# Registration of the New Active Ingredient Aminocyclopyrachlor for Use on Non-Crop Areas, Sod Farms, Turf, and Residential Lawns

August 24, 2010

U.S. Environmental Protection Agency Office of Pesticide Programs 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) .........................................................................5

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

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

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

1.2.1.1. Degradate of Concern .................................................................................................................................. 7
1.2.2. Toxicological End Points and Doses .....................................................................................................7

1.2.2.1. Acute Dietary ............................................................................................................................................... 7

1.2.2.2. Chronic Dietary ............................................................................................................................................ 8

1.2.2.3. Short- and Intermediate-Term Incidental Oral and Inhalation ..................................................................... 8

1.2.2.4. Short- and Intermediate-Term Dermal ......................................................................................................... 8

1.2.2.5. Cancer .......................................................................................................................................................... 8
1.2.3. Consideration of Toxicity to Children ...................................................................................................9

1.2.4. Dietary Risk

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

1.2.5. Residential Risk

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

1.2.5.1. Residential Handler Risk ........................................................................................................................... 10

1.2.5.2. Residential Post -Application Risk ............................................................................................................. 10
1.2.6. Aggregate Risk

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

1.2.7. Occupational Risk

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

1.2.7.1. Occupational Handler Risk ........................................................................................................................ 11

1.2.7.2. Occupational Post-Application Risk .......................................................................................................... 12 1.3. E NVIRONMENTAL R ISK ................................................................................................ 13

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

1.3.1.1. Degradates of Concern

............................................................................................................................... 13
1.3.2. Environmental Fate ..............................................................................................................................1 3

1.3.3. Ecological Risk

............................................................................................................................... .....14

1.3.3.1. Aquatic Risk

............................................................................................................................... ............... 14

1.3.3.1.1. Fish Risk

............................................................................................................................... ................ 14

1.3.3.1.2. Aquatic Invertebrate Risk ..................................................................................................................... 15

1.3.3.1.3. Aquatic Plant Risk

............................................................................................................................... . 15

1.3.3.2. Terrestrial Risk

............................................................................................................................... ........... 15

1.3.3.2.1. Avian Risk

............................................................................................................................... ............. 15

1.3.3.2.2. Mammalian Risk

............................................................................................................................... .... 16

1.3.3.2.3. Terrestrial Invertebrate Risk ................................................................................................................. 16

1.3.3.2.4. Terrestrial Plant Risk ............................................................................................................................ 16 1.4. P UBLIC I NTEREST ......................................................................................................... 16

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

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

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

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

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

2.2.1.1. Surface Water Advisory ............................................................................................................................. 19

2.2.1.2. Ground Water Advisory ............................................................................................................................. 19
2.2.2. Plant Residue

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

2.2.3. Livestock

............................................................................................................................... ..............21

2.2.4. Spray Drift

............................................................................................................................... ............21

2.2.5. Restricted-Entry Interval (REI) ............................................................................................................23
2.3. R EGISTRATION D ECISION ............................................................................................ 23

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## Registration of the New Active In gredient Aminocyclopyrachlor for Use on Non-Crop Areas, Sod Farm s, Turf, and Residential Lawns

1. REGULATORY RATIONALE

The Agency is granting conditional regi stration of the new active ingredient aminocyclopyrachlor, formulated as 2 technical products, 3 manufacturi ng-use products, and 15 end-use products. It is a se lective herbicide providing pre- and post-emergent control of broadleaf weeds, woody species, vines, and gr asses in non-crop areas [private, public, and military lands: uncultivated non-agricultural areas (such as airports, highway, railroad and utility rights-of-way, sewage disposal areas), uncul tivated 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 being re gistered: the parent aci d (aminocyclopyrachlor), the methyl ester (aminocyclopyrachlor-methyl), and the potassium sa lt (aminocyclopyrachlor potassium salt). The parent acid, aminocyclopyr achlor, 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 either 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). Maximu m annual application rates range from 0.05 – 0.324 lb acid equivalent (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.

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

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 No.: 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-ami no-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 No.: 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

- 5 -1.1.3. Chemical Name: Aminocyclopyrachlor potassium salt
potassi um 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 (pyrimidine carboxylic acid) Registrant: E.I. du Pont de Nemours and Co mpany (EPA Company No.: 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 aminoc yclopyrachlor is adequate for risk assessment for the new use patterns. Aminocyclopyrachlor has low acute toxi city by oral, dermal, a nd inhalation routes of exposure, and does not cause skin sensitization or irritation. However, it can cause mild eye irritation. Aminocyclopyrachlor and aminocyclopyrachlor-methyl have low subchronic toxicity

via the oral route. The most se nsitive species is the rat, with decreased body weight at the limit dose in subchronic dietary studies as the most sensitive endpoint of toxicity. The major effect observed across species for aminocyclopyrachlor was decreased body weight at the limit dose. No toxicity was observed in s ubchronic dietary studies in dogs at the highest dose of aminocyclopyrachlor tested, which wa s half the limit dose, but still higher than the dose at which

no adverse effects occurred in th e rat. No target organ of t oxicity was identified. No sex differences in toxicity were observed for eith er aminocyclopyrachlor or aminocyclopyrachlormethyl.

- 6 -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.

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 new us e pattern, the dietary ex posure 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

- 7 -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 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 based on the new 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.

- 8 -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 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 new food uses for aminocycl opyrachlor, 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

- 9 -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.

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

- 10 -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

• 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 requ ired for the new non-food use patterns because Food Quality Protection Act (FQPA) considerati ons do not apply. However, the potential for significant aggregate exposures to aminocyclopyrachlor from dietary (drinking water) and residential uses relative to non-aggregate expos ures was considered. The highest estimated residential exposure (0.000048 mg/kg/day via in halation during mixing, loading, and applying a granular formulation with a belly grinder) was combined with the highest estimated dietary exposure (0.002778 mg/kg/day for all infants < 1 year old). This combined value of 0.003 mg/kg/day was over 1000- fold lower than the po int of departure of 3.5 mg/kg/day, based on the most conservative LOC for MOE (350 mg/kg/day w ith MOE =100). This estimate indicates that aggregate exposures to aminocyc lopyrachlor will not result in significantly increased risk relative to non-aggr egate 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.

- 11 -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

• 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.

- 12 -

### 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.

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.

- 13 -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.

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 the new 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 environmental concentration (EEC) values resulted from the new 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 applicati ons, which resulted in lower EECs. EECs were compared to toxicity endpoints 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.

- 14 -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; 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 maximum rates are expected to be in the part s per billion (ppb) range ; whereas all aquatic toxicity studies were conducted at concentrations in the parts per million (ppm) range. Based on

the results of chronic studies in freshwater 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).

- 15 -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.

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

- 16 -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.



### 2. REGULATORY DECISION

The Agency is granting conditional regi stration of the new 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 Pr oducts; Registration A pplications” announcing receipt of applications to register pesticide products c ontaining the new active ingredient, aminocyclopyrachlor, by E.I. du Pont de Ne mours and Company. There were no comments received in response to the notice of receipt.

On June 17, 2010, the Agency posted the proposed decision document for aminocyclopyrachlor entitled “Proposed Registration of Aminocyclopy rachlor on Non-Crop Areas, Sod Farms, Turf, and Residential Lawns”, the associated risk asse ssments, and the proposed labels in the docket EPA-HQ-OPP-2009-0789. The registrant provided a response to the Agency on July 16, 2010 entitled “DuPont Response to the EPA’s “Proposed Registration of Aminocyclopyrachlor on Non-Crop Areas, Sod Farms, Turf, and Residential Lawns”. No other comments were received.



### 2.1. Data Requirements

The Agency has determined that additional data ar e required in order to better characterize risk. The studies identified below are required 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 new uses:

- 17 -• A repeated-dose study in a sensitive species is required to address the hazard of subchronic/chronic exposure to the environmental 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 departure (POD) used in the chronic exposure assessment for drinking water. Even with the additional UF and the conservative assumptions of the drinking water m odels 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

The ecological risk assessment concluded that th e following studies are re quired in support of the

new uses:

• Avian Reproduction Toxicity Test (850.2300) : Data are required for both an upland game and waterfowl species for the new use patterns. The submitted studies were invali d due to improper husbandry practices that may have caused incidental mortalities in qua ils and reduced egg production in mallards. Despite the improper husbandry conditions, th ere was no evidence in either study of adverse treatment-related effects, including overt toxicity, mortality, effects on feed consumption and body weight, macroscopic findi ngs, or reproductive effects. Therefore, submission of a repeat-study performed under proper husbandry conditions is expected to be confirmatory and will better char acterize chronic risk to birds.

• Freshwater Invertebrate Life-C ycle 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 fres hwater invertebrates is not expe cted to exceed the Agency’s

LOC. Environmental concentr ations of aminocyclopyrachlor in surface waters from applications at the maximum rates are expected to be in the parts per billion (ppb) range; whereas all aquatic toxicity studies were c onducted at concentrati ons in the parts per million (ppm) range. Based on the results of chronic studies in freshwater fish, where the NOAEC is 11 ppm, EPA also expects the fres hwater invertebrate NOAEC to be in the ppm range, well above the expected envir onmental concentrations. Therefore, submission of a repeat-study is expected to be confirmatory and w ill better characterize

chronic risk to fres hwater 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, surface and ground water a dvisories must be placed on the following aminocyclopyrachlor end-use product labels.

- 18 -2.2.1.1. Surface Water Advisory

The surface water advisory was revised from the language stated in the proposed decision document by removing the phrase “spray drift and” and the reference to the USDA manual so

that it is consistent with the EPA’s standardized language. Also, the proposed surface water advisory for products primarily intended for consumer use on residential lawns has been replaced with the environmental hazard statem ents recommended in the Pesticide Registration (PR) Notice 2008-1 for outdoor residential use produc ts. These statements present instructions similar to those of the commercial-use surfa ce water advisory, but in terms suitable for

consumers.

Products Primarily Intended for Commercial Use on Non-Crop Areas, Sod Farms, and

Turf/Lawns

“This Product may impact surface water quality due to runoff of rain water. This is especially true for poorly draining soils and soils with shal low ground water. This pr oduct is classified as having high potential for reaching surface water via runoff for severa l months after application. A level, well-maintained vegetative buffer strip between areas to which this product is applied and surface water features such as ponds, stream s, and springs will reduce the potential loading of aminocyclopyrachlor from runof f water and sediment. Runoff of this product will be reduced by avoiding applications when rainfall is forecasted to occur within 48 hours.”

Products Primarily Intended for Consumer Use on Residential Lawns (Broadcast Granular Applications)

“To protect the environment, do not allow pesticide to enter or run off into storm drains, drainage ditches, gutters, or surface waters. Applying th is product in calm weather when rain is not predicted for the next 24 hours will help to ensure that wind or rain does not blow or wash pesticide off the treatment areas. Sweeping a ny product that lands on a driveway, sidewalk, or

street back onto the treated area of the lawn or garden will help to prevent runoff to water bodies or drainage systems.”

2.2.1.2. Ground Water Advisory

The label requirement for the ground water advis ory was revised so that it is required for products primarily intended for commercial us e instead of all end-use products. The ground water advisory for products prim arily intended for consumer use on residential lawns has been replaced with the environmental hazard statements in the PR Notice 2008-1.

Products Primarily Intended for Commercial Use on Non-Crop Areas, Sod Farms, and

Turf/Lawns

“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 wa ter table is shallow.”

- 19 -Products Primarily Intended for Consumer Use on Residential Lawns (Broadcast Granular Applications)

“To protect the environment, do not allow pesticide to enter or run off into storm drains, drainage ditches, gutters, or surface waters. Applying th is product in calm weather when rain is not predicted for the next 24 hours will help to ensure that wind or rain does not blow or wash pesticide off the treatment areas. Sweeping a ny product that lands on a driveway, sidewalk, or

street back onto the treated area of the lawn or garden will help to prevent runoff to water bodies or drainage systems.”

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.

The restriction for products prim arily intended for commercial use on sod farms and turf/lawns was revised for clarity a nd to be more protective.

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 use grass clippings from treated areas fo r mulch or compost, or allow for collection to composting facilities. Grass clippings must either be left on the treated area, or if allowed by local yard waste regulations, disposed of in the trash. Applicators must give verbal or written notice to property owner/property manager/resident s to not use grass clip ping from treated turf for mulch or compost.”

Products Primarily Intended for Consumer Use on Residential Lawns

“Do not use grass clippings from treated areas for mulch or co mpost. Grass clippings must

either be left on the treated lawn or if allowed by local yard waste regulations, disposed of in the

trash.”

- 20 -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 being registered for non-food use and no tolerances have been established on livestock commodities, the following restriction is required on all app licable end-use labels to protect feeding exposure

to livestock.

Livestock Restriction

Products Primarily Intended for Commercial Use on Non-Crop Areas

“Do not graze or feed forage, hay, or st raw 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 trea tment area, spray drift language must be placed on aminocyclopyrachlor end-use product labels that are applied as liquids.

Spray Drift Management The phrase “(>150 – 200 microns)” must be rem oved from the current spray drift management

statement so that it reads “The mo st effective way to reduce spray drift potential is to apply large droplets. The best drift mana gement strategy is to apply th e largest droplets that provide sufficient coverage and control.”

Products Primarily Intended for Commercial Use on Non-Crop Areas

The application restrictions for products pr imarily intended for commercial use on non-crop areas were revised from those specified in th e proposed decision document by removing the buffer restrictions and including additional restrict ions to further mitigate spray drift. The aminocyclopyrachlor products labeled for “non-crop areas” are intended for vegetative management (VM) use in areas such as utility ri ghts-of-way, roadsides, and railroads. In such situations, the treatment area is typically na rrow and linear, requiring si ngle-swath applications. By contrast, agricultural applications cover a wi der area with multiple swaths. While buffers may be practical for agricultura l applications, th ey would overly restrict or, in some cases, preclude use in many non-crop areas. In additi on, the narrow, linear treatment area in VM applications may reduce the potential for runoff and drift compared to agricultural applications, thereby obviating the ne ed for buffers.

As described in the registrant’s response to the proposed decision, herb icides are important tools in VM/IVM programs for controlling inva sive/noxious species and ensuring human safety. The ability to apply herbicides up to the edge of target areas will avoid or minimize the need for mechanical mowing, which is an inef fective method of eradicating inva sive/noxious weeds. Also, systemic herbicides such as aminocyclopyrach lor will provide long-term control of weeds and

- 21 -reduce proliferation, as compared to herbicides used for chemical mowing such as glyphosate. Furthermore, the ability to use sy stemic herbicides up to the edge of target areas will reduce the need for applicators to make spot treatments us ing backpack sprayers. Complete control of weeds in rights-of-way also ensures public and wor ker safety by providing a clear line-of-sight, reducing fire and electrical hazards, and reducing obstructions. EPA notes that Canada’s Pest Management Regulatory Authority (PMRA) rou tinely exempts VM herbicides from buffer requirements provided that spray drift concerns can be addressed in other ways. With advances in application technology, spray drift to non-targ et areas can be reduced without the need for buffers through the use of specia lized spray equipment, nozzl es, and drift control agents. Therefore, to address and mitigate spray drift in the absence of buffer requirements, additional restrictions will be placed on VM labels to en sure that applications will be protective of nontarget areas.

Use Restrictions

“Do not make applications when circumstan ces favor movement from treatment site.”

“Do not apply or otherwise permit this product or sprays containing this product to come into contact with any non-target crop or desirable broadleaf plants.”

“Do not contaminate water intended for irrigation. To avoid injury to cr ops and other desirable plants, do not treat or allow spray drift or r unoff to fall onto banks or bottoms of irrigation ditches, either dry or co ntaining water, or other channels that carry water that may be used for irrigation purposes. Do not apply to snow covered or frozen ground.”

Aerial Application Restrictions

“When applying by air, apply only using nozzles which will deliver coarse or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. Do not release spray at a height greater than 10 feet a bove the ground or canopy unless a greate r height is required for aircraft safety. Do not apply when wind speed is greater than 10 mph. Do not apply during a temperature inversion.”

“For aerial applications near su sceptible crops or other desira ble plants, use a drift control additive as recommended by the manufacturer, or apply through a Micro-Foil or Thru-Valve boom, or use an equivalent drift control syst em. Thickened sprays prepared by using high viscosity invert systems or other drift control systems may be utilized if drift control is comparable to that obtained with drift control additives or the Thru-Valve boom. If a spray thickening agent is used, follow all recommendati ons and precautions on the product label. Do not use a thickening agent with the Micro-Foil boom or other systems that cannot accommodate thick sprays.”

Ground Application Restrictions

“When applying by ground, apply only using nozzles which will deliver coar se or greater (VMD >350 microns) droplets as defined by ASABE S572 standard. Do not apply with a nozzle height

- 22 -- 23 - greater than 4 feet above the ground or canopy unless necessitated by the application equipment. Apply with the spray boom or nozzle height as lo w as possible. Do not apply when wind speed is greater than 10 mph. Do not a pply during a temperature inversion.”

“For ground applications, keep the spray boom as low as possible; apply 10 gallons or more of

spray per acre; use spray pressures no greater than are required to obtain adequate plant coverage; use large-droplet produc ing nozzle tips; use drift control additi ves; use shieldedsprayers or other drift cont rol systems; and/or spray when wind velocity is low.”

Products Primarily Intended for Commercial Us e on Sod Farms and Non-Residential, NonInstitutional, or Non-Industrial Turf (Golf Courses, Parks, Cemeteries, and Athletic Fields)

The requirement for the ground applic ation restrictions was revised to clarify that it is required for products primarily intended for commercial use on sod farms and turf (non-residential, noninstitutional, non-industrial). The ground application restrictions for commercial use on sod farms and turf were revised by changing the volume mean diameter to “>250 microns” to correspond to the ASABE S572 standard for coarse dr oplets of “250 – 375 microns”. There are no aerial application restrictions since no products are being regist ered for aerial applications to sod farms and turf/lawns.

Ground Application Restrictions

“Maintain a 25-foot buffer around non-target aquatic areas and between the point of direct application and the closest downw ind edge of non-target terrestri al areas. Apply only using nozzles which will deliver coarse or greater (VMD >250 microns) droplets as defined by ASABE S572 standard. Do not apply with a noz zle 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. 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 granting the conditional registration.