# Proposed Registration of Aminocyclopyrachlor on Non-Crop Areas, Sod Farms, Turf, and

Residential Lawns

June 16, 2010

U.S. Environmental Protection Agency Office of Pesticide Programs Registration Division

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# Proposed Registration of Aminocyclopyrachlor on Non-Crop Areas, Sod Farms, Tu

.... , and

Residential Lawns

Approved

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Date: Lois Rossi, Director Registration Division

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## TABLE OF CONTENTS

1. REGULATORY RATIONALE ........................................................................................... 4

1.1. C HEMICAL I NFORMATION ............................................................................................. 4

1.1.1. Chemical Name: Aminocyclopyrachlor (parent acid) ..........................................................................4

1.1.2. Chemical Name: Aminocyclopyrachlor-methyl (methyl ester) ............................................................5

1.1.3. Chemical Name: Aminocyclopyrachlor potassium salt ........................................................................5 1.2. H UMAN H EALTH R ISK ................................................................................................... 6

1.2.1. Toxicological Summary and Considerations .........................................................................................6

1.2.2. Toxicological End Points and Doses .....................................................................................................7

1.2.3. Consideration of Toxicity to Children ...................................................................................................8

1.2.4. Dietary Risk

............................................................................................................................... ............9

1.2.5. Residential Risk

............................................................................................................................... ....10

1.2.6. Aggregate Risk

............................................................................................................................... .....11

1.2.7. Occupational Risk

............................................................................................................................... .11 1.3. E NVIRONMENTAL R ISK ................................................................................................ 12

1.3.1. Environmental Summary and Considerations ......................................................................................13

1.3.2. Environmental Fate ..............................................................................................................................1 3

1.3.3. Ecological Risk

............................................................................................................................... .....14 1.4. P UBLIC I NTEREST ......................................................................................................... 16

2. PROPOSED REGULATORY DECISION ...................................................................... 17

2.1. D ATA R EQUIREMENTS ................................................................................................. 17

2.1.1. Human Health Data Requirements ......................................................................................................17

2.1.2. Environmental Data Requirements ......................................................................................................17 2.2. L ABEL R EQUIREMENTS ................................................................................................ 18

2.2.1. Environmental Hazards ........................................................................................................................18

2.2.2. Plant Residue

............................................................................................................................... ........19

2.2.3. Livestock

............................................................................................................................... ..............20

2.2.4. Spray Drift

............................................................................................................................... ............20

2.2.5. Restricted-Entry Interval (REI) ............................................................................................................21 2.3. P ROPOSED R EGISTRATION D ECISION .......................................................................... 21

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## Proposed Registration of Aminocyclopyrachlor on Non-Crop Areas, Sod Farms, Turf, and Residential Lawns

1. REGULATORY RATIONALE

The Agency is proposing to condi tionally grant the first non-food us e registrations of the active ingredient aminocyclopyrachlor, formulated as 2 technical products, 3 manufacturing-use products, and 15 end-use products. It is a selec tive herbicide providing pre- and post-emergent control of broadleaf weeds, woody species, vines, and grasses in non-crop areas [private, public, and military lands: uncultivated non-agricultural ar eas (such as airports, highway, railroad and utility rights-of-way, sewage dis posal areas), uncultivated non-crop agricultural areas (such as farmyards, fuel storage areas, fence rows, non-ir rigation ditchbanks, barrier strips), outdoor industrial sites (such as lumberyards, pipeline, and tank farms), natural areas (such as wildlife management areas, wildlife openings, wildlife habitats, recreation areas, campgrounds, trailheads, and trails)], turf/lawns (residential, industrial, and institutional), golf courses, parks, cemeteries, athletic fields, and sod farms.

Three forms of aminocyclopyrachlor are bei ng proposed for registration: the parent acid (aminocyclopyrachlor), the methyl ester (aminoc yclopyrachlor-methyl), and the potassium salt (aminocyclopyrachlor potassium salt). The parent acid, aminocyclopyrachlor, is considered the active ingredient.

Aminocyclopyrachlor may be applied in three different formulations: gra nular, water dispersible granular (dry flowable), and so luble liquid. Occupational applica tion scenarios include: aerial (fixed wing or helicopter), ground boom, right-of- way sprayer, push-type spreader, push cyclone spreader, tractor drawn broadcast spreader, and lawn care operator (LOC) handgun. Broadcast applications may be performed by using either a single ground boom, a tractor type broadcast, or as a banded application for pre-plant, pre-emer gence, or early post-emergence. Pre-plant applications can be made as either a single or sp lit application that is ei ther surface applied or incorporated. Residential a pplication scenarios include lo w pressure hand wand, hose-end sprayer, and hand-held spreader (i.e. belly grinder). Proposed maximum annual application rates range from 0.05 – 0.324 lb acid e quivalent (ae)/acre/year.



### 1.1. Chemical Information

Aminocyclopyrachlor is a systemic herbicide in the pyrimidine carboxylic aci ds class within the family of synthetic auxins, which disrupts gene expression resulting in undifferentiated cell division and elongation. It is biologically active in soil a nd is rapidly absorbed by roots and leaves. Effects to target w eeds include downward bending of l eaves, severe necrosis, stem thickening, growth stunting, leaf crinkling and cuppi ng, calloused stems and leaf veins, and enlarged roots. Symptoms may begin from a fe w hours to a few days after application, and plant death may take weeks to several months.

1.1.1. Chemical Name: Aminocyclopyrachlor (parent acid)
6-amino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylic acid

- 4 -EPA PC Code: 288008

CAS Number: 858956-08-8

Mode of Action: Synthetic auxin-type herbicide causing disorganized plant growth (pyrimidine carboxylic acid) Registrant: E.I. du Pont de Nemours and Co mpany (EPA Company Number: 352)

Products: EPA Reg. No. Product Name % a.i. 352-TIE (782) DPX-MAT28 Technical Herbicide 89.3 352-TOA (796) DPX-MAT28 10% Ma nufacturing Concentrate 10.0 352-TIT (787) DPX-MAT28 50SG Herbicide 50.0 352-TOU (794) DPX-MAT28 50SG Turf Herbicide 50.0 352-IRG (813) DPX-MAT28 0.05G Turf Herbicide + Fertilizer 0.05 352-IRU (814) DPX-MAT28 0.03G Turf Herbicide + Fertilizer 0.03 352-IRL (815) DPX-MAT28 0.068G Lawn Herbicide + Fertilizer 0.068

1.1.2. Chemical Name: Aminocyclopyrachlor-methyl (methyl ester)
methyl 6-am ino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylate

EPA PC Code: 288009

CAS Number: 858954-83-3

Mode of Action: Synthetic auxin-type herbicide causing disorganized plant growth (pyrimidine carboxylic acid) Registrant: E.I. du Pont de Nemours and Co mpany (EPA Company Number: 352)

Products: EPA Reg. No. Product Name % a.i. 352-TIG (783) DPX-KJM44 Technical Herbicide 95.6 352-TIU (784) DPX-KJM44 80 MUP Herbicide 80.0 352-TOL (795) DPX-KJM44 10% Ma nufacturing Concentrate 10.0 352-TIL (785) DPX-KJM44 80XP Herbicide 80.0 352-TOE (792) DPX-KJM44 80XP Turf Herbicide 80.0 352-TOT (797) DPX-KJM44 0.064G Turf Herbicide + Fertilizer 0.064 352-INN (800) DPX-KJM44 0.073G Lawn Herbicide + Fertilizer 0.073 352-ING (803) DPX-KJM44 0.053G Lawn Herbicide + Fertilizer 0.053 352-INU (804) DPX-KJM44 0.049G Lawn Herbicide + Fertilizer 0.049 352-INT (807) DPX-KJM44 0.033G Lawn Herbicide + Fertilizer 0.033 352-IRR (811) DPX-KJM44 0.02G Lawn Herbicide + Fertilizer 0.02

1.1.3. Chemical Name: Aminocyclopyrachlor potassium salt
potassium 6-amino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylate

EPA PC Code: 288010

CAS Number: 858956-35-1

Mode of Action: Synthetic auxin-type herbicide causing disorganized plant growth

- 5 -(pyrimidine carboxylic acid) Registrant: E.I. du Pont de Nemours and Co mpany (EPA Company Number: 352)

Products: EPA Reg. No. Product Name % a.i. 352-TIA (786) DPX-MAT28 240SL Herbicide 25.0 352-TOG (793) DPX-MAT28 240SL Turf Herbicide 25.0



### 1.2. Human Health Risk

A summary of the human health effects and risk of aminocyclopyrachlor as assessed in the Agency document titled “Aminocyclopyrachlor: Human Health Risk Assessment for Proposed Uses as an Herbicide” is provided below.

1.2.1. Toxicological Summary and Considerations

Pharmacokinetic oral studies in dicate that both aminocycl opyrachlor and aminocyclopyrachlormethyl are rapidly absorbed, with rapid metabol ic conversion of aminocyclopyrachlor-methyl to aminocyclopyrachlor. Elimination is almost comp lete within 24 hours. Similar acute toxicities, subchronic dietary, reproductive toxi city, and gene mutation studies results for both chemicals, along with evidence from metabolism studies form a scientific justification for considering aminocyclopyrachlor and aminocyclopyrachlor-methyl toxicologica lly equivalent, thus allowing bridging of the toxicity database for am inocyclopyrachlor-methyl with studies using aminocyclopyrachlor.

The toxicology database for am inocyclopyrachlor is adequate for risk assessment for the proposed use patterns. Aminocyclopyrachlor ha s low acute toxicity by oral, dermal, and inhalation routes of exposure, and does not cause skin sensitization or irritation. However, it can cause mild eye irritation. Aminocyclopyrach lor and aminocyclopyrachlor-methyl have low subchronic toxicity via the oral r oute. The most sensitive specie s is the rat, with decreased body weight at the limit dose in subchr onic dietary studies as the most sensitive endpoint of toxicity. The major effect observed across species for ami nocyclopyrachlor was decr eased body weight at the limit dose. No toxicity was observed in subc hronic dietary studies in dogs at the highest dose of aminocyclopyrachlor tested, wh ich was half the limit dose, but still higher than the dose at

which no adverse effects occurred in the rat. No target organ of toxicity was identified. No sex differences in toxicity were observed for e ither aminocyclopyrachlor or aminocyclopyrachlormethyl.

Aminocyclopyrachlor was not neurotoxic when admi nistered acutely or subchronically via the oral route. Aminocyclopyrachlor-methyl showed no evidence of neurotoxicity or reproductive toxicity in an extended one ge neration reproductive toxicity st udy in rats. Aminocyclopyrachlor did not cause developmental toxic ity in rats or rabbits. Therefore, there is low concern for reproductive, developmental, or neur otoxicity for aminocyclopyrachlor and aminocyclopyrachlor-methyl.

- 6 -Aminocyclopyrachlor and aminocycl opyrachlor-methyl are considered to have low potential to cause chronic toxicity or carci nogenicity. No evidence of genotoxic effects was observed in mutagenicity studies in vitro for aminocyclopyrachlor and aminocyclopyrachlor-methyl or in

vivo for aminocyclopyrachlor. No evidence of ta rget organ toxicity was observed in oral subchronic studies for aminocyclopyrachlor and aminocyclopyrachlor-methyl at doses exceeding

the limit dose.

Immunotoxicity was investigated via the oral route in two species (rats and mice) for aminocyclopyrachlor. There was no evidence of immunotoxicity.

1.2.1.1. Degradate of Concern

An environmental photodegradate of aminocyclopyr achlor present only in surface water was of possible concern for drinking wa ter exposures. This photodegrad ate, cyclopropane carboxylic acid (IN-V0977), has a different mode of toxi c action than aminocyc lopyrachlor. Oral administration of cyclopropane carboxylic acid causes severe impair ment of mitochondrial function by inhibiting the beta oxidation of fatty acids, resulting in microvesicular steatosis (accumulation of small fat droplets in cells). The liver is the most sensitive organ, and hepatocellular microvesicular stea tosis is often accompanied by liver necrosis and inflammation, decreased hepatic glycogen, and decreased blood glucose levels. These effects have been observed with acute (one to three days) and longer (up to 14 days) exposure. The most sensitive species is the rabbit. Hepatic microvesicular steatosis in the rabbit follows a different doseresponse than body weight decreases obs erved with aminocyclopyrachlor and aminocyclopyrachlor-methyl in rats, with a lowest observed adverse effect level (LOAEL) that is 100-fold lower. However, based on the propos ed use pattern, the dietary exposure to IN-V0977 from drinking water is below the Agency’s level of concern (LOC) (see Section 1.2.4).

1.2.2. Toxicological End Points and Doses

1.2.2.1. Acute Dietary

For aminocyclopyrachlor, no acute reference dos e (aRfD) or acute population adjusted dose (aPAD) was established because no toxicity wa s observed at the limit dose in the acute oral toxicity studies.

For the degradate IN-V0977, the Agency has established an aRfD of 0.0026 mg/kg (body wt)/day, based on the LOAEL of 2.55 mg/kg/day from a rabbit st udy in which hepatic steatosis was observed and an uncertainty factor of 1000X. The 1000X un certainty factor takes into account interspecies and intraspe cies variability (10X for each ) as well as the uncertainty associated with extrapolation of a no observe d adverse effect level (NOAEL) from a LOAEL (10X).

1.2.2.2. Chronic Dietary

For aminocyclopyrachlor, the Agency has establ ished a chronic reference dose (cRfD) and a chronic population adjusted dose (cPAD) of 0.35 mg/kg/da y, based on the NOAEL of 350

- 7 -mg/kg/day from the 90-day oral toxi city study in rats and an uncertain ty factor of 1000X. In this study, decreased body weights, body weight gains, food consumption, and food efficiency in

both sexes were observed at the LOAEL of 1044.6/1424.9 mg/kg/day. The 1000X uncertainty factor takes into account interspe cies and intraspecies variability (10X for ea ch) as well as the uncertainty associated with using an endpoi nt from a subchronic study to assess chronic exposure (10X).

For the degradate IN-V0977, the Agency has esta blished a cRfD of 0.00087 mg/kg/day, based on the LOAEL of 2.55 mg/kg/day from a rabbit study in which hepa tic steatosis was observed and an uncertainty factor of 3000X. The 3000X uncertainty factor ta kes into account interspecies and intraspecies variability ( 10X for each), uncertainty associ ated with extrapolation of a NOAEL from a LOAEL (10X), and uncertainty aris ing from using a short-term study to assess long-term risk (3X).

1.2.2.3. Short- and Intermediate-Term In cidental Oral and Inhalation

The Agency has established a LOC of 3.5 mg/kg/ day for the margin of exposure (MOE) of 100, based on the NOAEL of 350 mg/kg/day from the chr onic 90-day oral toxic ity study in rats and an uncertainty factor of 100X (10X interspecies x 10X intras pecies). In this study, decreased body weights, body weight gains, food consumption, and food efficiency in both sexes were observed at the limit dose LOAEL of 1044.6/1424.9 mg /kg/day. Long-term incidental oral exposures are not anticipated ba sed on the proposed use pattern.

1.2.2.4. Short- and Intermediate-Term Dermal

No dermal endpoint was established because no t oxicity was observed at the limit dose in the 28- day dermal toxicity study. The 90-day dermal toxicity study was waived because the 28-day dermal toxicity study is consider ed suitable for long-term exposures and all endpoints of concern

were assessed.

1.2.2.5. Cancer

The Agency has classified aminocyclopyrachlor as “Not likely to be Ca rcinogenic to Humans” based on the lack of evidence of genotoxic effects in the in vitro and in vivo mutagenicity studies. Aminocyclopyrachlor is considered to have low potential to cause chronic toxicity or carcinogenicity. No evidence of ta rget organ toxicity was observed in oral subchronic studies at doses exceeding the limit dose. Theref ore, cancer risk was not assessed.

1.2.3. Consideration of Toxicity to Children

Food Quality Protection Act (FQPA) considerations do not apply to aminocyclopyrachlor for the non-food use patterns described in this risk assessment. However, the Agency has reviewed the toxicity database and has determined that the young will not be particularly sensitive to the effects of aminocyclopyrachlor when used in residential settings based on the following:

• The toxicity database is c onsidered complete and includes acceptable developmental

- 8 -toxicity studies in rats and rabbits, a two-generation reproduc tive toxicity study in rats, and an extended one-generation reproductive toxicity study in rats that included a modified functional observational battery.

• No evidence of neurotoxicity was observed in the acute or subchronic neurotoxicity

studies in rodents at the limit dose after exposure to aminocyclopyrachlor. Also, no evidence of neurotoxicity was observed in an extended one-generation reproduction study in rats with aminocyclopyrachlor-methyl that included a modified functional observational battery.

• No evidence of developmental toxicity was observed when aminocyclopyrachlor was administered in the diet of rats or orally by gavage to rabbits at the limit dose.

• No evidence of adverse effects of aminoc yclopyrachlor or ami nocyclopyrachlor-methyl on reproduction or fertility parameters was observed in dietary studies with rats.

• No evidence of prenatal toxicity was observed following maternal exposure to aminocyclopyrachlor. There is no eviden ce of increased susceptibility following in utero exposure to aminocyclopyrachlor in rats or ra bbits in developmenta l toxicity studies, which showed no adverse effects in offspring at the limit dose. An increase in abortions

in maternal rabbits was observed at the limit dose, but this was considered secondary to decreases in body weight. There was also no evidence of increased susceptibility of offspring to aminocyclopyrachlor in reproductio n and fertility studies in rats, for which

adverse effects were limited to decreased body weights in both maternal animals and offspring at the limit dose. Therefore, the young are not considered more susceptible

than adults to adverse effects from aminoc yclopyrachlor or aminocyclopyrachlor-methyl.

• There are no residual uncertainties identifie d in the exposure databases. EPA made conservative (protective) assumptions in th e ground and surface water modeling used to assess exposure to aminocyclopyrachlor in drinking water. EPA used similarly conservative assumptions to assess post-a pplication exposure of children including incidental oral exposure of toddlers. These assessments will not underestimate the exposure and risks posed by aminocyclopyrachlor.

1.2.4. Dietary Risk

Dietary risk assessment addresses exposure that individuals receive through food consumption and drinking water. Since there are no proposed food uses for aminocyclopyrachlor, only dietary exposure to aminocyclopyrachlor and its environm ental degradates from drinking water were

considered.

For aminocyclopyrachlor, no acute dietary risk assessment was perf ormed since no acute toxicity endpoint was identified. Cancer risks from dietary exposure to aminocyclopyrachlor and the degradate IN-V0977 in drinking water were not assessed since no cancer dietary endpoint was

identified. Risks for chronic dietary exposures to aminocyc lopyrachlor from drinking water were considered, and the risk estimates for the general U.S. population and all other regulated population subgroups are below the Agency’s LOC of greater than 100% of the cRfD. Chronic exposure to aminocyclopyrachlor fro m drinking water will occupy <1% of the cRfD for infants less than 1 year old, the popul ation subgroup with the highest estimated exposure.

- 9 -The major route of environmental degradation of aminocyclopyrachlor is aqueous photolysis, which produces five degradates. Of thes e, one environmental degradate, IN-V0977 (cyclopropane carboxylic acid), was of concern. Dietary assessments of acute and chronic dietary exposures of cyclopropane carboxylic aci d from drinking water were performed, and are below the Agency’s LOC of greater than 100% of the aRfD/cRfD. Acute exposure to the degradate IN-V0977 from drinking water will occ upy 13% of the aRfD and 9.9% of the cRfD for infants less than 1 year old, the population s ubgroup with the highest estimated exposure.

1.2.5. Residential Risk

Residential risk assessment addresses exposures that individuals receiv e through their use of consumer products and exposures th at individuals receive from fre quenting areas that have been previously treated with aminocyclopyrachlor.

1.2.5.1. Residential Handler Risk

Residential handler exposure to aminocyclopyrachlor may occur dermally and by inhalation. No dermal risk was assessed because no toxicity was observed at the limit dose in the subchronic dermal toxicity study. Inhalation risk was assesse d by analysis of short-term and intermediateterm exposures using the lawn/turf products with the highest applicati on rates (0.07 - 0.10 lb ae/A) and hazards identified in subc hronic oral toxici ty studies.

The Agency has identified the following residen tial exposure scenarios fr om applications to

lawns/turf:

Mixing/Loading/Applying

• Low Pressure Handwand (dry flowable and soluble liquid)

• Hose-End Sprayer (dry flowable and soluble liquid)

• Hand-Held Spreader/Belly Grinder (granular)

The margins of exposure (MOEs) for the thr ee inhalation exposure scenarios range from 7,300,000 to 41,200,000. Since the Agency’s LOC is for MOEs less than 100, residential handler exposures are not of concern.

1.2.5.2. Residential Post-Application Risk

Residential post-application expos ure to aminocyclopyrachlor may occur dermally and orally for a variety of populations. No dermal risk was assessed because no toxicity was observed at the limit dose in the subchronic dermal toxicity study. Oral risk in toddlers was assessed by analysis of short-term and intermediate-term post-appli cation exposures using th e lawn/turf product with the highest application ra te (0.10 lb ae/A).

The Agency has identified the following residen tial post-application ex posure scenarios from applications to lawns/turf:

Toddlers

- 10 -• Hand-to-Mouth Activity on Lawn/Turf

• Object-to-Mouth Activity on Lawn/Turf

• Soil Ingestion

The single and combined MOEs for short-term a nd intermediate-term oral exposures range from 234,000 to 70,000,000. Since the Agency’s LOC is for MOEs less than 100, residential postapplication exposures are not of concer n for any population, including toddlers.

1.2.6. Aggregate Risk

Aggregate risk assessment addres ses combined exposures that i ndividuals receive from dietary and residential exposures to aminocyclopyrachl or. Quantitative, aggreg ate exposure and risk assessments for aminocyclopyrachlor are not re quired for the proposed non-food use patterns because Food Quality Protection Act (FQPA) c onsiderations do not apply. However, the potential for significant aggreg ate exposures to aminocyclopyr achlor from dietary (drinking water) and residential uses rela tive to non-aggregate exposures was considered. The highest estimated residential exposure (0.000048 mg/kg/ day via inhalation during mixing, loading, and applying a granular formulation with a belly grinder) was combin ed with the highest estimated dietary exposure (0.002778 mg/kg/da y for all infants < 1 year old) . This combined value of 0.003 mg/kg/day was over 1000- fold lower than th e point of departure of 3.5 mg/kg/day, based on the most conservative LOC for MOE (350 mg /kg/day with MOE =100). This estimate indicates that aggregate expos ures to aminocyclopyrachlor wi ll not result in significantly

increased risk relative to non-aggregate exposure.

1.2.7. Occupational Risk

Occupational risk assessment addresses ri sks to individuals who are exposed to aminocyclopyrachlor as part of their employment, via contact while using commercial products (handler) or by being in areas that have been previously treated (post-application).

1.2.7.1. Occupational Handler Risk

Occupational handler exposure to aminocyclopyrach lor may occur dermally and by inhalation. No dermal risk was assessed because no toxicity was observed at the limit dose in the subchronic dermal toxicity study. Inhalation risk was assesse d by analysis of short-term and intermediateterm exposures using the products with the hi ghest application rates (0.07 - 0.28 lb ae/A) and

hazards identified in subchronic oral toxicity studies.

The Agency has identified the following occupati onal exposure scenarios fr om applications to private, public and military lands including un-cu ltivated non-agricultural (non-crop) areas such as airports, highways, railroads, golf courses, lu mber yards, wild life habitats, multi family residential complexes, recreation ar eas, sod farms, utility rights of way, and residential lawns:

Mixing/Loading

• Groundboom (dry flowable and soluble liquid) to non-crop areas, golf courses, sod farms, and lawn/turf

- 11 -• Aerial (fixed and non-fixed wing) (dry flowable) to non-crop areas

• LCO handgun (dry flowable and soluble liqui d) to non-crop areas, golf courses, sod farms, and lawn/turf

• Right-of-way sprayer (dry flowable and soluble liquid) to non-crop areas, golf courses, sod farms, and lawn/turf

• Push-type spreader (granular) to golf courses, sod farms, and lawn/turf

• Tractor drawn broadcast spread er (granular) to golf course s, sod farms, and lawn/turf

• Push cyclone spreader (granular) to gol f courses, sod farms, and lawn/turf

Applying

• Groundboom (dry flowable and soluble liquid) to non-crop areas, golf courses, sod farms, and lawn/turf

• Aerial (fixed and non-fixed wing) (dry flowable) to non-crop areas

• LCO handgun (dry flowable and soluble liqui d) to non-crop areas, golf courses, sod farms, and lawn/turf

• Right-of-way sprayer (dry flowable and soluble liquid) to non-crop areas, golf courses, sod farms, and lawn/turf

• Tractor drawn broadcast spread er (granular) to golf course s, sod farms, and lawn/turf

Flagging

• Aerial (fixed and non-fixed wing) (dry flowable) to non-crop areas

The MOEs for the identified inhalation e xposure scenarios range from 190,000 to 50,000,000. Since the Agency’s LOC is for MOEs less than 100, occupational handler exposures are not of

concern.

1.2.7.2. Occupational Post-Application Risk

Occupational post-application exposure to aminocyclopyrachlor may occur dermally and by

inhalation. No dermal risk was assessed because no toxicity was observed at the limit dose in the subchronic dermal toxicity study. A quantitative post-application inhalation risk assessment was not deemed necessary, based on the high occupa tional handler MOE values. Post-application exposures would be lower than those for handl ers due to aminocyclopyrachlor’s low vapor pressure and dilution in outdoor ai r. Therefore, occupational pos t-application e xposures are not
of concern.



### 1.3. Environmental Risk

A summary of the environmental fate and ecologi cal effects and risks of aminocyclopyrachlor as assessed in the Agency document titled “Ecol ogical Risk Assessment for the Section 3 New Chemical Registration of Aminocyclopyrachlor on Non-crop Areas and Turf” is provided below.

- 12 -1.3.1. Environmental Summary and Considerations

A dissociation constant study i ndicated that the potassium sa lt form of aminocyclopyrachlor rapidly dissociates to the acid when it is mixed with water prior to application. This similarity in behavior once the potassium salt is dissociated in water allows br idging of the environmental fate and toxicity database for aminocyclopyr achlor potassium salt with studies using aminocyclopyrachlor.

Laboratory and field dissipati on studies indicated that ami nocyclopyrachlor-methyl rapidly hydrolyzes to aminocyclopyrachlor in alkaline aq uatic environments, moist soils, and soil/water slurries. Degradation under environmentally-re levant pH conditions is primarily microbe mediated. Therefore, aminocyclopyrachlor-me thyl applications may result in short-term exposures to the methyl ester form prior to hydrol ysis to the acid. Aqua tic studies on freshwater fish and invertebrates for aminocyclopyrachlor-methyl showed higher toxicity than aminocyclopyrachlor. As a result, with the exception of acute a quatic toxicity data,

acute/chronic terrestrial a nd chronic aquatic toxicity data may be bridged for aminocyclopyrachlor-methyl with st udies using aminocyclopyrachlor.

1.3.1.1. Degradates of Concern

Model estimates suggest that degradates IN -LXT69 and IN-YY905 may be more toxic than aminocyclopyrachlor to daphnids on a chronic basis. Based on human health effects evaluation of degradates (see Sections 1.2.1.1 and 1.2.4), the degradate IN-V0977 may be more toxic than aminocyclopyrachlor to birds and mammals. However, by comparing the concentrations expected in the environment to the effects thre sholds, IN-V0977 would have to be more than two orders of magnitude more toxic than aminocyc lopyrachlor to exceed the Agency’s LOC. Also, since aqueous photolysis is the only si gnificant rapid degradation pathway of aminocyclopyrachlor, aquatic exposur e to the three degradates of c oncern would not result in any additional risks over those presented from exposure to aminocyclopyrachlor unless the degradates were considerably more toxic.

1.3.2. Environmental Fate

Aminocyclopyrachlor is non-volatile, highly soluble in water, and highly mobile to mobile in soils. Dissipation in the environment is expect ed to occur predominantly via aqueous photolysis, runoff, and leaching. Terrestrial field dissipation occurred with half-lives ranging from 22 to 126 days. Aminocyclopyrachlor was detected at so il depths of 70 – 90 cm at 365 days, indicating that leaching of residues into groundwater may occur.

Aminocyclopyrachlor is environmentally persistent in diverse environments. It persists in aerobic aquatic environments with a dissipation time of greater than 100 days and in aerobic

terrestrial environments with a half-life of 373 days. It is al so stable in anaerobic aquatic environments with a half life of 1733 days and in anaerobic terrestrial envi ronments with a halflife of 6932 days. It has a low tendency for bioaccumulation.

- 13 -The major route of degradation of aminocyclopyr achlor is abiotic via aq ueous photolysis with a half-life of l.2 days in shallow, clear, and well-lit natural (pH 6.2) water bodies and 7.8 days in pH 4 buffer solution. However, it is slowly phot olyzed on soil, with a half-life of 129 days. Aminocyclopyrachlor is stable to hydrolysis at pH 4, 7, and 9.

To address concerns with the potential leaching of aminocyclopyrachlor that may result from the persistence and mobility described above, end-us e product labels will be required to include surface and ground water advisories that stress the potential of runoff after treatment and descriptions of conditions that may promote leaching to groundwater (see Section 2.2.1).

1.3.3. Ecological Risk

Ecological risk assessment addresses exposures th at non-target aquatic a nd terrestrial organisms and plants receive through the use of aminocyclopyrachlor.

A screening-level risk assessment based on proposed uses suggests that aminocyclopyrachlor presents potential risk to terrestrial and semi-a quatic plants and to organisms that depend on the plants for habitat and forage.

To better characterize and confirm chronic risks to birds and freshwater in vertebrates, additional data will be required as a condi tion of registration (see Section 2.1.2). To mitigate potential risk to non-target terrestrial and semi-aquatic plants , end-use product labels will be required to include language that is intended to keep the pesticide on the treatment area (see Section 2.2.4).

1.3.3.1. Aquatic Risk

The highest surface water estimated environmenta l concentration (EEC) values resulted from proposed aerial non-crop applications at 0.284 lb ae/ A. This conservative approach of using an EEC of 0.284 lb ae/A will also cover turf appli cations, which resulted in lower EECs. EECs were compared to toxicity endpoi nts to derive risk quotients (RQs ), which is then compared to the Agency’s LOC.

1.3.3.1.1. Fish Risk

Aminocyclopyrachlor is practically non-toxic to freshwater and estu arine/marine fish on an acute basis. Acute risk was not quantified since no toxi city was observed at the highest concentration tested; therefore, RQs are not expected to ex ceed LOCs. Aminocyclopyrachlor-methyl is slightly toxic to freshwater fish on an acute basis; however, the RQ of <0.01 does not exceed the

LOC. Chronic risk to freshwater fish resulted in a RQ of <0.01 and does not exceed the LOC.

1.3.3.1.2. Aquatic Invertebrate Risk

Aminocyclopyrachlor and aminoc yclopyrachlor-methyl are sli ghtly toxic to freshwater invertebrates on an acute basis; however, RQs of <0.01 do not exceed LOCs. Aminocyclopyrachlor is practically non-toxic to estuarine/marine i nvertebrates on an acute basis;

- 14 -where the RQ <0.01 does not exceed the LOC.

In the chronic freshwater i nvertebrate (daphnid) study, non dos e-response mortalities were

observed at the three lowest treatment levels. Th erefore, the resulting to xicity values could not be used quantitativel y to assess chronic risk to aquatic invertebrates. Despite the lack of valid data, chronic risk to freshwater invertebrates is not expected to exceed the Agency’s LOC. Environmental concentrations of aminocyclopyrach lor in surface waters from applications at the proposed maximum rates are expected to be in the parts per billion (ppb) range; whereas all aquatic toxicity studies were c onducted at concentrations in th e parts per million (ppm) range.

Based on the results of chronic studies in freshw ater fish, where the no observed adverse effect concentration (NOAEC) is 11 ppm, EPA also exp ects the freshwater invertebrate NOAEC to be in the ppm range, well above the expected environm ental concentrations. A repeated Freshwater Invertebrate Life Cycle Toxicity Test (Guideline 8 50.1300) is expected to be confirmatory and will be required as a condition of registration (see Section 2.1.2).

1.3.3.1.3. Aquatic Plant Risk

Risks to aquatic vascular and non-vascular plan ts resulted in RQs <0.01, which do not exceed the Agency’s LOC.

1.3.3.2. Terrestrial Risk

Terrestrial wildlife EECs are estimated empha sizing a dietary exposure route for uptake of pesticide residues on vegetative matter and insects. Birds are used as su rrogates for terrestrialphase amphibians and reptiles. Honey bee is used as a surrogate for terrestrial invertebrates.

1.3.3.2.1. Avian Risk

Aminocyclopyrachlor and aminocyc lopyrachlor-methyl are practica lly non-toxic to birds (also terrestrial-phase amphibians and reptiles) on an ac ute basis. Acute risk was not quantified since no toxicity was observed; therefore, RQs are not expected to exceed LOCs.

The submitted avian reproduction studies were invalid due to improper husbandry practices (small cage sizes) that may have caused incide ntal mortalities in quails and reduced egg production in mallards. Despite the improper husbandry conditions, there was no evidence in either study of adverse treatment-related effects, including overt toxicit y, mortality, effects on feed consumption and body weight, macr oscopic findings, or reproductive effects. A repeated Avian Reproduction Toxicity Test (Guideline 850.2300) is expected to be confirmatory and will be required as a condition of registration (see Section 2.1.2).

1.3.3.2.2. Mammalian Risk

Aminocyclopyrachlor and aminocyc lopyrachlor-methyl are practica lly non-toxic to mammals on an acute basis. Acute risk was not quantified since no toxicity was observed; therefore, RQs are not expected to exceed LOCs. Chronic risks to mammals resulted in RQs of <0.1 and do not

exceed the LOC.

- 15 -1.3.3.2.3. Terrestrial Invertebrate Risk

Aminocyclopyrachlor is practically n on-toxic to terrestrial invertebra tes, due to lack of mortality and sublethal effects in the honey bee study for aminocyclopyrachlor. An acute earthworm toxicity study for aminocyclopyrachlor-methyl also showed no mortalities or behavioral abnormalities, but the study is classified as s upplemental since the Agency does not currently have an OPPTS guideline for earthworms. Th e Agency does not routinely quantify risks to

terrestrial invertebrates.

1.3.3.2.4. Terrestrial Plant Risk

As expected for herbicides, terrestrial and semi-aquatic plants are sensitive to aminocyclopyrachlor, where RQs exceeded the LOC. Non-target terrestrial and semi-aquatic plants may be exposed to aminocyclopyrachlor via runoff and spray drift, with dicots being more susceptible than monocots. To mitigate potential risk to non-target terre strial and semi-aquatic plants, end-use product labels will be required to include language that is intended to keep the pesticide on the treatment area (see Section 2.2.4).



### 1.4. Public Interest

Aminocyclopyrachlor poses very low risk to humans, including workers and the general population, due to its low toxicity and low volatility. Similarly, be cause of its low toxicity to terrestrial and aquatic non-target organisms other than pl ants, aminocyclopyrachlor poses low

environmental risks.

The benefits afforded by registration of aminoc yclopyrachlor may be subs tantial. Along with other herbicides in the same chemical family, th is herbicide will be an important component in integrated pest management programs for both non-crop and turf areas. Aminocyclopyrachlor controls a broad spectrum of weeds, including difficult to manage invasive and noxious brush and herbicide-resistant species. In particul ar, aminocyclopyrachlor demonstrates very good long-term control of Leafy Spurge, considered one of the most difficult to control invasive weeds in the western United States. Leafy Spurge is listed as a noxious weed in 22 states, making control mandatory by legal statut e in those areas. Very few alternative chemicals provide effective long-term control of Leafy Spurge, wh ich reproduces aggressively, actively destroying native biodiversity and rendering pastures and rangelands unfit for cattle and horses grazing due to its unpalatability and toxicity. A single app lication of aminocyclopyrachlor will provide longlasting control, obviating the need for multiple applications of the cu rrent alternatives and thereby reducing the pesticide load in the environment. Aminocyc lopyrachlor will also provide the commercial turf industry with an important t ool. Because of its low vol atility, it can be used in turf applications around valuable ornamental pl ants with less risk of damage than the current staples of the industry, 2,4-D and dicamba.

Based on these considerations, the Agency believ es that the registration of aminocyclopyrachlor is in the public’s interest.

- 16 -

### 2. PROPOSED REGULATORY DECISION

The Agency is proposing to grant the first registrations of the active ingredient aminocyclopyrachlor, formulated as 2 technical products, 3 manufacturi ng-use products, and 15 end-use products. It is a selective herbic ide providing pre-emergence and post-emergence control of broadleaf weeds, woody species, vines, and grasses in non-crop areas [private, public, and military lands: uncultivated non-agricultural areas (airports, highway, railroad and utility rights-of-way, sewage disposal areas), uncultivat ed non-crop agricultural ar eas (farmyards, fuel storage areas, fence rows, non-irrigation ditchbanks , barrier strips), out door industrial sites (lumberyards, pipeline, and tank farms), natura l areas (wildlife management areas, wildlife openings, wildlife habitats, recr eation areas, campgrounds, trailhead s, and trails)], turf/lawns (residential, industrial, and instit utional), golf courses, parks, cemeteries, at hletic fields, and sod

farms.

In the Federal Register of January 27, 2010 ( 75 FR 4384), EPA issued a notice pursuant to section 3(c)(4) of FIFRA entitled “Pesticide Prod ucts; Registration Applic ations” in the docket EPA-HQ-OPP-2009-0789 announcing receipt of applica tions to register pesticide products containing the new active ingredient, aminocycl opyrachlor, by E.I. du Pont de Nemours and Company. There were no comments received in response to the notice of receipt.



### 2.1. Data Requirements

The Agency has determined that additional data ar e required in order to better characterize risk. The studies identified below will be require d as a condition of the registration of aminocyclopyrachlor.

2.1.1. Human Health Data Requirements

The human health risk assessmen t concluded that the following study is required in support of the proposed uses:

• A repeated-dose study in a sensitive species is required to address the hazard of subchronic/chronic exposure to the envi ronmental degradate cyclopropane carboxylic acid (IN-V0977): To account for the lack of this study, EPA applied an additional 3X uncertainty factor (UF) to the point of de parture (POD) used in the chronic exposure assessment for drinking water. Even w ith the additional UF and the conservative assumptions of the drinking water models used to estimate concentrations of aminocyclopyrachlor in drinking water, esti mated chronic risk is well below the LOC (<10% of the cPAD for all population groups).

2.1.2. Environmental Data Requirements

- 17 -The ecological risk assessment concluded that th e following studies are re quired in support of the proposed uses:

• Avian Reproduction Toxicity Test (850.2300) : Data are required for both an upland game and waterfowl species for the proposed use patterns. The submitted studies were inva lid due to improper husbandry practices that may have caused incidental mortalitie s in quails and reduced egg production in mallards. Despite the improper husbandry c onditions, there was no evidence in either study of adverse treatment-rela ted effects, including overt toxi city, mortality, effects on feed consumption and body weight, macros copic findings, or reproductive effects. Therefore, submission of a repeat-study pe rformed under proper husbandry conditions is expected to be confirmatory and will better c haracterize chronic risk to birds.

• Freshwater Invertebrate Life -Cycle Toxicity Test (850.1300) : Non dose-response mortalities were observed in the three lowest trea tment levels for the submitted freshwater daphnid study. Therefore, the resulting toxicity values could not be used quantitatively to assess chronic risk to aquatic invertebrates. Despite the lack of valid data, chronic risk to fr eshwater invertebrates is not expected to exceed the Agency’s LOC. Environmental concentrations of am inocyclopyrachlor in surface waters from applications at the proposed maximum rates ar e expected to be in the parts per billion (ppb) range; whereas all aquatic toxicity studies were conducted at concentrations in the parts per million (ppm) range. Based on the resu lts of chronic studies in freshwater fish, where the NOAEC is 11 ppm, EPA also expects the freshwater inverte brate NOAEC to be in the ppm range, well above the exp ected environmental concentrations. Therefore, submission of a repeat-study is expected to be confirmatory and will better characterize chronic risk to freshwater invertebrates.



### 2.2. Label Requirements

2.2.1. Environmental Hazards

Based on potential leaching and runoff that may result from the persistence and mobility of aminocyclopyrachlor, the following surface and gr ound water advisories must be placed on all aminocyclopyrachlor end-use product labels.

Surface Water Advisory

Products Primarily Intended for Commercial Use on Non-Crop Areas, Sod Farms, and Turf/Lawns “This Product may impact surface water quality due to spray drift and runoff of rain water. This is especially true for poorly draining soils and so ils with shallow ground water. This product is classified as having high potenti al for reaching surface water via runoff for several months after application. A level, well-maintained vegetative bu ffer strip between areas to which this product is applied and surface water features such as ponds, streams, and springs will reduce the potential loading of aminocyclopyrachlor from runoff water and sediment. Runoff of this product will be reduced by avoidi ng applications when rainfall is forecasted to occur within 48

- 18 -hours. See manual at the following Internet address: http://www.wsi.nrcs.usda.gov/pr oducts/W2Q/pest/core4.html”

Products Primarily Intended for Consumer Use on Residential Lawns “This Product may impact surface water quality due to spray drift and runoff of rain water. This is especially true for poorly draining soils and so ils with shallow ground water. This product is classified as having high potential for reaching surface water via runoff for several months after application. Avoid accidental or intentional application of this product to ditches, swales, drainage ways or impervious surfaces such as dr iveways. Runoff of this product to surface water will be reduced by avoiding applications when rainfa ll is forecasted to oc cur within 48 hours.”

Ground Water Advisory

All End-Use Products “This chemical has properties and characteristic s associated with chemicals detected in ground water. This chemical may leach into ground wate r if used in areas where soils are permeable, particularly where the water table is shallow.”

2.2.2. Plant Residue

Although no incidents have been reported for aminocyclopyrachlor, a pyrimidine carboxylic acid, because it is a new chemical; several incide nts have been reported for a similar class of chemicals, the pyridine carboxylic acids, whic h includes herbicides such as aminopyralid, clopyralid, and picloram. Incidents were reporte d where treated plant residues or manure from

animals which were fed treated residues were us ed in compost, which caused desirable crop or lawn damage. Some states as well as the Un ited Kingdom were prompted to take regulatory

action due to these incidents. Since aminocyclopyrachlor also shar es the persistent and systemic nature in soil and the high seedling emergence toxicity with these similar chemicals, similar incidents could occur following application of am inocyclopyrachlor. Therefore, the Agency is requiring that the following language be plac ed on all aminocyclopyrachlor end-use product

labels:

Plant Residue Restrictions

Products Primarily Intended for Commercial Use on Non-Crop Areas “Do not use plant material treated with this product for mulch or compost.”

Products Primarily Intended for Commerc ial Use on Sod Farms and Turf/Lawns “Do not send grass clippings from treated areas to a composting facility or use grass clippings from treated areas for mulch or compost. Applicators must give notice to property owner/property manager/residents to not use grass clippings from treated turf for mulch or compost.”

Products Primarily Intended for Consumer Use on Residential Lawns

- 19 -“Do not use grass clippings from treated areas for mulch or compost. Grass clippings must either be left on the treated lawn or if allowed by local yard waste regulati ons, disposed of in the

trash”

2.2.3. Livestock

Aminocyclopyrachlor can be applied in uncultivat ed agricultural areas and other areas with potential exposure to livestock via feeding or grazing. Since aminocyc lopyrachlor is proposed

for non-food use and no tolerances have been established on livestock commodities, the following restriction is required on all end-use labels to protec t feeding exposure to livestock.

Livestock Restriction

Products for Use on Non-Crop Areas “Do not graze or feed forage, hay, or straw from treated areas to livestock.”

2.2.4. Spray Drift

As expected for an herbicide, aminocyclopyrachlor presents potential risk to terrestrial plants, particularly through spray drift (see Section 1.3.3.2.4) . In order to mitigate risk to non-target plants and keep the pesticide on the intended tr eatment area, the following spray drift language must be placed on all aminocycl opyrachlor end-use product labels:

Spray Drift Management The phrase “(>150 – 200 microns)” must be removed fr om the current spray drift management

statement so that it reads “The most effective way to reduce spra y drift potential is to apply large droplets. The best drift management strategy is to apply the largest droplets that provide sufficient coverage and control.”

Products Primarily Intended for Commercial Use on Non-Crop Areas

Aerial Application Restriction “When applying by air, maintain a 50-foot bu ffer around non-target aquatic areas and between the point of direct application and the closest downwind edge of non-target terrestrial areas. Apply only using nozzles which will deliver coarse or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. Do not release sp ray at a height greater than 10 feet above the ground or crop canopy unless a greater height is required for aircraft safety. Do not apply when wind speed is greater than 10 mph. Do not apply during a temp erature inversion.”

Ground Application Restriction “When applying by ground, maintain a 50-foot buffer around non-target aquatic areas and between the point of direct appl ication and the closest downwind e dge of non-target terrestrial areas. Apply only using nozzles which will de liver coarse or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. Do not apply with a nozzle height greater than 4 feet above the ground or crop canopy. Do not appl y when wind speed is greater than 10 mph. Do not apply during a temperature inversion.”

- 20 -- 21 - Products Primarily Intended for Commerc ial Use on Sod Farms and Turf/Lawns (Ground Applications Only)

Application Restriction “Maintain a 25-foot buffer around non-target aq uatic areas and between the point of direct application and the closest downwind edge of non-target terr estrial areas. Apply only using nozzles which will deliver coarse or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. Do not apply with a nozzle height greater than 4 feet above the ground or crop canopy. Do not apply when wind speed is greater than 10 mph. Do not apply during a temperature inversion.”

2.2.5. Restricted-Entry Interval (REI)

The REI must be changed to 12 hours from the proposed REI of 4 hours. The minimum standard REI for agricultural pesticides is 12 hours. EPA allows a reduced REI of 4 hours for certain minimum-risk pesticides that meet low-toxicity standards and that have not been reported to cause illness or injury due to post-application exposure. Si nce aminocyclopyrachlor is a new pesticide with no history of actua l use, incident information (illn ess or injury reports) is not available for this chemical. Therefore, EPA believes the minimum standard REI of 12 hours is appropriate for ami nocyclopyrachlor.



### 2.3. Proposed Registration Decision

In accordance with FIFRA Section 3(c)(7)(C), the Agency believes that the conditional registration of aminocyclopyrachlor will not cause any unreasonable adverse effects to human

health or to the environment and that the use of the pesticide is in the public’s interest; and is therefore proposing to grant the conditional registration.