Page 2 of 63 

The Registration Review considers existing uses; however, aminopyralid is proposed for use via direct 

application to water for aquatic plant control, and this use is evaluated as well in this problem formulation. 

Aminopyralid acid and its associated salts are plant growth regulators. Aminopyralid in both salt and acid 

forms will readily dissociate in water at ambient pH to yield the aminopyralid anion. Because of 

similarities in metabolism and effects in animals, plants, and the environment, aminopyralid in its acid and 

salt forms were considered equivalent in previous risk assessments, and for the purposes of this problem 

formulation are considered equivalent as well. The term “aminopyralid” is thus used in this document to 

refer to compounds containing the aminopyralid anion generically, unless a specific form is noted. 

This problem formulation describes the methods planned to be used during the completion of drinking 

water and ecological risk assessments in support of Registration Review, and provides an overview of the 

environmental fate, ecological effects, and potential risks associated with the use of aminopyralid as well 

as uncertainties unique to the risk assessment of aminopyralid. This document also identifies additional 

studies that would address uncertainties in assessing ecological risk associated with current uses of 

aminopyralid. Uncertainties include: 

• The fate database is incomplete based on the environmental fate data requirements outlined in the 

Code of Federal Regulations Title 40 Part 158 (40CFR158) Subpart N1

 and data are needed to 

complete and reduce uncertainty in risk assessments. Additional data on the following fate parameters

are recommended. 

o Aerobic aquatic metabolism data (OCSPP2

 Guideline 835.4300). Aerobic conditions were not 

maintained throughout the aerobic aquatic studies. In the absence of an acceptable study, the model 

half-life input for aerobic aquatic metabolism will be assumed to be twice the aerobic soil 

metabolism half-life, per EFED’s input parameter guidance (USEPA, 2009b). Additional data are 

recommended in part because of potential risk to terrestrial plants via exposure from irrigation 

water. Additionally, this study is recommended because a proposed use involves direct application 

to water. This study will reduce uncertainty regarding potential exposure to aquatic organisms and 

terrestrial plants. Aminopyralid in any of its three chemical forms (salt or acid) listed above may be 

used as the test item.

o Dissipation study in compost (Non-Guideline): Aminopyralid applied to vegetative matter used 

as animal feed, from which manure is produced that is subsequently composted, has been found to 

remain present in sufficient quantity to damage non-target plants (see Section 6c Ecological 

Incidents). A study is requested to quantify rates of aminopyralid degradation within composted 

material. The study will be used to characterize potential risk from aminopyralid residues in 

compost, and to help identify potential mitigation measures for existing uses. A protocol for this 

non-guideline study should be submitted to the EPA for review and approval prior to initiation of 

the study. Aminopyralid in any of its three chemical forms (salt or acid) listed above may be used 

as the test item.

o Environmental Chemistry Methods and Independent Laboratory Validation on Compost 

(OCSPP Guideline 850.6100): Data are requested for environmental chemistry methods (ECM) 

on compost and independent laboratory validation (ILV) of the method. For compost, methods 

should be derived that can be used with equipment found in state laboratories and use analytical 

standards that can be readily obtained. Methods should be able to detect parent and any degradates 

that are identified as residues of concern. Currently, the residues of concern identified include 

aminopyralid and unextracted residues. 

o Data to better understand risk from residues in groundwater used as irrigation water 

(OCSPP 835.7100): Residues of aminopyralid have been detected in groundwater and other 

 

1

 CFR. 2013. Title 40 (Protection of the Environment), Chapter 1 (Environmental Protection Agency), Subchapter E (Pesticide 

Programs), Part 158 (Data Requirements for Pesticides), Subpart N (Environmental Fate) http://www.ecfr.gov/cgi-bin/textidx?c=ecfr&SID=ff5c7fef3645e7cd5abceca0b597bccb&tpl=/ecfrbrowse/Title40/40cfr158_main_02.tpl

2

The Series 835 Fate Guidelines were completed when the Office of Chemical Safety and Pollution Prevention (OCSPP) was 

known as the Office of Prevention, Pesticides, and Toxic Substances (OPPTS). 
Page 3 of 63 

picolinic acids have incidents where residues of picolinic acids in groundwater resulted in damage 

to terrestrial plants. Additionally, risk assessments for aminopyralid have identified this pathway as 

a potential concern for damage to terrestrial plants. Additional data are recommended to better 

understand the potential for risk due to residues of aminopyralid in groundwater. Studies that 

would be useful include a prospective groundwater monitoring study or studies to refine 

groundwater modeling inputs for the Pesticide Root Zone Model for Groundwater (PRZM-GW) 

model. A prospective groundwater monitoring study could be used to determine where 

groundwater concerns were likely to occur and whether what we predict based on laboratory data, 

is observed in the field. Additionally, it could be used to determine vulnerability of different areas. 

Data to refine inputs to PRZM-GW may be used to refine modeling estimates of groundwater 

concentrations. Studies may involve understanding sorption or degradation in subsurface 

environments. It is recommended that a protocol be submitted, prior to conducting any of these 

studies. In the absence of more suitable inputs or scenarios, estimated environmental 

concentrations (EECs) generated from PRZM-GW in the same fashion as estimated drinking water 

concentrations (EDWCs) for groundwater used as drinking water, will be used to characterize risks 

to terrestrial plants from residues in irrigation water obtained from groundwater sources. 

• The ecological database is also incomplete based on the ecological effects data requirements outlined 

in the 40CFR158 Subpart G3

. 

o Data are needed for the following studies on a representative Typical End-Use Product (TEP) 

that contains i) aminopyralid and 2,4-D; ii) aminopyralid and triclopyr; iii) aminopyralid and 

clopyralid; iv) aminopyralid and metsulfuron; and v) aminopyralid and fluroxypyr-1-

methylheptyl ester. 

o Freshwater invertebrate acute toxicity (OCSPP 850.1010) 

o Tier II Terrestrial plant vegetative vigor (OCSPP 850.4100) and seedling emergence 

(OCSPP 850.4250) including soybean, lettuce, and onion 

o Aquatic plant growth (freshwater diatom, Navicula pelliculosa) (Tier II) (OCSPP 

850.4500) 

Additionally, an aquatic plant growth study for cyanobacteria (OCSPP 850.4550) is needed using 

a representative product that contains aminopyralid only. 

Finally, EFED is requesting a non-standard study (OECD 237) to assess aminopyralid TGAI 

toxicity to developing bee larva. 

• Section 3 of this document discusses information on labels that are needed to reduce uncertainty in risk 

assessments. These uncertainties include labels that do not have maximum single application rates, 

maximum annual application rates, and/or minimum retreatment intervals. Many of these 

uncertainties apply to uses on trees and in forested areas. Additionally, some labels include very broad 

use sites such as “non-crop areas” and various areas that could be considered aquatic use sites, i.e., 

direct applications to water. 

2. Introduction 

Aminopyralid is a systemic synthetic auxin analogue in the pyridine carboxylic acid (also known as 

picolinic acids) class of herbicides and functions as a plant growth regulator (Ware and Whitacre, 2004; 

 

3

 CFR. 2013. Title 40 (Protection of the Environment), Chapter 1 (Environmental Protection Agency), Subchapter E (Pesticide 

Programs), Part 158 (Data Requirements for Pesticides), Subpart G (Ecological Effects) http://www.ecfr.gov/cgi-bin/textidx?c=ecfr&SID=ff5c7fef3645e7cd5abceca0b597bccb&rgn=div6&view=text&node=40:25.0.1.1.9.7&idno=40 
Page 4 of 63 

Wood, 2013). The compound has been registered in the United States for use in controlling annual and 

perennial broadleaf weeds since 2005. 

EFED evaluated the most recent ecological risk assessments for aminopyralid in association with any 

available updated toxicity, exposure, and usage information to determine if sufficient data are available or 

if further updates are needed to support Registration Review. Recent risk assessments include the 2010 

EFED risk assessment of aminopyralid which reviewed the use of aminopyralid in forests, non-cropland, 

grazed areas, and industrial non-crop areas in Arkansas (USEPA, 2010a, D383620). No new uses have 

been assessed since that time. Additionally, a data screen for proposed new uses directly to water was 

conducted (USEPA, 2013, D410811). EFED has also considered the latest Agency science policies and 

risk assessment methodologies in compiling this problem formulation. 

3. Use Characterization 

Aminopyralid is formulated as an emulsifiable, flowable, soluble concentrate, and as water dispersible

granules in multiple end-use products. Aminopyralid is registered for use on a variety of agricultural, 

forest, commercial, and residential areas and may be applied via aircraft, ground sprayer, hand-held 

sprayer, and boom sprayer. Aminopyralid may also be applied to forest plantings via broadcast, high 

volume spray, spot treatment, stump treatment, girdle treatment, frill treatment, tree wound treatment, and 

tree injection. Currently, there are 15 active Section 3 registrations for aminopyralid including its salt 

forms and 36 Special Local Needs (SLN; Section 24c) registrations (Table 1). Twelve products 

containing aminopyralid include multiple active ingredients. Aminopyralid TIPA salt occurs in 

combination with: 

• TIPA salt of 2,4-D (PC code 030035; 2,4-dichlorophenoxyacetic acid, triisopropanolamine salt), 

• 2,4-D dimethylamine salt (PC code 030019; 2,4-dichlorophenoxyacetic acid dimethylamine salt), 

and 

• triclopyr triethylamine salt (PC Code 116002; N,N-diethylethanamine;2-(3,5,6-trichloropyridin-2-

yl)oxyacetic acid)). 

Some aminopyralid potassium salt products also contain the active ingredients metsulfuron (PC code 

122010; 2-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)carbamoylsulfamoyl]benzoic acid)) and clopyralid (PC

code 117403; 3,6-dichloro-2-pyridinecarboxylic acid). One product containing aminopyralid is combined

with fluroxypyr 1-methylheptyl ester (PC code 128968; 1-methylheptyl (4-amino-3,5-dichloro-6-fluoro-2-

pyridyloxy)acetate). Details on the percent active ingredients in currently registered products are provided 

in Appendix A. Clopyralid, 2,4-D, triclopyr, and fluroxypyr-1-methylheptyl ester have the same mode of 

action as aminopyralid (i.e., mimicking natural auxins and serving as plant growth regulators) (HRAC, 

2005). Metsulfuron is a sulfonylurea and inhibits branched chain amino acid biosynthesis through the 

inhibition of the enzyme acetaolactate synthetase, i.e., ALS inhibitor (Ware and Whitacre, 2004). 

Table 1. Number of national (Section 3) and Special Local Needs (SLN; Section 24c) registrations for 

aminopyralid acid and its salts. 

Active 

Ingredient 

Number of 

National 

Registrations 

Number of SLN -

Registrations (states with 

registrations) 

Number of products with Multiple 

active ingredients, other active 

ingredients 

Aminopyralid 

TIPA salt 9 32 (AL, CA, FL, GA, HI, LA, MN, MS, NC, SC, TX, VA) 

8 products, 

2,4-D TIPA salt, 

2,4-D dimethylamine salt 

Triclopyr Trielthylamine salt 

Aminopyralid 

Potassium salt 4 3 (ID, OR, WA) 

3 products, 

Metsulfuron, 

Clopyralid 

Aminopyralid 

acid 2 1 (FL) 1 product, 

Fluroxypyr 1-methylheptyl ester 
Page 5 of 63 

Aminopyralid (acid and salts) is registered for use on corn, wheat, grasses, pastures, rangeland, ditch 

banks, swamps, flood plain, marshes, conservation reserve program land, non-crop areas, campgrounds, 

recreational areas, roadsides, rights-of-ways, trails, industrial sites, nonagricultural areas, forest lands, 

aquatic areas, recreational areas, forest plantations, conifers, and deciduous trees. The maximum single 

and annual application rate reported is 0.86 lbs potassium salt /A or 0.73 lbs acid equivalents (a.e.)/A. 

In 2013, a proposal for a Section 3 new use of using aminopyralid for control of broadleaf and woody 

plants and annual grasses (knotweeds (Japanese, Bohemian, and others), purple loosestrife, tropical soda 

apple, Japanese stiltgrass, Canada thistle, and Pennsylvania smartweed) in aquatic sites was submitted. 

The proposed labels define aquatic sites as “non-irrigation ditch banks, seasonally dry wetlands such as 

flood plains, deltas, marshes, swamps, or bogs, transitional areas between upland and lowland sites as

well as along shorelines and shallow areas of still and moving water sites.” The submission is currently 

under review. 

The Screening Level Usage Analysis (SLUA) conducted by the Biological and Economic Analysis 

Division (BEAD) estimates the following agricultural uses during 2004-2011 (USEPA, 2013b): 

• pasture 90,000 lbs acid equivalent (a.e.), 

• wheat 1,000 lbs a.e. 

• fallow land <500 a.e.. 

• corn <500 a.e. 

The percent crop treated estimates were all less than 2.5%. The SLUA analysis is only applicable to 

agricultural uses; therefore, non-agricultural usage (including residential, forest, and industrial 

applications) of aminopyralid is not captured in the SLUA. 

The chemical profile produced by BEAD, located in the docket, lists the use patterns associated with active 

registrations of aminopyralid. EFED will rely on the BEAD chemical profile when estimating 

environmental exposures that result from these registered uses. Additionally, in order to be protective, 

EFED will utilize the use information that results in maximum exposure (e.g., concentration) estimates for 

a given use pattern for the drinking water and ecological risk assessments. If the labels (and consequently 

the BEAD chemical profile) do not include all information needed to enable estimation of maximal 

exposures, such as the maximum single application rate, minimum application interval, annual maximum 

rate allowed (lbs a.i. or a.e./year), and application method, EFED will make conservative assumptions 

regarding these use parameters. 

Some use patterns are not sufficiently characterized to permit ready calculation of a maximum application 

rate per acre, or else involve very broad use sites. More information on the following items would reduce 

uncertainty regarding such uses in the risk assessment: 

• Some labels have instructions for applications to trees (cut surface, cut-stump treatment, tree injection, 

hack and squirt treatment, and frill and girdle method). The label should specify the maximum amount 

of aminopyralid that may be applied per tree (e.g., as a function of trunk diameter), as well as the

maximum number of trees that may be treated per acre. This is because maximum application rates 

(both single and total annual) in lbs a.i or a.e./A are needed in order to model exposures resulting from 

these types of uses. Additionally, the maximum number of applications per year and minimum 

retreatment interval should be specified for these uses. 

• The labels have several nonspecific use sites. These broadly-categorized use sites will require EFED 

to employ the assumption that aminopyralid can be used at a broad range of agricultural, commercial, 

residential, and forest sites. These use sites will also necessitate the assumption that application may 

occur to both aquatic and terrestrial environments. The following are examples of nonspecific use 

sites: 
Page 6 of 63 

o non-irrigation ditch banks, seasonally dry wetlands (such as flood plains, deltas, marshes, 

swamps, or bogs), transitional areas between upland and lowland sites when dry, ditchbank 

weeds, shoreline weeds, non-cropland areas, and natural areas. 

The Agency encourages that use site descriptions be made as specific as possible, so that potential use 

areas are not broader than necessary. Vague use site descriptions can impact assumptions made when 

doing proximity analysis for determinations on the potential risks to federally listed 

threatened/endangered (hereafter referred to as “listed”) species. 

• Some restrictions are specified on a product basis rather than on an active ingredient basis. 

• Some labels only include a maximum single application rate. They do not include a maximum annual 

or seasonal application rate, maximum number of applications, or minimum retreatment interval (see 

the EFED label Data Report for 005209). 

• Some labels with multiple active ingredients, where acid equivalents are relevant, provide acid 

equivalent restrictions but do not specify to which active ingredient the limitations apply. 

4. Conclusions from Previous Risk Assessments 

a. Ecological Risk Assessment 

Four previous risk assessments have been completed for aminopyralid (including salt and acid forms): a

reduced risk assessment in 2004 (USEPA, 2004, D306647); a new use assessment in 2005 (USEPA, 2005, 

D301682) and a new use assessment in 2009 (USEPA, 2009, D361924); and a Section 24C Special Local 

Needs Assessment in 2010 (USEPA, 2010a, D383620). The uses evaluated in the risk assessments 

include: field corn, corn grown for ensilage, wheat, pasture/rangeland, industrial vegetation, roadsides, 

rights-of-way, conifer forest site preparation, conifer release, mid-rotation understory brush and weed 

control in loblolly, slash, shortleaf, and longleaf pine stands, and control of herbaceous and woody plants 

in forests, non-cropland, grazed areas, and industrial non-crop areas. All of the risk assessments found 

potential for direct risk to listed and non-listed terrestrial plants. Due to potential direct adverse effects on 

terrestrial plants, indirect effects to all listed aquatic and terrestrial plants and animals could occur. In 

addition to direct risk to terrestrial plants due to transport via spray drift and runoff to adjacent areas, 

previous assessments have highlighted exposure pathways of residues in irrigation water (including 

groundwater) and compost (manure and plant material). Incident data have reported adverse effects to 

terrestrial plants exposed to aminopyralid in residues in hay and manure used in composting. Also, due to 

aminopyralid’s persistence and mobility, it may leach to groundwater and/or move into surface water 

through runoff. 

Because aminopyralid in both salt and acid forms dissociates readily in water to release the aminopyralid 

anion, and ecotoxicity data were similar for aminopyralid salts and aminopyralid acid, EFED bridged the 

ecotoxicity data studies for aminopyralid salts with aminopyralid acid. In other words, exposure was 

estimated for aminopyralid acid, and toxicity data were expressed in terms of acid equivalents for the risk 

assessment. 

The major environmental fate and ecological risk conclusions identified in previous assessments are 

summarized in Table 2 and 3. 

Table 2. Potential for direct effects identified in previous assessments for aminopyralid1

Listed/or 

non-listed Birds2 Mammals Terrestrial Invertebrates 

Aquatic 

Vertebrates3

Aquatic 

Invertebrates 

Terrestrial 

Plants 

Aquatic 

Plants 

Non-listed --* -- -- -- -- Yes --

Listed -- -- -- -- -- Yes --

-- = Risk below LOC; * indicates a full data set is not available 

1 Risk concerns were identified when the RQ exceeded the corresponding level of concern in a previous risk assessment or were identified 

as a potential concern based on weight of evidence.

2 Birds serve as surrogates for terrestrial-phase amphibians and reptiles. 
Page 7 of 63 

3

Fish serve as surrogates for aquatic-phase amphibians. 

Table 3. Potential environmental fate concerns identified in previous assessments for aminopyralid 

Bioconcentration/ 

Bioaccumulation1

Groundwater 

Contamination2 Sediment Persistence Residues of Concern Volatilization 

No,

log Kow<3 Yes2 No Yes

Aminopyralid acid 

and Unextracted 

Residues

No

1 Based on whether previous assessments indicated this was a risk concern or if previous assessments ran Kow Based Aquatic Bioaccumulation 

Model (KABAM) for chemicals with a log Kow >3. 

2 Previous risk assessments indicated that aminopyralid has the potential to reach groundwater; however, it did not result in drinking water 

concentrations high enough to cause a concern for human health. However, residues could be high enough to present a risk to terrestrial plants 

exposed to irrigation water. Aminopyralid residues may also be transported to surface water via spray drift, run-off, and erosion. Screening level 

Estimated Drinking Water Concentrations (EDWC) in surface water have not been high enough to cause concern for human health; however, they 

have been high enough to result in a concern for the potential effects to terrestrial plants via exposure to aminopyralid residues in irrigation water. 

b. Drinking Water Exposure Assessments 

The most recent drinking water assessment was completed in 2010 (USEPA, 2010b, D383620) and the 

estimated drinking water concentrations (EDWCs) for human health risk assessment are shown in Table 4. 

The Health Effects Division (HED) determined that the residue of concern for aminopyralid in terms of 

human health was aminopyralid anion (USEPA, 2005b, D301689). Unextracted residues were also 

considered a residue of concern in the drinking water assessments because a range of polar and nonpolar 

solvents were not explored to determine if the amount of unextracted residues could be decreased and the 

identity of the unextracted residues is unknown. In 2010, surface- and groundwater-based EDWCs for 

aminopyralid were well below the level of concern (LOC) for human health). Because EFED has recently 

implemented revised percentage crop area (PCA) factors, and introduced the Pesticide Root Zone ModelGroundWater (PRZM-GW) model to determine EDWCs in groundwater, an updated drinking water 

assessment will be completed. The HED will likely conduct a new dietary exposure and risk assessment if 

there are significant changes from previously-calculated EDWCs. 

Table 4. Tier I EDWCs for drinking water risk assessment based on aminopyralid use at 0.11 lbs 

a.e./acre/year for forest uses. 

Source of 

Drinking Water 

Aminopyralid acid (including unextracted residues) concentration in drinking 

water (μg/L) 

Acute Annual Average 

Surface water 11.4 μg/L 2.19 μg/L 

Groundwater 6.43 

c. Clean Water Act Programs 

Aminopyralid is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act.4

 No Total Maximum Daily Loads (TMDL) or section 304(a) 

ambient water quality criteria have been developed for aminopyralid.5 Aquatic life benchmarks6 have 

been established for aminopyralid; however, any data submitted or otherwise located as part of the 

Registration Review process that indicate greater sensitivity than data currently available may be used to 

revise aquatic life benchmarks if applicable. 

 

4

 Specific state causes of impairment that make up the national pesticides cause of impairment group are listed at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885. 

5

 Specific state pollutants that make up the National Pesticides Pollutant Group and have TMDLs are listed at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_gr

oup_name=PESTICIDES. 

6

 Aquatic Life Benchmarks are available at (http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm.
Page 8 of 63 

5. Environmental Fate and Transport 

Under most environmentally relevant conditions, aminopyralid will exist in an ionic form. The acid log 

dissociation constant (pKa of 2.56) indicates that greater than 97% of the compound will be in the anionic 

(negatively charged) form at environmentally-relevant pH ranges (pH 4.0-9.0), regardless of the original 

molecular species. This shows that in water the chemical of relevance in terms of organism exposure is 

the aminopyralid anion. All environmental fate studies were conducted on aminopyralid acid (PC Code 

005100) unless otherwise specified; aquatic exposure was estimated in terms of acid equivalents in 

previous assessments. 

Aminopyralid is relatively soluble (203 – 212 g/L at 20oC) and is classified as mobile to highly mobile 

based on measured Koc values (USEPA, 2010). It has the potential to reach groundwater, especially in 

vulnerable soils with low organic-carbon content and/or the presence of shallow groundwater. This is 

supported by the leaching observed in some terrestrial field dissipation studies in which aminopyralid was 

measured at up to 90 cm depth in the soil, which was the lowest depth sampled. This ensued when a rain 

event occurred close to the time of application. Aminopyralid may also be transported to surface water via 

runoff and spray drift. While it may be found in both water and sediment, the octanol-water partition

coefficient (KOW) and organic-carbon normalized soil-water distribution coefficient (KOC) values are much 

lower than the values that would trigger the need to request sediment toxicity studies (40 CFR Part 

158.630).7 Compounds with a log KOW of three and above are generally considered to have the potential to 

bioconcentrate in aquatic organisms. Based on log KOW’sranging from -2.96 to -1.76, aminopyralid is not 

likely to bioconcentrate in organisms. Aminopyralid is classified as non-volatile from water, dry nonadsorbing surfaces, and moist soil (USEPA, 2010). The estimated octanol-air partition coefficient (KOA) 

value is 3.88 × 10-15, and aminopyralid is not likely to accumulate in terrestrial organisms.8 

Fate study results indicate that aminopyralid may range from non-persistent to very persistent in the 

environment.9 Aminopyralid is stable to hydrolysis at pH 5, 7, and 9 and essentially stable to anaerobic 

aquatic metabolism. Aminopyralid is degraded by aerobic metabolism in soils (half-lives ranged from 15 

to 148 days at 20oC in eight soils). Unextracted residues made up a maximum of 24% of applied 

radioactivity in the aerobic soil metabolism studies, and it is unknown what percentages of those residues 

were comprised of parent aminopyralid. Therefore, half-lives were also estimated assuming that the 

unextracted residues were aminopyralid, as done in previous aminopyralid ecological and drinking water

assessments. Aerobic soil metabolism half-lives for aminopyralid plus unextracted residues ranged from 

31 to 193 days at 20°C in the same eight soils. The aerobic aquatic metabolism half-lives are uncertain 

because aerobic environments were not maintained throughout the study. As anaerobic metabolism is 

expected to be slower than aerobic metabolism, the half-lives from the available aerobic aquatic study are 

expected to be conservative. Aminopyralid is likely to be degraded via aqueous photolysis in clear water 

and on moist leaf surfaces (aqueous photolysis half-life = 0.6 days). 

Dissipation half-lives in reviewed terrestrial field dissipation studies ranged from 24 to 36 days at two sites 

in the United States. Dissipation half-lives reported in as-yet unreviewed terrestrial field dissipation 

studies ranged from 9 to 54 days at six sites in the United States and Canada. Time to 90% dissipation 

(DT90) ranged from 40 to 430 days. Carryover of residues was minimal at six sites (carryover ranged from 

 

7

 Sediment data may be required if the soil-water distribution coefficient (Kd) is ≥ 50 L/kg, KOCs are ≥1000 L/kgorganic carbon, and the log KOW is ≥ 3 (40 CFR Part 158.630). Sediment data may also be requested if there may be 

a toxicity concern. 

8

 A recent FIFRA Scientific Advisory Panel (SAP) reported, “Gobas et al (2003) concluded that chemicals with a log 

KOA greater than five can biomagnify in terrestrial food chains if log KOW greater than two and the rate of chemical 

transformation is low. However, further proof is needed before accepting these limits without reservations” (USEPA, 

2009c). This was also supported by the work of Armitage and Gobas 2007. 

9

 Chemicals with half-lives greater than 60-days in soil, water, and sediment are classified as persistent and chemicals 

with half-lives greater than 180 days are classified as very persistent (USEPA, 2012a). 
Page 9 of 63 

0 to 2.7% at these sites after 121 to 372 days); however, carryover was higher (5.7% after 121 days and 

6.2% after 455 days) at two sites. Aminopyralid’s half-lives based on aminopyralid residues alone suggest 

that aminopyralid will not accumulate with successive applications; however, those that include 

unextracted residues indicate it may accumulate in some soils with successive applications. Overall, these 

results indicate that in some environments, aminopyralid does persist while in others it is less persistent. 

Additionally, incidents demonstrate that aminopyralid residues may be present at phytotoxic levels in 

composted manure. While most residues in terrestrial field dissipation studies remained in the top soil 

layer, residues were detected in the lowest depth (90 cm) sampled in one study when it rained within a few 

days of the application. This supports the analysis that aminopyralid has the potential to leach to 

groundwater in some environments. 

Two aquatic field dissipation studies have been completed. In one study, aminopyralid was broadcast 

along shorelines of a class 2 stream in Oregon (Strahler stream order classification system) and a manmade canal in Florida for 225-foot and 15-ft swath widths (12-ft of shoreline and 3-ft into waterbody)

(MRID 48939201) at an application rate of 0.11 lbs a.e./A. Aminopyralid concentrations were monitored

within the treated area, and at upstream and downstream locations. Maximum concentrations of 

aminopyralid observed in this study were 33 μg/L-water, 15 μg/kg-sediment in a sample collected 8 days

after application, and 333 μg/kg-soil in a sample collected 1-hour after application. Detections in sediment 

were sporadic with most detections below 1 μg/kg-sediment. Dissipation half-lives were not calculated for 

data from the flowing water bodies. Residues in water were transported rapidly from the treated area. 

In the other aquatic field dissipation study, aminopyralid was broadcast at 0.036 lbs a.e./A10 to the 

perimeter of two ponds (0.4 to 0.7 acre) in Texas and two ponds in Indiana (MRID 48939202). The target 

water concentration was 40 μg a.e./L. Caged catfish (Ictalurus sp.), sunfish (Lepomis macrochirus), clam 

(Unionoida, species not reported), and crayfish (Cambaridae sp.) were exposed and residues were 

measured. Some species were not fully identified in the study. Maximum aminopyralid concentrations 

observed in water and tissue are reported in Table 5. The maximum aminopyralid concentration observed 

in sediment was 4.4 μg/kg-sediment. Aquatic dissipation half-lives ranged from 10.8 to 14.6 days. Visible 

light penetration was reportedly 30 to 31 inches. The sites were characterized as eutrophic and having a 

high level of biological productivity. Most UV-b light (86% was extinguished below this depth) was 

available in the top 2 inches of the water column. The majority of photolytic activity occurred in the top 

12 inches of the water column. The short half-lives observed may be related to the rapid aqueous 

photolysis rate of aminopyralid and would not likely occur in areas where light penetration is minimal. 

A selection of environmental fate and transport properties of aminopyralid is summarized in Table 5. 

Table 5. Chemical Properties and Environmental Fate Parameters of Aminopyralid Acid (unless Otherwise

Specified) 

Parameter Value Description/Comments1,2 Source

Selected Physical/Chemical Parameters 

PC Code 005209 (TIPA Salt) 

005100 (acid) 

005219 (potassium salt) 

-- -- 

Molecular Mass 207.02 g/mol (acid) 

398.27 g/mol (TIPA salt) 

245.12 g/mol (potassium salt) 

-- -- 

Molecular Formula C6H4Cl2N2O2 (acid) -- -- 

Vapor pressure oC Torr Pa Not expected to volatilize from dry MRID 46235701 

 

10 This is a lower rate than that proposed for aquatic sites of 0.22 lbs a.i./A for spot treatments and 0.11 lbs a.i./A for 

broadcast and ground treatments.
Page 10 of 63 

Parameter Value Description/Comments1,2 Source

20 7.14×10-11 9.52×10-9

surfaces.2 Will vary with pH. 

25 1.94 × 10-10 2.59×10-8

Aqueous solubility 

(20oC) 

pH mg/L 

Soluble, will vary with pH. 

MRID 46235701 5 212,000 

7 205,000 

9 203,000 

Henry’s Law Constant 

(20°C; pH 7) 9.5 x 10-17 atm-m3

/mol 

Not expected to volatilize from water 

or moist/wet soil surfaces.2 Will vary 

with pH. 

Estimated from vapor 

pressure 

and water solubility at 

pH 7 and 20oC.1

Dissociation Constant 

pKa (20oC) 2.56 at 20oC 

Compound is a strong acid and will 

exist mainly in the dissociated form at 

most environmental pH values. As an 

anion, it will behave differently at 

various pH levels. 

MRID 46235701 

Log octanol-to-water 

partition coefficient 

(Log KOW) (19oC) 

pH Log KOW

Will vary with pH. MRID 46235701 

5 -1.76 

7 -2.87 

9 -2.96 

Persistence3

Hydrolysis half-life Stable (pH 5, 7, 9; 20 oC and 

50oC) Does not hydrolyze. MRID 46235726 

Atmospheric Half-life 6.4 days (estimated) EPIWeb4.1, Appendix 

C 

Aqueous photolysis 

half-life (20°C) 

0.6 days(pH 5)4 May photolyze in clear, shallow 

waters. Adjusted for sunlight intensity 

at 40°N latitude. 

MRID 46235727 

Soil photolysis halflife (25°C) 72.2 days (pH 7.7)5 Adjusted for sunlight intensity at 40°N 

latitude. MRID 46235728 

Aerobic soil 

metabolism half-life 

(10-30°C) 

pH, oC Acid

Acid plus 

unextracted 

residues 

Not persistent to very persistent3 in 

eight soils. One soil was tested at 

multiple temperatures. 

MRID 462357298

Holdrege8

4.6, 25 42.0 58.2 

Thessaloniki

7.7, 20 26.4 46.5 

MRID 479112019

Cuckney 

5.6, 20 147.5 192.5 

Charentilly

5.8, 20 28.9 41.3 

Parabraun 

7.7, 20 86.6 126 

Parabraun 

7.7, 10 408 -- 

Parabraun 

7.7, 30 107 -- 
Page 11 of 63 

Parameter Value Description/Comments1,2 Source

Calloway 

6.6, 20 133.3 192.5 

MRID 47925801 Fillmore 

5.0, 20 92.4 141.5 

Albany 

4.6, 20 14.7 31.1 

Anaerobic soil 

metabolism half-life No Data -- -- 

Aerobic aquatic 

metabolism half-life 

(20°C) 

pH Half-life (days) 

Not a rapid degradation pathway (very 

persistent3). Aerobic environment was 

not maintained throughout the entire 

study. 

MRID 46235731 

5.9 866 

7.9 990 

8.2 462 

Anaerobic aquatic 

metabolism half-life 

(20-26°C) 

Stable (2 systems) Not a rapid degradation pathway (very 

persistent3). MRID 46235730 

Mobility7

Solid-water 

distribution coefficient 

(Kd) in L/kg-soil 

(25oC) 

Organic-carbon 

normalized 

distribution coefficient 

(KOC) in L/kg-oc 

Freundlich solid-water 

distribution coefficient 

(KF) and Freundlich 

Exponent (1/n) 

pH Kd Koc KF 1/n Compound will exist primarily in 

dissociated form (as an anion) at most 

environmental pHs, and mobility may 

vary greatly with pH and other soil 

properties. 

The relative standard deviation for Kd

values (132%) was higher than the 

relative standard deviation for Koc

values (95%). While outliers were 

present, in general, KOC values 

decreased with increasing pH. There 

was not a consistent trend with Kd

values and pH. 

MRID 46235732 

7.5 0.03 1.05 0.01 0.32 

7.8 0.04 4.49 0.04 0.79 

6.9 0.04 2.33 0.04 1.31 

6.6 0.07 4.59 0.05 0.75 

6.1 0.08 7.54 0.07 0.82 

4.5 0.15 24.3 0.13 0.86 

7.8 0.29 7.39 0.26 0.87 

4.8 0.72 19.95 0.73 0.90 

Field Dissipation

Terrestrial field 

dissipation half-life; 

leaching depth 

State/ 

Province

Half-life 

(days) 

Max 

leaching 

depth (cm) Bare ground studies. Carryover from 

year to year was not expected. MRID 46235734 

MS 34 15 

CA 26 75 

NB 21 15 

Bare ground studies. Broadcast at 150 

g a.e./ha. Under review. Carryover of 

residues ranged from 0% to 6.2% of 

applied. In one study, 6.2% of applied 

was present after 455 days after 

application. 

MRID 46235735 

ON 31 45 

MB 30 30 

SK 9 15 

MT 35 90 

AB 54 15 

Aquatic field 

dissipation half-life State

Max Aminopyralid 

Concentration 

Broadcast along shoreline for 225-foot 

and 15-ft swath width (12ft of 

shoreline and 3ft into waterbody) of 

flowing waterbody. Application rate 

MRID 48939201 

Water 

μg/L 

Sed. 

μg/kg 

Soil 

μg/kg 
Page 12 of 63 

Parameter Value Description/Comments1,2 Source

OR 32.9 14.9 333 was 0.11 lbs a.e./A. 

FL 32.3 1.13 115 

State

Max 

DT50 

(days)

Max 

Aminopyralid 

Concentration 

Broadcast at 0.036 lbs a.e/A to ponds. 

Caged catfish, sunfish, clam, and 

crayfish were exposed and residues 

were measured. Max aminopyralid 

concentration in sediment was 4.4 

μg/kg. 

Water MRID 48939202 

μg/L 

Tissue 

μg/kg 

TX 14.6 198 6.8 

IN 12.9 114 30.1 

Fish Bioconcentration

Fish bioconcentration 

factors (steady-state); 

depuration rate 

No data. -- -- 

Analytical Methods 

ECM/ILV: Water 

Acidify>SPE extraction with 

derivitization 

Detection with HPLC/MS/MS 

(Method GRM 01.32) 

Aminopyralid LOD 0.01 μg/L and 

LOQ = 0.05 μg/L 

MRIDs: 46235601 

(ECM), 46235713 

(ILV) 

Acidify>SPE extraction with 

derivitization 

Detection with HPLC/MS/MS 

Aminopyralid LOQ=0.05 μg/L MRID 47572602 

(ECM) 

ECM/ILV: Soil 

Shake in methanol/2 N sodium 

hydroxide (90:10) solution> SPE 

Detection with HPLC/MS/MS 

Aminopyralid LOQ = 0.001 μg/g MRID 47572602 

(ECM) 

Shake 2x in acetonitrile/1 N 

hydrochloric acid 

(90:10)>dry>reconstitute in 1 N 

HCl> 96-well SPE 

plate>derivatization 

Detection with HPLC/MS/MS 

(Method GRM 2.34) 

Aminopyralid LOQ=0.0015 μg/g MRIDs: 46235602 

(ECM), 46235715 

(ILV) 

Storage Stability Aminopyralid stable in soil at -

20oC for 194 days. 

Not reviewed MRID 46235720 

Spray Drift -- Not reviewed MRID 46235834 

1All estimated values were estimated according to “Guidance for Reporting on the Environmental Fate and Transport 

of the Stressors of Concern in Problem Formulations for Registration Review, Registration Review Risk Assessments, 

Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other Relevant Risk Assessments” 

(USEPA, 2010). 

2Volatility classifications are based on classifications on the Terrestrial Field Dissipation Guideline OCSPP 835.6100 

(USEPA, 2008). 

3Degradation kinetics were calculated using the single first order decay equation using either nonlinear regression of 

non-transformed data or linear regression of log-transformed data. Persistence classification are based on criteria 

established for the Toxic Release Inventory, which considers chemicals persistent if the half-life in water, soil, or 

sediment is greater than 60-days and very persistent if the half-life is greater than 180-days (USEPA, 2012a). A 

half-life in air greater than 2-days is also considered persistent. 

4 Supplemental because not all transformation products present at greater than 10% applied radioactivity were 

identified and quantified. 

5

 Supplemental because total recovery was 85% at study termination. Unextracted residues were a maximum of 8%. 
Page 13 of 63 

6

 Studies were considered supplemental due to a low mass balance, or due to the presence of unextracted residues at 

greater than 10% applied radioactivity. Unextracted residues were up to 24% applied radioactivity in one study. 

7

 Mobility classifications are based on Food & Agriculture Organization of the United Nations (FAO) Mobility 

criteria (FAO, 2000; USEPA, 2006). 

8

 DT50 were measured at 60 and 120 g/ha application rates. The highest DT50 of the two is reported. 

9

 Conducted on foreign soils from Greece, France, Germany, and the United Kingdom. 

Based on the available studies, the main uncertainties in the environmental fate database are 1) aerobic 

aquatic metabolism half-lives; 2) identity of the unextracted residues in fate studies; and 3) the identity of 

the major degradates in the aqueous photolysis study

11. Previously, conservative assumptions (e.g., using 

the aerobic aquatic metabolism half-lives for systems where an aerobic environment was not maintained 

and assuming the unextracted residues were the parent), did not result in a risk concern for most taxa. 

However, previously completed assessments for aminopyralid (USEPA, 2005, D301682, 2009, D361924, 

2010a, D383620), indicated a risk of concern for use of surface and/or groundwater-derived irrigation 

water and potential risk to terrestrial plants. 

a. Transformation Products 

The only major degradates (e.g., those present at greater than 10% applied radioactivity) of aminopyralid 

were observed in the aqueous photolysis study (MRID 46235727) and were identified as oxamic acid 

(CAS#471-47-6) and malonamic acid (CAS# 2345-56-4), plus unidentified 2-3 carbon chain degradates. 

Maximum amounts of oxamic acid and malonamic acid were not reported but evidence suggests they were 

present, along with four other residues, at a maximum amount of 69 percent applied radioactivity. No 

environmental degradates other than CO2 were observed in the remaining fate studies (USEPA, 2005). 

According to HED, neither oxamic acid nor malonamic are considered residues of concern; both chemicals

are small amino acid analogs and are expected to be readily metabolized and/or rapidly excreted following 

uptake without any significant biological effects. The structures of identified residues are listed in Table 

6. Appendix D provides details on the maximum amount of various residues observed in fate studies. 

Table 6. Structures of Aminopyralid and Its Environmental Transformation Products 

Code Name/ Synonym/ 

Chemical Name/ Formula/MW/ SMILES Chemical Structure 

Aminopyralid, XDE-750 

IUPAC: 4-amino-3,6-dichloropyridine-2-

carboxylic acid 

CAS: 4-amino-3,6-dichloro-2-

pyridinecarboxylic acid 

CAS Number: 150114-71-9 

SMILES: Clc1c(nc(Cl)cc1N)C(=O)O 

PC Code: 005100

Aminopyralid TIPA salt 

CAS Number: 566191-89-7 

2-Pyridinecarboxylic acid, 4-amino-3,6-

dichloro-, compd. with 1,1',1''-nitrilotris[2-

propanol] 

PC Code: 005209

 

11 While a couple of degradates were identified in the aqueous photolysis study, there were four unidentified 

degradates that may have been major degradates. Additionally, the amount of oxamic acid and malonamic acid 

formed is not reported in the study. 
Page 14 of 63 

Code Name/ Synonym/ 

Chemical Name/ Formula/MW/ SMILES Chemical Structure 

Aminopyralid potassium salt 

CAS Number: 566191-87-5 

2-Pyridinecarboxylic acid, 4-amino-3,6-

dichloro-, monopotassium salt 

PC Code: 005219

Oxamic Acid 

CAS number: 471-47-6

SMILES: C(=O)(C(=O)O)N

Malonamic acid 

CAS Number: 2345-56-4 

SMILES: C(C(=O)N)C(=O)O

6. Receptors 

Table 7 and Table 8 provide a summary of the most sensitive acute and chronic toxicity values for 

aminopyralid across aquatic and terrestrial taxonomic groups, respectively. Based on the available 

ecotoxicity information, aminopyralid is slightly to practically non-toxic to freshwater and estuarine fish 

and aquatic invertebrates, birds, mammals, and terrestrial insects on an acute exposure basis. Since no data 

are available specific to aquatic-phase amphibians, freshwater fish are used as surrogates. Since no data are 

available for reptiles or terrestrial-phase amphibians, birds serve as a surrogate for these taxa. As expected 

for an herbicide, aquatic and terrestrial plants, particularly dicotyledon species, are relatively sensitive to 

aminopyralid. 

a. Effects to Aquatic Organisms 

Table 7. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Technical 

Aminopyralid 

Taxonomic 

Group 

Study 

Type Surrogate Species 

Toxicity Value 

(all units in terms 

of acid equivalents) 

Acute Toxicity 

Classification Source 

(MRID) 

Freshwater fish* 

Acute 

Rainbow Trout 

(Oncorhynchus 

mykiss) 

LC50 = >100 mg/L Practically nontoxic 462358-14 

Acute

Bluegill sunfish 

(Lepomis 

macrochirus) 

LC50 = >100 mg/L Practically nontoxic 462358-15 
Page 15 of 63 

Taxonomic 

Group 

Study 

Type Surrogate Species 

Toxicity Value 

(all units in terms 

of acid equivalents) 

Acute Toxicity 

Classification Source 

(MRID) 

Chronic 

Fathead minnow 

(Pimphales 

promelas) 

NOAEC = 1.36 

mg/L 

LOAEC = 2.44 

mg/L based on 

decreased post-hatch 

survival and 

sublethal 

effects(Early Life 

Stage Toxicity) 

-- 462358-21 

Freshwater 

invertebrates 

Acute Stonefly 

(Pteronarcys sp.) EC50 = 15 mg/L Slightly toxic 400946-02 

Chronic Waterflea (Daphnia 

magna) 

NOAEC = 102 mg/L 

LOAEC > 102 mg/L

 (Full Life Cycle)

-- 462358-22 

Estuarine/marine 

fish 

Acute 

Sheepshead minnow 

(Cyprinodon 

variegates) 

LC50 > 120 mg/L Practically nontoxic 462358-20 

Chronic 

Sheepshead minnow 

(Cyprinodon 

variegates) 

NOAEC = 0.096 

mg/L 

LOAEC = 0.201 

mg/L based on 

delayed time to 

hatch 

-- 489392-04 

Estuarine/marine 

shrimp Acute Mysid (Americamysis bahia) LC50 > 100 mg/L Practically nontoxic 462358-19 

Estuarine/marine 

mollusk Acute 

Eastern oyster shell 

deposition 

(Crassostrea 

virginica) 

LC50 > 89 mg/L 

Slightly toxic or 

Practically nontoxic 462358-18 

Estuarine/marine 

invertebrate Chronic Mysid (Americamysis bahia) 

NOAEC = 101 mg/L 

LOAEC > 101 mg/L 

-- 489392-03 

Aquatic plants 

and algae 

Vascular Duckweed (Lemna 

gibba) NOAEC = 44 mg/L -- 462358-26 

Nonvascular 

Green Algae 

(Pseudokirchneriella 

subcapitata formerly 

Selenastrum 

capricornutum) 

NOAEC = 23 mg/L -- 462358-30 

Freshwater Diatom 

(Navicula 

pelliculosa) 

NOAEC = 6 mg/L -- 462358-27 

Marine Diatom 

(Skeletonema 

costatum) 

NOAEC = 13 mg/L -- 462358-28 

*freshwater fish represent surrogates for aquatic-phase amphibians. 
Page 16 of 63 

b. Effects to Terrestrial Organisms 

Table 8. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for Technical 

Aminopyralid 

Taxonomic 

Group Study Type Surrogate Species

Toxicity Value (all 

units in terms of 

measured acid 

equivalents)

Acute Toxicity 

Classification Source

Birds1

Acute Bobwhite quail 

(Colinus virginianus) 

LD50 > 2250 

mg/kg-bw 

Practically nontoxic 462358-08 

Sub-acute dietary 

Bobwhite quail 

(Colinus virginianus) 

LC50 > 5556 

mg/kg diet 

Practically nontoxic 462358-10 

Mallard Duck (Anas 

platyrhynchos) 

LC50 > 5496 mg/kg 

diet 

Practically nontoxic 462358-11 

Chronic 

Bobwhite quail 

(Colinus virginianus) 

NOAEC = 2500 

mg/ kg diet 

LOAEC > 2500 

mg/kg diet 

-- 471099-01 

Mallard Duck (Anas 

platyrhynchos) 

NOAEC = 2623 

mg/ kg diet 

LOAEC > 2623 

mg/kg diet 

-- 462358-13 

Mammals 

Acute Oral Fischer rat 

(Rattus rattus) 

LD50 > 5000 

mg/kg-bw 

Practically nontoxic 462356-03 

Acute Inhalation Fischer rat 

(Rattus rattus) LD50 > 5.5 mg/L Practically nontoxic 462356-07 

Chronic CD rat (Rattus 

norvegicus) 

NOAEL = 1000 

mg/kg-bw 

LOAEL > 1000 

mg/kg-bw 

-- 462356-35 

Insects Acute Honey bee 

(Apis mellifera L.) 

LD50 = 14.5 μg/bee 

(contact)

Practically nontoxic 462358-31 

LD50 = 14.5 μg/bee 

(oral)

Practically nontoxic 462358-32 

Terrestrial 

plants 

Seedling 

Emergence 

Soybean (Glycine 

max) 

NOAEC = 0.0008 

lbs/A 

EC50 = 0.002 lb/A 

-- 462358-24 

Onion 

(Allium cepa) 

NOAEC = 0.0111 

lbs/A 

EC50 = 0.026 lb/A 

-- 462358-24 

Vegetative Vigor 

Soybean (Glycine 

max) 

NOAEC = 0.0004 

lbs/A 

EC50 = 0.0007 

lbs/A 

-- 462358-25 

Onion 

(Allium cepa) 

NOAEC = 0.043 

lbs/A 

EC50 = 0.07 lbs/A 

-- 462358-25 

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 
Page 17 of 63 

c. Ecological Incidents 

A review on November 19, 2013 of the Ecological Incident Information System (EIIS, version 2.1.1), 

which is maintained by the Agency’s Office of Pesticide Programs, indicates a total of 39 reported 

ecological incidents in the United States associated with the use of the aminopyralid acid and salt active 

ingredients (Appendix E). All 39 of the reported incidents associated with aminopyralid involved damage 

to terrestrial plants and appear to be crop damage. Three of the reported incidents have occurred since the 

time of the most recently completed assessment (USEPA, 2010a, D383620) and these were associated with 

applications to pasture, rights-of-way, and soybeans. The certainty categories12 regarding the likelihood 

that the use of aminopyralid caused the 39 incidents ranged from unlikely (1 incident, 3%), possible (31 

incidents, 86%), and probable (6 incidents, 15%). A summary of incident data is contained in Appendix 

E. 

A large proportion of reported incidences indicate damage to a variety of crops from the use of compost 

(13 incidents, 33%). Other causes included direct application (4 incidents), spray drift/runoff (7 incidents), 

or were not reported (9 incidents). Compost may be a cause of ecological incidents due to the potential 

persistence and toxicity of aminopyralid to terrestrial plants. For example, composted manure containing 

aminopyralid residues was used in gardens in February, 2009 and was incorporated on the date of planting 

in May, 2009. Two different incidents in NC were each connected with the same load of composted 

manure (I021 002-005 and I02076 1-001). One incident involved a commercial organic vegetable farm in 

NC, while the other was a residential organic gardener. The chain of events was similar for both of the 

incidents, i.e., aminopyralid was used on hay, hay was sold to a horse stable, and subsequently horse 

manure was used by organic tomato growers. 

A similar incident, not yet in the EPA EIIS database, is reported in the Bitterroot Valley of Montana 

(Graves, 2009; Sakariassen, 2009). Aminopyralid-contaminated manure was inadvertently applied to 

gardens, resulting in damage to potatoes and other vegetable crops. Tomato and potato damage was 

reported to the Montana Extension services in 2009. Cow manure samples used as the source of compost 

tested positive for the presence of aminopyralid and damage to plants was consistent with that observed 

due to exposure to plant growth regulators. More recently, the use of Green Mountain Valley compost 

contaminated with aminopyralid damaged tomato and other broadleaf garden plants. The source of the 

aminopyralid was manure from horses that had inadvertently consumed aminopyralid residues in feed. 

The contamination led the technical registrant (Dow AgroSciences) to voluntarily change its labeling of 

the chemical, off-labeling its use on pastures in New England or for any purpose in New York. An 

additional incident in Kentucky (1017958-011) reports that six acres of tobacco were adversely affected by 

spray drift at a distance of 200 yards from a labeled use of a formulated product containing aminopyralid 

and 2,4 D. 

 

12 The Ecological Incident Information System (EIIS) used by EPA to store incident data relies on the following certainty indices: 

• Highly Probable: (residues detected in affected organisms and other lines of evidence support cause) 

• Probable: (residues were not measured or the measured residues were not sufficient to be considered toxic, but pesticide 

was used in close proximity and would be capable of exerting such an effect) 

• Possible: multiple pesticides were used in close proximity and any of them are capable of causing such an effect. 

• Unlikely: there are no measured residues and the observed effects are not consistent with those caused by pesticides 

used in the area or there was no pesticide use known in the area. 

• Unrelated: effects observed in the incident are unrelated to pesticide use. 
Page 18 of 63 

7. Exposure Pathways of Concern 

The environmental fate properties and use patterns of aminopyralid indicate that direct spray, spray drift, 

leaching through soil (to groundwater or to surface water via subsurface lateral flow), and runoff represent 

potential transport mechanisms of aminopyralid for exposure to non-target aquatic and terrestrial 

organisms. Drinking water and inhalation exposure pathways were screened using the SIP (Screening 

Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening models. STIR indicated the 

inhalation pathway was of low concern (no LOC exceedances are expected) for birds and mammals. 

Although aminopyralid is practically non-toxic to birds and mammals on an acute exposure basis and 

chronic exposure resulted in no-observed adverse effect levels of >1000 mg/kg diet, the SIP model 

indicated exposure through drinking water alone was of potential concern for acute and chronic risk to

birds and mammals. The avian and mammalian exposure estimates were near or at limit doses tested for 

these taxa; therefore, the high solubility of aminopyralid is driving these concerns (Appendix B ) and the 

extent to which they are of ecological relevance is uncertain. SIP and STIR are described in detail at 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm. 

Analysis of the incident data also supports the possibility that compost, whether through application of 

composted plant materials containing aminopyralid residues or composted manure from horses or cows fed

plant material containing aminopyralid residues, may also be a viable exposure pathway and could result in 

potential injury to non-target plants. Aminopyralid has many incidents in which the chemical was applied 

to pasture/hay which was eaten by ruminants. The chemical was excreted in the animals’ manure, and the 

manure was subsequently composted and used as a terrestrial plant amendment, with resultant damage to 

the plants. Finally, as aminopyralid is persistent and mobile, it may move into surface and groundwater. If 

contaminated water were then used for irrigation, the residues could cause damage to terrestrial plants. 

Aminopyralid applied to trees that are subsequently composted could conceivably cause damage to 

terrestrial plants similar to that caused by composted manure. 

8. Analysis Plan 

a. Stressors of Concern 

i. Ecological Risk Assessment 

The stressors of ecological concern for terrestrial organisms are aminopyralid acid and unextracted 

residues given that the nature of the unextracted residues is uncertain. The only two transformation 

products observed in fate studies were oxamic acid and malonomic acid. As discussed earlier, these are 

amino acid derivatives and are not expected to be of concern. EFED will use a total toxic residues (TTR) 

approach for assessing risk to aminopyralid and unextracted residues in water. EFED will also estimate 

exposure for residues of aminopyralid alone, to get a better understanding of the uncertainty in exposure 

due to the unextracted residues. This is consistent with the approach taken in previous assessments 

completed for aminopyralid. 

 

ii. Drinking Water 

Because EFED recently introduced the PRZM-GW model for determining EDWCs in groundwater, an 

updated drinking water assessment will be completed. The HED will likely conduct a new dietary 

exposure and risk assessment if there are significant changes in the EDWCs. EDWCs will be calculated 

for residues of aminopyralid acid plus unextracted residues and for aminopyralid alone. This is consistent 

with the approach taken in previous assessments for aminopyralid.
Page 19 of 63 

b. Measures of Exposure 

EFED will use standard available models (identified in Table 9) to evaluate potential exposures to aquatic 

and terrestrial organisms as described at http://www.epa.gov/pesticides/science/models_db.htm. 

Since the previous exposure assessments were completed, two main changes in standard procedures have 

been made: 

1) The North American Free Trade Agreement (NAFTA) Guidance for Evaluating and Calculating 

Degradation Kinetics in Environmental Media (NAFTA, 2012; USEPA, 2012b) was completed. 

Degradation kinetics may be recalculated consistent with the updated approach. 

2) A new model for estimating concentrations in groundwater was developed called the Pesticide Root 

Zone Model – Groundwater (PRZM-GW) (USEPA, 2013a). This model will be used along with the 

Screening Concentration in Groundwater (SCI-GROW) model to estimate concentrations in 

groundwater. 

The most up-to-date procedures and models will be used in the Registration Review exposure assessments. 

Nonstandard modeling procedures that may be used in the risk assessment are discussed below. In the 

absence of data to the contrary, the T-REX model will rely on a 35-day foliar dissipation rate value. 

Aquatic Assessment for Residential and Rights-of-Way 

EFED is currently exploring methods to assess urban and residential uses on a national basis. At the 

present time, EFED considers the use of the impervious scenario (a PRZM modeling scenario) as the most

suitable available modeling approach for impervious runoff. This procedure was originally developed for 

the assessments completed for endangered species in California.13 The PRZM impervious scenario may be 

used in the tier II coupled aquatic models PRZM/EXAMS along with a residential or other suitable 

scenario such as rights-of-way (ROW) to obtain estimated environmental concentrations (EECs). The 

conceptual model for the residential scenario integrates simultaneous modeling of the individual use 

scenario with an impervious scenario. This approach assumes that no watershed is completely covered by 

either the 1⁄4-acre lot (the basis for the residential scenario) or undeveloped land (the basis for the ROW 

scenario) for residential and ROW use patterns; therefore, differential amounts of runoff will occur within 

the watershed. The impervious scenario was developed to represent the paved areas within a watershed 

not including roads, parking lots, sidewalks, and buildings outside the 1⁄4-acre lot (the 1⁄4-acre lot scenario 

accounts for impervious surfaces such as buildings within the represented area). By modeling a separate 

scenario for impervious surfaces, it is also possible to estimate that amount of exposure that could occur 

when the pesticide is over-sprayed onto this surface. Using two scenarios in tandem requires postprocessing of the modeled output in order to derive a weighted EEC that represents the contribution of

both the pervious (i.e., residential and ROW scenarios) and the impervious surfaces. Exposure from both 

scenarios can also be weighted and aggregated. The daily time series from each model run from the times 

series file (NAME_TS.out) generated from the PRZM graphical user interface (PE5.pl) residential and 

impervious surface scenarios are combined using Microsoft®

 Excel. The time-series data are weighted 

based on percentage of impervious surface, the percentage of the pervious surface treated, and an adjusted 

time series is created. Rolling averages for the relevant durations of exposure (e.g., 21-day and 60-day 

averages) are calculated, and the relevant one-in-ten year return EEC is generated from these distributions. 

Applications Directly to Water 

The Pesticides in Flooded Applications Model (PFAM; http://www.epa.gov/oppefed1/models/water/), 

which models applications to flooded areas (e.g., rice paddies), will be used to estimate aquatic EECs for 

 

13 http://www.epa.gov/espp/litstatus/effects/redleg-frog/ 
Page 20 of 63 

direct applications to water. Information from aquatic dissipation studies will be used to supplement

modeled EECs. 

Irrigation Water 

EFED does not currently have a standardized methodology for determining risk to non-target plants from

applications of irrigation water where surface or groundwater has been contaminated by a pesticide applied 

to crops. However, EFED anticipates that an irrigation water analysis will be conducted at the time of the 

risk assessment using exposure values generated from currently available models such as PRZM/EXAMS 

for surface water or PRZM-GW for groundwater exposures. This approach will be used to determine a 

depth (in inches) of irrigation water on a one-acre field necessary to cause an LOC exceedance to 

terrestrial plants and compared with representative cultural practices to characterize the potential risk 

associated with this exposure scenario. 

Compost 

Analysis of the incident data also supports the possibility that compost, whether through application of 

composted plant materials containing aminopyralid residues or manure from horses or cows fed such plant 

material, may also be a viable exposure pathway and could result in potential injury to non-target plants 

because of the compound’s persistence. A proposed methodology for evaluating the effects of composted

plant material with aminopyralid residues on non-target terrestrial plants is not currently available, but will 

be investigated at the time of the risk assessment. Methods for analyzing residue levels in compost are 

also needed. 

Applications Directly to Trees 

Applications to individual trees can result in absorption and translocation of aminopyralid from the site of 

application throughout the tree. Birds, mammals, and terrestrial invertebrates may be exposed through

ingestion of leaves, seeds, pollen, or other edible portions of the tree. Leaves containing aminopyralid may 

fall onto the ground or into water resulting in movement of aminopyralid to soil and water. Finally, trees 

treated with aminopyralid may be used as compost. There is no currently approved model for estimating

potential exposure to organisms from tree injection, cut-stump treatment, hack and squirt method, and frill 

and girdle methods. A screening-level estimate of exposure will be completed for this assessment. The 

method used to estimate exposure is discussed in a recently completed assessment in EFED, and the screen 

is based on the following assumptions (USEPA, 2010b, D383620; 2010a, D381025): 

(1) Aquatic Risk Assessment 

a. The total mass of chemical applied to the trees on one acre is assumed to enter a 

20,000,000 L water body directly; EEC = total mass of chemical applied to trees on one 

acre/ 20,000,000 L. 

b. EEC = those estimated in GENEEC for broadcast uses at an assumed maximum 

application rate 

(2) Concentration of chemical in leaves 

a. Leaf concentration may be estimated by assuming that 100% of the chemical is 

translocated to the leaves. Leaf mass may be estimated using allometric equations 

developed for blue oak trees presented by the USDA Forest Service (Karlick and McKay, 

2002). EEC = total mass of chemical applied / leaf mass on tree. 

This exposure estimate approach is not a standard approach, thus assumptions and methods are expected to 

be further developed and refined when the risk assessment is completed. 
Page 21 of 63 

Drinking Water for Ecological Organisms 

Screening-level calculations using SIP have suggested that drinking water exposure may be significant for 

terrestrial organisms. This exposure pathway may be further considered at the time of the risk assessment 

(Appendix B). 

Table 9. List of the various models and the related taxa for which the models will be used. 

Environment Taxa of 

Concern 

Exposure 

Pathway 

Model(s) or 

Pathway Link 

Aquatic 

Fish/ 

Invertebrates

/ Plants 

Runoff and spray 

drift to water PRZM, EXAMS http://www.epa.gov/oppefed1/models/water/

Direct application 

to water PFAM http://www.epa.gov/oppefed1/models/water/

Terrestrial 

Vertebrate Residues in/on 

dietary items T-REX (dietary item) 

http://www.epa.gov/oppefed1/models/

terrestrial/trex/trex_v1_5_webversion.

xlsm

Plant 

Runoff and spray 

drift to plants TerrPlant (Run-off) http://www.epa.gov/oppefed1/models/terrestrial/index.htm#terrplant

Residues in 

irrigation water 

Results from Aquatic 

Models 

http://www.epa.gov/oppefed1/models/

water/

Residues in 

compost To be determined 

Human 

Health 

EDWC 

Vertebrate 

Surface Water PRZM, EXAMS 

http://www.epa.gov/oppefed1/models/

Groundwater water/ SCIGROW 

PRZM-GW 

All 

Environments All Spray Drift 

AgDRIFT (Spray 

drift) 

http://www.agdrift.com/AgDRIFt2/Do

wnloadAgDrift2_0.htm

AGDISP (Spray 

drift) 

http://www.continuumdynamics.com/pr-agdisp.html

 

i. Available Monitoring Data 

The Agency is aware of pesticide monitoring conducted by federal and state agencies. This information

will be considered in the assessment, to the extent that data on aminopyralid are available. 

c. Measures of Effect 

The most sensitive toxicity data presented in Section 6 of this problem formulation will be used to 

calculate risk quotients for the respective taxa. Any additional information submitted by the registrant or 

found in the open literature prior to conduct of the risk assessment will also be considered. The open 

literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2009a), 

which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial 

plants, and wildlife. The evaluation of both sources of data that meet the Agency’s standard for inclusion 

in risk assessments can also provide insight into the direct and indirect effects of pesticides on biotic 

communities from loss of species that are sensitive to the chemicals, and from changes in structure and 

functional characteristics of the affected communities. 

9. Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will 
Page 22 of 63 

evaluate risks to listed species from registered uses of pesticides in Registration Review. The process for 

evaluating potential risks to listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm. 

10. Endocrine Disruptor Screening Program 

Under Federal Food Drug and Cosmetic Act (FFDCA) section 408(p), the Agency must screen all 

pesticide chemicals for potential endocrine disruptor activity. Between October 2009 and February 2010, 

EPA issued test orders/data call-ins for the first group of 67 chemicals, which comprises 58 pesticide

active ingredients and 9 inert ingredients. The herbicide aminopyralid is not among the group of 58 

pesticide active ingredients on the initial list to be screened under the EDSP. For further information on 

the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines 

and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/. 

11. Preliminary Identification of Data Gaps 

a. Environmental Fate

Table 10 identifies environmental fate studies by MRID that offer data for each guideline requirement, as 

well as study classifications and whether or not further data are needed in order to support risk assessment. 

Table 10. Submitted Environmental Fate Data and Study Classifications for Aminopyralid 

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Justification and Assumptions 

EPA will Make in Absence of 

Data 

835.2120 Hydrolysis 46235726 Acceptable No -- 

835.2240 Aqueous photolysis 46235727 Supplemental No 

Not all degradation products over 

10%AR were individually 

identified and quantified in all 

sampling intervals. Available data 

are adequate for the risk assessment 

and to calculate an aqueous 

photolysis rate for aminopyralid. 

835.2410 Soil photolysis 46235728 Supplemental No 

Supplemental due to loss in 

material balance of the irradiated 

samples and variability in material 

balance in dark samples. Available 

data are adequate to calculate a soil 

photolysis rate. 

835.2370 Photodegradation 

in Air No Data -- No -- 
Page 23 of 63 

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Justification and Assumptions 

EPA will Make in Absence of 

Data 

835.4100 Aerobic soil 

metabolism 

46235729 Supplemental 

Not at this time.

There is uncertainty in the identity 

of the unextracted residues. 

Because there was no risk to aquatic 

taxa or for human health drinking 

water in previous assessments when 

unextracted residues were assumed 

to be parent, data to reduce this 

uncertainty are not required. 

Additionally, the most recently 

completed risk assessment indicated 

that assuming that the un-extracted 

residues were parent had little 

impact on EECs. 

47911201 Supplemental 

47925801 Acceptable 

835.4200 Anaerobic soil 

metabolism No data. -- No 

835.4300 Aerobic aquatic 

metabolism 46235731 Supplemental 

Yes (in support 

of current and 

proposed uses) 

Test systems were moderately to 

strongly reducing throughout most 

of the study. In the absence of 

additional data, a value of 2x the 

aerobic soil metabolism input value 

will be used as the model input. 

Having additional data will reduce 

uncertainty in the potential for risk 

to terrestrial plants from residues in 

irrigation water for terrestrial uses. 

For applications directly to water, 

this study will reduce the 

uncertainty for the risk assessment 

for aquatic and terrestrial plants. 

835.4400 Anaerobic aquatic 

metabolism 46235730 Acceptable No -- 

835.1230 

835.1240 

Adsorption/ 

desorption and 

leaching 

46235732 Supplemental No 

Data are available on 8 soils. 

Typically, data are available on 4 

soils and 1 sediment. However, 

data are not available with a test 

soil system <1% organic matter 

content. Available sorption 

coefficients will be used in the risk 

assessments. There will be some 

uncertainty on whether sorption 

coefficients in sediment may be 

different than those found in soils. 

835.1410 Volatility – 

laboratory No data. -- No 

Not expected to be volatile under 

normal use conditions based on low 

vapor pressure and Henry’s Law 

Constant. 

835.6100 Terrestrial field 

dissipation 

46235734 Supplemental 

No -- 

46235735 Under Review 

835.6200 Aquatic field 

dissipation 48939201 Supplemental No 

Storage stability study not available 

for water. Field spike data are 

available and some samples had 

low recoveries (60-70%).. 
Page 24 of 63 

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Justification and Assumptions 

EPA will Make in Absence of 

Data 

48939202 Supplemental 

Application rate lower than that 

proposed. A storage stability study 

was not available for water. 

850.6100 

Analytical method 

for soil or 

sediment* 

47572602 Acceptable 

No 

Submitted studies will likely be 

adequate to serve as the analytical 

method for soil. The LOQ of 0.001 

μg/g-soil (1.0 μg/kg-soil) is 

sufficient to cover the lowest 

measured terrestrial plant endpoint 

of 0.0004 lbs a.i./A (2 μg/kg-soil) 

assuming a 1.5 g/mL soil density 

and six-inch soil depth (MRID 

46235824). 

46235602 

(ECM4) 

46235715 

(ILV3

) 

Acceptable 

Analytical method 

for water* 

46235601 

(ECM4

46235713 

(ILV) 

Acceptable 

No 

Submitted studies will likely be 

adequate to serve as the analytical 

method for water. The lowest 

aquatic endpoint is 6 mg/L for a 

diatom (MRID 46235827). The 

limit of quantitation (LOQ) of 0.05 

μg/L is low enough to cover the risk 

concern in water.

47572602 Acceptable 

Analytical method 

for compost Not submitted -- Yes 

An ECM4 and ILV3 are needed to 

facilitate monitoring of residues of 

aminopyralid in compost. The 

incidents from the use of 

contaminated compost support the 

need for this ECM4

. 

850.1730 Fish 

bioconcentration 

None 

submitted -- No Based on a Kow <-1.76 

Non-guideline Compost 

Dissipation Study 

None 

submitted -- Yes 

Data are needed to understand the 

potential risk to terrestrial plants 

from residues in compost. Data are 

needed to understand degradation in 

compost. A protocol should be 

submitted prior to initiation of the 

study. 
Page 25 of 63 

OCSPP 

Guideline Data Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct risk 

assessment? 

Justification and Assumptions 

EPA will Make in Absence of 

Data 

835.7100 

Prospective 

Groundwater 

Monitoring Study 

None 

submitted -- Yes 

Additional data are recommended 

to better understand the potential 

for risk due to residues of 

aminopyralid in groundwater. 

Studies that would be useful include 

a prospective groundwater 

monitoring study or studies to 

refine groundwater modeling inputs 

for the PRZM-GW model. A 

prospective groundwater 

monitoring study could be used to 

determine where groundwater 

concerns were likely to occur and 

whether what we predict based on 

laboratory data, is observed in the 

field. Additionally, it could be used 

to determine vulnerability of 

different areas. Data to refine 

inputs to PRZM-GW may be used 

to refine modeling estimates of 

groundwater concentrations. 

Studies may involve understanding 

sorption or degradation in 

subsurface environments. It is 

recommended that a protocol be 

submitted, prior to conducting any 

of these studies. In the absence of 

more suitable inputs or scenarios, 

EECs generated from PRZM-GW 

in the same fashion as EDWCs for 

groundwater used as drinking 

water, will be used to characterize 

risks to terrestrial plants from 

residues in irrigation water obtained 

from groundwater sources. 

* The Agency has received studies and/or waiver requests that are currently under review. 

1

 Target limit of quantitation (LOQ) for irrigation water in mg/L= Toxicity Endpoint for terrestrial plant lb a.i./Acre × 

(453,592 mg/lb) × (Acre-in/102,790 L water). The lowest terrestrial plant toxicity endpoint reported is a No 

Observed Adverse Effect Concentration of 0.0004 lb a.i./A for soybean (Glycine max) (MRID 462358-25). 

2

 The two submitted methods on water are essentially the same except for the mobile phase. Therefore, the ILV 

submitted will cover both methods. 

3

 ILV=independent laboratory validation 

4

 ECM=environmental chemistry method 

b. Effects 

Table 11 and 12 identify ecological effect studies by MRID that offer data for each guideline requirement, 

as well as study classifications and whether or not further data are needed in order to support risk 

assessment. The database for the aminopyralid TGAI is relatively complete. However, a number of 

Typical End-Use Products (TEP) are required for risk assessment because i) direct application to open 

water can be expected based on broadly-categorized use sites captured by the product labels and the 
Page 26 of 63 

recently proposed aquatic use (as described in Section 3); and ii) some of the TEPs contain active 

ingredients with similar mode-of-actions compared to aminopyralid and the combinations may result in 

unexpected interactions. 

o The 40 CFR Part 158 (40 CFR 2012) identifies data requirements for conventional pesticides, 

including those pesticides applied directly to water and/or those known to be phytotoxicants 

such as aminopyralid. Of the studies required to support the aquatic use of aminopyralid that 

is currently under review, the following studies are not available in the existing database and 

are therefore necessary for conducting an ecological risk assessment. The studies following 

studies should be conducted using representative products that contain i) aminopyralid and 

2,4-D; ii) aminopyralid and triclopyr; iii) aminopyralid and clopyralid; iv) aminopyralid and 

metsulfuron; and v) aminopyralid and fluroxypyr-1-methylheptyl ester.

• Freshwater invertebrate acute toxicity (OCSPP Guideline 850.1010) 

• Tier II terrestrial plant vegetative vigor (OCSPP Guideline 850.4150) and seedling 

emergence (OCSPP 850.4250). The studies should include the most sensitive species 

(Dicot: soybean, lettuce; Monocots: onion), as indicated in currently available data. 

• Aquatic plant growth (freshwater diatom, Navicula pelliculosa) (Tier II) (OCSPP 

Guideline 850.4500) 

o Additional study requirements based upon the current and proposed use patterns include: 

• cyanobacteria toxicity study (OCSPP 850.4550) using a TEP that contains 

aminopyralid only due to the potential for direct application to open water sources. 

Although terrestrial plants appear to be the most sensitive taxa to aminopyralid 

toxicity, the lack of an acceptable study on cyanobacteria is an uncertainty. 

• Non-standard study (OECD 237) to assess TGAI aminopyralid toxicity to developing 

bee larva. 

Based on the weight of evidence (i.e., that uses of aminopyralid did not previously result in acute risk 

concerns for terrestrial and aquatic vertebrates or invertebrates, and that nonvascular plants are not the 

most sensitive aquatic plant species for aminopyralid), the previously listed studies will likely be sufficient 

to evaluate the potential for risk for the proposed use patterns. If the studies indicate the formulated 

products are more toxic compared to the TGAI, then it will be assumed that the toxicity to other taxa will 

be increased as well. 

Furthermore, the mysid life cycle with TGAI (OCSPP 850.1350) and the avian acute oral toxicity for a 

passerine using TGAI (OCSPP 850.2100) have previously been triggered based on other aminopyralid 

uses but previous risk assessments have indicated they are not required to preclude risk. It is likely that the 

same conclusion will be reached for current and proposed use under review. 

available chronic studies on invertebrates and preliminary estimates of exposure suggest direct risk 

to the TGAI alone at current expected exposure levels will be low. When the risk assessment is 

completed, it may be possible to preclude direct risk to these species based on available data; and. 

an acute oral toxicity study with a passerine species was a data gap identified in a previous risk 

assessment (USEPA, 2010a). Data for passerine species are required under the new 40 CFR Part 

158 (Oct. 26, 2007). Part 158 data requirements specify that avian acute oral toxicity data (OCSPP 

Guideline 850.2100) be submitted for either a mallard duck or bobwhite quail and a passerine 

species. However, there were no mortalities in acceptable acute studies in the bobwhite quail or 

subchronic dietary studies in the bobwhite quail and mallard duck. Furthermore, there have been 

no incidents involving avian species according to the Avian Incident Monitoring System (AIMS). 

The previous risk assessments have not identified any risk to avian species and we do not expect 
Page 27 of 63 

this risk conclusion to change for the proposed use. Therefore, we are not requesting these data at 

this time. 

Table 11. Submitted Aquatic Ecological Effects Data and Study Classifications for Aminopyralid. 

OCSPP 

Guideline 

Data 

Requirement 

Study 

Type 

Submitted 

Studies 

(MRID) 

Study Classification

Are data 

needed to 

conduct risk 

assessment

Justification and 

Assumptions EPA will Make 

in Absence of Data - Some 

Example texts are include

850.1010 

Freshwater 

invertebrate 

toxicity 

Acute 

46235817 Acceptable 

No --

48939301 Under Review 

48939401 Under Review 

48939501 Under Review 

850.1025 

850.1035 

850.1045 

850.1055 

Saltwater 

invertebrate 

toxicity 

Acute 

46235818 Acceptable 

No -- 

48939302 Under Review 

48939502 Under Review 

46235819 Acceptable 

48939303 Under Review 

48939503 Under Review 

 850.1075 Freshwater fish Acute 

46235814 Acceptable 

No -- 

46235815 Supplemental 

46235816 Supplemental 

48939304 Under Review 

48939402 Under Review 

48939504 Under Review 

 850.1075 Saltwater fish Acute 

46235820 Acceptable 

No -- 

48939305 Under Review 

850.1300 

Freshwater 

invertebrates life 

cycle 

Chronic 

46235822 Acceptable 

No -- 

46235823 Supplemental 

 850.1350 

Saltwater 

invertebrates 

life cycle 

Chronic 48939203 Acceptable No -- 

 850.1400 Freshwater fish 

early-life stage Chronic 46235821 Supplemental No -- 

 850.1400 Saltwater fish 

early-life stage Chronic 48939204 Acceptable No -- 

 850.1500 Freshwater fish 

full life cycle Chronic (None) (N/A) No -- 

850.1735 

850.1740 

10-day Sediment 

Toxicity Test Subacute (None) (NA) No 

850.4400 

Aquatic plant 

Toxicity Test 

using Lemna 

minor. 

-- 46235826 Acceptable No --

850.5400 Algal toxicity 

 46235827 Supplemental 

 48939403 Under Review No -- 

 46235828 Acceptable 
Page 28 of 63 

 47109902 Supplemental 

850.4550 Cyanobacteria 46235829 Unacceptable Yes 

Due to the lack of an 

acceptable study, EFED is 

requesting a study using the 

TGAIo-- 

Table 12. Submitted Terrestrial Ecological Effects Data for Aminopyralid. 

OCSPP 

Guideline 

Data 

Requirement Study Type 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

needed for 

risk 

assessment 

Current Additional Data 

Need 

850.2100 

Avian oral 

toxicity Acute 

46235808 Acceptable 

No --

46235809 Supplemental 

Passerine Acute (None) (NA) No

Acute avian oral toxicity data 

are required for either one 

waterfowl or one upland game 

species and one passerine 

species under the 40 CFR Part 

158 (2010) data requirements 

for conventional pesticides 

with outdoor uses . However, 

there were no mortalities in 

acute or subchronic dietary 

studies including bobwhite 

quail and mallard duck and it 

is likely that results of a 

passerine species will be 

similar. Therefore, this study 

is not being required. 

850.2200 Avian dietary 

toxicity Subacute 

46235810 Acceptable 

No -- 

46235811 Acceptable 

850.2300 Avian 

reproduction Chronic 

46235812 Supplemental 

46235813 Acceptable No -- 

47109901 Acceptable 

Nonguideline Avian inhalation Acute (None) (NA) No 

Aminopyralid has a vapor 

point of 1.94 x10-10 Torr and is 

not expected to volatilize. 

EFED’s STIR model further 

indicated that inhalation is not 

likely to be a significant 

pathway for exposure. 

Therefore, this study is not 

required at this time.

850.3020 Honey bee acute 

contact toxicity Acute 46235831 Acceptable No -- 
Page 29 of 63 

OCSPP 

Guideline 

Data 

Requirement Study Type 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

needed for 

risk 

assessment 

Current Additional Data 

Need 

46235832 Supplemental 

Honey bee larval 

toxicity test 

(OECD 237) 

Acute (None) (NA) Yes 

This study is being required to 

assess the toxicity of 

aminopyralid to developing 

bee larva 

850.3030 

Honey bee 

residue on 

foliage 

-- (None) (NA) No 

The LD50 for the honey bee 

acute contact study was 14.5 

μg a.i./bee, above the trigger 

for the honey bee residue on 

foliage study of 11 μg/bee. 

Furthermore, aminopyralid has 

not been highlighted as a 

pervasive pesticide in bee 

colonies and oral exposure 

will be negligible based on the 

use pattern. Therefore, this 

study is not being required at 

this time. 

850.3040 Field testing for 

pollinators -- (None) (NA) No See explanation for Honey bee residue on foliage.

850.4100 

Seedling 

Emergence and 

Seedling Growth

-- 46235824 Supplemental Yes 

New tier data using 

representative TEPs are 

required for the most sensitive 

species (i.e., soybean, lettuce, 

and onion) 850.4250 Vegetative 

Vigor -- 46235825 Supplemental Yes 

* The Agency has received studies and/or waiver requests that are currently under review. 

Table 13. Summary of Additional Data Requirements for Representative Typical End-Use Products 

Containing Multiple Active Ingredients. 

OCSPP 

Guideline Data Requirement 

Nonstandard 

(OECD 237) 

Honey bee larval toxicity test This study using TGAI is required to assess aminopyralid 

toxicity to developing bee larva 

850.1010 Freshwater invertebrate acute toxicity* 

Data are needed on a representative products that contain i) 

aminopyralid and 2,4-D; ii) aminopyralid and triclopyr; iii) 

aminopyralid and clopyralid; iv) aminopyralid and metsulfuron; 

and v) aminopyralid and fluroxypyr-1-methylheptyl ester.

850.4150 Terrestrial plant vegetative vigor (soybean, lettuce, 

onion)* 

850. Seedling Emergence (soybean, lettuce, onion) 

850.4500 Aquatic plant growth (freshwater diatom, Navicula 

pelliculosa) (Tier II)* 

850.4550 Aquatic plant growth for cyanobacteria* TEP containing aminopyralid only 

8501075 Freshwater fish acute toxicity Several studies with representative TEPs are triggered by 

proposed aquatic use pattern. However, since the represented 

taxa do not represent the most sensitive species and did not result 

in risks of concern in prior assessments, the studies listed above 

will likely be sufficient to evaluate potential risk for the proposed 

use patterns. 

850.4400 Aquatic plant toxicity using Lemna sp. 

850.1035 Acute toxicity mysid 

850.1075 Acute toxicity estuarine/marine fish 

850.1025 Acute toxicity estuarine/marine mollusc 
Page 30 of 63 

850.1350 Mysid life cycle with TGAI Previous risk assessments listed these studies as data gaps, 

however, they are not required to preclude risk. 850.2100 Avian acute oral toxicity for passerine with TGAI 

* The Agency has received studies and/or waiver requests that are currently under review 

12. References 

Armitage, J. M., & Gobas, F. A. P. C. 2007. A terrestrial food-chain bioaccumulation model for POPs. 

Environmental Science and Technology, 41, 4019-4025. 

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Division Editorial Group (Ed.), Pesticide Disposal Series 8. Assessing Soil Contamination. A 

Reference Manual. Rome: Food & Agriculture Organization of the United Nations (FAO). 

Available at http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm (Accessed July 10, 2009). 

Graves, M. 2009. Residual Herbicide Can Damage Sensitive Garden Plants. Montana Pesticide Bulletin, 

December 2009. 

HRAC. 2005. Classification of Herbicides According to Mode of Action, Herbicide Resistance Action 

Committee (HRAC): Herbicide Resistance Action. Available at 

http://www.hracglobal.com/Publications/ClassificationofHerbicideModeofAction/tabid/222/Defau

lt.aspx (Accessed October 23, 2013). 

Karlick, J. F., & McKay, A. H. 2002. Leaf Area Index, Leaf Mass Density, and Allometric Relationships 

Derived From Harvest of Blue Oaks in a California Oak Savanna. General Technical Report 

PSW-GTR-184. USDA Forest Service. 

NAFTA. 2012. Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media. 

December 2012. NAFTA Technical Working Group on Pesticides. Available at 

http://www.epa.gov/oppfead1/international/naftatwg/guidance/degradation-kin.pdf (Accessed 

December 16, 2013). 

Sakariassen, A. 2009. Sullied soil: Missoula Independent Free Thinking. Blog. Available at 

http://missoulanews.bigskypress.com/IndyBlog/archives/2009/08/25/sullied-soil (Accessed 

USEPA. 2004.D306647. EFED Reduced Risk Screening Memo for Aminopyralid. D306647. October 19, 

2004. Environmental Fate and Effects Division. Office of Pesticide Programs. 

USEPA. 2005.D301682. Aminopyralid Section 3: Environmental Fate and Effects Risk Assessment. 

D301682, D301691, D301658, D306825. May 10, 2005. Environmental Fate and Effects 

Division, Office of Pesticide Programs. United States Environmental Protection Agency. 

USEPA. 2005. Aminopyralid: Tier I Estimated Drinking Water Concentrations (EDWC) for Use in the 

Human Health Risk Assessment. D301682. February 3, 2005. Environmental Fate and Effects 

Division, Office of Pesticide Programs, United States Environmental Protection Agency. 

USEPA. 2006. Standardized Soil Mobility Classification Guidance. Memorandum From S. Bradbury to E. 

F. a. E. Division. April, 21, 2006. Environmnental Fate and Effects Division. Office of Pesticide 

Programs. Office of Prevention, Pesticides, and Toxic Substances. United State Environmental 

Protection Agency. 

USEPA. 2008. Fate, Transport, and Transformation Guidelines. OPPTS 835.6100 Terrestrial Field 

Dissipation. EPA 712-C-08-020. October 2008. Office of Prevention, Pesticides, and Toxic 

Substances. Available at http://www.epa.gov/opptsfrs/publications/835_6100.pdf (Accessed July 

30, 2009). 

USEPA. 2009.D361924. Ecological Risk Assessment for the Triisopropanolamine Salt of Aminopyralid 

Section 3 New Uses on Field Corn and Field Corn grown for Ensilage. D361924. October 22, 

2009. Environmental Fate and Effects Division. Office of Pesticide Programs. 

USEPA. 2009a. ECOTOXicology Database, United States Environmental Protection Agency (USEPA). 

Available at http://cfpub.epa.gov/ecotox/ (Accessed June 19, 2009). 

USEPA. 2009b. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides, Version 2.1. Available at 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (Accessed November 

12, 2010). 
Page 31 of 63 

USEPA. 2009c. SAP Minutes No. 2009-01. A set of Scientific Issues Being Considered by the 

Environmental Protection Agency Regarding: Selected Issues Associated with the Risk 

Assessment Process for Pesticides with Persistent, Bioaccumulative, and Toxic Characteristics. 

October 28-31, 2008. January 29, 2009. FIFRA Scientific Advisory Panel. Office of Science 

Coordination and Policy. Available at 

http://www.epa.gov/scipoly/sap/meetings/2008/102808_mtg.htm (Accessed July 9, 2009). 

USEPA. 2010a.D383620. Ecological Risk Assessment for the Proposed Section 24C New Use of 

Triisopropanolamine Salt of Aminopyralid for Control of Herbaceous Broadleaf Weeds and 

Woody Plants in Forests, Non-cropland, Grazed areas, and Industrial Non-crop Areas in 

Arkansas. D383620. December 7, 2010. Environmental Fate and Effects Division. Office of 

Pesticide Programs. Office of Chemical Safety and Pollution Prevention. United States 

Environmental Protection Agency. 

USEPA. 2010. Guidance for Reporting on the Environmental Fate and Transport of the Stressors of 

Concern in the Problem Formulation for Registration Review, Registration Review Risk 

Assessments, Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other 

Relevant Risk Assessments. January 25, 2010. Environmental Fate and Effects Division, . 

Available at 

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_re

registration_workgroup/esa_reporting_fate.htm (Accessed July 5, 2012). 

USEPA. 2010a.D381025. Section 3 Product Registration Request for Expansion of Tree Species for 

Emamectin Benzoate Tree Injection Use to Control Arthropod Pests. D381025. October 5, 2010. 

Environmental Fate and Effects Division. Office of Pesticide Programs. Office of Chemical 

Safety and Pollution Prevention. United States Environmental Protection Agency. 

USEPA. 2010b.D383620. Tier I Drinking Water Exposure Assessment for the Section 24C (Special Local 

Need) New Use of Triisopropanolamine Salt of Aminopyralid for Control of 

Herbaceous Broadleaf Weeds and Woody Plants in Forests, Non-cropland,Grazed areas, and Industrial 

Non-crop Areas in Arkansas. D383620. December 6, 2010. Environmental Fate and Effects 

Division. Office of Pesticide Programs. Office of Chemical Safety and Pollution Prevention. 

United States Environmental Protection Agency. 

USEPA. 2012a. Criteria Used by the PBT Profiler. September 4, 2012. Office of Chemical Safety and

Pollution Prevention. United States Environmental Protection Agency. Available at 

http://www.pbtprofiler.net/criteria.asp (Accessed September 7, 2012). 

USEPA. 2012b. Standard Operating Procedure for Using the NAFTA Guidance to Calculate 

Representative Half-life Values and Characterizing Pesticide Degradation. November 30, 2012. 

Environmental Fate and Effects Division. Office of Pesticide Programs. United States 

Environmental Protection Agency. Available at 

http://www.epa.gov/oppefed1/ecorisk_ders/degradation_kinetics/NAFTA_Degradation_Kinetics.h

tm (Accessed December 16, 2013). 

USEPA. 2013.D410811. Aminopyralid Section 3 New Aquatic Use: Screen of Data Package and 

Identification of Data Gaps. D410811. June 3, 2013. Environmental Fate and Effects Division. 

Office of Pesticide Programs. Office of Chemical Safety and Pollution Prevention. United States 

Environmental Protection Agency. 

USEPA. 2013a. Guidance for Using PRZM-GW in Drinking Water Exposure Assessments. December 11, 

2012. Environmental Fate and Effects Division. Office of Pesticide Programs. United States 

Environmental Protection Agency. Available at 

http://www.epa.gov/oppefed1/models/water/przm_gw/wqtt_przm_gw_guidance.htm (Accessed 

January 22, 2013). 

USEPA. 2013b. Screening Level Estimates of Agricultural Uses of Aminopyralid. Biological and 

Economic Analysis Division. Office of Pesticide Programs. Office of Chemical Safety and 

Pollution Prevention. United States Environmental Protection Agency. 

Ware, G. W., & Whitacre, D. M. 2004. An Introduction to Herbicides. In E. B. Radcliffe & W. D. 

Hutchison (Eds.), The Pesticide Book (6th ed.). Willoughby, OH: MeisterPro Information 
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Resources. Available at http://ipmworld.umn.edu/chapters/whitacreherb.htm (Accessed October 

17, 2013). 

Wood, A. 2013. Compendium of Pesticide Common Names. Available at 

http://www.alanwood.net/pesticides/index.html (Accessed October 17, 2013). 
Page 33 of 63 

Appendix A. Bibliography of Submitted Studies 

Environmental Fate 

MRID Citation Reference 

161-1 Hydrolysis 

46235726 Cook, W. (2003) Hydrolysis of XDE-750 at pH 5, 7, and 9. Project Number: 

020067. Unpublished study prepared by Dow AgroSciences LLC. 45 p. 

161-2 Photodegradation-water 

46235727 Cook, W. (2003) Aqueous Photolysis of XDE-750 in pH 5 Buffer Under Xenon 

Light. Project Number: 020066. Unpublished study prepared by Dow AgroSciences 

LLC. 92 p. 

161-3 Photodegradation-soil 

46235728 Rutherford, L. (2004) Photodegradation of XDE-750 on Soil. Project Number: 

020080. Unpublished study prepared by Dow AgroSciences LLC. 80 p. 

162-1 Aerobic soil metabolism 

46235729 Yoder, R.; Smith, K. (2002) Aerobic Soil Degradation of XDE-750 in Five North 

American Soils. Project Number: 010091. Unpublished study prepared by Dow 

AgroSciences LLC. 106 p. 

162-3 Anaerobic aquatic metab. 

46235730 Rutherford, L.; Meitl, T. (2004) Anaerobic Aquatic Metabolism of XDE-750. 

Project Number: 020052. Unpublished study prepared by Dow AgroSciences LLC. 

73 p. 

162-4 Aerobic aquatic metab. 

46235731 Yoder, R.; Smith, K. (2003) Degradation of XDE-750 in 2 European and 1 US 

Sediment and Pond Water Systems. Project Number: 020062. Unpublished study 

prepared by Dow AgroSciences LLC. 88 p. 

163-1 Leach/adsorp/desorption 

46235729 Yoder, R.; Smith, K. (2002) Aerobic Soil Degradation of XDE-750 in Five North 

American Soils. Project Number: 010091. Unpublished study prepared by Dow 

AgroSciences LLC. 106 p. 

46235732 Rutherford, L. (2002) Soil Batch Equilibrium Adsorption/Desorption of XDE-750. 

Project Number: 010064. Unpublished study prepared by Dow AgroSciences LLC. 

128 p. 

164-1 Terrestrial field dissipation 

46235713 Reed, R (2004) Independent Laboratory Validation of Dow AgroSciences Method 

GRM 01.32 - Determination of Residues of Aminopyralid in Water by Liquid 

Chromatography with Tandem Mass Spectrometry. Project Number: 030039, 

ML03/1111/DOW. Unpublished study prepared by Morse Laboratories. 113 p. 

46235715 Reed, R. (2004) Independent Laboratory Validation of Dow AgroSciences Method 

GRM 02.34 - Determination of Residues of Aminopyralid in Soil by Liquid 

Chromatography with Tandem Mass Spectrometry. Project Number: 020158, 

ML03/1102/DOW. Unpublished study prepared by Morse Laboratories. 125 p. 
Page 34 of 63 

MRID Citation Reference 

46235734 Roberts, D. (2004) Terrestrial Field Dissipation of XDE-750 in the USA. Project 

Number: 020032. Unpublished study prepared by Dow AgroSciences LLC. 158 p. 

46235735 Roberts, D.; Schelle, G. (2004) Terrestrial Field Dissipation of XDE-750 in Canada. 

Project Number: 020031, ELECTRONIC/COPY. Unpublished study prepared by 

Dow AgroScience LLC. 302 p. 

830.7050 UV/Visible absorption 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

46235704 Cathie, C. (2003) Group B: Determination of Physical State, Colour, Odor, 

Oxidizing and Reduction Action, Flammability, Explodability, pH, Viscosity and 

Density of GF-871, a Liquid End-Use Product Containing XR-750 TIPA. Project 

Number: 02/070/L. Unpublished study prepared by Dow Agrosciences (New 

Zealand) Ltd. 17 p. 

46235705 McFarlane, J. (2003) Group B-Physical/Chemical Properties for GF-871, A Liquid 

End Use Product Containing XR-750 TIPA. Project Number: NAFST788: 

GHF/P/2709. Unpublished study prepared by Dow Agrosciences, LLC. 5 p. 

46434202 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-982, A Liquid 

End Use Product Containing Aminopyralid and Fluoroxypyr (Revised Report). 

Project Number: NAFST824. Unpublished study prepared by Dow AgroSciences 

LLC. 5 p. 

46434302 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-1004, A Liquid 

End Use Product Containing Aminopropyralid and 2,4-D. Project Number: 

NAFST/04/868. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

46942402 Jones, J. (2006) Group B - Physical/Chemical Properties for GF-1883, A Liquid End 

Use Product Containing Aminopyralid and Triclopyr. Project Number: 

NAFST/06/098. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

47290636 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-1004, A Liquid 

End Use Product Containing Aminopyralid and 2,4-D. Project Number: 

NAFST/04/868. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

830.7300 Density/relative density 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

46235704 Cathie, C. (2003) Group B: Determination of Physical State, Colour, Odor, 

Oxidizing and Reduction Action, Flammability, Explodability, pH, Viscosity and 

Density of GF-871, a Liquid End-Use Product Containing XR-750 TIPA. Project 

Number: 02/070/L. Unpublished study prepared by Dow Agrosciences (New 
Page 35 of 63 

MRID Citation Reference 

Zealand) Ltd. 17 p. 

46235705 McFarlane, J. (2003) Group B-Physical/Chemical Properties for GF-871, A Liquid 

End Use Product Containing XR-750 TIPA. Project Number: NAFST788: 

GHF/P/2709. Unpublished study prepared by Dow Agrosciences, LLC. 5 p. 

46434202 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-982, A Liquid 

End Use Product Containing Aminopyralid and Fluoroxypyr (Revised Report). 

Project Number: NAFST824. Unpublished study prepared by Dow AgroSciences 

LLC. 5 p. 

46434302 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-1004, A Liquid 

End Use Product Containing Aminopropyralid and 2,4-D. Project Number: 

NAFST/04/868. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

46942402 Jones, J. (2006) Group B - Physical/Chemical Properties for GF-1883, A Liquid End 

Use Product Containing Aminopyralid and Triclopyr. Project Number: 

NAFST/06/098. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

47290636 McFarlane, J. (2004) Group B-Physical/Chemical Properties for GF-1004, A Liquid 

End Use Product Containing Aminopyralid and 2,4-D. Project Number: 

NAFST/04/868. Unpublished study prepared by Dow AgroSciences LLC. 5 p. 

830.7370 Dissociation constants in water 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

46235706 Hamilton, T. (2004) Amended Report for Dissociation of XDE-750 

Trilsopropanolamine Salt. Project Number: DECO/GL/AL/MD/2002/004418. 

Unpublished study prepared by The Dow Chemical Company. 21 p. 

46235707 Hamilton, T. (2004) Amended Report for Dissociation of XDE-750 Potassium Salt. 

Project Number: GL/AL/MD/2002/004397. Unpublished study prepared by The 

Dow Chemical, Co. 21 p. 

46235706 Hamilton, T. (2004) Amended Report for Dissociation of XDE-750 

Trilsopropanolamine Salt. Project Number: DECO/GL/AL/MD/2002/004418. 

Unpublished study prepared by The Dow Chemical Company. 21 p. 

46235706 Hamilton, T. (2004) Amended Report for Dissociation of XDE-750 

Trilsopropanolamine Salt. Project Number: DECO/GL/AL/MD/2002/004418. 

Unpublished study prepared by The Dow Chemical Company. 21 p. 

830.7550 Partition coefficient (n-octanol/water), shake flask method 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

830.7840 Water solubility: Column elution method, shake flask method 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

830.7950 Vapor pressure 
Page 36 of 63 

MRID Citation Reference 

46235703 Ghaoui, L. (2003) Group B: Physical and Chemical Properties of Aminopyralid 

(XDE-750) Technical. Project Number: NAFST744, DOS323/024653, 

FAPC/013053. Unpublished study prepared by Dow Agrosciences LLC, Dow 

Agrosciences (New Zealand) Ltd. and The Dow Chemical, Co. 313 p. 

835.1220 Sediment and soil absorption /desorption isotherm 

46235732 Rutherford, L. (2002) Soil Batch Equilibrium Adsorption/Desorption of XDE-750. 

Project Number: 010064. Unpublished study prepared by Dow AgroSciences LLC. 

128 p. 

835.4100 Aerobic soil metabolism 

47925801 Sarff, P. (2009) Degradation of Aminopyralid in Three US Soils Under Aerobic 

Conditions. Project Number: 64104, 080154. Unpublished study prepared by ABC 

Laboratories, Inc. 104 p. 

835.6200 Aquatic field dissipation 

47971401 (2010) Dissipation and Aquatic Organism Residue Monitoring of Aminopyralid in 

Small Ponds: Protocol. Project Number: 101046. Unpublished study prepared by 

Dow AgroSciences, LLC. 12 p. 

47971402 (2010) Dissipation of Aminopyralid in Flowing Water Systems Under Operational 

Conditions: Protocol. Project Number: NA10L1B029. Unpublished study prepared 

by Dow AgroSciences, LLC. 9 p. 

48939201 Moore, D.; Newcombe, A.; Havens, P. (2012) Dissipation of Aminopyralid in 

Flowing Water Systems Under Operational Conditions: Final Report. Project 

Number: 110423. Unpublished study prepared by Agvise Laboratories, Inc., Dow 

AgroSciences LLC, ARCADIS U.S., Inc. and Covance Laboratories, Inc. 369p. 

48939202 Newcombe, A.; Negley, T.; Havens, P. (2012) Dissipation and Aquatic Organism 

Residue Monitoring of Aminopyralid in Small Ponds: Final Report. Project Number: 

101046. Unpublished study prepared by Agvise Laboratories, Inc., ARCADIS U.S., 

Inc. and Dow AgroSciences, LLC. 376p. 

860.1340 Residue analytical method 

46235712 Reed, R. (2004) Independent Laboratory Validation of Dow AgroSciences LLC 

Method GRM 02.31 - Determination of Residues of Aminopyralid in Agricultural 

Commodities by Liquid Chromatography with Tandem Mass Spectrometry 

Detection. Project Number: 020157, ML03/1110/DOW. Unpublished study prepared 

by Morse Laboratories. 147 p. 

46235714 Reed, R. (2004) Independent Laboratory Validation of Dow AgroSciences LLC 

Method GRM 03.18 - Determination of Residues of Aminopyralid in Bovine Tissues 

by Liquid Chromatography with Tandem Mass Spectrometry. Project Number: 

030098, ML03/1122/DOW. Unpublished study prepared by Morse Laboratories. 130 

p. 

46235716 Rutherford, L.; Hastings, M. (2003) Method Validation Report for the Determination 

of Aminopyralid in Bovine Tissues by Liquid Chromatography with Tandem Mass 

Spectrometry Using Dow AgroSciences LLC Method GRM 03.18. Project Number: 

021327, GRM/03/18. Unpublished study prepared by Dow AgroSciences LLC. 53 p. 

46235717 Olberding, E.; Hastings, M. (2004) Validation Report for Method GRM 02.31 - 

Determination of Residues of Aminopyralid in Agricultural Commodities by Liquid 

Chromatography with Tandem Mass Spectrometry Detection. Project Number: 

021310, GRM/02/31. Unpublished study prepared by Dow AgroSciences LLC. 61 p. 
Page 37 of 63 

MRID Citation Reference 

46729001 Oberling, E. (2006) A Confirmatory Technique for the Determination of Residues of 

Aminopyralid in Agricultural Commodities by Liquid Chromatography with 

Tandem Mass Spectrometry Detection. Project Number: GH/C/5830, GRM/02/31. 

Unpublished study prepared by Dow Agrosciences LLC. 25 p. 

46729601 Olberding, E. (2004) Validation Report for Method GRM 02.31 - Determination of 

Residues of Aminopyralid in Agricultural Commodities by Liquid Chromatography 

with Tandem Mass Spectrometry Detection. Project Number: 021310. Unpublished 

study prepared by Dow Agrosciences LLC. 62 p. 

46729602 Rutherford, L. (2003) Method Validation Report for the Determination of 

Aminopyralid in Bovine Tissues by Liquid Chromatography with Tandem Mass 

Spectrometry Using Dow AgroSciences LLC Method GRM 03.18. Project Number: 

021327. Unpublished study prepared by Dow AgroSciences LLC. 54 p. 

46729603 Reed, R. (2004) Independent Laboratory Validation of Dow AgroSciences LLC 

Method GRM 02.3.1 - Determination of Residues of Aminopyralid in Agricultural 

Commodities by Liquid Chromatography with Tandem Mass Spectrometry 

Detection. Project Number: 020157, ML03/1110/DOW. Unpublished study prepared 

by Morse Laboratories. 148 p. 

47572602 Wendelburg, B. (2008) Validation Report for Methods GRM 07.07 - Determination 

of Residues of Aminopyralid in Agricultural Commodities by Liquid 

Chromatography with Tandem Mass Spectrometric Detection, GRM 07.08 - 

Determination of Residues of Aminopyralid in Bovine and Poultry Tissues, Milk, 

and Eggs by Liquid Chromatography with Tandem Mass Spectrometric Detection, 

GRM 07.09 - Determination of Residues of Aminopyralid in Soil by Liquid 

Chromatography with Tandem Mass Spectrometric Detection, and GRM 07.10 - 

Determination of Residues of Aminopyralid in Drinking Water, Ground Water, and 

Surface Water by Liquid Chromatography with Tandem Mass Spectrometric 

Detection. Project Number: 071121. Unpublished study prepared by Dow 

AgroSciences, LLC. 207 p. 

860.1380 Storage stability data 

46235719 Lindsay, D. (2004) Frozen Storage Stability of XDE-750 in Range Land and Pasture 

Grass and Hay and Wheat Straw and Wheat Grain - Interim Report. Project Number: 

030004. Unpublished study prepared by Dow AgroSciences LLC. 50 p. 

46235720 Lindsay, D. (2004) Frozen Storage Stability of XDE-750 in Soil--Interim Report. 

Project Number: 030002. Unpublished study prepared by Dow AgroSciences LLC. 

41 p. 

46661301 Lindsay, D. (2004) Frozen Storage Stability of XDE-750 in Range Land and Pasture 

Grass and Hay and Wheat Straw and Wheat Grain. Project Number: 030004/01. 

Unpublished study prepared by Dow Agrosciences LLC. 59 p. 

860.1400 Water, fish, and irrigated crops 

47971401 (2010) Dissipation and Aquatic Organism Residue Monitoring of Aminopyralid in 

Small Ponds: Protocol. Project Number: 101046. Unpublished study prepared by 

Dow AgroSciences, LLC. 12 p. 

48939201 Moore, D.; Newcombe, A.; Havens, P. (2012) Dissipation of Aminopyralid in 

Flowing Water Systems Under Operational Conditions: Final Report. Project 

Number: 110423. Unpublished study prepared by Agvise Laboratories, Inc., Dow 

AgroSciences LLC, ARCADIS U.S., Inc. and Covance Laboratories, Inc. 369p. 
Page 38 of 63 

MRID Citation Reference 

48939202 Newcombe, A.; Negley, T.; Havens, P. (2012) Dissipation and Aquatic Organism 

Residue Monitoring of Aminopyralid in Small Ponds: Final Report. Project Number: 

101046. Unpublished study prepared by Agvise Laboratories, Inc., ARCADIS U.S., 

Inc. and Dow AgroSciences, LLC. 376p. 

850.7100 Data reporting for environmental chemistry methods 

47572602 Wendelburg, B. (2008) Validation Report for Methods GRM 07.07 - Determination 

of Residues of Aminopyralid in Agricultural Commodities by Liquid 

Chromatography with Tandem Mass Spectrometric Detection, GRM 07.08 - 

Determination of Residues of Aminopyralid in Bovine and Poultry Tissues, Milk, 

and Eggs by Liquid Chromatography with Tandem Mass Spectrometric Detection, 

GRM 07.09 - Determination of Residues of Aminopyralid in Soil by Liquid 

Chromatography with Tandem Mass Spectrometric Detection, and GRM 07.10 - 

Determination of Residues of Aminopyralid in Drinking Water, Ground Water, and 

Surface Water by Liquid Chromatography with Tandem Mass Spectrometric 

Detection. Project Number: 071121. Unpublished study prepared by Dow 

AgroSciences, LLC. 207 p. 

 Non-Guideline Study 

46235600 Dow AgroSciences LLC (2004) Submission of Residue and Toxicity Data in 

Support of the Applications for Registration of Aminopyralid Technical and GF-871 

and the Petition for Tolerance of Aminopyralid on Grass Forage, Grass Hay, Wheat 

Commodities, Milk, Cattle Meat and Meat By-Products. Transmittal of 37 of 108 

Studies. 

46235601 Hastings, M. (2003) Method Validation Report for the Determination of Residues of 

Aminopyralid in Water by Liquid Chromatography with Tandem Mass Spectrometry 

Detection Using Dow AgroSciences Method GRM 01.32. Project Number: 011159. 

Unpublished study prepared by Dow AgroSciences LLC. 48 p. 

46235602 Lindsey, A. (2004) Method Validation Report for the Determination of Residues of 

Aminopyralid in Soil by Liquid Chromatography with Tandem Mass Spectrometry 

Detection Using Dow AgroSciences Method GRM 02.34. Project Number: 021295. 

Unpublished study prepared by Dow Agrosciences LLC. 56 p. 

46235700 Dow AgroSciences LLC (2004) Submission of Product Chemistry, Residue and 

Environmental Fate Data in Support of the Applications for Registration of 

Aminopyralid Technical and GF-871 and the Petition for Tolerance of Aminopyralid 

on Grass Forage, Grass Hay, Wheat Commodities, Milk, Cattle Meat and Meat ByProducts. Transmittal of 35 of 108 Studies. 

46235733 Ward, T.; Boeri, R. (2001) XDE-750: 14 Day Soil Exposure Acute Toxicity to the 

Earthworm, Eisenia foetida. Project Number: 2219/DO, 011049. Unpublished study 

prepared by T.R. Wilbury Laboratories, Inc. 34 p. 

46235800 Dow AgroSciences, LLC (2004) Submission of Toxicity, Fate, Risk, and Exposure 

Data in Support of the Applications for Registration of Aminopyralid Technical and 

GF-871 and the Petition for Tolerance of Aminopyralid on Grass Forage, Grass Hay, 

Wheat Commodities, Milk, Cattle Meat and Meat By-Products. Transmittal of 

Studies 36 of 109 Studies. 

46235834 Havens, P. (2004) Spray Drift Assessment for Terrestrial and Aquatic Non-Target 

Plants from the Use of Aminopyralid in Canada. Project Number: GH/C/5708. 

Unpublished study prepared by Dow AgroSciences LLC. 28 p. 

46235835 Nelson, J.; Jachetta, J.; Halstvedt, M.; et. al. (2004) Public Interest Document for 

Aminopyralid . Project Number: PID/DOW03JN01. Unpublished study prepared by 

ABG, Inc. 144 p. 
Page 39 of 63 

MRID Citation Reference 

46259601 Jachetta, J.; Havens, P.; Dybowski, J. et. al. (2004) Reduced-Risk Pesticide 

Rationale for Aminopyralid Technical.. Project Number: JJ042004. Unpublished 

study prepared by Dow Agrosciences LLC. 523 p. 

46434200 Dow AgroSciences LLC (2004) Submission of Product Chemistry and Toxicity Data 

in Support of the Application for Registration of GF-982. Transmittal of 6 Studies. 

46434300 Dow AgroSciences, LLC (2004) Submission of Product Chemistry and Toxicity 

Data in Support of the Application for Registration of GF-1004. Transmittal of 8 

Studies. 

46438900 Dow AgroSciences LLC (2004) Submission of Product Chemistry and Toxicity Data 

in Support of the Application for Registration of GF-982. Transmittal of 2 Studies. 

46661300 Dow Agrosciences LLC (2005) Submission of Product Chemistry and Residue Data 

in Support of the Registration of Aminopyralid Technical and Milestone. Transmittal 

of 2 Studies. 

46729000 Dow Agroscience LLC (2006) Submission of Residue Data in Support of the 

Registration of Aminopyralid Technical. Transmittal of 1 Study. 

46729600 Dow AgroSciences LLC (2006) Submission of Residue Data in Support of the 

Amended Registration of Aminopyralid Technical. Transmittal of 3 Studies. 

46942400 Dow AgroSciences LLC (2006) Submission of Product Chemistry and Toxicity Data 

in Support of the Application for Registration of GF-1883. Transmittal of 14 Studies.

Ecological Effects 

71-1 Avian Single Dose Oral Toxicity 

46235808 Gallagher, S.; Grimes, J.; Beavers, J. (2001) XDE-750: An Acute Oral Toxicity 

Study with the Northern Bobwhite. Project Number: 379/106, 011046. 

Unpublished study prepared by Wildlife International, Ltd. 33 p. 

46235809 Gallagher, S.; Grimes, J.; Beavers, J. (2003) XDE-750 Technical: An Acute Oral 

Toxicity Study with the Northern Bobwhite. Project Number: 379/130, 031112. 

Unpublished study prepared by Wildlife International, Ltd. 34 p. 

48939304 Machado, M. (2002) GF-871 - Acute Toxicity to Rainbow Trout (Oncorhynchus 

mykiss) Under Static Conditions. Project Number: 021147/OCR, 12550/6238. 

Unpublished study prepared by Springborn Smithers Laboratories. 48p. 

71-2 Avian Dietary Toxicity 

46235810 Gallagher, S.; Beavers, J.; Martin, K. (2001) XDE-750: A Dietary LC50 Study 

with the Northern Bobwhite. Project Number: 379/107, 011047. Unpublished 

study prepared by Wildlife International, Ltd. 51 p. 

46235811 Gallagher, S.; Beavers, J.; Martin, K. (2001) XDE-750: A Dietary LC50 Study 

with the Mallard. Project Number: 379/108, 011048. Unpublished study prepared 

by Wildlife International, Ltd. 50 p. 

71-4 Avian Reproduction 

46235812 Mach, J. (2003) Avian Reproduction Study with XDE-750 in Northern Bobwhite 

(Colinus virginianus): Final Report. Project Number: 011271, 02001. 

Unpublished study prepared by Genesis Laboratories, Inc. 122 p. 
Page 40 of 63 

46235813 Mach, J. (2003) Avian Reproduction Study with XDE-750 in Mallards (Anas 

platyrhynchos): Amended Final Report. Project Number: 011272, 02002. 

Unpublished study prepared by Genesis Laboratories, Inc. 124 p. 

72-1 Acute Toxicity to Freshwater Fish 

46235814 Marino, T.; McClymont, E.; Yaroch, A.; et. al. (2001) XDE-750 Herbicide: An 

Acute Toxicity Study with the Rainbow Trout, Oncorhynchus mykiss Walbaum. 

Project Number: 011078. Unpublished study prepared by The Dow Chemical Co. 

36 p. 

46235815 Machado, M. (2003) XDE-750 - Acute Toxicity to Bluegill Sunfish (Lepomis 

macrochirus) Under Static Conditions. Project Number: 12550/6162, 011225. 

Unpublished study prepared by Springborn Laboratories Inc. 47 p. 

46235816 Henry, K.; McClymont, E.; Yaroch, A.; et. al. (2003) XDE-750: 96-h Acute 

Toxicity to Larval Amphibians Using the Northern Leopard Frog, Rana pipiens, 

as a Biological Model. Project Number: 031030. Unpublished study prepared by 

The Dow Chemical Co. 34 p. 

72-2 Acute Toxicity to Freshwater Invertebrates 

46235817 Marino, T.; Hales, C.; McClymont, E.; et. al. (2001) XDE-750 Herbicide: An 

Acute Toxicity Study with the Daphnid, Daphnia magna Straus. Project Number: 

011079. Unpublished study prepared by The Dow Chemical Co. 35 p. 

48939301 Machado, M. (2002) GF-871 - Acute Toxicity to Daphnids (Daphnia magna) 

Under Static Conditions. Project Number: 021146/OCR, 12550/6237. 

Unpublished study prepared by Springborn Smithers Laboratories. 47p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms 

46235818 Cafarella, M. (2002) XDE-750 - Acute Toxicity to Eastern Oysters (Crassostrea 

virginica) Under Flow-Through Conditions. Project Number: 12550/6189, 

011268. Unpublished study prepared by Springborn Laboratories Inc. 53 p. 

46235819 Machado, M. (2002) XDE-750 - Acute Toxicity to Mysids (Americamysis bahia) 

Under Static Conditions. Project Number: 12550/6190, 011269. Unpublished 

study prepared by Springborn Laboratories Inc. 46 p. 

46235820 Machado, M. (2002) XDE-750 - Acute Toxicity to Sheepshead Minnow 

(Cyprinodon variegatus) Under Static Acute Conditions. Project Number: 

12550/6191, 011270. Unpublished study prepared by Springborn Laboratories 

Inc. 47 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study 

46235822 Henry, K.; Marino, T.; Staley, J.; et. al. (2003) XDE-750: 21-Day Chronic 

Toxicity with the Daphnid, Daphnia magna Straus. Project Number: 021085. 

Unpublished study prepared by The Dow Chemical Co. 51 p. 

82-1 Subchronic Oral Toxicity: 90-Day Study 

46235620 Stebbins, K.; Baker, P. (2000) XR-750: 4-Week Dietary Toxicity Study in Beagle 

Dogs. Project Number: 001030. Unpublished study prepared by The Dow 

Chemical Co. 141 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable Vigor 
Page 41 of 63 

46235824 Aufderheide, J. (2004) Effect of GF-871 on Seedling Emergence and Growth of 

Selected Non-Target Terrestrial Plants (Tier II). Project Number: 48322, 030066. 

Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 89 p. 

46235825 Aufderheide, J. (2004) Effect of GF-871 on Vegetative Vigor of Selected NonTarget Terrestrial Plants (Tier II). Project Number: 48323, 030066. Unpublished 

study prepared by Analytical Bio-Chemistry Labs, Inc. 90 p. 

122-2 Aquatic plant growth 

46235826 Hoberg, J. (2003) XDE-750 - Toxicity to Duckweed, Lemna gibba. Project 

Number: 12550/6160, 011223. Unpublished study prepared by Springborn 

Laboratories Inc. 64 p. 

46235827 Hoberg, J. (2002) XDE-750 - Acute Toxicity to the Freshwater Diatom (Navicula 

pelliculosa). Project Number: 12550/6198, 011278. Unpublished study prepared 

by Springborn Laboratories Inc. 61 p. 

46235828 Hoberg, J. (2002) XDE-750 - Growth Inhibition Test with Marine Diatom 

(Skeletonema costatum). Project Number: 12550/6200, 011280. Unpublished 

study prepared by Springborn Laboratories Inc. 62 p. 

46235829 Hoberg, J. (2002) XDE-750 - Growth Inhibition Test with Freshwater Blue-green 

Alga (Anabaena flos-aquae). Project Number: 12550/6199, 011279. Unpublished 

study prepared by Springborn Laboratories Inc. 57 p. 

48939403 Wemhoner, U. (2006) GF-1883 - Growth Inhibition Test with Freshwater Diatom 

(Navicula pelliculosa). Project Number: 060393/OCR, 1072/010/440. 

Unpublished study prepared by Springborn Smithers Laboratories (Europe). 71p. 

123-1 Seed germination/seedling emergence and vegetative vigor 

46235824 Aufderheide, J. (2004) Effect of GF-871 on Seedling Emergence and Growth of 

Selected Non-Target Terrestrial Plants (Tier II). Project Number: 48322, 030066. 

Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 89 p. 

46235825 Aufderheide, J. (2004) Effect of GF-871 on Vegetative Vigor of Selected NonTarget Terrestrial Plants (Tier II). Project Number: 48323, 030066. Unpublished 

study prepared by Analytical Bio-Chemistry Labs, Inc. 90 p. 

123-2 Aquatic plant growth 

46235826 Hoberg, J. (2003) XDE-750 - Toxicity to Duckweed, Lemna gibba. Project 

Number: 12550/6160, 011223. Unpublished study prepared by Springborn 

Laboratories Inc. 64 p. 

46235827 Hoberg, J. (2002) XDE-750 - Acute Toxicity to the Freshwater Diatom (Navicula 

pelliculosa). Project Number: 12550/6198, 011278. Unpublished study prepared 

by Springborn Laboratories Inc. 61 p. 

46235828 Hoberg, J. (2002) XDE-750 - Growth Inhibition Test with Marine Diatom 

(Skeletonema costatum). Project Number: 12550/6200, 011280. Unpublished 

study prepared by Springborn Laboratories Inc. 62 p. 

46235829 Hoberg, J. (2002) XDE-750 - Growth Inhibition Test with Freshwater Blue-green 

Alga (Anabaena flos-aquae). Project Number: 12550/6199, 011279. Unpublished 

study prepared by Springborn Laboratories Inc. 57 p. 

46235830 Hoberg, J. (2003) XDE-750 -Toxicity to the Freshwater Green Alga, 

Pseudokirchneriella subcapitata. Project Number: 12550/6161, 011222. 

Unpublished study prepared by Springborn Laboratories Inc. 66 p. 
Page 42 of 63 

48939403 Wemhoner, U. (2006) GF-1883 - Growth Inhibition Test with Freshwater Diatom 

(Navicula pelliculosa). Project Number: 060393/OCR, 1072/010/440. 

Unpublished study prepared by Springborn Smithers Laboratories (Europe). 71p. 

141-1 Honey bee acute contact 

46235831 Aufderheide, J. (2001) XDE-750: Acute Contact Toxicity Test with the 

Honeybee, Apis mellifera. Project Number: 46595, 011044. Unpublished study 

prepared by Analytical Bio-Chemistry Labs, Inc. 17 p. 

850.1010 Aquatic invertebrate acute toxicity, test, freshwater daphnids 

48939401 Wemhoner, U. (2006) GF-1883 - Acute Toxicity to Water Fleas (Daphnia 

magna) Under Flow-Through Conditions. Project Number: 060395/OCR, 

1072/010/110. Unpublished study prepared by Springborn Smithers Laboratories 

(Europe). 57p. 

48939501 Rebstock, M. (2011) GF-2633: Acute Toxicity to the Water Flea, Daphnia 

magna, Determined Under Static Test Conditions. Project Number: 110056/OCR, 

66953. Unpublished study prepared by ABC Laboratories, Inc. 49p. 

850.1025 Oyster acute toxicity test (shell deposition) 

46235818 Cafarella, M. (2002) XDE-750 - Acute Toxicity to Eastern Oysters (Crassostrea 

virginica) Under Flow-Through Conditions. Project Number: 12550/6189, 

011268. Unpublished study prepared by Springborn Laboratories Inc. 53 p. 

48939302 Gerke, A. (2012) GF-871: Effect on New Shell Growth of the Eastern Oyster 

(Crassostrea virginica). Project Number: 110062/OCR, 66960. Unpublished 

study prepared by ABC Laboratories, Inc. 58p. 

48939502 Gerke, A. (2011) GF-2633: Effect on New Shell Growth of the Eastern Oyster 

(Crassostrea virginica). Project Number: 110059/OCR, 66957. Unpublished 

study prepared by ABC Laboratories, Inc. 59p. 

850.1035 Mysid acute toxicity test 

46235819 Machado, M. (2002) XDE-750 - Acute Toxicity to Mysids (Americamysis bahia) 

Under Static Conditions. Project Number: 12550/6190, 011269. Unpublished 

study prepared by Springborn Laboratories Inc. 46 p. 

48939303 Bergfield, A. (2011) GF-871: Acute Toxicity to the Mysid Shrimp, 

Americamysis bahia, Determined Under the Static-Renewal Test Conditions. 

Project Number: 110061/OCR, 66959. Unpublished study prepared by ABC 

Laboratories, Inc. 49p. 

48939503 Bergfield, A. (2011) GF-2633: Acute Toxicity to the Mysid Shrimp, 

Americamysis bahia, Determined Under the Static-Renewal Test Conditions. 

Project Number: 110058/OCR, 66956. Unpublished study prepared by ABC 

Laboratories, Inc. 50p. 

850.1075 Fish acute toxicity test, freshwater and marine 

46235820 Machado, M. (2002) XDE-750 - Acute Toxicity to Sheepshead Minnow 

(Cyprinodon variegatus) Under Static Acute Conditions. Project Number: 

12550/6191, 011270. Unpublished study prepared by Springborn Laboratories 

Inc. 47 p. 

850.1350 Mysid chronic toxicity test 
Page 43 of 63 

48939305 Dinehart, S. (2011) GF-871: Acute Toxicity to the Sheepshead Minnow, 

Cyprinodon variegatus, Determined Under Static-Renewal Conditions. Project 

Number: 110060/OCR, 66958. Unpublished study prepared by ABC 

Laboratories, Inc. 51p. 

48939402 Wemhoner, U. (2006) GF-1883 - Acute Toxicity to Rainbow Trout 

(Oncorhynchus mykiss) Under Flow-Through Conditions. Project Number: 

060394/OCR, 1072/010/108. Unpublished study prepared by Springborn 

Smithers Laboratories (Europe). 55p. 

48939504 Gerke, A. (2011) GF-2633: Acute Toxicity to the Bluegill Sunfish, Lepomis 

macrochirus, Determined Under Static-Renewal Conditions. Project Number: 

110055/OCR, 66954. Unpublished study prepared by ABC Laboratories, Inc. 

49p. 

48939505 Dinehart, S. (2011) GF-2633: Acute Toxicity to the Sheepshead Minnow, 

Cyprinodon variegatus, Determined Under Static-Renewal Conditions. Project 

Number: 110057/OCR, 66955. Unpublished study prepared by ABC 

Laboratories, Inc. 52p. 

48939203 Hicks, S. (2011) Aminopyralid: Life-Cycle Toxicity Test of the Saltwater Mysid, 

Americamysis bahia, Conducted under Flow-Through Conditions. Project 

Number: 101583, 66018. Unpublished study prepared by ABC Laboratories, Inc. 

84p. 

850.1400 Fish early-life stage toxicity test 

48939204 Hicks, S. (2011) Aminopyralid: Early Life-Stage Test with the Sheepshead 

Minnow, Cyprinodon variegatus, Under Flow-Through Conditions. Project 

Number: 101582, 66015. Unpublished study prepared by ABC Laboratories, Inc. 

79p. 

850.2100 Avian acute oral toxicity test 

46235809 Gallagher, S.; Grimes, J.; Beavers, J. (2003) XDE-750 Technical: An Acute Oral 

Toxicity Study with the Northern Bobwhite. Project Number: 379/130, 031112. 

Unpublished study prepared by Wildlife International, Ltd. 34 p. 

850.2300 Avian reproduction test 

47109901 Temple, D.; Martin, K.; Beavers, J.; et al. (2007) XDE-750 A Reproduction 

Study with the Northern Bobwhite: Final Report. Project Number: 379/176, 

60091. Unpublished study prepared by Wildlife International, Ltd. 157 p. 

850.4225 Seedling emergence, Tier II 

46235824 Aufderheide, J. (2004) Effect of GF-871 on Seedling Emergence and Growth of 

Selected Non-Target Terrestrial Plants (Tier II). Project Number: 48322, 030066. 

Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 89 p. 

850.4250 Vegetative vigor, Tier II 

46235825 Aufderheide, J. (2004) Effect of GF-871 on Vegetative Vigor of Selected NonTarget Terrestrial Plants (Tier II). Project Number: 48323, 030066. Unpublished 

study prepared by Analytical Bio-Chemistry Labs, Inc. 90 p. 

850.5400 Algal toxicity, Tiers 1 and II 
Page 44 of 63 

47109902 Hancock, G.; Arnold, B.; Najar, J.; et al. (2007) Aminopyralid: Growth Inhibition 

Test with the Blue-Green Alga, Anabaena flos-aquae. Project Number: 061150. 

Unpublished study prepared by DOW Chemical Corp. 46 p. 

 Non-Guideline Study 

46235733 Ward, T.; Boeri, R. (2001) XDE-750: 14 Day Soil Exposure Acute Toxicity to the 

Earthworm, Eisenia foetida. Project Number: 2219/DO, 011049. Unpublished 

study prepared by T.R. Wilbury Laboratories, Inc. 34 p. 

46235821 Marino, T.; McClymont, E.; Yaroch, A.; et. al. (2003) Revised Report for XDE750: Toxicity to the Early Life Stages of the Fathead Minnow, Pimephales 

promelas Rafinesque. Project Number: 021029. Unpublished study prepared by 

The Dow Chemical Co. 55 p. 

46235823 Putt, A. (2002) XDE-750 - The Full Life-Cycle Toxicity to Midge (Chironomus 

riparius) Under Static Conditions. Project Number: 12550/6195, 011277. 

Unpublished study prepared by Springborn Laboratories Inc. 88 p. 

46235832 Aufderheide, J. (2001) XDE-750: Acute Oral Toxicity Test with the Honeybee 

(Apis mellifera). Project Number: 46596, 011045. Unpublished study prepared by 

Analytical Bio-Chemistry Labs, Inc. 20 p. 

46235833 Domoradzki, J.; Rick, D.; Clark, A. (2004) XDE-750, Triisopropanolamine Salt: 

Dissociation and Metabolism in Male Fischer 344 Rats. Project Number: 031129, 

2004/8. Unpublished study prepared by The Dow Chemical Co. 57 p. 

 
Page 45 of 63 

Appendix A. Summary of registered products containing aminopyralid and its 

salts.

Table A1. Registered products containing the TIPA salt of aminopyralid 

Registration # Name Status 

Percent Active Ingredient 

Active Ingredient 

% Active Ingredient 

62719-519 MILESTONE Conditionally Registered 

(10-Aug-2005) 40.6 Triisopropanolamine salt of aminopyralid 

62719-524 FOREFRONT 

R&P 

Conditionally Registered 

(22-Nov-2005) 

51.06 2,4-D, triisopropanolamine 

salt 

6.58 Triisopropanolamine salt of 

aminopyralid 

62719-537 MILESTONE VM Conditionally Registered 

(24-Oct-2005) 40.6 Triisopropanolamine salt of aminopyralid 

62719-572 MILESTONE VM 

PLUS 

Conditionally Registered 

(19-Apr-2007) 

2.22 Triisopropanolamine salt of 

aminopyralid 

16.22 Triclopyr, triethylamine salt 

62719-579 GF-2003 Conditionally Registered 

(03-Oct-2007) 

1.5 Triisopropanolamine salt of 

aminopyralid 

51.6 2,4-D, triisopropanolamine 

salt 

62719-587 GRAZONNEXT Conditionally Registered 

(12-Feb-2008) 

6.58 Triisopropanolamine salt of 

aminopyralid 

51.06 2,4-D, triisopropanolamine 

salt 

62719-628 GrazonNext HL Registered (10-Mar-2011) 

8.24 Triisopropanolamine salt of 

aminopyralid 

41.26 2,4-D, dimethylamine salt 

62719-629 PASTURALL HL Registered (10-Mar-2011) 

44.45 2,4-D, triisopropanolamine 

salt 

2 Triisopropanolamine salt of 

aminopyralid 

62719-630 FOREFRONT HL Registered (10-Mar-2011) 

8.24 Triisopropanolamine salt of 

aminopyralid 

41.26 2,4-D, dimethylamine salt 

AL090003 MILESTONE VM Registered (06-Jul-2009) 40.6 Triisopropanolamine salt of 

aminopyralid 

AL120004 MILESTONE Registered (06-Aug-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

AL120007 MILESTONE Registered (17-Jan-2013) 40.6 Triisopropanolamine salt of 

aminopyralid 

AR100004 MILESTONE VM Registered (14-Apr-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

CA130004 MILESTONE Registered (08-Apr-2013) 40.6 Triisopropanolamine salt of 

aminopyralid 

FL110008 MILESTONE VM Under Review (17-Nov2011) 40.6 Triisopropanolamine salt of 

aminopyralid 
Page 46 of 63 

Registration # Name Status 

Percent Active Ingredient 

Active Ingredient 

% Active Ingredient 

FL120002 MILESTONE Registered (31-Jul-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

GA090005 MILESTONE VM Registered (31-Mar-2009) 40.6 Triisopropanolamine salt of 

aminopyralid 

GA120003 MILESTONE Registered (31-Jul-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

GA120007 MILESTONE Registered (13-Dec-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

HI120003 MILESTONE Registered (10-Oct-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

LA120004 MILESTONE Registered (03-Aug-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

LA120020 MILESTONE Registered (05-Mar-2013) 40.6 Triisopropanolamine salt of 

aminopyralid 

MN110004 MILESTONE VM Registered (13-May-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

MN120005 MILESTONE Registered (31-Jul-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

MS090008 MILESTONE VM Registered (31-Mar-2009) 40.6 Triisopropanolamine salt of 

aminopyralid 

MS120008 MILESTONE Registered (06-Aug-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

MS120012 MILESTONE Registered (24-Oct-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

NC090005 MILESTONE VM Under Review (17-Nov2009) 40.6 Triisopropanolamine salt of 

aminopyralid 

NC100004 MILESTONE VM Registered (14-Apr-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

NC120003 MILESTONE Registered (31-Jul-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

NC120010 MILESTONE Registered (01-Nov-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

SC090004 MILESTONE VM Registered (16-Apr-2009) 40.6 Triisopropanolamine salt of 

aminopyralid 

SC110001 MILESTONE VM Registered (05-May-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

TN130002 MILESTONE Registered (30-Apr-2013) 40.6 Triisopropanolamine salt of 

aminopyralid 

TX110002 MILESTONE VM Registered (14-Apr-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

TX120005 MILESTONE Registered (06-Aug-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

TX120014 MILESTONE Registered (13-Dec-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

VA100004 MILESTONE VM Registered (14-Apr-2011) 40.6 Triisopropanolamine salt of 

aminopyralid 

VA110003 MILESTONE VM Under Review (03-May2011) 40.6 Triisopropanolamine salt of 

aminopyralid 
Page 47 of 63 

Registration # Name Status 

Percent Active Ingredient 

Active Ingredient 

% Active Ingredient 

VA120005 MILESTONE Registered (15-Oct-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

VA120006 MILESTONE Registered (18-Oct-2012) 40.6 Triisopropanolamine salt of 

aminopyralid 

Table A2. Registered products containing the potassium salt of aminopyralid 

Registration # Name Status 

Percent Active Ingredient 

Active Ingredient 

% % 

62719-576 GF-1118 Conditionally Registered 

(10-Jul-2007) 88.8 Aminopyralid potassium salt 

62719-597 CHAPARRAL Conditionally Registered 

(23-Jul-2008) 

9.45 Metsulfuron 

62.13 Aminopyralid potassium salt 

62719-617 Opensight WG Registered (03-Aug-2010) 

9.45 Metsulfuron 

62.13 Aminopyralid potassium salt 

62719-645 GF-2791 Registered (15-Feb-2012) 30.82 Clopyralid, 

monoethanolamine salt 

6.02 Aminopyralid potassium salt 

ID090018 OPENSIGHT Registered (05-Mar-2010) 62.13 Aminopyralid potassium salt 

9.45 Metsulfuron 

OR110017 OPENSIGHT Registered (10-Jan-2012) 62.13 Aminopyralid potassium salt 

9.45 Metsulfuron 

WA110011 OPENSIGHT Registered (10-Jan-2012) 62.13 Aminopyralid potassium salt 

9.45 Metsulfuron

Table A2. Registered products containing aminopyralid 

Registration # Name Status Percent Active Ingredient 

% Active Ingredient 

62719-518 AMINOPYRALID 

TECHNICAL 

Conditionally Registered 

(10-Aug-2005) 95.3 Aminopyralid 

62719-525 CLEANWAVE Conditionally Registered 

(02-Dec-2005) 

20.22 Fluroxypyr 1-methylheptyl 

ester 

1.92 Aminopyralid 

FL070003 CLEANWAVE Registered (13-Sep-2007) 20.22 Fluroxypyr 1-methylheptyl 

ester 

FL070003 CLEANWAVE Registered (13-Sep-2007) 1.92 Aminopyralid 

 
Page 48 of 63 

Appendix B. Ecological Model Results 

A. Screening Imbibition Model (SIP; version 1.0) 

Table 1. Inputs 

Parameter Value 

Chemical name Aminopyralid 

Solubility (in water at 25oC; mg/L) 212000 

 

Mammalian LD50 (mg/kg-bw) 5000 

Mammalian test species laboratory rat 

 

Mammalian NOAEL (mg/kg-bw) 1000 

Mammalian test species laboratory rat 

 

Avian LD50 (mg/kg-bw) 2250 

Avian test species mallard duck 

Mineau scaling factor 1.15 

 

Mallard NOAEC (mg/kg-diet) 2623 

Bobwhite quail NOAEC (mg/kg-diet) 2500 

 

Table 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 36464.0000 36464.0000 

Adjusted toxicity value (mg/kg-bw) 3845.8028 769.1606 

Ratio of exposure to toxicity 9.4815 47.4075 

Conclusion* 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

 

Table 3. Avian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 171720.0000 171720.0000 

Adjusted toxicity value (mg/kg-bw) 1168.2572 130.1338 

Ratio of exposure to acute toxicity 146.9882 1319.5654 

Conclusion* 

Exposure through drinking 

water alone is a potential 

concern for birds 

Exposure through drinking 

water alone is a potential 

concern for birds 

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, 

when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water 

may contribute to a total exposure that has potential for effects to non-target animals. 

 
Page 49 of 63 

EFED Screening Tool for Inhalation Risk (STIR, version 1.0)

 

This tool is designed to provide the risk assessor with a rapid method for 

determining the potential significance of the inhalation exposure route to birds 

and mammals in a risk assessment. 

 

Input 

Application and Chemical Information 

Enter Chemical Name Aminopyralid 

Enter Chemical Use 

Is the Application a Spray? (enter y or n) y 

If Spray What Type (enter ground or air) ground 

Enter Chemical Molecular Weight (g/mole) 207 

Enter Chemical Vapor Pressure (mmHg) 1.94E-10 

Enter Application Rate (lb a.i./acre) 0.22 

 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 2250 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 0.178 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 1000 

Enter Lowest Rat Inhalation LC50 (mg/L) 5.5 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.16E-06 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.72E-07 

Adjusted Inhalation LD50 6.90E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.94E-09

Exposure not 

Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.32E-02 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 3.37E-04

Exposure not 

Likely 

Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at Saturation 2.16E-06 
Page 50 of 63 

(mg/m3) 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.41E-07 

Adjusted Inhalation LD50 3.27E+02 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.04E-09

Exposure not 

Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.92E-02 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 8.92E-05

Exposure not 

Likely 

Significant 
Page 51 of 63 

Appendix C. AOPwin output 

SMILES : CLc1c(nc(CL)cc1N)C(=O)O 

CHEM : 

MOL FOR: C6 H4 CL2 N2 O2 

MOL WT : 207.02 

------------------- SUMMARY (AOP v1.92): HYDROXYL RADICALS (25 deg C) -------- 

Hydrogen Abstraction = 0.0000 E-12 cm3/molecule-sec 

Reaction with N, S and -OH = 0.5200 E-12 cm3/molecule-sec 

Addition to Triple Bonds = 0.0000 E-12 cm3/molecule-sec 

Addition to Olefinic Bonds = 0.0000 E-12 cm3/molecule-sec 

Addition to Aromatic Rings = 1.1446 E-12 cm3/molecule-sec 

Addition to Fused Rings = 0.0000 E-12 cm3/molecule-sec 

 OVERALL OH Rate Constant = 1.6646 E-12 cm3/molecule-sec 

 HALF-LIFE = 6.426 Days (12-hr day; 1.5E6 OH/cm3) 

 HALF-LIFE = 77.108 Hrs 

------------------- SUMMARY (AOP v1.91): OZONE REACTION (25 deg C) ----------- 

 ****** NO OZONE REACTION ESTIMATION ****** 

 (ONLY Olefins and Acetylenes are Estimated) 

Experimental Database: NO Structure Matches 
Page 52 of 63 

Appendix D. Maximum or maximum mean amount of applied radioactivity present as a 

specified compound in environmental fate studies submitted on Aminopyralid 

Table D1. Maximum or maximum mean amount of applied radioactivity present as a specified 

compound in environmental fate studies submitted on Aminopyralid.1,2

Compound Study Type 

Max %AR 

(Sampling 

Interval) 

Final %AR 

(Sampling 

Interval) 

Comment MRID 

Parent 

Hydrolysis 

99.8 (0d) 98.6 (32d) pH 5

100 (0d) 101 (31d) pH 7 46235726 

98 (0d) 99 (31d) pH 9 

Aqueous 

Photolysis 92.4 (1h) ND (360h) pH 5 46235727 

Soil Photolysis 105 (0d) 75 (44d) Silt loam 46235728 

Aerobic Soil 

99.7 (0d) 3.8 (365d) Holdredge, 60 g/ha 46235729 102 (0d) 3.7 (365d) Holdredge, 120 

96 (0d) 2.4 (123d) Thessaloniki

47911201 

92 (0d) 52 (123d) Cuckney

92 (0d) 4.2 (92d) Charentilly

93 (0d) 34 (123d) Parabraun, 20oC

98 (0d) 101 (122d) Parabraun, sterile

97 (0d) 78 (123d) Parabraun, 10oC

97 (0d) 46 (123d) Parabraun, 30oC

94 (0d) 46 (126d) Arkansas

92 (0d) 42 (126d) Nebraska 47925801 

96 (0d) 6.5 (59d) Florida 

Aerobic 

Aquatic 

96 (0d) 91 (101d) French sediment

98 (0d) 83 (101d) Italian sediment 46235731 

98 (0d) 90 (101d) US sediment

Anaerobic 

Aquatic

98 (0d) 98 (363d) ND sediment 46235730 100 (0d) 93 (120d) Cuckney soil

Terrestrial 

Field 

Dissipation 

144.2 ng/g (0d) 2.4 (183d) Mississippi 46235734 107.2 ng/g (0d) ND (182d) California 

110.6 g/ha (0d) 3 g/ha 

(121d) New Brunswick 

46235735 

130.3 g/ha (0d) 3.5 g/ha 

(368 d) Ontario 

165.4 g/ha (0d) 9.4 g/ha 

(121d) Manitoba 

151.5 g/ha (0d) 2.8 g/ha 

(123d) Saskatchewan 

113.3 g/ha (0d) ND (372d) Montana 

97.0 g/ha (0d) 6.0 g/ha 

(455d) Alberta 

Aquatic Field 

Dissipation 

32.9 μg/L (0d) ND (120d) Oregon, water 

48939201 

14.6 μg/kg (0d) ND (120d) Oregon, sediment 

32.3 μg/L 0.0181 

(120d) Florida, water 

1.13 μg/kg ND (120d) Florida, sediment 

198 μg/L (0d) 0.28 μg/L 

(120d) Texas, pond water 

48939202 

4.4 μg/kg (14d) 1.6 μg/kg 

(90d)

Texas pond 

sediment
Page 53 of 63 

Compound Study Type 

Max %AR 

(Sampling 

Interval) 

Final %AR 

(Sampling 

Interval) 

Comment MRID 

6.8 μg/kg (7d) -- Texas pond 

crayfish

114 μg/L (0d) 0.27 μg/L 

(120d) Indiana pond wter 

30.1 μg/kg (7d) -- Indiana pond 

sunfish 

3.4 μg/kg (21d) 2.0 μg/kg 

(90d)

Indiana pond 

sediment

8 min (6 

components all 

<10%AR at 10hrs)3

Aqueous 

Photolysis 69 (288h) 67 (360h) pH 5 46235727 

11.5 min3 Aqueous 

Photolysis 2.9 (288h) 2.7 (360h) pH 5 46235727 

16 min3 Aqueous 

Photolysis 3.3 (48h) ND pH 5 46235727 

Unidentified 

Aqueous 

Photolysis 8.7 (8h) 1.5 (360h) pH 5 46235727 

Soil Photolysis 6.9 (44d) 6.9 (44d) Silt loam 46235728 

Anaerobic 

Aquatic 

1 (268d) 0.6 (363d) ND sediment 

46235730 

0.8 (59d) 0 (120d) Cuckney soil 

CO2

Hydrolysis NA NA pH 5,7,9 46235726

Aqueous 

Photolysis 29 (360h) 29 (360h) pH 5 46235727 

Soil Photolysis 3.4 (44d) 3.4 (44d) Silt loam 46235728 

Aerobic Soil 

75 (274d) 70 (365d) Holdredge, 60 g/ha 

46235729 76 (190d) 70 (365d) Holdredge, 120 

g/ha 

68 (92d) 65 (123d) Thessaloniki

47911201 

29 (123d) 29 (123d) Cuckney

69 (92d) 69 (92d) Charentilly

41 (123d) 41 (123d) Parabraun, 20oC

3.2 (122d) 3.25 (122d) Parabraun, sterile

11 (123d) 11 (123d) Parabraun, 10oC

36 (123d) 36 (123d) Parabraun, 30oC

34 (126d) 34 (126d) Arkansas

40 (126d) 40 (126d) Nebraska 47925801 

61 (59d) 61 (59d) Florida 

Aerobic 

Aquatic 

2.7 (101d) 2.7 (101d) French sediment

3.0 (62d) 1.3 (101d) Italian sediment 46235731 

1.2 (101d) 102 (101d) US sediment

Anaeroibic 

Aquatic 

0.7 (268d) 0.6 (363d) ND sediment 46235730 0.4 (120d) 0. (120d) Cuckney soil 

Unextracted 

Residues 

Soil Photolysis 8.0 (44d) 8.0 (44d) Silt loam 46235728 

Aerobic Soil 

13 (63d) 5 (365d) Holdredge, 60 g/ha 46235729 13 (63d) 5 (365d) Holdredge, 120 

20 (123d) 20 (123d) Thessaloniki

47911201 

9 (123d) 9 (123d) Cuckney

21 (61d) 17 (92d) Charentilly

15 (123d) 15 (123d) Parabraun, 20oC

2.3 (122d) 2.3 (122d) Parabraun, sterile
Page 54 of 63 

Compound Study Type 

Max %AR 

(Sampling 

Interval) 

Final %AR 

(Sampling 

Interval) 

Comment MRID 

7.1 (123d) 7.1 (123d) Parabraun, 10oC

12 (123d) 12 (123d) Parabraun, 30oC

13 (126d) 13 (126d) Arkansas

12 (126d) 12 (126d) Nebraska 47925801 

22 (59d) 22 (59d) Florida

Aerobic 

Aquatic 

3.2 (101d) 3.2 (101d) French sediment

15 (101d) 15 (101d) Italian sediment 46235731 

7.0 (101d) 7.0 (101d) US sediment

Anaerobic 

Aquatic 

2.4 (181d) 1.2 (363d) ND sediment

46235730 1.3 (30d) 0.7 (120d) Cuckney soil 

1

 Maximum amounts of organic volatiles were minimal in all studies (<0.1%AR). 

2

 Many of the metabolism studies had multiple unidentified minor degradates that were not identified. 

They were not added together and placed under an unidentified compound(s) list as their presence was 

expected to have little impact on decision making. 

3

 The identity of these residues were not specified; however, two degradates were shown to be oxamic acid 

and malonomic acid. The portion of the oxamic and malonomic acid was not reported. The other 

degradates are expected to be small polar molecules. 

 
Page 55 of 63 

Appendix E. Ecological Incidence Reports
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Dow herbicide that contaminated Green Mountain Compost now effectively banned in 

the Northeast, Kate Robinson Jun. 10, 2013 

http://vtdigger.org/2013/06/10/herbicide-that-contaminated-green-mountain-compostnow-effectively-banned-in-vermont/ (accessed 1/23/2014) 

CSWD: Herbicide contamination in compost extends to bagged products. Matt 

Sutkoski - 

http://www.burlingtonfreepress.com/apps/pbcs.dll/article?AID=/20120706/NEWS02/307

060008/&template=artiphone&nclick_check=1 (accessed 1/23/14)