct 

effect LOCs for each taxonomic group are used to make inferences concerning the potential for 

indirect effects upon listed species that rely upon non-endangered organisms in these taxonomic 

groups as resources critical to their life cycle. A summary of the risk conclusions and direct and 

indirect effects determinations is presented in Table 5.6. Because the proposed uses of 

aminocyclopyrachlor cannot be geographically limited, all federally listed species may be either 

directly or indirectly affected. 

The LOCATES database (version 2.9.7) identifies those U.S. counties that include non-crop and 

turf areas and that have federally-listed endangered or threatened species that may be directly or 

indirectly affected. The list of affected species derived from LOCATES was not included in.this 

assessment because the uses cover most of the United States and the direct and indirect effects 

includes most species. With additional refinement by exploring more detailed use patterns and 
species biology (e.g., geographic location, specific feeding habits, time of year llkely to utilize 

crop fields), some species listed may be determined to be not likely to be affected. 

5.3.3 Use of Probit Slope Response Relationship to Provide Information on the 

Endangered Species Levels of Concern I 

The Individual Effect Chance Model (Version 1. I), developed by the Environmental l?aJye and 

Effects Division, is used by the Agency to calculate the chance or probability of an indikidual 

mortality (effect) corresponding to the listed species' acute LOCs and calculated RQs. he 

model, which is an Excel spreadsheet tool, allows for calculations by entering the mean slope 

estimate (and the 95% confidence bounds of that estimate) as the slope parameter for th 

temporal nature of the exposure to make an effect determination. 

1 

spreadsheet. The generated information serves as a guide to establish the need for and 

of additional analysis that may be performed as well as evaluations of the 

Because screening-level acute LOCs were calculated and exceeded for only terrestrial 

aquatic plants in this assessment, probit analysis was not conducted. The endpoints 

plant studies include emergence, survival, shoot height, and dry weight rather than sing1 

mortality events. 

5.3.4 Indirect Effects Analysis 

The Agency acknowledges that pesticides have the potential to exert indirect effects upon the 

listed organisms by, for example, perturbing forage or prey availability, altering the ext nt of 

nesting habitat, etc. In conducting a screen for indirect effects, direct effect LOCs for ea 1 h 

taxonomic group are used to make inferences concerning the potential for indirect effect upon 

listed species that rely upon non-endangered organisms in these taxonomic groups as re ources 

critical to their life cycle. 

! 

I 

Based on direct risk to terrestrial plants, there may be potential indirect effects to aquati4 and 

terrestrial species that depend on these organisms (including their surrogates) as a sourc@ of food 

or habitat, including riparian habitats. Terrestrial plants serve several important habitat-r lated 

functions for listed species. In addition to providing habitat and cover, terrestrial vegeta ion also 

provides shelter for and cover from predators while foraging. Terrestrial plants also pro ide 

energy to the terrestrial ecosystem through primary production. Upland vegetation inclu ing 

grassland and woodlands provides cover during dispersal. Riparian vegetation helps to aintain 

the integrity of aquatic systems by providing bank and thermal stability, serving as a buf er to 

filter out sediment, nutrients, and contaminants before they reach the watershed, and ser ing as 

an energy source. 1 

6 Description of Assumptions, Uncertainties, Strengths, and Limit a tions 

6.1 Assumptions and Limitations Related to Exposure for all Taxa I 

There are a .number of areas of uncertainty in the aquatic and te~estrial risk assessments.) The 

toxicity assessment for terrestrial and aquatic animals is limited by the number of specied tested 

in the available toxicity studies. Use of toxicity data on representative species does not drovide 
information on the potential variability in susceptibility to acute and chronic exposures. 

This screening-level risk assessment relies on labeled statements of the maximum rate of 

aminocyclopyrachlor application, the maximum number of applications, and the shortest interval 

between applications. Together, these assumptions constitute a maximum use scenario. The 

frequency at which actual uses approach these maximums is dependant on resistance to the 

herbicide, timing of applications, and market forces. 

6.2 Assumptions and Limitations Related to Exposure for Terrestrial Species 

Variation in habitat and dietary requirements 

For screening terrestrial risk assessments, a generic bird or mammal is assumed to occupy either 

the treated field or adjacent areas receiving pesticide at a rate commensurate with the treatment 

rate on the field. The habitat and feeding requirements of the modeled species and the wildlife 

species may be different. It is assumed that species occupy, exclusively and permanently, the 

treated area being modeled. This assumption leads to a maximum level of exposure in the risk 

assessment. 

The acute studies have a fixed exposure period, not allowing for the differences in response of 

individuals to different durations of exposure. Further, for the acute oral study, 

aminocyclopyrachlor is administered in a single dose which does not mimic wild birds' exposure 

through multiple feeding. Also, it does not account for the effect of different environmental 

matrices on the absorption rate of the chemical into the animal. Because exposure occurs over 

several days, both the accumulated dose and elimination of the chemical from the body for the 

duration of the exposure determine the exact exposure to wildlife, however they are not taken 

into account in the screening assessment. There was also no assumption of an effect of repeated 

doses that change the tolerance of an individual to successive doses. 

Variation in diet composition 

The risk assessment and calculated RQs assume 100% of the diet is relegated to single food 

types foraged only from treated fields. The assumption of 100% diet from a single food type 

may be realistic for acute exposures, but diets are llkely to be more variable over longer periods 

of time. This assumption is likely to be conservative and will tend to overestimate potential risks 

for chronic exposure, especially for larger organisms that have larger home ranges. These large 

animals (e.g., deer and geese) will tend to forage from a variety of areas and move on and off of 

treated fields. Small animals (e.g., mice, voles, and small birds) may have home ranges smaller 

than the size of a treated field and will have little or no opportunity to obtain foodstuffs that have 

not been treated with aminocyclopyrachlor. Even if their home range does cover area outside the 

treated field, aminocyclopyrachlor may have runoff to areas adjacent to the treated field. 

Exposure routes other than dietary 

Only dietary and incidental ingestion of contaminated soils exposure is included in the exposure 

assessment. Other exposure routes are possible for animals in treated areas. These routes include 

ingestion of contaminated drinking water, dermal contact, inhalation, and preening. Because 
aminocyclopyrachlor does not volatilize appreciably, inhalation does not appear to be a 

significant contributor to the overall exposure. Given that aminocyclopyrachlor is solubile in 

water there exists the potential to dissolve in runoff and puddles on the treated field ma$ contain 

the chemical. If toxicity is expected through any of these other routes of exposure, then the risks 

of a toxic response to aminocyclopyrachlor is underestimated in this risk assessment. ~ 

Dietary Intake - The Differences Between Laboratory and Field Conditions i 

I 

There are several aspects of the dietary test that introduce uncertainty into calculation 04 the LCro 

value (Mineau, et al., 1994; ECOFRAM, 1999). The endpoint of this test is reported asithe 

concentration mixed with food that produces a response rather than as the dose ingested1 

Although food consumption sometimes allows for the estimate of a dose, calculations of the 

mglkglday are confounded by undocumented 

over the duration of the test. Usually, if 

the end of the five-day exposure period. 

allows for a measure of the average consumption per day for a group; 

be further confounded if birds die within a treatment group. The 

birds also complicates the estimate of the dose; controls often 

duration of the test. Since weights are only taken at the 

the end, the dose per body weight (mglkg) is difficult to 

interpretation of this test is also confounded because the 

of the intrinsic toxicity of the pesticide, but also the 

food. 

Further, the acute and chronic characterization of risk rely on comparisons of wildlife di tary 

residues with LCso or NOAEC values expressed in concentrations of pesticides in labor tory 

feed. These comparisons assume that ingestion of food items in the field occurs at rates 

commensurate with those in the laboratory. Although the screening assessment process adjusts 

dry-weight estimates of food intake to reflect the increased mass in fresh-weight wildlif food 

intake estimates, it does not allow for gross energy and assimilative efficiency differenc I s 

between wildlife food items and laboratory feed. On gross energy content alone, direct 

comparison of a laboratory dietary concentration- based effects threshold to a fresh-wei 

pesticide residue estimate would result in an underestimation of field exposure by food 

consumption by a factor of 1.25 - 2.5 for most food items. Only for seeds would the 

comparison of dietary threshold to residue estimate lead to an overestimate of 

Differences in assimilative efficiency between laboratory and wild diets suggest that c 

screening assessment methods do not account for a potentially important aspect of food 

requirements. Depending upon species and dietary matrix, bird assimilation of wild 

ranges from 23 - 80%, and mammal's assimilation ranges from 41 - 85% (U.S. 

Protection Agency, 1993). If it is assumed that laboratory chow is formulated 

assimilative efficiency (e.g., a value of 85%), a potential for underestimation 

exist by assuming that consumption of food in the wild is comparable with 

laboratory testing. In the screening process, exposure may be 

rates are not related to food consumption. 
Finally, the screening procedure does not account for situations where the feeding rate may be 

above or below requirements to meet free living metabolic requirements. Gorging behavior is a 

possibility under some specific wildlife scenarios (e.g., bird migration) where the food intake 

rate may be greatly increased. Kirkwood (1983) has suggested that an upper-bound limit to this 

behavior might be the typical intake rate multiplied by a factor of 5. In contrast is the potential 

for avoidance, operationally defined as animals responding to the presence of noxious chemicals 

in their food by reducing consumption of treated dietary elements. This response is seen in 

nature where herbivores avoid plant secondary compounds. 

In the absence of additional mformation, the acute oral LD50 test provides the best estimate of 

acute effects for chemicals where exposure can be considered to occur over relatively short 

feeding periods, such as the diurnal feeding peaks common to avian species (ECOFRAM, 1999). 

Incidental Pesticide Releases Associated with Use 

This risk assessment is based on the assumption that the entire treatment area is subject to 

aminocyclopyrachlor application at the rates specified on the label. In reality, there is the 

potential for uneven application of aminocyclopyrachlor through such plausible incidents as 

changes in calibration of application equipment, spillage, and localized releases at specific areas 

of the treated field that are associated with specifics of the type of application equipment used 

(e.g., increased application at turnabouts when using older application equipment). 

6.3 Assumptions and Limitations Related to Exposure for Aquatic Species 

The fate and transport database for aminocyclopyrachlor was sufficient to conduct aquatic 

modeling for exposure assessment of aquatic species. The GENEEC model was used to produce 

estimated exposure concentrations. Because no RQs exceeded LOCs for aquatic species, these 

exposure estimates did not need to be refined by using PRZMIEXAMS. Because 

aminocyclopyrachlor is a new chemical, no monitoring data were available to compare to the 

model estimates. 

6.4 Assumptions and Limitations Related to Effects Assessment 

As described in Sections 2.2.3 and 2.6.2, the lack of acceptable data for the acid, ester, and 

certain degradates results in effects uncertainties for the respective taxa. However, for many taxa, 

alternate methods and additional weights of evidence could be used to describe potential risks. 

For taxa, such as freshwater and estuarinelmarine invertebrates (chronic) and birds (chronic), 

where alternate approaches could not be used in the absence of data, risks cannot be precluded 

for non-listed and listed species. 

Age class and sensitivity of eflects thresholds 

It is generally recognized that test organism age may have a significant impact on the observed 

sensitivity to a toxicant. The screening risk assessment acute toxicity data for fish are collected 

on juvenile fish between 0.1 and 5 grams. Aquatic invertebrate acute testing is performed on 

recommended immature age classes (e.g., first instar for daphnids, second instar for amphipods, 

stoneflies and mayflies, and third instar for midges). Similarly, acute dietary testing with birds is 
also performed on juveniles, with mallard being 5-10 days old and quail 10-14 days oldi. 

I 

Testing of juveniles may overestimate toxicity of older age classes for pesticide active I 

ingredients, such as aminocyclopyrachlor, that act directly (without metabolic transfor 

because younger age classes may not have the enzymatic systems associated with 

xenobiotics. The screening risk assessment has no current provisions for a 

method that accounts for this uncertainty. In so far as the available toxicity 

ranges of sensitivity information with respect to age class, the risk 

sensitive life-stage information as the conservative screening endpoint. 

Use of the Most Sensitive Species Tested , 

Although the screening risk assessment relies on a selected toxicity endpoint from the ost 

sensitive species tested, it does not necessarily mean that the selected toxicity endpoint ? eflect 

sensitivity of the most sensitive species existing in a given environment. The relative pa/sition of 

the most sensitive species tested in the distribution of all possible species is a function o the 

overall variability among species to a particular chemical. In the case of listed species, here is 

uncertainty regarding the relationship of the listed species' sensitivity and the most sens tive 

species tested. 

1 i 

The Agency is not limited to a base set of surrogate toxicity information in establishing isk 

assessment conclusions. The Agency also considers toxicity data on non-standard test s ecies 

when available. 

4 I 
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sorption, bioconcentration and algal toxicity of sulfonwea herbicides. Aquat Toxicol 3 1: 

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2252. 

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Merritt, R. W. and K. W. Cumrnins, eds. 1984. An Introduction to the Aquatic Insects o North F America 2nd ed. Kendalmunt Publishing Company, Dubuque, Idaho. 722 pp. ~ 

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Uesugi Y, Ueji M, Koshioka M (ed) (1997) Pesticide Data Book, 3rd Edition. Soft ~cienbe 

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Urban D.J. and N.J. Cook. 1986. Hazard Evaluation Division Standard Evaluation Proqedure 

Ecological Risk Assessment. EPA 54019-85-001. U.S. Environmental Protectiob 

Agency, Office of Pesticide Programs, Washington, DC. 
USDA Crop Profiles. http://www.ipmcenters.or~cropprofiles/CP form.cfm 

U.S. EPA 1993. Wildlife Exposure Factors Handbook. Volume I of 11. EPN600lR-931187a. 

Office of Research and Development, Washington, D. C. 20460. EPN600lR-931187a. 

U.S. EPA 1998. Guidance for Ecological Risk Assessment. Risk Assessment Forum. 

EPN630lR-95/002F, April 1998. 

U.S. EPA 2002. Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides Input Parameter Guidance. Version I1 February 28,2002. 

U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. 

U.S. EPA 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. Office of Prevention, Pesticides, and Toxic Substances. Office of Pesticide 

Programs. Washington, D.C. January 23,2004. 

Wolfe, N.L., M.E-S. Metwally and A.E. Moftah. 1989. Hydrolytic Transformations of Organic 

Chemicals in the Environment. In: Reactions and Movement of Organic Chemicals in 

Soils. B.L. Sawhney and K. Brown, (Eds), Soil Science of America and American 

Society of Agronomy, Madison, WI. P.229-242. 

Wolfe, N.L. 1990. Abiotic Transformations of Toxic Organic Chemicals in the Liquid Phase and 

Sediments. In: Toxic Organic Chemicals in Porous Media. Z. Gerstl, Y. Chen, U. 

Mingelgrin and B. Yaron. (Eds.). Springer-Verlag, New York. p. 136- 147. 
Appendix A. GENEEC Output 

Parent: 

Non-crop aerial (spray) I 

RUN No. 1 FOR ACP Acid ON Non-Crop * INPUT VALUES * ~ ................................................................... t 

RATE (#/Ac) NO .APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCDR~ 

ONE (MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) ................................................................... t 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) ................................................................... lMETABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINE~I 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND) (POND) 1 

I ................................................................... 

373.00 2 N/ A 7.80- 967.20 .OO 967.201 

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 ................................................................... t 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY ~ 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC -------------------------------------------------------------------& 

16.86 16.85 16.79 16.64 16.53 

Non-crop ground (spray) 

RUN No. 1 FOR ACP Acid ON Non-Crop * INPUT VALUES * ................................................................... t 

RATE (#/Ac) NO .APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCOR~ 

ONE (MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) I 

................................................................... I 

.284( .284) 1 1 12.0 2810.0 GRHIFI( 6.6) -0 -0 I 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) .................................................................... I 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINEq 

(FIELD) RAIN/RUNOFF (POND) ( POND-EFF) ( POND) (POND) ................................................................... 4 

373.00 2 N/ A 7.80- 967.20 -00 967.20 ~ 

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2004 ................................................................... i 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY ~ 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 1 ______-_____-______-------------------------------------------------l 

16,47 16.46 16.40 16.26 16.15 
Turf ground (granule) 

RUN No. 1 FOR ACP Acid ON Turf * INPUT VALUES * .................................................................... 

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

ONE ( MULT ) INTERVAL KOC (PPM ) (%DRIFT) (FT) (IN) .................................................................... 

.108( .307) 3 30 12.0 2810.0 GRANUL( .O) .O .O 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) .................................................................... 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND) ( POND ) 

.................................................................... 

373.00 2 N/ A 7.80- 967.20 .OO 967.20 

GENERIC EECS (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 .................................................................... 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 
Appendix B. T-REX Output 

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs 

1 application at 0.284 lb a.e./acre 

Size class not used for dietary risk quotients 

Size class not used for dietary risk quotients 

Appendix C. TerrPlant Output 

1 application at 0.108 lb a.e./acre (ground - granule) 

1 application at 0.094 lb a.e./acre (ground - spray) 

Runoff to semi-aquatic areas 

Spray drift 

Total for dry areas 

Total for semi-aquatic areas 

1 application at 0.284 lb a.e./acre (ground - spray) 

(M)*R*10 

A*D 

((M)*R)+(A*D) 

((A/I)*R* 1 O)+(A*D) 

Runoff to semi-aquatic areas 

Spray drift 

Total for dry areas 

Total for semi-aquatic areas 

0.054 

0 

0.0054 

0.054 

(M) *R* 10 

A*D 

((M>*R)+(A*D> 

((M)*R* 10)+(A*D) 

Table C-5. EECs for Aminocycbpyrachlor 

0.047 

0.00094 

0.00564 

0.04794 

Description Equation EEC 
1 application at 0.284 lb a.e./acre (aerial - spray) 

0.0142 

0.142 

0.00284 

0.01704 

0.14484 

Runoff to dry areas 

Runoff to semi-aquatic areas 

Spray drift 

Total for dry areas 

Total for semi-aquatic areas 

Monocot 

Monocot 

Dicot 

Dicot 

(M)*R 

(Ah) *R* 10 

A*D 

((M)*R)+(A*D) 

((M) *R* 10)+(A"D) 

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group. 

non-listed 

listed 

non-listed 

listed 

Runoff to semi-aquatic areas 

Spray drift 

Total for dry areas 

Total for semi-aquatic areas 

0.36 

0.43 

32.15 

34.78 

(M)*R*10 

A*D 

((MI *RR)+(A*D) 

((M)*R* 1 O)+(A*D) 

0.142 

0.0142 

0.0284 

0.1562 

3.02 

3.68 

273.28 

295.59 

0.49 

1.01 

37.87 

3641.03 
Appendix D. RQ Methods and LOC Definitions 

Acute Risk EEC/LCSO or LD50/sqft or LDSO/day 

Acute Restricted Use EEC/LCSO or LDSO/sqft or LD5dday (or LD50 < 50 

Acute Listed Species EEC/LCSo or LDS0/sqft or LD50/day 

Chronic Risk EECINOAEC 

Acute Risk EEC/LCSO or LD50/sqft or LDSO/day 

Acute Restricted Use 

Acute Listed Species EEC/LCSO or LDSO/sqft or LDSO/day 

Chronic Risk EECINOAEC 

Acute Risk EEC/LCSO or ECSo 

Acute Restricted Use EEC/LCSo or ECSo 

Acute Listed Species EEC/LCSo or ECS0 

Chronic Risk EECINOAEC 

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC/EC25 

Acute Listed Species EEC/ECo5 or NOAEC 

Acute Risk EEC/ECSo 

The Risk Quotient Method is the means by which the Environmental Fate and Effects qivision 

(EFED) integrates the results of exposure and ecotoxicity data. In this method, both acu:e 

chronic risk quotients (RQs) are calculated by dividing exposure estimates by the most 

ecotoxicity values derived from the studies. Calculated RQs are then compared to OPP's 

concern (LOCs). The LOCs are the criteria used by OPP to indicate potential risk to 

organisms and the need to consider regulatory action. EFED has defined LOCs for acute 

potential restricted use, and for listed species. Risk presumptions, along with the corresr 

RQs and LOCs are summarized in the table below. 

and 

sensitive 

levels of 

nor.-target 

risk, 

onding 
Appendix E. ECOSAR Outputs 

SMILES : cl(C2CC2)ncc(CL)c(N)nl 

CHEM : 

CAS Nurn: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C7 H8 CLl N3 

MOL WT : 169.61 

Log Kow: 1 .O1 (KowWin estimate) 

Melt Pt: 

Wat Sol: 8453 mg/L (WskowWin estimate) 

ECOSAR v1 .OO Class(es) Found .............................. 

Aniline~ (Aromatic Amines) 

Predicted 

ECOSAR Class Organism Duration 

Anilines (Aromatic Amines) : Fish 96-hr 

Anilines (Aromatic Amines) : Fish 14-day 

Anilines (Aromatic Amines) : Daphnid 48-hr 

Anilines (Aromatic Amines) : Green Algae 96-hr 

Anilines (Aromatic Amines) : Fish 

Anilines (Aromatic Amines) : Daphnid 

Anilines (Aromatic Amines) : Green Algae 

End Pt m& (ppm) -------- ------ ---------- 

LC50 80.220 

LC50 212.499 

LC50 2.527 

EC50 9.897 

ChV 0.376 

ChV 0.052 

ChV 6.529 

-------- ------ ---------- 

Neutral Organic SAR : Fish 96-hr LC50 897.019 

(Baseline Toxicity) : Daphnid 48-hr LC50 459.298 

Green Algae 96-hr EC50 131.980 

Fish ChV 87.035 

Daphnid ChV 35.617 

Green Algae ChV 39.875 

Note: * = asterisk designates: Chemical may not be soluble 

enough to measure this predicted effect. 

Anilines (Aromatic Amines): 

For Fish Acute Toxicity Values: 2,3,5,6-Tetrachloroaniline is 19 times 

more toxic than predicted by this SAR. Tetrabromoaniline may be more toxic 

than predicted by this SAR as well. 

For Daphnid and Green Algae Toxicity Values: Tetrachloro- and tetrabromaniline may be 20 times toxic than predicted by this SAR. 

N-Substituted anilines are less toxic than predicted by these SARs; 

for these compounds, Neutral Organic SARs are used. 

ECOSAR v1.00 SAR Limitations: 

Maximum LogKow: >7.8 (Fish 96-hr LC50, Daphnid 48-h LC50) 

Maximum LogKow: >3.7 (Fish 14-day LC50) 

Maximum LogKow: >4 (Green Algae 96-hr EC50 and ChV) 

Maximum LogKow: >4.3 (Fish ChV) 

Maximum LogKow: >2.4 (Daphnid ChV) 

Maximum Mol Wt: 1000 

Baseline Toxicity SAR Limitations: 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 
Maximum Mol Wt: 1000 
Degradate: IN-QFH57 

SMILES : c 1 (C2CC2)nc(C(#N))c(C(=O)O)nl 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3 : 

MOL FOR: C8 H7 N3 02 

MOL WT : 177.16 

Log Kow: 0.83 (KowWm estimate) 

Melt Pt: 

Wat Sol: 6030 mglL (WskowWm estimate) 

ECOSAR v1.00 Class(es) Found 

Imidazoles-acid 

Predicted 

ECOSAR Class Organism Duration End Pt mgll (ppm) -------- ------ ---------- 

--z Acid moeity found: Predicted values multiplied by 10 

Imidazoles-acid : Fish 96-hr LC50 1135.075 

Imidazoles-acid : Daphnid 48-hr LC50 13.191 

Imidazoles-acid : Fish ChV 101.028 ! 

Imidazoles-acid : Daphnid ChV 0.912 ! 

-------- ------ 

Neutral Organic SAR Fish 96-hr LC50 1332.358 

(Baseline Toxicity) Daphnid 48-hr LC50 667.463 

: Green Algae 96-hr EC50 178.090 

: Fish ChV 129.792 

: Daphnid ChV 50.132 

: Green Algae ChV 52.060 

Note: * = asterisk designates: Chemical may not be soluble 

enough to measure this predicted effect. 

Note: ! = exclamation designates: The toxicity value was determined from 

a predicted SAR using established acute-to-chronic ratios and ECOSAR 

regression techniques which are documented in the supporting Technical 

Reference Manual. When possible, this toxicity value should be 

considered in a weight of evidence approach. 

Imidazoles: 

For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical 

is greater than 5.0, or if the compound is solid and the LC50 exceeds the 

water solubility by lox, no effects at saturation are predicted for these 

endpoints. 

For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by lox, no effects at saturation are predicted for these endpoints. 

For All Chronic Toxicity Values: If the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by 10X, no effects at saturation are predicted for these endpoints. 

ECOSAR v1 .OO SAR Limitations: --..------------------------ 

Maximum LogKow: 5.0 (LC50) 

Maximum LogKow: 6.4 (EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

Baseline Toxicity SAR Limitations: 
---------------.----------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 
SMILES : ClCClC(=O)N 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemJD3: 

MOL FOR: C4 H7 N10 1 

MOL WT : 85.11 

Log Kow: -0.37 (KowWin estimate) 

Melt Pt: 

Wat Sol: 2.623E+005 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found -------------....------------- 

Amides 

ECOSAR Class Organism ........................... 

Amides : Fish 

Amides : Daphnid 

Amides : Green Algae 

Amides : Fish 

Amides : Daphnid 

Amides : Green Algae 

Predicted 

Duration End Pt mg/L (ppm) -------- ------ 

---7- 

96-hr LC50 814.468 

48-hr LC50 202.630 

96-hr EC50 0.853 

ChV 4.815 

ChV 2.673 ! 

ChV 0.142 

------ --------- 

Neutral Organic SAR: Fish 96-hr LC50 6585.711 

(Baseline Toxicity) : Daphnid 48-hr LC50 2854.948 

: Green Algae 96-hr EC50 466.243 

: Fish ChV 658.740 

: Daphnid ChV 173.542 

: Green Algae ChV 109.548 

Note: * = asterisk designates: Chemical may not be soluble 

enough to measure this predicted effect. 

Note: ! = exclamation designates: The toxicity value was determined from 

a predicted SAR using established acute-to-chronic ratios and ECOSAR 

regression techniques which are documented in the supporting Technical 

Reference Manual. When possible, this toxicity value should be 

considered in a weight of evidence approach. 

Amides : -- - -- -- 

No limitations known at this time. 

ECOSAR v1.00 SAR Limitations: 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

Baseline Toxicity SAR Limitations: 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 
SMILES : ClCClC(=O)O 

CHEM : 

CAS Num: 

ChemID 1 : 

ChemID2: 

ChemID3: 

MOL FOR: C4 H6 02 

MOL WT : 86.09 

Log Kow: 0.88 (KowWin estimate) 

Melt Pt: 

Wat Sol: 9.145E+004 mg/L (WskowWin estimate) 

ECOSAR v1 .OO Class(es) Found 

Neutral Organics-acid 

Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

-----dm---------- -------- ------ ---------- 

--> Acid moeity found: Predicted values multiplied by 10 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

Neutral Organics-acid 

: Fish 96-hr 

: Fish 14-day 

: Daphnid 48-hr 

: Green Algae 96-hr 

: Fish 30-day 

: Daphnid 

: Green Algae 

: Fish (SW) 96-hr 

: Mysid Shrimp 96-hr 

: Fish (SW) 

: Mysid Shrimp (SW) 

: Earthworm 14-day 

LC50 

LC50 

LC50 

EC50 

ChV 

ChV 

ChV 

LC50 

LC50 

ChV 

ChV 

LC50 

Note: * = asterisk designates: Chemical may not be soluble 

enough to measure this predicted effect. 

Neutral Organics: 

--------..------ 

For Fish LC50 (96-h), Daphnid LC50, Mysid: If the log Kow is greater 

than 5.0, or if the compound is solid and the LC50 exceeds the water 

solubility by lox, no effects at saturation are predicted. 

For Fish LC50 (14-day) and Earthworm LC50: If the log Kow is greater 

than 6.0, or if the compound is solid and the LC50 exceeds the water 

solubility by lox, no effects at saturation are predicted. 

For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by lox, no effects at saturation are predicted for these endpoints. 

For All Chronic Toxicity Values: Jf the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by lox, no effects at saturation are predicted for these endpoints: 

ECOSAR v1.00 SAR Limitations: ............................ 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50) 

Maximum LogKow: 6.0 (Fish 14-day LC50; Earthworm LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 
SMILES : ClCClC(=N)N 

CHEM : 

CAS Num: 

ChemID 1 : 

ChemID2: 

ChemID3: 

MOL FOR: C4 H8 N2 

MOL WT : 84.12 

Log Kow: -1.72 (KowWin estimate) 

Melt Pt: 

Wat Sol: IE-I-006 mg/L (WskowWin estimate) 

ECOSAR v1 .OO Class(es) Found .............................. 

Aliphatic Amines 

Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) ------- ---------- 

Aliphatic Amines : Fish 96-hr LC50 2559.187 

Aliphatic Amines : Daphnid 48-hr LC50 119.684 

Aliphatic Amines : Green Algae 96-hr EC50 15.333 

Aliphatic Amines : Fish ChV 32.172 

Aliphatic Amines : Daphnid ChV 0.023 

Aliphatic Amines : Green Algae ChV 16.327 

Aliphatic Amines : Fish (SW) 96-hr LC50 2642.790 

Aliphatic Amines : Mysid Shrimp (SW) 96-hr LC50 124.511 

Aliphatic Amines : Green Algae (SW) 96-hr EC50 15.246 

Aliphatic Amines : Fish (SW) ChV 32.172 

Aliphatic Amines : Mysid Shrimp (SW) ChV 0.023 

Aliphatic Amines : Green Algae (SW) ChV 13.870 

------------------ ------ 

Neutral Organic SAR : Fish 96-hr LC50 91250.281 

(Baseline Toxicity) : Daphnid 48-hr LC50 33580.477 

: Green Algae 96-hr EC50 3145.013 

: Fish ChV 9404.913 

: Daphnid ChV 1606.282 

: Green Algae ChV 576.973 

Note: * = asterisk designates: Chemical may not be soluble 

enough to measure this predicted effect. 

Aliphatic Amines: 

---------------- 

For Fish 96-hr LC50: For aliphatic amines with log Kow greater than 7.0. 

a test duration of greater than 96 hrs may be required for proper 

expression of toxicity. Also, if the toxicity value obtained by the use 

of this equation exceeds the water solubility (measured or estimated), 

mortalities greater than 50% would not be expected in a saturated 

solution during an exposure period of 96 hrs. 

For Daphnid 48-hr LC50: For aliphatic amines with log Kow greater than 

5.0, a test duration of greater than 48 hrs may be required for proper 

expression of toxicity. Also, if the toxicity value obtained by the use 

of this equation exceeds the water solubility (measured or estimated), 

significant mortalities would not be expected in a saturated solution 

during an exposure period of 48 hrs. 

For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 7, or if the compound is solid and the EC50 exceeds the water 

solubility by IOX, no effects at saturation are predicted for these endpoints. 

For.Mysid Shrimp Acute Toxicity Values: -If the log Kow of the chemical is 

greater than 6, or if the compound is solid and the EC50 exceeds the water 

solubility by lox, no effects at saturation are predicted for these endpoints. 
For Fish and Daphnid Chronic Toxicity Values: If the log Kow of the chemical 

is greater than 8.0, or if the compound is solid and the ChV exceeds the water 

solubility by lox, no effects at saturation are predicted for these endpoints. 

For Green Algae Chronic Toxicity Values: If the log Kow of the chemical 

is greater than 7.0, or if the compound is solid and the ChV exceeds the water 

solubility by lox, no effects at saturation are predicted for these endpoints. 

ECOSAR v1.00 SAR Limitations: ............................ 

Maximum LogKow: 6.0 (Fish, Mysid LC50) 

Maximum LogKow: 5.0 (Daphnid LC50) 

Maximum LogKow: 7.0 (Green Algae EC50) 

Maximum LogKow: 8.0 (Fish, Daphnid ChV) 

Maximum LogKow: 7.0 (Green Algae ChV) 

Maximum Mol Wt: 1000 

Baseline Toxicity SAR Limitations: ................................. 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 
Appendix F: GENEEC Outputs for Total Toxic Residue Approach 

RUN No. 1 FOR ACP Acid ON Non -Crop Half-Life= 0 days 

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

ONE (MULT) INTERVAL KOC (PPM ) (%DRIFT) (FT) (IN) .................................................................... 

.284 ( -284) 1 1 12.0 2810.0 AERL-B( 13.0) .O .O 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) .................................................................... 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND ) ( POND ) .................................................................... 

373.00 2 N/ A .OO- .OO .OO .OO 

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 .................................................................... 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

RUN No. 2 FOR ACP Acid ON Non-Crop1 Half-Life=l day 

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

ONE (MULT ) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN) 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) .................................................................... 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND) ( POND ) .................................................................... 

373.00 2 N/ A 1.00- 124.00 .OO 124.00 

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 .................................................................... 

PEAK MAX 4 DAY MAX21DAY MAX60DAY MAX90DAY 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

RUN No. 1 FOR ACP Acid ON Turf Half-Life= 0 days .................................................................... 

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP 

ONE (MULT ) INTERVAL KOC (PPM ) (%DRIFT) (FT) (IN) .................................................................... 

.108( .307) 3 30 12.0 2810.0 GRANUL( .O) .O .O 
FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND) (POND) ' __________-------__------------------------------------------------T 

373.00 2 N/ A -00- .OO .OO . 00 I 

GENERIC EECS (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 200i ................................................................... I 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY ~ 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC ................................................................... 

16.82 16.82 16.82 16.80 16.79 

RUN No. 2 FOR ACP Acid ON Turf Half-Life= 1 daq -------------------------------------------------------------------L 

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORB 

ONE (MULT) INTERVAL KOC (PPM ) (%DRIFT) (FT) (IN) 

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINE9 

(FIELD) RAIN/RUNOFF (POND) (POND-EFF) ( POND) ( POND) -------------------------------------------------------------------4 

373.00 2 N/A 1.00- 124.00 .OO 124.00 

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001 ................................................................... 

PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY 7 

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC 

______---------_---------------------------------------------------* 

16.82 16.75 16.31 15.36 14.69