3 

### I. INTRODUCTION

This document is the Environmental Prot ection Agency’s (EPA or the Agency) Interim Registration Review Decision for paclobutrazol (case 7002, PC code 125601) and is being issued pursuant to 40 CFR sections 155.56 and 155.58. A regist ration review decision is the Agency's determination whether a pesticide meets, or does not meet, the standard for registration in the Federal Insecticide, Fungicide, and Rodenticid e Act (FIFRA). The Agency may issue, when it determines it to be appropriate, an Interim Registration Review Deci sion before completing a registration review. Among other things, the Interim Registrati on Review Decision may: 1) require new risk mitigation measures; 2) impose interim risk mitigation measures; 3) identify

additional data or other informa tion required to complete the re view; and 4) include schedules for submitting the required data, conducting th e new risk assessment, and completing the registration review. For further information on paclobutrazol, additional documents can be found in EPA’s public docket (EPA-HQ-OPP-2006-0109) at www.regulations.gov

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FIFRA, as amended by the Food Quality Pr otection Act (FQPA) of 1996, mandated the continuous review of existing pest icides. All pesticides distributed or sold in the United States generally must be registered by the EPA based on sc ientific data showing that they will not cause

unreasonable risks to human health or to the environment when used as directed on product labeling. In 2006, the Agency implemented the re gistration review program pursuant to FIFRA section 3(g) and will review each registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard for regi stration. The registration review program is intended to make sure that, as the ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides co ntinue to meet the st atutory standard of no unreasonable adverse effects. Changes in science, public policy, and pestic ide use practices will occur over time. Through the registration review program, the Agency periodically re-evaluates pesticides to make sure that as these changes occur, products in the marketplace can continue to be used safely. Information on this program is provided at www.epa.gov/oppsrrd1/registration_review/

.

The first pesticide product containing paclobutrazol was registered in 1985. Paclobutrazol is a systemic plant growth regulator registered for use to produce dense, compact plants. Paclobutrazol is curre ntly registered for use on or namentals in greenhouses and nurseries. It is also registered for use on turf grass (including in parks, athletic fields, golf courses, and rights-of-ways). It is applied as a tr ee injection, as a soil injection/basal tree drench, and as a seed treatment for cucurbit, tomato, pe pper, cabbage, broccoli, and cauliflower. There are no registered residential us es of paclobutrazol. Paclobut razol was not subject to the reregistration program because products contai ning paclobutrazol were fi rst registered after November 1984. Pursuant to 40 CFR section 155.50, EPA formally initiated registration review for paclobutrazol (case 7002) in March 2007. The following highlights are significant events that have occurred during the registration review of paclobutrazol and can be found in the public docket (EPA-HQ-OPP-2006-0109, accessible at www.regulations.gov ).

 March 28, 2007 – The Paclobutrazol Summary Document was published for a 60-day public comment period. The Summary Document included the Preliminary Work Plan (PWP) and was accompanied by the human heal th scoping document and ecological fate and effects problem formulation. Five public comments were receiv ed during the 60-day4 comment period for the paclobutrazol PWP. Th e public comments receiv ed did not result in changes to the Agency’s work plan for paclobutrazol.

 August 29, 2007 – The Paclobutrazol Final Work Plan (FWP) was published. In the FWP, the Agency responded to the comment s received concerning the PWP, the problem formulation, scoping document and other suppor ting documents in the registration review

docket.

 September 19, 2008 – The Generic Data Call -In Notice (GDCI) for paclobutrazol was issued. The GDCI required the following st udies for the registration review of paclobutrazol:

o Guideline 830.7050—UV/visible absorption

o Guideline 850.1400—Fish early-l ife stage toxicity

o Guideline 850.2300—Avian reproduction test

o Guideline 850.4100—Terrestrial plant toxicity (seedling emergence)

o Guideline 850.4150—Terrestrial plan t toxicity (vegetative vigor)

 September 27, 2013 – The Agency placed in the docket the Registration ReviewEcological Risk Assessment and Eff ects Determination of Paclobutrazol and the Paclobutrazol: Preliminary Hu man Health Risk Assessment for a 60-day public comment period. During that time, three public comments were received from Syngenta, Crop Life America, and an anonymous private citizen. To address uncertainty in the human health risk assessment regarding paclobutrazol’ s neurotoxicity, Syngenta subsequently submitted acute neurotoxicity data to EPA (w ith the understanding that these data were not required under the GDCI for paclobutrazol) . New acute neurotoxic ity data warranted revisions to the Agency’s Paclobutrazol: Preliminary Human Health Risk Assessment

. Syngenta also submitted new data for freshw ater invertebrates, estuarine/marine invertebrates, terrestrial plants, and aquatic vascular and non-vascular plants, which also warranted minor revisions to the Agency’s or iginal ecological risk conclusions.

 February 2, 2015 – The Agency published the Response to Public Comments on the Paclobutrazol Registration Review Ecological Risk Assessment and Paclobutrazol: Response to Registrant Comments from Synge nta on the Preliminary Human Health Risk Assessment (September 11,2013;DP Barcode:D394230).

 August 10, 2015 –The Agency published the Paclobutrazol Proposed Interim Decision

, along with supporting documents, for a 60- day comment period. No comments were submitted to the Agency during this comment period. Supporting documents for the paclobutrazol proposed interim d ecision include the following:

o The addendum to the environmental fa te and ecological risk assessment for paclobutrazol, titled Revised Chronic Mammalian Risk Conclusions for the Paclobutrazol Registration Review Ecological Risk Assessment . The addendum refines the original mammalian risk assessment using a revised chronic rat endpoint.5 o The addendum to the environmental fa te and ecological risk assessment for paclobutrazol, titled Amended Terrestrial Plant Risk Quotients for the Paclobutrazol Registration Review Ecological Risk Assessment . The addendum revises the terrestrial plant RQs to reflect newly submitted seedling emergence

data.

o The Paclobutrazol: Final Human Health Risk Assessment for Registration

Review , which refines the original human health risk assessment based upon submission of neurotoxicity data.

 December 2015 – The Agency is now publishing the Paclobutrazol Interim Registration

Review Decision on www.regulations.gov under docket number EPA-HQ-OPP-2006-

0109.



### II. USE AND USAGE

Paclobutrazol is a systemic plant growth regulator that slows vegetative growth by inhibiting cell elongation. It is registered for use to produce dens e, compact growth in plants. Paclobutrazol is currently registered for use on turf grass (including in parks, athletic fields, gold courses and rights of ways), on ornamentals in gr eenhouses and nurseries, as a tree injection, as a soil injection/basal tree drench and as a seed treatment for cucurbit, tomato, pepper, cabbage, broccoli and cauliflower. There are no regist ered residential uses of paclobutrazol.

The majority of paclobutrazol a pplications are: golf course turf, landscaping settings and nurseries and greenhouses. Pacl obutrazol is used on turf to provide suppression of annual bluegrass (where creeping bentgrass is desired), provide suppression of dollar spot turf disease, and to suppress vertical growt h. Thus, use of paclobutrazol in golf course turf maintenance provides both aesthetic as well as economic benefits ( i.e. , reduced mowing and maintenance costs).

Use of paclobutrazol in the ornamental sect or provides certain benefits as well. Paclobutrazol promotes uniform flowering and imp roves cutting quality and yield, while neither causing a delay in flowering nor re ducing flower size. Paclobutrazo l is also noted to provide a broad-range of control across many species (ema il communication from a technical registrant, June 10, 2015).



### III. SCIENTIFIC ASSESSMENTS

A. Human Health Assessment

The HED scoping document, its supporting documents, and the most updated Agency science policies and risk assessment methodologies were used to prepare a quantitative risk assessment in support of the registration review of paclobutrazol. A preliminary human health risk assessment for registration review was completed in September 2013, entitled,6 Paclobutrazol Preliminary Human Health Risk Assessment for Registration Review . A revised

human health risk assessment was completed in January 2015, entitled Paclobutrazol: Final Human Health Risk Assessment for Registration Review , which incorporated new neurotoxicity data and revised toxicological endpoints. For these and other documents, please see the public docket EPA-HQ-OPP-2006-0109, which can be accessed on http://www.regulations.gov/

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1. Risk Estimates

Dietary Exposure Assessment

Paclobutrazol does not have food uses, ther efore the dietary risk assessment only considered exposure from drinking water. An acute dietary risk assessment (drinking water only) was performed that incorporated potential drinking water residues (see Revised Tier I Drinking Water Assessment for the Registration R eview of Paclobutrazol on Turf (commercial, ornamental and golf courses), Ornamental and Shade Trees, and Seed Treatment of Tomato, Pepper, and Cucurbit , dated March 13, 2014). The resultin g acute and chronic drinking water risk estimates were below the Agency’s level of concern (LOC) where estimated exposure for the general population was 17% of the acute population adjusted dose (aPAD) and was 54% of the aPAD for infants <1 year old, (the most highly exposed population subgroup). Chronic dietary exposure was estimated to be 12% of the chronic population adjusted dose (cPAD) for the general population and 31% of the cPAD for in fants <1 year old, (the most highly exposed population subgroup).

Residential Exposure Assessment

Paclobutrazol is not registered for homeowner use in residential settings, therefore, a

residential handler assessment was not conducted. However, a residential post-application assessment was performed because paclobutrazol app lication to turf, in se ttings such as parks and golf courses, is expected to result in residential post-app lication exposure (via dermal and incidental oral routes of exposur e). Residential post-application ri sk estimates did not exceed the Agency’s LOC (where the LOC for margin of exposure (MOE) is 100). Dermal MOEs range from 170 to 16,000, and oral non-dietary MOEs (fr om hand-to-mouth activity on treated turf) range from 210 to 1,400,000.

The Agency considered indirect residentia l exposure to children and adults who may have contact with paclobutrazol residues assumed to have been deposited via spray drift. The Agency determined that the residential post-appl ication exposure risk a ssessment was protective for exposure from spray drift and therefore, it wa s determined that a spra y drift residential risk

assessment was not needed. Aggregate Exposure Assessment

Aggregate risk estimates ta ke into account both dietary (food and drinking water) and residential sources of exposure. Since pacl obutrazol does not have f ood uses, the aggregate assessment for paclobutrazol included only drinki ng water exposure estimates plus residential post-application exposure estimates.

 Acute aggregate risk is equivalent to drinking water exposure only and therefore

is not of concern.7  Short-term aggregate risk is equivalent to drinking water exposure plus short-term residential exposure, and is not of con cern (MOE=780 for children 1-2 years old, MOE=140 for adults, where the LOC for MOE=100).

 Intermediate term aggregate risk was not estimated because residential postapplication exposure is expected to be short-term in duration only.

 Chronic aggregate risk is equivalent to chronic dietary risk because residential post-application is expected to be short-term in durati on. Chronic aggregate risk

therefore is not of concern.

Cumulative Effects

Section 408(b)(2)(D)(v) of the Federal F ood, Drug, and Cosmetic Act (FFDCA) requires the Agency to consider the cumulative effects of exposure to substanc es that have a common mechanism of toxicity. These considerations include the possible cumulative effects of such

residues on infants and children.

EPA has not made a common mechanism of toxicity finding for paclobutrazol and any other substances, and paclobutr azol does not appear to produce a toxic metabolite produced by other substances. Therefore, EPA has not assu med that paclobutrazol has a common mechanism of toxicity with other substances and a cumu lative effects assessment was not performed.

Occupational Exposure Assessment

The occupational assessment estimates risk to handlers (those who mix, load and apply a pesticide) and to workers (those who re-enter a treated area to pe rform tasks) in an occupational setting via the dermal and inha lation routes of exposure.

Occupational handler exposure was assesse d for use of pacl obutrazol on turf, ornamentals, and as tree treatments. Short and in termediate term risk estimates for occupational handlers for nearly all scenario s were not of concern to the Agency (MOEs range from 29 to 19,000,000, with the LOC for MOE=100). The one excep tion is mixing/loading/applying liquids via backpack sprayer for basal tree drench trea tments where the MOE=29 with baseline personal protective equipment (PPE), and the MOE= 58 with full PPE. Additional information surrounding these risk estimates can be found below in section 2. Human Health Risk

Characterization.

The Agency also assessed occupational risks associated with paclobutrazol use as a seed treatment. The Agency assessed risks associated with seed treatment activ ities, as well as risks associated with seed planting activities. Risk es timates for all occupational scenarios were not of concern to the Agency, where MOEs range from 16,000 to 13,000,000.

Occupational post-applic ation inhalation exposure (via vo latilization of paclobutrazol and resuspension of dusts/particulates) was considere d. The Agency expected that handler exposures (associated with ornamental, tree, and turf uses) would be highe r than those that would result from post-application activities. Therefore, since handler exposur e can be considered protective of post-application inhalation e xposures, and handler risks ar e not of concern, the Agency8 determined that a quantitativ e occupational post-a pplication exposure assessment was not

needed.

Occupational post-application dermal exposure (from activities such as golf course maintenance, hand-harvesting, pruning, weeding, a nd grafting) was assessed. Based on currently registered uses, short-term (1 to 30 days) and in termediate-term (30 days to 6 months) exposures are expected. Occupational post- application dermal risk estimates were not of concern where MOEs range from 110 to 2,800.

2. Human Health Risk Characterization

The human health risk assessment identifie d potential risks for occupational handlers mixing/loading/applying liquid p aclobutrazol via backpack sprayer for basal tree drench treatments. The Agency notes th at paclobutrazol labels do not sp ecify the application method for this use and so this scenario was initially assesse d assuming application with a backpack sprayer. The Agency estimated an MOE = 29 at baseline ( i.e. , assuming no PPE) and an MOE = 58 with PPE ( i.e. , assuming gloves and double layer clothing). However, based upon information from the technical registrants, the Agen cy learned that backpack spraye rs are not used to make basal tree drench applications because backpack sprayers do not efficiently deliver the volume of material usually needed for basal tree drench app lications. Rather, basal tree drench applications are typically made with either a hand-held hos e connected to a truck- mounted spray tank (email communication from a technical registrant, Januar y 23, 2015) or with a hydr aulic sprayer with a hand held application nozzle (email communicati on from a technical registrant, January 28, 2015). Further, in situations where the target tree(s) are inaccessible wi th a truck-mounted or hydraulic sprayer, basal tree drench applicatio ns are made with a bucket or a 2.5 gallon jug (email communication from a technical registrant, January 30, 2015).

The Agency determined that application vi a truck-mounted, or hydr aulic sprayer can be represented by another occupational handler scenario already assessed by the Agency: “mixing/loading/applying liquids with a mechan ically pressurized hand wand” for drench tree treatments (p. 33 of the human health risk as sessment). Similarly, the application via jug application can be represented by the “mixing/loading liquids for the tree soil injection” exposure scenario already assessed by the Agency (p. 31 of the human health risk assessment). When these existing scenarios are adjusted to represent paclobutrazol basal tree drench application ( i.e. , 0.31 lbs. active ingredient per tree for 50 trees in a day), estimated MOEs are not of concern, where the MOE for the hand wa nd scenario is 2,100, and the MOE for the jug scenario is 1,100 (see Table 1 below).9 Table 1. Estimated dermal and inhalation exposu re for the basal tree drench use of paclobutrazol, from jug application and applicat ion via hydraulic sprayer/truck-mounted spray

tank.

Activity Dermal dose (mg/day) Dermal

MOE Inhalation dose (mg/day) Inhalation

MOE Total

MOE

Jug application 0.00924 1100 0.0000491 200,000 1,100

Application via hydraulic sprayer or truck-mounted spray

tank 0.00447 2,200 0.000239 42,000 2,100

The current paclobutrazol labels do not spec ify the application method or the equipment

to be used for basal tree drench. To ensure th e most realistic and safe application methods are being used in the field, the Agency is requiri ng revised label language to be placed on each applicable label with directions for use as a basal tree drench. This language can be found in

Section IV of this document.

3. Human Incidents

For this registration review, an incident sear ch was initially conducte d in February 2007.

There were two incidents identified in the Main and Aggregate Incident Data System (IDS) from

1999 to 2007. There were no incide nts identified in the Poison C ontrol Center database from

1993 to 2005. There were no incidents in the Na tional Institute of Occupational Safety and Health Sentinel Event Notification System fo r Occupational Risks (NIOSH SENSOR) database from 1998 to 2003. An updated incident sear ch was conducted in January 2015. No new incidents were found in IDS from January 2010 to January 2015; no new incidents were found in

NIOSH SENSOR from 1998 to 2011. For addi tional details, please refer to the Paclobutrazol:

Final Human Health Risk Asse ssment for Registration Review in docket EPA-HQ-OPP-2006- 0109, which can be accessed at www.regulations.gov

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4. Food Tolerances

Paclobutrazol does not have registered food us es and therefore no food tolerances have

been established.

5. Human Health Data Needs

No human health data needs for paclobutrazo l were identified by the Agency during the

human health risk assessme nt for registration review.10 B. Environmental Assessment

The paclobutrazol problem formulation docum ent, ecological risk assessment and supporting documents, as well as the most update d Agency science policie s and risk assessment methodologies were used to prepare a quantitativ e ecological risk assessment in support of the registration review of pa clobutrazol. For detailed discussions of all aspects of the environmental risk assessment, see the Registration Review—Ecologica l Risk Assessment and Effects Determination of Paclobutrazol , the Response to Public Comments on the Paclobutrazol Registration Review Ecological Risk Assessment , the Revised Chronic Mammalian Risk Conclusions for the Paclobutrazol Registra tion Review Ecological Risk Assessment , and the Amended Terrestrial Plant Risk Quotients for the Paclobutrazol Registra tion Review Ecological

Risk Assessment in the public docket (EPA-HQ-O PP-2006-0109) which can be accessed on http://www.regulations.gov/

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For non-listed species, no risks were identifi ed for non-vascular plants and terrestrial invertebrates. However, potenti al risks were identified for bird s, reptiles, terrestrial-phase amphibians, mammals, terrestrial and aquatic plants , freshwater fish and invertebrates, aquaticphase amphibians, and estuarine/ma rine fish and invertebrates.

The Agency also completed a screening-level endangered and threatened (listed) species assessment for paclobutrazol and identified potentia l risks to several taxa (aquatic vascular plants, terrestrial plants, freshwater fish/am phibians, estuarine/marine fish, freshwater invertebrates, estuarine/marine invertebrates, mammals, and birds). Birds were used as a surrogate for terrestrial-phase amphibians and rep tiles. The Agency is working with its federal counterparts and other stakeholders to implement an interim approach for a ssessing potential risk to listed species and their designa ted critical habitats. Once the scientific methods necessary to complete risk assessments for listed species and their designated critical habitats are finalized, the Agency will complete an endangered species assessment for paclobutrazol. As such, risks to listed species will not be characterized herein.

1. Environmental Fate and Exposure

Paclobutrazol is not very soluble in water, is non-volatile under field conditions, and has the potential to bioaccumulate in aq uatic organisms. It is stable to hydrolysis and photolysis and appears to be persistent in acidic soils, but not so in neutral or basic soils. Paclobutrazol is considered persistent and mobile, with half-lives up to 973 days in terrest rial field dissipation

studies. Available fate data in dicate two major environmental degradates of paclobutrazol: the ketone analog of paclobutrazol (CGA149907) and 1H-1,2,4-triazol-3-ol (NOA457654).

2. Risk Conclusions

The agency assessed ecological risk from the uses of paclobutrazol, including paclobutrazol use on:

 Turf

 Seed treatment for agricultural crops

 Trees, trunk injection

 Trees, soil injection11  Trees, basal drench

 Potted ornamentals, spray

 Potted ornamentals, drench

The Agency has made a “no effect” determina tion for aquatic non-vasc ular plants, due to the absence of any currently listed non-vascular a quatic plants.

Direct Risk to Terrestrial Organisms

Birds, Reptiles, and Terr estrial-Phase Amphibians

Acute risk quotients (RQs) were not calculated for birds, (used as a surrogate for reptiles and terrestrial amphibians) because all toxicity data were non-definitive ( i.e. , no definitive toxic effect was identified in the study). When non-defi nitive toxicity values were directly compared to estimated environmental concentrations (EECs) , it was determined that the potential for acute risk to non-listed birds, reptil es, and land-phased amphibians was lo w for all registered uses of paclobutrazol. Chronic RQs for birds only sli ghtly exceeded the Agency’s LOC for the soil injection/drench use, where the chronic RQ s range from 1.1 – 2.3 (chronic LOC=1).

Mammals

For mammals, acute and chronic dosed-based RQs and chronic dietary-based RQs were

calculated for all uses of paclobutrazol.

Acute RQs were below the LOC for non-listed mammals, and only slightly exceeded the LOC for listed mammals. For use on turf, acute RQs range from <LOC–0.11. For use on trees, the acute RQs range from <LOC–0.34. Conseque ntly, acute risk to non-listed mammals are considered unlikely.

Chronic RQs for mammals exceed the LOC for all uses except fo r use of paclobutrazol as a seed treatment. For use on turf, chronic dose-based RQs exceed the Agency’s LOC where RQs range from <LOC–6.41. Chroni c dietary-based RQs were lower and range from <LOC–1.37 (see the document Revised Chronic Mammalian Risk C onclusions for the Paclobutrazol Registration Review Ecological Risk Assessment , dated January 15, 2015, for revised chronic mammalian RQs).

For potted ornamental spray application, chronic RQs only slightly exceeded the LOC ranging from <LOC–1.17.

For paclobutrazol use as a basal tree drenc h, tree soil injection, a nd tree trunk injection, chronic RQs associated with tr unk injection range from <LOC–3.9, an d RQs associated with soil injection/basal tree drench, range from 4–20.

For paclobutrazol use on potted ornament als chronic mammalian RQs range from <LOC–2.1. Thus, there may be chronic risks to ma mmals from all uses of paclobutrazol, except

as a seed treatment.12 Terrestrial Invertebrates

At the initiation of the paclobut razol registration review, data requirements for terrestrial invertebrates (pollinator data) were not identifie d. However, acute or al and contact honeybee data were available for paclobutrazol, but onl y indicated non-definitive endpoints. Based on comparison of the non-definitive values to EECs, the Agency believes that risks to terrestrial invertebrates are not expected from paclobutrazol.

Terrestrial and We tland/Riparian Plants

While RQs associated with the use of paclobut razol as a seed trea tment did not exceed the Agency’s LOC, the remaining uses of pacl obutrazol indicate RQs above the LOC (LOC for

both listed and non-liste d plants is 1).

For use on turf, RQs range from 0. 27–227.78 for both non-listed and listed dry and semi-aquatic plants. LOC exceedance from spray drift was also noted for the turf use, where RQs range from <LOC–13.23.

For use of paclobutrazol on ornamentals as a spray application, RQs range from <LOC– 96.30, whereas RQs for ornamentals as a dren ch application range from 1.48–2,151.68 for both non-listed and listed dry and semi-aquatic plants.

For the use of paclobutrazol on trees as a soil injection/basal tree dr ench, RQs range from 0.15 to 223.40, indicating potential risk concerns for both listed and non-liste d terrestrial plants.

In general, semi-aquatic terrestrial plants had higher RQs compared to dry terrestrial plants. Risks to terrestrial plants are considered likely, but not surprising considering paclobutrazol’s use as a plan t growth regulator (see the Response to Public Comments on the Paclobutrazol Registration Review Ecological Risk Assessment and the Amended Terrestrial Plant Risk Quotients for the Paclobutrazol Re gistration Review Ecol ogical Risk Assessment for revised terrestrial pl ant RQs).

Direct Risk to Aquatic Organisms

The Agency believes that only use on turf and on ornamentals (as a drench/spray) would result in potential exposure to aquatic organisms, and so these were the only paclobutrazol uses modeled for aquatic exposure.

Freshwater Fish and Aquatic-Phase Amphibians

For freshwater fish and freshwater aqua tic-phase amphibians, acute RQs for the

ornamental drench and turf uses did not exceed the Agency’s LOC for either listed or non-listed species. Acute risks to freshwater fish and a quatic-phase amphibians are therefore considered unlikely.13 For the ornamental drench use, chronic fres hwater fish RQs range from <0.1 to 6.8 for ornamental drench. For the turf use, chronic freshwater fish RQs range from 0.43 to 1.4. Both

uses therefore exceeded the chronic LOC of 1.

Estuarine/Marine Fish

Paclobutrazol data were not available for estim ating acute toxicity to estuarine/marine fish. Data from structurally-similar triazoles were used as a surrogate to estimate risk. Based on surrogate data, acute RQs range from <LOC – 0.21 for ornamental drench, which was below the LOC for non-listed species ( 0.5), but slightly exceed the LOC for listed species (0.05). Turf use

scenarios did not result in acute RQs of concern for either listed or non-listed estuarine/marine

fish.

Chronic RQs range from <LOC to 83 for the or namental drench use and range from 5 to 17 for the turf use, exceeding the Agency’s chroni c LOC of 1.

Freshwater Invertebrates

Acute RQs for freshwater mollusks did not exceed the Agency’s LOC for either the

ornamental drench or turf use. For freshwater invertebrates, acute RQs range from <0.01-1.4 for

ornamental drench. For the turf us e, RQs range from 0.09 – 0.28.

Chronic RQs range from <LOC – 1.04 for the or namental drench use, and were below the LOC for the turf use (see the document Response to Public Comments on the Paclobutrazol Registration Review Ecological Risk Assessment , dated October 9, 2014 for revised freshwater invertebrate chronic RQs).

Estuarine/Marine Invertebrates

For estuarine/marine invertebrates, toxicity data for paclobutrazol were available, but RQs could not be calculated because the endpoints were non-definitive. Based upon a comparison of the highest EEC to the most sensitive endpoint for mysid shrimp, the Agency determined that acute risk to estuarine/marine invertebrates is unlikely (see the document Response to Public Comments on the Paclobutra zol Registration Revi ew Ecological Risk

Assessment , dated October 9, 2014 for a revised estuar ine/marine invertebrate acute risk description).

Chronic RQs however, range from <LOC–9.5 fo r the ornamental drench use and range

from <LOC–2.0 for the turf use.

Aquatic Vascular and Non-vascular Plants

For aquatic vascular plants, RQs range from <LOC-202 for the ornamental drench use, and range from 13 to 41 for the turf use (see the document Response to Public Comments on the Paclobutrazol Registration Review Ecological Risk Assessment , dated October 9, 2014 for a revised aquatic plant risk description).14 For aquatic non-vascular plants, RQs were below the Agency’s LOC for both the

ornamental drench use and the turf use.

Table 2. Summary of risks for non-listed species for all taxa across all uses of paclobutrazol.

Taxa Endpoint LOC –

listed/nonlisted Turf

use Treetrunk injection Tree – basal

drench/soil injection Ornamental

spray Ornamental

drench

Birds chronic 1 1.1–2.3

Mammals acute 0.1/0.5 <LOC–

0.11 <LOC-0.34

chronic 1 <LOC–

6.41 <LOC-3.9 4-20 <LOC–1.17 <LOC–2.1

Terrestrial plant – dry 1 <LOC3.57 <LOC–2.01 <LOC–1.24 1.48-19.33

Terrestrial Plant

-- Wetland 1 1.91-

24.96 1.54-20.07 <LOC–8.65 14.81-193.34

Freshwater Fish chronic 1 <LOC–

1.4 <LOC–6.8

Estuarine/marine

Fish acute 0.05/0.5 <LOC–0.21

chronic 1 5-17 <LOC–83

Freshwater

Invertebrates acute 0.05/0.5 0.09–

0.28 <LOC–1.4

chronic 1 <LOC–1.04

Estuarine/marine

Invertebrates chronic 1 <LOC–

2.0 <LOC–9.5

Aquatic Plants 1 13-41 <LOC-202

3. Ecological Incidents

A search was conducted for ecological in cidents for paclobutrazol on September 23, 2011, using the Ecological Incide nt Information System (EIIS), the Aggregate Summary Module of OPP’s Incident Database, and the Avian Inci dent Monitoring System (AIMS). In the EIIS, there was one incident reported for paclobutr azol from 1988 to 2011. The incident involved three dead squirrels in Fl orida and was listed as “unlikely” to have been caused by paclobutrazol.

There were two incidents listed in the Aggregate Summary Modul e: a minor fish and wildlife incident in 2005, and a minor plant incident in 2009. There were no reported incidents in AIMS. For additional details, please refer to Registration Review-Ecol ogical Risk Assessment and Effects Determination of Paclobutrazol , dated March 26, 2013 in docket EPA-HQ-OPP-2006- 0109, which can be accessed at www.regulations.gov

.

4. Ecological Effects Data Needs

The Agency identified several data gaps for paclobutrazol in its ecological risk

assessment. These are:

 Acute risk to estuarine/mari ne fish (guideline 850.1075)

 Chronic risk to estuarine/ma rine fish (guideline 850.1400)

 Chronic risk to estuarine/marine invertebrates (guideline 850.1350)

 Acute oral risk to passeri ne birds (guideline 850.2100)

 Translocation of paclobutrazol in plant parts15  Paclobutrazol uptake rate in tu rf, trees, and ornamentals

5. Endangered Species Assessment

In November 2013, the EPA, along with the Se rvices and the USDA, released a summary of their joint Interim Approaches for assessing risk s to endangered and threatened (listed) species from pesticides. The Interim Approaches 1 were developed jointly by the agencies in response to the National Academy of Sciences’ (NAS) recomm endations and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences between the EPA and the Services. The NAS report 2 outlines recommendations on specific scientific and

technical issues related to th e development of pesticide risk assessments that EPA and the

Services must conduct in conn ection with their obligations under the ESA and FIFRA.

The joint Interim Approaches were released prior to a stakeholder workshop held on November 15, 2013. In addition, the EPA presen ted the joint Interim Approaches at the December 2013 Pesticide Program Dialogue Co mmittee (PPDC) and State-FIFRA Issues Research and Evaluation Group (SFIREG) meetings. The agenci es also held stakeholder workshops - in April and October 2014, and in April 2015 - allowing additional opportunities for stakeholders to comment on the Interim Appro aches. Additional workshops are planned to enhance stakeholder involvement. As part of a phased, iterative process for developing the Interim Approaches, the agencies will also c onsider public comments on the Interim Approaches in connection with the development of upcoming registration review deci sions. The details of the joint Interim Approaches ar e contained in the white paper Interim Approaches for NationalLevel Pesticide Endangered Speci es Act (ESA) Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report 3 , dated November 1, 2013.

Given that the agencies are continuing to de velop and work toward implementation of the Interim Approaches to assess the potential risk s of pesticides to listed species and their designated critical habitat, the ecol ogical risk assessment supporting this Interim Decision for
Paclobutrazol does not contain a complete ESA analysis that includes effects determinations for specific listed species or designate d critical habitat. Although EP A has not yet completed effects determinations for specific species or habita ts, for this interim d ecision, EPA’s evaluation assumed, for all taxa of non-target wildlife and plants that listed species and designated critical habitats may be present in the vicinity of th e application of paclobutrazol. This assessment

allows EPA to focus its future evaluations on the types of species where the potential for effects exists once the scientific methods being develope d by the agencies have been fully vetted. When the Agencies have fully developed a nd implemented the scientific methodology for evaluating risks for listed species and their designated critical habitats, these methods will be

1 Interim Approaches for National-Level Pesticide Endangered Species Ac t (ESA) Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report. Available at http://www2.epa.gov/endangered-species /interim-approaches-pesticide-endang ered-species-act-assessments-basednas-report

2 Assessing Risks to Endangered and Th reatened Species from Pesticides . National Academy of Sciences. 1983.

Available from http://www.nap.edu/catalog.php?record_id=18344

3 Available at http://www.epa.gov/espp/2013/nas.html16 applied to subsequent analyses for paclobutrazol as part of completing the final registration

review decision.

6. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA review s numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute,

subchronic and chronic toxici ty, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or syst emic toxicity. These studies include endpoints which may be susceptible to endocrine influenc e, including effects on endocrine target organ histopathology, organ weights, es trus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard asse ssments, EPA evaluates

acute tests and chronic studies that assess growth, developmen tal and reproductive effects in different taxonomic groups. As part of its mo st recent registration decision for paclobutrazol,

EPA reviewed these data and selected the most sensitive endpoints for re levant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), paclobutrazol is subject to the endocrine screening part of th e Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (including pesticide active and other ingredie nts) may have an effect in hu mans or wildlife similar to an effect produced by a “naturally occurring estr ogen, or other such endocrine effects as the Administrator may designate.” The EDSP em ploys a two-tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact w ith the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal sy stems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Ti er 2 tests are necessary based on the available data. Tier 2 testing is designe d to identify any adverse endocr ine-related effects caused by the substance, and establish a dose-re sponse relationship between the dos e and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which contains 58 pest icide active ingredients and 9 inert ingredients. A second list of chemicals, including paclobutrazol, identified for EDSP screening was published on June 14,

2013 4 and includes some pesticides scheduled fo r registration review and chemicals found in

water

. For further information on the status of the EDSP, the policies and pr ocedures, the lists of chemicals, future lists, the test guidelines and the Tier 1 screening ba ttery, please visit our

website. 5

In the interim, EPA is making no human health or environmental safety findings associated with the EDSP screening of paclobut razol. Before completing this registration review, the Agency will make an EDSP FFDCA section 408(p) determination.

4 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of

chemicals.

5 http://www.epa.gov/endo/17 

### IV. RISK CHARACTERIZATION and INTERIM REGISTRATION

REVIEW DECISION

A. Ecological Risk Characterizati on for Non-Listed Species

EPA has identified potential risks for mammals , birds (also surrogates for reptiles and terrestrial-phase amphibians), terrestrial and aq uatic vascular plants, estuarine/marine and freshwater fish, and estuarine/marine, freshwater invertebrates, and aqua tic-phase amphibians. The Agency uses reasonable worst-case scenarios and conservative assumptions in its analysis to be protective. Environmental exposure and risk is highly dynamic and va riable, that is, it can vary greatly with numerous other factors. As a result, environmental risk can be difficult to represent either as a single number (RQ) or even as a RQ range. To better understand an estimated risk, the Agency can characterize es timates by using alternative assumptions and inputs to demonstrate and explore how or whether the estimates of risk change. Below is a brief discussion of several, not all, of the factors that can affect both the magnitude and/or the frequency of risk that may be associated with th e use of paclobutrazol. Only direct risk to nonlisted species will be addr essed in this section.

Risk from basal tree drench/soi l injection use on targeted trees

Potential risks from the basal tree drench and soil injection uses were identified for mammals and birds, but the highe st RQs were for non-target terre strial plants resulting from runoff after application by basal tree drench.

In order to estimate exposure to non-target mammals, bird s, and plants, the Agency needed to characterize movement of p aclobutrazol from the application site ( i.e. , at the base of the tree) to both the edible portion of the tree as well as to the non-targ et plant. Since the Agency lacked data to characte rize the uptake and movement of paclobutrazol in the terrestrial environment and in plants, it was required to make some assumptions in the ecological risk assessment: first, that 100% of the applied paclobutr azol is taken up by the tree, and second, that 100% of what is taken up by the tree is moved in to the edible portion of the tree and therefore available for consumption by birds or mammals.

With regard to exposure to plants, in the eco logical risk assessment, the Agency made the converse of these assumptions. That is, that 100% of the applied pacl obutrazol was moved from the application site to th e non-target plant. The Agency recogni zes however, that it is likely that: (i) less than 100% of the paclobut razol would be taken up by a tree , (ii) less than 100% of what is taken up by the tree would be moved into the edib le parts of a tree; and, (iii) less than 100% of the product would be washed off the application site. Therefore, the Agency estimated RQs based on alternative scenarios, including 75%, 50% and 25% uptake, as well as 75%, 50% and 25% runoff. Estimated RQs for plants decrease, in proportion with the different uptake/runoff assumptions. For example, when 100% uptake is assumed, the estimated chronic RQ for birds is 2.3, but at 50% uptake the estimated chronic RQ is 1.17; and, when 100% runoff is assumed the RQ for terrestrial wetland plan ts is 70.37, but at 50% runoff the estimated RQ is 35.18. The Agency did not further characterize exposure and risk to mammals or birds with alternative assumptions about the amount of absorbed pacl obutrazol that would mo ve into the edible18 portions of the tree because of limitations in the ri sk assessment modeling tools. But it stands to

reason that less than 100% of th e applied amount of paclobutrazol would be available in edible portions of the tree. The open literature seems to suggest that most of the applied paclobutrazol

would be translocated to the trunk of trees (Arron, 1990; Sterre tt, 1985), this would lead to reduced exposure and lower RQs for mammals and birds.

To further characterize the potential frequency or magnit ude of a potential exposure from the basal tree drench use, the Agency considered the characteristics of the use of paclobutrazol— in other words, the types of trees that would be treated with paclobutrazol and how often they might be treated. According to the Massachusetts Department of Agricultural Resources, use of paclobutrazol on trees is typically ta rgeted at species of high aesthetic or monetary value, such as trees that may be in hi gh visibility locations ( e.g. , parks, historic downtowns, residential areas, or golf course settings). In addi tion, paclobutrazol is not typically applied to trees annually, but rather on a bi-annual basis or less. Therefore, while it is possible that a number of trees could be treated in one area on a single day, the Agency reasons that as a result of: (i) the type of tree that typically receives a pacl obutrazol application, and (ii) the number of applications typically made to a tree, exposure and risk to non-target organism s, particularly non-target terrestrial plants, is likely to be both spatially and temporally limited.

Therefore, when considering risk characteri zation, the Agency believes that potential risk to birds, mammals and non-target plants from soil injection use of paclobutr azol may exist but is likely lower than the estimates provided in the risk assessment, and may be both spatially and temporally limited. Therefore, the Agency is not pursuing ecological risk mitigation for this use as soil injection at this time. Risk mitigation for basal tree drench us e is detailed in section IV of

this document.

Risk from tree injection

Potential risks to mammals were identified from the tree injection use. However, the Agency believes that risks to mammals from this use are likely below estimated levels considering the low RQs and the assumptions used in risk assessment. The Agency assumed that all of the injected paclobutr azol would end up in edible plan t parts and be available for consumption by mammals. The Agency also as sumed that 100% of the mammals’ diet would

consist of foods contaminated w ith paclobutrazol residue s. In consideration of the low acreage that receives this use, i.e., it is typically used on select, hi gh-value trees in high-visibility neighborhoods (Massachusetts De partment of Agricultural Res ources, 2012), as well as the conservative assumptions utilized in the exposure assessment, the Agency does not think that the potential risks outweigh the benefi ts. The Agency is not pursuing ecological risk mitigation for this use pattern at this time.

Risk from turf uses

For paclobutrazol use on turf, potential risks were identified for mammals, fish, and aquatic invertebrates, but mainly for non-target terre strial plants.

Similar to the analysis for the basal tree drench use, risk calculations for non-target terrestrial animals and non-target terrestrial plants relied, in pa rt, on the assumption that 100% of19 the applied paclobutrazol would be available in the contaminated food source and that 100% would be available to non-target plants from runoff. As discussed above, this assumption is based upon a lack of chemical-specific data, a nd lower estimates of exposure and risk would result from alternative assumptions of uptake and runoff ( i.e. , 75%, 50% and 25%).

To characterize potential exposure, the Agency considered the typical use of paclobutrazol on turf. In a submission provide d by one of the techni cal registrants (email communication, December 12, 2014), confidential annual market data confirmed the Agency’s belief that most turf use of paclobutrazol is in golf course settings. While golf course management programs likely vary considerably from establishment to establishment, it is widely acknowledged that golf course se ttings are highly managed areas that often employ any number of best management practices (BMPs) to devel op and maintain a desired setting. Golf course establishments can employ BMPs for a number of reasons, such as to reduce the need for irrigation water, reduce the use of chemicals, as well as to control or reduce surface run-off (Virginia Golf Course Superintendents Asso ciation, 2012). Conseque ntly, many golf course maintenance BMPs can also directly or indi rectly reduce pesticide exposure to non-target terrestrial and aquatic plants. According to the Connecticut Department of Environmental Protection (2006), specific BMPs used in golf course management that would result in control, or

reduced surface runoff include:

 the use of retention ponds to capture runoff and stormwater;

 draining plans that include gr ass swales or diversions that direct runoff from the landscape to colle ction pond(s);

 the establishment of grassy swales, ve getated filter strips, and constructed wetlands integrated into the cour se landscape to filter runoff;

 construction of ponds in a “train” to treat site runoff, with the first pond catching the first flush with sediment and pollu tants, the second providing additional filtering, and the third as a withdrawal pond for irrigation of the course;

 lining of holding ponds that are expected to capture runoff with elevated chemical concentrations in order to prevent seepage of pollutant s into groundwater;

 proper irrigation and application of ch emicals to reduce leaching and runoff ( i.e.

, not applying chemicals before a possible storm event via use of weather forecasts)

 use of low volume sprinklers;

 employ soil cultivation techniques ( e.g. , spiking, slicing, and co re aerification) to improve water infiltration and minimize runoff;

 the use of riparian vegetated buffers along the banks of golf course wetlands, watercourses, and other water bodies to f unction as sediment filters that reduce pollutants in runoff;

 controlling pond overflow;

 locating pesticide and fertilizer mixing/lo ading areas away from watercourses and diverting runoff from thes e facilities into appropriate treatment areas;

 avoiding spraying pesticides when the soil is heavily saturate d to prevent runoff

Considering the characterization of estimated exposure and risk, and the prevalence of BMPs widely used in the golf course industry, the Agency beli eves that risk to non-target organisms, particularly, to aquatic organisms and pl ants, is likely to exist but is lower than that20 reflected in the risk assessment. However, the Agency notes that other turf uses of paclobutrazol, such as on turf in rights-of- way settings, do not represent the same level of landscape management and therefore could like ly represent scenarios of higher non-target

exposure.

Risk from spray drift

Potential risks from spray drift were also identified for the paclobut razol use on turf. The Agency believes that spray drift risks are li kely less than estimated. The majority of paclobutrazol use on turf is on golf course turf--sp ecifically tees, greens, fairways, and roughs. Spray drift may be less likely to leave a golf course due to the presence of tree barriers, hills, and other landscaping artifacts. Also, golf courses often use certain drift reduction technology to

reduce the volume and occurrence of spray drift, thes e include: enlarging spray droplet size, using higher viscosity formulati ons, adjusting spray pressure, a nd using low-volatility carriers (Balogh and Walker, 1992). In addition, certain BMPs and cultural practices are implemented by golf courses specifically to reduce the occurrence of drift, these include the use of spot treatments, “no spray” zones, use of covered boo ms, and avoidance of application during periods of high wind (Audubon International, 2015). In consideration of thes e factors, the Agency is not proposing risk mitigation specifically to address sp ray drift risks, although other risk mitigation listed herein may help indirectly ad dress spray drift risks.

Risk from ornamental uses

For use of paclobutrazol on ornamentals, pote ntial risks were iden tified for non-target mammals, non-target terrestrial a nd aquatic plants, and non-target aquatic species. The highest RQs were for terrestrial and aquatic plants resu lting from runoff. In characterizing potential

risks associated with the orname ntal uses of paclobutrazol, the Agency looked at exposure as it relates to assumptions, use, as well as BMPs that may be used in the ornamental production industry.

First, similar to its exposure analysis for the turf use and basal tree drench use of paclobutrazol, the lack of chemical-specific ru noff data required the Agency to assume that 100% of the paclobutrazol applied to ornament als would runoff and become available to nontarget plants and aquatic organisms. Use of alternative runoff assump tions would indicate RQs

lower than what was identified in the risk assessment.

With respect to the use of paclobutrazol on or namentals, the Agency’s analysis estimated risk based upon the use likely to result in the greatest environmental exposure ( i.e. , highest application rate or highest numbe r of applications). For potted ornamental use of paclobutrazol, this is a use rate of 200 ppm solution concentratio n for ornamental drench (equivalent to 6.08 lbs. ai/A). However, paclobutrazol labels are craf ted in a manner so as to identify a specific application rate for each separate ornamental speci es, or for small groups of ornamental species. The 200 ppm solution concentration is only indicated for a limited number of ornamental species (specifically amaryllis and freesia). These species reflect a very small portion of the floriculture market (less than 5%, according to USDA’s 2014 Fl oriculture Survey). While the Agency does not have typical application information for the many and varied orna mental species found on paclobutrazol labels, it notes that use rates for all other ornamental species listed on21 paclobutrazol labels are less than 100 ppm. Anecdotal information from one technical registrant (email communication, January 5, 2 015) indicated that in orna mental production, paclobutrazol is typically applied as a spray to bedding plan ts at a concentration of 30-50 ppm (equal to 0.03- 0.05 lbs ai/A) and typically applied as a drench to ornamental containers at a concentration of 1- 4 ppm (equal to 0.12 lb ai/A).

Finally, the Agency notes that similar to the golf course industry, the ornamental production industry also employs BMPs to reduce the need for irrigation, reduce the need for chemical application, and to cont rol and reduce the volume of runoff. According to Majsztrik et al. (2011), examples of BMPs fo r floriculture production include:

 use of calcined clays as substrate amendments that help absorb excess water/nutrients/chemicals;

 use of drip irrigation, micro-irrigation and precision applications to reduce the volume of runoff;

 use of containment ponds to hold surface water runoff;

 reuse of water from recaptured surface water for irrigation; and

 use of vegetated buffers for capturing se diment and nutrients/chemicals in runoff water; these are often used in association with containment ponds.

Information from the open literature provi des some indication of the ornamental production industry’s efforts to use BMPs that may, among other things, reduce or control surface water runoff. Two articles (Fain et al ., 2000, and Garber et al., 2002) found that, of container nurseries surveyed in Alabama, Georgia, and Florid a, 75%, 45% and 50%, respectively, have practices in place to capture runoff water. A survey of 85 nurseries in California in 2004 and again in 2006 (Salvatore et. al., 2010 ) found that th e percent of ornamental production faciliti es following BMPs was 57% and 65% respectively. While adoption of BMPs by the orname ntal production industry is ofte n voluntary, adoption in certain states is required to comply w ith state and local regulation of su rface water runoff. For example, California, Florida, Maryland, Oregon, and Te xas have adopted regulations mandating runoff capture or control by irri gated agricultural operations (Oki and White, 2011).

B. Risk Mitigation Measures

When considering: (i) assumptions used in ri sk estimates, (ii) risk characterization, (iii) the use of paclobutrazol, and (i v) other factors such as the existence of BMPs for certain industries, the Agency conclude s that potential risk may result from runoff associated with paclobutrazol use on trees (basal drench), on turf, and on ornamentals. The Agency believes that potential risks, particularly to non-target terrestrial and a quatic plants may be lowered by reducing runoff. Based upon this, the Agency enga ged the technical regist rants of paclobutrazol to develop revised label language fo r the three subject uses in orde r to reduce runoff, as well as to provide clarity and consistency across pacl obutrazol labels. All of the corresponding label changes referred to below can be found in sec tion IV.C and Appendix B of this document.

Label changes for use on trees

— basal tree drench22 The current paclobutrazol labels are unclear with respect to the application method for the basal tree drench use. Label language for th e basal tree drench use will be revised with the aim of: (i) reducing potential runoff, and (ii) speci fying the application equi pment for this use.

Label changes for use on turf

As discussed previously, the majority of pacl obutrazol use on turf occurs on golf courses. In addition to golf courses, paclobutrazol is also labeled for use on other managed turf sites such as park turf, athletic field turf , and institutional turf. However, paclobutrazol labels also specify use on turf in rights-of-way settings which are typically not highly managed. The Agency believes that use of paclobutrazo l on managed turf sites can be di stinguished from the rights-ofway use because at managed turf sites, runoff may be a variable that may be controlled via BMPs or cultural practices. In addition, unlike unmanaged turf site s, potential risks associated with paclobutrazol use at managed turf sites may be offs et by the benefits associated with these uses, namely the economic, aesthetic, or recreational value of golf courses, parks, or athletic fields. Therefore, in discussions with EPA, the tec hnical registrants of p aclobutrazol (Syngenta Crop Protection, Zhejiang Tide Cropscience, Fine Agrochemicals, and MacDermid Agricultural Solutions) have agreed to remove from product la bels, the use of paclobu trazol on turf in rightsof-way settings. Label language for the managed tu rf use will be revised to specify an irrigation requirement as well as a requirement to prohibit applications that woul d be subject to runoff

from a rain event.

Label changes for use on ornamentals

For ornamental spray/drench use, the Agency believes that there is potential risk to nontarget organisms from runoff in outdoor ornamental settings. Sim ilar to measures being required for the managed turf use, label language for th e ornamental use pattern is required that will specify an irrigation requirement as well as a re quirement to prohibit ap plications that would subject to runoff fr om a rain event.

Other Label Changes

In addition to label precautions for managing runoff, certain label changes will be made to improve the clarity of paclobutrazol labels with respect to the following:

Elimination of “greater-than” (>) signs fr om application rate information. Certain paclobutrazol labels are unclear with respect to drench/spray applications to ornamentals, because the application rate is expressed in term s of “greater-than” a certain value. Product labels must be as clear and specific as possible, and application rates expr essed as “greater-than” do not provide sufficient information for safe us e of a pesticide product. The Agency and the registrants of paclobutrazol products agreed to revise all affected labels to remove all “greaterthan” (>) signs and specify an upper bound appli cation rate. The following paclobutrazol EPA registrations are affected by this issue: 100-996, 228-679, 400-515, 62097-11, 62097-25, 79676- 79, 80697-3, and 82437-5.

Ensuring information, within a label, is c onsistent. The Agency notes that certain paclobutrazol labels have inconsis tencies in the ornamental use section between table text and23 the table headings, and need to be corrected. Fo r example, some labels have application rate language in one section of the la bel as “Application of this produc t will provide height control to most bedding plants at a concentration between 5 and 90 ppm”, yet text further below on the same label indicates application rates outside of this range. The Agency and registrants of paclobutrazol products agreed to re vise all affected labels to ensure consistency within the labeling. The following paclobutrazol EPA registra tions are affected by this issue: 79676-79, 400-515, 82437-5, 228-679, and 100-996.

Clarifying labels with respect to mist a nd fogging applications. Some paclobutrazol labels need to be clarified with respect to application by “mist” irri gation and “fogging.” The Agency confirmed with the technical registrants of paclobutrazol that f ogging is not an existing application method for paclobutrazol and therefor e, the Agency proposed that references to application via “fogging” or “fog system” be deleted from the labels. To prevent confusion, if “mist irrigation” is included on a label, the Ag ency and the registrants of paclobutrazol products agreed to delete any corresponding label langu age on the same label stating that “misting techniques will not produce desired results.” The following paclobutrazol EPA registrations are affected by this issue: 400-515, 62097-11, 62097-25, and 100-996.

C. Interim Registration Review Decision

EPA has completed quantitative human health and ecological risk assessments, including an initial endangered species analysis, for paclobutrazol.

The Agency determined that dietary (food + drinking water) risks to the general population or any population subgrou p are not of concern. The Agency also determined that residential and occupational ri sks are not of concern.

When initially scoping the registration review for paclobutrazol, EPA did not identify the need for any additional studies to evaluate poten tial effects on pollinators. However, since the

issuance of the June 2014 Guidance for Assessing Pesticide Risks to Bees 6 , EPA has begun to require these data where applicable. EPA is cu rrently determining whether additional pollinator data are needed for active ingredients in regist ration review whose dockets opened prior to June 2014. For those active ingredients where EPA determ ines that additional pollinator exposure and effects data are necessary to help make a final registration review decisi on, EPA intends to issue

a DCI to obtain these data. In the near fu ture, EPA will provide further information and guidance on this effort. The polli nator studies that c ould be required are included in Table 3 below. The Agency will require data it believes are needed to help inform the pollinator risk

assessment.

Table 3. Possible Pollinator Data Requirements for Paclobutrazol

Guideline # Study
850.3020* Acute contact toxicity study with ad ult honey bees (this study has been submitted to the Agency but has not yet been reviewed )

6 http://www2.epa.gov/sites/production/files/2014- 06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf24 850.3030* Honey bee toxicity of residues on foliage
850.3040** Field testing for pollinators

Non-Guideline* (OECD 213) Honey bee adult acute oral toxicity

Non-Guideline* (OECD 237) Honey bee larvae acute oral toxicity

Non-Guideline* Honey bee a dult chronic oral toxicity
Non-Guideline* Honey bee la rvae chronic oral toxicity
Non-Guideline** Residues in pollen a nd nectar/field re sidue analysis

Non-Guideline** (OECD 75) Semi-field testing for pollinators (tunnel or colony feeding studies)

*Tier 1 (Laboratory-based studies) **Tier 2 and 3 (Semi-field and full field colony-level studies) The need for a higher tier test for pollinators will be determi ned based upon lower-tiered tests and/or other lines of data and the need for a refined pollinator risk assessment.

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this Paclobutrazol Interim Registration Review Decision . Except for the EDSP, ESA and pollinator components of this case, the Agency has made the following Interim Registration Review

Decision for paclobutrazol:

 The Agency has not identified any additional data requirements to further inform either its human health effects or exposure database.

 No tolerance amendments are necessary for paclobutrazol.

 Based upon a lack of data, the Agency has not assessed potential ri sk from paclobutrazol

to terrestrial invertebrates. In the future , the Agency will determine whether pollinator data are required for paclobutrazol.

 The Agency is requiring the following data as data needs for registration review:

o Acute risk to estuarine/mari ne fish (guideline 850.1075)

o Chronic risk to estuarine/ma rine fish (guideline 850.1400)

o Chronic risk to estuarine/marine invertebrates (guideline 850.1350)

o Acute oral risk to passeri ne birds (guideline 850.2100)

o Translocation of paclobutrazol in plant parts

o Paclobutrazol uptake rate in tu rf, trees, and ornamentals

 The Agency has identified potential risk to several taxa from paclobutrazol, and has required certain changes to paclobutrazol registrations a nd their labeling to reduce potential risk from use on trees (as basal dr ench), use on turf, and use on ornamentals. These label changes are as follows:

Addition of the following label statem ent for use on trees as basal drench: “Prior to application, make a 2” deep furrow around the base of the tree near the point of contact between the soil and the tree trunk. Apply the required dose [x ml for the25 application rate and tree size DBH]. Care fully pour the diluted mixture of [product name] into the furrow with a graduated cont ainer/jug or with a handheld hose connected to a truck-mounted tank/hydraulic sprayer . To avoid possible product runoff after applying, refill the furrow with untreated soil.”

Addition of the following label statement for use on turf: “After [product name] application, water-in within 24 hours to limit surface movement, but not to the point of runoff. To prevent product runoff, time applic ations to allow for watering-in and maximum absorption into tr eated turf prior to a rain event.”

“Do not apply [product name] to turf within rights-of-ways.”

Addition of the following label st atements for use on ornamentals: “In outdoor commercial ornamental and nursery uses, follow foliar applications of [product name] by irrigation within 24 hours to remove product fr om foliage and limit surface movement. If overhead irrigation is not available, time applications to allow [product name] to dry on the treate d surface prior to a rain event.”

“To limit unwanted surface runof f in outdoor ornamental uses, do not apply when growth

media is saturated.”

Certain other changes to paclobutrazol labe ls are required to improve clarity and consistency:

o Elimination of “greater-than” (>) signs from application ra te information and addition of upper rate maximums.

o Revision of paclobutrazol labels to ensure te xt, within a label, regarding application

directions is consistent.

o Clarification of paclobutrazol labels with respect to application as a mist or fog.

In this Interim Registration Review Decision , EPA is making no human health or environmental safety findings associated with the EDSP screening of paclobutrazol, risk to pollinators, nor is it making a complete enda ngered species finding. The Agency’s final registration review decision for paclobutrazol will be issued on ce an ESA Section 7 consultation with the Services has taken place, an EDSP FFDCA section 408(p) determination has been made, and the pollinator risk assessment has been completed.



### V. NEXT STEPS AND TIMELINE

A. Implementation of Mitigation Meas ures and Issuance of Required Data

Amended labels that include the risk mitigati on measures required in this interim decision must be submitted to the Agency for approval within 60 days following issuance of this Interim Registration Review Decision . A summary of the required mitigation measures are described in Appendix A, and changes to labels are described in Appendix B. In the near future the Agency will issue a DCI for the data requirements listed in section IV. C.

B. Final Registration Review Decision26 EPA will make a final registration review d ecision for paclobutrazol after ESA Section 7 consultation with the Services has taken pl ace, the pollinator risk assessment has been completed, and an EDSP FFDCA section 408(p) determination has been made.

References

Arron, G. (1990). Translocation of Uniconazole Af ter Trunk Injection of Silver Maple Saplings. Journal of Plant Growth Regulation , 9, 141-146.

Audubon International. (2015). Environmental Ma nagement Practices for Golf Courses. Retrieved June 17, 2015, from http://www.auduboninterna tional.org/factsheets

Connecticut Department of Environmental Prot ection. (2006). Best Mana gement Practices for Golf Course Water Use. Retrieved February 5, 2015, from www.ct.gov/deep/lib/deep/water_inland/ diversions/golfcoursewaterusebmp.pdf

Balogh, J. C. & Walker, W. J. (1992). Golf Course Management & Construction: Environmental

Issues . Chelsea, MI: United States Golf Association.

Fain, G. B., Gilliam, C. H., Tilt, K. M., Olive, J. W., and Wallace, B. (2000). Survey of Best Management Practices in Cont ainer Production Nurseries. Journal of Environmental

Horticulture , 18(3), 142-144.

Garber, M. P., Ruter, J. M., Midcap, J. T., and Bondari, K. (2002). Survey of Container Nursery Irrigation Practices in Georgia. HortTechnology , vol. 12, no. 4, 727-731.

Majsztrik, J. C., Ristvey, A. G ., and Lea-Cox, J. D. (2011). Wate r and Nutrient Management in

the Production of Container-Grown Ornamentals. Horticultural Reviews , 38, 253-297.

Massachusetts Department of Agricultural Re sources. (2012). Paclobut razol: Review Conducted by MDAR and MassDEP for Use in Sensitive Areas of Rights-of-Way in Massachusetts. Retrieved February 4, 2015, from www.mass.gov/eea/docs/agr/pesticid es/rightofway/docs/paclobutr azol-review-jan -2012.pdf

Oki, L. R. & White, S. A. (2011). Ecological A pproaches Used in Nurseries to Treat Water. University of California UCNFA News , 15, 1-6.

Personal Communications from Technical Regist rants of Paclobutrazol Used in EPA’s Risk Management Decision. December 2014-June 2015. Available in docket EPA-HQ-OPP-2006-

0109 at www.regulations.gov

.

Salvatore, S. M., Newman, J., Mochizuki, M., Zu rawski, D., Merhaut, D. J., and Faber, B. (2010). Nurseries Surveyed in Southern Califor nia Adopt Best Practices for Water Quality. California Agriculture , vol. 64, no. 1, 26-30.27 National Agricultural Sta tistics Service, United States De partment of Agriculture. (2014). Floriculture Crops 2013 Summary. Retrieved June 11, 2015, from http://www.nass.usda.gov/Statisti cs_by_State/New_Jersey/Publica tions/Floriculture_Statistics/Fl orCrop-06-19-2014.pdf

Sterrett, J. P. (1985). Paclobutr azol: A Promising Growth Inhi bitor for Injection into Woody

Plants. Journal of the American Society for Horticultural Science , 110(1), 4-8.

Virginia Golf Course Superintendents Associ ation. (2012). Environmental Best Management Practices for Virginia’s Golf C ourses. Retrieved June 11, 2015, from http://www.vgcsa.org/sites/im ages/373/VirginiaBMP.pdf28 Appendix A: Summary of Required Risk Mitigation for Paclobutrazol

Affected Population(s) Source of
Exposure Route of Exposure Duration of
Exposure Risk(s) of Concern Mitigation

Humans (occupational handlers) Direct contact Dermal absorption Short

‐ term Short

‐ term Label advisory specifying application
equipment to be

used for basal tree

drench

Terrestrial plants, aquatic plants Runoff Systemic

direct contact,

water Short

‐ term
Long

‐ term Short

‐ term
Long

‐ term Removal of turf use
within rights

‐ of

‐

ways; requirement

for creation of 2

inch furrow for

basal tree drench applications; label

advisories for
managing runoff

Mammals Dietary

Water Ingestion Long

‐ term Long

‐ term Deletion of turf use
within rights

‐ of

‐

ways; label

advisories for
managing runoff

Birds, reptiles,

and terrestrial

‐ phase amphibians Dietary

Water Ingestion Long

‐ term Long

‐ term Deletion of turf use
within rights

‐ of

‐

ways; label

advisories for
managing runoff

Aquatic fish,
invertebrates,

and amphibians Runoff Water Short

‐ term
Long

‐ term Short

‐ term
Long

‐ term Deletion of turf use
within rights

‐ of

‐

ways; label

advisories for
managing runoff29Appendix B: Paclobutrazol Label TableSummary of Required Labeling Changes for Paclobutrazol UsesDescriptionAmended Labeling Language for Paclobutrazol End Use ProductsPlacement on LabelEnd Use ProductsLanguage for basal treedrench application“Prior to application, make a 2” deep furrow around the base of the tree near the point of contact between the soiland the tree trunk. Apply the required dose [x ml for theapplication rate and tree size DBH]. Carefully pour thediluted mixture of [product name] into the furrow with a graduated container/jug or with a handheld hose connectedto a truck-mounted tank/hydraulic sprayer. To avoid possible product runoff after applying, refill the furrow withuntreated soil.”Use DirectionsLanguage for turfapplications“After [product name] application, water-in within 24 hours tolimit surface movement, but not to the point of runoff.To prevent product runoff, time applications to allow for watering-in and maximum absorption into treated turf priorto a rain event.”“Do not apply [product name] to turf within rights-of-ways.”Use DirectionsLanguage for applicationto outdoor ornamentals“In outdoor commercial ornamental and nursery uses, followfoliar applications of [product name] by irrigationwithin 24 hours to remove product from foliage and limit surface movement. If overhead irrigation is not available,time applications to allow [product name] to dry on the treated surface prior to a rain event.”“To limit unwanted surface runoff in outdoor ornamental uses, do not apply when growth media is saturated.”Use DirectionsRemoval of references to“fogging” and “fogsystem”Delete references to “fogging” and “fog system” from label.ApplicationTechniquesClarify use of mistirrigationDelete “misting techniques will not produce desired results” from label.ApplicationTechniquesClarification ofornamental use ratesMaintain consistency between table headings and table text for applications to ornamentals.Use Directions30Clarification ofornamental use ratesDelete “>” signs from the label. Rates must be stated aseither a numerical digit ora numerical range with a clearupper bound rate.Use Directions